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Geology and genesis of copper deposits and associated host rocks in and near the Quill Creek area, southwestern… Campbell, Susan Wendy 1981

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GEOLOGY AND GENESIS OF COPPER DEPOSITS AND ASSOCIATED HOST ROCKS IN AND NEAR THE QUILL CREEK AREA, SOUTHWESTERN YUKON by SUSAN WENDY CAMPBELL B.Sc. (Hons.), The U n i v e r s i t y o f Manitoba, 1972 M . S c , The U n i v e r s i t y o f Manitoba, 1973 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES (Department o f G e o l o g i c a l S c i e n c e s ) We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA A p r i l 1981 © Susan Wendy Campbell, 1981 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e h e a d o f my d e p a r t m e n t o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f Q- £02-0£/CflL. Sc/£AJC£S. The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 W e s b r o o k P l a c e V a n c o u v e r , C a n a d a V6T 1W5 D a t e ^ J l J L , /5~,/1$/ DE-6 ( 2 / 7 9 ) i i ABSTRACT The Kluane Ranges are u n d e r l a i n by a sequence o f s t r a t i f i e d r o c k s r a n g i n g i n age from Permian to T r i a s s i c , c u t by .Cretaceous and T e r t i a r y i n t r u s i o n s . Flow and p y r o c l a s t i c r o c k s o f Lower Permian S t a t i o n Creek Formation were p r o b a b l y p a r t o f a v o l c a n i c a r c e n v i r o n -ment. A r g i l l a c e o u s and t u f f a c e o u s r o c k s o f the T r a n s i t i o n Zone o f S t a t i o n Creek Formation and o v e r l y i n g s e d i m e n t a r y ro c k s o f Lower Permian Hasen Creek Formation were d e p o s i t e d i n a subaqueous e n v i r o n -ment, p o s s i b l y a b a c k - a r c b a s i n . Upper T r i a s s i c b a s a l t s o f the N i k o l a i Greenstone are l a r g e l y s u b a e r i a l and were p r o b a b l y a p r o d u c t o f r i f t v o l cam" sm. Lower T r i a s s i c Kluane g a b b r o - u l t r a m a f i c complexes a r e s i l l - o r s h e e t - l i k e b o d i e s , d i v i s i b l e i n t o a Lower Group ( w i t h i n the T r a n s i t i o n Zone) t h a t c o n s i s t o f p e r i d o t i t e and d u n i t e w i t h a s s o c i a t e d n i c k e l -copper s u l p h i d e d e p o s i t s , and an Upper Group ( w i t h i n Hasen Creek r o c k s ) t h a t c o n s i s t o f gabbro and p e r i d o t i t e but w i t h no known a s s o c i a t e d n i c k e l - c o p p e r d e p o s i t s . The u l t r a m a f i c r o c k s are p i a g i o c l a s e - b e a r i n g and c h e m i c a l l y a r e p y r o x e n i t i c and p e r i d o t i t i c k o m a t i i t e s . Bulk c h e m i c a l c o m p o s i t i o n o f the Q u i l l Creek complex i s s i m i l a r t o t h a t o f p y r o l i t e and c a l c u l a t i o n s show the complex c o u l d have formed from an upper mantle d i a p i r , a f f e c t e d by 40 p e r c e n t p a r t i a l m e l t i n g and composed o f r e s i d u a l o l i v i n e c r y s t a l s and u l t r a m a f i c l i q u i d . Prominent copper l o d e d e p o s i t s i n the Kluane Ranges i n c l u d e : (1) v e i n and d i s s e m i n a t e d types i n S t a t i o n Creek v o l c a n i c r o c k s ; (2) n i c k e l - c o p p e r a s s o c i a t e d w i t h Kluane complexes; and (3) v e i n - t y p e i n the N i k o l a i G r e e n s t o n e . A narrow, p o s i t i v e range o f s u l p h u r i i i i s o t o p i c c o m p o s i t i o n s f o r v e i n s u l p h i d e s i n S t a t i o n Creek Formation c o n t r a s t s h a r p l y w i t h a l a r g e range f o r those i n t h e N i k o l a i Green-s t o n e . The former d e p o s i t s r e s u l t e d from o n l y l o c a l m o b i l i z a t i o n o f s u l p h u r (and m e t a l s ) d u r i n g metamorphism i n a c l o s e d system, whereas m i n e r a l i z a t i o n i n t h e N i k o l a i Greenstone i n v o l v e d c o n s i d e r a b l e v a r i a t i o n i n c h e m i c a l parameters o f ore f l u i d s i n an open system w i t h more than one s o u r c e o f s u l p h u r . Anomalously n e g a t i v e s u l p h u r i s o t o p i c v a l u e s f o r n i c k e l - c o p p e r s u l p h i d e b o d i e s r e s u l t e d from c o n t a m i n a t i o n o f magmatic s u l p h u r by 30 t o 60 p e r c e n t s u l p h u r from w a l l r o c k s . Much o f t h i s c o n t a m i n a t i o n o c c u r r e d p r i o r t o o r d u r i n g s e g r e g a t i o n o f an i m m i s c i b l e s u l p h i d e l i q u i d as a t Q u i l l Creek, w i t h f u r t h e r c o n t a m i n a t i o n d u r i n g i n j e c t i o n o f s t i l l l i q u i d s u l p h i d e b o d i e s i n t o f o o t w a l l r o c k s i n the case o f Canala s k d e p o s i t . S u b s t a n t i a l c o n t a m i n a n t . s u l p h u r may have been c r u c i a l i n a c h i e v i n g s u l p h u r s a t u r a t i o n o f magmas o f Lower Group Kluane complexes and subsequent f o r m a t i o n o f a s s o c i a t e d n i c k e l - c o p p e r s u l p h i d e d e p o s i t s . I s o t o p i c d a t a f o r both magmatic s u l p h i d e s and s u l p h u r - b e a r i n g c o u n t r y rock s u p p o r t a s t r o n g case f o r a g e n e r a l s u l p h u r c o n t a m i n a t i o n model f o r n i c k e l - c o p p e r d e p o s i t s r e l a t e d t o m a f i c and u l t r a m a f i c i n t r u s i o n s on a worldwide s c a l e . P y r i t e i n w a l l r o c k i s c o n s i d e r e d t o be t h e most l i k e l y g e n e r a l s o u r c e o f s u l p h u r c o n t r i b u t e d t o u l t r a m a f i c magmas and s e v e r a l d i f f e r e n t s t a g e s o f s u l p h u r c o n t a m i n a t i o n a re p o s s i b l e t h r o u g h o u t c o n s o l i d a t i o n o f the magmas and i t s a s s o c i a t e d s u l p h i d e s . S u l p h u r t r a n s f e r t o the magma can o c c u r by b u l k c o u n t r y rock a s s i m i l -a t i o n o r by f l u i d i n g r e s s where t h e f l u i d d e r i v e s s u l p h u r from t he c o n t a c t zone by i n c o n g r u e n t m e l t i n g o f p y r i t e o r by complete d i s s o c i a t i o n i v o f p y r i t e . Important f e a t u r e s o f t h i s model, h a v i n g economic i m p l i c a t i o n s , a r e : (1) emplacement o f t h e u l t r a m a f i c complex as a magma; (2) presence o f s u l p h u r - b e a r i n g c o u n t r y r o c k s ; and (3) presence o f a s u l p h u r - d e p l e t i o n h a l o a d j a c e n t to the u l t r a m a f i t e . V TABLE OF CONTENTS Page ABSTRACT i i LIST OF TABLES i x LIST OF FIGURES x i LIST OF PLATES x i v ACKNOWLEDGEMENTS xv DEDICATION x v i i CHAPTER 1: INTRODUCTION 1 CHAPTER 2: GEOLOGY AND METALLOGENY OF THE QUILL CREEK AND WHITE 6 RIVER AREAS, KLUANE RANGES, YUKON TERRITORY A b s t r a c t 7 I n t r o d u c t i o n 8 Re g i o n a l S e t t i n g 9 Geology o f Q u i l l Creek Area 12 Rock Types 12 S t a t i o n Creek Formation 12 Hasen Creek F o r m a t i o n 20 N i k o l a i Greenstone 24 I n t r u s i v e Rocks 29 S t r u c t u r e and Metamorphism 33 Copper Metal!ogeny o f the S a i n t E l i as F o o t h i l l s 36 C l a s s i f i c a t i o n o f M i n e r a l D e p o s i t s 37 Copper i n S k o l a i Group 37 N i c k e l - C o p p e r A s s o c i a t e d w i t h U l t r a m a f i c 39 I n t r u s i o n s Copper i n N i k o l a i Greenstone 40 Copper-Molybdenum i n F e l s i c I n t r u s i o n s 42 Metal 1ogeny 43 G e o l o g i c a l E v o l u t i o n o f the Q u i l l Creek Area 47 v i Acknowledgements J ' 50 Re f e r e n c e s J 51 CHAPTER 3: GABBRO AND ULTRAMAFIC ROCKS OF THE KLUANE RANGES, 54 YUKON TERRITORY - CORDILLERAN KOMATIITES A b s t r a c t 55 I n t r o d u c t i o n 55 Regional S e t t i n g and Geology o f Q u i l l Creek Area 56 Kluane G a b b r o - U l t r a m a f i c Complexes 58 I n t r o d u c t i o n 58 P e t r o g r a p h y 62 C h e m i s t r y 65 S t r u c t u r e 69 A l t e r a t i o n 73 Age o f the Complexes ' 74 O r i g i n 74 G e n e r a t i o n o f the K o m a t i i t i c Magmas 80 Maple Creek Gabbros 84 C o n c l u s i o n s 86 Acknowledgements 87 Ref e r e n c e s 89 CHAPTER 4: GENETIC IMPLICATIONS OF SULPHUR ISOTOPE DATA FOR 91 MINERAL DEPOSITS IN THE KLUANE RANGES, SOUTHWESTERN YUKON TERRITORY A b s t r a c t 92 I n t r o d u c t i o n and G e o l o g i c S e t t i n g 93 A n a l y t i c a l Method and R e s u l t s 99 N i c k e l - C o p p e r D e p o s i t s 104 S u l p h u r I s o t o p e s i n the N i c k e l - C o p p e r D e p o s i t s 107 S u l p h u r I s o t o p e s i n I n t r u d e d Country Rocks 109 v i i Development o f a C o n t a m i n a t i o n Model 111 Bimodal A s p e c t o f W e l l g r e e n S u l p h u r I s o t o p e Data 115 S u l p h i d e s i n S t a t i o n Creek Formation 120 S u l p h i d e s i n N i k o l a i Greenstone 122 C o n c l u s i o n s 128 Acknowledgements 134 Re f e r e n c e s 135 CHAPTER 5: SULPHUR CONTAMINATION MODEL FOR MAGMATIC NICKEL- 138 COPPER DEPOSITS A b s t r a c t 139 H i s t o r i c a l Background 139 Ev i d e n c e f o r Magma Co n t a m i n a t i o n 141 Ev i d e n c e f o r Source o f S u l p h u r 145 Ti m i n g o f C o n t a m i n a t i o n 148 S u l p h u r C o n t a m i n a t i o n P r o c e s s 150 Bulk A s s i m i l a t i o n 150 In c o n g r u e n t M e l t i n g o f P y r i t e 153 Complete D i s s o c i a t i o n o f P y r i t e 154 Summary o f the Model 155 Economic I m p l i c a t i o n s 158 Acknowledgements 159 Re f e r e n c e s 161 CHAPTER 6: CONCLUSIONS 164 REFERENCES 171 APPENDIX A l : DETAILED GEOLOGY AND HISTORY OF DEVELOPMENT OF INDI- 179 VIDUAL PROPERTIES IN THE QUILL CREEK AND WHITE RIVER AREAS v i i i Copper i n S k o l a i Group 180 P i c k h a n d l e P r o p e r t y 180 N i c k e l - C o p p e r A s s o c i a t e d w i t h U l t r a m a f i c I n t r u s i o n s 184 Well green P r o p e r t y 184 Arch Creek P r o p e r t y 192 L i n d a Creek P r o p e r t y 195 Canal ask P r o p e r t y 197 Copper i n N i k o l a i Greenstone 203 Q u i l l Creek Mines L i m i t e d 203 A l i c e Lake Mines L i m i t e d 207 APPENDIX A2: DESCRIPTIONS OF SAMPLES OF VOLCANIC ROCKS ANALYZED 209 CHEMICALLY S t a t i o n Creek Formation 210 N i k o l a i Greenstone 212 APPENDIX A3: ANALYTICAL PRECISION FOR WHOLE ROCK AND TRACE 216 ELEMENT ANALYSES I n t r o d u c t i o n 217 A n a l y t i c a l P r e c i s i o n 217 i x LIST OF TABLES CHAPTER 2 Page T a b l e 1: T a b l e o f f o r m a t i o n s f o r Q u i l l Creek map a r e a 13 2: Whole rock c h e m i s t r y , CIPW norms, and t r a c e element 18 da t a f o r S t a t i o n Creek Formation 3: M i c r o f a u n a from i n s o l u b l e l i m e s t o n e r e s i d u e s 19 4: Whole rock c h e m i s t r y , CIPW norms, and t r a c e 28 element d a t a f o r N i k o l a i Greenstone 5: A x i a l p l a n e and a x i s d e t e r m i n a t i o n s from s t e r e o n e t 35 p l o t s o f dat a f o r f o l d s i n Q u i l l Creek and P i c k h a n d l e Lake a r e a s 6: D i s t r i b u t i o n o f m i n e r a l o c c u r r e n c e s w i t h time i n the 46 Kluane Ranges CHAPTER 3 T a b l e 1: Average m i c r o p r o b e a n a l y s i s f o r o l i v i n e , e n s t a t i t e , 64 a u g i t e , p h l o g o p i t i c b i o t i t e , and " p l a g i o c l a s e " i n l h e r z o l i t e , White R i v e r complex 2: Whole rock c h e m i s t r y , CIPW norms, and t r a c e element d a t a 68 f o r Kluane u l t r a m a f i c r o c k s 3: Whole rock c h e m i s t r y , CIPW norms, and t r a c e element d a t a 70 f o r o l i v i n e gabbro and gabbro i n Kluane complexes 4: Potassium-argon age d e t e r m i n a t i o n s on p h l o g o p i t i c b i o t i t e 75 i n Kluane g a b b r o - u l t r a m a f i c complexes 5: D e t e r m i n a t i o n o f bulk c o m p o s i t i o n o f Q u i l l Creek complex 81 and comparison w i t h p y r o l i t e c o m p o s i t i o n s 6: Composition o f l i q u i d d e r i v e d by v a r i o u s degrees o f 82 p a r t i a l m e l t i n g o f bulk c o m p o s i t i o n f o r Q u i l l Creek complex 7: D e t e r m i n a t i o n o f bulk c o m p o s i t i o n o f Upper Group gabbro- 83 u l t r a m a f i c complexes X 8: Whole rock c h e m i s t r y , CIPW norms, and t r a c e element 85 data f o r Maple Creek gabbros CHAPTER 4 Table 1: P r e - T e r t i a r y rock u n i t s and a s s o c i a t e d m i n e r a l 96 o c c u r r e n c e s i n the Kluane Ranges, Yukon 2: C l a s s i f i c a t i o n o f l o d e metal o c c u r r e n c e s , Kluane Ranges 98 3: S u l p h u r i s o t o p i c c o m p o s i t i o n s o f s u l p h i d e s i n n i c k e l - 100 cop p e r d e p o s i t s 4: S u l p h u r i s o t o p i c c o m p o s i t i o n s o f s u l p h i d e s i n S t a t i o n 101 Creek v o l c a n i c r o c k s and i n ro c k s on the T r a n s i t i o n Zone 5: S u l p h u r i s o t o p i c c o m p o s i t i o n s o f s u l p h i d e s i n N i k o l a i 102 Greenstone CHAPTER 6 T a b l e 1: Copper l o d e d e p o s i t s i n the Kluane Ranges 167 APPENDIX A l T a b l e A l : O p e r a t i n g summary f o r the Well green Mine 186 A2: Ore r e s e r v e s and grades f o r Canal ask d e p o s i t 204 APPENDIX A3 T a b l e A l : A n a l y t i c a l P r e c i s i o n f o r Major and M i n o r Elements 218 A2: A n a l y t i c a l P r e c i s i o n f o r T r a c e Elements 219 x i LIST OF FIGURES CHAPTER 2 F i g u r e 1: 2: 3: 4: L o c a t i o n map o f Kluane Ranges and S a i n t E l i as Mountains and major t e c t o n i c f e a t u r e s G e o l o g i c map o f the Q u i l l Creek area Schematic s t r a t i g r a p h i c s e c t i o n s through Hasen Creek Formation L o c a t i o n o f p r i n c i p a l base metal o c c u r r e n c e s f o r m i n g p a r t o f t h i s m e t a l l o g e n e t i c study i n the f o o t h i l l s o f S a i n t E l i as Mountains Schematic c r o s s s e c t i o n o f m i n e r a l o c c u r r e n c e s and s t r a t i g r a p h y i n Kluane Ranges CHAPTER 3 F i g u r e 1: G e o l o g i c map o f Q u i l l Creek a r e a , showing l o c a t i o n s o f Kluane complexes 2: Schematic c r o s s s e c t i o n o f s t r a t i g r a p h i c p o s i t i o n s o f Kluane complexes 3: G e o l o g i c map and c r o s s s e c t i o n s o f Well green p r o p e r t y 4: Chemical f i e l d s o f Kluane complexes, Maple Creek gabbros, and N i k o l a i Greenstone b a s a l t s 5: Cross s e c t i o n o f s t r u c t u r a l r e l a t i o n s among gabbro, p e r i d o t i t e , and s u l p h i d e ore types a t Well green Mine 6 : Cross s e c t i o n s showing m i n e r a l modes f o r Q u i l l Creek complex and Arch Canyon complex 7: Schematic r e c o n s t r u c t i o n o f p o s s i b l e o r i g i n a l Q u i l l Creek - Arch Creek - Arch Canyon complex 8: Cross s e c t i o n o f rock types and modal v a r i a t i o n i n x i i the Burwash Creek complex CHAPTER 4 F i g u r e 1: L o c a t i o n map o f base metal d e p o s i t s i n the f o o t h i l l s 94 o f S a i n t E l i as Mountains 2: Schematic c r o s s s e c t i o n o f m i n e r a l o c c u r r e n c e s and 97 s t r a t i g r a p h y i n the Kluane Ranges 3: P a r t i t i o n i n g o f s u l p h u r i s o t o p e s i n the p a i r 103 p y r r h o t i t e - c h a l c o p y r i t e from Well green n i c k e l -c o p p e r d e p o s i t 4: Cross s e c t i o n o f s t r u c t u r a l r e l a t i o n s among gabbro, 105 p e r i d o t i t e , and s u l p h i d e ore types a t Well green Mine 5: S u l p h u r i s o t o p i c data f o r Well g r e e n , Arch Creek, and 108 C a n a l a s k n i c k e l - c o p p e r d e p o s i t s and f o r a s e l e c t i o n o f o t h e r g a b b r o i c and u l t r a m a f i c i n t r u s i o n s 6: S u l p h u r i s o t o p i c c o m p o s i t i o n s f o r s u l p h i d e s i n 110 C a n a l a s k , Well g r e e n , and A r c h Creek n i c k e l - c o p p e r d e p o s i t s and f o r s u l p h i d e s i n c o u n t r y r o c k s 7: S u l p h u r i s o t o p i c c o m p o s i t i o n s f o r n i c k e l - c o p p e r 116 s u l p h i d e o r e i n both gabbro and massive ore f o r Well green and Arch Creek d e p o s i t s 8: I d e a l i z e d d i s t r i b u t i o n o f average s u l p h u r i s o t o p e 118 v a l u e s f o r Well green and Arch Creek d e p o s i t s o f the Q u i l l Creek p e r i d o t i t i c complex 9: Geology o f p a r t o f P i c k h a n d l e p r o p e r t y , showing 121 r e l a t i o n o f m i n e r a l o c c u r r e n c e s t o rock u n i t s 10: G e o l o g i c c r o s s s e c t i o n f o r S i l v e r C i t y p r o p e r t y , 124 showing rock u n i t s and zone o f g r e a t e r than 0.1 p e r c e n t copper 11: S u l p h u r i s o t o p i c c o m p o s i t i o n s f o r copper d e p o s i t s 126 i n N i k o l a i Greenstone a t S i l v e r C i t y , Q u i l l Creek Mines, A l i c e Lake Mines p r o p e r t i e s , and Johobo Mine 12: S t a b i l i t i e s o f predominant aqueous s u l p h u r - c o n t a i n i n g 127 s p e c i e s as f u n c t i o n s o f f g , and pH a t 250°C, and w i t h superimposed s t a b i l i t y f i e l d s f o r p y r i t e , m a g n e t i t e , and h e m a t i t e 13: I n f l u e n c e o f f g 9 and pH on i s o t o p i c c o m p o s i t i o n o f 129 xi i i s u l p h u r s p e c i e s f o r T=250°C, 1 = 1.0, and t> 3 4S y c- = +22.4 p e r m i l 14: Schematic diagrams f o r g e n e r a t i o n o f lode copper 131 d e p o s i t s i n Kluane Ranges: (a) n i c k e l - c o p p e r s u l p h i d e s a s s o c i a t e d w i t h u l t r a m a f i c r o c k s ; (b) s u l p h i d e s i n S t a t i o n Creek v o l c a n i c r o c k s ; and (c) s u l p h i d e s i n b a s a l t flows o f N i k o l a i Greenstone CHAPTER 5 F i g u r e 1: S u l p h u r i s o t o p i c data f o r Well g r e e n , Arch Creek, and 144 Canalask n i c k e l - c o p p e r d e p o s i t s and f o r a s e l e c t i o n 1 o f o t h e r g a b b r o i c and u l t r a m a f i c i n t r u s i o n s 2: C o m p i l a t i o n o f s u l p h u r i s o t o p i c data f o r n i c k e l - 147 copper s u l p h i d e s a s s o c i a t e d w i t h g a b b r o i c and u l t r a m a f i c r o c k s , which show e v i d e n c e o f co n t a m i -n a t i o n , and f o r s u l p h i d e s i n w a l l r o c k s o r i n t r u d e d c o u n t r y r o c k s 3: Schematic r e p r e s e n t a t i o n o f s u l p h u r c o n t a m i n a t i o n 157 model f o r g a b b r o i c o r u l t r a m a f i c i n t r u s i o n s APPENDIX A l F i g u r e A l A2 A3 A4 A5 G e o l o g i c map o f P i c k h a n d l e Lake p r o p e r t y G e o l o g i c map o f Well green p r o p e r t y G e o l o g i c map o f Arch Creek p r o p e r t y G e o l o g i c map o f L i n d a Creek p r o p e r t y G e o l o g i c map o f Canalask p r o p e r t y -Map-Pocket <• - • G o 1 ; f '-^ -Map-Poeket-• Map-Pocket -Map-Pocket -Map-Pocket-XI V LIST OF PLATES Page CHAPTER 2 P l a t e 1: T h i n l y bedded f i n e - t o medium-grained t u f f a c e o u s 15 b a s a l t i c a n d e s i t e o f S t a t i o n Creek Formation 2: Massive v o l c a n i c b r e c c i a (more a n d e s i t i c than 16 u n d e r l y i n g t u f f s ) o f S t a t i o n Creek F o r m a t i o n , showing p a l e r green to g r e y - g r e e n fragments i n a d a r k e r green m a t r i x . 3: P a l e green to g r e y - w h i t e c h e r t y a r g i l l i t e 21 and a r g i l l i t e o f Hasen Creek Formation showing l a y e r i n g and f o l d i n g 4: Deformed s h a l e and s i l t s tone i n lower p a r t s o f 22 Hasen Creek s e d i m e n t a r y sequence 5: C o n t a c t , a p p a r e n t as a c o l o r change from green 26 t o r e d d i s h - b r o w n , between two b a s a l t f l o ws o f the N i k o l a i Greenstone 6: C h a r a c t e r i s t i c a m y g d a l o i d a l n a t u r e o f b a s a l t f l o ws 27 o f t h e N i k o l a i Greenstone-7: Sharp i n t r u s i v e c o n t a c t between an u l t r a m a f i t e s t r i n g e r 30 o f a Kluane complex and w a l l rock. 8: Small x e n o l i t h , showing s h a r p t o hazy c o n t a c t s w i t h 31 p e r i d o t i t e , found w i t h i n b a s a l p a r t s o f t h e Q u i l l Creek complex XV ACKNOWLEDGEMENTS The w r i t e r would l i k e t o thank Dr. K.C. McTaggart f o r f i r s t mention-i n g Well green Mine and the Kluane Ranges as a p o s s i b l e s t u d y a r e a . S p e c i a l thanks go t o Dr. A . J . S i n c l a i r f o r h i s g u i d a n c e , encouragement, and f i n a n c i a l s u p p o r t as s u p e r v i s o r d u r i n g the co u r s e o f t h i s s t u d y and t o the t h e s i s committee members, Drs. K.C. McTaggart, C . I. Godwin, and J.W.H. Monger, f o r t h e i r h e l p and u s e f u l d i s c u s s i o n s . Dr. A.E. S o r e g a r o l i p r o v i d e d guidance and f i n a n c i a l s u p p o r t d u r i n g t he e a r l i e s t s t a g e s o f the 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 was p r o v i d e d l a r g e l y by the N a t i o n a l Research C o u n c i l o f Canada through a P o s t g r a d u a t e S c h o l a r s h i p t o the w r i t e r and o p e r a t i n g g r a n t s t o Dr. A . J . S i n c l a i r . Other f i n a n c i a l s u p p o r t was r e c e i v e d from Department o f I n d i a n and N o r t h e r n A f f a i r s , t h e A r c t i c and A l p i n e I n s t i t u t e o f the U n i v e r s i t y o f B r i t i s h Columbia, Western Mines L i m i t e d , and Orequest E x p l o r a t i o n , Vancouver. F i e l d s u p p o r t was g e n e r o u s l y p r o v i d e d by Dr. R.B. Campbell o f the G e o l o g i c a l S u r v e y o f Canada and Dr. D.B. C r a i g o f the Department o f I n d i a n and No r t h e r n A f f a i r s . The w r i t e r would l i k e t o thank J . Borakso o f Min-En L a b o r a t o r i e s , Vancouver, f o r p r o v i d i n g c h e m i c a l a n a l y s e s a t a s u b s t a n t i a l l y reduced r a t e . F o s s i l d e t e r m i n a t i o n s were p r o v i d e d c o u r t e s y o f P.B. Read and B.E.B. Cameron w h i l e a t the G e o l o g i c a l Survey o f Canada, Vancouver. The w r i t e r thanks D r s . O.R. E c k s t r a n d and R.V. Ki.rkham o f the G e o l o g i c a l Survey o f Canada, Ottawa, who k i n d l y a c c e p t e d t h e s i s samples f o r s u l p h u r i s o t o p i c a n a l y s e s and s u p p l i e d i s o t o p i c d a t a on specimens they had c o l l e c t e d from copper l o d e d e p o s i t s i n the f o o t h i l l s o f S a i n t E l i as Mountains. Many thanks t o Dr. A.E. S o r e g a r o l i and Western Mines L i m i t e d f o r r e l e a s i n g a l l d a t a x v i on P i c k h a n d l e Lake p r o p e r t y f o r use i n t h i s t h e s i s . Numerous peop l e gave o f t h e i r time i n u s e f u l d i s c u s s i o n s , i n c l u d i n g Dr. R.B. Campbell, Dr. P.B. Read, Dr. O.R. E c k s t r a n d , C.A. A i r d , D. Tenny, R. F r e e b e r g , J . V i n c e n t , V. A h l b o r n , J.R. Woodcock, R. C h e r l e t , A. Macdonald, R. M a c i n t o s h , W. Green, and the l a t e P. V e r s l u c e . Many thanks t o Dr. R.L. Armstrong, K. S c o t t , S. Horsky, N. S t a c e y , J . E . H a r a k a l , and E. Montgomery and h i s t e c h n i c a l s t a f f , f o r t h e i r a d v i c e and/or h e l p d u r i n g v a r i o u s types o f l a b work. The w r i t e r would l i k e t o thank S. Wong and e s p e c i a l l y A. Kemp and J . Newlands f o r t h e i r e x c e l l e n t d r a f t i n g o f the maps and f i g u r e s . S p e c i a l thanks go t o J . Campbell who managed through i l l e g i b l e h a n d w r i t i n g t o type an i n i t i a l d r a f t o f the t h e s i s . A l s o , many thanks t o C. Sawyer who t y p e d the f i n a l d r a f t o f t h i s t h e s i s . Her p a t i e n c e , e x p e r t i s e , and e n t h u s i a s m are g r e a t l y a p p r e c i a t e d . Many people p r o v i d e d encouragement d u r i n g r e l a t i v e l y n o n - p r o d u c t i v e p e r i o d s o f the s t u d y , i n c l u d i n g Drs. M. B a r n e s , W. B a r n e s , and H.J. Green-wood. I would l i k e t o thank Drs. A . J . S i n c l a i r and K.C. McTaggart f o r t h e i r p a t i e n c e , c o n t i n u e d s u p p o r t , and encouragement d u r i n g the f i n a l y e a r o f t h i s s t u d y . L a s t l y , s p e c i a l thanks t o the p e o p l e o f P l a c e r Development L i m i t e d , Vancouver, e s p e c i a l l y D.C. Rotherham, D.A. Howard, and S . J . Tennant, who a l l o w e d the t h e s i s t o take p r i o r i t y d u r i n g the w r i t e r ' s employment a t P l a c e r s i n c e the s p r i n g o f 1980. ;xvii To the memory o f my f a t h e r CHAPTER 1 INTRODUCTION 2 The Kluane Ranges a r e a n o r t h w e s t e r l y - t r e n d i n g s t r i n g o f mountains between A l s e k and White R i v e r s i n the southwestern c o r n e r o f Yukon T e r r i t o r y . These and the more w e s t e r l y Donje'k Ranges form the f o o t h i l l s o f the S a i n t E l i as Mountains. Numerous s m a l l copper l o d e d e p o s i t s o f v a r i o u s types a r e s c a t t e r e d t h r o u g h o u t the Kluane Ranges i n a v a r i e t y o f h o s t r o c k s . Dominant rock u n i t s i n the a r e a a r e Lower Permian S t a t i o n Creek and Hasen Creek F o r m a t i o n s , and Upper T r i a s s i c N i k o l a i G r e e n s t o n e . S t a t i o n Creek Formation c o n s i s t s o f b a s a l t i c a n d e s i t e f l o w s , t u f f s , and a g g l o m e r a t e s . The upper 400 m o f t h i s f o r m a t i o n i s h e r e i n c a l l e d t h e T r a n s i t i o n Zone, a zone o f s h a l e s , a r g i l l i t e s , and i n t e r c a l a t e d t u f f s . T h i s g r a d a t i o n a l zone i s o v e r l a i n by Hasen Creek F o r m a t i o n , c o n s i s t i n g o f a r g i l l i t e , s h a l e , s i l t s t o n e , l i m e s t o n e , minor greywacke, and c o n g l o m e r a t e . N i k o l a i G r e enstone, a sequence o f a m y g d a l o i d a l b a s a l t f l o w s , d i s c o n f o r m a b l y o v e r l i e s Hasen Creek s e d i m e n t a r y r o c k s . Upper T r i a s s i c C h i t i s t o n e and N i z i n a l i m e s t o n e s a r e p r e s e n t l o c a l l y i n the Kluane Ranges. I n t r u s i v e r o c k s i n c l u d e Lower T r i a s s i c g a b b r o - u l t r a m a f i c s i l l s (Kluane c o m p l e x e s ) , Upper T r i a s s i c gabbro dykes and s i l l s (Maple Creek g a b b r o s ) , C r e t a c e o u s Kluane Range i n t r u s i o n s , and T e r t i a r y q u a r t z l a t i t e p o rphyry s t o c k s and dykes. The Kluane complexes i n t r u d e both the T r a n s i t i o n Zone o f S t a t i o n Creek Formation and s e d i m e n t a r y r o c k s o f Hasen Creek F o r m a t i o n . Maple Creek gabbros i n t r u d e a l l Lower Permian u n i t s and the Upper T r i a s s i c b a s a l t s . A l t h o u g h l o d e c o p p e r d e p o s i t s were d i s c o v e r e d b e f o r e the t u r n o f the c e n t u r y , a t t e n t i o n d u r i n g the e a r l y n i n e t e e n hundreds f o c u s e d on p l a c e r g o l d and c o p p e r o c c u r r e n c e s t h r o u g h o u t the f o o t h i l l s o f S a i n t E l i a s M o untains. P l a c e r c o p p e r d e p o s i t s were s t a k e d on Upper White R i v e r i n 1905 and on Q u i l l and Tatamagouche Creeks i n 1914. I n t e r e s t i n l o d e 3 d e p o s i t s was s p a r k e d i n 1952 when n i c k e l - c o p p e r s u l p h i d e d e p o s i t s were d i s c o v e r e d i n the Q u i l l Creek a r e a o f the Kluane Ranges. D e s p i t e t h e abundance o f lo d e o c c u r r e n c e s , o n l y two o p e r a t i n g mines e x i s t e d i n the Kl u a n e s ; Johobo Mine, a p r o d u c e r o f copper and s i l v e r between 1958 and 1962, and W e l l g r e e n Mine, a p r o d u c e r o f n i c k e l , c o p p e r , p l a t i n u m , and c o b a l t , i n 1972 and 1973. S i n c e t h e mid n i n e t e e n s e v e n t i e s , the Kluane a r e a has remained i n a c t i v e e x c e p t f o r p l a c e r g o l d o p e r a t i o n s a l o n g Burwash and o t h e r C r e e k s . D e s p i t e c o n s i d e r a b l e p r o s p e c t i n g and e x p l o r a t i o n through the y e a r s , r e l a t i v e l y l i t t l e emphasis was p l a c e d on g e n e s i s o f the copper l o d e d e p o s i t s and t h e i r h o s t r o c k s . A p e t r o l o g i c a l and s t r u c t u r a l s t u d y o f Q u i l l Creek and White R i v e r complexes and t h e i r a s s o c i a t e d n i c k e l - c o p p e r s u l p h i d e d e p o s i t s by Campbell (1960) was the o n l y p u b l i s h e d a c c o u n t a t t e m p t i n g t o d e f i n e t h e o r i g i n o f thes e b a d l y s h e a r e d and a l t e r e d r o c k s and t h e i r o r e s . E c k s t r a n d (1972) and Kirkham (1972) i n c l u d e d the Kluane n i c k e l - c o p p e r d e p o s i t s and copper i n N i k o l a i G r e e n s t o n e , r e s p e c t i v e l y , i n t h e i r c l a s s i -f i c a t i o n schemes f o r Canadian d e p o s i t s . The main purpose • o f t h i s work was the a p p l i c a t i o n o f i n t e n s i v e f i e l d g e o l o g i c mapping and p e t r o - c h e m i c a l and i s o t o p i c s t u d i e s t o the problems o f g e n e s i s o f the copper l o d e d e p o s i t s , o r i g i n o f a s s o c i a t e d v o l c a n i c and p l u t o n i c h o s t r o c k s , and d e f i n i t i o n o f the m e t a l l o g e n i c e v o l u t i o n o f copper i n the Kluane Ranges. Of p a r t i c u l a r i n t e r e s t were the b a s a l t i c a n d e s i t e s and b a s a l t s and g a b b r o - u l t r a m a f i c complexes, which a r e s p a t i a l l y r e l a t e d a l o n g a r e l a t i v e l y narrow l i n e a r b e l t and c o n t a i n the m a j o r i t y o f the copper l o d e d e p o s i t s . Emphasis was p l a c e d on the Kluane complexes w i t h r e s p e c t t o t h e i r g e o l o g i c e n v i r o n m e n t , magmatic s o u r c e , mode o f emplacement, and f o r m a t i o n o f a s s o c i a t e d n i c k e l - c o p p e r s u l p h i d e s . 4 Three f i e l d s e a s o n s , 1974 t o 1976, were s p e n t i n the Q u i l l Creek and White R i v e r a r e a s o f t h e Kluane Ranges t o complete r e g i o n a l g e o l o g i c mapping o f t h e Q u i l l Creek a r e a a t a s c a l e o f 1:50,000 and d e t a i l e d mapping and s a m p l i n g o f f o u r n i c k e l - c o p p e r p r o p e r t i e s and one p r o p e r t y w i t h c o p p e r i n S t a t i o n Creek b a s a l t i c a n d e s i t e . Two p r o p e r t i e s w i t h copper i n N i k o l a i Greenstone were b r i e f l y examined. Sampling was c o n d u c t e d f o r p e t r o g r a p h i c and m i n e r a l o g r a p h i c s t u d i e s , whole rock and t r a c e element g e o c h e m i s t r y , and s u l p h u r i s o t o p e d e t e r m i n a t i o n s . The f o l l o w i n g formal papers p r e s e n t the r e s u l t s o f t h i s s t u d y . General geology and m e t a l l o g e n y o f Kluane Ranges a r e p r e s e n t e d i n Chapter 2. The geology o f Q u i l l Creek a r e a and d e t a i l e d g e o l o g y o f p r o p e r t i e s a t Well g r e e n , A r c h Creek, L i n d a Creek, C a n a l a s k , and P i c k h a n d l e Lake a r e d e s c r i b e d and types o f m i n e r a l d e p o s i t s o u t l i n e d . A s y n t h e s i s o f t h i s i n f o r m a t i o n l e a d s t o an i n t e r p r e t a t i o n o f t h e g e o l o g i c environment and m e t a l l o g e n i c e v o l u t i o n o f c o p p e r . The f i e l d r e s u l t s and i n t e r p r e t a t i o n s summarized i n Chapter 2 p r o v i d e t h e i m p o r t a n t g e o l o g i c data base, from which subsequent s t u d i e s and i n t e r -p r e t a t i o n s emerge. The Kluane g a b b r o - u l t r a m a f i c complexes a r e o f p a r t i c u l a r i n t e r e s t because o f t h e i r a s s o c i a t e d n i c k e l - c o p p e r s u l p h i d e o r e s . Such d e p o s i t s a r e r e l a t i v e l y s c a r c e i n the Canadian C o r d i l l e r a , y e t i n the K l u a n e s , form t h e most s u b s t a n t i a l o f t h e l o d e d e p o s i t s . In C h a p t e r 3 the p e t r o g r a p h i c , c h e m i c a l , and s t r u c t u r a l f e a t u r e s o f the g a b b r o - u l t r a m a f i c complexes a r e p r e s e n t e d and t h e i r c l a s s i f i c a t i o n and g e n e s i s i n t e r p r e t e d . C h a p t e r 4 p r e s e n t s a g e n e r a l s u l p h u r i s o t o p e s t u d y o f t h r e e types o f c o p p e r l o d e d e p o s i t s . The d i s t r i b u t i o n o f i s o t o p i c v a l u e s i n each type o f d e p o s i t i s a n a l y s e d and t h e i m p l i c a t i o n s r e g a r d i n g g e n e s i s and s o u r c e o f s u l p h u r a r e d i s c u s s e d . C o n c l u s i o n s f o r the n i c k e l - c o p p e r d e p o s i t s 5 l e d t o development o f a s u l p h u r c o n t a m i n a t i o n model f o r n i c k e l - c o p p e r s u l p h i d e o r e s as o u t l i n e d i n C h a p t e r 5. T h i s model i s d e v e l o p e d w i t h r e f e r e n c e t o r e s u l t s from the s t u d y o f the Well green and Canalask d e p o s i t s and t o abundant i n f o r m a t i o n i n the l i t e r a t u r e . The l a s t c h a p t e r , C h a p t e r 6, p r e s e n t s a summary o f c o n c l u s i o n s from each o f the f o r g o i n g p a p e r s . 6 CHAPTER 2 GEOLOGY AND METALLOGENY  OF THE QUILL CREEK AND WHITE RIVER AREAS, KLUANE RANGES, SOUTHWESTERN YUKON TERRITORY 7 ABSTRACT Permo-Tn'assic r o c k s dominate the geology o f Q u i l l Creek and White R i v e r a r e a s o f the Kluane Ranges. O l d e s t r o c k s a r e b a s a l t i c a n d e s i t e flows and p y r o c l a s t i c s o f the Lower Permian S t a t i o n Creek F o r m a t i o n . The upper 400 m o f t h i s f o r m a t i o n marks a g r a d a t i o n a l c o n t a c t o r T r a n s i t i o n Zone w i t h o v e r l y i n g Hasen Creek Formation. The T r a n s i t i o n Zone i s c h a r a c t e r i z e d by p y r i t i c a r g i l l a c e o u s s e d i m e n t a r y r o c k s , minor l i m e s t o n e , and i n t e r c a l a t e d t u f f a c e o u s m a t e r i a l . Lower Permian Hasen Creek s e d i m e n t a r y sequence p r o g r e s s e s upward from a r g i l l a c e o u s r o c k s t o l i m e s t o n e and minor c o a r s e c l a s t i c r o c k s . D i s -c o n f o r m a b l y o v e r l y i n g the Hasen Creek Formation are a m y g d a l o i d a l b a s a l t flows o f Upper T r i a s s i c N i k o l a i G r e e nstone. Lower T r i a s s i c Kluane g a b b r o - u l t r a m a f i c complexes i n t r u d e the Lower Permain sequence and Upper T r i a s s i c Maple Creek gabbros i n t r u d e i n t o the N i k o l a i . F e l s i c i n t r u s i o n s i n c l u d e C r e t a c e o u s g r a n o d i o r i t i c p l u t o n s and T e r t i a r y q u a r t z l a t i t e p o r p h y r y . Deformation and low grade r e g i o n a l metamorphism o c c u r r e d d u r i n g the C r e t a c e o u s . Rocks o f the Kluane Ranges are noted f o r t h e i r abundant small c o p p e r l o d e d e p o s i t s . These i n c l u d e c o p p e r - i r o n i n both S t a t i o n Creek and N i k o l a i v o l c a n i c r o c k s , n i c k e l - c o p p e r i n g a b b r o - u l t r a m a f i c complexes, and copper-molybdenum i n T e r t i a r y s t o c k s . The d e p o s i t s a r e r e l a t e d s p a t i a l l y t o a r o u g h l y 10 km wide m i n e r a l i z e d b e l t t r e n d i n g n o r t h w e s t e r l y . Lower T r i a s s i c magmatic n i c k e l - c o p p e r d e p o s i t s r e p r e s e n t the f i r s t appearance o f e c o n o m i c a l l y i m p o r t a n t d e p o s i t s i n the b e l t and p r e - d a t e r e g i o n a l d e f o r m a t i o n . Metamorphic-hydrothermal c o p p e r - i r o n v e i n d e p o s i t s a r e a l s o w i d e s p r e a d , o c c u r r i n g i n S t a t i o n Creek and N i k o l a i v o l c a n i c r o c k s . 8 The a v a i l a b i l i t y o f m e t a l s i n h o s t r o c k s and the p r e s e n c e o f s u l p h u r i n p y r i t i c w a l l r o c k s proved i m p o r t a n t t o the f o r m a t i o n o f the c o p p e r d e p o s i t s . Environments o f d e p o s i t i o n o f t h e h o s t r o c k s and g e n e s i s o f the v a r i o u s types o f l o d e copper d e p o s i t s s u g g e s t t h a t Permian and T r i a s s i c r o c k s o f t h e Kluane Ranges may have o r i g i n a t e d i n an i s l a n d a r c -m a r g i n a l b a s i n t e c t o n i c environment. INTRODUCTION The Kluane Ranges, i n *the southwestern c o r n e r o f Yukon T e r r i t o r y , l i e p a r a l l e l t o and on t h e west s i d e o f Shakwak T r e n c h , a major n o r t h -w e s t e r l y - t r e n d i n g l i n e a m e n t which c o n t a i n s Kluane Lake. The G e o l o g i c a l Survey o f Canada began mapping i n t h i s a r e a i n 1905, r e s u l t i n g i n R.G. M c C o n n e l l ' s r e p o r t on p l a c e r g o l d d e p o s i t s and g e n e r a l bedrock geology ( M c C o n n e l l , 1906). P r o s p e c t o r s d i s c o v e r e d s i g n i f i c a n t p l a c e r ground i n the e a r l y 1900's and p l a c e r copper was s t a k e d on upper White R i v e r i n 1905. C a i r n e s (1915) mapped the White R i v e r a r e a i n 1913, c o n c e n t r a t i n g on o c c u r r e n c e s o f p l a c e r g o l d , c o p p e r , and c o a l , but a l s o i n c o r p o r a t i n g some mapping o f bedrock g e o l o g y i n t o a r e v i s i o n o f M cConnell's e a r l i e r g e o l o g i c map. About one y e a r a f t e r C a i r n e s ' work, p l a c e r copper o c c u r r e n c e s on Tatamagouche and Q u i l l Creeks were d i s c o v e r e d and s t a k e d . G e o l o g i c a l r e c o n n a i s s a n c e a l o n g the A l a s k a Highway was completed by H.S. Bostock i n 1945 ( B o s t o c k , 1952). H i s map i n c o r p o r a t e s a l l p r e v i o u s work. J . E . M u l l e r c o n d u c t e d g e o l o g i c f i e l d work i n the Kluane Lake map s h e e t from 1950 through 1953 and a g a i n i n 1956 ( M u l l e r , 1967). The r e s u l t i n g map was completed a t a s c a l e o f 1:250,000 (115G, 115F Eh). 9 A s t a k i n g r u s h o c c u r r e d i n 1952 and 1953 f o l l o w i n g the d i s c o v e r y o f n i c k e l - c o p p e r d e p o s i t s i n the Q u i l l Creek a r e a . The r e s u l t s o f d e t a i l e d g e o l o g i c mapping o f s t r a t i g r a p h y i n the Kluane and A l s e k Ranges s o u t h o f Burwash Creek are p r e s e n t e d i n Read and Monger (1976) and Read (1976). A p r e l i m i n a r y r e p o r t on t h e g e o l o g y and s u l p h i d e o c c u r r e n c e s o f t h e Q u i l l Creek and White R i v e r areas i s g i v e n i n Campbell (1976). T h i s paper p r e s e n t s t h e s t r a t i g r a p h y and s t r u c t u r e o f Q u i l l Creek a r e a , a 250 square k i l o m e t e r segment o f t h e Kluane Ranges n o r t h o f Burwash Creek and e a s t o f Donjek R i v e r . F i e l d work c o n c e n t r a t e d on Lower Permian b a s a l t i c a n d e s i t e s , Lower T r i a s s i c g a b b r o - u l t r a m a f i c complexes, and Upper T r i a s s i c b a s a l t f l o w s . D e t a i l e d geology o f i n d i v i d u a l p r o p e r t i e s i n both t h e Q u i l l Creek and White R i v e r areas i s p r e s e n t e d i n Appendix A l . The Upper P a l e o z o i c t o C e n o z o i c r o c k s o f t h e Kluane Ranges c o n t a i n numerous t y p e s o f l o d e copper d e p o s i t s . Important f e a t u r e s o f t h e s e d e p o s i t s a r e d e s c r i b e d , t h e i r d i s t r i b u t i o n i n space and time o u t l i n e d , and a g e n e r a l s y n t h e s i s o f the m e t a l l o g e n i c e v o l u t i o n o f copper i s d e v e l o p e d . REGIONAL SETTING The Kluane Ranges are c o n t a i n e d w i t h i n a major s t r u c t u r a l p r o v i n c e o f the Canadian C o r d i l l e r a known as the S a i n t E l i a s F o l d B e l t . T h i s b e l t c u r v e s n o r t h w e s t e r l y to the E a s t e r n A l a s k a Range and Wrangell Mountains o f A l a s k a . The I n s u l a r B e l t extends south from the S a i n t E l i a s F o l d B e l t w i t h Chatham S t r a i t F a u l t a c t i n g as a d i v i s i o n ( F i g u r e 1 ) . 10 F i g u r e 1. L o c a t i o n map o f the Kluane Ranges and S a i n t E l i as Mountains and major t e c t o n i c f e a t u r e s o f southwestern Yukon T e r r i t o r y , namely, Shakwak-Da l t o n F a u l t , Duke R i v e r F a u l t , and F a i r w e a t h e r F a u l t . 11 Rocks o f t h e Kluane Ranges have been i n c l u d e d i n the T a k u - S k o l a i T e r r a n e (Berg ejt a l _ . , 1972) and, more r e c e n t l y , i n W r a n g e l l i a , a d i s -p l a c e d t e r r a n e e x t e n d i n g from the E a s t e r n A l a s k a Range t o Chatham S t r a i t F a u l t (Jones e t a l _ . , 1977) The Kluane Ranges a r e f a u l t - b o u n d e d . Duke R i v e r F a u l t , t o the s o u t h -west, has a m a i n l y v e r t i c a l to n e a r v e r t i c a l d i p and s e p a r a t e s Permo-T r i a s s i c r o c k s o f t h e Kluane Ranges from m i d d l e P a l e o z o i c s e d i m e n t a r y r o c k s o f t h e S a i n t E l i a s Mountains (Campbell and Dodds, 1975). Shakwak F a u l t , t o t h e n o r t h e a s t , i s a p p a r e n t l y s t e e p l y d i p p i n g and s e p a r a t e s the Kluane Ranges f r o m Precambrian metamorphic ro c k s and M e s o z o i c t o C e n o z o i c g r a n i t i c i n t r u s i o n s o f t h e Yukon C r y s t a l l i n e Complex (Tempelman-Kluit, 1976). T h i s f a u l t i s p a r t o f t h e Dalton-Shakwak-Denali F a u l t System ( E i s b a c h e r , 1976). S m a l l e r s c a l e f a u l t i n g i s p r e s e n t a l o n g the l e n g t h o f the Kluane Ranges. These f a u l t s s t r i k e n o r t h w e s t e r l y and appear t o be s t e e p l y d i p p i n g to v e r t i c a l . The d e n s i t y o f f a u l t s i n c r e a s e s to the s o u t h e a s t as Duke R i v e r F a u l t approaches t h e D a l t o n F a u l t (see g e o l o g i c maps o f M u l l e r (1976) and Read ( 1 9 7 6 ) ) . Major f o l d axes s t r i k e p a r a l l e l t o n o r t h w e s t e r l y t r e n d i n g f a u l t s mentioned above. These f o l d s a r e t i g h t t o i s o c l i n a l , i n c l i n e d t o the southwest, and i n t u r n have been f o l d e d about n o r t h e a s t axes i n t o a s e r i e s o f c u l m i n a t i o n s and d e p r e s s i o n s e x t e n d i n g the l e n g t h o f the Kluane Ranges. Dominant l i t h o l o g i e s o f t h e Kluane Ranges i n c l u d e : b a s a l t i c a n d e s i t e flows and p y r o c l a s t i c s ; an a r g i l l i t e - l i m e s t o n e - g r e y w a c k e s u c c e s s i o n ; b a s a l t i c f l o w s ; u l t r a m a f i c r o c k s ; and g r a n i t i c i n t r u s i o n s . Read (1976) d e s c r i b e s a s o u t h e a s t w a r d g r a d a t i o n from Permian 12 p y r o c l a s t i c and s e d i m e n t a r y u n i t s n o r t h o f Duke R i v e r t o dominant flows w i t h l e s s e r p y r o c l a s t i c rocks and o n l y minor i n t e r b e d d e d l i m e s t o n e and p h y l l i t e between Duke and S l i m s R i v e r . The Permian s e d i m e n t a r y r o c k s a l s o show a southward l i t h o f a c i e s change from c h e r t y a r g i l l i t e -greywacke-conglomerate w i t h l i m e s t o n e and c h e r t t o d o m i n a n t l y p h y l l i t e and c o n g l o m e r a t e . GEOLOGY OF QUILL CREEK AREA Rock Types The Permian v o l c a n i c and s e d i m e n t a r y u n i t s and T r i a s s i c b a s a l t i c s e c t i o n exposed w i t h i n the Kluane Ranges have been c o r r e l a t e d w i t h map u n i t s o f t h e T a k u - S k o l a i T e r r a n e found t o t h e n o r t h w e s t i n E a s t e r n A l a s k a Ranges (Smith and MacKevett, 1970; M a c k e v e t t , 1971; Berg e t a l _ . , 1972; Read and Monger, 1976). T a b l e 1 l i s t s t he g e o l o g i c f o r m a t i o n s f o r the Q u i l l Creek map a r e a and t h e geology i s shown i n F i g u r e 2. S t a t i o n Creek Formation S t a t i o n Creek Formation u n d e r l i e s a l l o t h e r map u n i t s i n the s t r a t i g r a p h i c s e c t i o n s t u d i e d . The base o f t h i s f o r m a t i o n i s not exposed, but Read and Monger (1976) d e s c r i b e a g a b b r o i c complex west o f Donjek R i v e r which may r e p r e s e n t t h e basement o f t h e P e r m o - T r i a s s i c sequence. Potassium-argon age f o r u r a l i t i c hornblende i n t h i s gabbro i s 475 Ma (Monger, 1977). S t a t i o n Creek F o r m a t i o n , about 1200 m t h i c k , v a r i e s from a lower s e c t i o n o f v o l c a n i c flows upward through f i n e - t o medium-grained t u f f s . L o c a l l y , t h e t u f f s a r e o v e r l a i n by agglomerate and v o l c a n i c b r e c c i a . D i s c o n t i n u o u s beds o f l i m e s t o n e and a r g i l l i t e o c c u r w i t h i n t h i s map 13 TABLE 1. Table of Formations for Qui l l Creek Map Area ERA PERIOD ROCK UNIT LITHOLOGY Cenozoic Quaternary Tert iary Mesozoic Cretaceous Upper Tr iass ic disconformity _ intrusive contact Kluane Range Intrusions _ intrusive contact Nikolai Greenstone Glacial s i l t s , sands, and gravels. Quartz l a t i t e porphyry Hornblende-bioti te granodiori te. Amygdaloidal basalt f lows, with minor limestone and shale. Lower Tr iass ic Paleozoic Lower Permian (Volcanic rocks may, in part be Pennsylvanian) Maple Creek Gabbros intrusive contact Kluane Gabbro-Ultramafic Complexes _ intrusive contact _ Hasen Creek Formation Gabbro and ol ivine gabbros. Gabbro, o l iv ine gabbro, per ido t i te , and dunite. Shale, s i l t s t one , a r g i l l i t e , l imestone, greywacke, and conglomerate. Station Creek Formation Transit ion Zone - gradational contact zone consist ing of black shale, s i l t s t one , argi l laceous limestone, and tuf f . Basal t ic andesite f lows, tu f f s , agglomerates, and minor limestone and a r g i l l i t e . 14 uni t . V o l c a n i c f l ows a r e a p h a n i t i c t o f i n e - g r a i n e d , medium g r e e n , and l o c a l l y s c h i s t o s e . P i l l o w s , measuring 15 t o 30 cm by 30 to 60 cm i n the plane o f e x p o s u r e , a re p r e s e r v e d l o c a l l y and v e s i c l e s a re small (0.3 t o 1 mm) and s p a r s e . Main m i n e r a l c o n s t i t u e n t s o f t h e flows a r e p l a g i o c l a s e and a u g i t e w i t h a c c e s s o r y h o r n b l e n d e , m a g n e t i t e and i n t e r s t i t i a l q u a r t z . C e r t a i n flows a r e p o r p h y r i t i c w i t h p h e n o c r y s t s o f p l a g i o c l a s e , 2 t o 16 mm by 1 to 3 mm, i n a f i n e r - g r a i n e d d i a b a s i c m a t r i x . P l a g i o c l a s e has been almost c o m p l e t e l y s a u s s u r i t i z e d . The flows have been p r o p y l i t i z e d w i t h the f o r m a t i o n o f c a l c i t e , e p i d o t e and c h l o r i t e a f t e r a u g i t e and hornble n d e and as amygdules. T u f f s a r e f i n e - t o medium-grained and range t o l a p i l l i and l a p i l l i c r y s t a l t u f f . The t u f f s a r e massive t o t h i n l y bedded ( P l a t e 1) w i t h i n d i v i d u a l beds measuring 10 t o 20 cm t h i c k . Some o f t h e s e beds show s i z e and c o l o u r s o r t i n g from c o a r s e r - g r a i n e d and d a r k e r green m a t e r i a l to f i n e r - g r a i n e d and medium green t u f f . The f i n e t u f f grades i n t o l a p i l l i t u f f and c o a r s e r p y r o c l a s t i c s w i t h an i n c r e a s e i n s i z e and volume p e r c e n t o f s u b a n g u l a r t o subrounded c r y s t a l and rock fragments. S i z e and volume p e r c e n t o f fragments v a r y , r e s p e c t i v e l y , from 1 to 3 mm and up t o 10 p e r c e n t i n f i n e - t o medium-grained t u f f , g r e a t e r than 4 mm and 10 t o 20 p e r c e n t i n l a p i l l i t u f f , and g r e a t e r than 32 mm and 20 to 40 p e r c e n t i n a g g l o m e r a t e s . Massive t o p o o r l y bedded c o a r s e p y r o c l a s t i c r o c k s c o n s i s t o f pa l e to dark green fragments i n a medium gree n , f i n e -g r a i n e d m a t r i x ( P l a t e 2 ) . Fragments i n the agglomerate a re s u b a n g u l a r to subrounded and range i n s i z e from 15 t o 60 cm, a v e r a g i n g 20 cm a c r o s s . The p y r o c l a s t i c m a t r i x c o n s i s t s o f s a u s s u r i t i z e d p l a g i o c l a s e , 15 P l a t e 1. F i n e - to medium-grained t u f f a c e o u s b a s a l t i c a n d e s i t e forms a t h i c k s e c t i o n w i t h i n S t a t i o n Creek F o r m a t i o n . T h i s rock type may appear massive o r t h i n l y bedded as shown i n t h i s photograph taken o f an exposure a l o n g Burwash Creek. 16 P l a t e 2. V o l c a n i c b r e c c i a and agglomerate o f S t a t i o n Creek Formation a r e more a n d e s i t i c than u n d e r l y i n g t u f f s ( P l a t e 1 ) . Many o f t h e l a r g e r fragments i n t h i s photograph a r e 20 to 25 cm a c r o s s . G e n e r a l l y , fragments w i t h i n t h i s c o a r s e p y r o c l a s t i c rock are a p a l e r green to gr e y - g r e e n than i s t h e m a t r i x . The exposure i n t h i s photograph o c c u r s a l o n g Burwash Creek. 17 c l i n o p y r o x e n e , m a g n e t i t e , g l a s s y m a t e r i a l . , minor q u a r t z , and patches o f c h l o r i t e and c a l c i t e . In the t u f f s , c r y s t a l fragments i n c l u d e p l a g i o c l a s e , a u g i t e , h o r n b l e n d e , and r a r e l y , s e r p e n t i n e pseudomorphs a f t e r o l i v i n e . Rock fragments a r e t y p i c a l l y l a r g e r than c r y s t a l fragments and range from a p l a g i o c l a s e porphyry w i t h minor a u g i t e t o a p l a g i o c l a s e - a u g i t e d i a b a s e . A l t e r a t i o n has produced s e r i c i t e o r s a u s s u r i t e a f t e r p l a g i o c l a s e , and v a r y i n g amounts o f c a l c i t e , e p i d o t e , and c h l o r i t e a f t e r a u g i t e and h o r n b l e n d e . Whole rock a n a l y s e s o f S t a t i o n Creek v o l c a n i c rocks ( T a b l e 2) show a c o n s i d e r a b l e range; flows tend t o be b a s a l t i c and p y r o c l a s t i c s more a n d e s i t i c . Both are d i o p s i d e and h y p e r s t h e n e - n o r m a t i v e . Flows show normative o l i v i n e , whereas p y r o c l a s t i c r o c k s a r e t y p i c a l l y q u a r t z - n o r m a t i v e . Trace element amounts a r e h i g h l y v a r i a b l e ( T a b l e 2 ) , a l t h o u g h Cu and Zn tend t o be h i g h e s t i n the f i n e p y r o c l a s t i c r o c k s . Both Co and Cr d e c r e a s e from f l o w s t o t u f f s t o a g g l o m e r a t e s . C o r r e l a t i o n s between metals and s u l f u r a r e poor, s u g g e s t i n g most o f t h e metal c o n t e n t i s i n the s i l i c a t e s . Agreement i s g e n e r a l l y good between whole rock a n a l y s e s o f t h e s e S t a t i o n Creek r o c k s and a n a l y s e s o f b a s a l t i c a n d e s i t e s i n i s l a n d a r c e n v i r o n m e n t s . T a b l e 3 l i s t s two conodont d e t e r m i n a t i o n s from l i m e s t o n e beds w i t h i n S t a t i o n Creek v o l c a n i c r o c k s . The m i c r o f a u n a i n d i c a t e a Late M i s s i s s i p p i a n t o Lower Permian ( L e o n a r d i a n ) age (B.E.B. Cameron, w r i t t e n comm., 1977). These r e s u l t s a r e i n agreement w i t h those o f M u l l e r (1967) arid Read and Monger (1976). Upper 400 m o f S t a t i o n Creek Formation i s c h a r a c t e r i z e d by i n t e r -bedded b l a c k s h a l e , s i l t s t o n e , a r g i l l a c e o u s l i m e s t o n e , and c h e r t y a r g i l l i t e . I n t e r c a l a t i o n s o f v e r y f i n e - g r a i n e d t u f f a r e numerous, but d e c r e a s e 18 Table 2. Whole Rock Chemistry, CIPW Norms, and Trace Element Data for Station Creek Formation^ AGGLOMERATE TUFF FLOW Oxi de 102-1 219-1 1181-B 86-1 146-1 1139-3 PI 046 P1006 P1016 P1048A P1049 Si0 2 55 .5 55 .5 48, .5 56.5 50. ,0 53.0 50. ,0 49. .5 52 .5 49.5 Ti0 2 .61 ,62 .79 .87 ,50 .61 2. ,01 1 .56 .47 .89 A 1 2 ° 3 16 .6 14, ,0 15 .5 14.9 13 .9 14.8 12. ,9 13 .3 13 .5 14.4 8 .0 7. .8 13 .2 9.6 11. .3 10.7 13 .6 12 .0 10 .6 14.2 MnO .14 .20 .16 .17 .16 .16 .18 .10 .18 .20 MgO 4 .0 4 .8 6 .5 3.7 8. .2 9.2 7. .2 7, .5 g .3 7.0 CaO 5 .8 3. 