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Mineral exploration of the Nechako plateau, Central British Columbia, using lake sediment geochemistry Hoffman, Stanley Joel 1976

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1 MINEBAL EXPLORATION OF THE NECHAKO PLATEAU, CENTRAL BRITISH COLOMBIA, USING LAKE SEDIMENT GEOCHEMISTRY by STANLEY JOEL HOFFMAN B . S c , M c G i l l U n i v e r s i t y , 1969 M.Sc, U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1972 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIBEMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES (Department of G e o l o g i c a l S c i e n c e s ) We a c c e p t t h i s t h e s i s as co n f o r m i n g t o the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA September, 1976 (cT) S t a n l e y J o e l H o f f m a n , 1976 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d that c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f G e o l o g y The U n i v e r s i t y o f B r i t i s h Co lumbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date O c t o b e r 1, 1976 i i MINEBAL EXPLORATION OF THE NECHAKO PLATEAU, CENTRAL BRITISH COLOMBIA, USING LAKE SEDIMENT GEOCHEMISTRY A B S T R A C T A lake sediment geochemical survey was undertaken over the Nechako plateau, c e n t r a l B r i t i s h Columbia, to test a p p l i c a b i l i t y of lake sediment sampling to regional exploration. Organic-rich samples were c o l l e c t e d near the centres of approximately 500 lakes on a h e l i c o p t e r - a s s i s t e d survey covering some 16,000 km2. I t was found that lakes overlying each of f i v e major l i t h o l o g i e s contain d i s t i n c t i v e suites of trace metals, and that r e g i o n a l variations of Cu, Mo, Pb, Zn, Ni, Cr, Sr, Ba, Ag, Co, V, and Ga are r e l a t e d to differences i n underlying geology, whereas anomalous l e v e l s of Cu, Mo, Pb, and Zn r e f l e c t miaeralized bedrock or rock types favourable to the occurrence of sulphide concentrations. Possible mechanisms of anomaly generation were examined by detailed studies of the Capoose Lake Cu-Mo-Pb-Zn anomaly, and the Fish and Portnoy Lake Cu-Mo anomalies, both previously defined by the regional survey. Capoose Lake, a l a r g e c l i g o t r o p h i c lake, occupies a *U,-shaped v a l l e y , and i s characterized by Fe~ and Mn-rich and organic-poor sediment. In contrast. Fish and Portnoy Lakes are small dystrophic and eutrophic ponds, re s p e c t i v e l y , completely surrounded by bogs. They contain organic-rich and Fe- and Mn-poor sediment. These studies show that anomalous accumulation of Cu, Zn, and Mo i n s o i l s , streams, and lakes r e f l e c t s weathering of sulphide occurrences. Cu, Zn, Mo, Fe, and Mn concentrations associated with i i i c h e m i c a l phases c o m p r i s i n g overburden m a t e r i a l s were p a r t i t i o n e d u s i n g p a r t i a l e x t r a c t i o n e x p e r i m e n t s . Cu, Zn, and Mo a n o m a l i e s i n s o i l s r e f l e c t i n g m i n e r a l o c c u r r e n c e s a r e commonly h y d r c m o r p h i c , a l t h o u g h a n o m a l i e s formed by m e c h a n i c a l p r o c e s s e s a r e prominent near bedrock e x p o s u r e s . Cu and Zn a r e more f i r m l y bound i n s o i l s and stream s e d i m e n t s t h a n l a k e s e d i m e n t s , w i t h the p r o p o r t i o n o f t h e s e elements a s s o c i a t e d w i t h (and presumably scavenged by) amorphous Fe o x i d e s i n c r e a s i n g from s o i l s t o stream s e d i m e n t s t o l a k e s e d i m e n t s . Mo i s h e l d by both amorphous and c r y s t a l l i n e Fe o x i d e s . An i n c r e a s e i n t h e s c a v e n g i n g a b i l i t y o f amorphous Fe o x i d e s from s o i l s t o st r e a m s s e d i m e n t s a l s o i s o b s e r v e d i n t h e F i s h and Portnoy L a k e s a r e a . However t h e b u l k o f t h e Cu, Zn, and Mo i n t h e l a t t e r two l a k e s i s a p p a r e n t l y bound t o o r g a n i c m a t t e r . M e t a l l e v e l s w i t h i n l a k e s e d i m e n t s a r e h i g h l y v a r i a b l e , and w i t h i n each l a k e t h e maximum range o f c o n c e n t r a t i o n s commonly exceeds an o r d e r o f magnitude. Zones of g r e a t e s t Cu, Zn, and Bo en r i c h m e n t a r e w i t h i n 10 t o 150 m from s h o r e , downslope from m i n e r a l o c c u r r e n c e s . M e t a l a c c u m u l a t i o n f a v o u r s zones s l i g h t l y above t h e base o f t h e n e a r s h o r e s l o p e , where t h e volume o f emerging groundwater presumably i s g r e a t e s t . A n o m a l i e s a r e a l s o g e n e r a t e d by i n p u t s o f m e t a l - r i c h f i n e s c a r r i e d by s t r e a m s . C o n s e q u e n t l y f o r maximum anomaly c o n t r a s t , samples s h o u l d be c o l l e c t e d from zones where d i s s o l v e d m e t a l s o r m e t a l - r i c h s i l t and c l a y a r e f l o w i n g i n t o a l a k e . Coarse c l a s t i c s e d i m e n t s h o u l d be a v o i d e d . MINEBAL EXPLORATION OF THE NECHAKO PLATEAU, CENTRAL BRITISH COLUMBIA, USING LAKE SEDIMENT GEOCHEMISTRY TABLE OF CONTENTS ABSTRACT i i TABLE OF CONTENTS i v LIST OF TABLES X LIST OF FIGURES XV ACKNOWLEDGEMENTS Xxv CHAPTER 1 1 INTRODUCTION TO LAKE SEDIMENT GEOCHEMISTRY ................ 1 I STATEMENT OF THE PBOBLEM .............................. 1 II FACTORS AFFECTING METAL CONTENT OF LAKE SEDIMENTS ..... 2 I I I HISTORY OF LAKE SEDIMENT GEOCHEMISTRY APPLIED TO MINERAL EXPLORATION 11 IV SUMMARY 14 CHAPTER 2 16 DESCRIPTION OF THE STUDY AREA ..............................16 I LOCATION AND ACCESS 16 II REGIONAL GEOLOGY (Fig 3) 16 III CLIMATE 20 17 TOPOGRAPHY AND DRAINAGE ...............................20 V SOILS AND VEGETATION 22 CHAPTER 3 25 MINEBAL EXPLOBATION OF THE NECHAKO PLATEAU USING LAKE SEDIMENT GEOCHEMISTRY .................................. 25 I RECONNAISSANCE SURVEY 25 A. Introduction 25 B. Sample c o l l e c t i o n , preparation and analysis ........ 26 C. Geochemical r e s u l t s 27 1. Relationship between trace element d i s t r i b u t i o n s and geology .................................. 27 2. Influence of organic matter and Fe on trace metal l e v e l s ................................. 38 3. Relevence to mineral exploration ............... 42 I. Discussion ......................................... 45 E. .Application to exploration ......................... 48 F. Summary ............................................ 52 CHAPTER 4 53 ANALYTICAL TECHNIQUES ... .53 I SAMPLE COLLECTION AND PREPARATION 53 A. Introduction ....................................... 53 B. Stream, spring and lake sediments .................. 54 C. Stream, spring and lake water ...................... 55 D. S o i l s 57 II SAMPLE EXTRACTION PROCEDURES .......................... 58 A. S o i l , spring and sediment samples ..............,.,.58 1. N i t r i c and perchloric acid digestion ........... 58 2. P a r t i a l extractions ............................ 59 3. Sequential p a r t i a l extractions ................. 60 4. Sand content .................................., 63 5. S o i l pH determination .......................... 63 6. Organic matter content ......................... 64 7. Size f r a c t i o n analysis ......................... 65 8. Clay mineral i d e n t i f i c a t i o n .................... 65 B. Stream, spring and lake water samples .............. 66 vi III ANALYTICAL TECHNIQUES 66 A. Emission spectroscopy .............................. 66 B. Atomic absorption spectrophotometry ................ 67 C. Colorimetry ....... ................................. 73 CHAPTER 5 74 PARTIAL AND SEQDENTIAL EXTRACTION EXPERIMENTS ............. 74 I PARTIAL EXTRACTION TECHNIQUES ......................... 74 A. Introduction 74 B. Selection of reagents .............................. 75 C. Geochemical r e s u l t s ................................ 78 E. Discussion 80 II SEQUENTIAL EXTfiACTICN TECHNIQUES ...................... 83 A. Introduction ................................ ...,... 83 E. Choice of reagents and order of sample treatment Fig 12) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 1. Sodium hypochlorite, pH 9.5 .................... 84 2. A c i d i f i e d d i s t i l l e d water, pH 3.0 (dilute hydrochloric acid) ........................... 85 3. Hydroxylamine hydrochloride, pH 2*5 ............ 86 4. Acid ammonium oxalate, pH 3.5 .................. 86 5. Citrate^bicarbonate-dithionite ( d i t h i o n i t e ) , pH 7.0 ....................................... 87 6. Hydrogen peroxide, pH 3.5 87 7. N i t r i c and perchloric acids ..^................. 88 C. Geochemical r e s u l t s ................ ...........••••• 88 1. Introduction ...................................,88 2. S o i l s 89 3. Stream sediments ...............................98 v i i 4. Lake sediments ................................. 98 0. Discussion .........................................102 CHAPTER 6 114 ORIENTATION STUDIES AT CAPOOSE, AND FISH AND PORTNOY LAKES 114 I DETAILED LAKE SEDIMENT SURVEYS ...114 A. Introduction ..114 E. Capoose Lake 115 1. Introduction .......................115 2. Description of the study area ..................119 a. Geology and mineralization .................. 119 b. Topographic setting and drainage ............ 122 c. S o i l s and vegetation ........................ 125 d. Lake description • 126 e. Sample c o l l e c t i o n ........................... 131 3. Geochemical results ............................ 149 a. Geochemical dispersion from the North Anomaly 149 b. Other inputs to Capoose Lake ............... 171 c. Geochemical dispersion from the Green Lake area 176 i . Introduction .....176 i i . Pb - Zn - Cu - Ag anomaly ............. 176 i i i . Cu - Zn - Ag anomaly ................. 190 i v . Cu - Ag anomaly ....................... 191 d. Trace metal d i s t r i b u t i o n i n lake sediment ..192 4. Discussion ..................................... 237 5. Summary ........................................ 252 C. Fish and Portnoy Lakes 255 v i i i 1. Introduction 255 2. Description of the study area .................. 257 a. Geology and mineralization (Fig 58) ........ 257 b. Topographic setting and drainage ........... 259 c. S o i l s and vegetation ....................... 260 d. Lake descriptions .....261 e. Sample c o l l e c t i o n ....263 J . Geochemical results 266 a. ,Fish Lake ..... ............................. 266 i . Geochemical dispersion towards Fish Lake ................................. 266 i i . Trace metal d i s t r i b u t i o n i n lake sediment ............................ 281 b. Portnoy Lake ....292 i . Geochemical dispersion towards Portnoy Lake .................................292 i i . Trace metal d i s t r i b u t i o n i n lake sediment ............................293 4. Discussion . i 298 5. Summary .. . . ... ...... ................301 CHAPTER 7 ....303 FINAL DISCUSSION AND CONCLUSIONS .......................... 303 I GENERAL DISCUSSION ,...303 A. A model - genesis of lake sediment anomalies .......303 B. Comparison with other lake sediment surveys 311 C. Application to exploration ......................... 324 1. Choice of sample density .....324 2. Degree of success of lake sediment surveys .....329 3. Suggestions for future surveys ................. 331 D. Summary .333 1. Conclusions 337 BEFEBENCES 339 X LIST OF TABLES TABLE NUMBER I Summary of watershed, lake and sediment parameters l i k e l y to strongly influence trace metal l e v e l s of lake sediments ..............................11 II Trace element content of lake sediments (ppm) associated with the p r i n c i p l e geological units, Rio Tinto survey of the Nechako plateau ........ ,34 III Comparison of trace metal l e v e l s (ppm) associated with Jurassic/Cretaceous intrusions, Takla volcanics, t h e i r mutual contact, and Capoose Lake 36 IV Correlation of trace metal l e v e l s with loss on i g n i t i o n and lake depth, regional survey ....... 39 V Trace metal l e v e l s (ppm) i n lake sediment samples, divided on the basis of LOI classes, from the Nechako plateau ................................ 41 VI Geology and geochemistry of mineral prospects on the Nechako plateau ............................ 43 VII Comparison of trace metal content (ppm) i n d e l t a i c and central basin sediment of Capoose Lake, based on samples c o l l e c t e d on the reconnaissance survey ......................................... 45 VIII Types and numbers of geochemical samples c o l l e c t e d during 1970-1971 . . . i 54 II Summary of detailed lake sediment sampling of three lakes on the Nechako plateau ............. 54 x i X Comparison of trace metal data (ppb) i n f i l t e r e d and u n f i l t e r e d water samples ................... 57 XI Spectrographic eguipment and standard operating conditions ................................. .... 68 XII Operation c h a r a c t e r i s t i c s and precision at the 95% confidence l e v e l of emission spectrometric analysis (Doyle, 1971) ......................... 69 XIII Operational c h a r a c t e r i s t i c s of atomic absorption analysis 70 XIV Summary of elements determined for di f f e r e n t study areas and extraction procedures ................71 XV Precision of atomic absorption analysis at the 9 5 % confidence l e v e l estimated by analysis of paired samples ........................................ 73 XVI Percent extraction of Cu, Zn, Fe, Mn and Ho from the organic f r a c t i o n of s o i l s , stream sediments and lake sediments, Capoose Lake, and Fish and Portnoy Lake areas 94 XVII Percent extraction of Cu, Zn, Fe, Mn and Mo from the amorphous Fe oxide f r a c t i o n of s o i l s , stream sediments and lake sediments, Capoose Lake, and Fish and Portnoy Lake areas .................... 95 XVIII Percent-extraction of Cu, Zn, Fe, Mn and Mo from the s i l i c a t e residue f r a c t i o n of s o i l s , stream sediments and lake sediments, Capoose Lake, and Fish and Portnoy Lake areas .96 XIX Trace metal content (ppm) of Capoose Lake nearshore, delta, and central basin sediment ...128 x i i XX F i e l d determination of bicarbonate, sulphate and pH i n stream and lake water samples ............ 131 XXI Trace element content (ppm) of d i f f e r e n t s o i l horizons, Capoose Lake area, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid attack .................. 134 XXII Sequential extraction of copper, zinc, i r o n , manganese and molybdenum (percent extraction) from selected s o i l p r o f i l e s , Capoose and Green Lake areas ..................................... 152 XXIII Comparison of trace element content (ppm) of Capoose, Fish and Portnoy Lake area stream sediment, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid digestion ................................. 169 XXIV Sequential extraction of copper, zinc, i r o n , manganese and molybdenum (percent extraction) from selected stream and seepage sediments. Capoose, Green, and Fish and Portnoy Lake area .170 XXV Trace element content (ppm) of stream sediment around the margin of Capoose Lake, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid digestion .....172 XXVI Trace element content (ppm) of the -80 mesh, and s i l t and clay fra c t i o n s of selected stream sediments at the margins of Capoose Lake, and selected-lake sediments from within Capoose Lake. 173 XXVII Comparison of trace element content (ppb) of Capoose, Fish and Portnoy Lake area stream water. .........................................174 x i i i XXVIII Trace element content (ppb) of seepage water around the margin of Capoose Lake 175 XXIX Trace element content (ppm) of d i f f e r e n t s o i l horizons. Green Lake area, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid attack 188 XXX Comparison of trace element content (ppb) of Capoose, Fish and Portnoy Lake area lake water .195 XXXI Multiple regression analysis of the trace metal content of s u r f i c i a l sediment of Capoose Lake, assuming t o t a l i r o n , organic matter and lake depth independent variables ....................210 XXXII Location of Capoose Lake core samples ............234 XXXIII Trace element content (ppa) i n lake sediment cores from*Capoose Lake, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid attack ..................235 XXXIV Comparison of trace element content (ppm) of Capoose, Fish and Portnoy Lake area lake sediment, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid digestion ....................247 XXXV Trace element content (ppm) of d i f f e r e n t s o i l horizons. Fish and Portnoy Lake area, -80 mesh f r a c t i o n , n i t r i c / p e r c h l c r i c acid attack ........271 XXXVI Correlation c o e f f i c i e n t s (r>±0.40) for variables in Fish and Portnoy Lakes 288 XXXVII Multiple regression analysis of the trace metal content of s u r f i c i a l sediment of Fish Lake, assuming t o t a l i r o n , organic matter and lake depth independent variables .................... 289 xiv XXXVIII Trace element content (ppm) i n lake sediment cores from Fish and Portnoy lakes, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid attack .291 XXXIX Sequential extraction of copper, zinc, ir o n , manganese and molybdenum (percent extraction) from selected s o i l p r o f i l e s . Fish and Portnoy Lake area ...................................... 292 XV LIST OF FIGDBES PIGUBE BOMBER 1 Model r e l a t i n g inputs and deposition of trace metals i n lake basins (modified after Timperley and Allan, 1974) 3 2 Location of and access on the Nechako plateau, central B r i t i s h Columbia ........................ 17 3 Regional geology of the Nechako plateau (Tipper, 1961, 1963)-ii.....,............................. 18 4 Sample lo c a t i o n map, Nechako plateau lake sediment survey .v........................................ 26 5 Nechako plateau lake sediment survey f o r n i c k e l ... 28 6 Nechako plateau lake sediment survey f o r molybdenum. ........... ...... .................... 29 7 Nechako plateau lake sediment survey f o r copper ... 30 8 Nechako plateau lake sediment survey f o r lead ..... 31 9 Nechako plateau lake sediment survey f o r zinc ..... 32 10 Correlation of Cu levels and LOI measurements i n lake sediments of the Nechako plateau ........... 40 11 «Recce-data w format f o r recording reconnaissance lake sediment information, f o r f i e l d applications. ................................... 50 12 Sequential cold extraction procedure ..............61 13 Trace element solution by d i l u t e hydrochloric a c i d , EDTA, neutral ammonium acetate, and acid ammonium oxalate on selected lake sediment samples, Nechako plateau, B. C. .......................... 90 x v i 14 Sequential extraction of Cu, Zn # Fe, fin, and Mo from selected stream sediment and s o i l samples. North Anomaly and Capoose Lake area, Nechako plateau, B. C. .................................. 91 15 Sequential extraction of Cu, Zn, Fe, Mn, and Mo from selected stream sediment and s o i l samples. Green Lake area, Nechako plateau, B. C. ......... 92 16 Sequential extraction of Cu, Zn, Fe, Mn, and Ho from selected stream sediment and s o i l samples, Fish and Portnoy Lake area, Nechako plateau, B. C . 93 17 Sequential extraction of Cu, Zn, Fe, Mn and Mo from selected lake sediment samples, Capoose, Fish and Portnoy Lakes, Nechako plateau, B. C. ........... 99 18 Comparison of sequential and simple p a r t i a l extraction of Cu, Zn # Fe, Mn, and Mo (percent extraction) from selected lake sediment samples, Nechako plateau, B. C. .......................... 105 19 Comparison of sequential and simple p a r t i a l extraction of Cu, Zn, Fe, Mn, and Mo (ppm) from selected lake sediment samples, Nechako plateau, B. C. 106 20 Comparison of the sequential e x t r a c t a b i l i t y of Cu, Zn, Fe, Mn, and Mo from s o i l , stream sediment and lake sediment samples, Capoose Lake area ........109 21 Comparison of the sequential e x t r a c t a b i l i t y of Cu, Zn, Fe, Mn, and Mo from s o i l , stream sediment and lake sediment samples. Fish and Portnoy Lake x v i i area............................................110 22 Mineral occurrences, and o f f i c i a l and u n o f f i c i a l locale names of the Capoose and Green Lake areas 116 23 Sample locations at Capoose Lake and the North Anomaly described i n text ....................... 117 24 Sample locations near Green Lake described i n text 118 25 Location, geology and mineralization, Capoose Lake granodiorite, c e n tral B r i t i s h Columbia (from Boyle and Troup, 1975) ................. ......... 120 26A Distribution of copper values greater than 50 ppm in s o i l s (courtesy A. Troup, Bio Tinto) ......... 132 26E Dist r i b u t i o n of molybdenum values greater than 5 ppm i n s o i l s (courtesy A. Troup, Bio Tinto) .....132 26C Dist r i b u t i o n of lead values greater than 15 ppm i n s o i l s (courtesy A. Troup, Bio Tinto) ............ 133 26D Distribution of zinc values greater than 150 ppm i n s o i l s (courtesy A. Troup, Bio Tinto) ............ 133 27A Variation of copper (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Line 1 ............ 135 27B Variation of zinc (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Line 1 ............ 136 27C Variation of molybdenum (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Line 1 ............ 137 28A Variation"of copper (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Line 2 ............ 138 28E Variation of zinc (ppm) in s o i l s across the landscape, -80 mesh f r a c t i o n . Line 2 ............ 139 28C Variation of molybdenum (ppm) i n s o i l s across the x v i i i landscape, -80 mesh f r a c t i o n . Line 2 ............ 140 29A Variation of copper (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Line 3 ............ 142 29B Variation of zinc (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Line 3 ............ 143 29C Variation of molybdenum (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Line 3 ............ 144 29D Variation of lead (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Line 3 ............ 145 30A Variation of copper (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Lines 4 and 5 .....146 30B Variation of zinc (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n , Lines 4 and 5 .....147 30C Variation of molybdenum (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Lines 4 and 5 •••..148 30D Variation of lead (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Lines 4 and 5 .....149 31 a North Anomaly*- Capoose Lake, copper (ppb) i n water. ..................... ............ ......... 156 31B North Anomaly - Capoose Lake, copper (ppm) i n sediments, -80 mesh f r a c t i o n .................... 157 31C North Anomaly - Capoose Lake, copper (ppm) i n s o i l s , -80 mesh f r a c t i o n 158 32A North Anomaly - Capoose Lake, zinc (ppb) i n water .159 32B North Anomaly - Capoose Lake, zinc (ppm) i n sediments, -80 mesh f r a c t i o n ............. ..160 33A North Anomaly - Capoose Lake, molybdenum (ppb) i n water ........................,..................161 xix 33B North Anomaly - Capoose Lake, molybdenum (ppm) i n sediments, -80 mesh f r a c t i o n .....162 33C North Anomaly - Capoose Lake, molybdenum (ppm) i n s o i l s , -80 mesh f r a c t i o n ........................ 163 34A North Anomaly - Capoose Lake, iron (ppb) i n water .164 34B North Anomaly - Capoose Lake, iron (5J) i n sediments, -80 mesh f r a c t i o n .................... 165 35A North Anomaly - Capoose Lake, manganese (ppb) i n water ...........................................166 35B North Anomaly - Capoose Lake, manganese (ppm) i n sediments, -80 mesh f r a c t i o n .................... 167 36 North Anomaly - Capoose Lake, organic matter (%) i n lake sediment ., .................................168 37A Green Lake Anomaly - lead (ppm) i n stream sediments, -80 mesh f r a c t i o n 177 37E Green Lake Anomaly - lead (ppm) i n top of the " f l " s o i l horizon, -80 mesh fra c t i o n ................. 178 38A Green Lake Anomaly - zinc (ppb) i n stream water ...179 38B Green Lake Anomaly - zinc (ppm) i n stream sediments, -80 mesh f r a c t i o n .................... 180 38C Green Lake Anomaly - zinc (ppm) i n top of the " f l " s o i l horizon, -80 mesh f r a c t i o n ,.,.,....181 391 Green Lake Anomaly - copper (ppb) i n stream water .182 39B Green Lake Anomaly - copper (ppm) i n stream sediments, -80 mesh f r a c t i o n .................... 183 39C Green Lake Anomaly - copper (ppm) i n top of the MB*» s o i l horizon, -80 mesh f r a c t i o n ....184 40A Green Lake Anomaly - s i l v e r (ppm) i n stream XX sediments, -80 mesh f r a c t i o n 185 40E Green Lake Anomaly - s i l v e r (ppm) i n top of the "B" s o i l horizon, -80 mesh f r a c t i o n ................. 186 41 Green Lake Anomaly - pH of stream water ........... 187 42 Trace element content i n lake sediment (ppm) and lake water (ppb) along Lines B and A, Capoose Lake ..:........ 197 43 Trace element content i n lake sediment (ppm) and lake water (ppb) along Line C, Capoose Lake .....198 44 Trace element content i n lake sediment (ppm) and lake water (ppb) along Line D, Capoose Lake .....199 45 Trace element content i n lake sediment (ppm) and lake water (ppb) along Line E, Capoose Lake .....200 46 Trace element content i n lake sediment (ppm) and lake water (ppb) along Line F, Capoose Lake .,.,.201 47 Trace element content i n lake sediment (ppm) and lake water (ppb) along Line G, Capoose Lake .,,.,202 48 Trace element content i n lake sediment (ppm) and lake water (ppb) along Lines H and I, Capoose Lake ............. 203 49 Trace element content i n lake sediment (ppm) and lake water (ppb) along Line J , Capoose Lake .....204 50 Trace element content i n lake sediment (ppm) and lake water (ppb) along Line K, Capoose Lake .....205 51 Trace element content i n lake sediment (ppm) and lake water (ppb) along Line L, Capoose Lake .....206 52 Dis t r i b u t i o n of lead (ppm) i n Capoose Lake sediment. ...................... .... ............. 207 xxi 53A Sequential extraction of copper from lake sediments along Line K, Capoose Lake ........212 53B Sequential extraction of zinc from lake sediments along Line K, Capoose Lake ...................... 213 53C Sequential extraction of iron from lake sediments along Line K, Capoose Lake .214 53D Sequential extraction of manganese from lake sediments along Line K, Capoose Lake ............ 215 53E Sequential extraction of molybdenum from lake sediments along Line K# Capoose Lake ............ 216 54A Sequential extraction of copper from lake sediments along Line C, Capoose Lake ...................... 217 54B Sequential extraction of zinc from lake sediments along Line C, Capoose Lake ...................... 218 54C Sequential extraction of ir o n from lake sediments along Line C, Capoose Lake ......219 54D Seguential extraction of manganese from lake sediments along Line C, Capoose Lake ............ 220 54E Sequential extraction of molybdenum from lake sediments along Line C, Capoose Lake ............ 221 55A Sequential extraction of copper from lake sediments along Line E, Capoose Lake ...................... 222 55B Sequential extraction of zinc from lake sediments along Line E, Capoose Lake ......................223 55C Sequential extraction of iron from lake sediments along Line E, Capoose Lake ...................... 224 55D Sequential extraction of manganese from lake sediments along Line E, Capoose Lake ............ 225 x x i i 55E Sequential extraction of molybdenum from lake sediments along Line E, Capoose Lake ............226 56A Sequential extraction of copper from lake sediments along Line G, Capoose Lake ...................... 227 56E Sequential extraction of zinc from lake sediments along Line G, Capoose Lake 228 56C Sequential extraction of ir o n from lake sediments along Line G, Capoose Lake ...................... 229 56D Sequential extraction of manganese from lake sediments along Line G, Capoose Lake ............ 230 56E Sequential extraction of molybdenum from lake sediments along Line G, Capoose Lake •...•.,..... 231 57 O f f i c i a l and u n o f f i c i a l l o c a l e names of the Fish Lake - Portnoy Lake area ........................ 256 58 Geological map of the Fish Lake - Portnoy Lake area (after Bio Tinto, 1969) ......................... 258 59 Sample locations at Fish and Portnoy Lakes described i n text ...............................264 60A Distribution of copper values greater than 50 ppm i n s o i l s (courtesy Bio Tinto) •.... ... ............. 265 60E Distribution of molybdenum values greater than 5 or 50 ppm i n s o i l s (courtesy Bio Tinto) ............ 266 61A Variation of copper (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n , Lines 6 and 7 ..... 268 61E Variation of zinc (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Lines 6 and 7 .....269 61C Variation of molybdenum (ppm) i n s o i l s across the landscape, -80 mesh f r a c t i o n . Lines 6 and 7 .....270 x x i i i 62fl Portnoy camp - copper (ppb) i n stream Mater ..,,...273 62B Portnoy camp - copper (ppm) i n stream sediments, -80 mesh f r a c t i o n ....•...•.•...............•,...274 62C Portnoy camp - copper (ppm) i n top of the "B w s o i l horizon, -80 mesh f r a c t i o n ...................... 275 63A Portnoy camp - zinc (ppb) i n stream water ..,.,,,..276 63B Portnoy camp - zinc - (ppm) i n stream sediments, -80 mesh f r a c t i o n .............•.........•..,........ 277 64A Portnoy camp - molybdennm (ppb) i n stream water ...278 64B Portnoy camp - molybdenum (ppm) i n stream sediments, -80 mesh f r a c t i o n .................... 279 64C Portnoy camp - molybdenum (ppm) i n top of the MB" s o i l horizon, -80 mesh f r a c t i o n • 280 65 Trace element content (ppm) i n lake/stream sediment and organic matter i n lake sediment from Fish lake, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c a c i d attack ..................... , 282 66 Trace element content (ppb) i n lake/stream water from Fish Lake ..................................283 67 Trace element content i n lake sediment (ppm) and lake water (ppb) along Line N8, Fish Lake .,.,,..285 68 Trace element content i n lake sediment (ppm) and lake water (ppb) along Line SE, Fish Lake .......286 69 Trace element content (ppm) i n lake/stream sediment and organic matter i n lake sediment from Portnoy Lake, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c a c i d attack . ......„ .................... ......... ,...294 70 Trace element content (ppb) i n lake/stream water xxiv from Portnoy Lake ............................... 295 71 Trace element content i n lake sediment (ppm) and lake water (ppb) along Lines S, N, Portnoy Lake .296 72 Dispersion of Zn, Co, Mn, (Zn/Mn) x 100 i n lake sediments (frcm Coker and Nichol, 1975) .........313 73 Zn, Pb and Cu content of lake sediments from Trousers Lake, Quebec (from Schmidt, 1956) .,,...314 74 Zn, Pb and Cu content of lake sediments from Upsalguitch Lake, New Brunswick (from Schmidt, 1956) .. .... . . i-v ...... . . .... . . i . . 315 75 Zn, Pb and Cu content of lake sediments from Dore Lake, Quebec (from Schmidt, 1956) ...............317 76 Cu and Zn versus organic matter, Fe and Mn i n northwest Ontario area (from Nichol et a l , 1975) 319 77 Relation between organic carbon and water depth (from Coker and Nichol, 1S75) .......,.v.........320 XXV ACKNOWLEDGEMENTS The author i s grateful to many individuals who contributed to t h i s t h e s i s . F i e l d assistance was provided by Mr. J. Chatupa, Br. A. ,0. Ouellette, and Mr. M. J. Haskett-Myers i n 1971 and 1972.:Special thanks i s offered Mr. A. Troup of Bio Tinto Canadian Exploration Limited for assistance during both f i e l d seasons, and f o r subsequent discussions which aided i n int e r p r e t a t i o n of the geochemical r e s u l t s of these studies. In addition to the author, a n a l y t i c a l determinations were performed by Miss A. Baxters Mr. P. M. Arnold, Mr.,A. S. Dhillon, Mr. Gi Seid and Mr. M. J. Baskett-Myers. Assistance for thesis preparation was given by Mr. B. T. Arnold, Mr. S. Y. Chan, Mr. P. T. Midgley and Mri M. J . Jiaskett-Myers. Special thanks are offered to Dr. M. A. Barnes, Dr. E. V. G r i l l , Dr. L. M. Lavkulich, Mr. B. E. Lett, Dr. A. J . S i n c l a i r , and Dr. fl. V. Harren for c r i t i c a l examination of t h i s manuscript, or for constructive c r i t i c i s m s of experimental procedures, and to Dr.,W. K. Fletcher f o r his supervision of t h i s study. The author i s indepted to the management and s t a f f of Bio Tinto Canadian Exploration Limited who generously provided funding, and the a n a l y t i c a l data and reconnaissance samples of t h i s study. The thes i s was supported by a National Besearch Council of Canada Centennial Scholarship during 1972 and 1973. 1 CHftPTEB 1 INTBODUCTION TO LAKE SEDIMENT GEQCE EMISTRY. I STATEMENT OF THE PROBLEM Stream sediment samples are considered representative of the average trace metal content of a drainage basin, and are the basis of many reconnaissance geochemical exploration surveys. However i n some areas stream sampling i s not p r a c t i c a l because of poorly developed drainage systems, or because of d i f f i c u l t i e s i n obtaining samples. By contrast, lakes are often e a s i l y reached by float-eguipped a i r c r a f t . Moreover, by virtue of the i r position i n depressions i n the landscape, lakes act as traps f o r mechanical and chemical leads carried by streams and groundwater. Consequently, lake trace element leve l s should also r e f l e c t element d i s t r i b u t i o n s i n rocks within a catchment area. leathering of metal-rich or mineralized bedrock releases Cu, Zn, Mo, and other trace elements to the overburden i n soluble form or as c l a s t i c p a r t i c l e s . These are transferred to overlying s o i l , and are also dispersed downslope i n streams and groundwater. Metals subsequently are trapped i n the lakes and can accumulate to high l e v e l s . One of the aims or thi s thesis i s to investigate the relationship between mineral occurrences i n drainage basins of the Nechako plateau and lake sediment anomalies. However limnological processes can mask potential lake sediment anomalies, or give r i s e to f a l s e anomalies. Physical parameters of the lake, such as i t s shape, area, f e t c h , depth, bottom topography and currents, partly control lake 2 sediment trace metal content by a f f e c t i n g the r e l a t i v e proportions of sand, s i l t and clay that make up the sediment. Because sand i s usually metal-deficient r e l a t i v e to organic matter, amorphous Fe and Mn oxides and clay minerals, trace metal l e v e l s of sand-rich sediment are commonly lower than metal contents of finely-textured sediment (oozes) containing r e l a t i v e l y high concentrations of scavenging agents. A second aim of t h i s thesis i s to establish the importance of limnological processes i n modifying trace metal d i s t r i b u t i o n s i n proximity to mineralized bedrock. II FACTORS AFFECTING METAL CONTENT OF 1AKE SEDIMENTS Reconnaissance lake sediment surveys may rapidly and inexpensively assess the mineral potential o f a region. However th e i r application to exploration has been investigated vigorously only since 1970. Prior to pioneering papers i n North America by Schmidt (1956) and Arnold (1970) , studies were undertaken by limnologists ( e . g . Hutchinson, 1957). Generally, inte r e s t has centred on lake physical (Mortimer, 1949) or b i o l o g i c a l (Gorham et a l , 1974) properties. Chemical studies commonly were r e s t r i c t e d to the most abundant anions and cations (Brunskill and Ludlam, 1969) and, with a few exceptions, systematic studies of minor elements were not undertaken. In recent years, both environmental monitoring studies and investigations of the a p p l i c a b i l i t y of lake sampling to mineral exploration have expanded our knowledge of trace element behaviour i n lakes. Timperley and Allan (1974) have proposed a model r e l a t i n g rtetal 1ons released by weathering directly Into stream water are mainly complexed to colloids or to low molecular weight organic molecules. Mechanical weathering releases sulphide particles directly into «the stream. Oxidation of sulphides releases metal Ions, the majority of which are fixed onto clays and humus. Leaching by humic acids Is main mechanism of transport. /fc Silt and large clay particles fl\ settle. Dispersion In the lake Organo-clay colloids flocculate, coagulate and settle. Transport of primary and secondary minerals, organic and inorganic collolds.soluble complexes and metal tons. Heavy particles settle I.e. sands and si l ts . Iron and manganese oxide films and silicate 1on exchange are the predominant agents of metal accumulation. Basis of stream sediment geochemistry. , . , , . . Sands, silts and clays retain iron and manganese oxide coatings and occluded metals. Ions also retained on exchange sites on clays and other silicates. .Iron and manganese oxides dissolve releasing occluded ions. These ions as well as those on exchange sites precipitate as sulphides or complex to organic material. Soluble metal-organic complexes remain In solution or are assimilated by algae and plankton. Copreclpltatton of ions from solution with iron and manganese hydrous oxides. Formation of ferromanganese precipitates. Chemical and mechanical weathering directly into lake water. 1 chemical toeailiefi'*%<^ oncL Lake water turnover. Ions and complexes 1n the hypolimnlon are recycled into the epilimnlon where some copreclpltation of trace metals with iron and manganese oxides occurs. SULPHIDE MINERALS Very l i t t le metal 1on H e U l s c a n p iexed to organo-clay dispersion from underground c o l , o 1 < i s M y b e s U b , e o r m y sulphides unless the ground d i s s o c t a t e t 0 f o r m m e t a l s u i p hides. water is oxidizing. Decay of plankton and algae releases ions and complexes. Result may be metal sulphide precipitation or organic complexlng. F I G U R E 1 : M O D E L R E L A T I N G I N P U T S A N D D E P O S I T I O N O F T R A C E M E T A L S I N L A K E B A S I N S ( M O D I F I E D A F T E R T I M P E R L E Y A N D A L L A N / 1 9 7 4 4 trace metal content of lakes to a chemical balance between input and outflow of suspended or dissolved material (Pig 1). Metals released from bedrock or overburden enter the drainage network attached to s o l i d p a r t i c l e s or as i o n i c or complexed soluble species. The r e l a t i v e proportions of each transported to a pa r t i c u l a r lake depend on geologic, geomorphologic, pedologic, topographic and c l i m a t i c conditions of the surrounding drainage basin. Despite the fa c t that two lakes may be similar i n s i z e , shape, depth and r e l a t i v e landscape position, limnological factors may modify d i s t r i b u t i o n s of trace elements related to streams or groundwater deposition. Consequently, lake sediment anomalies do not necessarily form i n response to mineralized or metal-rich bedrock i n a watershed, though such units are a c t i v e l y discharging abnormal amounts of trace elements. Conversely, an element may accumulate to abnormally high l e v e l s despite only regionally average concentrations of the metal i n bedrock i n a catchment area. Factors such as lake environment or sediment texture and composition must be c a r e f u l l y assessed i n anomaly evaluation i n order to avoid misinterpretation of anomaly genesis. The most obvious input to a lake i s suspended or dissolved loads c a r r i e d by streams. Heavy grains s e t t l e near s i t e s of inflcw to form deltas. Nearshore sediment i s also commonly r i c h i n sand and gravel as a consequence of bank erosion around lake margins and wave winnowing of f i n e s . By contrast s i l t , clay and f i n e l y - d i v i d e d organic matter are transported greater distances in t o a lake and s e t t l e near the lake centre (Mortimer, 1949; Prink, 1969; Schoettle and Friedman, 1973). 5 Accumulation of sand and gravel i n shallow water environments, and f i n e l y - d i v i d e d material i n deeper parts of the lake i s considered a •normal 1 sediment te x t u r a l gradation. However sediment texture and composition may r e f l e c t large streams entering r e l a t i v e l y small lakes. In that case, the lake i s flushed r a p i d l y , and metal content of i t s sediment i s l i k e l y to r e f l e c t inflowing stream sediment l e v e l s (Rawson, 1960; Gorham et a l , 1974). Normal t e x t u r a l gradations are also modified by t u r b i d i t y currents, possibly i n i t i a t e d by an increase i n bank or shore erosion, or by slumping of foreset beds of deltas (Ludlam, 1974). , S i m i l a r l y , sand and woody fragments, rapi d l y introduced during flood periods, may be postulated as a major short term factor a f f e c t i n g sediment texture near the middle of the lake. Turbulent currents acting below wave base are less s i g n i f i c a n t but are nevertheless an important factor (Clark and Bryscn* 1959) which may either arrest s e t t l i n g of particulates (Schoettle and Friedman, 1973), or mix recent muds with lake bottom parent material (Thomas et a l , 1973). An absence of recent sediment can favour accumulation of Fe and Mn oxides (includes sesgui- and dioxides, both i n various stages of hydration) (Schoettle and Friedman, 1973) which, because of t h e i r scavenging a b i l i t y for trace metals, may p r e f e r e n t i a l l y concentrate trace elements r e l a t i v e to other nearby sediments. Organic matter has been studied more intensively than most of the other f r a c t i o n s comprising lake sediment. Organic matter i s derived from t e r r e s t i a l , p a r t i a l l y decomposed t e r r e s t i a l , and planktonic sources, each of which i s presumably associated with 6 a d i s t i n c t i v e suite of trace element l e v e l s . Undecomposed vegetation, mechanically introduced to a lake, would be expected to contain a d i f f e r e n t amount of trace elements than soluble humic acid complexes. The l a t t e r , released i n the watershed by decay of vegetation and pedogenesis, appears p a r t i c u l a r l y e f f e c t i v e i n leaching trace metals from s o i l s (Bashid, 1972), and from decaying leaf l i t t e r (Kimball, 1974). Algal and plankton materials produced within a lake are also important i n trace element c y c l i n g , and contain trace element suites which are distinguishable from land-derived organic matter. Thus c l a s s i f i c a t i o n of organic material i n t o recognizable classes on the basis of an allochthonous or autochthonous source (Sanger and Gorham, 1970) may reduce v a r i a b i l i t y attributable to provenance, and may aid i n d i f f e r e n t i a t i n g metal enrichment r e f l e c t i n g a peculiar variety of organic matter r i c h i n one or more elements. A s i m i l a r discussion has been presented by Hackereth (1966) on the o r i g i n * mode of introduction and accumulation, and properties of the Fe oxide f r a c t i o n . Mechanical inputs and physical s i z e - s o r t i n g processes are r e a d i l y observable features of lakes. Nevertheless metals introduced as soluble ions and complexes i n runoff (Timperley and Allan, 1974) or groundwater (Brunskill and Harriss, 1969; Mehrtens et a l , 1973) may also exert a s i g n i f i c a n t influence on trace element patterns, p a r t i c u l a r l y i n lakes having no s i g n i f i c a n t stream inflow. Cu, Zn and other elements are extracted from lake water by humic and f u l v i c acid f l o c c u l a t i o n , a l g a l and plankton a s s i m i l a t i o n , coprecipitation with or adsorption onto hydrous Fe and Mn oxides, and by adsorption onto 7 clay mineral surfaces. Removal of metal from water by adsorption onto p a r t i c u l a t e organic matter, or by assimilation by algae i s very important i n some lakes (Sanger and Gorham, 1970), and depends on the character of available organic molecules (Schindler et a l , 1972) . Genera of plankton may also a f f e c t metal uptake (Parker and Hassler, 1969; Bachmann and Odura, 1960; Knauer and Martin, 1973) . i i t h i n o l igotrophic lakes (low N, P, and nutrient sources and high dissolved oxygen content), b i o l o g i c a l productivity i s low, and by contrast to eutrophic lakes (high H, P, and nutrient sources and low dissolved oxygen content), deposition of s i g n i f i c a n t guantities of organic matter i s un l i k e l y . However despite enhanced deposition of organic matter i n eutrophic lakes, great productivity may r e s u l t i n high l e v e l s of organic matter d i l u t i n g trace element contents i n sediment, p a r t i c u l a r l y for sediments comprised primarily of organic constituents (Garrett and Davenport, 1976). Trace elements also can be extracted from lake water by p r e c i p i t a t i o n of a sulphide phase (Timperley and A l l a n , 1974). However, sulphide p r e c i p i t a t i o n i s probably not independent of b i o l o g i c a l a c t i v i t y . : Plankton growth consumes dissolved oxygen, and f a c i l i t a t e s b a c t e r i a l reduction of sulphate ions to sulphide ions (Gorham, 1960). Matson (1968) reports that a substantial lowering of i o n i c l e v e l s of trace elements occurs several days prior to an a l g a l bloom. Though cause of t h i s reduction remains unexplained, possible explanations include: formation of soluble metal-organic matter complexes, assimilation of metal by plankton, adsorption onto particulate organic matter and Fe and 8 Mn oxides, and p r e c i p i t a t i o n of metal sulphides. Many chemical reactions depend on the oxygen content of lake water. Mortimer (1949) outlined a model r e l a t i n g seasonal fluctuations i n water temperature to v a r i a b i l i t y i n oxidation potential of lake water and sediment. Following convective overturn of lake water i n spring or f a l l , the epilimnion (surface water) either heats or cools and becomes less dense than the hypolimnion (bottom water). Oxygen i n the hypolimnion i s s l o n l y consumed i n the decay of organic matter, and cannot be replenished from the atmosphere because of a density s t r a t i f i c a t i o n . In some lakes oxygen i s completely exhausted, and r e s u l t i n g reducing conditions i n i t i a t e chemical reactions, such as the transformation of i r o n from f e r r i c to ferrous form. Reduction of Fe and Mn to the divalent state i s rarely complete, and a f r a c t i o n of these metals remains in higher oxidation states as hydrated oxide phases (Coey et a l , 1974) , r e t a i n i n g adsorbed trace metals. Despite emphasis placed on sulphide p r e c i p i t a t i o n by Timperley and Allan (1974), p r e c i p i t a t i o n of hydrous Fe and Mn oxides following convective overturns i s undoubtedly a more important factor i n extraction and deposition of minor elements i n many lakes (Gorham, 1958; Horne and Woernle, 1972). I n i t i a l l y , f i n e l y suspended oxides are precipitated within the body of a lake* Newly-formed gelatinous precipitates incorporate other metals prior to s e t t l i n g to the lake f l o o r . Following sedimentation, precipitates are subjected to a variety of oxidation - reduction reactions which tend to either increase the c r y s t a l l i n i t y of the Fe and Mn compounds or cause t h e i r 9 d i s s o l u t i o n . Scavenged elements either become moire strongly incorporated within the oxide structure, or are released as soluble ions. I f l i b e r a t e d , metal ions can react with other sediment constituents or dissipate i n overlying water. In large lakes Fe and Mn oxide accumulation i s favoured by an absence of c l a s t i c inputs (Gorham and Swaine, 1965; Schoettle and Friedman, 1973; Thomas et a l , 1973). Concentration of Fe and Mn oxides may also f o l i o s oxidation of species migrating within diagenetic solutions, and lead to Fe and Mn enrichment near the sediment - water interface (Mothersill and Fung, 1972; Mothersill and Shegelski, 1973); However Fe and Mn oxides may not be a prominent constituent of sediment i n small lakes where organic matter deposition i s rapid, and a reducing environment i s maintained along the lake f l o o r most of the year. Other models are therefore necessary to explain trace element accumulation patterns. Berner (1969) proposed that under reducing conditions t y p i c a l of organic-rich lakes, ferrous, sulphide and other reduced ions migrate within diagenetic solutions u n t i l a counter ion i s found and p r e c i p i t a t i o n occurs. Mackinawite (FeS) or gre i g i t e (Fe3S^-)- i s produced most commonly, and gives the sediment a greenish-grey colour (Dcyle, 1968) . Although not considered by Berner (1969), trace elements presumably also are immobilized as sulphides (Timperley and Allan, 1974). Studies of lake sediment geochemistry are s t i l l i n t h e i r infancy. Detailed sampling of i n d i v i d u a l lakes i s necessary to e s t a b l i s h the degree of organic matter, Fe and Mn oxide, and trace element homogeneity within a lake basin. Influence of 10 sediment composition i n spuriously enhancing or reducing metal concentrations of lake sediments must be recognized to ensure that lake sediment anomalies r e f l e c t i n g mineralized bedrock can be c l e a r l y distinguished from limnological enhancements. Table I summarizes some of the factors which a f f e c t composition of lake sediment, and i n d i r e c t l y influence lake sediment trace metal l e v e l s . I l l HISTORY OF LIKE SEDIMENT GEOCHEMISTRY APPLIED TO MINEBAL EXPLORATION Although anomalous stream sediment dispersion t r a i n s are often terminated upon entry into a lake, and both Schmidt (1956) and Arnold (1970} demonstrated that trace element content of lake sediments r e f l e c t s proximity to mineralized bedrock, Allan (1971) was the f i r s t to report r e s u l t s of a regional geochemical lake sediment sampling program. His study, in the permafrost environment of the Coppermine River area, N. H. „• T., involved c o l l e c t i o n of inorganic* nearshore sediment at a density of one sample per 25 km2w The survey outlined the Coppermine River basalt, a unit which contains numerous copper showings and one major deposit. In regional surveys by Allan and h i s coworkers for the Geological Survey of Canada (Allan et a l , 1972a; 1972b; 1973a; 1973b), sample c o l l e c t i o n was r e s t r i c t e d to nearshore inorganic sediment i n inflow and outflow bays on the premise that these areas contain s i m i l a r trace metal concentrations to adjacent stream sediments, and hence are d i r e c t l y r e l a t e d to catchment material (Dyck, 1971). Sampling in shallow water of the nearshore environment by impressing a p l a s t i c or metal tube into the lake f l o o r i s also amenable to rapid c o l l e c t i o n 1 1 T a b l e I Summary o f w a t e r s h e d , l a k e and sediment parameters l i k e l y t o s t r o n g l y i n f l u e n c e t r a c e m etal l e v e l s o f l a k e s e d i m e n t s WATERSHED CHARACTERISTICS LAKE PHYSICAL PARAMETERS LAKE SEDIMENT PROPERTIES 1. C l i a a t e 1. Lake a r e a and shape 1. Saaple homogeneity 2. Topography 2. Haxiaua l a k e l e n g t h 2. C o n s i s t e n c y - s a a p l e water c o n t e n t 3. Lake e l e v a t i o n 3. Maximum l a k e width 3. O x i d i z e d o r reduced aud a. Geology 4. Lakeshore c h a r a c t e r - 4. S e s q u i o x i d e c o n t e n t and boggy v e r s u s sandy c o n c r e t i o n s s. S u r f i c i a l d e p o s i t s 5. Lake s h o r e l e n g t h 5. Organic n a t t e r d e c o a p o s i t i o n 6. watershed a r e a 6. D i s t r i b u t i o n o f i s l a n d s 6. A n c i e n t b o t t o a sediment 7. Types and e x t e n t o f 7. Number o f major and minor 7. D e l t a i c sands o r g r a v e l s v e g e t a t i v e c o v e r i n f l o w i n g streams and p r o x i a i t y t o s a a p l e s i t e 8. S o i l s 8. P r o x i m i t y of s a a p l e s i t e 8. Nearshore sands or g r a v e l s t o o u t f l o w 9. E x t e n t of f l a s h i n g 9. Lake water c o l o u r 9. T u r b i d i t e s 10. 10. 10. A l g a l s a t 11. 11. 11. B e n t h i c v e g e t a t i o n 12. 12. 12. Calcium c a r b o n a t e 13. , 3 ' 13. S h e l l f r a g a e n t s 14. 14. 14. Hydrogen s u l p h i d e odour - — 12 procedures. However, i n c l i m a t i c zones where trees l i n e the shore and inorganic sediment i s rare, t h i s sampling technique may not be practical.,. Hesults of subsequent regional surveys by Allan et a l (1973a) i n the Bear and Slave provinces, H. H., I., and by Dyck (1974) i n the Beaverlodge d i s t r i c t , Saskatchewan, confirmed that lake sediment geochemistry was e f f e c t i v e i n indicating areas of trace metal enrichment related to mineralized bedrock or metal-r i c h l i t h o l o g i e s . The survey by Allan also resulted i n the discovery of a Pb - Zn - Cu - Ag prospect associated with a gossan zone i n volcanic t e r r a i n (Hichol, 1975). S i m i l a r l y , Hoffman and Fletcher (1972) found that the Bayfield Biver syenite stock (south-central B r i t i s h Columbia), containing bornite and chalcopyrite disseminated along fractures, was associated with regionally enhanced Cu l e v e l s i n lake sediments. Further, a correspondence was found between the highest Cu grades i n bedrock and the maximum Cu content i n lake sediment. Workers i n temperate climates have assumed that the grey-green, water-saturated, f i n e l y - d i v i d e d ooze, which i s referred to as gyttja (Timperley and A l l a n , 1974) , i s homogeneous and representative of trace metal content of a drainage basin (Davenport et a l , 1975). Sample r e t r i e v a l from the centre of the lake also avoids shoreline influences. Because lake depths near the middle of a lake may be great, sampling devices capable of reaching several tens of metres, such as a * mud snapper•, Ekman-Birge dredge* or Phleger corer are required. Despite increased d i f f i c u l t y of sample c o l l e c t i o n over nearshore programs, surveys have attained a f a i r degree of success and 13 have proven to be economically viable (Nichol, 1975)., Davenport et a l (1975) were able to define several Zn-rich zones overlying favourable limestone formations i n western Newfoundland. Mehrtens et a l (1973) found enhanced Mo le v e l s i n lake sediments downslope from a molybdenite occurrence i n the central i n t e r i o r of B r i t i s h Columbia. Despite the record of several successes, i n t e r p r e t a t i o n of lake sediment data can present problems. Trace metal d i s t r i b u t i o n s obtained from analysis of organic-rich sediment may f a i l to pinpoint known mineral occurrences, coker and Nichol (1975),extending the study of lake sediment geochemistry to the southern Canadian Shield i n Ontario, were unable to confirm mineralized areas as anomalous unless they considered Zn/Mn and Ni/Hn r a t i o s . This was attributed to the scavenging e f f e c t of hydrous Fe and Mn oxides for Zn and Ni. Gleeson and Hornbrook (1975) encountered a d i f f e r e n t type of problem i n r e l a t i n g metal content of lake sediment with mineralized ultramafic bodies. In their case, absence of a lake sediment anomaly appeared to r e s u l t from deep g l a c i a l overburden acting as a barr i e r to secondary dispersion. However basal t i l l sampling was e f f e c t i v e . Numerous workers employ regression analysis to assess influence of sediment composition on trace metal l e v e l s . Allan et a l (1973a) and Dyck (1974) suggest regression analysis be used to reduce v a r i a b i l i t y related to scavenging by organic matter. Spilsbury and Fletcher (1974) found a negative c o r r e l a t i o n between Cu and Zn l e v e l s and the sand content of nearshore sediment. In that study quartz and feldspar minerals 14 comprising the sand f r a c t i o n are impoverished i n Cu and Zn r e l a t i v e to clay minerals or Fe and Mn oxides. Davenport et a l (1975) and others have also found regression analysis to be useful i n enhancing contrast through reduction of v a r i a b i l i t y caused by l i m n c l o g i c a l factors. IV SUMMARY lake sediment anomalies can r e f l e c t either mineralized bedrock (or metal-rich l i t h o l o g i e s ) within a catchment area, or spurious enrichment caused by Fe and Mn oxide scavenging, organic matter scavenging, or other factors. Of p a r t i c u l a r concern i s the recognition of those trace element enrichment patterns related to mineralized bedrock. ,; However because sediment properties and limnological environments vary considerably within a lake, metal accumulation zones may be r e s t r i c t e d to small areas along the lake f l o o r . In addition, factors such as scavenging, d i l u t i o n , sedimentation rates, emergence of groundwater, and oxidation - reduction reactions can complicate trace element d i s t r i b u t i o n s . Consequently, for successful application of lake sediment sampling to exploration, problems introduced by these li m n c l o g i c a l factors must be recognized at an early stage of a survey to ensure that spurious values do not overide regional trends. A number of reconnaissance lake sediment programs have indicated that trace metal l e v e l s r e f l e c t the anomalous character of a catchment area. Nevertheless cases e x i s t where abnormal concentrations of metal i n lakes cannot be a t t r i b u t e d to metal-rich or mineralized bedrock; examples may also be c i t e d 15 where recognized mineral showings are not r e f l e c t e d i n nearby lakes. For some surveys d e f i n i t i o n of anomalies may be resolved by employing s t a t i s t i c a l techniques such as regression analysis. Despite possible i n t e r p r e t a t i v e d i f f i c u l t i e s , lake sediment sampling i s an a t t r a c t i v e procedure for rapid mineral p o t e n t i a l evaluation i n remote or tree-covered areas. 