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Geology and geochronology of the Guichon Creek Batholith, B.C. Northcote, Kenneth Eugene 1968

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GEOLOGY AND GEOCHRONOLOGY OF THE GUICHON CREEK BATHOLITH, B.C. by KENNETH EUGENE'NORTHCOTE .A., M.Sc. U n i v e r s i t y of B r i t i s h Columbia, 1961 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n the Department of Geology We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA March 1968 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e 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 t h a t t h e L i b r a r y s h a l l m a k e 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 a n d s t u d y . I f u r t h e r a g r e e 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 t h e H e a d o f my D e p a r t m e n t o r by h i s r e p r e s e n -t a t i v e s . I t i s u n d e r s t o o d t h a t 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 n o t 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 . T h e 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 V a n c o u v e r 8, C a n a d a D e p a r t m e n t o f (p>£/n v "7 h ( i ) ABSTRACT The Guichon Creek b a t h o l i t h i s exposed w i t h i n an elongate area of 400 square m i l e s . Sedimentary rocks of Cache Creek group (Permian) and N i c o l a group (Karnian of Upper T r i a s s i c ) are in t r u d e d by the b a t h o l i t h . In the few places where outer i n t r u s i v e contacts are exposed, the ol d e r rocks have been metamorphosed to a l b i t e - e p i d o t e and hornblende h o r n f e l s and to e p i d o t e - c h l o r i t e skarn. Middle and Upper J u r a s s i c sediments, Lower Cretaceous and T e r t i a r y v o l c a n i c rocks and sediments unconformably o v e r l i e i n t r u s i v e r o c k s . P l e i s t o c e n e g l a c i a l and i n t e r g l a c i a l d e p o s i t s mantle the b a t h o l i t h l e a v -i n g l e s s than 3% of the surface of the b a t h o l i t h exposed. The Guichon Creek b a t h o l i t h i s a composite, upper mesozonal to e p i -z o n a l , i n t r u s i v e p l u t o n c o n s i s t i n g of seven major, n e a r l y c o n c e n t r i c phases. In shape i t i s an elongate, semi-concordant dome. The magma was emplaced as a c r y s t a l mush i n a s e r i e s of pulses and c r y s t a l l i z e d d u r i n g a short p e r i o d of geol o g i c time. I t i s suggested that e r o s i o n of o v e r l y i n g sedimentary and v o l c a n i c r o c k s , as i n d i c a t e d by absence of Lower J u r a s s i c s t r a t a , accompanied emplacement and c r y s t a l l i z a t i o n . o f successive phases of the b a t h o l i t h . This may e x p l a i n the a s s o c i a t i o n of mesozonal features of older phases a t the b a t h o l i t h margin w i t h e p i z o n a l features of younger inner phases. The b a t h o l i t h was emplaced by: a combination of s i d e w a l l and roof s t o p i n g , f o r c e f u l i n t r u s i o n and a s s i m i l a t i o n of ol d e r rock. There i s , t h e r e f o r e , a v a r i e t y of contacts between phases i n c l u d i n g sharp i n t r u s i v e c o n t a c t s , i n t r u s i v e contacts of d y k e - l i k e bodies and b r e c c i a t e d c o n t a c t s . Contacts between two phases, although g e n e r a l l y i n t r u s i v e , may be gradat-i o n a l i n some p a r t s of the b a t h o l i t h . Contacts between v a r i e t i e s of a phase are g r a d a t i o n a l and were not observed i n i n t r u s i v e c o n t a c t . E f f e c t s of a s s i m i l a t i o n are evident i n outer contaminated margins of Hybrid and Highland V a l l e y phases. Textures of these rocks are extremely v a r i e d and the rocks range i n composition f r o m d i o r i t e to quartz monzonite. Inner uncontaminated phases have o r d e r l y compositional and t e x t u r a l v a r i a t i o n s . The outermost uncontaminated rock i s grano-d i o r i t e and i s thought to represent c l o s e l y the composition of the o r i g -i n a l magma. Compositional d i f f e r e n c e s w i t h i n the inner phases are the r e s u l t of d i f f e r e n t i a t i o n w i t h i n the magma chamber. The most e f f e c t i v e process of d i f f e r e n t i a t i o n was upward and outward movement of a l k a l i s and s i l i c a accompanying d i f f u s i o n of v o l a t i l e s to regions of lower temp-era t u r e and pressure. The d i f f e r e n t i a l m a t e r i a l c o l l e c t e d i n cupolas and along the w a l l s of the magma chamber. Pressure buildup a t the roof of the magma chamber may have exceeded the c o n f i n i n g pressure and r e s u l t e d i n f r a c t u r i n g which allowed emplacement of magma i n t o o l d e r c r y s t a l l i n e ( i i ) phases and i n t o surrounding country rock. The number of phases may have been l a r g e l y determined by r a t e of d i f f u s i o n of v o l a t i l e s . Em-placement of d i f f e r e n t i a l magma from the margin of the chamber i n t o c o o l e r w a l l rock produced d y k e - l i k e bodies of v a r i o u s textures and compositions. U n d i f f e r e n t i a t e d magma remaining i n the magma chamber c r y s t a l l i z e d more slo w l y and produced rock of more uniform texture and composition. Twenty-six potassium-argon age determinations f o r the v a r i o u s phases of the b a t h o l i t h are centered around 198 "t 8 my. I t i s not p o s s i b l e to d i f f e r e n t i a t e among phases on the b a s i s of potassium-argon apparent ages.because v a r i a t i o n s are w i t h i n a n a l y t i c a l l i m i t s of un-c e r t a i n t y of techniques used. No i n t e r v a l of time can be given f o r p e r i o d of emplacement. A l l phases began r e t a i n i n g argon a t ap p r o x i -mately the same time 198 i 8 my. ago. The b a t h o l i t h has undergone no s i g n i f i c a n t metamorphism since that time. On the b a s i s of i s o t o p i c and geol o g i c c o n s i d e r a t i o n s , i t i s prob-able that the Guichon Creek b a t h o l i t h was emplaced approximately 200 my:, ago, a f t e r Karnian stage of Upper T r i a s s i c but p r i o r to Middle J u r a s s i c ; ( i i i ) F r o n t i s p i e c e : View from Bethlehem Copper Corpora-t i o n property southwesterly across Q u i l t a n t o n Lake i n Highland V a l l e y . ( i v ) TABLE OF CONTENTS Page ABSTRACT i TABLE OF CONTENTS i v ILLUSTRATIONS v i i i TABLES -x I INTRODUCTION 1 GENERAL INFORMATION . 1 GLACIAL FEATURES 5 PREVIOUS WORK 7 ACKNOWLEDGEMENTS 8 I I GEOLOGY OF THE BATHOLITH 10 REGIONAL SETTING .10 P r e - b a t h o l i t h i c Rocks 10 Cache Creek Group 10 N i c o l a Group 11 Metamorphism of P r e - b a t h o l i t h i c Rocks 12 Younger Rocks 15 Middle and Upper J u r a s s i c 15 Spences Bridge Group 16 Kingsvale Group 17 Kamloops Group 18 PETROLOGY OF THE GUICHON CREEK BATHOLITH 19 I n t r o d u c t i o n 19 Hybrid Phase 21 Highland V a l l e y Phase - 21 LeRoy G r a n o d i o r i t e 22 Gump Lake Phase 22 Bethlehem Phase 22 (v) Witches Brook Phase 22 Bethsaida Phase " ' 2 3 Bethlehem and Gnawed Mountain Porphyries 23 Modal Analyses 24 DESCRIPTION OF PHASES 32 Hybrid Phase r . 32 D i s t r i b u t i o n and R e l a t i o n s to Other Phases 32 Petrography . 32 Highland V a l l e y Phase 36 D i s t r i b u t i o n . V a r i e t i e s and R e l a t i o n s to Other Phases  Petrography Guichon V a r i e t y Chataway V a r i e t y LeRoy G r a n o d i o r i t e 42 D i s t r i b u t i o n and R e l a t i o n s to Other Phases 42 Petrography 42 Gump Lake Phase l- 45 D i s t r i b u t i o n and F i e l d R e l a t i o n s 45 Petrography 45 Bethlehem Phase 48 D i s t r i b u t i o n and F i e l d R e l a t i o n s 48 Petrography 48 Witches Brook Phase 50 D i s t r i b u t i o n , V a r i e t i e s and F i e l d R e l a t i o n s 50 Petrography 51 Witches Brook V a r i e t y A 52 Witches Brook V a r i e t y B 54 Witches Brook V a r i e t y C 54 Bethsaida Phase 56 D i s t r i b u t i o n and F i e l d R e l a t i o n s 56 Petrography 58 59 59 59 60 61 36 .36 37 40 Late Phases ", -. Bethlehem Porphyries Gnawed Mountain Porphyries L e u c o c r a t i c Rocks Br e c c i a s w i t h i n the B a t h o l i t h ( v i ) DEUTERIC AND HYDROTHERMAL ALTERATION 64 SPECIFIC GRAVITIES OF PHASES 65 STRUCTURE 69 EXTERNAL STRUCTURAL RELATIONS 69 INTERNAL STRUCTURAL RELATIONS 71 X e n o l i t h s 71 Contacts 71 F o l i a t i o n 72 L i n e a r s , probably F a u l t s 75 J o i n t s 78 I I I GEOCHRONOLOGY 80 INTRODUCTION 80 GUICHON BATHOLITH K/A RESULTS 81 IV 'PETROGENESIS ' - 88 ENVIRONMENT OF EMPLACEMENT 88 MODE OF EMPLACEMENT 95 Processes of Emplacement 96 Magmatic Processes 100 Suggested H i s t o r y of Emplacement of the Guichon Creek B a t h o l i t h 104 • Mesozonal Environment 104 E p i z o n a l Environment 107 Comparison of the Guichon Creek B a t h o l i t h to the S i e r r a Nevada B a t h o l i t h • 108 V SUMMARY AND CONCLUSIONS . 1 1 0 BIBLIOGRAPHY .116 APPENDIX I : GEOCHRONOLOGY 119 A. Sampling Methods 119 B. B i o t i t e Separation 119 C. Potassium Analyses 121 D. Argon Analyses 122 ( v i i ) Argon E x t r a c t i o n and Measuring Equipment 122 Operational C h a r a c t e r i s t i c s 128 P r e c i s i o n and Accuracy 129 E. D e s c r i p t i o n of B i o t i t e used i n Age Determinations 135 APPENDIX I I : DESCRIPTION OF ROCK SPECIMENS AND THIN SECTIONS 140 APPENDIX I I I : SUMMARY OF STEREOGRAM ANALYSIS 187 ( v i i i ) ILLUSTRATIONS F r o n t i s p i e c e : View southwesterly from Bethlehem Copper i i i Corporation Property Figure 1 Index Map, Guichon Creek B a t h o l i t h 2 F i g u r e 2 View from Promontory H i l l 4 F i g u r e 3 View from Gnawed Mountain 4 Fi g u r e 4 Hybrid phase c u t t i n g N i c o l a a t southwest end of. Guichon Creek B a t h o l i t h • 13 I F i g u r e 5 Hybrid phase c u t t i n g N i c o l a as f o r Figure 4 13 Figure 6 Geology of the Guichon Creek B a t h o l i t h I n Folder Figure 7 Modal Analyses 34 Figure 8 Highland V a l l e y phase, Guichon v a r i e t y 39 Figure 9 Highland V a l l e y phase, Chataway v a r i e t y 39. Fi g u r e 10 Highland V a l l e y phase, Chataway v a r i e t y 41 Figure 11 Highland V a l l e y phase, LeRoy " G r a n o d i o r i t e " . 41 Figure 12 Modal Analyses - 44 Figure 13 Gump Lake phase 46 Figure 14 Witches Brook phase c u t t i n g Hybrid phase 46 Figure 15 Bethlehem phase 49 Figure 16 Bethlehem phase 49 Figure 17 Witches Brook c u t t i n g Guichon phase 53 Figure 18 Witches Brook phase, V a r i e t y A 53 Figure 19 Witches Brook phase, V a r i e t y B 55 Figure 20 Witches Brook phase, V a r i e t y C 55 ( i x ) Figure 21 Bethsaida phase 57 Figure 22 Bethsaida phase 57 Figure 23 S p e c i f i c G r a v i t y 68 Figure 24 -• Diagramatic Cross-Section of the Guichon Creek B a t h o l i t h ' 73 Figure 25 Trends of F o l i a t i o n i n the Guichon Creek B a t h o l i t h 74 Figure 26 St r u c t u r e of the Guichon Creek B a t h o l i t h In Folder F i g u r e 27 D i r e c t i o n of S t r u c t u r a l L i n e a r s on A e r i a l Photographs 77 Figure 28 Stereograms of Poles of J o i n t s I n Folder Figure 29 Graphic Representation of K/A Age Determina-t i o n s 82 Figure 30 Environment of Emplacement of Plutons 90 Figure 31 Graphic Representation of Modes 102 Figure 32 Suggested Sequence of Events During Emplacement of the Guichon Creek B a t h o l i t h 105 Figure 33 U.B.C. K/A Laboratory Argon E x t r a c t i o n and A n a l y t i c a l System 123 Figure 34 MS10 Mass Spectrometer, U.B.C. 125 Figure 35 MSlO'Mass Spectrometer, U.B.C. 125 Figure 36 Recording U n i t of MS10 Spectrometer U.B.C. 126 Figure 37> Fusion of B i o t i t e 126 (x) TABLES TABLE I : Phases and V a r i e t i e s of I n t r u s i v e Rock 20 TABLE I I : Modal Analyses i n Weight Percent 26 TABLE I I I : Average Modes.in Weight Percent 30 , TABLE IV: Modes i n Weight Percent Measured from P o l i s h e d Slabs 31 TABLE V: Mean Values and Standard D e v i a t i o n s of S p e c i f i c G r a v i t i e s 67 TABLE V I : S p e c i f i c G r a v i t y and R e l a t i v e Age of Phases 67 TABLE V I I : Potassium A n a l y t i c a l Data 83 TABLE V I I I : Argon A n a l y t i c a l Data and Model Age 84 TABLE IX: Potassium Data from Bethlehem Copper Corporation Property (Dirom) 85 TABLE X: - Argon Data from Bethlehem Copper Corporation Property (Dirom) 85 TABLE X I : C r i t e r i a I n d i c a t i v e of Plutons of the Epizone, Mesozone and Catazone (Buddington, 1959) 89 TABLE X I I : K Analyses P r e c i s i o n 130 TABLE X I I I : Argon Analyses P r e c i s i o n . 131 TABLE XIV: Int e r - L a b o r a t o r y R e s u l t s 133 TABLE XV: Summary of Potassium and Argon Analyses Accuracy 134 -1-I INTRODUCTION The Guichon Creek b a t h o l i t h was s e l e c t e d f o r d e t a i l e d g e o l o g i c and geochronologic study because, f i r s t , i t i s an area of intense econ-omic i n t e r e s t ; second, reconnaissance work had shown i t to be a somewhat symmetrical complex b a t h o l i t h composed of rock of v a r i a b l e texture and composition; and t h i r d , a previous K/A date of 181 my. was obtained by Fo l i n s b e e from the b a t h o l i t h (Folinsbee e t a l , 1960). This date was used to define the end of the T r i a s s i c p e r i o d i n the Kulp time sca l e (Kulp, 1961, p. 1108). Baadsgaard, e t a l , (1961) subsequently reported the date to be 186 my. - 5%. GENERAL INFORMATION The Guichon Creek b a t h o l i t h comprises an area of 400 square m i l e s l y i n g e n t i r e l y w i t h i n the I n t e r i o r P l a t e a u of B r i t i s h Columbia. I t i s bounded by the Thompson, N i c o l a and Guichon Creek v a l l e y s (Figure 1 ) . The b a t h o l i t h i s traversed by Highland V a l l e y and Skuhun-Broom Creek V a l l e y which are the two major e a s t e r l y - t r e n d i n g upland v a l l e y systems. The b a t h o l i t h i s r e a d i l y a c c e s s i b l e . The town of A s h c r o f t , a t the northwest corner of the map area, and v i l l a g e of Spences Bridge, a t the j u n c t i o n of the N i c o l a and Thompson r i v e r s , are connected by C.P.R. and -2--3-C.N.R. main l i n e s and the Trans Canada highway. A secondary paved hi g h -way and C.P.R. s p u r - l i n e f o l l o w s the N i c o l a V a l l e y to the town of M e r r i t t , ten m i l e s southeast of the b a t h o l i t h . An unpaved secondary road f o l l o w s Guichon Creek V a l l e y , along the east side of- the b a t h o l i t h , n o r t h from Shulus to Savona. A secondary road from A s h c r o f t , paved f o r 28 m i l e s to s e r v i c e the Bethlehem Copper Mine, f o l l o w s Highland V a l l e y and j o i n s the Shulus-Savona road. As a r e s u l t of recent mining a c t i v i t y the e n t i r e area i s r e a d i l y a c c e s s i b l e , few places being more than two m i l e s from a road 1 or t r a i l . The Thompson and Lower N i c o l a v a l l e y s , of 1000 f e e t to 1500 f e e t e l e v a t i o n , are hot and dry i n summer and support only, a sagebrush or "scrubby" v e g e t a t i o n to an e l e v a t i o n of about 3000 f e e t . Above t h i s e l e v a -t i o n , c o o l e r temperatures and i n c r e a s i n g r a i n f a l l encourage grasslands and sparse pine f o r e s t s which become denser w i t h i n c r e a s i n g e l e v a t i o n . The higher r i d g e s , which have e l e v a t i o n s of 5000 to 6000 f e e t , and p a r t i c u l a r l y t h e i r n o r t h slopes, support denser f o r e s t growth c o n s i s t i n g of a mixture of pine, f i r and spruce. The upland v a l l e y s , above 4000 f e e t e l e v a t i o n , are grassland w i t h aspen and w i l l o w , u s u a l l y are marshy and p a r t l y flooded because of beaver dams. Most of the area i s f a i r l y f r e e of underbrush /but tree growth becomes extremely dense on moist n o r t h - f a c i n g s l o p e s . Scattered large areas of w i n d f a l l and burn make t r a v e r s i n g l o c a l l y d i f f i -c u l t but i n general the b a t h o l i t h i s f a i r l y ' e a s i l y traversed and i s a v e r y plea s a n t area i n which to work. Figures 2 and 3 are general views of the (Guichon Creek b a t h o l i t h area. Figure 2 View from Promontory H i l l at the south end of the Guichon Creek B a t h o l i t h looking n o r t h e r l y towards Skwilkwakwil, Spaist, Gnawed and Forge mountains. Figure 3 View from Gnawed Mountain on the south side of Highland V a l l e y looking southwesterly towards Pimainus Lake, Spaist and Skwilkwakwil mountains. -5-Bedrock exposures are not numerous. Probably less than 37» of the x area i s outcrop and most of that i s par t l y obscured by moss and l i c h e n . Fortunately , outcrops are f a i r l y evenly d i s t r ibu ted so that i t i s possible to map the area and project contacts from one outcrop to the next with confidence. The best exposures are found along f lanks and crests of r idges , i n abandoned meltwater channels, and to a lesser extent i n stream beds. GLACIAL FEATURES Pleistocene g l a c i a t i o n was the major geomorphological process which formed the present topographic conf igurat ion of the area. G l a c i a l and f l u v o g l a c i a l features have been modified only s l i g h t l y by : l a te r subaer ial processes. At i t s maximum thickness the Pleistocene ice sheet, moving general ly to the southeast, overrode the highest h i l l s , more than 6000 feet i n e l e v a t i o n , rounding thei r tops, deepening e x i s t i n g va l leys and accentua-t ing zones of s t ruc tura l weakness. Areas of th ick accumulation of g l a c i a l d r i f t were moulded by the ice forming what are now southeasterly trending drumlins, swales and marshes. As the thickness of the ice cap diminished, act ive g lac ie rs became confined to deeper va l leys through which now flow the Thompson and N ico la r i v e r s . Ab lat ion of ice f i e l d s at. higher leve ls resul ted i n deposit ion -6-of t h i c k d e p o s i t s of g l a c i a l m a t e r i a l i n the p r e v i o u s l y scoured upland v a l l e y s . Smaller g l a c i a l f eatures were impressed upon the landscape too. In p l a c e s , s e r i e s of 25 or more meltwater channels were cut s u b p a r a l l e l to contours of r i d g e f l a n k s a t s u c c e s s i v e l y lower l e v e l s as the i c e receded. Many streams changed t h e i r courses as a l t e r n a t e channels p r e v i o u s l y blocked by i c e became open. Kame t e r r a c e s , e s k e r s , crevasse f i l l i n g s , l a t e r a l moraines, ground moraines and e r r a t i c s were deposited during i wasting of i c e f i e l d s . These g l a c i a l f eatures r e s u l t e d i n the s w e l l and swale topography p r e v a l e n t throughout the area. During a b l a t i o n of g l a c i e r s , i c e stagnated i n major v a l l e y s and formed s e r i e s of ice-dammed l a k e s . Thick beds of white s i l t were deposited and impressions of o l d s h o r e l i n e s were l e f t on the v a l l e y w a l l s (Mathews, 1944). Streams from the highlands poured from hanging v a l l e y s i n t o the deepened major v a l l e y s , cutting.canyons i n t o steep v a l l e y w a l l s . Large a l l u v i a l fans were deposited i n ice-dammed l a k e s . P o s s i b l y other lakes were formed, by a l l u v i u m b l o c k i n g the main r i v e r channels. G r a d u a l l y the . i c e disappeared, lake water was r e l e a s e d , water f l o w diminished, meltwater channels became dry and upland streams were reduced to r e l a t i v e t r i c k l e s . The d e n d r i t i c p a t t e r n of streams was modified by s t r u c t u r e and by g l a c i a l lineaments. The r i v e r s i n the major v a l l e y s began the long process of c u t t i n g downwards through g l a c i a l m a t e r i a l , a l l u v i a l fans, and lake d e p o s i t s , forming a s e r i e s of t e r r a c e s . Uplands, w i t h t h e i r r e s t r i c t e d iwater flow remained r e l a t i v e l y unmodified, t h e i r g l a c i a l f eatures preserved. - 7 -PREVIOUS WORK The east ha l f of the Guichon Creek batho l i th was mapped on a scale of 4 miles to 1 inch by W.E. Cockf ie ld (1948), and the west ha l f of the b a t h o l i t h by S. D u f f e l l and K.C. McTaggart (1952). J . M . Carr , of the B r i t i s h Columbia Department of Mines and Petroleum Resources, has pre -pared a number of papers' descr ib ing parts of the batho l i th and adjacent areas. He has mapped i n d e t a i l the area between Gnawed and Forge mount-a i n s , i n preparat ion, and has published maps and descr ipt ions of the area adjacent to Craigmont Mine and for. part of the Thompson Va l ley between Ashcroft and Spences Bridge i n B r i t i s h Columbia Min is te r of Mines Annual Reports for 1960 and 1962, respect i ve l y . Papers have been published descr ib ing geology of mineral deposits of the Highland Va l ley area by W.H. White, R.M. Thompson and K.C. McTaggart i n 1957 and by J . M . Carr i n 1960. A map of the batho l i th south of Witches Brook was prepared by R.E. Chaplin as a B.A.Sc. t h e s i s , U . B . C , 1958, and was used as a guide during the i n i t i a l stages of f i e l d work. As a r e s u l t of intense mining a c t i v i t y i n th i s area, numerous unpublished pr ivate company maps and reports have been prepared. A K/A date of 186 my. ~t 5% was published by Baadsgaard, et a l , from the ba tho l i th i n 1961. The Geological Survey of Canada has published 12 K/A age dates on b i o t i t e for three phases of the Guichon Creek batho-l i t h . These dates appear i n G.S.C. Papers 63-17 and 64-17, prepared by -8-R.K. Wanless, G.B. Leech, and oth e r s . Concurrently w i t h K/A age deter-minations f o r t h i s t h e s i s , another age d a t i n g p r o j e c t was being c a r r i e d out, by G.E. Dirom, f o r dykes and major phases o c c u r r i n g on the Bethlehem Copper Corporation property. The r e s u l t s of h i s work form a M.A.Sc. t h e s i s prepared f o r the Department of Geophysics, U.B.C, 1965. ACKNOWLEDGEMENTS A debt of g r a t i t u d e i s owed to Dr. W.H. White, who i n i t i a t e d s e t t i n g up a K/A l a b o r a t o r y a t U.B.C. As chairman of my t h e s i s committee, he supervised f i e l d work, K/A analyses and a l l stages of p r e p a r a t i o n of t h i s t h e s i s . Dr. K.C McTaggart gave advice i n the f i e l d , on petrographic and p e t r o l o g i c problems and during p r e p a r a t i o n of the manuscript. P r o f -essor C P . E r i c k s o n designed and b u i l t the argon e x t r a c t i o n and a n a l y t i -c a l system. J.E. Harakal very a b l y supervised a l l and ran many of the argon analyses. F r u i t f u l d i s c u s s i o n s were held i n the f i e l d . w i t h Dr. J.M. Carr and w i t h G.E. Dirom i n the K/A l a b o r a t o r y . I wish to thank Dr. W.R. Danner f o r use of l a b o r a t o r y equipment (not always w i t h h i s knowledge), Drs. W.H. Mathews, R.E. D e l a v a u l t , A.J. S i n c l a i r and J.V. Ross f o r a s s i s t a n c e , c o n s t r u c t i v e c r i t i c i s m and encouragement. Very able and w i l l i n g a s s i s t a n c e was given i n the f i e l d by J.S. Northcote during both f i e l d seasons, and by Stephen Gower during the e a r l y p a r t of the f i r s t season. S p e c i a l thanks are due Mrs. S.A. -9-Northcote who typed s e v e r a l p r e l i m i n a r y d r a f t s of the t h e s i s , and f o r her patience and understanding during the years of f i e l d work and prepara t i o n of the manuscript. F i n a n c i a l support f o r K/A age determinations was obtained from N a t i o n a l Research Council grant number A1515. I am g r e a t l y indebted to Kennco E x p l o r a t i o n s , (Western) L i m i t e d f o r t h e i r f i n a n c i a l support and use of f i e l d equipment during 1963 and 1964 f i e l d seasons, and to Dr. J.A Gower of Kennco f o r h i s i n t e r e s t , encouragement and cooperation which f a c i l i t a t e d f i e l d work and p r e p a r a t i o n of the manuscript. F i n a l l y , thanks are a l s o due the many people of the Highland V a l l e y area f o r the h o s p i t a l i t y and courtesy extended to us and f o r g i v i n g per-m i s s i o n to i n v e s t i g a t e exposures on mineral claims and mining p r o p e r t i e s i n the area. Without t h e i r f u l l c ooperation, t h i s study would not have been p o s s i b l e . -10-I I GEOLOGY OF THE' BATHOLITH REGIONAL SETTING P r e - b a t h o l i t h i c Rocks The Guichon Creek b a t h o l i t h i n t r u d e s Cache Creek v o l c a n i c and s e d i -mentary rocks of M i s s i s s i p p i a n to Permian age on i t s west f l a n k i n the v i c i n i t y of Spatsum. Elsewhere i t i n t r u d e s N i c o l a v o l c a n i c and sediment-ary rock of Karnian age (Carr, 1963, pp 28-45; D u f f e l l and McTaggart, 1952, pp 15-31;.Cockfield, 1948, p 11). The i n t r u s i v e ' c o n t a c t s are" cov-ered i n most places by younger sedimentary and v o l c a n i c r o c k s , u n c o n s o l i -dated g l a c i a l d r i f t and recent stream sediment. Cache Creek Group The Cache Creek group i s i n contact w i t h the west side of the Guichon b a t h o l i t h f o r approximately 5 m i l e s i n the v i c i n i t y of Spatsum (Figure 6). The rocks of the group i n c l u d e greenstone, c h e r t , t u f f , a r g i l l i t e , l i m e -stone l e n s e s , s i l t s t o n e and greywacke composed l a r g e l y of gr a i n s of v o l c a n i c o r i g i n (Carr, 1963, pp 29-32). A t h i n halo of metamorphic rock, 1/8 to 1/2 m i l e s wide, separates Cache Creek sedimentary rock from the outer edge of the b a t h o l i t h . The th i c k n e s s of the Cache Creek group near Spatsum i s not known. D u f f e l l gives estimates of thicknesses between 15,000 and 20,000 f e e t fo (r -.11-Cache Creek group between P a v i l i o n Lake and Fraser R i v e r but t h i s e s t i -mate may be i n e r r o r because of r e p e t i t i o n of beds by f o l d i n g and f a u l t -i n g ( D u f f e l l and McTaggart, 1952, pp 16 and 17). Beds c l o s e to the b a t h o l i t h are shown by Carr to s t r i k e , n o r t h w e s t e r l y ,with moderate n o r t h e a s t e r l y dips towards the b a t h o l i t h suggesting a d i s -cordant contact r e l a t i o n s h i p . One m i l e to the west, across the Thompson R i v e r , the dips are moderate i n the opposite d i r e c t i o n i n d i c a t i n g a no r t h w e s t e r l y trending a n t i f o r m p a r a l l e l i n g the r i v e r . The Cache Creek formation i s considered' to range i n age from M i s s i -s s i p i a n to Permian ( D u f f e l l and McTaggart, 1952, p 23). N i c o l a Group Rocks of the N i c o l a group are w e l l exposed on the northwest side of the b a t h o l i t h a t Basque and east of A s h c r o f t and l e s s w e l l exposed on the south and east sides of the b a t h o l i t h . The N i c o l a group i n the type area near N i c o l a Lake c o n s i s t s p r i n c i p -a l l y of v o l c a n i c r o c k s , most of them a l t e r e d and commonly r e f e r r e d to as greenstone, which vary i n texture from f i n e - g r a i n e d or a p h a n i t i c to c o a r s e l y p o r p h y r i t i c . Color v a r i e s i n andesite and b a s a l t s from green, re d to grey. B r e c c i a s , t u f f s and agglomerates of v a r i o u s c o l o r s are a l s o common. At Basque on the west side of the b a t h o l i t h the N i c o l a group i s d i v i d e d by Carr i n t o s i x u n i t s . The lower f i v e u n i t s , comprising two-t h i r d s of the s e c t i o n , are composed of v o l c a n i c sediment, t u f f greywacke, s i l t s t o n e , limestone, c h e r t , b r e c c i a and conglomerate; the upper u n i t i s l a r g e l y greenstone (Carr, 1963, pp 32-35). -12-Because of extensive cover by younger r o c k s , there i s l i t t l e s t r u c t u r a l i n f o r m a t i o n a v a i l a b l e f o r N i c o l a rocks near the margin of the b a t h o l i t h (Figure 26). Near Basque, however, rocks of the. N i c o l a are w e l l exposed and bedding s t r i k e s n o r t h e a s t e r l y a t an angle to the b a t h o l i t h margin and dips n o r t h w e s t e r l y away from the b a t h o l i t h . On the east side of the b a t h o l i t h , one m i l e south of Witches Brook, f o l i a -t i o n i n p r e - b a t h o l i t h i c rock ( N i c o l a ? ) s t r i k e s n o r t h e r l y p a r a l l e l to the b a t h o l i t h margin and has a moderate e a s t e r l y d ip away from the batho l i t h . At these two l o c a l i t i e s the contacts may be semi-concordant. In most p l a c e s , however, the contact appears to be d i s c o r d a n t . At the n o r t west side of the b a t h o l i t h , 4 mile s east of A s h c r o f t , l a y e r i n g i n pre-b a t h o l i t h i c rock s t r i k e s n o r t h e r l y and has steep to v e r t i c a l d i p s . Beds of N i c o l a formation i n a roof remnant exposed on the west side of Glossy Mountain s t r i k e n o r t h e r l y and have v e r t i c a l d i p s . At Craigmont Mines, N i c o l a beds have a steep south d ip and are cut a t a small angle by i n -t r u s i v e b a t h o l i t h i c rock (Rennie, 1962, p 50; Drummond, 1965, p 117). Older rocks a t the b a t h o l i t h margin are metamorphosed and cut by " g r a n i -t i c " dykes (Figures 4 and 5 ) . Metamorphism of P r e - b a t h o l i t h i c Rocks I n t r u s i o n of the b a t h o l i t h has r e s u l t e d i n metamorphism of pre-b a t h o l i t h rocks to skarn and h o r n f e l s . The width of the metamorphic halo i s 1/8 to 1/2 mile wide w i t h higher grade metamorphism on the east Figure 5 Hybrid phase c u t t i n g N i c o l a as f o r Figure 4. side than on the west side of the b a t h o l i t h . Metamorphism varies from place to place. On the north and west sides of the b a t h o l i t h the older rock i s epidotized, c h l o r i t i z e d , weakly carbonatized and s i l i c i f i e d . Metamorphism becomes more intense near i n t r u s i v e contacts forming s i l i c e o u s hornfels, epidote skarn and zones r i c h i n disseminated p y r i t e and magnetite. The metamorphic rocks on the west side of the b a t h o l i t h are predominantly of the e p i d o t e - a l b i t e hornfels f a c i e s of metamorphism. Two areas at l e a s t 2 miles long on the east margin of the b a t h o l i t h are underlain by rock r e f e r r e d to as gabbro g e n e t i c a l l y r e l a t e d to the Guichon Creek b a t h o l i t h i n e a r l i e r reports ( C o c k f i e l d , 1948, pp 16 and 17). I t i s suggested that these rocks represent r e c r y s t a l l i z e d N i c o l a rather than gabbro. The rock i s r e l a t i v e l y fine-grained compared to in t r u s i v e rock, i s dark and shows tex t u r a l and compositional v a r i a t i o n s . I t consists predominantly of labradorite with p o i k i l o b l a s t i c hornblende containing augite, very minor amounts of i n t e r s t i t i a l quartz and opaque grains associated with mafic minerals. Tremolite or a c t i n o l i t e may be present instead of hornblende, and some sections show abundant sphene and traces of garnet. Some thi n sections show marked preferred o r i e n t a t i o n of p l a g i o c l a s e ; others show no preferred o r i e n t a t i o n . In some sections small anhedral grains of pl a g i o c l a s e , hornblende and sphene form a "paving block" texture. Mafic minerals are anhedral, p o i k i l o b l a s t i c and i n t e r s t i t i a l to p l a g i o c l a s e . Hornblende or tremolite veins are common. This rock belongs to the hornblende hornfels f a c i e s of contact metamorphism. -15-Temperature of country rock a t the contact can be estimated from the degree of thermal metamorphism which grades from a l b i t e - e p i d o t e h o r n f e l s to hornblende h o r n f e l s f a c i e s . Maximum temperature of country rock a t the contact would be about 650°C i f b u r i e d to a depth of 6 k i l o -meters or 550°C i f buried to a depth of 1.2 k i l o m e t e r s (Winkler, 1965, p 63). Younger Rocks I n t r u s i v e rocks of the Guichon Creek b a t h o l i t h are unconformably o v e r l a i n by sediments of Middle and Upper J u r a s s i c age, Spences Bridge group v o l c a n i c s of Lower Cretaceous age, T e r t i a r y v o l c a n i c s of probable Eocene age and f i n a l l y by unconsolidated P l e i s t o c e n e g l a c i a l and Recent d e p o s i t s . Middle and Upper J u r a s s i c Middle and Upper J u r a s s i c s t r a t a o v e r l i e the northwest p a r t of the Guichon Creek b a t h o l i t h and extend northward, as a zone 14 m i l e s long and 5 m i l e s wide centered on the town of A s h c r o f t (Carr, 1963, p 37; Crickmay, 1930; D u f f e l l and McTaggart, 1957, pp 31-33). Unaltered J u r a s s i c s h a l e , conglomerates and sandstones are exposed on the west f l a n k of Glossy Mountain. The J u r a s s i c s t r a t a have been described i n d e t a i l by Crickmay who d i v i d e s them i n t o two s e r i e s w i t h t o t a l t h i c k n e s s of 4900 f e e t . The -16-lower s e r i e s , r e f e r r e d to as the Thompson s e r i e s , 1800 f e e t t h i c k , c o n s i s t s of a b a s a l conglomerate o v e r l a i n by calcareous arkose and, forming the upper three-quarters of the s e c t i o n , b lack shale w i t h minor sandstone. The upper s e r i e s , r e f e r r e d to as the A s h c r o f t s e r i e s , 3100 f e e t t h i c k , has conglomerate a t i t s base o v e r l a i n by. b l a c k shale w i t h i n t e r c a l a t e d sandstone beds (Crickmay, 1930, p 37). The conglomerates c o n t a i n boulders of s i m i l a r texture and composition to the Guichon batho-l i t h , f i n e - g r a i n e d p o r p h y r i t i c quartz d i o r i t e , quartz porphyry and f e l d -spar porphyry. I t a l s o contains boulders of cherty r o c k s , greenstone, p o r p h y r i t i c v o l c a n i c r o c k s , and some sandstone (Carr, 1963, p 37). On the b a s i s of pelecypod and ammonite f o s s i l s , these s t r a t a are considered to range from Middle to Upper J u r a s s i c (Crickmay, 1930, p 37). Spences Bridge Group The Spences Bridge group of v o l c a n i c s t r a t a unconformably o v e r l i e s the southwest f l a n k of the Guichon b a t h o l i t h . I t forms a b e l t 2 to 15 m i l e s wide extending from the southwest corner of the map area, n o r t h -w e s t e r l y f o r a t l e a s t 75 m i l e s . I t crops out along the northeast side of N i c o l a V a l l e y and crosses the Thompson R i v e r between Pimainus and Inkikuh creeks where i t unconformably o v e r l i e s rocks of Cache Creek group. Hybrid i n t r u s i v e r o c k s , adjacent to the east margin of Spences Bridge group, are cut by swarms of s o u t h e a s t e r l y - and e a s t e r l y - t r e n d i n g p o r p h y r i t i c feeders of the Spences Bridge group. Rocks of Spences Bridge group are lavas and p y r o c l a s t i c rocks of a -17-v a r i e t y of l i t h o l o g i e s and c o l o r s . Minor amounts of conglomerate, sand-stone and w a t e r - l a i n t u f f are a l s o present. The v o l c a n i c rocks are •mainly p o r p h y r i t i c andesite and d a c i t e w i t h l e s s e r amounts of r h y o l i t e and b a s a l t . Agglomerates and b r e c c i a s are important c o n s t i t u e n t s i n the sequence ( D u f f e l l and McTaggart, 1952, pp 52-54). W.A. B e l l , of the G e o l o g i c a l Survey, e s t a b l i s h e d the age of the Spences Bridge, by f o s s i l p l a n t s , as A p t i a n stage of Lower Cretaceous ( D u f f e l l and McTaggart, 1952, pp 54-55). Ki n g s v a l e Group The K i n g s v a l e group crops out a t the southern edge of the map-area, unconformably o v e r l y i n g N i c o l a rocks i n the v i c i n i t y of Craigmont Mine. Outside of the map-area, where i t i s estimated to be 3600 f e e t t h i c k , i t unconformably o v e r l i e s the Spences Bridge group ( D u f f e l l and McTaggart, 1952, pp 55-58). The K i n g s v a l e group i s composed of r h y o l i t e , a n d e s i t e , b a s a l t , b r e c c i a and agglomerate, and t u f f , w i t h b a s a l t and b a s a l t b r e c c i a pre-dominating. Arkose and conglomerate are not abundant ( C o c k f i e l d , 1948, pp 19-21). P l a n t f o s s i l evidence from outside the map-area i n d i c a t e s the Kings-v a l e group was deposited during A l b i a n stage of Lower Cretaceous ( D u f f e l l and McTaggart, 1952, p 58).. A K/A age of 80 my. by the G e o l o g i c a l Survey of Canada on b i o t i t e from K i n g s v a l e v o l c a n i c s i n d i c a t e s an Upper Creta-ceous age f o r t h i s group (Lowden, J.A., 1963, p 19). -18-Kamloops Group S t r a t a of the Kamloops group measure 3500 f e e t i n thickness i n a pl a t e a u to the nor t h of the Guichon Creek b a t h o l i t h . Nearly f l a t - l y i n g flows unconformably o v e r l i e J u r a s s i c shales and cap many of the high mountains i n the area. V o l c a n i c plugs and dykes cut the b a t h o l i t h a t s c a t t e