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Geology and genesis of the wolf precious metal epithermal prospect and the capoose base and precious… Andrew, Kathryn Pauline Elizabeth 1988

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G E O L O G Y AND G E N E S I S O F T H E WOLF P R E C I O U S M E T A L E P I T H E R M A L P R O S P E C T AND T H E C A P O O S E B A S E AND P R E C I O U S M E T A L P O R P H Y R Y - S T Y L E P R O S P E C T , C A P O O S E L A K E A R E A , C E N T R A L B R I T I S H C O L U M B I A By KATHRYN P A U L I N E E L I Z A B E T H ANDREW B . S c , The U n i v e r s i t y o f B r i t i s h Columbia, 1985 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF M A S T E R O F S C I E N C E i n THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF GEOLOGICAL SCIENCES We accept t h i s t h e s i s as conforming 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 1988 © Kathryn P a u l i n e E l i z a b e t h Andrew, 1988 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of G e o l o g i c a l S c i e n c e s The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date A p r i l 2 0 t h , 1988 . DE-6(3/81) A B S T R A C T The Wolf and Capoose pr o s p e c t s r e p r e s e n t two d i s t i n c t l y d i f f e r e n t types of p r e c i o u s metal d e p o s i t s i n v o l c a n i c rocks of the S t i k i n i a t e r r a n e , c e n t r a l B r i t i s h Columbia. At the Wolf prospect, a u r i f e r o u s and a r g e n i f e r o u s m e t a l l i c m i n e r a l s are i n bladed quartz-carbonate v e i n s and h e t e r o l i t h i c b r e c c i a s w i t h i n L u t e t i a n c a l c - a l k a l i n e r h y o l i t e of the Ootsa Lake Group. Electrum, n a t i v e s i l v e r , and s i l v e r s u l p h o s a l t s occur as i n c l u s i o n s i n and a d j a c e n t t o p y r i t e i n f i v e s i l i c i c zones which have e i g h t r e c o g n i s a b l e phases of v e i n i n g and b r e c c i a t i o n and are bordered by a r g i l l i c and s e r i c i t i c a l t e r e d r h y o l i t e . F l u i d i n c l u s i o n s d e f i n e growth zones i n p r e c i o u s metal-bearing q u a r t z -carbonate v e i n s and p r e c i o u s metal-poor drusy quartz v e i n s . The i n c l u s i o n s are primary, two-phase, l i q u i d - r i c h , low s a l i n i t y , and low C0 2. Homogenization temperatures of quartz-carbonate v e i n s are 270°C and 170°C and i n the l a t e drusy quartz v e i n s , 250°C. Oxygen and hydrogen i s o t o p e compositions of v e i n quartz, r h y o l i t e , and a l k a l i f e l d s p a r phenocrysts i n d i c a t e t h a t d e p o s i t i o n a l f l u i d s were 0 d e p l e t e d by 4 t o 9 ° / 0 0 . Ootsa Lake Group rocks a t Wolf are formed by e x p l o s i v e e r u p t i o n s and flows, r e l a t e d t o a r i n g f a u l t . F l a t - l y i n g r h y o l i t e t u f f s and flows are i n t r u d e d by c o g e n e t i c s t o c k s and dykes i n a c a l d e r a c o l l a p s e s e t t i n g . P r e c i o u s metal d e p o s i t i o n o c c u r r e d as one event r e l a t e d t o quartz-carbonate v e i n s . L a t e r drusy quartz v e i n s p r e c i p i t a t e d from a i i i d i f f e r e n t f l u i d . Primary f l u i d i n c l u s i o n homogenization temperatures show t h a t f l u i d s which d e p o s i t e d q u a r t z -carbonate were b o i l i n g and e x i s t e d under both h y d r o s t a t i c and near l i t h o s t a t i c p r e s s u r e s a t depths of about 100 m. Oxygen and hydrogen i s o t o p e compositions i n d i c a t e a h i g h degree of i s o t o p i c exchange between r h y o l i t e and l a r g e volumes of low - L O0 content meteoric f l u i d s . The f l u i d s e volved t o a n o n - b o i l i n g , lower s a l i n i t y , extremely 1 8 0 d e p l e t e d , p r e c i o u s metal-poor v a r i e t y which p r e c i p i t a t e d l a t e drusy quartz v e i n s . G e o l o g i c a l s e t t i n g , v e i n and b r e c c i a t e x t u r e s , a l t e r a t i o n , metal d i s t r i b u t i o n and d e p o s i t i o n a l f l u i d e v o l u t i o n a t Wolf resemble a low sulphur, e p i t h e r m a l hot s p r i n g or s i l i c i f i e d stockwork d e p o s i t . At the Capoose prospect, a u r i f e r o u s and a r g e n i f e r o u s m e t a l l i c m i n e r a l s occur as i n c l u s i o n s w i t h i n d i s s e m i n a t e d galena and s p h a l e r i t e i n c a l c - a l k a l i n e M a a s t r i c h t i a n r h y o l i t e s i l l s i n t r u s i v e i n t o Lower and Middle J u r a s s i c H a zelton Group v o l c a n i c and sedimentary r o c k s . Flow-banded, s p h e r u l i t i c r h y o l i t e s i l l s are preserved w i t h i n a minor h o r s t . S p e s s a r t i n e s i n the s i l l s are s i m i l a r i n composition t o p l u t o n i c garnets w i t h l e s s than 5% change i n end member composition from rim t o core. They occur a d j a c e n t t o disseminated, aggregate and v e i n galena, s p h a l e r i t e , p y r i t e , a r s e n o p y r i t e and c h a l c o p y r i t e . Sulphide and s p e s s a r t i n e accummulations are commonly surrounded by muscovite and quartz coronas. Sulphide poor quartz and c a l c i t e v e i n i n g i s i n h o r n f e l s e d Hazelton Group rocks p e r i p h e r a l t o the s i l l s . P h y l l i c a l t e r a t i o n i s r e s t r i c t e d t o the s i l l s and o v e r p r i n t s m i n e r a l i z e d zones. Primary two-phase, l i q u i d - r i c h , low s a l i n i t y , low C0 2 f l u i d i n c l u s i o n s from l a t e s i l i c a t e v e i n s homogenize from 285°C t o 335°C. R h y o l i t e s i l l s are not d e p l e t e d i n x o 0 whereas s e r i c i t e , quartz and c a l c i t e a re. S p e s s a r t i n e i n r h y o l i t e s i l l s a t Capoose c r y s t a l l i z e d as l a t e phenocrysts s t a b i l i z e d by h i g h manganese content. They p r o v i d e d a nucleus f o r s u l p h i d e d e p o s i t i o n s h o r t l y a f t e r s i l l emplacement i n groundwater s a t u r a t e d , permeable H a z e l t o n Group rocks. C o o l i n g , c r y s t a l l i z a t i o n and f r a c t u r e development i n the s i l l s i n i t i a t e d hydrothermal c i r c u l a t i o n and p h y l l i c a l t e r a t i o n with l a t e quartz and c a l c i t e v e i n s r e l a t e d t o c o l l a p s e of the hydrothermal system. Lead-zinc m i n e r a l i z a t i o n o c c u r r e d as two events, w i t h o n l y one r e l a t e d t o p r e c i o u s metal and copper d e p o s i t i o n . Oxygen i s o t o p e compositions of quartz-garnet m i n e r a l separate p a i r s i n d i c a t e c r y s t a l l i z a t i o n of garnets and s u l p h i d e s from magmatic f l u i d s a t temperatures from 528°C t o 725°C. S e r i c i t e , quartz and c a l c i t e p r e c i p i t a t e d from m e t e o r i c f l u i d s . In summary, hydrothermal f l u i d s a t the Capoose p r o s p e c t evolved from e a r l y , h i g h temperature magmatic f l u i d s t o l a t e lower temperature, low s a l i n i t y , m eteoric f l u i d s . The g e o l o g i c a l s e t t i n g , s i l i c a t e and s u l p h i d e mineralogy, a l t e r a t i o n , metal d i s t r i b u t i o n and d e p o s i t i o n a l f l u i d compositions a t Capoose resemble a low-grade, e p i g e n e t i c , i n t r u s i o n - r e l a t e d , p o r p h y r y - s t y l e d e p o s i t . V F r o n t i s p i e c e above - View o f t h e Wolf P r o s p e c t l o o k i n g west showing t h e c h a r a c t e r i s t i c low r e l i e f and t r e e c o v e r e d a r e a . F r o n t i s p i e c e below - View l o o k i n g n o r t h e a s t t o Zone 1 a t t h e Capoose P r o s p e c t on Fawnie Range. R e c e s s i v e l i t h i c wacke u n i t s a r e g r a s s - c o v e r e d , r h y o l i t e s i l l s a r e b a r e . S t r a t i g r a p h y d i p s o b l i q u e l y t o t h e l e f t and toward t h e f o r e ground a t a p p r o x i m a t e l y 40°. TABLE OF CONTENTS page TITLE PAGE . . . i ABSTRACT i i FRONTISPIECES V TABLE OF CONTENTS. v i LIST OF TABLES i x LIST OF FIGURES x i i i LIST OF PLATES x x i ACKNOWLEDGEMENTS x x i v CHAPTER 1 - INTRODUCTION: THE CAPOOSE LAKE AREA 1 1.1 L o c a t i o n and Access 1 1. 2 Physiography 1 1.3 Pr e v i o u s Work and E x p l o r a t i o n H i s t o r y 3 1.4 O b j e c t i v e s 4 CHAPTER 2 - REGIONAL GEOLOGY 6 2.1 T e c t o n i c S e t t i n g 6 2.2 Geology o f the Capoose Lake Area 8 CHAPTER 3 - THE WOLF PRECIOUS METAL EPITHERMAL PROSPECT: GEOLOGY AND GENESIS 11 3.1 L o c a t i o n and Access 11 3.2 Geology 11 3.2.1 I n t r o d u c t i o n 11 3.2.2 S t r a t i g r a p h y and Pe t r o l o g y 11 3.2.3 S t r u c t u r e . . . . . 24 3.2.4 Metamorphism.... 26 3.3 Petroc h e m i s t r y 2 6 3.3.1 Sample P r e p a r a t i o n and A n a l y s i s 26 3.3.2 E r r o r A n a l y s i s . ....29 3.3.3 E l i m i n a t i o n o f Most A l t e r e d Data 31 3.3.4 Chemical Rock C l a s s i f i c a t i o n 36 3.3.5 P e t r o g e n e s i s . 4 6 3.4 Dating 51 3.4.1 K-Ar • .51 3.4.2 Palynology 53 3.5 M i n e r a l i z a t i o n and A l t e r a t i o n . . . 56 3.5.1 D e s c r i p t i o n of Zones 56 3.5.2 Character o f Veins and B r e c c i a s ..75 3.5.3 Ore Pe t r o l o g y 79 3.5.4 Metal D i s t r i b u t i o n ..86 3.5.5 D i s c u s s i o n 86 3.6 Hydrothermal Environment o f D e p o s i t i o n 101 3.6.1 F l u i d I n c l u s i o n Study... 102 3.6.1.1 Sample P r e p a r a t i o n and A n a l y s i s . . . . 102 3.6.1.2 E r r o r A n a l y s i s 108 3.6.1.3 F l u i d I n c l u s i o n Petrography 108 3.6.1.4 F r e e z i n g and Heating Data.... 115 3.6.1.5 I n t e r p r e t a t i o n 121 3.6.2 S t a b l e Isotope Study 132 3.6.2.1 Sample P r e p a r a t i o n and A n a l y s i s . . . . 133 v i i page 3.6.2.2 E r r o r A n a l y s i s ...139 3.6.2.3 I s o t o p i c Composition of Hydrothermal F l u i d s 139 3.6.2.4 Water t o Rock R a t i o . . . . . . . . 143 3.6.2.5 Geothermometry ..147 3.6.2.6 I n t e r p r e t a t i o n 148 3.7 Con c l u s i o n s 153 3.7.1 O r i g i n 153 3.7.2 Deposit Model ...156 C H A P T E R 4 - T H E CAPOOSE B A S E AMD P R E C I O U S M E T A L PORPHYRY-S T Y L E P R O S P E C T : GEOLOGY AMD G E N E S I S ...162 4.1 L o c a t i o n and Access 162 4.2 Geology 162 4.2.1 I n t r o d u c t i o n 162 4.2.2 S t r a t i g r a p h y and P e t r o l o g y 163 4.2.3 S t r u c t u r e 171 4.2.4 Metamorphism 171 4. 3 Pet r o c h e m i s t r y 174 4.3.1 Sample P r e p a r a t i o n and A n a l y s i s 174 4.3.2 E r r o r A n a l y s i s 17 6 4.3.3 E l i m i n a t i o n o f Most A l t e r e d Data 178 4.3.4 Chemical Rock C l a s s i f i c a t i o n 179 4.4 Dating 189 4.4.1 Recent F o s s i l I d e n t i f i c a t i o n ....189 4.4.2 K-Ar 189 4.4.3 Galena Lead Isotopes 192 4.4.4 Summary 192 4.5 O r i g i n o f Garnet i n R h y o l i t e S i l l s 192 4.5.1 I n t r o d u c t i o n 192 4.5.2 F i e l d R e l a t i o n s 195 4.5.3 P e t r o g r a p h i c C h a r a c t e r i s t i c s 195 4.5.4 Microprobe Compositions 200 4.5.4.1 A n a l y t i c a l Techniques 200 4.5.4.2 Microprobe Data 201 4.5.5 Oxygen Isotope Compositions 205 4.5.6 D i s c u s s i o n , 213 4.6 M i n e r a l i z a t i o n and A l t e r a t i o n . . . 221 4.6.1 D e s c r i p t i o n of Zones 223 4.6.2 Ore P e t r o l o g y 224 4.6.3 S i l i c a t e P e t r o l o g y 235 4.6.4 Metal D i s t r i b u t i o n 236 4.6.5 D i s c u s s i o n 240 4.7 Hydrothermal Environment of D e p o s i t i o n 246 4.7.1 F l u i d I n c l u s i o n Study 247 4.7.1.1 Sample P r e p a r a t i o n and A n a l y s i s . . . . 247 4.7.1.2 E r r o r A n a l y s i s 249 4.7.1.3 F l u i d I n c l u s i o n Petrography 249 4.7.1.4 F r e e z i n g and Heating Data 252 4.7.1.5 I n t e r p r e t a t i o n 255 4.7.2 S t a b l e Isotope Study ...259 4.7.2.1 Sample P r e p a r a t i o n and An a l y s i s . . . . 2 5 9 4.7.2.2 E r r o r A n a l y s i s 264 v i i i page 4.7.2.3 Geothermometry 264 4.7.2.4 I s o t o p i c Composition of M i n e r a l i z i n g F l u i d s . . . . 266 4.7.2.5 I s o t o p i c Composition o f Po s t -M i n e r a l i z i n g F l u i d s 267 4.7.2.6 Water t o Rock R a t i o o f p o s t -m i n e r a l i z i n g f l u i d s 272 4.7.2.7 I n t e r p r e t a t i o n . . 275 4.8 Co n c l u s i o n s 279 4.8.1 O r i g i n 279 4.8.2 Deposit Model 282 CHAPTER 5 - CONSEQUENCES OF DEPOSIT MODELLING IN THE CAPOOSE LAKE AREA .287 REFERENCES 290 ** APPENDIX 1 ROCK SAMPLES USED IN THIS STUDY 301 APPENDIX 2 WHOLE ROCK ANALYSES: MAJOR ELEMENT OXIDES AND TRACE ELEMENTS 3 06 ( i ) Wolf Prospect 306 ( i i ) Capoose Prospect 311 APPENDIX 3 MICROPROBE ANALYSES OF GARNETS FROM THE CAPOOSE PROSPECT 313 i x LIST OF TABLES page 2.1 C o r r e l a t i o n among major g e o l o g i c a l groups and formations from the Capoose Lake area (NTS:093F), W h i t e s a i l Lake area (NTS:093E), Smithers area (NTS:093L), Gang ranch-Big bar area (NTS:0920) 9 3.1 Grouping of Ootsa Lake Group map u n i t s based on s p a t i a l r e l a t i o n s h i p , complementary l i t h o l o g y , s i m i l a r i t y of d e p o s i t i o n a l environment, and a s s o c i a t e d t e x t u r e s , Wolf prospect, c e n t r a l B r i t i s h Columbia 15 3.2 D u p l i c a t e data and U n i v e r s i t y of B r i t i s h Columbia standard samples used t o determine p r e c i s i o n and accuracy of geochemical analyses a t the Wolf pro s p e c t , c e n t r a l B r i t i s h Columbia ....30 3.3 L e a s t a l t e r e d rock samples used f o r rock c l a s s i f i c a t i o n , chemical c l a s s i f i c a t i o n , p e t r o g e n e s i s and t e c t o n i c d i s c r i m i n a t i o n , Wolf pr o s p e c t , c e n t r a l B r i t i s h Columbia...... 33 3.4 K-Ar ages f o r Ootsa Lake Group v o l c a n i c r o c k s from the Wolf prospect, c e n t r a l B r i t i s h Columbia. Samples are l o c a t e d on F i g u r e 3.5 52 3.5 Palynomorphs i n Fraser-Bend e q u i v a l e n t mid-Miocene e p i c l a s t i c rocks, Wolf prospect, c e n t r a l B r i t i s h Columbia (G.E. Rouse, p e r s . comm. 1988) 55 3.6 Estimated p a r a g e n e t i c sequence of hydrothermal events a t the Wolf prospect, c e n t r a l B r i t i s h Columbia (modified a f t e r Cann, 1984).. 78 3.7 A l t e r a t i o n m i n e r a l s i n rocks of the Ridge and Pond zones determined by X-ray d i f f r a c t i o n a n a l y s i s of r e p r e s e n t a t i v e specimens a t the Wolf p r o s p e c t , c e n t r a l B r i t i s h Columbia. Numbers i n the t a b l e i n d i c a t e the r e l a t i v e abundance of the m i n e r a l ; 1 = most abundant, 4 = l e a s t abundant. Sample l o c a t i o n s are i n F i g u r e 3.5 85 3.8 a) Trace element chemistry of As, Ba, S, and Sb from rocks of the Wolf p r o s p e c t sample s u i t e . Analyses are i n p a r t s per m i l l i o n , b) Trace element chemistry of Ag and Au from rocks of the Wolf p r o s p e c t (from Holmgren and Cann, 1985). S i l v e r a n a l y ses are i n p a r t s per m i l l i o n ; g o l d analyses i n p a r t s per b i l l i o n 87 X page 3.9 Means and standard d e v i a t i o n s determined g r a p h i c a l l y f o r p a r t i t i o n e d metal v a l u e s a t the Wolf p r o s p e c t , c e n t r a l B r i t i s h Columbia 99 3.10 D e s c r i p t i o n s of v e i n samples used f o r f l u i d i n c l u s i o n a n a l y s e s a t the Wolf prospect, c e n t r a l B r i t i s h Columbia. Sample l o c a t i o n s are i n F i g u r e s 3.3 0 and 3.31 106 3.11 P e t r o g r a p h i c , homogenization and f r e e z i n g data f o r . f l u i d i n c l u s i o n s from quartz v e i n s a t Wolf, c e n t r a l B r i t i s h Columbia. Sample l o c a t i o n s are i n F i g u r e s 3.30 and 3.31. Data are presented i n F i g u r e s 3.32 t o 3.38 109 3.12 Summary of e u t e c t i c and l a s t m e l t i n g temperatures from f l u i d i n c l u s i o n s , Wolf prospect, c e n t r a l B r i t i s h Columbia. Sample l o c a t i o n s are i n F i g u r e s 3.30 and 3.31. Data are presented i n F i g u r e s 3.32 and 3.33 119 3.13 Summary of homogenization temperatures from f l u i d i n c l u s i o n s from d i f f e r e n t v e i n types, Wolf p r o s p e c t , c e n t r a l B r i t i s h Columbia. Sample l o c a t i o n s a re i n F i g u r e s 3.30 and 3.31. Data are presented i n F i g u r e s 3.34 t o 3.38 120 3.14 Oxygen i s o t o p e c o m p o s i t i o n s 1 from samples of whole rock, quartz v e i n and phenocrysts, Wolf p r o s p e c t , c e n t r a l B r i t i s h Columbia. Sample l o c a t i o n s are i n F i g . 3.40. Data are p l o t t e d i n F i g u r e s 3.42 and 3.43 135 3.15 D u p l i c a t e data and U n i v e r s i t y o f Saskatchewan 1 standard samples used t o determine p r e c i s i o n and accuracy o f oxygen i s o t o p e analyses a t the Wolf pr o s p e c t , c e n t r a l B r i t i s h Columbia 14 0 3.16 C a l c u l a t e d oxygen i s o t o p e compositions ( s e c t i o n . 3.6.2) and measured hydrogen i s o t o p e c o m p o s i t i o n s 1 o f hydrothermal f l u i d s a t the Wolf p r o s p e c t , c e n t r a l B r i t i s h Columbia 141 3.17 C a l c u l a t e d water t o rock r a t i o s ( s e c t i o n 3.6.2) assuming c l o s e d and open systems a t the Wolf pr o s p e c t , c e n t r a l B r i t i s h Columbia 146 4.1 Grouping of map u n i t s based on s p a t i a l r e l a t i o n s h i p , complementary l i t h o l o g y , s i m i l a r i t y o f d e p o s i t i o n a l environment, and a s s o c i a t e d t e x t u r e s , Capoose pro s p e c t , c e n t r a l B r i t i s h Columbia. 166 x i page 4.2 D u p l i c a t e data and U n i v e r s i t y of B r i t i s h Columbia standard samples used t o determine p r e c i s i o n and accuracy o f geochemical analyses a t the Capoose pr o s p e c t , c e n t r a l B r i t i s h Columbia 177 4.3 Lea s t a l t e r e d rock samples used f o r rock c l a s s i f i c a t i o n , chemical c l a s s i f i c a t i o n , p e t r o g e n e s i s and t e c t o n i c d i s c r i m i n a t i o n , Capoose prospect, c e n t r a l B r i t i s h Columbia 181 4.4 K-Ar ages f o r Capoose r h y o l i t e s i l l s , dykes and the Capoose b a t h o l i t h , Capoose prospect, c e n t r a l B r i t i s h Columbia. Samples are l o c a t e d on F i g u r e 4.4 191 4.5 Compositions, host rocks and environments o f formation f o r garnets o f igneous, r e g i o n a l metamorphic, metasomatic and x e n o c r y s t i c o r i g i n s . . . . 194 4.6 Cameca SX-50 wavelength d i s p e r s i v e e l e c t r o n microprobe analyses of twenty-two p i n k and brown garnets from the Capoose p r o s p e c t . E i g h t elements were determined: S i , T i , A l , Fe, Mg, Ca, Mn, and Na. The average o f 10 probe spots f o r each garnet i s gi v e n . Complete analyses are i n Appendix 3. Sample l o c a t i o n s are i n F i g u r e 4.4... 202 4.7 Average garnet compositions c a l c u l a t e d from e l e c t r o n microprobe analyses of 22 pin k and brown garnets from the Capoose prospect, c e n t r a l B r i t i s h Columbia. Percent change i n endmember composition from rim t o core f o r each garnet i s g i v e n . Sympathetic v a r i a t i o n i n F e 2 + , Mg 2 +, C a 2 + , and Mn 2 + i s a l s o i n d i c a t e d f o r each garnet t r a v e r s e . Sample l o c a t i o n s are i n F i g u r e 4.4 203 4.8 D i s t i n c t i o n i n composition between brown and pin k garnets d e f i n e d by the F - t e s t , Capoose p r o s p e c t , c e n t r a l B r i t i s h Columbia .204 4.9 C a l c u l a t i o n o f a minimum igneous temperature o f formation from garnet and quartz c r y s t a l s i n r h y o l i t e s , Capoose pro p e r t y , c e n t r a l B r i t i s h Columbia ( s e c t i o n 4.5). Sample l o c a t i o n s are i n F i g u r e 4.4 214 4.10 Trace element analyses o f rocks from the Capoose pro s p e c t , c e n t r a l B r i t i s h Columbia. Samples are l o c a t e d i n F i g u r e 4.18 ..238 x i i page 4.11 Means and standard d e v i a t i o n s determined g r a p h i c a l l y f o r p a r t i t i o n e d metal v a l u e s a t the Capoose p r o s p e c t , c e n t r a l B r i t i s h Columbia. Data, p l o t t e d i n F i g u r e 4.19, are from Table 4.10. (Values below the d e t e c t i o n l i m i t were e v a l u a t e d a t an order of magnitude l e s s than the d e t e c t i o n l i m i t . ) . . . . 243 4.12 Homogenization and f r e e z i n g data f o r f l u i d i n c l u s i o n s from quartz and c a l c i t e v e i n s a t Capoose, c e n t r a l B r i t i s h Columbia. Data are p l o t t e d i n F i g u r e s 4.22 and 4.23. Sample l o c a t i o n s are i n F i g u r e 4.21 250 4.13 Summary of e u t e c t i c and l a s t m e l t i n g temperatures from f l u i d i n c l u s i o n s , Capoose p r o s p e c t , c e n t r a l B r i t i s h Columbia. Data are p l o t t e d i n F i g u r e 4.22..253 4.14 Summary of homogenization temperatures from f l u i d i n c l u s i o n s from d i f f e r e n t v e i n types, Capoose pro s p e c t , c e n t r a l B r i t i s h Columbia. Data are p l o t t e d i n F i g u r e 4.23 256 4.15 Oxygen i s o t o p e c o m p o s i t i o n s 1 from samples o f v e i n , whole rock, and phenocrysts, Capoose p r o s p e c t , c e n t r a l B r i t i s h Columbia. Sample l o c a t i o n s a re i n F i g u r e 4.24. Data are p l o t t e d i n F i g u r e 4.25 261 4.16 D u p l i c a t e data and U n i v e r s i t y o f Saskatchewan standard samples used t o determine p r e c i s i o n and accuracy o f oxygen i s o t o p e a n a l y ses a t the Capoose pro s p e c t , c e n t r a l B r i t i s h Columbia 265 4.17 A d i r e c t l y measured hydrogen i s o t o p e composition- 1 and i n d i r e c t l y c a l c u l a t e d oxygen i s o t o p e compositions ( s e c t i o n 4.7.2) of hydrothermal f l u i d s a t the Capoose prop e r t y , c e n t r a l B r i t i s h Columbia...269 4.18 C a l c u l a t e d water t o rock r a t i o s ( s e c t i o n 4.7.2) assuming an open system a t the Capoose pro s p e c t , c e n t r a l B r i t i s h Columbia 273 x i i i LIST OF FIGURES page 1.1 L o c a t i o n of the Wolf and Capoose p r o s p e c t s , Capoose Lake area, c e n t r a l B r i t i s h Columbia... 2 2.1 D i s t r i b u t i o n of major g e o l o g i c a l groups, Capoose Lake area ( a f t e r T i p p e r , 1963; T i p p e r e t a l . , 1979). I n s e t map: L o c a t i o n of the Capoose Lake area w i t h r e s p e c t t o C o r d i l l e r a n T e c t o n i c B e l t s (from Monger e t a l . . 1982) 7 c.-c t 3.1 Geology of the Wolf prospect, Capoose Lake area, c e n t r a l B r i t i s h Columbia. S e c t i o n s A-A', B-B', C-C and D-D7 are i n F i g u r e s 3.2, 3.3, 3.20 and 3.21, r e s p e c t i v e l y 13 3.2 Diamond d r i l l h o l e p l a n of the Wolf p r o s p e c t , c e n t r a l B r i t i s h Columbia. Map i s keyed t o F i g u r e 3.1A 21 3.3 Cross s e c t i o n A-A' a c r o s s the c e n t r a l r i d g e on the Wolf p r o s p e c t ( F i g . 3.1A) showing mid-Eocene Ootsa Lake Group rocks t h r u s t over mid-Miocene e p i c l a s t i c r ocks 22 3.4 Cross s e c t i o n B-B' a c r o s s the southwestern p o r t i o n of the Wolf p r o s p e c t ( F i g . 3.1A) showing s t r a t i g r a p h i c r e l a t i o n s h i p s 25 3.5 Sample l o c a t i o n s f o r whole rock and t r a c e element chemical analyses and X-ray d i f f r a c t i o n a n a l y s e s , Wolf prospect, c e n t r a l B r i t i s h Columbia. A) west h a l f , and B) e a s t h a l f 27 3.6 L o g a r i t h m i c oxide molecular p r o p o r t i o n r a t i o p l o t s (K 20 denominator) f o r comparison of Wolf v o l c a n i c r o c k s t o 'modern' v o l c a n i c s u i t e s and r e t r i e v a l of l e a s t a l t e r e d data (Beswick, 1978). Most dots which r e p r e s e n t rocks from the Wolf p r o s p e c t (Appendix 1A) f a l l predominantly w i t h i n the l i m i t s f o r 'modern' v o l c a n i c s u i t e s . Least a l t e r e d rocks are i n Table 3.3 32 3.7 P l o t of a l k a l i e s v s . s i l i c a f o r a n alyses from the Wolf p r o s p e c t (Table 3.3, boundaries are from MacDonald, 1968, and I r v i n e and Baragar, 1971). Assemblages are s u b - a l k a l i n e ( s e c t i o n 3.2.2), and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = p y r o c l a s t i c rocks, t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s . . . . 37 x i v page 3.8 AFM diagram with analyses from the Wolf p r o s p e c t (Table 3.3, boundaries are from Wager and Deer, 1939). Assemblages are c a l c - a l k a l i n e ( s e c t i o n 3.2.2), and are p l o t t e d u s i n g squares = mafic v o l c a n i c s , diamonds = p y r o c l a s t i c rocks, t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s 38 3.9 Jensen C a t i o n p l o t f o r analyses from the Wolf p r o s p e c t (Table 3.3, boundaries are from Jensen, 1976). Assemblages are c a l c - a l k a l i n e t o t h o l e i i t i c ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g : squares = m a f i c v o l c a n i c s , diamonds = p y r o c l a s t i c rocks, t r i a n g l e s = r h y o l i t e flows, c i r c l e s = i n t r u s i o n s 39 3.10 P l o t o f a l k a l i e s v s . s i l i c a f o r analyses from the Wolf p r o s p e c t (Table 3.3, boundaries are from Le Bas e t a l . , 1986). Assemblages are predominantly r h y o l i t e s ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = p y r o c l a s t i c r o c k s , t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s .40 3.11 T r i a x i a l oxide p l o t ( F e 2 0 3 + FeO + 1/2 (MgO + CaO) vs. A l 2 0 3 / S i 0 2 ) f o r analyses from the Wolf p r o s p e c t (Table 3.3) boundaries from Church, 1975). Assemblages are predominantly r h y o l i t e s ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g : squares = m a f i c v o l c a n i c s , diamonds = p y r o c l a s t i c r o cks, t r i a n g l e s = r h y o l i t e flows, c i r c l e s = i n t r u s i o n s 41 3.12 S i 0 2 vs. Nb/Y p l o t f o r analyses from the Wolf p r o s p e c t (Table 3.3, boundaries from Winchester and Fl o y d , 1977). Assemblages are dominantly r h y o l i t e and r h y o d a c i t e ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = p y r o c l a s t i c r o c ks, t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s . 42 3.13 Z r / T i 0 2 v s . Nb/Y p l o t f o r analyses from the Wolf p r o s p e c t (Table 3.3, boundaries from Winchester and Fl o y d , 1977). Assemblages are dominantly r h y o l i t e and r h y o d a c i t e ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = p y r o c l a s t i c r o c k s , t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s 43 X V page 3.14 K 20 v s . S i 0 2 p l o t f o r analyses from the Wolf p r o s p e c t (Table 3.3, boundaries are from de Rosen-Spence, 1976). A b b r e v i a t i o n s are: LK = low potassium, MK = medium potassium, HK = hig h potassium, VHK = v e r y h i g h potassium, EHK = extremely h i g h potassium. F e l s i c v o l c a n i c assemblages have h i g h (HK) t o ve r y h i g h (VHK) potassium ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g : diamonds = p y r o c l a s t i c rocks, t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s , 45 3.15 Zr/Nb v s . Y/Nb p l o t f o r analyses from the Wolf p r o s p e c t (Table 3.3) shows t h a t the Eocene v o l c a n i c s u i t e i s c o g e n e t i c because the v a r i a n c e i n conserved element r a t i o s f o r the data i s l e s s than the v a r i a n c e a t t r i b u t a b l e t o a n a l y t i c a l u n c e r t a i n t y ..48 3.16 Y/Nb v s . Ti/Nb p l o t f o r analyses from the Wolf p r o s p e c t (Table 3.3) shows t h a t the Eocene v o l c a n i c s u i t e i s c o g e n e t i c because the v a r i a n c e i n conserved element r a t i o s f o r the data i s l e s s than the v a r i a n c e a t t r i b u t a b l e t o a n a l y t i c a l u n c e r t a i n t y 49 3.17 2Ca+Na+K/Ti vs. A l / T i p l o t o f data from the Wolf p r o p e r t y (Table 3.3) t o t e s t the h y p o t h e s i s o f f e l d s p a r f r a c t i o n a t i o n 51 3.18 M i n e r a l i z e d zones of the Wolf pr o s p e c t , Capoose Lake area, c e n t r a l B r i t i s h Columbia. A)west h a l f , and B) e a s t h a l f 57 3.19 Trench map o f the Ridge Zone (F i g u r e 3.18) showing d i s t r i b u t i o n o f v e i n and b r e c c i a types from the Wolf pr o s p e c t , c e n t r a l B r i t i s h Columbia. Gold and s i l v e r grades are i n F i g u r e 3.24 60 3.20 North-south v e r t i c a l s e c t i o n (C-C':Fig. 3.1A) of the Wolf p r o s p e c t from s u r f a c e mapping and core l o g g i n g of the Ridge and Pond zones, Wolf pr o s p e c t , c e n t r a l B r i t i s h Columbia 61 3.21 East-west v e r t i c a l s e c t i o n (D-D':Fig. 3.1A) o f the Wolf p r o s p e c t from s u r f a c e mapping and core l o g g i n g o f the Ridge and Pond zones system, Wolf p r o s p e c t , c e n t r a l B r i t i s h Columbia 62 3.22 North-south v e r t i c a l s e c t i o n (C-C':Fig. 3.1A) o f the Wolf p r o s p e c t showing d i s t r i b u t i o n o f v e i n and b r e c c i a phases wi t h depth ( r e f e r t o F i g u r e 3.20 f o r geology) 68 x v i page 3.23 East-west v e r t i c a l s e c t i o n (D-D':Fig. 3.1A) of the Wolf p r o s p e c t showing d i s t r i b u t i o n of v e i n and b r e c c i a phases with depth ( r e f e r t o F i g u r e 3.23 f o r geology) 71 3.24 Trench map of the Ridge Zone ( F i g s . 3.18 showing d i s t r i b u t i o n of g o l d and s i l v e r grades, Wolf p r o s p e c t (from Holmgren and Cann, 1985). Refer t o F i g u r e 3.19 f o r d i s t r i b u t i o n of v e i n and b r e c c i a t e x t u r e s 74 3.25 Q u a l i t i t i v e a l t e r a t i o n map of the Wolf p r o s p e c t . Zones of h i g h a r g i l l i c a l t e r a t i o n are i n d i c a t e d by hatched l i n e s ; advanced a r g i l l i c a l t e r a t i o n i s i n d i c a t e d by c r o s s h a t c h i n g . A) west h a l f , and B) e a s t h a l f 76 3.26 Scanning e l e c t r o n microscope energy d i s p e r s i v e peaks of electrum (Au, Ag) i n quartz-carbonate v e i n s of the Ridge zone ( F i g s . 3.18, 3.19 and 3.24), Wolf p r o s p e c t ...80 3.27 Scanning e l e c t r o n microscope energy d i s p e r s i v e peaks r e p r e s e n t i n g one or a combination of a g u i l a r i t e (Ag 4SeS), naummannite (Ag 2Se), or a c a n t h i t e (AgS 2) i n quartz-carbonate v e i n s of the Ridge zone ( F i g s . 3.18, 3.19 and 3.24), Wolf p r o s p e c t 84 3.28 L o g a r i t h m i c p r o b a b i l i t y p l o t s i l l u s t r a t i n g d i s t r i b u t i o n o f : A = Au, B = Ag, C = S, D = Sb, E = Ba from the Wolf p r o s p e c t . Means and standard d e v i a t i o n s are i n Table 3.9 96 3.29 L o c a t i o n s of s u r f a c e v e i n s sampled f o r f l u i d i n c l u s i o n a n a l y ses from the Wolf p r o s p e c t . A) west h a l f , and B) e a s t h a l f . Sample d e s c r i p t i o n s are i n Table 3.10.. .103 3.30 L o c a t i o n s of v e i n s sampled f o r f l u i d i n c l u s i o n a n a l y s es on s e c t i o n C-C ( F i g . 3.1), Ridge and Pond zones, Wolf prospect, c e n t r a l B r i t i s h Columbia. Sample d e s c r i p t i o n s are i n Table 3.10 ..105 3.31 E u t e c t i c and l a s t m e l t i n g temperatures of i n c l u s i o n s from bladed quartz-carbonate v e i n s from the Wolf p r o s p e c t . F r e e z i n g data are i n Table 3.12 118 3.32 E u t e c t i c and l a s t m e l t i n g temperatures of i n c l u s i o n s from drusy quartz i n f i l l i n g s from the Wolf p r o s p e c t . F r e e z i n g data are i n Table 3.12 118 x v i i page 3.33 Homogenization temperature v s . v e i n type f o r f l u i d i n c l u s i o n samples from the Wolf p r o s p e c t . Data are i n T a b l e 3.12 122 3.34 Homogenization temperature v s. o r i g i n type f o r f l u i d i n c l u s i o n samples from the Wolf p r o s p e c t . Data are i n T a b l e 3.12 123 3.35 Homogenization temperature v s. l i q u i d t o vapour r a t i o s o f primary f l u i d i n c l u s i o n s from the Wolf p r o s p e c t . Data are i n Table 3.12 12 6 3.3 6 Frequency d i s t r i b u t i o n o f volume p e r c e n t vapour i n f l u i d i n c l u s i o n s from v e i n s , Wolf p r o s p e c t , showing the wide v a r i a t i o n i n L:V r a t i o s . Data are i n Tab l e 3.12 128 3.37 Homogenization temperature v s. s a l i n i t y f o r f l u i d i n c l u s i o n s from the Wolf p r o s p e c t . Two f l u i d p o p u l a t i o n s (bars r e p r e s e n t standard e r r o r o f the means) are observed: (a) f l u i d s c h a r a c t e r i s t i c o f e a r l y formed bladed quartz-carbonate v e i n s which have h i g h e r homogenization temperatures and s a l i n i t i e s , and (b) f l u i d s c h a r a c t e r i s t i c o f l a t e drusy quartz which have lower homogenization temperatures and s a l i n i t i e s 129 3.38 Sketches i l l u s t r a t i n g p o s s i b l e h y d r o s t a t i c (A), l i t h o s t a t i c (B) or in t e r m e d i a t e (C) c o n d i t i o n s o f v e i n p r e c i p i t a t i o n a t the Wolf p r o s p e c t . Shaded area r e p r e s e n t s subsequently f i l l e d v e i n opening. Data from g o l d - b e a r i n g bladed quartz-carbonate v e i n s ( s e c t i o n 3.6.1.5) i n d i c a t e t h a t c o n d i t i o n s a l t e r a t e d between A and C a t the b o i l i n g p o i n t 131 3.39 L o c a t i o n s o f samples of whole rock, v e i n and m i n e r a l separate samples used f o r oxygen i s o t o p e a n a l y s e s from the Wolf p r o p e r t y . A)west h a l f , and B) e a s t h a l f 137 3.40 dD v s . d x o 0 v a l u e s showing f i e l d s f o r magmatic and metamorphic water and the range of d e p o s i t i o n a l f l u i d composition a t Wolf, c e n t r a l B.C. Values f o r ot h e r T e r t i a r y v o l c a n i c - h o s t e d e p i t h e r m a l d e p o s i t s i n B.C., Yukon T e r r i t o r y , and western U.S.A. are a l s o shown 150 i ft • 3.41 dD vs. d-^O f o r quartz v e i n samples from the Wolf p r o s p e c t w i t h proposed f l u i d e v o l u t i o n l i n e 152 x v i i i page 3.42 Schematic diagram i l l u s t r a t i n g Ootsa Lake Group v o l c a n i c s e t t i n g a t Wolf u s i n g a c a l d e r a c o l l a p s e model. 1 = conglomerate and t u f f s , 2 = p y r o c l a s t i c assemblage, 3 = r h y o l i t e dome, flows and b r e c c i a , and 4 = i n t r u s i o n s 154 3.43 Schematic c r o s s - s e c t i o n of low sulphur, h o t - s p r i n g type s i l i c i f i e d stockwork model f o r the g e n e s i s of the Wolf prospect, c e n t r a l B r i t i s h Columbia 157 4.1 Geology of the Capoose prospect, Capoose Lake area, c e n t r a l B r i t i s h Columbia. C r o s s - s e c t i o n s A-A' and B-B'are i n F i g u r e s 4.2 and 4.3, r e s p e c t i v e l y . . . . . . . . 164 4.2 Cross s e c t i o n A-A' ( F i g . 4.1) a c r o s s the main zone on the Capoose p r o p e r t y d e f i n i n g two n o r t h e a s t -t r e n d i n g d i p - s l i p f a u l t s which mark the boundaries of a minor h o r s t ...172 4.3 Cross s e c t i o n B-B' ( F i g . 4.1) a c r o s s the northwestern limb of the Fawnie Range s y n c l i n e showing s t r a t i g r a p h i c r e l a t i o n s h i p s . . 173 4.4 Whole rock and t r a c e element chemical a n a l y s e s sample l o c a t i o n s , Capoose p r o p e r t y , Capoose Lake area 175 4.5 L o g a r i t h m i c oxide molecular p r o p o r t i o n r a t i o p l o t s (K 20 denominator) f o r comparison of Capoose v o l c a n i c rocks t o 'modern' v o l c a n i c s u i t e s and r e t r i e v a l o f l e a s t a l t e r e d data (Beswick, 1978). Most dots which r e p r e s e n t rocks from the Capoose p r o s p e c t (Appendix IB) f a l l predominantly w i t h i n the l i m i t s f o r 'modern' v o l c a n i c s u i t e s . Least a l t e r e d rocks are i n Table 3.3 180 4.6 P l o t of a l k a l i e s v s . s i l i c a f o r analyses from the Capoose p r o p e r t y (Table 4.3, boundaries are from MacDonald, 1968, and I r v i n e and Baragar, 1971). Assemblages are s u b - a l k a l i n e ( s e c t i o n 4.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s and c i r c l e s = dykes 182 4.7 AFM diagram w i t h analyses from the Capoose p r o p e r t y (Table 4.3, boundaries are from Wager and Deer, 1939). Assemblages are c a l c - a l k a l i n e ( s e c t i o n 4.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s and c i r c l e s = dykes 183 x i x 4.8 Jensen C a t i o n p l o t f o r analyses from the Capoose p r o s p e c t (Table 4.3, boundaries are from Jensen, 1976). Assemblages are dominantly c a l c - a l k a l i n e ( s e c t i o n 4.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s , c i r c l e s = dykes 4.9 P l o t of a l k a l i e s v s. s i l i c a f o r a n alyses from the Capoose p r o p e r t y (Table 4.3, boundaries are from Le Bas e t a l . , 1986). Assemblages are ' r h y o l i t e s ' ( s e c t i o n 4.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s diamonds = v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s and c i r c l e s = dykes 186 4.10 T r i a x i a l oxide p l o t ( F e 2 0 3 + FeO + 1/2 (MgO + CaO) v s . A l 2 0 3 / S i 0 2 ) w i t h analyses from the Capoose p r o s p e c t (Table 4.3). Assemblages are ' r h y o l i t e s ' ( s e c t i o n 4.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s diamonds .= v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s and c i r c l e s = dykes 187 4.11 K 20 v s . S i 0 2 p l o t f o r a nalyses from the Capoose p r o s p e c t (Table 4.3, boundaries are from de Rosen-Spence, 1976). A b r e v i a t i o n s are: LK = low potassium, MK = medium potassium, HK = h i g h potassium, VHK = v e r y h i g h potassium, EHK = extremely h i g h potassium. R h y o l i t e s i l l s have hi g h (HK) potassium ( s e c t i o n 4.2.2) and are p l o t t e d u s i n g the f o l l o w i n g symbols: squares = mafic v o l c a n i c s , diamonds = v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s and c i r c l e s = dykes 188 4.12 L i n e graphs d e p i c t i n g calcium, magnesium, i r o n and manganese c o m p o s i t i o n a l zoning from r i m - t o - c o r e i n t h r e e brown garnet and t h r e e p i n k garnet g r a i n s from u n i t s 6, 7, and 8 ( F i g . 4.1, T a b l e 4.7). Sympathetic v a r i a t i o n i n manganese and i r o n d i f f e r s from c a l c i u m and magnesium v a r i a t i o n . Zonation i n p i n k and brown garnets i s d i s t i n c t i v e ( s e c t i o n 4.5.4.2). V e r t i c a l bars are standard d e v i a t i o n s of a n a l y s e s . A) KCP009-RIM6 brown, B) KCP012-RI18 brown, C) KCP054-R208 brown, D) KCP009-R218 pink, E) KCP012 -RI12 pink, F) KCP054-R202 pin k 206 4.13 Compositions of Capoose garnets, expressed as the end members: AL (almandine) + PY (pyrope), SP ( s p e s s a r t i n e ) , and GR ( g r o s s u l a r i t e ) + AN ( a n d r a d i t e ) , are compared wi t h the f o l l o w i n g environments: p l u t o n i c (Troger, 1959; Vennum and Meyer, 1979), v o l c a n i c (Bryant, 1975; F i t t o n , 1972; Green and Ringwood, 1968; O l i v e r , 1956; Troger, 1959; Wood, 1974), g r e e n s c h i s t (Brown, 1969; Fodor and Burt, 1979; Troger, 1959), and a m p h i b o l i t e (Miyashiro, 1953; Troger, 1959) 217 page 184 X X page 4.14 M i n e r a l i z e d zones of the Capoose Prospect, Capoose Lake area, c e n t r a l B r i t i s h Columbia 222 4.15 a) Southwest-northeast v e r t i c a l s e c t i o n (B-B':Fig. 4.1) of the Capoose prospect showing d i s t r i b u t i o n from zones 1 and 2 ( F i g 4.14) of A) s p h a l e r i t e , B) galena, C) a r s e n o p y r i t e , D) c h a l c o p y r i t e , and E) p y r i t e with depth. Refer t o F i g u r e 4.3 f o r geology..225 4.16 Q u a l i t a t i v e a l t e r a t i o n map of the Capoose p r o s p e c t . Zones of p h y l l i c a l t e r a t i o n are i n d i c a t e d by hatched l i n e s ; extreme p h y l l i c a l t e r a t i o n i s i n d i c a t e d by c r o s s h a t c h i n g 230 4.17 L o g a r i t h m i c p r o b a b i l i t y p l o t s i l l u s t r a t i n g d i s t r i b u t i o n o f A = Ag, B = Cu, C = Pb, and D = Zn from the Capoose p r o s p e c t . Means and standard d e v i a t i o n s are i n Table 4.11 241 4.18 L i n e diagram i l l u s t r a t i n g estimated p a r a g e n e s i s o f dominant s u l p h i d e s and p r e c i o u s metals a t Capoose...245 4.19 Sample l o c a t i o n s of v e i n s used f o r f l u i d i n c l u s i o n a n a l y s es from the Capoose p r o s p e c t . S e c t i o n B-B' i s l o c a t e d i n F i g u r e 4.1. Sample d e s c r i p t i o n s are i n Table 4 .15 248 4.20 E u t e c t i c and l a s t m e l t i n g temperatures o f i n c l u s i o n s from quartz and c a l c i t e v e i n s from the Capoose p r o s p e c t . F r e e z i n g data are i n Table 4.12 .254 4.21 A) Homogenization temperature v s . v e i n type, and B) homogenization temperature v s . o r i g i n type f o r f l u i d i n c l u s i o n s from quartz and c a l c i t e v e i n s from the Capoose p r o s p e c t . Data are i n Table 4.12........257 4.22 Sample l o c a t i o n s o f whole rock, v e i n and m i n e r a l separate samples used f o r s t a b l e i s o t o p e a n a l y s e s from the Capoose p r o s p e c t . See F i g u r e 4.20 f o r sample l o c a t i o n s from d r i l l core 263 4.23 dD v s . d 1 8 0 v a l u e s showing f i e l d s f o r magmatic and metamorphic water and the range of d e p o s i t i o n o f f l u i d composition a t Capoose, c e n t r a l B.C. Values f o r o t h e r w e l l known d e p o s i t s are a l s o shown 277 4.24 Low-grade, e p i g e n e t i c , i n t r u s i o n - r e l a t e d , porphyry - s t y l e model f o r ge n e s i s o f the Capoose p r o s p e c t , c e n t r a l B r i t i s h Columbia 283 x x i LIST OF PLATES page F r o n t i s p i e c e s v 3.1 Photomicrograph of broken o r t h o c l a s e and quartz c r y s t a l s t y p i c a l of Ootsa Lake Group c r y s t a l t u f f ( E o 6 ; F i g . 3.1). Sample KA133, Wolf p r o s p e c t . Tr a n s m i t t e d l i g h t , c r o s s e d p o l a r s ..18 3.2 Photomicrograph of a s p h e r u l i t e from Ootsa Lake Group r h y o l i t e ( E o 7 ; F i g . 3.1). Sample KA104, Wolf p r o s p e c t . T ransmitted l i g h t , plane p o l a r i z e d l i g h t 18 3.3 Flow banding i n Ootsa Lake Group r h y o l i t e ( E o 7 ; F i g . 3.1). Sample KA104, Wolf p r o s p e c t 19 3.4 Black chalcedony and f e l s i c v o l c a n i c fragments i n h e t e r o l i t h i c b r e c c i a ( E o g ; F i g . 3.1). Sample KA1-6, Wolf p r o s p e c t 19 3.5 Prominent euhedral quartz c r y s t a l s i n quartz porphyry ( E o 1 Q ; F i g . 3.1). Sample KA141, Wolf p r o s p e c t 23 3.6 P o o r l y c o n s o l i d a t e d mid-Miocene s i l t s t o n e and t u f f a c e o u s sandstone (Ms; F i g . 3.2). Sample KA2-10, Wolf p r o s p e c t . Discordant saw marks t o r i g h t of sample 2 3 3.7 M o n o l i t h i c quartz-cemented v o l c a n i c b r e c c i a from the Ridge zone. Sample KATR7-3, Wolf p r o s p e c t 63 3.8 Bladed carbonate i n quartz from the Ridge zone. Sample KATR9-1, Wolf prospect 63 3.9 M i l k y white quartz v e i n s as t h i c k as 2 m a t the Lookout Zone, Wolf p r o s p e c t ; 65 3.10 Drusy v e i n quartz from the East zone. Sample KA188, Wolf p r o s p e c t 65 3.11 Banded chalcedony v e i n s from the Pond zone. Sample KA4-7, Wolf prospect 67 3.12 Photomicrograph of c l e a r c r y s t a l l i n e quartz i n t e r s t i t i a l t o dark bladed carbonate, Ridge zone. Sample KATR9-1, Wolf prospect 67 3.13 Photomicrograph of electrum i n a quartz-carbonate v e i n from the Ridge zone. Sample KATR9-1, Wolf p r o s p e c t . B a c k - s c a t t e r e d e l e c t r o n image 81 x x i i page 3.14 Photomicrograph of electrum w i t h i n p y r i t e cubes i n a quartz-carbonate v e i n from the Ridge zone. Sample KATR9-1, Wolf p r o s p e c t . B a c k - s c a t t e r e d e l e c t r o n image 82 3.15 Photomicrograph of n a t i v e s i l v e r i n a q u a r t z -carbonate v e i n from the Ridge zone. Sample KATR9-1, Wolf p r o s p e c t . B a c k - s c a t t e r e d e l e c t r o n image.... 82 3.16 Photomicrograph of growth zones i n quartz d e f i n e d by primary f l u i d i n c l u s i o n c o n c e n t r a t i o n s . Quartz-carbonate v e i n from the Pond zone. Sample KA4-8, Wolf p r o s p e c t . Transmitted l i g h t , plane p o l a r i z e d l i g h t 113 3.17 Photomicrograph of planes of secondary f l u i d i n c l u s i o n s i n quartz from the Pond zone. Sample KA6-2, Wolf prospect. Transmitted l i g h t , plane p o l a r i z e d l i g h t 114 3.18 Photomicrograph of t y p i c a l two-phase f l u i d i n c l u s i o n s i n v e i n quartz from the Ridge zone. Sample KA022, Wolf p r o s p e c t . T r a n s m i t t e d l i g h t , p lane p o l a r i z e d l i g h t 114 3.19 Photomicrograph of growth zones i n a quartz c r y s t a l d e f i n e d by primary f l u i d i n c l u s i o n c o n c e n t r a t i o n s . Pond zone. Sample KA4-8, Wolf p r o s p e c t . T r a n s m i t t e d l i g h t , plane p o l a r i z e d l i g h t 116 4.1 C a l l o v i a n belemnites i n l i t h i c wacke ( u n i t 5; F i g . 4.1) of the Smithers Formation, Hazelton Group, Capoose p r o s p e c t 169 4.2 C h i l l e d c o n t a c t of quartz garnet r h y o l i t e s i l l ( u n i t 6; F i g . 4.1) adjacent t o h o r n f e l s e d a r g i l l i t e - t u f f ( u n i t 4; F i g . 4.1), Capoose p r o s p e c t 169 4.3 Photomicrograph of i n d i v i d u a l p i n k s p e s s a r t i n e i n garnet r h y o l i t e ( u n i t 7; F i g . 4.1), Sample KCP009, Capoose p r o s p e c t . Transmitted l i g h t , plane p o l a r i z e d l i g h t 19 6 4.4 Photomicrograph of aggregates of brown s p e s s a r t i n e i n r h y o l i t e ( u n i t 8; F i g . 4.1),, Sample KCP054, Capoose p r o s p e c t . Transmitted l i g h t , plane p o l a r i z e d l i g h t 196 4.5 Photomicrograph of anhedral brown s p e s s a r t i n e i n r h y o l i t e , Sample KCP044 Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , plane p o l a r i z e d l i g h t ..197 x x i i i page 4.6 Photomicrograph o f t y p i c a l s l i g h t l y a n i s o t r o p i c brown s p e s s a r t i n e i n r h y o l i t e , Sample KCP054, Capoose p r o s p e c t . Transmitted l i g h t , plane p o l a r i z e d l i g h t 197 4.7 Photomicrograph o f brown s p e s s a r t i n e without d i s t i n c t i n c l u s i o n t r a i l s . Garnet r h y o l i t e , Sample KCP012, Capoose prospect. Transmitted l i g h t , plane p o l a r i z e d l i g h t 198 4.8 Photomicrograph of brown s p e s s a r t i n e a d j a c e n t t o quartz and s u l p h i d e s (opaque) i n garnet r h y o l i t e . Sample KCP012, Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , plane p o l a r i z e d l i g h t 198 4.9 Photomicrograph o f brown s p e s s a r t i n e a d j a c e n t t o quartz c l u s t e r s i n r h y o l i t e . Sample KCP054, Capoose p r o s p e c t . Transmitted l i g h t , plane p o l a r i z e d l i g h t . . 1 9 9 4.10 Photomicrograph of brown s p e s s a r t i n e w i t h i n t e r s t i t i a l galena, zone 1, Capoose p r o s p e c t . BCMEMPR c o l l e c t i o n sample CAP-5-210. R e f l e c t e d l i g h t , plane p o l a r i z e d l i g h t 232 4.11 Photomicrograph o f p y r i t e and c h a l c o p y r i t e i n c l u s i o n s i n s p h a l e r i t e , zone 1, Capoose p r o s p e c t . BCMEMPR c o l l e c t i o n sample 79-CAP-4-504. R e f l e c t e d l i g h t , plane p o l a r i z e d l i g h t 232 4.12 Photomicrograph of c h a l c o p y r i t e e x s o l u t i o n s i n p y r i t e w i t h c o v e l l i t e , zone 1, Capoose p r o s p e c t . BCMEMPR c o l l e c t i o n sample CAP-5-434. R e f l e c t e d l i g h t , plane p o l a r i z e d l i g h t 233 4.13 Photomicrograph o f galena as ameboid b l e b s i n p y r i t e , zone 1, Capoose p r o s p e c t . BCMEMPR c o l l e c t i o n sample 79CAP-6-260. R e f l e c t e d l i g h t , plane p o l a r i z e d l i g h t 233 4.14 Photomicrograph of c h a l c o p y r i t e , p y r i t e , a r s e n o p y r i t e and galena assemblage, zone 2, Capoose p r o s p e c t . ( F i g . 4.15), BCMEMPR c o l l e c t i o n sample CAP80-39. R e f l e c t e d l i g h t , plane p o l a r i z e d l i g h t . . . . 2 3 4 4.15 Photomicrograph of brown s p e s s a r t i n e w i t h coronas of s e r i c i t e and f i n e - g r a i n e d q u a r t z . R h y o l i t e , Sample KCP001, Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t 237 4.16 Photomicrograph o f pin k s p e s s a r t i n e w i t h coronas o f s e r i c i t e and f i n e - g r a i n e d q u a r t z . Quartz garnet r h y o l i t e , Sample KCP009, Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , plane p o l a r i z e d l i g h t 237 v ACKNOWLEDGEMENTS F i e l d and f i n a n c i a l support f o r t h i s study was generously p r o v i d e d by Rio Algom E x p l o r a t i o n Inc., Vancouver, the B r i t i s h Columbia M i n i s t r y o f Energy, Mines and Petroleum Resources, Cominco L t d . and a G.R.E.A.T. Award from the B r i t i s h Columbia Science C o u n c i l . Granges E x p l o r a t i o n L t d . and Cominco L t d . are thanked f o r p e r m i s s i o n t o v i s i t the Capoose p r o p e r t y . I am s i n c e r e l y g r a t e f u l t o Dr. C o l i n Godwin f o r h i s h e l p f u l guidance, co n s t a n t support, and c o n s t r u c t i v e e d i t i n g . Dr. T.K. Kyser gave c o n s i d e r a t e l y of h i s c o n s u l t a t i o n , h o s p i t a l i t y and time; D. Pezerdec, M. Wilson and P. Honovar were extremely h e l p f u l i n the s t a b l e i s o t o p e l a b o r a t o r y i n Saskatoon. R.M. Cann i n i t i a t e d t he Wolf p r o j e c t and was always a v a i l a b l e f o r e n l i g h t e n i n g d i s c u s s i o n . D.V. Lefebure generously gave h i s time and ideas i n the f i e l d a t Capoose. I thank Dr. G. Rouse f o r a l l o w i n g access t o h i s l a b o r a t o r y and h i s perseverence with e l u s i v e palynomorphs. Dr. P. Michael and M. P i r a n i a n are thanked f o r undertaking the microprobe a n a l y s e s . Dr. J.K. R u s s e l l p r o v i d e d c a r e f u l e d i t i n g and c o n s t r u c t i v e comments. I thank B.N. Church and T.G. Sch r o e t e r f o r a l l o w i n g use of t h e i r data from the Capoose pr o s p e c t . C. S t a n l e y gave p e r m i s s i o n and advice on program PEARCE.PLOT. S p e c i a l thanks go t o T. Hoy f o r h e l p f u l d i s c u s s i o n s and a d v i c e . I am g r a t e f u l t o R. L i g h t and my f r i e n d s R. Gaba, K. Hancock, B. L a i r d and P. D e s j a r d i n s f o r t h e i r t i m e l y d r a f t i n g a s s i s t a n c e and good cheer. My f a m i l y was an encouraging and warm source of moral support. 1 CHAPTER 1 INTRODUCTION: THE CAPOOSE LAKE AREA 1.1 LOCATION AND ACCESS The Capoose Lake area i n c e n t r a l B r i t i s h Columbia i s approximately 110 km south-southeast of Burns Lake and 180 km southwest of P r i n c e George. I t i s a 30 km by 30 km area c e n t e r e d a t l a t i t u d e 53°15 / n o r t h and l o n g i t u d e 125°15 / west (N.T.S. 093/F) t h a t encompases the Wolf and Capoose p r e c i o u s metal d e p o s i t s — t h e focus of t h i s study. Access t o the area i s by h e l i c o p t e r , f l o a t plane or four-wheel d r i v e road o f f the main Kluskus-Ootsa l o g g i n g road running southwest from Vanderhoof ( F i g 1.1). 1.2 PHYSIOGRAPHY The Capoose Lake map area i s w i t h i n the Nechako P l a t e a u of c e n t r a l B r i t i s h Columbia. Topography i s c h a r a c t e r i z e d by groups of low, rounded h i l l s and broad v a l l e y s . Although mountainous areas, such as the Fawnie Range, reach e l e v a t i o n s of 1,900 m, l o c a l r e l i e f r a r e l y exceeds 700 m above an average e l e v a t i o n of 1200 m. T r e e l i n e roughly f o l l o w s the 1,600 m contour, hence approximately 90% of the area i s t r e e covered. V e g e t a t i o n i s predominantly lodgepole pine, w i t h moderate undergrowth. Most f l a t l y i n g areas are covered w i t h swamps, and abundant growth of t a l l grasses and low brush. Rock drumlins, produced by major i c e advance i n c e n t r a l B r i t i s h Columbia (Tipper, 1963), have a pronounced 030° FIGURE 1.1: L o c a t i o n of the Wolf and Capoose p r o s p e c t s , Capoose Lake area, c e n t r a l B r i t i s h Columbia. 3 o r i e n t a t i o n as seen on a e r i a l photographs. However, on some of the h i g h e r h i l l s , such as the Fawnie Range, g l a c i a l s t r i a e t r e n d 060°. T h i s i n d i c a t e s , as T i p p e r (1963) suggests, a southwestern source f o r the i c e . 1.3 PREVIOUS WORK AND EXPLORATION HISTORY D e t a i l e d g e o l o g i c mapping and e x p l o r a t i o n i n the Capoose Lake area have been hindered by e x t e n s i v e overburden and c o s t l y l i m i t e d access. Recent l o g g i n g a c t i v i t y on the Kluskus-Ootsa road has f a c i l i t a t e d c o n s t r u c t i o n o f mining roads which have opened up the area. E a r l i e s t r e g i o n a l g e o l o g i c mapping i n the area was by T i p p e r (1963) d u r i n g the f i e l d seasons of 1949 t o 1952. No othe r r e g i o n a l g e o l o g i c surveys have been p u b l i s h e d f o r t h i s area. S i g n i f i c a n t m i n e r a l e x p l o r a t i o n i n the Capoose Lake area began p r i o r t o 1969 when Rio T i n t o Canadian E x p l o r a t i o n L t d . began a s y s t e m a t i c l a k e sampling program. The Capoose p r o p e r t y covers a geochemical anomaly d i s c o v e r e d as a r e s u l t o f t h i s program. RioCanex worked on the p r o p e r t y between 1969 and 1971. E x p l o r a t i o n from 1976 t o 1985 by Granges E x p l o r a t i o n L t d . , i n j o i n t venture w i t h Bethlehem Copper Corp. and l a t e r w i t h Cominco L t d . , has i n c l u d e d diamond d r i l l i n g t o t a l l i n g 13,285 m i n 85 h o l e s . In 1982 Rio Algom E x p l o r a t i o n Inc. conducted another l a k e sediment survey i n c e n t r a l B.C. Sediment r e l a t e d t o the Wolf p r o p e r t y was found t o be anomalous i n s i l v e r . Work by Rio Algom from 4 1982 t o 1985 has i n c l u d e d e x t e n s i v e t r e n c h i n g of s i l i c i f i e d and b r e c c i a t e d zones as w e l l as diamond d r i l l i n g t o t a l l i n g 593 m i n 6 h o l e s . S e v e r a l s t u d i e s have been undertaken i n the Capoose Lake area. Hoffman (1976) and Gi n t a u t a s (1984) d i s c u s s e d m i n e r a l e x p l o r a t i o n and l a k e sediment geochemistry i n the Nechako P l a t e a u of c e n t r a l B r i t i s h Columbia. S c h r o e t e r (1981) and Church and Diakow (1982) p r e s e n t overview geology and l i t h o g e o c h e m i s t r y of the Capoose p r o s p e c t ; however, no d e t a i l e d mapping s t u d i e s have been undertaken i n the area by the above. 