16 C H A P T E R 2 DESCRIPTION OF THE STUD* AREA I LOCATION AND ACCESS The Nechako plateau i s a physiographic subdivision of the Int e r i o r Plateau and l i e s in north-central B r i t i s h Columbia (Fig 2). Limited access i s provided by gravel roads from the Cariboo Highway (Highway 97) at Prince George or Highway 16 i n the north. Secondary routes extend frcm Vanderhoof to the Kenny Dam and Prince George to Batanuni Lake along the Blackwater River. Otherwise, float-equipped fixed-wing a i r c r a f t or he l i c o p t e r s are required to reach most areas. II REGIONAL GEOLOGY (Fig 3) Regional geology has been described by Tipper (1961, 1963). Poorly exposed sequences of Paleozoic chert, a r g i i l i t e and limestone, with minor interbedded mafic volcanics of the Cache Creek group, form a belt along the eastern margin of the study area. These are intruded by serpentinized peridotites, with surface exposures varying from single outcrops to 65 km2. Relationships between these units and younger rocks are unclear because extensive g l a c i a l deposits conceal the geology. It i s postulated that a period of volcanism followed the ultramafic plutonism, depositing Late T r i a s s i c or Early Jurassic Takla group submarine andesite and basalt flows, t u f f s and breccias intercalated with a r g i l l i t e s and minor limestone. The succeeding Hazelton group i s composed of sim i l a r rock types but includes a greater proportion of sedimentary units. These LEGEND Mojor town Q Entfako Mo mint •j^- Mineral prospect •>••••> Rivrr, mojor slrtam """* Highway Secondary rood Railway F I G U R E 2 : L O C A T I O N O F A N D A C C E S S ON T H E N E C H A K O P L A T E A U , C E N T R A L B R I T I S H C O L U M B I A 1 8 G E O L O G I C A L L E G E N D I O V E R B U R D E N ( M I N O R O U T L I E R S O F T H E C A C H E C R E E K G R O U P A R E N O T D I F F E R E N T I A T E D I N T H E E A S T ) 111 E N D A K O G R O U P V O L C A N I C S = O O T S A L A K E G R O U P V O L C A N I C S _B_ J U R A S S I C / C R E T A C E O U S I N T R U S I O N S zzz H A Z E L T O N G R O U P V O L C A N I C S A _ T O P L E Y I N T R U S I O N S Ii T A K L A G R O U P V O L C A N I C S U l S E R P E N T I N I Z E D P E R I D O T I T E F I G U R E 3 : R E G I O N A L G E O L O G Y O F T H E N E C H A K O P L A T E A U ( T I P P E R , 1 9 6 1 , 1 9 6 3 ) 19 subaqueous units form part of a sequence of volcanic rocks within the Intermontane Belt (Sutherland-Brown et a l , 1971) considered favourable for Cu, Pb and Zn occurrences (Lord, 1948; Boots, 1954; and Tipper, 1963). During Cretaceous and Tertiary times they were overlain by a widespread cover of subaerial volcanic rocks of variable thickness (Tipper, 1974), forming the Ootsa Lake (basalt, andesite, r h y o l i t e , dacite, related t u f f s and breccias) and Endako groups (vesicular and amygdaloidal andesite and basalt, flow breccia, t u f f , conglomerate, greywacke and l i g n i t e ) . In the north, volcanic t e r r a i n has been intruded by granite, granodiorite, d i o r i t e and quartz d i o r i t e of the Early Jurassic Topley intr u s i o n s , and i n the southwest by s i m i l a r Late Jurassic and/or Cretaceous plutons. Located 8 km from the northwest quarter of the study area (Fig 2), the Endako molybdenum mine (188.5 million tons grading 0.143% MoS2, Dec 1972), l i e s within Topley bedrock. Numerous Mo prospects i n the Nithi H i l l s (northwest corner of the study area. F i g 2) are also recognized within the Topley. Consequently, the unit i s considered favourable for molybdenum occurrences. However, despite the many showings of molybdenite, no prospect with mining potential has been found other than the Endako deposit. During the Pleistocene the Nechako plateau was overridden by an i c e sheet moving i n a northeasterly to easterly d i r e c t i o n (Tipper, 1971)i of s u f f i c i e n t thickness to flow over mountain ranges without appreciable deflection. Near the end of the Pleistocene the i c e cover was reduced by a combination of ql a c i e r retreat and stagnation. Glacier breakup i s believed to 20 have been topographically controlled, and resulted i n i s o l a t e d ice blocks wasting i n s i t u to form ablation moraine. These deposits, characterized by an i r r e g u l a r , hummocky surface of low r e l i e f , surround the Fawnie and Nechako Ranges. In contrast, drumlin f i e l d s are common i n areas of thick g l a c i a l overburden to the north and west and regions underlain by Endako basalt. In the f i n a l stages of deglaciation, meltwater streams dissected t i l l and bedrock to deposit sediment i n outwash and p i t t e d outwash plains. I I I CLIMATE The Nechako plateau has a continental climate, with short warm summers (maximum 31°C) and long cold winters (minimum -40°C) . Annual p r e c i p i t a t i o n of 25 to 50 cm f a l l s mainly as r a i n during the summer months, although melting of mountain snow in spring and summer provides much of the yearly runoff. IV TOPOGRAPHY AND DRAINAGE Average lowland elevation of the Nechako plateau varies between 830 and 1000 a. Two prominent mountain ranges, the Fawnie and Nechako (Fig 2), reach 2000 m elevations and trend northwesterly across the west-central Nechako plateau. Elsewhere, i s o l a t e d groups of h i l l s r i s e as much as 500 m above the plateau proper* The Nechako plateau i s part of the Fraser River watershed. However many r i v e r s i n the west were diverted by the Kenny Dam to the P a c i f i c Ocean through the Kemano Tunnel, as part of the Kitimat power project completed i n 1952. Stream erosion i s most 21 active over the western two-thirds of the region due to greater l o c a l r e l i e f . A high density of drainage channels i s found i n the higher portions of the plateau i n contrast to the r e l a t i v e l y few and widely-spaced major r i v e r s which cross the lowlands. The l a t t e r , including the Ootsa, Entiako and Nechako Rivers, flow along broad v a l l e y s , and l o c a l l y become deeply entrenched. Smaller streams form a disorganized and i r r e g u l a r drainage network, and commonly are found within large bog-lake complexes i n low-lying areas between the mountains. Lakes and ponds range i n size from very large water bodies, such as Francois Lake and Natulkuz Lake, to small ponds with diameters measuring i n the tens of meters. : Large lakes are narrow and elongated, r e f l e c t i n g previous history of t h e i r basins as g l a c i a l or r i v e r valleys. C l a s t i c deposits along shore are common and bogs are rare. In contrast, small lakes are normally associated with large bogs or isol a t e d topographic depressions. Their development often stems from construction of beaver dams across stream channels. Two contrasting limnological environments are recognized. One i s characterized by large (>3 km long) cligotrophic lakes having water depths i n excess of 6 m, and a marked thermocline during summer months. Accumulation of s i l t and c l a y - r i c h sediment predominates near the middle of the lake. Organic matter accumulation amounts to l e s s than 10% by weight. Sediment consistency varies from water-charged oozes to firm muds, ranging i n colour from o l i v e (Hunsell colour 5Y4/4) through shades of brown to dark red (1QR3/6). Sand and gravel deposits are associated with wave erosion along shore, and with 2 2 d e l t a i c sedimentation of major inflowing streams. The second limnological environment i s exemplified by small dystrophic and eutrophic lakes which are associated with swampy areas of low r e l i e f . Lush aquatic vegetation i s abundant, p a r t i c u l a r l y reeds and sedges nearshore. These absorb wave energy, y i e l d large quantities of organic matter, and cause encroachment of bog c h a r a c t e r i s t i c s into the lakes. , Inflowing streams are t y p i c a l l y small and must cross low energy bogs i n which a l l but the most f i n e l y suspended material i s trapped prior to reaching the lake. Consequently lake sediment i s composed primarily of organic matter i n various stages of decay, and contains s n a i l s h e l l s , roots of agnatic plants, wood fragments and pre c i p i t a t e s of calcium carbonate. Sediments are best described as water-charged soupy to firm muds, varying from ol i v e (514/4) to brown (10YH4/4) to white colours. Thermoclines t y p i c a l l y f a i l to develop i n small lakes because shallow lake depths (<6 •) promote frequent overturns, although considerable temperature gradients develop with depth, wind-induced turbulence introduces oxygen to the lake f l o o r f o r most i c e - f r e e periods of the year. Oxygen may be nevertheless consumed with i n t e n s i f i c a t i o n of organic matter decomposition i n late summer, and reducing conditions commonly are i n i t i a t e d . Cooling i n f a l l and ice formation i n winter thermally s t r a t i f i e s lake water and may lead to anoxic conditions which can per s i s t u n t i l spring thaw. V SOILS AND VEGETATION S o i l genesis depends on the texture, water content, surface 2 3 slope, vegetative cover and age of l o c a l overburden. Many s o i l types are recognized, the more prominent of which are brunisols and podzols. although both s o i l types r e f l e c t leaching near the surface and accumulation of Fe and al sesguioxides i n the • B* horizon, podzols t y p i f y areas where slopes are steeper and/or overburden texture i s sandier than average. In other areas, clay translocation from the •a 1 to *B1 horizon i s important and r e s u l t s i n development of l u v i s o l s . Gleysols form i n areas of poorly-drained overburden which are subjected to reducing conditions most of the year, p a r t i c u l a r l y near bogs, seepage zones, and abrupt changes i n topographic slope. Gleysols p e r i o d i c a l l y dry and ferrous i r o n oxidizes to form diagnostic red-brown (7.5YB4/i») mottles. Bithin boggy areas, organic matter accumulates to form organic s o i l s composed of p a r t l y decayed grasses, mosses, sedges* reeds and l i t t e r from willows, brush and trees. apart from t h e i r i d e n t i f i c a t i o n , organic s o i l s are not c l a s s i f i e d f u rther. Begoscls develop on talus deposits i n the mountains and along deeply incised streams. They are also common i n association with recent a l l u v i a l deposits along the f l o o r s of major r i v e r valleys. S o i l c l a s s i f i c a t i o n i s based on i d e n t i f i c a t i o n of diagnostic properties of s o i l horizons, p a r t i c u l a r l y the top of the-•B* horizon; Four major v a r i e t i e s of •B* horizon are recognized. These are the *Bf', a red-brown mineral horizon r e f l e c t i n g Fe oxide accumulation and diagnostic of podzols; the • Bm*, a horizon only s l i g h t l y d i f f e r e n t i n colour from underlying parent material and commonly indicative of brunisols; the »Bt', a zone of clay enrichment t y p i c a l of l u v i s o l s ; and the 24 *Bg*# a mottled zone r e f l e c t i n g water-saturated conditions most of the year. A f i f t h designation, »Bh*, refers to a black, organic-rich mineral horizon l y i n g at depths greater than 15 cm. Absence of a »B' horizon may be the c r i t e r i o n used to define regosols. Cumulic character i s indicated by a l t e r n a t i n g partly decomposed organic material and unaltered mineral matter. Other s o i l horizons commonly encountered are the •L-H', a l e a f -humus organic-rich layer l y i n g on the ground surface, the 'Ah*, a dark grey to black organic-rich mineral horizon, the •Ae*, a l i g h t grey to brown leached mineral horizon, and the •C* horizon or parent material. A more detailed description of s o i l horizons and methods for th e i r i d e n t i f i c a t i o n are outlined in •The system of s o i l c l a s s i f i c a t i o n for Canada* (Canada Department of Agriculture, 1970). The region i s forested by lodgepole pine (Pinus contorta l a t i f o l i a ) . Trees r a r e l y reach 0.3 m i n diameter and therefore are not suitable for commercial log harvesting operations. Isolated stands of the i n t e r i o r variety of Douglas f i r (Pseudotsuga menziesii), aspen poplar (Populus tremulordes) and Engelmann spruce (Picea engelmanni) have also been observed. Black spruce (Picea ariana) are common along creek banks and at peripheries of bogs.; At higher elevations tree growth i s stunted by severe climate and dwarf growths predominate. These are displaced by grasses and alpine tundra above 1700 i . In wet areas along breaks i n slope and i n lake-bog complexes, vegetation i s composed of bog growths, including reeds, sedges, mosses, and willows., 25 CHAPTER 3 MINERAL EXPLORATION OF THE NECHAKO PLATEAU USING LAKE SEDIMENT GEOCHEMISTRY I RECONNAISSANCE SURVEY A. Introduction A lake sediment geochemical survey was completed during July and August;,- 1970, over 16,000 km2 of the Nechako pleateau to t e s t e f f i c i e n c y of the technigue i n regional exploration. One or more organic-rich sediments were collected near the centres of approximately 500 lakes (Fig 4) during a helicopter assisted survey, on the premise that t h i s f i n e l y - d i v i d e d material would he homogeneous and representative of catchment trace metal l e v e l s . B. Sample c o l l e c t i o n , preparation and analysis The reconnaissance lake sediment survey involved c o l l e c t i o n of 656 samples from approximately 500 lakes. Sediment was retrieved i n a mud snapper (Kahl S c i e n t i f i c Instruments, California) lowered from a f l o a t equipped helicopter. At least one sample, preferably of organic-rich, f i n e l y - d i v i d e d material was c o l l e c t e d from c e n t r a l portions of each lake. Sample lo c a t i o n , date, sediment colour, lake depth and vi s u a l estimates of the sand, clay and organic matter content were recorded. Lake sediments were oven dried (110°C) and disaggregated by pulverizing prior to chemical analysis. Trace element contents of reconnaissance lake sediment samples were determined by Rio Tinto Canadian Exploration Limited (Rio Tinto) using atomic absorption methods., A 1.0 g STUDY AREA. U T M N 598 oooo m UTM E 34 oooo m 36 * ..ANOMALY LOCATIONS 1 CAPOOSE LAKE 2 GREEN LAKE . 3 F I S H L A K E . PORTNOY LAKE 1 H ITHI H I LLS 5 CANOE LAKE 6 VERONICA LAKE 7 " HOGSBACK LAKE 8 BOBTAIL MOUNTAIN [88 CU GEOLOGICAL LEGEND OVERBURDEN (INCLUDES MINOR OUTLIERS OF CACHE CREEK GROUP TO EAST) ENDAKO GROUP VOLCANICS OOTSA LAKE GROUP VOLCANICS JURASSIC/CRETACEOUS INTRUSIONS HAZELTON cnoup VOLCANICS TOPLEY INTRUSIONS TAKLA GROUP VOLCANICS SNRPENTINIZED PER1D0TITE \ GEOCHEMICAL LEGEND • SAMPLE LOCATION 1 0 2 0 30KH SCALE ~~* FIGURE 4S SAMPLE LOCATION MAP, NECHAKO PLATEAU LAKE SEDIMENT SURVEY (GEOLOGY AFTER GEOLOGICAL SURVEY OF CANADA MAPS 1131A S 4 9 - 1 9 E 0 ) tsj 27 s p l i t of ground sample was digested to dryness with 10 ml of a 4:1 mixture of n i t r i c and perchloric ( n i t r i c / p e r c h l o r i c ) acids. Residues were extracted with d i l u t e hydrochloric acid, and analyzed f o r Cu, Ho, Hi, Pb, Zn, Mn, Ag and Co. Aluminum t r i c h l o r i d e (hexahydrate) was added to suppress interferences i n the atomic absorption determination of Mo (Kerbyson and Batzkowski, 1970); Cu, Ho, Fe; Mn, Pb and Zn were reanalyzed on a 100 sample subset following the OBC n i t r i c / p e r c h l o r i c acid procedure (Chapter 4, page 59). , Loss on i g n i t i o n (LOI) was determined i n conjunction with emission spectrometric analysis of Sr, Ba, Cr, Co; Ni, Ag, T i , Cu, In, ?, Mo; B i , Ga, Sn, Pb, Mn and Sb. An a l y t i c a l procedures and instrumentation are described further i n Chapter 4. C. Geochemical r e s u l t s 1 . Relationship between trace element d i s t r i b u t i o n s and geology The density d i s t r i b u t i o n s of Cu, Mo, Pb, Zn, Hi, Ga, Ba, Cr, Co, Sr, Ag and V i n lake sediments of the Nechako plateau were assumed to follow normal or lognormal laws. Histograms were constructed and elements were c l a s s i f i e d into lognormal (Ni, Pb, Zn, Mn, Cr, In), normal (LOI, Co), normal or lognormal (Cu, V) or other (Mo, Sr, Ba, Ga) d i s t r i b u t i o n s . Hean, range (defined as the i n t e r v a l from the mean (x) minus one standard deviation (cr) to the mean plus one standard deviation) , and threshold (>(x+2<r)) l e v e l s were calculated for normal and lognormal d i s t r i b u t i o n s and trace elements subsequently plotted according to a s i z e coded scheme whereby the larger the symbol, the greater the trace element concentration (Figs 5 to 9). STUDY AREA ft PRINCE 'GEORGE 7(t\ «p o <&° °*> »^ \W(COUVER UTM E 34 oooo m 3 6 A N O M A L Y L O C A T I O N S 1 C A P O O S E L A K E 2 G R E E N L A K E 3 F I S H L A K E . P O R T N O Y L A K E 1 M I T H I H I L L S 5 C A N O E L A K E 6 V E R O N I C A L A K E 7 H O G S B A C K L A K E 8 B O B T A I L M O U N T A I N UTM N "598oooom u G E O L O G I C A L L E G E N D O V E R B U R D E N ( I N C L U D E S M I N O R O U T L I E R S O F C A C H E C R E E K G R O U P TO E A S T ) E N D A K O G R O U P V O L C A N I C S O O T S A L A K E G R O U P V O L C A N I C S J U R A S S I C / C R E T A C E O U S I N T R U S I O N S H A Z E L T O N G R O U P V O L C A N I C S T O P L E Y I N T R U S I O N S T A K L A G R O U P V O L C A N I C S S E R P E N T I N I Z E D P E R I D O T I T E 4 6 4 8 G E O C H E M I C A L L E G E N D o L E S S T H A N 8 P . P . M . <(x - 2 • 58 - 151 P . P . M . (X+O -. (x+2<r) • 152 - 396 p.P . M . (x+2<r) - {x+?><*-) ® M O R E T H A N 396 P . P . M . >(x+3«~) 0. 10 20 30KM F I G U R E 5: N E C H A K O P L A T E A U L A K E S E D I M E N T S U R V E Y F O R N I C K E L ( G E O L O G Y A F T E R G E O L O G I C A L S U R V E Y O F C A N A D A M A P S 1131A 8' 49-1960) S C A L E 0 0 UTM E 34oooom 3 6 UTM N t 5 9 8 o o o o m * A N O M A L Y L O C A T I O N S . 1 C A P O O S E L A K E 2 G R E E N L A K E 3 F I S H L A K E , P O R T N O Y L A K E ii H I T H I H I L L S 5 C A N O E L A K E 6 V E R O N I C A L A K E 7 H O G S B A C K L A K E 8 B O B T A I L M O U N T A I N G E O L O G I C A L L E G E M ) O V E R B U R D E N ( I N C L U D E S M I N O R O U T L I E R S O F C A C H E C R E E K G R O U P TO E A S T ) E M D A K O G R O U P V O L C A N I C S O O T S A L A K E G R O U P V O L C A N I C S J U R A S S I C / C R E T A C E O U S I N T R U S I O N S H A Z E L T O N G R O U P V O L C A N I C S T O P L E Y I N T R U S I O N S T A K L A G R O U P V O L C A N I C S S E R P E N T I N I Z E D P E R I D O T I T E 46 48 G E O C H E M I C A L L E G E N D • 3 - 9 P . P . M . (x + «r) - (x+2<r) • 1 0 - 21 p.P.M. (x+2«r) - (x + 3<r) © M O R E T H A N 2<J p.P . M. >(x + 3«") 1 0 2 0 3 0 K M F I G U R E 6: N E C H A K O P L A T E A U L A K E S E D I M E N T S U R V E Y F O R M O L Y B D E N U M ( G E O L O G Y A F T E R G E O L O G I C A L S U R V E Y O F C A N A D A M A P S 1 1 3 1 A & 1 9 - 1 9 6 0 ) S C A L E to UTM E 34oooo m 36 •A- A N O M A L Y L O C A T I O N S 1 C A P O O S E L A K E 2 G R E E N L A K E 3 F I S H L A K E . P O R T N O Y L A K E 4 K I T H I H I L L S 5 C A N O E L A K E . 6 V E R O N I C A L A K E 7 H O G S B A C K L A K E 8 B O B T A I L M O U N T A I N UTM N "598 oooo m G E O L O G I C A L L E G E N D O V E R B U R D E N ( I N C L U D E S M I N O R O U T L I E R S O F C A C H E C R E E K G R O U P T O E A S T ) EMDAKO G R O U P V O L C A N I C S O O T S A L A K E G R O U P V O L C A N I C S J U R A S S I C / C R E T A C E O U S I N T R U S I O N S H A Z E L T O N G R O U P V O L C A N I C S T O P L E Y I N T R U S I O N S T A K L A G R O U P V O L C A N I C S S E R P E N T I N I Z E D P E R I D O T I T E 46 48 G E O C H E M I C A L L E G E N D • 43-95 p.P.M. « 96 - 210 P . P . M . (X+2<r) - (x + 3<r) O M 0 R E ™ A N 210 P . P . M . > ( X + 3°~) 0. 10 20 30KM F I G U R E 7: i .ECHA 'KO P L A T E A U L A K E S E D I M E N T S U R V E Y F O R C O P P E R ( G E O L O G Y A F T E R . G E O L O G I C A L S U R V E Y O F C A N A D A M A P S 1131A & 49-1960) S C A L E o STUDY AREA UTM E 34oooom 3 6 UTM N 598 oooom A N O M A L Y L O C A T I O N S 1 C A P O O S E L A K E 2 G R E E N L A K E 3 F I S H L A K E . P O R T N O Y L A K E 1 N I T H I H I L L S 5 C A N O E L A K E 6 V E R O N I C A L A K E 7 H O G S B A C K L A K E 8 B O B T A I L M O U N T A I N mn u G E O L O G I C A L L E G E N D O V E R B U R D E N ( I N C L U D E S M I N O R O U T L I E R S O F C A C H E C R E E K G R O U P TO E A S T ) E N D A K O G R O U P V O L C A N I C S O O T S A L A K E G R O U P V O L C A N I C S J U R A S S I C / C R E T A C E O U S I N T R U S I O N S H A Z E L T O N G R O U P V O L C A N I C S ToPLEY I N T R U S I O N S T A K L A G R O U P V O L C A N I C S S E R P E N T I N I Z E D P E R 1 D O T I T E 46 48 G E O C H E M I C A L L E G E N D • 2 - G P . P . M . (x + <r) - (x+2<r) • 7-17 P . P . M . . ( X + 2 0 - (x+3<r) © M O R E T H A N 17 P . P . M . >(x+3cr) • 10 20 30KM • F I G U R E 8S N E C H A K O P L A T E A U U K E S E D I M E N T S U R V E Y F O R L E A D ( G E O L O G Y A F T E R G E O L O G I C A L S U R V E Y O F C A N A D A M A P S 1131A £ 49-1960) S C A L E i — 1 STUDY AREA. UTM E 34 oooo m 36 •A- A N O M A L Y L O C A T I O N S 1 C A P O O S E L A K E 2 G R E E D L A K E 3 F I S H L A K E . P O R T N O Y L A K E 1 f i i TH i H I L L S 5 C A N O E L A K E 6 V E R O N I C A L A K E 7 H O G S B A C K L A K E 8 B O B T A I L M O U N T A I N > i i II [ j if-)jil I 1 ill 1 I' I I 16 38 40 42 UTM N "598 oooom 44 mi! G E O L O G I C A L L E G E N D O V E R B U R D E N ( I N C L U D E S M I N O R O U T L I E R S OF C A C H E C R E E K G R O U P TO E A S T ) E N D A K O G R O U P V O L C A N I C S O O T S A L A K E G R O U P V O L C A N I C S J U R A S S I C / C R E T A C E O U S I N T R U S I O N S H A Z E L T O N G R O U P V O L C A N I C S T O P L E Y I N T R U S I O N S T A K L A G R O U P V O L C A N I C S S E R P E N T I N I Z E D P E R I D O T I T E 46 48 G E O C H E M I C A L L E G E N D 98 - 237 p . P . M . (x+<r) - (x+2<) i 238 - 5 7 1 P . P . M . ( x + 2 0 - (x+3<r) • M O R E T H A N 5 7 1 p.P . M . ?(x+3^") 1 0 20 30KM F I G U R E 9: N E C H A K O P L A T E A U L A K E S E D I M E N T S U R V E Y F O R Z I N C ( G E O L O G Y A F T E R G E O L O G I C A L S U R V E Y O F C A N A D A M A P S 1 1 3 1 A & 1 9 - 1 9 6 0 ) S C A L E 33 Smallest symbols represent above average (x+r) values, although for Ni (Fig 5) , values below the negative threshold (x-2cr) are also indicated. Geology appears to control trace element l e v e l s associated with one or more of the f i v e major l i t h o l o g i e s of the plateau (Table I I ). Although an element may be concentrated to an unusually high l e v e l i n association with a s p e c i f i c rock type, i t i s commonly suites of element l e v e l s rather than i n d i v i d u a l element values that distinguish s u p e r f i c i a l l y similar geological units. For example Co and Zn-rich sediments are associated with Takla volcanics* whereas enhanced Sr, Ba and V lev e l s are associated with Hazelton rocks* S i m i l a r l y , Cr, Mi, and an values are progressively higher and Cu, No, and Pb lower following the seguence Takla, Hazelton and Tertiary volcanic rocks. Serpentinized peridotite bodies form isolated h i l l s r i s i n g up to 500 m above the general l e v e l of the eastern half of the plateau. Consequently they are not d i r e c t l y overlain by any lakes and hence are excluded from Table I I . Nevertheless one of the most s t r i k i n g relationships between lake sediment geochemistry and geology i s associated with these intrusions near Bobtail and Sinkut mountains. Ni-rich sediment, containing i n excess of 150 ppm (Fig 5), i s found adjacent to and as f a r as 10 km east of p e r i d o t i t e bedrock i n the down-ice d i r e c t i o n . Although Cr-rich sediment also appears related to ultramafic bodies, Cr anomalies are more widespread and o v e r l i e approximately twice the area of Ni enrichment. The anomalous dispersion t r a i n also extends an additional 10 km i n the down-3 4 Table II Trace element content of lake sediments (ppm) associated with the p r i n c i p l e geological u n i t s . Bio Tinto survey of the Hechako plateau Element total data Takla volcanics Topley i n t r u s i o n s Hazelton volcanics Jurassic Cretaceous intrusions Endako-Ootsa lake volcanics Sr 760 200-2050 000 100-1350 800 230-2850 770 290-2030 580 170-2010 500 220-1500 Ba 1550 590-0070 1080 310-3780 1890 670-5380 1750 080-6300 1290 090-3020 1150 060-2800 Ct 180 70-190 80 25-200 110 05-280 150 75-300 75 05-100 180 75-010 Co 50 30-80 80 20-300 05 25-70 05 30-60 50 15-100 60 35-95 V 155 65-360 130 55-320 100 60-350 200 80-510 85 50-1-50 130 55-320 Ga 20 10-00 20 8-05 15 7-35 20 9-35 15 10-30 20 9-30 Cu 20. 9-05 01 15-110 18 7-05 20 9-06 05 15-120 19 10-37 Ho 1 <1-3 2 <1-0 1 <1-5 1 <1-0 6 1-20 1 <1-2 Si 22 9-60 13 5-32 9 0-21 18 12-28 20 12-30 28 10-50 Pb <1 <1-2 2 <1-8 <1 <1 1 <1-5 5 1-17 <1 <1-1 Zn 45 25-90 73 18-290 30 16-59 37 21-65 83 25-270 08 28-82 an 250 100-625 235 95-595 260 82-820 265 125-560 700 205-2250 275 90-785 Approximate naaber of sa»ples 670 12 61 16 11 61 R e g i o n a l t h r e s h o l d s (>(mean Cu Mo N i Pb Zn + 2 s t a n d a r d d e v i a t i o n i n t e r v a l s ) ) 95 ppm 9 ppm 151 ppm ppm jjpm 6 237 R* c- Co V and Ra «»re d r a i n e d spectroqraphically and are not corrected for iqnition loss Bean Utai'conUntS are qeo.etric values, ranqe = .«.» .± 1 standard deviation values for Ho and Pb calculated with <1 ppm = 0.5 ppm 35 ice d i r e c t i o n . Despite p e t r o l o g i c a l s i m i l a r i t y , Topley and J u r a s s i c / Cretaceous intrusions are distinguished by d i s t i n c t i v e suites of trace element l e v e l s , lakes associated with the l a t t e r rock type are r e l a t i v e l y r i c h in Cu (lake sediments contain 2.5X more Cu than lakes overlying Topley bedrock) , Mo (6X) , Pb (>5X) , Zn (2.8X), Hi (2.2X) and Mn (2.8X) and are depleted i n V (0.6X). Mn contents are abnormally high, and average values exceed those associated with any other unit. S i m i l a r l y , Cu, Pb and Zn values associated with Jurassic/Cretaceous plutons exceed regional averages by f a c t o r s of 2.3, >5, and 1.8, respectively. However, concentrations are s i m i l a r to those associated with Takla volcanics (Cu-2.0X, Pb->2X, Zn-1.6X regional averages), and the two units cannot be distinguished by Cu, Zn or Pb lake sediment geochemistry. Pb and Zn enhancements associated with Jurassic/Cretaceous plutons coincide with a zone 3 km wide near the base of the Fawnie Bange, downslope of Takla volcanics (Table I I I ) . Topographic position of Pb and Zn-rich lake sediments suggests metal dispersion from the mountains i s a s i g n i f i c a n t factor i n Pb and Zn accumulation. Areas underlain by Topley intrusions are associated with abnormally low Hi contents. Values well below the regional average of 22 ppm, and commonly les s than 8 ppm (x-2<r) , centre on a stock at 420,000 m E and 5,960,000 m N (Fig 5). By contrast. Ho l e v e l s associated with these plutons exceed the regional threshold of 9 ppm (x+2<r) . Enhanced Mo contents are common i n the blithi H i l l s area (Fig 6), but are rare i n association with the previously-mentioned central stock. Mo T a b l e I I I Comparison of t r a c e metal l e v e l s (ppm) a s s o c i a t e d w i t h J u r a s s i c / C r e t a c e o u s i n t r u s i o n s , T a k l a v o l c a n i c s , t h e i r mutual c o n t a c t , and Capoose Lake Element J u r a s s i c / Contact T a k l a Capoose Cr e t a c e o u s -zone v o l c a n i c s Lake i n t r u s i o n s mean s.d. * # mean s.d. # mean s.d. # mean s.d. # ppm ppm ppm ppm ppm ppm PPm ppm Cu 35.0 31.0 19 58.0 49.0 14 28.0 21.0 12 90. 0 34.0 10 Mo 8.4 17. 7 19 U. 1 3. 2 14 2.8 2. 1 12 24. 3 25.4 10 Pb 4.9 2. 0 19 11.0 16. 8 14 7. 8 6.8 12 17. 2 5.5 10 Zn 50.0 25.0 19 240.0 270.0 14 55.0 47.0 12 313.0 153.0 10 1 s t a n d a r d d e v i a t i o n ( a r i t h m e t i c ) # number o f samples 37 values are t y p i c a l l y below average in lakes above the c e n t r a l pluton^ and increase in content i n association with surrounding stocks. Zonation of concentrations i s also a property of Ga, V, Co, Ba, and Sr data. Cu-rich lake sediments are underlain by Jurassic/Cretaceous intrusions near Capoose Lake, and by Topley plutons at Veronica lake and the N i t h i H i l l s (Fig 7). Above average (x+c) Cu values are also found along the Fawnie Range i n association with Takla volcanic rocks. The Green take anomaly i s s t r i k i n g i n t h i s regard. Above average concentrations i n the east are t y p i c a l of 100 to 200 km2 areas underlain by a variety of volcanic, in t r u s i v e and sedimentary rocks concealed beneath thick g l a c i a l overburden. Size of the Cu-rich areas suggest l i t h o l o g i c a l c ontrol. Cu fluctuates apparently randomly over the remainder of the plateau, at l e v e l s below 43 ppm (x+o-j. Pb and Zn l e v e l s (Figs 8 and 9) are above average i n lakes overlying Takla or Hazelton volcanics and areas of extensive overburden cover i n the east. D i s t r i b u t i o n of above average Pb values (>2 ppm) i s more widespread than corresponding Zn contents (>98 ppm). Moreover, Pb values exceeding t h e i r regional threshold of 6 ppm are associated with Takla and Hazelton units along the Fawnie and Nechako Ranges whereas regionally anomalous Zn values of 237 ppm or greater are confined to a northwestward trending belt 10 km wide and 40 km long c l o s e l y associated with Takla volcanic rocks of the Fawnie Bange. Pb and Zn enrichments are also common i n the east i n association with deep g l a c i a l overburden. 3 8 2. Influence of organic matter and Fe on trace metal l e v e l s A f f i n i t y of organic matter for trace elements i s reported by numerous workers (Shimp et a l , 1971; Allan et a l , 1973; Thomas, 1973). On the Nechako plateau, regional trace metal data cannot be correlated with LOI measurements. Lake sediment samples were subdivided into two groups according to LOI ranges of < 2 0 % and >70X (Table IV). Average values within each group indicate certain elements are associated with inorganic sediments, whereas others are associated with f i n e l y - d i v i d e d oozes (Table V ) i Cu, Zn, Pb, Ni, Mn, Sr, Ba; Cr and Ga are r e l a t i v e l y impoverished i n oozes, whereas Mo, Co and V are r e l a t i v e l y enhanced. Correlation of high Pb, Zn, Ni, Mn, Sr, Ba and Ga values with inorganic s i l t s suggests metal l e v e l s are controlled by a provenance factor. S i m i l a r l y , Cr enrichment indicates chromite i s probably an abundant accessory mineral i n nearby bedrock. Maximum l e v e l s of Cu and Mo are found i n samples of intermediate LOI. This probably s i g n i f i e s both organic and inorganic sediment f r a c t i o n s control metal levels. , Correlation analysis indicates a positive c o r r e l a t i o n (r=0.53) for Cu i n samples having an LOI of 0 to 20% (Fig 10). A negative c o r r e l a t i o n (r=-0.47) i s observed amongst data f a l l i n g between 70 to 1008 LOI. Analogous relationships between Zn and organic matter (Garrett and Hornbrook, 1976), and U and organic matter (Cameron and Hornbrook, 1976) are reported for lake sediments from the Canadian Shield. However despite subdivision of Nechako plateau samples into classes, c o r r e l a t i o n of other elements with LOI i s not s i g n i f i c a n t , even over limited ranges Table IV Correlation of trace metal l e v e l s »ith l o s s on i g n i t i o n and lake depth, regional survey ( n = 5 3 7 ) ! toi Cu Ho Ni Pb Zn sr Ba cr Co in V Ga 0. H. 8 <20 0.42 0.20 0.20 0.14 0.22 0.21 -0.15 -0.10 -0.06 0. 17 -0.06 -0.00 -0.05 0.02 N >70 -0.39 0.09 -0.09 0.05 0.03 o.on 0.01 -0.05 0.04 -0.07 0.23 0.03 -0.26 0.21 0-100 0.01 0.07 -0.05 -0. 17 -0.08 -0.07 -0.16 -0.20 -0.01 0. 11 -0.06 0. 24 -0.23 0.13 | L <20 0.53 0.27 0.26 0. 21 0. 26 0.24 -0.23 0. 19 0.01 0.01 -0.03 0.03 -0.15 0.04 L >70 -0.17 -0.01 -0.29 0.03 -0.05 -0.25 o. i i -0.09 -0.09 -0.01 0. 16 -0.05 -0.24 0.14 i- H 0-100 o.os 0.13 -0.01 -0.18 0.08 -0.10 -0.10 -0.22 0.04 0. 19 -0.08 0. 19 -0.20 0.14 Depth B <20 0.11 0.06 -0.03 0.03 0.09 0.34 0.12 0.17 -0.10 -0.02 0.15 -0.11 0.00 0.08 S >70 0.12 0.20 -0.09 0.00 0.20 0.56 0.01 -0.06 -0.05 -0.20 0.46 0.08 0. 18 0.36 N 0-100 0.20 0.08 -0.07 -0.03 0.09 0.39 0.05 0.10 -0.07 0.11 0.22 0.11 0.10 0.29 I <20 0.07 0.15 -0.06 0.05 0.08 0.20 0.00 0.11 -0.13 0.04 0.19 0.12 0.06 0.11 L >70 0.13 ' 0.19 -0.10 0.00 0.21 0.48 -0.03 0.03 0.05 0.07 0.42 0.13 0.16 0.39 L 0-100 0.18 0.19 -0.10 -0.06 0.13 0.38 0.03 0.11 -0.08 0.00 0.25 0.12 0.10 0.28 B - noraal distribution I. - lognoraal distribution 0. M. - organic matter ,.w 4 0 100 50 10 0 50 E 10 5 1 + 70 • • • • • • • • • * t — • • e • A ** e * ••• • * • • • •••>• * • • • • a « ^ * • • • • • • • • • • « . . . # • • • « • > . • * • ••••«••• * * • • • • • * • . « * • • • • •a * • 4) • • • ) • • • • • • *» •** • • » • © • © • • * '9 • 4M • • * • • e O 9 • • • • c *• « • • « • • • • 4 • * n=537 20 40 60 80 Z Loss ON IGNITION 8 12 Z Loss ON IGNITION 20 Y = -0.30X + 3.50,.R2=0.22 n=7 2 L E G E N D • 1 S A M P L E • 2 - 3 S A M P L E S • > 3 S A M P L E S —i— 74 78 82 86 Z Loss OH IGNITION 90 F I G U R E 1 0 : C O R R E L A T I O N O F C U L E V E L S A N D L O I M E A S U R E M E N T S I N L A K E S E D I M E N T S O F T H E N E C H A K O P L A T E A U Table V Trace metal l e v e l s (ppm) i n lake sediment samples, divided on the basis of LOT classes, from the Nechako plateau HTZ aAS and DBC emission spectrometries data Normal D i s t r i b u t i o n Lognornal D i s t r i b u t i o n ' LOI LOI LOI LOI LOI LOI <20% >70X 0-100% <20X >70S 0-100X mean s.d.* mean s.d. mean s. d. mean s.d. mean s.d. mean s.d. 0M% 10.i» 6.7 78.5 6. 1 Oft.3 21.9 cu 20.1 20. 8 18.8 1ft.3 25.8 20.7 13.8 0.ft3 13.5 0.39 19.0 .37 So 1.8 6.5 2.1 ft.9 . 2.5 11.5 1.32 0.31 1.51 0.35 1.51 .35 Ni «3.0 86.2 28.9 32.5 36.0 59.3 21.ft 0.ft9 17.ft 0.ft7 20.ft 0. ft7 Pb 2.7 7. ft 0.ft2 1.16 1.2 3.8 1.70 O.ftO 2.63 0.17 1.35 0.29 Zn 57.0 61.8 «ft. 2 27.5 5ft.9 61.6 ft1.7 0.37 33. 1 0.01 39. 8 0.38 Hn 510. 975. 298. 3 25. 005. 870. 302. 0.ft6 182. 0.55 229. 0.ft8 Sr 1750. 970. 1230. 1100. 1100. 930. 1318 0.ft8 72ft. 0.62 589. 0.68 Ba 3U00. 2200. 2050. 2150. 2300. 2050. 2630 0.36 1350 O.ftO 1550 0.ft2 Cr 3 80. 580. 3ft7. 385. 305. ft25. 21ft. 0.ft9 219. 0.ft3 186. 0.ft5 Co oo. 0 33.8 65.ft 2«.5 57.9 51.3 33.1 0.36 53.7 0.35 ft6.8 0.31 In 52. 2 ftft.2 ft7. 3 27. 1 ft5. 1 ft1.9 06.8, 0. 16 01.7 0.21 38.9 0.20 V 18ft. 158. 329. 266. 230. 210. . 141. 0.29 22ft. 0.ft2 158. 0.37 Ga 27.9 10.6 19.0 9.2 22.6 10.6 25.6 0.28 15.9 0.31 19.0 0.30 an* 1550. 1200. 22ft0. 2100. 1600. 1ft70. 1380 0. 18 17ft0 0.28 1320 0.25 D 3 11.0 16.2 10.8 9.5 13.3 15.8 n= 135 72 537 135 72 537 DBC AAS data on 100 sample subset Cu 22.2 19.1 17.3 0.32 Zn 53.5 05.1 03.0 0.28 Fe% 1.65 1.08 Hn ftftO. 1300. 261. 0.35 Pb 1.2 3.2 1.37 0.30 HO 10.0 9.3 6,27 0.51 n= 100 100 * emission s p e c t r o m e t r i c data f o r Mn * standard d e v i a t i o n f o r lognormal d i s t r i b u t i o n given i n l o g a r i t h m i c terms * standard d e v i a t i o n ' depth 42 of LCI values. Fe and Mn oxides are also capable of scavenging trace elements (Mackereth, 1966). However an estimate of the importance of Fe oxide control on trace element v a r i a b i l i t y i s preliminary because only 15% of the regional samples were analyzed for Fe. Although regression analysis indicates a strong a f f i n i t y of Fe for Mn (r=0.60) and Mn f o r lake depth, scavenging of Cu, Zn, Mo, Co, Ni or other trace elements by Fe oxides i s not suggested. 3. Helevence to mineral exploration Regional d i s t r i b u t i o n s of Cu, Mo, Pb and Zn, and p a r t i c u l a r l y values exceeding regional thresholds (Table I I ) , are of i n t e r e s t i n mineral exploration. Several mineral prospects were recognized on the Nechako plateau (Figs 2 to 9) prior to conducting the lake sediment survey. They include low grade, fr a c t u r e - c o n t r o l l e d chalcopyrite and molybdenite occurrences north; east and south of Capoose Lake; galena i n veinlets south of Green Lake; sphalerite-molybdenite-chalcopyrite showings near the contact of a Jurassic/Cretaceous grancdiorite and a r g i l l i t e of the Hazelton volcanics at Fish and Portnoy Lakes; and guartz-molybdenite veinlets i n Topley intrusions of the N i t h i h i l l s . Lakes are enriched i n one or more elements i n proximity to mineralized bedrock (Table 71). Average metal content of lake sediment i n anomalous areas may be as high as 4.5X the regional threshold (defined as contrast r a t i o i n Table VI). Several anomalies unrelated tc known mineral showings were 4 3 T a b l e VI Geology and geochemistry of mineralized prospects on the Nechako plateau Prospect No. of No. of Lake Element Average Standard Contrast lakes anomalous class' value deviation ratio' samples (ppm) (ppm) Properties recognized prior to the lake sediment survey 1. Capoose Lake — chalcopyrite and molybdenite with quartz veinlets and along fracture zones within the Capoose Lake granodiorite 2. Green Lake — contact zone between altered Takla volcanics and Capoose Lake granodiorite; prominent gossan NW and SW of lake 3. Fish and Portnoy Lakes — chalcopyrite-molybdenite-sphalerite and pyrite-pyrrhotite occur as disseminated grains in hornfels and quartz veinlets cutting Hazelton metasediments and volcanics adjacent to a Jurassic/ Cretaceous stock 4. Nithi Hills — molybdenite-chalcopyrite mineralization in thin quartz stringers within Topley quartz-monzonite, granodiorite and diorite 1 7 1 Cu 110. H.5 1.16 1 10 1 Mo 24.3 25.4 2.87 1 10 1 Pb 17.2 5.5 2.87 1 10 1 Zn 313. 153.0 1.32 1 1 1 Mn 8200. 2.83 1 2 1 Co* 275. 75.0 1.73 ! 3 x Cu 137. 46.0 1.44 1 3 1 Pb 10.7 0.6 1.78 1 3 1 Zn 617. 362. 2.60 1 3 1 Co* 600. 264. 3.77 ! 1 2 Cu 53.0 0.56 2 2 Mo 19.5 7.8 2.17 4 4 2 Pb 13.0 6.0 2.17 2 2 2 Zn 235.0 149.7 0.99 9 9 2 Ba* 7200. 5070. 1.46 2 2 2 Ag* 2.5 0.7 2.50 3 3 2 Cu 88.0 22.0 0.93 11 11 2 Mo 40.6 69.0 4.51 16 16 2 Ag* 1.6 0.7 1.56 9 9 2 Sr* 4100. 1600. 1.43 14 14 2 Ba* 6850. 2450. 1.38 Properties examined following the lake sediment survey 5. Canoe Lake — intercalated flows, pyroclastics and sediments of the Hazelton group volcanics 6. Veronica Lake — Topley diorite, minor granodiorite and granite 7. Hogsback Lake — extensive glacial till; probable basement of Topley bedrock 8. Bobtail and Sinkut Mountains — widely spaced chrysotile veinlets and nickel silicates in serpentinized peridotite in contact with limestone of the Cache Creek group 1 8 1 1 3 1 2 (area 1) 4 (area 2) 5 (area 2) 1 (area 2) 3 (area 2) 7 (area 1) 1 (area 2) 8 (area 3) 2(area 4) 3 (area 5) 1 (area 6) 1 1, 2 Mo 12. 1.33 8 1, 2 Ba* 5000. 1.01 1 1, 2 Mn* 10000. 3.46 1 1.2 V* 700. 1.10 3 2 Cu 81.7 35.0 0.86 1 2 Mo 28. 3.11 3 2 Mo 13.8 7.6 1.53 4 2 Cu 64. 13.9 0.67 5 2 Mo 16. 9.8 1.84 1 2 Zn 210. 0.89 3 2 Ni 163. 68.0 1.08 7 2 Ni 136. 31.0 0.90 1 2 Ni 105. 0.70 9 1, 2 Ni 380. 323. 2.52 3 2 Ni 199. 73.0 1.32 5 2 Ni 186. 42.0 1.23 6 1 Ni 293. 162. 1.94 *Emission spectrometry data on ignited samples, otherwise A AS results on hydrochloric leaches of nitric and perchloric acid digestion residues. 1 Lake class: 1 = oligotrophia, 2 = dystrophic or eutrophic. 1 Contrast ratio: average anomaly value/regional threshold (regional thresholds are: Ni 150 ppm, Cu 95 ppm, Mo 9 ppm, Pb 6 ppm, Zn 231: ppm, based on x + 2a). 44 subsequently found to be associated with showings, favourable geology, or s o i l or stream sediment geochemical anomalies. These include the Canoe - Baxter Lake Mo anomaly associated with argillaceous sedimentary rocks of the Hazelton Group; the Veronica Lake Cu - Mo enhancement r e f l e c t i n g Topley bedrock; the Hogsback Lake Cu—Mo - Zn - Ni enrichment, probably re l a t e d to Topley and ultramafic intrusions; and the Bobtail - Sinkut Mountain Ni anomalies associated with serpentinized p e r i d o t i t e s (Table VI) . The Canoe - Baxter Lake anomaly may also r e f l e c t g l a c i a l dispersion of metal-rich material from the Fish -Portnoy Lake occurrence, 8 km up-ice (Mehrtens et a l , 1973). Each mineral prospect i s represented by 1 or more anomalous lake sediments. In view of the regional significance of the Capoose Lake prospect, which i s described i n further d e t a i l i n Chapter 6, a t o t a l of 10 samples was collected to investigate trace metal v a r i a b i l i t y . Levels fluctuated up to 12X the lowest value (Table VII) as a res u l t of textural differences between d e l t a i c sands of Capoose Creek and more finely-divided oozes, both c o l l e c t e d near the middle of the lake. , Other large lakes sampled more than once also display variable metal contents. E. Discussion Application of lake sediment sampling to mineral exploration i s based on the premise that the lake acts as a trap fo r both mechanically transported and dissolved metals. Input of anomalous metal concentrations may be due to transport of metal-rich stream sediments and waters, dissolved metals i n groundwaters, erosion of lake banks or f a l l o u t of wind-borne Table V I I Comparison of t r a c e metal c o n t e n t (ppm) i n d e l t a i c and c e n t r a l b a s i n sediment of Capoose l a k e , based on samples c o l l e c t e d on the r e c o n n a i s s a n c e s u r v e y Deltaic sediments B a s i n a l Sediments Element mean s . d . 1 number of mean s.d. number of ppm ppm samples ppm ppm samples Cu 43.0 2.5 110. 11.5 Mo 6.3 1.5 32. 27.0 Pb 13.0 1.7 19. 5.6 Zn 119. 5.0 396. 92.0 i s t a n d a r d d e v i a t i o n ( a r i t h m e t i c ) 46 material. Once i n the lake, dissolved elements may become fixed i n lake sediments by a variety of limnological processes. Planktonic assimilation and absorption or cop r e c i p i t a t i o n by organic matter and hydrous iron and manganese oxides are probably p a r t i c u l a r l y important and may be of a seasonal nature. Bedrock geology of the Nechako plateau i s poorly understood, even i n the mountains. Despite t h i s uncertainty, trace element association with l i t h c l o g y i s easily recognized because many of the geological units are characterized by enrichment i n one or more metals. The examples of enhanced Ni and Cr contents near Mesozoic p e r i d o t i t e s , and Cu and Mo enrichment and Ni depletion associated with Jurassic/Cretaceous and/or Topley plutons are s t r i k i n g i l l u s t r a t i o n s . S i m i l a r l y , Pb and Zn enrichment appears to r e f l e c t Takla and Hazelton volcanic rocks. Relatively strong c o r r e l a t i o n of geology and lake metal l e v e l s i s somewhat surprising in view of the extensive Pleistocene g l a c i a t i o n of the plateau; However g l a c i a l deposits are r e l a t i v e l y minor i n the mountains, and correspondence of trace element distrubtions and geology i s not unexpected i n these regions. In the eastern part of the study area where g l a c i a l dispersion was extensive and s u r f i c i a l deposits are thick, strength of the Cr and Ni anomalies, p a r t i c u l a r l y down-i c e , s i g n i f i e s unusually large concentrations of these elements i n bedrock are not e a s i l y masked by g l a c i a l action. Levels of trace elements associated with other geological units are not as c h a r a c t e r i s t i c . Consequently dispersion t r a i n s are not as prominent as i n the case of Ni and Cr. 47 Topographic r e l i e f plays a major role i n c o n t r o l l i n g mechanical erosion. Stream networks are well-established i n the mountains, and suspended metal-rich fines or bed loads are important in metal transport to a lake. Metals dissolved i n stream and ground water also may be s i g n i f i c a n t , p a r t i c u l a r l y i f the water solution i s strongly a c i d i c , anomalies r e f l e c t i n g the influence of topography are i l l u s t r a t e d by the Pb and Zn accumulation i n Capoose Lake, and by Mo enrichment i n lakes of the N i t h i H i l l s . Pb and Zn sulphides have not been recognized as accesory minerals of the granodiorite surrounding Capoose Lake. However-galena has been observed south of Green Lake (Nahring, 1971). In view of the fact Capoose Lake occupies a position central to a stream network draining the Pb and Zn-rich areas near Green Lake, anomalous concentrations of these metals probably are derived from the mountains. S i m i l a r l y , enhanced l e v e l s of Mo i n lakes along the Nlthi Biver valley probably are derived from surrounding granite h i l l s by a combination of mechanical and hydromorphic processes (unpublished report, Subramanian, 1972) Despite attempts to characterize physical and chemical properties of a lake, v a r i a b i l i t y associated with sediment texture and consistence may greatly a f f e c t trace metal l e v e l s . Influence of textural v a r i a b i l i t y can be visualized by comparing the trace metal content of sands and f i n e l y - d i v i d e d oozes. Consider the e f f e c t scavenging by a sediment f r a c t i o n , or metal p r e c i p i t a t i o n from lake water w i l l have on lake sediment trace metal l e v e l s (Timperley and ftllan, 1974). Finely-divided oozes, because of th e i r greater volume of material and surface area 48 associated with a unit of dry weight sediment, are more l i k e l y to scavenge trace elements. In addition, the larger volume w i l l hold more of an evenly deposited p r e c i p i t a t e than the l o s e r volume sands. Consequently potential f o r spurious r e s u l t s related to sediment density i s great, and may be seasonally-controlled (Gorham et a l , 1974). V a r i a b i l i t y i s also increased by employing a sampling device, such as a mud snapper, which penetrates s u r f i c i a l sediment to varying degrees, up to depths of 10 cm, depending on sediment consistency. a number of other parameters can influence trace metal le v e l s as much as sediment texture. Composition of organic matter* abundance of Fe and an oxides, abundance of calcium carbonate p r e c i p i t a t e s , lake environment, and other f a c t o r s may control extent of metal accumulation, i f any. Although these factors are ignored i n the present study, and the Nechako plateau lake sediment survey successfully outlined regional l i t h o l o g i c a l units and a l l previously recognized mineral showings, they nevertheless may affect the degree of success (or f a i l u r e ) of a survey;, Consequently, influence of sediment composition and texture on trace metal l e v e l s i s assessed in Chapter 5. Further, v a r i a b i l i t y of trace element concentrations within a single lake i s evaluated i n Chapter 6 for Capoose, Fish, and Portnoy Lakes. £. Application to exploration Interpretation of genesis of lake sediment anomalies i s subject to a great deal of uncertainty i f only 1 sample i s c o l l e c t e d per lake. In areas where mineralized bedrock i n a 49 drainage basin i s recognized, a connection linking lake anomalies to known mineral occurrences may appear reasonable. Nevertheless other f a c t o r s may control metal accumulation. In regions where mineral showings are unknown and lake sediment anomalies are prominent, lake sediment data only i n d i c a t e the probable regional significance of the drainage basin. However source of the metal causing the lake sediment anomaly cannot be ascertained without additional sampling. Capoose Lake i l l u s t r a t e s the importance of choice of sample location i n d e f i n i t i o n of the anomalous character of a lake. Samples near the middle of the lake contain only 40 ppm Cu and 5 ppm Ho. However sediments from the middle of each basin contain up to 125 ppm Cu and 73 ppm Mo. Because mineral showings i n the Capoose Lake drainage basin are prominent, the anomalous nature of the area would probably be detected by reconnaissance geochemical or geological surveys. However in watersheds where showings are unknown or poorly exposed, an anomalous lake could be missed by unfortunate choice of sample location. This f a i l u r e would not be evident u n t i l a second lake survey or other exploration method defined a geochemical anomaly or mineralized bedrock. In undertaking a lake sediment survey, several physical and chemical parameters must be recorded at the time of sample c o l l e c t i o n to supplement chemical analysis. Information i s tabulated according to a •reconnaissance (recce) data* format coded for computer applications (Fig 11). although geological control i s generally poor, success of a lake sediment program can be maximized by proper choice of sample location within the F I G U R E 1 1 : ' R E C C E D A T A ' F O R M A T F O R R E C O R D I N G R E C O N N A I S S A N C E L A K E S E D I M E N T I N F O R M A T I O N / F O R F I E L D A P P L I C A T I O N S C O L . 4 0 D E S C R I P T I O N TOPOGRAPHY-SETTING OF LAKE ON LANDSCAPE 1. Cirque basin 2. Gentle slope 3.Steep slope 4. Footslope 5. Valley floor >20u 6. 7. Level 8. Rolling 9. Major bog C O L , D E S C R I P T I O N 4 7 , 48 pH 49-51 MAXIMUM LAKE LENGTH IN METERS T 10 52-54 MAXIMUM LAKE WIDTH IN METERS -r 10 C O 7* 41 DRAINAGE BASIN ENVIRONMENT 1. Tundra-arctic 2. Tundra-alplne 3. Grass land, pasture,meadows 4. Bog, swamp 5. Forest-con Iferous 6. Forest-deciduous 7. Forest-mixed 8. Cultivated land 57 9.Semi arid to desert 55,56 LAKE DEPTH AT POINT OF SAMPLING-METERS 72 73 4 2 LAKE ELEVATION-FEET 1. 0- 2000 2.2001- 4000 3.4001- 6000 4.6001- 8 0 0 0 5.8001-10P00 6.10,001-12,000 7.12,001-14,000 8.14,001-16,000 9. >16,000 43 WATERSHED AR|A 1. Low 0-3 km _ 2. Moderate 4-20 km , 3. Relatively large 21-50 km 4. Very large >50 km i 44 OVERBURDEN TRANSPORT 1.Local 2. Extensive 45 PREDOMINANT GLACIAL OVERBURDEN . l . T ! l l 2.0utwash sard 3. Gravel 4. Alluvium 5. Peat 6. ColluvIum 7. Lacustrine clay 8. Talus 9. Residual 46 FLUSHING RATE 1. Low 3.High 2. Moderate ISLANDS 1. None 3.Moderate density 2. Low density 4.High density 58-60 LOCAL BEDROCK COMPOSITION 78-80 - estimate 61 LAKESHORE CHARACTER B.boggy S. sandy-M.mixed boggy and sandy R.rocky 62 LAKESHORE COMPLEXITY 1.Straight 3-lrregular 2.Undulating 4.Contorted 63-68 COLOUR Munsell notation or rock form mnemonics 69 70 NUMBER OF MAJOR INFLOW STREAMS l.None 4. 3-5 2.1 5- 5-10 3.2-3 6. >10 . 74 75 76 77 D E S C R I P T I O N SAMPLE HOMOGENEITY 1. Homogeneous 2. Layered 3. TurbtdIte CONS ITENCY-SEDIMENT WATER CONTENT 1.Soupy 3.Other 2.Firm TEXTURE 1. Nearshore sands or gravels 2. Deltaic sands or gravels 3. Woody 4.Sapropel-we! 1 decomposed vegetation 5. AIgal mat 6. Benthlc vegetation 7. Minor sand content 8.Inorganic f inely textured 9.Pre-lake deposits PRECIPITATES 1. Fe sesquioxldes 2. Mn sesquioxldes 3. Calcium carbonate FEATURE 1. Fe concretions 3.Fe+Mn concretions 2. Mn concretions 4.Shell fragments SEDIMENT ODOUR 1. Hydrogen sulphide 3.None 2. Fishy LAKE WATER COLOUR I.Clear 3.Strongly yellow 2.Sl ightly yellow PROXIMITY OF SAMPLE SITE TO MAJOR INFLOW STREAM 1. 0- 50m 4. 251-500m 2. 51-100m 5. >500m 3.10I-250m 51 lake and complete record of measureable lake parameters. V a r i a b i l i t y a t t r i b u t a b l e to depth of sampling may be circumvented by replacing the mud snapper with an Ekmaa dredge or Phleger corer. On the Nechako plateau, v a r i a b i l i t y r esulting from geological, limnological and other factors, does not mask abnormally high metal values related to mineral occurrences. Anomaly contrast (contrast ratio) i s usually 1.5X to 2X regional threshold. V a r i a b i l i t y within an anomalous region i s r e f l e c t e d by contrast r a t i o s as high as 45X the regional threshold, i n i n d i v i d u a l lakes. Differences i n behaviour of elements are also apparent (Table VI). Sediments from Capoose lake are more strongly anomalous for Ho (2.7X) than for Cu (1.2X). These differences presumably r e f l e c t differences in mineral concentrations and/or dispersion processes into and within the lake; In t h i s respect, i t should be noted that though mechanical transport of anomalous stream sediments may be s i g n i f i c a n t into large o l i g o t r o p h i a lakes, metal-rich groundwaters are probably the only important source of anomalous metal values i n eutrophic lakes. Success i n r e l a t i n g trace element content of lake sediments to bedrock geology and aineral occurrences have been reported i n studies by Allan (1971), Hoffman and Fletcher (1972) and Davenport et a l (1975). In contrast, on the southern Canadian Shield, Coker and Nichcl (1975) found i t d i f f i c u l t or impossible to distinguish lakes near mineral showings from those i n barren t e r r a i n on the basis of single element analyses. This problem was related to trace element scavenging by Fe and Hn oxides, and 52 was overcome using metal r a t i o s . Despite obvious physiographic, c l i m a t i c , pedologic and other differences between the regions studied by various workers, i t remains uncertain what factors are primarily responsible f o r r e l a t i v e differences i n success of lake sediment surveys. The high organic productivity and muskeg environment of the southern Shield i s probably e f f e c t i v e i n mobilizing trace elements from oxidizing sulphide deposits; However i n areas of subdued r e l i e f , groundwater flow i s l i k e l y to be low compared to i t s more vigorous-movement i n h i l l y cr mountainous t e r r a i n . Consequently, other factors being egual, rates of hydromorphic metal accumulation i n lake sediments are l i k e l y to be lower i n the Shield than i n the C o r d i l l e r a . F. Summary • Despite problems associated with transport of metals into lakes and t h e i r subseguent r e d i s t r i b u t i o n , the r e l a t i o n s h i p between lake sediment geochemistry, geology, and mineral prospects appears to be d i r e c t . Relative s i m p l i c i t y of lake sediment geochemistry i n the C o r d i l l e r a compared to the Shield probably r e f l e c t s o v e r a l l physiographic conditions of more rugged topography favouring rapid migration of trace metals from bedrock to lake sediment by mechanical or chemical dispersion. Rapid accumulation of metals, combined with the l o c a l nature of the g l a c i a l deposits allows f o r a r e l a t i v e l y d i r e c t i nterpretation of anomalous conditions. 53 CHAPTER 4 ANALYTICAL TECHNIQUES I SAMPLE COLLECTION AND PBEPAEATION A. Introduction The reconnaissance survey of Eio Tinto was followed by studies of Cu, Mo, Pb and Zn anomalies at Capoose, Green, Fish and Portnoy Lakes conducted between June and August, 1971. In addition to detailed sediment and water sampling of lakes, s o i l s , bogs, seepages, and streams near previously defined s o i l and bedrock anomalies and surrounding lakes were also sampled. Table VIII summarizes types and numbers of samples c o l l e c t e d on reconnaissance and follow-up surveys. B. Stream, spring and lake sediments Stream sediments were taken at approximately 120 m i n t e r v a l s along creeks draining previously defined (by Bio Tinto) s o i l anomalies or mineral showings, and at inflow and outflow points around the lake margins. Wherever possible an e f f o r t was made to c o l l e c t f i n e l y textured s i l t s . However in smaller creeks i t was often d i f f i c u l t to avoid organic-!