r e d l o c a t i o n s , notably a t the Simons zone of the Bethlehem Copper property, on the south slope of Forge Mountain, a t two places on the r i d g e on the south side of Highland V a l l e y , and on the east side of Gypsum Mountain. Some plugs are fragmental, others have a chalky appear-ance. A few have s t e e p l y d i p p i n g to v e r t i c a l , t h i n l y laminated " f l o w l a y e r i n g " . The v o l c a n i c rocks of the Kamloops group c o n s i s t mainly of b a s a l t , l e s s e r andesite and minor r h y o l i t e . A s s ociated p y r o c l a s t i c s range from t u f f to agglomerate. The lavas are commonly v e s i c u l a r or amygdaloidal, mainly black but in c l u d e r e d , brown, grey, green, mauve, buff and white v a r i e t i e s ( D u f f e l l and McTaggart, 1952, pp 66-68). Two K/A dates of 49 and 51 "t 3 my. on una l t e r e d b i o t i t e from a fragmental r h y o l i t e . o n the south side of Highland V a l l e y i n d i c a t e t h a t some of the v o l c a n i c rocks are Eocene (White e t a l , 1967, p 686). Mathews (1963) obtained four i s o t o p i c dates w i t h a range i n age of 45 to 53 my., middle Eocene, from three basins of v o l c a n i c and sedimentary rocks ( P r i n c e t o n , Kamloops Lake and Francois Lake b a s i n s ) . H i l l s and Baadsgaard (1967) r e s o l v e d e a r l i e r p a l e o b o t a n i c a l problems i n these s t r a t a and obtained f i f t e e n K/A dates ranging from 47 to 52 my. These - 1 9 -age determinations represent T e r t i a r y v o l c a n i c rock from e i g h t l o c a l i -t i e s i n B.C. and confirm a middle Eocene age f o r the Kamloops group. PETROLOGY-OF THE GUICHON CREEK BATHOLITH I n t r o d u c t i o n The i n t r u s i v e rocks of the Guichon Creek b a t h o l i t h were d i v i d e d i n t o s e v e r a l d i s t i n c t i v e u n i t s by t h e i r f i e l d r e l a t i o n s h i p s , t e x t u r e , m i n e r a l content and m i neral composition. Some u n i t s are c l e a r l y i n t r u s i v e i n t o others and i l l u s t r a t e t h e i r r e l a t i v e age by dykes, contact b r e c c i a t i o n , x e n o l i t h s and l e s s commonly by c h i l l e d c o n t a c t s . Other u n i t s show only a gradation from one to another. A u n i t may, however, show i n t r u s i v e c o ntacts w i t h another u n i t i n one area and g r a d a t i o n a l contacts w i t h the same u n i t elsewhere. In order to d i s t i n g u i s h between u n i t s w i t h i n t r u s -i v e contacts and those showing only g r a d a t i o n a l c o n t a c t s , the terms "phases" and " v a r i e t i e s " are used r e s p e c t i v e l y . Phases are separated a t l e a s t l o c a l l y by sharp contacts where, g e n e r a l l y , r e l a t i v e ages can be determined. A v a r i e t y i s a s u b d i v i s i o n of a phase which has a grada-t i o n a l contact w i t h that phase. Figure 6 shows the a r e a l extent of phases and v a r i e t i e s of the b a t h o l i t h which are as f o l l o w s : -20-TABLE I : Phases and V a r i e t i e s of I n t r u s i v e Rock R e l a t i v e l y Old (1) Hybrid phase: quartz d i o r i t e , g r a n o d i o r i t e (2) Highland V a l l e y phase: Guichon v a r i e t y : quartz d i o r i t e , g r a n o d i o r i t e Chataway v a r i e t y : g r a n o d i o r i t e , quartz monzonite (3) LeRoy " g r a n o d i o r i t e " : g r a n o d i o r i t e , quartz monzonite Intermediate Age (4) Gump Lake phase: g r a n o d i o r i t e , quartz monzonite (5) Bethlehem phase: g r a n o d i o r i t e , quartz monzonite (6) Witches Brook phase V a r i e t y A: g r a n o d i o r i t e V a r i e t y B: g r a n o d i o r i t e V a r i e t y C: g r a n o d i o r i t e , quartz monzonite, g r a n i t e (7) Bethlehem Porphyries R e l a t i v e l y Young (8) Bethsaida phase: quartz monzonite, g r a n o d i o r i t e (9) Gnawed Mountain Po r p h y r i e s , younger Bethlehem Porphyries and a s s o c i a t e d i n t r u s i v e B r e c c i a s (10) L e u c o c r a t i c dykes and i r r e g u l a r shaped bodies -21-The Guichon Creek b a t h o l i t h i s a semi-concordant composite i n t r u s - ' i v e pluton c o n s i s t i n g of seven n e a r l y c o n c e n t r i c major phases which i n general decrease i n r e l a t i v e age inwards. Hybrid Phase The Hybrid phase i s p e r i p h e r a l to the b a t h o l i t h and i s i n t r u s i v e i n t o Cache Creek and N i c o l a group r o c k s . I t appears to have been contam-i n a t e d by p r e - b a t h o l i t h rock w i t h the r e s u l t that there i s g r a d a t i o n i n r e l a t i v e p r o p o r t i o n and composition of minerals towards the p e r i p h e r y . Composition i s predominantly quartz d i o r i t e but shows v a r i a t i o n from d i o r i t e to quartz monzonite. The Hybrid phase i s cut by dykes and i r r e g -u l a r bodies of Highland V a l l e y and Witches Brook phases. The Hybrid phase i s the o l d e s t i n t r u s i v e rock of the b a t h o l i t h . Highland V a l l e y Phase The Highland V a l l e y phase forms a c o n c e n t r i c r i n g w i t h i n Hybrid phase. The Highland V a l l e y phase c o n s i s t s of two v a r i e t i e s c a l l e d Guichon and Chataway. The Guichon v a r i e t y shows e f f e c t s of contamination by o l d e r rock and ranges i n composition from quartz d i o r i t e to g r a n o d i o r i t e . The Chataway v a r i e t y occurs mainly i n the south p a r t of the b a t h o l i t h whereas the Guichon v a r i e t y i s abundant i n the n o r t h . Guichon and Chataway v a r i e t i e s cut the Hybrid phase as dykes or form a m a t r i x be-tween b r e c c i a t e d fragments of Hybrid phase. The Highland V a l l e y phase i s younger than the Hybrid phase. LeRoy G r a n o d i o r i t e LeRoy g r a n o d i o r i t e forms i r r e g u l a r d y k e - l i k e bodies i n Chataway v a r i e t y . There i s no w e l l defined mass of LeRoy g r a n o d i o r i t e as there i s f o r the major phases. A diagonal p a t t e r n on Figure 6 marks areas where d y k e - l i k e bodies of LeRoy are abundant. Gump Lake Phase The c o n c e n t r i c c o n f i g u r a t i o n of successive phases of the Guichon b a t h o l i t h i s i n t e r r u p t e d by the Gump Lake phase which covers an area of 9 square m i l e s on the east side of the b a t h o l i t h . The Gump Lake phase i s predominantly g r a n o d i o r i t e and quartz monzonite. I t i s cut by and i s theref o r e o l d e r than the Witches Brook phase. Bethlehem Phase The Bethlehem phase almost completely e n c i r c l e s a c e n t r a l core of the b a t h o l i t h . This phase i s of uniform g r a n o d i o r i t e composition. Xeno-l i t h s of the Guichon v a r i e t y occur i n the Bethlehem phase, so Bethlehem i s c l e a r l y the younger. Witches Brook Phase The c o n c e n t r i c c o n f i g u r a t i o n of major i n t r u s i v e phases i s f u r t h e r i n t e r r u p t e d by v a r i e t i e s of the Witches Brook phase. There i s no w e l l d e f i n e d mass of Witches Brook as there i s f o r other major phases. Witches Brook occurs w i t h i n the older phases throughout the b a t h o l i t h but i s most abundant on the ea s t side a t Witches Brook, the stream a f t e r which the -23-phase was named. A second diagonal p a t t e r n on Figure 6 marks areas where Witches Brook phase i s most abundant. T e x t u r a l l y t h i s phase c l o s e l y resembles Bethlehem but shows wide v a r i a t i o n s i n g r a i n s i z e and composition from g r a n o d i o r i t e to g r a n i t e . I r r e g u l a r masses and dyke-l i k e bodies of Witches Brook cut Guichon and Chataway v a r i e t i e s and Hybrid and Gump Lake phases; t h e r e f o r e , the Witches Brook phase i s of intermediate age. Bethsaida Phase The Bethsaida phase forms a c e n t r a l core of the Guichon Creek b a t h o l i t h . I t i s predominantly of quartz monzonite composition. The Bethsaida phase has c h i l l e d contacts a g a i n s t Bethlehem'phase and Guichon v a r i e t y , so i s c l e a r l y the youngest of these phases. Bethlehem and Gnawed Mountain Porphyries Porphyry dykes and i r r e g u l a r porphyry bodies, many c l o s e l y assoc-i a t e d w i t h pipe b r e c c i a s , occur i n the Bethsaida, Bethlehem and Highland V a l l e y phases. These porphyries are b e l i e v e d to be g e n e t i c a l l y r e l a t e d to the young phases of the b a t h o l i t h . A notable swarm of n o r t h e r l y t r e n d i n g porphyry dykes, at l e a s t 10 m i l e s long and 3 to 5 m i l e s wide, crosses Highland V a l l e y on and to the west of Bethlehem Copper Corpora-t i o n property (Carr, 1960, pp 71-73). -24-Modal Analyses Rock specimens considered to be most r e p r e s e n t a t i v e of each phase and v a r i e t y were used to e s t a b l i s h modes and consequently rocks of each phase or v a r i e t y can be expected to show greater compositional v a r i a t i o n than i n d i c a t e d by Table I I . Standard t h i n s e c t i o n s were used f o r modal analyses and from 3000 to 5500 p o i n t s per t h i n s e c t i o n were counted w i t h a S w i f t & Son p o i n t counter. P o i n t counts were made of a t l e a s t s i x t h i n s e c t i o n s f o r each phase or v a r i e t y , except Gump Lake phase f o r which there were three. A c h a r t f o r judging the r e l i a b i l i t y of p o i n t counting r e s u l t s i n d i c a t e s a p r e c i s i o n w i t h i n 2"L f o r those many f i n e - g r a i n e d specimens where g r a i n s i z e i s smaller than point-count spacing (Van Der P l a s and Tobi, 1965, pp 87-90). Modes e s t a b l i s h e d by counts of s i n g l e t h i n s e c t i o n s f o r coarse-grained phases are not accurate because the rocks are very heterogeneous. I t was p a r t i c u l a r l y d i f f i c u l t to determine modes f o r o r t h o c l a s e i n coarse-grained phases where i t occurs as i r r e g u l a r l y d i s t r i b u t e d p o i k i -l i t i c masses commonly two or more centimeters i n diameter. P o l i s h e d s l a b s , 2 1/2 to more than 4 inches i n l a r g e s t diameter,-on which ortho-c l a s e was s t a i n e d y e l l o w , were measured i n the f o l l o w i n g way. The p o l i s h e d slabs were photographed i n d a y l i g h t on 35 mm Kodak Kodachrome I I f i l m . The c o l o r e d s l i d e s were p r o j e c t e d onto a g r i d screen w i t h g r i d -25-spacing made s u i t a b l e to the g r a i n s i z e by moving the p r o j e c t o r c l o s e r to or farther from the g r i d . S i x thousand p o i n t s were counted on each of two faces which were a t l e a s t 1/2 i n c h apart f o r each s l a b . Using the slab method, p l a g i o c l a s e and quartz were p a r t i c u l a r l y d i f f i c u l t to d i s t i n g u i s h but a good check was provided f o r o r t h o c l a s e content. P l a g i c l a s e was st a i n e d pink on a few t r i a l slabs but t h i s method was not s u c c e s s f u l because c o l o r c o n t r a s t was poor viewed c l o s e to the screen. Modes obtained from t h i n s e c t i o n s f o r each phase are l i s t e d i n Table I I . Figures 7 and 12 are ternary diagrams showing the p l o t of each mode i n terms of quartz, o r t h o c l a s e and p l a g i o c l a s e ( o l i g o c l a s e -andesine) content and c l a s s i f i c a t i o n of the rock (Johannsen, V o l . 1, p 144). For purposes of the ternary diagrams modal percentages have been r e c a l c u l a t e d so that o r t h o c l a s e + p l a g i o c l a s e + quartz = 100%. For that reason the percent quartz, o r t h o c l a s e or p l a g i o c l a s e read o f f the f i g u r e s w i l l not agree w i t h percentages l i s t e d i n Table I I . , TABLE.II: Modal Analyses i n Weight Percent Hyb r i d Phase K63-13 P l a g i o c l a s e 53.75 Orthoclase 4.39 Quartz 19.45 B i o t i t e 8.30 Hornblende 11.18 Augite 1.43 Opaque 1.37 Sphene 0.08 A p a t i t e 0.02 Z i r c o n 0.03 K64-156a K64-15 49.86 51.40 10.09 2.49 20.20 23.27 6.49 10.50 NC 9.55 10.83 0.82 2.47 1.98 NC NC 0.07 NC NC NC K64-15 K64-10 48.55 70.29 4.95 0.13 25.12 7.27 7.66 2.99 12.10 5.66 0.08 10.67 1.34 2.35 0.09 0.52 NC . 0.06 0.12 0.03 K64-10-I K63-224a 55.23 54.04 0.07 0.12 19.32 10.35 6.67 8.66 11.76 22.02 3.42 0.04 3.36 4.70 NC . NC 0.17 0.09 NC NC ro i Guichon V a r i e t y K63-223 K63-223-II K63-223-II P l a g i o c l a s e 45.75 45.98 . 47.79 Orthoclase 12.29 14.32 16.03 Quartz 20.68 19.80 18.00 B i o t i t e 9.54 8.09 5.06 Hornblende 8.85 8.47 10.68 Augite 0.31 1.17 1.74 Opaque 1.86 1.59 0.24 Sphene 0.65 0.47 0.40 A p a t i t e 0.06 0.08 0.02 Z i r c o n 0.03 0.03 0.03 K63-223-II K64-50aV K63-33b-I K63-136-I K63-196 47.96 52.32 .48.36 52.66 58.93 15.47 11.42 8.24 2.71 NC 18.55 18.75 17.55 16.32 11.70 4.22 5.92 i o.4i; 16.95 13.22 11.36 9.68 10.05'; 1.49 4.61 0.26 0.47 1.06 7.94 6.73 1.51 2.38 4.08 1.94 4.02 0.45 0.03 0.24 NC 0.79 0.02 NC • NC NC NC 0.20 0.03 NC NC NC TABLE I I - c o n t 1 d Chataway V a r i e t y K64-116a K64-48-I K63-204-P l a g i o c l a s e 55.69 54.18 52.89 Orthoclase 6.90 7.13 11.65 Quartz 23.33 23.65 22.12 B i o t i t e 6.26 7.49 6.43 Hornblende 6.02 5.49 4.98 Augite NC NC NC Opaque 1.42 1.78 1.81 Sphene 0.07 0.28 0.05 A p a t i t e 0.18 0.02 0.07 Z i r c o n 0.10 NC NC LeRoy Gr a n o d i o r i t e K64-54 K64-47aIII K63-202V P l a g i o c l a s e 43.69 58.64 56.19 Orthoclase 17.53 2.48 9.02 Quartz .25.61 27.10 23.90 B i o t i t e 5.80 3.69 3.54 Hornblende 4.77 6.77 4.97 Augite NC NC NC Opaque 2.46 • 1.13 2.15 Sphene 0.11 0.16 0.20 A p a t i t e 0.02 0.03 0.02 Z i r c o n NC NC NC K63-44 K63-185 K63-204-IV K63-34 63.49 48.32 62.20 43.62 4.89 21.98 8.82 15.17 13.15 16.06 17.47 28.69 5.15 2.91 5.37 2.72 11.31 7.95 4.57 6.96 NC NC NC NC 1.29 2.51 1.45 2.59 0.50 0.20 0.09 0.25 0.23 0.06 0.02 NC NC ' NC ' NC NC K63-37 K63-220 K64-101 42.91 57.23 45.80 19.37 9.32 14.86-28.01 17.75 25.59 4.22 1.81 5.95 3.83 12.39 5.62 NC NC NC 1.21 1.39 1.69 0.24 0.09 0.49 0.17 0.02 NC 0.03 NC NC TABLE I I - cont'd Gump Lake Phase K64-98-I K64-89 P l a g i o c l a s e 36.97 48.72 Orthoclase 16.08 11.98 Quartz 38.87 32.64 B i o t i t e 5.67 4.81 Hornblende 0.90 0.49 Augite NC NC Opaque 1.26 1.26 Sphene NC 0.05 A p a t i t e 0.10 0.05 Z i r c o n 0.16 NC Bethlehem Phase K63-192 P l a g i o c l a s e 58.95 Orthoclase 10.82 Quartz 19.70 B i o t i t e 0.51 Hornblende 7.05 Augite NC Opaque 2.94 Sphene NC A p a t i t e 0.02 Z i r c o n NC K63-189aII K63-188a 58.92 56.53 15.51 8.12 19.26 23.83 1.98 5.37 2.66 2.67 NC NC 1.24 2.80 0.43 0.51 NC 0.17 NC NC K64-91 49.95 11.02 29.11 6.67 0.95 NC 2.62 NC 0.18 NC K64-61 63.47 5.98 20.01 5.73 2.48 NC 2.05 0.20 0.07 NC K64-60a 63.04 8.67 19.57 1.55 3.76 NC 2.84 0.34 0.23 NC K63-115 58.42 12.70 18.26 1.88 5.85 NC 2.00 0.65 0.14 0.10 K64-186a 53.76 7.82 25.06 5.12 5.83 NC 2.33 NC 0.04 0.03 TABLE I I - cont'd Witches Brook Phase K64-105-I K63-171 K64-102 K64-111 P l a g i o c l a s e / 39.76 ' 52.11 * 43.03 ' 46.13 Orthoclase 20.05 10.44 18.20 15.89 Quartz 27.92 25.74 26.86 26.72 B i o t i t e 3.34 5.18 5.50 5.18-Hornblende' 5.33 3.78 3.81 4.71 Augite NC 0.03 NC NC Opaque 1.38 1.99 1.77 1.06 Sphene 2.13 0.31 0.77 0.30 A p a t i t e 0.03 0.03 0.02 NC Z i r c o n NC 0.05 NC NC K64-203 K63-84 K63-28a K64 r17 K64 T17 K63 7222 50.93 40.79 39.28 28.08 30.26 31.00 12.14 18.87 24.28 26.20 25.44 29.42 27.84 29.09 25.50 43.19 41.53 36.61 5.99 5.04 4.88 1.86 2.02 2.41 2.23 5.57 3.47 NC NC NC NC 0.30 0.68 0.04 NC NC 0.65 1.10 1.71 . 0.64 0.75 0.56 0.18 0.23 0.11 NC NC NC NC NC NC NC NC NC 0.03 NC 0.08 NC NC NC 'Bethsaida Phase K64-64 K63-115a K63-238a K63-239 K63-231 K63- 187 P l a g i o c l a s e 46.21 62.16 57.97 37.62 52.07 56. 67 Or thoclase 5.88 13.93 14.55 5.28 10.76 12. 95 Quartz 35.22 16.38 22.08 45.71 30.14 26. 81 B i o t i t e 11.82 4.49 3.62 10.17 4.82 2. 71 Hornblende 0.42 0.55 0.14 0.81 0.29 0. 18 Augite NC NC NC NC NC NC Opaque 0.44 2.05 1.24 0.25 1.26 0. 56 Sphene NC 0.20 0.23 0.10 0.33 o. 05 A p a t i t e 0.02 0.21 0.18 NC 0.30 o. 07 Z i r c o n NC 0.05 NC 0.05 0.03 NC TABLE I I I : Average Modes i n Weight Percent (Summary of Table I I ) Hybrid Guichon Chataway LeRoy Gump Lake 1 Witches Brook Bethlehem Bethsaida P l a g i o c l a s e 54.72 49.91 54.34 50.72 45.06 40.16 49.02 52.11 Orthoclase 3.18 10.04 10.93 12.10 13.03 20.10 9.95 10.56 Quartz 17.85 17.65 20.64 . 24.67 33.55 31.02 20.81 29.39 B i o t i t e 7.32 9.16 5.19 4.17 5.72 4.14 3.16 6.27 Hornblende 10.35 8.14 6.76 6.40 0.78 2.89 4.33 0.40 Augite 3.89 2.46 - - - 0.11 - -Opaque 2.51 2.20 1.84 1.67 1.71 1.16 2.31 0.97 Sphene 0.09 0.38 0.22 0.22 0.02 0.40 0.30 0.15 A p a t i t e 0.06 0.02 0.08 0.04 0.08 0.01 0.10 0.13 Z i r c o n . 0.03 0.04 0.01 0.05 0.02 0.02 0.02 CI-TABLE IV: Modes i n Weight Percent Measured From P o l i s h e d Slabs (Random Speci-mans) Guichon Chataway P l a g i o c l a s e 58 54 • Orthoclase 9 19 . Quartz 6 13 P l a g i o c l a s e .52 60 Orthoclase 10 13 Quartz 6 14 P l a g i o c l a s e 52 Orthoclase 17 Quartz 14 P l a g i o c l a s e 45 Orthoclase 22 Quartz 20 Gump Lake Bethlehem Bethsaida 37 63 54 25 10. 5 28 15 22 39 61 58 26 11 13 26 17 22 36 57 64 33 13 14 22 19 18 40 54 52 31 12 19 22 23 22 P l a g i o c l a s e Orthoclase Quartz 42 27 23 54 18 20 -32-DESCRIPTION OF PHASES Hybrid Phase D i s t r i b u t i o n and R e l a t i o n s to Other Phases The Hybrid phase i s everywhere p e r i p h e r a l to the b a t h o l i t h and i s i n t r u s i v e i n t o Cache Creek "and N i c o l a group r o c k s . I t forms a r i m of g r a n i t i c rock which shows a grad a t i o n w i t h r e s p e c t to the periphery i n texture and r e l a t i v e abundance of i t s main m i n e r a l s . Far from contacts w i t h s t r a t i f i e d rocks the Hybrid phase g e n e r a l l y shows f a i r l y uniform textures and compositions but t h i s i s not everywhere tr u e . (For example, immediately west of S p a i s t and Skwilkwakwil mountains, s e v e r a l m i l e s from e x i s t i n g contact w i t h older r o c k s , hornblende-rich h y b r i d rock has a s t r o n g l y f o l i a t e d , l o c a l l y s w i r l e d s t r u c t u r e . Such areas might i n d i c -ate the magma was clos e to the ro o f of the magma chamber. The Hybrid phase i s cut b y . i r r e g u l a r dykes and masses of a t l e a s t two younger phases as w e l l as by a p l i t i c to pegmatitic m a t e r i a l . The Highland V a l l e y and Witches Brook phases cut Hybrid rocks as dykes and cement b r e c c i a of the Hybrid phase a t s e v e r a l places on the south and east sides of the b a t h o l i t h . Petrography No p a r t i c u l a r specimen can be designated as t y p i c a l of the Hybrid -33-phase. Specimens, by v i s u a l estimate of mineral content, range from hornblendite through d i o r i t e to quartz d i o r i t e and g r a n o d i o r i t e . Most of the h y b r i d rocks are quartz d i o r i t e . They are e q u i g r a n u l a r , holo-c r y s t a l l i n e , c o n s i s t i n g of quartz, o r t h o c l a s e , b i o t i t e , augite and hypersthene i n some t h i n s e c t i o n s . Accessory minerals i n c l u d e sphene, z i r c o n , a p a t i t e , magnetite and hematite. Sulphides which were observed i n some.specimens are p y r i t e , c h a l c o p y r i t e and r a r e l y b o r n i t e and molybdenite. Modes f o r seven specimens thought to be f a i r l y r e p r e s e n t a t i v e of the most abundant hy b r i d types are p l o t t e d on a t e r n a r y diagram, Figure 7a. S i x modes f a l l w i t h i n quartz d i o r i t e and one w i t h i n g r a n o d i o r i t e p a r t s of the diagram. Modes l i s t e d on Table I I show a range i n quartz -content from 7.27% to 25.12%, i n o r t h o c l a s e content from 0.12% to 10.09% and i n p l a g i o c l a s e content from 48.55% to 70.29%. T o t a l mafic content ranges from 17.32% to 30.72% w i t h an average of 21.56%. P l a g i o c l a s e i s euhedral to subhedral and shows p r e f e r r e d o r i e n t a -t i o n i n most t h i n s e c t i o n s . Measured composition using a l b i t e twin ( X A O I O M a x X i n zone 1010; X/\010_La) and carlsbad-albite.methods of measurement i n d i c a t e a range of composition from A ^ 7 to An^g w i t h An3g to A n ^ being most common. Normal zoning;was observed w i t h cores An^g and margins An27. A l b i t i c a l t e r a t i o n of the margins of p l a g i o c l a s e i s very common. Granophyric intergrowths of quartz and a l b i t e commonly occur i n c l e a r a l b i t i c margins surrounding more c a l c i c cores clouded •with s a u s s u r i t e and s e r i c i t i c a l t e r a t i o n . -34-Modal Analyses 100% Quartz 100% Quartz 80/-7 Quartz Diorite -7 , . ^ / /Granite /Qfz. Monzonite 'Granodiorite\ ~~r r : * \ _ / < i J • , __\_) i \_ 10 20 30 40 SO 60 70 60 90 10/ / Granite ^Qtz. Monzonite \Gnanod]orite\_ \\q 100% Orthoclose 100% 100% Plagioclase Orthoclase 10 20 30 40 5 0 - 60 70 80 90 100% Plagioclase (o) Hybrid Phase (b) Guichon Variety • Th in - sec t ion - 9 stained slab X Average Composition 100% Quartz 100 % Quartz Quartz Diorite 3 0 Z _ i L l r t / /Granite iQtz. Monzonite \ Grano<Jiorite\ \ , n / t ~ r A 10 20 30 40 50 60 70 80 90 100 % Orthoclase 100 % 100 % Plagioclase Orthoclase 10 20 30 40 50 6 0 70 80 90 100 % Plagioclase (c) Chataway Variety (d) Le Roy Granodiorite Figure 7 -35-Orthoclase may be present i n small amounts. I t . i s i n t e r s t i t i a l , anhedral and i s clouded by a grey to s l i g h t l y reddish-brown a l t e r a t i o n . Quartz i s anhedral, everywhere occurs i n t e r s t i t i a l l y or as graphic intergrowths w i t h a l b i t e and u s u a l l y shows f r a c t u r e s and s t r a i n e d e x t i n c t i o n . The mafic m i n e r a l s , hornblende, b i o t i t e , augite and r a r e hypers-thene vary i n r e l a t i v e abundance. Most mafic g r a i n s are subhedral to anhedral w i t h ragged o u t l i n e s and tend to form aggregates. Augite commonly forms i s o l a t e d rounded anhedral g r a i n s i n subhedral hornblende and i s the r e s u l t of incomplete r e a c t i o n of the magma w i t h augite to form hornblende. The amount of augite present i s v a r i a b l e but u s u a l l y o n ly minor amounts remain. B i o t i t e , present i n most t h i n s e c t i o n s , has a ragged o u t l i n e , i s bent, and i s g e n e r a l l y l a r g e l y a l t e r e d to c h l o r i t e . The accessory m i n e r a l s , a p a t i t e and z i r c o n , occur as euhedral to subhedral c r y s t a l s u s u a l l y w i t h i n l a r g e r g r a i n s of rock-forming m i n e r a l s . Sphene may be e i t h e r euhedral, subhedral or occur as i r r e g u l a r aggreg-ates of anhedral g r a i n s c l o s e l y a s s o c i a t e d w i t h mafic or opaque m i n e r a l s . This a s s o c i a t i o n suggests that sphene (and leucoxene) i s an a l t e r a t i o n product of t i t a n i f e r o u s magnetite or i l m e n i t e . The opaque m i n e r a l s , which are predominantly magnetite, occur as minute anhedral aggregates of g r a i n s c l o s e l y a s s o c i a t e d w i t h mafic minerals (See Appendix I I -specimens 18 to 35 f o r petrographic d e s c r i p t i o n s of specimens and t h i n s e c t i o n s thought to be r e p r e s e n t a t i v e of the Hybrid phase). -36-Highland V a l l e y Phase D i s t r i b u t i o n . V a r i e t i e s and R e l a t i o n s to Other Phases The Highland V a l l e y phase forms a c o n c e n t r i c r i n g around the outer p a r t of the b a t h o l i t h enclosed by the Hybrid marginal phase. The High-land V a l l e y phase i s c o m p o s i t i o n a l l y and t e x t u r a l l y more uniform than the Hybrid phase, although i t s outer margin shows an increase i n amount of mafic minerals a t contacts w i t h the Hybrid phase and o l d e r s t r a t i f i e d r o c k s . In some places the Highland V a l l e y phase has g r a d a t i o n a l contacts w i t h the Hybrid phase, i n others i t seems to have a s s i m i l a t e d or mixed w i t h i t and i n s t i l l others i t c l e a r l y has intruded c r y s t a l l i n e Hybrid r o c k s . The Guichon v a r i e t y occurs c h i e f l y i n the northern p a r t of the' b a t h o l i t h but i s a l s o i n the south adjacent to contacts of Hybrid phase w i t h Chataway v a r i e t y . Chataway v a r i e t y occurs c h i e f l y , i n the southern p a r t of the b a t h o l i t h . Petrography Primary rock-forming minerals i n the Highland V a l l e y phase are p l a g i o c l a s e , o r t h o c l a s e , quartz, hornblende, b i o t i t e and minor a u g i t e . Accessory minerals i n c l u d e a p a t i t e , z i r c o n , sphene and opaque g r a i n s (magnetite, i l m e n i t e , c h a l c o p y r i t e , p y r i t e ) . Secondary m i n e r a l s , products of d e u t e r i c and hydrothermal a l t e r a t i o n and weathering i n c l u d e -37-e p i d o t e , s e r i c i t e , c h l o r i t e , p r e h n i t e , carbonate, leucoxene, z e o l i t e s , i r o n and manganese oxides and c l a y m i n e r a l s . Modes are l i s t e d i n Table I I , and shown i n Figure 7. Guichon V a r i e t y The Guichon v a r i e t y , mainly g r a n o d i o r i t e , i s r i c h e r i n mafic m i n e r a l s , p a r t i c u l a r l y b i o t i t e , than the Chataway v a r i e t y and shows the widest t e x t u r a l and compositional d i f f e r e n c e s . This v a r i e t y was f i r s t described and named by White, Thompson and McTaggart (White e t a l , 1957, p 276). The Guichon v a r i e t y , (Figure 8 ) , i s l i g h t grey to cream-grey u s u a l l y mottled by pink and i s evenly f l e c k e d by black to dark green-grey mafics. The rock i s medium to coarse-grained, hypidiomorphic granular w i t h p l a g i o c l a s e showing p r e f e r r e d o r i e n t a t i o n . Modes of the Guichon v a r i e t y f a l l mainly i n the g r a n o d i o r i t e p a r t of the ternary diagram, Figure 7b. Two f a l l i n the quartz d i o r i t e p a r t of the diagram. These two specimens were taken from the outer margin of the area u n d e r l a i n by Guichon v a r i e t y and probably show e f f e c t s of contamination by Hybrid phase and o l d e r s t r a t i f i e d r o c k s . Table I I shows ranges, f o r the s i x specimens of the g r a n o d i o r i t e composition, of 45.75% to 52.32% p l a g i o c l a s e , 8.24% to 16.03% o r t h o c l a s e , 17.55% to 20.68% quartz and 11.62% to 21.527., mafic m i n e r a l s . The two specimens of quartz d i o r i t e composition c o n t a i n 52.66% and 58.93% p l a g i o c l a s e , 0% to 2.71% o r t h o c l a s e , 11.70% and 16.32% quartz, and 24.56% and 26.38% mafic m i n e r a l s . -38-Feldspar comprises from 55% to 65% of the rock, of which up to 75%, of the t o t a l f e l d s p a r i s p l a g i o c l a s e . P l a g i o c l a s e i s euhedral to subhedral and shows p r e f e r r e d o r i e n t a t i o n i n most t h i n s e c t i o n s . Measured compositions show a range of An-^ to An^g. Orthoclase forms coarse i n t e r s t i t i a l masses p o i k i l i t i c a l l y e n c l o s i n g quartz, p l a g i o -c l a s e and mafic m i n e r a l s . Quartz i s anhedral, i n t e r s t i t i a l and commonly shows f r a c t u r e s and s t r a i n e d e x t i n c t i o n . Alignment of mafic minerals gives the rock a f o l i a t e d appearance. Dark m i n e r a l s , p a r t i c u l a r l y b i o t i t e , tend to form evenly d i s t r i b u t e d c l u s t e r s of g r a i n s . The amount of b i o t i t e and augite r e l a t i v e to horn-blende, as w e l l as t o t a l mafic content, increases towards contacts w i t h Hybrid phase. B i o t i t e i s g e n e r a l l y ragged i n o u t l i n e and g r a i n s are bent. Hornblende a l s o has an i r r e g u l a r anhedral o u t l i n e and i s commonly p o i k i l i t i c c o n t a i n i n g small anhedral remnant augite g r a i n s . Both b i o t i t e and hornblende g e n e r a l l y have a s l i g h t l y p o i k i l i t i c t e x t u r e e n c l o s i n g anhedral g r a i n s of quartz, f e l d s p a r and opaque g r a i n s . The opaque g r a i n s , l a r g e l y magnetite, commonly occur as anhedral g r a i n s or aggregates of gra i n s c l o s e l y a s s o c i a t e d w i t h mafic m i n e r a l s . Sphene may be euhedral or i n t e r s t i t i a l to p l a g i o c l a s e and g e n e r a l l y i s c l o s e l y a s s o c i a t e d w i t h opaque g r a i n s , suggesting presence of t i t a n i f e r -ous magnetite or i l m e n i t e . Other accessory m i n e r a l s , z i r c o n and a p a t i t e , are euhedral to subhedral and are in c l u d e d w i t h i n or between rock-forming g r a i n s . (For petrographic d e s c r i p t i o n s see Appendix I I , specimens 36 to 43). -39-Figure 8 Highland V a l l e y phase, Guichon v a r i e t y orthoclase stained yellow Figure 9 Highland Valley phase, Chataway v a r i e t y orthoclase stained yellow -40-Chataway Va r i e t y The Chataway v a r i e t y , mainly granodiorite, Figures 9 and 10, i s mottled light-cream-green, l i g h t grey and pink, i s medium- to coarse-grained with well separated evenly disseminated euhedral to subhedral mafic grains. A marked p o i k i l i t i c texture of hornblende i s character-i s t i c of t h i s v a r i e t y . ( V i s i b l e i n Figure 10). Figure 7c shows s i x of seven specimens f a l l i n g w ithin the grano--d i o r i t e f i e l d of the ternary diagram with one specimen of quartz d i o r i t e composition, probably the r e s u l t of contamination of nearby Hybrid phase. Table II shows plagioclase ranges i n amount from 48.327. to 63.497o and averages 54.34%. Orthoclase ranges from 4.897. to 21.98%, with an average of 10.937.. Quartz content has a range between 13.157o to 28.69%, with an average of 20.64%. Total mafic content ranges between 9.68% and 16.46% with an average of 11.957.. Hornblende i s commonly i n excess of b i o t i t e . Plagioclase i s subhedral to euhedral and shows preferred o r i e n t a -t i o n . I t commonly has normal zoning which ranges from An^i i n the core to An£2 at the margins. Orthoclase occur's as very coarse-grained p o i k i -l i t i c i n t e r s t i t i a l masses with uneven d i s t r i b u t i o n ; hence, the wide v a r i a t i o n i n orthoclase content from one t h i n section to another. Quartz i s i n t e r s t i t i a l to plagioclase and commonly shows strained e x t i n c t i o n . Mafic minerals have d i s t i n c t o u t l i n e s and are evenly d i s t r i b u t e d throughout the matrix. Hornblende p o i k i l i t i c a l l y encloses quartz, p l a g i o c l a s e , b i o t i t e and opaque grains. Many hornblende grains have corroded margins caused by p a r t i a l replacement by quartz and orthoclase. Figure 11 LeRoy " g r a n o d i o r i t e " -42-B i o t i t e grains are commonly bent. Opaque minerals are int imate ly associated with mafic minerals . (For petrographic descr ipt ions see Appendix I I , specimens 44 to 49 i n c l u s i v e ) . LeRoy "Granodior i te" D i s t r i b u t i o n and Relations to Other Phases The LeRoy "granodior i te" occurs in Chataway (and Witches Brook?) i n i r regu lar masses and dyke - l ike bodies which range i n thickness from a few feet to a few hundred fee t . Accurate estimate of thickness of most LeRoy "granodior i te" bodies i s not possible because of l imi ted outcrops. I ts occurrence i s not confined to any wel l -def ined area. On Figure 6 the area shown as LeRoy i s mainly under la in , i t i s be l ieved, by Chataway v a r i e t y . Petrography The LeRoy "granodior i te" resembles the Chataway var ie ty i n texture and composition but i s more f ine -g ra ined . I t can be confused e a s i l y wi th Witches Brook phase. Primary rock-forming minerals , accessory and secondary minerals are the same as for uncontaminated Highland Va l ley phase. LeRoy "granodior i te" i s l i g h t cream-grey with some pink mot t l ing . Mafic minerals are evenly d i s t r i b u t e d , have p o i k i l i t i c textures and have d i s t i n c t c r y s t a l margins. -43-Modes of LeRoy " g r a n o d i o r i t e " , l i k e Chataway v a r i e t y , a l s o f a l l l a r g e l y w i t h i n the g r a n o d i o r i t e p a r t of the ternary diagram, (Figure 7d), w i t h only one of s i x specimens of quartz d i o r i t e composition. Feldspar comprises 60% to 66% of the rock of which 4% to 31% of the t o t a l f e l d s -par i s o r t h o c l a s e . Table IT shows t h a t p l a g i o c l a s e content ranges from 42.91% to 58.64% and averages 50.72%. Orthoclase has a range of 2.48% to 19.37% w i t h an average of 12.107o. The apparent v a r i a t i o n i n ortho-c l a s e content may be l a r g e l y the r e s u l t of sampling e r r o r . Quartz content ranges from 17.75% to 28.01% and averages 24.67%. T o t a l mafic content ranges between 8.057. and 14.207, .with an average value of 10.577o. The amount of hornblende i s approximately equal to the amount of b i o t i t e i n most specimens, although i n some hornblende i s dominant. P l a g i o c l a s e i s subhedral, has a p r e f e r r e d o r i e n t a t i o n and shows normal zoning. Measurement of p l a g i o c l a s e composition using the a l b i t e twin method gives a range from An37 to A n ^ . Orthoclase occurs as large i n t e r s t i t i a l anhedral g r a i n s s e v e r a l m i l l i m e t e r s i n s i z e . I t p o i k i l i t i c -a l l y encloses p l a g i o c l a s e and i s s l i g h t l y p e r t h i t i c . Quartz i s i n t e r -s t i t i a l wedge-shaped, p o i k i l i t i c a l l y encloses p l a g i o c l a s e and has s t r a i n e d e x t i n c t i o n . . . > A c h a r a c t e r i s t i c of t h i s u n i t i s that mafic minerals are evenly disseminated, have p o i k i l i t i c textures and d i s t i n c t c r y s t a l margins. ( P e t r o g r a p h i c d e s c r i p t i o n s are l i s t e d i n Appendix I I , specimens 50 to 53 i n c l u s i v e ) . -44-Modol Analyses 1 0 0 % Ouarti 1 0 0 % Quart* Orthoclose , Plagioclase Orthoclase Plagioclase (o) Gump Lake Phase : (b) Bethlehem Phase • Thin-sect ion o Stained slab X Average Composition 1 0 0 % 1 0 0 % 1 0 0 % 1 0 0 % Orthoclase _ Plagioclase Orthoclase Plagioclase (c) Witches Brook Phase (d) Bethsaida Phase Figure 12  -45-Gump Lake Phase D i s t r i b u t i o n and F i e l d R e l a t i o n s The Gump Lake phase covers an area of 9 square mile s east of Gump Lake. T e x t u r a l l y and c o m p o s i t i o n a l l y the Gump Lake phase c l o s e l y r e -sembles the youngest c e n t r a l Bethsaida phase of the b a t h o l i t h . I t i s coarse-grained, somewhat p o r p h y r i t i c , g r a n o d i o r i t e or quartz monzonite, has low mafic content and has o s c i l l a t o r y zoning of p l a g i o c l a s e s i m i l a r to t hat of the Bethlehem phase. I t i s cut by the Witches Brook phase of intermediate to young age which a l s o cuts the Highland V a l l e y phase. The Gump Lake phase i s considered, on the scanty evidence a v a i l a b l e , to be of intermediate age, p o s s i b l y between Highland V a l l e y and Bethlehem phase i n age. Petrography Rocks of the Gump Lake phase (Figure 13) are mottled pink and l i g h t cream-grey and are medium to coarse-grained w i t h s e r i a t e to p o r p h y r i t i c t e x t u r e . Figure 12a shows modes f o r the Gump Lake phase determined from t h i n s e c t i o n s f a l l i n the g r a n o d i o r i t e p a r t of the ternary diagram and modes determined from s t a i n e d slabs f a l l i n the quartz monzonite p a r t of the diagram. The discrepancy i s probably the r e s u l t of sampling e r r o r . Be--46-Figure 14 Witches Brook phase c u t t i n g Hybrid phase. East side of Guichon Creek B a t h o l i t h -47-cause of'the very coarse-grained s e r i a t e to p o r p h y r i t i c texture and un-even d i s t r i b u t i o n of or t h o c l a s e the modes f o r o r t h o c l a s e , quartz and p l a g i o c l a s e determined us i n g s t a i n e d slabs are considered more r e l i a b l e than values obtained from the r e l a t i v e l y small area of t h i n s e c t i o n s . E x c e l l e n t mineral d e f i n i t i o n was obtained i n c o l o r s l i d e s of s t a i n e d s l a b s (Figure 13). Modes of sta i n e d slabs (Table IV) show values of 36% to 40% p l a g i o c l a s e , 25% to 33% o r t h o c l a s e , and 22% to 28% qu a r t z . Table I I shows three t h i n s e c t i o n s of Gump Lake phase have a range of 36.977«, to 49.45% p l a g i o c l a s e , 11.02% to 16.08% o r t h o c l a s e , 29.11% to 38.87% quartz and 5.307. to 7.627> t o t a l mafic minerals w i t h b i o t i t e dominant over hornblende. P l a g i o c l a s e (An35) shows p o o r l y developed o s c i l l a t o r y zoning and has a l b i t i z e d margins of g r a i n s i n which there i s a p o o r l y developed granophyric t e x t u r e . P a r t s of some p l a g i o c l a s e g r a i n s are i n t e n s e l y s e r i c i t i z e d . Orthoclase i s anhedral, i n t e r s t i t i a l , p e r t h i t i c , and p o i k i -l i t i c a l l y encloses small anhedral p l a g i o c l a s e g r a i n s . Quartz forms conspicuous