7, .4 3.8 10 .7 2.7 9 .2 7 .6 6. .0 9.7 Na20 4 .0 3. .5 1. 4 4.9 3, .4 5.0 .62 4, .7 4 . 5 3.1 K20 1. .0 2. .6 1 .8 1.4 .67 .48 .28 .35 .29 .94 P2°5 .79 47 .69 .61 17 .33 .43 .50 .30 .47 L.O.I. 3 .4 6. 1 4. .2 2.5 1. ,8 4.1 3, , g 3. .8 4. . 1 1.9 S .1 .1 1 .5 .1 .0 .2 .0 .1 .0 TOTAL: 99. 94 99. 59 100. .24 99.45 100. 90 101.08 100. .52 100. 91 101. ,94 102.30 Qtz. 11, .56 10 .54 7, .6 9.28 1. .31 17.28 Orth. 5. .94 16 .68 11 .26 8.35 4 .0 2. .94 1.72 2. 12 1.74 5 .58 Al bi te 34, .88 31. .55 12 .72 43.54 29 .45 43 .74 5.51 41, .3 39.96 26. .61 Anor. 24. .54 15 .99 31 .93 15.13 20 .91 11 .6 32.82 14. 54 15.78 22. .51 Di op. 1 .44 1 .32 .19 25 .35 9.48 16, .78 10.32 18. 22 Hyper. 13, .97 15 .88 22, .7 13.65 3. .79 28. .98 18.68 5. .52 20.88 13. .88 Mgt. 5, .56 5 .58 9, .22 6.66 7 .63 7. .42 9.48 8. .3 7.28 9. .5 Apa. ' 1. .91. 1. .17 1, .67 1.47 .39 .78 1.04 1. .2 .71 1. .09 11 men. 1. .2 1 .26 1, .58 1.72 .96 1 .21 3.99 3. .06 .92 1. .7 Oliv. 7. .53 7. 17 2.4 91 Neph. Corun. 43 2. .02 Mg/(Mg+Fe) in Silicates 78. .3 81. .5 77. 7 74.8 82. .9 85. .6 84.4 85. 7 85.2 77. .6 Cu 0 40 40 145 131 0 70 10 20 140 Ni 10 40 1 5 106 79 71 59 208 41 Co 28 32 32 34 41 44 43 42 42 44 Cr 110 230 130 120 370 330 270 260 750 190 Zn 63 83 89 932 87 84 105 70 63 93 Ba 141 642 69 675 143 238 25 73 30 214 Sr 529 277 279 360 290 65 399 306 215 164 Rb 20 63 3 18 5 8 2 2 1 10 Nb .9 6 10 5 3 4 12 11 5 5 Zr 89 95 107 96 45 33 127 117 36 48 Y 20 20 28 24 16 14 27 23 17 26 1 Sample descriptions in Appendix A2. 2 As Fe203 19 TABLE 3. Microfauna from Insoluble Limestone Residues 1 MAP UNIT SAMPLE G.S.C. LOCALITY DETERMINATIONS AGE Station Creek 29-4 2 Formation Hasen Creek Formation 221-1 1037-1,-3 P1017 P1090A.E 126-1 1148 1153 95304 95312 95313 95318 95319 Productid brachiopod spines, f i sh teeth and sca les , abundant f i sh debris. Conodonts: few blade fragments (hindeodell id) Neogondolella sp. (poor preservation) Neostreptognathodus su lcopl icatus. Rare indeterminate conodont fragments Crinoid columnals, skeletal debris (cora l l ine & bryozoan),Productid brachiopod spines, Nodosarid?, foramini fer , gastropods, brachiopod fragments, f i sh teeth. Conodonts: Adetagnathus sp. One possible conodont fragment. Fish? fragment. Lower Permian (Leonardian) Indeterminate Late Mississippian to Early Permian Indeterminate Indeterminate 95309 Trace of skeletal mater ia l . 95315 One possible f ish(?) fragment. 95317 Two spines (possibly Productid brachiopod spines). Indeterminate Indeterminate Indeterminate (?Devonian to Permian). Nikolai Greenstone 130-1 131-1 95310 Coral debr is , skeletal debris (bryozoan), foraminifera (nodosarid), gastropods, rad io la r ian , f i sh tooth, Late Tr iass ic (recrystalVized conodont?). (Early Norian) Conodonts: Epigondolel1 a abneptis Epigondolella p r im i t i a . 95311 Skeletal debr is(?) . Indeterminate 1 Data from Geological Survey of Canada: Report No. 6 - BEBC-77 (B.E.B. camaron, Written comm., 1977) 2 Sample numbers for rocks col lected during th is study. 20 i n abundance upwards. T h i s s e c t i o n o f S t a t i o n Creek i s h e r e i n c a l l e d the T r a n s i t i o n Zone and forms a g r a d a t i o n a l c o n t a c t w i t h o v e r l y i n g Hasen Creek r o c k s . The top o f S t a t i o n Creek Formation i s taken a t the f i n a l d i s a p p e a r a n c e o f t u f f a c e o u s m a t e r i a l w i t h i n the T r a n s i t i o n Zone. D e p o s i t i o n o f S t a t i o n Creek Formation v o l c a n i c r o c k s was subaqueous, as e v i d e n c e d by p i l l o w s t r u c t u r e s w i t h s p a r s e v e s i c l e c o n t e n t , massive t o t h i n l y bedded t u f f s w i t h i n t e r l a y e r e d s i l t s t o n e and s h a l e , and i n t e r b e d d e d l i m e s t o n e u n i t s w i t h i n both the t u f f a c e o u s and.flow s e c t i o n s . The o r g a n i c - r i c h n a t u r e o f t h e s h a l e s and a r g i l l a c e o u s c o n t e n t o f l i m e s t o n e beds w i t h i n the T r a n s i t i o n Zone s u g g e s t a r e s t r i c t e d b a s i n e nvironment o f d e p o s i t i o n . Hasen Creek Formation Hasen Creek s e d i m e n t a r y sequence i s a p p r o x i m a t e l y 900 m t h i c k . I t c o n s i s t s o f g r e y t o b l a c k s h a l e , c h e r t y a r g i l l i t e and c h e r t , and s i l t s t o n e i n the l o w e r p o r t i o n w i t h an upward change t o s h a l y l i m e s t o n e , b u f f -c o l o r e d massive l i m e s t o n e , and d i s c o n t i n u o u s beds o f reddish-brown c o n g l o m e r a t e , massive greywacke, and sandstone (see P l a t e s 3 and 4 ) . Hasen Creek Formation i s commonly f a u l t - b o u n d e d a t the T r a n s i t i o n Zone and i n t h e Swede Johnson Creek and Q u i l l Creek a r e a s the s e d i m e n t a r y sequence i s l o c a l l y m i s s i n g . Upper c o n t a c t o f t h i s u n i t i s an e r o s i o n a l s u r f a c e o v e r l a i n by Upper T r i a s s i c b a s a l t f l o w s . V a r i o u s p a r t i a l s e c t i o n s through Hasen Creek Formation i n the Q u i l l Creek a r e a are shown s c h e m a t i c a l l y i n F i g u r e 3. The s h a l e i n t h i s s e d i m e n t a r y sequence i s g e n e r a l l y b l a c k and l o c a l l y grades t o s l a t e . P y r i t e c r y s t a l s a r e common and o x i d a t i o n g i v e s exposures a r u s t y a ppearance. S h a l e and s i l t s t o n e are commonly i n t e r b e d d e d , w i t h 21 P l a t e 3 . Pale green to g r e y - w h i t e c h e r t y a r g i l l i t e and a r g i l l i t e a re prominent rock types w i t h i n Hasen Creek Formation. The a r g i l l i t e v a r i e s from massive t o t h i n l y bedded. T h i s w e l l l a y e r e d , f o l d e d rock i s exposed a l o n g Burwash Creek. C i r c l e d i s a g e o l o g i c hammer used t o denote s c a l e . 22 Plate 4. Shale and s i l t s tone are typ ica l consti tuents in lower parts of the Hasen Creek sedimentary sequence. These rock types are general ly well f o l i a ted to highly deformed and contain numerous minor folds with or ientat ions s im i l a r to those of larger scale folds in the Qu i l l Creek area. This photograph was taken along the Qu i l l Creek road, which leads to Wellgreen Mine. To denote sca le , the tree i s about 3 m high. A B C D E F i g u r e 3 . Schematic s t r a t i g r a p h i c s e c t i o n s through Hasen Creek F o r m a t i o n . Some o f the s e c t i o n s a r e p a r t i a l due to f a u l t i n g ( S e c t i o n B) or e r o s i o n . The base o f S e c t i o n s . A, C, D, and E i s i n s t r a t i g r a p h i c c o n t a c t w i t h the T r a n s i t i o n Zone. Probable c o r r e l a t i o n s are i n d i c a t e d by dashed l i n e s between s e c t i o n s . The s e c -t i o n s a r e l o c a t e d as f o l l o w s : A i s a t the nose o f the s y n c l i n e between Donjek R i v e r and Q u i l l Creek; B i s n o r t h w e s t o f Well green Mine; C i s n o r t h e a s t o f Well green Mine; D i s s o u t h e a s t o f L i n d a Creek; and E i s about midway between Q u i l l and Burwash Creeks. 24 i n d i v i d u a l l a m i n a a v e r a g i n g 0.5 t o 1 cm i n t h i c k n e s s . C h e r t and c h e r t y a r g i l l i t e a r e c h a r a c t e r i s t i c a l l y v e r y p a l e g r e y - g r e e n t o p a l e grey and t h i n l y banded (0.5 cm t h i c k o r l e s s ) . Limy a r g i l l i t e i s l o c a l l y i n t e r b a n d e d . Limestones may be g r e y , f i n e - g r a i n e d , and a r g i l l a c e o u s o r b u f f - c o l o r e d , f i n e - g r a i n e d , and massive w i t h c h e r t bands and l e n s e s o r w h i t e t o b u f f , medium-grained, and c r y s t a l l i n e . Hasen Creek conglomerates and p e b b l y greywackes a r e d i r t y , reddish-brown t o g r e y -brown, and c o n t a i n numerous c h e r t , a r g i l l i t e , and some s h a l e pebbles and c o b b l e s . Minor i n t e r b e d d e d sandstone i s brown to grey-brown and massive. F o s s i l c o n t e n t o f t h i s s e d i m e n t a r y sequence i s p r e s e n t e d i n T a b l e 3 and i n d i c a t e s a Lower Permian age, i n agreement w i t h r e s u l t s by M u l l e r (1967) and Read and Monger (1976). The s e d i m e n t a r y rock assemblage and i n t e r l a y e r i n g o f s h a l e s , greywackes, and t h r e e d i s t i n c t l i m e s t o n e u n i t s i n Hasen Creek Formation s u g g e s t d e p o s i t i o n i n a sub-aqueous b a s i n under c o n s i d e r a b l e f l u c t u a t i o n i n water d e p t h . N i k o l a i Greenstone The N i k o l a i Greenstone i s a sequence o f v o l c a n i c f l o w s , w i t h minor i n t e r b e d d e d l i m e s t o n e , which d i s c o n f o r m a b l y o v e r l i e s Hasen Creek Formation. T h i s u n i t i s 900 m t h i c k i n the Q u i l l Creek a r e a , but reaches 1000 m e l s e w h e r e i n the Kluane Ranges (Read and Monger, 1976) and l o c a l l y , exceeds 1200 m i n e a s t e r n A l a s k a (MacKevett, 1971). At t h e base o f the v o l c a n i c p i l e i s a t h i n , d i s c o n t i n u o u s maroon t o dark green v o l c a n i c b r e c c i a and p i l l o w b r e c c i a (Read and Monger, 1976) t h a t reaches a maximum o f 100 m i n t h i c k n e s s i n the Kluane Ranges. N i k o l a i flows a r e t h i n , v e s i c u l a r t o a m y g d a l o i d a l , and s i m i l a r t h r o u g h o u t the v o l c a n i c p i l e . Flows average 5 t o 15 m t h i c k and commonly f l o w tops a r e g e n t l y u n d u l a t i n g and r e d d i s h - p u r p l e due t o e x t e n s i v e 25 hematite ( P l a t e 5 ) . Lower p a r t s o f t h e flows a r e dark green. Amygdules, 1 t o 5 mm i n d i a m e t e r , are c h a r a c t e r i s t i c o f N i k o l a i v o l c a n i c r o c k s and make up an average o f 10 t o 30 p e r c e n t by volume. They are s c a t t e r e d t h r o u g h o u t the f l o w s , a l t h o u g h t h e r e i s a tendency f o r amygdule s i z e to i n c r e a s e upward and f o r a s l i g h t c o n c e n t r a t i o n o f amygdules i n the c e n t r a l p o r t i o n o f each f l o w ( P l a t e 6 ) . D i s c o n t i n u o u s , t h i n l y bedded (up t o 30 m t h i c k ) b i o c l a s t i c l i m e s t o n e and g r e e n i s h - g r e y s h a l e are i n t e r b e d d e d w i t h N i k o l a i flows i n the lower h a l f o f the u n i t . C o n t a c t s a r e s h a r p and s t r a t i g r a p h i c . N i k o l a i Greenstone i s p e t r o g r a p h i c a l l y d i v i d e d i n t o : (1) f i n e d i a b a s i c - t e x t u r e d f l o w s ; (2) p o r p h y r i t i c t o g l o m e r o p o r p h y r i t i c flows w i t h o r w i t h o u t amygdules; and (3) v e r y f i n e - g r a i n e d a m y g d a l o i d a l l a v a f l o w s . M i n e r a l c o n s t i t u e n t s i n c l u d e p l a g i o c l a s e ( l a b r a d o r i t e ) , a u g i t e , m a g n e t i t e , h e m a t i t e , and g l a s s y m a t e r i a l . P h e n o c r y s t s i n c l u d e s a u s s u r -i t i z e d p l a g i o c l a s e , p a r t l y a l t e r e d a u g i t e , and minor s e r p e n t i n e pseudomorphs a f t e r o l i v i n e . A l t e r a t i o n has produced numerous c a l c i t e and c h l o r i t e patches w i t h i n t h e groundmass. Amygdules c o n s i s t o f one o r more o f c h l o r i t e , q u a r t z , e p i d o t e , c a l c i t e , l a u m o n t i t e , and p r e h n i t e . In g e n e r a l , the g r e a t e r t h e volume p e r c e n t o f amygdules i n a f l o w , the more v a r i e d i s the m i n e r a l o g y o f t h e v e s i c l e f i l l i n g s . Whole rock and t r a c e element a n a l y s e s f o r N i k o l a i Greenstone are g i v e n i n T a b l e 4. The c h e m i s t r y i s i n t e r m e d i a t e between t h a t o f o c e a n i c t h o l e i i t e s and b a s a l t i c k o m a t i i t e s (see C h a p t e r 4 ) . N i k o l a i b a s a l t s a r e o l i v i n e - n o r m a t i v e . Conodonts from a l i m e s t o n e bed w i t h i n the N i k o l a i ( T a b l e 3) i n d i c a t e an Upper T r i a s s i c ( E a r l y N o r i a n ) age (B.E.B. Cameron, w r i t t e n comm., 1977). T h i s agrees w i t h d e t e r m i n a t i o n s by M u l l e r (1967), Read 26 P l a t e 5. B a s a l t flows o f t h e N i k o l a i Greenstone a r e commonly 5 t o 15 m t h i c k . Lower p a r t s o f t h e flows a r e g e n e r a l l y dark g r e e n , whereas upper p a r t s are r e d d i s h - p u r p l e due t o an abundance o f h e m a t i t e . Flow s u r f a c e s , a p p a r e n t here as a c o l o r change (green t o red-brown), are g e n t l y u n d u l a t i n g . T h i s exposure o c c u r s a l o n g Burwash Creek. 2 7 Plate 6 . Nikola i basalts are cha rac te r i s t i ca l l y atnygdaloidal and indiv idual flows may show a concentration of amygdules toward the i r centers. Amygdule s ize general ly increases upwards within a s ingle flow. This exposure occurs along the creek located south of Arch Creek va l ley and opposite to the Arch Creek property. 28 T a b l e 4 . W h o l e R o c k C h e m i s t r y . C IPW N o r m s , a n d T r a c e E l e m e n t D a t a f o r N i k o l a i G r e e n s t o n e ' ' N I K O L A ! FLOWS O x i de 5 5 - •1 1 1 4 - 1 1 5 0 - 1 1 8 2 - 1 1 0 4 5 - 1 1 0 4 5 - 2 1 0 4 5 - 5 A 1 0 4 5 - 5 B 1 0 4 5 - 6 1 1 4 0 - 4 S i 0 2 4 5 . .5 4 5 . 5 4 6 . 5 4 6 . 5 4 5 . 0 4 7 . 5 4 9 . 0 4 6 . 5 T i Q 2 1. 35 . 7 1 1 . 0 7 . 7 5 1 . 2 3 1 . 2 2 1 . 3 2 1 . 5 2 A 1 2 0 3 1 4 . .6 1 4 . 7 1 5 . 7 1 6 . 5 1 5 . 3 1 5 . 3 1 2 . 8 1 2 . 5 F e T 2 1 1 . 6 1 1 . 5 1 0 . 8 1 2 . 3 1 2 . 3 1 0 . 3 1 2 . 5 1 2 . 6 MnO .14 . 1 4 . 1 4 . 1 4 . 1 4 . 1 4 . 1 7 . 1 6 MoO 6 . 0 6 . 6 8 . 0 8 . 5 7 . 8 8 . 0 6 . 7 6 . 3 CaO 1 0 . .6 1 1 . 0 5 . 4 5 . 0 6 . 7 9 . 0 9 . 3 9 . 5 N a 2 0 4 . . 3 4 . 1 2 . 4 2 . 8 4 . 0 3 . 3 2 . 9 3 . 2 K 2 0 4 7 . 3 1 3 . 3 2 . 7 . 3 2 . 3 4 . 5 6 . 9 P 2 ° 5 3 3 . 4 7 . 1 7 . 4 8 . 3 3 . 3 6 . 3 3 . 5 3 L . O . I . 4 . . 8 4 . 4 6 . 0 4 . 9 5 . 0 4 . 2 3 . 5 5 . 0 S 0 . 0 .1 . 0 .1 . 3 . 0 . 0 T O T A L : 9 9 . . 6 9 9 9 . 4 3 9 9 . 5 8 1 0 0 . 5 7 9 8 . 2 2 9 9 . 9 6 9 9 . 0 8 9 8 . 7 1 Q t z . 3 . 4 2 O r t h . 2 . 9 3 1 . 9 1 2 0 . 9 1 6 . 5 8 2 . 0 7 2 . 1 4 3 . 4 8 5 . 7 2 A l b i t e 2 6 . 0 7 2 5 . 3 3 2 2 . 2 2 2 4 . 5 9 3 6 . 5 7 2 9 . 7 9 2 5 . 7 9 2 9 . 3 2 A n o r . 2 0 . . 3 1 2 2 . 0 4 2 3 . 8 2 3 . 0 7 2 4 . 7 7 2 7 . 0 4 2 1 . 4 5 1 8 . 3 D i o p . 2 6 . 5 7 2 6 . 1 7 3 . 2 6 6 . 9 1 3 . 8 5 1 9 . 8 8 2 2 . 9 9 H y p e r . 6 . 3 1 0 . 6 8 2 . 8 9 1 1 . 5 4 1 4 . 8 7 8 . 5 3 M g t . 7 . . 1 5 7 . 0 4 6 . 7 4 7 . 5 7 . 7 6 . 3 7 . 6 5 7 . 8 6 A p a . . 8 2 1 . 1 5 . 4 2 1 . 1 6 . 8 3 . 8 9 . 8 1 . 3 2 11 m e n . 2 . . 7 2 1 . 4 2 2 . 1 9 1 . 5 2 . 5 2 2 . 4 4 2 . 6 4 3 . 1 O l i v . 6 . 7 2 8 . 7 1 4 . 1 8 1 3 . 8 5 1 5 . 7 4 6 . 0 1 2 . 8 6 . / ' N e p h . 6 . . 7 1 6 . 2 3 C o r u n . 1 . 0 6 M g / ( M g + F e ) 76 . 8 7 5 . 7 8 1 . 7 7 9 . 0 7 9 . 5 8 3 . 3 7 6 . 5 7 6 . 2 I n S i l i c a t e s C u 8 0 3 2 , 0 0 0 9 8 0 2 0 1 1 5 8 0 4 0 50 6 0 8 0 N i 6 3 8 5 7 1 0 8 76 6 4 74 7 3 74 4 8 Co 4 7 3 8 4 6 44 4 3 4 3 4 8 4 2 4 1 33 -C r 2 7 0 2 0 0 2 2 0 3 7 0 3 7 0 2 9 0 3 0 0 2 7 0 3 5 0 2 8 0 Zn 71 2 7 5 2 6 1 71 6 0 8 5 7 7 1 0 2 85 B a 7 8 6 12 72 1 1 3 1 8 8 12 21 36 1 9 2 S r 1 5 6 3 3 4 0 1 4 5 1 0 2 1 9 6 1 0 2 1 7 7 1 4 2 4 6 1 Rb 4 1 1 4 4 1 2 5 1 2 6 15 Nb 8 6 11 5 7 5 8 9 9 13 Z r 8 9 3 6 3 9 37 7 8 4 2 8 2 82 9 7 1 3 4 Y 24 17 17 1 7 2 2 1 8 2 3 2 2 24 31 1 S a m p l e d e s c r i p t i o n s i n A p p e n d i x A 2 2 A s F e 2 0 3 29 and Monger (1976), and MacKevett (1971). The h e m a t i t i c n a t u r e o f most o f t h e N i k o l a i f l o w t o p s , abundance o f v e s i c l e s , and presence o f i n t e r b e d d e d l i m e s t o n e o n l y i n the lower p a r t o f t h e v o l c a n i c p i l e are e v i d e n c e o f a l a r g e l y s u b a e r i a l e n v i r o n -ment o f d e p o s i t i o n f o r t h e s e v o l c a n i c r o c k s . C h e m i c a l l y , t h e y f a l l i n a c l a s s o f i n t e r m e d i a t e b a s a l t s , h a v i n g both t h o l e i i t i c and b a s a l t i c k o m a t i i t i c c h a r a c t e r i s t i c s (see N a l d r e t t and T u r n e r , 1977). I n t r u s i v e Rocks Kluane g a b b r o - u l t r a m a f i c complexes a r e s i l l - o r s h e e t - l i k e i n t r u s i o n s t h a t l i e comformably a l o n g two s t r a t i g r a p h i c l e v e l s i n the Lower Permian sequence. Dominantly p e r i d o t i t i c t o d u n i t i c b o d i e s (Lower Group complexes) i n t r u d e the T r a n s i t i o n Zone o f S t a t i o n Creek F o r m a t i o n , whereas p e r i d o t i t e - g a b b r o complexes (Upper Group complexes) i n t r u d e Hasen Creek s e d i m e n t a r y sequence. C o n t a c t s o f t h e complexes a r e g e n e r a l l y s h e a r e d , but remnants o f i n t r u s i v e c o n t a c t s ( P l a t e 7) and thermal a u r e o l e s i n w a l l r o c k are p r e s e r v e d l o c a l l y . L a r g e r complexes c o n t a i n h o r n f e l s e d x e n o l i t h s o f nearby c o u n t r y rock ( P l a t e 8 ) . Lower Group complexes have d u n i t e a t t h e base and p e r i d o t i t e above. Minor o l i v i n e gabbro forms a t h i n b o r d e r phase o f the u l t r a m a f i c i n t r u s i o n s . L a y e r i n g i n t h e Lower Group complexes cannot be seen i n t h e f i e l d , but i s r e v e a l e d by p e t r o g r a p h i c work, which shows z o n i n g from both c o n t a c t s inwards o f o l i v i n e gabbro t o w e h r i i t e t o I h e r z o l i t e . Upper Group complexes c o n s i s t o f gabbro s t r u c t u r a l l y above p e r i d o t i t e i n the r a t i o 1:2, r e s p e c t i v e l y . A g a i n , l a y e r i n g i n t h e p e r i d o t i t e i s not v i s i b l e i n the f i e l d , but p e t r o g r a p h i c work shows an upward change from I h e r z o l i t e to w e h r i i t e . M i n e r a l c o n s i s t u e n t s i n the u l t r a m a f i c r o c k s a r e o l i v i n e (Fo 83-86), e n s t a t i t e , a u g i t e , m a g n e t i t e , p l a g i o c l a s e , s u l p h i d e s , minor 30 P l a t e 7. A l t h o u g h s h e a r e d c o n t a c t s predominate f o r the Kluane complexes, o c c a s i o n a l l y s h a r p c o n t a c t s , as shown here ( j u s t above the hammer handle) between an u l t r a m a f i t e s t r i n g e r and w a l l r o c k , can be found a d j a c e n t t o the complex. T h i s photograph was taken on P i c k h a n d l e p r o p e r t y and t h e u l t r a m a f i c body may r e p r e s e n t p a r t o f a d i g i t a t e d s o u t h e a s t end o f the Canalask complex. 31 P l a t e 8. X e n o l i t h s o f b a s a l t i c a n d e s i t e t u f f , metamorphosed t o an assemblage o f c l i n o p y r o x e n e and p l a g i o c l a s e , are found w i t h i n the lower p a r t s o f Kluane complexes, e s p e c i a l l y the A r c h Creek complex and Q u i l l Creek complex (shown h e r e ) . C o n t a c t s o f the x e n o l i t h s a r e commonly s h a r p , a l t h o u g h p a r t s o f i n c l u s i o n s may show more g r a d a t i o n a l o r hazy c o n t a c t s w i t h the u l t r a m a f i c r o c k . Both types o f c o n t a c t s a r e v i s i b l e i n t h i s p h o t o g r a p h , which was taken a l o n g L i n d a Creek. 32 p h i o g o p i t i c b i o t i t e , and h o r n b l e n d e . The o l i v i n e gabbro b o r d e r phase c o n t a i n s 30 t o 45 p e r c e n t o l i v i n e a l o n g w i t h a u g i t e , h y p e r s t h e n e , p l a g i o -c l a s e , m a g n e t i t e , and s u l p h i d e s . Gabbro i n Upper Group complexes c o n s i s t s o f a u g i t e , p l a g i o c l a s e , minor o l i v i n e and h y p e r s t h e n e , and t r a c e amounts o f m a g n e t i t e and s u l p h i d e s . A l l u l t r a m a f i c r o c k s have been s t r o n g l y s e r p e n t i n i z e d . A l t e r a t i o n has produced t r e m o l i t e - a c t i n o l i t e a f t e r pyroxenes and e p i d o t e and h y d r o g r o s s u l a r i t e a f t e r p l a g i o c l a s e . G a b b r o i c r o c k s c o n t a i n p a r t l y a l t e r e d pyroxenes and s a u s s u r i t i z e d p l a g i o c l a s e . C h e m i c a l l y , Kluane g a b b r o - u l t r a m a f i c complexes show low T n ^ f o r a g i v e n MgO, low Fe/Mg r a t i o s f o r a g i v e n A^O^, and h i g h MgO, N i , and Cr ( C h a p t e r 3 ) . The c o m p o s i t i o n s o f Kluane complexes f a l l w i t h i n o r v e r y c l o s e t o the f i e l d s f o r k o m a t i i t i c r o c k s ( A r n d t , 1977; A r n d t e t a l _ . , 1977; N a l d r e t t and C a b r i , 1976; N a l d r e t t and T u r n e r , 1977; N a l d r e t t and Goodwin, 1977). Primary p h l o g o p i t i c b i o t i t e y i e l d e d a potassium-argon age date o f 224+8 Ma (Lower T r i a s s i c 1 ) . The i n t r u s i v e c h a r a c t e r o f t h e s e complexes and t h e i r " p r i m i t i v e " c h e m i s t r y s u g g e s t s they were d e r i v e d from the upper mantle as p a r t i a l m e lt d i a p i r s . The bulk c o m p o s i t i o n o f the Q u i l l Creek complex i s remarkably s i m i l a r t o t h a t o f upper mantle p y r o l i t e (see C h a p t e r 3 ) . Maple Creek gabbros, p r e v i o u s l y unnamed, o c c u r t h r o u g h o u t S t a t i o n Creek and Hasen Creek Formations and N i k o l a i G r e e n s t o n e . These dykes and s i l l s a r e g e n e r a l l y l e s s than 50 m wide, a l t h o u g h one dyke w i t h i n the N i k o l a i measures 580 m by 120 m i n s u r f a c e exposure. The gabbros a r e g r e e n i s h - b r o w n , medium-grained, and d i a b a s i c and c o n s i s t o f a u g i t e and p l a g i o c l a s e w i t h minor o l i v i n e , o r t h o p y r o x e n e , h o r n b l e n d e , and m a g n e t i t e . A l t e r a t i o n has produced s a u s s u r i t e and t r e m o l i t e - a c t i n o l i t e 1 A c c o r d i n g t o G e o l o g i c a l Time T a b l e , c o m p i l e d by F.W.B. Van E y s i n g a , 3rd Ed., 1975, E l s e v i e r S c i e n t i f i c P u b l i s h i n g Company, Amsterdam. 33 w i t h t r a c e s o f s e r p e n t i n e , c h l o r i t e , c a l c i t e , and e p i d o t e . CIPW norms from whole rock a n a l y s e s show t h a t the Maple Creek gabbros a r e o l i v i n e t h o l e i i t e s g e n e r a l l y , but a l t h o u g h TiCX, i s s l i g h t l y h i g h , most can a l s o be c l a s s i f i e d as b a s a l t i c k o m a t i i t e s . F i e l d e v i d e n c e s u p p o r t s an Upper T r i a s s i c age f o r t h e s e Maple Creek gabbros. S i n c e these g a b b r o i c dykes and s i l l s i n t r u d e a l l Permian r o c k s , the Q u i l l Creek complex (see C h a p t e r 3 ) , and p e n e t r a t e i n t o the N i k o l a i Green-s t o n e they may w e l l r e p r e s e n t remnants o f a f e e d e r system f o r the b a s a l t i c f l o w s . G r a n i t i c i n t r u s i o n s i n the Q u i l l Creek a r e a are l i m i t e d t o exposures a l o n g Burwash Creek. They i n c l u d e g r e y , medium-grained, massive horn-blende g r a n o d i o r i t e and w h i t e , crumbly, p o r p h y r i t i c q u a r t z l a t i t e . The g r a n o d i o r i t e belongs to the Kluane Range i n t r u s i o n s o f M u l l e r (1967). These i n t r u s i o n s form l a r g e p l u t o n s and b a t h o l i t h s i n the n o r t h e r n p a r t o f the Kluane Ranges and c o n t i n u e i n t o E a s t e r n A l a s k a where they have been d a t e d as C r e t a c e o u s ( R i c h t e r et_ a l _ . , 1975). The p o r p h y r i t i c q u a r t z l a t i t e a l o n g Burwash Creek i s T e r t i a r y ( C h r i s t o p h e r ejt a l _ . , 1972) and belongs t o M u l l e r ' s T e r t i a r y f e l s i t e s . C o n t a c t s o f t h i s l a t i t e appear conformable t o s u r r o u n d i n g Permian s t r a t i g r a p h y , however, exposures were o f l i m i t e d e x t e n t on e i t h e r s i d e o f the c r e e k and c o u l d not be t r a c e d any s i g n i f i c a n t d i s t a n c e . S t r u c t u r e and Metamorphism The Q u i l l Creek map ( F i g u r e 2) shows t h r e e prominent s t r u c t u r a l f e a t u r e s : two s u b p a r a l l e l s y n c l i n e s ; numerous major n o r t h w e s t - t r e n d i n g f a u l t s ; and s h o r t n o r t h e a s t - t r e n d i n g f a u l t s . The northwest s t r u c t u r a l p a t t e r n i s a l s o prominent i n the l a r g e r Kluane-Donjek Ranges a r e a (Read and Monger, 1976). 34 The e n t i r e P e r m o - T r i a s s i c sequence o f Q u i l l Creek a r e a has been f o l d e d and f a u l t e d . The f o l d s a r e i n c l i n e d and t i g h t t o i s o c l i n a l and data y i e l d a x i a l p l a n e s s t r i k i n g 110° and d i p p i n g 60° t o 70° southwest. F o l d axes v a r y from h o r i z o n t a l t o doubly p l u n g i n g w i t h plunges o f 10° to 30° and azimuths o f 112° and 280° ( T a b l e 5 ) . A x i a l t r a c e s o f the f o l d s a r e a t a 30° a n g l e t o t h e Shakwak F a u l t . Minor f o l d s a r e p r e s e n t i n Hasen Creek Formation s h a l e s and c h e r t y a r g i l l i t e s . O r i e n t a t i o n s o f some o f these f o l d s complement the major f o l d s , however, o t h e r minor f o l d s , c r e n u l a t i o n s on f o l i a t i o n s u r f a c e s , and c u l m i n a t i o n s and d e p r e s s i o n s o f the l a r g e i s o c l i n a l f o l d s i n d i c a t e a much l e s s prominent second phase o f f o l d i n g . F a u l t i n g has been i n t e n s e w i t h many l i t h o l o g i c c o n t a c t s a c t i n g as f a u l t s u r f a c e s o r major s h e a r z o n e s . Near v e r t i c a l d i p - s l i p f a u l t s a re p a r a l l e l t o t h e l a r g e f o l d a x i a l t r a c e s . Arch Creek v a l l e y i s bounded by two d i p - s l i p f a u l t s t h a t c r e a t e a graben w i t h N i k o l a i b a s a l t s i n the c e n t e r bounded by S t a t i o n Creek t u f f s . A n o t h e r major n o r t h w e s t -t r e n d i n g d i p - s l i p f a u l t runs a l o n g Tatamagouche Creek v a l l e y and forms the c o n t a c t between a g a b b r o - u l t r a m a f i c complex and t h e N i k o l a i Greenstone. A younger group o f n o r t h e a s t - t r e n d i n g minor f a u l t s l i e r o u g h l y p e r p e n d i c u l a r t o Shakwak Trench and o c c u r a l o n g d e e p l y i n c i s e d c r e e k s , such as Swede Johnson Creek, t h a t d r a i n i n t o t h e T r e n c h . The most prominent n o r t h e a s t - t r e n d i n g f a u l t o c c u r s a l o n g Q u i l l Creek v a l l e y and o f f s e t s a l a r g e g a b b r o - u l t r a m a f i c complex and rock u n i t s w i t h i n a n o r t h w e s t - t r e n d i n g s y n c l i n e . The type o f movement on thes e younger f a u l t s i s u n c e r t a i n . Low grade r e g i o n a l metamorphism has a f f e c t e d a l l r o c k s i n the Q u i l l Creek a r e a . C h l o r i t e s c h i s t i s found i n S t a t i o n Creek F o r m a t i o n , s l a t e s , p h y l l i t e s , and minor s c h i s t s a r e p r e s e n t i n Hasen Creek 35 T a b l e 5. A x i a l Plane and A x i s D e t e r m i n a t i o n s from S t e r e o n e t P l o t s o f Data f o r F o l d s i n Q u i l l Creek and P i c k h a n d l e Lake A r e a . FOLD AXIAL PLANE AXIS Q u i l l Creek S y n c l i n e 100°/71°SW 30°/112° (Northwest H a l f ) Q u i l l Creek S y n c l i n e 116°/64°SW 30°/278° ( S o u t h e a s t H a l f ) Burwash Creek 110°/74°SW H o r i z o n t a l S y n c l i n e F o l d i n g i n P i c k h a n d l e Lake A r e a 122°/54°SW 10°/294° 36 F o r m a t i o n , and p r e h n i t e - l a u m o n t i t e and c h l o r i t e - e p i d o t e amygdules o c c u r t h r o u g h o u t the N i k o l a i Greenstone. G a b b r o - u l t r a m a f i c complexes a r e s e v e r e l y s e r p e n t i n i z e d and s c h i s t o s e . Q u a r t z - c a l c i t e v e i n s and s t r i n g e r s , l e s s than 15 cm wide and o r i e n t e d p a r a l l e l t o f o l i a t i o n , are numerous i n both S t a t i o n Creek and N i k o l a i v o l c a n i c r o c k s . V a r i o u s amounts o f c h l o r i t e and/or e p i d o t e may o c c u r i n these v e i n s a l o n g w i t h c o p p e r - i r o n s u l p h i d e m i n e r a l s . Read and Monger (1976) s u g g e s t t h a t t h e main i n t e r v a l o f d e f o r m a t i o n and metamorphism f o r the Kluane P e r m o - T r i a s s i c sequence was between 117 and 131 Ma and p o s s i b l y between 117 and 126 Ma. Potassium/argon age d e t e r m i n a t i o n s f o r metamorphism o f t h e N i k o l a i Greenstone are 115 and 122 Ma ( S i n c l a i r e t a l _ . , 1979) and 91 t o 131 Ma ( S i l v e r m a n e t a l _ . , 1980),thus, an i n t e r v a l o f d e f o r m a t i o n and r e g i o n a l metamorphism d u r i n g t h e C r e t a c e o u s i s w e l l documented. COPPER METALLOGENY OF THE SAINT ELIAS FOOTHILLS Lode m i n e r a l d e p o s i t s , m a i n l y c o p p e r - b e a r i n g , have been known i n t h e f o o t h i l l s o f the S a i n t E l i a s Mountains s i n c e b e f o r e t h e t u r n o f the c e n t u r y (Hayes, 1892). D e s p i t e t h i s , e x p l o r a t i o n has l e d t o the l o c a t i o n o f o n l y two d e p o s i t s t h a t w a r r a n t e d development, t h e Well green and Johobo d e p o s i t s , both o f which produced l i m i t e d q u a n t i t i e s o f ore o v e r v e r y s h o r t time p e r i o d s . A number o f the p r i n c i p a l n i c k e l - c o p p e r showings i n the Q u i l l Creek and White R i v e r areas and a copper showing n e a r P i c k h a n d l e Lake (see F i g u r e 4) were mapped i n d e t a i l by the w r i t e r and comprehensive d e s c r i p t i o n s o f each a r e i n c l u d e d i n Appendix A l . A l s o i n c l u d e d are 37 s h o r t g e o l o g i c d e s c r i p t i o n s o f two showings o f copper i n the Q u i l l Creek a r e a . C l a s s i f i c a t i o n o f M i n e r a l D e p o s i t s Read and Monger (1976) d i v i d e l o d e base metal o c c u r r e n c e s o f t h e Kluane Ranges i n t o f i v e c a t e g o r i e s : (1) n i c k e l - c o p p e r - p l a t i n u m ; (2) copper i n N i k o l a i Greenstone; (3) copper i n S k o l a i Group; (4) porphyry c o p p e r d e p o s i t s ; and (5) s i l v e r - l e a d v e i n s . Category 5 i s r a r e and c o n c e r n here i s m a i n l y w i t h the f i r s t f o u r d i v i s i o n s . Each o f the f o u r c a t e g o r i e s o f d e p o s i t s w i l l be c o n s i d e r e d , as r e g a r d s g e n e r a l c h a r a c t e r i s t i c s and o r i g i n , i n o r d e r o f d e c r e a s i n g age o f h o s t r o c k . Copper i n S k o l a i Group - R e l a t i v e l y few showings a r e known, but one o c c u r r e n c e , the M Group c l a i m s near P i c k h a n d l e Lake, has been s t u d i e d i n d e t a i l by the w r i t e r (Appendix A l ) . Here, p y r i t e and minor c h a l c o p y r i t e o c c u r w i t h i n S t a t i o n Creek t u f f s as d i s s e m i n a t i o n s and s m a l l l e n s e s , measuring 0.5 by 1 cm. C h a l c o p y r i t e i s a l s o d i s s e m i n a t e d i n the b a s a l t i c a n d e s i t e flows and, l o c a l l y , forms 15 t o 30 cm wide zones which are comprised o f about 5 p e r c e n t by volume c h a l c o p y r i t e . S u l p h i d e o c c u r r e n c e s are g e n e r a l l y s t r a t i f o r m , l y i n g w i t h i n a m i n e r a l i z e d h o r i z o n , p a r a l l e l to and s t r a d d l i n g t h e i n t e r f a c e between u n d e r l y i n g flows and o v e r l y i n g c o a r s e - g r a i n e d t u f f a c e o u s r o c k s . C h a l c o p y r i t e and minor p y r r h o t i t e o c c u r i n q u a r t z - c a l c i t e - e p i d o t e v e i n s and seams, e i t h e r s i n g l y o r i n p a r a l l e l groups, c u t t i n g p r i m a r y l a y e r i n g o f the S t a t i o n Creek v o l c a n i c r o c k s . On t h e p i c k h a n d l e p r o p e r t y t h e s e v e i n s a r e proximal t o d i s s e m i n a t e d p y r i t e and c h a l c o p y r i t e . V e i n i n g i s most prominent w i t h i n a m i n e r a l i z e d h o r i z o n , 360 m by 2 km, which o v e r l a p s t h e f l o w - t u f f i n t e r f a c e . F i n e l y d i s s e m i n a t e d p y r i t e and minor c h a l c o p y r i t e o c c u r w i t h i n 38 t h i n l y banded a r g i l l a c e o u s c h e r t , c h e r t y t u f f , s i l t s t o n e , and a r g i l l a c e o u s l i m e s t o n e o f the T r a n s i t i o n Zone. The s u l p h i d e s are c o n c e n t r a t e d d o m i n a n t l y a l o n g the c o a r s e r - g r a i n e d l a y e r s , g e n e r a l l y a p p e a r i n g s t r a t a b o u n d . C h e r t and g r e y - g r e e n a r g i l l i t e w i t h i n t e r c a l a t e d c h e r t y t u f f bands c o n t a i n most o f t h e p y r i t e a t t h e North Showing on Canalask p r o p e r t y . Here, s u l p h i d e s g e n e r a l l y f o l l o w the b a n d i n g , but may l i e a l o n g f r a c t u r e s c r o s s i n g the l a m i n a e . C h a l c o p y r i t e i s more prominent i n the l i m y a r g i l l i t e s and d i r t y l i m e s t o n e s 430 m e a s t o f t h e North Showing. The c h a l c o p y r i t e o c c u r s as d i s s e m i n a t i o n s and a l o n g f r a c t u r e s . The s t r a t i f o r m n a t u r e o f d i s s e m i n a t e d c h a l c o p y r i t e and p y r i t e i n h o r i z o n s p a r a l l e l t o and s t r a d d l i n g the b a s a l t i c a n d e s i t e f l o w - t u f f i n t e r f a c e s u g g e s t a s y n g e n e t i c o r e a r l y d i a g e n e t i c o r i g i n f o r the s u l p h i d e s . V e i n s u l p h i d e s i n the b a s a l t i c a n d e s i t e a r e , on the o t h e r hand, e p i g e n e t i c . C l o s e s p a t i a l a s s o c i a t i o n o f v e i n s u l p h i d e s w i t h the s t r a t i f o r m m i n e r a l i z e d h o r i z o n a t P i c k h a n d l e p r o p e r t y s u g g e s t s g e n e s i s by l o c a l m o b i l i z a t i o n o f t h e p r e - e x i s t i n g d i s s e m i n a t e d s u l p h i d e s . The o v e r l a p p i n g n a t u r e o f s u l p h u r i s o t o p i c c o m p o s i t i o n s o f the two types o f d e p o s i t s u p p o r t t h i s i n t e r p r e t a t i o n . L i m i t e d movement o f connate w a t e r o r water o f d e h y d r a t i o n may have p r o v i d e d the mechanism f o r t r a n s p o r t o f t h e m e t a l s and s u l p h u r and r e d e p o s i t i o n as s u l p h i d e s i n v e i n s : D i s s e m i n a t e d p y r i t e i n T r a n s i t i o n Zone s e d i m e n t a r y and t u f f a c e o u s s e d i m e n t a r y r o c k s i s g e n e r a l l y s t r a t a b o u n d , i n d i c a t i n g a s y n g e n e t i c o r i g i n . The e x t r e m e l y l i g h t s u l p h u r i s o t o p i c v a l u e s s u p p o r t b i o g e n i c r e d u c t i o n o f s eawater s u l p h a t e t o form p y r i t e (Ohmoto and Rye, 1979). F i n e l y d i s s e m i n a t e d and f r a c t u r e - r e l a t e d c h a l c o p y r i t e i n a r g i l l a c e o u s 39 l i m e s t o n e and b l a c k s h a l e o f the T r a n s i t i o n Zone may have formed by v o l c a n i c - h y d r o t h e r m a l a c t i v i t y . The r e d u c i n g s e d i m e n t a r y r o c k s would have been c h e m i c a l l y r e a c t i v e t o any c o p p e r - b e a r i n g f u m a r o l i c s o l u t i o n s p e n e t r a t i n g through from t h e u n d e r l y i n g t u f f a c e o u s and v o l c a n i c s e c t i o n . N i c k e l - C o p p e r A s s o c i a t e d w i t h U l t r a m a f i c I n t r u s i o n s P y r r h o t i t e , p e n t l a n d i t e , and c h a l c o p y r i t e are p r e s e n t i n massive o r e pods, as n e t - t e x t u r e d s u l p h i d e s , and as d i s s e m i n a t e d s u l p h i d e s a s s o c i a t e d w i t h Lower Group Kluane complexes. Massive ore pods o c c u r a t the base o f t h e u l t r a m a f i c s i l l s o r i n f o o t w a l l r o c k s . P e r i d o t i t e and a b o r d e r phase o l i v i n e gabbro c o n t a i n d i s s e m i n a t e d and n e t - t e x t u r e d s u l p h i d e s , r e s p e c t i v e l y . The d i s s e m i n a t e d s u l p h i d e s i n the p e r i d o t i t e occupy i n t e r c u m u l u s s i t e s t o o l i v i n e c r y s t a l s , but may o c c u r w i t h i n i n d i v i d u a l pyroxene g r a i n s . At the Well green p r o p e r t y gabbro l i e s a l o n g the s t r u c t u r a l base o f the p e r i d o t i t e . T h i s gabbro i s p e t r o g r a p h i c a l l y and c h e m i c a l l y s i m i l a r t o the Maple Creek gabbros. N e t - t e x t u r e d and h e a v i l y d i s s e m i n a t e d s u l p h i d e m i n e r a l s i n the gabbro are t h e same as t h o s e i n the p e r i d o t i t e and i n massive ore pods s t r u c t u r a l l y below t h e gabbro. S u l p h i d e b l e b s i n the gabbro a r e v a r i a b l e i n s i z e and l a r g e r b l e b s a r e commonly f r a c t u r e d and s u r r o u n d e d by s m a l l e r b l e b s . T i n y c r y s t a l s o f pyroxene, p a r t l y a l t e r e d t o t r e m o l i t e - a c t i n o l i t e , o f t e n r i m s u l p h i d e s i n the gabbro. Campbell (1960) i n t e r p r e t s a magmatic t o hydrothermal o r i g i n f o r the d e p o s i t s . E c k s t r a n d (1972) c l a s s i f i e s the s u l p h i d e b o d i e s as magmatic i n j e c t i o n t y p e . The n i c k e l - c o p p e r d e p o s i t s have been deformed e x t e n s i v e l y and accompanying u l t r a m a f i c r o c k s have been s e v e r e l y s e r p e n t i n i z e d , s h e a r e d , and f o l d e d . P e n e t r a t i v e d e f o r m a t i o n f e a t u r e s 40 a r e p r e s e n t l o c a l l y i n the s u l p h i d e s , but r e l i c t p r i m a r y t e x t u r e s a r e abundant and s u p p o r t a magmatic o r i g i n . T e x t u r a l f e a t u r e s , such as i n t e r c u m u l u s and n e t - t e x t u r e d s u l p h i d e b l e b s and s u l p h i d e s w i t h i n pyroxene c r y s t a l s , combined w i t h an upward p r o g r e s s i o n i n t h e ore from massive t o n e t t o d i s s e m i n a t e d s u l p h i d e s a r e s t r o n g e v i d e n c e f o r f o r m a t i o n o f t h e n i c k e l - c o p p e r d e p o s i t s by s e p a r a t i o n o f i m m i s c i b l e s u l p h i d e l i q u i d from t he u l t r a m a f i c magma. At Canalask p r o p e r t y h e a v i l y d i s s e m i n a t e d s u l p h i d e s i n the u l t r a m a f i c s i l l n e a r i t s base and "f l o w " t e x t u r e s and rounded w a l l r o c k x e n o l i t h s i n o r e pods w i t h i n f o o t w a l l r o c k s s u p p o r t m o b i l i z a t i o n o f the s u l p h i d e l i q u i d a f t e r g r a v i t a t i o n a l s e p a r a t i o n from t h e p a r e n t magma. S h e a r i n g and f o l d i n g d u r i n g r e g i o n a l d e f o r m a t i o n have c e r t a i n l y p l a y e d an i m p o r t a n t r o l e i n d e t e r m i n i n g t he p r e s e n t c o n f i g u r a t i o n o f the massive o r e pods a t a l l the p r o p e r t i e s . T r a c e element a n a l y s e s o f u n m i n e r a l i z e d u l t r a m a f i c r o c k s i n Kluane complexes o f t h e Upper Group ( C h a p t e r 3) show high c o p p e r (208 and 350 ppm) and high n i c k e l (1310 anid 1660 ppm) c o n t e n t s . T h e r e f o r e t he u l t r a m a f i c magma was the l i k e l y s o u r c e o f the m e t a l s . S u l p h u r i s o t o p i c c o m p o s i t i o n s a r e u n u s u a l l y e n r i c h e d i n the l i g h t e r 32 i s o t o p e , S, and s u g g e s t c o n t a m i n a t i o n o f magmatic s u l p h u r by p y r i t i c s u l p h u r i n T r a n s i t i o n Zone w a l l r o c k s ( C h a p t e r 4 ) . Copper i n N i k o l a i Greenstone N a t i v e copper i s c o n c e n t r a t e d s p o r a d i c a l l y i n b a s a l t flows o f the N i k o l a i G r e e n s t o n e , as a t S i l v e r C i t y p r o p e r t y . The copper g e n e r a l l y o c c u r s i n v e i n s and where the v e i n s appear i n s u b p a r a l l e l groups t h e o v e r a l l m i n e r a l i z e d zone i s r o u g h l y t a b u l a r and conformable t o b e d d i n g . Some n a t i v e copper o c c u r s as small d i s s e m i n a t e d g r a i n s i n d e v i t r i f i e d f l o w tops ( S i n c l a i r ejt a l _ . , 1979). 41 C o p p e r - i r o n s u l p h i d e s o c c u r i n c r o s s - c u t t i n g v e i n s and amygdules i n the N i k o l a i f l o w s . The p a r a g e n e t i c sequence i s , from o l d e s t t o y o u n g e s t : p y r i t e ; c h a l c o p y r i t e ; b o r n i t e ; c h a l c o c i t e ; and minor n a t i v e copper. The c o p p e r m i n e r a l s are i n t i m a t e l y a s s o c i a t e d w i t h one o r more o f the f o l l o w i n g : p r e h n i t e ; p u m p e l l y i t e ( a t S i l v e r C i t y p r o p e r t y ) ; l a u m o n t i t e ; c a l c i t e ; c h l o r i t e ; and minor e p i d o t e . V e i n i n g i s e x t e n s i v e i n the N i k o l a i b a s a l t and some v e i n s appear t o c r o s s the lower d i s -c o n f o r m i t y i n t o Hasen Creek Formation o r t h e upper c o n t a c t i n t o the C h i t i s t o n e and N i z i n a l i m e s t o n e s . The o c c u r r e n c e o f t a b u l a r m i n e r a l i z e d zones o f n a t i v e copper s u b p a r a l l e l t o b e d d i n g and d i s s e m i n a t e d g r a i n s o f n a t i v e copper i n d e v i t r i f i e d and h e m a t i t i c f l o w tops o f t h e N i k o l a i Greenstone s u g g e s t t h a t t h e c o p p e r formed as a p r o d u c t o f e x t e n s i v e s u b a e r i a l w e a t h e r i n g o f t h e b a s a l t p i l e (see S i n c l a i r e_t a l _ . , 1979; Kirkham, 1972). I m p l i c i t i n such a g e n e t i c model i s t h a t t h e age o f f o r m a t i o n o f n a t i v e copper i s o n l y s l i g h t l y y o unger than the age o f the Upper T r i a s s i c N i k o l a i b a s a l t s . The i n t i m a t e a s s o c i a t i o n o f c o p p e r - i r o n s u l p h i d e s and metamorphic m i n e r a l s , such as p r e h n i t e and p u m p e l l y i t e , i n v e i n s and amygdules i n the N i k o l a i Greenstone and t h e s u l p h i d e p a r a g e n e s i s o f p y r i t e through c h a l c o p y r i t e t o b o r n i t e , c h a l c o c i t e , and minor n a t i v e copper are e v i d e n c e f o r s u l p h i d e f o r m a t i o n d u r i n g low grade r e g i o n a l metamorphism i n an open system ( i e . i n response t o i n c r e a s i n g oxygen f u g a c i t y ) . The e x t r e m e l y broad range o f s u l p h u r i s o t o p i c c o m p o s i t i o n s s u p p o r t t h i s i n t e r p r e t a t i o n . The presence o f h i g h c o p p e r i n the b a s a l t flows (up t o 115 ppm i n the Q u i l l Creek a r e a and about 150 ppm a t S i l v e r C i t y p r o p e r t y ( S i n c l a i r e t aj_., 1979)) s u g g e s t s t h a t t h e N i k o l a i was 42 the s o u r c e o f copper i n t h e v e i n d e p o s i t s . Connate water and water o f d e h y d r a t i o n p r o b a b l y formed t h e ore f l u i d s t h a t d e r i v e d and t r a n s p o r t e d copper t o s i t e s o f d e p o s i t i o n i n v e i n s i n the N i k o l a i Greenstone. Copper-Molybdenum i n F e l s i c I n t r u s i o n s A l t h o u g h not p a r t o f t h i s s t u d y , b r i e f mention s h o u l d be made o f t h i s t y p e o f copper d e p o s i t . The Cork p r o p e r t y i s u n d e r l a i n by a q u a r t z l a t i t e p o r p h y r y s t o c k , which i n t r u d e s t h e d i s c o n f o r m i t y between s e d i m e n t a r y r o c k s o f Hasen Creek Formation and b a s a l t flows o f the N i k o l a i Greenstone ( C h r i s t o p h e r ejt a j _ . , 1972). Numerous f r a c t u r e s w i t h i n t h e s t o c k a r e f i l l e d w i t h q u a r t z and p y r i t e , c h a l c o p y r i t e , and minor m o l y b d e n i t e o c c u r both i n t h e f r a c t u r e s and as d i s s e m i n a t i o n s i n t h e porphyry and a d j a c e n t c o u n t r y r o c k s (Read and Monger, 1976). S i m i l a r p o r p h y r y d e p o s i t s a r e a s s o c i a t e d w i t h C r e t a c e o u s p l u t o n s i n the E a s t e r n A l a s k a Range. Source o f t h e copper i n t h e s e d e p o s i t s may be a d j a c e n t N i k o l a i b a s a l t flows ( R i c h t e r ejt a l _ . , 1975). Porp h y r y d e p o s i t s , i n g e n e r a l , are thought to form by d e p o s i t i o n from geothermal systems r e l a t e d t o i n t r u s i o n s t h a t i n many cases were f e e d e r s f o r s t r a t o v o l canoes (see S i H i t o e , 1973). Much c o n t r o v e r s y e x i s t s as to t h e s o u r c e o f m e t a l s , b u t the ore f l u i d s themselves have been shown to be l a r g e l y non-magmatic i n o r i g i n ( T a y l o r , 1979). The Cork p r o p e r t y i s the o n l y p o r p h y r y d e p o s i t near the a r e a o f i n v e s t i g a -t i o n and i t s g e n e r a l f e a t u r e s , d e s c r i b e d by C h r i s t o p h e r et_ a]_. ( 1972) and summarized by P i l c h e r and McDougall (1976), are t y p i c a l o f p h a l l i c p orphyry d e p o s i t s . Such d e p o s i t s a r e a s s o c i a t e d w i t h high l e v e l p l u t o n s , emplaced i n u n r e l a t e d h o s t r o c k s , i n a l a t e o r p o s t o r o g e n i c - s e t t i n g ( S u t h e r l a n d Brown, 1976). 43 M e t a l l o g e n y S p a t i a l d i s t r i b u t i o n o f the v a r i o u s types o f c o p p e r d e p o s i t s i s shown both i n p l a n view and i n c r o s s s e c t i o n i n F i g u r e s 4 and 5, r e s p e c t i v e l y . A l l , e x c e p t S i l v e r C i t y copper d e p o s i t , l i e w i t h i n a narrow, r o u g h l y 10 km wide, b e l t t h a t t r e n d s n o r t h w e s t e r l y a l o n g the l e n g t h o f t h e Kluane Ranges. S i l v e r C i t y p r o p e r t y i s exposed a l o n g the Duke R i v e r F a u l t , about 15 km southwest o f the m i n e r a l i z e d b e l t , and i t i s t h i s f a u l t i n g t h a t may a c c o u n t f o r the i s o l a t e d p o s i t i o n o f the S i l v e r C i t y d e p o s i t . The d i s t r i b u t i o n o f m i n e r a l d e p o s i t s w i t h time i s shown i n T a b l e 6. The f i r s t e c o n o m i c a l l y s i g n i f i c a n t development o f copper m i n e r a l i z a t i o n o c c u r r e d d u r i n g Lower T r i a s s i c time w i t h the f o r m a t i o n o f massive t o d i s s e m i n a t e d n i c k e l - c o p p e r d e p o s i t s a s s o c i a t e d w i t h the Kluane gabbro-u l t r a m a f i c complexes. Copper d e p o s i t s i n the S t a t i o n Creek v o l c a n i c rocks and i n r o c k s o f the T r a n s i t i o n Zone a l s o p r e - d a t e d e f o r m a t i o n and metamorphism. The c o n c e n t r a t i o n mechanism f o r copper i n v e i n s i n both S t a t i o n Creek and N i k o l a i v o l c a n i c r o c k s was r e g i o n a l metamorphism and t h e r e f o r e a C r e t a c e o u s age i s a l s o the age o f m i n e r a l i z a t i o n . Thus, magmatic s e g r e g a t i o n and metamorphic-hydrothermal mechanisms have p l a y e d dominant r o l e s i n f o r m a t i o n o f l o d e copper d e p o s i t s i n the Kluane Ranges. Without the p r e s e n c e o f u b i q u i t o u s c o p p e r metal i n r o c k s o f t h e P e r m o - T r i a s s i c sequence o f t h e Kluanes the o n l y s i g n i f i c a n t d e p o s i t s formed would have been the n i c k e l - c o p p e r s u l p h i d e s a s s o c i a t e d w i t h i n t r u s i v e u l t r a m a f i c s i l l s . And w i t h o u t the p r e s e n c e o f s u b s t a n t i a l s u l p h u r i n p y r i t i c r o c k s o f the T r a n s i t i o n Zone, even t h e n i c k e l - c o p p e r d e p o s i t s would have been g r e a t l y reduced i n s i z e and perhaps would h o t have formed a t a l l . 44 F i g u r e 4. L o c a t i o n o f p r i n c i p a l base metal o c c u r r e n c e s f o r m i n g p a r t o f t h i s m e t a l l o g e n e t i c s t u d y i n the f o o t h i l l s o f S a i n t E l i as Mountains, Yukon T e r r i t o r y . D e p o s i t s a r e l o c a t e d as f o l l o w s : l=Cu-Fe a t P i c k h a n d l e p r o p e r t y ; 2=Ni-Cu a t Cana l a s k p r o p e r t y ; 3=Ni-Cu a t Arch Creek p r o p e r t y ; 4=Ni-Cu a t Well green Mine; 5=Ni-Cu a t L i n d a Creek p r o p e r t y ; 6=Cu a t S i l v e r C i t y p r o p e r t y ; 7=Cu a t Q u i l l Creek Mines p r o p e r t y ; 8=Cu a t A l i c e Lake Mines p r o p e r t y ; 9=Cu-Mo a t Cork p r o p e r t y . F i g u r e 5. Schematic c r o s s s e c t i o n o f mineral o c c u r r e n c e s and s t r a t i g r a p h y i n the Kluane Ranges. I n t r u s i o n s and m i n e r a l o c c u r r e n c e s are shown i n i d e a l i z e d f a s h i o n , but r o u g h l y i n t h e i r c o r r e c t " s t r a t i g r a p h i c " p o s i t i o n s . 