-rich muds. Information recorded in-the f i e l d included sample lo c a t i o n , sediment texture, odour, vegetation, and nature of the stream hed.- , Lake sediment samples were collected from Capoose, Fi s h , and Portnoy Lakes (Table IX). Sample location was controlled by stretching nylon cord l i n e s across the lakes at 200 to 300 m i n t e r v a l s . Samples were taken at 7 m, 15 m, and 30 m distances 54 T a b l e V I I I T y p e s a n d n u m b e r s o f g e o c h e m i c a l s a m p l e s c o l l e c t e d d u r i n g 1 9 7 0 -1 9 7 1 P r o p e r t y - L a k e L a k e L a k e S t r e a m S t r e a m S o i l w a t e r b o t t o m c o r e s w a t e r s e d i m e n t s e d i m e n t H e c o n n a i s a n c e 6 5 6 C a p o o s e a n d G r e e n L a k e s 1 9 7 1 2 7 17 1 7 5 1 2 6 4 9 7 F i s h a n d P o r t n o y L a k e s 3 9 34 12 2 3 ' 2 2 1 6 8 T a b l e I X S u m m a r y o f d e t a i l e d l a k e s e d i m e n t s a m p l i n q o f t h r e e l a k e s o n t h e N e c h a k o p l a t e a u p r o s p e c t N e a r s h o r e B a s i n a l C o r e l a k e s e d i m e n t s s e d i m e n t s s a m p l e s C a p o o s e 24 1 0 3 17 F i s h 9 13 6 P o r t n o y . 4 8 6 55 from each shore, and then at 61 m i n t e r v a l s . Lake water temperature, depth, and pH were recorded, together with sediment colour, odour, and texture. Presence of s t r a t i f i c a t i o n , calcium carbonate pre c i p i t a t e s , wood fragments, and shells were also noted. Approximately 0.5 kg sediment samples were saved i n prenumbered Kraft paper envelopes (8X24 cm) and a i r dried at ambient temperatures for 1 to 4 weeks. Stream and seepage sediments were disaggregated and sieved to -80 mesh. Lake sediments required pulverizing with a mortar and pe s t l e , or jaw crushing and grinding i n a shatter box. Lake sediment cores were co l l e c t e d along several of the traverse l i n e s using a Phleger corer l i n e d with p l a s t i c tubing, l a t e r above the sediment was decanted, and the tube was sealed with wax and e l e c t r i c a l tape. Host of the cores dried at ambient temperatures over a period of 2 years. Hoist cores, however, were dried at 110°C for 24 hours before ana l y s i s . Half of each core was retained in monclith form (Day, 1968), and the remainder was divided into recognizable layers and disaggregated for analysis. C. Stream, spring and lake water Stream and spring water samples complement sediment samples around each lake and at 120 m i n t e r v a l s along streams draining previously reported-base metal anomalies. i i t h i n lakes, water samples were routinely collected 0.5 m above the lake f l o o r i n a 1.5 l i t r e Van Dorn (Kahl S c i e n t i f i c Company) bo t t l e . Hater temperature was measured i n s i t u from the surface to the lake f l o o r using a Kahl S c i e n t i f i c Company thermometer. r Temperature 56 diminishes with increased lake depth i n a fashion reported by Coker and Nichol ( 1 9 7 5 ) T h e r e s u l t i n g temperature p r o f i l e formed the basis for more detailed water sampling at 0.7 m, 3 m, above and below the thermocline, and then at 6 m i n t e r v a l s u n t i l the lake bottom was reached. ilater samples were stored i n 500 ml acid washed (50% n i t r i c acid) Nalgene bottles and a c i d i f i e d with 1 ml of concentrated n i t r i c a cid at the end of the day. Determinations of pH (Orion model 404 pH meter or BDH universal i n d i c a t o r ) ; bicarbonate (Applied Geochemical Research Group Technical Communication (AGRGTC) 26); sulphate (AGRGTC 27) ; and chloride (AGRGTC 29) were completed within several days of sample c o l l e c t i o n on un a c i d i f i e d aliguots. l a t e r colour was also recorded with reference to a Hach Chemical Company colour disc. Samples were then shipped to the University of B r i t i s h Columbia (OBC) for trace metal analysis. Duplicate water samples were c o l l e c t e d at selected s i t e s and f i l t e r e d through Hhatman #41 paper prior to a c i d i f i c a t i o n with 1 ml of concentrated n i t r i c acid. Comparison of trace metal values i n f i l t e r e d and u n f i l t e r e d samples shows that, f o r lake waters, the l a t t e r contains up to 3X greater trace element concentrations (Table X). In contrast, trace metal content of stream water i s approximately the same in both sets of aliguots. D. S o i l s Samples from the top of the *B* horizon were c o l l e c t e d by digging p i t s every 60 m along predetermined traverse l i n e s selected on the basis of prior Rio Tinto d e f i n i t i o n of base Table X Comparison of trace metal data (ppb) in f i l t e r e d and un f i l t e r e d water samples Piver U n f i l t e r e d Water F i l t e r e d Ratio F i l t e r e d / n n f i l t e r e d Lake Unf i l t e r e d Water F i l t e r e d Ratio F i l t e r e d / U n f i l t e r e d Threshold 10 12 26 5 Cu Mean 2 2 1 3 1 0.33 Range 1-5 1-5 1-8 1-3 Threshold 19 21 185 40 Zn Mean 5 7 • 1.4 . 27 9 0.33 Range 3-10 4 -12 10-71 4-19 Threshold 1000 780 6700 920 Pe Mean 1°0 1214 0.65 245 142 0.58 Range 77-450 50-310 47-1300 56-360 Threshold U7 23 1200 260 Hn Mean 6 a 0.67 19 18 0.95 Range 2-17 ' 2-10 2-150 5-68 Threshold 7 U 5 nd Ho Mean 2 1 0.50 1 nd Range 1-3 1-2 1-2 nd Number of Samples 10 10 44 44 nd - n o t d e t e c t e d mean - c a l c u l a t e d f o r a l o g n o r m a l d i s t r i b u t i o n range - l o g n o r m a l mean + 1 s t a n d a r d d e v i a t i o n t h r e s h o l d - >(mean + 2 s t a n d a r d d e v i a t i o n i n t e r v a l s ) 58 metal overburden anomalies. In places samples were taken from other horizons or parent material within p r o f i l e p i t s dug 0.3 to 1.3 m deep. P r o f i l e stations were chosen with reference to l o c a l topography and position of previously outlined trace element anomalies. Distance between p i t s varied between 30 and 300 m. Samples weighing approximately 0.5 kg were placed i n prenumbered K r a f t p a p e r envelopes (8X24 cm) and a i r dried at ambient temperatures. A n a l y t i c a l f i e l d procedures follow those of Lavkulich (1969). F i e l d notes include: 1. Sample location (local grid coordinates) 2. S o i l consistence - the force necessary to impress a knife into the v i r g i n s o i l horizon was correlated with hand analysis, 3. Percentage of a s o i l sample coarser than 2 mm i n diameter: pa r t i c u l a r attention i s given to fragment shape; degree of angularity; weathered character; extent of Fe oxide or malachite stai n i n g ; evidence of mineral concentrations; and percentage, variety and nature of rock types comprising the coarse f r a c t i o n , 4. Depth of plant roots and nature of overlying vegetation, 5. Direction and slope of ground surface, 6. Topography i n immediate v i c i n i t y of sample lo c a t i o n . S o i l sample pretreatment i s s i m i l a r to that described for stream sediments (page 53). II SAMPLE EXTRACTION PEOCEDURES A. S o i l , spring and sediment samples 1. N i t r i c and perchloric acid digestion 59 A n i t r i c / p e r c h l o r i c acid digestion i s used to determine • t o t a l * metal contents (Fletcher, 1971). In t h i s procedure, 0.5 g s p l i t of ground sample or -80 mesh sample f r a c t i o n i s placed i n an acid washed 50 ml beaker containing several m i l l i l i t e r s of d i s t i l l e d water (to prevent dusting, or frothing of carbonate-r i c h samples), 5 ml of a 4:1 n i t r i c / p e r c h l o r i c acid mixture i s added, and the contents of the beaker are evaporated to dryness (4 hours). The residue i s then extracted with 3 ml of concentrated hydrochloric acid and several m i l l i l i t e r s of d i s t i l l e d water, the solution transferred to a graduated test tube (22 X 175 mm) and diluted to 25 ml with d i s t i l l e d water. 2. P a r t i a l extractions Four p a r t i a l extraction reagents were employed to dissolve weakly-bound trace elements from selected lake sediment samples. In a l l cases, 1.0 g of ground or -80 mesh sample i s added to a test tube (22 X 175 mm) and 10 ml of one of the four reagents i s added. 1. 0.5 M hydrochloric acid, 2. 1.0 N ammonium acetate, pH=7.0, 77.08 g ammonium acetate dissolved i n 1 1 of water, 3. Acid ammonium oxalate (Tamm*s reagent), pfl=3.5, 24.9 g ammonium oxalate monohydrate and 12.6 g oxalic acid dihydrate dissolved i n 1 1 of water, 4. 0.05 a EDTA, pH=4.7, 18.61 g (dihydrate) disodium s a l t of EDTA dissolved i n 1 1 of water. After addition of the extraction reagent, test tubes are stoppered and shaken mechanically for 10 hours. The suspension 60 i s allowed to s e t t l e for a day, after which the supernatent solution i s decanted and analyzed by atomic absorption or colorimetry. 3. Sequential p a r t i a l extractions The sequential p a r t i a l extraction procedure i s outlined i n Pig 12. Discussion regarding the purpose of each step and assumptions of the procedure w i l l be found in Chapter 5. A 1.0 g sample i s placed in a t e s t tube (20 X 155 am) and 10 ml of reagent grade sodium hypochlorite solution (4 to 6 percent active c h l o r i n e ) , freshly adjusted to pH 9.5 with 1.5 M hydrochloric acid, i s added to oxidize most of the sample organic matter (Lavkulich and Siens, 1970). Test tube contents are agitated intermittently for 10 hours and then placed i n a steam bath at 90°C for 3 hours. The sample i s cooled to room temperature and centrifuged, and the supernatent l i g u i d i s decanted into a clean test tube (22 X 175 mm)., The a g i t a t i o n , heating and cooling procedure i s repeated with another 5 ml of reagent and the*decanted l i q u i d combined with that from the f i r s t extraction. Additional sodium hypochlorite may be required i f the sediment continues to appear organic-rich and gives brown, strongly coloured extracts. F i n a l l y , the residue i s washed with up to 3 successive 5 ml portions of d i s t i l l e d water to y i e l d a f i n a l volume of 30 ml. The procedure continues with the addition of 10 ml of d i s t i l l e d water* adjusted to pH 2.5 by 1.5 B hydrochloric acid, to the hypochlorite residue; This a c i d i f i e d d i s t i l l e d water dissolves base metal precipitates formed as a consequence of the 1. SAMPLE SIEVED TO -80 MESH AFTER DISAGGREGATION 2. APPLICATION OF SODIUM HYPOCHLORITE AT PH 9.5 3. APPLICATION OF DISTILLED WATER, ADJUSTMENT — OF PH TO 3.0 ±0.3 WITH HYDROCHLORIC ACID 4. APPLICATION OF HYDROXYLAMINE HYDROCHLORIDE, PH 2.5 FOR 30 MINUTES 5. APPLICATION OF ACID AMMONIUM OXALATE (TAMM'S REAGENT) ADJUSTED TO PH 3.5 6. APPLICATION OF CITRATE-DITHIONITE-BICARBONATE — AT PH 7.0 7. APPLICATION OF HYDROGEN PEROXIDE AT PH 3.0 8. APPLICATION OF NITRIC/PERCHLORIC ACIDS TO RESIDUE 9. ADDITIONAL WET SIEVING AT 270 MESH FIGURE 1 2 : OUTLINE OF THE SEQUENTIAL ATTACK PROCEDURE DESTRUCTION OF ORGANIC MATTER DESTRUCTION OF SULPHIDE MINERALS SOLUTION OF ADSORBED TRACE METALS RESOLUTION OF METAL-HYDROXIDE PRECIPITATES SOLUTION OF CARBONATE MINERALS SOLUTION OF MOST SOLUBLE MANGANESE AND IRON COMPOUNDS AND SCAVENGED TRACE METALS SOLUTION OF MORE RESISTANT AMORPHOUS IRON AND MANGANESE OXIDES AND SCAVENGED TRACE METALS SOLUTION OF CRYSTALLINE IRON , OXIDES AND CONTAINED TRACE METALS RESOLUTION OF TRACE METAL SULPHIDE PRECIPITATES FORMED AFTER DITHIONITE APPLICATION SOLUTION OF TRACE ELEMENTS ASSOCIATED WITH RESIDUE SILICATES ESTIMATE OF THE SAND CONTENT OF THE SAMPLE 62 alkaline conditions of the hypochlorite extraction. Contents of the test tube are shaken and pH of the res u l t i n g suspension measured with a pH meter employing a combination glass-calomel electrode pair. Suspension pH i s adjusted to 3.0 ±0.3 by addition of 1w5 M hydrochloric acid which i s delivered dropwise from a burette. Volume of acid and f i n a l pH are recorded and the supernatent solution reserved. Next, 10 ml of 0.1M hydroxylamine hydrochloride (6.949 g/1)-, a c i d i f i e d to pH 2.5 with 6 M hydrochloric acid, i s added to leach amorphous fln oxides and the contents are agitated intermittently for 30 minutes and centrifuged. The supernatent l i q u i d i s saved and residues are washed with 10 ml of d i s t i l l e d water. Treatment i s continued to dissolve amorphous Fe oxides by addition of Tamm's reagent prepared as described in part B. Test tubes are shaken intermittently f o r 12 hours and allowed to s e t t l e for 12 hours. The suspension i s then centrifuged, the supernatent l i q u i d decanted and residues washed with 10 ml d i s t i l l e d water prior to treatment with the dithionite-citrate-bicarbonate (dithionite) buffer. Dithionite extraction of c r y s t a l l i n e Fe oxides at pH 7.0 requires 8 ml of 0.3 M sodium c i t r a t e (88 g/1 dihydrate) and 2 ml of 1 a sodium bicarbonate (84 g/1), and warming i n a water bath to 80°C., The f i r s t of three successive additions of sodium d i t h i o n i t e powder i s added, and solution temperature i s maintained below 80°C to avoid p r e c i p i t a t i o n of ferrous sulphide. Following each d i t h i o n i t e addition, contents of the test tube are homogenized and allowed to stand for 6 minutes i n the water bath prior to the next addition. On completion of the 63 treatment, the suspension i s centrifuged, the supernatent l i g u i d i s decanted, and the residue i s washed with d i s t i l l e d water. An important consequence of the d i t h i o n i t e extraction i s the p r e c i p i t a t i o n of many trace elements as sulphides. Resolution i s achieved by addition of 9 ml of 30% hydrogen peroxide (w/v). The suspension i s shaken at random i n t e r v a l s over a 3 hour period to ensure samples do not become compacted. Remaining hydrogen peroxide i s destroyed by heating i n a 90°C steam bath for four hours. Flocculation of clays i s effected by addition of 1 ml of 10X (w/v) sodium chloride. Sample solutions are decanted following centrifuging and residues are washed with 10 ml of 1.09S (w/v) sodium chloride s o l u t i o n . The sequential extraction procedure i s terminated by treatment of sample residues with 10 ml of a 4:1 mixture of n i t r i c / p e r c h l o r i c acids followed by evaporation to dryness i n a 200°C a i r bath., Prio r to analysi s , t h i s f i n a l residue i s leached by 2.5 ml of warm, 6M hydrochloric acid and diluted to 10 ml with d i s t i l l e d water. 4. Sand content Following the n i t r i c / p e r c h l o r i c acid ' t o t a l ' digestion or the concluding stage of the sequential extraction, residues are quantitatively transferred to 270 mesh sieves. Samples are then placed i n a water bath and fine s displaced through the mesh by ultraso n i c vibration. The +270 mesh ( 5 3 micron) f r a c t i o n i s dried and weighed. 5. S o i l pH determination Ten grams of minus 10 mesh a i r dried s o i l are placed i n an 64 85 ml paper cup and 10 ml of d i s t i l l e d water i s added., The suspension i s s t i r r e d four times at 10 minute in t e r v a l s using a disposable p l a s t i c rod and then allowed to s e t t l e for 30 minutes. pH i s determined using a glass and calomel reference electrode pair and an Orion model 404 pH meter. Organic s o i l s may require addition of up to 40 ml of d i s t i l l e d water to f u l l y saturate 10 g samples, an exception to the standard 10 ml mixing volume. 6. Organic matter content Organic matter content i s estimated by weight loss on i g n i t i o n (LOI) of oven-dried samples (110°C) after i g n i t i o n i n a muffle furnace for 3 hours at 500°C. Uncertainty regarding possible loss i n weight from breakdown of sample carbonates i s not considered important as long as temperatures do not exceed 500°C. However the ef f e c t of water loss from clay minerals may be an important consideration, p a r t i c u l a r l y for inorganic samples (Hackereth, 1966). Disregarding possible e f f e c t s of these factors, LOI measurements r e f l e c t organic carbon content of a sample. Carbon determination by the Leco method i s described by Lavkulich (1974); A 0.05 to 1.0 g oven dried sample i s placed i n a c r u c i b l e and Fe and Sn f i l i n g s are added. The mixture i s homogenized and placed i n an induction furnace. Organic matter i s burned and after corrections for ambient temperature and pressure, the concentration of evolved carbon dioxide i s converted to a sample carbon content. The carbon content i s a measurement r e f l e c t i n g both organic and carbonate components. 65 Organic carbon content i s obtained by difference i f the carbonate concentration i s known from other experiments. 7. Size f r a c t i o n analysis P r i o r to size f r a c t i o n analysis, 1.0 g samples (2.0 g for samples with a high sand content) are treated with sodium hypochlorite, d i t h i o n i t e and hydrogen peroxide according to the sequential extraction procedure. Samples are wet sieved to -270 mesh, aided by ultrasonic vibration to separate s i l t and clay from sand, which i s retained by the sieve and weighed. The fine f r a c t i o n s are passed through a Sharpies centrifuge. The >2 micron s i l t f r a c t i o n remains on the l i n e r of the centrifuge, whereas the <2 micron clay f r a c t i o n passes through the Sharpies i n a water suspension. The <2 micron suspension i s adjusted to a volume of 250 ml with d i s t i l l e d water and s t i r r e d . A 50 ml aliquot i s evaporated to dryness and weighed, the weight representing 20% of the clay f r a c t i o n . & s i m i l a r procedure i s used to determine the >2 micron f r a c t i o n . However t h i s measurement i s l e s s r e l i a b l e inasmuch as losses are encountered i n cleaning the l i n e r . 8. Clay mineral i d e n t i f i c a t i o n Three s l i d e s are required for clay mineral i d e n t i f i c a t i o n (Lavkulich, 1974). Samples on two s l i d e s are treated with magnesium acetate followed by magnesium chloride to homoionically saturate the clay minerals. X-ray d i f f r a c t i o n patterns are obtained from one s l i d e without further treatment whereas the other i s subjected to a glycero l atmosphere for 24 66 hours pr i o r to X-ray examination. The t h i r d s l i d e i s run afte r saturation with potassium chloride and then rerun after heating to 300°C for 4 hours and rerun again af t e r reheating the s l i d e to 550°C for 4 hours. B. Stream, spring and lake water samples Sample treatment has been described by Fletcher (1971). A 250 ml aliguot containing 3 ml of concentrated hydrochloric acid i s placed i n a 400 ml Pyrex beaker, set on a hotplate and evaporated u n t i l only 15 ml of l i g u i d remain. The solut i o n i s transferred to a volumetric flask and diluted to 2 5 ml with d i s t i l l e d water. I l l ANALYTICAL TECHNIQUES A. Emission spectroscopy A ground or -80 mesh sieved i g n i t e d (at 550°C) sample i s mixed with an egual weight of graphite containing 50 ppm In as in t e r n a l s t a n d a r d ; T h e mixture i s loaded into a graphite cup electrode, sealed with sugar solution and excited by a 12 ampere DC arc for 20 seconds. Operating conditions are l i s t e d i n Table XI. Spectra are recorded on spectrographic plates and element concentrations estimated by vi s u a l comparison with master plates of known concentration which are prepared under i d e n t i c a l conditions. The density of the In l i n e provides a check on burn qu a l i t y . , Sr, Ba, Cr, Co, Ga, Ag, V, T i , B i , Sn and Sb are determined by a semi-quantitative spectrographic procedure s i m i l a r to that described by Nichol and Henderson-Hamilton (1965). Concentrations of 15 elements are reported over a range 67 of 1 to 10,000 ppm i n Table XII. Organic matter contents are estimated by LOI determinations p r i o r to spectrographic analysis. B. Atomic absorption spectrophotometry The theory and operation of atomic absorption spectrophotometry i s described elsewhere (Abbey, 1967). Techtron AA4 and Perkin Elmer model 303 instruments were used for a l l measurements. An instrumental procedure has been described by Fletcher (1971). Operating conditions are summarized on Table XIII. Hater samples and digests of stream and lake sediment, s o i l s and bogs are analyzed routinely by air-acetylene atomic absorption spectrophotometry for cne or more of the following elements: Cu, Zn, Ho, Fe, Hn, Pb and Ag (Table XIV). Ho i s routinely determined c o l o r i m e t r i c a l l y (see below), however, t h i s procedure i s not possible in hypochlorite and d i t h i o n i t e extracts because of the f a i l u r e of the organic phase to separate. Conseguently He i s determined by atomic absorption using a nitrous oxide-acetylene flame. Addition of aluminum (0.5 ml of 2.4% aluminum t r i c h l o r i d e hexahydrate to a 5 ml aliguot) as a releasing agent i s necessary prior to analysis (Kerbyson and Ratzkowski, 1970); P r e c i p i t a t i o n of aluminum hydroxide i s avoided by a c i d i f i c a t i o n with 0.5 ml of 1.5 H hydrochloric acid. However t h i s treatment may pre c i p i t a t e humic acid substances from organic-rich samples. The scavenging a b i l i t y of t h i s gelatinous material was evaluated by the method of standard addition and i t does not appear to re t a i n Ho. 68 Table XI Spectrographic eguipment and standard operating conditions S p e c t r o g r a p h S o u r c e i j A r c / S p a r k s t a n d I M i c r o d e n s i t o m e t e r i i A n o d e j ! C a t h o d e [ 3 - s t e p n e u t r a l f i l t e r N e u t r a l f i l t e r E m u l s i o n W a v e l e n g t h r a n g e M a s k S l i t w i d t h A r c c u r r e n t A r c g a p E x p o s u r e t i m e P l a t e p r o c e s s i n g P l a t e p r o c e s s i n g P l a t e p r o c e s s i n g P l a t e d e v e l o p m e n t H i l g e r - W a t t s A u t o m a t i c Q u a r t z S p e c t r o g r a p h L e c t r o - m a t i c p r o d u c t s ( A R L ) , M o d e l P 6 K S , T y p e 2 R 4 1 S p e x I n d u s t r i e s # 9 0 1 0 A R L S p e c t r o l i n e S c a n n e r # 2 2 0 0 G r a p h i t e , N a t i o n a l L 3 7 0 9 S P K G r a p h i t e , N a t i o n a l L 3 8 0 3 A G K S S p e x I n d u s t r i e s # 1 0 9 0 ; 5 % , 2 0 % , a n d 1 0 0 % t r a n s m i t t a n c e S p e x I n d u s t r i e s # 9 0 2 2 ; 2 0 % t r a n s -m i t t a n c e S p e c t r u m a n a l y s i s #1 2 7 7 5 t o 4 8 0 0 a n g s t r o m s 17 mm 15 m i c r o n s 12 a m p e r e s u mm 20 s e c o n d s D e v e l o p e r K o d a k D - 1 9 a t 2 3 ° C D e v e l o p e r K o d a k D - 1 9 a t 2 3 ° C S t o p b a t h K o d a k 30 s e c o n d s 3 m i n u t e s 69 T a b l e XII O p e r a t i o n c h a r a c t e r i s t i c s and p r e c i s i o n a t t h e 95% c o n f i d e n c e l e v e l o f e m i s s i o n s p s c t r o m e t r i c a n a l y s i s ( D o y l e , 1971) Element S p e c t r a l l i n e Ave r e a d i n g P r e c i s i o n Angstroms ±% Sr 4607.33 1280. 85 Ba 4554.04 1320. 90 Cr 4254.35 8.0 90 Co 3453.51 8.5 80 N i 3414.77 7.9 85 T i 3372.80 1400. 60 Cu 3273.96 16.1 50 I n 3256.09 25.5 45 V 3185.40 53.5 60 Ga 2943.64 16. 35 Pb 2833.07 4.1 95 Mn 2801.06 273. 85 Tabla XIII O p e r a t i o n a l c h a r a c t e r i s t i c s of atomic a b s o r p t i o n a n a l y s i s Techtron AA4 Perkin Elmer 303 Element Wavelength Angstroms S l i t u Width A Current ma S l i t Scale H Lamp in/out • Range F i l t e r in/out Current ma Ho 3132.6 100 3.3 5 Cu 3247.5 50 1.7 3 a 1 - uv - 14 Zn 2138.6 100 3.3 6 5 1 - uv - 14 Fe 3719.9 25 0.8 5 3 1 - uv - 20 Hn 2794.8 50 1.7 10 a 1 - uv 15 Pb .: 2170.0 . 4 2 * uv 14 3280.7 4 10 • uv - . 6 Table XIV Summary o f e l e m e n t s d e t e r m i n e d f o r d i f f e r e n t s t u d y a r e a s a n d e x t r a c t i o n p r o c e d u r e s S t u d y a r e a E x t r a c t i o n p r o c e d u r e A n a l y s i s methods C Z F H N P A C H S B C T V G T B S S t C S X C u n e n o b q o i r a r n a i i n b o a r a i n d r d b R e c o n n a i s s a n c e R e c o n n a i s s a n c e (BTZ) R e c o n n a i s s a n c e (OBC) C a p o o s e Lake G r e e n Lake F i s h and P o r t n o y L a k e s L a k e c o r e s - a l l a r e a s A l l a r e a s A l l a r e a s A l l a r e a s I g n i t i o n t o 550°c EmSpec" N i t r i c / p e r c h l o r i c AAS» H i t r i c / p e r c h l o r i c A A S . C o l * N i t r i c / p e r c h l o r i c A A S , C o l , l e c o * H i t r i c / p e r c h l o r i c A A S , C o l , L e c o H i t r i c / p e r c h l o r i c A A S , C o l , L e c o H i t r i c / p e r c h l o r i c AAS.Col C o l d e x t r a c t i o n s AAS,Col S e q u e n t i a l e x t r a c t i o n s AAS,Col S i z e f r a c t i o n a n a l y s i s AAS.Col X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X ( X X X X X X X X X X X X » e n i s s i o n s p e c t r o s c o p y * a t o n i c a b s o r p t i o n s p e c t r o s c o p y 1 c o l o r i a e t r y , no by l i n e d i t h i o l • L e c o o r g a n i c c a r b o n d e t e r a i n a t i o n 72 a OBC standard rock, two duplicate samples and a blank are included with each batch of 32 samples- a n a l y t i c a l r e s u l t s are treated by a method given i n Stanton (1966); Precision at the 95% confidence l e v e l on paired sample analyses are computed on the IBB 370/168 according to a procedure outlined by Garrett (1969; 1973), and programmed by Fox (1971). Duplicate s o i l analyses following n i t r i c / p e r c h l o r i c acid treatment give precision values of ±251 or better at the 95% confidence l e v e l . Precision of seguential extraction data are poor compared to • t o t a l * determination values, probably as a conseguence of the large number of steps i n the experimental procedure, where average metal values are near the detection l i m i t , precision i s invar i a b l y poorer s t i l l . Nevertheless precision i s commonly better than ±40% for most elements (Table XV). C. , Colorimetry Mo determinations are performed c o l o r i m e t r i c a l l y using zinc d i t h i o l wherever possible (Stanton, 1966). Modification of the procedure by addition of acetone to organic-rich sample aliguots i s necessary to ensure separation of the organic phase (Hoffman and iaskett-Myers, 1974). For analysis of Mo i n water, a second colorimetric method employing thiocyanate i s reguired (Delavault, procedure modified after Sandell) because n i t r i c acid used i n f i e l d a c i d i f i c a t i o n oxidizes the d i t h i o l reagent. 7 3 Table XV P r e c i s i o n o f ato m i c abs o r p t i o n a n a l y s i s a t t h e 9 5 % c o n f i d e n c e l e v e l e s t i m a t e d by a n a l y s i s o f p a i r e d samples Extraction procedure Element Average Precision number of Concentration t% Samples ppm Sodium hypochlorite Cu 11.3 31.9 22 Zn 2.68 81.5 22 Fe 194. 93.4 22 Hn 10tt. 13.4 22 Do 0.98 41.4 22 Disti l l e d water Cu 0.51 115. 22 Zn 2.57 49.9 22 Fe 20.66 122. 22 Hn 32.11 32.9 22 Bo 0.02 463. 22 Hydroxylamine Cu 1.06 92.6 22 hydrochloride Zn 2.i»6 28.8 22 Fe 69.3 41.5 22 Bn 195. 44.3 22 Ho 0.00 5940* 22 Acid ammonium oxalate Cu 16.9 17.9 22 Zn 13.1 101.6 22 Fe 8000. 23.6 22 Hn 100. 18.7 22 Ho .32 42.8 22 Citrate-dithionite- Cu 0.25 550. 21 bicarbonate Fe 8000. 36.6 21 Bn 56.6 22.6 21 Bo 10.8 36.6 21 Hydrogen peroxide Cu 9.51 24. 1 21 Zn 35.7 39.0 21 Fe 199. 47.2 21 Hn 11.5 32.0 21 Bo O.OH 1700. 21 Hitric-perchloride Cu 31.0 8.7 19 acid digestion of Zn 36.3 26.4 19 residues FeX 1.21 14.4 19 Hn 147. 16.1 19 Bo 0.10 660. 19 Sand 0.35 9.7 19 nitric-perchloric Cu 109. 10. 10 acid digestion of Zn 401. 23.5 10 lake core samples FeS 3.68 22.6 10 Bn 880. 8.0 10 Ho 18.0 151. 10 Sand 0.12 210. 10 Kitric-perchloric Cu 54. 10.3 53 acid 'total* Zn 83. 16.0 50 digestion Fe* 2.4 14.3 53 Hn 365. 13.5 53 Pb 25. 31.8 36 Ho 6.8 22.7 53 Ag 1.5 8.6 14 Hater samples after CU 5. 49. 22 10 fold concentration Zn 16. 52. . 22 Fe 910. 22. 22 Hn 165. 25. 22 Ho 1. 300. 22 Duplicate analysis Cu 506. 7.3 24 of s i l t and clay Zn 302. 14.2 24 fractions - n i t r i c FeS 1.43 17.8 24 and perchloric acid Hn 331. 10.0 24 digestion Ho 0.22 24.5 24 Pb 64. 47.3 24 74 CHAPTER 5 PARTIAL AND SEQUENTIAL EXTRACTION EXPERIMENTS I PARTIAL EXTRACTION TECHNIQUES A. Introduction The syngenetic or epigenetic character of a geochemical anomaly often can be determined by examining partioning of a metal among the various s o l i d phases present i n a sample. Chemical reagents which dissolve only a readily soluble f r a c t i o n of trace elements may amplify contrast between mineralized and background areas ( E l l i s et a l , 1967) because a high proportion of metal ions derived by oxidation of sulphide minerals are held i n low energy bonding positions adsorbed onto and within secondary minerals. Therefore weaker extractions may be of greater value i n defining epigenetic (hydromorphically-derived) anomalies than digestions which dissolve * t o t a l * metal., By comparison, syngenetic (mechanically-derived) components of the • t o t a l * metal content r e f l e c t metal-rich primary minerals. However conclusive evidence of a syngenetic c l a s t i c o r i g i n of an anomaly i s indicated only by presence of d e t r i t a l grains of ore minerals. Many ore minerals and primary s i l i c a t e minerals are unstable i n the s u r f i c i a l environment. On weathering a f r a c t i o n of the ' t o t a l 1 metal content i s l i b e r a t e d , and may accumulate either i n association with secondary minerals or be washed out of the system i n solution. Consequently p a r t i a l extraction experiments on syngenetic anomalies can also y i e l d high p a r t i a l extractable metal to ' t o t a l * metal r a t i o s . Further, high r a t i o s 75 may characterize background samples which have been subjected to intense weathering processes. B. Selection of reagents Hydromorphic enrichment of Cu, Zn, Mo, Pe and fin i n s o i l s , stream sediments and lake sediments proceeds via chemical interactions between ground or subsurface waters and various sample f r a c t i o n s . Scavenging by organic matter and amorphous Fe and Mn oxides i s the most common mechanism for hydromorphic enrichment (Horsnail et a l , 1969; Horsnail and E l l i o t t , 1971). However cation exhange reactions associated with clay minerals, or p r e c i p i t a t i o n reactions promoted by carbonate minerals are processes which can lead to anomalous accumulation of trace metals. Because trace elements commonly are concentrated by several sample f r a c t i o n s * a wide variety of reagents are employed to dissolve s p e c i f i c f r a c t i o n s of a sample, simultaneously releasing associated trace elements. Four p a r t i a l extractants were chosen for the present work: cold d i l u t e hydrochloric acid (0.5 M), ethylenediamine t e t r a a c e t i c acid (EDTA), neutral ammonium acetate and acid ammonium oxalate. Cold d i l u t e hydrochloric acid commonly i s chosen (Sorenson et a l * 1971; Maynard and Fletcher, 1973; Rose, 1975) because the reagent dissolves or partly dissolves most s o i l and sediment f r a c t i o n s having the a b i l i t y to ret a i n elements deposited from subsurface or ground waters. S i l i c a t e minerals are not dissolved. However d i l u t e hydrochloric acid i s a nonselective reagent and p a r t i a l l y attacks many of the po t e n t i a l l y active sample f r a c t i o n s : organic matter, Fe and Mn oxides, clay 76 minerals and carbonate minerals. Therefore data r e f l e c t an over a l l epigenetic character of a sample. Although d i l u t e hydrochloric acid lacks s p e c i f i c i t y , i t s application i n exploration i s based on the fact that the experimental procedure i s r e l a t i v e l y simple, and extracts are amenable to col o r i m e t r i c analysis i n the f i e l d ; EDTA i s employed to remove ions from exchange s i t e s on clays and other sample fractions (Thierweiler and Lindsay, 1969; Hose, 1975), or to compete with organic f r a c t i o n s i n complexing trace elements held i n organic matter (Maynard and Fletcher, 1973). This i s accomplished by complexing the trace i o n i n solution. Metal ions of s o l i d phases subsequently are released to achieve an equilibrium state. A buffer solution pH of 4.7 controls the complexing reaction by avoiding decomposition or dis s o l u t i o n of mineral f r a c t i o n s under more acidic conditions, and by avoiding deposition of released trace elements under more alkaline conditions. However at pH 4.7, EDTA dissolves some organic matter which i s also capable of acting as a complexing agent. Carbonates, and a f r a c t i o n of the Fe and Mn associated with oxide phases are also dissolved. However EDTA i s not s u f f i c i e n t l y strong to leach many trace elements bound within s i l i c a t e l a t t i c e s ; Neutral ammonium acetate o f f e r s a second method of estimating extent of trace element association with exchange s i t e s . The reagent, at a 1 M strength, provides abundant ammonium ions which replace exchangeable cations i n a sample (Coleman et a l , 1959); Although most studies using neutral ammonium acetate centre on the clay component, presumably metals associated with exchange s i t e s of other fract i o n s are also released. Time-required for eguilibrium between ammonium ions and sample cations i s i n the order of seconds, though oxide coatings lengthen time required to reach equilibrium to several minutes (Kennedy and Brown, 1966). Trace element content associated with exchange s i t e s i s commonly low (Haynard and Fletcher, 1973), and values are at or below the detection l i m i t of atomic absorption. Acid ammonium oxalate (Tamm's reagent) i s employed to estimate content of amorphous Fe and Mn oxides in overburden samples (LeRiche and Se i r , 1963; HcKeague and Day, 1966; Gamble and Daniels, 1972); The reagent has also been suggested f o r determination of Ho content available to plants i n s o i l s (Reisenauer, 1965). Acid ammonium oxalate reduces oxidized forms of Fe and Kn, held i n amorphous or poorly c r y s t a l l i n e oxide phases, to soluble ferrous and manganous ions (Rose, 1975). Once f e r r i c iron i s reduced, oxalate ions of the buffer (pH 3.5) complex the metal and keep i t i n solution. Quantity of Fe and Mn extracted by acid ammonium oxalate depends on experimental conditions. Strength of extraction of a given molarity of Tamm*s reagent i s affected by presence or absence of u l t r a v i o l e t l i g h t (DeEndredy, • 1963; HcKeague and Day, 1966),and by length of the extraction i n t e r v a l . Although the extraction i s designed to be s p e c i f i c for amorphous Fe and Mn oxides, minor amounts of amorphous or poorly c r y s t a l l i n e clay minerals are simultaneously s o l u b i l i z e d . Nevertheless the treatment leaves most of the clay size f r a c t i o n r e l a t i v e l y unaffected (Dion, 1944; Harward et a l , 1962)., However carbonate 78 minerals and organic matter are dissolved i n large q u a n t i t i e s . Solution of organic matter i s p a r t i c u l a r l y s t r i k i n g because i t imparts a brown colour to extracts. C. Geochemical r e s u l t s P a r t i a l extraction experiments were performed only on lake sediment samples. Data are divided into 7 groups (Fig 13) according to sample location (Fig 4). Groups 1, 2 and 3 are comprised of sediments taken from d e l t a i c , nearshore and basinal environments, respectively, i n Capoose lake. Samples contain above average or anomalous concentrations of Cu, Zn and Mo, and are also enriched i n Fe and Mn. Group 4 consists of organic-r i c h , Fe and Mn-poor samples col l e c t e d from the Fish Lake Cu -Mo anomaly. Groups 5, 6, and 7 are composed of organic-rich sediment from Baxter, Canoe and Haskett Lakes, respectively, and represent background Cu, Zn and Mo concentrations. Samples from anomalous lakes respond d i f f e r e n t l y t o p a r t i a l extractions than those from background areas. Dilute hydrochloric acid, EDTA and acid ammonium oxalate leachates of groups 5, 6 and 7 samples are more highly coloured, and sediment more dispersed than'corresponding solutions from group 1 to 4 samples. Despite such v i s i b l e differences, and the f a c t that average ' t o t a l * metal l e v e l s of anomalous lakes may be 7X (or more) greater than average »total* metal contents of background lakes, a si m i l a r percentage of the " t o t a l * Cu, Zn, Fe and Mn i s extracted from sediments of each group. Moreover, percentage extraction of Cu and Zn from background samples commonly exceeds corresponding figures from anomalous samples. 79 Dilute hydrochloric acid i s usually the strongest of the four reagents, removing an average of 50 to 70% of the * t o t a l * Cu and Zn, 30 to 10% of the Fe, and 50 to 80% of the Mn. By contrast, less than 15% of the • t o t a l 1 Mo i s dissolved. Percentage extraction of Fe and Mn from Fe-rich Capoose Lake does not d i f f e r appreciably from percentage extraction of these elements from organic-rich sediments, despite the fact that Fe and Mn contents are as much as 5X and 23X greater, r e s p e c t i v e l y , i n Capoose Lake. S i m i l a r l y , although average Mo contents of groups 3 and greatly exceed the regional threshold of 9 ppm (29 ppm and 18 ppm, re s p e c t i v e l y ) , detectable l e v e l s of Mo are not extracted from samples of the l a t t e r group. Solution of Cu, Mo, Fe and Mn by EDTA i s similar to that by acid ammonium oxalate. However metal extraction by both reagents averages 5 to 20% lower than i n d i l u t e hydrochloric acid. EDTA i s s l i g h t l y more e f f i c i e n t than Tamm*s reagent i n dissolving Zn and Mn, whereas acid ammonium oxalate i s more ef f e c t i v e in dissol v i n g Cu, Fe and Mo. Both reagents dissolve only a small f r a c t i o n of the • t o t a l t Mo content. Conseguently, Mo, as well as Cu and Zn, do not appear to accumulate i n a manner which i s amenable to sel e c t i v e p a r t i a l extraction by either reagent. Both reagents also f a i l to improve anomaly contrast compared to • t o t a l 1 data. By comparison to the preceeding 3 reagents, neutral ammonium acetate i s a very poor s o l u b i l i z i n g agent for a l l elements except Mn. Concentrations of many trace elements are near the detection l i m i t of atomic absorption, p a r t i c u l a r l y f o r background samples. Comparison of background and anomalous 80 samples under these conditions i s therefore meaningless, and neutral ammonium acetate i s unsuccessful i n discriminating samples from either group., Although 15 to 30$ of the • t o t a l * Hn content i s dissolved by t h i s reagent, anomaly contrast i s not improved. E. Discussion The premise that p a r t i a l extractions w i l l s e l e c t i v e l y dissolve epigenetic components of the * t o t a l * Cu, Zn or Ho content, a property which might be correlated with the anomalous character of a sample, cannot be substantiated for the case of lake sediment data; Despite widely varying concentrations of these metals, as well as greatly f l u c t u a t i n g guantities of f e , Mn and organic matter, lakes anomalously r i c h i n cu, Zn and Mo are not d i f f e r e n t i a t e d from lakes containing only background l e v e l s of these elements. Lakes r i c h i n Fe and Mn and/or organic matter also cannot be distinguished from lakes r e l a t i v e l y poor i n these sediment f r a c t i o n s . Further, as w i l l be shown i n Chapter 6, differences i n the r e l a t i v e proportion of c l a s t i c and dissolved inputs to a lake, or variable distances between a mineral occurrence and a lake may not be major factors insofar as Cu,-Zn, Ho, Fe and Mn e x t r a c t a b i l i t y from lake sediment i s concerned. , Background lake sediments appear to retain Cu, Zn and Mo i n an analogous fashion to anomalous lake sediments. Extraction of these elements and Fe and Mn by d i l u t e hydrochloric a c i d , EDTA and acid ammonium oxalate accounts for approximately 50% of •t o t a l * concentrations. This percentage i s greater than might 81 be expected i f the p a r t i a l extraction was dissolving only hydromorphic components of the * t o t a l * content r e f l e c t i n g mineralized bedrock. Enhanced extraction probably indicates these reagents leach samples i n a vigorous fashion as a consequence of the highly weathered character of sediments from both anomalous and background areas. Evidently weathering i s a more important process than hydromorphic dispersion from mineralized bedrock, and trace elements associated with several sample f r a c t i o n s are libe r a t e d simultaneously., In contrast, the four reagents are unable to dissolve more than a minor amount of Ho. This suggests that Mo i s more strongly bound than Cu or Zn, and indicates that i f Mo anomalies i n lakes have a hydromorphic genesis, a stronger p a r t i a l extractant i s required to estimate the epigenetic component of Ho i n lake sediment. P a r t i a l extractions often distinguish between anomalous and background samples (page 151, Hawkes and Webb, 1962; page 245, Levinson, 1974). Nevertheless p a r t i a l extractants can dissolve s i m i l a r proportions of the • t o t a l * metal content from anomalous and background samples (Gleeson and Coope, 1966; Haynard and Fletcher, 1973). Samples, comprised predominently of f i n e l y divided organic matter, amorphous f r a c t i o n s , and clay minerals, appear to reta i n metals i n a loosely bonded manner. Much emphasis i s placed on chemical properties and Eh - pH character of the extracting reagent (Rose, 1975). L i t t l e concern i s given to mechanisms of the extraction process and influence of supposedly inert components of the sample. For example, Tamm's reagent i s supposed to operate by reducing the Fe content of amorphous Fe oxides to i t s ferrous state and by 8 2 complexing t h i s ion with oxalate species. Trace elements associated with amorphous Fe oxides are presumably simultaneously s o l u b i l i z e d . However humic and f u l v i c acids may also be l i b e r a t e d from organic-rich sediments; and may act as complexing agents much in the fashion as described for EDTA. Consequently add i t i o n a l s o l u b i l i z a t i o n of Cu, Zn and Ho, as well as Fe and Hn, by organic matter chelates i s to be expected in organic-rich samples. Enhanced extraction due to organic complexing agents i s unlikely to be constant from lake to lake because the guantity and chemical character cf organic matter i s highly variable between and within lakes. Acid conditions of the extraction (pH 3;5) favour carbonate solution and release of associated trace elements. In minor quantities the carbonate f r a c t i o n does not exert a great influence on trace metal l e v e l s . In carbonate-r i c h samples, simultaneous release of metals held by carbonate minerals, and displacement of buffer pH to more a l k a l i n e values w i l l greatly a f f e c t e f f i c i e n c y of Tamm*s reagent. Similar factors influence d i l u t e hydrochloric acid and EDTA extractions. V a r i a b i l i t y i n trace metal extraction related to v a r i a b i l i t y i n bulk composition of lake sediments has not been studied i n d e t a i l . Preliminary data suggest widely varying contents and chemical character of organic matter may have a pronounced and heterogeneous influence on p a r t i a l extractions. Enhanced extraction may be related to chemical properties of organic matter associated with an i n d i v i d u a l lake rather than a parameter i n d i c a t i n g unusually high le v e l s of epigenetic metal. Consequently, information on sediment appearance and properties 83 are necessary to assess p a r t i a l extraction data. I I SEQUENTIAL EXTRACTION TECHNIQUES A. Introduction In view of problems associated with v a r i a b i l i t y i n lake sediment composition, and n o n - s p e c i f i c i t y of many of the commonly employed p a r t i a l extractants, an experimental procedure was designed to extract sequentially trace elements from s p e c i f i c sample f r a c t i o n s . Reagents were chosen t o maximize sel e c t i v e d i s s o l u t i o n of trace elements associated with each sample f r a c t i o n , and minimize heterogeneous release of metals bound i n other f r a c t i o n s . Hajor problems encountered i n the preceeding p a r t i a l extraction study are characterized by a r e l a t i v e l y constant release of Cu, Zn, Fe and Hn from anomalous and background lakes, and by the r e l a t i v e i n s o l u b i l i t y of Ho i n the same reagents. Simultaneous release of soluble organic compounds under a c i d i c conditions of the d i l u t e hydrochloric acid, EDTA, and acid ammonium oxalate extractions i s another problem suspected of enhancing trace element l i b e r a t i o n from samples containing organic matter. Consequently, organic matter removal i s a necessary i n i t i a l step i n any sequential extraction procedure. Once organic matter i s removed, sample carbonates must be dissolved to ensure a c i d i c buffer solutions of succeeding extractions are not displaced to more alkaline conditions. Methods to s o l u b i l i z e carbonates unavoidably are accompanied by release of very weakly bound metal, and solution of hydroxide pre c i p i t a t e s . Fe and Hn oxides are next most soluble of 84 remaining sample f r a c t i o n s . Because degree of c r y s t a l l i n i t y of t h i s sample component i s variable, solution can be affected i n stages, and trace elements, as well as Fe and Hn, can be dissolved as a function of the strength of applied reagent. Presumably the most soluble phases are amorphous or poorly c r y s t a l l i n e . , Such material i s a p o t e n t i a l l y active scavenging agent for metals such as Cu, Zn and Ho. In contrast, the l e a s t soluble oxides l i k e hematite and magnetite are highly c r y s t a l l i n e . Presumably they are l e s s able to scavenge trace elements. Solution of Fe and Mn oxides under weakly a c i d i c conditions ensures s i l i c a t e minerals of the residue, p a r t i c u l a r l y clays, are not dissolved appreciably or transformed to new minerals. Dissolution of remaining s i l i c a t e phases provides an estimate of the syngenetic trace element content of a sample. £. Choice of reagents and order of sample treatment (Fig 12) 1. Sodium hypochlorite, pH 9.5 Sodium hypochlorite, freshly adjusted to pH 9.5, i s an oxidizing agent (Rose, 1975) which decomposes a large proportion of the sample organic matter i n a fashion s i m i l a r to hydrogen peroxide (Lavkulich and Hiens, 1970). Hypochlorite i s superior for routine applications because the reaction i s not as strongly effervescent as i s the hydrogen peroxide oxidation. Although hypochlorite also oxidizes sulphide minerals, moderate a l k a l i n i t y deters possible s o l u b i l i z a t i o n of Fe and Mn oxides, and with the exception of a small amount of Mn which i s oxidized to permanganate (Anderson and O'Conner, 1972), Fe and Mn oxides 85 are not dissolved;. Hypochlorite does not modify c r y s t a l l i n e clay minerals appreciably (personal coot, Lavkulich, 1974), and solution pH i s too al k a l i n e to s c l u b i l i z e sample carbonates. Extracts are highly coloured, i n d i c a t i n g release of a s i g n i f i c a n t guantity of humic acids which are commonly considered trace element complexing agents (Chowdhury and Bose, 1971; Bashid, 1972). Once trace elements are liberated from organic matter and sulphide minerals, pH of the hypochlorite solution i s s u f f i c i e n t l y a l k a l i n e to cause many elements to precipitate as basic metal hydroxides unless they are retained i n s olution as complexes with humic acids. In addition, humic acids may leach trace elements from remaining s o l i d f r a c t i o n s . Al t e r n a t i v e l y , remaining fract i o n s may scavenge trace elements from solution. For purposes of t h i s t h e s i s these two facto r s are assumed of n e g l i g i b l e importance. 2. A c i d i f i e d d i s t i l l e d water, pH 3.0 (dilute hydrochloric acid) Many trace elements released on p a r t i a l oxidation of organic matter and sulphide minerals may precipitate as basic hydroxides because of the alkaline conditions of the hypochlorite extraction. Precipitates are redissolved by lowering the solution pH to a c i d i c l e v e l s . However carbonate minerals are simultaneously dissolved and associated trace elements are l i b e r a t e d . Although cation exchange reactions are minimized by maintaining the solution pH at 3.0, exchangeable metals are p a r t i a l l y displaced by hydrogen ions. Conseguently, metal contents of a c i d i f i e d d i s t i l l e d water leachates r e f l e c t the sum of the trace element contents associated with basic 8 6 hydroxide p r e c i p i t a t e s , carbonate minerals, and exchange s i t e s . Lowering the pH below 3.0 increases r i s k of increased s o l u t i o n of Fe and Hn oxides and clay minerals, and simultaneous release of associated trace metals. 3. Hydroxylamine hydrochloride, pH 2.5 Hydroxylamine hydrochloride i s a reducing agent which dissolves the most amorphous forms of Hn and Fe oxides, provided duration of treatment i s short (Chao, 1972). fieaction conditions of pH 2.5 and leach i n t e r v a l of 30 minutes are chosen to minimize solution of amorphous Fe oxides which dissolve with longer leach durations, and s o l u b i l i z a t i o n of amorphous and c r y s t a l l i n e clay minerals (personal comm, Lavkulich, 1974). Basic hydroxides, i f precipitated during the hypochlorite extraction and not redissolved by a c i d i f i e d d i s t i l l e d water, might be redissolved by a combination of a c i d i c and reducing conditions. If basic hydroxides survive a c i d i f i e d d i s t i l l e d water and hydroxylamine hydrochloride extractions, t h e i r solution during subseguent steps of the sequential extraction would not be recognized. 4. Acid ammonium oxalate, pH 3.5 Application of acid ammonium oxalate at t h i s stage d i f f e r s from the p a r t i a l extraction of part I i n that a l l but the most insoluble forms of organic matter have been previously oxidized or dissolved by hypochlorite. Extracts exhibit only the c h a r a c t e r i s t i c yellow colour of f e r r i c Fe (probably caused by slow atmospheric oxidation of ferrous ions), with no variatio n s 87 attributable to humic acid substances. Tamm's reagent reduces oxidized forms of Fe and Hn i n amorphous or s l i g h t l y c r y s t a l l i n e oxide phases to more soluble ferrous and manganous ions.. Reaction conditions are controlled to avoid dissolving s i g n i f i c a n t guantities of c r y s t a l l i n e Fe oxides. 5. Citrate-bicarbonate-dithionite ( d i t h i o n i t e ) , pH 7.0 Dithionite i s commonly used to estimate the * t o t a l * guantity of Fe oxides (Kilmer, 1960) or proportion of amorphous and c r y s t a l l i n e Fe oxides i n s o i l s (Franzmeier, 19 65; HcKeague and Day, 1966; Gamble and Daniels, 1972). Occasionally, studies are reported on trace element release as a function of c r y s t a l l i n e Fe oxide solution (Kubota, 1965)• Anderson and Jenne (1970) indicate d i t h i o n i t e treatment i s necessary prior to separating the clay f r a c t i o n from coarser f r a c t i o n s of a s o i l sample, and K i t t r i c k and Hope (1963) have outlined a general procedure for disaggregating a sample prior to size f r a c t i o n analysis. Reaction conditions reguire buffering the sample at pH 7.0 and r a i s i n g the temperature to 80°C (Hehra and Jackson, 1960). This creates a strongly reducing environment capable of dissolving a l l but the most re s i s t a n t Fe and Hn compounds (Rose, 1975). Although d i t h i o n i t e dissolves c r y s t a l l i n e Fe oxide coatings from clay minerals, the reagent does not appear to disrupt t h e i r i n t e r n a l structure. 6. Hydrogen peroxide, pH 3.5 Hany trace elements precipitate as sulphides following 88 d i t h i o n i t e treatment, and must be redissolved using an oxidant. Hydrogen peroxide i s a convenient reagent. However extracts cannot be routinely analyzed for Zn because an ion i n s o l u t i o n , possibly sulphate ions, i n t e r f e r e s with Zn determination by atomic absorption (personal comm, Delavault, 1974) ..... 7. H i t r i c and perchloric acids Prio r to n i t r i c / p e r c h l o r i c acid digestion of the sample residue, trace metals associated with organic, carbonate and Fe oxide f r a c t i o n s are extracted. Consequently metals associated with coatings on sand and clay minerals have been removed, and n i t r i c / p e r c h l o r i c acids leach trace elements bound in remaining s i l i c a t e minerals.' This component of the sample i s referred to as * s i l i c a t e ' r e s i d u e * or * f i n a l residue* i n following sections. The sand content of the f i n a l residue i s estimated by sieving and weighing the plus 270 mesh f r a c t i o n . C. Geochemical r e s u l t s 1. Introduction Great d i v e r s i t y characterizes seguential extraction patterns of trace elements from s c i l s , stream sediments and lake sediments from the same area. V a r i a b i l i t y i s further increased by comparing extraction parameters for several areas, and by heterogeneity of sample media, such as s o i l s , which are comprised of a combination of organic and mineral f r a c t i o n s . To minimize v a r i a b i l i t y attributable to compositional f a c t o r s , s o i l s , stream, and lake sediments are divided into classes which are r e a d i l y i d e n t i f i e d by sample appearance. S o i l s are 89 separated by horizon into organic-rich *L-H', "Ah' and •Bh', and mineral-rich *Ae*, »Bf», 'Bt», *Bg*, *BCf, and 'C groups. Although stream sediments also can be c l a s s i f i e d into organic-r i c h and mineral-rich groups, the t o t a l number of stream sediment samples i s r e l a t i v e l y low, and data are presented for the media as a whole. Lake sediments are divided into 2 classes r e f l e c t i n g organic-poor and organic-rich sedimentary environments. The organic-poor group i s subdivided i n t o basinal, nearshore and d e l t a i c classes on the basis of sediment texture and proximity to inflowing streams. 2. S o i l s Cu, Zn, Ho, Fe, and Hn were extracted sequentially from s o i l s of the Capoose Lake, Green Lake, and Fish and Portnoy Lake areas (Figs 14 to 16). , In most of the study areas, hypochlorite dissolves 70 to 9536 of the Cu and Ho, and 15 to 65% of the Zn, Fe and Hn from 'L-H* samples, presumably metal held by organic matter (Table XVI). Despite these high l e v e l s , 10 to 65% of the • t o t a l ' content also appears contained i n the f i n a l residue (Table XVIII) j r e f l e c t i n g unavoidable c o l l e c t i o n of inorganic contaminants from underlying 'Ah», 'Ae', or •B1 horizons. Hypochlorite also dissolves 8 to 50% of the / t o t a l • Ho from mineral horizon samples. This probably r e f l e c t s the soluble nature of Ho under alkaline conditions. ' Acid ammonium oxalate (Table XVII), d i t h i o n i t e , and n i t r i c / p e r c h l o r i c acids (Table XVIII) dissolve large quantities of Cu, Zn, Ho, Fe, and Hn from mineral-rich samples. Cu and Zn concentrations associated with amorphous Fe oxides comprise an 100 1 6 8 0 U j g 60 Q _ S <_>8 OC . U J °- 20 V- 0 ioo; o 5 U J °- 20 0 100 UjS CO Q S C Q , _ CD 1 IS 20 0 GROUP NUMBER It II1 8 .100 50 10 5 , m tjmw 100 50 10 5 .il.nww 111. ll 3 5 7ll 5 5 7 s g 100 50 10 5 sssa. 1 3 5 7 |l 3 5 7 13 5 7 100 80 o O g 60 I 1 ^ rvifeio uj C J oc U J ° - 20 i Q 100 UJ= 8 0 ^ | e o J ^feio f X ^ _ . U J • c : — U J II A l i i t t 1000 E 503 O . 1 K 100 '50 • 10 o -I GROUP NUMBER 10000 E 5000 i a o I 1000 1 530 100 13 5 7 1 3 5 7 1 3 5 7 13 5 7 1 3 5 7 DILUTE EDTA HYDROCHLORIC ACID NEUTRAL ACID AMMO'IIL'H AMMONIUM ACETATE OXALATE NITRIC -PERCHLORIC 'TOTAL' DILUTE EDTA HYDP0CHL0RIC ACID NEUTRAL AMMONIUM ACETATE ACID AMMONIUM OXALATE NITRIC -PERCHLORIC 'TOTAL' PROUP 1: DELTAIC SEDIMENTS. CAP03SE LAKE (5 SAMPLES)! PROUP 2: HEARSII0RE SEDIMENTS. CAPOOSE LAKE (5 SAMPLES)i PROUP 3: CENTRAL LAKE SEDIMENTS. CAPOOSE LAKE (19 SAMPLES)! PROUP 1; FISH LAKE SEDIMENTS (5 SAMPLES)) GROUP 5: BAXTER LAKE SEDIMENTS (9 SAMPLES). GROUP 6: CANOE LAKE SEDIMENTS (23 SAMPLES)) GROUP 7: WASKETT LAKE SEDIMENTS (2 SAMPLES). > ANOMALOUS SAMPLES) l BACKGROUND SAMPLES) • NOT DETECTED. PERCENT EXTRACTION I S COMPARED TO A SEPARATE ' TOTAL ' DETERMINATION SYMBOL AND BAR INDICATE AVERAGE PERCENT EXTRACTION (CENTER OF SYMBOL) AND RANGE OF PERCENT EXTRACTION VALUES F I G U R E 1 3 : T R A C E E L E M E N T S O L U T I O N B Y D I L U T E H Y D R O C H L O R I C A C I D , E D T A / N E U T R A L A M M O N I U M A C E T A T E / A N D A C I D A M M O N I U M O X A L A T E ON S E L E C T E D L A K E S E D I M E N T S A M P L E S / N E C H A K O P L A T E A U / B . C . to o y x 100 £g 60 8:5 SS w 1 0 0 s 8 0 c u g 6 0 cc 20 0 1 0 0 S sea O t*J S t 1 0 a : 20 1 0 0 U J g 6 0 SB is * 2 0 0 ' 1 0 0 E g 6 0 O S 2 0 : o G R O W 5 0 0 1 0 0 5 0 l.» » ^ 1 0 0 50-R 1 " 5 M-4,... 