anhedral i n t e r s t i t i a l very coarse g r a i n s or aggregates of smaller g r a i n s . A few g r a i n s show f r a c t u r e s and s t r a i n e d e x t i n c t i o n . The mafic minerals are anhedral and have weak p o i k i l i t i c t e x t u r e s , e n c l o s i n g p l a g i o c l a s e and quartz. B i o t i t e i s commonly more abundant than hornblende. (For petrographic d e s c r i p t i o n s see Appendix I I , s p e c i -mens 55 and 56). -48-Bethlehem Phase D i s t r i b u t i o n and F i e l d R e l a t i o n s Bethlehem phase g r a n o d i o r i t e , almost completely e n c i r c l i n g a c e n t r a l core of the Guichon b a t h o l i t h , was f i r s t d escribed and named, a f t e r i t s type l o c a l i t y on the Bethlehem Copper property, by White, Thompson and McTaggart (White, e t a l , 1957, p 277). In common w i t h other phases, the Bethlehem phase has minor v a r i a t i o n s . A seven-foot x e n o l i t h of Guichon v a r i e t y i n the Bethlehem phase occurs on the Bethlehem property and, a l -though no c h i l l e d contacts are i n evidence, c l e a r l y shows that the B e t h l e -hem phase i s the younger. Petrography The mineralogy of the Bethlehem phase i s s i m i l a r to that of other phases, although augite i s not commonly present. The rock-forming minerals i n c l u d e p l a g i o c l a s e , o r t h o c l a s e , quartz, b i o t i t e and hornblende w i t h accessory m i n e r a l s , sphene, z i r c o n , ( r u t i l e ) , a p a t i t e and opaque g r a i n s . A l t e r a t i o n products i n c l u d e epidote, c h l o r i t e , t r e m o l i t e , ( a c t i n o l i t e ) , tourmaline, z e o l i t e s , and p r e h n i t e . Bethlehem phase has a s l i g h t l y p o r p h y r i t i c texture which i s more conspicuous near the inner c o n t a c t w i t h Bethsaida phase. Modes l i s t e d i n Table I I show that the Bethlehem phase i s composed -50-of 53.76% to 63.47% p l a g i o c l a s e , 5.98% to 15.51% o r t h o c l a s e , 18.26% to .25.06% quartz and 4.64% to 10.95% mafic minerals of which e i t h e r horn-blende or b i o t i t e may be dominant. P l a g i o c l a s e e x h i b i t s o s c i l l a t o r y zoning w i t h composition of centers of g r a i n s ranging between A ^ g and An^j but most t h i n s e c t i o n s i n d i c a t e a smaller v a r i a t i o n of between An35 and An39. P r e f e r r e d o r i e n t a t i o n of p l a g i o c l a s e i s common. Orthoclase i s i n t e r s t i t i a l , p o i k i l i t i c , p e r t h i t i c , and forms large patches an i n c h or two i n diameter. Quartz i s anhedral, i n t e r s t i t i a l and shows s t r a i n e d e x t i n c t i o n . B i o t i t e c r y s t a l s are commonly bent. Hornblende has a conspicuous p o i k i l i t i c texture and i r r e g u l a r d i s t r i b u t i o n ; both are c h a r a c t e r i s t i c s of t h i s phase (Figures 15 and 16). (For sample d e s c r i p t i o n s see Appendix I I , specimens 57 to 61). Witches Brook Phase D i s t r i b u t i o n . V a r i e t i e s and F i e l d R e l a t i o n s The c o n c e n t r i c arrangement of major i n t r u s i v e phases i s i n t e r r u p t e d by v a r i e t i e s of the Witches Brook phase. There i s no w e l l defined mass of Witches Brook phase as there i s f o r most other phases and i t s o c c u r r -ences and v a r i e t i e s cannot adequately be shown on a map of s c a l e 1 i n c h to 1 m i l e . I r r e g u l a r masses and d y k e - l i k e bodies of Witches Brook c u t •Guichon and Chataway. v a r i e t i e s and Hybrid and Gump Lake phases. I t a l s o -51-occurs as a matrix of b r e c c i a f i l l i n g i n t e r s t i c e s between angular f r a g -ments of the ol d e r phases. Although Witches Brook phase can be seen i n ol d e r phases almost everywhere i n the b a t h o l i t h , o n ly areas where i t i s most abundant are o u t l i n e d on Figure 6. A body of quartz monzonite, l o c a l l y c a l l e d Bethlehem Granite on the property of Bethlehem Copper. Corporation, i n t r u d e s Bethlehem phase, resembles Witches Brook and i s t e n t a t i v e l y c o r r e l a t e d w i t h that phase. A s i m i l a r quartz monzonite, on the west margin of the b a t h o l i t h near S p a t s u m i s a l s o c o r r e l a t e d w i t h the Witches Brook phase. The Witches Brook phase shows more t e x t u r a l and compositional v a r i a -t i o n s than any phase other than the Hybrid phase. Where the phase forms la r g e bodies the rock i s s i m i l a r i n texture to Bethlehem phase. Where Witches Brook occurs as smaller bodies i t i s not a b l y more f i n e - g r a i n e d and r i c h e r i n quartz and o r t h o c l a s e . As there apparently i s a complete grada-t i o n i n t e x t u r e , g r a i n s i z e and composition, they cannot e a s i l y be separ-ated i n t o u n i t s . For ease of d e s c r i p t i o n , three v a r i e t i e s are d i s t i n g u i s h e d A, B, and C. Petrography Mineralogy of the Witches Brook phase i s s i m i l a r to that of Bethlehem phase. Rock-forming minerals inclu d e p l a g i o c l a s e , o r t h o c l a s e , q u a r t z , b i o t i t e , hornblende, and minor a u g i t e . Accessory minerals i n -clude a p a t i t e , sphene, opaque g r a i n s ( l a r g e l y magnetite w i t h very sparse -52-c h a l c o p y r i t e , b o r n i t e and p y r i t e ) . A l t e r a t i o n products are c h l o r i t e , e p i d o t e , s e r i c i t e , p rehnite and z e o l i t e s . Modes p l o t t e d on the ternary diagram, (Figure 12c), and l i s t e d i n Table I I , show a range of 28.087. to 52.117. p l a g i o c l a s e , 10.447. to 29.42% o r t h o c l a s e , 25.50% to 43.19% quartz and 1.90% to 10.91% mafic minerals w i t h b i o t i t e commonly dominant over hornblende. M a f i c content i s low, i n the order of 2%,, f o r Spatsum quartz monzonite and Bethlehem " g r a n i t e " , w h i le i n other areas i t i s 9% to 11% w i t h an average of s l i g h t l y more than 9%. In view of the g e n e r a l l y f i n e g r a i n s i z e and homogeneity of the rock w i t h i n l i m i t e d areas, the v a r i a t i o n shown on Figure 12c i s considered to be a true one probably i l l u s t r a t i n g d i f f e r -e n t i a t i o n w i t h i n the phase. Witches Brook V a r i e t y "A" Witches Brook v a r i e t y "A" g r a n o d i o r i t e (Figure 18) i s l i g h t to medium grey, u s u a l l y s l i g h t l y mottled by pink, medium to coarse-grained and weakly p o r p h y r i t i c i n t e x t u r e . The rock i s 607. f e l d s p a r , of which 70% to 80% of the t o t a l f e l d s p a r i s p l a g i o c l a s e ( A n 3 8 ) . Mafic content i s about 107. w i t h hornblende u s u a l l y , s l i g h t l y more abundant than b i o t i t e . Commonly, traces of augite are v i s i b l e . The mafic minerals c h a r a c t e r i s t i c a l l y occur as aggregates of very f i n e to coarse g r a i n s r e s u l t i n g i n small dark c l o t s w i t h i n d i s t i n c t o u t l i n e . In a d d i t i o n , v a r i e t i e s "A" and "B" have randomly disseminated coarse-grained p o i k i l i t i c hornblende c r y s t a l s . In t h i n s e c t i o n the p l a g i o c l a s e -53-•Figure 18 Witches Brook phase, V a r i e t y "A" or t h o c l a s e s t a i n e d y e l l o w -54-(An-jg) shows normal zoning w i t h some weak o s c i l l a t o r y zoning and weakly developed p r e f e r r e d o r i e n t a t i o n . This v a r i e t y of Witches Brook phase c l o s e l y resembles Bethlehem phase and, indeed, may be a v a r i e t y of that phase. (For petrographic d e s c r i p t i o n see Appendix I I , specimen 62). Witches Brook V a r i e t y "B" V a r i e t y "B" (Figure 19) i s s i m i l a r to v a r i e t y "A" but i s more f i n e -grained and somewhat r i c h e r i n ort h o c l a s e and quart z . T e x t u r a l l y . the two v a r i e t i e s have the same c h a r a c t e r i s t i c s . V a r i e t y "B" may be l i g h t to medium grey or medium to dark grey i n c o l o r , u s u a l l y mottled s l i g h t l y w i t h pink. The rock i s composed of from 557. to 657. f e l d s p a r of which 657o to 857o i s p l a g i o c l a s e (An-j^ to An-jg). Some p l a g i o c l a s e g r a i n s have a . l b i t i z e d rims and a granophyric t e x t u r e . Orthoclase i s i n t e r s t i t i a l , p o i k i l i t i c . Quartz i s i n t e r s t i t i a l , c onspic-uous, anhedral and comprises about 257. of the rock. The rock contains 107. mafic minerals w i t h about equal p r o p o r t i o n s of b i o t i t e and hornblende and a l i t t l e a u g i t e . The mafic m i n e r a l s c h a r a c t e r i s t i c a l l y form aggregates of small g r a i n s showing i n d i s t i n c t o u t l i n e s w i t h some unevenly disseminated more coarse-grained p o i k i l i t i c hornblende. (For petrographic d e s c r i p t i o n s see Appendix I I , specimens 63 to 68). Witches Brook V a r i e t y "C" V a r i e t y "C" (Figure 20), i s s i m i l a r to "B", has a more f i n e - g r a i n e d m a t r i x and i s u s u a l l y more d i s t i n c t l y p o r p h y r i t i c as a r e s u l t of abundantly Figure 20 Witches Brook phase, V a r i e t y "C", ort h o c l a s e s t a i n e d y e l l o w -56-disseminated medium to coarse g r a i n s of p l a g i o c l a s e . The rock i s pink mottled by l i g h t grey. V a r i e t y "C" i s r i c h e r i n o r t h o c l a s e and quartz than v a r i e t i e s "A" ? and "B". Feldspar comprises about 50% to 65% of the rock, of which 50% to 60% of the t o t a l f e l d s p a r i s p l a g i o c l a s e (An4o)» Orthoclase i s i n t e r -s t i t i a l , p o i k i l i t i c a l l y e n c l o s i n g p l a g i o c l a s e , quartz and mafic m i n e r a l s . Quartz, ranging from 25% to 40%, i s anhedral and i n t e r s t i t i a l to p l a g i o -c l a s e . M a f i c minerals range from 2% to 10% w i t h b i o t i t e predominating over hornblende. The dark minerals form aggregates of. f i n e g r a i n s . (For petrographic d e s c r i p t i o n s see Appendix I I , specimens 69 to 72). Bethsaida Phase D i s t r i b u t i o n and F i e l d R e l a t i o n s The Bethsaida phase (Figure 21) forms a c e n t r a l core of the Guichon Creek b a t h o l i t h that i s approximately 13 m i l e s long and 4% m i l e s wide. A dyke thought to be Bethsaida, c h i l l e d a g a i n s t Guichon v a r i e t y , appears on the n o r t h side of Highland V a l l e y on the Bethlehem Copper property and i s l o c a l l y c a l l e d the "Spud Lake Porphyry". A . v a r i e t y of Bethsaida g r a n o d i o r i t e - quartz monzonite (Figure 22) appears to be c h i l l e d a g a i n s t Bethlehem g r a n o d i o r i t e on the south peak of Gnawed Mountain. This i s the only major contact showing c h i l l i n g that was seen i n the area of the -Guichon b a t h o l i t h . Figure 22 Bethsaida phase, Gnawed Mountain v a r i e t y , o r t h o c l a s e s t a i n e d y e l l o w -58-Petrography c Bethsaida g r a n o d i o r i t e - quartz monzonite forms d i s t i n c t i v e out-crops w i t h rough weathered su r f a c e s . P r e f e r e n t i a l weathering of m i n e r a l s leaves quartz standing i n r e l i e f . Table I I shows p l a g i o c l a s e ranges from 37.62% to 62.16%, ortho-c l a s e from 5.28% to 14.55%, quartz from 16.38% to 45.71% and mafic minerals from 2.89% to 12.24% w i t h b i o t i t e dominant over hornblende. Because of * the coarse-grained p o r p h y r i t i c nature of the rock, much of the v a r i a t i o n i n quartz content could be the r e s u l t of sampling e r r o r as i t occurs as coarse, subhedral, unevenly disseminated phenocrysts (Figures 21 and 22). P l a g i o c l a s e (An3^ to An^g) i s euhedral and has o s c i l l a t o r y zoning. Some quartz g r a i n s are subhedral or i n t e r s t i t i a l to p l a g i o c l a s e but they a l s o form l a r g e , c l e a r phenocrysts which are a conspicuous feature of t h i s phase. Orthoclase i s i n t e r s t i t i a l to p l a g i o c l a s e , quartz and mafic m i n e r a l s , and i s p e r t h i t i c . B i o t i t e occurs as very coarse-grained euhedral b o o k - l i k e phenocrysts which are another c h a r a c t e r i s t i c of t h i s phase. Where there i s an i n -crease i n the amount of p o i k i l i t i c hornblende the rock type i s d i f f i c u l t to d i s t i n g u i s h from coarse-grained, p o r p h y r i t i c Bethlehem phase near the Bethlehem-Bethsaida c o n t a c t . (For petrographic d e s c r i p t i o n s of Bethsaida, see Appendix I I , specimens 73 and 74). -59-Late Phases Bethlehem Porphyries Porphyry dykes of v a r i o u s textures and compositions, b e l i e v e d to be g e n e t i c a l l y r e l a t e d to the younger phases of the b a t h o l i t h , occur i n a n o r t h e r l y trending swarm c r o s s i n g Highland V a l l e y and west of Bethlehem Copper-Corporation property. The swarm i s a t l e a s t . 1 0 m i l e s l o n g and 3 to 5 m i l e s wide becoming narrower at the n o r t h end. These dykes have been described by White, Thompson and McTaggart and subseq-u e n t l y by Carr (White, e t a l , 1957, p 278; Carr, 1960, pp 71-73). S i m i l a r p o rphyries have been noted i n other places i n the area of the b a t h o l i t h as s i n g l e dykes or groups of two or three dykes but the Highland V a l l e y swarm i s by f a r the most notable occurrence. White, e t a l , 1957, p 228, d i s t i n g u i s h two types of dykes on the Bethlehem Copper property which, though of s i m i l a r composition, d i f f e r markedly i n t e x t u r e . The two groups are d a c i t e porphyry and quartz d i o r i t e porphyry (White, e t a l , 1957, p 228). On the b a s i s of s u b t l e d i f f e r e n c e s i n texture and mineralogy, presence or absence of quartz phenocrysts, Carr f u r t h e r subdivided the porphyries (Carr, 1959, unpublished). Gnawed Mountain Porphyries The Gnawed Mountain porphyries are thought to represent the youngest phase of the b a t h o l i t h . These occur as small i r r e g u l a r bodies and dykes w i t h c h i l l e d margins i n Bethsaida and to a l e s s e r extent i n Bethlehem .and older phases. One such body forms a small b r e c c i a pipe on the west -60-f l a n k of Gnawed Mountain, another forms a large n o r t h e r l y trending dyke on the east shoulder of Gnawed Mountain. Others are r e p o r t e d to occur on the Lornex property (Carr, personal communication). Gnawed Mountain porphyries c o n s i s t of 25% to 35%, coarse-grained euhedral to subhedral p l a g i o c l a s e and w i t h very coarse-grained quartz c r y s t a l s set i n a f i n e - g r a i n e d quartz and f e l d s p a r - r i c h m a t r i x . Where c h i l l e d , the groundmass i s very f i n e - g r a i n e d to c r y p t o c r y s t a l l i n e . These rocks are s i m i l a r i n appearance and are probably c l o s e l y r e l a t e d to the Gnawed Mountain v a r i e t y of Bethsaida (Figure 22). L e u c o c r a t i c Rocks .Leucocratic dykes and small i r r e g u l a r l e u c o c r a t i c masses can be seen a t almost any place i n the area of the b a t h o l i t h but are most abund-ant near contacts of younger phases and w i t h i n the Bethsaida phase. A l e u c o c r a t i c body of unknown extent was crossed about.two mile s west of Gump Lake i n the Witches Brook, LeRoy, Chataway, Guichon complex. ' One outcrop area comprised e n t i r e l y , of l e u c o c r a t i c rock, i s a t l e a s t 150 f e e t i n longest diameter, i s f i n e to medium-grained, equigranular and weathers p i n k i s h white. The l e u c o c r a t i c bodies and dykes are v a r i a b l e i n g r a i n - s i z e rang-i n g from a p l i t e to pegmatite and are composed p r i n c i p a l l y of quartz, o r t h o c l a s e and p l a g i o c l a s e . Small amounts of copper m i n e r a l i z a t i o n ( c h a l p y r i t e and b o r n i t e ) are commonly a s s o c i a t e d w i t h these bodies. -61-B r e c c i a s W i t h i n the B a t h o l i t h Three main types of b r e c c i a occur w i t h i n the b a t h o l i t h : f a u l t b r e c c i a , i n t r u s i o n b r e c c i a and "p i p e " b r e c c i a . F a u l t ' b r e c c i a s form complicated branching and braided s t r u c t u r e s of sheared, s l i c k e n s i d e d , comminuted, a l t e r e d rock and gouge ranging from a few f e e t to hundreds of f e e t i n width. Hydrothermal a l t e r a t i o n and m i n e r a l i z a t i o n are p a r t i -c u l a r l y p r e v a l e n t i n f a u l t b r e c c i a s which p o s s i b l y served as channelways f o r hydrothermal f l u i d s . I n t r u s i o n b r e c c i a s are common at i n t r u s i v e contacts between Hybrid, Guichon and Witches Brook phases. Angular fragments of the older phases are healed by a m a t r i x of the younger phase. "P i p e s " of b r e c c i a , c l o s e l y a s s o c i a t e d w i t h p o r p h y r i e s , i n t r u d e Highland V a l l e y , Bethlehem, and Bethsaida phases and occur on the Bethle-hem Copper, Trojan, K r a i n , Salmo P r i n c e and Gnawed Mountain p r o p e r t i e s . They range i n s i z e from a few f e e t to 2000 f e e t i n longest dimension, and are commonly elongate but may be n e a r l y equidimensional i n p l a n . D r i l l core data from Bethlehem and Trojan p r o p e r t i e s suggest they are p i p e - l i k e i n shape tape r i n g downwards (White, e t a l , 1957, p 278). Most b r e c c i a " p i p e s " are c l o s e l y a s s o c i a t e d w i t h l a t e porphyries and younger phases a t contacts w i t h older phases. Most fragments are angular, few are rounded; most are' l e s s than 2 inches across but blocks s e v e r a l f e e t i n diameter are common. The matrix i s composed of comminuted rock m a t e r i a l , l a r g e l y broken g r a i n s of f e l d s p a r , quartz and small rock fragments which are commonly impregnated and p a r t l y r e p l a c e d by b i o t i t e , tourmaline, -62-q u a r t z , c h a l c o p y r i t e , b o r n i t e and hematite. Although b r e c c i a " p i p e s " of the area are s i m i l a r i n gross appear-ance they d i f f e r i n d e t a i l . Contacts between b r e c c i a may be sharp w i t h r e l a t i v e l y sound m a t e r i a l , as i n the Iona B r e c c i a on the Bethlehem Copper Corporation property, or g r a d a t i o n a l showing increase i n s i z e of fragments towards the margins where fragments are only s l i g h t l y d i s -p l a c e d as a t Gnawed Mountain. Some "p i p e " b r e c c i a s show grad a t i o n i n s i z e of fragments; others show predominantly two d i s t i n c t :sizes of angu-l a r fragments i n a sandstone-sized m a t r i x . B r e c c i a fragments may be touching or may be w e l l separated. The dominant n o n - m e t a l l i c minerals r e p l a c i n g f i n e l y comminuted i n t e r s t i t i a l m a t r i x vary from one "p i p e " of b r e c c i a to another. Fine-grained b i o t i t e w i t h only minor amounts of tourmaline r e p l a c e s much of the ma t r i x of the Iona B r e c c i a . Tourmaline i s the dominant n o n - m e t a l l i c mineral r e p l a c i n g the m a t r i x of b r e c c i a a t Trojan and some b r e c c i a s a t Gnawed Mountain. At the Salmo P r i n c e property, the b r e c c i a m a t r i x i s l a r g e l y comminuted rock fragments hydrothermally a l t e r e d to epidote w i t h some c a l c i t e . Other small "pipes'.* of b r e c c i a a t Gnawed Mountain have a matrix composed l a r g e l y of quartz and f e l d s p a r . Some "p i p e s " of b r e c c i a c o n t a i n economic copper m i n e r a l i z a t i o n , others c o n t a i n hematite and s t i l l others are unmineralized by m e t a l l i c m i n e r a l s . Suggested modes of o r i g i n of " p i p e s " of b r e c c i a are surface b r e c c i a t i o n , f a u l t i n g , s o l u t i o n c o l l a p s e , shrinkage accompanying meta-somatism, c o l l a p s e consequent on r e l e a s e of magmatic pressure and ex-p l o s i o n i n the lower p a r t of a v o l c a n i c s t r u c t u r e . -63-P h y s i c a l c h a r a c t e r i s t i c s and composition of "p i p e s " of b r e c c i a o c c u r r i n g w i t h i n the b a t h o l i t h e l i m i n a t e most of the suggested modes of o r i g i n (White, e t a l , 1957, p 279). The b r e c c i a s are g e n e r a l l y of a c r o s s - c u t t i n g nature, are composed of only p l u t o n i c rock, so are not formed on the surface by sedimentary or v o l c a n i c processes. O r i g i n by f a u l t i n g i s precluded on the b a s i s of absence of r e l a t e d major f a u l t s i n most b r e c c i a s , n e a r l y equidimensional o u t l i n e of many, l o c a l abundance of f i n e m a t r i x and absence of fragments showing s l i c k e n s i d e s . Collapse by s o l u t i o n , shrinkage during a l t e r a t i o n and withdrawal of supporting magma are not favoured as mechanisms f o r producing " p i p e s " of b r e c c i a be-cause of the abundance of small fragments i n l o c a l areas, abundance of extremely comminuted f i n e - g r a i n e d m a t r i x , general low grade of a l t e r a t i o n and because of the presence of small ( f r a c t i o n of an inch) c a v i t i e s , many of which are p o s t - b r e c c i a . The favoured mode of o r i g i n i n v o l v e s subvolcanic e x p l o s i o n s . These • take place when the pressure of v o l a t i l e s exceeds the c o n f i n i n g s t r e n g t h i n cupolas. The increase i n pressure of v o l a t i l e s may have been brought about by upward and outward d i f f u s i o n of v o l a t i l e s i n order to e q u a l i z e v o l a t i l e vapour pressure throughout the magma (Kennedy, 1955, pp 489-502). Separation of anhydrous phases by continued c o o l i n g would increase vapour pressure of v o l a t i l e s (Kennedy, 1955, p 498). Carr suggests a s i m i l a r o r i g i n . Porphyry-forming magma s p l i t i n t o numerous connected dykes i n c o l d f r a c t u r e d rock a t r e l a t i v e l y shallow depths. C h i l l i n g and r a p i d c r y s t a l l i z a t i o n caused a d r a s t i c increase i n vapour pressure which ex--64-ceeded the c o n f i n i n g pressure, caused an e x p l o s i o n , which r e s u l t e d i n development of b r e c c i a (Carr, 1960, p 73). DEUTERIC AND HYDROTHERMAL ALTERATION An i n t e n s i v e study of rock a l t e r a t i o n was not attempted as p a r t of t h i s t h e s i s but some general comments can be made. White, e t a l , (1957) discussed d e u t e r i c and hydrothermal a l t e r a t i o n of the rock on Bethlehem Copper Corporation property. Widespread d e u t e r i c a l t e r a t i o n which probably occurred during a l a t e magmatic stage, was followed by more l o c a l i z e d hydrothermal a l t e r a t i o n . The f i n d i n g s of White, e t a l , g e n e r a l l y hold true throughout the b a t h o l i t h . D e u t e r i c a l t e r a t i o n i s p r i m a r i l y p r o p y l i t i c and s a u s s u r i t i c and has a f f e c t e d to a v a r y i n g degree o l d e r rocks a t the b a t h o l i t h margin and a l l i n t r u s i v e phases. In many rocks that have been d e u t e r i c a l l y a l t e r e d , o r t h o c l a s e and to a l e s s e r extent p l a g i o c l a s e , have acquired a r e d d i s h c o l o r a t i o n . B i o t i t e and hornblende are c h l o r i t i z e d and e p i d o t i z e d . Replacement of hornblende by pale to c o l o r l e s s a c t i n o l i t e occurs l o c a l l y as noted by White, et a l , on the Bethlehem Copper Corporation property. Such a l t e r a t i o n i s a l s o common i n the Hybrid phase a t the b a t h o l i t h margin. Hydrothermal minerals a s s o c i a t e d w i t h copper sulphide ore d e p o s i t s of Bethlehem Copper Corporation i n c l u d e : epldote, t r e m o l i t e , tourmaline, r u t i l e , quartz, b i o t i t e , a l b i t e , p r e h n i t e , c a l c i t e , muscovite, c l a y m i n e r a l s ( m o n t m o r i l l o n i t e , p o s s i b l y k a o l i n i t e , i l l i t e and a l u n i t e ) , -65-z e o l i t e s ( l e o n h a r d i t e , heulandite, s t i l b i t e , c h a b a z i t e ) , and c h l o r i t e (White, e t a l , 1957, p 281). To t h i s l i s t should be added o r t h o c l a s e . which-occurs i n other deposits of the area. The r e l a t i v e abundance of these a l t e r a t i o n minerals v a r i e s from place to place i n the b a t h o l i t h . For example, tourmaline i s common, although not abundant, i n the Iona B r e c c i a at the Bethlehem property; whereas, at the Trojan property two m i l e s to the northwest, and at Gnawed Mountain three m i l e s to the south, i t i s a major c o n s t i t u e n t of b r e c c i a s . Secondary quartz i s r e l a t i v e l y scarce on the Bethlehem property but i s more abundant on Lornex property f i v e m i l e s southwest of Bethlehem property. Secondary b i o t i t e composes a l a r g e p a r t of the m a t r i x of Iona B r e c c i a but was not observed i n q u a n t i t y elsewhere on the b a t h o l i t h . Muscovite i s commonly developed i n vein-type d e p o s i t s , p a r t i c u l a r l y i n those of O.K., Empire, Skeena and Snowstorm p r o p e r t i e s (White, et a l , 1957, p 280). C h l o r i t e , e pidote, tourmaline, and to a l e s s e r extent potassium f e l d s p a r , are widespread throughout the b a t h o l i t h i n j o i n t s or other f r a c t u r e s , • commonly accompanied by t r a c e s of copper s u l p h i d e s . SPECIFIC GRAVITIES OF PHASES The s p e c i f i c g r a v i t y . o f most rock specimens was measured using a s p e c i f i c g r a v i t y balance patterned a f t e r the design obtained from P r o f -essor J.D. Barksdale, Department, of Geology, U n i v e r s i t y of Washington. -66-The o r i g i n a l idea was found by Barksdale i n Brush and P e n f i e l d , 1898 (1911, 16th Ed., p 235). The balance used i n the present study was b u i l t by J . Parry who f i r s t used i t to t e s t the f e a s i b i l i t y of d i s t i n g -u i s h i n g between v a r i o u s phases of the Guichon b a t h o l i t h by means of s p e c i f i c g r a v i t y ( P a r r y , 1964). Because Parry's p r e l i m i n a r y r e s u l t s were encouraging, s p e c i f i c g r a v i t i e s were measured f o r more than 850 specimens of the v a r i o u s phases of the b a t h o l i t h . The s p e c i f i c g r a v i t y data were punched on computer cards and programmed f o r computation of means and standard d e v i a t i o n s by Dr. A.J. S i n c l a i r of the U n i v e r s i t y of B r i t i s h Columbia. The r e s u l t s are l i s t e d on Table IV and "best f i t " , curves based on standard d e v i a t i o n were drawn. The curves provide a means of comparing phases and v a r i e t i e s (Figure 23). The broader curves have a greater standard d e v i a t i o n and wider range of measured s p e c i f i c g r a v i t i e s . The narrower curves have a smaller standard d e v i a t i o n and i n d i c a t e a smaller range of measured v a l u e . S p e c i f i c g r a v i t y , w i t h the e x c e p t i o n of Gump Lake phase, decreases p r o g r e s s i v e l y from outer marg-i n a l phases w i t h an average s p e c i f i c g r a v i t y of .2.80 to the i n n e r , younger Bethsaida w i t h an average of 2.64. S p e c i f i c g r a v i t i e s of Bethlehem phase and Witches Brook phase are almost i d e n t i c a l . The decrease i n s p e c i f i c g r a v i t y w i t h decreasing age of phase i s thought to be l a r g e l y the r e s u l t of a decrease i n amount of mafic m i n e r a l s and to a l e s s e r extent, a decrease i n amount of magnetite i n younger phases. A r e l a t i v e l y ' l a r g e amount of o r t h o c l a s e and quartz, although not showing a c o n s i s t e n t increase w i t h decreasing age, c o r i t r i b --67-TABLE V: Mean Values and Standard D e v i a t i o n s of S p e c i f i c G r a v i t i e s Phase or V a r i e t y Hybrid Guichon Chataway LeRoy Gump Lake Bethlehem Witches Brook Bethsaida Number of Specimens 185 177 127 59 13 61 173 74 Mean S p e c i f i c G r a v i t y 2.7977 2.7423 2.6957 2.6876 2.6500 2.6746 2.6744 2.6436 Standard D e v i a t i o n 0.0848 0.0427 0.0349 0.0202 0.0286 0.0248 0.0325 0.0182 Phases and v a r i e t i e s l i s t e d i n order of decreasing s p e c i f i c g r a v i t y as expressed by the curves of Figure 23 and r e l a t i v e age as i n t e r p r e t e d from f i e l d work are compared as f o l l o w s : TABLE VI: S p e c i f i c G r a v i t y and R e l a t i v e Age of Phases S p e c i f i c G r a v i t y ' Hybrid Guichon Chataway LeRoy . Bethlehem ) ) Witches Brook ) Gump Lake Bethsaida same s p e c i f i c g r a v i t y R e l a t i v e Age Hybrid Guichon Chataway . LeRoy • Bethlehem Gump Lake Witches Brook Bethsaida With the p r o b l e m a t i c a l , ent. exception of the Gump Lake phase, where r e l a t i v e age i s c o r r e l a t i o n of s p e c i f i c g r a v i t y and r e l a t i v e age i s e x c e l l --68-S P E C I F I C G R A V I T Y • o r o r o M r o w r o W K J rj ro N) ro w ro ro N N ro ro ro ro Z $ 2 Z Z l $ & 2 Z 2 2 2 § n % % $ 8 % t % Figure 23 -69-utes to a lower s p e c i f i c g r a v i t y of some of the younger phases. P o s s i -b l y more i n t e r g r a n u l a r p o r o s i t y i n the younger phases i s a l s o a f a c t o r c o n t r i b u t i n g to lower s p e c i f i c g r a v i t y . STRUCTURE S t r u c t u r a l features of the Guichon Creek b a t h o l i t h i n c l u d e f o l i a - • t i o n , j o i n t s , shear and f a u l t zones and x e n o l i t h s . Some e a r l y f r a c t u r e s are now occupied by dykes or v e i n s . These s t r u c t u r a l data are shown on Figure 26. Also shown are those l i n e a r s observed on a i r photographs that may have some s t r u c t u r a l s i g n i f i c a n c e . EXTERNAL STRUCTURAL RELATIONS Both dis c o r d a n t and concordant r e l a t i o n s h i p s w i t h older rock are evident a t i n t r u s i v e contacts between the Guichon Creek b a t h o l i t h and old e r s t r a t i f i e d r o c k s . Discordant contact r e l a t i o n s h i p s are found a t the northwest margin of the b a t h o l i t h where bedding i n p r e b a t h o l i t h i c rocks i s truncated by i n t r u s i v e rock. A s i m i l a r r e l a t i o n s h i p occurs a t the southeast margin of the b a t h o l i t h , a t Craigmont, where N i c o l a rocks are truncated a t a low angle by the b a t h o l i t h (Rennie, 1962, p 50). At Spatsum on 'the west side, of the b a t h o l i t h the predominant dip of Cache Creek rock i s n o r t h e a s t e r l y , -70-that i s , towards the b a t h o l i t h (Carr, 1963, Figure 1). Layering i n a N i c o l a (?) roof remnant on the west side of Glossy Mountain s t r i k e s n o r t h e r l y and has a v e r t i c a l dip. Semi-concordant contact r e l a t i o n s h i p s can be observed at the flanks of the b a t h o l i t h , p a r t i c u l a r l y on i t s northwest side. Here, bedded N i c o l a sedimentary and volcanic rocks s t r i k e northeasterly and have moderate northwesterly dips away from the b a t h o l i t h suggesting displacement of older rocks above and to the side of the i n t r u s i v e magma. Si m i l a r , but poorly exposed, Nicola rock can be seen dipping away from the east side of the b a t h o l i t h . These semi-concordant r e l a t i o n s h i p s may, however, be the r e s u l t of l a t e r f a u l t i n g along both sides of the b a t h o l i t h . The Guichon Creek b a t h o l i t h i s a concordant i n t r u s i v e body i n the sense that i t i s elongate i n a d i r e c t i o n p a r a l l e l to the s t r u c t u r a l grain of older s t r a t i f i e d country rocks. A large roof remnant projects from beneath Kamloops v o l c a n i c cover and i s i n contact with Hybrid phase. Smaller roof remnants occur on the east side of the b a t h o l i t h within Hybrid phase. The degree of contamina-tio n of Hybrid phase increases approaching such roof remnants. O r i g i n a l l a y e r i n g remains v i s i b l e i n these remnants and they have undergone only low grade albite-epidote hornfels f a c i e s contact metamorphism. I t i s suspected that the heterogeneous assemblage of hybrid rocks at Spaist Mountain i n the west-central part of the b a t h o l i t h , shows incomplete a s s i m i l a t i o n and homogenization of a roof remnant that formerly existed at and above the present erosion surface. -71-INTERNAL STRUCTURAL RELATIONS X e n o l i t h s X e n o l i t h s are abundant i n older phases.at the b a t h o l i t h margin and show great v a r i a t i o n i n s i z e , degree of r e c r y s t a l l i z a t i o n , a s s i m i l a t i o n and grade of metamorphism. C e n t r a l phases of the b a t h o l i t h are r e l a t i v e l y x e n o l i t h - f r e e but some have been reported. A l a r g e x e n o l i t h of q u a r t z i t e can be seen i n Bethsaida phase near the middle of the b a t h o l i t h (White, personal communication). Some x e n o l i t h s have r e t a i n e d t h e i r granular t e x t u r e , have angular o u t l i n e s and are i n sharp contact w i t h the p l u t o n i c rock. Others are r i c h i n mafic m i n e r a l s , have rounded o u t l i n e s and i n -d i s t i n c t contacts w i t h . i n t r u s i v e rock. I t i s p o s s i b l e that f i n e - g r a i n e d m a f i c - r i c h . c l o t s i n Hybrid phase may represent x e n o l i t h s that have been a s s i m i l a t e d but "incompletely mixed w i t h magma. Contacts Phase contacts may be sharply i n t r u s i v e , b r e c c i a t e d or broadly g r a d a t i o n a l . The same contact may be shar p l y i n t r u s i v e a t one place and be g r a d a t i o n a l at another. C h i l l e d contacts were seen only i n two pl a c e s . At Gnawed Mountain there appears to be c h i l l i n g of Bethsaida phase a g a i n s t Bethlehem. An o f f - s h o o t of Bethsaida, l o c a l l y c a l l e d Spud -72-Lake Porphyry on Bethlehem Copper Corporation property, i s c h i l l e d a g a i n s t Guichon v a r i e t y . Late dykes commonly show c h i l l e d margins a g a i n s t o l d e r phases. Temperature d i f f e r e n c e s between successive phases appear to have been i n s u f f i c i e n t to cause c h i l l i n g except where f r a c t u r e s channelled magma i n t o r e l a t i v e l y cool outer margins. F o l i a t i o n F o l i a t i o n i n older phases shows that the b a t h o l i t h i s a dome w i t h s t e e p l y d i p p i n g sides (Figures 24 and 25). F o l i a t i o n of i n t r u s i v e phases of the b a t h o l i t h i s seen as planar o r i e n t a t i o n of mafic minerals i n out-crop and p r e f e r r e d o r i e n t a t i o n of p l a g i o c l a s e i n t h i n s e c t i o n . F o l i a t i o n of mafic minerals i s best developed i n the Hybrid phase and the Guichon v a r i e t y near the margin of the b a t h o l i t h and i n d y k e - l i k e v a r i e t i e s of Witches Brook phase. P r e f e r r e d o r i e n t a t i o n of p l a g i o c l a s e i s best d e v e l -oped i n the Hybrid phase and the Guichon v a r i e t y but i s common i n a l l phases except Bethsaida and Gump Lake. As i n d i c a t e d by Figures 25 and 26, f o l i a t i o n of mafic minerals p a r a l l e l s main b a t h o l i t h contacts and i n t e r n a l phase cont a c t s . Strong f o l i a t i o n i s best developed p a r a l l e l to margins of d y k e - l i k e bodies of Witches Brook phase. Along the west margin of the b a t h o l i t h n e a r l y a l l measured f o l i a t i o n s s t r i k e n o r t h e r l y and dip e i t h e r v e r t i c a l l y or s t e e p l y to the west. In Guichon and Chataway v a r i e t i e s i n the n o r t h - c e n t r a l p a r t of the b a t h o l i t h f o l i a t i o n dips moderately to the northwest and D1AGRAMATIC CROSS SECTION WEST TO EAST ACROSS CENTER OF THE GUICHON CREEK BATHOLITH WEST 6 0 0 0 -4 0 0 0 2 0 0 0 HORIZONTAL SCALE I MILE EAST - 6 0 0 0 2 0 0 0 Seo Level - 2 0 0 0 Sea Level - 2 0 0 0 POST-INTRUSIVE ROCKS INTRUSIVE ROCKS PRE-INTRUSIVE ROCKS SPENCES BRIDGE GROUP I S B I GNAWED MOUNTAIN PORPHYRIES I 7 I BETHSAIDA PHASE I 6 I WITCHES BROOK PHASE V A R I E T Y A V A R I E T Y B V A R I E T Y C • . - B E T H L E H E M PHASE GUMP LAKE PHASE I 3 I HIGHLAND VALLEY PHASE GUICHON V A R I E T Y | 2G I CHATAWAY V A R I E T Y . I £C I LE ROY I 2 L R I HYBRID PHASE I I 1 NICOLA GROUP CACHE CREEK GROUP I cc I FIGURE 24 -74--75-n o r t h . F o l i a t i o n s on the east f l a n k of the b a t h o l i t h vary i n dip from v e r t i c a l to moderate ea s t . At the south end of the b a t h o l i t h the f o l i a -t i o n seems to wrap around the b a t h o l i t h . Dips are moderate to steep souths- r l y . F o l i a t i o n i n Witches Brook and Bethlehem phases at the south end of the Bethsaida core s t r i k e s n o r t h e a s t e r l y and has gentle e a s t , v e r t i c a l , and moderate west d i p s . I t i s at an angle to f o l i a t i o n f a r t h e r south i n Highland V a l l e y and Hybrid phase. In summary, f o l i a t i o n tends to p a r a l l e l b a t h o l i t h contacts and to di p outwards, that i s , towards the margins of the b a t h o l i t h . L i n e a r s , probably F a u l t s Both g l a c i a l and s t r u c t u r a l l i n e a r s are detectable on a i r photo-graphs. G l a c i a l l i n e a r s are conspicuously superimposed on those of s t r u c t u r a l o r i g i n which may e i t h e r be masked or accentuated depending on whether the.trend of s t r u c t u r a l l i n e a r s i s across or p a r a l l e l to the d i r e c t i o n of i c e movement. Prominent l i n e a r s of probable s t r u c t u r a l o r i g i n are shown on Figure 26, and the frequency of t h e i r d i r e c t i o n i s shown on Figure 27. G l a c i a l l i n e a r s are excluded from t h i s f i g u r e . S t r u c t u r a l l i n e a r s are depressions which c o n t a i n r e l a t i v e l y e a s i l y erod-able m a t e r i a l . They extend f o r many m i l e s , have widely divergent trends and commonly t r a n s e c t prominent r i d g e s . Water courses f o l l o w and deepen the s t r u c t u r a l l i n e a r s and thereby modify the normal d e n d r i t i c drainage -76-p a t t e r n of the Guichon Creek b a t h o l i t h area. These features suggest that most s t r u c t u r a l l i n e a r s are l o c i of f a u l t s or shear zones. Most sulphide mineral occurrences on the Guichon Creek b a t h o l i t h are a s s o c i a t e d w i t h f a u l t s . The best known f a u l t s are therefore those o c c u r r i n g on mining p r o p e r t i e s where they are seen i n surface exposures, mine workings and i n d r i l l core. White, e t a l , describe s e v e r a l of these. Prominent f a u l t s on the Bethlehem Copper Corporation property s t r i k e w i t h -i n 20 degrees of north and dip s t e e p l y e i t h e r e a s t e r l y or w e s t e r l y . They are described as complicated branching or braided s t r u c t u r e s of sheared, comminuted, a l t e r e d rock and gouge ranging i n width from a few f e e t to more than 100 f e e t (White, e t a l , 1957, p 276). S i m i l a r f a u l t s occur on Trojan, K r a i n , O.K., and Skeena p r o p e r t i e s , a l l w i t h i n a s i x - m i l e r a d i u s of Bethlehem property. A notable f a u l t occurs on the Skeena pr o p e r t y . Here the f a u l t zone i s over 300 f e e t wide, s t r i k e s n o r t h e a s t e r l y and has i n t e r n a l s l i c k e n s i d e s d i p p i n g moderately e a s t e r l y (White, e t a l , 1957, p 276). L i n e a r s much more prominent than those r e p r e s e n t i n g known f a u l t s are v i s i b l e on a i r photographs. I t i s suspected that many of these prom-i n e n t l i n e a r s are f a u l t s c o n t a i n i n g wide zones of gouge and p o s s i b l y having large displacement. There i s , however, l i t t l e evidence of. l a r g e displacements on f a u l t s . No shear zones or f a u l t contacts were seen between phases to suggest large displacement, although i t i s p o s s i b l e t h a t such contacts occur but have been covered by g l a c i a l d r i f t . Northwesterly trending l i n e a r s between n o r t h 15 degrees west to _77_ Figure 27 _-78-north 45 degrees west, approximately p a r a l l e l to southeasterly movement of i c e , and north 5 degrees east are most numerous .