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Geochemistry of magnetite and the genesis of magnetite-apatite lodes in the iron mask batholith, British… Cann, Robert Michael 1979

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GEOCHEMISTRY OF MAGNETITE AND THE GENESIS OF MAGNETITE-APATITE LODES IN THE IRON MASK BATHOLITH, BRITISH COLUMBIA by ROBERT MICHAEL CANN B . S c , U n i v e r s i t y o f B r i t i s h C o lumbia, 1976 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department o f G e o l o g i c a l S c i e n c e s ) We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA May, 19 79 © Robert M i c h a e l Cann , 1979 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e Head o f my D e p a r t m e n t o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 W e s b r o o k P l a c e V a n c o u v e r , C a n a d a V6T 1W5 D a t e D E - 6 B P 7 5 - 5 1 I E i i ABSTRACT M a g n e t i t e - a p a t i t e l o d e s , i n the Upper T r i a s s i c I r o n Mask b a t h o l i t h , s o u t h - c e n t r a l B r i t i s h C o l u m b i a , a r e t a b u l a r b o d i e s up to 200 m l o n g and 6 m w i d e w h i c h c o n s i s t o f 50 t o 90 p e r c e n t m a g n e t i t e , 10 to 40 p e r c e n t a p a t i t e and v a r i a b l e amounts o f a m p h i b o l e . Lodes o c c u r i n c l o s e s p a t i a l a s s o c i a t i o n w i t h a l k a l i n e " p o r p h y r y - t y p e " c o p p e r m i n e r a l i z a t i o n , d i s s e m - u v i n a t e d - m a g n e t i t e r i c h d i o r i t e and l a t e s y e n i t i c u n i t s . . To a i d i n d e t e r -m i n i n g t h e g e n e s i s o f t h e s e l o d e s 84 samples o f l o d e m a g n e t i t e and d i s s e m -i n a t e d m a g n e t i t e from d i o r i t i c , s y e n i t i c and p i c r i t i c u n i t s o f t h e b a t h o l i t h were a n a l y z e d by a t o m i c 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 f o r : chromium, c o b a l t , c o pper, l e a d , magnesium, manganese, n i c k e l , t i t a n i u m , vanadium and z i n c , f o u r t e e n samples were a l s o a n a l y z e d f o r major and minor o x i d e s by e l e c t r o n m i c r o p r o b e . M i n o r element d a t a i n d i c a t e s a m a g m a t i c - i n j e c t i o n o r i g i n f o r t h e l o d e s ; m a g n e t i t e b e i n g c o n c e n t r a t e d by i m m i s c i b i l i t y between m a g n e t i t e -a p a t i t e and an a l k a l i c magma. W i t h t h e e x c e p t i o n o f copper and l e a d , minor element v a r i a t i o n s i n m a g n e t i t e due to s a m p l i n g e r r o r and a n a l y t i c a l v a r i a t i o n s a r e i n s i g n i f i c a n t r e l a t i v e to between and w i t h i n r o c k u n i t v a r i a t i o n s , as r e v e a l e d by a n a l y s i s o f v a r i a n c e . D i s s e m i n a t e d m a g n e t i t e f r o m p i c r i t e has h i g h and d i s t i n c t i v e c o n t e n t s o f chromium, magnesium, n i c k e l and z i n c r e l a t i v e t o d i s s e m i n a t e d m a g n e t i t e i n s y e n i t e and d i o r i t e . M i n o r element c o n c e n t r a t i o n s i n d i s s e m i n a t e d m a g n e t i t e from s y e n i t e and d i o r i t e a r e v e r y s i m i l a r s t a t i s t i c a l l y . Lode magnetite,^compared to d i s s e m i n a t e d m a g n e t i t e f r o m d i o r i t e and s y e n i t e , i s m a r k e d l y l o w e r i n chromium and l e s s so i n t i t a n i u m and vanadium, however o t h e r elements o c c u r i n s t a t i s t i c a l l y s i m i l a r c o n c e n t r a t i o n s . . M i n o r element c o n c e n t r a t i o n s i n m a g n e t i t e from I r o n Mask l o d e s a r e s t a t i s t i c a l l y i i i t h e same as t h o s e i n m a g n e t i t e from magmatic i r o n d e p o s i t s i n K i r u n a , Sweden a n d ' M i s s o u r i , U.S.A. M a g n e t i t e from h y d r o t h e r m a l v e i n and metaso m a t i c d e p o s i t s has l o w e r chromium and n i c k e l c o n t e n t s t h a n I r o n Mask l o d e m a g n e t i t e . G e o c h e m i c a l e v i d e n c e p r e s e n t e d h e r e s u g g e s t s t h a t I r o n Mask l o d e s a r e : 1) g e n e t i c a l l y r e l a t e d t o t h e C h e r r y Creek s y e n i t e and Pothook d i o r i t e u n i t s o f t h e I r o n Mask b a t h o l i t h . , and 2) m a g m a t i c a l l y emplaced b a s e d on an a l o g y t o K i r u n a and M i s s o u r i ores'. E x p e r i m e n t a l d o c u m e n t a t i o n o f i m m i s c i b i l i t y between a m a g n e t i t e - a p a t i t e m e l t and a s i l i c a t e magma a l l o w s a model t o be d e v e l o p e d t h a t d e s c r i b e s t h e g e n e s i s o f t h e I r o n Mask b a t h o l i t h . and a s s o c i a t e d m a g n e t i t e - a p a t i t e l o d e s . C r y s t a l s e t t l i n g o f p l a g i o c l a s e and pyroxene from t h e I r o n Mask magma fromed t h e ea r l y . P o thook d i o r i t e and e n r i c h e d t h e r e s i d u a l magma i n i r o n and a l k a l i i s . The magma a l s o d i f f e r e n t i a t e d toward t h e e x p e r i m e n t a l l y determ-i n e d m a g n e t i t e - a p a t i t e e u t e c t i c c o m p o s i t i o n - ( i . e . 