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UBC Theses and Dissertations

Geochemical constraints on the genesis of AG-PB and ZN deposits, Sandon, British Columbia Logan, James Metcalfe 1986

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CJ GEOCHEMICAL CONSTRAINTS ON THE GENESIS OF AG-PB AND ZN DEPOSITS, SANDON, BRITISH COLUMBIA by JAMES METCALFE LOGAN B.SC..BROCK UNIVERSITY, 1977 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF GEOLOGICAL SCIENCES We ac c e p t t h i s t h e s i s as c o n f o r m i n g t o the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA MARCH, 1986 © JAMES METCALFE LOGAN, 1986 ? In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the r e q u i r e m e n t s f o r an advanced degree a t the The U n i v e r s i t y of B r i t i s h C o lumbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n - f o r e x t e n s i v e c o p y i n g of t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by the Head of my Department or by h i s or her r e p r e s e n t a t i v e s . I t i s un d e r s t o o d t h a t c o p y i n g or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . DEPARTMENT OF GEOLOGICAL SCIENCES The U n i v e r s i t y of B r i t i s h Columbia 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5 Date: MARCH, 1986 ABSTRACT D e p o s i t s of S l o c a n m i n i n g camp a r e A g - r i c h , Pb- and Zn-b e a r i n g v e i n s l o c a l i z e d around Sandon, s o u t h e a s t e r n B r i t i s h C o lumbia. These s m a l l t o medium tonnage ( t o 10 6 tonnes) d e p o s i t s occupy a major l o d e / f a u l t system which c r o s s c u t s the r e g i o n a l f o l d s t r u c t u r e of the e n c l o s i n g Upper T r i a s s i c S l o c a n Group. The L a t e J u r a s s i c N e l s o n b a t h o l i t h i n t r u d e s t h i s c l a s t i c sequence and c o n t a i n s fewer and m i n e r a l o g i c a l l y d i f f e r e n t d e p o s i t s than the se d i m e n t a r y u n i t . Ore p a r a g e n e s i s and d e p o s i t - s c a l e m e t a l z o n a t i o n p a t t e r n s f o r the Hallmac d e p o s i t r e v e a l two s t a g e s of s i l v e r m i n e r a l i z a t i o n . An e a r l y s t a g e i s c h a r a c t e r i z e d by e x s o l u t i o n i n c l u s i o n s of s i l v e r - s u l p h a n t i m o n i d e s i n g a l e n a . A l a t e r s t a g e p o s t d a t e s the b u l k of g a l e n a d e p o s i t i o n , and i s c h a r a c t e r i z e d by a n t i m o n y - p o o r / s i l y e r - r i c h s u l p h o s a l t s and a c a n t h i t e . These two s t a g e s of Ag m i n e r a l i z a t i o n r e p r e s e n t r e s p e c t i v e l y the 'wet' s e d i m e n t - h o s t e d and 'dry' b a t h o l i t h - h o s t e d ore c l a s s i f i c a t i o n s of C a i r n e s (1934). 'Dry' o r e s a r e l a t e s t a g e , s p a t i a l l y r e s t r i c t e d t o the b a t h o l i t h or r e l a t e d s t o c k s and p e r i p h e r a l l y d i s t r i b u t e d about the c e n t r a l a r e a of 'wet' ore d e p o s i t s a t Sandon. The l a t e s t a g e m i n e r a l assemblages t h e r e b y e s t a b l i s h a r e l a t i v e l y l a t e r p e r i o d of m i n e r a l i z a t i o n f o r b a t h o l i t h - h o s t e d s t r u c t u r e s than t h o s e w i t h i n the sed i m e n t a r y sequence. L i t h o g e o c h e m i s t r y of the S l o c a n Group and lower-most R o s s l a n d Group i n d i c a t e s a s i n g l e u n i t w i t h i n the S l o c a n , i i the S l a t e b e l t , t o be e n r i c h e d i n Ag, Ba and S. Nowhere i n the s t r a t i g r a p h i c sequence a r e Pb and Zn v a l u e s r e c o g n i z a b l y h i g h e r than average b l a c k s h a l e v a l u e s . The S l a t e b e l t c o n t a i n s s y n / d i a g e n e t i c t r a c e m e t a l s u l p h i d e s of p y r i t e , s p h a l e r i t e , c h a l c o p y r i t e , m i l l e r i t e and g a l e n a . Fe, S and p o s s i b l y t r a c e m e t a l s have been r e l e a s e d d u r i n g c o n t a c t / r e g i o n a l metamorphism of p y r i t i c s e d i m e n t s , i n p a r t accompanying the c o n v e r s i o n of p y r i t e t o p y r r h o t i t e . The S l a t e b e l t c o i n c i d e s w i t h the h i g h e s t s p a t i a l d e n s i t y d i s t r i b u t i o n of v e i n d e p o s i t s a t Sandon; source rock volume c a l c u l a t i o n s suggest i t c o u l d have a c t e d as a s o u r c e bed f o r base and p r e c i o u s m e t a l s i n the v e i n s . P b - i s o t o p e s t u d i e s of l a y e r e d s u l p h i d e s i n the c l a s t i c sequence have e s t a b l i s h e d i n i t i a l i s o t o p e r a t i o s and M-value a p p r o x i m a t i o n s f o r the Upper S l o c a n Group. An e v o l u t i o n a r y p a t h s t a r t i n g a t 1890 Ma ( d e p a r t u r e from the c u r v e of Stacey and Kramers, 1975) w i t h M = 11.1 c o u l d have g e n e r a t e d the 'required 2 0 6 P b / 2 0 ' , P b r a t i o s f o r the v e i n d e p o s i t s a t t 3 = 160 ± 6 Ma. T h i s s u g g e s t s t h a t l e a d and perhaps s i l v e r and z i n c i n e p i g e n e t i c v e i n s was e x t r a c t e d from the c l a s t i c s e d i m e n t a r y sequence d u r i n g emplacement of the L a t e J u r a s s i c N e l s o n b a t h o l i t h . T a b l e of C o n t e n t s ABSTRACT *. i i LIST OF TABLES v i i i LIST OF FIGURES i x ACKNOWLEDGMENTS x i i 1 . GENERAL INTRODUCTION 1 1.1 TECTONOSTRATIGRAPHIC SETTING AND EVOLUTION 2 1 . 2 GEOLOGY 6 1 .3 LITHOLOGY 6 1.3.1 SLOCAN GROUP 6 1.3.2 ROSSLAND GROUP 10 1.3.3 INTRUSIVES 12 1 . 4 STRUCTURE 14 1 .5 METAMORPHISM 17 1.6 MINERALIZATION ..24 REFERENCES CITED 26 2. MINERALOGY AND METAL DISTRIBUTION HALLMAC MINE, SANDON, BRITISH COLUMBIA 30 2.1 INTRODUCTION 30 2.2 GENERAL GEOLOGY 32 2.3 MINE GEOLOGY 34 2.4 PETROLOGICAL SAMPLING PROCEDURES 36 2.5 VEIN MINERALOGY 38 2.6 ORE MINERALS 38 2.6.1 P y r i t e 38 2.6.2 S p h a l e r i t e 39 2.6.3 C h a l c o p y r i t e 39 2.6.4 T e t r a h e d r i t e 40 2.6.5 Galena 40 2.6.6 F r e i b e r g i t e 42 2.6.7 F r e i e s l e b e n i t e 45 2.6.8 A n d o r i t e 45 2.6.9 P y r a r g y r i t e 45 2.6.10 A c a n t h i t e 48 2.7 SUPERGENE MINERALS 48 2.7.1 G o e t h i t e 48 2.7.2 L e p i d o c r o c i t e 48 2.7.3 P y r o l u s i t e , P s i l o m e l a n e and R e l a t e d M i n e r a l s 49 2.7.4 C o v e l l i t e 49 2.7.5 A n g l e s i t e 49 2.7.6 C e r u s s i t e 50 2 .8 GANGUE MINERALS 50 2.8.1 Quartz 50 2.8.2 S i d e r i t e 50 2.8.3 C a l c i t e 51 2.9 MICROSTRUCTURES 51 2.10 PARAGENESIS 53 2.11 METAL DISTRIBUTION 61 2.11.1 ASSAY DATA 61 2.11.2 STATISTICAL ANALYSIS 61 2.11.3 TRIANGULAR PLOTS 64 2.11.4 PLAN AND VERTICAL CONTOURING 68 2. 12 DISCUSSION 72 2.13 CONCLUSIONS . 75 REFERENCES CITED 78 v 3. SULPHIDE MINERALOGY AND TRACE METAL DISTRIBUTION WITHIN UPPER SLOCAN AND LOWER ROSSLAND GROUPS, SLOCAN MINING CAMP, BRITISH COLUMBIA 81 3.1 INTRODUCTION 81 3.2 SULPHIDE MINERALOGY 82 3.3 PARAGENESIS 83 3.3.1 DIAGENETIC SULPHIDES 85 3.3.2 METAMORPHIC SULPHIDES 89 3.3.3 HYDROTHERMAL SULPHIDES 94 3.4 GEOCHEMISTRY 96 3.4.1 SAMPLING AND ANALYTICAL PREPARATION 96 3.4.2 STATISTICAL ANALYSIS 103 3.4.3 TRIANGULAR PLOTS 108 3.5 DISCUSSION 110 3.6 CONCLUSION 118 REFERENCES CITED 120 4. LEAD ISOTOPE ABUNDANCES IN LAYERED SULPHIDES WITHIN THE SLOCAN GROUP AND THEIR BEARING ON GENESIS OF Ag-Pb-Zn-Au VEINS 123 4.1 INTRODUCTION 123 4.2 TECTONOSTRATIGRAPHIC SETTING AND EVOLUTION 124 4.3 GEOLOGICAL SETTING 126 4.4 SAMPLE SELECTION 128 4.5 ANALYTICAL PROCEDURE 137 4.6 LEAD ISOTOPE DATA 139 4.7 DATA INTERPRETATION 141 4.8 DISCUSSION ...149 4.9 CONCLUSIONS ..160 REFERENCES CITED ...162 v i 5. CONCLUSIONS 165 APPENDIX A 1 67 APPENDIX B 170 APPENDIX C 173 v i i LIST OF TABLES TABLE 2-1. T e x t u r e s i m p l y i n g e x s o l u t i o n 41 TABLE 2-2. Means, s t a n d a r d d e v i a t i o n s and t h r e s h o l d s d e t e r m i n e d 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 m e t a l v a l u e s , f o o t w a l l and h a n g i n g w a l l v e i n s 62 TABLE 3-1. S l o c a n r e g i o n a l rock g e o c h e m i s t r y 100 TABLE 3-2. Carbon as t o t a l C and hydrogen from S l o c a n ' S l a t e b e l t * 102 TABLE 3-3. Means, s t a n d a r d d e v i a t i o n s and t h r e s h o l d s d e t e r m i n e d 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 m e t a l v a l u e s , r e g i o n a l rock g e o c h e m i s t r y 104 TABLE 3-4. Mean metal v a l u e s of S l o c a n r e g i o n a l rock g e o c h e m i s t r y . C o m p a r i s i o n s w i t h o t h e r s t u d i e s and average s h a l e s 107 TABLE 4-1. Sample d e s c r i p t i o n and l e a d i s o t o p e r a t i o s from p y r i t e c o n c e n t r a t e s 140 TABLE 4-2A. Thorium, uranium, p o t a s s i u m and l e a d c o n c e n t r a t i o n s of S l o c a n sediments 150 TABLE 4-2B. Thorium, uranium and l e a d c o n c e n t r a t i o n s of S l o c a n s e d i m e n t s , and whole rock l e a d i s o t o p e r a t i o s w i t h c o r r e c t i o n s f o r 165 and 247 Ma 150 TABLE 4-3. Galena l e a d i s o t o p e r a t i o s f o r v e i n d e p o s i t s . . 1 5 7 TABLE 4-4. Lead i s o t o p e r a t i o s f o r R - f e l d s p a r from the Nelso n b a t h o l i t h 1 57 v i i i LIST OF FIGURES F i g . 1 - 1 . R e g i o n a l T e c t o n i c Map of so u t h e r n B r i t i s h Columbia 3 F i g . 1-2. Schematic p l a t e t e c t o n i c model f o r study a r e a l a t i t u d e 5 F i g . 1-3. R e g i o n a l geology of the c e n t r a l S l o c a n m i n i n g camp, showing rock g e o c h e m i c a l , i s o t o p e and p e t r o g r a p h i c sample l o c a t i o n s 9 F i g . 1-4. R e g i o n a l geology of the n o r t h e a s t e r n S l o c a n m i n i n g camp, showing rock g e o c h e m i c a l and p e t r o g r a p h i c sample l o c a t i o n s 11 F i g . 1-5. M i c r o - g r o w t h f a u l t i n g c h a r a c t e r i s t i c of s o f t / w e t - s e d i m e h t d e f o r m a t i o n s t r u c t u r e s . . . 16 F i g . 1-6A. S l a t y c l e a v a g e i n s l a t e from S l o c a n u n i t - 1 19 F i g . 1-6B. C r e n u l a t i o n c l e a v a g e d e v e l o p e d w i t h i n h i n g e of f o l d e d s l a t e s i n S l o c a n u n i t - 1 19 F i g . 1-7. C o n t a c t metamorphic assemblage of m u s c o v i t e , s t a u r o l i t e , a n d a l u s i t e and b i o t i t e 21 F i g . 1-8. F i r s t a p p r o x i m a t i o n c o o l i n g h i s t o r y f o r the N e l s o n b a t h o l i t h 23 F i g . 2-1. L o c a t i o n Map of Hallmac Mine 31 F i g . 2-2. P l a n view of underground w o r k i n g s , Hallmac Mine, Sandon 33 F i g . 2-3. V e r t i c a l s e c t i o n A-A 1, Hallmac Mine, Sandon 35 F i g . 2-4. L o n g i t u d i n a l v e r t i c a l s e c t i o n , Hallmac Mine, Sandon 37 F i g . 2-5A. SEM b a c k s c a t t e r p h o t o m i c r o g r a p h of h i g h - g r a d e ore 44 F i g . 2-5B. L i n e s k e t c h f o r a r e a i n F i g . 2-5A 44 F i g . 2-5C. E n e r g y - d i s p e r s i v e x - r a y s p e c t r a f o r f r e i b e r g i t e I and I I 44 F i g . 2-6A. SEM b a c k s c a t t e r p h o t o m i c r o g r a p h of f r e i e s l e b e n i t e i n g a l e n a 47 F i g . 2-6B. SEM b a c k s c a t t e r p h o t o m i c r o g r a p h of f r e i b e r g i t e i n c l u s i o n s i n g a l e n a 47 F i g . 2-6C. P y r a r g y r i t e i n c l u s i o n s i n g a l e n a , r e f l e c t e d l i g h t 47 F i g . 2-6D. F r e i b e r g i t e d i s t r i b u t i o n p e r i p h e r a l t o s p h a l e r i t e i n g a l e n a ground-mass 47 F i g . 2-7. P a r a l l e l l a y e r s ( d a r k ) of s p h a l e r i t e , f r e i b e r g i t e and p y r i t e g r a n u l e s i n m a t r i x of r e c r y s t a l l i z e d galena52 F i g . 2-8A. G r o w t h - a n n e a l i n g t w i n s i n s p h a l e r i t e porphy roc l a s t s 55 F i g . 2-8B. K i n k bands d e f i n e d by e t c h p i t s 55 F i g . 2-8C. S u t u r e d b o u n d a r i e s between e l o n g a t e g a l e n a g r a i n s 55 F i g . 2-8D. S p h a l e r i t e i n groundmass of a n n e a l e d galena....55 F i g . 2-9. P a r a g e n e s i s Hallmac Mine L i n e diagram 57 F i g . 2-10. Van de Veer P a r a g e n e t i c diagram, Hallmac d e p o s i t 58 F i g . 2-11. P r o b a b i l i t y graph f o r 61 Ag v a l u e s from h a n g i n g w a l l v e i n 63 i x F i g . 2-12. Ag-Zn-Pb T r i a n g u l a r p l o t s of f o o t w a l l , h a n g i n g w a l l and w a l l r o c k , Hallmac Mine 65 F i g . 2-13. Ag-Cu-Pb and Zn-Cu-Pb T r i a n g u l a r p l o t s of f o o t w a l l , Hallmac Mine... 67 F i g . 2-14. H a n g i n g w a l l v e r t i c a l s e c t i o n 69 F i g . 2-15. Contour assay v a l u e s f o r s u b d r i f t 1715 W, A: Ag, B: Log Pb, C: Log Ag/Pb, D: Log Ag/Zn 71 F i g . 3-1. Three d i s t i n c t forms of p y r i t e , I : f r a m b o i d s , I I : open-mesh/porous and I I I : m a s s i v e . . . . 84 F i g . 3-2. P a r a g e n e s i s of s e d i m e n t a r y s u l p h i d e m i n e r a l s , L i n e diagram 86 F i g . 3-3. S t r a t i f o r m s p h a l e r i t e i n t e r g r o w n w i t h c a r b o n a t e and minor g a l e n a 88 F i g . 3-4A. Zoned i n c l u s i o n s of s p h a l e r i t e and r u t i l e i n p y r i t e 91 F i g . 3-4B. S y n k i n e m a t i c p y r i t e p r e s s u r e shadow 91 F i g . 3-4C. P y r i t e cubes i n c l u d e d i n p y r r h o t i t e mass 91 F i g . 3-4D. P y r r h o t i t e as l e n s o i d , i r r e g u l a r masses p a r a l l e l metamorphic f o l i a t i o n 91 F i g . 3-5. P r i m a r y s e d i m e n t a r y c r o s s - b e d d i n g p r e s e r v e d by replacement of l i m y u n i t s by p y r i t e 95 F i g . 3-6. R e g i o n a l geology of the c e n t r a l S l o c a n m i n i n g camp, showing rock g e o c h e m i c a l , i s o t o p e and p e t r o g r a p h i c sample l o c a t i o n s 97 F i g . 3-7. R e g i o n a l geology of the n o r t h e a s t e r n S l o c a n m i n i n g camp, showing rock g e o c h e m i c a l and p e t r o g r a p h i c sample l o c a t i o n s 98 F i g . 3-8. P r o b a b i l i t y graph f o r 69 Ag v a l u e s from s e d i m e n t a r y and v o l c a n i c rock g e o c h e m i s t r y 105 F i g . 3-10A. Ag-Pb-Zn T r i a n g u l a r p l o t s of average p r o d u c t i o n grades S l o c a n m i n i n g camp 109 F i g . 3-1 OB. Ag-Pb-Zn T r i a n g u l a r p l o t s of r e g i o n a l rock g e o c h e m i s t r y , S l o c a n m i n i n g camp 109 F i g . 3-10. Ag-Ni-Co and Pb-Ni-Co T r i a n g u l a r p l o t s of r e g i o n a l rock g e o c h e m i s t r y , S l o c a n m i n i n g camp 111 F i g . 3-11. V a r i a t i o n s i n means and 68 p e r c e n t i l e s of t r a c e — element c o n c e n t r a t i o n s f o r i n f e r r e d s t r a t i g r a p h i c s e c t i o n 116 F i g . 4-1. R e g i o n a l T e c t o n i c Map of s o u t h e r n B r i t i s h Columbia 125 F i g . 4-2. R e g i o n a l geology of the c e n t r a l S l o c a n m i n i n g camp, showing rock g e o c h e m i c a l , i s o t o p e and p e t r o g r a p h i c sample l o c a t i o n s 127 F i g . 4-3A. S t r a t i f o r m l a y e r s and l e n s e s of p y r i t e w i t h i n s l a t e 1 30 F i g . 4-3B. P y r i t e f r a m b o i d s , sample PA-606 130 F i g . 4-3C. V a r i a t i o n s i n s u l p h i d e c h a r a c t e r , sample PA-606 1 30 F i g . 4-4A. S t r a t i f o r m p y r i t e l a y e r s , hand sample CD-1, Cody Ck 133 x F i g . 4-4B. C o n t a c t zone between r e c r y s t a l l i z e d p y r i t e and m o s t l y u n a f f e c t e d sediments 133 F i g . 4-4C. S t r a t i f o r m p y r i t e , hand sample PR-4, Payne Rd.133 F i g . 4-4D. P y r i t e g r a i n s i z e v a r i a t i o n , e x t e n s i o n - f r a c t u r e m i n e r a l i z a t i o n and s t r a t i f o r m , sample PR-4 133 F i g . 4-5A. Carbonaceous s l a t e , hand sample WW-22A, Whitewater Ck 1 36 F i g . 4-5B. SEM b a c k s c a t t e r p h o t o m i c r o g r a p h , s y n k i n e m a t i c p y r i t e o v e r g r o w t h s , sample WW-22A 136 F i g . 4-5C. T e x t u r e of i n d i v i d u a l f r a m b o i d s , SEM b a c k s c a t t e r p h o t o m i c r o g r a p h , sample WW-22A 136 F i g . 4-6. S u l p h i d e - l e a d p l o t of 2 0 7 P b / 2 o a P b vs 2 0 6 P b / 2 0 4 P b d a t a from T a b l e 4-1 143 F i g . 4-7. S u l p h i d e - l e a d p l o t of 2 0 8 P b / 2 0 , , P b vs 2 0 6 P b / 2 0 , , P b d a t a from T a b l e 4-1 145 F i g . 4-8. S u l p h i d e - l e a d p l o t of 2 0 7 P b / 2 0 4 P b vs 2 0 S p b / 2 0 , P b from T a b l e s 4-2B, 4-3 and 4-4 152 F i g . 4-9. S u l p h i d e - l e a d p l o t of 2 0 8 P b / 2 0 4 P b vs 2 0 6 P b / 2 0 a P b from T a b l e s 4-2B, 4-3 and 4-4 154 F i g . 4-10. H i s t o g r a m of c a l c u l a t e d /it-values 159 x i ACKNOWLEDGMENTS T h i s r e s e a r c h was i n i t i a t e d w i t h f u n d i n g from A r c t e x E n g i n e e r i n g S e r v i c e s , Vancouver, B.C., and a N a t u r a l S c i e n c e and E n g i n e e r i n g R esearch C o u n c i l g r a n t t o A. J . S i n c l a i r , whose d i r e c t i o n and encouragement as S u p e r v i s o r i s s i n c e r e l y a p p r e c i a t e d . I a l s o thank D r s . R. L. Armstrong, W. C. Barnes C. I . Godwin and J . V. Ross f o r comments and s u g g e s t i o n s which g r e a t l y improved the f i n a l m a n u s c r i p t . I am g r a t e f u l t o J . F i l l i p o n e , D. P a r k i n s o n , A. Andrew, J . Montgomery and L. G o l d s m i t h f o r i d e a s and c r i t i c a l d i s c u s s i o n s which i n f l u e n c e d my t h i n k i n g throughout t h i s r e s e a r c h . L i n d a Erdman's computing w i z a r d r y , p a t i e n c e and h e i g h t a r e d u l y acknowledged. S p e c i a l thanks a r e extended t o a l l the t e c h n i c a l s t a f f of the Department, e s p e c i a l l y E. Montgomery, B. C r a n s t o n and J . K n i g h t . Gordon Hodge, M. S u l l i v a n and J . Newlands p r o v i d e d d r a f t i n g e x p e r t i s e . I r e s p e c t f u l l y thank the l a t e W. Wheeler of Hallmac Mines L t d . , C a l g a r y , A l t a . , f o r the o p p o r t u n i t y t o stu d y and sample the Hallmac d e p o s i t . x i i 1. GENERAL INTRODUCTION S l o c a n m i n i n g camp i s i n the Omineca C r y s t a l l i n e B e l t i n s o u t h e a s t e r n B r i t i s h Columbia. The camp i s a n o r t h e a s t e r l y t r e n d i n g 25 x 10 km 2 a r e a c e n t e r e d on Sandon, B.C., wh i c h , s i n c e i t s i n i t i a l d i s c o v e r y i n the 1890's has produced 1.6 x 10 9 grams Ag, 0.22 x 10 6 tonnes Pb and 0.24 x 10 6 tonnes Zn. The s i l v e r - r i c h d e p o s i t s occupy ' l o d e s ' which t r e n d e a s t e r l y t o n o r t h e a s t e r l y c r o s s c u t i i n g the r e g i o n a l f o l d s t r u c t u r e of the e n c l o s i n g Upper T r i a s s i c S l o c a n Group. The M i d d l e J u r a s s i c N e l s o n b a t h o l i t h has i n t r u d e d t h e s e sediments and h o s t s a s m a l l p e r c e n t a g e of the v e i n s i n the camp. T h i s s t u d y was i n i t i a t e d t o a s s e s s whether sediments of the S l o c a n and/or Lower R o s s l a n d Groups c o u l d a c t as s o u r c e s f o r the m e t a l s i n the v e i n d e p o s i t s . R e s u l t s a r e p r e s e n t e d i n the form of t h r e e p a p e r s . The f i r s t paper p r e s e n t s m i n e r a l o g y , p a r a g e n e s i s . a n d m e t a l d i s t r i b u t i o n of the Hallmac d e p o s i t . Hallmac a t y p i c a l 'wet-ore' l o d e d e p o s i t , p r o v i d e s a b a s i s f o r u n d e r s t a n d i n g l o d e m i n e r a l i z i n g p r o c e s s e s f o r the camp. The second paper examines s u l p h i d e m i n e r a l o g y and t r a c e m e t a l d i s t r i b u t i o n w i t h i n the upper S l o c a n and lower R o s s l a n d Groups. A 'source bed c o n c e p t ' i s i n v e s t i g a t e d f o r v e i n Ag, Pb and Zn, where the r e l a t i o n s h i p of t r a c e m e t a l c o n c e n t r a t i o n s t o s t a g e s of s u l p h i d e f o r m a t i o n and l i t h o l o g i c u n i t s a r e p r e s e n t e d . The t h i r d paper p r e s e n t s l e a d i s o t o p e d a t a f o r l a y e r e d s u l p h i d e s i n the upper p a r t of the S l o c a n Group. An average l e a d 1 2 i s o t o p e growth c u r v e f o r S l o c a n Group d e s c r i b e s e v o l u t i o n i n a lower jz-environment than the S h a l e - c u r v e (Godwin and S i n c l a i r , 1982). I s o t o p e d a t a suggest t h a t l e a d , and p o s s i b l y Ag and Zn were d e r i v e d from the S l o c a n sedimentary package. The f o l l o w i n g s e c t i o n s p r o v i d e an ov e r v i e w of the geology f o r the S l o c a n m i n i n g camp and a d j a c e n t a r e a s . 1.1 TECTONOSTRATIGRAPHIC SETTING AND EVOLUTION The S l o c a n s i l v e r camp i s i n the Omineca C r y s t a l l i n e B e l t i n s o u t h e a s t e r n B r i t i s h Columbia ( F i g . 1-1). T h i s h i g h - g r a d e metamorphic and g r a n i t e - i n t r u d e d b e l t i s the eastern-most 'metamorphic w e l t ' of Monger and o t h e r s (1982) development of which i s r e g a r d e d as the m a n i f e s t a t i o n of s u t u r i n g 'Intermontane S u p e r t e r r a n e ' t o the a n c i e n t western margin of N o r t h America (Monger et al., 1982; P r i c e et al., 1985). The t e r r a n e - a c c r e t i o n model of Monger and o t h e r s (1982) p r o v i d e s a r e a s o n a b l e framework i n which t o u n d e r s t a n d the geodynamic e v o l u t i o n of s o u t h e a s t e r n B r i t i s h Columbia. P r e - a c c r e t i o n c o n s t r a i n t s i n c l u d e : (1) m i o g e o c l i n a l wedge which d e v e l o p e d a t o p the a u t o c h t h o n , (2) p a r a u t o c h t h o n o u s t e r r a n e s i m m e d i a t e l y o u t b o a r d from (1) and (3) ' s u s p e c t ' , now a c c r e t e d , t e r r a n e s which d e v e l o p e d o u t b o a r d and independent of ( 2 ) . 3 4 R i f t i n g i n the m i d - P r o t e r o z o i c E r a i n i t i a t e d development of an A t l a n t i c - t y p e p a s s i v e margin and d e p o s i t i o n of a m i o g e o c l i n a l assemblage of c r a t o n i c provenance. M i o g e o c l i n e s t r a t i g r a p h y i n d i c a t e s i n t e r r u p t i o n of s h e l f : s l o p e : r i s e f a c i e s d e p o s i t i o n by r i f t i n g i n upper P r o t e r o z o i c and a g a i n i n the e a r l y Cambrian. F o l l o w i n g each r i f t i n g e v e n t , an a d d i t i o n a l p a s s i v e margin sequence was d e p o s i t e d ( G a b r i e l s e , 1985). P a r a u t o c h t h o n o u s t e r r a n e s i n c l u d e a lower P r o t e r o z o i c basement g n e i s s c a l l e d 'Monashee', and 'Kootenay', a lower t o upper P a l e o z o i c sequence d e v e l o p e d o u t b o a r d of the m i o g e o c l i n e h i n g e - l i n e . The Kootenay t e r r a n e r e c o r d s lower t o mid P a l e o z o i c i n t r u s i o n and d e f o r m a t i o n p r i o r t o d e p o s i t i o n of l a t e P a l e o z o i c r o c k s (Read and Wheeler, 1976). C o e v a l s t r a t a of the m i o g e o c l i n e do not r e c o r d t h i s e v e n t . L a t e P a l e o z o i c t o L a t e T r i a s s i c s u s p e c t t e r r a n e s of v o l c a n i c a r c a f f i n i t i e s d e v e l o p e d west of Kootenay t e r r a n e . These t e r r a n e s a r e e n v i s i o n e d as 'a c o l l a g e of o f f - s h o r e a r c s ( Q u e s n e l l i a ) and s u b d u c t i o n complexes (Cache Creek) s e p a r a t e d from the western c r a t o n i c margin by a m a r g i n a l b a s i n ( S l i d e Mountain and o v e r l y i n g T r i a s s i c r o c k s ) . . . ' ( P r i c e et al., 1985). K l e p a c k i and Wheeler (1985) c o r r e l a t e the youngest Kootenay s t r a t a w i t h S l i d e Mountain t e r r a n e and g i v e e v i d e n c e f o r e a s t w a r d d i r e c t e d t h r u s t i n g i n the E a r l y Permian. Cache Creek, Q u e s n e l l i a and S l i d e Mountain t e r r a n e s amalgamated t o form Intermontane s u p e r t e r r a n e by the end of the T r i a s s i c (Monger, 1984). 5 UPPER TRIASSIC C a c h e C r e e k Q U E S N E L L I A " - Slocan " •— 7-WlZl ko Slide M t n . EARLY JURASSIC R o s s l a n d V o l c a n i c s I n t e r m o n t a n e S u p e r t e r r a n e K o ? N e l s o n B a t h o l i t h F i g u r e 1-2. Schematic p l a t e t e c t o n i c model f o r study a r e a l a t i t u d e . Adapted from P r i c e and o t h e r s (1985), Monger (1985) and A r c h i b a l d and o t h e r s (1983). 6 S u p e r t e r r a n e a c c r e t i o n i n the e a r l y J u r a s s i c was marked by d e f o r m a t i o n and metamorphism which c h a r a c t e r i z e d the 9 Omineca C r y s t a l l i n e b e l t . F i g u r e 1-2 d e p i c t s e v o l u t i o n of the N o r t h American margin from L a t e P a l e o z o i c t h r o u g h L a t e J u r a s s i c ( m o d i f i e d from P r i c e et al . , 1985). E a r l y T e r t i a r y e x t e n s i o n a l t e c t o n i c s ( P r i c e et al., 1985) d i s r u p t the e a r l i e r s t r u c t u r a l e v e n t s . 1.2 GEOLOGY The s t u d y area l i e s w i t h i n the w e s t - c e n t r a l margin of the Kootenay A r c , a n o r t h - t r e n d i n g a r c u a t e s t r u c t u r e bounded on the e a s t by the P u r c e l l a n t i c l i n o r i u m and on the west by the Okanagan metamorphic and p l u t o n i c complex ( F i g . 1-1). The c e n t r a l Kootenay a r c c o n s i s t s of pol y p h a s e deformed and metamorphosed sediments and l e s s e r v o l c a n i c r o c k s ( F y l e s , 1967; Hoy, 1980 and A r c h i b a l d et al ., 1983) which i n a g r o s s sense young westward from H a d r y n i a n t o L a t e T r i a s s i c ages (Mathews, 1983). Along t h e western margin, the a r c has been i n t r u d e d by mid t o L a t e J u r a s s i c p l u t o n i s m of b a t h o l i t h i c p r o p o r t i o n s . 1 .3 LITHOLOGY 1.3.1 SLOCAN GROUP The S l o c a n Group c o m p r i s e s a v a r i e t y of i n t e r b e d d e d sediments which i n c l u d e a r g i l l i t e , q u a r t z i t e , s l a t e , l i m e s t o n e and t u f f . R a r e l y p u r e , c o m p o s i t i o n s grade from one 7 l i t h i c - t y p e t o the n e x t , the most abundant b e i n g a q u a r t z i t i c a r g i l l i t e ( Hedley, 1952). S t r u c t u r e s v a r y from massive t o more f i s s i l e and s l a t y . A c o n s p i c u o u s f e a t u r e . . . i s the p r e s e n c e of abundant p y r i t e and carbonaceous matter ( B o y l e , 1968). The t h i c k n e s s of the S l o c a n Group i s c o n t r o v e r s i a l , w i t h e s t i m a t e s r a n g i n g from 2,100 m ( C a i r n e s , 1934) t o 11,300 m ( I r w i n , 1950). Hedley (1952) suggested a t h i c k n e s s ' p o s s i b l y s e v e r a l t i m e s t h a t o f C a i r n e s (2,100m). Simple c a l c u l a t i o n s based on A l c o c k ' s (1930) i n f e r r e d s t r a t i g r a p h y , i g n o r i n g p o s s i b l e r e p e t i t i o n of beds by e i t h e r f o l d i n g or f a u l t i n g g i v e an e s t i m a t e d t h i c k n e s s of 7,000 m. L a c k i n g s t r a t i g r a p h i c markers and ample ex p o s u r e , d e t a i l e d s t r a t i g r a p h y and s t r u c t u r e f o r the camp are unknown; n e v e r t h e l e s s the t h i c k n e s s i s c o n s i d e r a b l e . A l c o c k (1930) s u b d i v i d e d the s e d i m e n t a r y s u c c e s s i o n i n t o 4 u n i t s on the b a s i s of l i t h o l o g i c a l abundance. These r o u g h l y p a r a l l e l the r e g i o n a l s t r u c t u r a l t r e n d and p r o v i d e a c rude s t r a t i g r a p h i c sequence. The o l d e s t u n i t s a r e l o c a t e d i n the n o r t h and g e n e r a l l y younger r o c k s a r e e n c o u n t e r e d towards the southwest ( L i t t l e , 1960). T h i s study d i s t i n g u i s h e s o n l y t h r e e zones, t h a t combine A l c o c k ' s (1930) f i r s t and second i n t o a s i n g l e b a s a l u n i t . The l o w e s t , b a s a l s e c t i o n of the S l o c a n Group ( F i g . 1-3: u n i t - 1 ) c o m p r i s e s a s u c c e s s i o n of s l a t e s c o n t a i n i n g numerous l i m e s t o n e l a y e r s t h a t v a r y i n t h i c k n e s s up t o 60 m; arenaceous and carbonaceous u n i t s a l s o o c c u r . The b u l k of 8 the r o c k s are d a r k , f i s s i l e and a r g i l l a c e o u s . Hedley (1945) c o n c l u d e d t h a t s t r u c t u r a l t h i c k e n i n g of t h i s s e c t i o n was r e l a t e d t o minor s t r u c t u r e s and not i s o c l i n a l f o l d i n g but t h e amount of t h i c k e n i n g c o u l d not be e s t a b l i s h e d by Hedley or subsequent w o r k e r s . M i n e r a l i z a t i o n w i t h i n t h i s zone i s c h a r a c t e r i s t i c a l l y r e p l a c e m e n t s i n l i m e s t o n e s , as a t the Lucky J i m and Whitewater Deep d e p o s i t s . The second l i t h o l o g i c a l u n i t ( F i g . 1-3: u n i t - 2 ) , c h a r a c t e r i z e d by massive and b l o c k y a r g i l l i t e s , q u a r t z i t e s and f e l d s p a t h i c s andstone, i s s e p a r a b l e from u n d e r l y i n g r o c k s p r i m a r i l y by the absence of f i s s i l i t y and i t s more arenaceous c h a r a c t e r . T h i s u n i t , g e n e r a l l y more t h i c k l y bedded than the lower or upper u n i t s , c o n t a i n s some of the l a r g e s t ore s h o o t s i n the c a m p — p e r h a p s owing t o i t s more competent n a t u r e . The t h i r d and uppermost rock u n i t ( F i g . 1-3: u n i t - 3 ) , c o n t a i n s t h i n i n t e r b e d s of a r g i l l i t e , l i m y s t r a t a and t u f f a c e o u s h o r i z o n s . The t u f f s c o n s i s t of r e l i c t p l a g i o c l a s e c r y s t a l s and p o r p h y r i t i c m e t a v o l c a n i c and a r g i l l a c e o u s or l i m y rock fragments w i t h i n an opaque m a t r i x of c l a y ± v o l c a n i c ash. D i s t i n c t i o n i n o u t c r o p from q u a r t z i t e i s d i f f i c u l t . Weathered s u r f a c e s r e v e a l i n g p l a g i o c l a s e c r y s t a l o u t l i n e s and the commonly c a l c a r e o u s n a t u r e of the t u f f s a i d s f i e l d i d e n t i f i c a t i o n . A l c o c k (1930) r e g a r d s the abundant i n t r u s i o n s p a r a l l e l t o bedding as p a r t i c u l a r l y c h a r a c t e r i s t i c of t h i s zone. REGIONAL GEOLOGY AND SAMPLE LOCATION MAP (I) LOCATION MAP "f STUDY AREA WASHINGTON LEGEND |; ;;| Btotite quartz mom o nits Feldspar porphyry Nelson granodlorti (porphyritfc) | | Slocan Group claatlc sediments • P«nd*orT EE NwnoLaha metatedlmentB £tJJ Martin conglomerate 1^3 K«»»o Group volcanlcs SLOCAN LITHOLOGICAL SUCCESSION Slate with limestone beda SYMBOLS A Geochemical sample location ® Pyrite Pb-isotope sample location Geological contacts (defined, assumed) Lithological conlacts Lode trends " ™ Fault (dellned. assumed) Geology compllad fi Calinaa 1934 Hadlay. 1949 and 1053 Klapacki and Wh«ak>'. 10 Figure 1-3. Regional geology of the cen t r a l Slocan mining camp, showing rock geochemical, Isotope and petrographic sample l o c a t i o n s . 10 A prominent b e l t of s l a t e s t r a c e a b l e f o r 8 km from Three F o r k s t o s o u t h of Cody ( F i g . 1-3) i s p r o b a b l y a s e p a r a t e u n i t or zone. The p a u c i t y of l i m e s t o n e p r e c l u d e s i n c l u d i n g t h i s b e l t of r o c k s w i t h U n i t 1. L a t e T r i a s s i c , C a r n i a n and N o r i a n conodont faunas have been d e s c r i b e d r e c e n t l y by Or c h a r d (1985) from lower s e c t i o n s of the s e d i m e n t a r y sequence ( u n i t - 1 ) . In a d d i t i o n , conodonts from the u n d e r l y i n g M a r t i n conglomerate i n d i c a t e a l a t e - E a r l y Permian age ( O r c h a r d , 1985), thus s e p a r a t i n g t h i s g r e e n s t o n e conglomerate from the L a t e T r i a s s i c S l o c a n Group. P r e v i o u s workers ( C a i r n e s , 1934; Read and Wheeler, 1976; K l e p a c k i , 1983) had a s s i g n e d t h i s u n i t t o the b a s a l S l o c a n . 1.3.2 ROSSLAND GROUP Hyndman (1968) o u t l i n e s a r o u g h l y 13 km l o n g by 3 km wide a r e a u n d e r l a i n by R o s s l a n d Group i n the n o r t h w e s t e r n c o r n e r of the p r e s e n t study a r e a . L i t h o l o g i e s i n c l u d e massive f l o w s , f l o w b r e c c i a s and t u f f s w i t h c o n g l o m e r a t i c t o f i n e c l a s t i c s e d i m e n t a r y i n t e r v a l s . Most p y r o c l a s t i c and se d i m e n t a r y c o n t a c t s a r e g r a d a t i o n a l i n t o one a n o t h e r , both l a t e r a l l y and v e r t i c a l l y . In the R o s s l a n d - T r a i 1 map a r e a , L i t t l e (1982) d e f i n e s the R o s s l a n d Group t o i n c l u d e the Ymir Group, A r c h i b a l d F o r m a t i o n , E l i s e F o r m a t i o n and H a l l F o r m a t i o n f o r an ag g r e g a t e t h i c k n e s s of more than 4,200 m. South of Summit Lake ( F i g . 1-4) the upper c o n t a c t i s not known and the lower c o n t a c t c o i n c i d e s w i t h v o l c a n i c f l o w u n i t s , t e n a t i v e l y c o r r e l a t e d w i t h the E l i s e F o r m a t i o n . I f a t REGIONAL GEOLOGY AND SAMPLE LOCATION MAP (II) Figure 1-4. Regional geology of the northeastern Slocan mining camp, showing rock geochemical and petrographic sample l o c a t i o n s . 12 t h i s l o c a t i o n the A r c h i b a l d F o r m a t i o n does u n d e r l y the E l i s e F o r m a t i o n i t has been i n c l u d e d i n the upper S l o c a n ( u n i t 3 ) . Both A r c h i b a l d F o r m a t i o n and the upper S l o c a n a r e t h i n l y l a m i n a t e d , t u f f a c e o u s , a r g i l l a c e o u s s i l t s t o n e s and arenaceous a r g i l l i t e s . L a c k i n g f o s s i l c o n t r o l , no d i s t i n c t i o n can be made. The b a s a l u n i t i s a f l o w b r e c c i a c o m p r i s i n g rounded t o a n g u l a r c l a s t s and b l o c k s (up t o 0.3 m). These fragments a r e m i n e r a l o g i c a l l y i d e n t i c a l t o t h e i r f i n e g r a i n e d m a t r i x and d i s t i n c t o n l y on weathered s u r f a c e s . M a s s i v e f l o w s a r e g e n e r a l l y p o r p h y r i t i c , c o n t a i n i n g a u g i t e and p l a g i o c l a s e p h e n o c r y s t s (up t o 4 mm). P y r o c l a s t i c l a y e r s , c o n t a i n m o s t l y v o l c a n i c m a t e r i a l but a l s o minor l i m e s t o n e , q u a r t z i t e and s i l t s t o n e fragments. These u n i t s a r e i n t e r b e d d e d w i t h s l a t e s and r e d and green conglomerate's. T i p p e r (1984) has d a t e d the s t r a t i g r a p h y of L i t t l e (1982) u s i n g f o s s i l s . T i p p e r c o n c l u d e s the ' v o l c a n o g e n i c and p a r t l y contemporaneous E l i s e and A r c h i b a l d F o r m a t i o n s ' t o be E a r l y and L a t e S i n e m u r i a n age, and the o v e r l y i n g H a l l F o r m a t i o n t o be E a r l y P i i e n s b a c h i a n and E a r l y T o a r c i a n age. 1.3.3 INTRUSIVES Two s e p a r a t e b a t h o l i t h i c g r a n i t o i d b o d i e s o c c u r w i t h i n the study a r e a . The o l d e r , s y n k i n e m a t i c Kuskanax b a t h o l i t h c r o p s out n o r t h of Summit Lake ( F i g . 1-4). The N e l s o n b a t h o l i t h , l a r g e l y p o s t - d a t e s d e f o r m a t i o n and the Kuskanax i n t r u s i v e e v e n t . The n o r t h e r n margin of the N e l s o n b a t h o l i t h and i t s s a t e l l i t e i n t r u s i v e b o d i e s c r o p out s o u t h of 1 3 l a t i t u d e 50°00'N i n the a r e a between S l o c a n Lake and Kootenay Lake f F i g . 