(Figure 27) . The nor th -wester ly - t rending l inears are probably accentuated by ice scouring and are therefore more noticeable on a i r photographs. Therefore, i t i s poss ib le the greater number of l inears p lot ted with th i s trend may be of less s i g n i -f icance than a smaller number of l inears with trends across the d i r e c t i o n of ice movement. Jo ints At t i tudes of j o i n t sets were measured wi th in the batho l i th but not i n surrounding older rocks . In an attempt to in terpret j o i n t data , the map-area was div ided into seven sub-areas. Poles to planes of j o i n t s were p lot ted on an equal area stereonet. Stereograms of poles of j o i n t s for a l l phases and for each phase were made for each sub-area. These stereo -grams are shown on Figure 28. Appendix I I I i s a comparison of s tereo-grams. Interpretat ion of these data i s inconclusive because j o i n t data are too few and not uniformly d i s t r i b u t e d . There are no j o i n t data from s t r a t i f i e d rocks at the margin of the b a t h o l i t h . There are too few f i l l e d j o i n t sets to al low comparison with u n f i l l e d j o i n t s . The fac t that stereograms of j o i n t planes of a l l phases and for separate phases show that many j o i n t sets p e r s i s t over large areas, supp-or ts the contention that most u n f i l l e d j o i n t sets are secondary r e s u l t i n g -79-from r e g i o n a l s t r e s s a f t e r c r y s t a l l i z a t i o n of the b a t h o l i t h . J o i n t sets r e s t r i c t e d to small segments of the b a t h o l i t h and f i l l e d j o i n t sets may be primary, r e s u l t i n g from s t r e s s during c o o l i n g of the b a t h o l i t h or from pressure of c e n t r a l magma on c r y s t a l l i z e d phases at the b a t h o l i t h margin. - 8 0 -I I I GEOCHRONOLOGY INTRODUCTION This thesis includes ear ly . results obtained from the potassium-argon laboratory at the Univers i ty of B r i t i s h Columbia. The laboratory was establ ished to carry out geochronological studies of igenous rocks of B r i t i s h Columbia and to study theoret ica l problems of potassium-argon dating techniques. A major equipment grant from the National Research Council equipped the project i n 1962 and i t has since been supported by National Research Council operating grants. Professor W.H. White was responsible for set t ing up the potassium analys is laboratory. Professor G.P. Erickson designed and b u i l t the argon ext ract ion and a n a l y t i c a l equipment. J . E . Harakal supervised argon analyses and some analyses reported i n th is thesis were made by him. The laboratory became opera-t iona l late i n 1964 and during the course of work on the Guichon batho-l i t h about 50 age determinations were made, inc luding inter laboratory checks. While analyses were being done for th i s p ro ject , a s imi la r age dating program was being carr ied out by G.E. Dirom as a MASc thesis on porphyry dykes and major phases of the Guichon batho l i th occurr ing on the Bethlehem Copper Corporation property (Dirom, 1965). The r e s u l t s of the two projects are complementary and have been published (White, et a l , 1967). Appendix I of t h i s t h e s i s i n c l u d e s an account of sampling methods, b i o t i t e s e p a r a t i o n , potassium analyses, argon analyses, 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 , K/A i n t e r l a b o r a t o r y comparisons, and d e s c r i p t i o n of b i o t i t e samples used i n age determinations. GUICHON BATHOLITH K/A RESULTS A n a l y t i c a l data are l i s t e d i n Table V I I . The apparent age of each sample was c a l c u l a t e d on the b a s i s of those data and 1" values show the estimated l i m i t s of e r r o r . Figure 29 d i a g r a m a t i c a l l y shows 26 age determinations centered around an average age of 198 1" 8 my. They are shown on t h i s f i g u r e from o l d e s t to youngest on the b a s i s of g e o l o g i c a l f i e l d r e l a t i o n s h i p s . Dirom (1965) obtained concordant ages f o r hornblende and b i o t i t e f o r the Guichon phase on Bethlehem Copper Corporation property and f o r Bethlehem phase using sample K63-115 which was taken 6 m i l e s to the southwest. G e o l o g i c a l evidence places the age of the Guichon b a t h o l i t h w i t h i n l i m i t s of e a r l y Upper T r i a s s i c and Middle J u r a s s i c ( D u f f e l l and McTaggart, 1952). Major phases of the b a t h o l i t h can be placed i n approximate order of r e l a t i v e age on the b a s i s of g e o l o g i c a l evidence. Figure 29 r e l a t e s phases i n approximate order of age to K/A apparent ages obtained during the course of t h i s study. The f i g u r e shows i t i s H Y B R I D G U I C H O N C H A T A W A Y L E R O Y G U M P L A K E B E T H L E H E M W I T C H E S B R O O K B E T H S A I D A i AGE 210 my 2 0 0 my T 0 0 190 my L — r 0 • 6 0 © o 0 ---,-<) 0 © 0 • CD 0 .0. 0 6 6 00 r o • Figure 2 9 ^ Biotite determination |^ |] Biotite determination G.E.Dirom [ J Hornblende determination G.E.Dir Graphic representation of K/A age determinations with phases listed in order .of decreasing age by geologic considerations. TABLE V I I : Potassium A n a l y t i c a l Data % K w i t h Std.Dev. and Sample No. Phase M i n e r a l No. samples analysed K63-13 Hybrid B i o t i t e 4.49 + 0.02 (4) K64-156a ' Hybrid II 6.73 + 0.01 (6) K63-223 Guichon u 5.77 + 0.02 (4) K64-116a Chataway 5.24 + 0.04 (4) K64-220 Chataway-LeRoy 5.20 + 0.02 K63-37 LeRoy » 6.42 + 0.03 (4) K64-101 LeRoy it 5.16 + 0.05 (4) K'64-98-1 Gump Lake II 5.95 + 0.01 (4) K63-115 Bethlehem 5.90 + • 0.07 (4) K64-102 Witches Brook 4.91 + 0.03 (4) K64-105-I Witches Brook » 6.53 + 0.04 (4) K63-171 Witches Brook „ 6.59 + 0.06 (4) K64-203 Witches Brook 4.42 + 0.02 (4) K64-17 Witches Brook „ 3.59 + 0.02 (4) K63-187 Bethsaida 4.48 + 0.02 (4) K63-231 Bethsaida 5.86 + 0.07 (4) K63-114 Fragmental 6.99 (2) R h y o l i t e -84-TABLE VIII: Argon A n a l y t i c a l Data and Model Age Samp il e No. Phase K63-•13 Hybrid K64-•156a Hybrid K63- 223 Guichon K64-•116a Chataway K64-•220 Chataway/ LeRoy K63-•37 LeRoy K64-•101 LeRoy K64-•98-1 Gump Lake K63-•115 Bethlehem K64- 102 Witches Brook K64-•105-1 Witches Brook K63- 171 K64- 203 K64-17 K63-187 K63-231 K63-114 A 4 0 rad A 4 0 rad A 4 0 t o t a l (10" 5cc STP/g) 0.85 3.795 0.91 3.716 0.52 5.785 0.93 5.659 0.87 4.689 0.80 4.155 0.77 4.358 0.92 4.325 0.30 5.390 0.78 5.385 0.90 4.295 0.37 4.817 0.91 4.919 0.90 4.307 0.90 4.788 0.87 4.055 0.91 4.077 0.90 5.442 0.93 5.536 0.75 5.263 0.64 3.759 0.79 3.750 0.74 3.093 0.80 3.590 0.88 3.648 0.86 5.044 0.88 1.389 0.83 1.433 Radiometric Dates K 4^ & Assigned E r r o r 0.01249 202 + 8 0.01223 198 + 8 0.01270 206 + 10 0.01243 201 + 8 0.01201 195 + 8 0.01171 190 + 8 0.01239 201 + 8 0.01230 199 + 8 0.01241 201 + 8 0.01240 201 + 8 0.01231 199 + 8 0.01196 194 + 10 0.01222 198 + 8 0.01199 195 + 8 0.01196 195 + 8 0.01221 198 + ' 8 0.01228 199 + 8 0.01230 198 + 8 0.01253 203 + 8 0.01181 192 + 8 0.01257 203 8 0.01254 203 + 8 0.01272 206 + 8 0.01184 192 + 8 0.01204 195 + 8 0.01272 206 8 0.002935 49 + 3 0.003032 51 3 Note: Constants 0.58 x 1 0 " 1 0 y r " 1 B = 4.72 x 1 0 " 1 0 y r " 1 4 0K/K = 1.181 x 10" 4 -85-TABLE IX:. Potassium Data from Bethlehem Copper Corporation Property (Dirom) No. Samples Sample No. Phase M i n e r a l % K Analysed G.D. -12 Guichon B i o t i t e 5.56 (2) Hornblende 0.424 (2) G.D. -4 Guichon Hornblende/Amphibole 0.169 (3) K63- 115 Bethlehem Hornblende 0.387 (2) G.D. -11a Bethlehem Hornblende/Amphibole 0.162 (2) K63- 222 Witches Brook B i o t i t e 7.16 (2) G.D. -2 P3 Porphyry Hornblende/Amphibole 0.140 (3) G.D-10 P3 Porphyry Hornblende/Amphibole 0.292 (2) G.D. -5 Da c i t e B i o t i t e 5.56 (2) Porphyry K63- 240 Iona B r e c c i a B i o t i t e (W.H. White) 5.60 (4) TABLE X: Argon Data from Bethlehem Copper Corporation Property (Dirom) A 4 0 rad A 4 0 rad A 4 0 rad Radiometric A 4 0 t o t a l K 4 0 Dates & Sample No. Phase (10" 5cc STP/g) Assigned E r r G.D.-12 Guichon 0.83 4.663 0.01239 201 + 8 . ! ! 0.60 0.3629 0.01264 205 + 8 G.D.-4 ! ! 0.60 0.1474 0.01285 208 t 8 K63-115 Bethlehem 0.39 0.3121 0.01192 194 t 10. G.D.-11a . 0.44 0.1305 0.01193 194 + 10 K63-222 Witches Brook 0.87 5.903 0.01218 198 + 8 G.D.-2 P3 Porphyry . 0.24 ; 0.09845 . 0.01041 170 ± 12 0.39 0.09879 0.01044 171 + 12 G.D.-10 P3 Porphyry 0.53 0.2432 0.01230 199 + 8 G.D.-5 Dacite Porphyry 0.50 4.717 0.01253 203 + 8 K63-240 Iona B r e c c i a 0.84 4.643 0.01225 199 ± 8 (W.H. White) -86-not p o s s i b l e to d i f f e r e n t i a t e among va r i o u s phases on the b a s i s of K/A apparent ages because v a r i a t i o n s are w i t h i n a n a l y t i c a l l i m i t s of un-c e r t a i n t y of the techniques used. B i o t i t e of the major phases began . r e t a i n i n g argon a t approximately, the same time centered around 198 1" 8 my. ago. Iona B r e c c i a , a b r e c c i a pipe o c c u r r i n g on the Bethlehem Copper Corporation property, c o n t a i n i n g hydrothermal(?) b i o t i t e , the youngest b i o t i t e observed on the b a t h o l i t h , a l s o gave a s i m i l a r i s o t o p i c age of 199 1 8 my. (White, e t a l , 1967, p 686). There are a t l e a s t two p o s s i b i l i t i e s to e x p l a i n the remarkable u n i f o r m i t y of i s o t o p i c ages obtained f o r the v a r i o u s phases of the Guichon b a t h o l i t h . (1) The phases of the b a t h o l i t h are a l l o l d e r than 198 my. but underwent r e g i o n a l metamorphism at that time which r e s e t the argon^O " c l o c k s " i n b i o t i t e . (2) The phases of the b a t h o l i t h were emplaced during a short p e r i o d of time before 198 my. so that they were a l l r e l a t i v e l y hot a t the same time, and began to r e t a i n argon at about the same time. The f i r s t p o s s i b i l i t y i s i n c o n s i s t e n t w i t h g e o l o g i c a l evidence w i t h -i n the b a t h o l i t h and the N i c o l a rocks which i t i n t r u d e s . The N i c o l a country rock has been thermally metamorphosed a t contacts w i t h the i n t r u s i v e rocks but does not show the same degree of metamorphism a few hundred f e e t away from the c o n t a c t s . I t would be expected that a r e g i o n a l metamorphic event of s u f f i c i e n t i n t e n s i t y to a l l o w a l l argon to escape from b i o t i t e and hornblende would have i t s mark on the o l d e r rock around the b a t h o l i t h . -87-There i s no evidence of metamorphism of i n t r u s i v e rock 200 my. ago of s u f f i c i e n t i n t e n s i t y to r e l e a s e a l l argon from a l l b i o t i t e and a l l hornblende throughout the b a t h o l i t h . O r i g i n a l rock t e x t u r e s and s t r u c t -ures seem to be unchanged. The i n t r u s i v e rock r e t a i n s " f l o w s t r u c t u r e " shown by p r e f e r r e d o r i e n t a t i o n of mafic minerals and p l a g i o c l a s e . Concordant ages i n hornblende and b i o t i t e i s considered by some to be evidence that the rock has not undergone a l a t e r metamorphic event ( A l d r i c h , e t a l , 1960). I t i s har d l y conceivable that f a i l i n g r e -c r y s t a l l i z a t i o n and complete l o s s of argon that both b i o t i t e and horn-blende could have both l o s t the proper r a t i o of argon by heating to . r e s u l t i n concordant ages of 198 my. The second p o s s i b i l i t y , that 198 1 " 8 my. represents the time that c r y s t a l l i z a t i o n and c o o l i n g of a l l phases had progressed s u f f i c i e n t l y to r e t a i n r a d i o g e n i c argon, i s c o n s i s t e n t w i t h g e o l o g i c evidence. No i n t e r v a l of time can be given f o r p e r i o d of emplacement of the b a t h o l i t h . I t can be s a i d , however, that: (1) P a u c i t y of c h i l l e d contacts i n d i c a t e s most phases of the batho-l i t h were hot at approximately the same time. (2) . B i o t i t e of the major phases began r e t a i n i n g argon a t approx-imately the same time centered around 198 - 8 my. ago. (3) No s i g n i f i c a n t metamorphic event has a f f e c t e d the rocks of the Guichon Creek b a t h o l i t h since that time. (4) G e o l o g i c a l evidence shows that emplacement of the b a t h o l i t h occurred a f t e r Karnian time. Argon must have begun to accumu-l a t e i n b i o t i t e and hornblende w e l l before Middle J u r a s s i c because pebbles of the b a t h o l i t h occur i n conglomerate of t h i s age. -88-IV PETROGENESIS ENVIRONMENT OF EMPLACEMENT Buddington~describes c r i t e r i a i n d i c a t i v e of emplacement of plutons i n p r o g r e s s i v e l y deeper environments or zones of i n c r e a s i n g pressure, temperature and w a l l r o c k m o b i l i t y . These zones are c a l l e d "epizone", "mesozone", and "catazone" (Buddington, 1959, p 676). Plutons of the epizone are probably emplaced a t a shallow depth between 0 to 6 m i l e s w i t h w a l l r o c k temperature below 300°C. Plutons of the mesozone are considered to be emplaced between 4 to 10 m i l e s of the surface w i t h w a l l r o c k temperatures ranging between 250 and 500°C. Plutons of the catazone are emplaced between 6 to 12 m i l e s depth w i t h w a l l r o c k tempera-tures the order of 600,to 700°C (Figure 30). C r i t e r i a that Buddington mentions as i n d i c a t i v e of epizone and mesozone are l i s t e d i n Table IV (Buddington, 1959, pp 671-747). An a s t e r i s k precedes c r i t e r i a which are seen i n the Guichon Creek b a t h o l i t h . A " ? " i n d i c a t e s u n c e r t a i n t y . , -89-TABLE XI : C r i t e r i a I n d i c a t i v e of Plutons of the Epizone, Mesozone, and Catazone (Buddington, 1959, pp 671-747) Epizone (a) Young age. (b) L a r g e l y or wholly d i s c o r d a n t to country rock. * ( c ) Small p o r t i o n of the b a t h o l i t h i s composed of quartz d i o r i t e ; d i v e r s i t y r e s u l t s , i n p a r t by i n c o r p o r a t i o n , more, or l e s s i n p l a c e , of country rock. ?(d) Roof pendants common. (Roof remnants are present but are not common on the Guichon Creek b a t h o l i t h ) . ?(e) Homophanous, without l i n e a t i o n or f o l i a t i o n . (Appears to be true of young c e n t r a l phases). ? ( f ) V o l c a n i c rocks i n c l o s e genetic r e l a t i o n s h i p . (Porphyry dykes are a s s o c i a t e d w i t h the younger phases of the Guichon Creek b a t h o l i t h ) . (g) Country rock r e l a t i v e l y unmetamorphosed. (h) Zoned mineral v e i n s . * ( i ) P e r i p h e r a l outward deformation of side w a l l s , ( j ) Most plutons are small but there are many examples of b a t h o l i t h s i z e , (k) A s s o c i a t e d w i t h r i n g dyke complexes and cauldron subsidence. (1) E a r l i e r smaller members of a complex pluton show c h i l l i n g a g a i n s t country rock. *(m) Late stage a p h a n i t i c or p o r p h y r i t i c dykes and lamprophyre dykes are :• common. (Lamprophyre dykes are not common), (n) Pegmatite v e i n s are minor i n stocks although l o c a l " n e s t s " may occur. A l a s k i t e or a p l i t e may be w e l l developed i n b a t h o l i t h s . (o) M i a r o l i t i c .structure i s common i n l e u c o g r a n i t e or a l a s k i t e . ?(p) Granophyric t e x t u r e . (This, may be the r e s u l t of d e u t e r i c a l t e r a -t i o n ) . (q) S a t e l l i t i c l a c c o l i t h s . ( r ) Emplacement by metasomatism uncommon, contacts are u s u a l l y sharp. * ( s ) Evidence of emplacement as h i g h l y v i s c o u s magma. * ( t ) B r e c c i a p i p e s . Mesozone * ( a ) Degree of metamorphism of country rocks not more intense than g r e e n - s c h i s t and epidote-amphibolite f a c i e s (400 to 500°C). (b) No apparent d i r e c t r e l a t i o n s h i p between plutons.and v o l c a n i c r o c k s . * ( c ) Complex emplacement r e l a t i o n s h i p s to country rock; i n p a r t d i s c o r d -ant, i n p a r t concordant.. L o c a l replacement. -90-Environment of Emplacement of Plutons M i l e s depth 4 6 8 10 12 -! 1 i : ! I I Epizone Mesozone Cotozone Figure 3 0 (After Buddington 1 9 5 9 ; p. 6 7 7 ) -91-*(d) Planar f o l i a t i o n i s o f t e n w e l l developed, e s p e c i a l l y i n outer . p o r t i o n s of the p l u t o n , but i s commonly l o c a l , e l u s i v e or m i s s i n g i n the core. * ( e ) Younger u n i t s may c r o s s c u t f o l i a t i o n of older u n i t s , or the s t r u c t u r e may l o c a l l y be independent of boundary u n i t s w i t h i n a composite p l u t o n . * ( f ) A s s i m i l a t i o n may be s i g n i f i c a n t i n border or roof zones, (g) Wallrocks i n contact zones o f t e n show development of a steep s c h i s t o s i t y conformable with the contact and a l i n e a r s t r u c t u r e more or l e s s p a r a l l e l to the dip i n d i c a t i n g flowage i n a s u b v e r t i -c a l d i r e c t i o n . Bedded rocks or dykes a t large angles to the cont-act may be crumpled back on themselves as though formed by outward pressure from the p l u t o n . *(h) Emplacement by r e c o n s t i t u t i o n and replacement i s commonly absent or subordinate. ? ( i ) C h i l l border f a c i e s , i n the sense of a p h a n i t i c t e x t u r e , are absent. (Present i n the youngest phase of the Guichon b a t h o l i t h ) . * ( j ) Migmatites are absent or subordinate. * ( k ) Pegmatites and a p l i t e s common e s p e c i a l l y i n the border zones. They may have a r a d i a l f a b r i c . *(1) M i a r o l i t i c s t r u c t u r e i s absent, (m) Marginal f i s s u r e s w i t h inward d i p s , i n p a r t l i n e d w i t h a p l i t e or pegmatite, may be present l o c a l l y i n border zones. *(n) Contact metamorphic aureoles may be w e l l developed. Features which occur i n both Epizone and Mesozone *( a ) Composite c h a r a c t e r . *(b) Domical or arch-shaped r o o f . (Suggested by f o l i a t i o n i n Hybrid and Highland V a l l e y phases). According to Buddington's c r i t e r i a , the Guichon Creek b a t h o l i t h would be c l a s s e d as mesozonal to e p i z o n a l . Mesozonal features are char-a c t e r i s t i c of the older phases a t the outer margin of the b a t h o l i t h . Complex d i s c o r d a n t , and i n p a r t concordant, emplacement r e l a t i o n s h i p s occur. The surrounding country rock has been metamorphosed to a l b i t e -epidote or hornblende h o r n f e l s f a c i e s . The contact aureole i s s m a l l , g e n e r a l l y 1/8 to 1/2 m i l e . A s s i m i l a t i o n of country rock appears to have -92-been s i g n i f i c a n t . No c h i l l i n g i s apparent at the outer margin of the b a t h o l i t h or at contacts between border phases. The phases at the margin of the b a t h o l i t h have a f a i r l y w e l l developed planar f o l i a t i o n of mafic minerals and a w e l l developed p r e f e r r e d o r i e n t a t i o n of euhedral p l a g i o c l a s e c r y s t a l s . This f o l i a t i o n and p r e f e r r e d o r i e n t a t i o n i s c r o s s c u t by younger u n i t s . There i s no apparent d i r e c t r e l a t i o n s h i p between plutons and v o l c a n i c rock. A number of features of young c e n t r a l phases suggest emplacement i n a shallower environment than the o l d e r phases. The Bethsaida phase i s homophanous, without l i n e a t i o n or f o l i a t i o n . Late stage a p h a n i t i c and p o r p h y r i t i c dykes are common. There are some c h i l l e d contacts be-tween the Bethsaida and the Bethlehem, and commonly the l a t e porphyry dykes are c h i l l e d a t t h e i r contact w i t h Bethsaida, Bethlehem and High*-land V a l l e y phases. Pipe b r e c c i a s are common i n the younger phases i n the center of the b a t h o l i t h and where they do occur i n older phases near the b a t h o l i t h margin, they are always i n a s s o c i a t i o n w i t h porphyries or bodies of younger phases. I t i s p o s s i b l e that the o l d e s t phases were emplaced i n a mesozonal environment while e r o s i o n was i n progress. Perhaps successive phases of the b a t h o l i t h were emplaced at p r o g r e s s i v e l y shallower depths as a r e s u l t of e r o s i o n of o v e r l y i n g Upper T r i a s s i c (Karnian) formations. Thereby, e p i z o n a l features of younger phases were superimposed on e a r l i e r mesozonal f e a t u r e s . An a l t e r n a t e p o s s i b i l i t y i s that the b a t h o l i t h penetrated en masse s u c c e s s i v e l y higher i n t o the c r u s t during emplace--93-ment of younger c e n t r a l phases. The o v e r l y i n g u p l i f t e d m a t e r i a l would be eroded to r e s u l t i n an e p i z o n a l environment of emplacement of younger phases. Although f a u l t i n g and shearing has occurred i n older rocks of N i c o l a and Cache Creek groups near the margin of the b a t h o l i t h , there • i s l i t t l e evidence that f a u l t i n g was a major mechanism of emplacement of the b a t h o l i t h . Carr (1963, p 44) i l l u s t r a t e s grabens almost completely surrounding the b a t h o l i t h . A large n o r t h w e s t e r l y graben l i e s a few miles to the west of the exposed b a t h o l i t h margin. The grabens are apparently pre-Middle J u r a s s i c because they were f i l l e d by marine Middle J u r a s s i c and younger s t r a t a to the east of which was .... " a high landmass i n which the Guichon b a t h o l i t h , not long emplaced, was bared to e r o s i o n . " . . ( C a r r , 1963, p 44). The grabens record subsequent movement by t i l t i n g of s t r a t a u n t i l T e r t i a r y . The grabens apparently had l i t t l e to do w i t h emplacement of the Guichon b a t h o l i t h because the f i r s t sediments to appear w i t h i n them c o n t a i n pebbles and cobbles of the b a t h o l i t h . F a u l t b r e c c i a s a t the west margin of the b a t h o l i t h commonly c o n t a i n a few g r a n i t i c fragments which are i n d i c a t i v e of movement a f t e r c r y s t a l l i -z a t i o n of the magma. Some upward movement of older c r y s t a l l i z e d phases a t the margin of the b a t h o l i t h probably occurred during emplacement of younger c e n t r a l phases. There i s , however, no intense shearing of the' Hybrid phase a t the b a t h o l i t h margin to i n d i c a t e that i n t r u s i o n of c r y s t a l l i z e d outer phases of the b a t h o l i t h i n t o s u c c e s s i v e l y higher l e v e l s of the c r u s t was a major mechanism of emplacement of the b a t h o l i t h . -94-The p o s s i b i l i t y that e r o s i o n of o v e r l y i n g sediments took place during emplacement of the Guichon b a t h o l i t h i s suggested by absence of Lower J u r a s s i c sediments. Middle J u r a s s i c conglomerate unconformably o v e r l i e s the b a t h o l i t h and Upper T r i a s s i c (Karnian) r o c k s . I f post K a r i a n - pre-Middle J u r a s s i c rocks were deposited they must have been eroded before Middle J u r a s s i c . In order to have d e p o s i t i o n of Lower J u r a s s i c sediments i t would be necessary to p o s t u l a t e a b a s i n of de-p o s i t i o n o c c u r r i n g simultaneously above shallow f o r c e f u l emplacement of the b a t h o l i t h . For the above reasons the hypothesis fraught w i t h the l e a s t number of d i f f i c u l t i e s i s that e r o s i o n during i n t r u s i o n changed the environment of emplacement from mesozonal to e p i z o n a l depths. Figure 30 i n d i c a t e s that from 5000 to 15000 f e e t of o v e r l y i n g , s t r a t a would have to be removed. Larsen (1945, p 415) estimates the time r e q u i r e d f o r c r y s t a l l i z a -t i o n of the S i e r r a Nevada b a t h o l i t h i s of the order of a m i l l i o n years. L o v e r i n g (1955, p 277), however, s t a t e s that a m i l l i o n years i s probably too short a time. Potassium/argon age determinations p r e s e n t l y a v a i l -able f o r the S i e r r a Nevada b a t h o l i t h i n d i c a t e at l e a s t three separate periods of i n t r u s i o n . The f i r s t group span 170 to 210 m i l l i o n years (Late T r i a s s i c or E a r l y J u r a s s i c ) , and the second group span 20 m i l l i o n years from 125 to 145 m i l l i o n years (Late J u r a s s i c ) (Bateman & Eaton, 1967, p 1409). The t h i r d group spans a p e r i o d of 18 m i l l i o n years i n lower Upper Cretaceous time and, according to C u r t i s et a l (1958), age d a t i n g suggests an i n t e r v a l of approximately 2 m i l l i o n years between -95-i n t r u s i o n s . Most i n t r u s i o n s appear to have been almost completely c r y s t a l l i z e d before succeeding i n t r u s i o n s were emplaced. The suggested i n t e r v a l of 2 m i l l i o n years f o r emplacement and c r y s t a l l i z a t i o n of each i n t r u s i o n i s i n f a i r agreement w i t h Larsen's estimate ( C u r t i s , e t a l , 1958, p 12). I f a p e r i o d of 4 m i l l i o n years was r e q u i r e d f o r emplacement and c r y s t a l l i z a t i o n of the older phases of the Guichon Creek b a t h o l i t h , a r a t e of e r o s i o n of one f o o t every 200 to 800 years would change the environment of emplacement from mesozonal to subvolcanic before i n t r u s i o n of the younger phases. MODE OF EMPLACEMENT Emplacement of the Guichon Creek b a t h o l i t h by g r a n i t i z a t i o n of older s t r a t i f i e d rocks does not seem probable; f i r s t l y , because f o l i a -t i o n of mafic minerals of Hybrid and Guichon rocks and p r e f e r r e d o r i e n t a -t i o n of p l a g i o c l a s e i n a l l but the youngest phases, suggests movement of p a r t i a l l y c r y s t a l l i z e d magma during emplacement. Late minerals to c r y s t a l l i z e i n Hybrid and Guichon rocks and p l a t y mafic minerals i n phases of intermediate age show no p r e f e r r e d o r i e n t a t i o n as would be expected i f alignment of p l a g i o c l a s e i n these rocks was simply the r e s u l t of s t r e s s . Secondly, a l l "phases" can be seen, i n i n t r u s i v e contact w i t h other "phases" or older s t r a t i f i e d rock. The contacts are "sharp" and occur -96-between la r g e i n t r u s i v e masses, small i r r e g u l a r d y k e - l i k e bodies, dykes w i t h r e g u l a r c h i l l e d margins, and contact b r e c c i a s . T h i r d l y , a narrow halo of low grade thermal metamorphism suggests magmatic r a t h e r than metasomatic o r i g i n . Such a contact i s s a i d to be disharmonious and i n d i c a t i v e of emplacement by magma (Walton, 1955, pp 8-9).. ..."The only adequate means as yet known of i n t r o d u c i n g a l a r g e , l o c a l i z e d source of heat i n t o a r e l a t i v e l y shallow, unmetamorphosed sedimentary environment i s ' by i n t r o d u c i n g an adequate amount of hot m a t e r i a l w i t h high heat c a p a c i t y - or to put i t b l u n t l y , by i n t r u s -i o n of hot, mobile rock m a t e r i a l - or even more b l u n t l y , by hot magma." (Walton, 1955, p 1 0 ) . For the above reasons, the Guichon Creek b a t h o l i t h i s considered to have been emplaced as i n t r u s i v e magma. Processes of Emplacement The Guichon Creek b a t h o l i t h appears to have been emplaced i n a roughly c o n c e n t r i c s e r i e s of p a r t l y c r y s t a l l i z e d magmatic pulses by a combination of w a l l r o c k s t o p i n g , a s s i m i l a t i o n of s t r a t i f i e d country rock, f o r c e f u l i n t r u s i o n , and p o s s i b l y p a r t l y as a r e s u l t of d i f f e r e n t - , i a l g r a v i t a t i o n a l e f f e c t s on the g r a n i t i c m a t e r i a l r e l a t i v e to surround-i n g country rock. Emplacement of the b a t h o l i t h p a r t l y by magmatic stoping i s suggested by the presence of x e n o l i t h s . They are abundant i n the older phases f o r a d i s t ance of s e v e r a l hundred f e e t inwards from the b a t h o l i t h margin. P a u c i t y of x e n o l i t h s i n younger c e n t r a l phases i s not e a s i l y e x p l a i n e d but perhaps the x e n o l i t h s were completely a s s i m i l a t e d and inc o r p o r a t e d - 9 7 -i n the magma before they reached the present erosion leve l i n the b a t h o l i t h . Possibly the magma at the top of the magma chamber was enriched i n v o l a t i l e s and was s u f f i c i e n t l y react ive to ass imi late and homogenize most of the inc lus ions . Ass imi la t ion and incorporat ion of wal l rock mater ia l i s suggested by inhomogeneities i n texture and composition near the outer contact , as compared to a r e l a t i v e l y homogeneous composition i n the middle part of the b a t h o l i t h . The Hybrid phase grades outwards across the ba tho l i th margin from only s l i g h t l y contaminated in t rus ive rock to highly contam-inated rock, charged with xeno l i ths , to r e c r y s t a l l i z e d p re -ba tho l i th rock or metasomatized ep idote -a lb i te to hornblende hornfels to r e l a t i v e l y unmetamorphosed s t r a t i f i e d - country rock. Marked textura l and composit-iona l changes in in t rus ive rock at the batho l i th margin may be a r e s u l t of compositional di f ferences i n assimi lated m a t e r i a l . Xeno l i ths , most abundant wi th in 1/4 mile of the outer contact, show a gradation i n degree of r e c r y s t a l l i z a t i o n , metasomatism and a s s i m i l a t i o n . They may grade from r e l a t i v e l y unchanged older rock showing sharp contacts, to . dark m a f i c - r i c h c lo ts with i n d i s t i n c t out l ine i n in t rus ive rock. Degree, of metamorphism, r e c r y s t a l l i z a t i o n and a s s i m i l a t i o n of xenol i ths are thought-.to be a function of thei r r e a c t i v i t y , composition, s i z e , pressure-temperature condit ions wi th in the magma, amount of v o l a t i l e s present and length of time of immersion in the magma (Lovering, 1955, p 269).. Hybrid rocks farther from the contacts are more homogeneous i n texture and composition as a r e s u l t of complete mixing of ass imi lated m a t e r i a l . -98-I n view of the width of the contaminated zone, p a r t i c u l a r l y on the west side of the b a t h o l i t h , a s s i m i l a t i o n appears to have played an important r o l e i n the development of the b a t h o l i t h . Table I I I , Average Modes of Phases and V a r i e t i e s , shows.that the p l a g i o c l a s e and b i o t i t e content i s f a i r l y uniform. There i s , however, an increase i n amount of opaque minerals (magnetite l a r g e l y ) , hornblende and augite i n h y b r i d r o c k s . Although a l l phases have s i m i l a r p l a g i o c l a s e content, p l a g i o c l a s e of the h y b r i d rocks i s r i c h e r i n Ca. Hybrid rocks c o n t a i n l e s s o r t h o c l a s e and quartz than phases near the middle of the b a t h o l i t h . No chemical analyses were made of the rocks so no d i r e c t compositional comparisons can be made between h y b r i d rocks and the High-land V a l l e y phase which i s thought to c l o s e l y represent the composition of the o r i g i n a l magma. On the b a s i s of mineralogy, i t appears that h y b r i d rocks have been enriched i n Ca, Fe, Mg, OH and are poorer i n S i , K and p o s s i b l y Na. The process of emplacement of a p a r t l y c r y s t a l l i z e d magma by a s s i m i -l a t i o n of presumably more b a s i c m a t e r i a l s , cannot e a s i l y be e x p l a i n e d . A d d i t i o n of any b a s i c m a t e r i a l should r a i s e temperature of c r y s t a l l i z a -t i o n . Any a d d i t i o n of b a s i c m a t e r i a l to a p a r t l y c r y s t a l l i z e d magna should r e s u l t i n r a p i d c r y s t a l l i z a t i o n . Bowen (1956, pp 175-223) has shown that any minerals high on the continuous or discontinuous r e a c t i o n s e r i e s added to an a c i d i c melt, w i l l cause an exothermic r e a c t i o n and w i l l be made over i n t o phases i n e q u i l i b r i u m w i t h the melt. Contamination of magma can be brought about i n a q u a n t i t a t i v e l y important amount by ex--99-change of m a t e r i a l s between magma and w a l l r o c k i f an exchanging medium of v o l a t i l e - r i c h s o l u t i o n s are present (Nockolds, 1933, pp 561-583). Nockolds (1933, p 584) pointed out that contamination of magma i s i n -creased by d i s i n t e g r a t i o n of w a l l r o c k and x e n o l i t h s and i n c o r p o r a t i o n of r e l e a s e d minerals i n t o the-magma. I t i s suggested that v o l a t i l e s may have d i f f u s e d and concentrated a t the margin of the b a t h o l i t h , i n an environment of lower temperature and pressure, i n order to e q u a l i z e the p a r t i a l pressure of v o l a t i l e s throughout the magma (Kennedy, 1955, pp 489-503). A d d i t i o n a l v o l a t i l e s may have been derived from s t r a t i f i e d p r e - b a t h o l i t h r o c k s . The presence of v o l a t i l e s i s suggested by the r e l a t i v e abundance of hydrous hornblende i n rocks on both sides of the b a t h o l i t h 1 s outer contact. V o l a t i l e s would not only provide a medium of exchange of m a t e r i a l from magma to i n c l u s i o n s and country rock, but would a l s o lower temperature of c r y s t a l l i z a t i o n and f u r t h e r a s s i s t the process of a s s i m i l a t i o n . I t i s p o s s i b l e that f o r c e f u l i n t r u s i o n a l s o played an important r o l e i n emplacement of the b a t h o l i t h but i t i s a d i f f i c u l t process to demonstrate. Sharp contacts of apophyses of younger phases, i r r e g u l a r d y k e - l i k e bodies, b r e c c i a a t the b a t h o l i t h margin, i r r e g u l a r dykes w i t h c h i l l e d margins, and pipe b r e c c i a s , may have been caused by f o r c e f u l i n t r u s i o n of magma. N i c o l a rocks are i n concordant contact on the east and west sides of the b a t h o l i t h s t r i k i n g p a r a l l e l to and dipping away from i t s outer margin, an a t t i t u d e suggestive of being forced upwards •and outwards by magmatic pressure. This apparent concordant r e l a t i o n --100-s h i p could, however, be the r e s u l t of l a t e deformation i n grabens f l a n k -ing the b a t h o l i t h . A few mi l e s south of A s h c r o f t , Middle J u r a s s i c rocks which unconformably o v e r l i e the b a t h o l i t h have s i m i l a r a t t i t u d e s . According to Walton (1955, p 7 ) , s a l t domes demonstrate c l e a r l y how l i g h t mobile m a t e r i a l impelled by nothing more than g r a v i t y can punch • i t s way through tens of thousands of f e e t of o v e r l y i n g s t r a t a . Apparently s t r u c t u r a l deformation produced by such processes i s s c a r c e l y n o t i c e a b l e beyond a few hundred meters from the edge of the i n t r u s i v e mass and i s evident only when the deformed rocks are w e l l s t r a t i f i e d and not other-wise deformed. The s p e c i f i c g r a v i t y of uncontaminated phases i s lower than country rock. In general the s p e c i f i c g r a v i t y of the i n t r u s i v e rocks increases w i t h i n c r e a s i n g amount of contamination. I t i s p o s s i b l e t h a t the e f f e c t of g r a v i t y on the d i f f e r e n t d e n s i t i e s of magma and surrounding country rock played some p a r t i n emplacement of the Guichon b a t h o l i t h . Magmatic Processes Textural and compositional d i f f e r e n c e s between phases and the i n t r u s -i v e nature of i n t e r n a l contacts suggests that the magma was emplaced as a s e r i e s of pu l s e s . Magmatic pulses may r e s u l t from c y c l i c d i f f u s i o n of v o l a t i l e s u n t i l p a r t i a l pressure i s high-enough to overcome c o n f i n i n g pressure. The major c o n t r o l would be d i f f u s i o n r a t e of water i n the magma (Kennedy, 1955, p 495). While successive pulses of magma were being emplaced, d i f f e r e n t i a t i o n -101-was" t a k i n g place i n the main magma chamber. D i f f e r e n t i a t i o n i s shown by the modes of phases shown i n Tables I I to IV and i n Figure 31. P l a g i o c l a s e and b i o t i t e content remains f a i r l y uniform among phases but the composition of p l a g i o c l a s e i s l e s s c a l c i c towards the core of the b a t h o l i t h . There i s an increase i n amount of orth o c l a s e i n younger phases, but t h i s increase i s not r e g u l a r . Figure 31 shows that the Gump Lake and Witches Brook phases c o n t a i n the highest concentrations of o r t h o c l a s e . The spread of o r t h o c l a s e values f o r f i n e - g r a i n e d Witches Brook phase i s thought to represent a true range of or t h o c l a s e content w i t h i n the phase. The range of values i n the coarse-grained, p o r p h y r i t i c Gump Lake phase i n which o r t h o c l a s e occurs as la r g e ( > 1 M ) i r r e g u l a r l y spaced c l o t s , could be p a r t l y a r e s u l t of sampling e r r o r . The higher values obtained from stained slabs are b e l i e v e d most r e p r e s e n t a t i v e of the amounts of or t h o c l a s e i n t h i s phase and are probably a r e s u l t of d i f f e r e n t i a t i o n of magma. . Figure 31 shows an increase i n quartz i n younger phases and i s thought to be a r e s u l t of d i f f e r e n t i a t i o n . The wide range of values' f o r quartz content i n p o r p h y r i t i c Bethsaida phase may i n p a r t be due to sampling e r r o r . Hornblende content decreases t o -wards the core of the b a t h o l i t h . The v a r i a t i o n i n composition w i t h i n the Hybrid phase and the d i f f e r -ence i n average composition of t h i s and Highland V a l l e y phase i s probably not the r e s u l t of d i f f e r e n t i a t i o n but i s thought to be l a r g e l y the r e s u l t of contamination by w a l l r o c k . Thereby, phases a t the b a t h o l i t h margin •are r i c h e r i n hornblende, a u g i t e , magnetite and more C a - r i c h f e l d s p a r GRAPHIC REPRESENTATION OF MODES C O R E 8 0 -6 0 -ul < r-z L L ) (J or 2 0 -HYBRID GUICHON CHATAWAY L E ROY GUMP L A K E B E T H L E H E M WITCHES BR. B E T H S A I D A I F J I I PLAGIOCLASE I ^ I HORNBLENDE I 1 AN QUARTZ BIOTITE V/// / 4 RANGE E S T A B L I S H E D BY P O L I S H E D SLABS I E> | O R T H O C L A S E C F i g . 