1.4 OBJECTIVES The f i e l d and l a b o r a t o r y study of the Wolf and Capoose p r o s p e c t s i n the Capoose Lake area has the f o l l o w i n g f i e l d o b j e c t i v e s (A), l a b o r a t o r y o b j e c t i v e s (B), and t h e o r e t i c a l c o n t r i b u t i o n s (C): (Al) t o p r o v i d e d e t a i l e d mapping of the p o o r l y understood Ootsa Lake Group v o l c a n i c s t r a t i g r a p h y i n the v i c i n i t y o f the Wolf prospect, (A2) t o map i n d e t a i l Hazelton Group s t r a t i g r a p h y i n the v i c i n i t y o f the Capoose d e p o s i t , and t o c o r r e l a t e i t with known s t r a t i g r a p h y t o the northwest, (Bl) t o determine the p e t r o l o g i c and chemical c h a r a c t e r i s t i c s o f v o l c a n i c s t r a t i g r a p h y i n the Capoose Lake area, 5 (B2) t o p r o v i d e an o r i g i n f o r the g a r n e t - b e a r i n g r h y o l i t e s i l l s which are a s s o c i a t e d with the Capoose pro s p e c t , (B3) t o d e f i n e the s t y l e and t i m i n g of m i n e r a l i z a t i o n i n the Capoose Lake area, (CI) t o prese n t a model f o r the hydrothermal environment of d e p o s i t i o n f o r both the Wolf and the Capoose p r o s p e c t s u s i n g f l u i d i n c l u s i o n and oxygen i s o t o p e data, (C2) t o develop a model f o r the genesis of the p r o s p e c t s and of any p o t e n t i a l r e l a t i o n s h i p they may have t o each other, and (C3) t o compare the pr o s p e c t s with o t h e r s i m i l a r , w e l l -d e s c r i b e d d e p o s i t s i n the C o r d i l l e r a . 6 CHAPTER 2 REGIONAL GEOLOGY 2.1 TECTONIC SETTING The Wolf and Capoose p r o s p e c t s are w i t h i n the a l l o c h t h o n o u s oceanic a r c t e r r a n e of S t i k i n i a (Monger e t a l . , 1982) i n the Intermontane B e l t ( i n s e t , F i g . 2.1). S t i k i n i a has a basement of Upper P a l e o z o i c submarine a r c rocks o v e r l a i n by Upper T r i a s s i c t o Middle J u r a s s i c submarine and s u b a e r i a l v o l c a n i c and sedimentary rocks (Takla-Hazelton assemblage) t h a t have been i n t r u d e d by c o e v a l g r a n i t i c p l u t o n s (Coney e t a l . , 1980). S t i k i n i a rocks are s i m i l a r i n composition t o rocks found a t a c t i v e v o l c a n i c a r c s such as the A l e u t i a n I s l a n d s i n A l a s k a (Jones e t a l . , 1983), hence, the t e r r a n e i s thought t o have a r c a f f i n i t y (Davis e t a l , 1978). Terranes of the Intermontane B e l t — E a s t e r n , Q u e s n e l l i a , Cache Creek and S t i k i n i a — f o r m e d a l a r g e composite t e r r a n e i n l a t e s t T r i a s s i c t o E a r l y J u r a s s i c time (Monger and P r i c e , 1979) p r i o r t o a c c r e t i o n t o the a n c i e n t margin of North America by m i d - J u r a s s i c time. Monger and I r v i n e (1980) suggested t h a t S t i k i n i a then moved 1,300 km northwards along the western f r i n g e of North America t o i t s p r e s e n t p o s i t i o n i n Late Cretaceous or E a r l y T e r t i a r y time. 7 INDEX MAP A A A A V V V V SUPERTERRANE I: EASTERN TERRANE QUESNELLIA TERRANE CACHE CREEK TERRANE STIKINA TERRANE Terrane boundary V V V V V Sv w w v f v v v v v v v B - V V V V V V V V - V V V V V V V i V V V V V V V y V V v v v v ' W W W / w w w • M P v b V V V v v v v v w i V v W V v v V V V V V W / w w w w w w ^rS3*i5v v w w w w w w w w w Emiakov. v Lake v w v, v v v , v / ^ « r e o . M • %» G e o l o g i c a l boundary F a u l t , assumed LEGEND TERTIARY MIOCENE and PLIOCENE [MPvi>piivine b a s a l t flows, b r e c c i a , t u f f | Eol |Ootsa Lake Group Rh y o l i t e , d a c i t e , t r a c h y t e , sandstone shale, conglomerate CRETACEOUS and/or TERTIARY | K g u |Quanchus I n t r u s i o n s G r a n o d i o r i t e , quartz d i o r i t e , d i o r i t e , g r a n i t e | K r s u|Garnet r h y o l i t e s i l l s JURASSIC MIDDLE JURASSIC 1 j h v m|Hazelton Group P a r t l y undivided; b a s a l t , andesite, t u f f , b r e c c i a , greywacke, raudstone, conglomerate LOWER JURASSIC | J h v i |Hazelton Group A n d e s i t i c to r h y o l i t i c t u f f , b r e c c i a , flows, sediments FIGURE 2.1: D i s t r i b u t i o n o f major g e o l o g i c a l groups, Capoose Lake area ( a f t e r T i p p e r , 1963; T i p p e r e t a l . , 1979). Inset map: L o c a t i o n o f the Capoose Lake area w i t h r e s p e c t to C o r d i l l e r a n T e c t o n i c B e l t s (from Monger e t a l . , 1982). 8 2.2 GEOLOGY OF THE CAPOOSE LAKE AREA D i s t r i b u t i o n of major g e o l o g i c u n i t s i n the Capoose Lake area i s shown on F i g u r e 2.1. These are: ( u n i t 1) Lower J u r a s s i c Hazelton Group, ( u n i t 2) Middle J u r a s s i c H azelton Group, ( u n i t 3) Upper Cretaceous Quanchus I n t r u s i o n s , ( u n i t 4) Upper Cretaceous r h y o l i t e s i l l s , ( u n i t 5) Eocene Ootsa Lake Group, and ( u n i t 6) Miocene and P l i o c e n e o l i v i n e b a s a l t flows, b r e c c i a , and t u f f s ( a f t e r T i p p e r e t a l . , 1979). C o r r e l a t i o n s between groups and formations are presented i n Table 2.1. The J u r a s s i c Hazelton Group ( u n i t s 1 and 2: Leach, 1910; Hanson, 1925; Armstrong, 1944; T i p p e r , 1959 and 1971; T i p p e r and Richards, 1976) i s a r e a l l y the most e x t e n s i v e i n the Capoose Lake area. I t c o n s i s t s mainly of sedimentary rocks and f o l d e d a n d e s i t i c t o r h y o l i t i c v o l c a n i c rocks which probably r e p r e s e n t a Lower t o Middle J u r a s s i c v o l c a n i c i s l a n d a r c . The Upper Cretaceous Quanchus I n t r u s i o n s comprise two quartz monzonite p l u t o n s ( u n i t 3) and 500 m t h i c k g a r n e t i f e r o u s r h y o l i t e s i l l s ( u n i t 4). Both i n t r u d e Hazelton Group rocks i n Upper Cretaceous time. C l o s e s p a t i a l and temporal r e l a t i o n s h i p s between these i n t r u s i v e rocks suggest t h a t they c o u l d be comagmatic. Eocene Ootsa Lake group rocks ( u n i t 5: D u f f e l , 1959; T i p p e r , 1963) are p r i m a r i l y f e l s i c v o l c a n i c flows and t u f f s . These unconformably o v e r l y Hazelton Group rocks i n the Capoose Lake area. The Eocene v o l c a n i s m i n c e n t r a l B r i t i s h TABLE 2.1: C o r r e l a t i o n among major g e o l o g i c a l groups and formations from the Capoose Lake area (NTS:093F), W h i t e s a i l Lake area (NTS:093E), Smithers area (NTS:093L), Gang ranch-Big bar area (NTS:0920) CAPOOSE LAKE AREA (Tipper 1963:, Tipper et al. 1979; this study) WHITESAIL LAKE AREA (Duffel 1959, Diakow and Mihalynuk 1987; Diakow and Koyanagi 1988) SMITHERS AREA (Tipper and Richards 1976; Maclntyre and Desjardins 1988) GANG RANCH - BIG BAR AREA (Tipper 1978; Mathews and Rouse 1984) PERIOD EPOCH AGE GROUP FORMATION GROUP FORMATION GROUP FORMATION GROUP FORMATION QUATER-NARY HOLOCENE PLEISTOCENE TERTIARY PLIOCENE unnamed basalt unnamed basalt TERTIARY L MIOCENE M F^R^ SER"BENO TERTIARY FRASER BEND TERTIARY E TERTIARY L O L I G O C E N E — "Blackdome Mtn basalt' TERTIARY ENDAKO "Porcupine Ck obsidian' TERTIARY L E O C E N E M BARTONIAN TERTIARY TERTIARY LUTETIAN OOTSA LAKE OOTSA LAKE KAMLOOPS TERTIARY E TERTIARY L P A L E O C E N E Y CRETACEOUS LATE MAASTRICHTIAN unnamed rhyolite KASALKA KASALKA CRETACEOUS CAMPANIAN SANTONIAN CONIACIAN QUANCHUS II gTRUSIONS CRETACEOUS TURONIAN CENOMANIAN SPENCES BRIDGE/ KINGSVALE CRETACEOUS EARLY SKEENA SKEENA RED ROSE JACKASS MTN JURASSIC LATE ASHMAN JURASSIC BOWSER LAKE ASHMAN JURASSIC MIDDLE CALLOVIAN SMITHERS BOWSER LAKE JURASSIC BATHONIAN BAJOCIAN AALENIAN M i JURASSIC L l * ~r r~ i T /—\ l SMITHERS HAZELTON SMITHERS JURASSIC EARLY TOARCIAN PLIENSBACHIAN SINEMURIAN L NILKITKWA HAZELTON JURASSIC NILKITKWA JURASSIC TELKWA TELKWA JURASSIC HETTANGIAN 10 Columbia was widespread but of s h o r t d u r a t i o n (Nelson, 1985). CHAPTER 3 THE WOLF PRECIOUS METAL EPITHERMAL PROSPECT:  GEOLOGY AND GENESIS 3.1 LOCATION AND ACCESS The Wolf epithermal p r e c i o u s metal v e i n p r o s p e c t ( F i g 1.1) i s near l a t i t u d e 53°12 / n o r t h and l o n g i t u d e 125°26' west (N.T.S.: 93F/03) i n c e n t r a l B r i t i s h Columbia, about 6 k i l o m e t r e s southeast of Ent i a k o Lake and approximately 185 k i l o m e t r e s southwest of P r i n c e George. Access i s by h e l i c o p t e r , f l o a t plane or four-wheel d r i v e road o f f k i l o m e t r e 141 on the main Kluskus-Ootsa l o g g i n g road running southwest from Vanderhoof. 3.2 GEOLOGY 3.2.1 INTRODUCTION The Wolf prospect i s w i t h i n Ootsa Lake Group v o l c a n i c rocks ( F i g 2.1) i n an area c h a r a c t e r i s e d by approximately 1% rock outcrop. These predominantly f e l s i c v o l c a n i c r o c k s are ass i g n e d t o the r h y o l i t e member of the Eocene Ootsa Lake Group (Tipper, 1963) which unconformably o v e r l i e s J u r a s s i c H a zelton Group rocks i n the Capoose Lake area. The Ootsa Lake Group i s unconformably o v e r l a i n by mid-Miocene u n c o n s o l i d a t e d sedimentary rocks (Rouse, p e r s . comm., 1988). 3.2.2 STRATIGRAPHY AND PETROLOGY The Ootsa Lake Group r h y o l i t e member i s composed predominantly o f f e l s i c v o l c a n i c and v o l c a n i c l a s t i c rocks ( a f t e r T i p p e r , 1963). I n t r u s i v e i n t o these rocks are r h y o l i t e domes with a s s o c i a t e d flows and b r e c c i a s as w e l l as p o r p h y r i t i c plugs and dykes. F i e l d r e l a t i o n s and p e t r o l o g i c o b s e r v a t i o n s d e f i n e 10 u n i t s a t a map s c a l e of 1:5000 w i t h i n the r h y o l i t e member of the Ootsa Lake Group. These are shown on F i g u r e 3.1 and d e s c r i b e d below. Map u n i t s on the p r o p e r t y are grouped i n t o f o u r assemblages (Table 3.1) based on s p a t i a l r e l a t i o n s h i p s , s i m i l a r i t y of d e p o s i t i o n a l environment, complementary l i t h o l o g i e s and a s s o c i a t e d t e x t u r e s . The assemblages, from o l d e s t t o youngest, are: (1) conglomerate and t u f f s ( E o 1 and E 0 2 ) , (2) p y r o c l a s t i c s and subordinate flows ( E 0 3 t o E o 6 ) , (3) r h y o l i t e flows and b r e c c i a s ( E o 7 and E o 8 ) , and (4) i n t r u s i o n s ( E o 9 and E o l 0 ) . U n i t s are c o r r e l a t e d , where p o s s i b l e , w i t h Ootsa Lake Group s u b d i v i s i o n s of Diakow and Mihalynuk (1987) i n the W h i t e s a i l Lake area. Conglomerate and t u f f s ( E o 1 and Eo 2) crop out i n a creek and along a r i d g e on the northwest s i d e of the p r o p e r t y ( F i g . 3.1). Boulder conglomerate ( E o ^ i s a m a t r i x supported b a s a l u n i t with 30% well-rounded g r a n o d i o r i t e c l a s t s (5 cm t o 0.5 m i n diameter), 10% angular a n d e s i t e c l a s t s (up t o 15 cm i n diameter), and 5% subrounded a p l i t e c l a s t s (20 t o 30 cm i n diameter). The t u f f a c e o u s m a t r i x has up t o 60% q u a r t z . Although p a r t l y d e r i v e d from v o l c a n i c rocks, the quartzose matrix, and g r a n o d i o r i t e and a p l i t e c l a s t s i n d i c a t e a dominantly g r a n i t i c provenance. T h i s u n i t 13 -53°I2 N 53-irN I25°30 W L E G E N D WEST HALF ~~1 SILTS TONE MS TUFFACEOUS 1 SANDSTONE E04 A S H . T U F F EOa VOLCANIC BRECCIA EOi CONGLOMERATE EOs RHYOLITE FLOWS EOg RHYLITE PORPHYRY E 0 2 FELSIC LAPILLI TUFF E O s CRYSTAL TUFF EO10 I QUARTZ PORPHYRY E 0 3 LITHIC, CRYSTAL TUFF] EO7 | RHYOLITE Jha ANDESITE FLOWS, FLOW BRECCIA S Y M B O L S 7D geological contact: known,assumed fault:known, assumed foliation 10 hneation vein, with dip FIGURE 3.1: Geology of the Wolf pr o s p e c t , Capoose Lake area, c e n t r a l B r i t i s h Columbia. S e c t i o n s A-A', B-B', C-C and D-D' are i n F i g u r e s 3.2, 3.3, 3.20 and 3.21, r e s p e c t i v e l y . 14 -53°I2N 53°ll N EAST HALF L E G E N D ,. SI IIS TONE, Ms TUFFACEOUS 1 SANDSTONE E04 A S H . T U F F EOe VOLCANIC BRECCIA EOi ' CONGLOMERATE EOs R H Y O L I T E F L O W S E 0 9 R H Y L I T E P O R P H Y R Y E 0 2 FELSIC LAPILLI TUFF E 0 6 CRYSTAL T U F F E O 3 L I T H I C , C R Y S T A L T U F T £ E O t | R H Y O L I T E E Q I 0 | Q U A R T Z P O R P H Y R Y A N D E S I T E F L O W S , Jha F L O W BRECCIA S Y M B O L S geological contact; Known,assumed wtow/t V* v>vsi fault;Known, assumed foliation 3 ^ lineation vein, wi th dip FIGURE 3.1: Geology of the Wolf p r o s p e c t , Capoose Lake area, c e n t r a l B r i t i s h Columbia. S e c t i o n s A-A', B-B', C-C and D-D' are i n F i g u r e s 3.2, 3.3, 3.20 and 3.21, r e s p e c t i v e l y . 15 TABLE 3.1: Grouping of Ootsa Lake Group map u n i t s based on s p a t i a l r e l a t i o n s h i p , complementary l i t h o l o g y , s i m i l a r i t y o f d e p o s i t i o n a l environment, and a s s o c i a t e d t e x t u r e s , Wolf pr o s p e c t , c e n t r a l B r i t i s h Columbia. MAP UNIT LITHOLOGY TEXTURES DEPOSITIONAL ASSEMBLAGE ENVIRONMENT E o l conglomerate boulder c l a s t s f l u v i a l conglomerate and t u f f s Eo2 r h y o d a c i t e l a p i l l i t u f f 20% l i t h i c fragments s u b a e r i a l conglomerate and t u f f s Eo3 l i t h i c c r y s t a l t u f f 25% l i t h i c fragments s u b a e r i a l p y r o c l a s t i c r o c k s Eo4 ash t u f f a p h a n i t i c , m i c r o s p h e r u l i t i c s u b a e r i a l i p y r o c l a s t i c r o c k s Eo5 r h y o l i t e flows massive, a p h a n i t i c s u b a e r i a l s u b o r d i n a t e flows Eo6 c r y s t a l t u f f p o r p h y r i t i c s u b a e r i a l p y r o c l a s t i c rocks Eo7 r h y o l i t e flow banding s p h e r u l i t i c s u b a e r i a l r h y o l i t e flows and b r e c c i a s Eo8 v o l c a n i c 35% l i t h i c fragments s u b a e r i a l r h y o l i t e flows and b r e c c i a s Eo9 r h y o l i t e porphyry p o r p h y r i t i c - i n t r u s i o n s EolO quartz porphyry p o r p h y r i t i c — i n t r u s i o n s c o u l d r e p r e s e n t the b a s a l conglomerate, r e p o r t e d by D u f f e l (1959), which marks the unconformity w i t h J u r a s s i c H azelton Group r o c k s . (The type s e c t i o n d e s c r i b e d by D u f f e l (1959) on the e a s t e r n shores o f W h i t e s a i l Lake i s now submerged.) Pale green t o grey r h y o d a c i t e l a p i l l i t u f f ( E o 2 ) , r e s t s conformably on the conglomerate. The f i n e ash t u f f groundmass of t h i s u n i t supports up t o 20% p y r o c l a s t s (1 t o 10 mm i n s i z e ) . Most of the fragments are a c c i d e n t a l w i t h a v a r i e t y o f compositions. Less than 5% of the fragments are cognate, d e r i v e d from p r e v i o u s e r u p t i o n s o f the same vol c a n o . Pyroclastics and subordinate flows (Eo 3 to Eo 6) crop out over much of the w e s t - c e n t r a l p a r t o f the p r o p e r t y ( F i g . 3.1). These are predominantly l a p i l l i and ash t u f f s w i t h p y r o c l a s t s of cognate o r i g i n where a s s o c i a t e d w i t h minor flows. Grey t o green l i t h i c c r y s t a l t u f f ( E o 3 ) , forms the b a s a l u n i t o f the s h a l l o w l y westward d i p p i n g p y r o c l a s t i c sequence. T h i s t u f f has an a p h a n i t i c groundmass t h a t supports 10% quartz and s a n i d i n e c r y s t a l s , and 25% l i t h i c fragments. Textures i n the t u f f v a r y from flow-banded t o agglome r a t i c . Cream ash t u f f ( E o 4 ) . conformably o v e r l y i n g u n i t 4, i s a p h a n i t i c w i t h up t o 20% m i c r o s p h e r u l i t e s , but l o c a l l y c o n t a i n s 2 t o 5% broken quartz phenocrysts 1 mm a c r o s s . Columnar j o i n t e d , mauve r h v o l i t i c flows ( E o 5 ) . are v o l u m e t r i c a l l y subordinate t o the p y r o c l a s t i c s . The flows have a pronounced slabby p a r t i n g developed p a r a l l e l t o flow l a y e r i n g . Quartz and s a n i d i n e phenocrysts, each up t o 5% of the o v e r a l l volume, are suspended i n a f e l s i c c r y p t o c r y s t a l l i n e groundmass. Grey t o maroon c r y s t a l t u f f  f E o 6 ) . marks the top of the p y r o c l a s t i c package. I t i s c h a r a c t e r i s e d by a 'crowded' phenocryst assemblage ( P l a t e 3.1) of 30% euhedral s a n i d i n e (1 t o 3 mm across) and 10% broken quartz (1 mm i n diameter). Rhyolite flows and breccias (Eo 7 and Eo 8) crop out over most of the northern p a r t of the map area ( F i g . 3.1). R h y o l i t e ( E o 7 ) , i s commonly flow banded ( P l a t e 3.2) and s p h e r u l i t i c ( P l a t e 3.3) and unconformably o v e r l i e s u n i t s 1 t o 6 ( F i g . 3.2). The rock g e n e r a l l y c o n t a i n s 10% anhedral s a n i d i n e phenocrysts (1 t o 2 mm i n diameter) and 5% i r r e g u l a r quartz c r y s t a l s (1 mm i n d i a m e t e r ) . V o l c a n i c  b r e c c i a ( E o Q ) . occurs as s m a l l i r r e g u l a r and pod-shaped bodies w i t h i n E o 7 . T h i s b r e c c i a c o n s i s t s of 35% a c c i d e n t a l l i t h i c fragments of v a r y i n g s i z e s , and of 5% subhedral o r t h o c l a s e c r y s t a l s suspended i n an a p h a n i t i c b l a c k m a t r i x ( P l a t e 3.4). E o 7 and E o Q are t e n t a t i v e l y c o r r e l a t e d w i t h r h y o l i t i c flows of Diakow and Mihalynuk (1987: t h e i r u n i t 8) . However, Diakow and Mihalynuk make no mention of h e t e r o l i t h i c b r e c c i a . Intrusions (Eo 9 and Eo 1 0) crop out over most of the southern p a r t of the p r o p e r t y ( F i g . 3.1). Coarse g r a i n e d r h y o l i t e porphyry (Eog) c o n t a i n s up t o 60% euhedral o r t h o c l a s e and 10% quartz phenocrysts. Quartz porphyry  ( E o 1 Q ) occurs w i t h i n E o g , but i s d i s t i n g u i s h e d from i t by up t o 10% stubby, commonly embayed, quartz phenocrysts, and up 1 8 PLATE 3.1: Photomicrograph o f broken o r t h o c l a s e and q u a r t z c r y s t a l s t y p i c a l o f Ootsa Lake Group c r y s t a l t u f f ( E o 6 ; F i g . 3.1). Sample KA133, Wolf p r o s p e c t . T r a n s m i t t e d l i g h t , c r o s s e d p o l a r s . PLATE 3.2: Photomicrograph o f a s p h e r u l i t e from O o t s a Lake Group r h y o l i t e ( E o ? ; F i g . 3.1). Sample KA104, Wolf p r o s p e c t T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . 19 PLATE 3.4: B l a c k c h a l c e d o n y and f e l s i c v o l c a n i c fragments i n h e t e r o l i t h i c b r e c c i a ( E o g ; F i g . 3.1). Sample KA1-11, Wolf p r o s p e c t . t o 3% euhedral o r t h o c l a s e phenocrysts ( P l a t e 3.5). T h i s u n i t might r e p r e s e n t a l a t e magmatic stage o f the p l u t o n i s m which formed E o g . J u r a s s i c Hazelton Group Andesite flows are r e s t r i c t e d t o the e a s t e r n edge of the p r o p e r t y ( F i g . 3.1). They are dark green t o blac k , amygdaloidal, and mainly p l a g i o c l a s e p o r p h y r i t i c w i t h minor massive and b r e c c i a t e d t e x t u r e s . The matr i x i s f e l t e d and comprises 50 t o 60% p l a g i o c l a s e l a t h s . The phenocryst assemblage c o n s i s t s o f 5 t o 25% anhedral c h l o r i t i z e d a u g i t e , 5 t o 10% euhedral p l a g i o c l a s e ( A n 7 5 _ 8 2 ) , and 2 t o 10% opaques. Amygdales are i n f i l l e d w i t h c a l c i t e and agate. These rocks appear t o c o r r e l a t e w i t h the K o t s i n e subaqueous f a c i e s amygdaloidal b a s a l t flows and b r e c c i a s of T i p p e r and Richards (1976). Mid-Miocene e p i c l a s t i c rocks (Rouse, p e r s . comm., 1988) do not outcrop i n the Wolf area ( F i g . 3.1); however, these r e c e s s i v e weathering rocks occur i n d r i l l c o r e . D r i l l h o l e s on the c e n t r a l r i d g e o f the p r o p e r t y ( F i g . 3.2) encountered e p i c l a s t i c rocks a t l e a s t 30 metres t h i c k ( F i g . 3.3) composed of s i l t s t o n e , t u f f a c e o u s sandstone, coarse ash t u f f , l i t h i c t u f f and t u f f a c e o u s b r e c c i a ( P l a t e 3.6). The d e p o s i t s are p o o r l y c o n s o l i d a t e d and p o o r l y s o r t e d . Graded bedding, cross-bedding, scour marks, angular h e t e r o l i t h i c fragments, and broken quartz and f e l d s p a r c r y s t a l s w i t h corroded rims are common t e x t u r e s . 21 EOg V DDH85004 E 0 9 DDH85^ 06 1 1 1 1 1—I W O L F P R O S P E C T RIDGE AND POND ZONES DRILLHOLE- PLAN VIEW 0 25 50 METRES FIGURE 3.2: Diamond d r i l l h o l e p l a n o f the Wolf p r o s p e c t , c e n t r a l B r i t i s h Columbia. Map i s keyed t o F i g u r e 3.1A. NW SE E04 A S H T U F F EOs I— 1 SANDSTONE | EOl | C O N G L O M E R A T E | E 0 2 I FELSIC LAPILLI T U F F | E 0 6 | C R Y S T A L T U F F LITHIC,CRYSTAL TUFF["E07 | R H Y O L I T E E 0 6 VOLCANIC BRECCIA RHYOLITE FLOWS E 0 9 R H Y L I T E PORPHYRY EOio Q U A R T Z PORPHYRY E O S Jha A N D E S I T E FLOWS, FLOW B R E C C I A SYMBOLS 9 geological contact ; known,assumed M M faulr.known, assumed foliation 3* l ineat ion vein, with dip FIGURE 3.3: Cross s e c t i o n A-A' across the c e n t r a l r i d g e on the Wolf prospect ( F i g . 3.1A) showing mid-Eocene Ootsa Lake Group rocks t h r u s t over mid-Miocene e p i c l a s t i c rocks. 2 3 PLATE 3.6: P o o r l y c o n s o l i d a t e d mid-Miocene s i l t s t o n e and t u f f a c e o u s sandstone (Ms; F i g . 3 . 2 ) . Sample KA5-10, Wolf p r o s p e c t . D i s c o r d a n t saw mark t o r i g h t o f sample. 3.2.3 STRUCTURE Mesozoic and Cenozoic s t r a t a are e x t e n s i v e l y b l o c k -f a u l t e d i n the Nechako P l a t e a u (Diakow and Koyanagi, 1988). Ootsa Lake Group rocks c h a r a c t e r i s t i c a l l y are warped g e n t l y and p r e s e r v e d as open f o l d s w i t h d i p s l e s s than 45 degrees (Tipper, 1963; Diakow and Mihalynuk, 1986). Although the deformation of these rocks i s not g e n e r a l l y i n t e n s e , T i p p e r (1963) suggested t h a t commonly f e a t u r e l e s s v o l c a n i c rocks c o u l d mask complex f o l d p a t t e r n s . The s c a r c i t y of w e l l -exposed rock and the minimal s t r u c t u r a l i n f o r m a t i o n observable i n outcrops makes s t r u c t u r a l i n t e r p r e t a t i o n s d i f f i c u l t . Ootsa Lake Group rocks i n the Wolf area, however, appear t o be l i t t l e d i s t u r b e d . Bedding measurements i n d r i l l core on the Ridge zone ( F i g . 3.4) suggests f l a t l y i n g u n i t s are d i s r u p t e d o n l y s l i g h t l y by i n t r u s i o n of r h y o l i t e porphyry and by b l o c k f a u l t i n g . Measurement of columnar j o i n t i n g i n flow u n i t s i n the southwestern p a r t of F i g u r e 3.3 i n d i c a t e s s h a l l o w l y westward d i p p i n g s t r a t a . Flow banding i s i r r e g u l a r . Mid-Eocene t e c t o n i c a l l y o v e r l i e s mid-Miocene s t r a t i g r a p h y a t Wolf p o s s i b l y by low angle n o r t h - s o u t h t h r u s t i n g ( F i g s . 3.1, 3.3 and 3.4). S i m i l a r displacements are noted i n the Kenney Dam area by Rouse (pers. comm., 1988) . The r i d g e zone f a u l t i s c h a r a c t e r i z e d by i n t e n s e s h e a r i n g and gouge i n d r i l l c o r e. Displacement on t h i s Metres above sea level SW 1250 120 0-I ISO -110 0" / / / E 0 9 ECs I '*/ // E 0 5 • / / • E 0 9 N E Metres above seo level 1200 LEGEND Ms | TUFFACEOUS SANDSTONE E04 ASH TUFF EOe VOLCANIC BRECCIA EOl CONGLOMERATE EOs RHYOLITE FLOWS E 0 9 RHYLITE PORPHYRY E 0 2 FELSIC LAPILLI TUFF E 0 6 CRYSTAL TUFF E 0 , o QUARTZ PORPHYRY E 0 3 LITHIC,CRYSTAL TUFFJ E 0 7 | RHYOLITE | Jha | ANDESITE FLOWS, FLOW BRECCIA SYMBOLS geological contact; known,assumed Vtvyn «* fault;known, assumed foliation lineation vein, with dip FIGURE 3.4: Cross s e c t i o n B-B' across the southwestern p o r t i o n o f the Wolf prospect ( F i g . 3.1A) showing s t r a t i g r a p h i c r e l a t i o n s h i p s . to Ul f a u l t i s obscure because of e x t e n s i v e d r i f t and poor s t r a t i g r a p h i c i n f o r m a t i o n . 3.2.4 METAMORPHISM Low grade r e g i o n a l g r e e n s c h i s t metamorphism c h a r a c t e r i s e s rocks of the Nechako P l a t e a u . J u r a s s i c mafic v o l c a n i c rocks on the e a s t s i d e of the Wolf p r o p e r t y ( F i g . 3.1) show breakdown of primary pyroxene t o amphibole and c h l o r i t e . However, Eocene f e l s i c v o l c a n i c rocks appear t o be r e l a t i v e l y f r e s h w i t h v i r t u a l l y no s a u s s u r i t i z a t i o n of p l a g i o c l a s e . Although the deformation of these rocks i s not g e n e r a l l y i n t e n s e , T i p p e r (1963) suggested t h a t commonly f e a t u r e l e s s v o l c a n i c rocks c o u l d mask complex f o l d p a t t e r n s . 3.3 PETROCHEMISTRY Twenty-eight rock samples from the Wolf p r o p e r t y were analysed f o r major, minor and t r a c e element c o n c e n t r a t i o n s . Sample l o c a t i o n s are p l o t t e d i n F i g u r e 3.5 and p e t r o g r a p h i c d e s c r i p t i o n s are found i n Appendix 1A. 3.3.1. SAMPLE PREPARATION AND ANALYSIS A l l rock samples were broken t o c h i p - s i z e i n a jaw c r u s h e r , s p l i t and p u l v e r i z e d t o <200 mesh i n a tungsten c a r b i d e r i n g m i l l . Approximately 100 g of sample was sent t o Maurette Resources and S e r v i c e s L t d . , Calgary, A l b e r t a , f o r X-ray f l u o r e s c e n c e (XRF) a t Midland E a r t h S c i e n c e A s s o c i a t e s , Nottingham, U.K. 27 W E S T H A L F FIGURE 3.5: Sample l o c a t i o n s f o r whole rock and t r a c e element chemical analyses and X-ray d i f f r a c t i o n a n a l y s e s , Wolf pr o s p e c t , c e n t r a l B r i t i s h Columbia. A) west h a l f , and B) e a s t h a l f . 28 v \s s s <r * EAST HALF FIGURE 3.5: Sample l o c a t i o n s f o r whole rock and t r a c e element chemical a n a l y s e s and X-ray d i f f r a c t i o n a n a l y s e s , Wolf p r o s p e c t , c e n t r a l B r i t i s h Columbia. A) west h a l f , and B) e a s t h a l f . Analyses of major and minor elements were undertaken by XRF and r e p o r t e d (Appendix 1A) as weight percent oxide; water and C0 2 e t c . were r e p o r t e d as l o s s on i g n i t i o n (LOI). Trace elements determined i n c l u d e : Ag, As, Ba, CI, Cr, Nb, N i , Rb, S, Sb, Se, Sr, Te, U, V, Y and Zr. Elemental data were r e p o r t e d i n ppm (Appendix 1A). D e t e c t i o n l i m i t s are 1 ppm. C o n t r o l samples c o n s i s t of t h r e e p a i r s of f i e l d d u p l i c a t e s and two UBC i n t e r n a l standards (Table 3.2). The f i e l d d u p l i c a t e samples were used t o determine the amount of combined sampling, p r e p a r a t i o n and a n a l y t i c a l e r r o r f o r each a n a l y s i s . The i n t e r n a l standard samples were used t o determine a n a l y t i c a l accuracy. 3.3.2. ERROR ANALYSIS Samples c o l l e c t e d as d u p l i c a t e s are evaluated, below, to determine the p r e c i s i o n of the geochemical a n a l y s e s . I n t e r n a l standard samples were used t o t e s t a n a l y t i c a l accuracy. The d u p l i c a t e analyses have e x c e l l e n t p r e c i s i o n . Combined r e l a t i v e e r r o r s f o r most elements are below 5%. E r r o r s f o r major, minor and t r a c e elements are 3%, 5%, and 10% r e s p e c t i v e l y . Thus, sampling v a r i a t i o n w i t h i n an outcrop does not seem t o be s i g n i f i c a n t l y l a r g e . P r e p a r a t i o n e r r o r a s s o c i a t e d with the analyses probably i n c l u d e s t r a c e Fe contamination from the jaw c r u s h e r and t r a c e Cr contamination from the tungsten c a r b i d e r i n g m i l l 30 TABLE 3.2: C o n t r o l samples analysed t o g e t h e r w i t h geochemical sample s u i t e , Wolf p r o s p e c t , Capoose Lake Area. SAMPLE MO. KA077A KA077B KA200A KA200B KA3-6A KA3-6B WP1 PI Dl D2 Dl D2 Dl D2 s S OXIDES Wt. % Si02 76.05 76.88 75.78 76.45 76.92 76.72 66.01 69.43 A1203 12.10 12.34 13.54 13.20 12.86 13.25 15.49 14.50 Ti02 0.20 0.20 0.24 0.23 0.16 0.-16 0.52 0.39 Fe203 1.73 1.73 2.55 2.46 1.19 1.18 4.63 4.29 MgO 0.01 0.00 0.35 0.38 0.02 0.00 1.67 1. 09 CaO 0.10 0.10 0.21 0.20 0.12 0.11 4.91 3.51 Na20 3.23 3.33 1.27 1.28 1.78 1.84 4.43 3.79 K20 4.81 4.87 4.26 4.08 6.23 6.29 1.64 2.21 MnO 0.02 0.02 0.06 0.06 0.00 0.00 0.09 0.08 P205 0.00 0.00 0.04 0.04 0.00 0. 00 0.14 0.08 ELEMENTS: ppm Ag 0 0 0 0 0 0 - -As 20 17 11 12 43 23 - -Ba 24 32 156 159 20 182 631 782 CI 0 0 0 0 0 11 - -Cr 5 8 0 0 9 51 60 41 Nb 23 24 21 21 23 11 5 4 Ni 3 0 2 6 0 0 46 4 Rb 196 199 235 232 295 203 8 13 S 69 69 94 97 117 83 60 121 Sb 1 1 1 3 4 4 - -Se 0 0 0 0 0 0 - -Sr 4 5 34 34 10 -15 752 229 Te 0 0 0 3 0 0 - -U 8 6 6 6 6 4 - -V 3 4 15 17 5 16 76 57 Y 79 80 83 81 58 46 18 23 Zr 592 587 500 501 340 379 124 115 1 (Hickson and J u r a s , 1986). A n a l y t i c a l e r r o r such as contamination and a n a l y t i c a l d r i f t cannot be determined because d u p l i c a t e samples were analysed s e q u e n t i a l l y . 3.3.3. ELIMINATION OF MOST ALTERED DATA A l t e r e d rocks from the Wolf p r o p e r t y were i d e n t i f i e d by p l o t t i n g major oxide data from Appendix 1A on diagrams m o n i t o r i n g metasomatism (Beswick, 1978). T h i s approach was necessary because d e u t e r i c and metamorphic processes can a f f e c t the a l k a l i e s , magnesium, c a l c i u m and p o s s i b l y the contents of o t h e r elements upon which chemical c l a s s i f i c a t i o n s depend. Logarithms of major oxide molecular p r o p o r t i o n s of a wide range of modern v o l c a n i c rocks d e f i n e d i s t i n c t t r e n d s on m o l e c u l a r p r o p o r t i o n r a t i o diagrams (Beswick, 1978). Si n c e these t r e n d s were d i s t i n g u i s h e d i r r e s p e c t i v e of the chemical c l a s s i f i c a t i o n of rocks from the a n a l y t i c a l data bank, they are i n s e n s i t i v e t o the d i f f e r e n c e s i n the d e t a i l e d f r a c t i o n a t i o n h i s t o r y of the rock s u i t e s (Beswick, 1978). Most samples from the Wolf p r o p e r t y p l o t w i t h i n the t i g h t l y d e f i n e d t r e n d s of modern v o l c a n i c rocks ( F i g 3.6). Samples, e s t a b l i s h e d as a l t e r e d , f o l l o w i n g the above ana l y s e s , were d e l e t e d from Appendix 1A and from chemical c l a s s i f i c a t i o n p l o t s i n s e c t i o n 3.3.4. Least a l t e r e d samples are i n Table 3.3. 32 o 1 log A l 2 0 3 / K 2 0 FIGURE 3.6: L o g a r i t h m i c oxide m o l e c u l a r p r o p o r t i o n r a t i o p l o t s ( K 2 0 denominator) f o r comparison of Wolf v o l c a n i c rocks to 'modern' v o l c a n i c s u i t e s and r e t r i e v a l of l e a s t a l t e r e d data (Beswick, 1978). Most dots .which r e p r e s e n t rocks from the Wolf p r o s p e c t (Appendix 1A) f a l l predominantly w i t h i n the l i m i t s f o r 'modern' v o l c a n i c s u i t e s . Least a l t e r e d rocks are i n Table 3.3. TABLE 3.3: Least a l t e r e d samples used f o r rock c l a s s i f i c a t i o n and chemical c l a s s i f i c a t i o n , Wolf prospect, Capoose Lake Area. SAMPLE NUMBER KA009 KA029 KA066 KA077 KA078 KA087 KA090 KA104 OXIDES (Wt. %) S i 0 2 77.89 78.57 A 1 2 0 3 11.01 11.65 T i 0 2 0.22 0.09 F6203 1 1.59 0.78 MgO 0.01 0.04 CaO 0.10 0.15 Na 20 2.95 2.25 K 20 4.45 5.32 MnO 0.01 0.01 P 2 0 5 0.02 0.01 LOI 0.79 0.67 t o t a l 99.04 99.54 74.21 76.05 76.46 14.41 12.10 12.14 0.36 0.20 0.21 0.96 1.73 1.83 '0.02 0.01 0.02 0.17 0.10 0.13 2.97 3.23 3.38 6.13 4.81 4.62 0.01 0.02 0.02 0.02 0.02 0.00 0.78 0.43 0.44 100.05 98.70 99.26 76.87 79.40 79.82 12.56 11.31 10.91 0.23 0.12 0.14 1.42 0.57 1.01 0.04 0.08 0.03 0.11 0.12 0.11 2.13 0.33 0.11 6.17 6.04 7.17 0.02 0.01 0.00 0.01 0.00 0.00 0.76 0.80 0.58 100.32 98.79 99.90 ELEMENTS (ppm) Nb 21 12 16 23 23 18 8 22 Y 65 22 59 79 83 72 18 40 Zr 65 69 456 592 600 564 84 313 CIPW NORM Q 41. 97 42. 91 31. 26 37. 03 36. 27 38. 62 53. 01 49. 93 C 1. 37 2. 19 2. 92 1. 58 1. 29 2. 47 4. 64 3. 17 Or 27. 36 32. 52 36. 88 29. 41 29. 54 37. 44 37. 83 44. 37 (Ab) 27. 57 20. 91 27. 16 30. 02 0. 66 19. 64 3. 14 1. 03 (An) 0. 38 0. 70 0. 73 0. 51 31. 36 0. 49 0. 63 0. 57 (En) 0. 00 0. 11 0. 06 0. 03 0. 06 0. 11 0. 23 1. 61 (Fs) 0. 00 0. 00 0. 00 3. 23 3. 38 0. 00 0. 00 0. 09 11 0. 00 0. 00 0. 02 0. 03 0. 03 0. 03 0. 00 0. 00 Hm 1. 15 0. 56 0. 68 1. 25 1. 31 1. 02 0. 42 0. 74 Ru 0. 16 0. 06 0. 25 0. 13 0. 13 0. 15 0. 09 0. 10 Ap 0. 04 0. 02 0. 04 0. 00 0. 00 0. 02 0. 00 0. 00 1. T o t a l i r o n i s expressed as F e 2 0 34 TABLE 3.3: (continued p2.) SAMPLE NUMBER KA106 KA112 KA133 KA135 KA141 KA163 KA178 KA184 OXIDES (Wt. %) S i 0 2 78. 11 80.45 73. 02 73.15 80.42 74.65 46.92 76.87 A 1 2 ° 3 12. 31 10.73 13. 23 14.05 10.62 14.77 14.88 11.79 T i 0 2 i 0. 18 0.15 0. 28 0.36 0.18 0.10 0.77 0.14 F e 2 0 3 i 1. 50 0.80 1. 75 1.87 1.81 1.41 10.97 1.31 MgO 0. 24 0.00 0. 14 0.08 0.06 0.13 8.51 0.07 CaO 0. 15 0.11 0. 18 0.19 0.12 0.15 •9.96 0.27 Na 20 0. 09 0.92 3. 44 3.60 0.14 1.48 1.79 3.36 K20 5. 39 6.00 5. 23 6.35 5.38 6.00 0.92 4.70 MnO 0. 04 0.00 0. 04 0.03 0.02 0.05 0.22 0.02 P 2 ° 5 0. 00 0.00 0. 04 0.09 0.02 0.00 0.32 0.02 LOI 1. 93 0.69 0. 63 0.34 1.19 1.16 3.22 0.52 t o t a l 99. 94 99.86 97. 98 100.11 99.97 99.91 98.49 99.07 ELEMENTS (ppm) Nb 18 21 14 13 17 22 0 16 Y 51 61 54 48 71 36 23 38 Zr 256 320 400 377 348 134 38 146 CIPW NORM Q 55. 46 50.21 31. 28 25.86 57.68 41.02 2.44 36.94 C 7. 03 2.88 1. 90 1.24 5.09 6.44 0.00 0.82 Or 33. 88 37.02 32. 09 37.89 33.70 36.76 5.78 28.61 (Ab) 0. 86 8.63 32. 08 32.65 1.33 13.78 18.12 31.08 (An) 0. 79 0.57 0. 66 0.36 0.49 0.43 33.44 1.25 (Wo) 0. 00 0.00 0. 00 0.00 0.00 0.00 6.99 0.00 (En) 0. 70 0.00 0. 40 0.00 0.18 0.37 6.99 0.00 Di 0. 00 0.00 0. 00 0.00 0.00 0.00 13.97 0.00 (En) 0. 00 0.00 0. 00 0.00 0.00 0.00 16.01 0.20 11 0. 07 0.00 0. 07 0.05 0.03 0.00 0.33 0.03 Hm 1. 11 0.58 1. 27 1.32 1.34 1.02 7.99 0.94 Ru 0. 10 0.11 0. 17 0.23 0.12 0.07 1.27 0.08 Ap 0. 00 0.00 0. 09 0.19 0.04 0.11 0.65 0.04 1. T o t a l i r o n i s expressed as F e 2 0 3 TABLE 3.3: (continued p3.) SAMPLE NUMBER KA195 KA221 KA3-6 KA4-9 OXIDES (wt. %) S i 0 2 48. 21 48. 21 77. 33 76. 92 A 1 2 0 3 11. 43 11. 43 12. 69 12. 86 T i 0 2 , 0. 66 0. 66 0. 10 0. 16 F e 2 ° 3 8. 27 8. 27 0. 66 1. 19 MgO 11. 97 11. 97 0. 04 0. 02 CaO 10. 24 10. 24 0. 17 0. 12 Na 20 1. 72 1. 72 0. 83 1. 78 K 20 0. 58 0. 58 7. 79 6. 23 MnO 0. 15 0. 15 0. 00 0. 00 P 2 ° 5 0. 18 0. 18 0. 01 0. 00 LOI 5. 76 5. 76 0. 57 0. 63 t o t a l 99. 15 99. 15 100. 20 99. 92 ELEMENTS (ppm) Nb 0 13 25 11 Y 32 24 56 58 Zr 54 87 339 379 CIPW NORM Q 2. 69 40. 41 40. 55 36. 21 C 0. 00 2. 94 3. 35 2. 97 Or 3. 64 47. 48 37. 97 37. 72 (Ab) 16. 42 7. 69 16. 49 21. 41 (An) 23. 13 0. 80 0. 61 0. 53 (Wo) 11. 13 0. 00 0. 00 0. 00 (En) 11. 13 0. 00 0. 00 0. 00 Di 22. 25 0, 00 0. 00 0. 00 (En) 24. 01 0. 11 0. 06 0. 08 11 0. 25 0. 00 Q-00 0. 00 Hm 6. 13 0. 47 0. 86 0. 79 Ru 1. 09 0. 07 0. 11 0. 25 Ap 0. 40 0. 02 0. 00 0. 04 1. T o t a l i r o n i s expressed as F e 2 0 3 36 3.3.4. CHEMICAL ROCK CLASSIFICATION Rocks on the Wolf p r o p e r t y were named c o n v e n t i o n a l l y i n s e c t i o n 3.2, u s i n g d e s c r i p t i v e f i e l d terms combined wi t h modal p e t r o g r a p h i c i n f o r m a t i o n (Table 3.1). Least a l t e r e d rocks are c l a s s i f i e d more f u l l y on the b a s i s o f major and t r a c e element geochemistry. Wolf v o l c a n i c rocks are dominantly hypersthene-corundum normative w i t h s i m i l a r normative compositions (Table 3.3). Wolf v o l c a n i c rocks are s u b a l k a l i n e ( F i g . 3.7; MacDonald, 1968; I r v i n e and Baragar, 1971). Major elements p l o t t e d on the AFM diagram of F i g u r e 3.8 demonstrates the c a l c a l k a l i n e a f f i n i t y . A c a l c a l k a l i n e t r e n d i s a l s o e v i d e n t i n F i g u r e 3.9, the Jensen p l o t (Jensen, 1976). T o t a l i r o n , a n alysed as F e 2 0 3 , was converted t o weight pe r c e n t FeO and F e 2 0 3 u s i n g the method of Sack e t a l . (1980). The c a l c u l a t i o n s were made a t 800°C and l n f 0 2 of 1 0 ~ 1 4 (from f i g u r e 6-12 i n Carmichael e t a l . , 1974). Rocks from the Wolf p r o p e r t y p l o t as o v e r s a t u r a t e d a c i d v o l c a n i c s dominantly w i t h i n the r h y o l i t e f i e l d on the TAS p l o t ( F i g . 3.10) a f t e r LeBas e t a l . (1986). Samples c l u s t e r as r h y o l i t e s on the Jensen p l o t and the " t r i a x i a l o x i d e" p l o t i n F i g u r e 3.11 (Church, 1975). Samples from the Wolf p r o p e r t y f a l l w e l l w i t h i n the r h y o l i t e f i e l d u s i n g immobile element p l o t s from Winchester and F l o y d ( F i g s . 3.12. and 3.13). S e l e c t e d minor and t r a c e elements such as T i , Zr, Y and Nb are r e l a t i v e l y immobile d u r i n g d e u t e r i c and metamorphic proc e s s e s . T h e r e f o r e FIGURE 3.7: Si02 wt % P l o t of a l k a l i e s v s . s i l i c a f o r an a l y s e s from the Wolf prospect (Table 3.3, boundaries are from MacDonald, 1968, and I r v i n e and Baragar, 1971). Assemblages are s u b - a l k a l i n e ( s e c t i o n 3.2.2), and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = p y r o c l a s t i c rocks, t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s . 38 FIGURE 3.8: AFM diagram w i t h analyses' from the Wolf p r o s p e c t (Table 3.3, boundaries are from Wager and Deer, 1939). Assemblages are c a l c - a l k a l i n e ( s e c t i o n 3.2.2), and are p l o t t e d u s i n g squares = mafic v o l c a n i c s , diamonds = p y r o c l a s t i c rocks, t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s . 39 FIGURE 3.9: Jensen C a t i o n p l o t f o r a n a l y s e s from the Wolf prospect (Table 3.3, boundaries are from Jensen, 1976). Assemblages are c a l c - a l k a l i n e t o t h o l e i i t i c ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g : squares = m a f i c v o l c a n i c s , diamonds = p y r o c l a s t i c r o c k s , t r i a n g l e s = r h y o l i t e flows, c i r c l e s = i n t r u s i o n s . 40 FIGURE 3.10: P l o t of a l k a l i e s v s . s i l i c a f o r a n a l y s e s from the Wolf pr o s p e c t (Table 3.3, boundaries are from Le Bas e t a l . 1986). Assemblages are predominantly r h y o l i t e s ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = p y r o c l a s t i c r o c k s , t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s . 41 o a O + o c» o Li. r o O CM 3 5 3 0 . n -2 5 2 0 1 0 -FIGURE 3.11 . 2 . 3 A I 2 0 3 / S 1 0 2 : T r i a x i a l oxide p l o t (FejOo, + FeO + 1/2 (MgO + CaO) vs. A^O^/SiO^) f o r analyses from the Wolf p r o s p e c t (Table 3.3) boundaries from Church, 1975). Assemblages are predominantly r h y o l i t e s ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = p y r o c l a s t i c r o cks, t r i a n g l e s = r h y o l i t e flows, c i r c l e s - i n t r u s i o n s . 42 84 80 76 72 68 64 CM o » 60 56 52 48 44 40 Rhyolite A A A Rhyodacite Dacite -f Comendite Pantel lerite Trachyte \ ^ Phonolite Trachyandesite \ Andesite Sub-Alkaline Basalt • • / \ / S Alkali-Basalt / / Basinite Nephelinite 0.01 0.10 1.00 Nb/Y wt % 10.00 FIGURE 3.12: S i 0 2 v s . Nb/Y p l o t f o r a n a l y s e s from the Wolf pr o s p e c t (Table 3.3, boundaries from Winchester and F l o y d , 1977). Assemblages are dominantly r h y o l i t e and rhyodaci,te ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = p y r o c l a s t i c r o c ks, t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s . 43 Sub-Alkaline Basalt 0.001 "t 0.01 0.10 1.00 10.00 Nb / Y FIGURE 3.13: Z r / T i 0 2 v s . Nb/Y p l o t f o r a n a l y s e s from the Wolf pr o s p e c t (Table 3.3, boundaries from Winchester and F l o y d , 1977). Assemblages are dominantly r h y o l i t e and r h y o d a c i t e ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = p y r o c l a s t i c rocks, t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s . diagrams m o n i t o r i n g these elements are r e l i a b l e chemical c l a s s i f i e r s . S ince S i 0 2 can be mobile d u r i n g a l t e r a t i o n , i t s use i n chemical c l a s s i f i c a t i o n p l o t s such as F i g u r e 3.12 can be l i m i t e d . Wolf data p l o t t e d on a Z r / T i 0 2 - Nb/Y diagram ( F i g . 3.13) shows t h a t the v o l c a n i c rocks from Wolf v a r y from a n d e s i t i c t o r h y o l i t i c i n composition. Most t e c t o n i c d e s c r i m i n a t i o n diagrams, d e f i n e d g e n e r a l l y f o r b a s a l t i c rocks, cannot be a p p l i e d t o f e l s i c v o l c a n i c rocks from the Wolf p r o p e r t y . However, the K 20 v s . S i 0 2 diagram o f G i l l (1981), m o d i f i e d t o i n c l u d e r h y o l i t e s (Spence, 1985), and the K 20 vs. Na 20 ( f o r 70% S i 0 2 ) diagram of Spence (1987) can be a p p l i e d t o Wolf f e l s i c v o l c a n i c r o c k s . Wolf v o l c a n i c s p l o t as high-K t o ve r y high-K ( F i g . 3.14), c a l c a l k a l i n e ( F i g . 3.8 and 3.9), and Fe-poor ( F i g . 3.8). T h i s r e l a t e s them t o a Type I I I a r c c l a s s i f i e d as " l e s s s o d i c " than Type I and I I a r c s (Spence, 1987). Type I I I a r c s are co n s i d e r e d t o be i n t r a c o n t i n e n t a l a r c s d e p o s i t e d on t h i c k c o n t i n e n t a l c r u s t , p o s s i b l y above subducted c o n t i n e n t a l c r u s t (Channel and Horvath, 1976). Whole rock and t r a c e element chemistry o f Ootsa Lake Group rocks has not been r e p o r t e d i n the l i t e r a t u r e . T h i s t h e s i s c h e m i c a l l y c l a s s i f i e s the r h y o l i t e member of the Ootsa Lake Group u s i n g v o l c a n i c rock samples from the Wolf p r o p e r t y . These samples are predominantly o v e r s a t u r a t e d f e l s i c v o l c a n i c rocks of c a l c a l k a l i n e a f f i n i t y . S i 0 2 v a l u e s are between 65 and 80%, consequently, a unimodal s u i t e i s i n d i c a t e d . 45 wt % K 2 0 12 40 46 50 55 60 65 70 75 80 wt % S I 0 2 FIGURE 3.14: K 20 v s . S i 0 2 p l o t f o r an a l y s e s from the Wolf p r o s p e c t (Table 3.3, boundaries are from de Rosen-Spence, 1976). A b b r e v i a t i o n s a re: LK = low potassium, MK = medium potassium, HK = h i g h potassium, VHK = very h i g h potassium, EHK = extremely h i g h potassium. F e l s i c v o l c a n i c assemblages have h i g h (HK) t o very h i g h (VHK) potassium ( s e c t i o n 3.2.2) and are p l o t t e d u s i n g diamonds = p y r o c l a s t i c r o cks, t r i a n g l e s = r h y o l i t e flows and c i r c l e s = i n t r u s i o n s . Wolf Ootsa Lake Group r h y o l i t e s c o n t r a s t w i t h Kasalka Group and Hazelton Group v o l c a n i c r o c k s . The l a t t e r two are Type I I a r c s (Spence, 1987), which are d i s t i n c t l y bimodal i n c h a r a c t e r . However, Wolf v o l c a n i c s , c l a s s i f i e d as Type I I I a r c s by Spence (1987), compare with South Fork v o l c a n i c r o c k s , Yukon T e r r i t o r y (Wood and Armstrong, 1982) which are a s u b a e r i a l i n t r a c o n t i n e n t a l a r c sequence composed of c a l c a l k a l i n e , p o t a s s i c and Fe-poor d i f f e r e n t i a t e d flows and t u f f s . 3.3.5. PETROGENESIS Wolf v o l c a n i c rocks may have o r i g i n a t e d from one or more igneous p r o c e s s e s . Pearce element r a t i o diagrams (Pearce, 1968) are used below t o r e c o g n i s e c o g e n e t i c rock a n a l y s e s and t o e v a l u a t e a hypothesis of f e l d s p a r c r y s t a l f r a c t i o n a t i o n . True r e l a t i o n s h i p s among v a r i a b l e s are shown by d i v i d i n g the v a r i a b l e s by a parameter t h a t remains constant throughout the v a r i a t i o n (Pearce, 1968). Chemical data r e p o r t e d i n weight percent (wt.%) or p a r t s per m i l l i o n (ppm) are i n t e n s i v e v a r i a b l e s (independent of the t o t a l q u a n t i t y of matter i n the system under c o n s i d e r a t i o n ) . In o r d e r t o examine e x t e n s i v e chemical v a r i a t i o n (dependent on the t o t a l amount of matter i n the system under c o n s i d e r a t i o n ) , oxides and elements are converted t o moles and r a t i o e d u s i n g a common d i v i s o r , which i s assumed t o remain constant throughout the v a r i a t i o n . V a r i a t i o n s between Pearce element r a t i o s can be d i r e c t l y r e l a t e d t o min e r a l formulae. Thus Pearce v a r i a t i o n diagrams i l l u s t r a t e the s p a t i a l , m i n e r a l o g i c and chemical v a r i a t i o n i n rock s u i t e s , and are used t o e v a l u a t e processes i n v o l v e d i n t h e i r f o rmation. Pearce element r a t i o s of incompatible t r a c e data are used t o t e s t whether rocks from the Eocene v o l c a n i c s u i t e a t Wolf (Table 3.3) are c o g e n e t i c . Pearce p l o t s were generated u s i n g PEARCE.PLOT a t u r b o - p a s c a l program (Stanley and R u s s e l l , 1988). P l o t s o f Zr/Nb v s . Y/Nb as w e l l as Y/Nb vs. Ti/Nb show t h a t the v a r i a n c e i n the conserved element r a t i o s f o r the data i s l e s s than the v a r i a n c e a t t r i b u t a b l e t o a n a l y t i c a l u n c e r t a i n t y ( F i g s . 3.15 and 3.16). Thus, the Ootsa Lake Group v o l c a n i c s u i t e a t Wolf c o u l d r e p r e s e n t a s i n g l e magma s e r i e s . J u r a s s i c H azelton Group rocks c l u s t e r s e p a r a t e l y from the Ootsa Lake Group v o l c a n i c s u i t e ( F i g s . 3.15 and 3.16). These a n d e s i t e s are u n r e l a t e d t o the Ootsa Lake Group v o l c a n i c s e r i e s a t Wolf. The observed chemical d i v e r s i t y o f the Wolf v o l c a n i c s u i t e c o u l d be the r e s u l t o f f e l d s p a r d i f f e r e n t i a t i o n s i n c e the Ootsa Lake Group flows and t u f f s can be d e r i v e d from a s i n g l e magma. The a f f e c t s o f f e l d s p a r f r a c t i o n a t i o n are modelled on a Pearce element r a t i o diagram w i t h the axes Y = 2Ca + Na + K / i and X = A l / i , where i = a conserved element. T h i s f i g u r e examines f e l d s p a r d i f f e r e n t i a t i o n alone; rock compositions t h a t are r e l a t e d through accumulation o r l o s s of p l a g i o c l a s e or potassium f e l d s p a r d e f i n e a t r e n d w i t h a sl o p e o f one on t h i s diagram. 68.00 53.00 38.00 N 23.00 8.00 -7.00 4 -7.00 1.00 St. Dev. Error Bounds •w N-25 2.80 12.60 22.40 Y / Nb 32.20 42.00 FIGURE 3.15: Zr/Nb vs. Y/Nb p l o t f o r analyses from the Wolf prospect (Table 3.3) shows t h a t the Eocene v o l c a n i c s u i t e i s cogenetic because the v a r i a n c e i n conserved element r a t i o s f o r the data i s l e s s than the v a r i a n c e a t t r i b u t a b l e t o a n a l y t i c a l u n c e r t a i n t y . CO 42.00 32.20 1.00 St. Dev. Error Bounds 22.40 z 12.60 2.80 • -7.00 0.30 N = 25 0.00 0.30 0.60 Tl / Nb 0.90 1.20 FIGURE 3.16: Y/Nb vs. Ti/Nb p l o t f o r analyses from the Wolf prospect (Table 3.3) shows t h a t the Eocene v o l c a n i c s u i t e i s cogenetic because the v a r i a n c e i n conserved element r a t i o s f o r the data i s l e s s than the v a r i a n c e a t t r i b u t a b l e t o a n a l y t i c a l u n c e r t a i n t y . The element T i i s used as a conserved element because i t i s probably not i n v o l v e d i n c r y s t a l l i z a t i o n of r h y o l i t e s a t Wolf ( F i g . 3.16). Data from wolf p l o t t e d on the Pearce p l o t f o r f e l d s p a r d i f f e r e n t i a t i o n d e f i n e s a t r e n d of s l o p e 1.00 w i t h s t r o n g c o r r e l a t i o n of r 2 = 0.89; N = 23 ( F i g . 3.17). Thus, the hypothesis of f e l d s p a r d i f f e r e n t i a t i o n cannot be r e j e c t e d , and the chemical v a r i a b i l i t y o f Wolf v o l c a n i c rocks i s probably the r e s u l t of accumulation and l o s s of p l a g i o c l a s e and potassium f e l d s p a r . 3.4 DATING 3.4.1 K-AR Three samples from the Wolf p r o p e r t y were dated by whole rock K-Ar (Table 3.4). They c o n s i s t e d o f : (1) a c r y s t a l t u f f (KA135: Eo 6) which marks the top of the p y r o c l a s i t i c package at Wolf, (2) a s p h e r u l i t i c and flow banded r h y o l i t e flow (KA112: Eo 7) , and (3) a c o a r s e - g r a i n e d r h y o l i t e porphyry (KA078: E o g ) . The purpose of the d a t i n g was t o o b t a i n an age f o r the v o l c a n i c and i n t r u s i v e rocks a t Wolf t o c o n f i r m t h a t they are Ootsa Lake Group r o c k s . The K analyses were by atomic a b s o r p t i o n (by K.R. S c o t t ) , and the Ar analyses were by i s o t o p e d i l u t i o n u s i n g c o n v e n t i o n a l procedures (by J . H a r a k a l ) . The decay c o n s t a n t s used are \ f + Xe»= 0.581 * 1 0 ~ 1 0 y e a r - 1 ; 4.962 * 1 0 " 1 0 y e a r ' 1 ; and 4 0K/K = 1.167 * 10" 2 atomic p e r c e n t ( S t e i g e r and Jager, 1977). - 1 0 . 0 0 5 0 . 0 0 1 10.00 1 7 0 . 0 0 2 3 0 . 0 0 2 9 0 . 0 0 Al / Tl FIGURE 3.17: 2Ca+Na+K/Ti vs. A l / T i p l o t o f data from the Wolf property (Table 3.3) t o t e s t the h y p o t h e s i s of f e l d s p a r f r a c t i o n a t i o n . 52 TABLE 3.4: K-Ar ages f o r Ootsa Lake Group v o l c a n i c rocks from the Wolf prospect, c e n t r a l B r i t i s h Columbia. Samples are l o c a t e d on F i g u r e 3.5. SAMPLE NUMBER LATITUDE/ 40 Ar LONGITUDE (wt.%) (moles/g) (%f * i o " 1 0 4 0 A r , ad DATE 1 AGE 2 (Ma) KA 078 53°11 /15" r h y o l i t e 125°29 /30" porphyry whole rock 4.22 3.530 67.4 47.6+1.7 Middle Eocene KA 112 53°12 /10" r h y o l i t e 125°28 /10" whole rock 5.35 4.538 89.5 48.3+1.7 Middle Eocene KA 135 c r y s t a l t u f f whole rock 53°ll /50" 125°27 /15" 5.38 4.722 75.7 49.9+1.7 Middle Eocene Analyses were c a r r i e d out a t The U n i v e r s i t y o f B r i t i s h Columbia, Department o f G e o l o g i c a l S c i e n c e s , by K.R. S c o t t (K) and J . Harakal ( A r ) . Age i s based on date and time s c a l e o f the DNAG 1983 Time S c a l e (Palmer, 1983). A l l t h r e e whole rock K-Ar dates c o n f i r m a mid-Eocene (L u t e t i a n ) age (46 t o 50 Ma) f o r v o l c a n i c rocks a t the Wolf p r o p e r t y . T h i s date i s w i t h i n the age l i m i t s a s s i g n e d t o Ootsa Lake Group v o l c a n i c rocks by T i p p e r (1963). The c e s s a t i o n of p y r o c l a s t i c v o l c a n i s m and commencement of r h y o l i t e doming i s bracketed by the ages of E o 6 and E o 7 (49.9 + 1.7 t o 48.3 + 1.7 Ma). I n t r u s i o n of E o g ( r h y o l i t e porphyry) i n t o the v o l c a n i c s u c c e s s i o n ( F i g . 3.1) took p l a c e a t the same time or up t o a m i l l i o n years l a t e r a t 47.6 + 1.7 Ma. The Capoose b a t h o l i t h , a quartz monzonite i n t r u s i v e 7 km n o r t h of the p r o p e r t y has been dated as Late Cretaceous (67 Ma) by the K-Ar technique u s i n g b i o t i t e ( s e c t i o n 4.4). Such evidence p r e c l u d e s a g e n e t i c r e l a t i o n s h i p between the i n t r u s i v e a t Capoose and volcanism a t Wolf. 3.4.2 PALYNOLOGY E p i c l a s t i c rocks on the Wolf p r o p e r t y do not outcrop ( F i g . 3.1) but were i n t e r s e c t e d i n d r i l l c o r e . These p o o r l y c o n s o l i d a t e d s i l t s t o n e s , sandstones, and t u f f s are a t l e a s t 30 metres t h i c k ( F i g . 3.2). Four samples were s y s t e m a t i c a l l y c o l l e c t e d from the s i l t s t o n e s f o r a study of f o s s i l spores and p o l l e n . The study was undertaken t o determine the r e l a t i v e age of the e p i c l a s t i c u n i t w i t h r e s p e c t t o o v e r l y i n g Ootsa Lake Group v o l c a n i c r o c k s . Samples were crushed with a s t e e l mortar and d i s s o l v e d i n s t r o n g h y d r o f l u o r i c a c i d o v e r n i g h t . Remaining carbonate and o r g a n i c d e b r i s was s i e v e d t o minus 10 and p l u s 2 0 mesh. Strong h y d r o c h l o r i c a c i d was used t o d i s s o l v e carbonates and t e s t f o r p y r i t e — m o s t s o l u t i o n s turned green which i s d i a g n o s t i c o f the presence of i r o n . Palynomorphs were i s o l a t e d by immersing samples i n z i n c bromide which induces m i n e r a l s t o s e t t l e and o r g a n i c d e b r i s t o f l o a t . Samples of the separated o r g a n i c d e b r i s were p i p e t t e d i n t o d i f f e r e n t c o n t a i n e r s and r i n s e d with s t r o n g n i t r i c a c i d f o l l o w e d by water. Samples were then p l a c e d i n s o l u t i o n f o r e i g h t hours t o make the palynomorphs l e s s opaque. S a f r a n i n was used t o s t a i n the samples i n p r e p a r a t i o n f o r p e t r o g r a p h i c o b s e r v a t i o n . A s m a l l but w e l l - p r e s e r v e d assemblage o f palynomorphs (Table 3.5) were i d e n t i f i e d by G.E. Rouse a t The U n i v e r s i t y of B r i t i s h Columbia. The e p i c l a s t i c rocks a t Wolf c o r r e l a t e c l o s e l y w i t h assemblages from the F r a s e r Bend Formation along the F r a s e r R i v e r , and e q u i v a l e n t s along and f l a n k i n g Nechako R i v e r which are Middle Miocene. T h i s age i s estimated t o be 17-13.5 Ma, or B a r s t o v i a n on the mammalian s c a l e (Rouse and Mathews, 1979; Mathews and Rouse, 1984). The c l i m a t e i s estimated t o have been warm temperate, wi t h an annual p r e c i p i t a t i o n between 1000 and 1300 mm and mean annual temperature o f about 12-16°C (Rouse, p e r s . comm. 1988). The e p i c l a s t i c rocks were s u b j e c t e d t o p a l e o -temperatures near 200°C as i n d i c a t e d by the r e q u i r e d l e n g t h of time (at l e a s t 8 hours) needed t o b l e a c h palynomorphs i n S c h u l t z ' s s o l u t i o n (Rouse, p e r s . comm., 1988). TABLE 3.5: Palynomorphs i n Fraser-Bend e q u i v a l e n t mid-Miocene e p i c l a s t i c rocks a t the Wolf prospect, c e n t r a l B r i t i s h Columbia (G. E. Rouse, pe r s . comm. 1988). FERN SPORES: L a e v i g a t o s p o r i t e s ovatus P o l y p o d i i s p o r i t e s favus D e l t o i d o s p o r a diaphana Polypodiaceae spore c f . D r y o p t e r i s a u s t r i a c a (spreading wood fern) CONIFER POLLEN: Pinus c f . c o n t o r t a P. ha p l o x y l o n - type P. d i p l o x y l o n - type Tsuga h e t e r o p h y l l i t e s T. mertensiana Pseudotsuga c f . m e n z i e s i i Abies sp. T a x o d i a c e a e p o l l e n i t e s h i a t u s ANGIOSPERM POLLEN: Pter o c a r y a s t e l l a t a F r a x i n o i p o l l e n i t e s v a r i a b i l i s F. medius Alnus v e r a c f . Quercus s h i a b e n s i s Q u e r c o i d i t e s m i c r o h e n r i c i C o r y l u s / C a r p i n u s 56 3.5 MINERALIZATION AND ALTERATION The Wolf epithermal prospect i s c h a r a c t e r i z e d by low-s u l p h i d e zones i n quartz v e i n s and b r e c c i a s c o n t a i n i n g electrum, n a t i v e s i l v e r , s i l v e r s u l p h i d e s and s u l p h o s a l t s . W a l l r o c k a l t e r a t i o n i s t y p i c a l l y a r g i l l i c o r s e r i c i t i c b o r d e r i n g the s i l i c i f i e d zones near v e i n s . A l s o near the v e i n s are disseminated f i n e - g r a i n e d potassium f e l d s p a r or c h l o r i t e . M i n e r a l and a l t e r a t i o n assemblages resemble those of a d u l a r i a - s e r i c i t e epithermal systems d e s c r i b e d by Hayba e t a l . (1985). F i v e d i s t i n c t m i n e r a l i z e d zones have been d e l i n e a t e d on the p r o p e r t y : (1) the Chopper Pad zone, (2) the Lookout zone, (3) the Ridge zone, (4) the Pond zone, and (5) the E a s t zone ( F i g . 