1-3). Kuskanax b a t h o l i t h i s an a e g e r i n e - a u g i t e l e u c o q u a r t z monzonite which i n t r u d e s upper P a l e o z o i c t o L a t e T r i a s s i c s e d i m e n t a r y and v o l c a n i c sequences of the Kootenay Arc (Hyndman, 1968; Read, 1973). The b a t h o l i t h i s s y n k i n e m a t i c w i t h r e s p e c t t o second phase p e n e t r a t i v e r e g i o n a l d e f o r m a t i o n (Read, 1973). P a r r i s h and Wheeler (1983) date emplacement of the b a t h o l i t h and c o n s e q u e n t l y the age of second phase d e f o r m a t i o n a t 173 i 5 Ma ( z i r c o n , U-Pb). Nels o n b a t h o l i t h i s a c o m p o s i t e , I - t y p e or h o r n b l e n d e - b i o t i t e s u i t e g r a n i t i c rock of p r e d o m i n e n t l y g r a n o d i o r i t e c o m p o s i t i o n ( L i t t l e , 1960; F y l e s , 1967; Cox, 1979; A r c h i b a l d et al., 1983). Both massive and p o r p h y r i t i c v a r i e t i e s o c c u r . The l a t t e r c o n t a i n s l a r g e p o t a s h - f e l d s p a r m e t a c r y s t s (up t o 5 cm l o n g ) i n a groundmass composed of o r t h o c l a s e and m i c r o c l i n e , p l a g i o c l a s e ( A n 1 5 t o A n 3 0 ) and q u a r t z w i t h h o r n b l e n d e , b i o t i t e and a c c e s s o r y m i n e r a l s . K-Ar model ages (Nguyen et al., 1968), Rb/Sr whole rock i s o c h r o n d a t e s (Duncan et al., 1979) and A r / A r apparent ages ( H a r r i s o n , 1985) i n d i c a t e the age of emplacement i s 160 ± 6 Ma, e a r l y - L a t e J u r a s s i c . P a r t i a l r e s e t t i n g of K/Ar d a t e s by T e r t i a r y p l u t o n i s m has o c c u r r e d a l o n g the n o r t h w e s t e r n margin near S l o c a n Lake ( P a r r i s h , 1984; H a r r i s o n , 1985). S a t e l l i t e s t o c k s and dykes a r e commonly p o r p h y r i t i c (termed ' b i r d ' s eye' by C a i r n e s , 1934). C o m p o s i t i o n s range from g r a n o d i o r i t e t o g r a n i t e . L o c a l l y a prominent f o l i a t i o n 14 i s d e v e l o p e d w i t h i n and p a r a l l e l t o dyke c o n t a c t s . T h i s f o l i a t i o n i s k i n e m a t i c r a t h e r than p r i m a r y f l o w banding. C a i r n e s (1934) r e l a t e d t h e s e i n t r u s i o n s t o the N e l s o n s u i t e of p l u t o n i c r o c k s , but Cox (1979) on the b a s i s of t r a c e element c o n c e n t r a t i o n s d i s t i n g u i s h e d the ' p o r p h y r i e s ' from the main b a t h o l i t h i c phases ( T i 0 2 v s . FeO ( t o t a l ) p l o t s f o r th e s e dyke r o c k s d e f i n e a l i n e a r t r e n d which p l o t s below t h a t of the main b a t h o l i t h ) . R o s s l a n d v o l c a n i c d a t a l i e on the e x t e n s i o n of t h i s l i n e a r t r e n d s u g g e s t i n g a p o s s i b l e magmatic r e l a t i o n s h i p (Cox, 1979). 1.4 STRUCTURE Two major phases of d e f o r m a t i o n have a f f e c t e d the study a r e a . D e f o r m a t i o n i s common t o both S l o c a n and R o s s l a n d group r o c k s and hence i s p o s t - E a r l y J u r a s s i c . The e a r l i e s t r e c o g n i z a b l e event f o l d e d the se d i m e n t a r y s u c c e s s i o n i n t o a l a r g e r e g i o n a l a s y m m e t r i c a l s y n c l i n a l s t r u c t u r e . Hedley (1952) d e s c r i b e s the S l o c a n S y n c l i n e as 'recumbent', Ross and K e l l e r h a l l s (1968) as 'asymmetric, w i t h a n o r t h e a s t e r l y (135° azimuth) a x i a l s u r f a c e , which d i p s 55° n o r t h e a s t ' . S p e c u l a t i o n s on e i t h e r form a r e not the purpose of t h i s s t u d y . The Dryden A n t i c l i n e b o r d e r s the st u d y a r e a t o the n o r t h ( F i g . 1-3) and i s composed c h i e f l y of r o c k s o l d e r than the S l o c a n Group. T h i s p a r a l l e l , a n t i c l i n a l s t r u c t u r e was ge n e r a t e d d u r i n g the M i d d l e J u r a s s i c Columbia Orogeny ( K l e p a c k i , 1985). 1 5 F r a c t u r e and l e s s common s l a t y c l e a v a g e a r e a x i a l p l a n a r t o minor f i r s t phase (F,) f o l d s and d e f i n e a r e g i o n a l n o r t h w e s t e r l y s t r i k i n g f o l i a t i o n . Minor f o l d geometry changes a c r o s s the s y n c l i n e from the s h a l l o w west l i m b t o the g e n e r a l l y s t e e p e r e a s t l i m b . F o l d s t y l e s o u t h of the Sandon a r e a on the west l i m b i s recumbent, i s o c l i n a l t o moderate open F, f o l d s (Hedley, 1952). South of Summit Lake ( F i g . 1-4) and n o r t h of Sandon ( F i g . 1-3), F, f o l d s a r e u p r i g h t t i g h t t o moderate n o r t h v e r g i n g s t r u c t u r e s . D e f o r m a t i o n s t y l e a l s o v a r i e s i n a c c o r d w i t h the s t r a t i g r a p h i c and/or s t r u c t u r a l l e v e l . F l u i d c o n t e n t of w e a k l y ( ? ) compacted upper l e v e l sediments i s r e f l e c t e d i n s o f t sediment s t r u c t u r e s and wet d e f o r m a t i o n f e a t u r e s u b i q u i t o u s t o u n i t 3 ( F i g . 1-5). The low g r e e n s c h i s t grade of r e g i o n a l metamorphism has not produced d e f o r m a t i o n a n i s o t r o p i e s which can be r e l a t e d t o a metamorphic g r a d i e n t . The D, s t r u c t u r a l t r e n d ( C a i r n e s , 1934) swings from g e n e r a l l y n o r t h w e s t e r l y t o n o r t h e a s t e r l y to' meet the n o r t h e r n margin of the N e l s o n b a t h o l i t h a t a p p r o x i m a t e l y r i g h t a n g l e s . Hedley (1952) i n t e r p r e t s 'the marked c u r v a t u r e of f o l d axes' t o a s i n g l e c o n t i n u o u s p r o c e s s of f o l d i n g , which c u l m i n a t e d w i t h i n t r u s i o n and f o r m a t i o n of accomodation s t r u c t u r e s . C h i l d s (1968) d e s c r i b e s two p e r i o d s of ( p o s t - F , ) p e n e t r a t i v e d e f o r m a t i o n and c o n t a c t metamorphism r e l a t e d t o i n t r u s i o n of f i r s t the N e l s o n b a t h o l i t h and the younger Mount C a r l y l e s t o c k . .0.25. cm F i g u r e 1-5. M i c r o - g r o w t h f a u l t i n g , common i n l i t h o l o g i c u n i t - 3 , a re c h a r a c t e r i s t i c of s o f t / w e t sediment d e f o r m a t i o n . Sample from Reco Mo u n t a i n . 1 7 In the Summit Lake area, second phase deformation (D 2) r e f o l d s s t r u c t u r e s along e a s t e r l y axes almost c o - a x i a l to D 1 deformation. A north-south s h o r t e n i n g event c h a r a c t e r i z e s D 2. D 2 f r a c t u r e , c r e n u l a t i o n cleavage and e x t e n s i o n a l f e a t u r e s are l e s s w e l l developed than f i r s t phase s t r u c t u r e s . P o s t - d a t i n g the D 2 event i s an a d d i t i o n a l phase of deformation marked by open f o l d i n g and development of an a x i a l plane c r e n u l a t i o n cleavage. T h i s phase i s w e l l developed only l o c a l l y w i t h i n the area northeast of Sandon. A x i a l s u r f a c e s of f o l d s and p o s s i b l y r e l a t e d f a u l t s plunge moderately to the south and southwest. T h i s phase i s i n t e r p r e t e d as the event which produced the f i s s u r e v e i n s i n the camp. 1.5 METAMORPHISM Low grade metamorphic mi n e r a l assemblages c h a r a c t e r i z e the sediments and v o l c a n i c rocks of the study a r e a . C h l o r i t e grade r e g i o n a l g r e e n s c h i s t f a c i e s i s d e f i n e d by the absence of b i o t i t e and the presence of the f o l l o w i n g assemblages. P e l i t e s : Q u a r t z - m u s c o v i t e - a l b i t e - c a l c i t e ± c h l o r i t e ± carbon V o l c a n i c s : A l b i t e - q u a r t z - c a r b o n a t e - c h l o r i t e ± epidote ± a c t i n o l i t e 18 F i g u r e 1-6. A: S l a t y cleavage i n s l a t e from Slocan u n i t - 1 (near Bear Lake). Dark bands are l a y e r - s i l i c a t e - r i c h bands of muscovite, c h l o r i t e and carbonaceous matter which d e f i n e f o l i a t i o n . S i n g l e g r a i n s of quartz (Q), f e l d s p a r and m u s c o v i t e / s e r i c i t e (L-S) are p a r a l l e l to t h i s f o l i a t i o n . B: C r e n u l a t i o n cleavage developed w i t h i n the hinge of f o l d e d s l a t e s , Slocan Group, u n i t - 1 . Sample i s from Z i n c t o n . 19 20 M u s c o v i t e , c h l o r i t e and carbonaceous s e l v a g e s d e f i n e a p l a n a r f o l i a t i o n . Bedding l a m i n a t i o n i s not everywhere d i s t i n c t and where p r e s e n t o c c u r s a t an a n g l e t o the f o l i a t i o n . S l a t y c l e a v a g e ( F i g . 1-6a) development i s a x i a l p l a n a r t o f o l d s , and where l a t e r d e f o r m a t i o n has r e f o l d e d t h i s , c r e n u l a t i o n c l e a v a g e r e s u l t s ( F i g . 1-6b). T h i s i s p a r t i c u l a r l y common i n the s l a t e b e l t and a l o n g Highway 31-A between Three F o r k s and F i s h Lake. Limestone has r e c r y s t a l l i z e d from m i c r i t i c t o medium g r a i n e d . C o n t a c t metamorphic m i n e r a l assemblages p r o v i d e a means of e s t i m a t i n g l i m i t s on the d e p t h of emplacement f o r i n t r u s i v e b o d i e s . A p p l y i n g C a r m i c h a e l ' s (1978) b a t h o z o n a l scheme i n a manner s i m i l i a r t o A r c h i b a l d and o t h e r s (1983) temperature as w e l l as depth can be e s t i m a t e d . In F i g u r e 1-8 the i n s e t i n d i c a t e s a g r a p h i c a l e s t i m a t e of P and T H 2 0 c o n d i t i o n s of c o n t a c t metamorphic assemblages d e v e l o p e d i n p e l i t i c r o c k s . A l s o shown a r e the f i v e i n v a r i a n t p o i n t based bathograds which d e f i n e the b o u n d a r i e s f o r the s i x bathozones of C a r m i c h a e l (1978). The c o n t a c t a u r e o l e b o r d e r i n g the n o r t h e r n edge of the N e l s o n b a t h o l i t h d e s c r i b e d by C a i r n e s (1934) c o m p r i s e s an assemblage of b i o t i t e - g a r n e t - a n d a l u s i t e d e v e l o p e d i n s l a t e s and a r g i l l i t e s of the S l o c a n Group. T h i s assemblage i n d i c a t e s p r e s s u r e s not g r e a t e r than bathozone 2. C h i l d s (1965) r e p o r t s m i n e r a l assemblages and s u g g e s t s m i n e r a l r e a c t i o n s f o r p e l i t i c metasediments from the c o n t a c t a u r e o l e of Mt. C a r l y l e S t o c k . M u s c o v i t e - g a r n e t - s t a u r o l i t e - a n d a l u s i t e 21 F i g u r e 1-7. C h i a s t o l i t e p o r p h y r o b l a s t s surrounded by a b i o t i t e - r i c h groundmass. S e r i c i t e r i m s c h i a s t o l i t e a t bottom r i g h t . Q u a r t z - f i l i e d p u l l - a p a r t s of c h i a s t o l i t e d e f i n e a p o s t - c o n t a c t metamorphic e p i s o d e of b r i t t l e d e f o r m a t i o n . Sample from lower p o r t a l of Lucky J i m mine. Photomicrograph ( x - p o l a r s ) . 22 and a n d a l u s i t e - s i l l m a n i t e - b i o t i t e - m u s c o v i t e i n d i c a t e p r e s s u r e c o n d i t i o n s near the t r a n s i t i o n from bathozone 2 t o bathozone 3. At Lucky J i m mine, near Z i n c t o n a h o r n f e l s assemblage of m u s c o v i t e - s t a u r o l i t e - a n d a l u s i t e - b i o t i t e ( F i g . 1-7) i s de v e l o p e d a d j a c e n t t o s e r i c i t e a l t e r e d f e l d s p a r p o r p h y r y dykes of p o s t - N e l s o n b a t h o l i t h age (Hedley, 1945; C a r i n e s , 1934). T h i s assemblage s u g g e s t s a t r a n s i t i o n p o s i t i o n between bathozone 2 and bathozone 3. In F i g u r e 1-9 ( i n s e t ) the boxed a r e a i n d i c a t e s a temperature of 525°C c o i n c i d e s w i t h a p r e s s u r e of 0.33 GPa. Assuming d e n s i t y of 2.7 gm/cm3 f o r the c r u s t and 3.3 gm/cm3 f o r the upper mantle, a r e a s o n a b l e p r e s s u r e g r a d i e n t would be 0.3 Kb/km. Thus, c o n t a c t metamorphic assemblages i n e q u i l i b r i u m a t p r e s s u r e s of 0.33 GPa would have formed a t c r u s t a l l e v e l s of (3.3 Kb/0.3 Kb/km) about 10 km. A s i m i l a r l e v e l of i n t r u s i o n ( l e s s than or e q u a l 10 km) i s s u g g e s t e d f o r the n o r t h w e s t e r n p o r t i o n of the b a t h o l i t h by H a r r i s o n (1985). C i t i n g < l 0 A r / 3 9 A r age spectrum a n a l y s e s of h o r n b l e n d e , b i o t i t e and K - f e l d s p a r , he proposes a complex h i s t o r y i n v o l v i n g 1) emplacement of the v a r i o u s p l u t o n s from 153 t o 160 Ma, 2) a t t a i n i n g c r u s t a l l e v e l s ( l e s s than or e q u a l 10 km) which p r e v e n t a o A r l o s s from b i o t i t e between 130 t o 154 Ma, 3) a m i l d T e r t i a r y r e h e a t i n g about 50 t o 60 Ma and 4) c o o l i n g below 140° by 38 Ma. A f i r s t a p p r o x i m a t i o n c o o l i n g h i s t o r y can be c o n s t r u c t e d ( F i g . 1-9) by p l o t t i n g fl0Ar/39Ar d a t e s v s . the b l o c k i n g t e m p e r a t u r e s of r e s p e c t i v e m i n e r a l s . 23 40 80 120 160 Time Ma F i g u r e 1-8. F i r s t a p p r o x i m a t i o n c o o l i n g h i s t o r y f o r the N e l s o n b a t h o l i t h . Ar-Ar d a t e s are p l o t t e d a g a i n s t e s t i m a t e s of c l o s u r e t e m p e r a t u r e s . E r r o r s i n time and temperature dimensions a r e one-sigma.Contact metamorphic assemblages e s t a b l i s h temperature and depth of i n t r u s i o n ( i n s e t a f t e r C a r m i c h a e l , 1978). Square g i v e s approximate p o s i t i o n f o r S l o c a n sediments i m m e d i a t e l y a d j a c e n t t o b a t h o l i t h . 24 B l o c k i n g or c l o s u r e t e m p e r a t u r e s w i t h r e s p e c t t o " 0 A r l o s s f o r h o r n b l e n d e s , b i o t i t e s and K - f e l d s p a r a re 530 ± 15°C, 280 ± 40°C and 130 ± 15°C r e s p e c t i v e l y ( H a r r i s o n and M c D o u g a l l , 1980 and 1982; P a r r i s h and Rod d i c k , 1985). A minimum c o o l i n g r a t e f o r the b a t h o l i t h i s b r a c k e t e d by the tem p e r a t u r e i n t e r v a l 530 ± 40°C t o 280 ± 40°C. The hor n b l e n d e b l o c k i n g t emperature c o i n c i d e s w i t h the tempe r a t u r e of i n t r u s i o n d e f i n e d by bathozone 2 / 3 t r a n s i t i o n . The b i o t i t e b l o c k i n g t emperature c o i n c i d e s w i t h a c a l c u l a t e d ambient temperature f o r sediments s u r r o u n d i n g the b a t h o l i t h . A temperature g r a d i e n t of 25°C /km f o r 10 km s u g g e s t s an ambient temperature of 250°C which i s c o m p a t i b l e w i t h the v e r y low grade of r e g i o n a l metamorphism. These t e m p e r a t u r e s suggest t h a t the b a t h o l i t h had l o s t i t s t h e r m a l i d e n t i t y ( b a t h o l i t h t e m p e r a t u r e = ambient t e m p e r a t u r e ) 30 Ma a f t e r i n t r u s i o n . T h i s i n t e r v a l r e p r e s e n t s the maximum c o o l i n g t i m e . C o n c e i v a b l y f a s t e r c o o l i n g r a t e s f o l l o w e d by "°Ar l o s s r e l a t e d t o a t h e r m a l o v e r p r i n t c o u l d produce the same p a t t e r n . 1.6 MINERALIZATION S l o c a n ore d e p o s i t s a re p r e d o m i n e n t l y A g - r i c h Pb-Zn v e i n s . The v e i n s occupy ' l o d e ' s t r u c t u r e s which t r a n s e c t the r e g i o n a l n o r t h w e s t l y f o l d s t r u c t u r e of the S l o c a n sediments ( F i g . 1-3). L o d e / v e i n a t t i t u d e s v s . p r o d u c t i o n f i g u r e s ( C a i r n e s , 1934) i n d i c a t e t h a t the most p r o d u c t i v e v e i n a t t i t u d e s f o l l o w the n o r t h e a s t e r l y t r e n d i n g j o i n t system. 25 Ore d e p o s i t d i s t r i b u t i o n a l o n g 'Lodes' i s r e s t r i c t e d t o those a r e a s open t o f l u i d s d u r i n g m i n e r a l i z a t i o n . L e ss commonly, where l o d e s i n t e r s e c t r e a c t i v e w a l l r o c k , l i m e s t o n e replacement d e p o s i t s d e v e l o p e d . C a i r n e s ' (1934) c l a s s i f i e d v e i n s a c c o r d i n g t o t h e i r s t r u c t u r e and m i n e r a l o g y . 'Wet' ore i s c h a r a c t e r i s t i c a l l y Pb and Z n - r i c h , w i t h a s i d e r i t e and q u a r t z gangue. These d e p o s i t s average 10,000 t o 100,000 tonnes i n s i z e and occur w i t h i n the sed i m e n t a r y u n i t s . 'Dry' ore i s low i n base m e t a l s u l p h i d e c o n t e n t , r e l a t i v e l y e n r i c h e d i n s i l v e r m i n e r a l s and i s h o s t e d by q u a r t z v e i n s which c r o s s c u t the N e l s o n b a t h o l i t h . The g r e a t e s t p r o d u c t i o n has come from s e d i m e n t - h o s t e d 'wet' o r e s . M i n e r a l i z a t i o n i s b e l i e v e d t o be r e l a t e d t o i n t r u s i o n and t h e r e f o r e e q u i v a l e n t i n age t o the N e l s o n b a t h o l i t h (160 ± 6 Ma) (Reynolds and S i n c l a i r , 1971; Andrew et a l . , 1985). REFERENCES CITED A l c o c k , F. J . 1930. Z i n c and l e a d d e p o s i t s of. Canada G e o l o g i c a l Survey of Canada, Economic Geology S e r i e s No. 8, 406 p. Andrew, A., Godwin, C.I. and S i n c l a i r , A . J . 1984. M i x i n g l i n e i s o c h r o n s : a new i n t e r p r e t a t i o n of g a l e n a l e a d i s o t o p e d a t a from s o u t h e a s t e r n B r i t i s h C olumbia. Economic Geology,.79, pp. 919-932. A r c h i b a l d , D.A., G l o v e r , J.K., P r i c e , R.A., F a r r a r , E. and C a r m i c h a e l , D.M. 1983. Geochronology and t e c t o n i c i m p l i c a t i o n s of magmatism and metamorphism, s o u t h e r n Kootenay Arc and n e i g h b o u r i n g r e g i o n s , s o u t h e r n B r i t i s h C o lumbia. P a r t I : J u r a s s i c t o m i d - C r e t a c e o u s . Canadian J o u r n a l of E a r t h S c i e n c e s , 20, pp. 1891-1913. A r c h i b a l d , D. A., Krogh, T. E., Armstrong, R. L. and F a r r a r , E. 1984. Geochronology and t e c t o n i c i m p l i c a t i o n s of magmatism and metamorphism, s o u t h e r n Kootenay Arc and n e i g h b o u r i n g r e g i o n s , s o u t h e a s t e r n B r i t i s h C o lumbia. P a r t I I : M i d - C r e t a c e o u s t o Eocene. Canadian J o u r n a l of E a r t h S c i e n c e s , 21, pp. 567-583. B o y l e , R. W. 1968. The g e o c h e m i s t r y of s i l v e r and i t s d e p o s i t s . G e o l o g i c a l Survey of Canada, B u l l e t i n 160, 264 p. C a i r n e s , C. E. 1934. S l o c a n m i n i n g camp, B r i t i s h C olumbia. G e o l o g i c a l Survey of Canada, Memoir 173, 137 p. C a r m i c h a e l , D. M. 1978. Metamorphic bathozones and b a t h o g r a d s : a measure of the depth of post-metamorphic u p l i f t and e r o s i o n on the r e g i o n a l s c a l e . American J o u r n a l of S c i e n c e , 278, pp. 769-797. C h i l d s , J . F. 1968. C o n t a c t r e l a t i o n s h i p s of Mount C a r l y l e Stock S l o c a n , B r i t i s h C o l u m b i a . U n p u b l i s h e d MSc. T h e s i s , U n i v e r s i t y of B r i t i s h C o lumbia, Van., 76 p. Cox, J . 1979. The geology of the northwest margin of the N e l s o n b a t h o l i t h , B r i t i s h C olumbia. M.Sc. t h e s i s , U n i v e r s i t y of A l b e r t a , Edm., 95 p. Duncan, I . J . , P a r r i s h , R. P. and Armstrong, R. L. 1979. Rb/Sr geochronology of the p o s t - t e c t o n i c i n t r u s i v e e v e n t s i n the Omineca C r y s t a l l i n e B e l t , s o u t h e a s t e r n B r i t i s h Columbia ( a b s t r a c t ) . C o r d i l l e r a n S e c t i o n of the G e o l o g i c a l A s s o c i a t i o n of Canada, Vancouver, B.C., Program and A b s t r a c t s , p.15 F y l e s , J . T. 1967. Geology of the A i n s w o r t h - K a s l o a r e a , 26 27 B r i t i s h C o lumbia, B.C. Department of Mines and P e t r o l e u m R e s o u r c e s , B u l l e t i n 53, 125 p. G a b r i e l s e , H. 1985. Major d e x t r a l t r a n s c u r r e n t d i s p l a c e m e n t s a l o n g the n o r t h e r n Rocky Mountain Trench and r e l a t e d l i n e a m e n t s i n n o r t h - c e n t r a l B r i t i s h C o l u m b i a , G e o l o g i c a l S o c i e t y of America B u l l e t i n , 96, pp. 1-14. H a r r i s o n , T. M. 1985. Thermal h i s t o r y of the N e l s o n B a t h o l i t h , B r i t i s h Columbia. G e o l o g i c a l S o c i e t y of A m e r i c a , Programs and A b s t r a c t s , C o r d i l l e r a n S e c t i o n , p. 360. Hedley, M. S. 1945. Geology of the Whitewater and Lucky J i m mine a r e a s S l o c a n d i s t r i c t , B r i t i s h Columbia Department of M i n e s , B u l l e t i n 22, 54. p. H e d l e y , M. S. 1952. Geology and ore d e p o s i t s of the Sandon a r e a , S l o c a n m i n i n g camp, B r i t i s h C olumbia. B r i t i s h Columbia Department of Mines and P e t r o l e u m R e s o u r c e s , B u l l e t i n 29, 130 p. Hoy, T. 1980. Geology of the R i o n d e l a r e a , c e n t r a l Kootenay Arc s o u t h e a s t e r n B r i t i s h C o lumbia. B r i t i s h Columbia M i n i s t r y of Energy, Mines and P e t r o l e u m R e s o u r c e s , B u l l e t i n 73, 89 p. Hyndman, S. W. 1968. P e t r o l o g y and s t r u c t u r e of Nakusp map-area, B r i t i s h C olumbia. G e o l o g i c a l Survey of Canada, B u l l e t i n 161, 95 p. I r w i n , A. B. 1951. Mapping complex f o l d s i n the S l o c a n S e r i e s , B r i t i s h C olumbia. T r a n s a c t i o n s of Canadian I n s t i t u t e of M i n i n g and M e t a l l u r g y , 54, pp. 494-501. K l e p a c k i , D. W. 1983. S t r a t i g r a p h i c and s t r u c t u r a l r e l a t i o n s of the M i l f o r d , K a s l o and S l o c a n Groups, R o s e b e r r y Quadrangle, L a r d e a u map-area, B r i t i s h C o l u m b i a , i n C u r r e n t R e s e a r c h , P a r t A, G e o l o g i c a l Survey of Canada, Paper 83-1A, pp. 229-233. K l e p a c k i , D. W. and Wheeler, J . 0. 1985. S t r a t a g r a p h i c and s t r u c t u r a l r e l a t i o n s of the M i l f o r d , K a s l o and S l o c a n Groups, Goat Range Lardeau and N e l s o n map a r e a s , B r i t i s h C o l u m b i a , i n C u r r e n t R e s e a r c h , P a r t A, G e o l o g i c a l Survey of Canada, Paper 85-1, pp. 277-286. L i t t l e , H. W. 1960. N e l s o n map-area, west h a l f , B r i t i s h C o l umbia. G e o l o g i c a l Survey of Canada, Memoir 308, 205 P. L i t t l e , H. W. 1982. Geology of the R o s s l a n d - T r a i 1 map-area, B r i t i s h C o lumbia. G e o l o g i c a l Survey of Canada, Paper 79-26, 38 p. 28 Mathews, W. H. 1983. E a r l y T e r t i a r y r e s e t t i n g of potassium-argon d a t e s i n the Kootenay A r c , s o u t h e a s t e r n B r i t i s h Columbia. Canadian J o u r n a l of E a r t h S c i e n c e , 20, pp. 867-872. Monger, J . W. H., P r i c e , R. A. and Templeman-Kluit, D. J . 1982. T e c t o n i c a c c r e t i o n and the o r i g i n of the two major metamorphic and p l u t o n i c w e l t s i n the Canadian C o r d i l l e r a . Geology, 10, pp. 70-75. Monger, J . W. H. 1984. C o r d i l l e r a n t e c t o n i c s : a Canadian p e r s p e c t i v e B u l l e t i n de l a S o c i e t e G e o l o g i q u e de l a -F r a n c e , 26, pp. 255-278. Nguyen, K. K.,. S i n c l a i r , A. J . and L i b b y , W. G. 1968. Age of the n o r t h e r n p a r t of the N e l s o n b a t h o l i t h . Canadian J o u r n a l of E a r t h S c i e n c e s , 5, pp. 955-957. O r c h a r d , M. J . 1985. C a r b o n i f e r o u s , Permian and T r i a s s i c conodants from the c e n t r a l Kootenay A r c : c o n s t r a i n t s on the age of the M i l f o r d , K a s l o and S l o c a n Groups, i n C u r r e n t R e s e a r c h , P a r t A, G e o l o g i c a l Survey of Canada, Paper 85-1A, pp. 287-300. P a r r i s h , R. R. and Wheeler, J . O. 1983. U-Pb Z i r c o n age of the Kuskanax b a t h o l i t h , s o u t h e a s t e r n B r i t i s h Columbia. Canadian J o u r n a l of E a r t h S c i e n c e s , 20, pp. 1751-1756. P a r r i s h , R. R. 1984. S l o c a n Lake F a u l t : a low a n g l e f a u l t zone bounding the V a l h a l l a G n e i s s Complex, N e l s o n map a r e a , s o u t h e r n B r i t i s h C o l u m b i a , i n C u r r e n t R e s e a r c h , P a r t A, G e o l o g i c a l Survey of Canada, Paper 84-1 pp. 323-330. P a r r i s h , R. R. and R o d d i c k , J . A. 1985. Geochronology and i s o t o p e geology f o r the g e o l o g i s t and e x p l o r a t i o n i s t . G e o l o g i c a l A s s o c i a t i o n of Canada, C o r d i l l e r a n S e c t i o n , S h o r t Course No. 4, 71 p. P r i c e , R. A., Monger, J . W. H. and R o d d i c k , J . A. 1985. C o r d i l l e r a n c r o s s - s e c t i o n , C a l g a r y t o Vancouver, i n F i e l d G uidesa t o Geology and M i n e r a l D e p o s i t s i n the s o u t h e r n Canadian C o r d i l l e r a , e d i t e d by D. Templeman-Kluit, Vancouver '85 M e e t i n g , G e o l o g i c a l S o c i e t y of A m e r i c a , C o r d i l l e r a n S e c t i o n , pp.3-1-3-85. Read, P. B. and Wheeler, J . 0. 1976. Lardeau w e s t - h a l f g e o l o g y map 93E. G e o l o g i c a l Survey of Canada, Open F i l e 432. Read, P. B. 1973. P e t r o l o g y and s t r u c t u r e of P o p u l a r Creek map-area, B r i t i s h C o l u m b i a . G e o l o g i c a l Survey of Canada, B u l l e t i n 193, 144 p. 29 Robinson, M. C. 1948. An a n a l y s i s of the depth problem i n the S l o c a n m i n i n g camp, B r i t i s h Columbia. B.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h C o lumbia, Van., 98 p. Robins o n , M. C. c i r c a 1952. G e o l o g i c a l s e t t i n g and r e l a t i o n s h i p s of the s i l v e r - l e a d - z i n c ore d e p o s i t s of the S i l v e r t o n a r e a , S l o c a n m i n i n g camp. U n p u b l i s h e d Ross, J . V. and K e l l e r h a l s , P. 1968. E v o l u t i o n of the S l o c a n S y n c l i n e i n s o u t h - c e n t r a l B r i t i s h Columbia. Canadian J o u r n a l of E a r t h S c i e n c e s , 5, pp. 851-872. T i p p e r , H. W. 1984. The age of the J u r a s s i c R o s s l a n d Group of s o u t h e a s t e r n B r i t i s h C o l u m b i a , i n C u r r e n t R e s e a r c h , P a r t A, G e o l o g i c a l Survey of Canada, Paper 84-1A, pp.631-632. 2. MINERALOGY AND METAL DISTRIBUTION HALLMAC MINE, SANDON, BRITISH COLUMBIA 2.1 INTRODUCTION S i l v e r - l e a d - z i n c o r e s have been produced from about 140 v e i n d e p o s i t s i n the S l o c a n m i n i n g camp s i n c e the 1890's. D i s c o v e r y of the Hallmac d e p o s i t i n August of 1980 marked the f i r s t s i g n i f i c a n t new d i s c o v e r y i n S l o c a n camp d u r i n g r e c e n t y e a r s . The Hallmac mine i s 1.7 k i l o m e t e r s n o r t h of Sandon, B.C. i n the c e n t r e of the camp ( F i g . 2-1, NTS: 82F/14 and 82K/3). Supergene m a t e r i a l a c c e s s i b l e from s u r f a c e p i t s a c c o u n t e d f o r e a r l y p r o d u c t i o n of hi g h g r a d e Hallmac o r e . Bulk a s s a y s r e p o r t e d 3.3 kg Ag/tonne, 72% Pb, 1.0% Zn and 0.51 g Au/tonne f o r the i n i t i a l shipment of 41 tonnes. ( G o l d s m i t h , 1981). Development c o n t i n u e d s p o r a d i c a l l y f o r the next 3 y e a r s . The mine i s c l o s e d a t p r e s e n t . T h i s study was unde r t a k e n t o examine m e t a l and m i n e r a l d i s t r i b u t i o n p a t t e r n s w i t h i n t h a t p a r t of the 'lode system' a v a i l a b l e f o r s t u d y . In a d d i t i o n , a c o m p a r a t i v e study was made of two s p a t i a l l y d i s t i n c t m i n e r a l i z e d v e i n s , one a l o n g the f o o t w a l l of the l o d e and the o t h e r a l o n g the h a n g i n g w a l l . 30 3 1 1 19« 1 1 18° REVELSTOKE 1 17« 1 16° 51° PENTICTON 3 0 0 k m PACIFIC OCEAN Figure 2 - 1 . Location map of Hallmac mine. Inset map shows location with respect to major physiographic subdivisions of the Canadian Cordillera. 32 2.2 GENERAL GEOLOGY The L a t e T r i a s s i c S l o c a n Group (O r c h a r d , 1985) u n d e r l i e s the Sandon a r e a i n a s t r u c t u r a l l y complex b e l t of t y p i c a l l y a r g i l l a c e o u s r o c k s w i t h s u b o r d i n a t e q u a r t z i t e , l i m e s t o n e and v o l c a n i c ( t u f f a c e o u s ) u n i t s . The p r i n c i p a l s t r u c t u r e w i t h i n the camp i s a r e g i o n a l a s s y m e t r i c a l s y n c l i n e , concave t o the southwest, and r e f e r r e d t o as the 'Slocan S y n c l i n e ' (Hedley, 1952; Ross and K e l l e r h a l s , 1968). I n t r u d i n g the S l o c a n s e d i m e n t s , g e n e r a l l y c o n c o r d a n t w i t h the s t r i k e of be d d i n g , a r e dykes and s i l l s r e l a t e d by C a i r n e s (1934) and Hedley (1952) t o the upper J u r a s s i c N e l s o n b a t h o l i t h (Nguyen et al. , 1968; A r c h i b a l d et al. , 1983). Emplacement of t h i s c o m p o s i t e , p o s t - t e c t o n i c b a t h o l i t h (Duncan et ail . , 1979) has been r e l a t e d s p a t i a l l y and t e m p o r a l l y by many ( C a i r n e s ; 1934, Reynolds and S i n c l a i r , 1971; Cox, 1979; and Andrew et al. , 1984) t o the m i n e r a l i z i n g e v e n t . S l o c a n Ag-Pb-Zn v e i n s a r e m i n e r a l i z e d p a r t s of a system of i n t e r c o n n e c t e d and i n many c a s e s m u l t i s t r a n d e d breaks or l o d e s ( R o b i n s o n , 1950) which t r e n d e a s t e r l y t o n o r t h e a s t e r l y c r o s s c u t t i n g the r e g i o n a l f o l d s t r u c t u r e of the e n c l o s i n g s t r a t a . V e i n s o c c u r a l o n g t h e s e l o d e s where d i l a t i o n c o i n c i d e d i n time w i t h the m i n e r a l i z i n g e v e n t ( s ) . F i g u r e 2-2. P l a n view of underground workings, Hallmac mine, Sandon. showing l o c a t i o n of s i n g l e and composite samples. Symbols d i s t i n g u i s h hangingwall v e i n ( • ) and w a l l r o c k ( • ) from f o o t w a l l v e i n ( • ) and w a l l r o c k ( A ) samples. 34 2.3 MINE GEOLOGY At the time of sa m p l i n g the Hallmac l o d e had been de v e l o p e d over a h o r i z o n t a l l e n g t h of 75 metres and v e r t i c a l d i s t a n c e of 50 metres. Workings c o m p r i s e d two a d i t l e v e l s w i t h the l o d e b e i n g e x p l o r e d by f o u r s u b d r i f t s t o t a l l i n g n e a r l y 250 metres i n l e n g t h ( F i g . 2-2). The dominant l i t h o l o g y e n c o u n t e r e d underground i s massive a r g i l l i t e , i n p a r t s h a l y and t h i n bedded. P o r p h y r i t i c d a c i t e has i n t r u d e d the se d i m e n t a r y sequence p e n e c o n c o r d a n t l y w i t h the bedding. D a c i t e a l s o l o c a l l y o c c u p i e s the l o d e s t r u c t u r e , c r o s s c u t t i n g b e d d i n g . W i t h i n the l o d e the d a c i t e i s t y p i c a l l y p y r i t i c , and where f o l i a t e d t y p i c a l l y a l t e r e d . , M i n e r a l i z a t i o n c o n s i s t s of massive pods and l e n s e s of c o a r s e g r a i n e d and l o c a l l y s t e e l g a l e n a e n c l o s e d i n l i m o n i t e - s t a i n e d c l a y gouge' of a l t e r e d c o u n t r y r o c k . Trace amounts of s p h a l e r i t e a r e a l s o v i s i b l e . F o l l o w i n g C a i r n e s ' ( 1 9 3 4 ) d e f i n i t i o n and c l a s s i f i c a t i o n scheme f o r m i n e r a l i z e d s t r u c t u r e s i n the S l o c a n camp, Hallmac i s a ' s h e a r - v e i n l o d e d e p o s i t ' c o n t a i n i n g 'wet' o r e . I t c o m p r i s e s a r o u g h l y 10 metre wide ' l o d e ' s t r u c t u r e , s t r i k i n g 075 degre e s , i n t e r m i t t e n t l y m i n e r a l i z e d by l e a d , z i n c and s i l v e r s u l p h i d e s . The geometry of the l o d e system i s e v i d e n t i n v e r t i c a l s e c t i o n A-A' ( F i g . 2-3). Below 1735 l e v e l m i n e r a l i z a t i o n i s c o n f i n e d t o w a l l s of the f a u l t zone such t h a t s e p a r a t e h a n g i n g w a l l and f o o t w a l l v e i n s a r e r e c o g n i z a b l e . Between th e s e v e i n s the l o d e i s m i n e r a l i z e d o n l y r a r e l y and i s composed of v a r i a b l y sheared c o u n t r y 35 5780 E 5755 E 5760 E 5766 E F i g u r e 2-3. V e r t i c a l S e c t i o n A-A', Hallmac mine, Sandon, showing s t r u c t u r e of l o d e system. Below the Upper l e v e l (1735 m a s l ) the s t r u c t u r e branches i n t o h a n g i n g w a l l and f o o t w a l l v e i n s . 36 r o c k . Above 1735 l e v e l the f o o t w a l l i s not w e l l d e f i n e d and the ' v e i n s ' appear t o merge. Here the e n t i r e w i d t h of the w o r k i n g s c o n s i s t s of t h o r o u g h l y sheared, a l t e r e d c o u n t r y rock t h a t c o n t a i n s s t r i n g e r s and pods of g a l e n a . 2.4 PETROLOGICAL SAMPLING PROCEDURES C h i p s a m p l i n g of the mine was c a r r i e d out d u r i n g the summer of 1983. L a t e r t h a t same year a d d i t i o n a l sample r e j e c t s were p r o c u r e d from the o p e r a t o r s . C h i p samples o b v i o u s l y pose l i m i t s on t e x t u r a l and p a r a g e n e t i c s t u d i e s , though at the o u t s e t of the s t u d y o n l y a c o r r e l a t i o n between m i n e r a l o g y and assay d a t a was sought. In a l l , a t o t a l of 34 p o l i s h e d s e c t i o n s where p r e p a r e d , e i g h t e e n samples from the h a n g i n g w a l l v e i n and 16 from the f o o t w a l l v e i n ( F i g . 2-4). A subset of f i v e samples was s e l e c t e d t o d e t e r m i n e i f r e d i s t r i b u t i o n of ore m i n e r a l s d u r i n g d e f o r m a t i o n c o u l d be r e l a t e d t o m i c r o s t r u c t u r e s . These samples were e t c h e d u s i n g e i t h e r B r e b r i c k and S c a n l o n (1957) e t c h a n t ( f o l l o w i n g the t e c h n i q u e of McClay, 1977), or a s o l u t i o n of KMnO„ + H 2SO„ (as o u t l i n e d i n Ramdohr, 1969) f o r g a l e n a and s p h a l e r i t e r e s p e c t i v e l y . M i n e r a l o g y and p a r a g e n e s i s were e s t a b l i s h e d u s i n g a r e f l e c t i n g m i c r o s c o p e and s c a n n i n g e l e c t r o n m i c r o s c o p e - e n e r g y d i s p e r s i v e X-ray e m i s s i o n s p e c t r o m e t e r u n i t . F i g u r e 2-4. L o n g i t u d i n a l v e r t i c a l s e c t i o n , Hallmac mine, Sandon, showing v e r t i c a l and h o r i z o n t a l d i s t r i b u t i o n of p e t r o g r a p h i c samples. Hangingwal1 ( • ) and f o o t w a l l ( • ). to -j 38 2.5 VEIN MINERALOGY In the Hallmac d e p o s i t o n l y g a l e n a w i t h t r a c e amounts of s p h a l e r i t e and p y r i t e are v i s i b l e i n hand specimen. The gangue c o n s i s t s of c a t a c l a s i t e , q u a r t z , c a l c i t e and s i d e r i t e , a l l of which a r e t h o r o u g h l y a l t e r e d by supergene p r o c e s s e s . No d e c r e a s e i n the amount of o x i d a t i o n i s e v i d e n t w i t h depth. Common v e i n m i n e r a l o g y i s g a l e n a , s p h a l e r i t e , p y r i t e , f r e i b e r g i t e , a c a n t h i t e , p y r a r g y r i t e , c h a l c o p y r i t e and f r e i e s l e b e n i t e . 2.6 ORE MINERALS 2.6.1 PYRITE P y r i t e i s not abundant, o c c u r r i n g p r i m a r i l y as an a c c e s s o r y m i n e r a l w i t h i n v e i n and w a l l r o c k s . V e i n m a t e r i a l c o n t a i n s c u b i c p y r i t e c r y s t a l s up t o 0.25 cm i n s i z e e x h i b i t i n g a l l s t a g e s of hypogene replacement by s p h a l e r i t e , g a l e n a and c a l c i t e . Where o x i d i z e d , p y r i t e i s r e p l a c e d by g o e t h i t e and l e p i d o c r o c i t e . 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 p y r i t e i s i n d i c a t e d by i t s ' f r a c t u r e d appearance and common replacement by o t h e r m i n e r a l s . In s e c t i o n s of deformed o r e , f i n e - g r a i n e d a g g r e g a t e s of u n i f o r m 10 m i c r o n p y r i t e g r a i n s envelope the s u b p a r a l l e l l e n s e s of i n t i m a t e l y i n t e r g r o w n s p h a l e r i t e , f r e i b e r g i t e , p y r i t e and g a l e n a which d e f i n e f o l i a t i o n . These s u b h e d r a l c r y s t a l s may r e p r e s e n t an a d d i t i o n a l ( l a t e ) phase of p y r i t e d e p o s i t i o n . 39 2.6.2 SPHALERITE S p h a l e r i t e , the second most prominent ore m i n e r a l a f t e r g a l e n a , i s d i s t r i b u t e d u nevenly throughout the d e p o s i t . I t o c c u r s as s i n g l e , s m a l l , rounded g r a i n s and l a r g e a n n e a l e d s u b h e d r a l p o r p h y r o b l a s t i c g r a i n s (5 by 2 mm) e x h i b i t i n g a younger replacement t e x t u r e w i t h a l l s i z e / t e x t u r a l g r a d a t i o n s between the two. A l l s p h a l e r i t e e x h i b i t s g r o w t h - a n n e a l i n g t w i n s . F o l i a t i o n i n deformed ore i s d e f i n e d by l a y e r s or l e n s e s of s p h a l e r i t e commonly i n t e r g r o w n or rimmed by f r e i b e r g i t e . C h a l c o p y r i t e o c c u r s w i t h e m u l s i o n t e x t u r e , commonly a l o n g t w i n l a m e l l a e on the {111} p l a n e i n s p h a l e r i t e . In a d d i t i o n , g r a i n boundary e x s o l u t i o n of c h a l c o p y r i t e d e f i n e s t r i p l e j u n c t i o n a n n e a l i n g p o i n t s w i t h i n p o r p h y r b l a s t i c s p h a l e r i t e g r a i n s . L e ss abundant i n c l u s i o n s i n c l u d e t e t r a h e d r i t e and p y r r h o t i t e ( ? ) . S p h a l e r i t e i s r e p l a c e d d o m i n e n t l y by g a l e n a and l a t e c a l c i t e , the l a t t e r p o s s i b l y where c a l c i t e has r e p l a c e d g a l e n a . Where f r a c t u r e d s p h a l e r i t e i s v e i n e d by g a l e n a . T h i s a p p a rent 'replacement', i s l i k e l y the r e s u l t of g a l e n a m o b i l i z a t i o n d u r i n g d e f o r m a t i o n . 