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Geology and genesis of zinc-lead deposits within a late proterozoic dolomite, Northern Baffin Island,… Olson, Reginald Arthur 1977

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GEOLOGY AND GENESIS OF ZINC-LEAD DEPOSITS WITHIN A LATE PROTEROZOIC DOLOMITE, NORTHERN BAFFIN ISLAND, N.W.T. by REGINALD ARTHUR OLSON B.Sc, University of B r i t i s h Columbia, 1968 M.Sc, University of Western Ontario, 1971 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES (Department of Geological Sciences) We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA January, 1977 © Reginald Arthur Olson, 1977 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of Brit ish Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of Brit ish Columbia 20 75 Wesbrook Place Vancouver, Canada V6T 1W5 ABSTRACT Economically important M i s s i s s i p p i Valley type zinc-lead deposits e x i s t i n a l a t e Proterozoic dolomite, the Society C l i f f s Formation, at north B a f f i n Island, D i s t r i c t of Franklin, N.W.T., Canada. The Society C l i f f s Formation ranges from 1,000 to 2,000 feet i n thickness and i s underlain by up to 2,000 feet of black, organic-rich shale, the A r c t i c Bay Forma-t i o n , and overlain by either black shale and limestone of the Vi c t o r Bay Formation or by red, f i n e - to coarse-grained c l a s t i c rocks of the Strathcona Sound Formation. Disconform-i t i e s e x i s t between each of the formations. Society C l i f f s Formation has undergone at le a s t four temporally d i s t i n c t episodes of k a r s t i f i c a t i o n since i t s deposition. The most important karst episode, with respect to the formation of the zinc-lead deposits, occurred during the h i a t a l i n t e r v a l between the deposition of the V i c t o r Bay Formation and the deposition of the Strathcona Sound Formation. During t h i s h i a t a l i n t e r v a l a holokarst developed i n Society C l i f f s Formation and a large integrated cave system of the Mammoth Cave-Flint Ridge Cave System type was formed; i . e . long, nearly horizontal, tubular passages were formed during i n i t i a l periods of base-level s t a b i l i z a t i o n , followed by the development of sub-vertical canyons beneath the tubes when the base-level dropped. After t h i s karst episode the Society C l i f f s Forma-t i o n was deeply buried and the cave system was p a r t i a l l y or i i i completely f i l l e d with sulphide and carbonate minerals. The zinc-lead deposits are characterized by banded structure which comprises p y r i t e , r e l i c t marcasite, sphalerite and galena interlayered with sparry dolomite. The zinc-lead deposits con-t a i n several sedimentary structures that were formed by a chemical deposition-chemical corrosion process. These include c r o s s - s t r a t i f i c a t i o n , c u t - a n d - f i l l and onlap. Onlap indicates the paleocaves were f i l l e d from the f l o o r up. The meteoric waters which formed the caves did not form the zinc-lead deposits because the temperature of ore deposition was between 200°C and 150°C, the calculated oxygen isotope composition of the ore f l u i d i s +12.8 per m i l , and mineral s t a b i l i t y and i s o t o p i c data indicate the oxygen fugacity decreased during ore deposition. The sulphide sulphur isotope composition of the zinc-lead deposits has a r e l a t i v e l y narrow range about +26 per mil, s i m i l a r to that of sulphate evaporite (+23.7 per mil) which e x i s t s l o c a l l y within the Society C l i f f s Formation. Lead isotope data indicate the lead i n the deposits was derived by at l e a s t a two-stage process from a source with a uniform uranium-thorium r a t i o . The ore f l u i d and contained metals are postulated to have been derived from the A r c t i c Bay Formation during a late-stage dewatering of the shale. Sulphide deposition may have been caused by the chemical reduction of sulphate which existed i n the ore f l u i d when the ore f l u i d entered hydrocarbon-f i l l e d caves. The hydrocarbons were probably expelled from the A r c t i c Bay Formation shale during an e a r l i e r stage of thermal metamorphism and dewatering. i v PREFACE "No simple model of o r i g i n i s l i k e l y to explain a l l or even most metalliferous deposits — we must become  accustomed to d i v e r s i t y . " (White, 1973, p. 862). V TABLE OF CONTENTS PAGE C e r t i f i c a t e of Examination ^ ABSTRACT ± ± PREFACE i v TABLE OF CONTENTS v LIST OF TABLES LIST OF FIGURES x i LIST OF PLATES x i i i ACKNOWLEDGMENT x v CHAPTER I - INTRODUCTION 1.1 Location 1 1.2 Topography and Climate * i 1.3 History 2 1.4 Statement of Problem 4_ CHAPTER II - STRATIGRAPHIC RELATIONSHIPS AND STRUCTURE 7 II.1 Proterozoic Rocks 7 Eqalulik Group 7 Nauyat Formation 7 Adams Sound Formation 8 Uluksan Group 8 A r c t i c Bay Formation 8 Society C l i f f s Formation 12 Vic t o r Bay Formation 22 Strathcona Sound Formation -Athole Point Formation 24 Elwin Formation 26 Gabbro and Diabase Dykes 2 7 v i PAGE I I . 2 P h a n e r o z o i c Rocks 28 A d m i r a l t y Group 28 S h i p P o i n t F o r m a t i o n 29 B r o d e u r Group 30 E c l i p s e Group 31 I I . 3 R e g i o n a l S t r u c t u r e 32 I I . 4 N a n i s i v i k A r e a 33 I I . 5 Hawker C r e e k A r e a 38 I I . 6 D i s c u s s i o n 42 U l u k s a n Group Age 42 D i a s t r o p h i s m and T e c t o n i c a l l y A c t i v e A r e a s D o l o m i t i z a t i o n o f S o c i e t y C l i f f s F o r m a t i o n CHAPTER I I I - MINERAL DEPOSITS 111.1 M a s s i v e Z i n c - L e a d - D e p o s i t s M i n e r a l o g y and F a b r i c S u l p h i d e M i n e r a l s N o n - s u l p h i d e M i n e r a l s F a b r i c C o n t a c t R e l a t i o n s h i p s D i s t r i b u t i o n , T r e n d , Shape and S u l p h i d e V a r i a t i o n o f D e p o s i t s N a n i s i v i k A r e a Hawker C r e e k A r e a C h r i s C r e e k and O t h e r A r e a s 111.2 F i s s u r e - F i l l O c c u r r e n c e s M i n e r a l o g y and F a b r i c 46 48 52 54 55 56 61 65 80 86 86 93 95 98 99 v i i PAGE Dis t r i b u t i o n and Spatial Relationship to Massive Zinc-Lead Deposits 101 111.3 Disseminated Sulphide Occurrences 102 111.4 Iron Oxide and Iron Hydroxide Deposits i n Society C l i f f s Formation 105 Mineralogy, Fabric and Size of Deposits 105 D i s t r i b u t i o n and Spatial Relationship to Massive Zinc-Lead Deposits 106 111.5 Discussion 108 K a r s t i f i c a t i o n of Society C l i f f s Formation 108 Karst Episode I - Formation of Breccia and Collapse Structures 108 Karst Episode II - Formation of an Integrated Cave System 116 Karst Episode III - Formation of Hematite Deposits 129 Karst Episode IV - Formation of Channels (Bogaz) 130 Mineral Deposits 133 Paragenesis 133 The Significance of Sulphide 'Polymorphs' 138 Formation and Significance of Mesoscopic Structures in, Massive Zinc-Lead Deposits 144 Pyrobitumen Within Sulphide Deposits 154 CHAPTER IV - FLUID INCLUSION AND ISOTOPIC STUDIES 155 IV.1 F l u i d Inclusion Studies 155 Results 157 IV.2 Isotopic Studies 160 Sulphur Isotopes 160 Results 165 v i i i PAGE Carbon and Oxygen Isotopes 166 Results 174 Lead Isotopes 180 Results 188 IV.3 Discussion 192 Age of the Zinc-Lead Deposits 192 Source of the Elements i n the Zinc-Lead Deposits 194 Source of the Sulphur 194 Source of the Metals 203 Source of the Carbon and Oxygen i n Carbonate and Gypsum; Carbon and Oxygen Isotopic Composition of the Ore F l u i d 2 09 Physical-Chemical Constraints on the Ore F l u i d 217 S a l i n i t y of the Ore F l u i d 217 Temperature of the Ore F l u i d 218 Constraints Imposed by the Mineral Assemblage and by the Sulphur Isotope and Carbon Isotope Data 225 The Probable Cause of Ore Deposition 244 Genetic Model for the Generation of Hydrocarbons and the Ore F l u i d 25 3 CHAPTER V - SUMMARY, CONCLUSIONS, RECOMMENDATIONS 268 V . l Summary and Conclusions 268 V.2 P r i n c i p a l Contributions of This Research 278 V.3 Recommendations 281 REFERENCES 286 IX APPENDICES PAGE Appendix I A n a l y t i c a l Methods and Data Tabulation 324 Appendix II Summary of Modern Views on Karst 336 Appendix III Summary' of Geochemical and Geophysical Surveys That Bear on Ore Genesis 359 VITA X LIST OF TABLES TABLE PAGE I TABLE OF FORMATIONS 9 II STRATIGRAPHIC SECTION, ELWIN INLET AREA 22 III AULACOGEN CHARACTERISTICS 4 9 IV IRON CONTENT OF ZINC SULPHIDES 60 V MOLE PER CENT CALCIUM IN SPARRY DOLOMITE AND SOCIETY CLIFFS FORMATION DOLOMITE 63 VI IRON, ZINC AND MANGANESE CONTENTS OF DOLOMITES 63 VII FABRIC VARIETIES WITHIN MASSIVE ZINC-LEAD DEPOSITS 68 VIII MANTO ELEVATIONS AND CROSS SECTIONAL AREA, NANISIVIK MAIN ORE ZONE 9 0 IX SUMMARY - CROSS SECTIONAL AREA, NANISIVIK MAIN ORE ZONE 91 X ORE METAL VARIATIONS, NANISIVIK MAIN ORE ZONE 93 XI KARST EPISODES, NORTH BAFFIN ISLAND 110 XII SULPHUR ISOTOPE RESULTS 167 XIII CARBON AND OXYGEN ISOTOPE RESULTS 175 XIV LEAD ISOTOPE RESULTS 18 7 XV THERMODYNAMIC REACTIONS AND LOG K OF REACTION 227 XVI SUMMARY OF THE PHYSICAL, CHEMICAL AND ISOTOPIC PROPERTIES OF THE BORDEN PENINSULA ZINC-LEAD DEPOSIT ORE FLUID 245 XI LIST OF FIGURES FIGURE PAGE 1 LOCATION. 3 2 MINERAL DEPOSITS AND GEOGRAPHIC LOCATIONS, NORTH BAFFIN ISLAND. Hof Oak JABX % -^ee^ET1" 3 GEOLOGY, BORDEN PENINSULA. WQJ^ Qo-b ' 4 GEOLOGY, NANISIVIK. 36 5 GEOLOGY, HAWKER CREEK. Ho-p Gx,bvAxflA % -POGKET— 6 SAMPLING AND GEOLOGY, TRENCH SH25-1, HAWKER CREEK, (^J^JXUMJLX . 7 GEOLOGY, TRENCH SH25-2, HAWKER CREEK. 12 NANISIVIK MAIN ORE ZONE, PLAN AND CROSS SECTIONS. 78 9 MODEL FOR FORMATION OF BRECCIA,. DOMES, BASINS AND FISSURES WITHIN SOCIETY CLIFFS FORMATION. 10 MODERN CAVE SHAPES. 11 SUMMARY OF PARAGENESIS WITHIN ZINC-LEAD DEPOSITS AT NORTH BAFFIN ISLAND. 12 REACTION PROGRESS DIAGRAMS. 13 FORMATION OF WURTZITE AND COEXISTING PYRITE OR MARCASITE. 114 119 134 135 143 14 15 16 SUMMARY OF FLUID INCLUSION F I L L I N G TEMPERATURES AND SULPHIDE SULPHUR ISOTOPE FRACTIONATION TEMPERATURES, NORTH BAFFIN ISLAND ZINC-LEAD DEPOSITS. 207 204 206 204 P b ^ ' / P b ^ VERSUS Pb""VPb ISLAND ZINC-LEAD DEPOSITS. P b 2 0 8 / P b 2 ° 4 VERSUS P b 2 0 6 / P b 2 ° 4 ISLAND ZINC-LEAD DEPOSITS. NORTH BAFFIN NORTH BAFFIN 159 190 191 17 SULPHUR ISOTOPE FRACTIONATION AMONG SULPHATE, HYDROGEN SULPHIDE AND SULPHIDE MINERALS. 197 X l l FIGURE 18 RANGE OF CARBON ISOTOPES IN NATURAL CARBONATE AND RELATED MATERIAL, AND IN CARBONATE FROM NORTH BAFFIN ISLAND. 19 RANGE OF OXYGEN ISOTOPES IN NATURAL CARBONATE AND RELATED MATERIAL, AND IN CARBONATE AND GYPSUM FROM NORTH BAFFIN ISLAND. 20 <5D VERSUS SO 1 8 IN NATURAL WATERS AND IN PALEO WATERS WHICH EXISTED AT NORTH BAFFIN ISLAND. 21 OXYGEN ACTIVITY - CARBON DIOXIDE ACTIVITY DIAGRAMS AT TEMPERATURES OF 250°C, 200°C AND 1.5 0°C. 2 2 OXYGEN ACTIVITY - SULPHUR ACTIVITY DIAGRAMS AT TEMPERATURES OF 250°C, 200°C AND 150°C. 2 3 OXYGEN ACTIVITY - pH DIAGRAM AT A TEMPERATURE OF 200°C. 24 OXYGEN ACTIVITY - pH DIAGRAM AT A TEMPERATURE OF 150OC. 25 BURIAL HISTORY OF EQALULIK GROUP AND ULUKSAN GROUP, BORDEN PENINSULA, NORTH BAFFIN ISLAND, 2 6 RECONSTRUCTION OF THE POSSIBLE GEOLOGICAL SETTING DURING FORMATION OF ZINC-LEAD DEPOSITS AT NORTH BAFFIN ISLAND. x i i i L I S T OF PLATES PLATE PAGE I . a A r c t i c Bay F o r m a t i o n o v e r l a i n by S o c i e t y C l i f f s F o r m a t i o n n e a r t h e h e a d o f Adams Sound. 11 I.b S o c i e t y C l i f f s F o r m a t i o n a t A t h o l e P e n i n s u l a . 11 I I . a R e g u l a r l y l a m i n a t e d a l g a l d o l o m i t e o f S o c i e t y C l i f f s F o r m a t i o n . 14 I I . b I n t e r b e d d e d r e g u l a r l y l a m i n a t e d a l g a l d o l o m i t e and d o l o l u t i t e o f S o c i e t y C l i f f s F o r m a t i o n . 14 I I I . a A n a s t o m o s i n g , cemented j o i n t s and c r a c k l e b r e c c i a w i t h i n S o c i e t y C l i f f s F o r m a t i o n . 19 I l l . b M o s a i c and c r a c k l e b r e c c i a g r a d i n g i n t o n o n -c o n f o r m a b l e and c o n f o r m a b l e r u b b l e b r e c c i a w i t h i n S o c i e t y C l i f f s F o r m a t i o n . 19 I V . a M o s a i c b r e c c i a and n o n c o n f o r m a b l e r u b b l e b r e c c i a w i t h i n S o c i e t y C l i f f s F o r m a t i o n . 20 IV.b R u b b l e b r e c c i a w i t h i n S o c i e t y C l i f f s F o r m a t i o n . 20 V S t r a t i g r a p h y a t E l w i n I n l e t a r e a . 2 3 VI F i s s u r e and b a s i n s t r u c t u r e s a t Hawker C r e e k . 4 3 V I I . a ' C h a n n e l s * (bogaz) a t Hawker C r e e k . 44 V l l . b ' C h a n n e l s ' (bogaz) a t Hawker C r e e k . 44 V I I I . a S u l p h i d e i n t e r l a y e r e d w i t h s p a r r y d o l o m i t e . 70 V I I I . b H o r i z o n t a l l y banded s u l p h i d e and s p a r r y d o l o m i t e f o r m i n g an o r e zone a b o u t 4 f e e t t h i c k . N a n i s i v i k main o r e zone. 70 IX C r o s s - s t r a t i f i e d , banded s t r u c t u r e i n P7 f a b r i c v a r i e t y o f p y r i t e i n t r e n c h SH25-1 a t Hawker C r e e k . 71 X.a C r o s s - s t r a t i f i c a t i o n w i t h i n i n t e r l a y e r e d s u l p h i d e and s p a r r y d o l o m i t e a t 1,700 N o r t h C r o s s - c u t , N a n i s i v i k main o r e zone. 75 X.b A l a r g e s c a l e example o f c r o s s - s t r a t i f i c a t i o n w i t h i n N a n i s i v i k main o r e zone. 75 xiv PLATE PAGE XI C r o s s - s t r a t i f i c a t i o n and corroded overlap structure in interlayered sulphide and sparry dolomite at Nanisivik main ore zone. 76 XII.a C u t - a n d - f i l l structure i n trench SH25-1 at Hawker Creek. Banded sphalerite and sparry dolomite (S3 fabr i c variety) is. overlain by banded pyrite (P7 fabr i c v a r i e t y ) . 77 XII.b C u t - a n d - f i l l structure in trench SH25-1 at Hawker Creek. Close-up of Plate XII.a. 77 XIII.a Sulphide breccia at 1,900 South Cross-cut, Nanisivik main ore zone. 79 XIII.b Sulphide s t a l a c t i t e s at Twin Lakes Creek pyr i t e zone. 7 9 XIII.c Close-up of sulphide s t a l a c t i t e s at Twin Lakes Creek py r i t e zone. 79 XIV.a Contact between northerly dipping, regularly laminated a l g a l dolomite of Society C l i f f s Formation and horiz o n t a l l y banded sulphide and sparry dolomite at 1,900 South Cross-cut, Nanisivik main ore zone. 8 2 XlV.b Contact between regularly laminated a l g a l dolomite of Society C l i f f s Formation and banded py r i t e and sparry dolomite i n trench SH25-2, Hawker Creek. 82 XV.a Termination of a small manto exis t i n g at 1,700 South Cross-cut, Nanisivik main ore zone. 89 XV.b Rounded termination of the small manto exis t i n g at 1,700 North Cross-cut, Nanisivik main ore zone. 8 9 XVI Cross sectional configuration of a massive p y r i t e body at Chris Creek. 96 XVII Massive hematite i n Society C l i f f s Formation at occurrence R03. 107 XV ACKNOWLEDGMENT I e s p e c i a l l y t h a n k Dr. C M . T r i g g and Mr. G.N. W o o l l e t t , b o t h o f whom c o n t r i b u t e d g r e a t l y t o t h e a u t h o r ' s e d u c a t i o n as a g e o l o g i s t . T h e i r e n c o u r a g e m e n t , b o t h i n t e l -l e c t u a l l y and f i n a n c i a l l y , i s much a p p r e c i a t e d . I a l s o t h a n k Dr. A . J . S i n c l a i r and Dr. C . I . Godwin, who p r o v i d e d s u g g e s t i o n s and c o n s t r u c t i v e c r i t i c i s m o f t h e a u t h o r ' s r e s e a r c h . S p e c i a l t h a n k s i s e x t e n d e d t o Mrs. C. Shamanski who t y p e d t h e i n i t i a l d r a f t s and f i n a l m a n u s c r i p t o f t h e t h e s i s . F i n a n c i a l a s s i s t a n c e f o r i s o t o p i c s t u d i e s was p r o -v i d e d t h r o u g h t h e o f f i c e s o f Mr. R.W. H o r n a l , D e p a r t m e n t o f I n d i a n A f f a i r s and N o r t h e r n D e v e l o p m e n t , Y e l l o w k n i f e , N.W.T., Dr. D.F. S a n g s t e r , G e o l o g i c a l S u r v e y o f Canada, O t t a w a , O n t a r i o , and by Mr. C.F. A g a r , P r e s i d e n t o f N a n i s i v i k M i n e s L t d . , C a l g a r y , A l b e r t a . P e r s o n a l and r e s e a r c h e x p e n s e s were p a r t i a l l y d e f r a y e d by t h e James C o a t e s M e m o r i a l S c h o l a r s h i p d o n a t e d by R e d s t o n e M i n e s L i m i t e d and by s c h o l a r s h i p s p r o v i d e d d u r i n g 1973-1974 and 1974-1975 by t h e N a t i o n a l R e s e a r c h C o u n c i l o f Canada. Mr. L. S i n g l e t o n gave p e r m i s s i o n f o r t h e a u t h o r t o p u b l i s h i n f o r m a t i o n on Hawker C r e e k and a d j a c e n t a r e a s a c q u i r e d on b e h a l f o f G l o b a l A r c t i c I s l a n d s L i m i t e d d u r i n g 1973. I w i s h t o ack n o w l e d g e t h e work o f Dr. H. G e l d s e t z e r whose r e c o g n i t i o n o f f a c i e s v a r i a t i o n s , h i a t a l e p i s o d e s and k a r s t phenomena w i t h i n P r o t e r o z o i c s e d i m e n t s e x i s t i n g a t n o r t h B a f f i n I s l a n d l a i d t h e ba s e f o r t h i s s t u d y . L a s t l y , I w o u l d l i k e t o t h a n k my w i f e June f o r h e r c o n t i n u e d p a t i e n c e and good humour, p a r t i c u l a r l y d u r i n g t h e t i m e s when I had n e i t h e r . 1 CHAPTER I - INTRODUCTION 1.1 LOCATION Nanisivik and Hawker Creek zinc-lead deposits are at north B a f f i n Island, D i s t r i c t of Franklin, N.W.T. within NTS 48A and 48C. The deposits are centered on 73°02 I30" N lat i t u d e , 84°28' W longitude and 72°54' N l a t i t u d e , 83°29' W longitude respectively. Resolute at; Cornwall is': Island i s ' 240 miles northwesterly (Figure 1). 1.2 TOPOGRAPHY AND CLIMATE Northern B a f f i n Island i s part of Lancaster Plateau (Bostock, 1964). The topography at Borden Peninsula i s rugged and r e l i e f commonly exceeds 2,000 feet, reaching a maximum of 4,300 feet at Elwin Inlet ice cap. Outcrop i s well exposed along c l i f f s but i s usually d r i f t or felsenmeer covered i n valleys and on plateaus. Seasons are i l l - d e f i n e d except winter. Temperatures begin to r i s e i n early June and snow cover disappears rapidly u n t i l the area i s r e l a t i v e l y snow-free by the end of June. The weather i s sunny but often cool from the middle of June u n t i l the l a t t e r part of August. During September freeze-up begins and bad weather i s common. 2 1.3 HISTORY The area between Strathcona Sound and Adams Sound was e x p l o r e d d u r i n g 1910-1911 and the presence of s i l v e r , l e a d and p y r i t e was r e p o r t e d ( B e r n i e r , 1911). North B a f f i n I s l a n d has been mapped by the G e o l o g i c a l Survey of Canada a t a s c a l e of one i n c h equals f o u r m i l e s and a s t r a t i g r a p h i c s u c c e s s i o n was e s t a b l i s h e d (Blackadar, 1956, 1958, 1963, 1965 and 1970; Lemon and Blackadar, 196 3; Lemon, 1956, T r e t t i n , 1965a, 1965b and 1969; Blackadar, Davison and T r e t t i n , 1963a, 1963b, 1963c and 1963d; Jackson, 1966 and 1969; Jackson and Davidson 1975; Jackson, Davidson and Morgan, 1975). N a n i s i v i k z i n c - l e a d d e p o s i t was staked by Texasgulf Inc. d u r i n g 1957. Texasgulf Inc. c a r r i e d out g e o l o g i c a l and g e o p h y s i c a l surveys, diamond d r i l l i n g and 1,825 f e e t of under-ground d r i f t i n g a t the e a s t end of the ore zone (Clayton, 1966). N a n i s i v i k Mines L t d . (formerly M i n e r a l Resources I n t e r n a t i o n a l Limited) a c q u i r e d c o n t r o l of N a n i s i v i k d e p o s i t d u r i n g 1972, c a r r i e d out g e o p h y s i c a l surveys and diamond d r i l l i n g , and had a p r o d u c t i o n f e a s i b i l i t y study prepared (Watts, G r i f f i s and McOuat L i m i t e d , 1973). N a n i s i v i k d e p o s i t i s to be brought i n t o p r o d u c t i o n d u r i n g 1976. King Resources Company ex p l o r e d f o r z i n c - l e a d d e p o s i t s on n o r t h B a f f i n I s l a n d d u r i n g 1969 and 1970 (Parker, 1969; T r i g g , W o o l l e t t & A s s o c i a t e s L t d . , e t a l , 1970; Olson, 1970) and d i s c o v e r e d z i n c - l e a d s u l p h i d e d e p o s i t s a t Hawker Creek and elsewhere (Figure 2). G l o b a l A r c t i c I s l a n d s L i m i t e d FIGURE I : LOCATION. 4 conducted d e t a i l e d and reconnaissance e x p l o r a t i o n on these d e p o s i t s and oth e r areas a t nor t h B a f f i n I s l a n d d u r i n g 1973 ( T r i g g , W o o l l e t t and A s s o c i a t e s L t d . , 1973). G e l d s e t z e r (1970) examined the P r o t e r o z o i c E q a l u l i k Group and Uluksan Group s t r a t i g r a p h i c s u c c e s s i o n from A d m i r a l t y I n l e t t o Tay Sound d u r i n g the summer of 1970. G e l d s e t z e r (1973a, 1973b) subsequently p u b l i s h e d h i s i n t e r p r e t a t i o n of the tectono-sedimentary development of the P r o t e r o z o i c succes-s i o n and o f the genesis o f z i n c - l e a d d e p o s i t s at nor t h B a f f i n I s l a n d . 1.4 STATEMENT OF PROBLEM S p h a l e r i t e - g a l e n a - p y r i t e d e p o s i t s e x i s t mainly w i t h i n S o c i e t y C l i f f s Formation of Uluksan Group at n o r t h B a f f i n I s l a n d . S o c i e t y C l i f f s Formation now c o n s i s t s mainly o f dolomite and i s u n d e r l a i n by A r c t i c Bay Formation and over-l a i n at Nanisivik-Hawker Creek area by V i c t o r Bay Formation. G e l d s e t z e r (1970, 1973b) proposed t h a t a h i a t a l i n t e r v a l e x i s t e d between d e p o s i t i o n o f S o c i e t y C l i f f s Formation and d e p o s i t i o n o f V i c t o r Bay Formation. G e l d s e t z e r c o n s i d e r e d t h i s h i a t a l i n t e r v a l to be the s i n g l e most important time i n t e r v a l w i t h r e s p e c t to s u l p h i d e d e p o s i t g e n e s i s . He suggested the f o l l o w i n g events o c c u r r e d d u r i n g t h i s i n t e r v a l : (1) S o c i e t y C l i f f s Formation limestone was u p l i f t e d and an e x t e n s i v e k a r s t developed at western Borden P e n i n s u l a . K a r s t development i n c l u d e d formation o f a l a r g e i n t e g r a t e d cave system 5 and cave c o l l a p s e b r e c c i a as sub-surface e f f e c t s , and c o n s i d e r a b l e topographic r e l i e f as a s u r f a c e e f f e c t . (2) Western Borden P e n i n s u l a then subsided to near or j u s t below sea l e v e l and an e v a p o r i t i c d e p o s i -t i o n a l environment was e s t a b l i s h e d . (3) Downward and l a t e r a l l y p e r c o l a t i n g b r i n e s of e v a p o r i t i c o r i g i n d o l o m i t i z e d S o c i e t y C l i f f s Formation, i n c l u d i n g the c o l l a p s e b r e c c i a and cement. B r i n e s were r i c h , o r were e n r i c h e d as they moved downward, i n a l k a l i s and c h l o r i d e and c a r r i e d base metals, o r g a n i c m a t e r i a l , sulphate and sulphate r e d u c i n g b a c t e r i a . (4) These b r i n e s e v e n t u a l l y reached the i n t e g r a t e d cave system where sulphate was reduced by sulphate r e d u c i n g b a c t e r i a and metal s u l p h i d e s were d e p o s i t e d , e v e n t u a l l y completely f i l l i n g and choking o f f the cave system. (5) Western Borden P e n i n s u l a was u p l i f t e d and evapor-i t e s p r e v i o u s l y d e p o s i t e d on S o c i e t y C l i f f s Formation were eroded p r i o r to d e p o s i t i o n of V i c t o r Bay Formation. The present study was undertaken to t e s t G e l d s e t -zer's model and to attempt to answer the f o l l o w i n g q u e s t i o n s . (1) Cave development. (a) Can massive s u l p h i d e d e p o s i t s be d e s c r i b e d as s u l p h i d e - f i l l e d paleocaves? I f yes, 6 (b) when were the caves developed and what were the pr o c e s s ( e s ) by which cave development o c c u r r e d , the source and o v e r a l l flow d i r e c -t i o n o f k a r s t waters, and the r e l a t i o n s h i p between cave development and b r e c c i a w i t h i n S o c i e t y C l i f f s Formation? (2) Sulphide emplacement. (a) When were s u l p h i d e s deposited? (b) What were the o r i g i n , composition and flow d i r e c t i o n ( s ) o f ore f l u i d s ? (c) What were the p h y s i c a l - c h e m i c a l c o n d i t i o n s which e x i s t e d d u r i n g ore d e p o s i t i o n ? (3) Post-ore m o d i f i c a t i o n s . (a) Were there any s i g n i f i c a n t post-ore m o d i f i c a -t i o n s ? During the summers o f 1970 and 197 3 the author geo-l o g i c a l l y examined the P r o t e r o z o i c s u c c e s s i o n and z i n c - l e a d d e p o s i t s at n o r t h B a f f i n I s l a n d . Short v i s i t s t o the area were a l s o made d u r i n g the summers o f 1974 and 1975. F i e l d s t u d i e s were supplemented by l a b o r a t o r y i n v e s t i g a t i o n s d u r i n g the w i n t e r s o f 1973/74 and 1974/75. 7 CHAPTER II - STRATIGRAPHIC RELATIONSHIPS AND STRUCTURE North B a f f i n I s l a n d i s u n d e r l a i n by g r a n i t i c , meta-morphic, sedimentary and v o l c a n i c rocks of Aphebian and p o s s i b l y Archean, to S i l u r i a n age (Table I; F i g u r e 3). A p p r o x i -mately 6,000 f e e t o f Mesozoic to T e r t i a r y s t r a t a are r e p o r t e d to e x i s t at B y l o t I s l a n d (Jackson and Davidson, 1975). II.1 PROTEROZOIC ROCKS Basement comprises g r a n i t i c r o c k s , g r a n i t e g n e i s s , banded g n e i s s , mafic gneiss and migmatite.. The gneiss i s h i g h l y f o l d e d and c o n t o r t e d and i s o v e r l a i n w i t h angular uncon-f o r m i t y by unmetamorphosed P r o t e r o z o i c v o l c a n i c and sedimentary rocks w i t h a t o t a l t h i c k n e s s exceeding 18,000 f e e t a t Borden P e n i n s u l a . Unmetamorphosed P r o t e r o z o i c rocks are d i v i s i b l e i n t o E q a l u l i k Group and Uluksan Group. Blackadar (1970) d i v i d e d these two rock groups i n t o e l e v e n formations. G e l d -s e t z e r (1970) found t h a t s e v e r a l formations were l a t e r a l f a c i e s e q u i v a l e n t s and d i v i d e d E q a l u l i k Group and Uluksan Group i n t o f i v e d e p o s i t i o n a l episodes (Table I ) . E q a l u l i k Group Nauyat Formation P r i o r to the d e p o s i t i o n of E q a l u l i k Group, Aphebian basement was eroded to a s u r f a c e with low r e l i e f . E q a l u l i k Group was i n i t i a t e d by e x t r u s i o n of b a s i c v o l c a n i c , columnar 8 and amygdaloidal flows and t u f f o f Nauyat Formation. Nauyat Formation i s up to 2,000 f e e t t h i c k from M o f f e t I n l e t to Elwi n I n l e t but t h i n s to the e a s t . Nauyat Formation i s g e n e r a l l y o v e r l a i n by quartz sandstone and q u a r t z i t e of Adams Sound Formation. East of Milne I n l e t Nauyat Formation i s absent and Adams Sound Formation d i r e c t l y o v e r l i e s Aphebian basement. South o f Adams Sound and a t B y l o t I s l a n d , v o l c a n i c rock and q u a r t z i t e are interbedded (Blackadar, 19 70; Jackson and David-son, 1975). I t i s p o s s i b l e t h a t Nauyat Formation v o l c a n i c rocks were extruded mainly along the major f a u l t zones which e x i s t a t Borden P e n i n s u l a , and are, i n p a r t , c o r r e l a t i v e with lower Adams Sound Formation. G e l d s e t z e r (1973b), however, suggested a h i a t a l p e r i o d separated the Nauyat Formation v o l c a n i c event from the d e p o s i t i o n o f Adams Sound Formation q u a r t z i t e as he b e l i e v e d Nauyat Formation had been eroded e a s t o f Milne I n l e t . Adams Sound Formation Adams Sound Formation g e n e r a l l y comprises l i g h t c o l o r e d , cross-bedded and r i p p l e marked, quartz sandstone or q u a r t z i t e . The t h i c k n e s s of the formation may exceed 4,000 f e e t . Adams Sound Formation grades upward i n t o b l a c k s i l t s t o n e and shale o f A r c t i c Bay Formation. Uluksan Group A r c t i c Bay Formation The lower p a r t of A r c t i c Bay Formation comprises b l a c k , g y p s i f e r o u s , o r g a n i c - r i c h s h a l e . The t r a n s i t i o n zone T A B L E I T A B L E O F F O R M A T I O N S E r a P e r i o d G r o u p ( a p p r o x i m a t e t h i c k n e s s i n f e e t ) F o r m a t i o n a p p r o x i m a t e t h i c k n e s s i n f e e t ) L i t h o l o g y ( Q u a t e r n a r y I S i l t s , g r a v e l s , c l a y s D i s c o n f o r m i t v T e r t i a r y E c l i p s e S a n d s t o n e , s i l t s t o n e , t o ( 3 , 5 0 0 t o ' m u d s t o n e , c o a l C r e t a c e o u s 6 , 0 0 0 ) D i s c o n f o r m i t y M i d d l e C a p e L i m e s t o n e , d o l o m i t e . S i l u r i a n C r a u f o r d e v a p o r i t e s o l u t i o n a n d ( ? ) ( 1 , 3 4 0 ) b r e c c i a y o u n g e r B r o d e u r L a t e ( 1 , 4 0 0 t o B a i l l a r g e D o l o m i t i c l i m e s t o n e , M i d d l e 2 , 9 4 0 ) ( 1 0 0 t o d o l o m i t e , s h a l e O r d o v i c i a n 1 , 6 0 0 ) t o M i d d l e S i l u r i a n D i s c o n f o r m i t y E a r l y a n d S h i p P o i n t D o l o m i t e ; s o l u t i o n o •H e a r l y ( 1 5 0 t o t h i n n i n g a n d b r e c c i a leozo M i d d l e O r d o v i c i a n 9 0 0 ) a t t o p leozo C o n t a c t r e l a t i o n s u n c e r t a i n ( d i s c o n f o r m a b l e t o ra cu n o r t h a n d c o n f o r m a b l e t o s o u t h ? ) E a r l y T u r n e r D o l o m i t e , m o s t l y O r d o v i c i a n C l i f f s s h a l y a n d s i l t y ; a n d / o r ( 0 t o s i l t s t o n e , s h a l e ; C a m b r i a n A d m i r a l t y ( 0 t o 2 , 1 3 3 ) 1 , 0 0 8 ) m i n o r o o l i t i c i r o n " o r e " D i s c o n f o r m i t y ? G a l l e r y R e d d i s h q u a r t z ( 0 t o s a n d s t o n e ; s o m e l ; 1 2 5 ) g r e e n i s h c l a s t i c r o c k s R e g i o n a l a n g u l a r u n c o n f o r m i t y ( L o c a l l y d i s c o n f o r m a b l e ) | G a b b r o a n d d i a b a s e I n t r u s i v e C o n t a c t E l w i n S a n d s t o n e , s i l t s t o n e , ( 5 , 0 0 0 ± ) s h a l e S t r a t h c o n a S a n d s t o n e , m u d s t o n e . S o u n d s i l t s t o n e , c o n g l o m e r -( 4 , 0 0 0 + ) , a t e ( e x i s t s w e s t o f a n d A t h o l e M i l n e I n l e t ) . S i l t -P o i n t s t o n e , l i m e s t o n e . ( 2 , 0 0 0 + ) s a n d s t o n e ( e x i s t s e a s t o f M i l n e I n l e t ) R e g i o n a l d i s c o n f o r m i t y V i c t o r B a y S h a l e , f l a t p e b b l e U l u k s a n ( 7 0 0 + t o c o n g l o m e r a t i c l i m e -o H e l i k i a n ( 1 2 , 0 0 0 ± ) 2 , 0 0 0 ) s t o n e ITOZ a n d / o r D i s c o n f o r m i t y ITOZ H a d r y n i a n S o c i e t y D o l o m i t e ; m i n o r O u C l i f f s q u a r t z s a n d s t o n e <u ( 1 , 0 0 0 + t o ( e q u i v a l e n t t o U p p e r o 2 , 0 0 0 ) F a b r i c i u s F i o r d u ft F o r m a t i o n ) a n d s o m e i n t e r b e d d e d c l a s t i c r o c k s a n d e v a p o r i t e s D i s c o n f o r m i t y A r c t i c B a y S h a l e , m i n o r d o l o m i t e ( 1 , 5 0 0 t o ( e q u i v a l e n t t o L o w e r 2 , 0 0 0 + ) F a b r i c i u s F i o r d F o r m a t i o n . a n d t o A u t r i d g e F o r m a t i o n ) A d a m s S o u n d Q u a r t z i t e ( e q u i v a l e n t E q a l u l i k ( 4 , 0 0 0 + ) t o F u r y a n d H e c l a ( 4 , 0 0 0 t o F o r m a t i o n ) 6 . 