3.18). The main d e p o s i t area comprises the Ridge and Pond zones i n the c e n t r a l p a r t of the p r o p e r t y . A t r e n c h i n the Ridge zone r e t u r n e d 8.49 g/tonne g o l d and 42.41 g/tonne s i l v e r over 7.5 m (Holmgren and Cann, 1984). Surf a c e samples from the Pond zone are t y p i f i e d by g o l d v a l u e s g r e a t e r than 0.5 g/tonne; the h i g h e s t g o l d and s i l v e r v a l u e s obtained were 1.4 g/tonne and 19 g/tonne r e s p e c t i v e l y (Holmgren and Cann, 1984). D e t a i l e d d e s c r i p t i o n of the nature and occurrence of m i n e r a l i z e d zones wi t h d i s t r i b u t i o n o f ore m i n e r a l s and s t a t i s t i c a l a nalyses of metals f o l l o w . 3.5.1 DESCRIPTION OF ZONES Surfa c e samples from a l l f i v e zones were examined i n d e t a i l i n 1985. Gold and s i l v e r m i n e r a l i z a t i o n i s 57 W E S T H A L F FIGURE 3.18: M i n e r a l i z e d zones of the Wolf p r o s p e c t , Capoose Lake area, c e n t r a l B r i t i s h Columbia. A)west h a l f , and B) east h a l f . 58 EAST HALF FIGURE 3.18: M i n e r a l i z e d zones of the Wolf p r o s p e c t , Capoose Lake area, c e n t r a l B r i t i s h Columbia. A)west h a l f , and B) e a s t h a l f . a s s o c i a t e d w i t h v e i n and b r e c c i a t e x t u r e s i n a l l zones. I n d i v i d u a l v e i n s a t Wolf have c h a r a c t e r i s t i c f e a t u r e s of h i g h - l e v e l emplacement such as c h a l c e d o n i c q u a r t z , b r e c c i a t e d w a l l r o c k fragments cemented by chalcedony, c o l l o f o r m l a y e r i n g , cockscomb growth of well-formed q u a r t z , and drusy c a v i t i e s . R e l a t i v e t i m i n g of hydrothermal events on the p r o p e r t y ( s e c t i o n 3.5.2) was estimated from c r o s s - c u t t i n g r e l a t i o n s h i p s b e s t d i s p l a y e d i n trenches on the Ridge Zone ( F i g . 3.19). Block f a u l t i n g preceeded formation of v e i n s and b r e c c i a s on the p r o p e r t y and p r o v i d e d c o n d u i t s f o r hydrothermal f l u i d s a t Wolf ( s e c t i o n 3.2.3). The extent and nature of the Ridge and Pond zones with depth i s d i s p l a y e d i n the v e r t i c a l c r o s s - s e c t i o n s of F i g u r e s 3.2 0 and 3.21 c o n s t r u c t e d from logged core and the a i d of the GEOLOG system (name r e g i s t e r e d by I n t e r n a t i o n a l Geosystems C o r p o r a t i o n , Vancouver, B.C.). The Chopper Pad zone, i n the northwestern p a r t of the p r o p e r t y ( F i g 3.18A), i s an i r r e g u l a r north-south t r e n d i n g zone up t o 500 m long. I t i s c h a r a c t e r i z e d by p e r v a s i v e s i l i c i f i c a t i o n o f massive and b r e c c i a t e d r h y o l i t e ( u n i t 8, F i g 3.1). S i l i c i f i c a t i o n i s mainly i n f r a c t u r e s f i l l e d w ith grey-white chalcedony or i n b r e c c i a s cemented by t r a n s l u c e n t quartz ( P l a t e 3.7). However, massive replacement of r h y o l i t e by s i l i c a occurs as pods up t o 2 m a c r o s s . A bladed quartz-carbonate t e x t u r e i s o f t e n developed w i t h i n these pods ( P l a t e 3.8). T h i s t e x t u r e , d e s c r i b e d as l a m e l l a r b r e c c i a 2mm q u a r t z v e i n l e t s banded c h a l c e d o n y q u a r t 2 - K - f e l d s p a r / ^ f r a g m e n t s c r o s s c u t by d r u s y q u a r t z v e i n l e t s flow-banded r h y o l i t e w i t h m i c r o v e i n l e t s 1 cm b l a d e d q u a r t z c a r b o n a t e v e i n s v o l c a n i c b r e c c i a fragments up to, _ , IA Trench 6 l u cm flow-banded r h y o l i t e w i t h b l a d e d q u a r t z -c a r b o n a t e ^ 5 mm q u a r t z v e i n l e t s d r u s y q u a r t z f r a c t u r e f i l l i n g s Trench A b r e c c i a t e d q u a r t 2 p o r p h y r y , fragments up t o 10 cm, stockwork b l a d e d q u a r t z - c a r b o n a t e , ^ d r u s y q u a r t 2 v e i n s , c o c k a d e - t e x t u r e d v e i n l e t s Trench 7 c h a l c e d o n i c and cockade t e x t u r e d v e i n l e t s ^ 1 cm t h i c k , minor b l a d e d q u a r t z - c a r b o n a t e v o l c a n i c b r e c c i a w i t h b l a c k and g r e e n f i n e - g r a i n e d m a t r i x Trench 5 r h y o l i t e 5 mm to 2 cm q u a r t z v e i n l e t s , minor b l a d e d q u a r t z -c a r b o n a t e 1 cm d r u s y q u a r t z v e i n l e t s , v o l c a n i c b r e c c i a Trench 6 b l a d e d q u a r t z -c a r b o n a t e 1 cm c h a l c e d o n i c v e i n l e t s v o l c a n i c b r e c c i a i n f i l l e d by , m i c r o c r y s t a l l i n e q u a r t z b l a d e d q u a r t z - c a r b o n a t e p a t c h e s b l a d e d q u a r t z - c a r b o n a t e v o l c a n i c b r e c c i a b l a d e d q u a r t z % q u a r t z p o r p h y r y Trench q u a r t z p o r p h y r y ^ w i t h stockwork b l a d e d . q u a r t z - c a r b o n a t e , cockade q u a r t z v e i n l e t s and d r u s y q u a r t z c a v i t i e s q u a r t z ^ / p o r p h y r y L e c t H D • 0*11* 0 t « * 0 Trench 1-8 Trench 9- II Ptl, fltob »0«r>t>le numbit Trinch chip sample number I9B4 trenching 1983 trenching N T S 9 3 F / 3 S C A L E FIGURE 3.19: Trench map of the Ridge Zone ( F i g u r e 3.18) showing d i s t r i b u t i o n of v e i n and b r e c c i a types from the Wolf prospect, c e n t r a l B r i t i s h Columbia. Gold and s i l v e r grades are i n F i g u r e 3.24. 1 3 0 0 -Metres above sea level 1 2 5 0 -DDH006 DDH004 DDH003 DDH005 £D"°°i DDH001 Metres 2 0 4 0 6 0 8 0 1 0 0 LEGEND , SIITSTONE, MS TUFFACEOUS SANDSTONE E04 CONGLOMERATE EOS EOe VOLCANIC BRECCIA ASH TUFF RHYOLITE FLOWS E09 RHYLITE PORPHYRY E02 I FELSIC LAPILLI T U F F | E06 | C R Y S T A L T U F F LITHIC,CRYSTAL TUFF| EO7 | EO10 QUARTZ PORPHYRY EOs RHYOLITE Jha ANDESITE FLOWS, FLOW BRECCIA SYMBOLS : geological contact; known,assumed \Av\m M M M fault;known, assumed j^ v—f foliation 3 ^ , lineation vein, wi th dip FIGURE 3.20: North-south v e r t i c a l s e c t i o n (C-C':Fig. 3.1A) of the Wolf prospect from s u r f a c e mapping and core l o g g i n g of the Ridge and Pond zones, Wolf p r o s p e c t , c e n t r a l B r i t i s h Columbia. en 62 w 1300 Metres a bo ve sea level 12 50 120 0 • 1150 E 0 6 M« E 0 7 00H2 D0H3 E 0 7 M< Metres 40 S C A L E SO LEGEND ~7~| SILTSTONE, MS TUFFACEOUS 1 SANDSTONE E04 A S H T U F F EOi C O N G L O M E R A T E E05 EOe VOLCANIC BRECCIA R H Y O L I T E F L O W S E O 9 R H Y O L I T E P O R P H Y R Y E 0 2 F E L S I C LAP ILL I T U F F E 0 6 C R Y S T A L T U F F EO 10 EO3 L ITH IC , C R Y S T A L TUFFJ E O 7 [ R H Y O L I T E Jha Q U A R T Z P O R P H Y R Y A N D E S I T E F L O W S , F L O W B R E C C I A SYMBOLS 2D — — geological contact; known,assumed M M fault;known, assumed foliation -^-l ineation • i * vein, with dip • diamond drill hole(DDH) •»> DDH trace FIGURE 3.21: East-west v e r t i c a l s e c t i o n (D-D':Fig..3.1A) of the Wolf pr o s p e c t from s u r f a c e mapping and core l o g g i n g of the Ridge and Pond zones system, Wolf p r o s p e c t , c e n t r a l B r i t i s h Columbia. PLATE 3.7: M o n o l i t h i c quartz-cemented v o l c a n i c b r e c c i a from t h e Ridge zone. Sample KATR7-3, Wolf p r o s p e c t . PLATE 3.8: B l a d e d c a r b o n a t e i n q u a r t z from t h e R i d g e zone. Sample KATR9-1, Wolf p r o s p e c t . ore by L i n g r e n (1933), i s c h a r a c t e r i s t i c of many e p i t h e r m a l d e p o s i t s ( c f . McDonald, 1987) and may r e f l e c t quenching due to b o i l i n g and r a p i d c o o l i n g . The Lookout, Ridge and Pond zones, s e p a r a t e d by l e s s than 200 m on a h i l l i n the c e n t r a l p a r t o f the p r o p e r t y , are t e x t u r a l l y s i m i l a r . S p e c i f i c a l l y , b laded q u a r t z carbonate patches from 10 cm to 0.5 m i n s i z e ( P l a t e 3.8) commonly occur with d i f f u s e boundaries i n each zone. The nature of t h i s quartz carbonate t e x t u r e , which c o n t a i n s the h i g h e s t g o l d and s i l v e r v a l u e s on the p r o p e r t y (Holmgren and Cann, 1985) i s d i s c u s s e d i n s e c t i o n 3.5.2. The Lookout zone i s t y p i f i e d by m i l k y white v e i n s up t o 2 m wide ( P l a t e 3.9). These v e i n s have sharp c o n t a c t s w i t h u n a l t e r e d host c r y s t a l t u f f (Eo 6, F i g 3.1). L o c a l l y , i r r e g u l a r patches, up t o 2 0 cm i n diameter, of bla d e d quartz carbonate v e i n i n g occur w i t h i n broad d i f f u s e pods of white v e i n q u a r t z . The Ridge zone i s t y p i c a l l y i n h e t e r o l i t h i c b r e c c i a s w i t h i n a flow-banded r h y o l i t e ( Eo 7, F i g 3.1). The h e t e r o l i t h i c fragments comprise grey, green o r white, a p h a n i t i c t o p o r p h y r i t i c v o l c a n i c fragments from 1 cm t o 4 cm i n diameter ( P l a t e 3.4). Some of the fragments are c l a y -a l t e r e d . Fragments a l s o i n c l u d e broken c h i p s o f banded t a n -white chalcedony or quartz. H e t e r o l i t h i c fragments are rimmed by white chalcedony and cemented by t r a n s l u c e n t q u a r t z . The b r e c c i a s are c r o s s c u t by l a t e stage quartz v e i n l e t s ( P l a t e 3.10). Minor quartz-carbonate patches up to 6 5 PLATE 3.9: M i l k y w h i t e q u a r t z v e i n s as t h i c k as 2 m a t t h e Lookout Zone, Wolf p r o s p e c t . PLATE 3.10: Drusy v e i n q u a r t z from t h e E a s t zone. Sample KA188, Wolf p r o s p e c t . 0.5 m occur w i t h i n l a r g e r white v e i n s . These v e i n s are p e r i p h e r a l t o b r e c c i a areas. The presence of fragments from p r e v i o u s hydrothermal events, rimming of fragments, p e r i p h e r a l v e i n i n g , and l a t e stage v e i n l e t s d e f i n e a m u l t i s t a g e h i s t o r y of m i n e r a l i z a t i o n . The Pond zone i s t y p i f i e d by m i l k y white s u c r o s i c q u a r t z , c r y p t o c r y s t a l l i n e grey-white banded c h a l c e d o n i c v e i n s ( P l a t e 3.11) and v e i n l e t s hosted i n r h y o l i t e porphyry ( E o g : F i g 3.1). L o c a l l y v e i n l e t s are vuggy and c o n t a i n pods o f bladed q u a r t z . The E a s t zone, on a r i s e on the East s i d e of the p r o p e r t y ( F i g . 3.18B), i s separated from the o t h e r zones by about 1 km. Textures are t y p i f i e d mainly by l a t e stage drusy quartz c r y s t a l s up t o 2 cm long i n vugs. The vugs are o f t e n c r o s s c u t by 2 mm quartz v e i n l e t s . D i s t r i b u t i o n of chalcedony and drusy quartz and bladed quartz-carbonate v e i n t e x t u r e s w i t h depth from the Ridge and Pond zones are i l l u s t r a t e d on v e r t i c a l s e c t i o n s ( F i g s . 3.22 and 3.23). Each s e c t i o n i s hand contoured t o d e f i n e the f o l l o w i n g amounts of v e i n type: (1) l e s s than 0.1%, (2) between 0.1 and 1%, (3) between 1 and 5%, and (4) g r e a t e r than 5%. The Ridge zone i s c h a r a c t e r i z e d on s u r f a c e by m u l t i s t a g e b r e c c i a t i o n and v e i n i n g events ( F i g . 3.19). Highest g o l d grades are a s s o c i a t e d w i t h v e i n s c o n t a i n i n g abundant bladed quartz-carbonate ( F i g 3.24). At depth, however, the markedly drusy quartz v e i n s are t r u n c a t e d by a north-south, westwardly d i p p i n g t h r u s t f a u l t ( F i g . 3.23A). 6 7 PLATE 3.12: Photomicrograph of c l e a r c r y s t a l l i n e quartz i n t e r s t i t i a l to dark bladed carbonate, Ridge zone. Sample K A T R 9 - 1 , Wolf prospect. FIGURE 3.22: North-south v e r t i c a l s e c t i o n (C-C':Fig. 3.1A) of the Wolf prospect showing d i s t r i b u t i o n o f v e i n and b r e c c i a phases with depth ( r e f e r t o F i g u r e 3.20 f o r geology). CO FIGURE 3.22: North-south v e r t i c a l s e c t i o n ( C - C : F i g . 3. 1A) of the Wolf prospect showing d i s t r i b u t i o n o f v e i n and b r e c c i a phases w i t h depth ( r e f e r t o F i g u r e 3.20 f o r g e o l o g y ) . FIGURE 3.22: North-south v e r t i c a l s e c t i o n ( C - C : F i g . 3.1A) of the Wolf prospect showing d i s t r i b u t i o n of v e i n and b r e c c i a phases wi t h depth ( r e f e r t o F i g u r e 3.20 f o r g e o l o g y ) . o FIGURE 3.23: East-west v e r t i c a l s e c t i o n (D-D':Fig. 3.1A) of the Wolf prdspect showing d i s t r i b u t i o n o f v e i n and b r e c c i a phases w i t h depth ( r e f e r t o F i g u r e 3.23 f o r g e o l o g y ) . FIGURE 3.23: East-west v e r t i c a l s e c t i o n (D-D':Fig. 3.1A) of the Wolf prdspect showing d i s t r i b u t i o n of v e i n and b r e c c i a phases with depth ( r e f e r t o F i g u r e 3.23 f o r geology). to FIGURE 3.23: East-west v e r t i c a l s e c t i o n (D-D':Fig. 3.1A) of the Wolf prdspect showing d i s t r i b u t i o n o f v e i n and b r e c c i a phases with depth ( r e f e r t o F i g u r e 3.23 f o r geology). * i I, 010 • 0 0 / 1 ». ' ' »• ' o or 0 07 • o or « O-OT if -Q-J, 0 14 • 0 If o 1140 ,1710 0 L E C END * J-F.O JO Pit , Ag g/t, Au g/i Trinch I - d 1964, Agg/r, Aug/t Tfflncn 9- II I 9 85, Ag ppm , Aug/t N T S 9 3 F / 3 S C A L E 13 Maria* FIGURE 3.24: Trench map of the Ridge Zone ( F i g s . 3.18 showing d i s t r i b u t i o n of g o l d and s i l v e r grades, Wolf prospect (from Holmgren and Cann, 1985). R e f e r t o F i g u r e 3.19 f o r d i s t r i b u t i o n of v e i n and b r e c c i a t e x t u r e s . Drusy, c h a l c e d o n i c quartz and bladed quartz-carbonate v e i n s abundant a t the Pond zone ( F i g s . 3.22 and 3.23). The v e i n s extend t o depths of a t l e a s t 100 m from the s u r f a c e . A q u a l i t i t i v e a l t e r a t i o n map ( F i g . 3.25) shows the extent of a r g i l l i c a l t e r a t i o n a c r o s s the p r o p e r t y . Zones of h i g h or i n t e n s e c l a y a l t e r a t i o n g e n e r a l l y correspond w i t h the m i n e r a l i z e d zones o u t l i n e d i n s e c t i o n 3.5.1. 3.5.2 CHARACTER OF VEINS AND BRECCIAS E i g h t t e m p o r a l l y and t e x t u r a l l y d i s t i n c t phases of v e i n and b r e c c i a d e p o s i t i o n are r e c o g n i s e d a t Wolf. These phases are b e s t d i s p l a y e d i n trenches on the Ridge zone ( F i g . 3.19). The r e l a t i v e t i m i n g of these hydrothermal events, m o d i f i e d from Cann (1984), i s l i s t e d i n Table 3.6. I n i t i a t i o n of hydrothermal events a t Wolf i s marked by replacement of r h y o l i t e fragments up t o 1 cm i n diameter i n the r h y o l i t e (Eo 7) w i t h b l a c k chalcedony. P e r v a s i v e s i l i c i f i c a t i o n o f r h y o l i t e accompanied the replacement of these fragments. B r e c c i a t i o n of the r h y o l i t e (Eo 7) f o l l o w e d , perhaps as a r e s u l t of r esurgent doming of E o 7 . The newly opened c a v i t i e s allowed growth of c o a r s e - g r a i n e d carbonate m i n e r a l s which developed blades up t o 3 cm l o n g . I n f l u x of s i l i c a r e p l a c e d carbonate blades w i t h t r a n s l u c e n t to white c h a l c e d o n i c quartz and rimmed b r e c c i a t e d fragments. Patches of r h y o l i t e (Eo 7) and c r y s t a l t u f f (Eo 6) were then r e p l a c e d by massive f i n e - g r a i n e d white q u a r t z . White c o l l o f o r m c h a l c e d o n i c v e i n l e t s c r o s s c u t the e a r l i e r f a b r i c s 76 WEST H A L F FIGURE 3.25: Q u a l i t i t i v e a l t e r a t i o n map of the Wolf p r o s p e c t . Zone of h i g h a r g i l l i c a l t e r a t i o n are i n d i c a t e d by hatched l i n e s ; advanced a r g i l l i c a l t e r a t i o n i s i n d i c a t e d by c r o s s h a t c h i n g . A) west h a l f , and B) e a s t h a l f . 77 E A S T H A L F FIGURE 3.25: Q u a l i t i t i v e a l t e r a t i o n map of the Wolf p r o s p e c t . Zone of h i g h a r g i l l i c a l t e r a t i o n are i n d i c a t e d by hatched l i n e s ; advanced a r g i l l i c a l t e r a t i o n i s i n d i c a t e d by c r o s s h a t c h i n g . A) west h a l f , and B) e a s t h a l f . TABLE 3.6: Estimated p a r a g e n e t i c sequence o f hydrothermal events a t the Wolf prospect, c e n t r a l B r i t i s h Columbia (modified from Cann, 1984). VEIN OR BRECCIA PHASE HYDROTHERMAL EVENT YOUNGEST 8 Black m a t r i x pebble b r e c c i a 7 Drusy quartz f i l l s c a v i t i e s , cockade quartz t e x t u r e d v e i n l e t s 6 Massive, m i l k y white quartz v e i n s up t o 2 m wide 5 Chalcedonic v e i n i n g and v e i n selvages 4 Massive replacement o f v o l c a n i c rock and c a l c i t e b lades by f i n e - g r a i n e d quartz 3 Rimming of b r e c c i a fragments by chalcedony and f i n e -g r a i n e d quartz 2 B r e c c i a t i o n o f v o l c a n i c s and growth of carbonate blades i n open c a v i t i e s OLDEST 1 Replacement of r h y o l i t e fragments w i t h b l a c k c h a l c e -dony and were i n t u r n c r o s s c u t by massive white quartz v e i n s up t o 2 m wide. F i n a l l y , c l e a r , c o l o u r l e s s , well-formed, drusy quartz i n f i l l e d c a v i t i e s c o n t a i n i n g r e p l a c e d carbonate blades ( P l a t e 3.12) and formed 1-2 mm v e i n l e t s w i t h cockade t e x t u r e . H e t e r o l i t h i c b r e c c i a s w i t h a b l a c k v o l c a n i c matrix (Eog) c r o s s c u t p r e v i o u s hydrothermal f e a t u r e s . The quartz-carbonate t e x t u r e s a t Wolf are s i m i l a r t o those d e t a i l e d by McDonald (1987) a t Mt. Skukum, south-c e n t r a l Yukon T e r r i t o r y . At Wolf t e x t u r e s more c l e a r l y demonstrated t h a t quartz c r y s t a l i n f i l l i n g between r e p l a c e d carbonate blades i s a l a t e r f e a t u r e ( P l a t e 3.12). 3.5.3 ORE PETROLOGY Gold and s i l v e r m i n e r a l i z a t i o n i s a s s o c i a t e d w i t h : (1) the c h a l c e d o n i c phase t h a t commonly rims b r e c c i a t e d fragments (phase 3: Table 3.6), (2) the massive replacement of v o l c a n i c s and the formation of bladed quartz-carbonate v e i n s (phase 4, Table 3.6), and (3) the c h a l e d o n i c v e i n i n g and v e i n selvages (phase 5, Table 3.6). These r e l a t i o n s h i p s are i n f e r r e d from m i c r o s c o p i c s t u d i e s and c o r r e l a t i o n of h i g h e s t g o l d grades with t e x t u r e s . Ore m i n e r a l s i n v e i n s are micron s i z e d and commonly not observed m e g a s c o p i c a l l y . R e s u l t s of scanning e l e c t r o n microscope (SEM) s t u d i e s undertaken by Cann (1984) and the w r i t e r are o u t l i n e d below. Electrum (Au,Ag; F i g . 3.26) occurs as f r e e g r a i n s from 5-10 u up t o 30 u i n diameter ( P l a t e 3.13). I t i s a l s o found as 2-3 u b l e b s i n p y r i t e ( P l a t e 3.14). 80 FIGURE 3.26: Scanning e l e c t r o n microscope energy d i s p e r s i v e peaks of electrum (Au, Ag) i n quartz-cJarbonate v e i n s of the Ridge zone ( F i g s . 3.18, 3.19 and 3.24), Wolf prospect. 81 10M PLATE 3.13 Photomicrograph o f e l e c t r u m i n a q u a r t z - c a r b o n a t e v e i n from t h e Ridge zone. Sample KATR9-1, Wolf p r o s p e c t . B a c k - s c a t t e r e d e l e c t r o n image. 82 PLATE 3.14: Photomicrograph o f e l e c t r u m w i t h i n p y r i t e cubes i n a q u a r t z - c a r b o n a t e v e i n from the Ridge zone. Sample KATR9-1, Wolf p r o s p e c t . B a c k - s c a t t e r e d e l e c t r o n image 40M PLATE 3.15: Photomicrograph o f n a t i v e s i l v e r i n a q u a r t z - c a r b o n a t e v e i n from t h e Ridge zone. Sample"KATR9-1, Wolf p r o s p e c t . B a c k - s c a t t e r e d e l e c t r o n image. Native S i l v e r (Ag) occurs as f r e e g r a i n s v a r y i n g from 3-9 u up t o 20 u i n l e n g t h ( P l a t e 3.15). I t a l s o occurs i n electrum (see g o l d above). A g u i l a r i t e (Ag 4SeS), naummannite (Ag 2Se) and/or a c a n t h i t e (AgS 2) are probably p r e s e n t s i n c e peaks of Se and S were d e t e c t e d i n energy d i s p e r s i v e e l e c t r o n microscope scans ( F i g . 3.27). Pyrite (Fe 2S) occurs as euhedral d i s s e m i n a t i o n s (up t o 1 mm) i n r h y o l i t e (Eo 7) and r h y o l i t e porphyry (Eo 9) on the Ridge and Pond zones. I t c o n t a i n s g r a i n s of e l e c t r u m up t o 2 u i n diameter. C h a l c o p y r i t e (Cu 5FeS 2) occurs as r a r e d i s s e m i n a t i o n s (up t o 1 mm across) i n r h y o l i t e (Eo 7) on the Ridge zone. Cubic g r a i n s of p y r i t e can be surrounded by i r r e g u l a r c h a l c o p y r i t e g r a i n s with secondary rims of s i l v e r - r i c h digenite ( C u 9 S 5 ; Cann, 1984). Galena (PbS) has been d e t e c t e d i n one sample as a d i s c r e t e g r a i n 5-10 u i n diameter. A r g i l l i c a l t e r a t i o n has been q u a n t i t a t i v e l y estimated ( F i g . 3.25) f o r the Wolf p r o p e r t y . Zones of h i g h t o i n t e n s e c l a y a l t e r a t i o n occur w i t h m i n e r a l i z e d zones o u t l i n e d i n s e c t i o n 3.5.1. Q u a l i t a t i v e X-ray d i f f r a c t i o n p a t t e r n s were used t o d e f i n e the a l t e r a t i o n m i n e r a l assemblage a t Wolf. Seven samples taken from d r i l l core on the Ridge and Pond zones were analysed u s i n g standard techniques a t The U n i v e r s i t y of B r i t i s h Columbia. M i n e r a l s were i d e n t i f i e d (Table 3.7) 84 FIGURE 3.27: Scanning e l e c t r o n microscope energy d i s p e r s i v e peaks r e p r e s e n t i n g one o r a combination of a g u i l a r i t e (Ag 4SeS), naummannite (Ag 2Se), or a c a n t h i t e (AgS 2) i n quartz-carbonate v e i n s of the Ridge zone ( F i g s . 3.18, 3.19 and 3.24), Wolf p r o s p e c t . TABLE 3.7: A l t e r a t i o n m i n e r a l s i n rocks o f the Ridge and Pond zones determined by X-ray d i f f r a c t i o n a n a l y s es o f r e p r e s e n t a t i v e specimens a t the Wolf pro s p e c t , c e n t r a l B r i t i s h Columbia. Numbers i n t a b l e i n d i c a t e the r e l a t i v e abundance o f the mi n e r a l ; 1 = most abundant, 4 = l e a s t abundant. Sample l o c a t i o n s are i n Fi g u r e 3.5. SAMPLE NUMBER UNIT NUMBER ALTERATION MINERAL1 OR PL MU KA MM CL IL KA1-1 E o 7 1 2 3 KA2-1 E o 7 2 1 3 KA3-6 EOy 4 1 2 3 KA4-9 E o 9 1 3 2 KA5-13 E o 7 1 2 KA6-12 EOg 1 KA6-17 EOg 2 1 3 1. A l t e r a t i o n m i n e r a l a b b r e v i a t i o n s : OR = o r t h o c l a s e , PL = p l a g i o c l a s e , MU = muscovite, KA = k a o l i n i t e , MM = mo n t m o r i l l o n i t e , CL = c h l o r i t e , I L = i l l i t e . based on d i f f r a c t i o n c h a r t peak h e i g h t . W a l l r o c k a l t e r a t i o n b o r d e r i n g the s i l i c i f i e d zones near v e i n s i s t y p i c a l l y a r g i l l i c or s e r i c i t i c . C h l o r i t e and K - f e l d s p a r were a l s o d e t e c t e d adjacent t o v e i n s (Table 3.7). 3.5.4 METAL DISTRIBUTION Metal d i s t r i b u t i o n p a t t e r n s were examined u s i n g elements commonly a s s o c i a t e d with epithermal d e p o s i t s . These i n c l u d e d 25 As, Ba, S and Sb v a l u e s from the geochemical sample s u i t e (Table 3.8A) as w e l l as 373 Au and Ag v a l u e s (Table 3.8B; Cann, 1984; Holmgren and Cann, 1985). Data p l o t t e d on l o g a r i t h m i c p r o b a b i l i t y paper ( F i g . 3.28) were p a r t i t i o n e d i n t o r e s p e c t i v e p o p u l a t i o n s u s i n g the procedure o u t l i n e d by S i n c l a i r (1976). The means and standard d e v i a t i o n s f o r p a r t i t i o n e d p o p u l a t i o n s are i n Table 3.9. Ba, S and Sb c o n s i s t of mixtures of two lognormal d i s t r i b u t i o n s . Au, Ag and As r e p r e s e n t s i n g l e lognormal d i s t r i b u t i o n s . The Wolf p r o p e r t y i s c h a r a c t e r i z e d by g o l d t o s i l v e r r a t i o s of 1:20 based on the means of these p o p u l a t i o n s . 3.5.5 DISCUSSION The Wolf prospect i s t y p i f i e d by p r e c i o u s metal m i n e r a l i z a t i o n hosted i n zones of s i l i c i f i e d r h y o l i t e and r h y o l i t e porphyry, quartz and r h y o l i t e b r e c c i a s , and quartz v e i n s . Formation of open spaces by b l o c k f a u l t i n g and doming a c t e d as c o n d u i t s , and focused hydrothermal f l u i d 87 TABLE 3.8a: Trace element chemistry o f As, Ba, S and Sb from rocks o f the Wolf p r o p e r t y sample s u i t e 1 . SAMPLE ELEMENT NUMBER AS Ba S Sb ppm ppm ppm ppm KA009 26 50 92 2 KA029 12 47 67 2 KA066 11 261 68 1 KA067 15 588 163 4 KA077 20 24 69 1 KA078 10 25 51 2 KA087 15 79 144 2 KA090 14 500 66 3 KA104 32 68 72 4 KA106 11 163 98 -3 KA108 6 974 74 2 KA112 43 42 89 6 KA128 55 463 150 0 KA133 10 155 77 3 KA135 47 263 153 0 KA141 42 46 79 8 KA163 7 30 48 2 KA178 2 321 125 2 KA184 10 55 73 3 KA195 4 462 114 2 KA200 11 156 94 1 KA220 21 63 86 7 KA221 14 32 58 12 KADDH3-6 48 12 114 4 KADDH4-7 23 182 83 4 1. Analyses were obtained from Midland E a r t h S c i e n c e A s s o c i a t e s , Nottingham, U.K. TABLE 3 . 8 b : T r a c e e l ement c h e m i s t r y o f Ag and Au from r o c k s o f t he W o l f p r o s p e c t , c e n t r a l B r i t i s h C o l u m b i a ( f rom Holmgren and Cann, 1985 ) . S i l v e r a n a l y s e s a r e i n p a r t s pe r m i l l i o n ; g o l d a n a l y s e s i n p a r t s per b i l l i o n . SAMPLE SOURCE'1 Ag Au NUMBER (ppm) (ppb) G - 1302 ACME G - 1303 ACME G - 1304 ACME G - 1305 ACME G - 1306 ACME G - 1307 ACME G - 1308 ACME G - 1309 ACME G - 1310 ACME G - 1311 ACME G - 1312 ACME G - 1313 ACME G - 1314 ACME G - 1315 ACME G - 1316 ACME G - 1317 ACME G - 1318 ACME G - 1319 ACME G - 1320 ACME G- 1321 ACME G- 1322 ACME G- 1323 ACME G- 1324 ACME G- 1325 ACME G- 1326 ACME G- 1327 ACME G- 1328 ACME G- 1331 ACME G- 1332 ACME G- 1333 ACME G-•1334 ACME G-•1335 ACME G-•1329 ACME G-•1330 ACME G-•1336 ACME G-•1337 ACME G-•1338 ACME G-•1339 ACME G-•1340 ACME G--1341 ACME G--1342 ACME G--1343 ACME G--1344 ACME G--1345 ACME G--1346 ACME 0. 7 10 0. 4 25 0. 4 5 18. 3 2630 0 . 2 30 0. 7 75 4 . 3 250 3. 8 475 0. 8 50 0. 5 40 0. 9 130 0. .5 40 0. 7 25 0. 4 25 0. . 9 5 0. .3 5 0. , 1 5 6. .2 1510 54. , 7 7100 63. .7 5840 7 .  1 430 0. . 4 25 0. , 4 5 0, ,2 15 0. .2 5 1, ,2 25 0. .9 40 0, .3 55 0, .3 65 1 .3 165 4 .4 210 0. .2 5 0. .2 5 0 . 1 5 0 .5 20 0 . 1 5 0 .6 15 0 . 1 20 0 . 1 5 0 .6 125 1 . 1 10 0 . 4 . 25 5 .9 430 0 .5 15 0 .3 20 TABLE 3 . 8 b : ( c o n t i n u e d p 2 . ) G - 1347. ACME G - 1348 . ACME G - 1349 ACME G - 1350 ACME G - 1351 ACME G - 1352 ACME G - 1353 ACME G - 1354 ACME G - 1355 ACME G - 1356 ACME G - 1357 ACME G - 1358 ACME G - 1359 ACME G - 1360 ACME G - 1361 ACME G - 1362 ACME G - 1363 ACME G - 1364 ACME G - 1365 ACME G - 1366 ACME G - 1367 ACME G - 1368 ACME G - 1369 ACME G - 1370 ACME G - 1371 ACME G - 1372 ACME G - 1373 ACME G - 1374 ACME G - 1375 ACME G - 1376 ACME G - 1377 ACME G - 1378 ACME G - 1379 ACME G - 1380 ACME G - 1381 ACME G - 1382 ACME G - 1383 ACME G - 1384 ACME G - 1385 ACME G - 1386 ACME G - 1387 ACME G - 1388 ACME G - 1389 ACME G - 1390 ACME G - 1391 ACME G - 1392 ACME G - 1393 ACME G - 1394 ACME G- 1395 ACME G- 1396 ACME G- 1397 ACME G- 1398 ACME G-•1399 ACME 0 . 5 . 20 0. 2 5 0. 8 25 0 . 1 20 0 . 1 5 0 . 1 30 0. 1 5 0. 1 5 0. 2 5 4. 1 330 1. 4 85 2 . 4 70 1. 2 130 0. 4 25 0 . 1 40 0. 1 15 0. 2 20 0. 8 105 0. 4 50 1. 1 60 0. 1 10 0. 1 5 0. 1 35 0. 1 25 0. 7 50 0. 1 5 0. 4 5 0. 3 10 0. 6 60 1. 5 155 1. 8 140 0. 6 100 1. 2 95 0. 8 20 1. 6 245 0. 5 5 0. 5 25 1. 6 95 1. 1 55 1. 7 60 0. 6 65 0. 3 30 2 160 3. 3 415 4. .7 620 12. 6 985 1. .7 280 1. 2 125 0. .8 70 0. 2 15 9. .7 565 1. . 3 25 0. . 4 . 20 TABLE 3 . 8 b : ( c o n t i n u e d p 3 . ) G-1400 G-1451 G-1452 G-1453 G-1454 G-1455 G-1456 G-1457 G-1458 G-1459 G-1460 G-1461 G-1462 G-1463 G-1464 G-1465 G-1466 G-1467 G-1468 G-1469 G-1470 G-1471 G-1472 G-1473 G-1474 G-1475 G-1476 G-1477 G-1478 G-1479 G-1480 G-1481 G-1482 G-1483 G-2601 G-2602 G-2603 G-2604 G-2605 G-3606 G-2607 G-2608 G-2609 G-2610 G-2611 G-2612 G-1613 G-2614 G-2615 G-2616 G-2617 G-2618 G-2619 ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME ACME 2 1.6 0. 7 1. 1 1.8 0 .6 0 .6 0. 0 0" 0 0 0. 0 0. 0.8 2 .2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0. 0. 0. 0. 0. 0. 0 . 0. .4 .3 .2 . 1 .2 .3 . 1 . 1 .2 .2 . 1 . 1 . 1 . 1 .2 . 1 .3 .5 .7 2 2 6 1 3 4 2 2 0 .2 2 .7 0 0 0. 0. 0. 10 585 60 25 70 55 5 20 40 5 5 5 5 5 5 165 5 5 5 10 5 5 5 5 5 5 5 5 5 5 5 5 5 5 65 250 18 20 34 5 3 7 4 8 3 20 2 3 43 27 4 140 28 TABLE 3 . 8 b : ( c o n t i n u e d p 4 . ) G-2520 ACME 1 17 G-2621 ACME 0. .9 11 G-2622 ACME 0 , . 6 9 G-2623 ACME 0. .8 45 G-2624 ACME 1 47 G-2625 ACME 0, .5 39 G-2626 ACME 0, . 1 40 G-2627 ACME 0. . 7 17 G-2628 ACME 3, .2 51 G-2629 ACME 2, .3 22 G-2630 ACME 1. ,5 23 G-2631 ACME 0. .9 29 G-2632 ACME 0. .5 25 G-2633 ACME 1, , 1 1 G-2634 ACME 0. .8 15 G-2635 ACME 2. .6 14 G-2636 ACME 2. ,2 32 G-2637 ACME 7 . .4 2 G-2638 ACME 2. . 1 4 G-2639 ACME 3. .5 14 G-2640 ACME 3 12 G-2641 ACME 1. . 4 12 G-2642 ACME 0. .4 35 G-2643 ACME 0, .6 26 G-2644 ACME 0. , 1 24 G-2645 ACME 0, . 1 10 G-2646 ACME 0. . 1 16 G-2647 ACME 0. .9 15 G-2648 ACME 0. . 3 23 G-2649 ACME 0. .3 7 G-2650 ACME 1. .5 35 G-2651 ACME 12. .2 170 G-2652 ACME 1 27 G-2653 ACME 0. .2 19 G-2654 ACME 0. .3 14 G-2655 ACME 1, .3 26 G-2656 ACME 0, .4 39 G-2657 ACME 0. . 3 42 G-2658 ACME 0. .8 40 G-2659 . ACME 0, .5 29 G-2660 ACME 0, .2 10 G-2661 ACME 0, .5 9 G-2662 ACME 0, .4 9 G-2663 ACME 0, . 4 12 G-2664 ACME 0, .2 17 G-2665 ACME 0. .3 25 G-2666 ACME 0. .3 11 G-2667 ACME 0. .3 13 G-2668 ACME 0, .5 22 G-2669 ACME 0. .6 14 G-2670 ACME 0. . 4 36 G-2671 ACME 0 .6 17 G-2672 ACME 0. .5 18 TABLE 3 . 8 b : ( c o n t i n u e d p 5 . ) G-2673, ACME 0. . 2 G-2674 ACME 0. . 3 25 G-2675 ACME 0 , . 3 7 G-2676 ACME 0. . 2 4 G-2677 ACME 10. . 3 340 G-2678 ACME 0, .2 28 G-2679 ACME 0. . 4 65 G-2680 ACME 0. .6 42 G-2681 ACME 0. .8 4 G-2682 ACME 0, .6 5 G-2683 ACME 0 , .7 36 G-2684 ACME 0. .3 16 G-2685 ACME 0. .6 85 G-2686 ACME • .0 . . 4 44 G-2687 ACME 1 38 G-2688 ACME 0. .7 42 G-2689 ACME 0 , . 3 9 G-2690 ACME 0, .6 44 G-2691 ACME 0. . 4 455 G-2692 ACME . 0, . 4 59 G-2693 ACME 20, .5 2100 G-2694 ACME 0. .4 19 G-2695 ACME 0. . 3 59 G-2696 ACME 1 85 G-2697 ACME 0. . 3 40 G-2698 ACME 0. .2 32 G-2699 CDN 1. ,3 5 G-2700 CDN 1, . 4 15 G-2701 CDN 0, ,4 40 G-2702 CDN 1. . 4 35 G-2703 CDN 0. , 1 25 G-2704 CDN 0. . 1 60 G-2705 CDN 1. ,5 170 G-2706 CDN 0. .4 185 G-2707 CDN 1. ,3 170 G-2708 CDN 0. . 1 30 G-2709 CDN 3. .4 330 G-2710 CDN 3. , 7 210 G-2711 CDN 1. , 4 75 G-2712 CDN 1. .2 140 G-2713 CDN 1. ,3 90 G-1679 ACME 0. ,7 230 G-1680 ACME 1. ,8 290 G-1681 ACME 0. ,9 135 G-1682 ACME 0. .9 190 G-1683 ACME 1. , 1 280 G-1684 ACME 2. , 1 190 G-2714 ACME 1 105 G-2715 ACME 0. ,9 210 G-2716 ACME 1. , 3 110 G-2717 ACME 1. .5 225 G-2718 ACME 15.. , 1 1800 G-2719 ACME 3. .4 610 TABLE 3 . 8 b : ( c o n t i n u e d p 6 . ) G - 2720 ACME G - 2721 ACME G - 2722 ACME G - 2723 ACME G - 2724 ACME G - 2725 ACME G - 2726 ACME G - 2727 ACME G - 2728 ACME G- 2729 ACME G- 2730 ACME G- 2731 ACME G- 2732 ACME G- 2733 ACME G- 2734 ACME G- 2735 ACME G- 2736 ACME G- 2737 ACME G - 2738 ACME G- 2739 ACME G- 2740 ACME G- 2741 ACME G- 2742 ACME G-•2743 ACME G-•2744 ACME G-•2745 ACME G-•2746 ACME G-•2747 ACME G-•2748 ACME G-•2749 ACME G-•2750 ACME G-•2765 ACME G-•2766 ACME G-•2767 ACME G--2768 ACME G-•2769 ACME G--.277 0 ACME G--2771 ACME G--2772 ACME G--2773 ACME G--2774 ACME G--2775 ACME G--2776 ACME G--2777 ACME G--2778 ACME G--2779 ACME G--2780 ACME G--2781 ACME G--2782 ACME G--2783 ACME G--2784 ACME G--2785 ACME G--2786 ACME 1. 6 250 3. 2 360 3. 7 470 6. 1 940 6 . 7 680 o 7 480 0 . 3 35 1. 3 265 2. 5 . 320 11. 5 1800 2 . 2 850 1. 4 230 2. 3 225 2. 1 235 1. 6 40 0. 4 30 3. 2 330 3. 8 410 1. .7 240 4. .5 985 6 1550 4. .7 200 1. ,3 90 0. ,4 16 2 . .2 75 12. .2 780 6. , 1 310 2 310 1. ,6 165 1. ,5 250 1. .4 265 0, .7 5 1. .2 10 0. .2 2 0. .2 5 0. . 1 2 0 .4 3 0. .4 2 0, . 1 5 0. .7 2 0 .2 1 0. . 1 1 0. .6 2 0. .3 1 0 . 1 1 0 . 3 2 0 . 1 1 0 . 4 2 2 .5 7 0 .2 2 0 . 2 3 1 2 0 .2 1 TABLE 3 . 8 b : ( c o n t i n u e d p 7 . ) G-2787. ACME 0 . 1 1 G-2788 ACME 0 . 2 1 G-2789 ACME 0 . 1 2 G-2790 ACME 0 . 1 4 G-2791 ACME 0 . 2 1 G-2792 ACME 0 . 1 1 G-2793 ACME 0 .3 11 G-2794 ACME 0 . 1 2 G-2795 ACME 0 . 1 1 G-2796 ACME 0 . 1 1 G-2797 ACME 0 . 1 1 G-2798 ACME 0 . 1 4 G-2799 ACME 1 . 1 9 G-2800 ACME 0 . 1 1 G-3301 ACME 2 . 3 450 G-3302 ACME 2 .5 730 G-3303 ACME 0 .2 9 G-3304 ACME 4 .9 430 G-3305 ACME 38 .6 2200 G-3306 ACME 1 .8 270 G-3307 ACME 2 .2 300 G-3308 ACME 6 250 G-3309 ACME 5 .9 500 G-3310 ACME 6 ,7 290 G-3311 ACME 8 .4 510 G-3312 ACME 3 .6 980 G-3313 ACME 12 .5 2000 G-3314 ACME 11 . 5 2100 G-3315 ACME 1 . 1 150 G-3316 ACME 5 .6 930 G-3317 ACME 0 .6 90 G-3318 ACME 3 .4 750 G-3319 ACME 0 .9 155 G-3320 ACME 1 .2 310 G-3321 ACME 0 .5 115 G-3322 ACME 0 .6 90 G-3323 ACME 3 .3 1600 G-3324 ACME 2 .9 460 G-3325 ACME 1 .2 100 G-3326 ACME 12 800 G-3327 ACME 1 .8 75 G-3328 ACME 2 . 3 410 G-3329 ACME 7 .7 700 G-3330 ACME 1 .6 100 G-3331 ACME 5 .9 290 G-3332 ACME ' 36 .7 1300 G-3333 ACME 2 .7 180 G-3334 ACME 0 .8 90 G-3335 ACME 1 .2 100 G-1685 ACME 1 .5 155 G-1686 ACME 1 210 G-1687 ACME 1 .2 135 TABLE 3 . 8 b : ( c o n t i n u e d p 8 . ) TABLE 3.8b: (continued p8.) 95 G-1688 ACME 0. .3 80 G-1689 ACME 0. .2 65 G-1690 ACME 0. . 1 75 G-1691 ACME 0. , 1 7 G-1692 ACME 0, . 1 8 G-1693 ACME 0. .6 90 G-1694 ACME 1. .3 110 G-1695 ACME 0. ,3 125 G-1696 ACME 1 24 G-1697 ACME 0. ,3 130 I. Geochemical ICP analyses were obtained from Acme A n a l y t i c a l Laboratories, Vancouver, and CDN Resource Laboratories Ltd., Delta, B.C. Samples were digested with 3 ml 3-1-2 HC1-HN03-H20 at 95 degrees for one hour and d i l i t e d to 10 ml with water. 96 Cumulative Percent FIGURE 3.28: L o g a r i t h m i c p r o b a b i l i t y p l o t s i l l u s t r a t i n g d i s t r i b u t i o n o f : A = Au, B = Ag, C = S, D = S b , E = B from the Wolf p r o s p e c t . Means and standar d d e v i a t i o n s are i n Tab l e 3.9. 97 Cumulative Percent E 0.2 . 0 N=25 \ \ ""X A=30% \ \ \ . x=0.96 V \ \ . s = ±0.76 B=70% \ X - - 1 . 6 . \ 3 = ± 2.4 \ 2 10 20 30 40 50 60 70 80 90 95 98 Cumulative Percent FIGURE 3.28: Lo g a r i t h m i c p r o b a b i l i t y p l o t s i l l u s t r a t i n g d i s t r i b u t i o n o f : A = Au, B = Ag, C = S, D = Sb, E = B from the Wolf p r o s p e c t . Means and standard d e v i a t i o n s are i n Table 3 . 9 . 98 2 10 20 30 40 50 60 70 80 90 95 98 Cumulative Percent FIGURE 3.28: L o g a r i t h m i c p r o b a b i l i t y p l o t s i l l u s t r a t i n g d i s t r i b u t i o n o f : A = Au, B = Ag, C = S , D = S b , E = B from the Wolf p r o s p e c t . Means and st a n d a r d d e v i a t i o n s are i n Tab l e 3.9. 99 TABLE 3.9: Means and standard d e v i a t i o n s determined g r a p h i c a l l y f o r p a r t i t i o n e d metal v a l u e s a t the Wolf prospect, c e n t r a l B r i t i s h Columbia. ELEMENT UNITS POPULATION H1 b 2 b+s 3 b-s 4 AU ppb A 100 31.6 251 4.47 Ag ppm A 100 0.63 - 2.82 0.13 As ppm A 100 16.6 35.5 7.59 Ba ppm A 45 300 750 126 ppm B 55 23.7 178 3.2 S ppm A 40 158 214 115 ppm -B 60 42 200 8.9 Sb ppm A 30 9.1 15.1 5.25 ppm B 70 0.7 40 0. 13 1. % of data i n p o p u l a t i o n 2. a n t i l o g o f mean of lognormal p o p u l a t i o n 3. a n t i l o g o f mean p l u s one standard d e v i a t i o n o f lognormal p o p u l a t i o n 4. a n t i l o g of mean p l u s one standard d e v i a t i o n o f lognormal p o p u l a t i o n 100 d e p o s i t i o n . At l e a s t e i g h t d i s t i n c t phases of v e i n i n g and b r e c c i a t i o n are r e c o g n i s e d (Table 3.6). A s s o c i a t i o n of b r e c c i a t e x t u r e s , vuggy v e i n t e x t u r e s , chalcedony and m i n e r a l i z a t i o n i m p l i e s t h a t v e i n emplacement was e x p l o s i v e and a t shallow l e v e l s . Evidence f o r b o i l i n g of hydrothermal f l u i d s i s documented at Wolf by study of f l u i d i n c l u s i o n s i n quartz v e i n s and b r e c c i a s ( s e c t i o n 3.6). B o i l i n g r e l e a s e s v o l a t i l e s such as C0 2, H 2S and H 2Q promoting s i l i c a s a t u r a t i o n ( F o u r n i e r , 1985) and a r g i l l i c a l t e r a t i o n i n the w a l l r o c k adjacent t o s i l i c i f i e d zones. Abundant chalcedony i m p l i e s t h a t hydrothermal f l u i d s were s i l i c a s a t u r a t e d . Rapid p r e c i p i t a t i o n of g o l d from s i l i c a s a t u r a t e d hydrothermal f l u i d s has been r e l a t e d t o . b o i l i n g i n s e v e r a l e p i t h e r m a l d e p o s i t s (Barnes, 1979; Henley and Brown, 1985). N a t i v e s i l v e r and electrum of micron s i z e are a s s o c i a t e d w i t h p y r i t e and s i l v e r s u l p h o s a l t s i n s i l i c i f i e d zones. P r o b a b i l i t y graphs i n d i c a t e t h a t the p a r t i t i t i o n i n g of Au and Ag i n t o a s i n g l e p o p u l a t i o n c o n t r a s t s w i t h p a r t i t i o n i n g of other elements. I t should be noted t h a t Au and Ag analyses are from a l a r g e p o p u l a t i o n (N = 373) whereas As, Ba, S and Sb are from a s m a l l one (N = 25). The d i f f e r e n c e i n p a r t i t i o n i n g of the Au and Ag, compared t o Ba, Sb and S c o u l d be r e l a t e d t o c o n t r a s t i n g p o p u l a t i o n s i z e and/or sampling of d i f f e r e n t p o p u l a t i o n s . I f a d i f f e r e n c e i n number of p o p u l a t i o n s e x i s t s , Ba, S and Sb c o u l d r e p r e s e n t background v a l u e s i n the Ootsa Lake Group as w e l l as anomalous v a l u e s r e l a t e d t o m i n e r a l i z a t i o n a t Wolf. Background g o l d and s i l v e r v a l u e s i n the Ootsa Lake Group on the W h i t e s a i l Lake sheet are markedly low (Diakow, o r a l comm., 1988). The Au and Ag v a l u e s a t Wolf are from samples i n known areas of m i n e r a l i z a t i o n and probably r e p r e s e n t anomalous p o p u l a t i o n s r e l a t e d t o hydrothermal processes r a t h e r than background p o p u l a t i o n s . Because As does not c o r r e l a t e w i t h the other elements i t might not be a r e l i a b l e geochemical p a t h f i n d e r a t Wolf. G e o l o g i c s e t t i n g , v e i n and b r e c c i a t e x t u r e s , a l t e r a t i o n and metal d i s t r i b u t i o n p a t t e r n s a t Wolf resemble those of a low sulphur h o t - s p r i n g or s i l i c i f i e d stockwork d e p o s i t (Berger and Eimon, 1983; Silverman and Berger, 1985). Examples of t h i s type of a d e p o s i t i n c l u d e Round Mountain, Nevada; B o r e a l i s , Nevada; and McLaughlin, C a l i f o r n i a . 3.6. HYDROTHERMAL ENVIRONMENT OF DEPOSITION F l u i d i n c l u s i o n and oxygen i s o t o p e s t u d i e s examine some f e a t u r e s of the hydrothermal environment of d e p o s i t i o n a t Wolf. S p e c i f i c a l l y , these s t u d i e s c o n s t r a i n : (1) the temperature and s a l i n i t y o f the d e p o s i t i o n a l f l u i d , (2) the oxygen and hydrogen i s o t o p i c composition and source of the hydrothermal f l u i d , (3) the depth of m i n e r a l emplacement, (4) the water t o rock r a t i o i n the hydrothermal system, and (5) the f l u i d e v o l u t i o n of the system w i t h time. D e f i n i n g the hydrothermal environment of d e p o s i t i o n a t Wolf a l l o w s comparison t o s i m i l a r d e p o s i t s hosted i n Eocene v o l c a n i c 102 rocks i n B r i t i s h Columbia, as w e l l as t o w o r l d - c l a s s d e p o s i t s . 3.6.1. FLUID INCLUSION STUDY The f l u i d i n c l u s i o n study of 17 v e i n and b r e c c i a samples from f i v e zones on the Wolf p r o p e r t y a l l o w s estimates o f : (1) the temperature of d e p o s i t i o n of hydrothermal f l u i d s , (2) the s a l i n i t y of the hydrothermal f l u i d s , (3) the composition of vapour or s o l i d phases present, (4) the s i g n i f i c a n c e of b o i l i n g as a p r e c i p i t a t i o n mechanism i n the hydrothermal system, and (5) the depth of m i n e r a l emplacement. Samples mainly taken from d r i l l core on the Ridge and Pond zones and from the Lookout, Chopper Pad and East zones allow r e p r e s e n t a t i o n of ore f l u i d s over a s i g n i f i c a n t v e r t i c a l and l a t e r a l e xtent. Sample l o c a t i o n s are p l o t t e d i n F i g u r e s 3.29 and 3.30, d e t a i l e d d e s c r i p t i o n s of samples are i n Table 3.10. 3.6.1.1. Sample p r e p a r a t i o n and a n a l y s i s Seventeen doubly p o l i s h e d t h i n s e c t i o n s were prepared c l o s e l y f o l l o w i n g the procedure o u t l i n e d by H o l l a n d e t a l . (1978). S e c t i o n s were cut 50 t o 100 urn t h i c k and p o l i s h e d w i t h t i n oxide. Of the o r i g i n a l 17 samples, usable i n c l u s i o n s were a v a i l a b l e i n o n l y e i g h t s e c t i o n s . The remaining s e c t i o n s were choked wi t h minute i n c l u s i o n s (< 2 urn across) which c o u l d not be adequately r e s o l v e d a t 1250x m a g n i f i c a t i o n w i t h the p e t r o g r a p h i c microscope. 103 WEST HALF FIGURE 3.29: Sample l o c a t i o n s of s u r f a c e v e i n s used f o r f l u i d i n c l u s i o n analyses from the Wolf p r o s p e c t . A) west h a l f , and B) e a s t h a l f . Sample d e s c r i p t i o n s are i n Table 3.10. 104 FIGURE 3.29: Sample l o c a t i o n s o f s u r f a c e v e i n s used f o r f l u i d i n c l u s i o n a n a l y s e s from the Wolf p r o s p e c t . A) west h a l f , and B) e a s t h a l f . Sample d e s c r i p t i o n s are i n Tab l e 3.10. 1300 -Metres above sea level K A 6 - 2 ' K A 6 - 6 < KA6- I4 I EOo Metres 20 4 0 60 8 0 IOO Ms SI05TONE. TUFFACEOUS SANDSTONE EOl CONGLOMERATE LEGEND E0« ASH TUFF E05 RHYOLITE FLOWS [ED VOLCANIC BRECCIA RHYOLITE PORPHYRY E 0 2 FELSIC LAPILLI TUFF E 0 6 CRYSTAL TUFF E0, 0 QUARTZ PORPHYRY EOs I LITHIC, CRYSTAL TUFFl EO7 RHYOLITE ED ANDESITE FLOWS, FLOW BRECCIA SYMBOLS 2D geological contact; known,assumed MM fault-,known, assumed foliation —"-lineation i s vein, with dip ,„ ., • diamond drill hole(DDH) DDH trace FIGURE 3.30: Sample l o c a t i o n s of v e i n s i n t e r s e c t e d i n d r i l l core at the Ridge and Pond zones used f o r f l u i d i n c l u s i o n analyses, Wolf prospect. Sample d e s c r i p t i o n s are i n Table 3.10. M o U1 TABLE 3.10: D e s c r i p t i o n s o f v e i n samples used f o r f l u i d i n c l u s i o n analyses a t the Wolf p r o p e r t y , c e n t r a l B r i t i s h Columbia. Samples are l o c a t e d i n F i g u r e s 3.29 and 3.30. ZONE SAMPLE VEIN HOST SAMPLE DESCRIPTION NUMBER TYPE ROCK RIDGE RIDGE RIDGE KATR9-1 BLADED RHYOLITE RIDGE RIDGE RIDGE RIDGE POND KA1-1 KA1-2 KA2-2 KA3-4 KA5-5 KA022 KA4-8 BLADED RHYOLITE BLADED RHYOLITE BRECCIA RHYOLITE INFILLS BRECCIA RHYOLITE INFILLS COCKADE RHYOLITE MASSIVE CRYSTAL REPLACE-MENT BLADED RHYOLITE PORPHYRY Densely bladed q u a r t z -carbonate v e i n (blades up t o 2 cm long Myriad o f den s e l y bladed quartz-carbonate v e i n s (blades up t o 5 mm long) Densely bladed q u a r t z -carbonate v e i n l e t (1 cm wide, blades up t o 0.5 cm long) H e t e r o l i t h i c b r e c c i a fragments rimmed by f i n e -g r a i n e d , t r a n s l u c e n t quartz C l e a r , c o l o u r l e s s , f i n e -g r a i n e d quartz rims on r h y o l i t e b r e c c i a fragments Quartz v e i n l e t up t o 2 mm wide rims r h y o l i t e b r e c c i a fragments Replacement of ho s t c r y s t a l t u f f by f i n e s i l i c a w i t h r e l i c t shadows of former m i n e r a l s remaining Bladed quartz-carbonate, rimming of host rock by quartz and drusy quartz c a v i t i e s POND KA4-15 CHALC- RHYOLITE EDONIC PORPHYRY BANDING Banded c h a l c e d o n i c v e i n s s e a l e d by m i l k y white s u c r o s i c quartz 107 TABLE 3.10: (continued) POND KA4-19 QUARTZ RHYOLITE Repeated i n f i l l i n g and s e a l i n g o f v e i n l e t by f i n e - g r a i n e d quartz and chalcedony. POND KA6-2 COCKADE QUARTZ VEIN RHYOLITE PORPHYRY Comb qu a r t z , quartz i n f i l l i n g , c h a l c e d o n i c banding and rimming of v e i n w a l l s by q u a r t z . POND KA6-6 BLADED RHYOLITE PORPHYRY Bladed quartz-carbonate c r o s s c u t by 2mm v e i n l e t s of drusy q u a r t z . POND KA6-14 BLADED RHYOLITE PORPHYRY Densely bladed q u a r t z -carbonate v e i n l e t (blades up t o 0.5 cm l o n g ) . POND KA019 QUARTZ VEIN CRYSTAL TUFF Sample from l a r g e massive, milky-white quartz v e i n . LOOKOUT KA031 BLADED CRYSTAL TUFF Bladed quartz-carbonate w i t h i n broad patch o f milk y white v e i n q u a r t z . CHOPPER PAD KA063 BRECCIA INFILLS RHYOLITE I n f i l l i n g around r h y o l i t e b r e c c i a by c l e a r , t r a n s -l u c e n t f i n e - g r a i n e d quartz EAST KA188 DRUSY RHYOLITE PORPHYRY Drusy quartz f i l l s open c a v i t i e s and l i n e s f r a c t u r e s . F l u i d i n c l u s i o n a n a l y s i s was c a r r i e d out u s i n g a Chiaxmeca h e a t i n g / f r e e z i n g stage. A t o t a l o f 41 f l u i d i n c l u s i o n s were analysed (Table 3.11). Measurements were c o r r e c t e d u s i n g c a l i b r a t i o n curves from McDonald (1987). These curves demonstrate an accuracy of measurement t o w i t h i n 6.7°C with a p r e c i s i o n of 0.6°C (Id) f o r the temperature range -100°C t o +40°C, and t o w i t h i n 5.3°C w i t h a p r e c i s i o n of 2.2°C (lo*) f o r the temperature range +40°C t o +420°C. 3.6.1.2. E r r o r a n a l y s i s Consecutive h e a t i n g and f r e e z i n g runs were made t o t e s t r e p r o d u c i b i l i t y of homogenization and l a s t m e l t i n g temperatures. Heating r a t e s of about 5°C/minute were used t o w i t h i n 30°C of homogenization, a t which time r a t e s were decreased t o l-2°C/minute. Repeated measurements demonstrate a r e p r o d u c i b i l i t y t o w i t h i n 5°C and 2°C f o r homogenization and l a s t m e l t i n g temperatures r e s p e c t i v e l y . 3.6.1.3. F l u i d I n c l u s i o n Petrography F l u i d i n c l u s i o n s were observed from bladed q u a r t z -carbonate v e i n s , cockade quartz v e i n l e t s , drusy quartz l i n e d c a v i t e s and quartz i n f i l l i n g around b r e c c i a t e d fragments (Table 3.11). An estimated p a r a g e n e t i c sequence f o r these phases of v e i n and b r e c c i a d e p o s i t i o n i s i n T a b l e 3.6. R e c o g n i t i o n of these t e x t u r e s allows c l e a r documentation of 109 TABLE 3.11: P e t r o g r a p h i c , homogenization and f r e e z i n g data f o r f l u i d i n c l u s i o n s from quartz v e i n s a t the Wolf prospect, c e n t r a l B r i t i s h Columbia. Sample l o c a t i o n s are i n F i g u r e 3.30 and 3.31. ZONE SAMPLE ELEV VEIN INCLUSION"2 TEMPERATURE NUMBER (m) TYPE TYPE SIZE BS V% HOMG. EUT. LAST RIDGE KATR9-1 1250 BL S 24.6 16.4 5 5 176 PS 16.4 16.4 5 10 288 PS 16.4 16.4 5 10 289 P 24.6 16.4 5 5 270 S 10.9 8.2 5 5 191 S 10.9 8.2 5 5 183 S 8.2 5.5 3 10 180 P 81.9 27.3 10 15 265 PS 24.6 16.4 5 10 267 RIDGE KA3-4 1265 BR P - 16.4 16.4 10 5 250 S 24.6 16.4 10 5 100 PS 24.6 16.4 10 10 285 RIDGE KA022 1240 MR PS 13.7 8.2 5 40 145 PS 13.7 8.2 5 30 145 POND KA4-8 1247 BL P 41.0 32.8 10 2 265 S 65.5 4.1.0 10 2 82 P 16.4 5 10 183 16.4 1. VEIN TYPE: BL = bladed, BR = b r e c c i a i n f i l l i n g , MR = massive replacement, CQ = cockade quartz v e i n l e t , DQ = drusy quartz v e i n l e t . 2. INCLUSION TYPE: P = primary, PS = pseudosecondary, S = secondary. INCLUSION SIZE: maximum by minimum; i n microns. INCLUSION BS: BS = bubble s i z e ; i n microns. INCLUSION V%: V% =* volume percent ( V l / V l + Vv) 3. TEMPERATURE HOMG. = homogenization temperature; °C TEMPERATURE EUT. = e u t e c t i c temperature; °C TEMPERATURE LAST = l a s t m e l t i n g temperature; °C 110 TABLE 3.11: (continued p2.) ZONE SAMPLE ELEV VEIN 1 INCLUSION^ TEMPERATURE3-NUMBER (m) TYPE TYPE SIZE BS V% HOMG. EUT. LAST POND KA4-15 1235 BL P 16.4 5 20 155 16.4 PS 16.4 5 5 16.4 PS 24.6 5 10 145 16.4 POND KA6-6 1245 ,BL S 54.6 10 5 181 16.4 S 16.4 5 10 137 16.4 P 32.8 10 5 262 -26.5 -2.1 24.6 P 16.4 5 10 180 -26.5 -2.3 16.4 POND KA6-2 1250 CQ P 16.4 5 30 162 16.4 P 16.4 5 20 188 10.9 PS 24.6 5 5 170 10.9 S 16.4 5 5 179 10.9 EAST KA188 1250 DQ P 41.0 10 10 249 24.6 PS 57.3 10 2 249 24.6 PS 65.5 10 2 235 16.4 P 81.9 15 2 258 -27 -1.3 32.8 S 65.5 15 5 243 41.0 S 65.5 15 10 242 32.8 S 65.5 15 5 230 41.0 1. VEIN TYPE: BL = bladed, BR = b r e c c i a i n f i l l i n g , MR = massive replacement, CQ = cockade quartz v e i n l e t , DQ = drusy quartz v e i n l e t . 2. INCLUSION TYPE: P = primary, PS = pseudosecondary, S = secondary. INCLUSION SIZE: maximum by minimum; i n microns. INCLUSION BS: BS = bubble s i z e ; i n micron3. INCLUSION V%: V% = volume pe r c e n t ( V l / V l + Vv) 3. TEMPERATURE HOMG. = homogenization temperature; °C TEMPERATURE EUT. = e u t e c t i c temperature; °C TEMPERATURE LAST = l a s t m e l t i n g temperature; °C I l l TABLE 3.11: (continued p3.) ZONE SAMPLE ELEV VEIN 1 INCLUSION 2 TEMPERATURE3-NUMBER (m) TYPE 1 TYPE SIZE BS V% H0M6. EUT. LAST EAST KA188 1250 DQ S 65.5 10 2 253 16.4 P 54.6 15 2 210 54.6 P 81.9 15 10 286 -24 -1.0 49.1 PS 81.9 15 5 162 32.8 PS 24.6 10 5 277 16.4 p 81.9 15 5 264 -28.1 -0.9 32.8 1. VEIN TYPE: BL = » bladed , BR = b r e c c i a i n f i l l i n g , MR = massive replacement, CQ = cockade quartz v e i n l e t , DQ = drusy quartz v e i n l e t . 2. INCLUSION TYPE: P = primary, PS = pseudosecondary, S = secondary. INCLUSION SIZE: maximum by minimum; i n microns. INCLUSION BS: BS = bubble s i z e ; i n microns. INCLUSION V%: V% = volume pe r c e n t ( V l / V l + Vv) 3. TEMPERATURE HOMG. = homogenization temperature; °C TEMPERATURE EUT. = e u t e c t i c temperature; °C TEMPERATURE LAST = l a s t m e l t i n g temperature; °C 112 f l u i d i n c l u s i o n data with r e s p e c t t o hydrothermal events a t Wolf. Primary (P), pseudosecondary (PS), or secondary (S) o r i g i n was i d e n t i f i e d c a r e f u l l y f o r each f l u i d i n c l u s i o n measured from Wolf (Table 3.11). Wherever p o s s i b l e , primary f l u i d i n c l u s i o n s t r a c i n g growth zones i n the quartz c r y s t a l s were measured ( P l a t e 3.16). These i n c l u s i o n s are assumed t o r e p r e s e n t samples of f l u i d s trapped a t the same time of formation as the quartz host. Secondary f l u i d i n c l u s i o n s , l y i n g a long planes c r o s s c u t t i n g c r y s t a l boundaries were a l s o measured ( P l a t e 3.17). These i n c l u s i o n s are p r e s e r v e d i n h e a l e d m i c r o f r a c t u r e s and p r o v i d e i n f o r m a t i o n on f l u i d s p r e s e n t a f t e r growth of the quartz host. Pseudosecondary f l u i d i n c l u s i o n s l y i n g along planes t e r m i n a t i n g a t c r y s t a l boundaries r e p r e s e n t f l u i d s trapped i n f r a c t u r e s d u r i n g growth of the quartz host. Assignment of f l u i d i n c l u s i o n o r i g i n i s c r u c i a l t o i n t e r p r e t a t i o n of f l u i d i n c l u s i o n data w i t h i n a p a r a g e n e t i c framework (Roedder, 1976). Most f l u i d i n c l u s i o n s a t Wolf have two phases w i t h the dominant phase being l i q u i d ( P l a t e 3.18). The most conspicuous s i n g l e f e a t u r e of a l l i n c l u s i o n s s t u d i e d i s a vapour bubble. The diameter of the vapour bubble i n each i n c l u s i o n was measured a t room temperature (Table 3.11) b e f o r e and a f t e r each h e a t i n g so t h a t any leakage induced by subsequent c o o l i n g c o u l d be measured ( c f . H o l l i s t e r e t a l . , 1981). No change i n vapour bubble diameter was observed i n the study. V i s u a l e s t i m a t i o n s of the amount of vapour phase 1 1 3 PLATE 3.16: Photomicrograph o f growth zones i n q u a r t z d e f i n e d by p r i m a r y f l u i d i n c l u s i o n c o n c e n t r a t i o n s . Q u a r t z -c a r b o n a t e v e i n from t h e Pond zone. Sample KA4-8, Wolf p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . PLATE 3.17: Photomicrograph o f p l a n e s o f s e c o n d a r y f l u i d i n c l u s i o n s i n q u a r t z from t h e Pond zone. Sample KA6-2, Wolf p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . PLATE 3.18: Photomicrograph o f t y p i c a l two-phase f l u i d i n c l u s i o n s i n v e i n q u a r t z from t h e Ridge zone. Sample KA022, Wolf p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . present, made by comparison t o a c h a r t i n Roedder (1976), are i n Tab l e 3.11, and vary from 2% to 40% wit h a mode of 10%. Evidence f o r b o i l i n g was observed i n one q u a r t z -carbonate v e i n sample (KA4-8, P l a t e 3.19) where growth zones i n quartz are d e f i n e d by two phase l i q u i d and v a p o u r - r i c h i n c l u s i o n s . The s i z e o f measured f l u i d i n c l u s i o n s ranged from 8.2 urn t o 81.9 urn ac r o s s i n t h e i r l o n g e s t dimension. Most i n c l u s i o n s were l e s s than 30 urn long. Two phase f l u i d i n c l u s i o n s from Wolf were crushed t o t e s t f o r the presence of C0 2 vapour u s i n g methods d e s c r i b e d i n Roedder (1984). C0 2 i s a common v o l a t i l e component i n most f l u i d i n c l u s i o n s i n the epithermal environment (Bodnar e t a l . , 1985); the presence of C0 2 can be r e c o g n i s e d by expansion o f the vapour bubble when the i n c l u s i o n s a re opened by c r u s h i n g a sample t h i c k s e c t i o n i n o i l . The minimum amount of C0 2 r e q u i r e d b e f o r e the vapour bubble w i l l expand d u r i n g c r u s h i n g s t u d i e s i s 0.1 mol p e r c e n t (Bodnar e t a l . , 1985). Evidence of noncondensed gases was not seen d u r i n g c r u s h i n g s t u d i e s from Wolf samples. Thus, l e s s than 0.1 mol percent C0 2 i s present i n the f l u i d i n c l u s i o n s a t Wolf. T h i s i s t y p i c a l f o r most bonanza-type e p i t h e r m a l systems (Bodnar e t a l . , 1985), although the dominant v o l a t i l e component i n most f l u i d i n c l u s i o n s from the epit h e r m a l environment i s C0 2 (Bodnar e t a l . , 1985). 3.6.1.4 F r e e z i n g and h e a t i n g data 116 PLATE 3.19: Photomicrograph o f growth zones i n a q u a r t z c r y s t a l d e f i n e d by p r i m a r y f l u i d i n c l u s i o n c o n c e n t r a t i o n s . P o n d zone. Sample KA4-8, Wolf p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . F r e e z i n g and h e a t i n g s t u d i e s were conducted on the Chiaxmeca stage f o l l o w i n g o p e r a t i n g procedures o u t l i n e d by Bloom (1979). Because f r e e z i n g i s l e s s l i k e l y t o d i s t o r t i n c l u s i o n s i n quartz, a l l o b s e r v a t i o n s were completed i n the f r e e z i n g mode b e f o r e proceeding t o the h e a t i n g phase. A l l i n c l u s i o n s used f o r f r e e z i n g s t u d i e s were super-c o o l e d t o approximately -100°C. Slow h e a t i n g (averaging 2°C/minute) from -100°C t o about +5°C enabled d e t e r m i n a t i o n of the temperature o f i n i t i a l m e l t i n g ( e u t e c t i c temperature, T a b l e a l ) and the temperature o f l a s t m e l t i n g . Due t o the o p a c i t y o f s e v e r a l quartz p l a t e s and the s m a l l s i z e o f many i n c l u s i o n s , f r e e z i n g temperatures and phase changes c o u l d o n l y be observed i n s i x f l u i d i n c l u s i o n s . E u t e c t i c and l a s t m e l t i n g p o i n t s f o r i n c l u s i o n s from each v e i n type are p l o t t e d i n F i g u r e s 3.31 t o 3.32 and summarized i n Tab l e 3.12. E u t e c t i c tempertures, which r e p r e s e n t the f i r s t i c e me l t i n g , range from -24°C t o -28.1°C (Table 3.12). No meaningful d i s t i n c t i o n can be made between e u t e c t i c temperatures from f l u i d i n c l u s i o n s hosted i n drusy or bladed quartz ( F i g . 