20 t o 35 w e i g h t p e r c e n t a p a t i t e i n t o t a l m a g n e t i t e p l u s a p a t i t e ) . When t h e e u t e c t i c was r e a c h e d a f t e r c r y s t a l l i z a t i o n o f Pothgok d i o r i t e , , ( j u s t b e f o r e t h e C h e r r y Creek s y e n i t e s t a r t e d to c r y s t a l l i z e ) m a g n e t i t e and a p a t i t e s e p a r a t e d t o g e t h e r f r o m t h e s i l i c a t e magma as an i m m i s c i b l e m e l t , and s e t t l e d to t h e ba s e o f t h e magma chamber. The m a g n e t i t e - a p a t i t e m e l t was i n j e c t e d i n t o f r a c t u r e s t o fo r m l o d e s a f t e r t he s u r r o u n d i n g C h e r r y Creek magma had l a r g e l y c r y s t a l l i z e d . E x p l o s i v e emplacement o f C h e r r y C r e e k b r e c c i a s and a s s o c i a t e d c opper m i n e r a l -i z a t i o n r e s u l t e d f r o m a~vapor b u b b l e formed i n t h e . f i n a l s t a g e s of. C h e r r y Greek . s y e n i t e c r y s t a l l i z a t i o n . The model p r e s e n t e d shows t h a t m a g n e t i t e - a p a t i t e l o d e s i n t h e I r o n Mask b a t h o l i t h a r e m a g m a t i c - i n j e c t i o n i n o r i g i n . T h e i r g e n e s i s , as w e l l as a s s o c i a t e d p o r p h y r y - t y p e copper m i n e r a l i z a t i o n , i s an i n t e g r a l p a r t o f a d i f f e r e n t i a t i n g a l k a l i c i n t r u s i o n . i v ' TABLE OF CONTENTS Page ABSTRACT i i TABLE OF CONTENTS i v LIST OF FIGURES v i i i L I S T OF TABLES x L I S T OF PLATES x i i ACKNOWLEDGEMENTS x i v CHAPTER 1: INTRODUCTION 1 1.1 G e n e r a l S t a t e m e n t 1 1.2 L o c a t i o n and A c c e s s 1 1.3 H i s t o r y o f D e p o s i t s and P r e v i o u s Work 3 1.4 P u r p o s e and Scope 4 CHAPTER 2: GEOLOGICAL SETTING 6 2.1 I n t r o d u c t i o n 6 2.2 R e g i o n a l Geology 6 2.3 I r o n Mask B a t h o l i t h 8 2.3.1 P i c r i t e 9 2.3.2 I r o n Mask H y b r i d U n i t 10 2.3.3 Pothook U n i t 10 2.3.4 S u g a r l o a f U n i t 11 2.3.5 C h e r r y Creek U n i t 11 2.3.6 S t r u c t u r e 12 2.4 Copper D e p o s i t s A s s o c i a t e d w i t h t h e B a t h o l i t h 13 2.4.1 A f t o n D e p o s i t 13 2.4.2 O t h e r Copper D e p o s i t s 14 2.5 M a g n e t i t e D e p o s i t s A s s o c i a t e d w i t h t h e ''> B a t h o l i t h 15 V Page 2.5.1 Form and D i s t r i b u t i o n 15 2.5.2 M i n e r a l o g y and T e x t u r e s 20 CHAPTER 3: MINOR ELEMENTS IN MAGNETITE 29 3.1 I n t r o d u c t i o n 29 3.2 M a g n e t i t e C r y s t a l C h e m i s t r y 30 3.3 G e n e r a l P r i n c i p l e s G o v e r n i n g M i n o r Element S u b s t i t u t i o n 30 3.4 M i n o r Element S u b s t i t u t i o n i n M a g n e t i t e 34 3.4.1 B e h a v i o u r o f M i n o r Elements i n M a g n e t i t e 37 3.4.2 A p p l i c a t i o n o f Element R a t i o s i n M a g n e t i t e 40 CHAPTER 4: SAMPLING AND ANALYTICAL PROCEDURES 43 4.1 I n t r o d u c t i o n 43 4.2 S a m p l i n g Methods and Sample P r e p a r a t i o n 45 4.3 A n a l y t i c a l P r o c e d u r e s 48 4.3.1 Atomic A b s o r p t i o n 48 4.3.2 E l e c t r o n M i c r o p r o b e 49 4.4 A n a l y t i c a l R e s u l t s 50 4.4.1 D a t a T a b u l a t i o n 50 4.4.2 A c c u r a c y and P r e c i s i o n o f A n a l y s e s 50 4.5 A p p l i c a b i l i t y o f R e s u l t s 52 CHAPTER 5: MINOR AND MAJOR ELEMENTS IN MAGNETITE FROM IRON MASK BATHOLITH 54 5.1 I n t r o d u c t i o n 54 5.2 C o m p o s i t i o n o f M a g n e t i t e Samples from I r o n Mask B a t h o l i t h 55 5.3 C o m p o s i t i o n o f A p a t i t e i n M a g n e t i t e Lodes 60 5.4 M i n o r Element C h a r a c t e r i s t i c s o f M a g n e t i t e f r o m 62 v i Page I r o n Mask B a t h o l i t h 62 5.4.1 D i s s e m i n a t e d M a g n e t i t e 63 5.4.2 M a s s i v e M a g n e t i t e 66 5.5 A n a l y s i s o f M i n o r Element D i s t r i b u t i o n s 71 5.5.1 Comparison o f Means and V a r i a n c e s 71 5.5.2 I n t e r - e l e m e n t C o r r e l a t i o n and R e g r e s s i o n A n a l y s i s 79 5.5.3 Comparison o f M i n o r Element R a t i o s 82 5.5.4 C o n c e n t r a t i o n and A c c u m u l a t i o n i ; ' :i C o e f f i c i e n t s o f M i n o r Elements i n M a g n e t i t e 88 5.6 Comparison o f M i n o r Elements i n M a g n e t i t e Lodes i n I r o n Mask B a t h o l i t h w i t h M i n o r Elements i n M a g n e t i t e