31: -103-than the c e n t r a l phases. During e a r l y stages of c r y s t a l l i z a t i o n of phases near the batho-l i t h margin, there may have been a. tendency f o r more b a s i c m a t e r i a l s to c r y s t a l l i z e f i r s t i n accordance w i t h the general order of c r y s t a l l i z a -t i o n of Bowen's r e a c t i o n s e r i e s (Bowen, 1956, p 60). C r y s t a l l i z a t i o n of b a s i c m a t e r i a l s a t the b a t h o l i t h margin by a process of d i f f u s i o n over short d i s t a n c e s , aided by convection, may have enriched the remaining magma i n more a c i d i c m a t e r i a l . A second form of d i f f e r e n t i a t i o n , to some extent, may have an oppos-i t e e f f e c t . There may be a tendency f o r v o l a t i l e s accompanied by a l k a l i s and s i l i c a to d i f f u s e upwards and outwards through the magma and concen-t r a t e w i t h i n the c r y s t a l l i n e inner edge of the b a t h o l i t h and i n cupolas. Kennedy (1955, p 490) has shown that v o l a t i l e s , i n an e f f o r t to reach uniform p a r t i a l pressures tend to d i f f u s e upwards and outwards to c o o l e r , lower pressure places i n the magma chamber. Walton (1955, pp 2-3) suggests that the p h y l l o s i l i c a t e and t e c t o s i l i c a t e s t r u c t u r e s which they form favour the c o o l e r , lower pressure areas. The o r t h o c l a s e - and q u a r t z - r i c h v a r i e t y of Witches Brook phase and l e u c o c r a t i c dykes and i r r e g u l a r bodies c u t t i n g o l d e r phases may be evidence of accumulation of such d i f f e r e n t i a t e d magma. I f the c o n f i n i n g pressure and s t r e n g t h of o v e r l y i n g rock i s exceeded the magma and i t s c o n c e n t r a t i o n of a l k a l i s , f o l l o wed by l e s s d i f f e r e n t i a t e d magma, break through the outer already c r y s t a l l i n e phases of the b a t h o l i t h . Upon f r a c t u r i n g , emplacement of alre a d y p a r t l y c r y s t a l l i n e magma i n c o o l e r e n c l o s i n g rock i s accompanied -104-by a decrease i n pressure and probable loss of v o l a t i l e s . The e f f e c t i s rapid c r y s t a l l i z a t i o n r e s u l t i n g i n fi n e g r a i n - s i z e . I t i s believed that such processes occurred during emplacement of the Bethlehem-Witches Brook phase. These processes account for the widespread occurr-ence of i r r e g u l a r dyke-like bodies of Witches Brook phase i n a l l older phases, for i t s great v a r i a t i o n s i n composition and i t s fine-grained s e r i a t e texture. Suggested History of Emplacement of the Guichon Creek B a t h o l i t h Mesozonal Environment The magma was emplaced to approximately the present l e v e l of the Guichon Creek b a t h o l i t h by a combination of magmatic stoping, a s s i m i l a -t i o n , d i f f e r e n t i a l g r a v i t a t i o n a l e f f e c t s between magma and country rocks and f o r c e f u l i n t r u s i o n by magmatic pressure. Depth of b u r i a l at t h i s stage would be 4 to 6 miles deep i n the mesozone. During t h i s period, much wallrock was dislodged and assimilated. Outward d i f f u s i o n of v o l a -t i l e s from the magma to marginal zones and inward d i f f u s i o n of v o l a t i l e s from country rock to the magma, possibly lowered the temperature of c r y s t a l l i z a t i o n and aided i n a s s i m i l a t i o n of basic m a t e r i a l . C r y s t a l l i -zation of the more basic components of the magma e f f e c t i v e l y l e f t the remaining magma more a c i d i c . A period of quiescence followed emplacement of the b a t h o l i t h during which c r y s t a l l i z a t i o n proceeded inwards from the margin gradually slowing as v o l a t i l e pressures began b u i l d i n g up, (Figure 32a). -105-(A) Mesozonal Environment (C)Epizonal Environment Figure 32 Diagrams showing the suggested sequence of events during emplacement of the Guichon Creek Batholith. i -106-The v o l a t i l e pressure f i n a l l y exceeded the c o n f i n i n g pressure and r e s u l t e d i n breakthrough of magma l o c a l l y to emplace the Highland V a l l e y phase i n the Hybrid phase and s t r a t i f i e d o l d e r r o c k s . There was l o c a l b r e c c i a t i o n and some a s s i m i l a t i o n of Hybrid and older rocks which r e -s u l t e d i n a gradation i n composition a t outer c o n t a c t s . A long p e r i o d of quiescence followed c r y s t a l l i z a t i o n of Highland V a l l e y phase (Guichon and Chataway v a r i e t i e s ) , during which there was again steady buildup of v o l a t i l e pressures and an accompanying slowing of c r y s t a l l i z a t i o n . C o n f i n i n g pressure and st r e n g t h of o v e r l y i n g rock was again exceeded causing f r a c t u r i n g i n c o o l e r c r y s t a l l i n e phases and emplacement of LeRoy g r a n o d i o r i t e as f i n e - g r a i n e d i r r e g u l a r d y k e - l i k e bodies. F r a c t u r i n g of coo l e r rock was accompanied by l o s s of pressure and v o l a t i l e s which r e -s u l t e d i n r a p i d c r y s t a l l i z a t i o n of an already p a r t l y c r y s t a l l i z e d magma. A f t e r emplacement of the Highland V a l l e y phase, the Gump Lake phase was emplaced on the east side of the b a t h o l i t h . I t s emplacement i s unexplained. A long quiescent p e r i o d allowed the maximum outward d i f f u s i o n of v o l a t i l e s which were accompanied-by a l k a l i s and s i l i c a . These m a t e r i a l s apparently c o l l e c t e d i n cupolas and apophyses along the inner c r y s t a l l -ine border of the b a t h o l i t h i c magma. V o l a t i l e pressure b u i l t up, p o s s i b l y accompanied by renewed magmatic pressure from below, u n t i l the c o n f i n i n g pressure was exceeded. Extensive f r a c t u r i n g of ol d e r c r y s t a -l l i n e phases occurred throughout the b a t h o l i t h . D i f f e r e n t i a t e d a l k a l i , quartz and metal-enriched magma of Witches Brook phase entered the -10.7-f r a c t u r e s i n country rock forming i r r e g u l a r d y k e - l i k e bodies and la r g e i r r e g u l a r masses. Loss of pressure and v o l a t i l e s caused r a p i d c r y s t a l l -i z a t i o n of the magma and r e s u l t e d i n a f i n e g r a i n - s i z e . Copper d e p o s i t s a s s o c i a t e d w i t h the Witches Brook phase were formed a t t h i s time. Mean-w h i l e , c r y s t a l l i z a t i o n of the Bethlehem phase occurred i n the main magma chamber. Bethlehem and Witches Brook phase and i t s v a r i e t i e s are prob-a b l y very c l o s e l y r e l a t e d and may be v a r i a t i o n s of one phase (Figure 32B). Ep i z o n a l Environment Emplacement and c r y s t a l l i z a t i o n of Hybrid, Highland V a l l e y and Bethlehem phases was accompanied by e r o s i o n of older rock o v e r l y i n g the b a t h o l i t h . Environment of emplacement of magma g r a d u a l l y changed from mesozonal c o n d i t i o n s to e p i z o n a l subvolcanic c o n d i t i o n s by the time the Bethlehem phase had c r y s t a l l i z e d . V o l a t i l e s and a s s o c i a t e d m a t e r i a l s again c o l l e c t e d a t the inner c r y s t a l l i n e margin. As v o l a t i l e pressure b u i l t up and l o c a l l y exceeded the c o n f i n i n g pressure, porphyry dyke swarms were emplaced and "pipe" b r e c c i a s were a l s o formed by e x p l o s i v e r e l e a s e of pressure. V o l a t i l e s and as s o c i a t e d m a t e r i a l s were deposited i n f r a c t u r e s i n outer c r y s t a l l i n e phases. These s o l u t i o n s were copper-r i c h and many more mineral d e p o s i t s such as Bethlehem Copper, Trojan and Krain,'. were formed a t t h i s time, accompanied by hydrothermal a l t e r a -t i o n . E r osion continued downwards; c r y s t a l l i z a t i o n of the Bethsaida phase occurred i n the main magma chamber. . V o l a t i l e s d i f f u s e d and there was buildup of vapour pressure. When the c o n f i n i n g pressure was again -108-exceeded, there was l o c a l emplacement of Bethsaida i n t o o l d e r phases. Outer c r y s t a l l i n e phases were at t h i s time c o o l i n g more r a p i d l y i n a shallower environment causing c h i l l i n g of Bethsaida a g a i n s t older phases. (Figure 32C). M i n e r a l d e p o s i t s such as O.K., Lornex and others a s s o c i a t e d w i t h Bethsaida phase, were formed a t t h i s time, poss-i b l y accompanied by emplacement of the Gnawed Mountain po r p h y r i e s . The l a s t d i f f e r e n t i a t e d magma to c r y s t a l l i z e formed a p l i t e and a l a s k i t e dykes and small i r r e g u l a r masses. Er o s i o n proceeded to the present l e v e l . Comparison of the Guichon Creek B a t h o l i t h to the S i e r r a Nevada B a t h o l i t h A comparison of the Guichon Creek b a t h o l i t h to the S i e r r a Nevada b a t h o l i t h i s of questionable value because of the great d i f f e r e n c e i n s i z e of areas of exposure and because of probable d i f f e r e n t l e v e l s of exposure. The Guichon Creek b a t h o l i t h i s exposed a t a high l e v e l j u s t below i t s r o o f . I f the i n t e r i o r p l a t e a u of B r i t i s h Columbia was s t r i p p e d of o v e r l y i n g s t r a t a to expose t h i s b a t h o l i t h to a deeper c r u s t a l l e v e l , probably more s i m i l a r i t i e s would become apparent between the Guichon and S i e r r a Nevada b a t h o l i t h s . Indeed, s i m i l a r r e l a t i o n s h i p s might be observed at depth between Guichon, N i c o l a , L y t t o n and Topley b a t h o l i t h s (and others p r e s e n t l y covered) as e x i s t between i n t r u s i o n s of the S i e r r a Nevada b a t h o l i t h , d escribed by Bateman & .Eaton (1967). -109-In s p i t e of d i f f e r e n c e s i n l e v e l s of exposure and s i z e of exposures there are s e v e r a l s t r i k i n g s i m i l a r i t i e s . Both b a t h o l i t h s arose from below as a magma or p a r t i a l melt. Both c o n s i s t of d i s t i n c t phases or i n t r u s i v e masses which are g e n e r a l l y i n sharp contact w i t h older phases. Phases can r e a d i l y be d i s t i n g u i s h e d by d i f f e r e n c e s i n texture and m i n e r a l composition. The r e l a t i v e age of phases or plutons can be d e t e r -mined from f i e l d r e l a t i o n s h i p s . Both b a t h o l i t h s range i n composition from quartz d i o r i t e to g r a n i t e but are predominantly g r a n o d i o r i t e or quartz monzonite (Bateman & Eaton, 1967, pp 1407-1417). Phases of the Guichon Creek b a t h o l i t h , although elongate i n a n o r t h -w e s t e r l y d i r e c t i o n p a r a l l e l to the s t r u c t u r a l g r a i n , i n general have a c o n c e n t r i c zonal arrangement becoming younger inwards. Plutons compris-i n g .the' S i e r r a Nevada b a t h o l i t h are a l s o elongate i n a n orthwesterly d i r e c t i o n but do not e x h i b i t a w e l l developed c o n c e n t r i c arrangement of i n t r u s i o n s and have a complex h i s t o r y of emplacement. The age of the Guichon Creek b a t h o l i t h i s l a t e T r i a s s i c to e a r l y J u r a s s i c . Emplace-ment of the S i e r r a Nevada b a t h o l i t h began w i t h the g r a n i t i c rocks along the east side of the b a t h o l i t h i n l a t e T r i a s s i c or e a r l y J u r a s s i c time. I n t r u s i o n s i n t o the west metamorphic b e l t have been dated as l a t e J u r a s s i c and plutons near the c r e s t of the S i e r r a Nevada are l a t e C r e t a -ceous (Bateman & Eaton, 1967, p 1409). I t i s p o s s i b l e that a deeper e r o s i o n l e v e l of the Guichon Creek b a t h o l i t h would r e v e a l s i m i l a r r e l a t -i o n s h i p s to nearby b a t h o l i t h s i n the i n t e r i o r p l a t e a u . V SUMMARY AND CONCLUSIONS The Guichon Creek b a t h o l i t h i s a semiconcordant, composite, upper mesozonal to ep i z o n a l i n t r u s i v e pluton c o n s i s t i n g of se v e r a l n e a r l y c o n c e n t r i c major phases. I t was emplaced as a c r y s t a l mush by a s e r i e s of magmatic pulses a f t e r Karnian time of Upper T r i a s s i c and before Middle J u r a s s i c . S t r a t i f i e d rocks of the Cache Creek group (Permian) and N i c o l a group (Karnian of Upper T r i a s s i c ) are intruded by the b a t h o l i t h . The northwest pa r t of the b a t h o l i t h i s unconformably o v e r l a i n by f o s s i l i -ferous marine s t r a t a of Middle J u r a s s i c . On the south and southwest sides of the b a t h o l i t h Lower Cretaceous, Spences Bridge v o l c a n i c rocks unconformably o v e r l i e the i n t r u s i v e rock. The northern p a r t of the b a t h o l i t h and the tops of many of the highest h i l l s i n the map-area are capped by T e r t i a r y v o l c a n i c r o c k s . Feeder dykes f o r these v o l c a n i c flows p i e r c e the b a t h o l i t h a t se v e r a l l o c a l i t i e s . Potassium-argon age determinations on b i o t i t e from fragmental rock of r h y o l i t i c composition gave ages of 49 - 3 my. and 51 _ 3 my. i n d i c a t i n g an Eocene age. Age determinations were not made of v o l c a n i c rock of other compositions o v e r l y i n g the b a t h o l i t h . The Guichon Creek b a t h o l i t h c o n s i s t s of seven major i n t r u s i v e phases. These phases are d i s t i n g u i s h e d on the b a s i s of t e x t u r a l v a r i a -t i o n , f i e l d r e l a t i o n and composition. R e l a t i v e age of contiguous phases was e s t a b l i s h e d by c r i t e r i a i n v o l v i n g dykes, contact b r e c c i a t i o n , xeno-l i t h s , and l e s s commonly, c h i l l e d c o n t a c t s . The v a r i o u s phases and v a r i e t i e s are summarized i n Table I . TABLE I : Phases and V a r i e t i e s of I n t r u s i v e Rock R e l a t i v e l y Old (1) Hybrid phase (2) Highland V a l l e y phases Guichon v a r i e t y Chataway v a r i e t y (3) LeRoy g r a n o d i o r i t e Intermediate (4) Gump Lake phase (5) Bethlehem phase (6) Witches Brook phase V a r i e t y A V a r i e t y B V a r i e t y C (7) Bethlehem Porphyries R e l a t i v e l y Young (8) Bethsaida phase quartz d i o r i t e , g r a n o d i o r i t e , quartz monzonite g r a n o d i o r i t e , : q u a r t z monzonite g r a n o d i o r i t e , quartz monzonite g r a n o d i o r i t e , quartz monzonite quartz monzonite g r a n o d i o r i t e , quartz monzonite g r a n o d i o r i t e g r a n o d i o r i t e g r a n o d i o r i t e , quartz monzonite, g r a n i t e g r a n o d i o r i t e , quartz monzonite. (9) Gnawed Mountain Po r p h y r i e s , younger Bethlehem Porphyries and a s s o c i a t e d i n t r u s i v e b r e c c i a s (10) L e u c o c r a t i c dykes and masses The Guichon Creek b a t h o l i t h shows both d i s c o r d a n t and concordant r e l a t i o n s h i p s to the older s t r a t i f i e d rock. Concordant r e l a t i o n s h i p s are suggested by s t r i k e of N i c o l a rock p a r a l l e l i n g and d i p p i n g away from the edge of the b a t h o l i t h on i t s west and east s i d e s . A concord-ant nature i s f u r t h e r suggested by the d i r e c t i o n of e l o n g a t i o n of the b a t h o l i t h p a r a l l e l i n g the general s t r u c t u r a l g r a i n of the country rock. -112-Elsewhere around the b a t h o l i t h margin dis c o r d a n t contact r e l a t i o n s h i p s are shown by t r u n c a t i o n of bedding by i n t r u s i v e rock, contact b r e c c i a -t i o n and dykes. A narrow aureole of a l b i t e - e p i d o t e h o r n f e l s , hornblende h o r n f e l s and epidote skarn i s developed a t the b a t h o l i t h margin. These meta-morphic f a c i e s suggest the older s t r a t i f i e d rock a t the b a t h o l i t h margin was heated no higher than about 550°C. On the ba s i s of i n t e r n a l and e x t e r n a l i n t r u s i v e contact r e l a t i o n -s h i p s , the narrow low grade metamorphic aureole i n r e l a t i v e l y f r e s h v o l c a n i c and sedimentary r o c k s , and f o l i a t i o n of mafic minerals and pre-f e r r e d o r i e n t a t i o n of p l a g i o c l a s e , the Guichon Creek b a t h o l i t h i s i n t e r -preted as a magmatic pluton r a t h e r than the r e s u l t . o f g r a n i t i z a t i o n . The b a t h o l i t h appears to have been emplaced by a combination of processes i n c l u d i n g magmatic s t o p i n g , a s s i m i l a t i o n of w a l l r o c k m a t e r i a l , and p o s s i b l y p a r t l y by f o r c e f u l i n t r u s i o n and e f f e c t of g r a v i t y on the magma as compared to denser country rock. X e n o l i t h s concentrated w i t h i n 1/4 mile of the b a t h o l i t h edge demon-s t r a t e that emplacement of magma took place p a r t l y by magmatic st o p i n g . They show various stages of r e c r y s t a l l i z a t i o n , metamorphism and.incorp-o r a t i o n i n t o magma. Some x e n o l i t h s have sharp contacts w i t h p l u t o n i c rock; others have i n d i s t i n c t margins and appear to be completely r e -c r y s t a l l i z e d and s t i l l others form f i n e - g r a i n e d m a f i c - r i c h c l o t s w i t h i n the i n t r u s i v e rock. Towards the margin of the b a t h o l i t h , p l u t o n i c rock, grades from un--113-contaminated g r a n o d i o r i t e and quartz d i o r i t e through p r o g r e s s i v e l y more contaminated rock showing wide t e x t u r a l and compositional v a r i a -t i o n s . At the contact w i t h older rock, contaminated i n t r u s i v e rock and r e c r y s t a l l i z e d o l d e r rock are d i f f i c u l t to d i s t i n g u i s h . The contaminated appearance of p l u t o n i c rock c l o s e to the b a t h o l i t h margin i s i n t e r p r e t e d as evidence of a s s i m i l a t i o n of p r e - b a t h o l i t h i c m a t e r i a l and not the r e s u l t of d i f f e r e n t i a t i o n w i t h i n the magma chamber. Walton (1955) suggests that g r a n i t i c magma can be emplaced by f l o a t -i n g upwards of the l i g h t e r and more mobile magma which can punch i t s way up through tens of thousands of f e e t of o v e r l y i n g s t r a t a w i t h s c a r c e l y n o t i c e a b l e s t r u c t u r a l d i s l o c a t i o n i n a manner s i m i l a r to the emplacement of s a l t domes. This process, too, may have played some r o l e i n emplace-ment of the Guichon Creek b a t h o l i t h . T e x t u r a l and compositional d i f f e r e n c e s and contact r e l a t i o n s h i p s between phases, suggest that the magma was emplaced as a p a r t l y c r y s t a l l -ine mush i n a s e r i e s of magmatic pu l s e s . Kennedy (1955) suggests that v o l a t i l e s i n a magma d i f f u s e upwards and outwards to regions of lower temperature and pressure i n order to eq u a l i z e the p a r t i a l v o l a t i l e pressure throughout the magma. This i s the e q u i l i b r i u m c o n d i t i o n . In doing so, the r e l a t i v e amount of H2O i s increased a t the margin and top of the chamber (Kennedy, 1955, p 445). I f the increase i n pressure • exceeds the c o n f i n i n g pressure and the stren g t h of the cap, f r a c t u r i n g or even a breakthrough occurs. Magma i s i n j e c t e d i n t o the r e s u l t i n g f r a c t u r e s . The supply and r a t e of d i f f u s i o n of v o l a t i l e s w i l l , to a -114-l a r g e extent, c o n t r o l the number and frequency of magmatic p u l s e s . • According Buddington's (1959) c r i t e r i a f o r environment of em-placement of b a t h o l i t h s , the older phases of the Guichon Creek b a t h o l i t h appear to have been emplaced under mesozonal c o n d i t i o n s , 4 to 6 mi l e s i n depth. Younger c e n t r a l phases were apparently emplaced i n a shallower e p i z o n a l environment. I t i s suggested that the environmental change could have been the r e s u l t of e r o s i o n of o v e r l y i n g m a t e r i a l during a long h i s t o r y of emplacement and c r y s t a l l i z a t i o n of successive phases of the b a t h o l i t h . The modes of phases and v a r i e t i e s i n d i c a t e d i f f e r e n t i a t i o n of magma from the margin to the core of the b a t h o l i t h . Two processes of d i f f e r -e n t i a t i o n appear to have been o p e r a t i v e . During e a r l y stages of c r y s t -a l l i z a t i o n of phases near the b a t h o l i t h margin, a form of d i f f e r e n t i a -t i o n of minor importance may have occurred. Basic m a t e r i a l s probably c r y s t a l l i z e d f i r s t i n accordance w i t h the general order of c r y s t a l l i z a -t i o n of Bowen's r e a c t i o n s e r i e s . As c r y s t a l l i z a t i o n progressed inwards, b a s i c m a t e r i a l s may have been e f f e c t i v e l y removed by d i f f u s i o n over short d i s t a n c e s , aided by convection, which enriched the remaining magma i n more a c i d i c m a t e r i a l . A second form of d i f f e r e n t i a t i o n has. somewhat the opposite e f f e c t ; that i s , a tendency i n c e r t a i n phases f o r a l k a l i s and s i l i c a to d i f f u s e outwards and upwards through the magma accompany-in g movement of v o l a t i l e s . There appears to have been periods during emplacement and c r y s t a l l i z a t i o n of the b a t h o l i t h i n which concentrations of a l k a l i s and s i l i c a occurred w i t h i n the c r y s t a l l i n e inner edge of the -115-b a t h o l i t h and i n cupolas below the c r y s t a l l i n e r o o f . F r a c t u r i n g r e -s u l t i n g from buildup of v o l a t i l e pressure exceeding c o n f i n i n g pressure, l e d to the formation of a l k a l i - and s i l i c a - r i c h , i r r e g u l a r d y k e - l i k e bodies i n older c r y s t a l l i z e d rock. G e o l o g i c a l evidence places the age of the Guichon Creek b a t h o l i t h w i t h i n l i m i t s of e a r l y Upper T r i a s s i c and Middle J u r a s s i c . Major phases can be placed i n approximate order of r e l a t i v e age on the b a s i s of geo l o g i c evidence. I t i s not p o s s i b l e , however, to d i f f e r e n t i a t e among va r i o u s phases on the b a s i s of K/A apparent ages because v a r i a t i o n s are w i t h i n a n a l y t i c a l l i m i t s ' o f u n c e r t a i n t y of the techniques used. No i n t e r v a l of time can be given f o r pe r i o d of emplacement of the b a t h o l i t h . I t can be s a i d , however, that: (1) most phases of the b a t h o l i t h were hot at approximately the same time. (2) b i o t i t e and hornblende of the major phases began r e t a i n i n g argon at approximately the same time, centered around 198 - 8 my. ago. (3) no s i g n i f i c a n t metamorphic' event has taken place i n t h i s area since that time. (4) emplacement of the b a t h o l i t h occurred a f t e r Karnian of Upper T r i a s s i c and w e l l before Middle J u r a s s i c . -116-BIBLIOGRAPHY A l d r i c h , L.T., Hart, S.R., W e t h e r i l l , G.W., Davis, G.L., T i l ton, G.R. and Doe, B., Radioactive Ages of Rocks, Carnegie I n s t . Wash. Year Book, 60, pp. 250-256, 1960/61. Baadsgaard, H., F o l i n s b e e , R.E. and Lipson, J . , Potassium-Argon Dates of B i o t i t e s from C o r d i l l e r a n G r a n i t e s , B u l l . Geol. Soc. Am. V o l . 72, pp. 689-702, 1961. Bateman, P.C. and Eaton, J.P., S i e r r a Nevada B a t h o l i t h , Science, V o l . 158, No. 3807, pp. 1407-1417, 1967. Bowen, N.L., The E v o l u t i o n of the Igneous Rocks, Dover P u b l i c a t i o n s Inc., 332 pp., 1956. Buddington, A.F., Granite Emplacement w i t h S p e c i a l Reference to North America, B u l l . Geol. Soc. Am. V o l . 70, pp. 671-747, 1959. Carr, J.M., P r e l i m i n a r y Notes of Some Rock Types Occurring on Bethlehem Property, Unpublished, B.C. Dept. of Mines, 1959. Carr, J.M., Po r p h y r i e s , B r e c c i a s and Copper M i n e r a l i z a t i o n i n the High-land V a l l e y , B.C., Canadian Mining Journal,Vol.81,pp.71-73,1960. Carr, J.M., Geology of the Promontory H i l l s , B.C. M i n i s t e r of Mines and Petroleum Resources Annual Report f o r 1960, pp.26-40, 1961. Carr, J.M., The Geology of P a r t of the Thompson R i v e r V a l l e y Between A s h c r o f t and Spences Bridge, B.C. M i n i s t e r of Mines and P e t r o l -eum Resources Annual Report f o r 1962, pp. 28-45, 1963. Cha p l i n , R.E., A P r e l i m i n a r y G e o l o g i c a l Survey of the Guichon Creek • B a t h o l i t h , South of Witches Brook, Unpublished B.A.Sc. Thesis, Dept. of Geol., Univ. of B.C., 1958. C o c k f i e l d , W.E., Geology and M i n e r a l Deposits of the N i c o l a Map-Area, Geol. Surv. Can., Mem. 249, 1948. Cooper, J.M., The Flame Photometric Determination of Potassium i n G e o l o g i c a l M a t e r i a l s Used f o r Potassium Argon Dating, Geochim. et Cosmochim. Acta, V o l . 27, pp. 525-546, 1963. Crickmay, C.H., J u r a s s i c Rocks of A s h c r o f t , B r i t i s h Columbia, Univ. of C a l i f o r n i a Pub.' B u l l , of G e o l . S c i . , Vol.19,No. 2, pp. 23-74, 1930. -117-C u r t i s , G.H., Evernden, J.F. and L i p s o n , J . , Age Determination of Some G r a n i t i c Rocks i n C a l i f o r n i a by the Potassium-Argon Method, C a l i f o r n i a D i v i s i o n of Mines, S p e c i a l Report 54, 1958. Dirom, G.E., Potassium-Argon Age Determinations on B i o t i t e s and Amphib-o l e s , Bethlehem Copper Property, B.C., M.Sc. Thesis, Unpublished, Department of Geophysics, Univ. of B.C., 1965; a l s o i n White e t a l , 1967. Drummond, A.D., M i n e r a l o g i c a l and Chemical Study of Craigmont Mine, M e r r i t t , B r i t i s h Columbia, Unpublished Ph.D. D i s s e r t a t i o n , Dept. of Geol., Univ. of C a l i f o r n i a , 1966. D u f f e l l , S. and McTaggart, K.C., A s h c r o f t Map-Area, B r i t i s h Columbia, Geol. Surv. Can., Mem. 262, 1952. Fol i n s b e e , R.E., Baadsgaard, H. and Lipson, J . , Potassium-Argon Time Scale, Rep. XXI, I n t . Geol. Congr., Norden, P t . I l l , pp. 7-17, 1960. F a r r a r , E., Macln t y r e , R.M., York, D. and Kenyon, W.J., A Simple Mass Spectrometer f o r the A n a l y s i s of Argon a t U l t r a - H i g h Vacuum, Nature, V o l . 204, No. 4958, pp. 531-533, 1964. H i l l s , L„ V. and Baadsgaard, H.s Potassium-Argon Dating of Some Lower T e r t i a r y S t r a t a i n B r i t i s h Columbia, B u l l . Canadian Pet. Geol., V o l . 15, No. 2, pp. 138-149, 1967. Hurley, P.M. e t a l , Standard B i o t i t e B-3203, N.Y.O. 3943, Tenth Ann. Prog. Rept., Dept. of Geol. Geophys., Mass. I n s t . Technol. p. 151, 1962. Johannsen, A., Petrography, V o l . 1, The U n i v e r s i t y of Chicago Press, pp. 318, 1939. Kennedy, G.C., Some Aspects of the Role of Water i n Rock M e l t s , i n Polder va.art, Crust of the Ea r t h , Geol. Soc. Am. S p e c i a l Paper 62, pp. 489-504, 1955. Kulp, J.L., G e o l o g i c a l Time Scale, Science, V o l . 133, No. 3459, pp. 1105-1114, 1961. Lanphere, M.A. and Dalrymple, G.B., Summary of A n a l y t i c a l Data, U.S. Geol. Survey Standard Muscovite P-207, Journ. Geophys. Research, V o l . 70, No. 14, pp. 3497-3503, 1965. Larsen, E.S., Time. Required f o r the C r y s t a l l i z a t i o n of the Great Batho-l i t h of Southern and Lower C a l i f o r n i a , Am. Jour. S c i . V o l . 243A, pp. 399-416, 1945. -L18-Leech, G . B . , Lowdon, J . A . . Stockwel l . C.H. and Wanless, R.K. , Age Determinations and Geological Studies, Geol . Surv. Can. , Paper 63-17. 1963. Lovering, T . S . , Temperature In and Near Intrusions, Econ. Geology F i f t i e t h Anniversary Volume, Econ. , Geology Pub. Co . , pp. 249-281. 1955. Lowdon, J . A . , Age Determinations and Geological Studies. Geol . Survey of Canada. Paper 62-17. P t . 1, p. 19, 1963. Mathews, W.H.. G l a c i a l Lakes and Ice Retreat i n South Central B r i t i s h Columbia, Trans. Royal Soc. Can. Sect. IV. pp. 39-57. 1944. Mathews, W.H., Thirteen Potassium Argon Dates of Cenozoic Volcanic Rocks from B r i t i s h Columbia. Univ. of B .C . . Dept. of G e o l . , Report No. 2. pp.16, 1963. Nockolds, S . R . , Some Theoret ical Aspects of Contamination i n Acid Magmas. Jour . Geol . V o l . XLI , No. 6. pp. 561-589. 1933. Par ry , J . R . , Invest igat ion of Spec i f i c Gravity i n G r a n i t i c Rocks, Unpublished B.A.Sc. Thes is , Dept. G e o l . , Univ. of B .C . . 1964. Rennie. C .C . , Copper Deposits i n the Nicola Rocks. Craigmont Mine, Western Miner and O i l Review. V o l . 35. No. 2. pp. 50-52, 1962. Van Der P l a s , L. and Tob i . A . C . , A Chart fo r Judging the R e l i a b i l i t y of Point Counting Resul ts , Am. Jour . S c i . , V o l . 263. pp. 87-90, 1965. Walton, M. , The Emplacement of Gran i te , Am. Jour . S c i . , V o l . 253, pp. 1-18. 1955. Wanless. R.K. . Stevens, R.D. , LaChance, G .R. . and Rimsaite, R .Y .H . , Age Determinations and Geological Studies, Geo l . Surv. Can. , Paper 64-17. P t . I. 1965. White, W.H.. Er ickson. G . P . , Northcote, K .E . . Dirom, G.E. and Harakal . J . E . . Isotopic Dating of the Guichon B a t h o l i t h , B .C . . Can. Jour . Earth Sciences, V o l . 4 . pp. 677-690. 1967. White, W.H., Thompson, R.M. and McTaggart, K .C . , The Geology and Mineral Deposits of the Highland V a l l e y , B .C . . C. I .M.M. T rans . , V o l . 60. pp. 273-289. 