3.31). L a s t m e l t i n g temperatures range from -0.9°C down t o -2.3°C. F l u i d i n c l u s i o n s hosted i n e a r l y formed bladed quartz y i e l d e d lower l a s t m e l t i n g temperatures, and t h e r e f o r e h i g h e r s a l i n i t i e s , than those hosted i n l a t e r formed drusy quartz ( F i g . 3.32). Homogenization temperatures were determined f o r 41 i n c l u s i o n s from d i f f e r e n t v e i n types (Table 3.13). Heating to U J o z UJ ec or 3 O o o u. o z U l z o CD or < o I N I -cc < 3 0» o U l o < a! 9 i -24 - 1 — -20 -16 -12 P R I M A R Y F L U I D INCLUS ION E U T E C T I C T E M P E R A T U R E ( ° C ) L A S T M E L T I N G T E M P E R A T U R E FIGURE 3.31: E u t e c t i c and l a s t m e l t i n g temperatures o f i n c l u s i o n s from bladed quartz-carbonate v e i n s from the Wolf prospect. F r e e z i n g data are i n Table 3.12. P or < 3 O 3 CC o 2. -20 — I — -16 — I — -12 6 * & km I l l P R I M A R Y F L U I D I N C L U S I O N E U T E C T I C T E M P E R A T U R E C O L A S T M E L T I N G T E M P E R A T U R E FIGURE 3.32; E u t e c t i c and l a s t m e l t i n g temperatures of i n c l u s i o n s from drusy quartz i n f i l l i n g s from the Wolf p r o s p e c t . F r e e z i n g data are i n Table 3.12. CO 119 TABLE 3.12: Summary of e u t e c t i c and l a s t m e l t i n g temperatures from f l u i d i n c l u s i o n s , Wolf prospect, c e n t r a l B r i t i s h Columbia. Sample l o c a t i o n s are i n F i g u r e s 3.30 and 3.31. Data are presented i n F i g u r e s 3.32 and 3.33. SAMPLE VEIN NUMBER OF EUTECTIC LAST MELTING NUMBER TYPE MEASUREMENTS TEMPERATURE TEMPERATURE °C °C KATR9-1 BLADED 1 -28 -2.0 KA6-6 BLADED 2 -26.5 + 0 -2 . 2 + 0.1 KA188 DRUSY 3 -26.4 + 1.7 -1.3 + 0.2 120 TABLE 3.13: Summary of homogenization temperatures from f l u i d i n c l u s i o n s from d i f f e r e n t v e i n types, Wolf prospect, c e n t r a l B r i t i s h Columbia. Sample l o c a t i o n s are i n F i g u r e s 3.3 0 and 3.31. Data are presented i n F i g u r e s 3.34 t o 3.38. VEIN INCLUSION NUMBER OF AVERAGE TEMPERATURE TYPE TYPE MEASUREMENTS OF HOMOGENIZATION BLADED P 8 229 + 45 °C QUARTZ- PS 5 225 + 65 °C CARBONATE S 7 162 + 36 °C COCKADE P 2 175 + 13 °C QUARTZ PS 1 170°C VEINLETS S 1 179°C DRUSY P 5 253 + 25 °C QUARTZ PS 4 231 + 43 °C S 4 242 + 8 °C BRECCIA P 1 . 250°C INFILLING PS 1 285°C BY QUARTZ S 1 100°C MASSIVE REPLACEMENT PS 2 145 ± 0 °C 121 r a t e s of about 10°C/minute were used t o w i t h i n 30°C of homogenization a t which time r a t e s were decreased t o 2°C/minute. Homogenization data are p l o t t e d , u s i n g a c l a s s i n t e r v a l of 20°C, f o r each v e i n type ( F i g . 3.33) and f o r each o r i g i n type ( F i g . 3.34). Primary, pseudosecondary and secondary f l u i d i n c l u s i o n s from a l l v e i n types are b i m o d a l l y d i s t r i b u t e d with peaks a t 260°C and 180°C ( F i g . 3.34). I n c l u s i o n s i n early-formed bladed quartz-carbonate v e i n s have b i m o d a l l y d i s t r i b u t e d homogenization temperatures w i t h peaks a t 280°C and 180°C ( F i g . 3.33). Homogenization temperatures from quartz i n f i l l i n g b r e c c i a s are unevenly spread from 100°C t o 289°C ( F i g . 3.33). Cockade t e x t u r e d v e i n s have homogenization temperatures c e n t r e d a t 18 0°C ( F i g . 3.33). Secondary f l u i d i n c l u s i o n s hosted i n drusy quartz i n f i l l i n g s , which formed l a t e i n the p a r a g e n e t i c sequence of hydrothermal events a t Wolf, have unimodally d i s t r i b u t e d homogenization temperatures w i t h a dominant peak at 250°C ( F i g . 3.33). 3.6.1.5 I n t e r p r e t a t i o n F l u i d i n c l u s i o n s from the Wolf p r o p e r t y have low c o n c e n t r a t i o n s of d i s s o l v e d s a l t s as determined from l a s t m e l t i n g temperatures ranging from -2.3°C t o -0.9°C (Table 3.12). E u t e c t i c m e l t i n g i n these i n c l u s i o n s (-24°C up t o -28.1°C) c l o s e l y approximates the metastable e u t e c t i c melt i n the H 20-NaCl system (about -28°C) which suggests t h a t VEIN TYPE FIGURE 3.33: Homogenization temperature vs. v e i n type f o r f l u i d i n c l u s i o n samples from the Wolf p r o s p e c t . Data are i n Table 3.12. to ui o z UJ rr or 8 o o F L U I D I N C L U S I O N ORIGIN T Y P E P R I M A R Y P S E U D O S E C O N D A R Y S E C O N D A R Y H O M O G E N I Z A T I O N T E M P E R A T U R E (°C) FIGURE 3.34: Homogenization temperature vs. o r i g i n type f o r f l u i d i n c l u s i o n samples from the Wolf p r o s p e c t . Data are i n Table 3.12. to s a l i n i t y can be l a r g e l y a t t r i b u t e d t o NaCl (Roedder, 1984). L a s t m e l t i n g temperatures correspond t o d i s s o l v e d s a l t c ontents o f between 4.9 and 1.5 weight p e r c e n t NaCl e q u i v a l e n t . Most epithermal d e p o s i t s have s a l i n i t i e s o f between 0.1 and 3.6 weight percent NaCl e q u i v a l e n t (Spooner, 1981). Thus s a l i n i t i e s o f f l u i d i n c l u s i o n s a t Wolf are w i t h i n expected l i m i t s f o r epithermal d e p o s i t s , and re p r e s e n t samples of the l a r g e amounts of h y d r o t h e r m a l l y d r i v e n , low s a l t content waters t h a t passed through these r o c k s . Less than 0.1 mol percent C0 2 i s prese n t i n f l u i d i n c l u s i o n s from the Wolf p r o p e r t y . Such low p a r t i a l p r e s s u r e s o f C0 2 are t y p i c a l f o r epithermal d e p o s i t s ( f i g u r e 5.14 i n Bodnar, 1985). Homogenization temperatures ( a l l t o the l i q u i d phase), r e p r e s e n t the minimum temperature of t r a p p i n g of the f l u i d s a t the time of formation of the host q u a r t z . On the b a s i s of c h a r a c t e r i s t i c e pithermal t e x t u r e s ( s e c t i o n 3.5.2), the Wolf system formed a t shallow depths. Pressure c o r r e c t i o n t o measured temperatures are t h e r e f o r e n e g l i g i b l e , and temperature of homogenization i s approximately equal t o the temperature of t r a p p i n g . F l u i d i n c l u s i o n homogenization temperatures a t Wolf range from a maximum of 289°C t o a minimum of 100°C and show a bimodal d i s t r i b u t i o n ( F i g . 3.34). A n a l y s i s o f each v e i n type and r e s p e c t i v e f l u i d i n c l u s i o n o r i g i n type f o l l o w s . Of the estimated e i g h t hydrothermal events a t Wolf (Table 3.6), f o u r episodes of v e i n i n g are documented u s i n g f l u i d i n c l u s i o n data. These episodes, from o l d e s t t o youngest, are: (1) formation of bladed quartz-carbonate v e i n s , (2) rimming of b r e c c i a fragments by qua r t z , (3) formation of cockade t e x t u r e d v e i n l e t s , and (4) i n f i l l i n g of c a v i t i e s by drusy q u a r t z . Gold and s i l v e r m i n e r a l i z a t i o n i s a s s o c i a t e d w i t h formation of bladed quartz-carbonate v e i n s and rimming of b r e c c i a fragments by quartz ( s e c t i o n 3.5.3). Early-formed bladed quartz-carbonate v e i n s show a bimodal d i s t r i b u t i o n of homogenization temperatures i n primary f l u i d i n c l u s i o n s w i t h peaks a t 270°C and 180°C ( F i g . 3.33). Quartz rimming b r e c c i a fragments shows no d i s t i n c t d i s t r i b u t i o n of homogenization temperatures. Formation of cockade t e x t u r e d v e i n l e t s seems t o have o c c u r r e d a t temperatures c l o s e t o 170°C. Drusy quartz i s unimodally d i s t r i b u t e d w i t h primary f l u i d i n c l u s i o n peaks a t 250°C. These modal temperatures are c o n s i s t e n t w i t h c h a r a c t e r i s t i c temperatures f o r epithermal d e p o s i t s of between 14 0°C and 300°C (Roedder, 1984). Evidence f o r b o i l i n g a t Wolf i s i m p l i e d by t h r e e separate l i n e s of evidence. M a c r o s c o p i c a l l y , b r e c c i a t e x t u r e s w i t h i n v e i n s a s s o c i a t e d w i t h p r e c i o u s metals i n d i c a t e t h a t b o i l i n g might have o c c u r r e d d u r i n g m i n e r a l i z a t i o n . M i c r o s c o p i c a l l y , primary f l u i d i n c l u s i o n s w i t h s i m i l a r homogenization temperatures ( F i g . 3.35) have w i d e l y v a r y i n g l i q u i d t o vapour ( V l i q u i d / ( V l i q u i d + V v a p o u r ) ) o o UJ or or UJ Q_ 2 UJ z o Si N z UJ CD O o I 5 0 0 -3 0 0 -100-PRIMARY FLUID INCLUSIONS ONLY 10 15 — r -20 30 40 VOLUME % VAPOUR ( Vz/( VL+Vv)) FIGURE 3.35: Homogenization temperature v s . l i q u i d t o vapour r a t i o s of primary f l u i d i n c l u s i o n s from the Wolf prospect. Data are i n Table 3.12. to r a t i o s _ _ ( F i g . 3.36), which i s g e n e r a l l y i n d i c a t i v e of b o i l i n g . The most compelling evidence comes from sample KA4-8 (Table 3.11) where growth zones i n quartz are d e f i n e d by two phase l i q u i d and v a p o u r - r i c h i n c l u s i o n s . E p i thermal d e p o s i t s commonly are c h a r a c t e r i z e d by b o i l i n g (Roedder, 1984). At l e a s t two d i f f e r e n t f l u i d s were r e s p o n s i b l e f o r p r e c i p i t a t i o n of v e i n s a t Wolf. F l u i d s c h a r a c t e r i s t i c of e a r l y formed bladed quartz-carbonate v e i n s are more s a l i n e and d e p o s i t e d over a wider temperature range than those of l a t e drusy quartz ( F i g 3.37). The r e s p e c t i v e modal temperatures and s a l i n i t i e s f o r each v e i n type might r e f l e c t m i n e r a l i z i n g events r e l a t e d t o p e r i o d s of peak f l u i d flow. The f i r s t event, probably r e l a t e d t o g o l d and s i l v e r m i n e r a l i z a t i o n , began a t temperatures of 270°C and 180°C, and formed low s u l p h i d e , p r e c i o u s m e t a l - r i c h , bladed quartz-carbonate v e i n s from r e l a t i v e l y s a l i n e f l u i d s . With c o o l i n g , quartz might have rimmed b r e c c i a t e d fragments, and a t 170°C, p r e c i p i t a t e d cockade t e x t u r e d v e i n l e t s . S i n c e temperatures near 250°C seem most f a v o u r a b l e f o r g o l d d e p o s i t i o n i n an e p i t h e r m a l environment (Cathles, o r a l comm., 1986), the lower temperature v e i n quartz understandably i s not known t o be a s s o c i a t e d w i t h p r e c i o u s metals. The formation of drusy quartz from r e l a t i v e l y low s a l i n i t y f l u i d s w i t h i n a c o n f i n e d temperature range of 250°C t o 300°C r e p r e s e n t s a second event a p p a r e n t l y u n r e l a t e d t o s i g n i f i c a n t m i n e r a l i z a t i o n a t 18 16-14 -CO LJ o z Ul or or o o o u . o 6 z 12-io-4" 2" TO 'Si; 8* fa fm • ALL FLUID INCLUSIONS PRIMARY FLUID INCLUSIONS ONLY 15 20 30 40 50 VOLUME % VAPOUR (v£/(VX + Vv)) FIGURE 3.36: Frequency d i s t r i b u t i o n of volume p e r c e n t vapour i n f l u i d i n c l u s i o n s from v e i n s , Wolf p r o s p e c t , showing the wide v a r i a t i o n i n L:V r a t i o s . Data are i n Table 3.12. H t v ) 0 0 HOMOGENIZATION TEMPERATURE (°C) FIGURE 3.37: Homogenization temperature v s . s a l i n i t y f o r f l u i d i n c l u s i o n s from the Wolf p r o s p e c t . Two f l u i d p o p u l a t i o n s (bars represent standard e r r o r o f the means) are observed: (a) f l u i d s c h a r a c t e r i s t i c of e a r l y formed bladed quartz-carbonate v e i n s which have high e r homogenization temperatures and s a l i n i t i e s , and (b) f l u i d s c h a r a c t e r i s t i c o f l a t e drusy quartz which £ have lower homogenization temperatures and s a l i n i t i e s . vo 130 Wolf s i n c e i t c o n t a i n s no g o l d o r s i l v e r v a l u e s ( s e c t i o n 3.5) . C a l c u l a t i o n of depths of emplacement f o r q u a r t z -carbonate v e i n s a t Wolf are p o s s i b l e assuming the f l u i d s were b o i l i n g (Haas, 1971) and u s i n g experimental homogenization temperatures o f 270°C and 180°C. F l u i d s t h a t formed e a r l y quartz-carbonate v e i n s had d e n s i t i e s o f about 0.80 g/cm 3 and 0.91 g/cm 3. C a l c u l a t e d vapour p r e s s u r e s f o r quartz-carbonate v e i n s are about 9.8 and 53.9 bars r e s p e c t i v e l y . C a l c u l a t e d vapour p r e s s u r e s r e p r e s e n t c o n f i n i n g p r e s s u r e s on f l u i d s t h a t are b o i l i n g d u r i n g d e p o s i t i o n . In most n a t u r a l s i t u a t i o n s , c o n f i n i n g p r e s s u r e s are between h y d r o s t a t i c and l i t h o s t a t i c l i m i t s (Roedder, 1984). Under extreme h y d r o s t a t i c c o n d i t i o n s ( F i g . 3.38A), maximum depths of emplacement are approximately 100 m and 625 m f o r low and h i g h temperature quartz-carbonate v e i n s , r e s p e c t i v e l y . Under extreme l i t h o s t a t i c c o n d i t i o n s ( F i g . 3.38B), u s i n g a mean rock d e n s i t y of 2.7 g/cm , the maximum depths of emplacement f o r low and h i g h temperature quartz-carbonate v e i n s are approximately 200 m and 4 0 m. These c a l c u l a t e d depths are c o n s i s t e n t with the epithermal c h a r a c t e r o f the v e i n s ( s e c t i o n 3.5) and are l e s s than one k i l o m e t r e which i s t y p i c a l f o r epithermal d e p o s i t s . The bimodal c h a r a c t e r of quartz-carbonate homogenization temperatures can be e x p l a i n e d by c o n s i d e r i n g a system t h a t a l t e r n a t e s from a c o n d i t i o n i n t e r m e d i a t e GROUND SURFACE GROUND SURFACE GROUND SURFACE A: HYDROSTATIC B : LITHOSTATIC C: INTERMEDIATE CONDITIONS CONDITIONS CONDITIONS (open to surface) (virtually closed (partially open to surface) to surface) FIGURE 3.38: Sketches i l l u s t r a t i n g p o s s i b l e h y d r o s t a t i c , l i t h o s t a t i c o r intermediate c o n d i t i o n s o f v e i n p r e c i p i t a t i o n a t the Wolf p r o s p e c t . Shaded area represents subsequently f i l l e d v e i n opening. U ) between h y d r o s t a t i c and l i t h o s t a t i c ( F i g . 3.38C), t o a c o n d i t i o n t h a t i s e s s e n t i a l l y h y d r o s t a t i c ( F i g . 3.39A). Using a mean rock d e n s i t y of 0.8 g/cm 3, the depth of emplacement f o r low and h i g h temperature quartz-carbonate v e i n s are 18 m and 97 m r e s p e c t i v e l y . The c a l c u l a t e d depth of about 100 m f o r h i g h temperature quartz-carbonate v e i n s p r e c i p i t a t e d under i n t e r m e d i a t e c o n d i t i o n s ( F i g . 3.38C) i s c o i n c i d e n t w i t h t h a t c a l c u l a t e d f o r low temperature q u a r t z -carbonate v e i n s p r e c i p i t a t e d under h y d r o s t a t i c c o n d i t i o n s . T h i s suggests t h a t quartz-carbonate v e i n s were p r e c i p i t a t e d from h i g h and low p r e s s u r e e q u i v a l e n t s of the same hydrothermal f l u i d . Moreover, bladed quartz-carbonate y t e x t u r e s seems t o r e f l e c t a l t e r n a t i n g h y d r o s t a t i c and l i t h o s t a t i c p r e s s u r e s a t the b o i l i n g p o i n t . Formation of a s i l i c a cap s e a l i n g f l u i d movement a t Wolf would cause an i n c r e a s e i n f l u i d p r e s s u r e approaching l i t h o s t a t i c c o n d i t i o n s . M i n e r a l s d e p o s i t e d i n p a r t i a l l y s e a l e d p e r i o d s r e f l e c t h i g h e r pressure c o n d i t i o n s and h i g h e r temperatures of emplacement. Release of p r e s s u r e , by b r e a k i n g a s i l i c a cap, c o u l d induce p r o d u c t i o n of abundant vapour. Subsequent l o s s of v o l a t i l e s and decrease i n f l u i d temperature i n i t i a t e d r a p i d p r e c i p i t a t i o n of m i n e r a l s , i n c l u d i n g g o l d . 3.6.2 STABLE ISOTOPE STUDY The s t a b l e i s o t o p e study of 12 samples was done under the s u p e r v i s i o n of T.K. Kyser a t the U n i v e r s i t y of Saskatchewan, Saskatoon. The o b j e c t i v e s of the study were 133 t o : (1). c a l c u l a t e the oxygen and hydrogen i s o t o p i c compositions of hydrothermal f l u i d s which formed the d e p o s i t , (2) determine the source of hydrothermal f l u i d s , (3) estimate the water t o rock r a t i o i n the f o s s i l hydrothermal system, and (4) c o n s t r a i n the f l u i d e v o l u t i o n of the system with time. Hydrogen i s o t o p e compositions were measured d i r e c t l y from waters e x t r a c t e d from f l u i d i n c l u s i o n s i n quartz v e i n samples. Separate p a r a g e n e t i c v e i n stages ( s e c t i o n 3.5) were hand p i c k e d . F l u i d i n c l u s i o n s from each stage were s t u d i e d i n d e t a i l ( s e c t i o n 3.6.1) and assumed t o r e p r e s e n t s i n g l e p o p u l a t i o n s . The d i r e c t approach f o r measuring oxygen i s o t o p e compositions was not taken because water p r e s e n t i n f l u i d i n c l u s i o n s of oxygen-bearing m i n e r a l s undergoes exchange wit h the host m i n e r a l d u r i n g c o o l i n g , thus changing the 1 8 0 / 1 6 Q r a t i 0 o f t h e f l u i d ( Rye and O ' N e i l , 1968). T h e r e f o r e , oxygen i s o t o p e compositions of the m i n e r a l i z i n g f l u i d s a t Wolf were measured i n d i r e c t l y by i s o t o p i c a n a l y s i s of m i n e r a l assemblages, c a l c u l a t i o n of temperatures of formation u s i n g f l u i d i n c l u s i o n s and p u b l i s h e d experimental data (Carmichael e t a l . , 1974), and a p p l i c a t i o n of e x p e r i m e n t a l l y d e r i v e d f r a c t i o n a t i o n f a c t o r s . 3.6.2.1 Sample p r e p a r a t i o n and a n a l y s i s Twenty analyses of 12 samples from Wolf were used, i n c l u d i n g seven quartz v e i n sample, f i v e whole rock samples and f i v e m i n e r a l separates (Table 3.14; F i g . 3.39). M i n e r a l s e p a r a t i o n f o r quartz was achieved by coarse c r u s h i n g i n an agate mortar f o l l o w e d by h e a t i n g the sample i n s t r o n g HC1. Whole rock samples were p u l v e r i z e d t o l e s s than 200 mesh s i z e i n a tungsten c a r b i d e r i n g m i l l . M i n e r a l s e p a r a t e s , hand-picked from a -3 0 t o +60 mesh s i z e under a b i n o c u l a r microscope, were washed u l t r a s o n i c a l l y i n d i s t i l l e d water. Quartz v e i n samples and m i n e r a l separates were analysed by XRD t o c o n f i r m p u r i t y of sample powders p r i o r t o i s o t o p i c a n a l y s i s . Compositions of whole rock samples were determined by XRF. D i r e c t a n a l y s i s of hydrogen i s o t o p e compositions by e x t r a c t i o n of f l u i d i n c l u s i o n waters used 1 g of c l e a n q u a r t z . I n d i r e c t analyses of oxygen i s o t o p e compositions by a n a l y s i s of m i n e r a l or rock powders used from 5 mg t o 18 mg of sample. V a r i a t i o n s i n the i s o t o p i c r a t i o s of hydrogen and oxygen were measured by mass-spectrometer on H 2 and C0 2 gases, r e s p e c t i v e l y , t h a t were e x t r a c t e d q u a n t i t a t i v e l y from f l u i d i n c l u s i o n s i n crushed m i n e r a l s . Hydrogen was e x t r a c t e d from f l u i d i n c l u s i o n s i n quartz u s i n g the U-technique d e s c r i b e d by B i g e l e i s e n e t a l . (1952) as m o d i f i e d by Kyser and O'Niel (1984). Oxygen was e x t r a c t e d by the BrFjj technique (Clayton and Mayeda, 1963). A l l s t a b l e -i s o t o p e a nalyses were made u s i n g c o n v e n t i o n a l i s o t o p e r a t i o mass spectrometry and are r e p o r t e d u s i n g the d n o t a t i o n i n 135 TABLE 3.14: Oxygen i s o t o p e c o m p o s i t i o n s 1 from samples of whole rock, quartz v e i n and phenocrysts, Wolf prospect, c e n t r a l B r i t i s h Columbia. Sample l o c a t i o n s are i n F i g u r e s 3.40. Data are p l o t t e d i n F i g u r e s 3.42 and 3.43. SAMPLE SAMPLE DESCRIPTION d 1 8 0 NUMBER VEIN SAMPLES KA 022 QUARTZ VEIN - RIDGE ZONE -1.5 Massive replacement o f c r y s t a l t u f f by f i n e s i l i c a w i t h o n l y r e l i c t shadows of former m i n e r a l s remaining. KA 111 QUARTZ VEIN - CHOPPER PAD ZONE 1.6 Grey-white banded c h a l c e d o n i c q u a r t z , hosted by r h y o l i t e . KA 188 QUARTZ VEIN - EAST ZONE -6.7 S i l i c i f i e d t e x t u r e s w i t h i n r h y o l i t e porphyry i n c l u d e : comb quartz v e i n l e t s , drusy c a v i t i e s l i n e d by quartz c r y s t a l s and quartz v e i n l e t s c r o s s c u t t i n g fragments o f r h y o l i t e porphyry. KADDH3-4 QUARTZ VEIN - RIDGE ZONE -4.3 C l e a r f i n e - g r a i n e d quartz rims b r e c c i a fragments i n r h y o l i t e . KADDH4-8 QUARTZ VEIN - POND ZONE -0.1 R h y o l i t e porphyry shows the f o l l o w i n g t e x t u r e s : bladed quartz-carbonate, rimming of ho s t rock fragments by quartz, open space f i l l i n g by m i l k y q u a r t z , and drusy c a v i t i e s l i n e d by q u a r t z . KADDH6-2 QUARTZ VEIN - POND ZONE S i l i c i f i e d t e x t u r e s i n r h y o l i t e porphyry i n c l u d e : comb quar t z , quartz i n f i l l i n g , c h a l c e d o n i c .banding and rimming of v e i n w a l l s and drusy c a v i t i e s l i n e d by quartz c r y s t a l s . 1.4 KATR9-1 QUARTZ VEIN - TRENCH 9, RIDGE ZONE Densely bladed quartz v e i n sample (blades up t o 2 cm long) w i t h i n r h y o l i t e . 0.8 136 TABLE 3.14: (continued) SAMPLE SAMPLE DESCRIPTION d 1 8 0 NUMBER WHOLE ROCK SAMPLES KA 078 WHOLE ROCK - K-FELDSPAR QUARTZ PORPHYRY -1.6 The rock c o n t a i n s 5% quartz phenocrysts (1mm i n diameter) and 5% o r t h o c l a s e phenocrysts ( l e s s than 2 mm i n diameter) suspended i n a c r y p t o c r y s t a l l i n e groundmass. No hydrothermal a l t e r a t i o n i s e v i d e n t . KA 112 WHOLE ROCK - RHYOLITE 0.2 The rock c o n t a i n s 10% euhedral o r t h o c l a s e phenocrysts (1 t o 2 mm i n diameter) and 5% i r r e g u l a r quartz c r y s t a l s (1 mm i n diameter), s e t i n a f i n e - g r a i n e d groundmass. S p h e r u l i t i c t e x t u r e s and flow banding are common. F i e l d r e l a t i o n s suggest t h a t the r h y o l i t e c o u l d have been emplaced as a dome. KA 128 WHOLE ROCK - RHYOLITE PORPHYRY -1.0 Sample c o n t a i n s 50% euhedral o r t h o c l a s e c r y s t a l s (1 cm i n diameter) and 10% quartz c r y s t a l s (2 t o 3 mm i n diameter) s e t i n a f i n e groundmass. F i e l d r e l a t i o n s i n d i c a t e t h a t t h i s u n i t i s i n t r u s i v e . KA 135 WHOLE ROCK - CRYSTAL TUFF 1.6 'Crowded' rock w i t h 30% euhedral o r t h o c l a s e phenocrysts (1 t o 3 mm i n diameter) and 10% i r r e g u l a r quartz phenocrysts (1 mm i n diame t e r ) . Many of the c r y s t a l s are broken. KA 178 WHOLE ROCK - PORPHYRITIC ANDESITE -3.6 Sample c o n t a i n s 10% p l a g i o c l a s e , 10% hornblende, and 20% pyroxene phenocrysts s e t i n a c r y p t o c r y s t a l l i n e groundmass. MINERAL SEPARATES FROM UNITS DESCRIBED ABOVE KA 078 QUARTZ PHENOCRYST SEPARATE 6.0 KA 078 FELDSPAR PHENOCRYST SEPARATE -7.4 KA 112 QUARTZ PHENOCRYST SEPARATE 8.1 KA 135 QUARTZ PHENOCRYST SEPARATE 6.6 KA 135 FELDSPAR PHENOCRYST SEPARATE 0.5 1. A l l s t a b l e i s o t o p e analyses were done i n the l a b o r a t o r y of T.K. Kyser, 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 Saskatchewan. 137 WEST HALF FIGURE 3.39: L o c a t i o n s of samples of whole rock, v e i n and m i n e r a l separate samples used f o r oxygen i s o t o p e analyses from the Wolf p r o p e r t y . A)west h a l f , and B) e a s t h a l f . 138 FIGURE 3.39: L o c a t i o n s of samples of whole rock, v e i n and m i n e r a l s e p a r a t e samples used f o r oxygen i s o t o p e analyses from the Wolf p r o p e r t y . A)west h a l f , and B) e a s t h a l f . 139 u n i t s o f per m i l ( ° / 0 0 ) r e l a t i v e t o SMOW standard (Standard Mean Ocean Water). 3.6.2.2 E r r o r analyses R e p l i c a t e analyses of v e i n , whole rock and m i n e r a l separate samples are r e p r o d u c i b l e w i t h a p r e c i s i o n o f + 0.2 per m i l (2d) f o r d 1 8 0 (Table 3.15) and + 5 per m i l (2d) f o r dD (Kyser, p e r s . comm., 1987). The d 1 8 0 v a l u e o f the NBS-28 quartz standard i s 9.6 (Kyser, p e r s . comm., 1987). Standard samples are r e p r o d u c i b l e with an accuracy of + 0.1 per m i l (Table 3.17). 3.6.2.3 I s o t o p i c composition of hydrothermal f l u i d s The hydrogen i s o t o p i c compositions of f l u i d s i n e q u i l i b r i u m w i t h t h r e e quartz v e i n s were d i r e c t l y measured by e x t r a c t i n g waters from primary f l u i d i n c l u s i o n s r e p r e s e n t i n g a s i n g l e p o p u l a t i o n . Values range from -161 per m i l t o -176 per m i l (Table 3.16). Oxygen i s o t o p e compositions were c a l c u l a t e d i n d i r e c t l y by i s o t o p i c a n a l y s i s of m i n e r a l assemblages. Assumptions, techniques and r e s u l t s are below. At e q u i l i b r i u m , i s o t o p i c s p e c i e s p a r t i t i o n ( f r a c t i o n a t e ) among a v a i l a b l e s i t e s i n c o e x i s t i n g m i n e r a l s and f l u i d through mass-dependent d i f f e r e n c e s i n chemical and p h y s i c a l behaviour. The p a r t i t i o n i n g o f two i s o t o p e s between two s p e c i e s , X and Y> i s d e s c r i b e d by the f r a c t i o n a t i o n f a c t o r , a = R v/R v (where R i s the i s o t o p e 140 TABLE 3.15: D u p l i c a t e data and U n i v e r s i t y o f Saskatchwan standard samples used t o determine p r e c i s i o n and accuracy o f oxygen i s o t o p e a n a l y s e s 1 a t the Wolf prospect, c e n t r a l B r i t i s h Columbia. SAMPLE NO. DUPLICATE 1 DUPLICATE 2 STANDARD ( ° / 0 0 ) (°/ 0 0> < ° / 0 0 ) KADDH6-2 1.4 1.6 QUARTZ VEIN KA135 6.6 6.6 QUARTZ MINERAL SEPARATE AGS 2 , 9.5 QUARTZ SAND 1. A l l s t a b l e i s o t o p e analyses were done i n the l a b o r a t o r y of T.K Kyser, Department of 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 Saskatchewan. 2. The v a l u e o f the AGS standard i s d 1 8 0 =9.6 ° / 0 0 . TABLE 3.16: C a l c u l a t e d oxygen i s o t o p e compositions ( s e c t i o n 3.6.2) and measured hydrogen i s o t o p e c o m p o s i t i o n s 1 of hydrothermal f l u i d s a t the Wolf prospect, c e n t r a l B r i t i s h Columbia. SAMPLE SAMPLE d 1 8 0 TEMPERATURE d 1 8 0 dD NUMBER MATERIAL MATERIAL °C WATER WATER KA022 VEIN QUARTZ -1.5 145 -17.9 -176 KA111 VEIN QUARTZ 1.6 <170 -12.7 KA188 VEIN QUARTZ -6.7 240 -16.6 -161 KA3-4 VEIN QUARTZ -4.3 267 -12.9 KA4-8 VEIN QUARTZ -0.1 183 -13.5 KA6-2 VEIN QUARTZ 1.4 170 -12.9 KATR9-1 VEIN QUARTZ 0.8 279 -7.4 -163 KA078 WHOLE ROCK -1.6 250 -7.9 KA112 WHOLE ROCK 0.2 250 -6.1 KA128 WHOLE ROCK -1.0 250 -7.3 KA135 WHOLE ROCK 1.6 250 -4.7 KA178 WHOLE ROCK -3,.6 250 -9.9 KA078 FELDSPAR SEPARATE -7.4 250 -11.5 KA135 FELDSPAR SEPARATE 0.5 250 -3.6 1. A l l s t a b l e i s o t o p e analyses were done i n the l a b o r a t o r y of T.K. Kyser, 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 Saskatchewan. 142 r a t i o ; — f o r example D/H or 1 8 0 / 1 6 0 ) . The degree of f r a c t i o n a t i o n , independent of p r e s s u r e because o f the n e a r l y i d e n t i c a l volume of heavy and l i g h t i s o t o p e s (Sheppard, 1977), but v a r i e s i n v e r s e l y with temperature i n a p r e d i c t a b l e way (Urey, 1947; B i g e l e i s e n and Mayer, 1947). Thus, the i s o t o p i c composition can be i n d i r e c t l y c a l c u l a t e d g i v e n : (1) a n a l y t i c a l i s o t o p e data from a m i n e r a l t h a t was i n e q u i l i b r i u m with the hydrothermal f l u i d , (2) the f r a c t i o n a t i o n c o e f f i c i e n t (a) between t h a t m i n e r a l and water, and (3) an independent estimate o f temperature o f formation o f the mi n e r a l through f l u i d i n c l u s i o n s o r oth e r geothermometers. The oxygen i s o t o p e compositions of hydrothermal f l u i d s i n e q u i l i b r i u m with quartz v e i n s a t Wolf were c a l c u l a t e d u s i n g : (1) the a n a l y t i c a l i s o t o p e data from the v e i n s (Table 3.16), (2) the experimental quartz-water f r a c t i o n a t i o n curves o f C l a y t o n e t a l . (1972), and (3) averaged homogenization temperature from primary f l u i d i n c l u s i o n data ( s e c t i o n 3.6.1). Equation 3.1. QUARTZ-WATER (Clayton e t a l , 1972): 1 0 0 0 l n a ( q u a r t z _ w a t e r ) = 3.38(10 6/T 2) - 2.90 where T = temperature (K), and the temperature range = 2 00 to 500°C. R e s u l t s o f these c a l c u l a t i o n s (Table 3.16) show a wide spread o f i s o t o p i c compositon i n the d e p o s i t i o n a l f l u i d s of between d 1 8 0 = -7.4 and -17.9 ° / 0 0 . The oxygen i s o t o p e composition of d e p o s i t i o n a l f l u i d s was a l s o c a l c u l a t e d u s i n g the assumption of T a y l o r (1979) t h a t the measured d 1 8 0 whole rock v a l u e i s equal t o the d 1 8 0 v a l u e of p l a g i o c l a s e ( A n 3 0 ) . C a l c u l a t i o n s were made u s i n g : (1) the whole rock a n a l y t i c a l i s o t o p e data (Table 3.16), (2) the p l a g i o c l a s e ( A n 3 0 ) - w a t e r curves o f O'Neil and T a y l o r (1967), and (3) an estimated temperature o f formation of the rock of 800°C (from F i g . 6-12 i n Carmichael e t a l . , 1974). Equation 3.2. PLAGIOCLASE(An 3 0)-WATER (O'Neil and T a y l o r , 1967): 1 0 0 0 1 n a ( p l a g > _ w a t e r ) = 2.68(10 6/T 2)-3.53 where T = temperature (K), and the temperature range = any g e o l o g i c a l l y reasonable temperature R e s u l t s o f these c a l c u l a t i o n s (Table 3.16) show a spread of i s o t o p i c composition i n the d e p o s i t i o n a l f l u i d s of between d l s O = -2.4 and +2.8 ° / 0 0 . These v a l u e s are h i g h e r than those c a l c u l a t e d from quartz v e i n s . 3.6.2.4 Water t o Rock r a t i o The water t o rock r a t i o o f the f o s s i l hydrothermal system a t Wolf can be estimated assuming i s o t o p i c e q u i l i b r i u m between w a l l r o c k and f l u i d s (Ohmoto and Rye, 1974). U n a l t e r e d r h y o l i t e rocks t y p i c a l l y have a d 1 8 0 va l u e of about V ° / 0 0 ( F i e l d and F i f a r e k , 1985). R h y o l i t i c rocks from Wolf t h a t have been exposed t o hydrothermal f l u i d s have v a l u e s lower than t h i s norm (Table 3.16). The water t o rock r a t i o i s dependent on temperature, the d x 0 v a l u e o f 144 the hydrothermal f l u i d , and the d i f f e r e n c e between a l t e r e d and u n a l t e r e d v a l u e s . • i ft C a l c u l a t i o n of the o r i g i n a l 0 content of the hydrothermal f l u i d s a t Wolf from d 1 8 0 v a l u e s f o r quartz v e i n s gave v a l u e s ranging from -7.4 t o -17.9 ° / 0 0 . These v a l u e s r e p r e s e n t the e q u i l i b r a t i o n of hydrothermal f l u i d s w i t h w a l l r o c k of c o n s i d e r a b l y h i g h e r 1 8 0 content. Thus, the o r i g i n a l i s o t o p i c composition of the f l u i d s must have been l e s s than d 1 8 0 = -17.9 ° / 0 0 . The i n i t i a l d 1 8 0 of meteoric waters p r i o r t o exchange with w a l l r o c k i s b e s t c a l c u l a t e d u s i n g D/H analyses of f l u i d i n c l u s i o n s and equation 3.3. E q u a t i o n 3 . 3 . INITIAL METEORIC WATER ( C r a i g , 1961): dD = 8 d 1 8 0 + 1 0 The average dD v a l u e as measured from f l u i d i n c l u s i o n waters i s -166 ° / 0 0 (Table 3.16). The dD v a l u e f o r meteoric water i n the Wolf area today i s approximately - 1 6 0 ° / o o ( f i g u r e 6.3 i n T a y l o r , 1979). T h i s meteoric i s o t o p e composition r e f l e c t s l a t i t u d e and e l e v a t i o n . Since hydrogen i s o t o p i c compositions of meteoric waters have undergone on l y a 1 t o 2% s h i f t toward h e a v i e r v a l u e s s i n c e T e r t i a r y time ( T a y l o r , 1974; O'Neil and Silberman, 1974), the -166 ° / 0 0 v a l u e determined e x p e r i m e n t a l l y from f l u i d i n c l u s i o n s a t Wolf i s reasonable. By u s i n g the dD v a l u e of -166 °/00, the i n i t i a l d 1 8 0 of waters a t Wolf i s c a l c u l a t e d as -22 ° / 0 0 from equation 3. Assuming continuous r e c i r c u l a t i o n and r e - e q u i l i b r a t i o n of hydrothermal f l u i d s i n a c l o s e d system, the water t o rock r a t i o a t Wolf i s c a l c u l a t e d u s i n g the r e l a t i o n s h i p s i n equa t i o n 3.4. Equation 3.4. CLOSED SYSTEM W/R (Ohmoto and Rye, 1974; T a y l o r , 1979): w/r = d—rock - d—rock d-'-water - ( d f r o c k - A ) where: A = d rock - d^water, l = i n i t i a l v a l u e and f = f i n a l v a l u e a f t e r exchange. R e s u l t s o f these c a l c u l a t i o n s (Table 3.17) i n d i c a t e water t o rock r a t i o s o f 0.21 t o 0.46 a t Wolf. C a l c u l a t e d water t o rock r a t i o s do not account f o r b o i l i n g and mixing of unexchanged meteoric water ( F i e l d and F i f a r e k , 1985). Assuming hydrothermal f l u i d s make o n l y one pass through an open system, the water t o rock r a t i o s a t Wolf are 0.19 t o 0.42 (Table 3.17) as c a l c u l a t e d from equation 5. Equation 3.5. OPEN SYSTEM W/R (T a y l o r , 1979): w/r = In |~ d—water + - d—rock .dH/ater - ( d f r o c k - A ) f -f . . . . where: A = d rock - d water, l = i n i t i a l v a l u e , and f = f i n a l v a l u e a f t e r exchange. Both open and c l o s e d system models g i v e o n l y minimum water t o rock r a t i o s because: (1) a l o t of water may pass through the rocks without e q u i l i b r a t i n g , and (2) the water e n t e r i n g the volume of rock under c o n s i d e r a t i o n c o u l d have become d e p l e t e d i n 1 8 0 from the o r i g i n a l i s o t o p i c composition i t had bef o r e e n t e r i n g the rock system (Sheppard, 1977). 146 TABLE 3.17: C a l c u l a t e d water t o rock r a t i o s ( s e c t i o n 3.5.2) assuming c l o s e d and open systems a t the Wolf prospect, c e n t r a l B r i t i s h Columbia. SAMPLE NUMBER dl80 WHOLE ROCK dl80 WATER W/R CLOSED SYSTEM W/R OPEN SYSTEM KA078 -1.6 -7.9 0.61 0.48 KA112 0.2 -6.1 0.43 0.36 KA128 -1.0 -7.3 0.54 0.43 KA135 , 1.6 -4.7 0.31 0.27 KA178 -3.6 -9.9 0.88 0. 63 147 3.6.2.5 Geothermometry M i n e r a l separates of quartz and potassium f e l d s p a r phenocryst p a i r s were analysed t o estimate the temperature of formation of t h e i r host r o c k s . F r a c t i o n a t i o n f a c t o r s (10001na = A) f o r mineral p a i r s have been determined e x p e r i m e n t a l l y (e.g. B l a t t n e r and B i r d , 1974; Sheppard and Schwarcz, 1970), and d e r i v e d e m p i r i c a l l y (e.g. B o t t i n g a and Javoy, 1974; F i e l d and F i f a r e k , 1985) assuming p r e s e r v a t i o n of i s o t o p i c e q u i l i b r i u m between m i n e r a l s . Given the f r a c t i o n a t i o n f a c t o r ( g u a r t z - K - f e l d s p a r ) between these two mi n e r a l s , the temperature of d e p o s i t i o n i s expressed by equa t i o n 3.6: Equat i o n 3.6. QUARTZ-KFELDSPAR (Matsuhisa e t a l . , 1979): T(K) = (0.68(10 3) )  ( A q u a r t z - K f e l d s p a r " ° - 0 2 ) 1 / 2 where T = temperature (K), temperature range = 500 t o 800°C, 18 18 a n d q u a r t z - k f e l d s p a r = d °quartz " d °kfeldspar* At Wolf, quartz phenocrysts have v a l u e s from 6.0 t o 8.1 ° / 0 0 and potassium f e l d s p a r phenocrysts have v a l u e s between -7.4 and +0.5 ° / 0 0 (Table 3.16). Common u n a l t e r e d rock forming m i n e r a l s such as quartz, carbonates and a l k a l i f e l d s p a r s have l a r g e d 1 8 0 v a l u e s of 6 t o 1 3 ° / 0 0 ( F i e l d and F i f a r e k , 1985). Consequently, i t appears t h a t quartz phenocrysts have r e t a i n e d the o r i g i n a l composition o f the magma which formed r h y o l i t e s a t Wolf, whereas K - f e l d s p a r phenocrysts are de p l e t e d i n i O 0 . The temperature o f formation o f r h y o l i t e s a t Wol£, cannot be c a l c u l a t e d u s i n g q u a r t z - f e l d s p a r m i n e r a l p a i r s because f e l d s p a r compositions are d e p l e t e d i n 1 8 0 and r e f l e c t the composition of hydrothermal f l u i d s t h a t passed through the rocks a t Wolf. The oxygen i s o t o p e composition of hydrothermal f l u i d s i n e q u i l i b r i u m with potassium f e l d s p a r phenocrysts are c a l c u l a t e d u s i n g : (1) a n a l y t i c a l i s o t o p e data from the potassium f e l d s p a r phenocrysts (Table 3.16), (2) the experimental f e l d s p a r - w a t e r f r a c t i o n a t i o n curves o f Equation 3.7, and (3) an estimated temperature of formation o f the rock of 800°C (from f i g u r e 6-12 i n Carmichael e t a l . , 1974). Equation 3.7. ALKALI FELDSPAR-WATER (O'Neil and T a y l o r , 1967): lOOOlna ( a l k a l i feldspar-water) = 2.91(10 6/T 2) - 3.41 where T = temperature (K) and temperature range = 350 t o 800°C. R e s u l t s o f these c a l c u l a t i o n s (Table 3.16) show i s o t o p i c compositions i n the d e p o s i t i o n a l f l u i d s o f d 1 8 0 = -6.5 and 1.4 ° / 0 0 . These compositions are s i m i l a r t o those c a l c u l a t e d from whole rock data ( s e c t i o n 3.6.2.3). 3.6.2.6 I n t e r p r e t a t i o n Quartz v e i n s , whole rock samples and a l k a l i f e l d s p a r phenocrysts are d e p l e t e d i n 1 8 0 by 3.9 t o 9.1 ° / 0 0 (Table 3.16), assuming t h a t normal igneous rocks on the e a r t h have minimum d 1 8 0 of +5.5 ° / 0 0 ( T a y l o r , 1968). T h i s d e p l e t i o n i s i n d i c a t i v e o f a l t e r a t i o n o f w a l l rock by l a r g e volumes of 149 low 1 8 © content hydrothermal f l u i d s a t e l e v a t e d temperatures. Thus, the h i g h degree of i s o t o p i c exchange r e f l e c t s complete s a t u r a t i o n of the host rocks w i t h hydrothermal f l u i d s . O r i g i n a l d e p o s i t i o n a l f l u i d s a t Wolf had an i n i t i a l d x o 0 of -22 / 0 0 p r i o r t o exchange with w a l l r o c k . These f l u i d s were e n r i c h e d i n 1 8 0 by almost the same amount as w a l l r o c k was d e p l e t e d i n 1 8 0 . Such r e c i p r o c a l s h i f t s i n i s o t o p i c composition have been r e p o r t e d from modern and f o s s i l geothermal systems hosted i n h i g h l y f a u l t e d , permeable v o l c a n i c rocks a s s o c i a t e d w i t h h i g h - l e v e l igneous i n t r u s i o n s ( T a y l o r , 1979; F i e l d and F i f a r e k , 1985; McDonald, 1987). C a l c u l a t e d oxygen i s o t o p e compositions and e x p e r i m e n t a l l y d e r i v e d hydrogen i s o t o p e compositions f o r quartz v e i n s a t Wolf can o n l y have o r i g i n a t e d from meteoric water wi t h v i r t u a l l y no c o n t r i b u t i o n from magmatic or metamorphic sources. On F i g u r e 3.40, the p o s s i b l e range of d x o O d e p o s i t i o n a l f l u i d composition i s p l o t t e d t o g e t h e r w i t h known dD v a l u e s from t h r e e quartz v e i n s a t Wolf and other e p i t h e r m a l d e p o s i t s . The Wolf p r o p e r t y i s comparable t o o t h e r s i g n i f i c a n t T e r t i a r y v o l c a n i c - h o s t e d e p i t h e r m a l d e p o s i t s i n B.C. and the Yukon T e r r i t o r y (McDonald, 1987; N e s b i t t e t a l . , 1985) as w e l l as t o the B a s i n and Range r e g i o n of the U n i t e d S t a t e s ( T a y l o r , 1979; N e s b i t t e t a l . , 1985, F i e l d and F i f a r e k , 1985). 150 2 0 --20 " -40 --60 -80 --100 --120 • -140 --160 " -180 -200 -25 METAM ORPHIC WATERS PRIMARY MAGMATIC WATERS 0 Bodie, U.S.A. Aurora, U.S.A. Jarbidge, U.SA. Skukum • Comsfock Lode, U.S.A. Blackdome , B.C -20 -15 -10 10 18, 0 (%J 15 20 Mmmm RANGE OF ISOTOPIC COMPOSITION OF FLUID ASSOCIATED WITH T H E WOLF PROSPECT FIGURE 3.40: dD v s . d 1 8 0 v a l u e s showing f i e l d s f o r magmatic and metamorRhic water and the range of d e p o s i t i o n a l f l u i d composition a t Wolf, c e n t r a l B.C. Values f o r other T e r t i a r y v o l c a n i c - h o s t e d e p i t h e r m a l d e p o s i t s i n B.C., Yukon T e r r i t o r y , and western U.S.A. are a l s o shown. C a l c u l a t i o n s of water t o rock r a t i o s a t Wolf f o r c o n d i t i o n s between extremely open or c l o s e d systems show t h a t f o r every gram of rock i n the area of the d e p o s i t , a t l e a s t 0.20 t o 0.54 grams of water moved through the system. These r e p r e s e n t minimum estimates c o n s i d e r i n g t h a t some of the water p a s s i n g through the system might never have touched the w a l l r o c k and t h a t the l a s t phases of f l u i d p r o bably e q u i l i b r a t e d b e f o r e p a s s i n g completely through the v e i n system. The c a l c u l a t e d water t o rock r a t i o s are c o n s i s t a n t with r e p o r t e d r a t i o s of 0.2 t o 2 from e p i t h e r m a l d i s t r i c t s i n the U.S.A. (T a y l o r , 1974). The low s a l i n i t i e s i n f l u i d i n c l u s i o n s ( s e c t i o n 3.6.1) a l s o support a h i g h water t o rock r a t i o t h a t would m a i n t a i n d i l u t i o n of s o l u t i o n s . The abundance of v e i n i n g a t Wolf ( s e c t i o n 3.5) i m p l i e s t h a t m i n e r a l d e p o s i t i o n must have occ u r r e d i n an open system of f r a c t u r e s and f a u l t zones t o a l l o w passage of l a r g e q u a n t i t i e s of f l u i d . Such evidence, combined wi t h c h a r a c t e r i s t i c a l l y low background v a l u e s of g o l d and s i l v e r i n Ootsa Lake Group rocks ( s e c t i o n 3.5), makes incoming hydrothermal f l u i d s a p l a u s i b l e source f o r m i n e r a l i z a t i o n a t Wolf. E v o l u t i o n of hydrothermal f l u i d s a t Wolf can be c h a r t e d u s i n g the t h r e e quartz v e i n analyses t h a t p l o t a l o n g a h o r i z o n t a l l i n e i n F i g u r e 3.41. Sample KATR9-1, c o l l e c t e d from the Ridge Zone, i s from an early-formed q u a r t z -carbonate v e i n a s s o c i a t e d with p r e c i o u s metal 152 FIGURE 3.41: dD v s . d 1 8 0 f o r quartz v e i n samples from the Wolf pr o s p e c t with proposed f l u i d e v o l u t i o n l i n e . m i n e r a l i z a t i o n . Isotopes of oxygen and hydrogen p l o t ( F i g . 3.41) f u r t h e s t from the present day meteoric water l i n e . Sample KA188, c o l l e c t e d from the East Zone, i s of l a t e -formed drusy quartz ( s e c t i o n 3.5); i s o t o p e s p l o t ( F i g . 3.41) c l o s e s t t o the meteoric water l i n e . Large volumes of hydrothermal f l u i d s probably c a r r i e d p r e c i o u s metals i n s o l u t i o n from source rocks d i s t a n t from the p r o p e r t y , d e p o s i t i n g most p r e c i o u s metals i n i t i a l l y when temperatures were hot enough t o cause b o i l i n g which i n t u r n i s r e l a t e d t o e r u p t i o n , b r e c c i a t i o n , and r a p i d c o o l i n g o f the f l u i d , and e v o l v i n g t o l a t e r p r e c i o u s metal poor f l u i d s w i t h the waning of hydrothermal a c t i v i t y . 3.7 CONCLUSIONS 3.7.1 ORIGIN The Wolf epithermal g o l d - s i l v e r p r o s p e c t occurs i n mid-Eocene Ootsa Lake Group v o l c a n i c rocks i n c e n t r a l B r i t i s h Columbia ( F i g . 2.1). The Ootsa Lake Group unconformably o v e r l i e s Lower and Middle J u r a s s i c rocks o f the Haz e l t o n Group and i s preserved as a b l o c k - f a u l t e d e r o s i o n a l remnant i n the Capoose Lake area. Ootsa Lake Group rocks i n c e n t r a l B r i t i s h Columbia r e p r e s e n t widespread v o l c a n i s m of s h o r t d u r a t i o n i n the Eocene (Nelson, 1985). Ootsa Lake Group rocks a t Wolf are grouped i n t o f o u r assemblages ( s e c t i o n 3.2) p o s s i b l y r e l a t e d t o c a l d e r a c o l l a p s e ( F i s h e r and Schmincke, 1984; S i l l i t o e and Bonham, 1984; S i l l i t o e e t a l . , 1984). F i g u r e 3.42 i l l u s t r a t e s 154 WEST EAST .tuff ring Hazelton Group Approx. 5 km — -i T - - 4 - - - -I FIGURE 3.42: Schematic diagram i l l u s t r a t i n g Ootsa Lake Group v o l c a n i c s e t t i n g a t Wolf u s i n g a c a l d e r a c o l l a p s e model. 1 = conglomerate and t u f f s , 2 = p y r o c l a s t i c assemblage, 3 = r h y o l i t e dome, flows and b r e c c i a , and 4 = i n t r u s i o n s . 155 i n t e r p r e t a t i o n of Ootsa Lake Group rocks a t Wolf u s i n g a c a l d e r a c o l l a p s e model (Andrew and Godwin, 1986). However, the i n t e r p r e t a t i o n i s l i m i t e d by the sparce outcrop i n the area. Assemblage one, s t e e p l y d i p p i n g conglomeratic and t u f f a c e o u s u n i t s , c o n t a i n s reworked m a t e r i a l of both v o l c a n i c and p l u t o n i c provenance. These u n i t s might r e f l e c t p r o x i m i t y t o a major r i n g f a u l t t h a t c o u l d d e f i n e the boundary of the c a l d e r a w i t h adjacent Hazelton v o l c a n i c r o c k s . Assemblage two, mainly f l a t - l y i n g p y r o c l a s t i c u n i t s , r e p r e s e n t s magmatic d i f f e r e n t i a t i o n t o f e l s i c , e x p l o s i v e v o l c a n i s m forming a t u f f r i n g and d e p o s i t s w i t h i n a c a l d e r a . Assemblage t h r e e , r h y o l i t e flows and b r e c c i a s , r e p r e s e n t s doming and a s s o c i a t e d hydrothermal products r e l a t e d t o f e l s i c v o l c a n i s m w i t h i n the c a l d e r a . Assemblage f o u r , r e p r e s e n t s f i n a l magmatic resurgence c a u s i n g emplacement of r h y o l i t e porphyry and dykes through the v o l c a n i c p i l e . T h i s i n t r u s i o n was the l a s t event p r i o r t o b l o c k f a u l t i n g and the formation of m i n e r a l i z e d v e i n s . Pearce element r a t i o diagrams are used t o e s t a b l i s h t h a t the Eocene v o l c a n i c rocks a t Wolf are comagmatic and may have formed i n p a r t by f e l d s p a r d i f f e r e n t i a t i o n ( s e c t i o n 3.3.5). A n d e s i t e s , on the western s i d e of the p r o p e r t y ( F i g . 3.1) are not comagmatic wit h the Eocene f e l s i c v o l c a n i c rocks ( F i g s . 3.15 and 3.16). A p e r i o d of e r o s i o n from mid-Eocene t o mid-Miocene time was f o l l o w e d by d e p o s i t i o n of p o o r l y c o n s o l i d a t e d mid-Miocene e p i c l a s t i c rocks with a palynomorph assemblage 156 c o r r e l a t i v e t o the F r a s e r Bend Formation (G. Rouse, pe r s . comm., 1988). Post mid-Miocene low-angle t h r u s t i n g (?) of Ootsa Lake Group rocks over the sedimentary rocks a t Wolf i s s i m i l a r t o t h a t seen by Rouse (pers. comm., 1988) i n the Kenney Dam area. 3.7.2 DEPOSIT MODEL The model proposed f o r the Wolf epithermal g o l d - s i l v e r p r o s p e c t i s d e p i c t e d i n F i g u r e 3.43. G e o l o g i c a l s e t t i n g , v e i n and b r e c c i a t e x t u r e s , a l t e r a t i o n and metal d i s t r i b u t i o n p a t t e r n s a t Wolf resemble those of a low sulphur, hot s p r i n g or s i l i c i f i e d stockwork d e p o s i t (Berger and Eimon, 1983; Silverman and Berger, 1985; Hayba e t a l . , 1985). V e i n emplacement was probably caused by resurgent magmatic a c t i v i t y which produced a r h y o l i t e porphyry stock and c o u l d have i n i t i a t e d hydrothermal c i r c u l a t i o n . Hydrothermal outfl o w was ce n t r e d on a t l e a s t f i v e zones a t Wolf, s e v e r a l of which were accompanied by s i g n i f i c a n t m i n e r a l i z a t i o n ( s e c t i o n 3.5). M i n e r a l i z a t i o n a t Wolf i s hosted i n zones o f s i l i c i f i e d r h y o l i t e and r h y o l i t e porphyry, quartz and r h y o l i t e b r e c c i a s and quartz v e i n stockworks. Block f a u l t i n g p r o v i d e d c o n d u i t s f o r c i r c u l a t i n g hydrothermal f l u i d s and s t r u c t u r a l l y c o n t r o l l e d d e p o s i t i o n of v e i n s . At l e a s t e i g h t d i s t i n c t phases o f repeated, e p i s o d i c and e x p l o s i v e stockwork v e i n i n g a n d , b r e c c i a t i o n are re c o g n i s e d ( s e c t i o n 3.5.2). V e i n t e x t u r e s i n d i c a t e d e p o s i t i o n i n a n e a r - s u r f a c e 157 PALEOSURFACE Ag <AU hydrothermal explosion breccia Tuffaceous material — W A I OOm Ag /Au Jfl.10/ —v/v> I Km Appr ox . 5 Km FIGURE 3.43: Schematic c r o s s - s e c t i o n o f low sulphur, h o t - s p r i n g type s i l i c i f i e d stockwork model "for the g e n e s i s of the Wolf prospect, c e n t r a l B r i t i s h Columbia. 158 environment where l i t h o s t a t i c p r e s s u r e s were low enough t o m a i n t a i n open spaces produced by f a u l t i n g . B r e c c i a t e x t u r e s i n d i c a t e e x p l o s i v e p r e s s u r e r e l e a s e l e a d i n g t o l o c a l rock f r a c t u r e and p r e c i p i t a t i o n of m i n e r a l i z a t i o n . Metal d i s t r i b u t i o n graphs and c o r r e l a t i o n m a t r i c i e s i n d i c a t e o n l y one m i n e r a l i z i n g event on the p r o p e r t y . T h i s event i s a s s o c i a t e d with formation of bladed quartz-carbonate v e i n s and b r e c c i a i n f i l l i n g which host n a t i v e s i l v e r , e l e c t r u m and s i l v e r s u l p h o s a l t s . F l u i d i n c l u s i o n s t u d i e s i n d i c a t e t h a t a t l e a s t two d i f f e r e n t f l u i d s were r e s p o n s i b l e f o r p r e c i p i t a t i o n of v e i n s a t Wolf. Early-formed, m i n e r a l i z e d quartz carbonate v e i n s are c h a r a c t e r i z e d by homogenization temperatures of 170°C and 270°C and s a l i n i t i e s of approximately 4 weight p e r c e n t NaCl. Late cockade t e x t u r e d v e i n l e t s and drusy quartz are c h a r a c t e r i z e d by homogenization temperatures of 250°C and 170°C r e s p e c t i v e l y , and s a l i n i t i e s of approximately 2 weight percent NaCl. These h i g h homogenization temperatures support the presence of an igneous body a t depth which s u p p l i e d thermal energy t o d r i v e the hydrothermal c i r c u l a t i o n . Both f l u i d s , c h a r a c t e r i z e d by l e s s than 0.1 mol percent C0 2, are t y p i c a l of epithermal d e p o s i t s . Compelling evidence f o r b o i l i n g a t Wolf i s the d e f i n i t i o n of growth zones i n quartz by two phase l i q u i d and v a p o u r - r i c h i n c l u s i o n s . A wide v a r i a t i o n i n l i q u i d t o vapour r a t i o s i n i n c l u s i o n s and b r e c c i a t e x t u r e s w i t h i n v e i n s a s s o c i a t e d with p r e c i o u s metals a l s o supports the occurrence of b o i l i n g . 159 Depths -of emplacement f o r b o i l i n g f l u i d s were c a l c u l a t e d u s i n g equations developed by Haas (1971). C o n s i d e r i n g c o n d i t i o n s between extreme h y d r o s t a t i c or l i t h o s t a t i c ( F i g . 3.38C), u s i n g a rock d e n s i t y of 0.8 g/cm , e a r l y - f o r m e d quartz carbonate v e i n s d e p o s i t e d a t depths near 100 m. T h i s c a l c u l a t e d depth i s l e s s than one k i l o m e t r e which i s c o n s i s t a n t w i t h the epithermal c h a r a c t e r of the v e i n s . S t a b l e i s o t o p e compositions of m i n e r a l s a t Wolf i n d i c a t e t h a t a h i g h degree of i s o t o p i c exchange between 1 Q w a l l r o c k and l a r g e volumes of low 0 content hydrothermal f l u i d s ( s e c t i o n 3.6.2). Oxygen and hydrogen i s o t o p e evidence shows t h a t hydrothermal s o l u t i o n s a t Wolf were meteoric i n o r i g i n with v i r t u a l l y no c o n t r i b u t i o n from magmatic sources ( F i g . 3.40). F l u i d e v o l u t i o n i s documented i n F i g u r e 3.41 as a h o r i z o n t a l l i n e w i t h early-formed quartz carbonate v e i n s p l o t t i n g f u r t h e s t from and l a t e - f o r m e d drusy quartz p l o t t i n g c l o s e s t t o the p r e s e n t day meteoric water l i n e . The s i z e of the hydrothermal c i r c u l a t i o n c e l l i s p r e d i c t e d by water t o rock r a t i o s which i n d i c a t e t h a t f o r every gram of a l t e r e d rock i n the area of the p r o s p e c t , a t l e a s t 0.27 t o 0.88 grams of water moved through the system i n i t s l i f e t i m e . C o n s e r v a t i v e l y , assuming an a l t e r e d area of 10 km 2 t o a depth of 700 m, the minimum amount of water t h a t passed through 50 percent of these rocks i s 2.55 * 1 0 1 2 kg. The p a l e o c l i m a t e i n the mid-Eocene was s u b t r o p i c a l (Rouse, 1977; Rouse and Mathews, 1979) which probably 160 c o n t r i b u t e d t o the v a s t q u a n t i t i e s of c i r c u l a t i n g f l u i d s a t Wolf. The source of m i n e r a l i z a t i o n a t Wolf i s probably the host Ootsa Lake Group v o l c a n i c rocks with minor c o n t r i b u t i o n from "basement" Hazelton Group roc k s . Henley (1985) and McDonald (1987) have suggested t h a t any rock type c o n t a i n s s u f f i c i e n t q u a n t i t i e s of p r e c i o u s metals, i n t r a c e amounts, to supply the t o t a l m e t a l l i c content t y p i c a l l y found i n most epi t h e r m a l d e p o s i t s many times over. F i e l d evidence, l a b o r a t o r y s t u d i e s , and t h e o r e t i c a l c o n s i d e r a t i o n s suggest t h a t l a r g e volumes of b o i l i n g , meteoric-hydrothermal f l u i d s c a r r y i n g scavanged p r e c i o u s metals from country rocks were focused i n t o s u i t a b l e s t r u c t u r e s , such as b l o c k and r i n g f a u l t s , c a u s i n g p e r v a s i v e a r g i l l i c a l t e r a t i o n and d e p l e t i o n of the rocks i n 1 8 0 a t the s i t e of hydrothermal d i s c h a r g e . P r e c i o u s metals were p r e c i p i t a t e d i n response t o sudden p r e s s u r e r e l e a s e accompanying f r a c t u r i n g and b r e c c i a t i o n of a p a r t i a l l y s e a l e d cap ( P ^ i t h p h y d ) • P e r i o d i c r e - a c t i v a t i o n of f a u l t s , as a r e s u l t of l i t h o s t a t i c p r e s s u r e b u i l d - u p , f r a c t u r e d p r e v i o u s s i l i c a s e a l e d caps and/or v e i n s , and l e a d t o r e p e t i t i v e d e p o s i t i o n of g o l d and quartz from b o i l i n g hydrothermal f l u i d s and r e - s e a l i n g of f a u l t s . P r e c i p i t a t i o n of s i g n i f i c a n t g o l d m i n e r a l i z a t i o n i s most c l o s e l y a s s o c i a t e d w i t h early-formed quartz carbonate v e i n s . With time and waning of the hydrothermal system, f l u i d s evolved t o n o n - b o i l i n g lower s a l i n i t y , extremely x o O d e p l e t e d , p r e c i o u s metal-poor v a r i e t y which p r e c i p i t a t e d l a t e drusy q u a r t z . CHAPTER 4 THE CAPOOSE BASE AND PRECIOUS METAL PORPHYRY-STYLE PROSPECT: GEOLOGY AND GENESIS 4.1 LOCATION AND ACCESS The Capoose p r e c i o u s and base metal p r o s p e c t i n c e n t r a l B r i t i s h Columbia ( F i g . 1.1) i s c e n t r e d a t l a t i t u d e 53°16 / n o r t h and l o n g i t u d e 125°09' west (N.T.S.: 93F/06), approximately 110 km southeast of Burns Lake and 170 km southwest of P r i n c e George. Access i s by h e l i c o p t e r , o r by four-wheel d r i v e road o f f k i l o m e t r e 142 on the main Kluskus-Ootsa l o g g i n g road running southwest from Vanderhoof. The c e n t r e o f the p r o p e r t y i s two k i l o m e t r e s n o r t h of Fawnie Nose ( F i g . 