46 TABLE 6. D i s t r i b u t i o n o f m i n e r a l o c c u r r e n c e s w i t h time i n the Kluane Ranges. AGE MINERAL DEPOSIT METALS GEOLOGIC PROCESS T e r t i a r y Porphyry-Type Cu -Mo I n t r u s i o n o f small q u a r t z l a t i t e p o r p h y r y s t o c k s a t d i s c o n f o r m i t y between Hasen Creek Formation and N i k o l a i Greenstone. G r a n i t i c i n t r u s i o n s C r e t a c e o u s V e i n Type Cu -Fe R e g i o n a l metamorphism, p o s s i b l y d e - w a t e r i n g o f s t r a t a . D e p o s i t i o n o f N i z i n a and C h i t i s t o n e l i m e s t o n e s . Upper T r i a s s i c D i s s e m i n a t e d Cu i n T a b u l a r Bodies N a t i v e Cu Supergene e n r i c h m e n t d u r i n g s u b a e r i a l w e a t h e r i n g o f b a s a l t f l o w s . Lower T r i a s s i c Magmatic Ni c k e l - C o p p e r A s s o c i a t e d With Gabbro-U l t r a m a f i c Complexes Cu (--Ni Pt-Co) P a r t i a l m e l t i n g o f p y r o l i t i c upper mantle and f o r m a t i o n o f i m m i s c i b l e s u l p h i d e m e l t which s e t t l e s a t base o f p e r i d o t i t i c s i l l s . D e p o s i t i o n o f Hasen Ck. Fm. s e d i m e n t a r y r o c k s . Lower Permian D i s s e m i n a t e d A l o n g Bands In S e d i m e n t - T u f f Zone Fe -Cu B i o g e n i c r e d u c t i o n o f seawater s u l p h a t e i n e u x i n i c e n v i ronment. D i s s e m i n a t e d i n Basal t i c A n d e s i t e Cu -Fe F u m a r o l i c a c t i v i t y a s s o c i a t e d w i t h v o l c a n i c flow and t u f f f o r m a t i o n 47 GEOLOGICAL EVOLUTION OF THE QUILL CREEK AREA L i t h o l o g i c a s p e c t s o f the P e r m o - T r i a s s i c s t r a t i g r a p h y i n d i c a t e a " e u g e o s y n c l i n a l " a s s o c i a t i o n . In summary, the s e c t i o n c o n s i s t s o f a d o m i n a n t l y p y r o c l a s t i c v o l c a n i c u n i t , o v e r l a i n by an a r g i l l i t e -1imestone-greywacke sequence, i n t u r n , o v e r l a i n by b a s a l t f l o w s . T h i s s t r a t i g r a p h y c o r r e s p o n d s t o a c i r c a l i t t o r a l (46 t o 183 m water depth) o r a r e s t r i c t e d l a g o o n a l environment (Krumbein and S l o s s , 1963). During Lower Permian time e x t r u s i o n o f p i l l o w e d b a s a l t i c a n d e s i t e f l o w s gave way t o d e p o s i t i o n o f a t h i c k s e c t i o n o f massive t o t h i n l y bedded f i n e - and medium-grained t u f f s and l a p i l l i t u f f s o f more a n d e s i t i c c o m p o s i t i o n . Limestone and s h a l e were i n t e r b e d d e d w i t h the uppermost f l o w s and t u f f a c e o u s r o c k s and, l o c a l l y , t he t u f f s were succeeded by a n d e s i t i c agglomerate and v o l c a n i c b r e c c i a . D e p o s i t i o n o f S t a t i o n Creek Formation was subaqueous as i n d i c a t e d by the p i l l o w e d f l o w s w i t h s p a r s e v e s i c l e s , the massive t o t h i n l y bedded t u f f s w i t h i n t e r l a y e r e d s h a l e and s i l t s t o n e , and the l i m e s t o n e u n i t s w i t h i n t u f f a c e o u s and f l o w s e c t i o n s . These l a t t e r l i m e s t o n e beds commonly c o n t a i n c h e r t n o d u l e s . The w h i t e t r a n s l u c e n t c h e r t i s lumpy and l e n s - s h a p e d , c o n c e n t r a t e d a l o n g b e d d i n g p l a n e s , and may form d i s c r e t e l a y e r s . B l a t t ejt a]_. (1972) r e f e r t o c h e r t n o d u l e s i n l i m e s t o n e and mention t h a t they o c c u r l a r g e l y i n s h e l f and b a s i n a l areas o f a c a r b o n a t e bank d e p o s i t . The c o m p o s i t i o n and s t r u c t u r e o f s u l p h i d e - b e a r i n g S t a t i o n Creek v o l c a n i c r o c k s , l a c k o f "basement", and presence o f i n t e r b e d d e d sub-aqueous s e d i m e n t a r y r o c k s i n the f o r m a t i o n s u p p o r t a v o l c a n i c a r c environment. I n t e r p r e t a t i o n o f the S t a t i o n Creek Formation i n A l a s k a 48 as an: a r c assemblage d e v e l o p e d on o c e a n i c c r u s t was f i r s t proposed by R i e n t e r and Jones (1973) and l a t e r s u p p o r t e d by Monger (1977) f o r e q u i v a l e n t r o c k s i n Canada. F i n e - g r a i n e d t u f f i n t e r c a l a t e d w i t h an upwardly i n c r e a s i n g volume o f a r g i l l i t e , carbonaceous s h a l e , c h e r t , and a r g i l l a c e o u s l i m e s t o n e i n the upper 400 m o f S t a t i o n Creek Formation shows r a p i d l y waning vol cam'sm. The p r e s e n c e o f t h e s e o r g a n i c - r i c h s h a l e s , t h e s i l t y m a t e r i a l , and the l i m e s t o n e w i t h a h i g h a r g i l l a c e o u s c o n t e n t s u g g e s t d e p o s i t i o n i n a r e s t r i c t e d b a s i n o r b r a c k i s h water environment. The e u x i n i c environment i s s u p p o r t e d by s u l p h u r i s o t o p i c c o m p o s i t i o n s f o r s u l p h i d e s i n the T r a n s i t i o n Zone. A b a c k - a r c b a s i n i s a p o s s i b l e environment which f i t s t hese c r i t e r i a . A subaqueous b a s i n e x i s t e d t h r o u g h o u t d e p o s i t i o n o f Hasen Creek s e d i m e n t a r y r o c k s . The p r e s e n c e o f t h r e e d i s t i n c t l i m e s t o n e u n i t s w i t h i n the s t r a t i g r a p h i c sequence s u g g e s t s c o n s i d e r a b l e f l u c t u a t i o n i n w a t er depth d u r i n g t h i s t i m e . Source o f the d e t r i t a l m a t e r i a l appears to have been from the e r o d i n g v o l c a n i c c e n t e r s . The Hasen Creek sequence l a c k s t h e h i g h carbonaceous and a r g i l l a c e o u s c o n t e n t o f t h e T r a n s i t i o n Zone, a l s o t h e h i g h s u l p h i d e c o n t e n t , which s u g g e s t s i n c r e a s e d c i r c u l a t i o n i n t h e s e d i m e n t a r y b a s i n . Thus a b a c k - a r c b a s i n f i t s the e n t i r e Permian s e d i m e n t a r y sequence. U p l i f t and e r o s i o n between Lower Permian and Upper T r i a s s i c times a r e marked by a d i s c o n f o r m i t y . D u r i n g t h e Lower T r i a s s i c , Kluane g a b b r o - u l t r a m a f i c complexes i n t r u d e d as s i l l s w i t h i n S t a t i o n Creek and Hasen Creek F o r m a t i o n s . The chemical data f o r t h e s e complexes s u g g e s t s t h a t t h e y were d e r i v e d by p a r t i a l m e l t i n g o f upper mantle p y r o l i t e ( C h a p t e r 3 ) . 49 G e n e r a t i o n o f t h e Lower T r i a s s i c k o m a t i i t i c and s u l p h i d e - b e a r i n g p e r i d o t i t e s i l l s s u g g e s t s a t e n s i o n a l o r r i f t i n g mechanism i n the b a s i n and u p w e l l i n g o f upper mantle d i a p i r s . K a r i g (1971) mentions t h a t e x t e n s i o n commonly o c c u r s on the concave s i d e o f a consuming a r c , l e a d i n g t o a sequence o f e v e n t s i n v o l v i n g s i m u l t a n e o u s u p w e l l i n g o f magma and f a i l u r e o f t h e o c e a n i c l i t h o s p h e r e . V o l c a n i s m r e t u r n e d d u r i n g Upper T r i a s s i c time w i t h f o r m a t i o n o f a b a s a l t i c b r e c c i a and p i l l o w b r e c c i a . An i n t e r m i t t e n t e r o s i o n a l p e r i o d must have f o l l o w e d d e p o s i t i o n o f t h i s b r e c c i a , l e a v i n g o n l y s m a l l p o c k e t s o f t h e r o c k below the l a v a p i l e . A s h a l l o w water environment was p r e s e n t d u r i n g p a r t o f the Upper T r i a s s i c v o l c a n i s m , as e v i d e n c e d by i n t e r b e d d e d s h a l e and l i m e s t o n e i n the lower and m i d d l e p a r t s o f the b a s a l t p i l e . Maple Creek gabbro s i l l s and dykes may w e l l r e p r e s e n t remnants o f a f e e d e r system f o r the f l o w s . C o n t i n u e d d e p o s i t i o n o f a s u c c e s s i o n o f h i g h l y v e s i c u l a r , n o n - p i l l o w e d b a s a l t s w i t h h e m a t i t i c f l o w tops i n d i c a t e s emergence t o an e x t r e m e l y s h a l l o w water o r , most l i k e l y , a s u b a e r i a l e n v i r o n m e n t . I r o n e n r i c h m e n t o f upper f l o w tops i s documented by Macdonald (1967) and Moore (1965) mentions t h a t v e s i c u l a t i o n i n a b a s a l t c o n t a i n i n g 0.45 w e i g h t p e r c e n t water and a t a temperature o f 1100°C would not be p o s s i b l e below 800 m water depth due t o c o n f i n i n g p r e s s u r e . Weathering o f t h e s e b a s a l t s l e d to the f o r m a t i o n o f the n a t i v e c o p p e r d e p o s i t s by supergene e n r i c h m e n t . G e n e r a t i o n o f t h e N i k o l a i may have been due to c o n t i n u e d r i f t i n g i n the proposed b a c k - a r c b a s i n . Chemical and s t r u c t u r a l s i m i l a r i t i e s o f N i k o l a i Greenstone to o c e a n i c r i d g e and i s l a n d b a s a l t s s u p p o r t s t h i s i d e a . D e p o s i t i o n o f the C h i t i s t o n e and N i z i n a l i m e s t o n e i n Upper T r i a s s i c time marks the end o f v o l c a n i s m . During d e p o s i t i o n o f t h e s e l i m e s t o n e 50 u n i t s the d e p o s i t i o n s ! environment must have been t r a n s f o r m e d t o a s h a l l o w subaqueous b a s i n . Deformation and metamorphism o f t h i s P e r m o - T r i a s s i c sequence o c c u r r e d d u r i n g t h e C r e t a c e o u s . Subsequent emplacement o f t h e Kluane Range g r a n i t i c i n t r u s i o n s , dated a t 115 t o 117 Ma ( C h r i s t o p h e r ejt a_l_., 1972) was e s s e n t i a l l y c o n c o m i t a n t w i t h g r a n i t i c p l u t o n i s m i n the E a s t e r n A l a s k a Range, dated a t 105 t o 117 Ma ( R i c h t e r e t a l _ . , 1975). A f i n a l s t a g e o f magmatism o c c u r r e d d u r i n g the T e r t i a r y as e v i d e n c e d by small s t o c k s and dykes o f q u a r t z l a t i t e p o r p h y r y , dated a t 26 Ma by C h r i s t o p h e r e t a l . (1972). ACKNOWLEDGEMENTS F i n a n c i a l s u p p o r t f o r t h i s s t u d y was o b t a i n e d m a i n l y from t he N a t i o n a l Research C o u n c i l o f Canada through an N.R.C. P o s t g r a d u a t e S c h o l a r s h i p t o S.W. Campbell and o p e r a t i n g g r a n t s t o Dr. A . J . S i n c l a i r . F i e l d s u p p o r t i n c l u d i n g h e l i c o p t e r time was p r o v i d e d by the G e o l o g i c a l Survey o f Canada, Department o f I n d i a n and N o r t h e r n A f f a i r s , and Western Mines L t d . , Vancouver. V a r i o u s a s p e c t s o f t h i s s t u d y have been d i s c u s s e d w i t h numerous i n d i v i d u a l s , i n c l u d i n g Drs. R.B. Campbell, J.W.H. Monger, ' P.B. Read, D.B. C r a i g , E.M. MacKevett, J r . , C . I. Godwin, and A.E. S o r e g a r o l i . C.A. A i r d , J.S. V i n c e n t , D. Tenny, P. V e r s l u c e , W.B. Green, R. C h e r l e t , and R. Mac i n t o s h have a l s o c o n t r i b u t e d t o d i s c u s s i o n s and/or a l l o w e d a c c e s s t o p r e v i o u s e x p l o r a t i o n work on the v a r i o u s p r o p e r t i e s i n the s t u d y a r e a s . M. M u e h l e r t and H. P i l t z a s s i s t e d i n the f i e l d work. 51 REFERENCES A r n d t , N.T., 1977, T h i c k , l a y e r e d p e r i d o t i t e - g a b b r o l a v a flows i n Munro Township, O n t a r i o ; Can. J o u r . E a r t h S c i . , V o l . 14, p. 2620-2637. A r n d t , N.T., N a l d r e t t , A . J . , and Pyke, D.R., 1977, K o m a t i i t i c and i r o n -r i c h t h o l e i i t i c l a v a s o f Munro Township, N o r t h e a s t O n t a r i o ; J o u r . P e t r o l ., V o l . 18, p. 319-369. 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G e o l . , V o l . 71, p. 1131-1158. N a l d r e t t , A . J . , and Goodwin, A.M., 1977, V o l c a n i c r o c k s o f t h e B l a k e R i v e r Group, A b i t i b i Greenstone B e l t , O n t a r i o , and t h e i r s u l p h u r c o n t e n t ; Can. J o u r . E a r t h S c i . , V o l . 14, p. 539-550. N a l d r e t t , A . J . , and T u r n e r , A.R., 1977, The geology and p e t r o g e n e s i s o f t h e g r e e n s t o n e b e l t and r e l a t e d n i c k e l s u l p h i d e m i n e r a l i z a t i o n a t Y a k i b i n d i e , Western A u s t r a l i a ; Precambrian Res., V o l . 5, p. 43-103. Ohmoto, H., and Rye, R.0., 1979, I s o t o p e s o f s u l p h u r and c a r b o n ; i n B a r n e s , H.L., ed., G e o c h e m i s t r y o f hydrothermal ore d e p o s i t s , 2nd Ed., New York, John W i l e y and Sons, p. 509-567. P i l c h e r , S.H., and M c D o u g a l l , J . 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R i c h t e r , D.H., Lanphere, M.A., and Matson, N.A., J r . , 1975, G r a n i t i c p l u t o n i s m and metamorphism, E a s t e r n A l a s k a Range, A l a s k a ; G e o l . Soc. Amer. B u l l . 86, p. 819-829. S i l b e r m a n , M.L., MacKevett, E.M., J r . , Connor, C.L., and Matthews, A., 1980, M e t a l l o g e n i c and t e c t o n i c s i g n i f i c a n c e o f oxygen i s o t o p e data and whole-rock potassium-argon ages o f the N i k o l a i G r e e n s t o n e , McCarthy Q u a d r a n g l e , A l a s k a ; U.S. G e o l . Surv. Open F i l e Report 80-2019, . 29p. S i H i t o e , R.H., 1973, The tops and bottoms o f p o r p h y r y copper d e p o s i t s ; Econ. G e o l . , V o l . 68, p. 799-815. S i n c l a i r , A . J . , B e n t z e n , A., and McLeod, J.A., 1979, Geology o f the White R i v e r n a t i v e copper d e p o s i t , Yukon T e r r i t o r y ; Dept. I n d i a n N o r t h e r n A f f . , N o r t h e r n A f f a i r s Program, 27p. S m i t h , J.G., and MacKevett, E.M., J r . , 1970, The S k o l a i Group i n the McCarthy B-4, C-4, and C-5 q u a d r a n g l e s , Wrangell Mountains, A l a s k a ; U.S. G e o l . Surv. B u l l . 1274-Q, p.Ql-Q26. S u t h e r l a n d Brown, A., 1976, Morphology and c l a s s i f i c a t i o n ; i n S u t h e r l a n d Brown, A., e d . , P o r p h y r y d e p o s i t s o f the Canadian C o r d i l l e r a , Can. I n s t . M i n i n g M e t a l l . , Spec. V o l . 15, p.44-51. T a y l o r , H.P., J r . , 1979, Oxygen and hydrogen i s o t o p e r e l a t i o n s h i p s i n hydrothermal m i n e r a l d e p o s i t s ; i n Barnes, H.L., ed., Geochemistry o f hydrothermal ore d e p o s i t s , Second E d i t i o n , New York, John W i l e y and Sons, p. 236-277. Tempelman-Kluit, D.J., 1976, The Yukon C r y s t a l l i n e t e r r a n e : enigma i n the Canadian C o r d i l l e r a ; G e o l . Soc. Amer. B u l l . , 87, p.1343-1357. 54 CHAPTER 3 GABBRO AND ULTRAMAFIC ROCKS, OF THE KLUANE RANGES, YUKON TERRITORY - CORDILLERAN KOMATIITES 55 ABSTRACT Lower T r i a s s i c Kluane g a b b r o - u l t r a m a f i c complexes i n t r u d e v o l c a n i -c l a s t i c and s e d i m e n t a r y r o c k s o f the Lower Permian S t a t i o n Creek and Hasen Creek F o r m a t i o n s . Maple Creek gabbros i n t r u d e t h e s e f o r m a t i o n s and a l s o p e n e t r a t e Upper T r i a s s i c N i k o l a i Greenstone b a s a l t s . Kluane complexes a r e d i v i s i b l e i n t o a Lower and Upper Group, depending on s t r a t i g r a p h i c l e v e l o f i n t r u s i o n . Lower Group complexes c o n s i s t o f p e r i d o t i t e , u n d e r l a i n by d u n i t e , and w i t h a b o r d e r phase o f o l i v i n e gabbro. Dunite formed by g r a v i t y a c c u m u l a t i o n o f o l i v i n e d u r i n g i n i t i a l i n t r u s i o n , w h i l e t h e o l i v i n e gabbro formed by f l o w d i f f e r e n t i a t i o n o f the l a t e r a l l y moving p e r i d o t i t i c magma. Lower Group complexes c o n s i s t o f p e r i d o t i t e o v e r l a i n by gabbro. G r a v i t y a c c u m u l a t i o n o f o l i v i n e and two pyroxenes produced the p e r i d o t i t e , w h i l e . r e s i d u a l l i q u i d -at the top of the s i l l c r y s t a l l i z e d t o gabbro. C h e m i c a l l y , both Lower and Upper Group g a b b r o - u l t r a m a f i c complexes show s t r i k i n g s i m i l a r i t y t o p y r o x e n i t i c and p e r i d o t i t i c k o m a t i i t e s . In a d d i t i o n , t h e i n t e r n a l s t r u c t u r e s o f Kluane complexes are comparable t o t h o s e o f k o m a t i i t i c f l o w s and s i l l s i n Precambrian t e r r a n e s . Upper T r i a s s i c Maple Creek gabbros a r e p y r o x e n e - p l a g i o c l a s e - b e a r i n g s i l l s and dykes, i n t e r p r e t e d as a f e e d e r system f o r Upper T r i a s s i c N i k o l a i G r e e n s t o n e . C h e m i c a l l y , the gabbros and b a s a l t s a r e i n t e r m e d i a t e between b a s a l t i c k o m a t i i t e s and t h o l e i i t e s . INTRODUCTION Most g a b b r o - u l t r a m a f i c b o d i e s i n v o l c a n i c b e l t s o f the C o r d i l l e r a n 56 r e g i o n s o f North America appear t o be e i t h e r o f t h e a l p i n e type o r zoned complexes (McKechnie, 1965; McTaggart, 1971; I r v i n e , 1974) and t h o s e o f Precambrian t e r r a n e s , k o m a t i i t i c ( A r n d t e_t a l _ . , 1977; Pyke et_ a l _ . , 1973; N a l d r e t t and T u r n e r , 1977; V i l j o e n and V i l j o e n , 1969). O c c u r r e n c e s o f P a l e o z o i c k o m a t i i t e s a r e s a i d t o be r a r e and l i m i t e d t o b a s a l t i c k o m a t i i t e s ( G a l e , 1973; Brooks and H a r t , 1974). Lower T r i a s s i c e l o n g a t e g a b b r o - u l t r a m a f i c complexes i n the Kluane Ranges, Yukon T e r r i t o r y , a r e a s s o c i a t e d w i t h s m a l l g a b b r o i c b o d i e s o f prob-a b l e Upper T r i a s s i c age. C e r t a i n o f the complexes a r e h o s t s t o n i c k e l -c o pper s u l p h i d e d e p o s i t s . T h i s paper d e a l s w i t h the p e t r o g r a p h i c and c h e m i c a l c h a r a c t e r i s t i c s , and the s t r u c t u r a l r e l a t i o n s to c o u n t r y r o c k s o f t h e gabbros and the complexes. The g a b b r o - u l t r a m a f i c i n t r u s i o n s a r e shown to be s t r i k i n g l y s i m i l a r t o k o m a t i i t e s o f Precambrian t e r r a n e s . REGIONAL SETTING AND GEOLOGY OF QUILL CREEK AREA The Q u i l l Creek a r e a i s i n the Kluane Ranges o f the Yukon. I n f o r m a t i o n on r e g i o n a l s e t t i n g o f t h e Kluane Ranges and o t h e r p a r t s o f t h e S a i n t E l i a s F o l d B e l t i s found i n M u l l e r (1967), Campbell and Dodds (1978), and Read and Monger (1976). F i g u r e 1 i s a s i m p l i f i e d g e o l o g i c map o f the Q u i l l Creek a r e a . Lower Permian b a s a l t i c a n d e s i t e flows and p y r o c l a s t i c r o c k s o f the S t a t i o n Creek F o r m a t i o n , 1200 m t h i c k , form the o l d e s t exposed u n i t . Lower Permian s e d i m e n t a r y r o c k s o f t h e Hasen Creek F o r m a t i o n , 900 m t h i c k , c o n f o r m a b l y o v e r l i e t h e S t a t i o n Creek. ' Grey t o b l a c k s h a l e , a r g i l l i t e , c h e r t , and s i l t s t o n e a r e succeeded by s h a l y o r massive l i m e s t o n e , 57 F i g u r e 1. G e o l o g i c map o f the Q u i l l Creek a r e a , Kluane Ranges. L o c a t i o n o f the Kluane Ranges, the s t u d y a r e a s , and t e c t o n i c elements o f the southwest c o r n e r o f Yukon T e r r i t o r y a r e shown i n the i n s e r t . Kluane g a b b r o - u l t r a m a f i c complexes: ACnC=Arch Canyon Complex; ACkC=Arch Creek Complex; QCC=Quill Creek Complex; TCC=Tatamagouche Creek Complex; BCC=Burwash Creek Complex. 58 d i s c o n t i n u o u s reddish-brown c o n g l o m e r a t e s , and massive a r e n i t e s . Upper T r i a s s i c b a s a l t i c f l o w s o f t h e N i k o l a i G r e enstone, 1000 m t h i c k and d i s c o n f o r m a b l y o v e r t h e Hasen Creek s e d i m e n t a r y r o c k s , are i n t e r m e d i a t e between t h o l e i i t e s and b a s a l t i c k o m a t i i t e s (see C h a p t e r 2. T a b l e 4 ) . Kluane g a b b r o - u l t r a m a f i c complexes are conformable w i t h Lower Permian r o c k s . Maple Creek gabbro dykes and s i l l s i n t r u d e the S t a t i o n Creek and Hasen Creek F o r m a t i o n s , whereas dykes are more p r e v a l e n t i n the N i k o l a i G r e e n s t o n e . T h i s P e r m o - T r i a s s i c assemblage i s p r e s e r v e d i n t i g h t to l o c a l l y i s o c l i n a l f o l d s w i t h n o r t h w e s t axes. Numerous s u b p a r a l l e l f a u l t s a re t y p i c a l l y a l o n g o r c l o s e t o l i t h o l o g i c c o n t a c t s . Metamorphic grade i n the Kluane Ranges v a r i e s from p r e h n i t e - l a u m o n t i t e and p r e h n i t e - p u m p e l l y i t e f a c i e s i n N i k o l a i b a s a l t s t o lowermost g r e e n s c h i s t f a c i e s i n u n d e r l y i n g Hasen Creek s e d i m e n t a r y and S t a t i o n Creek v o l c a n i c r o c k s . KLUANE GABBRO-ULTRAMAFIC COMPLEXES I n t r o d u c t i o n Two types o f complexes are d i s t i n g u i s h e d . They o c c u r a t d i f f e r e n t s t r a t i g r a p h i c l e v e l s , 400 to 700 m a p a r t ( F i g u r e 2 ) . Complexes o f t h e Lower Group l i e w i t h i n S t a t i o n Creek Formation and i n c l u d e the Q u i l l Creek, Arch Creek, Arch Canyon, and White R i v e r complexes. P e r i d o t i t e i s the main rock t y p e . Gabbro o r o l i v i n e gabbro make up about 1 t o 2 p e r c e n t o f t h e s e complexes and w i t h one e x c e p t i o n o c c u r a t the s t r u c t u r a l base o f t h e p e r i d o t i t e . G a b b r o - p e r i d o t i t e complexes o f t h e Upper Group l i e i n Hasen Creek Formation and i n c l u d e Tatamagouche Creek and Burwash Creek complexes. 59 3000|-cn 2500 UJ oc t— ^ 2000 1500 1000 500 NW SE / V V V V V V V V V V V V V V V V V V V / v v v v v v v v v v v v v v v v v v \ . ' V V V V V V V V V V V V V V V V V V N i • v v v v v v v v v v v v v v v v v v v / V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V / V V V V V V V 7 7 V V V V V V V V V V V V V V V V V V 7 V V V V V V V V V V V V V V V V V V V V V V V V y v v v v v v v v v v w v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v • V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V • . ' V V ^ . ' W V V V V V V V V V V V V V V V , . BURWAST[;UN_ N A M E D E^ J^^ A^GOUCHECREEK^ r ~ S H ~ PPR|nmiTF_3m\\\\\\\\m A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A L V A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A ARCH CANYONVARCH t ^ V A V / / A ' A ' 'A' K'A' a'a r*AAA QUILL ' CREEK VA A A iTS™S A ' A A' A A A AAAAAAAAAAA „ RE.EK A"A"A"A* « - » - » - » - » - » - « - r M A V . A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A ' A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A Ac . A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A i . A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A /-^A,, A , A , A A | A A A A | A A A A -y A, ft ft-l^ 6 A ft ft I NIKOLAI GREENSTONE HASEN CREEK FMN. STATION CREEK FMN. GABBRO . A A A . . A A A A l ^ A A A AAA, OLIVINE GABBRO PERIDOTITE DUNITE SULPHIDES 1000 3000 metres 3000 2500 2000 1500 1000 500 F i g u r e 2. Schematic c r o s s s e c t i o n o f s t r a t i g r a p h i c p o s i t i o n s o f Kluane g a b b r o - u l t r a m a f i c complexes ( l o o k i n g n o r t h e a s t ) . White R i v e r complex l i e s some 100 km nor t h w e s t o f Q u i l l Creek complex. Dashed l i n e s be-tween complexes i n d i c a t e p r o b a b l e o r i g i n a l l y l a r g e r complexes. 60 Gabbro forms about o n e - t h i r d o f each complex and o c c u r s a t the s t r u c t u r a l top o f t h e p e r i d o t i t e u n i t . The Q u i l l Creek complex extends s o u t h e a s t from We 11 green Mine and i s t h e l a r g e s t body, b e i n g exposed o v e r an a r e a o f 8 km by 650 m (see F i g u r e 1 ) . Dunite i s up t o 100 m t h i c k and i s l i m i t e d t o the Well green a r e a . The o v e r l y i n g p e r i d o t i t e i s about 100 m t h i c k . S u l p h i d e - b e a r i n g gabbro, a v e r a g i n g about 10 m t h i c k , l i e s a t t h e base o f the p e r i d o t i t e n e a r the p e r i d o t i t e - d u n i t e c o n t a c t . The e x t r e m i t i e s o f the complex are i r r e g u l a r l y d i g i t a t e . T h i s d i g i t a t e n a t u r e , the o c c u r r e n c e o f minor f o l d s and opposed s t r a t i g r a p h i c tops i n the c o u n t r y r o c k s , and minor f o l d s i n f l o a t o f s c h i s t o s e p e r i d o t i t e s u g g e s t t h a t the complex i s f o l d e d and t h a t t h e exposed w i d t h i s much g r e a t e r than the t r u e t h i c k n e s s ( F i g u r e 3 ) . A s k e t c h o f t h e o r i g i n a l complex i s g i v e n i n F i g u r e 7. The A r c h Creek complex l i e s 4 km no r t h w e s t o f Well green Mine. I t i s 1 km by 100 m and i s on s t r i k e w i t h the Q u i l l Creek complex. I t c o n s i s t s o f p e r i d o t i t e w i t h minor s u l p h i d e - b e a r i n g o l i v i n e gabbro, 1 t o 2 m t h i c k , a t the base. The A r c h Canyon complex, 7.5 Km we s t - n o r t h w e s t o f Well green Mine, 1 km by 100 m, c o n s i s t s o f p e r i d o t i t e and, a t the base and t o p , o l i v i n e gabbro. The White R i v e r complex i s s i t u a t e d 97 km n o r t h w e s t o f the Q u i l l Creek a r e a . I t i s exposed o v e r a minimum l e n g t h o f 3.5 km and an approximate w i d t h o f 150 m and c o n s i s t s o f d u n i t e , p e r i d o t i t e , and gabbro. Minor s u l p h i d e - b e a r i n g o l i v i n e gabbro o c c u r s a t the e a s t e r n margin o f the p e r i d o t i t e . A l l c o n t a c t s a r e f a u l t e d and s l i c k e n s i d e s s u g g e s t movement i n more than one d i r e c t i o n . The w r i t e r c o n c l u d e s t h a t the complex i s now an assemblage o f f a u l t s l i v e r s . 61 S53 K51 L E G E N D NIKOLAI GREENSTONE GABBRO PERIDOTITE DUNITE HASEN CREEK FORMATION STATION CREEK FORMATION SULPHIDES PRIMARY LAYERING GEOLOGIC CONTACT FAULT , WITH DIP PROJECTED CONTACT CROSS SECTION A — A SW 5 0 0 0 r 4 0 0 0 3 0 0 0 NE V V ^ V » * / — " r v y * v W v " v » v v V. » CROSS SECTION B-B* F i g u r e 3. G e o l o g i c map and c r o s s s e c t i o n s o f the Well green p r o p e r t y , showing the d i g i t a t e n o r t h w e s t e x t r e m i t y o f the Q u i l l Creek gabbro-ul t r a m a f i c complex. 62 The Tatamagouche Creek complex i s 20 km s o u t h e a s t o f Well green Mine and t r e n d s n o r t h w e s t from n e a r the j u n c t i o n o f Tatamagouche and Burwash Creeks ( F i g u r e 1 ) . I t i s p o o r l y exposed but may measure as much as 5 km by 400 m. A p e r i d o t i t e u n i t , which i s r o u g h l y 250 m t h i c k , i s o v e r l a i n by gabbro, about 150 m t h i c k . Minor s u l p h i d e s a r e d i s s e m i n a t e d through the p e r i d o t i t e . The Burwash Creek complex i s 22 km s o u t h e a s t o f W e l l g r e e n Mine. T h i s n o r t h w e s t e r l y t r e n d i n g complex measures about 1 km by 200 m. P e r i d o t i t e i s 120 m t h i c k and i s o v e r l a i n by 60 m o f gabbro. Minor d i s s e m i n a t e d s u l p h i d e s o c c u r i n the p e r i d o t i t e . P e t r o g r a p h y Dunite i s p a l e green t o g r e y and a t White R i v e r has been s t r o n g l y s h e a r e d . In t h i n s e c t i o n the rock resembles a cumulate w i t h i n t e r c u m u l u s m a g n e t i t e , o r t h o p y r o x e n e , and " p l a g i o c l a s e " . 1 S e r p e n t i n e pseudomorphs a f t e r o l i v i n e c r y s t a l s , somewhat e l o n g a t e , c o n s t i t u t e 85 p e r c e n t o r more o f the r o c k . Orthopyroxene (now s e r p e n t i n e ) forms 1 t o 4 p e r c e n t , p l a g i o -c l a s e about 10 p e r c e n t , and p r i m a r y magnetite about 2 p e r c e n t . P e r i d o t i t e o f the Lower Group, i n d i s t i n g u i s h a b l e from t h a t o f the Upper Group complexes, i s massive t o s c h i s t o s e , medium-grained, and dark green to b l a c k . H a r z b u r g i t e , some o f i t showing cumulate t e x t u r e , c o n s i s t s o f 75 t o 85 p e r c e n t o l i v i n e and 5 to 10 p e r c e n t e n s t a t i t e . L h e r z o l i t e c o n t a i n s 50 t o 75 p e r c e n t o l i v i n e , 5 t o 10 p e r c e n t e n s t a t i t e , and 10 t o 20 p e r c e n t a u g i t e . W e h r i i t e c o n s i s t s o f 40 t o 70 p e r c e n t o l i v i n e , l e s s 1 M i c r o p r o b e a n a l y s e s o f a l t e r e d , p a r t l y i s o t r o p i c , i n t e r s t i t i a l m a t e r i a l i n d i c a t e a c o m p o s i t i o n s i m i l a r t o t h a t o f p l a g i o c l a s e (see T a b l e 1) and X-Ray D i f f r a c t i o n shows the presence o f e p i d o t e and h y d r o g r o s s -u l a r i t e . 63 than 10 p e r c e n t e n s t a t i t e , and 10 to 25 p e r c e n t a u g i t e . " P l a g i o c l a s e " amounts t o 10 to 20 p e r c e n t o f a l l p e r i d o t i t e t y p e s . Minor c o n s t i t u e n t s i n c l u d e p h l o g o p i t i c b i o t i t e and m a g n e t i t e . P e r i d o t i t e o f the Lower Group c o n t a i n s a maximum o f 10 p e r c e n t s u l p h i d e s by volume, whereas t h a t o f the Upper Group c o n t a i n s a maximum o f o n l y 2 p e r c e n t . Most o f the o l i v i n e and e n s t a t i t e a r e a l t e r e d t o s e r p e n t i n e and a u g i t e i s p a r t l y u r a l i t i z e d . P e r i d o t i t e c o n t a i n i n g f r e s h o l i v i n e and e n s t a t i t e i s r a r e , e x c e p t f o r a I h e r z o l i t e a t White R i v e r . M i c r o p r o b e a n a l y s e s o f m i n e r a l c o n s t i t u e n t s a re g i v e n i n T a b l e 1. O l i v i n e gabbro and gabbro o f the Lower Group a r e f i n e - to medium-g r a i n e d , dark g r e e n , and s t r o n g l y f r a c t u r e d and s h e a r e d . O l i v i n e gabbro c o n t a i n s 30 to 45 p e r c e n t o l i v i n e , 30 to 45 p e r c e n t a u g i t e , 5 t o 10 p e r c e n t h y p e r s t h e n e , and 20 to 25 p e r c e n t p l a g i o c l a s e , w i t h v a r i a b l e amounts o f ma g n e t i t e and s u l p h i d e s t h a t on the average t o t a l 5 p e r c e n t . O l i v i n e i s a l t e r e d t o s e r p e n t i n e , h y p e r s t h e n e i s s l i g h t l y s e r p e n t i n i z e d , p l a g i o c l a s e i s a l t e r e d t o s a u s s u r i t e , and a u g i t e i s s l i g h t l y u r a l i t i z e d . Gabbro con-s i s t s o f 40 t o 75 p e r c e n t a u g i t e and 10 t o 35 p e r c e n t p l a g i o c l a s e w i t h up to 10 p e r c e n t h y p e r s t h e n e and 1 t o 10 p e r c e n t o l i v i n e . P l a g i o c l a s e i s about An^g. M a g n e t i t e and s u l p h i d e s range from 1 t o 8 p e r c e n t and 5 to 30 p e r -c e n t , r e s p e c t i v e l y . A l t e r a t i o n resembles t h a t o f the o l i v i n e gabbro. M a s s i v e t o n e a r - m a s s i v e s u l p h i d e s o c c u r a t the f o o t w a l l o f both t he o l i v i n e gabbro and gabbro and a r e succeeded upwards by n e t - t e x t u r e d s u l -p h i d e s , and f i n a l l y by d i s s e m i n a t e d s u l p h i d e s . T h i s sequence s t r o n g l y s u g g e s t s t h a t the o r i g i n a l top o f both the o l i v i n e gabbro and gabbro i s toward the base o f the o v e r l y i n g p e r i d o t i t e . Gabbro o f the Upper Group c o n s i s t s o f 30 t o 45 p e r c e n t a u g i t e , 30 t o 60 p e r c e n t p l a g i o c l a s e ( A n R R _ f i n ) , up to 15 p e r c e n t o l i v i n e , and up t o 64 TABLE 1. Average m i c r o p r o b e a n a l y s i s f o r o l i v i n e , e n s t a t i t e , a u g i t e , p h l o g o p i t i c b i o t i t e , and " p l a g i o c l a s e " i n I h e r z o l i t e , White R i v e r complex. Oxi de O l i v i n e 3 E n s t a t i t e b A u g i t e 0 B i o t i t e d " P l a g i o c l a s e " e S i 39.05 55.87 52.33 38.78 40. ,79 T i .05 .55 .73 4.42 ,05 Al .02 1 .08 2.54 14.85 25, .70 Fe 15.34 9.50 4.71 5.92 7, .72 Mn .20 .21 .13 .01 .51 Mg 45.57 31.49 17.82 20.38 1. .35 Ca .09 1.48 20.30 20, .14 Na .01 .03 .23 .91 .48 K .02 .03 .02 8.70 2 .94 T o t a l 100.35 100.24 98.81 93.97 99 .68 a Fo c o n t e n t i s 83 t o 85 p e r c e n t ; average o f 6 a n a l y s e s b Average o f 12 a n a l y s e s c Average o f 8 a n a l y s e s d Average o f 4 a n a l y s e s e Average o f 7 a n a l y s e s ; CIPW norms i n d i c a t e about 60 p e r c e n t a n o r t h i t e , 10 p e r c e n t c a l c i u m o r t h o s i 1 i c a t e , 10 p e r c e n t l e u c i t e , and 8 p e r c e n t m a g n e t i t e , w i t h the r e m a i n i n g 12 p e r c e n t d i v i d e d e q u a l l y among o r t h o c l a s e , n e p h e l i n e , d i o p s i d e , o l i v i n e , w o l l a s t o n i t e , and k a l i o p h i l i t e ; X-ray d i f f r a c t i o n shows the presence o f h y d r o g r o s s u l a r i t e and e p i d o t e . 65 10 p e r c e n t h y p e r s t h e n e . A c c e s s o r y m i n e r a l s a r e m a g n e t i t e and s u l p h i d e s , which amount t o about 1 p e r c e n t each. A l t e r a t i o n resembles t h a t d e s c r i b e d above. D i f f e r e n c e s between the Lower and Upper Group complexes a r e as f o l l o w s . Complexes o f t h e Lower Group c o n s i s t p a r t l y o f d u n i t e , whereas d u n i t e i s l a c k i n g i n those o f t h e Upper Group. P e r i d o t i t e o f t h e Lower Group has a g r e a t e r amount o f d i s s e m i n a t e d s u l p h i d e s than t h a t o f the Upper Group. Lower Group complexes c o n t a i n b a s a l gabbro and o l i v i n e gabbro (e x c e p t f o r Arch Canyon complex, which c o n t a i n s o l i v i n e gabbro both above and below the p e r i d o t i t e ) , whereas gabbro o f the Upper Group o v e r l i e s p e r i d o t i t e . The pyroxene t o p l a g i o c l a s e r a t i o s t e n d t o be h i g h e r i n the Lower Group gabbro. S u l p h i d e s a r e abundant i n the gabbro ( e x c e p t a t White R i v e r ) and i n the o l i v i n e gabbro o f the Lower Group but i n s i g n i f i c a n t i n gabbro o f t h e Upper Group. C h e m i s t r y S i n c e i t i s argued below t h a t t h e Kluane g a b b r o - u l t r a m a f i c complexes a r e k o m a t i i t i c , a b r i e f d e s c r i p t i o n o f k o m a t i i t i c r o c k s f o l l o w s . K o m a t i i t e s form a s e r i e s o f u l t r a b a s i c and b a s i c r o c k s w i t h low T i ^ f o r a g i v e n MgO, low Fe/Mg r a t i o s f o r a g i v e n A ^ O ^ and CaO/A^O^ r a t i o s about equal t o one, h i g h MgO, h i g h N i , and high C r . They d i f f e r from n e a r l y a l l a l p i n e u l t r a m a f i c r o c k s i n the p r e s e n c e o f p l a g i o c l a s e and from u l t r a m a f i c r o c k s o f l a y e r e d i n t r u s i o n s by h i g h e r MgO, l o w e r T ^ , and lower a l k a l i e s . Three t y p e s o f k o m a t i i t e s a r e r e c o g n i z e d i n the Canadian S h i e l d and elsewhere - p e r i d o t i t i c , p y r o x e n i t i c , and b a s a l t i c ( A r n d t e_t a l _ . , 1977). There may e x i s t , i n any one a r e a , a complete range i n c h e m i s t r y between b a s a l t i c k o m a t i i t e t h r o u g h an i n t e r m e d i a t e type t o t h o l e i i t i c b a s a l t ( N a l d r e t t and T u r n e r , 1977). P e r i d o t i t i c k o m a t i i t e s have MgO g e n e r a l l y 66 g r e a t e r than 30 p e r c e n t and i n v a r i a b l y g r e a t e r than 20 p e r c e n t ; p y r o x e n i t i c k o m a t i i t e s have MgO between 12 and 20 p e r c e n t ; and b a s a l t i c k o m a t i i t e s have MgO l e s s than 12 p e r c e n t . N a l d r e t t and T u r n e r (1977) s u b - d i v i d e p e r i d o t i t i c k o m a t i i t e s from Y a k a b i n d i e , Western A u s t r a l i a , i n t o p e r i d o t i t i c w i t h g r e a t e r than 30 p e r c e n t MgO, and pyroxene p e r i d o t i t i c w i t h 20 t o 30 p e r c e n t MgO. The f i e l d s o f k o m a t i i t e c o m p o s i t i o n s a r e shown i n F i g u r e 4. The compositions"'' o f Kluane complexes f a l l w i t h i n o r c l o s e t o the f i e l d s o f t h e O n t a r i o k o m a t i i t e s ( F i g u r e 4 ) , s u g g e s t i n g t h a t t h e y b e l o n g t o the k o m a t i i t e f a m i l y . The d i s t i n c t i o n i s n o t so c l e a r f o r Maple Creek gabbros. A s e a r c h o f rock a n a l y s e s has r e v e a l e d o n l y one o t h e r group o f common igneous rocks t h a t f i t the chemical c r i t e r i a f o r k o m a t i i t e s - thes e are the cumulate r o c k s o f o p h i o l i t e sequences (Coleman, 1977), many o f which p l o t w e l l w i t h i n the k o m a t i i t e f i e l d s o f F i g u r e 4. The Kluane complexes (and cumulate o p h i o l i t e r o c k s ) do not show s p i n i f e x t e x t u r e , but t h i s l a c k cannot be c o n s i d e r e d a d i s q u a l i f y i n g c r i t e r i o n s i n c e i t s p r e s e n c e depends o n l y on c h i l l i n g i n a s u r f a c e o r n e a r s u r f a c e environment. Kluane complexes a r e s t r u c t u r a l l y s i m i l a r t o the l e s s common i n t r u s i v e k o m a t i i t e s . With MgO c o n t e n t s o f 43 to 46 p e r c e n t ( T a b l e 2 ) , d u n i t e f a l l s i n the hig h MgO r e g i o n o f p e r i d o t i t i c k o m a t i i t e s . Normative a n o r t h i t e i s low and no r m a t i v e f e l d s p a r i s g e n e r a l l y l e s s than 8 p e r c e n t . P e r i d o t i t e f a l l s i n t o the p e r i d o t i t i c k o m a t i i t e c a t e g o r y . Normative f e l d s p a r ranges from 8 t o 17 p e r c e n t . O l i v i n e gabbro o f t h e Lower Group complexes has the 1 A n a l y s e s ( T a b l e s 2 and 3) show L.0.1. v a l u e s up t o 12.8 p e r c e n t . These high v a l u e s a r e l a r g e l y due t o the presence o f s e r p e n t i n e (see Ar n d t e t a l _ . , 1977. T a b l e 7 ) . I t i s assumed t h a t the d i a g n o s t i c r a t i o s a r e l i t t l e a f f e c t e d by s e r p e n t i n i z a t i o n . 67 F i g u r e 4. Chemical f i e l d s f o r Kluane complexes, Maple Creek gabbros, and N i k o l a i Greenstone b a s a l t s . Chemical f i e l d s f o r Munro Township koma-t i i t e s a r e from Arndt (1977) and A r n d t et_ a l . (1977), t h o s e f o r Yaka-b i n d i e k o m a t i i t e s from N a l d r e t t and C a b r i (T976) and N a l d r e t t and T u r n e r (1977), and t h o s e f o r k o m a t i i t e s i n g e n e r a l from N a l d r e t t and Goodwin (1977). 68 TABLE. 2. Whole rock c h e m i s t r y , CIPU norms, and t r a c e e lement data f o r K luane u l t r a m a f i c r o c k s . UPPER GROUP LOWER GROUP BCC TCC ACnC ACkC OCC WRC OXIDE H 136-6 W 1052 L. 193-1 L. 1113-2 D 230-1 D 232-1 252-1 W 254-1 w 256-1 H-L 258-1 w 260-1 L 262-1 D 292-1 0 253-1 294-1 S i O j 4 1 . 0 39 .8 40 .0 25.5 37 .0 38 .0 37 .5 37 .8 37 .5 38 .0 38 .0 36.0 4 2 . 0 T i O j .25 .45 .38 .46 .14 .13 .32 .23 .27 .29 .23 .17 .12 .16 .48 A U 0 3 2 . 7 3.8 3.2 4 . 7 1.3 1.3 4.1 2 . 7 2 .3 2 .8 2.1 1.9 1.2 1.7 3 .8 F e T a 12 .8 11 .4 n ' .s 8.4 8 .0 12 .0 13 .4 9 .5 11.1 10.1 5.6 6 .8 ' 7.9 12 .9 MnO .17 .14 .14 .14 .13 .12 .12 .14 .13 .12 .11 .14 .16 MgO 39 23 25 31 40 39 33 35 39 38 38 37 38 38 25 CaO 1 .6 3 .3 2 . 8 2.1 .6 .3 2 .2 2 . 7 .60 1 .4 .9 .4 .6 1.7 3.6 .Na.O L .69 .64 .59 .58 .57 .59 .59 .52 .54 .56 .58 .57 .71 .41 .37 .32 .29 .21 .29 .26 .27 .28 .28 .23 .27 .67 F 2 ° 5 .27 .29 .30 .33 .17 .27 .18 .18 .61 .18 .16 .16 .28 L . O . I . 4 .2 7.1 9.1 12 .2 1 1 . 3 7.5 7.1 9.4 6 .4 10.1 12 .8 11 .6 2 .6 S .2 .1 .3 .3 .2 .9 .7 .4 .8 .6 .1 .1 .2 T o t a l 101 .29 101.22 100.51 9 9 . 7 8 98.31 99 .29 100 .48 100.38 99 .85 101.07 98 .7 98 .3 102.4 O r t h . 2 .54 2 .36 2 .08 1.97 1.45 1.93 1.67 1 .78 1.8 1 .83 1 .57 1.88 4 .03 A l b i t e 6 .09 £ . 8 4 5 .54 1.41 5.64 5 .52 1.85 4 .94 4 .97 5 .32 5.79 1.5 4 .88 A n o r . 6.41 5 .0 9.41 .16 .46 8 .63 4 .25 1 .S8 3 .17 2 .53 .05 1.39 5 .26 Di o p . 6 . S 7 6 .23 .63 1.26 7.11 .89 1.81 5 .58 8 .73 H y p e r . ' 4 . 4 5 2 .13 19 .35 4 . 1 8 5 .15 3 .63 .97 3.34 10.61 Magnet . 1 .88 1.6 1.67 1.27 1.22 1 .74 1.91 1.38 1.59 1.47 1.04 1.2 1.71 A p a t . .65 .72 .77 .89 .45 .69 .47 .47 1.55 .46 .43 .43 .66 I l m e n . .89 .78 .97 .31 .29 .68 .48 .57 .6 .49 .27 .35 .92 01 i v . 70.21 75.34 59 .88 91 .08 86.31 74.4 8 0 . 3 84 .74 84.77 83.66 78.44 85 .43 73.14 Neph. 2 . 3 1.96 2 .24 .66 C o r u n . .33 .01 .5 .58 Mg/ (Mo+f e) b 84 .8 8 7 . 7 36.4 9 1 . 5 91 .7 86.4 85 .7 90 .5 8 8 . 7 8 9 . 7 9 2 . 7 91 .6 86.4 Cu 208 350 152 340 100 90 1410 I960 460 1250 220 380 20 20 168 Ni 1660 1310 2080 1890 1850 2350 2900 2400 2200 3550 2030 1540 2380 2110 2050 Co 64 70 71 60 71 48 66 48 61 70 52 60 56 56 70 Cr 2600 3000 2800 3100 2000 , 3000 2800 3600 3000 2300 2200 1800 2600 2300 3800 Zn 71 83 76 70 72 41 79 82 79 81 • 56 28 47 46 85 Ba 7 45 57 19 0 0 15 14 4 6 2 0 8 9 122 S r 6 60 47 13 3 1 9 5 3 4 4 2 3 5 64 Rb 6 5 4 5 0 0 4 1 1 1 1 1 0 1 10 Nb 5 ' 5 6 6 5 3 5 4 5 5 5 6 4 4 7 IT 23 35 34 45 18 17 29 22 28 27 23 20 15 19 Y 8 10 9 11 6 6 9 7 9 •9 7 7 5 7 n a As F e j O j b In s i l i c a t e s A b b r e v i a t i o n s : H •= h a r z b u r g i t e ; W * w e h r i i t e ; L • l h e r e o l i t e ; D • d u n i t e ; 6CC - Curwash C r e e k ; TCC » Tatamagouche C r e e k ; ACnC ' A r c h C a n y o n ; ACkC = A r c h C r e e k ; QCC « Q u i l l C r e e k ; WRC = White R i v e r . 69 h i g h MgO and low a l k a l i e s c h a r a c t e r i s t i c o f p e r i d o t i t i c k o m a t i i t e s o r , more s p e c i f i c a l l y , t he pyroxene p e r i d o t i t i c k o m a t i i t e s as d e f i n e d by N a l d r e t t and T u r n e r (1977). Gabbros from White R i v e r complex and from the Upper Group complexes a r e p y r o x e n i t i c k o m a t i i t e s ( T a b l e 3 ) . S t r u c t u r e The r e l a t i o n o f o l i v i n e gabbro and gabbro t o the u l t r a m a f i c p a r t o f t h e Lower Group complexes i s n o t c l e a r . In the Q u i l l Creek complex gabbro o c c u r s o n l y a t the W e l l g r e e n P r o p e r t y , where i t l i e s a t t h e base o f t h e complex n o r t h e a s t o f t h e p e r i d o t i t e - d u n i t e c o n t a c t . The gabbro i s i n f a u l t c o n t a c t w i t h p e r i d o t i t e and ranges i n t h i c k n e s s from 5 t o 40 m w i t h an average o f 10 m. F i g u r e 5 i s a somewhat diagrammatic c r o s s s e c t i o n i l l u s t r a t i n g i t s s t r u c t u r a l r e l a t i o n s h i p s . O l i v i n e gabbro a t L i n d a Creek ( p a r t o f t h e Q u i l l Creek complex) and i n the Arch Creek and White R i v e r complexes appears t o occupy about 5 p e r c e n t o f t h e n o r t h w e s t - t r e n d i n g l e n g t h o f t h e p e r i d o t i t e f o o t w a l l . The o l i v i n e gabbro i s l e s s than 5 m t h i c k and t h e c o n t a c t w i t h p e r i d o t i t e i s s h e a r e d . R e l a t i o n s between the o l i v i n e gabbro and p e r i d o t i t e a re s i m i l a r t o t h o s e at W e l l g r e e n , e x c e p t t h a t s u l p h i d e s a r e l e s s abundant and the massive s u l p h i d e pods a r e much s m a l l e r . O l i v i n e gabbro a t the top and base o f t h e Arch Canyon complex i s a l s o d i s c o n t i n u o u s a l o n g s t r i k e , o c c u p y i n g r o u g h l y 15 p e r c e n t o f the i n t r u s i v e body. L a y e r i n g i n the Lower Group complexes cannot be seen i n the f i e l d , but i s r e v e a l e d by t h i n s e c t i o n s t u d y . Dunite u n d e r l i e s p e r i d o t i t e , but the c o n t a c t i s n o t exposed. A s t u d y o f specimens c o l l e c t e d a c r o s s the p e r i d o t i t e i n Q u i l l Creek and Arch Canyon complexes ( F i g u r e 6) s u g g e s t s z o n i n g from the upper and lower c o n t a c t s inwards o f o l i v i n e gabbro t o w e h r i i t e t o I h e r z o l i t e . 70 TABLE 3. Whole rock c h e m i s t r y , CIPW norms, and t r a c e element data f o r o l i v i n e gabbro and gabbro i n Kluane complexes. Gabbro o f O l i v i n e Gabbro o f Lower Group Gabbro o f Lower Group Upper Group ACnC ACkC Q u i l l Creek Q u i l l Creek WRC TCC BCC Oxide 192-1 1101-6 1021-5 1120-9 1122-3 1127-7 288-1 38-1 1 36-i S i 0 2 39.5 38.0 41.3 47.0 44.0 T i 0 2 .73 .60 .60 .55 .39 .44 .5' A 1 2 0 3 6.0 5.9 7.0 7.7 12.3 13.4 12.9 FeT a 13.7 14.3 12.4 10.5 12.0 MnO .15 .16 .13 .13 .13 MgO 26.0 25.1 26.3 25.5 14.3 14.4 8.3 CaO 6.5 8.7 3.2 6.5 9.5 11.3 7.3 Na 20 .78 .69 .60 1.6 1.6 K 20 .43 .47 .29 1.1 4.9 P2°5 • .41 .72 .28 .17 .12 L.O.I. 4.8 5.1 5.3 2.8 1.7 S .2 .7 .3 1.1 .0 TOTAL: 99.20 100.44 97.70 99.89 99.58 Ort h . 2.71 2.89 1.9 6.57 3.0 A l b i t e 5.17 6.54 5.6 13.68 3.52 Anor. 12.43 13.02 15.42 24.48 28.86 Di op. 15.28 11.28 18.89 22.79 Hyper. 7.94 28.27 9.78 Magnet. 2.56 2.40 2.38 1 .9 2.15 A p a t i t e 1.02 1 .73 .72 .42 .28 Ilmen. 1 .49 1.26 1.26 .77 .77 O l i v i n e 58.31 52.94 43.89 23.51 30.8 Neph. 1 .04 2.83 Corun. .57 Mg/(Mg+Fe) i n Si 1 i c a t e s 82.7 81 .2 84.0 76.9 74.6 Cu . 250 1200 480 70 5200 6500 3100 40 158 Ni 980 2550 1110 368 5430 33400 4330 360 118 Co 74 88 67 58 136 510 142 45 40 Cr 3200 2400 2300 1200 9000 4300 780 1400 520 Zn 81 82 62 69 135 67 53 64 95 Ba 71 76 5 451 7 8 25 58 965 Sr 91 30 52 179 . 11 14 37 168 436 Rb 7 7 2 23 1 1 2 6 23 Nb 7 7 6 4 5 4 6 4 6 Zr 58 43 51 22 49 16 52 32 78 Y 14 12 14 11 13 8 13 12 21 3, As F e 2 0 3 A b b r e v i a t i o n s : 8CC = Burwash Creek; TCC = Tatamagouche Creek; ACnC = Arch Canyon; ACkC = Arch Creek; WRC = White R i v e r . 71 SW l+vH GABBRO KV-I PERIDOTITE DISSEMINATED SULPHIDES NET-TEXTURED SULPHIDES / V "T/ X - ' l ' MASSIVE SULPHIDES BEDDING IN ARGILLITE / ,\ •>> , )iMM HORNFELS / -1 \ ' ' ARGIltlTE . ^ ^ i f ; ^ \ 1 ( C R O S S S E C T I O N L O O K I N G N W ) Fi g u r e 5 . Cross s e c t i o n o f s t r u c t u r a l r e l a t i o n s among gabbro, p e r i d o t i t e , and s u l p h i d e ore types a t W e l l g r e e n Mine, c o m p i l e d from s u r f a c e mapping and underground i n f o r m a t i o n . 72 A, yr 1 ?f 7 ^ r r 7 7 r 50 40* to ^ « 30 20 10 OLIVINE CLINOPYROXENE::.:: PLAGIOCLASE 20% • 1 SULPHIDES 1 ORTHOPYROXENE ( a ) 1 1 OL IV INE G A B B R O fc&tl WEHRLITE L H E R Z O L I T E 120 100 80 £ 6 0 LU (— w LU 40 20 0 ORTHOPYROXENE OLIVINE 20% i i PLAGIOCLASE • CLINOPYROXENE I II (b) F i g u r e 6. Cross s e c t i o n s showing modes f o r Q u i l l Creek complex ( a ) , and f o r Arch Canyon complex ( b ) . The c r o s s s e c t i o n f o r Q u i l l Creek r e p r e s e n t s a t l e a s t the lower 50 m o f a 100 m t h i c k n e s s . 73 Small i n c l u s i o n s o f t u f f , a few meters a c r o s s , a r e h o r n f e l s e d and c o n s i s t o f pyroxene and p l a g i o c l a s e . At the W e l l g r e e n P r o p e r t y h o r n f e l s c o n s i s t i n g o f p l a g i o c l a s e and pyroxene o c c u r s l o c a l l y a t the b a s a l t i c a n d e s i t e t u f f - p e r i d o t i t e c o n t a c t and h o r n f e l s c o n s i s t i n g o f h o r n b l e n d e , p l a g i o c l a s e , and minor pyroxene i s p r e s e n t a t t h e c h e r t y a r g i l l i t e - s u l p h i d e c o n t a c t s . Gabbro o f t h e Upper Group complexes i s s t r u c t u r a l l y above the p e r i d o t i t e and d e t a i l s o f t h e c o n t a c t a r e d i f f i c u l t t o see. In the Burwash Creek complex a 0.5 m wide zone a t t h e base o f the gabbro c o n t a i n s rounded i n c l u s i o n s o f p e r i d o t i t e and t h e p e r i d o t i t e appears to p e n e t r a t e t h e gabbro. These f e a t u r e s s u g g e s t t h a t n e i t h e r rock was s o l i d a t t h e time the boundary was formed. D i f f e r e n t i a t i o n o f a l i q u i d above an a c c u m u l a t i n g c r y s t a l mush and subsequent minor d e f o r m a t i o n o r slumping d u r i n g s o l i d i f i c a t i o n c o u l d account f o r t h e s e f e a t u r e s . The p e r i d o t i t e appears u n l a y e r e d i n the f i e l d , b u t a s t u d y o f a s u i t e o f specimens o f t h e Burwash Creek complex s u g g e s t s t h a t t h e r e i s an upwards change from I h e r z o l i t e t o w e h r i i t e . A t h i n basal w e h r i i t e u n i t i s n o t as pronounced as i t i s i n the Lower Group complexes. Al t e r a t i o n A l l u l t r a m a f i c r o c k s a r e s t r o n g l y s e r p e n t i n i z e d . L o c a l l y , t a l c -m agnesite v e i n s o c c u r a l o n g p e r i d o t i t e b o r d e r s . D i s c o n t i n u o u s , g r e e n i s h -w h i t e zones o f r o d i n g i t e , up t o 1 m wide, a r e found a l o n g p e r i d o t i t e -c o u n t r y rock c o n t a c t s . M i n e r a l assemblages i n c l u d e : i d o c r a s e - c a l c i t e + e p i d o t e ; i d o c r a s e - e p i d o t e + d i o p s i d e ; and d i o p s i d e - c a l c i t e - h y d r o g a r n e t -t r e m o l i t e + C r m u s c o v i t e ( o r m a r i p o s i t e ) . A l s o a l o n g t he sh e a r e d c o n t a c t s a r e d i s c o n t i n u o u s q u a r t z - c a r b o n a t e zones which c o n s i s t o f q u a r t z v e i n s , m a g n e s i t e , and i n some p l a c e s m a r i p o s i t e . 74 Age o f t h e Complexes Potassium-argon age dates were o b t a i n e d on p r i m a r y p a l e brown p h l o g o p i t i c b i o t i t e i n p e r i d o t i t e . Dates f o r the White R i v e r and Tatamagouche Creek complexes a r e i n d i s t i n g u i s h a b l e , a t 225+7 Ma and 224+8 Ma (Lower T r i a s s i c ) , r e s p e c t i v e l y ( T a b l e 4 ) . The Q u i l l Creek complex has been dated a t 421+9 Ma ( S i l u r i a n ) ( L a n p h e r e , w r i t t e n comm., 1976). S i n c e the Q u i l l Creek complex i n t r u d e s t h e S t a t i o n Creek F o r m a t i o n o f Lower Permian age t h e date cannot be a c c e p t e d . O r i g i n I t seems c l e a r t h a t complexes o f both the Lower and Upper Groups a r e s i l l - l i k e i n t r u s i o n s . ' S i m i l a r i t i e s i n p e t r o g r a p h y and c h e m i s t r y o f the Q u i l l Creek, Arch Creek, and Arch Canyon complexes s u g g e s t t h a t they a r e g e n e t i c a l l y r e l a t e d . The f a c t t h a t t h e y o c c u r a l o n g s t r i k e from one a n o t h e r s u g g e s t s they may be p a r t o f one l a r g e r complex, now dismembered by f o l d i n g and f a u l t i n g and subsequent e r o s i o n . F i g u r e 7a shows a s c h e m a t i c r e c o n s t r u c -t i o n o f t h e o r i g i n a l complex. Tatamagouche Creek and Burwash Creek complexes a l s o may be p a r t o f one complex, which has been r e p e a t e d by f o l d i n g . Complexes o f the Upper Group appear t o be d i f f e r e n t i a t e d k o m a t i i t i c complexes. They c o n s i s t o f p e r i d o t i t i c k o m a t i i t e o v e r l a i n by gabbro o f p y r o x e n i t i c k o m a t i i t e c o m p o s i t i o n . The w r i t e r c o n c l u d e s t h a t the p e r i d o t i t e formed m a i n l y by a c c u m u l a t i o n o f o l i v i n e and two pyroxenes, a f t e r which t h e o v e r l y i n g m e l t c r y s t a l l i z e d t o form the gabbro. F i g u r e 8a i s a c r o s s s e c t i o n showing modes and rock types o f the Burwash Creek complex. S i m i l a r i t y t o the 120 m t h i c k k o m a t i i t i c Fred's Flow o f Munro Township ( F i g u r e 8b) ( A r n d t e t a l _ . , 1977) i s s t r i k i n g . 75 TABLE 4. Potassium-argon age d e t e r m i n a t i o n s on p h l o g o p i t i c b i o t i t e i n Kluane g a b b r o - u l t r a m a f i c complexes. COMPLEX SAMPLE LOCATION 4 0 K / 3 9 A r AGE Tatamagouche North o f j u n c t i o n o f 224+8 Ma a Creek Burwash and Tatamagouche Creeks Q u i l l Creek South o f s u r f a c e exposures 421+9 Ma b o f massive Ni-Cu s u l p h i d e , W e l l g r e e n Mine White R i v e r Approx. 91 m s o u t h o f 225+7 Ma b Canalask a d i t on SE bank o f White R i v e r a J.E. H a r a k a l , Geophysics Department, U.B.C. Decay c o n s t a n t s : 4.96/.581/1.167 K = 5.45 5.41 (+0.7%) A r 4 0 = 5 0 . 4 3 3 x l 0 " 6 c c / g ( 2 2 . 5 0 5 x l 0 " 1 0 m o l / g ) 91.3% A r 4 0 b M. Lanphere, U.S.G.S. N.W. ARCH CANYON COMPLEX 100. A - / i ~~ A R C H CREEK COMPLEX WELLGREEN MINE LINDA CREEK 1 5.E. QUILL CREEK COMPLEX HYPOTHETICAL FEEDER AREA ,1000m sw NE PLANE A-B f V V l GABBRO X PROJECTION OF GABBRO AND SULPHIDE ORE OLIVINE GABBRO A N D PERIDOTITE (<50% OLIVINE) fr) \A\ PERIDOTITE (>50% OLIVINE) DUNITE l&Sfrl CUMULATE Z O N E III SULPHIDE ORE + + + + + + + + + + + + + +• ^ + + + + + + + + + + + ++ + +"• + + + + + + +" ~ + + + JRON-Q^jDE tRICH^G^BjRqj+^+; PYROXENITE 0.4 km (d) F i g u r e 7. Schematic r e c o n s t r u c t i o n o f p o s s i b l e o r i g i n a l Q u i l l Creek - Arch Creek - Arch Canyon complex ( a ) . H y p o t h e t i c a l examples (b) a f t e r N a l d r e t t (1973) and (c) a f t e r Usselman e t al_. (1979) and the t h o l e i i t i c Dundonald s i l l (d) a f t e r N a l d r e t t (1972) are i n c l u d e d f o r comparison. cn 77 + + + + + + r» J A > > A f •A T L A V4| / -' 100 2 0 % 1 O L I V I N E O R T H O P Y R O X E N E C U N O P Y R O X E N E +++| G A B B R O W E H R L I T E I H E R Z O L I T E F L O W - T O P B R E C C I A |II\\\|||T| S P I N I F E X 111 P Y R O X E N E C U M U L A T E O L I V I N E C U M U L A T E B O R D E R Z O N E O r 00 an U J OJ 100 C L I N O P Y R O X E N E O R T H O P Y R O X E N E ( i " t " ^ C H R 0 207. C H L O R I T E u b F i g u r e 8. (a) Cross s e c t i o n o f rock types and modal v a r i a t i o n i n the Burwash Creek complex, (b) Cross s e c t i o n o f Fred's Flow i s i n c l u d e d f o r comparison ( A f t e r A r n d t , 1977). 