1957. Winkler , H.G.F. , Petrogenesis of Metamorphic Rocks. Springer-Verglag. New York. Inc . , pp. 220, 1965. -119-APPENDIX I GEOCHRONOLOGY A. Sampling Methods Representative samples weighing 50 to 100 pounds were c o l l e c t e d f o r each phase to be analysed. The sample-sites were chosen on the b a s i s of contact r e l a t i o n s h i p s , a c c e s s i b i l i t y and freshness of rock. Sample-sites are shown on Figure 6, Samples of ol d e r phases were taken as d i s t a n t as p o s s i b l e from contacts w i t h younger phases to minimize the danger of l o s s of argon from b i o t i t e . For the same reason near sur-face samples i n f o r e s t f i r e areas were avoided. Fresh rock was obtained by breaking through weathered, surfaces of outcrops w i t h a sledge hammer. Wherever p o s s i b l e , samples were taken from f r e s h c l i f f f a c e s , excava-t i o n s f o r power pylons and from road c u t s . The degree of a l t e r a t i o n of b i o t i t e was determined i n t h i n s e c t i o n s of the rock and by b i n o c u l a r m i c r o s c o p i c examination of b i o t i t e separates. A number of samples were disc a r d e d as too i n t e n s e l y a l t e r e d to give r e l i a b l e age determinations, B. B i o t i t e Separation The amount of sample necessary to give approximately 25 grams of - 1 2 0 -b i o t i t e was crushed to less than 1/2" diameter by using i n turn , a jaw crusher and core crusher. The crushed rock was then passed through a d isc pulver izer and sieved into four s ize f ract ions roughly the grain s i ze of the mafic minerals , -28 to +100 Tyler mesh, so that b i o t i t e would be released and a minimum of composite grains would remain. Each s i ze f r a c t i o n was washed i n a v e r t i c a l column water c l a s s i f i e r . For most samples a rough b i o t i t e concentrate could be made by the c l a s s i f i e r . The samples were dr ied by heating to less than 100°C under a heat lamp. Each washed and dr ied s ize f rac t ion was passed through an e l e c t r o s t a t i c separator (Dings Magnetic Separator, Company Model 2LAB) set to give a rough b i o t i t e concentrate. Magnetic grains were removed from concentrates wi th a hand magnet. Clean b i o t i t e concentrates were obtained by a com-b inat ion of add i t iona l processes inc luding heavy l i q u i d separation using bromoform, tetrabromoethane and diiodomethane, isodynamic (magnetic) separat ion, and by r o l l i n g the concentrate down paper towels, e l e c t r o -s t a t i c a l l y charged p l a s t i c sheets, and f i n a l l y , by hand p ick ing u n t i l an acceptable pur i ty was obtained. The p u r i f i e d b i o t i t e concentrates were washed several times with acetone to remove traces of heavy l i q u i d s . The f i n a l concentrates contain more than 95% b i o t i t e or c h l o r i t i z e d b i o t i t e . C h l o r i t i c a l t e r a t i o n i n b i o t i t e i s revealed by lower potassium va lues . Samples containing less than 4% potassium are considered un-r e l i a b l e for age determinations. - 1 2 1 -C. Potassium Analysis The potassium content of b i o t i t e was determined by flame photo-metric techniques using a Baird Atomic model KY-1 c l i n i c a l flame photo-meter which uses a l i th ium in te rna l standard. Results were recorded on a two-second response, 10 m i l l i v o l t , zero center Weston recorder connected i n ser ies with the photometer meter. Instrument i n s t a b i l i t y was reduced by use of propane as fue l and by i n s t a l l a t i o n of an external voltage regulator on the photometer power supply l i ne and by sens i t ive pressure regulat ing valves (G.E. Dirom, 1965, p 18). Care was taken to guard against contamination of samples and standard so lu t ions . Glassware was treated with S i l i c l a d at frequent in te rva l s and was soaked, af ter use, i n hot HNO3 and r insed i n pure water. D i s t i l l e d water, further p u r i f i e d by being passed through an ion exchange column, was used to r inse glassware and for making up to volume standard and b i o t i t e sample so lu t ions . Standard and b i o t i t e sample solu t ions were stored i n 1 l i t e r , a i r t i g h t , polyethylene b o t t l e s . Blanks, containing a l l chemicals and solut ions added to b i o t i t e sample solut ions run at in te rva ls during the analyses indicated that the l e v e l of potass-ium contamination was n e g l i g i b l e . B i o t i t e solut ions were prepared and analysed according to the pro-cedures described by Cooper (1963). Four samples weighing between 0.5 and 1.0 gms. were s p l i t from the stock concentrate. The second halves of the l a s t two s p l i t s were retained for argon analyses. B i o t i t e sample -122-were decomposed at temperatures less than 100°C i n a so lut ion of 3 ml concentrated H 2 S0 4 , 35 ml 49% HF and 2 ml of concentrated HNO3 f i n a l l y evaporated down to about 3 m l . The res idua l solut ions were brought up to exact ly 1000 ml with pure water and 100 ml of stock so lut ion conta in -ing 2000 ppm l i th ium and 5000 ppm sodium prepared from reagent grade L i C l and Na2S0^. The potassium content of b i o t i t e sample solut ions was determined by comparing unknown solut ions with standard solut ions con-ta in ing 200 ppm l i t h i u m , 500 ppm sodium, and an appropriate amount of potassium. Standard solut ions were prepared by d i sso l v ing weighed quant i t ies of dessicated, reagent grade K^SO^ i n pure water. One hundred ml of the same l i th ium and sodium stock so lut ion used to prepare the b i o t i t e sample solut ions was added to the standard so lut ion and was then made up to 1000 ml with pure water. Most b i o t i t e analyses were i n quad-r u p l i c a t e using d i f f e r e n t weights of b i o t i t e sample digested and analysed i n two completely separate runs. D. Argon Analyses Argon Extract ion and Measuring Equipment The argon ext ract ion and measuring system was designed by G . P . E r i c k -son, b u i l t and operated by Er ickson, ass is ted by J . E . Harakal . A b r ie f descr ip t ion i s given by White, et a l , 1967, p 683. Argon content of b i o t i t e was measured s t a t i c a l l y by a MS10 mass spectrometer (Associated E l e c t r i c a l Industr ies) which uses a 2 - i nch radiu -124-of curvature with 180° d e f l e c t i o n . The method of isotope d i l u t i o n was 38 used employing a known quantity of A as a tracer or spike and cor rec t -o r ion for contamination by atmospheric argon based on A concentration i n the gas sample. The same type of mass spectrometer i s successfu l l y being used i n the Geophysics Laboratory at the Univers i ty of Toronto. The operat ional c h a r a c t e r i s t i c s of the MS10 have been described by Farrar , e t a l , (1964). The procedures used at U.B.C. for fusion of b i o t i t e , 38 cleanup of argon, addi t ion of A sp ike, and introduct ion of the sample in to the mass spectrometer, are s imi la r to those used at the Univers i ty of Toronto in p r i n c i p l e , but d i f f e r i n procedure. Figure 32 i s a diagram of the argon ext ract ion and a n a l y t i c a l system used at U.B.C. (White, et a l , 1967, p 684). I t consists of four sect ions , fus ion sect ion , spike and a i r c a l i b r a t i o n sect ion , cleanup and i n l e t sect ion and a n a l y t i c a l sect ion (Figures 33, 34 and 35) . Each sect ion can be i so la ted from the other by u l t r a high vacuum metal va lves . Fusion and " c l e a n u p - i n l e t " sections are outgassed by mercury d i f f u s i o n and r o t -38 ary vacuum pumps. The a i r -A spike c a l i b r a t i o n sect ion i s outgassed by a rotary vacuum pump and the a n a l y t i c a l sect ion i s outgassed by an ion pump. Pressures i n a l l sections are monitored by p i r a n i gauges. An A reservo i r containing A ° of known pur i ty and a small volume 38 between two u l t r a high vacuum metal va lves , forms the A spike system. The amount of introduced by each spike i s determined by an a i r -a rgon c a l i b r a t i o n system (Figure 33) . The A 4^/A"^ r a t i o of atmospheric argon i s measured several times and amounts are calculated at S .T .P . Several Figure 34 MS10 Mass Spectrometer U.B.C, Geophysics Labora-t o r y and Professor G.P. E r i c k s o n Figure 37 MS10 Mass Spectrometer, U.B.C., Geophysics Lab-o r a t o r y , during f u s i o n of b i o t i t e sample. - 1 2 7 -more comparisons are then made of the amounts of atmospheric A and A 4 ^ and A^ 8 from each addit ion of sp ike. The amount of A"^8 "sp ike" i s 38 ca lcu lated at S .T .P . A ca l ib ra t ions were made at frequent in te rva l s between runs of unknown samples and a graph was prepared to show the 38 amount of A "sp ike" at S .T .P . released into the system by each a d d i t -ion of " s p i k e " . Immediately preceding each ana lys i s , a leak test of the argon l i n e was made by opening each section i n turn to the mass spectrometer and by observing the mass 40 and mass 28 s igna ls . Fusion of between 0.7 and 1.0 grams of sample i n an alundum-jacketed molybdenum cruc ib le i s accomplished by a 6 KW radio frequency generator and an induction c o i l which enc i rc les the fusion jar (Figure 33) . 38 A "sp ike" of A i s released into the fusion sect ion when the temperature of the sample reaches 1000°C during fus ion . A f i n a l temperature of about 1500°C, maintained for at least 10 minutes, was found to be s u f f i c i e n t to completely fuse the sample and release a l l argon. The pressure wi th in the fusion section was contro l led by lowering the temperature of the hot t i tanium sponge to absorb impuri t ies and by p lac ing dry ice on the cold f inger to remove H^O. During p u r i f i c a t i o n of argon samples, argon can be temporarily stored on charcoal at the temperature of l i q u i d n i t rogen, and the r e -maining gases pumped o f f . Impurit ies are adsorbed on t i tanium by cool ing the t itanium furnaces from 750°C and i n "cold f ingers" at the temperature of dry i c e . Any number of p u r i f i c a t i o n cycles could be car r ied out by -128 -a l te rna t ing the gas back and fo r th between fusion and "c leanup- int roduct -i o n " sect ions. Argon i s monitored into the mass spectrometer through a var iab le leak valve to give conveniently measurable s ignals of A , A and A , the A ^ s ignal being between 5 and 10 v o l t s . The average of 10 scans for both the 40/36 and 40/38 r a t i o s was used to determine the correct ion necessary for atmospheric argon i n the 40/38 r a t i o . Operational Character is t ics I t was found that the fusion section d id not require outgassing by baking i f outgassed for periods greater than twelve hours before making an ana lys i s . The mass spectrometer a n a l y t i c a l and c leanup - in le t sections were kept constantly at a high vacuum. I t was also found that there was no detectable memory e f fec t r e s u l t i n g from argon being adsorbed on tubing, metal va lves , e t c . and "bake-out" of th i s sect ion was unnecessary. S imi -l a r f indings are reported by York (1964) for the MS10 i n use at the Un ivers i ty of Toronto. Systematic changes i n observed r a t i o s during analyses were n e g l i g i b l y smal l , so that i t was not necessary to extrapolate the r a t i o s to time of admission to the mass spectrometer. For each analys is a check was made to determine the f r a c t i o n of the t o t a l quantity of gas ac tua l l y admitted to the spectrometer so that f r a c t -ionat ion e f fec ts at the leak valve could be evaluated. The small volume between V5 and V 5 , (Figure 33) approximately 10% of the volume of the p u r i f i c a t i o n - i n l e t sect ion , was used for that purpose. In a l l analyses - 1 2 9 -l e s s than 10% of the t o t a l volume of gas was used. For b i o t i t e 200 my o l d 0.7 to 1.0 gm of sample gives more than adequate argon f o r measure-ment by the MS10. Cor r e c t i o n s f o r f r a c t i o n a t i o n a t the valve and f o r d i s c r i m i n a t i o n i n the mass spectrometer, were made on the measured A4^/A"^ and A 4 * " V A ^ 8 r a t i o s . These c o r r e c t e d values were used i n age c a l c u l a t i o n s . P r e c i s i o n and Accuracy Du p l i c a t e and r e p l i c a t e analyses that have been made of samples from the Guichon Creek b a t h o l i t h and i n t e r - l a b o r a t o r y standard samples give a measure of p r e c i s i o n f o r both potassium and argon analyses a t the U.B.C. K/A age-dating l a b o r a t o r y . These data are l i s t e d on Tables X I I to XV. The average p r e c i s i o n of potassium analyses i s 0.78% and of argon 4 0 rad. i s 1.04% (Tables X I I and X I I I ) . Accuracy i s estimated from i n t e r - l a b o r a t o r y comparisons of analyses of the same m a t e r i a l . U.B.C. r e s u l t s f o r K and A on three i n t e r - l a b o r a t o r y standard micas are compared w i t h those of other l a b o r a t o r i e s on Tables XI and X I I . Accuracy of U.B.C. potassium analyses are w i t h i n t 17o. Accur-acy of U.B.C. argon analyses are w i t h i n approximately 37». The l i m i t s of e r r o r are therefore set a t ~t 4% of the c a l c u l a t e d age f o r samples c o n t a i n -i n g l e s s than 507.. atmospheric argon. -130-TABLE X I I : K Analyses P r e c i s i o n Sample Number . No. of I n t e r - l a b o r a t o r y standards Analyses X S 7, GE2060 22 6.81%K 0.10 1.467, P207 5 8.61 0.04 0.467o Guichon B a t h o l i t h samples K63-13 4 4.49 0.02 0.457o K63-156a 6 6.73 . 0.01 0.157o K63-223 4 5.77 0.02 0.357, K64-116a 4 5.24 0.04 0.767, K63-220 4 5.20 0.02 0.387, K63-37 4 6.42 0.03 0.487, K64-98-I 4 ' 5.95 0.01 0.177, K63-115 '4 5.90 0.07 1.197, K64-186a 4 • 1.87 0.01 . 0.537, K64-102 4 4.91 0.03 0.617, • K64-101 4 5.16 .. 0.05 0.977, K64-105-I 4 6.53 0.04 . 0.617, K63-171 4 6.59 0.06 0.917, K64-203 4 4.42 0.02 0.457, K64-171 4 3.59 0.02 0.567, K63-187 4 4.48 0.02 0.477, K63-231 4 5.86 0.07 1.197, K Analyses weighted average of p r e c i s i o n = 0.787, Constants used i n c a l c u l a t i o n of r a d i o g e n i c ages (K/A Method): = 0.58 x 1 0 " 1 0 y r " 1 = 4.72 x 1 0 " 1 0 y r " 1 4 0 K / V = 1.181 x 10 -131-TABLE X I I I : Argon P r e c i s i o n Sample Number No. of Samples 40 J  Ar r ad Ar t o t a l 40 J Ar,. rad ( l O x c STP/g) I n t e r - l a b o r a t o r y standards P207 Muscovite (6) X DM 2.779 2.806 2.855 2.787 2.745 2.826 = 2.800 0.029 + - 1.04% G.E. 2060 B i o t i t e (3) X DM 5.484 5.438 5.423 = 5.448 ± 0.027 0.49% Guichon B a t h o l i t h K63-13 (2) 3.795 3.716 X = 3.755 DM t 0.04 = t 1.07% K64-156a (2) 5.785 5.659 X = 5.722 DM + 0.063 = t 1.10% K63-220 (2) 4.358 : 4.325 X = 4.341 DM + 0.017 = 1 0.39% K63-37 (2) 5.390 5.385 X = 5.387 DM t 0.003 + 0.06% -132-TABLE XIII: Argon P r e c i s i o n - cont'd Sample Number K64-98-I K63-115 No. of Samples (2) (2) A r 4 0 r a d Ar r * d Ar t o t a l (10 _ 5cc STP/g) 4.817 4.919 X = 4.868 DM t 0.051 4.307 4.788 X = 4.547 DM t 0.240 t 1.05% t 5.28% K64-102 K64-105-I (2) .• (2) 4.055 4.077 X = 4.066 DM 1" 0.011 5.442 ,5.536 X = 5.489 DM 1" 0.047 + 0.27% + 0.86% K64-203 K63-187 K63-114 (2) (2) (2) + 0.14% 3.759 3.750 X .= 3.754 DM t 0.005 3.590 3.648 X = 3.669 DM £ 0.021 1.389 1.433 X = 1.411 DM t 0.022 = t 1.56% + 0.57% Weighted D.M. t 1.04% -133-TABLE XIV: . I n t e r - L a b o r a t o r y R e s u l t s A 4 0 r a d A 4 0 r a d Standard No. Laboratory M i n e r a l A n a l y s t GE 2060 B i o t i t e Columbia E r i c k s o n , G.P, McDowell, F. Yale Armstrong, D. U.B.C. 'Northcote, Dirom, White, Harakal (20) 6.92% I 6.91% I 6.89% P 6.81% P 6.82% P Potassium T o t a l A 4 0 ( i n 10 "'ccSTP/g) 0.97 0.90 X 6.87% 6.81%-t 0.10 0.95 0.63. 0.83 0.48 K - U.B.C. d i f f e r s from Mean value of other labs by -0.06 A - U.B.C. d i f f e r s from Mean value of other labs by 5.579 _ 5.628 X 5.603 5.484 5.438 5.423 _ 5.394 X 5.435 0.87% 2.99% P 207 Muscovite Lanphere & Dalrymple 1965 U.B.C. Northcote, Dirom, Harakal 8.58%-t 0.12 8.61% t 0.04 0.77 0.90 0.66 2.840 t .063 2.742 2.666 2.722 X 2.710 K - U.B.C. d i f f e r s from Mean value of other labs by +0.03 or + 0.35% A - U.B.C. d i f f e r s from Mean value of other labs by , - 4.57% B 3203 B i o t i t e Summary, Hurley e t a l , 1962 U.B.C. Harakal, J.E. 0.72 U.B.C. d i f f e r s from Mean value of o t h e n l a b s by 38.77 t 0.14 38.37 1.03% -134-TABLE XV: Summary of Accuracy of Potassium and Argon Analyses U.B.C. values w i t h i n .62% (weighted average), U.B.C. values w i t h 3.10% (weighted average) of average values obtained from other l a b o r a t o r i e s . -135-E. D e s c r i p t i o n of B i o t i t e used f o r K / A Age Determinations K64-102 Witches Brook phase P u r i t y : greater than 95% b i o t i t e and c h l o r i t e w i t h l e s s than 15% c h l o r i t i c a l t e r a t i o n . C olor: l i g h t brown/black, many g r a i n s mottled by s i l v e r y to l i g h t s i l v e r y green, c h l o r i t i c a l t e r a t i o n . I m p u r i t i e s : l e s s than 15% c h l o r i t e , s c a t t e r e d g r a i n s of b i o t i t e p o i k i l i t i c a l l y e n c l o s i n g quartz and f e l d s p a r ( p l a g i o c l a s e ) . Few s c a t t e r e d g r a i n s of amphibole, hornblende and l i g h t green a c t i n o l i t e ? Trace of i r o n oxide cementing s e v e r a l g r a i n s (quartz) together. K63-171 Witches Brook "A" phase , P u r i t y : 98% b i o t i t e and c h l o r i t e w i t h l e s s than 5% c h l o r i t i c a l t e r a t i o n . C olor: mottled black and l i g h t golden brown, s e v e r a l g r a i n s show-in g s i l v e r y green, c h l o r i t i c a l t e r a t i o n . I m p u r i t i e s : . l e s s than 5% c h l o r i t e , few g r a i n s of b i o t i t e p o i k i l i t -i c a l l y e n c l o s i n g p l a g i o c l a s e . Trace of i r o n - s t a i n e d g r a i n s presumably o x i d i z e d magnetite. K 6 4 - l l 6 a Chataway v a r i e t y P u r i t y : greater than 95% b i o t i t e and c h l o r i t e w i t h l e s s than 10% c h l o r i t i c a l t e r a t i o n . C olor: b l a c k , mottled by golden brown, s c a t t e r e d g r a i n s s i l v e r y green, c h l o r i t i c a l t e r a t i o n . K63-223 Guichon v a r i e t y P u r i t y : f r e s h , approximately 957, pure b i o t i t e , l e s s than 57« c h l o r -i t i c a l t e r a t i o n . C olor: dark golden brown/black, resinous l u s t e r w i t h a few g r a i n s of s i l v e r y green. -136-I m p u r i t i e s : few s c a t t e r e d g r a i n s of c h l o r i t i c a l t e r a t i o n , trace of f e l d s p a r g r a i n s . K64-203 Witches Brook phase P u r i t y : approximately 98% b i o t i t e and c h l o r i t e , 15% c h l o r i t i c a l t e r a t i o n . Color: medium to dark brown, many g r a i n s showing s i l v e r y green a l t e r a t i o n . I m p u r i t i e s : few g r a i n s of quartz and f e l d s p a r , 15% c h l o r i t i c a l t e r a -t i o n . K63-220 LeRoy " g r a n o d i o r i t e " P u r i t y : greater than 95% b i o t i t e and c h l o r i t e w i t h about 107, show-ing c h l o r i t i c a l t e r a t i o n . Color: dark brown-grey, medium golden brown, s c a t t e r e d g r a i n s show m o t t l i n g w i t h s i l v e r y green. I m p u r i t i e s : approximately 107o of the b i o t i t e shows c h l o r i t i c a l t e r a -t i o n . Scattered p o i k i l i t i c hornblende c r y s t a l s l e s s than 5%. K63-115 Bethlehem phase •N P u r i t y : approximately 957<, b i o t i t e and c h l o r i t e , approximately 157„ c h l o r i t i c a l t e r a t i o n . C olor: b l a c k , mottled by golden brown and mottled by s i l v e r y ,. green, c h l o r i t i c a l t e r a t i o n . I m p u r i t i e s : 15%, c h l o r i t e , l e s s than 57, hornblende, tra c e a c t i n o l i t e , few s c a t t e r e d g r a i n s of p l a g i o c l a s e f e l d s p a r and q u a r t z , trace of epidote. K63-231 Bethsaida phase P u r i t y : approximately 957, b i o t i t e and c h l o r i t e , of which 10 to 157a i s c h l o r i t e . -137-Color: dark golden brown and b l a c k , s i l v e r y green, c h l o r i t e g r a i n s . I m p u r i t i e s : 10 to 15% c h l o r i t e i n separate g r a i n s , trace of horn-blende, s c a t t e r e d g r a i n s of p l a g i o c l a s e f e l d s p a r and quartz, some forming composite gr a i n s w i t h b i o t i t e . K63-13 Hybrid phase P u r i t y : approximately 95% b i o t i t e showing c h l o r i t i c a l t e r a t i o n . C olor: dark brown-grey, golden brown and black mottled by l i g h t brown and l i g h t s i l v e r y brown. I m p u r i t i e s : abundant l i g h t s i l v e r y brown, c h l o r i t i c a l t e r a t i o n , l e s s than 5%, composite gr a i n s of quartz, p l a g i o c l a s e and hornblende. K64-101 LeRoy " g r a n o d i o r i t e " P u r i t y : greater than 95% b i o t i t e and c h l o r i t i c b i o t i t e . C olor: black and dark grey-brown, mottled by l i g h t golden brown. Abundant l i g h t s i l v e r y tan mottled g r a i n s . I m p u r i t i e s ; abundant c h l o r i t e represented by l i g h t s i l v e r y tan and l i g h t s i l v e r y brown g r a i n s . Less than 5% composite g r a i n s of p l a g i o c l a s e , quartz and hornblende. K63-187 Bethsaida phase P u r i t y : greater than 95% c h l o r i t i c b i o t i t e , approximately 30%, c h l o r i t i c a l t e r a t i o n . Color: dark brown-grey, mottled by golden brown and by l i g h t , s i l v e r y green, c h l o r i t i c a l t e r a t i o n . I m p u r i t i e s : approximately 30% c h l o r i t e . Few composite g r a i n s of of c h l o r i t i c b i o t i t e , q u a rtz, p l a g i o c l a s e and b o r n i t e . -138-K64-98-I Gump Lake phase P u r i t y : approximately 98% c h l o r i t i z e d b i o t i t e c o n t a i n i n g l e s s than 10% c h l o r i t e . C o l o r : dark brown-grey to bl a c k , mottled by l i g h t golden brown and tan. S l i g h t m o t t l i n g by l i g h t s i l v e r y green/tan. I m p u r i t i e s : few g r a i n s of c h l o r i t e , s c a t t e r e d g r a i n s showing obvious c h l o r i t i c a l t e r a t i o n . Few g r a i n s of b i o t i t e p o i k i l i t i c a l l y e n c l o s i n g p l a g i o c l a s e . K63-37 LeRoy " g r a n o d i o r i t e " P u r i t y : approximately 98% s l i g h t l y c h l o r i t i z e d b i o t i t e showing approximately 5% c h l o r i t i c a l t e r a t i o n . Color: black, g l i s t e n i n g , l i g h t e r golden brown on t h i n f l a k e s . I m p u r i t i e s : approximately 5%, c h l o r i t e , l e s s than 2% s c a t t e r e d g r a i n s of hornblende. Trace of sphene, trace of b i o t i t e g r a i n s p o i k i l i t i c a l l y e n c l o s i n g p l a g i o c l a s e . K64-186a Bethlehem phase P u r i t y : greater than 50% c h l o r i t i c a l t e r a t i o n . C olor: medium to dark grey-brown, extensive m o t t l i n g by tan and s i l v e r y green. I m p u r i t i e s : greater than 50% c h l o r i t i c a l t e r a t i o n , l e s s than 5%, s c a t t e r e d g r a i n s of hornblende, composite g r a i n s of q u a r t z , p l a g i o c l a s e , hornblende, trace of sphene. K64-156a Hybrid phase P u r i t y : greater than 95% unaltered b i o t i t e . C o l o r : black and dark golden brown, medium to l i g h t golden brown, on thinner f l a k e s , r esinous l u s t e r . I m p u r i t i e s : s c a t t e r e d composite g r a i n s c o n t a i n i n g hornblende, quartz and p l a g i o c l a s e . -139-K64-105-I Witches Brook phase P u r i t y : greater than 957» c h l o r i t i z e d b i o t i t e showing l e s s than 107. a l t e r a t i o n . . C o l o r : b l a c k , dark brown-grey, mottled by golden brown on t h i n edges. I m p u r i t i e s : l e s s than 107» c h l o r i t i c a l t e r a t i o n , s c a t t e r e d g r a i n s of amphibole (hornblende?), s c a t t e r e d composite g r a i n s c o n t a i n i n g quartz, p l a g i o c l a s e . -140-APPENDIX II DESCRIPTION OF ROCK SPECIMENS AND THIN SECTIONS 1. K63-230 V Hornfels, ( s i l i c i f i e d and p y r i t i z e d lava), Ashcroft Macroscopic: Medium grey with s l i g h t smoky blue t i n t , very fine-grained to m i c r o c r y s t a l l i n e , cherty appearance, few scattered fine-grained phenocrysts (or fragments?), otherwise massive, hard, b r i t t l e , con-choidal f r a c t u r e . Abundantly disseminated very fine-grained p y r i t e , Orange-brown iron-oxide s t a i n i n g . Microscopic: G r a i n - s i z e * Quartz 50-220 microns Plagioclase 80-350 " B i o t i t e 80-200 " Pyri t e 50-320 " Magnetite) . C h l o r i t e ) Epidote ' ' Texture: Paving block texture, anhedral quartz and feldspar grains, widely scattered b i o t i t e showing c h l o r i t i c a l t e r a t i o n and shredded appearance. L i t t l e or no cementing ma t e r i a l . Contains minute stringers of s l i g h t l y coarser quartz and feldspar grains. 2. K63-119 Hornfels, ( s i l i c i f i e d v o l c a nic b r e c c i a ) , Ashcroft. Macroscopic: Grain-size . Matrix: Quartz 35 microns Plagioclase 35 " B i o t i t e 35 '•" Epidote C a l c i t e C h l o r i t e Opaque * Grain-size measurements should not be taken l i t e r a l l y . They show merely the range i n size of sections through a number of grains of a given mineral. Any measurement i n th i n section would only f o r t u i t o u s l y be i n the plane of greatest length of a grain. -141-Phenocrysts: P l a g i o c l a s e (epidote and s e r i c i t e a l t e r a t i o n ) 360 microns Fragments: F e l d s p a t h i c , very f i n e g r a n u l a r , clouded by a l t e r a t i o n and minute opaque g r a i n s . Texture: Fragmental, p o r p h y r i t i c , m a t r i x i s very f i n e g r a n u l a r , g r a i n s are subrounded anhedral, r e c r y s t a l l i z e d ( ? ) . Phenocrysts are almost completely s e r i c i t i z e d . 3. K63-119 I I I H o r n f e l s , A s h c r o f t Macroscopic: M o t t l e d l i g h t and medium green-grey and tan, m i c r o c r y s t a l l -ine to cherty appearance, w i d e l y s c a t t e r e d f i n e - g r a i n e d p l a g i o c l a s e phenocrysts (?) s c a t t e r e d aggregates of green m a f i c , dense, hard, tough. Trace of disseminated p y r i t e and p y r i t e i n minute f r a c t u r e s , M i c r o s c o p i c : G r a i n - s i z e M a t r i x : Quartz 70 microns F e l d s p a t h i c g r a i n s 70 " A p a t i t e Z i r c o n (?) ' C a l c i t e Epidote C h l o r i t e Opaque Phenocrysts: P l a g i o c l a s e 300 microns to 2.3 mm. Texture: M a t r i x quartz and f e l d s p a t h i c g r a i n s , anhedral, i r r e g u l a r i n t e r -l o c k i n g , disseminated i r r e g u l a r blebs of c a l c i t e and c h l o r i t e w i t h w i d e l y disseminated f l e c k s of c h l o r i t i z e d b i o t i t e . 4. K63-119 V H o r n f e l s ( s i l i c i f i e d p o r p h y r i t i c v o l c a n i c ? ) , A s h c r o f t Macroscopic: M o t t l e d cream and tan, l i g h t greenish t i n t , m i c r o c r y s t a l l -ine to c h e r t y appearance, w i d e l y s c a t t e r e d f i n e - g r a i n e d p l a g i o c l a s e phenocrysts, w i d e l y s c a t t e r e d aggregates of green m a f i c , dense, hard, tough. -142-M i c r o s c o p i c : M a t r i x : Quartz F e l d s p a t h i c g r a i n s Epidote aggregates C h l o r i t e C a l c i t e G r a i n - s i z e 30-60 microns 90-150 " Phenocrysts: P l a g i o c l a s e ( r e l i e f l e s s than quartz) 1.8 to 0.60 mm. Texture: M a t r i x of equigranular anhedral i n t e r l o c k i n g g r a i n s of quartz and f e l d s p a t h i c m a t e r i a l . Cut by minute v e i n l e t s of s l i g h t l y coarser quartz 1 to 2 g r a i n s wide. Widely s c a t t e r e d subhedral/euhed-r a l f e l d s p a r phenocrysts. 5. K63-74 P r e - i n t r u s i v e P o r p h y r i t i c Lava, A s h c r o f t ( s l i g h t l y s i l i c i f i e d ) Macroscopic: Dark grey-green, a p h a n i t i c groundmass, s c a t t e r e d phenocrysts f e l d s p a r l e s s than 1 to 3 mm w i t h no p r e f e r r e d o r i e n t a t i o n , s c a t t e r e d c h l o r i t i z e d mafic c l o t s , disseminated very f i n e - g r a i n e d aggregates of epidote l e s s than 1 to 2 mm w i t h epidote present on f r a c t u r e sur-fa c e s . The disseminated epidote i s i n t i m a t e l y a s s o c i a t e d w i t h f e l d s -par phenocrysts and may be the r e s u l t of a l b i t i z a t i o n of c a l c i c f e l d s p a r s . Traces of disseminated p y r i t e . M i c r o s c o p i c : M a t r i x : F e l d s p a t h i c g r a i n s Quartz Phenocrysts: 2% P l a g i o c l a s e Epidote ) C h l o r i t e ) C a l c i t e ) G r a i n - s i z e 15 x 55 microns 80 microns 1.2 mm to 0,6 mm An 32 ? euhedral clouded by a l t e r a t i o n a l t e r a t i o n products a s s o c i a t e d w i t h phenocrysts Texture: P o r p h y r i t i c , f e l t e d f e l d s p a t h i c groundmass w i t h quartz pheno-c r y s t s of p l a g i o c l a s e as i s o l a t e d c r y s t a l s and c l u s t e r s of f i n e r g r a i n s , corroded borders, i n t i m a t e l y a s s o c i a t e d w i t h and " r e p l a c e d " by epidote, c h l o r i t e and c a l c i t e . K63-90-I P r e - i n t r u s i v e Greenstone ( B r e c c i a ) , A s h c r o f t Macroscopic: Dark green-grey, a p h a n i t i c w i t h widely disseminated fragments or aggregates of c r y s t a l g r a i n s 1 - 2 mm diameter, cut by minute -143-e p i d o t e - f i l l e d v e i n l e t s . Otherwise massive, dense. Dark brown and orange-brown i r o n s t a i n i n g . M i c r o s c o p i c : G r a i n - s i z e M a t r i x : F e l d s p a t h i c g r a i n s 30 x 160 microns Quartz Rock fragments: s e r i c i t i z e d , P l a g i o c l a s e 150 x 560 to 320 x 480 microns e p i d o t i z e d A ugite) aggregates Quartz) Epidote Magnetite) P y r i t e ) 15 microns Texture: Fragmental. S l i g h t l y p o r p h y r i t i c , f e l t e d groundmass of minute f e l d s p a r l a t h s and quartz g r a i n s c o n t a i n i n g s c a t t e r e d coarse-grained rock fragments. Cut by t h i n epidote and quartz s t r i n g e r s . 7. K63-90 V B a s a l t (feeder dyke), A s h c r o f t Macroscopic: Dark brown-grey, buff on s p l i n t e r edges, very f i n e - g r a i n e d to a p h a n i t i c , weathers l i g h t brown, contains s c a t t e r e d f i n e - g r a i n e d phenocrysts, dense. M i c r o s c o p i c : M a t r i x : P l a g i o c l a s e c r y s t a l l i t e s A n ^ Magnetite Indeterminable i n t e r s t i t i a l m a t e r i a l Phenocrysts: Augite 10%, s i z e ranges from c r y s t a l l i t e s to s e v e r a l times l a r g e r Texture: T r a c h y t i c groundmass, s l i g h t l y p o r p h y r i t i c . The rock i s f r e s h showing l i t t l e a l t e r a t i o n . Traces of carbonate as v e i n l e t s . 8. K63-89-I P o r p h y r i t i c B r e c c i a , A s h c r o f t Macroscopic: Mot t l e d medium green-grey, l i g h t grey, o l i v e green, green-i s h tan, p o r p h y r i t i c w i t h i r r e g u l a r fragments of tan porphyry w i t h widely s c a t t e r e d phenocrysts. D i f f i c u l t to d i s t i n g u i s h fragments from m a t r i x . Scattered i r r e g u l a r masses of b l a c k m a t e r i a l , dense. 144-M i c r o s c o p i c : G r a i n - s i z e Groundmass F e l d s p a t h i c m a t e r i a l ) l e s s than 10 microns to 100 microns Quartz ) Phenocrysts P l a g i o c l a s e 15% 3.15 mm i n s i z e subhedral, corroded Quartz 0.5 mm subhedral Epidote 0.32 x 0.08 to 0.24 x 0.05 mm aggregates of g r a i n s Texture: Fragmental. P o r p h y r i t i c fragments: p l a g i o c l a s e , quartz pheno-c r y s t s and aggregates of epidote g r a i n s i n a m i c r o c r y s t a l l i n e f e l d -spar and quartz m a t r i x . 9. K63-88a I I Greenstone B r e c c i a , A s h c r o f t Macroscopic: Dark grey, mottled by i r r e g u l a r fragments of medium green, i r r e g u l a r o u t l i n e . Dense, b r i t t l e , brown i r o n s t a i n i n g . M i c r o s c o p i c : Fragments - some weakly p o r p h y r i t i c (a) Feldspar g r a i n s extensive cloudy a l t e r a t i o n Quartz Epidote s c a t t e r e d g r a i n s Magnetite abundant P y r i t e (b) Pyroxene r i c h fragments , e x t e n s i v e l y a l t e r e d to b l a c k masses, cloudy (c) Epidote? r i c h fragments aggregates of very small granules cloudy appearance Magnetite M a t r i x - s l i g h t l y coarser grained F e l d s p a t h i c m a t e r i a l )uartz ^agnetite Indeterminable " d u s t - l i k e " m a t e r i a l between g r a i n s Texture: B r e c c i a composed of e x t e n s i v e l y a l t e r e d greenstone fragments which are weakly p o r p h y r i t i c , s i l i c i f i e d by l a t e q u a r t z . -145-10. K64-11-IV Epidote Skarn ( B r e c c i a ) , Basque Macroscopic: Mottled shades of o l i v e green, dark grey/black, medium grey and blue-green, fragments l e s s than one-haIf i n c h diameter, w i t h " c h e r t y " appearance. M a t r i x very f i n e - g r a i n e d , e p i d o t e - r i c h m a t e r i a l , cherty appearance w i t h traces of coarser epidote g r a i n s and disseminated p y r i t e . M i c r o s c o p i c : M a t r i x - mixture of a l t e r e d f e l d s p a t h i c m a t e r i a l , quartz w i t h e p i -dote g r a i n s . Fine granular cloudy a l t e r a t i o n product pseudomorphous a f t e r amphibole? . C h l o r i t i c fragments Fragments - epidote? aggregates of very f i n e y e l l o w g r a i n s w i t h cloudy f e l d s p a t h i c m a t e r i a l A l t e r e d p o r p h y r i t i c fragments Texture: B r e c c i a of p o r p h y r i t i c fragments i n a q u a r t z - r i c h f e l d s p a t h i c m a t r i x . Extensive epidote and c h l o r i t i c a l t e r a t i o n . S i l i c i f i e d . 11. K64-20-I Hornfels (contact r o c k ) , Basque Macroscopic: Layered, l i g h t tan-grey, s l i g h t b l u i s h t i n t and s c a t t e r e d m o t t l i n g o l i v e green epidote and greenish b l u e . "Cherty" t e x t u r e , i n t e r r u p t e d by i r r e g u l a r m a f i c - r i c h p a r t i n g s . Dense, subconchoidal f r a c t u r e . M i c r o s c o p i c : Very f i n e - g r a i n e d / m i c r o c r y s t a l l i n e aggregates of quartz and f e l d s p a t h i c m a t e r i a l . Scattered g r a i n s of coarser grained quartz p o r p h y r o b l a s t s . Patches r i c h i n aggregates of epidote g r a i n s . Scattered c l u s t e r s of c h l o r i t i z e d b i o t i t e g r a i n s w i t h a s s o c i a t e d magnetite f l e c k s . Cut by minute veins of epidote and quartz v e i n s or i r r e g u l a r coarser i r r e g u l a r l e n s e s . 12. K63-92a Greenstone B r e c c i a , Basque Macroscopic: Subrounded fragments of s p a r s e l y p o r p h y r i t i c greenstone, l i g h t cream-green and medium green i n a very f i n e fragmental m a t r i x of the same m a t e r i a l but showing abundant c l o t s of aggregates of epidote g r a i n s . -146-M i c r o s c o p i c : F e l d s p a r ( p l a g i o c l a s e ) G r a i n - s i z e Quartz Epidote groundmass 0.02 x 0.16 mm to 1.40 x 1.04 mm phenocrysts 0.92 x 1.38 to 4.14 x 2.76 mm very minor amounts 0.16 to 0.40 mm forming aggregates 2.7 x 1.4 mm C a l c i t e C h l o r i t e 0.8 mm Texture: Fragmental, s l i g h t l y p o r p h y r i t i c fragments of f e l t e d f e l d s p a r l a t h s and gr a i n s w i t h abundantly disseminated aggregates of medium to coarse-grained anhedral to subhedral epidote. A l s o angular f r a g -ments of porphyry w i t h t r a c h y t i c f e l d s p a t h i c groundmass w i t h w i d e l y disseminated coarser g r a i n s of epidote and p l a g i o c l a s e phenocrysts. 13. K63-91 Contact B r e c c i a , A s h c r o f t Macroscopic: Angular fragments of fine/medium grained f e l d s p a r and quartz-r i c h p l u t o n i c rock and tan-brown a p h a n i t i c porphyry w i t h w i d e l y disseminated phenocrysts i n an e p i d o t e - r i c h fragmental m a t r i x con-t a i n i n g abundant small rock fragments. M i c r o s c o p i c : P l a g i o c l a s e An 33 (extensive cloudy Orthoclase ? ( a l t e r a t i o n Quartz i n matri x 307.; i n p l u t o n i c fragments 107. Epidote aggregates of g r a i n s C h l o r i t e C a l c i t e A l t e r a t i o n products pseudomorphous a f t e r hornblende w i t h hematite i n cleavage traces g i v i n g the appearance of having forced the cleavage planes apart. Texture: Fragmental. P l u t o n i c rock fragments and broken c r y s t a l s . P o o r l y developed micrographic t e x t u r e , quartz a l b i t e on a l b i t i z e d margins of p l a g i o c l a s e c r y s t a l s . 14. K63-89a-III I n t r u s i v e B r e c c i a Macroscopic: Angular fragments of dark green-grey porphyry w i t h s p a r s e l y disseminated phenocrysts i n a f i n e - g r a i n e d i n t r u s i v e rock m a t r i x w i t h c r y s t a l s l e s s than 1/2 to approximately 1 mm. E p i d o t e - r i c h , most abundant at contacts w i t h b r e c c i a fragments. -147-M i c r o s c o p i c : B r e c c i a fragments; porphyry Groundmass; f e l d s p a t h i c l a t h s , m i c r o c r y s t a l l i n e , i n d i s t i n c t o u t l i n e s clouded by a l t e r a t i o n . Widely disseminated f e l d s p a r . Phenocrysts cut by minute epidote s t r i n g e r s and c l o t s . M a t r i x : Estimated % P l a g i o c l a s e An 3g 55% .95 x .70 to .55 x .46 mm clouded w i t h a l t e r a t i o n Orthoclase? Quartz 10% .90 x .25 to 0.10 x 0.10 mm Pyroxene 5% .56 x 70 mm Epidote 15% .32 x 0.06 to .20 x .20 mm (forms C h l o r i t e 5% 1.38 diameter to 0.83 x (aggregate .28 mm (of g r a i n s C a l c i t e 5% Magnetite 5% I l m e n i t e and leucoxene 15. K63-67 Metavolcanic, east side of b a t h o l i t h , n o r t h of Witches Brook Macroscopic: Dark grey, f i n e - g r a i n e d , mafic d i f f i c u l t to d i s t i n g u i s h from grey f e l d s p a r s . Scattered i r r e g u l a r coarse-grained patches w i t h i n d i s t i n c t o u t l i n e composed of f e l d s p a r , mafic and e p i d o t e . Scattered pods of f i n e - g r a i n e d epidote aggregates to 3/4 i n c h diam-e t e r . Epidote h e a l i n g i n c i p i e n t f r a c t u r e s . M i c r o s c o p i c : P l a g i o c l a s e Quartz Hornblende Epidote Sphene Garnet Opaque (An72) Bytownite s l i g h t s e r i c i t i c a l t e r a t i o n traces anhedral anhedral, aggregates of g r a i n s traces Magnetite trace c h a l c o p y r i t e T e x t u r e : (a) Pavement t e x t u r e , f i n e - g r a i n e d anhedral g r a i n s of p l a g i o c l a s e , hornblende and sphene, p o s s i b l y represents r e c r y s t a l l i z a t i o n w i t h i n a crushed zone. (b) P o i k i l o b l a s t i c t e x t u r e , f i n e - g r a i n e d anhedral g r a i n s of hornblende and sphene forming a sieve texture i n coarse-grained p l a g i o c l a s e . (c) Coarse lenses w i t h mineral assemblage as above, crushed appear-ance, more abundant anhedral g r a i n s of i n t e r s t i t i a l e p i d o t e . Horn-blende and p l a g i o c l a s e anhedral g r a i n s w i t h i n d i s t i n c t o u t l i n e . Note: Hornblende, as anhedral g r a i n s , forms a discontinuous b e a d - l i k e f r a c t u r e f i l l i n g . -148-16. K63-77 Metavolcanic, east margin of b a t h o l i t h north of Witches Brook Megascopic: Dark grey to b l a c k , f i n e - g r a i n e d . M a f i c s not conspicuous. Few s c a t t e r e d patches s l i g h t l y coarser grained. Massive, dense. M i c r o s c o p i c : G r a i n - s i z e P l a g i o c l a s e (An^g) 0.64 x 0.16 mm euhedral/subhedral l a t h s 0.32 x 0.08 mm speckled w i t h s e r i c i t i c a l t e r a t i o n a c i c u l a r aggregates of grains Texture: No marked preferred o r i e n t a t i o n of p l a g i o c l a s e , forms a f e l t e d groundmass. Amphibole and augite have ragged obscure o u t l i n e s . Note: Amphibole and biotite(secondary) f i l l s small v e i n l e t s c u t t i n g across the section. 