1.1). 4.2 GEOLOGY 4.2.1 INTRODUCTION The Fawnie Range, i n the v i c i n i t y of the Capoose pro s p e c t , i s a northwest-trending sequence of s y n c l i n a l l y f o l d e d Lower and Middle J u r a s s i c Hazelton Group rocks i n t r u d e d by Upper Cretaceous (67+ 2.3 Ma by K-Ar on whole rock) g a r n e t i f e r o u s r h y o l i t e s i l l s and a quartz monzonite b a t h o l i t h (64.3 + 2.4 Ma by K-Ar on b i o t i t e ) . The area s t u d i e d ( F i g . 2.1) l i e s w i t h i n Middle J u r a s s i c H a z e l t o n Group rocks i n f a u l t c o n t a c t with Lower J u r a s s i c H a z e l t o n Group rocks l e s s than two km t o the nor t h and south (Tipper 163 4.2.2 STRATIGRAPHY AND PETROLOGY Middle J u r a s s i c Hazelton Group rocks on the Fawnie Range are p r i m a r i l y i n t e r m e d i a t e v o l c a n i c flows and f e l s i c v o l c a n i c l a s t i c s with i n t e r c a l a t e d sediments. I n t r u s i v e i n t o these rocks are Upper Cretaceous g a r n e t i f e r o u s r h y o l i t e s i l l s and f e l s i t e dykes. D e t a i l e d mapping a t a s c a l e of 1:2500 and core l o g g i n g of a r e p r e s e n t a t i v e c r o s s - s e c t i o n on the Capoose p r o p e r t y d e f i n e d the 10 map u n i t s i n the main area of m i n e r a l i z a t i o n shown on F i g u r e 4.1. Summarized p e t r o g r a p h i c d e s c r i p t i o n s of rock u n i t s f o l l o w . Map u n i t s are grouped i n t o f o u r assemblages (Table 4.1) based on s p a t i a l r e l a t i o n s h i p s , s i m i l a r d e p o s i t i o n a l environments, complementary l i t h o l o g i e s and a s s o c i a t e d t e x t u r e s . The assemblages, from o l d e s t t o youngest, a r e : (1) mafic v o l c a n i c rocks ( u n i t 1), (2) v o l c a n i c l a s t i c and sedimentary rocks ( u n i t s 2 t o 5), (3) f e l s i c v o l c a n i c rocks ( u n i t s 6 t o 8), and (4) dykes ( u n i t s 9 and 10). U n i t s are c o r r e l a t e d , where p o s s i b l e , with Middle J u r a s s i c H a z e l t o n Group s u b d i v i s i o n s i n n o r t h - c e n t r a l B r i t i s h Columbia of T i p p e r and Richards (1976). M a f i c v o l c a n i c rocks ( u n i t 1) crop out i n the n o r t h e a s t e r n p a r t of the map area ( F i g . 4.1). These are t y p i c a l l y massive, but l o c a l l y s c o r i a c e o u s , b a s a l t i c -a n d e s i t e flows. Some i n t e r f l o w b r e c c i a , w i t h f e l s i c , a l t e r e d f e l s i c and dark b a s a l t i c fragments, i s i n c l u d e d i n the u n i t . The flows are c h a r a c t e r i s e d by 10% euhedral 164 FIGURE 4.1: Geology of the Capoose pr o s p e c t , Capoose Lake area, c e n t r a l B r i t i s h Columbia. C r o s s - s e c t i o n s A-A' and B-B are i n F i g u r e s 4.2 and 4.3, r e s p e c t i v e l y . 1 6 5 L E G E N D Lower Jurassic Hazelton Group basa l t ic andes i te f l ow, f low b r e c c i a Middle Jurassic Hazelton Group fe l s i c lapilli tuff Upper Cretaceous intrusions quartz garnet rhyo l i t e si l l g a r n e t rhyo l i te sill d a c i t e f low rhyol i te sill thinly i n te rbedded argi l l i te - a sh tuff quartz garnet porphyry lithic wacke f e l s i te S Y M B O L S geological contact defined, assumed fault defined, assumed 40 flow banding 30 glacial striae 20 bedding diamond drill hole FIGURE 4.1: Geology of the Capoose p r o s p e c t , Capoose Lake area, c e n t r a l B r i t i s h Columbia. C r o s s - s e c t i o n s A-A' and B-B' are i n F i g u r e s 4.2 and 4.3, r e s p e c t i v e l y . 166 TABLE 4.1: Grouping of map u n i t s based on s p a t i a l r e l a t i o n -s h i p , complementary l i t h o l o g y , s i m i l a r i t y o f d e p o s i t i o n a l environment, and a s s o c i a t e d t e x t u r e s , Capoose prospect, c e n t r a l B r i t i s h Columbia. MAP LITHOLOGY TEXTURES DEPOSITIONAL ASSEMBLAGE UNIT ENVIRONMENT 1 b a s a l t i c - a n d e s i t e flows, flow b r e c c i a 2 l a p i l l i t u f f 3 d a c i t e flow 4 a r g i l l i t e and ash t u f f 5 l i t h i c wacke 6 quartz garnet r h y o l i t e 7 garnet r h y o l i t e 8 r h y o l i t e 9 quartz garnet porphyry 10 f e l s i t e massive, l o c a l l y scoreaceous 20% fragments s p h e r u l i t i c massive graded bedding, l o a d c a s t s broken rock fragments massive, a p h a n i t i c subaqueous s u b a e r i a l s u b a e r i a l m a fic v o l c a n i c rocks v o l c a n i -c l a s t i c v o l c a n i c -c l a s t i c submarine sedimentary fan and v o l c a n i -c l a s t i c submarine fan massive, a p h a n i t i c massive, a p h a n i t i c p o r p h y r i t i c a p h a n i t i c , m i c r o s p h e r u l i t i c sedimentary f e l s i c v o l c a n i c r o c k s f e l s i c v o l c a n i c rocks f e l s i c v o l c a n i c rocks dykes dykes p l a g i o c l a s e ( A n 8 0 _ g 5 ) and almost complete replacement o f mafi c s m i n e r a l s by up t o 30% c h l o r i t e . M i c r o l i t e s of f e l d s p a r make up a f e l t t e x t u r e d matrix. L o c a l l y , up t o 25% s t r e t c h e d amygdales (1 by 2 cm) are i n f i l l e d mainly by c a l c i t e and quar t z , and have a n o r t h e a s t e r l y e l o n g a t i o n . T h i s u n i t c o u l d r e p r e s e n t a d i s t a l f a c i e s t o the subaqueous v o l c a n i c s o f the E a r l y J u r a s s i c Ankwell Member of the N i l k i t k w a Formation d e s c r i b e d by T i p p e r and Rich a r d s (1976). V o l c a n i c l a s t i c and sedimentary rocks (units 2 to 5) conformably o v e r l i e the b a s a l t i c a n d e s i t e and c o n s i s t of f e l s i c l a p i l l i t u f f s interbedded w i t h d a c i t e flows, a r g i l l i t e and l i t h i c wacke. L a p i l l i t u f f ( u n i t 2) supports up t o 20% f e l s i c fragments (1 t o 10 mm across) i n a p a l e grey matrix o f f e l d s p a r m i c r o l i t e s . D e v i t r i f i c a t i o n has r e s u l t e d i n a p h a n i t i c and p o o r l y formed s p h e r u l i t i c f a b r i c s . A d a c i t e flow ( u n i t 3) i n the n o r t h e a s t e r n p a r t o f the study area, shows conformable c o n t a c t s w i t h bedding i n adj a c e n t l i t h i c wacke and f e l s i c l a p i l l i t u f f . T h i s u n i t looks l i k e a n d e s i t e i n hand specimen, but i n t h i n s e c t i o n has 1% anhedral embayed quartz c r y s t a l s . The f e l t - t e x t u r e d m a t r i x w i t h 1% opaques surrounds a phenocryst assemblage of 5% b i o t i t e ( p r e f e r e n t i a l l y r e p l a c e d by c h l o r i t e ) and 2% p l a g i o c l a s e ( A n 5 0 _ 7 0 ) . T h i n l y bedded a r g i l l i t e and ash t u f f  ( u n i t 4) outcrops i n the c e n t r a l p o r t i o n o f the ar e a . T u f f beds range from 1 t o 5 cm t h i c k and are interbedded w i t h 10 cm t h i c k a r g i l l i t e beds. I n d i c a t o r s o f tops, such as graded bedding, l o a d c a s t s , r i p - u p c l a s t s and p u l l - a p a r t s t r u c t u r e s are common and show the s e c t i o n t o be r i g h t - s i d e - u p . Breakdown of c a l c i c f e l d s p a r s i n the ash t u f f has r e s u l t e d i n a c a l c i t i c matrix cementing up t o 15% broken, corroded p l a g i o c l a s e c r y s t a l s and 5% opaques. L i t h i c wacke ( u n i t 5) i s p o o r l y s o r t e d w i t h approximately 60% matrix and rock fragments, 20% angular f e l d s p a r g r a i n s and 2 0% quartz g r a i n s . Rocks of t h i s composition are c h i e f l y v o l c a n i c sandstones formed by d i r e c t reworking of p y r o c l a s t i c m a t e r i a l . Discontinuous beds of limey a c c r e t i o n a r y l a p i l l i t u f f p i n c h and s w e l l i n outcrop. L o c a l l y t h i s u n i t c o n t a i n s abundant f o s s i l s , some of which have been i d e n t i f i e d by H. F r e b o l d o f the G e o l o g i c a l Survey of Canada ( s e c t i o n 4.4.1) as Belemnites, s p e c i e s indeterminate, and Rhynchonella, s p e c i e s indeterminate (Tipper, 1963; P l a t e 4.1). Rec e n t l y , H.W. T i p p e r a t the G e o l o g i c a l Survey o f Canada (pers. comm., 1987) has suggested a Middle J u r a s s i c C a l l o v i a n (163 t o 169 Ma) age f o r these f o s s i l s . These v o l c a n i c l a s t i c s and sediments, e s p e c i a l l y u n i t 4, may c o r r e l a t e w i t h the Yuen Member of the Smithers Formation i n the Middle J u r a s s i c H a z e l t o n Group d e s c r i b e d by T i p p e r and Rich a r d s (197 6). F e l s i c volcanic rocks (units 6 to 8) occur as s i l l s , 10 to 400 m t h i c k , i n t r u s i v e i n t o the v o l c a n i c l a s t i c s and sediments ( P l a t e 4.2). The package i s c h a r a c t e r i s e d by a sequence of flow-banded, s p h e r u l i t i c , g a r n e t i f e r o u s quartz r h y o l i t e and r h y o l i t e i n t r u s i v e s d i p p i n g 30° t o the southwest. (Garnet o r i g i n i s d i s c u s s e d i n s e c t i o n 4.5.) Quartz garnet r h y o l i t e ( u n i t 6) of the youngest s i l l i s PLATE 4.1: C a l l o v i a n b e l e m n i t e s i n l i t h i c wacke ( u n i t 5; F i g . 4.1) of t h e Smithers Formation, H a z e l t o n Group, Capoose p r o s p e c t . PLATE 4.2: C h i l l e d c o n t a c t o f q u a r t z g a r n e t r h y o l i t e s i l l ( u n i t 6; F i g . 4.1) a d j a c e n t t o h o r n f e l s e d a r g i l l i t e - t u f f ( u n i t 4; F i g . 4.1), Capoose p r o s p e c t . c h a r a c t e r i s e d by 7% embayed quartz phenocrysts (1 t o 2 mm i n diameter) and 3% anhedral garnet c r y s t a l s i n a d e v i t r i f i e d , f e l t - t e x t u r e d a p h a n i t i c groundmass. The garnets are o c c a s i o n a l l y zoned, e x h i b i t weak b i r e f r i n g e n c e , are intergrown by muscovite, and are rimmed by muscovite and qua r t z . Garnet r h y o l i t e ( u n i t 7) i s commonly flow banded and c o n t a i n s s p h e r u l i t e - l i k e b a l l s (1 t o 3 cm i n diame t e r ) . Lithophysae, seen i n t h i n s e c t i o n , are o f t e n l i n e d w i t h q u a r t z . T h i s u n i t has 5% anhedral garnets interwoven w i t h quartz aggregates and surrounded by f e l d s p a r m i c r o l i t e s . R h y o l i t e ( u n i t 8) i s predominantly a p h y r i c . However, 1 t o 2% anhedral garnet c r y s t a l s are a s s o c i a t e d w i t h r a r e s p h e r u l i t e - l i k e b a l l s , 5 t o 30 cm i n diameter c l o s e t o a u t o b r e c c i a t e d zones. Flow banding i s common i n t h i s u n i t . Most of the u n i t i s s e r i c i t i z e d ; disseminated p y r i t e i s common. G a r n e t i f e r o u s r h y o l i t e s were r e p o r t e d by S c h r o e t e r (1981) a t Capoose and assigned t o the Hazelton Group. However, no other documentation t h i s rock type has been r e p o r t e d i n Hazelton Group l i t e r a t u r e , or f o r any oth e r J u r a s s i c or Cretaceous Group i n B r i t i s h Columbia. Dykes ( u n i t s 9 and 10) c r o s s c u t a l l o t h e r u n i t s . A quartz garnet p o r p h y r i t i c dyke ( u n i t 9) d i p s s h a l l o w l y t o the southwest and i s c h a r a c t e r i s e d by 1% anhedral garnet and 5% corroded quartz c r y s t a l s i n a matrix of e q u i g r a n u l a r quartz and f e l d s p a r . The rims of quartz and muscovite surrounding garnets are l e s s d i s t i n c t than i n o l d e r r h y o l i t e u n i t s . A cream-coloured f e l s i t e dyke ( u n i t 10) c r o s s c u t s a l l u n i t s on the pr o p e r t y . I t i s marked by p l a t y r u b b l e subcrop (denoted by c r o s s e s i n F i g . 4.1). In t h i n s e c t i o n , d e v i t r i f i c a t i o n i s represented by m i c r o s p h e r u l i t e s i n an a p h a n i t i c groundmass. 4.2.3. STRUCTURE The Hazelton Group i s c h a r a c t e r i z e d by open f o l d i n g w i t h d i p s up t o 45°. In the v i c i n i t y o f the Capoose pro s p e c t , rocks are s y n c l i n a l l y f o l d e d ; the a x i s of the s y n c l i n e t r e n d s northwest and passes 5 km northwest of the c e n t r e o f the study area (Tipper e t a l . , 1979). D e t a i l e d mapping of the n o r t h e a s t e r n limb of the s y n c l i n e on Fawnie Range shows u n i t s d i p p i n g 20 t o 4 0° t o the southwest. Measurement of cleavage-bedding i n t e r s e c t i o n s i n the a r g i l l i t e - t u f f , and s t e e p l y d i p p i n g A-C j o i n t s u r f a c e s i n f e l s i c t u f f s and d a c i t e s i n d i c a t e s t h a t the s y n c l i n a l f o l d a x i s plunges g e n t l y (10°) southeast. East-west f a u l t s dominate r e g i o n a l s t r u c t u r e s i n the area. F a u l t t r a c e s are marked by l i n e a r d e p r e s s i o n s on Fawnie Range (Schroeder, 1981). D e t a i l e d mapping has d e f i n e d two n o r t h e a s t - t r e n d i n g d i p - s l i p f a u l t s which appear t o mark the boundaries o f a minor h o r s t ( s e c t i o n A-A': F i g . 4.2). S e c t i o n B-B' ( F i g . 4.3) i l l u s t r a t e s the s t r a t i g r a p h y of the n o r t h e a s t e r n limb of the Fawnie Range s y n c l i n e . 4.2.4 METAMORPHISM SE NW FIGURE 4.2: Cross s e c t i o n A-A' ( F i g . 4.1) a c r o s s t h e main zone on the Capoose property d e f i n i n g two n o r t h e a s t - t r e n d i n g d i p - s l i p f a u l t s which mark the boundaries o f a minor h o r s t . to NE SW FIGURE 4.3: Cross s e c t i o n B-B' ( F i g . 4.1) a c r o s s the northwestern limb of the Fawnie Range s y n c l i n e showing s t r a t i g r a p h i c r e l a t i o n s h i p s Rocks of the Nechako P l a t e a u are c h a r a c t e r i z e d by low-grade r e g i o n a l metamorphism. Contact metamorphism around p l u t o n s i s pronounced (Tipper, 1963). On Fawnie Range, mafic v o l c a n i c rocks have been s u b j e c t e d t o r e g i o n a l g r e e n s c h i s t metamorphism as evidenced by the breakdown of pyroxene and amphibole t o c h l o r i t e and by the s a u s s u r i t i z a t i o n of p l a g i o c l a s e . The o n l y p r e s e r v e d t r a c e s of o r i g i n a l t e x t u r e are amygdales f i l l e d by c a l c i t e and q u a r t z . V e i n l e t s of c a l c i t e (up t o 1 mm i n diameter) are common. V o l c a n i c l a s t i c and sedimentary rocks adjacent t o the r h y o l i t e s i l l s have been t h e r m a l l y metamorphosed. Although these t y p i c a l l y f i n e - g r a i n e d l i t h i c wacke, a r g i l l i t e and ash t u f f u n i t s are h o r n f e l s e d , bedding i s d i s t i n c t . 4.3 PETROCHEMISTRY T h i r t e e n rock samples from the Capoose p r o p e r t y were analysed f o r major, minor and t r a c e element c o n c e n t r a t i o n s . Sample l o c a t i o n s are p l o t t e d i n F i g u r e 4.4 and p e t r o g r a p h i c d e s c r i p t i o n s are i n Appendix IB. Trace element data are not i n t e r p r e t e d because most are below the d e t e c t i o n l i m i t . 4.3.1. SAMPLE PREPARATION AND ANALYSIS A l l rock samples were broken t o c h i p - s i z e i n a jaw crusher, s p l i t and p u l v e r i z e d t o < 200 mesh i n a tungsten c a r b i d e r i n g m i l l . Approximately 100 g of sample was sent t o Cominco L t d . f o r X-ray f l u o r e s c e n c e (XRF), atomic 175 FIGURE 4.4: Whole rock and t r a c e element chemical a n a l y s e s sample l o c a t i o n s , Capoose p r o p e r t y , Capoose Lake area. 176 a b s o r p t i o n spectrometry (AAS), c o l o u r i m e t r i c , and v o l u m e t r i c a n a l y s e s a t t h e i r l a b o r a t o r y i n Vancouver, B r i t i s h Columbia. Analyses o f major and minor elements were undertaken by XRF and r e p o r t e d as weight percent oxide; water and C0 2 e t c . were r e p o r t e d as l o s s on i g n i t i o n (LOI) (Appendix I B ) . Trace elements determined i n c l u d e : Ag, As, Ba, Cr, La, Nb, Ni , Pb, Rb, S, Sb, Se, Sr, Te, U, V, Y and Zn. Elemental data are r e p o r t e d i n ppm (Appendix 1A). Analyses o f Ag, Cr, Ni , Pb, Sb, Se, Te and Zn were made u s i n g AAS. A r s e n i c was determined by the c o l o r i m e t r i c technique and su l p h u r by v o l u m e t r i c a n a l y s i s . The remaining t r a c e elements were analysed by XRF. C o n t r o l samples c o n s i s t of two p a i r s of f i e l d d u p l i c a t e s and one UBC i n t e r n a l standard (Table 4.2). The f i e l d d u p l i c a t e samples were used t o determine the amount of combined sampling, p r e p a r a t i o n and a n a l y t i c a l e r r o r f o r each a n a l y s i s . The i n t e r n a l standard sample was used t o determine a n a l y t i c a l accuracy. 4.3.2. ERROR ANALYSIS Samples c o l l e c t e d as d u p l i c a t e s were e v a l u a t e d t o determine the p r e c i s i o n o f the geochemical a n a l y s e s . I n t e r n a l standard samples were chosen t o t e s t a n a l y t i c a l accuracy. A l i s t i n g of c o n t r o l sample data i s pres e n t e d i n Table 4.2. The d u p l i c a t e analyses have e x c e l l e n t p r e c i s i o n . Combined r e l a t i v e e r r o r s f o r most elements are below 5%. 177 TABLE 4.2: D u p l i c a t e data and U n i v e r s i t y o f B r i t i s h Columbia standard samples used t o determine p r e c i s i o n and accuracy o f geochemical analyses a t the Capoose pro s p e c t , c e n t r a l B r i t i s h Columbia. SAMPLE NUMBER KCP009 TCP009 WP1 Dl D2 S CXIDES (Wt. %) S i 0 2 78.51 78-61 65.12 A 1 2 0 3 12.46 12.36 16.41 T l 0 2 0.11 0.11 0.48 F e 2 0 3 0.86 0.85 4.41 MgO 0.05 0.18 2.65 CaO 0.52 0.52 4.94 Na 20 0.02 0.05 4.21 K 20 4.39 4.39 1.63 MnO 0.48 0.45 0.07 P 2 ° 5 0.02 0.02 0.13 TRACE ELEMENTS (ppm) Ag — . - <0.4 As - <2 Ba 219 209 609 Cr <5 <5 51 La <20 <20 <20 Nb <20 <20 <20 Ni <4 <4 40 Rb 129 76 <20 Sb - - <4 Sr 27 238 750 U <20 <20 <20 V <20 <20 80 Y <20 <20 <20 E r r o r s - f o r major, minor and t r a c e elements are 3%, 5%, and 10% r e s p e c t i v e l y . Sampling v a r i a t i o n w i t h i n an outcrop does not seem t o have s i g n i f i c a n t l y a f f e c t e d the a n a l y s e s . P r e p a r a t i o n e r r o r a s s o c i a t e d w i t h the analyses probably i n c l u d e s Fe contamination from the jaw c r u s h e r and t r a c e Cr contamination from the tungsten c a r b i d e r i n g m i l l (Hickson and J u r a s , 1986). A n a l y t i c a l e r r o r , such as contamination and a n a l y t i c a l d r i f t , i s accounted f o r i n the e r r o r a n a l yses of r e p l i c a t e samples, which were not analysed s e q u e n t i a l l y . 4.3.3. ELIMINATION OF MOST ALTERED DATA A l t e r e d rocks from the Capoose p r o p e r t y were i d e n t i f i e d by u s i n g weight percent oxide data from Appendix IB and p l o t t i n g on diagrams m o n i t o r i n g metasomatism of i n d i v i d u a l samples (Beswick, 1978; de Rosen-Spence, 1976). T h i s approach i s necessary because d e u t e r i c and metamorphic processes can a f f e c t the a l k a l i e s , magnesium, c a l c i u m and p o s s i b l y the content of o t h e r elements upon which chemical c l a s s i f i c a t i o n s depend. Logarithms of major oxide molecular p r o p o r t i o n s of a wide range of modern v o l c a n i c rocks d e f i n e d i s t i n c t t r e n d s on m o l e c u l a r p r o p o r t i o n r a t i o diagrams (Beswick, 1978). S i n c e these t r e n d s were d i s t i n g u i s h e d i r r e s p e c t i v e of the chemical c l a s s i f i c a t i o n of rocks from the a n a l y t i c a l data bank, they are i n s e n s i t i v e t o the d i f f e r e n c e s i n the d e t a i l e d f r a c t i o n a t i o n h i s t o r y of the rock s u i t e s (Beswick, 1978). Most samples from the Capoose p r o p e r t y p l o t w i t h i n the t i g h t l y d e f i n e d trends of modern v o l c a n i c rocks ( F i g . 4.5, Table 4.3). Samples, e s t a b l i s h e d as a l t e r e d , f o l l o w i n g the above analyses, were d e l e t e d from Appendix IB and from chemical c l a s s i f i c a t i o n p l o t s i n s e c t i o n 4.3.4. Least a l t e r e d samples are i n Table 4.3. 4.3.4. CHEMICAL ROCK CLASSIFICATION Rocks on the Capoose p r o p e r t y were named c o n v e n t i o n a l l y , above, u s i n g d e s c r i p t i v e f i e l d terms combined wi t h modal p e t r o g r a p h i c i n f o r m a t i o n (Table 4.1). L e a s t a l t e r e d rocks are c l a s s i f i e d more f u l l y on the b a s i s of major and t r a c e element geochemistry. Capoose v o l c a n i c rocks are dominantly hypersthene-corundum normative (Table 4.3). In the i n t e r m e d i a t e v o l c a n i c s u i t e a t Capoose (GCP013 and GCP018), g e n e r a l l y h i g h a n o r t h i t e content i n the norm matches modal p l a g i o c l a s e d e t e r m i n a t i o n s of A n 5 0 _ 9 0 (Table 4.3). F e l s i c v o l c a n i c normative compositions are s i m i l a r (Table 4.3). Capoose f e l s i c v o l c a n i c rocks are s u b a l k a l i n e ( F i g . 4.6; MacDonald, 1968; I r v i n e and Baragar, 1971). The AFM diagram of F i g u r e 4.7 demonstrates the c a l c a l c a l i n e a f f i n i t y . A c a l c a l k a l i n e t r e n d i s a l s o e v i d e n t i n F i g u r e 4.8, the Jensen p l o t (Jensen, 1976). T o t a l i r o n , a nalysed as F e 2 0 3 , was converted t o weight percent FeO and F e 2 0 3 u s i n g the method of Sack e t a l . (1980). The c a l c u l a t i o n s 180 -2 -J 1 1 1 1 - ) - 2 - 1 0 1 2 3 log Fm / K 2 0 FIGURE 4.5: L o g a r i t h m i c oxide m o l e c u l a r p r o p o r t i o n r a t i o p l o t s (K 20 denominator) f o r comparison of Capoose v o l c a n i c rocks t o 'modern' v o l c a n i c s u i t e s and r e t r i e v a l of l e a s t a l t e r e d data (Beswick, 1978). Most dots which represent r o c k s from the Capoose p r o s p e c t (Appendix IB) f a l l predominantly w i t h i n the l i m i t s f o r 'modern' v o l c a n i c s u i t e s . Least a l t e r e d rocks are i n T a b l e 3.3. 181 TABLE 4.3: Least a l t e r e d samples used f o r rock c l a s s i f i c a t i o n and chemical c l a s s i f i c a t i o n , Capoose prospect, c e n t r a l B r i t i s h Columbia. SAMPLE NUMBER KCP009 KCP012 KCP020B KCP035 -KCP044 KCP054 OXIDES (Wt. %) S i 0 2 78.51 76.93 78.10 76.26 76. 79 75. 53 A 1 2 0 3 12.46 13.23 12.08 13.13 13. 67 13 . 09 T i 0 2 i 0.11 0.12 0.11 0.06 0. 29 0. 14 0.86 1.29 0.89 0.48 1. 28 2. 00 MgO 0.05 0.29 0.13 0.02 0. 30 0. 16 CaO 0.52 0.13 0.19 0.16 0. 09 0. 06 Na 20 0.02 0.02 0.09 3.31 0. 14 0. 02 K 20 4 . 39 4.05 5.44 4.84 4. 36 3 . 90 MnO 0.48 1.55 1.45 0.06 0. 72 2 . 95 P 2 ° 5 0. 02 0.02 0.02 0.02 0. 02 0. 02 LOI 1.87 2.18 1.42 1.34 2. 14 2. 33 t o t a l 99.29 99.81 99.92 99.68 99. 80 100. 20 CIPW NORM Q 60. 09 59.51 54.40 36.35 58.08 58. 30 c 7.94 10.10 6.65 2.47 10..03 10. 30 Or 27.83 25.65 34.07 29.40 27.51 24. 78 (Ab) 0.19 0.19 0.86 30.56 1.34 0. 19 (An) 2.63 0.55 0.86 0.68 0.34 0. 18 (En) 0.15 0.86 0.38 0.06 0.88 0. 00 (Fs) 0.00 1.46 1.59 0.00 0. 00 0. 00 11 0.16 0.18 0.16 0.09 0.43 0. 21 Hm 0.00 0.00 0.00 0.33 0.18 0. 00 Mt 0.96 1.45 0.99 0.02 1.16 2. 25 Ap 0.04 0.04 0.04 0.04 0.04 0. 04 1. T o t a l i r o n i s expressed as F e 2 0 SiO, wt % FIGURE 4.6; P l o t of a l k a l i e s v s . s i l i c a f o r a n a l y s e s from the Capoose pr o p e r t y (Table 4.3, boundaries are from MacDonald, 1968, and I r v i n e and Baragar, 1971). Assemblages are s u b - a l k a l i n e ( s e c t i o n 4.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s and c i r c l e s = dykes. 183 FIGURE 4.7: AFM diagram w i t h analyses from the Capoose p r o p e r t y (Table 4.3, boundaries are from Wager and Deer, 1939). Assemblages are c a l c - a l k a l i n e ( s e c t i o n 4.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c s , diamonds = v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s and c i r c l e s = dykes. 184 FIGURE 4.8: Jensen C a t i o n p l o t f o r a nalyses from the Capoose p r o s p e c t (Table 4.3, boundaries are from Jensen, 1976). Assemblages are dominantly c a l c - a l k a l i n e ( s e c t i o n 4.2.2) and are p l o t t e d u s i n g : squares = m a f i c v o l c a n i c s , diamonds = v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s , c i r c l e s = dykes. 185 were made a t 800°C and l n f 0 2 of 1 0 ~ 1 4 (from f i g u r e 6-12 i n Carmichael e t a l . , 1974). Rocks from the Capoose p r o p e r t y p l o t as o v e r s a t u r a t e d t o s a t u r a t e d a c i d v o l c a n i c s dominantly w i t h i n the r h y o l i t e and d a c i t e f i e l d s on F i g u r e 4.9 (LeBas e t a l . , 1986). Samples c l u s t e r as r h y o l i t e s and d a c i t e s on the Jensen p l o t ( F i g . 4.8) and the " t r i a x i a l oxide" p l o t i n F i g u r e 4.10 (Church, 1975). T e c t o n i c d e s c r i m i n a t i o n diagrams, d e f i n e d g e n e r a l l y f o r b a s a l t i c rocks, cannot be a p p l i e d t o the f e l s i c v o l c a n i c rocks from the Capoose p r o p e r t y . However, Capoose r h y o l i t e s i l l s p l o t as high-K on the K 20 v s . S i 0 2 diagram of G i l l (1981), m o d i f i e d t o i n c l u d e r h y o l i t e s ( F i g . 4.11; Spence, 1985). T h i s t h e s i s c h e m i c a l l y c l a s s i f i e s g a r n e t i f e r o u s r h y o l i t e s i l l s which i n t r u d e Middle J u r a s s i c H a z e l t o n Group rocks a t Capoose u s i n g whole rock and t r a c e element chemistry. P r e v i o u s l i t h o g e o c h e m i c a l analyses from Capoose were l i m i t e d t o metals and sulphur (Church and Diakow, 1982) . R h y o l i t e s a t Capoose are predominantly o v e r s a t u r a t e d f e l s i c v o l c a n i c rocks of c a l c a l k a l i n e a f f i n i t y . S i 0 2 v a l u e s are between 68 and 79% (Table 4.3). The g a r n e t i f e r o u s r h y o l i t e s have a h i g h p r o p o r t i o n of manganese w i t h v a l u e s from 0.5 t o 3% MnO. The o n l y two whole rock chemical analyses of H a z e l t o n Group b a s a l t i c - a n d e s i t e s (GCP013 and GCP018) from the 186 FIGURE 4.9: P l o t of a l k a l i e s v s . s i l i c a f o r a n a l y s e s from the Capoose p r o p e r t y (Table 4.3, boundaries are from Le Bas e t a l . , 1986). Assemblages are ' r h y o l i t e s ' ( s e c t i o n 4.2.2) arid are p l o t t e d u s i n g : squares = mafic v o l c a n i c s diamonds = v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s and c i r c l e s = dykes. 187 35 CVJ O fO o CVJ 09 30 O a O + % 25 20 15 A B R Andesite Basalt Dacite Rhyolite 0 -.2 AI203/S102 .4 FIGURE 4.10: T r i a x i a l oxide p l o t ( F e 2 0 3 + FeO + 1/2 (MgO + CaO) vs. A l 2 0 3 / S i 0 2 ) w i t h analyses from the Capoose prospect (Table 4.3). Assemblages are ' r h y o l i t e s ' ( s e c t i o n 4.2.2) and are p l o t t e d u s i n g : squares = mafic v o l c a n i c diamonds = v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s and c i r c l e s = dykes. 188 wt % K 2 0 12 40 45 50 55 60 65 70 75 80 wt % SI0 2 FIGURE 4.11: K 20 v s . S i 0 2 p l o t f o r analyses from the Capoose pr o s p e c t (Table 4.3, boundaries are from de Rosen-Spence, 1976). A b r e v i a t i o n s a re: LK = low potassium, MK = medium potassium, HK = h i g h potassium, VHK = very h i g h potassium, EHK = extremely h i g h potassium. R h y o l i t e s i l l s have h i g h (HK) potassium ( s e c t i o n 4.2.2) and are p l o t t e d u s i n g the f o l l o w i n g symbols: squares = mafic v o l c a n i c s , diamonds = v o l c a n i c l a s t i c s , t r i a n g l e s = r h y o l i t e s i l l s and c i r c l e s = dykes. 189 Capoose. area have whole rock analyses c h e m i c a l l y s i m i l a r t o b a s a l t s r e p o r t e d by T i p p e r and Richards (1976). Capoose g a r n e t i f e r o u s r h y o l i t e s i l l s are c h e m i c a l l y d i s t i n c t from Kasalka Group (Maclntyre, 1976, Spence, 1987) and Hazelton Group v o l c a n i c rocks (Tipper and R i c h a r d s , 1976). The h i g h manganese v a l u e s i n whole rock data a t Capoose are r e l a t e d t o s p e s s a r t i n e ( s e c t i o n 4.5) garnet i n the r h y o l i t e s i l l s . Such hi g h MnO v a l u e s have not been r e p o r t e d i n the l i t e r a t u r e f o r r h y o l i t e s of any J u r a s s i c or Cretaceous Group. (The o r i g i n o f these Mn-rich garnets i s d i s c u s s e d i n s e c t i o n 4.5.) 4.4. DATING 4.4.1. RECENT FOSSIL IDENTIFICATION F o s s i l s were c o l l e c t e d by T i p p e r (1963) from the l i t h i c wacke ( u n i t 5) about 4 km from the nor t h end of Fawnie Nose. These were i d e n t i f i e d by H. F r e b o l d (Tipper, 1963: No. 4 GSC L o c a l i t y 20116-2) as Belemnites, s p e c i e s indeterminate, and Rhyncholnella, s p e c i e s indeterminate ( P l a t e 4.1) and as s i g n e d o n l y t o a b r o a d l y J u r a s s i c t o Cretaceous age. Recent p e r s o n a l communication (1987) wi t h H.W. T i p p e r a t the G e o l o g i c a l Survey of Canada has l e d t o an i n f e r r e d C a l l o v i a n (163 t o 169 Ma) age f o r these f o s s i l s . 4.4.2. K-AR Four samples from the Capoose p r o p e r t y were dated, t h r e e by whole rock K-Ar and one by K-Ar u s i n g b i o t i t e 190 (Table—4..4) . The samples dated by whole rock K-Ar were: (1) a quartz garnet r h y o l i t e s i l l (KCP009: u n i t 6), (2) a r h y o l i t e s i l l (KAD042: u n i t 8), and (3) a f e l s i t e dyke (KCP035: u n i t 10). The Capoose b a t h o l i t h , a quartz monzonite i n t r u s i v e 5 km northwest of the pro p e r t y , was dated by K-Ar u s i n g b i o t i t e . The purpose of the d a t i n g was t o o b t a i n an age f o r the r h y o l i t e s i l l s , dyke and b a t h o l i t h a t Capoose, and t o c o n f i r m f i e l d evidence t h a t the r h y o l i t e s i l l s r e p r e s e n t a younger i n t r u s i v e event u n r e l a t e d t o Ha z e l t o n Group s t r a t i g r a p h y . The K analyses were by atomic a b s o r p t i o n (by D. Runkle), and the Ar analyses were by i s o t o p e d i l u t i o n u s i n g c o n v e n t i o n a l procedures (by J . H a r a k a l ) . The decay co n s t a n t s used are X e + Xe< = 0.581 * 1 0 ~ 1 0 y e a r " 1 ; ^ = 4.962 * 1 0 ~ 1 0 y e a r " 1 ; and 4 0K/K = 1.167 * 10~ 2 atomic p e r c e n t ( S t e i g e r and Jager, 1977). Whole rock K-Ar d a t i n g of two r h y o l i t e s i l l s from the Capoose p r o p e r t y y i e l d e d dates of 68.4 Ma t o 70.3 Ma (Table 4.4). These Upper Cretaceous dates c o n f i r m f i e l d evidence t h a t the r h y o l i t e s are not r e l a t e d t o Middle J u r a s s i c H a z e l t o n Group s t r a t i g r a p h y , but r e p r e s e n t a younger i n t r u s i v e event. I t i s u n c l e a r whether the s i l l s are comagmatic wi t h the Capoose b a t h o l i t h which has been dated a t 67.1 Ma. T h i s t o p i c i s addressed i n s e c t i o n 4.5. The youngest u n i t on the pro p e r t y , a f e l s i t e dyke, dated a t 64.3 Ma and probably r e p r e s e n t s the waning stages of i n t r u s i v e a c t i v i t y a t Capoose. 191 TABLE 4.4: K-Ar ages f o r Capoose r h y o l i t e s i l l s , dykes and the Capoose b a t h o l i t h , Capoose prospect, c e n t r a l B r i t i s h Columbia. Samples are l o c a t e d on F i g u r e 4.4. SAMPLE LATITUDE/ K 4 0 A r r a d * 1 0 - 1 0 4 0 A r _ a d DATE 1 AGE2 NUMBER LONGITUDE (Wt.%) (moles/g) (%J (Ma) KCP009 quartz garnet r h y o l i t e whole rock 53°16 /50" 3.53 125°15 /10" 4.268 90.8 68.4±2.4 Late Creta-ceous KCP035 53°16 /30" 4.01 f e l s i t e 125°15 /40" whole rock KAD042 53°16 /40" 3.36 r h y o l i t e 125°15 /30" whole rock DVL190 grano-d i o r i t e b i o t i t e -s e parate 53°18 /30" 125°16 /30" 7.49 4.548 4.179 8.877 89.6 64.3+2.3 Late Creta-ceous 86.2* 70.3+2.5 Late Creta-ceous 97.5 67.1+2.3 Late Creta-ceous 1. Analyses were c a r r i e d out a t The U n i v e r s i t y o f B r i t i s h Columbia, Department o f G e o l o g i c a l S c i e n c e s , by K.R. S c o t t (K) and J . Harakal ( A r ) . 2. Age i s based on date and time s c a l e o f the DNAG 1983 Time S c a l e (Palmer, 1983). 192 4.4.3. GALENA LEAD ISOTOPES Galena l e a d i s o t o p e d a t i n g of a sample from the Capoose p r o p e r t y ( l a t i t u d e = 53°17 /40", l o n g i t u d e = 125°16'10" 2 0 6 p b / 2 0 4 / p b = 1 8. 9 0 3 , 2 0 7 P b / 2 0 4 P b = 15.601 and 2 0 8 P b / 2 0 4 P b = 38.482) p l o t s near the mid-point along the "Bridge R i v e r mixing l i n e " o f C. L e i t c h p e r s . comm. (1987). Although the mixing l i n e probably i n d i s t i n g u i s h a b l y spans Upper Cretaceous t o Middle Eocene time (90 Ma t o 50 Ma), the l e a d a n a l y ses a t Capoose do support a m i n e r a l i z i n g event a t about the same time o r j u s t a f t e r s i l l emplacement. 4.4.4. SUMMARY Potassium-argon d a t i n g has confirmed the i n t r u s i v e nature of g a r n e t i f e r o u s r h y o l i t e s on the Capoose p r o p e r t y . The r h y o l i t e s i l l s i n t r u d e C a l l o v i a n age l i t h i c wackes of the Hazelton Group i n l a t e s t Cretaceous time. Avenues o f d a t i n g emphasise the s i m i l a r i t y i n age of the Capoose b a t h o l i t h and m i n e r a l i z a t i o n on the p r o p e r t y . T h i s s t r e s s e s a probable g e n e t i c r e l a t i o n s h i p between these events. 4.5 ORIGIN OF GARNET IN RHYOLITE SILLS 4.5.1. I n t r o d u c t i o n I t i s r a r e t o f i n d garnets w i t h i n f i n e - g r a i n e d igneous r o c k s . The o r i g i n o f garnets i n c a l c - a l k a l i n e r h y o l i t e on Fawnie Range i s c r i t i c a l t o the i n t e r p r e t a t i o n o f the pe t r o g e n e s i s of the host rocks and has p o t e n t i a l t e c t o n i c i m p l i c a t i o n s . A number of o r i g i n s f o r garnet w i t h i n the Fawnie Range r h y o l i t e are eval u a t e d below u s i n g : (1) f i e l d r e l a t i o n s h i p s , (2) p e t r o g r a p h i c c h a r a c t e r i s t i c s , (3) microprobe compositions, (4) oxygen i s o t o p e compositions, and (5) l i t e r a t u r e comparisons. Garnets o f igneous, x e n o c r y s t i c , r e g i o n a l metamorphic and metasomatic o r i g i n s tend t o f a l l w i t h i n s p e c i f i c composition ranges, t o occur i n s p e c i f i c rock types, and t o be found p r e f e r e n t i a l l y i n c e r t a i n environments (Table 4.5). Igneous garnets occur as mainly almandine megacrysts (or phenocrysts) i n c a l c - a l k a l i n e f e l s i c v o l c a n i c s , and as spessartine-almandines (commonly y t t r i u m - r i c h ) i n f e l s i c i n t r u s i v e s such as a p l i t e s , a l a s k i t e s and g r a n i t e pegmatites (Miyashiro, 1955; I r v i n g and Frey, 1978). The garnets can occur as: (1) hig h p r e s s u r e phenocrysts which c r y s t a l l i z e d a t depth (P > 7kb: Green, 1978) and s u r v i v e d t r a n s p o r t t o h i g h e r c r u s t a l l e v e l s , (2) low t o moderate p r e s s u r e phenocrysts p r e c i p i t a t e d from d i f f e r e n t i a t e d ( M i l l e r and Stoddard, 1981) or contaminated (Bartrum, 1937) peraluminous magmas under low f 0 2 or f H 2 0 c o n d i t i o n s , o r (3) l a t e phase phenocrysts s t a b i l i z e d by h i g h Mn i n d i f f e r e n t i a t e d magmas ( M i l l e r and Stoddard, 1978). X e n o c r y s t i c garnets i n f e l s i c r o c k s, a c c o r d i n g t o Zeck (1970), can be from a n a t e c t i c r e s t i t e s t h a t r e p r e s e n t r e s i d i u m of the metamorphic t e r r a n e from which the igneous rock was l a r g e l y e x t r a c t e d . Regional metamorphic s p e s s a r t i n e - r i c h garnets are common i n g r e e n s c h i s t f a c i e s t e r r a n e s . Metasomatic s p e s s a r t i n e 194 TABLE 4.5: Compositions, host rocks, and environments of formation f o r garnets of igneous, r e g i o n a l metamorphic, metasomatic and x e n o c r y s t i c o r i g i n s . ENVIRONMENT OF FORMATION REF. Phenocrysts c r y s t a l l i z e d e a r l y d i r e c t l y from magma ORIGIN GARNET COMP. HOST ROCK Igneous Almandine Pyrope C a l c -a l k a l i n e f e l s i c v o l c a n i c Igneous Spess-a r t i n e Almandine F e l s i c v o l c a n i c / i n t r u s i o n Igneous Spess-a r t i n e Almandine F e l s i c i n t r u s i o n Igneous Spess-a r t i n e Almandine F e l s i c v o l c a n i c / i n t r u s i o n R e g i o n a l meta-morphic Almandine G r o s s u l a r Green-s c h i s t f a c i e s R e g i o n a l meta-morphic Pyrope Almandine Amphib-o l i t e f a c i e s Meta-somatic A n d r a d i t e Spess-a r t i n e Skarns Mn-rich greywacke Xeno-c r y s t i c Meta-morphic High p r e s s u r e phenocrysts c r y s t a l l i z e d a t >7kb and t r a n s p o r t e d t o h i g h e r l e v e l s Low t o moderate p r e s s u r e phenocrysts p r e c i p i t a t e d from peraluminous magmas 3 4 under low f 0 2 or c o n d i t i o n s f H 2 0 Late phase phenocrysts s t a b i l i z e d by h i g h Mn i n d i f f e r e n t i a t e d magmas Po r p h y r o b l a s t s , products of low-grade metamorphism Po r p h y r o b l a s t s , products of high-grade metamorphism P o r p h y r o b l a s t s r e p l a c e m e n t a s s o c i a t e d w i t h a d j a c e n t igneous i n t r u s i o n Xenocrysts d e r i v e d from p a r t i a l l y a s s i m i l a t e d metamorphic rocks 1. Green and Ringwood, 1968 2. Green, 1978 3. M i l l e r and Stoddard, 4. Bartum, 1937 5. M i l l e r and Stoddard, 6. Fodor e t a l . , 1981 7. Deer e t a l . , 1966 8. Deer e t a l . , 1966 9. Zeck, 1970 1981 1978 195 g a r n e t s - a l s o occur i n skarn d e p o s i t s , and i n v e i n s i n metamorphosed, Mn-rich greywacke (Deer e t a l . , 1966). 4.5.2. F i e l d R e l a t i o n s Garnets occur throughout the Capoose r h y o l i t e and comprise 2 t o 5 volume percent of the s i l l s . Other mafic m i n e r a l s , such as b i o t i t e or amphibole are not p r e s e n t . Morphology of the garnet v a r i e s a t d i f f e r e n t l e v e l s i n the s t r a t i g r a p h y . In the lowermost s i l l , quartz garnet r h y o l i t e ( u n i t 6), the garnets are preponderantly i n d i v i d u a l p a l e pink-brown c r y s t a l s 1 t o 2 mm i n diameter ( P l a t e 4.3). Garnet r h y o l i t e ( u n i t 8), the uppermost s i l l , i s t y p i f i e d by dark brown garnet c r y s t a l aggregates 2 t o 5 mm i n diameter ( P l a t e 4.4). 4.5.3 P e t r o g r a p h i c C h a r a c t e r i s t i c s A l l g arnets a t Capoose are g e n e r a l l y anhedral w i t h i r r e g u l a r shapes and f r e q u e n t l y broken c r y s t a l f a c e s ( P l a t e 4.5). Low, abnormal a n i s o t r o p y (0.002 t o 0.003) i s a l s o t y p i c a l ( P l a t e 4.6). No d i s t i n c t i n c l u s i o n t r a i l s are observed w i t h i n the garnets ( P l a t e 4.7); however, s c a t t e r e d i n c l u s i o n s of quartz are common; z i r c o n and a p a t i t e i n c l u s i o n s are r a r e . Garnets occur adjacent t o resorbed quartz phenocrysts up t o 2mm i n diameter ( P l a t e 4.8), and they commonly are intergrown w i t h a myriad of s m a l l e r ( < 1 mm) quartz aggregates ( P l a t e 4.9). Sulphides l o c a l l y f i l l c r a c k s and 196 PLATE 4.3: Photomicrograph o f i n d i v i d u a l p i n k s p e s s a r t i n e i n g a r n e t r h y o l i t e ( u n i t 7; F i g . 4.1), Sample KCP009, Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . PLATE 4.4: Photomicrograph o f aggregates o f brown s p e s s a r t i n e i n r h y o l i t e ( u n i t 8; F i g . 4.1), Sample KCP054, Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . 197 PLATE 4.5: Photomicrograph o f a n h e d r a l brown s p e s s a r t i n e i n r h y o l i t e , Sample KCP044 Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . PLATE 4.6: Photomicrograph o f t y p i c a l s l i g h t l y a n i s o t r o p i c brown s p e s s a r t i n e i n r h y o l i t e , Sample KCP054, Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . 198 PLATE 4.7: Photomicrograph o f brown s p e s s a r t i n e w i t h o u t d i s t i n c t i n c l u s i o n t r a i l s . Garnet r h y o l i t e , Sample KCP012, Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . PLATE 4.8: Photomicrograph o f brown s p e s s a r t i n e a d j a c e n t t o q u a r t z and s u l p h i d e s (opaque) i n g a r n e t r h y o l i t e . Sample KCP012, Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . 199 PLATE 4.9: Photomicrograph o f brown s p e s s a r t i n e a d j a c e n t t o q u a r t z c l u s t e r s i n r h y o l i t e . Sample KCP054, Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . 200 spaces—hetween brown garnets ( P l a t e 4.10). A p h a n i t i c coronas of muscovite and quartz surround garnets, quartz phenocrysts and s u l p h i d e s . T h i s t e x t u r a l evidence i n d i c a t e s the f o l l o w i n g sequence of c r y s t a l l i z a t i o n a t Capoose: (1) garnet d e p o s i t i o n , (2) s u l p h i d e d e p o s i t i o n , and (3) corona development. 4.5.4. Microprobe Compositions 4.5.4.1 a n a l y t i c a l techniques: G r a i n s of garnet were crushed t o a -30 t o +60 mesh s i z e f r a c t i o n i n an agate mortar, hand-picked under a b i n o c u l a r microscope, and washed u l t r a s o n i c a l l y i n d i s t i l l e d water. The garnets were mounted on t r a n s o p t i c ( c l e a r p l e x i g l a s s ) p l u g s t h a t o r i e n t e d the c e n t r e s of each c r y s t a l t o a common plane (technique developed a t The U n i v e r s i t y o f B r i t i s h Columbia). Garnets w i t h i n the plugs were then c u t t o a s e l e c t e d plane, p o l i s h e d and cleaned. Both p i n k and brown garnets from u n i t s 6 t o 8 were analysed on a Cameca SX-50 wavelength d i s p e r s i v e e l e c t r o n microprobe a t The U n i v e r s i t y o f B r i t i s h Columbia (U.B.C.) f o r e i g h t elements: S i , T i , A l , Fe, Mg, Ca, Mn and Na. Runs were made wit h an a c c e l e r a t i n g v o l t a g e of 15 kV, a beam c u r r e n t 0.04 mA, and a 50 um diameter beam. Four primary U.B.C. i n t e r n a l standards were used: (1) garnet (G278) f o r S i and Ca, (2) garnet (G235) f o r A l , Fe and Mg, (3) a c t i n o l i t e (A229) f o r T i and Na, and (4) pyroxene (P245) f o r Mn. Two secondary standards, garnet (G384) and pyroxene (P378)_„ were run c o n c u r r e n t l y with the unknowns. A n a l y t i c a l p r e c i s i o n , based on r e p l i c a t e analyses, i s + 1.0%. Accuracy, based on analyses of i n t e r n a t i o n a l rock standards, i s b e t t e r than + 4.4%. For each garnet unknown s t u d i e d , 10 spots were analysed a t e q u a l l y spaced i n t e r v a l s on a t r a v e r s e from rim t o core. F i v e t o nine g r a i n s were examined i n each of t h r e e specimens (KCP009, KCP012 and KCP054) from u n i t s 6, 7 and 8 r e s p e c t i v e l y . Twenty-two i n d i v i d u a l garnets from Capoose were analysed (Table 4.6). 4.5.4.2 microprobe data Compositions of garnet from twenty-two r i m - t o - t o core t r a v e r s e s are presented i n Table 4.7. T h i s t a b l e s u b d i v i d e s garnets by u n i t and garnet c o l o u r . V a r i a b i l i t y between garnets was t e s t e d i n Tab l e 4.8 by aver a g i n g garnet compositions f o r each t r a v e r s e i n T a b l e 4.7. O v e r a l l , manganese content i s c o n s i s t a n t l y h i g h ( > s p e s s a r t i n e 6 0 ) . Conversely, magnesium v a l u e s are remarkably low ( < p y r o p e 1 # 6 ) . Both brown and pink garnets were analysed f o r each rock type (Table 4.6). C o m p o s i t i o n a l l y , d i f f e r e n c e s between brown and pi n k garnets i s sma l l but i n d i s t i n c t (Table 4.8). By i n s p e c t i o n (Table 4.6) brown garnets are s l i g h t l y r i c h e r i n F e 3 + . Rim-to-core zonation i n elements of each garnet were examined t o e s t a b l i s h t r e n d s and a s s o c i a t i o n s . Zonation t y p i c a l f o r both brown and pi n k garnets from each specimen 202 TABLE"4';'6: Cameca SX-50 wavelength d i s s p e r s i v e e l e c t r o n microprobe analyses of 22 pin k and brown garnets from the Capoose p r o s p e c t . E i g h t elements were determined: S i , T i , A l , Fe, Mg, Ca, Mn and Na. The average o f 10 probe spots f o r "each garnet i s gi v e n . Complete analyses are i n Appendix 3. SAMPLE GARNET Si02 Ti02 A1203 FeO MnO MgO CaO Na20 NO. NO. BROWN GARNETS KCP009 CORE 36. 64 0. 26 21. 03 3 .75 32. 76 0. 13 5. 15 0. 01 RIM5 36. 71 ' o . 09 21. 24 3 .79 33. 00 0. 15 5. 05 0. 01 COR9 34. 39 0. 24 19. 85 3 .57 32. 92 0. 14 5. 21 0. 01 RIM8 35. 43 0. 14 21. 22 3 .32 34. 33 0. 11 3. 71 0. 02 RIM6 35. 58 0. 09 20. 91 3 .44 33. 54 0. 10 5. 10 0. 01 KCP012 RI14 34. 88 0. 23 19. 22 7 .71 32. 79 0. 15 2. 89 o. 01 RI18 34. 20 0. 13 18. 35 7 .08 35. 04 0. 13 2. 66 0. 01 RI23 34. 20 0. 13 18. 35 7 .08 34. 04 0. 10 2. 91 0. 01 RI24 34. 65 0. 18 17. 63 7 .43 34. 52 0. 10 3. 14 0. 01 KCP054 R208 34. 73 0. 38 19. 81 4 .57 37. 30 0. 09 1. 24 0. 01 R210 34. 06 0. 16 18. 41 5 .28 38. 31 0. 10 0. 86 0. 01 R211 35. 01 0. 21 19. 75 4 .84 37. 50 0. 13 0. 75 0. 01 PINK GARNETS KCP009 R216 35. 45 0. 10 20. 46 13 .00 25. 80 0. 39 3 . 05 0. 01 R218 34. 79 0. 20 19. 92 7 .0 30. 82 0. 25 3. 77 0. 01 R220 35. 66 0. 09 20. 92 4 .32 31. 95 0. 17 5. 51 0. 01 R221 35. 91 0. 09 20. 82 3 .30 34. 26 0. 09 4. 62 0. 01 KCP012 RI12 34. 86 0. 26 19. 25 7 .46 32. 83 0. 16 2. 93 0. 01 KCP054 R202 34. 76 0. 14 19. 91 4 .99 36. 93 0. 13 0. 64 0. 01 R203 35. 34 0. 14 19. 84 5 .22 37. 04 0. 14 0. 75 0. 01 R204 35. 10 0. 11 19. 84 4 .57 37. 73 0. 10 0. 76 0. 01 R205 34. 90 0. 11 19. 79 4 .70 37. 89 0. 10 0. 79 0. 01 R206 34. 99 0. 16 19. 72 4 .55 38. 03 0. 13 0. 79 0. 01 203 TABLE 4.7: Average garnet compositions c a l c u l a t e d by e l e c t r o n microprobe analyses o f 22 p i n k and brown garnets from the Capoose p r o s p e c t . Percent change i n endmember composition from rim t o core f o r each garnet i s g i v e n . Sympathetic v a r i a t i o n i n F e 2 + , Mg , C a 2 + , and Mn 2 i s a l s o i n d i c a t e d f o r each garnet t r a v e r s e . SAMPLE GARNET AVERAGE COMPOSITION^ % 2 VARIATION3 NO. NO. SP GR AL PY AD COMPOSITION BROWN < SARNETS KCP009 CORE 76 14 9 0.5 0.5 1.2 Fe/Ca RIM5 76 14 9 0.6 0.1 0.05 Fe/Mn C0R9 76 13 8 0.6 2.0 0.06 Mn/Ca RIM8 81 11 8 0.5 0.3 0.1 Mn/Ca RIM6 77 15 8 0.4 0.2 1.4 -KCP012 RI14 74 3 17 0.6 5 0.2 Ca/Mn RI18 79 3 13 0.5 5 2.1 • Fe/Mn RI23 75 0 16 0.4 9 0.8 Fe/Mn RI24 73 0 15 0.4 12 4.1 Ca/Mn KCP054 R208 86 1 10 0.4 2 2.0 Ca/Mg R210 80 0 11 0.4 8 0.04 Ca/Mg Fe/Mn R211 86 0.2 11 0.5 3 2.6 Ca/Mg PINK GARNETS KCP009 R216 60 '9 30 1.6 0.2 5.7 Ca/Mn R218 72 9 16 0.8 2.0 13.3 Ca/Mn R220 - 74 16 10 0.7 0.2 3.0 -R221 79 13 7 0.4 0.2 0.5 Fe/Ca KCP012 RI12 75 3 17 0.6 5 3.3 -KCP054 R202 86 0.1 11 0.5 2 1.9 Ca/Mg R203 85 0.4 12 0.6 2.5 2.8 Ca/Mg R204 87 0.2 10 0.4 2.5 0.6 Ca/Mg R205 86 0 10 0.4 3 0.7 Ca/Mg R206 86 0 10 0.5 3 2.2 Ca/Mg Fe/Mn 1. Average composition a b b r e v i a t i o n s : SP = s p e s s a r t i n e , GR = g r o s s u l a r i t e , AL = almandite, PY = pyrope, AD = a n d r a d i t e . 2. Percent change i n endmember composition from r i m - t o - c o r e . 3. Sympathetic element v a r i a t i o n . 204 TABLE 4.8: D i s t i n c t i o n i n composition between brown and pink g a r n e t s . Capoose prospect, d e f i n e d by the F - t e s t . SOURCES OP VARIATION DEGREES OF FREEDOM SUMS OF SQUARES SSQ MEAN SQUARE MSQ F c a l c 1 s p e s s a r t i n e average composition 1 3.0 866.0 0.01 g r o s s u l a r i t e average composition 1 6.9 40.4 0.17 almandite average composition 1 26.0 25.0 1. 04 pyrope average composition 1 1.8 20.0 3.12 a n d r a d i t e average composition 1 22.0 8.9 2 .47 1. F( l , 2 0 ) f o r = 0.05 = 4.35 205 i s graphed i n F i g u r e 4.12. L o c a l i r r e g u l a r i t i e s i n p l o t t e d t r a v e r s e s were caused by i n c l u s i o n s w i t h i n the ga r n e t s . Garnets from Capoose have some common zo n a t i o n f e a t u r e s . Most garnets show <5% change i n end member composition from rim t o core ( F i g . 4.12). A l l garnets have c a l c i u m - r i c h cores and calcium-poor rims. Zonation i n pink and brown garnets i s d i s t i n c t i v e . P a t t e r n s i n manganese zonat i o n between pi n k and brown garnets are re v e r s e d . Cores of pink garnets are Mn-e n r i c h e d , whereas rims of brown garnets are Mn-enriched. I r o n z o n a t i o n i s g e n e r a l l y i r r e g u l a r , but some p i n k garnets show i r o n enrichment i n the rims. Rim t o core z o n a t i o n i n garnets of the same c o l o u r , even from d i f f e r e n t u n i t s , i s c o n s i s t e n t and c h a r a c t e r i s t i c . Brown garnets from quartz garnet r h y o l i t e ( F i g . 4.1: u n i t 6: KCP009) and garnet r h y o l i t e ( F i g . 4.1: u n i t 7: KCP012) show sympathetic i r o n and manganese p a t t e r n s ( F i g . 4.12A and B). Brown garnets of the r h y o l i t e ( F i g . 4.1: u n i t 8: KCP054) show sympathetic c a l c i u m and mangesium c o v a r i a t i o n ( F i g . 4.12C). Conversely, pink garnets of quartz garnet r h y o l i t e ( u n i t s 6) and r h y o l i t e ( u n i t 8) vary s y m p a t h e t i c a l l y i n c a l c i u m and manganese ( F i g . 4.12D and E ) . Pink garnets from garnet r h y o l i t e ( u n i t 7) show an i n v e r s e r e l a t i o n s h i p between i r o n and manganese enrichment but a sympathetic r e l a t i o n s h i p between i r o n and c a l c i u m ( F i g . 4.12F). 4.5.5 Oxygen Isotope Compositions 206 2.0 1.5-— I 33.0 -I 1 i . 1 1 1 1 , c o r e rim c o r a Line graphs dep i c t i n g calcium, magnesium, ir o n and manganese compositional zoning from rim-to-core i n three brown garnet and three pink garnet grains fron units 6, 7, and 8 (Fig. 4.1, Table 4.7). Sympathetic v a r i a t i o n i n manganese and ir o n d i f f e r s from calciuin and magnesium v a r i a t i o n . Zonation i n pink and brown garnets i s d i s t i n c t i v e (section 4.5.4.2).Vertical b a r are standard deviations of analyses. A) KCP009-RIM5 brown, B) KCP012-RI18 brown, C) KCP054-R208 brown, D) KCP009-R218 pink, E) KCP012-RI12 pink, F) K C P 0 5 4 -R202 pink. 207 FIGURE 4.12: L i n e graphs d e p i c t i n g calcium, magnesium, i r o n and manganese c o m p o s i t i o n a l zoning from r i m - t o - c o r e i n t h r e e brown garnet and t h r e e p i n k g a r n e t g r a i n s from u n i t s 6, 7, and 8 ( F i g . 4.1, T a b l e 4.7). Sympathetic v a r i a t i o n i n manganese and i r o n d i f f e r s from c a l c i u m and magnesium v a r i a t i o n . Zonation i n p i n k and brown garnets i s d i s t i n c t i v e ( s e c t i o n 4 . 5 . 4 . 2 ) . V e r t i c a l bars are standard d e v i a t i o n s of a n a l y s e s . A) KCP009-RIM6 brown, B) KCP012-RI18 brown, C) KCP054-R208 brown, D) KCP009-R218 pink, E) KCP012-RI12 pink , F) KCP054 -R202 pink. 208 * o a o 0.0 rim 2.0 i o a 2 rim FIGURE 4.12: Line graphs d e p i c t i n g calcium, magnesium, iron and manganese compositional zoning from rim-to-core i n three brown garnet and three pink garnet grains from units 6 , 7 , and 8 (Fig. 4 . 1 , Table 4 . 7 ) . Sympathetic v a r i a t i o n i n manganese and i r o n d i f f e r s from calcium and magnesium v a r i a t i o n . Zonation i n pink and brown garnets i s d i s t i n c t i v e (section 4 . 5 . 4 . 2 ) . V e r t i c a l bars are standard deviations of analyses. A) KCP009-RIM6 brown, B) KCP012-RI18 brown, C) KCP054-R208 brown, D) KCP009-R218 pink, E) KCP012-RI12 pink, F) KCP054 -R202 pink. 209 FIGURE 4.12: L i n e graphs d e p i c t i n g c a l c i u m , magnesium, i r o n and manganese c o m p o s i t i o n a l z o n i n g from r i m - t o - c o r e i n t h r e e brown g a r n e t and t h r e e p i n k g a r n e t g r a i n s from u n i t s 6, 7, and 8 ( F i g . 4.1, T a b l e 4.7). Sympathetic v a r i a t i o n i n manganese and i r o n d i f f e r s from c a l c i u m and magnesium v a r i a t i o n . Z o n a t i o n i n p i n k and brown g a r n e t s i s d i s t i n c t i v e ( s e c t i o n 4 . 5 . 4 . 2 ) . V e r t i c a l bars are s t a n d a r d d e v i a t i o n s of a n a l y s e s . A) KCP009-RIM6 brown, B) KCP012-RI18 brown, C) KCP054-R208 brown, D) KCP009-R218 p i n k , E) KCP012-RI12 p i n k , F) KCP054 -R202 pi n k . 210 FIGURE 4.12: L i n e graphs d e p i c t i n g c a l c i u m , magnesium, i r o n and manganese c o m p o s i t i o n a l zoning from r i m - t o - c o r e i n t h r e e brown g a r n e t and t h r e e p i n k g a r n e t g r a i n s from u n i t s 6, 7, and 8 ( F i g . 4.1, T a b l e 4.7). Sympathetic v a r i a t i o n i n manganese and i r o n d i f f e r s from c a l c i u m and magnesium v a r i a t i o n . Z o n a t i o n i n p i n k and brown ga r n e t s i s d i s t i n c t i v e ( s e c t i o n 4 . 5 . 4 . 2 ) . V e r t i c a l bars are s t a n d a r d d e v i a t i o n s of a n a l y s e s . A) KCP009-RIM6 brown, B) KCP012-RI18 brown, C) KCP054-R208 brown, D) KCP009-R218 pink , E) KCP012-RI12 p i n k , F) KCP054 -R202 pi n k . 211 2.0 FIGURE 4.12: L i n e graphs d e p i c t i n g c a l c i u m , magnesium, i r o n and manganese c o m p o s i t i o n a l zoning from r i m - t o - c o r e i n t h r e e brown garnet and t h r e e p i n k g a r n e t g r a i n s from u n i t s 6, 7, and 8 ( F i g . 4.1, T a b l e 4.7). Sympathetic v a r i a t i o n i n manganese and i r o n d i f f e r s from c a l c i u m and magnesium v a r i a t i o n . Z o n a t i o n i n p i n k and brown gar n e t s i s d i s t i n c t i v e ( s e c t i o n 4 . 5 . 4 . 2 ) . V e r t i c a l bars are standard d e v i a t i o n s o f a n a l y s e s . A) KCP009-RIM6 brown, B) KCP012-RI18 brown, C) KCP054-R208 brown, D) KCP009-R218 pink, E) KCP012-RI12 p i n k , F) KCP054 -R202 p i n k . 212 Oxygen i s o t o p e compositions of quartz and garnet m i n e r a l separates from r h y o l i t e s i l l s a t Capoose were determined u s i n g standard s t a b l e i s o t o p e t e c h n i q u e s ( s e c t i o n 4.7). Seven m i n e r a l separates were analysed; sample l o c a t i o n s and oxygen i s o t o p i c compositions a re i n F i g u r e 4.23 and Table 4.15. Quartz and garnet r e t a i n the o r i g i n a l i s o t o p i c composition of the magma whereas whole rock v a l u e s might r e f l e c t the composition of f l u i d s t h a t have passed through the rock (Kyser, 1986). Therefore, the temperature o f formation o f the f e l s i c magma which formed s i l l s a t Capoose can be c a l c u l a t e d g i v e n the oxygen i s o t o p e compositions o f quartz and garnet m i n e r a l separates. The o r i g i n of garnet can be f u r t h e r c o n s t r a i n e d g i v e n i t s temperature o f formation. Magmatic garnets i n c o a r s e - g r a i n e d f e l s i c igneous rocks occur a t temperatures between 480°C-620°C and i n f i n e - g r a i n e d f e l s i c igneous rocks between 670°C and 1000°C ( B o t t i n g a and Javoy, 1975; Carmichael, 1974). Metamorphic garnets have lower temperatures o f form a t i o n from 400°C up t o 480°C i n g r e e n s c h i s t f a c i e s t e r r a n e s and 480°C up t o 550°C i n amphibolite f a c i e s t e r r a n e s ( B o t t i n g a and Javoy, 1975). C a l c u l a t i o n o f a temperature o f formation u s i n g q u a r t z -garnet p a i r s f o l l o w s the procedure o f B o t t i n g a and Javoy (1975). Using the va l u e s i n Table 4.15 and assuming i s o t o p i c e q u i l i b r i u m between quartz and garnet p a i r s , the (Q,G) f o r each sample i s c a l c u l a t e d (Table 4.15). S i n c e 213 quartz—(X) and garnet (Y) are nonhydrous s i l i c a t e s and assuming T>500°C; then B ^ Q ^ i s d e r i v e d as f o l l o w s : Equation 4.1. QUARTZ-GARNET (Bot t i n g a and Javoy, 1975): 10001na(X,Y) = B x y / T 2 i s approximately equal t o A(X,Y) A(Q,G) = 2.9 (1000/T) 2, and T 2 = 2.9(10 6)/A(Q,G). Thus from equation 4.1: b ( Q G) = 2 ' 9 ( i ° 6 ) Using equation 4.1, temperatures of 528°C t o 677°C (+ 7°C) were c a l c u l a t e d f o r quartz and brown garnet p a i r s and a temperature o f 725°C + 7°C was c a l c u l a t e d f o r quartz and pink garnet (Table 4. 