D e p o s i t s from o t h e r A r e a s 91 CHAPTER 6: DISCUSSION, SUMMARY AND CONCLUSIONS 99 6.1 I n t r o d u c t i o n 99 6.2 G e n e s i s and O r i g i n o f M a g n e t i t e Lodes 99 6.3 I m m i s c i b l e M e l t Model 103 6.3.1 E x p e r i m e n t a l E v i d e n c e 103 6.3.2 A p p l i c a t i o n o f I m m i s c i b l e M e l t Model t o I r o n Mask B a t h o l i t h 105 6.3.3 D i s c u s s i o n 111 6.4 Summary and C o n c l u s i o n s 114 6.5 S u g g e s t i o n s f o r F u t u r e R e s e a r c h 117 BIBLIOGRAPHY 119 APPENDIX A: SAMPLE SUITE DESCRIPTION 126 APPENDIX B: SELECTED SAMPLE DESCRIPTIONS 130 B . l P o l i s h e d S e c t i o n D e s c r i p t i o n s 131 B.2 T h i n S e c t i o n D e s c r i p t i o n s 135 v i i Page B. 3 Modal A n a l y s e s 145 APPENDIX C: SAMPLING METHODS, ANALYTICAL METHODS, AND DATA TABULATION 150 C. l Sa m p l i n g Methods 151 C.2 A n a l y t i c a l P r o c e d u r e s 154 C.3 A n a l y t i c a l R e s u l t s 159 C.4 A c c u r a c y and P r e c i s i o n o f A n a l y s e s 169 C.5 A n a l y s i s o f V a r i a n c e 186 v i i i L I S T OF FIGURES FIGURE Page 1.1 L o c a t i o n Map 2 2.1 R e g i o n a l Geology 7 So Cjri/ 2.2 Geology, o f t h e N o r t h w e s t H a l f - o f I r o n Mask B a t h o l i t h i n ^ pocke-fe-£/° f Orli. 2.3A Geology o f Magnet Showing-South and C e n t r a l P i t s i n nockat---£f ( A 2.3B Geology o f Magnet Showing-North P i t i n po«efcetr 2.4 P l a n o f G l e n I r o n M i n e 16 3.1 M a g n e t i t e U n i t C e l l S t r u c t u r e 31 5.1 C o m p o s i t i o n o f M a g n e t i t e from I r o n Mask B a t h o l i t h i n Terms o f M a j o r O x i d e s 58 5.2 C o m p o s i t i o n o f M a g n e t i t e from I r o n Mask B a t h o l i t h I n terms o f M a j o r End Components 59 5.3 C o m p o s i t i o n a l Trend o f M a g n e t i t e from I r o n Mask B a t h o l i t h 61 5.4 V a r i a t i o n i n C o b a l t , N i c k e l and Z i n c Abundance A c r o s s Magnet Lode 69 5.5 V a r i a t i o n i n Chromium, Magnesium, T i t a n i u m and Vanadium Abundance A c r o s s Magnet Lode 70 5.6 Mean M i n o r Element C o n t e n t s o f M a g n e t i t e f r o m I r o n Mask B a t h o l i t h 78 5.7 Comparison o f M i n o r Elements i n I r o n Mask Lodes to K i r u n a and M i s s o u r i D e p o s i t s 96 5.8 Comparison o f M i n o r Elements i n I r o n Mask Lodes to M a g n e t i t e i n M e t a s o m a t i c and H y d r o t h e r m a l --V e i n D e p o s i t s 97 6.1 S c h e m a t i c M a g n e t i t e - A p a t i t e - D i o r i t e Phase U ::; R e l a t i o n s h i p s 104 6 . 2 S i m p l i f i e d Geology o f No r t h w e s t End o f I r o n Mask B a t h o l i t h 107 i x FIGURE Page 6.3 • Model f o r G e n e s i s o f M a g n e t i t e - A p a t i t e Lodes 109 C.1 S a m p l i n g Scheme 151 C.2 P r e c i s i o n (20%) Graphs 174 X L I S T OF TABLES TABLE Page 3.1 P r o p e r t i e s o f Ions Which E n t e r M a g n e t i t e S t r u c t u r e 35 3.2 M i n o r Element Abundance i n M a g n e t i t e f r o m V a r i o u s I n t r u s i v e Rocks 36 4.1 D i s t r i b u t i o n o f M a g n e t i t e Samples by Form and H o s t 45 4.2 E s t i m a t e s o f Sample C o n t a m i n a t i o n 47 5.1 E l e c t r o n M i c r o p r o b e A n a l y s e s o f M a g n e t i t e and C h r o m i t e from I r o n Mask B a t h o l i t h 56 5.2 C o m p o s i t i o n o f A p a t i t e i n I r o n Mask Lodes 62 5.3 Summary o f M i n o r Element Abundance i n D i s s e m i n a t e d M a g n e t i t e 64 5.4 Summary o f M i n o r Element Abundance i n M a s s i v e M a g n e t i t e 67 5.5 C a l c u l a t e d F and t V a l u e s f o r M i n o r Element Abundances i n V a r i o u s M a g n e t i t e Groups 72 5.6 Summary o f R e s u l t s o f F and t T e s t s P e r f o r m e d i n T a b l e 5.5 74 5.7 C o r r e l a t i o n M a t r i c e s f o r M a s s i v e and D i s s e m i n a t e d M a g n e t i t e 80 5.8 Comparison o f M i n o r Element C o r r e l a t i o n C o e f f i c i e n t s i n M a g n e t i t e from V a r i o u s L o c a t i o n s 81 5.9 Summary o f M i n o r Element R a t i o s i n D i s s e m i n a t e d M a g n e t i t e 84 5.10 Summary o f M i n o r Element R a t i o s i n M a s s i v e M a g n e t i t e 85 5.11 C a l c u l a t e d F and t R a t i o s f o r M i n o r Element R a t i o s 86 5.12 Summary o f R e s u l t s o f F and t T e s t s G i v e n i n T a b l e 5.11 87 5.13 N i / C r V a l u e s i n M a g n e t i t e f r o m V a r i o u s O r i g i n s 88 5.14 C o n c e n t r a t i o n and A c c u m u l a t i o n C o e f f i c i e n t s o f M i n o r Elements i n I r o n Mask M a g n e t i t e 89 x i TABLE Page '5.15 M i n o r Element Abundances i n M a g n e t i t e from V a r i o u s I r o n D e p o s i t s 92 5.16 Average M i n o r Element Abundance