2.6.3 CHALCOPYRITE C h a l c o p y r i t e i n a c c e s s o r y amounts, o c c u r s e x s o l v e d w i t h i n s p h a l e r i t e b oth a l o n g t w i n p l a n e s and g r a i n b o u n d a r i e s . Rare minute g r a i n s a r e a l s o l o c a t e d p e r i p h e r a l t o f r e i b e r g i t e . 40 2.6.4 TETRAHEDRITE T e t r a h e d r i t e i s dark o l i v e grey i n r e f l e c t e d l i g h t and s i l v e r - p o o r i n c o n t r a s t t o the more abundant p a l e c o l o u r e d , s i l v e r - r i c h f r e i b e r g i t e . T e t r a h e d r i t e i s r a r e and l i m i t e d i n o c c u r r e n c e t o s m a l l rods and rounded e x s o l u t i o n b o d i e s i n the {111} p l a n e s of s p h a l e r i t e . Noted i n s e v e r a l s e c t i o n s are e x s o l u t i o n rods composed p a r t l y of both t e t r a h e d r i t e and c h a l c o p y r i t e s u g g e s t i n g s i m u l t a n e o u s e x s o l u t i o n of the two. 2.6.5 GALENA G a l e n a , the most abundant s u l p h i d e i n the mine, forms a m a t r i x or groundmass i n which r e l i c t s of e a r l i e r d e p o s i t e d m i n e r a l s occupy i n t e r g r a n u l a r p o s i t i o n s . Galena has embayed p y r i t e and s p h a l e r i t e and appears t o have r e p l a c e d c h a l c o p y r i t e and t e t r a h e d r i t e , as w e l l . P r e f e r e n t i a l replacement of g a l e n a by hypogene c a l c i t e and supergene a n g l e s i t e and c e r u s s i t e i s d i r e c t e d a l o n g c l e a v a g e p l a n e s and/or g r a i n b o u n d a r i e s . S o l i d s o l u t i o n of f r e i b e r g i t e , f r e i e s l e b e n i t e and m i a r g y r i t e ( ? ) i s i n d i c a t e d by l a m e l l a e of t h e s e m i n e r a l s i n the {100} p l a n e s of g a l e n a ( T a b l e 2-1). Rounded and i r r e g u l a r m y r m e k i t i c i n t e r g r o w t h s of f r e i b e r g i t e a r e d i s t r i b u t e d i n t e r s t i a l l y t o g a l e n a g r a i n s . These g e n e r a l l y l a r g e r i n c l u s i o n s (up t o 150 M i n d i a m e t e r ) a r e surrounded by d e p l e t i o n h a l o e s ( F i g . 2-5a), s u g g e s t i v e of an e x s o l u t i o n o r i g i n . A d d i t i o n a l m i n e r a l s i n c l u d e d i n g a l e n a a r e p y r a r g y r i t e , a c a n t h i t e and m i a r g y r i t e ; t h e s e have T a b l e 2-1 T e x t u r e s I m p l y i n g E x s o l u t i o n Sol vent S o l u t e Formulae Form S p h a l e r i t e c h a l c o p y r i t e CuFeS, t e t r a h e d r i t e C u 3 S b S 3 2 5 G a l e n a p y r r h o t 1 t e f r e i b e r g l t e F e 1 - X S 1amel1ae // (100),(111) // (111). twin p l a n e s i n d e f1ni t e (Ag, Cu , Fe JjSbSgjg myrmekit-ic 1amel1ae // ( 100) f r e i e s l e b e n i t e 4PbS.2Ag 2S.2Sb 2S 3 l a m e l l a e // (100) p l a n e s m i a r g y r i t e ' p y a r g y r i t e A g 2 S . S b 2 S 3 3Ag 2S. S b 2 S 3 F r e i b e r g i t e c h a l c o p y r i t e CuFeS 2 a c a n t h i t e Ag 2S a n d o r l t e P b ( A g , C u ) S b 3 S 6 p i a t e l e t s // .(100) rods // ( 100) replacement? replacement? replacement? // p a r a l l e i 1 a l s o as u n o r l e n t e d i n c l u s i o n s s u g g e s t i n g replacement. 42 d i s t r i b u t i o n s and t e x t u r a l r e l a t i o n s h i p s t h a t suggest', a t l e a s t i n p a r t , l a t e d e p o s i t i o n . 2.6.6 FREIBERGITE F r e i b e r g i t e o c c u r s t h r o u g h o u t g a l e n a as e i t h e r rounded or f e a t h e r y m y r m e k i t i c e x s o l u t i o n b o d i e s or rod-shaped 'unmixing b o d i e s ' d i s t r i b u t e d p a r a l l e l t o {100} p l a n e s . G r a i n s i z e f o r the former v a r i e s but averages 20 M i n dia m e t e r w i t h l e n g t h s up t o 200 n common. For those i n c l u s i o n s p a r a l l e l t o the {100} p l a n e g r a i n s i z e s range from minute t o 50 M l o n g rods w i t h e i t h e r e m u l s i o n or s e r i a t e t e x t u r e s ( F i g . 2-5a). V o l u m e t r i c a l l y more i m p o r t a n t , and g e n e r a l l y l e s s than 20 n i n di a m e t e r a r e g r a i n s d i s t r i b u t e d p e r i p h e r a l l y about s p h a l e r i t e ( F i g . 2-6d). In deformed samples c h a r a c t e r i z e d by p o l y g o n i z a t i o n , f r e i b e r g i t e i s l o c a l i z e d a t s u b g r a i n b o u n d a r i e s . These g r a i n s a r e i r r e g u l a r l y shaped and d i s p l a y s e r r a t e d t o l a c e - l i k e complex c o n t a c t r e l a t i o n s h i p s w i t h g a l e n a . Hallmac f r e i b e r g i t e c o n t a i n s v a r i a b l e p r o p o r t i o n s of s i l v e r as i n d i c a t e d s e m i - q u a n t i t a t i v e l y by S.E.M. b a c k s c a t t e r imagery ( F i g . 2-5a). Rough q u a n t i t a t i v e e s t i m a t e s c a l c u l a t e d from e n e r g y - d i s p e r s i v e X-ray s p e c t r a suggest d i f f e r e n c e s of as much as 30% s i l v e r . S i l v e r - r i c h f r e i b e r g i t e c o n t a i n s nummerous i n c l u s i o n s of g a l e n a i n c o n t r a s t t o the s l i g h t l y d a r k e r ( i n b a c k s c a t t e r imagery) c o l o u r of i n c l u s i o n - f r e e , s i l v e r - p o o r f r e i b e r g i t e . Both commonly o c c u r t o g e t h e r i n v a r i o u s s t a g e s of unmixing i n F i g u r e 2-5. A: SEM b a c k s c a t t e r photomicrograph of high-grade ore, showing d e p l e t i o n halo of f r e i e s l e b e n i t e p e r i p h e r a l to 'composite' f r e i b e r g i t e . B: L i n e sketch of area i n (A). Intergrown f r e i b e r g i t e I and II with r e s p e c t i v e a n d o r i t e and a c a n t h i t e decomposition m i n e r a l s . C: E n e r g y - d i s p e r s i v e X-ray s p e c t r a f o r f r e i b e r g i t e I (lower) and II (upper). F r e i b e r g i t e I i s e n r i c h e d i n s i l v e r with respect to I I . 4 4 45 a s s o c i a t i o n w i t h a r g e n t i t e , f r e i e s l e b e n i t e and m i a r g y r i t e . Replacement by c a l c i t e or supergene p r o c e s s e s a r e marked by p a t c h e s of c o v e l l i t e ( F i g . 2-6b). 2.6.7 FREIESLEBENITE F r e i e s l e b e n i t e o c c u r s as rods and rounded e x s o l u t i o n b o d i e s i n the {100} p l a n e of g a l e n a ( F i g . 2-6a). These forms r a r e l y exceed 3 u i n d i a m e t e r o r 40 M i n l e n g t h . Commonly o r i e n t e d a t 90° t o one a n o t h e r , i n t e r s e c t i o n p o i n t s of two b o d i e s a r e marked by n a r r o w i n g , i n d i c a t i v e of e x s o l u t i o n . 2.6.8 ANDORITE A n d o r i t e was i d e n t i f i e d by S.E.M. e n e r g y - d i s p e r s i v e x - r a y s p e c t r a . I t o c c u r r s as i r r e g u l a r - s h a p e d i n t e r g r o w t h s w i t h f r e i b e r g i t e t o 30 M i n s i z e . T e x t u r a l r e l a t i o n s h i p s do not d i s t i n g u i s h whether t h i s m i n e r a l i s p r i m a r y or a replacement of g a l e n a . 2.6.9 PYRARGYRITE P y r a r g y r i t e o c c u r s as rounded, 20 n d i a m e t e r g r a i n s or rods up t o 200 M l o n g , d i s t r i b u t e d i n gal e n a as e i t h e r s o l i t a r y g r a i n s or more commonly as c l u s t e r s of t h r e e t o f o u r g r a i n s ( F i g . 2-6c). A weakly d e f i n e d p r e f e r r e d o r i e n t a t i o n i n the {100} p l a n e of g a l e n a was n o t e d . F i g u r e 2-6. A: SEM b a c k s c a t t e r photomicrograph. Shows s e r i a t e e m u l s i o n t e x t u r e of f r e i e s 1 e b e n i t e i n g a l e n a groundmass. B: SEM b a c k s c a t t e r photomicrograph, Cuspate f r e i b e r g i t e i n c l u s i o n s i n g a l e n a (upper r i g h t ) . W h e r e o x i d i z e d ( l o w e r 1 e f t ) , f r e i b e r g i t e i s rimmed by c o v e l l i t e and r e p l a c e d by c e r u s s i t e . C: R e f l e c t e d p l a n e p o l a r i z e d l i g h t , P y r a r g y r i t e i n c l u s i o n s i n g a l e n a . A n g l e s i t e f i l l s c l e a v a g e p l a n e s , and D: L i n e s k e t c h from photograph, F r e i b e r g i t e d i s t r i b u t e d p e r i p h e r a l t o s p h a l e r i t e i n g a l e n a groundmass. 48 2.6.10 ACANTHITE A c a n t h i t e o c c u r s i n minor amounts a t a l l l e v e l s i n the mine. I t forms l e n t i c u l a r - s h a p e d i n c l u s i o n s up t o 100 u l o n g i n f r e i b e r g i t e and s u b h e d r a l e q u i g r a n u l a r g r a i n s about 15 by 15 /u i n g a l e n a . The l a t t e r o c c u r r e n c e i s a s s o c i a t e d s p a t i a l l y w i t h f r e i b e r g i t e . The m i n e r a l has been r e f e r r e d t o as both a hypogene and supergene m i n e r a l i n the p a s t ( C a i r n e s , 1935; O r r , 1971). A c a n t h i t e was not i d e n t i f i e d as supergene. A c a n t h i t e i s r e p l a c e d by c a l c i t e . 2.7 SUPERGENE MINERALS 2.7.1 GOETHITE G o e t h i t e formed a t the expense of p y r i t e , c h a l c o p y r i t e and s i d e r i t e . C u b i c ( a f t e r p y r i t e ) and rhombic ( a f t e r s i d e r i t e ) pseudomorphs and open-boxwork replacement t e x t u r e s a r e u b i q u i t o u s throughout the mine. 2.7.2 LEPIDOCROCITE L e p i d o c r o c i t e a l s o formed d u r i n g o x i d a t i o n of p y r i t e , i s much l e s s common than g o e t h i t e , and o c c u r s as i d i o b l a s t i c t a b l o i d c r y s t a l s p r e f e r e n t i a l l y a l i g n e d a l o n g f r a c t u r e s w i t h i n g o e t h i t e . C r y s t a l form i s s u g g e s t i v e of open space f i l l i n g w i t h growth d i r e c t e d inwards from both f r a c t u r e w a l l s . 49 2.7.3 PYROLUSITE, PSILOMELANE AND RELATED MINERALS P o l i a n i t e - p y r o l u s i t e (Ramdohr, 1969) o c c u r s as e x t r e m e l y f i n e - g r a i n e d r h y t h m i c i n t e r g r o w t h s w i t h g o e t h i t e or l o c a l i z e d i n minute b r a n c h i n g c r a c k s or c l e a v a g e f r a c t u r e s r e p l a c i n g m a n g a n o s i d e r i t e . P s i l o m e l a n e ( b o t r y o i d a l form) e n c r u s t s g o e t h i t e boxworks of m a n g a n o s i d e r i t e and p y r i t e . S.E.M. e n e r g y - d i s p e r s i v e X-ray s p e c t r a i n d i c a t e l e a d t o be p r e s e n t i n a r h y t h m i c form and c o m p o s i t i o n s u g g e s t i v e of the m i n e r a l c o r o n a d i t e (PbMn.MnO, 6)• 2.7.4 COVELLITE Minute p a t c h e s of f i n e l y - c r y s t a l l i n e c o v e l l i t e o ccur a l o n g the o x i d i z e d margins of g a l e n a . D i s t r i b u t i o n of c o v e l l i t e w i t h i n c e r u s s i t e i s r e l a t e d t o the i n - s i t u o x i d i z a t i o n of any one of the f o l l o w i n g i n c l u s i o n s p r e s e n t i n g a l e n a : t e t r a h e d r i t e , f r e i b e r g i t e , s p h a l e r i t e or c h a l c o p y r i t e ( F i g . 2-6b). These r e l a t i o n s i n d i c a t e t h a t c o v e l l i t e was one of the l a s t m i n e r a l s t o form. 2.7.5 ANGLESITE A n g l e s i t e has r e p l a c e d g a l e n a i n s u r f a c e samples and l e s s p e r v a s i v e l y a t lower l e v e l s i n the mine. I t f i l l s f r a c t u r e s or e n c r u s t s g r a i n s i n r h y t h m i c l a y e r e d t e x t u r e commonly a l t e r n a t i n g w i t h f i n e - g r a i n e d (secondary ?) g a l e n a . In h e a v i l y o x i d i z e d s e c t i o n s of the l o d e , e u h e d r a l c r y s t a l s occupy vugs and c a v i t i e s . 50 2.7.6 CERUSSITE C e r u s s i t e r e p l a c e s g a l e n a a l o n g c l e a v a g e p l a n e s and f r a c t u r e s . I t i s i n t i m a t e l y i n t e r g r o w n or env e l o p e d by a n g l e s i t e which appears t o be l a t e r and r e p l a c i n g c e r u s s i t e . 2.8 GANGUE MINERALS •2.8.1 QUARTZ Qua r t z i s d i s t r i b u t e d t hroughout the v e i n s i n amounts nowhere e x c e e d i n g 20% of the t o t a l gangue. I t o c c u r s p r e d o m i n a t e l y as inward p r o j e c t i n g c r y s t a l s l i n i n g f r a c t u r e s and v e i n w a l l s ( p e r p e n d i c u l a r t o the w a l l s ) . Q u a r t z c r y s t a l s c o n t a i n i n c l u s i o n s of p y r i t e . In deformed samples e u h e d r a l q u a r t z c r y s t a l s appear t o be ' f l o a t i n g ' i n g a l e n a . 2.8.2 SIDERITE The b u l k of the gangue (60%) i s co m p r i s e d of s i d e r i t e , m a n g a n o s i d e r i t e and l e s s e r amounts of r h o d o c h r o s i t e . No d i s t i n c t i o n c o u l d be made among the t h r e e m i n e r a l s d u r i n g p o l i s h e d s e c t i o n work and they a r e d e s c r i b e d t o g e t h e r as s i d e r i t e . S i d e r i t e o c c u r s as c o a r s e l y c r y s t a l l i n e masses, or r a r e l y , i n t e r s t i t i a l t o q u a r t z where the two f i l l f r a c t u r e s . C r y s t a l s of q u a r t z , p y r i t e and g r a i n s of s p h a l e r i t e a r e common i n c l u s i o n s , g a l e n a a l e s s common one. O x i d a t i o n reduces s i d e r i t e t o a m i x t u r e of g o e t h i t e and p y r o l u s i t e and o t h e r Mn o x i d e s which commonly form pseudomorphs w i t h the former rhombic form. 51 2.8.3 CALCITE C a l c i t e , a p p r o x i m a t e l y e q u a l i n abundance t o q u a r t z , i s a l a t e s t a g e m i n e r a l o c c u p y i n g c r o s s c u t t i n g f r a c t u r e s and i n t e r s t i a l p o s i t i o n s t o a l l o t h e r hypogene m i n e r a l s . S e c t i o n s of the l e s s deformed v e i n commonly c o n t a i n c l e a r e u h e d r a l rhombs which occupy vugs w i t h i n the o r e . 2.9 MICROSTRUCTURES P o s t - d e p o s i t i o n a l d e f o r m a t i o n has a f f e c t e d the ore m i n e r a l s v a r i a b l y , depending upon t h e i r r e s p e c t i v e r h e o l o g i e s and l o c a t i o n s w i t h i n the s t r e s s f i e l d . P y r i t e has deformed by b r i t t l e f r a c t u r e . G r a n u l a t i o n has produced p o r p h y r o c l a s t s of s p h a l e r i t e . Where s h e a r i n g has been o p e r a t i v e b o t h p y r i t e and s p h a l e r i t e a r e drawn out i n t o p a r a l l e l s t r i n g s of g r a n u l e s w i t h i n a m a t r i x of g a l e n a ( F i g . 2-7) . S h e a r i n g has a f f e c t e d g a l e n a more n o t i c e a b l y than any of the ore m i n e r a l s . G r a i n s i z e v a r i e s from c o a r s e l y c r y s t a l l i n e (4 by 4 cm 2 cubes) i n zones i s o l a t e d from s h e a r i n g , t o f o l i a t e s t e e l g a l e n a where d e f o r m a t i o n has produced a v a r i e t y of superimposed mi r e s t r u c t u r e s and t e x t u r e s i n a d d i t i o n t o g r a i n s i z e r e d u c t i o n . These t e x t u r e s i n c l u d e dynamic r e c r y s t a l l i z a t i o n , k i n k b a n d i n g , p o l y g o n i z a t i o n , and c u r v e d {001} c l e a v a g e s , the l a t t e r t h r e e b e i n g i n d i c a t i v e of a r e s i d u a l d i s t o r t e d c r y s t a l l a t t i c e . K i n k bands and s l i p p l a n e s i n g a l e n a a r e o u t l i n e d by a h i g h d e n s i t y of e t c h p i t s ( i n d i c a t i v e of edge d i s l o c a t i o n s ) i n 52 Figure 2 - 7 . P a r a l l e l l a y e r s (dark) of s p h a l e r i t e , f r e i b e r g i t e and p y r i t e granules d e f i n i n g mineral l i n e a t i o n in matrix of r e c r y s t a l l i z e d galena (pale ! R e f l e c t e d plane p o l a r i z e d l i g h t . 53 F i g u r e 2-8b. Where p o l y g o n i z a t i o n d e v e l o p e d a d j a c e n t t o p y r i t e or s p h a l e r i t e grains,- s m a l l r e l i c t s u b g r a i n s ( F i g . 2-8d) a r e p r e s e r v e d . D i s t a n t (1 mm) from t h e s e a r e a s of r e l a t i v e l y h i g h s t r a i n , s u b g r a i n s i z e i s markedly l a r g e r . F r e i b e r g i t e and A g - s u l p h o s a l t s d i s p l a y d i f f e r e n t t e x t u r e s and d i s t r i b u t i o n f o l l o w i n g d e f o r m a t i o n . In samples which have undergone d e f o r m a t i o n t h e s e s i l v e r - b e a r i n g m i n e r a l s o c c u r : 1) i n p a r a l l e l l a y e r s i n t e r g r o w n w i t h s p h a l e r i t e , 2) i n t e r s t i a l t o p o l y g o n i z e d g a l e n a , and 3) l o c a l i z e d a l o n g s l i p p l a n e s . Undeformed samples e x h i b i t e x s o l u t i o n b o d i e s of t h e s e m i n e r a l s a l i g n e d p a r a l l e l t o {100} p l a n e s i n g a l e n a , and anala g o u s d i s t r i b u t i o n t o those i n 1) and 2 ) , above. An i n c r e a s e i n the g r a i n s i z e and r e l a t i v e abundance of f r e i b e r g i t e and f r e i e s l e b e n i t e o c c u r s w i t h i n deformed samples, a l b e i t a t the expense of o r i e n t e d e x s o l u t i o n m i n e r a l s (not o b v i o u s i n a n n e a l e d s u b g r a i n s ) . These 'second phase' A g - r i c h i n c l u s i o n s a r e l o c a l i z e d a t t r i p l e j u n c t i o n s and a l o n g e l o n g a t e g r a i n b o u n d a r i e s c o i n c i d e n t w i t h p a r t i a l l y a n n e a l e d k i n k band b o u n d a r i e s . T h e i r presence appears t o be r e l a t e d t o a l a t e a n n e a l i n g / t h e r m a l e v e n t . 2.10 PARAGENESIS R e l i c t d e p o s i t i o n a l r e l a t i o n s p r e s e r v e d i n sheared samples and p r i m a r y t e x t u r e s i n unsheared samples p e r m i t a p a r a g e n e s i s t o be d e t e r m i n e d , i n c o n t r a s t t o the concerns of bo t h Uglow (1917) and Bateman (1925). The p a r a g e n e t i c F i g u r e 2-8. R e f l e c t e d p l a n e p o l a r i z e d l i g h t photomicrographs of p o l i s h e d and e t c h e d samples. A: Growth-annealing twins i n s p h a l e r i t e p o r p h y r o c 1 a s t s ( e t c h e d by KMnOa + H i S O O . B: Kink bands d e f i n e d by e t c h p i t s ( B r e b r i c k and Scanlon e t c h a n t ) . C: Sutured b o u n d a r i e s between e l o n g a t e g a l e n a g r a i n s ( e t c h a n t as i n B). D: S p h a l e r i t e ( c e n t e r ) i n groundmass of annealed g a l e n a . F r e i e s 1 e b e n i t e o c c u p i e s i n t e r s t i a l p o s i t i o n s to foam t e x t u r e . R e l i c t s u b g r a i n e v i d e n t i n upper l e f t ( b o t h B r e b r i c k and S c a n l o n e t c h a n t and KMnO. + H ; S O « ) . 5 5 56 sequence of ore d e p o s i t i o n f o r Hallmac f o l l o w s c l o s e l y t h a t e s t a b l i s h e d by C a i r n e s (1934) f o r the S l o c a n camp, 'commencing w i t h the e a r l i e s t m i n e r a l : q u a r t z , p y r i t e , c a l c i t e , s i d e r i t e , s p h a l e r i t e , grey copper, g a l e n a and a r g e n t i t e , p y r a r g y r i t e , s i l v e r . ' The t e x t u r a l and p a r a g e n e t i c r e l a t i o n s h i p s f o r ore and gangue m i n e r a l s i s summarized i n a l i n e diagram ( F i g . 2-9) and a Van de Veer diagram ( F i g . 2-10). Shear and f r a c t u r i n g of not l e s s than two s e p a r a t e e v e n t s , l i k e l y s y n - and p o s t - o r e d e p o s i t i o n has a l t e r e d the e a r l i e s t formed t e x t u r a l r e l a t i o n s . Uglow (1917) r e c o g n i z e d ' g n e i s s i c g a l e n a ' from S l o c a n o r e s t o be a s h e a r - g e n e r a t e d t e x t u r e and suggested the en e c h e l o n d i s t r i b u t i o n of ore b o d i e s ( w i t h i n a shear zone) was r e l a t e d t o s h e a r i n g p a r a l l e l t o an e a r l y v e i n . Ore shoot d i s t r i b u t i o n , geometry and m i n e r a l m i c r o s t r u c t u r e s suggest a R i e d e l (1929) shear f r a c t u r e o r i g i n w i t h i n the Hallmac d e p o s i t . More r e c e n t s t u d i e s ( A t k i n s o n , 1976; C l a r k et al. , 1977; McClay and A t k i n s o n , 1977) of the d e f o r m a t i o n and a n n e a l i n g p r o p e r t i e s f o r s i n g l e g a l e n a c r y s t a l s and p o l y c r y s t a l l i n e a g g r e g a t e s have l e d t o the q u a n t i f i c a t i o n of d e f o r m a t i o n mechanisms and r e c o v e r y p r o c e s s e s . I n t e r p r e t a t i o n of m i c r o s t r u c t u r e s i n l i g h t of t h e s e e x p e r i m e n t a l s t u d i e s a l l o w s c o n s t r a i n t s t o be p l a c e d on t i m i n g and mechanism of the r e d i s t r i b u t i o n of ore m i n e r a l s . Dynamic r e c r y s t a l l i z a t i o n ( s u t u r e d b o u n d a r i e s on e l o n g a t e g r a i n s , F i g . 2-8c) and p o l y g o n i z a t i o n ( F i g . 2-8d) GANGUE MINERALS Q U A R T Z _ SIDERITE C A L C I T E HYPOGENE MINERALS PYRITE S P H A L E R I T E G O L D C H A L C O P Y R I T E T E T R A H EDRITE G A L E N A FREIBERGITE FREIESLEBENITE A N D O R I T E M I A R G Y R I T E P Y R A R G Y R I T E A C A N T H I T E SUPERGENE MINERALS G O E T H I T E — after pyrite, chalcopyrite, siderite LEPIDOCROCITE — after pyrite, siderite C O V E L L I T E — after chalcopyrite, tetrahedrite, sphalerite, freibergite P Y R O L U S I T E / P S I L O M E L A N E — after rhodochrosite, manganosiderite A N G L E S I T E — rhythmic replacement of galena along cracks CERUSSITE -— less common than anglesite, replaces galena F i g u r e 2-9. P a r a g e n e s i s Hallmac Mine L i n e Diagram. 58 goethite pyrolusite chalcopyrite goethite lepidocrocite tetrahedrite pyrrhotite chalcopyrite chalcopyrite-^— covell ite chalcopyrite covellite ceruss i te anglesite F i g u r e 2-10. Van de Veer P a r a g e n e t i c diagram Hallmac d e p o s i t . 59 a r e common throughout deformed samples. Both a r e g e n e r a t e d by i n t r a c r y s t a l l i n e d e f o r m a t i o n (McClay, 1984). An upper t e m p e r a t u r e l i m i t of 300°C ( d r y e x p e r i m e n t a l d e f o r m a t i o n ) i s i n v o k e d by C l a r k and o t h e r s (1977), as c h a r a c t e r i s t i c of ' s u t u r e d ' k i n k band b o u n d a r i e s . Much lower t e m p e r a t u r e s a r e i n f e r r e d f o r a f l u i d - d o m i n a t e d system such as e n v i s i o n e d d u r i n g the v e i n d e p o s i t i o n e p i s o d e . G r o w t h - a n n e a l i n g t w i n s i n s p h a l e r i t e , l o c a l l y p i n n e d g r a i n b o u n d a r i e s ( c a l c i t e ) , and foam t e x t u r e (120° t r i p l e j u n c t i o n s ) i n the most sheared samples are a l l i n d i c a t i o n s of a n n e a l i n g p r o c e s s e s . No r e s t r i c t i o n or s y s t e m a t i c d i s t r i b u t i o n between a n n e a l i n g t e x t u r e s v s . d e f o r m a t i o n t e x t u r e s i s o b v i o u s . F o r m a t i o n of a n n e a l e d t e x t u r e s c o i n c i d e w i t h a p e r i o d of h i g h ambient te m p e r a t u r e e i t h e r ; metamorphic or h y d r o t h e r m a l . R e c r y s t a l l i z a t i o n and m i c r o s c o p i c r e d i s t r i b u t i o n of ore m i n e r a l s o c c u r r e d w i t h i n the l o d e i n response t o t e c t o n i s m . A s i m p l i s t i c approach t o u n d e r s t a n d i n g the d i s t r i b u t i o n of A g - b e a r i n g e x s o l u t i o n b o d i e s i n deformed samples was a c h i e v e d by a n a l y z i n g s m a l l a r e a s of the sample i n terms of s i n g l e c r y s t a l d e f o r m a t i o n mechanisms. A l t h o u g h the p o l y c r y s t a l l i n e / p o l y m i n e r a l i c n a t u r e of the ore r e s u l t s i n s u b s t a n t i a l l y more complex b e h a v i o u r d u r i n g d e f o r m a t i o n , t h i s p r o v i d e s a w o r k i n g model f o r i n t r a g r a i n changes d u r i n g deformat i o n . N u c l e a t i o n of e x s o l u t i o n phases are l o c a l i z e d a t i m p e r f e c t i o n s such as d i s l o c a t i o n s , t w i n l a m e l l a e , s l i p 60 p l a n e s and g r a i n b o u n d a r i e s . Galena has two p r i n c i p a l s l i p systems {100} <011> and {110} <110>, the former - o p e r a t i v e below 300°C and a l o n g which d i s l o c a t i o n c r e e p and g l i d e a r e the d e f o r m a t i o n mechanisms (McClay, 1980). At low temperature d e f o r m a t i o n t h e r e f o r e the s l i p and e x s o l u t i o n p l a n e s a r e c o i n c i d e n t f o r g a l e n a . A d i s l o c a t i o n c l i m b - t y p e mechanism i s e n v i s i o n e d ( t h i s s t u d y ) t o f a c i l i t a t e m i g r a t i o n from t h i s p l a n e of h i g h s t r e s s t o s u b g r a i n boundary l o c a t i o n s . These i n c l u s i o n s a l t e r n a t i v e l y may r e p r e s e n t p r i m a r y e x s o l u t i o n s i n v o l v i n g no a d d i t i o n a l d e p o s i t i o n . Secondary or ' d e f o r m a t i o n i n d u c e d ' e x s o l u t i o n i n i t i a t e d by shear s t r e s s , l i k e l y o c c u r r e d d u r i n g dynamic r e c r y s t a l l i z a t i o n / p o l y g o n i z a t i o n . G r a i n boundary m i g r a t i o n r e s u l t e d w i t h c r y s t a l l i z a t i o n of f r e i e s l e b e n i t e i n t e r s t i a l t o g a l e n a s u b g r a i n s . E x s o l u t i o n m i n e r a l s a r e i m p u r i t i e s and as such a l l o w d e f o r m a t i o n t o t a k e p l a c e a t lower t e m p e r a t u r e s and/or lower s t r e s s . H a l l and Czamanske (1975) r e p o r t e d s i m i l i a r m o b i l i z a t i o n and r e c r y s t a l l i z a t i o n of i n c l u s i o n s f o l l o w i n g g l i d i n g and a n n e a l i n g i n l e a d - s i l v e r o r e s from Idaho. The f i n e - g r a i n e d n a t u r e (average 25 u) of secondary e x s o l u t i o n s i l v e r m i n e r a l s and t h e i r p r e f e r e n t i a l l o c a l l i z a t i o n a l o n g g a l e n a g r a i n b o u n d a r i e s a r e i m p o r t a n t i n c o n s i d e r a t i o n s i n v o l v i n g o re t r e a t m e n t , i n p a r t i c u l a r e x t r a c t i o n . L a t e groundwater c i r c u l a t i o n a l o n g the lo d e s t r u c t u r e s has o x i d i z e d , l e a c h e d and f u r t h e r o b l i t e r a t e d p r i m a r y s t r u c t u r e s w i t h the p r o d u c t i o n of supergene o v e r p r i n t i n g . 61 2.11 METAL DISTRIBUTION « 2.11.1 ASSAY DATA Data used t o examine m e t a l d i s t r i b u t i o n p a t t e r n s were c o l l e c t e d and s u p p l i e d t o the w r i t e r by G. S a l a z a r . The d a t a c o m p r i s e s 150 c h i p samples d i s t r i b u t e d r o u g h l y e q u a l l y between f o o t w a l l and h a n g i n g w a l l v e i n s . Samples were a n a l y s e d by atomic a b s o r p t i o n s p e c t r o p h o t o m e t r y a t L o r i n g L a b o r a t o r i e s L t d . , C a l g a r y , A l b e r t a . The assay d a t a i n c l u d e Ag, Pb, Zn, Cu, Au v a l u e s and c o r r e s p o n d i n g w i d t h measurements. I n i t i a l d a t a were s u b d i v i d e d i n t o 1) h a n g i n g w a l l v e i n (n = 6 1 ) , 2) f o o t w a l l v e i n (n = 73) and 3) w a l l r o c k of both v e i n s t r u c t u r e s (n = 2 6 ) , a l l d a t a a r e i n Appendix A. Assay r e s u l t s a r e i n c o m p l e t e f o r Au and Cu. Sample c o o r d i n a t e s were d e t e r m i n e d f o r each sample t o p e r m i t machine c o n t o u r i n g i n p l a n and v e r t i c a l s e c t i o n . Where more than one sample r e p r e s e n t s a s i n g l e p o i n t on the v e i n the d a t a were averaged (the d i s p a r i t y between samples i s l a r g e i n some c a s e s ) . T h i s reduced the d a t a s e t t o n = 43 and n = 30 f o r f o o t w a l l and h a n g i n g w a l l samples r e s p e c t i v e l y . 2.11.2 STATISTICAL ANALYSIS His t o g r a m s and p r o b a b i l i t y p l o t s of both a r i t h m e t i c and l o g 1 0 v a l u e s f o r a l l v a r i a b l e s were computer g e n e r a t e d . Ag, Pb and Au c o n s i s t of m i x t u r e s of 3, 2 and 1 l o g n o r m a l d i s t r i b u t i o n s r e s p e c t i v e l y . Zn and Cu, 3 and 1 normal d i s t r i b u t i o n s r e s p e c t i v e l y . Width was c o n s i d e r e d t o o 62 Table 2-2 Means, standard deviations and thresholds determined graphically for p a r t i t i o n e d metal values.  Footwal1 Vein Element Populations un 1 ts % b' b+s Ag A( .59) 60 1 10 o/t B( .33) 12 22 C( .08) 3 4. Pb % Zn Cu" A(.80) 9.8 30 B(.20) .62 1.3 A(.03) B(.15) 2 . 37 1 .72 2.42 1 .95 1 . 3 C(.82) 0.92 A(1.0) 0.175 0.33 Thresho1ds S3 • 32 45 25 .8 5. '. 1 -.8 3 J o.; |. 3 . 32 2 . . 47 1. 1 .: .52 .04 o.. Hanntnnwall V a i n Populations % A(.30) 82 b+s-4 1 10 Threshold b- S3 46 46 17 B( .50) 15 25 8.8 6.0 C( .20) 1.8 3. 1 1 . 1 A( .42) 21 36 12 20 7 .0 B( .58) 1 . 8 5.8 0.54 A( .05) 2.6 2.7 2 . 5 2 . 37 B( .57) 1 .4 1 .8 0.97 1 .05 0.5 C( . 38) 0.55 0. 78 0.30 A( .08) 0. 35 0.39 0.31 0. 28 B( .52) 0.15 0.21 0.09 0. 10 0.03 C( .40) 0.08 0.07 0.02 Au o/t A(1.0) 0.0057 0.022 0.0014 0.08 A(1.0) 0.0076 0.026 0.0023 0.08 % of data 1n population 1 ant 1 log of mean of lognormal population 2 ant 11og of mean plus one standard deviation df lognormal population •3 a n t l l o g of mean minus one standard deviation of lognormal population 4 normal d i s t r i b u t i o n 63 Cumulative Percent F i g u r e 2-11. P r o b a b i l i t y graph f o r 61 Ag values from hangingwall v e i n . Black dots are o r i g i n a l data, open c i r c l e s are estimated p a r t i t i o n i n g p o i n t s . Three p o p u l a t i o n s are evident from l o g normal d i s t r i b u t i o n of Ag v a l u e s . 64 s u b j e c t i v e , w i t h r e g a r d s t o the n a t u r e of the s e v e i n s and i s not c o n s i d e r e d f u r t h e r . P a r t i t i o n i n g the d a t a i n t o the r e s p e c t i v e p o p u l a t i o n s d e s c r i b e d above was a c h i e v e d g r a p h i c a l l y , f o l l o w i n g the pr o c e d u r e o u t l i n e d by S i n c l a i r (1976). F i g u r e 2-11 i l l u s t r a t e s the p r o b a b i l i t y p l o t f o r Ag from the h a n g i n g w a l l . Three p o p u l a t i o n s a r e e v i d e n t . The upper two w i t h t h r e s h o l d v a l u e s of 6 and 46 oz Ag/ton, c o r r e s p o n d t o ' m i l l - g r a d e ' and 'high-grade' ore r e s p e c t i v e l y . The means, s t a n d a r d d e v i a t i o n s and t h r e s h o l d v a l u e 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 of Ag, Pb, Zn, Cu and Au a r e p r e s e n t e d i n Ta b l e 2-2. The t h r e s h o l d v a l u e s p r o v i d e the co n t o u r v a l u e s which s e p a r a t e and d e f i n e h i g h - g r a d e ore shoots ( e q u a l p o p u l a t i o n A) and s e p a r a t e m i n e r a l z o n a t i o n p a t t e r n s . 2.11.3 TRIANGULAR PLOTS G o l d s m i t h (1984) has shown the u s e f u l n e s s of t r i a n g u l a r p l o t s i n c h a r a c t e r i z i n g m e t a l r a t i o s f o r d e p o s i t s i n i n d i v i d u a l m i n i n g camps. In t h i s s tudy p l o t t i n g a s s a y d a t a on t r i a n g u l a r p l o t s p e r m i t s r e c o g n i t i o n of s e p a r a t e d a t a c l u s t e r s w i t h i n a s i n g l e d e p o s i t . The most u s e f u l t r i a n g u l a r p l o t s f o r examining fundamental d i f f e r e n c e s i n m e t a l r a t i o s i n Hallmac assay d a t a a r e Ag-Zn-Pb and Cu-Ag-Pb p l o t s . To produce d i s t r i b u t i o n p a t t e r n s more c o n d u c i v e t o i n t e r p r e t a t i o n Cu and Au d a t a were c o n v e r t e d t o ppm/100. S i l v e r remained as o z / t o n and Pb and Zn as p e r c e n t . 65 A g o z / t o n F i g u r e 2-12. Ag-Zn-Pb T r i a n g u l a r p l o t s of f o o t w a l l , hangingwall and wal l r o c k , Hallmac Mine.. 66 S i l v e r ( o z ) - z i n c ( % ) - l e a d ( % ) p l o t s f o r f o o t w a l l and h a n g i n g w a l l d a t a s e t s ( F i g . 2-12) i n d i c a t e t h a t 1) Ag-Pb r a t i o s f o r v e i n s (and w a l l r o c k ) g e n e r a l l y exceed 1 o z / % , 2) z i n c i s s u b o r d i n a t e t o l e a d (as f o r Trout Lake camp, G o l d s m i t h , 1984) and 3) a subset of the f o o t w a l l d a t a c o n t a i n s h i g h Ag-Pb r a t i o s . C o m p a r i s i o n of F i g u r e 2-12a w i t h F i g u r e 2-13b i n d i c a t e s a subgroup of 27 samples w i t h Ag-Pb r a t i o s e x c e e d i n g 80/20 = 4 oz Ag/1% Pb. E x a m i n a t i o n of a n a l y s e s from s u b d r i f t 1715 West ( F i g . 2-12a) shows t h a t 25 of the t o t a l 29 o r i g i n a t e from t h i s one s m a l l a r e a . Once s u b d r i f t 1715 West i s i s o l a t e d , d i s t i n c t i o n between h a n g i n g w a l l and f o o t w a l l become l e s s e v i d e n t . F i g u r e 2-12c, a p l o t of m e t a l r a t i o s i n w a l l r o c k shows 1) c o n s i d e r a b l e s c a t t e r , 2) a c o n t i n u o u s v a r i a t i o n i n p r o p o r t i o n s e x t e n d i n g from the m i n e r a l i z e d v e i n f i e l d t o the z i n c v e r t e x , and 3) Pb t o be g e n e r a l l y s u b o r d i n a t e t o Zn. A s m a l l group of w a l l r o c k samples (n = 5) c o n t a i n s i m i l i a r p r o p o r t i o n s but lower a b s o l u t e amounts of Ag-Zn-Pb than average v e i n samples. T h i s apparent o v e r l a p emphasizes the d i f f i c u l t y " i n s e p a r a t i n g v e i n from w a l l r o c k , p a r t i c u l a r l y where p o s t - o r e d e f o r m a t i o n has o b s c u r r e d the c o n t a c t s . No apparent supergene enrichment of s i l v e r v a l u e s i s e v i d e n t f o r w a l l r o c k from s u b d r i f t 1715 West. F i g u r e 2-13a, the c o p p e r ( p p m / 1 0 0 ) - z i n c ( % ) - l e a d ( % ) p l o t shows 1) a c l u s t e r of d a t a where Pb v a l u e s a r e s u b o r d i n a t e t o z i n c (a c h a r a c t e r i s t i c t y p i c a l of w a l l r o c k s ) , and 2) a c l u s t e r near the copper v e r t e x c o r r e s p o n d i n g t o a f o o t w a l l F i g u r e 2-13. Ag-Cu-Pb and Zn-Cu-Pb T r i a n g u l a r p l o t s of f o o t w a l l , Hallmac Mine. 68 subset r e p r e s e n t i n g s u b d r i f t 1715 West. H a n g i n g w a l l Cu-Zn-Pb p l o t show a s i m i l i a r c l u s t e r of d a t a which c o r r e s p o n d s t o sample s i t e s l o c a t e d i n the lo w e s t p o r t i o n s of the h a n g i n g w a l l w o r k i n g s . T h i s a r e a c o i n c i d e s r o u g h l y i n e l e v a t i o n w i t h s u b d r i f t 1715 West. F i g u r e 2-13b, the s i l v e r ( o z ) - c o p p e r ( p p m / 1 0 0 ) - l e a d ( % ) p l o t does not produce a c l e a r l y d e f i n e d f o o t w a l l s u b s e t . I n s t e a d , the d a t a tends t o spre a d out c l o s e t o the Ag-Cu l i n e i n . r e s p o n s e t o the low r e l a t i v e Pb abundance of t h e d a t a . 2.11.4 PLAN AND VERTICAL CONTOURING Composite p l a n s , r a t h e r than i n d i v i d u a l l e v e l p l a n s , have been c o n s t r u c t e d f o r Ag, Pb, Zn, Cu and Au u t i l i z i n g the e n t i r e assay d a t a base. For t h i s , d a t a from a l l l e v e l s and both s t r u c t u r e s ( h a n g i n g w a l l , f o o t w a l l , and w a l l r o c k ; n = 150) were p r o j e c t e d t o one p l a n e and c o n t o u r e d . T h r e s h o l d v a l u e s as d e f i n e d i n T a b l e 2-2 were used as the i n i t i a l c o n t o u r v a l u e s . The more common p r a c t i c e of c o m p i l i n g l e v e l p l a n s proved u n s a t i s f a c t o r y because of s m a l l d a t a s e t s r e f l e c t i n g t he l i m i t e d s i z e of w o r k i n g s . Composite p l a n s f o r Ag and Pb (not repro d u c e d here) i l l u s t r a t e the g e n e r a l e a s t - w e s t s t r i k e of the f i s s u r e and the g r o s s geometry of assay d e f i n e d o re s h o o t s , the s o u t h w e s t e r l y p i t c h of whi c h i s the most apparent f e a t u r e . S i m p l e c o r r e l a t i o n between elements and z o n a t i o n p a t t e r n s a r e b e s t 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 . U s i n g 1716 -x2.00 T .00 5 7 2 5 . 