9). Temperatures of formation of 528°C t o 725°C suggest t h a t the garnets are magmatic i n o r i g i n . Thus these temperatures r e p r e s e n t c l o s e l y the expected igneous temperature of formation (see above) f o r the magma forming r h y o l i t e s i l l s a t Capoose. 4.5.6 D i s c u s s i o n Garnets i n r h y o l i t e s i l l s on Fawnie Range c o u l d have formed as: (1) h i g h pressure phenocrysts which c r y s t a l l i z e d at depth (P > 7 kb: Green, 1978) and s u r v i v e d t r a n s p o r t t o hi g h e r c r u s t a l l e v e l s , (2) low t o moderate p r e s s u r e phenocrysts p r e c i p i t a t e d from d i f f e r e n t i a t e d peraluminous magmas under low f Q 2 or f ^ o c o n d ; L t ; L o n s ( M i l l e r and Stoddard, 1981), (3) l a t e phase phenocrysts s t a b i l i z e d by hi g h Mn i n d i f f e r e n t i a t e d magmas, (4) prod u c t s o f low-grade 214 C a l c u l a t i o n of a minimum igneous temperature of formation from garnet and quartz c r y s t a l s i n r h y o l i t e s , Capoose p r o p e r t y , c e n t r a l B r i t i s h Columbia ( s e c t i o n 4.5). Sample l o c a t i o n s are i n F i g u r e 4.4. SAMPLE NO. d ^ O 1 QUARTZ d^O 1 GARNET Q/G T(K) T(°C) KCP009 8.1 5.2 2.9 998 725 KCP009 8.1 4.6 3.5 909 636 KCP012 8.0 4.8 3.2 950 677 KCP054 8.4 3.9 4.5 801 528 AVERAGE: 915 + 73 642 + 73 1. A l l s t a b l e i s o t o p e analyses were done i n the l a b o r a t o r y of T.K. Kyser, Department of 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 Saskatchewan. TABLE 4.9: 1 215 metamorphism, or (5) r e s i d u a l phases of a h i g h grade metamorphic t e r r a n e . P e t r o g r a p h i c a l l y , two types of garnet are d i s t i n g u i s h e d at Capoose: (1) a p i n k garnet which occurs as i n d i v i d u a l c r y s t a l s , and (2) a brown garnet which commonly forms c r y s t a l aggregates. The anhedral nature of the g a r n e t s c o u l d be the r e s u l t of chemical r e a c t i o n and/or mechanical b r e a k i n g . I n t r u s i o n of the s i l l s c o u l d have been h i g h enough i n the c r u s t so t h a t the low p r e s s u r e caused the margins of the garnet t o r e a c t with the melt. S p e c i f i c a l l y , anhedral g r a i n s and coronas of muscovite and quartz around garnets c o u l d r e f l e c t such r e a c t i o n s . Buddington (1939) suggested t h a t coronas, i n g e n e r a l , can be produced by l a t e magmatic processes r e l a t e d t o d i s c o n t i n u o u s r e a c t i o n of e a r l y formed c r y s t a l s out of e q u i l i b r i u m w i t h a l a t e r melt. With t h i s i n mind, i t i s i n t e r e s t i n g t o note t h a t garnet i s the o n l y mafic m i n e r a l . I f b i o t i t e was an e a r l y p h e n o c r y s t i c phase, the f o l l o w i n g r e a c t i o n c o u l d have c o n t r o l l e d garnet paragenesis: ( b i o t i t e ) + (MnO, A 1 2 0 3 , S i 0 2 ) from l i q u i d • (garnet + muscovite + quartz) The above r e a c t i o n c o u l d e x p l a i n the absence of b i o t i t e , and the garnet, muscovite and quartz assemblage. C o m p o s i t i o n a l l y , Capoose garnets are among the most s p e s s a r t i n e r i c h garnets r e p o r t e d i n the l i t e r a t u r e ( M i l l e r and Stoddard, 1981; Troger, 1959). T h e i r presence i n r h y o l i t e s i l l s matches t y p i c a l occurrences o f s p e s s a r t i n e -almandine phenocrysts i n f e l s i c i n t r u s i v e s . Pink and brown garnets r e p r e s e n t c o m p o s i t i o n a l l y s i m i l a r p o p u l a t i o n s (Table 4.8). The dark brown c o l o u r of some garnets i s a t t r i b u t e d t o a r e l a t i v e l y h i g h i r o n content with r e s p e c t t o p i n k garnets. Compositions of Capoose garnets are expressed as the end members: AL (almandine) + PY (pyrope), SP ( s p e s s a r t i n e ) , and GR ( g r o s s u l a r i t e ) + AN (andradite) i n F i g u r e 4.13. On t h i s diagram garnet compositions are compared f o r the f o l l o w i n g environments: plutonic (Troger, 1959; Vennum and Meyer, 1979), volcanic (Bryant, 1975; F i t t o n , 1972; Green and Ringwood, 1968; O l i v e r , 1956; Troger, 1959; Wood, 1974), greenschist (Brown, 1967; 1969; Fodor e t a l . , 1979; Troger, 1959), and amphibolite (Miyashiro, 1953; Troger, 1959). A l l Capoose garnets are low i n CaO (<16 mole% g r o s s u l a r + a n d r a d i t e ) , which d i s t i n g u i s h e s them from the g r e e n s c h i s t -f a c i e s metamorphic garnets, and h i g h i n MnO (>60% s p e s s a r t i n e ) , which separates them from h i g h e r grade metamorphic garnets and v o l c a n i c g a r n e t s . Although composition s e r v e s as one method of d i s t i n g u i s h i n g g a r n e t s , a n a l y s i s o f zoning p a t t e r n s , below, are a l s o used. Zoning p a t t e r n s help t o d e f i n e the o r i g i n o f ga r n e t s a t Capoose. Both p i n k and brown garnets show <5% change i n end member composition from rim to core. T h i s weak z o n a t i o n i s c h a r a c t e r i s t i c o f igneous garnets (Bryant, 1975), but not d i a g n o s t i c . Al + Py Plutonic Volcanic Greenschist Amphi bol Ite Capoose Garnets Gr + An O A 4.13: Compositions of Capoose g a r n e t s , expressed as the end members: AL (almandine) + PY (pyrope), SP ( s p e s s a r t i n e ) , and GR ( g r o s s u l a r i t e ) + AN ( a n d r a d i t e ) , are compared with the f o l l o w i n g environments: p l u t o n i c (Troger, 1959; Vennum and Meyer, 1979), v o l c a n i c (Bryant, 1975; F i t t o n , 1972; Green and Ringwood, 1968; O l i v e r , 1956; Troger, 1959; Wood, 1974), g r e e n s c h i s t (Brown, 1969; Fodor and Burt, 1979; Troger, 1959), and a m p h i b o l i t e (Miyashiro, 1953; Troger, 1959). Capoose garnets are s i m i l a r o n l y t o S P - r i c h p l u t o n i c garnets. 218 Brown garnets t y p i c a l l y have Mn-rich rims, a z o n a t i o n t y p i c a l f o r igneous garnets (Green, 1977). T h i s s p e s s a r t i n e i n c r e a s e from core t o rim co u l d be d i r e c t l y r e l a t e d t o p r o g r e s s i v e enrichment of MnO from c r y s t a l f r a c t i o n a t i o n ( M i l l e r and Stoddard, 1981); because, a p a r t from garnet, manganese i s not a p r i n c i p a l c o n s t i t u e n t o f igneous s i l i c a t e s . Thus, c r y s t a l f r a c t i o n a t i o n i s a p l a u s i b l e mechanism t o e x p l a i n Mn-zonation i n brown g a r n e t s . Pink garnets w i t h Mn-rich cores are s i m i l a r i n zoning t o metamorphic garnets i n the g r e e n s c h i s t f a c i e s (Brown, 1969). The zoning i n these metamorphic g a r n e t s has been a t t r i b u t e d t o steady d e p l e t i o n i n MnO d u r i n g garnet growth and e x p l a i n e d by a model based on R a y l e i g h f r a c t i o n a t i o n ( H o l l i s t e r , 1966). Zoning i n brown garnets i n v o l v e s sympathetic v a r i a t i o n of Fe and Mn as one group and sympathetic v a r i a t i o n o f Ca and Mg as another ( F i g s . 4.12A, B and C). Such c o r r e l a t i o n s are c h a r a c t e r i s t i c f o r garnets from igneous r o c k s (Bryant, 1975). Conversely, pink garnets e x h i b i t 'normal' zoning as Fe and Mg va r y s y m p a t h e t i c a l l y as one group and Ca and Mn var y s y m p a t h e t i c a l l y as another ( F i g s . 4.12D, E and F ) . T h i s z o n a t i o n has been noted i n garnets formed i n r e g i o n a l g r e e n s c h i s t metamorphic f a c i e s (Evans, 1965; Leake, 1968; Okrusch, 1971). Zoning p a t t e r n s w i t h i n brown and p i n k garnet types emphasise the e x i s t a n c e of two sep a r a t e p o p u l a t i o n s of garnet. 219 An igneous o r i g i n f o r dark brown garnets i n r h y o l i t e s i l l s on Fawnie Range i s supported by p e t r o g r a p h i c , chemical and i s o t o p i c evidence. These garnet aggregates occur as s p e s s a r t i n e - r i c h , g r o s s u l a r - p o o r , weakly zoned phenocrysts w i t h zoning p a t t e r n s t y p i c a l f o r igneous g a r n e t s . Moreover, they formed a t magmatic temperatures of 528°C t o 677°C + 7°C. Evidence f o r a d e f i n i t i v e o r i g i n of the p i n k garnets a t Capoose based on zoning p a t t e r n s i s l e s s c l e a r . I n d i v i d u a l p i n k garnet c r y s t a l s are t e x t u r a l l y and c o m p o s i t i o n a l l y of igneous o r i g i n ; they e x h i b i t weak z o n a t i o n t y p i c a l f o r igneous g a r n e t s ; however, t h e i r zoning p a t t e r n s are t y p i c a l of garnets c r y s t a l l i z e d d u r i n g prograde metamorphism. The p i n k garnets c o u l d have been primary phases i n the r h y o l i t e s i l l s t h a t subsequently underwent r e t r o g r a d e metamorphism. Breakdown of p i n k garnet near i t s rims may have r e s u l t e d i n the low Mn rim v a l u e s recorded by the e l e c t r o n microprobe i n t h i s study. With t h i s i n mind, an igneous o r i g i n i s a l s o proposed f o r p i n k garnets a t Capoose. Oxygen i s o t o p e compositions c o n f i r m t h a t these garnets formed a t a magmatic temperature of 725°C + 7°C. These garnet phenocrysts occur as s p e s s a r t i n e - r i c h , g r o s s u l a r - p o o r , weakly zoned phenocrysts which c r y s t a l l i z e d from a melt under e q u i l i b r i u m c o n d i t i o n s . They l a t e r became u n s t a b l e i n t h e i r subsequent environment and coronas were formed. The occurrence of igneous garnets a t Capoose i s unusual and thus important i n understanding the p e t r o g e n e s i s of 220 r h y o l i t e s i l l s on Fawnie Range. T h i s i n t u r n has p o t e n t i a l t e c t o n i c i m p l i c a t i o n s . Compositions of Capoose garnets p l o t i n the same f i e l d s as t y p i c a l garnets of g r a n i t o i d s c r y s t a l l i z e d from h i g h Mn/(Fe + Mg) environments ( F i g . 4.13). Experimental s t u d i e s show t h a t h i g h Mn enhances s t a b i l i t y o f garnet i n magmas, a l l o w i n g i t t o c r y s t a l l i z e as a primary igneous mineral a t press u r e s o f 3 kb o r l e s s (Hsu, 1968; Green, 1978). T h e i r c o m p o s i t i o n a l and experimental data were i n t e r p r e t e d as showing t h a t most ga r n e t s i n g r a n i t i c rocks p r e c i p i t a t e d i n response t o h i g h Mn r e l a t i v e t o Fe and Mg ( M i l l e r and Stoddard, 1981). These o b s e r v a t i o n s support the hypothesis (3), above, t h a t g arnets at Capoose c r y s t a l l i z e d as l a t e phase phenocrysts s t a b i l i z e d by h i g h Mn i n a d i f f e r e n t i a t e d magma. D e p o s i t i o n of garnets a t Capoose as l a t e phase phenocrysts under p r e s s u r e s of 3 kb or l e s s corresponds t o depths of l e s s than a k i l o m e t r e . By example, such depths are p l a u s i b l e f o r f e l s i c magmatism i n the study a r e a ; the v o l c a n i c s o f the Skeena Arch n o r t h of Capoose are thought t o be u n d e r l a i n by g r a n i t i c rocks a t depths o f up t o 3 km (Stacey, 1976). Magmatic temperatures of fo r m a t i o n of 528°C to 725°C are c o n s i s t a n t w i t h P/T c o n d i t i o n s suggested above. The Capoose b a t h o l i t h , a l a r g e i n t r u s i v e body 5 km northwest o f the map area i s a p o t e n t i a l p arent magma f o r r h y o l i t e s i l l s a t Capoose. Composition o f the b a t h o l i t h i s conducive t o the occurrence of garnet because i t i s metaluminous (Appendix IB), A 1 2 0 3 > (Na 20 + K 2Q), e n a b l i n g excess aluminum t o enhance the garnet s t a b i l i t y . Furthermore, the s i l l s and b a t h o l i t h are c o e v a l ( s e c t i o n 4.4). However, the whole rock composition o f the b a t h o l i t h (Appendix IB) i s not e n r i c h e d i n manganese (MnO = 0.06 wt.%) to the extent i t i s i n the s i l l s (MnO > 1 wt.%). D e s p i t e such a d i f f e r e n c e i n Mn component, i f the g a r n e t s c r y s t a l l i z e d as l a t e phase phenocrysts s t a b i l i z e d by h i g h Mn i n s i l l s from the same d i f f e r e n t i a t e d magma t h a t formed the Capoose b a t h o l i t h , one would expect the s i l l s t o be e n r i c h e d i n Mn r e l a t i v e t o the o v e r a l l composition o f the c r y s t a l l i z i n g magma. 4.6 MINERALIZATION AND ALTERATION The Capoose prospect i s a low-grade, b u l k mineable-type s i l v e r - l e a d - z i n c d e p o s i t with minor g o l d p o t e n t i a l . Three zones of p r e c i o u s and base metal m i n e r a l i z a t i o n have been i d e n t i f i e d on the p r o p e r t y (Schroeter, 1981); two are hosted by g a r n e t i f e r o u s r h y o l i t e ( u n i t 8, F i g . 4.14), the t h i r d by h o r n f e l s e d a r g i l l i t e ( u n i t 4, F i g . 4.14). These zones are c o i n c i d e n t w i t h a broad s i l v e r l i t h o g e o c h e m i c a l anomaly d e l i n e a t e d by Church and Diakow (1982), and l o c a l l y h i g h l e a d anomalies d i s c o v e r e d by Rio T i n t o Canadian E x p l o r a t i o n L t d . i n 1970. The bes t i n t e r s e c t i o n s i n d r i l l c o r e a r e : 126 m gr a d i n g 0.38 g per tonne g o l d and 55.1 g per tonne s i l v e r i n zone 1; and 99 m grad i n g 0.25 g per tonne g o l d and 51.3 g per tonne s i l v e r i n zone 2. I n t e r c e p t s a re co r e l e n g t h s , not n e c e s s a r i l y t r u e widths. D e t a i l e d d e s c r i p t i o n o f the nature and occurrence o f m i n e r a l i z e d zones t o g e t h e r w i t h 222 FIGURE 4.14: M i n e r a l i z e d zones of the Capoose P r o s p e c t , Capoose Lake area, c e n t r a l B r i t i s h Columbia. 223 d i s t r i b u t i o n of ore minerals and s t a t i s t i c a l a n a l y s e s of metals f o l l o w . 4.6.1. DESCRIPTION OF ZONES Surface samples and core from zones 1 and 2 hosted i n r h y o l i t e were examined i n d e t a i l i n 1986. Zone 3 w i t h i n h o r n f e l s e d a r g i l l i t e was not con s i d e r e d . Diamond d r i l l core from h o l e s 8, 17, 24, 31, 34, 40, 44 and 57 ( F i g . 4.14) was logged i n d e t a i l . V e r t i c a l c r o s s s e c t i o n s were developed u s i n g the GEOLOG system (name r e g i s t e r e d by I n t e r n a t i o n a l Geosystems C o r p o r a t i o n , Vancouver, B.C.). S e l e c t e d samples from h o l e s 4, 5, 6 and 9, pro v i d e d by T.G. S c h r o e t e r and D.V. Lefebure both o f the B.C.M.E.M.P.R., were reviewed t o supplement the study. M i n e r a l i z e d zones hosted i n r h y o l i t e a t Capoose are t y p i f i e d by p y r i t e , s p h a l e r i t e , galena, c h a l c o p y r i t e and a r s e n o p y r i t e o c c u r r i n g mainly as d i s s e m i n a t i o n s and sometimes as m i n e r a l aggregates or v e i n l e t s . F r e q u e n t l y , anhedral brown garnet occurs i n c l o s e a s s o c i a t i o n w i t h the s u l p h i d e aggregates. Pink garnet has not been observed adjacent t o s u l p h i d e s . Development of f i n e g r a i n e d muscovite and quartz coronas up t o 5 mm i n width around these s u l p h i d e and garnet accumulations i s common. T e t r a h e d r i t e , p y r r h o t i t e , p y r a r g y r i t e , electrum, n a t i v e g o l d and c u b a n i t e have been observed as i n c l u s i o n s w i t h i n the dominant s u l p h i d e s by Granges E x p l o r a t i o n L t d . (Schroeter, 1981). 224 D i s t r i b u t i o n of s u l p h i d e s and garnet from zones 1 and 2 i s i l l u s t r a t e d by v e r t i c a l s e c t i o n ( F i g . 4.15). The s e c t i o n s are hand contoured t o d e f i n e the f o l l o w i n g amounts of garnet and s u l p h i d e s : (1) l e s s than 0.1%, (2) between 0.1 and 1%, (3) between 1 and 5%, and (3) g r e a t e r than 5%. The f o l l o w i n g s u l p h i d e d i s t r i b u t i o n s o v e r l a p i n zone 1: ( l ) p y r i t e and a r s e n o p y r i t e , (2) c h a l c o p y r i t e and s p h a l e r i t e , and (3) s p h a l e r i t e , galena, and p y r i t e . P y r i t e , a r s e n o p y r i t e , c h a l c o p y r i t e and galena o v e r l a p i n zone 2. Much of the r h y o l i t e has been p e r v a s i v e l y s e r i c i t i z e d . The i n t e n s i t y of p h y l l i c a l t e r a t i o n has been mapped q u a l i t a t i v e l y and i s shown i n F i g u r e 4.16. Zones o f h i g h or in t e n s e p h y l l i c a l t e r a t i o n g e n e r a l l y correspond w i t h m i n e r a l i z e d zones d e f i n e d above. A r g i l l i t e and l i t h i c wacke ( u n i t s 4 and 5: F i g u r e 4.1) have been h o r n f e l s e d by i n t r u s i o n o f the r h y o l i t e s i l l s . The l i m i t of h o r n f e l s i c a l t e r a t i o n i s estimated i n F i g u r e 4.16. E x t e n s i v e hydrothermal v e i n i n g i s n o t a b l y absent w i t h i n the g a r n e t i f e r o u s r h y o l i t e s i l l s a t Capoose. Rare v e i n s of quartz and c a l c i t e l e s s than 1 cm t h i c k occur i n l i t h i c wacke ( u n i t 5). These v e i n s are barren o f s u l p h i d e s f o r the most p a r t although p y r i t e occurs as l o c a l d i s s e m i n a t i o n s i n the v e i n s . The v e i n s a l s o show open space f i l l i n g t e x t u r e s such as cockade and drusy quartz. 4.6.2. ORE PETROLOGY s w SPHALERITE NE DDH 040 DDH 017 DDH 034 DDH 031 DDH 024 DDH 008 m 1750 DDH 05 ZONE 2 ZONE 1 100 metres 200 B B' FIGURE 4.15: a) Southwest-northeast v e r t i c a l s e c t i o n ( B - B 7 : F i g . 4.1 of t h e Capoose p r o s p e c t showing d i s t r i b u t i o n from zone 1 and 2 ( F i g 4.14) o f A) s p h a l e r i t e , B) galena, C) a r s e n o p y r i t e , D) c h a l c o p y r i t e , and E) p y r i t e w i t h depth. R e f e r t o F i g u r e 4.3 f o r g e o l o g y . M Ul s w GALENA NE DDH 040 DDH 017 DDH 034 DDH 031 DDH 024 DDH 008 DDH 05 ZONE 2 ZONE 1 100 200 metres B B' FIGURE 4.15: a) South w e s t - n o r t h e a s t v e r t i c a l s e c t i o n ( B - B 7 : F i g . 4.1 o f t h e Capoose p r o s p e c t showing d i s t r i b u t i o n from zone 1 and 2 ( F i g 4.14) o f A) s p h a l e r i t e , B) g a l e n a , C) a r s e n o p y r i t e , D) c h a l c o p y r i t e , and E) p y r i t e w i t h depth. R e f e r t o F i g u r e 4.3 f o r geol o g y . to s w o 1750 a CO i 1 550 ARSENOPYRITE NE DDH 040 DDH 0 DDH 034 DDH 03 1 DDH 024 DDH 008 DDH 05 ZONE 2 ZONE 1 >5% 0 100 200 metres B B' FIGURE 4.15: a) Southwest-northeast v e r t i c a l s e c t i o n (B-B':Fig. 4.1 of t h e Capoose p r o s p e c t showing d i s t r i b u t i o n from zone 1 and 2 ( F i g 4.14) o f A) s p h a l e r i t e , B) g a l e n a , C) a r s e n o p y r i t e , D) c h a l c o p y r i t e , and E) p y r i t e w i t h depth. R e f e r t o F i g u r e 4.3 f o r ge o l o g y . to to s w CHALCOPYRITE NE DDH 040 DDH 017 DDH 034 DDH 031 DDH 024 DDH 008 a a m I 1650 .o (0 a o I 1 550 DDH 05 ZONE 2 ZONE 1 100 200 metres B B' FIGURE 4.15: a) Southwest-northeast v e r t i c a l s e c t i o n (B-B':Fig. 4.1 of t h e Capoose p r o s p e c t showing d i s t r i b u t i o n from zone 1 and 2 ( F i g 4.14) of A) s p h a l e r i t e , B) galena, C) a r s e n o p y r i t e , D) c h a l c o p y r i t e , and E) p y r i t e w i t h depth. R e f e r t o F i g u r e 4.3 f o r geology. to to CO SW PYRITE NE DDH 040 DDH 01 DDH 034 DDH 03 1 DDH 024 DDH 008 DDH 05 o 1750 > a a e n > 1850 a to n o 2 1 550 ZONE 2 ZONE 1 0 100 200 metres B B' FIGURE 4.15 a) Southwest-northeast v e r t i c a l s e c t i o n (B-B':Fig. 4.1 of t h e Capoose p r o s p e c t showing d i s t r i b u t i o n from zone 1 and 2 ( F i g 4.14) o f A) s p h a l e r i t e , B) galena, C) a r s e n o p y r i t e , D) c h a l c o p y r i t e , and E) p y r i t e w i t h depth. R e f e r t o F i g u r e 4.3 f o r geology. to 2 3 0 FIGURE 4.16: Q u a l i t a t i v e a l t e r a t i o n map of the Capoose prospect. Zones of p h y l l i c a l t e r a t i o n a re i n d i c a t e d by hatched l i n e s ; extreme p h y l l i c a l t e r a t i o n i s i n d i c a t e d by c r o s s h a t c h i n g . Sphalerite (ZnS), the most prominant ore m i n e r a l , i s d i s t r i b u t e d unevenly throughout the zones ( F i g . 4.15). I t occurs as anhedral aggregates l e s s than 1 mm i n diameter. Fr e q u e n t l y , p y r i t e and c h a l c o p y r i t e form e x s o l u t i o n s i n s p h a l e r i t e . A r s e n o p y r i t e (FeAsS), c h a l c o p y r i t e ( C u 5 F e S 4 ) , and t r a c e p y r a r g y r i t e (Ag 3SbS) form i n c l u s i o n s w i t h i n s p h a l e r i t e ( P l a t e 4.11). C o v e l l i t e (CuS) occurs as t h i n f i l m s on s p h a l e r i t e ( P l a t e 4.12). Galena (PbS), the second most prominant ore m i n e r a l , i s a l s o unevenly d i s t r i b u t e d throughout the zones ( F i g . 4.15). T y p i c a l l y f r a c t u r e d , i t occurs as anhedral aggregates or 'blebs' up t o 1 cm i n diameter i n s u l p h i d e v e i n l e t s ( P l a t e 4.13) and as f i n e g r a i n e d aggregates s u r r o u n d i n g garnet coronas. I n c l u s i o n s of t e t r a h e d r i t e ( C u 2 S b 4 S 1 3 ) , p y r a r g y r i t e (Ag 3SbS) and electrum (Au,Ag) have been observed w i t h i n the galena by Granges E x p l o r a t i o n ( S chroeter, 1981). Chalcopyrite (CuFeS 2), more p r e v a l e n t i n zone 2 than i n zone 1 ( F i g . 4.15), occurs as p e r v a s s i v e d i s s e m i n a t e d aggregates up t o 1 cm i n diameter i n v e i n l e t s a s s o c i a t e d w i t h p y r i t e , a r s e n o p y r i t e and galena ( P l a t e 4.14). C h a l c o p y r i t e i s a l s o found as e x s o l u t i o n s i n galena and s p h a l e r i t e , and as i n c l u s i o n s w i t h i n a r s e n o p y r i t e . Arsenopyrite (FeAsS) occurs i n both zone 1 and 2 ( F i g . 4.15). I t can comprise up t o 45% of s u l p h i d e v e i n l e t s but has not been observed as disseminated m i n e r a l i z a t i o n . I t almost always i s a s s o c i a t e d with p y r i t e . I n c l u s i o n s of s p h a l e r i t e , c h a l c o p y r i t e and galena are common. 232 PLATE 4.10: Photomicrograph o f brown s p e s s a r t i n e w i t h i n t e r s t i t i a l g a l e n a , zone 1, Capoose p r o s p e c t . BCMEMPR c o l l e c t i o n sample CAP-5-210. R e f l e c t e d l i g h t , p l a n e p o l a r i z e d l i g h t . PLATE 4.11: Photomicrograph o f p y r i t e and c h a l c o p y r i t e i n c l u s i o n s i n s p h a l e r i t e , zone 1, Capoose p r o s p e c t . BCMEMPR c o l l e c t i o n sample 79-CAP-4-504. R e f l e c t e d l i g h t , p l a n e p o l a r i z e d l i g h t . 233 PLATE 4.12: Photomicrograph o f c h a l c o p y r i t e e x s o l u t i o n s i n p y r i t e w i t h c o v e l l i t e , zone 1, Capoose p r o s p e c t . BCMEMPR c o l l e c t i o n sample CAP-5-434. R e f l e c t e d l i g h t , p l a n e p o l a r i z e d l i g h t . PLATE 4.13: Photomicrograph o f g a l e n a as ameboid b l e b s i n p y r i t e , zone 1, Capoose p r o s p e c t . BCMEMPR c o l l e c t i o n sample 79CAP-6-260. R e f l e c t e d l i g h t , p l a n e p o l a r i z e d l i g h t . 234 PLATE 4.14: Photomicrograph o f c h a l c o p y r i t e , p y r i t e , a r s e n o p y r i t e and g a l e n a assemblage, zone 2, Capoose p r o s p e c t . ( F i g . 4.15), BCMEMPR c o l l e c t i o n sample CAP80-39. R e f l e c t e d l i g h t , p l a n e p o l a r i z e d l i g h t . 235 T e t r a h e d r i t e , p y r a r g y r i t e and electrum have a l s o been seen as i n c l u s i o n s by Granges E x p l o r a t i o n L t d . P y r i t e (FeS 2) i s abundant i n both zones ( F i g . 4.15), o c c u r r i n g p r i m a r i l y as euhedral t o subhedral d i s s e m i n a t i o n s up t o 1 mm i n s i z e a s s o c i a t e d w i t h other s u l p h i d e s and garnet, or f r e q u e n t l y as the onl y s u l p h i d e . I t i s a l s o p r e s e n t as s c a t t e r e d cubes i n l a t e quartz and c a l c i t e v e i n l e t s . In p o l i s h e d s e c t i o n , p y r i t e i s l o c a l l y broken and f i l l e d i n t e r s t i t i a l l y w ith galena. P y r i t e a l s o occurs as e x s o l u t i o n b l e b s i n s p h a l e r i t e . L o c a l l y i t ho s t s <10u i n c l u s i o n s o f c h a l c o p y r i t e , p y r r h o t i t e , galena, s p h a l e r i t e and a r s e n o p y r i t e . 4.6.3 SILICATE PETROLOGY Garnet occurs throughout the r h y o l i t e as Mn-rich p i n k and brown anhedral c r y s t a l s up t o 2 mm i n diameter w i t h low, abnormal a n i s o t r o p y ; however, on l y the brown garnet aggregates are a s s o c i a t e d w i t h the major s u l p h i d e s i n zones 1 and 2. Pink garnet c r y s t a l s were not observed adjacent t o s u l p h i d e accumulations. Where brown garnet occurs w i t h s u l p h i d e s , the spaces between garnet c r y s t a l s are f i l l e d w i t h s u l p h i d e s ( P l a t e 4.10). Garnets o c c a s i o n a l l y appear "cracked" and broken; f r e q u e n t l y these c r a c k s are f i l l e d by s u l p h i d e s . Garnets can occur adjacent t o resorbed quartz phenocrysts, and are o f t e n surrounded by a p h a n i t i c coronas of muscovite and quartz. 236 Muscovite occurs with quartz as f i n e g r a i n e d aggregates surrounding s u l p h i d e and garnet accumulations. These coronas up t o 5 mm i n width envelop not o n l y s u l p h i d e and brown garnet accumulations, but a l s o i n d i v i d u a l p i n k garnets ( P l a t e s 4.15 and 4.IS). Quartz occurs as c o l o u r l e s s resorbed phenocrysts up t o 1 mm i n diameter a s s o c i a t e d with both p i n k and brown garnet. I t a l s o occurs w i t h muscovite as f i n e g r a i n e d coronas surrounding s u l p h i d e and garnet accumulations. Rare v e i n l e t s o f c o l o u r l e s s t o white quartz up t o 5 mm i n width occur i n l i t h i c wacke ( u n i t 5). These v e i n l e t s can sometimes c a r r y up t o 1 mm cubes of s i n g l e p y r i t e c r y s t a l s . Open space f i l l i n g t e x t u r e s such as v e i n l e t s w i t h cockade t e x t u r e s and drusy c a v i t i e s , are common. 4.6.4. METAL DISTRIBUTION Metal d i s t r i b u t i o n p a t t e r n s were examined mainly u s i n g data s u p p l i e d t o the w r i t e r by B.N. Church, T.G. Sch r o e t e r , and D.V. Lefebure. The data comprises 74 randomly d i s t r i b u t e d samples from the Capoose p r o p e r t y . Samples from B.N. Church were analysed by atomic a b s o r p t i o n spectrophotometry (AAS) a t Acme A n a l y t i c a l L a b o r a t o r i e s L t d . , Vancouver, B r i t i s h Columbia; those from T.G. S c h r o e t e r were analysed by AAS a t the B.C.M.E.M.P.R. l a b o r a t o r y i n V i c t o r i a , B r i t i s h Columbia. The assay data (Table 4.10) i n c l u d e Ag, Pb, Zn, Cu and Au value s r e p o r t e d i n ppm or ppb. 237 PLATE 4.15: Photomicrograph o f brown s p e s s a r t i n e w i t h coronas of s e r i c i t e and f i n e - g r a i n e d q u a r t z . R h y o l i t e , Sample KCP001, Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . PLATE 4.16: Photomicrograph o f p i n k s p e s s a r t i n e w i t h c o r o n a s of s e r i c i t e and f i n e - g r a i n e d q u a r t z . Q u a r t z g a r n e t r h y o l i t e , Sample KCP009, Capoose p r o s p e c t . T r a n s m i t t e d l i g h t , p l a n e p o l a r i z e d l i g h t . 238 TABLE 4.10: Trace element analyses o f rocks from the Capoose prospect, c e n t r a l B r i t i s h Columbia. Samples are l o c a t e d i n F i g u r e 4.18. SAMPLE SOURCE1 ELEMENT NUMBER Ag AU Pb Zn CU ppm ppm ppm ppm ppm CAP79-1-263 1 20 0.7 8100 ' 12000 280 CAP79-1-311 1 85 0.3 850 760 3800 CAP79-1-327 1 200 0-7 4300 100 210 CAP79-3-120 1 17, <0.3* 350 1900 1500 CAP79-3-142 1 <10~ 4 150 20 120 CAP79-3-227 1 <io 2 <0.3 2 1200 520 900 CAP79-4-211 1 <10 2 <0.3 2 150 5600 110 CAP79-5-194 1 183 0.8 10800 33800 710 CAP80-1 1 "195 2.06 1300 13300 1200 CAP80-3a 1 180 1.03 17500 57700 246 CAP80-5 1 6 100 260 69 CAP80-10 1 6 <lz 580 280 43 CAP80-11 1 4 320 1000 93 CAP80-29 1 3 <1 2 50 340 272 CAP80-31 1 690 4,11 54000 282000 168 CAP80-33 1 50 <l\ 2500 18000 520 CAP80-34 1 25 1300 16900 193 CAP80-35 1 65 2000 29900 1300 CAP80-36 1 2 <1 2 50 750 107 CAP80-37 1 270 2.06 30000 54700 382 CAP80-38 1 125 9.94 800 280 1800 CAP1 2 3.8 0.180 60 38 64 CAP 2 2 4.9 0.005 112 132 7 CAP 3 2 0.3 0.005 24 104 6 CAP4 2 0.1 0.005 16 72 1 CAP7 2 0.3 0.005 20 94 94 CAP9 2 1.2 0.005 56 132 13 CAP 13 2 15.0 0.070 1000 4700 225 CAP 14 2 1.9 0.005 42 240 165 CAP 15 2 0.8 0.005 35 104 43 CAP 16 2 '1.6 0.005 36 110 240 CAP 17 2 1.0 0.005 16 140 66 CAP 18 2 0.1 0.005 10 28 3 CAP20 2 0.2 0.005 20 78 70 CAP21 2 0.3 0.005 480 910 2 CAP22 2 0.2 0.005 25 41 13 CAP23 2 0.1 0. 005 16 64 6 CAP24 2 0.1 0.005 6 27 3 CAP25 2 0.1 0.005 15 88 23 CAP26 2 0.2 0.005 6 25 2 CAP27 2 0.1 0.005 5 43 4 CAP27b 2 0.1 0.005 20 50 4 CAP30 2 1.1 0.005 50 118 43 CAP31 2 1.2 0.005 30 415 76 CAP 3 2 2 0.3 0.005 44 460 16 239 TABLE 4.10: (continued) CAP 3 5 2 0.1 0.005 19 114 10 CAP36 2 0.1 0.005 25 80 9 CAP37 2 0.1 0.005 15 78 12 CAP 3 8 2 0.1 0.005 21 120 25 CAP 3 9 2 0.3 0.005 19 96 4 CAP41 2 0.1 0.005 14 52 11 CAP42 2 0.1 0.005 32 37 9 CAP43 2 0.1 0.005 18 6 1 CAP44 2 0.1 0.005 19 110 6 CAP46 2 0.1 0.005 14 166 3 CAP 4 7 2 0.01 0.005 11 80 13 CAP48 2 14.0 0.005 100 6 7 CAP49 2 0.8 0.005 22 890 13 CAP50 2 0.9 0.010 68 1000 2 CAPOS15W 2 0.4 0.015 21 130 12 CAP1S6W 2 0.2 0.005 32 125 6 CAP1S11W 2 5.8 0.005 275 950 32 CAPtrench2 2 190.0 0.350 8400 16300 1300 CAPtrench20 2 18.5 0.250 4100 330 102 CAPtrench21 2 617.0 6.15 88000 1600 430 CAPtrench23 2 42.5 0.500 9900 380 70 KCP012 3 1.5 96 16 KCP054 3 7.9 616 26 KAD042 3 15.6 102 29 1. Analyses were obtained from the f o l l o w i n g s o u r c e s : (1) Geochemical assay by ICP, T.G. Sch r o e t e r , B.C.M.E.M.P.R. l a b o r a t o r y , V i c t o r i a , B.C. (2) Geochemical assay by ICP, B.N. Church, Acme A n a l y t i c a l L a b o r a t o r i e s L t d . , Vancouver, B.C. (3) Geochemical assay by ICP, t h i s study, Cominco L t d . l a b o r a t o r y , Vancouver, B.C. Data p l o t t e d on l o g a r i t h m i c p r o b a b l i t y paper ( F i g . 4.17) were p a r t i t i o n e d i n t o p o p u l a t i o n s u s i n g the procedure o u t l i n e d by S i n c l a i r (1976). The means and standard d e v i a t i o n s f o r p a r t i t i o n e d p o p u l a t i o n s are i n T a b l e 4.11. Pb and Zn c o n s i s t of mixtures of 2 lognormal d i s t r i b u t i o n s . Cu and Ag r e p r e s e n t s i n g l e lognormal d i s t r i b u t i o n s . Au d i s t r i b u t i o n i s not e a s i l y l ognormally - r e p r e s e n t e d because many v a l u e s are e i t h e r below or a t the d e t e c t i o n l i m i t of 0.005 ppm. The p a r t i t i o n i n g of Pb and Zn i n t o 2 p o p u l a t i o n s c o n t r a s t s with Cu and Ag d i s t r i b u t i o n p a r t i t i o n i n g . The presence of t e t r a h e d r i t e , perhaps f r e i b e r g i t e , i n the s u l p h i d e assemblage, suggests t h a t Ag and Cu d e p o s i t i o n are r e l a t e d . P o s i t i v e c o r r e l a t i o n f o r Pb-Zn, Ag-Pb, and Ag-Zn was documented by Church and Diakow (1982). Pb and Zn p o p u l a t i o n s c o u l d t h e r e f o r e r e p r e s e n t a background l e a d and z i n c p o p u l a t i o n i n the Hazelton Group as w e l l as an anomalous l e a d and z i n c p o p u l a t i o n r e l a t e d t o s i l v e r and copper d e p o s i t i o n a s s o c i a t e d with the i n t r u s i o n of r h y o l i t e s i l l s . The r e l a t i o n s h i p of Au d e p o s i t i o n t o the o t h e r elements i s unknown. 4.6.5. DISCUSSION The Capoose p r o s p e c t i s t y p i f i e d by d i s s e m i n a t e d base and p r e c i o u s - m e t a l " g r e i s s e n - l i k e " m i n e r a l i z a t i o n hosted i n g a r n e t i f e r o u s r h y o l i t e . Dominant s u l p h i d e s i n c l u d e p y r i t e , s p h a l e r i t e , galena, c h a l c o p y r i t e and a r s e n o p y r i t e . 241 4.0 Cumulative Percent FIGURE 4.17: L o g a r i t h m i c p r o b a b i l i t y p l o t s i l l u s t r a t i n g d i s t r i b u t i o n o f A = Ag, B = Cu, C = Pb, and D = Zn from the Capoose p r o s p e c t . Means and standar d d e v i a t i o n s are i n Table 4.11. 242 6.0 Cumulative Percent FIGURE 4.17: L o g a r i t h m i c p r o b a b i l i t y p l o t s i l l u s t r a t i n g d i s t r i b u t i o n o f A = Ag, B = Cu, C = Pb, and D = Zn from the Capoose p r o s p e c t . Means and s t a n d a r d d e v i a t i o n s a re i n T a b l e 4.11. 243 TABLE 4.11: Means and standard d e v i a t i o n s determined g r a p h i c a l l y f o r p a r t i t i o n e d metal v a l u e s a t the Capoose prospect, c e n t r a l B r i t i s h Columbia. Data, p l o t t e d i n F i g u r e 4.19, a r e from Table 4.10. (Values below the d e t e c t i o n l i m i t were ev a l u a t e d a t an order of magnitude l e s s than the d e t e c t i o n l i m i t . ELEMENT UNITS POPULATION \ X b 2 b+s 3 b - s 4 Ag ppm A 100 0.40 25.1 0. 01 Pb ppm A 55 631 11220 40 ppm B 45 45 100 20 Zn % A 20 3.2 13 0. 79 ppm B 80 2.5 126 0.05 Cu ppm A 100 56 447 6.3 1. % of data i n p o p u l a t i o n 2. a n t i l o g of mean of lognormal p o p u l a t i o n 3. a n t i l o g of mean p l u s one standard d e v i a t i o n o f lognormal p o p u l a t i o n 4. a n t i l o g of mean p],us one standard d e v i a t i o n o f lognormal p o p u l a t i o n 244 T e t r a h e d r i t e and p y r r h o t i t e have been observed by Granges E x p l o r a t i o n i n minor amounts. Pr e c i o u s metals are i n t i m a t e l y a s s o c i a t e d with the s u l p h i d e s . Gold occurs as f r e e g r a i n s as w e l l as i n electrum; s i l v e r o ccurs as p y r a r g y r i t e and electrum. P r o b a b i l i t y graphs and c o r r e l a t i o n m a t r i c i e s i n d i c a t e t h a t a t l e a s t two m i n e r a l i z i n g events took p l a c e . The nature and d i s t r i b u t i o n of s u l p h i d e s and p r e c i o u s metals are used t o e s t i m a t e the p a r a g e n e t i c sequence i n r e l a t i o n t o m i n e r a l i z i n g events a t Capoose. P y r i t e , d i s t r i b u t e d throughout the d e p o s i t , occurs alone or a s s o c i a t e d with other s u l p h i d e s . T e x t u r a l evidence such as broken p y r i t e c r y s t a l s i n t e r s t i t i a l t o o t h e r s u l p h i d e s , the i n t i m a t e a s s o c i a t i o n of p y r i t e w i t h o t h e r s u l p h i d e s , and the occurrence of p y r i t e i n l a t e stage quartz and c a l c i t e v e i n l e t s suggest t h a t p y r i t e d e p o s i t e d throughout the m i n e r a l i z i n g h i s t o r y a t Capoose ( F i g . 4.18). The e a r l y p a r a g e n e t i c p o s i t i o n of galena i s supported by i t s f r a c t u r e d appearance. However, galena i s a l s o found as e x s o l u t i o n l i k e b l e b s i n c h a l c o p y r i t e , s p h a l e r i t e and p y r i t e . These r e l a t i o n s h i p s i n d i c a t e c o n t i n u e d galena d e p o s i t i o n . A r s e n o p y r i t e was the l a s t s u l p h i d e d e p o s i t e d as i n d i c a t e d by the presence of s p h a l e r i t e , c h a l c o p y r i t e and galena i n c l u s i o n s w i t h i n i t . The c l o s e a s s o c i a t i o n of a r s e n o p y r i t e with p y r i t e d u r i n g t h i s l a t e s t p a r a g e n e t i c p o s i t i o n confirms e a r l i e r evidence of c o n t i n u e d p y r i t e d e p o s i t i o n throughout the m i n e r a l i z i n g h i s t o r y a t Capoose. PYRITE GALENA CHALCOPYRITE SPHALERITE ARSENOPYRITE PYRARGYRITE — ELECTRUM — EARLY • LATE FIGURE 4.18: L i n e diagram i l l u s t r a t i n g e s t i m a t e d p a r a g e n e s i s of dominant s u l p h i d e s and p r e c i o u s metals a t Capoose. P y r a r g y r i t e and electrum, as i n c l u s i o n s w i t h i n the dominant s u l p h i d e s , d e p o s i t e d e a r l y i n the p a r a g e n e t i c sequence. These p r e c i o u s metals are thus u n r e l a t e d t o the l a t e s t stages of m i n e r a l i z a t i o n ( F i g . 4.18). I t appears t h a t a major m i n e r a l i z i n g event r e l a t e d t o i n t r u s i o n of g a r n e t i f e r o u s r h y o l i t e s i l l s a t Capoose f o l l o w e d by l a t e r d e p o s i t i o n of quartz and c a l c i t e v e i n l e t s . S p e c i f i c a l l y ( F i g . 4.18), the sequence was: (1) e a r l y d e p o s i t i o n of p y r i t e c l o s e l y f o l l o w e d by s p h a l e r i t e and galena w i t h a s s o c i a t e d t e t r a h e d r i t e , p y r a r g y r i t e and electrum, (2) l a t e r d e p o s i t i o n of minor galena, s p h a l e r i t e , c h a l c o p y r i t e , and p y r i t e , (3) continued d e p o s i t i o n o f p y r i t e and d e p o s i t i o n o f a r s e n o p y r i t e , and (4) d e p o s i t i o n o f quartz and c a l c i t e v e i n s c a r r y i n g minor p y r i t e p e r i p h e r a l t o m i n e r a l i z a t i o n . The r e l a t i o n s h i p o f m i n e r a l i z i o n and a l t e r a t i o n t o a g e n e t i c model f o r the d e p o s i t i s d i s c u s s e d i n s e c t i o n 4.9. T h i s s e c t i o n i n c o r p o r t a t e s the r e s u l t s o f s e c t i o n 4.8 t h a t d i s c u s s e s the hydrothermal environment of d e p o s i t i o n . 4.7 HYDROTHERMAL ENVIRONMENT OF DEPOSITION The Capoose prospect i s t y p i f i e d by di s s e m i n a t e d base and p r e c i o u s - m e t a l " g r e i s s e n - l i k e " m i n e r a l i z a t i o n hosted i n g a r n e t i f e r o u s r h y o l i t e s . Late stage quartz and c a l c i t e v e i n l e t s occur i n u n i t s p e r i p h e r a l t o the s i l l s ( s e c t i o n 4.6). F l u i d i n c l u s i o n and oxygen i s o t o p e s t u d i e s were done to examine some f e a t u r e s of the hydrothermal environment of 247 d e p o s i t i o n a t Capoose. S p e c i f i c a l l y , these s t u d i e s c o n s t r a i n : (1) the temperature, s a l i n i t y and depth of emplacement of p o s t - m i n e r a l i z i n g v e i n forming f l u i d s , (2) the temperature of emplacement of g a r n e t i f e r o u s r h y o l i t e s i l l s a s s o c i a t e d w i t h " g r e i s s e n - l i k e " m i n e r a l i z a t i o n , (3) the i s o t o p i c composition of m i n e r a l i z i n g and p o s t -m i n e r a l i z i n g f l u i d s , (4) the water t o rock r a t i o i n the hydrothermal system, and (5) the source of m i n e r a l i z i n g f l u i d s . D e f i n i n g the hydrothermal environment of d e p o s i t i o n at Capoose allows c l a s s i f i c a t i o n of the d e p o s i t , and comparison t o s i m i l a r B r i t i s h Columbia and w o r l d - c l a s s d e p o s i t s . 4.7.1. FLUID INCLUSION STUDY The f l u i d i n c l u s i o n study of two v e i n samples from the Capoose p r o p e r t y allows estimates o f : (1) the temperature of d e p o s i t i o n of p o s t - m i n e r a l i z i n g f l u i d s , (2) the s a l i n i t y of p o s t - m i n e r a l i z i n g f l u i d s , (3) the s i g n i f i c a n c e of b o i l i n g as a p r e c i p i t a t i o n mechanism f o r the v e i n s , and (4) the depth of v e i n emplacement. V e i n samples, taken from d r i l l core on zones 1 and 2, are l o c a t e d i n F i g u r e 4.19 and d e s c r i b e d i n Table 4.15. 4.7.1.1. Sample p r e p a r a t i o n and a n a l y s i s Two doubly p o l i s h e d t h i n s e c t i o n s were prepared c l o s e l y f o l l o w i n g the procedure o u t l i n e d by H o l l a n d e t a l . (1978), FIGURE 4.19: Sample l o c a t i o n s o f v e i n s used f o r f l u i d i n c l u s i o n a n a l y s e s from the Capoose p r o s p e c t . S e c t i o n B-B' i s l o c a t e d i n F i g u r e 4.1. Sample d e s c r i p t i o n s are i n Table 4.15. 249 S e c t i o n s were c u t 50 t o 100 urn t h i c k and p o l i s h e d w i t h t i n oxide. F l u i d i n c l u s i o n a n a l y s i s was c a r r i e d out u s i n g a Chiaxmeca h e a t i n g / f r e e z i n g stage. A t o t a l o f 13 f l u i d i n c l u s i o n s were analysed (Table 4.12). Measurements were c o r r e c t e d u s i n g c a l i b r a t i o n curves from McDonald (1987) . These curves demonstrate an accuracy of measurement t o w i t h i n 6.7°C wi t h a p r e c i s i o n o f 0.6°C (Id) f o r the temperature range -100°C t o +40°C, and t o w i t h i n 5.3°C w i t h a p r e c i s i o n of 2.2°C (Id) f o r the temperature range +40°C t o +420°C. 4.7.1.2. E r r o r a n a l y s i s Consecutive h e a t i n g and f r e e z i n g runs were made t o t e s t r e p r o d u c i b i l i t y o f homogenization and l a s t m e l t i n g temperatures. Heating r a t e s of about 5°C/minute were used t o w i t h i n 30°C o f homogenization a t which time r a t e s were decreased t o l-2°C/minute. Repeated measurements demonstrate a r e p r o d u c i b i l i t y t o w i t h i n 5°C and 2°C f o r homogenization and l a s t m e l t i n g temperatures r e s p e c t i v e l y . 4.7.1.3. F l u i d I n c l u s i o n Petrography F l u i d i n c l u s i o n s were observed from c a l c i t e and quartz v e i n s . The quartz v e i n l e t i s c h a r a c t e r i z e d by t i g h t , i n t e r l o c k i n g , c l e a r quartz c r y s t a l s (< 1 mm i n diameter) e n c l o s i n g randomly d i s p e r s e d fragments (up t o 2 mm i n length) o f host wacke ( u n i t 5). Some c h a l c e d o n i c i n f i l l i n g 250 TABLE 4.12: Homogenization and f r e e z i n g d ata f o r f l u i d i n c l u s i o n s from quartz v e i n s a t Capoose, c e n t r a l B r i t i s h Columbia. Data are p l o t t e d i n F i g u r e s 4.22 and 4.23. Sample l o c a t i o n s are i n F i g u r e 4.21. SAMPLE NO. INCLUSION ORIGIN1 (P/S,PS) HOMOG. TEMP <°C) LAST MELT . TEMP. <°C) EUTECTIC TEMP." < ° c > SALINITY eq. wt. % NaCl CALCITE: KDC 040 P 286 -27.6 -0.9 1.5 KDC 040 PS 297.8 KDC 040 P 299.1 KDC 040 P 291.2 KDC 040 P 286.1 QUARTZ: KDC 114 P 330.9 -26.1 -0.7 1.2 KDC 114 P 304.8 -26.8 -0.2 0.3 KDC 114 P 310.3 KDC 114 PS 321.4 KDC 114 PS 308 KDC 114 p 313.5 KDC 114 p 291 KDC 114 p 318.5 AVERAGE: p 302 -0.5 0.8 1. P = primary f l u i d i n c l u s i o n ; PS = pseudo-secondary f l u i d i n c l u s i o n ; S = secondary f l u i d i n c l u s i o n 251 i s seen i n the sample. The c a l c i t e v e i n l e t i s c h a r a c t e r i z e d by a mosaic of cracked rhombic c r y s t a l s s e a l e d by chalcedony. Primary (P), pseudosecondary (PS), or secondary (S) o r i g i n was c a r e f u l l y i d e n t i f i e d f o r each f l u i d i n c l u s i o n measured from Capoose (Table 4.12). Wherever p o s s i b l e , primary f l u i d i n c l u s i o n s t r a c i n g growth zones i n the quartz c r y s t a l s were measured. These i n c l u s i o n s are assumed t o r e p r e s e n t samples of f l u i d s trapped a t the same time of formation as the quartz host. Secondary f l u i d i n c l u s i o n s l y i n g along planes c r o s s c u t t i n g c r y s t a l boundaries were a l s o measured. These i n c l u s i o n s form i n healed m i c r o f r a c t u r e s and p r o v i d e i n f o r m a t i o n on f l u i d s p r e s e n t a f t e r growth of the quartz h o s t . Pseudosecondary f l u i d i n c l u s i o n s l y i n g along planes t e r m i n a t i n g a t c r y s t a l boundaries are assumed to r e p r e s e n t f l u i d s trapped i n f r a c t u r e s d u r i n g growth of the quartz host. Assignment of f l u i d i n c l u s i o n o r i g i n i s c r u c i a l t o i n t e r p r e t a t i o n of f l u i d i n c l u s i o n d ata w i t h i n a p a r a g e n e t i c framework (Roedder, 1976). Most f l u i d i n c l u s i o n s a t Capoose have two phases w i t h the dominant phase being l i q u i d . The most conspicuous s i n g l e f e a t u r e of a l l i n c l u s i o n s s t u d i e d i s a vapour bubble. The diameter of the vapour bubble i n each i n c l u s i o n was measured a t room temperature (Table 4.12) b e f o r e and a f t e r each h e a t i n g so t h a t any leakage induced by subsequent c o o l i n g c o u l d be measured ( c f . H o l l i s t e r e t a l . , 1981). No change i n vapour bubble diameter was observed i n the study. 252 V i s u a l e s t i m a t i o n s o f the amount of vapour phase present, made u s i n g a c h a r t g i v e n i n Roedder (1976) and r e p o r t e d i n Table 4.12, var y from 2 t o 10% with a mode of 5%. The s i z e of f l u i d i n c l u s i o n s ranged from 8.2 urn t o 32.8 um acro s s i n t h e i r l o n g e s t dimension. Most i n c l u s i o n s were l e s s than 30 um. 4.7.1.4 F r e e z i n g and h e a t i n g data F r e e z i n g and h e a t i n g s t u d i e s were conducted on the Chiaxmeca stage f o l l o w i n g o p e r a t i n g procedures o u t l i n e d by Bloom (1979). Because f r e e z i n g i s l e s s l i k e l y t o d i s t o r t i n c l u s i o n s i n qu a r t z , a l l o b s e r v a t i o n s were completed i n the f r e e z i n g mode b e f o r e proceeding t o the h e a t i n g phase. A l l i n c l u s i o n s used f o r f r e e z i n g s t u d i e s were super-c o o l e d t o approximately -100°C. Slow h e a t i n g (averaging 2°C/minute) from -100°C t o about +5°C enabled d e t e r m i n a t i o n of the temperature o f i n i t i a l m e l t i n g ( e u t e c t i c temperature, Table 4.13) and the temperature o f l a s t m e l t i n g . Due t o the o p a c i t y of p a r t s o f the p l a t e s and the s m a l l s i z e o f many i n c l u s i o n s , f r e e z i n g temperatures and phase changes c o u l d o n l y be observed i n t h r e e f l u i d i n c l u s i o n s . E u t e c t i c tempertures, which r e p r e s e n t the f i r s t i c e m e l t i n g , range from -26.1°C t o -27.6°C (Table 4.13). No meaningful d i s t i n c t i o n can be made between e u t e c t i c temperatures from f l u i d i n c l u s i o n s hosted i n quartz and c a l c i t e ( F i g . 4.20). L a s t m e l t i n g temperatures range from -0.9°C t o -0.2°C. 253 TABLE 4.13: Summary of e u t e c t i c and l a s t m e l t i n g temperatures from f l u i d i n c l u s i o n s , Capoose pros p e c t , c e n t r a l B r i t i s h Columbia. Data are p l o t t e d i n F i g u r e 4.22. SAMPLE VEIN NUMBER OF EUTECTIC LAST MELTING NUMBER TYPE MEASUREMENTS TEMPERATURE TEMPERATURE °C °C KDC040 CALCITE 1 -27.6 -0.9 KDC114 QUARTZ 2 -26.5 + 0.4 -0.8 + 0.5 VEIN TYPE EUTECTIC TEMPERATURE (°C) LAST MELTING TEMPERATURE FIGURE 4.20: E u t e c t i c and l a s t m e l t i n g temperatures o f i n c l u s i o n s from quartz and c a l c i t e v e i n s from the Capoose p r o s p e c t . F r e e z i n g data a r e i n T a b l e 4.12. CO Ul 255 Homogenization temperatures were determined f o r 13 i n c l u s i o n s from d i f f e r e n t v e i n types (Table 4.14). Heating r a t e s of about 10°C/minute were used to w i t h i n 3 0°C of homogenization a t which time r a t e s were decreased t o 2°C/minute. Homogenization data are p l o t t e d , u s i n g a c l a s s i n t e r v a l of 5°C, f o r each o r i g i n and v e i n type ( F i g . 4.21). Primary, pseudosecondary and secondary f l u i d i n c l u s i o n s from both v e i n types are unimodally d i s t r i b u t e d from 285°C t o 335°C, with a mode of 3 02°C. Most quartz i n c l u s i o n homogenization temperatures are g r e a t e r than 300°C. Homogenization temperatures from i n c l u s i o n s i n c a l c i t e are l e s s than 3 00°C. 4.7.1.5 I n t e r p r e t a t i o n F l u i d i n c l u s i o n s from p o s t - m i n e r a l i z i n g v e i n s a t Capoose have low c o n c e n t r a t i o n s of d i s s o l v e d s a l t s as determined from l a s t m e l t i n g temperatures r a n g i n g from -0.9°C t o -0.2°C (Table 4.13). E u t e c t i c m e l t i n g i n these i n c l u s i o n s (-26.1° t o -27.6°C) c l o s e l y approximates the metastable e u t e c t i c melt i n the H 20-NaCl system (about -28°C) which suggests t h a t s a l i n i t y can be l a r g e l y a t t r i b u t e d t o NaCl (Roedder, 1984). L a s t m e l t i n g temperatures correspond t o d i s s o l v e d s a l t contents of between 0.3 and 1.5 weight p e r c e n t NaCl e q u i v a l e n t . Thus s a l i n i t i e s o f f l u i d i n c l u s i o n s from v e i n s a t Capoose r e p r e s e n t samples of hydrothermally d r i v e n low s a l t content waters which passed through these rocks a f t e r the m i n e r a l i z i n g event. 256 TABLE 4.14: Summary of homogenization temperatures from f l u i d i n c l u s i o n s from d i f f e r e n t v e i n types, Capoose prospect, c e n t r a l B r i t i s h Columbia. Data are p l o t t e d i n F i g u r e 4.23. VEIN INCLUSION NUMBER OF AVERAGE TEMPERATURE TYPE TYPE MEASUREMENTS OF HOMOGENIZATION QUARTZ P 6 312 + 12 °C PS 2 315 + 7 °C CALCITE P 4 291 ± 5 °C PS 1 298°C 1 H O M O G E N I Z A T I O N T E M P E R A T U R E C O FLUID INCLUSION ORIGIN TYPE CO U l CJ z u or or U o o u. o d z 3 -2 . P S B J O O S E C O N D A R Y P R I M A R Y H O M O G E N I Z A T I O N T E M P E R A T U R E (°C) FIGURE 4.21: A) Homogenization temperature v s . v e i n type, and B) homogenization temperature v s . o r i g i n type f o r f l u i d i n c l u s i o n s from quartz and c a l c i t e v e i n s from w the Capoose p r o s p e c t . Data a r e i n Tab l e 4.12. ^ 258 Homogenization temperatures ( a l l t o the l i q u i d phase), from 285°C t o 335°C, represent the minimum temperature of t r a p p i n g o f the f l u i d s a t time of formation of the host. On the b a s i s of open space f i l l i n g t e x t u r e s seen i n quartz and c a l c i t e v e i n s , the p o s t - m i n e r a l i z i n g hydrothermal system a t Capoose formed a t shallow depths. Pressure c o r r e c t i o n t o measured temperatures, t h e r e f o r e probably i s n e g l i g i b l e and temperatures of homogenization approximately equal the temperature of t r a p p i n g . Evidence f o r b o i l i n g i n p r e - m i n e r a l i z i n g v e i n s a t Capoose i s not documented. However, the data s e t a v a i l a b l e i s s m a l l and t h e r e f o r e p o t e n t i a l f o r o b s e r v a t i o n i s l i m i t e d . Assuming the p o s t - m i n e r a l i z i n g f l u i d s a t Capoose were b o i l i n g , c a l c u l a t i o n of minimum depths of emplacement of quartz and c a l c i t e v e i n s i s p o s s i b l e (Haas, 1971). Us i n g equations developed by Haas (1971), the v e i n s have a d e n s i t y of 0.725 g/cm3 and a vapour pr e s s u r e of 91.2 b a r s . C a l c u l a t e d vapour p r e s s u r e s r e p r e s e n t c o n f i n i n g p r e s s u r e s on f l u i d s t h a t are b o i l i n g d u r i n g d e p o s i t i o n . In most n a t u r a l s i t u a t i o n s , c o n f i n i n g p r e s s u r e s are between h y d r o s t a t i c and l i t h o s t a t i c l i m i t s (Roedder, 1984). Under h y d r o s t a t i c c o n d i t i o n s , maximum depths of emplacement are 1140 m. Under l i t h o s t a t i c c o n d i t i o n s , u s i n g a mean rock d e n s i t y o f 2.7 g/cm3, the maximum depths of emplacement i s 340 m. The r e f o r e , d e p o s i t i o n of early-formed quartz and c a l c i t e v e i n s took p l a c e a t minimum depths between 340 m and 1140 m. 259 4.7.2 STABLE ISOTOPE STUDY A s t a b l e i s o t o p e study of 10 samples was done under the s u p e r v i s i o n of T.K. Kyser a t the U n i v e r s i t y of Saskatchewan, Saskatoon. The o b j e c t i v e s of the study were t o : (1) c a l c u l a t e the temperature of emplacement of g a r n e t i f e r o u s r h y o l i t e s i l l s a s s o c i a t e d with " g r e i s e n - l i k e 1 1 m i n e r a l i z a t i o n , (2) determine the oxygen i s o t o p i c composition of m i n e r a l i z i n g and p o s t - m i n e r a l i z i n g v e i n forming f l u i d s , (3) d i r e c t l y measure the hydrogen i s o t o p e composition of waters e x t r a c t e d from s e r i c i t e a s s o c i a t e d with m i n e r a l i z a t i o n ( s e c t i o n 4.6.1), (4) e s t i m a t e the water t o rock r a t i o a t the time of m i n e r a l i z a t i o n and p o s t -m i n e r a l i z a t i o n , and (5) suggest the source o f m i n e r a l i z i n g f l u i d s . The d i r e c t approach f o r measuring oxygen i s o t o p e compositions was not taken because water p r e s e n t i n f l u i d i n c l u s i o n s of oxygen-bearing m i n e r a l s undergoes exchange wit h the host m i n e r a l d u r i n g c o o l i n g , thus changing the 1 8 0 y l 6 0 r a t i 0 o f t h e f i u i d (Rye and O ' N e i l , 1968). Th e r e f o r e , oxygen i s o t o p e compositions of the m i n e r a l i z i n g f l u i d a t Capoose were measured i n d i r e c t l y by i s o t o p i c a n a l y s i s of m i n e r a l assemblages, c a l c u l a t i o n of temperatures of formation u s i n g f l u i d i n c l u s i o n s and p u b l i s h e d experimental data (Carmichael e t a l . , 1974), and a p p l i c a t i o n of e x p e r i m e n t a l l y d e r i v e d f r a c t i o n a t i o n f a c t o r s . 4.7.2.1 Sample p r e p a r a t i o n and a n a l y s i s 260 Eighteen analyses of ten samples from Capoose were used, i n c l u d i n g t h r e e v e i n samples, seven whole rock samples and e i g h t m i n e r a l separates (Table 4.15; F i g . 4.22). M i n e r a l s e p a r a t i o n f o r quartz was achieved by coarse c r u s h i n g i n an agate mortar f o l l o w e d by h e a t i n g the sample i n c o n c e n t r a t e d HCl. M i n e r a l s e p a r a t i o n f o r c a l c i t e was achieved by coarse c r u s h i n g i n an agate mortar f o l l o w e d by immersing the sample i n h y d r o f l u o r i c a c i d . Whole rock samples were p u l v e r i z e d to l e s s than 200 mesh s i z e f r a c t i o n i n a tungsten c a r b i d e r i n g m i l l . M i n e r a l s e p a r a t e s were hand-picked from a -30 t o +60 s i z e f r a c t i o n under a b i n o c u l a r microscope, and washed u l t r a s o n i c a l l y i n d i s t i l l e d water. V e i n samples and mineral separates were ana l y s e d by XRD t o c o n f i r m p u r i t y of sample powders p r i o r t o i s o t o p i c a n a l y s i s . Compositions of whole rock samples were determined by XRF. D i r e c t a n a l y s i s of hydrogen i s o t o p e compositions by e x t r a c t i o n of waters from s e r i c i t e r e q u i r e d 1 g of pure s e r i c i t e . I n d i r e c t analyses of oxygen i s o t o p e compositions by a n a l y s i s of m i n e r a l or rock powders r e q u i r e d 5 t o 18 mg of sample. V a r i a t i o n s i n the i s o t o p i c r a t i o s of hydrogen and oxygen were measured by mass-spectrometer on H 2 and C0 2 gases, r e s p e c t i v e l y , t h a t were e x t r a c t e d q u a n t i t a t i v e l y from the m i n e r a l s . Hydrogen i s o t o p e compositions were measured u s i n g the U-technique d e s c r i b e d by B i g e l e i s e n e t a l . (1952) as m o d i f i e d by Kyser and O'Niel (1984). Oxygen f o r oxygen 261 TABLE 4.15: Oxygen i s o t o p e compositions o f v e i n , whole rock, and phenocryst separate samples from the Capoose prospect, c e n t r a l B r i t i s h Columbia. Sample l o c a t i o n s are i n F i g u r e 4.24. Data are p l o t t e d i n F i g u r e 4.25. SAMPLE SAMPLE DESCRIPTION <l±o0 NUMBER VEIN SAMPLES KDC 040 CALCITE VEIN - (DDH031-229m) 3.4 C a l c i t e v e i n l e t 2 cm wide; p y r i t e forms d i s c o n t i n u o u s v e i n s e l v a g e s i n a d j a c e n t r h y o l i t e . KDC 114 QUARTZ VEIN - (DDH057-55m) 8.8 Narrow quartz v e i n l e t (5 mm wide) i s w i t h i n l i t h i c wacke. WHOLE ROCK SAMPLES GCP013 WHOLE ROCK - DACITE 1% anhedral embayed quartz phenocrysts (< 1 mm i n diameter) and 1% subhedral p l a g i o c l a s e phenocrysts (< 1 mm i n diameter) are suspended i n a c r y p t o c r y s t a l l i n e groundmass. 