17. K63-143d Metavolcanic, Mamit Lake Macroscopic: Medium dark grey, mottled w i t h - t a n , f i n e - g r a i n e d . M a f i c , 15%, f i n e - g r a i n e d , not r e a d i l y v i s i b l e . Brown s t a i n i n g i n f r a c t u r e s . M i c r o s c o p i c ; P l a g i o c l a s e (An4g) Quartz Augite Hornblende Hypersthene? B i o t i t e Opaque magnetite Texture: S e r i a t e , p l a g i o c l a s e shows marked p r e f e r r e d o r i e n t a t i o n . Hornblende has ragged i n t e r s t i t i a l sieve t e x t u r e , i r r e g u l a r connected and i s o l a t e d anhedral g r a i n remnants of augite and an-hedral opaques. Note: hornblende f i l l s f r a c t u r e s . T r e m o l i t e / a c t i n o l i t e Augite B i o t i t e C h l o r i t e C a l c i t e Opaques -149-Hybrid Phases 18. K63-24 Hybrid Quartz D i o r i t e Porphyry, Barnes Lake Macroscopic: P o r p h y r i t i c , coarse-grained a l t e r e d feldspar c r y s t a l s i n a fine-grained groundmass, mottled l i g h t and medium grey, flecked with greenish tan. Grains approximately 1 mm with abundant scattered grains greater than 3 mm. Mafic minerals not recogniz-able, a l t e r e d . Microscopic: Estimated % Grain-size Plagioclase a l t e r e d 60% phenocrysts 1.84 x 1.12 mm groundmass 0.92 x 0.23 mm Quartz 25% • 0.48 mm and 0.96 mm Orthoclase p e r t h i t i c 5% Hornblende c h l o r i t i c 5% 0.40 x 0.16 mm Zircon 0.10 x .05 mm : Sphene S e r i c i t e Prehnite? Epidote C h l o r i t e Carbonate Opaque (magnetite, ilmenite, leucoxene) 0.14 x 0.14 mm • 0.46 x 0.18 mm Texture: P o r p h y r i t i c , micrographic texture poorly developed, very weak preferred o r i e n t a t i o n . Quartz occurs as anhedral grains and micro-graphic intergrowths with p l a g i o c l a s e . Mafics are ragged anhedral, 19. K.63-25 Granophyric Porphyry, Barnes Lake Macroscopic: L i g h t grey-green, extensive a l t e r a t i o n (epidote) tan t i n t , flecked with pink, fine/very fine-grained scattered medium to coarse-grained phenocrysts. Mafic a l t e r e d , very f i n e to medium-grained i n d i s t i n c t spots which may represent a l t e r e d mafic minerals. Microscopic: Plagioclase Orthoclase Quartz (An38) . (An 27?) Grain-size 0.47 x 1.38 mm 1.84 x 1.00 mm 0.46 x 0.23 1.15 x 0.32 0.32 x 0.18 0.16 x 0.24 mm euhedral phenocrysts rimmed by a l b i t e anhedral groundmass p e r t h i t i c -150-C h l o r i t e Carbonate) Epidote ) a l t e r a t i o n of p l a g i o c l a s e S e r i c i t e ) ' Opaque magnetite Texture: P o r p h y r i t i c , granophyric showing micrographic i n t e r g r o w t h of quartz and c l e a r a l b i t e rimming a l t e r e d p l a g i o c l a s e . A l t e r e d > ( s e r i c i t i c , e p i d o t i z e d , carbonatized) p l a g i o c l a s e rimmed by c l e a r a l b i t e . 20. K.63-26 Hybrid Quartz D i o r i t e , Barnes Lake Macroscopic: L i g h t cream-green grey, fine/medium-grained w i t h s c a t t e r e d medium to coarse-grained, most g r a i n s approximately 2 mm, green a l t e r a t i o n . M afic 15 to 20%, predominantly hornblende l e s s than 1 mm to 2 mm, tendency to form aggregates of very f i n e g r a i n s . M i c r o s c o p i c : Estimated % G r a i n - s i z e P l a g i o c l a s e (An34) 45% ' 2.30 X 1.38 mm 1.84 X 0.69 Orthoclase 5% Quartz 25% 1.00 X 0.46 0.70 X 0.44 Hornblende •15% 0.46 X 1.38 0.23 X 0.23 B i o t i t e ? A p a t i t e 0.51 X 0.16 s e r i c i t i z e d , e p i d o t i z e d a l b i t i c r i m s , p e r t h i t i c c h l o r i t i z e d i x 0.16 Sphene Epidote S e r i c i t e C h l o r i t e P rehnite Opaque (magnetite, i l m e n i t e ) rimmed by sphene Texture: Feldspar shows p r e f e r r e d o r i e n t a t i o n . So completely a l t e r e d that i t i s d i f f i c u l t to determine p l a g i o c l a s e composition or to conf i r m the presence of o r t h o c l a s e . P l a g i o c l a s e rimmed; rims are a l b i t i c . Quartz i s i n t e r s t i t i a l , a l a t e replacement of f e l d s p a r . 21. K.63-56 Granophyric Hybrid Quartz D i o r i t e , Barnes Lake Macroscopic: M o t t l e d l i g h t grey and grey-green, a l t e r a t i o n of p l a g i o -c l a s e , f i n e - g r a i n e d , quartz present but not conspicuous. Spotted by aggregates of very f i n e g r a i n s ; c h l o r i t i c , massive. -151-M i c r o s c o p i c : Estimated °h P l a g i o c l a s e ( A n 3 6 ? ) 40% Quartz Augite Hornblende C h l o r i t e Epidote Sphene" S e r i c i t e Opaques 30% G r a i n - s i z e 1.93 x 0.92 mm 1.93 x 0.46 mm 0.99 x 0.48 mm 0.48 x 0.32 mm 0.32 x 0.24 mm 0.18 x 0.05 mm 0.11 x 0.02 mm 1.20 x 0.96 mm 0.24 x 0.96 mm 0.64 x 0.24 mm 0.32 x 0.24 mm 0.08 x 0.11 mm (magnetite, i l m e n i t e ) l e s s than 57„ 25% s t r a i n e d e x t i n c t i o n e n c r u s t a t i o n around opaques Texture: P o o r l y developed micrographic texture and replacement of f e l d s p a r by quartz l e a v i n g g h o s t - l i k e shreds of f e l d s p a r showing uniform e x t i n c t i o n . M a f i c s form aggregates of f i n e g r a i n s . 22. K.63-54 Hybrid Quartz D i o r i t e , Barnes Lake Macroscopic: Medium grey-green, extensive a l t e r a t i o n of p l a g i o c l a s e to epid o t e , medium to coarse-grained ( 2 - 3 mm) s l i g h t l y p o r p h y r i t i c t e x t u r e . Contains a p a r t i a l l y a s s i m i l a t e d i n c l u s i o n of f i n e -grained rock r i c h e r i n mafic. M a f i c : 10%, hornblende, very f i n e -grained/medium-grained, l e s s than 1 mm to l a r g e r than 1 mm, occurs ' as aggregates of g r a i n s . Massive. M i c r o s c o p i c : Estimated 7, G r a i n - s i z e P l a g i o c l a s e (An 36) 40% 1.61 X 2.98 mm e x t e n s i v e l y a l t e r e d 1.39 X 1.20 mm to s e r i c i t i c and epidote Quartz 30% 0.46 X 0.51 mm • 1.20 X 1.-30" mm mottled e x t i n c t i o n Hornblende 5% 1.16 X 0.42 mm 0.83 X 0'.37 mm ragged, c h l o r i t i z e d Prehnite? Epidote 0.07 X 0.03 mm aggregates of g r a i n s S e r i c i t e C h l o r i t e A p a t i t e Sphene - ragged g r a i n s e n c r u s t i n g and c u t t i n g Z i r c o n .0.23 x 0.08 mm Opaques leucoxene, i l m e n i t e , magnetite -152-Texture: P r e f e r r e d o r i e n t a t i o n of p l a g i o c l a s e and m a f i c s , p o o r l y d e v e l -oped micrographic t e x t u r e . Quartz anhedral, r e p l a c i n g p l a g i o c l a s e , mottled e x t i n c t i o n , f r a c t u r e d . Hornblende, ragged o u t l i n e , p a r t i a l replacement by quartz (and f e l d s p a r ) . 23. K.63-55 Granophyric Porphyry, Barnes Lake Macroscopic: Medium g r e y i s h pink, e x t e n s i v e l y a l t e r e d , f i n e - g r a i n e d , 1 mm or l e s s . Scattered medium to coarse-grained p o r p h y r i t i c g r a i n s l a r g e r than 2 mm. Abundant disseminated green to y e l l o w epidote. M a f i c ; trace very f i n e - g r a i n e d , black w i d e l y disseminated, aggregates of g r a i n s . C h l o r i t i c . M i c r o s c o p i c : Estimated % G r a i n - s i z e P l a g i o c l a s e (An^g) 45% 1.82 X 1.82 mm g r a p h i t i c 0.72 X 0.64 mm a l t e r e d 0.72 X 0.24 mm phenocrysts 0.25 X 0.21 mm Orthoclase i n t e r s t i t i a l Quartz 45% 0.16 X 0.16 mm 0.72 X 0.27 mm B i o t i t e Augite? Sphene Epidote . 0.04 x 0.02 mm C h l o r i t e S e r i c i t e Carbonate Pr e h n i t e Opaques 3%, ( p y r i t e , magnetite) Texture: M i c r o g r a p h i c , p o r p h y r i t i c . Widely s c a t t e r e d f e l d s p a r pheno-c r y s t s , most are euhedral w i t h a l b i t e overgrowths showing micro-graphic texture w i t h quartz. Ragged o u t l i n e of some p l a g i o c l a s e suggests replacement. A l t e r a t i o n of p l a g i o c l a s e appears to be s e l e c t i v e . 24. K.63-62 Hybrid G r a n o d i o r i t e , Penny Lake Macroscopic; L i g h t to medium green-grey, mottled by orange-tan s t a i n -i n g , f i n e to medium-grained, s c a t t e r e d medium to coarse-grained o r t h o c l a s e w i t h i n t e r s t i t i a l p o i k i l i t i c t e x t u r e . M a f i c : 20%, b i o t i t e ^ augite and hornblende, very f i n e - to medium-grained, f a i r l y evenly d i s t r i b u t e d aggregates of g r a i n s . Massive, no marked f o l i a -t i o n . -153-Microscopic: Estimated % Grain-size P l a g i o c l a s e (An^g) 40% 0.48 X 2.30 mm ) most g r a i n s i n t e n s e l y 0.50 X 1.84 mm ) a l t e r e d . Trace of 1.15 X 0.41 mm ) normal zoning. Orthoclase 10% 1.38 X 2.97 mm ) i n t e r s t i t i a l p o i k i l i -0.15 X 0.23 mm ) t i c masses Quartz 25% . B i o t i t e ' 5% 0.80 X 0.56 mm ragged, warped Augite • 10% • 0.06 X 0.04 mm 0.07 X 0.04 mm Hornblende < 5% sieve texture Epidote aggregates of gr a i n s i n t e r s t i t i a l c r y s t a l s C h l o r i t e Prehnite? A p a t i t e 0.05 X 0.13 mm Opaque 2% 0.26 X 0.10 mm 0.16 X 0.16 mm • 0.08 X 0.08 mm Texture: Hypidiomorphic g r a n u l a r , s l i g h t l y p o r p h y r i t i c , weak p r e f e r r e d o r i e n t a t i o n of p l a g i o c l a s e , subhedral/euhedral l a t h s , e xtensive a l t e r a t i o n , s e r i c i t e , e pidote, prehnite and carbonate. 25. K63-96 Hybrid Quartz D i o r i t e , Studhorse Creek Macroscopic: M o t t l e d l i g h t green-grey and cream, st a i n e d tan, medium-grained, most g r a i n s 1 - 2 mm, quartz not conspicuous. Mafic:' 15%,: b i o t i t e =. hornblende, l e s s than 1 to 2 ram, tends to form aggregates of g r a i n s . Massive. M i c r o s c o p i c : Estimated % G r a i n - s i z e P l a g i o c l a s e (An46 35% 1.40 X 0.73 mm A n31» An25> 1.28 X 0.31 mm Orthoclase <10% Quartz 35% 0.90 X 1.15 mm 1.00 X 0.55 mm Hornblende <10% 0.50 X 0.50 mm 2.06 X 0.65 mm Augite? B i o t i t e < 5% 0.55 X 1.38 mm 1.00 X 1.15 mm A p a t i t e • 0.10 X 0.06 mm Sphene Zircon? 0.17 X 0.08 mm C h l o r i t e -154-Carbonate Prehnite? Opaque (magnetite) <5% Texture: Hypidiomorphic g r a n u l a r , weak p r e f e r r e d o r i e n t a t i o n of p l a g i o -c l a s e . Orthoclase i n t e r s t i t i a l , s l i g h t " d u s t i n g " of a l t e r a t i o n . B i o t i t e somewhat shredded, ragged o u t l i n e , replacement by q u a r t z , warped g r a i n s , p o i k i l i t i c a l l y e n c l o s i n g a p a t i t e . Hornblende g r a i n s warped, few include small l a t h s of p l a g i o c l a s e . 26. K63-13 . Hybrid Quartz D i o r i t e , Highland V a l l e y road 13 m i l e s from A s h c r o f t Macroscopic: Light/medium grey-green, fine/medium-grained, green a l t e r a -t i o n of p l a g i o c l a s e , s l i g h t l y p o r p h y r i t i c , quartz not conspicuous. M a f i c 15%, b i o t i t e greater than hornblende, very f i n e to medium-grained, f a i r l y evenly disseminated. Massive. M i c r o s c o p i c : G r a i n - s i z e P l a g i o c l a s e 50% 0.55 X 1.15 mm 2.40 X 2.40 mm Orthoclase 10% ' Quartz 25% 1.36 X 2.06 mm Hornblende 5% 0.60 X 0.68 mm 1.83 X 0.68 mm B i o t i t e 5% 0.96 X 2.30 mm 1.60 X 3.68 mm Augite trace C h l o r i t e Epidote Sphene 0.68 X 0.37 mm Zi r c o n Opaque (magnetite) 2% 0.13 X 0.13 mm 0.50 X 0.18 mm Texture: Equigranular, marked p r e f e r r e d o r i e n t a t i o n of p l a g i o c l a s e . M a f i c s show some tendency to form aggregates of g r a i n s which are f a i r l y evenly disseminated. 27. K64-15 Hybrid Quartz D i o r i t e , Spatsum Macroscopic: Medium grey-green ( a l t e r a t i o n of p l a g i o c l a s e ) , medium-grained, quartz not conspicuous, s c a t t e r e d discontinuous s t r i n g e r s of o r t h o c l a s e . M a f i c 15%,, hornblende (and a u g i t e ) minor b i o t i t e , very f i n e to medium-grained, aggregates of g r a i n s evenly d i s t r i b u t e d , f o l i a t e d . -155-Microscopic: • Grain-size Plagioclase 50% 1.24 X 1.37 mm 2.40 X 0.73 mm Orthoclase <5% Quartz ' 25% 0.55 X 1.00 mm 0.91 X 0.82 mm Hornblende 10% • 0.91 X •1.15 mm 0.91 X 0.73 mm Augite ? B i o t i t e <5% C h l o r i t e Epidote r 0.36 X 0.60 mm Carbonate S e r i c i t e Opaque 1% 0.64 X 0.18 mm 0.13 X 0.18 mm Texture: Hypidiomorphic granular, f o l i a t i o n evident by mafics and to lesser extent by feldspar. Cut by v e i n l e t s of carbonate and s e r i c i t e . 28. K64-10 Hybrid Quartz D i o r i t e , Highland V a l l e y road 12 miles from Ashcroft Macroscopic: Mottled l i g h t to medium cream-grey and green grey, f i n e / medium-grained, quartz not conspicuous. Mafic very fin e to f i n e -grained, more than 10% medium green-grey augite? forms mafic r i c h c l o t s and aggregates of grains, random d i s t r i b u t i o n . Trace dissem-inated c h a l c o p y r i t e . Microscopic: Plagioclase (Ajrjg) . 60% 1.84 X 1.38 mm ) extensive epidote - 2.76 X 1.38 mm ) and s e r i c i t e a l t e r a t i o n Quar tz 20% Augite 2.62 X 0.91 mm 0.91 X 0.91 mm Hornblende 0.55 X 0.46 mm B i o t i t e Sphene Zircon Opaque (magnetite, ilmenite) 0.46 X 0.32 mm rimmed by sphene -156-29. K63-133b-III Hybrid Quartz D i o r i t e , Ridge between Inkikuh and Pemainus Creeks Macroscopic: Medium grey-green, mottled with tan, fine/medium-grained, scattered coarse-grained, s l i g h t l y p o r p h y r i t i c , quartz conspicuous, f o l i a t e d , discontinuous patches of feldspar same cleavage o r i e n t a -t i o n . Mafic: 20%, b i o t i t e more than hornblende fine/medium-grained f a i r l y evenly disseminated, b i o t i t e shows f o l i a t i o n . Microscopic: Grain-size Plagioclase (An44) 45%, 1.15 x 0.32 mm 2.11 x 0.92 mm Quartz . . ' ' 25% • 0.46 x 0.46 mm 1.24 x 1.22 mm B i o t i t e >10% .0.96 x 0.68 mm 1.56 x 0.82 mm Hornblende ^10% .1.56x0.82 mm 2.06 x 0.92 mm Augite <5% 0.46 x 0.92 mm C h l o r i t e S e r i c i t e Zircon Sphene 0.09 x 0.13 mm Apatite 0.05 x 0.07 mm Opaque (magnetite, hematite, chalcopyrite) 0.04 x 0.04 mm 0.16 x 0.22 mm Texture: Hypidiomorphic, granular. Preferred o r i e n t a t i o n of p l a g i o -clase, scattered grains ^how strong s e r i c i t i c a l t e r a t i o n . Quartz anhedral, i n t e r s t i t i a l . a f i c s anhedral, i r r e g u l a r , s l i g h t p o i k i l i -t i c texture, hornblende enclosing remnant augite, and opaques; b i o t i t e enclosing opaques, plagioclase and a p a t i t e . 30. K63-144-III Hybrid Quartz D i o r i t e , Piraainus H i l l s Macroscopic: L i g h t grey, mottled greenish, f i n e - to medium-grained. Quartz not conspicuous. M a t r i x : 25%, augite more abundant than b i o t i t e . M i c r o s c o p i c : P l a g i o c l a s e ( A n 4 5 ) 45% 2.30 x 0.73 mm 1.10 x 1.93 mm Orthoclase 10% 1.83.x 0.56 mm 2.95 x 0.92 mm Quartz 15% 0.60 x 0.58 mm 1.05 x 0.65 mm I -157-Augite 10% Hypersthene ^ 10% 0.68 X 0.68 mm - 1.38 X 0.27 mm B i o t i t e 5% 2 : 0 7 X 1.84 mm 0.92 X 0.32 mm Apatite trace Opaque (magnetite) 5% Texture: Traces of micrographic (herringbone) texture in v o l v i n g quartz and p l a g i o c l a s e . Plagioclase euhedral/subhedral with 2 preferred .orientations, warped c r y s t a l s , s e l e c t i v e s e r i c i t i c a l t e r a t i o n , s l i g h t l y p o r p h y r i t i c texture. Quartz i n t e r s t i t i a l . Augite has p o i k i l i t i c texture enclosing plagioclase and traces of hypersthene, 31. ' K.63-79-I Hybrid D i o r i t e , Southeast of Glossy Mountain Macroscopic: Matrix 50%, plagioclase, l i g h t to medium grey, flecked with tan, medium grained, no v i s i b l e quartz. Mafic: 50%,, gives rock dark appearance, augite with 57, brown b i o t i t e with p o i k i l i t i c texture, mafic forms aggregates of f i n e to medium grains. Massive. Microscopic: Grain-size Plagioclase (Anso) 40% Augite 407, B i o t i t e 5% Hornblende < 5% Hypersthene ? Carbonate trace S e r i c i t e C h l o r i t e Opaque (magnetite, ilmenite, leucoxene) Texture: Augite has a p o i k i l i t i c texture enclosing small anhedral grains of plagioclase and opaques. Smaller augite grains form a sieve texture i n hornblende. Plagioclase shows a very weak preferred o r i e n t a t i o n . 32. K63-93 Hybrid Quartz D i o r i t e , A n t l e r Lake Macroscopic: Mottled medium grey with green t i n t and tan, fine/medium-grained, equigranular, quartz not conspicuous i n hand specimen. Mafic 207,, fine/medium-grained, hornblende more abundant than b i o t -i t e , forms aggregates of grains which are evenly disseminated. Massive. -158-'Microscopic: Plagioclase (An^g) 50% Quartz 15% B i o t i t e 10% Hornblende 10% Augite 2% C h l o r i t e S e r i c i t e Opaque (magnetite) Texture: Hypidiomorphic granular. Plagioclase shows marked preferred o r i e n t a t i o n , subhedral/anhedral, few grains showing s e r i c i t i c a l t e r a t i o n . Hornblende and b i o t i t e are anhedral, i n t e r s t i t i a l and p o i k i l i t i c a l l y enclose pl a g i o c l a s e , quartz and opaque grains. Quartz i s anhedral, i n t e r s t i t i a l to p l a g i o c l a s e . 33. K64-156a Hybrid Quartz D i o r i t e / G r a n o d i o r i t e , Craigmont Macroscopic: Mottled medium tan-grey and medium to dark grey, f i n e - to medium-grained, equigranular, quartz not conspicuous. Mafic l e s s than 10%, b i o t i t e more abundant than hornblende, forms aggregates of grains with random d i s t r i b u t i o n . Microscopic: Graia-size Plagioclase (An38) centre) 0.64 x 1.84 mm (An27) edges j 40% 1.01 x 0.68 mm Orthoclase 10% 0.92 x 0.46 mm 0.41 x 0.22 mm Quartz 25% 0.27 x 0.48 mm 0.68 x 0.46 mm Augite 10% 1.15 x 0.56 mm B i o t i t e 10% ,1.84 x 1.28 mm 0.73 x 0.46 mm . Hypersthene? S e r i c i t e Zircon Apatite Opaque (magnetite) Texture: Hypidiomorphic granular, showing a marked preferred o r i e n t a -t i o n of p l a g i o c l a s e . Orthoclase shows traces of myrmekitic texture with quartz. -159-34. K63-78 Hybrid Quartz D i o r i t e , East side of b a t h o l i t h north of Witches Brook Macroscopic: L i g h t grey with green t i n t , mottled with cream, fineW/ medium-grained, quartz not conspicuous. Massive. Mafic 15%, black, fine-grained, aggregates of hornblende c r y s t a l s . Specimen appears f a i r l y free of a l t e r a t i o n . Microscopic: Grain-size Plagioclase (An 38) 55% . 0.54 x 2.76 mm 2.99 x 0.82 mm 1.74 x 2.53 mm .0.41 x 0.32 mm Quartz < 5% 0.27 x 0.46 mm 0.46 x 1.69 mm Hornblende 15% 1.14 x 1.14 mm 0.54 x 0.83 mm 3.13 x 1.98 mm Augite trace B i o t i t e trace C h l o r i t e A c t i n o l i t e Zircon Opaque (magnetite) 0.71 x 0.28 mm 0.03 x 0.03 mm Texture: Plagioclase shows a preferred o r i e n t a t i o n , subhedral, f r e s h . Hornblende, i n t e r s t i t i a l , anhedral, p o i k i l i t i c texture, enclosing rounded anhedral augite, p l a g i o c l a s e , opaques. Quartz anhedral i n t e r s t i t i a l . 35. K63-77a-I Hybrid Quartz D i o r i t e , East side of b a t h o l i t h north of Witches Brook Macroscopic: Light/medium grey, fine-/medium-grained, low quartz content, not conspicuous. Mafic 10-15% hornblende more, abundant than b i o t i t e . Massive. Microscopic: Plagioclase (An^g) 65% (4.15 x 0.77 mm (2.76 x 0.22 mm (1,56 x 0.64 ram Quartz- <10% (0.68 ,x 0.54 mm (0.41 x 0.22 mm Hornblende 15% 1.38 x 0.69 mm 1.28 x 0.41 mm -160-Augite 2% A c t i n o l i t e trace B i o t i t e Muscovite? trace Epidote trace 0.08 x 0.08 mm Carbonate trace C h l o r i t e trace Opaque (magnetite) 0.17 x 0.22 mm 0.46 x 0.32 mm Texture: Hypidiomorphic granular, f r e s h . Plagioclase, subhedral, marked preferred o r i e n t a t i o n , no zoning, flecked with s e r i c i t i c and epidote a l t e r a t i o n . Quartz i s i n t e r s t i t i a l . Hornblende, few grains have a sieve texture, aggregates of grains p o i k i l i t i c a l l y enclosing minute opaques and p l a g i o c l a s e . Most grains p o i k i l i t i c , enclose augite and rounded grains of p l a g i o c l a s e . Mafic o c c a s i o n a l l y appears shredded and fibrous, (tremolite?) a l t e r a t i o n to c h l o r i t e . 36. K63-223 Guichon Granodiorite, Witches Brook Macroscopic: Mottled pink, white, l i g h t grey, medium-/coarse-grained. Most grains 2-3 mm. Quartz not conspicuous but v i s i b l e . Mafic less than 1 to more than 3 mm., approximately 15%,, with hornblende ^ b i o t i t e ; shows a tendency to form aggregates of grains which are evenly d i s s -eminated throughout the matrix. Massive. Microscopic: Grain-size Plagioclase (An_37) 45% (1.85 X 0.92 mm ( J l.37 X 1.84 mm (2.07 X 0.73 mm Orthoclase 10% (4.20 X 4.20 mm (3.22 X 2.76 mm (2.07 X 0.46 mm Quartz 20% (1.83 X 1.37 mm (0.92 X 1.56 mm Hornblende ' > 5% (1.38 X 0.78 mm (1.84 X 1.38 mm B i o t i t e 10% (3.45 X 2.76 mm (2.06 X 2.06 mm Augite < 5%. 0.02 X 0.04 mm C h l o r i t e < 5%' Apatite trace (0.21 X 0.07 mm (0.15 X 0.08 mm Sphene trace 0.82 X 0.32 mm Opaque (magnetite) <5% 0.13 X 0.13 mm 0.22 X 0.31 mm -161-Texture: P o i k i l i t i c . Orthoclase occurs as large i n t e r s t i t i a l masses, p o i k i l i t i c a l l y enclosing quartz, plagioclase and mafics, otherwise hypidiomorphic. Plagioclase i s subhedral showing a preferred o r i e n t a t i o n . Both hornblende and b i o t i t e have ragged o u t l i n e suggesting p a r t i a l replacement by feldspar and quartz. Quartz i s anhedral i n t e r s t i t i a l and shows mottled e x t i n c t i o n as a r e s u l t of s t r a i n . 37. K63-223-II Guichon Granodiorite, Witches Brook Macroscopic: Mottled, l i g h t cream-grey and pink, medium- to coarse-grained, most grains 1-3 mm. Quartz present but not conspicuous. Mafic 15%, hornblende = b i o t i t e , size less than 1 to more than 3 mm., p o i k i l i t i c texture, tendency to form aggregates of grains which are evenly disseminated. Massive. Microscopic: Plagioclase (AJ145) 45% Orthoclase 15% . Quartz 20% Hornblende <ao% B i o t i t e <10% Augite 1% Sphene < 1% Apatite trace S e r i c i t e Epidote trace Opaque (magnetite, chalcopyrite, hematite) ~>1% Texture: Hypidiomorphic granular, p o i k i l i t i c orthoclase and mafics. Plagioclase subhedral, shows preferred o r i e n t a t i o n . Orthoclase, anhedral, i n t e r s t i t i a l very coarse-grained, p e r t h i t i c . Quartz i n t e r s t i t i a l , anhedral with mottled e x t i n c t i o n r e s u l t i n g from s t r a i n . Hornblende anhedral, s l i g h t l y p o i k i l i t i c / s i e v e texture, enclosing augite granules, opaque (magnetite) and p l a g i o c l a s e . B i o t i t e anhedral, i n t e r s t i t i a l , p o i k i l i t i c , encloses a p a t i t e , warped grains. 38. K.63-7 Guichon Quartz D i o r i t e / G r a n o d i o r i t e , Two miles east of Bethlehem Copper Corporation Limited Macroscopic: Light cream-grey, mottled pink, fine-/medium-grained (1 to 2 mm). Feldspar predominantly p l a g i o c l a s e . Quartz present but not conspicuous. Mafic 15-20%, hornblende more abundant than b i o t i t e , very fine-/medium-grained, hornblende p a r t l y c h l o r i t i z e d , tendency to form evenly d i s t r i b u t e d aggregates of grains. Massive. -162-Microscopic: Grain-size Plagioclase (An33) 40% 2.65 x 1.38 Orthoclase 5% (2.30 mm (1.15 mm Quartz 25% 1.15 mm Augite 1% Hornblende 5% 2.30 x 1.28 B i o t i t e 15% ' 0.63 mm C h l o r i t e < 5% Apatite . trace 0.09 x 0.21 Zircon trace 0.08 mm Sphene trace 0.12 mm Opaques (magnetite) 1% Epidote trace C a l c i t e trace Prehnite trace Texture: Hypidiomorphic granular, weak p e r s i s t e n t preferred o r i e n t a -t i o n of p l a g i o c l a s e . Orthoclase occurs as i n t e r s t i t i a l p o i k i l i t i c masses enclosing plagioclase and quartz; minor cloudiness as a r e s u l t of a r g i l l i c ? a l t e r a t i o n . Quartz i s i n t e r s t i t i a l anhedral. B i o t i t e i s commonly warped and broken. / 39. K63-163 Guichon Quartz Monzonite, North side of Witches Brook Macroscopic: Li g h t cream-grey with s l i g h t green t i n t , mottled or flecked with pink, fine-/medium-grained, most grains 2-3 mm. Quartz present but not conspicuous. Mafic 15 to 20%, f i n e to medium-grained, most grains 1 to 2 mm, f a i r l y evenly disseminated aggregates of f i n e grains. Massive. Microscopic: Plagioclase (An45)' 20% 2.75 X 2.75 mm 0.70 X 1.85 mm Orthoclase 30% 2.75 X 2.55 mm 2.30 X 2.30 mm Quartz 20% ' 1.15 X 1.45 mm 0.95 X 0.95 mm Augite trace 0.46 X 0.60 mm Hornblende 5% 0.90 X 1.95 mm B i o t i t e 10% 2.10 X 0.65 mm 1.45 X 1.45 mm 0.65 X 0.83 mm Sphene trace Zircon trace 0.22 X 0.10 mm Opaque ' <5% 0.60 X 0.35 mm 0.10 X 0.15 mm C h l o r i t e trace S e r i c i t e -163-Texture: Hypidiomorphic granular. Plagioclase i s subhedral to euhedral, shows preferred o r i e n t a t i o n and s e l e c t i v e zones of s e r i c i t i c a l t e r a -t i o n . Orthoclase i s i n t e r s t i t i a l , p o i k i l i t i c , enclosing plagioclase and quartz. B i o t i t e p o i k i l i t i c a l l y encloses augite and shows weak c h l o r i t i c a l t e r a t i o n . 40. K63-136a-I Contaminated Guichon, North side Inkikuh Creek Macroscopic: Medium creamy green-grey mottled by pink strongly a l t e r e d , medium-grained, quartz present but not conspicuous. Mafic 20-257„, b i o t i t e a u g i t e (and hornblende), fine-/medium-grained and coarse-grained, aggregates of grains, f o l i a t e d . Microscopic: Grain-size Plagioclase 50% . 3.70 X 2.00 mm 2.50 X 1.00 mm Orthoclase < 5% 1.61 X 1.84 mm 3.22 X 1.14 mm Quartz 15% 2.30 X 1.14 mm 0.68 X 0.73 mm Hornblende 2% • 1.14 X 0.36 mm B i o t i t e 15% Augite 10% 0.92 X 0.83 mm 1.23 X 0.69 mm Zircon trace 0.17 X 0.10 mm 0.12 X 0.08 mm Apatite trace 0.07 X 0.02 mm Opaque 1% 0.68 X 0.59 mm 0.22 X 0.22 mm 0.17 X 0.55 mm C h l o r i t e Epidote < 5% (0.17 X 0.13 mm S e r i c i t e •(0.64 X 0.13 mm Texture: Hypidiomorphic .granular. Extensive a l t e r a t i o n of p l a g i o c l a s e , shows preferred o r i e n t a t i o n . Mafics have ragged o u t l i n e , p a r t i a l l y replaced. B i o t i t e shows extensive c h l o r i t i c a l t e r a t i o n , p o i k i l i t i c texture enclosing quartz, apatite,, opaques and p l a g i o c l a s e . Augite i s rimmed has been converted along c r y s t a l l a g r a p h i c planes to horn-blende (showing a l l stages of conversion from i n i t i a l to almost complete). Orthoclase i s i n t e r s t i t i a l , p o i k i l i t i c . Quartz i s p o i k i l i t i c , fractured and shows strained e x t i n c t i o n . Opaques tend to form aggregates of grains with mafics. -164-41. K63-196 Contaminated Guichon Quartz D i o r i t e , Woods Creek Macroscopic: Mottled cream and l i g h t grey, pinkish f l e c k s , medium-/ coarse-grained, quartz not conspicuous. Mafic 20 to 25%, b i o t i t e s=augite (and hornblende) fin e to medium-grained, weak f o l i a t i o n . Microscopic: Plagioclase (An 38) 60% Orthoclase N.D. Quartz >10% Augite > 5% • Hornblende < 5% B i o t i t e 15% Sphene trace Apatite trace Opaque < 57. (magnetite, ilmenite ?) S e r i c i t e Epidote C h l o r i t e Texture: Hypidiomorphic, granular. Plagioclase extensively a l t e r e d , marked preferred o r i e n t a t i o n . Mafics extremely ragged by p a r t i a l replacement and a l t e r a t i o n . B i o t i t e ragged, p o i k i l i t i c , enclosing quartz, p l a g i o c l a s e , mafics and sphene, p a r t i a l replacement by quartz, c h l o r i t i c a l t e r a t i o n . Augite ragged, rimmed by hornblende, showing a l l stages of conversion to hornblende from sieve texture enclosing hornblende to scattered anhedral grains i n hornblende. Quartz anhedral, i n t e r s t i t i a l , strained e x t i n c t i o n . Sphene rimming opaques suggests ilmenite or t i t a n i f e r o u s magnetite. 42. K64-50a V Guichon, Trojan Macroscopic: Mottled cream-tan and pink, f i n e - to medium-grained. Quartz not conspicuous. Mafic 15%,, very f i n e - to medium-grained, hornblende more abundant than b i o t i t e , forms evenly disseminated aggregates of grains. Massive. Microscopic: Plagioclase ( A n 4 o ) 50% Orthoclase 10% Quartz 20% : Augite < 1% Hornblende 10% B i o t i t e 5% Zircon trace Monzonite ? trace -165-Apatite trace Opaque 2% Prehnite ? Epidote C h l o r i t e Texture: Hypidiomorphic granular, extensive a l t e r a t i o n . Plagioclase subhedral/euhedral, shows preferred o r i e n t a t i o n , s e r i c i t i z e d and weakly epidotized. Orthoclase, i n t e r s t i t i a l , anhedral, p o i k i l i t i c enclosing p l a g i o c l a s e , apatite, monazite? and mafics, dusted by a reddish brown a r g i l l i c ? a l t e r a t i o n . Hornblende i n t e r s t i t i a l , anhedral, p o i k i l i t i c to sieve texture enclosing rounded grains and i r r e g u l a r ragged masses of augite, encloses plagioclase and opaques. B i o t i t e , anhedral shredded, c h l o r i t i z e d , contains lenses of quartz, prehnite., c h l o r i t e and epidote, p o i k i l i t i c , encloses pl a g i o c l a s e , opaques and their a l t e r a t i o n products. 43. K63-33b-I Guichon, Forge Mountain Macroscopic: Mottled cream, l i g h t grey and pink, medium- to coarse-grained. Quartz not conspicuous. Mafic 15 to 207», f i n e - to coarse-grained, hornblende more than b i o t i t e , s l i g h t tendency to form aggregates of grains which are evenly disseminated. Massive. Microscopic: Plagioclase (An^) 50% Orthoclase 10% Quartz 15% Hornblende 10% B i o t i t e 10% Zircon trace • Apatite trace Sphene trace Opaque (magnetite) 2% Prehnite? C h l o r i t e Epidote S e r i c i t e Texture: Hypidiomorphic, granular. Plagioclase euhedral/subhedral, weak preferred o r i e n t a t i o n , s e r i c i t i z e d , weakly epidotized. Ortho-clase, i n t e r s t i t i a l anhedral, p o i k i l i t i c , enclosing p l a g i o c l a s e , • opaques and mafics; dusted with reddish brown a r g i l l i c ? a l t e r a t i o n . Hornblende anhedral, p o i k i l i t i c / s i e v e texture, enclosing ragged c r y s t a l remnants and granules of augite, p o i k i l i t i c , enclosing epidote, opaques and feldspar. B i o t i t e ragged to shredded, c h l o r i -t i c a l t e r a t i o n . Quartz anhedral, i n t e r s t i t i a l , strained e x t i n c t i o n . -166-44. K63-185 Chataway Quartz Monzonite, East of Gnawed Mountain Macroscopic: Mottled pink and cream, medium- to coarse-grained, 2-3 mm with p o i k i l i t i c i n t e r s t i t i a l masses of orthoclase greater than 1 cm, quartz f a i r l y conspicuous. Mafic 10%, hornblende greater amounts than b i o t i t e , f i n e - to coarse-grained, 1 to 3 mm, hornblende has marked p o i k i l i t i c texture, sharp outline and i s evenly disseminated. Massive. Microscopic: Grain-size Plagioclase (An4fj) centre 50% (3.86 x 1.37 mm (An24) rim (2.53 x 0.68 mm Orthoclase 20% ' (6.90 x 4.60 mm (3.86 x 4.60 mm Quartz 15% (1.61 x 1.37 mm (4.11 x 1.84 mm B i o t i t e < 5% 1.14 x 1.61 mm Hornblende >5% (3.32 x 1.84mm (0.68 x 0.73 mm Apatite trace 0.10 x 0.17 mm Sphene trace (0.03 x 0.04 mm (0.02 x 0.03 mm Opaques (magnetite) < 3% Ch l o r i t e 0.15 x 0.38 mm S e r i c i t e Texture: Hypidiomorphic granular, p o i k i l i t i c . Plagioclase subhedral to euhedral, s e r i c i t i c a l t e r a t i o n weak preferred o r i e n t a t i o n . Orthoclase i n t e r s t i t i a l p o i k i l i t i c , p e r t h i t i c , p a r t i a l l y replaces some e a r l i e r minerals. Hornblende has a marked p o i k i l i t i c texture, corroded margins, replaced by orthoclase and quartz. B i o t i t e shows i r r e g u l a r margins as a r e s u l t of replacement by orthoclase and quartz. Sphene i s i n i r r e g u l a r grains, intimate a s s o c i a t i o n with hornblende. Quartz, i n t e r s t i t i a l , anhedral, p o i k i l i t i c . Opaques associated with mafics. 45. K63-205-IV Chataway Quartz Monzonite, Chataway Lake Macroscopic: Mottled l i g h t cream-green, pink and l i g h t grey,-medium-to coarse-grained, most grains 2-3 mm but with scattered i n t e r s t i t -i a l p o i k i l i t i c masses of orthoclase approaching 1 cm. diameter. Quartz f a i r l y conspicuous. Mafic 10%,, more hornblende than b i o t i t e , f i n e - to coarse-grained, less than 1 to more than 4 mm, hornblende has p o i k i l i t i c texture, mafic outlines d i s t i n c t , evenly disseminated. Massive. -167-M i c r o s c o p i c : P l a g i o c l a s e (An^i) centre 55% ( A n 2 2 ) edge Orthoclase Grain-;i,18 x 1, Quartz Hornblende B i o t i t e Pyroxene A p a t i t e Sphene Zi r c o n 10% 20% < 5% > 5% trace trace trace trace Opaque (magnetite, p y r i t e ) 2 % C h l o r i t e S e r i c i t e '0.07 x 0.07 mm |0-.10 x 0.04 mm 0.15 x 0.08 mm 0.23 x 0.12 mm 0.92 x 0.55 mm Texture: Hypidiomorphic, g r a n u l a r , P l a g i o c l a s e subhedral, ragged edges by p a r t i a l replacement, p r e f e r r e d o r i e n t a t i o n . Orthoclase i n t e r -s t i t i a l , p o i k i l i t i c , e n c l o s i n g p l a g i o c l a s e l a t h s , quartz, b i o t i t e and hornblende. Quartz, i n t e r s t i t i a l , p o i k i l i t i c . Hornblende, marked p o i k i l i t i c , t e x t u r e i n c l u d i n g q u a rtz, f e l d s p a r , b i o t i t e and opaques. B i o t i t e , ragged o u t l i n e , warped g r a i n s , p o i k i l i t i c a l l y e n c l o s i n g euhedral a p a t i t e . Sphene i n t e r s t i t i a l to p l a g i o c l a s e , i n t i m a t e l y a s s o c i a t e d w i t h hornblende. 46. K63-34a-I Chataway G r a n o d i o r i t e , South of Cinder H i l l Macroscopic: M o t t l e d cream, l i g h t grey and pink, medium- to coarse-grained, most gr a i n s approximately 2 mm, s c a t t e r e d i n t e r s t i t i a l p o i k i l i t i c masses of orthoclase approaching 1 cm i n diameter. -Quartz f a i r l y conspicuous. Mafic 10%, f i n e - to coarse-grained, b i o t i t e approximately same amount as hornblende, hornblende has p o i k i l i t i c t e x t u r e , mafics sharp o u t l i n e , evenly disseminated. Massive. -168-Microscopic: Grain-size Plagioclase (An4^) 50% 4.11 x 1.84 mm 1.98 x 1.05 mm Orthoclase 5% 2.99 mm 2.76 mm Quartz 35% 1.84 mm 5.34 mm Hornblende < 5% 3.45 x 3.68 mm 4.11 x 4.11 mm B i o t i t e 5% < 1.61 x 2.53 mm 1.93 x 1.61 mm Apatite ' trace 0.06 x 0.05 mm 0.12 x 0.08 mm Sphene trace 0.22 x 0.26 mm 1.61 x 0.46 mm Zircon trace 0.62 x 0.36 mm 0.39 x 0.20 mm Opaque (magnetite) < 5% C h l o r i t e trace S e r i c i t e Texture: P o r p h y r i t i c , phenocrysts of p l a g i o c l a s e , hornblende and quartz i n f i n e r matrix. Plagioclase i s subhedral to anhedral showing preferred o r i e n t a t i o n . Orthoclase and quartz, i n t e r s t i t -i a l , p o i k i l i t i c , including plagioclase and mafics. Quartz has mottled e x t i n c t i o n . Hornblende has a marked p o i k i l i t i c texture. B i o t i t e , s l i g h t l y p o i k i l i t i c , ragged, replaced by c h l o r i t e at edges, scattered euhedral grains. Sphene i s i n t e r s t i t i a l to plagio-clase . 47. K.63-44 Chataway Granodiorite, Ridge west of C a l l i n g Lake Macroscopic: Mottled cream-green and pink, a l t e r a t i o n of p l a g i o c l a s e , coarse-grained, most grains 2 to 4 mm, quartz i n t e r s t i t i a l f a i r l y conspicuous. Mafic 10-15%, hornblende more abundant than b i o t i t e , c h l o r i t e (and epidote); hornblende has p o i k i l i t i c texture, some-what ragged o u t l i n e s , f a i r l y evenly disseminated. Microscopic: Plagioclase (An 3 3?) 60% 1.14 x 0.36 mm 4,11 x 1.14 mm Orthoclase 5% 2.53 x 1.61 mm Quartz 15% 3.22 x 1.37 mm 1.37 x 1.37 mm Hornblende 10% 2.99 x 1.47 mm 0.92 x 0.64 mm -169-B i o t i t e . 5% Apatite < 1% 0.15 x 0.25 ram 0.07 x 0.10 mm Sphene 1% . 1.61 x 0.68 mm 0.87 x 0.26 mm Zircon trace 0.17 x 0.11 mm Opaque (magnetite) 2% 0.13 x 0.17 mm 0.36 x 0.59 mm Prehnite? 0.17 x 0.08 mm Epidote C h l o r i t e C a l c i t e Texture: H o l o c r y s t a l l i n e , p o i k i l i t i c / p o r p h y r i t i c . Plagioclase shows marked preferred o r i e n t a t i o n . Orthoclase i s i n t e r s t i t i a l p o i k i -l i t i c , enclosing mafics and p l a g i o c l a s e . Quartz i s i n t e r s t i t i a l without marked p o i k i l i t i c texture. Hornblende, p o i k i l i t i c texture but f a i r l y small grains, corroded margins, i n t e r s t i t i a l to plagio-clase, a l t e r e d to c h l o r i t e , epidote, c a l c i t e , shredded appearance. 48. K64-116a Chataway Granodiorite, Farr Lake Macroscopic: Mottled cream and l i g h t grey, mottled with pink, coarse-grained. Quartz i n t e r s t i t i a l wedge-shaped. Mafic 10%, hornblende ( p o i k i l i t i c ) more abundant than b i o t i t e , f i n e - to coarse-grained, d i s t i n c t o u t l i n e , evenly disseminated. Massive. Microscopic: Grain-size Plagioclase (An38) centre 1.52 x 0.55 mm (An27) edge 55% 4.66 x 2.30 mm Orthoclase 5% 3.22 x 1.52 mm • 4.66 x 2.76 mm Quartz .25% 2.90 x 1.69 mm 1.28 x 1.37 mm Hornblende > 5% 1.28 x 0.46 mm 3.22 x 1.61 mm B i o t i t e > 5% 4.66 x 2.30 mm 4.66 x 3.45 mm Apatite trace 0.31 x 0.31 mm 0.36 x 0.31 mm Sphene trace 0.50 x 0.68 mm Zircon trace 0.31 x 0.12 mm Opaque (magnetite) > 1%, Ch l o r i t e S e r i c i t e Epidote -170-Texture: H o l o c r y s t a l l i n e , p o i k i l i t i c . Plagioclase shows normal zoning, preferred o r i e n t a t i o n . Trace of micrographic texture, quartz and a l b i t e at edges of plagioclase grains. Orthoclase, large i n t e r s t i t -i a l masses, p o i k i l i t i c enclosing p l a g i o c l a s e . 