78 The o r i g i n o f t h e Lower Group complexes p r e s e n t s problems which, a t p r e s e n t , cannot be r e s o l v e d . Two hypotheses a r e c o n s i d e r e d . In t h e f i r s t , t h e u l t r a m a f i c r o c k s , o l i v i n e gabbro, and gabbro were formed d u r i n g a s i n g l e e p i s o d e o f d i f f e r e n t i a t i o n . That t he gabbro and o l i v i n e gabbro l i e below the p e r i d o t i t e ( w i t h one e x c e p t i o n ) seems to r u l e out f r a c t i o n a l c r y s t a l l i z a t i o n . I t i s c o n c e i v a b l e t h a t the p a r e n t c r y s t a l l i z i n g magma a c q u i r e d , by flo w d i f f e r e n t i a t i o n (see Gibb, 1968; B h a t t a c h a r j i , 1967) d u r i n g emplacement, a t h i n lo w e r and upper b o r d e r o f " g a b b r o i c " l i q u i d (now o l i v i n e gabbro and gabbro) and a t h i c k c e n t r a l zone o f o l i v i n e c r y s t a l s and l i q u i d (now p e r i d o t i t e ) . T h i s h y p o t h e s i s i s b e s e t by one major d i f f i c u l t y . Why i s one p a r t o f t h e b o r d e r zone o l i v i n e - r i c h ( o l i v i n e gabbro, about 40 p e r c e n t o l i v i n e ) and a n o t h e r p a r t o l i v i n e - p o o r (gabbro, up t o 10 p e r c e n t o l i v i n e ) ? I t i s s u g g e s t e d t h a t t h e r e l a t i v e l y s m a l l body o f d u n i t e r e p r e s e n t s t he a r e a n e a r a f e e d e r (see F i g u r e 7 ) . Gabbro i s i n p r o x i m i t y t o the d u n i t e , w h i l e o l i v i n e gabbro o c c u r s f a r t h e r away from the d u n i t e . A s t r o n g and more p e r s i s t e n t l a t e r a l f l o w would be e x p e c t e d n e a r e r the f e e d e r and t h i s f l o w would be e x p e c t e d t o de c r e a s e and be r e l a t i v e l y s h o r t - l i v e d as the magma flo w e d outward. The h i g h e r flow v e l o c i t y would ten d t o be more e f f e c t i v e i n removing o l i v i n e c r y s t a l s from the b o r d e r zone gabbro, w h i l e a weaker f l o w r a t e a t some d i s t a n c e from t he c o n d u i t would a l l o w a g r e a t e r p r o p o r t i o n o f o l i v i n e c r y s t a l s t o remain i n the margins. The c o m p o s i t i o n o f t h e gabbro i s s i m i l a r t o t h a t o f the o l i v i n e gabbro from which 40 p e r c e n t o l i v i n e has been removed. T h i s perhaps c o u l d e x p l a i n the d i s t r i b u t i o n o f gabbro and o l i v i n e gabbro. A second h y p o t h e s i s i s t h a t t h e o l i v i n e gabbro and u l t r a m a f i c r o c k s a r e p a r t o f a s i n g l e s t a g e i n t r u s i o n , but t h a t t he Well green 79 gabbro i s a s e p a r a t e and l a t e r i n t r u s i o n . I t appears p o s s i b l e t h a t t he gabbro a t Well green b e l o n g s t o a group o f y o u n g e r gabbros r e f e r r e d t o as t h e Maple Creek gabbros (see l a t e r s e c t i o n ) and was i n t r u d e d a l o n g the base o f the p e r i d o t i t e a t the p e r i d o t i t e - o r e c o n t a c t . T e x t u r e s s u g g e s t p a r t i a l m e l t i n g o f the o r e and i n c o r p o r a t i o n o f s u l p h i d e s by t h e gabbro. D.P. P r i c e , i n a company r e p o r t on the s t r u c t u r a l geology i n Well green Mine, mentions t h a t n e a r the bottom o f the ore body the gabbro seems t o c o n t i n u e down plunge and becomes t h i c k e r . An exposure i n t h e L i n d a Creek a r e a shows Maple Creek dykes i n t r u d i n g a l o n g f r a c t u r e s i n t h e Q u i l l Creek p e r i d o t i t e . F i n a l l y , Zn, Ba, S r , Rb and Zr c o n t e n t s o f t h e gabbro a t Well green and White R i v e r c o v e r a w i d e r range than those o f t h e o l i v i n e gabbro ( T a b l e 3) - a range more i n k e e p i n g w i t h t h e range f o r t h o s e same t r a c e elements i n the Maple Creek gabbros. S u l p h i d e s i n the gabbro, however, show the same l a y e r i n g as s u l p h i d e s i n t h e o l i v i n e gabbro and i n magmatic d e p o s i t s i n g e n e r a l . C o n c e i v a b l y , gabbro i n t r u d i n g a l o n g t h e p e r i d o t i t e - o r e c o n t a c t would i n c o r p o r a t e m e l t e d s u l p h i d e s as i m m i s c i b l e s u l p h i d e d r o p l e t s . The d r o p l e t s would then s e t t l e back down through the gabbro d u r i n g c r y s t a l l i z a t i o n , g i v i n g r i s e t o the o b s e r v e d v e r t i c a l v a r i a t i o n from d i s s e m i n a t e d t o n e t - t e x t u r e d t o massive o r e a t t h e base o f t h e gabbro. In summary, t h e o l i v i n e gabbro appears t o r e p r e s e n t remnants o f a c r y s t a l l i z e d l o w e r b o r d e r l i q u i d , which c o u l d have formed by f l o w d i f f e r e n t i a t i o n o f t h e p e r i d o t i t e s i l l . The gabbros a t W e l l g r e e n and a t White R i v e r appear t o r e p r e s e n t a l a t e r i n t r u s i v e e v e n t and a r e p o s s i b l y r e l a t e d t o the Maple Creek gabbros. The w r i t e r emphasizes t h a t , a l t h o u g h t h i s h y p o t h e s i s seems to f i t t h e d a t a , i t cannot be c o n s i d e r e d c o n c l u s i v e . 80 G e n e r a t i o n o f t h e K o m a t i i t i c Magmas The Q u i l l Creek complex, r e p r e s e n t a t i v e o f t h e Lower Group complexes, i s composed o f about 20 p e r c e n t d u n i t e , 79 p e r c e n t p e r i d o t i t e (5 p e r c e n t h a r z b u r g i t e , 44 p e r c e n t I h e r z o l i t e , and 30 p e r c e n t w e h r l i t e ) , and about 1 p e r c e n t o l i v i n e gabbro. The c a l c u l a t e d bulk c o m p o s i t i o n i s shown i n T a b l e 5. The s i m i l a r i t y o f the Q u i l l Creek b u l k c o m p o s i t i o n t o the p y r o l i t e c o m p o s i t i o n s o f Green and Ringwood (1967) and Ringwood (1976) i s s t r i k i n g . I t seems r e a s o n a b l e t o c o n s i d e r whether the Q u i l l Creek body c o u l d have formed from a mantle d i a p i r o f p y r o l i t i c c o m p o s i t i o n . P a r t i a l m e l t i n g i n the range 35 t o 50 p e r c e n t would r e s u l t i n a s u s p e n s i o n o f o l i v i n e i n a p y r o x e n i t i c t o p e r i d o t i t i c l i q u i d ( A r n d t , 1977). F o r t y p e r c e n t m e l t i n g c o u l d produce a l i q u i d s i m i l a r i n c o m p o s i t i o n t o t h a t o f the o l i v i n e gabbro " b o r d e r phase" ( T a b l e 6 ) , l e a v i n g an unmelted r e s i d u e o f d u n i t e c o m p o s i t i o n . I n c o m p a t i b l e elements i n th e o l i v i n e gabbro a r e , g e n e r a l l y , more abundant than i n the d u n i t e and p e r i d o t i t e , thus l e n d i n g c r e d e n c e t o such a r e l a t i o n s h i p . The Upper Group complexes c o n s i s t o f about 34 p e r c e n t I h e r z o l i t e , 33 p e r c e n t w e h r l i t e , and 33 p e r c e n t gabbro. The b u l k c o m p o s i t i o n f o r Burwash Creek and Tatamagouche Creek complexes i s s i m i l a r t o t h a t o f th e l i q u i d phase produced by 40 p e r c e n t p a r t i a l m e l t i n g o f t h e Q u i l l Creek bulk c o m p o s i t i o n ( T a b l e 7 ) . T h i s s u g g e s t s t h a t t he complexes o f t h e Upper Group c o u l d have formed from t he l i q u i d f r a c t i o n o f a p y r o l i t e mantle d i a p i r u n d e r g o i n g about 40 p e r c e n t p a r t i a l m e l t i n g . As shown e a r l i e r , k o m a t i i t e s and many o f t h e cumulate r o c k s o f o p h i o l i t e sequences (Coleman, 1977) are c h e m i c a l l y s i m i l a r . In f a c t , t h e o n l y a p p a r e n t chemical (major element) d i s t i n c t i o n i s the lower T i 0 2 c o n t e n t o f the cumulate r o c k s . 81 TABLE 5. D e t e r m i n a t i o n o f bulk c o m p o s i t i o n f o r Q u i l l Creek complex and comparison w i t h p y r o l i t e c o m p o s i t i o n s . 0 X 1 D E 20% , 5% , 44% 30% 1% _BULK N ! Y R 0 L I T E h DUNITE HARZ. LHERZ. WEHR. OL.GAB. COMP? V 2° S i 0 2 41 .3 40.4 42 .8 41 .6 43 .2 42.0 45.16 45.1 T i 0 2 .16 .31 .43 .26 .71 .32 .71 .2 A 1 2 0 3 1 .5 3.0 4 .9 2 .6 7 .0 3.5 3.54 4.6 9 .4 12.0 12 .9 12 .9 14 .0 12.2 9.39 8.7 MnO .16 .14 .14 .13 .15 .14 .14 .1 MgO 45 .0 40.9 35 .1 40 .2 28 .0 38.8 37.47 38.1 CaO .52 1.5 2 .4 2 .0 5 .2 1.9 3.08 3.1 Na 20 .66 .58 .65 .64 .74 .65 .57 .4 K 20 .29 .26 .31 .20 .37 .27 .06 .02 TOTAL 99 .28 99.39 99 .97 100 .83 99 .76 100.1 100.25 100.34 a From Green and Ringwood (1967) b From Ringwood (1976) c As Fe^jOg 82 TABLE 6. C o m p o s i t i o n o f l i q u i d d e r i v e d by v a r i o u s degrees o f p a r t i a l m e l t i n g o f bulk c o m p o s i t i o n f o r Q u i l l Creek complex. OXIDE BULK COMPOSITION LIQUID DERIVED BY PARTIAL MELTING OLIVINE 30% 40% 50% GABRO S i 0 2 T i 0 2 A 1 2 0 3 Fe a r T MnO MgO CaO Na 20 K 20 P 2 ° 5 42.0 .32 3.5 12.2 .14 38.8 1.9 .65 .32 .27 43.6 .69 8.2 18.7 .09 24.3 5.1 .63 .39 .22 43.1 .56 6.5 16.4 .11 29.5 4.0 .64 .37 .24 42.7 .48 5.5 15.0 .12 32.6 3.3 .64 .35 .25 43.2 .71 7.0 14.0 . 15 28.0 5.2 .74 .39 .37 TOTAL 100.1 101.92 101.42 100.94 99.76 a As F e 2 0 3 Note: Dunite c o m p o s i t i o n i s used t o r e p r e s e n t t he approximate " r e s i d u a l " c o m p o s i t i o n . 83 TABLE 7. D e t e r m i n a t i o n o f bulk c o m p o s i t i o n o f Upper Group gabbro-u l t r a m a f i c complexes. OXIDE 34% LHERZOLITE . 33% WEHRLITE , 33% . GABBRO' =BULK COMP-LIQUID. 40% MELT LOWER GP. OL. GABBRO S i 0 2 42.8 42.9 44.8 43.4 43.1. 43.2 T i 0 2 .43 .47 .4 .43 .56 .71 A 1 2 0 3 4.9 4.0 13.6 7.5 6.5 7.0 F e T b 12.9 14.4 12.2 3.2 16.4 14.0 MnO .14 .18 .13 .15 .11 .15 MgO 35.1 34.5 14.7 28.2 29.5 28.0 CaO 2.4 3.4 11.5 5.7 4.0 5.2 Na 20 .65 .72 1.6 .99 .64 .74 K 20 .34 .43 .5 .42 .37 .39 P 2 ° 5 .31 .28 .12 .24 .24 .37 TOTAL 99.97 101.28 99.55 100.23 101.42 99.76 a From T a b l e 6. b As F e o 0 o 84 Most k o m a t i i t e s a r e found i n Precambrian t e r r a n e s ; most o p h i o l i t e s a r e P a l e o z o i c o r younger. K o m a t i i t e s a r e flows o r l e s s commonly i n t r u s i v e s h e e t s and s i l l s and a r e a s s o c i a t e d w i t h younger o r o l d e r b a s a l t i c f l o w s . Cumulate p a r t s o f o p h i o l i t e s are l a y e r e d i n t r u s i v e r o c k s and are a s s o c i a t e d w i t h metamorphic p e r i d o t i t e , s h e e t e d dykes, p i l l o w b a s a l t s , and c h e r t s . I f k o m a t i i t e s a r e formed by p a r t i a l m e l t i n g , perhaps o f p y r o l i t e , then t h e d i f f e r e n c e s between Precambrian k o m a t i i t e s and P a l e o z o i c o p h i o l i t e s i n age, e n v i r o n m e n t , and a s s o c i a t e d r o c k s a r e p o s s i b l y the r e s u l t o f s e c u l a r d e c l i n e i n upper mantle temperatures and c h a n g i n g p a t t e r n s o f c o n v e c t i o n . The o c c u r r e n c e o f Lower T r i a s s i c Kluane k o m a t i i t e s s u g g e s t s t h a t under c e r t a i n t e c t o n i c c o n d i t i o n s the e f f e c t s o f t h e s e s e c u l a r changes may be l o c a l l y overcome. MAPLE CREEK GABBROS The Maple Creek gabbros, p r e v i o u s l y unnamed, a r e s c a t t e r e d t h r o u g h -out Permian v o l c a n i c and s e d i m e n t a r y r o c k s and T r i a s s i c b a s a l t f l o w s . These dykes and s i l l s a r e g e n e r a l l y l e s s than 50 m wide, a l t h o u g h a dyke i n t h e N i k o l a i Greenstone n e a r Tatamagouche Creek measures 580 m by 120 m. The g r e e n i s h - b r o w n , medium-grained, d i a b a s i c gabbro c o n s i s t s o f about 40 p e r c e n t a u g i t e , 50 p e r c e n t p l a g i o c l a s e , and 10 p e r c e n t o l i v i n e , o r t h o p y r o x e n e , h o r n b l e n d e , and m a g n e t i t e . A l t e r a t i o n p r o d u c t s i n c l u d e s e r p e n t i n e , u r a l i t e , c h l o r i t e , c a l c i t e , s a u s s u r i t e , and e p i d o t e . Whole rock a n a l y s e s ( T a b l e 8) show S n ^ s l i g h t l y under 50 p e r c e n t , T i 0 o about 1 p e r c e n t , and F e 0 T s l i g h t l y g r e a t e r than MgO. The norms 85 TABLE 8. Whole rock c h e m i s t r y , CIPW norms, and t r a c e element data f o r Maple Creek gabbros. OXIDE SAMPLES FROM THIS STUDY G.S.C. SAMPLES 138-1 1095-1 1149-2A 50-2 59-1 118-1 5369 5387 5388 5390 5392 S i 0 2 47.5 48.2 51.1 52. .8 50.2 48.2 T i 0 2 .91 .50 .54 , .93 .54 .97 .64 .87 1. .6 1.14 .69 A 1 2 0 3 13.1 13.1 13.0 14.3 9.3 12.9 13.1 14.6 13.5 14.7 14.8 *S 12.7 12.3 12.3 11.9 13.2 12.8 l . l a 6.1 b 0.9 a 7.7 b 0. 9. ,2 a , l b 0.9 a 8.6 b 0.5 a 6.5 b MnO .17 .15 .16 .23 .17 .13 MgO 7.9 8.7 7.7 9.4 18.5 7.9 10.3 7.5 5, .27 8.45 10.1 CaO 10.6 10.3 9.5 10.0 8.8 10.2 14.5 10.2 5. .95 11.9 11.5 Na 20 2.6 1.9 3.1 4. ,6 2.0 3.2 K 20 .69 .59 1.37 1. ,5 .59 .77 P2°5 .33 .05 .13 .31 .13 .09 L.O.I. 1.7 4.0 2.9 3. ,3 1.4 3.8 S .0 .0 .0 .0 .0 .0 TOTAL 97.76 100.7 100.5 100. 4 100.5 100.3 O r t h o c l a s e 4.29 1.34 8.35 9. 46 3.34 4.45 A l b i t e 22.81 15.22 26.23 39. 86 16.78 18.87 A n o r t h i te 22.25 23.91 22.26 12. 25 30.05 25.05 Di o p s i d e 23.8 40.90 25.74 15. .41 24.48 27.81 Hype rsthene 10.04 10. 35 18.89 Magnetite 2.34 1.62 1.39 i •j. ,24 1.39 . 0.69 A p a t i t e .82 I l m e n i t e 1.95 1.21 1.67 3. 03 2.27 1.36 01i v i ne 11.7 12.21 13.61 6. 33 3.39 17.19 Nepheli ne 0.86 .80 4.82 Mg/(Mg+Fe)in S i l i c a t e s 61.3 Cu • 116 118 121 112 119 80 N.D. Ni 75 92 103 174 520 92 100 110 80 170 150 Co 46 62 47 88 62 51 N.D. Cr 390 350 280 .600 1200 440 N.D. Zn 88 74 71 79 91 124 20 40 70 60 30 Ba 179 775 242 279 28 168 N.D. Sr 181 303 246 209 34 225 190 260 250 200 250 Rb 9 33 22 33 1 13 - 10 - - -Nb 5 4 4 6 6 7 N.D. Zr 61 32 39 63 45 56 - - 60 - -Y 19 18 19 21 14 21 N.D. a As Fe 20 b As FeO 86 show t h a t t h e Maple Creek gabbros a r e o l i v i n e t h o l e i i t e s g e n e r a l l y , but a l t h o u g h T i C ^ i s s l i g h t l y h i g h , most can a l s o be c l a s s i f i e d as b a s a l t i c k o m a t i i t e s (see F i g u r e 4 ) . The t r a c e element s i g n a t u r e o f a l l Maple Creek gabbros i s s i m i l a r . Cu, N i , Co and Cr v a l u e s a r e g e n e r a l l y l o wer, and Ba, S r and Y c o n t e n t s a r e h i g h e r than those f o r gabbros i n the Kluane complexes. F i e l d , : p e t r o g r a p h i c , and chemical d a t a and t h e s t r a t i g r a p h i c r e -s t r i c t i o n o f Maple Creek gabbro s i l l s and dykes t o Lower Permian r o c k s and Upper T r i a s s i c b a s a l t s s u g g e s t a p o s s i b l e g e n e t i c r e l a t i o n s h i p . The c h e m i s t r y o f t h e gabbros i s s i m i l a r to t h a t o f t h e b a s a l t s - t h e i r c h e m i c a l ranges o v e r l a p - t h e gabbros c o n t a i n s l i g h t l y h i g h e r MgO, and lower A^O^, FeOj, and a l k a l i e s . Ranges i n t r a c e elements a l s o o v e r l a p - gabbros d i s p l a y h i g h e r N i , Co and C r , and a narrower range f o r each o f S r , Rb, Nb, Z r , and Y than N i k o l a i G r e e n s t o n e . Perhaps t h e N i k o l a i Greenstone i s t h e e x t r u s i v e e q u i v a l e n t o f the Maple Creek gabbros and t h e s l i g h t c h emical d i f f e r e n c e s a r e t h e r e s u l t o f m i l d d i f f e r e n t i a t i o n . CONCLUSIONS S i l l s o f t h e Kluane complexes may be d i v i d e d i n t o a Lower Group -l a r g e l y p e r i d o t i t i c b o d i e s w i t h i n Lower Permian g r a d a t i o n a l c o n t a c t zone r o c k s , and an Upper Group - g a b b r o - p e r i d o t i t e i n t r u s i o n s w i t h i n Lower Permian Hasen Creek F o r m a t i o n . Lower Group complexes c o n s i s t o f p e r i d o t i t e u n d e r l a i n by d u n i t e and have a b o r d e r zone o f o l i v i n e gabbro. T h i s group i s h o s t t o s u b s t a n t i a l n i c k e l - c o p p e r s u l p h i d e d e p o s i t s . Upper Group complexes a r e composed o f p e r i d o t i t e o v e r l a i n by gabbro. Cross s e c t i o n s 87 i l l u s t r a t i n g m i n e r a l modes s u g g e s t d i f f e r e n t i a t i o n by f l o w (and g r a v i t y a c c u m u l a t i o n ) f o r t h e Lower Group and by g r a v i t y a c c u m u l a t i o n f o r t he Upper Group. C h e m i c a l l y , both the Lower and Upper Group g a b b r o - u l t r a m a f i c complexes a r e p y r o x e n i t i c and p e r i d o t i t i c k o m a t i i t e s . The i n t e r n a l s t r u c t u r e s o f Kluane complexes a r e comparable t o those o f t h e k o m a t i i t i c flows and s i l l s . Maple Creek gabbros a r e p e t r o g r a p h i c a l l y and c h e m i c a l l y s i m i l a r t o Upper T r i a s s i c N i k o l a i Greenstone and are c o n s i d e r e d t o be i n t r u s i v e phases o r f e e d e r s f o r t h e b a s a l t f l o w s . C h e m i c a l l y , t he gabbros and b a s a l t s a r e i n t e r m e d i a t e between b a s a l t i c k o m a t i i t e s and t h o l e i i t e s . The o c c u r r e n c e o f Upper T r i a s s i c k o m a t i i t i c s i l l s i n the Canadian C o r d i l l e r a has i m p o r t a n t i m p l i c a t i o n s . Kluane complexes show t h a t p y r o x e n i t i c and p e r i d o t i t i c k o m a t i i t e s a r e not unique t o the Precambrian S h i e l d . Some o f t h e Kluane k o m a t i i t e s a r e h o s t s t o n i c k e l - c o p p e r d e p o s i t s . Thus, f o r e x p l o r a t i o n i n the C o r d i l l e r a , e v a l u a t i o n o f the type o f u l t r a m a f i c body, t h a t i s , whether a l p i n e , zoned, o r k o m a t i i t i c , c o u l d prove i m p o r t a n t t o d e t e r m i n i n g the p o t e n t i a l f o r a s s o c i a t e d s u l p h i d e o r e s . ACKNOWLEDGEMENTS F i n a n c i a l s u p p o r t f o r t h i s s t u d y was o b t a i n e d from the N a t i o n a l Research C o u n c i l o f Canada thro u g h an N.R.C. P o s t g r a d u a t e S c h o l a r s h i p t o S.W. Campbell and o p e r a t i n g g r a n t s to Dr. A . J . S i n c l a i r . L a t e r c o n t r i b u t i o n s , t o a i d i n c o m p l e t i o n o f s p e c i f i c a s p e c t s o f the s t u d y came from the A r c t i c and A l p i n e I n s t i t u t e o f the U n i v e r s i t y o f B r i t i s h Columbia, Western Mines L t d . , Vancouver, and Or e q u e s t , Vancouver. F i e l d s u p p o r t , 88 i n c l u d i n g h e l i c o p t e r t i m e , was p r o v i d e d by the G e o l o g i c a l Survey o f Canada, Department o f I n d i a n and N o r t h e r n A f f a i r s , and Western Mines L t d . The w r i t e r extends s p e c i a l thanks t o Dr. K.C. McTaggart f o r h i s guidance and h e l p i n p r e p a r i n g the m a n u s c r i p t . Numerous i n d i v i d u a l s have c o n t r i b u t e d t o t h i s s t u d y , i n c l u d i n g Drs. R.B. Campbell, J.W.H. Monger, P.B. Read, D.B. C r a i g , C.I. Godwin and A.E. S o r e g a r o l i , and C.A. A i r d , D. Tenny, J.S. V i n c e n t , J . Burakso, A . L . J . MacDonald, W.B Green, P. V e r s l u c e , B. C r a n s t o n , K. S c o t t , and S. Horsky. M. M u e h l e r t and H. P i l t z a s s i s t e d i n the f i e l d work. 89 REFERENCES A r n d t , N.T. 1977. T h i c k , l a y e r e d p e r i d o t i t e - g a b b r o l a v a flows i n Munro Township, O n t a r i o . Canadian J o u r n a l o f E a r t h S c i e n c e s , 14 , pp. 2620-2637. A r n d t , N.T., N a l d r e t t , A . J . , and Pyke, D.R. 1977. K o m a t i i t i c and i r o n -r i c h t h o l e i i t i c l a v a s o f Munro Township, N o r t h e a s t O n t a r i o . J o u r n a l o f P e t r o l o g y , 18 , pp. 319-369. B h a t t a c h a r j i , S. 1967. Mechanics o f flow d i f f e r e n t i a t i o n i n u l t r a m a f i c and m a f i c s i l l s . J o u r n a l o f Geology, 75 , pp. 101-112. Br o o k s , C , and H a r t , S.R. 1974. On the s i g n i f i c a n c e o f k o m a t i i t e . Geology, 2 , pp. 107-110. Campbell, R.B., and Dodds, C.J. 1978. O p e r a t i o n S a i n t E l i a s , Yukon T e r r i t o r y . In_ C u r r e n t Research. G e o l o g i c a l Survey o f Canada, Paper 78-1A, pp. 35 -41 . Coleman, R.G. 1977. O p h i o l i t e s : a n c i e n t o c e a n i c l i t h o s p h e r e ? S p r i n g e r -V e r l a g , New York, 229 p. G a l e , G.H. 1973. P a l e o z o i c b a s a l t i c k o m a t i i t e and o c e a n - f l o o r type b a s a l t s from n o r t h e a s t e r n Newfoundland. E a r t h and P l a n e t a r y S c i e n c e L e t t e r s , 18 , pp. 22-28. Gibb, F.G.P. 1968. Flow d i f f e r e n t i a t i o n i n the x e n o l i t h i c u l t r a b a s i c dykes o f t h e Cui11 i n s and t h e S t r a t h a i r d P e n i n s u l a , I s l e o f Skye, S c o t l a n d . J o u r n a l o f P e t r o l o g y , 9 , pp. 411 - 4 4 3 . Green, D.H., and Ringwood, A.E. 1967. The g e n e s i s o f b a s a l t i c magma. C o n t r i b u t i o n s t o M i n e r a l o g y and P e t r o l o g y , 1 5 , pp. 103-109. I r v i n e , T.N. 1974. U l t r a m a f i c and g a b b r o i c r o c k s i n the Aike n Lake and McConnell Creek map-areas, B r i t i s h Columbia. G e o l o g i c a l Survey o f Canada, Paper 74-1A, pp. 149-152. McKechnie, N.D. 1965. Resume o f p u b l i s h e d e v i d e n c e o f u l t r a m a f i c r o c k s i n B r i t i s h Columbia. Western Miner, A p r i l , pp. 64-76. McTaggart, K.C. 1971. On t h e o r i g i n o f u l t r a m a f i c r o c k s . G e o l o g i c a l S o c i e t y o f America B u l l e t i n , 8 2 , pp. 23-42 . M u l l e r , J . E . 1967. Kluane Lake map-area, Yukon T e r r i t o r y . G e o l o g i c a l Survey o f Canada, Memoir 340, 137 p. N a l d r e t t , A . J . 1972. Archean u l t r a m a f i c r o c k s . I_n t h e A n c i e n t O c e a n i c L i t h o s p h e r e . E a r t h P h y s i c s Branch P u b l i c a t i o n Department o f Energy, Mines, and Reso u r c e s , Ottawa, pp. 141-151. N a l d r e t t , A . J . 1973. N i c k e l s u l p h i d e d e p o s i t s - t h e i r c l a s s i f i c a t i o n and g e n e s i s , w i t h s p e c i a l emphasis on d e p o s i t s o f v o l c a n i c a s s o c i a t i o n . Canadian I n s t i t u t e o f Mi n i n g and M e t a l l u r g y T r a n s a c t i o n s , 76, pp. 183-201. 90 N a l d r e t t , A . J . , and C a b r i , L . J . 1976. U l t r a m a f i c and m a f i c r o c k s : t h e i r c l a s s i f i c a t i o n and g e n e s i s w i t h s p e c i a l r e f e r e n c e t o the c o n c e n t r a t i o n o f n i c k e l s u l p h i d e s and p l a t i n u m - g r o u p e l e m e n t s . Economic Geology, 71, pp. 1131-1158. N a l d r e t t , A . J . , and Goodwin, A.M. 1977. V o l c a n i c r o c k s o f the B l a k e R i v e r Group, A b i t i b i Greenstone B e l t , O n t a r i o , and t h e i r s u l p h u r c o n t e n t . Canadian J o u r n a l o f E a r t h S c i e n c e s , 14, pp. 539-550. N a l d r e t t , A . J . , and T u r n e r , A.R. 1977. The geology and p e t r o g e n e s i s o f a g r e e n s t o n e b e l t and r e l a t e d n i c k e l s u l p h i d e m i n e r a l i z a t i o n a t Y a k a b i n d i e , Western A u s t r a l i a . Precambrian Research, 5, pp. 43-103. Pyke, D.R., N a l d r e t t , A . J . , and E c k s t r a n d , O.R., 1973. Archean u l t r a m a f i c flows i n Munro Township, O n t a r i o . G e o l o g i c a l s o c i e t y o f America B u l l e t i n , 84, pp. 955-978. Read, P.B., and Monger, J.W.H. 1976. P r e - C e n o z o i c v o l c a n i c assemblages o f the Kluane and A l s e k Ranges, southwestern Yukon T e r r i t o r y . G e o l o g i c a l Survey o f Canada, Open F i l e Report 381, 96 p. Ringwood, A.E. 1975. C o m p o s i t i o n and p e t r o l o g y o f t h e E a r t h ' s mantle. M c G r a w - H i l l , New York, pp. 11-322. S i m k i n , T. 1967. Flow d i f f e r e n t i a t i o n i n the p i c r i t i c s i l l s o f North Skye. Xn U l t r a m a f i c and r e l a t e d r o c k s . E d i t e d by P.J. W y l l i e . W i l e y and Sons, New York, pp. 64-68. V i l j o e n , M.J., and V i l j o e n , R.P. 1969. The geology and g e o c h e m i s t r y o f the l o w e r u l t r a m a f i c u n i t o f the Onverwacht Group and a proposed new c l a s s o f igneous r o c k . J_n Upper Mantle P r o j e c t . G e o l o g i c a l S o c i e t y o f South A f r i c a , S p e c i a l P u b l i c a t i o n No. 2, pp. 55-86. 91 CHAPTER 4 GENETIC IMPLICATIONS OF SULFUR ISOTOPE DATA  FOR MINERAL DEPOSITS IN THE KLUANE RANGES, SOUTHWESTERN YUKON TERRITORY 92 ABSTRACT In a r e g i o n a l s t u d y o f cop p e r d e p o s i t s i n the Kluane Ranges, southwestern Yukon T e r r i t o r y , e i g h t y s u l f u r i s o t o p i c a n a l y s e s , combined w i t h d e t a i l e d g e o l o g i c a l i n f o r m a t i o n , p r o v i d e e v i d e n c e c o n c e r n i n g g e n e s i s o f t h r e e d i s t i n c t c a t e g o r i e s o f d e p o s i t s . In n i c k e l - c o p p e r s u l f i d e d e p o s i t s a s s o c i a t e d w i t h Kluane gabbro-u l t r a m a f i c complexes, 30 t o 60 p e r c e n t o f the s u l f u r was p r o b a b l y d e r i v e d by c o n t a m i n a t i o n o f p r i m a r y mantle s u l f u r w i t h s u l f u r from p y r i t i c w a l l r o c k s . A l t h o u g h d i s s o c i a t i o n o f w a l l r o c k p y r i t e and f l u i d t r a n s p o r t seems the most l i k e l y mechanism, a s s i m i l a t i o n o f the p y r i t i c w a l l r o c k s i s a l s o a p o s s i b l e t r a n s f e r mechanism o f s u l f u r from w a l l r o c k t o magma. T h i s c o n t a m i n a t i o n may have p r o v i d e d the n e c e s s a r y a d d i t i o n a l s u l f u r t h a t caused e a r l y s a t u r a t i o n and e n a b l e d s e g r e g a t i o n o f i m m i s c i b l e s u l f i d e m e l t s l e a d i n g t o f o r m a t i o n o f n i c k e l - c o p p e r s u l f i d e c o n c e n t r a t i o n s . G a b b r o i c t o u l t r a m a f i c magmas emplaced i n s u l f u r - b e a r i n g ( e s p e c i a l l y p y r i t i c ) c o u n t r y r o c k s may have more economic p o t e n t i a l than t h o s e emplaced i n s u l f u r - p o o r r o c k s . Small s u l f i d e - b e a r i n g v e i n l e t s i n Permian t u f f a c e o u s and f l o w r o c k s ( S t a t i o n Creek Formation) appear t o have d e v e l o p e d by l o c a l m o b i l i z a t i o n o f p r e - e x i s t i n g s u l p h i d e s i n t o s m a l l d i l a t e n t zones d u r i n g r e g i o n a l metamorphism. No w h o l e s a l e homogenization o f s u l f u r o c c u r r e d . In c o n t r a s t , v e i n s u l f i d e s i n T r i a s s i c N i k o l a i Greenstone b a s a l t s appear t o have formed i n open systems. T h e i r s u l f u r i s o t o p i c c o m p o s i t i o n s r e q u i r e w i d e l y v a r y i n g f ^ c o n d i t i o n s as w e l l as v a r i a b l e s u l f u r s o u r c e s ( p r o b a b l y connate seawater i n both Permian Hasen Creek Formation and the lower p a r t o f T r i a s s i c N i k o l a i Greenstone) w i t h 93 s i g n i f i c a n t l y d i f f e r e n t i s o t o p i c c o m p o s i t i o n s . INTRODUCTION AND GEOLOGIC SETTING M i n e r a l o c c u r r e n c e s i n the Kluane Ranges o f southwestern Yukon T e r r i t o r y ( F i g u r e 1) have g e n e r a t e d i n t e r e s t s i n c e the b e g i n n i n g o f the t w e n t i e t h c e n t u r y ( C a i r n e s , 1915). N a t i v e copper o c c u r r e n c e s a l o n g K l e t s a n Creek and White R i v e r were known to n a t i v e I n d i a n s b e f o r e 1900. At t h e t u r n o f t h e c e n t u r y p l a c e r miners were a t t r a c t e d t o the Kluane a r e a and i n 1904 g o l d p l a c e r s were s t a k e d on Burwash and Arch C r e e k s . Then and now, Burwash Creek i s t h e l a r g e s t p r o d u c e r o f g o l d i n the Kluane Ranges. Copper o c c u r r e n c e s on White R i v e r were s t a k e d i n 1905 and those i n the Q u i l l Creek a r e a i n 1914. Renewed a c t i v i t y , which f o l l o w e d c o m p l e t i o n of the A l a s k a Highway i n the mid 1940's, s h i f t e d i n t e r e s t t o l o d e d e p o s i t s , and the d i s c o v e r y i n 1952 o f massive n i c k e l - c o p p e r s u l p h i d e s i n t h e Q u i l l Creek area t r i g g e r e d a new phase o f e x p l o r a t i o n a l o n g t he e n t i r e l e n g t h o f the Kluane Ranges. In 1954 s i m i l a r d e p o s i t s were d i s c o v e r e d near t h e White Ri v e r . P r o d u c t i o n has been m a i n l y from p l a c e r g o l d d e p o s i t s . P r o d u c t i o n from l o d e d e p o s i t s ( F i g u r e 1) has been l i m i t e d t o W e l l g r e e n Mine ( Q u i l l Creek a r e a ) , which produced n i c k e l , c o p p e r , p l a t i n u m , and c o b a l t i n 1972 and 1973 and Johobo Mine, a p r o d u c e r o f copper and s i l v e r from 1958 t o 1962 (Green and Godwin, 1963). The Kluane Ranges a r e p a r t o f a f a u l t - s e g m e n t e d b l o c k , t he Taku-S k o l a i T e r r a n e , f o r m i n g t he e a s t e r n p a r t o f W r a n g e l l i a (Monger and P r i c e , 1979), which l i e s w i t h i n t he S a i n t E l i a s f o l d b e l t i n so u t h w e s t e r n Yukon 94 F i g u r e 1. L o c a t i o n map o f base metal d e p o s i t s i n the f o o t h i l l s o f S a i n t E l i a s M o u n t a i n s , Yukon T e r r i t o r y . D e p o s i t s f o r m i n g p a r t o f t h i s s t u d y a r e : l=Cu-Fe a t P i c k h a n d l e p r o p e r t y ; 2=Ni-Cu a t Canalask p r o p e r t y ; 3=Ni-Cu a t Arch Creek p r o p e r t y ; 4=Ni-Cu a t Well green Mine; 5=Cu a t S i l v e r C i t y p r o p e r t y ; 6=Cu a t Q u i l l Creek Mines p r o p e r t y ; 7=Cu a t A l i c e Lake Mines p r o p e r t y ; 8=Cu a t Johobo Mine. 95 T e r r i t o r y . T h i s f o l d b e l t i s c h a r a c t e r i z e d by an abundance o f major s u b p a r a l l e l f a u l t s w i t h d e x t r a l s t r i k e - s l i p movement ( E i s b a c h e r , 1976; Campbell and Dodds, 1978; 1979). The T a k u - S k o l a i T e r r a n e i s wedged between the Duke R i v e r F a u l t and a d j a c e n t P a l e o z o i c r o c k s o f the A l e x a n d e r T e r r a n e t o the southwest and the Shakwak-Dalton F a u l t and a d j a c e n t metamorphic and i n t r u s i v e r o c k s o f the Yukon C r y s t a l l i n e Complex to the n o r t h e a s t . The T a k u - S k o l a i T e r r a n e i s u n d e r l a i n by Permo-Pennsylvanian t o Lower C r e t a c e o u s v o l c a n i c and s e d i m e n t a r y r o c k s t h a t a r e c u t by b o d i e s o f C r e t a c e o u s g r a n o d i o r i t e and T e r t i a r y q u a r t z l a t i t e p o r p h y r y . B r i e f d e s c r i p t i o n s o f the p r i n c i p a l u n i t s and a s s o c i a t e d m i n e r a l o c c u r r e n c e s ( C a m p b e l l , 1976; and C h a p t e r 2) a r e p r e s e n t e d i n T a b l e 1 and an i d e a l i z e d c r o s s s e c t i o n showing t h e i r r e l a t i o n s h i p i s i l l u s t r a t e d i n F i g u r e 2. The base metal o c c u r r e n c e s have been grouped i n t o f i v e m e t a l l o g e n i c c a t e g o r i e s by Read and Monger (1976) as summarized i n T a b l e 2. Of t h e s e , the p r e s e n t s t u d y i s c o n c e r n e d w i t h c a t e g o r i e s 1, 2, and 3; n i c k e l -c o p p e r - p l a t i n u m r e l a t e d t o u l t r a m a f i c b o d i e s , copper i n N i k o l a i Greenstone, and copper i n S k o l a i Group r o c k s . A l l p r o p e r t i e s l i s t e d i n T a b l e 2, which r e p r e s e n t o c c u r r e n c e s i n t h e s e c a t e g o r i e s , as w e l l as p y r i t i c s u l p h i d e s i n the Lower Permian T r a n s i t i o n Zone, were examined a t l e n g t h i n the f i e l d and sampled f o r a n a l y s i s o f s u l f u r i s o t o p i c c o m p o s i t i o n s . Kluane n i c k e l - c o p p e r d e p o s i t s have been i n t e r p r e t e d as i n j e c t i o n s u l f i d e d e p o s i t s o f magmatic o r i g i n ( E c k s t r a n d , 1972). Much o f the n a t i v e copper i n N i k o l a i Greenstone may be a p r o d u c t o f supergene e n r i c h -ment d u r i n g w e a t h e r i n g (Kirkham, 1972), whereas a s s o c i a t e d copper s u l f i d e s a r e i n t e r p r e t e d as b e i n g much younger and r e l a t e d i n o r i g i n t o low grade r e g i o n a l metamorphism superimposed on the b a s a l t s ( S i n c l a i r e t a l . , 96 TABLE 1. Pre-Tertiary Rock Units and Associated Mineral Occurrences in the Kluane Ranges, Yukon. AGE ROCK TYPE DESCRIPTION MINERAL OCCURRENCES Cretaceous Granitic Plutons McCarthy Formation Nizina and Chitistone Limestones Upper Triassic Nikolai Greenstone Middle to Upper Maple Creek Gabbros Triassic Lower Triassic Kluane Gabbro-Ultramafic Comp1 exes Hasen Creek Formation Alaskite, granite, hornblende-biotlte granodiorite, and diorite. Thinly bedded limestone and argi l l i te. Massive limestone, limestone breccia and minor thinly bedded limestone and gypsum. Basalt flows, affected by prehnite-pumpellyite metamorphism, overlie a thin, discontinuous basal basalt breccia. Minor limestone and shale occur in lower part of basalt pile. Gabbro s i l ls and dikes intrude Station Creek and Hasen Creek Formations and into the Nikolai Greenstone. Gabbro-peridotite s i l ls intrude Hasen Creek Formation. Peridotitic s i l l s , consisting of peridotite, dunite, and minor olivine gabbro, intrude the Transition Zone. Ultramafic rocks are severely serpentinized; gabbroic rocks are partly uralitized. Cherty argi l l i te , shale and siltstone, with interbedded limestone and minor discontinuous sandstone and conglomerate. Chalcocite, bornite, minor chalco-pyrite, and pyrite are intimately associated with metamorphic minerals and occur in amygdules, stringers and veins that generally crosscut flows. Locally, native copper is present Pyrrhotite, pentlandita, and chalco-pyrite occur as disseminations in peridctite and olivine gabbro of the more ultramafic s i l l s . Also present, locally, are massive pods of nickel-copper sulfides at or near the base of these peridotitic s i l l s . Lower Permian (in part, Pennsylvanian) Transition Zone (Upper 400 m of Station Creek Formation) Station Creek Formation occurs as tiny grains, dis-Interbedded black shale, siltstone, fine-grained Pyri tuff, cherty argi l l i te , ana argillaceous limestone, seminated in thin layers in cherty Forms a gradational contact between Station Creek argi l l i te , generally appearing and Hasen Creek Formations. Basaltic andesite flows, overlain by tuff and lapi l l i tuff, and locally capped by agglomerate. Interbedded argillaceous rocks and limestone. Metamorphosed to chlorite schist and phyllite 1 oca 11y. stratabound. Chalcopyrite, as disseminations and along fractures in argillaceous limestone. Chalcopyrite, pyrite and minor pyrrhotite occur in veins and seams mostly subparallel to foliation, as lenses and dis-seminations, and in quartz-calcite-apidote veins. ,l£5 "SI F i g u r e 2. Schematic c r o s s s e c t i o n o f mineral o c c u r r e n c e s and s t r a t i g r a p h y i n the Kluane Ranges. I n t r u s i o n s and m i n e r a l o c c u r r e n c e s are shown i n i d e a l i z e d f a s h i o n , but r o u g h l y i n t h e i r c o r r e c t " s t r a t i g r a p h i c " p o s i t i o n s . 98 TABLE 2. C l a s s i f i c a t i o n o f Lode Metal O c c u r r e n c e s , Kluane Ranges''' CATEGORY PROPERTY REFERENCES (1) Ni-Cu-Pt Well green Mine Canalask P r o p e r t y Campbell (1960) Arch Creek P r o p e r t y Campbell (1976) L i n d a Creek P r o p e r t y S i l v e r C i t y P r o p e r t y S i n c l a i r (1974) S i n c l a i r e t al_. (1979) A l i c e Lake Mines P r o p e r t y Q u i l l Creek Mines P r o p e r t y (3) Cu i n S k o l a i P i c k h a n d l e P r o p e r t y Chapter 2 Group (4) Porphyry Cu Cork Claims C h r i s t o p h e r e t a l . D e p o s i t s (1972) (5) Ag-Pb Vein s (2) Cu i n N i k o l a i Greenstone 1 A f t e r Read and Monger (1976). 99 1979). P r i o r t o t h i s work no d e t a i l e d s t u d y o f t h e o r i g i n o f c o p p e r s u l f i d e s i n S k o l a i r o c k s has been p u b l i s h e d , a p a r t from an u n p u b l i s h e d p r o p e r t y r e p o r t by S.W. Campbell f o r Western Mines L t d . , Vancouver. The purpose o f t h i s s t u d y was t o d e v e l o p and t e s t p r o b a b l e g e n e t i c models f o r the t h r e e f o r g o i n g c a t e g o r i e s o f d e p o s i t s u s i n g s u l f u r i s o t o p i c data to supplement g e o l o g i c a l o b s e r v a t i o n s . ANALYTICAL METHOD AND RESULTS Samples f o r s u l f u r i s o t o p e d e t e r m i n a t i o n were take n from p e r i d o t i t e -h o s t e d n i c k e l - c o p p e r s u l f i d e o c c u r r e n c e s , d i s s e m i n a t e d p y r i t e i n T r a n s -i t i o n Zone r o c k s (see T a b l e 1 ) , and from v a r i o u s copper s u l f i d e o c c u r r e n c e s i n both S t a t i o n Creek Formation and N i k o l a i Greenstone. D i s s e m i n a t e d s u l f i d e s i n p u l v e r i z e d rock were c o n c e n t r a t e d by panning and/or use o f a v i b r a t i n g t a b l e and by heavy l i q u i d s e p a r a t i o n u s i n g diodomethane. S u l p h i d e s i n massive ore specimens were d r i l l e d o u t . S e p a r a t i o n o f i n d i v i d u a l s u l f i d e m i n e r a l s was a c c o m p l i s h e d on a Franz magnetic s e p a r a t o r . A n a l y s e s were done a t McMaster U n i v e r s i t y under the s u p e r v i s i o n o f Dr. C.E. Rees. S u l f u r i s o t o p e r e s u l t s a r e l i s t e d i n T a b l e s 3, 4, and 5. A n a l y t i c a l p r e c i s i o n ( s ) i s e s t i m a t e d t o be 0.2 p e r m i l , based on 25 samples o f which 15 are from d a t a i n c l u d e d i n the t a b l e s , and u s i n g the f o r m u l a where X 1 and X 2 a r e d u p l i c a t e a n a l y s i s , and N i s the number o f d u p l i c a t e s . P a r t i t i o n i n g o f s u l f u r i s o t o p e s i n p y r r h o t i t e - c h a l c o p y r i t e p a i r s from the n i c k e l - c o p p e r d e p o s i t s i s shown i n F i g u r e 3. The f r a c t i o n a t i o n 100 TABLE 3. Su l fur Isotopic Compositions of Sul f ides in Nickel-Copper Deposits. Sample Ore 634s °/oo Percent Su l fur Number Type po CP pn po cp pn Wellgreen Property • - Surface Showinas* 78-1 MS -6.0 -5 .8 28. .0 30.9 1119-6 MS -5.4 -5.8 15. .5 27.8 1120-6,-9 GS -6.1 -6.2 -6.6 16. 16. .5 .5 31.9 1120-7 GS -8.0 21. .2 1120-13,-14 GS -6.0 -5.7 7. .8 31.0 Wellgreen Property • - Underground and Stockp i le 2 El-71-526 PS -5 .8 -3 .5 12. .3 18.3 El-71-533 MS -5.8 -5.7 -5.6 30. .7 33.3 24.7 El-72-121 GS -4.2 -4.1 -4.1 28. 28. .3 .5 30.2 El-72-129 MS -5.8 -5.4 30. .2 23.2 E l -72-132 3 GS -5.5 -4.3 -5.4 -5.5 29. .5 33.2 31.0 30.7 El-72-134 MS -3.2 -2.8 29. .4 30.7 El-72-138 MS -5.9 -5.8 -6.3 -6.3 30. ,2 32.5 31.9 32.0 El-72-139 BS -3 .5 28. .5 El-72-140 MS -3.3 -3.4 -3.5 -4.0 28. .6 32.9 30.8 32.7 El-72-147 GS -3.6 -3.7 -3.9 29. .4 34.1 30.5 El-72-149 GS -3.7 -3.6 32. .6 30.6 El-72-151 GS -4 .0 -3.9 25. 24. .1 .4 E l -72-154 3 GS -3.9 -3.8 -4 .3 26. .0 34.0 30.8 El-72-158 MS -6.5 30. .0 Arch Creek Property - Surface Showings* 1101-4 MS -5.9 -6.6 22. .7 28.8 .1101-6 PS -8.3 -7.0 -7.6 25. .2 33.4 31.7 Canalask Property - Surface Showings''' 281-3 PS -14.4 19. 5 298-1 MS -18.3 10. .7 1168-3,-4 DVS -18.7 -18.1 -18.3 20. 7 24.4 24.7 1168-5 MS -18.6 32. 1 1 Sample c o l l e c t i o n by S.W. Campbell 2 Sample co l l ec t i on by O.R. Eckstrand 3 Sample taken from s tockp i le Abbreviat ions: MS = massive s u l f i d e ; GS = su l f i de in gabbro; PS = su l f i de in p e r i d o t i t e ; BS = su l f i de in breccia ore; DVS = disseminated ve in-interconnected s u l f i d e ; po = py r rho t i te ; cp = cha lcopyr i te ; pn = pent landi te . 101 TABLE 4. S u l f u r I s o t o p i c Compositions o f S u l f i d e s i n S t a t i o n Creek V o l c a n i c Rocks and i n Rocks o f the T r a n s i t i o n Zone. — _ Sample Type o f Number O c c u r r e n c e S 3 4S °/oo P e r c e n t S u l f u r py po cp py PO cp P i c k h a n d l e P r o p e r t y * P1007 DS -0.4 33.7 P1009 DS +8.8 38.9 VS +6.9 33.6 P1024 VS +1.1 44.2 P1050 VS +0.9 -0.1 2.7 32.3 Well green Area - T r a n s i t i o n Zone* 1065 DS -24.3 46.0 1133 DS -13.3 39.9 Canalask A r e a - T r a n s i t i o n Zone* 279-1 DS -35.9 43.3 1164 DBS -22.2 35.0 1 Sample c o l l e c t i o n by S.W. Campbell A b b r e v i a t i o n s : DS = d i s s e m i n a t e d s u l f i d e ; VS = v e i n s u l f i d e ; DBS = d i s s e m i n a t e d banded s u l f i d e s ; py = p y r i t e ; po = p y r r h o t i t e ; cp = c h a l c o p y r i t e . 102 TABLE 5. S u l f u r I s o t o p i c Compositions o f S u l f i d e s i n N i k o l a i Greenstone Sample Type o f £ 3 4 S o/oo Percent S u l f u r Number Occurrence py cp cc bo py cp cc CO S i l v e r C i t y P r o p e r t y * 40/4/1 +10.9 +10. .7 13.0 18. .7 40/2/4A - 6.0 -5. .2 30.1 20. .4 40/2/4B + 0.6 -1. -1. .0 .2 31.3 23. 23. .8 ,5 SHED +6.5 +6.5 14 14. .2 .1 40/102-1/221 +22. +22. .0 .0 36 36 .8 .2 y S i l v e r C i t y P r o p e r t y KQ-70-225(l) VS +8.7 +8.4 14 14 .4 .4 KQ-70-225(2) VS +16.8 13 .6 KQ-70-226A VS -17.9 18. .2 KQ-70-226B VS -17.3 14. .2 KQ-70-231A + 7.6 16. .7 A l i c e Lake Mines Showinq^ KQ-70-242 -23. 1 5. 0 KQ-70-243(l) - 6. 0 17. 3 KQ-70-243(2) - 8. 1 19. 8 2 Q u i l l Creek Mines Showinq KQ-70-244 - 3.7 .05 KQ-70-246 -14. 8 3 5. ,0 3 KQ-70-247 -22.7 2.7 2 Johobo P r o p e r t y KQ-70-273 FS +26. +26. 1 .7 21. 21. .1 .1 KQ-70-274(l) -21.4 -21.6 36.8 36.5 KQ-70-274(2) ( -17.8 -18.1 34.4 34.4 KQ-70-274(3) -11.0 24. 4 KQ-70-274(4) . -17.7 -17.7 19. 19. 4 2 1 Sample c o l l e c t i o n by A.J. S i n c l a i r and A. Bentzen. 2 Sample c o l l e c t i o n by R.V. Kirkham. 3 C h a l c o c i t e - b o r n i t e m i x t u r e a n a l y z e d . A b b r e v i a t i o n s : VS = v e i n s u l f i d e ; FS = s u l f i d e a l o n g f r a c t u r e s ; py = p y r i t e ; cp = c h a l c o p y r i t e ; cc = c h a l c o c i t e ; bo = b o r n i t e . 103 SULFIDES IN MASSIVE ORE 1 1 — — © 1 1 © 1 1 i 1 0 1 * fit) « ~t t- 9- 1 H i——L-a— 1 • — i i 1 J I 1 I I I-1-0 -0-5 0 0-5 10 SULFIDES IN GABBRO i 0 1 i o--1-0 -0-5 0-5 1-0 A£34S (po-cpy) F i g u r e 3. P a r t i t i o n i n g o f s u l f u r i s o t o p e s i n the p a i r p y r r h o t i t e -c h a l c o p y r i t e from W e l l g r e e n n i c k e l - c o p p e r d e p o s i t . Each m i n e r a l p a i r i s taken from a s i n g l e hand specimen. Bar l e n g t h r e p r e s e n t s a n a l y t i c a l p r e c i s i o n a t the 95 p e r c e n t c o n f i d e n c e l e v e l ( i . e . +0.4 perm i l S ) . Each p l o t t e d p o i n t r e p r e s e n t s the d i f f e r e n c e i n i s o t o p i c c o m p o s i t i o n between p y r r h o t i t e and c h a l c o p y r i t e . 104 f a c t o r ( A c ^ 3 4 S p 0 ) appears t o have a v a l u e n e a r , and t o be randomly d i s t r i b u t e d about, z e r o , and c o n s e q u e n t l y , i s not s u i t a b l e as a b a s i s f o r temperature i n t e r p r e t a t i o n s . NICKEL-COPPER DEPOSITS N i c k e l - c o p p e r s u l f i d e d e p o s i t s o c c u r a t o r near the base o f gabbro-u l t r a m a f i c s i l l s a t W e l l g r e e n , A r c h Creek, and Canalask p r o p e r t i e s . The g e n e r a l g e o l o g y o f t h e W e l l g r e e n example i s t y p i c a l and i s shown i n F i g u r e 4. The complexes a r e l a r g e l y p e r i d o t i t i c a t W e l l g r e e n and A r c h Creek ( Q u i l l Creek Complex) and d u n i t i c a t Canalask (White R i v e r Complex) (see Ch a p t e r 3 ) . Host r o c k s a t W e l l g r e e n i n c l u d e p e r i d o t i t e and a gabbro which appears to be a l a t e r i n t r u s i o n a l o n g the base o f the s i l l n ear a r e s t r i c t e d b a s a l d u n i t e u n i t (see F i g u r e 8 ) . Wall r o c k s i n c l u d e c h e r t y a r g i l l i t e and b a s a l t i c a n d e s i t e t u f f . I n t e r c u m u l u s s u l f i d e s a r e a b s e n t i n t h e r e s t r i c t e d d u n i t e u n i t , but whole rock g e o c h e m i s t r y shows 0.2 t o 0.3 weight p e r c e n t s u l f u r i n d u n i t e ( C h a p t e r 3 ) . S u l f i d e b l e b s a r e s p a r s e l y d i s s e m i n a t e d i n the p e r i d o t i t e , which c o n t a i n s 0.4 t o 0.9 weight p e r c e n t s u l f u r . H e a v i l y d i s s e m i n a t e d t o n e t - t e x t u r e s u l f i d e s o c c u r i n gabbro and massive ore o c c u r s i n pods a t the base o f the gabbro and by i t s e l f i n f a u l t c o n t a c t w i t h the base o f the p e r i d o t i t e . H o r n f e l s , c o n s i s t i n g o f pyroxene and p l a g i o c l a s e , forms a c o n t a c t a u r e o l e a few meters wide a t the p e r i d o t i t e -t u f f c o n t a c t . T h i s a u r e o l e i s p a t c h y and d i s c o n t i n u o u s due t o s h e a r i n g and minor f a u l t i n g a l o n g the u l t r a m a f i c c o n t a c t s . At c h e r t y a r g i l l i t e -massive ore c o n t a c t s a h o r n f e l s , c o n s i s t i n g o f p l a g i o c l a s e , h o r n b l e n d e , and minor pyroxene, forms a c o n t a c t a u r e o l e up t o 5 cm wide. X e n o l i t h s 105 sw l+I-'H G A B B R O INV -1 PERIDOTITE DISSEMINATED SULPHIDES / 7 'rChlK NE ] N E T - T E X T U R E D SULPHIDES / X / " T / ^M/^'^M^ BEDDING IN ARGILLITE /"",\ •> , ~ ~ ' d ^ J i h MASSIVE SULPHIDES HORNFELS ARGILLITE •1- .+ .H S C A L E ( C R O S S S E C T I O N L O O K I N G N W ) F i g u r e 4. Cross s e c t i o n o f s t r u c t u r a l r e l a t i o n s among gabbro, p e r i d o t i t e , and s u l f i d e ore types a t W e l l g r e e n Mine. Gabbro p o s t d a t e s p e r i d o t i t e and n i c k e l - c o p p e r s u l f i d e ore and i n c l u d e s fragments o f the s u l f i d e s . Compiled from s u r f a c e mapping and underground i n f o r m a t i o n . At Arch Creek and Canalask an o l i v i n e gabbro forms a b o r d e r phase t o the p e r i d o t i t e . 106 o f t u f f , a few meters a c r o s s and h o r n f e l s e d t o a pyroxene and p l a g i o c l a s e assemblage, o c c u r i n the lower p a r t o f the p e r i d o t i t e near i t s base, Development work on Well green i n d i c a t e d an e s t i m a t e d 749,845 tonnes o f o r e , c o n t a i n i n g 2.04 p e r c e n t n i c k e l and 1.42 p e r c e n t copper ( F i n d l a y , 1969). The grade o f the ore a c t u a l l y m i l l e d changed from 2.05 p e r c e n t n i c k e l and 1.35 p e r c e n t copper i n 1972 to 2.49 p e r c e n t n i c k e l and 1.45 p e r c e n t copper i n 1973. P e r i d o t i t e and an o l i v i n e gabbro b o r d e r phase a r e h o s t r o c k s a t Arch Creek p r o p e r t y . As a t Well g r e e n , w a l l r o c k s i n c l u d e both c h e r t y a r g i l l i t e and t u f f . Minor d i s s e m i n a t e d s u l f i d e s o c c u r w i t h i n the p e r i d o t i t e and d i s s e m i n a t e d t o n e t - t e x t u r e d s u l f i d e s a r e found i n the b o r d e r phase. M a s s i v e ore i s a t the base o f the s i l l . Patchy h o r n f e l s e d w a l l r o c k s and small x e n o l i t h s a r e the same as those found a t Well green. P e r i d o t i t e a t A r c h Creek c o n t a i n s 0.3 w e i g h t p e r c e n t s u l f u r and maximum grades i n the massive ore are 3 p e r c e n t n i c k e l and 1 p e r c e n t c o p p e r . Host r o c k s a t Canalask i n c l u d e p e r i d o t i t e and an o l i v i n e gabbro b o r d e r phase. The w a l l r o c k i s c h e r t y a r g i l l i t e w i t h d i s c o n t i n u o u s i n t e r c a l a t i o n s o f t u f f . S u l f i d e s a r e d i s s e m i n a t e d i n the p e r i d o t i t e , d i s s e m i n a t e d t o n e t - t e x t u r e d i n the o l i v i n e gabbro, and massive ore o c c u r s as pods i n c h e r t y a r g i l l i t e 180 m i n t o the f o o t w a l l . These ore pods a r e r i d d l e d w i t h s m a l l , rounded x e n o l i t h s o f c h e r t y a r g i l l i t e . C o n t a c t s o f the White R i v e r complex a r e s e v e r e l y f a u l t e d and x e n o l i t h s a r e a b s e n t i n exposed p a r t s o f the complex. Dunite i s the dominant rock type i n the White R i v e r s i l l and, a l t h o u g h b a r r e n o f megascopic s u l f i d e s , i t c o n t a i n s 0.2 w e i g h t p e r c e n t s u l f u r . Reserves o f 515,105 tonnes o f ore at 1.68 p e r c e n t n i c k e l were r e p o r t e d f o r Canalask ( S i n c l a i r and G i l b e r t , 1973). 107 A l l o f thes e d e p o s i t s have been i n t e r p r e t e d by E c k s t r a n d (1972) to have formed by magmatic i n j e c t i o n . S u l f u r I s o t o p e s i n the N i c k e l - C o p p e r D e p o s i t s S u l f u r i s o t o p i c c o m p o s i t i o n s o f many n i c k e l - c o p p e r d e p o s i t s a r e r e l a t i v e l y u n i f o r m and f a l l i n the range +4 t o -2 p e r m i l P 4 S , a v e r a g i n g about +1 p e r m i l ( F i g u r e 5 ) , ver y near the v a l u e o f the Canon D i a b l o m e t e o r i t i c s t a n d a r d (0 p e r m i l S u l f u r h a v i n g t h i s i s o t o p i c c o m p o s i t i o n i s c o n s i d e r e d t o be d e r i v e d l a r g e l y o r e n t i r e l y from the mantle (Shima et_ a l _ . , 1963; S t a n t o n , 1972; Ohmoto and Rye, 1979; Cheney, 1974). The s u l f i d e s i n c e r t a i n n i c k e l - c o p p e r d e p o s i t s , i n c l u d i n g N o r i l ' s k ( G o d l e v s k i i and G r i n e n k o , 1963; Vi n o g r a d o v and G r i n e n k o , 1966), Talnakh ( K o v a l e n k e r e_t a l _ . , 1975), and Duluth (Mainwaring and N a l d r e t t , 1977) 34 are d e c i d e d l y e n r i c h e d i n S, and a r e c o n s i d e r e d t o have e x p e r i e n c e d 34 c o n t a m i n a t i o n o f p r i m a r y manlte s u l f u r by i n c o r p o r a t i o n o f S - r i c h c r u s t a l s u l f u r from w a l l r o c k s . In c o n t r a s t , s u l f u r i n n i c k e l - c o p p e r d e p o s i t s o f the Kluane Ranges i s d i s t i n c t l y e n r i c h e d i n ^ S , h a v i n g l e s s than -2.0 p e r m i l Such v a l u e s cannot be acco u n t e d f o r s o l e l y by d e r i v a t i o n from the mantle. The most ob v i o u s a l t e r n a t i v e p o s s i b i l i t y i s t h a t mantle s u l f u r has been co n t a m i n a t e d by c r u s t a l s u l f u r h a v i n g more n e g a t i v e S 3 4 s v a l u e s . G e o l o g i c a l e v i d e n c e tends t o s u p p o r t the p o s s i b i l i t y o f contamina-t i o n . The presence o f c o u n t r y rock x e n o l i t h s i n h o s t magmatic ro c k s and i n the ore pods, and the e x i s t e n c e o f a c o n t a c t a u r e o l e i s e v i d e n c e f o r p o s s i b l e chemical exchange between w a l l rock and magma. Furthermore, w a l l -r o c k s through which the magmas and ore s have t r a v e r s e d , namely, S t a t i o n Creek b a s a l t i c a n d e s i t e and the T r a n s i t i o n Zone, c o n t a i n s i g n i f i c a n t 108. - 20 - 10 0 10 20 i i i t i f T ^ r T i — f r"> v i i i i i i y CANALASK ^ ARCH CREEK , J 4 QUSLL CREEK SUDBURY PORCUPINE AREA NIPISSING DIABASE COBALT SILL LEITCH SILL STILLWATER PAL ISADES SILL P U R C E L L G A B B R O PERIDOTITES, MAINE •SULFIDE INSIZWA < ^ G A B B R O DIABASE, EAST US. MAFICS, ULTRAMAFICS G A B B R O S , PERIDOTITES « •J. 1 A J * -I-20 - 10 0 10 20 S 3 4 s t F i g u r e 5. S u l f u r i s o t o p i c d a t a f o r Well g r e e n , Arch Creek, and Canalask n i c k e l - c o p p e r d e p o s i t s and f o r a s e l e c t i o n o f o t h e r g a b b r o i c and u l t r a -m a f i c i n t r u s i o n s . Data are from: Thode e t aj_. (1962); N a l d r e t t (1966); S t a n t o n ( 1 9 7 2 ) ; Shima e t al_. ( 1963); S m i t h e r i n g a l e and Jensen ( 1963). 