0 0 0 ) D i s c o n f o r m i t y ? N a u y a t A n d e s i t e a n d b a s a l t ( 0 t o f l o w s , t u f f 2 , 0 0 0 + ) A n g u l a r u n c o n f o r m i t y A p h e b i a n G n e i s s , m i g m a t i t e , g r a n i t i c r o c k s 10 between Adams Sound Formation and A r c t i c Bay Formation i s c y c l i c . W i t h i n a p a r t i c u l a r c y c l e the g r a i n s i z e coarsens upwards from a b l a c k , mudcracked sha l e a t the base, to a more f i s s i l e , l e s s mudcracked s h a l e , to interbedded s h a l e , s i l t s t o n e and sandstone, and f i n a l l y , a t the c y c l e top, to quartz sandstone. The sandstone i s a b r u p t l y o v e r l a i n by mudcracked sha l e of the next c y c l e . G e l d s e t z e r (1970) sug-gested t h i s c y c l i c sequence may have formed w i t h i n s t a r v e d c l a s t i c t i d a l f l a t s t h a t p e r i o d i c a l l y r e c e i v e d coarse s e d i -ment from e p i s o d i c a l l y u p l i f t e d h i g h l a n d s . The commonness of mudcracked shale c e r t a i n l y i n d i c a t e s the sediments were f r e q u e n t l y s u b a e r i a l l y exposed. Gas bubble s t r u c t u r e s , which commonly extend t o bubble impressions . o.n^beddingi.plahes , ' e x i s t i n some sandstone u n i t s and i n d i c a t e a i r was trapped d u r i n g r a p i d d e p o s i t i o n of the sand. The o r i e n t a t i o n of a few trough-crossbeds, which were measured by G e l d s e t z e r (1970), i n d i c a t e the sediment source was to the southeast. W i t h i n the upper p a r t of A r c t i c Bay Formation, dolomite and medium- to c o a r s e - g r a i n e d c l a s t i c rocks are common. However, the predominant rock type i s s t i l l a b l a c k , o r g a n i c - r i c h s h a l e (Plate I . a ) . The f a c i e s change between lower and upper A r c t i c Bay Formation occurs a b r u p t l y and begins with c o a r s e - g r a i n e d , yellow-brown sandstone. Sand-stone o f t e n grades upward i n t o b l a c k , i r r e g u l a r l y laminated a l g a l dolomite o r i n t o f l a t - p e b b l e conglomeratic dolomite. The a l g a l dolomites are commonly mudcracked and c o n t a i n abundant bitumen. Large a l g a l bioherms, up to 100 f e e t h i g h 11 PLATE I . a A r c t i c Bay F o r m a t i o n o v e r l a i n by S o c i e t y C l i f f s F o r m a t i o n n e a r t h e head o f Adams Sound. The r o c k i n t h e l o w e r l e f t i s a d i a b a s e i n t r u -s i o n . The o b j e c t on t h e r i g h t s i d e o f t h e p l a t e i s a h e l i c o p t e r door f r a m e . PLATE I.b S o c i e t y C l i f f s F o r m a t i o n a t A t h o l e P e n i n s u l a . 12 by 200 f e e t w i d e , e x i s t a t K-Mesa. The u p p e r p a r t o f A r c t i c Bay F o r m a t i o n e x i s t s e a s t o f M i l n e I n l e t and a t K-Mesa b u t i s o n l y p r e s e n t as i n f r e q u e n t e r o s i o n a l remnants a t w e s t e r n B o r d e n P e n i n s u l a . The t o t a l t h i c k n e s s o f A r c t i c Bay F o r m a t i o n r a n g e s f r o m l e s s t h a n 1,500 f e e t n e a r A r c t i c Bay t o more t h a n 2,000 f e e t e a s t o f M i l n e I n l e t . S o c i e t y C l i f f s F o r m a t i o n An a b r u p t f a c i e s change f r o m A r c t i c Bay F o r m a t i o n s h a l e t o S o c i e t y C l i f f s F o r m a t i o n d o l o m i t e e x i s t s a t B o r d e n P e n i n s u l a . Reworked A r c t i c Bay F o r m a t i o n s h a l e , a v e r y c o a r s e -g r a i n e d , r o u n d e d , d o l o m i t e c o n g l o m e r a t e , and m i c r o t o p o g r a p h y commonly mark t h e b a s e o f S o c i e t y C l i f f s F o r m a t i o n . E a s t o f M i l n e I n l e t and a t A t h o l e P e n i n s u l a t h e f a c i e s change i s l e s s p r o n o u n c e d ; s t r o m a t o l i t i c d o l o m i t e and c o a r s e - g r a i n e d c l a s t i c r o c k s c h a r a c t e r i z e b o t h u p p e r A r c t i c Bay F o r m a t i o n and l o w e r S o c i e t y C l i f f s F o r m a t i o n . The two f o r m a t i o n s a r e d i s t i n -g u i s h a b l e , however, as A r c t i c Bay F o r m a t i o n s t r o m a t o l i t i c d o l o m i t e i s y e l l o w i s h o r b r o w n i s h - g r e y , i r r e g u l a r l y l a m i n a t e d d o l o m i t e w h i c h i s i n t e r b e d d e d w i t h b l a c k s h a l e o r brown, c o a r s e - g r a i n e d s a n d s t o n e , whereas S o c i e t y C l i f f s F o r m a t i o n s t o m a t o l i t i c d o l o m i t e i s g r e y , r e g u l a r l y l a m i n a t e d d o l o m i t e w h i c h i s i n t e r b e d d e d w i t h v a r i c o l o r e d s h a l e , s i l t s t o n e and s a n d s t o n e . S o c i e t y C l i f f s F o r m a t i o n c a n be d e s c r i b e d , i n g e n e r a l , as a g r e y t o g r e y - b r o w n , p e t r o l i f e r o u s d o l o m i t e ( P l a t e I.b) w h i c h r a n g e s i n t h i c k n e s s f r o m 2,000 f e e t n e a r Tay Sound t o 13 1,000 f e e t a t St. Georges S o c i e t y C l i f f s west of the settlement of A r c t i c Bay. In d e t a i l , the v e r t i c a l and l a t e r a l s t r a t i -g r a p h i c v a r i a t i o n s w i t h i n the formation are complex. Four d i s t i n c t l i t h o f a c i e s e x i s t . These a r e : (1) r e g u l a r l y laminated a l g a l dolomite, (2) nodular, i r r e g u l a r l y laminated a l g a l dolomite, (3) d o l o l u t i t e , and (4) sandstone, s i l t s t o n e , and e v a p o r i t e . These l i t h o f a c i e s occur i n d i v i d u a l l y or i n combination. - G e l d s e t z e r (1970, 1973a) d e f i n e d t h i r t e e n f a c i e s m o d i f i c a t i o n s . The lower p a r t o f S o c i e t y C l i f f s Formation d i s p l a y s a l l p o s s i b l e f a c i e s m o d i f i c a t i o n whereas the upper p a r t o f the form a t i o n i s g e n e r a l l y r e g u l a r l y laminated a l g a l d olomite. R e g u l a r l y laminated a l g a l dolomite comprises d o l o -mite laminae w i t h a c o n s i s t e n t t h i c k n e s s o f 0.05 i n c h e s , separated by t h i n accumulations of o r g a n i c matter (Plate I I . a ) . M o d i f i c a t i o n s i n c l u d e bioherms and interbedded d o l o l u t i t e ( P l a t e I I . b ) . Bioherms are common a t e a s t e r n Borden P e n i n s u l a and e a s t o f Milne I n l e t but are l e s s common a t western Borden P e n i n s u l a . The amount o f interbedded d o l o l u t i t e i s v a r i a b l e but g e n e r a l l y ranges from 5 t o 20 volume per cen t . A l l d o l o -mite w i t h i n S o c i e t y C l i f f s Formation u s u a l l y emits a p e t r o l i -f erous odour when broken but a p e t r o l i f e r o u s odour i s par -t i c u l a r l y n o t i c e a b l e from r e g u l a r l y laminated a l g a l d o l o mite. R e g u l a r l y laminated a l g a l dolomite i s moderate grey on a f r e s h broken s u r f a c e but has a brownish c a s t on the weathered s u r -f a c e . At S t . Georges S o c i e t y C l i f f s and a t the l a r g e mesas l o c a t e d f i v e t o e i g h t m i l e s south of the head of Strathcona 14 PLATE I I . a R e g u l a r l y l a m i n a t e d a l g a l d o l o m i t e o f S o c i e t y C l i f f s F o r m a t i o n ; m o d i f i e d by c o n f o r m a b l e m o s a i c b r e c c i a . N o t e t h e s m a l l f r a c t u r e s (now cemented) p a s s i n g t h r o u g h t h e b r e c c i a t e d z o n e s . PLATE I I . b I n t e r b e d d e d r e g u l a r l y l a m i n a t e d a l g a l d o l o m i t e and d o l o l u t i t e o f S o c i e t y C l i f f s F o r m a t i o n ; m o d i f i e d by c r a c k l e b r e c c i a a n d s p a r r y d o l o m i t e v e i n i n g . 15 Sound, S o c i e t y C l i f f s Formation dolomite has a d i s t i n c t i v e reddish-orange c a s t on the weathered s u r f a c e because o f hematite s t a i n i n g . Nodular, i r r e g u l a r l y laminated a l g a l dolomite com-p r i s e s c l o s e l y spaced laminae of b l a c k carbonaceous matter which are f r e q u e n t l y d i s r u p t e d by nodules of grey, u s u a l l y f e a t u r e l e s s , vuggy dolomite. A c i c u l a r c r y s t a l molds a f t e r gypsum are r a r e w i t h i n dolomite nodule c o r e s . Nodules commonly are o u t l i n e d by a gypsum c o a t i n g . G e l d s e t z e r (1970) suggested t h i s f a c i e s i s an i n t e r t i d a l to s u p r a t i d a l d e p o s i t analogous to Recent nodular dolomite forming below sabkas of the P e r s i a n Gulf r e g i o n . S e v e r a l hundred f e e t of nodular, i r r e g u l a r l y laminated a l g a l dolomite e x i s t a t S t . Georges S o c i e t y C l i f f s . Elsewhere, t h i s f a c i e s i s l e s s common but does e x i s t near the base o f S o c i e t y C l i f f s Formation a t the head of Adams Sound and a t Magda L a k e - A l f a R i v e r area. D o l o l u t i t e has a banded appearance i n outcrop and e x i s t s i n beds which r a r e l y exceed 2 f e e t i n t h i c k n e s s . Sedimentary s t r u c t u r e s present i n c l u d e cross-bedding, slumps, c o n v o l u t i o n s and scour. D o l o l u t i t e i s commonly interbedded with r e g u l a r l y laminated a l g a l dolomite. Contacts between the two f a c i e s are sharp. D o l o l u t i t e a l s o grades i n t o nodular, i r r e g u l a r l y laminated a l g a l dolomite or i n t o f l a t - p e b b l e con-glomerate d o l o l u t i t e . Quartz sandstone, which i s l o c a l l y f e l d s p a t h i c , c h a r a c t e r i z e s the lower p a r t of S o c i e t y C l i f f s Formation immediately west and south o f Magda Lake. T h i s f a c i e s t h i n s n o r t h e r l y towards Adams R i v e r where lowermost S o c i e t y C l i f f s Formation i s d o l o l u t i t e w i t h minor quartz sandstone. E a s t of Milne I n l e t v a r i c o l o r e d s i l t s t o n e and sandstone are i n t e r -bedded wi t h gypsum i n a c y c l i c manner. A s a n d s t o n e - s i l t s t o n e -gypsum c y c l e comprises grey to green sandstone a t the base, yellow and red f i s s i l e s i l t s t o n e with interbedded gypsum i n the c e n t r a l p a r t , and green t o grey s i l t s t o n e and sandstone at the top. C l a s t i c rocks are u s u a l l y cross-bedded, r i p p l e marked and mudcracked. Gypsum and interbedded s h a l e are up to tens of f e e t t h i c k . Sandstone-siltstone-gypsum c y c l e s are i n t e r t o n g u e d w i t h r e g u l a r l y laminated a l g a l dolomite throughout most of S o c i e t y C l i f f s Formation, with the excep-t i o n o f the upper few hundred f e e t o f s t r a t i g r a p h i c s e c t i o n , but t h i n t o the west and are absent west of Milne I n l e t . R e g u l a r l y laminated a l g a l dolomite and d o l o l u t i t e are l o c a l l y reworked to f l a t - p e b b l e conglomerate. F l a t -pebble conglomerate e x i s t s w i t h i n the lower p a r t of S o c i e t y C l i f f s Formation a t c e n t r a l and western Borden P e n i n s u l a , and throughout the formation e a s t of Milne I n l e t . F l a t -pebble conglomerate i n modern environments commonly forms w i t h i n shallow s u b t i d a l to i n t e r t i d a l - s u p r a t i d a l environments d u r i n g u n u s u a l l y h i g h energy p e r i o d s caused by o c c a s i o n a l storms. Black to l i g h t grey c h e r t i s l o c a l l y p r e s e n t w i t h i n S o c i e t y C l i f f s Formation. Chert s e l e c t i v e l y r e p l a c e s a l g a l dolomite e a s t of Milne I n l e t and e x i s t s as c o n c r e t i o n a r y masses at western Borden P e n i n s u l a . 17 S o c i e t y C l i f f s Formation i s e x t e n s i v e l y b r e c c i a t e d a t western Borden P e n i n s u l a . B r e c c i a e x i s t s l o c a l l y a t e a s t e r n Borden P e n i n s u l a , most n o t a b l y a t S u r p r i s e Creek, Quiet R i v e r and K-Mesa. E a s t of Milne I n l e t b r e c c i a i s absent w i t h i n S o c i e t y C l i f f s Formation. B r e c c i a e x i s t s mainly i n r e g u l a r l y laminated a l g a l dolomite and i s r a r e or absent i n nodular, i r r e g u l a r l y laminated a l g a l d olomite, d o l o l u t i t e , f l a t - p e b b l e conglomerate o r sandstone. B r e c c i a fragments are angular to subrounded, commonly have an equant or r e c t a n g u l a r shape and g e n e r a l l y range from a f r a c t i o n of an i n c h to about 12 inches i n diameter. B r e c c i a v a r i e t i e s i n c l u d e c r a c k l e b r e c c i a , mosaic b r e c c i a and rubble b r e c c i a . In c r a c k l e b r e c c i a 1 , u n r o t a t e d dolomite fragments are cemented by white s p a r r y dolomite which commonly forms an anastomosing network of v e i n s or cemented j o i n t s ( P l a t e s II.b and I I I . a ) . In mosaic b r e c c i a , dolomite fragments are r o t a t e d but are not f a r from t h e i r o r i g i n a l p o s i t i o n . The l a r g e fragments are e i t h e r cemented by white sp a r r y dolomite or they are supported by f i n e r g r a i n e d f r a g -ments of dolomite (P l a t e s I l l . b and IV.a). In r u b b l e b r e c c i a , dolomite fragments are c h a o t i c a l l y o r i e n t e d and are not s o r t e d ( P l a t e s IV.a and IV.b). Rubble b r e c c i a m a t r i x c o n s i s t s of f i n e - g r a i n e d fragments of h o s t dolomite o r of white s p a r r y dolomite cement. Rubble b r e c c i a i s 'conformable' and 'noncon-formable'. Conformable rubble b r e c c i a i s bounded by u n b r e c c i -ated beds and e x i s t s i n l a y e r s r a n g i n g up to 3 f e e t t h i c k (Plate I I . a ) . Conformable rubble b r e c c i a g e n e r a l l y terminates 18 a b r u p t l y a g a i n s t u n d e r l y i n g u n b r e c c i a t e d dolomite but commonly grades upwards i n t o mosaic b r e c c i a , then c r a c k l e b r e c c i a and f i n a l l y i n t o u n b r e c c i a t e d dolomite (Plate I l l . b ) . Conformable rubble b r e c c i a can grade l a t e r a l l y i n t o nonconformable rubble b r e c c i a . Nonconformable rubble b r e c c i a t r a n s e c t s bedding. The t r e n d to nonconformable ru b b l e b r e c c i a zones commonly p a r a l l e l s major j o i n t d i r e c t i o n s . Such zones are u s u a l l y a few f e e t wide by s e v e r a l tens of f e e t long. Nonconformable rub b l e b r e c c i a a l s o e x i s t s i n i r r e g u l a r l y shaped zones without a d e f i n i t e t r e n d . B r e c c i a zones bear no c l o s e r e l a t i o n s h i p to f a u l t s or f o l d s even though t h e i r trends l o c a l l y p a r a l l e l major j o i n t d i r e c t i o n s . B r e c c i a zones a l s o bear no obvious r e l a t i o n s h i p to s u l p h i d e d e p o s i t s . That i s , b r e c c i a abundance does not i n c r e a s e i n the p r o x i m i t y of s u l p h i d e d e p o s i t s and b r e c c i a abundance i s s i m i l a r near both l a r g e and s m a l l s u l p h i d e d e p o s i t s . At N a n i s i v i k , b r e c c i a e x i s t s both above and below the main ore zone and dolomite b r e c c i a cemented by s u l p h i d e s i s p r a c t i c a l l y n o n e x i s t e n t . At western Borden P e n i n s u l a , the c o n t a c t between S o c i e t y C l i f f s Formation and V i c t o r Bay Formation i s sharp. S o c i e t y C l i f f s Formation a l g a l dolomite or dolomite b r e c c i a i s o v e r l a i n a b r u p t l y by V i c t o r Bay Formation s h a l e . No t r a n s i t i o n zone e x i s t s and c l a y d i d not f i l t e r down i n t o S o c i e t y C l i f f s Formation b r e c c i a . V i c t o r Bay Formation shale onlaps p a l e o t o p o g r a p h i c highs of S o c i e t y C l i f f s Formation a t Hawker Creek, at C h r i s Creek and p o s s i b l y a t N a n i s i v i k . At 19 PLATE I l l . b M o s a i c and c r a c k l e b r e c c i a g r a d i n g i n t o n o n c o n f o r m a b l e and c o n f o r m a b l e r u b b l e b r e c c i a w i t h i n S o c i e t y C l i f f s F o r m a t i o n . PLATE I V . a M o s a i c b r e c c i a and n o n c o n f o r m a b l e r u b b l e b r e c c i a w i t h i n S o c i e t y C l i f f s F o r m a t i o n . PLATE I V . b R u b b l e b r e c c i a w i t h i n S o c i e t y C l i f f s F o r m a t i o n . 21 K-Mesa, V i c t o r Bay Formation s h a l e e x i s t s i n a paleotopo-graphic d e p r e s s i o n on S o c i e t y C l i f f s Formation. V i c t o r Bay Formation o v e r l i e s S o c i e t y C l i f f s Forma-t i o n along the e n t i r e l e n g t h o f the b e l t o f P r o t e r o z o i c rocks exposed from A r c t i c Bay to Tay Sound, i . e . w i t h i n the Milne I n l e t Trough of Jackson and Davidson (1975). V i c t o r Bay Formation a l s o o v e r l i e s S o c i e t y C l i f f s Formation south of Mala River a t e a s t e r n Borden P e n i n s u l a (Blackadar, e t a l . , 1963), and a t n o r t h e r n B y l o t I s l a n d (Jackson and Davidson, 1975). East o f B a i l l a r g e Bay, 370 f e e t of grey, mudcracked d o l o l u t i t e , w i t h minor amounts of interbedded r e g u l a r l y laminated a l g a l dolomite and a few b l a c k c h e r t nodules, i s o v e r l a i n by 600 f e e t o f b l a c k s h a l e which i s interbedded w i t h minor amounts of l i m estone. Blackadar (1970) b e l i e v e d t h i s s t r a t i g r a p h i c s e c t i o n t o be e n t i r e l y V i c t o r Bay Formation but i n the author's o p i n i o n the grey dolomite i s a c t u a l l y S o c i e t y C l i f f s Formation and o n l y the shal e and limestone are V i c t o r Bay Formation. E a s t of Elwi n I n l e t the s t r a t i g r a p h i c sequence i s complex (Table I I ; P l a t e V ) . The dolomite a t Elwi n I n l e t i s up to 2,000 f e e t t h i c k , has a l i g h t r e d d i s h c a s t , i s n o n - p e t r o l i -f e r o u s , and c o n s i s t s o f a l g a l dolomite, d o l o l u t i t e , f l a t -pebble conglomerate and some dolomite b r e c c i a . Black c h e r t l o c a l l y r e p l a c e s dolomite. Interbedded black shale o r l i m e -stone u n i t s are not pres e n t . The dolomite i s o v e r l a i n by red mudstone, s i l t s t o n e and sandstone o f Strathcona Sound Formation or by P a l e o z o i c sediments, and i s u n d e r l a i n a t s e v e r a l l o c a t i o n s 22 by A r c t i c Bay Formation s h a l e which has the same a t t i t u d e as the o v e r l y i n g dolomite. TABLE I I STRATIGRAPHIC SECTION, ELWIN INLET AREA Formation D e s c r i p t i o n Strathcona Sound Formation Red mudstone to sandstone S o c i e t y C l i f f s Formation and/or V i c t o r Bay Formation Dolomite A r c t i c Bay Formation Black Shale Adams Sound Formation Quartz sandstone Nauyat Formation V o l c a n i c rocks I t i s probable t h a t the t h i c k dolomite a t E l w i n I n l e t i s S o c i e t y C l i f f s Formation. T h e r e f o r e , V i c t o r Bay Formation i s absent a t E l w i n I n l e t and Strathcona Sound Formation d i r e c t l y o v e r l i e s S o c i e t y C l i f f s Formation. T h i s i s reasonable because a t western B y l o t I s l a n d , Jackson and Davidson (1975) noted t h a t S o c i e t y C l i f f s Formation i s over-l a i n by a red bed sequence o f e l a s t i c s which resemble, lower Strathcona Sound Formation. b l a c k , well-bedded, l o c a l l y p y r i t i f e r o u s , f i s s i l e s i l t s t o n e and s h a l e . Sandstone l e n s e s , mudcracks, r i p p l e marks and dense y e l l o w carbonate beds are prese n t l o c a l l y near the base of the formation. Lower V i c t o r Bay Formation i s up to 700 f e e t V i c t o r Bay Formation The lower p a r t o f V i c t o r Bay Formation comprises 23 PLATE V S t r a t i g r a p h y a t E l w i n I n l e t a r e a ; l o o k i n g e a s t . Adams Sound F o r m a t i o n (Has) i s o v e r l a i n by A r c t i c Bay F o r m a t i o n (Hab), w h i c h i s o v e r -l a i n by d o l o m i t e t h a t i s p r o b a b l y S o c i e t y C l i f f s F o r m a t i o n ( H s c ? ) , w h i c h i s o v e r l a i n by l o w e r S t r a t h c o n a Sound F o r m a t i o n ( H s s l ) . The d i a g r a m b e l o w t h e p l a t e i l l u s t r a t e s t h e g e o l o g i c a l r e l a t i o n s h i p s p r e s e n t . 24 t h i c k a t Hawker C r e e k - N a n i s i v i k a r e a , p i n c h e s o u t t o t h e w e s t , t h i n s t o a c o n s i s t e n t 75 t o 100 f e e t t h i c k a t e a s t e r n B o r d e n P e n i n s u l a and e a s t o f M i l n e I n l e t , and d i s p l a y s r a p i d t h i c k -n e s s c h a n g e s t o t h e n o r t h . West o f A r c t i c Bay t h e b a s a l s h a l e i s m i s s i n g and t h e s e q u e n c e c o n s i s t s o f 40 f e e t o f d a r k c a l -c i l u t i t e w h i c h i s o v e r l a i n by c a l c a r e o u s c o n g l o m e r a t e and t h e n f l a t - p e b b l e c o n g l o m e r a t e w i t h i n t e r b e d d e d c a l c i l u t i t e . The u p p e r p a r t o f V i c t o r Bay F o r m a t i o n i s c h a r a c t e r -i z e d by c a l c a r e o u s f l a t - p e b b l e c o n g l o m e r a t e . Upper V i c t o r Bay F o r m a t i o n r e a c h e s a maximum t h i c k n e s s o f 2,000 f e e t a t e a s t e r n B o r d e n P e n i n s u l a and e a s t o f M i l n e I n l e t . A t t h e n o r t h w e s t e n t r a n c e t o W h i t e Bay a l a r g e a l g a l b i o h e r m e x i s t s i n u p p e r m o s t V i c t o r Bay F o r m a t i o n . T h i s a l g a l b i o h e r m c o n s i s t s o f compact a l g a l mounds ( r e g u l a r l y l a m i n a t e d a l g a l mats o f S o c i e t y C l i f f s F o r m a t i o n t y p e do n o t e x i s t w i t h i n V i c t o r Bay F o r m a t i o n ) and s o l u t i o n b r e c c i a ( G e l d s e t z e r , 1 9 7 0 ) . A t h o l e P o i n t F o r m a t i o n s a n d s t o n e o c c u r s i n t h e m a t r i x o f t h e b r e c c i a and a l s o o n l a p s t h e b i o h e r m . V i c t o r Bay F o r m a t i o n e x i s t i n g w i t h i n t h e M i l n e I n l e t T r o u g h i s o v e r l a i n w i t h a b r u p t f a c i e s change by A t h o l e P o i n t F o r m a t i o n s i l t s t o n e and s a n d s t o n e i n t h e e a s t , and by S t r a t h c o n a Sound F o r m a t i o n mudstone, s i l t s t o n e , s a n d s t o n e and c o n g l o m e r a t e i n t h e w est. S t r a t h c o n a Sound F o r m a t i o n - A t h o l e P o i n t F o r m a t i o n S t r a t h c o n a Sound F o r m a t i o n and A t h o l e P o i n t F o r m a t i o n a r e c o n t e m p o r a n e o u s w e s t e r n and e a s t e r n f a c i e s e q u i v a l e n t s . 25 Strathcona Sound Formation i s a c l a s t i c sequence ranging from mudstone t o boulder conglomerate. Strathcona Sound Formation i s d i v i s i b l e i n t o a lower member comprising dark red mudstone and shale and an upper member comprising grey sandstone and s i l t s t o n e . The mudstone and shale are r i p p l e marked, micro cross-bedded and mudcracked whereas the sandstone i s r i p p l e marked and cross-bedded. I n t e r f i n g e r i n g of the two l i t h o l o g i e s e x i s t s and i s w e l l d i s p l a y e d on the high c l i f f f aces on the south s i d e of the v a l l e y t h a t extends east from B a i l l a r g e Bay, where "a t h i c k s u c c e s s i o n o f w e s t e r l y d i p p i n g dark red mudstone and shale grades w i t h i n about a mile i n t o a predominantly grey s i l t s t o n e - s a n d s t o n e s u c c e s s i o n which, however, c o n t a i n s many t h i n bands of dark red mudstone. The l a t t e r i n tu r n d i s a p p e a r and along the south shore o n l y grey s i l t s t o n e and sandstones of the upper member are exposed, and these i n t u r n are o v e r l a i n by the succeeding E l w i n Formation." (Blackadar, 1970, p. 64). I n t r a f o r m a t i o n a l conglomerate beds are common w i t h i n Strathcona Sound Formation but are t h i c k e s t a t the b a s a l con-t a c t w i t h V i c t o r Bay Formation. The b a s a l conglomerate i s p o l y m i c t i c . The m a j o r i t y of c l a s t s are subangular to rounded dolomite o r limestone but a v a r i e t y of rock types, i n c l u d i n g g r a n i t i c and gneiss b o u l d e r s , e x i s t . C l a s t s are cemented by red mudstone or s i l t s t o n e . C l a s t s are g e n e r a l l y l e s s than one f o o t i n diameter but boulders up to s e v e r a l f e e t i n diameter e x i s t e a s t and n o r t h e a s t of the head of Strathcona Sound. Bas a l conglomerate e x i s t i n the formation n o r t h and west of 26 Hawker Creek, on both s i d e s o f the v a l l e y east o f B a i l l a r g e Bay, west o f N a n i s i v i k , and on the north shore o f Strathcona Sound west of Strathcona R i v e r (Blackadar, 1970). Nine m i l e s n o r t h o f the head of Strathcona Sound / a s l i g h t but d i s t i n c t a n g u l a r i t y e x i s t s between b a s a l sediments of V i c t o r Bay Forma-t i o n and the red bed sequence of Strathcona Sound Formation ( G e l d s e t z e r , 1973b). Wi t h i n the Milne I n l e t Trough, Strathcona Sound Formation grades e a s t e r l y i n t o A t h o l e P o i n t Formation. A t h o l e P o i n t Formation e x i s t s a t e a s t e r n Borden P e n i n s u l a and e a s t of Milne I n l e t . A t h o l e P o i n t Formation comprises a l t e r n a t i n g brownish-grey s i l t s t o n e , dense f i n e - g r a i n e d limestone and f i n e - g r a i n e d sandstone. A 25 f e e t t h i c k , b l a c k , p y r i t i f e r o u s shale e x i s t s a t the base of A t h o l e P o i n t Formation at Milne I n l e t area. T h i s s h a l e i s t o t a l l y d i f f e r e n t from the over-l y i n g sediments of A t h o l e P o i n t Formation and does not belong to the same s e d i m e n t o l o g i c a l e p i s o d e ; . i t may be a p a l u d a l o r l a c u s t r i n e d e p o s i t ( G e l d s e t z e r , 1973b). The t h i c k n e s s o f Strathcona Sound Formation exceeds 4,000 f e e t . A t h o l e P o i n t Formation i s about 2,000 f e e t t h i c k . E l w i n Formation Both Strathcona Sound Formation and A t h o l e P o i n t Formation grade i n t o o v e r l y i n g E l w i n Formation. E l w i n Forma-t i o n comprises a v a r i c o l o r e d assemblage of a l t e r n a t i n g r e d d i s h q u a r t z i t i c sandstone, s i l t y sandstone and micaceous s h a l e . The t o t a l t h i c k n e s s o f the formation exceeds 5,000 f e e t . 27 Gabbro and Diabase Dykes P r o t e r o z o i c rocks are i n t r u d e d by n o r t h w e s t e r l y and n o r t h ^ n o r t h w e s t e r l y t r e n d i n g diabase and gabbroic dykes. Northwesterly t r e n d i n g dykes are more common. C r o s s - c u t t i n g r e l a t i o n s h i p s e x i s t between the two dyke trends but t h e i r r e l a t i o n s h i p has not been c l e a r l y e s t a b l i s h e d . The dykes do not cut P a l e o z o i c s t r a t a . Dyke widths vary from a few f e e t to more than 400 f e e t and i n d i v i d u a l dykes can extend f o r s e v e r a l m i l e s or tens o f m i l e s . Dykes form topographic highs w i t h i n shale of A r c t i c Bay Formation and V i c t o r Bay Formation, and topographic lows w i t h i n S o c i e t y C l i f f s Formation. S o c i e t y C l i f f s Formation dolomite i s commonly bleached white adjacent to a dyke and grades through b l u i s h grey to the more t y p i c a l grey or brown, away from the dyke. The bleached a l t e r a t i o n zones extend o n l y a few f e e t t o a few tens of f e e t from the dyke margin. Contact-metamorphic m i n e r a l s are not m e g a s c o p i c a l l y p r e s e n t i n e i t h e r the dykes or the country r o c k s ; megascopic c o n t a c t e f f e c t s w i t h i n the dykes are l i m i t e d to c h i l l margins. P l a g i o c l a s e and pyroxene are the major dyke con-s t i t u e n t s and are accompanied by v a r y i n g amounts of amphibole, magnetite, b i o t i t e , p y r i t e , o l i v i n e and q u a r t z . C h l o r i t e , s e r i c i t e and s e r p e n t i n e are g e n e r a l l y p r e s e n t o n l y i n minor amounts. Blackadar (1970) found t h a t chemical d i f f e r e n c e s e x i s t between the v a r i o u s i n t r u s i o n s and t h a t l a r g e r dykes have a h i g h e r content of quartz and f e l d s p a r . 28 The dykes a t Borden P e n i n s u l a are p a r t i c u l a r l y abundant along the b e l t of P r o t e r o z o i c rocks which crop out from A r c t i c Bay, e a s t to Tay Sound. The n o r t h w e s t e r l y t r e n d -i n g group of dykes are the northwest e x t e n s i o n of the B a f f i n I s l a n d diabase dyke swarm (F a h r i g , 1971). T h i s swarm extends from n o r t h t o south B a f f i n I s l a n d and i s a p a r t of the F r a n k l i n igneous event ( F a h r i g , I r v i n g and Jackson, 1971 and 1973; F a h r i g and Schwartz, 1973). The n o r t h - n o r t h w e s t e r l y t r e n d i n g diabase may e i t h e r be p a r t o f F r a n k l i n diabases or are u n r e l a t e d and may be r e l a t e d to the Mackenzie igneous event. II.2 PHANEROZOIC ROGKS The P a l e o z o i c s u c c e s s i o n a t Borden P e n i n s u l a comprises 6,000 f e e t o f Cambrian, O r d o v i c i a n and S i l u r i a n s t r a t a d i v i s i b l e i n t o A d m i r a l t y Group, Ship P o i n t Formation and Brodeur Group (Table I ) . Ad m i r a l t y Group A d m i r a l t y Group comprises the mainly nonmarine G a l l e r y Formation and the o v e r l y i n g , shallow-marine Turner C l i f f s Formation ( T r e t t i n , 1969). G a l l e r y Formation averages more than 500 f e e t t h i c k a t c e n t r a l Borden P e n i n s u l a , r e a c h i n g 1,125 f e e t t h i c k s i x mi l e s n o r t h of A r c t i c Bay, but s t r a t i g r a p h i c a l l y t h i n s to the northwest, e a s t and south. At western Borden P e n i n s u l a , p a r t i c u l a r l y near A r c t i c Bay, r a p i d changes i n t h i c k n e s s occur over s h o r t d i s t a n c e s . G a l l e r y Formation comprises mainly 29 r e d d i s h q u a r t z s a n d s t o n e a t w e s t e r n and c e n t r a l B o r d e n P e n i n s u l a b u t g r e e n i s h mudstone, s i l t s t o n e and s a n d s t o n e e x i s t n e a r B a i l l a r g e Bay. P a l e o c u r r e n t measurements i n d i c a t e t h e s e d i m e n t was d e r i v e d f r o m s o u t h e r l y and n o r t h w e s t e r l y s o u r c e s ( T r e t t i n , 1 9 6 9 ) . T u r n e r C l i f f s F o r m a t i o n t h i c k n e s s r a n g e s f r o m 95 t o 1,008 f e e t . The f o r m a t i o n i s t h i c k e s t a t e a s t e r n B o r d e n P e n i n s u l a and t h i n s t o t h e n o r t h , west and s o u t h . A t n o r t h e r n and s o u t h e r n B o r d e n P e n i n s u l a , and a t B r o d e u r P e n i n s u l a , T u r n e r C l i f f s F o r m a t i o n c o m p r i s e s f i n e - t o m e d i u m - g r a i n e d c l a s t i c s e d i m e n t s d e p o s i t e d i n a n e a r s h o r e , p r o b a b l y i n t e r -t i d a l e n v i r o n m e n t . A t c e n t r a l B o r d e n P e n i n s u l a t h e f o r m a t i o n c o m p r i s e s m a i n l y s h a l l o w w a t e r d o l o m i t e w i t h i n t e r b e d d e d c l a s t i c r o c k s w h i c h were d e p o s i t e d on a c l a s t i c - s t a r v e d c a r b o n a t e s h e l f i n t o w h i c h t h e r e were p e r i o d i c p u l s e s o f s e d i m e n t ( T r e t t i n , 1 9 6 9 ) . The e x a c t age o f A d m i r a l t y Group i s u n c e r t a i n ; G a l l e r y F o r m a t i o n i s p r o b a b l y Lower t o Upper C a m b r i a n and T u r n e r C l i f f s F o r m a t i o n i s p r o b a b l y Upper C a m b r i a n t o Lower O r d o v i c i a n ( T r e t t i n , 1969; Mayr, 1 9 7 5 ) . S h i p P o i n t F o r m a t i o n The E a r l y and e a r l y M i d d l e O r d o v i c i a n S h i p P o i n t F o r m a t i o n i s p r e d o m i n a n t l y d o l o m i t i c ( T r e t t i n , 1 9 6 9 ) . I t o v e r l i e s T u r n e r C l i f f F o r m a t i o n d i s c o n f o r m a b l y a t c e n t r a l and n o r t h e r n B o r d e n P e n i n s u l a b u t may be c o n f o r m a b l e t o t h e s o u t h . S h i p P o i n t F o r m a t i o n i s o f s h a l l o w w a t e r m a r i n e o r i g i n ; t h e a n c i e n t s h o r e l i n e was t o t h e s o u t h and w e s t ( T r e t t i n , 196 9 ) . 