5% a l t e r a t i o n o f ma f i c m i n e r a l s t o c h l o r i t e i s e v i d e n t . The sample "contains 3% i l m e n i t e . 9.4 GCP018 WHOLE ROCK - BASALTIC ANDESITE 7.9 The sample has undergone r e g i o n a l g r e e n s c h i s t a l t e r a t i o n changing hornblende and pyroxene c r y s t a l s mostly t o c h l o r i t e (20%). F e l t -t e x t u r e d groundmass i s composed o f p l a g i o c l a s e and q u a r t z . KCP009 WHOLE ROCK - QUARTZ GARNET RHYOLITE 7.5 Sample i s c h a r a c t e r i z e d by 7% embayed quartz phenocrysts (1 t o 2 mm a c r o s s ) , and 3% anhedral garnet c r y s t a l s i n a d e v i t r i f i e d a p h a n i t i c f e l t - t e x t u r e d groundmass. Garnets are zoned and rimmed by muscovite and q u a r t z . KCP012 WHOLE ROCK - GARNET RHYOLITE 8.0 5% anhedral garnet c r y s t a l s (1 mm i n diameter) are interwoven with quartz aggregates (2 mm i n diameter) and surrounded by a f e l t - t e x t u r e d a p h a n i t i c groundmass. Lithophysae, seen i n t h i n s e c t i o n , are l i n e d with q u a r t z . TABLE 4.15: (continued) KCP028 WHOLE ROCK - QUARTZ GARNET PORPHYRY 5.4 T h i s sample i s c h a r a c t e r i z e d by 3% broken and embayed quartz c r y s t a l s and 1% anhedral garnet i n a f e l t - t e x t u r e d groundmass showing ghost f e l d s p a r s . KCP035 WHOLE ROCK - FELSITE -1.6 T h i s i s an a p h a n i t i c f e l s i c v o l c a n i c rock w i t h m i c r o s p h e r u l i t e s . KCP054 WHOLE ROCK - GARNET RHYOLITE 7.3 T h i s sample i s c h a r a c t e r i s e d p r i m a r i l y by 5% anhedral garnets (< 1 mm i n d i a m e t e r ) . Garnets are i n t e r s p e r s e d through, and con c e n t r a t e d between, s p h e r u l i t e - l i k e b a l l s which range from 1 mm t o 2 cm i n diameter. KAD042 WHOLE ROCK - RHYOLITE (ALTERED) The sample i s h i g h l y s e r i c i t i z e d (60%) with up t o 1% disseminated c u b i c p y r i t e . -2. 0 MINERAL SEPARATES FROM UNITS DESCRIBED ABOVE KCP009 QUARTZ PHENOCRYST SEPARATE 8. 1 KCP009 GARNET (FE-RICH) PHENOCRYST SEPARATE 4 . 6 KCP009 GARNET (FE-POOR) PHENOCRYST SEPARATE 5. 2 KCP012 QUARTZ PHENOCRYST SEPARATE 8. 0 KCP012 GARNET (FE-RICH) PHENOCRYST SEPARATE 4. 8 KCP054 QUARTZ PHENOCRYST SEPARATE 8. 4 KCP054 GARNET (FE-RICH) PHENOCRYST SEPARATE 3 . 9 KAD042 SERICITE -4. 0 1. A l l s t a b l e i s o t o p e analyses were done i n the l a b o r a t o r y of T.K. Kyser, Department of 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 Saskatchewan. 263 FIGURE 4.22: Sample l o c a t i o n s o f whole rock, v e i n and m i n e r a l separate samples used f o r s t a b l e i s o t o p e analyses from the Capoose prospect. See F i g u r e 4.20 f o r sample l o c a t i o n s from d r i l l c o r e. i s o t o p e measurements was e x t r a c t e d by the B r F 5 technique (Clayton and Mayeda, 1963). A l l s t a b l e i s o t o p e a n a l y s e s used c o n v e n t i o n a l i s o t o p e r a t i o mass spectrometry and are re p o r t e d u s i n g the d n o t a t i o n i n u n i t s of per m i l ( ° / 0 0 ) r e l a t i v e t o SMOW standard (Standard Mean Ocean Water). 4.7.2.2 E r r o r analyses R e p l i c a t e analyses o f v e i n , whole rock and m i n e r a l separate samples are r e p r o d u c i b l e w i t h a p r e c i s i o n o f + 0.2 per m i l (2d) f o r d 1 8 0 (Table 4.16) and + 5 per m i l (2d) f o r dD (Kyser, p e r s . comm., 1987). The d 1 8 0 v a l u e o f the NBS-28 quartz standard i s 9.6 (Kyser, p e r s . comm., 1987). Standard samples are r e p r o d u c i b l e with, a n accuracy o f + 0.1 per m i l (Table 4.16). 4.7.2.3 Geothermometry M i n e r a l separates i n the form of quartz and gar n e t phenocryst p a i r s were analysed t o estimate the temperature of formation o f g a r n e t i f e r o u s r h y o l i t e s i l l s ( u n i t s 6, 7 and 8) a s s o c i a t e d w i t h m i n e r a l i z a t i o n a t Capoose. Quartz and garnet m i n e r a l separates from the s i l l s are assumed t o have formed i n i s o t o p i c e q u i l i b r i u m . F r a c t i o n a t i o n f a c t o r s f o r these m i n e r a l p a i r s have been determined e x p e r i m e n t a l l y a l l o w i n g c a l c u l a t i o n of the temperature o f d e p o s i t i o n : Equation 4 . 1 . QUARTZ-GARNET (Bot t i n g a and Javoy, 1975): T(K) = 1.7 ( 1 0 3 ) / ( A q u a r t z - g a r n e t ) V 2 where A x y = A Q G = d 1 8 0 - d 1 8 0 g a r n e t TABLE 4.16: C o n t r o l samples analysed w i t h the oxygen i s o t o p e s u i t e from the Capoose p r o s p e c t , c e n t r a l B r i t i s h Columbia. SAMPLE NO. DUPLICATE 1 DUPLICATE 2 STANDARD <°/oo> <°/oo> <°/0o> KCP009 4.6 5.2 GARNET MINERAL SEPARATE AGS 1 9.5 QUARTZ SAND 1. The v a l u e o f the AGS standard i s d 1 8 0 = 9.6 °/ 266 T = temperature (K) temperature range > 500°C. At Capoose, quartz phenocrysts from the s i l l s have v a l u e s from 8.0 t o 8.4 ° / 0 0 , and garnet phenocrysts have v a l u e s between 3.9 and 5.2 ° / O Q (Table 4.15). Values f o r these phenocrysts are w i t h i n t h i s range of n a t u r a l l y o c c u r i n g u n a l t e r e d m i n e r a l s — d 1 8 0 f o r quartz i s between 6 and 13 ° / 0 0 and d 1 8 0 f o r garnet i s between 3 and 10 ° / 0 0 ( F i e l d and F i f a r e k , 1985). Equation 4.1 t h e r e f o r e g i v e s p r o b a b l y magmatic temperatures of formation f o r the s i l l s of 528°C t o 725°C (Table 4.9). 4.7.2.4 I s o t o p i c composition of m i n e r a l i z i n g f l u i d s Oxygen i s o t o p e compositions o f d e p o s i t i o n a l f l u i d s were c a l c u l a t e d i n d i r e c t l y by i s o t o p i c a n a l y s i s o f m i n e r a l assemblages. Assumptions, techniques and r e s u l t s a re below. At e q u i l i b r i u m , i s o t o p i c s p e c i e s p a r t i t i o n ( f r a c t i o n a t e ) among a v a i l a b l e s i t e s i n c o e x i s t i n g m i n e r a l s and f l u i d through mass-dependent d i f f e r e n c e s i n chemical and p h y s i c a l behaviour. The p a r t i t i o n i n g of two i s o t o p e s between two s p e c i e s , X and Y, i s d e s c r i b e d by the f r a c t i o n a t i o n f a c t o r , a xy = R x / R y ( w ^ e r e R i s the i s o t o p e r a t i o , f o r example D/H or 1 8 0 / 1 6 0 ) . The degree o f f r a c t i o n a t i o n , independent of pressure because of the n e a r l y i d e n t i c a l volume of heavy and l i g h t i s o t o p e s (Sheppard, 1977), v a r i e s i n v e r s e l y with temperature i n a p r e d i c t a b l e way (Urey, 1947; B i g e l e i s e n and Mayer, 1947). Thus, the 267 i s o t o p i c composition can be i n d i r e c t l y c a l c u l a t e d g i v e n : ( l ) a n a l y t i c a l i s o t o p e data from a mineral t h a t was i n e q u i l i b r i u m with the hydrothermal f l u i d , (2) the f r a c t i o n a t i o n c o e f f i c i e n t ( ) between t h a t m i n e r a l and water, and (3) an independent estimate of temperature of formation of the m i n e r a l through f l u i d i n c l u s i o n s or o t h e r geothermometers. Whole rock samples from g a r n e t i f e r o u s r h y o l i t e s i l l s a t Capoose have v a l u e s from 5.4 to 8.0 ° / 0 0 . These compositions are w i t h i n the l i m i t s f o r normal r h y o l i t e s ( d 1 8 0 = 6 t o 13 °/ 0 0) and do not r e f l e c t d e p l e t i o n of w a l l r o c k by l a r g e volumes of Late Cretaceous or e a r l y T e r t i a r y low 1 8 0 content hydrothermal f l u i d s . S i n c e m i n e r a l i z a t i o n i s a s s o c i a t e d with i n t r u s i o n of the s i l l s ( s e c t i o n 4.6.4), the oxygen i s o t o p e compositions of f l u i d s i n e q u i l i b r i u m w i t h these s i l l s i s c a l c u l a t e d u s i n g : (1) the whole rock a n a l y t i c a l i s o t o p e data from the s i l l s (Table 4.15), (2) the p l a g i o c l a s e ( A n 3 0 ) - w a t e r f r a c t i o n a t i o n curves of O'Neil and T a y l o r (1969; equation 4.3), which assume t h a t the measured d 1 8 0 whole rock value i s equal t o the d 1 8 0 v a l u e of p l a g i o c l a s e ( A n 3 0 ) (Ta y l o r , 1979), and (3) the average c a l c u l a t e d temperature of formation of the s i l l s of 642°C from q u a r t z - g a r n e t phenocrysts (Table 4.17). R e s u l t s of these c a l c u l a t i o n s show a narrow spread o f i s o t o p i c composition i n the d e p o s i t i o n a l f l u i d s of between d x o O = 5.7 and 8.3 ° / 0 0 -4.7.2.5 I s o t o p i c composition of p o s t - m i n e r a l i z i n g f l u i d s Oxygen i s o t o p e compositions f o r p o s t - m i n e r a l i z i n g f l u i d s were c a l c u l a t e d i n d i r e c t l y by i s o t o p i c a n a l y s i s o f mine r a l assemblages. Techniques and r e s u l t s f o l l o w . The hydrogen i s o t o p i c compositions o f f l u i d s i n e q u i l i b r i u m w i t h p h y l l i c a l t e r a t i o n was d i r e c t l y measured by e x t r a c t i n g waters from a pure s e r i c i t e sample. The v a l u e was -155 ° / 0 0 . The oxygen i s o t o p e compositions o f d e p o s i t i o n a l f l u i d s i n e q u i l i b r i u m w i t h p h y l l i c a l t e r a t i o n a t Capoose were a l s o c a l c u l a t e d . S i n c e p h y l l i c a l t e r a t i o n i s a s s o c i a t e d with c o l l a p s e of m e t e o r i c a l l y d r i v e n f l u i d s onto c o o l e d magmatic rocks, the temperature o f f l u i d s i n e q u i l i b r i u m with the quartz and c a l c i t e v e i n s i s used f o r the temperature o f f l u i d s i n e q u i l i b r i u m w i t h s e r i c i t e . C a l c u l a t i o n s were made u s i n g : (1) the a n a l y t i c a l oxygen i s o t o p e data from s e r i c i t e i n e q u i l i b r i u m w i t h the f l u i d s (Table 4.15), (2) the muscovite-water f r a c t i o n a t i o n curves of e q uation 4.2, and (3) the temperature o f d e p o s i t i o n o f f l u i d s i n e q u i l i b r i u m w i t h the quartz and c a l c i t e v e i n s ( s e c t i o n 4.7.2.4). Equation 4.2. MUSCOVITE-WATER (O'Neil and T a y l o r , 1969): 1 0 0 0 1 n «(muscovite-water) =2.38(10 6)/T 2 - 3.89 where T = temperature (K), and temperature range = 4 00°C t o 65 0 ° C — c a n be e x t r a p o l a t e d t o 300°C. R e s u l t s o f these c a l c u l a t i o n s (Table 4.17) show oxygen i s o t o p i c compositions i n the d e p o s i t i o n a l f l u i d s o f -8.6 t o 269 TABLE 4.17: A d i r e c t l y measured hydrogen i s o t o p e c o m p o s i t i o n 1 and i n d i r e c t l y c a l c u l a t e d oxygen i s o t o p e compositions ( s e c t i o n 4.7.2) o f hydrothermal f l u i d s a t the Capoose p r o p e r t y , c e n t r a l B r i t i s h Columbia. SAMPLE NUMBER d 1 8 0 VEIN d 1 80 WHOLE ROCK TEMPERATURE °C d 1 8 0 WATER KDC040 3. 4 * 292 -2.4 KDC114 8. 8 312 1.8 GCP013 9.4 302 4.9 GCP018 7.9 302 3.4 KCP009 7.5 642 7.8 KCP012 8.0 642 8.3 KCP028 5.4 642 5.7 KCP054 7.3 642 7.6 KAD042 -2.0 302 -6.6 KAD042 -4.0 302 -8.6 dD -158 1. A l l s t a b l e i s o t o p e analyses were done i n the l a b o r a t o r y of T.K. Kyser, Department of 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 of Saskatchewan. 270 The oxygen i s o t o p e compositions of p o s t - m i n e r a l i z a t i o n v e i n forming f l u i d s were c a l c u l a t e d assuming e q u i l i b r i u m with late-formed quartz and c a l c i t e v e i n s . S i n c e these v e i n s p r e c i p i t a t e d i n open spaces ( s e c t i o n 4.6.1) i n an d e s i t e , d a c i t e and l i t h i c wacke of the H a z e l t o n Group ( s e c t i o n 4.2.2), f l u i d i n c l u s i o n temperatures ( s e c t i o n 4.7.1) from the v e i n s are used t o c a l c u l a t e d oxygen i s o t o p e compositions o f f l u i d i n e q u i l i b r i u m w i t h these m i n e r a l s . The oxygen i s o t o p e compositions of hydrothermal f l u i d s i n e q u i l i b r i u m w i t h early-formed quartz v e i n s a t Capoose were c a l c u l a t e d u s i n g : (1) the a n a l y t i c a l i s o t o p e data from the v e i n s (Table 4.15), (2) the experimental quartz-water f r a c t i o n a t i o n curves o f equation 4.3, and (3) averaged primary f l u i d i n c l u s i o n data f o r quartz ( s e c t i o n 4.7.1). Equation 4 .3 . QUARTZ-WATER (Clayton e t a l . , 1972): 1 0 0 0 1 n « ( q u a r t z _ w a t e r ) = 3.38(10 6/T 2)-2.90 where T = temperature (K) and temperature range = 200 t o 500°C. R e s u l t s of these c a l c u l a t i o n s (Table 4.17) show the i s o t o p i c compositon o f the d e p o s i t i o n a l f l u i d s t o be d 1 8 0 = 1.8 ° / 0 0 -The oxygen i s o t o p e compositions of hydrothermal f l u i d s i n e q u i l i b r i u m w i t h late-formed c a l c i t e v e i n s a t Capoose were c a l c u l a t e d u s i n g : (1) the a n a l y t i c a l i s o t o p e data from the v e i n s (Table 4.15), (2) the experimental c a l c i t e - w a t e r f r a c t i o n a t i o n curves o f Friedman and O'Neil (1977), and (3) averaged primary f l u i d i n c l u s i o n data f o r c a l c i t e ( s e c t i o n 4.7.1). 271 Equation 4.4. CALCITE-WATER (Friedman and O ' N e i l , 1977): 1 0 0 0 1 n « ( c a l c _ w a t e r ) = 2.78(10 6/T 2) - 2.89 where T = temperature (K), and temperature range = 0°C t o 500°C. R e s u l t s o f these c a l c u l a t i o n s (Table 4.17) show an i s o t o p i c compositon i n the d e p o s i t i o n a l f l u i d s d 1 8 0 = -2.4 ° / 0 0 . The oxygen i s o t o p e composition o f l a t e d e p o s i t i o n a l f l u i d s i n e q u i l i b r i u m with a n d e s i t e and d a c i t e o f the Hazelton Group was c a l c u l a t e d u s i n g the assumptions of T a y l o r (1979) where the measured d 0 whole rock v a l u e i s 1 o equal t o the d 0 va l u e of p l a g i o c l a s e ( A n 3 0 ) . C a l c u l a t i o n s were made u s i n g : (1) the whole rock a n a l y t i c a l i s o t o p e data (Table 4.15), (2) the p l a g i o c l a s e ( A n 3 0 ) - w a t e r curves o f equation 4.5, and (3) an estimated minimum temperature o f formation of the rock of 302°C (from f l u i d i n c l u s i o n s , s e c t i o n 4.7.1). Equation 4.5. PLAGIOCLASE(An 3 Q)-WATER (O'Neil and T a y l o r , 1967): 1 0 0 0 1 n * ( p l a g > _ w a t e r ) = 2.68(10 6/T 2)-3.53 where T = temperature (K) and the temperature range = any g e o l o g i c a l l y reasonable temperature R e s u l t s of these c a l c u l a t i o n s (Table 4.17) g i v e i s o t o p i c compositions o f l a t e f l u i d s between d 0 = 1.3 and 4.8 / 0 0 . In summary, oxygen i s o t o p e compositions o f f l u i d s i n e q u i l i b r i u m with r h y o l i t e s i l l s a t Capoose have oxygen i s o t o p e compositions from 5.7 t o 8.3 ° / O Q - These f l u i d s are a s s o c i a t e d w i t h m i n e r a l i z a t i o n on the p r o p e r t y ( s e c t i o n 4.6.1). F l u i d s i n e q u i l i b r i u m with p h y l l i c a l t e r a t i o n , quartz and c a l c i t e v e i n s and Hazelton Group rocks have oxygen i s o t o p e compositions from -8.6 t o 4.9 ° / 0 0 . Post-m i n e r a l i z i n g f l u i d s have lower d 1 8 0 v a l u e s than those c a l c u l a t e d from the s i l l s . 4.7.2.6 Water t o rock r a t i o of p o s t - m i n e r a l i z i n g f l u i d s The water t o rock r a t i o of the p o s t - m i n e r a l i z i n g f o s s i l hydrothermal system a t Capoose can be c a l c u l a t e d assuming i s o t o p i c e q u i l i b r i u m between w a l l r o c k and f l u i d s (Ohmoto and Rye, 1974). U n a l t e r e d a n d e s i t i c rocks t y p i c a l l y have a d 1 8 0 v a l u e of about 7 ° / 0 0 ( F i e l d and F i f a r e k , 1985) . A n d e s i t i c and d a c i t i c H a z e l t o n Group rocks from Capoose have not been exposed t o l a t e hydrothermal f l u i d s and have d 1 8 0 v a l u e s very s i m i l a r t o t h i s norm (Table 4.18). The water t o rock r a t i o i s dependent on temperature, the d 1 8 0 v a l u e of the hydrothermal f l u i d , and the d i f f e r e n c e between a l t e r e d and u n a l t e r e d v a l u e s . •I Q C a l c u l a t i o n of the o r i g i n a l 0 content of l a t e •I Q hydrothermal f l u i d s a t Capoose from d 0 v a l u e s f o r p h y l l i c a l t e r a t i o n and quartz and c a l c i t e v e i n s gave v a l u e s r a n g i n g from -8.6 t o 1.8 ° / 0 0 - These v a l u e s r e p r e s e n t the e q u i l i b r a t i o n of hydrothermal f l u i d s w i t h w a l l r o c k o f s l i g h t l y h i g h e r 1 8 0 content. Thus, the o r i g i n a l i s o t o p i c composition must have been l e s s than d 0 = -8.6 / O Q . The • • 1 8 • • • i n i t i a l d x o 0 of meteoric waters p r i o r t o exchange w i t h 273 TABLE 4.18: C a l c u l a t e d water t o rock r a t i o s ( s e c t i o n 4.7.2) assuming an open system a t the Capoose pr o s p e c t , c e n t r a l B r i t i s h Columbia. SAMPLE dl80 dl80 W/R NUMBER WHOLE ROCK WATER OPEN SYSTEM GCP013 9.4 4.9 0.09 GCP018 7.9 3.4 0.29 KCP009 7.5 7.8 0.02 KCP012 8.0 8.3 0. 03 KCP028 5.4 5.7 0.06 KCP054 7.3 7.6 0. 01 274 w a l l r o c k i s best c a l c u l a t e d u s i n g D/H an a l y s e s o f waters e x t r a c t e d from s e r i c i t e and equation 4.6. Equation 4.6. INITIAL METEORIC WATER ( C r a i g , 1961): dD = 8 d 1 8 0 + 10 The dD v a l u e as measured from waters e x t r a c t e d from s e r i c i t e i s -155 ° / Q O (Table 4.18). The dD v a l u e f o r me t e o r i c water oo : B T.aVo a r e a f nHav l B a n n r n v i m a l - o l u — I f i f l ^ / OO i n the Capoose Lake area today i s approximately -160°/ ( f i g u r e 6.3 i n T a y l o r , 1979). T h i s meteoric i s o t o p e composition r e f l e c t s l a t i t u d e and e l e v a t i o n t h a t have not s i g n i f i c a n t l y changed s i n c e T e r t i a r y time. S i n c e oxygen i s o t o p i c compositions of meteoric waters have o n l y undergone a 1 t o 2% s h i f t toward h e a v i e r v a l u e s s i n c e T e r t i a r y time ( T a y l o r , 1974; O'Neil and Silberman, 1974), the -155 ° / O Q v a l u e determined e x p e r i m e n t a l l y from waters e x t r a c t e d from s e r i c i t e a t Capoose i s e s s e n t i a l l y e q u i v a l e n t . By u s i n g the dD v a l u e of -155 ° / Q O , the i n i t i a l d 1 8 0 of waters a t Capoose i s c a l c u l a t e d as -20.6 ° / 0 0 by equation 4.6. Assumming hydrothermal f l u i d s make o n l y one pass through an open system as evidenced by open space f i l l i n g t e x t u r e s ( s e c t i o n 4.6.1), the e a r l y water t o rock r a t i o s a t Capoose are 0.01 t o 0.29 c a l c u l a t e d from T a y l o r (1979). Equation 4.7. OPEN SYSTEM W/R (T a y l o r , 1979): w/r = In [" d-water + - d-rock _d xwater - (d f r o c k - A ) where A = d f r o c k - dfwater, and i = i n i t i a l v a l u e , and f = f i n a l v a l u e a f t e r exchange. 2 7 5 T h i s open system model g i v e s o n l y minimum water t o rock r a t i o s because (1) a l o t of water may pass through the rocks without e q u i l i b r a t i n g , and (2) the water e n t e r i n g the volume of rock under c o n s i d e r a t i o n c o u l d have become d e p l e t e d i n i p . . . 0 from the o r i g i n a l i s o t o p i c composition i t had b e f o r e e n t e r i n g the rock system (Sheppard, 1977). 4.7.2.7 I n t e r p r e t a t i o n The temperature of d e p o s i t i o n and i s o t o p i c composition of m i n e r a l i z i n g and p o s t - m i n e r a l i z i n g f l u i d s a t Capoose have been q u a n t i f i e d and the water t o rock o f p o s t -m i n e r a l i z i n g f l u i d s . D i s c u s s i o n of i s o t o p i c d e p l e t i o n , o r i g i n , and source of m i n e r a l i z a t i o n f o l l o w s t o g e t h e r w i t h comparison t o s i m i l a r d e p o s i t s i n B r i t i s h Columbia and elsewhere i n the world. M i n e r a l i z i n g f l u i d s a t Capoose d e p o s i t e d d i s s e m i n a t e d and f r a c t u r e c o n t r o l l e d s u l p h i d e s i n Late Cretaceous g a r n e t i f e r o u s r h y o l i t e s i l l s which show no d e p l e t i o n i n 0. Whole rock samples have d 1 8 0 of 5.4 t o 8.0 °/OQ, which exceeds the minimum d 1 8 0 of +5.5 f o r normal igneous rocks on the e a r t h ( T a y l o r , 1979). T h i s l a c k of d e p l e t i o n i s accompanied by low water t o rock r a t i o s o f 0.02 t o 0.11, which suggests t h a t the s i l l s had low p e r m e a b i l i t i e s . M i n e r a l i z e d zones are o v e r p r i n t e d by p e r v a s i v e s e r i c i t e a l t e r a t i o n which i s de p l e t e d i n 1 8 0 by 13.6 t o 15.6 ° / 0 0 . The d e p l e t i o n i s i n d i c a t i v e of a l t e r a t i o n o f w a l l r o c k by l a r g e volumes of low 1 8 0 content hydrothermal f l u i d s a t 276 e l e v a t e d temperatures. C a l c u l a t e d water t o rock r a t i o s f o r s e r i c i t e a l t e r e d zones are 0.38 which i s much h i g h e r than u n a l t e r e d zones i n the s i l l s . The hydrogen i s o t o p e composition, e x p e r i m e n t a l l y d e r i v e d from waters e x t r a c t e d from s e r i c i t e a t Capoose, must have o r i g i n a t e d from meteoric water with v i r t u a l l y no c o n t r i b u t i o n from magmatic or metamorphic sources ( F i g . 4.23). On F i g u r e 4.23, the p o s s i b l e range of d 1 8 0 d e p o s i t i o n a l f l u i d composition f o r s e r i c i t e i s p l o t t e d w i t h known dD v a l u e . OH-bearing minerals p r e s e r v e t h e i r dD v a l u e s d e s p i t e any l a t e r exchange wi t h heated groundwater ( H a l l e t a l . , 1974). Thus, the s e r i c i t e a t Capoose does appear t o have formed from heated meteoric waters. P o s t - m i n e r a l i z i n g f l u i d s d e p o s i t e d quartz and c a l c i t e v e i n s i n a n d e s i t e , d a c i t e and l i t h i c wacke of the Middle J u r a s s i c H a z e l t o n Group wi t h v i r t u a l l y no d e p l e t i o n of 1 8 0 . Whole rock samples have d 1 8 0 of 7.9 to 9.4 ° / 0 0 , which exceeds the minimum d x o 0 of +5.5 f o r normal igneous rocks on the e a r t h ( T a y l o r , 1968). V e i n samples are d e p l e t e d i n 1 8 0 by only 2.1 ° / Q O - Water t o rock c a l c u l a t i o n s f o r an open system g i v e low r a t i o s of 0.06 t o 0.14. The l a c k of e x t e n s i v e d e p l e t i o n and low water t o rock r a t i o s i s i n d i c a t i v e of o n l y minor a l t e r a t i o n of w a l l r o c k by s i m i l a r 1 R O content hydrothermal f l u i d s a t e l e v a t e d temperatures. The low degree of i s o t o p i c exchange i s i n t e r p r e t e d as incomplete s a t u r a t i o n of the host rocks w i t h hydrothermal f l u i d s . 2 7 7 -20 -60 --80 Q -100 -120 -140 - 6 0 -180 -200 METAMORPHIC WATERS PRIMARY MAGMATIC' WATERS 7*7 CosapoUa, Peru L ^ j ^ ^ - E l y , U.S.A. Climax, U.S.A. 4*jMfy J///Aw)?> \ cassiar District.B.C 10 IS 20 18. RANGE OF ISOTOPIC COMPOSITION OF FLUID ASSOCIATED WITH THE CAPOOSE ORE RANGE OF ISOTOPIC COMPOSITION OF FLUID ASSOCIATED WITH LATE SILICATE VEINING AND SERICITIZATION AT C A P O O S E F I G U R E 4 . 2 3 : dD v s . d 1 8 0 v a l u e s showing f i e l d s f o r magmatic and metamorphic water and the range o f d e p o s i t i o n of f l u i d composition a t Capoose, c e n t r a l B.C. Values f o r other w e l l known d e p o s i t s are a l s o shown. 278 C a l c u l a t e d oxygen isotope compositions and p o s t u l a t e d hydrogen i s o t o p e compositions f o r l a t e - f o r m e d quartz and c a l c i t e v e i n s a t Capoose probably o r i g i n a t e d from meteoric water with v i r t u a l l y no c o n t r i b u t i o n from magmatic or metamorphic sources ( F i g . 4.23). On F i g u r e 4.23, the range of d o d e p o s i t i o n a l f l u i d composition i s p l o t t e d t o g e t h e r w i t h the p o s t u l a t e d dD v a l u e estimated i n s e c t i o n 4.7.2.6. These v e i n s are comparable with those i n the C a s s i a r D i s t r i c t of n o r t h e r n B.C. ( N e s b i t t e t a l . , 1985), Climax and E l y , U.S.A., and Casapalca, Peru ( T a y l o r , 1979). Oxygen i s o t o p e compositions of u n a l t e r e d whole rock samples from the m i n e r a l i z e d r h y o l i t e s i l l s are d i s t i n c t l y d i f f e r e n t from the d e p l e t e d oxygen i s o t o p e compositions of s e r i c i t e a l t e r e d samples, which suggests two sources of water f o r the d e p o s i t . These i s o t o p i c r e l a t i o n s h i p s are s i m i l a r t o those i n porphyry copper and molybdenum d e p o s i t s where both magmatic-hydrothermal and meteoric-hydrothermal systems are s i m u l t a n e o u s l y present e a r l y i n the h i s t o r y of a porphyry s t o c k ( T a y l o r , 1979). With time and c o o l i n g of the stock, the meteoric-hydrothermal system a c t i n g o u t s i d e the i n t e r n a l porphyry system c o l l a p s e s onto the c o o l e d h y d r o t h e r m a l l y a l t e r e d rocks formed by magmatic s o l u t i o n s . S e r i c i t e a l t e r a t i o n zones w i l l then be l o c a l l y superimposed upon the f r e s h i n t r u s i v e ( T a y l o r , 1979). M i n e r a l i z a t i o n i n r h y o l i t e s i l l s a t Capoose a p p a r e n t l y formed a t magmatic temperatures of 528°C t o 725°C ( s e c t i o n 4.7.2.3) from primary magmatic waters with d x o 0 r a n g i n g from 5.7 to 8.3 ° / 0 0 ( F i g . 4.23). S e r i c i t e a l t e r e d zones formed by l o c a l s u p e r i m p o s i t i o n of e x t e r n a l meteoric-hydrothermal waters with d 1 8 0 ranging from -8.6 to -6.6 ° / O Q and a dD of "155 ° / O D . The source o f m i n e r a l i z a t i o n i n the system i s the s i l l s themselves which were i n j e c t e d i n t o H a z e l t o n Group rocks ( s e c t i o n 2.2) d u r i n g l a t e stages o f c r y s t a l l i z a t i o n ( s e c t i o n 4.5) i n the upper, i n t e r i o r p o r t i o n s of, probably, the Capoose b a t h o l i t h . The Capoose d e p o s i t i s i s o t o p i c a l l y comparable with the E l y and Climax d e p o s i t s i n the Western U.S.A. ( F i g . 4.23; T a y l o r , 1979). 4.8 CONCLUSIONS 4.8.1 ORIGIN The Capoose p r e c i o u s and base metal p r o s p e c t occurs i n Upper Cretaceous g a r n e t i f e r o u s r h y o l i t e s i l l s which i n t r u d e E a r l y t o Middle J u r a s s i c Hazelton Group rocks i n c e n t r a l B r i t i s h Columbia ( F i g . 2.1). The Hazelton Group (Leech, 1910) r e p r e s e n t s widespread c o n t i n e n t a l t o i s l a n d - a r c v o l c a n i c and sedimentary d e p o s i t s accumulated i n the Hazelton trough from Sinemurian t o e a r l y C a l l o v i a n time (Tipper and Richards, 1976). At Capoose, the Middle J u r a s s i c s u c c e s s i o n i s i n f a u l t c o n t a c t w i t h Lower J u r a s s i c rocks t o the nort h and south (Tipper e t a l , 1974) and appears t o be preserved as a b l o c k - f a u l t e d e r o s i o n a l remnant. Upper Cretaceous r h y o l i t e s i l l s , i n t r u s i v e i n t o the J u r a s s i c s u c c e s s i o n , have been d e s c r i b e d by Church (1972) i n the Buck Creek area, which i s 100 km n o r t h -280 northwest of Capoose. However, the occurrence o f garnet i n the s i l l s a t Capoose i s unique. Hazelton Group rocks occur as mafic v o l c a n i c , v o l c a n i c l a s t i c and sedimentary rocks i n the v i c i n i t y of the Capoose p r o s p e c t (Andrew and Godwin, 1987). The mafic v o l c a n i c rocks are t y p i c a l l y massive and l o c a l l y s c o r i a c e o u s b a s a l t i c - a n d e s i t e flows. On the b a s i s o f l i t h o l o g i c s i m i l a r i t y , these rocks might r e p r e s e n t a d i s t a l f a c i e s t o the subaqueous v o l c a n i c s of the e a r l y J u r a s s i c Ankwell member of the N i l k i t k w a Formation d e s c r i b e d by T i p p e r and Richards (1976). V o l c a n i c and sedimentary r o c k s l i e conformably above the b a s a l t i c a n d e s i t e s and c o n s i s t o f f e l s i c l a p i l l i t u f f s interbedded with d a c i t e flows, a r g i l l i t e and l i t h i c wacke. V o l c a n i c a c t i v i t y o c c u r r e d contemporaneously with shallow marine s e d i m e n t a t i o n . The h i g h p r o p o r t i o n of angular f e l d s p a r and rock fragments i n wacke beds i n d i c a t e s r a p i d sedimentation and a nearby source. From l i t h o l o g i c and f o s s i l evidence ( s e c t i o n 4.4), these rocks are c o r r e l a t e d with the Yuen member of the Smithers Formation. A r e g i o n a l compressional t e c t o n i c event i n Upper J u r a s s i c and Lower Cretaceous time (Tipper, 1963) was accompanied by f o l d i n g and probable u p l i f t o f Fawnie Range. A p e r i o d of e r o s i o n from Lower t o Upper Cretaceous time was f o l l o w e d by emplacement of l a r g e g r a n i t i c i n t r u s i o n s such as the Capoose b a t h o l i t h ( F i g . 2.1). 281 R h y o l i t e s i l l s occur as a sequence o f 10 t o 400 m t h i c k , flow-banded, s p h e r u l i t i c , g a r n e t i f e r o u s quartz r h y o l i t e and r h y o l i t e i n t r u s i o n s d i p p i n g approximately 30° to the southwest. An igneous o r i g i n f o r the garnets i s i n d i c a t e d by microprobe s t u d i e s of garnet composition and zoning. The garnets are s p e s s a r t i n e - r i c h ( > s p 6 0) and c r y s t a l l i z e d as l a t e phase phenocrysts s t a b i l i z e d by h i g h Mn i n a d i f f e r e n t i a t e d magma ( s e c t i o n 4.5). Oxygen i s o t o p e compositions o f quartz-garnet m i n e r a l s e p a r a t e p a i r s were used t o c a l c u l a t e the temperature of d e p o s i t i o n of the s i l l s ( s e c t i o n 4.7). Temperatures of formation o f 528°C t o 725°C c o n f i r m t h a t the garnets are magmatic i n o r i g i n . The occurrence of igneous garnets a t Capoose i s unusual because no other documentation o f primary g a r n e t i f e r o u s r h y o l i t e s i l l s has been r e p o r t e d i n the Mesozoic o r Cenozoic l i t e r a t u r e i n B r i t i s h Columbia. The metaluminous Capoose b a t h o l i t h i s c o e v a l with the s i l l s and has excess aluminum to enhance garnet s t a b i l i t y . I t i s proposed as a p o t e n t i a l parent magma f o r r h y o l i t e s i l l s a t Capoose. E x t e n s i o n a l t e c t o n i c s accompanied by b l o c k f a u l t i n g and a s s o c i a t e d v o l c a n i s m took p l a c e i n e a r l y T e r t i a r y time (Tipper, 1963). Mid-Eocene Ootsa Lake Group rocks were unconformably d e p o s i t e d on the Hazelton Group. Ho r s t and graben s t r u c t u r e s were developed on Fawnie Range ( F i g . 4.2, s e c t i o n 4.2) and throughout the Capoose Lake area ( s e c t i o n 3.2) . 282 4.8.2 DEPOSIT MODEL The model proposed f o r the Capoose p r e c i o u s and base metal prospect i s d e p i c t e d i n F i g u r e 4.24. G e o l o g i c s e t t i n g , m i n e r a l i z a t i o n , a l t e r a t i o n and metal d i s t r i b u t i o n most c l o s e l y resembles a low-grade, e p i g e n e t i c , i n t r u s i o n -r e l a t e d , p o r p h y r y - s t y l e d e p o s i t (McMillan and Panteleyev, 1980; T i t l e y and Beane, 1981; T i t l e y , 1982). The emplacement of r h y o l i t e s i l l s i n groundwater s a t u r a t e d permeable Hazelton Group rocks, f o l l o w e d by c o o l i n g , c r y s t a l l i z a t i o n and f r a c t u r e development, c o u l d have i n i t i a t e d hydrothermal c i r c u l a t i o n . The hydrothermal system r e s u l t e d i n development of p e r v a s i v e s e r i c i t e a l t e r a t i o n , f o l l o w e d by l a t e quartz and c a l c i t e v e i n i n g p e r i p h e r a l t o the i n t r u s i o n r e l a t e d t o c o l l a p s e of the hydrothermal system. M i n e r a l i z a t i o n hosted i n r h y o l i t e s i l l s a t Capoose i s t y p i f i e d by p y r i t e , s p h a l e r i t e , galena, c h a l c o p y r i t e and a r s e n o p y r i t e o c c u r r i n g mainly as d i s s e m i n a t i o n s and a l s o as f r a c t u r e f i l l i n g s . P r e c i o u s metal b e a r i n g m i n e r a l s occur as i n c l u s i o n s w i t h i n the dominant s u l p h i d e s (Schroeter, 1981). Frequently, anhedral brown garnet aggregates occur i n c l o s e a s s o c i a t i o n t o s u l p h i d e accumulations. T h i s a s s o c i a t i o n i n d i c a t e s t h a t the garnets c o u l d have p r o v i d e d a nucleus f o r s u l p h i d e d e p o s i t i o n . Sulphide and garnet accumulations are commonly surrounded by f i n e - g r a i n e d muscovite and quartz coronas up t o 5 mm i n width. I n t r u s i o n of r h y o l i t e s i l l s and subsequent f r a c t u r i n g of s i l l s and c o u n t r y rock p r o v i d e d 283 1 MAGMATIC - Garnet and sulphide deposition > paleosurface__ garnet and sulphides ^ Hazelton 1 Group ^ ^ ^ ^ ^ / " 2 k r " / ' ^ / ^ V x ^ ' ' ' ^ s i l l s / X t j ^ ^ y y ^ y / at Capoose i + ^ + + v hornfels magmatic / + Capoose + + r \ v , fluid / + + batholith + + + 4 km ^ 7 5 km 2 METEORIC -sericitization of sills, si l icate veining paleosurface / \ W ' X ~ \ — \ quartz and \ \ ^ v calcite veins meteoric v ^ C ^ r ^ & & ^ \ \ \ fluid ^ y ^ < ^ 0 ^ \ \ J / ^ I ( ^ v ^ V ^ O ^ ^ v ^ ^ / meteoric -2 km ^ = ^ p > < ^ ^ f , u l d ' / h 4- + + sericite V ~ T _ - r ^ - ^ h o « ' " f e l s +- alteration + 4- + v 4 km ^ >-5 km 1 FIGURE 4.24: Low-grade, e p i g e n e t i c , i n t r u s i o n - r e l a t e d , porphyry-s t y l e model f o r genesis of the Capoose pr o s p e c t , c e n t r a l B r i t i s h Columbia. 284 c o n d u i t s f o r c i r c u l a t i n g hydrothermal f l u i d s . M i n e r a l d e p o s i t i o n must have occurred at shallow depths of l e s s than 5 km i n order t o maintain these open f r a c t u r e s . Although s i l i c a t e v e i n i n g i s n o t a b l y absent w i t h i n the s i l l s , quartz and c a l c i t e v e i n s with minor p y r i t e occur i n h o r n f e l s e d Hazelton Group rocks adjacent to the s i l l s . These v e i n s were emplaced l a t e i n the hydrothermal system and d i s p l a y open space f i l l i n g t e x t u r e s . Metal d i s t r i b u t i o n graphs and c o r r e l a t i o n m a t r i c i e s a l s o i n d i c a t e l e a d and z i n c p o p u l a t i o n s i n the Hazelton Group. Hydrothermal f l u i d s a s s o c i a t e d with i n t r u s i o n of the r h y o l i t e s i l l s d e p o s i t e d anomalous l e a d , z i n c , copper and s i l v e r ( s e c t i o n 4.6.3). Zones of p h y l l i c a l t e r a t i o n r e s t r i c t e d t o the r h y o l i t e s i l l s o v e r p r i n t m i n e r a l i z e d zones a t Capoose. F l u i d i n c l u s i o n s t u d i e s of p o s t - m i n e r a l i z i n g v e i n s p e r i p h e r a l t o the s i l l s i n d i c a t e t h a t l a t e p r e c i o u s - m e t a l poor hydrothermal f l u i d s were c h a r a c t e r i z e d by homogenization temperatures from 285°C t o 335°C and s a l i n i t i e s o f approximately 1 weight p e r c e n t NaCl. These h i g h homogenization temperatures support the presence of r h y o l i t e s i l l s which s u p p l i e d thermal energy t o d r i v e the hydrothermal c i r c u l a t i o n . Depths of emplacement were c a l c u l a t e d u s i n g equations developed by Haas (1971) assumming the f l u i d s were b o i l i n g . C o n s i d e r i n g c o n d i t i o n s i n t e r m e d i a t e between h y d r o s t a t i c and l i t h o s t a t i c , l a t e quartz and c a l c i t e v e i n s d e p o s i t e d a t depths from 340 m t o 285 1140 m. These c a l c u l a t e d depths are expected f o r shallow open-space f i l l e d v e i n s . S t a b l e i s o t o p e compositions of r h y o l i t e s i l l s a t Capoose i n d i c a t e t h a t v i r t u a l l y no i s o t o p i c exchange has taken p l a c e between w a l l r o c k and Upper Cretaceous or e a r l y • 1 8 T e r t i a r y low x o 0 content hydrothermal f l u i d s ( s e c t i o n 4.7.2.5). F l u i d s which p r e c i p i t a t e d the g a r n e t s and s u l p h i d e s , are assumed to be i n i s o t o p i c e q u i l i b r i u m w i t h the a s s o c i a t e d magmatic r h y o l i t e s i l l s . C a l c u l a t e d temperatures of formation of the s i l l s u s i n g quartz and garnet m i n e r a l separates g i v e probable magmatic temperatures of 528°C t o 72 5°C. Hydrogen and oxygen i s o t o p i c compositions on s e r i c i t e i n subsequent p h y l l i c a l t e r a t i o n suggests the presence of evolved meteoric water ( s e c t i o n 4.7.2.5). Oxygen i s o t o p e evidence a l s o shows t h a t low s a l i n i t y meteoric hydrothermal s o l u t i o n s formed quartz and c a l c i t e v e i n s p e r i p h e r a l t o the s i l l s a t 285°C t o 335°C. T h i s sequence of f l u i d e v o l u t i o n from e a r l y , h i g h temperature magmatic f l u i d s t o l a t e meteoric-hydrothermal f l u i d s has been found r e p e a t e d l y i n i s o t o p i c s t u d i e s of porphyry d e p o s i t s ( T a y l o r , 1979). The s i z e of the m e t e o r i c -hydrothermal c i r c u l a t i o n c e l l a t Capoose i s p r e d i c t e d by water t o rock r a t i o s which i n d i c a t e t h a t f o r every gram of rock i n the area of the prospect, a t l e a s t 0.06 t o 0.14 grams of water have moved through the system. C o n s e r v a t i v e l y , assuming an a l t e r e d area o f 2 km 2 t o a depth 286 of 350 m, the minimum amount of water t h a t must have passed through 50 percent of these rocks i s 5.67 * 1 0 1 0 k g 3 . The source of m i n e r a l i z a t i o n a t Capoose i s the r h y o l i t e s i l l s a t Capoose ( s e c t i o n 4.6 and 4.7). The e x t e n t of meteoric water c i r c u l a t i o n on the p r o p e r t y i s taken as s u p p o r t i v e evidence f o r the c o n v e c t i v e model of M c M i l l a n and Panteleyev (1980) i n which the c o o l i n g s i l l s s upply the heat r e q u i r e d f o r c i r c u l a t i o n and l e a c h i n g of metals. The Capoose d e p o s i t i s i s o t o p i c a l l y comparable w i t h the E l y , Climax, and Butte d e p o s i t s i n southwestern U.S.A. ( F i g . 4.25, T a y l o r , 1979; 1987). F i e l d evidence, l a b o r a t o r y s t u d i e s and t h e o r e t i c a l c o n s i d e r a t i o n s suggest t h a t emplacement o f the s i l l s a t Capoose a t a magmatic temperature of about 642°C i n i t i a t e d c o n v e c t i v e hydrothermal c i r c u l a t i o n . S i n c e the s i l l s had low p e r m e a b i l i t i e s (w/r < 0.1), e a r l y d e p o s i t i o n of s u l p h i d e s and a s s o c i a t e d p r e c i o u s metals was mainly disseminated. With time and c o o l i n g of the s i l l s , s u l p h i d e s were a l s o d e p o s i t e d as f r a c t u r e f i l l i n g s . Thermal c o l l a p s e of the meteoric hydrothermal system on c o o l e d h y d r o t h e r m a l l y a l t e r e d rocks formed by magmatic s o l u t i o n s o c c u r r e d a t lower temperatures from 285°C t o 335°C. S e r i c i t e a l t e r a t i o n zones were l o c a l l y superimposed on the r h y o l i t e , and q u a r t z and c a l c i t e v e i n s developed p e r i p h e r a l l y t o the s i l l s . 287 CHAPTER 5 CONSEQUENCES OF DEPOSIT MODELLING IN THE CAPOOSE LAKE AREA The Capoose Lake area encompasses s i g n i f i c a n t p r e c i o u s metal d e p o s i t s of d i f f e r e n t tenor — the Wolf e p i t h e r m a l p r o s p e c t hosted i n Eocene f e l s i c v o l c a n i c rocks and the Capoose p o r p h y r y - s t y l e prospect hosted i n Upper Cretaceous g a r n e t i f e r o u s r h y o l i t e s i l l s . M i n e r a l p o t e n t i a l i n the area i s enhanced by: (1) s u i t a b l e ground p r e p a r a t i o n i n the form of s t r u c t u r e s such as b l o c k f a u l t s , and (2) heat sources i n the form of b a t h o l i t h s , stocks and s i l l s which c o n t r o l f l u i d c o n v e c t i o n and focus hydrothermal d i s c h a r g e . Ootsa Lake Group s t r a t i g r a p h y i n the Capoose Lake area has been mapped i n d e t a i l , c o r r e l a t e d w i t h exposures near W h i t e s a i l Lake (Diakow and Mihalynuk, 1987), c h e m i c a l l y c l a s s i f i e d as r h y o l i t e s of c a l c - a l k a l i n e a f f i n i t y , and dated as mid-Eocene (L u t e t i a n ) by whole rock K-Ar. D e p o s i t i o n o f p r e c i o u s metal b e a r i n g quartz v e i n s and b r e c c i a s i n the v i c i n i t y o f the Wolf prospect r e p r e s e n t s the o n l y documented occurrence of epithermal m i n e r a l i z a t i o n w i t h i n Ootsa Lake Group f e l s i c v o l c a n i c r o c k s . Although e p i t h e r m a l - t y p e m i n e r a l i z a t i o n hosted i n mafic v o l c a n i c s o f the Ootsa Lake Group (?) has been d e s c r i b e d a t the Trout Lake p r o s p e c t , 55 km northwest of Wolf, no s i g n i f i c a n t m i n e r a l i z a t i o n has been documented i n e q u i v a l e n t rocks on the W h i t e s a i l Lake sheet (Diakow, o r a l comm. 1988). Lower t o middle J u r a s s i c Hazelton Group s t r a t i g r a p h y i n the v i c i n i t y o f the Capoose prospect has been mapped i n 288 d e t a i l and c o r r e l a t e d with the N i l k i t k w a and Smithers Formations of T i p p e r and Richards (1976) i n the Smithers area. These mafic v o l c a n i c , v o l c a n i c l a s t i c and sedimentary rocks are i n t r u d e d by Upper Cretaceous ( M a a s t r i c h t i a n ) c a l c -a l k a l i n e , g a r n e t i f e r o u s r h y o l i t e s i l l s on Fawnie Range ( F i g . 2.1). These s i l l s are c o e v a l with the Capoose b a t h o l i t h , a quartz monzonite p l u t o n i n the Capoose Lake a r e a . Microprobe and oxygen i s o t o p e work has e s t a b l i s h e d t h a t the garnets w i t h i n the s i l l s are of igneous o r i g i n and p r e c i p i t a t e d as l a t e phase phenocrysts s t a b i l i z e d by h i g h Mn i n a d i f f e r e n t i a t e d magma. The occurrence of igneous garnets a t Capoose i s unusual because no o t h e r documentation of primary g a r n e t i f e r o u s r h y o l i t e s i l l s has been r e p o r t e d i n the Mesozoic or Cenozoic l i t e r a t u r e i n B r i t i s h Columbia. P r e c i o u s metals occur as i n c l u s i o n s w i t h i n d i s s e m i n a t e d and v e i n base-metal s u l p h i d e s . Sulphides and g a r n e t s are c l o s e l y a s s o c i a t e d i n m i n e r a l i z e d zones o v e r p r i n t e d by p e r v a s i v e s e r i c i t e a l t e r a t i o n . The d e p o s i t i o n a l environment at Capoose most c l o s e l y resembles a low-grade, e p i g e n e t i c , i n t r u s i o n - r e l a t e d , porphyry d e p o s i t ; however, the predominantly disseminated m i n e r a l i z a t i o n s t y l e , c l o s e a s s o c i a t i o n with s p e s s a r t i n e - r i c h garnets, and n o t a b l e absence of s i l i c a t e v e i n s i n the s i l l s a re unique. The occurrence of s i g n i f i c a n t p r e c i o u s - m e t a l d e p o s i t s i n the Capoose Lake area demonstrates the p o t e n t i a l f o r s u c c e s s f u l m i n e r a l e x p l o r a t i o n i n Mesozoic and Cenozoic a r c -r e l a t e d rocks w i t h i n the Nechako P l a t e a u . D e s p i t e e x t e n s i v e 289 overburden, rock types i n the area are r e a d i l y d i v i s i b l e i n t o mappable u n i t s . The u n i t s can be c o r r e l a t e d w i t h type s e c t i o n s i n b e t t e r exposed areas. Although access t o the area p r e v i o u s l y hampered e x p l o r a t i o n a c t i v i t y , c o n s t r u c t i o n of f o r e s t r y and mining roads i n r e c e n t years has opened up the area and spurred renewed i n t e r e s t i n c e n t r a l B r i t i s h Columbia. 290 REFERENCES Armstrong, J.E. (1944): Smithers, B r i t i s h Columbia. G e o l o g i c a l Survey of Canada, Paper 44-23. Andrew, K.P.E., Godwin, C.I, and Cann, R.M. 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C o n t r i b u t i o n s t o Mineralogy and P e t r o l o g y , V o l . 26, pp. 225-246. APPENDIX 1 ROCK SAMPLES USED IN THIS STUDY SAMPLE # THIN SECTION POLISHED SECTION WHOLE ROCK ANALYSIS MICROPROBE ANALYSIS FLUID INCLUSION PALYNOL. SECTION ISOTOPE ANALYSIS K-AR PB 0 H WOLF PROSPECT E o l KA109AP X - - - - - - - - -KA109AN X - - - - - - - - -KA109GD X - - - - - - - - -KA109MA X - - - - - - - - -Eo2 KA106 X - X - - - - - -KA108 X - X - - - - - - -KA162 X - - - - - - - - -Eo3 KA067 X - X - - - - - - -KA213 X - - - - - - - - -Eo4 KA029 X - X - - - - - - -KA090 X - X - - - - - - -Eo5 KA077 X - X - - - - - - -KA078 X - X - - - - - X -Eo6 KA133 X - X - - - - - - -KA135 X - X - - X - - X -Eo7 KA009 X - X - - - - - - -KA035 X - - - - - - - - -KA104 X - X - - - - - - -KA112 X - X - - X - - X -Eo8 KA059 X - - - - - - - - -KA091 X — — — — — — — — — o APPENDIX 1 (continued p2.) ROCK SAMPLES USED IN THIS STUDY SAMPLE # THIN SECTION POLISHED SECTION WHOLE ROCK ANALYSIS MICROPROBE ANALYSIS FLUID INCLUSION PALYNOL. SECTION ISOTOPE ANALYSIS K-AR PB 0 H WOLF PROSPECT Eo9 KA066 X - X - - - - - - -KA078 X - X - - X - - - -KA128 X - X - - - - - X -KA147 X - - - - - - - - -KA163 X - - - - - - - -KA175 X - - - - - - - -KA180 X - - - - - - - - -KA184 X - X - - - - - - -KA221 X - X - - - - - - -EolO KA124 X - - - - - - - - -KA140 X - - - - - - - - -KA141 X - X - - - - - - -KA146 X - - - - - - - - -KA151 X - - - - - - - - -KA177 X - - - - - - - - -Jha KA178 X - X - - - - - X -KA185 X - - - - - - - - -KA195 • X - X - - - - - -KA200 X - X - - - - - - -KA203 X - - - - - - - - -KA220 X - X - - - - - - -Ms KA1-11 X - - - - X - - - -KA5-15 X - - - - X - - - -KA5-10 X - - - - X - - - -KA5-20 X - - - - X - - - -APPENDIX 1 (continued p3.) ROCK SAMPLES USED IN THIS STUDY SAMPLE # THIN SECTION POLISHED SECTION WHOLE ROCK ANALYSIS MICROPROBE ANALYSIS FLUID INCLUSION PALYNOL. SECTION ISOTOPE ANALYSIS K-AR PB O H WOLF PROSPECT V e i n KATR9-1 - - - - X - - - X X KA1-1 - - - - X - - - - -KA1-2 - - - - X - - - - -KA2-2 - - - - X - - - X -KA3-4 - - - - X - - - X -KA5-5 - - - - X - - - -KA022 - - - - X - - - X X KA4-8 - - - - X - - - X -KA4-15 - - - - X - - - - -KA4-19 - - - - X - - - - -KA6-2 - - - - X - - - X -KA6-14 - - - - X - - - - -KA019 - - - - X - - - - -KA031 - - - - X - - - - -KA063 - - - - X - - - - -KA111 - - - - X - - - X -KA188 — — — — X — — — X X CAPOOSE PROSPECT • • u n i t 1 GCP018 X - X - - - - - X -GCP02 0A X - - - - - - - - -KCP04 3 X - - - - - - - - -u n i t 2 KCP004 X — — — — — — — — — APPENDIX 1 (c o n t i n u e d p4.) ROCK SAMPLES USED IN THIS STUDY SAMPLE # THIN SECTION POLISHED SECTION WHOLE ROCK ANALYSIS MICROPROBE ANALYSIS FLUID INCLUSION PALYNOL. SECTION ISOTOPE ANALYSIS K-AR PB 0 H CAPOOSE PROSPECT u n i t 3 GCP013 X - X - - - - - X -u n i t 4 KCP018 X - - - - - - - - -GCP027 X - - - - - - - - -KDC144 X - - - - - - - - -KDC14 6 X - - - - - - - - -KDC170 X - - - - - - - - -u n i t 5 KCP002A X - X - - - - - - -GCP011 X - - - - - - - - -KDC111 X - - - - - - - - -u n i t 6 KCP009 X - X X- - - X - X -KCP028 X - X - - - - - X -KDC084 X - - - - - - - - -KDC170 X - - - - - - - - -u n i t 7 X KCP012 X - X X- - - - - X -KDC096 X — — — — — — — — — o APPENDIX 1 (continued p5 . ) ROCK SAMPLES USED IN THIS STUDY SAMPLE # THIN SECTION POLISHED SECTION WHOLE ROCK ANALYSIS MICROPROBE ANALYSIS FLUID INCLUSION PALYNOL. SECTION ISOTOPE ANALYSIS K-AR PB 0 H CAPOOSE PROSPECT u n i t 8 KCP037A X - - - - - - - - -KCP044 X - X - - - - - - -KCP054 X - X X - - - - X -KDC50-41 X - - - - - - X - -KDC001 X - - - - - - - - -KDC036A X - - - - - - - -KDC104 X - - - - - - - - -KDC173 X - - - - - - - - -KAD042 X - X - - - X - X X CAP-5-210 - X - - - - - - - -79CAP-4-5 04 X - - - - - - - -CAP-5-434 - X - - - - - - - -79CAP-6-2 60 X - - - - - - - -CAP80-39 - X - - - - - - - -u n i t 9 KCP028 X - X - - - - - - -KDC074 X - X - - - - - - -KDC163 X - - - - - - - - -u n i t l O KCP035 X - X - - - X - X -KCP049 X - - - - - - - -capoose b a t h o l i t h DVL190 X - X - - - X - - -v e i n s KDC040 - - - - X - - - X -KDC114 — — — — X — — — X — 306 APPENDIX 2A WHOLE ROCK ANALYSES: MAJOR ELEMENT OXIDES AND TRACE ELEMENTS V s r . M C : KA 009 KA 029 KA 066 KA 067 KA 077A KA 077B SI02 77 .89 73.57 74.21 70 ,20 76 . 05 7 6.33 AL203 11.01 11 .65 14.41 15.64 12.10 . 12.34 TI02 0 ,22 0.09 0 ,36 0 .55 0.20 0.20 FE203 1 . 59 0.73 0.96 1 .73 1,73 1 . 73 MGO 0 . 00 0 .04 0.02 0.07 0.01 0 . 00 CAO 0.10 0,15 0.17 0.15 0. 10 0.10 NA20 2 . 95 2 ,25 2.97 3 .23 3,23 K20 4.45 5.32 6.13 6.90 4 .31 4 . 37 MNO 0.00 0,00 0.01 0 . 00 0.02 0 , 02 P205 0 . 02 0.01 0.02 0.10 0 . 00 0 . 00 LOI 0 . 79 0 , 67 0,73 0 . 97 0 .43 0,5:: T c t s l 99 . 04 n r\ cr . 7 7 , *j -t 100.05 99 . 65 93.70 100 , 0 2 AG 0 0 o o 0 AS 12 11 15 20 i 7 BA 50 47 2 61 533 2 4 CL 0 0 9 0 0 0 r . -» <—i 7 15 0 3 NB 21 12 16 10 2 4 NI 0 3 0 2 7 0 RB 1 :~ 9 e- -> 204 i. 7 C 4. ~ Z 1 0 9 - L O I 6 3 6-' SB '-> 1 4 1 SE 0 0 0 0 0 0 SR 4 33 54 49 4 TE 0 0 0 0 0 0 U 7 4 o 6 V 10 i i 13 24 "7 4 Y 65 59 41 79 3 0 ZR 565 49 456 330 5 9 2 5 37 Major element o x i d e s i n % Trace elements i n ppm Analyzed by M i d l a n d E a r t h S c i e n c e A s s o c i a t e s , Nottingham, U.K. 3 0 7 APPENDIX 2A WHOLE ROCK ANALYSES: MAJOR ELEMENT OXIDES AND TRACE ELEMENTS (p.2) K A 073 K A 037 K A _ 0 9 0 ~ K A 104 KA~To~6 ~KTTO~8 SI02 7 6 . 46 76.37 79.40 79 . 32 73.11 65 .22 AL203 12.14 12 . 56 11 .31 10.91 12.31 15.27 TI02 0.21 0.23 0.12 0.14 0 .13 0 .34 FE203 1 . 42 0 .57 1 .01 1 .50 4 .30 M G O 0.02 0.04 0.03 0 ,03 0.24 1 . 60 C A O 0 .13 0,11 0.12 0.11 0.15 NA20 3.33 2.13 0.33 0,11 0.09 3.09 K2Q 4.62 6.17 6,0 4 7 .17 5.39 4.13 M N O 0 .02 0.02 0.00 0 ,00 0.04 0.16 P205 0 . 00 0.01 0 . 00 0 . 00 0 . 00 0 , 25 LOI 0 . 44 0.76 0 .30 0,53 1 ,93 1 . 7 9 Tots! 99 .26 100.32 93.79 99.90 9 9,94 99 , 66 AG 0 0 0 0 0 AS 10 15 14 32 1 1 t. BA *-\ cr J 79 500 63 163 97 4 CL 0 0 0 3 CR 12 r\ O 10 7 10 NS ^ T i_ _> 1 O X \J 3 n "i cr HI 0 0 n 3 A r' 20 1 ~r Ci ~r 7 23 4 1 4 6 :7 cr t 144 7 2 9 3 SB T 4 3 SE 0 0 0 0 0 0 3R L 11 45 cr "7 16 296 TE 0 1 0 0 0 0 U 4 6 c- 1 3 V 7 11 11 3 15 53 Y 33 72 IS 40 51 29 ZR 600 • 564 34 256 143 Major element o x i d e s i n % Trace elements i n ppm Analyzed by Midland E a r t h S c i e n c e A s s o c i a t e s , Nottingham, U.K. APPENDIX 2A WHOLE ROCK ANALYSES: MAJOR ELEMENT OXIDES AND TRACE ELEMENTS (p. 3) V3P.MD! KA 112 KA 12S KA 133 KA 135 KA 141 KA 163 SI02 30.45 j n n 4 73 . 02 . 15 3 0 . 42 74 .65 AL203 10.73 14.97 13 .23 14 . 05 1 0 . 2 14.77 TI02 0.15 0 .43 0 .23 0 .36 0 .13 0.10 FE203 0.80 1 ,27 1 . 75 1 .S7 1 .31 1.41 MGO 0.00 0 .00 0 .14 0 .03 0 .06 0.13 Cf.O 0.11 0.14 0 . 18 0 .19 0 .12 0.15 NA20 0.92 0.31 3 .44 3 ,60 0 . 14 1 .48 K20 6 . 00 S.91 >J . 23 6 . J, ^  C -? o 6.00 MNO 0.00 0 .02 0 .04 0 .03 0 .02 0.0 5 P205 0.00 0 .03 0 .04 0 . 09 0 . 0 2 0,00 LOI 0 .69 0.92 0 .63 0 . 34 1 . 19 1.16 Tots 1 09 . 36 9? .79 9 7 .98 1 J0 » i i 99 A G 0 0 0 Q 0 Q A3 43 10 4 7 42 7 BA 42 46 3 155 263 4 6 7 O CL 0 7 0 0 I J CF; 10 4 4 r. 1 2 i i MB 10 14 1 3 '2 2 N I n i "7 0 F, ? o r. 3 6 7 2 0 0 ^ *' "7 2 o 9 130 7 7 7 9 4 3 SB L 0 TT 0 •~i o SE 0 0 0 0 0 0 SR 11 77 1 1 29 20 13 TE 0 0 0 0 0 0 U 6 4 4 4 6 y cr 13 16 14 4 Y 61 43 54 43 71 36 320 •314 400 377 343 134 ========= ============== ======= ======== ======== ==== : = = = = = = ===== ==== = = = = = = = = = = : Major element o x i d e s i n % Trace elements i n ppm Analyzed by Mi d l a n d E a r t h S c i e n c e A s s o c i a t e s , Nottingham, U.K. 309 APPENDIX 2A WHOLE ROCK ANALYSES : MAJOR ELEMENT OXIDES AND TRACE ELEMENTS (p. 4) VSP.MD! KA 173 KA 134 KA 195 KA 200A KA 200B K A 220 SI02 46.92 76.37 43.21 75.73 76.45 76.34 AL203 14.33 11 .79 11 .43 13.54 13 .20 12.36 TI02 0 . 77 0.14 0 . 66 0,24 0 . 23 0.09 FE203 10.97 1 .31 3.27 2.55 2.46 0.76 MGO 3.51 0 . 07 11 .97 0.35 0 . 33 0.00 C A O 9 . 96 0.27 10.24 0.21 0 .20 0.13 NA20 1.79 3 .36 1 .72 1 .27 1 .23 0 . 47 K20 0.92 4 . 70 0.53 4 ,26 4 .08 S. 11 MNO 0 . 22 0.02 0.15 0.06 0.06 0,00 P205 0 . 32 0 . 02 0.13 0 . 04 0 . 04 0.02 LOI 0.52 "7 - 1,31 1 . 90 0 .64 T c t s l 7 O • 4 7 9 9.07 9 9,15 100.12 100 .23 99.43 A G 1 X 0 0 0 0 A S ") 10 4 1 1 12 21 T O 1 cr cr 4 62 I — I S 5 CL 35 0 0 0 0 7 p •-• i 5 3 6 o P. 0 N B 16 0 21 2 1 1 i . N : 0 146 n -7 cr ^ _ 123 " 7 3 114 ?4 9 7 -I 3 i ss 0 0 0 X 0 0 0 SR 686 75 394 34 34 42 Tc 0 0 0 0 3 0 U 0 e* 0 6 6 5 y 344 12 137 15 17 7 Y 33 T n 33 31 23 Z R 33 • 146 54 500 501 66 Major element o x i d e s i n % Trace elements i n ppm Analyzed by Mi d l a n d E a r t h S c i e n c e A s s o c i a t e s , Nottingham, U . K . APPENDIX 2A WHOLE ROCK ANALYSES: MAJOR ELEMENT OXIDES AND TRACE ELEMENTS (p.5) Var.MD: KA 221 KADDH3 6A KADDH3 6B KADDH4 9 SI02 AL203 TI02 FE203 MGO CAO NA20 K20 MNO P205 i n T 77.33 12 .69 0.10 0 . 66 0 .04 0.17 0.S3 7 . 79 0, 0 , 0 .! 00 01 76.92 12.36 0.16 1.19 0 . 02 0. 12 1 .73 6.23 0,00 0 . 00 0,63 76 , 7"' 13.25 0.16 1.13 0.00 0.11 1 .34 6 . 29 0 . 00 0.00 0.71 75.90 13 . 43 0 .35 1.11 0 . 03 0.13 2 .33 6 . 24 0 . 00 0 . 02 0.63 T o t s ! AG M w CL NB 100 . 20 1 14 7 -I o 10 13 100.29 . 0 0 . 1 3 0 43 12 0 13 0 S E SR T E U y Y Z R 0 64 0 6 6 24 37 4 0 10 0 3 3 56 "339 117 4 0 10 0 6 5 53 340 0 15 0 4 16 46 379 .Major element o x i d e s i n % Trace elements i n ppm Analysed by Mi d l a n d E a r t h S c i e n c e A s s o c i a t e s , Nottingham, U.K. APPENDIX 2B WHOLE ROCK ANALYSES: MAJOR ELEMENT OXIDES ( p . l ) LABHO" FIEL ji MUHBER Si02 Tr02 Ai203 FE203 FEQ HNO MGO CAQ N/»20 K20 P205 LOI TOTAL I I X I I I I I I I I I * R8611025 KCP-002 33.34 .57 12.97 9.67 R86U026 KCP-009 78.51 .11 12.46 .86 R8611027 KCP-012 74.93 .12 13.23 1.29 R861102B KCP-020 B 78.1 .11 12.08 .89 R8611029 KCP-027 71.71 .15 14.05 2.26 R8611030 KCP-028 68.72 .3 14.92 2.51 R8611031 KCP-035 76.26 .06 13.13 .48 R8611032 KCP-044 76.79 .29 13.67 1.28 R8611033 KCP-054 75.53 .14 13.09 2 R8611034 TCP-002 33.5 .57 12.84 9.74 R86U035 TCP-009 78.61 .11 12.36 .85 R8611036 SCP-005 65.12 .48 16.41 4.41 R86U037 BVL-190 65.01 .33 13.7 2.41 R86U03B KAD-042 74.35 .21 12.9 3.93 R8611039 GCP-013 72.06 .55 12.74 6.35 R8611040 GCP-018 50.19 .82 16.5 9.18 .33 4.81 18.57 1.25 2.43 .15 13.1 97.19 ,4R .05 .52 .02 4.39 .02 1.87 99.29 1.55 .29 .13 .02 4.05 .02 2.18 99.81 1.45 .13 .19 .09 5.44 .02 1.42 99.92 .54 .52 2.22 .16 6.03 .03 1.52 99.19 .74 1.08 2.78 .15 6.65 .08 1.34 99.27 .06 .02 .16 3.31 4.84 .02 1.34 99.68 .72 .3 .09 .14 4.36 .02 2.14 99.80 2.95 .16 .06 .02 3.9 .02 2.33 100.20 .33 4.81 18.43 1.17 2.49 .15 12.29 96.32 .45 .18 .52 .05 4.39 .02 1.85 99.39 .07 2.65 4.94 4.21 1.63 .13 .06 100.11 .06 .79 2.25 3.35 3.88 .08 7.85 99.71 .04 .29 .02 .02 4.21 .02 3.48 99.47 .02 2.33 .1 .72 2.17 .02 2.8 99.86 .15 5.5 6.33 .B7 1.82 .18 7.88 99.42 Major element o x i d e s i n % A n a l y z e d by Cominco L t d . L a b o r a t o r y , Vancouver,B.C. APPENDIX 2B WHOLE ROCK ANALYSES: TRACE ELEMENTS (p. 2) LAB NO FIELI mm l»(4) V UH) Hi Ri Si r U Co (2) Ni(2) As Si Pi Zn As SE u pm pm rm PPH PPH FPU PPH PPH PPH PPH PPH PPH PPH PPH PPH PPH PPH R8S11025 KCP-002 172 <a? (20 <20 79 229 <20 (20 (5 (4 R8411024 KCP-009 219 (20 (20 (20 12? 