0 5 7 4 1 . 0 5 7 5 7 . 0 D i s t a n c e (m) F i g u r e 2-14. Ha n g i n g w a l l v e r t i c a l s e c t i o n . Dashed con t o u r l i n e s a r e l o g ( l 0 0 x Z n % ) ; d o t t e d l i n e s l o g Ag oz/ton ; and s o l i d l i n e s l o g ( l O x P b % ) . Z i n c o u t l i n e s a c o n c e n t r i c c e n t r a l zone c o r e d by h i g h grade Ag and Pb. Ag and Pb show c o i n c i d e n t d i s t r i b u t i o n and d e f i n e ore shoot l o c a t i o n s throughout the w o r k i n g s . 70 assay d a t a from e i t h e r f o o t w a l l or h a n g i n g w a l l s t r u c t u r e s , e a s t - w e s t v e r t i c a l s e c t i o n s f o r both were c o n s t r u c t e d . The v a r i a b l e s i n c l u d e d the same f i v e m e t a l s l i s t e d above and, i n a d d i t i o n , v a r i o u s metal r a t i o s . F i g u r e 2-14 shows c o n t o u r e d l o g Ag v a l u e s f o r the h a n g i n g w a l l w o r k i n g s . O v e r l a y i n g l o g Pb ( p o p u l a t i o n A) and l o g (100 x Zn) ( p o p u l a t i o n s A & B) c o n t o u r s , a z o n a t i o n p a t t e r n becomes e v i d e n t . Namely, t h e r e i s a mutual d i s t r i b u t i o n of h i g h Ag and Pb, c h a r a c t e r i z e d by a p o s i t i v e c o r r e l a t i o n , z i n c i s p e r i p h e r a l t o b o t h Ag and Pb and o u t l i n e s a c o n c e n t r i c zone of h i g h v a l u e s c e n t e r e d on the h a n g i n g w a l l w o r k i n g s . The same p a t t e r n f o r Ag and Pb, though l e s s apparent f o r z i n c , i s found i n the f o o t w a l l v e r t i c a l s e c t i o n . S u b d r i f t 1715 West d a t a ( s e p a r a b l e on the b a s i s of t r i a n g u l a r p l o t s ) was i s o l a t e d from the f o o t w a l l and .contoured s e p a r a t e l y ( F i g . 2-15). P l o t t i n g s i n g l e m e t a l s show t h a t h i g h e s t Ag and Pb v a l u e s c o i n c i d e w i t h the uppermost s e c t i o n s of both r a i s e s and the west end of the s u b d r i f t . C o n t o u r i n g Ag s u g g e s t s two >50 o z / t o n Ag zones p i t c h i n g 30° SE. Pb v a l u e s d e c r e a s e down p i t c h away from the 'A g - d e f i n e d ' s h o o t s . Contour p a t t e r n s f o r both Zn and Cu a r e l e s s c o n s i s t e n t , showing no s y s t e m a t i c d i s t r i b u t i o n . H i g h v a l u e s f o r both m e t a l s c o i n c i d e i n p a r t w i t h the ore s h o o t s , but j u s t as commonly do n o t . Contour p l o t s of l o g Pb-Zn r a t i o s show t h a t v a l u e s d e c r e a s e down p i t c h , away from the ore s h o o t s . The r e v e r s e i s t r u e f o r l o g Ag-Pb r a t i o s , v a l u e s of which i n c r e a s e by an 1 1 I I 5 7 4 0 E 5 7 4 5 E , s > 5 7 5 5 E 17 2 5m \ 17 20m <o \ \ \ A fir A \ ^ / X 17 15m / J/l ' ^ . \o A . 1 I I I 5 7 4 0 E 5 7 4 5 E 5 7 5 0 E 5 7 5 5 E L ° 9 l ° P b ^ ^ ^ ' ^ y f ( A ^ 1 . 5 0 ^^zzz^:—^S-^ _ , i . o o B. L o g ( A g / P b ) , 0 ° V ^ l . 2 5 _ 1720m ^ / a . s . l . A A— ' \ ^ 1 2 5 , 1.00 ) / 1 7 1 5 m \ * jy/~ ^ 1- 75 5 7 4 0 E 5 7 4 5 E 5 7 5 0 E 5 7 5 5 E 1 1 J 1 D. o o IV* L o g ( A g / Z n ) \AJ A A A A \ 5 7 4 0 E 5 7 4 5 E ' 5 7 5 0 E 5 7 5 5 E 1 i 1 1 F i g u r e 2-15. Contoured assay v a l u e s f o r s u b d r i f t 1715 W. T r i a n g l e s g i v e d a t a p o i n t s . A: Ag i n o z / t o n . B: Log(10xPb) i n p e r c e n t . C: Log Ag/Pb r a t i o s Ag i n o z / t o n and Pb 1n p e r c e n t . D: Log Ag/Zn r a t i o w i th Ag i n oz / t o n and Zn i n p e r c e n t . 72 o r d e r of magnitude p r o c e e d i n g from the upper t o lower p o r t i o n s of the wo r k i n g s ( F i g . 2 - 1 5 C ) . Log Ag-Zn r a t i o s ( F i g . 2-l5d) d e f i n e a w e s t e r l y p i t c h i n g c e n t r a l low p e r p e n d i c u l a r t o the p i t c h of the ore s h o o t s . Thus d e f i n i n g l i m i t s t o the down p i t c h e x t e n s i o n of the >50 o z / t o n Ag ore s h o o t s . 2.12 DISCUSSION M e t a l z o n a t i o n p a t t e r n s i n i n d i v i d u a l o re s h o o t s , noted f i r s t by C a i r n e s (1934) have been the f o c u s of r e i n t e r p r e t a t i o n by numerous l a t e r s t u d i e s (Robinson, 1948; Hed l e y , 1952; O r r , 1972). The z o n a t i o n p a t t e r n i s d e s c r i b e d as a v e r t i c a l phenomenon c h a r a c t e r i z e d by g a l e n a r i c h i n s i l v e r m i n e r a l s o c c u p y i n g the upper-most s e c t i o n s . S u r r o u n d i n g t h i s i s a s p h a l e r i t e - r i c h zone which g i v e s way s u c c e s s i v e l y downwards t o p y r i t i c and s i l i c i c zones. C a i r n e s (1934) a t t r i b u t e d t h i s p a t t e r n t o a s t e e p geothermal g r a d i e n t c o i n c i d e n t w i t h the p r e s e n t topography. Hedley (1952) and Robinson (1948) s u g g e s t e d m i n e r a l p e r c i p i t a t i o n t o be a p r e s s u r e r e l a t e d phenomena, r e l a t i n g z o n a t i o n t o v e i n d i l a t i o n which i n t u r n was r e l a t e d t o c l o s e n e s s t o the s u r f a c e . Orr (1971) u s i n g p r o d u c t i o n d a t a and e l e v a t i o n of S l o c a n C i t y d e p o s i t s ( a d j a c e n t t o the south) c o u l d not i d e n t i f y v e r t i c a l z o n i n g w i t h i n i n d i v i d u a l d e p o s i t s , a l t h o u g h he documented a d i s t r i c t z o n a t i o n f o r the S l o c a n C i t y camp. 73 T r a d i t i o n a l l y the camp z o n a t i o n p a t t e r n has been viewed as u n i d i r e c t i o n a l and not c o n c e n t r i c . From t o p t o bottom the p a t t e r n i s i d e n t i c a l t o the p a r a g e n e t i c sequence f o r the camp and e a r l y workers c i t e d t h i s t o support a g r a n i t i c s o u r c e f o r the d e p o s i t s . I d e a l l y , m i n e r a l d e p o s i t i o n i n a d i l a t i o n s t r u c t u r e s h o u l d produce a c o n c e n t r i c z o n a t i o n p a t t e r n which r e f l e c t s the p a r a g e n e s i s w i t h the e a r l i e s t m i n e r a l s a d j a c e n t t o v e i n w a l l s and the l a t e s t the c e n t r e or c o r e . M i s s i n g zones would r e f l e c t i n t e r m i t t e n t c l o s u r e of the s t r u c t u r e t h a t r e s t r i c t e d f l u i d f l o w . M e t a l z o n a t i o n i n the Hallmac d e p o s i t r e f l e c t a t y p i c a l 'wet' ore p a r a g e n e s i s . The d i s t r i b u t i o n of 'dry' s i l v e r m i n e r a l i z a t i o n ( s u b d r i f t 1715 West) su g g e s t s t h i s a r e a of the lod e was open t o l a t e - s t a g e m i n e r a l i z i n g f l u i d s . T r i a n g u l a r p l o t s have been shown t o be e f f e c t i v e on a s i n g l e d e p o s i t s c a l e i n d e f i n i n g s e p a r a t e groups of d a t a . Such p l o t s u t i l i z e p r o p o r t i o n s r a t h e r than a b s o l u t e amounts of t h r e e e l e m e n t s . Thus, where s t r o n g c o r r e l a t i o n e x i s t s between the elements l i t t l e or no d i s t i n c t i o n i s made between h i g h grade or low grade samples. D i s c r i m i n a t i o n between 'wet' ore and 'dry' ore and between s l i g h t l y m i n e r a l i z e d w a l l r o c k and low-grade v e i n m a t e r i a l , i s p o s s i b l e on the b a s i s of r e l a t i v e p r o p o r t i o n s of a n a l y t i c a l d a t a , p a r t i c u l a r l y Ag, Pb and Zn. U s i n g e i t h e r r e l a t i v e p r o p o r t i o n s (of these t h r e e m e t a l s ) or s e l e c t i v e m e t a l r a t i o s , ' d i s c r i m i n a n t a r e a s ' c o u l d be d e f i n e d f o r t r i a n g u l a r p l o t s . These a r e a s would c o r r e s p o n d t o s p e c i f i c zones w i t h i n 74 the i d e a l z o n a t i o n p a t t e r n f o r S l o c a n ore s h o o t s and p r o v i d e a more p r e d i c t i v e a l t e r n a t i v e f o r ' l o c a t i n g ore s h o o t s . H i s t o r i c a l l y Ag v a l u e s a l o n e have d i r e c t e d underground e x p l o r a t i o n . C o n t o u r i n g assay d a t a , ( F i g . 2-14) a l l o w s r e c o g n i t i o n of g e n e r a l i z e d m e t a l a s s o c i a t i o n s and s p a t i a l d i s t r i b u t i o n s w i t h i n the Hallmac d e p o s i t . A n a l y s i s of Hallmac m e t a l d i s t r i b u t i o n p a t t e r n s f o l l o w i n g S i n c l a i r and T e s s a r i ' s method (1980), i n d i c a t e s a g e n e r a l i z e d z o n a t i o n p a t t e r n c o m p a t i b l e w i t h the e s t a b l i s h e d p a r a g e n e s i s . The method i n v o l v e s a r r a n g i n g samples i n o r d e r of d e c r e a s i n g v a l u e s of a key m e t a l , i n t h i s s t u d y b o t h Ag and Zn were t e s t e d . Other element d i s t r i b u t i o n s a r e examined r e l a t i v e t o t h i s i d e a l l i z e d o r d e r i n g of one element. Upper p o p u l a t i o n (A) v a l u e s c o r r e s p o n d i n g t o h i g h - g r a d e ore shoots r e f l e c t a s i m p l e z o n a t i o n model of h i g h Zn v a l u e s p e r i p h e r a l t o or e n v e l o p i n g a h i g h Ag and Pb c o r e . T h i s z o n a l p a t t e r n does not extend beyond the s c a l e of an ore shoot f o r e i t h e r f o o t w a l l or h a n g i n g w a l l d a t a . Contoured r a t i o s of m e t a l p a i r s f o r both h a n g i n g w a l l and f o o t w a l l s t r u c t u r e s , ( F i g . 2-15) shows a d i s t i n c t i v e z o n a t i o n p a t t e r n f o r s u b d r i f t 1715 West. T h i s d e p a r t u r e from the g e n e r a l l i z e d 'wet-ore' z o n a t i o n p a t t e r n s u g g e s t s e i t h e r a s e p a r a t e Ag m i n e r a l i z i n g event of enrichment or nonsymmetric o v e r l a p of z o n a t i o n p a t t e r n s . C o n t o u r i n g the d a t a i n d i c a t e s t h a t h i g h r a t i o s i n which l o g (Ag/Pb) exceeds 1 a r e l o c a l i z e d a t the f r i n g e s of ore s h o o t s , whereas 75 average r a t i o s a r e 1. Comparing a b s o l u t e v a l u e s of Ag and Pb i n d i c a t e s o n l y lower average Pb r a t h e r than h i g h e r Ag f o r s u b d r i f t 1715 West. Ag v a l u e s e x t e n d outward from t h i s Ag-Pb c o r e , l i k e l y i n the form of l a t e s tage A g - b e a r i n g m i n e r a l s . The lower than average abundance of g a l e n a i s e v i d e n t i n p o l i s h e d s e c t i o n s from 1715 West s u b d r i f t , where h a l f of the samples c o n t a i n e d few v i s i b l e s u l p h i d e s of any t y p e . P y r a r g y r i t e and a c a n t h i t e have r e p l a c e d both g a l e n a and l o c a l l y c a l c i t e , s u g g e s t i n g a l a t e s t a g e of p r e d o m i n e n t l y s i l v e r m i n e r a l i z a t i o n . An e q u a l l y p l a u s i b l e e x p l a n a t i o n f o r apparent enrichment of Ag and Cu w i t h r e s p e c t t o Pb i s supergene e n r i c h m e n t . 2.13 CONCLUSIONS Hallmac d e p o s i t c o n t a i n s the m i n e r a l o g y t y p i c a l of C a i r n e s ' 'wet-ore' c l a s s i f i c a t i o n . M i n e r a l o g i c a l and p a r a g e n e t i c s t u d i e s have e s t a b l i s h e d the pr e s e n c e of p y r i t e - s p h a l e r i t e - g a l e n a and a complex assemblage of s i l v e r m i n e r a l s . E a r l y and l a t e s t a g e s of s i l v e r m i n e r a l i z a t i o n a r e c h a r a c t e r i z e d by d i s t i n c t i v e m i n e r a l o g i e s and a r e s e p a r a b l e by t h e i r r e s p e c t i v e m e t a l z o n a t i o n p a t t e r n s . Observed t e x t u r e s and d i s t r i b u t i o n p a t t e r n s of e a r l y f r e i b e r g i t e and A g - s u l p h o s a l t s i n d i c a t e an e x s o l u t i o n o r i g i n i n g a l e n a . L a t e s t a g e s i l v e r m i n e r a l s , p y r a r g y r i t e , a n d o r i t e and a c a n t h i t e , p o s t d a t e the b u l k of g a l e n a d e p o s i t i o n ; t h u s , replacement of g a l e n a and o v e r p r i n t i n g of e a r l i e r d e v e l o p e d z o n a t i o n p a t t e r n s t y p i f y t h i s younger s t a g e of s i l v e r m i n e r a l i z a t i o n . 76 E a r l y stage A g - s u l p h o s a l t t e x t u r e s i n d i c a t e e x s o l u t i o n f o l l o w i n g an i n i t i a l p r e c i p i t a t i o n as some PbS-Ag 2S-Sb 2S 3 s o l i d s o l u t i o n . E x s o l u t i o n l a t h s of f r e i e s l e b e n i t e i n g a l e n a s u g g e s t s a temperature of d e p o s i t i o n of above 350°C (Hoda et al: , 1975) . S u l p h i d e m i c r o s t r u c t u r e s w i t h i n the l o d e i n d i c a t e r e d i s t r i b u t i o n of m i n e r a l s on b o t h a macro and m i c r o s c o p i c scale., r e l a t e d t o d u c t i l e d e f o r m a t i o n and a n n e a l i n g p r o c e s s e s . E x s o l u t i o n m i n e r a l s i n g a l e n a a r e most a f f e c t e d . S t a t i s t i c a l l y d e f i n e d c o n t o u r v a l u e s ( t h r e s h o l d s ) c l e a r l y i d e n t i f y a z o n a l d i s t r i b u t i o n of s u l p h i d e s i n o r e s h o o t s . These p a t t e r n s i l l u s t r a t e the ' c l a s s i c camp' z o n a t i o n , d e v e l o p e d f o r s i n g l e ore s h o o t s . R a t i o s of m e t a l p a i r s i s o l a t e s u b d r i f t 1715 West as d i f f e r e n t from the g e n e r a l i z e d z o n a l p a t t e r n . T r i a n g u l a r p l o t s of m e t a l abundances a r e a l s o e f f e c t i v e i n d i s t i n g u i s h i n g v e i n m a t e r i a l i n s u b d r i f t 1715 West d a t a as d i f f e r e n t from the r e s t of Hallmac d e p o s i t . The 1715 West d a t a c l u s t e r c l o s e t o the Ag v e r t e x on Ag-Zn-Pb p l o t i n d i c a t i n g r e l a t i v e l y h i g h e r Ag and lower Pb than the remainder of the d a t a . With the e x c e p t i o n of Pb, a b s o l u t e m e t a l v a l u e s f o r s u b d r i f t 1715 West are comparable i n range and p r o p o r t i o n (A:B:C p o p u l a t i o n s ) w i t h the r e s t of the f o o t w a l l d a t a . Lead v a l u e s a r e an o r d e r of magnitude l o w e r , but do not account s o l e l y f o r the r e l a t i v e i n c r e a s e i n s i l v e r . P o l i s h e d s e c t i o n s i n d i c a t e l e s s g a l e n a and i t s ' r e l a t e d s u l p h o s a l t s and a g r e a t e r p r o p o r t i o n of p y r a r g y r i t e 77 and a r g e n t i t e . T h i s s u g g e s t s a l a t e s tage Ag m i n e r a l i z a t i o n f o r the 1715 West s u b d r i f t p a r t of the mine. REFERENCES CITED Andrew, A., Godwin, C.I. and S i n c l a i r , A . J . 1984. M i x i n g l i n e i s o c h r o n s : a new i n t e r p r e t a t i o n of g a l e n a l e a d i s o t o p e d a t a from s o u t h e a s t e r n B r i t i s h C o lumbia. Economic Geology, 79, pp. 919-932. A r c h i b a l d , D.A., G l o v e r , J.K., P r i c e , R.A., F a r r a r , E. and C a r m i c h a e l , D.M. 1983. Geochronology and t e c t o n i c i m p l i c a t i o n s of magmatism and metamorphism, s o u t h e r n Kootenay Arc and n e i g h b o u r i n g r e g i o n s , s o u t h e r n B r i t i s h C o lumbia. P a r t I : J u r a s s i c t o m i d - C r e t a c e o u s . Canadian J o u r n a l of E a r t h S c i e n c e s , 20, pp. 1891-1913. A t k i n s o n , B. K. 1976. D e f o r m a t i o n mechanism maps f o r p o l y c r y s t a l l i n e g a l e n a . E a r t h and P l a n e t a r y S c i e n c e s L e t t e r s , 29, pp. 210-218. Bateman, A. M. 1925. Notes on s i l v e r - l e a d d e p o s i t s of S l o c a n D i s t r i c t , B r i t i s h C o lumbia, Canada. Economic Geology, 20, pp. 554-572. Brame, S. 1979. M i n e r a l i s a t i o n near the n o r t h e r n , margin of the N e l s o n B a t h o l i t h . M.Sc. t h e s i s , U n i v e r s i t y of A l b e r t a , Edm., 146 p. B r e b r i c k , R. F. and S c a n l o n , W. W. 1957. Ch e m i c a l e t c h e s and e t c h p i t p a t t e r n s on PbS c r y s t a l s . J o u r n a l of Chemical P h y s i c s , 27, pp. 607-608 C a i r n e s , C. E. 1934. S l o c a n m i n i n g camp, B r i t i s h Columbia. G e o l o g i c a l Survey of Canada, Memoir 173, 137 p. C l a r k , B. R., P r i c e , F. R. and K e l l y , W. C. 1977. E f f e c t s of a n n e a l i n g on d e f o r m a t i o n t e x t u r e s i n g a l e n a . C o n t r i b u t i o n s t o M i n e r a l o g y and P e t r o l o g y , 64, pp.149-165. Cox, J . 1979. The geology of the northwest margin of the N e l s o n b a t h o l i t h , B r i t i s h Columbia. M.Sc. t h e s i s , U n i v e r s i t y of A l b e r t a , Edm., 95 p. Duncan, I . J . , P a r r i s h , R. P. and Armstrong, R. L. 1979. Rb/Sr geochronology of the p o s t - t e c t o n i c i n t r u s i v e e v e n t s i n the Omineca C r y s t a l l i n e B e l t , s o u t h e a s t e r n B r i t i s h Columbia ( a b s t r a c t ) . C o r d i l l e r a n S e c t i o n of the G e o l o g i c a l A s s o c i a t i o n of Canada, Vancouver, B.C., Program and A b s t r a c t s , p.15 G o l d s m i t h , L. B. 1984. A q u a n t i t a t i v e a n a l y s i s of some v e i n - t y p e m i n e r a l d e p o s i t s i n s o u t h e r n B r i t i s h Columbia. M.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h C o l u m b i a , Van., 86 P-78 79 G o l d s m i t h , L. B. 1981. High-grade s i l v e r - l e a d d i s c o v e r y , summary of e x p l o r a t i o n a c t i v i t i e s , 1980 H a l l m i n e r a l c l a i m group, S l o c a n m i n i n g d i v i s i o n , Sandon, B r i t i s h C o l u m b i a , p r i v a t e r e p o r t p r e p a r e d f o r Hallmac Mines L t d . , 30 p. H a l l , W. E. and Czamanske, G. K. 1972. M i n e r a l o g y and t r a c e element c o n t e n t of the Wood R i v e r l e a d - s i l v e r d e p o s i t s , B l a i n e c o u n t y , Idaho. Economic Geology, 67, pp.350-361. Hoda, S.N. and Chang, L. L. Y. 1975. Phase r e l a t i o n s i n the systems PbS-Ag 2S-Sb 2S 3 and P b S - A g 2 S - B i 2 S 3 . American M i n e r a l o g i s t , 60, pp. 621-633. Hedley, M. S. 1952. Geology and ore d e p o s i t s of the Sandon a r e a , S l o c a n m i n i n g camp, B r i t i s h C olumbia. B r i t i s h Columbia Department of Mines and P e t r o l e u m R e s o u r c e s , B u l l e t i n 29, 130 p. McClay, K. R. 1977. D i s l o c a t i o n e t c h p i t s i n g a l e n a . T e c t o n o p h y s i c s , 40, T1-T8. McClay, K. R. 1980. Sheared g a l e n a ; t e x t u r e s and m i c r o s t r u c t u r e s . J o u r n a l of S t r u c t u r a l Geology. 2, no.1/2, pp. 227-234. McClay, K. R. 1984. S t r u c t u r a l g eology of s t r a t i f o r m l e a d - z i n c d e p o s i t s : c a s e h i s t o r i e s . G e o l o g i c a l A s s o c i a t i o n of Canada, C o r d i l l e r a n S e c t i o n , S h o r t Course Number 2 ( p a r t I I ) . 150 p. McClay, K. R. and A t k i n s o n , B. K. 1977. E x p e r i m e n t a l l y i n d u c e d k i n k i n g and a n n e a l i n g of a s i n g l e c r y s t a l of g a l e n a . T e c t o n o p h y s i c s , 39, pp. 175-189. Nguyen, K. K., S i n c l a i r , A. J . and L i b b y , W. G. 1968. Age of the n o r t h e r n p a r t of the N e l s o n b a t h o l i t h . Canadian J o u r n a l of E a r t h S c i e n c e s , 5, pp. 955-957. O r c h a r d , M. J . 1985. C a r b o n i f e r o u s , Permian and T r i a s s i c c o nodants from the c e n t r a l Kootenay A r c : c o n s t r a i n t s on the age of the M i l f o r d , K a s l o and S l o c a n Groups, i n C u r r e n t R e s e a r c h , P a r t A, G e o l o g i c a l Survey of Canada, Paper 85-1A, pp. 287-300. O r r , J . F. W. 1971. M i n e r a l o g y and c o m p u t e r - o r i e n t e d study of m i n e r a l d e p o s i t s i n S l o c a n C i t y camp, N e l s o n m i n i n g d i v i s i o n , B r i t i s h C olumbia. M.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h C o lumbia, Van., 143 p. Ramdohr, P. 1969. The ore m i n e r a l s and t h e i r i n t e r g r o w t h s . Pergamon P r e s s , New York, 1174 p. R e i n s b a k k e n , A. 1968. F l u i d i n c l u s i o n s t u d i e s of gangue 80 m i n e r a l s from the S l o c a n m i n i n g d i s t r i c t , B r i t i s h C o lumbia. B.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h Columbia. Van., 73 p. Re y n o l d s , P. H. and S i n c l a i r , A. J . 1971. Rock and o r e - l e a d i s o t o p e s from the N e l s o n b a t h o l i t h and the Kootenay A r c , B r i t i s h C o lumbia, Canada. Economic Geology, 66, pp. 259-266. Robin s o n , M. C. 1948. An a n a l y s i s of the depth problem i n the S l o c a n m i n i n g camp, B r i t i s h C olumbia. B.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h C o lumbia, Van., 98 p. Robins o n , M. C. c i r c a 1950. G e o l o g i c a l s e t t i n g and r e l a t i o n s h i p s of the s i l v e r - l e a d - z i n c ore d e p o s i t s of the S i l v e r t o n a r e a , S l o c a n m i n i n g camp. U n p u b l i s h e d Ross, J . V. and K e l l e r h a l s , P. 1968. E v o l u t i o n of the S l o c a n S y n c l i n e i n s o u t h - c e n t r a l B r i t i s h C olumbia. Canadian J o u r n a l of E a r t h S c i e n c e s , 5, pp. 851-872. S i n c l a i r , A. J . 1976. A p p l i c a t i o n of p r o b a b i l i t y i n m i n e r a l e x p l o r a t i o n . S p e c i a l Volume Number 4, A s s o c i a t i o n of E x p l o r a t i o n Geochemists, Richmond, B r i t i s h C olumbia, 95 P-S i n c l a i r , A. J . and T e s s a r i , 0. J . 1980. V e i n g e o c h e m i s t r y , an e x p l o r a t i o n t o o l i n Keno H i l l camp, Yukon T e r r i t o r y , Canada. J o u r n a l of Geochemical E x p l o r a t i o n , 14, pp. 1-24. Uglow, W. L. 1917. G n e i s s i c g a l e n a ore from the S l o c a n d i s t r i c t , B r i t i s h C o lumbia. Economic Geology. 12, pp. 643-662. 3. SULPHIDE MINERALOGY AND TRACE METAL DISTRIBUTION WITHIN  UPPER SLOCAN AND LOWER R6SSLAND GROUPS, SLOCAN MINING CAMP, BRITISH COLUMBIA 3.1 INTRODUCTION Black c l a s t i c rocks of the Slocan Group host most of the more than 200 Ag-Pb-Zn-Au vein deposits of the Slocan mining camp, the remainder l i e within the Nelson batholith. Within the c l a s t i c sequence, layers and tectonic zones r i c h in organic(?) carbon are conspicuous due to their high pyrite contents. Studies of modern sediments indicate a direc t r e l a t i o n between sulphide abundance and organic content (Berner, 1970) and imply a synsedimentary/diagenetic o r i g i n for the sulphides. These carbon-rich, black shales (organic carbon >5%) are enriched in trace metals and have been postulated as l i k e l y source beds for mineral deposits (Boyle, 1968; Marmo, 1969), or a l t e r n a t i v e l y , metal sinks because of metal immobility under reducing conditions. This study reports on the trace metal abundances of four separate l i t h o l o g i c units of the Late T r i a s s i c Slocan Group and lower portions of the Early Jurassic Rossland Group. A t o t a l metal budget for the sedimentary/volcanic package can be postulated to test the l i k l i h o o d of a sedimentary source for metals in the vein deposits. More p r a c t i c a l from an exploration point i s establishing whether the carbon and sulphide enriched horizons 1) acted as 'source beds' and consequently control the d i s t r i b u t i o n of 81 82 v e i n d e p o s i t s , and/or 2) c o n s t i t u t e e p i g e n e t i c h a l o e s about low-grade, high-tonnage d e p o s i t s t h e m s e l v e s . As p a r t of the study of t r a c e m e t a l abundances s u l p h i d e s from the sediments were s t u d i e d m i c r o s c o p i c a l l y t o determine t h e i r m i n e r a l o g y , t e x t u r e and p a r a g e n e t i c r e l a t i o n s h i p s . The purpose of t h i s study was t w o f o l d : 1) t o e s t a b l i s h the s u l p h i d e as e i t h e r a u t h i g e n i c ( i n the br o a d e s t sense of the word) or a l l o g e n i c , t h u s a l l o w i n g a more m e a n i n g f u l comparisons of l i t h o g e o c h e m i c a l d a t a between s u l p h i d e - r i c h and s u l p h i d e - p o o r s e d i m e n t s , and 2) t o s e l e c t a l i m i t e d s u i t e of samples f o r s u l p h i d e P b - i s o t o p e a n a l y s i s . D e s c r i p t i o n s of l a t e or i n t r o d u c e d s u l p h i d e s ( i . e . c r o s s c u t t i n g f r a c t u r e - f i l l i n g s ) r e c e i v e o n l y c u r s o r y a t t e n t i o n because o t h e r s t u d i e s of v e i n m i n e r a l assemblages have been made ( C a i r n e s , 1935; Ro b i n s o n , 1952; O r r , 1969; Logan, 1986). 3.2 SULPHIDE MINERALOGY P y r i t e i s the most abundant and g e n e r a l l y o n l y v i s i b l e s u l p h i d e w i t h i n the sediments. P y r r h o t i t e i s l o c a l l y dominant where sediments a r e b l e a c h e d and/or s i l i c i f i e d , s u g g e s t i n g i t t o be a metamorphic or h y d r o t h e r m a l a l t e r a t i o n p r o d u c t of a u t h i g e n i c p y r i t e . P y r i t e o c c u r s i n the f o l l o w i n g forms: 1) f r a m b o i d s , s p h e r o i d a l a g g r e g a t e s of m i c r o c r y s t a l l i t e s , 2) a n h e d r a l p o r p h y r o b l a s t s composed of f r a m b o i d s , o r g a n i c m a t e r i a l , and t r a c e s of base metal s u l p h i d e s i n a porous 'mesh-type' 83 t e x t u r e , 3) i n c l u s i o n - f r e e a n h e d r a l t o s u b h e d r a l g r a i n s of massive t e x t u r e , and 4) i d i o b l a s t i c g r a i n s . F i g u r e 3-1 i l l u s t r a t e s the t e x t u r a l r e l a t i o n s between the f i r s t t h r e e forms of p y r i t e w i t h i n a c a r b o n - r i c h s l a t e . S u l p h i d e s of z i n c , c o p p e r , l e a d and n i c k e l a r e i n g e n e r a l a t l e a s t an o r d e r of magnitude l e s s abundant than p y r i t e . These base m e t a l s u l p h i d e s r a r e l y o c c u r s e p a r a t e from p y r i t e , b e i n g most common as i n c l u s i o n s w i t h i n porous p o r p h y r o b l a s t i c p y r i t e . C h a l c o p y r i t e and s p h a l e r i t e l o c a l l y r e p l a c e f r a m b o i d a l p y r i t e a l t h o u g h t h i s i s not common. 3.3 PARAGENESIS S u l p h i d e t e x t u r e s and t h e i r d i s t r i b u t i o n w i t h i n the S l o c a n sediments d e f i n e t h r e e main s t a g e s of s u l p h i d e f o r m a t i o n . P a r a g e n e t i c a l l y t h e s e s t a g e s a r e i n t e r p r e t e d t o c o r r e s p o n d t o the f o l l o w i n g g e n e t i c p r o c e s s e s or e v e n t s : 1) sy n s e d i m e n t a r y and d i a g e n e t i c , 2) metamorphic r e c r y s t a l l i z a t i o n / r e d i s t r i b u t i o n , b o th c o n t a c t and r e g i o n a l and 3) f r a c t u r i n g and h y d r o t h e r m a l v e i n d e p o s i t i o n . McKibben and E l d e r s (1985) i n t e r p r e t s u l p h i d e s d i s t r i b u t e d t h r o u g h the S a l t o n Sea geothermal system i n a comparable manner. D i s t r i b u t i o n w i t h i n t h i s modern day geothermal system of d i a g e n e t i c , metamorphic and h y d r o t h e r m a l s u l p h i d e s i s a f u n c t i o n of depth and t e m p e r a t u r e . The S l o c a n s e d i m e n t a r y r o c k s have undergone d e f o r m a t i o n , i n t r u s i o n , a p r o b a b l e T e r t i a r y t h e r m a l event and e r o s i o n / a l l of which c o m p l i c a t e the d i s t r i b u t i o n of s u l p h i d e forms. Few o c c u r r a n c e s of 84 _50_ F i g u r e 3 - 1 . T h r e e d i s t i n c t f o r m s o f p y r i t e , I : f r a m b o i d s , I I : o p e n - m e s h / p o r o u s , a n d I I I : m a s s i v e . R e f l e c t e d l i g h t p h o t o m i c r o g r a p h o f s a m p l e P A - 6 A - 8 , t a k e n f r o m s l a t e b e l t o n R e c o M t . 85 form-1 s u l p h i d e s are preserved, r e l i c t form-1 p y r i t e o v e r p r i n t e d by form-2 i s the norm and adjacent to v e i n d e p o s i t s a l l three s u l p h i d e types can be found together. A summary of the paragenesis i s presented i n a framework of the three main 'stages of m i n e r a l i z a t i o n ( F i g . 3-2) each of which i s d i s c u s s e d below. 3.3.1 DIAGENETIC SULPHIDES • D i a g e n e s i s i s used here to i n c l u d e a l l p h y s i c a l geochemical and b i o c h e m i c a l changes o c c u r r i n g from the time of sedimentation, compaction, up to and i n c l u d i n g l i t h i f i c a t i o n . Generation of s u l p h i d e s d u r i n g d i a g e n e s i s i s evident from the presence of p y r i t e i n present day marine and fresh-water sediments, where i t occurs as replacements of organic s t r u c t u r e s ; as framboids, i n marine sediments (Sweeney and Kaplan, 1973) and i n peat bogs ( L e t t and F l e t c h e r , 1980); as c o n c r e t i o n s (Tikhomirova, 1960); and as disseminated i d i o b l a s t i c g r a i n s . A t h e o r e t i c a l model for sedimentary s u l p h i d e formation on the sea f l o o r i s presented i n Appendix B. T y p i c a l Slocan framboids vary from 10 to 24 M i n diameter. The s m a l l e r examples g e n e r a l l y show a d e l i c a t e t e x t u r e c o n s i s t i n g of equant i d i o b l a s t i c c r y s t a l s <1 u i n s i z e . Larger framboids g e n e r a l l y lack the c r y s t a l morphology d i s p l a y e d so d e l i c a t e l y by s m a l l e r framboids. Framboids a l s o occur i n c l u s t e r s of f i v e to ten i n v a r i o u s stages of c o a l e s c e n c e . 86 STAGES OF SULPHIDE MINERALIZATION PYRITE PYRRHOTITE SPHALERITE CHALCOPYRITE MILLERITE GALENA *AG-SULPHOSALT *AG SULPHIDES DEPOS DIAGENETIC framboids c o n c r e t i o n s METAMORPHIC REGIONAL CONTACT porous 'open-mesh' 1 p o r p h y r o b l a s t i c TION 225 Ma HYDROTHERMAL LITHIFlCATION FRACTURING LODE FORMATION INTRUSION (NELSON BATH.) 160 +/-6 Ma * not i d e n t i f i e d i n sediments F i g u r e 3-2. P a r a g e n e s i s of sed i m e n t a r y s u l p h i d e m i n e r a l s . D e c r e a s i n g o r d e r of abundance ( p y r i t e t o gale n a ) a p p l i e s o n l y t o D i a g e n e t i c and Metamorphic s t a g e s . The h o r i z o n t a l d i s t a n c e between s t a g e s i s not c a l i b r a t e d f o r t i m e . Age of d e p o s i t i o n i s from O r c h a r d (1985) and age of i n t r u s i o n i s from H a r r i s o n (1985). 87 P y r i t e c o n c r e t i o n s occur w i t h i n carbonaceous i n t e r v a l s of s l a t e , a r g i l l i t e and t u f f a c e o u s beds i n the study a r e a . C o n c e n t r i c and l e n t i c u l a r ( c o n formable t o bedding) t y p e s , i n s i z e s which v a r y c o n s i d e r a b l y t o a maximum 1.5 by 4.0 cm a r e common. W i t h i n the c o n c r e t i o n s , c o n t r a c t i o n c r a c k s , b o t h r a d i a l and i r r e g u l a r a r e l i n e d w i t h massive r e c r y s t a l l i z e d ( ? ) p y r i t e , t r a c e amounts of c h a l c o p y r i t e and c a l c i t e . C o n c e n t r i c v a r i a t i o n s i n g r a i n s i z e and c r y s t a l l i n i t y i n d i c a t e c h a n g i n g c o n d i t i o n s of p r e c i p i t a t i o n . A g e n e r a l i n c r e a s e i n c r y s t a l l i n i t y and g r a i n s i z e outward from the c e n t e r i s enhanced by e t c h i n g w i t h 1:1 HN0 3. Porous s u b h e d r a l s u l p h i d e masses and p o r p h y r o b l a s t s i n both s u b o r d i n a t e - g r a i n c o n t a c t r e l a t i o n s h i p s w i t h f r a m b o i d s and rimming framboids i n d i c a t e l a t e r p y r i t e c r y s t a l l i z a t i o n under c o n d i t i o n s of p r e c i p i t a t i o n d i f f e r i n g from th o s e which produced f r a m b o i d s . T h i s s t a g e , thought t o r e p r e s e n t l a t e d i a g e n e s i s , i s marked by i n c l u s i o n s of s u b o r d i n a t e amounts of o t h e r s u l p h i d e s , such as s p h a l e r i t e , c h a l c o p y r i t e and m i l l e r i t e i n d e c r e a s i n g o r d e r of abundance. The t r a c e amounts of base-metal s u l p h i d e i n c l u s i o n s i n d i c a t e t h a t Zn, Cu, and N i were a v a i l a b l e d u r i n g p y r i t e p r e c i p i t a t i o n . S t r a t i f o r m s p h a l e r i t e and g a l e n a w i t h t r a c e p y r i t e has been i d e n t i f i e d from a s i n g l e l o c a t i o n near Reco Mt. ( F i g . 3-3). The s u l p h i d e s occupy a narrow 0.5 cm wide bed or l a y e r i n b l a c k a r g i l l i t e s which c o n t a i n c r o s s c u t t i n g t e n s i o n f r a c t u r e s m i n e r a l i z e d w i t h h y d r o t h e r m a l - t y p e m i n e r a l assemblages. S t r a t i f o r m s p h a l e r i t e i s i n t e r s t i a l t o m i n e r a l 1 0 O M 88 F i g u r e 3-3. S t r a t i f o r m s p h a l e r i t e ( l i g h t g r e y ) , i n t e r g r o w n w i t h c a r b o n a t e (medium g r e y ) and minor g a l e n a ( w h i t e ) . SEM b a c k s c a t t e r p h o t o m i c r o g r a p h of sample NB 1409, l o c a t e d on road s o u t h of Soho mine. 89 g r a i n s , i n a c e m e n t a t i o n t e x t u r e ( r e p l a c e m e n t ) ; g a l e n a i s s u b o r d i n a t e o c c u r i n g as i n c l u s i o n s i n s p h a l e r i t e ( F i g . 3-3). T e x t u r e s suggest g a l e n a formed a f t e r s p h a l e r i t e . No s i l v e r m i n e r a l s were i d e n t i f i e d w i t h i n the l a y e r e d s u l p h i d e s . 3.3.2 METAMORPHIC SULPHIDES The metamorphic s t a g e b e g i n s a f t e r l i t h i f i c a t i o n and i s c h a r a c t e r i z e d by i n c r e a s e d temperature and p r e s s u r e , which produce r e c r y s t a l l i z a t i o n , g e n e r a l i n c r e a s e i n g r a i n s i z e and new m i n e r a l assemblages. S u l p h i d e f a b r i c s i n d i c a t e c o n c o m i t a n t d e f o r m a t i o n . R e g i o n a l metamorphism of the sediments i s below b i o t i t e - g r a d e g r e e n s c h i s t f a c i e s . At t h i s low grade of metamorphism, r e l i c t d i a g e n e t i c forms s u r v i v e and a wide v a r i e t y of secondary s u l p h i d e forms a r e produced. I n c l u d e d a r e a l l s t a g e s o f : g r a i n growth, r e c r y s t a l l i z a t i o n and r e p l a c e m e n t . I d e n t i c a l t e x t u r e s have d e v e l o p e d d u r i n g c o n t a c t metamorphism. These a r e of p a r t i c u l a r use p a r a g e n e t i c a l l y as t h e i r f o r m a t i o n c o i n c i d e s w i t h i n t r u s i o n of the N e l s o n b a t h o l i t h . C o n t a c t metamorphic assemblages a d j a c e n t t h i s b a t h o l i t h (and up t o 1.5 km away) suggest t e m p e r a t u r e s and depth of emplacement on the o r d e r of 550°C and 10 km ( A r c h i b a l d et a l . , 1984). D u r i n g metamorphism p y r i t e growth i s accommodated by e i t h e r o v e r g r o w t h t e x t u r e s which i n c l u d e s i m p l e rims and complex zoned forms ( F i g . 3-4a) or by c o a l e s c e n c e of a d j a c e n t c r y s t a l s l e a d i n g t o f o r m a t i o n of p o r p h y r o b l a s t s . F i g u r e 3-4. A: Zoned i n c l u s i o n s of s p h a l e r i t e ( l i g h t g r e y ) and r u t i l e (medium grey) i n p y r i t e i n d i c a t e d i f f e r e n t s t a g e s / c o n d i t i o n s of mineral growth from t h a t which produced the l e s s porous t e x t u r e d rim ( r e f l e c t e d l i g h t photomicrograph of sample from F o u r t h of J u l y d e p o s i t ) . B: Synkinematic r e c r y s t a l l i z a t i o n developed p y r i t e p r e s s u r e shadow a d j a c e n t e a r l i e r subhedral c r y s t a l . I n c l u s i o n s i n ' t a i l ' i n c l u d e c h a l c o p y r i t e ( l i g h t grey) and monzanlte ( b r i g h t white, c e n t e r of p h o t o ) . SEM b a c k s c a t t e r photomicrograph of sample ww-2202A. C: P y r i t e cubes i n c l u d e d i n p y r r h o t i t e mass, s u g g e s t i n g p y r i t e replacement by p y r r h o t i t e . R e f l e c t e d l i g h t photomicrograph of sample BO 2004. D: P y r r h o t i t e as l e n s o i d , i r r e g u l a r masses which p a r a l l e l metamorphic f o l i a t i o n i n s l a t e . R e f l e c t e d l i g h t photomicrograph of sample A1r-99. 91 92 Overgrowths of framboids a r e common, except those s i t u a t e d i n carbonaceous p a r t i n g s ( c l e a v a g e ?) or impermeable s h a l e s . Growth z o n i n g i s e v i d e n t from the d i s t r i b u t i o n of i n c l u s i o n s and i n d i c a t e s e i t h e r r a p i d c r y s t a l l i z a t i o n or d i s c o n t i n u o u s s t a g e s of growth ( F i g . 