30 The c o n t a c t between S h i p P o i n t F o r m a t i o n and B r o d e u r Group i s r a r e l y e x p o s e d . S o u t h e a s t o f E l w i n I n l e t , S h i p P o i n t F o r m a t i o n i s a n o m a l o u s l y t h i n and b r e c c i a and a s o l u t i o n zone e x i s t a t t h e t o p o f t h e f o r m a t i o n . Near t h e mouth o f M a l a R i v e r a s t e e p l y d i p p i n g b r e c c i a p i p e , w h i c h may be a s i n k h o l e formed by s o l u t i o n - c o l l a p s e , e x i s t s w i t h i n t h e l o w e r p a r t o f S h i p P o i n t F o r m a t i o n . T h e s e f e a t u r e s i n d i c a t e a r e g i o n a l h i a t u s o c c u r r e d p r i o r t o d e p o s i t i o n o f B r o d e u r Group ( T r e t t i n , 1 9 6 9 ) . B r o d e u r Group B r o d e u r Group c o m p r i s e s t h e l a t e M i d d l e O r d o v i c i a n t o p o s s i b l e M i d d l e S i l u r i a n B a i l l a r g e F o r m a t i o n and t h e c o n -f o r m a b l y o v e r l y i n g M i d d l e t o p o s s i b l e L a t e S i l u r i a n Cape C r a u f o r d F o r m a t i o n . B r o d e u r Group i s a t r a n s g r e s s i v e - r e g r e s s i v e c y c l e ; maximum submergence o c c u r r e d d u r i n g L a t e O r d o v i c i a n and E a r l y S i l u r i a n . B r o d e u r Group i s o v e r l a i n d i s c o n f o r m a b l y by M e s o z o i c t o R e c e n t s e d i m e n t s . B a i l l a r g e F o r m a t i o n c o m p r i s e s i n t e r s t r a t i f i e d d o l o -m i t e and s h a l e i n t h e l o w e r member, A, and c a r b o n a c e o u s d o l o m i t i c l i m e s t o n e i n t h e u p p e r member, B. The t h i c k n e s s o f B a i l l a r g e F o r m a t i o n r a n g e s f r o m a b o u t 1,600 f e e t a t B r o d e u r P e n i n s u l a t o l e s s t h a n 100 f e e t a t e a s t e r n B o r d e n P e n i n s u l a . T r e t t i n (1969) s u g g e s t e d t h e l o w e r member was d e p o s i t e d i n v e r y s h a l l o w w a t e r w i t h r e s t r i c t e d c i r c u l a t i o n , p o s s i b l y an e v a p o r i t i c e n v i r o n m e n t i n p a r t , whereas t h e u p p e r member was d e p o s i t e d w i t h i n a s h a l l o w , p r o t e c t e d s h e l f w i t h more open c i r c u l a t i o n . 31 B a i l l a r g e F o r m a t i o n . i s c o r r e l a t i v e , i n p a r t , w i t h C o r n w a l l i s Group of c e n t r a l E l l e s m e r e I s l a n d and Pa r r y I s l a n d s (Mayr, 1975). Thumb Mountain Formation o f C o r n w a l l i s Group i s host f o r A r v i k , E c l i p s e and oth e r l e a d - z i n c d e p o s i t s a t L i t t l e C o r n w a l l i s I s l a n d area (Kerr, 1975). Cape C r a u f o r d Formation comprises up to 1,34 0 f e e t of d o l o m i t i c limestone and c a l c a r e o u s dolomite w i t h a f e t i d odour. E v a p o r i t e s o l u t i o n b r e c c i a i s common i n the formation and i n d i v i d u a l beds of b r e c c i a range from 2 f e e t to over 100 f e e t i n t h i c k n e s s and are l a t e r a l l y e x t e n s i v e . B r e c c i a beds g e n e r a l l y occur j u s t above or w i t h i n a t h i n l y i n t e r s t r a t i f i e d l imestone, d o l o m i t i c limestone and ca l c a r e o u s dolomite assem-blage which o c c a s i o n a l l y c o n t a i n s gypsum c r y s t a l c a s t s . B r e c c i a fragments are angular and range from a f r a c t i o n of an i n c h t o about 2 f e e t i n l e n g t h ( T r e t t i n , 1969). B r e c c i a has h i g h , vuggy p o r o s i t y , f r e q u e n t l y c o n t a i n s bituminous m a t e r i a l , and commonly i s accompanied by warping, f o l d i n g , s m a l l - s c a l e doming and v e r t i c a l s o l u t i o n - c o l l a p s e s t r u c t u r e s i n the over-l y i n g beds ( T r e t t i n , 1969). Cape C r a u f o r d Formation sediments were d e p o s i t e d i n a b a r r i e r - p r o t e c t e d environment. B a r r i e r s e x i s t e d n o r t h o r no r t h e a s t o f Brodeur P e n i n s u l a and caused i r r e g u l a r i t i e s i n i n f l o w , o u t f l o w and e v a p o r a t i o n i n the lagoon ( T r e t t i n , 1969). E c l i p s e Group Cretaceous to T e r t i a r y c l a s t i c r o c k s , up to 6,000 f e e t i n t h i c k n e s s , e x i s t l o c a l l y a t B y l o t I s l a n d (Jackson and 32 D a v i d s o n , 1975). No M e s o z o i c o r T e r t i a r y s t r a t a a r e known t o e x i s t a t B o r d e n P e n i n s u l a . I I . 3 REGIONAL STRUCTURE N o r t h w e s t e r l y t r e n d i n g n o r m a l f a u l t s a r e t h e d o m i n a n t s t r u c t u r e s a t B o r d e n P e n i n s u l a and f o r m m a j o r h o r s t s and g r a b e n s . P r e s e n t o u t c r o p s o f E q a l u l i k Group and U l u k s a n Group e x i s t m a i n l y w i t h i n a g r a b e n , t h e M i l n e I n l e t T r o u g h , w h i c h e x t e n d s f r o m A d m i r a l t y I n l e t t o e a s t o f Tay Sound. T h i s g r a b e n i s bounded t o t h e s o u t h by a n o r t h w e s t e r l y t r e n d i n g h o r s t o r f a u l t e d a r c h o f A p h e b i a n m e t a m o r p h i c and p l u t o n i c r o c k s c a l l e d t h e C e n t r a l B o r d e n F a u l t Zone ( T r e t t i n , 1 9 6 5 a ) . Near t h e h e a d o f Navy B o a r d I n l e t a n o t h e r h o r s t o f A p h e b i a n r o c k s , t h e Navy B o a r d H i g h , a b u t s y o u n g e r P r o t e r o z o i c s t r a t a and i s u n c o n f o r m -a b l y o v e r l a i n by G a l l e r y F o r m a t i o n . D i a b a s e dyke t r e n d s p a r a l l e l t h e m a j o r h o r s t and g r a b e n b o u n d a r y f a u l t s . E a s t e r l y t r e n d i n g and n o r t h e r l y t r e n d i n g f a u l t s a l s o e x i s t . Movements on t h e e a s t e r l y t r e n d i n g f a u l t s i n c l u d e : o f f s e t w i t h l e f t - l a t e r a l d i s p l a c e m e n t up t o o n e - t h i r d m i l e o f n o r t h - n o r t h w e s t e r l y t r e n d i n g d y k e s e a s t o f Hawker C r e e k ; o f f -s e t w i t h r i g h t - l a t e r a l d i s p l a c e m e n t up t o 200 f e e t o f n o r t h -n o r t h w e s t e r l y t r e n d i n g d y k e s a t N a n i s i v i k a r e a ; downdrop, w i t h v e r t i c a l d i s p l a c e m e n t o f s e v e r a l h u n d r e d f e e t , o f V i c t o r Bay F o r m a t i o n i n t o f a u l t - c o n t a c t w i t h S o c i e t y C l i f f s F o r m a t i o n ; and m i n o r o f f s e t , w i t h l e s s t h a n 20 f e e t o f v e r t i c a l t h r o w , o f t h e w e s t end o f N a n i s i v i k main o r e z one. Movements on t h e n o r t h e r l y t r e n d i n g f a u l t s i n c l u d e o f f s e t o f e a s t e r l y 33 t r e n d i n g f a u l t s and o f f s e t o f t h e e a s t e r n end o f N a n i s i v i k main o r e z o n e . F a u l t d i s t r i b u t i o n and r e l a t i o n s h i p s have n o t been c l e a r l y e s t a b l i s h e d a t B o r d e n P e n i n s u l a . M i n o r f a u l t movement i s p r o b a b l y v e r y common b u t l a c k o f good s t r a t i g r a p h i c m a r k e r s w i t h i n S o c i e t y C l i f f s F o r m a t i o n , l a c k o f d e t a i l e d g e o l o g i c a l mapping i n most a r e a s , and e x t e n s i v e f e l s e n m e e r and d r i f t c o v e r make f a u l t d o c u m e n t a t i o n d i f f i c u l t ; M i d d l e P r o t e r o z o i c and y o u n g e r r o c k s a t B o r d e n P e n i n s u l a a r e n o t i n t e n s e l y f o l d e d whereas A p h e b i a n basement g n e i s s i s p o l y d e f o r m e d . W i t h i n basement g n e i s s , f o l d a x e s t r e n d w est t o n o r t h w e s t and t h e d i p o f g n e i s s i c s t r u c t u r e r a n g e s f r o m v e r t i c a l t o h o r i z o n t a l (Lemon and B l a c k a d a r , 19 73) . W i t h i n t h e y o u n g e r P r o t e r o z o i c r o c k s , n o r t h w e s t e r l y t r e n d i n g open f o l d s o f low a m p l i t u d e , w i t h l i m b s d i p p i n g l e s s t h a n 15 d e g r e e s , a r e d o m i n a n t . N o r t h e r l y t r e n d i n g open f o l d s o f low a m p l i t u d e , p l u n g i n g l e s s t h a n 10 d e g r e e s n o r t h e r l y , a l s o e x i s t w i t h i n t h e y o u n g e r P r o t e r o z o i c r o c k s . P a l e o z o i c s t r a t a a r e t y p i c a l l y f l a t - l y i n g a t B o r d e n P e n i n s u l a whereas a t B r o d e u r P e n i n s u l a t h e y f o r m a g e n t l e , a r c u a t e , n o r t h e r w e s t e r l y t o s o u t h -w e s t e r l y d i p p i n g h o m o c l i n e ( T h o r s t e i n s s o n and T o z e r , 1 9 6 0 ) . I I . 4 NANISIVIK AREA N a n i s i v i k i s w i t h i n NTS 48C/1 and i s 14 m i l e s e a s t o f A r c t i c Bay ( F i g u r e 2 ) . T o p o g r a p h y i s m o d e r a t e l y r u g g e d ; e l e v a t i o n i n c r e a s e s -f r o m s e a l e v e l a t S t r a t h c o n a Sound t o 1,700 f e e t , 4 m i l e s s o u t h . 34 Creeks d r a i n n o r t h e r l y . Outcrop exposure a t N a n i s i v i k area i s l e s s than 10 per cent. Large areas are covered by dolomite felsenmeer from S o c i e t y C l i f f s Formation o r by b l a c k s h a l e from V i c t o r Bay Formation. N a n i s i v i k area has not been g e o l o g i c a l l y mapped i n d e t a i l . On e x i s t i n g maps (Watts, G r i f f i s and McOuat, 1973) l i t t l e a t t e n t i o n was g i v e n to f r a c t u r e t r e n d s , b r e c c i a or d e t a i l e d s t r a t i g r a p h i c a n a l y s i s . However, s i z e , shape and d i s t r i b u t i o n of some s u l p h i d e bodies are reasonably w e l l known from diamond d r i l l data and underground development, and, to a l e s s e r e x t e n t , from e l e c t r o m a g n e t i c surveys. N a n i s i v i k area i s u n d e r l a i n mainly by S o c i e t y C l i f f s Formation, V i c t o r Bay Formation and A r c t i c Bay Formation (Figure 4). Adams Sound Formation quartz sandstone crops out three m i l e s s o u t h e r l y . P a l e o z o i c G a l l e r y Formation caps h i l l s southwest of N a n i s i v i k d e p o s i t . The P r o t e r o z o i c formations are cut by n o r t h - n o r t h w e s t e r l y t r e n d i n g diabase dykes. A r c t i c Bay Formation e x i s t s n o r t h and west of Kuhulu Lake but i s p o o r l y exposed. At t h i s l o c a l e the formation comprises b l a c k s h a l e w i t h no interbedded dolomite. The shale i s a b r u p t l y o v e r l a i n by dolomite o f S o c i e t y C l i f f s Formation. S o c i e t y C l i f f s Formation i s predominantly grey, r e g u l a r l y laminated a l g a l dolomite, but up to 10 per cent d o l o l u t i t e e x i s t s l o c a l l y . F r a c t u r e s and b r e c c i a are common and both conformable and nonconformable rubble b r e c c i a e x i s t . The amount of b r e c c i a does not i n c r e a s e toward or over massive s u l p h i d e b o d i e s . Diamond d r i l l l o g s show t h a t b r e c c i a occurs 35 both above and below N a n i s i v i k main ore zone (Texasgulf Ihc.v, 1962). S o c i e t y C l i f f s Formation i s up to 900 f e e t t h i c k a t N a n i s i v i k and the e a s t end of N a n i s i v i k main ore zone i s about 415 f e e t above the c o n t a c t between S o c i e t y C l i f f s Formation and A r c t i c Bay Formation (Texasgulf Inc., 1962). The lower p a r t of V i c t o r Bay Formation comprises b l a c k , f i s s i l e s i l t s t o n e and s h a l e w i t h interbedded t h i n carbonate. The s i l t s t o n e and shale are incompetent and c o l l a p s e e a s i l y when weathered whereas the carbonate i s more competent. Carbonate beds i n c r e a s e s t r a t i g r a p h i c a l l y upwards and comprise f l a t - p e b b l e conglomerate i n the upper p o r t i o n o f the formation. Most carbonate i s limestone but a d o l o m i t i c boulder conglomer-ate up to 30 f e e t t h i c k , w i t h c l a s t s ranging i n s i z e from l e s s than 1 i n c h to 2 f e e t , e x i s t s west of N a n i s i v i k i n e i t h e r uppermost V i c t o r Bay Formation or lowermost Strathcona Sound Formation. The c o n t a c t between S o c i e t y C l i f f s Formation and V i c t o r Bay Formation i s w e l l exposed west of N a n i s i v i k main ore zone. There, b r e c c i a formed i n S o c i e t y C l i f f s Formation r e g u l a r l y laminated a l g a l dolomite i s a b r u p t l y o v e r l a i n by b l a c k s h a l e o f V i c t o r Bay Formation. N a n i s i v i k area i s not complexly deformed. Bedding g e n e r a l l y trends e a s t e r l y and d i p s 5 to 10 degrees n o r t h e r l y . Dominant s t r u c t u r e s are e a s t e r l y and n o r t h e r l y t r e n d i n g f a u l t s which form h o r s t s and grabens (Figure 4). For example, the h i l l u n d e r l a i n by N a n i s i v i k main ore zone i s a h o r s t which i s bounded on the n o r t h and south by two e a s t e r l y t r e n d i n g , JO 52 000 54000 56000 58000 60000 62000 64000 66000 68000 70000 72000 74 000 76000 78000 80000 82000 84000 / a - / o 3 .8 N SR > 2 ^ T f i . ' L i L I ' k"L H I I I ^ - i - V _ - . t _ . L L L L i . -\ L L l L L ~ L " L ~ L ^ L ~ ~ C -i V L L i . L L L f c l . L f c . L -. 8 MAIN OCEAN VIEW DEPOSIT \ TW*N HAKES *•* >  f c t . _ L L t . L f . 5— , -; > _ L L i i . k _ . t . » . _ . c _ . L L L ~ t ~ ^ — / _---*___ / / v L t * _ _ _ _ _ , \ L _ . L l L L _ . L L L L L L A _ . t . t _ CM LTjfciAfS*- L l - t _ V ». t- H , ». L _ L i_ _. . v t - "L. *_<>+• P * L. i . L ^ T ^ - . C v L L T > r K>_ ** v 1 *" V 1 *• V L w k, v tJmm, L w » _ _ _ L t t u L L L - *. k «0b fc X X^4L_J__ * . V -- - L L L L 1 t - * ^ t * ^ * ttt L C C W i- I . V t t t . t . L L l f T . 1 . y ^ » - ^ / ~ ~ ^ _*• »• »- * K L •-• _- t. »,, L U 4 V t - \ L <: t L L L. , L L L t t .fc. L . 4 . I f _ Z V L t L t X *. 3 L L i Q t ^ L , L L L L - . 4 . L L * . » . L L - . L * j A ^ ^ ^ W T ^ - J l 1 >• »• *• •^V A % - • * - • • * _ i . V i - 1. fc k fc*fcr-te / V X ^ ;>-4, L ^ *- L fc * • « _ * » t l • I ^ * l I I l . H • I r-^V, W / ^ ^ J W i L - V « L L >- >- V. *. L i. L L I. L 4. t L l_- ^ I slwi^ t t^r^' c^C"" i i^'-^H^ i 7 ? ^ ^ - ^ ^ , , ^*^^*-<*'.t vL*- ^l >- ' i 1 " . 1 ^ ' 1 ^ I I^Twin Lakes \ \ . . L . L . L , L , L , l „ J - . L L. S H_ A L L l L l l . l X l , L l l l l l L i ^ T ^ S l i v i i X S ^ f c W ^ j J I l i\t- l I I L L 1 . . . C ' l l l - L l - L I-*4" I- I - I I- & U W V ^ V L l l. 1 L L l. I- L. I L L- L- C 1 L T V L I. L i T v j l L ' V l - • ^-V\^X k I L L L L L i > ^ - L L L L t «. L v \ | T - V - L L > L L I. L " j, \ t . . . L L L DW'L l - L L L L L L V ) "* \ L L>.L L t L L i V ^ ^ H v . \ L \ L L . L V L. I L L l , L V j J ' S j P l i * - X Y L * , L L 4 V L Creek - '531 ± 2 0 my. ^ 4 6 3 ^ 17 m.>h / ^ - L ^ V I li L p B.ti\v\^'iV^yB, I V i ' i V i K L KL->»of I r - " N i L > ? I O T P | V i L i i i o i i i A f t " > I ll J r ' I T L i i l I » « i I i i \ ' L \ W I \ ' L \ * 4 . I N ^  West Twin \ Hemotrte / V P ' % o i f / * i i Li, t " i "i" i" k . " « \ V - A * •- • i . V i\S! L " i ' - L . ' - r lpQ* T : l LS \ \ , \ L L k>i LiS >\1 L L i_ i L t 1_ L l » L ^ _ . L L . U I I V L V L L L i_ 1- U t L ' I L l I ' L L L L L L L L L I I ^ L L L L * . L L I V l l ' ' T P l l l l i l t W , \ ^ D ' l N ' LS V L ^ / L 1 / i "if® \ j K u h u I u Elt» 866 vyyyyA v i i i i l i t , I y l L i i L n i- . L I L I I , j. ! L a k e i I i_ L. L. L V v K -. »• ' v L L, u. i_ L | _ * - i _ i _ i L i- i- *. i. \. L t lti. _ L i_ t L L. L tiytr L L \ I L L L L *• H *- L. -C L l_ L L L L L L C L L L L _ B _ l L L L L l _ . L L V L L l i V I ' A t U L " i H I ' l l L I 1 ^ 1 t t . l _ - t - T . - t - L f t f li L Tl L . L t L t L t . ^ L L L ; \ • - 1 L , • ' V . L > 4 1 1 U L L t L t L L 4*. U I L t - * X L. L U-S"* L i i . L _ . L i . t L i _ L X \ \ , /V l- L L i i- . • , L L t L l L > L L L L L L Ig^ L L L L I . L L . L T L . L I . L X ^ \ _ V " L L L L . _ / L L . L . L . 4 . 1 _ U L L L L ^ _ . L . V L L L . I . L L L . - L i J i X L. L L. V \ V \ L ' l t k L ' L L " l ' f c ' L " " l 1 I t ' L ' L , I L L L i L V L LXBI L L _ I L L L \ - - L L L L > , \ V L L L / L J - L l L L L l - L L _ . * - L L _ L l _ L L « L i L L L l _ ' l *- ^ - X L I U - L L L \ L L U L L H - L _ . L L L L L - - L L L„ L L L L L J I ' . _ L L L L _ « J C L L V L uT.»i L l » L , i _ L - L L l _ l _ l _ L L l_ L. i L L l _ fcL L. L I L L L L L L7> . L ' t L • k ' i l L L L L L f c L l L L L L . I L ». L L f t L L L i L i L l L L L L k 52000 54000 56000 58000 60 000 '«•:::::::::::::,i\ ... /; 62LJOO 64 000 66000 68000 70 <0OC 72000 l L S A 74000 76O00 78 0OO 80000 82000 84000 L E G E N D QUATERNARY DRIFT P A L E O Z O I C f^ 1 CllWS » NAT 10)1 CAMBRIAN OR EARLIER GABBSii C » « E ; ULUKSAN GROUP *.N FORMA' Oh ,P = rs STRH-MCONA SOlW! TOR-ATIOtl _J#EB STRATHCONA SOJUC r0fi_ATIO* iMA.C i DOLOMI'E VICTOR SAT . „ FORMATiOH rc—t—c—i—i I L L L " ' L L I ' | ' f * ' - '•'•"•''ON i ' dAT fORMA'IOI m m g o EOALUL K GROUP ADAMS SOUND FORMATION NAUYAT FORMATION C S T A _ "S _ f f - ned , p: -.. i - - * f ) t""*^  t4J_T5 Atpr . i . ,T,Qi ( tor .ii. -o' f, V ' _£D0;NG > I'.i.neij, .•oriio'-Tot) SULPHIDE BOOT OUTLINE m w m ^ ( Dtfifttd , Attumtd ) K-Ar PYRITE(P) or HEMATITE OUTCROP DIABASE DYKE POTASSIUM - ARGON AGE DATED IN THIS STUDY (DATES) EM-16 CONDUCTOR FIGURE 4 : GEOLOGY, NANISIVIK. Modified after Watts, Griff is a McOuot ( 1973). 37 s t e e p l y d i p p i n g f a u l t s . The s o u t h e r l y f a u l t has downdropped V i c t o r Bay Formation a t l e a s t 400 f e e t on the south s i d e , b r i n g i n g the formation i n t o f a u l t c o n t a c t with S o c i e t y C l i f f s Formation. N a n i s i v i k main ore zone, however, c r o s s e s t h i s same f a u l t with o n l y minor v e r t i c a l displacement. A n o r t h -w e s t e r l y t r e n d i n g dyke, which probably c u t s the ore zone,"'" i s a p p a r e n t l y s l i g h t l y o f f s e t w i t h r i g h t - l a t e r a l displacement by t h i s f a u l t (Figure 4). S o c i e t y C l i f f s Formation has been t e c t o n i c a l l y b r e c c i a t e d along t h i s f a u l t . F a u l t b r e c c i a i s l e s s than two f e e t t h i c k , i s exposed f o r s e v e r a l hundred f e e t , and c o n s i s t s o f i r r e g u l a r , angular to subrounded c l a s t s cemented by black, f i n e - g r a i n e d dolomite matrix. T h i s b r e c c i a i s d i s t i n c t i v e and does not resemble the u b i q u i t o u s S o c i e t y C l i f f s Formation b r e c c i a . N o r t h e r l y t r e n d i n g f a u l t s are common and o f f s e t both e a s t e r l y t r e n d i n g f a u l t s and massive s u l p h i d e bodies. For example, the e a s t end o f N a n i s i v i k main ore zone i s o f f -s e t by n o r t h e r l y t r e n d i n g f a u l t s (the throw i s 60 f e e t and s t r i k e - s l i p movement i s approximately 100 f e e t between x A b s o l u t e proof t h a t the dyke does i n f a c t c u t N a n i s i v i k main ore zone does not e x i s t a t pres e n t . Proof w i l l be o b t a i n a b l e when the underground mining which i s c u r r e n t l y i n progress reaches the c o n t a c t between the ore zone and the dyke. However, i n d i r e c t evidence i n d i c a t e s t h a t the dyke i s post ore zone because the dyke i s approximately 20 0 f e e t i n width and i s known to extend to depth from diamond d r i l l i n g y e t the ore zone does not, a p p a r e n t l y , r a d i c a l l y change i t s c o n f i g u r a t i o n from one s i d e of the dyke to the oth e r . That i s , there i s n o t h i n g to i n d i c a t e the dyke ca u s i n g 'ponding' o f the ore f l u i d , a f e a t u r e one might expect i f the dyke was pre ore zone. 38 diamond d r i l l s e c t i o n 63,717E and 63,907E b u t g r e a t e r d i s -p l a c e m e n t may e x i s t e a s t o f s e c t i o n 63,907E) ( i b i d . ) . J o i n t s and s t r i n g e r s w i t h i n S o c i e t y C l i f f s F o r m a t i o n and V i c t o r Bay F o r m a t i o n d i p s t e e p l y a t N a n i s i v i k , and t r e n d n o r t h w e s t e r l y and e a s t e r l y , p a r a l l e l i n g m a j o r f r a c t u r e d i r e c -t i o n s . J o i n t s c u t t i n g V i c t o r Bay F o r m a t i o n a r e p r e f e r e n t i a l l y e n l a r g e d where t h e y i n t e r s e c t l i m y u n i t s . S t r i n g e r s w i t h i n S o c i e t y C l i f f s F o r m a t i o n a r e c o m p r i s e d o f d o l o m i t e whereas i n V i c t o r Bay F o r m a t i o n t h e y a r e c o m p r i s e d o f c a l c i t e . I I . 5 HAWKER CREEK AREA Hawker C r e e k i s w i t h i n NTS 48A/13 and i s 23 m i l e s s o u t h e a s t o f N a n i s i v i k z i n c - l e a d d e p o s i t ( F i g u r e 2 ) . T o p o g r a p h i c r e l i e f i s a b o u t 500 f e e t . Hawker C r e e k f l o w s i n a s t r a i g h t c h a n n e l t h a t d r o p s 400 f e e t f r o m i t s h e a d w a t e r s t o i t s o u t l e t . Hawker C r e e k and o t h e r c r e e k s w i t h i n t h e a r e a d r a i n n o r t h w e s t e r l y . O u t c r o p e x p o s u r e i s a b o u t 2 0 p e r c e n t w i t h d r i f t o r f e l s e n m e e r e x i s t i n g i n t h e r e m a i n d e r o f t h e a r e a . R e c o n n a i s s a n c e and d e t a i l e d g e o l o g i c a l mapping has been c o n d u c t e d a t Hawker C r e e k a r e a ( T r i g g , W o o l l e t t and A s s o c i a t e s L t d . , 1 9 7 3 ) . Numerous z i n c - l e a d o c c u r r e n c e s e x i s t w i t h i n t h e i m m e d i a t e a r e a o f Hawker C r e e k ; t h e s e a r e p l o t t e d on F i g u r e 5 and d e s c r i b e d i n C h a p t e r I I I . Hawker C r e e k a r e a i s u n d e r l a i n m a i n l y by S o c i e t y C l i f f s F o r m a t i o n w i t h a t h i n v e n e e r o f V i c t o r Bay F o r m a t i o n s h a l e p r e s e n t l o c a l l y . N o r t h o f B r e n d a May C r e e k , S o c i e t y 39 C l i f f s Formation i s o v e r l a i n by s e v e r a l hundred f e e t o f V i c t o r Bay Formation s h a l e , which i s o v e r l a i n i n t u r n by t h i c k carbonate conglomerate and sandstone of Strathcona Sound Formation. S o c i e t y C l i f f s Formation comprises grey and brown, r e g u l a r l y laminated a l g a l dolomite i n t e r c a l a t e d w i t h s m a l l amounts of thin-bedded d o l o l u t i t e . Dolomite commonly c o n t a i n s b l a c k , d i s c o i d c h e r t nodules and c h e r t y laminae. A l g a l b i o -herm mounds up to 4 inches i n h e i g h t are p r e s e n t l o c a l l y . F r e s h l y broken dolomite emits a p e t r o l i f e r o u s odour. F r a c -t u r e s , b r e c c i a , and vugs are commonly l i n e d w i t h c o a r s e - g r a i n e d dolomite c r y s t a l s . Conformable and nonconformable rubble b r e c c i a e x i s t s . B r e c c i a i s a s s o c i a t e d w i t h s u l p h i d e m i n e r a l occurrences only l o c a l l y and the most i n t e n s e l y b r e c c i a t e d areas are commonly not s p a t i a l l y near s u l p h i d e d e p o s i t s . For example, b r e c c i a i s u b i q u i t o u s w i t h i n S o c i e t y C l i f f s Formation near the headwaters o f Hassard Creek y e t o n l y s m a l l s u l p h i d e occurrences e x i s t i n t h i s area. Grey and b l a c k , p a l e brown weathering s h a l e and f i s s i l e s i l t s t o n e of V i c t o r Bay Formation u n d e r l i e an area s o u t h e r l y of Hawker Creek (Figure 5). The c o n t a c t between S o c i e t y C l i f f s Formation and V i c t o r Bay Formation i s p o o r l y exposed at Hawker Creek; however, 3 m i l e s to the west the c o n t a c t i s w e l l exposed i n a s m a l l creek. At t h i s l o c a l e c h e r t c o n c r e t i o n s i n S o c i e t y C l i f f s Formation are t r u n c a t e d a t the c o n t a c t and V i c t o r Bay Formation sha l e and f i s s i l e 40 s i l t s t o n e l o c a l l y o v e r l a p i r r e g u l a r i t i e s i n the upper s u r f a c e of S o c i e t y C l i f f s Formation, i n d i c a t i n g t h a t the c o n t a c t i s a d i s c o n f o r m i t y . Gabbro dykes i n t r u d e a l l P r o t e r o z o i c rocks a t Hawker Creek area. Surface e x p r e s s i o n o f dykes v a r i e s depending on the formation i n t r u d e d . Dykes are t o p o g r a p h i c a l l y high w i t h i n V i c t o r Bay Formation and t o p o g r a p h i c a l l y low w i t h i n S o c i e t y C l i f f s Formation. Accumulations of r e d d i s h brown, weathered gabbro boulders i n f l o a t a re, i n many p l a c e s , the o n l y evidence of dykes w i t h i n S o c i e t y C l i f f s Formation. Most gabbro dykes p a r a l l e l o r approximately p a r a l l e l a major j o i n t s e t which s t r i k e s 32 0 degrees. Some dykes p a r a l l e l l e s s w e l l developed j o i n t s . The average t h i c k n e s s of the dykes i s 30 f e e t . Hawker Creek area i s not complexly deformed. Bedding i s h o m o c l i n a l and di p s 5 t o 15 degrees n o r t h e a s t e r l y . North w e s t e r l y t r e n d i n g f o l d s , which g e n e r a l l y have amplitudes l e s s than 5 f e e t , e x i s t . F i s s u r e s , e l l i p t i c a l domes and e l l i p t i -c a l b a s i n s , which are s t r u c t u r a l f e a t u r e s d e f i n e d by stratum contours on bedding, e x i s t w i t h i n S o c i e t y C l i f f s Formation. A f i s s u r e comprises an open f r a c t u r e w i t h w a l l s t h a t decrease i n s e p a r a t i o n downwards and i n which bedding a t t i t u d e a b r u p t l y changes a t t i t u d e from one w a l l to the o t h e r . F i s s u r e s up t o 400 f e e t long e x i s t . Length of major axes of domes and basi n s ranges from 5 to 150 f e e t whereas l e n g t h o f minor axes i s u s u a l l y l e s s than 30 f e e t . C l o s u r e never exceeds 5 f e e t . S t r i k e of f i s s u r e s and of major axes of domes and b a s i n s ranges from 320 to 340 degrees. 41 F i s s u r e s and domes or b a s i n s can e x i s t t o g e t h e r . For example, a t 130+00E, 19+00N (Figure 5) an e l l i p t i c a l b a s i n 250 f e e t long by 120 f e e t wide i s accompanied by a n o r t h w e s t e r l y t r e n d i n g f i s s u r e 8 f e e t deep by 250 f e e t long (Plate V I ) . The predominant j o i n t s e t a t Hawker Creek s t r i k e s 320 degrees and d i p s v e r t i c a l l y . Less w e l l developed j o i n t s e t s s t r i k e about 075 degrees and about 040 degrees and d i p v e r t i c a l l y . Some j o i n t s are cemented w i t h white s p a r r y dolomite. Uncemented j o i n t s are p l a n a r whereas cemented j o i n t s are both p l a n a r and b r a n c h i n g . Uncemented j o i n t s are r a r e l y t r a c e a b l e i n t o cemented j o i n t s . Numerous ' c h a n n e l - l i k e ' f e a t u r e s e x i s t on the e r o s i o n s u r f a c e p r e s e n t l y developed on S o c i e t y C l i f f s Formation a t Hawker Creek (P l a t e s VII.a and V l l . b ) . The channels were of e x p l o r a t i o n i n t e r e s t because about one-half of a l l massive s u l p h i d e occurrences a t Hawker Creek area are i n or near channels. The channels range up t o 300 f e e t wide, are from 3 t o 75 f e e t deep, and are commonly s e v e r a l hundred to a few thousand f e e t i n l e n g t h . F l o o r s of most channels are f l a t -bottomed and c o n s i s t of f r a c t u r e d dolomite pavement or d o l o -mite r u b b l e ; V-shaped channels are uncommon. Channel g r a d i e n t s are u s u a l l y g e n t l e , although the f l a t f l o o r of a channel can l o c a l l y drop a b r u p t l y , forming a s m a l l s t e p . The e l e v a t i o n of most channel f l o o r s decreases to the northwest or n o r t h . Channels south o f Hawker Creek are g e n e r a l l y a l i g n e d p a r a l l e l or s u b p a r a l l e l to the 320 degree j o i n t s e t although 42 some channels t u r n n o r t h near t h e i r t e r m i n a t i o n i n t o Hawker Creek. North of Hawker Creek many channels t r e n d n o r t h and terminate toward Brenda May Creek. Channels a l s o e x i s t a t S u r p r i s e Creek and N a n i s i v i k area but they are not as w e l l developed as a t Hawker Creek area. I I . 6 DISCUSSION The k a r s t i f i c a t i o n o f S o c i e t y C l i f f s Formation, i n c l u d i n g the formation of b r e c c i a , domes, b a s i n s , f i s s u r e s , channels and caves, and the r e l a t i o n s h i p o f these f e a t u r e s to m i n e r a l d e p o s i t s , are d i s c u s s e d i n Chapter I I I . Uluksan Group Age Basement gneiss has been dated by the potassium-argon method at s e v e r a l l o c a t i o n s on n o r t h B a f f i n I s l a n d and gave ages r a n g i n g from 1,975 ±60 m.y. to 1,590 m.y. (Lemon and Blackadar, 1963; Blackadar, 1970; Douglas, 1970). B a s a l t from Nauyat Formation gave a potassium-argon age of 903 ±140 m.y. (Blackadar, 1970). A n o r t h w e s t e r l y t r e n d i n g diabase dyke i n t r u d i n g Uluksan Group near A r c t i c Bay gave potassium-argon ages o f 915 m.y. and 1,140 m.y. when analyzed i n 1963, (Blackadar, 1970), but gave potassium-argon ages of 439 ±80 m.y. and 437 ±60 m.y. r e s p e c t i v e l y when r e - a n a l y z e d i n 1970 ( F a h r i g , I r v i n g and Jackson, 1971). The reason f o r t h i s d i s c r e p a n c y was not known. A gabbro s i l l i n t r u d i n g A u t r i d g e Formation near Cape Appel a t Fury and Hecla S t r a i t , 43 SYMBOLS ICH + Bedding (dip, f lat- lying-, strike is approximate) ^ A B recc ia zone within Society C l i f f s Formation W A A 4 0 ^ . . . . / Trend of long 2 0 - j ' ' .-: - • / a x i s i s 3 2 0 ° A x * 0 / " " \ A ->V /30 ^ A S I N 5 0 / / 8 0 / 3 2 ^ Modified after Trigg, Woollett 8 Associates Ltd., 1973 Sca le - , " ' 0 0 - Feet A - " ' ' V A / 3 2 PLATE VI Fissure and basin structures at Hawker Creek. (These features were geol o g i c a l l y mapped at a scale of 1 inch equals 100 feet.) The diagram below the plate i l l u s t r a t e s the geological r e l a t i o n s h i p s present. 44 PLATE V I I . a ' C h a n n e l s ' (bogaz) a t Hawker C r e e k . Hawker C r e e k i s t h e s n o w - f i l l e d c r e e k d r a i n i n g t o t h e r i g h t s i d e o f t h e p l a t e . The d i s t a n c e a c r o s s t h e base o f t h e p l a t e i s a p p r o x i m a t e l y one m i l e . L o o k i n g s o u t h -e a s t e r l y t o w a r d s Adams R i v e r v a l l e y . PLATE V l l . b ' C h a n n e l s ' (bogaz) a t Hawker C r e e k . The d i s t a n c e a c r o s s t h e b a s e o f t h e p l a t e i s a p p r o x i m a t e l y f i v e h u n d r e d f e e t . 