1 * " i 0.5 0 . 1 0 . 0 5 1 0 0 0 I 5 0 0 UJ UJ | I * £ 5 0 A 1 3 5 7 9 1 3 5 7 1 0 0 S£ 1 0 S 5 1 3 5 7 9 1 3 5 7 1 3 5 7 9 .1... * J 1 3 5 7 1 3 5 7 9 1 3 5 7 S 0 D I H 1 A C I D I F I E D KYTROXYLAMINE A C I D HYPOCHLORITE D I S T I L L E D HYDROCHLORIDE A W B t l l U M WATER O X A L A T E D I T H I O N I T E HYDP.QfER PEROXIDE N I T R I C -PERCHLORIC A C I D S N I T R I C -PERC DORIC T O T A L * 6 R 0 U P 1 : l-H HORIZON ( 7 S A M P L E S ) i GROUP 2: A H HORIZOtl ( 7 S A M P L E S ) : GROUP 3 : A t HORIZON (2 S A M P L E S ) : GROUP 1 : B M HORIZON ( 1 S A M P L E ) ; P R O U P 5 : B F HORIZON (1 S A M P L E S ) ; GROUP 6: Bn HORIZON (8 S A M P L E S ) . GROUP 7 : Be HORIZON (1 S A M P L E ) ; GROUP 8 i C HORIZON <5 S A M P L E S ) / 6R0UP 9i NORTH ANOMALY STREAM SEDIMENTS ( E S A M P L E S ) ; G I M O P 1 0 ; STREAM SEDIMENTS AROUND RAP.CINS OF CAPOOSE L A K E (6 S A M P L E S ) . > S O I L S A M P L E S ; I STREAM SEDIMENT S A M P L E S ; • NOT D E T E C T E D . P E R C E N T E X T R A C T I O N I S C O M P A R E D T O A S E P A R A T E ' T O T A L ' D E T E R M I N A T I O N | S Y M B O L A N D B A R I N D I C A T E A V E R A G E P E R C E N T E X T R A C T I O N ( C E N T E R O F S Y M B O L ) A N D R A N G E O F P E R C E N T E X T R A C T I O N V A L U E S F I G U R E 1 4 : S E Q U E N T I A L E X T R A C T I O N O F C U , Z N , F E , M N , A N D M O F R O M S E L E C T E D S T R E A M S E D I M E N T A N D S O I L S A M P L E S , N O R T H A N O M A L Y A N D C A P O O S E L A K E A R E A , N E C H A K O P L A T E A U , B , C , 100 t ce S 60 ai £ 20H . 0 100 80 H s 5 <_> seo S B •*-* fe«o 0 100 t; = geo o ice D i S CO P *20-| 0 100 LtJ S 60 C Q 2 i - S 10 === s "20-1 0 CROUP RUHBER III ...... A . . . . . . A ul. i i i -* • i V . . . . * • T "ft I' •tl, 100 I 50 10 500 100 50 5 = 1 0.5 0.1 1000 1 500 ( UJ §1K> S 50 e io ^, 1 5 5 7 1 3 5 7 1 3 5 7 1 3 5 7 1 3 5 7 1 3 5 7 1 3 5 71 5 7 SODItM ACIDIFIED HYCSOXYtASI.W ACID DITHIONITE IVEFCvEN HYPOCHLORITE DISTILLED H'CSOCHLORIDE AMH0IIIUN FERCXILE HATER OXALATE 6R0UP 1: l-H H0RIZ0II (2 SAMPLES); CROUP 2: AM HORIZON <1 SAMPLES); GROUP 6R0UP 4: Bf HORIZON (3 SAMPLES); GROUP 5: BM HORIZON (0 SAKPIES); FR0UP 6R0UP 7l STREAM SEDIMENTS (7 SAMPLES). N I T R I C -P E K C i l L M I C A C I D S N I T R I C -P E R C H L O R I C "TOTAL* 3: EH H'.SIZON (2 SAMPLES) ; 6: C H02IZ0N (5 SAMPLES) ; > SOIL SAMPLES; l STREAM SEDIMENT S A M P L E S ; • NOT D E T E C T E D . P E R C E N T E X T R A C T I O N I S C O M P A R E D T O A S E P A R A T E ' T O T A L ' D E T E R M I N A T I O N S Y M B O L A N D BAR I N D I C A T E A V E R A G E " P E R C E N T E X T R A C T I O N ( C E N T E R O F S Y M B O L ) A N D R A N G E O F P E R C E N T E X T R A C T I O N V A L U E S F I G U R E 1 5 : S E Q U E N T I A L E X T R A C T I O N O F C U , Z N , F E , M N , A N D MO F R O M S E L E C T E D S T R E A M S E D I M E N T A N D S O I L S A M P L E S , G R E E N L A K E A R E A , N E C H A K O P L A T E A U , B . C . 93 100 -I e= 5 60 100 ; g 8 0 5 —— U J N J £ 4 0 £j 20 100 § 8 0 G 2 60 § S —• tuo 1 * 2 0 0 100 s 80 UJ 2 £ g 60 g S UJ ' 2 0 100 : 60 £ 40 20 ( R O U P • S - I * '"I IX 1 » 1 0 0 £ 5 0 ILJ S 1 0 5 (Vt i I o.s 0.1 0.05 J , . 1 0 0 0 5 0 0 § ioo I 5 0 •I. 100 50 . . .1 . . 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 9 I t 1 3 5 7 9 SOD I UK HYPOCHLORITE A C I D I F I E D D I S T I L L E D WATER HYDROXYLAMINE HYDROCHLORIDE A C I D AMMONIUM OXAUTE D I T H I O N I T E HYDROGEN PEROXIDE NITRIC -PERCHLORIC A C I D S NITRIC -PERCHLORIC •TOTAL" CROUP Is L - H HORIZON ( 5 S A M P L E S ) : GROUP 2 : AH H O R I Z O N (1 S A M P L E S ) ) GROUP 3 : AE HORIZON (1 S A M P L E ) ; GROUP 4: B H HORIZON ( 2 S A M P L E S ) . CROUP 5. Bf HORIZON ( 5 S A M P L E S ) . GROUP G: Br H O R I Z O N ( 1 S A M P L E ) , GROUP 7 . b HORIZON ( 1 2 S A . V L E S ) ; GROUP 8: BC HORIZON ( 1 S A M P L E ) : CROUP 9 : C HORIZON ( 7 S A M P L E S ) : GROUP 1 0 : S T R E A M S E D I M E N T S ( 4 S A M P L E S ) . _ • SOIL S A M P L E S : • STREAM SEDIMENT S A M P L E S : • NOT D E T E C T E D . P E R C E N T E X T R A C T I O N I S C O M P A R E D T O A S E P A R A T E ' T O T A L . ' D E T E R M I N A T I O N S Y M B O L A N D BAR I N D I C A T E A V E R A G E P E R C E N T E X T R A C T I O N ( C E N T E R O F ' S Y M B O L ) A N D R A N G E O F P E R C E N T E X T R A C T I O N V A L U E S F I G U R E 1 6 : S E Q U E N T I A L E X T R A C T I O N O F C U , Z N , F E , M N , A N D MO F R O M S E L E C T E D S T R E A M S E D I M E N T A N D S O I L S A M P L E S , F L S H A N D P O R T N O Y L A K E A R E A , N E C H A K O P L A T E A U , B . C , 9 4 Table XVI Percent^extraction of Cu, Zn, Fe, Hn and Ho from the organic f r a c t i o n of s o i l s , stream sediments and lake sediments, Capoose Lake, and Fish and Portnoy Lake areas Study Area Eleaent L-H Ef Ba C ss* D2 B* Capoose lake area Cu 69 0 0 0 22 16 21 13 Zn 61 0 0 0 0 0 8 5 re 15 0 0 0 0 0 1 16 Bn 64 0 0 0 4 3 13 0 Ho 93 15 21 49 7 24 26 16 Study Area Eleaent L-H Bf Ba c SS* B* Green Lake area Cu 71 0 1 3 30 16 21 13 Zn 52 0 0 0 0 0 8 5 Fe 24 b 0 0 0 0 1 16 Bn 71 0 0 0 10 3 13 0 Bo 80 20 14 12 26 24 26 16 Study Area Eleaent L-H Bf Ba C SS» F* p« F i s h and Ecrtncy Ca 60 6 7 1 5 80 Lake area Zn 28 0 0 0 2 36 62 Fe 17 0 0 0 0 32 13 Bn 14 0 0 0 1 66 72 flo 0 10 8 10 26 86 99 stream sediaents d e l t a i c sediaents, Capoose Lake nearshore sediaents, Capoose Lake basinal sediaents, Capoose Lake Fish Lake sediments Portnoy Lake sediaents * - determined following sodium hypochlorite extraction of minus 80 mesh fraction ss» -D* -H 3 -B* -F= -p» -9 5 T a b l e XVII Percent e x t r a c t i o n of Ca, Zn, Fe, Mn and Mo from the amorphous Fe oxide f r a c t i o n of s o i l s , s t r e a a sediments and l a k e sediments. Capoose Lake, and F i s h and Portnoy Lake a r e a s Stud; Area Eleaent L-B Bf Ba C SS» B* Capoose Lake area Cu 8 24 28 20 38 46 41 45 Zn 9 10 12 8 6 30 33 31 -' Fe 40 30 28 32 34 38 35 21 Hn 5 4 6 5 43 14 15 17 Ho 3 42 60 42 62 52 52 25 Study Area Eleaent L-H Ef Ba C SS» D 2 B* Green Lake area Ca 19 16 20 18 36 46 41 45 Zn 18 6 12 8 15 30 33 31 Fe 37 31 32 22 21 38 35 21 Bn 6 6 4 11 12 14 15 17 Bo 45 21 21 39 40 52 52 25 Study Area Eleaent L-H Bf Ba c SS* F* p» Fish and Portnoy Co 10 25 24 35 37 6 6 Lake area Zn 13 8 12 24 22 12 5 Fe 22 22 18 23 34 24 44 Bn 5 4 9 10 23 6 2 Bo 8 20 25 36 46 4 2 SS» - streaa sediaents D2 - deltaic sediaents, Capoose Lake H 3 - nearshore sediaents, Capoose Lake B* - basinal sediaents, Capoose Lake F 5 - Fish Lake sediments P* - Portnoy Lake sediaents * - determined following acid ammonium oxalate extraction, step 4 of sequential extraction procedure, Figure 12, page 61 96 Table XVIII Percent extraction of Cu, Zn, Fe, Mn and Mo from the s i l i c a t e residue f r a c t i o n of s o i l s , streaa sediments and lake sediments, Capoose Lake, and F i s h and Portnoy Lake areas Study Area Eleaent L-H Bf Ba C SS* H 3 B* Capoose lake area Ca 18 51 44 60 24 23 " 21 31 Zn 21 83 82 89 74 65 55 49 Fe 30 55 62 61 56 42 46 38 Bn 18 90 86 89 46 44 36 10 Ho 0 1 0 0 0 0 0 3 Study Area Eleaent L-H Bf Ea C SS* H 3 B* Green lake area Cu 9 41 44 24 26 23 21 31 Zn 22 92 87 75 74 65 55 49 Fe 22 43 45 49 48 42 46 •38 Hn 12 81 76 74 28 44 36 10 Ho 1 1 1 1 1 0 0 3 Study Area Eleaent L-H Bf Ba C SS* FS p6 F i s h and Fcrtnoy Ca 9 40 35 46 35 3 0 Lake area Zn 45 92 88 91 78 46 0 Fe 37 37 33 41 54 23 11 Bn 64 81 87 76 55 6 0 Ho 0 0 0 0 2 0 0 SS* - streaa sediaents Dz - d e l t a i c sediments, Capoose Lake H 3 - nearshore sediments, Capoose Lake B* - hasinal sediaents, Capoose Lake F s - Fish Lake sediments pa - Portnoy Lake sediments * - determined following n i t r i c / p e r c h l o r i c acid digestion f i n a l step of the sequential extraction procedure, Figure 12, page 61. 97 average of 5 to 35% of the respective • t o t a l " metal contents i n each area, whereas Fe accounts for 20 to 3558 of the ' t o t a l " Fe content* By contrast, only 4 to 11% of the " t o t a l " Hn content i s associated with amorphous Fe oxides, Acid ammonium oxalate extraction of Cu and Zn i s r e l a t i v e l y uniform from area to area. However association of these elements with c r y s t a l l i n e Fe oxides i s more variable. Cu and Fe concentrations each comprise an average of 35% of the " t o t a l " metal content at Green lake {Fig 15). although extraction of Fe from Fish and Portnoy Lake s o i l s i s s i m i l a r to that at Green Lake (Fig 16), Cu contents i n the l a t t e r area are 50% lower. At Capoose Lake (Fig 14), Cu comprises a s i m i l a r percentage of the ' t o t a l " content as at Fish and Portnoy Lakes, but Fe extraction i s 50% lower. S i m i l a r l y , s o l u b i l i t y of Ho depends on area examined. Hear Capoose Lake, most of the Ho i s released by solution of amorphous Fe oxides, whereas near Green Lake, most of the Ho i s l i b e r a t e d on solution of c r y s t a l l i n e Fe oxides. Near Fish and Portnoy Lakes, both Fe oxide f r a c t i o n s appear of equal importance. Relative amount of Zn, Fe, and Hn held i n s i l i c a t e . m i n e r a l s exceeds proportion of these elements held i n other f r a c t i o n s (Table XVIII). The s i l i c a t e residue contains, on the average, 75 to 90% of the " t o t a l " Zn and Mn, and 35 to 60% of the " t o t a l ' Fe. Cu contents, accounting for 25 to 60% of the " t o t a l " , exhibit greater v a r i a b i l i t y between and within sample groupings than i s associated with Cu extraction from other f r a c t i o n s . Cu content of s i l i c a t e minerals increases with increasing l e v e l s of " t o t a l " metal once the " t o t a l " value exceeds 100 ppm. 98 Consequently most of the Cu anomalies i n the 3 study areas appear to have a syngenetic o r i g i n . By contrast, low values of Mo i n the s i l i c a t e residue are c h a r a c t e r i s t i c . Because most of the Bo i s associated with various Fe oxide'fractions and the • t o t a l " Mo content of most samples i n each area i s low. Mo anomalies probably have an epigenetic o r i g i n . 3. Stream sediments Sequential extraction of Cu and Mo from stream sediments i s more variable than i n s o i l s (Figs 14 to 16). Although organic matter determinations are unavailable, increased v a r i a b i l i t y appears to r e f l e c t v i s i b l e fluctuations i n organic matter content. However hypochlorite dissolves only an average of 5 to 30% of the Cu and Ho (Table XVI), and i s even less e f f e c t i v e i n disso l v i n g Zn, Fe, and Hn. By contrast; Cu, Zn, Ho, and Hn appear associated with amorphous Hn and/or Fe oxides (Table XVII). Association of these elements with the amorphous Hn and/or Fe oxide f r a c t i o n i s greater than corresponding associations i n s o i l s , despite the fact that Fe content of amorphous oxide phases i n stream sediments i s similar to or l e s s than corresponding concentrations i n s o i l s . The s i l i c a t e residue i s r e l a t i v e l y impoverished i n Cu,'Zn, Ho, and Hn compared to nearby s o i l s , whereas Fe content of the f i n a l residue i s s i m i l a r to or greater than adjoining s o i l s . 4. Lake sediments Release of Cu, Zn, Fe, Mn, and Ho from Capoose Lake sediment d i f f e r s s u b s t a n t i a l l y from release of these elements 99 s • *» 0 1 ( 0 o in ss> ; c B *20 0 10 Tl ^ J I . .4i. * ». ,U>. 1 . . . W .«J* 11 «,' * " H,|rli lot I 50 I 11) J JLS_ I. I. yn* i 1 H to P • 1 Hlt>,t..t»* loom £ son a |ica> § an iw UJ I U g2 20-i - * * i • «... ••••t i -i » A* g 1 0 i s I i * l ' ^ • I ' l l 4 B 1 1 1 ! M U 3 S 7 9 11 SC0IL1 NtPOCHlOmlE ACIDlf U S irmftoxriMiix HKNOCHUMIDE ACID AfJTOIWI 0XALAIE o n u l w i l E unmoral KHIXIK nine - rcHiuiic ACIDS •lime - miiuu •T01M.' fPscPli CAPOOSE ua. lint "f. aimui ( 7 S A I T U S ) . CROUP ii CAPOOSE I A K C . uit v. CEMRAL <« S A H P U S J I H O U M I CAKIOSC LADT. line annul »swusii tmr 1 , CAPOOSE L A K E . H I E 'K'. B l l l l l 16 SAntESIl CROUP 5 , CAPOOSE LAKE. H U E ' C . ttASSMlE H SAItPlESli C O U P C, CATOOSE L A I I . IIDC ' C . nEARSlBAl ( « SAmiSli C R O U P ; : oreost L A K E . U X •»• . IIEAASIIORE ( « S A I W I S I I CROUP > : CAPOOSE LAKE , H U E T . REARSHORE 16 svmsii CAOUP 9 , CAPOOSE L A M . L I KE T . nation C J svms)i CROUP 1 0 : CAFSCSE LATE . L U E ' I ' . DELIA ( I SAKUSli CROUP 1 1 . FISH E A R S E O I K N T it SAH>US>> 6JMUP 121 PORIIOT LAKE SEDIfOI I S SAWIES). • ajmwiM COUECTCD wt S E D I H I I I S A M E S . CAPOOSE LAKE . . H A H S I M LAKE STDWEIII S A H P U S . CAPOOSE L A I I , . DELTAIC S E D I K H I S . CAPOOSE LAKE. . F I S H AHD posim LACE saiirim. P E R C E N T E X T R A C T I O N I S C O M P A R E D S Y M B O L A N D B A R I N D I C A T E A V E R A G E T O A S E P A R A T E ' T O T A L ' P E R C E N T E X T R A C T I O N ( C E N T E R O F D E T E R M I N A T I O N ' S Y M B O L ) A N D R A N G E O F P E R C E N T E X T R A C T I O N V A L U E S F I G U R E 1 7 : S E Q U E N T I A L E X T R A C T I O N O F C U , Z N , F E , M N , A N D MO F R O M S E L E C T E D L A K E S E D I M E N T S A M P L E S , C A P O O S E , F L S H A N D PORTNOY L A K E S , N E C H A K O P L A T E A U , B , C . 100 from Fish and Portnoy Lake sediments. Consequently the two areas are considered separately. Large fluctuations characterize extractions from nearshore samples (groups 5 to 9, Fi g 17) r e l a t i v e to more c e n t r a l l y collected samples (groups 1 to 1) of Capoose Lake. Though organic matter comprises 8 to 9% of the sediment (dry weight basis) near the middle of the lake, an average which i s s l i g h t l y higher than organic matter contents of nearshore sediments, the l a t t e r contain higher contents of hypochlorite soluble Cu, Zn, and Ho (Table XVI). . Extraction of trace elements from Capoose Lake sediment i s s i m i l a r to that from stream sediments (Figs 14 to 17). However amorphous Fe and Hn oxides are more e f f i c i e n t accumulators of Cu and Zn than are corresponding stream sediment fractions (Table XVII). Thus near the middle of the lake, 40 to 50% of the • t o t a l * Cu, 25 to 35% of the Zn, and 25 to 35% of the Mo are associated with acid ammonium oxalate soluble phases (Fig 17). Only 25% of the • t o t a l ' Fe content i s simultaneously dissolved whereas an average of 40 to 50% of the Fe i s s o l u b i l i z e d by d i t h i o n i t e . However c r y s t a l l i n e Fe oxides contain only 10% of the • t o t a l " Cu (Zn data unavailable), whereas they r e t a i n 50 to 70% of the Ho. Trace element extraction from nearshore samples i s s i m i l a r to that from basinal sediments f o r Cu, Zn, and Hn (Table XVII).. However Tamo's reagent dissolves an average of 35% of the Fe, and 50% of the Ho from nearshore samples at the expense of d i t h i o n i t e extraction l e v e l s . Although an average of only 17% of the Mn dissolves i n acid ammonium oxalate, t h i s represents a much greater f r a c t i o n of the •total^-Mn than i s extracted from nearby s o i l s (Table XVII). In 101 addition, an even more soluble Hn compound i s indicated as an important source of the element by enhanced e f f i c i e n c i e s of hydroxylamine hydrochloride and a c i d i f i e d d i s t i l l e d water extractions (Fig 17). An average of 5 to 10% of the ' t o t a l ' Zn content, and 1 to 8% of the ' t o t a l ' Cu content, also are li b e r a t e d by these reagents. Accompanying increases i n the proportion of weakly bound metal are decreases i n the f r a c t i o n of metal held within s i l i c a t e residues. For Mn, only 5 to 15% of the ' t o t a l ' of basinal sediments i s associated with the f i n a l residue. However content of Mn i n the s i l i c a t e residue of nearshore sediments ranges between 30 and 50% of the ' t o t a l ' , percentages which are si m i l a r to those of Cu, Zn and Fe i n basinal and nearshore samples (Fig 17). By contrast to the control of amorphous Fe oxides on trace element lev e l s i n Capoose Lake, organic matter content i n Fish (average 35%) and Portnoy (45%) Lakes (Chapter 6, Figs 65 and 69) appears to be a more important factor. Hypochlorite dissolves almost a l l of the Cu, Ho, and Mn, 35 to 60% of the Zn, and 15 to 35% of the Fe from samples from both lakes (Fig 17). Despite s i m i l a r appearance of sediment, hypochlorite dissolves approximately 35% of the Fe and Zn from Fish Lake sediment, and 15% and 60% of these elements, respectively, from Portnoy Lake sediment. In addition, s i g n i f i c a n t guantities of Zn are released by a c i d i f i e d d i s t i l l e d water only from Portnoy Lake sediment. Though Fish and Portnoy Lakes are subject to long periods of reducing conditions, 25 to 45% of the Fe i s i n the form of amorphous Fe oxides (Table XVII). Despite abundance of t h i s f r a c t i o n , l e s s than 6% of the ' t o t a l ' Cu, Zn, and Ho 102 content are simultaneously dissolved by Tamm's reagent. S i m i l a r l y , l e s s than 10% of the •total« Cu, Zn (Portnoy Lake only). Mo, and Hn concentrations of both lakes i s associated with the s i l i c a t e residue (table XVIII). However Fe and Zn comprise 25 and 45% of the • t o t a l 1 contents, respectively, i n the f i n a l residue of Fish Lake sediment. D. Discussion Solution of Cu, Zn, Ho, Fe, and Hn by various sequential extraction reagents, when considered as a series r e f l e c t i n g association of these elements with s p e c i f i c sample f r a c t i o n s , supports many of the assumptions made prior to the experiment. F a i l u r e of a c i d i f i e d d i s t i l l e d Hater and hydroxylamine hydrochloride to extract more than minor amounts of Cu, Zn, Ho, and Fe, and i n some instances Hn, suggests p r e c i p i t a t i o n of basic metal hydroxides during hypochlorite extraction i s not s i g n i f i c a n t i n the present study. In part, t h i s may be due to the fact that hypochlorite cannot completely oxidize organic matter, as indicated by the brown to black colouration of hypochlorite leachates. Consequently, organic matter complexing probably prevents p r e c i p i t a t i o n of basic metal hydroxides under alk a l i n e conditions of the extraction. Strength of complexing by released organic matter i s s t r i k i n g l y i l l u s t r a t e d i n a Cu-rich bog sample c o l l e c t e d near Bhipsaw Creek, B r i t i s h Columbia (personal comm, Lett, 1976), for which 77% of the 2.6% •total'^Cu i s extracted by hypochlorite. In contrast, a sulphide-rich bedrock sample containing 1.4% Cu and no organic matter was found to release only 500 ppm Cu 103 following hypochlorite treatment, a further 10,000 ppm metal being released by a c i d i f i e d d i s t i l l e d water. This confirms that hypochlorite w i l l oxidize sulphide minerals. However i n the absence of organic matter, Cu precipitates i n a form which i s redissolved under a c i d i c conditions. In the study areas of t h i s t h e s i s , only an occasional sample releases s i g n i f i c a n t concentrations of trace elements, p a r t i c u l a r l y Zn (as much as 43% of the • t o t a l * ) , on treatment by a c i d i f i e d d i s t i l l e d water. In view of the low * t o t a l * concentrations of Cu and Zn associated with these samples, enhanced extraction probably r e f l e c t s metals associated with carbonate minerals or cation exchange s i t e s . Hypochlorite i s an e f f i c i e n t agent f o r dissolving trace elements i n organic-rich samples. However factors besides absolute organic-matter concentrations are also s i g n i f i c a n t . This can be i l l u s t r a t e d by the comparison of two s i m i l a r l y appearing lake sediment samples taken near the middle of Capoose lake. Samples 169 and 181 (for l o c a t i o n ; see Fig 23) contain 8*9% and 7.9% organic matter contents, respectively. In the l a t t e r ; 36 ppm (56% of the ••total*) Cu i s dissolved compared to 7 ppm (5%) i n the former. This difference must r e f l e c t some physical or chemical property of organic matter comprising each sample. Organic matter near the middle of the lake i s f i n e l y divided, and i t s o r i g i n cannot be recognized by the unaided eye. Despite having a much larger surface area than the p a r t i a l l y decomposed twigs, leaves and conifer needles nearshore, organic matter i s r e l a t i v e l y unimportant i n accumulating trace elements 104 near the middle of the lake whereas an average of up to 45% of the ' t o t a l ' metal content of nearshore samples i s dissolved by hypochlorite (Fig 17). This suggests organic matter near the centre of the lake i s not suited f o r trace element scavenging. A l t e r n a t i v e l y , amorphous Fe and tin oxides or other sediment fractio n s p r e f e r e n t i a l l y extract metals from lake water compared to organic matter. Organic matter scavenging appears r e l a t i v e l y minor i n Capoose Lake. Nevertheless f a i l u r e to remove organic material prior to p a r t i a l extraction experiments may present problems., Comparison of acid ammonium oxalate extraction of Cu, Zn, Fe, Hn, and Ho by the sequential versus the simple extraction procedure indicates the l a t t e r commonly dissolves greater quantities of Cu; Zn, Fe, and Hn (Fig 18) . Magnitude of the difference i s p a r t i c u l a r l y s t r i k i n g f or Zn. Moreover, even i f a summation of metal contents dissolved by the f i r s t 4 steps of the sequential attack i s considered (Fig 19), values are not s u f f i c e n t l y high to equal the p a r t i a l extraction value, with the exception of Cu i n some samples. In contrast, sequential extraction of Mo greatly exceeds p a r t i a l extraction values. Such differences presumably r e l a t e to chemical properties organic matter, carbonate minerals, or amorphous Mn oxides which are p a r t i a l l y or completely dissolved by the f i r s t 3 steps of the sequential extraction. Because the sequential attack dissolves l e s s Cu and Zn, and the p a r t i a l extraction releases soluble forms of organic matter, enhanced extraction of the l a t t e r i s probably a consequence of f a i l i n g to eliminate organic matter prior to the experiment. 1 0 5 100 = 80 2 E0 U J 10 - 20 0 100 s 80 1 |eo U J Is 10 cr: U J " 20 0 100 g 80 | 60 U J I 10 CC U J a. 20 0 GROUP NUMBER MOLYBDEN-UM GROUP NUMEER_ 3 1 6 7 8 9 GROUP 1: DELTAIC SEDIMENTS. CAPCOSE LAKE 0. SAMPLES); GROUP 2: NEARSHORE SEDIMENTS. CAPOOSE LAKE (2 SAMPLES); GROUP 3: EASTERN BASIN SEDIMENTS. CAPOOSE LAII (5 SAMPLES); GROUP 1: WESTERN BASIN SEDIMENTS, CAPOOSE LAKE (5 SAMPLES); GROUP 5: BAXTER LAKE SEDIMENTS (3 SAMPLES); GROUP 6: CANOE LAKE SEDIMENTS (3 SAMPLES); GROUP 7: FISH LAKE SEDIMENTS (1 SAMPLE); GROUP 3: VERONICA LAKE SEDIMENTS (1 SAMPLE); t B « a i g -GROUP 9: WASKETT LAKE SEDIMENTS (1 SAMPLE). 1 2 3 1 5 6 7 8 9 • PERCENTAGE EXTRACTION OF THE SUM OF THE FIRST '1 SEOUEHTIAL EXTRACTIONS. • PERCENTAGE EXTRACTION OF THE SIMPLE ACID AMMONIUM OXALATE PARTIAL EXTRACTION. P E R C E N T E X T R A C T I O N I S C O M P A R E D T O A S E P A R A T E ' T O T A L * D E T E R M I N A T I O N S Y M B O L A N D B A R I N D I C A T E A V E R A G E P E R C E N T E X T R A C T I O N ( C E N T E R O F S Y M B O L ) A N D R A N G E O F P E R C E N T E X T R A C T I O N V A L U E S F I G U R E 1 8 : C O M P A R I S O N O F S E Q U E N T I A L A N D S I M P L E P A R T I A L E X T R A C T I O N O F C u , Z N , F E , M N , A N D MO ( P E R C E N T E X T R A C T I O N ) F R O M S E L E C T E D L A K E S E D I M E N T S A M P L E S , N E C H A K O P L A T E A U , B . C . E 1 0 0 ° - 5 0 I Q . S 5 1 5 C 0 o_ 1 0 0 ' 5 0 0 . 1 1 0 0 0 5 0 0 I C O 1 0 0 5 0 2 1 0 U J 5 C O il 4 I A t 3 S C T 2 <l U X 0 a T L T A I C S E D S . ICAPOOSE L;.\E -•4-± i i + t 3 S C T 2 1 U X 0 r T KF: :SE LAKE 71 ft 3 S C 7 2 1 U X 0 1 T ASTEF.'. HAS!.'.' ZAPOOSi L f t k ; 1 1 3 S C 2 1 U X ESTESi; asm CAPCKE _AKE A L L A AmtL 3 S C T 2 1 U X 0 K T 1 3 S C T 2 1 U X 0 It T BAXTER LAKE I CAIIOt LAKE SEDIKEJ'TS ISEDI'E'ITS • • 1 3 S C T 2 - U X 0 n T rISH _ K E I I I > 1 5 S C T 2 4 U X 0 M T • © i X S . ' M C ; LAKE :EI:::EN"S 1 5 S C I 411 X 0 .1 T .;.v.ETT LAKE sETlMMS . E X T M C T i e . 1 1 : . S O M E ! K Y P C E i l X K I T E : D T M C T i O . ' l 2 : A C i . i F I E . D I S T I L L E D WATER; B C T E A C t K M 3 : K'i " O X y L A m . \ E H Y : S 0 C K L O S I D E ; EXTRACTION 1 : A C I D A V 0 . N I U 1 OXALATE: EXTRACT I C l i S U H : SU.V.ATIO.I OF D E T E R M I N A T I O N S F R C 1 THE F I R S T <l E X T S A C T I O I S i E X T R A C T I O S a-. S I K P L I A C I D A l W M I l l f l OXALATE P A R T I A L EXTRACT'.OH/ E X T R A C T I O N T O T : N I T R I C / P E R C W L C S i C A C I D ' T O T A L * D E T E i a ' . ' H T i a H • T R A C E E L E M E N T C O N T E N T I N S E Q U E N T I A L E X T R A C T I O N S 1 T O 4 • S U M O F S E Q U E N T I A L E X T R A C T I O N S 1 T O 4 A S I M P L E A C I D AMMONIUM O X A L A T E P A R T I A L E X T R A C T I O N S N I T R I C / P E R C H L O R I C A C I D ' T O T A L ' D E T E R M I N A T I O N • N O T D E T E C T E D I S Y M B O L A N D B A R I N D I C A T E A V E R A G E P E R C E N T E X T R A C T I O N ( C E N T E R O F 7 S Y M B O L ) A N D R A N G E O F P E R C E N T E X T R A C T I O N V A L U E S F I G U R E 1 9 : C O M P A R I S O N O F S E Q U E N T I A L A N D S I M P L E P A R T I A L E X T R A C T I O N O F C u , Z N , F E , M N , A N D MO ( P P M ) F R O M S E L E C T E D L A K E S E D I M E N T S A M P L E S , N E C H A K O P L A T E A U , B . C . 107 The necessity to redissolve metal sulphide prec i p i t a t e s following d i t h i o n i t e treatment i s confirmed by enhanced Cu le v e l s (Zn data unavailable) i n hydrogen peroxide extracts. Though d i t h i o n i t e does not precipitate Mo sulphides, some samples release s i g n i f i c a n t quantities of Mo on application of hydrogen peroxide. A sample from Capoose Lake, containing 100 ppm Mo, releases 77 ppm on addition of hydrogen peroxide. This compares to 10 ppm and 11 ppm s c l u b i l i z e d by application of di t h i o n i t e and oxalate, respectively. Because Ho i s l i b e r a t e d mainly by d i t h i o n i t e , enhanced l e v e l s of the element i n hydrogen peroxide extracts are probably caused by p e c u l i a r i t i e s of i n d i v i d u a l samples. The concluding n i t r i c / p e r c h l o r i c acid attack extracts metals associated with s i l i c a t e minerals. Variation i n Cu content from 13% to 8935 i n *Bm» s o i l samples near Capoose Lake indicates that the s i l i c a t e component may control o v e r a l l d i s t r i b u t i o n s i n some cases, whereas i n others i t i s r e l a t i v e l y unimportant. For example, 2 s o i l samples l y i n g in s i m i l a r seepage environments and containing s i m i l a r Cu contents, can be associated with widely d i f f e r e n t mechanisms of metal enrichment. Both samples are from the *Ah' horizon, and contain approximately 500 ppm Cu. Sample 567 (Fig 23) retains 64% of i t s • t o t a l * (333 ppm) u n t i l the f i n a l extraction whereas by comparison* sample 303 only releases 15% (98 ppm). Conseguently, a syngenetic o r i g i n i s indicated for the f i r s t anomaly whereas an epigenetic genesis i s suggested for the second. Despite problems attributable to the chemistry of sample 108 f r a c t i o n s , generalizations can be made describing extraction trends. For example, hypochlorite commonly dissolves s i g n i f i c a n t amounts of trace elements from samples containing appreciable quantities of organic matter. However i n some marine environments, organic matter does not appear to scavenge trace elements (Gupta and Chen, 1975). In the present study, hypochlorite extractions are able to distinguish between hydromorphic and mechanical ori g i n s for metal-rich zones, although the p o s s i b i l i t y e x i s t s that an i n f e r r e d hydromorphic anomaly may also r e f l e c t an abundance of primary sulphide minerals. S i m i l a r l y , enhanced l e v e l s of Cu, Zn, and Mo associated with amorphous Fe oxides, or enhanced contents of Mo associated with c r y s t a l l i n e Fe oxides, i s i n d i c a t i v e of an epigenetic anomaly. Importance of residue-bound metal decreases following the sequence: s o i l s , stream sediments, lake sediments (Table XVIII; Figs 20 and 21). In the Capoose Lake area, the sequence i s i l l u s t r a t e d by Mn data. Besldue-Mn accounts f o r 75 to 90% of the • t o t a l 1 metal content i n s o i l s whereas t h i s f r a c t i o n accounts for only 25 to 55% i n stream sediments, depending on area examined. Proportion of residue-Mn i n nearshore or d e l t a i c sediments i s s i m i l a r to stream sediments. However the percentage of Hn associated with the s i l i c a t e residue diminishes to between 5 and 15% of the • t o t a l * i n c e n t r a l l y - c o l l e c t e d Capoose Lake sediments. In an analogous fashion, f r a c t i o n of Zn held by s i l i c a t e minerals declines from 75 to 90% i n s o i l s to 49% i n basinal lake sediments. However Cu values decrease only s l i g h t l y , from the 25 to 60% range to the 20 to 30% range. 109 80 40 0 25 -o 80 40 0 80 u < en x 40 « 80 40 COPPER ZINC IRON M4J MANGANESE :LJU: z n u « w 0 P* 80 40 0 1 2 3 45. 6 1 2 3 45 6 1 2 3 45 6 1 2 3 45 6 1 2 3 4 56 1 2 3 45 6 1 2 3 45 6 EXTRACTION B L E G E N D EXTRACTIONS A. SODIUM HYPOCHLORITE B. ACIDIFIED DISTILLED WATER C. HYDROXYLAMINE HYDROCHLORIDE D. ACID AMMONIUM OXALATE E. DITHIONITE F. HYDROGEN PEROXIDE G. NITRIC - PERCHLORIC ACIDS GROUP NUMBER 1. ORGANIC-RICH SOIL HORIZONS 2. MINERAL-RICH SOIL HORIZONS 3. STREAM SEDIMENTS 4 . NEARSHORE SEDIMENTS, CAPOOSE L. 5. DELTAIC SEDIMENTS, CAPOOSE L. 6. BASINAL SEDIMENTS, CAPOOSE L. PERCENT EXTRACTION I S COMPARED TO A SEPARATE ' T O T A L / DETERMINATION BAR INDICATES RANGE OF PERCENT EXTRACTION V A L U E S F I G U R E 2 0 : COMPARISON O F T H E S E Q U E N T I A L E X T R A C T A B I L I T Y O F C U , Z N , F E , M N , AND MO FROM S O I L , STREAM SEDIMENT AND LAKE SEDIMENT S A M P L E S , CAPOOSE L A K E AREA 110 COPPER 52: o M E-" U < Pi H X W £-IZ W u w PL, '13 m\ B £ 9 Snff l" ™ n 1 2 345 1 2 345 1 2 345 1 2 345 1 2 345 1 2 345 1 2 345 NUMBER EXTRACTION A B C D E F 6 L E G E EXTRACTIONS A. SODIUM HYPOCHLORITE B . ACIDIFIED DISTILLED WATER C. HYDROXYLAMINE HYDROCHLORIDE D. ACID AMMONIUM OXALATE E. DITHIONITE F. HYDROGEN PEROXIDE G. NITRIC - PERCHLORIC ACIDS N D GROUP NUMBER 1. ORGANIC-RICH SOIL HORIZONS 2. MINERAL-RICH SOIL . HORIZONS 3. STREAM SEDIMENTS 4. FISH LAKE SEDIMENTS 5. PORTNOY LAKE SEDIM-ENTS PERCENT EXTRACTION IS COMPARED TO A SEPARATE ' T O T A L ' DETERMINATION BAR INDICATES RANGE OF PERCENT EXTRACTION VALUES FIGURE 20: COMPARISON OF T H E SEQUENTIAL EXTRACTABILITY OF Cu, Z N , F E , MN, AND MO FROM S O I L , STREAM SEDIMENT AND LAKE SEDIMENT SAMPLES, F L S H AND PORTNOY LAKE AREA 111 Fraction of Fe and Mo i n the f i n a l residue i s approximately constant regardless of sample environment. In the Fish and Portnoy Lake area, mechanics of trace element retention i n s o i l s and stream sediments are s i m i l a r to that near Capoose Lake. However within Fish and Portnoy Lakes, organic matter scavenging accounts for almost the ent i r e trace element content. Amorphous Fe oxides and other f r a c t i o n s which are important in Capoose Lake are r e l a t i v e l y i n s i g n i f i c a n t i n the two lakes. Consequently trace element retention i n s o i l and stream samples cannot be compared to lake sediment parameters, with the possible exception of •L-H* s o i l samples. Lake sediments contain a higher proportion of trace elements i n a hypochlorite soluble form than the 'L-H* horizon. However higher values i n lake sediments may r e f l e c t the d i f f i c u l t y of avoiding the d i l u t i n g influence of inorganic contaminants i n s o i l s . Enhanced s o l u b i l i t y of Cu, Zn, and Hn from lake sediments compared to s o i l s and stream sediments i s evident at both the Capoose Lake, and Fish* and Portnoy Lake areas (Tables XVI, XVII and XVIII). This tendency also corresponds to an enhancement i n weathered character of lake sediments compared to s o i l s . Despite the fa c t stream sediment i s the main source of Capoose lake sediment, association of trace elements with amorphous Fe and Hn oxides suggests metal deposition from groundwater i s the predominent mechanism by which trace elements accumulate i n Capoose Lake. , S i m i l a r l y , base metal anomalies i n Fish and Portnoy Lakes appear hydromorphically-derived and are associated with organic matter. 112 Proportion of amorphous Fe oxides does not change appreciably from s o i l s to streams to lakes near Capoose Lake. However content of trace elements associated with this f r a c t i o n increases s u b s t a n t i a l l y . Apparently amorphous Fe (or Hn) oxide phases are better scavenging agents i n streams and lakes than i n s o i l s . A l t e r n a t i v e l y i n f l u x of dissolved metals to stream and lake environments i s greater than to s o i l environments. The l a t t e r explanation appears probable in view of the well-drained and aerated nature of s o i l s compared to stream and lake beds. Moreover, a r e l a t i v e l y high proportion of read i l y soluble-Zn and other metals i n boggy or seepage zones indicates trace elements i n s o i l s are avai l a b l e f o r dispersion within groundwater to the l a t t e r two environments. Fe oxides comprise a r e l a t i v e l y minor f r a c t i o n of Fish and Portnoy lake sediments. Further, lake sediment composition d i f f e r s r a d i c a l l y from that of surrounding s o i l s and stream sediments. Consequently comparisons between parameters of trace element retention i n the catchment and the lake are not relevent. Nevertheless, increase i n trace element association with amorphous Fe sesguixodes i n seepage areas* and organic matter concentration of metals i n bogs near both lakes suggest groundwater dispersion to the lake i s an important fa c t o r . Despite v a r i a b i l i t y a t t r i b u t a b l e to sediment composition, and the fact that a large number of factors control trace element accumulation within lakes, genesis of lake sediment anomalies by hydromorphic processes appears r e l a t i v e l y important. However factors peculiar to i n d i v i d u a l lakes may greatly a f f e c t dispersion processes and anomaly genesis. A 113 number of these factors are considered i n the next chapter with reference to the Capoose Lake, and Fish and Portnoy Lake anomalies (Fig 3). 114 CHAPTER 6 ORIENTATION STUDIES AT CAPOOSE, AND FISH AND PORTNOY LAKES I DETAILED LAKE SEDIMENT SURVEYS A. Introduction Results of the-reconnaissance study suggest that despite v a r i a b i l i t y of limnological processes and despite differences i n mechanisms of trace metal i n f l u x into lakes, sediment data r e f l e c t a l l known mineral showings. However metal l e v e l s show considerable v a r i a b i l i t y within a lake (Table VII) . The p o s s i b l i t y of c o l l e c t i n g anomalous samples from background lakes or, conversely, observing background metal leve l s i n anomalous lakes cannot be excluded. For exploration purposes, i t i s therefore necessary to establish c r i t e r i a to d i s t i n g u i s h anomalies r e f l e c t i n g mineralized bedrock from anomalies related to other factors; This can be achieved best by detailed studies of factors influencing metal dispersion into and i n lakes. The Capoose Lake, and Fish and Portnoy Lake anomalies, r e f l e c t i n g base metal enrichment i n contrasting limnological environments, were selected for detailed studies. In both cases mineral showings and related geochemical anomalies occur i n the lake catchment; It was therefore possible to devise a sampling plan, based larg e l y on metal-rich zones outlined by Rio Tinto, to follow metal dispersion t r a i n s from t h e i r source, along streams and other pathways int o the lake. Once i n the lake, metal accumulation patterns were investigated by sampling lake sediments and waters. 115 E. Capoose Lake 1. Introduction Capoose Lake and several neighbouring lakes are associated with the most s t r i k i n g concentration of base metals uncovered by the reconnaissance survey (Pigs 5 to 9). Concentrations of up to 125 ppm Cu, 73 ppm Mo, 27 ppm Pb and 540 ppm Zn i n Capoose Lake greatly-exceed regional thresholds of 95 ppm Cu, 9 ppm Mo, 6 ppm Pb and 237 ppm Zn (Table I I ) . Two prominent zones of Cu and/or Ho mineral showings north and south of Capoose Lake are recognized (Fig 22) within the Capoose Lake watershed (Boyle and Troup, 1975), These are drained by Swannell and Bio Creeks ( u n o f f i c i a l names) i n the north and t r i b u t a r i e s of Capoose Creek i n the south. Numerous other small mineral occurrences and Cu -Ho geochemical anomalies also are known; A l l streams and springs discharging into Capoose Lake were sampled so that any metal-rich area i n proximity to the lake which might influence lake metal l e v e l s would be included (Fig 23). One such Ho-rich region, designated as the •South Zone t, l i e s adjacent to the southwest guarter of the lake. Studies also included Pb - Zn - Cu anomalies i n overburden at the eastern fringe of the catchment on Fawnie Nose south of Green Lake (Fig 24). This region, referred to as the Green Lake anomaly and drained by several t r i b u t a r i e s of Capoose Creek, i s marked by acid stream water, and enhanced Pb, Zn, Cu, Mo and Ag l e v e l s i n s o i l s and stream sediments. I t was hoped to trace dispersion of these elements from the mountains to Capoose Lake. 2. Description of the study area 1 1 6 1 , N O R T H A N O M A L Y C U - MO 2 , S O U T H Z O N E f ] 0 . 3 , S O U T H A N O M A L Y MO •4, W E S T A N O M A L Y C U - MO 5 . E A S T Z O N E M O 6 . G R E E N L A K E A N O M A L Y P B - Z N - C U - A G 7 . G R E E N L A K E A N O M A L Y C U - Z N - A G 8 . G R E E N L A K E A N O M A L Y C U - A G F I G U R E 2 2 : M I N E R A L O C C U R R E N C E S / A N D O F F I C I A L A N D U N O F F I C I A L L O C A L E N A M E S O F T H E C A P O O S E A N D G R E E N L A K E A R E A S 1 1 7 FIGURE 23: SAMPLE LOCATIONS AT CAPOOSE LAKE AND THE NORTH ANOMALY DESCRIBED IN TEXT ASOILS, "STREAM SEDIMENTS. ©LAKE SEDIMENTS, OLAKE CORES 1 1 8 FIGURE 24: SAMPLE LOCATIONS NEAR GREEN LAKE DESCRIBED IN TEXT A S O I L S , BSTREAM SEDIMENTS 119 a. Geology and mineralization The Capoose Lake area i s underlain by a large i n t r u s i v e batholith of granodiorite composition (Jurassic and/or Cretaceous age), surrounded to the north and west by volcanic and sedimentary strata of the Takla group volcanics (Fig 25). In the south, bedrock which i s concealed beneath up to 20 m of g l a c i a l deposits, i s probably volcanic (Boyle and Troup, 1975) and may include the Hazelton, Ootsa Lake or Endako groups as well as Takla volcanics (Tipper, 1961). At Capoose Lake, the intrusion has a r e l a t i v e l y uniform texture and exposures are massive, poorly fractured and medium to coarse grained. The pluton was intruded by guartz porphyry and diabase dikes and i n the northwest i s overlain by remnants of roof pendants. Contact relationships with Takla volcanic rocks are sharp, but are usually concealed by extensive g l a c i a l and c o l l u v i a l overburden. Volcanic bedrock i n immediate contact with the i n t r u s i o n i s metamorphosed to hornfels along a zone 150 to 300 m wide and cut by numerous veins (Nahring, 1971). Geology at Green Lake i s more complex than at Capoose. Green Lake ov e r l i e s the contact between a fine grained granodiorite and Takla volcanic rocks. The contact zone between Takla rocks and the i n t r u s i o n has been intruded, at a shallow angle to the volcanic s t r a t a , by a 300 m thick, pervasively p y r i t i z e d (up to 15% pyrite) and epidotized rhyodacite. Weathering of t h i s sulphide-rich unit has produced the most prominent gossan of the Nechako plateau (Tipper, 1963), and an associated pH anomaly (Boyle and Troup, 1975) where stream a c i d i t y i s commonly 4.0 or l e s s . Takla volcanic rocks l i e above 1 2 0 F I G U R E 2 5 : L O C A T I O N , G E O L O G Y A N D M I N E R A L I Z A T I O N , C A P O O S E L A K E G R A N O D I O R I T E , C E N T R A L B R I T I S H C O L U M B I A ( F R O M B O Y L E A N D T R O U P , 1 9 7 5 ) 121 the rhyodacite unit. They consist of a lower group of andesitic aingydaloidal and vesicular, aphanitic and porphyritic extrusive flows; and an upper group of r h y o l i t i c ash-flow t u f f , a i r - f a l l t u f f * water-lain a r g i l l i t e and minor flow breccia (Nahring, 1971) The study area was extensively glaciated during the Pleistocene with the l a s t major ice movement from the southwest. Predominance of g l a c i a l structures along t h i s d i r e c t i o n suggests most deposition occurred at t h i s time. Overburden i s comprised primarily of ground moraine on which l i e s numerous small eskers and drumlins. Thickness of overburden i s greatest i n the lowlands where depth to bedrock may exceed 20 m but thins towards the east, and i s mainly locally-derived talus or colluvium i n the mountains. Occurrences of Cu - Ho and Pb - Zn mineralized bedrock or metal-rich overburden are indicated on Figs 22 and 26 near Capoose Lake. Three major Cu - Ho mineral showings are known (Boyle and Troup, 1975) where traces of chalcopyrite and molybdenite are disseminated i n narrow zones along c l o s e l y -spaced fractures (Hewton and Harsh, 1970).. Most prominent of the mineralized areas, the *North Anomaly', l i e s 2500 m north of the lake. This region has been tested by an induced po l a r i z a t i o n (IP) survey and shallow blast p i t s . Grades approach 0.1% combined Cu and Ho. However overall size and average grade of the mineralized zone remains undefined and only a few of the many geochemical anomalies have been explained by i d e n t i f i c a t i o n of chalcopyrite or molybdenite occurrences. Other areas where base metal enrichment i n s o i l s l i e s near 122 the lake are indicated on Fig 26. Although not documented by findings of sulphide mineral showings, unusually high Cu and Mo l e v e l s i n overburden suggest the granodiorite probably contains chalcopyrite and molybdenite occurrences si m i l a r to those of the North Anomaly. IP surveys completed over these anomalies indicate bedrock does not contain sulphide concentrations exceeding those at the North Anomaly. Relationships between bedrock and overburden Cu and Mo anomalies southeast and south of Capoose Lake are not clear. Nevertheless anomalies are i n d i c a t i v e of abnormal concentrations of metals in the catchment which may influence trace metal content of the nearby lake. The South Zone occurrence along the lakeshore i s p a r t i c u l a r l y important because of i t s proximity to the lake. Takla volcanic rocks are associated with widespread Pb, Zn and/or Cu anomalies, and more l o c a l i z e d zones of Mo and Ag enrichment. Although traces of galena occur as str i n g e r s i n extrusive units and replace garnet i n sedimentary s t r a t a (Nahring, 1971), no major occurrences of Pb and/or Zn sulphides are recognized. Traces of Cu-bearing minerals are associated with the rhyodacite unit (personal comm, Troup, 1973). 1 b. Topographic setting and drainage Capoose Lake (elevation 1020 m) occupies part of a major 0-shaped valley crosscutting the axis of the Fawnie Range between Mount Swannell and T u t i a i Mountain (Fig 22). The valley i s underlain by extensive deposits of g l a c i o f l u v i a l sands and gravels which extend to 1140 m elevations. Slopes on the north side of the lake extend f a i r l y continuously from 1020 m to the 123 Hount Swannell summit at 1830 m whereas i n the south, topography f l a t t e n s abruptly at 1100 m. Geology and thickness of overburden underlying the lake are not known and recent sediment obscures i d e n t i f i c a t i o n of pre-lake parent material. However i n view of numerous granodiorite explosures i n the h i l l s near the lake, and small outcrops beside the lake i n the southwest, Capoose Lake i s probably underlain by the granodiorite pluton. The lake i s the centre of an extensive stream network, draining approximately 150 km2 (Fig 22). The largest stream, Capoose Creek* i s over 13 km long, measured from i t s source above t r e e l i n e (1690 m) near Fawnie Nose or Tu t i a i Mountain to i t s inflow bay at Capoose Lake. At point of entry, the stream i s 6 m wide and 0.8 m deep. Other major streams named u n o f f i c i a l l y * i n order of decreasing crossectional area, include Chatupa Creek which flows along the eastern extension of the Capoose Lake v a l l e y ; Asarco Creek draining the northwest guarter of T u t i a i Mountain; and Swannell Creek flowing over the southwest flank of Mount Swannell. Apart from these major channels, numerous small streams drain less than 1 km2 areas adjoining Capoose Lake. Topography along the upper reaches of Swannell and Capoose Creeks i s described further because these streams drain prominent base metal anomalies selected for detailed study. Swannell Creek, crossing several Cu - Mo anomalies over the North Anomaly, flows along a shallow valley (gradient 1 i n 7), 10 m deep, eroded into c o l l u v i a l deposits near the summit of Hount Swannell. At lower elevations, Swannell Creek i s more deeply incised (up to 20 m) i n g l a c i o f l u v i a l deposits. A second 124 major stream, Rio Creek, marks the easternmost boundary of the North Anomaly. Rio Creek flows down a much steeper slope than Swannell Creek (1 i n 3.5) and i s i n c i s e d i n a deeper v a l l e y . Overburden near i t s headwaters i s cclluvium. However within the confines of the North Anomaly, s u r f i c i a l deposits are comprised of g l a c i o f l u v i a l material s i m i l a r to those cut by Swannell Creek. Both streams are a c t i v e l y downcutting and have banks comprised of talus or c o l l u v i a l material. Swannell Creek enters Capoose Lake opposite Capoose Creek (Fig 22). Rio Creek does not enter the lake d i r e c t l y but joins Chatupa Creek several hundred meters upstream from Capoose Lake. Swannell and Rio Creeks constitute the backbone of the drainage network of the North Anomaly. ; Springs and seepages are numerous throughout the area and are p a r t i c u l a r l y abundant between Swannell and Rio Creeks, along the west bank of Swannell Creek, and near a prominent topographic i n f l e c t i o n and bench at 1140 m. Zones of groundwater emergence are normally associated with bogs and organic-rich s o i l s . T r i butaries of Capoose Creek near Green Lake, named u n o f f i c i a l l y from north to south as Pyrite, Capoose, Acid and Anomaly Creeks (Fig 22), drain 50 km2 on T u t i a i and Fawnie Nose Hountains, including numerous Pb - Zn - Cu and/or Ag anomalies. Streams can be divided into two groups on the basis of water pH. Pyrite and Acid Creeks drain gossans and are strongly a c i d i c (Fig 41) i Acidic pH also i s encountered occasionally i n seepage areas along Capoose Creek near the gossans. Acidic environments are associated with red-brown (7.5YR4/4) Fe oxide pr e c i p i t a t e s 125 which l o c a l l y cement streambed material. In these cases, the streambed also i s characterized by an i n a b i l i t y of mosses or grasses to root i n adjacent stream banks. By contrast, Capoose and Anomaly Creeks are more neutral {pH 6.0 to 6.5), as are the majority of seepages, and vegetation growth nearby i s not r e s t r i c t e d . Despite differences i n water a c i d i t y , topographic settings of both sets of streams are s i m i l a r . Gradients are steep (1 i n 3 or 4) and valleys are deeply incised 30 m into c o l l u v i a l or talus slopes. The •v* shape i s replaced by a wide, a l l u v i a l -f i l l e d and bog-overlain valley within 500 m of Capoose Creek. Capoose Creek proper "commences as the outflow of Green Lake and meanders across a wide valley between T u t i a i and Fawnie Hose Hountain underlain by r e l a t i v e l y thin and l o c a l l y derived overburden. Capoose Creek downcuts 15 m or more i n t o exotic s u r f i c i a l deposits to the west of the Fawnie Range; The creek also dissects granodiorite outcrop within 1 to 5 km of Capoose Lake. Seepages and springs emerge at closely-spaced i n t e r v a l s throughout the Green Lake area, p a r t i c u l a r l y along stream banks. Overburden i s usually water-saturated and bogs are a common feature between major streams near the alpine t r e e l i n e {1690 m). Above t r e e l i n e , springs and seepages are even more abundant. They are commonly associated with s o l i f l u c t i o n lobes, f r o s t b o i l s and polygonal ground. Huch of the water i s derived from melting of the active layer overlying permafrost. c. S o i l s and vegetation 126 Three major parent materials are recognized: extensive deposits of ground moraine i n low^lying areas west of the Fawnie flange, r e s i d u a l material of the mountains, and a t r a n s i t i o n a l zone between the two. Podzols and brunisols are most common on ground moraine, although gleysols and organic s o i l s are l o c a l l y important i n seepage areas. Begosols, and poorly-developed brunisols and l u v i s o l s characterize the mountain range where pedoturbation associated with freeze/thaw cycles, water-saturated overburden, and s o l i f l u c t i o n prevent extensive s o i l formation. These s o i l s have been considered r e s i d u a l (Boyle and Troup, 1975) i n the sense that they are r e l a t i v e l y unweathered and l i e close to t h e i r bedrock source, although there i s l i t t l e likelyhood in most-cases that they d i r e c t l y o verlie parent bedrock. The t r a n s i t i o n between mountain and lowland s o i l s i s an area of considerable mixing of overburden caused by downslope movement and groundwater emergence. S o i l s are mostly water-saturated gleysols, r i c h i n organic matter, or bogs. However podzols and brunisols also are encountered in d r i e r areas. Vegetation of lodgepole pine and black spruce are found throughout the Capoose lake area, with the l a t t e r confined primarily to stream channels and peripheries of bogs. A t r a n s i t i o n zone to stunted lodgepole pine and spruce occurs near the t r e e l i n e (1690 m) on mountain slopes.: At s t i l l higher elevations, climate i s too severe for tree growth, and grass, moss and lichens comprise the vegetation. d. Lake description Capoose Lake has a maximum length, width and depth of 3.3 127 km, 515 m and 30 m respectively, and i s elongated i n a northeast -southwest d i r e c t i o n , narrowing to 140 m near Capoose creek. This c o n s t r i c t i o n r e s u l t s from deposition of substantial quantities of sediment by Capoose and Swannell Creeks and divides the lake into two basins. Sediment from Chatupa and Asarco Creeks has produced a second prominent delta (Fig 23). Coarse c l a s t i c material also characterizes lake sediments within 20 m of the shore. In the southwest, bedrock d i s i n t e g r a t i n g by frost-heaving has contributed angular blocks of granodiorite which pave the lake f l o o r . Bogs are notably absent from lake margins, and grasses and reeds are r a r e l y encountered i n the nearshore environment. Large plants or roots are not observed i n sediment samples taken near the middle of the lake. Sediment can be divided into 3 major classes on the basis of physical properties and dis p o s i t i o n within the lake: nearshore e l a s t i c s , d e l t a i c e l a s t i c s and c e n t r a l basin oozes. The f i r s t two groups are composed of inorganic materials, although nearshore sediments contain a higher proportion of boulders. Organic matter i s present i n the form of r e l a t i v e l y undecomposed twigs, needles and leaves* and may account for up to 19% of the weight of a sediment sample. Such concentrations represent the highest organic matter l e v e l s i n Capoose Lake (Fig 36), though average contents of 5.4% are 60% lower than average contents of more f i n e l y - d i v i d e d oozes near the middle of the lake (Table XIX). Oozes of deeper parts of the lake have, to the unaided eye, a uniform appearance and, i n view of t h e i r usual o l i v e green colour, may be c l a s s i f i e d as gyttja (Timperley and A l l a n , 1974). Table XIX Trace metal content (ppm) of Capoose Lake nearshore, d e l t a , and central basin sediment Sample p o s i t i o n w i t h i n Capoose Lake O.M. % Cu ppm Zn ppm Mo ppm Fe % Mn ppm Pb ppm Temp °C pH Depth f e e t DFS f e e t # D e l t a Mean 3.4 43 138 3.3 2.0 4 20 14 0.0 6.7 32 133 9 Range 2.0- 3.6 29- 63 115-116 3.9- 7.6 1.7-2.3 290- 683 11-1T 3.9-10.1 6 .6 -6 .0 14-49 4C-270 E a s t e r n Mean 2.8 30 123 3.7 1.0 460 * 10.3 6 0 S 9 60 14 shore Range 1.7- 4.7 18- 31 81-106 1.7- 7.9 1.0-3.2 188-1130 3-11 9 .1-11. • 6.7-6.9 1-16 10-109 Western Mean 7.1 62 237 9.0 2.2 5S6 10 9.4 6.a 13 51 31 shore Range 3.7-13.6 33-117 123-434 3.6-22.0 1.3-3.4 255-1110 6-1S 7.9-10.9 6.6-6.9 4-26 23- 79 E a s t e r n Mean 9.2 95 274 ' 1S.S 4.4 1346 1, 6.7 6.7 50 399 21 b a s i n Range 7.3-11.7 12-109 216-347 0. 9-27. 8 3.1-6.3 715-3340 10-21 9.2- 8o2 6.6-6.8 35-64 188-608 Western Mean e.i 106 394 22.1 3.0 3377 16 6.1 6.7 60 307 48 b a s i n Range 9,2-12.3 01-141 297-322 12.0-41.0 3.4.-7.3 1091-1.\T% 12-22 4 .6- 7.5 6.3-6.8 34-87 164-611 B a s i n a l Mean ».4 103 353 20.0 4.0 2914 16 6.3 6.7 57 391 69 samples Range 5.7-12.4 00-132 257-403 10.7-37.0 3.3-7.0 926-9169 11-22 4 .6- 7.0 6.9-6.0 33-81 173-600 S h o r e l i n e Mean 3.4 ' SO 193 6.0 2.1 323 a 9.0 6.8 13 '* . 45 s amp 1e s Range 2.3-11.3 23- 99 100-373 2.1-17.3 1.3-3.4 231-11(0 4-16 0.3-11.3 6.6-6.9 3-24 10- 09 Mean i s a lognormal mean f o r O.M., Cu, Zn, Mo, Fe, Mn, and Pb; and an a r i t h m e t i c f o r temperature (Temp), pH, lake depth (Depth),.and d i s t a n c e from shore (DFS) # - number of samples range - lognormal (or a r i t h m e t i c ) mean ± 1 standard d e v i a t i o n 129 Organic matter content i s r e l a t i v e l y constant at 8.4% {Pig 36 and Table XIX). In proximity to Swannell Creek, pebbles are coated by red-brown (7.5YR4/4) Fe oxides. Nearby oozes are also red-brown. Moreover, the 10.2% Fe content of the s i l t f r a c t i o n of Swannell Creek sediment i s 50X higher than corresponding values i n Capoose Creek sediment. Apart from these observations, there i s no evidence of Fe and/or Mn accumulation i n the form of crusts or concretions. In core sections, the clay and s i l t - r i c h nature of the ooze can be i d e n t i f i e d by d i s t i n c t textural layering and grey colour. Consistency i s firm, except near the lake outflow where shallow water (3 m) turbulence promotes mixing of the upper 5 or 10 cm of s u r f i c i a l sediment. The dissolved content of Capoose Lake, estimated by bicarbonate (average 5 ppm), and sulphate (13 ppm) l e v e l s , i s low (Table XX). Organic productivity i s also low, and lake water i s c l e a r , an i n d i c a t i o n of low l e v e l s of dissolved organic matter (Nichol et a l , 1S75). Hater pH fluctuates between 6.7 and 7.0 within 20 m of the surface, but decreases to the 6.2 to 6.5 range at greater depths, p a r a l l e l l i n g a decline i n temperature to 4.5°C. A well developed thermocline at 5 to 8 m i s evident i n summer months and convective overturns are prominent i n spring and l a t e f a l l . Large volumes of water inflowing from 4 major and 8 minor streams are s u f f i c i e n t to assume a lake flushing rate (Rawson, 1960) of 1 year or l e s s . Although investigations of oxygen content and conductivity of lake water were unsuccessful, preceeding measurements suggest the lake i s an o l i g o t r o p h i c body (Nichol et a l , 1975). ., 130 e. Sample c o l l e c t i o n C o l l e c t i o n of lake sediment and water i s described i n Chapter 4. Areas of detailed studies i n the surrounding drainage basin are summarized on Fig 23 and 24. Two s o i l sampling traverses over the North Anomaly, each approximately 2300 m long, cross s o i l Cu - Mo anomalies previously outlined by Rio Tinto (Fig 26) . Although Lines 1 and 2 (Figs 27 and 28) crosscut l o c a l topography, regionally they follow the 1200 ± 110 m contour southwest of Mount Swannell, p a r a l l e l to the north shore of Capoose Lake and approximately perpendicular to southward flowing Rio and Swannell Creeks; S o i l samples from both banks of Swannell Creek were also taken to complement stream sediments collected at 120 m i n t e r v a l s along Swannell Creek. S o i l samples were also taken at regular i n t e r v a l s around the margins of Capoose Lake. S i m i l a r l y , stream and spring sediments were c o l l e c t e d at inflow points around the lake to complete the drainage survey. Pb and Zn anomalies west of Fawnie Nose Mountain were examined by 2 traverses (Lines 3 and 4, Figs 29 and 30) 4000 m i n t o t a l length. These contour the mountain i n the south but crosscut topography i n the north, terminating beside Capoose Creek. Additional sampling of major streams, seepages, and bank s o i l s completed work i n t h i s area. A separate investigation was conducted along Line 5 (Fig 30) north of Capoose Creek to evaluate low contrast-Cu anomalies southwest of T u t i a i Mountain. As before, a concurrent program of stream and bank sampling along Pyrite Creek, 100 m to the west, was also undertaken. Table XX Fi e l d determination of bicarbonate, suphate and pH i n stream and lake water samples STREAM WATER LAKE WATER AREA MEASURE- RANGE AVERAGE NUMBER OF RANGE AVERAGE NUMBER OF MENT OF PPM PPM SAMPLES PPM . PPM SAMPLES CAPOOSE pH 5.0-7.0 6.6 | 68 6.4-7.0 6.7 183 LAKE HCO3 0.02-8.0 j 4.0 I i 68 2.9-5.7 4.6 183 SO4 1.0-20.0 2.7 47 1.0-20.0 • 13.1 145 GREEN -LAKE pH -1.0-7.0 5.3 96 HCO3 0.02-6.6 0.9 96 so 4 1.0-50.0 13.4 96 PORTNOY pH 5.0-7.2 6.6 22 6.1-6.9 6.7 24 (Fish Lake CAMP 7.0-7.2 '7.1. 