3-4a). The d i s t r i b u t i o n of n o n - s u l p h i d e i n c l u s i o n s of d e t r i t a l and d i a g e n i c m i n e r a l s suggest t h e i r i n c o r p o r a t i o n d u r i n g i n s i t u - o v e r g r o w t h of p y r i t e . A p a t i t e , b r i t h o l i t e [(Yb,Gd,Er,Dy) 5(SiO«,P0„) 3(OH,F) an a p a t i t e group m i n e r a l ] and u b i q u i t o u s t i t a n i u m o x i d e a r e i n t e r p r e t e d t o be d i a g e n e t i c i n o r i g i n . D e t r i t a l m i n e r a l s i n c l u d e p r e d o m i n a n t l y r e s i d u a l carbonaceous m a t e r i a l and i n one case monazite was i d e n t i f i e d . Metamorphic r e c r y s t a l l i z a t i o n d e v e l o p s s u l p h i d e t e x t u r e s which r e f l e c t a c r y s t a l l o b l a s t i c s e r i e s t h a t i s r e l a t e d t o a tendancy t o id i o m o r p h i s m and not a s p e c i f i c p a r a g e n e t i c sequence. P y r i t e i s h i g h i n the c r y s t a l l o b l a s t i c s e r i e s ( S t a n t o n , 1964: p y r i t e >> p y r r h o t i t e > s p h a l e r i t e > c h a l c o p y r i t e > g a l e n a ) , which a c c o u n t s f o r p o i k i l o b l a s t i c t e x t u r e s and i t s u b i q u i t o u s c u b i c form where c r y s t a l l i z a t i o n i s c o m p l e t e . The a d d i t i o n a l s u l p h i d e s occupy i n c l u s i o n or m a t r i x - t y p e forms as a r e s u l t of t h e i r s u b o r d i n a t e p o s i t i o n s i n the c r y s t a l l o b l a s t i c s e r i e s but t h i s c o u l d e q u a l l y be r e l a t e d t o t h e i r minor abundances. The v a r i e t y and abundance of t r a c e m e t a l s u l p h i d e i n c l u s i o n s i n c r e a s e s w i t h the degree of c r y s t a l l i z a t i o n . Whether these s u b s i d i a r y s p e c i e s (Cu, N i and Z n - s u l p h i d e s ) have been s e g r e g a t e d from the p y r i t e s t r u c t u r e or were i n t r o d u c e d d u r i n g r e c r y s t a l l i z a t i o n i s 93 u n c l e a r . S y n k i n e m a t i c r e c r * y s t a l l i z a t i o n reduces the tendancy t o idio m o r p h i s m i n response t o d i r e c t e d s t r e s s e s . P r e s s u r e s o l u t i o n ( ? ) and/or d i r e c t e d c r y s t a l growth d u r i n g d e f o r m a t i o n has produced p y r i t e g r a i n s which a r e f l a t t e n e d p e r p e n d i c u l a r t o s c h i s t o s i t y . These are commonly accompanied by e i t h e r q u a r t z , q u a r t z and car b o n a t e and r a r e l y s u l p h i d e p r e s s u r e shadows ( F i g . 3-4b). Areas of c o n t a c t metamorphism a r e c h a r a c t e r i z e d by h o r n f e l s i c r e c r y s t a l l i z a t i o n of sediments and p y r r h o t i t e as the dominant or e x c l u s i v e i r o n s u l p h i d e . R e l i c t p y r i t e o c c u r s as ragged, commonly f r a c t u r e d a n h e d r a l masses t h a t are e i t h e r v e i n e d by s p h a l e r i t e and r a r e l y c h a l c o p y r i t e , or l o c a l l y rimmed by p y r r h o t i t e ( F i g . 3-4c). P y r r h o t i t e l a c k s the s t r o n g tendancy f o r i d i o m o r p h i s m p o s s e s s e d by p y r i t e , c o n s e q u e n t l y i t forms ragged, f o l i a t i o n - p a r a l l e l masses, cementing or i n t e r s t i a l t o s u l p h i d e and s i l i c a t e m i n e r a l g r a i n s ( F i g . 3-4d). Replacement of p y r i t e by p y r r h o t i t e r e s u l t s i n the p r o d u c t i o n of s u l p h u r a c c o r d i n g t o the r e a c t i o n : F e S 2 — F e , _ x S + S The p a r t i a l p r e s s u r e of s u l p h u r c o n t r o l s the r e a c t i o n and an open system would ensure the r e a c t i o n i s d r i v e n t o the r i g h t . Metamorphism a t depth c o u l d r e l e a s e i m p o r t a n t amounts of s u l p h u r which c o u l d then m i g r a t e i n t o h i g h e r l e v e l 94 e p i g e n e t i c s t r u c t u r e s . 3.3.3 HYDROTHERMAL SULPHIDES The h y d r o t h e r m a l s t a g e i n c l u d e s f r a c t u r i n g , a l t e r a t i o n and f r a c t u r e - f i l l i n g r e l a t e d t o c i r c u l a t i o n of heated f l u i d s . T h i s s t a g e , was p r o b a b l y i n i t i a t e d d u r i n g metamorphism and r e p r e s e n t s ' e v o l v e d ' metamorphic f l u i d c i r c u l a t i o n and d e p o s i t i o n m a i n t a i n e d by i n t r u s i v e r e l a t e d heat s o u r c e s . F l u i d i n c l u s i o n s t u d i e s of v e i n gangue m i n e r a l s i n d i c a t e d e p o s i t i o n from d i l u t e b r i n e s (no daughter c r y s t a l s ) i n response t o d e c r e a s e s i n temperature i n c o n t r a s t t o a p r e s s u r e drop. Temperatures of f i l l i n g ( u n c o r r e c t e d f o r p r e s s u r e ) average 225°C ( R e i n s b a k k e n , 1968). S l i g h t l y h i g h e r t e m p e r a t u r e s a r e suggested from S - i s o t o p e a n a l y s i s of g a l e n a - s p h a l e r i t e p a i r s (Brame, 1979). T e x t u r a l l y a continuum e x i s t s between the metamorphic and h y d r o t h e r m a l s t a g e s and t o d i s t i n g u i s h the two i s o f t e n d i f f i c u l t . H y d rothermal i s t h e r e f o r e used f o r those m i n e r a l s which occupy c r o s s c u t t i n g s t r u c t u r e s . The f o l l o w i n g i s a d e s c r i p t i o n of t h e s u l p h i d e s l o c a t e d p e r i p h e r a l t o t h e s e v e i n s t r u c t u r e s . P e r i p h e r a l t o v e i n d e p o s i t s , i r o n s u l p h i d e s a r e s u b h e d r a l , and g e n e r a l l y show rounded c r y s t a l edges. The abundance and d i s t r i b u t i o n of s p h a l e r i t e , g a l e n a 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 c r e a s e and become d i s t i n c t i v e i n some cases a d j a c e n t t o l o d e s t r u c t u r e s . P y r i t e commonly 95 F i g u r e 3-5. P r i m a r y sedimentary c r o s s - b e d d i n g p r e s e r v e d by p r e f e r r e n t i a l replacement of l i m y l a y e r s by p y r i t e . Sample NB 1401 A, ( F i g . 3 - 5 ) was taken from h a n g i n g w a l l a d j a c e n t N o r t h e r n B e l l e v e i n . 96 c o n t a i n s z o n a l d i s t r i b u t i o n s of g a l e n a , s p h a l e r i t e and c h a l c o p y r i t e i n a d d i t i o n t o p e r i p h e r a l replacement by the same m i n e r a l s . The form and d i s t r i b u t i o n of s u l p h i d e s i s i n t e r p r e t e d as a h y d r o t h e r m a l f l o o d i n g - t y p e p r o c e s s which has i n t r o d u c e d m a t e r i a l and r e c r y s t a l l i z e d e a r l i e r s u l p h i d e s . T h i s w a l l rock i m p r e g n a t i o n by v e i n f l u i d s i s r a r e u n l e s s a r e a c t i v e l i t h o l o g y (eg. l i m e s t o n e ) i s e n c o u n t e r e d ( F i g . 3-5) or w i d e s p r e a d f r a c t u r i n g has o c c u r r e d . For t h a t reason t h e r e a r e no r e a l e x p l o r a t i o n h a l o e s or e n v e l o p e s d e v e l o p e d much beyond the a c t u a l h a n g i n g w a l l / f o o t w a l l of the l o d e s . Common v e i n m i n e r a l o g y f o r d e p o s i t s of the Camp i s g a l e n a , s p h a l e r i t e , p y r i t e , s i l v e r s u l p h o s a l t s , s i l v e r s u l p h i d e s and c h a l c o p y r i t e . Gangue m i n e r a l s i n c l u d e s i d e r i t e , q u a r t z and c a r b o n a t e . Comparing t h i s w i t h the sediment m i n e r a l o g y i t appears o n l y the s i l v e r m i n e r a l s a r e l a c k i n g or u n i d e n t i f i e d w i t h i n s e d i m e n t s . 3.4 GEOCHEMISTRY 3.4.1 SAMPLING AND ANALYTICAL PREPARATION Rock samples were c o l l e c t e d from o u t c r o p s r e p r e s e n t a t i v e of s e c t i o n s w i t h i n the S l o c a n Group and t h a t p o r t i o n of the R o s s l a n d Group which o c c u r s w i t h i n the study a r e a ( F i g . 3-6 and 3-7). Cox (1979) on the b a s i s of l i t h o g e o c h e m i s t r y i n d i c a t e d t h a t the sediments were an u n l i k e l y source f o r the v e i n d e p o s i t s . As a r e s u l t , REGIONAL GEOLOGY AND SAMPLE LOCATION MAP (I) L O C A T I O N M A P STUDY AREA * BRITISH COLUMBIA WASHINGTON LEGEND QJJ] Biolite quart* monzontte g*?] Feldspar porphyry Helton granodiorte (porphyritic) | | Slocan Group clastic sediments Lata P and/or T E3 N«moLahe metaaedtments E33 M f l f , i n congtomerate ffYYl Kaslo Group volcanic s SLOCAN LITHOLOOICAL SUCCESSION I o I Thln. interbedded sandy, Umey and I .I tuflacaoua rocks Slate with limestone bads SYMBOLS * Geochemical sample location ® Pyrite Pb-isotope sample location — — - Qeotoflical contacts (defined, assumed) <ZLZ5 Lithotooical contacts « M Lode trends , Fault (defined, assumed) Otology compttad Irani: Caunai 1834 Hadley. IB4& and 1952 Ktapacki and Whaelaf. 1885 Lntia. 1680 Pariiiri. 1885 Read. 1078 20O0 3000 4000 5000m SCALE F i g u r e 3-6. Regional geology of -the c e n t r a l Slocan mining camp, showing rock geochemical, isotope and p e t r o g r a p h i c sample 1 ocat ions. REGIONAL GEOLOGY AND SAMPLE LOCATION MAP (II) <J3 CO Figure 3-7. Regional geology of the northeastern Slocan mining camp, showing rock geochemical and petrographic sample l o c a t i o n s . 99 m e t h o d i c a l s t r a t i g r a p h i c i n t e r v a l s a m p l i n g was not c a r r i e d o u t , but 'source-bed' type of h o r i z o n ( s ) were t a r g e t e d . Sampling i n c l u d e d carbonaceous u n i t s , p y r i t i c h o r i z o n s , t u f f a c e o u s i n t e r v a l s and v o l c a n i c s . Rock sample d e s c r i p t i o n s a re i n Appendix C. A l l samples were examined c l o s e l y and any c r o s s c u t t i n g f r a c t u r e s were removed p r i o r t o c r u s h i n g and g r i n d i n g . Thus, i t was hoped each sample r e p r e s e n t e d m e t a l abundances of the o r i g i n a l s e d i m e n t a r y (± d i a g e n e t i c ± metamorphic) r o c k s w i t h l i t t l e or no e p i g e n e t i c a d d i t i o n s . Sample a n a l y s i s (n = 69) by atomic a b s o r p t i o n s p e c t r o p h o t o m e t r y was c a r r i e d out i n N o r t h Vancouver by Vangeochem Labs L i m i t e d . The g e o c h e m i c a l d a t a i n c l u d e Pb, Zn, Ag, Co, N i , Ba, Cd, and S which t o g e t h e r w i t h means, s t a n d a r d d e v i a t i o n s and s t a n d a r d e r r o r s of the means a r e t a b u l a t e d i n s t r a t i g r a p h i c o r d e r ( T a b l e 3-1). D u p l i c a t e a n a l y s e s of samples was undertaken t o t e s t the a n a l y t i c a l p r e c i s i o n . D u p l i c a t e d a t a a r e l i s t e d i n Appendix C w i t h the mean r e l a t i v e e r r o r s . P r e c i s i o n , e s t i m a t e d as the mean r e l a t i v e e r r o r i n p e r c e n t f o r each element, a r e as f o l l o w s : Ag, 5%; Pb, Zn and N i , 20-30%; Co and Cd, 30-40%; S, 65%; and Ba, 121%. T o t a l carbon was d e t e r m i n e d f o r a s e t of f i v e p y r i t i c and carbonaceous s l a t e s (Table 3-2). Samples were c r u s h e d and ground t o -200 mesh and a n a l y s e d by Canadian M i c r o a n a l y t i c a l S e r v i c e L t d . of Vancouver. 100 Table 3-1 Slocan regional rock geochemistry (Fig. 3-6 and 3-7 indicate sample locations and Fig. 3-11 presents mean and 68 percentile plots for individual H t h o l o g i c u n i t s ) . SLOCAN GROUP (f i n e grained e l a s t i c s ) L l t h o l o g i c a l Unit "1" SAMPLE NO. PB % ZN % AG O/T CO % NI % BA % CD % S °, 4 WW W2202A .0016 .0104 .071 .0025 .0050 . 176 .00026 2 . 13 WW W2202B .0012 .0019 .062 . 0005 .0010 .016 .00006 . 12 Arithmetic mean = .0014 .0062 .066 .0015 .0030 .096 .00016 1 . 13 Std. deviation = .0002 .0060 .006 .0014 .0028 .113 .00014 1 .42 Std. error mean = .0001 .0042 .004 .0010 .0020 .079 .00010 1 .00 L l t h o l o g l c a l Unit "2" SAMPLE NO. PB % ZN % AG O/T CO % NI % BA % CD % S ° 4 CC 1501B .0030 .0105 .021 .0030 .0065 .016 .00018 1 .34 CC 1502 .0025 .0135 .006 .0035 .0040 . 096 .00029 .67 CC 1504A .0027 .0115 .026 .0045 .0035 .096 .00022 1 .03 CC 1515 .0030 .0098 .044 .0035 .0080 .016 .00019 1 . 10 CC 1516 .0020 .01 10 .017 .0040 .0040 .016 .00032 1 .32 BO B1003 .0034 .01 10 .021 .0060 .0040 .016 . 00030 1 .31 BO B1004 .0014 .01 14 .012 .0035 .0050 .056 .00037 .96 BO B1005 .0018 .0255 .017 .0035 .0055 .056 .00062 T .48 BO B1006 .0026 .0140 .029 .0050 .0040 .005 .00022 1 .85 BO B1007 .0023 .0127 .006 .0050 .0030 .056 .00026 .91 BO B1008 . 0020 .0130 .015 .0040 .0025 .096 .00021 9^1 BO 2004 .0024 .0105 .017 .0055 .0040 .056 .00026 1 .24 BO B2009 .0023 .0139 .006 .0045 .0030 .096 .00018 .68 Arithmetic mean = .0024 .0129 .018 .0043 . .0044 .052 .00028 1 . 14 Std. deviation = .0005 .0040 .01 1 .0009 .0015 .036 .00012 0 . 33 Std. error mean = .0001 .001 1 .003 .0002 .0004 .010 .00003 0 .09 L l t h o l o g l c a l Unit "Slate Bel t" SAMPLE NO. PB % ZN % AG O/T CO % NI % BA % CD % S 5 4 PA 606 .0023 .0105 .082 .0025 .0050 . 256 .00019 8 . 42 PA 606A-4 .0010 .0073 . 109 .0035 .0090 1 . 272 .00022 8 . 83 PA 606A-11 .0005 .0081 .006 .0010 .0015 . 376 .00022 , 29 PA 606A-14 .0024 .0083 .074 .0080 .0080 .136 .00031 16 . 27 CD 1404C .0065 .0090 .044 .0040 .0075 . 576 .00044 10 . 23 CD 1405C .0052 .0500 .053 .0025 .0080 .422 .00109 1 .58 CD 1406C .0060 .0135 .065 .0040 ' .0045 .096 .00044 2 . 15 CD 1408C .0052 .0111 .038 .0020 .0030 .096 .00066 . 30 CD 1410C .0016 .0014 .032 .0005 .0010 . 136 .00007 . 26 PR 1902 .0019 .0085 .015 .0030 .0060 .096 .00035 .96 PR 1904 .0022 .0099 . 106 .0040 .0155 . 196 .00012 5 . 00 Arithmetic mean = .0031 .0125 .057 .0032 .0063 . 333 .00037 4. 94 Std. deviation = .0020 .0120 .032 .0020 .0041 . 349 .00029 5. 33 Std. error mean = .0006 .0036 .009 .0006 .0012 . 105 .00009 1 . 61 1 0 1 L l t h o l o g l c a l Unit "3". SAMPLE NO. PB % ZN % AG O/T CO % NI % BA % CD % S °, *0 <* NB 1408 .0058 .0104 .017 .0030 . 0050 .096 .00017 0 .81 ID 1707 .0028 .0190 .012 .0055 .0030 .216 . .00018 1 . 13 ID 1708 .0045 . 020 .024 .0040 .0030 .005 .00027 0 .96 ID 1709 .0021 .01 10 .012 .0050 .0030 .016 .00013 0 .71 ID 1709C .0015 .0084 .012 .0035 .0050 .056 .00019 1 .05 RD 2003 .001 1 .0310 .017 .0030 .0065 .056 .00102 1 .03 RD 2004 .0017 .0170 .009 .0035 .0045 .016 .00043 1 . 46 RD 2005 .001 1 .0119 .015 .0030 .0035 .016 .00021 1 .52 RD 2006 .0017 .0120 .015 .0035 .0050 .005 .00043 1 . 35 Arithmetic mean = .0025 .0015 .015 .0038 .0043 .054 .00034 1 . 1 1 Std. deviation = .0015 .0066 .004 .0009 .0012 .068 .00028 0 . 28 Std. error mean = .0005 .0022 .001 .0003 .0004 .022 .00009 0 .09 ROSSLAND GROUP (volcanlcs and e l a s t i c s . und1vi ded) SAMPLE NO. PB % ZN % AG O/T CO % NI % BA % CD % S 5 CU CU8201 .0015 .0068 .003 .0055 .0065 .036 .00015 . 35 CU CU8204 .0019 .0126 . .012 .0045 .0065 .096 .00026 .06 CU CU8206 .0018 .0099 .006 .0050 .0060 .096 .00019 .07 CU CU8207 .0015 .0035 .006 .0030 .0020 .076 .00014 . 79 CU CU8207A .0022 .0040 .006 .0025 .0020 .036 .00010 2 .07 SS J8404S .0020 .0240 .017 .0020 .0025 . 176 .00011 .07 SS J8406S .0018 .0061 .003 .0030 .0020 .056 .00007 6 .43 SS J8407S .0020 .0164 .006 .0045 .0075 .016 .00022 . 10 SL 8201 . 002 1 .OQ45 .009 .0055 .0035 .056 .00017 .05 SL 8202 .0022 .0096 .006 .0050 .0050 . 176 .00018 1 .06 SL 8203A .0027 .0190 .Oi5 .0070 .0! 10 .096 .00038 .45 SL 8203B .0020 .0072 .006 .0065 .0021 . 176 .00019 .17 SL 8203C .0022 .0119 .009 .0060 .0075 .036 .00022 .25 SL 8204 .0020 .0085 .003 .0050 .0065 .005 .00016 .79 SL 8205 .0022 .0084 .012 • .0055 .0080 .056 .00019 .95 SL 8206 .0016 .0055 .009 .0050 .0060 .016 .00015 .31 SL 8207 .0018 .0128 .006 .0060 .0085 .016 .00015 .47 SL 8208 .0025 .0062 .006 .0055 .0060 :056 .00030 . 34 SL 8209 .0019 .0137 .009 .0055 .0085 .056 .00020 ,04 SL 8210 .0018 .0065 .006 .0035 .0045 .036 .00018 10 SL 8218 .0016 .0089 .001 .0035 .0055 .016 .00018 02 Arithmetic mean = .0019 .0098 .007 .0047 .0056 .066 .00019 0. 71 Std. deviation = .0003 .0052 .004 .0013 .0025 .053 .00007 1 . 40 Std. error mean = .0007 .001 1 .001 .0003 , 0005 .012 .00001 0. 31 EPIGENETIC MINERALIZATION (und1v i ded) SAMPLE NO. PB % ZN % AG O/T CO % NI % BA % CD % . S °/ NB 14-B . 1600 1 . 140 .629 .0030 .0040 .276 .0118 3 , .04 NB 1401A 3.6000 .0040 4.694 .0051 .0035 .016 .00054 22 . 68 NB 1409 .5600 .9600 1 .576 .0020 .0035 1 . 176 .0088 1 . . 70 NB 1410 .0O35 .0780 .141 .0055 . 0300 . 176 .00192 5 . 42 PA 606A-6 .0019 . 4400 .092 . 0030 .0140 .216 .00590 3. . 48 PA 606A-8 .0045 .0960 . 129 .0065 .0300 . 336 .00144 12 . 31 CD 1402C . 172 .0138 . 147 .0065 .0085 . 176 .00049 7 . 96 CD 1403C .0251 .0548 .071 .0025 .0065 .096 .00112 2 . 13 CD 1409C .0088 . 345 .088 .0055 .0450 .016 .0056 12 SS J8401S .0091 .2500 . 582 .0050 .0400 .096 .0057 65 SS J8402S .0047 . 2900 .965 .0050 .0450 .456 .0064 1 , . 17 SS J8403S .0020 1.4500 . 144 .0045 .0950 . 296 .00154 82 SS J8405S .0024 .5500 . 188 .0035 .0500 .016 .00035 29 Arithmetic mean = .3503 .4363 .727 .0044 .0288 . 253 .00397 4 . 20 Std. deviation = .9888 .4681 1 . 27 .0015 .0266 . 309 .00366 6 . 44 Std. error mean = .2739 . 1297 . 353 .0004 .0074 .086 .00101 1 . 78 Table 3-2 Carbon (total C) and hydrogen from Slocan, s l a t e belt ( F i g . 3-6 shows sample locations). SAMPLE LITHOLOGY ELEMENT C (%) H San 01 sl a t e 5. .25 <0. 2 WW 2B sl a t e 2. . 10 <0.2 PA 60S s 1 ate 4 .52 <0.2 PA 606 s l a t e 4 .51 <0.2 CD-1 s l a t e 5 .25 <0. 2 W1-1 greywacke 1 .82 <0.2 103 3.4.2 STATISTICAL ANALYSIS Hi s t o g r a m and p r o b a b i l i t y p l o t s of both a r i t h m e t i c and l o g 1 0 v a l u e s f o r a l l v a r i a b l e s were computer g e n e r a t e d . H i s t o g rams show lo g n o r m a l d i s t r i b u t i o n s f o r a l l elements except c o b a l t . F o l l o w i n g the p r o c e d u r e of S i n c l a i r (1976) the d a t a have been p a r t i o n e d g r a p h i c a l l y i n t o s e p a r a t e p o p u l a t i o n s . Three p o p u l a t i o n s are d e f i n e d f o r Pb, Ag, Cd and S; two f o r Zn, N i and Ba; and one f o r Co. Means, s t a n d a r d d e v i a t i o n s and t h r e s h o l d v a l u e s f o r the p a r t i o n e d p o p u l a t i o n s a r e p r e s e n t e d i n T a b l e 3-3. F i g u r e 3-8 shows the p r o b a b i l i t y p l o t f o r Ag. Three p o p u l a t i o n s a r e e v i d e n t . The upper p o p u l a t i o n (A) w i t h a t h r e s h o l d of 0.49 oz Ag/ton c o r r e s p o n d s t o e p i g e n e t i c m i n e r a l i z a t i o n . P o p u l a t i o n B ( t h r e s h o l d = 0.04 oz Ag/ton) has been d i v i d e d p e t r o g r a p h i c a l l y i n t o two s u b s e t s . B, i s c h a r a c t e r i z e d by s t r a t a b o u n d sedimentary s u l p h i d e s accompanied by r e m o b i l i z e d p o s s i b l y e p i g e n e t i c f e a t u r e s . B 2 c o r r e s p o n d s t o the s l a t e - b e l t which c o n t a i n s s t r a t a b o u n d s u l p h i d e s but l i t t l e e v i d e n c e of r e m o b i l i z a t i o n . The lower p o p u l a t i o n (C) r e p r e s e n t s the r e m a i n i n g (45) samples. The upper p o p u l a t i o n s f o r Pb, N i and Cd a l s o c o r r e s p o n d t o samples e x h i b i t i n g e p i g e n e t i c m i n e r a l i z a t i o n . The upper p o p u l a t i o n f o r z i n c c o r r e s p o n d s t o samples w i t h both e p i g e n e t i c and s t r a t a b o u n d ± r e m o b i l i z e d . s u l p h i d e t e x t u r e s . The upper p o p u l a t i o n of Ba r e p r e s e n t s s t r a t i f o r m o c c u r a n c e s . The p r o b a b i l i t y p l o t f o r S i n d i c a t e s t h r e e p o p u l a t i o n s which c o r r e s p o n d d i r e c t l y t o the amount of p y r i t e p r e s e n t . Upper 104 T a b l e 3-3 Means, s t a n d a r d d e v i a t i o n s and t h r e s h o l d 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 . Element P o p u l a t i o n s T h r e s h o l d s u n i t s _ % b 1 - b+s 2 b - s 3 Pb A ( . 0 6 ) 0 . 7 0 6 . 0 0 . 0 0 9 0 . 0 1 5 % B(.1S) 0 . 0 0 7 0 .01 0 . 0 0 4 9 0 . 0 0 5 5 0 . 0 0 3 3 C( . 79) O .i 0021 0 . 0 0 3 3 0 .0014 Zn A( .15) 0 . 45 0 . 8 0 0 . 2 5 0 . 0 5 % B( .85) 0 . ' 01 0 . 0 1 9 0 .0056 Ag A( .07) 0 . 94 1 .25 0 . 7 0 . 4 9 o / t B( .27) 0 . 10 0 . 2 0 0 . 0 4 8 0 . 0 4 0.02: C( .66) 0 . ' 01 0 . 0 2 0 .0052 C o 4 A( 1.0) 42 .0 56 .O 2 9 . 0 6 7 . 5 ppm Ni A( . 10) 440 .0 5 4 0 . 0 3 6 0 . 0 370 ppm 200 B( .90) 44 . 0 8 0 . 0 2 5 . 0 Ba A( .03) 1 .2 1 .35 1 . 10 0 . 6 5 % B( .97) 0 .07 0.21 0 . 0 2 5 Cd A( .08) 64 .0 8 0 . 0 5 0 . 0 38 ppm B( . 10) 18 .0 26 .0 13.0 8 . 5 C( . 82) 2 .3 4 . 2 1 .4 S A( .15) 9 .3 10. 3 6 . 2 2 .5 % B( . 6 5 ) 0 . 9 0 1 .4 0. 57 0. 35 c ( .20) 0 . 10 0 . 18 0 . 0 5 3 % of d a t a i n p o p u l a t i o n l a n t l l o g o f mean of lognorma) p o p u l a t i o n 2 a n t l l o g of mean p l u s one s t a n d a r d d e v i a t i o n of lognormal p o p u l a t i o n 3ant11og of mean minus one s t a n d a r d d e v i a t i o n of lognormal p o p u l a t i o n 4normal d i s t r i b u t i o n 105 0.001 ' -| r-^ 1 - i 1 1 1 1 1 1 1 1 2 10 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 9 5 9 8 Cumulative Percent F i g u r e 3-8. P r o b a b i l i t y graph for 69 Ag values from sedimentary and v o l c a n i c rocks in the Sandon area, Slocan mining camp. Black dots are o r i g i n a l data, open c i r c l e s are estimated p a r t i t i o n i n g p o i n t s . Three p o p u l a t i o n s are e v i d e n t , p o p u l a t i o n 'B' can be s u b d i v i d e d i n t o B, and B 2 on b a s i s of h a b i t of s u l p h i d e occurrence. 106 p o p u l a t i o n samples a r e r e p r e s e n t e d e q u a l l y of s t r a t i f o r m ± r e m o b i l i z e d , s t r a t i f o r m s l a t e - b e l t and l e s s abundant e p i g e n e t i c type s u l p h i d e t e x t u r e s . T a b l e 3-4 compares mean me t a l abundances of S l o c a n Group l i t h o l o g i c u n i t s , R o s s l a n d Group, N e l s o n p l u t o n i c s and average s h a l e v a l u e s . Of t h e s e , the s l a t e b e l t (n = 11) shows the most s i g n i f i c a n t v a r i a t i o n and enrichment i n Ag, Ba and S r e l a t i v e t o average s h a l e (Vine and T o u r t e l o t , 1970). S u l p h u r v a l u e s show a l a r g e v a r i a b i l i t y , a r e h i g h r e l a t i v e t o o t h e r u n i t s and c l e a r l y c o r r e l a t e w i t h the amount of p y r i t e (Appendix C ) . Mean s l a t e b e l t Ba v a l u e s a r e e n r i c h e d by a f a c t o r of 10 over average s h a l e s and i n t e r e s t i n g l y e q u a l the mean of m i n e r a l i z e d samples (n = 13, T a b l e 3-1). S i l v e r i s e q u a l l y e n r i c h e d i n ' U n i t - 1 ' , a l t h o u g h t h i s might be an a r t i f a c t of the s m a l l data s e t . V a r i a t i o n of the Co and N i abundances a r e g r e a t e r w i t h i n i n d i v i d u a l ' l i t h o l o g i c u n i t s ' than f o r comparisons among u n i t s . In comparison w i t h m i n e r a l i z e d r o c k s t h i s g e n e r a l i z a t i o n i s t r u e f o r Co, but not N i . M i n e r a l i z e d r o c k s ( u n d i v i d e d as t o l i t h o l o g y ) a r e e n r i c h e d i n n i c k e l by an o r d e r of magnitude over u n m i n e r a l i z e d r o c k . C o b a l t ( % ) / n i c k e l ( % ) r a t i o s a l s o i n d i c a t e t h i s e n r i c h m e n t . Co/Ni ( c a l c u l a t e d from means) f o r the S l o c a n sediments v a r y from 0.5 t o 0.95, a r e 0.84 f o r the R o s s l a n d but a r e 0.15 f o r e p i g e n e t i c m i n e r a l i z e d r o c k s . Table 3-4 Means for Slocan regional rock geochemistry. Comparislons with other studies and average shales. ELEMENT II ^ it n=2 •i 2 " n=13 LITHOLOGIC UNITS SLOCAN GROUP "2" Slate belt "3" n=201 n=11 n=9 "3" n=631 ROSSLAND GROUP n=21 NELSON BATHOLITH n=191 BLACK SHALE 2 Pb ppm 14 24 32 31 25 31 19 33 20 Zn ppm 62 129 58 125 156 175 98 101 <300 Ag o/t .066 .018 n. c. .057 .015 n.c. .007 n.c. <0.029 Co ppm 15 43 n.c. 32 38 n.c. • 47 n.c. 10 Ni ppm 30 44 n.c. 63 43 n.c. 56 n.c. 50 Ba % .096 .052 n.c. .333 .054 n.c. .0066 n.c. .030 Cd ppm 1 .6 2.8 n.c. 3.7 3.4 n.c. 1.9 n.c. n.c. S % 1.13 1.14 n.c. 4.94 1.11 n.c. 0.71 n.c. n.c. 1 Cox (1979) 2 Vine and Tourtelot (1970) 108 3.4.3 TRIANGULAR PLOTS Four p o l y m e t a l l i c v e i n camps from s o u t h e a s t e r n B r i t i s h C o lumbia, have been c h a r a c t e r i z e d u s i n g t r i a n g u l a r p l o t s ( G o l d s m i t h and S i n c l a i r , 1984). One of t h e s e i s the S l o c a n camp. For the S l o c a n , p r o d u c t i o n p l o t s of s i l v e r - l e a d - z i n c b e s t d e s c r i b e the v e i n m i n e r a l o g y of the camp. These t h r e e v a r i a b l e s a l s o p e r m i t comparison w i t h rock g e o c h e m i c a l data i n the p r e s e n t s t u d y . V a r i o u s o t h e r c o m b i n a t i o n s of the geo c h e m i c a l d a t a were p l o t t e d . The most u s e f u l t r i a n g u l a r p l o t s f o r e s t a b l i s h i n g m e t a l r a t i o v a r i a t i o n s c o r r e s p o n d i n g t o d i f f e r e n t l i t h o l o g i c u n i t s a r e Ag-Pb-Zn, Pb-Ni-Co and Ag-Ni-Co. F i g u r e 3-9a shows average p r o d u c t i o n f i g u r e s p l o t t e d f o r 128 v e i n d e p o s i t s from the S l o c a n camp (from G o l d s m i t h and S i n c l a i r , 1984). S i l v e r ( o z ) / l e a d ( % ) r a t i o s f o r the d e p o s i t s a r e g r e a t e r than 0.7. A group of z i n c - r i c h d e p o s i t s c l u s t e r w i t h i n t h i s h i g h Ag/Pb f i e l d c l o s e t o the z i n c v e r t e x w i t h P b ( % ) / Z n ( % ) r a t i o s of l e s s than 0.25. The r e m a i n i n g d e p o s i t s have Pb/Zn g r e a t e r than 0.7. In c o m p a r i s i o n , F i g u r e 3-9b shows the A g ( o z ) - P b ( % ) - Z n ( % ) p l o t of rock g e o c h e m i s t r y . The most o b v i o u s d i f f e r e n c e between F i g u r e 3-9a and 3-9b i s the d e p l e t e d n a t u r e of the sediments i n r e g a r d t o l e a d . S i l v e r ( o z ) / l e a d ( % ) r a t i o s a r e g r e a t e r than 2.5 and l e a d ( % ) / z i n c ( % ) r a t i o s l e s s than 1.0. T h i s r e s t r i c t s the d a t a t o l e s s than h a l f the Ag-Pb-Zn p l o t a r e a . Symbols i n F i g u r e 3-9b s e p a r a t e l i t h o l o g i c u n i t s , e p i g e n e t i c m i n e r a l i z a t i o n and i n d i c a t e h i g h e r r e l a t i v e s i l v e r f o r the 109 Ag oz/ ton • 1 1 1 1 1 1 1 1 i Pb % Zn % Figure 3-9. Ag-Pb-Zn Triangular p l o t s . A: average production grades Slocan mining camp, (Goldsmith and S i n c l a i r , 1984). B: regional geochemistry, Slocan mining camp. S o l i d squares denote Slocan unit-1, open squares for unit-2, s o l i d c i r c l e s for s l a t e b e l t and open c i r c l e s for unit-3. T r i a n g l e s represent Rossland Group and diamonds denote m i n e r a l i z a t i o n . 1 10 s l a t e - b e l t d a t a . A c l u s t e r of m i n e r a l i z e d samples near th e z i n c v e r t e x c o r r e s p o n d s t o the z i n c - r i c h d e p o s i t s of F i g u r e 3-9a. The r e m a i n i n g m i n e r a l i z e d samples (except two) s p r e a d out c l o s e t o the Ag-Zn l i n e due t o low r e l a t i v e Pb abundances. S i l v e r ( o z / t o n ) - n i c k e l ( % ) - c o b a l t ( % ) p l o t ( F i g . 3-10a) shows da t a d i s t r i b u t i o n e x t e n d i n g outward from the Ag v e r t e x about the 1:1 C o ( % ) / N i ( % ) r a t i o l i n e . M i n e r a l i z e d samples c l u s t e r near, the Ag v e r t e x and e x t e n d a l o n g the Ag-Ni l i n e s u g g e s t i v e of an enrichment of N i over Co. S l a t e - b e l t d a t a p l o t s c l o s e s t t o the Ag v e r t e x . D i s t r i b u t i o n of samples about the 1:1 Co/Ni l i n e suggest a s y m p a t h e t i c v a r i a t i o n f o r the two. L e a d ( % ) - n i c k e l ( % ) - c o b a l t ( % ) p l o t ( F i g . 3-l0b) shows two s e p a r a t e c l u s t e r s of e p i g e n e t i c m i n e r a l i z a t i o n . These a r e s i t u a t e d near the l e a d and n i c k e l v e r t i c e s r e s p e c t i v e l y . U n m i n e r a l i z e d samples c l u s t e r about the 1:1 Co/Ni l i n e i n the c e n t e r of the diagram as i n F i g u r e 3-10a. 3.5 DISCUSSION Three main s t a g e s of s u l p h i d e f o r m a t i o n have been d e f i n e d f o r the sediments on the b a s i s of t e x t u r e . The i n c r e a s e d abundance of Cu, N i , Zn, and P b - s u l p h i d e s f o r each subsequent s t a g e of s u l p h i d e f o r m a t i o n ( i . e . h y d r o t h e r m a l > metamorphic > d i a g e n i c ) i s c o m p a t i b l e w i t h the degree of i n t r o d u c t i o n of base metal s u l p h i d e s t o the sediment. The t o t a l abundance of t r a c e m e t a l s i s assumed t o remain 111 A g o z / t o n a) Rock Geochemistry (n - 69) F i g u r e 3-10. Ag-Ni-Co and Pb-Ni-Co T r i a n g u l a r p l o t s of r e g i o n a l rock g e o c h e m i s t r y , from Sandon a r e a , S l o c a n m i n i n g camp. Symbols as d e s c r i b e d i n F i g u r e 3-9. 1 1 2 unchanged d u r i n g m o b i l i z a t i o n / l o c a l l i z a t i o n w i t h i n the sediment ( i . e . d u r i n g d i a g e n e s i s ) . Trace m e t a l d i s t r i b u t i o n w i t h i n the sediment i s as i m p o r t a n t as t o t a l c o n c e n t r a t i o n i n a s s e s s i n g whether the sediment is/was c a p a b l e of r e l e a s i n g m e t a l s t o m i n e r a l i z i n g s o l u t i o n s . A n a l y s i s of o r g a n i c m a t t e r from carbonaceous mudstones h o s t i n g the XY d e p o s i t a t Howards P a s s , Yukon -N.W.T. boundary i n d i c a t e t h a t l e s s than 22% of Cu, N i , Co, Zn and Ag i s bound i n the o r g a n i c s , and t h a t t h e b u l k of t r a c e m e t a l s occur w i t h i n the s u l p h i d e s ( G o o d f e l l o w et al. , 1983). Trace elements i n p y r i t e s e p a r a t e s from B l a c k Sea carbonaceous sediments ( B u l u z a r a , 1969, r e f e r r e d t o i n G o o d f e l l o w et al. , 1983) and b l a c k s h a l e s from Amjhore, I n d i a ( P a n d a l a i et al. , 1983) show t h a t most of the Ag, Cu, 2 + Pb, Co, and N i a r e i n c o r p o r a t e d i n i r o n s u l p h i d e s , the (Co 2+ 2 + and N i s u b s t i t u t e i s o m o r p h o u s l y f o r Fe i n t h e p y r i t e l a t t i c e owing t o s i m i l i a r i o n i c r a d i i , o t h e r elements p r o b a b l y o c c u r as d i s c r e t e s u l p h i d e p h a s e s ) . R e f l e c t e d l i g h t m i c r o s c o p y combined w i t h s c a n n i n g e l e c t r o n m i c r o s c o p e - e n e r g y d i s p e r s i v e s p e c t r o s c o p e s t u d i e s of the S l o c a n sediments i n d i c a 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 , m i l l e r i t e and g a l e n a i n p y r i t e , and l e s s o f t e n , i n p y r r h o t i t e . D i s c r e t e s i l v e r s u l p h i d e m i n e r a l s c o u l d not be i d e n t i f i e d i n the s ediments. B o y l e (1968) has emphasized t h a t f o r Ag, the degree of d i a g e n e s i s and metamorphism d e t e r m i n e s t r a c e m e t a l l o c a t i o n . Where o n l y s l i g h t l y metamorphosed the t r a c e m e t a l s a r e 1 13 a s s o c i a t e d w i t h c l a y s , carbonaceous s u b s t a n c e s (bitumen, humic and f l u v i c a c i d s ) and f i n e g r a i n e d n e a r l y c o l l o i d a l s u l p h i d e s ( B o l y e , 1968). I n c r e a s e d metamorphism causes l o c a l l i z a t i o n of t r a c e m e t a l s , commonly found as i n c l u s i o n s w i t h i n i r o n s u l p h i d e s . In the S l o c a n sediments p y r r h o t i t e i s s p a t i a l l y a s s o c i a t e d i n h o r n f e l s a u r e o l e s around i n t r u s i v e b o d i e s . T h i s s u g gests r e g i o n a l / c o n t a c t metamorphism of p y r i t i c sediments has r e l e a s e d S d u r i n g the c o n v e r s i o n p y r i t e t d p y r r h o t i t e . S u l p h u r i s o t o p e s t u d i e s of v e i n m i n e r a l s d e f i n e a 8 3 a S sprea d of -11.0% t o -1.0, a v e r a g i n g -7.0 (Brame, 1979). These v a l u e s a r e c h a r a c t e r i s t i c of s e d i m e n t a r y s u l p h i d e s u l p h u r and s u p p o r t a sediment s u l p h u r s o u r c e . D u r i n g replacement ( p y r i t e t o p y r r h o t i t e ) or s i m p l e r e c r y s t a l l i z a t i o n , the i m p u r i t i e s ( i . e . t r a c e m e t a l s and s u l p h i d e i n c l u s i o n s ) d i s s o c i a t e and m i g r a t e t o the c r y s t a l edge where, p r e c i p i t a t i o n or d i s s o l u t i o n o c c u r s depending upon the ambient t e m p e r a t u r e , p r e s s u r e and c h e m i c a l a c t i v i t i e s . The s o l u b i l i t i e s of most s u l p h i d e s a r e g r e a t e s t i n the b i s u l p h i d e (HS") s t a b i l i t y r e g i o n ( F y f e et al. , 1978) and s u l p h u r r e l e a s e d d u r i n g metamorphism would i n c r e a s e the a c t i v i t i e s of the aqueous S - s p e c i e s . S u l p h i d e c o m p l e x i n g of Ag, Pb, Zn and Cu are more s t a b l e than c h l o r i d e complexes i n t h e t emperature range suggested by f l u i d i n c l u s i o n s , ( R e i n s b a k k e n , 1968) f o r v e i n f o r m a t i o n . C h l o r i d e complexes a r e more s t a b l e f o r Ag above 300°C and f o r Pb below 300°C (Bar n e s , 1979). The p a r a g e n e t i c s e q u e n c e / m i n e r a l o g i c z o n a l p a t t e r n f o r l o d e d e p o s i t s , r e s u l t s from c h a n g i n g ; s o l u t i o n 1 14 c h e m i s t r y s (pH, Eh, s u l p h u r a c t i v i t y ) , t e m p e r a t u r e s , and p r e s s u r e s d u r i n g v e i n d e p o s i t i o n . G e n e r a l p a r a g e n e t i c sequence of ore d e p o s i t i o n i s p y r i t e - s p h a l e r i t e - t e t r a h e d r i t e - g a l e n a - s i l v e r s u l p h o s a l t s and n a t i v e s i l v e r ( C a i r n e s , 1934). The age of m i n e r a l i z a t i o n i s g e n e r a l l y b e l i e v e d t o be r e l a t e d t o i n t r u s i o n and t h e r e f o r e e q u i v a l e n t i n age t o the N e l s o n b a t h o l i t h (Reynolds and S i n c l a i r , 1971; Andrew et al. , 1985). Metamorphogenic h y d r o t h e r m a l f l u i d s e i t h e r g e n e r a t e d or m o d i f i e d through a d d i t i o n s d u r i n g c o n t a c t metamorphism by i n t r u s i o n of the N e l s o n b a t h o l i t h were l i k e l y s u l p h i d e - r i c h s o l u t i o n s . The r e l e a s e . o f S, the h i g h s o l u b i l i t i e s f o r Pb-, Zn- and C u - s u l p h i d e complexes c o i n c i d e n t i n time w i t h the i n i t i a l m i n e r a l i z i n g f l u i d s i s c o m p a t i b l e w i t h v e i n p a r a g e n e s i s . F l u i d i n c l u s i o n s t u d i e s (12 d e p o s i t s ) suggest t h a t ore f l u i d s were r a t h e r d i l u t e b r i n e s , s a l i n i t i e s b e i n g too low t o p r e c i p i t a t e daughter c r y s t a l s a t 25°C (<26.4 wt % N a C l : R e i n s b a k k e n , 1968). F l u i d i n c l u s i o n s from the S c r a n t o n d e p o s i t c o n t a i n daughter c r y s t a l s , and up t o 40 NaCl e q u i v a l e n t % s a l i n i t y (Brame, 1979). S a l i n e s o l u t i o n s such as these a r e c a p a b l e of t r a n s p o r t i n g Pb and Ag as c h l o r i d e complexes. Assuming p r e c i p i t a t i o n from d e c r e a s i n g f l u i d t e m p e r a t u r e s , l a t e s t a g e s i l v e r d e p o s i t i o n s u g gests changing from an i n i t i a l C l ~ dominated hot b r i n e t o a l e s s s a l i n e HS" r i c h system. F a c t o r s such a s : d e c r e a s i n g temperature of f l u i d s , of the b a t h o l i t h , or the ambient t e m p e r a t u r e ; l o n g e r p a t h l i n e s f o r f l u i d c i r c u l a t i o n t h a t f a c i l i t a t e more 1 15 thorough sediment b u f f e r i n g of s o l u t i o n s ; d e c r e a s e i n a c t i v i t y of s p e c i f i c c h e m i c a l s p e c i e s such as S c o u l d produce t h i s change i n s o l u t i o n c h e m i s t r y . Flow r a t e v s . r e a c t i o n r a t e , d e t e r m i n e s whether the w a l l r o c k can b u f f e r f l u i d c o m p o s i t i o n s . I f the f l o w r a t e i s g r e a t e r than the r e a c t i o n r a t e , d i s e q u i l i b r i u m mass t r a n s p o r t r e s u l t s ( F y f e et al . , 1 978). T h i s c h a r a c t e r i z e s c o n d i t i o n s of n e a r - s u r f a c e v e i n f o r m a t i o n . The l a c k of w a l l r o c k a l t e r a t i o n and the f a c t t h a t the m i n e r a l i z a t i o n o c c u p i e s l a r g e c o n t i n u o u s t h r o u g h - g o i n g s t r u c t u r e s s u g g e s t s t h a t t e m p e r a t u r e i s the f a c t o r c o n t r o l l i n g p r e c i p i t a t i o n . T h r o t t l i n g o r b o i l i n g can p r o v i d e a p r e s s u r e d e c rease r e s u l t i n g i n d e p o s i t i o n but f l u i d i n c l u s i o n s t u d i e s ( R e i n s b a k k e n , 1968) show no e v i d e n c e f o r f l u i d b o i l i n g . C o m p a r i s i o n s between l i t h o l o g i c a l u n i t s of the S l o c a n and R o s s l a n d Groups i n d i c a t e e n r i c h m e n t s of Ag, Ba and S c o n c e n t r a t i o n s f o r o n l y the S l a t e b e l t ( F i g . 