45 gave potassium-argon ages of 639 ±25 m.y. and 475 ±25 m.y. (Blackadar, 1970). The 639 ±25 m.y. age i s from a sample of fine-grained dyke rock c o l l e c t e d from the i n t r u s i v e c h i l l margin and was thought to be more r e l i a b l e . Nine northwesterly trending dykes at north-central Ba f f i n Island gave potassium-argon ages ranging from 841 ±124 to 504 ±73 m.y. (Fahrig, Irving and Jackson, 1971). At Somerset Island, a diabase s i l l e x i s t i n g within Aston Formation, which i s s t r a t i g r a p h i c a l l y equivalent to Adams Sound Formation (Douglas, 1970), gave a potassium-argon age of 702 ±25 m.y. (Dixon, 1974). A north-westerly trending dyke that cuts Society C l i f f s Formation and Nanisivik main ore zone was dated by the author and gave potassium-argon ages of 531 ±20 m.y. and 463 ±17 m.y. (Appendix I ) . The 531 ±20 m.y. date i s from a sample co l l e c t e d from the central portion of the dyke whereas the 4 63 ±17 m.y. date i s from a sample co l l e c t e d near the dyke margin. Proterozoic rocks s t r a t i g r a p h i c a l l y and l i t h o l o g i -c a l l y equivalent to Uluksan Group e x i s t within the A r c t i c archipelago. These include Kennedy Channel Formation and E l l a Bay Formation at Ellesmere Island, Hunting Formation at Somerset Island, and part or a l l of Shaler Group at V i c t o r i a and Stefansson Islands (Douglas, 1970; C h r i s t i e et al_. , 1972; Dixon, 1974). Most recent authors have assigned these rock units a Hadrynian age (e.g. R. Thorsteinsson and E. T. Tozer in Douglas, 1970, pp. 552, 553 and 588; Douglas and Price, 1972; Palmer and Hayatsu, 1975), although Young and Jefferson 46 (1975a, 1975b), and J e f f e r s o n (1976) noted t h a t lower S h a l e r Group c o u l d be e i t h e r l a t e s t H e l i k i a n o r e a r l y Hadrynian. These data i n d i c a t e the age o f Uluksan Group i s Hadrynian. A f u r t h e r refinement of Uluksan Group age i s p o s s i b l e i f p a l e o c l i m a t i c data i s c o r r e l a t e d w i t h paleomagnetic data. Thick e v a p o r i t e u n i t s w i t h i n .Society C l i f f s Formation i n d i c a t e the formation was d e p o s i t e d a t low l a t i t u d e s . The magnetic i n c l i n a t i o n s o f F r a n k l i n diabases are low, i n d i c a t i n g they were a l s o emplaced a t low l a t i t u d e s ( F a h r i g , I r v i n g and Jackson, 1971 and 1973). Thus, Uluksan Group age may be c l o s e t o the mean age of i n t r u s i o n , i . e . 675 m.y., of F r a n k l i n diabases ( F a h r i g , I r v i n g and Jackson, 1971; Robertson and F a h r i g , 1971) and i s c e r t a i n l y not younger than about 5 00 m.y. Dia s t r o p h i s m and T e c t o n i c a l l y A c t i v e Areas North B a f f i n I s l a n d was a major depocenter from Middle/Late P r o t e r o z o i c t o middle P a l e o z o i c time. Sedimentary packages decreased i n t h i c k n e s s away from t h i s s i t e o f t h i c k sediment accumulation. In t o t a l , approximately 24,000 f e e t of sedimentary and v o l c a n i c rocks were d e p o s i t e d w i t h i n the g r a b e n - l i k e trough t h a t extended from Tay Sound area to Ad m i r a l t y I n l e t . The-. P r o t e r o z o i c sedimentary package was t h i c k e s t a t w e s t - c e n t r a l Borden P e n i n s u l a and i t s t h i c k n e s s decreased t o the n o r t h , south and e a s t , r e f l e c t i n g the shallow water paleoenvironments which e x i s t e d e a s t of Milne I n l e t , south o f Adams Sound towards C e n t r a l Borden F a u l t Zone, n o r t h to n o r thern Borden P e n i n s u l a , and, to a l e s s e r e x t e n t , west towards Uluksan P e n i n s u l a and A d m i r a l t y I n l e t . The f a c i e s 47 d i s t r i b u t i o n w i t h i n Uluksan Group a l s o supports the hypo-t h e s i s t h a t the b a s i n shallowed i n a l l d i r e c t i o n s d u r i n g Hadrynian time. T h i s phenomenon was repeated d u r i n g d e p o s i -t i o n of P a l e o z o i c sediments because the t h i c k n e s s o f A d m i r a l t y Group decreases away from w e s t - c e n t r a l Borden P e n i n s u l a and f a c i e s d i s t r i b u t i o n s w i t h i n the P a l e o z o i c formations suggests water shallowed away from c e n t r a l Borden P e n i n s u l a ( T r e t t i n , 1969) . Borden P e n i n s u l a area was t e c t o n i c a l l y u n s t a b l e . T h i s i s i n d i c a t e d by the abrupt f a c i e s changes and by the v a r i a t i o n s i n f a c i e s t h i c k n e s s which occur i n both P r o t e r o z o i c and P a l e o z o i c s t r a t a . The numerous d i s c o n f o r m i t i e s and/or u n c o n f o r m i t i e s t h a t e x i s t w i t h i n the s t r a t i g r a p h i c sequence show t h a t ' d e p o s i t i o n a l ' areas commonly underwent u p l i f t , non-d e p o s i t i o n and f r e q u e n t l y e r o s i o n , f o l l o w e d by subsidence and renewed d e p o s i t i o n . These f e a t u r e s show t h a t f a u l t a c t i v i t y a t n o r t h B a f f i n I s l a n d was c o n t i n u a l d u r i n g l a t e P r o t e r o z o i c to e a r l y P a l e o z o i c time. The o r i g i n of the long l i v e d trough a t n o r t h B a f f i n I s l a n d i s s p e c u l a t i v e . I t i s probably r e l a t e d to development of the F r a n k l i n i a n Geosyncline which formed d u r i n g l a t e P r o t e r o z o i c to Devonian time (Douglas, 1970). The trough i s best d e s c r i b e d as an aulacogen, here termed Borden Aulaco-gen. Aulacogens were f i r s t r e c o g n i z e d by N. S h a t s k i as t e c t o n i c f e a t u r e s i n the Russian P l a t f o r m (Salop and S c h e i n -mann, 1969). Hoffman (Hoffman, e t a l . , 1971, 1974; Hoffman, 48 1972a, 1972b, 1973a and 1973b) documented a 2, 2 00. m i l l i o n . : year o l d Canadian example and summarized aulacogen c h a r a c t e r i s t i c s (Table I I I ) . Borden Aulacogen has most of the c h a r a c t e r i s t i c s Hoffman gave as t y p i c a l o f aulacogens. Hoffman (1973b), and Burke and Dewey (1973) suggested aulacogens are i n i t i a t e d over mantle plume, t r i p l e r i f t ( i . e . r r r ) j u n c t i o n s . Aulacogens a p p a r e n t l y mark the l o c a t i o n of a f a i l e d arm or i n c i p i e n t r i f t where spr e a d i n g d i d not continue to form an ocean b a s i n . Burke and Dewey (1973) suggested t h a t a t r i p l e j u n c t i o n , the Devon I s l a n d j u n c t i o n , e x i s t e d immedi-a t e l y n o r t h o f B a f f i n I s l a n d d u r i n g Late C r e t a c e o u s / E a r l y T e r t i a r y time and t h a t L a n c a s t e r Sound, the t h i r d arm of the Devon I s l a n d j u n c t i o n , i s an a n c i e n t s t r u c t u r a l f e a t u r e t h a t was a c t i v e d u r i n g the Precambrian. D o l o m i t i z a t i o n o f S o c i e t y C l i f f s Formation Most r e c e n t authors b e l i e v e t h a t the m a j o r i t y of dolomite i s an a l t e r a t i o n product of CaCO^ (e.g. B l a t t , e t a l . , 1972; B a t h u r s t , 1975). T h e r e f o r e , the o r i g i n a l carbonate m i n e r a l s comprising S o c i e t y C l i f f s Formation were probably a r a g o n i t e and/or h i g h magnesium c a l c i t e because these are the predominant m i n e r a l s of modern a l g a l carbonate ( B l a t t , e t a l . , 1972; Friedman, e t a l . , 1973). S e v e r a l hypotheses have been proposed f o r the d o l o -m i t i z a t i o n o f CaCO^ i n c l u d i n g : (1) c a l c i f i c a t i o n of sodium smectite t o m o n t m o r i l l o n i t e which r a i s e s the Mg/Ca r a t i o o f l o c a l water and causes d o l o m i t i z a t i o n ( B l a t t , e t a l . , 1972), (2) slow d o l o m i t i z a t i o n by metasomatism w i t h normal sea water, 49 TABLE I I I AULACOGEN CHARACTERISTICS (1) Aulacogens are l o n g - l i v e d , d e e p l y - s u b s i d i n g troughs t h a t extend t r a n s v e r s e l y from o r t h o - g e o s y n c l i n e s f a r i n t o a djacent f o r e l a n d p l a t f o r m s . They are normally l o c a t e d where the g e o s y n c l i n e makes a r e - e n t r a n t angle at the margin o f the p l a t f o r m and they g r a d u a l l y d i e out toward the i n t e r i o r of the p l a t f o r m . (2) Most aulacogens begin as a narrow fault-bounded graben which extends a t an angle from the p l a t f o r m margin. The graben l a t e r becomes a broad downwarp which i s u l t i m a t e l y broken by f a u l t s i n t o h o r s t s and grabens. (3) Aulacogens p r o f o u n d l y i n f l u e n c e s edimentation. T h e i r f i l l i s contemporaneous w i t h , as t h i c k as, and l i t h -o l o g i c a l l y s i m i l a r to the f o r e l a n d sedimentary wedge of the g e o s y n c l i n e , but the i n c r e a s e i n sedimentary t h i c k n e s s from p l a t f o r m t o aulacogen i s much more abrupt than from p l a t f o r m to m i o g e o c l i n e . Sediment t r a n s p o r t of o r t h o q u a r t z i t e and molasse occurs l o n g i -t u d i n a l l y down the l e n g t h of the aulacogen. Some aulacogens are c h a r a c t e r i z e d by e v a p o r i t e s or by i n t e r m i t t e n t b a s a l t i c and r h y o l i t i c v o l c a n i s m absent from o t h e r p a r t s o f the f o r e l a n d . Fanglomerate may a l s o be p r e s e n t . (4) T e c t o n i c movement w i t h i n aulacogens i s mainly v e r t i c a l . Large s c a l e h o r i z o n t a l t r a n s l a t i o n s are r a r e although m i l d compressional deformation may occur. Low-angle o v e r t h r u s t s are absent but r e v e r s e f a u l t s can e x i s t . (5) Aulacogen sedimentary f i l l i s unmetamorphosed o r , a t most, weakly metamorphosed. B a t h o l i t h i c i n t r u s i o n s are absent, although d i a b a s i c dykes and/or s i l l s may be p r e s e n t . A f t e r Hoffman (1973a, 1973b). 50 p a r t i c u l a r l y i f temperature i n c r e a s e s d u r i n g b u r i a l ( B l a t t , e t a l . , 1972), (3) d o l o m i t i z a t i o n by hydrothermal s o l u t i o n s (Lovering, 1969), (4) d o l o m i t i z a t i o n by c a p i l l a r y e v a p o r a t i v e pumping i n , f o r example, a sabka environment (Shinn, et_ a l . , 1965; Kinsman, 1969; Friedman, e t a l . , 1973), (5) d o l o m i t i z a -t i o n by s o l u t i o n - c a n n i b a l i z a t i o n of more unstable carbonates d u r i n g u p l i f t (Goodell and Garman, 1969), (6) d o l o m i t i z a t i o n by ground water d u r i n g mixing w i t h s a l i n e b r i n e s (Hanshaw, et a l . , 1971; F o l k and Land, 1975; Land, e t a l . , 1975), and (7) d o l o m i t i z a t i o n by e v a p o r a t i v e r e f l u x (Adams and Rhodes, 1960; Deffeyes, et_ a l . , 1965). I t seems u n l i k e l y t h a t magnesium-rich c l a y s , deep b u r i a l or hydrothermal s o l u t i o n s were important d o l o m i t i z a t i o n processes a t Borden P e n i n s u l a because V i c t o r Bay Formation, an a r g i l l a c e o u s limestone d i r e c t l y o v e r l y i n g S o c i e t y C l i f f s Formation, i s not d o l o -m i t i z e d . The o t h e r p rocesses are not as e a s i l y d i s c o u n t e d and each may have been important l o c a l l y . I t seems d o u b t f u l , however, t h a t d o l o m i t i z a t i o n . by a process o f mixing meteoric water and s a l i n e b r i n e s c o u l d form dolomite u b i q u i t o u s l y over a l e n g t h of a t l e a s t 170 m i l e s . The common e x i s t e n c e of e v a p o r i t e and e v a p o r a t i c t e x t u r e s w i t h i n S o c i e t y C l i f f s Formation i n d i c a t e t h a t an e v a p o r a t i v e r e f l u x or s i m i l a r process may have been the most important d o l o m i t i z i n g p r o-cess. L u c i a (1972) noted t h a t r e f l u x d o l o m i t i z a t i o n i s an i n h e r e n t p a r t of t i d a l - f l a t s edimentation, p a r t i c u l a r l y i n a r i d and s e m i - a r i d c l i m a t e s . 51 D u r i n g d o l o m i t i z a t i o n t h e o r i g i n a l l i m e s t o n e was c o m p l e t e l y r e p l a c e d b u t i n t e n s e r e c r y s t a l l i z a t i o n d i d n o t o c c u r b e c a u s e t h e r e l i c t l i m e s t o n e t e x t u r e s a r e w e l l p r e -s e r v e d . F u r t h e r m o r e , d o l o m i t i z a t i o n d i d n o t e f f e c t an i n c r e a s e i n t h e p o r o s i t y o r p e r m e a b i l i t y o f S o c i e t y C l i f f s F o r m a t i o n . T h i s i s t o be e x p e c t e d i f d o l o m i t i z a t i o n was by e v a p o r a t i v e r e f l u x b e c a u s e t h e d o l o m i t e f o r m e d by t h i s p r o c e s s g e n e r a l l y has low p o r o s i t y ( L e i g h t o n and P e n d e x t e r , 1 9 6 2 ) . I n f a c t , t h e p o r o s i t y o f d o l o m i t e f o r m e d by t h e p r o g r e s s i v e d o l o m i t i z a t i o n o f l i m e s t o n e i s commonly e v e n l e s s t h a n t h e p o r o s i t y o f t h e o r i g i n a l l i m e s t o n e ( H e w i t t and V o g e l , 1 9 7 5 ) . Powers (19 6 2 ) , f o r example, i n a s t u d y o f J u r a s s i c c a r b o n a t e r o c k s a t n o r t h e a s t e r n S a u d i A r a b i a , f o u n d t h a t where l i m e -s t o n e had b e e n g r e a t e r t h a n 90 p e r c e n t d o l o m i t i z e d , p o r o s i t y had b e e n r e d u c e d f r o m 25 p e r c e n t t o l e s s t h a n 3 p e r c e n t and p e r m e a b i l i t y had been r e d u c e d from.1,000 m i l l i d a r c y s t o l e s s t h a n 2 m i l l i d a r c y s . T h i s phenomena, i . e . t h e f o r m a t i o n o f d o l o m i t e w i t h v e r y low p e r m e a b i l i t y en masse, i s e x t r e m e l y i m p o r t a n t t o t h e d e v e l o p m e n t o f h o l o k a r s t ( A p p e n d i x I I ) . 52 CHAPTER I I I - MINERAL DEPOSITS M i n e r a l d e p o s i t s a t Borden P e n i n s u l a have been d i s c o v e r e d by reconnaissance or d e t a i l p r o s p e c t i n g , or by follow-up p r o s p e c t i n g o f reconnaissance geochemical stream sediment survey anomalous v a l u e s . E x p l o r a t i o n has been r e s t r i c t e d mainly to the b e l t o f S o c i e t y C l i f f s Formation which extends from Uluksan P e n i n s u l a t o Tay Sound. S o c i e t y C l i f f s Formation a t n o r t h e r n m o s t Borden P e n i n s u l a and a t B y l o t I s l a n d has not been e x p l o r e d . Other formations a t Borden P e n i n s u l a have not been e x p l o r e d adequately. Four types o f m e t a l l i c m i n e r a l d e p o s i t s o r mi n e r a l occurrences e x i s t w i t h i n Late P r o t e r o z o i c rocks a t Borden P e n i n s u l a . These i n c l u d e : (1) z i n c , l e a d and/or i r o n s u l p h i d e d e p o s i t s , which e x i s t mainly w i t h i n S o c i e t y C l i f f s Formation and, t o a much l e s s e r e x t e n t , i n V i c t o r Bay Formation, (2) i r o n oxide and i r o n hydroxide d e p o s i t s i n S o c i e t y C l i f f s Formation, (3) copper s u l p h i d e occurrences i n E q a l u l i k Group and Uluksan Group sedimentary and v o l c a n i c r o c k s , and (4) i r o n s u l p h i d e , copper s u l p h i d e and i r o n oxide occurrences i n or a s s o c i a t e d with diabase i n t r u s i o n s . Z i n c , l e a d and/or i r o n s u l p h i d e d e p o s i t s are d i v i s i -b l e i n t o three sub-types: (1) 'massive z i n c - l e a d ' d e p o s i t s , (2) ' f i s s u r e - f i l l ' o c c u r r e n c e s , and (3) disseminated s u l p h i d e o c c u r r e n c e s . Z i n c , l e a d and i r o n s u l p h i d e m i n e r a l s a l s o e x i s t 53 as fragments i n felsenmeer o r i n f r o s t b o i l s . Such fragments are r e s i d u a l and are d e r i v e d from weathering o f i n s i t u m i n e r a l d e p o s i t s . In some weathered d e p o s i t s of massive p y r i t e , s p a r r y dolomite has been completely leached, l e a v i n g a l o o s e aggregate comprised e n t i r e l y . o f u n t a r n i s h e d g r a i n s o f p y r i t e . T h i s aggregate has been a p t l y termed ' p y r i t e s a n d 1 . Gossans o f g e o t h i t e and l i m o n i t e e x i s t near some su l p h i d e d e p o s i t s . Massive hematite d e p o s i t s e x i s t w i t h i n S o c i e t y C l i f f s Formation a t western Borden P e n i n s u l a and are a l s o s p a t i a l l y a s s o c i a t e d w i t h s u l p h i d e d e p o s i t s . Copper s u l p h i d e o c c u r r e n c e s , comprising c h a l c o c i t e or b o r n i t e , w i t h or without p y r i t e , m alachite and a z u r i t e , e x i s t w i t h i n P r o t e r o z o i c rocks a t s e v e r a l l o c a t i o n s a t Borden P e n i n s u l a but no copper occurrences are known to e x i s t e a s t of M i lne I n l e t . In g e n e r a l , copper occurrences are n e i t h e r common nor important w i t h i n S o c i e t y C l i f f s Formation. At S u r p r i s e Creek, however, copper m i n e r a l s are l o c a l l y abundant i n f l o a t and as f i s s u r e - f i l l i n S o c i e t y C l i f f s Formation dolomite, o r as copper s t a i n on Adams Sound Formation q u a r t z i t e . At K-Mesa, c h a l c o c i t e and b o r n i t e e x i s t as d i s s e m i n a t i o n s o r as f i s s u r e - f i l l i n upper A r c t i c Bay Formation dolomite o r i n lower S o c i e t y C l i f f s Formation dolomite. Along the n o r t h s i d e of Adams Sound two zones of stratabound m a l a c h i t e s t a i n e x i s t i n Adams Sound Formation q u a r t z i t e . South o f Adams Sound c h a l c o c i t e e x i s t s as d i s s e m i n a t i o n s and masses up to one f o o t i n diameter i n Nauyat Formation (R. B. Cooper, p e r s o n a l com-munication, 1975). Elsewhere,copper occurrences are minor. 54 P y r i t e , p y r r h o t i t e , c h a l c o p y r i t e , hematite or magnetite e x i s t l o c a l l y as d i s s e m i n a t i o n s i n dia b a s e . Magne-t i t e has l o c a l l y r e p l a c e d dolomite near the dyke-wall rock c o n t a c t s . None of the s u l p h i d e occurrences a s s o c i a t e d c l o s e l y with diabase are important. I I I . l MASSIVE ZINC-LEAD DEPOSITS Important s u l p h i d e d e p o s i t s e x i s t a t N a n i s i v i k , Hawker Creek and C h r i s Creek areas (Figure 2). The d e p o s i t s are massive, t h a t i s , s u l p h i d e s o f z i n c , l e a d and i r o n , w i t h or without s p a r r y dolomite, comprise almost 100 per cent o f a d e p o s i t . Furthermore, i n massive z i n c - l e a d deposits, s u l p h i d e s e x i s t i n g as d i s s e m i n a t i o n s o r as f i s s u r e - f i l l i n host dolomite are q u a n t i t a t i v e l y unimportant and s u l p h i d e s - e x i s t i n g as cement or m a t r i x - f i l l w i t h i n host dolomite b r e c c i a are p r a c t i c a l l y n o n - e x i s t e n t . The most eco n o m i c a l l y important massive z i n c - l e a d d e p o s i t s a t Borden P e n i n s u l a e x i s t a t N a n i s i v i k . \ ~ N a n i s i v i k main ore zone c o n t a i n s a t l e a s t 6,971,000 tons of proven and probable ore with an average grade of 14.12 per cent z i n c , 1.40 per cent l e a d and 1.77 ounces per ton s i l v e r (Watts, G r i f f i s and McOuat L i m i t e d , 1973). Small, l a r g e l y undefined, s u l p h i d e d e p o s i t s , with grades to 15.38 per cent z i n c , 1.58 per cent l e a d and 0.17 ounces per ton s i l v e r , e x i s t w i t h i n S o c i e t y C l i f f s Formation a t Hawker Creek area. Small massive p y r i t e d e p o s i t s e x i s t w i t h i n S o c i e t y C l i f f s Formation a t C h r i s Creek a r e a and a small p y r i t e d e p o s i t , which c o n t a i n s some s p h a l e r i t e , 55 e x i s t s w i t h i n V i c t o r Bay Formation at White Bay area. The s u l p h i d e d e p o s i t s a t Hawker Creek and C h r i s Creek are i n p r e l i m i n a r y stages o f e x p l o r a t i o n and t h e i r s i z e and economic p o t e n t i a l has not been e v a l u a t e d . The s u l p h i d e d e p o s i t a t White Bay has not been e v a l u a t e d . The shape of N a n i s i v i k main ore zone i s d e f i n e d by g r i d diamond d r i l l i n g and by underground development. The tr e n d o f s u l p h i d e d e p o s i t s i s i n t e r p r e t e d from the geograhic d i s t r i b u t i o n o f s u l p h i d e outcrops and/or from g e o p h y s i c a l surveys. Mineralogy, t e x t u r a l r e l a t i o n s h i p s and the c o n t a c t r e l a t i o n s h i p s between s u l p h i d e d e p o s i t s and the host dolomite are w e l l exposed i n trenches excavated a t Hawker Creek area, i n underground workings a t N a n i s i v i k d e p o s i t , and i n a creek, Twin Lakes Creek, at the west end of N a n i s i v i k main ore zone. Mineralogy and F a b r i c The mineralogy o f the massive s u l p h i d e d e p o s i t s i s r e l a t i v e l y simple and comprises mainly p y r i t e , p y r i t e pseudo-morphous a f t e r m a r c a s i t e , r e l i c t m a r c a s i t e , s p h a l e r i t e , galena and s p a r r y dolomite. M i c r o s c o p i c fabric"'" i s uncomplicated but mesoscopic f a b r i c i s more d i v e r s e . S u l p h i d e - s p a r r y dolomite i n t e r b a n d i n g i s the s t r i k i n g mesoscopic s t r u c t u r e w i t h i n the d e p o s i t s . The d e f i n i t i o n s f o r m i c r o s c o p i c , mesocopic and megascopic f a b r i c s g i v e n i n Turner and Weiss (1963) are f o l l o w e d here. 56 Sulphide M i n e r a l s P y r i t e , r e c o g n i z e d by c r y s t a l form and i s o t r o p i c t o weakly a n i s o t r o p i c c h a r a c t e r under c r o s s e d n i c o l s , e x i s t s as very f i n e - t o medium-grained, subhedral to euhedral c r y s t a l s . P y r i t e c r y s t a l h a b i t i s v a r i a b l e . b u t c r y s t a l h a b i t w i t h i n a p a r t i c u l a r d e p o s i t i o n a l environment i s c o n s i s t e n t . For example, p y r i t e e x i s t s as cubes {001}, l o c a l l y m o d i f i e d by s m a l l o c t a -h e d r a l f a c e s {111}, where i t has r e p l a c e d S o c i e t y C l i f f s Formation dolomite a t the c o n t a c t between the s u l p h i d e d e p o s i t and the host rock, whereas within, banded s u l p h i d e or i n vugs p y r i t e e x i s t s as cubes or as rounded cubes formed by o s c i l l a t o r y growth o f c u b i c and p y r i t o h e d r a l {210} f a c e s , m o d i f i e d by s m a l l {111} faces o r , r a r e l y , by s m a l l t r a p e z o h e d r a l {112} f a c e s . Zoned p y r i t e c r y s t a l s , with the zones d e f i n e d by v a r y i n g abundances o f s p a r r y dolomite i n c l u s i o n s , e x i s t l o c a l l y i n the d e p o s i t s but have no c o n s i s t e n t d i s t r i b u t i o n . Unusual 'etch' s t r u c t u r e s e x i s t on some fac e s o f euhedral c u b i c c r y s t a l s of p y r i t e which coa t the w a l l s of open c r o s s c u t t i n g f i s s u r e s t h a t e x i s t i n Twin Lakes Creek p y r i t e zone. These 'etch' s t r u c t u r e s are g e n e r a l l y c i r c u l a r and are up to 0.25 inches i n diameter by up to 0.05 inches deep. The s t r u c t u r e s l o c a l l y o v e r l a p one another, or a s m a l l one can e x i s t completely w i t h i n a l a r g e r one, and they l o c a l l y have t h e i r c i r c u l a r c o n f i g u r a t i o n terminate a b r u p t l y a t the margin of a c r y s t a l f a ce without c o n t i n u i n g onto the adjacent f a c e of the c r y s t a l . However, they can l o c a l l y extend from one c r y s t a l face to another c r y s t a l face ( i . e . on a d i f f e r e n t c r y s t a l ) a c r o s s a 57 r e e n t r a n t without an i n t e r r u p t i o n of the c i r c u l a r c o n f i g u r a -t i o n . Although these s t r u c t u r e s have been c a l l e d 'etch' s t r u c t u r e s they do not r e a l l y appear to be etched because the w a l l and f l o o r o f the s t r u c t u r e s are as shiny and uncorroded i n appearance as the surrounding p y r i t e c r y s t a l f a c e . The exact o r i g i n of the s t r u c t u r e s i s unknown. M a r c a s i t e was once a common primary m i n e r a l w i t h i n s u l p h i d e d e p o s i t s but i s now almost completely converted t o p y r i t e pseudomorphs. R e l i c t m a r c a s i t e i s present l o c a l l y and i s r e c o g n i z e d m i c r o s c o p i c a l l y by i t s s t r o n g a n i s o t r o p i s m . P y r i t e pseudomorphs o f ma r c a s i t e are f i n e - to medium-grained and are commonly subhedral to euhedral lath-shaped c r y s t a l s w i t h curved, diamond-shaped c r o s s - s e c t i o n s . C r y s t a l h a b i t s of pseudomorphs i n c l u d e : (1) o s c i l l a t o r y growth prisms p a r a l l e l t o *c', i . e . {120}, {110} and {010}, t r u n c a t e d by o s c i l l a t o r y growth on {101} and {001},, (2) p r i s m a t i c c r y s t a l s , i . e. {110}, t r u n c a t e d by {001}, and (3) t a b u l a r p r i s m a t i c c r y s t a l s on 'b 1, i . e . {010}, m o d i f i e d by {100}, {140} and {001}. Twinning on {101} has formed cockscomb and spear shapes. P y r i t e and r e l i c t m arcasite are the predominant s u l p h i d e m i n erals w i t h i n s u l p h i d e d e p o s i t s and e x i s t u b i q u i -t o u s l y throughout the d e p o s i t s . V o l u m e t r i c a l l y , p y r i t e and r e l i c t m a r c a s i t e comprise from 60 t o over 80 per cent of the t o t a l s u l p h i d e p r e s e n t . P y r r h o t i t e i s extremely r a r e . C a b r i (1973) s t a t e d t h a t hexagonal p y r r h o t i t e ( s p e c i f i c a l l y Fe QS,_) e x i s t s as 1 to 58 5 0 micron i n c l u s i o n s i n some p y r i t e a t N a n i s i v i k main ore zone. P y r r h o t i t e , r e c o g n i z e d m i c r o s c o p i c a l l y by i t s creamy brown c o l o u r i n r e f l e c t e d l i g h t and by i t s s t r o n g a n i s o t r o p i s m , e x i s t s l o c a l l y as very s m a l l , i r r e g u l a r l y - s h a p e d areas w i t h i n p y r i t e a t Hawker Creek area. A l l p y r r h o t i t e w i t h i n a p y r i t e c r y s t a l e x t i n g u i s h e s s i m u l t a n e o u s l y under c r o s s n i c o l s , i n d i c a t i n g p y r r h o t i t e i s r e p l a c e d by and/or has i n v e r t e d to p y r i t e . P y r r h o t i t e never e x i s t s i n c o n t a c t w i t h s p h a l e r i t e or o t h e r s u l p h i d e m i n e r a l s . S p h a l e r i t e i s the main ore m i n e r a l . S p h a l e r i t e abundance ranges from l e s s than 1 volume per cent to 60 volume per cent of the t o t a l ore m i n e r a l and gangue content, and averages about 25 volume per cent w i t h i n the s u l p h i d e d e p o s i t s of ore grade. S p h a l e r i t e e x i s t s as i r r e g u l a r masses i n t e r -grown wit h other m i n e r a l s or forms f i n e - t o c o a r s e - g r a i n e d , subhedral to euhedral c r y s t a l s which l o c a l l y have t r i s t e t r a -h e d r a l {211} h a b i t . Larger s p h a l e r i t e c r y s t a l s are commonly l a m e l l a r growth twinned. S p h a l e r i t e w i t h i n s u l p h i d e d e p o s i t s i s u s u a l l y dark r e d d i s h brown"'", although s m a l l , l i g h t brown s p h a l e r i t e c r y s t a l s e x i s t l o c a l l y i n vugs w i t h c a l c i t e , p y r i t e , r e l i c t m a r c a s i t e , s p a r r y dolomite, o r , l e s s commonly, qu a r t z . S p h a l e r i t e does not c o n t a i n exsolved i r o n s u l p h i d e . Colour d e s c r i p t i o n s f o r s p h a l e r i t e and w u r t z i t e conform to the Munsell c o l o u r i d e n t i f i c a t i o n system (Goddard, e t a l . , 1963). 59 G r e y i s h y e l l o w w u r t z i t e e x i s t s l o c a l l y a t N a n i s i v i k main ore zone but i s not q u a n t i t a t i v e l y important. W u r t z i t e has not been d i s c o v e r e d a t Hawker Creek area. W u r t z i t e i s d i f f i c u l t t o d i s t i n g u i s h m i c r o s c o p i c a l l y from s p h a l e r i t e because i t has the same r e f l e c t i v i t y and medium l i g h t grey c o l o r . However, w u r t z i t e has a f i b r o u s h a b i t whereas s p h a l e r i t e does not and, under hi g h m a g n i f i c a t i o n and c r o s s e d n i c o l s , w u r t z i t e e x h i b i t s a c l e a r to g r e y i s h y e l l o w i n t e r n a l r e f l e c t i o n whereas s p h a l e r i t e i s i s o t r o p i c . The e x i s t e n c e of w u r t z i t e was confirmed by x-ray d i f f r a c t o m e t e r . W u r t z i t e abundance w i t h i n N a n i s i v i k main ore zone i s v a r i a b l e . I t e x i s t s i n some p o r t i o n s of the d e p o s i t and not i n others and, where p r e s e n t , i t e x i s t s i n some s u l p h i d e bands but not i n o t h e r s . No c o n s i s t e n t geographic d i s t r i b u -t i o n of w u r t z i t e i s apparent. W u r t z i t e e x i s t s commonly as a t h i n , f i b r o u s coat on dark r e d d i s h brown s p h a l e r i t e c r y s t a l s and u s u a l l y separates s p h a l e r i t e from s p a r r y dolomite. The c o n t a c t between s p h a l e r i t e and w u r t z i t e i s m e s o s c o p i c a l l y sharp but i s i r r e g u l a r under hi g h m a g n i f i c a t i o n , although w u r t z i t e does not appear to r e p l a c e s p h a l e r i t e . W u r t z i t e a l s o e x i s t s as a coat on p y r i t e c r y s t a l s and as i r r e g u l a r f i b r o u s masses or s p h e r u l i t e s i n s p a r r y dolomite. W u r t z i t e does not e x i s t where s p a r r y dolomite i s absent. However, a s p h a l e r i t e - s p a r r y dolomite a s s o c i a t i o n does not guarantee w u r t z i t e ' s presence. W u r t z i t e e x i s t s i n c o n t a c t w i t h p y r i t e , r e l i c t m a r c a s i t e or galena but does not r e p l a c e these m i n e r a l s . 60 T h i r t e e n samples of s p h a l e r i t e and one sample of w u r t z i t e were analyzed q u a n t i t a t i v e l y f o r i r o n content (Table IV; Appendix I ) . The i r o n content of s p h a l e r i t e i s TABLE IV IRON CONTENT OF ZINC.SULPHIDES L o c a t i o n Sample M i n e r a l Analyzed Iron Content i n Weight Per Cent FeS Content i n Mole Per C e n t 1 N a n i s i v i k A12 S p h a l e r i t e 2.05 3.56 main ore A22 S p h a l e r i t e 2.65 4.60 zone A27 Wurtzite 1.65 2.87 A33 S p h a l e r i t e 2.75 4.77 A34 S p h a l e r i t e 3.16 5.48 A38 S p h a l e r i t e 1.50 2. 61 A41 S p h a l e r i t e 2.80 4.86 A42 S p h a l e r i t e 6.20 10.70 A422 S p h a l e r i t e 6.40 11.04 A45 S p h a l e r i t e 1.65 2.87 Hawker Creek, Tl-35 S p h a l e r i t e 10.23 17.54 t r e n c h SH25-1 Occurrence CG4 S p h a l e r i t e 0.90 1.57 Occurrence JW3 S p h a l e r i t e 0.68 1.18 Occurrence MC3 S p h a l e r i t e 1.55 2. 70 Occurrence MC7 S p h a l e r i t e 0.93 1.62 v a r i a b l e and ranges from 0.68 weight per cent i r o n to 10.23 weight per cent i r o n . V a r i a t i o n i n i r o n content i s not c l o s e l y c o r r e l a t a b l e with c o l o r o f s p h a l e r i t e . C a b r i (1973) Mole per cent FeS i s computed from weight per cent i r o n . 2 Sample A42 was analyzed twice as a check on p r e c i s i o n . 61 analyzed two s p h a l e r i t e samples from N a n i s i v i k main ore zone by e l e c t r o n p r o b e m i c r o a n a l y s i s and found t h a t areas of low i r o n c o n c e n t r a t i o n , i . e . 0.25 to 0.6 weight per cent i r o n , e x i s t e d w i t h i n areas o f h i g h e r i r o n c o n c e n t r a t i o n , i . e . 