49. K63-220 LeRoy / Chataway, Dot Lake Macroscopic: Mottled cream and l i g h t grey, medium to coarse-grained. Orthoclase forms very coarse-grained p o i k i l i t i c i n t e r s t i t i a l masses. Quartz i n t e r s t i t i a l wedge-shaped. Mafic 10%, fine-/medium- and coarse-grained, subhedral p o i k i l i t i c hornblende more abundant than b i o t i t e , f a i r l y evenly disseminated, d i s t i n c t o u t l i n e . Massive. Microscopic: Grain-size Plagioclase (An37) 60% (1.84 X 0.73 mm (1.74 X 3.22 mm Orthoclase 10% >4.75 X 4.75 mm Quartz 15% (1.84 X 1.69 mm C2.53 X 2.30 mm Hornblende >10% (3.45 X 1.37 mm (2.76 X 2.07 mm B i o t i t e 2% . 3.22 X 1.61 mm Sphene trace ' 1.37 X 1.09 mm Zircon trace Opaque > 1% C h l o r i t e . Epidote Texture: P o r p h y r i t i c to s e r i a t e , p o i k i l i t i c . P l a g i o c l a s e , subhedral, o s c i l l a t o r y zoning, weak preferred o r i e n t a t i o n . Orthoclase occurs as large i n t e r s t i t i a l masses, p o i k i l i t i c a l l y enclosing plagioclase s l i g h t p e r t h i t i c texture. Quartz, i n t e r s t i t i a l , p o i k i l i t i c encloses p l a g i o c l a s e , mottled e x t i n c t i o n . Hornblende, p o i k i l i t i c texture enclosing plagioclase and opaques. B i o t i t e has a p o i k i l i t i c texture, s l i g h t c h l o r i t i c a l t e r a t i o n . Sphene i s i n t e r s t i t i a l anhedral. 50. K63-34 LeRoy, South side of Highland Valley opposite Cinder H i l l Macroscopic: Very l i g h t grey, mottled pink, medium-grained with scattered, coarse-grained p o i k i l i t i c phenocrysts of orthoclase. Abundant f a i r l y conspicuous, i n t e r s t i t i a l quartz. Mafic l 0 % , hornblende more abundant than b i o t i t e , very fine-/medium-grained tends to form aggregates of grains. Weak f o l i a t i o n . -171.-Microscopic: Plagioclase (An37) 35% Orthoclase Quartz Hornblende B i o t i t e Sphene Apatite Zircon Opaque (magnetite) C h l o r i t e Epidote 25% 30% 5%-3% 1% trace trace 2% trace trace Grain (0.31 x 0 (3.22 x 1 (1.88 x 0 3.68 mm (2.76 mm (0.46 x 0 (1.69 x 3 (0.92 x 0 (0.46 x 0 (2.76 x 0 (1.61 x (0.31 x 0 0.07 x 0 (0.31 x 0 (0.46 x 0 -size .22 mm .37 mm .59 mm .46 mm .55 mm .22 mm .31 mm . 68 mm 1.37 mm .31 mm .07 mm .07 mm , 68 mm 0.15 mm Texture: P o r p h y r i t i c , p o i k i l i t i c . Marked preferred o r i e n t a t i o n of euhedral/subhedral plagioclase and mafics. S e r i c i t i c a l t e r a t i o n of p l a g i o c l a s e . Quartz, anhedral i r r e g u l a r and subrounded, i n t e r -s t i t i a l to p l a g i o c l a s e . Sphene one very large, abundant small grains i n t e r s t i t i a l to and enclosing quartz and p l a g i o c l a s e . B i o t i t e i s i r r e g u l a r , i n t e r s t i t i a l , some grains shredded, with traces of c h l o r i t i c a l t e r a t i o n . Hornblende has p o i k i l i t i c texture, encloses p l a g i o c l a s e . Orthoclase, i n t e r s t i t i a l masses, e r r a t i c d i s t r i b u t i o n , p o i k i l i t i c a l l y enclosing a l l other primary minerals. Epidote minute i r r e g u l a r masses within hornblende. 51. K63-37 LeRoy, Southwest Flank of Forge Mountain Macroscopic: Mottled l i g h t cream-grey and pink, fine to medium-grained with scattered coarse i n t e r s t i t i a l p o i k i l i t i c orthoclase. Quartz i n t e r s t i t i a l , f a i r l y conspicuous. Mafic less than 10%, b i o t i t e hornblende, f i n e to medium-grained, well defined evenly d i s t r i b u t e d grains. Massive. Microscopic: Plagioclase 40% Orthoclase 20% Quartz 30% B i o t i t e < 5% Hornblende < 5% Zircon trace -172-Apatite trace Sphene trace Opaques 1% S e r i c i t e Texture: Hypidiomorphic, granular. Plagioclase subhedral, shows pre-ferred o r i e n t a t i o n , normal zoning. Orthoclase, anhedral i n t e r s t i t -i a l masses, p o i k i l i t i c , s l i g h t reddish brown a l t e r a t i o n . Quartz anhedral, i n t e r s t i t i a l , s l i g h t l y p o i k i l i t i c , mottled e x t i n c t i o n . B i o t i t e and hornblende ragged o u t l i n e , s l i g h t l y p o i k i l i t i c texture, b i o t i t e has warped, grains. 52. K64-101 LeRoy Quartz Monzonite, Broom Creek Macroscopic: Mottled medium grey, yellowish tan, minor creamy pink, f i n e - to medium-grained, scattered coarse-grained, quartz i n t e r -s t i t i a l , scattered sphene. Mafic 10%, b i o t i t e more abundant than hornblende, tendency to form aggregates of grains, ragged o u t l i n e s . Microscopic: Grain-size Plagioclase (An33) 45%' (2.07 x 1.61 mm (0.50 x 1.93 mm Orthoclase 15% (1.52 x 1.28 mm (1.14 x 0.83 mm Quartz 25% 0.92 x 0.87 mm B i o t i t e 5% 1.28 x 0.87 mm Hornblende 5% 0.68 x 0.46 mm Sphene trace 0.46 x 0.46 mm Apatite trace 0.23 x 0.12 mm Opaque (magnetite) < 2% Epidote Texture: H o l o c r y s t a l l i n e . Plagioclase shows s e r i c i t i c a l t e r a t i o n and weak preferred o r i e n t a t i o n . Orthoclase i s anhedral, i n t e r s t i t i a l , p o i k i l i t i c , enclosing quartz and p l a g i o c l a s e . Quartz i s rounded, granular, i n t e r s t i t i a l , p o i k i l i t i c , enclosing plagioclase and shows strained e x t i n c t i o n . The mafics, b i o t i t e and hornblende, have p o i k i l i t i c textures and ragged o u t l i n e s . Sphene i s anhedral i n t e r -s t i t i a l . Opaques are intimately associated with mafics. 53. K.64-54 LeRoy Quartz Monzonite, Ridge south side of Witches Brook Macroscopic: Mottled cream and very l i g h t grey, s l i g h t p i n k i s h t i n t , medium-grained. Quartz not conspicuous. Mafic 10%, hornblende more abundant than b i o t i t e , s l i g h t random d i s t r i b u t i o n , tendency to form aggregates of grains but c l e a r l y o u t l i n e d . -173-Microscopic: Grain-size • Plagioclase (An33) (An 24) 45% Orthoclase 20% 5.34 X 3.22 mm Quartz 25% 1.37 . X 1.84 mm B i o t i t e 5% 1.23 X 0.55 mm 1.14 X 1.18 mm Hornblende < 5% Sphene trace 0.17 X 0.36 mm Apatite trace 0.05 X 0.05 mm Opaque • >2% 0.50 X 0.46 mm 0.17 X 0.17 mm Ch l o r i t e Texture: Somewhat p o r p h y r i t i c , p o i k i l i t i c as a r e s u l t of large i n t e r -s t i t i a l masses of orthoclase. Plagioclase shows normal zoning, s e r i c i t i c a l t e r a t i o n . Quartz i s anhedral i n t e r s t i t i a l with strained e x t i n c t i o n . Mafic b i o t i t e and hornblende have p o i k i l i t i c texture and ragged o u t l i n e s . Sphene i s subhedral to euhedral. 54. K64-98-I Gump Lake, Mamit Lake Macroscopic: Mottled pink and l i g h t cream-grey, medium- to very coarse-grained, s e r i a t e / p o r p h y r i t i c . Quartz conspicuous. Orthoclase i n t e r s t i t i a l p o i k i l i t i c . Mafic 5%, hornblende less abundant than b i o t i t e , fine-/coarse-grained, f o l i a t e d . Unaltered. Microscopic: Plagioclase (An3i) • 35% Orthoclase 16% Quartz 40% B i o t i t e > 5% Hornblende 1%" Apatite trace Zircon trace Opaque > 1% S e r i c i t e Texture: Seriate texture to weakly p o r p h y r i t i c , very coarse quartz grains and aggregates. Plagioclase, subhedral, a l b i t i z e d margins, weak o s c i l l a t o r y zoning, some showing poorly developed micrographic texture with quartz. Portions of some grains extensively s e r i c i t -ized. Orthoclase anhedral, i n t e r s t i t i a l , p e r t h i t i c , s l i g h t l y p o i k i -l i t i c enclosing p l a g i o c l a s e . Quartz, i n t e r s t i t i a l , a few grains showing fractures and strained e x t i n c t i o n . B i o t i t e and hornblende, anhedral, weakly p o i k i l i t i c , enclosing quartz and p l a g i o c l a s e . Too coarse-grained to show f o l i a t i o n i n th i n s e c t i o n . -174-55. K64-91 Gump Lake, Mamit Lake Macroscopic: Mottled pink and l i g h t cream-grey, medium to very coarse-grained, se r i a t e to p o r p h y r i t i c . Quartz conspicuous 30%. Ortho-clase i n t e r s t i t i a l , p o i k i l i t i c . Mafic 5%, hornblende l e s s abundant than b i o t i t e , fine to coarse-grained, f o l i a t e d . Microscopic: Plagioclase 50% Orthoclase • 10% Quartz 30% B i o t i t e > 5% Hornblende 1% Apatite < 1% Zircon trace Opaque > 2% Ch l o r i t e Prehnite S e r i c i t e Texture: H o l o c r y s t a l l i n e , s e r i a t e / s l i g h t l y p o r p h y r i t i c , p o i k i l i t i c . Plagioclase subhedral/anhedral. Orthoclase anhedral, i n t e r s t i t i a l , p o i k i l i t i c . Quartz anhedral, i n t e r s t i t i a l , mottled e x t i n c t i o n . B i o t i t e , ragged i n t e r s t i t i a l , p o i k i l i t i c , enclosing small anhedral grains of pl a g i o c l a s e . Quartz, opaque and subhedral grains of ap a t i t e . Opaques are anhedral, predominantly magnetite. 56. K64-89 Gump Lake, Mamit Lake Macroscopic: Mottled pink and l i g h t cream-grey, medium- to very coarse-grained, seriate to p o r p h y r i t i c . Quartz conspicuous 35%. Ortho-clase i n t e r s t i t i a l , p o i k i l i t i c . Mafic 5%, hornblende less abundant than b i o t i t e , f i n e - to coarse-grained, f o l i a t e d . Microscopic: Plagioclase 50% Orthoclase 10% Quartz 35% B i o t i t e < 5% Hornblende <.1% Opaque > 1% Sphene trace Zircon trace Apatite trace Prehnite S e r i c i t e -175-C h l o r i t e Epidote Texture: H o l o c r y s t a l l i n e , s e r i a t e to s l i g h t l y p o r p h y r i t i c . Plagioclase subhedral/anhedral, o s c i l l a t o r y zoning, extensive but s e l e c t i v e s e r i c i t i c a l t e r a t i o n , trace epidote. Orthoclase, i n t e r s t i t i a l anhedral, p e r t h i t i c , weakly p o i k i l i t i c . Quartz anhedral, i n t e r -s t i t i a l , mottled e x t i n c t i o n . B i o t i t e , ragged i n t e r s t i t i a l , c h l o r i t i c p o i k i l i t i c texture enclosing opaques, minor quartz and trace of a p a t i t e . 57. K64-61 Bethlehem, Abbott Lake Macroscopic: L i g h t grey and cream, fine/medium-grained, scattered coarse-grained, s l i g h t l y p o r p h y r i t i c . Quartz f a i r l y conspicuous. Mafic 10%, b i o t i t e more abundant than hornblende, very f i n e - to c o a r s e — g r a i n e d , tendency to form aggregates of grains, p o i k i l i t i c hornblende, random d i s t r i b u t i o n . Microscopic: Plagioclase (An^y) 65% Orthoclase > 5% Quartz 20% Hornblende < 5% B i o t i t e > 5% Sphene < 1% Apatite trace Opaque 2% S e r i c i t e Epidote Texture: H o l o c r y s t a l l i n e , seriate/weakly p o r p h y r i t i c . P l a g i o c l a s e , subhedral, o s c i l l a t o r y zoning, s e r i c i t e and epidote a l t e r a t i o n i n s e l e c t i v e zones. Orthoclase, i n t e r s t i t i a l , anhedral. B i o t i t e and p o i k i l i t i c hornblende, ragged o u t l i n e , shows c h a r a c t e r i s t i c uneven d i s t r i b u t i o n . B i o t i t e has warped e x t i n c t i o n , c h l o r i t i c a l t e r a t i o n . 58. K64-186a Bethlehem, Skeena Property on north flank Gnawed Mountain Macroscopic: Mottled l i g h t grey, cream and pink, medium- to coarse-grained, p o r p h y r i t i c , quartz i n t e r s t i t i a l , f a i r l y conspicuous. Mafic 107o, hornblende approximately equal- to b i o t i t e , some tendency to form aggregates of grains, p o i k i l i t i c hornblende, uneven d i s -t r i b u t i o n . -176-Microscopic: Plagioclase (An37) 55% Orthoclase < 10% Quartz 25% Hornblende > 5% B i o t i t e > 5% Apatite trace Zircon trace Opaque (magnetite) 2% C h l o r i t e Epidote Texture: H o l o c r y s t a l l i n e , p o r p h y r i t i c . Plagioclase, subhedral, o s c i l l a t o r y zoning, s e r i c i t i c a l t e r a t i o n of selected zones, shows preferred o r i e n t a t i o n . Orthoclase anhedral i n t e r s t i t i a l , reddish brown a l t e r a t i o n . Quartz anhedral, i n t e r s t i t i a l , strained e x t i n c t -ion. Hornblende i r r e g u l a r anhedral. B i o t i t e , ragged, extensive c h l o r i t i c a l t e r a t i o n . 59. K63-102 Bethlehem, South shoulder of South Forge Mountain Macroscopic: L i g h t cream-grey, s l i g h t l y p o r p h y r i t i c , medium-grained with scattered coarse-grains. Mafic 10%, b i o t i t e greater amount than hornblende, fi n e to coarse-grained, hornblende has p o i k i l i t i c texture, unevenly d i s t r i b u t e d aggregates of grains. Microscopic: Grain-size Plagioclase (An42) 60% (4.11 X 1.56 mm (1.84 X 0.92 mm Quartz 20% (0.68 X 1.01 mm (1.37 X 2.99 mm Orthoclase 5% . (0.68 X 0.46 mm (0.55 X 1.28 mm B i o t i t e <10% (0.92 X 0.68 mm (1.84 X 1.61 mm Hornblende 5% (1.93 X 0.36 mm (0.08 X 1.14 mm Apatite trace 0.08 X 0.17 mm Sphene trace 0.26 X 0.36 mm Opaque (magnetite) < 5% (0.68 X 0.50 mm (0.22 X 0.22 mm C h l o r i t e 0.62 X 0.31 mm Epidote 0.28 X 0.31 mm -177-Texture: H o l o c r y s t a l l i n e , p o r p h y r i t i c . P l a g i o c l a s e , subhedral, o s c i l l atory zoning, weak preferred o r i e n t a t i o n . Quartz i n t e r s t i t i a l , anhedral. Mafics show a p o i k i l i t i c texture, tend to occur as aggregates of grains, uneven d i s t r i b u t i o n . 60. K63-115 Bethlehem, OK Mine Road south side of Highland V a l l e y Macroscopic: Mottled l i g h t grey and cream with s l i g h t p inkish t i n t , medium- to coarse-grained, somewhat p o r p h y r i t i c texture, most noticeable i n mafics. Mafics 5 to 10%, hornblende greater amounts than b i o t i t e , wide v a r i a t i o n i n grain size from l e s s than 1 mm to greater than 6 mm. Hornblende p o i k i l i t i c . Microscopic: Grain-size Plagioclase (An36) 60% 1.93 x 0.92 mm Orthoclase 10% (0.68 x 0.68 mm (2.07 x 0.92 mm Quartz 20% (2.02 x 0.92 mm (2.07 x 1.84 mm Hornblende 2% (0.31 x 1.37 mm (4.11 x 1.47 mm B i o t i t e 5% (1.93 x 0.92 mm (0.46 x 0.55 mm Sphene < 1% 1.14 x 0.59 mm Apatite trace 0.30 x 0.10 mm Zircon trace (0.17 x 0.26 mm (0.04 x 0.26 mm Opaque (magnetite) 2% C h l o r i t e Carbonate (0.31 x 0.22 mm (0.15 x 0.05 mm Texture: H o l o c r y s t a l l i n e , p o r p h y r i t i c , p o i k i l i t i c . Plagioclase sub-hedral, weak o s c i l l a t o r y zoning, preferred o r i e n t a t i o n . Quartz, i n t e r s t i t i a l , few scattered included grains. Sphene, p o i k i l i t i c -a l l y encloses hornblende. Hornblende, subhedral, p o i k i l i t i c , en-c l o s i n g p l a g i o c l a s e , carbonate, has ragged o u t l i n e , uneven d i s t r i b t i o n . Orthoclase, i n t e r s t i t i a l , p o i k i l i t i c , encloses hornblende. 61. K63-189a-II . Bethlehem, South slope of Gnawed Mountain Macroscopic: Mottled pink and cream, medium- to coarse-grained, most grains 2-3 mm, quartz conspicuous subhedral,- i n t e r s t i t i a l . Mafic approximately 5%, b i o t i t e more abundant than hornblende, b i o t i t e euhedral, tendency to form aggregates of grains. -178-Microscopic: Grain-size Plagioclase (core An42 ) 60% (4.66 X 1.52 mm (margin An27) (1.61 X 0.78 mm Orthoclase 15% 4.66 X 6.96 mm Quartz 20% (1.37 X 1.84 mm (2.48 X 1.61 mm Hornblende 3% 0.55 X 0.92 mm B i o t i t e 2% 2.53 X 1.37 mm 0.68 X 0.92 mm Sphene ^ 1% (0.96 X 0.31 mm (0.36 X 0.73 mm Opaque (magnetite) > \% S e r i c i t e Texture: H o l o c r y s t a l l i n e , p o r p h y r i t i c , p o i k i l i t i c . Plagioclase sub-hedral, o s c i l l a t o r y zoning, trace micrographic texture, preferred, o r i e n t a t i o n . Orthoclase, forms large anhedral i n t e r s t i t i a l masses, p o i k i l i t i c encloses pl a g i o c l a s e , quartz and mafics. Quartz, an-hedral i n t e r s t i t i a l to p l a g i o c l a s e , mottled e x t i n c t i o n . B i o t i t e p o i k i l i t i c , encloses plagioclase and quartz, warped c r y s t a l s and ragged ends. Hornblende tends to form aggregates of f i n e grains, coarser grains have p o i k i l i t i c texture. 62. K64-203 Witches Brook, Ridge on south side of Witches Brook Macroscopic: Mottled l i g h t grey, cream, s l i g h t p i n k i s h t i n t , f i n e / medium-grained, scattered coarse-grained s l i g h t l y p o r p h y r i t i c . Quartz i n t e r s t i t i a l , not conspicuous. Mafic.10%, mafic o u t l i n e i n d i s t i n c t , hornblende>biotite, very f i n e - to coarse-grained, forms aggregates of grains. Massive. Microscopic; Plagioclase (An38) 50% Orthoclase 10% Quartz 30% Hornblende 5% B i o t i t e < 5% Augite < 1% Zircon trace Apatite trace Sphene trace Opaque < 1%: C h l o r i t e Carbonate -179-Texture: Hypidiomorphic granular/weakly po rphy r i t i c . P lag ioc lase , sub-hedral/euhedral, weak o s c i l l a t o r y zoning, preferred o r i e n t a t i o n . Orthoclase, i n t e r s t i t i a l , weakly p e r t h i t i c , p o i k i l i t i c , enclosing p lag ioc lase , hornblende and a p a t i t e . Quartz, i n t e r s t i t i a l , anhedr mottled e x t i n c t i o n . Maf ic , hornblende and b i o t i t e , both s l i g h t l y p o r p h y r i t i c , occurs as aggregates of f ine g ra ins , ragged o u t l i n e , associated with opaques. 63. K64-105-I Witches Brook, East f lank of Gypsum Mountain Macroscopic: Mottled l i g h t grey and p ink ish cream, f i n e - to medium-grained. Quartz i n t e r s t i t i a l , not conspicuous. Scattered sphene. Mafic less than 10%, amount of hornblende greater than or equal to b i o t i t e , very f i n e - to f ine -g ra ined , some tendency to form aggreg-ates of g ra ins , out l ine rather i n d i s t i n c t , randomly disseminated. Massive. Trace cha lcopyr i te . Microscopic : Gra in -s i ze ! . P lagioc lase 40% Orthoclase 20% Quartz 25% B i o t i t e < 5% Hornblende 5% Sphene 2% Opaque (magnetite, trace chalcopyr i te) >1% S e r i c i t e Texture: Hypidiomorphic, granular . P lag ioc lase , subhedral, normal zoning, very weak preferred o r i e n t a t i o n . Orthoclase, i n t e r s t i t i a l p o i k i l i t i c . Quartz, i n t e r s t i t i a l , p o i k i l i t i c . Sphene, anhedral i n t e r s t i t i a l , i n c lose assoc iat ion with hornblende. Mafics tend to be f ine -g ra ined , i r regu lar anhedral , form aggregates of g ra ins . 64. K63-216a Witches Brook, 1 mile north of Dot Lake ,3.22 X 2.07 mm 0.68 X 2.86 mm 1.88 X 0.96 mm 1.37 X 1.84 mm 2.07 X 0.92 mm 0.73 X 0.92 mm 0.92 X 1.84 mm 2.76 X 1.84 mm 0.22 X 0.31 mm 0.36 X 0.92 mm 0.46 X 1.47 mm 0.96 X 2.07 mm 1.28 X 0.87 mm 0.92 X 2.07 mm Macroscopic: L ight cream-grey, mottled p ink, f i n e - to medium-grained, -180-most grains 1 to 2 mm, quartz not conspicuous. Mafic 10%, b i o t i t e equal to hornblende f ine -g ra ined , occurs as aggregates of grains with i n d i s t i n c t o u t l i n e . Microscopic : P lagioc lase ( A n ^ core (An23 margin) 40% Orthoclase 15% Quartz . 30% B i o t i t e 5% Hornblende 5% Augite trace Sphene trace Apatite trace Opaque (magnetite) < 5% Prehnite? Chlor i te Epidote Grain '4.37 x ,1.37 x '2.53 x ,6.96 x :o.96 [2.07 [1.37 :i.6i Cl .47 [0.13 0.13 [0.42 x [0.09 x - s i z e .56 mm . 55 mm .37 mm .30 mm . 18 mm-,37 mm .31 mm . 73 mm . 26 mm .50 mm .36 mm . 68 mm . 55 mm '0.36 x 0.26 mm ,,0.13 x 0.13 mm Texture: H o l o c r y s t a l l i n e , weak p o i k i l i t i c , p o r p h y r i t i c . P lagioc lase subhedral, normal zoning, weak preferred o r ientat ion of p lagioc lase phenocrysts. Quartz i n t e r s t i t i a l , anhedral, s t ra ined e x t i n c t i o n . Mafic occurs as aggregates of f ine gra ins , b i o t i t e grains warped. 65. K64-111 Witches Brook Macroscopic: Mott led cream and l i g h t grey, f i ne -g ra ined , quartz not conspicuous. Mafic less than 10%, b i o t i t e greater amounts than hornblende, tendency to form aggregates of g ra ins , f i n e - g r a i n e d . Microscopic : Gra in -s i ze Plagioc lase (An 35) 45% (4.66 x 2.30 mm (1.37 x 0.59 mm Orthoclase 15% (0.96 x 2.76 mm \3.68 x 1.61 mm Quartz 25% 0.68 x 0.83 mm B i o t i t e 5% 1.37 x 0.68 mm Hornblende * 5% (0.46 x 0.50 mm (1.37 x 0.92 mm Sphene <• 1% . 1.23 x 0.42 mm Zircon trace 0.31 x 0.08 mm - 1 8 1 -Apatite trace Opaque 17o S e r i c i t e Chlor i te Texture: H o l o c r y s t a l l i n e , weak p o r p h y r i t i c , P lag ioc lase euhedral to subhedral, normal zoning, weak preferred o r i e n t a t i o n , Orthoclase, i n t e r s t i t i a l , anhedral. Quartz, anhedral granular . Mafics show some tendency to form aggregates of gra ins . B i o t i t e warped g ra ins . Hornblende s l i g h t l y p o i k i l i t i c texture. 66. K64-102 Witches Brook, Broom Creek Macroscopic: Mottled cream and l i g h t grey, s l i g h t p ink ish t i n t , medium-grained with scattered coarse-grained. Quartz not conspicuous, i n t e r -s t i t i a l . Mafic 107., ser iate very fine-/medium with scattered coarse-grained, hornblende more abundant than b i o t i t e , tends to form, aggregates of gra ins , random d i s t r i b u t i o n . Microscopic : Gra in -s i ze Plagioc lase 45% (1.42 x 0.42 mm (2.02 x 1.01 mm Orthoclase 20% 0.92 X 0.50 mm Quartz 25% (1.09 X 0.96 mm (1.65 X 0.83 mm Hornblende < 5% (1.18 X 0.83 mm (0.50 X 0.64 mm B i o t i t e 5% (0.83 X 1.33 mm (0.64 X 0.31 mm Sphene < 1% 1.09 X 0.68 mm Opaque 2% 0.36 X 0.46 mm S e r i c i t e Chlor i te Texture: Hypidiomorphic granular . P lagioc lase subhedral, trace micro-graphic texture, normal zoning, weak preferred o r i e n t a t i o n . Ortho-c l a s e , i n t e r s t i t i a l , p o i k i l i t i c , encloses quartz and p lag ioc lase . Quartz i n t e r s t i t i a l , anhedral, strained e x t i n c t i o n . Sphene euhedral and i n t e r s t i t i a l anhedral some enclosing quartz . Mafics have ragged o u t l i n e s , b i o t i t e has a warped e x t i n c t i o n , hornblende has a p o i k i -l i t i c texture. 67. K63-171 Witches Brook, Powerline access road west of Gump Lake Macroscopic: Mottled pink and l i g h t grey, fine-/medium-grained, scattered coarse-grained, s l i g h t l y po rphy r i t i c . Mafic 10-15%, hornblende - 182 -greater amounts than b i o t i t e , f i ne -g ra ined , forming aggregates of g ra ins . , Mic roscop ic : P lagioc lase Orthoclase Quartz B i o t i t e Hornblende Augite Opaque Sphene Zircon Epidote S e r i c i t e Carbonate Gra in -s i ze (An 3 7 core) 50% ( (An£4 margin) ( 10% £ 25% ( 5% < 5% trace 2% trace trace trace 0.92 2.90 4.66 2.76 3.13 2.30 0.50 0.55 0.55 0.08 0.83 0.17 x 2.39 mm x 1.01 mm x 1.84 mm x 2.30 mm x 1,37 mm x 2.53 mm x 0.68 mm x 0.83 mm x 0.17 mm x 0.13 mm x 0,64 mm x 0,26 mm Texture: Hypidiomorphic/porphyrit ic. P lag ioc lase , poorly developed o s c i l l a t o r y zoning, a l b i t i z e d margins. Orthoclase i n t e r s t i t i a l , forming large p o i k i l i t i c masses enclosing p lag ioc lase , quartz and maf ics . 68. K64-42 Witches Brook, North side of Highland Val ley on south f lank of Cinder H i l l Macroscopic: Mottled tan-cream and l i g h t grey, fine-/medium-grained, quartz not conspicuous. Mafic 107., hornblende greater amounts than b i o t i t e , forms aggregates of grains with random d i s t r i b u t i o n . Microscopic : P lagioc lase (An38) 40% Orthoclase 20% Quartz 25% Hornblende > 5% B i o t i t e 5% Sphene < 1% Grain [3.90 x 1 (1.37 x 0 0.92 (1.37 x 1.47 x (0.92 x 1.93 x (0.73 x 1.01 (0.64 0.59 (0.26 - s i z e -,37 mm .64 mm .92 mm ,37 mm . 61 -mm . 92 mm .59 mm .09 mm .73 mm .73 mm .01 mm ,31 mm - 1 8 3 -Apati te trace Opaque 1% 0.08 x 0.08 mm Chlor i te S e r i c i t e Texture: Hypidiomorphic, granular, s l i g h t l y p o i k i l i t i c . Micrographic texture, intergrowth of a l b i t e and quartz. Orthoclase i s i n t e r -s t i t i a l , s l i g h t l y p o i k i l i t i c . Quartz i s anhedral, i n t e r s t i t i a l showing strained e x t i n c t i o n . Mafics tend to form aggregates of g ra ins . 69. K64-28a Witches Brook, Foot Lake northeast end of Highland Val ley Macroscopic: Mottled pink and l i g h t to medium grey with s l i g h t l y greenish t i n t , fine-/medium-grained. Quartz i s not conspicuous. Mafic 10%, hornblende greater amounts than b i o t i t e , forms aggreg-ates of grains with random d i s t r i b u t i o n . Microscopic : Plagioclase (An42> 407. Orthoclase 25% Quartz 25% . Hornblende < 5% . B i o t i t e 5% Sphene trace Opaque (magnetite) < 2%, Epidote Chlor i te S e r i c i t e Texture: H o l o c r y s t a l l i n e , f a i r l y equigranular except for scattered plagioclase phenocrysts and scattered large i n t e r s t i t i a l patches of p o i k i l i t i c K feldspar enclosing p lag ioc lase . P lagioc lase shows preferred o r i e n t a t i o n . Strong a l t e r a t i o n . 70. K63-39 Witches Brook, Southwest f lank of South Forge Mountain Macroscopic: Mottled l i g h t grey and p ink ish cream, medium- to coarse-grained, most grains 1-3 mm, f a i r l y abundant disseminated sphene. S l i g h t l y porphyr i t i c texture most evident i n mafic minera ls . Mafic 5-107., hornblende less abundant than b i o t i t e ; hornblende has a p o i k i l i t i c texture. -184-Gra in -s i ze (2.07 x 0.46 mm .3.45 x 1.61 mm 4.66 mm .6,50 mm k3.22 x 2.07 mm ,3.90 x 3.90 mm ^ . 4 6 x 1.61 mm .3.68 x 2.07 mm ( 0.55 x 0.26 mm .0.68 x 0.36 mm ^0.08 x 0.08 mm .0.23 x 0.09 mm S e r i c i t e Epidote Chlor i te Texture: Close packed coarse-grained subhedral/anhedral phenocrysts i n a f ine -gra ined groundmass. Orthoclase forms large i n t e r s t i t i a l masses p o i k i l i t i c a l l y enclosing p lagioc lase and maf ics , s l i g h t l y p e r t h i t i c . B i o t i t e grains warped, some c h l o r i t i c a l t e r a t i o n . Horn-blende shows p a r t i a l replacement by quartz. I n t e r s t i t i a l hornblende much coarser -grained, po rphy r i t i c , p o i k i l i t i c . 71 . K63-222 Witches Brook (Bethlehem "Gran i te" ) , Bethlehem property Macroscopic: Mottled pink and white, f i ne -g ra ined , most grains 1 to 2 mm. Mafic approximately 57,, b i o t i t e greater amounts than hornblende, less than 1 to 2 mm, fine-/medium-grained evenly disseminated. Massive. Microscopic : P lagioc lase 30% Orthoclase 30% Quartz 35% B i o t i t e < 5% Hornblende trace Apat i te trace Zircon trace Opaque < 1% Chlor i te Texture: Hypidiomorphic granular . P lagioc lase normal zoning, weak pre -ferred o r i e n t a t i o n . Orthoclase i n t e r s t i t i a l , p o i k i l i t i c , encloses quartz, b i o t i t e and plagioclase but does not form large masses, p e r t h i t i c . Microscopic : P lagioc lase (An4i) 25% Orthoclase 25% Quartz 40% B i o t i t e , 5%, Hornblende 2% Apati te trace Sphene trace Opaque (magnetite) 1% -185 72. K64-17 Witches Brook, Spatsum Macroscopic: Mottled pink and l i g h t grey, flecked with cream-green, epidote a l t e r a t i o n . Quartz i n t e r s t i t i a l granular. Mafic 5%, b i o t i t e , very f i n e - / f i n e - g r a i n e d , scattered medium-grained, tends to form small randomly d i s t r i b u t e d aggregates of grains. Microscopic: Grain-size Plagioc lase : 30% (1.84 X 1.18 mm (1.84 X 1.61 mm Orthoclase ; 25% (0.92 X 1.01 mm 1 (0.87 X 1.37 mm Quartz 40% (1.01 X 1.18 mm (0.92 X 0.59 mm B i o t i t e 2% 0.42 X 0.98 mm 0.42 X 0.26 mm Zircon trace Opaque (magnetite) <1% Chlor i te Epidote S e r i c i t e Texture: Hypidiomorphic, granular . P lag ioc lase , anhedral/subhedral, p a r t i a l replacement by quartz, extensive s e r i c i t i c and traces epidote a l t e r a t i o n . Orthoclase anhedral, p e r t h i t i c . Quartz an-hedra l , granular . B i o t i t e , anhedral, s l i g h t l y shredded, forming c lus te rs of g ra ins . 73. K63-231 Bethsaida, Ridge south of C a l l i n g Lake Macroscopic: Mottled cream, l i g h t grey, pink, coarse- to very coarse-grained, p o r p h y r i t i c . Quartz 30% very coarse-grained i n t e r s t i t i a l p o r p h y r i t i c . Mafic less than 5%, b i o t i t e greater amount than horn blende. B i o t i t e occurs i n c h a r a c t e r i s t i c very coarse-grained euhedral phenocrysts. Hornblende p o i k i l i t i c . Microscopic : Gra in -s i ze P lag ioc lase (An34) 45% (4.11 x 1.52 mm (.1.84 x 1.37 mm Orthoclase 15% (4.66 x 2.07 mm (3.22 x 2.30 mm Quartz 30% 8.77 x 5.34 mm Hornblende 1% 2.12 x 1.05 mm B i o t i t e 5% 1.84 x 0.68 mm Opaque < 1% Sphene < 1% 0.55 x 0.68 mm -186 -Apatite < 1% (0.13 x 0.13 mm (0.31 x 0.36 mm Zircon trace 0.18 x 0.18 mm Epidote Ch lor i te Texture: P o r p h y r i t i c , large subhedral to anhedral quartz g ra ins , eu-hedral p lagioclase i n a f ine -gra ined groundmass of quartz , p l a g i o -clase and large i n t e r s t i t i a l c l o t s of p e r t h i t i c or thoclase. P l a g i o -clase has o s c i l l a t o r y zoning. Orthoclase i s anhedral i n t e r s t i t i a l , p e r t h i t i c , s l i g h t l y p o i k i l i t i c . Quartz i s subhedral, i n t e r s t i t i a l to p lag ioc lase , shows strained e x t i n c t i o n . B i o t i t e euhedral pheno-c r y s t s , s l i g h t p o i k i l i t i c texture. 74. K63-187* Gnawed Mountain Porphyry, Gnawed Mountain Macroscopic: Mottled cream, l i g h t grey, minor p ink, medium-/very coarse-grained, 30% conspicuous subhedral/anhedral quartz phenocrysts. Mafic less than 57«, b i o t i t e greater amounts than hornblende, i n th is specimen i s f ine -g ra ined , subhedral, random d i s t r i b u t i o n . Microscopic : P lagioc lase Orthoclase Quartz B i o t i t e Opaque Ch lor i te S e r i c i t e Texture: P o r p h y r i t i c , very coarse-grained phenocrysts of quartz and p lagioc lase in a very f ine -gra ined anhedral groundmass of quartz , p lag ioc lase , i n t e r s t i t i a l orthoclase. P lagioc lase shows o s c i l l a t o r y zoning. Orthoclase i s i n t e r s t i t i a l , clouded with red-brown a l t e r a -t ion with trace of s i e v e - l i k e texture i n margins inc lud ing very f ine -gra ined granular quartz . B i o t i t e f i ne -g ra ined , c h l o r i t i c a l t e r a t i o n . -187-APPENDIX I I I ; SUMMARY OF STEREOGRAM ANALYSIS Jo i n t Patterns of A l l Phases on Each Sub-Area ' Stereograms for a l l j o i n t s within each sub-area are summarized as I follows (Figure 28, a-1 to a-7). Most poles of j o i n t s occur near the margins of the stereograms representing v e r t i c a l or steeply dipping j o i n t s which may s t r i k e i n any d i r e c t i o n . Continuous concentrations of the poles of j o i n t s , however, indicate that most j o i n t s trend from northeasterly to northwesterly. The continuous change i n trend i s less evident i n the North-central sub-area and only two concentrations of poles of j o i n t s i n d i c a t i n g e a s t e r l y and nort h e r l y s t r i k e s are obvious i n the Southwest sub-area. The Northwest, North-central, Central, and South-central sub-areas have small concentrations of poles of j o i n t s which represent northeast trends with moderate northwesterly dips. There i s , i n general, a s i m i l a r i t y of major j o i n t systems. J o i n t Patterns i n S p e c i f i c Phases within Each Sub-Area Stereograms for poles of j o i n t s i n s p e c i f i c phases within each sub-area are summarized as follows (Figure.28, b-1 to h-7). -188 -Hybr.id Phase (Figure 28, b l - b7) Northwest and Southeast sub-areas, where the most j o i n t a t t i tudes were measured for Hybrid phase, show a f a i r l y continuous range of s t r i kes from northeaster ly to northwesterly with v e r t i c a l or steep d i p s . In the Northwest sub-area, however, there i s a greater range of s t r i k e s . Northwest, Northeast and Southeast sub-areas have concentrations of j o i n t poles representing jo in ts s t r i k i n g northeaster ly with moderate northwesterly d ips . Guichon Var iety (Figure 28, c l - c7) Northeast and Southeast sub-areas both show strong systems nor th -easter ly s t r i k i n g v e r t i c a l j o i n t s . Northeast, Northwest and Central sub-areas have norther ly s t r i k i n g j o i n t systems. Northwest, Cent ra l , South-central and Southeast sub-areas have strong northwesterly s t r i k i n g systems. Nor th -cent ra l , Northeast and Southwest sub-areas have concentra-t ions ind ica t ing northeaster ly j o i n t s t r i kes with northwesterly d i p s . Northeast and Southwest sub-areas show a greater range of s t r i k e s prob-ably because a greater number of j o in t s were measured for Guichon var -i e t y i n these sub-areas. Chataway Var iety (Figure 28, d l - d7) Northwest, Nor th -cent ra l , Northeast, Southwest, South-central and Southeast sub-areas have steeply dipping to v e r t i c a l , westerly to nor th -westerly s t r i k i n g j o i n t systems. Stereograms for Northeast and South-east sub-areas have concentrations of poles of j o i n t s representing -189 -systems of northeaster ly s t r i k i n g , gently northwesterly dipping j o i n t s . Gump Lake Phase (Figure 28, e7) The stereogram of poles of j o in t s for the Gump Lake phase i n South-west sub-area shows three major j o i n t systems, s t r i k i n g northeaster ly by norther ly with steep westerly d i p , s t r i k i n g northwesterly with steep northeaster ly dip and s t r i k i n g easter ly with gentle southerly d i p . Gump Lake phase occurs i n no other sub-area. Witches Brook Phase (Figure 28, f 6 , f7) Jo in t systems i n Witches Brook of Southeast and South-central sub-areas s t r i k e northeaster ly and dip steeply northwesterly, southeasterly or are v e r t i c a l . The Southeast sub-area, i n which the most j o i n t s were measured, also has northwesterly to westerly s t r i k i n g j o i n t systems which dip steeply northeaster ly or southwesterly. Bethlehem Phase (Figure 28, g2, g4) Stereograms for North -centra l and Central sub-areas indicate strong / j o i n t systems s t r i k i n g northwesterly with v e r t i c a l or steep southwesterly . d ips . Two concentrations of poles of j o in t s on the stereogram for the North -centra l sub-area indicate northeaster ly s t r i kes with moderate to steep southeasterly and northwesterly d ips . Bethsaida Phase (Figure 28, h4) The Bethsaida phase crops out only i n the Central sub-area. The margin of the stereogram i s rimmed.with poles of j o in t s ind ica t ing -190 -v e r t i c a l to steeply dipping j o i n t systems trending i n any d i r e c t i o n . Major concentrations, however, show predominant s t r ikes are nor ther ly , wester ly , northwesterly and northeaster ly . As a r e s u l t of the r e l a t -i v e l y large number of j o i n t systems measured for Bethsaida i n th is sub-area, less wel l developed, more gently dipping systems become evident . 1963-64 Field Season B y - K . Northcote Drawn by - H ^ t . SYMBOLS CONTACT B E T W E E N PHASES CONTACT B E T W E E N VARIET IES BRECCIA AAA > 205+8 my K/A AGE DATE To Savona L E G E N D VOLCANICS POST-INTRUSIVE ROCKS KAMLOOPS GROUP KINGSVALE GROUP SPENCES BRIDGE GROUP MIDDLE/UPPER JURASSIC INTRUSIVE ROCKS GNAWED MOUNTAIN PORPHYRIES BETHSAIDA PHASE WITCHES BROOK PHASE VARIETY A VARIETY B VARIETY BETHLEHEM PHASE GUMP LAKE PHASE LE ROY "GRANODIORITE" HIGHLAND VALLEY PHASE HYBRID PHASE PRE-INTRUSIVE ROCKS NICOLA GROUP CACHE CREEK GROUP 50° 30' CHATAWAY VARIETY GUICHON VARIETY I Mi le FIGURE 6 To Shulus 3 Merritt Craigmont Mines Ltd / 1 V / A x n 5-t o <3 y E p o O /("/ /A \ x v r A \ * \-\56 J | V i / / A ^ ; 1 j , M y \ / o o o CVI / As. \ / \ / / / \ STRUCTURE OF THE GUICHON CREEK BATHOLITH By-K.E.Northcote Drawn *A-C N I X \ \ \ & • / I l i \ \ \ \ \ A X A- \ / \ A f X / 4. ^ / J A Al > x w A J"so X 7 So . \ X A / ,<^y> ApSX 3^ J A Q< \ \ f \ T ^ ^ ^ ^ / 1 \ I T \ ^ 8 0 70 Bethlehem Copper / i~^--J \ J .Corp. ^ . y " / , V 7 ^ J: / / X / v\ \ y% x x A \ \ \ 50°30* \ \ v \ \ \ i \ \ \ \ •i K \ . \ \ \ / * S / \ QKMine" / ••• ^ V 0 V \ \ v /I7/ \ / \ \ /Skeena \ \ \ \ \ > l 1 A / 7 .-go \ \ \ \ / \ \ \ V f I \ \ It" f IS r ,^ <JL\ \ ' f e y * \ \ \ \ \ 9 • « \ 7S ^Uf /V'v-.. i y A / So — • / — i H / V 11! V$1 \ •1 \ 5o4 \ s \ \ _ 4 0 \ \ \ " • \ . . . \ \\ \ / / I «0 LEGEND Bedding Planes Joint Planes Shear Planes Foliation \ \ \ 7 « - - . ^ V So / / / v \ \ \ \ \ ^ \ J ) \ To £5 j Al ) A^\TH . . - . . no 1 1» \ \ Geologic Contacts Air Photograph Lineaments Faults 8 * \ " --^sSs ; . . . " ) I i- > w ^ # ^ A A - . , SO 7—J -«<5 7 ?=A^ \ • xv # A \ A ^ X Scale I Mile Figure 26 SO v 2 » 8 0 J N t \ , A A t s. AWMCCmAgua K/A AGE DETERMINATION ® k n e u r n K • f o i - <xv\al<fSeS sepixt-aiecf Unfcnou>n 6a* 6 & o 6 % o 6 6 Tbtai - 0-01161% KTOTAL. 40 K in sample Shxftdard o f c o " « « t r - f i « /7ame Photometer {/.outer m»n u.«k«o>*»'} Fas/on - V - V . . ^ ^ Sp/lfE-flrf- / ^ o * Calibration S^s/t**l /^ocfc Sample / / o w blende Capture /0.95% -a Ca Amount of T o T O t - we « S t t c e c / adJm<j Knou>n «moc<*£ of 28/q"sp?ke" -/b s « / s ^ 4 0 /? 2.95". P a n e l t " 8 ^ £hacftc«jey,ic J •Me £ O? **>K \H 1N& SAMPLE, ancf -tAe. a.ynou.rxiC of ft * ir\-fke SAMPLE. ) -tint AYE O£ - ^e HACK CAN be. CA.(CU.(A-R-EJ • Mass Spe.cirome.hzr 6/secl In ft Analyses \ r ^ u r e 25 STEREOGRAMS OF POLES OF JOINTS PHASE SUBAREAS NORTHWEST NORTH-CENTRAL NORTHEAST CENTRAL SOUTHWEST SOUTH-CENTRAL SOUTHEAST ALL PHASES HYBRID 170 points 1% Contour interval 56 points 1% Contour interval A-3 66 points 1% Contour interval 1% 67 points 1% Contour interval A-5 33 points 4% Contour interval 95 points 1% Contour interval 399 points 1% Contour interval 5% 1% GUICHON VARIETY 5% 1% CHATAWAY VARIETY o O 3% GUMP LAKE WITCHES BROOK BETHLEHEM BETHSAIDA 

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