12 (Portnoy Lake) HCO3 0.02-31.9 14.5 22 6.4-12.8 10.. 6 24 (Fish Lake) 17.3-21.8 19.1 12 (Portnoy Lake) SO4 1.0-37.5 11.1 22 1.0-5.0 3.4 24 (Fish Lake) 20.0-25.0 22.1 12 (Portnoy Lake) range - actual range of an a l y t i c a l concentrations 1 3 2 1 T I t I i—i i-d O 8 K M F I G U R E 2 6 A : D I S T R I B U T I O N O F C O P P E R V A L U E S G R E A T E R T H A N 5 0 P P M I N S O I L S ( C O U R T E S Y A , T R O U P , R I O T I N T O ) F I G U R E 2 6 B : D I S T R I B U T I O N O F M O L Y B D E N U M V A L U E S G R E A T E R T H A N 5 P P M I N S O I L S ( C O U R T E S Y A , T R O U P , R I O T I N T O ) 1 3 3 8 K M F I G U R E 2 6 C : D I S T R I B U T I O N O F L E A D V A L U E S G R E A T E R T H A N 15 P P M I N S O I L S ( C O U R T E S Y A, T R O U P / R I O T I N T O ) O 8 K M F I G U R E 2 6 D : D I S T R I B U T I O N O F Z I N C V A L U E S G R E A T E R T H A N 150 P P M I N S O I L S ( C O U R T E S Y A. T R O U P , R i o T I N T O ) Table XXI Trace element content (ppm) of d i f f e r e n t s o i l horizons, Capoose Lake area, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c a c i d attack L-H horiaon Ah horizon As horizon Top of B horizon B around Capoose Lake Bf horizon , Bm horizon Bg horizon 0 horizon Cu Threshold Ran*e 2 3 0 2 3 7.1 - 70 3 6 5 28 7.8 - 100 90 14 5.6 - 3 6 3 0 0 26 - 1 3 0 1 0 6 . 27 13 - 55 240 55 26 - 1 1 5 3 5 0 6 5 2 9 - 1 5 5 195 80 5 0 - 1 2 5 7S0 1 0 0 36-280 Zn Threshold KG an. Range 85 2 5 1 3 - 4 7 145 2 6 11 - 6 0 38 1 5 9.3 - 24 95 3 4 2 0 - 5 5 180 4 5 2 2 - 9 0 9 5 39 2 5 - 6 0 75 3 1 19-48 55 2 5 1 7 - 38 1 0 5 34 19 - 6 0 Fa 1 Threshold Xaan 2.8 0.62 0.29 - 1.3 4 . 3 1 . 3 0.70 - 2 . 3 3.7 1.0 O . 52 - 1.9 4.1 1.7 1.1 - 2.6 3.7 1.2 0.73 - 2.2 3.9 2.1 1.6 - 2 . 9 3 . 7 1.6 1 . 0 - 2.4 3.4 1.4 0.86 - 2.1 4.7 1.9 1.2 - 2.9 Kn Threshold Main Ranye 970 1 9 5 90 - 4 3 5 820 1 1 5 42 - 3 0 5 1 5 5 80 55 - HO 480 140 75 - 260 1470 2 0 5 75 - 5 5 0 240 1 0 5 7 0 - 160 3 9 0 140 8 5 - 2 3 0 7 9 0 1 7 0 80 - 370 680 160 80 - 3 3 0 Pb Threshold .Mean Rar.ja 2 5 5.2 2.4 - 11 3 2 4 . 5 1.7 - 12 24 4.3 1.8 - 10 2 3 4.4 1 . 9 - 1 0 41 7 . 3 3 - 17 19 3.3 1.4 - 7.8 22 4.5 2.1 - 10 18 5.1 2.7 - 9.4 35 4.8 1.8 - 1 3 y.o Threshold Mom Ranje 120 10 2.9 - 3 4 9 0 8.4 2 . 6 - 2? 1 2 2.9 1 . 5 - 5.8 2 7 4.1 1 . 6 - 10 22 3.8 1.6 - 9.1 28 4.4 1.7 - 11 22 3.6 1.4 - 9 . 0 6 0 8.0 2.9 - 2 2 40 3.2 0 . 9 - 11 Jlucber of samples *9 . 14 6 1 7 0 19 5 0 86 11 16 mean - calculated for a lognormal d i s t r i b u t i o n range - lognormal mean + 1 standard deviation threshold - >(mean + 2 standard deviation i n t e r v a l s ) T O P O F T H E C H O R I Z O N B F H O R I Z O N B G H O R I Z O N  F I G U R E 2 7 A : V A R I A T I O N O F C O P P E R ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , L I N E 1 B M H O R I Z O N A H H O R I Z O N L - H H O R I Z O N 2 4 0 0 F E E T 5 0 0 M LANDSCAPE SURFACE z 4800 O 4600 r- L J 4400 > \7 4200 _ J ' 4000 ^ ' 3800 1000 500 E Q . o N VARIATION OF Z INC IN DIFFERENT SOIL HORIZONS — T O P O F T H E C H O R I Z O N BM H O R I Z O N B F H O R I Z O N A H H O R I Z O N | — 2 ^ ° ° F E E , T — ! B G H O R I Z O N L - H H O R I Z O N 5 0 0 M F I G U R E 27B: V A R I A T I O N O F Z I N C ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , £ I N E 1 LANDSCAPE SURFACE VARIATION OF MOLYBDENUM !,-,< DIFFERENT SOIL HORIZONS T O P O F T H E C H O R I Z O N B F H O R I Z O N B G H O R I Z O N B M H O R I Z O N A H H O R I Z O N L - H H O R I Z O N 2 4 0 0 F E E T 5 0 0 M F I G U R E 2 7 C : V A R I A T I O N O F M O L Y B D E N U M ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , L I N E 1 - T O P O F T H E C H O R I Z O N B M H O R I Z O N _ B F H O R I Z O N — A H H O R I Z O N | — | — r~ B G H O R I Z O N L - H H O R I Z O N 5 0 0 M F I G U R E 2 8 A : V A R I A T I O N O F C O P P E R ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , L I N E 2 L A N D S C A P E S U R F A C E 32 00 . — 915 VARIATION O F . ZINC IN D I F F E R E N T SOIL H O R I Z O N S 1 0 0 0 : : : : ;  5 0 0 N 5 T O P O F T H E C H O R I Z O N B F H O R I Z O N B G H O R I Z O N B M H O R I Z O N A H H O R I Z O N L - H H O R I Z O N 2 4 0 0 F E E T 5 0 0 M F I G U R E 2 8 B : V A R I A T I O N O F Z I N C ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , L I N E 2 e Q . CL UJ Q CD O 1000 5 0 0 100 5 0 LANDSCAPE . SURFACE VARIATION OF MOLYBDENUM INDIFFERENT SOIL HORIZONS T O P O F T H E C H O R I Z O N B F H O R I Z O N B G H O R I Z O N B M H O R I Z O N A H H O R I Z O N L - H H O R I Z O N 2 4 0 0 F E E T 5 0 0 M F I G U R E 2 8 C : V A R I A T I O N O F M O L Y B D E N U M ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , L I N E 2 O 141 3. Geochemical r e s u l t s a. Geochemical dispersion from the North Anomaly The North anomaly ( f i g 22) i s defined as the area between Swannell and fiio Creeks, and i s the most s t r i k i n g of the Cu anomalies (Pig 26) associated with granodiorite bedrock of the capoose Lake watershed (Boyle, 1971). Values (Table XXI) commonly greatly exceed regional averages for Cu and Mo of 24 and 1 ppm, respectively (Boyle and Troup, 1975). Trace element content of s o i l s i s controlled by a variety of l o c a l f a c t o r s : o r i g i n and thickness of the overburden, pedology, proximity to topographic i n f l e c t i o n s and nature of underlying geology and mineralization; - Ground surface along Line 1 (Fig 27) i s underlain by granodiorite bedrock, and r e l a t i v e l y t h i n g l a c i a l or c o l l u v i a l deposits. C o l l u v i a l material i s greatest i n extent and thickness i n the west and near Swannell Creek whereas g l a c i o f l u v i a l deposits are most prominent i n cuts along Hio Creek. Trace metal l e v e l s associated with g l a c i a l deposits are low. By comparison^ c o l l u v i a l material or bedrock areas, commonly indistinguishable by p e c u l i a r i t i e s i n metal d i s t r i b u t i o n , are usually r e l a t i v e l y metal-rich. However Cu, Zn and Ho l e v e l s associated with l o c a l l y derived overburden and intermittently exposed granodiorite i n the west are r e l a t i v e l y low (Figs 27, 31 to 33; Table XXI). Values increase to 450 ppm Cu, 100 ppm Zn and 50 ppm Mo i n the «C» horizon near Swannell Creek. Cu and Zn anomalies l i e east of the creek i n an area of abundant outcrop whereas by contrast, Ho accumulation distinguishes a prominent seepage area on the west bank of the T O P O F T H E C H O R I Z O N B M H O R I Z O N 2 4 0 0 F E E T B F H O R I Z O N — A H H O R I Z O N | — r -B G H O R I Z O N L - H H O R I Z O N B U U M F I G U R E 2 9 A : V A R I A T I O N O F C O P P E R ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , L I N E 3 T O P O F T H E C H O R I Z O N B F H O R I Z O N • B G H O R I Z O N B M H O R I Z O N - — A H H O R I Z O N L - H H O R I Z O N 2 4 0 0 F E E T 5 0 0 M F I G U R E 2 9 B : V A R I A T I O N O F Z I N C ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , L I N E 3 T O P O F T H E C H O R I Z O N B M H O R I Z O N B F H O R I Z O N - A H H O R I Z O N I 2 4 0 0 F E E T , B G H O R I Z O N L - H H O R I Z O N 5 0 0 M F I G U R E 2 9 C : V A R I A T I O N O F M O L Y B D E N U M ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E / - 8 0 M E S H F R A C T I O N / L I N E 3 T O P O F T H E C H O R I Z O N B M H O R I Z O N — B F H O R I Z O N A H H O R I Z O N | — 2 4 0 0 F E E T — B G H O R I Z O N L - H H O R I Z O N 5 0 0 M F I G U R E 2 9 D : V A R I A T I O N O F L I N E 3 L E A D ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , Q . CL LU Q. CL O O 1000 5 0 0 100 5 0 10 5 L A N D S C A P E S U R F A C E 4 - r - N -VAR1ATI0N OF COPPER IN D I F F E R E N T SOIL H O R I Z O N S J — r~— LINE 5 LINE 4 T O P O F T H E C H O R I Z O N B F H O R I Z O N B G H O R I Z O N — — B M H O R I Z O N A H H O R I Z O N L-H H O R I Z O N 2 4 0 0 F E E T 5 0 0 M F I G U R E 3 0 A : V A R I A T I O N O F C O P P E R L I N E S 4 A N D 5 ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E / - 8 0 M E S H F R A C T I O N , z 5800-O 5600-> - L J 5400-< U J UJ UJ CL o NI 520 0-5000-4800-1 0 0 0 -5 0 0 . ; 100 -5 0 -10 5 LANDSCAPE SURFACE _GRANODTORITE C f l P O Q 5 E -N-ACQ ci^ egK VARIATION OF IN TJIFFERENT SOIL HORIZONS LINE 5 T O P O F T H E C H O R I Z O N B F H O R I Z O N B G H O R I Z O N B M H O R I Z O N A H H O R I Z O N L-H H O R I Z O N 2 4 0 0 F E E T T— 5 0 0 M F I G U R E 3 0 B : V A R I A T I O N O F L I N E S 4 A N D 5 Z I N C ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E / - 8 0 M E S H F R A C T I O N / £ LANDSCAPE SURFACE T O P O F T H E C H O R I Z O N B M H O R I Z O N B F H O R I Z O N — • — A H H O R I Z O N B G H O R I Z O N L - H H O R I Z O N F I G U R E 3 0 G V A R I A T I O N O F M O L Y B D E N U M ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , L I N E S 4 A N D 5 2 4 0 0 F E E T 5 0 0 M 2 O < UJ > u_ LJ _J UJ £ CL Q < UJ N. 5800 : 5600-5400-52001 5000; 4800-1000 -5 0 0 : 100 -5 0 = 10 -5 -LANDSCAPE SURFACE - S - r - N - — -GRANODIORITE CAPOOSE CREEK. Ac-'Q CREEK V O L C A N I C S ANOMALY CREFK VARIATION OF L E A D DIFFERENT SOIL HORIZONS _LINE_5_ A •LX ni,8 non s \<oMo J I5B5 15 24-14 « _L!NE_4 T O P O F T H E C H O R I Z O N B F H O R I Z O N B G H O R I Z O N B M H O R I Z O N A H H O R I Z O N L - H H O R I Z O N 2 4 0 0 F E E T 5 0 0 M F I G U R E 3 0 D : V A R I A T I O N O F L E A D ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , L I N E S 4 A N D 5 150 creek. Line 2 (Fig 28) crosses s i m i l a r topography as Line 1. C o l l u v i a l material i s rarer and g l a c i o f l u v i a l deposits are more common, p a r t i c u l a r l y at lower elevations i n the east. Seepage and boggy areas are prominent i n the west, along the west bank of Swannell Creek, and between Swannell and Rio Creeks. Trace element leve l s are greatest i n the west, as s o i l s overlying bedrock are Cu-rich compared to the North anomaly proper. Although Cu values commonly increase with depth to a maximum of 600 ppm, Cu content of 'L-H* samples overlying metal-rich mineral horizons i s r e l a t i v e l y impoverished at below 25 ppm l e v e l s . By contrast^ Cu content of the * L-H* i s as high as 68 ppm, and the 'Ah* contains up to 520 ppm near Swannell Creek, i n association with water-saturated overburden. S i m i l a r l y , Mo accumulation to 180 and 350 ppm i n the *L-H* and * Ah* horizons, respectively, west of Swannell Creek represents the most s t r i k i n g Mo anomaly north of Capoose Lake. Extent of Cu and Mo enrichment i n s o i l s adjacent to Swannell Creek depends on horizon sampled. Mo level s are enhanced i n the••L-H*, ranging from 10 to 50 ppm, but diminish to less than 5 ppm i n the *C* horizon. By contrast, Cu concentrations are r e l a t i v e l y low i n the *L-H* horizon, but increase to 900 ppm with depth. Superimposed on these d i s t r i b u t i o n s are trends r e f l e c t i n g pedogenic processes. For example, the *Ae* horizon i s impoverished i n Cu, Zn, Pb and Mo compared to overlying and underlying zones (Table XXI) whereas the *L-H* i s r e l a t i v e l y poor i n Cu and Fe, but contains the highest Mn, Pb and Mo content of the p r o f i l e . Underlying *Ah* 151 samples are s i m i l a r l y impoverished i n Cu and Fe, but enhanced in Pb and Ho with respect to »B* horizons. Contents of Cu, Zn, Mn, Pb and Mo i n various »B' horizons are s i m i l a r . However Fe concentrations are notably lower i n the •Bm* compared to the •Bf 1 because Fe enrichment i n the l a t t e r i s the c r i t e r i a used to di s t i n g u i s h •Bf* and »Bm* horizons (Canada Department of Agriculture, 1 9 7 0 ) . B y contrast, the •Bg» horizon i s depleted i n Fe, r e f l e c t i n g solution of Fe oxide phases promoted by reducing conditions during prolonged periods of saturation. Despite diminished l e v e l s of Fe oxides, Mn and Mo a t t a i n and Cu approaches maximum l e v e l s within the *Bg» compared to other mineral horizons. The •C* horizon contains s i m i l a r Zn, Fe, Hn and Pb values to the top of the *BI horizon. Trace element retention of selected p r o f i l e s was evaluated by sequential extraction studies. In general, 50% or more of the • t o t a l 1 Cu, Zn, Fe and Hn content of mineral horizons appears associated with the s i l i c a t e residue. However a high proportion of these metals and Mo are bound by organic matter i n organic-rich 'L-H' and •Ah' horizons. Although general trends are e a s i l y summarized, s o i l p r o f i l e s may exhibit p e c u l i a r i t i e s . For example, metal contents diminish with depth in p r o f i l e 302 to 304 (nomenclature denotes one s o i l p r o f i l e comprised of samples 302, 303 and 304; see Table XXII) near a seepage zone. Cu accumulation to 650 ppm i s associated with organic matter enrichment whereas i n deeper horizons, trace elements appear bound to amorphous and c r y s t a l l i n e Fe oxides. P r o f i l e 488 to 491 adjacent to Swannell Creek i s also Cu-r i c h , and contents increase with depth. Apart from Cu Table XXII Sequential molybdenum extraction of copper, z i n c , i r o n , manganese and (percent extraction) from selected s o i l p r o f i l e s , Capoose and Green Lake areas < PROPORTION OF COPPER S EXTRACTED BY S E Q U E N T I A L j * R E A G E N T NUMBER 1 2 3 1 5 6 7 S S P R O P O R T I O N OF Z I N C E X T R A C T E D BY S E Q U E N T I A L REAGENT NUMBER P R O P O R T I O N OF IRON E X T R A C T E D B Y S E O U E N T I A L REAGENT NUMBER P R O P O R T I O N OF M A N G A N E S E § M E X T R A C T E D B Y S E Q U E N T I A L £ *g R E A G E N T NUMBER C £ P R O P O R T I O N O F ^ O L Y S S E N U M g E X T R A C T E D B Y S E Q U E N T I A L < R E A G E N T NUMBER t 0 l_j a. -o •5 •d I u < 0. < •JL j; L J a. 0 u o .1 2 3 1 5 6 7 O t_l 3 u 1 2 3 1 5 6 > d * — i o L J 3 ; ? 1 J ; i i > 6 7 - . }_ O O t-> i~> 1 2 3 1 5 6 7 o o T. O < CO 6a 01 01 01 C9 08 00 00 14 32 62 13 01 00 44 05 01 35 031 167 51 04 C3 C5 "5T ST -rr-- r r HI ST cM 54 bl C6 sr ""ST "ST" 00 06 00 00 90 12 119 00 00 00 31 16 CI 52 061 149 CO OO 02 09 C4 12 73 51 76 00 00 00 24 03 32 40 10 62 55 C2 18 CC 10 00 00 70 21 56 00 00 00 37 09 00 53 119 145 cc CO CI C5 C2 06 66 112 K 4 37 CO CC 61 CI CO CO 20 Bl U3 00 oc 28 CO 00 69 19 23 00 oo 00 41 09 CO 49 107 155 CO OC CI 11 03 06 78 133 124 27 00 00 71 01 OO 00 20 d7 47 06 CO 01 18 CO 00 66 9 126 01 00 00 49 24 00 25 085 128 17 CI C4 13 04 02 59 57 120 55 CI 01 18 C2 10 OC 4 202 12 00 01 0 0 03 00 00 95 44 57 00 ou 00 27 25 00 48 167 140 00 00 00 02 03 03 51 90 115 12 00 00 29 55 04 00 9 67 5C ; 1 01 16 01 09 00 00 73 22 61 00 00 00 35 08 00 56 164 139 CC CC CC C6 02 05 eo 104 1C8 55 CO 00 41 04 CO 00 3 163 CO C5 00 04 00 00 91 35 98 00 00 00 30 04 00 66 230 142 CO OC CI C3 02 02 92 230 1C5 21 CO 00 77 02 00 00 19 54 46 27 10 c 16 00 00 4* 31 88 05 00 00 46 20 CI 28 C77 148 47 02 ce 07 02 CI 33 174 51 88 CC CC 10 01 00 00 20 0 92 37 01 15 01 22 00 00 60 22 97 00 00 00 49 23 00 27 049 130 05 03 Co 16 03 03 64 76 122 00 CO 00 51 09 00 OC 27 ' 42 00 03 00 05 00 00 91 49 50 CO 00 00 37 19 CO 43 186 132 CO CC CO 02 C2 C3 91 92 118 15 OC 00 33 52 uo 00 4 i l l 49 01 02 00 03 00 00 93 41 63 00 00 00 27 15 00 57 177 149 CC CC CC C2 02 04 92 107 121 30 CO CC 62 cn cu 00 4 t>0 47 00 00 00 26 CO 00 73 16 70 00 00 00 42 09 00 49 141 154 00 00 CC C9 02 06 62 120 120 27 00 00 66 0 1 CO CC 2 132 IS 62 CO 08 04 00 00 06 36 77 31 01 01 27 11 02 27 030 77 79 C7 £ « C4 01 01 03 401 50 95 CO CO CO CO CO CC lit 99 4 00 00 00 06 00 00 94 75 122 00 00 00 32 30 00 38 510 121 CO 00 01 35 29 02 25 SCC 74 17 00 00 25 47 00 00 350 97 41 00 00 00 23 00 00 77 17 37 00 00 00 26 11 00 63 066 i t c CI CC CI 12 Ci 07 78 1C6 119 32 00 00 61 01 CO 06 18 91 t2 CO 00 01 17 CO 00 02 14 49 00 00 00 20 13 00 67 057 156 CI OC CI c ; 02 OS 83 93 120 42 CO 00 52 01 CO 05 5 Kt> cS 73 05 03 06. CO 00 13 46 133 04 00 00 58 17 CO 20 C65 137 61 02 CI C6 01 01 23 125 134 84 CC CO 00 04 12 00 4 01 43 02 22 00 00 31 17 115 00 00 00 49 17 00 33 116 159 CI 03 02 lo 05 02 74 51 139 30 00 00 62 CS 00 00 3 au 44 02 32 00 19 00 00 47 39 60 00 00 OC 34 10 CC 56 2C1 127 CO CC 00 07 C2 CS 65 95 116 30 CO uo 62 06 00 00 i HQ 4C 00 00 00 07 00 00 92 53 91 oo 00 00 24 14 03 62 228 136 01 CO 01 05 C3 01 00 173 ICS C3 CO 00 03 16 CO 00 3 40 2 5 68 04 07 07 00 00 12 51 02 28 01 00 23 08 08 29 C3 52 81 04 C4 C2 CI 02 05 161 l e i 95 CO 00 CO 04 CO 00 26 149 1C 18 03 03 12 00 00 64 39 115 14 00 00 28 13 01 44 110 116 25 03 C5 14 04 07 45 90 1C1 75 00 CO 10 01 13 CO 14 1U2 CO 00 03 17 CO CO 7S 22 52 00 00 00 23 12 CO 64 OEt 130 CI CC CI 04 C2 Cb- 83 69 125 CO CO 00 00 96 00 00 5 3 56 CI 05 10 00 00 28 30 106 C6 00 00 39 13 CI 40 093 99 59 C7 C4 CS 02 01 22 104 1C5 86 00 00 08 01 C5 CC 1C 169 . 4C 04 00 02 24 00 00 70 26 96 01 00 00 38 17 00 44 155 111 06 C3 01 lo C4 C4 6 6 63 112 44 00 00 J5 03 17 00 7 i l l 68 CC 00 CC 15 CO 00 84 36 00 00 uo 2d 13 00 59 2eC CC CC CI 11 C4 03 01 91 39 00 CC 5 5 C6 CO 00 3 01 00 OC 0) CO 00 93 tiO 121 00 CO 00 2 2 11 00 67 250 121 00 CO 02 02 u > •li 113 luo 00 uo 00 43 5 7 uu 00 6 43 it 01 04 oo 15 00 00 DO 27 74 00 00 00 32 08 00 60 203 111 01 OC CC C9 01 05 82 122 EO 00 CO OC 92 08 CO 00 4 54 ; i CC 00 oo OS CO 00 95 33 13S 00 00 00 31 06 00 63 193 114 01 OC CI C7 03 02 f:6 126 04 91 00 00 00 08 00 00 1 20U H 52 00 06 10 00 00 32 41 51 09 00 00 45 11 02 22 031 33 77 ct C5 C3 CO 01 07 29 6 56 59 CO CO 00 01 00 00 45 68 13 00 00 OC 14 00 00 05 103 85 00 00 00 32 14 00 54 205 l i s 00 00 C5 31 03 04 56 149 67 UJ 00 00 63 06 00 31 5 63 01 00 00 04 00 00 95 88 65 CO 00 00 28 04 CO 68 245 120 CC CC CI 04 C2 CI 52 1/6 et CC uo uu U4 1 5 OU 00 b 19 4 1 00 01 00 04 00 00 95 T> 91 00 00 00 29 05 00 o7 226 123 OC CC CI C* 02 CI 90 180 75 78 CO CO 00 21 CO CO 1 44 NORTH ANOMALY 540 541 LH 0 2 • AH 2 8 75 04 01 C5 01 05 ca 33 od 11 06 06 36 542 •SI 316 CO C2 CI 2 2 13 14 3e 543 8G1620 00 03 01 50 00 26 20 545 AH I 3 45 C3 C2 17 cc CO 32 55C OF 310 OC CO 00 20 00 27 52 551 S'l 1018 OC C2 CI 22 02 27 47 552 C 1824 CO CO oo 23 03 22 51 557 LH 0 1 51 03 02 13 00 C2 30 550 AH 1 3 33 C4 03 19 uu UJ 36 555 BF 31C OC C2 CI 26 CO 20 50 56C C 1020 CO CI 01 24 OS 26 44 561 C 2025 00 C2 01 25 00 34 38 566 LH 0 1 06 CO CC C4 oo C5 05 5c7 AH 1 2 CI CC 02 19 ou 14 64 568 DM 220 02 C6 07 3E CC 28 19 569 8.«2023 ' 00 Gl 06 39 05 29 21 4es Lri 0 2 7e CI 01 07 00 CS OS 489 A5 2 4 00 C3 04 50 00 07 27 45C 8F 414 CC CI CO 36 00 33 29 491 811424 CC CO 00 20 02 16 62 202 LH 0 1 83 CO CI 04 00 C6 05 303 AH 1 I 72> 01 01 06 01 04 15 3C4 8" 212 04 C3 CC 44 11 22 17 4 04 LH 0 1 59 01 01 07 00 05 26 405 AH 1 2 32 C2 02 19 00 07 38 4Ct »= 2 7 05 C2 c:- 30 CC C) S3 407 OF /IS 02 UU UO 13 0 1 21 64 408 8-1519 CI CO CO 23 00 21 54 405 C 1925 CO CO 01 IS 00 CS 72 415 LH C 1 51 C3 02 C4 00 C2 37 416 AH 1 8 .02 CI 01 21 00 01 73 417 BH 013 CC CC CC 09 oo 02 89 416 C 1218 CI CC uu 05 OC 02 87 23 103 21 80 20 55 33 50 9 IC6 120 66 140 72 602 63 73 81 67 71 68 105 520 116 62 60 53 54 21 150 17 50 100 51 287 60 170 99 650 119 152 6C 13 12J 16 110 13 126 72 150 75 146 ICC 10 77 36 70 149 97 119 65 T a b l e X X I I c o n t i n u e d G R E E N LAKE ANOMALY 3 6 2 O " 0 6 3 6 3 0* 6 1 0 2 6 4 8 H 1 C 1 2 3 6 5 O f 1 2 1 6 3 b 6 C K 1 6 2 1 3 6 7 C 2 1 2 5 1 2 5 AH 0 1 C 9 2 6 8 M 1 0 I 4 9 2 7 C 1 4 2 C 9 1 6 AH 0 3 9 1 7 I t 1 1 5 1 6 6F 6 1 4 9 1 9 0 H 1 4 2 O 8 5 5 L H 0 2 0 6 0 AH 2 4 6 6 1 [IX 4 1 0 . 8 6 2 C 1 C 1 6 1 0 2 3 L H 0 1-1 0 2 4 AH 1 2 1 0 2 5 6F 2 5 , 1 0 2 6 C 5 1 5 : 1 0 2 7 C 1 5 3 C ca CO 01 13 0 9 36 38 34 76 0 0 0 0 0 0 11 0 0 0 0 89 6 9 7 0 0 0 0 0 0 0 29 4 3 0 0 2 0 2 2 1 1 1 7 CC C C C l 1 C 0 2 0 5 8 0 179 1 2 6 C C CC 0 0 31 6 S CO 0 0 3 5 6 4 2< 0 4 0 0 01 16 0 0 32 4 6 2 6 70 0 0 0 0 00 0 9 0 0 0 0 9 0 92 4 1 0 0 0 0 0 0 2 6 39 0 0 3 2 2 2 2 1 2 1 0 0 0 0 C l 10 0 4 0 5 7'J 1 5 4 1 2 7 29 0 0 00 22 4 9 CO 00 16 7S 2 4 2 4 CC 01 24 11 17 23 15 I O C 0 0 00 OC 0 4 CO CO 9 0 2 0 9 3 0 0 00 0 0 38 35 0 0 2 7 1 1 7 134 C I OC C l 0 9 C 3 02 64 eo 1 5 3 OC 0 0 00 4 0 6 0 uo 0 0 8 6 2 2 4 CO CC 01 1 9 2 3 28 26 19 74 CO oo 00 0 8 oo 0 0 9 1 4 5 5 1 0 0 0 0 0 0 4 2 3 4 0 0 2 3 2 5 1 1 2 1 C C 0 0 C l 07 0 6 0 6 79 13 6 6 2V 00 00 11 5 9 00 0 0 13 6 8 24 0 0 0 0 0 1 16 0 0 41 40 2 3 75 CO CO OC 0 9 0 0 0 0 5 0 4 8 7 4 OC 00 CO 2 7 34 0 0 3 8 2 3 2 1 2 8 0 0 OC C l C t 05 05 8 2 1 4 2 1 2 0 CO O J uo 0 9 9 1 uo GO 14 25 28 c c CO C I 10 0 0 3 3 4 6 2 8 74 0 0 01 0 0 0 9 0 0 0 0 9 0 5 6 9 5 0 0 0 0 0 0 17 41 0 0 4 1 192 1 3 6 0 0 0 0 0 1 0 6 C 3 0 4 C6 1 5 9 1 6 1 0 0 0 0 uo 19 81 0 0 00 2 0 52 31 2 0 01 0 0 17 0 0 2 5 27 67 96 0 0 0 0 0 0 14 0 0 0 0 86 1 5 0 6 5 CO 0 0 0 0 2 9 36 0 0 3 4 2 3 5 1 3 9 OC CC CC 0 0 0 1 01 9 8 4 3 4 2 S 3 53 0 0 CC 31 16 CO CO s 6 4 11 0 7 C3 01 38 01 3 7 14 3 3 0 83 0 0 0 0 0 1 10 0 0 0 0 61 8 0 2 8 00 0 0 0 0 2 0 4 2 0 0 3 8 2 5 3 1 3 6 CC 0 0 C l C C 0 2 01 9 5 2 8 1 2 5 6 2 0 0 0 0 0 3 6 4 5 0 0 00 7 0 0 2 0 CO CC 01 24 0 6 34 3 0 I C O 63 0 0 01 0 1 I S 0 0 0 0 83 1 9 0 6 7 0 0 0 0 0 0 2 0 4 5 0 0 3 5 2 9 5 1 5 1 0 0 OC C4 C4 0 1 00 9 1 1 4 5 2 3 1 1 0 0 CO CC 9 9 0 0 0 0 0 0 5 3 0 2 t 3 6 CO C I 17 0 0 2 3 2 3 16 1 2 2 03 0 0 0 0 13 0 0 0 0 6 4 1 0 0 5 6 0 1 0 0 0 0 4 3 0 3 0 1 52 1 8 8 1 C 6 C I 0 1 c : 3 2 0 2 10 52 5 0 7 1 1 6 6 ] CO 0 0 3 7 0 0 oo 0 0 3 1 3 7 1 1 5 CO 01 13 0 0 32 3 9 18 OC 0 0 CO 0 0 0 8 0 0 0 0 91 I S O 52 0 0 0 0 0 0 31 31 0 0 3 7 2 1 2 1 3 4 CO C C C C 11 0 2 0 4 81 3 6 1 1 5 6 5 7 00 0 0 0 0 4 3 0 0 0 0 3 1 1 7 22 1 4 . CO C I 12 00 3 2 42 2 2 72 0 0 01 0 0 0 7 0 0 0 0 9 2 1 8 0 6 4 0 0 0 0 0 0 2 3 35 0 0 41 2 1 0 1 3 9 01 0 3 01 12 03 04 76 4 1 3 1 2 0 0 0 0 0 0 0 0 0 9 9 0 0 0 0 4 4 9 2 6 17 CO 0 0 1 6 0 0 3 5 2 7 62 8 7 CC CO 0 0 14 0 0 0 0 8 5 1 7 0 s a 0 0 0 0 0 0 2 6 3 9 0 0 3 5 2 3 2 1 4 C 0 0 CO c c C4 0 1 0 1 9 5 3 6 4 5 4 C 0 0 0 0 CO CO CO CO 0 0 3 I t 5 5 CC C3 15 0 0 14 12 23 1 C 7 10 GO 0 3 18 0 0 CO 6 9 22 1 0 4 0 8 0 0 0 0 5 4 C 3 C 2 3 2 1 1 6 1 1 2 C4 0 1 C l 0 5 0 2 ce 78 61 1 5 2 OU 0 0 0 0 0 0 0 0 0 0 0 0 3 1 0 3 27 3 2 CO 01 16 0 0 2 7 23 2 6 06 • 02 0 0 01 1 9 0 0 0 0 7 8 2 1 6 1 0 2 0 0 0 0 4 2 2 S 0 1 3 0 1 5 5 1 2 6 0 2 C I CO CO 0 2 0 8 6 7 6 5 1 6 4 16 CO 0 0 4 8 3 4 CO CO 3 21 0 8 0 0 0 1 21 0 0 3 0 4 0 3 8 70 0 1 CO OC 0 7 CO CO 9 3 2 8 6 0 0 0 0 0 CO 4 2 3 3 0 0 2 5 2 6 2 1 5 6 0 1 CO CC C C 0 4 0 6 8 8 1 2 4 1 1 3 OU CO 0 0 32 6 8 CO CO 7 4 4 19 10 0 0 0 0 16 OS 2 6 4 2 5 6 6 7 00 0 0 0 0 0 3 0 0 0 0 9 6 3 4 9 1 0 0 0 0 CO 2 3 52 0 0 2 4 3 4 2 . 1 4 9 0 1 C I CC CC C6 C4 o S 155 1 12 0 0 CC 0 0 11 8 9 0 0 0 0 7 6 3 2 C 6 5 0 0 01 23 0 0 OS 0 6 19 1 4 4 4 7 00 OS 1 8 CO 0 0 2 3 3 0 9 1 2 5 0 0 C I 2 0 0 8 0 3 4 2 0 4 7 ' 6 S 2 6 0 1 C4 0 9 0 1 0 6 5 3 6 6 1 4 6 0 0 OC 0 0 9 9 0 0 0 0 0 0 1 9 9 27 3 5 CO 02 4 5 oo 0 4 1 4 2 6 102 0 7 0 2 0 4 2 9 0 0 0 0 5 6 2 4 8 1 01 0 0 0 0 6 1 12 0 0 2 5 1 1 9 1 4 1 C2 0 1 C l 0 9 C2 C 6 6 0 5 6 I P S CO 0 0 OU 2 4 75 CO 0 0 1 2 0 1 46 0 3 CO 01 16 0 0 3 0 50 80 78 01 0 0 0 0 0 3 CO 0 0 9 5 4 2 77 0 0 0 0 0 0 2 1 31 0 0 4 7 2 7 ! 1 3 9 CC 0 0 C l C 2 C 3 C3 9 0 2 4 3 1 2 1 OC CO C C 5 6 4 3 CO CO 3 1 1 7 5 C C C CO 01 1 8 0 0 3 0 S I 9 0 81 0 1 0 0 OC CS CO 0 0 9 1 51 8 6 0 0 0 0 oo 1 6 31 0 0 5 3 2 7 0 1 4 2 CO 0 0 0 8 OS C 3 0 3 77 2 6 4 1 2 0 0 0 0 0 0 0 2 4 7 5 0 0 0 0 3 6 7 4 6 CC CC 01 2 0 0 3 18 SO 7 8 9 5 0 0 0 0 0 0 0 4 0 0 0 0 9 6 1 2 0 9 2 . oo 0 0 0 0 3 2 15 0 0 53 i t e U C CO OC ce 26 0 5 0 4 4 5 3 6 7 9 C 53 CO 0 0 4 2 0 5 CO 0 0 I 2 5 8 29 1. 3 . 5 . 7 . O r g a n i c a l l y bound m e t a l 2, Amorphous Mn o x i d e s 4, C r y s t a l l i n e Fe o x i d e s 6 S i l i c a t e r e s i d u e s E xchangeable m e t a l Amorphous Fe o x i d e s Hydrogen p e r o x i d e C o n c e n t r a t i o n * - ' t o t a l ' d e t e r m i n a t i o n by a s e p a r a t e n i t r i c / p e r c h l o r i c e x t r a c t i o n Comparison* - sum o f s e q u e n t i a l e x t r a c -t i o n v a l u e s / ' t o t a l ' d e t e r m i n a t i o n v a l u e X 100 153 enhancement to 287 ppm i n the •Bn* horizon, the section i s distinguished by 8-and 13 ppm concentrations of Zn i n a c i d i f i e d d i s t i l l e d water extracts of •Ae1 and •Bf* samples, respectively. Extraction of large amounts of weakly bound Zn i s an unusual feature along Line 1, although i t characterizes 3 of the 4 p r o f i l e s along Line 2. P r o f i l e 566 to 569 along Line 2 i s associated with enhanced Cu, Zn, Ho, Fe and Mn values of 520 ppm, 75~ppm, 350 ppm, 5.1% and 900 ppm, respectively, i n the •Ah1 horizon. These concentrations are 8X to 20X greater than those found i n the underlying *Bm*. Despite notable organic matter and Fe oxide (62% of t h e - • t o t a l ' Fe i s i n the form of oxide phases) accumulation i n the * Ah* horizon, most of the Cu and Zn i s contained within s i l i c a t e l a t t i c e s of the f i n a l residue. By contrast. Ho and Hn are l i b e r a t e d sympathetically with Fe. In deeper horizons within the same p r o f i l e , Zn, Fe and Mn are primarily lattice-bound whereas Cu and Mo are primarily held by amorphous Fe oxides. P r o f i l e 549 to 552 i s Cu-rich, with contents increasing from 9 ppm at surface to 602 ppm at depth. Zn, Mo, Fe and Mn concentrations also increase with depth, and a Mo content of 18 ppm i n the *C horizon i s abnormally high f o r t h i s depth. Although Mo i s primarily dissolved by hypochlorite and acid ammonium oxalate, more than 50% of the other elements are dissolved by the concluding n i t r i c / p e r c h l o r i c acid attack. Approximately 50% of the Cu also appears associated with Fe oxide phases. Nevertheless Cu content of the f i n a l residue i s greater than that found i n any other p r o f i l e along Line 2. In 154 addition, the p r o f i l e i s characterized by a high content of readi l y soluble Zn of 3 ppm. Section 540 to 543 contains consistently high (20 ppm) Mo concentrations, but i s r e l a t i v e l y impoverished i n Cu, Zn, Fe and Mn. Because samples were collected from the middle of a prominent bog, the p r o f i l e represents a contrasting environment to previously described well-aerated s o i l s . Zn, Fe and Hn concentrations are-bound primarily to s i l i c a t e l a t t i c e s of the f i n a l residue whereas Cu and Ho appear held by amorphous Fe oxidesv The Fe d i s t r i b u t i o n i s unusual because c r y s t a l l i n e Fe oxide phases comprise a r e l a t i v e l y minor f r a c t i o n of the sample compared to amorphous phases. Drainage anomalies along Swannell or Rio Creeks, within the confines of the North Anomaly, can be derived by mechanical erosion of metal-rich stream banks, or by deposition of solutes from groundwater. Of the bank s o i l s examined along Swannell Creek, only mechanical erosion of p r o f i l e s 566 to 569 and 488 to 491 are l i k e l y to lead to stream sediment anomalies. However complementary pairs of bank s o i l s and stream sediments are apparently unrelated because t h e i r sequential extraction properties are very d i f f e r e n t . Trace metal l e v e l s along Swannell Creek can be divided into two groups on the basis of sequential extraction studies., The f i r s t , comprising samples 620 and 632 near the headwaters of the creek, i s characterized by regionally anomalous l e v e l s of Ho, Fe and Hn (Tables XXIII-and XXIV; Figs 33 to 35) and reg i o n a l l y low values of Cu (Fig 31)-. The Hn and Zn (Fig 32) d i s t r i b u t i o n s are p a r t i c u l a r l y s t r i k i n g because a large proportion of these metals 155 are released by hydroxylamine hydrochloride* Hn oxides comprise 60% of the ' t o t a l 1 Hn content of sediment at upper elevations, declining to 45? over the North Anomaly proper. Further downstream; Zn, Ho, Fe and Hn values diminish to more average values. Over the North Anomaly, Cu and Ho values are commonly l e s s than 75 ppm and 6 ppm; respectively, and the anomaly i s only indicated by an enhanced Cu content of 277 ppm i n one sample adjacent to Line 2. Despite t h i s enhancement, the sample i s not distinguished by abnormal Cu enrichment associated with one or more sediment f r a c t i o n s . Cu values decline below the North Anomaly; but increase near the mouth of Swannell Creek (ID 15 - 128 ppm). In t h i s case, metal enrichment appears related to organic matter scavenging. The r e l a t i v e l y high proportion of Cu, Zn, and Ho held by amorphous Fe oxides of stream sediment as compared to adjoining mineral s o i l s (Fig 20) implies mechanical erosion of stream banks i s not the predominent factor c o n t r o l l i n g stream metal l e v e l s . Trace metal l e v e l s associated with s i l i c a t e residues are not as important i n stream sediments as i n s o i l s . Because trace element - amorphous Fe oxide associations are 5X to 10X stronger than trace metal - c r y s t a l l i n e Fe oxide r e l a t i o n s , despite the fa c t both components are present i n approximately equal amounts, amorphous Fe oxide scavenging appears to be a major control on trace metal l e v e l s i n streams. By contrast, Cu retention i n seepage sample 402 (Fig 23; Table XXIV), containing the highest Cu values of the North Anomaly (1850 ppm), indicates organic matter scavenging may also be s i g n i f i c a n t i n boggy or seepage areas. FIGURE 31A: NORTH ANOMALY - CAPOOSE LAKE COPPER (ppb) IN WATER TOPOGRAPHIC LEGEND -3700- CONTOUR INTERVAL 100 F E E T (3MJ CREEKS LOCAL GRID COORDINATES — T R A V E R S E LINES v- SAMPLE LOCATION 4 0 0 0 FEET J 1 0 0 0 M GEOCHEMICAL LEGEND L A K E W A T E R • less than 4 ppb 4 - 6 ppb • 7 - 1 6 ppb • more lhan 16 ppb S T R E A M . WATER «*.•' less lhan 7 ppb • 7 * 3 3 ppb 6 34 - 147 ppb © more lhan 147 ppb Figures 31 to 35: Coded intervals represent: <(x); (x) to (x+<r); (x+cr) to (x+20; and >(x+2<r) 157 FIGURE 31B: NORTH ANOMALY COPPER (ppm) IN SEDIMENTS. • TOPOGRAPHIC LEGEND -3700- CONTOUR INTERVAL 100 FEET (31m) • CREEKS LOCAL GRID COORDINATES TRAVERSE LINES v- SAMPLE LOCATION . W O ' F E E T I  1 1 0 0 0 M - CAPOOSE LAKE 80 MESH FRACTION GEOCHEMICAL LEGEND LAKE SEDIMENT less lhan 70 ppm • 70-135 ppm ....) » 135 "245 ppm ;/ » more than 245 ppm STREAM SEDIMENT less thon 50 ppm • 50-110 ppm » 110-240 ppm 9 more lhan 240 ppm FIGURE 31C: NORTH ANOMALY - CAPOOSE LAKE COPPER (ppm) IN SOLS, -80,MESH FRACTION TOPOGRAPHIC LEGEND -370O CONTOUR INTERVAL 100 FEET (31m) • CREEKS — LOCAL GRID COORDINATES TRAVERSE LINES V SAMPLE LOCATION 0 CORE SAMPLE LOCATION » s-\ .r"\ S~\ GEOCHEMICAL LEGEND TOP OF THE B HORIZON less than 6 0 ppm . 6 0 " 130 ppm • 130 " 300 ppm e more lhan 300 ppm 159 FIGURE 32A: NORTH ANOMALY ZINC (ppb) IN TOPOGRAPHIC LEGEND -3700- CONTOUR INTERVAL 100 FEET (31m)' • CREEKS - — - LOCAL GRID COORDINATES • TRAVERSE LINES V- SAMPLE LOCATION . 4 0 0 0 FEET \  1 1 0 0 0 M - CAPOOSE LAKE WATER GEOCHEMICAL LEGEND LAKE WATER • less than 14 ppb • 14- 30 ppb ' • 31 - 63 ppb • more than 63 ppb ; STREAM WATER - — less than 8 ppb. . 8 - 28 ppb • 2 9 - 9 7 ppb © more than 97 ppb 160 FIGURE 32B: NORTH ANOMALY - CAPOOSE LAKE ZINC (ppm) N SEDIMENTS, -80 MESH FRACTION TOPOGRAPHIC LEGEND -3700- CONTOUR INTERVAL 100 FEET (31m) - — C R E E K S LOCAL GRID COORDINATES TRAVERSE LINES V- SAMPLE LOCATION . 4 0 0 0 FEET , 1 1 0 0 0 M I G E O C H E M I C A L L E G E N D LAKE SEDIMENT less than 250 ppm • . 250 - 480 ppm • 480 - 930 ppm • more than 930 ppm STREAM ' SEDIMENT. - less lhan 38 ppm • 38 - 65 ppm » 65 " 105 ppm & more thon 105 ppm FIGURE 33A: NORTH ANOMALY -} . >'- MOLYBDENUM (ppb) IN TOPOGRAPHIC LEGEND -3700- CONTOUR INTERVAL 100 FEET (31m) • • CREEKS LOCAL GRID COORDINATES — TRAVERSE LIMES v- SAMPLE LOCATION 4 0 0 0 FEET J 1 0 0 0 M CAPOOSE LAKE WATER GEOCHEMICAL LEGEND LAKE WATER ' JESS THAN 1 ppb • 1 - 3 PPb • 4-7 ppb • KCRE TEAS 7 ppb STREAM ' WATER LESS TEAM 1 ppbf I < ! @ MORE THAN 1 ppb 162 FIGURE 33B: NORTH ANOMALY - CAPOOSE L A K E MOLYBDENUM (ppm) IN SEDIMENTS, "80 MESH FRACTION TOPOGRAPHIC LEGEND -3700- CONTOUR INTERVAL 100 FEET (31m) - — — CREEKS LOCAL 'GRID COORDINATES — TRAVERSE LINES "'! V - SAMPLE LOCATION 4 0 0 0 FEET J 1 0 0 0 M GEOCHEMICAL LEGEND LAKE SEDIMENT less than II ppm • 11-29 ppm • 30 - 80ppm » more lhan 80 ppm STREAM SEDIMENT - less than 4.4 ppm • 4.4 - II ppm II - 28 ppm more than 28 ppm e & 163 FIGURE 33C: NORTH ANOMALY - CAPOOSE LAKE MOLYBDENUM (ppm) IN SOILS, "80 MESH FRACTION TOPOGRAPHIC LEGEND ' -3700- CONTOUR INTERVAL 100 FEET (31m) • CREEKS LOCAL GRID COORDINATES • TRAVERSE LINES > v- SAMPLE LOCATION 4 0 0 0 F E E T 1 0 0 0 M J GEOCHEMICAL LEGEND TOP OF THE B HORIZON less than 41 ppm 41 - 10 ppm 10-27 ppm more than 27 ppm 164 'FIGURE 34A: NORTH ANOMALY - CAPOOSE LAKE IRON (ppb) IN WATER TOPOGRAPHIC LEGEND -3700- CONTOUR INTERVAL 100 FEET (31m) -s CREEKS . LOCAL GRID COORDINATES - ~ — TRAVERSE LINES . ' ' SAMPLE LOCATION v-4 0 0 0 FEET 1 0 0 0 J M GEOCHEMICAL LEGEND LAKE WATER • less than 416 ppb • 416 - 2430 ppb • 2431 - 14200 ppb • more • thdh 14200 ppb STREAM WATER - less than 348 ppb • 348 - 1870 ppb • 1871 - 10100 ppb © more fhon 10100 ppb FIGURE 34B: NORTH ANOMALY - CAPOOSE LAKE IRON (%) IN SEDIMENTS, "80 MESH FRACTION f. TOPOGRAPHIC LEGEND -3700- CONTOUR INTERVAL 100 FEET ' CREEKS ; — LOCAL GRID COORDINATES • TRAVERSE LINES V- SAMPLE .LOCATION , 4 0 0 0 FEET , | 1 0 0 0 M | GEOCHEMICAL LEGEND ,i LAKE SEDIMENT "i • less than 32 % • 3 2 - 6 0 % • • 60-113% ' • more than 113 % STREAM SEDIMENT - less than 2-2% • 2-2-3-8% «> 3-8-6-5% & more lhan 6-5% 166 FIGURE 35A: NORTH ANOMALY MANGANESE (ppb) IN T O P O G R A P H I C L E G E N D -3700- CONTOUR INTERVAL 100 FEET (31m) — CREEKS LOCAL GRID COORDINATES • TRAVERSE LINES X - SAMPLE LOCATION i 4 0 0 0 FEET J 1 0 0 0 M CAPOOSE LAKE WATER G E O C H E M I C A L L E G E N D LAKE WATER • less than 64 ppb • • 64 - 520 ppb • 521 - 4270 ppb • more than 4270 ppb STREAM WATER — less lhan 6 ppb • 6 - 3 4 ppb 9 35 - 215 ppb © more lhan 215 ppb 167 FIGURE 35B:NORTH ANOMALY MANGANESE (%) IN SEDIMENTS, TOPOGRAPHIC LEGEND -370o- CONTOUR INTERVAL 100 F E E T (31m) • CREEKS L O C A L GRID COORDINATES • — — T R A V E R S E LINES V SAMPLE LOCATION . 4 0 0 0 F E E T , 1 1 0 0 0 M CAPOOSE LAKE 80 MESH FRACTION GEOCHEMICAL LEGEND L A K E SEDIMENT • less • than O 13% • OB-0 5 0 % • 0 5 0 - I 91 % • more than 191 % S T R E A M SEDIMENT - less than 0 016% • 0 0 1 6 - 0 0 4 5 % © 0 0 4 5 - 0 1 3 ? . % & more than 0 132% FIGURE 36: ORGANIC NORTH ANOMALY MATTER (%) IN TOPOGRAPHIC LEGEND -370O- CONTOUR INTERVAL 100 FEET (31mJ — CREEKS LOCAL GRID COORDINATES — TRAVERSE LINES V- SAMPLE LOCATION - CAPOOSE LAKE LAKE SEDIMENT GEOCHEMICAL -LEGEND • less than 67 %-• 67 - 12 4 % • 12 5 - 231 % © more lhan 231 % no sample data 169 Table XXIII Comparison of trace element content (ppm) of Capoose, Fish and Portnoy Lake area stream sediment, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid digestion Capoose Lake area Green Lake area Portnoy Camp Cu Threshold Hean fiange 240 50 24-110 240 50 23-110 430 80 35-190 Zn Threshold Bean fiange 105 38 22-65 700 80 28-240 115 39 23-66 Fe % Threshold Mean Range 6.5 2.2 1.3-3.8 15.4 2.8 1.2-6.5 7.2 2.1 1.2-3.9 Hn Threshold Hean Range 3900 U50 155-1320 2100 240 80-700 2800 365 130-1000 Pb Threshold Hean fiange 26 5.7 2.7-12 175 18 5.9-55 Mo Threshold Hean fiange 28 4.4 1.8-11 10 2.7 1.4-5.2 110 12 3.8-36 -Ag Threshold Hean Range 5.46 0.83 0.32-2.12 Number of samples 42 87 22 .mean - ca l c u l a t e d for a lognormal d i s t r i b u t i o n range - lognormal mean + 1 standard deviation threshold - >(mean + 2 standard deviation i n t e r v a l s ) Table XXIV Sequential extraction of copper, z i n c , i r o n , manganese and molybdenum (percent extraction) from selected stream and seepage sediments, Capoose:, Green, and Pish and Portnoy lake area C R E E K S E N T E R I N G CAPOOSE L A K E SWANNELL CREEK CREEKS D R A I N I N G GREEN L A K ANOMALY P R O P O R T I O N OF C O P P E R E X T R A C T E D sr S E O U E N T I A L R E A G E N T NUMBER P R O P O R T I O N OF Z I N C g « E X T R A C T E D BY S E Q U E N T I A L P * * REAGENT NUMBER § S P R O P O R T I O N OF IRON *g E X T R A C T E D BY S E Q U E N T I A L P REAGENT NUMBER | ca CC X . or 0. w < 0, UJ < a UJ < a: •j) a . •o l_l a. "6 u a . IJ a; . au r. O 1 2 J 1 5 S 7 . o o t—> 1 2 3 1 5 6 7 O l_J o t_> 1 2 3 1 5 6 7 O o 4-1 2 23 Cl 03 37 00 09 27 32 76 00 00 00 OS 00 00 92 45 62 CO 00 00 19 C6 CC 54 135 156 6 10 C5 05 43 00 12 16 E4 94 00 00 01 23 00 00 75 36 64 00 01 00 40 06 00 53 101 122 13 OU o 02 39 OU 19 23 23 7 J 111- 03 02 39 CO 00 55 36 47 CO 00 CO 39 09 00 51 226 125 15 32 C2 C2 25 00 05 26 120 S3 01 00 02 17 00 00 79 . 4U 72 00 00 00 28 09 00 62 206 133 31 14 05 42 00 03 32 56 92 00 00 01 OS 00 00 94 42 13S CO 00 00 29 06 00 64 131 143 23 4C Cl 02 33 00 07 17 26 90 01 00 02 48 00 00 47 96 65 CO 00 00 28 20 00 52 1E2 154 620 03 01 01 52 OC 16 26 34 62 CU 04 1C 3S 00 OC 49 54 39 00 00 00 41 24 CO 34 305 143 .632 OC C2 07 64 05 OS 13 53 66 00 01 09 34 00 00 56 42 40 00 00 00 25 07 00 68 414 116 640 00 Cl C5 66 00 13 11 71 63 CC Cl 07 38 00 00 54 29 37 00 CO OJ 44 08 CO 46 157 151 573 00 C4 08 55 us 09 17 277 10 00 U2 03 27 CO CO 68 28 57 CO 00 00 35 08 00 57 161 173 652 02 C2 09 61 C4 10 12 75 69 00 03 06 32 00 00 59 35 39 00 00 00 34 01 CO 65 262 161 19 32 02 02 29 00 05 26 12S 03 . 01 00 02 17 CO CO 79 48 72 oo 00 00 39 09 00 51 226 125 37* CC C2 06 45 Cl 15 23 149 58 oo 01 05 13 00 00 06 167 72 00 00 00 20 25 00 54 245 124 8*3 15 00 01 22 00 12 50 2a 63 00 01 01 25 00 00 73 2 50 60 00 00 00 21 27 00 52 226 148 242 05 Cl 00 37 CO 20 33 41 00 02 05 36 CO CO 57 560 00 00 CC 10 20 00 7C 441 620 CO CO 01 25 00 13 61 30 70 CO CO 00 05 00 00 95 74 69 00 00 00 33 32 00 35 640 135 1037 70 09 01 14 00 03 03 313 93 16 08 02 OS 00 CO 66 26 98 02 00 00 OS 01 02 66 03o 150 1023 Cl C l 01 33 oe 12 37 SI 75 00 00 01 11 00 00 87 22 89 CO 00 00 23 23 CO 45 143 142 1069 0* CC 01 44 00 12 39 23 65 00 00 OC 07 00 00 92 45 97 00 00 00 32 35 00 33 402 131 P R O P O R T I O N OF MANGANESE § M E X T R A C T E D BY S E Q U E N T I A L P *== P R O P O R T I O N OF MOLYBDENUM 5 13 09 15 36 CS Cl 15 33 C6 OC C l 13 01 00 25 25 03 01 tl 21 OC 00 62 21 Cl CC 45 25 13 09 15 38 NUMBER 1 5 6 7 CC 1-2= UJ u o o ul < a c_> 1 R E A G E N T NUMBER ' % 2 3 1 5 6 7 CC t-z Uf u o l _ J U) ct < a. 71 O i-J SAND - Z C l 03 3 4 417 1C3 16 CO 00 62 01 00 CO 4 65 2 3 01 06 60 117 127 CO 00 OU 23 08 69 00 15 60 75 C3 03 21 6J6 55 00 CO OU 53 03 59 CC 1 216 e 4 CJ C3 41 507 56 25 00 00 61 04 10 00 6 86 57 01 04 te 183 124 00 CO 00 S9 11 CO 00 5 56 4C 04 03 41 416 es OU 00 00 56 42 00 CO 5 33 t\ 03 Cl C4 26C5 1C6 05 01 Cl 56 3C CO Cl 20 78 • t 01 01 14' 1079 91 OU 02 01 90 02 00 00 7 103 70 C2 C2 20 472 94 Oil C2 04 85 03 00 05 5 41 74 02 03 2J 403 55 21 CO 00 76 01 OC 00 5 15U 13 02 01 26 555 52 07 01 02 60 01 00 00 6 154 66 03 01 21 6IJ6 59 00 00 00 50 03 39 00 . 6 06 57 02 01 05 3802 04 11 00 00 34 55 00 00 22 07 40 05 C l 60 6 15 128 26 CO 00 40 14 OO 00 b 124 20 04 02 45 1363 35 00 00 i4 10 00 13 O 2e 02 C3 b6 280 13* OO CU 00 72 27 OU 00 2 34 26 CO CO 64 62 140 07 00 00 OC 13 00 00 1 2C 02 01 72 271 133 25 00 00 19 56 CO 00 4 65 65 Cl C2 51 216 U 4 00 00 00 84 15 00 00 4 29 44 NORTH ANOMALY S E E P A G E S E D I M E N T 5 6 0 1 0 1 0 9 0 0 0 6 2 6 1 6 5 3 1 0 2 04 0 1 0 1 0 6 0 0 00 69 145 1 1 8 C3 CO OC 2 7 0 9 00 6 0 2 5 4 104 3 3 0 4 C6 2 7 0 6 03 21 7 9 5 77 4 0 0 0 0 0 3 2 13 1 4 0 0 STREAM D R A I N I N G PORTNOY ZONE 1663 1675 1687 1699 PPM JC cu CL P R O P O R T I O N OF C O P P E R • o PROPORTION OF Z I N C • E X T R A C T E D BY S E Q U E N T I A L p • X E X T R A C T E D BY S E Q U E N T I A L R E A G E N T NUMBER 3 LO REAGENT NUMBER < CC O X CC \£. ce % u CL. 3C % O cu 71 1 2 3 1 5 6 7 o i_> o 1 2 3 1 5 6 7 o «-» O 1_» 32 02 02 59 00 01 04 47 60 01 OT 15 48 00 00 28 33 49 42 00 01 34 00 04 19 94 6b 01 00 OC 15 00 00 64 35 42 46 Cl 02 19 00 06 25 193 75 01 00 00 08 00 00 «0 44 65 01 01 03 36 01 06 53 206 96 00 00 00 08 CO 00 92 50 125 o o P R O P O R T I O N OF IRON g • E X T R A C T E D BY S E Q U E N T I A L P * REAGENT NUMBER a: i/i as . K P R O P O R T I O N OF MANGANESE g E X T R A C T E D B Y S E Q U E N T I A L P R E A G E N T NUMOER £ P R O P O R T I O N OF MOLYBDENUM 5 # E X T R A C T E D BY S E Q U E N T I A L < g M R E A G E N T NUMBER | ~ . 1 2 3 1 5 6 7 00 00 01 48 13 00 36 1210 131 00 00 00 .26 20 00 54 2780 116 00 00 00 10 19 CO 50 3060 105 00 00 00 32 19 00 49 3400 123 1 2 3 1 5 6 7 3 3 C6 C3 72 13 01 00 02 4212 100 08 01 le 27 0* 03 39 309 103 19 12 19 24 04 03 19 685 87 01 OC 14 27 05 03 51 316 90 1 2 3 1 5 6 62 00 00 37 01 00 00 20 121 6C 17 00 00 55 27 01 00 20 91 «.t 21 00 00 44 30 C5 00 25 02 >5 06 00 03 51 37 05 00 25 76 1. O r g a n i c a l l y bound metal 2. 3. Amorphous Mn oxides 4. 5. C r y s t a l l i n e Fe oxides 6. 7. S i l i c a t e r e s i d u e s Exchangeable metal Amorphous Fe oxides Hydrogen p e r o x i d e C o n c e n t r a t i o n * - ' t o t a l ' d e t e r m i n a t i o n by a s e p a r a t e n i t r i c / p e r c h l o r i c e x t r a c t i o n Comparison* - sum of s e q u e n t i a l e x t r a c t i o n v a l u e s / ' t o t a l * d e t e r m i n a t i o n v a l u e X 100 171 b. Other inputs to Capoose Lake Transfer of large quantities of Cu, Zn or Ho from lake banks to the lake-via save erosion i s unlikely, in view of the r e l a t i v e l y low metal concentrations along shore compared to nearshore or basinal lake sediments (Tables XXI and XIX). Sim i l a r l y stream sediments do not contain unusually high l e v e l s of trace elements i n -80 mesh stream sediment s p l i t s (Table XXV) , with the exception of r e l a t i v e l y high levels of Cu associated with Swannell Creek sediment. Cu and Zn contents of s i l t and clay fra c t i o n s of Swannell (ID - 15) and Capoose Creek (ID - 28) samples (Table XXVI) are 2X to 6X greater. Nevertheless, concentrations of these metals i n s i l t and clay f r a c t i o n s are 20 to 50% lower than metal contents of corresponding f r a c t i o n s i n lake sediment adjacent to the South Zone (ID - 167 and 173), but are 2X to 4X greater than values i n the Capoose Creek delta (ID - 748). Seepage sediments contain s i m i l a r l e v e l s of Cu as Swannell Creek i n -80 mesh s p l i t s (Table XXIV). Although seepages and 1 springs are r e l a t i v e l y metal-rich, they enter the lake along the shore opposite from lake sediment anomalies. Distance separating seepages and metal-rich zones within the lake, and r e l a t i v e l y small volumes of seepage inflow, mitigate against subaerial seepages exerting a substantial influence on lake metal values. However complementary water samples are commonly metal-rich (Tables XXVIII and XXVII), and subaqueous groundwater i n f l u x to Capoose Lake i s probably important to anomaly genesis. c. Geochemical dispersion from the Green Lake area Table XXV Trace element content (ppm) of stream sediment around the margin of Capoose Lake, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid digestion STREAM SEOIMENTS AT INFLOW POINTS AROUND CAPOOSE LAKE ID CU HO FE HN PB PPM PPM PPM « PFM PPM FIRST SMALL CREEK EAST CF.CAPOOSE CREEK 2 32 45 4 1.9 367 3 SEEPA6E BETWEEN FUST ANC SECOND SMALL CREEKS EAST OF CAPOOSE CPEEK 4 l&Z 47 9 1.7 664 11 SECOND SHALL CREEK EAST OF CAPOOSE CREEK 6 83 36 IS 1.4 417 0 THIRD SHALL CREEK EAST OF CAPOOSE CREEK e 28 27 5 1.2 250 2 ASAR.CO CREEK SE01M.ENT 10 39 82 7 1.5 524 11 ASARCO CREEK SEDIMENT (DUPLICATE) n 44 103 10 1.8 864 7 I CHATUPA CPEEK SEDIMENT 13 23 36 1 1.0 117 1 SPALL STREAM BETWEEN CHATUPA AND SWAtfWELL CREEKS 15 i z a 4E 6 2.3 606 14 j SWA.NNEIL CREEK SEOIMENT 768 35 80 1 1.2 163 10 i FIRST SEEPAGE WEST OF SWANNELL CREEK 17 134 56 1 2.4 221 11 1 SECOND SEEPAGE WEST CF SWANNELL CREEK IS 49 3e 0 0.3 316 9 [ MAJOR STREAM WEST CF SWANNELL CREEK 21 SE 42 5 2.1 507 4 ! CAPCOSE CREEK OUTFLOW SEDIMENT 23 26 S6 5 1.3 1E3 10 CREEK ENTERING CfFCOSE LAKE FROM SMALL LAKE NEAR CAPOOSE CREEK OUTFLOW 25 16 40 7 2.0 2274 12 CREEK ENTERING CAPOOSE LAKE FROM SfALL LAKE HEAR CAPOOSE CPEEK OUTFLOW 1OU'LICATE) ; 26 i a 35 6 1.7 13C7 3 CAPOOSE CREEK SEDIMENT j 26 29 106 5 2.0 695 8 Table XXVI Trace element content, (ppm) of the -80 mesh, and s i l t and clay fractions of selected stream sediments at the margins of Capoose Lake, and selected lake sediments from within Capoose Lake I ID I b s- it COPPER Z I N C MOLYBDENUM IRON MANGANESE LEAD • D E S C R I P T I O N CF S A K F L E S I T E . SIZE FRACTION A N A L Y S I S J A W Q O J&TOTAL S I L T CLAY TOTAL S I L T C L A Y T O T A L S I L T C L A Y TOTAL S I L T CLAY TOTAL S I L T CLAY TOTAL S I L T C U V • i ^ S ? * ! * * * * PPH PPM PPH PPM PPM PPM P P M P P M PPM 1 PPM PPM P P H PPM PPM P P M ' SkAM>(U,CREEK INFLOW TO CAPOOSE LAKE 13 ! 2 1 11 O i l l i e 119 4 1 8 4 8 64 170 6 0 . 0 . 2 . 30 1 0 . 5 0 0.49 606 131 310 1 4 10 1 2 2 CAPCOSE CHEEK INFLOW 1 0 CAPCOSE LAKE 29 75 7 4 0 14 29 4te 998 106 281 574 5 0. 0 . 2 . 0 0 o . i a 0 . 4 4 695 2 4 S 360 e 36 119 CAPOOSE LAKE• L I N E C . M I 0 0 1 E CF THE LAKE 16T 2 4 5 I t 1 25 161 427 1228 5 9 9 327 956 4 0 1. 2 . 6 . 2 0 0 .14 1 . 0 0 1 1 9 0 0 eao 1 4 4 6 12 19 96 CAPCOSE L A K E . L I N E Ci ADJACENT TO SOUTH ZONE M I N E R A L I Z A T I O N 1 1 3 1 4 9 14 2 39 111 516 i s i a 469 290 4 7 0 2 0 1. 1 . 9 . 9 0 0 . 3 3 0 . 56 1 1 8 9 0 800 784 19 32 « 2 CAPOOSE L A K E . LINE Gf N 6 A I S H 0 R E , SCUTW SI-CUE OF LAKE 239 36 37 » 4 16 70 231 9 3 3 3 1 0 174 931 10 0. 0 . 2 . 0 0 0 . 1 3 0 . 3 3 346 169 3 3 T 13 la 101 CAPCOSE LAKE* L I N E E i BMIN NEAR NORTH SNORE OF LAKE 2 0 1 * 4 4 10 1 3 0 et 272 441 290 161 426 IT 0 . 0 . 3 . 1 0 o . i a 0 . 1 9 1100 240 3 5 9 11 3 2 200 CAPCOSE LAKEi LINE I i CAPOOSE CREEK OELTA . . . . . 741 IT 29 19 9 20 II 26* 244 140 19* 140 5 0 . 0 . 2.30 0.11 0.21 469 241 219 IT T 96 %DIFF = 100 - (%SAND + I SILT + %CLAY + %OM) 174 Table XXVII Comparison of trace element content (ppb) of Capoose, Fish and| Portnoy Lake area stream water I Capoose Lake area Green Lake area Portnoy Camp Threshold 147 21 26 Cu Hean 7 4 4 fiange 2-33 1-8 1-9 Threshold 97 120 19 Zn Hean 8 18 4 Eange 2-28 7-47 1-7 Threshold 10100 2150 6890 Fe Hean 348 56 175 Hange 65- 1870 9-350 28-1090 Threshold 215 165 250 Hn Hean 6 12 8 Bange 1-34 ' 3-44 2-46 Threshold 1 ND 130 Ho Hean 1 ND 5 ' Hange ND 1-25 •Threshold 7.51 7.12 7.62 pH -Threshold 5.64 3.11 5.50 Hean 6.57 5.12 6.56 Range 6.11-7.04 4.12-6. 12 6.03-7.09 Number of samples 35 88 23 ND - not detected mean - calculated for a lognormal d i s t r i b u t i o n for Cu, Zn, Fe, Mn, and Mo data; and a normal d i s t r i b u t i o n for pH data range - lognormal (or normal) mean + 1 standard deviation +threshold - ^ (mean + 2 standard deviation i n t e r v a l s ) -threshold - <(mean - 2 standard deviation i n t e r v a l s ) Table XXVIII Trace element content (ppb) °f seepage water around the margin of Capoose Lake ID Cu ppb Zn ppb Bo ppb f e ppb Hn ppb pH 3 39 18 0 767 1*12 7.0 16 14 13 0 1S38 26 6.3 18 c 8 0 1898 9 6.4 176 i . Introduction At Green Lake, Lines 3 and 4 cross numerous exposures of volcanic outcrop (Figs 29 and 30) which are rapidly disintegrating to form a r e s i d u a l - l i k e s o i l . Overburden cover i s r e l a t i v e l y thin and s o i l formation poor as a conseguence of s o l i f l u c t i o n . At lower elevations near Capoose Creek, bedrock i s almost t o t a l l y concealed beneath thick g l a c i a l and c o l l u v i a l deposits. Geochemical anomalies are recognized i n both environments. In the north, Cu - Zn - Ag and Cu - Ag enrichments along narrow zones p a r a l l e l to Capoose Creek are associated with numerous seepages (Fig 22). To the south, Pb -Zn - Cu - Ag enhancement i s associated with talus deposits near the summit of Fawnie Nose. i i . Pb - Zn - Cu - Ag anomaly The Pb - Zn - Cu - Ag anomaly (Figs 37 to 40) represents the largest Pb-rich zone (Fig 26), exhibiting greatest Pb (1200 ppm; Fig 29) and Zn (700 ppm) l e v e l s , encountered i n the Capoose Lake watershed. In addition, Cu (300 ppm) and Ag (7 ppm) are also at regionally anomalous l e v e l s . Trace metal concentrations i n the •A', *Bt and *CI horizons are nearly i d e n t i c a l to each other (Table XXIX). However by comparison to trace element l e v e l s i n North Anomaly s o i l s , only Cu, Zn, Fe and Mo impoverishment i n the ,L-H I, Cu enrichment i n the 'Bg', and Fe enrichment i n the •Bf 1 are s i m i l a r . Proximity of the anomaly to galena-bearing outcrop (Nahring, 1971) and i t s association with prograding t a l u s cones suggests base metals accumulate by mechanical processes 177 F I G U R E 3 7 A : G R E E N L A K E A N O M A L Y LEAD (ppm) IN STREAM SEDIMENTS, "80. MESH FRACTION GEOCHEMICAL LEGEND TOPOGRAPHIC LEGEND -4700- CONTOUR INTERVAL 100 FEET (31m) CREEKS LOCAL GRID COORDINATES • TRAVERSE LINES *• SAMPLE LOCATION less than 18 ppm 18 _ 55 ppm 55 _ 175 ppm more lhan 175 ppm 4 0 0 0 FEET 1 0 0 0 M Figures 37 to 41: Coded intervals represent: <(x); (x) to (x+<r); (x+<r) to (x+2o-j ; and >(x+2<r) 178 F I G U R E 3 7 B : G R E E N L A K E A N O M A L Y LEAD (ppm) IN TOP OF THE 'B' SQL HORIZON, -80 ^ S H FRACTION TOPOGRAPHIC LEGEND -4700- CONTOUR INTERVAL 100 FEET (31m) CREEKS -. LOCAL GRID COORDINATES — — TRAVERSE LINES SAMPLE LOCATION GEOCHEMICAL LEGEND . less thon 22 ppm . 22 - 75 ppm • 75 - ,260 ppm . -O more' thdn 260 ppm 4 0 0 0 F E E T 1 0 0 0 M J FIGURE 38A: GREEN LAKE ANOMALY ZINC (ppb) IN STREAM WATER • TOPOGRAPHIC LEGEND -4700- CONTOUR INTERVAL 100 FEET (31m) CREEKS LOCAL GRID COORDINATES TRAVERSE LINES SAMPLE LOCATION .. GEOCHEMICAL LEGEND *a. less than 18 ppb • 18' - 47 ppb © 48 - 120 ppb . © more than 120 ppb 4 0 0 0 FEET 1 0 0 0 M 180 F I G U R E 3 8 E : G R E E N L A K E A N O M A L Y Z I N C (ppm) IN S T R E A M SEDIMENTS, " 8 0 M E S H F R A C T I O N T O P O G R A P H I C L E G E N D -4700- CONTOUR INTERVAL 100 FEET (31m) — CREEKS LOCAL GRID COORDINATES — - TRAVERSE LINES - SAMPLE LOCATION GEOCHEMICAL L E G E N D . less than 80 ppm # 80 " 240 ppm « 240 - 7 00 ppm © more than 7 0 0 P P m 4 0 0 0 FEET 1 0 0 0 M 181 F I G U R E 3 8 C : G R E E N L A K E A N O M A L Y ZINC (ppm) IN TOP OF THE 'B' SOIL HORIZON, -80 MESH FRACTION TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND -4700- CONTOUR INTERVAL 100' FEET (31m) • less than 80 ppm CREEKS . 80 - 185 ppm LOCAL GRID COORDINATES o 185 - 420 ppm ' - — — T R A V E R S E LINES © more than 420 ppm - S A M P L E LOCATION | 4000 F E E T 1 i' looo M 1 182 FIGURE. 3 9 A : GREEN LAKE ANOMALY COPPER (ppb) IN STREAM WATER TOPOGRAPHIC LEGEND -4700- CONTOUR INTERVAL 100 FEET (31mJ CREEKS LOCAL GRID COORDINATES TRAVERSE LINES - SAMPLE LOCATION GEOCHEMICAL LEGEND less than 4 ppb • 4 - 8 ppb © 9 - 21 ppb © more than 21 ppb 4 0 0 0 FEET 1 0 0 0 M J 183 . F I G U R E : 3 9 B : G R E E N L A K E A N O M A L Y COPPER (ppm) IN STREAM SEDIMENTS, -80 MESH FRACTION , TOPOGRAPHIC LEGEND N -4700- CONTOUR INTERVAL 100 FEET (31m) CREEKS LOCAL' GRID COORDINATES TRAVERSE LINES SAMPLE LOCATION GEOCHEMICAL 'LEGEND - less than 50 ppm . 50-- 110 ppm O 110 " 240 ppm © more than 240 ppm 4 0 0 0 FEET 1 0 0 0 M I 184 , F I G U R E 3 9 C : GREEN L A K E A N O M A L Y jCOPPER (ppm) IN TOP OF T H E 'B' SOIL HORIZON, "80 MESH FRACTION TOPOGRAPHIC LEGEND •'" GEOCHEMICAL LEGEND -4700- CONTOUR INTERVAL 100 FEET (31m J . less than 35 ppm CREEKS . 35 - 65 ppm LOCAL GRID COORDINATES © 65 - 120 ppm TRAVERSE LINES © more than 120 ppm \ - SAMPLE LOCATION . 4 0 0 0 FEET j i 1 1 0 0 0 M 185 F I G U R E . 4 0 A : G R E E N L A K E A N O M A L Y SILVER (ppm) IN STREAM SEDIMENTS, -80 MESH FRACTION TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND -4700- CONTOUR INTERVAL I0O FEET (31m) . less than 0 83 pprn CREEKS . 083 - 212 ppm , LOCAL GRID COORDINATES e 212 - 5-46 ppm ' - - — T R A V E R S E LINES © more than 5-46 ppm SAMPLE LOCATION . 4 0 0 0 FEET 1 1 1 0 0 0 M 1 186 F I G U R E 4 0 B : G R E E N L A K E A N O M A L Y SILVER (ppm) IN TOP OF THE ' ' " ~** ~ TOPOGRAPHIC LEGEND -4700- CONTOUR INTERVAL 100 FEET • : CREEKS LOCAL GRID COORDINATES TRAVERSE LINES *• SAMPLE LOCATION 'B' SOIL HORIZON, -80 MESH FRACTION (31m) GEOCHEMICAL LEGEND . less than 0-66 ppm • 0 66 - 181 ppm e 181 - 275 ppm :•, O more than 2-75 ppm 4 0 0 0 FEET  1 0 0 0 M T J 187 F I G U R E 4 1 : G R E E N L A K E A N O M A L Y p H O F S T R E A M W A T E R GEOCHEMICAL LEGEND TOPOGRAPHIC LEGEND -4700- C O N T O U R INTERVAL 100 F E E T I P 1 1 1 1 J C R E E K S L O C A L GRID C O O R D I N A T E S — T R A V E R S E L I N E S - S A M P L E L O C A T I O N O less fhan 3 11 O 311 - 412 • 413 - 612 © 613 - 7 12 © more than 712 4 0 0 0 FEET 1 0 0 0 M 1 Table XXIX Trace element content (ppm) of d i f f e r e n t s o i l horizons. Green Lake area, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c a c i d attack L-H horiton horison' Top of B Bf horizon Bm horizon Bg horieon C horizon Cu Threshold Mean Ran go • 26 15 12 - 20 125 28 13 - 60 120 35 19 - 65 75 31 20 i 48 J 130 1 8 - 6 5 210 60 3 4 - 1 1 5 145 34 16 - 70 Zn Threshold Mean Range 320 50 20 - 125 330 65 29 - 145 420 80 35 - 185 135 60 33 7 105 580 100 41 - 235 120 65 4 6 - 9 0 380 80 35 - 170 Fa i Threshold Ms an Jw.r.go 2.7 1.5 0.83 - 1.8 4.6 2.1 1.5 - 3.2 6.1 2.8 1.9 - 4.1 5.5 3.0 2.2 4.1 5.8 2.8 1.9 - 4.0 11.2 2.1 0.91 - 4.9 6.1 2.7 1.8 - 4.1 Mn ThMshold Mar.n 3400 190 45 - 810 2700 240 70 - 800 1200 220 95 - 520 930 160 65 - 390 1250 260 120 - 570 480 180 110 - 290 1200 280 130 - 580 Pb Threshold Mes.n Range 55 16 8.6 - 30 195 23.. 8.1 - 75 260 22 6.6 - 75 ' 145 13 6.2 - 50 350 26 7.2 - 95 47 15 8.5 - 27 390 19 4.0 - 85 Mo Threshold Ma an Range 5.0 1.5 0.8 - 2.8 11 3.1 1,7 - 5.8 13 3.5 1.8 - 6.7 10 3.3 1.9 - 5.8 14 . 3.5 1.7 - 7.1 . 11 3.2 1.7 - 6.1 . 12 3.4 1.8 - 6.3 Ag Threshold Ksan . Rango 2.46 0.40 0.16 - 0.99 5.83 0.63 0.31 - 2.20 2.75 0.66 0.24 - 1,81 3.40 0.57 0.23 -1 . 