3-11). T h i s n o r t h w e s t e r l y t r e n d i n g zone c o i n c i d e s s p a t i a l l y w i t h q u a d r a t i c t r e n d s e s t a b l i s h e d f o r t r a c e i n c l u s i o n s of Ag i n g a l e n a , Sn i n s p h a l e r i t e and As i n p y r i t e ( S i n c l a i r , 1967). S i n c l a i r (1967) su g g e s t s the d i s t r i b u t i o n p a t t e r n of t r e n d s r e f l e c t s a temperature g r a d i e n t w i t h the r e l a t i v e l y h i g h t e m p e r a t u r e c e n t e r l o c a t e d a t Sandon. S u l p h i d e t e x t u r e s e s t a b l i s h the s y n / d i a g e n e t i c n a t u r e of the S l a t e b e l t s u l p h i d e s . The c o i n c i d e n c e of h i g h metal c o n c e n t r a t i o n s l o c a t e d c e n t r a l l y t o the h i g h e s t s p a t i a l d e n s i t y d i s t r i b u t i o n of d e p o s i t s and tho s e w i t h r e l a t i v e l y more Ag Rossland Grp. (undivided) r "3" -•= 3 " s l a t e . ° 2 belt" C CO eg o *9" -•—r~ 1.1 —i 1— 1.3 1.5 (ppm) i 1.7 -i 1 1 — i i i r 1.6 2.0 2.4 0.6 1.0 1.4 1.8 2.2 (ppm) (oz/t) Rossland Grp (undivided) (ppm) i i 1 1— 1.0 1.6 2.2 2.8 (%) 1 C d —i 1 1 0.8 1.4 2.0 (ppm) - I -0.6 1.0 1.4 F i g u r e 3 - 1 1 . V a r i a t i o n i n means and 68 p e r c e n t i l e s of t r a c e element c o n c e n t r a t i o n s f o r i n f e r r e d s t r a t i g r a p h i c s e c t i o n . Data from Table 3 - 1 . S l a t e b e l t Ag and Ba c o n c e n t r a t i o n s are d i s t i n c t l y h i g h . High Ag and low Pb, Zn, and Co co n c e n t r a t i o n s are unique to u n i t - 1 . Mean and standard d e v i a t i o n values are: Log(lO x c o n c e n t r a t i o n ) f o r Cd, a r i t h m e t i c f o r Co, and Log c o n c e n t r a t i o n f o r the other elements. 1 1 7 s u g g e s t s t h i s u n i t may have a c t e d as a source f o r v e i n m e t a l s . Carbonaceous h o r i z o n s of the S l a t e b e l t a r e e n r i c h e d i n t r a c e m e t a l s but r e c o g n i z a b l e c r y s t a l s o t h e r than p y r i t e a r e not common. The abundance of s u l p h i d e s i n modern sediments has been shown t o be d i r e c t l y p r o p o r t i o n a l t o the o r g a n i c c o n t e n t of the sediments ( B e r n e r , 1970). A mean v a l u e of 4.2% t o t a l carbon (n = 5) p l a c e s the s l a t e b e l t r o c k s i n the b l a c k s h a l e c a t e g o r y of V i n e and T o u r t e l o t (1970). These may r e p r e s e n t 'metal s i n k s ' where m e t a l s have been t r a p p e d i n nonmobile o r g a n i c or s u l p h i d e phases (Hanor, 1979) r a t h e r than l i k e l y s o u r c e beds. The m e a n i n g f u l n e s s of comparing a b s o l u t e m e t a l abundances f o r samples which c o n t a i n v a r i a b l e amounts of carbonaceous m a t e r i a l and p y r i t e i s u n c e r t a i n . T r i a n g u l a r diagrams d i s p l a y d a t a as r e l a t i v e amounts and thus p r o v i d e a means t o a s s e s s m e t a l r a t i o s . Ag-Pb-Zn p l o t s f o r sediment rock g e o c h e m i s t r y show the S l a t e b e l t d a t a as c o n t a i n i n g h i g h e r r e l a t i v e s i l v e r . The sediment g e o c h e m i c a l d a t a ( i n p a r t i c u l a r , m e t a l r a t i o s ) , d i f f e r from average p r o d u c t i o n f i g u r e s f o r the camp o n l y i n the r e l a t i v e amount of Pb. The sediments a r e d e p l e t e d i n r e l a t i o n t o the v e i n s . A g e n e t i c model i n v o l v i n g a s e d i m e n t a r y s o u r c e would r e q u i r e s u b s t a n t i a l p r e f e r e n t i a l enrichment of Pb i n v e i n s r e l a t i v e t o the amounts found i n the s e d i m e n t s . Source rock volumes can be d e t e r m i n e d u s i n g t o t a l p r o d u c t i o n f i g u r e s from the S l o c a n m i n i n g camp ( G o l d s m i t h , 1985) t o t e s t the p l a u s i b i l i t y of sediment d e r i v a t i o n f o r 118 v e i n Ag, Pb and Zn. The f o l l o w i n g c a l c u l a t i o n s use mean S l a t e b e l t m e t a l v a l u e s (Table 3-4) and assume 10% e x t r a c t i o n from the source r o c k . For Ag, t o t a l p r o d u c t i o n of 64 x 10 6 o z / .0002% x 10% ( e x t r a c t i o n ) = 3.4 x 1 0 1 2 o z / 35200 oz/tonne or 0.10 x 10 9 tonnes of rock i . e . 0.10 x 10 9 tonnes / 2.7 tonne/m 3 = 3.7 x I 0 7 m 3 . R e c a l c u l a t i n g u s i n g the mean S l o c a n v a l u e f o r Ag (0.00007%) r e s u l t s i n 8.2 x I0 8 m 3 . C a l c u l a t i o n s f o r Pb, t o t a l p r o d u c t i o n of 0.22 x 10 6 tonne r e q u i r e s 2.7 x I0 8m 3 and f o r Zn, t o t a l p r o d u c t i o n of 0.24 x 10 s tonne, 7.0 x I 0 7 m 3 of sour c e rock a re r e q u i r e d . In c o m p a r i s i o n , source rock volumes f o r Ag are a p p r o x i m a t e l y e q u a l t o tho s e f o r Pb u s i n g mean sediment v a l u e s . Source rock volume f o r Zn a r e s l i g h t l y l e s s . From t h e s e c a l c u l a t i o n s a sedi m e n t a r y s o u r c e seems a v i a b l e p o s s i b i l i t y f o r Ag, Pb and Zn. 3.6 CONCLUSION Three main s t a g e s of s u l p h i d e f o r m a t i o n have been d e f i n e d f o r the sediments. S t r a t i f o r m , i n t e r p r e t e d as s y n / d i a g e n e t i c p y r i t e , s p h a l e r i t e , c h a l c o p y r i t e y m i l l e r i t e and g a l e n a ( d e c r e a s i n g o r d e r of abundance) have been i d e n t i f i e d from v a r i o u s l i t h o l o g i c a l h o r i z o n s i n the S l o c a n s e d i m e n t s . S i l v e r m i n e r a l s were not i d e n t i f i e d a l t h o u g h s u b s t a n t i a l l y h i g h e r Ag than average s h a l e v a l u e s a re i n d i c a t e d f o r u n i t s w i t h no i n d i c a t i o n of e p i g e n e t i c m i n e r a l i z a t i o n . F e - s u l p h i d e s and t r a c e metal d i s t r i b u t i o n and abundances suggest t h a t c o n t a c t and r e g i o n a l 119 metamorphism i n i t i a t e d r e l e a s e of S t o metamorphic f l u i d s . T e x t u r a l s t u d i e s i n d i c a t e t h a t t r a c e m e t a l m o b i l i z a t i o n i n c r e a s e s r e l a t i v e t o the amount of metamorphism. L i t h o l o g i c / s t r a t i g r a p h i c g e o c h e m i s t r y has d e f i n e d a s i n g l e u n i t / z o n e from the S l o c a n Group which i s e n r i c h e d i n Ag, Ba and S. Out c r o p d i s t r i b u t i o n of the S l a t e b e l t c o i n c i d e s w i t h the h i g h e s t s p a t i a l d e n s i t y d i s t r i b u t i o n of v e i n d e p o s i t s and c o u l d r e p r e s e n t a sou r c e f o r v e i n d e p o s i t s . C a l c u l a t e d s o u r c e rock volumes r e q u i r e d t o mass b a l a n c e t o t a l p r o d u c t i o n f i g u r e s w i t h mean sediment m e t a l abundance i n d i c a t e t h a t a s e d i m e n t a r y s o u r c e f o r v e i n Ag, Pb and Zn i s r e a s o n a b l e even a t mean S l o c a n sediment v a l u e s . REFERENCES CITED Andrew, A., Godwin, C . I . and S i n c l a i r , A . J . 1984. M i x i n g l i n e i s o c h r o n s : a new i n t e r p r e t a t i o n of g a l e n a l e a d i s o t o p e d a t a from s o u t h e a s t e r n B r i t i s h C olumbia. Economic Geology, 79, pp. 919-932. A r c h i b a l d , D. A., Krogh, T. E., Armstrong, R. L. and F a r r a r , E. 1984. Geochronology and t e c t o n i c i m p l i c a t i o n s of magmatism and metamorphism, s o u t h e r n Kootenay Arc and n e i g h b o u r i n g r e g i o n s , s o u t h e a s t e r n B r i t i s h C olumbia. P a r t I I : M i d - C r e t a c e o u s t o Eocene. Canadian J o u r n a l of E a r t h S c i e n c e s , 21, pp. 567-583. B a r n e s , H. L. 1979. S o l u b i l i t i e s of ore m i n e r a l s , i n Barnes, H. L., ed., G e o c h e m i s t r y of h y d r o t h e r m a l . o r e d e p o s i t s . New York, John W i l e y and Sons, pp. 404-460. B e r n e r , R. A. 1969. M i g r a t i o n of i r o n and s u l p h u r w i t h i n a n a e r o b i c sediments d u r i n g e a r l y d i a g e n e s i s . American J o u r n a l of S c i e n c e , 267, pp. 19-42. B e r n e r , R. A. 1970. P l e i s t o c e n e sea l e v e l s p o s s i b l y i n d i c a t e d by b u r i e d b l a c k sediments i n the B l a c k Sea. N a t u r e , 227, p. 700. B o y l e , R. W. 1968. The g e o c h e m i s t r y of s i l v e r and i t s d e p o s i t s . G e o l o g i c a l Survey of Canada, B u l l e t i n 160, 264 P-Brame, S. 1979. M i n e r a l i z a t i o n near the n o r t h e a s t e r n margin of the N e l s o n b a t h o l i t h . U n p u b l i s h e d MSc. t h e s i s U n i v e r s i t y of A l b e r t a , Edm., 146 p. B u l u g a r a , G. Yu. 1969. M i n e r a l o g y and g e o c h e m i s t r y of i r o n s u l p h i d e s i n B l a c k Sea s e d i m e n t s . L i t o l . P o l e z . I s k o p . , 4, pp. 3-16. C a i r n e s , C. E. 1934. S l o c a n m i n i n g camp, B r i t i s h C o lumbia. G e o l o g i c a l Survey of Canada, Memoir 173, 137 p. Cox, J . 1979. The geology of the northwest margin of the N e l s o n b a t h o l i t h , B r i t i s h Columbia. M.Sc. t h e s i s , U n i v e r s i t y of A l b e r t a , Edm., 95 p. E t h e r i d g e , M. A., W a l l , V. J . and Cox, S. F. 1984. H i g h f l u i d p r e s s u r e s d u r i n g r e g i o n a l metamorphism and d e f o r m a t i o n : i m p l i c a t i o n s f o r mass t r a n s p o r t and d e f o r m a t i o n mechanisms. J o u r n a l of G e o p h y s i c a l Research 89, B6, pp. 4344-4358. F y f e , W. S., P r i c e , N. J . and Thompson, A.B. 1978. F l u i d s i n the e a r t h ' s c r u s t , Developments i n G e o c h e m i s t r y 1. 120 121 E l s e v i e r , Amsterdam, 383 p. G o l d s m i t h , L. B. 1984. A q u a n t i t a t i v e a n a l y s i s of some v e i n - t y p e m i n e r a l d e p o s i t s i n s o u t h e r n B r i t i s h Columbia. M.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h C o lumbia, Van., 86 P-G o l d s m i t h , L. B. and S i n c l a i r , A. J . 1984. T r i a n g u l a r graphs as an a i d t o m e t a l l o g e n i c s t u d i e s of p o l y m e t a l l i c v e i n d e p o s i t s . B r i t i s h Columbia M i n i s t r y of Enery, Mines and P e t r o l e u m R e s o u r c e s , G e o l o g i c a l F i e l d w o r k , 1983, Paper 1984-1, pp. 240-245. G o o d f e l l o w , W. D., Jo n a s s o n , I . R. and M o r g a n t i , J . M. 1983. Z o n a t i o n of c h a l c o p h i l e elements about the Howards' Pass (XY) Zn-Pb d e p o s i t , Selwyn B a s i n , Yukon. J o u r n a l of Geochemical E x p l o r a t i o n , 19, pp. 503-542. Hanor, J . S. 1979. The se d i m e n t a r y g e n e s i s of h y d r o t h e r m a l f l u i d s , i n Barnes, H. L., ed., Geoche m i s t r y of h y d r o t h e r m a l ore d e p o s i t s . New York, John W i l e y and Sons, pp. 137-172. L e t t , R. E. W. and F l e t c h e r , W. K. 1979. The secondary • d i s p e r s i o n of t r a n s i t i o n m e t a l s through a c o p p e r - r i c h h i l l - s l o p e bog i n the Cascade M o u n t a i n s , B r i t i s h C o l u m b i a . I n t e r n a t i o n a l Geochemical E x p l o r a t i o n Symposium, P r o c e e d i n g s No. 7, pp. 103-115. Logan, J . M. 1986. B r i t i s h Columbia M i n i s t r y of Energy, Mines and P e t r o l e u m R e s o u r c e s , G e o l o g i c a l F i e l d w o r k , 1985, Paper 1986-1, pp. 288-301. Marmo, V. 1960. On the p o s s i b l e g e n e t i c r e l a t i o n s h i p between s u l p h i d e s c h i s t s and o r e s . XXI I n t e r n a t i o n a l G e o l o g i c a l C o n g r e s s . P a r t XVI, Copenhagen, pp. 160-163. McKibben, M. A. and E l d e r s , W. A. 1985. Fe-Zn-Cu-Pb m i n e r a l i z a t i o n i n the S a l t o n Sea geothermal system, I m p e r i a l V a l l e y , C a l i f o r n i a . Economic Geology, 80, pp. 539-559. O r r , J . F. W. 1971. M i n e r a l o g y and c o m p u t e r - o r i e n t e d study of m i n e r a l d e p o s i t s i n S l o c a n C i t y camp, N e l s o n m i n i n g d i v i s i o n , B r i t i s h Columbia. M.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h C olumbia, Van., 143 p. P a n d a l a i , H. S., Majumder, T. and Chandra, D. 1983. Geo c h e m i s t r y of p y r i t e and b l a c k s h a l e s of Amjhore, Rahtas D i s t r i c t , B i h a r , I n d i a . Economic Geology, 78, pp. 1505-1513. R e i n s b a k k e n , A. 1968. F l u i d i n c l u s i o n s t u d i e s of gangue m i n e r a l s from the S l o c a n m i n i n g d i s t r i c t , B r i t i s h 1 22 Columbia. B.Sc. t h e s i s , U n i v e r s i t y of B r i t i s h Columbia. Van., 73 p. R i c k a r d , D. T. 1973. L i m i t i n g c o n d i t i o n s f o r sy n s e d i m e n t a r y s u l p h i d e ore f o r m a t i o n . Economic Geology, 68, pp. 605-617. R o b i n s o n , M. C. c i r c a 1952. G e o l o g i c a l s e t t i n g and r e l a t i o n s h i p s of the s i l v e r - l e a d - z i n c ore d e p o s i t s of the S i l v e r t o n a r e a , S l o c a n m i n i n g camp. U n p u b l i s h e d S i n c l a i r , A. J . 1967. Trend s u r f a c e a n a l y s i s of minor elements i n s u l p h i d e s of the S l o c a n m i n i n g camp, B r i t i s h C o lumbia, Canada. Economic Geology, 62, pp. 1095-1101. S i n c l a i r , A. J . 1976. A p p l i c a t i o n of p r o b a b i l i t y i n m i n e r a l e x p l o r a t i o n . S p e c i a l Volume Number 4, A s s o c i a t i o n of E x p l o r a t i o n Geochemists, Richmond, B r i t i s h Columbia, 95 P. S t a n t o n , R. L. 1964. M i n e r a l i n t e r f a c e s i n s t r a t i f o r m o r e s . T r a n s a c t i o n s of I n s t i t u t e of M i n i n g and M e t a l l u r g y , 7 4 ( 2 ) , pp. 45-79. Sweeney, R. E. and K a p l a n , I . R. 1973. P y r i t e f r a m b o i d f o r m a t i o n ; l a b o r a t o r y s y n t h e s i s and marine sediments. Economic Geology, 68, pp. 618-634. T i k h o m i r o v a , Ye. S. 1960. The problem of geochemical m o b i l i t y of elements d u r i n g t h e f o r m a t i o n of s u l p h i d e c o n c e n t r a t i o n s i n s h a l e - b e a r i n g d e p o s i t s of the v o l g a and b a l t i c b a s i n s . G e o c h e m i s t r y , pp. 1098-1100. V i n e , J . D. and T o u r t e l o t , E. B. 1970. Geochemistry of b l a c k s h a l e d e p o s i t s a summary r e p o r t . Economic Geology, 65, pp. 253-272. 4. LEAD ISOTOPE ABUNDANCES IN LAYERED SULPHIDES WITHIN THE  SLOCAN GROUP AND THEIR BEARING ON GENESIS OF AG-PB-ZN-AU VEINS 4.1 INTRODUCTION Most e a r l y s t u d i e s of the S l o c a n m i n i n g camp imply a g e n e t i c r e l a t i o n s h i p between the m i n e r a l d e p o s i t s and the N e l s o n p l u t o n i c r o c k s ( C a i r n e s , 1934; Hedley, 1952; L i t t l e , 1960). A l t e r n a t i v e l y , F y l e s (1967) m a i n t a i n s t h e r e i s n e i t h e r r e g i o n a l z o n i n g nor g e o l o g i c e v i d e n c e t h a t r e l a t e s the b a t h o l i t h t o any of the d e p o s i t s . In u n d e r s t a n d i n g g e n e s i s of an ore d e p o s i t , t h e r e a r e t h r e e main f a c t o r s which must be d e t e r m i n e d : 1) the source of the m e t a l s , 2) the m o b i l i z a t i o n and t r a n s p o r t a t i o n of m e t a l s , and 3) t h e i r c o n c e n t r a t i o n and d e p o s i t i o n . E v i d e n c e f o r a c o i n c i d e n t age of b a t h o l i t h and d e p o s i t s (Reynolds and S i n c l a i r , 1971; Andrew et al. , 1985) s u g g e s t s t h a t f a c t o r s 2 and 3 c o u l d be r e l a t e d d i r e c t l y t o b a t h o l i t h i c emplacement. The source of m e t a l s , on the o t h e r hand, i s l e s s c e r t a i n . Lead i s o t o p e s a r e a u s e f u l t o o l i n e s t a b l i s h i n g the provenance of ore d e p o s i t s (Doe and Zartman, 1979; Godwin et al. , 1982; B r e v a r t et al. , 1982; Cauet and W e i s s , 1983). P r e v i o u s l e a d i s o t o p e s t u d i e s of the Nel s o n b a t h o l i t h (Reynolds and S i n c l a i r , 1971), S l o c a n Group sediments (D. Ghosh, 1985, p e r s . comm.) and v e i n d e p o s i t s ( L e C o u t e u r , 1973; Andrew et al. , 1985) l e a d t o i n t e r p r e t a t i o n of the anomalous n a t u r e of S l o c a n l e a d s by v a r i o u s models which 123 124 i n v o l v e m i x i n g of components from two s e p a r a t e l e a d r e s e r v o i r s . In t h e s e models the b a t h o l i t h , which i s of uranium d e p l e t e d upper m a n t l e / l o w e r c r u s t a l d e r i v a t i o n , s u p p l i e d the n o n r a d i o g e n i c component, which, d u r i n g emplacement mixed w i t h upper c r u s t a l l e a d s t o produce the o b s e r v e d S l o c a n d a t a a r r a y (Reynolds and S i n c l a i r , 1971; Andrew et a l . , 1985). By a p p r o x i m a t i n g a lower c r u s t a l growth c u r v e , Andrew and o t h e r s (1985) show S l o c a n l e a d i s o t o p e d a t a t o l i e a l o n g a m i x i n g i s o c h r o n t h a t c o r r e s p o n d s t o the age of m i n e r a l i z a t i o n and presumably t o the time m i x i n g o c c u r r e d . Lead i s o t o p e abundances i n s e d i m e n t a r y l a y e r e d s u l p h i d e s i n t h i s s t u d y , i n d i c a t e a U/Pb environment c o n s i d e r a b l y lower than the s h a l e - c u r v e , p r o b a b l y r e f l e c t i n g the v o l c a n o g e n i c n a t u r e of upper s e c t i o n s of the S l o c a n Group. 4.2 TECTONOSTRATIGRAPHIC SETTING AND EVOLUTION The s t u d y a r e a l i e s w i t h i n t h e Omineca C r y s t a l l i n e B e l t i n s o u t h e a s t e r n B r i t i s h Columbia ( F i g . 4-1). T h i s t e c t o n o s t r a t i g r a p h i c b e l t i s the easternmost 'metamorphic w e l t ' of Monger and o t h e r s (1982), and i n c l u d e s t h e s u t u r e zone between Q u e s n e l l i a and the N o r t h American c o n t i n e n t . The e a s t e r n l i m i t of Q u e s n e l l i a p a r a l l e l s the a r c u a t e s t r u c t u r e of the Kootenay A r c , a complex metamorphic and s t r u c t u r a l b e l t bounded on the e a s t by the P u r c e l l A n t i c l i n o r i u m , and on the west by the Okanagan metamorphic 1 2 5 - 51 PACIFIC OCEAN /' <P MIDDLE EOCENE Coryel l Intrusives JURASSIC-EARLY EOCENE Qrmnitlca MIDDLE PALEOZOIC-EARLY JURASSIC Sadimanta and Volcanic* (Quaanallla) UPPER PALEOZOIC-PROTEROZIC Sadlmenta and Met asedimenta (Cratontc affinity) paraanaiases paragnaiases and orthognairaaa thruat faulta normal faulta F i g u r e 4-1. R e g i o n a l t e c t o n i c map of s o u t h e r n B r i t i s h Columbia, a f t e r P a r r i s h and o t h e r s (1985). I n s e t map shows l o c a t i o n w i t h r e s p e c t to major p h y s i o g r a p h i c s u b d i v i s i o n s of Canadian Cordl11 e r a . 126 and p l u t o n i c complex ( F i g . 4-1). The s t u d y a r e a encompasses the m a r g i n a l b a s i n which c o l l a p s e d d u r i n g a c c r e t i o n and was t h r u s t e a s t w a r d onto the c r a t o n i n the M i d d l e M e s o z o i c . L a t e P a l e o z o i c t o M i d d l e M e s o z o i c low grade metasedimentary rock of b o th c r a t o n i c and v o l c a n i c a r c provenance c h a r a c t e r i z e t h i s a l l o c h t h o n o u s package. Widespread a l k a l i c t o c a l c - a l k a l i n e i n t r u s i v e a c t i v i t y a f f e c t s the a r e a , the l a r g e s t nearby body b e i n g the M i d d l e J u r a s s i c N e l s o n b a t h o l i t h . 4.3 GEOLOGICAL SETTING The s t u d y a r e a i s u n d e r l a i n by L a t e T r i a s s i c S l o c a n Group sed i m e n t a r y r o c k s ( O r c h a r d , 1985). T h i s f i n e - g r a i n e d b l a c k c l a s t i c sequence has been i n t r u d e d by the M i d d l e J u r a s s i c N e l s o n b a t h o l i t h (160 ± 6 Ma, Duncan, 1982; H a r r i s o n , 1985) and s a t e l l i t e s t o c k s . The S l o c a n m i n i n g camp has produced 1.6 x 10 9 grams Ag, 0.22 x 10 6 tonnes Pb and 0.24 x 10 6 tonnes Zn from 172 p r o d u c e r s . The s i l v e r - r i c h f i s s u r e v e i n s a r e s i t u a t e d d o m i n a n t l y i n the c l a s t i c S l o c a n Group but some c r o s s c u t the N e l s o n b a t h o l i t h . S l o c a n d e p o s i t s occupy ' l o d e s ' which t r e n d e a s t e r l y t o n o r t h e a s t e r l y c r o s s c u t t i n g the r e g i o n a l f o l d s t r u c t u r e of t h e e n c l o s i n g L a t e T r i a s s i c r o c k s ( F i g . 4-2). The m i n e r a l i z e d zones are c h a r a c t e r i s t i c a l l y s m a l l t o medium tonnage Ag-Pb-Zn-Au v e i n s ( r a r e l y e x c e e d i n g 100,000 tonnes of o r e ) and l e s s commonly, where l o d e s c r o s s l i m e s t o n e , replacement -type d e p o s i t s . The m i n e r a l i z a t i o n i s g e n e r a l l y REGIONAL GEOLOGY AND SAMPLE LOCATION MAP (I) L O C A T I O N M A P STUDY AREA • AIHIMOTOH LEGEND E3 8 E3 E3 Feldspar porphyry Nelson granodiorta (porphytltlc) | | Slocan Group clastic sediments \ ..) Nemo Lake me I a sediments £53 Martin conglomerate rfTTl Kaslo Group volcanics SLOCAN LITHOLOOICAL SUCCESSION | o I Thin, inlarbedded sandy, limey and l ~ J tullaceous rocks Slete with limestone bods SYMBOLS A Geochemical sample location ® Pyrite Pb-isotope sample location GeoloQical contacts (delined, assumed) d 3 Lithological contects •mmmm Lode trend* . — Fault (defined, assumed) Gaotogy compltad (com: Ctirno 1034 Hadlav. 1045 and I9S2 Klepacki and Whaalai. )B LHIIa. 1000 Parriati, 1083 Raad. 1970 ?000 3000 SCALE 4000 5000m Figure 4-2. Regional geology of the central Slocan mining camp, showing rock geochemical, isotope and petrographic sample l o c a t i o n s . 1 28 b e l i e v e d t o be r e l a t e d t o i n t r u s i o n and t h e r e f o r e e q u i v a l e n t i n age t o the N e l s o n b a t h o l i t h (Reynolds and S i n c l a i r , 1971; Andrew et al. , 1985). 4.4 SAMPLE SELECTION S u l p h i d e samples were s e l e c t e d on a t e x t u r a l b a s i s t o e s t a b l i s h the i n i t i a l l e a d i s o t o p e c o m p o s i t i o n of s e d i m e n t a r y r o c k s of the S l o c a n Group, and.the s t a g e s of l e a d e v o l u t i o n c o r r e s p o n d i n g t o s p e c i f i c g e n e t i c p r o c e s s e s t h a t have a f f e c t e d the s e d i m e n t a r y u n i t ( i . e . d i a g e n e s i s and metamorphism). U n l i k e g a l e n a m i n e r a l i z a t i o n where the l e a d i s o t o p e c o m p o s i t i o n i s f r o z e n a t the time of f o r m a t i o n , the l e a d i n sediments c o n t i n u a l l y e v o l v e s from the time of d e p o s i t i o n t o the p r e s e n t , t h r o u g h decay of c o n t a i n e d uranium and t h o r i u m . The i n i t i a l i s o t o p i c c o m p o s i t i o n of the sediments can be d e t e r m i n e d by e i t h e r whole-rock a n a l y s i s of p r e s e n t day uranium, t h o r i u m and l e a d c o n t e n t s and w i t h the l e a d i s o t o p e c o m p o s i t i o n s b a c k - c a l c u l a t i n g t o the age of d e p o s i t i o n ; or d i r e c t l y by a n a l y s i s of l e a d i s o t o p e r a t i o s of s y n s e d i m e n t a r y m i n e r a l s c h a r a c t e r i z e d by a low or n e g l i g i b l e U/Pb r a t i o . P y r i t e has been u t i l i z e d t o d i r e c t l y e s t i m a t e i n i t i a l i s o t o p e s r a t i o s i n o t h e r s t u d i e s (Wampler and K u l p , 1964; Cauet and Weis, 1983) and i t s s y n s e d i m e n t a r y form i n the S l o c a n a r e a suggested u s i n g t h i s d i r e c t t e c h n i q u e . We assume t h a t p y r i t e f o r m a t i o n and/or l o c a l r e c r y s t a l l i z a t i o n i n c o r p o r a t e s l e a d t y p i c a l of the s u r r o u n d i n g sediments at 129 F i g u r e 4-3. A: S t r a t i f o r m l a y e r s and l e n s e s of f i n e g r a i n e d d i s s e m i n a t e d t o massive p y r i t e w i t h i n b l a c k carbonaceous s l a t e . Hand sample Pa-606, Payne Mt. B: P y r i t e f r a mboids p r e s e r v e d w i t h i n i m p e r v i o u s f i n e g r a i n e d carbonaceous l a y e r s . R e f l e c t e d l i g h t photo-m i c r o g r a p h of sample PA-606. C: SEM b a c k s c a t t e r p h o t o m i c r o g r a p h of sample PA-6A-8, Payne Mt., showing v a r i a t i o n s i n s u l p h i d e c h a r a c t e r . D i s s e m i n a t e d f r a m b o i d s i n rock m a t r i x t o p o r o u s / n e t t e x t u r e d and massive where r e c r y s t a l l i z e d . L o c a l l i z e d i n c r o s s c u t t i n g t e n s i o n gash ( l o w e r l e f t t o upper r i g h t ) i s more massive p y r i t e which c o n t a i n s i n c l u s i o n s of c h a l c o p y r i t e and s p h a l e r i t e . 131 the time of i n c o r p o r a t i o n , and t h a t a d d i t i o n or l o s s of l e a d , uranium or t h o r i u m has o c c u r e d i n the whole rock samples. To a pproximate c l o s e d system b e h a v i o u r s u l p h i d e s o c c u p y i n g c r o s s c u t t i n g s t r u c t u r e s were a v o i d e d d u r i n g s a m p l i n g . E a r l i e r l e a d i s o t o p e s t u d i e s (Reynolds and S i n c l a i r , 1971; L e Couteur, 1973; Cox, 1979; Andrew et al. , 1985) f o c u s s e d on the v e i n d e p o s i t s ( i . e . ' h y d r o t h e r m a l ' s t a g e ) . The emphasis of t h i s s tudy i s the e a r l i e r s t a g e s — t h o s e of d i a g e n e s i s and metamorphism. The l e a d i s o t o p e d a t a a r e t a b u l a t e d i n T a b l e 4-1, t o g e t h e r w i t h the predominant t e x t u r e and p a r a g e n e t i c i n t e r p r e t a t i o n f o r each sample. The f i r s t number r e f e r s t o the map l o c a t i o n ( F i g . 4-2), the second i d e n t i f i e s the sample on the ( 2 0 6 P b / 2 0 " P b v s . 2 0 7 P b / 2 0 " P b ) and ( 2 0 6 P b / 2 0 a P b v s . 2 0 8 P b / 2 0 " P b ) diagrams. I n d i v i d u a l d e s c r i p t i o n s and p h o t o m i c r o g r a p h s f o r each sample f o l l o w , i n o r d e r of a p a r a g e n e s i s i n f e r r e d from s u l p h i d e t e x t u r e s . P y r i t e f r a m b o i d s comprise sample PA-606D. These formed e i t h e r synchronous w i t h s e d i m e n t a t i o n or d u r i n g e a r l i e s t d i a g e n e s i s , and have been p r e s e r v e d from l a t e r a l t e r a t i o n " or a d d i t i o n of m a t e r i a l due t o the impermeable n a t u r e of t h e i r s l a t e host ( F i g . 4-3b). A l t h o u g h r e c r y s t a l l i z a t i o n has p a r t l y o b l i t e r a t e d the d e l i c a t e i n t e r n a l t e x t u r e d e f i n e d by i n d i v i d u a l m i c r o c r y s t a l l i t e s , s p h e r i c a l o u t l i n e s suggest no s u b s t a n t i a l m i g r a t i o n of the s u l p h i d e s has o c c u r e d ( F i g . 4-3b). Permeable i n t e r b e d d e d c r y s t a l t u f f s and sandy l a y e r s o c c u r w i t h i n t h i s same carbonaceous s h a l y h o r i z o n . F l u i d F i g u r e 4-4. A: S t r a t i f o r m p y r i t e l a y e r s , hand sample CD-1, Cody Ck. Lens of more c o a r s e g r a i n e d p y r i t e (bottom r i g h t ) , c o n s t i t u t e s sample CD-.1C, f i n e r g r a i n e d p y r i t e from same l a y e r , CD-1F. B: C o n t a c t zone between r e c r y s t a l l i z e d p y r i t e (white, on l e f t ) and m o s t l y u n a f f e c t e d sediments ( r e l i c t f r a mboids) on r i g h t . A c t u a l c o n t a c t 1s obscured by q u a r t z p r e s s u r e shadow, (medium g r e y ) . R e f 1 e c t e d l i g h t photomicrograph of sample PA-2. C: O x i d i z e d carbonaceous s l a t e , hand sample PR-4, from Payne Rd. P y r i t e o c c u r s as f i n e - g r a i n e d s t r a t a b o u n d d i s s e m i n a t e d c r y s t a l s ( S o i s h o r i z o n t a l ) , r e c r y s t a l l i z e d i n e x t e n s i o n gashes ( t r e n d from r i g h t to l e f t at 45' t o S D ) and i n c l e a v a g e p a r a l l e l v e i n l e t s ( S i t r e n d s from r i g h t to l e f t a t 10' to S o ) . 0: P y r i t e g r a i n s i z e v a r i a t i o n w i t h i n s u l p h i d e - r i c h s t r a t i f o r m l a y e r . Coarse p y r i t e w i t h i n e x t e n s i o n f r a c t u r e comprises sample PR-4. R e f l e c t e d l i g h t photomicrograph. 133 134 f l o w a l o n g t h e s e permeable l a y e r s c o n t r o l l e d r e c r y s t a l l i z a t i o n and produced p a r a l l e l l a y e r s and l e n s e s up t o 0.6 cm wide of porous or open-mesh t e x t u r e d s t r a t i f o r m p y r i t e ( F i g . 4-3a and 4-3c). These p y r i t e l e n s e s were o r i g i n a l l y i n t e r p r e t e d as d i a g e n e t i c . P b - i s o t o p e r a t i o s suggest a l a t e r s t a g e f o r t h e i r r e c r y s t a l l i z a t i o n . Sample PA-606B i s a composite of s e v e r a l l a y e r s of t h i s p y r i t e . F i g u r e 4-4a i n d i c a t e s g r a i n s i z e v a r i a t i o n , d i s t r i b u t i o n and o v e r a l l t e x t u r a l r e l a t i o n s h i p s of samples CD-1C and CD-1F. Both samples o r i g i n a t e from a s i n g l e s t r a t i f o r m s u l p h i d e c o n c e n t r a t i o n i n a carbonaceous s l a t e . CD-1C r e p r e s e n t s the ' c o a r s e - g r a i n e d c o r e ' (>100 m i c r o n s ) and CD-1F the o u t e r ' f i n e - g r a i n e d e nvelope' (<100 m i c r o n s ) . G r a i n s i z e v a r i a t i o n d e f i n e s degree of r e c r y s t a l l i z a t i o n and not two s e p a r a b l e e v e n t s . Sample PR-4 c o n s i s t s of o n l y the >150 m i c r o n p y r i t e s i t u a t e d i n t e n s i o n gashes. These e x t e n s i o n s t r u c t u r e s have deve l o p e d w i t h i n and appear c o n f i n e d t o the s u l p h i d e - r i c h l a y e r ( F i g . 4-4c). The s u l p h i d e l a y e r s (2.0 mm t h i c k ) p a r a l l e l l a y e r i n g and are composed of a n h e d r a l <100 m i c ron p y r i t e g r a i n s . The s i z e d i f f e r e n c e p e r m i t t e d s e p a r a t i o n of the p y r i t e t h a t o c c u p i e s the e x t e n s i o n gashes ( F i g . 4~4d). The continuum t h a t e x i s t s between s y n s e d i m e n t a r y , d i a g e n t i c and metamorphic p r o c e s s e s i s i l l u s t r a t e d i n the s u l p h i d e forms which c o n s t i t u t e sample WW-22A ( F i g . 4-5). The s u l p h i d e s , t o t a l l i n g about 2.0 volume p e r c e n t , a r e most c o n s p i c o u s as e u h e d r a l p y r i t e cubes f l a t t e n e d p e r p e n d i c u l a r 135 F i g u r e 4-5. Carbonaceous s l a t e , sample WW-22A, Whitewater Ck. A: T r a n s m i t t e d l i g h t p h o t o m i c r o g r a p h showing t r a n s p o s e d l a y e r i n g and q u a r t z f i l l e d h y d r a u l i c f r a c t u r e s ( t r e n d h o r i z o n t a l ) . P y r i t e cubes ( b l a c k ) rimmed by q u a r t z p r e s s u r e shadows. B: S y n k i n e m a t i c p y r i t e growth e n c l o s e d e a r l i e r f r a m b o i d a l p y r i t e . I n c l u s i o n s of NiS ( b r i g h t w h i t e ) and TiO (dark grey) a r e p r e s e n t i n the l a t e r p y r i t e . Note s o l i t a r y f r a m b o i d a t r i g h t , l a c k s p y r i t e o v e r g r o w t h . SEM b a c k s c a t t e r p h o t o m i c r o g r a p h of sample WW-22A. C: SEM pho t o m i c r o g r a p h d e t a i l of c e n t r a l a r e a i n F i g u r e 4-5B. P y r i t e c o r e shown t o be composed of fram b o i d s ( u n i m o d a l - s i z e d rhombic c r y s t a l s of p y r i t e ) and s h a l e . 137 t o f o l i a t i o n ( F i g . 4~5a). Synsedimentary f r a m b o i d s a r e p r e s e r v e d i n t a c t as c o r e s i n l a t e p y r i t e ( F i g . 4-5b and 4-5c) a n d ' w i t h i n f i n e g r a i n e d c a r b o n - r i c h i m p e r v i o u s l a y e r s . The host rock i s a carbonaceous ( 2 . 1 % t o t a l carbon) s l a t e . Q u artz f i b e r - f i l l e d h y d r a u l i c f r a c t u r e s i n d i c a t e h i g h pore p r e s s u r e d e f o r m a t i o n . D e f o r m a t i o n has t r a n s p o s e d bedding and h y d r a u l i c f r a c t u r e s . S y n k i n e m a t i c - p y r i t e growth, r e c r y s t a l l i z a t i o n and d e p o s i t i o n of q u a r t z f i b e r - f i l l e d p r e s s u r e shadows i n zones of l e a s t p r i n c i p a l s t r e s s i n d i c a t e c o n t i n u e d f l u i d m i g r a t i o n ( F i g . 4~5a). 4.5 A N A L Y T I C A L P R O C E D U R E A l l s h a l e samples were c r u s h e d and s i e v e d t o s p e c i f i e d s i z e f r a c t i o n s d e t e r m i n e d m i c r o s c o p i c a l l y t o y i e l d l i b e r a t i o n of p y r i t e . S i z e f r a c t i o n s f o r the s i x samples i n c l u d e d : minus 100 p l u s 200 mesh (4 s a m p l e s ) , minus 70 p l u s 100 mesh (1 sample), and minus 200 p l u s 400 mesh (1 sample). Heavy l i q u i d s e p a r a t i o n t e c h n i q u e s u s i n g t e t r a b r o m e t h a n e and methylene i o d i n e produced p y r i t e s e p a r a t e s of g r e a t e r than 90% p u r i t y . Magnetic s e p a r a t i o n was f o l l o w e d by h a n d - p i c k i n g under a b i n o c u l a r m i c r o s c o p e of a l l but sample PA-606. T h i s i n c r e a s e d the sample p u r i t y t o about 95% f o r t h e f i v e samples t r e a t e d . P u r i t y of the s i x t h sample (PA-606) c o u l d not be improved beyond about about 90%, due t o t h e f i n e - g r a i n s i z e of f r a m b o i d s (10-20 u i n d i a m e t e r ) . A f t e r m i n e r a l s e p a r a t i o n , p y r i t e c o n c e n t r a t e s were s u b m i t t e d t o the Geochronology L a b o r a t o r y , Department of Geology and 138 P h y s i c s , U n i v e r s i t y of A l b e r t a , Edmonton, A l b e r t a f o r i s o t o p i c a n a l y s i s . P y r i t e samples were d i v i d e d i n t o two, one p a r t <0.2 gm and the remainder >0.2 gm. The s m a l l e r p a r t of the sample was decomposed i n c o n c e n t r a t e d HN0 3; l e a d from t h i s s o l u t i o n i s r e f e r r e d t o as the t o t a l f r a c t i o n or 'T'. The l a r g e r p a r t of the sample was l e a c h e d i n warm HC1 o v e r n i g h t ; the r e s u l t i n g s o l u t i o n l e a d was c a l l e d 'L'. The r e m a i n i n g m a t e r i a l was soaked i n d i s t i l l e d water and then d i s s o l v e d i n c o n c e n t r a t e d HN0 3; s o l u t i o n from t h i s r e s i d u e y i e l d l e a d c a l l e d 'R'. Lead was p u r i f i e d f i r s t i n an a n i o n exchange column u s i n g an HBr element, then i n an a n i o n exchange column u s i n g an HC1 element. I s o t o p e r a t i o s were measured on a MM30 mass s p e c t r o m e t e r u s i n g a s t a n d a r d s i l i c a g e l - p h o s p h o r i c a c i d on a s i n g l e f i l a m e n t method. Data were n o r m a l i z e d t o a b s o l u t e r a t i o s u s i n g f a c t o r s o b t a i n e d from NBS 981 and 982 l e a d s t a n d a r d s . R e p l i c a t e a n a l y s i s of st a n d a r d s i n d i c a t e s a r e p r o d u c i b i l i t y of 0.023% ( 2 0 6 P b / 2 0 4 P b ) , 0.028% ( 2 O 7 P b / 2 0 , P b ) and 0.033% ( 2 0 8 P b / 2 0 4 P b ) at one s t a n d a r d d e v i a t i o n . E r r o r s a r e r e p o r t e d as e i t h e r the measuring e r r o r f o r the run or t h a t of r e p r o d u c i b i l i t y , whichever was l a r g e r (Information above is from G. Cummi ngs, 1986, written communication) Thorium, uranium and p o t a s s i u m have a l s o been d e t e r m i n e d by gamma-ray s p e c t r o s c o p y on s i x samples from S l o c a n s e d i m e n t s . C o n c e n t r a t i o n s and r a t i o s (Th, U, K, and Pb) t o g e t h e r w i t h M~value c a l c u l a t i o n s a r e p r e s e n t e d i n 139 T a b l e 4-2A. The sample l o c a t i o n s a r e shown on F i g u r e 4-2. A n a l y s e s were done by T. Lewis a t the P a c i f i c G e o s c i e n c e C e n t r e . The t e c h n i q u e d e t e r m i n e s gamma ray s p e c t r a from powdered rock u s i n g two s o l i d s t a t e G e ( L i ) d e t e c t o r s . The o r i g i n a l method ( L e w i s , 1974) has been m o d i f i e d such t h a t a c o n s t a n t sample s i z e of 330 g i s now used (Lewis et al. , 1984). Sample p r e p a r a t i o n i n v o l v e d c r u s h i n g and g r i n d i n g samples t o -100 mesh. The d a t a are p r e s e n t e d i n Table 4-2a. 4.6 LEAD ISOTOPE DATA The p y r i t e l e a d d a t a (Table 4-1) a r e shown on c o n v e n t i o n a l 2 0 7 P b / 2 0 a P b vs 2 0 6 P b / 2 0 ' , P b ( F i g . 