i n I r o n Mask M a g n e t i t e - A p a t i t e D e p o s i t s 93 5.17 Comparison o f M i n o r Elements i n I r o n Mask Lodes to M i s s o u r i and K i r u n a T a g n e t i t e - A p a t i t e D e p o s i t s 94 5.18 P u b l i s h e d M i n o r Element C o n t e n t s o f M a g n e t i t e from H y d r o t h e r m a l V e i n and M e t a s o m a t i c D e p o s i t s 95 6.1 Summary o f Geoch e m i c a l and T e x t u r a l F e a t u r e s o f I r o n Mask Lodes 101 6.2 P e r c e n t A p a t i t e and M a g n e t i t e i n D i o r i t i c and S y e n i t i c Rocks, I r o n Mask B a t h o l i t h 106 A. 1 Sample D e s c r i p t i o n s and L o c a t i o n s 128 B. l C h e r r y Creek U n i t : P o i n t Count D a t a 146 B.2 Pothook U n i t : P o i n t Count Data 147 B.3 P i c r i t e U n i t : P o i n t Count D a t a 148 B. 4 M i s c e l l a n e o u s Rock Types: P o i n t Count Data 149 C. l Reagents Used i n P r e p a r a t i o n o f Atomic A b s o r p t i o n S t a n d a r d s 156 C.2 Atomic A b s o r p t i o n O p e r a t i n g C o n d i t i o n s 158 C.3 Atomic A b s o r p t i o n A n a l y t i c a l R e s u l t s 160 C.4 E l e c t r o n M i c r o p r o b e A n a l y t i c a l R e s u l t s 162 C.5 Summary o f Atomic A b s o r p t i o n R e p l i c a t e A n a l y s e s 170 C.6 P r o b a b i l i t i e s A s s o c i a t e d w i t h F i g . C.2 184 C.7 At o m i c A b s o r p t i o n A n a l y s e s o f S t a n d a r d I r o n Ores 185 C.8 Nes t e d A n a l y s i s o f V a r i a n c e 188 C.9 P o i n t E s t i m a t e s o f V a r i a n c e 193 x i i L I S T OF PLATES PLATE 2.1 M a g n e t i t e Fragment i n C h e r r y Creek P o r p h y r y 2.2 North: P i t o f Magnet Showing 2.3 South P i t o f Magnet Showing 2.4 C e n t r a l P i t o f Magnet Showing 2.5 G l e n I r o n Mine Workings 2.6 M a g n e t i t e Dykes i n C h e r r y Creek U n i t 2.7 P r i s m a t i c A l t e r e d Amphibole C r y s t a l s I n M a s s i v e M a g n e t i t e 2.8 A p a t i t e i n M a g n e t i t e Lode, Magnet Showing 2.9 A p a t i t e i n M a g n e t i t e Lode, Magnet Showing 2.10 A p a t i t e Growing R a d i a l l y Around M a g n e t i t e Fragment 2.11 T r a i n s o f S p i n e l ( ? ) i n M a s s i v e M a g n e t i t e 2.12 E x s o l v e d I l m e n i t e (?) i n M a g n e t i t e 2.13 C o l l o f o r m T e x t u r e i n M a s s i v e M a g n e t i t e 2.14 M a g n e t i t e V e i n l e t s , Magnet Showing 2.15 M a g n e t i t e B r e c c i a , Magnet Showing 2.16 E p i d o t e Core i n M a g n e t i t e V e i n l e t 2.17 C h a l c o p y r i t e L i n i n g a Vug i n M a s s i v e M a g n e t i t e 4.1 L o c a t i o n o f C h i p Samples IM 22-0 t o 10. 4.2 L o c a t i o n o f C h i p Samples IM 21-0 t o 11 B . l G r a n u l a r T e x t u r e I n M a s s i v e M a g n e t i t e B.2 V e i n l e t o f M a g n e t i t e and S u l p h i d e s B.3 E x s o l v e d C h a l c o p y r i t e i n B o r n i t e B.4 E u h e d r a l M a g n e t i t e and S u l p h i d e s x i i i PLATE Page B.5 I n t e r s t i t i a l M a g n e t i t e i n Pothook D i o r i t e 142 B.6 P o r p h y r i t i c C h e r r y Creek M o n z o n i t e 142 B.7 P i c r i t e T e x t u r e 143 B.8 P o r p h y r i t i c C h e r r y C r e e k M o n z o n i t e 143 B.9 Cumulate T e x t u r e i n Pothook D i o r i t e 144 B.10 P i c r i t e T e x t u r e 144 x i v ACKNOWLEDGEMENTS i I would like::to greatly thank Dr. C o l i n I. Godwin for conceiving this research project and for providing much advice, enthusiastic encouragement and f i n a n c i a l aid during a l l stages of t h i s project. Drs. A. J . S i n c l a i r and E. P. Meagher of the writers thesis committee provided advice and c r i t i c a l l y read parts of the thesis r e s u l t i n g i n i much improvement., Drs. K. Fletcher and W. H. Mathews also c r i t i c a l l y read and improved sections of the t h e s i s . My sincere thanks go to my s i s t e r Susan for typing the f i r s t d r a f t of the thesis and for acting as f i e l d assistant during mapping; to Therese Y'u for typing the f i n a l d r a f t ; and to Sue Campbell for her friendship and advice while w r i t i n g the t h e s i s . Ray L e t t and Ann Waskett-Myers provided considerable assistance with a n a l y t i c a l problems. Asger Bentzen aided i n solving computing problems. Graeme McLaren helped with d r a f t i n g . John Knight, Lee Pigage, and Rob Berman helped with microprobe analyses. I also thank Dr. K. E. Northcote for exam-inin g many rock specimens c o l l e c t e d for t h i s study, and D. McCashin who did the i n i t i a l mapping and sampling c o l l e c t i n g for t h i s p r o j e c t . F i n a n c i a l support was kindly provided by the B r i t i s h Columbia Department of Energy, Mines and Petroleum Resources and by the University of B r i t i s h Columbia. 