3 9 2.93 0.70 0.24 - 2.09 3.50 0.70 0.32 - 1.57 4.39 0.77 ,, 0.32 - 1.84 Yxsl s&ir er of pies 29 52 175 52 110 8 60 Xuisbar of sinplos - As 7 19 146 42 92 9 37 mean - calculated for a lognormal d i s t r i b u t i o n range - lognormal mean + 1 standard deviation threshold - >(mean + 2 standard deviation i n t e r v a l s ) 189 (Hoffman, 1972; 1976). Nevertheless hydromorphic dispersion may be important over r e s t r i c t e d areas, as indicated by Pb enhancement i n seepages along Anomaly Creek above Line 4 (Fig 37). Unfortunately, Pb was excluded from the seguential extraction study. Zn, however, appears r e l a t i v e l y insoluble i n p r o f i l e s 925 to 927 and 916 to 919, i n view of the 80 to 90% of the ' t o t a l * metal content i n the s i l i c a t e residue (Table XXII). However only 50 to 60$ of the t o t a l Zn i s accounted f o r , suggesting the c r y s t a l l i n e Fe oxide f r a c t i o n may also control Zn l e v e l s . Enhanced Mn values are also residue-related whereas by contrast, Cu enrichment (ID - 925 to 927) r e f l e c t s scavenging by c r y s t a l l i n e (37$) and amorphous (27$) Fe oxides. Apart from enhanced Pb and Zn values along Line 3, the anomaly i s distinguished hy notable enrichment of Mo to 35 ppm (Table XXIX) along Line 4. Mo content of the anomalous p r o f i l e (ID 362 to 367) i s associated with Fe oxides, and i s not accompanied by enrichment of other elements. Importance of mineral occurrences i n the Fawnie Hange on Cu and Mo accumulation i n Capoose Lake i s r e l a t i v e l y minor compared to the influence of the large number of Cu and Mo anomalies near the lake (Fig 26). By comparison, Pb and Zn enrichment appears to r e f l e c t occurrence of Pb and Zn minerals*in the mountains 8 to 13 km from Capoose Lake. Anomalous dispersion t r a i n s for these elements, and Cu and Ag, are common near Green Lake. The anomalous Pb, Zn, Cu and Ag dispersion along Anomaly Creek i s the most prominent of the area. Cu concentrations decline most rapi d l y , and metal l e v e l s diminish to background values 1.5 km downslope of the s o i l anomaly. Zn and Ag dispersion t r a i n s are 190 s l i g h t l y longer. The Pb dispersion t r a i n i s the longest, and contents exceeding the regional threshold extend to Capoose lake. Though decay to 1/10 of values near the headwaters of Anomaly Creek occurs before reaching the confluence of Anomaly and Capoose Creeks (20 ppm), and values diminish to 8 to 16 ppm l e v e l s near Capoose Lake (unpublished data, Rio Tinto), t h i s s t i l l represents concentrations well above the regional threshold. Stream sediment sequential extraction data are s i m i l a r to s o i l s i n that Zn enhancement i s primarily associated with the s i l i c a t e residue. On comparison of sample 342 and sample 893, 360 m downslope (Table XXIV), the 2X increase i n ' t o t a l ' Zn and Mn l e v e l s to 560 and 1360 ppm, respectively, apparently r e f l e c t s increased scavenging by amorphous (and c r y s t a l l i n e for Zn?) Fe oxides. This implies a change i n the dominent mechanism of dispersion from mechanical near the mountain summit to hydromorphic downstream. However Mn i s more l a b i l e i n stream sediments than i n s o i l s . Values exceeding 1000 ppm ' t o t a l ' are primarily s o l u b i l i z e d by hydroxylamine hydrochloride and i n t h i s respect are s i m i l a r to samples 620 and 632 of Swannell Creek. Retention of Cu and Mo by amorphous Fe oxides i s also s i m i l a r to the manner by which these elements are held in Swannell Creek sediment. i i i . Cu - Zn - Ag anomaly The Cu - Zn - Ag anomaly (Fig 22) l i e s near the base of an 1100 m long slope i n a region of i s o l a t e d exposures of granodiorite. The metal-rich zone also coincides with a 191 prominent seepage zone and, i n vies of Cu and Ag enrichment i n associated, s l i g h t l y a c i d i c (pH 4.1 to 6.1) seepage water and sediment (Figs 39 and 40), probably r e f l e c t s deposition of metals from groundwater. However Cu accumulation to a maximum of 230 ppm* i s s l i g h t l y lower than the previously described anomaly. Mo contents of les s than 8 ppm are notably poorer than i s commonly observed i n s o i l s overlying granodiorite. This probably r e f l e c t s limited Mo s o l u b i l i t y i n ac i d i c environments and/or absence of a source of metal upslope. Sequential extraction data only partly confirm a hydromorphic o r i g i n for t h i s anomaly. Seepage sample 1037 (Table XXIV) indicates most of the Cu accumulates with organic matter. This contrasts to data from p r o f i l e 1023 to 1027 upslope of the seepage zone which indicates over 50% of the metal i s residue-bound, the remaining f r a c t i o n associated with one or the other Fe oxide phases. S i m i l a r l y , Capoose Creek sediment (ID - 1033) appears to concentrate Cu with i t s Fe oxide components. In both l a t t e r cases, however, " t o t a l 1 Cu values are only s l i g h t l y enhanced over background (Fig 30 and Table XXIX). i v . Cu - Ag anomaly Line 5 investigates Cu enhancement i n thick g l a c i a l overburden underlain by granodiorite. Anomalous zones coincide with seepages marking a topographic i n f l e c t i o n near Capoose Creek. Though seepage zone development i s not as outstanding as at the Cu - Zn - Ag anomaly, metal accumulation probably proceeds i n an analogous fashion by deposition from goundwater. 192 Within s o i l p r o f i l e s (Pig 30),-Cu, Zn, Pb and Mo l e v e l s are enhanced i n *Bf» and »C* horizons whereas by contrast, the 'L-H* i s notably metal-deficient. Contrast of values within the same horizon across the anomaly i s low, and Cu values of 100 ppm i n the •Bf 1 and Zn contents of 120 ppm i n 'Bf 1 and •C horizon samples are considered i n d i c a t i v e of anomalous conditions. Mo and Pb values vary from the detection l i m i t to 8, and from 5 to 40 ppm# respectively, and represent background. Mechanical erosion of metal-rich s o i l s by streams does not lead to drainage Cu and Zn anomalies. However drainage geochemistry i s i n t e r e s t i n g because Ag contents i n streams average 2 ppm over 500 m, l o c a l l y exceeding 25 ppm. d. Trace metal d i s t r i b u t i o n i n lake sediment Capoose Lake sediment can be divided on the basis of sample texture and proximity of the sampling s i t e to inflowing streams or shore. Nearshore and basinal samples can be further divided into eastern and western groupings r e l a t i v e to the position of the Capoose Creek d e l t a . Nearshore sediment i n the west contains, on the average, 2X to 3X more Cu> Zn, Mo, Fe, Mn (up to 8X) , Pb and organic matter than i n the east (Table XIX). Concentrations of these elements i n the delta are s i m i l a r for Pb and Fe, and lower i n Cu, Zn, Mo and Mn contents than average nearshore samples, but are si m i l a r to values along the eastern shoreline. Comparison of the trace element content of Capoose and Swannell Creeks (ID - 28 and 15, r e s p e c t i v e l y ) , and an adjoining sample of the delta (ID - 748) indicates the l a t t e r contains 1 9 3 more Cu, Zn and Pb than Capoose Creek, the main contributor of d e l t a i c sediment. However l e v e l s of Mo, Fe and Hn are si m i l a r (Table XXVI). By comparison, Swannell Creek sediment i s r e l a t i v e l y Cu-richi Although inputs from Swannell Creek may explain the Cu-rich character of the delta compared to Capoose Creek, Zn content i s not s u f f i c i e n t l y high to account f o r a corresponding Zn enhancement. Data from s i l t and cla y - s i z e d f r a c t i o n s indicate that Cu and Zn content of Capoose Creek, and Cu content of Swannell'Creek, are enriched by 10X to 20X values i n the -80 mesh f r a c t i o n (Table XXVI). Moreover, Cu content of s i l t and clay from Capoose and Swannell Creeks i s enriched 1.2X to 4.OX values i n corresponding s p l i t s of a sample from the delta. S i m i l a r l y , Capoose Creek s i l t and clay contains 1.7X and 4.OX more Zn than corresponding fr a c t i o n s of the delta sample. Failur e of Cu and Zn-rich s i l t and clay associated with inflowing streams to accumulate i n the delta suggests: d i l u t i o n by barren inputs or longshore d r i f t , s o l u b i l i z a t i o n of these elements after sediment deposition, or transport of s i l t and clay suspensions towards the middle of the lake. The l a t t e r explanation might*provide a mechanism for transferring metal-r i c h s i l t and clay to the middle of the lake, to accumulate i n hy d r a u l i c a l l y - i n a c t i v e portions of the lake floor. Transport of metal-rich s i l t and clay by Capoose Creek currents i s i n d i r e c t l y indicated by enhanced Cu and Zn contents i n lake water (Figs 31 and 32) of up to 35 ppb and 127 ppb (lake averages are 4 and 14 ppb, respectively; Table XXX) i n an elongated zone along the presumed d i r e c t i o n of Capoose Creek flow across the d e l t a . However because u n f i l t e r e d water samples contain 66% more Cu and 194 Zn than f i l t e r e d samples (Table X), enhanced l e v e l s probably r e f l e c t leaching of metals from suspended fines following f i e l d a c i d i f i c a t i o n of water samples. Trace element content of sediment of other streams i s available only for -80 mesh s p l i t s . Average values are si m i l a r to those of nearshore sediment (Tables XXIII and XIX), with larger streams having the lowest concentrations (Table XXV). Although metal l e v e l s of the Chatupa Creek delta are unknown because of sampling d i f f i c u l t i e s , metal content of sediments from Chatupa (ID - 13) and Asarco (ID - 10 and 11) Creeks i s low. By contrast, Cu leve l s of 120 to 180 ppm i n spring sediments (ID - 4, 15 and 17) are higher than stream values. Points of spring inflow* however, l i e opposite to lake base metal anomalies, and are unlikely to influence greatly metal accumulation along the lake f l o o r . Nevertheless metal-rich springs indicate groundwater of the region can contain substantial amounts of metal which might be deposited under favourable conditions. More s t r i k i n g than differences i n metal content between di f f e r e n t classes of c l a s t i c sediment i s the 3X to 12X enhancement i n l e v e l s associated with f i n e l y - d i v i d e d oozes near the middle of the lake compared to nearshore or d e l t a i c values. Magnitude of the difference depends on element and sample position i n the lake. Average values i n the west are 1.5X to 2.0X higher than those in the east (Table XIX) . Although metal enhancement t y p i f i e s sediment from the middle of the lake, values are by no means uniform i n t h i s environment. Cu, Zn, Mo, Fe and Mn appear to accumulate p r e f e r e n t i a l l y along 2 zones. TABLE XXX Comparison of trace element content (ppb) of Capoose, Fish and Portnoy Lake lake water Capoose lake F i s h Lake Portnoy Lake Threshold 16 6 4 Co Mean 4 2 1 fiange 1-6 1-3 1-2 Threshold 63 12 13 Zn Hean 14 7 9 fiange 7-30 5-9 7-11 Threshold 14200 1320 130 Fe Hean 416 340 60 fiange 71-2430 173-670 41-88 Threshold 4270 69 17 tin Hean 64 7 13 fiange 8-520 2-23 11-15 Threshold 7 3 ND . Ho Hean 1 1 ND fiange 1-3 1-2 ND •Threshold 6. 94 7.01 7.22 pH -Threshold 6.48 6.39 6.90 Hean 6.71 6.69 7.06 Range 6.60-6.82 6.52-6.85 6 . 9 8 - 7 . Number of samples 184 24 12 ND - n o t d e t e c t e d mean - c a l c u l a t e d f o r a l o g n o r m a l d i s t r i b u t i o n f o r Cu, Zn, Fe, Mn, and Mo d a t a ; and a normal j d i s t r i b u t i o n f o r pH d a t a range - l o g n o r m a l ( o r normal) mean + 1 s t a n d a r d d e v i a t i o n :+threshold - ^ (mean + 2 s t a n d a r d d e v i a t i o n i n t e r v a l s ) i - t h r e s h o l d - <C (mean - 2 s t a n d a r d d e v i a t i o n i n t e r v a l s ) 196 each approximately 100 m wide, p a r a l l e l to the north and south shores of the lake. Metal-rich zones commonly l i e 50 to 150 m offshore i n 15 to 25 m of water, and tend to coincide with an abrupt break i n the nearshore slope (Figs 42 to 51). However i t must be stressed that trace metal d i s t r i b u t i o n s are complex, and the foregoing description i s a s i m p l i f i c a t i o n of actual d i s t r i b u t i o n s . Trace metal accumulation at topographic i n f l e c t i o n s i s best i l l u s t r a t e d by Mn data along Line K (Fig 50). Values are r e l a t i v e l y low i n nearshore samples and increase s u b s t a n t i a l l y going to deeper water u n t i l a maximum value i s reached near the break i n slope. Concentrations then decrease markedly, so that sediment near the middle of the lake might contain only 20% as much Hn as peak values, though l e v e l s are s t i l l much higher than i n nearshore sediment. This pattern i s repeated on the other side of the lake. This 'double peak di s t r i b u t i o n * or double maximum d i s t r i b u t i o n ' i s a common feature among Cu, Zn, Fe, Mn and Mo data f o r water and/or sediment. Only Pb le v e l s fluctuate apparently randomly, between 2 and 29 ppm (average 12 ppm; Fig 52). Values are lowest nearshore and near the South Zone whereas highest contents l i e nearshore and northwest of the Capoose Creek delta. Position of Cu, Zn and Mo-rich zones r e l a t i v e to topographic i n f l e c t i o n s varies with element and other f a c t o r s . Greatest concentrations of 160 ppm Cu, 600 ppm Zn and 60 ppm Mo l i e offshore of the South Zone. However maximum concentrations of these elements within other metal-rich regions of the lake are 20 to 50% lower. Zn and Mo anomalies usually coincide with rt * 0.0 • 6.1 IA IE •12.2 UJ r •18.3 i •21.1 u i ra •30,5 DISTANCE FROM SOUTH SHORE Cu IN LAKE WATER • LESS THAU 1 PPB • 4 TO 6 PPB • 7 TO 16 PPB B MORE THAN 16 PPB L E G E Cu DISTANCE FROM SOUTH SHORE H D T] 500 FEET 0 152 M DISTANCE FROM SOUTH SHORE. 0 500 FEET 0 152 H DISTANCE FROM SOUTH SHORE . "0 500 0 152 DISTANCE FROM SOUTH SHORE FEET M . IN LAKE SEDIMENT • LESS THAN 70 PPH • 70 TO 135 PPH 9 136 TO 245 PPH 9 MORE THAN 215 P P H ZN L E IN LAKE WATER LESS THAN 14 PPB 14 TO 30 PPB 31 TO 63 PPB MORE THAN 63 PPB G E N U ZN IN LAKE SEDIMENT • LESS THAN 250 PPH • 250 TO 480 PPH • 481 TO 930 PPH • MORE THAN 930 PPH Mo L E IN LAKE WATER LESS THAN 1 PPB 1 TO 3 PPB 4 TO 7 P P B MORE THAN 7 P P B 0 500 FEET, 0 152 H DISTANCE FROM SOUTH SHORE G E N D Mo IN LAKE SEDIMENT • LESS THAN 11 PPH • 11 TO 30 PPH • 31 TO 83 PPM • MORE THAN 88 P P H r — ; — \ | i —r~ 1 1 i U4-1 1 1 ! 0 500 FEET 0 152 « . DISTANCE FROM SOUTH SHORE 0 500 FEET 0 . 152 M DISTANCE FROM SOUTH SHORE 0 500 FEET 0 152 M DISTANCE FROM SOUTH SHORE 0 500 FEET 0 152 M DISTANCE FROM SOUTH SHORE Figures 42 to 52: Coded in t e r v a l s represent: (x) to (x+<r), (x+cr) tO (X+20, Xx+2<r) L E G E N D FE IN LAKE WATER FE IN LAKE SEDIMENT • LESS THAU 416 PPB • LESS THAN 3.2Z • 416 TO 2430 PPD • 3.2 To 6.0Z a 2.4 TO 14.2 PPH • 6.1 TO 11.3Z S H O R E THAN 14.2 PPMCMORE THAN 11.3X L E G E N D MN IN LAKE WATER • LESS THAN 64 PPB • 64 TO 520 PPB B 0.52 TO 4.27 PPH MN IN LAKE SEDIHENT • LESS THAN 1300 PPH • 1300 TO 5000 PPM • 5001 TO 19100 PPH I MORE THAN 4.27 P P H « MORE THAN 19100 PPH F I G U R E 4 2 : T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D L A K E W A T E R ( P P B ) A L O N G L I N E S B A N D A / C A P O O S E L A K E ^1 is i 5 60-Q_ U J ° 80« loov 1 l 500 152 1 0 0 0 3 0 5 1500 FEET 457 H 1 »0.0 • 6.1 L12.2 ( i > K A J * •18.3 .Ob h i 1 / 1 n \S i c ^ > A H .1 1 ft u 1 1 -1 • | 0 0 500 152 lfloc 30E 1*00 FEET -457 H 0 0 5S0 1( 152 I iOO 15*00 FEET 105 457 M DISTANCE FROM SOUTH SHORE DISTANCE FROM SOUTH SHORE DISTANCE FROM SOUTH SHORE L E G E N D Cu IN LAKE WATER • LESS THAN 4 PPB • 4 TO 5 PPB 8 7 TO 16 PPB 13 MORE THAN 16 PPB Cu IN LAKE SEDIMENT ZN IN LAKE WATER . LESS THAN 70 PPM • LESS THAN 14 PPB • 70 TO 135 PPM 0 136 TO 245 PPM 9 MORE THAN 245 PPM • 14 TO 30 PPB • 31 TO 63 PPB • MORE THAN 6 3 PPB L E G E N D ZN IN LAKE SEDIMENT MO IN LAKE WATER T LESS THAN 250 PPM * LESS THAN 1 PPB • 250 TO 480 PPM • 1 TO 3 PPB • 481 TO 930 PPM B 4 TO 7 PPB O MORE THAN 930 PPM H MORE THAN 7 PPB L E G E N D Mo IN LAKE SEDIMENT • LESS THAN 11 PPM • 11 TO 30 PPH • 31 TO 88 PPH Q MORE THAN 88 PPH 500 152 DISTANCE FROM SOUTH SHORE 1500 FEET 457 M DISTANCE FROM SOUTH SHORE L E G E N D FE' IN LAKE WATER FE IN LAKE SEDIMENT • LESS THAN 416 PPB • LESS THAN 3.2Z • 416 TO 2430 PPB • 3.2 TO 6.0Z • 2.4 TO 14.2 PPH © 6.1 TO 11.31 SHORE THAN 14.2 PPM ©MORE THAN 11.31 L E G E N D MN IN LAKE WATER ' MN IN LAKE SEDIMENT • LESS THAN 64 PPB • LESS THAN 1300 PPM • 64 TO 520 PPB • 1300 TO 5000 PPM B 0.52 TO 4.27 PPM • 5001 TO 19100 PPM 8 MORE THAN 4.27 PPH* MORE THAN 19100 PPH F I G U R E 4 3 : T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D L A K E W A T E R ( P P B ) A L O N G L I N E C , C A P O O S E L A K E 1000 305 1500 FEET 157 M i D r f • i | V' 11 r I = DISTANCE FROM SOUTH SHORE 5u0 10*00. 1*00 FEET 152 305 157 M DISTANCE FROM SOUTH SHORE 15*00 FEET 157 H DISTANCE FROM SOUTH SHORE L E G E N D Cu IN LAKE HATER • LESS THAN 1 PPB • 1 TO 6 PPB B 7 TO 16 PPB S3 MORE THAN 16 PPB L E G E N D Cu IN LAKE SEDIMENT ZN IN LAKE WATER ZN IN LAKE SEDIMENT MO IN LAKE WATER • LESS THAN 70 PPM 0 LESS THAN 11 PPB • LESS THAN 250 PPM e> LESS THAN 1 PPB • 11 TO 30 PPB • 250 TO 180 PPM • 1 TO 3 PPB B 31 TO 63 PPB e 181 TO 930 PPM B n TO 7 PPB B MORE THAN 63 PPB 9 MORE THAN 930 PPM ffl MORE THAN 7 PPB • 70 TO 135 PPM • 136 TO 215 PPM Q MORE THAN 215 PPM L E G E N D Mo IN LAKE SEDIMENT • LESS THAN 11 PPM • 11 TO 30 PPM • 31 TO 88 PPM • MORE THAN 88 PPH 1500 FEET 157 H t \ \ r--i •N /I 1 E 1 3 ; 1 n 1 ' 1 50*0 152 1000 305 1500 FEET 157 M * 0.0 • 6.1 g •12.2 g •18.3 g •21.1 jj •30.5 DISTANCE FROH SOUTH SHORE DISTANCE FROM SOUTH SHORE. L E G E N D L E G E N D FE' IN LAKE WATER FE IN LAKE SEDIMENT MII IN LAKE WATER ' MN IN LAKE SEDIMENT • LESS THAN 116 PPB • LESS THAN 3.2* • LESS THAN 61 PPB • LESS THAN 1300 PPH • 116 TO 2130 PPB • 3.2 TO 6.0Z • 61 TO 520 PPB • 1300 TO 5000 PPH B 2.1 TO 11.2 PPH • 6.1 TO 11.3* B 0.52 TO 1.27 PPH • 5001 TO 19100 PPH QMORE THAN 11.2 PPM ©MORE THAN 11.3Z EJ MORE THAN 1.27 PPM® MORE THAN 19100 PPH F I G U R E T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D L A K E W A T E R ( P P B ) A L O N G L I N E D , C A P O O S E L A K E to •0.0 DISTANCE FROM SOUTH SHORE DISTANCE FROM SOUTH SHORE sBo 10*00 15*00 FEET 152 305 H57 H DISTANCE FROM SOUTH SHORE L E G E N D L E G E N D L E G E N D Cu IN LAKE WATER Cu IN LAKE SEDIMENT ZN IN LAKE WATER ZN IN LAKE SEDIMENT MO IN LAKE WATER MO IN LAKE SEDIMENT • LESS THAU 1 PPB t LESS THAN 70 PPM • LESS THAU 11 PPB • LESS THAN 250 PPM a LESS THAN 1 PPB o 1 TO 6 PPB • 70 TO 135 PPM "11 TO 30 PPB • 250 TO 180 PPM » 1 TO 3 PPB 0 7 TO 16 PPB • 136 TO 215 PPH • 31 TO 63 PPB • 181 TO 930 PPM • 1 TO 7 PPB 1 MORE THAN 16 PPB 0 MORE THAN 215 PPH E MORE THAN 63 PPB 9 MORE THAN 930 PPH 1 MORE THAN 7 PPB • LESS THAN 11 PPH • 11 TO 30 PPM © 31 TO 88 PPH • HORE THAN 88 PPH ; • 0* 20-U J s 10. £ 60«| O. LLI ° 80" loot 1 J 7 - T v -j, t. J -ft 2 err; r i i 1 — ft- U P — - - - - - -500 152 1000 305 1500 FEET 157 M 1500 FEET 157 M C O N T O U R S R E P R E S E N T T E M P E R A T U R E I S O T H E R M S ; 6° , 8 ° , A N D 1 0 ° I S O T H E R M S A R E L A B E L L E D DISTANCE FROM SOUTH SHORE DISTANCE FROM SOUTH SHORE L E G E N D L E G E N D FE' IN LAKE WATER FE IN LAKE SEDIMENT MN IN LAKE WATER • MN IN LAKE SEDIMENT • LESS THAN 116 PPB • LESS THAN 3.2Z • LESS THAN 61 PPB • LESS THAN 1300 PPM • 116 TO 2130 PPB • 3.2 TO 6.0Z • 61 TO 520 PPB • 1300 TO 5000 PPH n 2.1 TO 11.2 PPM • 6.1 TO 11.3Z • 0.52 TO 1.27 PPH • 5001 TO 19100 PPM QMORE THAN 11.2 PPH © HORE THAN 11.31 Q MORE THAN 1.27 PPH® MORE THAN 19100 PPH F I G U R E 4 5 : T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D L A K E W A T E R ( P P B ) A L O N G L I N E E , C A P O O S E L A K E o o 0« H 20. U l " 10. i £ 60* a. U J « 80" 1 — j ... - - - - -: -• -3 -i \ ! • -4-7— 500 152 1000 305 1500 FEET 157 M ;5o DISTANCE FROM SOUTH SHORE 152 305 DISTANCE FROM SOUTH SHORE 500 FEET 157 H 50*0 10*00 15*00 FEET 152 305 157 M DISTANCE FROM SOUTH SHORE L E G E N D Cu IN LAKE WATER • LESS THAU 1 PPB • 1 TO 6 PPB 8 7 TO 16 PPB B HORE THAN 16 PPB L E G E N D Cu IN LAKE SEDIMENT ZN IN LAKE HATER ZN IN LAKE SEDIMENT NO IN LAKE WATER T LESS THAN 70 PPM • LESS THAN 11 PPB • LESS THAN 250 PPH A LESS THAN 1 PPB • 70 TO 135 PPH • 11 TO 30 PPB • 250 TO 180 PPM » 1 TO 3 PPB • 136 TO 215 PPM • 31 TO 63 PPB • 181 TO 930 PPH B 1 TO 7 PPB % MORE THAN 215 PPH B MORE THAN 63 PPB • MORE THAN 930 PPM g MORE THAN 7 PPB L E G E N D Ho IN LAKE SEDIMENT • LESS THAN 11 PPM • 11 TO 30 PPM • 31 TO 88 PPH t HORE THAN 88 PPH »-U J 20/ U J u. 1 10.-X \- 60«-a. Q 80.-loo; 500 152 1000 305 I •1 7 - - j I t— -4-« c ~ ! i - V V r- D 1 « 1 | 1500 FEET 157 H 152 I V \ j f • / » 1 / f « \ 5 f I H P * > = * - f c r • 0.0 • 6.1 •12.2 •18.3 •21.1 305 157 H DISTANCE FROM SOUTH SHORE DISTANCE FROM SOUTH SHORE ^•30.5 L E G E N D L E G E N D FE' IN LAKE WATER FE IN LAKE SEDIMENT MM IN LAKE WATER • LESS THAN 116 PPB • LESS THAN 3.2Z » 116 TO 2130 PPB • 3.2 TO 6.0Z • 2.1 TO 11.2 PPH • 6,1 TO 11.3Z S3 MORE THAU 11.2 PPH 9 MORE THAN 11.3Z MN IN LAKE SEDIMENT • LESS THAN 61 PPB • LESS THAN 1300 PPH • 61 TO 520 PPB . • 1300 TO 5000 PPH • 0.52 TO 1.27 PPH 9 5001 TO 19100 PPH 52 HORE THAN 1.27 PPM© MORE THAN 19100 PPM F I G U R E 4 6 : T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D L A K E W A T E R ( P P B ) A L O N G L I N E F , C A P O O S E L A K E o 15*00 FEET 157 M DISTANCE FROM SOUTH SHORE DISTANCE FROM SOUTH SHORE DISTANCE FROM SOUTH SHORE •0.0 L E G E N D L E G E N D L E G E N D Cu IN LAKE'WATER CU IN LAKE SEDIMENT ZN IN LAKE HATER . LESS THAN 1 PPB t LESS THAN 70 PPH " LESS THAN 11 PPB • 1 TO 6 PPB • 70 TO 135 PPH • 11 TO 30 PPB B 7 TO 16 PPB • 136 TO 215 PPM . B 31 TO 63 PPB HMORE THAN 16 PPB O MORE THAN 215 PPH E3 MORE THAN 63 PPB ZN IN LAKE SEDIHENT MO IN LAKE WATER T LESS THAN 250 PPH > LESS THAN 1 PPB • 250 TO 180 PPH * 1 TO 3 PPB • 181 TO 930 PPM B 1| TO 7 PPB • MORE THAN 930 PPH H MORE THAN 7 PPB Flo IN LAKE SEDIMENT • LESS THAN 11 PPH • 11 TO 30 PPH • 31 TO 88 PPM 9 MORE THAN 88 PPH 1500 FEET 157 M DISTANCE FROM SOUTH SHORE DISTANCE FROM SOUTH SHORE L E G E N D FE' IN LAKE WATER FE IN LAKE SEDIMENT • LESS THAN 116 PPB • LESS THAN 3.2Z • 116 TO 2130 PPB • 3.2 TO 6.0Z • 2.1 TO 11.2 PPH • 6.1 TO 11.31 SHORE THAN 11.2 PPH ©MORE THAN 11.31 L E G E N D MN IN LAKE WATER • MN IN LAKE SEDIMENT • LESS THAN 61 PPB • LESS THAN 1300 PPH • 61 TO 520 PPB • 1300 TO 5000 PPH • 0.52 TO 1.27 PPH • 5001 TO 19100 PPH S3 MORE THAN 1.27 PPH© MORE THAN 19100 PPH F I G U R E 4 7 : T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D L A K E W A T E R ( P P B ) A L O N G L I N E G , C A P O O S E L A K E . o ' 0 500 FEET 0 1 52 H DISTANCE FROH SOUTH SHORE L E Cu IN LAKE HATER • LESS THAN 1 PPB • 1 TO 6 PPB n 7 TO 1 6 PPB 5H HORE THAN 1 6 PPB '0 500 FEET 0 1 5 2 H DISTANCE FROM SOUTH SHORE 6 E N D Cu IN LAKE SEDIMENT • LESS THAN 7 0 PPM • 7 0 TO 1 3 5 PPM • 1 3 6 TO 2 1 5 PPM • MORE THAN 2 1 5 PPM 0 500 FEET 0 152 M DISTANCE FROM SOUTH SHORE L E ZN IN LAKE HATER • LESS THAN 1 1 PPB • 1 1 TO 3 0 PPB • 3 1 TO 63 PPB B MORE THAN 63 PPB 0 500 FEET 0 152 M DISTANCE FROM SOUTH SHORE . G E N U ZN IN LAKE SEDIMENT • LESS THAN 2 5 0 PPM • 2 5 0 TO 1 8 0 PPM • 1 81 TO 9 3 0 PPM • MORE THAN 9 3 0 PPM 0 5 00 FEET 0 1 52 H DISTANCE FROM SOUTH SHORE m L E IN LAKE HATER LESS THAN 1 PPB 1 TO 3 PPB 1 TO 7 PPB MORE THAN 7 PPB * 0 . 0 • 6 . 1 • 1 2 . 2 • 1 8 . 3 • 2 1 . 1 • 3 0 . 5 0 5 00 FEET 0 1 5 2 M DISTANCE FROM SOUTH SHORE G E N D Mo IN LAKE SEDIMENT • LESS THAN 1 1 PPM • 1 1 TO 3 0 PPM © 3 1 TO 8 8 PPM • MORE THAN 8 8 PPH 0 500 FEET 0 152 H DISTANCE FROM SOUTH SHORE 0 500 FEET 0 . 1 5 2 H DISTANCE FROM SOUTH SHORE 0 500 FEET 0 152 H DISTANCE FROH SOUTH SHORE 0 5 00 FEET 0 1 5 2 H DISTANCE FROM SOUTH SHORE L E G E N D FE IN LAKE WATER FE IN LAKE SEDIMENT • LESS THAN 1 1 6 PPB • LESS THAN 3 . 2 Z • 1 1 6 TO 2 1 3 0 PPB o 3 . 2 TO 6 . 0 Z B 2 . 1 TO 1 1 . 2 PPH • 6 . 1 TO 1 1 . 3 Z £ 3 MORE THAN 1 1 . 2 PPH 9 MORE THAN 1 1 . 3 Z . L E G E N D ' MN IN LAKE WATER ' MN IN LAKE SEDIMENT •.LESS THAN 6 1 PPB • LESS THAN 1 3 0 0 PPM • 61 TO .520 PPB • 1 3 0 0 TO 5 0 0 0 PPH B 0 . 5 2 TO 1 . 2 7 PPH © 5001 TO 1 9 1 0 0 PPH BJHORE THAN 1 , 2 7 PPM© HORE THAN 1 9 1 0 0 PPH I F I G U R E 4 8 : T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D L A K E W A T E R ( P P B ) A L O N G L I N E S H A N D I , C A P O O S E L A K E tXJ O U4 1500 FEET 157 H 560 152 10*00 305 1*00 FEET 157 H DISTANCE FROM SOUTH SHORE DISTANCE FROH SOUTH SHORE 15*00 FEET 157 M DISTANCE FROH SOUTH SHORE L E G E N D Cu IN LAKE VIATER CU IN LAKE SEDIMENT • LESS THAU 1 PPB • 1 TO 6 PPB B 7 TO 16 PPB B MORE THAN 16 PPB L E G E N D ZN IN LAKE WATER ZN IN LAKE SEDIMENT • LESS THAN 70 PPM • 70 TO 135 PPH • 136 TO 215 PPH . • HORE THAN 215 PPM • LESS THAU 11 PPB • 11 TO 30 PPB B 31 TO 63 PPB HMORE THAN 63 PPB • LESS THAN 250 PPH • 250 TO 180 PPH • 181 TO 930 PPH 0 MORE THAN 930 PPH L E G E N D Mo IN LAKE WATER MO IN LAKE SEDIMENT o LESS THAN 1 PPB 8 1 TO 3 PPB B 1 TO 7 PPB H MORE THAN 7 PPB o LESS THAI) 11 PPM • 11 TO 30 PPM • 31 TO 88 PPM • HORE THAN 88 PPH 0« w 20. a 10. 1 5 60. a. " 80. 1001 1 1 i - T -1 . 1 r 1 '; J 1 * - i p 1 1. | — f - - — 1 1 — 1 •'. -1~ — - — — ... — — ... ... — — -— - -500 152 1000 305 1500 FEET 157 H DISTANCE FROH SOUTH SHORE 50*0 10*00 152 305 DISTANCE FROH SOUTH SHORE 1500 FEET 157 H 0.0 > 6.1. •12.2 •18.3 •21.1 •30.5 L E G E N D FE' IN LAKE WATER FE IN LAKE SEDIHENT • LESS THAN 116 PPB • LESS THAN 3.2Z • 116 TO 2130 PPB • 3.2 TO 6.0Z • 2.1 TO 11.2 PPH • 6.1 TO 11.3Z H MORE THAN 11.2 PPM® MORE THAN 11.3% L E G E N D MN IN LAKE WATER ' MN IN LAKE SEDIMENT > LESS THAN 61 PPB • LESS THAN 1300 PPH • 61 TO 520 PPB • 1300 TO 5000 PPM • 0.52 TO 1.27 PPH • 5001 TO 19100 PPH QHORE THAN 1.27 PPH® HORE THAN 19100 PPH F I G U R E 4 9 : T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D W A T E R ( P P B ) A L O N G L I N E J , C A P O O S E L A K E L A K E to o DISTANCE FROM SOUTH SHORE DISTANCE FROH SOUTH SHORE • DISTANCE FROH SOUTH SHORE L E G E N D Cu IN LAKE WATER CU IN LAKE SEDIMENT L E G E N D ZN IN LAKE WATER ZN IN LAKE SEDIMENT L E G E N D Mo IN LAKE WATER MO IN LAKE SEDIMENT • LESS THAN 1 PPB • 1 TO 6 PPB • 7 TO I S PPB M MORE THAN 16 PPB '• 10. ! 60« ' 80. 100. • LESS THAN 70 PPH • 70 TO 135 PPM • 136 TO 215 PPM ® HORE THAN 215 PPH i i ! 1 i T • 111 * £/ • Li— '^^;S-x.xS.i j^-i.-_~—r *N—' L - - . I l l " ~y t i \ i I i I i • LESS THAN 11 PPB • 11 TO 30 PPB • 31 TO 63 PPB B MORE THAN 63 PPB » LESS THAN 250 PPM • 250 TO 180 prH • 181 TO 930 PPH O MORE THAN 930 PPH s LESS THAN 1 PPB • 1 TO 3 PPB • 1 TO 7 PPB Q MORE THAN 7 PPB t LESS THAN 11 PPH • 11 TO 30 PPM • 31 TO 88 PPH • HORE THAN 88 PPH 500 152 1000 305 1500 FEET 157 H 1500 FEET 157 M C O N T O U R S R E P R E S E N T T E M P E R A T U R E I S O T H E R M S ; 6 ° , 8 ° , A N D 1 0 ° I S O T H E R M S A R E L A B E L L E D DISTANCE FROM SOUTH SHORE DISTANCE FROM SOUTH SHORE L E G E N D FE' IN LAKE WATER FE IN LAKE SEDIMENT • LESS THAN 116 PPB • LESS THAN 3.2Z • 116 TO 2130 PPB • 3.2 TO 6.0Z • 2.1 TO 11.2 PPH • 6.1 TO 11.31 SHORE THAN 11.2 PPM®MORE THAN 11.3Z L E G E N D MN IN LAKE WATER ' MN IN LAKE SEDIMENT • LESS THAN 61 PPB • LESS THAN 1300 PPM • 61 TO 520 PPB • 1300 TO 5000 PPH • 0.52 TO.1.27 PPH • 5001 TO 19100 PPH 13 MORE THAN 1.27 PPM® MORE THAN 19100 PPH F I G U R E 5 0 : T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D L A K E W A T E R ( P P B ) A L O N G L I N E K, C A P O O S E L A K E to o DISTANCE FROM SOUTH SHORE L E G E N D Cu IN LAKE VIATER • LESS THAU 1 PPB DISTANCE FROM SOUTH SHORE L E G E N D 5fl0 10*00 15*00 FEET 152 3C5 1)57 H DISTANCE FROM SOUTH SHORE 0« \ . 20« £ 10. I fE 60-" UJ ° 80« 1001 • 1 TO 6 PPB • 70 TO 135 PPM • 7 TO 16 PPB • 136 TO 215 PPM ! MORE THAN 16 PPB 9 MORE THAN 215 PP i -« i j i . I 1 f \ i 1 \ i t 1 / 1 / - - I _ -I ! J 1 . --- -: : i — -i.L.i. Cu IN LAKE SEDIMENT ZN IN LAKE WATER . LESS THAN 70 PPM • LESS THAN 11 PPB 11 TO 30 PPB 31 TO 63 PPB ZN IN LAKE SEDIMENT HO IN LAKE WATER • LESS THAN 250 PPM A LESS THAN 1 PPB . • 250 TO 180 PPM o 1 TO 3 PPB • 181 TO 930 PPM • 1 TO 7 PPB THAN 215 PPM 0 THAN 63 PPB 0 MORE THAN 930 PPM H MORE THAN 7 PPB L E G E N D flo IN LAKE SEDIMENT • LESS THAN 11 PPM • 11 TO 30 PPM • 31 TO 88 PPM • MORE THAN 88 PPM 500 152 1000 305 1500 FEET 157 M 0 0 DISTANCE FROM SOUTH SHORE 5*0 152 DISTANCE FROM SOUTH SHORE. 1500 FEET 157 M L E G E N D L E G E N D . FE' IN LAKE WATER FE IN LAKE SEDIMENT MM IN LAKE WATER ' HN IN LAKE SEDIMENT • LESS THAN 116 PPB • LESS THAN 3,21 • 116 TO 2130 PPB . o 3.2 TO 6.0Z B 2.1 TO 11,2 PPM • 6.1 TO 11.31 13 MORE THAU 11.2 PPM © MORE THAN 11.3Z • LESS THAN 61 PPB • LESS THAN 1300 PPM • 61 TO 520 PPB. • 1300 TO 5000 PPM • 0.52 TO 1.27 PPM • 5001 TO 19100 PPM EJ MORE THAN 1.27 PPM© MORE THAN 19100 PPM F I G U R E 5 1 : T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D L A K E W A T E R ( P P B ) A L O N G L L N E L C A P O O S E L A K E 207 F I G U R E 5 2 : D I S T R I B U T I O N O F L E A D ( P P M ) I N C A P O O S E L A K E S E D I M E N T 208 each other whereas enhancement i n Fe or Hn l e v e l s can be displaced 60 m on e i t h e r side. Fe most commonly accumulates i n deeper water upslope of zones of Mn accumulation. F a i l u r e of Cu, Zn and Mo to concentrate regularly within Fe or Mn-rich sediment suggests Fe and Mn scavenging i s not the p r i n c i p a l c ontrol on trace element accumulation. Two other trace element patterns merit further d e s c r i p t i o n . In the f i r s t , the South Zone mineral showing i s r e f l e c t e d by values of 380 ppm Cu, 1550 ppm Zn and 100 ppa Mo (ID - 281) i n a -80 mesh f r a c t i o n of sandy sediment 25 to 50 m from shore. Cu, Zn and Mo accumulation i s not complemented by Fe and an enrichment. Cu and Zn l e v e l s of f i n e r f r a c t i o n s further downslope are also enhanced (Table XXVI), reaching 1500 ppm Cu and 950 ppm Zn (ID - 173). Although Mo, Fe and Mn do not appear enriched i n association with s i l t and clay s p l i t s , t h i s probably r e f l e c t s t h e i r p r i o r solution during hypochlorite, d i t h i o n i t e and hydrogen peroxide pretreatments reguired by the K i t t r i c k and Hope (1963) sample disaggregation procedure. In the second d i s t r i b u t i o n , r e l a t i v e l y low values characterize the northern ends of Lines E, F and G. Low values are unexpected i n view of the Horth Anomaly upslope. However because the area l i e s downstream cf the presumed d i r e c t i o n of Capoose Creek flow i n the lake, low values probably r e f l e c t d i l u t i o n by sandy sediments of Capoose Creek. Size f r a c t i o n studies are unavailable to evaluate further t h i s d i s t r i b u t i o n . In view of the many parameters af f e c t i n g d i s t r i b u t i o n of trace elements i n Capoose Lake, multiple regression analysis, assuming Fe, Mn, organic matter and lake depth as indt-pendant 209 variables, was employed to help explain the Cu, Zn, So and Pb v a r i a b i l i t y (Table XXXI). Following t h i s analysis, 73.4% of the Cu and 54.4% of the Zn v a r i a b i l i t y could be attributed to variations in organic matter and Fe content. Pb and Ho v a r i a b i l i t y i s apparently controlled by Fe accumulation, whereas lake depth i s important i n explaining Hn d i s t r i b u t i o n s . In order to evaluate further significance of the regression analysis, selected lake sediment samples were analyzed by the sequential extraction procedure. Previously determined • t o t a l * trace and minor element concentrations are divided into components associated with organic matter, carbonate minerals, amorphous Mn oxides, amorphous Fe oxides; c r y s t a l l i n e Fe oxides and s i l i c a t e residues. Trace o c t a l concentrations dissolved by many of the sequential extraction reagents follow the double peak d i s t r i b u t i o n ; However, contrast between high and low values i s commonly improved over * t o t a l * determination data because r e l a t i v e l y constant components of the'*total* metal content can be separated from components associated with ac t i v e l y scavenging f r a c t i o n s . The double peak d i s t r i b u t i o n i s best i l l u s t r a t e d by Mn data along Line K (Fig 53). Well-developed maxima f i r s t seen i n • t o t a l * determination data are repeated on dissolution of amorphous Mn oxides (hydroxylamine hydrochloride), amorphous Fe oxides (acid ammonium oxalate), c r y s t a l l i n e Fe oxides ( d i t h i o n i t e ) , s i l i c a t e residues (concluding n i t r i c / p e r c h l o r i c a c i d s ) , exchangeable Mn ( a c i d i f i e d d i s t i l l e d water), and hydrogen peroxide soluble Mn. Di s t r i b u t i o n of Mn associated with organic matter (hypochlorite) i s s t r i k i n g l y d i f f e r e n t , with Table XXXI Multiple regression analysis of the trace metal content of s u r f i c i a l sediment of Capoose Lake, assuming t o t a l i r o n , organic matter and lake depth independent va r i a b l e s log£ Cu ] = 0.0215[OM] + 0. 6781og[F9 ] + 1.34 R 2 = 73 .4% log[ Zn ] = 0.0117[OM] + 0.612log[Fe] + 2.00 R 2 = 54 .4% log[ Hn ] = .1. 2431og[ Fe ] + [D] + 2.26 R 2 = 64 .1% log[Pb ] = 0. 6071og[Fe ] + 0.77 R 2 = 41 .9% log[ Mo ] = 1.271log[Fe ] + 0.42 R 2 = 68 M n= 1 2 2 R e g r e s s i o n e q u a t i o n s c a l c u l a t e d by backwards s t e p w i s e r e g r e s s i o n u s i n g the UBC *TRIP computer program. D i s t a n c e from s h o r e , water t e m p e r a t u r e , and w a t e r pH were assumed i n i t i a l l y t o be independent v a r i a b l e s , b u t were f o u n d t o be i n s i g n i f i c a n t i n e x p l a i n i n g t r a c e element v a r i a b i l i t y OM - O r g a n i c m a t t e r c o n t e n t d e t e r m i n e d by the Leco method D - l a k e d e pth 211 greatest values observed near the middle of the lake. In other parts of the lake; prominence of double peak d i s t r i b u t i o n s depends on the element considered and the reagent employed. In some cases, obscure double peak relationships among • t o t a l * data may become a c h a r a c t e r i s t i c feature of several of the sequential extractions (Figs 54 to 56)a Besides double peak d i s t r i b u t i o n s , metal l e v e l s may be enhanced near the middle of the lake. Organically bound forms of Cu, Zn, Mo,* Fe and Hn i n the east follow t h i s pattern, and for t h i s f r a c t i o n perturbations r e f l e c t i n g the break of slope are not apparent. By contrast, organically held trace elements i n the west are usually highest nearshore (Figs 54 to 56), accounting for approximately 105S of the * t o t a l * metal content near the middle of the lake. Consequently retention of trace elements by organic matter i s not d i r e c t l y proportional to the quantity of organic matter expressed i n terms of organic carbon content, but depends on chemical properties of the organic f r a c t i o n . Also observed i s a less cotaion d i s t r i b u t i o n whereby metal extraction i s r e l a t i v e l y constant across the lake, declining or attaini n g minimum or maximum values only nearshore. Solution of flo or Fe by acid ammonium oxalate i l l u s t r a t e s t h i s trend. In addition to double peak d i s t r i b u t i o n s , and patterns r e f l e c t i n g enrichment near the middle of the lake or r e l a t i v e l y constant l e v e l s across the lake, random d i s t r i b u t i o n s apparently characterize metal extraction by weaker reagents. These cannot be correlated with physical or chemical properties of lake sediment. 211A P R E F A C E T O F I G U R E S 5 3 T O 5 6 : U P P E R I L L U S T R A T I O N : 1 , S O D I U M H Y P O C H L O R I T E E X T R A C T I O N / P H 9 . 5 2 . W E A K L Y A C I D I C D I S T I L L E D W A T E R , P H 3 , 0 3 . H Y D R O X Y L A M I N E H Y D R O C H L O R I D E E X T R A C T I O N / PH 2 . 5 4 , A C I D A M M O N I U M O X A L A T E E X T R A C T I O N , P H 3 . 5 L O W E R I L L U S T R A T I O N : 1 . D L T H I O N I T E E X T R A C T I O N / PH 7 . 0 2 , H Y D R O G E N P E R O X I D E E X T R A C T I O N , P H 3 . 0 3 . N I T R I C / P E R C H L O R I C A C I D D I G E S T I O N O N R E S I D U E 4 , N I T R I C / P E R C H L O R I C A C I D D I G E S T I O N ' T O T A L ' D E T E R M I N A T I O N , ( N O T E ' T O T A L ' - F E R E P O R T E D I N P E R C E N T ) 212 1011.0(10 r.o.noo 20.001) 10.000 5000 a. 2000 a . 1000 • noo Z o 200 — 100 »-< 30 t- 20 Z 10 ni u z -o 1 u 0.3 0.2 N 200 l(io (.oo lion D I S T A N C E - FEET LEGEND] l cut: - 2 0J2I .3 cvnj i a-v I t o o 1 6 0 0 l . ' l u i i 2oi io 2 0 0 M LEGEND! z o < Oi. r-z UJ V z o u N lOO.OOII . " . l l . l l l l l l , 20.000 ' 10.000 5(>liO 200n 1000 300 200 loo 0.2 200 ino (,oo i:oo D I S T A N C E - FEET • C J J -cw 1200 1101) 161)0 liiOO 2000 2 0 0 M t i I, > F I G U R E 5 3 A : S E Q U E N T I A L E X T R A C T I O N O F C O P P E R F R O M L A K E S E D I M E N T S A L O N G L I N E K / C A P O O S E L A K E 213 In:).(Hill ."•(l.liiil) 20.000 10,(1(10 .".()()(l o. 2000 a. 1(100 i Slid Z o 20(1 —- 100 < 50 20 z 10 UJ .> U •> z o I u ()..-. 0.2 N 2 o o mo ftiio :i(io D I S T A N C E - F E E T LEGEND] " 2 ZNS .•> 7.-I7 < ZN3 I K I O K>oo i;:ni> -:-.oo 2 0 0 M F I G U R E 5 3 B : S E Q U E N T I A L E X T R A C T I O N O F Z I N C F R O M L A K E S E D I M E N T S A L O N G L I N E ( 0 C A P O O S E L A K E 10(1.(111(1 5 0 . 0 0 1 1 2 0 . 0 0 0 lo.ooo . " 0 0 0 a. 2 0 0 0 a. : looo • 5 0 0 Z o 2 0 0 1 0 0 < 30 •- 2 0 z 10 UJ •> U z -o 1 u 0 . 5 • 0 . 2 JL \ LEGEND] l r e i ] -2 F£2| .3 FE3! — FE4 Ki l l f • l is > .".(ill K ioo I2''i> l i n o K i l l " I:: (: i 1 2 0 0 M D I S T A N C E - F E E T S u (1 200 100 6 0 0 !!(!() 1 0 0 0 1200 I 1 0 0 1600 li',00 2000 I D I S T A N C E - F E E T 2 0 0 M £ F I G U R E 5 3 C : S E Q U E N T I A L E X T R A C T I O N O F I R O N F R O M L A K E S E D I M E N T S A L O N G L L N E K/ C A P O O S E L A K E 215 C L z o < at >-Z tu U z o u . " 0 . 0 0 0 2 0 . 0 0 O 1 0 . 0 1 ) 0 S O O I I LEGEND 1 -".SI j "2 KN2! .3 KM ! 4 M;K D I S T A N C E - F E E T LEGEND! Km.000 . " l O . O O O 2 0 . 0 0 0 lo.ooo r>iioo 0. 2 0 0 0 o. looo 1 r,i)i) Z O 2 0 0 — 1 0 0 < no Of 2 0 V-Z 1 0 U i .1 U Z o 1 u o.."> 0 . 2 2 0 0 I fio (.oo D I S T A N C E - F E E T no looo 120(1 I loo If.oo li'.o'i 2 0 0 M F I G U R E 5 3 D : S E Q U E N T I A L E X T R A C T I O N O F M A N G A N E S E F R O M L A K E S E D I M E N T S A L O N G L I N E K' C A P O O S E L A K E 216 LEGEND! l u o . i i o o .">(i.tin:i 20.01)1) 10.000 JL ..(100 C L 2 0 0 0 a. 1000 i .jOO Z o 2 o o —— 100 < SO OC 2 0 Z 10 U J • 1 U z ~ o 1 u o. r» :t -Jul i K i n fiint :;r.it inn:) IJ ' . i t I inn | M - : . I 2 0 0 M D I S T A N C E - F E E T LEGEND] i t ' ' .1 .1111 2i».ot>o lii.r.Oii " o o o a. 2 o i i o a. I'lOO i J i m Z o 2 0 O — 100 < .>!> 2 o 1— z 10 U J .» U z — o 1 u 0.." (1.2 N — M:M i m n 6 o i ) r. o n l o o o 1200 l i n o I600 i ; ; o o 2 0 0 0 2 0 0 M o. 2 0 0 D I S T A N C E - F E E T F I G U R E 5 3 E : S E Q U E N T I A L E X T R A C T I O N O F M O L Y B D E N U M F R O M L A K E S E D I M E N T S A L O N G L I N E K / C A P O O S E L A K E 217 LEGEND] 5 C O . I Z o < z UJ U z o u i L lIMI.ODO 30.noii 2(1.000 lo.ooo . i i imi 2000 IO0II 500; 200 l i l t ) 5 0 1 CU! D I S T A N C E - F E E T i I K I W I i " I ' M | l o n i f - m t j;:n<i v i n i i 2 0 0 M CU2 CU3 •CU4 LEGENDS 5 OL a. i Z o < OL »-z UJ U z o u JL : i l l l . o i : i > . " » o . u ; ; p 2 O . 0 O O 1 0 . 0 0 0 . - . ( 'Oi l 2 0 o o • l o o o 2 0 0 l o o 5 0 2 0 1 0 V \ -7-1 CIS 2 C'J6 3 CU7 4 cua 200 too 6110 Boo D I S T A N C E - F E E T 1 2 0 0 1 1 0 0 1 6 0 0 1,'iOO 2 0 0 0 2 0 0 M F I G U R E 5 4 A : S E Q U E N T I A L E X T R A C T I O N O F C O P P E R F R O M L A K E S E D I M E N T S A L O N G L I N E C , C A P O O S E L A K E 218 CONCENTRATION - PPM LEGEND CONCENTRATION - PPM CONCENTRATION - PPM , — — — • 1 ZN5 CONCENTRATION - PPM - 2 Z.'(Q — 3 ZH7 CONCENTRATION - PPM 4 ZN3 CONCENTRATION - PPM CONCENTRATION - PPM CONCENTRATION - PPM CONCENTRATION - PPM CONCENTRATION - PPM ^ N N , \ " CONCENTRATION - PPM r X / \ CONCENTRATION - PPM CONCENTRATION - PPM CONCENTRATION - PPM CONCENTRATION - PPM CONCENTRATION - PPM CONCENTRATION - PPM CONCENTRATION - PPM > 2 no imi 6 i m . ;:o<> mm 1 2 0 0 i-m<> t 6 n o UMHI ' 2I>OD D I S T A N C E - F E E T , 2 0 0 M . O F I G U R E 5 4 B : S E Q U E N T I A L E X T R A C T I O N O F Z I N C F R O M L A K E S E D I M E N T S A L O N G L L N E C , C A P O O S E L A K E LEGEND? a. I z o < at t -z UJ U z o u l o o . o o o 50.000 2 0 . 0 0 0 1 0 . 0 0 0 50OO C o n n l o o o 3 0 0 2 0 0 i n n s o 2 o i n S SI \ / . H o n let :tt D I S T A N C E - F E E T 2 0 0 M " LE5F.N0 2 FE2 -3 FE^  4 FE4 LEGEND! 3 a. Z o < Of z UJ U z o u S O . o n o 2 0 . n o : ; ' l o . o o u ."00o|-2000 1C.00 s o n -i o n • l o o -S o f 2 0 1 0 -2 F^ c fi\ 2(l(, . 1 0 0 6 0 0 HOO 1 0 0 0 1 2 0 0 1 1 0 0 1 6 0 0 lilOO 2 0 0 " 2 0 0 M D I S T A N C E - F E E T F I G U R E 5 4 C : S E Q U E N T I A L : E X T R A C T I O N O F I R O N F R O M L A K E S E D I M E N T S A L O N G L L N E C / C A P O O S E L A K E F I G U R E 5 4 D : S E Q U E N T I A L E X T R A C T I O N O F M A N G A N E S E F R O M L A K E S E D I M E N T S A L O N G L I N E C, C A P O O S E L A K E 221 o. I Z o < ta t-Z UJ U z o u 1 L t l lO .OI lO 20.0DI) 10.01)11 5000 l o o o 7 L D I S T A N C E - F E E T 2 0 0 M LEGEND! 1 H O I I - « 2 - : « . j o n t o n ( , o n : ; i : o I I H I « > l ; . ' i . ' o l l o o I d o i i i : : n o : ' o o o LEGEND! t *tj* • 2 M.OG .3 K 0 7 4 yi;g 1 2 0 1 ) 1 6 0 0 1111)11 2 0 0 M S a. Z o t— < i -z UJ U z o u l o n . o n o 000 2o.:ino 10.(Kill .-.coo 2ooo looo .-.on 200 K M 30 20 10 Jl D I S T A N C E - F E E T F I G U R E S E Q U E N T I A L E X T R A C T I O N O F M O L Y B D E N U M F R O M L A K E S E D I M E N T S A L O N G L L N E C , C A P O O S E L A K E LEGEND] o_ a. • Z o < t-z UJ u z o u i L Io::.o:;u l O . O i i i i S o o n loon 3011 loo S O 0.2 7K 200 - i f i o film-D I S T A N C E - F E E T 1000 1200 I10O 1600 1)10(1 2 0 0 M l o o . o o o 30.000 20.000 10.000 . 3000 • pp 2000 1000 z • 500 0 2oc 100 < 3 0 OS V- 2n Z 10 U J * j U z •> 0 1 u 0.3 0.2 £-t-. - ' 1 tf--rtr T T •J LEGEND] 1 CU5 • 2 CU5 . 3 C J 7 4 CU3 •jnn 1 ni) f.ni} ;:oo D I S T A N C E - F E E T looo 1200 Hon "'OO •'"»" 2 0 0 M F I G U R E 5 5 A : S E Q U E N T I A L E X T R A C T I O N O F C O P P E R F R O M L A K E S E D I M E N T S A L O N G ' L I N E E / C A P O O S E L A K E 223 LEGEND! inn.linn ,">n.!:,in 20.0011 IIUKIO ."ninii a . CL. liiiiii 1 Z 5(i() o ion ion < 50 OC 1- 20 Z 10 UJ 5 U Z o o 1 u 0.5 0.2 i L 200 loo 6oo lion D I S T A N C E - F E E T 120(1 11011 1600 i;:oo 2 0 0 M 2000 5 z o I— < t— z UJ u z o u N 100.0011 50.000 20,00(1 10,000 3000 200O loon 50(1 2<)(i . 100 30 20 10 -y-'—— LEGEND! 1 IN5 . 3 - 2 . ' i 7 [ 4 Z.N3 200 loo 600 sum D I S T A N C E - F E E T 120 (1 1100 16110 lolll) 2 0 0 M F I G U R E 5 9 3 : S E Q U E N T I A L E X T R A C T I O N O F Z I N C F R O M L A K E S E D I M E N T S A L O N G L I N E E / C A P O O S E L A K E 224 5 o_ a. i z o t-< y-Z UJ U z o u lot:.no lIM'll S o n KM ± ._/ I  20(1 -1(1(1 GOO i ' . o o D I S T A N C E - F E E T loon 1200 1100 10OI) li'.OO 2 0 0 M LEGEND] 1 fr.l -2 ra .3 FE3| n rc, z o < U Z o u J L 20.000 20111 10(1(1 1 0 0 100 (.00 D I S T A N C E - F E E T looo . 1200 I mo looo. 1000 2 0 0 M LEGEND! 1 FE3 j •2 FEo' . 3 FE7 < FE8 F I G U R E 55C: S E Q U E N T I A L E X T R A C T I O N O F I R O N F R O M L A K E S E D I M E N T S A L O N G L I N E E , C A P O O S E L A K E 225 LEGEND! OL Ct. I ' Z O t— < DC z U z o u 1011.000 J I U I I M I 20.0110 ll).(HII) 5(111(1 D I S T A N C E - F E E T 2(10 .1(111 dOO !!(!() 1000 1200 1100 160(1 liKMI 2000 2 0 0 M 100.000 30.000, 20.000 10.000 1 • 5000 a. 2000 a. 1000 500 z o 20(1 1— 100 < 50 y- 20 Z 10 Ul U z • ** o t u 0.5 0.2 7-LEGEND] 1 W5j . 3 KN7 4 ns:s 2 0 0 1 0 0 6 0 0 " 0 0 1 0 0 0 1 2 ( 1 0 D I S T A N C E - F E E T I 1 0 0 1 6 0 0 1 . " .00 2 C O O 2 0 0 M s F I G U R E 5 5 D : S E Q U E N T I A L E X T R A C T I O N O F M A N G A N E S E F R O M L A K E S E D I M E N T S A L O N G L I N E E / C A P O O S E L A K E LEGEND! 1 r . s i - 2 x:? _ 2— 4- p,Z4 5 CL a. • Z o < Of z ui U z o u JL l l l . O O i KMIIlf 0.2 t 200 i n n f i l m l i n o D I S T A N C E - F E E T 10(10 12(11) inn) i6im iiKio 2("in 2 0 0 M F I G U R E 5 5 E : S E Q U E N T I A L E X T R A C T I O N O F M O L Y B D E N U M F R O M L A K E S E D I M E N T S A L O N G L I N E E , C A P O O S E L A K E 227 loo.noo 30.000 20.01)11 io.ooo 50OO O U 2000 o. looo • 3oo Z o 200 t— 100 < 30 t- 20 Z 10 UJ -U z -o 1 u 0.5 0.2 JL LEGEND] i cui " 2 C U 2 .3 CU3 4 QM 2oo I I:CI f ,oo ::on l o ' i o |2m> l i o n l o o o |;:oo 2000 D I S T A N C E - F E E T 2 0 0 M 100.000 .'l>.0:)0 20 .000 10.000 Soon 2000 O L looo • .".00 Z O 200 — loo < 50 en H- 2o Z 10 UJ 5 U z ~ o I u (1.5 0.2 J L LEGENOi •: osj - 2 CUGJ .•? CU7j « an 201) 100 600 K('t) D I S T A N C E - F E E T 1000 1200 _ 1100 1600 IIIOO 2000 2 0 0 M F I G U R E 5 6 A : S E Q U E N T I A L E X T R A C T I O N O F C O P P E R F R O M L A K E S E D I M E N T S A L O N G L I N E G / C A P O O S E L A K E 228 5 cu a . t Z o < en t-Z Ul U z o u 100.000 30.000 20.000 10,000 3000 2000 1000 500 LEGEND : z;i: -2 2N2 .1 z;<? 4 Z . v , 2i.o Mo i " in lo'-o 1200 lloo !•••"> i::mi : I I U O D I S T A N C E - F E E T 2 0 0 M loo.mill 50 .000 20.000 10,000 5000 a. 2000 a. 1 0 0 0 i 500 Z o 200 — 100 < 50 ct: 20 t-Z 10 UJ 5 U a z o I u 0.5 0.2 N 200 100 600 1100 D I S T A N C E - F E E T 1 2 0 0 1 1 0 0 1 6 0 0 i::oo 2 0 0 M LEGEND ZN7 v;.o F I G U R E 5 6 B : S E Q U E N T I A L E X T R A C T I O N O F Z I N C F R O M L A K E S E D I M E N T S A L O N G L L N E G, C A P O O S E L A K E 229 L E G E N D ! 10(1,0(11) 30.001) 20 ,000 10,000 5000 CL. 2000 a. 1000 Z 500 o 200 100 < 51) ce t- 20 Z 10 UJ _ U z •> o 1 u 0.5 0.2 -FE?. •••V, 200 loo i,oo :'.()<> D I S T A N C E - F E E T loon 1200 IIOO moo i;;oo 2000 2 0 0 M loo.000 50.000 20 .000 10,001) 5000 CL 2000 1001) ' 500 Z O 200 »- 100 < s o r- 20 z to UJ -u z 0 1 u 0.5 0.2 J L 2 0 0 1 0 0 D I S T A N C E 600 <IOO - F E E T . 1600 l i l o n 2 0 0 M L E G E N D ! •F •F<0 2000 - s F I G U R E 5 6 C : S E Q U E N T I A L E X T R A C T I O N O F I R O N F R O M L A K E S E D I M E N T S A L O N G L L N E G, C A P O O S E L A K E 230 i n n . n u n r > n . i i i ) i ) 211.111)11 10,000 5I IDD % o. a. 11)011 t 31)0 Z o 200 100 < S O OS 2o z 10 at <* U z •» o 1 u 0.5 0.2 JL D I S T A N C E - F E E T 2 0 0 M LEGEND] "2 IMI . 3 :-JW3l 4 «(4 2oo l o o i,oo :;oo looo 12011 I loo l o o o i:;oo 2000 s F I G U R E 5 6 D : S E Q U E N T I A L E X T R A C T I O N O F M A N G A N E S E F R O M L A K E S E D I M E N T S A L O N G L I N E G, C A P O O S E L A K E 231 LEGEND! 100.1)1 I I ) .10.00(1 20.000 10,000 300(1 a. 2000 a. 1000 500 Z o 200 100 < 50 en t- 20 Z 10 U i -U z •> o I u 0.5 0.2 <—.w i 2 I H I l o o ( • • i n I ' . ' m I U I I I I | 2 I M ) I l o o I M H I | : : • H I -">oii D I S T A N C E - FEET . 2 0 0 M  S 100.01)0 50.000 20.000 10,0011 _g 5000 0. 2000 a. 1000 z 3 "" O 2<") - 100 < 50 en y- -<> Z u» UJ -, U z -O 1 {J 0.5 0.2 1 N LEGENO •> ;-7 c « : a — _ — y . \ / / . / / / > 200 100 000 1101) _ l<>0<>. 1200 .1100 16!M> liillll 2000 D I S T A N C E - FEET . 2 Q O M ^ ^ F I G U R E 5 6 E : S E Q U E N T I A L E X T R A C T I O N O F M O L Y B D E N U M F R O M L A K E S E D I M E N T S A L O N G L L N E G, C A P O O S E L A K E 232 D i l u t i o n of trace elements by Capoose Creek inflow, and anomalous accumulation of metals near the South Zone are evident among sequential extraction data, and a combination of these factors contribute to a general increase of values from north to south. The trend i s exemplified by release of Cu on d i s s o l u t i o n of amorphous Fe oxides and s i l i c a t e residues (Figs 54 to 56). Influence of sand d i l u t i o n i s also i l l u s t r a t e d by Zn content of the f i n a l residue (Figs 53 to 56). Though Zn values i n proximity to the South Zone are 200 ppm, near Capoose Creek contents are only 50 ppm, increasing with distance from the creek to 75 ppm along the north end of Line E, and 150 ppm along Line C. These values compare to 75 ppm of the delta (Line I ) , and 50 to 100 ppm contents i n the eastern half of the lake. In an analogous fashion, trace element contents dissolved by many of the seguential extraction reagents are reduced by proximity to Capoose Creek. Line E overlies that portion of the lake f l o o r c l o s e s t to the South Zone; Trace element patterns r e f l e c t i n g the sulphide occurrence are evident i n proximity to mineralized bedrock. Anomalous conditions are indicated by enhanced l e v e l s and improved anomaly contrast among amorphous Fe oxide-bound, s i l i c a t e residue-bound, and organic-bound Cu, Zn and Mo. Best anomaly contrast i s seen for Cu (10X background of 10 ppm) and Zn (100X 5 ppm) contents held by organic matter. Though amorphous Fe oxides hold an average of 50 ppm Zn, only a broad 2X enhancement l i e s adjacent to the mineralized zone., The South Zone i s also indicated by other extraction data. Fe and Mo enhancement i n d i t h i o n i t e or hydrogen peroxide extracts r e s u l t s 233 i n a s p i k e - l i k e anomaly (Fig 54). A marked increase i n Cu and Zn extraction by a c i d i f i e d d i s t i l l e d water and hydroxylamine hydrochloride indicates readily-soluble metals are also concentrated i n proximity to mineralized bedrock. A second zone of enhanced Cu and Zn concentrations i n a readily soluble form along the northern end of Line G (Fig 56) may be the only i n d i c a t i o n of the North Anomaly showing i n Capoose Lake. * In addition to enhancement of metal l e v e l s associated with organic matter, Cu, Zn and Fe content of organic f r a c t i o n s near the South Zone occurrence are also r e l a t i v e l y impoverished near the base of the nearshore slope (Fig 54). These minima are unusual i n that they l i e remote from Capoose Creek inflow, are antipathetic to metal enrichment i n other extracts and are not associated with any obvious p e c u l i a r i t i e s i n organic matter composition or concentrations Previous trace element d i s t r i b u t i o n s describe metal content of the upper 0 to 5 cm of recent sediment - the depth sampling range of the mud snapper. In view of previous work by Gorham et a l (1974)' who consider sediment from these depths to be subject to seasonal v a r i a b i l i t y , samples were collected from greater depths using a Phleger corer. Core sampling, conducted near the South Zone, commences at sample number 293 in the south and conclude at 301 i n the north (Fig 23; Tables XXXII and XXXIII). Lake cores can be divided into 3 classes according to trace element l e v e l s , sample texture and r e l a t i v e position within the lake. In a l l groups, concentrations of trace elements i n southern cores commonly exceed leve l s of the same elements i n northern cores. For example, cores 293 and 301 from the Table XXXII Location of Capoose Lake core samples S a m p l e D i s t a n c e f r o m L a k e N u m b e r S o u t h N o r t h D e p t h S h o r e S h o r e m is m ' S h o r e 0 4 1 6 0 . 0 2 9 3 15 4 0 1 6 . 7 2 9 4 3 7 3 9 0 1 0 . 7 2 9 5 6 2 3 6 4 1 8 . 0 2 9 6 1 2 3 3 0 3 2 5 . 9 2 9 7 1 8 3 2 4 3 2 9 . 9 2 9 8 2 4 4 ' 1 8 2 3 0 . 0 2 9 9 3 0 5 1 2 1 2 8 . 7 3 0 0 3 6 6 6 0 2 0 . 4 3 0 1 3 9 6 3 0 1 1 . 6 S h o r e 4 16 0 0 . 0 235 Table XXXIII Trace element content (ppm) i n lake sediment c o r e s from Capoose l a k e , -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c a c i d a t t a c k CCF.E HUBBEB 293 Depth cm Cu PP" ZD PP" Fe % Bn PP" Bo ppo Sand X 0 5 5 8 8 16 16 18 18 19 42 .2 121. 83 .8 413 . 540 . 514. 7 0 C . 390 . 211b: 2230. 4.91 4 .C4 4 . 0 0 6 .52 6 .27 536. 730. 662. 4350 . 5040. 3 .0 5 .0 4 . 5 9 .0 100. 65 .7 29 .8 5 6 . 3 8.2 16.6 CCBE SUBBEB 294 Depth C O Cu pp. Zn PP" Fe % Hn . FF» Ko PP" Sand « 0 5 6 11 i i m 138. 145 . 137. 57 .8 54 .0 41 .3 6.02 5 . ee 6.57 1950. 701. 7S6 . 4 .0 3 .0 3 . 5 1.5 5 .0 9.0 Depth C D Cu ppo 0 5 140. 5 8 138. 8 13 158. 13 17 U 0 . 17 21 153. CCBE SCBBEB 295 Z D PF» 56.2 50 .6 3 8 . 3 16. 1 51 .3 Fe % 10.2 8.56 8. 18 6.50 8.60 an PF° 31S0. 1460. 1330. 1240. 2130. no PP° 5.0 3 .5 4 .0 7 . 5 5 .0 Sand X . 9 .5 .4 .4 1.9 CCF.E H0BEEB 296 Depth cu Zn cm PP" PP" 1 4 138. 50 .8 4 8 147 . 36 .3 8 13 129. 36. 4 13 16 114. 11 .8 16 19 143. 40 .0 19 22 141 . 29 .6 Fe X (In PP" 9.62 18600. 11.1 11.0 6.53 10.9 10,1 8810. 5670. 2900. 5S70. 6630. Bo FP» 1 .5 2.0 1 . 5 4.0 1 . 5 2.0 Sand * 1.2 1.5 .8 .8 . 5 .7 COBE 110KBEB 297 Depth C U cn I pp" 0 4 129. 4 6 | 1 2 0 . 6 9 S2.7 9 12 j 1 0 9 . 12 1 8 ! " 7 . Zn Fe Bn Bo Sand PP" % PP" FF» * 37.0 7.75 1670. 4 .0 .8 294 . 6 .39 702. 10.0 . 3 285. 6 .4b 7CB. 10.0 .4 355 . 6.38 863. 10.0 .2 297 . 8. 66 893. 12 .5 .3 CCBE NUBBLE 298 COBE NUflBER 300 Depth co 0 5 5 14 14 21 21 30 30 38 38 40 CCBE KUrtBER 301 Depth Cu Zn Fe Bn Bo co PP" PP" » PP" PP" 0 8 6 0 . 3 279. 4. 16 589 . 2 .5 8 15 55 .8 236. 3 .49 325. 2 .5 15 17 77 .8 193. 5.24 29b . 3 .0 17 30 4 6 . 7 216. 3 .72 202. 2 . 5 Depth Cu Zn Fe Hn' ' Bo Sand C O PP" PP" X PP* ppo X 0 3 125. 421 . 7 .42 .2710. 12.5 . 9 3 7 107. 290. 6 .35 1100. 12.5 . 6 7 10 105. 232. 7.31 892. 12 .5 .4 10 12 117. 317. e. 15 1220. 6 .5 . 7 12 20 120. 237 . 7 .35 1000. 6 .5 . 6 20 28 105. 118. 6.21 904. 4 .0 3.1 CCBE NUBEEB 299 Depth Cu Zn Fe Bn Bo Sand C O PP" FP» X PP" PP" X 0 4 117. 399 . 10.2 4680 . 4 .0 1.0 4 12 114. 392. 8.69 3330. . 15.0 2 . 0 12 20 107. 295 . 8 .73 2140. 7 .5 . 9 20 25 113. 302. 8.30 1720. 5.0 .6 25 30 118. 130. 6 .20 1220. 4 .0 . 5 Cu Zn Fe Bn Bo Sand ppo PF» X FP" FP" X 100. 330. 6 .53 1770. 10 .0 4 .4 112. 366 . 6 .09 1250. 6 .0 5.4 103. 261. 6 . 39 936. 5 .0 5 .2 138. 164. 5.94 969. 7 . 5 .1 96 .0 310. 4 .93 617. 6 .0 10.1 61.2 279 . 5 .23 684. 2 .5 7 .0 Sand X 24.6 . 35.3 7.3 42.2 236 nearshore environment contain s i m i l a r metal levels and sand contents at the sediment - water interface (Table XXXIII). However Cu, Zn, Mo and Hn l e v e l s near the South Zone increase subs t a n t i a l l y from 40 PFm, 500 ppm, 3 ppm and 400 ppm at surface to 500 ppm, 2000 ppm, 100 ppm and 4000 ppm at depth, respectively. This trend i s opposite to the sand d i s t r i b u t i o n (-80, +270 mesh fraction) which decreases from 65% at surface to 1056 at depth. Compared* to core 293, trace element content of core 301 remains approximately constant along i t s length, showing a s l i g h t enhancement at 15 cm depths correspondig to a f i n e l y textured sediment. Fe concentrations i n both sections e x h i b i t l i t t l e v a r i a t i o n with depth. Cores 291 and 300 were also co l l e c t e d i n r e l a t i v e l y shallow water and contain 5 to 10$ sand. Bithin core 300, many trace element d i s t r i b u t i o n s to 24 cm are s i m i l a r to those of other cores in deeper parts of the lake. However trends towards increased or decreased metal l e v e l s with depth are commonly reversed below 24 cm depths. For example, the Zn content at 12 cm i s approximately the same as at 36 cm. However the Zn value at 24 cm, the greatest depth attained by the Phleger corer elsewhere i n the lake, i s at a minimum. S i m i l a r l y , the Cu d i s t r i b u t i o n displays a maximum at 24 cm whereas i n other sections the Cu content appears to remain approximately constant with depttu Notwithstanding that depth trends of trace metal l e v e l s may be d i f f e r e n t i f additional samples could be obtained from deeper i n t e r v a l s , Cu, Zn, Mo and Mn l e v e l s i n cores 294 and 300 appear s i m i l a r and usually diminish with depth, fly contrast, Fe l e v e l s increase s l i g h t l y with depth. 237 Further into the lake, sediment consists of finely-textured material, and sand comprises le s s than II of the sediment. In the south, the breaX i n slope environment i s associated with Fe and Hn enrichment to 11% and 1.9% l e v e l s , respectively, i n s u r f i c i a l sediment'(cores 295, 296), and Zn impoverishment from 500 to 50 ppm l e v e l s . By contrast, values in the north (core 299), though s i m i l a r i n Fe content, contain up to 8X more Zn and 1/3 of the Mn. Zn, Mn and Fe contents usually diminish with depth. In the south, a minimum i n Zn, Fe and Mn concentrations at 11 cm depths i s accompanied by enhanced Mo concentrations. Trace element relationships change markedly below base of the nearshore slope. Several depth trends are discernable i n core 297, including a pronounced maximum i n Mn, a marked minimum i n Zn and Mo l e v e l s at surface, and r e l a t i v e l y featureless Cu and Fe d i s t r i b u t i o n s . Mn and Fe concentrations are 1/10 and 1/2 of previous values, respectively. In a s i m i l a r l y s t r i k i n g fashion, Zn l e v e l s return to values comparable to core 293. , Although data from cores 297 and 298 are almost i d e n t i c a l , i n core 298, Zn and Mo values are highest at surface and decrease with depth. 4. Discussion Within the Capoose lake watershed, metal transfer from Cu -Ho or Pb - Zn mineral occurrences to overburden i s a c t i v e l y proceeding by a combination of mechanical and hydromorphic mechanisms. Relative importance of one or the other depends on l o c a l conditions, and can be inferred from the r e l a t i o n s h i p between s o i l anomalies and topography, and from mechanics of 238 trace element retention i n overburden materials. For example, Cu or ffo s o i l anomalies coinciding with seepage zones or ly i n g along topographic i n f l e c t i o n s commonly have an epigenetic o r i g i n . However where anomalies are associated with r e s i d u a l overburden, p a r t i c u l a r l y near mineralized bedrock, they probably have a syngenetic genesis. Origin of geochemical anomalies can also be i n f e r r e d from the strength of trace element retention i n overburden samples. If" a high proportion of the • t o t a l * metal content i s released only a f t e r digestion of the f i n a l sequential extraction residue, the assumption can be made that the anomaly has a syngenetic o r i g i n . By contrast, i f r e l a t i v e l y large quantities of trace elements are released by solution of amorphous or c r y s t a l l i n e Fe oxides or organic t a t t e r , i t can be assumed that metal accumulation proceeds via scavenging by these sample f r a c t i o n s . S o i l anomalies having a syngenetic o r i g i n commonly exhibit an increase in trace element contents with depth, whereas anomalies having an epigenic o r i g i n are characterized by enhancement of metal l e v e l s i n surface horizons (Bradshaw et a l , 1973). Several zones of Cu - Mo mineralized bedrock within the Capoose Lake granodiorite, north, east and south of Capoose Lake are marked by s o i l Cu and Mo anomalies. Heterogeneity of processes operating short distances apart r e s u l t s i n a variety of anomaly geneses. 