4-6) and 2 0 8 P b / 2 o a p b v s 2 0 6 P b / 2 o « p b ( F i g > 4 _ 7 ) a i a g r a m s . p l o t t e d a l s o " a r e the s h a l e c u r v e of Godwin and S i n c l a i r (1982), the B l u e b e l l c u r v e of Andrew et al. (1985) and the l e a d i s o t o p e f i e l d f o r p e l a g i c sediments (Doe and Zartman, 1979) a d j u s t e d t o a L a t e T r i a s s i c p o s i t i o n (M and W of 12.3 and 49.0 r e s p e c t i v e l y were u s e d ) . The l e a c h , r e s i d u e and t o t a l r e s u l t s f o r a l l samples d e f i n e a l i n e a r t r e n d which p l o t s a p p r o x i m a t e l y midway between the s h a l e and B l u e b e l l c u r v e s ( F i g . 4-6). The l e a s t r a d i o g e n i c sample c o r r e s p o n d s t o the p a r a g e n e t i c a l l y o l d e s t ( i . e . f r a m b o i d s ) and l i e s a t the l e f t - e n d of t h i s t r e n d w i t h i n the L a t e T r i a s s i c p o s i t i o n of the p e l a g i c sediment f i e l d . In c o n t r a s t , the more r a d i o g e n i c samples which c o r r e s p o n d t o l a t e r - s t a g e p y r i t e m i n e r a l i z a t i o n l i e Table 4-1 Sample description and lead Isotope ratios from pyrite concentrates. Figure 4-2 gives sample locations. SAMPLE NO. SULPHIDE FORM PARAGENETIC LEAD ISOTOPE RATIOS MAP / PLOTS STAGE 2 ° 6 p b / 2 0 4 p b 207p b/204 p b 208p b/204p b [ 1 slgma error % ] CD-1 K a ) open-mesh, anhedral diagenetlc L 18 878 [ .02] 15 642 03] 38 652 • 03] (b) crystal aggregates T 18 874 .02] 15 644 .03] 38 668 • 03] (c) R 18 869 [ .02] 15 631 .03] 38 637 .03] CD-1 2(a) anhedral blebs re- diagenetic L 18 971 [ .02] 15 656 .03] 38 751 03] (b) crystal Hzed framboids T 18 896 02] 15 646 .03] 38 640 .03] (c) R 18 873 [ 02] 15 641 t .03] 38 618 .03] WW-22A 3(a) euhedral & subhedral syngenetIc L 19 761 [ 02] 15 676 .03] 38 841 [ 0 3 ] (b) crystal aggregates with synk i nemat ic T 20 484 .03] 15 727 .03] 38 709 03] (c) framboid cores R 19 750 .02] 15 689 .03] 38 674 .03] PR-4 4(a) subhedral, massive synk1nemat ic L 19 993 .02] 15 693 .03] 38 740 .03] (b) grains occupying tension T 19 682 .08] 15 683 .08] 38 614 .08] (c) gashes within sulphide R 19 214 .02] 15 649 .03] 38 567 .03] band PA-60G 5(a) r e c r y s t a l l i z e d lenses diagenet1c L 19 120 .02] 15 659 .03] 38 741 .03] (b) open-mesh, massive & T 18 979 .02] 15 642 .03] 38 686 .03] (c) r e l i c t framboids R 18 946 .02] 15 637 .03] 38 653 .03] PA-606 6(a) framboids syngenet1c L 17 815 .02] 15 581 .03] 38 532 .03] * (b) T 18 501 .03] 15 617 .03] 38 506 .03] (c) R 18 654 .02] 15 629 .03] 38 417 .03] L = OVERNIGHT LEACH OF >0.2gm SAMPLE SPLIT R = RESIDUE OF LEACH SAMPLE T = TOTAL DISSOLUTION OF 0.2gm SAMPLE SPLIT * = DUBIOUS RESULT 141 d i s p l a c e d t o the r i g h t . T h i s d i r e c t c o r r e l a t i o n between abundance of r a d i o g e n i c l e a d and p a r a g e n e t i c p o s i t i o n i s c o n s i s t e n t w i t h the assumptions made e a r l i e r w i t h r e s p e c t t o r e c r y s t a l l i z a t i o n and i n c o r p o r a t i o n of l o c a l r a d i o g e n i c l e a d . The r e g r e s s i o n l i n e s shown i n F i g u r e s 4-6 and 4-8 a r e f o r r e s i d u e v a l u e s , ( t h e l e a c h samples were r e g r e s s e d s e p a r a t e l y ) , those shown i n F i g u r e s 4-7 and 4-9 ar e .for a l l samples e x c e p t 6A. 4.7 DATA INTERPRETATION Synsedimentary samples 6b and 6c p l o t w i t h i n the p e l a g i c l e a d f i e l d i n both l e a d - l e a d diagrams ( F i g . 4-6 and 4-7). Lead of t h i s c o m p o s i t i o n i s the same as the l e a d i n an average orogene and the most o b v i o u s m a n i f e s t a t i o n of the o r o g e n i c environment a r e a c t i v e v o l c a n i c i s l a n d a r c s (Doe and Zartman, 1979). The o r o g e n i c l e a d r e s u l t s from m i x i n g of o c e a n i c ( b a s a l t s and p e l a g i c s e d i m e n t s ) , c o n t i n e n t a l ( e l a s t i c s and c h e m i c a l s e d i m e n t s ) , lower c r u s t a l and mantle m a t e r i a l s d u r i n g s u b d u c t i o n and magma g e n e s i s . The sed i m e n t a r y l e a d , as i n d i c a t e d by s y n s e d i m e n t a r y s u l p h i d e , i s p r o b a b l y d e r i v e d from e i t h e r o r d i n a r y p e l a g i c or o r o g e n i c l e a d . Lower c r u s t / u p p e r mantle l e a d e v o l u t i o n i s d e s c r i b e d by the B l u e b e l l c u r v e (Andrew et al. , 1985). C o n t i n e n t a l , or more s p e c i f i c a l l y , N o r t h American provenance s e d i m e n t a r y l e a d e v o l u t i o n i s r e p r e s e n t e d by the s h a l e c u r v e (Godwin and S i n c l a i r , 1982). The m i d d l e p o s i t i o n of s u l p h i d e d a t a F i g u r e 4 - 6 . S u l p h i d e - l e a d p l o t o f " " P b / ! 0 4 P b v s J 0 « P b / ! ° * P b d a t a f r o m T a b l e 4 - 1 . D a t a p l o t t e d w i t h 1 - s igma e r r o r , a : c o r r e s p o n d s t o l e a c h , b : the t o t a l and c : r e s i d u e s a m p l e s . The p e l a g i c s e d i m e n t f i e l d (Doe and Z a r t m a n , 1979) i s shown a t L a t e T r i a s s i c p o s i t i o n . G r o w t h c u r v e s shown a r e t h o s e o f Godwin and S i n c l a i r (1982) and Andrew et a). ( 1 9 8 5 ) . 15.7 H 15.6 H . Q CL o CM 15.4 Shale Curve 0.50 0.0 Ma 4b 0 o3. 3 c Pelagic Sediments 0.0 Ma Bluebell Curve / 2 0 4 Pb Error s l o p e $ T y p i c a l a n a l y t i c a l error (1 s igma) 17.5 18.0 18.5 19.0 2 0 6 P b / 2 0 4 P b 19.5 20 .0 2 0 . 5 co F i g u r e 4 - 7 . S u l p h i d e - 1 e a d p l o t o f « ° , P b / * 0 4 P b vs * ° « P b / ' ° 4 P b o f d a t a i n T a b l e 4 - 1 . C i r c l e s d e n o t e l e a c h s a m p l e ; t r i a n g l e s a r e f o r t o t a l and s o l i d c i r c l e s t h e r e s i d u e f o r e a c h o f t h e s i x s u l p h i d e s a m p l e s . The r e g r e s s i o n l i n e i s f o r a l l v a l u e s e x c e p t 6 a . The L a t e T r i a s s i c p o s i t i o n f o r p r e s e n t day p e l a g i c s e d i m e n t f i e l d (Doe and Z a r t m a n , 1979) i s shown t o g e t h e r w i t h the s h a l e c u r v e of Godwin and S i n c l a i r ( 1 9 8 2 ) , and B l u e b e l l c u r v e o f Andrew et a}. ( 1 9 8 5 ) . 146 i n d i c a t e s an e v o l u t i o n i n t e r m e d i a t e t o t h e s e two 'end-member' systems. A d i s t r i b u t i o n p a t t e r n from l e a s t t o most r a d i o g e n i c i s e v i d e n t f o r the r e s i d u e , t o t a l and l e a c h p o r t i o n s r e s p e c t i v e l y of most samples. L e a c h i n g samples removes about 0.5 m i c r o n from the s u r f a c e of the p y r i t e (1.0 m i cron i n 2 days l e a c h , Wampler and K u l p , 1964) and w i t h t h i s h o p e f u l l y any s u r f i c i a l l e a d produced by r a d i o g e n i c decay of uranium or t h o r i u m from the s u r r o u n d i n g s e d i m e n t s . In most c a s e s the l e a c h a t e i s e n r i c h e d s l i g h t l y i n r a d i o g e n i c i s o t o p e s . E x c e p t i o n s t o t h i s p a t t e r n a r e samples 6a and 3b. For samples 3 and 6 t h e r e a r e mass b a l a n c e i n c o n s i s t e n c i e s (the l e a c h p l u s the r e s i d u e do not e q u a l the t o t a l ) . These might r e p r e s e n t poor a n a l y s e s or i n d i c a t e the d i f f i c u l t i e s i n h e r e n t i n making r e p r e s e n t a t i v e s p l i t s of s m a l l samples. P r e p a r i n g a h i g h p u r i t y f r a m b o i d c o n c e n t r a t e f o r sample 6 r e s u l t e d i n a mere 0.20 grams of sample. The l e a d r a t i o d e t e r m i n e d f o r l e a c h sample 6a c o u l d o n l y r e s u l t from c o n t a m i n a t i o n , as t h e r e i s no r e a s o n a b l e g e o l o g i c a l i n t e r p r e t a t i o n f o r such a low v a l u e . T h i s v a l u e was o m i t t e d from f u r t h e r c a l c u l a t i o n s . The n a t u r e of sample 3 ( F i g . 4-5) i n d i c a t e s wide v a r i a t i o n i n the p r o c e s s e s of s u l p h i d e m i n e r a l i z a t i o n . The more r a d i o g e n i c r e s i d u e (3b) might suggest uranium r i c h m a t e r i a l i n the c o r e s of p y r i t e . A l t e r n a t i v e l y the l e s s r a d i o g e n i c l e a d may have o r i g i n a t e d o u t s i d e the sediments and been i n t r o d u c e d l a t e r . 147 T h e o r e t i c a l l y the r e s i d u e and l e a c h samples s h o u l d each d e f i n e s e p a r a t e l i n e a r a r r a y s which i n t e r s e c t a t a common p o i n t c o r r e s p o n d i n g t o the i n i t i a l i s o t o p e c o m p o s i t i o n . In t h i s case the p o i n t would be the average f r a m b o i d a l sample (6) . Le a s t squares l i n e a r r e g r e s s i o n (York, 1969) of the 6 r e s i d u e v a l u e s g i v e s a s l o p e of 0.056 ± 0.005 (1 sigma) and an i n t e r c e p t of 14.58 ± 0.13 ( F i g . 4-6). A c c o r d i n g t o the r e l a t i o n s h i p : ( 2 0 7Pb/ 2 0«Pb)t 2 - ( ' O ' P b / ^ P b H , 1 ( e X 2 t l - e X 2 t 2 ) (2°«PB/ 2 0'Pb)t 2 - ( 2 0 6 P b / 2 0 l , P b ) t 1 137.88 ( e X , t l - e X l t 2 ) -10 where the decay c o n s t a n t s a r e X, ( 2 3 8 U ) = 1.55125 x 10 -1 -10 -1 year and X 2 ( 2 3 5 U ) = 9.8485 x 10 year ( J a f f e y et al. , 1971). A f a m i l y of ( t , ) s o l u t i o n s e x i s t which c o r r e s p o n d t o d i f f e r e n t assumed ( t 2 ) and s a t i s f y e g u a t i o n 1. G e o l o g i c a l c o n s t r a i n t s such a s ; age of sediments ( s t r a t i f o r m d e p o s i t s ) or age of m i n e r a l i z a t i o n ( e p i g e n e t i c d e p o s i t s ) p r o v i d e r e a s o n a b l e c o n t r o l f o r t 2 m i n i m i z i n g or a t l e a s t b r a c k e t i n g the range of l i k e l y s o l u t i o n s . The age of m i n e r a l i z a t i o n i s g e n e r a l l y a c c e p t e d (Andrew et al . , 1985; Brame, 1979; C a i r n e s , 1935) t o be the same as the age of the Ne l s o n b a t h o l i t h 160 ± 6 Ma (Duncan and P a r r i s h , 1979; H a r r i s o n , 1985). A so u r c e age ( t , ) of 295 Ma can be c a l c u l a t e d by assuming a m i n e r a l i z a t i o n age ( t 2 ) of 165 Ma, or 315 Ma 1 48 assuming ( t 2 ) of 155 Ma. The e a r l i e r date a g r e e s w e l l w i t h t h o s e e s t a b l i s h e d i n d e p e n d e n t l y by e a r l i e r w o r k e r s . The age of the sediments has been e s t a b l i s h e d as L a t e T r i a s s i c (225 Ma: Armstrong, 1983) by conodonts (O r c h a r d , 1985). In view of the e r r o r i n s l o p e f o r the l i n e of be s t f i t , t h e r e i s r e a s o n a b l e agreement f o r t , between 225 and 295 Ma. T h i s assumes t h a t the mean f r a m b o i d v a l u e ( F r ) i s r e p r e s e n t a t i v e of t h e . i n i t i a l r a t i o a t the time of d e p o s i t i o n . L i n e a r r e g r e s s i o n of the l e a c h v a l u e s (n = 5) g i v e s a s l o p e of 0.041 ± 0.005 and an i n t e r c e p t of 14.86 ± 0.10. The l i n e i n t e r s e c t s the average f r a m b o i d sample w i t h i n a n a l y t i c e r r o r . The v a l u e f o r s l o p e i s l e s s than the p r e s e n t day ( t 2 = 0) i n s t a n t a n e o u s growth v a l u e and i s an i n d i c a t i o n of the r e l a t i v e l y l a r g e e r r o r r e l a t e d t o the s h o r t l e n g t h of the anomalous l e a d l i n e and the s m a l l number of samples. L i n e a r r e g r e s s i o n of a l l samples except 6A (n = 17) g i v e s a s l o p e of 0.113 ± 0.006 and an i n t e r c e p t of 36.48 ± 0.11 ( F i g . 4-7). An average e v o l u t i o n t r e n d of 2 0 B P b and 2 0 6 P b might be i n t p r e t e d f o r the i n t e r v a l d e f i n e d between i n i t i a l r a t i o (sample 6) and the c l u s t e r of d a t a which r e p r e s e n t metamorphic r e c r y s t a l l i z a t i o n . The p a r a g e n e t i c a l l y l a t e r samples (3 and 4) a r e p r e f e r e n t i a l l y e n r i c h e d i n u r a n o g e n i c ( 2 0 6 P b ) w i t h l i t t l e a d d i t i o n a l t h o r o g e n i c ( 2 0 8 P b ) . These low Th/U r a t i o samples l i e markedly t o the r i g h t of the s h a l e c u r v e and account f o r the low s l o p e of the r e g r e s s i o n l i n e . 1 49 4.8 DISCUSSION The anomalous n a t u r e of S l o c a n v e i n l e a d s have been i n t e r p r e t e d by v a r i o u s models which i n v o l v e m i x i n g of two s e p a r a t e l e a d r e s e r v o i r s (Reynolds and S i n c l a i r , 1971; L e C o u t e u r , 1973; Andrew et al. , 1985). An a l t e r n a t i v e model (LeCo u t e u r , 1973) i n v o k e s c o n t a m i n a t i o n of ore b e a r i n g s o l u t i o n s t h r o u g h p r e f e r r e n t i a l e x t r a c t i o n of r a d i o g e n i c l e a d from w a l l r o c k a d j a c e n t t o s o l u t i o n channelways. The l a t t e r e x p l a n a t i o n a d d r e s s e s the c o n c e n t r i c z o n a t i o n p a t t e r n of v e i n d e p o s i t 2 0 6 P b / 2 0 4 P b c o n t o u r s which i s c e n t e r e d on the n o r t h e a s t edge of the b a t h o l i t h (LeCouteur, 1973). Trace elements i n s u l p h i d e s ( S i n c l a i r , 1967) and m e t a l abundances ( S i n c l a i r , 1979) r e f l e c t s i m i l i a r z o n a l p a t t e r n s which s p a t i a l l y o v e r l a p the i s o t o p e z o n a t i o n . The l e a s t r a d i o g e n i c c e n t r a l zone o c c u r s i n the v i c i n i t y of Sandon and c o r r e s p o n d s t o upper s e c t i o n s of the S l o c a n Group. The S l o c a n Group s e d i m e n t a r y sequence i s d e r i v e d from two d i s t i n c t p rovenances. The h i g h e s t p a r t s of the sequence ar e r e l a t i v e l y r i c h i n m a t e r i a l d e r i v e d from a b a s i c s o u r c e , whereas lower down, the Group has a more s i l i c e o u s c h a r a c t e r (Cox, 1979). T h i s t w o - f o l d d i s t i n c t i o n i s a l s o e v i d e n t i n the l e a d i s o t o p i c d a t a r e p o r t e d here ( F i g . 4-8 and 4-9). Low 2 0 7 P b / 2 0 < t P b v a l u e s a r e t y p i c a l f o r p y r i t e samples from the upper t u f f a c e o u s h o r i z o n s . The mean whole-rock d a t a ( T a b l e 4-2b) a r e shown p l o t t e d on F i g u r e 4-8 and 4-9 (D. Ghosh, 1985, p e r s . comm.). These d a t a have been c o r r e c t e d f o r uranium and t h o r i u m decay f o r 1 5 0 Table 4-2A Thorium, uranium.and lead concentrations of Slocan sediments. SAMPLE LITHOLOGY ELEMENT U Th ( P P m ) 2313 u W U/^Pb S 3 STh/ 2 0»Pb K % Th/U San 01 slate 4 .91 4.56 20.00 15.63 14 . 52 2. 46 0.9 BL 303 slate 3 ,45 7.30 -- — — 3. 00 2.1 WW 2B slate 3 .86 8.40 12.00 20.49 44.58 3. 02 2.2 1708 greywacke 1 .54 2.83 45.00 2. 18 4.00 1 . 28 1.8 BO 1005 quartz 1te 4 .35 4.62 22.00 12.59 13.37 2. 13 1 . 1 PA 606 slate 5 .41 10.40 23.00 14.98 28.80 2. 83 1.9 Table 4-2B Thorium, uranium and lead concentrations of Slocan sediments, and whole rock lead whole rock lead Isotope ratios with corrections for 165 and 247 Ma (Ghosh, 1985, pers. comm.) PRESENT-DAV RATIOS SAMPLE LITHOLOGY ELEMENT (ppm) u W U Th Pb M 8 U / S 0 4 p b 2 3 i T n / 2 0 4 P D LEAD ISOTOPE RATIOS 206/204 207/204 208/204 [ 1 Sigma error % ] A sla t e 2. 29 2.00 10.00 14.54 13.. 13 19 .080 ( .001 ] 15 .661 t .001] 38 .917 t .002] C slate 3. 00 6.00 12.00 15.91 32.89 19 , 161 t .002] 15 .674 [ .002) 38 .988 [ .005] D slate 3. .00 13.00 19.OO 10.05 45.00 18 .995 ( .010] 15 .665 [ .008] 39 . 156 t .020] F slate 3. , 17 19.00 20.00 10.09 62.51 18 .998 t .002] 15 .678 I .001 ] 39 . 173 t .006] G 1imestone 3 ,00 20.00 20.00 9.51 65.53 19 .034 [ .012] 15 .690 [ .009] 38 817 t .020] Arithmetic mean(X) « 19. .053 t .007] 15. .673 [ .004] 39 ,010 [ .01 1 ] Standard I deviation (S) = 0 .069 0 .012 0 . 154 Standard error of mean (S'rf'4) " 0 .031 0. .005 0 ,069 RATIOS CALCULATED FOR 165 Ma 18.703 18.748 18.734 18.736 18.787 15.642 15.654 15.652 15.665 15.678 38.809 38.718 38.787 38.661 38.280 Arithmetic mean (X) • 18.741 Standard deviation (S) • 0.030 Standard error of mean (S-ri'£) " 0.013 15.658 0.013 0.006 38.651 0.215 0.096 RATIOS CALCULATED FOR 247 Ma 18.512 18.540 18.603 18.604 18.663 15.632 15.642 15.645 15.658 15.671 38.756 38.584 38.603 38.404 38.404 Arithmetic mean (X) • 18.584 Standard deviation (S) - 0.059 Standard error of mean (S-n'4) " 0.026 15.649 0.015 0.007 38.471 0.286 0. 128 F i g u r e 4 - 8 . Su1 p h i d e - 1 e a d p l o t s of ? ° ' P b / ! 0 4 P b vs ' ° 6 P b / ! 0 4 P b d a t a f r o m T a b l e s 4 - 2 b , 4 -3 and 4 - 4 . S o l i d s q u a r e s d e n o t e f e l d s p a r l e a d s f rom N e l s o n b a t h o l i t h R e y n o l d s and S i n c l a i r ( 1 9 7 1 ) . C r o s s e s mark one s t a n d a r d d e v i a t i o n f rom t h e mean o f v e i n d e p o s i t s ( V n ) , w h o l e - r o c k (WRx), w h o l e - r o c k c o r r e c t e d t o 247 Ma ( W R x ' ) , f r a m b o i d a l ( F r ) and metamorphic (Mm) p y r i t e . Dashed f i e l d e n c l o s e s d i s t r i b u t i o n o f v e i n d e p o s i t s . R e g r e s s i o n l i n e i s f o r r e s i d u e v a l u e s . S h a l e c u r v e o f Godwin and S i n c l a i r (1982) and B l u e b e l l c u r v e o f Andrew and o t h e r s (1985) a l s o shown. 0.0 Ma 15.7 H 15.6 H Shale Curve 0.50 0.25 0.25 0.0 Ma 15.5 -\ 0.50 Bluebell Curve 15.4 — i 1 19.5 20. 17.5 18.0 18.5 206 19.0 p b / 2 0 4 P b F i g u r e 4 - 9 . Su1 p h i d e - 1 e a d p l o t of * ° B P b / ! ° ' P b vs ' ° 6 P b / ! ° * P b d a t a f r o m T a b l e s 4 - 2 b , 4 -3 and 4 - 4 . Symbols as d e s c r i b e d i n F i g u r e 4 - 8 . The g r o w t h c u r v e s shown a r e s h a l e c u r v e (Godwin and S i n c l a i r , 1982) and B l u e b e l l c u r v e (Andrew et a / . , 1985) . 1 55 and 165 Ma. The d a t a i n d i c a t e a h i g h e r u s o u r c e f o r these lower sediments (1 km e a s t of Nakusp, BC). T h i s suggests N o r t h American c o n t i n e n t a l d e r i v a t i o n f o r a t l e a s t p a r t of the l e a d . T a b l e 4-2a p r e s e n t s t h o r i u m , uranium and l e a d abundances f o r s i x sediment samples from the st u d y a r e a . C a l c u l a t e d i t - v a l u e s v a r y d r a m a t i c a l l y f o r d i f f e r e n t l i t h o l o g i c a l u n i t s . The low u and W-values f o r sample 1708 r e f l e c t lower U and Th and p r o b a b l y l e a d a d d i t i o n r e l a t e d t o m i n e r a l i z a t i o n . A l t h o u g h the 2 0 7 P b / 2 0 , P b i s h i g h e r , the mean 2 o s p b / 2 0 4 p b v a i u e c o r r e c t e d f o r 247 Ma (T a b l e 4-2B) c o r r e s p o n d s remarkably w e l l w i t h the f r a m b o i d mean ( F r ) on both F i g u r e . 4-8 and F i g u r e 4-9. ( F r ) a l s o l i e s on the 225 Ma m i x i n g i s o c h r o n of Andrew and o t h e r s (1985). A growth c u r v e has been g e n e r a t e d (from the s u l p h i d e i s o t o p i c d ata) t o d e s c r i b e l e a d e v o l u t i o n w i t h i n the upper S l o c a n Group sediments. G e n e r a t i o n of the c u r v e assumes: 1) d e p a r t u r e from Stacey and Kramers (1975) c u r v e a t the same p o i n t as the s h a l e cu^ve of Godwin and S i n c l a i r , (1982; i . e . a t 1890 Ma); and 2) the mean fr a m b o i d ( F r ) r e p r e s e n t s i s o t o p i c c o m p o s i t i o n ( x t 3 , y t 3 ) a t 225 Ma. A c c o r d i n g t o the r e l a t i o n s h i p : x t = a 0 + vi(e 1 -e 1 l) + uz(s  1 l-e 1 z ) + U3 (e 1 z - e ^ 3) y t = b D + ^ _ ( e X 2 T - e X 2 t l ) . + _ U a _ ( e * 2 t i _ e X 2 t 2 j +  L 3 137188 137.88 ( e ^ 2 t 2 . e X 2 t 3 ) 7 .88 156 M 3 can be c a l c u l a t e d . The 225 Ma i s o c h r o n c a l c u l a t e d from 1890 Ma i n t e r s e c t s F r w i t h i n one s t a n d a r d d e v i a t i o n of the mean. E q u a t i o n s 2 and 3 g i v e apparent t h i r d s tage M-values of 11.12 and 10.07 u s i n g ( x t 3 ) or ( y t 3 ) r e s p e c t i v e l y . Sediment 2 0 6 P b / 2 C M , P b r a t i o s a t the time of m i n e r a l i z a t i o n ( t 3 = 165 Ma) a r e 18.68 f o r the upper sediments (assuming M = 11.12) and 18.74 f o r whole-rock d a t a from Ghosh (1985, p e r s . comm.) ( t 3 = 165 Ma). These c o r r e s p o n d e x c e e d i n g l y w e l l t o the 2 0 6 P b / 2 0 a P b v a l u e of v e i n (Vn) l e a d s ( F i g . 4-8). S l o c a n v e i n l e a d s (Table 4-3) p l o t both below the s h a l e c u r v e and lower S l o c a n whole-rock l e a d i s o t o p e d a t a , and s t r a d d l e the l i n e a r a r r a y d e f i n e d by upper S l o c a n p y r i t e d a t a ( F i g . 4-8). The mean (n = 31, Vn) c o i n c i d e s c l o s e l y w i t h t h i s l i n e a r t r e n d s i t u a t e d midway between the i n i t i a l s e d i m e n t a r y r a t i o d e f i n e d by average framboids ( F r ) and the average metamorphic c l u s t e r (Mm). Assuming a s t r i c t s e d i m e n t a r y s o u r c e i n i t i a l c o m p o s i t i o n a t ( F r ) , t , = 225 Ma, and t 2 = 154 t o 166 Ma ( i . e . 160 ± 6 Ma), the range of M-values n e c e s s a r y t o e v o l v e from ( F r ) t o the mean of the v e i n (Vn) d e p o s i t s a r e 17.6 t o 20.0. Higher than the s h a l e c u r v e (M = 12.2), t h i s v a l u e i s not unr e a s o n a b l e and compares r e a s o n a b l y w i t h c a l c u l a t e d v a l u e s (Table 4-2). F i g u r e 4-10 shows the d e n s i t y d i s t r i b u t i o n of M-values from T a b l e s 4-2A and 4-2B. Lead i s o t o p i c a n a l y s i s of f e l d s p a r c o n c e n t r a t e s (Table 4-4) from the N e l s o n b a t h o l i t h (Reynolds and S i n c l a i r , 1971) 1 5 7 T a b l e 4 - 3 G a l e n a l e a d I s o t o p e r a t i o s f o r v e i n d e p o s i t s ( L e C o u t e u r , 1973; Andrew e t a l . , 1985) Lead i s o t o p e r a t i o s L a t Long D e p o s 1 t name n o r t h west 206 Pb/204 Pb 207 Pb/204 Pb 208 Pb/204 A r l i n g t o n - 49 . .79 117, .36 18, .846 15, .639 39. ,026 B o s u n 49 . .97 117 .36 18 .736 15 .625 39. ,019 C h a p l e a u 49. .74 117, .39 19, . 136 15, .671 38 .908 C a l i f o r n l a 49 .98 117 .32 18, .619 15, .610 39 ,035 C o r k P r o v i n c e 49 . .91 117, .07 18, .789 15, .627 39. .021 C o r o n a t i o n 49 . .82 1 17, .43 18, .964 15, .649 38 .946 D u b l i n Queen 50, .00 1 17. . 17 18 .748 15, .631 39. .012 E n t e r p r 1 s e 49. .82 117 .33 18 .717 15 .627 38, .951 F i s h e r M a i d e n 49 , .91 117, .21 18 , .739 15, .626 38 ,995 Index 49, .86 117, . 13 18 , . 757 15, .641 38 .940 I v a n h o e 49, .95 117, .24 18 .743 15 .636 39, .001 K a l i s p e l 1 49, .86 117 .41 18 .701 15 .624 38 .952 L u c k y J1m 50 .03 117 .20 18 .773 15 .625 39 .012 L i t t l e Tim 49, .81 1 17, .37 18 .810 15 .633 39. . 135 M o l 1 y Hughes 50, .01 117, .38 18, .918 15 .656 38 .728 N o b l e 5 49, .99 117, .20 18 .893 15 .656 39 .025 Payne 50 .01 1 17 .23 18 .740 15 .625 39 .030 R u t h - H o p e 49, .97 1 17 .23 18 .699 15 .623 38 .998 U t l c a 49, .98 117, . 13 18, .785 15 .632 38 .991 V i c t o r 50, .OO 117 .27 18 .715 15 .616 38 .976 Van R o i 49, .93 117, .29 18, .708 15, .639 39 .033 V u l t u r e 49, .98 117, . 16 18, . 704 15 .620 39 .012 Wh1tewater 50, .04 117 . 13 18 .795 15 .648 38 .825 S 1 I v e r s m l t h 49, ,97 117, .22 18, .721 15 .641 39 .051 S i l v e r L e a f 49 . .86 1 17, .32 18, .626 15, .606 38 ^913 S t a n d a r d 49, 96 117, .32 18, .664 15, .627 39 .006 K o o t e n a y B e l 1 50, .00 1 17, .06 18 .884 (0 . .06) 15 .725 ( 0 . 15) 38 .639 S c r a n t o n 49 . .79 117 .06 18 .884 15 .653 38 .696 H e w i t t - S i I v e r t o n 49. .93 117, .31 18 .680 (0 . .08) 15 .577 ( 0 . 17) 38 .890 S y 1 v a n n a 50, .05 1 17 .30 18, .712 (0 , .02) 15 .621 ( 0 . 03) 38 .992 O t t a w a 49, .79 117 .40 18 .873 15 .634 39 .052 A r i t h m e t i c mean (X) = 18 .777 15 .634 38 .961 S t a n d a r d d e v i a t i o n (S ) = 0 . 109 0 .024 0 . 108 S t a n d a r d e r r o r , o f mean (SxnVJ) = 0. .020 0 .004 0 .019 T a b l e 4 -4 L e a d i s o t o p e r a t i o s f o r K - f e l d s p a r f rom t h e N e l s o n b a t h o l i t h ( R e y n o l d s and S i n c l a i r , 1971) SAMPLE L a t Long DESCRIPTION LEAD ISOTOPE RATIOS n o r t h west Pb 206/204 207/204 208/204 (ppm) R-14 4 9 . 5 2 117.24 R - 3 4 9 . 2 9 117 .23 R - 1 0 4 9 . 4 8 116 .50 p o r p h y r i t i c g r a n i t e 50 p o r p h y r l t i c q u a r t z 40 monzoni t e p e g m a t i t e a s s o c i a t e d 30 w i t h f o l i a t e d d l o n t e 19 .330 15.657 3 8 . 9 0 3 18.942 15 .602 38 .601 19.152 15 .660 39 .039 R-9 4 9 . 3 8 117.05 p o r p h y r i t i c g r a n i t e 40 18.932 15.557 38 .636 158 i n d i c a t e i t s composite n a t u r e and inhomogeneous c h a r a c t e r ( F i g . 4-8). The f e l d s p a r d a t a p l o t w i t h n e g a t i v e model ages ( w i t h r e s p e c t t o the s h a l e c u r v e ) i n d i c a t i n g i n s i t u uranium decay. The two samples from w i t h i n the s t u d y a r e a (R-10 and R-14) p l o t c l o s e t o the s e d i m e n t a r y s u l p h i d e l e a d l i n e and a r e c o n s i s t e n t w i t h an e v o l u t i o n by r a d i o g e n i c a d d i t i o n from a source s i m i l i a r t o the s u l p h i d e s . Samples (R-3 and R-9, l o c a t e d near N e l s o n , B.C.) are d e p l e t e d i n r a d i o g e n i c l e a d ( 2 0 6 P b / 2 0 * P b ) w i t h r e s p e c t t o the upper c r u s t . The l a r g e i s o t o p e v a r i a t i o n among the samples i s l i k e l y r e l a t e d t o the s e p a r a t e i n t r u s i v e , u p l i f t and c o o l i n g h i s t o r i e s ( H a r r i s o n , 1985) f o r the two g e o g r a p h i c a l l y s e p a r a t e a r e a s . The b a t h o l i t h i s e n r i c h e d i n 2 0 6 P b / 2 0 " P b , has low 2 0 7 p B / 2 0 a p B a n d 2 0 8 p b / 2 0 4 p b a n ( J c a n fae g h o w n f r o m i n i t i a l s t r o n t i u m r a t i o s (from 0.705 t o 0.707, Duncan, 1982; Duncan et al . , 1979) t o d e r i v e p r o b a b l y from the upper mantle or lower c r u s t (Andrew et al . , 1985). The upper m a n t l e / l o w e r c r u s t i s c h a r a c t e r i z e d by low U/Pb r a t i o s and h i g h Th/U r a t i o s (Doe and Zartman, 1979). P l o t s of 2 0 8 P b / 2 0 4 P b v s . 2 0 6 P b / 2 0 4 P b ( F i g . 4-9) show the same i s o t o p e c o m p o s i t i o n f o r metasedimentary s u l p h i d e s (Mm) and N e l s o n b a t h o l i t h samples (R-3 and R-9). The more r a d i o g e n i c samples (R-14 and R-10) a r e f u r t h e r d i s p l a c e d t o the r i g h t . The c o i n c i d e n c e of i s o t o p i c c o m p o s i t i o n and age of f o r m a t i o n of b a t h o l i t h and metamorphic s u l p h i d e s i s s u f f i c e n t i n s o f a r as assuming a mean 2 0 6 P b / 2 0 , P b v a l u e r e p r e s e n t a t i v e of the b a t h o l i t h a t i t s time of emplacement. >-o z HI ZD o LU fX LU 5 i 4 -3 -2 -10 15 //-VALUES F i g u r e 4-10. Histogram of c a l c u l a t e d u - v a l u e s , from T a b l e s 4-2A and 4-2B. B . I . i s c l a s s i n t e r v a l , N i s sample s i z e . 160 A 2 0 6 P b / 2 0 , , P b r a t i o of 18.91 f o r the b a t h o l i t h i s more r a d i o g e n i c than e i t h e r of the s e d i m e n t a r y v a l u e s . From the o b s e r v e d v e i n d e p o s i t 2 0 6 P b / 2 0 " P b v a l u e s , s i m p l e c a l c u l a t i o n s i n d i c a t e p o s s i b l e m i x i n g p r o p o r t i o n s of l e a s t r a d i o g e n i c s e d i m e n t a r y l e a d (18.68) and b a t h o l i t h l e a d (18.91). E s t i m a t e s of the r a d i o g e n i c c o n t r i b u t i o n n e c e s s a r y from the b a t h o l i t h , t o produce the observed v e i n 2 0 6 P b / 2 0 * P b v a l u e s range from 0.0 t o 90 p e r c e n t of the t o t a l 2 0 6 P b / 2 0 f t P b . V e i n d e p o s i t s (Vn) a r e e n r i c h e d i n t h o r o g e n i c ( 2 0 8 P b ) r e l a t i v e t o u r a n o g e n i c ( 2 0 7 P b and 2 0 6 P b ) l e a d . A l l measured d a t a p l o t below the s h a l e c u r v e and would seem t o p r e c l u d e a s i m p l e m i x i n g of B l u e b e l l - t y p e and S h a l e - t y p e l e a d ( F i g . 4-9). A s l i g h t s h i f t of the l e a s t r a d i o g e n i c sample e i t h e r upwards or t o t h e l e f t between e i t h e r bounds of measurement e r r o r would p l a c e the p o i n t between the two c u r v e s and i n d i c a t e a l a r g e l y c r u s t a l component t o the r e s i d u e l e a d . One p o s s i b l e e x p l a n a t i o n i s t h a t none of the r e s i d u e samples, t r u l y r e p r e s e n t the o r i g i n a l average l e a d i n S l o c a n Group a t time of d e p o s i t i o n , but c o n t a i n a t l e a s t a s m a l l component of r a d i o g e n i c a d d i t i o n not removed by l e a c h i n g . 4.9 CONCLUSIONS Lead i s o t o p e d a t a from s y n - s e d i m e n t a r y s u l p h i d e s i n the L a t e T r i a s s i c S l o c a n Group suggest t h a t l e a d and perhaps s i l v e r , z i n c and g o l d , i n e p i g e n e t i c v e i n s was e x t r a c t e d 161 from the s edimentary package d u r i n g emplacement of the L a t e J u r a s s i c N e l s o n b a t h o l i t h . Sedimentary s u l p h i d e l e a d i s o t o p e s p l o t w i t h i n the p e l a g i c f i e l d and r e p r e s e n t orogene l e a d . The i n t e r m e d i a t e p o s i t i o n of the s u l p h i d e d a t a p r e c l u d e s m i x i n g of two end-member r e s e r v o i r s ( i . e . S h a l e - c u r v e , upper c r u s t a l and B l u e b e l l c u r v e , lower c r u s t a l , Andrew et al. , 1985). Rather a s i m p l e e v o l u t i o n a r y p a t h s t a r t i n g a t 1.9 Ga and e v o l v i n g w i t h /x= 11.12 c o u l d have g e n e r a t e d the r e q u i r e d 2 0 6 P b / 2 0 4 P b r a t i o s t o form the d e p o s i t s a t t 3 = 160 ± 6 Ma. A d d i t i o n a l , upper c r u s t a l g e n e r a t e d t h o r i u m 2 0 8 P b i s a l s o r e q u i r e d t o produce the observed v e i n d e p o s i t l e a d v a l u e s . A d d i t i o n s t o s e d i m e n t a r y l e a d of r a d i o g e n i c l e a d from a b a t h o l i t h i c source cannot be r u l e d o u t . B a t h o l i t h i c - h o s t e d 'dry' ore d e p o s i t s ( C a i r n e s , 1934) have 015% h i g h e r 2 0 6 P b / 2 O * P b r a t i o s than the 'wet' s e d i m e n t - h o s t e d d e p o s i t s . Ongoing m i n e r a l i z a t i o n , p o s t d a t i n g the main event and s c a v e n g i n g r a d i o g e n i c l e a d i s the p r e f e r r e d e x p l a n a t i o n . The c o n c e n t r i c 2 0 6 P b / 2 0 , P b z o n a t i o n p a t t e r n ( L e C o u t e u r , 1973) r e f l e c t s the i s o t o p i c s i g n a t u r e of the s e d i m e n t a r y h o s t . L e a s t r a d i o g e n i c v a l u e s occupy the upper u n i t s and more r a d i o g e n i c the lower l i t h o l o g i c a l u n i t s , s u p p o r t i n g e x t r a c t i o n of s e d i m e n t a r y l e a d . REFERENCES CITED Andrew, A., Godwin, C.I. and S i n c l a i r , A . J . 1984. M i x i n g l i n e i s o c h r o n s : a new i n t e r p r e t a t i o n of g a l e n a l e a d i s o t o p e d a t a from s o u t h e a s t e r n B r i t i s h Columbia. Economic Geology, 79, pp. 919-932. Armstrong, R. L. 1982. L a t e T r i a s s i c - E a r l y J u r a s s i c t ime s c a l e c a l i b r a t i o n i n B r i t i s h C olumbia, Canada, i n O d i n , G. S., ed., N u m e r i c a l d a t i n g i n s t r a t i g r a p h y , New York, John W i l e y and Sons. pp. 509-513. Brame, S. 1979. M i n e r a l i s a t i o n near the n o r t h e r n margin of the N e l s o n B a t h o l i t h . M.Sc. t h e s i s , U n i v e r s i t y of A l b e r t a , Edm., 146 p. B r e v a r t , 0., Dupre , B. and A l l e g r e , C.J. 1982. M e t a l l o g e n i c p r o v i n c e s and the r e m o b i l i z a t i o n p r o c e s s s t u d i e d by l e a d i s o t o p e s : l e a d - z i n c ore d e p o s i t s from the s o u t h e r n M a s s i f c e n t r a l F r a n c e . Economic Geology, 77, pp. 564-575. C a i r n e s , C. E. 1934. S l o c a n m i n i n g camp, B r i t i s h C olumbia. G e o l o g i c a l Survey of Canada, Memoir 173, 137 p. Cauet, S. and Weiss, D. 1983. Lead i s o t o p e s t u d y of a l e a d - z i n c v e i n m i n e r a l i z a t i o n and i t s h o s t s e d i m e n t s , Heure, Belgium: b a s i s f o r a g e n e t i c model. Economic Geology, 78, pp. 1011-1016. Cox, J . 1979. The geology of the northwest margin of the N e l s o n b a t h o l i t h , B r i t i s h C olumbia. M.Sc. t h e s i s , U n i v e r s i t y of A l b e r t a , Edm., 95 p. Doe, B.R. and Zartman, R.E. 1979. P l u m b o t e c t o n i c s , the P h a n e r o z o i c , i n B arnes, H. L., ed., G e o c h e m i s t r y of h y d r o t h e r m a l ore d e p o s i t s . New York, John W i l e y and Sons, pp.22-70. Duncan, I . J . and P a r r i s h , R. R. 1979. Geochronology and s t r o n t i u m i s o t o p e g e o c h e m i s t r y of the N e l s o n b a t h o l i t h : a p o s t - t e c t o n i c i n t r u s i v e complex i n s o u t h e a s t B r i t i s h C o lumbia. G e o l o g i c a l S o c i e t y of A m e r i c a , A b s t r a c t s w i t h Programs, 11, p.76. Duncan, I . J . , P a r r i s h , R. R. and Armstrong, R. L. 1979. Rb/Sr geochronology of the p o s t - t e c t o n i c i n t r u s i v e e v e n t s i n the Omineca C r y s t a l l i n e B e l t , s o u t h e a s t e r n B r i t i s h Columbia ( a b s t r a c t ) . C o r d i l l e r a n S e c t i o n of the G e o l o g i c a l A s s o c i a t i o n of Canada, Vancouver, B.C., Program and A b s t r a c t s , p.15 Duncan, I . J . 1982. The e v o l u t i o n of the Thor-Odin g n e i s s dome and r e l a t e d g e o c h r o n o l o g i c a l s t u d i e s , u n p u b l i s h e d 162 1 63 Ph.D. t h e s i s , U n i v e r s i t y of B r i t i s h C olumbia, Van., 353 p. C o l u m b i a , Van., 86 p. F y l e s , J.T. 1967. Geology of the A i n s w o r t h - K a s l o a r e a , B r i t i s h C olumbia. B r i t i s h Columbia Department of Mines and P e t r o l e u m Resources. B u l l e t i n 53, 125 p. Ghosh, D. and Lambert, R. St J . 1983. Lead i s o t o p e s i n sediments and b a t h o l i t h s from the Nelson-Salmo a r e a , s o u t h e a s t B r i t i s h C olumbia, i n G e o l o g i c a l A s s o c i a t i o n Canada, M i n e r a l o g i c a l A s s o c i a t i o n Canada, and Canadian G e o p h y s i c a l Union J o i n t meeting V i c t o r i a , 8, p. Godwin, C. I . and S i n c l a i r , A. J . 1982. Average l e a d i s o t o p e growth c u r v e s f o r s h a l e - h o s t e d z i n c - l e a d d e p o s i t s , Canadian C o r d i l l e r a . Economic Geology, 77, pp. 675-690. Godwin, C. I . , S i n c l a i r , A. J . and Ryan, B. D. 1982. Lead i s o t o p e models f o r the g e n e s i s of c a r b o n a t e - h o s t e d Zn-Pb, s h a l e h o s t e d Ba- Zn-Pb, and s i l v e r - r i c h d e p o s i t s i n the n o r t h e r n . C a n a d i a n C o r d i l l e r a . Economic Geology, 77,pp.82-94. H a r r i s o n , T. M. 1985. Thermal h i s t o r y of the N e l s o n b a t h o l i t h , B r i t i s h C olumbia. G e o l o g i c a l A s s o c i a t i o n of A m e r i c a , C o r d i l l e r a n S e c t i o n , Program and A b s t r a c t s , Vancouver M e e t i n g , p. 360 Hedley, M. S. 1952. Geology and o r e d e p o s i t s of the Sandon a r e a , S l o c a n m i n i n g camp, B r i t i s h C olumbia. B r i t i s h Columbia Department of Mines and P e t r o l e u m R e s o u r c e s , B u l l e t i n 29, 130 p. L e C o t e u r , P. C. 1973. A s t u d y of l e a d i s o t o p e s from m i n e r a l d e p o s i t s i n s o u t h e a s t e r n B r i t i s h Columbia and i n the A n v i l Range, Yukon T e r r i t o r y . Ph.D. T h e s i s , 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 B r i t i s h C o lumbia, Van., 142 p. L e w i s , T. 1974. Heat p r o d u c t i o n measurement i n r o c k s u s i n g a gamma ra y s p e c t r o m e t e r w i t h a s o l i d s t a t e d e c t o r . Canadian J o u r n a l of E a r t h S c i e n c e s , 11, pp. 526-532. Monger, J . W. H., P r i c e , R. A. and Templeman-Kluit, A. J . 1982. T e c t o n i c a c c r e t i o n and the o r i g i n of the two major metamorphic and p l u t o n i c w e l t s i n the Canadian C o r d i l l e r a . Geology, 10, pp. 70-75. Nguyen, K. K., S i n c l a i r , A. J . and L i b b y , W. G. 1968. Age of the n o r t h e r n p a r t of the N e l s o n b a t h o l i t h . Canadian J o u r n a l of E a r t h S c i e n c e s , 5, pp. 955-957. O r c h a r d , M. J . 