27 20 (20 124 35 R84U027 KCP-012 242 <20 22 (20 141 (20 (20 (2fl (5 (4 1.5 (4 94 14 204 (1 (.05 R8411028 KCP-020 1 272 (20 21 (20 158 27 (20 (20 (5 (4 R8411029 KCP-027 1481 (20 (20 (20 204 lot <20 (20 (5 (4 R841I030 KCP-028 U72 (20 21 (20 254 84 (20 (20 (5 (4 R841I031 KCP-035 41 (20 20 (20 258 (20 (20 <20 (5 (4 R841I032 KCP-044 313 21 (20 (20 185 (20 (20 (20 to (4 R86U033 KCP-054 133 (20 (20 23 248 (20 30 (20 (5 (4 7.9 5 414 24 144 (1 0.14 RB41I034 ICP-002 373 233 (20 (20 74 238 (20 (20 122 37 RB411035 KP-009 20? (20 (20 (20 135 21 (20 (20 (5 (4 RB61I03A SCP-0O5 499 80 (20 (20 (20 750 (70 (20 51 40 (.4 (4 (4 27 (2 1 (.OS RB4U037 0VL190 1124 52 (20 (20 157 380 (20 (20 13 5 R841103B MI-042 390 (20 (20 (20 197 (20 (20 (20 (5 (4 15.4 (4 102 29 12 (1 3.P0 R84U039 GCP-013 1414 47 (20 (20 44 85 44 (20 (5 (4 R8411040 GEP-018 491 245 (20 (20 40 98 27 (20 25 (4 Trace elements i n ppm A n a l y z e d by Cominco L t d . L a b o r a t o r y , Vancouver, APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP009 COR9 BROWN S i 3 4 . 6 4 7 34 . 365 34, .360 34 .341 34 .544 34 . 50 8 33 .748 33 .373 34 .608 34 . 231 T i 0 .224 0 .210 0 .235 0 . 263 0 .255 0 .257 0 .264 0 .253 0 .212 0 .130 A l 2 0 . 3 6 5 20 .137 13 .563 13 . 683 13 .834 13 . 866 13 .522 13 .743 20 .0 66 13 . 634 Fe 3 . 326 3 . 235 2 .613 2 . 578 2 . 322 3 .065 2 .643 3 .003 3 . 373 O £_ .320 Fe 0 .000 0 .111 1 .0 34 0 .813 0 .611 0 .562 1 .070 0 .735 0 . 237 0 . 836 Mn 32 .664 33 .056 33 .233 33 . 066 32 .865 33 .071 32 .343 32 .763 32 . 3 2 3 32 .610 Mq 0 .141 0 .123 0 .136 0 . 133 0 .167 0 .133 0 .166 0 .133 0 .156 0 . 133 Ca 5 . 2 1 2 5 . 343 4 .333 5 .181 cr V-1 .257 cr .235 5 .120 5 .330 cr OCT O • t_ 5 . 240 Na 0 .000 0 .022 0 .007 0 .0 26 0 .003 0 . 000 0 .000 0 .015 0 .000 0 .013 3 7 . 0 7 3 37 • 222 36 .130 36 .108 36 .465 36 . 756 35 .333 35 . 376 36 . 334 35 . 374 S i 5 . 343 5 .863 5 .862 5 . 855 5 .363 cr •_' .843 5 .811 5 .813 5 . 852 5 . b53 T i 0 .023 0 .027 0 .030 0 .034 0 .0 33 0 . 033 0 .034 0 .033 0 .027 0 .023 A l 4 .0 43 4 . 005 3 .335 o .356 3 .367 3 .363 3 .361 3 .382 q . 333 3 . 363 Fe 0 . 540 0 .464 0 .373 0 . 363 0 .415 0 .434 0 . 381 0 .430 o .477 0 .417 Fe 0.00 0 0 .014 0 .133 0 . 105 0 .0 73 0 .0 72 0 .133 0 .035 0 . 0 33 0 .115 Mn 4 . 666 4 • < 13 4 .810 4 ~r —' cr . i i O 4 .725 4 . 747 4 . 731 4 .747 4 . 717 4 . 716 Mq 0 .035 0 .0 32 0 .035 0 .0 35 0 .042 0 .034 0 .043 0 .036 0 .0 33 0 . 0 35 Ca 0 . 342 0 . 365 0 . 334 n . 346 0 . 356 0 . 361 0 .344 0 .377 0 .352 o . 353 Na 0.000 0 .007 0 .002 0 . 0 0 8 0 .003 0 .000 0 .000 0 .005 0 . 000 o . 0 0 4 1 6 . 1 0 3 16 .0 36 16 . 0 73 16 . 0 83 16 .032 I S .0 37 16 .104 16 .117 16 .101 16 .035 COMPOSITION FM 3 3 . 3 2 4 33 . 337 33 .354 33 . 330 33 .135 33 .366 33 .205 33 .331 33 --i cr cr . 1L. •_' •_' 33 .323 AL 3 . 752 7 . 744 o .113 -? . 613 7 .354 3 .124 3 . 1^  C; . 373 O •_> .234 8 .542 PY 0 .575 0 .513 o .555 0 .570 0 .634 0 .533 0 . 678 0 .567 0 . 633 0 .563 SP 7 5 . 6 7 5 76 .367 .250 76 . 30 6 76 .250 76 .213 76 .316 75 .773 75 . 333 75 .721 GR 1 4 . 5 3 4 14 . 633 10 .442 11 <—.—•"—) • O i •_' 12 . 743 12 . 322 10 .316 12 .531 13 .771 12 . 0 61 AD 0 .414 0 .731 . 3 . 633 3 .0 38 . 363 » .138 o .30 3 O .744 1 .30 3 .107 UU 0 .000 0 .000 0 . 0 0 0 0 .0 00 0 .000 0 .000 0 .000 0 .0 00 0 .00 0 0 .00 0 Major elements i n % Analy s e s by M. P i r a n i a n , Department o f G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP009 RIM5 BROWN Si 37 .161 37 .062 36 .143 36 .723 36 .613 37 .0 32 36 . 542 37 .032 36 .200 36 .557 T i 0 .032 0 .105 0 .062 0 .085 0 . 0 30 0 .077 0 .043 0 .070 0 .0 75 0 .185 Al 21 .266 21 .333 21 .203 21 .343 21 .211 21 .310 21 .260 21 .174 21 .104 21 . 0 34 Fe . 672 3 . 907 3 .313 3 . 880 3 . 342 3 .523 O . 746 o .725 q . 911 3 .753 Fe 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 Mn 32 . 383 32 . 738 33 .535 33 . 0 66 33 . 0 40 .751 •Zt cL . 707 32 . 732 33 .232 33 . 0 66 Mq 0 .144 0 .141 0 .133 0 . 153 0 .129 0 .161 0 .161 0 .171 0 .149 0 .136 Ca 4 . 334 5 .0 46 4 .777 .027 .167 5 .138 5 .019 cr .183 5 .0 32 cr .013 Na 0 .000 0 .015 0 .013 0 . 0 0 0 0 .011 0 .012 0 . 0 0 5 o .00 0 0 .003 n .016 10 0 . 317 100 .40 7 33 .365 10 0 . 233 100 . 10 0 100 . 0 70 39 . 435 100 .20 6 39 . 755 33 ,~i o Si £ . 0 0 0 5 . 380 cr ._\ . 30 3 5 . 348 5 .346 c . 330 cr .953 5 . 338 cr .914 5 .351 T i 0 .011 0 .013 0 . 003 0 .010 0 .010 0 . 0 0 3 0 . 0 0 5 o .003 o .00 3 0 .023 Al 4 .047 4 .063 4 .082 4 . 0 75 4 .053 4 . 0 62 4 .035 4 .0 35 4 .063 4 .0 47 Fe 0 .436 0 .527 0 . 535 0 . 525 0 cr o •-. 0 .477 0 . 511 0 . 50 4 0 .534 0 .512 Fe 0 .000 0 . 0 0 0 0 .00 0 0 .0 00 0 .000 0 . 0 0 0 0 .000 0 .000 0 . 0 0 0 0 .0 00 Mn 4 .512 4 .474 4 . 647 4 . 536 4 . 544 4 .487 4 .517 4 . 431 4 . 60 5 4 .553 Mg 0 .035 0 .034 0 . 0 33 0 .0 37 0 .0 31 0 .033 0 .0 39 0 .041 0 .036 0 .0 33 Ca 0 . 864 o 0 . 836 o .872 0 . 333 0 . 301 0 . 877 0 . 833 o .331 0 .374 Na 0 . 0 0 0 0 .005 0 .006 0 . 0 0 0 0 .003 0 .004 o .002 0 . 00 0 n .001 0 .005 15 .364 15 . 374 16 . 0 43 16 . 0 0 3 16 . 015 15 . 370 15 .993 15 .975 16 . 044 16 .004 COMPOSITION FM 99 .311 33 . 327 33 .358 33 .273 33 . 336 33 .225 93 .229 93 .183 99 .233 93 .354 AL y .404 8 . 336 .848 o .311 O . 708 . 0 33 . 599 O . 495 .330 3 . 530 PY 0 .583 0 .575 0 .554 o .617 0 * c- O o . 657 0 .658 0 .694 0 .601 0 . 553 SP 76 . 476 75 .835 76 .851 76 . 050 75 . 860 76 . 0 72 76 . 0 37 "7 cr 76 .107 76 . 436 GR 14 .361 14 .460 13 .634 14 .365 14 . 762 15 .0 35 14 .625 14 . 929 14 . 326 14 .0 83 AD 0 .170 0 .135 0 .113 0 .156 0 .147 0 . 142 0 .031 0 .129 0 .137 0 .342 IV 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .0 00 0 .000 Major elements i n % Analyses by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y of B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP009 CORE BROWN Si 36 .370 37 .131 36 .536 36 . 636 36 . 370 36 .532 36 .337 36 .384 36 .662 36 qoo T i 0 .233 0 . 237 0 .273 0 .153 0 .224 0 . 274 0 .250 0 .270 0 . 327 0 .270 Al 2 1 . 2 4 7 21 .0 56 21 .054 21 .077 21 .160 21 .058 20 . 363 20 .324 20 .843 20 .833 Fe 3 .630 .533 q .710 *i . 333 3 .752 q .357 .717 3 .683 O . 307 O •_* .631 Fe 0.000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 Mn 3 2 . 3 0 8 32 .523 32 .614 32 . 477 •~p •—1 O C_ .834 32 .836 32 . 615 33 .033 32 .828 .333 Mg 0 .121 0 .123 0 .123 0 .143 0 .156 0 .143 0 .143 0 .121 0 .131 0 .123 Ca 5.131 5 .331 5 .134 5 .233 5 .160 5 .128 c r .103 4 . 370 c r .118 5 .043 Na 0 .003 0 .000 0 .022 0 .005 0 .000 0 .003 0 . 012 0 .013 0 .000 0 .0 26 3 3 . 7 2 5 100 .110 33 .537 33 .718 100 .216 33 .335 33 .157 33 .465 33 .722 33 . 662 S i 5 .331 6 .003 5 .361 5 . 363 5 .363 c r ._j . 340 5 .350 c r .343 5 .371 c •_> .335 T i 0 .036 0 . 035 0 .034 0 . 013 0 .0 27 0 . 0 33 0 .031 0 .033 0 .040 0 .0 33 A l 4 .0 62 4 .012 4 .042 4 .042 4 . 0 37 4 .0 36 4 .047 4 .031 4 .002 4 . 023 Fe 0 . 433 0 .486 0 .505 0 . 535 0 .50 8 0 . 533 0 .503 0 .504 0 .513 0 . 436 Fe 0 .000 0 .000 0 .000 0 .000 0 .000 0 . 0 0 0 0 .000 0 .000 0 .000 0 .000 Mn 4 . 4 3 3 4 . 455 4 . 50 0 4 .476 4 . 510 4 .531 4 .524 4 .532 4 .523 4 .612 Mg 0 .023 0 .030 0 .031 0 .0 35 0 .0 38 0 .0 35 0 .0 36 0 .0 23 0 . 0 32 0 .031 Ca 0 .302 0 .334 0 . 306 0 .313 0 . 835 0 . 833 0 . 836 0 .371 0 . 333 0 q q q Na 0 .003 0 .000 0 .00 7 0 .002 0 . 000 0 .003 0 .004 0 .006 0 .000 0 .008 1 5 . 3 5 2 15 .354 15 .386 15 . 330 15 . 384 16 .008 15 .336 16 .004 15 . 336 l b .022 COMPOSITION FM 33 .411 33 .405 33 .334 33 .315 33 . 256 33 <—1 ^  ^  . O c L O 33 .233 33 .423 33 . 374 33 . 337 AL y . 536 3 . 253 3 .535 8 . 333 8 .558 3 . 00 4 S . 553 0 .452 3 . 717 O . 263 PY 0 .500 0 .503 0 . 523 0 . 531 0 .634 0 .573 0 . 606 0 . 434 0 .535 0 .525 SP 75 .310 75 .720 75 . 332 - 7 c r / . 260 76 .002 75 . 306 76 .074 76 .737 76 .137 76 .340 GR. 1 4 . 4 3 4 14 .385 14 .442 14 .367 14 .334 14 .103 14 .235 13 . 756 14 .00 6 13 . 875 AD 0 .561 0 .534 0 .513 0 .233 0 . 413 0 .50 4 0 . 466 0 .501 0 . 60 6 0 . 433 UV 0 .000 0 -.000 0 .000 0 .000 0 .00 0 0 .000 0 .000 0 .000 0 .000 0 .000 Major elements i n % Analy s e s by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , ^ The U n i v e r s i t y o f B r i t i s h Columbia. M APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP009 RIM6 BROWN Si 35.650 35 .307 35 .582 35 .631 35 .538 35 O^ cr 35 .625 35 .473 35 .313 35 . 207 T i 0 .073 0 .125 0 .087 0 . 0 73 0 .092 0 . 075 0 . 0 65 0 .120 0 . 085 0 .063 Al 20.392 21 .149 21 .015 20 .317 20 .747 20 .794 20 . 960 20 . 334 20 . 792 20 .363 Fe 3. 604 . 327 •—» O . 362 3 . 364 .563 3 . 398 . 421 3 . 273 3 . 474 . 633 Fe 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 .0 00 0 .000 0 . 0 0 0 0 . 0 0 0 0 .000 0 . 0 0 0 0 .000 Mn 33.923 33 . 552 33 .436 O Cr .171 33 .440 33 .846 . 60 3 . 460 33 . 666 .223 Mq 0 .106 0 .106 0 .033 0 .0 30 0 .113 0 .123 0 .033 0 . 0 33 0 .106 0 .035 Ca 4 .329 5 .0 73 5 .020 5 .162 5 .133 cr ._( . 0 20 cr .211 cr .123 5 .236 5 .141 Na 0 .022 0 .012 0 . 0 0 0 0 .0 20 0 . 0 0 4 0 .00 5 0 .013 0 .000 0 .0 00 0 .000 99.10 4 33 33 . 661 33 . 427 33 .632 93 . 536 98 . 396 93 .438 33 .172 98 . 343 Si 5.832 cr •_' .834 cr .883 5 . 833 cr .331 cr wi 1-.--. Ofc>-"' cr .877 . 880 5 . 399 cr vJ .851 T i 0 .010 0 .015 0 .011 0 . 0 0 3 0 .011 0 . 0 0 9 0 . 0 0 3 0 .015 0 .011 0.003 Al 4.063 4 .091 4 .035 4 .082 4 .047 4 .067 4 .075 4 .030 4 .0 36 4 .107 Fe 0 .497 0 .457 0 .465 0 . 466 0 .434 0 .472 0 .472 0 . 454 0 . 473 0 . 50 6 Fe 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 . 0 0 0 0 .000 0 .000 Mr. 4.741 4 . 665 4 . 631 4 . 652 4 . 683 4 . < -_>o 4 . 696 4 . 638 4 . 697 4 . 677 Mq 0 .026 0 .026 0 .025 0 .0 22 0 .023 0 .030 0 .0 23 0 .025 0 . 0 26 0 . 0 23 Ca 0 . 354 0 . 833 0 . 333 0 . 316 0 .311 0 . 393 0 .921 0 . 311 0 . 924 0 . 915 Na 0 .007 0 .00 4 0 .000 0 .006 0 .001 0 .002 0 .004 0 .000 0 .000 0 .000 16.073 16 .045 16 .053 16 .0 52 16 .0 73 16 . 0 94 16 .0 77 16 .063 16 .0 71 16 . 0 37 COMPOSITION FM 33.504 99 .436 93 .527 33 . 570 99 . 466 39 . " £— 99 . 560 93 . 525 99 .499 93 . 550 AL 8.135 7 .572 7 .666 t . 700 3 .0 73 7 . 672 { . 465 1 . 319 8 . 266 FY 0 .427 0 .430 0 .404 0 .365 0 .455 0 .494 0 .374 0 .404 0 . 426 0 . 333 SP 77.567 ~7 "7 ( < .341 / / . 363 76 . 831 76 . 673 i < . 403 76 . 397 77 .234 76 . 758 76 . 465 GP. 13.727 14 .426 14 .401 14 .30 8 14 .625 14 .294 14 . doo 14 .615 14 .342 14 . 769 AD 0 .143 0 .230 0 .160 0 .136 0 .163 0 .137 0 .119 0 • <C cl, Z~ 0 .155 0 .117 W 0 .000 0 .000 0 .000 0 .000 0 .000 0 . 000 0 .000 0 .000 0 .000 0 .000 Major elements i n % Analyses by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP009 RIM8 BROWN S i 35 .650 35 .928 35 .629 35 .456 35 .0 64 35 .704 34 . 966 35 .120 35 . 214 35 .543 T i 0 .122 0 .152 0 . 145 0 .155 0 . 178 0 .105 0 .133 0 .123 0 . 1 5 3 0 .172 Al 2 0 . 9 9 2 20 .838 21 .102 21 .455 cL ill .020 21 .351 21 .137 21 .412 21 . 206 20 ceo Fe 3 . 2 4 5 3 .421 3 .092 •n •-J . 353 .263 3 .483 3 . 296 o . 485 . 295 3 .323 Fe 0.000 0 .000 0 .000 0 .000 0 . 000 0 .0 00 0 .000 0 .000 0 .000 0 .000 Mn 3 4 . 5 5 4 34 . 299 34 . 662 34 . 395 . 674 33 . 633 34 .618 34 • d x o 34 . 499 34 .742 Mg 0 . 1 0 9 0 .091 0 .116 0 .103 0 .104 0 .136 0 .106 0 .10 8 0 .114 0 . 0 31 Ca 3 .877 .893 3 .804 <—> .694 q . 473 q .60 7 .694 .526 .554 . 333 Na 0 . 0 1 9 0 .018 0 .000 0 .030 o .0 30 0 . 027 0 .000 0 .000 n .013 0 .015 9 3 . 5 6 3 93 .690 98 .550 93 . 650 97 . 30 6 93 .046 98 . 0 0 0 '-17 . 992 93 . 0 49 93 . 376 S i 5 .90 4 5 .936 5 .S98 5 . 862 5 .824 5 .917 5 . 336 5 .348 cr .864 cr -J .314 T i 0 . 0 1 5 0 .019 0 .013 0 .019 0 .022 0 .013 0 .017 0 .015 0 .019 0 . 0 21 Al 4 . 0 9 7 4 .067 4 .117 4 .180 4 .311 4 .170 4 .168 4 .202 4 .162 4 . 0 30 Fe 0 .449 0 .473 0 .428 0 .464 0 .453 0 .483 0 . 460 0 .485 0 .459 n . 462 Fe 0.000 0 .000 0 .000 0 .000 0 . 0 0 0 0 .000 0 .000 0 .000 0 .0 00 0 .000 Mn 4 . 3 4 7 4 .30 0 4 .360 4 .816 4 . 733 4 . 721 4 . 894 4 . 826 4 . 866 4 .835 Mg 0 .027 0 .022 0 . 029 0 .027 0 .026 0 .034 0 . 026 0 .027 n .023 0 .023 Ca 0 .683 0 . 639 0 .675 0 .654 o . 618 0 .641 0 . 661 U . 629 0 .634 0 . 701 Na 0 .006 0 . 006 0 .000 0 .010 0 .010 0 . 0 0 9 0 .00 0 0 . 0 0 0 0 . 004 0 .005 16 .034 16 . 012 16 .024 16 .0 32 16 .001 15 . 937 16 . 062 16 .034 16 . 0 37 16 .0 51 COMPOSITION FM 9 9 . 4 9 3 99 . 576 99 .461 99 .50 0 99 . 50 4 99 . 359 99 . 50 9 99 .493 39 .470 99 .530 AL 7. 437 t .914 7 .156 / .80 3 / . 785 3 '-i -~. --i . 628 q .146 . 673 < .613 PY 0 .450 0 .376 0 .479 0 .446 0 .444 n .572 0 . 438 0 . 449 0 .475 0 . 373 SP 3 0 . 7 5 3 80 .363 81 .264 30 .949 31 . 334 30 .428 81 .143 81 .002 31 . 429 30 . 663 GR 1 1 . 0 3 3 11 .0 63 10 . 329 10 .511 10 .042 10 .577 10 . 536 10 .169 10 .129 11 .0 21 AD 0 .227 0 .284 0 .272 0 0 .345 0 .201 0 . 250 0 • t_* 0 .239 0 . 313 UM 0.000 0 .000 0 .000 0 .000 0 . 0 0 0 0 .00 0 0 .000 o .000 0 .000 0 .000 Major elements i n % Analyses by M. P i r a n i a n , Department o f G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. -J APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP012 RI14 BROWN Si 34 . 307 35 .013 35 .034 35 .002 34 .361 34 .765 34 . 80 3 34 .732 34 .632 34 . 340 Ti 0 .275 0 .20 7 0 .214 0 . c_ —1 1 0 .243 0 .225 0 .223 0 .224 0 . 214 0 . 259 Al 19 .413 19 . 537 19 .405 19 .057 13 .150 19 . 176 13 .152 19 . 244 19 .052 13. 055 Fe 6 .791 6 .516 6 .552 6 . 212 6 .017 6 . 348 6 . 401 cr . 30 8 6 . 20 7 5. 955 Fe 1 .241 1 .127 1 .322 1 .343 1 . 634 1 . 666 •i .702 1 .551 1 . 363 1 . 813 Mn i o .478 32 .927 .329 33 .158 . 360 O ~j ->_' C_ .337 --i o . 001 32 .731 .533 32. 725 Mg 0 .169 0 .162 n .153 0 .138 0 .172 0 .143 0 .124 0 .131 0 .144 0 . 144 Ca .313 2 . 768 2 .924 .975 2 .340 cL . 357 d . 367 .361 3. 070 Na 0 .013 0 .004 o .000 0 .031 0 . 0 o 0 0 .012 0 .005 0 .000 0 .000 0 . 000 93 .011 93 . 261 97 .937 98 .657 33 .134 98 .133 . 235 37 . 404 Q y . 725 37 . 366 Si 5 .873 5 .338 5 .90 3 5 . 331 cr .892 . 869 cr .863 cr ._i . 838 cr .377 5. 896 Ti 0 . 035 0 .026 0 .027 0 . 0 30 0 .0 31 o . 0 23 0 . 0 23 0 .0 28 o . 0 27 0 . 033 Al 3 .361 3 3 .854 3 .774 3 . 80 3 .816 3 . 80 7 3 .845 3 .303 3. 790 Fe 0 .958 0 . 916 0 . 923 0 .373 0 . 848 o . 336 0 . 30 3 0 . 833 0 .373 0 . 340 Fe 0 .158 0 .143 0 .163 0 .234 0 . 214 0 .212 0 .216 0 .133 0 .237 0 . 231 Mr. 4 . 642 4 . 690 4 .614 4 .719 4 . 70 5 4 . 710 4 . 714 4 .707 4 . 676 4 . 673 Mg 0 .043 0 .041 0 .0 40 0 .0 34 0 .043 0 .0 37 0 .0 31 0 .0 33 0 .0 36 0 . 0 36 Ca 0 .509 0 . 499 0 . 528 0 . 535 0 . 531 0 .517 0 .513 0 .504 0 . 537 0 . 555 Na 0 .004 0 .001 0 .000 0 .010 0 . 0 0 0 0 .00 4 0 .002 0 .000 0 .000 0 . 000 16 . 083 16 .077 16 .057 16 . 033 16 .067 16 . 083 16 . 0 89 16 . 050 16 .074 16. 0 59 COMPOSITION FM 99 . 267 99 .297 99 .311 99 .412 33 .254 93 .366 99 .467 33 .427 99 ~?cr • o«- O 33. 373 AL 17 . 742 16 .882 17 .436 17 . 350 16 . 793 17 . 434 17 . 578 16 .535 17 . 533 16. 348 PY 0 .676 0 . 649 0 . 632 0 .540 0 . 635 0 . 534 0 .491 0 . 529 0 .574 0 . 574 SP 73 .313 74 .769 73 .752 t O . 334 74 .424 74 .113 74 . 0 65 75 . 166 < o . 633 74 . 0 0 7 GR g .511 q .914 3 .771 .138 2 .531 q .464 C— .365 c_ . 620 2 .211 £- • 525 AD 4 .257 3 .735 4 .40 8 5 . 317 5 .516 5 . 400 5 . 501 5 .150 cr . 334 cr •_' . 945 UV 0 .000 0 .000 0 .000 n .000 0 .000 0 . 0 0 0 0 .000 0 .000 0 .000 0 . 0 00 Major elements i n % An a l y s e s by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. £ oo APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP012 RI18 BROWN S i 34 .555 34 . 446 34 .461 34 .534 34 .523 34 .546 34 . 559 34 .471 34 . 403 34 . 666 T i 0 .152 0 . 122 0 .155 0 .165 0 .187 0 . 202 0 . 143 0 .162 0 . 137 0 .143 A l 19 .511 19 . 297 19 .545 19 .396 19 .276 13 .354 19 . 227 19 . 353 19 . 169 13 . 333 Fe 4 .379 4 . 093 4 .530 4 . 467 4 . 272 4 . 533 4 . 321 4 . 325 4 . 152 4 .613 Fe 1 .209 1 .570 1 .160 1 .3S4 1 .542 1 .411 1 .662 1 .437 1 . 743 1 . 494 Mn 34 .760 35 . 119 35 .084 35 . 401 35 .151 35 .045 35 . 122 34 . 836 34 . 761 35 . 131 Mg 0 .116 0 .126 0 .144 0 .121 0 .123 0 .151 0 . 133 0 .123 0 . 116 0 . 113 Ca .472 2 . 617 2 . 646 C .594 •—r C_ . 633 .70 3 o . 661 . 695 . 716 2 . 902 Na 0 .011 0 .028 0 .000 0 .005 0 .012 0 .000 0 .000 0 .000 0 .000 0 .000 97 .165 97 . 422 97 . 725 98 . 066 97 .725 37 .346 97 . 829 97 .412 97 .20 2 33 .410 S i 5 . 376 5 . 356 5 .842 5 .342 c r . 354 5 .347 5 .357 5 • > j J 1 5 .861 5 .845 T i 0 .019 0 . 016 0 .020 0 .021 0 .024 0 .026 0 . 013 0 .021 0 . 013 0 .013 A l .910 . 867 3 .905 3 . 367 3 . '_> O 3 .360 .840 3 .877 .849 3 .343 Fe 0 . 623 0 . 583 0 .642 0 . 632 0 . 60 6 0 . 642 0 . 612 0 .615 0 . 591 0 .651 Fe 0 .155 0 .201 0 .148 0 .176 0 .197 0 .130 o . 212 o .134 0 .224 0 .190 Mn 5 .0 06 5 . 057 5 .037 5 . 073 5 . 049 5 . 0 24 5 .041 c r .014 c r . 016 c r .017 Mg 0 .029 0 .032 0 .036 0 .031 0 .032 0 .038 0 .034 o .032 0 . 023 0 .028 Ca 0 .450 0 .477 0 .481 0 .470 0 . 478 0 . 430 0 . 433 0 . 491 0 . 436 0 . 524 Na 0 .004 0 .009 0 .000 0 .002 o .004 0 .000 0 .000 0 .000 0 . 0 0 0 0 .000 16 .073 16 .0 97 16 • 111 16 .114 16 .097 16 .106 16 .097 16 .090 16 . 0 34 16 .113 COMPOSITION FM 99 .494 99 . 456 99 .378 99 . 484 39 .452 33 --I c r ~i • OJO 99 432 99 .447 99 .437 33 .513 AL 12 .434 12 . 357 12 . 476 12 . 689 12 . 643 12 . 317 12 '-5 38 12 .627 12 O c r -~1 13 .137 PY 0 . 471 0 . 50 4 0 . 576 0 .479 0 .50 3 0 . 539 0 . 526 0 .511 0 .464 0 .443 SP 80 .077 79 . 769 79 .547 79 . 647 79 .537 73 .017 79 . 125 79 , 2 ~^  y 79 . 0 33 73 . 40 4 GP, 3 .027 2 . 397 . 616 . 733 2 .325 . 364 —i d .164 cl . 909 c_ .0 33 3 .30 9 AD O .991 4 . 973 3 . 735 4 . 446 4 . 387 4 . 60 3 c r . 243 4 . 655 c r . 546 4 . 707 W 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 o .000 0 . 0 0 0 0 .000 0 .000 Major elements i n % An a l y s e s by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP012 RI23 BROWN Si 33 .952 33 .388 34 .155 33 .377 33 . '377 34 .50 6 34 .737 34 .018 34 .506 34 .153 T i 0 .123 0 .105 0 .105 0 .0 73 0 .163 0 .170 0 .175 0 .155 0 .102 0 .152 Al 13 .137 13 .377 13 .341 13 cr —i cr 18 . 407 13 . 10 9 13 .141 18 . 536 18 .553 13 .319 Fe 4 .224 4 . 246 4 .0 70 4 .563 O . 979 4 . 520 4 . 553 4 . 715 4 . 769 4 .326 Fe •n .313 £ l .381 vJ .040 2 . 631 2 . 867 . 337 3 . 233 2 . 633 2 .734 3 .022 Mn 34 .073 34 .234 34 .178 33 . 723 34 . 400 34 . 0 53 33 . 838 34 . 056 34 .042 33 . 691 Mq 0 .093 0 .033 0 .030 0 . 0 33 0 .114 0 . 085 0 .114 0 .114 0 .124 0 .099 Ca 2 .747 2 .973 3 .173 cL . 333 •—i . 891 c l . 713 d . 322 •o . 350 2 . 734 q .131 Na 0 .003 0 .000 0 .001 0 .012 0 .008 0 .005 0 .000 0 .004 0 .019 0 .001 36 .675 97 .063 37 .154 36 .624 96 .312 97 .497 37 .304 97 .142 37 . 633 36 . 394 Si £7 .346 5 .830 5 .346 5 .841 5 .836 cr i cr a '_J -_' cr .30 2 cr wi O ~ "7 . '-J C_ l cr .870 .355 T i 0 .016 0 .014 0 .014 0 .010 0 .0 22 0 .0 22 o . 022 0 .020 0 .013 0 .020 Al 3 .681 3 .715 3 . 700 . 765 o . 726 q . 640 q . 627 q . 742 q . 720 3 .701 Fe 0 .608 0 . 603 0 . 583 0 . 656 0 . 572 0 .645 o . 647 0 . 675 0 .679 0 .620 Fe 0 .429 0 .385 0 . 332 o .347 0 .371 0 . 423 0 . 421 0 .347 0 .350 0 .390 Mn 4 .970 4 .382 4 . 955 4 .311 cr . 0 0 4 4 .919 4 . 370 4 .341 4 . 306 4 .392 Mg 0 .024 0 .024 0 .023 0 .0 25 0 .029 0 .021 0 .0 23 0 .0 23 0 .0 32 0 .0 25 Ca n .507 0 . 547 0 . 582 0 . 534 o . 532 0 . 496 0 . 531 0 .523 0 . 50 3 0 cr —r cr . •-> .• Na 0 .003 0 .000 0 .000 0 .004 0 .00 3 0 . 0 0 2 o . 0 n n 0 . 0 01 n . 0 0 6 0 .000 16 .083 16 .105 16 . 093 16 .033 16 .094 16 . 0 53 1 6 . 0 50 16 . 10 7 16 .0 33 16 .0 79 COMPOSITION FN 99 .605 33 .604 33 . 616 33 . 571 99 . 510 99 . 643 33 .515 33 .513 33 .471 33 .571 AL 15 .508 15 .0 32 14 . 863 15 . 502 14 . 330 16 .072 16 .133 15 . 654 15 . 313 15 . 463 PY 0 .356 0 . 360 0 . 343 0 .334 0 . 447 0 • -J £— <C 0 .437 0 . 447 0 .435 0 .389 SP 74 . 296 75 .614 75 . 631 75 . 320 76 . 390 -? o . 633 —' O i C* cr i—(-—i • O '> o —• cr . 651 —«cr . 444 74 . 920 GR 0 .000 0 .000 0 . 0 0 0 0 .000 0 . 0 0 0 0 . 0 0 0 o . 0 0 0 o . 0 0 0 o . 0 0 0 0 .000 AD 9 . 833 8 . 344 q .150 3 .133 .783 9 .317 3 . 347 . 247 O . 254 3 <"-» i m £LZ -Z> U'v' 0 . 0 0 0 0 .0 00 0 .000 0 . 0 0 0 0 . 0 0 0 0 .000 0 . 0 0 0 o . 0 0 0 0 .000 0 . 0 0 0 Major elements i n % Analy s e s by M. P i r a n i a n , Department o f G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP012 RI24 BROWN Si 33 .731 34 .634 34 . 739 34 .544 34 .846 34 . 762 34 34 . 715 34 . 316 34 . 820 T i 0 .175 0 .205 0 . 137 0 . 157 0 .205 0 . 135 0 .140 0 . 175 0 .162 0 . 130 Al 17 .446 17 . 533 17 .145 17 .504 17 .493 17 . 667 17 .410 17 .725 17 .938 1 3 . 364 Fe .214 3 . 857 o . 715 3 . 531 . 753 ••-» . 338 q . 717 O . 645 4 . 127 4 . 246 Fe 4 .293 4 .196 4 .SI 6 4 .280 4 .276 4 . 013 4 . 473 o . 950 O . 566 2 . 365 Mn 34 . 619 34 .294 34 . 426 34 . 552 34 .543 34 . 446 34 .494 34 «-i •-, •-, • '_• C_ 34 . 446 3 4 . 553 Mq 0 .071 0 . 083 0 . 096 0 . 0 99 0 . 109 0 . 103 0 . 0 99 0 .108 0 .114 0 . 103 Ca 3 .074 .140 .120 3 .10 2 .127 .0 25 q .322 .217 .257 O • 017 Na 0 .000 0 .000 0 . 016 0 .000 0 .011 0 . 023 o .000 0 .000 0 .000 0 . 018 36 . 630 97 . 942 98 . 260 97 . 770 98 . 373 38 .0 75 33 .50 7 93 . 363 93 . 477 3 3 . 27y Si 5 .331 5 .392 5 . 901 5 . 883 c r wi .302 c r . 300 5 . 399 5 . 332 cr .334 5 . 836 T i 0 .0 23 0 .026 0 .0 24 0 . 020 0 . 026 o .0 24 0 . 013 0 .022 o .0 21 0 . 0 23 Al 3 .554 o .515 o . 433 O . 516 3 .432 3 c r - ~ i si • Ju4 3 .473 3 . 539 . 583 3 . 653 Fe 0 .465 0 . 549 o .523 0 .50 3 0 c r ^  ' - i 0 .545 0 . 526 0 .516 0 . 583 0 . 60 0 Fe 0 .559 0 . 537 0 .616 o .549 0 . 545 0 .513 0 .570 0 .50 4 0 .454 0 . Tji ~7 ~7 \-' < f Mn c r . 069 4 . 942 4 . 953 4 . 939 4 . 357 4 .352 4 . 346 4 . 993 4 . 931 4 . 348 M Q o .013 0 .021 0 .024 0 .0 25 0 .0 23 0 . 0 28 0 .0 25 0 .027 0 . 0 23 0 . 0 23 Ca 0 . 569 0 .572 0 . 568 0 .567 0 .563 0 . 550 0 . 60 2 0 . 584 0 .530 0 . 546 Na 0 .000 0 . 0 0 0 0 . 005 0 .00 0 0 . 0 0 4 0 . 0 0 8 0 . 0 0 0 0 . 0 0 0 0 .000 0 . 006 IS .033 16 .054 16 .052 16 .0 57 16 . 0 53 16 . 054 16 .0 53 16 . 0 73 16 . 0 75 1 6 . 0 74 COMPOSITION FM 3 3 .699 99 . 652 99 .60 2 99 . 583 99 .544 33 .541 99 .536 99 . 550 93 .513 33 . cr -? •_' •Z> i AL 14 • t' o o 15 -9 l - i r—J • i •_• _ 16 .181 15 .234 15 . 60 6 15 . 433 15 .736 14 . 954 15 . 435 1 4 . 346 PY 0 .264 0 .306 0 .345 0 .366 0 . 400 0 .40 5 0 . 362 0 . 399 0 .430 0 . 422 SP "7 P .720 71 .847 70 .101 . 213 71 .310 .516 71 232 s 3 . 279 7-J . 647 7 5 . 667 GR 0 .0 00 0 .000 0 . 0 0 0 o .000 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 .0 00 0 . 0 00 AD 12 .323 12 . 059 13 . 373 12 .182 12 .133 11 cr »-icr • %J O 12 . 550 11 .369 10 . 433 o 366 0 .000 0 .000 0 .000 0 .000 0 . 000 0 . 0 0 0 0 .000 0 .000 0 .0 00 0 . 0 0 0 Major elements i n % An a l y s e s by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP054 R208 BROWN Si 35 .111 34 .921 34 .329 Ti 0 .123 0 . 307 0 . 350 Al 13 .347 13 .673 19 . 790 Fe 4 . 273 4 .0 27 q . 974 Fe 0 .571 0 .814 0 <=;oo Mn 37 .144 O / . 282 .353 Mq 0 .030 0 .0 91 0 .106 Ca 1 .220 1 . 237 1 . 223 Na o .000 0 .020 0 .005 33 .485 38 . 372 93 .224 3 4 . 6 0 4 3 4 . 8 0 1 3 4 . 6 3 4 0 . 3 9 7 0 . 4 2 4 0 . 4 1 0 2 0 . 1 4 0 1 3 i~, --. 1 9 . 5 3 5 4 . 5 3 9 4 . 1 1 3 . 3 4 6 0 . 0 0 0 0 . 4 6 5 0 . 9 2 0 "7 . 7 0 9 3 7 . 0 6 5 o < . 1 3 9 o . 0 8 1 0 . 1 0 6 o . 0 7 0 I 2 -** 1 m cZ.cZ. / 1 . 2 5 6 o . 0 0 0 0 . 0 0 8 o . 0 0 0 9 3 . 6 9 2 3 8 . 0 3 6 9 7 . 3 1 1 3 4 . 7 0 9 3 4 . 3 1 6 3 4 . 6 9 0 3 4 . 2 1 7 0 . 4 3 5 0 . 3 3 5 0 . 4 3 9 0 . 5 0 9 1 9 . 6 9 2 1 3 . 3 0 6 1 9 . 9 1 1 1 9 . 7 7 7 4 . 0 '33 q . 3 1 3 4 . 3 6 2 . 7 5 3 0 . 6 5 7 o . 5 2 0 0 . 3 1 3 0 . 4 4 7 '-[ ~7 . 4 5 5 . 4 1 1 3 "7 . 3 0 6 3 7 . 1 5 1 o . 1 0 8 0 . 0 8 1 0 . 0 6 3 0 . 0 7 1 I . 2 9 3 1 . 2 2 4 1 . 2 6 9 1 . 2 3 3 0 . 0 0 4 o . 0 0 9 0 . 0 1 9 0 . 0 0 5 9 8 . 4 5 3 3 8 . 1 3 2 9 3 . 3 7 3 9 7 . 1 7 5 Si e r . _ i .301 5 .884 5 .875 5 5 .876 c r .370 5 . 352 5 . 874 c r . 349 5 . 835 Ti 0 .016 0 . 0 39 0 .0 44 0 .0 50 0 . 0 54 o .0 52 0 . 0 55 0 . 0 50 0 .0 56 0 . 0 65 Al q .351 .907 . 3 . 934 3 . 995 •Z$ .945 3 . 90 3 .913 . 938 3 .957 3 .375 Fe 0 .601 0 . 567 0 . 561 0 . 639 0 . 581 0 . 545 0 . 578 0 c r c r -z> 0 .615 n .536 Fe 0 .0 72 0 .103 0 .075 0 .000 o .0 59 0 .117 0 .083 0 . 066 o .040 0 . 0 57 Mn 5 5 . 321 5 . 337 5 . 376 5 . 301 5 . 332 c r . 349 5 .347 c r .328 c r w i . 367 Mq 0 .022 0 .023 0 .027 0 .020 0 .027 0 .013 0 .027 0 .0 20 0 .017 o .013 Ca 0 .220 0 .223 0 .221 0 . 220 o 0 . 228 o . 234 0 .221 0 . 229 o . 226 Na 0 .000 0 .007 0 .002 0 .000 o . 0 0 3 0 . 0 0 0 0 . 0 01 0 . 0 0 3 o .006 o . 0 0 2 16 .0 70 16 .074 16 . 0 76 16 .126 16 .063 16 . 0 66 16 . 0 93 16 .0 73 16 .093 16 . 0 32 COMPOSITION FN 33 . 625 39 .619 99 . 555 99 . 662 39 .553 99 . 707 99 .551 99 . 659 99 .715 39 . 637 AL 10 .375 10 . 791 10 .255 10 .262 10 .402 10 . 626 10 . 60 3 10 .0 21 10 . 570 . 625 PY 0 .362 0 .369 0 .431 0 .327 0 .434 0 . 282 0 .434 0 . 331 0 . 276 0 .234 SP 35 .367 35 .623 86 .176 36 . 356 86 .083 C , c r . .515 85 . 750 86 .552 35 . 993 o / . 0 46 GR 1 .413 0 .164 0 .684 c_ . 328 0 . 356 0 .000 0 .411 0 . 762 1 .331 o . 637 AD 1 .377 3 .054 2 .454 0 . 726 .225 3 rr ~? —? .30 2 . 334 1 . 771 cZ, . 343 UV 0 .000 0 .000 0 .000 0 .000 o .000 0 .000 0 .000 0 .000 0 .000 0 .000 Major elements i n % > Analy s e s by M. P i r a n i a n , Department of G e o l o g i c a l Sciences, The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP054 R210 BROWN S i 34 . 673 34 .546 34 .698 34 . 399 35 .120 35 .113 .113 35 .017 34 . 693 34 . 683 T i 0 .252 0 .244 0 .132 0 .209 0 .150 0 .133 0 .138 0 .033 0 . 0 77 0 . 0 80 Al IS .400 13 .394 18 .394 18 .322 18 .303 13 . 236 18 .169 13 .535 13 .633 13 .541 Fe d" . 643 r> c_ .738 c- . 583 2 .631 . 339 . 623 <~> .395 q . 345 2 . 877 2 . 731 Fe •—, c l .323 2 .327 2 .896 2 .934 3 .0 73 3 .114 3 . c ;oo 2 .703 2 . 566 o . / f C-Mn 33 .532 37 .977 33 .312 33 .272 38 . 266 38 .543 .929 33 .444 33 . 445 3 P. .357 Mq 0 .090 0 .126 0 .096 0 .104 0 .113 0 .033 0 .113 0 .124 0 .123 0 .103 Ca 0 .802 0 .844 0 . 877 0 .739 0 . 845 0 .344 0 .923 0 r- i 0 .858 n . 302 Na o .000 0 .000 0 .003 0 .00 9 0 .004 0 .012 o .000 0 .015 0 .0 32 0 .000 98 .263 97 .745 98 .047 98 .220 98 . 273 93 . 834 33 . 0 64 38 . 70 6 38 .353 33 .135 S i c r vJ .333 5 .890 c r . 899 5 . 919 5 .944 5 . 322 .953 5 .311 5 .333 cr \J . 833 T i n .0 32 0 .031 0 .023 0 .027 0 .019 0 .018 o .013 0 .012 0 .010 0 .010 Al 3 .632 3 .696 3 . 686 3 . 662 .651 o -.j . 636 q .631 3 .637 3 .733 3 .713 Fe o .376 0 .398 0 .367 0 • / •—' o . 340 0 .371 0 . 340 0 .402 0 .408 0 . 397 Fe 0 .361 0 .363 0 .370 0 .381 0 .391 0 .335 0 .419 0 .344 0 .327 0 .354 Mn 5 .549 5 .484 5 .517 5 .498 5 . 436 5 . 50 5 cr . 447 cr w i . 437 5 .521 cr . 520 Mq 0 .023 0 .032 0 .024 0 .026 0 .0 23 0 .025 0 . 028 0 .031 0 .031 0 .027 Ca 0 .146 0 .154 0 .160 0 .143 0 .153 0 .171 o .163 0 .158 0 .156 0 .146 Na 0 .000 0 .000 0 .003 0 .003 0 . 001 0 .004 0 . 0 0 0 0 .005 0 .011 o .000 16 .057 16 .048 16 .049 16 .0 33 16 .014 16 .0 46 16 . 0 0 3 16 .057 16 .080 16 . 0 61 COMPOSITION FM 99 .641 99 .490 99 .612 99 .579 99 .545 33 . 60 3 qg . 543 33 . 501 33 .507 33 .567 AL 10 . 709 11 .100 10 . 760 10 .969 10 . 672 11 .0 31 11 . 0 27 10 .365 10 .334 10 . 930 PY 0 .329 0 .468 0 .355 0 .384 0 .415 0 .362 0 .414 0 . 460 0 .457 0 .333 SP 80 . 675 80 .0 80 30 .474 79 . 933 80 . 0 91 73 . 734 73 .192 80 .827 81 . 345 30 . 713 GR 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 AD 8 . 286 8 .353 8 .410 8 . 653 8 r~, i • '—• c_ c L O .313 9 .366 7 .747 7 .364 . 90S U'v' 0 .000 0 .000 0 .000 0 .000 0 .000 0 .0 00 0 .000 0 .000 0 .000 0 .000 M a j o r e l e m e n t s i n % A n a l y s e s by M . P i r a n i a n , Depar tment o f G e o l o g i c a l S c i e n c e 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 . APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP054 R211 BROWN Si 35 .438 35 .242 35 . 263 35 .093 35 .033 34 .342 34 .542 34 .873 34 -70 c r 34 .916 Ti 0 .173 0 .130 0 .178 0 .152 0 .132 0 .145 0 .200 0 .264 0 .325 0 . 314 Al 20 .102 20 .263 20 .113 19 .391 19 .336 13 . 601 13 .434 13 . 473 13 . 369 19 . 375 Fe 4 . 638 4 .827 4 .730 4 . 0 26 3 . 346 4 . 0 34 d< . 742 . 80S . t C- { 3 . 740 Fe 0 .276 0 .015 0 .250 0 .630 0 . 735 1 . 0 36 1 .133 1 .148 1 . 262 1 .262 Mr. 37 . 420 37 .275 37 . 658 37 .693 37 .514 37 . 645 ~7 •D 1 . 558 37 .0 57 . 835 0 * 7 W ( .339 Mq 0 .139 0 .144 0 .123 0 .129 0 .156 0 .133 0 .164 0 .033 0 .133 0 .109 Ca 0 .621 0 . 666 0 . 670 0 . 701 0 . 323 0 .80 5 0 .816 0 . 731 0 . 770 0 . 819 Na 0 .003 0 .004 0 .000 0 . 000 0 .012 0 .007 0 .008 0 .011 0 .000 0 .000 93 .S72 93 .622 33 .064 98 . 320 98 .241 38 .461 37 . 713 37 .523 98 .155 37 .374 Si c r .927 c r •_l . 903 5 .900 5 . 90 9 c r . 310 c r .330 c r . 363 c r .317 c r •_l . 373 5 . 910 Ti o .022 0 .023 0 .022 0 .019 0 .017 0 . 013 0 . 0 26 0 .0 34 0 .0 41 0 .040 Al 3 . 962 4 .005 3 . 966 3 .947 q .338 c' . 334 . 30 3 3 .335 3 . 363 3 .865 Fe 0 . 656 0 . 677 0 . 670 0 . 567 0 . 556 0 c r —? -7 0 c r -—1 0 . 540 0 . 527 0 . 529 Fe 0 .035 0 .002 0 .031 0 . 0 30 0 .0 33 0 . 138 0 .152 0 .147 0 .161 0 .161 Mr. c r ._i . 301 5 .293 c r •_i ^ -1 c r . j j j 5 - i - ? c r • -Z't •_' . 352 c r . 375 c r _i . 40 5 c r . 325 c r • J . 423 5 . 353 Mg 0 . 0 35 0 .0 36 0 .032 0 . 0 32 0 . 0 33 0 .0 35 0 .042 0 .0 25 0 . 0 33 0 .023 Ca 0 .111 0 .120 0 .120 0 .126 0 .143 0 .145 0 .143 0 .142 0 .140 0 .148 Na 0 .003 0 .001 0 .000 0 .000 0 . 00 4 0 .002 0 . 0 0 3 0 .00 4 0 .000 0 .000 16 .052 16 .065 16 .077 16 .0 56 16 . 053 16 .0 75 16 . 0 73 16 . 0 28 16 . 0 67 16 .035 COMPOSITION FM 99 .424 99 .40 0 33 .469 99 . 464 33 33 .435 33 • cl c_ 33 . 530 99 .455 33 .545 AL 11 . 274 11 . 0 99 11 . 359 10 . 445 10 . 476 11 . 261 10 . 714 10 . 325 10 . 715 10 . 372 PY 0 . 567 0 . 530 0 .522 0 .524 0 .632 0 .545 0 .651 0 qqq 0 .521 0 .435 SP 36 . 561 86 c r -7 —t . •_ ' < O 86 . 392 86 .813 86 . 336 34 . 630 34 . 701 34 . 70 3 34 . 430 34 . 327 GR 0 .416 1 .354 0 . 635 0 .000 0 .000 0 .000 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 .000 AD 1 .132 0 . 330 1 .092 .213 . 437 .515 q . 334 . 378 4 .334 4 . 365 UV 0 . 0 0 0 0 .000 0 .000 0 . 0 0 0 0 . 0 0 0 0 .0 00 0 . 0 0 0 0 . 00 0 0 .0 00 0 . 0 0 0 Major elements i n % Analyses by M. Piranian, Department of Geological Sciences, The University of B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP009 R216 PINK S i 35 .254 35 .272 35 .331 35 .620 35 .494 35 . 569 35 .762 35 O ^ c r 35 . 755 35 .173 T i 0 .103 0 .123 0 . 103 0 . 097 0 . 0 63 0 .110 0 . 113 0 .113 0 .120 P . 122 A l 20 . 334 20 . 276 20 . 268 20 . 333 20 . 565 20 .575 20 . 603 20 . 546 20 . 525 20 .423 Fe 13 .599 13 .615 13 . 453 13 . 450 13 . 275 13 .151 12 . 404 12 . 754 12 . 253 11 . 380 Fe 0 .000 0 .059 0 . 086 0 .000 0 . 0 0 0 0 .000 0 .000 0 .000 0 .000 0 .000 Mn 25 .344 25 .326 25 . 366 25 .511 25 . 506 26 .163 25 .724 26 . 324 26 . 216 26 .517 Mq 0 .401 0 .405 0 .400 0 .398 0 . 443 0 .375 0 . 370 0 .400 0 .370 0 .330 Ca .084 2 .934 . 053 2 . 996 . 917 2 .912 ~ i .130 q .134 q .0 63 O .20 0 Na 0 .001 0 .000 0 . 013 0 .011 0 .000 0 .005 0 .000 0 .000 0 .0 03 0 .0 05 93 .172 98 .011 33 .140 33 . 470 98 . 263 93 .860 38 .171 33 . 50 7 33 . 311 37 . 70 0 S i 5 .393 5 .910 5 . 313 . 932 5 .918 5 .906 c r .343 5 0 7 7 . i" { 5 . 343 5 .301 T i 0 . 013 0 .016 0 .014 0 .012 0 . 00 3 0 .014 0 . 014 0 .014 0 . 015 0 .015 A l 4 .019 4 .004 3 . 335 4 . 0 0 2 4 .041 4 .0 27 4 .0 41 4 .039 4 .024 4 . 0 33 Fe 1 . 903 1 . 908 1 . 332 1 .873 1 . 351 1 .326 1 . 726 1 . 773 1 .70 4 1 .667 Fe 0 .000 0 . 007 0 .011 0 .000 0 .00 0 0 .000 0 . 0 0 0 0 . 0 0 0 0 .000 0 .000 Mn .591 .594 o . 593 q 5v19 •~' . 6 0 2 . 630 q .625 q . 713 . 634 *-• . 768 Mq 0 . 100 o .101 o .100 0 .099 0 .110 0 .093 0 . 0 32 o . 033 0 .032 0 . 0 35 Ca o .553 0 c r » - 7 . • - ' , o . 547 o . 535 0 .521 0 . 513 0 . 563 o . 560 o . 547 0 . 575 Na 0 .00 0 o .000 0 .004 0 . 0 0 3 0 . 0 0 0 o . 0 0 2 0 . 0 0 0 0 .000 o .001 0 .002 16 .078 16 . 0 6 7 16 . 0 65 16 . 0 55 16 .051 16 . 0 65 16 .014 16 . 0 87 16 . 024 16 .063 COMPOSITION FM 93 .211 38 . 199 38 . 217 33 98 . 0 22 98 .343 38 n i c . 1 U 98 . 225 38 . 330 33 . 233 AL 30 .991 31 . 253 30 . 30 0 30 . 713 30 . 446 29 . 336 . 750 28 .331 •—. (-, d, O ~7 ~~» . 343 PY 1 . 630 1 . 643 1 . 627 1 .620 1 .310 1 .513 i 1 . 616 1 .521 1 . 553 SP c r i -. _ i >~< . 502 53 . 654 53 . 674 53 .015 59 . 250 60 .240 60 . 331 60 .433 61 . 273 61 .315 GR 8 . 686 C 1 .032 q .333 8 . 463 o . 376 o .143 3 . 113 q . 762 o . 633 g .0 53 AD 0 .191 0 . 412 o . 466 0 .179 0 . 113 0 . 2 0 3 0 . 213 0 . 20 3 0 . 224 0 T 0 7 UV 0 .000 0 . 000 0 .000 0 . 0 0 0 0 .000 0 .000 0 . 0 0 0 0 .000 0 .0 00 o .000 Major elements i n % Analyses by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP009 R218 PINK Si 34 .313 34 . 670 34 .996 35 .175 34 .346 34 .240 34 . 364 34 .805 34 .506 34 .664 T i 0 .203 0 .214 0 .123 0 . 135 0 .137 0 .254 0 .137 0 .20 3 0 .225 0 .130 A l 20 .257 20 .047 13 .873 13 .357 19 .738 19 .319 19 . 364 13 . 764 13 .362 13 . 730 Fe 10 . 0 S3 o .323 t~t '.J . 240 / .631 6 .190 c r ' - i . — i e~. c r . 0 54 4 . 466 4 .552 4 . 0 06 Fe 0 . ij 0 4 0 .323 0 .671 0 .482 0 . 726 0 ( T q q 0 . 467 0 . 763 0 .442 0 . 334 Mn 23 . 4S0 23 .227 29 .50 5 30 .351 31 .181 31 . 60 7 31 . 523 31 . 617 O d . 336 32 .356 Mq 0 . 2S0 0 .262 0 .237 0 .245 0 .20 4 0 .172 0 .131 0 .177 0 .163 0 .146 Ca o .147 3 .178 3 .175 2 . 338 3 . 786 q . 995 4 . 200 4 c\ 2. 4 .248 4 . 430 Na o .000 0 .012 0 .000 0 .00 0 0 .000 0 . 0 0 0 0 . 0 0 5 0 .007 0 .013 0 .003 37 .323 36 .755 96 .326 37 .0 34 37 .023 96 . 0 46 36 . 555 36 . 321 36 .508 36 .424 Si c r ,_i .331 5 .834 c r .326 c r . 333 5 . 908 5 .354 5 . 313 5 . 303 5 .365 5 .330 T i 0 . 0 2S 0 .027 0 .016 o .025 0 .0 25 0 . 0 3 3 0 . 0 25 0 . 0 27 0 .0 23 0 .024 A l 4 .028 4 .010 .363 o . 371 3 .945 q .993 3 . 334 .355 O .339 0 .351 Fe 1 .420 1 1 .167 1 .077 0 . 875 0 .762 0 .716 0 . 634 0 .647 0 . 563 Fe 0 .001 0 .041 0 .035 0 . 0 61 0 .092 0 . 0 81 0 . 0 60 0 . 0 37 0 .057 0 .107 Mn 4 . 0 S 7 4 . 201 4 • — •—1 C— 4 .340 4 .465 4 . 71 4 . 521 4 .547 4 . 662 4 . 657 Mq 0 .0S5 0 . 066 0 a 0 60 0 .0 62 0 . 0 51 0 . 0 44 0 .0 46 0 .045 0 .043 0 .0 37 Ca 0 . 5S3 0 c r ~? <~t . •_' t o 0 . 576 0 .542 0 . 686 0 • i O £ _ 0 . 762 0 . 321 0 . 774 .0 . 817 Na 0 .000 0 .004 0 .0 00 0 .000 0 . 0 0 0 0 .000 0 . 0 0 2 0 . 0 0 2 0 . 0 0 6 0 .0 03 IS .0S7 16 .064 16 . 0 30 16 . 018 16 . 0 47 16 . 0 75 16 . 0 33 16 . 0 37 16 . 0 30 16 . 0 56 COMPOSITION FM 33 .321 33 .308 93 . 321 38 .835 33 .0 63 99 .196 33 .146 33 .157 33 .203 33 .312 AL cr. o . 2S3 21 .124 20 .435 13 . 763 15 . 719 13 . 649 12 . 731 11 . 338 11 .411 10 . 350 PY i .0 72 1 .082 0 . 373 1 .013 0 «—i c r • C ' -Z> 0 .711 0 . 743 0 • f' C * •"' 0 . 635 0 . 533 SP ss . SO 3 63 . 623 69 . 254 71 .526 . 546 74 . 10 3 74 cr -1 74 .135 75 . 626 75 . 444 GR. q . 653 / . 761 6 . 343 6 .814 q . 234 q . 0 33 10 . 431 10 •-t c r -? . -_' •_' e 10 .472 10 . 0 63 AD 0 .403 1 . 410 . 323 1 . 880 2 . 616 . 448 1 O -~< C ' j i 1 . 796 c . 344 UM 0 .000 0 .000 0 .000 0 . 0 0 0 0 . 0 0 0 o . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 000 Major elements i n % Analyses by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , u The U n i v e r s i t y o f B r i t i s h Columbia. ^ APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP009 R220 PINK Si 35.063 35 .177 35 .488 35 .610 35 .713 35 .223 35 . 773 36 . 316 36 .144 36 .0 61 Ti 0 . 070 0 .0 30 0 . 0 60 0 .037 0 .102 0 . 0 50 0 .0 33 0 .145 0 .030 0 .093 Al 20.730 20 . 745 20 .345 20 . 30 3 20 .345 20 .731 21 .045 20 .341 21 .130 21 .102 Fe 4.122 c» .884 4 .167 4 . 351 4 .161 4 .242 4 . 315 4 . 40 6 4 . 620 4 . 920 Fe 0.000 0 .000 0 .000 0 .000 0 .000 0 . 000 0 . 000 0 .000 0 .000 0 .000 Mn 32.552 32 .441 32 .523 31 .517 31 .361 cZ. .172 31 . 631 31 . 753 31 .617 31 . 306 Mq 0 .161 0 .176 0 .177 0 .171 0 .177 0 . 136 0 .174 0 .151 0 .171 0 .166 Ca 5.352 5 .525 5 .436 5 . 368 5 . 677 5 .317 5 • C O 5 .516 c r ,_t . 370 t r . 388 Na 0.003 0 .030 0 .018 0 .007 0 .015 0 .003 0 .008 0 . 0 0 0 0 .000 0 .000 38.058 33 . 0 58 38 . 330 38 . 423 33 . 756 37 . 330 38 • t i i 33 0 0 0 33 .133 99 .0 41 Si 5.843 5 . 853 .361 c r _i . 333 5 . 330 c r 0 7 C ; 5 . 833 c r ._\ .345 5 .324 c r .913 Ti 0 . 003 0 .010 0 .007 0 .012 0 .013 0 . 0 0 6 0 . 010 0 .013 0 . 01 0 0 .012 Al 4.075 4 .0 72 4 .0 77 4 . 057 4 . 0 71 4 . 0 73 4 . 0 86 4 . 041 4 . 0 32 4 .0 32 Fe 0 . 575 0 .541 0 .576 0 . 60 2 0 . 574 0 .531 0 .534 0 . 603 0 . 633 0 .675 Fe 0.000 0 .0 00 0 .000 o . 0 0 0 0 .000 0 .000 0 .000 0 .000 0 . 0 0 0 0 .000 Mn 4. 533 4 .577 4 .551 4 . 417 4 . 464 4 . 543 4 . 421 4 .40 3 4 .333 4 . 352 Mq 0 .040 0 .0 44 0 .0 44 0 . 0 42 0 . 0 44 0 . 046 0 . 0 4 3 0 .0 37 0 . 0 42 0 .041 Ca 0 . 356 0 . 336 0 . 373 1 . 0 4 0 1 .003 o . 350 1 .003 0 . 363 0 . 943 0 . 947 Na 0.001 0 .010 0 .006 n . 0 0 2 0 . 0 0 5 o .001 0 .003 0 . 0 0 0 0 . 0 0 0 0 . 00 0 16.104 16 . 038 16 .0 34 16 . 0 66 16 . 0 6 3 16 .033 16 . 0 53 16 .015 16 . 0 23 16 . 0 27 COMPOSITION FM 33.233 33 .155 33 .155 33 .163 33 .142 33 .109 33 .155 33 .270 33 . 1 76 99 .200 AL 3.326 .303 9 g .873 q . 442 3 . 653 q .316 10 .0 55 10 c r c r '-t 11 . 239 PY 0 .643 o . 710 0 . 712 0 .631 0 . 713 0 —?cr . < O O 0 . 70 6 0 . 614 0 .695 0 . 675 SP 74.537 74 c r *~* •—i 74 .133 . 473 . 461 74 .154 f O .013 7 0 t •_' -1 n e r • • C ' - 7 0 . 133 72 .436 GR 15.300 15 .811 15 . 663 16 .774 16 .133 15 .343 16 . 305 15 . 678 15 .467 15 .463 AD 0 .123 n .147 0 .103 0 .173 0 .187 0 .0 32 0 .154 0 . 268 0 .148 0 .132 IJV 0 .000 0 .000 0 .000 0 .000 0 .000 0 . 0 0 0 0 .000 0 . 000 0 .000 0 .000 Major elements i n % Analy s e s by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. ^ NJ APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP009 R221 PINK Si 35 . 995 36 .112 36 .0 50 36 .117 35 .714 35 . ^ 24 35 .323 35 . 534 35 . 360 35 . 30 2 Ti 0 .112 0 .0 83 0 .137 0 . 0 30 0 .073 o . 0 50 0 . 030 0 .0 37 0 .0 35 0 . 0 70 Al 20 .924 20 . 958 20 .937 21 .0 47 20 . 736 20 . 350 20 . 650 20 .716 20 . 654 20 .722 Fe q . 245 •z> . 294 .346 c' . 40 2 . 533 . 241 .141 . 236 . 267 q .234 Fe o . 0 0 0 0 .000 n .000 0 . 0 0 0 0 .000 0 . 0 0 0 0 . 0 0 0 o . 0 0 0 0 . 0 0 0 0 .000 Mr. 34 . 138 34 . 205 34 .023 34 . 40 5 34 .403 34 .445 34 . 233 34 . 266 34 34 .0 53 Mg 0 .0 95 0 . 0 33 0 . 098 0 .035 0 .0 31 0 .031 0 .0 31 0 . 0 70 0 . 0 76 0 .106 Ca 4 .50 4 4 . 559 4 . 643 4 . 753 4 . 613 4 . 543 4 . 623 4 .612 4 . 673 4 . 627 Na n .007 0 .000 0 .000 0 .001 0 . 0 0 3 0 . 0 0 8 0 .001 0 .000 0 .000 0 . 0 0 0 39 .069 99 . 2S<9 99 .234 33 .30 5 93 2 3'-J 33 . 0 48 q q . 813 3 3 . 630 33 . 0 73 33 . 614 Si 5 .925 5 . 930 5 .923 5 . 30 5 c r .331 c r .310 5 . 336 5 . 333 5 .931 5 .325 Ti 0 .014 0 .011 0 .017 0 .011 o . 0 0 3 o . 0 0 6 0 . 010 0 .012 0 .011 0 .003 Al 4 .0 59 4 .0 56 4 .055 4 . 0 55 4 . 0 41 4 .054 4 .0 21 4 .0 43 4 .014 4 .042 Fe 0 .447 0 .452 0 . 460 0 .465 0 .483 0 . 447 0 . 434 0 . 456 0 . 451 0 . 448 Fe 0 .000 0 .000 0 .000 0 .000 0 .000 0 . 0 o 0 0 .000 0 . 0 0 0 0 .000 o . 0 0 0 Mn 4 . 767 4 .758 4 . 735 4 . 764 4 . 803 4 .813 4 . 30 0 4 .812 4 . 799 4 .773 Mq 0 .023 0 .020 0 .024 0 .021 0 .022 0 . 020 0 .022 0 .017 0 .019 0 .0 26 Ca 0 .794 0 .802 0 . 817 0 .834 0 . 816 0 . 30 4 0 . 813 0 .319 0 r-i o - 7 0 . 320 Na 0 .002 0 .000 0 .000 0 .000 0 .003 0 .003 0 .000 0 .000 0 .000 0 .000 16 .031 16 .029 16 .031 16 . 055 16 .073 16 .057 16 . 0 42 16 .0 63 16 . 0 50 16 .044 COMPOSITION: FM 99 .557 99 .612 99 .541 33 . 60 7 33 .573 33 .622 99 .573 33 .674 99 .644 33 .501 AL 7 .416 7 . 506 7 .630 ~> . 653 7 . 363 "7 { .353 7 .143 7 . 473 ~7 . 40 0 -? . 334 PY 0 .335 0 .337 0 .393 0 .333 0 . 366 0 . 329 0 .370 0 O«""' ^ • C~\_'£_ 0 . 30 3 0 .432 SP 79 .147 73 .955 73 . 577 7 0 r .400 73 .441 73 .157 79 .OSO 78 . 927 73 .817 -?f~, { o • »' t GR 12 .845 13 .039 13 .142 13 .443 13 .036 13 .070 13 .253 13 . 140 13 .320 13 . 313 AD 0 .207 0 .163 0 .252 0 .164 0 .134 0 . 092 0 .148 0 . 17S 0 .156 0 .129 UU 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 Major elements i n % Analyses by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y of B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP012 RI12 PINK Si 3 4 . 3 2 2 3 4 . 3 4 2 3 5 . 0 0 2 3 4 . 7 7 5 3 4 . 8 5 3 3 4 . 8 3 9 3 4 . 7 8 3 3 4 . 7 2 6 3 5 . 0 0 4 3 4 . 3 3 1 T i 0 . 2 4 9 0 . 2 6 7 0 . 2 6 7 0 . 2 4 2 0 . 2 1 9 0 . 2 6 4 0 . 2 5 2 0 . 2 3 2 0 . 2 6 0 0 . 3 0 0 Al 1 9 . 2 1 4 1 9 . 0 6 3 1 9 . 1 0 3 1 9 . 2 1 0 1 3 . 3 9 6 1 3 . 4 4 3 1 9 . 3 1 6 1 9 . 2 1 3 1 9 . 3 1 6 1 3 . 2 6 1 Fe tr . 6 6 0 5 . 6 1 3 5 . 9 1 4 6 . 1 7 4 6 . 1 3 0 6 . 2 4 7 5 . 9 9 1 6 . 1 3 2 6 . 4 7 6 6 . 6 4 3 Fe l . 5 7 8 1 . 7 9 8 1 . 7 4 1 1 . 5 3 5 1 . 3 2 9 1 . 2 0 3 1 . 4 1 9 1 . 5 9 2 1 . 4 1 2 1 . 4 6 2 Mn 3 3 . 0 7 0 3 3 . 1 5 8 3 3 . 0 9 7 3 3 . 0 5 4 '" -*"• . 8 6 3 3 2 . 3 4 4 3 2 r*»crt--. o 3 2 . 8 2 5 3 2 . 3 2 4 o o 2 1 6 Mq 0 . 1 6 9 0 . 1 4 9 0 . 1 4 6 0 . 1 6 6 0 . 1 7 9 0 . 1 5 9 0 . 1 5 4 0 . 1 7 4 0 . 1 4 6 0 . 1 7 6 Ca 2 . 8 9 6 3 . 0 3 5 2 . 9 7 5 . 3 1 4 cZ. . 7 6 5 2 . 7 7 3 3 . 0 0 0 2 . 9 0 3 cZ, . 9 5 4 3 . 1 3 1 Na 0 . 0 0 9 0 . 0 0 0 0 . 0 0 3 0 . 0 0 0 0 . 0 0 7 0 . 0 1 2 0 . 0 1 5 0 . 0 2 0 0 . 0 0 0 0 . 0 0 3 9 7 . 6 6 3 9 7 . 9 7 4 9 3 . 2 4 6 3 8 . 0 3 0 3 7 . 7 5 1 9 7 . 7 9 0 9 7 . 7 9 1 9 7 . 3 7 1 9 7 . 8 9 2 3 8 . 1 3 0 Si 5 . 3 9 0 5 . 8 3 3 5 . 8 9 4 cr . 3 7 3 5 . 3 9 0 5 . 8 3 5 5 . 8 7 9 5 . 8 7 1 cr . 3 0 3 cr •J . 3 3 3 T i 0 . 0 3 2 0 . 0 3 4 0 . 0 3 4 o . 0 3 1 0 . 0 2 3 0 . 0 3 3 0 . 0 3 2 0 . 0 2 9 0 . 0 3 3 0 . 0 3 3 Al 3 . 3 3 0 3 . 7 9 4 3 . 7 9 1 3 . 8 2 4 3 . 3 6 2 3 . 8 7 2 3 . 3 4 7 3 . 3 3 0 \j . 8 3 3 3 . 8 2 0 Fe 0 . 3 0 1 0 . 7 9 3 0 . 8 3 3 0 . 3 7 2 0 . 3 6 6 0 . 8 8 2 0 . 3 4 7 0 . 8 7 4 0 . 9 1 3 0 . 3 3 5 Fe 0 . 2 0 1 0 . 2 2 3 0 . 2 2 1 o . 2 0 3 0 . 1 6 9 0 . X J J 0 . 1 3 1 0 . 2 0 2 0 . 1 7 9 0 . 1 3 5 Mn 4 . 7 3 3 4 . 7 4 2 4 . 7 2 0 4 . 7 2 3 4 . 7 0 4 4 . 6 9 9 4 . 7 0 3 4 . 7 0 1 4 . 6 1 7 4 . 5 3 2 Mq 0 . 0 4 3 0 . 0 3 3 0 . 0 3 7 0 . 0 4 2 0 . 0 4 5 0 . 0 4 0 0 . 0 3 9 0 . 0 4 4 0 . 0 3 7 0 . 0 4 4 Ca 0 . 5 2 5 0 . 5 5 8 0 . 5 3 7 0 . 5 0 3 0 . 5 0 1 0 . 5 0 2 0 . 5 4 3 0 . 5 2 6 0 . 5 3 4 0 . 5 6 5 Na 0 . 0 0 3 0 . 0 0 0 0 . 0 0 1 0 . 0 0 0 0 . 0 0 2 0 . 0 0 4 o . 0 0 5 0 . 0 0 7 0 . 0 0 0 0 . 0 0 3 1 6 . 0 6 2 1 6 . 0 7 0 1 6 . 0 6 6 1 6 . 0 3 1 1 6 . 0 6 6 1 6 . 0 7 0 1 6 . 0 7 6 1 6 .*« cr . U C ' -1 1 6 . 0 5 4 1 6 . 0 7 0 COMPOSITION FM 9 9 . 2 6 3 9 9 . 3 5 3 9 9 . 3 7 0 3 3 . 2 8 6 3 3 . 2 2 0 3 9 . 3 0 6 9 9 • C'CL i 9 9 . 2 4 6 9 9 . 3 6 2 3 3 . 2 3 4 AL 1 5 . 9 2 7 1 6 . 1 0 7 1 6 . 6 4 3 1 6 . 3 6 2 1 6 . 5 1 4 1 6 . 5 4 9 1 6 1 7 . 0 0 8 1 7 . 4 5 1 1 7 . 7 3 4 PY 0 . 6 7 3 0 . 5 9 3 0 . 5 7 9 0 . 6 5 3 0 . 7 2 0 0 . 6 4 1 0 . 6 1 7 0 . 6 9 3 0 . 5 o ' 6 0 . 7 0 0 SP 7 5 . 3 4 9 7 4 . 3 1 5 7 4 . 6 1 1 7 4 . 6 3 4 - 7 cr t •-! . 0 4 7 7 5 . 1 1 0 7 4 . 7 3 5 7 4 . 2 6 3 7 3 . 7 5 4 7 2 . 3 1 4 GP. q . 3 0 2 2 . 5 9 3 q . 4 5 2 2 . 5 1 0 3 •—>—'? • cZ> i i O . 5 5 3 . 5 6 6 q . 3 1 2 q . 4 4 0 3 . 6 5 0 AD 5 . 2 4 4 5 . 8 8 7 5 . 7 1 0 5 . 2 3 5 4 . 4 4 2 4 . 1 4 3 4 . 7 6 0 5 . 2 1 3 4 . 7 6 3 4 . , 5 5 3 LV 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 Major elements i n % Anal y s e s by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP054 R202 PINK Si 34 .320 34 .557 34 .679 34 . 5 3 4 34 . 4 6 3 34 . 6 8 8 35 . 2 0 5 35 .045 34 .313 35 .141 Ti 0 .130 0 .175 0 .165 0 .110 0 .133 0 .153 0 .110 0 .133 0 .125 0 .103 Al 1 3 .334 13 .833 1 9 .964 1 9 . 7 9 6 13 . 8 0 3 13 .855 1 3 . 3 3 3 19 .826 1 9 .875 20 .157 Fe c r .363 4 .377 4 .599 4 .117 4 .267 .313 4 . 2 3 5 q . 921 4 . 2 6 5 4 . 8 5 3 Fe 0 . 5 2 3 0 . 530 0 .497 0 .307 0 . 760 0 .676 0 .512 0 .739 0 . 6 7 7 0 . 2 6 4 Mn 36 .516 36 .534 36 .604 36 . 8 9 3 36 . 3 4 6 ^ ~? O t . 0 0 0 37 .2 3 3 Z>P,7 37 .20 3 36 . 3 5 5 Mq 0 .174 0 .153 0 .114 0 .116 0 .113 0 .136 0 .113 0 .134 0 .113 0 .141 Ca 0 .442 0 . 5 3 2 0 . 5 4 3 o . 5 9 6 0 . 6 6 3 0 . 6 6 2 0 "7 O o o .714 0 . 771 0 .757 Na 0 .000 0 .005 0 .004 0 .012 0 .003 0 .000 0 . 0 0 0 0 .000 0 .000 0 .016 3 7 .464 37 .486 97 .169 9 6 . 9 8 6 3 7 .163 3 7 .0 3 8 38 .201 9 7 .80 5 97 . 3 4 3 38 . q q q Si 5 .345 c r •_P .374 c r .900 5 .392 c r .875 5 . 30 4 5 . 3 2 5 c r . 9 2 2 c r ._! .301 5 . 30 7 Ti 0 .023 0 .0 22 o .0 21 0 .014 0 . 01 3 0 . 0 20 0 .014 0 .013 0 .016 0 .013 Al 4 .001 O •-J .386 4 .003 3 .931 .380 l-J ."I "I q . 3 6 6 .943 3 . 3 5 3 o .393 Fe 0 . 7 6 5 0 . 70 7 0 . 6 5 4 0 . 5 8 7 0 . 60 8 o t r t r j q 0 . 5 9 6 o . 554 0 . 60 3 0 . 6 3 2 Fe 0 .0 63 0 .0 7 5 0 .0 64 0 . 10 4 o . 0 38 o .0 37 0 . 0 65 o .0 94 0 . 0 36 0 • 0 %TJ J Mn 5 . 2 6 3 c r . 2 6 8 5 . 2 7 4 c r . 3'3c2 c r O -~ ^ 5 . 3 3 4 c r . 3 1 7 5 C; O ~? 5 . 3 2 6 5 .262 Mq 0 .044 0 . 0 40 0 .029 0 . 0 30 0 . 0 30 0 . 0 34 0 . 0 30 0 .0 34 0 .0 28 0 .0 35 Ca 0 .031 0 .097 0 .099 o .10 9 o .121 o .121 o .131 0 .129 0 .140 0 .136 Na 0 .000 0 .002 0 .001 0 .004 0 .001 0 . 0 0 0 0 . 0 0 0 0 .000 0 .000 0 .005 16 .035 16 .072 16 .045 1 6 . 0 52 16 . 0 6 7 16 . 0 4 0 16 .044 16 .0 37 16 .0 5 3 16 . 0 68 COMPOSITION FM 3 3 .281 3 3 .345 9 9 .513 9 9 . 5 1 2 3 3 .50 0 3 3 . 4 2 6 3 3 .502 99 . 4 3 3 33 . 530 39 .413 AL 1 3 .283 1 2 . 5 7 7 11 . 700 11 .107 11 '—i -—i -—» • Z< c l •_» 10 . 4 5 7 10 . 7 8 0 10 . 4 9 5 11 .137 11 . 6 5 3 PY 0 .705 0 . 6 4 1 0 .473 0 . 4 7 4 0 . 4 3 7 0 . 560 0 . 4 3 8 0 .543 0 . 4 5 3 0 c r - ? c r . I -1 SP 34 . 0 56 34 . 640 3 5 . 9 6 4 8 5 . 7 1 6 j ~ r c r 1—1 .537 86 . 5 3 3 36 . 7 2 7 86 . 4 1 3 36 . 0 8 5 35 . 630 GR 0 .000 0 . 01J 0 0 .000 0 .000 0 .000 0 . 0 0 0 0 .211 0 .000 0 .0 00 1 .0 34 AD 1 .355 2 .142 1 .864 > . 70 2 .60 3 2 . 3 3 5 1 .792 . 5 3 9 . 320 1 . 0 0 9 UM 0 .000 0 .000 0 .000 0 .000 0 .000 0 .000 o .000 0 .000 0 .000 0 .000 Major elements i n % Analyses by M. P i r a n i a n , Department o f G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP054 R203 PINK Si 35 .396 35 .415 35 .250 35 .406 35 .077 35 . 374 35 .447 35 .443 35 .243 35 .323 T i 0 .214 0 .230 0 .153 0 .132 0 .165 0 .060 0 .148 0 .152 0 .130 0 .032 Al 20 .40 8 20 .216 20 .039 20 . 223 19 . 933 13 .30 0 13 . 717 13 . 339 13 .218 13 .230 Fe 5 .570 5 . 0 75 4 .494 4 . 654 4 .501 4 . 533 4 .811 4 . 0 76 4 .0 20 3 .851 Fe 0 .000 0 .047 0 . 320 0 .134 0 .474 0 .708 0 .90 7 1 . 489 1 .635 1 .620 Mn 36 . 643 37 .0 31 36 .957 37 . 629 Cf t .340 36 . 337 36 .351 37 .149 36 . 573 37 .133 Mq 0 .159 0 .133 0 .141 0 .131 o .136 0 .133 0 .143 0 .144 0 .113 0 .126 Ca 0 .543 0 .663 0 .653 0 . 676 0 . 735 0 77C • f ( •_• 0 . 795 0 . 873 0 .372 0 .363 Na 0 .004 0 .008 0 .023 0 .009 0 .027 o . 0 0 0 0 . 005 0 .00 3 o .000 0 .000 98 .941 98 .324 98 .085 98 .995 —- • .433 33 . 437 38 . 829 38 .674 37 . 864 33 . 367 Si 5 .911 5 . 923 cr %J . qqi? 5 .917 cr . 398 5 . 337 5 .936 5 .347 tr . 356 5 .346 T i 0 . 0 27 0 .029 0 .019 0 .017 0 . 021 0 . 0 0 8 0 .019 0 .013 o .017 0 .012 Al 4 .016 q .934 3 .984 3 .983 . 960 q . 336 . 391 . 325 q .327 3 .827 Fe 0 .773 o . 710 0 . 633 0 . 650 o . 633 o . 636 o . 674 0 .572 0 . 568 0 .542 Fe 0 . 0 00 0 .006 0 .040 0 .017 0 .0 60 0 . 0 33 0 .114 o .133 0 .214 0 .205 Mn cr ,_r .133 cr u . 246 5 . 263 5 . 326 5 .313 cr . 260 cr i cr . 230 tr •_l . 236 .30 4 Mq 0 .040 0 .0 34 0 .0 35 0 .0 33 0 . 0 34 0 .034 0 .0 37 0 . 0 36 0 .0 23 0 .0 32 Ca 0 .098 o .119 0 .119 0 .121 0 .141 o .140 0 .143 0 .153 0 . 153 0 . 156 Na 0 .001 o .003 0 .007 n . 0 0 3 0 .003 0 .000 o . 0 0 2 o . 0 01 0 . 0 0 0 o .000 16 .053 16 .0 53 16 .033 16 . 0 67 16 . 0 74 16 .041 16 . 0 42 16 . 026 16 . 0 0 5 16 .024 COMPOSITION FM 99 .340 99 .423 99 .403 99 .459 99 .436 33 .423 99 .391 39 .40 6 33 .530 33 . 480 AL 12 .737 11 . 739 11 .063 10 • O / £l 11 • C_ C_ •_« 11 . 778 12 . 623 11 . 322 12 .257 11 . 674 PY 0 .651 0 . 563 0 .531 0 .532 0 .552 0 . 553 0 .530 0 . 566 0 .445 0 .434 SP 85 .212 86 . 034 86 . 598 86 . 7o7 3 6 .133 i- cr O . 377 83 . 763 r-i .813 . 0 30 82 . 360 GR 0 .952 1 .090 0 .472 1 .155 0 . 326 0 . 0 0 0 0 .000 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 AD 0 .397 0 .574 1 .286 0 . 655 1 .761 . 287 3 .013 4 . 635 cr . 263 4 UU 0 .000 0 .000 0 .000 0 .000 o .000 0 .000 0 .000 0 .000 0 .000 0 .000 Major elements i n % Analyses by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP054 R204 PINK Si 35 . 426 34 .324 35 .032 35 .133 35 . 0 79 34 . 330 35 . 242 35 .023 35 .162 T i 0 .162 0 .103 0 .133 0 . 080 0 .127 0 .133 0 .122 0 .113 0 .035 Al 20 .006 13 .845 19 . 639 19 . 630 19 .632 13 .734 20 .117 13 .370 13 . 337 Fe 4 . 230 q . 737 O . 890 .642 c r •—. c r q . 70 3 4 .146 O . 3 7 3 4 . 0 33 Fe 0 .445 0 - 7 *~i -? • ( Z' f 1 .039 1 . 003 1 . 055 0 O O '"I" 0 .303 0 . 544 0 . 633 Mn 33 . 0 39 .305 37 .921 .621 . 364 q .703 37 . 736 . 643 . 623 Mg 0 .109 0 . 0 33 0 .103 0 .108 0 . 0 98 0 . 0 30 0 . 0 35 0 .033 0 . 106 Ca 0 .757 0 .734 0 . 746 0 . 721 0 . 702 0 . 718 0 . 777 0 . 320 0 . 733 Na 0 . 0 01 0 . 0 0 0 0 . 0 0 0 0 .015 0 .007 0 . 0 0 5 0 .008 0 . 0 0 0 0 .020 33 .174 37 . 439 98 .503 98 . 086 98 • - . c r 0 37 . 866 33 . 550 33 . 138 98 .473 Si 5 .916 c r . 907 5 .90 0 5 . 935 c r .915 c r . 30 3 5 . 315 c r . 90 3 c r •J .312 T i 0 .020 o .014 0 .017 0 . 0 1 0 0 . 0 16 0 .013 0 . 0 1 5 0 .014 0 .012 Al -~! . 933 3 .967 3 . 899 .913 .902 0 . 336 71 . 373 . 967 .941 Fe o . 591 0 . 539 0 .543 o . 514 0 . 50 7 0 c r 0 c r 0 c r . • •_' <Z'd 0 . 561 0 c r —7 c r . 1 -J Fe 0 .056 0 .094 0 .132 0 .123 0 .134 0 .112 0 . 0 3*3 0 . 063 0 .0 38 Mr. 5 . 381 5 . 360 5 . 410 5 • O { Z> c r w i . 423 5 . 40 6 5 • - • , - - c r . C' b -_i c r . 375 5 • ~ c r 0 Mg 0 .027 0 . 0 25 0 .026 0 . 0 27 0 . 025 0 .023 0 . 0 24 0 . 0 25 0 .0 27 Ca 0 . 135 0 .142 0 .135 0 .130 0 .127 0 .130 0 .140 0 .143 0 .144 Na 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 .005 0 .002 0 . 0 0 2 0 . 0 0 3 0 . 0 0 0 0 .007 16 .065 16 . 0 47 16 . 0 66 16 . 0 35 16 . 0 50 16 . 0 54 16 . 0 61 16 . 0 63 16 .063 COMPOSITION FM 3 3 .550 33 .589 99 .573 33 . 552 99 . 596 33 .623 33 . 60 7 33 .535 33 .560 AL 10 . 467 10 •-. cr -^ i 10 .739 10 *"t - 7 r\ • C_ i •_' 10 .167 10 .137 10 .112 10 .20 3 10 . 70 5 PY 0 .441 0 .401 0 .403 0 .434 0 . 390 0 .361 0 -1 O c r * ' O ' 0 . 405 0 .430 SP 37 .097 86 .356 85 .492 86 . 0 65 .023 86 . 432 87 . 373 37 .126 86 .565 GR 0 .342 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 343 0 .373 0 .0 00 AD 1 . 653 2 .439 3 .361 3 .223 . 415 . 350 1 .177 1 O O O • •_• • _ ' ' _ ' . 30 0 UM 0 .000 0 .000 0 .000 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 .000 Major elements i n % Anal y s e s by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP054 R205 PINK S i 34 . 929 34 . 3 3 8 34 ~7 ~? ~7 m i t t 35 . 041 34 . 8 8 9 cr o-_- . 1 1 3 34 . 3 4 6 34 . 942 34 . 771 34 . 636 T i 0 . 1 2 3 0 . 0 3 2 0 . 1 2 2 0 . 1 2 5 0 .0 98 0 .0 37 0 . 1 4 3 0 . 1 3 8 0 . 030 0 . 0 95 A l 19 . 936 13 . 8 3 8 19 . 654 19 . 360 13 . 7 1 7 13 . 373 13 . 668 19 .550 13 . 3 5 3 1 9 . 857 Fe 4 . 339 4 . 0 1 6 . 965 4 . 0 0 7 . 683 4 . 1 2 7 4 . 010 O . 910 q . 731 3 . 837 Fe 0 . 539 • 0 . 7 7 3 1 . 0 2 7 0 . 70 4 0 . 951 0 . 543 0 . 331 1 . 1 6 8 0 . 7 3 3 0 . 736 Mn 37 . 724 . 326 33 . 0 0 2 . 311 -1 —* . 973 .0 32 •—1 ~? •_• f . 30 0 -Z' {' . 5 4 7 3 ~? . 336 3 7 . Ci 1—1 '-> Z, c_ Mq 0 . 093 0 .10 3 0 . 114 0 . 1 0 3 0 . 1 1 8 0 . 0 33 0 . 0 86 0 .0 96 0 . 1 0 3 0 . 0 91 Ca 0 . 805 0 . 765 0 . 302 0 . 7 3 2 0 . 773 0 . 813 0 . 3 3 3 0 . 80 0 0 . 757 0 . 783 Na 0 . 0 1 3 o . 0 0 3 0 . 026 0 . 0 0 7 0 . 0 1 8 0 . 0 0 5 0 . 0 1 5 0 . 004 0 . 0 1 3 0 . 000 98 . 550 38 . 520 98 .490 98 . 4 5 7 38 .231 38 . 354 38 5 P -•' 93 . 1 5 6 38 .0 63 9 8 . 0 21 S i cr . 380 5 . 8 3 2 ._i . 369 5 . 333 5 . 331 5 . 332 cr . 0 0 t o 5 . 303 5 . 330 5 . 866 T i 0 . 016 0 . 0 1 2 0 . 0 1 5 0 . 016 0 . 012 0 . 0 1 2 0 . 0 1 3 0 . 013 0 . 011 0 . 012 A l . 356 . 936 3 . 90 9 0 . 340 .324 3 . 351 -—1 .•3 . 30 4 •-1 . 333 q . 3 5 3 3 . 963 Fe o .611 0 . 565 0 . 560 0 . 564 0 . 521 0 . 5 7 3 0 . 565 0 . 552 0 . 523 0 . 543 Fe 0 .0 75 0 .0 98 0 .130 0 .0 83 0 .121 0 . 0 63 0 . 124 0 . 143 0 . 034 0 . 094 Mn 5 . 373 5 . 4 0 3 5 . 432 5 . 331 5 .431 5 . 412 cr . 40 7 5 . 373 cr . 443 5 . 443 Mq 0 . 023 0 .0 26 0 . 0 2 9 0 .0 27 0 . 0 30 0 . 022 0 . 0 2 2 0 . 024 0 . 0 2 6 0 . 0 23 Ca o . 1 4 5 0 . 1 3 8 0 . 1 4 5 0 . 1 4 3 0 .141 0 . 1 4 6 0 . 150 0 . 1 4 5 0 . 1 3 7 0 . 143 Na 0 . 004 0 . 0 0 3 0 . 0 0 8 0 . 0 0 2 0 . 0 0 6 0 . 0 0 2 0 . 0 0 5 0 .001 0 . 0 0 6 0 . 0 0 0 16 . 083 16 .0 79 16 . 0 98 16 .0 71 16 . 0 76 16 . 0 85 16 . 0 82 16 . 0 5 8 16 . 033 1 6 . 032 FM 99 . 617 33 . 5 7 7 99 . 532 99 . 5 4 3 33 . 514 33 . 633 33 . 646 99 . 6 0 3 33 . 5 7 5 99 . 623 AL 11 . 0 1 3 10 . 60 5 10 . 8 4 8 10 . 50 3 10 . 134 10 . 423 10 . 90 2 11 .061 q . 361 10 . 173 PY 0 . 374 0 . 4 1 2 0 . 452 0 . 441 0 .471 0 m \-' —1 0 . 3 4 2 0 . 332 0 . 4 1 5 0 . 363 SP 86 . 4 3 2 86 . 468 35 . 40 6 36 . 676 86 • d i' i 36 . 333 35 . 538 84 . 793 - 7 . 139 87 . ,032 GR 0 . 1 5 3 0 . 000 0 .000 0 . 000 0 . 0 0 0 0 . 333 0 . 000 0 . 0 0 0 0 . 000 0 . 0 0 0 AD . 0 2 3 . 5 1 5 3 . 294 2 . 330 O . 0 53 1 . 343 . 2 1 7 . 763 . 425 el 1 ,422 UU 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 . 000 0 . 0 0 0 0 . 000 0 . 000 0 . 000 0 .0 00 0 . , 0 0 0 Major elements i n % Anal y s e s by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. APPENDIX 3: MICROPROBE ANALYSES OF SPESSARTINE KCP054 R206 PINK S i 34 . 3 87 35 . 1 3 5 34 .331 35 . 0 7 5 35 . 4 15 34 . 344 34 . 9 7 9 34 .750 34 . 799 35 .0 63 T i 0 .160 0 . 1 8 2 0 . 1 7 3 0 . 1 3 2 0 . 1 72 0 . 1 65 0 . 1 4 5 0 . 175 0 . 163 0 . 172 A l 13 .351 13 . 736 13 .601 13 . 30 4 13 . 326 13 . 736 19 . 6 1 7 19 . 779 19 .481 19 .539 F e 4 .0 43 q . 7 1 7 q . 60 7 4 . 0 3 7 . 3 .381 3 . 840 q . 524 q . 513 . 633 q . 641 Fe 0 . 527 o . 3 4 3 1 . 0 54 0 . 6 3 2 0 . 71 fa 0 . 859 1 .0 59 o . 778 1 . 253 1 . 154 Mr. O ~? . 383 33 . 1 3 3 37 . 3 5 3 38 . 184 O O . 2 72 qp. . 2 53 O "7 . 9 2 2 O O . 1 73 . 916 . 729 Mg 0 . 133 0 . 1 3 3 0 . 144 0 . 144 0 . 1 23 0 . 123 o . 1 4 3 o . 1 23 0 .139 o .0 95 Ca 0 . 6 35 0 . 722 0 . 740 0 . 7 4 3 0 .300 0 . 739 o . 756 o . 858 0 . 935 0 . 914 Na 0 . 0 0 0 0 .001 0 . 000 0 . 004 0 .011 o .000 o . 0 0 0 0 . 0 C 7 0 .000 0 . 005 38 . 231 38 . 668 98 .111 33 . 861 33 . 316 93 . 60S 98 . 144 98 .160 98 .324 93 . 316 S i 5 . 333 cr .311 5 .301 5 . 3 3 7 cr •-) . 3 13 cr .371 cr . 30 6 cr . 873 5 . 373 cr •_i . 311 T i 0 .020 0 .0 23 0 . 0 2 2 0 . 017 o . 0 22 o . 0 21 o . 0 18 0 . 0 22 0 . 021 0 . 0 22 A l o . 365 3 . 306 o . 30 3 O . 3 37 o .301 3 . 3 13 . 3 03 . 340 z> .378 qp2 Fe 0 . 571 0 cr, -j -j 0 . 510 o . 5 6 7 o . 556 0 .541 o . 4 38 0 . 437 0 . 514 0 . 513 Fe 0 . 0 67 0 . 1 07 o . 134 0 . 0 30 0 . 030 0 .10 3 o . 1 3 5 o . 033 o .153 0 . 146 Mn 5 . 412 cr i . 426 5 . 4 1 7 cr . 4 2 3 5 . 4 1 2 c r . 4 53 cr ._) . 423 cr . 465 cr . 425 cr •_' * 337 Mg 0 . 0 33 0 . 0 33 0 .0 36 0 . 0 36 0 .0 31 o .0 31 0 . 0 36 0 .0 31 0 . 035 0 . 024 Ca 0 .126 o . 130 o . 134 o . 1 35 o . 1 43 0 . 142 o . 1 37 0 . 155 0 . 163 0 . 165 Na 0 .00 0 0 . 0 0 0 o .000 o . 0 01 o . 003 o . 0 0 0 o . 0 0 0 0 . 0 0 2 0 .000 0 . 002 16 .0 73 16 .0 53 16 . 0 57 16 . 087 16 . 0 7 0 16 . 0 33 16 . 0 55 16 .0 35 16 .0 30 16 . 0 52 COMPOSITION FM 33 A cr ^  33 . 455 33 . 40 4 33 . 403 33 . 433 33 . 433 33 . 411 33 . 433 33 .428 33 . 60 3 AL 10 . 236 10 . 0 30 10 . 1 3 7 10 . 351 10 . 344 10 .280 10 . 0 1 3 9 .524 10 . 533 10 . 454 PY o cr --i o . -i-'O o . 530 0 . 5 7 5 0 . 578 0 . 4 83 0 . 4 87 0 . 5 63 0 .494 0 . 543 0 . 376 SP 87 . 2 63 86 . 561 85 . 744 86 . 314 36 . 634 36 --. cr -i r->ir . 351 . 230 34 . 3 87 85 . 373 GR 0 . 0 0 0 0 .000 0 . 0 0 0 0 .000 0 .0 00 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 0 .000 0 . 0 0 0 AD 1 .314 2 . 8 73 . 4 35 . 1 53 2 . 474 .331 . 462 . 632 4 .0 31 q .732 IJ'v' 0 .000 0 .000 0 .00 0 0 .000 0 .0 00 0 . 0 0 0 o .000 0 .000 0 .000 0 . 000 Major elements i n % Analyses by M. P i r a n i a n , Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. U ) 

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