'Boggy areas and seepage zones are prone to hydromorphic enrichment. Metal accumulation follows scavenging by organic matter and amorphous Fe oxides. Hydromorphic dispersion appears*responsible for many of the Cu and Ho s o i l anomalies within the bounds of the North Anomaly, p a r t i c u l a r l y 239 near seepage zones and along Swannell Creek. However scavenging i s not an important factor i n d r i e r areas between creeks, p a r t i c u l a r l y where overburden i s thin and l o c a l l y derived. Trace elements enter the drainage network following erosion of stream banks, and following inflow of subsurface and ground waters. Pathways from s o i l s to streams are obscure because of the large size of the catchment, and because of v a r i a b i l i t y within s o i l s a t t r i b u t a b l e to s o i l forming processes, degree of water saturation and sample texture. At the North Anomaly, mechanical erosion appears secondary i n importance i n view of the marked change i n mechanics of trace element retention i n streams compared to s o i l s (Fig 20). Although organic matter scavenging leads to Cu and Mo enhancement i n seepages east of Swannell Creek, scavenging by organic matter or amorphous Fe oxides does not r e s u l t i n Cu accumulation to anomalous l e v e l s i n Swannell Creek. The amorphous Fe oxide f r a c t i o n of stream sediment i s associated with 40 to 501 of the Cu, and l e s s e r amounts of Mo and Zn. This percentage of the • t o t a l 1 metal content i s twice that associated with the same f r a c t i o n i n s o i l s ; despite the fact amorphous Fe oxides comprise approximately the same proportion of both types of sample. Greater association of trace elements with amorphous Fe oxides probably r e f l e c t s a large i n f l u x of trace metals to the stream in* subsurface or ground waters. Such a genesis i s supported by enhanced contents of readily-soluble Zn i n s o i l s adjacent to the creek. . Relatively large amounts of Zn, Fe, and Mn are li b e r a t e d e a s i l y from Swannell Creek sediments above Line 1, and are 240 probably derived from Takla volcanic rocks above the contact with the Capoose Lake granodiorite. Dispersion trains of Hn and Zn are p a r t i c u l a r l y noteworthy because of s t r i k i n g changes in the e f f i c i e n c y of the hydroxylamine hydrochloride extraction approaching the outer bounds of the North Anomaly. „ Although Hn and Zn dispersion t r a i n s are longer than these of Cu and Ho, a l l decay to background values i n -80 mesh fractions prior to reaching Capoose Lake. Metal l e v e l s of Swannell Creek below Line 2 are notably lower than those within the confines of the North Anomaly. This r e l a t i v e impoverishment i s probably caused by mixing anomalous sediment with metal-poor sand derived from g l a c i a l deposits near the lake. However Swannell Creek sediment i s also Cu-rich beside Capoose Lake. In t h i s region, Cu accumulation proceeds by way of organic matter scavenging, and i s believed r e l a t e d to groundwater emergence near the lake. Metal enhancement i s also associated with seepage water and sediment around lake margins (Tables XXV and XXVIII). Consequently groundwater can be expected to provide s i g n i f i c a n t inputs of metal along the f l o o r of Capoose Lake. Metals are dissolved by groundwater passing over mineralized bedrock at the North Anomaly and elsewhere i n the watershed, and are transported beneath g l a c i o f l u v i a l deposits to the lake. Because hydromorphic anomalies are numerous within the confines of the North Anomaly, p a r t i c u l a r l y along break i n slope environments, hydromorphic anomalies might also be expected i n s i m i l a r topographic positions along the lake f l o o r . Although metal content and Eh - pH character of solutions along 241 the lake water - sediment interface are unknown, groundwater emergence appears to favour deposition of trace elements, probably as a conseguence of entering a more oxidizing lake environment, and active scavenging by amorphous Fe oxides and other sediment f r a c t i o n s . The North Anomaly occurrence l i e s only 2 to 3 km from Capoose Lake. Despite t h i s r e l a t i v e l y short distance, anomalous trace metal dispersion t r a i n s are not prominent features along Swannell or Bio Creeks. S i m i l a r l y , anomalous dispersion t r a i n s are not observed along main streams draining other mineral occurrences near the lake, i n -80 mesh fractio n s . t Although -80 mesh stream sediment or s o i l f r a c t i o n s are poor in Cu, Zn and Mo r e l a t i v e to nearshore or more c e n t r a l l y c o l l e c t e d lake sediments, mechanical inputs entering i n the form of suspended s i l t and clay minerals are important. Data for Capoose and Swannell Creeks; and 5 positions within Capoose Lake (Table XXVI) indicate s i l t and clay fr a c t i o n s are usually metal-rich by factors up to 43X the -80 mesh values (Pb i n Capoose Creek sediment) A Cu content of 1000 ppm i n the clay fract i o n of capoose Creek sediment greatly exceeds the 28 ppm (33X) -80 mesh content. The 1000 ppm l e v e l also greatly exceeds concentrations of comparable f r a c t i o n s i n an adjoining delta sediment (ID -748), but i s lower than a value of 1500 ppm in'deeper parts of the lake (ID - 173). The l a t t e r sample contains 50% more Cu, suggesting that i f the clay f r a c t i o n was o r i g i n a l l y transported from Capoose Creek, additional metal must be introduced by groundwater at the present locat i o n . However Cu content of the 242 clay f r a c t i o n i s s i m i l a r to a 1200 ppm content near the South Zone, a second possible source of trace elements. Because metal contents i n s i l t and clay fr a c t i o n s of samples 235 and 288 taken between the South Zone and Capoose Creek are lower than at both sources, i t i s unlikely Capoose Creek inflow i s the p r i n c i p a l control on metal-accumulation i n the southwest quarter of the lake. Clay mineral i d e n t i f i c a t i o n i s not diagnostic on t h i s point because c h l o r i t e and k a o l i n i t e are found hoth i n Capoose and Swannel Creek sediments, and adjacent to the South Zone. However i l l i t e , vermiculite, and k a o l i n i t e characterize samples between the delta and the mineralized zone. Relative importance of suspended or dissolved material inflowing i n streams i s uncertain. Close correspondance of Cu, Zn and Mo-rich 'water* and the Capoose Creek d e l t a , and enrichment factors to 43X in clay f r a c t i o n s compared to -80 mesh suggest introduction of metal-rich fi n e s suspended in stream i s an important factor. These fr a c t i o n s are subsequently deposited i n a zone 200 to 600 m from the mouth of the creek. However near Capoose Creek large quantities of metal-poor sand greatly reduces Cu # Zn;-Ho, Fe and Hn values along the northern end of traverse l i n e s i n the west compared to the south or lake outflow region. Values of Cu and Zn i n the east are analogously diminished by entry of Swannell, Chatupa and Asarco Creeks. In addition to depositing a delta, these creeks may also contribute large quantities of sand to deeper parts of the lake as a consequence of slumpinq of d e l t a i c foreset beds or t u r b i d i t y currents, by a mechanism si m i l a r to that reported for F a y e t t e v i l l e Green Lake (Ludlam, 1974). 243 Dispersion of Pb and Zn from Green Lake area s o i l s to Capoose Creek i s rapid because most of the s o i l anomalies l i e above t r e e l i n e where weathering, erosion, and mechanical dispersion are rapid. Acid surface and ground waters also promote rapid solution of Pb, Zn, Cu and Ag from mineral showings, bedrock; and overburden. Trace elements are deposited where conditions are favourable, p a r t i c u l a r l y near breaks i n topographic slope beside Capoose Creek. Insoluble minerals accumulate where stream velocity diminishes. By contrast, vigorous hydromorphic dispersion i s ended by amorphous Fe oxide and organic matter scavenging, p a r t i c u l a r l y i n boggy environments. Despite the fact that Pb - Zn - Cu - Ag occurrences of the Fawnie Range are a c t i v e l y weathering and rapidly eroding, s o i l and stream sediment anomalies may l i e too far away (5 to 13 km) to have a pronounced e f f e c t on trace metal d i s t r i b u t i o n s within Capoose Lake. As distance between bedrock sources and the lake increases, chances are greater that metal-rich stream sediment w i l l become fi x e d i n bogs or at topographic i n f l e c t i o n s . Moreover, because the Fawnie Range near Capoose Lake i s drained by 4 streams-similar i n size to Capoose Creek, mechanical d i l u t i o n of anomalous stream sediment dispersion t r a i n s o r i g i n a t i n g i n the mountains by barren material before reaching Capoose Lake i s l i k e l y i n -80 mesh fr a c t i o n s . Though metal-rich f i n e r f r a c t i o n s may be transported greater distances, potential anomalies r e f l e c t i n g mineralized bedrock can be missed by analyzing only -80 mesh fra c t i o n s . Trace element concentrations associated with s i l t and clay 244 frac t i o n s near Green Lake are unavailable. However at the Capoose Creek inflow to Capoose Lake* the Pb content i s 7X (56 ppm) and 43X (339 ppm) greater i n s i l t and clay f r a c t i o n s , respectively, than the 8 ppm value of -80 mesh material. S i m i l a r l y ; the clay f r a c t i o n of Swannell Creek sediment i s enriched 8X the -80 mesh value. within the Capoose Creek delta, Pb content of the clay f r a c t i o n i s r e l a t i v e l y low. In comparison samples 235 and 288 are r e l a t i v e l y Pb-rich, declining with distance from Capoose Creek from 339 ppm to 108 and 200 ppm; respectively. Influence of Cu - Mo showings on Pb level s appears i n s i g n i f i c a n t , i n view of the r e l a t i v e l y low Pb values in s i l t and clay near the South Zone. Zn content follows Cu, Mo, Fe and Mn d i s t r i b u t i o n s and i s probably related to Cn - Mo sulphide concentrations; Within the catchment, a variety of mechanical and hydromorphic processes within s o i l s and streams promote trace element dispersion towards the lake. Referring to the Allan and Timperley (1974) model, trace elements enter Capoose Lake as c l a s t i c bed loads or i n the form of suspended fines c a r r i e d by streams; associated with d e t r i t a l organic matter, and i n surface or groundwater solutions. Because of experimental d i f f i c u l t i e s i n sample c o l l e c t i o n and complexity of limnological processes, r e l a t i v e importance of each input type i s uncertain. Within the lake, trace elements associated with mechanically-introduced s i l t and clay e q u i l i b r a t e with lake water under Eh - pH conditions prevailing on the lake f l o o r , and metals may be released to overlying water. A l t e r n a t i v e l y , trace elements may be deposited from lake water or inflowing 245 groundwater, and accumulate to abnormally high levels. Consequently, trace metal d i s t r i b u t i o n s i n i t i a l l y c o ntrolled by factors a f f e c t i n g sediment deposition, are modified, and depending on strength of leaching or enrichment processes, lake sediment anomalies r e f l e c t i n g stream inflow may be obscured completely. -Anomalies r e f l e c t i n g hydromorphic enrichment are more e a s i l y i d e n t i f i e d than anomalies r e f l e c t i n g mechanical enrichment. Trace elements are deposited from emerging groundwater because Eh - pH conditions i n the lake are probably d i f f e r e n t from those of groundwater. However i f a large percentage of trace elements f a i l to deposit immediately after groundwater emergence, they may migrate from points of entry and deposit more evenly across the lake f l o o r . In extreme cases, t h i s process leads to uniform dispersal of trace elements across the lake f l o o r , and masks the re l a t i o n s h i p between lake anomalies and mineralized bedrock via groundwater dispersion. Base metal enrichment in Capoose lake characterizes two elongated zones p a r a l l e l to and within 150 m of the north and south lake shores, coinciding with the base of the nearshore slope. Hetal enrichment apparently proceeds via scavenging of trace and minor elements by c r y s t a l l i n e Fe oxides (Ho, Fe), amorphous Hn oxides (Zn, Hn), and amorphous Fe oxides (Cu, Zn, Ho). Though not as common a feature, weaker extractants also may dissolve a larger f r a c t i o n of Cu and Zn from samples co l l e c t e d near the break i n slope than elsewhere i n the lake. Concentration of r e a d i l y soluble Cu and Zn i n proximity to South Zone and North Anomaly occurrences i s p a r t i c u l a r l y noteworthy. 246 and indicates more metal i s entering the lake near known showings than elsewhere along the lake f l o o r , • Poor contrast between peaks of the * double peak d i s t r i b u t i o n * and nearshore or basinal concentrations among • t o t a l * determination data i s caused by metal enhancement associated with organic matter and s i l i c a t e residues, i n positions other than near the base of slope. Hithin s i l i c a t e residues; trace metal l e v e l s are greater near the centre of the lake than nearshore. In comparison, organic matter accumulates trace elements i n basinal sediment i n the east, and i n basinal and nearshore-sediments i n the west. Influence of South Zone sulphides, and d e l t a i c sedimentation associated with Capoose Creek i s probably more important i n c o n t r o l l i n g trace metal d i s t r i b u t i o n s than compositional parameters. Cu, Zn, and Mo accumulation near the South Zone represents the main Capoose Lake anomaly. Although well defined among-•total* determination data, anomaly contrast i s greatly improved among data of several of the sequential extractions, p a r t i c u l a r l y among data from the hydrogen peroxide attack. In that case; a spike-like Mo anomaly i s found within 50 m of s h o r e . A l t h o u g h the form of the Mo in the sample i s unknown, anomaly genesis i s believed related to mechanical disintegration of mineralized bedrock nearshore. However metal enrichment further into the lake near the base of slope r e f l e c t s hydromorphic processes. In t h i s respect, metal accumulation i s s i m i l a r to other metal-rich zones of Capoose Lake. The North Anomaly i s not r e f l e c t e d d i r e c t l y by Cu, Zn, and Mo lake sediment anomalies. Metal concentrations i n the lake 247 Table XXXTV , Comparison of trace element content (ppm) of Capoose, Fish and Portnoy Lake area lake sediment, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid digestion Capoose Lake F i s h Lake Portnoy Lake Threshold 245 75 37 Cu Hean 70 38 29 Range 39-135 27-50 25-33 Threshold 930 50 80 Zn Hean 250 30 55 Hange 130-480 23-39 48-65 Threshold 11.3 1.3 0.80 Fe Hean 3.2 0.79 0.47 % Range 1.7-6.0 0.61-1.0 0.36-0. Threshold 19100 250 215 Hn Hean 1300 150 80 Range 340-5000 115-190 48-130 Threshold 38 Pb Hean 12 Range 6.8-21 Threshold 88 38 49 Ho Hean 11 7.6 16 Range 4.3-30 3.4-17 9.8-29 Threshold 23.1 60.9 65.6 OH Hean 6.7 34.7 44.6 X Range 3.6-12.5 26.2-46.0 36.8-54 Number of samples 127 22 12 mean - calculated for a lognormal d i s t r i b u t i o n range - lognormal mean + 1 standard deviation threshold - >(mean + 2 standard deviation i n t e r v a l s ) 248 downslqpe of the mineral shoving are below average for base of slope environments'in Capoose lake. Low values may r e f l e c t low grades of Cu - Mo sulphides i n the source area; excessive distance of the mineral showing from the lake; r e l a t i v e i n s o l u b i l i t y of metals at the source; immobilization of trace elements along dispersion paths; or other factors. However d i l u t i o n by metal-poor sands of Capoose and Swannell Creeks i s apparently the main factor operating against anomaly d e f i n i t i o n i n -80 mesh f r a c t i o n s . High sand contents also diminish the scavenging a b i l i t y of the sediment. Relative absence of scavenging agents might also explain the high content of trace elements associated with bottom water i n t h i s portion of the lake. ' Seguential extraction studies suggest scavenging of Cu, Zn, and Ho by amorphous Fe oxides i s the predominent mechanism by which these elements are extracted from solution (compare Table XVII with Tables XVI and XVIII; also Figs 14 to 17, 20 and 21). This sediment f r a c t i o n i s presumed to be most abundant i n recent sediment near the sediment - water interface. Its surface area should also be greater near surface than at deeper i n t e r v a l s i n the sediment where loading i s greater, water content i s lower, and aging of pr e c i p i t a t e s i s greater. Trace metal scavenging should therefore be a c h a r a c t e r i s t i c s u r f i c i a l sediment property, and should diminish with depth into sediment, p a r t i c u l a r l y on passing from oxidized to reduced environments. However solutions migrating through sediment at greater depths night encounter rapidly changing Eh environments, and deposit trace and minor elements where conditions are favourable. 249 Although metal accumulation i s predicted to characterize s u r f i c i a l sediment; only Mn contents are enhanced i n s u r f i c i a l sediment (Table XXXIII). In comparison* concentrations of Cu, Zn, Fe and Mo are approximately constant with depth, apparently sensitive only to textural variations. In contrast to general'trends, Cu, Zn and Mo contents of a core (core 293, Table XXXIII) near the South Zone showing increase 12X, 4X, and 33X, respectively, from surface to the deepest core sample. For Cu and Mo, t h i s depth trend i s outstanding i n view of the 42 ppm and 3 ppm values at surface, l e v e l s well below average contents of these metals i n Capoose Lake sediment (Table XXXIV). Moreover, values at depth exceed most s u r f i c i a l sediment concentrations. Because the core sta t i o n l i e s i n r e l a t i v e l y shallow water (Table XXXII) near angular granodiorite boulders f r o s t heaved from the South Zone showing, and samples have a high content of sand, metal enrichment i s probably r e f l e c t i n g mechanical dispersion from the South Zone. Fe and Mn concentrations show les s variation with depth into sediment than with position along the lake f l o o r . Further* Fe and Mn leve l s are enhanced i n d i f f e r e n t parts of the lake, with Mn contents commonly enriched at greater lake depths than Fe; A model can be proposed to explain the r e l a t i v e d i s t r i b u t i o n of Fe and Mn i n s u r f i c i a l sediment. Both elements are introduced as solutes i n groundwater, p a r t i c u l a r l y along the base of the nearshore slope* Hydrated Fe oxide p r e c i p i t a t i o n i s more rapid than that of Mn (page 387, Garrels and C h r i s t , 1965), and consequently Mn i s dispersed greater distances from zones of 250 emergence. Abundance of Mn oxides at depth probably indicates oxygen i s p l e n t i f u l along the lake f l o o r . Otherwise Mn deposition would await more oxidizing conditions, and the element would accumulate i n shallower water sediments.. S o l u b i l i t y of Fe, Hn, and trace elements i n various seguential extraction reagents provides evidence of the mechanics of trace element retention i n lake sediments., For example, c r y s t a l l i n e Fe oxides comprise 40 to 60S of the ' t o t a l * Fe content. Over'50% of the Mo content appears associated with t h i s phase whereas Mn content of the c r y s t a l l i n e Fe oxide phases constitutes only 5 to 1035 of the • t o t a l " Mn content {Fig 17). However 40 to 50% of the Mn i s readily soluble i n hydroxylamine hydrochloride whereas Fe, as well as Cu, Zn, and Mo are only dissolved i n minor amounts. Consequently, with the exception of Mo, approximately half of the Cu and Zn i s associated with the Fe and Hn content*of Capoose Lake sediment. By contrast, amorphous Fe oxides, comprising 15 to 2556 of the ' t o t a l * Fe content, appear associated with 30 to 46ft of the Cu and Zn concentrations (Table XVII). C r y s t a l l i n e Fe oxides are apparently able to scavenge only Ho from ground and lake water whereas Hn i s e s s e n t i a l l y excluded, to accumulate in a form which i s soluble i n neutral ammonium acetate, a c i d i f i e d d i s t i l l e d water and hydroxylamine hydrochloride. Although amorphous Mn oxides are abundant and probably have an extremely large surface area, t h i s sediment component i s apparently able to scavenge only minor amounts of Zn. By contrast,- amorphous Fe oxides appear to control Cu, Zn and to a lesser extent Mo v a r i a b i l i t y . However when compared to 251 stream and s o i l samples, lake sediment i s composed of a s i m i l a r proportion of amorphous Fe oxides. Hence metal accumulation associated with t h i s sediment component r e f l e c t s either a greater scavenging a b i l i t y of lake sediment amorphous Fe oxide phases compared to corresponding stream and s o i l phases, or a greater a v a i l a b i l i t y of trace elements i n lakes compared to the catchment. A t h i r d p o s s i b i l i t y involving expulsion of trace elements on aging of amorphous oxides, can be suggested because c r y s t a l l i n e Fe oxides are r e l a t i v e l y impoverished i n Cu and Zn concentrations, and because c r y s t a l l i n e Fe oxide phases are probably derived by aging of amorphous phases. Despite f l u c t u a t i o n s i n sediment texture and composition, regression analysis suggests a large proportion of the trace element v a r i a b i l i t y can be explained i n terms of the ' t o t a l * Fe and organic matter content. .Successful application of regression analyses i s unexpected i n view of r e s u l t s from the sequential extraction study. These showed that the quantity of Cu, Zn and Ho associated with organic matter i s r e l a t i v e l y low, and amorphous or c r y s t a l l i n e Fe oxides appear to accumulate these elements. Correlation of Cu and Zn l e v e l s with oxalate e x t r a c t a b l e F e i s strong whereas other Fe fractions release these metals i n a more random fashion compared to ' t o t a l * values. In view of the f a c t only 21% of the ' t o t a l * Fe appears to control an average of 31 and 45% of the Cu and Zn v a r i a b i l i t y of basinal sediments (Table XVII), respectively, whereas 40 to 60% of the Fe released by d i t h i o n i t e i s r e l a t i v e l y i n e r t towards these elements', c r y s t a l l i n e Fe oxides appear to d i l u t e the • t o t a l * Fe content, a factor which should diminish a p p l i c a b i l i t y 252 of the regression analysis. By contrast, strong c o r r e l a t i o n of Fe and Mo r e f l e c t s the fact that c r y s t a l l i n e Fe oxides appear to concentrate Mo. ~ Results of the Capoose Lake study i l l u s t r a t e the complexity of processes which a f f e c t trace metal l e v e l s within a s i n g l e lake. The next section describing trace element d i s t r i b u t i o n s i n Fish and Portnoy Lakes, examples of an organic-rich, and Fe and Mn oxide-poor limnological environment, further i n d i c a t e s complexities to be expected i n evaluating lake sediment geochemical data. For regional surveys which reguire sampling of a wide variety of lake types associated with many geologic units and topographic environments, prediction of trace metal v a r i a b i l i t y by regression analysis i s not to be expected unless a fortuitous set of circumstances p r e v a i l . although samples of sim i l a r appearance, texture and composition should be separated on the basis of phy s i c a l l y recognizable properties, chemical properties of sediment fractions should also be taken i n t o account prior to application of regression analysis. 5 . . Summary Abnormally high concentrations of Cu, Zn, Mo and Pb enter Capoose Lake attached to c l a s t i c p a r t i c l e s , or dissolved i n stream or ground water. Metals commonly are deposited near points of inf l o w a n d can accumulate to abnormally high l e v e l s . However accumulation of trace elements can be obscured by deposition of sand-rich sediment, and by limnological processes r e d i s t r i b u t i n g and homogenizing trace metal contents. Influx of metal-rich groundwater apparently r e s u l t s i n 253 narrow zones of trace element enrichment coinciding with the base of the nearshore slope, p a r a l l e l to the north and south shores of the lake. Although a f r a c t i o n of the inflowing metal i s transferred to other parts of the lake, i n contrast to stream inputs, metal accumulation zones associated with groundwater inputs are prominent. However groundwater enrichment zones are subject to d i l u t i o n by coarse c l a s t i c sediment~associated with stream inflow, or to enrichment by a c t i v e l y weathering mineralized zones l y i n g within or close to the lake. The most prominent Cu - Zn - Mo anomaly i n Capoose Lake, i n the southwest beside the South Zone, apparently has a mechanical o r i g i n nearshore. However further i n t o the lake hydromorphic dispersion i s important i n anomaly genesis. By contrast, enrichment of trace elements i n lake sediments downslope of the North Anomaly i s weak, and metal leve l s along the base of slope are only s l i g h t l y enhanced compared to values near the middle of the lake. Failure of Cu, Zn and Mo to form a well-defined anomaly appears related to d i l u t i o n by metal-poor sand deposited by Capoose and Swannell Creeks. Trace metal content of sediment near the middle of the lake i s r egionally anomalous, though leve l s are 20 to 80% lower than peak values associated with the base of slope environment. Enrichment r e f l e c t s 1 u n i f o r m dispersal of inputs associated with streams and groundwater, by limnological processes which a f f e c t c l a s t i c sedimentation and metal deposition from hydromorphic solutions. In some lakes, l i m n c l o g i c a l processes may be able to homogenize the trace metal content of sediment i n deeper parts of the lake (Coker and Nichol, 1975). However within Capoose 2 5 4 lake limnological factors are not able to mask zones of metal accumulation near points of inflow. 255 C. Fish and Portnoy Lakes 1. Introduction The Fish and Portnoy Lakes area (22 lakes) i s associated with 6 metal-rich lake sediment samples, enhanced i n one or more of Zn, Pb, Mo and Cu, co l l e c t e d on the basis of 1 sample per lake. Concentrations of 340 and 130 ppm Zn (2 separate lakes), 10 ppm Pb (3 lakes) , 25 (Portnoy Lake) and 14 (Fish) ppm Mo and 53 (Fish) ppm Cu, however, are only above average (x+o-) or barely exceed regional thresholds of 237 ppm Zn, 6 ppm Pb, 9 ppm Mo and 95 ppm Cu. Only trace element d i s t r i b u t i o n s around Fish and Portnoy Lakes are examined i n the present study. A prominent Cu - Mo - Zn mineralized zone (Portnoy Zone) l i e s beneath the h i l l b e t w e e n the two lakes (Fig 57). Mineralized bedrock i s drained by a small creek flowing southward (Portnoy Creek, u n o f f i c i a l name) which enters a regionally prominent bog (Fish Lake bog) east of Fish Lake. Several small streams to the southwest also l i e downslope of the sulphide occurrence. A l l streams and seepages draining into Fish and Portnoy Lakes were sampled to estimate quantities of trace elements i n streams and/or groundwater flowing into each lake. The largest stream of the region; entering at the western end of F i s h Lake, does not drain any mineralized areas. Other streams flowing into Fish Lake are small and are l e s s than 1000 m long.. By contrast, no streams flow into Portnoy Lake. Samples of organic-rich overburden or bogs surrounding the lake were co l l e c t e d i n addition to lake and stream samples. 2. Description of the study area 256 \*1 WASKETT LAKE PORTNCn >F ISH U fo CHUTANLLJI ANOMALY L 3 M ILES 5000 METERS J CONTOUR INTERVAL 500 FEET ( 1 5 3 METERS) A MOUNTAIN SUMMIT — — S T R E A M . AREAS OF SULPHIDE CONCENTRATIONS SHADED F IGURE 5 7 : OFF IC IAL AND UNOFF IC IAL LOCALE NAMES OF THE F I SH LAKE - PORTNOY LAKE AREA 257 a. Geology and mineralization (Fig 58) The Fish•- Portnoy Lake area o v e r l i e s the contact between a major northwestward-trending belt of sedimentary and volcanic rocks of Late T r i a s s i c or Cretaceous age (Hazelton volcanics) and a g r a n o d i o r i t i c batholith of Late Jurassic age (Tipper, 1961). Also intruded into the layered volcanics are a series of dikes and s i l l s of a c i d i c to intermediate composition-, These may be part of t h e l a r g e r intrusion or represent a separate phase of plutonism. The Portnoy Zone i s underlain by a series of volcanic and sedimentary l i t h c l o g i e s consisting of a r g i l l i t e , g uartzite, conglomerate-, and volcanic sediments such as t u f f , agglomerate and breccia. A massive andesite flow unit also occurs within*the layered sequence. The study area was glaciated along a 020° direction and t i l l overburden averages 6 to 20 m deep. Low-lying areas are covered by extensive g l a c i a l and g l a c i o f l u v i a l deposits and bedrock exposures are rare. Near the mountains around Portnoy Lake, overburden i s more l o c a l l y -derived;, and has~a residual o r i g i n at higher elevations. Mineralized-^zones are located i n an a l t e r a t i o n halo along the northern contact of the granodiorite batholith (Smith, 1972). Two regions, the Portnoy Zone and the Chutanli Anomaly (Fig 57), have been outlined. The Portnoy Zone, centre of the present study, i s associated with h o r n f e l s i c a r g i l l i t e s and s i l i c i f i e d fragmental rocks. The andesite flow unit acted as a b a r r i e r and was apparently impermeable to mineralizing solutions. Grades of mineralized bedrock are greatest where proximity of the andesite to the batholith has prevented excessive dispersion of f l u i d s derived from the pluton., The 258 ( 3 M I L E S i \ 5000 METERS _J CONTOUR INTERVAL 500 F EET ( 1 5 3 METERS) A MOUNTAIN SUMMIT — S T R E A M lllll GRANODIORITE — PROBABLE FAULT ; X 3 - . V PYROCLASTICS GEOLOGIC CONTACT V-yL-i MASSIVE AMDESITE MINERAL SHOWING ' BIIIIARGILLITES, CONGLOMERATE, QUARTZITE F IGURE 5 8 : GEOLOGICAL MAP OF T H E F I S H LAKE - PORTNOY LAKE AREA ( A F T E R R I O T I N T O , 1 9 6 9 ) 259 mineral occurrence, consisting of a guartz - sulphide stockwork within 400 m of the i n t r u s i o n , averages 0.03% Cu and 0.03% Mo. Sulphide minerals, i n order of abundance are py r i t e , chalcopyrite, molybdenite, and sphalerite. The Chutanli Anomaly l i e s i n an area of extensive overburden 5000 m to the east of. the Portnoy Zone. Anomaly outline, defined by aeromagnetic, IP, and s o i l geochemical surveys, o v e r l i e s an area 0.6 km2 (600 m X 1000 m) . From geological mapping and d r i l l logs, bedrock i s composed of meta-volcanic r h y o l i t e , andesite, and feldspar porphyry, intruded by a coarse grained granodiorite. Disseminated p y r i t e , up to 15% by volume of the rock* accounts for the IP anomaly. Cu concentrations are consistently of low tenor at 0.02 to 0.07%. Chalcopyrite occurs as small masses, disseminations, and along guartz veins and st r i n g e r s . Other sulphide minerals associated with stringers are bornite, sphalerite, and molybdenite, i n trace amounts. b. Topographic setting and drainage Fish Lake, at 1130 m, l i e s along the base of the western side of the Nechako Range (Fig 57). The lake overlies extensive deposits of sands and gravels. Eskers, 3 m high, l i e adjacent to the north and south shore of the lake. Bogs form as a consequence of beaver dams across the lake outlet and completely enclose the lake. Slopes on the north side of Fish Lake (1 i n 8)- extend f a i r l y continuously from the edge of the boggy region (1160 m) to the'mountain summit (1460 m). The presently known extent of the Portnoy Zone l i e s upslope at 1350 m (Fig 57). In 260 the south, topography f l a t t e n s several meters above lake l e v e l . Although geology underlying the lake i s unknown, bedrock i s believed to be the granodiorite i n t r u s i o n , and contact with Hazelton units l i e s beneath g l a c i a l and c o l l u v i a l material on the mountainside at about 1200 m in elevation. Portnoy Lake (1340 m) l i e s along the axis of the Nechako fiange along a »U'-shaped valley. The lake i s surrounded by a prominent bog (Portnoy Lake bog), and has no stream inputs. However, a f a i r l y large stream drains the lake and a prominent spring enters the outflowing creek from the east. G l a c i a l and c o l l u v i a l deposits are thick along the Portnoy lake v a l l e y , and appear to conceal the contact between andesite and p y r o c l a s t i c units. At higher elevations, overburden i s comprised of residual and c o l l u v i a l material. Slopes are steeper (1 i n 4) than near Fish Lake, but mountains r i s e only to 14 30 and 1460 m i n the west and east, respectively. The remainder of the study area i s overlain by a large number of small lakes. Stream drainage i s poorly developed or disorganized, and swampy ground i s prominent at lower elevations and around small lakes. Streams are small and flow along shallow valleys, cutting g l a c i a l or c o l l u v i a l deposits prior to merging into lowlying bogs. Sediment i s composed of sands and c l a s t i c forms of organic matter, and a l l u v i a l deposits are rare. c. S o i l s and vegetation Three major parent materials are recognized: g l a c i a l and g l a c i o f l u v i a l deposits* cclluvium, and residual material near the tops of the mountains, p a r t i c u l a r l y east of Portnoy Lake. 261 C o l l u v i a l and g l a c i a l overburden are mostly well-drained and associated with podzols and bruniscls. Begosols and brunisols develop on residual material. Pedogenesis i s controlled by rates of mechanical disintegration of bedrock and downslope c o l l u v i a l or sheetwash movement. Gleyscls and organic s o i l s are common i n water-saturated or boggy environments near F i s h and Portnoy lakes. Mature stands of lodgepole pine are c h a r a c t e r i s t i c of well drained areas* Black spruce are found l o c a l l y along stream channels and are p a r t i c u l a r l y abundant at the periphery of bogs. Near lakes and within bogs, vegetation consists of grasses, mosses, and sedges. d. Lake descriptions Fish Lake has a maximum length, width, and depth of 400 m, 200 m and 2.5 m, respectively, and i s wider i n the northwest than i n the southeast. Lake shape resembles a f i s h and i s controlled by beaver dams across the ou t l e t . Although a boggy region completely surrounds the lake, the bog i s p a r t i c u l a r l y extensive i n the east. In t h i s region, c l a s t i c sediment of small streams i s trapped prior to reaching the lake. Nevertheless; lake sediment samples may contain appreciable sand concentrations derived from pre-lake g l a c i o f l u v i a l deposits, p a r t i c u l a r l y at-deeper sampling i n t e r v a l s . In the west, coarse c l a s t i c inputs are provided by a rap i d l y flowing creek, 0.7 m wide and 0.2 m deep, which has formed a minor delta extending up to 15 m into the lake. By comparison, Portnoy Lake i s only 120 m long, 90 m wide and 1 m deep. Bogs completely surround the 262 pond and, in vies of the absence of inflowing streams, the lake i s fed exclusively by groundwater. A slow-moving stream-, 0.7 m wide and 0.1m deep, serves as the outlet. Sediment i n both lakes i s composed of partly decayed vegetation s i m i l a r to well-humified bog material. Consistency ranges from firm to soupy, and the o l i v e green (5r4/4) colour of the sediment s a t i s f i e s the c r i t e r i a f o r c l a s s i f i c a t i o n of the sediment as gyttja (Timperley and Al l a n , 1974). In F i s h Lake, sand introduced by the western creek i s diluted by organic matter. Consequently, sediment near the inflow bay v i s u a l l y appears i d e n t i c a l to organic-rich oozes at the opposite end of the lake which i s completely surrounded by bogs. Organic matter comprises an average 35% and 45% of the sediment composition by weight i n Fish and Portnoy Lakes, respectively, but may att a i n 60 or 70% l e v e l s l o c a l l y (Figs 65 and 69). Lake water i n proximity to shore i s 0.3 to 0.6 m deep and shallows or beaches are absent. Lake banks are held together by a root matte of bog vegetation. Large aquatic plants are numerous, and plant remains or roots are invariably sediment constituents. Sediment i n Portnoy Lake emits the c h a r a c t e r i s t i c odour of hydrogen sulphide. Lake water shows a 7°C decline i n temperature from surface to the bottom of Fish Lake whereas i t remains approximately constant i n Portnoy Lake. Temperature v a r i a b i l i t y froia day to day i s great, i n d i c a t i n g overturns are a common occurrence i n both lakes, depending on wind velocity and storm frequency. pH i s approximately constant and neutral i n both lakes (Table XXX). Fish Lake i s probably dystrophic, containing an average of 11 263 ppm bicarbonate, 3 ppm sulphate (Table XX), and 9 ppm dissolved oxygen. Portnoy Lake contains an average of 19 ppm bicarbonate and 22 ppm sulphate and, i n view of the strong odour of hydrogen sulphide i n sediment and permeating through the lake water, Portnoy Lake i s probably eutrophic. ew Sample c o l l e c t i o n C o l l e c t i o n of lake sediment and water i s described i n Chapter 4 and areas of detailed studies around the Portnoy Zone are summarized on Fig 59.; Two s o i l traverses (Lines 6 and 7) crosscut s o i l Cu - Mo anomalies (Fig 60) and l o c a l topography upslope of Fish and Portnoy Lakes. Stream samples were taken along Portnoy Creek as well as at inflow and onflow points around Fish Lake, and at the outflow of Portnoy Lake. Bog samples were c o l l e c t e d along lake banks to complete the survey. 3. Geochemical r e s u l t s a. Fish Lake 1. Geochemical dispersion towards Fish Lake S u r f i c i a l deposits i n the mountains or near the Portnoy Zone are comprised of residual or l o c a l l y derived colluvium, and bedrock i s exposed over 10% of the landscape surface. H e l l -drained g l a c i o f l u v i a l deposits are common downslope of 1300 m. Near the base of slope overburden i s water-saturated i n association with the Fish Lake bog. Cu, Zn and Mo contents of g l a c i a l deposits along Line 6 are r e l a t i v e l y low. Nevertheless Cu, Zn, and Mo are s l i g h t l y enriched i n podzollic and b r u n i s o l l i c s o i l s along the break of slope environment near FIGURE 59: SAMPLE LOCATIONS AT FISH AND PORTNOY LAKES DESCRIBED IN TEXT ASOILS, BSTREAM SEDIMENTS, OLAKE CORES l-O 265 •J 3 M I L E S t I 5000 METERS I CONTOUR INTERVAL 500 F EET ( 1 5 3 METERS) A MOUNTAIN SUMMIT - — STREAM H > 5 0 PPM F IGURE 60A: D I STR IBUT ION OF COPPER VALUES GREATER THAN 50 PPM VALUES IN SO I LS (COURTESY R J Q TlNTO) 266 | 3 M I L E S t I 5000 METERS | CONTOUR INTERVAL 500 F EET ( 1 5 ~ METERS) * MOUNTAIN SUMMIT - — STREAM I 1 P 5 0 PPM S >5 PPM F IGUREBOB: D ISTRIBUTION OF MOLYBDENUM VALUES GREATER THAN 5 OR 50 PPM IN SO I LS (COURTESY R I O T I N T O ) 267 1200 m (Fig 61). Cu, Mo and Mn are primarily held by amorphous Fe oxides i n t h i s region (Table XXXIX). In addition, metal enhancement i s t y p i c a l of gleysols or organic-rich horizons of the bog near Fish Lake. Cu and Mo l e v e l s of residual s o i l s upslope of the g l a c i a l deposits are 2X and 6X greater, respectively, and Mn values are s l i g h t l y greater, than are concentrations of these elements associated with g l a c i a l deposits near the break i n slope. Cu, Mo, and Zn enrichment i n s o i l s also r e f l e c t the Portnoy Zone. This zone i s indicated by a 40 ppn Mo anomaly (maximum value 100 ppm). The Mo anomaly also coincides with Cu and Zn enhancement up to 68 and 210 ppm, respectively. Metal l e v e l s near the mineralized zone and elsewhere at higher elevations commonly increase with depth, so that highest values are found i n the 'C horizon (Fig 61; Table XXXV). A large proportion of the ' t o t a l ' Cu, Zn and Mn content i s bound i n s i l i c a t e residues whereas Mo i s held by c r y s t a l l i n e Fe oxides. Large streams were not crossed by the s o i l traverse l i n e s . Consequently studies on metal transfer from s o i l s to streams sediments are unavailable. One major stream provides s i g n i f i c a n t quantities of sand inputs to the western h a l f of Fish Lake. However the creek does not erode any s o i l anomalies (Fig 60), and stream sediment i s not enriched i n Cu, Zn or Mo i n -80 mesh f r a c t i o n s . Although several small streams enter Fish Lake from the north, associated c l a s t i c inputs also are not metal-rich (Figs 62 to 64; Table XXIII). By contrast, some seepages downslope of the Portnoy Zone contain enhanced Cu and Zn l e v e l s i n water and sediment. In t h i s regard, i t should be T O P O F T H E C H O R I Z O N " B M H O R I Z O N Q F E E T . B F H O R I Z O N — A H H O R I Z O N h-4- -=n 1 B G H O R I Z O N L - H H O R I Z O N 5 0 0 M F I G U R E 6 1 A : V A R I A T I O N O F C O P P E R ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , L I N E S 6 A N D 7 T O P O F T H E C H O R I Z O N B M H O R I Z O N i w r . w i M I L . ^ „ B F H O R I Z O N A H H O R I Z O N | ^ H U U hbV BG H O R I Z O N L - H H O R I Z O N 500 M F I G U R E 6 1 B : V A R I A T I O N O F Z I N C L I N E S 6 A N D 7 ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E / - 8 0 M E S H F R A C T I O N , LANDSCAPE SURFACE 1000 VARIATION OF MOLYBDENUM JN DIFFERENT SOIL HORIZONS T O P O F T H E C H O R I Z O N B F H O R I Z O N B G H O R I Z O N BM H O R I Z O N AH H O R I Z O N L-H H O R I Z O N 2 4 0 0 F E E T 5 0 0 M F I G U R E 6 1 C : V A R I A T I O N O F M O L Y B D E N U M ( P P M ) I N S O I L S A C R O S S T H E L A N D S C A P E , - 8 0 M E S H F R A C T I O N , L I N E S 6 A N D 7 O Table XXXV Trace element content (ppm) of d i f f e r e n t s o i l horizons. Fish and Portnoy Lake area, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid attack L-H horizon Ah horizon Ae horizon B horizon Eh horizon Bf horizon Bm horizon c horizon Cn Threshold Moan Range 15 4.2 - 9.8 140 17 6.1-49 180 12 3.0 - 46 2 2 5 3 2 12 - 85 480 100 46 - 220 145 2 7 12 - 6 0 200 29 11 - 75 210 35 14 - 8 5 Zn Threshold • Mean Rsnje 75 26 16 - 4 4 . 1 0 5 20 8.8 - 47 2 7 19 16 - 2 3 160 5 0 2 8 - 9 0 1 5 0 5 0 3 0 - 9 0 185 55 3 2 - 1 0 0 145 44 24 - 80 85 37 2 5 - 55 ye % Threshold Mean Rtnga 1 . 7 . 0.5S 0 . 3 4 - l.o • 7.0 0.66 0 . 2 0 - 2.1 1.9 . 1.1 0.84 - 1.5 k.7 2.3 1.6 - 3 . 3 * . 5 2.3 1.6 - 3.2 4 . 7 2.5 • l.a - 3 . 4 4.6 2.1 • 1.5-3.2 5.1 2.2 1 . * - 3 . 3 Kn threshold 6 0 0 1 0 5 43 - 2 5 0 2800 1 3 0 28 - 6 0 0 175 6 5 42 - 1 0 5 9 2 5 175 75 - '•OO 5 2 0 0 I 6 5 3 0 - 9 2 0 610 160 8 5 - 3 1 0 7 3 0 1 9 0 9 5 - 370 7 1 0 180 9 0 - 3 6 O Xo Threshold Mean Rar.ga 28 4 . 4 1.8 - 1 1 165 7.8 1.7 - 36 195 4.1 0.6 - 28 110 6.8 1.7 - 2 7 1 3 0 1 3 4.0 - 41 80 5.9 1.6 - 22 120 6.5 1.5 - 28 6 5 5.1 1.4 - 18 Ku-ter of sanoles 8 19 5 115 12 5^ 55 1 9 mean - calculated for a lognormal d i s t r i b u t i o n range - lognormal mean + 1 standard deviation threshold - >(mean + 2 standard deviation i n t e r v a l s ) 272 noted that Portnoy Greek, also downslope of the Portnoy Zone, i s associated with metal-rich stream sediment, stream water and bank s o i l s . Although Portnoy Creek does not enter either lake, geochemical patterns are of i n t e r e s t because samples are from the same topographic setting as the f i s h and Portnoy Lake basins. At elevations above 1250 m, stream sediment of Portnoy Creek i s composed of guartz and feldspar sands coated by a black organic f i l m . Hear and within the Fish Lake bog, sediment consists of p a r t i a l l y decayed organic matter.: Below an elevation of 1200 m, water flow slows, eventually stagnates, and the creek ceases to be contained within a well defined channel. Cu and1Mo level s (Figs 62 and 63) in water and sediment are enhanced above property averages (Tables XXVII and XXIII) along the lower 1100 m, i n organic-rich (lower 600 m) and sand-rich (upper 500 m) s i l t samples. Consistently high values, up to 230 ppm Cu and 35 ppm Mo in sediment (property averages are 80 and 12 ppm, respectively) are associated with metal-rich stream water containing up to 7 ppb Cu and 50 ppb Mo (property averages are H and 5 ppb, resp e c t i v e l y ) . Seguential extraction studies suggest Cu and Ho accumulation by organic matter and amorphous Fe oxides leads to anomaly formation. However enhanced Cu content i n the s i l i c a t e residue of sample 1699 (Table XXIV) indicates mechanical inputs may also be important.. Ho enrichment i n bank s o i l s along Portnoy Creek l i e s d i r e c t l y downslope of the Portnoy Zone. Cu accumulation zones are not associated with Ho anomalies, but l i e along the eastern side of the creek, apparently unrelated to known mineralized 273 FIGURE 62A: PORTNOY CAMP COPPER (ppb) IN STREAM WATER TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND -4300- CONTOUR INTERVAL 100 FEET (31m) o less than 4 ppb — C R E E K S • 4 - 9 ppb LOCAL GRID COORDINATES © 10 - 26 ppb \ TRAVERSE LINES . ', ^ more than 26 ppb V SAf/PLE LOCATION • ; Z|QQQ F E E T , 1 , - , 1 1 0 0 0 M 1 V GEOCHEMISTRY OF FISH AND PORTNOY LAKES ON FIGS 65-6;69-7C Figures 62 to 71: Coded i n t e r v a l s represent: <(x); (x) to (x+<r) ; (x+<r) to (x+2<r); and >(x+2<r) FIGURE 62B: PORTNOY CAMP C O P P E R (ppm) IN S T R E A M S E D I M E N T S , - 8 0 M E S H F R A C T I O N T O P O G R A P H I C L E G E N D G E O C H E M I C A L L E G E N D -4300- CONTOUR INTERVAL 100 F E E T (31m) • less than 80 ppm CREEKS • 80 " 190 ppm LOCAL GRID COORDINATES @ 190 - 430 ppm TRAVERSE LINES ^ more than 430 ppm SAMPLE LOCATION 4 0 0 0 F E E T |! 1 0 0 0 M GEOCHEMISTRY OF FISH AND PORTNOY LAKES ON FIGS 65-6; 69-70 275 F I G U R E 6 2 C : P O R T N O Y C A M P COPPER (ppm) IN TOP OF THE B SOIL HORIZON. "80 MESH FRACTION TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND -4300- CONTOUR INTERVAL 100 FEET (31m) • l e s s t h Q n ^ P P m | • — CREEKS « 32 - 85 ppm ' I LOCAL GRID COORDINATES • 85 - 225 ppm j - TRAVERSE LINES • more than 225 ppm j SAMPLE LOCATION 4 0 0 0 F E E T "|| ' 1 0 0 0 M 1 i GEOCHEMISTRY OF FISH AND PORTNOY LAKES ON FIGS 65-6;69-70 FIGURE 63A: PORTNOY CAMP ZINC (ppm) IN STREAM WATER TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND -4300- CONTOUR INTERVAL 100 FEET (31m) ° l e s s 1 h a n 4 PPb — CREEKS • 4 - 7 ppb LOCAL GRID COORDINATES © 8 - 19 ppb >" • - TRAVERSE LINES ^ more than 19 ppb S A M P L E L O C A T I O N *}QQQ F E E T | i 1 IOOO M GEOCHEMISTRY OF FISH AND PORTNOY LAKES ON FIGS 65-6;69-70] FIGURE 63B: PORTNOY CAMP ZINC (ppm) IN TOP OF THE 'B' SOL HORIZON, -80 MESH FRACTION TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND -4300- CONTOUR INTERVAL 100 FEET (31m) • less than 50 ppm • CREEKS • 50 - 90 ppm LOCAL GRID COORDINATES • 90 - 160 ppm TRAVERSE LINES 6 more than 160 ppm SAMPLE LOCATION . , 4 0 0 0 F E E T | 1 1 0 0 0 M 1 GEOCHEMISTRY OF FISH AND PORTNOY LAKES ON FIGS 6-5-6,69-70 278 FIGURE 64A: • PORTNOY CAMP MOLYBDENUM (ppb) IN STREAM WATER TOPOGRAPHIC LEGEND -4300- CONTOUR INTERVAL 100 FEET (31m) CREEKS LOCAL GRID COORDINATES TRAVERSE LINES SAMPLE LOCATION GEOCHEMICAL LEGEND ° LESS THAN 5 PPb • 5-25 PPb ® -26 - 130 ppb # MORE THAN 1 3 0 ppb • 4000 F E E T I -1 /-\ r\r\ ' "I" J 1000 M GEOCHEMISTRY OF FISH AND PORTNOY LAKES ON FIGS 65-6 ; 6 9 - 7 0 FIGURE 64B: PORTNOY CAMP MOLYBDENUM (ppm) IN STREAM SEDIMENTS, "80 MESH FRACTION TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND -4300- CONTOUR INTERVAL 100 FEET (31m) • CREEKS -= LOCAL GRID COORDINATES — — TRAVERSE LINES «•• SAMPLE LOCATION less 1han 12 ppm 12 - 36 ppm 36 - HO ppm more than 11.0 ppm 4000 FEET 280 0% FISH LAKE O 3 -co) POE . a FIGURE 64C: PORTNOY CAMP |v10LYBDENUM(ppm) IN TOP OF THE 'B' SOIL HORIZON, "80 MESH FRACTDN TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND -4300- CONTOUR INTERVAL 100 FEET (31m) CREEKS LOCAL GRID COORDINATES TRAVERSE LINES ••• SAMPLE LOCATION . less than 13 ppm • I3"4 I ppm • 41 - 130 ppm O more than 130 ppm 1000 FEET GEOCHEMISTRY OF- FISH AND PORTNOY 1000 M LAKES ON T FIGS 6 5 - 6 : 6 9 - 7 0 281 zones. Sequential extraction data are unavailable to a i d interpretation of the genesis of bank s o i l anomalies. However metal accumulation along a break of slope environment, i n association with metal-rich stream water, and organic matter and amorphous Fe oxide scavenging i n streams suggests a hydromorphic o r i g i n for many of the Cu and Ho bank s o i l anomalies. i i . Trace metal d i s t r i b u t i o n i n lake sediment S u r f i c i a l sediment of Fish Lake can be divided on the basis of Cu, Zn, Fe, Hn and Mo concentrations (Fig 65) in t o 2 groups according to sample position within the lake. Zn and Fe are r e l a t i v e l y enriched i n the western half of the lake (Fig 65 and Table XXXIV). In view of the fa c t lake sediment Zn and Fe concentrations are s i m i l a r to inflowing stream sediment contents, Fe and Zn enrichment apparently r e f l e c t s sedimentation by the major inflowing stream. Cu, Mo and Hn leve l s are r e l a t i v e l y low i n t h i s part of the lake, and sand qrains only comprise a minor proportion of the sediment on a dry weight basis. Nevertheless, sand deposition i s s i g n i f i c a n t because i t d i l u t e s organic matter content of lake sediment (Fig 65). In the east, Cu, Ho and Mn l e v e l s are enhanced up to 84 ppm, 50 ppm and 275 ppm, respectively* whereas Zn and Fe l e v e l s are r e l a t i v e l y low i n t h i s narrow (20 m wide) and organic-rich half of the lake. Zones of Cu and Mo accumulation, i n a portion of Fish Lake surrounded by bogqy ground, l i e along the base of the same slope as the Cu and Mo anomalies along Portnoy Creek. Plots of trace metal l e v e l s across the lake versus lake depth indicate Cu, Mo and Fe-rich sediment i s found near the F I G U R E A C O P P E R L A K E / S T R E A M S E D I M E N T S TOPOGRAPHIC L E G E N D • U'<tL[ LOOtIS — • c - c e « i GEOCHEMICAL . LEGEND"" • • LESS THAN 3S/S0 PPM • 38-5Q/S0-190 PPM • 51-75/191-430 PPM . _ • MORE THAN 75/130 PPM GEOCHEMICAL LEGEND • LESS THAW 0,79/2.12 • 0.79-1.0/2.1-3.92 • 1.1-1.3/1.0-7,2? © MORE THAN 1.3/7.23! FIGURE B FISH LAKE ZINC L A K E / S T R E A M SEDt/.ENTS T O P O G R A P H I C L E G E N D • SAtaPlC LOCATION O COfilftS STATION —»» C h C t H l GEOCHEMICAL LEGEND • LESS THAN 30/39 PPM • 30-39/39-66 PPM • 10-50/67-115 PPM O M3RE THAN 50/115 PPM FIGURE E MANGANESE LAKE/STREAM SEOil.'.EUTS TOPOGRAPHIC LEGEND - «AN' i l LOCATION 9 C l h i l t l NATION — • CNCUI G E O C H E M I C A L L E G E N D • LESS THAN 150/365 PPM • 150-190/3C5-10CO PPM . • 191-250/10PO-2SOO PPM • MORE THAN 250/2S0O PPM FIGURE C FISH MOLYBDENUM LAKE/STREAM SEDIMENTS TOPOGRAPHIC LEGEND • l A U P L t LOCATION GEOCHEMICAL LEGEND • L E S S THAN 7.6/12 PPM • 7.6-17/12-36 PPM ' • 18-38/3/-110 PPM MORE THAN 36/110 PPM FIGURE F FISH L A K E -ORMIIIC MATUR LAKE SEDIMENT "~ TOPOGRAPHIC LEGEND • IAMr\.| LOCATION • CO*iti« fTATKM * CftTCM GEOCHEMICAL LEGEND • L E S S THAN 31.7/—I • 3W.746.0/- - -I • 16.0-60.9/- - -I • MORE THAN 60.9/-I F I G U R E 6 5 : T R A C E E L E M E N T C O N T E N T ( P P M ) I N L A K E / S T R E A M J 2 0 0 ' M E T E R ^ S E D I M E N T A N D O R G A N I C M A T T E R I N L A K E S E D I M E N T F R O M F I S H " L A K E / - 8 0 M E S H F R A C T I O N / N I T R I C / P E R C H L O R I C A C I D A T T A C K OO F I G U R E A F I S H ' COPPER (PPB)' L A K E / S T R E A M W A T E R T O P O G R A P H I C L E G E N D . SAMPLE LOCATION » CORillO S1A1ICN — * CREEK) G E O C H E M I C A L L E G E N D • LESS THAN 2/4 PPB • 2-4/4-9 PPB o 5-6/10-26 PPB @ MORE THAN 6/26 PPB L A K E / S T R E A M W A T E R T O P O G R A P H I C L E G E N D . S A i / r i t IOCATWN • eopino STATIC! CflCCXS .. G E O C H E M I C A L L E G E N D • ^LESS THAN 340/175 PPB • 340-470/175-1090 PPB . • C71-132Q/1091-6890 PPB S MORE TtftM 132(VGS90 PPB F I G U R E B F I S H ZIIIC (PPB) L A K E / S T R E A M W A T E R T O P O G R A P H I C L E G E N D • «AM*.e LOCATION conma STATION » CflEEKS G E O C H E M I C A L L E G E N D • LESS THAN 7/4 PPB • 7-9/4-7 PPB • 10-12/8-19 PPB 9 MORE T>IA.N 12/29 PPB F I G U R E E F I S H LAKE~ riAllfiAIIESE (PPB) L A K E / S T R E A M W A T E R T O P O G R A P H I C L E G E N D • J & U ^ C LOCATION » CSRl.'IQ STATION — * CHECKS G E O C H E M I C A L L E G E N D • LESS T\m 7/8 PPB • 7-23/8-46 PPB • 24-69/47-250 PPB • iS?Ejn«N 69/250 PPB_ F I G U R E C F I S H L A K E f'OLYEDEIIUM (PPB) L A K E / S T R E A M W A T E R T O P O G R A P H I C L E G E N D S A M P L l LOCATION • COR.SO STATION — * tnceat G E O C H E M I C A L L E G E N O ' LESS THAN 50/26 PPB • 50-lOV2cVE70 PPB • 101-150/671-17100 PPB -O MORE THAN 150/17100 PPB_ 0 FEET I. i T l l l V lY l lNI I I I X I j 20 0 METERS* F I G U R E 66: T R A C E E L E M E N T C O N T E N T ( P P B ) I N L A K E / S T R E A M W A T E R F R O M F I S H L A K E 284 northern shore (Figs 67 and 68) whereas Zn and Mn are equally abundant along both shores. S i m i l a r l y , Cu, Zn, Fe and, i n part, Mn contents of lake water are enriched nearshore compared to the middle of the lake. Enhanced l e v e l s of Fe and Mn, however, are also found near the lake centre. A p a r t i c u l a r l y s t r i k i n g feature of the Cu, Zn, Fe, Mn and Mo data i s an antipathetic r e l a t i o n s h i p between metal l e v e l s i n sediment with those in ;water taken at the same sample l o c a t i o n . Although i n absolute terms, metal contents of sediment exceed those of overlying water by factors of 10* to 10*, i n r e l a t i v e terms within the lake, metal-rich sediment (Fig 65) i s commonly associated with'metal-poor water (Fig 66) and vice versa. For example. Mo-rich water overlies Mo-poor sediment along Line N» (Fig 67). S i m i l a r l y , Zn, Fe and Mn-rich sediment i s o v e r l a i n by water containing low or only s l i g h t l y enhanced levels of the same elements compared to metal contents of water elsewhere i n the lake. Along Line SB (Fig 68) Mo-rich sediment i s associated with Mo-poor water. S i m i l a r l y , Zn, Fe and Mn contents of water are r e l a t i v e l y enhanced whereas sediment samples are r e l a t i v e l y impoverished i n these elements compared to lake averages (Table XXX and XXXIV) . Cu, though following the antipathetic r e l a t i o n s h i p , i s not consistently high along either l i n e . Correlation of trace element contents and lake physical parameters, assuming data follow normal or lognormal d i s t r i b u t i o n s , was conducted using data from 18 Fish Lake samples. S l i g h t l y better c o r r e l a t i o n i s observed assuming a lognormal d i s t r i b u t i o n (Table XXXVI). The relationship between organic matter and trace metal l e v e l s i s strong whereas 600 F E E T 183 H D I S T A N C E F R O M E A S T S H O R E D I S T A N C E F R O M E A S T S H O R E L E G E N D L E G E II D Cu in L A K E H A T E R • L E S S T H A U 2 P P B » 2 TO 3 P P B a 1 TO 6 P P B SI MORE T H A U 6 P P B Cu I N L A K E S E D I M E N T Z N I N L A K E WATER • L E S S T H A N 38 P P M t L E S S T H A N 7 P P B • 38 TO 50 P P M • 7 TO 9 P P B • 51 T O 75 P P M • 10 TO 12 P P B Q M O R E T H A N 75 P P M Q MORE T H A N 12 P P B ZII I N L A K E S E D I M E N T • L E S S T H A N 30 P P M • 30 TO 39 P P M • 10 TO 50 P P M © MORE T H A N 50 P P M 600 F E E T 183 M 300 92 600 F E E T 183 M DISTANCE FROM EAST SHORE DISTANCE FROM EAST SHORE D I S T A N C E F R O M E A S T S H O R E L E G E N D Mo I N L A K E H A T E R • L E S S T H A N 1 P P B • 1 TO 2 P P D B 3 TO 1 P P B M MORE T H A N 4 P P B •0.0 •1.2 « at m •2.1 & •3.6 • •1.8 & •6.0 Ho I N L A K E S E D I M E N T • L E S S T H A N 7.6 P P M • 7.6 TO 17 P P M • 18 TO 38 P P M • M O R E T H A N 38 P P M L E G E N D F E I N L A K E WATER F E I N L A K E S E D I M E N T • L E S S T H A N 310 P P B • L E S S T H A N 0,7951 » 310 TO 670 P P B » 0.79 TO 1.0X Q 0.671 TO 1.32 P P M s 1.1 TO 1.3X El MORE T H A N 1.32 P P M © M O R E T H A N 1.35, L E G E N D Hn I N L A K E WATER • L E S S T H A N 7 P P B • 7 TO 23 P P B a 21 TO 69 T P B IS M O R E T H A N 69 P P B HN I N L A K E S E D I M E N T • L E S S T H A N 150 P P M • 150 TO 190 P P M • 191 T O 250 P P M O M O R E T H A N 250 P P M F I G U R E 6 7 : T R A C E E L E M E N T C O N T E N T I N W A T E R ( P P B ) A L O N G L L N E [ L A K E S E D I M E N T IW, F I S H L A K E ( P P M ) A N D L A K E 0 0 cn 0 « u i if 8 JEW" O. U i o 16 2 0 M 1 M ' U»-vl TTT i i I M M ! H I 3 0 0 9 2 6 0 0 FEET 1 8 3 H 3 0 0 9 2 6 0 0 F E E T 1 8 3 H 3 0 0 9 2 • 0 . 