6.0 to 7.5 weight per cent i r o n . C a b r i (1973) a l s o found t h a t s p h a l e r i t e c o n t a i n s 0.1 t o 0.3 weight per cent cadmium and n e g l i g i b l e manganese or indium. Galena i s much l e s s abundant than s p h a l e r i t e w i t h i n massive z i n c - l e a d d e p o s i t s . W i t h i n N a n i s i v i k main ore zone, galena comprises approximately 2 volume per cent of the t o t a l ore m i n e r a l and gangue content, although i n very g a l e n a - r i c h bands i t can range up to 20 volume per cent. Galena e x i s t s as i r r e g u l a r masses intergrown w i t h s p h a l e r i t e and/or p y r i t e , as v o i d - f i l l i n g between ot h e r m i n e r a l g r a i n s , and as c r y s t a l s . Galena c r y s t a l s range up to 0.4 inches i n diameter but most are l e s s than 0.1 inches i n diameter. Galena c r y s t a l forms comprise cubes {001} m o d i f i e d by o c t a h e d r a l corners {111}. Some c r y s t a l s are l a m e l l a r growth twinned and many c r y s t a l s are s k e l e t a l . Most galena c r y s t a l faces are etched, p i t t e d and i r r e g u l a r . Non-sulphide M i n e r a l s White s p a r r y dolomite i s the predominant non-sulphide m i n e r a l i n massive z i n c - l e a d d e p o s i t s . The s p a r r y dolomite content g e n e r a l l y ranges from zero volume per cent to 50 volume per cent and averages about 25 volume per cent. Sparry d o l o -mite e x i s t s commonly as f i n e - t o medium-grained, anhedral c r y s t a l s which are e i t h e r i r r e g u l a r l y intergrown with s u l p h i d e 62 m i n e r a l s or e x i s t i n d i s c r e t e bands inter-layered with s u l p h i d e s . Sparry dolomite a l s o e x i s t s w i t h i n s u l p h i d e zones as i r r e g u l a r , c r y s t a l l i n e masses up to a few f e e t i n diameter or as a c o a t -ing w i t h i n vugs. Sparry dolomite c r y s t a l s p r o j e c t i n g i n t o vugs are commonly coated by a l a t e - s t a g e , fine-grained,, s u c r o s i c dolomite. An unusual f e a t u r e of s p a r r y dolomite i s i t s t r i -boluminescence; when s t r u c k i t luminesces a b r i g h t r e d . Mole per cent c a l c i u m was determined f o r nine s p a r r y dolomite samples and f o r ten S o c i e t y C l i f f s Formation dolomite samples (Table V ) . I r o n , z i n c and manganese t r a c e element content were determined f o r twenty-six s p a r r y dolomite samples and f o r s i x S o c i e t y C l i f f s Formation dolomite samples (Table V I ) . The m a j o r i t y of S o c i e t y C l i f f s Formation dolomite samples were c o l l e c t e d w i t h i n one f o o t of s u l p h i d e d e p o s i t s . Sample l o c a t i o n s , sample d e s c r i p t i o n s and a n a l y t i c a l methods are summarized i n Appendix I. S o c i e t y C l i f f s Formation dolomite and s u l p h i d e d e p o s i t s p a r r y dolomite are not s t o c h i o m e t r i c CaMg(CO^^* Both dolomite v a r i e t i e s c o n t a i n about 51.0 mole per cent c a l c i u m and 49.0 mole per cent magnesium. Furthermore, Tables V and VI show t h a t the mole per cent c a l c i u m content of the two dolomite v a r i e t i e s are e s s e n t i a l l y i d e n t i c a l whereas the i r o n , z i n c and manganese t r a c e element contents are s t r i k i n g l y d i f f e r e n t . That i s , s p a r r y dolomite has higher median con-c e n t r a t i o n s o f i r o n , z i n c and manganese and a more extreme range of v a l u e s than does S o c i e t y C l i f f s Formation dolomite. 63 TABLE V MOLE PER CENT CALCIUM IN SPARRY DOLOMITE  AND SOCIETY CLIFFS FORMATION DOLOMITE Sample Location Mole per cent calcium Sparry Society C l i f f s dolomite Formation dolomite N a n i s i v i k Main Ore Zone Al East p o r t a l ; at 50.89 50.29 deposit margin A5 East p o r t a l ; at 50.81 50.78 deposit margin A25 East p o r t a l ; at 50.98 51.08 deposit margin A31 East p o r t a l ; at 51.45 51.11 deposit margin A37 East p o r t a l ; at 51.15 51.04 deposit margin A45 East p o r t a l ; at 50.33 51.25 deposit margin SSD11 Host dolomite near 51.19 west end of Nanis i v i k main ore zone Hawker Creek Tl-5 Trench SH25-1 50.81 51.30 Tl-48 Trench SH25-1 . 52.32 50.78 MC4 Occurrence MC4 5 0.96 51.60 Arithmetic Average 51.0 8 51.04 TABLE VI IRON, ZINC AND MANGANESE CONTENTS OF DOLOMITES Element Sparry dolomite (26^) Society C l i f f s Formation dolomite (6) Median (ppm) Range (ppm) Median (ppm) Range (pprnT Iron 724.5 306-4535 430.5 257-703 Zinc 196.5 13-6233 103.5 48-276 Manganese 855 168-2508 174 154-312 ^Number of samples analyzed are i n brackets. 64 C a l c i t e , a q u a n t i t a t i v e l y unimportant non-sulphide gangue, e x i s t s o n l y i n vugs w i t h i n s u l p h i d e d e p o s i t s . C a l c i t e occurs e i t h e r as c l e a r c a l c i t e rhombs t h a t are attached to o r overgrown on dolomite rhombs p r o j e c t i n g i n t o the vug, or as pale y e l l o w i s h , s i n g l y - or doubly-terminated, t a p e r i n g , 'barrel-shaped' c r y s t a l s . B arrel-shaped c r y s t a l s r a r e l y exceed 1 i n c h i n l e n g t h and are c h a r a c t e r i z e d by t h e i r c o n s i s t e n t c r y s t a l h a b i t ; major forms are {2131}, {4041} and {1011}, m o d i f i e d by {0112}, {0221} and {0881}. C a l c i t e c r y s t a l s sometimes c o n t a i n s m a l l euhedral c r y s t a l s of p y r i t e or p y r i t e pseudomorphs of m a r c a s i t e . Some ba r r e l - s h a p e d c a l c i t e c r y s t a l f aces are u n u s u a l l y 'etched'. The 'etch f i g u r e ' comprises a roughly c i r c u l a r , r i n g - l i k e , shallow groove which i s commonly accompanied by a s m a l l p i t i n the c e n t e r of the r i n g . The o r i g i n o f the e t c h f i g u r e s i s s p e c u l a t i v e but they may have formed by the a c t i o n of a c o r r o s i v e bubble of gas which etched a r i n g - l i k e groove where the bubble margin was i n c o n t a c t with the c r y s t a l f a c e . The s m a l l c e n t r a l p i t c o u l d have formed from a drop of c o r r o s i v e f l u i d t h a t remained a f t e r the bubble c o l l a p s e d . Pyrobitumen, a b l a c k , moderately hard, n o n v o l a t i l e substance w i t h c o n c h o i d a l f r a c t u r e , i s a common but q u a n t i t a -t i v e l y minor gangue. Pyrobitumen f i l l s v o i d s between s p a r r y dolomite o r s u l p h i d e m i n e r a l g r a i n s . A petroleum a l s o e x i s t s w i t h i n some sp a r r y dolomite as c l e a n s p a r r y dolomite samples d i s s o l v e d i n a beaker of 10 per cent HC1 s o l u t i o n commonly l e f t an o i l y f i l m . 65 Quartz e x i s t s i n s u l p h i d e d e p o s i t s as s m a l l , euhedral c r y s t a l s w i t h i n s p h a l e r i t e , s p a r r y dolomite or i n vugs w i t h c a l c i t e . Quartz i s q u a n t i t a t i v e l y unimportant but minor amounts do e x i s t a t s e v e r a l l o c a t i o n s w i t h i n N a n i s i v i k main ore zone and a t occurrence R02 near Hawker Creek (Figure 2). B a r i t e i s extremely r a r e w i t h i n s u l p h i d e d e p o s i t s and has been p o s i t i v e l y i d e n t i f i e d o n l y by x-ray d i f f r a c t o m e t e r . I t a p p a r e n t l y e x i s t s as f i n e c r y s t a l s w i t h i n some s p a r r y d o l o -mite as i t forms an i n s o l u b l e r e s i d u e i f the s p a r r y dolomite i s d i s s o l v e d . Gypsum e x i s t s w i t h i n some massive s u l p h i d e d e p o s i t s and occurs most commonly as white, i r r e g u l a r l y shaped masses of f i n e c r y s t a l s w i t h i n p y r i t e sand. Gypsum e x i s t s l e s s commonly as a 0.4 to 2 i n c h t h i c k , grey, p y r i t i f e r o u s gypsum zone at the margin of p y r i t e bodies or as s e l e n i t e c r y s t a l s up to 0.3 inches long a t t a c h e d to p y r i t e . Gypsum i s common w i t h i n s u l p h i d e d e p o s i t s t h a t crop out but i s q u a n t i t a t i v e l y n e g l i g i b l e to nonexistent- i n f r e s h l y exposed s u l p h i d e d e p o s i t s . T h i s i n d i c a t e s most gypsum i s secondary. N a t i v e sulphur e x i s t s i n some weathered s u l p h i d e d e p o s i t s but i s extremely r a r e . F a b r i c The m i c r o s c o p i c f a b r i c , i . e . t e x t u r e , of massive z i n c - l e a d d e p o s i t s i s uncomplicated. P y r i t e , p y r i t e pseudo-morphous a f t e r m a r c a s i t e , r e l i c t m arcasite and s p h a l e r i t e e x i s t commonly as subhedral to euhedral c r y s t a l s . P y r i t e and m a r c a s i t e were o f t e n d e p o s i t e d penecontemporaneously 66 because r e c o g n i z a b l e c r y s t a l h a b i t s o f each m i n e r a l f r e q u e n t l y e x i s t w i t h i n the same s u l p h i d e band. P y r i t e and marcasi t e are intergrown with s p h a l e r i t e but do not r e p l a c e i t , whereas s p h a l e r i t e commonly r e p l a c e s p y r i t e and ma r c a s i t e . Galena e x i s t s as c r y s t a l s but i s more common as f i l l between o t h e r m i n e r a l g r a i n s . The r e l a t i o n s h i p between p y r i t e and galena i s e q u i v o c a l because p y r i t e r e p l a c e s and i s r e p l a c e d by galena. The r e l a t i o n s h i p between s p h a l e r i t e and galena i s a l s o somewhat e q u i v o c a l but a mutual boundary i s the most common r e l a t i o n -s h i p . The c r y s t a l margins o f a l l s u l p h i d e minerals are f r e q u e n t l y corroded, p a r t i c u l a r l y where i n c o n t a c t w i t h s p a r r y dolomite. Sparry dolomite l o c a l l y r e p l a c e s s p h a l e r i t e , w u r t z i t e and galena. Sparry dolomite may r e p l a c e p y r i t e and r e l i c t m a r c a s i t e but the r e l a t i o n s h i p s are not c o n c l u s i v e . Quartz always e x i s t s as euhedral c r y s t a l s t h a t are e i t h e r i n vugs o r are e n c l o s e d i n s u l p h i d e and/or s p a r r y dolomite. Pyrobitumen always occ u p i e s the i n t e r s t i c e s between ot h e r m i n e r a l g r a i n s . C a l c i t e e x i s t s o n l y as euhedral c r y s t a l s i n vugs. C a l c i t e can e x i s t w i t h o r encl o s e p y r i t e , r e l i c t m a r c a s i t e o r s p h a l e r i t e but has not a p p r e c i a b l y r e p l a c e d o r been r e p l a c e d by these m i n e r a l s . The mesoscopic f a b r i c o f massive z i n c - l e a d d e p o s i t s i s d i v e r s e and commonly complex. Banded s t r u c t u r e i s the most s t r i k i n g mesoscopic f a b r i c but f e a t u r e l e s s , monomineralic zones and i r r e g u l a r l y intergrown, h e t e r o m i n e r a l i c zones a l s o e x i s t . F i f t e e n ' f a b r i c v a r i e t i e s ' e x i s t w i t h i n the massive z i n c - l e a d d e p o s i t exposed i n tr e n c h SH25-1 at Hawker Creek 67 ( T a b l e V I I ; F i g u r e 6). F a b r i c v a r i e t i e s a r e d i s t i n g u i s h e d on t h e b a s i s o f m i n e r a l o g y and m e s o s c o p i c s t r u c t u r e . F u r t h e r -more, f a b r i c v a r i e t i e s a r e s e p a r a t e d i n t o t h r e e c l a s s e s on t h e b a s i s o f w h e t h e r p y r i t e , s p h a l e r i t e o r s p a r r y d o l o m i t e i s most a b u n d a n t . The c o n t a c t s between t h e v a r i o u s f a b r i c v a r i e t i e s r a n g e f r o m s h a r p t o g r a d a t i o n a l ( F i g u r e 6). S i m i l a r f a b r i c v a r i e t i e s a l s o e x i s t w i t h i n N a n i s i v i k m a i n o r e zone and w i t h i n o t h e r m a s s i v e s u l p h i d e d e p o s i t s . Banded s t r u c t u r e c o m p r i s e s p a r a l l e l o r s u b - p a r a l l e l bands d i f f e r i n g e i t h e r i n c o m p o s i t i o n a n d / o r m i c r o s c o p i c f a b r i c . The t h i c k n e s s o f i n d i v i d u a l bands r a n g e s f r o m 0.2 t o 0.8 i n c h e s (5 m i l l i m e t e r s t o 2 c e n t i m e t e r s ) b u t u s u a l l y i s l e s s t h a n 0.0.4 i n c h e s (1 m i l l i m e t e r ) . S u l p h i d e i n t e r l a y e r e d w i t h s p a r r y d o l o m i t e i s t h e most common t y p e o f banded s t r u c t u r e ( P l a t e s V I I I . a and V I I I . b ) . A s u l p h i d e band o v e r l a i n by a s p a r r y d o l o m i t e band c o m p r i s e s a s u l p h i d e - s p a r r y d o l o m i t e ' c o u p l e t 1 . The f a b r i c o f i n d i v i d u a l s u l p h i d e o r s p a r r y d o l o m i t e bands w i t h i n a c o u p l e t i s commonly i r r e g u l a r b e c a u s e o f m i n e r a l i n t e r g r o w t h a t band m a r g i n s . Banded s t r u c t u r e a l s o e x i s t s i n some z o n e s c o m p r i s e d s o l e l y o f p y r i t e and m a r c a s i t e ( P l a t e I X ) . Banded s t r u c t u r e i n t h i s c a s e i s due t o v a r i a t i o n i n g r a i n s i z e a n d / o r i n p o r o s i t y . P o r o s i t y i n b anded i r o n s u l p h i d e commonly i n c r e a s e s as g r a i n s i z e d e c r e a s e s . The f i n e - g r a i n e d and h i g h l y p o r o u s i r o n s u l p h i d e bands c o m p r i s e a m e l n i k o v i t e (Dana, 1944; Ramdohr, 1969) t y p e o f p y r i t e . Banded i r o n s u l p h i d e i s commonly so e v e n l y and u n i f o r m l y banded t h a t t h e r o c k a p p e a r s ' l a m i n a t e d ' 68 TABLE V I I FABRIC VARIETIES WITHIN MASSIVE ZINC-LEAD DEPOSITS Ma j o r M i n e r a l Symbol D e s c r i p t i o n P y r i t e P_ Banded p y r i t e (90%) bands a r o . i p p r o x i -m a t e r l y 1 mm t h i c k ; c o n t a c t s between bands a r e s h a r p and even; s p h a l e r i t e (5-10%) o c c u r s as s m a l l c r y s t a l s (0.5 nun) i n bands p a r a l l e l t o p y r i t e b a n d i n g . P 7 Banded p y r i t e ( g r e a t e r than 9 8 % ) ; bands a r e u s u a l l y l e s s t h a n 5' mm t h i c k and a v e r a g e 1 t o 2 mm t h i c k ; c o n t a c t s between bands a r e s h a r p and even; minor v i s i b l e s p h a l e r i t e and w h i t e s p a r r y d o l o m i t e . Pg I r r e g u l a r l y i n t e r g r o w n (nonbanded) p y r i t e and w h i t e s p a r r y d o l o m i t e (may i n some c a s e s • . !. be p y r i t e v a r i e t y P 7 b r e c c i a t e d t h e n cemented by s p a r r y d o l o m i t e ) . .P5 Banded p y r i t e (70%) w i t h l e n s e s o f w h i t e s p a r r y d o l o m i t e . P 4 Banded p y r i t e (50%) and w h i t e s p a r r y d o l o -m i t e ( 5 0 % ) ; bands a v e r a g e 4 mm t h i c k ; p y r i t e bands a r e h e t e r o g e n e o u s , i . e . p y r i t e o c c u r s as i r r e g u l a r masses a l o n g a p a r t i c u -l a r band. P 3 Banded t o m a s s i v e p y r i t e (75%) w i t h i r r e g u -l a r i n t e r b a n d s o r i n t e r g r o w n masses o f s p h a l e r i t e (5-20%) and w h i t e s p a r r y d o l o m i t e . P2 M a s s i v e p y r i t e ; no v i s i b l e s p h a l e r i t e . P^ P y r i t e sand. S p h a l e r i t e S 4 C o a r s e c r y s t a l s (up' t o 1 cm) o f s p h a l e r i t e (30-50%) i n t e r g r o w n (nonbanded) w i t h w h i t e s p a r r y d o l o m i t e . S 3 Banded c o a r s e c r y s t a l l i n e (up t o 5 mm) s p h a l e r i t e (40-60%) and w h i t e s p a r r y d o l o m i t e . S 2 Banded c o a r s e c r y s t a l l i n e s p h a l e r i t e and w h i t e s p a r r y d o l o m i t e (as S 3 ) w i t h i n t e r -grown c r y s t a l s o f g a l e n a (10-20%). Si Banded s p h a l e r i t e (to 6 0 % ) , p y r i t e (20% o r more) and w h i t e s p a r r y d o l o m i t e ; Bands a v e r a g e 2 mm t h i c k . S p a r r y D o l o m i t e D 3 White s p a r r y bands and/or s p h a l e r i t e . d o l o m i t e w i t h minor i r r e g u l a r masses o f p y r i t e and/or D2 C h a o t i c t o i r r e g u l a r l y i n t e r g r o w n s p h a l e r i t e ( 3 0 % ) , p y r i t e (40%) and w h i t e s p a r r y d o l o -m i t e . May i n p a r t be o t h e r s u l p h i d e v a r i e t i e s b r e c c i a t e d and recemented by w h i t e s p a r r y d o l o m i t e . White s p a r r y d o l o m i t e . m i n e r a l Volume p e r c e n t volume e x i s t i n g i n ( v i s u a l l y e s t i m a t e d ) the f a b r i c v a r i e t y . o f the t o t a l 69 (Plate I X ) . Elsewhere, and p a r t i c u l a r l y between s u l p h i d e -s p a r r y dolomite c o u p l e t s , s u l p h i d e bands or i n d i v i d u a l s u l p h i d e c r y s t a l s are commonly t r u n c a t e d by. o v e r l y i n g s u l p h i d e or s p a r r y dolomite bands. A l t e r n a t i v e l y , s u l p h i d e c r y s t a l s can be p o o r l y formed downwards but terminate w i t h w e l l developed c r y s t a l f a c e s upwards. Banded s t r u c t u r e i s g e n e r a l l y h o r i z o n t a l . I n d i v i d u a l bands or s u l p h i d e - s p a r r y dolomite c o u p l e t s are commonly l a t e r -a l l y continuous f o r s e v e r a l yards but a l s o can change composition r a p i d l y or terminate a b r u p t l y . Anastomosing bands e x i s t but are uncommon. S e v e r a l i n t e r l a y e r e d bands of r e p e t i t i o u s composition, f o r example p y r i t e i n t e r l a y e r e d - with; sparry;; dolomite, can form a u n i t which d i f f e r s i n gross composition from over-l y i n g and u n d e r l y i n g u n i t s (Figure 6). Such u n i t s commonly range from a few inches to a few f e e t t h i c k and are l a t e r a l l y continuous f o r s e v e r a l y a r d s . However, i n d i v i d u a l bands w i t h i n a u n i t are not n e c e s s a r i l y t h a t continuous. Other, unusual s t r u c t u r e s a l s o e x i s t w i t h i n massive s u l p h i d e d e p o s i t s . These s t r u c t u r e s are: onlap, c r o s s -s t r a t i f i c a t i o n , c u t - a n d - f i l l , s u l p h i d e b r e c c i a and s t a l a c t i t i c p y r i t e - m a r c a s i t e . Not a l l of these s t r u c t u r e s e x i s t a t every d e p o s i t or even at more than one l o c a t i o n w i t h i n a d e p o s i t . Onlap e x i s t s w i t h i n s u l p h i d e d e p o s i t s a t both N a n i s i v i k and Hawker Creek areas. Onlap comprises a s u l p h i d e and/or s p a r r y dolomite band t r a n s g r e s s e d by the next o v e r l y i n g band (Figures 6 and 7). Onlapping band t e r m i n a t i o n s can 70 PLATE V I I I . a Sulphide i n t e r l a y e r e d w i t h s p a r r y dolomite. Specimen c o l l e c t e d a t N a n i s i v i k main ore zone. PLATE V I I I . b H o r i z o n t a l l y banded s u l p h i d e and s p a r r y d o l o m i t e forming an ore zone about 4 f e e t t h i c k . The y e l l o w m i n e r a l i s p y r i t e , the brown m i n e r a l i s s p h a l e r i t e and the white m i n e r a l i s s p a r r y d o l o m i t e . The s u l p h i d e zone i s o v e r l a i n and u n d e r l a i n by S o c i e t y C l i f f s Formation d o l o m i t e . The zone i s a t 1,900 North C r o s s - c u t , N a n i s i v i k main o r e zone (see F i g u r e 8 f o r l o c a t i o n o f 1,900 North C r o s s - c u t ) . 71 ' SYMBOLS . Angular unconformity (defined, approximate, very approximate) Banded structure (defined, approximate, very approximate) , ,Pencil ....... PLATE IX Banded structure i n P7 fa b r i c v a r i e t y of pyr i t e that e x i s t s i n trench SH25-1 at Hawker Creek (Figure 6). Note the c r o s s - s t r a t i f i c a t i o n present. The white, v e r t i c a l object i s a p e n c i l for scale. The diagram below the plate i l l u s -trates the geological relationships present. SCALE FEET FIGURE 7: GEOLOGY, TRENCH SH25-2, HAWKER CREEK. o v e r l i e e i t h e r S o c i e t y C l i f f s Formation dolomite or p r e v i o u s l y d e p o s i t e d ore minerals and gangue. C r o s s - s t r a t i f i c a t i o n e x i s t s a t Hawker Creek and a t s e v e r a l l o c a t i o n s w i t h i n N a n i s i v i k main ore zone. C r o s s -s t r a t i f i c a t i o n v a r i e s i n s c a l e and i n the m i n e r a l o g i c a l compos t i o n o f c r o s s - c u t t i n g bands. For example, i n tr e n c h SH25-1 at Hawker Creek, a u n i t o f very evenly banded p y r i t e i s t r u n c a t e d by an o v e r l y i n g banded p y r i t e (Plate I X ) . T h i s phenomena i s repeated s e v e r a l times over a v e r t i c a l i n t e r v a l o f about 1.5 f e e t and o v e r l y i n g banded p y r i t e always t r u n c a t e s s t r a t i g r a p h i c a l l y lower banded p y r i t e (Figure 6). E x c e l l e n t examples of c r o s s - s t r a t i f i c a t i o n a l s o e x i s t a t N a n i s i v i k main ore zone (P l a t e s X.a, X.b and X I ) . C u t - a n d - f i l l s t r u c t u r e comprises h o r i z o n t a l l y banded s u l p h i d e s w i t h or without s p a r r y dolomite i n which a p a l e o -trough i s now f i l l e d by c r y s t a l l i n e , i . e . not d e t r i t a l , s u l p h i d e w i t h o r without s p a r r y dolomite. Banding i n the o v e r l y i n g 'chemical sediment' p a r a l l e l s the disconformable c o n t a c t which e x i s t s between the two u n i t s . A mesoscopic example of c u t - a n d - f i l l s t r u c t u r e e x i s t s i n t r e n c h SH25-1 at Hawker Creek (Figure 6; P l a t e s XII.a and X l l . b ) . A l a r g e example o f c u t - a n d - f i l l s t r u c t u r e e x i s t s i n the e a s t e r n underground workings at N a n i s i v i k main ore zone (Figure 8; P l a t e X.b). There, a pa l e o t r o u g h , which i s s e v e r a l tens of f e e t wide and i s f i l l e d w ith P3 f a b r i c v a r i e t y o f p y r i t e , i s cut i n t o a sequence of h o r i z o n t a l l y banded ore which i s 74 s e v e r a l f e e t t h i c k . T h i s megascopic c u t - a n d - f i l l s t r u c t u r e i s exposed i n s e v e r a l c r o s s - c u t s o f f the main d r i f t and i s t r a c e -able f o r a t l e a s t 600 f e e t . Sulphide b r e c c i a comprises angular t o subrounded c l a s t s o f s u l p h i d e , cemented by s u l p h i d e and/or by s p a r r y dolomite. Sulphide b r e c c i a e x i s t s w i t h i n massive s u l p h i d e d e p o s i t s a t N a n i s i v i k , Hawker Creek and C h r i s Creek but i s v o l u m e t r i c a l l y unimportant a t a l l d e p o s i t s . Sulphide b r e c c i a at the e a s t end of N a n i s i v i k main ore zone comprises s u l p h i d e c l a s t s , which range up to s e v e r a l inches i n diameter, cemented by p y r i t e , s p h a l e r i t e and s p a r r y dolomite (Plate X H I . a ) . T h i s b r e c c i a zone e x i s t s a t a l o c a l e where the f o o t w a l l c o n t a c t between the massive s u l p h i d e d e p o s i t and the u n d e r l y i n g S o c i e t y C l i f f s Formation dolomite a b r u p t l y changes r e l i e f . Sulphide b r e c c i a e x i s t s i n a somewhat s i m i l a r s e t t i n g i n t r e n c h SH25-1 at Hawker Creek (Figure 6). At Twin Lakes Creek and C h r i s Creek p y r i t e b o d i e s , however, s u l p h i d e b r e c c i a , which i s comprised of p y r i t e c l a s t s cemented by p y r i t e , e x i s t l o c a l l y w i t h i n and a t the margins o f the d e p o s i t s . P y r i t e - m a r c a s i t e s t a l a c t i t e s existed''" i n a c a v i t y w i t h i n Twin Lakes Creek p y r i t e body (P l a t e s XIII.b and X I I I . c ) . The s t a l a c t i t e s are up to 0.4 inches wide by 10 inches long and hang v e r t i c a l l y from t h e i r o r i g i n on the c a v i t y r o o f . The space between some s t a l a c t i t e s i s p a r t i a l l y f i l l e d by p y r i t e . T h i s specimen i s now a t the U n i v e r s i t y o f B r i t i s h Columbia i n the Department of Geology museum. 75 PLATE X.a C r o s s - s t r a t i f i c a t i o n at 1,700 North Cross-cut, Nanisivik main ore zone. Regularly laminated a l g a l dolomite of Society C l i f f s Formation (bottom), dipping northerly (to the r i g h t ) , i s overlain by banded sulphide and sparry dolomite that i s truncated by an overlying unit of banded sulphide and sparry dolomite. The whitish coating on portions of the rock surface i s f r o s t . PLATE X.b Horizontally banded sulphide and sparry dolomite at 2,100 North Cross-cut, Nanisivik main ore zone, i s truncated by southerly dipping (to the l e f t ) , 'crudely' banded p y r i t e and s p h a l e r i t e , forming a large c r o s s - s t r a t i f i e d structure. This feature i s repeated i n 2,100 South Cross-cut with the exception that the crudely banded p y r i t e and sphalerite dips northerly. In t o t a l the structure appears to be a large c u t - a n d - f i l l . 76 PLATE XI C r o s s - s t r a t i f i c a t i o n a t 2,100 South C r o s s -cut, N a n i s i v i k main ore zone. At t h i s l o c a l e the b l o c k o f S o c i e t y C l i f f s Formation dolomite (the b l a c k rock a t the c e n t e r of the p l a t e ) appears t o be a ' f l o a t i n g ' b l o c k . However, bedding i n t h i s f l o a t i n g b l ock i s a t the same a t t i t u d e as i n the u n d e r l y i n g h o s t dolomite, hence the b l o c k i s , i n f a c t , a t t a c h e d . Note t h a t the top o f t h i s b l o c k , as w e l l as the ' o v e r l a p p i n g ' banded s u l p h i d e and s p a r r y dolomite, i s t r u n c a t e d by the o v e r l y i n g , h o r i z o n t a l banded s u l p h i d e and s p a r r y d o l o m i t e . The diagram below the p l a t e i l l u s t r a t e s the g e o l o g i c a l r e l a t i o n s h i p s p r e s e n t . PLATE X I I . a C u t - a n d - f i l l s t r u c t u r e i n t r e n c h SH25-1 a t Hawker Creek. Banded s p h a l e r i t e and s p a r r y d o l o m i t e (S3 f a b r i c v a r i e t y ) a r e o v e r l a i n by banded p y r i t e (P7 f a b r i c v a r i e t y ) . A PLATE X l l . b C u t - a n d - f i l l s t r u c t u r e i n tr e n c h SH25-1 at Hawker Creek. A clos e - u p o f P l a t e X I I . a . SECTION 55,600 E SECTION 59,271 E SECTION 63,527 E 79 PLATE XIII.a Sulphide breccia at 1,900 South Cross-cut, Nanisivik main ore zone, i s underlain by Society C l i f f s Formation dolomite (lower l e f t and bottom) and overlain by hori z o n t a l l y banded s u l -phide. The height of the exposure in the plate i s approximately f i v e feet. PLATE XIII.b PLATE XIII.c Sulphide s t a l a c t i t e s at Twin Lakes Creek p y r i t e zone. The height of the exposure i n Plate XIII.b i s approxi-mately ten inches. The s t a l a c t i t e s i n Plate XIII.c are the two at the l e f t hand side of Plate XIII.b. 80 B o t r y o i d a l and marrvrnillary p y r i t e e x i s t e d w i t h i n t h e c a v i t y b u t p y r i t e s t a l a g m i t e s were n o t p r e s e n t . S t a l a c t i t e s do n o t h a v e ' c l a s s i c a l ' s t a l a c t i t e s t r u c t u r e ; i . e . a h o l l o w , c e n t r a l t u b e w i t h c o n c e n t r i c g r o w t h l a y e r s i s l a c k i n g . I n s t e a d , t h e s t a l a c -t i t e , i n c r o s s s e c t i o n , c o m p r i s e s a p o r o u s c o r e o f f i n e - g r a i n e d , l o o s e l y i n t e r l o c k i n g p y r i t e c r y s t a l s s u r r o u n d e d by a zone o f t i g h t l y i n t e r g r o w n , m e d i u m - g r a i n e d , o u t w a r d p r o j e c t i n g c r y s t a l s o f p y r i t e pseudomorphous a f t e r m a r c a s i t e . C r y s t a l t e r m i n a t i o n s a t t h e s t a l a c t i t e o u t e r s u r f a c e a r e commonly c o r r o d e d and l o c a l l y a r e o v e r g r o w n by s m a l l , c l e a r , e u h e d r a l s e l e n i t e c r y s t a l s . S u l p h i d e s t a l a c t i t e s a r e r a r e and have n o t been d i s c o v e r e d w i t h i n o t h e r m a s s i v e s u l p h i d e d e p o s i t s a t n o r t h B a f f i n I s l a n d . C o n t a c t R e l a t i o n s h i p s The m a j o r i t y o f m a s s i v e z i n c - l e a d d e p o s i t s a r e i n c o n t a c t w i t h d o l o m i t e o f S o c i e t y C l i f f s F o r m a t i o n ; c o n t a c t s w i t h s h a l e o r l i m e s t o n e o f V i c t o r Bay F o r m a t i o n e x i s t l o c a l l y . The c o n t a c t s between m a s s i v e z i n c - l e a d d e p o s i t s and S o c i e t y C l i f f s F o r m a t i o n a r e g e n e r a l l y a b r u p t ( P l a t e s XIV.a and X l V . b ) . S u l p h i d e d i s s e m i n a t e d i n and r e p l a c i n g t h e h o s t d o l o m i t e r a p i d l y d e c r e a s e s away f r o m t h e c o n t a c t and i s v i r t u a l l y n o n e x i s t e n t a few i n c h e s f r o m t h e c o n t a c t . C a r b o n a c e o u s l a y e r s s e p a r a t i n g d o l o m i t e l a m i n a e w i t h i n t h e h o s t d o l o m i t e have commonly been s e l e c t i v e l y r e p l a c e d b e c a u s e s u l p h i d e g r a i n s a r e more a b u n d a n t and e x i s t f a r t h e r f r o m t h e c o n t a c t i n t h e c a r b o n a c e o u s l a m i n a e t h a n do s u l p h i d e g r a i n s 81 i n the dolomite laminae. However, most banded s t r u c t u r e w i t h i n massive z i n c - l e a d d e p o s i t s i s not due to s e l e c t i v e replacement of the laminated host dolomite because the a t t i t u d e o f the two s t r u c t u r e s i s g e n e r a l l y d i f f e r e n t . For example, a t N a n i s i v i k main ore zone bedding w i t h i n S o c i e t y C l i f f s Formation d i p s g e n e r a l l y 15 degrees n o r t h e r l y and i s t r u n c a t e d a t the d e p o s i t margins by f l a t - l y i n g banded s u l p h i d e and s p a r r y dolomite (Plate XIV.a). Other examples o f d i p p i n g S o c i e t y C l i f f s Formation dolomite t h a t a r e . t r u n c a t e d by f l a t -l y i n g banded s u l p h i d e and s p a r r y dolomite, e x i s t a t Hawker Creek (Figures 6 and 7) and C h r i s Creek. At the margins o f Twin Lakes Creek p y r i t e zone, p y r i t e w i t h i n the host dolomite e x i s t s as r a r e disseminated c r y s t a l s a few inches from the c o n t a c t and g r a d u a l l y i n c r e a s e s i n abundance u n t i l h ost d o l o -mite immediately adjacent to the c o n t a c t i s completely r e p l a c e d . One hundred per cent replacement of the host dolomite near the c o n t a c t i s i n d i c a t e d because banding w i t h i n t h i s replacement p y r i t e has an i d e n t i c a l a t t i t u d e to t h a t of n o n - h o r i z o n t a l bedding w i t h i n the host dolomite, whereas the a t t i t u d e o f banded s t r u c t u r e w i t h i n the remainder of the p y r i t e body i s h o r i z o n t a l . C l a s t s of d i s p l a c e d S o c i e t y C l i f f s Formation d o l o -mite are uncommon w i t h i n the massive z i n c - l e a d d e p o s i t s . Most ' f l o a t i n g ' b l o c k s of host dolomite have the same bedding a t t i t u d e as the surrounding country rock (Figure 6) and t h e r e -f o r e are 'attached' a t some p o i n t . However, d i s p l a c e d c l a s t s of host dolomite do e x i s t l o c a l l y . For example, at Twin Lakes 82 PLATE XIV.a Contact between northerly dipping (to the r i g h t ) , regularly laminated a l g a l dolomite of Society C l i f f s Formation (lower portion of the plate) and h o r i z o n t a l l y banded sulphide and sparry dolomite. Plate taken at 1,900 South Cross-cut, Nanisivik main ore zone. The distance across the base of the plate i s approximately two feet. PLATE XlV.b Contact between regularly laminated a l g a l dolomite of Society C l i f f s Formation (to the l e f t ) and banded p y r i t e and sparry dolomite i n trench SH25-2, Hawker Creek (see Figure 7 for the exact location of the p l a t e ) . 