1 CHAPTER 1 INTRODUCTION 1.1 G e n e r a l Statement A w o r l d wide a s s o c i a t i o n i s known t o e x i s t between t a b u l a r t o .-. •. l e n t i c u l a r b o d i e s o f m a g n e t i t e - a p a t i t e and a l k a l i c r o c k s o c c u r r i n g i n a v o l c a n i c o r s u b - v o l c a n i c e n v i r o n m e n t . M a j o r examples i n c l u d e : (1) P a r k ' s (1972) b r i e f d e s c r i p t i o n s o f t h e o c c u r r e n c e s o f m a g n e t i t e - a p a t i t e b o d i e s i n C h i l e , P e r u , M e x i c o , C a l i f o r n i a , P h i l i p p i n e I s l a n d s and A u s t r a l i a , (2) G e i j e r ' s (1931, 1960) d e s c r i p t i o n s o f t h e famous a p a t i t e i r o n o r e s o f K i r u n a , Sweden, and (3) K i s v a r s a n y i ' s and P r o c t o r ' s (1967) work on i r o n d e p o s i t s i n s o u t h e a s t M i s s o u r i . M a g n e t i t e - a p a t i t e b o d i e s a s s o c i a t e d w i t h a l k a l i c r o c k s i n Canada have been n o t e d i n t h e G r e a t Bear b a t h o l i t h , N o r t h w e s t T e r r i t o r i e s (Badham and M o r t o n , 1976) and i n B r i t i s h C o l u m b i a a t G a l o r e Creek p o r p h y r y copper d e p o s i t ( D a v i s , 1962), I n g e r b e l l e p r o p h y r y copper d e p o s i t ( C . I . Godwin, 1978, p e r s . comm.) and i n the I r o n Mask b a t h o l i t h n e a r Kamloops. The o c c u r r e n c e and o r i g i n o f m a g n e t i t e - a p a t i t e b o d i e s a t t h e l a s t m e n t i o n e d l o c a t i o n forms t h e s u b j e c t o f t h i s s t u d y . 1.2 L o c a t i o n and A c c e s s The I r o n Mask b a t h o l i t h i s l o c a t e d 230 k i l o m e t r e s n o r t h e a s t o f V a n c o u v e r , i n s o u t h - c e n t r a l B r i t i s h C o l u m b i a ( F i g . 1.1) a t l a t i t u d e 50.6 degrees n o r t h and l o n g i t u d e 120.5 d e grees west. Most known m a g n e t i t e o c c u r r e n c e s a r e a t t h e n o r t h w e s t end o f t h e b a t h o l i t h ( F i g . 2.2). E x c e l l e n t a c c e s s t o 3 t h e b a t h o l i t h i s p r o v i d e d by t h e T r a n s Canada Highway and s e c o n d a r y g r a v e l o r d i r t r a n c h i n g and m i n i n g r o a d s . A c c e s s t o t h e Magnet showings i s c u r r e n t l y r e s t r i c t e d because i t l i e s w i t h i n t h e A f t o n Mine p r o p e r t y . 1.3 H i s t o r y o f D e p o s i t s and P r e v i o u s Work The p r e s e n c e o f m a g n e t i t e b o d i e s i n t h e I r o n Mask b a t h o l i t h was f i r s t n o t e d by G.M. Dawson (1877). Between 1889 and 1902 13,600 to n n e s (15,000 t o n s ) o f m a g n e t i t e were s h i p p e d f r o m t h e G l e n I r o n mine a t C h e r r y B l u f f s ( F i g . 2.1) f o r use as a f l u x i n c o p p e r s m e l t e r s a t Tacoma, Wash i n g t o n , U.S.A., and T r a i l , B.C. S e v e r a l hundred t o n s o f m a g n e t i t e were a l s o s h i p p e d , presumably as f l u x , from t h e Moose c l a i m ( F i g . 2.2) p r i o r t o 1926. Between 1952 and 1957, s e v e r a l thousand t o n s o f o r e were s h i p p e d from t h e Magnet showings ( F i g . 2.2) f o r use as f l u x ( M c A n d l e s s , 1972). Young and Uglow (1926) p u b l i s h e d t h e f i r s t d e t a i l e d d e s c r i p t i o n o f t h e m a g n e t i t e o c c u r r e n c e s i n t h e b a t h o l i t h . C o c k f i e l d (1948) and-.Mathews (1941) mentioned t h e m a g n e t i t e b o d i e s b r i e f l y i n t h e i r d e s c r i p t i o n o f t h e g e o l o g y o f t h e I r o n Mask b a t h o l i t h and c o n c l u d e d t h e y were h y d r o t h e r m a l d e p o s i t s d e r i v e d from t h e b a t h o l i t h . Rose (1973) n o t e d t h a t m a g n e t i t e f r o m t h e G l e n I r o n mine a t C h e r r y B l u f f s was t i t a n i f e r o u s and v a n a d i f e r o u s . Most e x p l o r a t i o n on t h e b a t h o l i t h has been d i r e c t e d toward d i s c o v e r y o f p o r p h y r y copper t y p e m i n e r a l i z a t i o n . The most n o t a b l e d i s c o v e r y r e s u l t e d i n t h e o p e n i n g o f t h e A f t o n mine and s m e l t e r d u r i n g 1977. These a r e l o c a t e d i m m e d i a t e l y n o r t h w e s t o f t h e Magnet showings. 