1985. C a r b o n i f e r o u s , Permian and T r i a s s i c conodants from the c e n t r a l Kootenay A r c : c o n s t r a i n t s on 1 64 the age of the M i l f o r d , K a s l o and S l o c a n Groups, i n C u r r e n t R e s e a r c h , P a r t A, G e o l o g i c a l Survey of Canada, Paper 85-1A, pp. 287-300. R e y n o l d s , P. H. and S i n c l a i r , A. J . 1971. Rock and o r e - l e a d i s o t o p e s from the N e l s o n b a t h o l i t h and the Kootenay A r c , B r i t i s h C o lumbia, Canada. Economic Geology, 66, pp. 259-266. S i n c l a i r , A. J . 1967. Trend s u r f a c e a n a l y s i s of minor elements i n s u l p h i d e s of the S l o c a n m i n i n g camp, B r i t i s h C olumbia, Canada. Economic Geology, 62, pp. 1095-1101. S i n c l a i r , A. J . 1979. P r e l i m i n a r y e v a l u a t i o n of summary p r o d u c t i o n s t a t i s t i c s and l o c a t i o n d a t a f o r v e i n d e p o s i t s , S l o c a n , A i n s w o r t h , and S l o c a n C i t y camps, so u t h e r n B r i t i s h C olumbia, i n C u r r e n t R e s e a r c h , P a r t B, G e o l o g i c a l Survey of Canada, Paper 79-1B, pp. 173-178. S t a c e y , J . S. and Kramers, J . D. 1975.Approximation of t e r r e s t i a l l e a d i s o t o p e e v o l u t i o n by a two-stage model. E a r t h and P l a n e t a r y S c i e n c e L e t t e r s , 26, pp. 207-221. Wampler, J . M. and K u l p , J . L. 1964. An i s o t o p i c s t u d y of l e a d i n s e d i m e n t a r y p y r i t e . Geochimica e t Cosmochimica A c t a , 28, pp. 1419-1458. 5. CONCLUSIONS In t e s t i n g whether Ag-Pb and Zn i n v e i n d e p o s i t s c o u l d have o r i g i n a t e d from the e n c l o s i n g s ediments, a d d i t i o n a l f a c t o r s r e l a t e d t o ore d e p o s i t i o n ( i . e . t r a n s p o r t a t i o n and d e p o s i t i o n of m e t a l s ) have been a s c r i b e d t o i n t r u s i o n of the N e l s o n b a t h o l i t h . A f i r s t a p p r o x i m a t i o n c o o l i n g h i s t o r y f o r the 160 Ma Nels o n b a t h o l i t h s u g g e s t s an e q u i v a l e n t age f o r m i n e r a l i z a t i o n , based on e a r l i e r f l u i d i n c l u s i o n , and S and P b - i s o t o p e s t u d i e s . L i t h o g e o c h e m i c a l l e v e l s of Pb and Zn a r e not a p p r e c i a b l y e l e v a t e d i n the S l o c a n Group above average s h a l e v a l u e s . N e i t h e r a r e v a l u e s from the R o s s l a n d Group s t r a t a . Ag, Ba and S a r e e n r i c h e d i n the S l a t e b e l t , a h o r i z o n w i t h i n the S l o c a n Group which c o n t a i n s s y n / s e d i m e n t a r y base m e t a l s u l p h i d e s . T h i s u n i t / z o n e b i s e c t s the a r e a (Sandon) which c o n t a i n s the h i g h e s t c o n c e n t r a t i o n of d e p o s i t s w i t h i n the S l o c a n camp and may have a c t e d as a so u r c e bed. Source rock volume c a l c u l a t i o n s f o r t o t a l camp p r o d u c t i o n a r e not u n r e a s o n a b l e and c o m p a t i b l e w i t h the S l a t e b e l t as a s o u r c e . P b - i s o t o p e s t u d i e s have e s t a b l i s h e d i n i t i a l i s o t o p e r a t i o s arid ju-values f o r the Upper T r i a s s i c age of s e d i m e n t a t i o n . V e i n d e p o s i t P b - i s o t o p e s occupy a l a t e M i d d l e J u r a s s i c p o s i t i o n on the ' S l o c a n ' e v o l u t i o n c u r v e which s u g g e s t s the 160 ± 6 Ma N e l s o n b a t h o l i t h a c t e d as the heat s o u r c e t o c i r c u l a t e m i n e r a l i z i n g f l u i d s . The Pb i s o t o p e c o m p o s i t i o n of the sediments a t the time of v e i n f o r m a t i o n i n d i c a t e t h a t Pb and p o s s i b l y Zn and Ag were d e r i v e d from a 165 166 se d i m e n t a r y s o u r c e . V e i n m e t a l z o n a t i o n has been sh'own t o be r e l a t e d t o maintance of open s t r u c t u r e s d u r i n g f l o w of m i n e r a l i z i n g f l u i d s . T h i s t o g e t h e r w i t h the v e i n m i n e r a l p a r a g e n e s i s s u g g e s t s t h a t l o d e s h o s t i n g 'wet' o r e s formed p r i o r t o those which host 'dry' o r e s . 'Dry' o r e s a r e c o n f i n e d almost e x c l u s i v e l y t o the b a t h o l i t h . T h i s l e a d s t o the h y p o t h e s i s t h a t : 1) s t r u c t u r e s w i t h i n the b a t h o l i t h were not open t o e a r l y Pb, Z n - r i c h f l u i d s , or 2) f l u i d c i r c u l a t i o n s e t up around the p l u t o n r e a c t e d d i f f e r e n t l y i n a d j u s t i n g t o igneous v s . s e d i m e n t a r y w a l l r o c k d u r i n g m i g r a t i o n a l o n g r e s p e c t i v e f l o w p a t h s . The s l i g h t l y more r a d i o g e n i c n a t u r e of b a t h o l i t h - h o s t e d 'dry' d e p o s i t s f a v o u r s the f i r s t p o s t u l a t i o n , t h a t of a l a t e r age. Thus e s t a b l i s h i n g b oth t y p e s of ore ('wet' and 'dry') as fo r m i n g a t s p e c i f i c s t a g e s d u r i n g a continuum of m i n e r a l i z a t i o n . APPENDIX A Assay co-ordinates, metal concentrations, and sample width for 1) Hangingwall vein 2) Footwall vein and 3) wallrock for Hallmac Mine, Sandon, B.C. HANGINGWALL SAMP NUM X-AXIS EAST(m) Y-AXIS NORTH(m) Z-AXIS ELEV(m) AG ( o / t ) PB (%) ZN (%) CU ('/.) AU ( o / t ) WIDTH ( m ) 1651 5730. .4 5742 .6 1731 . 1 20 .47 16 .0 1 .09 .0000 0 .01 1 0. 33 1652 5728. . 3 5743, .7 1731 . 5 58 . 12 22 .5 1 .38 .0000 0 .010 0. .40 1653 5729 .4 5744 . 4 1731 . 4 5 .83 2 . 23 1' .51 . 1690 0 .005 0. . 76 1654 5728 , 3 5745 .0 1731 . 4 104 .0 25 . 4 1 .92 .0000 0 .006 0. .48 . 1655 5729. .2 5745, .0 1731 . 4 14 .70 3 .46 1 .89 . 1760 0 .015 0 30 1656 5733. 2 5741 . 1 '1731 .5 5. , 1 1 1 . 29 - 1 .69 .0000 0 .007 0 .45 1657 5733. .2 5741 .5 1731 .5 1 . 47 0 . 549 1 . 20 .0000 0 .004 0 44 1658 5735, .2 5741 .4 1731 .6 58 .61 16 .8 1 .37 .0000 0 .022 0 50 1659 5740 .3 5741 .6 1731 .5 10 .33 1 .63 1 .66 .0000 0 .0 0 .90 6317 5736, ,7 5741 , 4 1731 . 6 34 ,0 11 . 15 1 .65 .0000 0 .0 0. .90 1676 5728 . 1 5740 8 1731 8 ° 8, ,03 2 .20 0 ,589 .0000 0 .004 0. . 4 1 1677 5728, . 1 5741 .3 1731 .8 7 .09 3 .94 0 .625 . 1 140 0 .035 0, , 20 1678 5728 . 1 5741 .6 1731 . 8 10 .62 1 1 . 1 0 .557 .0000 0 .047 0 . 30 1679 5728 . 1 5741 8 1731 .8 10 .66 13 . 5 0 .555 . 1 100 0 . 127 0 , 20 1680 5728, . 1 5742 . 1 1731 8 10 ,95 5 .83 0. .922 .0000 0 .019 0 40 1681 5727, ,2 5740 8 1731 .5 135 .48 37 .5 0. .644 . 2000 0 .043 0, .20 1682 5727, .2 5741 .2 1731 .5 15 ,72 4 .63 0 . 322 .0000 0 .006 0 .50 1683 5727 .2 5741 . 7 1731 ,5 10 .52 3 .06 0 .780 .0000 0 .018 0. .50 1684 5730 . 1 5740 .9 1731 .8 1 . 77 3 .21 0 .500 .0000 0 .0 0 20 1660 5728 . 7 5737 . 1 1727 .3 15 .03 3 . 16 0 . 250 .0250 0 .013 0 .50 1661 5728)7 5737 . 4 1727 . 3 106 . 15 44 . 1 0 .920 .0000 0 .045 0. 13 1662 5728. .7 5737 .6 1727 .3 7 .37 1 .09 1 .90 .0775 0 ; o i 1 0. 25 1665 5750, . 1 5739 .4 1727 , 4 1 16 . 17 30 . 7 1 . 75 .5150 0 .017 0. 35 1666 5750, . 1 5738 .9 1727 .4 1 .05 0 . 187 0 . 1 18 .0052 0 .003 0. 60 1687 5735 8 5738 .0 1727 . 1 17 .67 4 . 57 2 . 44 . 1520 0 .009 0. .75 1688 5735 , 8 5738 .5 1727 , 1 57 . 70 23 . 3 t . 46 . 1650 0 .011 0. 30 1690 5733 , ,9 5737 . 8 1727 . 3 19 .07 2 .61 1 .94 . 1040 0 .006 0. 50 1691 5733 .9 5738 . 2 1727 . 3 5 1 .94 18 . 7 2 . 59 . 1630 0 .015 0. , 25 1692 5733 .9 5738 .5 1727 . 3 2 .95 0 .416 0 .622 .0079 0 .010 0 40 1693 5730 .8 5737 . 8 1727 . 4 6 .06 3 .57 1 . 48 .0875 0 .010 b , 45 1694 5730 .8 5738 . 2 1727 . 4 65 .96 27 .8 1 . 36 .2140 0 . 1 18 0 . 20 1695 5730, .8 5738 .6 1727 , 7 7 . 29 1 . 36 1 .40 .0000 0 .005 0. .60 1696 5744 . 2 5738 . 3 1727 . 7 16 .01 7 .49 3 . 10 .0445 0 .005 0 . 40 1697 5744 .2 5738 .8 1727 .7 0 .96 5 .03 1 . 4 1 .0665 0 .0 0, . 30 1698 5744 . 2 5739 . 2 1727 . 7 21 . 18 7 .77 0 .929 . 1670 0 .008 0. .90 6315 5743 . 1 5738 . 2 1725 .4 1 10 .0 32 .59 1 .65 .0000 0 .0 0, .84 6316 5737, 8 5738 . 1 1725. .2 63 ,0 19 .83 1. .70 .0000 0 .0 0, 63 6314 5736, .2 5736 8 1722 .2 43 ,0 15 .65 1 .91 .0000 0 .0 0. .99 6313 5737, .7 5736 .9 1722 .0 17 .0 4 . 29 0 . 93 .0000 0 .0 0 .93 6309 5746, ,2 5736 . 9 1722 .5 1 . 2 0 .32 0 .93 .0000 0 .0 1. 20 6308 5748 ,o 5736 .8 1722 .6 2 . 2 0 . 59 0 . 57 .0000 0 .0 0 .80 6312 5736. ,0 5735, . 5 1720. .2 19 . 4 2 . 25 0. 88 .0000 0 .0 0. 96 1673 5740. , 7 5734 .6 1720. .0 1 .28 0 . 320 0. 534 .0177 0 .004 0 75 1674 5740 .8 5735 . 1 1720 .0 17 . 19 1 . 46 0 . 442 .0750 0 .019 0 35 1675 5740 8 5735 .5 1720. .0 3 .07 1 .04 0 . 423 .0295 0 .0 0. 26 1711 5742 . 3 5734 .8 1719 .6 4 .67 0 . 535 0 .786 .0475 0 .0 0 . 35 1710 5742 . 3 5734 . 3 17 19 .6 2 .88 0 .910 0 .590 .0188 0 .0 0 , 55 1709 5745 .6 5734 .9 1719. . 7 10 . 42 1 .05 0 .812 .0700 0 .006 0. 75 1708 5745 . 7 5734 . 3 17 19 . 7 107 , .08 21 . 3 1 .06 . 2730 0 .036 0. 40 1707 5745 .8 5733 . 7 1719. . 7 134, .28 33 .9 1 . 47 . 3300 0. .026 0. 75 1706 5748 .0 5735 . 1 1719 , 3 6 .29 3 .06 0 . 296 .0280 0. ,0 0. 75 1705 5748 .0 5734 .6 1719 . 3 10 , 23 4 .01 0 .867 . 1690 0. ,0 0. 50 1704 5749. .9 5735 . 2 1719 , 1 20 .53 13 . 5 0 . 549 .0420 o. ,007 0. 50 1703 5750 .0 5734 . 7 1719 . 1 50 . 36 19 . 1 , 0 ,840 . 1015 0. ,0 0. 40 1702 5752 .0 5735 .2 1719 . 3 7 .80 1 .69 0 ,737 .0710 0. .0 0. 50 1701 5752. 1 5734 . 9 1719. 3 43 . 09 15 . 7 1. 42 . 1330 0. 0 0. 30 1700 5754 . 0 5735 . 1 1719. 2 19 . 04 7 . 86 0. 86 . 1 170 0. 0 0. 55 1699 5753. 9 5735 . .4 1719. 2 187 . 25 44 . 1 0. 247 . 1260 0. 017 0. 35 1663 5756 . 6 5736 0- 17 18. 5 1 10. 24 26 . 9 0. 898 .3150 0. 020 0. 15 1669 5756, .7 5735. 6 17 18. 5 2 . 3 1 1 . 01 0. 698 .0550 0. 0 0. 55 1670 5756. 8 5735. . 3 1718 .5 20, ,50 9 . 33 1. 58 . 1770 0. 004 0. 15 167 1 68 FOOTWALL SAMP X - A X I S Y - A X I S Z - A X I S AG NUM EAST(m) NORTH(m) ELEV(m) ( o / t ) 3926B 5757 .5 5747 . 5 1739 . 2 84 .98 3927B 5758 .8 5747 .8 1740 .4 38 .35 3928B 5795 .7 5755 .0 1741 .0 13 .05 3929B 5797 .4 5755 .7 1744 .5 57 .97 3930B 5800 .4 5755 .5 1744 .5 45 .74 3931B 5768 .8 5750 .0 1738 . 5 139 . 78 3932B 5768 .6 5750 .6 1738 .5 34 .80 3934B 5773 .5 5751 . 7 1742 , ,5 23 .45 3935B 5773 .4 5752 .9 1742, .5 5 . 26 3936B 5773, . 1 5753 .5 1742 , .5 192 . 56 3937B 5771 , .0 5752 .5 1742, .7 7 .45 3938B 5769 .0 5750 .9 1742 , .2 73 .06 3939B 5768 . 7 5751 .0 1742 . 2 33 .60 3940B 5768, .5 5752 .3 1742 .2 106 . 18 3941B 5785 ,5 5755 . 1 1739 . O 75 .83 3942B 5781 , . 7 5755 .0 1740, ,9 45 . 1 1 3943B 5781 , .7 5754' .3 1740, ,9 81 . 70 3944B 5780, .0 5754 .8 1738. ,6 7 .06 3945B 5780. .0 5754 . 1 1738. .6 18 .64 3946B 5777 , .5 5754 .0 1739, . 1 20 .62 3947B 5779, 3 5755 .0 1740 .9 97 .73 3948B 5779 . , 3 5755 , 4 1740. ,9 3 . 22 3949B 5773 . 4 5754 , , 1 1742 . 9 61 .47 1S32 5753 . ,0 5745, . 3 1729 , ,8 9 . 34 1633 5753 . ,0 5745, .0 1729. 8 207 . 12 1635 5744 . ,4 5744 .6 1730. .0 13 .86 1636 5744 . .4 5744 . 3 1730. .0 . 16 .04 1637 5744. 4 5743. ,8 1730. 0 38 .98 1638 5744 . 5 5743 . . 4 1730. 0 90 .63 1640 5750 . 0 5745, , 1 1730. ,0 4 .60 1641 5750 . O 5744 . 8 1730. O 1 14 . 28 1642 5748 . .4 5744 , ,0 1730. ,0 22 .06 1643 5747 . 1 5744 , . 8 1730. O 8 . 17 1644 5747 . 1 5744 , .6 1730. ,0 46 .69 1645 5747. 1 5744 2 1730. O . 13 .80 1646 5771 . 0 5743 . .7 1730. 2 38 .94 1647 5769 . 8 5743 . 8 1730. 3 39 .39 1648 5766 . 7 5744 . ,5 1730. 3 57 . 19 1 176 5764. .0 5744 . ,5 1730. 3 75 .91 1 177 5764 . 0 5744 , ,0 1730. 3 17 .65 1 179 5760 . 9 5745 . .0 1730. 4 2 . 44 1 180 5760 . 9 5744 . 7 1730. 4 22 . 69 1181 5760 . 8 5744 . 2 1730. 4 2 . 79 1 182 5757 . 9 5745 . 3 1730. 3 3 .86 1 183 5757 . 8 5745 . 0 1730. 3 28, .00 1 184 5757 . 8 5744 . 7 1730. 3 8 .99 1715 5752 . 4 5739. 0 1716. 1 34 . 17 1716 5752 . 3 5739. 3 1716 . 1 17 .96 1717 5752 . 2 5739 . 5 1716. 1 39, . 52 1718 5752 . 1 5739 . 7 1716. 1 16 , . 30 1719 5749 . 4 5737 . 7 1716. 3 72. ,03 1720 5749 . 2 5738 . 3 1716 . 3 41 . .46 1721 5748 . O 5737 . 2 1716 . 1 41 . , 34 1722 5747 . 9 5737 . 5 1716. 1 7 . 09 1723 5747 . 8 5737 . 7 1716 . 1 1 1 . 03 1724 5744 . 7 5739. 4 1717 . 8 48 .08 1725 5746 . 1 5739. 8 1717. 8 46 .09 1727 5743 . 0 5735 . 6 17 16. 3 125 . 25 1729 5745 . 2 5736 . . 4 1716. 2 12 . 58 1732 5750 . ,5 5748 , , 3 1724 . 2 92 .86 1733 5750 . 3 5748 , .7 1724 . .2 13 .9 1734 5750, .0 5749, .0 1724 . 2 2 .09 1735 5748 . 9 5747 , .5 1724 . 2 171 . 49 1738 5750 . .3 5745 . .5 1722 . 2 56 .03 1739 5748. 8 5745 . .0 1722 . 1 37 .66 1740 5750, , 3 5742, .6 1719. . 1 54 . 56 1741 5748 . 8 5741 , .6 1719. 2 48 . 27 1742 5748, .7 5742, .0 1719. .2 47 .44 1743 5748'. .6 5742 .5 1719. . 2 19 .52 1626 5744 . 8 5740 .5 1719 . 5 188 .66 1627 5744. . 7 5740. a 1719. ,5 9 . 40 1628 5746 . .2 5741 .0 1719 . .5 127 .07 1629 5746 .0 5741 .5 1719 . .5 73 .89 PB ZN CU AU WIDTH (%) (%) (%) ( o / t ) (m 38 .4 0 .615 .2000 0 .0 1 . 10 2 7 . 9 1 . 28 .2750 0 .025 1 .05 7 .31 1 .40 . 1450 0 .014 0 . 9 0 24 . 1 1 .43 .2100 0 .004 0 . 55 15.6 1 . 14 . 2700 0 .0 1 . 3 47 . 2 0 .22 .0568 0 .004 0 . 3 8 2 7 . 7 0 .99 .2500 0 .004 0 . 8 0 14.9 0 .833 . 1490 0 .004 0 . 45 2 . 5 8 0 .934 .0615 0 .006 1 . 42 5 1 . 4 0 .520 . 1280 0 .004 0 . 33 5 . 9 8 0 .602 .0620 0 .005 1 . 33 4 2 . 1 0 .318 . 1345 0 .0 0 . 6 0 17.8 0 . 445 .0000 0 .004 0 . 7 0 35 . 3 0 .99 . 3500 0 .022 0 . 8 0 34 . 4 1 . 4 1 . 1300 0 .O 0 . 5 0 3 6 . 6 1 .09 . 1800 0 .047 0 . 5 0 2 5 . 9 1 .84 . 1300 0 .016 0 . 8 4 4 . 73 1 .05 .0820 0 .01 1 0 . 6 7 10.4. 1. 29 .0790 0 . 0 2 2 0 . 75 13 .9 1.1 08 . 1070 0 . 0 0 . 6 4 3 5 . 9 0 . 96 .2150 0 . 0 0 . 4 0 2 .71 0 . 761 .0210 0 . 0 0 . 4 0 2 5 . 9 1.1 82 . 1950 0 .031 0 . 8 3 2 . 9 0 1. 47 .0366 0 .006 0 . 30 5 4 . 7 0 . 407 . 1362 0 . 0 0 4 0 . 33 5 . 1 5 0 . 433 . 1253 0 .004 0 . 2 2 0 . 9 6 4 0 . ! 908 .3014 0 .004 0 . 4 4 3 .74 1. 23 . 3677 0 .008 0 . 50 15.6 2 . ! 82 .9380 0 . 0 0 . 3 3 5 . 2 3 0 . ' 594 . 1001 0 . 0 0 . 2 2 3 5 . 8 0 .637 . 3293 0 .012 0 . 37 1 .63 1 .45 .2967 0 .006 0 . 50 1 .90 0 . 275 .0563 O .004 0 . 33 19 . 7 1 .02 . 3822 0 .010 0 . 2 0 1 .OO 1 . 90 . 1083 O .O 0 . 56 9 .81 1 .76 . 1997 0 .018 0 . 8 8 8 . 25 1 . 18 .2712 0 .012 1 .05 19.5 1 . 1 1 . 3067 0 .006 0 . 5 7 20. 2 1 .48 . 2202 0 .010 0 . 35 2 . 1 3 1 . 33 . 1797 0 .006 0 . 4 2 3 .48 0 .710 .0845 0 .0 0 . 28 25 . 7 1 .OO . 1701 0 .018 0 . 4 7 1 . 25 0 .958 .0596 0 .0 0 . 40 1 .95 0 . 137 .0279 0 .004 0 . 1 5 9 . 20 1 .47 . 2982 0 .008 0 . 35 2 .47 0 .998 : .0820 0 .004 0 . 35 0 .557 1 : 21 . 2990 0 .0 0 . 25 0 .381 1 . 12 .3150 0 .0 0 . 30 0 . 6 7 5 1 . 12 . 4850 0 .0 0 . 30 0 . 230 0 . 70 . 1525 0 .01 0 . 1 5 1 .01 1 . 18 . 2280 0 .042 0 . 5 0 0 . 8 5 0 . 875 .31 10 0 .014 0 . 50 3 .60 1 .56 . 3690 0 .016 0 . 25 0 . 224 o . 89 .0235 0 .0 0 . 25 0 . 288 0 . 98 . OT80 0 .0 0 . 25 7.11 1 .55 . 1850 0 .013 1 .30 4 .08 1 .80 . 3780 0 .034 1 . 40 3 .31 1 . 98 . 3330 0 . 200 0 . 30 0 . 588 1 .09 . 1770 0 .0 0 . 48 13.6 1 . 16 . 2550 0 .0 0 . 4 5 1 .68 1 .26 . 1960 0 .0 0 .31 0 . 2 16 0 .663 .0160 0 .0 0 . 36 35 . 3 0 .676 .2785 0 .0 0 . 2 0 3 .01 0 . 746 . 2380 0 .004 0 .91 5 .66 0 .690 . 2240 0 .0 0 .81 4 .94 1 .32 . 4900 0 .017 1 . 30 4 . 6 0 0 . 746 . 2460 0 .006 0 . 26 3 . 38 1 .92 .2150 0 .006 0 . 58 0 . 555 0 . 598 . 1385 0 .005 0 . 32 15.2 1 .71 . 3800 0 .081 0 . 5 0 0 . 9 3 0 1 .90 .0640 0 .015 0 . 50 16 .0 1 . 74 .3100 0 .047 0 . 5 0 7 .88 2 . 33 .8300 0 . 162 0 . 5 0 169 WALLROCK SAMP X - A X I S Y - A X I S Z - A X I S AG PB ZN CU AU WIDTH NUM EAST(m) NORTH(m) ELEV(m) ( o / t ) (%) (%) (%) ( o / t ) (m: 1712 5752. .7 5750 .5 1735. ,5 0 . . 26 0 .095 4. .320 .0074 0 . 0 1. 9 1713 5752. .8 5749 .4 1735, .5 0 , , 35 0 . 303 3 . ,67 .0025 0 . o- 1. 0 1714 5753. .0 5748 . 2 1735. .5 0 . 71 0 .451 1 . 23 .0039 0 . 0 1. 0 1630 5773. 6 5749 .0 1736, 8 0 . .36 0 .540 0 . 396 .0045 0 . 0 0 . 9 1631 5752, .8 5745 .8 1730. .4 0 . ,90 0 .505 4. 85 .0092 0 . 0 0 . 43 1 185 5757 8 5744 . 3 1730, .0 0 . . 18 0 . 126 0 . , 193 .0033 0 . .0 . 0 , 46 1736 5748. 8 5747 .9 1724 , ,0 1 06 0 . 135 1 . 76 .0205 0 . 0 0 . 52 1737 5748 , , 7 5748. . 3 1724 , ,0 1 , ,70 0 . 246 2. 48 .0218 0 . ,0 0 . 25 3933 5771 . .3 5751 .0 1739, ,0 0 , ,98 0 .611 0 . . 273 .0054 0, .0 0 . .70 1634 5753. . 1 5744 .6 1729 .8 0, .64 0 .200 0 . .341 .0141 0, .004 0 . ,60 1639 5750 . 1 5744 . 5 1730 .0 1 , . 14 0 . 145 0 .537 .0157 0 .004 0, .26 1649 5766. . 7 5744 .0 1730. . 3 1 , . 16 0 .622 1 . .00 .0256 0, .006 0, , 34 1726 574 1 . , 2 5735 .5 1716 . . 2 0 . 23 0 .050 0 . ,890 .0019 0 .0 0, .65 1728 5742. 8 5735 .9 1716, .3 0 , . 22 0 .095 1 , .01 .0014 0 .0 0 .40 1730 5745. .0 5736 .8 1716 . 2 6. .45 0 .071 0 .663 .0063 0 .0 0 .46 1731 5744 . .9 5737 . 2 1716, . 2 0 .09 0 .049 0 . 777 .0045 0 .0 0 .27 1650 5764 . .0 5744 . 7 1730, .3 1, .07 0 . 749 0, .328 .0137 0 .0 0 . 25 1 178 5760 .9 5745 ; 3 1730. .4 1. .48 0 .569 0 .070 .0093 0 .0 0 . 30 1685 5730. . 1 5741 . 4 1731 , .8 1 . 1 1 0 .305 0, .253 .0000 0 .0 0 .60 1686 5730. . 1 5742 .0 1731 .8 1 .81 0 .642 0 . 103 .0091 0 .0 0 . 75 1663 5728 , 7 5738 . 1 1727 , .5 0 , .90 0 . 176 0 .618 .0084 0, .0 0, .62 1664 5728. .7 5738 . 7 1727, .5 0, . 16 0 . 104 0 .296 .0026 0 .0 0 .62 1667 5750. . 1 5738 . 3 1727 . 1 0 , .67 0 . 131 0 . 795 .0072 0 .0 0 .53 1689 5735. .8 5738 .8 1727 .4 3 .07 1 . 15 0 . 126 .0000 0 .0 0 .40 1671 5756 . .8 5734 .6 1718 , .5 0 , , 54 0 . 160 0, .431 .0086 o .0 1 .0 1672 5757 . .0 5733 .8 1718 .5 0 . ,82 0 . 204 0 .638 .0042 0 .0 0 .80 APPENDIX B A theoretical model for sedimentary sulphide formation on the sea floor i s represented schematically in Figure B-1. In the model iron sulphide production takes place below the oxidized-reduced boundary at a rate controlled by biogenic sulphate reduction and a v a i l a b i l i t y of reactive metals. The redox boundary in Figure B-1 i s within the sediments at a depth below the sediment-water interface equal to the depth of oxygen d i f f u s i o n . In areas of r e s t r i c t e d water c i r c u l a t i o n and high concentrations of organic matter, aerobic metabolism by organisms can deplete oxygen such that the redox boundary becomes coincident with the sediment-water interface or p e r i o d i c a l l y occur above i t (e.g. Black Sea: Berner, 1970). In the l a t t e r case, sulphidized bottom water p r e v a i l . Mathematical models invoking a coincidence in time and space of sulphidized bottom waters and metal-rich exhalations indicate that for most black c l a s t i c f i l l e d sedimentary basins the l i m i t i n g factor for the production of ore grade metal sulphides i s a v a i l a b i l i t y of metals (Rickard, 1973). The system (Fig. B-1) as a whole moves upwards in response to sedimentation, superimposing l a t e r and d i f f e r e n t biogeochemical conditions one atop the other. The v a r i a t i o n in sulphide forms, overgrowths and replacement textures result from p r e c i p i t a t i o n at d i f f e r e n t times during diagenesis. Related forms i d e n t i f i e d within the Slocan sediments include framboids, i n c l u s i o n - r i c h porphyroblasts, concretions and 170 WATER S e d i m e n t - W a t e r M E T A B O L I Z A B L E O R G A N I C C A R B O N M E T A L S S e d i m e n t a t i o n I R a t e = x i n t e r f a c e OXIDIZED ZONE O x i d i z e d - R e d u c e d b o u n d a r y REDUCED ZONE FERMENTATION B o u n d a r y r i s e s j a t r a t e = x ' T h e r m a l D e g r a d a t i o n ++ M E T A L S U L P H I D E P R O D U C T I O N F e S C H 2 0 + 0 2 2CH 2 0 + S O ; H S " + 0 2 2-H + + HCO3-— 2HCO3-+ H S " + H + S 0 4 2 + H + C H 2 0 - 4 F e O - O H 2+ H C 0 3 " + 4 F e + 7 0 H " 5) F e 2 + + HS" -*• F e S + H + (6) ( ? ) m i c r o b i o l o g i c a l a c t i v i t y ( ? ) ® F e S + S° ^ F e S 2 F i g u r e B-1. S c h e m a t i c r e p r e s e n t a t i o n o f the d i s t r i b u t i o n ( v e r t i c a l a r r o w s ) o f c h e m i c a l s p e c i e s w i t h i n the t h r e e ' b l o g e o c h e m l c a l z o n e s ' of C l a y p o o l and K a p l a n , ( 1 9 7 4 ) . H o r i z o n t a l a r r o w s d e s i g n a t e r e a c t a n t s ; numbers , c h e m i c a l r e a c t i o n s w h i c h c o l l e c t i v e l y d e s c r i b e . t h e p r e c i p i t a t i o n o f m e t a l s u l p h i d e s t h r o u g h b a c t e r i a l s u l p h a t e r e d u c t i o n . Model a d a p t e d f r o m B e r n e r (1969) and R l c k a r d ( 1 9 7 3 ) . i d i o b l a s t i c c r y s t a l s . Framboids probably formed within the unconsolidated upper few centimeters of sediments by reactions of metal-rich solutions with biogenic sulphide ions in the presence of native sulphur (Berner, 1969; Sweeney and Kaplan, 1973; Rickard, 1970). A P P E N D I X C SLOCAN REGIONAL ROCK GEOCHEMISTRY SAMPLE NO. PB % ' ZN % AG O/T CO % N I % BA % CD % S 5 0 NB 14-B . 1600 1 . 140 .629 .0030 .0040 .276 .0118 3. 04 NB 1401A 3 .6000. .0040 4 .694 .0051 .0035 .016 .00054 22 . 68 NB 1408 . 0058 .0104 .017 .0030 .0050 .096 .00017 81 NB 1409 . 5600 .9600 1 .576 .0020 .0035 1. 176 .0088 1 . 70 NB 1410 .0035 .0780 . 141 .0055 .0300 . 176 .00192 5. 42 PA 606 .0023 .0105 .082 .0025 .0050 .256 .00019 8. 42 PA 606A-4 .0010 .0073 . 109 .0035 .0090 1 . 272 .00022 8 . 83 PA 606A-6 .0019 . 4400 .092 .0030 .0140 .216 .0059 3 . 48 PA 606A-8 .0045 .0960 . 129 .0065 .0300 .336 .00144 12. 31 PA 606A-11 .0005 .O081 .006 .0010 .0015 .376 .00022 29 PA 606A-14 .0024 .O083 .074 .0080 .0080 . 136 .00031 16. 27 CD 1402C . 172 .0138 . 147 .0065 .0085 . 176 .00049 7, .96 CD 1403C .0251 .0548 .071 .0025 .0065 .096 .00112 2 . 13 CD 1404C .0065 .0090 .044 .0040 .0075 .576 .00044 10 .23 CD 1405C .0052 .0500 .053 .0025 .0080 .422 .00109 1 .58 CD 1406C .0060 .0135 .065 .0040 .0045 .096 .00044 2 . 15 CD 1408C .0052 .0111 .038 .0020 .0030 .096 .00066 . 30 CD 1409C .0088 .345 .088 .0055 .0450 .016 .0056 . 12 CD 14 IOC .0016 .0014 .032 .0005 .0010 . 136 .00007 .26 CC 1501B .0030 .0105 .021 .0030 .0065 .016 .00018 1 .34 CC 1502 .0025 .0135 .006 .0035 .0040 .096 .00029 .67 CC 1504 A .0027 .0115 .026 .0045 .0035 .096 .00022 1 .03 CC 1515 .0030 .0098 .044 .0035 .0080 .016 .00019 1 . 10 CC 1516 . 0020 .01 10 .017 .0040 .0040 .016 .00032 1 .32 ID 1707 .0028 .0190 .012 .0055 .0030 .216 .00018 1 . 13 ID 1708 .0045 .020 .024 .0040 .0030 .005 .00027 .96 ID 1709 .0021 .0110 .012 .0050 .0030 .016 .00013 .71 ID 1709C .0015 .0084 .012 .0035 .0050 .056 .00019 1 .05 PR 1902 .0019 .0085 .015 .0030 .0060 .096 .00035 .96 PR 1904 .0022 .0099 . 106 . 0040 .0155 .196 .00012 -5 .00 RD 2003 .001 1 .0310 .017 .0030 .0065 .056 .00102 1 .03 RD 2004 .0017 .0170 .009 .0035 .0045 .016 .00043 1 .46 RD 2005 .001 1 .01 19 .015 .0030 .0035 .016 .00021 1 . 52 RD 2006 .0017 .0120 .015 .0035 .0050 .005 .00043 1 .35 BO B1003 .0034 .01 10 .021 .0060 .0040 .016 .00030 1 .31 BO B1004 .0014 .0114 .012 .0035 .0050 .056 .00037 .96 BO B1005 .O018 .0255 .017 .0035 .0055 .056 .00062 1 .48 BO B1006 ~ .0026 .0140 .029 .0050 .0040 .005 .00022 1 .85 BO B1007 .0023 .0127 .006 .0050 .0030 .056 .00026 .91 BO B1008 .0020 .0130 .015 .0040 .0025 .096 .00021 .91 BO 2004 .0024 .0105 .017 .0055 .0040 .056 .00026 1 . 24 BO B2009 .0023 .0139 .006 .0045 .0030 .096 .00018 .68 WW W2202A .0016 .0104 .071 .0025 .0050 . 176 .O0O26 2 . 13 WW W2202B .0012 .0019 .062 . 0005 .0010 .016 .00O06 . 12 CU CU8201 .0015 .0068 .003 .0055 .0065 .036 .00015 .35 CU CU8204 .0019 .0126 .012 .0045 .0065 .096 .00026 .06 CU CU8206 .0018 .0099 .006 .0050 .0060 .096 .00019 .07 CU CU8207 .0015 .0035 .006 .0030 .0020 .076 .00014 .79 CU CU8207A .0022 .0040 .006 .0025 .0020 .036 .00010 2 .07 ss J8401S .0091 .2500 .582 .0050 .0400 .096 .0057 .65 SS 08402S .0047 .2900 .965 .0050 .0450 .456 .0064 1 . 17 SS J8403S .0020 1.4500 . 144 .0045 .0950 .296 .0O154 .82 SS U8404S .0020 .0240 .017 .0020 .O025 . 176 .00011 .07 SS J8405S .0O24 .5500 . 188 .0035 .0500 .016 .00035 .29 ss J8406S .0018 .0061 .003 .0030 .0020 .056 .00007 6 .43 ss J8407S .0020 .0164 .006 .O045 .0075 .016 .00022 . 10 SL 8201 .0021 .0045 .009 .0055 .0035 .056 .00017 .05 SL 8202 .0022 .0096 .006 .0050 .0050 . 176 .00018 1 .06 SL 8203A .0027 .0190 .015 .0070 .01 10 .096 .00038 .45 SL 8203B .0020 .0072 .006 .0065 .0021 . 176 .00019 . 17 SL 8203C .0022 .0119 ;009 .0060 .0075 .036 .00022 .25 SL 8204 .0020 .0085 .003 .0050 .0065 .005 .OOO16 .79 SL 8205 .0022 .0084 .012 .0055 .0080 .056 .00019 .95 SL 8206 .0016 .0055 .009 .0050 .0060 .016 .00015 . 3 1 SL 8207 .0018 .0128 .006 .0060 .0085 .016 .00015 .47 SL 8208 .0025 .0062 .006 .0055 .0060 .056 .00030 .34 SL 8209 .0019 .0137 .009 .0055 .0085 .056 .00020 .04 SL 8210 .0018 .O065 .006 .0035 .0045 .036 .00018 . 10 SL 8218 .0016 .0089 .001 .0035 .0055 .016 .00018 .02 173 174 DUPLICATE SAMPLES ROCK GEOCHEMISTRY SAMPLE NO. PB % ZN % AG o / t CO % NI % BA % CD % ' S % PA 606A-4 .0010 .0073 . 109 .0035 .0090 1 .272 .00022 8 .83 PA 606A-14 .0024 .0083 .074 .0080 .0080 . 136 .00031 16 .27 CD 1406C .0060 .0135 .065 .0040 .0045 .096 .00044 2 . 15 CD 1408C .0052 .0111 .038 .0020 .0030 .096 .00066 .30 CC 1501B .0030 .0105 .021 .0030 .0065 .016 .00018 1 .34 CC 1502 .0025 .0135 .006 .0035 .0040 .096 .00029 .67 ID 1709 .0021 .0110 .012 .0050 .0030 .016 .00013 .71 ID 1709C .0015 .0084 .012 .0035 .0050 .056 .00019 1 .05 80 B1003 .0034 .01 10 .021 .0060 .0040 .016 .00030 1 .31 BO B2004 .0024 .0105 .017 .0055 .0040 .056 .00026 1 .24 BO B1008 .0020 .0130 .015 .0040 .0025 .096 .00021 .91 BO B2009 .0023 .0139 .006 .0045 .0030 .096 .00018 .68 CU CU8207 .0015 .0035 .006 .0030 .0020 .076 .00014 . 79 CU CU8207A . 0022 .0040 .006 .0025 .0020 .036 .00010 2 .07 SS U8401S .0091 .2500 .582 .0050 .0400 .096 .0057 .65 SS J8402S .0047 . 2900 .965 .0050 .0450 .456 .0064 1 . 17 SL 8201 ..0021 .0045 .009 .0055 .0035 .056 .00017 .05 SL 8202 .0022 .0096 .006 .0050 .0050 . 176 .00018 1 .06 SL 8209 .0019 .0137 .009 .0055 .0085 .056 .00020 .04 SL 8218 .0016 .0089 .001 .0035 .0055 .016 .00018 .02 DETECTION LIMITS Pb Zn Ag Co N1 Ba Cd S (ppm) 2 . 0 1.0 0 . 1 1.0 ' 1 . 0 10 .0 0 . 1 0 .01 R e l a t i v e s t a n d a r d a n a l y t i c a l e r r o r s E1ement N S X S/X % Pb (%) 9 0 . 0 0 0 6 0 . 0 0 2 5 24 .0 Zn (%) 9 0 . 0 0 2 3 0 . 0 0 9 8 2 3 . 6 Ag ( o / t ) 9 0 .0011 0 .0221 5 . 0 6 Co (ppm) 9 13.8 43 .0 32 .09 N1 (ppm) 9 13 .3 46 . 1 2 8 . 8 5 Ba (%) 9 0 . 166 0 . 137 121.49 Cd (ppm) 9 0 . 7 7 2 .41 31 .95 S (%) 9 1 .43 2 . 1 9 6 5 . 2 3 S = s q u a r e r o o t o f mean s q u a r e d i f f e r e n c e X = a r i t h m e t i c mean S/X = mean r e l a t i v e e r r o r 175 SLOCAN REGIONAL GEOCHEMISTRY ROCK SAMPLE DESCRIPTIONS SLOCAN GROUP ( f i n e g r a i n e d e l a s t i c s ) L i t h o l o g l c a l U n i t " 1 " SAMPLE NO. LITHOLOGY SULPHIDES (% and f o r m ) ( p y r i t e u n l e s s I n d i c a t e d ) COMMENTS WW W2202A s l a t e 3% a u t h l g e n l c / m e t a m o r p h i c e u h e d r a . f r a m b o l d c o r e s c a r b o n a c e o u s q t z p r e s s u r e shadows WW W2202B s l a t e 0.5% d i s s e m i n a t e d cubes p r e s s u r e shadows L i t h o l o g l c a l U n i t " 2 " SAMPLE NO. LITHOLOGY SULPHIDES (% and f o r m ) ( p y r i t e u n l e s s I n d i c a t e d ) COMMENTS CC 1501B s 1 1 t s t o n e 2% l e n s o l d a i a g g r e g a t e s o r i e n t e d / / t o c l e a v a g e c r e n u l a t i o n c l e a v a g e CC 1502 a r g l 1 1 a c e o u s q u a r t z 1te 1% c r y s t a l a g g r e g a t e s CC 1504A g r e y w a c k e 1% i s o l a t e d s u b h e d r a l a g g r e g a t e s and e u h e d r a s e r l c l t l z e d CC 1515 s h a l e / c a l c a r -eous s 1 1 t s t o n e 2% a n h e d r a l - s u b h e d r a l c r y s t a l a g g r e g a t e s p o r p h y r o b l a s t s CC 1516 g r e y w a c k e 1% d i s s e m i n a t e d e u h e d r a BO B1003 g r a n u l e - p e b b l e c o n g l o m e r a t e 1.5% a n h e d r a l r e p l a c i n g c l a s t s (py and po) s e c o n d a r y b i o t i t e s e n d t i z e d BO B2004 B1003 d u p l i c a t e s a m p l e BO B1004 g r e y w a c k e 0.5% a n h e d r a l b l e b s s lump d e p o s i t g r a 1 n s t o n e BO B1005 a r e n a c e o u s s i a t e 2% d i s s e m i n a t e d l e n s o l d a i masses ( p o , p y , t r a c e c p y ) b i o t i t e / / c renula t1< c l e a v a g e BO B1006 g r e y w a c k e 2.5% a n h e d r a l a g g r e g a t e s / / f o l l a t l o n wel1 1 n d u r a t e d m a t r i x r i c h BO B1007 g r e y w a c k e 1% d i s s e m i n a t e d b l e b s c r y s t a l a g g r e g a t e s c r e n u l a t i o n c l e a v a g e b i o t i t e h o r n f e l s BO B1008 g r e y w a c k e 1.5% e v e n l y d i s s e m i n a t e d l e n s o i d masses b i o t i t e h o r n f e l s BO B2009 B100S d u p l i c a t e s a m p l e 176 L i t h o l o g l c a l U n i t " S l a t e B e l t SAMPLE NO. LITHOLOGY SULPHIDES (% and f o r m ) COMMENTS ( p y r i t e u n l e s s i n d i c a t e d ) PA 606 PA 6 0 6 A - 4 PA 606A-11 PA 6 0 6 A - 1 4 CD 1404C CD 1405C CD 1406C CD 1408C CD 1410C PR 1902 PR 1904 L i t h o l o g l c a l SAMPLE NO. t u f f a c e o u s s l a t e s l a t e s l a t e t u f f a c e o u s s i a t e s l a t e s i 1 t s t o n e r h y t h m l t e 1 a m i n a t e d s 1 1 t s t o n e a r g 1 1 1 i t e & q u a r t z l t e 10% a n h e d r a l c r y s t a l a g g r e -g a t e s 1n b e d d i n g / / l e n s e s as f o r Pa 606 not v i s i b l e 20% b e d d i n g / / bands s u b -h e d r a l , e q u a g r a n u l a r p y . 15% r e c r y s t a l 1 1 z e d 0 . 4 cm c r y s t a l a g g r e g a t e s 2% d i s s e m i n a t e d b l e b s 1.5% d i s s e m i n a t e d b l e b s ( p y . and p o . ) 0.5% e u h e d r a p y . as f o r CD 1408C no v i s i b l e s u l p h i d e s s l a t e 1.5% d i s s e m i n a t e d , f r a c t u r e & c l e a v a g e f i l l i n g s & r i m fireplaces s lump fragmenmts s l a t e U n i t " 3 " LITHOLOGY 10% d i s s e m i n a t e d b e d d i n g / / bands & l e n s e s , r e c r y s t a l 1 -i z e d a l o n g t e n s i o n g a s h e s g r a d e d b e d d i n g s c h l s t o s l t y / / b e d d i n g c a r b o n a c e o u s c a l c a r e o u s c o n v o l u t e d b e d d i n g r e c r y s t a l 1 I z e d p y n t e s lump d e p o s i t c a l c a r e o u s c r e n u l a t i o n c l e a v a g e c h l o r 1 t e + c a r b o n a t e c a r b o n a c e o u s c a 1 c a r e o u s s p o t t e d s h a l e 1 am1na11ons(<0.5mm) c a r b o n a c e o u s c a l c a r e o u s c a r b o n a c e o u s s h e a r e d c a r b o n a c e o u s c h l o r i t e p o r p h o b l a s t s SULPHIDES (% and f o r m ) ( p y r i t e u n l e s s i n d i c a t e d ) COMMENTS NB 1408 ID 1707 ID 1708 ID 1709 ID 1709C RD 2003 q u a r t z l t 1 c -a r g i 1 1 1 t e q u a r t z i t l c -a r g l 1 1 1 t e g r e y w a c k e c o a r s e g r e y -wacke (1mm) q u a r t z l t l c -a r g 1 1 1 1 t e s 1 1 t s t o n e (1 ami n . 2mm) 0.5% s u b - e u h e d r a l c r y s t a l a g g r e g a t e s , weak f a b r i c 1.5% b e d d i n g / / d i s s e m i n a t -i o n s , l a y e r s & bands (po) 1.5% d i s s e m i n a t e d b l e b s o f c r y s t a l a g g r e g a t e s (po) 1.0% d i s s e m i n a t e d (po) no v i s i b l e 1.5% d i s s e m i n a t e d b l e b s & f o l i a t i o n / / l e n s o l d s ( p y , p o , t r a c e sph & c p y ) f l a s e r b e d d i n g f a u l t s & s l u m p i n g g r a d e d l a m m a t i o n s ( 1-2mm wel1 - I n d u r a t e d c a r b o n a c e o u s & c a l c a r e o u s b i o t i t e h o r n f e l s c o n v o l u t e d b e d d i n g c h l o r 1 te+carb s p o t t e d h o r n f e l s mass 1 v e - b l o c k y 1 7 7 RD 2004 as f o r RD 2003 e x c e p t l a m i n a t i o n s h o r i z o n t a l no t s l g m o d a l RD 2005 s i l t s t o n e 1.5% r e c r y s t a l l i z e d as f o r RD 2003 RD 200G s i l t s t o n e as above s p o t t e d h o r n f e l s do 1 om 1 te. rhombs ROSSLAND GROUP ( v o l c a n l c s and e l a s t i c s , u n d i v i d e d ) SAMPLE NO. LITHOLOGY SULPHIDES (% and f o r m ) COMMENTS ( p y r i t e u n l e s s I n d i c a t e d ) CU CU8201 CU CU8204 CU CU8206 CU CU8207 CU CU8207A SS J8404S SS J8406S SS U8407S SL 8201 SL 8202 SL 8203A SL 8203B SL 8203C SL 8204 SL 8205 SL 8206 v o l c a n i c f l o w 0.5% d i s s e m i n a t e d b l e b s b r e c c i a p o r p h y r y c o n g l . / w a c k e - no v i s i b l e s t o n e c o n g l o m e r a t e / t r a c e r i m m i n g c l a s t s a g g l o m e r a t e a s h t u f f 1% d i s s e m i n a t e d b l e b s CU8207 d u p l i c a t e sample f l o w b r e c c i a no v i s i b l e a u g i t e p o r p h y r y f l o w b r e c c i a p o r p h y r i t i c s h a r p s t o n e c o n g l o m e r a t e a u g i t e f l o w b r e c c i a g r e y w a c k e g r e y w a c k e 5% r i m m i n g b r e c c i a f r a g -ments & w i t h i n m a t r i x no v i s i b l e no v i s i b l e 0 .5% d i s s e m i n a t e d b l e b s 0.5% b l e b s a u g i t e p o r p h y r y no v i s i b l e , f 1 ow s h a r p s t o n e no v i s i b l e c o n g l o m e r a t e v o l e , s a n d s t o n e 1% d i s s e m i n a t e d cubes & c r y s t a l a g g r e g a t e s a s h t u f f s h a r p s t o n e c o n g l o m e r a t e 0.5% c r y s t a l a g g r e g a t e s 0.5% d i s s e m i n a t e d c u b e s c l a s t s d e f . f o l i a t i o n s e r i c i t e & c a r b o n a t e f l a t t e n e d / / g r a d e d b e d d i ng c a l c a r e o u s m a t r i x m a t r i x s u p p o r t e d weak b e d d i n g / / f o l i a . s c h f s t o s i t y / / f o l i a , s e r i c i t e + c a r b o n a t e c h l o r i t e & s e r i c i t e p r e s s u r e s o l u t i o n f l a t t e n e d p e b b l e s = f o l i c a l c a r e o u s m a t r i x e p i d o t e , c a l c i t e & q t z f i l l f r a c t u r e s muscov1te=weak s c h i s t , c h l o r i t e g r a d e d b e d d i n g c h l o r i t e & c a r b o n a t e . m o d e r a t e l y s o r t e d f l a t t e n i n g = f o l 1 . g r a d e d b e d d i n g weak f o l i a t i o n muscov1te=weak s c h i s t , s e r 1 c 1 1 i z e d 75% p o r p h . v o l e . 20% s h a l e , 5 % l m s t . c l a s t s u p p o r t e d 178 SL 8207 SL 8208 SL 8209 SL 8218 SL 8210 EPIGENETIC SAMPLE NO. v o l e , s a n d s t o n e 0.5% d i s s e m i n a t e d c r y s t a l a g g r e g a t e s v o l e , s a n d s t o n e <0.5% d i s s e m i n a t e d cubes p e b b l e c o n g l . no v i s i b l e SL 8209 d u p l i c a t e sample a s h t u f f no v i s i b l e MINERALIZATION ( u n d i v i d e d ) LITHOLOGY SULPHIDES (% and f o r m ) ( p y r i t e u n l e s s i n d i c a t e d ) c h l o r i t e + c a r b o n a t e g r a d e d b e d d i n g wel1 s o r t e d 75% v o l e . 15% l m s t . 10% q t z + s h a l e c l a s t s c h l o r 1 te+carbonate COMMENTS NB 14-B NB 1401A NB 1409 NB 1410 PA 6 0 6 A - 6 PA 6 0 6 A - 8 CD 1402C CD 1403C CD 1409C SS J8401S c a l c a r e o u s - 1.5% e u h e d r a l p y . + I n t e r -s i l t y q u a r t z l t e s t l t l a l 1% s p h . & t r . g n . as f o r NB 14-B 35% s u b h e d r a l p y . - c r y s t a l a g g r e g . , 1% g n . i n c l u s i o n s l a t e s l a t e s l a t e s l a t e s l a t e s l a t e 0.5% p y . c u b e s , 1.5% s p h . + g n . as b e d d i n g / / l e n s e s t r . gn.+ A g - s u l p h o s a l t 1n x - c u t t i n g f r a c t u r e s 4% f i n e l y d i s s e m i n a t e d p y . s t r a t a b o u n d , 1% c r y s t a l a g g r e g . f r a c t u r e c o n t r o l c a r b o n a t e f l o o d e d r e p l a c e m e n t t e x t u r e s r e p l a c e m e n t r e t a i n s x - b e d d l n g t e x t u r e b e d d i n g / / p r e s s u r e s o l u t i o n weak c r e n u l a t i o n c l e a v a g e c a r b o n a c e o u s 5% p y . lenses(1mm w i d e ) / / p r e s s u r e s o l b e d d i n g , r e c r y s t z d . where t e n s i o n gashes c u t l e n s . 15% p y . b e d d i n g / / bands & l e n s e s ( 2 m m ) , t r . c p y . s p h . and p o . , f r a m b o i d s i n c l a y s i z e l a m i n a t i o n s . 5% s u b h e d r a l cubes(2mm) & l a r g e r c r y s t a l a g g r e g . t r . p o . & c p y . 4% p y . & p o . b l e b s / / c r e n u l a t i o n c l e a v a g e , t r . i n c l u s i o n s c p y . s p h . p o . c a r b o n a c e o u s s o f t s e d . d e f o r m -a t i o n & f a u l t i n g c a r b o n a c e o u s c a l c a r e o u s s p o t t e d s l a t e t r a c e a n h e d r a l b l e b s p y . t u f f a c e o u s 1% p y . 0.5% s p h . 0.5% cpy d e b r i s f l o w a l l as d i s s e m i n a t e d b l e b s r i m & r e p l a c . f r a g m e n t s c a r b o n a c e o u s c r e n u l a t 1 on c l e a v a g e c a l c a r e o u s c l o t s c a r b o n a c e o u s h y d r o t h e r m a l l y b l e a c h e d & b r e c d a t e d ( 7) SS J8402S SS J8401S d u p l i c a t e sample SS J8403S a s h t u f f 0.5% p y . 1% s p h . t r . c p y . b l e a c h e d a l l as b l e b s d e f i n i n g weak b e d d i n g / / f o l i a t i o n SS U8405S a s h t u f f 1% s p h . t r . c p y . as b l e b s weak p r i m a r y f a b r i c & c r y s t a l a g g r e g a t e s b l e a c h e d 

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