109 amounts o f s u l f i d e t h a t c o u l d c o n s t i t u t e the s o u r c e o f c o n t a m i n a t i o n o f c r u s t a l s u l f u r . In o r d e r t o e v a l u a t e c o u n t r y rock s u l f u r as a p o s s i b l e contaminant o f magmatic s u l f u r , some knowledge o f w a l l r o c k s u l f u r i s o t o p i c c o m p o s i t i o n s i s e s s e n t i a l . S u l f u r I s o t o p e s i n I n t r u d e d Country Rocks S u l f u r i s o t o p i c c o m p o s i t i o n s o f s u l f i d e s i n S t a t i o n Creek Formation b a s a l t i c a n d e s i t e ( T a b l e 4 and F i g u r e 6) range from -0.4 (34 to +8.8 p e r m i l o S. These d a t a are d i s c u s s e d i n a l a t e r s e c t i o n . A c t u a l w a l l r o c k s o f the Kluane g a b b r o - u l t r a m a f i c complexes a r e p a r t o f the T r a n s i t i o n Zone between S t a t i o n Creek and Hasen Creek F o r m a t i o n s . S u l f u r i s o t o p e s f o r p y r i t e from the Lower Permian T r a n s i -t i o n Zone are e n r i c h e d i n the l i g h t e r i s o t o p e , w i t h v a l u e s o f -13.3, -22.2, -24.3, -35.9 p e r m i l 5 3 4 S ( T a b l e 4 ) . The data a re s p a r s e and the range o f s u l f u r i s o t o p i c c o m p o s i t i o n s i s l a r g e , n e v e r t h e l e s s , i t i s ap p a r e n t t h a t the s u l f u r i s o t o p i c r a t i o s f o r s e d i m e n t a r y p y r i t e near Well green and near Canalask a re c o n s i s t e n t w i t h a v a l u e o f +12 permil f o r seawater s u l f a t e i n Lower Permian time ( N i e l s e n , 1979). The i s o t o p i c v a l u e s a t Cana l a s k a r e about 35 p e r m i l l o w e r than seawater s u l f a t e , whereas v a l u e s a t Well green are about 25 p e r m i l lower. These s h i f t s i n i s o t o p i c c o m p o s i t i o n o f s e d i m e n t a r y p y r i t e a re comparable to those f o r s u l f i d e s i n e u x i n i c environments and s h a l l o w marine - b r a c k i s h water e n v i r o n m e n t s , r e s p e c t i v e l y ( s e e Ohmoto and Rye, 1979). F i e l d e v i d e n c e , which i n c l u d e s the p r e s e n c e o f o r g a n i c - r i c h s h a l e s , s i l t y m a t e r i a l , and f o s s i l i f e r o u s l i m e s t o n e w i t h a h i g h a r g i l l a c e o u s c o n t e n t , s u p p o r t t h i s i n t e r p r e t a t i o n o f T r a n s i t i o n Zone ro c k s b e i n g d e p o s i t e d i n a r e s t r i c t e d b a s i n , b r a c k i s h water environment. 110 - 3 0 - 2 0 - 1 0 0 10 ~ ~ l I 1 1 1 CANALASK 4 ARCH CREEK WELLGREEN • STATION CREEK VOLCANICS • • TRANSITION ZONE I 1 1 1 I I - 4 0 - 3 0 - 2 0 - 1 0 0 10 S 34s%0 F i g u r e 6 . S u l f u r i s o t o p i c c o m p o s i t i o n s f o r s u l f i d e s i n the C a n a l a s k , W e l l g r e e n , and Arch Creek n i c k e l - c o p p e r d e p o s i t s , and f o r s u l f i d e s i n c o u n t r y r o c k s ( v o l c a n i c r o c k s and the T r a n s i t i o n Zone o f S t a t i o n Creek F o r m a t i o n ) . I l l Development o f a C o n t a m i n a t i o n Model On the b a s i s o f c o u n t r y rock s u l f u r i s o t o p i c c o m p o s i t i o n s o n l y t h e p y r i t i c T r a n s i t i o n Zone would p r o v i d e the s o u r c e o f contaminant s u l f u r t o Kluane g a b b r o - u l t r a m a f i c complexes. One might s p e c u l a t e t h a t a metamorphic model o f c o n t a m i n a t i o n c o u l d e x p l a i n t h e s t r o n g l y n e g a t i v e i s o t o p i c v a l u e s i n the n i c k e l - c o p p e r s u l f i d e d e p o s i t s . Such a model would i n v o l v e the e q u i l i b r a t i o n o f s u l f u r i s o t o p e s between the n i c k e l - c o p p e r o r e s and w a l l rock p y r i t e through the medium o f metamorphic f l u i d s . Two problems w i t h t h i s model cause the w r i t e r t o r e j e c t i t . F i r s t , t he low s o l u b i l i t y o f s u l f u r i n aqueous f l u i d s and the r i c h c o n c e n t r a t i o n o f s u l f i d e i n the o r e s would r e q u i r e an u n r e a s o n a b l y l a r g e water t o rock r a t i o t o produce the o b s e r v e d " s h i f t " i n i s o t o p i c c o m p o s i t i o n s . F u r t h e r m o r e , e q u i l i b r a t i o n would be e x p e c t e d t o y i e l d d i s s e m i n a t e d s u l f i d e s w i t h more n e g a t i v e s u l f u r i s o t o p e s than the massive o r e , because o f the r e l a t i v e amounts o f s u l f u r t h a t must be i n f l u e n c e d by the metamorphic f l u i d s . Such a d i f f e r e n c e i n i s o t o p i c c o m p o s i t i o n between the d i s s e m i n a t e d and massive ore i s n o t p r e s e n t i n the Kluane d e p o s i t s . A d d i t i o n a l e v i d e n c e , i n v o l v i n g d e p l e t i o n h a l o e s and bulk a s s i m i l a t i o n , w i l l be p r e s e n t e d l a t e r t o show t h a t mechanisms o t h e r than superimposed metamorphic e q u i l i b r a t i o n are more l i k e l y c o n t r i b u t o r s t o s u l f u r c o n t a m i n a t i o n . C a l c u l a t i o n s o f the amount o f c o n t a m i n a t i o n o f magmatic s u l f u r by s e d i m e n t a r y s u l f u r t o produce e x i s t i n g d e p o s i t s have been attempted. The s e q u e n t i a l c a l c u l a t i o n s i n v o l v e , f i r s t , an e s t i m a t e o f t h e r e l a t i v e p r o p o r t i o n o f s u l f u r from the two s o u r c e s , and second, e s t i m a t e s o f the a v a i l a b i l i t y o f t o t a l contaminant s u l f u r . I s o t o p i c d a t a i n d i c a t e the amount o f c o n t a m i n a t i o n , based on: (1) an assumed 0 p e r m i l i s o t o p i c c o m p o s i t i o n f o r i n i t i a l magmatic s u l f u r ; (2) an assumed average c o n t e n t 112 o f contaminant s u l f u r ; and (3) no f r a c t i o n a t i o n . The q u a n t i t a t i v e e s t i m a t e o f t o t a l s u l f u r abundance i s based on: (1) an assumed s u l f u r c o n t e n t o f the magma equal t o t h a t i n the d u n i t e ; and (2) an assumed s u l f u r c o n t e n t o f s u r r o u n d i n g r o c k s i n the a u r e o l e zone. The s e q u e n t i a l c a l c u l a t i o n s , t h e r e f o r e , l e a d t o an e s t i m a t e o f the t h i c k n e s s o f a u r e o l e n e c e s s a r y t o p r o v i d e the r e q u i r e d s u l f u r from w a l l r o c k . Much o f the data f o r Well green and A r c h Creek d e p o s i t s c l u s t e r around -6 p e r m i l S 3 4S. An average v a l u e f o r s e d i m e n t a r y s u l f u r i s -19 p e r m i l . T h e r e f o r e , i s o t o p i c d a t a i n d i c a t e t h a t about 32 p e r c e n t o f s u l f u r i n the m i n e r a l d e p o s i t s was d e r i v e d from a d j a c e n t r o c k s . We know t h a t : (1) the d u n i t e a t W e l l g r e e n c o n t a i n s an average o f 0.25 weight p e r c e n t s u l f u r ; (2) the Q u i l l Creek complex averages about 200 m t h i c k near the W e l l g r e e n Mine; and (3) the volume p e r c e n t p y r i t e i n the T r a n s i t i o n Zone near W e l l g r e e n and A r c h Creek p r o p e r t i e s a v e r a g e s about 1.5 p e r c e n t . D e n s i t i e s o f the u l t r a m a f i c rock and the T r a n s i t i o n Zone s e d i m e n t a r y r o c k s a r e a p p r o x i m a t e l y 3.8 and 2.6 g / c c , r e s p e c t i v e l y . From the above dat a the c a l c u l a t e d w i d t h o f c o n t a c t zone ( d e p l e t i o n h a l o ) from which s u l f u r would have t o be scavenged i s about 11 m. P y r r h o t i t e i n p e r i d o t i t e a t Canalask has a s u l f u r i s o t o p i c c o m p o s i t i o n c34 o f -14.4 p e r m i l o S. An average i s o t o p i c v a l u e f o r s e d i m e n t a r y s u l f u r i s -29 p e r m i l . The degree o f c o n t a m i n a t i o n by s e d i m e n t a r y s u l f u r from a d j a c e n t r o c k s i s t h e r e f o r e about 50 p e r c e n t . We know t h a t : (1) the d u n i t e a t Canalask c o n t a i n s an average o f 0.1 weight p e r c e n t s u l f u r ; (2) the White R i v e r complex i s about 200 m t h i c k near the Canal a s k d e p o s i t ; and (.3) the volume p e r c e n t p y r i t e i n the T r a n s i t i o n Zone near C a n a l a s k averages about 3.0 p e r c e n t . D e n s i t i e s o f the two rock t y p e s a r e t he same as thos e used f o r the W e l l g r e e n - A r c h Creek c a s e . From 113 these data the c a l c u l a t e d width o f the c o n t a c t zone from which s u l f u r would have t o be scavenged i s about 5 m. C l e a r l y , e x t r a c t i o n o f s u l f u r from r e l a t i v e l y narrow h a l o e s can produce the a p p a r e n t l e v e l o f contamin-a t i o n . The e x i s t e n c e o f d i s c o n t i n u o u s l y p r e s e r v e d ( p a r t l y f a u l t - b o u n d e d ) c o n t a c t a u r e o l e s , a few meters a c r o s s , about t h e Kluane complexes i s a f u r t h e r i n d i c a t i o n t h a t t h e s e c a l c u l a t e d widths o f 11 and 5 m a r e r e a s o n a b l e g e o l o g i c a l l y . S u l f i d e s i n massive o r e pods a t C a n a l a s k , i n j e c t e d 180 m i n t o the f o o t w a l l r o c k s , have an average i s o t o p i c c o m p o s i t i o n o f -18.5 p e r m i l C 34 O S. I n j e c t i o n o f t h i s o r e a p p a r e n t l y r e s u l t e d i n f u r t h e r c o n t a m i n a t i o n o f the a l r e a d y -14.4 p e r m i l s u l f u r i n the magma, as i n d i c a t e d by a s i n g l e i s o t o p i c v a l u e f o r d i s s e m i n a t e d s u l f i d e s i n p e r i d o t i t e . About 28 p e r c e n t c o n t a m i n a t i o n o f -14.4 p e r m i l s u l f u r by p y r i t i c s u l f u r (-29 p e r m i l ) i s r e q u i r e d t o b r i n g massive o r e s u l f u r t o -18.5 p e r m i l . T h i s i s e q u i v a l e n t t o a t o t a l o f 64 p e r c e n t w a l l r o c k s u l f u r and 36 p e r c e n t mantle s u l f u r . The model assumes a bimodal d i s t r i b u t i o n t o s u l f u r i s o t o p i c v a l u e s . The average s i z e o f the p y r r h o t i t e - r i c h pods i s about 1 m by 1 m by 2 m and the average d e n s i t y i s e s t i m a t e d t o be about 4.5 g / c c . From the s e and e a r l i e r d a t a , c a l c u l a t i o n s show t h a t an average s i z e o r e pod would have t o scavenge s e d i m e n t a r y s u l f u r from a 5 cm wide c o n t a c t zone o f w a l l r o c k o v e r a d i s t a n c e o f 180 m. In view o f the abundance o f c h e r t y a r g i l l i t e i n c l u s i o n s i n the o r e pods, and the g e o l o g i c e v i d e n c e f o r m o b i l i z a t i o n o f s t i l l l i q u i d s u l f i d e s a f t e r s e t t l i n g a t the base o f the p e r i d o t i t e , such c o n t a m i n a t i o n seems r e a s o n a b l e t o the a u t h o r . The above c a l c u l a t i o n s o f c o n t a c t a u r e o l e widths from which s u l f u r was thought t o be scavenged were based on an assumption t h a t a l l s u l f u r i n t he d e p l e t i o n h a l o e s was c o n t r i b u t e d t o the o r e . T h i s assumption 1 1 4 i n v o l v e s r e l e a s e o f a l l s u l f u r from p y r i t e . A n o t h e r p l a u s i b l e mechanism i n v o l v e s i n c o n g r u e n t m e l t i n g o f p y r i t e t o p y r r h o t i t e p l u s s u l f u r . Complete a s s i m i l a t i o n o f p y r i t e by the u l t r a m a f i c magma may i n v o l v e a s u b s t a n t i a l volume o f c o u n t r y r o c k . From the f o r g o i n g c a l c u l a t i o n s i t i s e s t i m a t e d t h a t a volume o f w a l l r o c k equal t o o n e - t e n t h the volume o f the Q u i l l Creek complex would have t o be i n c o r p o r a t e d by the magma. H o r n f e l s e d i n c l u s i o n s o f t u f f a c e o u s rock o c c u r i n the lower p a r t o f the Q u i l l Creek complex. P y r i t e i s abs e n t i n t h e s e i n c l u s i o n s . A l t h o u g h i n t e r b e d d e d c h e r t y a r g i l l i t e s a r e a l s o p r e s e n t i n the i n t r u s i v e zone, no such i n c l u s i o n s appear i n the u l t r a m a f i c s i l l . However, i r r e g u l a r - s h a p e d d i k e - l i k e b o d i e s o f f e l s i t e , c o n s i s t i n g o f q u a r t z and f e l d s p a r , o c c u r w i t h i n t h e s i l l a t W e l l g r e e n . I t may be t h a t t h e s e d i k e s r e s u l t from m e l t i n g o f s i l i c e o u s c o u n t r y rock i n c l u s i o n s . D i s s e m i n a t e d p y r i t e i s c h a r a c t e r i s t i c o f T r a n s i t i o n Zone r o c k s , y e t both p y r i t e and p y r r h o t i t e a r e c o n s p i c u o u s l y a b s e n t i n w a l l r o c k s i m m e d i a t e l y a d j a c e n t t o the s u l f i d e - b e a r i n g Kluane complexes. A g r e a t e r i r o n o x i d e abundance i n w a l l r o c k s w i t h i n t he a u r e o l e , r e l a t i v e t o the r e g i o n a l norm, i s c i r c u m s t a n t i a l e v i d e n c e t h a t a l l t he s u l f u r may have been e x t r a c t e d from the a u r e o l e and c o n t r i b u t e d t o the magma. A l t h o u g h the above e v i d e n c e s u p p o r t s d e c o m p o s i t i o n o f p y r i t e and i n g e s t i o n o f i r o n , s u l f u r , and w a l l -r o c k i n t o the magma, the bulk c h e m i s t r y o f the Q u i l l Creek complex shows no o b v i o u s e f f e c t s o f c o n t a m i n a t i o n by l a r g e q u a n t i t i e s o f w a l l r o c k (see Chapter 3 ) . The second mechanism, i n v o l v i n g d i s s o c i a t i o n o f p y r i t e t o p y r r h o t i t e and s u l f u r , would r e s u l t i n p y r r h o t i t e d i s t r i b u t e d w i t h i n t he c o u n t r y r o c k s . However, p y r r h o t i t e has not been r e c o g n i z e d i n exposed w a l I r o c k . In c o n c l u s i o n , s u l f u r i n Kluane g a b b r o - u l t r a m a f i c s i l l s appears t o have been co n t a m i n a t e d by p y r i t i c s u l f u r d e r i v e d from s u r r o u n d i n g c o u n t r y 115 r o c k s d u r i n g o r more l i k e l y p r i o r t o s e p a r a t i o n o f an i m m i s c i b l e s u l f i d e l i q u i d . I n j e c t i o n o f t h i s a l r e a d y c o n t a m i n a t e d s u l f i d e l i q u i d i n t o f o o t w a l l r o c k s may have l e d t o f u r t h e r s u l f u r c o n t a m i n a t i o n , as i m p l i e d by the Cana l a s k d a t a . S i n c e e x t r a c t i o n o f s u l f u r from w a l l r o c k i n 5 t o 11 m wide zones m a r g i n a l t o the g a b b r o - u l t r a m a f i c complexes would be adequate t o produce o b s e r v e d i s o t o p i c r a t i o s , t he importance o f p y r i t e - b e a r i n g c o u n t r y r o c k s t o development o f massive n i c k e l - c o p p e r o r e becomes e v i d e n t . I f t he c o u n t r y r o c k s c o n t a i n e d no s u l f u r , the Kluane complexes would have c o n t i n u e d t o c r y s t a l l i z e s i l i c a t e m i n e r a l s and s u l f u r s a t u r a t i o n might not have been a t t a i n e d o r might have been reached much l a t e r i n the c r y s t a l l i z a t i o n sequence. M a s s i v e o r e pods c o u l d p r o b a b l y not have formed a t a l a t e s t a g e o f c r y s t a l l i z a t i o n i n the l a r g e l y c r y s t a l l i n e mush. C o n s e q u e n t l y , i n c o r p o r a t i o n o f c r u s t a l s u l f u r i n t o t h e magma may have been an i m p o r t a n t c o n t r o l i n the development o f massive n i c k e l -c o p p e r - p l a t i n u m s u l f i d e s , and i t i s p o s s i b l e t h a t no m i n e r a l i z a t i o n o f economic s i g n i f i c a n c e would have o c c u r r e d w i t h o u t t h i s c o n t a m i n a t i o n . Bimodal A s p e c t o f W e l l g r e e n S u l f u r I s o t o p e Data S u l f u r i s o t o p i c c o m p o s i t i o n s o f n i c k e l - c o p p e r s u l f i d e s i n the W e l l g r e e n d e p o s i t ( F i g u r e 7) can be i n t e r p r e t e d as two d i s t i n c t p o p u l a t i o n s c e n t e r e d a t about -3.5 p e r m i l and -6.0 p e r m i l o S. The attempt t o deter m i n e whether t h i s bimodal tendency was dependent on s p a t i a l d i s t r i b u t i o n was somewhat hampered by l a c k o f l o c a t i o n d a t a f o r some o f t he W e l l g r e e n underground samples (from s t o c k p i l e ; see T a b l e 3 ) . A l l s u r f a c e showings a t W e l l g r e e n and Ar c h Creek c o n t a i n s u l f u r w i t h i s o t o p i c c o m p o s i t i o n around -6.0 p e r m i l . Specimens from underground (both l o c a t e d and s t o c k p i l e ) show both -3.5 and -6.0 116 O N E A N A L Y S I S • CP POl PO MASSIVE ORE CPICPI CP CP PO PO PO SULFIDES IN GABBRO CP CP PN CP CP PN PN 9 fl^V flBV jii _ PN PN PO PO PO to* N H PO PO PO PO PO PN| 1 1 1 1 I L -8 -7 -6 -5 -4 -3 s3 4s& F i g u r e 7. S u l f u r i s o t o p i c c o m p o s i t i o n s f o r n i c k e l - c o p p e r s u l f i d e ore i n both the gabbro and massive ( i n c l u d i n g one sample o f d i s s e m i n a t e d p y r r h o t i t e i n p e r i d o t i t e ) f o r W e l l g r e e n and Arch Creek d e p o s i t s . The f i v e Arch Creek a n a l y s e s a r e d i s t i n g u i s h e d by heavy b o r d e r s . C r o s s e d boxes i n d i c a t e samples from s u r f a c e e x p o s u r e s : o t h e r s from underground o r s t o c k p i l e . S u l f i d e m i n e r a l s : p o = p y r r h o t i t e ; c p = c h a l c o p y r i t e ; pn= p e n t l a n d i t e . 117 C 34 o S, a l t h o u g h more specimens show the former v a l u e . An i d e a l i z e d c r o s s s e c t i o n a l view o f the d i s t r i b u t i o n o f t h e s e two p o p u l a t i o n s i s shown i n F i g u r e 8. The more n e g a t i v e v a l u e s o f s u r f a c e samples might, a t f i r s t , be thought due t o f r a c t i o n a t i o n a s s o c i a t e d w i t h s u r f a c e o x i d a t i o n , but i n g e n e r a l , the s u r f a c e o x i d a t i o n p r o c e s s does not r e s u l t i n measurable f r a c t i o n a t i o n (Ohmoto and Rye, 1979). The s u l f u r i s o t o p i c v a l u e s o f s u l f i d e s i n the gabbro a t W e l l g r e e n (a l a t e r i n t r u s i o n a l o n g the base o f the p e r i d o t i t e ) have a bimodal d i s t r i b u t i o n p a t t e r n comparable t o t h a t o f massive ore r e l a t e d t o the u l t r a m a f i c r o c k s . The p r o b a b l e e x p l a n a t i o n i s t h a t s u b s t a n t i a l amounts o f the p r e - e x i s t i n g s u l f i d e ore pods a r e e n g u l f e d and p a r t l y melted by the gabbro w i t h o u t s i g n i f i c a n t m o d i f i c a t i o n o f the i s o t o p i c v a l u e s . The "magmatic" t e x t u r e s o f s u l f i d e s i n the younger gabbro a r e c e r t a i n l y c o n s i s t e n t w i t h t h i s i n t e r p r e t a t i o n as i s the c l o s e s p a t i a l a s s o c a t i o n o f g a b b r o i c s u l f i d e s w i t h s u l f i d e s d i r e c t l y r e l a t e d t o the p e r i d o t i t e . The s u l f u r i s o t o p e d a t a f o r s u l f i d e s i n both t h e Q u i l l Creek complex ( p e r i d o t i t e and d u n i t e ) and the younger gabbro appear t o be bimodal as shown i n F i g u r e 7. Whether o r not t h i s i s t r u e has a marked s i g n i f i c a n c e t o the i n t e r p r e t a t i o n o f the d a t a . For example, i f a s i n g l e p o p u l a t i o n i s assumed we have a p p a r e n t l y sampled i t i n a h i g h l y b i a s e d f a s h i o n . The s u b s t a n t i a l s c a t t e r o f v a l u e s i s thus s u g g e s t i v e o f v a r i a b l e c o n t a m i n a t i o n l o c a l l y w i t h o u t homogenization t h r o u g h o u t the magma chamber and i m p l i e s a s i n g l e continuum o f s u l f i d e s e g r e g a t i o n t o form the known d e p o s i t s . In s u p p o r t o f t h i s , note t h a t one o f the samples (El-71-526) c o n s i s t s o f c o e x i s t i n g s u l f i d e s w i t h s u l f u r i s o t o p i c c o m p o s i t i o n s t h a t p l o t i n both p o p u l a t i o n s . I f t h e d i s t r i b u t i o n o f v a l u e s i s taken t o be t r u l y bimodal as NW ARCH CK. WELLGREEN SE -6-0 - 60 W « j T E _ _ _ ^ 3 . ^ . t o -6.o HYPOTHETICAL FEEDER (jfy F i g u r e 8. I d e a l i z e d d i s t r i b u t i o n o f average s u l f u r i s o t o p e v a l u e s f o r W e l l g r e e n and Arch Creek d e p o s i t s o f the Q u i l l Creek p e r i d o t i t i c complex, on a r e c o n s t r u c t e d c r o s s s e c t i o n o f the complex. 119 i m p l i e d i n F i g u r e 7, the i n t e r p r e t a t i o n i s c o n s i d e r a b l y more complex. One e x p l a n a t i o n f o r the bimodal d i s t r i b u t i o n o f s u l f u r i s o t o p i c c o m p o s i t i o n s i n the W e l l g r e e n d e p o s i t may be v a r i a t i o n s i n the i s o t o p i c c o m p o s i t i o n o f w a l l r o c k s u l f u r . I t i s p o s s i b l e t h a t d i f f e r e n t l e v e l s w i t h i n the T r a n s i t i o n Zone c o n t a i n p y r i t e w i t h d i f f e r e n t i s o t o p i c c o m p o s i t i o n s . The two p o p u l a t i o n s i n the n i c k e l - c o p p e r o r e s may t h e r e f o r e i n d i c a t e two d i f f e r e n t s o u r c e l e v e l s f o r scavenged s u l f u r . F o r example, s e d i m e n t a r y s u l f u r w i t h l e s s n e g a t i v e i s o t o p i c v a l u e s ( i . e . , -13.3 p e r m i l ) may c o r r e s p o n d t o ore s u l f u r o f -3.5 p e r m i l w h i l e s e d i m e n t a r y s u l f u r w i t h s t r o n g l y n e g a t i v e v a l u e s ( i . e . , -24.3 p e r m i l ) may c o r r e s p o n d t o ore s u l f u r o f -6 p e r m i l Our data a r e s u f f i c i e n t l y s p a r s e t h a t t h i s s u g g e s t i o n cannot be t e s t e d t h o r o u g h l y . I f t h i s model i s t r u e i t i m p l i e s l a c k o f complete m i x i n g o f s u l f u r i n the magma f o l l o w i n g c o n t a m i n a t i o n and p r i o r t o s u l f i d e i m m i s c i b i l i t y . A n o t h e r p o s s i b i l i t y i s t h a t the bimodal d i s t r i b u t i o n o f s u l f u r i s o t o p e v a l u e s a t W e l l g r e e n i s due t o a two-stage c o n t a m i n a t i o n p r o c e s s , t h a t i s , two main e p i s o d e s o f c o n t a m i n a t i o n . An e a r l y s t a g e o f f a i r l y homogeneous s u l f u r c o n t a m i n a t i o n i s e n v i s a g e d a t the time o f emplacement o f t he u l t r a m a f i c magma ( s u l f i d e s w i t h -3.5 p e r m i l ) and a second s t a g e l a t e r i n t h e c r y s t a l l i z a t i o n h i s t o r y o f the magma ( s u l f i d e s w i t h -6.0 p e r m i l ) . These two s t a g e s would perhaps c o r r e s p o n d , r e s p e c t i v e l y , t o (1) i n i t i a l emplacement o f the magma, and (2) l a t e r a l f l o w . C e r t a i n l y , t h e r e a r e d i s t i n c t s t a g e s i n the c r y s t a l l i z a t i o n h i s t o r y o f the Q u i l l Creek complex. I t seems c l e a r t h a t a t l e a s t one p e r i o d o f w a l l r o c k c o n t a m i n a t i o n has o c c u r r e d . Whether o r not a second d i s t i n c t phase o f c o n t a m i n a t i o n took p l a c e cannot be c o n c l u d e d w i t h c e r t a i n t y . 120 SULFIDES IN STATION CREEK FORMATION R e l a t i v e l y few m i n e r a l o c c u r r e n c e s w i t h economic p o t e n t i a l a r e known i n r o c k s o f the S t a t i o n Creek Formation a l t h o u g h one p r o s p e c t , the P i c k h a n d l e Lake p r o p e r t y has been the s u b j e c t o f e x p l o r a t i o n and has been mapped i n d e t a i l by the w r i t e r i n 1976 ( F i g u r e 9 ) . D e s p i t e the low abundance o f m i n e r a l p r o s p e c t s , d i s s e m i n a t e d p y r i t e and t h i n con-f o r m a b l e l a y e r s o f massive p y r i t e a r e common i n t h i s p r e d o m i n a n t l y v o l c a n i c u n i t . At the P i c k h a n d l e p r o p e r t y ( F i g u r e 1) p y r i t e , c h a l c o p y r i t e , and p y r r h o t i t e o c c u r w i t h i n f l o w and t u f f a c e o u s r o c k s o f b a s a l t i c a n d e s i t e c o m p o s i t i o n i n the lower p a r t o f S t a t i o n Creek F o r m a t i o n . P y r i t e and, t o a l e s s e r e x t e n t , c h a l c o p y r i t e a r e d i s s e m i n a t e d as s m a l l , i n d i v i d u a l g r a i n s o r o c c u r as t h i n , massive l e n s e s e l o n g a t e p a r a l l e l t o bedding. C h a l c o p y r i t e and minor amounts o f p y r r h o t i t e , t o g e t h e r w i t h q u a r t z , c a l c i t e , and e p i d o t e , form s m a l l , d i s c o n t i n u o u s s t r i n g e r s and l a r g e r v e i n s , which g e n e r a l l y c r o s s c u t bedding and f o l i a t i o n . These s u l f i d e s a r e thought t o be o f s y n g e n e t i c o r i g i n and t o have undergone r e g i o n a l metamorphism o f g r e e n s c h i s t f a c i e s . That i s , s u l f i d e m i n e r a l s have i n p a r t r e c r y s t a l 1 i z e d i n s i t u , and i n p a r t undergone l o c a l m o b i l i z a t i o n i n t o q u a r t z - c a r b o n a t e - e p i d o t e v e i n s . S u l f u r i s o t o p i c c o m p o s i t i o n s f o r s u l f i d e s from P i c k h a n d l e P r o p e r t y ( T a b l e 4) span a narrow range from -0.4 t o +8.8 p e r m i l <S34S w i t h an approximate average o f +3 p e r m i l . V a l u e s f o r d i s s e m i n a t e d s u l f i d e s a r e +1.1 and +8.8 p e r m i l , whereas v a l u e s f o r v e i n s u l f i d e s range from c34 -0.4 t o +6.9 p e r m i l d S. D e s p i t e the l i m i t e d d a t a i t appears t h a t the ranges i n i s o t o p i c c o m p o s i t i o n s o f s u l f u r a r e the same f o r the two forms C u - F e SULFIDES DISSEMINATED &AS LENSES F i g u r e 9. Geology o f p a r t o f the P i c k h a n d l e p r o p e r t y , Kluane Ranges, showing r e l a t i o n o f m i n e r a l o c c u r r e n c e s (both s t r a t i f o r m and c r o s s c u t t i n g ) to the rock u n i t s . 122 o f s u l f i d e o c c u r r e n c e . Many s t r a t i f o r m massive s u l f i d e d e p o s i t s a s s o c i a t e d w i t h submarine v o l c a n i s m have & 3 4S v a l u e s i n the range -10 t o +20 p e r m i l w i t h a C 3 4 mean i n the range 0 t o +10 p e r m i l o S (Ohmoto and Rye, 1979). I t appears t h a t d a t a f o r P i c k h a n d l e s u l f i d e s a r e i n k e e p i n g w i t h t h i s p a t t e r n and t h a t metamorphism has a p p a r e n t l y had, a t most, a minor e f f e c t on the i s o t o p i c c o m p o s i t i o n . A n e c e s s a r y i m p l i c a t i o n o f t h i s l a t t e r statement i s t h a t o n l y l o c a l m o b i l i z a t i o n and m i x i n g o f v o l c a n i c s u l f i d e s o c c u r r e d d u r i n g r e g i o n a l metamorphism. These s u l f u r i s o t o p e d a t a i n d i c a t e t h a t metamorphism has o p e r a t e d e s s e n t i a l l y i n a c l o s e d system w i t h r e g a r d t o s u l f u r i n S t a t i o n Creek F o r m a t i o n . SULFIDES IN NIKOLAI GREENSTONE Copper s u l f i d e o c c u r r e n c e s have been known i n N i k o l a i b a s a l t s s i n c e b e f o r e the t u r n o f the c e n t u r y and e a r l y thorough d e s c r i p t i o n s appeared i n t h e l i t e r a t u r e s h o r t l y a f t e r t h e i r d i s c o v e r y ( e . g . Knopf, 1910). The o c c u r r e n c e s c o n s i s t p r e d o m i n a n t l y o f e p i g e n e t i c c h a l c o c i t e -b o r n i t e w i t h o r w i t h o u t l e s s e r and commonly minor amounts o f n a t i v e c o p p e r , p y r i t e , and r a r e l y o t h e r m i n e r a l s . I n v a r i a b l y t h e s e c o n c e n t r a -t i o n s o c c u r i n zones t h a t o r i g i n a l l y were open s p a c e s , such as amygdules, f l o w b r e c c i a s , c r a c k l e zones, and s h e a r zones and f r a c t u r e s t h a t c r o s s -c u t i n d i v i d u a l f l o w s and groups o f f l o w s i n the N i k o l a i . There i s some i n d i c a t i o n t h a t a s u b s t a n t i a l p r o p o r t i o n o f the n a t i v e copper p r e d a t e s t h e s u l f i d e s ( e . g . Kirkham, 1972; S i n c l a i r e t a l _ . , 1979) a l t h o u g h the e v i d e n c e i s c i r c u m s t a n t i a l . Copper s u l f i d e o c c u r r e n c e s o f t h i s t y p e o c c u r i n c l o s e p r o x i m i t y t o the famous Kennecott copper d e p o s i t s i n the 123 C h i t i s t o n e Limestone which i m m e d i a t e l y o v e r l i e s the N i k o l a i , and v a r i o u s a u t h o r s ( S i 1 berman e t a l _ . , 1980; S i n c l a i r _et_aJL , 1979) have s p e c u l a t e d t h a t t h e s e c o p p e r d e p o s i t s have formed as p a r t o f the g e n e r a l p r o c e s s t h a t produced copper s u l f i d e d e p o s i t s t h r o u g h o u t the N i k o l a i b a s a l t s . One o f the l a r g e r and more t h o r o u g h l y s t u d i e d o f the d e p o s i t s w i t h i n the N i k o l a i Greenstone i s the S i l v e r C i t y ( o r D i s c o v e r y ) d e p o s i t ( S i n c l a i r ejt a l _ . , 1979) ( F i g u r e 10). Here f a i r l y abundant n a t i v e copper o c c u r s i n c r u d e l y t a b u l a r zones p a r a l l e l t o the v o l c a n i c f l o w s , whereas c o p p e r s u l f i d e c o n c e n t r a t i o n s a r e more e r r a t i c i n t h e i r d i s t r i b u t i o n and p r e s e n t t h r o u g h o u t more o f the exposed s e c t i o n ( F i g u r e 2 ) . The p a r a g e n e t i c sequence a t the S i l v e r C i t y d e p o s i t ( S i n c l a i r ejt a j_., 1979) i s : p y r i t e ( o l d e s t ) - c h a l c o p y r i t e - b o r n i t e - c h a l c o c i t e -n a t i v e copper - c u p r i t e ( y o u n g e s t ) . T h i s p a r a g e n e s i s shows t h a t s u l f u r f u g a c i t y d e c r e a s e d and oxygen f u g a c i t y i n c r e a s e d through the d e p o s i t i o n a l sequence ( R o b e r t s o n , 1975). S u l f i d e s a r e d o m i n a n t l y i n v e i n s and a s s o c i a t e d s p a t i a l l y w i t h metamorphic m i n e r a l s such as c a l c i t e , e p i d o t e , p r e h n i t e , and p u m p e l l y i t e . C e r t a i n t e x t u r e s o f the copper s u l f i d e s , i n t e r p r e t e d as e x s o l u t i o n , s u g g e s t a minimum temperature o f f o r m a t i o n i n the range 200° t o 300°C ( S i n c l a i r ejt a j _ . , 1979). C a l c u l a t e d ore f l u i d t e m p e r a t u r e s from oxygen i s o t o p e d a t a from q u a r t z and e p i d o t e i n t h r e e c o p p e r - b e a r i n g v e i n s i n nearby A l a s k a g i v e an approximate temperature o f 200°C ( S i l b e r m a n e t a l . , 1980). S i n c l a i r et_ aj_. (1979) i n t e r p r e t f o r m a t i o n o f the s u l f i d e s d u r i n g r e g i o n a l metamorphism i n an open system w i t h c h e m i c a l parameters o f the o r e - f o r m i n g f l u i d s c h a n g i n g w i t h t i m e . T h i s m e t a m o r p h i c - s e g r e g a t i o n o r i g i n i s i n agreement w i t h the c a l c u l a t e d ore f l u i d temperature and c 18 h 0 o f a p p r o x i m a t e l y +1 p e r m i l o b t a i n e d by S i l b e r m a n e_t a l _ . , (1980). 124 [Figure 10. G e o l o g i c c r o s s s e c t i o n f o r S i l v e r C i t y p r o p e r t y . P r o j e c t e d v e r t i c a l s e c t i o n through 2900 a d i t . C o n t a c t i n f o r m a t i o n w i t h i n 46 m (150 f e e t ) o f the plane o f s e c t i o n was p r o j e c t e d t o the plane o f s e c t i o n a l o n g the average s t r i k e d i r e c t i o n . Zone o f g r e a t e r than 0.1 p e r c e n t copper i s a l s o i n c l u d e d . M o d i f i e d from S i n c l a i r ejt al_. (1979). 125 S u l f u r i s o t o p i c c o m p o s i t i o n s f o r N i k o l a i s u l f i d e s a t S i l v e r C i t y p r o p e r t y range from +22.1 p e r m i l f o r p y r i t e t o -17.9 p e r m i l f o r c h a l c o -c i t e ( F i g u r e 11). T h e r e f o r e , i n g e n e r a l , s u l f u r became more e n r i c h e d •30 i n S as d e p o s i t i o n p r o c e e d e d . P o s s i b l e causes o f t h i s tremendous range i n s u l f u r i s o t o p i c c o m p o s i t i o n i n c l u d e : (1) changes i n the chemi-c a l c o n d i t i o n s (oxygen f u g a c i t y and pH) d u r i n g s u l f i d e d e p o s i t i o n ; and (2) m u l t i p l e s o u r c e s o f s u l f u r . C o n s i d e r the range i n s u l f u r i s o t o p i c c o m p o s i t i o n o f c h a l c o c i t e , which i s +16.8 t o -17.9 p e r m i l <534s (T a b l e 5 ) . P y r i t e r e p r e s e n t s i n i t i a l s u l f i d e d e p o s i t i o n . I t o c c u r s i n v e i n l e t s and as d i s s e m i n a t e d g r a i n s and i n p a r t has r e p l a c e d m a g n e t i t e . I t has an i s o t o p i c c o m p o s i t i o n o f +22.1 p e r m i l and s i n c e p y r i t e i s the f i r s t s u l f i d e t o be d e p o s i t e d t h i s v a l u e i s a b e s t e s t i m a t e o f the s t a r t i n g i s o t o p i c c o m p o s i t i o n o f s u l f u r i n the o r e - f o r m i n g f l u i d s . From the work o f S i n c l a i r e t a l . (1979) and S i l b e r m a n ejt al_. (1980) we s e l e c t 250°C as an average temperature o f ore f o r m a t i o n . C o n s i s t e n c y o f the gangue m i n e r a l o g y t h r o u g h o u t s u l f i d e d e p o s i t i o n does not l e n d i t s e l f t o d e t e r m i n a t i o n o f a l i m i t i n g range i n pH. T h e r e f o r e , a c o n s t a n t o r n e a r l y c o n s t a n t pH o f about 6 i s assumed f o r s i m p l i c i t y . At 250°C and a pH o f 6, the dominant s u l f u r s p e c i e s i n the system i s h^S ( F i g u r e 12). The i s o t o p i c e n r i c h m e n t f a c t o r , A 6 3 4 S . . . , a t 250°C i s +0.3 p e r m i l (see Robinson and Ohmoto, r^b-py 1973). T h e r e f o r e , the i s o t o p i c c o m p o s i t i o n o f the sum o f the s u l f u r c 14 s p e c i e s {a S £ S ^ n's +22.4 p e r m i l . T h i s i s w i t h i n the range o f v a l u e s f o r s u l f u r i n seawater d u r i n g T r i a s s i c time ( c f . N i e l s e n , 1979). Data from Ohmoto (1972) show the i n f l u e n c e o f oxygen f u g a c i t y and pH a t 250°C on the i s o t o p i c c o m p o s i t i o n o f s u l f u r i n H 2S ( F i g u r e 10). C 34 A t a pH o f 6, and o v e r an i n c r e a s e o f f n by f o u r l o g u n i t s , o S,, -30 -20 -10 0 10 20 30 • m m a m y a r t M i> mi mm • JOHOBO MINES SILVER CITY m I B s s i B i I a e E B H QUILL CREEK MINES B B B ALICE LAKE MINES BisiiBgiEttff i i i^^ KENNECOTT HYDROTHERMAL mm^m^mm^mmmmmiiss^ii^m^mHm^m^mmmmmmm SULFIDES -30 -20 -10 0 10 20 30 S 34Q </ O /oo F i g u r e 11. S u l f u r i s o t o p i c c o m p o s i t i o n s f o r copper d e p o s i t s i n the N i k o l a i Greenstone a t S i l v e r C i t y , Q u i l l Creek Mines, A l i c e Lake Mines p r o p e r t i e s , and Johobo Mine. S u l f u r i s o t o p i c c o m p o s i t i o n s f o r the K e n n e c o t t d e p o s i t i n A l a s k a (Tupper, 1960) and f o r hydrothermal v e i n s d e p o s i t s i n g e n e r a l ( N i e l s e n , 1979) are i n c l u d e d f o r comparison. i 2 7 J __J I 1 I - J L -2 4 6 8 10 F i g u r e 12. S t a b i l i t i e s o f predominant aqueous s u l f u r - c o n t a i n i n g s p e c i e s as f u n c t i o n s o f fo2 and pH a t 250°C, and w i t h superimposed s t a b i l i t y f i e l d s f o r p y r i t e , m a g n e t i t e , and h e m a t i t e . (Taken from Ohmoto, 1972, p. 559 and B a r n e s , 1979, p. 444). 128 changes from +22.1 t o -4.1 p e r m i l . Knowing t h a t A O 3 4 S u c a t 250°C no. J - C C i s about +4.2 p e r m i l , a c o r r e s p o n d i n g range i n i s o t o p i c c o m p o s i t i o n f o r c h a l c o c i t e becomes +18.2 t o -8.3 p e r m i l ( F i g u r e 13). However, S i l v e r C i t y c h a l c o c i t e v a r i e s from +16.8 t o -17.9 p e r m i l , (34 s u g g e s t i n g t h a t even though much o f the v a r i a t i o n i n o S v a l u e s can be e x p l a i n e d by v a r i a t i o n s i n pH and Eh o f the o r e - f o r m i n g f l u i d s , a n o t h e r s o u r c e o f v a r i a b i l i t y i s r e q u i r e d . We c o n s i d e r v a r i a b l e i s o t o p i c c o m p o s i t i o n o f i n i t i a l s u l f u r as a l i k e l y p o s s i b i l i t y . For example, h i g h p o s i t i v e P 4 S v a l u e s a r e c o n s i s t e n t w i t h T r i a s s i c (34 seawater s u l f a t e as a main s o u r c e , whereas h i g h n e g a t i v e o S v a l u e s s u g g e s t the p o s s i b i l i t y o f Permian seawater s u l f a t e ( i n u n d e r l y i n g Hasen Creek Formation) as the p r i n c i p a l s u l f u r s o u r c e . F u r t h e r s p e c u l a t i o n i s premature u n t i l i s o t o p i c d a t a are a v a i l a b l e f o r s u l f i d e s i n a v a r i e t y o f p o s s i b l e s o u r c e r o c k s . In summary, the range i n s u l f u r i s o t o p i c c o m p o s i t i o n o f c h a l c o c i t e can be e x p l a i n e d by o r e - f o r m i n g f l u i d s i n an open system, c o n t a i n i n g C34 s u l f u r w i t h o S equal t o +22 o r t o +12 p e r m i l , and w i t h i n c r e a s i n g oxygen f u g a c i t y ( o r i n c r e a s i n g oxygen f u g a c i t y and pH) w i t h time. I t seems r e a s o n a b l e t o c o n c l u d e t h a t the o r e - f o r m i n g f l u i d s were the r e s u l t o f d e - w a t e r i n g o f Hasen Creek s e d i m e n t a r y r o c k s and p o s s i b l y the lowermost N i k o l a i b a s a l t f l o w s , which a r e b e l i e v e d t o be subaqueous. Data f o r Q u i l l Creek Mines, A l i c e Lake Mines, and Johobo p r o p e r t i e s a r e s p a r s e , but f a l l w i t h i n the g e n e r a l range o f d a t a f o r S i l v e r C i t y p r o p e r t y and t h u s , p r o b a b l y had comparable h i s t o r i e s . CONCLUSIONS The s t u d y o f s u l f u r i s o t o p e s c o n t r i b u t e s s i g n i f i c a n t l y t o an 129 F i g u r e 13. I n f l u e n c e o f f g ? and pH on the i s o t o p i c c o m p o s i t i o n o f s u l f u r s p e c i e s . T=250°C, 1 = 1.0, ana c ^ S r ^ - +22.4 p e r m i l . Heavy arrow i n d i c a t e s a p o s s i b l e path o f change i n the chemical parameters f o r the o r e - f o r m i n g f l u i d s d u r i n g m i n e r a l d e p o s i t i o n . ( M o d i f i e d a f t e r Ohmoto, 1972). 130 u n d e r s t a n d i n g o f the g e n e s i s o f copper s u l f i d e d e p o s i t s i n the Kluane Ranges and a d j o i n i n g a r e a s . The data g e n e r a l l y c o n f i r m g e o l o g i c i n t e r p r e t a t i o n s o f g e n e s i s and go beyond t h i s t o p r o v i d e i n s i g h t i n t o s o u r c e s o f s u l f u r and c e r t a i n a s p e c t s o f i t s h i s t o r y d u r i n g m i n e r a l d e p o s i t i o n . Diagrammatic o u t l i n e s o f the t h r e e models emerging from t h i s s t u d y a r e shown i n F i g u r e 14. Kluane n i c k e l - c o p p e r s u l f i d e d e p o s i t s have i s o t o p i c v a l u e s s i g n i f i c a n t l y more n e g a t i v e than do o t h e r n i c k e l - c o p p e r s u l f i d e b o d i e s a s s o c i a t e d w i t h g a b b r o - u l t r a m a f i c complexes. The s u l f u r i s o t o p i c c o m p o s i t i o n s o f Kluane n i c k e l - c o p p e r d e p o s i t s a re almos t c e r t a i n l y the p r o d u c t o f s u b s t a n t i a l c o n t a m i n a t i o n o f the u l t r a m a f i c magma by s u l f u r from w a l l r o c k s i n the T r a n s i t i o n Zone a t the top o f the Lower Permian S t a t i o n Creek Formation. The s u l f u r i s o t o p e d a t a f o r W e l l g r e e n s u l f i d e s c o n s t i t u t e one o r perhaps two p o p u l a t i o n s , and r e p r e s e n t a t l e a s t one major time i n t e r v a l o f c o n t a m i n a t i o n o f the Q u i l l Creek u l t r a m a f i c complex by s u l f u r from a d j a c e n t w a l l r o c k s . Such c o n t a m i n a t i o n o c c u r r e d p r i o r t o o r d u r i n g s e g r e g a t i o n o f an i m m i s c i b l e s u l f i d e l i q u i d . The i s o t o p i c data f o r the massive o r e pods a t Canalask p r o p e r t y s u g g e s t f u r t h e r c o n t a m i n a t i o n o f the s t i l l l i q u i d s u l f i d e s d u r i n g and/or a f t e r i n j e c t i o n i n t o f o o t w a l l r o c k s 180 m removed from the n e a r e s t o c c u r r e n c e o f p a r e n t u l t r a m a f i t e . Three mechanisms o f s u l f u r c o n t a m i n a t i o n o f the magmas are c o n s i d e r e d . T o t a l i n g e s t i o n o f p y r i t e by bulk w a l l r o c k a s s i m i l a t i o n i s a p o s s i b i l i t y f o r which some e v i d e n c e e x i s t s , but o t h e r p r o c e s s e s may have had an imp o r t a n t c o n t r i b u t i o n . S u l f u r c o u l d be r e l e a s e d from p y r i t e i n the w a l l r o c k by (1) i n c o n g r u e n t m e l t i n g o f p y r i t e , o r (2) t o t a l d i s s o c i a t i o n o f p y r i t e . In the l a t t e r case a 5 t o 10 m wide d e p l e t i o n h a l o around 131 STAGE 2 GRADAT10NAL CONTACT ZONE \ \ ^ \ ^ ^ D U N I T E _ ^ ^ T A G E 1 ' X A A a A A A A A A A A A A A 4 A A A 4 4/-;. A a 4 A A A 4 4 4 4 4 * * 4 4 4 4-1 A 4 A A 4 4 4 A A 4 4 a A A 4 4 4 A A 4 4 4,A 4 4 4 0 F i g u r e 14. Schematic diagrams f o r g e n e r a t i o n o f lo d e copper d e p o s i t s i n the Kluane Ranges: (a) n i c k e l - c o p p e r s u l f i d e s a s s o c i a t e d w i t h u l t r a m a f i c r o c k s . Stage 1 r e p r e s e n t s i n i t i a l emplacement o f u l t r a m a f i c magma. Stage 2 i s l a t e r a l f l o w o f the u l t r a m a f i c l i q u i d . Arrows i n d i c a t e s u l f u r con-t a m i n a t i o n o f magma from w a l l r o c k p r o b a b l y d u r i n g Stage 1 and p o s s i b l y d u r i n g Stage 2 ; ( b ) s u l f i d e s i n S t a t i o n Creek v o l c a n i c r o c k s . Arrows show p o s t u l a t e d l o c a l movement o f s u l f u r from d i s s e m i n a t e d and l e n t i c u l a r s u l f i d e s i n t o n o n - t h r o u g h g o i n g v e i n l e t s d u r i n g r e g i o n a l metamorphism; and (c) s u l f i d e s i n b a s a l t i c flows o f N i k o l a i G r e e n s t o n e. Throughgoing f r a c t u r e s c u t N i k o l a i Greenstone and t a p s u l f u r - b e a r i n g f l u i d s from both the Greenstone and u n d e r l y i n g Hasen Creek Formation d u r i n g r e g i o n a l metamorphism. Arrows i n d i c a t e f l o w o f s u l f u r - b e a r i n g f l u i d s . 132 the i n t r u s i o n c o u l d have p r o v i d e d a l l t h e s u l f u r n e c e s s a r y . Both mechanisms r e q u i r e t r a n s p o r t i n t o the magma v i a a f l u i d phase, perhaps connate water. The importance o f p y r i t e - b e a r i n g a r g i l l a c e o u s r o c k s w i t h i n the zone o f s i l l i n t r u s i o n , i s o b v i o u s . S i g n i f i c a n t c o ntaminant s u l f u r ( i n t h e o r d e r o f 30 t o 60 p e r c e n t o f t o t a l s u l f u r i n the d e p o s i t s ) from p y r i t i c w a l l r o c k s may have been c r u c i a l i n a c h i e v i n g s u l f u r s a t u r a t i o n o f the magma, l e a d i n g t o f o r m a t i o n o f t h e n i c k e l - c o p p e r d e p o s i t s . From an e x p l o r a t i o n p o i n t o f view t h i s v e r i f i c a t i o n o f t h e s u l f u r c o n t a m i n a t i o n model f o r development o f magmatic s u l f i d e b o d i e s has im p o r t a n t i m p l i c a t i o n s . S u l f u r s a t u r a t i o n may not have been o b t a i n e d u n t i l much l a t e r d u r i n g d i f f e r e n t i a t i o n o f the Kluane g a b b r o - u l t r a m a f i c complexes, u n l e s s s u l f u r c o n t a m i n a t i o n c o n t r i b u t e d towards s u l f u r s a t u r a t i o n o f t h e magma. In f a c t , i t i s p o s s i b l e t h a t w i t h o u t s u l f u r c o n t a m i n a t i o n no magmatic d e p o s i t s o f s u b s t a n c e would have e v o l v e d . C o n s e q u e n t l y , an i m p o r t a n t parameter i n q u a l i t a t i v e e v a l u a t i o n o f the n i c k e l - c o p p e r ore p o t e n t i a l o f any u l t r a m a f i c o r g a b b r o i c i n t r u s i o n might w e l l be t h e s u l f i d e c o n t e n t o f i n t r u d e d r o c k s and t h e presence o f ma r g i n a l s u l f u r -d e p l e t i o n h a l o e s where o r i g i n a l c o n t a c t s w i t h w a l l r o c k s are p r e s e r v e d . I s o t o p i c d a t a show a c o n t r a s t between s u l f i d e s i n Lower Permian S t a t i o n Creek Formation and those i n Upper T r i a s s i c N i k o l a i Greenstone. I s o t o p i c v a l u e s f o r both s y n g e n e t i c and v e i n s u l f i d e s i n S t a t i o n Creek t u f f s and flows d e f i n e narrow, p o s i t i v e , a l m o s t c o i n c i d e n t r a n g e s . R e g i o n a l metamorphism to lowermost g r e e n s c h i s t f a c i e s d i d not produce w h o l e s a l e h o m o g e n i z a t i o n . In f a c t , t h e o c c u r r e n c e o f comparable ranges o f s u l f u r i s o t o p i c c o m p o s i t i o n s f o r " m o b i l i z e d " v e i n s u l f i d e s and s y n g e n e t i c s u l f i d e s s u g g e s t s t h a t v e i n m i n e r a l i z a t i o n i s the r e s u l t 133 o f o n l y l o c a l m o b i l i z a t i o n o f s u l f u r (and m e t a l s ) d u r i n g metamorphism i n a c l o s e d system. S u l f i d e s i n the N i k o l a i Greenstone show a l a r g e range i n s u l f u r i s o t o p i c c o m p o s i t i o n . Coupled w i t h f i e l d and m i n e r a l o g r a p h i c d a t a , the i s o t o p i c v a l u e s can be shown to i n d i c a t e c o n s i d e r a b l e v a r i a t i o n i n c h e m i c a l parameters ( i n p a r t i c u l a r , ) o f t h e o r e - f o r m i n g f l u i d s . Thus, t h i s m i n e r a l i z i n g p r o c e s s appears to have o c c u r r e d i n an open system w i t h more than one s o u r c e o f s u l f u r needed t o account f o r t h e wide range i n i s o t o p i c d a t a . Two p o s s i b l e s o u r c e s o f s u l f u r i n c l u d e connate T r i a s s i c seawater i n lowermost N i k o l a i flows and connate Permian seawater i n u n d e r l y i n g Hasen Creek F o r m a t i o n . In t h e n i c k e l - c o p p e r d e p o s i t s the n i c k e l , c o p p e r , and p l a t i n u m group metals were p r e s e n t i n the o r i g i n a l magma as was about h a l f t h e s u l f u r . The r e m a i n i n g 30 t o 60 p e r c e n t o f s u l f u r was c o n t r i b u t e d from w a l l r o c k s . For the P i c k h a n d l e copper d e p o s i t i n S t a t i o n Creek Formation t h e c l o s e d system g e n e s i s r e q u i r e s t h a t c o p p e r , i r o n , and s u l f u r be d e r i v e d from the S t a t i o n Creek v o l c a n i c r o c k s . S u l f u r has been shown to be l a r g e l y i n t r o d u c e d i n t o copper s u l f i d e d e p o s i t s i n the N i k o l a i G r e e n s t o n e , but the copper p r o b a b l y was d e r i v e d from the Greenstone i t s e l f . T h i s work has combined e x t e n s i v e f i e l d and t r a d i t i o n a l l a b o r a t o r y s t u d i e s o f the p r i n c i p a l m i n e r a l d e p o s i t s c o n s i d e r e d w i t h s u l f u r i s o t o p e - o r i e n t e d m e t a l ! o g e n e t i c i n v e s t i g a t i o n s . Such an i n t e g r a t e d approach p r o v i d e s c l o s e c o n t r o l f o r sample s e l e c t i o n and a sound base f o r g e o l o g i c a l i n t e r p r e t a t i o n s o f the r e s u l t s . 134 ACKNOWLEGEMENTS F i n a n c i a l s u p p o r t f o r t h i s s t u d y was o b t a i n e d m a i n l y from t h e N a t i o n a l Research C o u n c i l o f Canada through an N.R.C. P o s t g r a d u a t e S c h o l a r s h i p t o S.W. Campbell and o p e r a t i n g g r a n t s t o Dr. A . J . S i n c l a i r . L a t e r c o n t r i b u t i o n s , t o a i d i n c o m p l e t i o n o f s p e c i f i c a s p e c t s o f the s t u d y , came from the N a t i o n a l S c i e n c e and E n g i n e e r i n g Research C o u n c i l , t h e A r c t i c and A l p i n e I n s t i t i t e o f The U n i v e r s i t y o f B r i t i s h Columbia, Western Mines L t d . , Vancouver, and Orequest E x p l o r a t i o n L t d . , Vancouver. F i e l d s u p p o r t i n c l u d i n g h e l i c o p t e r time was p r o v i d e d by the G e o l o g i c a l S u r v e y o f Canada, Department o f I n d i a n and N o r t h e r n A f f a i r s , and Western Mines L t d . Many o f t h e s u l f u r i s o t o p e a n a l y s e s were e i t h e r p r o v i d e d o r p a i d f o r by t h e G e o l o g i c a l Survey o f Canada. Numerous i n d i v i d u a l s have c o n t r i b u t e d t o the s u c c e s s o f t h i s work, i n c l u d i n g D r s . R.B. Campbell, J.W.H. Monger, P.B. Read, D.B. C r a i g , C.I. Godwin, A.E. S o r e g a r o l i , and C.A. A i r d , J.S. V i n c e n t , A . L . J . MacDonald, P. V e r s l u c e , W.B. Green, and G.E. Montgomery. N.W. S t a c e y a i d e d i n p r e p a r a t i o n o f some o f t h e samples f o r a n a l y s i s . M. M u e h l e r t and H. P i l t z a s s i s t e d i n t h e f i e l d work,, C r i t i c a l comments by D r s . A . J . S i n c l a i r , O.R. E c k s t r a n d , C.I. Godwin, and K.C. McTaggart have m a t e r i a l l y improved t h e p r e s e n t a t i o n . 135 REFERENCES Barnes, H.L., 1979, S o l u b i l i t i e s o f o re m i n e r a l s , i_n B a r n e s , H.L., ed . , G e o c h e m i s t r y o f hydrothermal ore d e p o s i t s , 2nd Ed.: New York, John W i l e y and Sons, p. 401-460. C a i r n e s , D.D., 1915, Upper White R i v e r d i s t r i c t , Yukon: Canada G e o l . Survey Mem. 50. Campbell, F.A., 1960, N i c k e l d e p o s i t s i n the Q u i l l Creek and White R i v e r a r e a s , Yukon: Canadian I n s t . M i n i n g M e t a l l u r g y T r a n s . , V. 63, p. 662-668. Campb e l l , R.B., and Dodds, C.J., 1978, O p e r a t i o n S a i n t E l i a s , Yukon T e r r i t o r y : Canada G e o l . Survey Paper 78-1A, p. 35-41. Campbell, R.B., and Dodds, C .J., 1979, O p e r a t i o n S a i n t E l i a s , B r i t i s h Columbia: Canada G e o l . Survey Paper 79-1A, p. 17-20. Campbell, S.W., 1976, N i c k e l - c o p p e r s u l f i d e d e p o s i t s i n the Kluane Ranges, Yukon T e r r i t o r y : Dept. I n d i a n and Northern A f f a i r s Open F i l e Rept. EGS1976-10, 17p. Cheney, E.S., 1974, Examples o f t h e a p p l i c a t i o n o f s u l f u r i s o t o p e s t o economic g e o l o g y : American I n s t . M i n i n q E n g i n e e r i n q T r a n s . , V. 255, p. 31-38. C h r i s t o p h e r , P.A., White, W.H., and Harakal , J . E . , 1972, K-Ar d a t i n g o f t he "Cork" (Burwash Creek) Cu-Mo p r o s p e c t , Burwash Landing a r e a , Yukon T e r r i t o r y : Canadian J o u r . E a r t h S c i . , V. 9, p. 918-921. E c k s t r a n d , O.R., 1972, U l t r a m a f i c flows and n i c k e l d e p o s i t s i n the A b i t i b i o r o g e n i c b e l t : Canada G e o l . Survey Paper 72-1 A, p. 75-82. E i s b a c h e r , G.H., 1976, Sedime n t o l o g y o f the Dezadeash f l y s c h and i t s i m p l i c a t i o n s f o r s t r i k e - s l i p f a u l t i n g a l o n g the D e n a l i F a u l t , Yukon T e r r i t o r y and A l a s k a : Canadian J o u r . E a r t h S c i . , V. 13, p. 1495-1513. F i n d l a y , D.C., 1969, The m i n e r a l i n d u s t r y o f Yukon T e r r i t o r y and Southwestern D i s t r i c t o f Mackenzie, 1968: Canadian G e o l . Survey Paper 69-55. G o d l e v s k i i , M.N., and G r i n e n k o , L.N., 1963, Some d a t a on the i s o t o p i c c o m p o s i t i o n s o f s u l f u r i n the s u l f i d e s o f the N o r i l ' s k deposit:, Geokhimiya, No. 1, p. 35-41. Green, L.H., and Godwin, C . I . , 1963, The m i n e r a l i n d u s t r y o f Yukon T e r r i t o r y and Southwestern D i s t r i c t o f Mackenzie, 1962: Canada G e o l . Survey Paper 63-36, p. 24-25. 