4 1.4 P u r p o s e and Scope D e s c r i p t i o n s i n t h e l i t e r a t u r e g e n e r a l l y r e f e r t o t h e magnetite-^ a p a t i t e l o d e s i n t h e I r o n Mask b a t h o l i t h as v e i n d e p o s i t s (Young and Uglow, 1926) o r r e p l a c e m e n t d e p o s i t s ( P r e t o , 1972)'''. No one has documented them as magmatic d e p o s i t s a l t h o u g h t h e i r form and p r o x i m i t y t o m a g n e t i t e - r i c h 2 u n i t s o f t h e b a t h o l i t h s u g g e s t s t h a t t h e y might be magmatic i n j e c t i o n d e p o s i t s (Bateman, 1951). The t h r e e , main o b j e c t i v e s o f t h i s s t u d y , t h e r e f o r e , were t o : (1) d e t e r m i n e t h e g e n e s i s o f t h e m a g n e t i t e l o d e s ( i . e . v e i n , m agmatic); (2) d e t e r m i n e w h i c h i n t r u s i v e u n i t o f t h e b a t h o l i t h t h e y o r i g i n a t e d f rom i f t h e y a r e magmatic; and (3) d e t e r m i n e i f r e l a t i o n s h i p s e x i s t between m a g n e t i t e d e p o s i t s and copper m i n e r a l i z a t i o n . F i e l d work f o r t h i s s t u d y c o n s i s t e d o f p l a n e - t a b l e mapping ( a t a s c a l e o f 1:120) o f m a g n e t i t e l o d e s exposed i n t h r e e . p i t s on t h e Magnet showing; c o l l e c t i o n o f more t h a n 40 samples o f m a g n e t i t e from m a s s i v e l o d e s and from d i s s e m i n a t i o n s i n i n t r u s i v e u n i t s f o r s e p a r a t i o n and a n a l y s i s o f m a g n e t i t e ; and e x a m i n a t i o n o f a l a r g e amount o f c o r e from t h e A f t o n p r o p e r t y f o r e v i d e n c e o f p o s s i b l e r e l a t i o n s h i p s between m a g n e t i t e l o d e s and copper m i n e r a l i z a t i o n . •""The t e r m " v e i n " i s used i n t h i s t h e s i s i n t h e g e n e t i c sense i m p l y i n g t h a t m i n e r a l s haveabeen p r e c i p i t a t e d f r o m a h y d r o t h e r m a l f l u i d i n an open f i s s u r e ( c f . P a r k and M a c D i a r m i d , 1975;-p. 6 4 ) . 2 The t e r m "magmatic" i s used i n t h i s t h e s i s t o i n d i c a t e d t h a t t h e m i n e r a l s were once an i n t e g r a l p a r t o f some magma and i m p l i e s t h e d e p o s i t s were formed by s e g r a t i o n o f t h e m i n e r a l s ( w h i l e m o l t e n o r p a r t l y c r y s t a l l i z e d ) , i n j e c t i o n i n a f r a c t u r e and f i n a l c o o l i n g and c r y s t a l l i z a t i o n ( c f . P a r k and M a c D i a r m i d , 1975; p. 15). 5 Because a magmatic o r i g i n was s u s p e c t e d f o r t h e m a g n e t i t e l o d e s t h e p r i n c i p a l a p p r o a c h used i n t h i s s t u d y was m i n o r element " f i n g e r - p r i n t i n g " o f m a g n e t i t e f r o m l o d e s and from s y e n i t e and d i o r i t e h o s t r o c k s . An i n t e r e s t i n g a p p l i c a t i o n of t h i s a p p r o a c h has been d e m o n s t r a t e d by F r u t o s and Oyarzun (1975) on a m a g n e t i t e f l o w i n C h i l e . They showed t h a t amounts o f vanadium, chromium and t i t a n i u m i n E l Laco m a g n e t i t e matched more c l o s e l y t h o s e i n m a g n e t i t e from f e r r u g i n o u s s c h i s t t h a n t h o s e i n m a g n e t i t e from a n d e s i t e a s s o c i a t e d w i t h t h e d e p o s i t . Thus, t h e y c o n c l u d e d t h e o r i g i n o f m a g n e t i t e i n t h e f l o w was from m o b i l i z e d s e d i m e n t a r y i r o n , r a t h e r t h a n from s e p a r a t i o n o f m a g n e t i t e i n v o l c a n i c r o c k s . F o r t h i s p u r p o s e a p p r o x i -m a t e l y 65 samples o f m a g n e t i t e were a n a l y z e d f o r c o b a l t , chromium, c o p p e r , magnesium, manganese, n i c k e l , l e a d , t i t a n i u m , vanadium and z i n c by a t o m i c a b s o r p t i o n methods. I n a d d i t i o n 14 o f t h e s e samples were a n a l y z e d f o r major and minor e l e m e n t s by e l e c t r o n m i c r o probe t o d e t e r m i n e t h e g r o s s c o m p o s i t i o n o f t h e m a g n e t i t e . F i f t e e n p o l i s h e d s e c t i o n s and t w e n t y - e i g h t t h i n s e c t i o n s were examined t o d e f i n e m i n e r a l o g y , p a r a g e n e s i s , s i g n i f i -c a n t t e x t u r e s , and l i k e l y m i n e r a l c o n t a m i n a n t s i n m a g n e t i t e s e p a r a t e s . " M i n o r " i s used i n g e n e r a l sense t o c o v e r a l l c a t i o n s o t h e r t h a n i r o n , w h i c h may o c c u r i n m a g n e t i t e . 6 CHAPTER 2 GEOLOGICAL SETTING 2.1 I n t r o d u c t i o n I r o n Mask b a t h o l i t h l i e s i n a 1200 k i l o m e t r e s t r i p , known as t h e Q u e s n e l Trough ( R o d d i c k e t a l . , 1967), w h i c h e x t e n d s from b e l ow t h e U n i t e d S t a t e s - B r i t i s h C o l umbia b o r d e r t o n o r t h e r n B r i t i s h C o l umbia w i t h i n t h e In t e r m o n t a n e B e l t ( S u t h e r l a n d Brown e t a l . , 1971). South from Kamloops Lake t h e r o c k s a r e known as t h e N i c o l a Group. P l u t o n i c r o c k s i n t h i s b e l t a r e t y p i c a l l y a l k a l i c i n c o m p o s i t i o n and comagmatic w i t h t h e s u r r o u n d i n g v o l c a n i c r o c k s ( B a r r et_ a l _ . , 1976; P r e t o , 1977). The Qu e s n e l Trough i s r i c h i n copper (Ca m p b e l l and T i p p e r , 1970) and c o n t a i n s most o f B r i t i s h C o l u m b i a ' s p r o d u c i n g p o r p h y r y copper mines i n c l u d i n g t h e H i g h l a n d V a l l e y d e p o s i t s , I n g e r b e l l e , Copper M o u n t a i n , A f t o n , B e l l , G r a n i s l e . Numerous n o n - p r o d u c i n g d e p o s i t s a l s o o c c u r i n t h i s r e g i o n , i n c l u d i n g G a l o r e and S c h a f t C r e e k d e p o s i t s . 