83 C r e e k p y r i t e z one, d i s p l a c e d c l a s t s o f S o c i e t y C l i f f s F o r m a t i o n d o l o m i t e up t o a y a r d i n l e n g t h a r e cemented by s p a r r y d o l o -m i t e and p y r i t e . T hese c l a s t s e x i s t m a i n l y n e a r t h e m a r g i n s o r t o p o f t h e p y r i t e body and have n o t moved f a r f r o m t h e i r o r i g i n a l p o s i t i o n , i . e . t h e y do n o t f o r m a r u b b l e b r e c c i a . S o c i e t y C l i f f s F o r m a t i o n i s a l t e r e d a t some c o n t a c t s w i t h s u l p h i d e d e p o s i t s . D u r i n g a l t e r a t i o n , r e g u l a r l y l a m i n a t e d a l g a l d o l o m i t e was r e c r y s t a l l i z e d t o a m e d i u m - g r a i n e d , e q u i -g r a n u l a r d o l o m i t e and t h e l a m i n a t e d s t r u c t u r e was o b l i t e r a t e d by a homogeneous r e d i s t r i b u t i o n o f c a r b o n a c e o u s m a t t e r w h i c h was o r i g i n a l l y c o n c e n t r a t e d between t h e d o l o m i t e l a m i n a e . A l t e r a t i o n d i d n o t c a u s e a change i n t h e c o l o r o f t h e h o s t d o l o m i t e o r p r o d u c e new m i n e r a l s w i t h t h e e x c e p t i o n o f t h e m i n o r amounts o f d i s s e m i n a t e d s u l p h i d e t h a t were i n t r o d u c e d . The t r a c e e l e m e n t d i s t r i b u t i o n i n h o s t d o l o m i t e a d j a c e n t t o o r e b o d i e s has n o t been s t u d i e d a d e q u a t e l y . Bradshaw (1970) c o n d u c t e d an o r i e n t a t i o n r o c k g e o c h e m i c a l s u r v e y a t N a n i s i v i k and f o u n d t h a t anomalous c o n c e n t r a t i o n s o f z i n c , l e a d a n d / o r c o p p e r e x i s t i n h o s t d o l o m i t e o n l y w i t h i n 6 f e e t o f N a n i s i v i k main o r e zone ( A p p e n d i x I I I ) . A t Hawker C r e e k , f i v e g e o c h e m i c a l r o c k samples o f h o s t d o l o m i t e w h i c h were c o l l e c t e d w i t h i n one f o o t o f a z i n c - r i c h s u l p h i d e d e p o s i t , a s s a y e d 0.03 t o 1.70 p e r c e n t z i n c , 0.05 t o 0.6 0 p e r c e n t l e a d and t r a c e c o p p e r ( F i g u r e 6 ) . A t b o t h N a n i s i v i k and Hawker C r e e k , r o c k s a m p l e s o f h o s t d o l o m i t e w h i c h were c o l l e c t e d more t h a n a few f e e t f r o m t h e m a s s i v e s u l p h i d e d e p o s i t g e n e r a l l y c o n t a i n e d b a c k g r o u n d m e t a l 84 c o n c e n t r a t i o n s , i . e . 5 to 30 p a r t s per m i l l i o n z i n c and 5 to 30 p a r t s per m i l l i o n l e a d (Appendix I I I ) . These data i n d i c a t e t h a t z i n c and l e a d were not s i g n i f i c a n t l y d i s p e r s e d away from the main s i t e of s u l p h i d e d e p o s i t i o n . Massive z i n c - l e a d d e p o s i t s i n c o n t a c t w i t h V i c t o r Bay Formation e x i s t l o c a l l y a t Nanisivik,.and a t White Bay- area. At N a n i s i v i k , V i c t o r Bay Formation d i r e c t l y o v e r l i e s p o r t i o n s of the west end of N a n i s i v i k main ore zone (Figure 4). The c o n t a c t was not exposed at s u r f a c e but has been i n t e r s e c t e d by s e v e r a l diamond d r i l l h o l e s (Watts, G r i f f i s and McOuat, 197 3) and i s exposed underground i n some of the development d r i f t s completed d u r i n g 1975. Although V i c t o r Bay Formation crops out over an e x t e n s i v e area a t the west end of N a n i s i v i k main ore zone, diamond d r i l l i n g has shown t h a t i t d i r e c t l y o v e r l i e s the s u l p h i d e d e p o s i t o n l y l o c a l l y and t h a t a t h i n t o t h i c k zone of dolomite e x i s t s between V i c t o r Bay Formation and the s u l p h i d e d e p o s i t a t many p l a c e s . The l a r g e s t area o f s u l p h i d e d e p o s i t d i r e c t l y o v e r l a i n by V i c t o r Bay Formation i s probably no more than 150 f e e t wide by 700 f e e t l o n g . The dolomite which e x i s t s l o c a l l y between V i c t o r Bay Forma-t i o n and the s u l p h i d e d e p o s i t i s g e n e r a l l y S o c i e t y C l i f f s Formation dolomite, but i n some p l a c e s , p a r t i c u l a r l y where the dolomite i s t h i n and i t s c o n t a c t with shale d i f f u s e , i t may be d o l o m i t i z e d V i c t o r Bay Formation. Although the c o n t a c t between the s u l p h i d e d e p o s i t and V i c t o r Bay Formation i s a p p a r e n t l y . a f a u l t c o n t a c t i n a few p l a c e s , elsewhere i t i s not because i t i s not sharp and l o c a l l y i s even g r a d a t i o n a l . 85 Shale fragments e x i s t l o c a l l y w i t h i n the s u l p h i d e d e p o s i t up to 2.3 f e e t away from the c o n t a c t and s h a l e e x i s t i n g up to tens of f e e t above the c o n t a c t with the s u l p h i d e d e p o s i t i s commonly m i n e r a l i z e d by p y r i t e , s p h a l e r i t e or carbonate"*" which e x i s t as f i s s u r e - f i l l , as masses up to a few inches t h i c k p a r a l l e l i n g bedding, and as d i s s e m i n a t i o n s w i t h i n the host rock (Texasgulf Inc., 1962). An o x i d i z e d zone, rubble zone o r o t h e r evidence of e r o s i o n are not p r e s e n t a t the c o n t a c t between shale and the massive z i n c - l e a d d e p o s i t . V i c t o r Bay Formation i n c o n t a c t with a s u l p h i d e d e p o s i t a l s o e x i s t s 1.5 m i l e s n o r t h e a s t e r l y of the west end of N a n i s i v i k main ore zone. L i t t l e i s known about the c o n t a c t at t h i s l o c a l e as i t has been i n t e r s e c t e d i n o n l y a few 2 diamond d r i l l h o l e s . A t White Bay area (Figure 2), the c o n t a c t between a massive s u l p h i d e d e p o s i t and V i c t o r Bay Formation limestone """During the e a r l y phases of diamond d r i l l i n g a t N a n i s i v i k , Texasgulf Inc. personnel c o n s i s t e n t l y r e f e r r e d to any white s p a r r y carbonate i n core as ' c a l c i t e 1 , a p p a r e n t l y to d i f f e r e n t i a t e i t from S o c i e t y C l i f f s Formation dolomite. However, a l l the 'carbonate' s t r i n g e r s e x i s t i n g i n S o c i e t y C l i f f s Formation t h a t were examined by the author comprise white s p a r r y dolomite. C a l c i t e s t r i n g e r s and v e i n s do e x i s t i n V i c t o r Bay Formation but s u l p h i d e has not been noted i n such c a l c i t e v e i n s . U n f o r t u n a t e l y , t h i s e a r l y p r a c t i c e of l a b e l l i n g a l l carbonate s t r i n g e r s as c a l c i t e s t r i n g e r s has been perpetuated by some l a t e r workers. Thus, one cannot a c c u r a t e l y determine from diamond d r i l l hole logs whether r e p o r t e d ' c a l c i t e ' s t r i n g e r s c u t t i n g V i c t o r Bay Formation are , i n a c t u a l f a c t , c a l c i t e or are white sp a r r y dolomite. I t i s probable t h a t most of the ' c a l c i t e ' s t r i n g e r s r e p o r t e d as c u t t i n g V i c t o r Bay Formation and c o n t a i n i n g s u l p h i d e , are white sp a r r y dolomite. Texasgulf Inc. (1962), unpublished diamond d r i l l hole l o g s and v e r t i c a l s e c t i o n T3 900W. 86 was not examined because the d e p o s i t i s exposed o n l y on an i n a c c e s s i b l e c l i f f . D i s t r i b u t i o n , Trend, Shape and Sulphide V a r i a t i o n o f Deposits  N a n i s i v i k Area At l e a s t twenty massive s u l p h i d e d e p o s i t s crop out or e x i s t as suboutcrop at N a n i s i v i k area (Figure 4). The t r e n d and shape o f s u l p h i d e d e p o s i t s , with the e x c e p t i o n of N a n i s i v i k main ore zone, are not w e l l known at p r e s e n t . C o n f i g u r a t i o n of N a n i s i v i k main ore zone i s b e t t e r known because o f g r i d diamond d r i l l i n g conducted along the a x i s o f the body (Watts, G r i f f i s and McOuat, 1973). N a n i s i v i k main ore zone can be d e s c r i b e d g e n e r a l l y as an e a s t e r l y t r e n d i n g , ribbon-shaped manto u n d e r l a i n , a t l e a s t i n some l o c a t i o n s , by a ' s u b - v e r t i c a l k e e l ' (Figure 8). The manto i s sinuous i n p l a n view because i t comprises numerous a d j o i n i n g segments, ranging commonly from 400 to 800 f e e t i n l e n g t h , which are a b r u p t l y d i f f e r e n t i n t r e n d . The trends of the v a r i o u s segments are not random. The commonest segment t r e n d i s 090°, whereas 035°, 073°, 115° to 120°, 145° and 180° are l e s s common. Twin Lakes p y r i t e zone, which may be a continuance o f the western end of N a n i s i v i k main ore zone, trends southeast at i t s n o r t h end and south a t i t s south end. The t r e n d o f o t h e r s u l p h i d e d e p o s i t s , i n t e r p r e t e d from s p a t i a l d i s t r i b u t i o n of s u l p h i d e outcrops and from g e o p h y s i c a l anom-a l i e s (Figure 4; Appendix I I I ) , i s e a s t e r l y . The r e l a t i o n s h i p of the v a r i o u s s u l p h i d e d e p o s i t s a t N a n i s i v i k i s complicated 87 by f a u l t i n g but g e o p h y s i c a l surveys i n d i c a t e t h a t the d e p o s i t s converge t o the west. The manto has a t r u e width ranging from 300 f e e t a t i t s e a s t e r n end to 650 f e e t . a t i t s western end. The t r u e t h i c k n e s s of the manto ranges most commonly from 2 0 to 40 f e e t but i s l o c a l l y up to 60 f e e t . The l e n g t h of the manto, measured along i t s a x i s , i s a t l e a s t 9,500 f e e t between c o o r d i n a t e s 55,000E, 51,000N and 64 ,150E, 51,800N. I f N a n i s i v i k main ore zone c o n t i n u e s to the south i n t o Twin Lakes p y r i t e zone and to the e a s t i n t o Ocean View d e p o s i t or E a s t e r n Extension-Kuhulu Camp anomaly, then the l e n g t h o f t h i s continuous s u l p h i d e body would be g r e a t e r than 5 m i l e s . The l a r g e manto p o r t i o n o f N a n i s i v i k main ore zone i s complex i n d e t a i l and comprises s e v e r a l s m a l l e r mantos which are c l o s e l y stacked v e r t i c a l l y (Figure 8). In c r o s s s e c t i o n the s m a l l mantos merge a t t h e i r c e n t e r s but are d i s t i n g u i s h a b l e at t h e i r margins (Plate XV.a). The s m a l l mantos, i n g e n e r a l , have a t u b u l a r shape w i t h a f l a t t e n e d e l l i p t i c a l c r o s s s e c t i o n . The l a t e r a l margins of the manto do not form a pinch-out but comprise rounded t e r m i n a t i o n s with an abrupt c o n t a c t between s u l p h i d e or s p a r r y dolomite and S o c i e t y C l i f f s Formation dolomite. Rounded t e r m i n a t i o n s of manto margins are w e l l exposed i n the e a s t e r n underground development a t N a n i s i v i k main ore zone ( P l a t e XV.b). S i m i l a r t e r m i n a t i o n s e x i s t a t Hawker Creek (Figure 7; P l a t e XIV.b). 88 The e l e v a t i o n s o f the s m a l l mantos were compiled from diamond d r i l l c r o s s s e c t i o n s (Watts, G r i f f i s and McOuat, 1973) by measuring the e l e v a t i o n of the top or p r o j e c t e d top of each manto (Table V I I I ) . These data show t h a t the i n d i v i d u a l mantos e x i s t a t s p e c i f i c e l e v a t i o n s , p l u s o r minus a few f e e t , f o r thousands o f f e e t along t h e i r l e n g t h . The commonest e l e v a t i o n s are, approximately, 1040 f e e t , 1032 f e e t , 1010 f e e t and 1000 f e e t . Small s u l p h i d e mantos a l s o e x i s t at other e l e v a t i o n s but i n s u f f i c i e n t diamond d r i l l i n g has been done to a c c u r a t e l y -d e l i n e a t e them. Table V I I I i n d i c a t e s t h a t the s m a l l mantos which e x i s t a t the h i g h e r e l e v a t i o n s a t the e a s t e r n end o f N a n i s i v i k main ore zone app a r e n t l y d i e out r a t h e r a b r u p t l y to the west. The e l e v a t i o n s of other s u l p h i d e d e p o s i t s a t N a n i s i v i k are not a c c u r a t e l y known but the data a v a i l a b l e (Figure 4) i n d i c a t e t h a t they occur g e n e r a l l y w i t h i n s p e c i f i c e l e v a t i o n ranges. However, c o r r e l a t i o n of N a n i s i v i k main ore zone e l e v a t i o n w i t h e l e v a t i o n s o f o t h e r d e p o s i t s i s d i f f i c u l t because N a n i s i v i k area i s complexly b l o c k f a u l t e d and there are, as y e t , no e a s i l y a v a i l a b l e or p r e c i s e s t r a t i g r a p h i c markers. V o l u m e t r i c changes along the l e n g t h of N a n i s i v i k main ore zone composite manto can be estimated from v a r i a t i o n s i n c r o s s s e c t i o n a l area of the manto (Table V I I I ) . Cross s e c t i o n a l area of the manto was measured on each diamond d r i l l s e c t i o n (Watts, G r i f f i s and McOuat, 1973) u t i l i z i n g a p l a n i -meter. The r e s u l t s are summarized i n Table IX. Cross 89 PLATE XV. a Termination of a small manto e x i s t i n g at 1,700 South Cross-cut, Nanisivik main ore zone. Note the lack of sym-metry i n the sulphide and sparry dolomite deposited at the upper and lower contacts of the manto. Also note the trun-cation of the northerly dipping (to the right) Society C l i f f s Formation dolomite by the h o r i z o n t a l manto. A hammer ex i s t s for scale i n the upper portion of the plate. PLATE XV.b 'Rounded' termination of the small manto e x i s t i n g at 1,700 North Cross-cut, Nanisivik main ore zone. This i s the northern termination of the small manto i l l u s t r a t e d i n Plate XV.a. This i s also one of the few l o c a l e s where there i s an i n d i c a t i o n that sulphide and sparry dolomite may have deposited simultaneously on the roof, wall and f l o o r of the old c a v i t y . However, sixty feet to the south, within the same cross-cut (i.e. at the location of Plate VIII.b), there i s no i n d i c a t i o n of simultaneous deposition on the roof and f l o o r ( i.e. there i s no symmetry to the mineral deposit and a vuggy or open central core does not e x i s t ) . 9 0 TABLE VIII MANTO ELEVATIONS AND CROSS SECTIONAL AREA NANISIVIK MAIN ORE ZONE Diamond D r i l l Section Manto (in Elevations feet) Cross Sectional Area (in sq. f t . ) 63,717E 1, 045 1,032 1,014 998 7,000 63,527E 1, 040 1,030 1,000 6,100 63,336E 1, 042 1,034 1,010 6,400 63,146E 1, 041 1,034 5,400 62,956E 1, 038 N.E. 1 5,700 62 ,766E 1, 041 N.E. 5 ,900 62,576E 1, 041 N.E. 8,500 62,385E 1, 039 1,035 6,400 62,195E 1,034 5,400 62,005E 1,031 1,012 4,300 61,814E 1,032 . 1,013 1,002 8,200 . . 61,624E 1,032 1,008 7,700 61,434E 1,030 1,008 1,002 6,200 61,058E 1,027 12,400 60,867E 1,023 11,800 60,667E 1,020 1,008 13,500 60,122E .1,014 1,002 13,000 59,981E 1,015 9,500 59,698E 1,005 5,6002 59,414E 995 " 11,700 59,271E 1,008 11,800 59,129E . 998 7 ,6002 : • 58,851E 1,008 1,002 10,800 58,639E ; • 998 •11,800 58,000E 1,005 8 ,200 57,600E 1,007 1,000 - 12,600 57,200E 1,011 N.E. 3 57,000E 1,006 6,6002 56,800E 1,012 12,000 56,600E 1,010 1,004 16,400 56,400E 1,010 12,200 56,200E 1,020 1,008 15,000 56,000E 1,010 15 ,200 55,800E 1,015 1,000 21,300 55,600E 1,013 1,000 27,800 4 55,400E 1,010 31,2004 55,200E 1,010 21,400 55,000E 1,010 995 13 ,0005 """Not estimated because the elevation of a di s c r e t e manto could not be d i f f e r e n t i a t e d . This could a r i s e because the manto e x i s t i n g at t h i s elevation was so completely merged with the overlying manto that i t s margins are now destroyed. Alternatively, i n s u f f i c i e n t diamond d r i l l i n g may have been done to delineate the lower manto. 2 I n s u f f i c i e n t diamond d r i l l i n g has been done on t h i s section to accurately delineate the manto. Hence the value tabulated may have a large e r r o r associated with i t . 3Not estimated because the manto abuts the diabase dyke in t h i s section and therefore a continuous cross section i s not present. 4 The shape of the manto i s complicated by the e x i s -tence of f a u l t i n g and/or a d d i t i o n a l mantos. The values given are probably too large. ~*A portion of the manto i s eroded i n t h i s section. 91 TABLE IX SUMMARY - CROSS SECTIONAL AREA NANISIVIK MAIN ORE ZONE Approximate Cross s e c t i o n a l Area Diamond D r i l l S e c t i o n Length ( i n .square f e e t ) From To ( i n f e e t ) Average Range  63,717E 61,434E 2,700 =6,400 4,300 to 8,500 61,058E 56,800E 4,800 =10,500 5,600 to 13,500 56,600E 55,000E 1,600 =20,000 12,200 to 31,200 s e c t i o n a l area data are very approximate but do show t h a t the volume o f the manto i n c r e a s e s markedly i n the v i c i n i t y o f diamond d r i l l s e c t i o n s 61,058E and 56,600E (Figure 8). A geo-p h y s i c a l anomaly extends e a s t e r l y from the v i c i n i t y o f diamond d r i l l s e c t i o n 56,600E and may i n d i c a t e a s u l p h i d e body j o i n s the main ore zone at t h i s l o c a l e (Figure 4 ) . Evidence f o r a s u l p h i d e body j o i n i n g the main ore zone i n the v i c i n i t y o f diamond d r i l l s e c t i o n 61,058E i s l e s s c o n c l u s i v e . However, a s u l p h i d e body was i n t e r s e c t e d i n diamond d r i l l holes approximately 1,2 50 f e e t n o r t h e a s t e r l y of 61,058E, 52,500N and C l a y t o n (1962) suggested t h i s s u l p h i d e body trends southwesterly and j o i n s the main ore zone. More rec e n t g e o p h y s i c a l surveys, however, i n d i c a t e t h i s s u l p h i d e body may tr e n d e a s t e r l y (Figure 4). The k e e l which u n d e r l i e s the manto p o r t i o n of N a n i s i v i k main ore zone i s w e l l exposed o n l y i n the canyon w a l l a t Twin Lakes Creek. At t h i s l o c a l e i t i s a v e r t i c a l body wi t h an i r r e g u l a r c o n f i g u r a t i o n and comprises mainly h o r i z o n t a l l y banded p y r i t e w i t h some s p a r r y d o l o m i t e . N ear t h e t o p o f t h e c a n y o n w a l l a f l a t - l y i n g p y r i t e zone e x t e n d s o u t w a r d f r o m t h e k e e l and forms a manto. E l s e w h e r e a t N a n i s i v i k main o r e zone t h e k e e l i s n o t w e l l d e l i n e a t e d b e c a u s e diamond d r i l l h o l e s were n o t u s u a l l y c o n t i n u e d b e l o w t h e b a s e o f t h e l a r g e , c o m p o s i t e manto. The few diamond d r i l l h o l e s t h a t do i n t e r s e c t t h e k e e l i n d i c a t e t h a t a t some l o c a l e s i t e x t e n d s a t l e a s t 24 0 f e e t b e l o w t h e c o m p o s i t e manto, i t s w i d t h r a n g e s f r o m l e s s t h a n 10 f e e t t o o v e r 60 f e e t , and i t has an i r r e g u l a r c o n f i g u r a t i o n b u t e x i s t s most commonly e i t h e r as a s o u t h e a s t e r l y p o i n t i n g , o v e r t u r n e d v - s h a p e d ( i . e . 1 <•1 ) body o r as a s u b - v e r t i c a l body ( F i g u r e 8 ) . Ore m i n e r a l and gangue r a t i o s a r e m a r k e d l y v a r i a b l e a t a l l s c a l e s w i t h i n N a n i s i v i k main o r e zone. M i c r o s c o p i c and m e s o s c o p i c v a r i a t i o n s have been summarized p r e v i o u s l y and a r e n o t c o n s i d e r e d h e r e . A t t h e m e g a s c o p i c s c a l e a few g e n e r a l t r e n d s e x i s t . The most e c o n o m i c a l l y i m p o r t a n t t r e n d s a r e t h e i n c r e a s e i n o v e r a l l g r a d e and t h e i n c r e a s e i n z i n c t o l e a d a t o m i c r a t i o f r o m e a s t t o w e s t w i t h i n N a n i s i v i k m a i n o r e zone ( T a b l e X ) . W i t h i n t h e manto p o r t i o n o f N a n i s i v i k main o r e zone t h e h i g h e s t g r a d e z i n c - l e a d z o n e s e x i s t commonly n e a r t h e b o t t o m and m a r g i n s o f t h e manto, whereas t h e m i d d l e and u p p e r p o r t i o n s o f t h e manto, and a l s o a p p a r e n t l y t h e k e e l , a r e p r e d o m i n a n t l y p y r i t e and m a r c a s i t e w i t h o r w i t h o u t s p a r r y d o l o m i t e , s p h a l e r i t e and g a l e n a (Watts, G r i f f i s and McOuat, 19 7 3 ) . I f N a n i s i v i k m a i n o r e zone c o n t i n u e s t o t h e e a s t , i n t o t h e d e p o s i t s e x i s t i n g n o r t h w e s t o f K u h u l u L a k e , and t o the south, i n t o Twin Lakes p y r i t e zone, then i r o n s u l p h i d e i s the predominant s u l p h i d e a t both ends o f t h i s l a r g e d e p o s i t . TABLE X  ORE METAL VARIATIONS 1  NANISIVIK MAIN ORE ZONE Zinc Lead Zinc : Lead L o c a t i o n ( i n %) ( i n %) atomic r a t i o E a s t Zone 11.03 1.70. 20.6 : 1 ' C e n t r a l Zone 15.34 1.3 7 .35.5 : 1 West Zone 16.01 1.15 44.1 : 1 Hawker Creek Area T h i r t y massive p y r i t e and/or z i n c - l e a d s u l p h i d e o c cur-rences, and s e v e r a l l e s s important o c c u r r e n c e s , i n c l u d i n g g e o t h i t e gossans, s u l p h i d e fragments i n dolomite and f r a c t u r e -f i l l s u l p h i d e s , are p r e s e n t a t Hawker Creek area (Figure 5). Massive s u l p h i d e crops out a t s e v e r a l p l a c e s along the n o r t h e r n and southern s i d e s of Hawker Creek. G e o p h y s i c a l surveys i n d i c a t e these s u l p h i d e outcrops are s u r f a c e e x p r e s s i o n s of s e v e r a l continuous s u l p h i d e d e p o s i t s (Appendix I I I ) . However, i n s u f f i c i -ent diamond d r i l l i n g has been done to t e s t the g e o p h y s i c a l anomalies and to d e l i n e a t e the s u l p h i d e d e p o s i t s . The most common trends o f the s u l p h i d e d e p o s i t s , as i n f e r r e d from the A f t e r 'Ore Reserve Summary' presented i n Watts, G r i f f i s and McOuat, 1973. 94 g e o p h y s i c a l surveys and from alignment of massive s u l p h i d e o u t c r o p s , are 145° and 160° to 165°; l e s s common trends are 073°, 090°, 115° to 120° and 180°. The megascopic shape of massive s u l p h i d e bodies a t Hawker Creek i s s p e c u l a t i v e . C a r t w r i g h t (i_n T r i g g , W o o l l e t t & A s s o c i a t e s L t d . , 1973, p. IV-11) suggested, on the b a s i s of an induced p o l a r i z a t i o n survey, t h a t a conductive body up t o 3,500 f e e t l o n g , by 4 00 f e e t wide, by up to 100 f e e t t h i c k , might e x i s t between occurrence SH2 8 and occurrence SH26 (Figure 5). The massive s u l p h i d e d e p o s i t s exposed i n trenches at occurrence SH25 (Figures 6 and 7) and a t occurrence ML2, are f l a t - l y i n g bodies with f l a t t e n e d e l l i p t i c a l c r o s s s e c t i o n s s i m i l a r t o the s m a l l mantos e x i s t i n g a t N a n i s i v i k main ore zone. T h e i r margins are rounded and the c o n t a c t between massive s u l -phide and S o c i e t y C l i f f s Formation i s g e n e r a l l y sharp (Plate X l V . b ) . The c o n f i g u r a t i o n of these d e p o s i t s i s somewhat i r r e g u l a r (e.g. i n F i g u r e 6) or comprises s m a l l , v e r t i c a l l y stacked mantos (Figure 7). In g e n e r a l , the l o c a l v a r i a t i o n s of s u l p h i d e and metal r a t i o s w i t h i n d e p o s i t s a t Hawker Creek are s i m i l a r t o those w i t h i n N a n i s i v i k main ore zone. At t r e n c h SH25-1 (Figure 6), average assays comprise 15.38 per cent z i n c , 1.58 per cent l e a d , 0.17 ounces per ton s i l v e r a n d v n e g l i g i b l e copper, and the z i n c to l e a d atomic r a t i o i s about 24:1. H o r i z o n t a l l y banded z i n c - r i c h u n i t s e x i s t toward the bottom and margins of the SH25-1 manto whereas s u l p h i d e r e l a t i o n s h i p s i n the upper and c e n t r a l p o r t i o n s of the manto are more complex 95 because bands and/or masses of s u l p h i d e are commonly i r r e g u l a r i n shape and terminate or grade out a b r u p t l y . Mesoscopic s t r u c t u r e s , i n c l u d i n g onlap, c r o s s - s t r a t i f i c a t i o n , c u t - a n d - f i l l and s u l p h i d e - s p a r r y dolomite b r e c c i a , e x i s t and complicate the g e n e r a l h o r i z o n t a l l y banded c h a r a c t e r o f t h i s manto. At t r e n c h SH25-2, massive s u l p h i d e c o n s i s t s predominantly of h o r i z o n t a l , i nterbanded p y r i t e and s p a r r y dolomite t h a t onlaps S o c i e t y C l i f f s Formation dolomite a t the margins of the manto (Figure 7; P l a t e X l V . b ) . The manto exposed at t r e n c h ML2 i s 4 5 f e e t wide by 3 f e e t t h i c k and c o n s i s t s almost e n t i r e l y of p y r i t e . C h r i s Creek and Other Areas At C h r i s Creek, r e c e n t stream e r o s i o n along the f a u l t which separates V i c t o r Bay Formation shale to the n o r t h from S o c i e t y C l i f f s Formation dolomite to the south has exposed a s m a l l massive p y r i t e d e p o s i t (Figure 3). The d e p o s i t trends e a s t e r l y , p a r a l l e l i n g the f a u l t , i s up to 4 f e e t wide by 8 f e e t h i g h by a t l e a s t 2,000 f e e t . l o n g , and e x i s t s e n t i r e l y w i t h i n S o c i e t y C l i f f s Formation dolomite ( P l a t e XVI) ..; The c r o s s s e c t i o n a l c e n t e r of the body g e n e r a l l y comprises h o r i z o n t a l l y banded p y r i t e , whereas the margins comprise e i t h e r h o r i z o n t a l l y banded s u l p h i d e or a 6 to 10 i n c h t h i c k b r e c c i a zone. B r e c c i a comprises c l a s t s of banded p y r i t e and p y r i t i z e d host dolomite cemented by p y r i t e . Loose, f i n e - c r y s t a l l i n e gypsum e x i s t s l o c a l l y a t the top of the body but i s probably o f secondary o r i g i n . S p h a l e r i t e and galena are not p r e s e n t although they e x i s t nearby as f i s s u r e - f i l l o c currences and as s m a l l masses w i t h i n S o c i e t y C l i f f s Formation dolomite. 96 PLATE XVI Cross sectional configuration of a massive p y r i t e body at Chris Creek. The plate i l l u s t r a t e s only the upper portion of the body. The diagram below the plate i l l u s t r a t e s the cross s e c t i o n a l configuration i n i t s entirety and the geological r e l a t i o n s h i p s present. 97 Massive s u l p h i d e d e p o s i t s a l s o e x i s t w i t h i n S o c i e t y C l i f f s Formation e a s t and south o f the C h r i s Creek p y r i t e body. Massive p y r i t e w i t h minor s p h a l e r i t e and galena crops out 2,500 e a s t e r l y o f C h r i s Creek d e p o s i t but the underground extent o f t h i s d e p o s i t i s unknown. S e v e r a l s m a l l outcrops o f massive p y r i t e e x i s t 3,150 f e e t s o u t h e r l y o f C h r i s Creek d e p o s i t a t occurrence GW3 (Figure 2). Geophysical surveys conducted a t t h i s l o c a l e i n d i c a t e a l a r g e s u l p h i d e d e p o s i t e x i s t s ( T r i g g , W o o l l e t t & A s s o c i a t e s L t d . , 1973). Hematite r e p l a c e s massive p y r i t e a t occurrence GW5, which i s 4,200 southwesterly o f occurrence GW3. Massive s u l p h i d e d e p o s i t s do e x i s t elsewhere a t no r t h B a f f i n I s l a n d but are r a r e and g e n e r a l l y s m a l l . At Su p r i s e Creek, s m a l l pods o f massive galena e x i s t l o c a l l y i n S o c i e t y C l i f f s Formation but are not eco n o m i c a l l y important ( T r i g g , Woollett, e t a l . , 1970). At the western end of K-mesa, p y r i t e and/or m a r c a s i t e r e p l a c e d o l o l u t i t e b r e c c i a which e x i s t s a t the base o f S o c i e t y C l i f f s Formation, form small outcrops o f p y r i t e - m a r c a s i t e sand, and e x i s t as c o n c r e t i o n s i n A r c t i c Bay Formation. At White Bay area, a f l a t - l y i n g massive s u l p h i d e body e x i s t s e n t i r e l y w i t h i n V i c t o r Bay. Formation limestone (Olson, 1970). The dimensions o f t h i s d e p o s i t , although d i f f i c u l t to a s c e r t a i n a c c u r a t e l y because i t outcrops on a c l i f f and was observed o n l y from a h e l i -c o p t e r , are estimated t o be 60 f e e t wide by 1 to 2 f e e t t h i c k . B o t r y o i d a l , r e n i f o r m and nodular marcasite w i t h minor s p h a l e r -i t e and galena e x i s t i n t a l u s below the d e p o s i t . 98 III.2 FISSURE-FILL OCCURRENCES F i s s u r e - f i l l occurrences comprise those occurrences where l e a d - z i n c - i r o n s u l p h i d e m i n e r a l s , w i t h o r without sparry-dolomite gangue, f i l l s mall 1 p a l e o f i s s u r e s 1 w i t h i n S o c i e t y C l i f f s Formation. P a l e o f i s s u r e s i n c l u d e f r a c t u r e s formed t e c t o n i c a l l y , and f r a c t u r e s and other s m a l l open spaces formed d u r i n g k a r s t i f i c a t i o n of S o c i e t y C l i f f s Formation. The k e e l which extends below N a n i s i v i k main ore zone c o u l d be co n s i d e r e d a f i s s u r e - f i l l d e p o s i t but i t i s excluded from the f i s s u r e -f i l l c l a s s because of i t s s i z e and i n t i m a t e r e l a t i o n s h i p with the l a r g e massive s u l p h i d e manto. In f i s s u r e - f i l l o c c urrences, s u l p h i d e and sp a r r y dolomite can l o c a l l y c o a t and/or cement b r e c c i a c l a s t s w i t h i n the host dolomite but they e x i s t most commonly as cement along f r a c t u r e s . Such cemented f r a c t u r e s are i r r e g u l a r , l o c a l l y anastomosing, s w e l l and/or p i n c h out r a p i d l y and are commonly up t o 1 i n c h wide by s e v e r a l yards l o n g . There are no p r e -f e r e n t i a l l y m i n e r a l i z e d d i r e c t i o n s because f i s s u r e - f i l l o ccurrences e x i s t p a r a l l e l to a l l major j o i n t o r f r a c t u r e t r e n d s . The c o n t a c t s between s u l p h i d e m i n e r a l s i n the f i s s u r e and S o c i e t y C l i f f s Formation dolomite are g e n e r a l l y sharp. At those l o c a l e s , however, where s u l p h i d e m i n e r a l s have r e p l a c e d the host dolomite, s u l p h i d e abundance i n the host dolomite i s g r e a t e s t at and near the f i s s u r e margin and r a p i d l y decreases away from the margin u n t i l s u l p h i d e s are e i t h e r absent a few inches away or e x i s t as r a r e , anhedral t o subhedral c r y s t a l s . Sulphide e x i s t s f a r t h e r from the c o n t a c t along carbonaceous l a y e r s i n r e g u l a r l y laminated a l g a l dolomite, i n d i c a t i n g such l a y e r s were p r e f e r e n t i a l l y f a v o u r a b l e f o r replacement. Mineralogy and F a b r i c S p h a l e r i t e and galena are the commonest s u l p h i d e m i n e r a l s i n f i s s u r e - f i l l o c c u r r e n c e s . P y r i t e and r e l i c t m a r c a s i t e e x i s t l o c a l l y . W u r t z i t e i s absent. White s p a r r y dolomite i s the commonest non-sulphide c o n s t i t u e n t . S p h a l e r i t e g e n e r a l l y e x i s t s as f i n e - to c o a r s e -g r a i n e d , anhedral t o subhedral c r y s t a l s which are o c c a s i o n a l l y l a m e l l a r growth twinned. S p h a l e r i t e e x i s t s i n the f i s s u r e , where i t e i t h e r coats f i s s u r e w a l l s or i s intergrown w i t h o t h e r f i s s u r e - f i l l m i n e r a l s , or i t r e p l a c e s the host dolomite and/or i t i s pseudomorphous a f t e r p y r i t e c r y s t a l s which e x i s t i n the host dolomite. S p h a l e r i t e never c o n t a i n s exsolved i r o n s u l p h i d e . S p h a l e r i t e i n a f i s s u r e i s g e n e r a l l y moderate y e l l o w i s h brown^ but c o l o r s range from 'honey-colored' to dark r e d d i s h brown and even, although r a r e l y , to l i g h t green. S p h a l e r i t e t h a t has r e p l a c e d host dolomite i s always a p a l e y e l l o w i s h brown whereas s p h a l e r i t e t h a t has r e p l a c e d p y r i t e i s moderate r e d d i s h brown. Galena e x i s t s as s m a l l , euhedral and s k e l e t a l cubes disseminated i n s p a r r y dolomite, as i r r e g u l a r masses intergrown C o l o r d e s c r i p t i o n s f o r s p h a l e r i t e conform to the Munsell c o l o r i d e n t i f i c a t i o n system (Goddard, e t a l . , 1963). 