0 • 1 . 2 • 2 . 1 • 3 . 6 • 1 . 8 • 6 . 0 6 0 0 FEET 1 8 3 M D I S T A N C E F R O M E A S T S H O R E L E G E N D D I S T A N C E F R O M E A S T S H O R E L E G E N D Cu I N L A K E WATER • L E S S T H A N 2 P P B » 2 TO 3 P P B B 1 TO 6 P P B IB M O R E T H A N 6 P P B . Cu I N L A K E S E D I M E N T Z N I N L A K E WATER • L E S S T H A N 3 8 P P M « L E S S T H A N 7 P P B • 3 8 TO 5 0 P P M • 7 TO 9 P P B • 5 1 T O 7 5 P P M • • 1 0 TO 1 2 P P B © M O R E T H A N 7 5 P P M H MORE T H A N 1 2 P P B ZN I N L A K E S E D I M E N T t L E S S T H A N 3 0 P P M • 3 0 TO 3 9 P P M t 1 0 TO 5 0 P P M • MORE T H A N 5 0 P P M D I S T A N C E F R O M E A S T S H O R E L E G E N D Mo I N L A K E WATER MO I N L A K E S E D I M E N T • L E S S T H A N 1 PPB a 1 TO 2 PPB B 3 T O 1 PPB El M O R E T H A N 1 PPB • L E S S T H A N 7 . 6 P P M • 7 . 6 TO 1 7 P P M • 1 8 T O 3 8 P P M © M O R E T H A N 3 8 P P M DISTANCE FROM EAST SHORE L E G E N D DISTANCE FROM EAST SHORE ' L E G E N D F E I N L A K E WATER F E I N L A K E S E D I M E N T MN I N L A K E WATER MN I N L A K E S E D I M E N T . L E S S T H A N 3 1 0 P P B • L E S S T H A N 0 .79X • L E S S T H A N 7 P P B • L E S S T H A N 1 5 0 P P M • 3 1 0 T O 6 7 0 P P B • 0 . 7 9 TO 1 . 0 Z • 7 TO 2 3 P P B . • 1 5 0 TO 1 9 0 P P M • 0 . 6 7 1 TO 1 . 3 2 P P M 9 1.1 T O 1 . 3 Z B 2 1 TO 6 9 P P B • 1 9 1 TO 2 5 0 P P M S H O R E T H A N 1 . 3 2 P P M ® M O R E T H A N 1 . 3 Z Q M O R E T H A N 6 9 P P B © MORE T H A N 2 5 0 P P M F I G U R E 68: T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D L A K E W A T E R ( P P B ) A L O N G L I N E S E / F I S H L A K E 287 corresponding associations with Fe are not evident. Relations between Fe and Bn are negative (r=-0.56), and Mn follows a trend towards increased concentration with lake depth (r=0.53). Multiple regression analysis y i e l d s equations which explain 40 to 601 of the Co, Zn and Mo v a r i a b i l i t y , and a very minor proportion of the Mn v a r i a b i l i t y (Table XXXVII). Fe content i s not a s i g n i f i c a n t independent variable, i n notable contrast to the importance of organic matter concentrations. In addition, Mn v a r i a b i l i t y cannot be attributed to any of the usual parameters. Sequential extraction data indicate almost a l l of the Cu, Mo, and Mn concentrations of lake sediment are released on oxidation of organic matter by hypochlorite (Fig 17)., Therefore, f a i l u r e of regression analysis to explain a larger f r a c t i o n of the trace metal v a r i a b i l i t y probably i n d i c a t e s heterogeneity i n the constitution of organic matter. Fe and Zn contents are probably s i m i l a r l y affected. However, v a r i a b i l i t y i n Fe and Zn l e v e l s may also be introduced by fluctuations i n concentrations of amorphous Fe oxides and s i l i c a t e residues across Fish Lake. Three lake cores were coll e c t e d near the Fish Lake Cu - Mo anomaly (Fig 59). Trace metal contents are approximately constant with depth into sediment. However increasing or diminishing sequences of values with depth are encountered l o c a l l y , nature of these sequences varies with p r o f i l e under consideration. For example, i n core 1559 (Table XXXVIII), Cu and Mo values decrease to t h e i r lowest l e v e l s i n Fish Lake, whereas Fe and Hn contents increase to the i r highest l e v e l s . By Table XXXvI Correlation c o e f f i c i e n t s (r>±0.40) for variables i n f i s h and Ecrtncy lakes A. f i s h lake n=18 Normal Icgnormal d i s t r i b u t i o n d i s t r i b u t i o n CM-Cu 0.67 0.75 CM-Zn 0.66 0.68 CH-Fe 0.72 0.69 GM-Hc 0.56 0.66 Bn-B 0.53 0.53 Fe-H 0.65 Cu-Zn 0.72 0.77 Cu-Bo 0.96 0.88 Zn-Fe 0.62 0.55 Zn-Hc -0.76 -0.86 Fe-Mn -0.56 B. Portnoy lake n=12 Normal Icgnormal d i s t r i b u t i o n d i s t r i b u t i o n Cu-DFS -0.10 -0.40 CM-Zn -0.49 -0.56 OM-Mn 0.85 0.80 Cu-Zn 0.50 0.55 Cu-Fe 0.52 0.56 Zn-Fe 0.48 0.46 Zn-Mc -0.44 Fe-Mn 0.53 fln-Ho 0.74 0.56 OM - organic matter DFS - distance from shore D - lake depth Table XXXVII Multiple regression analysis of the trace metal content i n s u r f i c i a l sediment of Fish Lake, assuming t o t a l i r o n , organic matter and lake depth independent va r i a b l e s l o g [ C u ] - 0.133[OH] 4 1.103 B* = 56.335 l o g [ Z n ] = -0.0101[OM] • 1.828 B* = 45.98 log[Hn] = 0.0263[D] • 2.079 B2 = 28.68 log[Ho] = 0.0288[OM] - 0. 155 B2 = 43.88 n - 1 8 Regression equations calculated by backwards stepwise regression using the UBC *TRIP computer program. Distance from shore, water temperature, and water pH were assumed i n i t i a l l y to be independent variables, but were found to be i n s i g n i f i c a n t i n explaining trace element v a r i a b i l i t y OM - Organic matter content determined by the Leco method D - lake depth 290 contrast, Fe and Hn contents of core 1557 diminish s u b s t a n t i a l l y whereas Cu, Zn and flo concentrations fluctuate apparently randomly near the s u r f i c i a l sediment Cu - Ho anomaly. Further into the lake (core 1556); Fe l e v e l s once again increase, from 1.4% to 2.7%, whereas Cu, Zn, Ho and Hn le v e l s exhibit a seemingly random pattern. b. Portnoy Lake i . Geochemical dispersion towards Portnoy Lake Trace metal content of s o i l s near Portnoy Lake i s affected by nature of the underlying geology and by presence of boggy areas (Line 1, Fig 61). S o i l s are predominently r e s i d u a l , and are characterized by enhanced Cu (up to 111 ppm). Ho (30 ppm) and r e l a t i v e l y high Zn (140 ppm) l e v e l s (Table XXXV) over the massive andesite flow unit west of Portnoy Lake. To the east, Cu and Zn values increase to maximum values of 163 and 240 ppm, respectively, i n association with a pyroclastic unit. Although a s i m i l a r enhancement i s seen in Fe and Hn concentrations, Ho levels diminish to below 10 ppm. Host of the Cu, Zn, Fe and Mn content of s o i l samples i s bound i n s i l i c a t e residues whereas by contrast. Mo i s held primarily by amorphous and c r y s t a l l i n e Fe oxide phases. A large f r a c t i o n of the Cu content of p r o f i l e 1756 to 1760 (Table XXXIX) has accumulated i n association with amorphous Fe oxide phases near the base of slope next to Portnoy Lake (Fig 59) . No major stream flows into Portnoy Lake. A small channel i n the south, draining part of the Portnoy Lake bog, contains only average values of Cu and Mo. S i m i l a r l y , trace metal 291 Table XXXVIII Trace element content (ppm) i n lake sediment cores from Fish and Portnoy lakes, -80 mesh f r a c t i o n , n i t r i c / p e r c h l o r i c acid attack F I S H L A K E CCBE MIKBEK 1556 i Depth CU Zn Fe Hn no Sand pp» FF» * FF» Ft» X o a 29 .5 37 .9 1.44 16.9 6 .0 .3 » 9 3 3 . 3 50.6 1.58 116. 7 .5 .2 9 16 28 .8 2 5 . 5 2 .26 59 .4 7 . 5 .1 16 23 0 6 . 3 46. 1 2 .68 B6.Z 5 . C .2 CCKF. KUHBER 1557 Depth Cu Zn re BE TO Sand C I PF» p f B * PJ>». PF» % 0 9 : 40 .7 27 .2 1.26 b9 . 0 15.0 3 . 3 9 13 45 .8 24 .5 1.05 75 . 2 2 0 . 0 2 .1 13 17 41 .2 35 .9 1.47 S 2 . 0 1O.0 4 .4 i COSH dUUSES 155S Depth Cu Zn Fe HO Mo Sand ca '• ppB PF» S ppa FF» % 0 9 , 25 .2 29.2 1.70 1C4. 7 . 5 28.1 9 16 , 16 .2 25 .1 1.70 110. 2 . 5 37.4 • 16 23 22 .1 34 .6 1o69 112. 2 .0 . 43 .7 23 2 7 5 .9 22.1 1.91 118. 0 .1 66.9 PORTNOY L A K E CCBE DUMBER 1746 Depth Cu Zn Fe (In Bo Sand ca ppn ppm > p p B ppa % 0 4 18.0 39 .9 .85 124. 7 .5 . 2 4 8 2 2 . 5 7b . 1 .64 136. 20 .0 .2 8 13 27 .9 57.1 1.13 98.1 25.0 .3 13 19 32 .9 50 .9 1.05 70 . 1 25 .0 .2 CCf E NUMBER 1747 Depth Cu Zn Fe Mn (to Sand ca PPO p t B t ppm ppa % 0 3 15.7 131. 1. 1 8 170. 10.0 .1 3 6 20 .9 77 . 2 .72 71.6 20 .0 .2 6 13 31 . 0 54. 9 1.19 50. 7 20 .0 . 1 13 22 38 .7 55 .2 . 87 42 .4 35.0 .2 COBE NUMBES 1 7 « 9 Depth Cu Zn Fe Hn Mo Sand CB ppffl ppB % ppa ppa S 0 5 5 13 13 20 20 29 29 34 17.0 35.6 34.6 89.7 20.5 59.9 68.7 71.5 179. 187. .90 1.24 1.31 1.69 3.03 79 .4 58.4 68 .2 135. 225. 13.0 23.0 20.0 40.0 280. .1 .2 .2 .3 . 2 Table XXXIX Sequential extraction of copper, z i n c , i r o n , manganese and molybdenum (percent extraction) from selected s o i l p r o f i l e s . Fish and Portnoy lake area o o PROPORTION OF COPPER E X T R A C T E D BY S E O U E N T I A L REAGENT NUMBER PROPORTION OF Z I N C E X T R A C T E D BY S E O U E N T I A L REAGENT DUMBER PROPORTION OF IRON EXTRACTED DY. SEQUENTIAL REAGENT NUMBER P R O P O R T I O N OF MANGANESE E X T R A C T E D BY S E O U E N T I A L REAGENT NUMBER P R O P O R T I O N OF MOLYBDENUM j E X T R A C T E D B Y S E Q U E N T I A L ! REAGENT NUMBER I a o IC c a 1 2 3 1 5 6 7 Cot o i_> 1 2 3 1 5 6 7 O O o t_» . J 1 I } iii, 5. ft L o d k 1) 5 6 7 o l_> O I. J 1 2 3 1 5 6 7 o <_> 0 *_> < 157C LH 0 2 82 02 01 OS 00 0) 03 103 ol 06 do U S 9} o \ II 61 <fi 56 oil 194d 6 l to 66 64 14 02 15/1 OM 2 4 00 01 01 13 00 27 57 30 57 00 00 00 07 00 00 93 140 55 00 00 00 10 43 00 39 2510 100 0 0 0 0 01 C6 07 04 02 134 100 00 00 00 27 72 00 00 20 45 20 in 1572 BM 510 03 01 01 15 00 36 45 53 51 00 00 00 06 00 00 94 51 40 00 00 00 16 36 00 48 2130 119 0 0 0 0 00 C2 05 04 00 111 124 00 00 00 24 74 00 01 25 50 29 _J 1573 c 1014 00 CI 00 14 01 40 43 60 56 0 0 00 0 0 06 0 0 oo 94 42 41 00 0 0 00 13 34 00 52 2190 116 CO 00 CI 02 05 04 07 120 121 00 00 00 10 02 0 0 0 0 30 46 20 o tn 1530 LH 0 2 72 01 01 13 03 06 04 07 255 61 11 07 00 00 00 13 56 93 13 00 00 40 21 3 22 0320 76 02 01 07 04 01 01 03 322 06 77 0 0 00 22 00 00 00 04 602 C9 UJ 15H1 BP 2 8 0 0 01 01 22 06 26 45 50 57 UO 00 0 0 01 00 00 90 l eo 49 00 00 00 20 31 CO 49 2100 120 CO 00 01 04 06 04 86 117 116 05 0 0 00 10 69 00 07 20 60 34 js 1582 llC 012 00 01 01 21 06 21 50 37 69 00 uo 00 09 00 00 90 210 50 00 00 00 22 33 00 44 2240 122 00 00 C3 06 07 05 79 130 112 32 0 0 00 15 40 00 05 25 01 30 X 1513 LH 0 2 54 c 03 13 00 00 26 . 04 161 ll) 07 04 20 00 00 50 23 106 03 00 00 36 27 06 34 073C 140 37 03 ce 10 02 02 39 113 127 05 00 00 12 03 CO 00 02 203 30 1594 A5 2 3 uo 09 07 37 00 00 47 03 90 00 04 03 26 00 uo 67 10 104 00 00 00 35 33 00 31 0020 159 00 on 05 14 04 03 72 52 1 75 00 'oo 00 92 07 00 00 01 162 32 u . 15 = 5 af 3 0 0 0 C4 03 32 00 17 44 09 64 00 00 00 06 00 00 95 29 62 00 00 00 32 31 00 37 1730 130 00 0 0 C2 03 06 04 05 76 140 00 00 no 51 49 00 00 06 49 31 lb'Jo OM 015 00 03 02 29 00 27 39 13 62 00 00 00 06 00 00 94 25 46 oo oo no 19 32 00 49 1500 131 01 00 CO 02 06 05 06 9 7 135 00 00 00 25 75 00 00 05 . UO 33 1610 L H 0 2 60 C2 03 10 00 04 12 10 103 16 04 04 36 00 00 40 25 104 06 00 00 29 .27 02 35 0600 146 47 03 13 12 03 02 20 261 97 00 00 00 07 04 01 no 10 124 70 1611 OM 210 00 04 09 54 00 13 20 10 62 00 00 01 43 UO 00 56 22 50 00 00 00 30 25 00 37 1330 127 00 00 05 27 03 05 59 116 110 46 00 00 52 02 00 00 07 95 32 l o l 2 1111015 00 C2 05 62 00 16 14 12 05 CO 00 00 40 00 00 59 24 51 00 00 00 32 22 CO 45 13C0 166 01 00 05 31 04 04 55 172 120 09 CO 00 09 02 00 00 OS 04 32 1613 C 1522 11 04 06 51 00 12 16 00 01 00 00 00 3 7 00 00 63 19 40 00 00 00 27 22 00 50 1100 140 00 00 C2 10 03 05 72 109 133 56 00 00 43 01 00 00 06 155 34 1620 I H 0 1 00 07 05 40 00 26 22 05 75 ' 00 00 00 35 00 00 65 53 43 00 00 00 27 20 00 45 2150 122 05 01 14 31 04 04 41 232 104 01 01 01 01 95 01 01 00 30 1629 Of 1 7 00 05 03 32 00 23 36 09 50 00 00 00 06 00 00 94 90 34 00 00 00 22 20 00 50 2510 125 00 00 C3 04 05 04 0 J 1-.0 112 tu 00 00 OJ 16 00 00 01 30 16.10 DM 715 00 05 03 41 00 21 30 11 51 00 00 00 16 00 00 04 44 35 00 00 00 21 25 00 54 2360 117 00 00 02 06 Ci Oo 03 162 1 CO 39 00 00 00 61 00 00 02 42 1631 C 1524 10 C3 02 40 00 11 26 11 67 00 01 00 20 00 00 79 30 53 00 00 00 24 23 00 53 2240 121 01 CC 05 14 05 05 64 206 47 01 01 01 01 95 01 01 00 35 1645 9H 012 30 01 03 38 00 02 27 60 09 00 00 00 03 00 00 97 40 99 00 00 00 26 10 00 63 2030 123 01 oc 02 42 03 03 40 278 96 20 00 00 62 01 09 00 15 70 25 16-.6 0 TI i 10 15 CI 05 53 00 02 24 43 00 00 00 00 02 00 00 90 47 90 00 00 00 36 11 00 52 2J10 116 00 03 C? 46 06 03 42 416 01 36 00 00 57 05 05 00 25 124 24 1570 IH 0 2 82 02 01 00 00 03 03 7 183 01 06 04 04 00 00 04 60 116 43 01 02 03 32 C4 10 0032 160 92 C4 C3 01 ci CO 00 1940 61 76 00 00 00 23 00 00 04 14 C2 1571 BM 2 5 OC 01 01 13 00 27 57 30 57 00 00 00 07 00 00 93 140 55 00 00 00 13 43 00 39 2510 103 00 00 c: 06 07 04 02 134 ICO 00 00 00 27 72 00 00 20 45 28 1572 B1 510 03 01 01 15 00 36 45 53 51 00 00 00 06 00 00 94 51 48 00 00 00 16 36 00 48 2130 119 CO OC CC 02 « 04 08 i l l 124 00 CO 00 24 74 00 01 25 50 29 0 1573 C 1014 CO CI 00 14 01 40 43 60 36 00 00 00 06 CO 00 94 42 41 00 00 CO 13 34 00 52 2190 116 CO 00 01 02 05 04 07 120 121 00 CO 00 18 02 CO 00 30 46. 28 LU 1790 AH 0 1 00 00 06 27 00 25 34 12 74 CI 00 01 30 00 00 60 31 66 00 00 00 36 29 00 33 2040 119 04 01 11 24 04 05 49 173 113 26 00 00 54 20 00 00 14 92 34 1791 BP I 9 00 00 01 13 00 21 65 53 62 00 00 00 06 00 00 93 100 43 00 00 00 10 44 00 37 3440 117 00 00 11 06 09 04 70 195 112 14 00 00 18 67 00 00 30 73 29 .3 1792 BM 915 00 00 01 11 00 31 50 107 60 CO 00 00 04 00 00 96 50 50 00 00 00 13 35 00 52 2780 112 CO OC C2 C3 C7 C6 82 162 111 11 00 00 08 01 00 00 30 00 31 > O 1793 C 1520 uo 00 01 11 00 31 57 111 62 00 00 00 04 00 00 96 45 56 00 00 00 15 31 00 53 2 700 115 00 00 C5 C3 05 06 01 173 115 10 00 00 15 75 00 00 30 67 22 Z i — 1 756. AH 0 1 65 03 02 .09 CO CO 13 08 120 28 03 05 10 00 00 54 16 109 12 01 00 18 2 3 01 46 5500 108 37 03 CI 05 C2 02 45 69 125 50 00 00 40 10 00 00 01 27 O 1 757 OF 1 7 00 02 02 29 17 26 23 19 57 00 00 00 12 00 00 80 32 55 00 00 00 18 30 CO 44 2140 122 CO 00 02 0 3 06 04 04 93 131 00 00 00 19 01 00 00 0 66 26 Q_ ,1750 B.M 716 04 C2 02 15 06 45 26 31 54 01 00 00 06 00 00 93 • 25 40 00 00 00 15 31 00 53 2150 117 CC OC CI C2 06 07 04 112 112 00 00 00 20 00 00 00 10 75 4C 1 759 C 1634 03 01 01 46 07 20 13 34 61 01 00 00 43 00 00 55 23 30 00 00 00 37 20 00 43 1990 115 01 00 07 12 C4 06 71 125 115 CO 00 00 04 16 00 00 0 96 4C 17oC C 3442 OC 01 02 54 10 20 13 40 59 00 00 00 54 00 00 46 27 28 00 00 00 35 19 00 45 2130 114 02 00 16 10 04 05 56 120 114 17 00 00 74 09 00 00 0 04 27 ui 1779 Ah 0 1 24 00 00 00 00 21 47 72 95 01 00 00 10 00 00 00 140 74 01 00 00 20 46 01 32 4600 110 0? 00 04 14 07 05 61 473 50 03 00 00 15 02 00 00 8 122 ce Z .1780 BM 1 8 04 00 00 11 00 15 69 155 91 00 00 00 01 00 00 90 210 94 00 00 00 08 55 00 37 5600 115 01 01 C5 10 12 02 60 590 00 34 00 uo U9 53 00 00 0 71 07 Zj 17dl OH 010 02 CO 00 10 00 13 7* 163 97 CO 00 00 <H 00 00 90 240 89 00 00 00 06 52 00 42 ISO 00 116 01 00 16 16 10 02 55 792 07 00 00 00 12 07 00 00 a 49 06 O r g a n i c a l l y bound m e t a l 2. Amorphous Mn o x i d e s 4. C r y s t a l l i n e Fe o x i d e s 6. S i l i c a t e r e s i d u e s Exchangeable m e t a l Amorphous Fe o x i d e s Hydrogen p e r o x i d e C o n c e n t r a t i o n * - ' t o t a l ' d e t e r m i n a t i o n by a s e p a r a t e n i t r i c / p e r c h l o r i c e x t r a c t i o n Comparison* - sum o f s e q u e n t i a l extrac-H o t i o n v a l u e s / ' t o t a l ' d e t e r m i n a t i o n ^ v a l u e X 1 0 0 293 content of the stream draining Portnoy lake, and the major spring* are only average for the property. However trace element l e v e l s of the Portnoy Lake bog are enriched i n Cu, Zn and Ho (up to 130 ppm, 300 ppi and 18 ppm, respectively) compared to nearby mineral s o i l s . The Zn d i s t r i b u t i o n i s notable because of the 6X enhancement i n l e v e l s to the east compared to the west. i i . Trace metal d i s t r i b u t i o n i n lake sediment Portnoy Lake sediment can be divided into 2 groups on the basis of trace element d i s t r i b u t i o n s which appear to be influenced by geological parameters. Lake sediment near the py r o c l a s t i c unit i s enriched i n Zn and Fe compared to sediment downslope of the Portnoy Zone where Cu, Ho, Hn and organic matter concentrations are enhanced (Fig 69) . Zn and F e - r i c h lake sediment overlies a small portion of the lake f l o o r downslope of the Zn s o i l anomaly. S i m i l a r l y , zones of Cu and Ho enrichment are r e s t r i c t e d to a very small area of the lake f l o o r downslope of the chalcopyrite-molybdenite showing., Enhancement of Ho l e v e l s up to 80 ppm (lake average 16 ppm) complements organic matter enrichment i n t h i s part of the lake (Fig 69). Contrary to Fish Lake, Zn and Fe enhancement accompanying lower organic matter contents cannot be attributed to c l a s t i c inputs of an inflowing stream. Greatest concentrations of Cu, Zn, Ho and Fe are centred near rapid changes of slope on the lake f l o o r (Fig 71) i n close proximity to shore. Greatest contents of these elements i n overlying lake water (Fig 70) do not coincide with metal 1 CO FIGURE A PORTNOY LAKE, LAKE/STREAM SEDIMENTS COPPER TOPOGRAPHIC LE6Et!f GEOCHEMICAL LEGENC • SAMPLE LOCATION • LC33 THAN 29/60 PPM MIZ',"""" . 29 - 33 , 60- 190 PPM • 33 • 37 / no • 4J0 PPH FIGURE B PORTNOY LAKE, LAKE/STREAM SEDIMENTS ZINC TOPOGRAPHIC LEGENO GEOCHEMICAL LEGEND • S A U P L f LOCATION . LCTJ f H A N S J / 33 PPM 0 C0RIH6 STATION — CHICHI 0 33 • 63 / 3» - S6 P P M @ 63 - 60 / 66 - 113 P P M FIGURE G PORTNOY LAKE, LAKE/STREAM SEDIMENTS MOLYBDENUM TOPOGRAPHIC LEGEND GEOCHEMICAL LEGtNO • SAAIPLC LOCATION . LCSS T H A N It / 12 PPM 0 COHINO STATION — MCE«» • IS - 29 / rt • 36 PPM • 29 • 49 / 36 • 110 PPM 0 K M C THAU 37/ 430 PPM © "out THAN eo / 113 PPM $ H.VNC THAN 49/110 PPM FIGURE D PORTNOY LAKE, LAKE/STREAM SEDIMENTS IRON TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND - SAMPLC LOCATION • LL3S THAN 0-47/24% 0 COHItig SfATKHl CBCtKI • 0/47 • 0-62 / M • » % # 0 62 -0-00/ 3-9- 7-2 * FIGURE E PORTNOY LAKE, LAKE/STfiCAM SEDIMENTS MANGANESE TOPOGRAPHIC LEGEND GEOCHEMICAL LCG*".i:& • SAUPLC LOCATION E LCSS IHAM 60 / 36 3 P P U o conuio STATION ^ - CSCCHS 0 BO • 130 / 363 - 1000 PPM © BO • 213 / 1000 - 2800 PP* FIGURE F PORTNOY LAKE, LAKE SEDIMENT • OKf-ANIC M A T ! UU TOPOGRAPHIC LEGEND — GEOCHEMICAL LEGEND i S S " ' LESS THAN <fl.tV-X 9 W.o-9i.Q/- - -% . • 91.1-65,6/- - -I ® MDRF THAN f.S.fl/—1 0 ' M M C IIIAH 0 6 0 / 7 2 % © M i i . L IIIAII 213 / 2800 P PM I600 FEET j '200 METERS^ F I G U R E 6 9 : T R A C E E L E M E N T C O N T E N T ( P P M ) I N L A K E / S T R E A M S E D I M E N T A N D O R G A N I C M A T T E R I N L A K E S E D I M E N T F R O M P O R T N O Y L A K E , - 8 0 M E S H F R A C T I O N , N I T R I C / P E R C H L O R I C A C I D A T T A C K CO FIGURE A PORTNOY LAKE, LAKE/STREAM WATER COPPERJPPB) ' • TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND • tumt LOCATION • LESS THAH PP3 O CORIMO STATION • — CHECAS • 1-2/1-7 PPB • W/llV?fi ppa FIGURE B PORTNOV LAKE, LAKE/STREAM WATER ZItIC (PPB) TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND • LOCATION . LJSS T H W 9/t| pptj 0 COBINO STATION N R R ° — "««» • 9-11/1-7 PPB. • 12-13/2-19 PPB • HOPE THAN 4/2G PPB • • HOPE THAN 13/19 PPB FIGURE C PORTNOY LAKE, LAKE/STREAM WATER ' IROfl (PPE) TOPOGRAPHIC LEGEND '. " GEOCHEMICAL LEGEND • " « f LOCATION . LESS THVI 60/175 PPE O COIIINO STATION „ * 60-88/1751090 PPB • FiGURE D PORTNOY LAKE, LAKE/STREAM WATER R/illGAHESE (PPB) . TOPOGRAPHIC LEGEND GEOCHEMICAL LEGEND •,HXX2S£r '• • LESS T.KN ]3/8 PPB . * 13-15/W6PPB * lW7/W-MDrr.p • wnE IWJI BO/tWO rr-E l 600 FEET 1 '200 METERS' F I G U R E 7 0 : T R A C E E L E M E N T C O N T E N T ( P P B ) I N L A K E / S T R E A M W A T E R F R O M P O R T N O Y L A K E 2 1-6 8' 10' 1 2 0 200 FTO 0 200 FT 0 0 61 M 0 61 H DISTANCE FROM WEST DISTANCE FROM WEST SHORE 200 FT 0 61 H 0 0.0 0.6 1.2 1.3 '2.1 •3.0 SHORE Cu IN LAKE WATER « LESS THAU 1 PPB , • 1 TO 2 PPB B 3 TO k PPB H HORE THAN 1 PPB SHORE G E N D Cu IN LAKE SEDIMENT • LESS THAN 29 PPH • 29 TO 33 PPM 9 34 TO 37 PPH © MORE THAN 37 PPM 200 FTO 0 61 M 0 DISTANCE FROM WEST DISTANCE FROM WEST SHORE L E ZN IN LAKE WATER • LESS THAN 9 PPB • 9 TO 11 PPB a 12 TO 13 PPB SHORE THAN 13 PPB 200 FT 0 200 FT 61 M 0 61 H DISTANCE FROM WEST DISTANCE FROM WEST SHORE ' SHORE G E N U ZN IN LAKE SEDIMENT MO o LESS THAN 55 PPH • e 55 TO 65 PPH . « © 66 TO 80 PPM • 9 MORE THAN 80 PPM 13 L E G E N D IN LAKE WATER NOT DETECTED NOT DETECTED NOT DETECTED HOT DETECTED Mo IN LAKE SEDIMENT • LESS THAN 16 PPM • 16 TO 29 PPM e 30 TO <i9 PPM © MORE THAN 49 PPH 10 «, 0.0 !<• 0.6 « rr LU 1.2 '••'I |2.«l JS »3.0 0 200 FT 0 200 FTO 0 61 M 0 61 M 0 DISTANCE FROM WEST DISTANCE FROM WEST SHORE SHORE L E G E N D FE IN LAKE HATER FE IN LAKE SEDIMENT • LESS THAN 60 PPB • LESS THAN • 60 TO 88 PPB • •• O . W TO 0.62" • 89 TO 130 PPB . • 0.63 TO 0.80Z IS MORE THAN 130 PPB © MORE THAN 0.80Z 200 FT 0 200 FT 61 M 0 61 M DISTANCE FROM WEST DISTANCE FROM WEST SHORE SHORE L E G E N D Hn IN LAKE WATER » LESS THAN 13 PPB • 13 TO 15 PPB • 16 TO 17 PPB E3 MORE THAN 17 PPB HN I N LAKE SEDIMENT • LESS THAN 80 PPM o 80 TO 130 PPM • 131 TO 215 PPM © MORE THAN 215 PPM F I G U R E 7 1 : T R A C E E L E M E N T C O N T E N T I N L A K E S E D I M E N T ( P P M ) A N D L A K E W A T E R ( P P B ) A L O N G L I N E S S A N D N , P O R T N O Y L A K E C N ) <o O N 297 enrichment i n sediment (Fig 69). j?or example, Fe and Mn-rich water l i e s below the break i n the nearshore slope, and further into the lake than Fe-rich sediment (Fig 71) . However concentrations of Cu, Zn and Ho i n lake water show l i t t l e v a r i a t i o n across the lake. Consequently an antipathetic rela t i o n s h i p between complementary pairs of water and sediment samples, as described i n Fish Lake, i s not apparent. Histograms indicate that trace metal contents i n sediment from Portnoy Lake follow a normal d i s t r i b u t i o n . ; Interelement c o r r e l a t i o n c o e f f i c i e n t s (Table XXX¥I) are different from those of Fish Lake, as only w€ak co r r e l a t i o n i s observed between organic matter, and Cu, Mo and Fe concentrations. However association of organic matter and fin i s strong (r=0.85) whereas a negative relationship i s observed (r=-0.49) between organic matter and Zn. Although correlation of Fe and other variables i s net evident, strong covariance i s displayed by Mn and Mo (r=0.74) i • Sequential extraction data indicate a f a i r l y constant percentage of the ' t o t a l 1 Cu (80?S) , Zn (60X),"Ho (991), Hn (705.) and Fe (15%) concentrations are dissolved by hypochlorite (Fig 17), despite the f a c t organic matter and trace metal l e v e l s vary markedly across the lake. S i m i l a r l y , a r e l a t i v e l y constant but low proportion of the Cu and Mn are simultaneously s o l u b i l i z e d with amorphous Fe oxides, and t h i s sediment f r a c t i o n i s not expected to control o v e r a l l metal v a r i a b i l i t y . High l e v e l s of Zn l i b e r a t e d b y a c i d i f i e d d i s t i l l e d water and hydroxylamine hydrochloride indicate Zn i s weakly bound. However scavenging of Zn by amorphous Mn oxides i s not corroborated by enhanced Mn 298 extraction i n hydroxylamine hydrochloride. Similarly, Hn scavenging of Ho, indicated by co r r e l a t i o n analysis, i s not confirmed by enhanced Ho l e v e l s i n hydroxylamine hydrochloride extracts because nearly a l l of the Ho i s dissolved on oxidation of organic matter. Position of core samples taken from Portnoy Lake i s i l l u s t r a t e d on Fig 59. Sediment i s primarily organic-rich at depth, and sand comprises less than 1% of the sediment on a dry weight basis (Table XXXVIII). Trace metal d i s t r i b u t i o n with depth i s more complex than at Fish Lake. Ho and Cu l e v e l s commonly increase whereas Zn contents either fluctuate randomly (ID - 1746), decrease (ID - 1747) or increase markedly from 60 to 187 ppm (ID - 1749). Ho accumulation to 280 ppm and Cu enhancement to 90 ppm greatly exceeds values i n s u r f i c i a l sediment (Fig 69). Horeover, the Ho anomaly l i e s along the opposite shore of the s u r f i c i a l sediment Ho anomaly. Fluctuations i n Fe and Hn leve l s are independent of each other. In core 1746, Mn-content decreases with depth whereas the Fe content increases. Further into the lake, Hn l e v e l s diminish whereas Fe fluctuates apparently randomly. However in the Cu, Zn and Mo-rich core, both Fe and Hn increase markedly with depth. 4. Discussion Several metal-rich l i t h o l o g i c a l units, such as the andesite or the p y r o c l a s t i c s , release s i g n i f i c a n t quantities of Cu, Mo and Zn, as does the mineralized zone, on mechanical disintegration of bedrock outcrops. Trace element contents are 299 enhanced l o c a l l y i n overburden surrounding outcrop exposures and are considered •residual anomalies 1. Many of the Cu and Mo anomalies defined by Bio Tinto (Fig 60) have t h i s r e s i d u a l o r i g i n . Anomaly extent i s primarily controlled by s u r f i c i a l deposit thickness overlying metal-rich volcanic units, although the northward extention of the Cu and Mo anomaly may r e f l e c t g l a c i a l dispersion (personal comm, Bradshaw, 1976) . Superimposed on these r e l a t i v e l y large and l i t h o l o g i c a l l y related anomalies are s n a i l anomalous zones r e f l e c t i n g the Portnoy Zone occurrence and perhaps mineralized bedrock associated with the prominent Zn anomaly east of Portnoy Lake. The Portnoy Zone represents a bedrock source of Cu and Mo from which dispersion into the overburden can be traced. The mineralized zone i s indicated at surface by a prominent s o i l Mo - Cu - Zn anomaly displaced a few tens of meters downslope of the surface expression of the mineral showing. Because streams draining the Portnoy Zone do not enter either lake, metal-rich e l a s t i c s cannot be introduced mechanically into Fish or Portnoy Lake d i r e c t l y . Moreover, s o i l anomalies do not l i e close enough to either lake to consider sheetwash erosion a s i g n i f i c a n t mechanism for t r a n s f e r r i n g metal-rich c l a s t i c material from the catchment to the lake; Therefore, a high proportion of the Cu, Zn and Mo accumulating below 1200 m must migrate as dissolved constituents of groundwater solutions. Although downslope mechanical movement of Cu, Mo and Zn from sources i n bedrock i s s i g n i f i c a n t i n proximity to outcrops, dispersion i n groundwater solution appears responsible for Cu, Zn and Mo anomalies around and within Portnoy Lake, Cu and Mo 300 anomalies around'and within Fish Lake, and Cu and Mo anomalies associated with Portnoy Creek. Cu, Zn and Mo enrichment within lakes and bogs1 i s primarily a r e s u l t of organic matter scavenging. Upslope of boggy areas, but s t i l l near prominent topographic i n f l e c t i o n s , metal enhancement i s associated with both organic matter-and amorphous Fe oxide scavenging., That Cu and Mo are accumulating i n Fish and Portnoy Lakes as a consequence of hydromorphic dispersion was f i r s t recognized by Mehrtens et a l (1973). •;• Subsequent detailed studies at the Portnoy camp reveal trace elements accumulate i n s o i l s , streams and lakes downslope of known or suspected zones of mineralized bedrock* p a r t i c u l a r l y at topographic i n f l e c t i o n s . Anomalies are commonly associated with metal-rich surface (and presumably subsurface) waters. Metal deposition follows scavenging by organic matter i n water-saturated and organic-rich bog s o i l s near Fish Lake. Further upslope, the interface between poorly-drained overburden at depth and well-drained material near the surface may favour accumulation of amorphous Fe oxide phases, although-Fe content of s o i l s near both lakes comprises l e s s than 15? of a sample* the amorphous Fe oxide component i s e f f e c t i v e i n scavenging up to 50% or more of the * t o t a l ' Cu and Mo content. Fish and Portnoy Lakes are r e l a t i v e l y small ponds completely surrounded by bogs. Stream inputs do not contribute s i g n i f i c a n t amounts of coarsely textured sediment to the lake, with the exception of one stream entering Fish'Lake. In proximity to t h i s stream, Cu and Mo contents are r e l a t i v e l y low i n -80 mesh s p l i t s used for analysis, although si z e f r a c t i o n analysis would prove i n s t r u c t i v e , i n s u f f i c e n t lake sediment 301 remains for t h i s type of study. However the stream i s not known to drain any s o i l anomalies (Fig 60), and Cu and Mo-rich lake sediment i s r e s t r i c t e d to a small zone on one side of the lake. In view of the r e l a t i v e l y homogeneous appearance of F i s h Lake sediment* s i g n i f i c a n t amounts of Cu and Mo are probably not introduced mechanically by stream inflow. Streams entering Fish Lake from the north are also r e l a t i v e l y metal-poor i n -80 mesh fra c t i o n s , although data for f i n e r f r a c t i o n s are unavailable, these streams are not considered important i n the genesis of Cu and Mo anomalies because they are r e l a t i v e l y small and do not drain any s o i l anomalies. Cu, Zn and Mo enrichment i n both lakes appears to proceed by organic matter scavenging of trace elements from overlying lake water. Coincidence of Cu and Mo anomalies in Fish Lake and Mo enrichment i n Portnoy Lake, and zones of organic matter accumulation appears to confirm t h i s genesis. In addition, organic matter scavenging i s indicated by prominence of the antipathetic d i s t r i b u t i o n of anomalous concentrations of trace elements i n lake water compared to lake sediment at the same sample lo c a t i o n . Seguential extraction data also support the hypothesis that most of the Cu, Zn, Mo and Mn, and a s i g n i f i c a n t f r a c t i o n of the Fe i s scavenged by organic matter. 5. Summary -Cu and Mo anomalies i n Fish Lake l i e d i r e c t l y downslope of the Portnoy Zone; Accumulation of these elements apparently proceeds following chemical weathering of mineralized bedrock by surface and ground waters. S i m i l a r l y , Cu and Mo accumulation 302 along Portnoy Creek and around Portnoy Lake r e f l e c t deposition of metals from groundwater solutions. In addition, Zn and Fe enrichment i n Portnoy Lake also r e f l e c t s dispersion of these elements from Zn-rich (or mineralized?) bedrock in the east. Ho-rich lake sediment at depth along the east side of the lake i s more d i f f i c u l t to explain. I t s prominence may r e f l e c t Mo derived from the Portnoy Zone and transported along deep groundwater flow paths. Alte r n a t i v e l y Mo may be leached from presently unrecognized mineralized bedrock underlying the lake. 303 CHAPTER 7 FINAL DISCUSSION AND CONCLUSIONS I GENERAL DISCUSSION A. A model—genesis of lake sediment anomalies Timperley and Allan (1974) have suggested a model to explain genesis of lake sediment anomalies. Trace elements are dissolved or mechanically eroded from metal-rich bedrock or overburden i n the • watershed and migrate downslope. Eventually, dispersion i s arrested; at least temporarily, by entry i n t o a lake which acts as a trap for mechanically and hydromorphically transported metal-rich e l a s t i c s or solutes (Fig 1) . Degree to which metals accumulate to anomalous l e v e l s depends on a great number of variables. Most important of these i s s i z e of the metal-rich bedrock source and i t s distance from the lake, e f f i c i e n c y of mechanical or chemical weathering, speed of the dispersion process, and mechanisms for p r e f e r e n t i a l l y concentrating trace elements i n the lake. Each stage of the dispersion process i s associated with a variety of complex and interacting parameters. For example, rate of disintegration of mineralized bedrock i s affected by type of mineral concentration, and by extent of bedrock f r a c t u r i n g or decomposition near the bedrock - overburden i n t e r f a c e . Hetal transfer to overburden i s also c o n t r o l l e d by physical properties of the overburden and nature of the landscape surface, and proceeds by a combination of mechanical and hydromorphic processes. Mechanical dispersion i s e a s i l y followed because of 304 development of s o i l and stream sediment anomalies i n proximity to mineralized bedrock. Honever overburden anomalies may have a variety of o r i g i n s . In s o i l s complexities are introduced by pedogenesis which tends to r e d i s t r i b u t e metals. Although mineralized bedrock i s commonly r e f l e c t e d by syngenetic anomalies* weathering of c l a s t i c sulphide minerals, and metal inputs associated with groundwater tend to give many s o i l anomalies an epigenetic character. Trace element accumulation follows scavenging by organic matter i n the 'A' horizon, and by organic matter and/or amorphous Fe oxides i n the *B* horizon. Further, v a r i a b i l i t y i n s o i l types across the landscape may pose problems i n inte r p r e t a t i o n of anomalies; Nevertheless, mineralized bedrock i s commonly r e f l e c t e d by a s o i l anomaly overlying or lying downslope from the bedrock source. Trace element dispersion i n groundwater i s d i f f i c u l t to document experimentally, although i t s importance o r d i n a r i l y i s indicated by presence of metal-rich springs and seepages, an association of base metal anomalies with breaks in topographic slope, and scavenging of trace elements by organic matter and amorphous Fe oxide f r a c t i o n s of s o i l s , stream sediments and lake sediments. Though flow paths are unknown because bedrock and overburden properties are unknown, presumably greatest volumes of groundwater flow above the bedrock - overburden interface or along impermiable horizons within s u r f i c i a l deposits. If groundwater i s able to dissolve metals from mineral showings, and'if a significant"proportion of t h i s metal survives deposition via p r e c i p i t a t i o n or scavenging reactions i n s o i l s near base of slope, i n bogs, or i n other non-lake environments. 305 i t may then be a v a i l a b l e as a p o t e n t i a l l y important input to a lake,'• I n f l u e n c e o f s o i l anomalies on lakes i s usually i n d i r e c t , although introduction of metal by wave erosion of lake banks may be s i g n i f i c a n t where a mineral occurrence l i e s near the lake margin, i n which case lake anomalies can also form as a consequence of hydromorphic dispersion. More commonly, however, s o i l anomalies and underlying metal-rich parent materials or bedrock are eroded by streams, and metal-rich detritus f i r s t enters the drainage network; Accumulation-of trace elements i n streams i s c o n t r o l l e d by many variables. Most important of these are proximity of the stream to a mineral occurrence or s o i l anomaly, and s i z e and eroding c a p a b i l i t y of the stream. Neglecting g l a c i a l transport, coarsest p a r t i c l e s and f l o a t blocks commonly are trapped near t h e i r sources whereas s i l t and clay can be transported i n suspension for great distances. Consequently, though metal le v e l s may diminish to background a short distance from a mineral showing i n routinely analyzed s p l i t s (minus 80-mesh), enhanced metal l e v e l s associated with f i n e r f r a c t i o n s might be detected for much greater distances. A l l dispersion t r a i n s decay downslope of a mineral showing because of d i l u t i o n by barren material from stream banks or tributary streams. Topographic i n f l e c t i o n s , bogs and lakes along the stream course favour slowing of the dispersion process. Stream inputs provide the most obvious contribution of metal to lake sediment. If the stream i s large enough, coarse c l a s t i c sediment i s deposited near the point of entry to form a delta. Trace element content of d e l t a i c material i s commonly low because t h i s type of sediment i s composed of a high proportion of metal-poor sand. However deposition of s i l t and clay associated with d e l t a i c sedimentation may r e s u l t i n anomalous accumulation of metal further into the lake. Metal deposition may also follow contact of metal-rich stream water and lake water. Precipitates tend to be f i n e l y - d i v i d e d and s e t t l e i n a d i s t r i b u t i o n s i m i l a r to s i l t and clay minerals. Within h y d r a u i i c a l l y - a c t i v e , shallow water environments within a lake, trace element l e v e l s can be increased or decreased by the winnowing action of waves or longshore currents. Sands and gravels are l e f t as l a g deposits nearshore whereas s i l t and clay are transferred to l e s s turbulent water near the middle*of the lake. Unless a mineral showing l i e s onshore, winnowing promotes d i l u t i o n of trace elements i n both nearshore and deep water environments. Slumping associated with deltas or elsewhere around the lake, or rapid introduction of sands during flood periods are p o t e n t i a l l y important i n providing coarsely textured material to the middle of a lake. Significance of floods cannot be understated, p a r t i c u l a r l y for lakes above t r e e l i n e which are subjected to inflows of great volumes of c l a s t i c material following cloudbursts. Groundwaterprovides a s i g n i f i c a n t proportion of inflowing water to some lakes. Metal deposition accompanying groundwater entry i s not an unreasonable hypothesis, i n view of i t s previous migration through a non-aerated zone i n overburden, and i t s passage through-reduced lake sediment prior to entering an oxidized or reduced s u r f i c i a l sediment - hypolimnion 307 environment. Deposition of solutes and concomittent metal accumulation proceeds by p r e c i p i t a t i o n or scavenging reactions throughout along the lake f l o o r ; However because greatest volumes of groundwater discharge near breaks i n bottom topography* for the same reasons as seepage anomalies characterize break of slope environments i n a drainage basin, metal accumulation characterizes narrow zones along the lake f l o o r . If bottom water i s s u f f i c i e n t l y reducing to suppress immediate deposition, trace elements migrate away from zones of emergence to precipitate more uniformly on contact with oxygenated waters; Distribution of Fe and Hn i s s t r i k i n g i n t h i s regard, and i n view of the r a p i d i t y of Pe oxidation r e l a t i v e to an (page 387, Garrels and Ch r i s t , 1965), anomalous Fe l e v e l s i n sediment may mark points of groundwater entry. The Capoose Lake, and Fish and Portnoy Lake areas are examples of watersheds containing mineral occurrences from which trace element dispersion can be followed. In both examples, syngenetic s o i l anomalies mark position of the mineral showing. At greater distances frem occurrences, s o i l anomalies tend to form by hydromorphic processes, and Cu, Zn and Mo accumulate along topographic i n f l e c t i o n s or seepage zones due to scavenging by organic matter or amorphous Fe oxides. Mechanical-dispersion i s weak i n both areas, though syngenetic anomalies l i e close to t h e i r bedrock source. Stream sediment anomalies formed by mechanical erosion of bank, s o i l s are weak, except i n the Green Lake area where Pb dispersion along anomaly Creek i s prominent i n -80 mesh f r a c t i o n s . However mechanical dispersion of metal-rich f i n e r f r a c t i o n s i s an 308 important factor i n migration of Cu and Zn near Capoose Lake. Hydromorphic inputs to streams are important, p a r t i c u l a r l y along Portnoy Creek where metal-rich water, sediment and hank s o i l s are accompanied by extensive scavenging by organic matter and amorphous Fe oxides. Seepage zone anomalies also are recognized along the banks of Swannell and Capoose Creeks. Mechanical input by streams i s a prominent feature of sedimentation i n Capoose and Fish Lakes. Inputs associated with wave erosion are also readily observed. However trace metal contents of nearshore and d e l t a i c sediments are below lake averages. Consequently, i f streams provide metal-rich sediment for lake sediment anomalies, f i n e r f r a c t i o n s must play a major ro l e i n anomaly genesis. At Capoose Lake, importance of metal-r i c h f i n e s i s confirmed by enrichment factors of 30X or more -80 mesh values i n clay sized material. Significance of dissolved loads of streams i s more uncertain, although the lake water anomaly associated with the Capoose Creek delta may r e f l e c t i n f l u x of metal-rich stream water. Groundwater i n f l u x i s probably the most important source of metal entering a l l three lakes. In Portnoy Lake, streams are absent, and groundwater i s the only source of inflowing metal. In Fish Lake* position of the Cu and Mo anomaly d i r e c t l y downslope from mineralized bedrock, and i t s disposition r e l a t i v e to stream inputs also suggest a hydromorphic o r i g i n . Metal accumulation i n both lakes i s accomplished by organic matter scavenging. By comparison, Capoose Lake presents a more complex example. Although lake sediment anomalies characterize topographic i n f l e c t i o n s along the lake f l o o r , and indicate 309 positions of greatest volumes of metal-rich groundwater inflow, other fac t o r s are also important. Mechanical dispersion of Cu and Mo associated with the South Zone occurrence i s responsible f o r a prominent anomaly nearshore, and extensive metal enrichment i n the southwest quarter of the lake. In comparison, lake anomalies downslope of the North Anomaly are weak, obscured by c l a s t i c inputs of Capoose, Swannell, Chatupa and Asarco Creeks. Nevertheless, metal accumulation along the break i n the nearshore slope i s evident throughout Capoose Lake, despite e f f e c t s associated with c l a s t i c sedimentation. A f f i n i t y of amorphous Fe oxides for Cu and Bo,, amorphous Fe'and Mn oxides for Zn, and c r y s t a l l i n e Fe oxides for Ho indicates base metal anomalies are formed by scavenging of these metals from groundwater. At an early stage of t h i s study, i t was recognized that lakes could have wide ranging physical and chemical properties. Consequently lakes were subdivided into organic-rich and organic-poor classes represented by Fish and Portnoy Lakes, and Capoose Lake, respectively. This c l a s s i f i c a t i o n often corresponds to small versus large, shallow versus deep, Fe and Hn oxide-poor versus Fe and Hn oxide-rich, and eutrophic versus oligotrophic groupings. In small, organic-rich lakes, inorganic inputs are composed of only f i n e f r a c t i o n s . High rates of organic productivity d i l u t e oxide and inorganic sediment components, and physical and chemical properties of lake sediment r e f l e c t physical and chemical properties of organic matter; Scavenging-by organic matter, development of anoxic conditions by organic matter decay, and possible p r e c i p i t a t i o n 310 of trace metal sulphides control metal accumulation on the lake f l o o r (Timperley and Allan, 1974). Groundwater often comprises the only s i g n i f i c a n t input, and metal enhancement i s probably important along zones of groundwater emergence. However because lake water contains a high content of humic acids and other soluble organic complexing agents, metals may not be extracted immediately and may be dispersed more uniformly within a lake basin. • • • • • - '* — • Organic matter content of oligotrophic lakes i s r e l a t i v e l y low and development of anoxia i n the hypolimnion i s an infreguent, i f ever, event. Consequently trace metal l e v e l s are more l i k e l y to be controlled by oxide and inorganic sediment constituents. Assuming the influence of processes operating nearshore can be disregarded near more central positions i n the lake, trace metal l e v e l s i n the l a t t e r environment then r e f l e c t trace element contents associated with primary s i l t and clay-sized minerals, and trace element contents deposited from groundwater. The example of Fe oxide scavenging, p a r t i c u l a r l y i n Fe-rich lakes,-has been described f o r Capoose Lake. If amorphous Fe oxides are not a prominent sediment constituent, t h e i r r o l e as a trace element scavenging agent may then be taken by organic matter or clay minerals. D i f f i c u l t i e s i n int e r p r e t a t i o n of lake sediment geochemical data are also introduced by a variety of limnological processes. V a r i a b i l i t y i n organic matter and Fe and Mn oxide content within a lake are s i g n i f i c a n t factors (Schoettle and Friedman, 1973), p a r t i c u l a r l y i f currents are active along the lake f l o o r . Seasonal fluctuations in dissolved oxygen content also influence 311 character and scavenging a b i l i t y of amorphous Fe and Mn oxides (Coey et a l , 1974)> and s o l u b i l i t y of many elements. Seducing conditions i n organic-rich lakes increase sulphide ion a v a i l a b i l i t y (Berner, 1969), which are able to immobilize many trace elements.-*Alternatively, elements such as antimony are released to lake water under reducing conditions (personal comm, Jonasson, 1974). A reducing hypolimnion also minimizes bottom sediment disturbance, a condition which i s changed markedly by the onset of a convective overturn i n spring and autumn (Gorham, 1958).', •• The most serious deficiency of current lake sediment geochemical surveys i s the inadequate reporting of f i e l d measurements reguired tc interprete f u l l y lake sediment trace element data;„ For example, res u l t s of regional surveys are rarely reported i n terms of organic-rich versus organic-poor lakes, or other possible lake class subdivisions. S i m i l a r l y , features such as catchment area, proximity to streams and nearshore, importance of stream inflow, f l u s h rates, and differences i n lake elevation or topographic setting are not considered. A summary of some of these parameters i s given on Fig 11. E. Comparison with other lake sediment surveys Few studies are available from the l i t e r a t u r e which describe lake sediment geochemistry within i n d i v i d u a l lakes. Nevertheless, studies by Schmidt (1956), Coker and Nichol (1975) and others (Allan*and Timperley, 1S75; Nichol e t a l , 1975) indicate great v a r i a b i l i t y i n metal leve l s accompanies multiple 312 sampling of a lake. Nearshore sediments are t y p i c a l l y impoverished i n trace metals compared to more f i n e l y - d i v i d e d nasinal sediments. However metal l e v e l s near the middle of a lake are by no means uniform, and commonly only a portion of a lake f l o o r might contain anomalous concentrations.. Consequently, the main premise of t h i s thesis that sampling of the middle of the lake i s suitable for c o l l e c t i o n of material both homogeneous and representative of catchment metal l e v e l s i s probably not accurate i n many cases, but depends on choice of sample lo c a t i o n . — Influence of mineralized bedrock on lake metal l e v e l s i s also b r i e f l y discussed. Coker and Nichol indicate abnormally high concentrations of trace elements may enter a lake i n association with inflowing streams. However i n the example of Lyon Lake (Fig 72),stream sediment dispersion of Zn does not extend very far into the lake. S i m i l a r l y , metal l e v e l s i n Trousers Lake;, Quebec (Schmidt, 1956) i l l u s t r a t e the e f f e c t metal-rich stream inputs derived from t a i l i n g s of the Huntington Cu mine have on lake metal d i s t r i b u t i o n s (Fig 73). In comparison, trace element l e v e l s i n Opsalguitch Lake, Mew Brunswick (Schmidt, 1956) are greatest nearshore (Fig 74). , This has been explained by mineralized bedrock onshore and believed to underly the nearshore environment. In t h i s respect, the Opsalguitch Lake anomaly has a s i m i l a r o r i g i n to the Capoose Lake anomaly near the South Zone. Investigations of the influence of hydromorphic dispersion on lake metal l e v e l s have not been reported. Possible e f f e c t s of the i n f l u x of metal-rich groundwater i s suggested f o r several 313 F I G U R E 7 2 : D I S P E R S I O N O F Z N , C U , M N , ( Z N / M N ) x 1 0 0 I N LAKE S E D I M E N T S ( F R O M C O K E R A N D NlCHOL, 1 9 7 5 ) 314 FIG .4-4.. TROUSERS L A K E EiTi;:t~ Ccld cx^ r values > zo C o l d exhr v a l u e s • 5 - 2 0 \ ^ y | C o l d exVr v alues 10-15 Irxr. Sdmplir\^ poinr wiVK dehiils irv. habit C o l d exrr. v a l u e s * i O S a n - d y Sedin-vcrvV. 2 5 5 A _ 2 5 S e . _ 2 G 2 & 2 7 3 A _ 2 7 f l _ _2>b _ 2 8 9 & _ _ 2 9 7 B _ „ 3 0 0 A _ _ } O G A _ _5P .SB_ Z r N . S O 9 0 7 0 _ao _|io _ 2 7 0 _ ~_7Q _ _ 8 0 _ J 7 0 _zob 7 0 0 "PH: pp_ C o U exrro .cl-ior>. " £ u ! d i r K i z o r \ . c , m.1. 0 - 0 0 * %. G O O 1 0 3 0 2 5 0 I 4 (23-?jL cf.1 t 3 2 - 7 - / o 14. I O 30 I 2 0 7 fiXt (T-OQ%<"^°' 1 6 J O 16b "120 3 _ _io_ 10 3 0 _ G O _ 7 0 _\a.oo sooo 3 S _ l " 2 _ 2 0 ^ ~ 2 4 b _ ^ V 7 % ° < ; 9 « " i J I * Tie 4 0 0 8 0 0 1 2 0 0 l & O O 1 • I . 1 1 1 F c e r | F I G U R E 7 3 : Z N , P B A N D C U C O N T E N T O F L A K E S E D I M E N T S F R O M T R O U S E R S L A K E , Q U E B E C ( F R O M S C H M I D T , 1 9 5 6 ) 315 f M I T T i C t T O LEGE.NO Cold cxl"r. values > I 5 0 1 Cold extr. values I O O - 1 5 0 \ \ \ \ C o l d exlr. v a l u e s 5 0 - 1 0 0 Cold exrr. va lues < 5 0 S a r x d y SedirrvervK FIG A\ UPSALQUITCH LAKE SccHot \ A - & : Dispersion, of rr\chais_)r\_ Jake, scdim.gn.Vs o o a r r \ p l i r \ t j p o i r v r S<Xm.plir\Cj poial" wirK •dcha.ls t n . liable.. 8 0 0 1 2 0 0 . 6 O 0 t . 1 • I Fe ct. S a m p l e r\o Heckvv n-vcl'o.ls P ^ rrx Cold . . xTrcLc l * i o r v j d i h K i c o r v C , rr\l C o o l % I Pb Cu 136 U O a IO I.SO 0 5 2 0 0 & 5 0 0 5 6 , , | 2 0 3 r i 110 0 5 I O 2 0 G 2 2 0 10 I O 13 | 2 I 2 A I 5 0 0 5 2 (l3-5X°rr,an. ) : 2 l 2 B i O O 10 3 0 14 ! 2 1 3 I 2 0 5 215 ISO 10 5 9 (33-A'%°'-'3°''l 2 I 9 A BOO 10 6 0 IO 8 Zf3S> l & O A O 3 0 IO 2 2 0 & AOO 2 6 0 3 0 & 0 2 Z I A l i O IOO IO 6 2 2 1 f t 5 0 0 S O 3 5 2 0 A (22-8"/tO'"9«"i 2 2 2 4 0 0 2 0 0 2 0 36 2 2 3 6 3 5 0 I50 2 5 Go 3 0 0 2 0 IO 6 0 2 Z A & S O U 2 0 AO I 3 Z ( l3-9% O r g a r x ] 2 2 S A 5 0 0 I20 3 0 8 A 22.se> I O O O U O 7 0 2 4 0 H2 l - 2 %<"-V\5 2 2 G A z&o 150 IO A 8 2 2 G B A S O 2 0 0 2 0 72 2 2 7 b 3 0 0 A O 10 72. 2 2 8 A A O O 2 o o 15 is (e-3%.o,-9'»") 2zae> 4 0 0 2 5 0 15 9 4 0 0 5 0 0 2 0 I Z O (37-27.orqor* 2SOSS 4 0 0 A O O 2 0 9 o 2 s i e . 2 5 0 1 0 0 3 0 7 B 2 5 3 S O A O 5 2 1 i A O S o S 12. < 8 7 - A % o r q ^ 2 5 3 I Z O A O IO e 2<VI 5t>o 2 0 0 15 8 ! J 5 - « « T 2 4 9 A 5 0 1 2 0 ' 5 2 2 / t 2^1 2 5 0 z o o 15 3 G ( 1 6 - 6 7 - o r , 3 a " > F I G U R E 7 4 : Z N , P B A N D C U C O N T E N T O F L A K E S E D I M E N T S F R O M U P S A L Q U I T C H L A K E , N E W B R U N S W I C K ( F R O M S C H M I D T , 1 9 5 6 ) 316 of the Dore Lake anomalies (Schmidt, 1956). In that case (Fig 75), a program of sampling at 61 m i n t e r v a l s across a portion of the lake revealed a series of elongated anomalies running approximately p a r a l l e l to the shoreline. These were a t t r i b u t e d to fracture zone c o n t r o l , sulphide concentrations underlying the lake, and groundwater i n f l u x . However, i n the absence of information on lake f l o o r topography, metal accumulation following deposition frem groundwater can only be suspected. S i m i l a r l y , i n t e r p r e t a t i o n of a hydromorphic genesis f o r lake anomalies reported by other workers might be suggested. However without f i r s t hand information, such suggestions are highly speculative. Controls on trace element accumulation i n lakes have been suggested following regression analysis. Organic matter, and Fe and Hn oxides are suggested most cemmonly as scavenging agents (Timperley and A l l a n , 1974; Davenport et a l , 1975; Michol et a l , 1975). Although a large proportion of the trace metal v a r i a b i l i t y can be attributed to these sediment components, re s u l t s may be spurious. For the case of Zn content i n Lake A and Corsica Lake* (Nichol et a l , 1975), two d i s t i n c t groups of data points define the regression l i n e (Fig 76).. This probably r e f l e c t s the f a c t that organic matter concentrations depend on lake environment and lake depth (Fig 77). Nearshore organic matter l e v e l s range over narrow i n t e r v a l s , and define a c l u s t e r of points on an organic carbon content versus lake depth graph (Coker and Nichol, 1975). S i m i l a r l y , intermediate and deep samples define analogous c l u s t e r s . The f a c t that organic matter concentrations do not describe a continuous seguence suggests .317 OORE L A K L ° M t R R i L L ISLAND H e a v y mcl"ols P - P - r r x . C o U g y f r e v c H o n . . d i r K i z o n . e , r r J . o - o o l % 5j.rnp le no. Zrx. P b . C U . 3 9 3 0 0 1 5 2 3 0 0 1 5 1 C 5 ' 0 % o r ^ a r v ) 4 1 ?o 0 I O 3 % o r q o , T \ ) 4 2 5 0 0 10 5 ( 7 - 2 7 . o r , o r > . ) / I S 35 O 15 2 d 4 2 5 0 5 1 ( 1 - 2% o r g a n . . ) .45 3 0 0 I O - 5 6 S O 0 L -49 3 0 0 15 5 5 0 S O 0 2 0 V ( 6 ' 7 % o r g a n . ) 61 d-5 0 1 3 0 . £, (2.-l% o r 3 0 . r O 52 1 5 i 0 5 7 53 3 0 1 0 I O 1 4 -IffiliS C o U c x r r . vcJucs -> IO C o l d e*rr . vo-lues 5 ~ i O k \ \ 1 C o i d exHr .vo. loes 3 ~ 5 I I C o l d exrr . v o J u e s < 3 M o t i v e sulphide outcrops. FIG. ^ 7 PORE. LAKE. ( C H I B Q U G A M A U ) * o O l_ So.rr\plin.g poir\.t~ Scv-rrvplip.^ po'irvr Wi . fK de ta i l s in. table. I Z S O feet c o n t o u r lirve. A O O B ° o 1 2 0 0 1 6 0 0 . I • I • I 1 1 Feet F I G U R E 7 5 : Z N , P B A N D C U C O N T E N T O F L A K E S E D I M E N T S F R O M D O R E L A K E , Q U E B E C ( F R O M S C H M I D T , 1 9 5 6 ) 318 organic matter may be derived from several sources. Though data from other areas are unavailable, on the basis of nock on the Nechako plateau, organic matter, comprised of d e t r i t a i and r e l a t i v e l y undecomposed twigs, needles and leaves nearshore, and fi n e l y - d i v i d e d material* unrecognizable to the unaided eye, near the middle of t h e l a k e i s too heterogeneous to expect successful application of regression analysis. Fe and Mn oxides have also been suggested as active scavengers (Spilsbury and Fletcher, 1974; Coker and Nichol, 1975). However ro l e of t h i s sediment f r a c t i o n i s often obscure, and regression analysis helps to explain trace element v a r i a b i l i t y i n only some lakes (Fig 76). In part, t h i s may be due to fluctuations i n the degree of c r y s t a l l i n i t y of the Fe oxides. However Fe content of lake sediment may also be controlled by the guantity of sand and the Fe content of primary minerals (Spilsbury and Fletcher, 1974). In addition, organically bonded forms of Fe may be important i n small eutrophic lakes. Importance of amorphous Mn oxides in scavenging Ni and Zn has been stressed by Coker and Nichcl (1975) and Nichol et a l (1975). They f i n d that, on the basis of single element d i s t r i b u t i o n s i n lakes of the southern Shield, i t i s often d i f f i c u l t i f not impossible to distinguish a lake adjacent to a mineral occurrence from one i n barren t e r r a i n . However once Zn/Mn and Ni/Hn r a t i o s are calculated, lakes near mineralized bedrock can be"distinguished from lakes remote from sulphide showings. Timperley and Allan (1975) note that when t h i s approach i s applied elsewhere, lakes next to mineral showings L y o n L y o n Cu , ppm C o r s i c a Cu i ppm Lake A Cu , ppm * * # " «7 "MOO 1000 1 0 0 0 1 0 0 0 3 0 0 0 Zn i ppm Zn , ppm C o r s i c a ~aolo Zn no ppm —T J " Lake A .'.«• • • \-> 100 •T:\ Organic Matter-3o lron-% Manganese-ppm Organic Marfer-°6 lron-°6 Manganese-ppm F I G U R E 76: Cu A N D Z N V E R S U S O R G A N I C M A T T E R , F E A N D M N I N N O R T H W E S T O N T A R I O A R E A ( F R O M NlCHOL E T A L , 1975) 320 Shore — • — Intermediate — Center 20 ORGANIC CARBON (%) F I G U R E 7 7 : R E L A T I O N B E T W E E N O R G A N I C C A R B O N A N D W A T E R D E P T H ( F R O M C O K E R A N D N I C H O L , 1 9 7 5 ) 321 may not be indicated as anomalous. In Capoose Lake where Hn accumulation has been extensive (up to 2%), and Zn l e v e l s are as great as i n any lake investigated on the plateau (600 ppm), (Zn/Mn) x 100