2.2 R e g i o n a l G e o l o g y The I r o n Mask b a t h o l i t h has an exposed l e n g t h o f 35 k i l o m e t r e s and a v e r a g e s 5 k i l o m e t r e s i n w i d t h ( F i g . 2.1). I s o m a g n e t i c c o n t o u r s (GSC Maps 5216G, 5217G) i n d i c a t e t h e b a t h o l i t h e x t n e d s n o r t h under T e r t i a r y c o v e r f o r a f u r t h e r 20 k i l o m e t r e s . Trend o f t h e b a t h o l i t h i s n o r t h -w e s t e r l y , a c r o s s t h e n o r t h e r l y t r e n d i n g b e l t o f Upper T r i a s s i c N i c o l a Group r o c k s . J L E G E N D TERTIARY c 3 | M a i n l y K a m l o o p s G r o u p *. v o l c a n i c f l o w s , c o n g l o m e r a t e , s a n d s t o n e , s h a l e . UPPER TRIASSIC ,-gx/J Iron Mask & Cherry Creek plutons. [ | | Nicola Group • andesite, basalt,sediments. S a m p l e l o c a t i o n F i g . 2 . 1 . G e n e r a l r e g i o n a l g e o l o g y a r o u n d t h e I r o n M a s k b a t h o l i t h , B.C ( a f t e r C o c k f i e l d , 1 9 4 8 ; N o r t h c o t e , 1 9 7 7 a ; a n d E w i n g , 1 9 7 9 ) . 8 N i c o l a Group r o c k s , i n t h e v i c i n i t y o f t h e b a t h o l i t h , c o n s i s t o f f l o w s , m a s s i v e and bedded t u f f s , and b r e c c i a s , t h a t range i n c o m p o s i t i o n from b a s a l t t o t r a c h y t e - d a c i t e ( N o r t h c o t e , 1977). Fragments f r o m t h e youngest u n i t o f t h e I r o n Mask b a t h o l i t h have been n o t e d i n t u f f s and t u f f b r e c c i a s o f t h i s g roup, however, t h i s u n i t a l s o i n t r u d e s t h e N i c o l a Group ( N o r t h c o t e , 1977) . These c o n f l i c t i n g r e l a t i o n s h i p s have been i n t e r p r e t e d t o i n d i c a t e a comagmatic and c o e v a l n a t u r e t o t h e v o l c a n i c and i n t r u s i v e r o c k s . Metamorphism o f t h e s e r o c k s a r o u n d t h e b a t h o l i t h i s weak but v a r i a b l e , with e p i d o t i z a t i o n common n e a r t h e b a t h o l i t h . R h y o l i t e , l i m e s t o n e , a r g i l l i t e , and c o n g l o m e r a t e have been n o t e d e l s e w h e r e i n t h e N i c o l a Group by C o c k f i e l d ( 1 9 4 8 ) ; M c M i l l a n ( 1 9 7 8 ) ; and Schau (1970). I r o n Mask b a t h o l i t h i s a d i f f e r e n t i a t e d m u l t i - p l u t o n i n t r u s i v e . Because o f t h e c l o s e a s s o c i a t i o n between t h e b a t h o l i t h and m a g n e t i t e l o d e s , i t i s d e s c r i b e d i n S e c t i o n 2.3. The b a t h o l i t h d i s a p p e a r s t o t h e n o r t h u nder a c o v e r o f E a r l y T e r t i a r y Kamloops Group v o l c a n i c and s e d i m e n t a r y r o c k s . These v e s i c u l a r a n d e s i t i c f l o w s , f l o w b r e c c i a s and v e n t b r e c c i a s were d e p o s i t e d on a p r e - T e r t i a r y e r o s i o n s u r f a c e s i m i l a r t o t h e p r e s e n t s u r f a c e ( N o r t h c o t e , 1977a; Ewing, 1979). 2.3 I r o n Mask B a t h o l i t h I r o n Mask b a t h o l i t h can be d i v i d e d i n t o two major p l u t o n s ( F i g . 2.1): t h e 18 k i l o m e t r e l o n g I r o n Mask p l u t o n and t h e s m a l l e r C h e r r y Creek p l u t o n w h i c h o u t c r o p s on b o t h s i d e s o f Kamloops Lake f u r t h e r t o t h e n o r t h w e s t ( C o c k f i e l d , 1948; C a r r and Reed, 1976). A number o f s u c c e s s i v e l y 9 emplaced d i f f e r e n t i a t e d u n i t s c o m p r i s e t h e I r o n Mask p l u t o n . Only t h e y o u n g e s t o f t h e s e u n i t s has been d e s c r i b e d i n t h e C h e r r y Creek p l u t o n . G e n e r a l l y , o l d e r u n i t s a r e b a s i c i n c o m p o s i t i o n w h i l e younger u n i t s a r e more a l k a l i n e . Mathews (1941) f o u n d a s y s t e m a t i c d e c r e a s e i n m a g n e t i t e and a c o r r e s p o n d i n g i n c r e a s e i n a p a t i t e i n g o i n g f r o m b a s i c t o i n t e r m e d i a t e t o a l k a l i n e r o c k s . S u b d i v i s i o n and d e s c r i p t i o n o f t h e b a t h o l i t h , below, i s based m a i n l y on work done by N o r t h c o t e (1975; 1977a; 1977b). R e f e r e n c e s h o u l d be made t o F i g s . 