100 with s p h a l e r i t e , and as i r r e g u l a r masses i n host dolomite which i s adjacent t o the f i s s u r e . S p h a l e r i t e i s l o c a l l y pseudomorphous a f t e r galena but these minerals g e n e r a l l y e x i s t w i t h an i n t e r g r o w t h t e x t u r e . P y r i t e i s a common but minor c o n s t i t u e n t o f f i s s u r e -f i l l o c c u r r e n c e s . M a r c a s i t e was o r i g i n a l l y present a t many occurrences but i s now r a r e and i s commonly r e p l a c e d by pseudomorphous p y r i t e . P y r i t e g e n e r a l l y occurs as f i n e - g r a i n e d , euhedral c r y s t a l s which e i t h e r e x i s t i n and have r e p l a c e d the host dolomite or are intergrown w i t h o t h e r f i s s u r e - f i l l m i n e r a l s . P y r i t e has not r e p l a c e d s p h a l e r i t e but i s l o c a l l y r e p l a c e d by s p h a l e r i t e . White s p a r r y dolomite i s common wit h s u l p h i d e s i n f i s s u r e s and has l o c a l l y r e p l a c e d galena and s p h a l e r i t e c r y s t a l margins. Sparry dolomite e x i s t s t y p i c a l l y as f i n e -to c o a r s e - g r a i n e d , anhedral t o euhedral c r y s t a l s . At f i s s u r e margins, s p a r r y dolomite can e x i s t as euhedral, inward pro-j e c t i n g c r y s t a l s whereas w i t h i n the f i s s u r e i t g e n e r a l l y comprises anhedral, f i n e - g r a i n e d and intergrown c r y s t a l s which l o c a l l y have a vuggy t e x t u r e . In some p l a c e s s p a r r y dolomite f i l l e d f i s s u r e s c r o s s c u t and t r u n c a t e p y r i t i f e r o u s o r g a n i c l a y e r s i n host dolomite. These f e a t u r e s i n d i c a t e open-space f i l l i n g o f f i s s u r e s . Elsewhere, however, p y r i t i f e r o u s o r g a n i c l a y e r s can be t r a c e d r i g h t across s p a r r y dolomite f i l l e d f i s s u r e s by the u n i n t e r r u p t e d e x i s t e n c e o f p y r i t e c r y s t a l s . Furthermore, pyrobitumen i s common w i t h i n s p a r r y dolomite c r y s t a l s i n f i s s u r e s and i s g e n e r a l l y most abundant near the 101 f i s s u r e margins. These f e a t u r e s i n d i c a t e some spar r y dolomite f i l l e d f i s s u r e s were formed by a l t e r a t i o n or r e c r y s t a l l i z a t i o n o f the host dolomite along f r a c t u r e s . Pyrobitumen i s a common but q u a n t i t a t i v e l y minor gangue i n f i s s u r e - f i l l occurrences and g e n e r a l l y e x i s t s i n vo i d s between s p a r r y dolomite or s u l p h i d e c r y s t a l s . Other, r a r e r , gangue mi n e r a l s i n c l u d e g r a p h i t e , white b a r i t e , p u r p l e f l u o r i t e and q u a r t z . C a l c i t e does not e x i s t i n f i s s u r e f i l l o c c u r r e n c e s . G r a p h i t e i s c h a r a c t e r i z e d , under the ore micro-scope, by i t s lath-shaped c r y s t a l h a b i t , l i g h t grey t o l i g h t yellow-brown b i r e f l e c t a n c e and very s t r o n g a n i s o t r o p i s m . G r a p h i t e has been .recognized o n l y a t f i s s u r e - f i l l occurrence MC6. The or g a n i c m a t e r i a l a t a l l o t h e r s u l p h i d e occurrences and d e p o s i t s , i n c l u d i n g the massive z i n c - l e a d d e p o s i t s , i s an u n i d e n t i f i e d pyrobitumen. D i s t r i b u t i o n and S p a t i a l R e l a t i o n s h i p t o Massive  Zinc-Lead Deposits F i s s u r e - f i l l occurrences are most abundant w i t h i n the S o c i e t y C l i f f s Formation a t western Borden P e n i n s u l a . They do e x i s t elsewhere but are l e s s common. A reconnaissance i n v e s t i g a t i o n o f f i s s u r e - f i l l occurrence mineralogy i n d i c a t e s t h a t r e g i o n a l v a r i a t i o n s do not e x i s t . F i s s u r e - f i l l o ccurrences are u b i q u i t o u s a t Hawker Creek area. A c a r e f u l examination o f t h e i r s p a t i a l d i s t r i b u -t i o n and m i n e r a l o g i c a l v a r i a t i o n r e l a t i v e to known massive s u l p h i d e d e p o s i t s i n d i c a t e t h a t no systematic r e l a t i o n s h i p s e x i s t . 102 A t N a n i s i v i k a r e a , f i s s u r e - f i l l o c c u r r e n c e s a r e common b u t t h e r e h a s been no d e t a i l e d i n v e s t i g a t i o n o f t h e i r d i s t r i b u t i o n . F i s s u r e - f i l l o c c u r r e n c e s c r o s s - c u t N a n i s i v i k main o r e zone l o c a l l y ( P l a t e X.b) b u t a r e g e n e r a l l y uncommon. Diamond d r i l l h o l e l o g s , w h i c h were p r o v i d e d by N a n i s i v i k M i n e s L t d . , i n d i c a t e t h a t (1) p y r i t e - s p h a l e r i t e - s p a r r y d o l o m i t e f i s s u r e - f i l l o c c u r r e n c e s e x i s t on a l l s i d e s o f N a n i s i v i k main o r e z o n e , (2) t h e abundance o f f i s s u r e - f i l l o c c u r r e n c e s i s a p p r o x i m a t e l y t h e same b o t h above an d b e l o w t h e m a i n o r e z o n e , and (3) t h e abundance o f f i s s u r e - f i l l o c c u r r e n c e s does n o t , i n g e n e r a l , i n c r e a s e m a r k e d l y i n t h e i m m e d i a t e v i c i n i t y o f t h e main o r e z one. L o c a l l y , however, f i s s u r e - f i l l o c c u r r e n c e s do i n c r e a s e n e a r t h e m a i n o r e zone. F o r example, a t t h e e a s t e r n e n d o f N a n i s i v i k m a i n o r e zone i m m e d i a t e l y above t h e e a s t p o r t a l , f i s s u r e - f i l l o c c u r r e n c e s i n S o c i e t y C l i f f s F o r m a t i o n a r e common a d j a c e n t t o t h e m a s s i v e s u l p h i d e d e p o s i t b u t r a p i d l y d e c r e a s e i n abundance upwards, i . e . away f r o m t h e m a s s i v e s u l p h i d e zone. F u r t h e r m o r e , t h e s u l p h i d e ( m a i n l y p y r i t e ) t o s p a r r y d o l o m i t e r a t i o w i t h i n t h e s e f i s s u r e - f i l l o c c u r r e n c e s a l s o d e c r e a s e s r a p i d l y away f r o m t h e m a s s i v e s u l p h i d e z o n e . I I I . 3 DISSEMINATED SULPHIDE OCCURRENCES D i s s e m i n a t e d s u l p h i d e o c c u r r e n c e s c o m p r i s e t h o s e o c c u r r e n c e s where d i s c r e t e , d i s s e m i n a t e d s u l p h i d e c r y s t a l s o r s m a l l s u l p h i d e masses e x i s t i n a h o s t r o c k , w h i c h i s g e n e r a l l y a d o l o m i t e , and i n c l u d e s t h o s e o c c u r r e n c e s w h i c h c o n s i s t o f 103 p y r i t e c o n c r e t i o n s i n s h a l e . Not i n c l u d e d are the d i s s e m i n -ated s u l p h i d e s s p a t i a l l y a s s o c i a t e d w i t h massive s u l p h i d e d e p o s i t s or w i t h f i s s u r e - f i l l o c currences. The d i s t i n c t i o n i s somewhat a r b i t r a r y . Disseminated s u l p h i d e occurrences are common west of Milne I n l e t , most n o t a b l y a t K-Mesa, S u r p r i s e Creek, Quiet R i v e r , Magda West, Magda E a s t and BWCD areas (Figure 2 J , . b u t are much l e s s abundant e a s t of Milne I n l e t . S t r a t i g r a p h i c a l l y , d i sseminated s u l p h i d e s are most abundant at and near the c o n t a c t between A r c t i c Bay Formation and S o c i e t y C l i f f s Formation. West of Milne I n l e t t h i s c o n t a c t i s u b i q u i t o u s l y m i n e r a l i z e d with anomalous c o n c e n t r a t i o n s of galena and s p h a l e r i t e . D i r e c t and i n d i r e c t evidence e x i s t s f o r t h i s , i n c l u d i n g : (1) numerous occurrences of galena and s p h a l e r i t e were d i s c o v e r e d i n dolomite along the c o n t a c t ( T r i g g , W o o l l e t t , e t a l . , 1970; T r i g g , W o o l l e t t & A s s o c i a t e s , 1973), (2) creeks d r a i n i n g the c o n t a c t commonly c o n t a i n anomalous c o n c e n t r a t i o n s o f z i n c and l e a d i n stream sediment c o l l e c t e d j u s t below the c o n t a c t (Olson and Armstrong, 1970), and (3) a geochemical rock survey conducted a c r o s s the c o n t a c t a t three w i d e l y separate l o c a l e s showed t h a t the h i g h e s t c o n c e n t r a t i o n of z i n c and l e a d e x i s t a t o r immediately adjacent to .the c o n t a c t (Graf, 1974). Galena and s p h a l e r i t e content i n dolomite e x i s t i n g along the c o n t a c t , ranges from t r a c e to a few volume per cent i n s e l e c t e d specimens. Masses or c r y s t a l s o f s p h a l e r i t e and/or galena e x i s t commonly i n a non-porous dolomite and g e n e r a l l y c r o s s - c u t a l g a l laminae. These f e a t u r e s i n d i c a t e the 104 s u l p h i d e s r e p l a c e d the host dolomite.. P y r i t e , which i s commonly p a r t i a l l y o r completely r e p l a c e d by pseudomorphous s p h a l e r i t e , i s p r e s e n t but i s not abundant as a disseminated s u l p h i d e i n dolomite. P y r i t e a l s o e x i s t s as c o n c r e t i o n a r y masses i n upper A r c t i c Bay Formation shale at the western end of K-mesa. These p y r i t e c o n c r e t i o n s are up to 3 inches t h i c k by 20 inches long and g e n e r a l l y p a r a l l e l bedding. Bedding does not bend markedly around the c o n c e n t r a t i o n s , hence the c o n c r e t i o n s are probably secondary and were formed by replacement of l i t h i f i e d sediment. P y r i t e c o n c r e t i o n s a l s o e x i s t i n lower V i c t o r Bay Formation s h a l e . A l l the p y r i t e c o n c r e t i o n s which e x i s t a t t h i s s t r a t i -g r a p h i c l e v e l are found a t western Borden P e n i n s u l a ; none e x i s t e a s t of Milne I n l e t . In g e n e r a l , p y r i t e c o n c r e t i o n s i n V i c t o r Bay Formation sha l e are s m a l l and are r a r e l y l a r g e r than 0.4 inches t h i c k by 2.0 inches long. Disseminated, red, earthy hematite e x i s t s i n S o c i e t y C l i f f s Formation dolomite at S u r p r i s e Creek and K-mesa. At S u r p r i s e Creek, hematite e x i s t s i n areas not m i n e r a l i z e d by z i n c , l e a d or copper s u l p h i d e s (Woollett, Armstrong and Ahuja, 1970). At K-mesa, S o c i e t y C l i f f s Formation i s hematite-s t a i n e d from red, e a r t h y hematite which i s disseminated i n the dolomite or coats f r a c t u r e s u r f a c e s . Some of the hematite i s pseudomorphous a f t e r p y r i t e . Disseminated c h a l c o c i t e and b o r n i t e e x i s t s p a t i a l l y near dis s e m i n a t e d s p h a l e r i t e - g a l e n a - p y r i t e occurrences a t both S u r p r i s e Creek and K-mesa. 105 III.4 IRON OXIDE AND IRON HYDROXIDE DEPOSITS IN SOCIETY  CLIFFS FORMATION Mineralogy, F a b r i c and S i z e of Deposits Iron oxide d e p o s i t s c o n s i s t mainly of hematite whereas i r o n hydroxide d e p o s i t s c o n s i s t mainly of g o e t h i t e . Hematite e x i s t s e i t h e r as massive hematite d e p o s i t s w i t h i n S o c i e t y C l i f f s Formation or as f i n e - t o c o a r s e - g r a i n e d f l o a t d e r i v e d from these massive d e p o s i t s . In the massive d e p o s i t s hematite i s s t e e l blue-grey w i t h a m e t a l l i c l u s t e r and l o c a l l y i t e x i s t s w i t h s m a l l amounts of q u a r t z . The f i n e -g r a i n e d hematite f l o a t forms b r i g h t red gossans. Some of the d e p o s i t s of massive hematite are q u i t e l a r g e . At occurrence R03 (Figure 2), f o r example, massive hematite i s up to 30 f e e t t h i c k (Plate XVII) and hematite f l o a t e x i s t s over a s t r i k e l e n g t h of a t l e a s t 1.5 m i l e s . T h i s hematite d e p o s i t appears to be stratabound because i t extends l a t e r a l l y a t a constant e l e v a t i o n w i t h i n and near the base of S o c i e t y C l i f f s Formation. Moderate y e l l o w i s h brown to moderate brown g o e t h i t e e x i s t s as i s o l a t e d f l o a t or as g o e t h i t e boulder t r a i n s . Such boulder t r a i n s are g e n e r a l l y a s s o c i a t e d w i t h e x t e n s i v e areas of y e l l o w i s h , l i m o n i t i c i r o n - s t a i n i n g . G o e t h i t e fragments up to 2 f e e t i n l e n g t h e x i s t and commonly are abundant l o c a l l y . G o e t h i t e occurs as r e n i f o r m , b o t r y o i d a l or s t a l a c t i t i c masses with a c o n c e n t r i c or r a d i a l l y f i b r o u s i n t e r n a l s t r u c t u r e , o r , l e s s commonly, as s m a l l , p r i s m a t i c c r y s t a l s . Some g o e t h i t e fragments are l a y e r e d . T h i s l a y e r i n g i s s i m i l a r to t h a t p r e s e n t 106 i n massive p y r i t e d e p o s i t s and some g o e t h i t e fragments do c o n t a i n p y r i t e p a r t i a l l y r e p l a c e d by g o e t h i t e . D i s t r i b u t i o n and S p a t i a l R e l a t i o n s h i p to Massive  Zinc-Lead Deposits Hematite d e p o s i t s and g o e t h i t e occurrences e x i s t most abundantly a t western Borden P e n i n s u l a , p a r t i c u l a r l y west of BWCD area. There i s , however, a gene r a l s p a t i a l s e p a r a t i o n of g o e t h i t e and hematite; g o e t h i t e occurrences e x i s t mainly from BWCD area to C h r i s Creek area, whereas hematite d e p o s i t s e x i s t mainly from C h r i s Creek area t o N a n i s i v i k area (Figure 3). Nonetheless, hematite d e p o s i t s and g o e t h i t e occurrences both e x h i b i t the same s p a t i a l r e l a t i o n s h i p t o massive z i n c - l e a d d e p o s i t s . That i s , they g e n e r a l l y e x i s t s p a t i a l l y near, but always s o u t h e r l y of the massive d e p o s i t s (Figure 2). Examples of t h i s i n c l u d e occurrence R04, occurrence MC5 and hematite d e p o s i t s a t N a n i s i v i k . A t occurrence R04, fragments o f g o e t h i t e up to 2 f e e t i n l e n g t h e x i s t as f l o a t over an area tens o f yards i n diameter and the occurrence i s on s t r i k e with massive p y r i t e d e p o s i t s which e x i s t to the northwest along Hawker Creek. At occurrence MC5, massive hematite e x i s t s about 6,500 f e e t south o f the massive p y r i t e occurrence GW3, and about 2,300 f e e t south of occurrence GW5, at which hematite r e p l a c e s p y r i t e . A t N a n i s i v i k , massive hematite d e p o s i t s e x i s t south o f , and appa r e n t l y on s t r i k e with, the Twin Lakes p y r i t e zone (Figure 4). Society Cliffs Formation /Massive •; hematite... o/0 9ic 0/ •So Arctic Bay Formation Oct PLATE XVII Massive hematite i n S o c i e t y C l i f f s Forma-t i o n a t occurrence R03. The h e i g h t of the massive hematite outcrop i s a p p r o x i m a t e l y t h i r t y f e e t . The diagram below the p l a t e i l l u s t r a t e s the g e o l o g i c a l r e l a t i o n s h i p s p r e s e n t . The o b j e c t i n the lower r i g h t i s a h e l i c o p t e r door frame. 108 I I I . 5 DISCUSSION K a r s t i f i c a t i o n o f S o c i e t y C l i f f s Formation K a r s t terminology and important f a c t o r s a f f e c t i n g d e v e l o p i n g o f h o l o k a r s t , p a r t i c u l a r l y those f a c t o r s a f f e c t i n g development of l a r g e , i n t e g r a t e d cave systems, are summarized i n Appendix I I f o r those readers u n f a m i l i a r w i t h k a r s t p r o c e s s e s . There were a t l e a s t s i x episodes of k a r s t development, from Hadrynian to Recent, a t North B a f f i n I s l a n d (Table X I ) . Only f o u r of these k a r s t episodes (numbered I, I I , I I I and IV, from e a r l i e s t to most recent) a f f e c t e d S o c i e t y C l i f f s Formation. K a r s t Episode I - Formation of B r e c c i a and C o l l a p s e  S t r u c t u r e s The b r e c c i a t h a t e x i s t s u b i q u i t o u s l y w i t h i n S o c i e t y C l i f f s Formation a t western Borden P e n i n s u l a , was probably formed by an e v a p o r i t e s o l u t i o n - c o l l a p s e mechanism. There are s e v e r a l l i n e s of evidence t h a t support t h i s c o n c l u s i o n . (1) F i r s t , e v a p o r i t i c c o n d i t i o n s probably e x i s t e d d u r i n g most o r a l l of S o c i e t y C l i f f s Formation time. Although e v a p o r i t e s do not now e x i s t w i t h i n S o c i e t y C l i f f s Formation a t western Borden P e n i n s u l a , the sedimentary f a c i e s p r e s e n t , i . e . f i n e - g r a i n e d dolomite, laminated dolomite, f i n e l y m i c r o - g r a i n e d dolomite and dolomite b r e c c i a , i s t y p i c a l of those a s s o c i a t e d w i t h e v a p o r i t i c sequences (Leighton and Pendexter, 1962). F u r t h e r -more, the presence o f c h e r t nodules w i t h i n S o c i e t y C l i f f s Formation a l s o i n d i c a t e s e v a p o r i t e s were present as such c h e r t nodules (which are g e n e r a l l y o p t i c a l l y length-slow) commonly 109 form from r e s i s t a n t , r e s i d u a l s i l i c a l e f t a f t e r e v a p o r i t i c m i n e r a l s have been removed by s o l u t i o n (Folk and Pittman, 1971). (2) Second, b r e c c i a w i t h i n S o c i e t y C l i f f s Formation do not resemble cave break-down b r e c c i a forming i n modern caves ( J . F. Quinlan, p e r s o n a l communication, 1974). Modern cave breakdown b r e c c i a g e n e r a l l y comprise l a r g e angular b l o c k s which are commonly up to s e v e r a l f e e t i n l e n g t h (Sweeting, 1973; Davies, 1951). The abundant f i n e - g r a i n e d c l a s t s , i . e . the ' t r a s h 1 , which e x i s t s i n the b r e c c i a matrix, are more t y p i c a l o f b r e c c i a formed by e v a p o r i t e s o l u t i o n - c o l l a p s e ( T a y l o r e t a l . , 1975; R. W. MacQueen, p e r s o n a l communication, 1975). (3) T h i r d , e v a p o r i t e s o l u t i o n - c o l l a p s e b r e c c i a are r e l a t i v e l y common phenomena (Leighton and Pendexter, 1962, p. 57; B l a t t , e t aJL. , 1972, p. 518). Phanerozoic examples e x i s t , f o r example, w i t h i n C a s t i l e Formation, West Texas and New Mexico (Anderson, e t al_. , 1972) , Arroyo Penasco Formation, New Mexico (Armstrong, 1967), Edwards Group, Texas ( F i s h e r and Rodda, 1967; Rose, 1972) Minnelusa Formation, South Dakota and Wyoming (Bowles and Braddock, 1963) , Cape C r a u f o r d Formation, n o r t h B a f f i n I s l a n d ( N o r r i s , 1963; T r e t t i n , 1969), P r a i r i e Formation, Saskatchewan (De M i l l e , e t a l . , 1964), Madison Group, Wyoming (Roberts, 1966; Sando, 1974), and elsewhere. A Precambrian example e x i s t s w i t h i n Mescal Lime-stone , A r i z o n a , which c o n t a i n s s o l u t i o n b r e c c i a produced by i n t e r s t r a t a l k a r s t i f i c a t i o n o f s a l t (Shride, 1967). (4) L a s t l y , i t i s d i f f i c u l t t o e x p l a i n the widespread occurrence of b r e c c i a w i t h i n r e g u l a r l y laminated a l g a l dolomite f a c i e s , 110 TABLE XI  KARST EPISODES NORTH BAFFIN ISLAND K a r s t Time o f E p i s o d e ^ D e v e l o p m e n t Remarks IV R e c e n t A modern, b a r e m e r o k a r s t . R e c e n t c o r r o s i o n has f o r m e d c h a n n e l s ( i . e . bogaz). on t h e p r e s e n t l y e x p o s e d s u r f a c e o f S o c i e t y C l i f f s F o r m a t i o n . P o s t - ' A b u r i e d , e v a p o r i t e s o l u t i o n - c o l l a p s e B r o d e u r G r o u p p a l e o k a r s t . C o r r o s i o n o f i n t e r -• . : s t r a t i f i e d e v a p o r i t e s w i t h i n Cape C r a u f o r d F o r m a t i o n p r o d u c e d s o l u t i o n b r e c c i a , f o l d s and domes. T h e r e was, however, a p p a r e n t l y no a f f e c t on S o c i e t y C l i f f s F o r m a t i o n . P o s t - S h i p Now a b u r i e d p a l e o k a r s t b u t o r i g i n a l l y P o i n t p r o b a b l y a b a r e m e r o k a r s t o r h o l o -F o r m a t i o n t o k a r s t . ' S o u t h w e s t e r l y t i l t i n g c a u s e d p r e - B r o d e u r s o l u t i o n - t h i n n i n g and f o r m a t i o n o f G r o u p b r e c c i a and s i n k h o l e f e a t u r e s w i t h i n S h i p P o i n t F o r m a t i o n . T h e r e was," h owever, a p p a r e n t l y no a f f e c t on S o c i e t y C l i f f s F o r m a t i o n . , I I I P o s t - d i a b a s e Now a b u r i e d p a l e o k a r s t b u t o r i g i n a l l y d y k e t o p r e - p r o b a b l y a b a r e m e r o k a r s t . N o r t h e r l y G a l l e r y t i l t i n g and b l o c k f a u l t i n g e x p o s e d F o r m a t i o n S o c i e t y C l i f f s F o r m a t i o n ' d u r i n g p r e -G a l l e r y F o r m a t i o n t i m e ; k a r s t i f i c a t i o n o f S o c i e t y C l i f f s F o r m a t i o n p r o b a b l y o c c u r r e d b u t a h o l o k a r s t a p p a r e n t l y d i d n o t d e v e l o p . I I P o s t - V i c t o r O r i g i n a l l y a c o v e r e d , i n t e r s t r a t a l Bay F o r m a t i o n h o l o k a r s t a t Hawker C r e e k - N a n i s i v i k * t o p r e - a r e a . T h i s i s t h e k a r s t e p i s o d e o f S t r a t h c o n a m a j o r e c o n o m i c i m p o r t a n c e a t B o r d e n Sound P e n i n s u l a . E v e n t s i n c l u d e d : w e s t e r n F o r m a t i o n B o r d e n P e n i n s u l a was f a u l t e d and up-l i f t e d , V i c t o r Bay F o r m a t i o n was l o c a l l y removed a n d / o r k a r s t e d , and an i n t e r s t r a t a l h o l o k a r s t , i n c l u d i n g an e x t e n s i v e i n t e g r a t e d c a v e s y s t e m , d e v e l o p e d w i t h i n S o c i e t y C l i f f s F o r m a t i o n d o l o m i t e . P o s t - S o c i e t y Now a b u r i e d ( a l t h o u g h o r i g i n a l l y C l i f f s b a r e ) , e v a p o r i t e s o l u t i o n - c o l l a p s e F o r m a t i o n t o d o l o m i t e p a l e o k a r s t . U p l i f t o f p r e - V i c t o r S o c i e t y C l i f f s F o r m a t i o n a t w e s t e r n Bay . B o r d e n P e n i n s u l a a l l o w e d c i r c u l a t i o n F o r m a t i o n o f m e t e o r i c w a t e r , c o r r o s i o n o f i n t e r -s t r a t i f i e d e v a p o r i t e s , and f o r m a t i o n o f e x t e n s i v e s u b - s u r f a c e s o l u t i o n -c o l l a p s e b r e c c i a and c o l l a p s e s t r u c -t u r e s w i t h c o n c o m i t a n t s u r f a c e k a r s t i f i c a t i o n and e r o s i o n . T h i s k a r s t e v e n t o c c u r r e d p r i o r t o t h e d e p o s i t i o n o f V i c t o r Bay F o r m a t i o n . T h a t i s , t h e k a r s t e p i s o d e s d u r i n g w h i c h s i g n i f i c a n t k a r s t i f i c a t i o n o f S o c i e t y C l i f f s F o r m a t i o n o c c u r r e d . I l l i t s g e n e r a l absence from o t h e r f a c i e s at western Borden P e n i n s u l a , the o r i g i n of conformable and unconformable ru b b l e b r e c c i a , and why b r e c c i a commonly grades i n t o u n b r e c c i a t e d dolomite upwards whereas b a s a l c o n t a c t s are u s u a l l y sharp, except by an e v a p o r i t e s o l u t i o n - c o l l a p s e mechanism. An e v a p o r i t e s o l u t i o n - c o l l a p s e o r i g i n f o r the b r e c c i a r e q u i r e s t h a t e v a p o r i t e u n i t s were o r i g i n a l l y i n terbedded w i t h r e g u l a r l y laminated a l g a l dolomite, a s u b t i d a l or deeper water f a c i e s , over an e x t e n s i v e area a t Borden P e n i n s u l a . The q u e s t i o n a r i s e s as to whether e v a p o r i t e s c o u l d have been d e p o s i t e d i n such a l a r g e b a s i n of r e l a t i v e l y deep water. The above evidence i n d i c a t e i t can and d i d happen. In g e n e r a l , although s u b t i d a l c o n d i t i o n s must have p r e v a i l e d over much of the Borden P e n i n s u l a p a l e o b a s i n , water depth probably d i d not exceed 60 f e e t as algae are uncommon below t h a t depth (Heckel, 1972). F a c i e s changes i n d i c a t e t h a t the b a s i n shallowed to the e a s t , south, west and northwest; paleowater depths a t n o r t h e r n B a f f i n I s l a n d are not known wit h s u r e t y but evapor-i t e s do e x i s t w i t h i n S o c i e t y C l i f f s Formation a t B y l o t I s l a n d (Jackson and Davidson, 1975). Furthermore, t h e r e i s no s t r a t i g r a p h i c evidence t o i n d i c a t e long-shore c u r r e n t s e x i s t e d or t h a t there was a major connection between the p a l e o b a s i n and the open sea; d o l o l u t i t e s interbedded with r e g u l a r l y laminated a l g a l dolomite were probably d e r i v e d from l o c a l s h oals d u r i n g storm a c t i v i t y . In s h o r t , i t seems reasonable to p o s t u l a t e t h a t a l a r g e , r e s t r i c t e d , p r o t e c t e d , marine e v a p o r i t e b a s i n , with water depth ranging g e n e r a l l y from about 112 30 f e e t , i . e . wave base, to about 60 f e e t , e x i s t e d a t c e n t r a l Borden P e n i n s u l a d u r i n g most o r a l l of S o c i e t y C l i f f s Forma-t i o n time. Analogous 'deep' water e v a p o r i t e b a s i n s do e x i s t elsewhere. An example i s C a s t i l e Formation, an e v a p o r i t e sequence at West Texas and New Mexico, which formed d u r i n g the Permian from a body o f b r i n e t h a t l a y below average wave base i n a r e s t r i c t e d b a s i n , 165 m i l e s long by 96 m i l e s wide (King, 1971; Dean, 1975). Hsu (1972) c i t e d o t h e r examples of a n c i e n t and modern deep water e v a p o r i t e s , and Schmalz (1969) has p r e -sented a g e n e t i c model f o r the d e p o s i t i o n of such deep water e v a p o r i t e s . E v a p o r i t e s were probably d e p o s i t e d u b i q u i t o u s l y throughout the b a s i n which e x i s t e d a t c e n t r a l Borden P e n i n s u l a , although the amount of e v a p o r i t e d e p o s i t e d a t any one time may have v a r i e d a c c o r d i n g to l o c a l c o n d i t i o n s . However, i n t o t a l , the e v a p o r i t e u n i t s may have comprised o n l y a few per cent o f the o r i g i n a l s t r a t i g r a p h i c s e c t i o n . T r e t t i n (1969), f o r example, b e l i e v e d t h a t e v a p o r i t e s comprised not more than 10 per cent of member A of Cape Cr a u f o r d Formation, y e t e x t e n s i v e b r e c c i a t i o n o c c u r r e d . Water i n the Borden P e n i n s u l a p a l e o -b a s i n must have been i n t e r m i t t e n t l y or c o n t i n u o u s l y r e p l e n i s h e d a t a r a t e t h a t was s u f f i c i e n t l y r a p i d to ensure t h a t evapora-t i o n d i d not reduce water depth to i n t e r t i d a l c o n d i t i o n s , y e t was s u f f i c i e n t l y slow to a l l o w e v a p o r i t e u n i t s to p e r i o d i c a l l y accumulate. The d e p o s i t i o n o f S o c i e t y C l i f f s Formation was f o l l o w e d by u p l i f t of western Borden P e n i n s u l a d u r i n g the 113 S o c i e t y C l i f f s F o r m a t i o n - V i c t o r Bay Formation h i a t a l i n t e r v a l . T h i s u p l i f t allowed the c i r c u l a t i o n of meteoric water through p o r t i o n s of the formation and, hence, the c o r r o s i o n of evapor-i t e u n i t s . The s o l u t i o n o f e v a p o r i t e s may have been p a r t i a l l y f a c i l i t a t e d by connate water d e r i v e d from the dewatering of A r c t i c Bay Formation s h a l e . I f t h i s l a t t e r mechanism was l o c a l l y important, e v a p o r i t e c o r r o s i o n and concomitant b r e c c i a -t i o n o f d o l o m i t e , may have begun before S o c i e t y C l i f f s Formation was completely l i t h i f i e d . The s o l u t i o n of e v a p o r i t e beds caused the o v e r l y i n g dolomite beds to c o l l a p s e , forming b r e c c i a as i l l u s t r a t e d i n F i g u r e 9A. Because the b r e c c i a w i t h i n S o c i e t y C l i f f s Formation does not resemble break-down b r e c c i a formed i n modern caves, cave formation and cave r o o f c o l l a p s e may have been r e l a t i v e l y unimportant d u r i n g the process o f e v a p o r i t e s o l u t i o n and dolomite c o l l a p s e b r e c c i a t i o n . Stanton (1966), f o r example, argued t h a t interbedded non-evaporite s t r a t a c o u l d g r a d u a l l y s u b s i d e , fragment, and e v e n t u a l l y form an e v a p o r i t e - f r e e b r e c c i a , without the n e c e s s i t y of cave development. E v a p o r i t e s o l u t i o n accompanied by the c o l l a p s e of o v e r l y i n g dolomite, p r o v i d e s a reasonable mechanism to e x p l a i n the formation of the v a r i o u s types of b r e c c i a , and the dome, b a s i n and f i s s u r e s t r u c t u r e s which e x i s t i n S o c i e t y C l i f f s Formation (Figure 9). The s o l u t i o n b r e c c i a t i o n model p r e -supposes three c o n d i t i o n s were f u l f i l l e d . These c o n d i t i o n s a r e : (1) c o r r o d i n g waters were p r e f e r e n t i a l l y channeled through a p o r t i o n o f the e v a p o r i t e u n i t , probably by a f r a c t u r e , LEAF 114 OMITTED IN PAGE NUMBERING. 