136 Kirkham, R.V., 1972, Environments o f f o r m a t i o n o f copper s u l f i d e -n a t i v e copper d e p o s i t s i n v o l c a n i c sequences: I n t e r n a t . G e o l . Cong., 2 4 t h , M o n t r e a l , A b s t r a c t s , V . l , p. 170. K o v a l e n k e r , V.A., Gladyshev, G.D., and N o s i k , L.P., 1975, I s o t o p i c c o m p o s i t i o n o f s u l f i d e s u l f u r from d e p o s i t s o f Talnakh o r e node i n r e l a t i o n t o t h e i r s e l e n i u m c o n t e n t : I n t e r n a t . Geology Rev., V. 17, p. 725-734. Mainwaring, P.R., and N a l d r e t t , A . J . , 1977, C o u n t r y - r o c k a s s i m i l a t i o n and t h e q e n e s i s o f Cu-Ni s u l f i d e s i n the Water Hen i n t r u s i o n , Duluth Complex, M i n n e s o t a : Econ. G e o l . , V.72, p. 1269-1284. Monger, J.W.H., and P r i c e , R.A., 1979, Geodynamic e v o l u t i o n o f the Canadian C o r d i l l e r a - p r o g r e s s and problems: Canadian J o u r n a l E a r t h S c i . , V. 16, p. 770-791. N a l d r e t t , A . J . , 1966, The r o l e o f s u l f u r i z a t i o n i n the g e n e s i s o f i r o n - n i c k e l s u l f i d e d e p o s i t s o f t h e P o r c u p i n e D i s t r i c t , O n t a r i o : Canadian I n s t . M i n i n g M e t a l l u r g y T r a n s . , V. 59, p. 147-155. N i e l s e n , H., 1979, S u l f u r i s o t o p e s , vn_ J a g e r , E., and H u z i k e r , J.C., ed., L e c t u r e s i n i s o t o p e g e o l o g y : H e i d e l b e r g , S p r i n g e r -V e r l a g , p. 283-312. Ohmoto, H., 1972, S y s t e m a t i c s o f s u l f u r and carbon i s o t o p e s i n hydro-thermal o r e d e p o s i t s : Econ. G e o l . , V. 67, p. 551-578. Ohmoto, H., and Rye, R.O., 1979, I s o t o p e s o f s u l f u r and c a r b o n , i n Barne s , H.L., ed., G e o c h e m i s t r y o f hydrothermal o r e d e p o s i t s , 2nd Ed: New York, John W i l e y and Sons, p. 509-567. Read, P.B., and Monger, J.W.H., 1976, P r e - C e n o z o i c v o l c a n i c assemblages o f t h e Kluane and A l s e k Ranges, southwestern Yukon T e r r i t o r y : Canada G e o l . Survey Open F i l e Report 381, 96p. Rob e r t s o n , J.M., 1975, Geology and m i n e r a l o g y o f some copper s u l f i d e d e p o s i t s near Mount Bohemia, Keweenaw County, M i c h i g a n : Econ. G e o l . , V. 70, p. 1202-1224. Robinson, B.W., and Ohmoto, H., 1973, M i n e r a l o g y , f l u i d i n c l u s i o n s , and s t a b l e i s o t o p e s o f t h e Echo Bay U-Ni-Ag-Cu d e p o s i t s , Northwest T e r r i t o r i e s , Canada: Econ. G e o l . , V. 68, p. 635-656. Shima, M., G r o s s , W.H., and Thode, H.G., 1963, S u l f u r i s o t o p e abundances i n b a s i c s i l l s , d i f f e r e n t i a t e d g r a n i t e s , and m e t e o r i t e s : J o u r . G e o p h y s i c a l R e s e a r c h , V. 68, p. 2835 - 2847. S i l b e r m a n , M.L., MacKevett, E.M., Conner, C.L., and Matthews, A., 1980 - M e t a l l o g e n i c and t e c t o n i c s i g n i f i c a n c e o f oxygen i s o t o p e da t a w i t h whole-rock potassium-argon ages o f the N i k o l a i Greenstone McCarthy Quadrangle, A s l a s k a : U.S. G e o l . Survey Open F i l e Report 80-2019, 29p. 137 S i n c l a i r , A . J . , 1977, The White R i v e r c o p p e r d e p o s i t , southwestern Yukon: Canada G e o l . A s s o c . Program, Annual M e e t i n g , Vancouver, A b s t r a c t s , p.49. S i n c l a i r , A . J . , Bentzen, A., and McLeod, J.A., 1979, Geology o f the White R i v e r n a t i v e copper d e p o s i t , Yukon T e r r i t o r y : Dept. I n d i a n and N o r t h e r n A f f a i r s , N o r t h e r n A f f a i r s Program, 27p. S i n c l a i r , W.D., and G i l b e r t , G.W., 1975, M i n e r a l I n d u s t r y r e p o r t , Yukon T e r r i t o r y , 1973: Dept. I n d i a n and N o r t h e r n A f f a i r s , EGS1975-7. S m i t h e r i n g a l e , W.G., and J e n s e n , M.L., 1963, S u l f u r i s o t o p i c c o m p o s i t i o n o f the T r i a s s i c igneous r o c k s o f e a s t e r n U n i t e d S t a t e s : Geochim. e t Cosmochim. A c t a , V.27, p. 1183-1207. S t a n t o n , R.L., 1972, Ore p e t r o l o g y : M c G r a w - H i l l , I n c . , p. 175-188. Thode, H.G., Dunford, H.B., and Shima, M., 1962, S u l f u r i s o t o p i c abundances i n r o c k s o f the Sudbury d i s t r i c t and t h e i r g e o l o g i c a l s i g n i f i c a n c e : Econ. Geo!., V.57, p. 565-578. Tupper, W.M., 1960, S u l f u r i s o t o p e s and the o r i g i n o f s u l f i d e d e p o s i t s o f the B a t h u r s t Newcastle a r e a o f n o r t h e r n New Brunswick: Econ. G e o l . , V.55, p. 1676-1707. V i n o g r a d o v , A.P., and G r i n e n k o , L.N., 1964, The e f f e c t o f e n c l o s i n g r o c k s on the i s o t o p i c c o m p o s i t i o n o f s u l f u r i n s u l f i d e o r e m i n e r a l s : Geokhimiya, No. 6, p. 491-499. 138 CHAPTER 5 SULPHUR CONTAMINATION MODEL FOR MAGMATIC NICKEL-COPPER DEPOSITS 139 ABSTRACT M i n e r a l o g y , s u l p h u r i s o t o p e d a t a , w a l l r o c k x e n o l i t h s , p y r r h o t i t e h a l o e s , and p o s s i b l e d e p l e t i o n h a l o e s combine t o g i v e s t r o n g e v i d e n c e f o r s u l p h u r c o n t a m i n a t i o n o f c e r t a i n g a b b r o i c to u l t r a m a f i c i n t r u s i o n s and t h e i r a s s o c i a t e d n i c k e l - c o p p e r s u l p h i d e d e p o s i t s . In p a r t i c u l a r , s u l p h u r i s o t o p i c c o m p o s i t i o n s o f many magmatic s u l p h i d e d e p o s i t s l i e between i s o t o p i c v a l u e s f o r w a l l r o c k s u l p h i d e s and z e r o p e r m i l T h i s i n d i c a t e s the s o u r c e o f t h e contaminant s u l p h u r t o be t h e w a l l -r o c k s o r r o c k s t r a v e r s e d d u r i n g a s c e n t o f t h e r e l a t e d p l u t o n i c d i a p i r . C o n t a m i n a t i o n o f m a f i c / u l t r a m a f i c magma a p p a r e n t l y i s n o t r e s t r i c t e d t o any p a r t i c u l a r s t a g e i n the development o f a g a b b r o i c to u l t r a m a f i c complex. R a t h e r , c o n t a m i n a t i o n may o c c u r d u r i n g any one o r more than one o f t h e f o l l o w i n g : d i a p i r i c r i s e ; i n i t i a l i n t r u s i o n ; p r o g r e s s i v e l a t e r a l f l o w o f t h e magma; c r y s t a l l i z a t i o n and/or f o r m a t i o n o f a l a y e r e d s e r i e s ; and d u r i n g i m m i s c i b l e s u l p h i d e i n j e c t i o n . The mechanism o f magma c o n t a m i n a t i o n may i n v o l v e f l u i d f l o w toward and i n t o an u n d e r s a t u r a t e d magma, a s s i m i l a t i o n o f w a l l r o c k m a t e r i a l o r a c o m b i n a t i o n o f th e s e p r o c e s s e s . The proposed g e n e t i c model l e a d s to c e r t a i n f i e l d c r i t e r i a t h a t a r e i m p o r t a n t i n e x p l o r a t i o n f o r n i c k e l - c o p p e r s u l p h i d e d e p o s i t s , namely, h i g h s u l f h u r c o n t e n t o f c o u n t r y rock and s u l p h u r d e p l e t i o n h a l o e s a d j a c e n t t o u l t r a m a f i c i n t r u s i o n s . HISTORICAL BACKGROUND R e c o g n i t i o n o f t h e a f f i n i t y o f n i c k e l - c o p p e r s u l p h i d e d e p o s i t s 140 f o r g a b b r o i c and u l t r a m a f i c r o c k s b e f o r e t h e t u r n o f t h e c e n t u r y l e d Vogt to conduct experiments showing t h e p l a u s i b i l i t y o f s u p p o s i n g t h a t t h e s e d e p o s i t s r e s u l t e d from i m m i s c i b i l i t y o f a s u l p h i d e l i q u i d i n t h e s i l i c a t e m e lt ( S t a n t o n , 1972). In t h e e a r l y t w e n t i e t h c e n t u r y and w i t h t h e work o f Vogt (1921) many n i c k e l - c o p p e r s u l p h i d e d e p o s i t s were thought to o r i g i n a t e by s e p a r a t i o n o f an i m m i s c i b l e s u l p h i d e l i q u i d w i t h i n t h e h o s t magma. T h i s g e n e r a l h y p o t h e s i s has p e r s i s t e d t o the p r e s e n t day ( N a l d r e t t , 1973; Usselman ejt a l _ . , 1979), a l t h o u g h t h e r e have been r e c e n t s u g g e s t i o n s o f o t h e r o r i g i n s f o r some o f the d e p o s i t s ( L u s k , 1976; F l e e t , 1977; F l e e t e t a l _ . , 1977). D e s p i t e some u n c e r t a i n t i e s r e g a r d i n g g e n e s i s i n s p e c i f i c c a s e s , t h e r e seems t o be overwhelming t e x t u r a l and e x p e r i m e n t a l e v i d e n c e t h a t an i m m i s c i b l e s u l p h i d e l i q u i d does form an i m p o r t a n t stage i n the e v o l u t i o n o f many n i c k e l - c o p p e r d e p o s i t s i n g a b b r o i c and u l t r a m a f i c r o c k s , and i t i s w i t h t h i s c a t e g o r y o f d e p o s i t t h a t we con c e r n our-s e l v e s h e r e . An i m p l i c i t assumption i n the t h e o r y o f s e p a r a t i o n o f an i m m i s c i b l e s u l p h i d e l i q u i d i s t h a t t he s o u r c e o f metals and s u l p h u r i s t h e p a r e n t magma, a l t h o u g h as i n d i c a t e d below s e v e r a l a u t h o r s have s p e c u l a t e d r e c e n t l y t h a t some s u l p h u r i s d e r i v e d from e x t r a n e o u s s o u r c e s . Many magmatic n i c k e l - c o p p e r d e p o s i t s have s u l p h u r i s o t o p i c c o m p o s i t i o n s near 0 p e r m i l (Shima e t a l _ . , 1963; S m i t h e r i n g a l e and J e n s e n , 1963; S t a n t o n , 1972; Ohmoto and Rye, 1979). However, some n i c k e l - c o p p e r s u l p h i d e o c c u r r e n c e s have s i g n i f i c a n t l y h e a v i e r o r l i g h t e r i s o t o p i c c o m p o s i t i o n s o f s u l p h u r . E x p l a n a t i o n s f o r t h e s e anomalous s u l p h u r i s o t o p e s i n c l u d e : (1) inhomogeneity i n mantle s u l p h u r ( S a s a k i , 1969); (2) s u l p h u r i z a t i o n ( N a l d r e t t , 1966; L i e b e n b e r g , 141 1970); and (3) w a l l r o c k c o n t a m i n a t i o n o f the magma (Mainwaring and N a l d r e t t , 1977; L i e b e n b e r g , 1970; G o d l e v s k i i and Gr i n e n k o , 1963; Chapter 4 ) . EVIDENCE FOR MAGMA CONTAMINATION G e o l o g i c a l f e a t u r e s and i s o t o p i c d a t a f o r many s u l p h i d e - b e a r i n g g a b b r o i c and u l t r a m a f i c i n t r u s i o n s a r e i n d i c a t i v e o f c o n t a m i n a t i o n o f the i n t r u d i n g magma by c o u n t r y r o c k , o r some component o f c o u n t r y r o c k , i n c l o s e p r o x i m i t y t o t h e i n t r u s i v e body. Mainwaring and N a l d r e t t (1977) p r o v i d e a d e t a i l e d account o f c o n t a m i n a t i o n o f the Water Hen i n t r u s i o n n e a r Duluth Complex by m a t e r i a l from t h e e n c l o s i n g V i r g i n i a s l a t e s . They c i t e c o r d i e r i t e - , b i o t i t e - , s p i n e l - , o r g r a p h i t e - b e a r i n g u l t r a m a f i t e s , i n t e r g r o w n g r a p h i t e and s u l p h i d e s , i n c l u s i o n s o f r e c r y s t a l l i z e d s l a t e composed o f c o r d i e r i t e , o r t h o p y r o x e n e , and s p i n e l w i t h i n the i n t r u s i o n , and p y r r h o t i t e r a t h e r than p y r i t e i n t h e r e c r y s t a l l i z e d w a l l r o c k s , as e v i d e n c e o f w a l l r o c k a s s i m i l a t i o n and quote l i m i t e d s u l p h u r i s o t o p i c a n a l y s e s i n d i c a t i n g t h a t as much as 75 p e r c e n t o f t h e s u l p h u r c o n t a i n e d i n "magmatic" s u l p h i d e s may have o r i g i n a t e d from t h e w a l l r o c k . S i m i l a r l y , a d e t a i l e d documentation o f s u l p h u r i s o t o p e c o n t a m i n a t i o n o f two Lower T r i a s s i c u l t r a m a f i c complexes i n so u t h w e s t e r n Yukon T e r r i t o r y i s p r o v i d e d i n Chapter 4. The argument i s f u r t h e r s t r e n g t h e n e d by t h e i n d i c a t i o n o f i n f l u x o f v o l a t i l e s t o t h e magma to form l i q u i d u s h o r n b l e n d e and b i o t i t e , by h o r n f e l s e d w a l l r o c k x e n o l i t h s o f c l i n o p y r o -xene and p l a g i o c l a s e w i t h i n b a s a l p a r t s o f t h e Q u i l l Creek p e r i d o t i t i c s i l l , and by a p o s s i b l e s u l p h i d e d e p l e t i o n h a l o i n w a l l r o c k a l o n g the bo r d e r s o f t h e Kluane complexes. Contaminant s u l p h u r can be shown to 142 have been i n t r o d u c e d a t more than one time d u r i n g e v o l u t i o n o f t h e v a r i o u s o r e s and f r a c t i o n a l c r y s t a l l i z a t i o n o f the p a r e n t magma. Mass b a l a n c e c a l c u l a t i o n s based on t o t a l s u l p h u r c o n t e n t i n d i c a t e t h a t t he c o n t a m i n a t i n g s u l p h u r c o u l d have been d e r i v e d from r e l a t i v e l y s m a l l volumes o f p y r i t i c h o s t r o c k , r e p r e s e n t e d a t l e a s t c o n c e p t u a l l y by e x t r a c t i o n from a narrow c o n t a c t zone (5 t o 10 m wide) around t he r e l a t e d u l t r a m a f i c s i l l s . O ther s u l p h i d e - b e a r i n g g a b b r o i c and u l t r a m a f i c r o c k s show e v i d e n c e o f magma c o n t a m i n a t i o n . Minor g r a p h i t e i s a s s o c i a t e d w i t h d i s s e m i n a t e d t o massive s u l p h i d e s and t h e h o s t n o r i t e and p e r i d o t i t e i n the Rana i n t r u s i o n , Norway (Boyd> and M a t h i e s o n , 1979). Some o f the F i n n i s h u l t r a m a f i t e s c o n t a i n l o c a l g r a p h i t e , p l a g i o c l a s e , and hydrous s i l i c a t e m i n e r a l s , s u g g e s t i v e o f w a l l r o c k c o n t a m i n a t i o n (Papunen e t a l . , 1979). A h y b r i d zone o f g a r n e t - h o r n b l e n d e - r i c h r o c k s o c c u r s between p e n e t r a t i v e tongues o f mica g n e i s s c o u n t r y rock and the Vammala complex, F i n l a n d ( H a k l i et_ a l _ . , 1979). The main Phase o f t h e B u s h v e l d complex c o n t a i n s x e n o l i t h s o f q u a r t z i t e and h o r n f e l s near i t s margin and base and a p y r r h o t i t e h a l o appears i n P r e t o r i a S e r i e s s e d i m e n t a r y w a l l r o c k s . I n c l u s i o n s o f c o a l c o n v e r t e d to g r a p h i t e are found i n the N o r i l ' s k s i l l s ( G o d l e v s k i i and G r i n e n k o , 1963). I r v i n e (1970) i n t e r p r e t s t h e d i s c o n t i n u o u s granophyre u n i t a l o n g t h e r o o f c o n t a c t o f t h e Muskox i n t r u s i o n as h a v i n g formed from melted r o o f r o c k s . C a l -c u l a t i o n s by him show t h a t w i t h i n the time r e q u i r e d f o r a c c u m u l a t i o n o f t h e Muskox l a y e r e d s e r i e s more than enough s a l i c r o o f rock t h e o r e -t i c a l l y c o u l d have been m e l t e d t o a c c o u n t f o r the obs e r v e d amount o f g ranophyre. S i m i l a r l y , c o n t a m i n a t i o n by r o o f r o c k s t o produce upper g r a n o p h y r i c p a r t s o f l a y e r e d complexes has been proposed f o r 143 the S k a e r g a a r d and B u s h v e l d (Wager and Brown, 1968). G a b b r o i c t o u l t r a m a f i c complexes are g e n e r a l l y thought t o be m a n t l e - d e r i v e d and, as s u c h , t h e i r c o n t a i n e d s u l p h u r s h o u l d have an i s o t o p i c c o m p o s i t i o n e q u i v a l e n t t o t h a t o f p r i m o r d i a l s u l p h u r . Indeed, numerous s u l p h u r i s o t o p i c c o m p o s i t i o n s o f p r i m a r y s u l p h i d e m i n e r a l s i n g a b b r o i c and u l t r a m a f i c r o c k s do c l u s t e r around 0 p e r m i l ( F i g u r e 1) and, i n g e n e r a l , f a l l i n the range -1 t o +2 p e r m i l P 4 S (Shima e t a l _ . , 1963; S m i t h e r i n g a l e and Jensen, 1963; S t a n t o n , 1972; Ohmoto and Rye, 1979; N i e l s e n , 1979). However, some magmatic n i c k e l -c o pper d e p o s i t s have s i g n i f i c a n t l y h e a v i e r or l i g h t e r i s o t o p i c c o m p o s i t i o n s o f s u l p h u r . These "anomalous" v a l u e s s u g g e s t t h a t p a r t o r a l l o f the s u l p h u r has been d e r i v e d from a s o u r c e o t h e r than the upper mantle. S e v e r a l a u t h o r s have s u g g e s t e d t h a t c o n t a m i n a t i o n o f the magma has caused t h i s s h i f t from 0 p e r m i l ( G o d l e v s k i i and G r i n e n k o , 1963; N a l d r e t t , 1966; L i e b e n b e r g , 1970; Mainwaring and N a l d r e t t , 1977; C h a p t e r 4 ) . S o u r c e s o f t h i s c o n t a m i n a t i o n i n c l u d e b o t h r o c k s i n t r u d e d d u r i n g a s c e n t o f t h e magma and t h e w a l l r o c k s . In a d d i t i o n t o such m i n e r a l o g i c a l and s u l p h u r i s o t o p i c e v i d e n c e a s u b s t a n t i a l l i t e r a t u r e e x i s t s to i n d i c a t e t h a t many u l t r a m a f i c magmas have been c o n t a m i n a t e d a t some s t a g e i n t h e i r c r y s t a l l i z a t i o n h i s t o r y . The l o n g s t a n d i n g i n t e r p r e t a t i o n t h a t s c y e l i t e s r e p r e s e n t u l t r a m a f i c magmas c o n t a m i n a t e d by c r u s t a l d e r i v e d f l u i d s and o t h e r components i s one such example ( H a r k e r , 1954). I s o t o p i c e v i d e n c e o t h e r than s u l p h u r p r o v i d e s i n d i c a t i o n s o f c o n t a m i n a t i o n . Much o f t h e work w i t h t h e oxygen i s o t o p e s o f u l t r a -m a f i c r o c k s has been d i r e c t e d a t d e t e r m i n i n g the s o u r c e o f water l e a d i n g t o s e r p e n t i n i z a t i o n and toward d e t e r m i n i n g temperatures i n v o l v e d 144 - 20 - 10 0 10 20 ARCH CREEK ILL CREES SUDBURY PORCUPINE AREA NIPISSING DIABASE COBALT SILL LEITCH SILL STILLWATER PAL ISADES SILL P U R C E L L G A B B R O PERIDOTITES, MAINE <SULFIDE G A B B R O DIABASE, E A S T US. MAFICS, ULTRAMAFICS G A B B R O S , PERIDOTITES « U m i J ml fi 11 fl in if I II iii Hi ti 20 —10 0 10 20 S 3 4 s^o F i g u r e 1. S u l p h u r i s o t o p i c data f o r W e l l g r e e n , Arch Creek, and Canalask n i c k e l - c o p p e r d e p o s i t s and f o r a s e l e c t i o n o f o t h e r g a b b r o i c and u l t r a -m a f i c i n t r u s i o n s . Data are from: Thode e t aj_. (1962); N a l d r e t t (1966); S t a n t o n (1972); Shima e t aj_. (1963); S m i t h e r i n g a l e and Jensen (1963). 145 I D ( M a g a r i t z and T a y l o r , 1974; Wenner and T a y l o r , 1973). Low 0 r e s u l t s f o r S c o t t i s h gabbros, b a s a l t s , and g r a n i t e s were i n t e r p r e t e d by T a y l o r and F o r e s t e r (1971) as b e i n g the r e s u l t o f c o n t a m i n a t i o n by l a r g e c o n v e c t i o n systems composed o f heated m e t e o r i c ground waters w i t h low 18 0 v a l u e s . U n u s u a l l y h i g h oxygen i s o t o p i c c o m p o s i t i o n s and h i g h 87 86 S r / S r r a t i o s f o r r o c k s i n t h e Tuscan magmatic p r o v i n c e o f I t a l y 18 were used t o argue f o r l a r g e s c a l e a s s i m i l a t i o n o f h i g h rj a r g i l l a c e o u s s e d i m e n t a r y c o u n t r y r o c k s ( T a y l o r and T u r i , 1976). A r e l a t i v e l y 87 86 h i g h S r / S r r a t i o o f 0.706 f o r the Sudbury n o r i t e i s used t o s u p p o r t t h e i d e a o f p o s s i b l e c o n t a m i n a t i o n o f t h e magma by q u a r t z -r i c h m a t e r i a l ( N a l d r e t t and MacdonaTd, 1981). Faure e t aj_. (1974) 87 8fi e x p l a i n e d t h e i n c r e a s i n g S r / S r r a t i o s o f J u r a s s i c b a s a l t s i n Queen A l e x a n d r a Range by means o f v a r y i n g a d d i t i o n s o f a contaminant, d e r i v e d from t h e g r a n i t i c basement, t o a b a s a l t magma t h a t o r i g i n a t e d 87 86 i n t h e upper m a n t l e . The r e l a t i v e l y h i g h i n i t i a l S r / S r i s o t o p e r a t i o o f g a b b r o - d i o r i t e i n the P y r o x e n i t e Creek u l t r a m a f i c complex, Yukon T e r r i t o r y , i s i n t e r p r e t e d by S t u r r o c k e_t al_. (1980) to i n d i c a t e c o n t a m i n a t i o n w i t h c r u s t a l m a t e r i a l and perhaps h y b r i d i z a t i o n o f p y r o x e n i t e magma w i t h w a l l r o c k s i n c r u s t a l magma chambers below the p r e s e n t l e v e l o f e x p o s u r e . EVIDENCE FOR SOURCE OF SULPHUR Some o f the e v i d e n c e f o r c o n t a m i n a t i o n o f m a f i c and u l t r a m a f i c magmas i s c i r c u m s t a n t i a l o r ambiguous, but many o f t h e d a t a , p a r t i c u l -a r l y p e t r o g r a p h i c and s u l p h u r i s o t o p e d a t a , appear u n e q u i v o c a l i n r e q u i r i n g t h a t c o n t a m i n a t i o n o f u l t r a m a f i c magmas has o c c u r r e d . The 146 s u l p h u r i s o t o p i c d a t a a r e o f p a r t i c u l a r c o n c e r n h e r e , but the o t h e r i n d i c a t i o n s o f c o n t a m i n a t i o n are i m p o r t a n t i n e s t a b l i s h i n g a compre-h e n s i v e p i c t u r e o f what can be i n v o l v e d i n the c o n t a m i n a t i o n p r o c e s s . I t appears t h a t t h e s e examples and o t h e r s o f the same i l k e s t a b l i s h c o n t a m i n a t i o n o f m a n t l e - d e r i v e d u l t r a m a f i c magmas by c r u s t a l components as a g e n e r a l p r o c e s s . G a b b r o i c and u l t r a m a f i c i n t r u s i o n s t h a t show e i t h e r no e v i d e n c e o f w a l l r o c k c o n t a m i n a t i o n o r c o n t a m i n a t i o n by w a l l r o c k f r e e o f s u l p h i d e s ( o r s u l p h a t e ) have n i c k e l - c o p p e r d e p o s i t s w i t h s u l p h u r i s o t o p i c compos-i t i o n s near 0 p e r m i l o S. T h i s s u p p o r t s the s u g g e s t i o n o f a homogeneous s u l p h u r i s o t o p i c c o m p o s i t i o n i n the upper mantle (Ohmoto and Rye, 1979; Shima e t a l _ . , 1963). Some i d e a o f t h e g e n e r a l i t y o f s u l p h u r c o n t a m i n a t i o n can be o b t a i n e d by examining i s o t o p i c d a t a f o r s u l p h i d e s i n g a b b r o i c and u l t r a m a f i c complexes and a s s o c i a t e d w a l l r o c k s f o r a v a r i e t y o f examples i n which i s o t o p i c c o m p o s i t i o n s f o r t h e two rock groups d i f f e r . Data f o r a number o f such examples, e x t r a c t e d from the l i t e r a t u r e as w e l l as from the w r i t e r ' s r e s e a r c h , a r e i l l u s t r a t e d i n F i g u r e 2. The arrangement o f examples documented i n F i g u r e 2 i s such as t o emphasize a s t a r t l i n g r e l a t i o n s h i p . Where s u l p h u r i s o t o p i c c o m p o s i t i o n s o f t h e n i c k e l - c o p p e r s u l p h i d e s d i f f e r from both z e r o p e r m i l and the c o m p o s i t i o n o f s u l p h u r i n a d j o i n i n g w a l l r o c k , the n i c k e l - c o p p e r s u l p h i d e i s o t o p i c c o m p o s i t i o n s i n v a r i a b l y l i e between 0 p e r m i l and i s o t o p i c v a l u e s f o r t h e w a l l r o c k . Such a p a t t e r n might a r i s e due t o chance i n a few c a s e s , but when the p a t t e r n i s as c o n s i s t e n t as demonstrated h e r e , the n e c e s s a r y c o n c l u s i o n i s t h a t t h e s u l p h i d e - s u l p h u r i s o t o p i c c o m p o s i t i o n s a r i s e as a m i x t u r e o f magmatic s u l p h u r and w a l l r o c k s u l p h u r . A c c o r d i n g t o t h i s h y p o t h e s i s a l i n e a r m i x i n g model i s i m p l i e d and average i s o t o p i c r a t i o s can be 147 20 40 WATER HEN, MINN. ***** o I NORIL'SK, USSR MUSKOX, NWT ALEXO, ONT. VAMMALA, FINLAND HITURA + KOTALAHTI, FINLAND . [ MARGINAL ZONE LAYERED SERIES ao UPPER LAYER HORNBLENDITE LOWER LAYER KAMBALDA, W. AUSTRALIA WINDARRA, W. AUSTRALIA KYLMAKOSKI, FINLAND J RANA, NORWAY BUSHVELD, S. AFRICA W1 C - 4 0 KLUANE, YUKON - 2 0 0 S 3 4 e < / V>/>0 20 40 F i g u r e 2. C o m p i l a t i o n o f s u l p h u r i s o t o p i c d a t a f o r n i c k e l - c o p p e r s u l -p h i d e s a s s o c i a t e d w i t h g a b b r o i c o r u l t r a m a f i c r o c k s , which show e v i d e n c e o f c o n t a m i n a t i o n , and f o r s u l p h i d e s i n w a l l r o c k s o r i n t r u d e d c o u n t r y r o c k s . Data a r e from Papunen e t al_. (1979); Boyd and Mathieson (1979); N a l d r e t t (1966); Groves e t al_.~Cl979); L i e b e n b e r g (1970); Mainwaring and N a l d r e t t (1977); S a s a k i TT969); G o d l e v s k i i and Grinenko (1963); H a k l i e t al_. (1979); and from C h a p t e r 4. 148 used t o o b t a i n an e s t i m a t e o f t h e p r o p o r t i o n o f s u l p h u r c o n t r i b u t e d from w a l l r o c k t o form n i c k e l - c o p p e r d e p o s i t s o f magmatic o r i g i n . F i g u r e 2 i l l u s t r a t e s s u b s t a n t i a l v a r i a b i l i t y i n p r o p o r t i o n o f contaminant and magmatic s u l p h u r and s i m p l e c a l c u l a t i o n s i n d i c a t e as much as 75 p e r c e n t w a l l r o c k s u l p h u r i n d e p o s i t s o f t h e Water Hen i n t r u s i o n (Mainwaring and N a l d r e t t , 1977), perhaps 70 p e r c e n t w a l l r o c k s u l p h u r i n t h e case o f s u l p h i d e s i n t h e B u s h v e l d m a r g i n a l zone ( L i e b e n b e r g , 1970), and from 30 t o 60 p e r c e n t w a l l r o c k s u l p h u r i n the ca s e o f t h e W e l l g r e e n and Canalask n i c k e l - c o p p e r d e p o s i t s , r e s p e c t i v e l y ( C h a p t e r 4 ) . Of c o u r s e c o n t a m i n a t i o n w i l l n o t always be obvious through s u l p h u r i s o t o p i c " t r a c e r s . " F o r example, g a b b r o i c and u l t r a m a f i c r o c k s may be emplaced i n a v o l c a n i c sequence c h a r a c t e r i z e d by near 0 p e r m i l s u l p h u r , i n which case c o n t a m i n a t i o n c o u l d not be m o n i t o r e d because t h e two components have e s s e n t i a l l y i d e n t i c a l c o m p o s i t i o n s . T h i s may be t h e s i t u a t i o n w i t h many Precambrian k o m a t i i t e s . TIMING OF CONTAMINATION I t seems p o s s i b l e t h a t s e v e r a l s t a g e s o f s u l p h u r c o n t a m i n a t i o n c o u l d o c c u r t h r o u g h o u t t he c o n s o l i d a t e d h i s t o r y o f a s i n g l e u l t r a m a f i t e and i t s a s s o c i a t e d magmatic s u l p h i d e s . S u l p h i d e s e g r e g a t i o n b e g i n s a t t h e time o f s u l p h u r s a t u r a t i o n and i n an i d e a l i z e d s i t u a t i o n would c o n t i n u e d u r i n g d i f f e r e n t i a t i o n . C o n t a m i n a t i o n by w a l l r o c k s u l p h u r c o u l d o c c u r a t any time d u r i n g t h i s l o n g h i s t o r y . For example, G o d l e v s k i i and Grinenko (1963) s u g g e s t t h a t the N o r i l ' s k magmas a c q u i r e d e v a p o r i t e s u l p h a t e d u r i n g t h e i r a s c e n t and t h a t p o s s i b l e i n c o r p o r a t i o n o f c a r b o n from c o a l beds a t h i g h e r s t r a t i g r a p h i c l e v e l s may have reduced 149 t h e s u l p h a t e t o s u l p h i d e d i r e c t l y a t temperatures g r e a t e r than 600 C. In c o n t r a s t to t h i s , Vammala complex shows c o n t a m i n a t i o n o n l y i n the l a s t magmatic phase, t h e upper u l t r a m a f i c l a y e r , where t h e r e i s a s h i f t i n average i s o t o p i c v a l u e by +11 pe r m i l Another example, s u l p h u r c o n t a m i n a t i o n i n the Rana m a f i c i n t r u s i o n , i s a l o c a l i z e d f e a t u r e s u g g e s t i n g t h a t much o f t h e s i l i c a t e and s u l p h i d e had a l r e a d y s e p a r a t e d and c r y s t a l l i z e d . In t h i s case o f s u l p h u r c o n t a m i n a t i o n a t such a l a t e s t a g e , i n h o m o g e n e i t i e s i n s u l p h u r c o m p o s i t i o n o f w a l l r o c k , combined w i t h o n l y l o c a l h o m o g e n i z a t i o n i n the magma, may ac c o u n t f o r t h e l a r g e range i n i s o t o p i c v a l u e s o f s u l p h i d e s a s s o c i a t e d w i t h g r a p h i t e . Thus, c o n t a m i n a t i o n p r i o r t o suphi d e i m m i s c i b i l i t y might l e a d t o homogeneous m i x i n g o f magmatic and contaminant s u l p h u r and r e l a t i v e u n i f o r m i t y o f s u l p h u r i s o t o p e s t h r o u g h o u t the magma chamber, whereas c o n t a m i n a t i o n a f t e r s u l p h u r s a t u r a t i o n would have t h e p o t e n t i a l o f p r o d u c i n g a g r e a t e r v a r i a b i l i t y i n s u l p h u r i s o t o p i c c o m p o s i t i o n s . C o n t a m i n a t i o n i n t h i s l a t t e r case would depend c r i t i c a l l y on s u l p h u r d i f f u s i o n i n the s u l p h i d e w h i l e l i q u i d i s s t i l l p r e s e n t and may o n l y work a f t e r c o n v e c t i o n has c e a s e d . S u c c e s s i v e s t a g e s o f c o n t a m i n a t i o n s h o u l d be t r a c e a b l e because o f s y s t e m a t i c v a r i a t i o n s i n s u l p h u r i s o t o p i c c o m p o s i t i o n s w i t h s t a g e o f d i f f e r e n t i a t i o n . An ap p a r e n t bimodal d i s t r i b u t i o n o f s u l p h u r i s o t o p i c r a t i o s ( o f -3.5 and -6.0 p e r m i l ) f o r n i c k e l - c o p p e r d e p o s i t s a s s o c i a t e d w i t h t he Q u i l l Creek complex may be an example o f t h i s phenomenon ( C h a p t e r 4 ) . A l s o , i s o t o p i c d a t a f o r n i c k e l - c o p p e r s u l p h i d e s i n t h e White R i v e r p e r i d o t i t e a t Canalask (-14.4 p e r m i l ) and i n nearby s u l p h i d e i n j e c t i o n b o d i e s (-18.5 p e r m i l ) appear t o i n d i c a t e two s t a g e s o f c o n t a m i n a t i o n by w a l l r o c k s u l p h u r . 150 The p o s s i b i l i t y e x i s t s t h a t t i m i n g o f c o n t a m i n a t i o n may be r e -s t r i c t e d by che m i c a l changes i n the l i q u i d d u r i n g d i f f e r e n t i a t i o n . F l e e t ejt al_. (1981), f o r example, p r e s e n t c o n v i n c i n g arguments t h a t the p a r t i t i o n i n g o f n i c k e l i n t o a s u l p h i d e magma d e c r e a s e s as d i f f e r e n t i a t i o n p r o c e e d s : t h a t i s , a s MgO c o n t e n t o f the s i l i c a t e magma de c r e a s e s o r FeO c o n t e n t o f t h e magma i n c r e a s e s . I f t r u e , contamin-a t i o n must take p l a c e r e l a t i v e l y e a r l y i n the d i f f e r e n t i a t i o n h i s t o r y o f t h e u l t r a m a f i c magma. T h i s t i m i n g i s c e r t a i n l y c o n s i s t e n t w i t h a s u g g e s t i o n t h a t r e l a t i v e l y s h o r t - l i v e d h i g h temperature c o n t a c t zones may p r o v i d e t he contaminant s u l p h u r (see C h a p t e r 4 ) . SULPHUR CONTAMINATION PROCESS The f o r g o i n g arguments have been d i r e c t e d towards e s t a b l i s h i n g the g e n e r a l i t y o f c o n t a m i n a t i o n o f m a f i c and u l t r a m a f i c magmas, p a r t i c u l a r l y i n r e g a r d t o s u l p h u r , and t o d e l i n e a t i n g p o s s i b l e s t a g e s o f such con-t a m i n a t i o n . The p r o c e s s e s by which magma c o n t a m i n a t i o n can o c c u r must now be c o n s i d e r e d . P o s s i b l e p r o c e s s e s i n c l u d e : (1) bu l k a s s i m i l a t i o n o f s u l p h u r - c o n t a i n i n g w a l l r o c k ; (2) i n c o n g r u e n t m e l t i n g o f p y r i t e i n the c o n t a c t a u r e o l e t o produce p y r r h o t i t e p l u s s u l p h u r ; and (3) complete breakdown o f p y r i t e o r o t h e r s u l p h u r - b e a r i n g m i n e r a l s i n the c o n t a c t a u r e o l e . Bulk A s s i m i l a t i o n T h i s p r o c e s s i n v o l v e s t h e c o n t r i b u t i o n o f l a r g e q u a n t i t i e s o f rock m a t e r i a l (the volume b e i n g dependent on the o v e r a l l abundance o f c o n t a i n e d s u l p h u r ) . As shown p r e v i o u s l y the p r o p o r t i o n o f the two s u l p h u r compon-ents (magmatic and w a l l r o c k ) can be c a l c u l a t e d e a s i l y . I f average s u l p h u r 151 c o n t e n t s o f magma and w a l l r o c k can be e s t a b l i s h e d rough mass b a l a n c e c a l c u l a t i o n s can be at t e m p t e d . Data a r e n o t a v a i l a b l e f o r most p u b l i s h e d examples, but th e s e c a l c u l a t i o n s have been attempted f o r the Q u i l l Creek and White R i v e r u l t r a m a f i c s i l l s i n southwestern Yukon T e r r i t o r y . Q u a n t i t i e s o f w a l l r o c k , equal t o o n e - t e n t h and o n e - t w e n t i e t h o f the volume o f t h e u l t r a m a f i t e s , r e s p e c t i v e l y , would have to be a s s i m i l a t e d to p r o v i d e the p r e s e n t s u l p h u r i s o t o p i c c o m p o s i t i o n s . In the Q u i l l Creek complex, f o r example, about 30 p e r c e n t s u l p h u r c o n t a m i n a t i o n i s i n d i c a t e d by s u l p h u r i s o t o p i c d a t a . Assuming 0.25 weigh t p e r c e n t s u l p h u r i n t h e i n i t i a l magma (based on a comparable v a l u e i n the d u n i t e ) and 1.5 volume p e r c e n t s u l p h u r i n s u r r o u n d i n g w a l l r o c k s (an approximate megascopic e s t i m a t e d e r i v e d d u r i n g d e t a i l e d mapping) and u s i n g a u n i t volume (width x lm x 1m) one can c a l c u l a t e t h a t a u n i t volume o f a p p r o x i m a t e l y 20 c u b i c meters o f w a l l r o c k ( p y r i t i c a r g i l l a c e o u s and t u f f a c e o u s sediments) must have been added t o an u l t r a m a f i c u n i t volume o f about 200 c u b i c m e t e r s . These f i g u r e s a r e o n l y a p p r o x i m a t e , b ut they i n d i c a t e t h a t a s u b s t a n t i a l a d d i t i o n o f w a l l r o c k m a t e r i a l would be n e c e s s a r y . Evidence o f c o u n t r y r o c k c o n t a m i n a t i o n o f t h i s magnitude i s n o t a p p a r e n t a f t e r a d e t a i l e d s t u d y o f p e t r o g r a p h y and rock g e o c h e m i s t r y o f t h e Q u i l l Creek complex ( C h a p t e r 3 ) . S e v e r e s e r p e n t i n i z a t i o n o f the s i l l d u r i n g a l a t e r r e g i o n a l metamorphic e v e n t may have o b l i t e r a t e d o b v i o u s i n d i c a t i o n s o f c o n t a m i n a t i o n , such as g r a p h i t e i n t e r g r o w t h s and odd m i n e r a l i n c l u s i o n s . F i e l d data i n d i c a t e l o c a l p a r t i a l a s s i m i l a t i o n o f w a l l r o c k as e v i d e n c e d by s m a l l i n c l u s i o n s (one to a few meters a c r o s s ) i n b a s a l p a r t s o f the p e r i d o t i t i c s i l l . In t o t a l , such i n c l u s i o n s appear to r e p r e s e n t an al m o s t n e g l i g i b l e p r o p o r t i o n o f the volume o f t h e t o t a l complex and even i f o r i g i n a l l y r i c h i n p y r i t e i t i s d i f f i c u l t t o see how these 152 i n c l u s i o n s c o u l d have s u p p l i e d t he q u a n t i t y o f s u l p h u r n e c e s s a r y t o gen e r a t e t h e observed i s o t o p i c c o m p o s i t i o n s . Bulk c h e m i s t r y o f the complex i s s i m i l a r t o t h a t o f upper mantle p y r o l i t e (see C h a p t e r 3) and t r a c e element d a t a show no obvious e f f e c t s o f b u l k a s s i m i l a t i o n o f c o u n t r y rock by the Q u i l l Creek magma. B a r k e r (1975) demonstrates t h a t h o r n f e l s e d i n c l u s i o n s i n the S t i l l w a t e r i n t r u s i o n were d e p l e t e d i n S i C ^ , Z ^ ^ ^ O j R b ^ O j K ^ O , a n f j H^O. Thus, magma c o n t a m i n a t i o n by c o u n t r y rock a s s i m i l a t i o n may i n v o l v e s p e c i f i c elements o n l y and i n c o r p o r a t i o n o f s e l e c t e d elements o f the w a l l r o c k i n t o a magma might n o t be r e c o g n i z e d e a s i l y b e c a u s e , as McBirney (1979) p o i n t s o u t , t he a d d i t i o n o f m a t e r i a l to a magma may not g r e a t l y a l t e r t h e d i f f e r e n t i a t i o n sequence o f t h a t magma, but j u s t the p r o p o r t i o n s o f the end p r o d u c t s . Mainwaring and N a l d r e t t (1977) p r o v i d e a d e t a i l e d a c c o u n t o f w a l l r o c k c o n t a m i n a t i o n o f the Water Hen i n t r u s i o n . The s u l p h u r i s o t o p i c d a t a r e q u i r e t h a t about 75 p e r c e n t o f the s u l p h u r i n the magmatic s u l p h i d e s be d e r i v e d from wal1 r o c k . A p p r o p r i a t e abundance e s t i m a t e s o f s u l p h u r a r e not a v a i l a b l e t o p e r m i t mass b a l a n c e c a l c u l a t i o n s , but i t i s c l e a r t h a t a g r e a t e r degree o f c o n t a m i n a t i o n than t h a t c i t e d i n the Q u i l l Creek example must have o c c u r r e d , i f a l l contaminant s u l p h u r was c o n t r i b u t e d by b u l k a s s i m i l a t i o n o f w a l l r o c k s . I t i s d i f f i c u l t t o c o n c e i v e contam-i n a t i o n and t o t a l a s s i m i l a t i o n o f such a magnitude d e s p i t e t h e f a c t t h a t e v i d e n c e f o r some a s s i m i l a t i o n i s overwhelming. More r e c e n t l y , ( N a l d r e t t and Macdonald, 1981) have assumed such massive a s s i m i l a t i o n i n t h e case o f t h e Sudbury I r r u p t i v e and have s p e c u l a t e d t h a t t he a d d i t i o n a l s i l i c a c o n t r i b u t e d t o s u l p h u r s a t u r a t i o n and development o f an i m m i s c i b l e s u l p h i d e l i q u i d . In summary, i t seems l i k e l y t h a t some s u l p h u r might be added by 153 bulk a s s i m i l a t i o n o f w a l l r o c k , but t h i s i s u n l i k e l y t o be a complete answer i n a l l ca s e s o f s u l p h u r c o n t a m i n a t i o n . I t i s o f i n t e r e s t t o note t h a t b u l k c o n t a m i n a t i o n o f a n h y d r i t e and c o a l , as proposed by G o d T e v s k i i and Grinenko (1963) i n the case o f t h e N o r i l ' s k s u l p h u r i s o t o p e r a t i o s , does n o t i n v o l v e massive a d d i t i o n o f s i l i c a t e s t o the magma. In c o n t r a s t to b u l k a s s i m i l a t i o n , i n c o n g r u e n t m e l t i n g o f p y r i t e and complete breakdown o f p y r i t e i n t h e c o n t a c t a u r e o l e i n v o l v e a f l u i d phase which must be t r a n s m i t t e d t o the magma from the c o u n t r y r o c k . Such t r a n s p o r t need not i n v o l v e l a r g e q u a n t i t i e s o f o t h e r w a l l r o c k components. Inc o n g r u e n t M e l t i n g o f P y r i t e At temperatures above 743°C p y r i t e m e l t s i n c o n g r u e n t l y t o p y r r h o t i t e p l u s s u l p h u r ( K u l l e r u d and Yoder, 1959). U l t r a m a f i c magmas approach 1600°C ( N i s b e t e t a l _ . , 1977; N a l d r e t t , 1972; N e s b i t t e t a l _ . , 1979) and i f o n l y h a l f t h a t temperature i s m a i n t a i n e d a t the c o n t a c t by heat c o n d u c t i o n (see J a e g e r , 1968) a s u f f i c i e n t l y h o t c o n t a c t zone e x i s t s t o produce d i s s o c i a t i o n o f p y r i t e t o p y r r h o t i t e p l u s s u l p h u r . A s u l p h u r d e p l e t i o n a u r e o l e c o n t a i n i n g p y r r h o t i t e i s an e x p e c t e d p r o d u c t o f t h i s p r o c e s s . Some g e n e r a l d e s c r i p t i o n s i n the l i t e r a t u r e s u g g e s t t h a t d i s s o c i a t i o n o f p y r i t e i s a r e a s o n a b l e s o u r c e o f s u l p h u r f o r contamin-a t i o n o f m a f i c and u l t r a m a f i c magmas. L i e b e n b e r g (1970) d e s c r i b e s a p y r r h o t i t i c c o n t a c t zone a d j a c e n t t o B u s h v e l d r o c k s where about 70 p e r c e n t o f s u l p h u r i n the s u l p h i d e s i n ma r g i n a l r o c k s o f the complex seems t o have been d e r i v e d from w a l l r o c k . S i m i l a r l y , Mainwaring and N a l d r e t t (1977) note p y r r h o t i t e i n w a l l r o c k s a d j a c e n t t o the Water Hen i n t r u s i o n , whereas e l s e w h e r e t h e dominant s u l p h i d e i n the c o u n t r y r o c k s ( V i r g i n i a S l a t e ) i s p y r i t e . C e r t a i n l y t h e s e examples l e n d credence 154 to t h e p o s s i b i l i t y o f i n c o n g r u e n t m e l t i n g o f p y r i t e as a s o u r c e o f contaminant s u l p h u r . I f t h e r e s u l t i n g s u l p h u r i s t o be i n c o r p o r a t e d i n t o t h e u l t r a m a f i c magma a t r a n s p o r t mechanism i s r e q u i r e d . T r a n s f e r o f s u l p h u r t o the magma must be as a f l u i d drawn i n t o an u n d e r s a t u r a t e d magma, p o s s i b l y i n p a r t t h r o u g h f r a c t u r e s d e v e l o p e d a t the time o f magma emplacement. T h i s f l u i d would c o n s i s t o f a m i x t u r e o f H^O and CC^ i n g r a p h i t e - f r e e systems, whereas i n g r a p h i t i c r o c k s s i g n i f i c a n t p r o p o r t i o n s o f o t h e r v o l a t i l e s p e c i e s , such as CH^, CO, and W^i might a l s o be p r e s e n t (Ohmoto and K e r r i c k , 1977). S u l p h u r from such a s o u r c e c o u l d be i n s e v e r a l forms. In s e d i m e n t a r y r o c k s c o n t a i n i n g o r g a n i c m a t t e r , such as are a d j a c e n t t o both the Water Hen i n t r u s i o n and the Kluane complexes, the o x i d a t i o n s t a t e o f t h e f l u i d would be b u f f e r e d by m i n e r a l s such as p y r i t e , p y r r h o t i t e , g r a p h i t e , m a g n e t i t e , q u a r t z , and s i l i c a t e s , and might be about on the q u a r t z - f a y a l i t e - m a g n e t i t e b u f f e r . In t h i s c a s e reduced s u l p h u r would be p r o p o r t i o n a t e l y more abundant than any o x i d i z e d s u l p h u r s p e c i e s and as such would have l i t t l e e f f e c t on the normal d i f f e r e n t i a t i o n o f t h e magma e x c e p t t o promote s u l p h u r s a t u r a t i o n . Complete D i s s o c i a t i o n o f P y r i t e At 1092° p y r r h o t i t e m e l t s , y i e l d i n g i m m i s c i b l e i r o n - r i c h and s u l p h u r -r i c h l i q u i d s ( A r n o l d , 1971). The c o n t a c t temperature o f a magma f l o w i n g l a t e r a l l y can be m a i n t a i n e d v i r t u a l l y a t the i n i t i a l temperature o f t h e i n t r u s i o n f o r t h e d u r a t i o n o f f l o w ( J a e g e r , 1968; Hess, 1960) and t h e r e f o r e c o n t a c t t e m p e r a t u r e s a s s o c i a t e d w i t h a f l o w i n g u l t r a m a f i c magma may v e r y w e l l be g r e a t e r than t h e temperature r e q u i r e d s i m p l y f o r d i s s o c i a t i o n o f p y r i t e . In some cases where s u l p h u r i s o t o p i c d a t a i n d i c a t e t h a t s u b s t a n t i a l w a l l r o c k s u l p h u r was c o n t r i b u t e d t o an u l t r a m a f i c magma, no p y r r h o t i t e 1 5 5 h a l o i s found, r a t h e r a zone c o n t a i n i n g no s u l p h i d e s e x i s t s . Such i s t h e case f o r c o n t a c t zones a d j a c e n t t o t h e Q u i l l Creek s i l l ( C h a p t e r 4 ) . Here t h e w a l l r o c k i s c h a r a c t e r i z e d by small amounts o f h e m a t i t e and m a g n e t i t e a l o n g s l i p s and f r a c t u r e s , i n c o n t r a s t to d i s s e m i n a t e d p y r i t e e l s e w h e r e t h r o u g h the u n i t . The example i s f a r from c l e a r - c u t because o f t h e s h e a r e d n a t u r e o f t h e s i l l c o n t a c t s , but i t may r e p r e s e n t a case i n which some o f t h e s u l p h u r was o b t a i n e d from complete d i s s o c i a t i o n o f p y r i t e and t h e consequent a v a i l a b i l i t y o f s u l p h u r f o r i n c o r p o r a t i o n i n t o the magma. In g e n e r a l , both o x i d i z e d and reduced s u l p h u r s p e c i e s w i l l be p r e s e n t , and both the o x i d a t i o n s t a t e o f t h e f l u i d and the temperature w i l l determine which form o f s u l p h u r w i l l predominate. SUMMARY OF THE MODEL A number o f g a b b r o i c / u l t r a m a f i c i n t r u s i o n s show e v i d e n c e o f w a l l -rock and/or s u l p h u r c o n t a m i n a t i o n . M i n e r a l c o n s t i t u e n t s , such as g r a p h i t e , s p i n e l , c o r d i e r i t e , and b i o t i t e , s u g g e s t c o n t a m i n a t i o n o f many o f t h e i n t r u d i n g magmas. These m i n e r a l s are g e n e r a l l y o f l o c a l e x t e n t and are commonly a s s o c i a t e d s p a t i a l l y w i t h w a l l r o c k x e n o l i t h s . Most g a b b r o i c / u l t r a m a f i c complexes c o n t a i n s u l p h i d e s w i t h s u l p h u r i s o t o p e v a l u e s near 0 p e r m i l However, a s i g n i f i c a n t number o f magmatic n i c k e l -copper s u l p h i d e d e p o s i t s show e v i d e n c e t h a t s u b s t a n t i a l c o n t a m i n a t i o n by w a l l r o c k s u l p h u r has o c c u r r e d . The most c o n v i n c i n g e v i d e n c e f o r t h i s i s o b t a i n e d from s u l p h u r i s o t o p e d a t a , which shows t h a t where c o n t a m i n a t i o n i s i n d i c a t e d s u l p h u r i s o t o p e v a l u e s o f t h e d e p o s i t s l i e between 0 p e r m i l and t h e i s o t o p i c c o m p o s i t i o n o f s u l p h u r i n nearby r o c k s . 87 8fi Other d a t a , such as oxygen i s o t o p e s and S r / S r r a t i o s , p r o v i d e f u r t h e r 156 e v i d e n c e f o r magma c o n t a m i n a t i o n , e i t h e r i n t h e form o f c i r c u l a t i n g ground waters o r by c o u n t r y rock a s s i m i l a t i o n . The t i m i n g o f magma c o n t a m i n a t i o n by e x t e r n a l s u l p h u r i s v a r i a b l e and may i n c l u d e v i r t u a l l y a l l s t a g e s i n the c r y s t a l l i z a t i o n and d i f f e r -e n t i a t i o n o f a g a b b r o i c / u l t r a m a f i c complex. C o n t a m i n a t i o n may o c c u r : (1) d u r i n g a s c e n t o f the d i a p i r ; (2) im m e d i a t e l y on i n i t i a l i n t r u s i o n o f t h e magma; (3) d u r i n g p r o g r e s s i v e d i f f e r e n t i a t i o n and/or l a t e r a l flow o f t h e magma; and (4) d u r i n g v a r i o u s s t a g e s o f c r y s t a l l i z a t i o n and s o l i d i f i c a t i o n o f t h e s i l i c a t e l i q u i d . P y r i t e i n w a l l r o c k s i s c o n s i d e r e d t o be t h e most l i k e l y g e n e r a l s o u r c e f o r s u l p h u r c o n t r i b u t e d t o u l t r a m a f i c magmas, a l t h o u g h i n s p e c i f i c c a s e s o t h e r m i n e r a l s , i n c l u d i n g s u l p h a t e s , appear t o have been i m p o r t a n t s o u r c e s . S u l p h u r t r a n s f e r t o t h e magma can o c c u r by b u l k c o u n t r y rock a s s i m i l a t i o n , o r by f l u i d i n g r e s s where the f l u i d d e r i v e s s u l p h u r from t h e c o n t a c t zone by i n c o n g r u e n t m e l t i n g o f p y r i t e o r by d i s s o c i a t i o n o f p y r i t e . A l l o f t h e s e p r o c e s s e s may be i m p o r t a n t mechanisms o f s u l p h u r d e r i v a t i o n , b u t i n most cases i t would appear t h a t b u l k a s s i m i l a t i o n o f w a l l r o c k i s the l e a s t i m p o r t a n t mechanism q u a n t i t a t i v e l y . C o n s e q u e n t l y , t r a n s f e r o f s u l p h u r i n t o the magma appears to be m a i n l y by some form o f v o l a t i l e t r a n s p o r t . The v o l a t i l e phase i s p r o b a b l y m o s t l y water as i n d i c a t e d by t h e presence o f hornblende and p h l o g o p i t e i n some r o c k s t h a t have i n c o r p o r a t e d a s u b s t a n t i a l amount o f non-magmatic s u l p h u r . An i d e a l i z e d o u t l i n e o f t h e model i s summarized i n F i g u r e 3 where p o s s i b l e s t a g e s o f c o n t a m i n a t i o n , development o f i m m i s c i b l e s u l p h i d e l i q u i d , g r a v i t a t i o n a l s e t t l i n g w i t h p o s s i b l e i n j e c t i o n , and f i n a l l y , c o n s o l i d a t i o n a r e i m p l i e d . 157 A A A A A ^ V A ^ W A t L R a C ^ . i.i.".zrr>C ^-Ar*s! a A A a A' A" I M M I S C I B L E S U L P H I D E ] B L E B S » A A A"£ 'A" A. A A A A A A A A~ A A A A A A A A A A A A A A ^ A A A A A A A A A A A A P E R I D O T I T E Q A B B R O A A A A A A A A A A A A A V "A A_A A A A A A A A A A * I | i A A A A A A A A A A A i . A A A r\ . V, aiwc 'nAno V»c A A J A A A A A A A A A A A A A A A ^ M A S S I V E P O D S O F A A A i i A A A A A A A A A A A A A A A , — , Q U I O L I H C A A I A A A A A A A A A A A A A A A * NI-CU SULrHIUt. a i A A A A A A A A A A A A A A A A A A A A A A A A . A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A fc. A ^ A A A A A A V A i u u A A A A t A A A A A A A - * * - - \ i — _ _ _ _ _ _ A . A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A . A A A A A A A . A A A A A A A A i A A A A A . A A A A A A A A A A A. _ _ _ A A A A _ _ _ _ _ _ _ . - . b A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A . A A A A A A A A - A A A <3 A A A A I N J E C T E D ~ A ~ A _ . A ' V A V S U L P H I D E W \ i _ - * - - - *i A A A A A A A A A A A A A A A A A A A A A ft**—*"^ A A A A"A" A"A "A "A"A'"A_ A" A A A ^ A A A"_""A""'A" A A A A A A A A A A A A A A A A A A A A A A A A A A A » . . . . . . . . A . « A A A , VOLCANIC TUFF _ _ J SHALE [_• SULPHUR-BEARING ROCK F i g u r e 3 . Schematic r e p r e s e n t a t i o n o f the s u l p h u r c o n t a m i n a t i o n model f o r g a b b r o i c o r u l t r a m a f i c i n t r u s i o n s . A d i a p i r o f upper mantle m a t e r i a l r e -c e i v e s c o ntaminant s u l p h u r (as shown by arrows) from e i t h e r i n t r u d e d coun-t r y r o c k s d u r i n g the a s c e n t o f the d i a p i r , shown i n ( a ) , o r w a l l r o c k s a t the l e v e l o f f i n a l emplacement and b e f o r e o r d u r i n g l a t e r a l f l o w o f the magma, shown i n ( b ) . The magma becomes s a t u r a t e d w i t h r e s p e c t t o s u l p h u r and s u l p h i d e s b e g i n t o accumulate a t the base o f the i n t r u s i o n d u r i n g l a t e r a l f l o w , shown i n ( c ) . L a t e r a l f l o w s t o p s and the magma becomes e s s e n -t i a l l y s o l i d i f i e d w i t h massive pods o f s u l p h i d e s e i t h e r a t i t s base o r i n j e c t e d i n t o w a l l r o c k . I n j e c t e d s u l p h i d e s may s u f f e r f u r t h e r s u l p h u r c o n t a m i n a t i o n by w a l l r o c k s u l p h u r d u r i n g the i n j e c t i o n p r o c e s s , as i n d i -c a t e d i n ( d ) . A p a r t i a l o r complete s u l p h u r d e p l e t i o n h a l o e x i s t s i n w a l l r o c k i m m e d i a t e l y a d j a c e n t t o the u l t r a m a f i c body. 158 ECONOMIC IMPLICATIONS N a l d r e t t and Macdonald (1981) s u g g e s t t h a t major r i f t zones i n which m a f i c magmatism has o c c u r r e d , a r e prime t a r g e t s f o r r e g i o n a l e x p l o r a t i o n because t h e r e a c t i o n o f m a f i c magmas w i t h c r u s t a l m a t e r i a l has p l a y e d an i m p o r t a n t r o l e i n the f o r m a t i o n o f a s s o c i a t e d n i c k e l -copper s u l p h i d e o r e s . One o f t h e i r p r o p o s a l s i s t h a t t h e Sudbury I r r u p t i v e magma may have become h i g h l y c o n t a m i n a t e d by q u a r t z - r i c h m a t e r i a l , r e s u l t i n g i n an i n c r e a s e d SiO^ c o n t e n t . I r v i n e (1975) has shown t h a t s i l i c i f i c a t i o n o f a m a f i c magma can promote s u l p h i d e s a t u r a -t i o n and su g g e s t s t h a t t h i s mechanism may be r e s p o n s i b l e f o r the n i c k e l -c o p p e r ore c o n c e n t r a t i o n s a t Sudbury. F or t h e Water Hen and N o r i l ' s k i n t r u s i o n s , both r e l a t e d t o i n t r a c o n t i n e n t a l r i f t i n g , N a l d r e t t and Macdonald (1981) s u g g e s t t h a t a s s i m i l a t i o n o f c o u n t r y rock s u l p h u r may have been t h e c r u c i a l f a c t o r i n the f o r m a t i o n o f n i c k e l - c o p p e r s u l p h i d e d e p o s i t s . A s u l p h u r c o n t a m i n a t i o n model has been shown here to r e p r e s e n t a p l a u s i b l e g e n e t i c model f o r many g a b b r o i c and u l t r a m a f i c complexes, most o f which have a s s o c i a t e d w i t h them n i c k e l - c o p p e r s u l p h i d e d e p o s i t s . Examples i n c l u d e the N o r i l ' s k s i l l s , Kluane complexes, Water Hen i n t r u s i o n , Rana i n t r u s i o n , B u s h v e l d complex, and some o f t h e F i n n i s h u l t r a m a f i t e s . There can be l i t t l e q u e s t i o n t h a t , i n the end r e s u l t , s u l p h u r s a t u r a t i o n i n the p a r e n t magma i s the e s s e n t i a l component i n the d e v e l o p -ment o f i m m i s c i b l e s u l p h i d e l i q u i d s t h a t a r e tho u g h t to have produced most o f t h e massive n i c k e l - c o p p e r s u l p i d e d e p o s i t s i n t h e w o r l d . E v i d e n c e has been p r e s e n t e d t h a t as much as 75 p e r c e n t o f t h e s u l p h u r i n some n i c k e l - c o p p e r s u l p h i d e b o d i e s was d e r i v e d from wal1 r o c k . Perhaps t h i s 159 one i n g r e d i e n t , s u l p h u r - b e a r i n g w a l l r o c k s , i s the key. I t i s l i k e l y t h a t i n some o f t h e cases c i t e d s a t u r a t i o n might n o t have o c c u r r e d u n t i l much l a t e r i n the d i f f e r e n t i a t i o n h i s t o r y had not l a r g e amounts o f s u l p h u r been p u l l e d i n t o the magma from a d j a c e n t p y r i t i c w a l l r o c k . In f a c t , i t seems p o s s i b l e t h a t i n some cases s u l p h u r s a t u r a t i o n might never have o c c u r r e d w i t h o u t s u l p h u r c o n t a m i n a t i o n . The i m p l i c a t i o n s o f t h i s model from a p r o s p e c t i n g p o i n t o f view a r e e q u a l l y s t r i k i n g . Because s u l p h u r - b e a r i n g c o u n t r y r o c k s o b v i o u s l y have p o t e n t i a l t o promote the development o f n i c k e l - c o p p e r s u l p h i d e d e p o s i t s , e x p l o r a t i o n f o r such d e p o s i t s s h o u l d be c o n c e n t r a t e d where g a b b r o i c and u l t r a m a f i c i n t r u s i o n s a r e i n c o n t a c t w i t h s u l p h u r - b e a r i n g c o u n t r y r o c k . I f t h e main s u l p h u r - b e a r i n g m i n e r a l i n the w a l l r o c k i s p y r i t e then s u l p h u r d e p l e t i o n h a l o e s marked by e i t h e r p y r r h o t i t e ( s u l p h u r d e p l e t i o n by i n c o n g r u e n t m e l t i n g o f p y r i t e ) o r absence o f both p y r i t e and p y r r h o t i t e ( t o t a l d i s s o c i a t i o n o f p y r i t e , perhaps w i t h some i r o n o x i d e as a p r o d u c t ) , i n d i c a t e t h e l i k e l i h o o d t h a t s u l p h u r c o n t a m i n a t i o n o f the m a f i c o r u l t r a m a f i c magma may have o c c u r r e d and t h a t a hi g h p o t e n t i a l e x i s t s f o r development o f i m m i s c i b l e s u l p h i d e s . From t h i s s t a g e e x p l o r a t i o n would proceed a c c o r d i n g t o the c l a s s i c a l model because once an i m m i s c i b l e s u l p h i d e l i q u i d d e v e l o p s the s o u r c e o f the s u l p h u r i s i r r e l e v a n t t o t h e problems o f g r a v i t a t i o n a l s e t t l i n g , i n j e c t i o n , a l t e r a t i o n , e t c . ACKNOWLEDGEMENTS F i n a n c i a l s u p p o r t f o r t h i s s t u d y was o b t a i n e d m a i n l y from t he N a t i o n a l C o u n c i l o f Canada through an N.R.C. P o s t g r a d u a t e S c h o l a r s h i p 160 t o S.W. Campbell and o p e r a t i n g g r a n t s t o Dr. A . J . S i n c l a i r . L a t e r c o n t r i b u t i o n s , t o a i d i n c o m p l e t i o n o f s p e c i f i c a s p e c t s o f t h e s t u d y , came from t h e A r t i e and A l p i n e I n s t i t u t e o f The U n i v e r s i t y o f B r i t i s h Columbia, Western Mines L i m i t e d , and Orequest, Vancouver. 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S c i . , 273, 207-239. 164 CHAPTER 6 CONCLUSIONS 165 F i e l d work i n the Kluane Ranges and a s s o c i a t e d l a b o r a t o r y s t u d i e s have l e a d t o an u n d e r s t a n d i n g o f environments o f d e p o s i t i o n o f p r i n c i p a l s t r a t i g r a p h i c u n i t s i n t h e Q u i l l Creek and White R i v e r a r e a s . V o l c a n i c and v o l c a n i c l a s t i c s e c t i o n s o f Lower Permian S t a t i o n Creek Formation were d e p o s i t e d i n a subaqueous, p r o b a b l y v o l c a n i c a r c , environment. The T r a n s i t i o n Zone was formed i n a r e s t r i c t e d b a s i n o r b r a c k i s h w a t e r e n v i r o n m e n t . A subaqueous, p o s s i b l y b a c k - a r c b a s i n , c o n t i n u e d ( w i t h i n c r e a s e d c i r c u l a t i o n ) t h r o u g h o u t d e p o s i t i o n o f the Lower Permian Hasen Creek F o r m a t i o n . Upper T r i a s s i c N i k o l a i Greenstone was d e p o s i t e d i n a v e r y s h a l l o w subaqueous t o s u b a e r i a l environment and may r e p r e s e n t r i f t v o l c a n i s m i n a b a c k - a r c b a s i n . Kluane gabbro-u l t r a m a f i c complexes l i e c o n f o r m a b l y w i t h i n r o c k s o f the T r a n s i t i o n Zone and Hasen Creek F o r m a t i o n . Maple Creek gabbro dykes and s i l l s o c c u r i n a l l Permian r o c k s and i n t o t h e N i k o l a i Greenstone. A major component o f t h i s s t u d y was concerned w i t h t h e o r i g i n o f Kluane g a b b r o - u l t r a m a f i c complexes, e s p e c i a l l y the l a r g e Q u i l l Creek complex. D e t a i l e d f i e l d , p e t r o g r a p h i c , and chemical ( i n c l u d i n g m i c r o p r o b e ) a n a l y s e s i n d i c a t e t h e f o l l o w i n g . The complexes a r e Lower T r i a s s i c s i l l - o r s h e e t - l i k e i n t r u s i o n s , d i v i s i b l e i n t o a Lower Group - l a r g e l y u l t r a m a f i c b o d i e s ( w i t h a s s o c i a t e d n i c k e l -c o p p e r d e p o s i t s ) w i t h i n T r a n s i t i o n Zone r o c k s , and an Upper Group -g a b b r o - p e r i d o t i t e i n t r u s i o n s (with no known a s s o c i a t e d n i c k e l - c o p p e r d e p o s i t s ) w i t h i n Hasen Creek F o r m a t i o n . Lower Group complexes c o n s i s t o f p e r i d o t i t e u n d e r l a i n by d u n i t e and have a b o r d e r zone o f o l i v i n e gabbro. Upper Group complexes a r e composed o f p e r i d o t i t e o v e r l a i n by gabbro. The u l t r a m a f i c r o c k s are p l a g i o c l a s e - b e a r i n g and p h l o g o -p i t i c b i o t i t e ( o r more r a r e l y , h o r n b l e n d e ) i s a minor primary 166 c o n s t i t u e n t o f the p e r i d o t i t e s . D i f f e r e n t i a t i o n o f the Lower Group complexes was by f l o w w i t h some g r a v i t y a c c u m u l a t i o n , whereas Upper Group complexes d i f f e r e n t i a t e d by g r a v i t y a c c u m u l a t i o n . C h e m i c a l l y , r o c k s o f t h e Lower and Upper Group i n t r u s i o n s a r e p y r o x e n i t i c and p e r i d o t i t i c k o m a t i i t e s . Bulk chemical c o m p o s i t i o n o f t h e Q u i l l Creek complex i s s i m i l a r t o t h a t o f p y r o l i t e , and c a l c u l a t i o n s show t h a t the complex c o u l d have formed by i n t r u s i o n o f an upper mantle d i a p i r a f f e c t e d by a b o u t 40 p e r c e n t p a r t i a l m e l t i n g . The o c c u r r e n c e o f t h e s e Lower T r i a s s i c k o m a t i i t i c s i l l s i n the Kluane Ranges o f the Canadian C o r d i l l e r a shows t h a t p y r o x e n i t i c and p e r i d o t i t i c k o m a t i i t e s are n o t unique to the Precambrian S h i e l d . F i e l d , p e t r o g r a p h i c , and chemical data f o r the Upper T r i a s s i c Maple Creek gabbros i n d i c a t e t h a t they a r e s i m i l a r t o b a s a l t s o f the N i k o l a i G r e e n s t o n e . The gabbros a r e c o n s i d e r e d t o be remnants o f a f e e d e r system f o r t h e b a s a l t s . The c h e m i s t r y o f both t h e s e rock t y p e s i s i n t e r m e d i a t e between t h a t o f b a s a l t i c k o m a t i i t e s and t h o l e i i t e s . Copper lode d e p o s i t s a r e u b i q u i t o u s i n r o c k s o f t h e Kluane Ranges and were s t u d i e d i n d e t a i l . A g e n e r a l c l a s s i f i c a t i o n a f t e r Read and Monger (1976) has been f u r t h e r s u b d i v i d e d by the w r i t e r as o u t l i n e d i n t h e accompanying t a b l e ( T a b l e 1 ) . A g e n e r a l g e o l o g i c a l i n t e r p r e t a t i o n o f g e n e s i s f o r each o f t h e p r i n c i p a l t y p e s o f m i n e r a l d e p o s i t s i s i n c l u d e d i n t h i s t a b l e . Most o f t h e copper l o d e d e p o s i t s o c c u r i n a narrow, r o u g h l y 10 km w i d e , b e l t t h a t t r e n d s n o r t h w e s t e r l y a l o n g the l e n g t h o f the Kluane Ranges. The f i r s t e c o n o m i c a l l y s i g n i f i c a n t development o f copper m i n e r a l i z a t i o n o c c u r r e d d u r i n g Lower T r i a s s i c time w i t h f o r m a t i o n o f n i c k e l - c o p p e r d e p o s i t s a s s o c i a t e d w i t h Kluane TABLE 1. Copper Lode Deposits i n the Kluane Ranges CLASSIFICATION Read and Monger* PRINCIPAL CHARACTERISTICS This Study INTERPRETATION OF GENESIS EXAMPLES 1. Copper i n S k o l a i Group. 2. Ni-Cu-Pt. 3. Copper i n N i k o l a i Green-stone. 4. Porphyry Cu deposi ts. a) S t r a t i form i n V o l c a n i c rocks. b) Copper i n v e i n s . c) Copper i n T r a n s i t i o n Zone. Ni-Cu a s s o c i a t e d w i t h u l t r a m a f i c i n t r u s i o n s . a) Native Copper. b) Copper i n v e i n s . Copper-molybdenum i n f e l s i c i n t r u s i o n s . 1. Disseminated and lens c h a l c o p y r i t e and p y r i t e . 2. In m i n e r a l i z e d h o r i z o n p a r a l l e l to and s t r a d d l i n g i n t e r f a c e between flow and t u f f . 1. C h a l c o p y r i t e & p y r r h o t i t e i n q u a r t z - e p i d o t e -c a ' l c i t e v e i n s . 2. Cross c u t t i n g veins and seams p a r a l l e l to f o l i a t i o n . 3. Occur w i t h i n m i n e r a l i z e d h o r i z o n . 1. F i n e l y disseminated p y r i t e and minor c h a l c o p y r i t e i n t h i n l y banded a r g i l l i t e . 2. G e n e r a l l y stratabound. 3. A l s o f r a c t u r e coatings i n a r g i l l a c e o u s limestone. '  1. At base o f u l tramafi te o r f o o t w a l l rocks. 2. Disseminated t o n e t - t e x t u r e d to massive o r e , going from top to bottom. 3. Ore pods i n f o o t w a l l rocks c o n t a i n s m a l l , rounded x e n o l i t h s o f w a l l r o c k . 1. Concentrated s p o r a d i c a l l y i n crude t a b u l a r zones. 2. Occurs i n veins and as disseminations i n d e v i t r i f i e d flow tops.  1. Copper sulphides occur In veins that c r o s s cut flows and i n amygdules. 2. I n t i m a t e l y a s s o c i a t e d w i t h metamorphic m i n e r a l s . P y r i t e , c h a l c o p y r i t e , and molybdenite occur i n f r a c t u r e s w i t h q u a r t z . F e l s i c stock i n t r u d e s along d i s c o n -f o r n i i t y between Hasen Creek Fm. and N i c k o l a i Greenstone. Syngenetic o r e a r l y d i a g e n e t l c . Pickhandle p r o p e r t y . E p i g e n e t i c ; formed by l o c a l m o b i l i z a t i o n o f p r e - e x i s t i n g s u l p h i d e s . Syngenetic or e a r l y d i a g e n e t i c . Magmatic; formed by s e p a r a t i o n of-i m m i s c i b l e s u l p h i d e l i q u i d from magma and g r a v i t y accumulation; l o c a l l y , m o b i l i z a t i o n o f some ore pods. Product o f e x t e n s i v e s u b a e r i a l weathering of the b a s a l t p i l e . Formed d u r i n g low grade r e g i o n a l metamorphism i n a r e l a t i v e l y open system. Pickhandle p r o p e r t y . Canalask p r o p e r t y . Wellgreen p r o p e r t y . Arch Creek pro p e r t y . Linda Creek p r o p e r t y . Canalask p r o p e r t y . S i l v e r C i t y p r o p e r t y . S i l v e r C i t y p r o p e r t y . A l i c e Lake Mines property. Q u i l l Creek Mines prop e r t y . Johobo p r o p e r t y .  cn D e p o s i t i o n from geothermal system Cork p r o p e r t y , r e l a t e d to i n t r u s i o n s . 1 A f t e r Read and Monger (1976). 168 g a b b r o - u l t r a m a f i c complexes. A s t u d y o f the s u l p h u r i s o t o p i c c o m p o s i t i o n s o f l o d e copper d e p o s i t s i n t h e Kluane Ranges c o n t r i b u t e s s u b s t a n t i a l l y t o an under-s t a n d i n g o f " o r e " g e n e s i s . I s o t o p i c data c o n f i r m g e o l o g i c i n t e r p r e t a -t i o n s and p r o v i d e i n s i g h t i n t o s o u r c e s o f s u l p h u r and c e r t a i n a s p e c t s o f i t s h i s t o r y d u r i n g m i n e r a l d e p o s i t i o n . The anomalously n e g a t i v e i s o t o p i c v a l u e s f o r n i c k e l - c o p p e r s u l p h i d e b o d i e s a re a p r o d u c t o f s u b s t a n t i a l c o n t a m i n a t i o n o f magmatic s u l p h u r i n the u l t r a m a f i t e by 30 t o 60 p e r c e n t s u l p h u r from w a l l r o c k s i n the T r a n s i t i o n Zone. Assuming t o t a l d i s s o c i a t i o n o f p y r i t e , a 5 t o 10 m wide d e p l e t i o n h a l o a d j a c e n t t o t h e u l t r a m a f i c i n t r u s i o n c o u l d have p r o v i d e d a l l the c o n t a m i n a n t s u l p h u r n e c e s s a r y t o a c c o u n t f o r t h e s u l p h u r i s o t o p i c c o m p o s i t i o n s . Such a d e p l e t i o n h a l o e x i s t s f o r the Kluane complexes. T h i s c o n t a m i n a t i o n o c c u r r e d p r i o r t o o r d u r i n g s e g r e g a t i o n o f an i m m i s c i b l e s u l p h i d e l i q u i d . S u l p h u r i s o t o p e d a t a f o r W e l l g r e e n c o n s t i t u t e one o r p o s s i b l y two p o p u l a t i o n s and t h e r e f o r e one o r perhaps two s t a g e s o f c o n t a m i n a t i o n . I s o t o p i c c o m p o s i t i o n s f o r massive ore pods a t Canalask s u g g e s t an a d d i t i o n a l s t a g e o f c o n t a m i n a t i o n o f the s t i l l l i q u i d s u l p h i d e s d u r i n g and/or a f t e r s u l p h i d e i n j e c t i o n i n t o f o o t w a l l r o c k s . The importance o f p y r i t i c r o c k s w i t h i n t h e zone o f i n t r u s i o n o f c e r t a i n Kluane complexes i s o b v i o u s . S i g n i f i c a n t con-t a m i n a n t s u l p h u r may have been c r u c i a l i n a c h i e v i n g s u l p h u r s a t u r a t i o n o f t h e magma, l e a d i n g t o f o r m a t i o n o f the n i c k e l - c o p p e r d e p o s i t s . In f a c t , i t i s p o s s i b l e t h a t w i t h o u t s u l p h u r c o n t a m i n a t i o n , s u l p h u r s a t u r a t i o n may n o t have o c c u r r e d u n t i l much l a t e r d u r i n g d i f f e r e n t i a t i o n o f t h e complex, and t h e r e f o r e no magmatic d e p o s i t s o f su b s t a n c e would have e v o l v e d . I s o t o p i c data show a c o n t r a s t between s u l p h i d e s i n S t a t i o n Creek 169 Formation and t h o s e i n N i k o l a i Greenstone. S u l p h u r i s o t o p e s f o r both s y n g e n e t i c and v e i n s u l p h i d e s i n t h e S t a t i o n Creek d e f i n e narrow, p o s i t i v e , and a p p a r e n t l y c o i n c i d e n t r a n g e s , s u g g e s t i n g t h a t v e i n m i n e r a l i z a t i o n r e s u l t e d from o n l y l o c a l m o b i l i z a t i o n o f s u l p h u r (and me t a l s ) d u r i n g metamorphism i n a c l o s e d system. S u l p h i d e s i n the N i k o l a i Greenstone show a l a r g e range i n s u l p h u r i s o t o p i c c o m p o s i t i o n , thus d i f f e r i n g markedly from s u l p h i d e s i n S t a t i o n Creek v o l c a n i c r o c k s . The i s o t o p i c v a l u e s , c o u p l e d w i t h f i e l d and m i n e r a l o g i c a l d a t a , i n d i c a t e c o n s i d e r a b l e v a r i a t i o n i n chemical parameters o f t h e ore f l u i d , i n p a r t i -c u l a r , oxygen f u g a c i t y and perhaps pH. Thus the m i n e r a l i z i n g p r o c e s s appears t o have o c c u r r e d i n an open system w i t h more than one s o u r c e o f s u l p h u r needed t o ac c o u n t f o r the wide range i n i s o t o p i c d a t a . Two p o s s i b l e s o u r c e s o f s u l p h u r i n c l u d e connate T r i a s s i c seawater i n lowermost N i k o l a i f l o w s and connate Permian seawater i n u n d e r l y i n g Hasen Creek F o r m a t i o n . A d e t a i l e d e x a m i n a t i o n o f t h e l i t e r a t u r e r e g a r d i n g n i c k e l - c o p p e r d e p o s i t s r e l a t e d t o m a f i c and u l t r a m a f i c i n t r u s i o n s t h r o u g h o u t t he w o r l d i n d i c a t e s t h a t s u l p h u r c o n t a m i n a t i o n i s a common f e a t u r e , and a g e n e r a l s u l p h u r c o n t a m i n a t i o n model f o r t h e o r i g i n o f such d e p o s i t s has been d e v e l o p e d . The model i s v e r i f i e d by p e t r o l o g i c e v i d e n c e o f w a l l r o c k c o n t a m i n a t i o n i n m a f i c and u l t r a m a f i c magmas and by s u l p h u r i s o t o p i c data f o r both t he magmatic s u l p h i d e s and s u l p h u r - b e a r i n g c o u n t r y r o c k s . P y r i t e i n w a l l r o c k s i s c o n s i d e r e d t o be the most l i k e l y g e n e r a l s o u r c e o f s u l p h u r c o n t r i b u t e d t o u l t r a m a f i c magmas, al t h o u g h i n s p e c i f i c cases o t h e r m i n e r a l s , i n c l u d i n g s u l p h a t e s , appear t o have been i m p o r t a n t s o u r c e s . S e v e r a l d i f f e r e n t s t a g e s o f s u l p h u r c o n t a m i n a t i o n a r e p o s s i b l e t h r o u g h o u t c o n s o l i d a t i o n o f the 170 i l l t r a m a f i te and i t s a s s o c i a t e d magmatic s u l p h i d e s , however, the main phase o f c o n t a m i n a t i o n i s g e n e r a l l y e a r l y i n the d i f f e r e n t i a t i o n h i s t o r y o f the magma. S u l p h u r t r a n s f e r t o the magma can o c c u r by bulk c o u n t r y rock a s s i m i l a t i o n o r by f l u i d i n g r e s s where t he f l u i d d e r i v e s s u l p h u r from the c o n t a c t zone by i n c o n g r u e n t m e l t i n g o f p y r i t e o r by complete d i s s o c i a t i o n o f p y r i t e . I t would appear t h a t bulk- a s s i m i l a t i o n i s the l e a s t i m p o r t a n t mechanism q u a n t i t a t i v e l y . Some i m p o r t a n t f e a t u r e s o f t h i s model, h a v i n g economic i m p l i c a t i o n s , a r e : (1) t h e i n t r u s i v e n a t u r e o f the u l t r a m a f i t e ; (2) t h e presence o f s u l p h u r - b e a r i n g c o u n t r y r o c k s o r , more s p e c i f i c a l l y , s u l p h u r -b e a r i n g w a l l r o c k s ; and (3) the presence o f s u l p h u r d e p l e t i o n h a l o e s ( i n p y r i t i c w a l l r o c k s a d j a c e n t t o u l t r a m a f i t e s ) t h a t c o n t a i n e i t h e r p y r r h o t i t e o r no i r o n s u l p h i d e s . 171 REFERENCES A r n d t , N.T., 1977, T h i c k , l a y e r e d p e r i d o t i t e - g a b b r o l a v a flows i n Munro Township, O n t a r i o ; Can. J o u r . E a r t h S c i . , V o l . 14, p. 2620-2637. A r n d t , N.T., N a l d r e t t , A . 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V i n o g r a d o v , A.P., and G r i n e n k o , L.N., 1964, The e f f e c t o f e n c l o s i n g r o c k s on the i s o t o p i c c o m p o s i t i o n o f s u l p h u r i n s u l p h i d e o r e m i n e r a l s ; Geokhimiya, No. 6, p. 491-499. Vogt, J.H.L., 1921, The p h y s i c a l c h e m i s t r y and magmatic d i f f e r e n t i a t i o n i n igneous r o c k s ; J o u r . G e o l . , V o l . 29, p. 319-350. Wager, L.R., and Brown, G.M., 1968, Layered igneous r o c k s ; London, O l i v e r and Boyd. Wenner, D.B., and T a y l o r , H.P., J r . , 1973, Oxygen and hydrogen i s o t o p e s t u d i e s o f the s e r p e n t i n i z a t i o n o f u l t r a m a f i c r o c k s i n o c e a n i c environments and c o n t i n e n t a l o p h i o l i t e complexes; Amer. J o u r . S c i . , V o l . 273, p. 207-239. 179 APPENDIX A l DETAILED GEOLOGY AND HISTORY OF DEVELOPMENT OF INDIVIDUAL PROPERTIES IN THE QUILL CREEK AND WHITE RIVER AREAS 180 COPPER IN SKOLAI GROUP P i c k h a n d l e P r o p e r t y  L o c a t i o n The "M" C l a i m Group i s s i t u a t e d 4.8 km south o f P i c k h a n d l e Lake and about 13 km s o u t h e a s t o f the Canalask a d i t . The p r o p e r t y l i e s between e l e v a t i o n s 2250 f e e t and 4500 f e e t near t he base o f the n o r t h e a s t s l o p e o f Kluane Ranges. H i s t o r y o f Development P. Vers l u c e f i r s t s t a k e d t h e p r o p e r t y i n 1968 and l a t e r r e s t a k e d i t when t h e p r e v i o u s c l a i m s l a s p e d i n 1973. A d d i t i o n a l c l a i m s were added i n 1974 and 1975. A 19.2 km g r i d was c u t on the s o u t h e r n h a l f o f the c l a i m group and P. V e r s l u c e c a r r i e d out t r e n c h i n g i n 1973 and 1974. John S. V i n c e n t L i m i t e d , a c t i n g f o r N i c k e l S y n d i c a t e ( A q u i t a i n e , Home O i l , G e t t y M i n i n g P a c i f i c ) began a program o f mapping, p r o s p e c t i n g , and geochemical sampling i n 1973, but were h a l t e d by poor weather. B r a s c a n Resources L i m i t e d o p t i o n e d t he M Claims i n May, 1975. A g e o l o g i c mapping, p r o s p e c t i n g , and b u l l d o z e r s t r i p p i n g program was conducte d i n t h e summer o f 1975 and was f o l l o w e d up i n 1976 by more d e t a i l e d mapping and p r o s p e c t i n g and a magnetic s u r v e y . The p r o p e r t y was t r a n s f e r r e d t o Western Mines L i m i t e d t h a t same y e a r and the o p t i o n agreement was t e r m i n a t e d i n J u l y , 1976. Geology The p r o p e r t y i s u n d e r l a i n by a sequence o f Lower Permian v o l c a n i c , v o l c a n i c l a s t i c , and s e d i m e n t a r y r o c k s o f S t a t i o n Creek F o r m a t i o n . The u n i t s p r o g r e s s upwards from f l o w s t o medium- and c o a r s e - g r a i n e d t u f f s 181 and l a p i l l i t u f f s , and f i n a l l y to agglomerates and v o l c a n i c b r e c c i a s . The mappable u n i t s a r e , i n o r d e r o f a s c e n d i n g s t r a t i g r a p h i c l e v e l : U n i t 1. I n t i m a t e l y i n t e r b e d d e d grey-brown c h e r t y a r g i l l i t e , b l a c k s h a l e , and f i n e - g r a i n e d green b a s a l t i c a n d e s i t e t u f f s . U n i t 2. White t o p a l e grey c r y s t a l l i n e l i m e s t o n e and c h e r t y 1imestone. U n i t 3. P a l e t o medium green s p a r s e l y v e s i c u l a r t o amyg d a l o i d a l and g e n e r a l l y p i l l o w e d b a s a l t i c a n d e s i t e f l o w s . U n i t 4. T h i n l y bedded b l a c k s h a l y a r g i l l i t e , grey t o b l a c k c h e r t , and grey-brown c h e r t y a r g i l l i t e . U n i t 5. B u f f - c o l o r e d l i m e s t o n e w i t h i n t e r b e d d e d t h i n c h e r t y l a y e r s , up t o 1 cm t h i c k , and l e n s e s o f c h e r t , from 7 t o 15 cm a c r o s s . U n i t 6. Medium t o dark green v o l c a n i c l a s t i c r o c k s , i n c l u d i n g a n d e s i t i c (and minor d a c i t i c ) c o a r s e - g r a i n e d t u f f , l a p i l l i t u f f , and minor hornbl e n d e c r y s t a l t u f f . A g r a d a t i o n t o l a r g e r s i z e d fragments i n the t u f f s g o i n g u p s e c t i o n appears l o c a l l y . The t u f f s a r e massive t o t h i n l y bedded w i t h i n d i v i d u a l beds measuring up t o 10 cm. U n i t 7. Medium t o dark green a n d e s i t i c agglomerate and v o l c a n i c b r e c c i a w i t h i n t e r b e d d e d c h e r t and s h a l y a r g i l l i t e . U n i t 8. An a p h a n i t i c t o f i n e - g r a i n e d f e l s i c v o l c a n i c rock i s c o n t a i n e d as a l e n s e w i t h i n the a n d e s i t i c t u f f . P r e s e r v e d s t r u c t u r a l r e l a t i o n s a r e poor and t h e w r i t e r i s u n c e r t a i n whether t h i s u n i t r e p r e s e n t s a s m a l l , d i s c o n t i n u o u s e x t r u s i v e rock o r a c o n c o r d a n t hypabyssal i n t r u s i o n . T h i s f e l s i c r ock i s now w e l l f o l i a t e d . U n i t 9. A t h i n , 3 m wide, s e r p e n t i n i z e d p e r i d o t i t e s i l l l i e s w i t h i n t h e Permian s e c t i o n and i s r e p e a t e d by f o l d i n g . I t i s dark green t o g r e e n i s h - b l a c k and p a r t l y s h e a r e d . 182 The f o r g o i n g sequence forms t h e n o r t h e a s t e r n limb o f a r e g i o n a l s y n c l i n e t h a t t r e n d s n o r t h w e s t , i s i s o c l i n a l , and i n c l i n e d t o the s o u t h -west. The g e o l o g i c map f o r P i c k h a n d l e p r o p e r t y ( F i g u r e A l ) shows r e p e t i t i o n o f rock u n i t s and s t r u c t u r a l d a t a s u g g e s t t h a t numerous s m a l l e r s c a l e i s o c l i n a l f o l d s and s u b p a r a l l e l f a u l t s cause t h i s r e p e t i t i o n . P r i m a r y l a y e r i n g s t r i k e s 135°to 155° and d i p s 50° t o 75° t o the southwest. F o l i a t i o n s t r i k e s 115° t o 135° and d i p s 50° t o 70° t o the southwest. L i n e a t i o n s on the plane o f f o l i a t i o n i n c l u d e minor f o l d a x e s , e l o n g a t e d c h l o r i t e c l o t s , q u a r t z r o d s , and c r e n u l a t i o n s . Plunges a r e 15° t o 35° t o e i t h e r t h e s o u t h e a s t o r n o r t h w e s t . The b a s a l t i c a n d e s i t e f l o w s a r e l o c a l l y s c h i s t o s e and t h e most massive t u f f s a r e p o o r l y f o l i a t e d . Major sh e a r p l a n e s s t r i k e 125° and 135° and d i p 70° SW to v e r t i c a l . S l i c k e n s i d e s plunge 10° t o 30° t o the s o u t h e a s t . Three f a u l t s , two d e f i n e d and one i n t e r p r e t e d , t r e n d n o r t h w e s t e r l y a c r o s s the p r o p e r t y . These f a u l t s a ppear t o d i p s t e e p l y , but the type o f movement i s u n c e r t a i n . S t a t i o n Creek Formation i s c h a r a c t e r i z e d by numerous v e i n s and s t r i n g e r s o f q u a r t z , c a l c i t e , and e p i d o t e , which o c c u r a l o n g f r a c t u r e o r s h e a r p l a n e s o r p a r a l l e l t o f o l i a t i o n . Q u a r t z v e i n s and s t r i n g e r s , a s s o c i a t e d w i t h c o p p e r - i r o n s u l p h i d e s , g e n e r a l l y f o l l o w f r a c t u r e s and s h e a r s . S t r i n g e r s and v e i n s up t o 1 cm wide, and o f t e n f o l d e d , c o n t a i n c h a l c o p y r i t e and/or p y r i t e and o c c u r a t a s l i g h t a n g l e to f o l i a t i o n . M i n e r a l D e p o s i t s S u l p h i d e m i n e r a l s o c c u r r i n g on t h e p r o p e r t y , i n o r d e r o f abundance, a r e p y r i t e , c h a l c o p y r i t e , and p y r r h o t i t e . S u l p h i d e o c c u r r e n c e s i n c l u d e : (1) m i n e r a l i z e d zones, 15 t o 30 cm w i d e, v e i n s , 2 t o 5 cm w i d e, and seams up t o 1 cm wide, r u n n i n g p a r a l l e l to f o l i a t i o n o r a l o n g f r a c t u r e s and s h e a r s ; (2) s m a l l l e n s e s , 0.5 by 1 cm, and d i s s e m i n a t i o n s , i n t e r c o n n e c t e d by m i c r o v e i n l e t s ; and (3) p y r i t e o r p y r r h o t i t e and c h a l c o p y r i t e i n q u a r t z , 183 c a l c i t e , and e p i d o t e v e i n s , o c c u r r i n g i n d i v i d u a l l y o r i n s u b p a r a l l e l groups. V e i n s u l p h i d e s a r e s c a t t e r e d t h r o u g h o u t the p r o p e r t y , but are most abundant i n a l a y e r o f f o l d e d b a s a l t i c a n d e s i t e flows o v e r l a i n by c o a r s e -g r a i n e d a n d e s i t i c t u f f . The m i n e r a l i z e d h o r i z o n may be t r a c e d , d i s c o n t i n -u o u s l y , f o r 2 km a l o n g s t r i k e and 360 m a l o n g a p p a r e n t t h i c k n e s s . The northwest end o f t h e h o r i z o n i s f a u l t - b o u n d e d ; t h e s o u t h e a s t end i s c o v e r e d by overburden. The Camp Showings and Main Showings l i e w i t h i n the m i n e r a l i z e d h o r i z o n . The Camp Showings i n c l u d e : (1) 15 to 30 cm wide zones c o n t a i n i n g c h a l c o p y r i t e , p y r i t e , and minor m a l a c h i t e and a z u r i t e i n both t he flows and t u f f s . These zones s i t a l o n g s h e a r s e i t h e r p a r a l l e l t o o r a t an angle t o f o l i a t i o n and average t r e n d o f t h e zones i s 075° w i t h a 65° d i p to the s o u t h e a s t ; (2) c h a l c o p y r i t e and p y r i t e i n q u a r t z - c a l c i t e - e p i d o t e v e i n s p a r a l l e l to f o l i a t i o n i n t h e f l o w s ; (3) c h a l c o p y r i t e o r p y r i t e l e n s e s e l o n g a t e p a r a l l e l t o f o l i a t i o n i n the v o l c a n i c f l o w s ; and (4) d i s s e m i n a t e d c h a l c o -p y r i t e and p y r i t e i n c o a r s e - g r a i n e d a n d e s i t i c t u f f s . The Main Showing i s c h a l c o p y r i t e and p y r r h o t i t e i n q u a r t z - c a l c i t e v e i n s i n t u f f t h a t i s e x t e n s i v e l y r i d d l e d w i t h p e r v a s i v e and v e i n e p i d o t e . These s u l p h i d e -b e a r i n g v e i n s have had t h e i r t h i c k n e s s g r o s s l y e x a g g e r a t e d by p t y g m a t i c f o l d i n g . C h a l c o p y r i t e a l s o o c c u r s by i t s e l f i n v e i n s , 2 t o 4 cm wide, i n t h e Main Show a r e a . Small showings, o c c u r r i n g o u t s i d e the m i n e r a l i z e d h o r i z o n , i n c l u d e : (1) c h a l c o p y r i t e and p y r i t e i n q u a r t z v e i n s i n i n t e r b e d d e d t u f f and a r g i l l i t e ; (2) c h a l c o p y r i t e a l o n g s h e a r s i n c h e r t y a r g i l l i t e ; (3) c h a l c o p y r i t e i n q u a r t z - c a l c i t e v e i n s i n f r a c t u r e d l i m e s t o n e and c h e r t ; and (4) d i s s e m i n a t e d c h a l c o p y r i t e , p y r i t e , and ma g n e t i t e i n b r e c c i a t e d c o a r s e - g r a i n e d t u f f which had been i n f i l l e d w i t h q u a r t z - c a l c i t e v e i n s and s t r i n g e r s . 184 In summary, t h e r e a r e two d i s t i n c t types o f c o p p e r - i r o n s u l p h i d e o c c u r r e n c e s on the P i c k h a n d l e p r o p e r t y . One type i n c l u d e s d i s s e m i n a t e d and l e n s - s h a p e d l a y e r s o f s u l p h i d e s , and l e s s commonly, more c o n t i n u o u s but t h i n s u l p h i d e seams, w i t h i n the flows and t u f f s o f the m i n e r a l i z e d h o r i z o n . T h i s type i s s t r a t i f o r m and appears t o be s y n g e n e t i c o r e a r l y d i a g e n e t i c i n o r i g i n . The second type o f s u l p h i d e o c c u r r e n c e i n c l u d e s a l l t he v e i n s u l p h i d e s , which are e p i g e n e t i c . NICKEL-COPPER ASSOCIATED WITH ULTRAMAFIC INTRUSIONS We l l g r e e n P r o p e r t y  L o c a t i o n W e l l g r e e n Mine i s 3.2 km west o f t h e j u n c t i o n o f Q u i l l and N i c k e l C r e e k s . A g e o l o g i c map ( F i g u r e A2) a t a s c a l e o f 1:4800 c o v e r s an a r e a o f 3.8 square km w i t h the mine s i t u a t e d near the e a s t e r n boundary. H i s t o r y o f Development Claims s t a k e d on a n i c k e l - c o p p e r s u l p h i d e showing, d i s c o v e r e d i n June, 1952 by W.B. Green and a s s o c i a t e s , became known as the W e l l g r e e n p r o p e r t y . T h i s p r o p e r t y was o p t i o n e d by Hudson Bay E x p l o r a t i o n and Development Company L i m i t e d i n 1952 and s i n c e 1955 has been h e l d through a s u b s i d i a r y , Hudson-Yukon M i n i n g Company L i m i t e d , W h i t e h o r s e , Yukon T e r r i t o r y . Development on t h e p r o p e r t y d u r i n g t h e p e r i o d 1953 to 1956 i n c l u d e d s u r f a c e g e o l o g i c a l work, 4270 m o f underground w o r k i n g s , and 19,825 m o f s u r f a c e and underground diamond d r i l l i n g . Underground workings i n c l u d e d an a d i t , d r i v e n w e s t e r l y f o r 1220 m a t e l e v a t i o n 4250 f t . (1296 m), and c o n n e c t e d by winzes and r a i s e s t o v a r i o u s w o r k i n g l e v e l s a t 4470 f t . (1363 m), 4050 f t . (1235 m), and 3650 f t . (1113 m), t h e work i n d i c a t e d an e s t i m a t e d 749,845 tonnes o f o r e , c o n t a i n i n g 2.04 p e r c e n t n i c k e l , 1.42 p e r c e n t c o p p e r , 185 0.073 p e r c e n t c o b a l t , 0.157 g Au/tonne, 1.188 g P t / t o n n e , and 0.844 g Pd/tonne. The p r o p e r t y was i n a c t i v e from 1956 t o 1968 (due t o l i m i t e d tonnage and remote l o c a t i o n ) , but t h e c l a i m s were h e l d i n good s t a n d i n g . Re-e v a l u a t i o n o f t h e p r o p e r t y began i n 1968 when ground g e o p h y s i c a l s u r v e y s were conducted o v e r t h e main showing. These s u r v e y s o u t l i n e d s e v e r a l anomalous a r e a s , which prompted 762 m o f diamond d r i l l i n g i n 1969 t o i n v e s t i g a t e the p o s s i b i l i t y o f d i s s e m i n a t e d s u l p h i d e z o n e s . P r o d u c t i o n p l a n s were announced and p r o p e r t y development work s t a r t e d i n F e b r u a r y , 1970. The e x p l o r a t i o n a d i t was s l a s h e d to a l l o w f o r mine h a u l a g e , an i n t e r n a l s h a f t was sunk, and l a t e r a l openings d r i v e n i n p r e p a r a t i o n f o r s t o p i n g . A powerhouse and mine dry were b u i l t a t the p o r t a l and a m i l l and t o w n s i t e were c o n s t r u c t e d a t MP 1111 (KMP 1988) a l o n g the A l a s k a Highway. P r o d u c t i o n from the W e l l g r e e n p r o p e r t y began i n May 1972 at a r a t e o f about 362 tonnes/day. The mine sh u t down i n August 1973 due t o poor ground c o n d i t i o n s and l a c k o f c o n t i n u i t y o f the ore body. A t o t a l o f 192,248 tonnes o f ore were m i l l e d and t h e c o n c e n t r a t e s h i p p e d by road t o H a i n e s , A l a s k a f o r s h i p p i n g by deep sea v e s s e l t o Japen. The o p e r a t i n g summary i s p r e s e n t e d i n T a b l e A l . Geology The W e l l g r e e n p r o p e r t y i s u n d e r l a i n by Lower Permian s e d i m e n t a r y and v o l c a n i c l a s t i c r o c k s o f S t a t i o n Creek F o r m a t i o n , minor Hasen Creek s e d i m e n t a r y r o c k s , and t h e Upper T r i a s s i c N i k o l a i b a s a l t f l o w s . The map i s c e n t e r e d on the n o r t h w e s t e x t r e m i t y o f Q u i l l Creek g a b b r o - u l t r a m a f i c complex. T h i s complex l i e s w i t h i n t h e T r a n s i t i o n Zone o f S t a t i o n Creek Formation. S t a t i o n Creek v o l c a n i c l a s t i c r o c k s i n c l u d e an i n t e r b e d d e d m i x t u r e o f t h i n l y l a m i n a t e d v e r y f i n e - g r a i n e d t u f f , massive f i n e t o n e a r l y medium-186 TABLE A l . O p e r a t i n g Summary f o r the W e l l g r e e n Mine 1972 1973 Tonnes M i l l e d 114,256 77,992 Rate (tonnes/day) 362 427 Grade: N i c k e l (%) 2.05 2.49 Copper {%) 1.35 1.45 Pt M e t a l s (g/tonne) 2.03 2.03 Co (%) 0.073 0.073 1 A f t e r e i g h t months o f o p e r a t i o n each y e a r . 187 g r a i n e d t u f f , and l o c a l l y , massive v o l c a n i c b r e c c i a w i t h s u b a n g u l a r fragments measuring 5 t o 15 cm a c r o s s . Much o f the exposed S t a t i o n Creek s e c t i o n i s t h e T r a n s i t i o n Zone. Here, t h e t u f f i s v e r y f i n e - g r a i n e d and i n t e r b e d d e d s e d i m e n t a r y r o c k s a r e abundant and i n c l u d e grey t o g r e e n i s h - g r e y a r g i l l i t e and c h e r t y a r g i l l i t e , b l a c k s h a l e , s i l t s t o n e , and l i m y a r g i l l i t e . P a l e g r e y a r g i l l a c e o u s l i m e s t o n e i s minor. The a r g i l l i t e i s bedded and w e l l f r a c t u r e d , w i t h i r o n o x i d e s a l o n g f r a c t u r e s u r f a c e s . Hasen Creek Formation i s exposed i n the n o r t h e a s t c o r n e r o f the p r o p e r t y map. A p h a n i t i c s h a l y and c h e r t y a r g i l l i t e are i n t e r b e d d e d w i t h minor w h i t e l i m e s t o n e , massive grey s i l t s t o n e and greywacke, and g r e y - b l a c k p e b b l y c o n g l o m e r a t e . N i k o l a i Greenstone i s i n f a u l t c o n t a c t w i t h both the Q u i l l Creek complex and S t a t i o n Creek v o l c a n i c l a s t i c r o c k s i n the southwest c o r n e r o f W e l l g r e e n p r o p e r t y . The b a s a l t i s green t o r e d d i s h - p u r p l e , v e r y f i n e - g r a i n e d , and massive. B u f f - c o l o r e d l i m e s t o n e i s i n t e r s t r a t i f i e d l o c a l l y w i t h the f l o w s . Amygdules i n c l u d e c h l o r i t e , e p i d o t e , and c a l c i t e . Q u i l l Creek complex i s composed o f p e r i d o t i t e , d u n i t e , and minor gabbro. Dunite i s exposed o v e r a w i d t h o f 190 m and i s p a l e grey to g r e e n , cumulate t e x t u r e d , and t o t a l l y s e r p e n t i n i z e d . Dark green t o g r e e n i s h - b l a c k , s e r p e n t i n i z e d and u r a l i t i z e d p e r i d o t i t e i s exposed o v e r a w i d t h o f about 610 m. Gabbro i s 5 t o 40 m wide and i s exposed d i s c o n t i n u o u s l y a l o n g p a r t o f t h e base o f t h e u l t r a m a f i c s i l l . The d u n i t e appears to be a b a s a l u n i t o f l i m i t e d e x t e n t . Gabbro appears t o i n t r u d e a l o n g t h e base o f t h e p e r i d o t i t e near where i t extends beyond the d u n i t e . The p e r i d o t i t e c o n t a i n s small x e n o l i t h s o f b a s a l t i c a n d e s i t e t u f f h o r n f e l s e d t o a m i n e r a l assemblage o f pyroxene and p l a g i o c l a s e . H i g h l y i r r e g u l a r - s h a p e d "dykes" o f f i n e - g r a i n e d f e l s i t e o c c u r w i t h i n the p e r i d o t i t e . 188 C o n t a c t s o f t h e u l t r a m a f i t e are g e n e r a l l y s h e a r e d , but major f a u l t i n g i s i n d i c a t e d o n l y a l o n g t h e southwest c o n t a c t o f the d u n i t e . An i r r e g u l a r p a l e creme t o w h i t e a l t e r a t i o n zone, up t o 60 m wide, o c c u r s i n w a l l r o c k a d j a c e n t t o the- s e r p e n t i n i z e d s i l l . The a l t e r a t i o n i s q u a r t z - c a r b o n a t e + m a r i p o s i t e and i t s i n t e n s i t y d e c r e a s e s i r r e g u l a r l y away from the u l t r a m a f i t e . The Q u i l l Creek complex l i e s r o u g h l y p a r a l l e l to s t r a t i g r a p h y , a l t h o u g h l o c a l d i s c o r d a n c e s a r e p r e s e n t . P r i m a r y bedding p l a n e s i n t h e Permian c o u n t r y r o c k s v a r y from s t r i k e s o f 070° to 120° and d i p s o f 50°SE through 90° t o 50°SW. F o l i a t i o n i s g e n e r a l l y 105°/60-70°SW. V o l c a n i c l a s t i c and s e d i m e n t a r y r o c k s a r e s h e a r e d and w e l l f r a c t u r e d . N i k o l a i b a s a l t s a r e m a s s i v e , b u t c o n t a i n abundant d i s c o n t i n u o u s c h l o r i t i c s h e a r s . Q u i l l Creek complex s e p a r a t e s i n t o i r r e g u l a r s u b p a r a l l e l f i n g e r s a t i t s n o r t h w e s t e x t r e m i t y , as a r e s u l t o f f o l d i n g . The u l t r a m a f i t e i s i n t e n s e l y s h e a r e d and c h a r a c t e r i z e d by s h e a r planes s t r i k i n g d o m i n a h t l y e a s t - n o r t h e a s t to e a s t - s o u t h e a s t . S l i c k e n s i d e s g e n e r a l l y plunge i n a southwest d i r e c t i o n . M i n e r a l D e p o s i t s F i g u r e A2 shows t h r e e s u r f a c e showings (No. 1, 1%, and 2) on the W e l l g r e e n p r o p e r t y . Types o f s u l p h i d e m i n e r a l o c c u r r e n c e s i n c l u d e : (1) massive t o n e a r massive f i n e - g r a i n e d s u l p h i d e s , l o c a l l y , w i t h abundant m a g n e t i t e -No. 1 and 2; (2) b r e c c i a s u l p h i d e s w i t h rounded t o a n g u l a r i n c l u s i o n s o f v o l c a n i c t u f f , c h e r t y a r g i l l i t e , gabbro, and p e r i d o t i t e - No. 1; (3) n e t -t e x t u r e d s u l p h i d e s i n gabbro - No. 1 and 2; (4) h e a v i l y d i s s e m i n a t e d s u l p h i d e s i n gabbro- No. 1, \h, and 2; (5) weakly d i s s e m i n a t e d s u l p h i d e s i n p e r i d o t i t e - No. 1 and 1%; and (6) d i s s e m i n a t e d and s t r i n g e r s u l p h i d e s i n c h e r t y a r g i l l i t e and t u f f a d j a c e n t to the massive ore pods - No. 1. The exposed pods o f massive p y r r h o t i t e , c h a l c o p y r i t e , and p e n t l a n d i t e a r e a p p r o x i m a t e l y 2 m to 10 m wide by 3 t o 20 m l o n g . C o n t a c t s a r e s h a r p t o s h e a r e d l o c a l l y . These pods s i t a t t h e g a b b r o / c o u n t r y rock c o n t a c t o r 189 p e r i d o t i t e / c o u n t r y rock c o n t a c t . In g e n e r a l , the s u l p h i d e s change upwards from massive a t the gabbro base to n e t - t e x t u r e d i n gabbro t o d i s s e m i n a t e d i n p e r i d o t i t e . D i s s e m i n a t e d s u l p h i d e m i n e r a l s i n the p e r i d o t i t e are i n -t e r s t i t i a l and, where l o c a l l y abundant, approach a n e t - t e x t u r e d appearance. S u l p h i d e m i n e r a l s i n the W e l l g r e e n d e p o s i t s i n c l u d e ( i n r e l a t i v e o r d e r o f abundance): p y r r h o t i t e , p e n t l a n d i t e , and c h a l c o p y r i t e . P y r i t e i s a b s e n t . P y r r h o t i t e i s a l l o t r i o m o r p h i c g r a n u l a r and forms i r r e g u l a r l y shaped masses. P e n t l a n d i t e o c c u r s as f e a t h e r y e x s o l u t i o n flames i n p y r -r h o t i t e masses, as xenomorphic patches between p y r r h o t i t e g r a i n s ( r i m t e x t u r e ) , as small i r r e g u l a r l y shaped g r a i n s s c a t t e r e d a l o n g p y r r h o t i t e g r a i n b o u n d a r i e s ( a l s o r i m t e x t u r e ) , and as c o a r s e w e l l d e f i n e d g r a i n s showing o c t a h e d r a l c l e a v a g e . C h a l c o p y r i t e o c c u r s as small i r r e g u l a r l y shaped b l e b s i n p y r r h o t i t e masses ( u s u a l l y a t g r a i n b o u n d a r i e s ) , as patches a l o n g the boundary between p y r r h o t i t e and s i l i c a t e s , and as tongues and s c a t t e r e d masses a l o n g f r a c t u r e s w i t h i n the s i l i c a t e s . C e r t a i n t e x t u r e s o f the s u l p h i d e m i n e r a l s a r e i n d i c a t i v e o f a mag-m a t i c o r i g i n as an i m m i s c i b l e s u l p h i d e m e l t . P y r r h o t i t e - c h a l c o p y r i t e patches a r e i n t e r c u m u l u s to o l i v i n e c r y s t a l s i n p e r i d o t i t e . They a l s o o c c u r w i t h o l i v i n e i n p o i k i l i t i c c l i n o p y r o x e n e , Small o v a l - s h a p e d b l e b s o f s u l p h i d e s s i t a l o n g c l e a v a g e t r a c e s i n c l i n o p y r o x e n e . O l i v i n e c r y s -t a l s and o t h e r s i l i c a t e g r a i n s a r e i n c o r p o r a t e d i n t o masses o f p y r r h o t i t e . N e t - t e x t u r e s u l p h i d e s i n gabbro are a l s o i n d i c a t i v e o f a magmatic o r i g i n . Numerous t e x t u r e s o f the d i f f e r e n t types o f s u l p h i d e o c c u r r e n c e show d e f o r m a t i o n and/or r e m o b i l i z a t i o n . F o l i a t i o n o f the s u l p h i d e masses i s s l i g h t to w e l l d e v e l o p e d . T h i s f o l i a t i o n may be due to a l t e r n a t i n g bands o f p y r r h o t i t e - p e n t l a n d i t e and c h a l c o p y r i t e - s i 1 i c a t e s . The s i l i c a t e i n c l u s i o n s are s c a t t e r e d i n t o a g g r e g a t e s o f rounded p a r t i c l e s t h a t are 190 s t r u n g out and a l i g n e d s u b p a r a l l e l t o each o t h e r . These s i l i c a t e a g g r e g a t e s a r e o f t e n augen-shaped and boudinaged w i t h f o l i a t e d s u l p h i d e m i n e r a l s wrapping around them. L o c a l l y the a g g r e g a t e s are r o l l e d . Some p o l i s h e d s e c t i o n s show the s i l i c a t e s t o be s t r u n g o u t , f o l d e d , s h e a r e d , broken, and r o l l e d . Most s i l i c a t e i n c l u s i o n s a r e m o t t l e d around t h e i r b o r d e r s . C h a l c o p y r i t e i n t r u d e s s i l i c a t e masses as v e i n l e t s , s t r i n g e r s , and i r r e g u l a r patches a l o n g f r a c t u r e s . These v e i n l e t s s t a r t i n the p y r r h o t i t e mass and c r o s s c u t both i t and t h e s i l i c a t e s . P y r r h o t i t e forms i t s own v e i n s a l t h o u g h they a r e not as common as those o f c h a l c o p y r i t e . C h a l c o p y r i t e and* p y r r h o t i t e r a r e l y o c c u r t o g e t h e r i n the same v e i n l e t . These s t r i n g e r s a r e g e n e r a l l y p e r p e n d i c u l a r t o f o l i a t i o n and may o r may n o t c o n t a i n wisps o f s e r p e n t i n e and c h l o r i t e a r r a n g e d p a r a l l e l t o the v e i n l e t w a l l s . One p o l i s h e d s e c t i o n shows a t e n s i o n gash o f s e r p e n t i n e and c h l o r i t e w i t h accompanying s u l p h i d e g r a i n s . Summary o f Underground G e o l o g i c I n f o r m a t i o n Three main rock types were e n c o u n t e r e d underground: c h e r t y . a r g i l l i t e , gabbro, and p e r i d o t i t e . The c h e r t y a r g i l l i t e was termed q u a r t z i t e i n the mine and i s i n t e r b e d d e d w i t h s h a l e , l i m e s t o n e , and greywacke. The gabbro i s an i r r e g u l a r t a b u l a r body r a n g i n g from 0 t o 46 m t h i c k , w i t h an average t h i c k n e s s o f 7 t o 9 m. The c o n t a c t i s s t r o n g l y d i s c o r d a n t i n some l o c a l -i t i e s o f t h e mine where i t c u t s a c r o s s bedding i n the a r g i l l i t e and l i m e s t o n e . The f o o t w a l l c o n t a c t o f t h e u l t r a m a f i t e i s v e r y i r r e g u l a r and r o l l s from a s t e e p s o u t h w e s t e r l y d i p t o h o r i z o n t a l and then back to s t e e p a g a i n . C o n t a c t r e l a t i o n s a r e not c l e a r i n many a r e a s . The g a b b r o / c h e r t y a r g i l l i t e c o n t a c t has been d e s c r i b e d as s h a r p and a p p a r e n t l y n o t f a u l t e d . The g a b b r o / p e r i d o t i t e c o n t a c t i s , on the o t h e r hand, g e n e r a l l y f a u l t e d and t h e nearby p e r i d o t i t e i n t e n s e l y s h e a r e d . 191 Massive s u l p h i d e b o d i e s i n the W e l l g r e e n Mine are found i n c o n t a c t w i t h c h e r t y a r g i l l i t e , gabbro, o r p e r i d o t i t e . The f o o t w a l l c o n t a c t w i t h t h e a r g i l l i t e i s s h a r p and shows a 5 cm to 15 cm b l a c k h o r n f e l s e d b o r d e r . The m i n e r a l c o n s t i t u e n t s i n t h i s b o r d e r are h o r n b l e n d e , minor pyroxene, and p l a g i o c l a s e . A r g i l l i t e b e d d i n g i s t r u n c a t e d by s u l p h i d e pods i n some p l a c e s and l o c a l l y , t he ore t a i l s out i n t o t h e w a l l r o c k . C h a l c o -p y r i t e w i t h a l e s s e r amount o f p y r r h o t i t e o c c u r a l o n g f r a c t u r e s and as b l e b b y s u l p h i d e s i n t h e b l a c k h o r n f e l s . The gabbro/massive ore c o n t a c t s a r e v a r i a b l e from f a u l t e d and s h a r p i n some p l a c e s t o g r a d a t i o n a l i n o t h e r l o c a l i t i e s . Small b o d i e s o f massive ore are e n c l o s e d w i t h i n the gabbro and s t r e a k y s u l p h i d e b l e b s or "amoeba" are o f t e n p r e s e n t a t t h e base o f t h e gabbro. S h e a r i n g and f a u l t i n g have c o m p l i c a t e d the underground g e o l o g y . Two main d i r e c t i o n s a r e e a s t - w e s t s h e a r i n g w i t h i n the p e r i d o t i t e p a r a l l e l t o c o n t a c t s and northwest f a u l t i n g which o f f s e t s the o r e . Only one f a u l t , which c u t s t h e i n t r u s i v e c o n t a c t , i s r e c o g n i z a b l e from l e v e l to l e v e l . I t s t r i k e s n o r t h w e s t e r l y and d i p s t o t h e southwest, d i s p l a c i n g the c o n t a c t about 30 m l e f t l a t e r a l l y . S l i c k e n s i d e s plunge a t moderate a n g l e s t o the n o r t h and west, i n d i c a t i n g the movement t o be s u b h o r i z o n t a l . F a u l t gouge a s s o c i a t e d w i t h t h i s f a u l t i s as much as 0.6 m where c o u n t r y rock i s i n c o n t a c t w i t h gabbro o r p e r i d o t i t e . The gouge narrows to l e s s than 10 cm where massive s u l p h i d e pods a r e p r e s e n t . The ore b o d i e s and hangingwall gabbro and p e r i d o t i t e have been i n t e n s e l y s h e a r e d and f r a c t u r e d i n s e v e r a l d i r e c t i o n s and ground c o n d i t i o n s i n t h e mine were g e n e r a l l y poor. Ore w i d t h s v a r y r a p i d l y i n t h e mine from 3 t o 18 m, but even 6 m wide ore i s uncommon. The ore i s e r r a t i c and d i s c o n t i n u o u s w i t h the most 192 s i g n i f i c a n t zones o c c u r r i n g where t h e f o o t w a l l c o n t a c t f l a t t e n s . These c o n t a c t " r o l l s " plunge a t a moderate a n g l e t o the west. Ore/wall rock c o n t a c t s a r e v a r i a b l e from sharp t o g r a d a t i o n a l . C o n t a c t s a r e c o n t r o l l e d l o c a l l y by j o i n t s , f a u l t s , and b e d d i n g . F a u l t s and f r a c t u r e s most f r e q u e n t l y d e f i n i n g t h e c o n t a c t are s u b p a r a l l e l t o the u l t r a m a f i t e / c o u n t r y rock c o n t a c t . F a u l t i n g i s f r e q u e n t on the hangingwall w i t h f a u l t s o c c u r r i n g j u s t i n s i d e t h e gabbro. Where t h e s e f a u l t s d i v e r g e c o n s i d e r a b l y from t h e g a b b r o / c o u n t r y rock c o n t a c t the ore g e n e r a l l y recedes t o t h e l a t t e r . Many f o o t w a l l c o n t a c t s c o i n c i d e w i t h b e d d i n g i n the a r g i l l i t e . Ore d i s t r i b u t i o n i n t h e mine i s r e l a t e d to two s t r u c t u r a l f e a t u r e s . The w e s t e r l y p l u n g i n g t h i c k e n i n g a x i s o f gabbro c o r r e s p o n d s t o the lower l i m i t o f o r e . A l s o the n o r t h w e s t e r l y s t r i k i n g f a u l t c o i n c i d e s w i t h wide ore i n t e r s e c t i o n s . The s u l p h i d e ore shows d e f o r m a t i o n t e x t u r e s and appears to have been o f f s e t and s t r u n g out a l o n g the f a u l t . I n t e r n a l f e a t u r e s i n , t h e massive ore pods i n c l u d e : (1) a n g u l a r t o rounded x e n o l i t h s o f a r g i l l i t e , gabbro, and p e r i d o t i t e ; (2) f o l i a t i o n ; and (3) p o s t - o r e v e i n i n g . The m a j o r i t y o f a r g i l l i t e and p e r i d o t i t e xeno-l i t h s a r e s u b a n g u l a r , whereas many o f t h e gabbro i n c l u s i o n s a r e rounded and o f t e n vague i n o u t l i n e . P o s t - o r e c a r b o n a t e v e i n s c u t both t h e a r g i l l i t e and s u l p h i d e s . Pure c h a l c o p y r i t e v e i n s , i n t u r n , c u t the c a r b o n a t e v e i n s and c h a l c o p y r i t e t y p i c a l l y s u r r o u n d s w a l l r o c k x e n o l i t h s i n the o r e . Arch Creek P r o p e r t y L o c a t i o n The p r o p e r t y i s l o c a t e d n o r t h w e s t from W e l l g r e e n Mine and i s a c c e s s -i b l e by a 3.5 km Cat road l e a d i n g from t h e mine. F i g u r e A3 i s a g e o l o g i c map o f most o f t h e c l a i m group. 