115 (2) c o l l a p s e o f the o v e r l y i n g dolomite formed a b r e c c i a zone which occupied a volume l a r g e r than the o r i g i n a l volume of the u n b r e c c i a t e d dolomite, and (3) e v a p o r i t e away from the f r a c t u r e corroded s l o w l y such t h a t the o v e r l y i n g beds s l o w l y s e t t l e d , without b r e c c i a t i o n , onto the u n d e r l y i n g beds, producing a pseudo-bedding plane c o n t a c t . T h i s p r e f e r e n t i a l c o r r o s i o n along f r a c t u r e s , and p a r t i c u l a r l y along the predominant 320 degree s e t , p r o v i d e s an e x p l a n a t i o n f o r the p r e f e r r e d o r i e n t a t i o n of the long axes of dome and b a s i n s t r u c t u r e s which e x i s t a t Hawker Creek. That the above c o n d i t i o n s were f u l f i l l e d i s not improbable as s i m i l a r events have been documented elsewhere. P f e i f f e r and Hahn (1973, p. 214), f o r example, presented an i l l u s t r a t i o n showing p r e f e r e n t i a l s o l u t i o n o f Z e c h s t e i n s a l t s from the P e r m i a n - T r i a s s i c sequence i n Germany. Where f r a c -t u r e s e x i s t , b r e c c i a has formed, whereas i n areas t h a t are f r e e o f f r a c t u r e s , B untsandstein beds have s e t t l e d onto Rotliegendes beds w i t h a pseudo-bedding plane c o n t a c t . Rose (1972) documented a s i m i l a r s i t u a t i o n i n Edwards Group, Texas. Space between the l a r g e b r e c c i a fragments which formed i n S o c i e t y C l i f f s Formation, were subsequently i n f i l l e d by f i n e r g r a i n e d dolomite fragments and/or cemented by s p a r r y dolomite p r i o r t o the d e p o s i t i o n of the b a s a l V i c t o r Bay Formation s h a l e . During k a r s t i f i c a t i o n , meteoric water a l s o removed the e v a p o r i t e from the nodular a l g a l dolomite f a c i e s which e x i s t s a t Uluksan P e n i n s u l a but the a l g a l framework of t h i s f a c i e s a p p a r e n t l y d i d not f a c i l i t a t e c o l l a p s e because b r e c c i a d i d not form. Surface k a r s t i f i c a t i o n of S o c i e t y C l i f f s Formation produced a paleotopography of low to moderate r e l i e f . Large c o l l a p s e s t r u c t u r e s , such as s i n k h o l e s , d i d not develop, probably because e v a p o r i t e beds were i n s u f f i c i e n t l y t h i c k t o form l a r g e , upward-stoping c o l l a p s e s t r u c t u r e s s i m i l a r t o those developed over Middle Devonian P r a i r i e E v a p o r i t e s a l t d e p o s i t s ( C h r i s t i a n s e n , et. al_. , 1973) . At e a s t e r n Borden P e n i n s u l a , S o c i e t y C l i f f s Formation was o n l y l o c a l l y exposed. E a s t of Milne I n l e t the h i a t a l p e r i o d was s h o r t , o r meteoric water d i d not c i r c u l a t e to any depth w i t h i n S o c i e t y C l i f f s Formation, because t h i c k e v a p o r i t e u n i t s s t i l l e x i s t . K a r s t Episode I I - Formation of an I n t e g r a t e d Cave  System Do massive s u l p h i d e d e p o s i t s occupy paleocaves? A cave i s a " n a t u r a l l y formed, subterranean open area or chamber, or s e r i e s of chambers. The i m p l i c a t i o n of s i z e i s t h a t i t i s l a r g e enough f o r a human being to e n t e r . " (Gary, McAfee and Wolf, 1972). Note t h a t i n the d e f i n i t i o n a cave i s not an o b j e c t , i t i s a c t u a l l y an empty space. A massive s u l p h i d e d e p o s i t , however, i s an o b j e c t . T h e r e f o r e , e v a l u a t i o n of the q u e s t i o n , "do massive s u l p h i d e d e p o s i t s a t B a f f i n I s l a n d occupy paleocaves?", f i r s t r e q u i r e s an i m a g i n a t i v e removal of s u l p h i d e s and gangue, l e a v i n g an 'empty' c a v i t y . Two f u r t h e r q u e s t i o n s immediately a r i s e : "does the empty c a v i t y a c c u r a t e l y r e f l e c t the o r i g i n a l cave shape o r has the paleocave shape been d r a s t i c a l l y m o d i f i e d 117 by ore f l u i d s ? " , and, " i f the paleocave shape i s unmodi-f i e d , does i t resemble shapes e x h i b i t e d by modern caves?" The answer t o these q u e s t i o n s i s yes because: (1) the r e l a t i v e p a u c i t y o f s u l p h i d e replacement and host dolomite c o l l a p s e b r e c c i a a t the margins o f the s u l p h i d e d e p o s i t s , i n d i c a t e t h a t the presen t margins of the s u l p h i d e d e p o s i t s do, i n f a c t , reasonably r e f l e c t the o r i g i n a l cave shape, and (2) a comparison of N a n i s i v i k main ore zone c r o s s s e c t i o n s (Figure 8) and of other massive s u l p h i d e d e p o s i t s (Figures 6 and 7; P l a t e s XlV.b, XV.a, XV.b and XVI.a), to cr o s s s e c t i o n s o f modern caves (Figure 10), shows t h a t s t r i k i n g s i m i l a r i t i e s e x i s t . Note s p e c i f i c a l l y the s i m i l a r i t y o f c r o s s s e c t i o n 59,271E i n Figure.8 t o F i g u r e s 10A and 10B, of F i g u r e -6, to F i g u r e 7 1 0 E 2 , and of-F i g u r e 7 to F i g u r e s 10C and 10D. In s h o r t , the manto and k e e l c o n f i g u r a t i o n of N a n i s i v i k main ore zone (Figure 8) bears a s t r i k i n g resemblance to the two end member shapes, i . e . tubes and canyons, found i n modern cave systems (Appendix I I ) . In a d d i t i o n , the dimensions o f the N a n i s i v i k paleocave, p a r t i c u l a r l y i t s l e n g t h and he i g h t , are comparable to dimensions o f l a r g e , modern caves. For example: (1) a t Mammoth Cave, Kentucky, the l a r g e s t trunk cave passage i s more than 2.5 m i l e s l o n g and has a c r o s s s e c t i o n t h a t i s t y p i c a l l y 98 t o 164 f e e t wide and 246 f e e t high"*"; (2) B i g Room, at Carsbad Caverns, Quinlan, 1970, p. 245. 118 New Mexico, i s over 2500 f e e t long, from 50 to 300 f e e t wide, and has a h e i g h t extending up to 285 feet"*"; (3) e l l i p t i c a l passages of H o l l o c h Cave, S w i t z e r l a n d , are 2 s e v e r a l k i l o m e t e r s long . Sulphide d e p o s i t s i n caves, or paleocaves, are not uncommon. Examples e x i s t a t : Upper M i s s i s s i p p i 3 4 V a l l e y ; Burgin Mine, T m t i c Mining D i s t r i c t , Utah ; 5 Eureka Mining D i s t r i c t , Nevada ; Les Malmes, south-e a s t e r n France ; A r v i k d e p o s i t , Northwest T e r r i t o r i e s , "Sweeting, 1973, p. 159; Davis, 1930, p. 588. 2 B o g l i , A. (1965), as r e p o r t e d i n Sweeting, 1973, p. 142. 3 H e y l , 1968; Heyl, e t a l . f 1959; Mullens, 1964. Mullens (1964, p. 498) s t a t e d t h a t a t Herman Smith 2 mine the tops and s i d e s of a cave about 6 f e e t h i g h , 14 f e e t wide, and 400 f e e t l o n g , were l i n e d by a sheet of galena 6 t o 12 inches t h i c k , and t h a t a s o l u t i o n b r e c c i a cemented by s p h a l e r i t e , i r o n s u l p h i d e and sparse galena v e i n s , f i l l e d p a r t of the cave under the a r c h formed by the sheet of galena. 4 Shepard, e t a^L. , 1968; Davis, 1930. Shepard, e t a l . (1968, p. 956) s t a t e d t h a t l e a d , z i n c and s i l v e r s u l p h i d e s p l u s gangue r e p l a c e carbonate rubble and b r e c c i a which e x i s t e d i n "pre-mineral caverns of c o n s i d e r a b l e s i z e . " 5 N o l a n and Hunt (1968, p. 982 and F i g . 6, p. 983) s t a t e d t h a t o x i d i z e d and u n o x i d i z e d z i n c and l e a d s u l p h i d e s e x i s t e d w i t h i n ' s i z e a b l e caves' developed i n dolomite. They hyp o t h e s i z e d t h a t caves developed by g r a v i t y s t o p i n g d u r i n g • o x i d a t i o n of s u l p h i d e d e p o s i t s . However, they a l s o s t a t e d t h a t i n some stopes " i t i s o f t e n i m p o s s i b l e to determine the top of the ore as mined and the bottom of the cave." g F o g l i e r i n i and Bernard, 1967; D.F. Sangster, G e o l o g i -c a l Survey of Canada, p e r s o n a l communication, 1975. F o g l i e r i n i and Bernard (1967) s t a t e d t h a t l e a d and z i n c s u l p h i d e f i l l e d paleocaves formed i n Cambrian and T r i a s s i c dolomite. 119 B No tea l * givan Cross section of Yorkshire bedding plone cave (after Sweeting, 1973.) No _col« given Meander trench (canyon) in bottom of small chamber, near Fotry Spring, Robertson Avenue, Mommoth Cove (after Bretz, 1942. ) TUBE AND CANYON CONFIGURATION IN MODERN CAVES Scote Smoll Tube Stole Boone Avenue CROSS SECTIONAL SHAPE OF SOME CAVE PASSAGES AT MAMMOTH CAVE (otter Deike, 1967) -ORMATION OF A GRADED CUT OFF (otter Deike, 1967) FIGURE 10: MODERN CAVE SHAPES 120 1 2 Canada ; D j e b e l H a l l o u f o r e body, T u n i s i a ; D e r b y s h i r e , . 3 4 G r e a t B r i t a i n ; E a s t T e n n e s s e e D i s t r i c t , U.S.A. ; P i n e 5 6 P o i n t , N o r t h w e s t T e r r i t o r i e s , Canada ; and e l s e w h e r e . """Sangster, 1971, p. 71; T. M u r a r o , E x p l o r a t i o n Manager, Cominco L t d . , p e r s o n a l c o m m u n i c a t i o n , 1973. M u raro s u g g e s t e d A r v i k d e p o s i t i s , a t l e a s t i n p a r t , a p a l e o c a v e i n w h i c h l e a d , z i n c and i r o n s u l p h i d e s were d e p o s i t e d . 2 R o u v i e r (1971) s t a t e d t h a t c a l c i t e , s p h a l e r i t e , g a l e n a , j o r d a n i t e and p y r i t e a r e f o u n d as e n c r u s t a t i o n s on t h e w a l l s , f l o o r and r o o f o f c a v e s w h i c h f o r m e d by s o l u t i o n i n g a l o n g j o i n t s i n l i m e s t o n e . 3 F o r d , 1969a and 1969b. F o r d (1969b) s t a t e d t h a t f l u o r i t e and b e d d e d g a l e n a - b a r i t e s a n d e x i s t as s e d i m e n t on c a v e f l o o r s . He a l s o s t a t e d t h a t t h e w a l l s , f l o o r and r o o f o f some c a v i t i e s a r e l i n e d by f l u o r i t e and s u l p h i d e s . 4 S k i n n e r (1971). Z i n c and i r o n s u l p h i d e s cement b r e c c i a w h i c h o c c u p i e s p a l e o c a v e s f o r m e d i n Lower O r d o v i c i a n d o l o m i t e and l i m e s t o n e . S i m i l a r d e p o s i t s a l s o e x i s t a t A u s t i n v i l l e - I v a n h o e D i s t r i c t , V i r g i n i a (Brown an d W e i n b e r g , 1968) and a t F r e i d e n s v i l l e , P e n n s y l v a n i a ( C a l l a h a n , 1 9 68). 5 S k a l l , H., 1975; B e a l e s and J a c k s o n , 1968. S k a l l (1975) s t a t e d t h a t d u r i n g m i d d l e t o l a t e G i v e t i a n h i a t u s , k a r s t i f i c a t i o n o c c u r r e d , p r o d u c i n g open c a v i t i e s and c o l l a p s e b r e c c i a t h a t l a t e r a c t e d as l o c i f o r l e a d and z i n c d e p o s i t i o n . The f o l l o w i n g a u t h o r s d i s c u s s e d t h e e x i s t e n c e o f s u l p h i d e m i n e r a l s i n c a v e s a n d / o r p a l e o c a v e s : W a l k e r (1 9 2 8 ) , D a v i s (1930), L i n d g r e n (1933), M a t h e r (1 9 4 7 ) , G r o g a n (1 9 4 9 ) , H i c k s ( 1 9 5 0 ) , K e n d a l l ( 1 9 6 0 ) , C a l l a h a n (1964, 1966 and 1968), M i l l s and E y r i c h ( 1 9 6 6 ) , G r u s z c z y k (1967), G a l k i e w i c z ( 1 9 6 7 ) , K o s t e l k a and P e t r a s c h e c k (1967) , Maucher and S c h n e i d e r (1967) , P e r e i r a ( 1 9 6 7 ) , S c h n e i d e r and Maucher (1967), T a u p i t z ( 1 9 6 7 ) , B r o c k i e , e t a l . ( 1 9 6 8 ) , G r o g a n and B r a d b u r y ( 1 9 6 8 ) , Radabaugh, e t a l . (1968), Tweto (1968a and 1968b), B o g a c z , e t a l . ( 1 9 7 0 ) , M o r r i s s e y and W h i t e h e a d (1970) , S m i t h and C o l l i n s (1971) , H a r a n c z y k ( 1 9 7 1 ) , C o l l i n s and S m i t h ( 1 9 7 2 ) , B r o u g h t o n (1972), Q u i n l a n ( 1 9 7 2 a ) , B e r n a r d (1973) and P a d a l i n o , e t a l . (1973). M o r r i s (1968) and M u l l e r (1972) d i s c u s s e d t h e e x i s t e n c e o f s u l p h i d e and o x i d e d e p o s i t s i n c a v e s ; t h e y b e l i e v e d , however, t h a t t h e c a v e f o r m e d by volume r e d u c t i o n d u r i n g s u l p h i d e o x i d a t i o n . H i c k s (1950) , Q u i n l a n (1972a) and B r o u g h t o n (1972) d i s c u s s e d t h e d e p o s i t i o n o f o t h e r m i n e r a l s , i . e . b e s i d e s s u l p h i d e s , i n c a v e s and p r o v i d e a f a i r l y e x t e n s i v e l i s t o f r e f e r e n c e s . 121 In summary, i t seems reasonable to conclude t h a t Borden P e n i n s u l a massive z i n c - l e a d d e p o s i t s do occupy an o l d cave system. Time o f cave development The e x i s t e n c e of massive z i n c - l e a d d e p o s i t s i n paleocaves r e q u i r e s t h a t a l a r g e i n t e g r a t e d cave system e x i s t e d p r i o r to s u l p h i d e d e p o s i t i o n . Important data t h a t bears on the time of cave development i n c l u d e : (1) S o c i e t y C l i f f s Formation e v a p o r i t e s o l u t i o n - c o l l a p s e b r e c c i a i s t r u n c a t e d by massive s u l p h i d e d e p o s i t s , (2) an e a s t e r l y t r e n d i n g f a u l t a t N a n i s i v i k area downdrops the c o n t a c t between S o c i e t y C l i f f s Formation and V i c t o r Bay Formation at l e a s t 4 00 f e e t , whereas N a n i s i v i k main ore zone c r o s s e s the f a u l t a t t h i s l o c a l e w i t h o n l y minor o f f s e t , (3) V i c t o r Bay Formation sha l e o v e r l y i n g the west end of N a n i s i v i k main ore zone i s m i n e r a l i z e d with p y r i t e , s p h a l e r i t e and galena, (4) N a n i s i v i k main ore zone i s probably c u t by a diabase dyke and t h i s dyke has given potassium-argon ages of 531 ±20-.myy. and -463.-±17 m.y. , (5) upper V i c t o r Bay Formation a t White Bay area was k a r s t e d p r i o r t o the d e p o s i t i o n of A t h o l e P o i n t Formation, (6) a t h i n , but l a t e r a l l y e x t e n s i v e , b l a c k s h a l e u n i t which occurs a t the base o f A t h o l e P o i n t Formation a t M i l n e I n l e t area i s t o t a l l y a t y p i c a l compared to other sediments comprising A t h o l e P o i n t Formation, (7) a t western B y l o t I s l a n d and a t E l w i n I n l e t area, a t h i c k , grey dolomite, which probably i s S o c i e t y C l i f f s Formation, 122 u n d e r l i e s Strathcona Sound Formation, (8) a c h a o t i c , p o o r l y s o r t e d , carbonate boulder conglomerate, red mudstone and red shale e x i s t w i t h i n lower Strathcona Sound Formation a t western Borden P e n i n s u l a , and (9) a s l i g h t but d i s t i n c t angular unconformity e x i s t s between sediments o f V i c t o r Bay Formation and of S t r a t h -cona Sound Formation n o r t h o f the head of Strathcona Sound. These data l i m i t cave development t o the time i n t e r v a l e x i s t i n g between the end of d e p o s i t i o n of V i c t o r Bay Formation and the i n t r u s i o n o f diabase. However, the development o f an e x t e n s i v e cave system r e q u i r e s S o c i e t y C l i f f s Formation to have been, a t l e a s t l o c a l l y , sub-a e r i a l l y exposed d u r i n g a h i a t a l p e r i o d . Two p o s s i b l e h i a t a l p e r i o d s e x i s t : the h i a t u s between V i c t o r Bay Formation and Strathcona Sound Formation, and the h i a t u s between E l w i n Formation and diabase i n t r u s i o n (Table I ) . The former h i a t u s i s probably the important one because i t b e s t e x p l a i n s the known data. A p o s t u l a t e d s c e n a r i o c o u l d comprise the f o l l o w -i n g events: (1) The f i r s t k a r s t i f i c a t i o n o f S o c i e t y C l i f f s Formation ( i . e . k a r s t episode I) ended when Borden P e n i n s u l a area was submerged. V i c t o r Bay Formation was de p o s i t e d , comprising, i n g e n e r a l , b l a c k s h a l e w i t h some carbonate at western Borden P e n i n s u l a and, to the e a s t , mainly limestone. 123 (2) F o l l o w i n g the d e p o s i t i o n of V i c t o r Bay Formation, western and northern Borden P e n i n s u l a were g r a d u a l l y u p l i f t e d , probably because o f c o n t i n u a l f a u l t a c t i v i t y , and b l a c k shale of V i c t o r Bay Formation was l o c a l l y eroded, p r o v i d i n g the sediment f o r the l a c u s t r i n e b l a c k shale which e x i s t s a t the base of A t h o l e P o i n t Formation. Continued u p l i f t along some f a u l t scarps e v e n t u a l l y l o c a l l y exposed S o c i e t y C l i f f s Formation dolomite and o l d e r r o c k s . E r o s i o n of these r o c k s , w i t h some c o n t r i b u t i o n of V i c t o r Bay Formation carbonate, p r o v i d e d the d e b r i s which formed the coarse, carbonate, f a n g l o m e r a t i c and f l u v i a l d e p o s i t s o f lower Strathcona Sound Formation. (3) C o n d i t i o n s f a v o u r a b l e f o r k a r s t i f i c a t i o n e x i s t e d , as evidenced, f o r example, by l o c a l k a r s t i f i c a t i o n o f V i c t o r Bay Formation limestone, and k a r s t i f i c a t i o n of S o c i e t y C l i f f s Formation dolomite began. E v e n t u a l l y , an e x t e n s i v e , i n t e g r a t e d cave system developed w i t h -i n S o c i e t y C l i f f s Formation. Cave development a t N a n i s i v i k and Hawker Creek areas was i n t e r s t r a t a l , i . e . caves formed beneath V i c t o r Bay Formation, whereas at western B y l o t I s l a n d and a t E l w i n I n l e t a rea, and p o s s i b l y elsewhere, a bare k a r s t developed on S o c i e t y C l i f f s Formation. T h i s bare k a r s t even-t u a l l y became a covered k a r s t as S o c i e t y C l i f f s Formation was p r o g r e s s i v e l y mantled by t e r r a r o s s a s o i l . (4) Borden P e n i n s u l a area again began to s i n k below sea l e v e l . T e r r a r o s s a s o i l was e r o d e d . l o c a l l y , forming the red s h a l e and red mudstone u n i t s of lower Strathcona Sound Formation. The s u r f a c e k a r s t l a n d -forms t h a t developed on S o c i e t y C l i f f s Formation were g e n e r a l l y not preserved."*" (5) Borden P e n i n s u l a e v e n t u a l l y became completely sub-merged and upper Strathcona Sound Formation, i n c l u d i n g A t h o l e P o i n t Formation, was d e p o s i t e d . The exact time of formation of the s u l p h i d e d e p o s i t s i s some-what s p e c u l a t i v e but i s o t o p i c evidence presented i n Chapter IV i n d i c a t e t h a t the s u l p h i d e s were not d e p o s i t e d from cave-forming waters, c o n t r a r y to the c o n c l u s i o n s o f G e l d s e t z e r (1970, 1973a). H y d r o l o g i c regimen d u r i n g cave development The h y d r o l o g i c regimen which e x i s t e d d u r i n g development of the paleocaves can be i n t e r p r e t e d from the c r o s s s e c t i o n a l shape, the v a r i a t i o n i n dimensions and the trends o f the massive z i n c - l e a d d e p o s i t s , and by analogy to h y d r o l o g i c regimens of modern cave systems (Appendix I D . Quinlan (1972a, p. 161) noted t h a t the amount o f r e l i e f on most u n c o n f o r m i t i e s exposed i n carbonate sequences i s l e s s than t h a t e x i s t i n g at most k a r s t t e r r a n e s . He p o s t u -l a t e d t h a t t h i s r e s u l t e d from the k a r s t s u r f a c e being planed by s u b a e r i a l or marine e r o s i o n d u r i n g or j u s t p r i o r to d e p o s i -t i o n o f the o v e r l y i n g beds. 125 In most modern caves, f r a c t u r e s are the major i n f l u e n c e on where a cave passage forms (Appendix I I ) . At Borden p e n i n s u l a , f r a c t u r e s appear to have been an important parameter d u r i n g cave formation because the s u l p h i d e d e p o s i t trends g e n e r a l l y c o r r e l a t e markedly w i t h e i t h e r the s t r i k e o f the major j o i n t s e t s ( i . e . 325°, 040° and 075°) o r w i t h the e a s t t r e n d i n g f a u l t s and oth e r f r a c t u r e s . However, ot h e r c o n t r o l s , f o r example the a t t i t u d e o f bedding, must h a v e . e x i s t e d a l s o , at l e a s t l o c a l l y , because the c o n f i g u r a t i o n o f some of the z i n c -l e a d d e p o s i t s i s not wholly e x p l a i n a b l e by j u s t a f r a c t u r e c o n t r o l . At N a n i s i v i k area, the massive s u l p h i d e d e p o s i t s t r e n d g e n e r a l l y east-west.and seem t o converge and enlar g e to the west. T h i s i n d i c a t e s t h a t k a r s t waters g e n e r a l l y flowed w e s t e r l y at N a n i s i v i k area. However, the abrupt change i n d i r e c t i o n o f N a n i s i v i k main ore zone, from w e s t e r l y t o s o u t h e r l y a t Twin Lakes Creek, i n d i c a t e s t h a t there was an abrupt change i n the l i n e - o f - l e a s t - f l o w -r e s i s t a n c e a t t h i s l o c a l e , which caused w e s t e r l y f l o w i n g k a r s t waters to tu r n and flow s o u t h e r l y . The exact reason f o r t h i s change i n flow d i r e c t i o n i s not apparent but may have been a s u b t l e s t r u c t u r a l c o n t r o l , i . e . a combination o f f r a c t u r e s and/or folds."'' The l o c a t i o n o f the d i s c h a r g e Sweeting (1973, p. 138 and 139), f o r example, noted the importance of s u b t l e t e c t o n i c i n f l u e n c e s on the development of cave passages. Deike (1967) noted t h a t some cave passages a t Mammoth cave are c o n t r o l l e d by f o l d t r e n d s . 126 area f o r the N a n i s i v i k paleocaves i s s p e c u l a t i v e but was presumably s o u t h e r l y or w e s t e r l y , towards Adams Sound. The recharge area of the N a n i s i v i k k a r s t waters a p p a r e n t l y l a y i n an e a s t e r l y d i r e c t i o n . At Hawker Creek area, the massive s u l p h i d e d e p o s i t s are not d e l i n e a t e d adequately. Hence, the i n t e r p r e t a t i o n of k a r s t water p a l e o f l o w d i r e c t i o n s i s h i g h l y s p e c u l a t i v e . Geophysical surveys i n d i c a t e t h a t most of the g e o p h y s i c a l anomalies t r e n d n o r t h w e s t e r l y -s o u t h e a s t e r l y and t h a t the l a r g e s t conductor, which has been i n t e r p r e t e d as due to a s u l p h i d e d e p o s i t , e x i s t s to the southeast, whereas s m a l l e r , more numerous conductors e x i s t t o the northwest. The r e f o r e , i t i s t e n t a t i v e l y concluded t h a t k a r s t waters flowed s o u t h e a s t e r l y a t Hawker Creek area and may have d i s c h a r g e d into: a. p a l e o -v e r s i o n o f Adams R i v e r v a l l e y . L i t t l e o r nothin g about the p a l e o f l o w d i r e c t i o n o f k a r s t water can be determined from the s u l p h i d e body at C h r i s Creek or from the massive hematite occurrence R03"^. I t i s i n t e r e s t i n g , however, t h a t p r o j e c t i o n s o f the t r e n d of these d e p o s i t s i n t e r s e c t a t N a n i s i v i k area. An e a s t e r l y p r o j e c t i o n of the N a n i s i v i k d e p o s i t s and a n o r t h w e s t e r l y p r o j e c t i o n o f the Hawker Creek I t w i l l be demonstrated t h a t massive hematite d e p o s i t s are probably d e r i v e d from s u l p h i d e d e p o s i t s . 127 anomalies, i n t e r s e c t near the head of Strathcona Sound a t approximately 73°7'7"N l a t i t u d e , 83°47'30"W l o n g i t u d e (Figure 2). I d e a l l y , t h i s i n t e r s e c t i o n should be the recharge area f o r p a l e o k a r s t waters. T h i s seems extremely u n l i k e l y however because S o c i e t y C l i f f s Formation i s capped by a t h i c k sequence of V i c t o r Bay Formation s h a l e at t h i s l o c a l e . T h i s impasse i s r e s o l v a b l e i f the o r i g i n a l d i s c h a r g e area was l o c a t e d a few m i l e s n o r t h e r l y . T h i s i s not unreasonable because S o c i e t y C l i f f s Formation may have been l o c a l l y exposed a t B a i l l a r g e R i v e r area and was almost c e r t a i n l y exposed a t E l w i n I n l e t area.during'the h i a t u s between the d e p o s i t i o n of V i c t o r Bay Formation and o f S t r a t h c o n a Sound Formation. Furthermore, t h i s s i t u a -t i o n , i . e . t h a t the i n t e r s e c t i o n of the g e n e r a l t r e n d o f s p a t i a l l y near but g e n e r a l l y separate cave systems i s not the recharge s i t e , i s not uncommon. In a modern s i t u a t i o n i n Kentucky, f o r example, the F l i n t Ridge Cave System g e n e r a l t r e n d i n t e r s e c t s the Mammoth Cave g e n e r a l t r e n d some 7 to 10 m i l e s from the a c t u a l recharge area a t Penny-r o y a l P l a i n . Regardless o f whether o r not E l w i n I n l e t area was the recharge s i t e f o r N a n i s i v i k and Hawker Creek cave-forming waters, the l a r g e area of S o c i e t y C l i f f s Formation t h a t was exposed e a s t o f E l w i n I n l e t d u r i n g the h i a t u s between V i c t o r Bay Formation and Strathcona Sound Formation i n d i c a t e s t h a t t h i s area must have had a p r o -found i n f l u e n c e on the k a r s t hydrology and was probably 128 e i t h e r a s i t e o f recharge or of d i s c h a r g e , or p o s s i b l y , of both. The c l o s e l y stacked, m u l t i p l e manto c o n f i g u r a -t i o n a t N a n i s i v i k main ore zone and the l a r g e dimensions of the main ore zone i n d i c a t e t h a t t h e r e was a* 1 l e n g t h y 1 p e r i o d o f base l e v e l s t a b i l i z a t i o n d u r i n g which t h e r e were o n l y minor f l u c t u a t i o n s i n the e l e v a t i o n o f the p i e z o m e t r i c s u r f a c e . The exact l e n g t h o f t h i s s t a b i l i z a -t i o n p e r i o d i s not known but was probably s e v e r a l m i l l i o n years.''" The k e e l which e x i s t s below the manto i n d i c a t e s , however, t h a t the base l e v e l e v e n t u a l l y d e c l i n e d such t h a t a canyon was downcut. Small mantos e x i s t i n g a t other l e v e l s probably r e p r e s e n t tubes formed d u r i n g o t h e r , s h o r t e r p e r i o d s of base l e v e l s t a b i l i z a t i o n . The h o r i z o n t a l , e l l i p s o i d c r o s s s e c t i o n a l shape of the mantos i n d i c a t e s the tubes formed beneath a p i e z o m e t r i c s u r f a c e from c o r r o d i n g waters which were r a p i d l y f l o w i n g and f r e q u e n t l y mixed (Appendix I I ) . The absence of c l a y i n f i l l and breakdown b r e c c i a i n the s u l p h i d e d e p o s i t s i s not unusual and, i n f a c t , i s common where cave systems are o v e r l a i n by an impervious cap rock (Appendix I I ) . Mammoth Cave and F l i n t Ridge Cave System, a l a r g e modern cave system, probably the world's l a r g e s t (J. Quinlan, p e r s o n a l communication, 19 74) i s thought t o have formed over s e v e r a l m i l l i o n years beginning i n P l i o c e n e time (Quinlan, 1970). 129 K a r s t Episode I I I - Formation o f Hematite Deposits The s p e c i f i c processes by which hematite and g o e t h i t e form, and the exact s t a b i l i t y r e l a t i o n s h i p s between the two m i n e r a l s , are not known wit h s u r e t y . Berner (1969) concluded: (1) g e o t h i t e i s thermodynamically u n s t a b l e r e l a t i v e t o hematite p l u s water under p r a c t i c a l l y a l l g e o l o g i c a l c o n d i t i o n s , (2) the maximum temperature of s t a b i l i t y , i . e . m e t a s t a b i l i t y , of g o e t h i t e i s 40°C at 1 atmosphere, and (3) given s u f f i c i e n t time and/or b u r i a l , g o e t h i t e w i l l dehydrate to hematite. Langmuir (1971) s t a t e d t h a t : (1) c o a r s e - g r a i n e d g o e t h i t e ( i . e . g r e a t e r than 1 micron) i s s t a b l e r e l a t i v e t o c o a r s e - g r a i n e d hematite i n water up t o 80°C but once hematite has appeared i t does not rehydrate to form g o e t h i t e , and (2) hematite can form at depth as w e l l as a t the l a n d s u r f a c e whereas the occurrence of g o e t h i t e i n s o i l s or sediments w i l l u s u a l l y mean t h a t such m a t e r i a l s are r e c e n t and formed i n the presence of an aqueous phase. Brown (1971) s t a t e d t h a t thermodynamic c a l c u l a t i o n shows t h a t the s t a b i l i t y f i e l d s (Eh-pH) o f g o e t h i t e and hematite are approximately the same at 25°C and 1 atmosphere. 1 These data i n d i c a t e t h a t g o e t h i t e has formed at Borden P e n i n s u l a by the Recent o x i d a t i o n of p y r i t e , w i t h the pH b u f f e r e d a t n e a r - n e u t r a l a c i d i t y by carbonate. G o e t h i t e 1 s placement time-wise i s t h e r e f o r e more p r o p e r l y i n k a r s t episode Compare Brown's (1971, p. 2 47, F i g . l a ) Eh-pH diagram i l l u s t r a t i n g g o e t h i t e ' s s t a b i l i t y f i e l d to G a r r e l s and C h r i s t ' s (1965, p. 221, F i g . 7.19) Eh-pH diagram i l l u s t r a t i n g hematite's s t a b i l i t y f i e l d . 130 IV. Hematite, however, need not be of Recent o r i g i n because once i t i s formed, i t i s s t a b l e . Hematite c o u l d , t h e r e f o r e , have formed d u r i n g an e a r l i e r p e r i o d of s u l p h i d e d e p o s i t o x i d a t i o n . The most probable e a r l i e r time of hematite formation was d u r i n g the diabase i n t r u s i o n - G a l l e y Formation h i a t u s , i . e . d u r i n g K a r s t episode I I I , because.Society C l i f f s Formation was l o c a l l y exposed by block f a u l t i n g and n o r t h e r l y t i l t i n g . Exten-s i v e k a r s t i f i c a t i o n may or may not have o c c u r r e d but i t i s very probable t h a t a t l e a s t some s u l p h i d e d e p o s i t s were exposed t o o x i d i z i n g meteoric waters because G a l l e r y Formation i s a r e d -bed sequence and o u t l i e r s of G a l l e r y Formation are s p a t i a l l y near hematite d e p o s i t s and/or p y r i t e d e p o s i t s a t N a n i s i v i k , occurrence R03 and occurrence GW5 (Figures 2 and 3). A l t e r n a -t i v e l y , t here i s a p o s s i b i l i t y , a l b e i t remote, t h a t hematite may not even be o f secondary o r i g i n but was d e p o s i t e d as a primary m i n e r a l d u r i n g f o r m a t i o n o f the massive s u l p h i d e deposits."'' T h i s p o s s i b i l i t y i s c o n s i d e r e d u n l i k e l y , however, because hematite intergrown w i t h s u l p h i d e s i s uncommon. K a r s t Episode IV - Formation of Channels (Bogaz) The p r e f e r r e d o r i e n t a t i o n of channels which e x i s t at Hawker Creek, t h e i r unusual d i s t r i b u t i o n and shape, and t h e i r common a s s o c i a t i o n w i t h massive s u l p h i d e o c c u r r e n c e s , l e d Lomenda, Olson and T r i g g (1973) to p o s t u l a t e t h a t channels were unroofed remnants of paleocaves. T h i s o r i g i n now seems u n l i k e l y because: The mechanism f o r primary d e p o s i t i o n of hematite i s d i s c u s s e d i n the s e c t i o n on Paragenesis. 131 (1) the converging, d e n d r i t i c p a t t e r n of channels more c l o s e l y resembles s u r f a c e drainage p a t t e r n s r a t h e r than the anastomos-in g o r r e c t i l i n e a r p a t t e r n s e x h i b i t e d by many cave systems, 1 (2) the f l a t , s t e p l i k e , o f t e n wide, channel f l o o r s do not p a r t i c u l a r l y resemble cave f l o o r s seen by the author o r d e s c r i b e d i n the l i t e r a t u r e , (3) channel f l o o r s commonly c o n s i s t of bare dolomite pavement without the c o l l a p s e d r o o f b r e c c i a b l o c k s which might be expected, and (4) nowhere does a channel pass i n t o an u n c o l l a p s e d cave. I t i s probable t h a t the channels are Recent s u p e r f i c i a l s o l u t i o n f e a t u r e s and should be more p r o p e r l y 3 c a l l e d bogaz (Sweeting, 1973). 4 Bogaz are a g i a n t v e r s i o n of k l u f t k a r r e n . Bogaz and k l u f t k a r r e n form by the chemical a c t i o n of water running 5 over carbonate s u r f a c e s . They develop along j o i n t s or o t h e r xSee Herak and S t r i n g f i e l d (1972) f o r examples of cave systems. 2 See Deike (1967) , Jennings (1971), Herak and S t r i n g -f i e l d (1972) and Sweeting (1973) f o r d i s c u s s i o n o f shapes of modern cave passages. 3 Bogaz have a l s o been c a l l e d strugas or zanjon by Sweeting (1973, pp. 88 and 89), and g i a n t g r i k e s , s o l u t i o n c o r r i d o r s , box v a l l e y s or k a r s t l a b y r i n t h s by Ford and Quinlan (1973, p. 15). 4 Karren are a g e n e r a l term f o r s o l u t i o n channels formed on the s u r f a c e of s o l u b l e rock i n k a r s t topography; k a r r e n range i n depth from a few m i l l i m e t e r s to more than a meter (Gary, McAfee and Wolf, 1972; Sweeting, 1973). 5 Sweeting (1973, p. 76 and p. 87) noted the importance of snow melt water to formation of karren and s t a t e d " k l u f t k a r r e n are abundant i n r e c e n t l y g l a c i a t e d l i m e s t o n e s , hence melt waters may have