193 H i s t o r y o f Development P r e v i o u s work on t h e p r o p e r t y i n c l u d e s t r e n c h i n g , g r i d d i n g , magnetic and EM g e o p h y s i c a l s u r v e y s , g e o c h e m i s t r y o f rock c h i p samples, and d e t a i l e d g e o l o g i c mapping. Most o f t h i s work was c a r r i e d out by N i c k e l S y n d i c a t e i n 1972. Geology The p r o p e r t y i s u n d e r l a i n by t h e S t a t i o n Creek T r a n s i t i o n Zone, c o n s i s t i n g o f i n t e r b e d d e d b a s a l t i c a n d e s i t e t u f f , minor v o l c a n i c b r e c c i a , and t h i n s e d i m e n t a r y l a y e r s . T r i a s s i c b a s a l t i c f l o ws a r e p o o r l y exposed and i n f a u l t c o n t a c t w i t h the v o l c a n i c l a s t i c r o c k s i n the s o u t h e r n p a r t o f t h e map a r e a . A small p e r i d o t i t i c body o c c u r s i n the c e n t r a l p a r t o f the a r e a . S t a t i o n Creek v o l c a n i c l a s t i c r o c k s a r e medium-green t o g r e y i s h - g r e e n and massive t o t h i n l y bedded. I n t e r s t r a t i f i e d s e d i m e n t a r y r o c k s i n c l u d e s i l t s t o n e , s h a l e , l i m e s t o n e and c h e r t y and l i m y a r g i l l i t e . A r g i l l i t e i s p a l e g r e y and t h i n l y bedded ( s e v e r a l m i l l i m e t e r s t o c e n t i m e t e r s ) . Banded c h e r t and c h e r t y a r g i l l i t e o c c u r a l o n g t h e n o r t h c o n t a c t o f t h e u l t r a m a f i t e and are s t r o n g l y f r a c t u r e d . Layers o f s h a l e are dark grey to b l a c k and u s u a l l y t h i n , measuring about 10 to 30 cm t h i c k . The s h a l e becomes s l a t y n ear c o n t a c t s w i t h t h e u l t r a m a f i t e . The Arch Creek complex i s about 900 m by 100 m and c o n s i s t s o f p e r i d o t i t e w i t h a t h i n , 0.6 t o 1 m w i de, d i s c o n t i n u o u s o l i v i n e gabbro b o r d e r phase a t the base. The complex has s u f f e r e d s e r p e n t i n i z a t i o n and u r a l i t i z a t i o n . Small f e l s i t e dykes, l e s s than 1 m w i de, o c c u r w i t h i n the Arch Creek p e r i d o t i t e . P r i m a r y bedding p l a n e s i n the t u f f a c e o u s and s e d i m e n t a r y r o c k s s t r i k e n o r t h e a s t t o e a s t - n o r t h e a s t and d i p 45° SE through 90° t o 65°NW. F o l i a t i o n i s v a r i a b l e from 045°/75° SE t o 070°/90° to 149°/74°SW. A minor f o l d i n 194 p e r i d o t i t e has an a x i a l plane o f 056°/90° and an a x i a l plunge o f 14°/236°. T h i s a x i a l t r e n d i s s i m i l a r t o t h a t measured f o r t h e l a r g e s y n c l i n e to the n o r t h e a s t . F i n e - g r a i n e d t u f f s and c h e r t y a r g i l l i t e a r e e x t e n s i v e l y f r a c t u r e d and a l l rocks have been s h e a r e d . A major f a u l t a l o n g the so u t h e r n p a r t o f t h e p r o p e r t y map appears to d i p s t e e p l y t o the s o u t h . Arch Creek complex i s d i r e c t l y on s t r i k e w i t h the l a r g e r Q u i l l Creek complex t o t h e s o u t h e a s t . T h i s s t r u c t u r a l r e l a t i o n t o g e t h e r w i t h s i m i l a r -i t i e s i n m i n e r a l c o n s t i t u e n t s and rock t y p e s , s u g g e s t t h a t t h e Arch Creek complex may be p a r t o f t h e l a r g e r Q u i l l Creek body, dismembered by f o l d i n g and/or f a u l t i n g and e r o s i o n . M i n e r a l D e p o s i t s N i c k e l - c o p p e r s u l p h i d e d e p o s i t s a r e s i m i l a r t o thos e a t W e l l g r e e n , but on a much s m a l l e r s c a l e . The main Showing c o n s i s t s o f o l i v i n e gabbro at the base o f t h e p e r i d o t i t e and w i t h f r a c t u r e d c h e r t y a r g i l l i t e on e i t h e r s i d e o f t h e complex. The s e r p e n t i n i z e d p e r i d o t i t e c o n t a i n s d i s -s e m i n a t e d , i n t e r s t i t i a l c h a l c o p y r i t e and p y r r h o t i t e . O l i v i n e gabbro i s up t o a meter wide and c o n t a i n s h e a v i l y d i s s e m i n a t e d s u l p h i d e s . An i r r e g u l a r d i s c o n t i n u o u s pod o f massive o r e , about 1 m wide, o c c u r s a t t h e o l i v i n e g a b b r o / c h e r t y a r g i l l i t e c o n t a c t . Maximum grades i n the massive ore a r e 3 p e r c e n t n i c k e l and 1 p e r c e n t copper. S t r i n g e r s u l p h i d e s o c c u r as f r a c t u r e f i l l i n g s i n t h e c h e r t y a r g i l l i t e a d j a c e n t t o the ore pod. Arch Creek No. 2 showing i s s i m i l a r t o the main one, e x c e p t t h a t a ve r y s m a l l pod o f massive ore i s i n f a u l t c o n t a c t w i t h p e r i d o t i t e and o l i v i n e gabbro i s a b s e n t . T e x t u r e s i n the Arch Creek s u l p h i d e o c c u r r e n c e s are s i m i l a r t o those i n t h e W e l l g r e e n o r e . 195 L i n d a Creek P r o p e r t y  L o c a t i o n L i n d a Creek p r o p e r t y i s s i t u a t e d a p p r o x i m a t e l y 3.5 km e a s t o f W e l l -green Mine. The p r o p e r t y map s t r a d d l e s L i n d a Creek s o u t h e a s t o f i t s j u n c t i o n w i t h Q u i l l Creek ( F i g u r e A4). H i s t o r y o f Development P r e v i o u s work on L i n d a Creek p r o p e r t y o c c u r r e d between 1967 and 1972. Newmont M i n i n g C o r p o r a t i o n L i m i t e d , Vancouver, c a r r i e d out a geochemical s u r v e y and a i r b o r n e magnetic s u r v e y on t h e c l a i m s i n 1967 and p r o s p e c t i n g and b u l l d o z e r t r e n c h i n g was c o n d u c t e d i n the f a l l o f 1969 by P. V e r s l u c e and A s s o c i a t e s . N i c k e l S y n d i c a t e i n v e s t i g a t e d t h e p r o p e r t y i n 1972. G r i d d i n g , d e t a i l e d p r o s p e c t i n g , and mapping were completed d u r i n g August, 1972 and g e o p h y s i c a l s u r v e y s were conducted l a t e r t h a t f a l l . Geology The p r o p e r t y map c o v e r s an a r e a o f poor exposure. Lower Permian v o l c a n i c l a s t i c and s e d i m e n t a r y r o c k s o f the T r a n s i t i o n Zone dominate the a r e a t o t h e s o u t h , whereas p e r i d o t i t e o c c u p i e s the n o r t h e r n p a r t o f t h e map s h e e t . V o l c a n i c l a s t i c r o c k s a r e medium t o dark green, f i n e - g r a i n e d b a s a l t i c a n d e s i t e t u f f s and minor aggl o m e r a t e . The r o c k s a r e w e l l f r a c t u r e d and s h e a r e d l o c a l l y . I n t e r b e d d e d s e d i m e n t a r y r o c k s i n c l u d e p a l e grey to grey-b l a c k s h a l e , c h e r t y a r g i l l i t e , greywacke, s i l t s t o n e , and minor l i m e s t o n e . C h e r t y a r g i l l i t e i s s e v e r e l y f r a c t u r e d and l o c a l l y r u s t y w i t h p y r i t e and c h a l c o p y r i t e as f r a c t u r e f i l l i n g s . L a m i n a t i o n s w i t h i n bedded a r g i l l i t e a r e 2 t o 5 mm t h i c k . The b l a c k s h a l e i s p y r i t i c and has a f a i r l y w e l l d e v e l o p e d s l a t y c l e a v a g e i n some a r e a s . The s e d i m e n t a r y u n i t s t e n d t o p i n c h out l e n g t h w i s e and v a r y i n t h i c k n e s s from 10 to 50 m. The u l t r a m a f i t e i s p o o r l y exposed, but appears to be d o m i n a n t l y 196 s e r p e n t i n i z e d p e r i d o t i t e . I t i s dark green t o g r e e n i s h - b l a c k , s h e a r e d , and f o l i a t e d . D i s s e m i n a t e d i n t e r s t i t i a l s u l p h i d e s o c c u r w i t h i n the p e r i d o t i t e . X e n o l i t h s o f v o l c a n i c l a s t i c m a t e r i a l , h o r n f e l s e d to pyroxene and p l a g i o c l a s e , o c c u r w i t h i n p e r i d o t i t e and v a r y i n s i z e from 1.5 m by 1 m to 300 m by 100 m. O l i v i n e gabbro appears t o i n t r u d e t u f f a c e o u s w a l l r o c k near t h e base o f t h e p e r i d o t i t e . These gabbro b o d i e s are up t o 9 m wide and a r e e l o n g a t e r o u g h l y p a r a l l e l t o t h e u l t r a m a f i t e c o n t a c t . They may r e p r e s e n t o f f s h o o t s from an o l i v i n e gabbro b o r d e r phase s i m i l a r t o the one found on A r c h Creek p r o p e r t y . P r i m a r y b e d d i n g w i t h i n t h e t u f f a c e o u s and s e d i m e n t a r y l a y e r s s t r i k e s d o m i n a n t l y e a s t - n o r t h e a s t and d i p s about 55°SE. V e r t i c a l f o l i a t i o n p l a n e s s t r i k e n o r t h e a s t t o e a s t - w e s t . A l l o t h e r f o l i a t i o n s s t r i k e 070° t o 110° and d i p 45° t o 70° e i t h e r t o the s o u t h e a s t o r southwest. M i n e r a l D e p o s i t s S u l p h i d e s o c c u r r i n g i n t u f f a c e o u s r o c k s and s h a l e s and a r g i l l i t e s o f the T r a n s i t i o n Zone i n c l u d e s p a r s e l y d i s s e m i n a t e d p y r i t e and c h a l c o p y r i t e and/or p y r i t e i n t i n y s t r i n g e r s a l o n g f r a c t u r e s and s h e a r s . N i c k e l - c o p p e r s u l p h i d e s a r e a s s o c i a t e d w i t h a l l r o c k s o f t h e Q u i l l Creek complex. Weakly d i s s e m i n a t e d c h a l c o p y r i t e and p y r r h o t i t e o c c u r as i n t e r s t i t i a l " b l e b s " i n t h e s e r p e n t i n i z e d p e r i d o t i t e . H e a v i l y d i s s e m i n a t e d s u l p h i d e s a r e found i n t h e o l i v i n e gabbro b o d i e s and a s m a l l i r r e g u l a r pod o f massive ore o c c u r s a t t h e g a b b r o / t u f f c o n t a c t a t the Main showing. T h i s showing i s i n a c o m p l i c a t e d , f o l i a t e d m i x t u r e o f a l t e r e d t u f f , o l i v i n e gabbro which c u t s t h e t u f f , and p e r i d o t i t e . E r o s i o n appears to have c u t through the base o f t h e p e r i d o t i t i c s i l l , l e a v i n g an a p p a r e n t l a r g e i n c l u s i o n o f t u f f a c e o u s w a l l r o c k s u r r o u n d e d by p e r i d o t i t e . The 197 o l i v i n e gabbro i s e l o n g a t e p a r a l l e l t o the p e r i d o t i t e body and may r e p r e s e n t an i n t r u s i v e o f f s h o o t from t h e b o r d e r zone. Two r u s t y m i n e r a l i z e d zones a r e 2 m t o 1 m wide, r e s p e c t i v e l y . The 1 m wide zone i s about 10 m l o n g and has a s m a l l pod o f massive s u l p h i d e ore a t one end. Maximum as s a y v a l u e s i n the ore pod are 3.6 p e r c e n t n i c k e l and 1.85 p e r c e n t copper, but c o n c e n t r a t i o n s v a r y c o n s i d e r a b l y o v e r a s h o r t d i s t a n c e . H e a v i l y d i s s e m i n a t e d to n e a r l y n e t - t e x t u r e d s u l p h i d e s o c c u r w i t h i n the o l i v i n e gabbro. Minor s t r i n g e r s o f c h a l c o p y r i t e and p y r r h o t i t e o c c u r as f r a c t u r e f i l l i n g s i n t h e s u r r o u n d i n g v o l c a n i c t u f f . C analask P r o p e r t y  L o c a t i o n Canalask p r o p e r t y l i e s on both s i d e s o f the White R i v e r ( F i g u r e A5) and i s a p p r o x i m a t e l y 5 km s o u t h - s o u t h w e s t o f K o i d e r n a t MP 1167 (KMP 1878) on t h e A l a s k a Highway. The Canalask a d i t i s about 76 km n o r t h w e s t o f W e l l g r e e n Mine. H i s t o r y o f Development P r o s p e c t o r s Airways L i m i t e d d i s c o v e r e d n i c k e l - c o p p e r s u l p h i d e showings on the White R i v e r i n 1952. A t o t a l o f 1615 m o f s u r f a c e d r i l l i n g was c o n d u c t e d between 1952 and 1943 and i n 1954 the p r o p e r t y was a c q u i r e d by Canalask N i c k e l Mines L i m i t e d . The company conduct e d 2678 m o f s u r f a c e d r i l l i n g , 518 m o f underground d r i f t i n g , and 457 m o f underground d r i l l i n g between 1954 and 1958. Reserves o f 515,105 tonnes a t 1.68 p e r c e n t n i c k e l were r e p o r t e d . P r o p e r t y work was suspended i n 1958 and t h e c l a i m s a l l o w e d to l a p s e i n 1964. P. V e r s l u c e and a s s o c i a t e s r e s t a k e d the c l a i m s t h a t same y e a r a l o n g w i t h a d d i t i o n a l c l a i m s on the west bank o f White R i v e r . B l a s t i n g and b u l l d o z e r t r e n c h i n g by P. V e r s l u c e and a s s o c i a t e s i n 1966 uncovered s e v e r a l new showings. These m i n e r a l i z e d zones were i n v e s t i -gated i n 1967 and 1968 by a c o n s o r t i u m o f companies under o p t i o n from 198 P. V e r s l u c e . The c o n s o r t i u m c a r r i e d out 400 m o f s u r f a c e d r i l l i n g p l u s g e o p h y s i c a l s u r v e y s and b u l l d o z e r t r e n c h i n g i n 1967. R e h a b i l i t a t i o n o f t h e underground workings began i n the s p r i n g o f 1968 and was f o l l o w e d by 371 m o f underground d r i l l i n g . T h i s d r i l l i n g c o n f i r m e d the presence o f s u l p h i d e m i n e r a l i z a t i o n west o f t h e White R i v e r f a u l t , but n i c k e l and c o p p e r v a l u e s proved n e g l i g i b l e . The o p t i o n agreement was t e r m i n a t e d i n t h e f a l l o f 1968. N i c k e l S y n d i c a t e resumed work on t h e p r o p e r t y i n 1972 under o p t i o n agreement w i t h P. V e r s l u c e and a s s o c i a t e s . F i e l d work i n c l u d e d both d e t a i l e d magnetometer and EM s u r v e y s and g e o l o g i c mapping. Another group o f c l a i m s was s t a k e d i n May, 1973 and a t o t a l o f 610 m o f diamond d r i l l i n g was completed t h a t same y e a r t o t e s t magnetic anomalies r e l a t e d t o the p e r i d o t i t e . Geology The p r o p e r t y i s u n d e r l a i n by Lower Permian v o l c a n i c l a s t i c r o c k s o f S t a t i o n Creek F o r m a t i o n , t u f f a c e o u s and s e d i m e n t a r y r o c k s o f t h e T r a n s i t i o n Zone, s e d i m e n t a r y u n i t s o f Hasen Creek F o r m a t i o n , and Upper T r i a s s i c b a s a l t i c f l o w s o f t h e N i k o l a i Greenstone. An u l t r a m a f i c complex l i e s w i t h i n the T r a n s i t i o n Zone. The most abundant rock type on the p r o p e r t y i s green to g r e e n i s h -grey b a s a l t i c a n d e s i t e t u f f , v a r y i n g from f i n e - to medium-grained and massive to p o o r l y bedded. A l e s s e r amount o f l a p i l l i t u f f and v o l c a n i c b r e c c i a w i t h s u b a n g u l a r fragments a r e a s s o c i a t e d w i t h the t u f f . Minor s u l p h i d e s , namely, p y r i t e , c h a l c o p y r i t e , and p y r r h o t i t e , o c c u r as s p a r s e d i s s e m i n a -t i o n s and i n t i n y v e i n l e t s w i t h i n f r a c t u r e d v o l c a n i c l a s t i c r o c k s . I n t e r b e d d e d s e d i m e n t a r y r o c k s o f t h e T r a n s i t i o n Zone are m o s t l y t h i n l y l a m i n a t e d grey c h e r t y a r g i l l i t e and g r e y - b l a c k c h e r t w i t h l e s s e r 199 amounts o f s h a l e , s i l t s t o n e , and a r g i l l a c e o u s l i m e s t o n e . Bands o f d i s -s eminated p y r i t e o c c u r w i t h i n the c h e r t y a r g i l l i t e and s t r i n g e r c h a l c o p y r i t e and p y r i t e and/or p y r r h o t i t e are found a l o n g f r a c t u r e s i n l i m y r o c k s . Hasen Creek s e d i m e n t a r y r o c k s a r e exposed i n the south and west p a r t s o f t h e map a r e a . They i n c l u d e l a m i n a t e d t o near massive a r g i l l i t e and c h e r t y a r g i l l i t e , l i m e s t o n e , s h a l e , and pebbly c o n g l o m e r a t e . The a r g i l l i t e i s p a l e g r e y , b a d l y f r a c t u r e d , and l o c a l l y c o n t a i n s minor p y r i t e and c h a l c o p y r i t e a l o n g f r a c t u r e s u r f a c e s . The l i m e s t o n e i s g r e y - w h i t e and a r g i l l a c e o u s . P a l e brown to reddish-brown conglomerate c o n t a i n s subrounded p e b b l e s o f c h e r t . Minor greywacke i s i n t e r b e d d e d w i t h t h i s p e b b l y u n i t . N i k o l a i Greenstone i s r e s t r i c t e d t o e x p o s u r e s a l o n g M i l e s Ridge on the west s i d e o f White R i v e r . T h i s v o l c a n i c rock i s r e d d i s h - p u r p l e , v e r y f i n e - g r a i n e d , and a m y g d a l o i d a l w i t h c h l o r i t e , c a l c i t e , and e p i d o t e . The flows are l a r g e l y h e m a t i t i c . " D u n i t e forms the main exposed p a r t o f t h e White R i v e r complex. I t i s exposed as a g r e y i s h - w h i t e s i n u o u s body a l o n g M i l e s Ridge. The d u n i t e i s t o t a l l y s e r p e n t i n i z e d , w e l l f o l i a t e d , and s h e a r e d . I t s c o n t a c t s are l a r g e l y f a u l t e d . M a g n e t i t e s t r i n g e r s and s e r p e n t i n e - m a g n e t i t e v e i n l e t s o c c u r p a r a l l e l to f o l i a t i o n i n the d u n i t e . The complex i s p o o r l y exposed on t h e e a s t s i d e o f White R i v e r , but d u n i t e , gabbro, p e r i d o t i t e , and l o c a l o l i v i n e gabbro are d i s t i n g u i s h a b l e . P e r i d o t i t e i s medium-grained, p o o r l y f o l i a t e d , and p a r t l y s e r p e n t i n i z e d . The p e r i d o t i t e and d u n i t e show cumulate t e x t u r e d o l i v i n e . Gabbro o c c u r s south o f the d u n i t e and m i n e r a l o g i c a l l y appears t o b e l o n g t o the Upper T r i a s s i c Maple Creek gabbros. I t i s medium-grained, m a s s i v e , and c o n s i s t s o f pyroxene and p l a g i o c l a s e . O l i v i n e gabbro o c c u r s i n a t r e n c h t h a t c u t s the n o r t h e r n p e r i d o t i t e c o n t a c t . 200 I t appears t o form a b o r d e r phase a t the base o f the p e r i d o t i t e . Weakly d i s s e m i n a t e d c h a l c o p y r i t e and p y r r h o t i t e i n the p e r i d o t i t e become h e a v i l y d i s s e m i n a t e d t o n e t - t e x t u r e d i n the o l i v i n e gabbro and near massive a t the base o f t h e o l i v i n e gabbro. White R i v e r complex l i e s a l o n g the e a s t s i d e o f a n o r t h w e s t e r l y p l u n g i n g s y n c l i n e . Conspicuous p r i m a r y bedding p l a n e s i n both the t u f f s and s e d i m e n t a r y r o c k s are s c a r s e , but appear t o v a r y from 075°/60°SE to 105°/40°NE. The dominant f o l i a t i o n d i r e c t i o n i s e a s t - w e s t to s o u t h e a s t w i t h moderate d i p s t o the s o u t h and southwest, and l e s s commonly t o the n o r t h and n o r t h e a s t . The u l t r a m a f i t e i s d i s c o r d a n t w i t h i n the p r o p e r t y area and d i p s s t e e p l y to the s o u t h . F o l i a t i o n w i t h i n the White R i v e r complex i s g e n e r a l l y 125°/65°SW and minor f o l d s o c c u r w i t h a x i a l p l a n e s p a r a l l e l t o t h i s f o l i a t i o n . C o n t a c t s between rock types w i t h i n the complex a r e f a u l t e d and much o f t h e c o n t a c t w i t h w a l l r o c k i s f a u l t e d o r a t l e a s t s h e a r e d . F a u l t i n g o f the u l t r a m a f i t e b o r d e r s i s more p r e v a l e n t a l o n g M i l e s Ridge. Country r o c k s n o r t h o f the complex and on the e a s t s i d e o f White R i v e r are i n t e n s e l y f r a c t u r e d and s h e a r e d . M i n e r a l D e p o s i t s More than one t y p e o f s u l p h i d e o c c u r r e n c e i s found i n the Canalask p r o p e r t y . S u r f a c e showings are l o c a t e d w i t h i n 180 m n o r t h o f t h e White R i v e r complex f o o t w a l l c o n t a c t on the e a s t s i d e o f White R i v e r . M i n e r a l d e p o s i t s i n c l u d e : (1) d i s s e m i n a t e d c h a l c o p y r i t e and p y r r h o t i t e on f r a c t u r e s u r f a c e s i n c h e r t y a r g i l l i t e and t u f f a c e o u s r o c k s ; (2) d i s s e m i n a t e d p y r i t e i n bands i n f i n e l y l a m i n a t e d c h e r t y a r g i l l i t e and c h e r t ; (3) d i s s e m i n a t e d to n e t - t e x t u r e d c h a l c o p y r i t e and p y r r h o t i t e i n o l i v i n e gabbro a t the n o r t h c o n t a c t o f p e r i d o t i t e ; and (4) weakly d i s s e m i n a t e d c h a l c o p y r i t e and p y r r h o t i t e i n p e r i d o t i t e . 201 C h a l c o p y r i t e and minor p y r r h o t i t e o c c u r as d i s s e m i n a t i o n s , i n q u a r t z -c a l c i t e s t r i n g e r s , and on f r a c t u r e p l a n e s i n c h e r t y a r g i l l i t e , t u f f , and minor grey l i m e s t o n e . Very f i n e - g r a i n e d , weakly d i s s e m i n a t e d to ne a r massive (on a very l o c a l s c a l e ) p y r i t e o c c u r s w i t h i n banded c h e r t and c h e r t y a r g i l l i t e . . P y r i t e i s c o n c e n t r a t e d a l o n g bedding p l a n e s and the o v e r a l l appearance i s s t r a t a b o u n d . D i s s e m i n a t e d t o n e t - t e x t u r e d c h a l c o p y r i t e and p y r r h o t i t e o c c u r w i t h i n the 3 m wide exposure o f o l i v i n e gabbro i n c o n t a c t w i t h p e r i d o t i t e i n the t r e n c h . The s u l p h i d e s become n e a r l y massive a t the base o f the o l i v i n e gabbro. Weak d i s s e m i n a t i o n s o f i n t e r s t i t i a l c h a l c o p y r i t e and p y r r h o t i t e o c c u r i n t h e s e r p e n t i n i z e d p e r i d o t i t e , e s p e c i a l l y near i t s f o o t w a l l c o n t a c t w i t h o l i v i n e gabbro. Summary o f Underground G e o l o g i c I n f o r m a t i o n Rock types e n c o u n t e r e d i n diamond d r i l l h o l e s and underground e x c a v a t i o n s i n c l u d e a l t e r e d v o l c a n i c t u f f , a r g i l l i t e , c h e r t , greywacke, c h e r t pebble c o n g l o m e r a t e , and p e r i d o t i t e and o l i v i n e gabbro. Magnetic p r o f i l e r e s u l t s show the u l t r a m a f i c body d i p p i n g s t e e p l y to the s o u t h . D r i l l h o l e d a t a show an i n t e r f i n g e r e d o r b r a i d e d zone ( r a t h e r than a s h a r p zone) a t the u l t r a m a f i t e / c o u n t r y rock c o n t a c t , i n c l u s i o n s o f c o u n t r y rock i n the complex, and a s h e a r zone j u s t i n s i d e t he u l t r a m a f i t e c o n t a c t . T h i s s h e a r zone o c c u r s a l o n g the pronounced f l e x u r e i n s t r i k e o f the u l t r a m a f i c body and appears to d i p s t e e p l y to the n o r t h . The f l e x u r e plunges 70° t o the west. Convergence o f t h e White R i v e r complex and m i n e r a l i z e d zones i s not a p p a r e n t a t depth. S u s p i c i o n o f a f a u l t a l o n g White R i v e r was c o n f i r m e d by d r i l l i n g . Dip on t h e f a u l t p l a ne i s 70° t o 75°E and w i d t h o f the zone i s 46 m. A d d i t i o n a l s t r a n d s o f the f a u l t o c c u r to the west. 202 A 15 m wide s h a t t e r zone, c o n f o r m a b l e w i t h s t r a t i g r a p h y and w i t h i n h a r d , b r i t t l e v o l c a n i c t u f f s and c h e r t y a r g i l l i t e s , o c c u r s n o r t h o f the u l t r a m a f i t e . One prominent f a u l t w i t h i n the s h a t t e r zone s t r i k e s 295° and d i p s 80°N. T h i s f a u l t forms the n o r t h e r n l i m i t s o f the n i c k e l i f e r o u s ore zone a t t h e 2700 f o o t l e v e l . P y r i t e , c h a l c o p y r i t e , and p y r r h o t i t e o c c u r r e n c e s i n r o c k s o f the T r a n s i t i o n Zone are w e l l documented i n d r i l l l o g s and p r o g r e s s r e p o r t s . S u l p h i d e m i n e r a l s o c c u r d o m i n a n t l y i n the t u f f , c h e r t y t u f f , and c h e r t , and t o a l e s s e r e x t e n t i n a r g i l l i t e , greywacke, and pebbly conglomerate. The s u l p h i d e s a r e w i d e s p r e a d as weak, v e r y f i n e d i s s e m i n a t i o n s to s c a t t e r e d near massive p a t c h e s . The v o l c a n i c t u f f and c h e r t y t u f f c o n t a i n s p y r r h o t i t e and o n l y l e s s e r amounts o f c h a l c o p y r i t e and p y r i t e as t h i n seams l e s s than 5 cm wide and i n patchy d i s s e m i n a t i o n s . S u l p h i d e s a l s o o c c u r i n pods a l o n g the abundant f r a c t u r e s i n the s h a t t e r e d c o u n t r y r o c k . F r a c t u r e s are f i l l e d w i t h p y r r h o t i t e and minor c h a l c o p y r i t e , p y r i t e and p e n t l a n d i t e , w i t h o r w i t h o u t m a g n e t i t e . These m i n e r a l s a l s o o c c u r i n small pods a l o n g s h e a r p l a n e s . Only those s u l p h i d e s i n t h e f r a c t u r e s and s h e a r s a r e n i c k e l i f e r o u s . N i c k e l i f e r o u s zone c o n t a c t s seem s h a r p w i t h l i t t l e a p p a r e n t r e l a t i o n s h i p t o o v e r a l l s u l p h i d e c o n t e n t . P y r r h o t i t e i s more abundant i n the s o u t h e r n ,part o f the m i n e r a l i z e d zone, w i t h p y r i t e g r a d u a l l y becoming more abundant i n the n o r t h e r n h a l f . The amount o f n i c k e l i n the m i n e r a l i z e d rock does not v a r y i n r e l a t i o n t o the r a t i o o f p y r r h o t i t e t o p y r i t e . T h i s m i n e r a l i z e d Main Zone i n the c h e r t y a r g i l l i t e and t u f f appears t o be p a r t l y c o n t r o l l e d by the s h a t t e r zone. Diamond d r i l l h o l e d a t a and a d i t and c r o s s - c u t exposures show the s h a t t e r zone s t r i k i n g e a s t - w e s t and d i p p i n g 75°S. I t has a l e n g t h o f 94 m and a w i d t h o f 15 m. N i c k e l v a l u e s a l s o end a b r u p t l y t o the west w i t h no 203 c o r r e s p o n d i n g d e c r e a s e i n t o t a l s u l p h i d e c o n t e n t , but w i t h an a p p a r e n t i n c r e a s e i n c h a l c o p y r i t e . T h i s main ore zone plunges t o the west, converges w i t h , and i s c u t o f f by the White R i v e r F a u l t . S u l p h i d e s a l s o o c c u r i n the North Zone, up t o 21 m wide, and s i t u a t e d 46 m n o r t h o f t h e Main Zone and r o u g h l y p a r a l l e l t o i t . The h o s t rock i s c h e r t y t u f f and i n t e r b e d d e d c h e r t w i t h a g r e a t e r p r o p o r t i o n o f c h e r t t o t u f f than i n the Main Zone. F r a c t u r i n g and s h a t t e r i n g o f t h e rock i s weak w i t h c o n t r o l o f s u l p h i d e m i n e r a l i z a t i o n b e i n g more s t r a t i g r a p h i c . S u l p h i d e m i n e r a l s a re p y r i t e w i t h c h a l c o p y r i t e and minor p y r r h o t i t e . The n i c k e l c o n t e n t i s g e n e r a l l y low w i t h e r r a t i c h i g h s . The Lower North Zone i s s i t u a t e d west o f White R i v e r and was i n t e r -s e c t e d i n d r i l l h o l e s 30 to 61 m below the lower l e v e l . The zone i s i n s h a t t e r e d t u f f a c e o u s m a t e r i a l and i n t e r b e d d e d c h e r t and i s l i m i t e d t o a narrow a r e a between two s t r a n d s o f the White R i v e r f a u l t zone. N i c k e l v a l u e s a r e e s s e n t i a l l y n e g l i g i b l e i n t h i s zone. A summary o f ore r e s e r v e s and grades f o r 1967 and 1968 i s l i s t e d i n T a b l e A2. COPPER IN NIKOLAI GREENSTONE Q u i l l Creek Mines L i m i t e d  L o c a t i o n The Ram C l a i m Group i s l o c a t e d near t he j u n c t i o n o f Ram and Q u i l l Creeks a p p r o x i m a t e l y 5.6 km s o u t h e a s t o f W e l l g r e e n Mine. A t o t e road l e a v e s t h e W e l l g r e e n road a t the j u n c t i o n between Q u i l l and N i c k e l Creeks and f o l l o w s Q u i l l Creek v a l l e y t o the p r o p e r t y . 204 TABLE A2. Ore Reserves and Grades f o r Canalask D e p o s i t 1967 1968 Reserves:''" Main Zone 345,499 303,582 ( p r o b a b l e ) Lower Main Zone 14,380 73,503 ( p o s s i b l e ) TOTAL: 359,879 390,235 Grades: Main Zone 1.34% Ni 1.41% Ni ( p r o b a b l e ) 1.08% Ni ( p o s s i b l e ) Lower Main Zone 1.44% Ni 1.55% Ni ( e s t i m a t e d 0.04 t o 0.10% Cu) O v e r a l l T o t a l 1.35% Ni 1.35% Ni 1 Reported i n t o n n e s . 205 H i s t o r y o f Development N a t i v e copper nuggets were found f o r y e a r s i n a s s o c i a t i o n w i t h g o l d i n Burwash, Tatamagouche, and Arch C r e e k s , and i n White R i v e r a r e a . D u r i n g l a t e 1965 and e a r l y 1966 P. V e r s l u c e and a s s o c i a t e s l o c a t e d and s t a k e d a copper showing i n Ram Creek. P r o s p e c t i n g and t r e n c h i n g were c a r r i e d out d u r i n g the summer o f 1966 and i n October Q u i l l Creek Mines L t d . was formed under agreement between P. V e r s l u c e and Newmont M i n i n g C o r p o r a t i o n o f Canada L i m i t e d . Newmonts' e x p l o r a t i o n program on the c l a i m s was completed d u r i n g the summer o f 1967. Work i n c l u d e d d e t a i l e d mapping o f g e o l o g y , a geochemical stream sediment s u r v e y , an a i r b o r n e magnetic s u r v e y , b u l l d o z e r t r e n c h i n g i n the v i c i n i t y o f the showings, rock s a m p l i n g , and diamond d r i l l i n g . S u r v e y i n g and s a m p l i n g o f a l l copper o c c u r r e n c e s was conduct e d and r e s u l t s i n d i c a t e d t h a t the o c c u r r e n c e s were h i g h g r a d e , but o f ve r y l i m i t e d e x t e n t . The p r o p e r t y was r e t u r n e d to the owners under t he o p t i o n agreement i n 1967. Geology Upper T r i a s s i c N i k o l a i b a s a l t i s the dominant rock type i n the c l a i m group. I t has minor i n t e r b e d d e d s e d i m e n t a r y u n i t s and d i s c o n f o r m a b l y o v e r l i e s Lower Permian s e d i m e n t a r y r o c k s o f Hasen Creek F o r m a t i o n . Hasen Creek Formation c o n s i s t s o f both f o s s i 1 i f e r o u s and massive l i m e s t o n e , a r g i l l i t e , s h a l e , c o n g l o m e r a t e , and c h e r t . A g e n e r a l s t r a t i g r a p h i c s e c t i o n shows massive to w e l l bedded s i l t y l i m e s t o n e , 18 m t h i c k , o v e r l a i n by a r g i l l i t e , minor s h a l e , and i n t e r b e d s o f c h e r t and l i m e s t o n e , i n t u r n o v e r l a i n by p a l e grey c o r a l l i m e s t o n e , and topped by brown c h e r t pebble c o n g l o m e r a t e . The N i k o l a i b a s a l t c o n t a i n s minor, d i s c o n t i n u o u s beds o f a r g i l l i t e , 206 c h e r t , s h a l e , and l i m e s t o n e i n i t s lower s e c t i o n s . V o l c a n i c f l o w s dominate, but minor b a s a l t i c agglomerate o c c u r s near the base. The flows are dark green t o r e d d i s h - p u r p l e , a p h a n i t i c t o v e r y f i n e - g r a i n e d , and o c c a s -i o n a l l y p o r p h y r i t i c . V e s i c l e s w i t h amygdules o f c h l o r i t e , c a l c i t e , and e p i d o t e are abundant. Massive u n i t s o f b a s a l t are up t o 30 m t h i c k . The rock has been c h l o r i t i z e d and s h e a r e d , and c o n t a i n s numerous q u a r t z -c a l c i t e - e p i d o t e f r a c t u r e f i l l i n g s . M inor f o l d s i n t h e s e d i m e n t a r y r o c k s have axes t r e n d i n g w e s t - n o r t h -w e s t e r l y w i t h plunges o f up t o 10°. F a u l t i n g and s h e a r i n g are m o s t l y w e s t - n o r t h w e s t e r l y w i t h s t e e p n o r t h e r l y t o v e r t i c a l d i p s . Cross f a u l t s , a p p a r e n t l y normal f a u l t s , s t r i k e n o r t h to n o r t h w e s t and have v e r t i c a l o r near v e r t i c a l d i p s . M i n e r a l D e p o s i t s Copper d e p o s i t s c o n s i s t o f c h a l c o c i t e , b o r n i t e , and minor n a t i v e copper and c h a l c o p y r i t e . A s s o c i a t e d p y r i t e and p y r r h o t i t e are e x t r e m e l y r a r e . C h a l c o c i t e i s the most abundant s u l p h i d e , u s u a l l y accompanied by r e l a t i v e l y s m a l l amounts o f b o r n i t e . N a t i v e copper and m a l a c h i t e o c c u r i n amygdules and q u a r t z - e p i d o t e v e i n s as f i n e d i s s e m i n a t i o n s . C u p r i t e i s p r e s e n t l o c a l l y . Newmont d e l i n e a t e d f o u r types o f copper o c c u r r e n c e s : (1) d i s p e r s e d c h a l c o c i t e i n amygdules; (2) n a t i v e copper as d i s s e m i n a t e d f l e c k s and f i b r e s i n massive b a s a l t ; (3) n a t i v e c o p p e r , c h a l c o c i t e , and m a l a c h i t e w i t h o c c a s i o n a l minor b o r n i t e , c h a l c o p y r i t e , a z u r i t e , and c u p r i t e a s s o c i a t e d w i t h q u a r t z , c a l c i t e , and e p i d o t e v e i n i n g and a l t e r a t i o n i n s h e a r zones and a m y g d a l o i d a l b a s a l t ; and (4) c h a l c o c i t e i n e i t h e r f i n e -g r a i n e d " s o o t y " form or l e s s commonly as v e i n l e t s , w i t h minor b o r n i t e , c h a l c o p y r i t e , and m a l a c h i t e , a s s o c i a t e d w i t h c h l o r i t e and s e r p e n t i n e 207 i n s h e a r e d or crumbled b a s a l t . O c c u r r e n c e s (1) and (2) are small or w i d e l y d i s p e r s e d and o f no economic s i g n i f i c a n c e . O c c u r r e n c e (3) i s the most common, but o f v e r y l i m i t e d e x t e n t . A l l o c c u r r e n c e s o f s i g n i f i c a n c e i n t h e a r e a are o f type ( 4 ) . At the Ram Showing, exposed i n Ram Creek, c h l o r i t i z e d and s l i g h t l y s e r p e n t i n i z e d amygdaloidal b a s a l t c o n t a i n s p r e d o m i n a n t l y c h a l c o c i t e , w i t h some b o r n i t e and c h a l c o p y r i t e , o c c u r r i n g as v e i n l e t s a l o n g a zone o f s h e a r i n g . Minor d i s s e m i n a t e d b o r n i t e i s a l s o p r e s e n t i n the more massive b a s a l t exposed nearby. The assay p l a n i n d i c a t e s t h a t i n s u b s u r f a c e , m i n e r a l i z a t i o n i s i r r e g u l a r i n w i d t h and grade, but c o n t i n u i t y e x i s t s o v e r 305 t o perhaps 488 m. Diamond d r i l l h o l e s i n t e r s e c t e d two m i n e r a l -i z e d z o n e s , one a v e r a g i n g 0.30 p e r c e n t copper over 5.8 m, the o t h e r a v e r a g i n g 0.89 p e r c e n t copper o v e r 2.4 m. The l a t t e r i n t e r s e c t i o n was c o r r e l a t e d w i t h 3 meters o f 0.92 p e r c e n t copper found i n a t r e n c h , i n d i c a t i n g a 68°N d i p f o r t h e m i n e r a l i z e d zone. A l i c e Lake Mines L i m i t e d L o c a t i o n The 92 c l a i m s are l o c a t e d a l o n g a mountain c r e s t a t the head o f a t r i b u t a r y o f Tatamagouche Creek, a p p r o x i m a t e l y 11 km s o u t h e a s t o f W e l l g r e e n Mi ne. H i s t o r y o f Development The c l a i m s were s t a k e d o v e r an o l d showing and h e l d by A l i c e Lake Mines L i m i t e d . E l e c t r o m a g n e t i c s u r v e y s conducted i n 1969' and 1970 o u t l i n e d anomalies near a major s h e a r zone. Geology and M i n e r a l D e p o s i t s There a r e two copper showings, 0.8 km a p a r t , t h a t o c c u r i n b a s a l t f l o w s o f t h e N i k o l a i Greenstone. The b a s a l t i s dark green t o p u r p l e and 208 c h a r a c t e r i s t i c a l l y a m y g d a l o i d a l . A 35 cm t h i c k b o r n i t e v e i n s i t s i n a s h e a r zone which s t r i k e s 070° and d i p s 40°NW. A nearby t r e n c h exposes s t r o n g l y f r a c t u r e d b a s a l t , a l s o c o n t a i n i n g b o r n i t e . Both o f thes e o c c u r r e n c e s a r e h e a v i l y s t a i n e d w i t h m a l a c h i t e and a z u r i t e , but are r e l a t i v e l y s m a l l and uneconomic. 209 APPENDIX A2 DESCRIPTIONS OF SAMPLES OF VOLCANIC ROCKS ANALYZED CHEMICALLY 210 STATION CREEK FORMATION  86-1 F i n e - g r a i n e d , g r e y i s h - g r e e n , massive c r y s t a l t u f f . The rock i s composed o f p l a g i o c l a s e and a l t e r e d a u g i t e c r y s t a l s and c r y s t a l fragments s e t i n a v e r y f i n e - g r a i n e d m a t r i x o f p l a g i o c l a s e l a t h s , c l i n o p y r o x e n e , and m a g n e t i t e . A l t e r a t i o n has produced u r a l i . t i c h o r n b l e n d e , s a u s s u r i t e , and patches o f c h l o r i t e and e p i d o t e i n the m a t r i x . The sample was c o l l e c t e d from the W e l l g r e e n p r o p e r t y . 102-1 Grey t o p a l e green a g g l o m e r a t e , c o n s i s t i n g o f subrounded t o s u b a n g u l a r fragments o f b a s a l t i c a n d e s i t e . The m a t r i x i s v e r y f i n e -g r a i n e d and composed o f t i n y l a t h s o f p l a g i o c l a s e and a u g i t e . B a s a l t i c a n d e s i t e fragments a r e c h l o r i t i z e d and both c h l o r i t e and e p i d o t e o c c u r i n t h e m a t r i x . T h i s sample was c o l l e c t e d from an o u t c r o p s t r a t i g r a p h i c a l T y below t h e T r a n s i t i o n Zone near t h e s o u t h e a s t end o f Q u i l l Creek complex. 146-1 F i n e - t o n e a r l y medium-grained, g r e y i s h - g r e e n , massive c r y s t a l t u f f . C r y s t a l s and c r y s t a l fragments a r e m o s t l y p l a g i o c l a s e , s e r p e n t i n i z e d o l i v i n e , and u r a l i t i z e d a u g i t e . The m a t r i x i s v e r y f i n e - g r a i n e d and a l t e r e d t o c a l c i t e , c h l o r i t e , and e p i d o t e p a t c h e s . T h i s sample was c o l l e c t e d a l o n g Burwash Creek i m m e d i a t e l y e a s t o f the Tatamagouche Creek - Burwash Creek j u n c t i o n . 219-1 Grey t o g r e e n i s h - g r e y , massive v o l c a n i c b r e c c i a , c o n t a i n i n g s u b a n g u l a r t o a n g u l a r b a s a l t i c a n d e s i t e fragments o f h i g h l y v a r i a b l e s i z e . The m a t r i x i s a f i n e - g r a i n e d c r y s t a l t u f f . C r y s t a l fragments 211 i n c l u d e s a u s s u r i t i z e d p l a g i o c l a s e and minor u r a l i t i z e d and c h l o r i -t i z e d a u g i t e . C a l c i t e patches and s t r i n g e r s appear i n t h e m a t r i x a l o n g w i t h p l a g i o c l a s e , a u g i t e , and minor q u a r t z . The sample was taken from an exposure near t h e No. 2 showing a t the W e l l g r e e n p r o p e r t y . 1139-3 F i n e - g r a i n e d , g r e e n i s h - g r e y , massive t u f f . The rock c o n s i s t s o f minor c r y s t a l fragments o f p l a g i o c l a s e and a u g i t e i n a m a t r i x o f f i n e r g r a i n s o f t h e same m i n e r a l s . Patches o f c h l o r i t e , c a l c i t e , and e p i d o t e a r e d i s t r i b u t e d t h r o u g h o u t the m a t r i x a l o n g w i t h minor patches o f s e r p e n t i n e ( a f t e r o l i v i n e ? ) . T h i s sample was c o l l e c t e d from an o u t c r o p a l o n g the r i d g e e a s t - s o u t h e a s t o f L i n d a Creek and at the s o u t h e a s t end o f Q u i l l Creek p e r i d o t i t e . 1181-3 G r e y i s h - g r e e n , massive a g g l o m e r a t e , composed o f s u b a n g u l a r fragments o f b a s a l t i c a n d e s i t e i n a f i n e - t o n e a r l y medium-grained c r y s t a l t u f f m a t r i x . C r y s t a l fragments i n c l u d e p l a g i o c l a s e , a u g i t e , and minor h o r n b l e n d e . A l t e r a t i o n has produced s a u s s u r i t e , u r a l i t e , c h l o r i t e and c a l c i t e p a t c h e s , and p e r v a s i v e e p i d o t e . The sample was c o l l e c t e d from t h e west bank o f White R i v e r n o r t h o f t h e mouth o f M i l e s Creek. P1006 Medium g r e e n , f i n e - g r a i n e d , f o l i a t e d b a s a l t i c a n d e s i t e f l o w , showing s t r e t c h e d and f l a t t e n e d c h l o r i t e amygdules and p e r v a s i v e c h l o r i t e and e p i d o t e a l t e r a t i o n . Main m i n e r a l s are a u g i t e and p l a g i o -c l a s e w i t h l e s s e r amounts o f h o r n b l e n d e , m a g n e t i t e , and i n t e r s t i t i a l q u a r t z . T h i s sample was taken from t h e P i c k h a n d l e p r o p e r t y . P1016 G r e y i s h - g r e e n , a p h a n i t i c , w e l l f o l i a t e d b a s a l t i c a n d e s i t e f l o w , 212 c o n s i s t i n g o f p l a g i o c l a s e and a u g i t e w i t h minor h o r n b l e n d e and m a g n e t i t e . The rock i s p e r v a s i v e l y c h l o r i t i z e d and e p i d o t i z e d . Some c h l o r i t e patches may be amygdules t h a t have been s t r e t c h e d and o b s c u r e d by d e f o r m a t i o n . T h i s sample was c o l l e c t e d from an exposure on t h e P i c k h a n d l e p r o p e r t y . P1048A Medium g r e e n , a p h a n i t i c t o v e r y f i n e - g r a i n e d , f o l i a t e d b a s a l t i c a n d e s i t e f l o w . M i n e r a l c o n s t i t u e n t s are p l a g i o c l a s e and a u g i t e w i t h a c c e s s o r y h o r n b l e n d e and m a g n e t i t e . C h l o r i t e patches a re s c a t t e r e d t h r o u g h o u t t h e rock and minor e p i d o t e a l t e r a t i o n i s p r e s e n t . The sample was c o l l e c t e d from t h e P i c k h a n d l e p r o p e r t y . P1049 G r e y i s h - g r e e n , v e r y f i n e - g r a i n e d b a s a l t i c a n d e s i t e f l o w , c o n s i s t i n g o f a u g i t e and p l a g i o c l a s e w i t h l e s s e r amounts o f mag n e t i t e and horn^* b l e n d e . A l t e r a t i o n has produced p e r v a s i v e e p i d o t e and patchy c h l o r i t e and c a l c i t e , which may r e p r e s e n t r e l i c t amygdules. The sample was taken from t h e P i c k h a n d l e p r o p e r t y . NIKOLAI GREENSTONE 55-1 Dark g r e e n , v e r y f i n e - g r a i n e d , a m y g d a l o i d a l b a s a l t f l o w . The roc k c o n s i s t s o f g l o m e r o p o r p h y r i t i c p l a g i o c l a s e p h e n o c r y s t s i n a groundmass o f f i n e c r y s t a l s o f p l a g i o c l a s e , a u g i t e , and i n t e r g r a n u l a r m a g n e t i t e . Amygdule c o n s t i t u e n t s i n c l u d e e p i d o t e , c a l c i t e , and c h l o r i t e . E p i d o t i z a t i o n i s p e r v a s i v e . T h i s sample was c o l l e c t e d a l o n g t h e r i d g e n o r t h e a s t o f Arch Canyon complex. 213 114-1 R e d d i s h , a p h a n i t i c b a s a l t i c f l o w , which i n t h i n s e c t i o n appears g l o m e r o p o r p h y ' r i t i c w i t h p l a g i o c l a s e p h e n o c r y s t s s e t i n a groundmass o f p l a g i o c l a s e , a u g i t e , and h e m a t i t e . M a l a c h i t e i s abundant as f r a c t u r e c o a t i n g s i n the exposed r o c k . T h i s sample was c o l l e c t e d from the r i d g e n o r t h o f t h e Q u i l l Creek Mines p r o p e r t y . 150-1 Dark g r e e n , v e r y f i n e - g r a i n e d b a s a l t f l o w w i t h a s e r i a t e porphy-r i t i c t e x t u r e due to p l a g i o c l a s e p h e n o c r y s t s . The groundmass c o n s i s t s o f p l a g i o c l a s e , a u g i t e , m a g n e t i t e , and c h l o r i t e and c a l c i t e p a t c h e s . Amygdules c o n t a i n c a l c i t e , c h l o r i t e , and e p i d o t e . The sample was t a k e n from t h e A l i c e Lake Mines p r o p e r t y . 182-1 Reddish t o p u r p l e , v e r y f i n e - g r a i n e d b a s a l t f l o w . The rock i s g l o m e r o p o r p h y r i t i c w i t h a u g i t e and minor p l a g i o c l a s e p h e n o c r y s t s . Groundmass c o n s t i t u e n t s i n c l u d e a u g i t e , p l a g i o c l a s e , and hematite a l o n g w i t h minor c h l o r i t e and c a l c i t e p a t c h e s . C h l o r i t e a l s o o c c u r s i n amygdules. T h i s sample was c o l l e c t e d from the h i g h e s t peak n o r t h o f W e l l g r e e n Mine. 1045-1 R e d d i s h , f i n e - t o n e a r l y medium-grained b a s a l t f l o w , d i s p l a y i n g a f i n e d i a b a s i c t e x t u r e . P l a g i o c l a s e l a t h s are p a r t l y s e r i c i t i z e d and a u g i t e c o n t a i n s patchy c a l c i t e . M a g n e t i t e and h e m a t i t e are i n t e r g r a n u l a r . S e r p e n t i n e (pseudomorphic a f t e r o l i v i n e ? ) i s p r e s e n t as a minor c o n s t i t u e n t . The sample was c o l l e c t e d a l o n g Burwash Creek. 1045-2 Dark g r e e n i s h , v e r y f i n e - g r a i n e d b a s a l t f l o w . T h i s rock i s 214 g l o m e r o p o r p h y r i t i c w i t h a l t e r e d p l a g i o c l a s e l a t h s i n a f i n e r g r a i n e d groundmass o f p l a g i o c l a s e , a u g i t e , s e r p e n t i n e , and i n t e r s t i t i a l m a g n e t i t e and g l a s s . P l a g i o c l a s e i s p a r t l y a l t e r e d t o s e r i c i t e and c a l c i t e . The sample was taken from an exposure a l o n g Burwash Creek. 1045-5A Re d d i s h , a p h a n i t i c , g l o m e r o p o r p h y r i t i c b a s a l t f l o w . P l a g i o c l a s e p h e n o c r y s t s are p a r t l y s a u s s u r i t i z e d . The groundmass c o n s i s t s o f p l a g i o c l a s e , a u g i t e , s e r p e n t i n e p a t c h e s , and i n t e r s t i t i a l g l a s s . The rock i s h e m a t i t e - r i c h and amygdules c o n t a i n c a l c i t e and c h l o r i t e . T h i s sample was taken from a flow top i n a b a s a l t exposure a l o n g Burwash Creek. 1045-5B Dark g r e e n , v e r y f i n e - g r a i n e d b a s a l t f l o w . The amygdules c o n s i s t o f c h l o r i t e , c a l c i t e , and q u a r t z . The m i n e r a l o g y i s the same as t h a t f o r 1045-5A, e x c e p t t h a t m a g n e t i t e i s p r e s e n t here i n s t e a d o f h e m a t i t e . T h i s sample was taken from the lower p a r t o f a b a s a l t f l o w exposed a l o n g Burwash Creek. 1045-6 Medium g r e e n , v e r y f i n e - g r a i n e d b a s a l t f l o w c o n t a i n i n g s a u s s u r i t i z e d p l a g i o c l a s e , a u g i t e , i n t e r g r a n u l a r m a g n e t i t e , and patches o f c h l o r i t e . The rock has a f i n e , somewhat d i a b a s i c t e x t u r e . Amygdules a r e composed o f e p i d o t e , q u a r t z , and c h l o r i t e . T h i s sample was c o l l e c t e d a l o n g Burwash Creek j u s t downstream from t h e j u n c t i o n w i t h Tatamagouche Creek. 1140-4 Dark g r e e n , f i n e - g r a i n e d , f o l i a t e d and s h e a r e d b a s a l t f l o w , showing a r e l i c t d i a b a s i c t e x t u r e . P l a g i o c l a s e l a t h s are p a r t l y 215 s e r i c i t i z e d w i t h patches o f c a l c i t e and a u g i t e g r a i n s are a l t e r e d t o c h l o r i t e and c a l c i t e . S k e l e t a l m a g n e t i t e i s s c a t t e r e d t h r o u g h o u t the r o c k . T h i s sample was c o l l e c t e d from the r i d g e n o r t h e a s t o f Arch Creek and n o r t h - n o r t h w e s t o f W e l l g r e e n Mine. APPENDIX A3 ANALYTICAL PRECISION FOR WHOLE ROCK AND TRACE ELEMENT ANALYSES 217 INTRODUCTION A t o t a l o f 51 samples and 10 d u p l i c a t e s were a n a l y z e d f o r major, minor, and t r a c e e l e m e n t s . Four groups o f r o c k s were a n a l y z e d - Lower Permian S t a t i o n Creek v o l c a n i c r o c k s , Upper T r i a s s i c N i k o l a i b a s a l t s , Lower T r i a s s i c Kluane g a b b r o - u l t r a m a f i c complexes, and T r i a s s i c Maple Creek gabbros. Rocks were s e l e c t e d on the b a s i s o f t h e i r f r e s h n e s s , c r o s s s e c t i o n a l d i s t r i b u t i o n w i t h i n t h e i r r e s p e c t i v e map u n i t s , and t h e i r d i s t r i b u t i o n t h r o u g h o u t the Q u i l l Creek and White R i v e r a r e a s . A n a l y s e s f o r S i 0 2 , A 1 2 0 3 , MnO, CaO, Na 20, KpO, P 2 0 5 , L.O.I., Co, and C r , u s i n g c l a s s i c a l methods, were s u p p l i e d by MIN-EN L a b o r a t o r i e s i n North Vancouver. T i 0 2 , F e T , MgO, S, Cu, N i , Zn, Ba, S r , Rb, Nb, Z r , and Y were a n a l y z e d by the w r i t e r on the P h i l l i p s XRF S p e c t r o m e t e r a t the Department o f G e o l o g i c a l S c i e n c e s , U n i v e r s i t y o f B r i t i s h Columbia. D e t a i l s o f l a b p r o c e d u r e s a r e a v a i l a b l e i n A P r e l i m i n a r y Report on A n a l y t i c a l Data, 1979, f o r The A r c t i c and A l p i n e I n s t i t u t e o f the U n i v e r s i t y o f B r i t i s h Columbia. ANALYTICAL PRECISION D u p l i c a t e runs were performed on 10 o f the 51 samples a n a l y z e d and were used as a t e s t o f the a n a l y t i c a l p r e c i s i o n ( T a b l e s A l and A2). Data f o r each element were a r r a n g e d i n t o groups o f t h r e e or more (depending on c o n c e n t r a t i o n l e v e l s ) , such t h a t p r e c i s i o n c o u l d be d e t e r m i n e d on each range o f v a l u e s - e s p e c i a l l y f o r more v a r i a b l e elements such as Cu and N i . T h i s p r e v e n t e d u n r e a l i s t i c a l l y good p r e c i s i o n i n lower c o n c e n t r a -t i o n g r o u p s . C a l c u l a t i o n s o f a n a l y t i c a l p r e c i s i o n were a t the 95 p e r -218 TABLE A l . A n a l y t i c a l P r e c i s i o n f o r Major and Minor E l e m e n t s . ELEMENT DATA RANGE MEAN STANDARD DEVIATION VARIANCE PRECISION (±%)1 S i 0 2 37.50 to 49.50 44.00 .41 1.68 2 T i 0 9 .262 to .389 .345 .005 .000025 3 L. .447 to .606 .512 .007 .000049 3 .786 to 1.576 1.191 .014 .000196 2 A1 90., 2.32 to 6.96 4.03 .10 .010 5 C o 12.18 to 15.52 13.93 .16 .025 2 F e T 9.46 to 13.99 11.58 .38 .142 6 MnO .100 t o .195 .144 .007 .000049 9 MgO 6.40 to 14.31 8.71 .34 .115 7 26.22 to 38.65 33.03 .53 .276 3 CaO 0.60 to 3.30 2.47 .06 .0036 5 7.05 t o 10.45 8.90 .27 .073 6 Na o0 0.52 to 0.71 0.61 .02 .0004 7 1.40 t o 4.71 2.94 .07 .0049 5 K 9 0 0.27 to 0.49 0.36 .04 .0016 20 c 1.01 to 1.76 1.32 .05 .0025 8 .156 to .229 .186 .033 .0011 35 c. 0 .247 t o .316 .284 .039 .0015 27 .330 t o .697 .515 .044 .0019 17 L.O.I. 1.45 t o 4.49 3.47 .44 .194 25 5.29 to 9.60 7.24 .24 .058 7 S .000 to .112 .051 .021 .00044 82 .199 to .455 .299 .127 .016 84 TOTAL ( a t 95% c o n f . l e v e l ) 1.88 ( a t 97.5% c o n f . l e v e l ) .95 .90 2.14 ( a t 99% c o n f . l e v e l ) 2.47 1 Formula i s : P +% = 1.98 x s x 100% P = p r e c i s i o n x s = s t a n d a r d d e v i a t i o n x = mean o f d a t a range 1.98 = used f o r 95% c o n f . l e v e l 219 TABLE A2. A n a l y t i c a l P r e c i s i o n f o r T r a c e Elements. ELEMENT DATA RANGE MEAN STANDARD VARIANCE PRECISION DEVIATION (+%)1 Cu 5 to 75 37 10 100 53 110 to 195 142 4 16 6 344 t o 482 428 15 225 7 Ni 26 t o 75 54 4 16 15 102 to 371 193 3 9 3 1108 to 2221 1678 11 121 1 Co 38 t o 50 43 3 9 14 56 t o 74 65 3 9 11 Cr 140 to 380 266 13 169 10 1200 t o 3100 2439 160 25600 13 Zn 60 to 71 66 1 1 3 75 t o 92 81 1 1 4 Ba 1 to 46 19 3 9 33 56 t o 75 67 4 16 11 238 t o 451 371 4 16 2 S r 3.27 t o 60.71 40.55 2.1 4.4 10 144.7 t o 179.2 166.8 2.1 4.4 2 243.8 t o 393.2 314.4 2.4 5.8 1 Rb 0.98 to 5.37 2.72 .26 .068 19 23.34 to 31.21 25.62 .37 .137 3 Nb 3.5 to 11.3 6.0 .81 .656 27 Zr 22 to 40 33 1.4 2 9 50 to 118 79 1.4 2 4 Y 8.6 t o 13.6 10.5 .57 .325 11 17.3 t o 22.5 20.4 1.03 1.06 10 1 Formula i s : •P +% = 1.98 x s x 100% P = p r e c i s i o n X s = s t a n d a r d d e v i a t i o n x = mean o f data range 1.98 = used f o r 95% c o n f . l e v e l 220 c e n t c o n f i d e n c e l e v e l . Reasonable p r e c i s i o n ( l e s s than o r equal to 25 p e r c e n t ) was o b t a i n e d f o r most elements and good p r e c i s i o n ( l e s s than or equal to 10 p e r c e n t ) was o b t a i n e d f o r a l l o f the f o l l o w i n g : S i 0 2 , T i 0 2 , A l 2 ^ 3 ' F eT> M r |0> M90> CaO, ^ 0 , Zn, S r , and Zr r e s u l t s . P r e c i s i o n i s e x t r e m e l y poor ( g r e a t e r than or equal t o 30 p e r c e n t ) f o r P^O^ v a l u e s l e s s than 0.23 weight per-c e n t , S, Cu v a l u e s l e s s than 100 ppm, and Ba v a l u e s l e s s than 50 ppm. A p r e c i s i o n e s t i m a t e o f the i d e a l 100 w e i g h t p e r c e n t t o t a l a n a l y s i s was de t e r m i n e d by summing the l a r g e s t v a r i a n c e f o r each i n d i v i d u a l e lement. T a b l e A l shows the t o t a l p r e c i s i o n a t v a r i o u s l e v e l s o f s i g n i f i c a n c e . 

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