2.1 and 2.2 and t o A p p e n d i x A . f o r d i s t r i b u t i o n o f t h e u n i t s d e s c r i b e d and l o c a t i o n o f samples c o l l e c t e d f r o m t h e s e u n i t s . 2.3.1 P i c r i t e P i c r i t e i s a b a s a l t i c , s e r p e n t i n i z e d r o c k u s u a l l y o c c u r r i n g n e a r c o p p e r p r o s p e c t s as l e n t i c u l a r b o d i e s o c c u p y i n g f a u l t zones ( C a r r , 1956; C a r r and Reed, 1976). M a g n e t i t e o c c u r s as f i n e a n h e d r a l g r a i n s i n t h e m a t r i x and as r e p l a c e m e n t s o f o l i v i n e . Volume c o n t e n t o f m a g n e t i t e i s g e n e r a l l y h i g h , but v a r i e s f r o m t r a c e amounts t o 15 p e r c e n t ( p o i n t count d a t a : A p p e n d i x B ) . B o d i e s o f p i c r i t e a r e known t o o c c u r some d i s t a n c e from t h e b a t h o l i t h ( e . g . a t W a t c h i n g C r e e k ; C o c k f i e l d , 1948) and p r o b a b l y occupy r e g i o n a l f a u l t s ( C a r r and Reed, i b i d . ) . Seven samples o f t h i s u n i t were c o l l e c t e d f r o m v a r i o u s l o c a l i t i e s a t t h e n o r t h end and c e n t r e o f t h e b a t h o l i t h , and f r o m W a t c h i n g C r e e k " ( F i g . 2.1; A p p e n d i x A) f o r m i n o r element a n a l y s i s o f m a g n e t i t e . 10 2.3.2 I r o n Mask H y b r i d U n i t The I r o n Mask H y b r i d u n i t i s a g m a t i t i c , c o n s i s t i n g o f a n g u l a r and rounded m a f i c f r a g m e n t s i n a d i o r i t i c m a t r i x . Fragments range f r o m d i o r i t e , h o r n b l e n d e , and m a g n e t i t e - r i c h gabbro t o x e n o l i t h s o f r e c r y s t a l l i z e d N i c o l a v o l c a n i c r o c k s . M a t r i x i s m e s o c r a t i c t o l e u c o c r a t i c d i o r i t e . N o r t h c o t e (1975) b e l i e v e s t h e fr a g m e n t s might r e p r e s e n t o l d e r i n t r u s i v e e q u i v a l e n t s o f Lower N i c o l a r o c k s , b r o u g h t up by renewed magmatic a c t i v i t y . E x a m i n a t i o n o f one t h i n s e c t i o n r e p r e s e n t i n g t h i s u n i t showed m a g n e t i t e t o o c c u r as f i n e e u h e d r a l d i s s e m i n a t i o n s i n pyr o x e n e and h o r n b l e n d e , and as g r a i n s i n t e r s t i t i a l t o f e l d s p a r . Volume p e r c e n t m a g n e t i t e i n t h i s t h i n s e c t i o n i s 11 p e r c e n t . M a g n e t i t e and copper m i n e r a l i z a t i o n a r e common i n t h i s u n i t . One sample o f t h i s u n i t was t a k e n a t t h e n o r t h w e s t end o f t h e b a t h o l i t h f o r m i n o r element a n a l y s i s o f m a g n e t i t e . 2.3.3 Pothook U n i t Pothook u n i t o c c u r s as a g r a d a t i o n a l zone between I r o n Mask H y b r i d and C h e r r y Creek u n i t s . The r o c k i s d i o r i t i c , medium t o c o a r s e g r a i n e d , p a r t l y c u m u l a t e i n t e x t u r e and i s m a f i c r i c h . E x a m i n a t i o n o f t h i n s e c t i o n s f r o m t h i s u n i t (Appendix B) shows m a g n e t i t e t o o c c u r as i n t e r -s t i t i a l g r a i n s v a r y i n g i n abundance from 5 t o 11 volume p e r c e n t , and as i r r e g u l a r v e i n l e t s . P o t a s s i u m f e l d s p a r becomes i n c r e a s i n g l y common as p e r v a s i v e a l t e r a t i o n and as v e i n s c l o s e r t o t h e C h e r r y Creek u n i t . M a g n e t i t e l o d e s a t t h e Magnet showing ( F i g . 2.2) o c c u r i n t h i s u n i t as w e l l as a number o f s m a l l copper showings w h i c h o c c u r s p o r a d i c a l l y a t t h e n o r t h w e s t end o f t h e I r o n Mask p l u t o n . N i n e samples o f t h i s u n i t were t a k e n f o r m i n o r element a n a l y s i s o f m a g n e t i t e . 11 2.3.4. S u g a r l o a f U n i t T h i s u n i t was f i r s t d e s c r i b e d by .Preto ( 1 9 6 8 ) . T y p i c a l l y t h e r o c k i s a g r e y g r e e n p o r p h y r i t i c d i o r i t e . C o n s p i c u o u s p h e n o c r y s t s o f h o r n b l e n d e and a l m o s t t o t a l absence o f m a g n e t i t e a r e d i a g n o s t i c f o r t h i s u n i t . H o r n b l e n d e and f e l d s p a r p h e n o c r y s t s t y p i c a l l y show a t r a c h y t i c t e x t u r e . Copper m i n e r a l i z a t i o n accompanying a l b i t i z a t i o n and b r e c c i a t i o n i s common e a s t o f J a c k o L a k e , e i g h t k i l o m e t r e s s o u t h e a s t o f A f t o n ( P i g . 2.2). One sample was t a k e n i n t h i s same a r e a f o r minor element a n a l y s i s o f m a g n e t i t e , however, i n s u f f i c i e n t m a g n e t i t e was r e c o v e r e d f o r a n a l y s i s . 2.3.5 C h e r r y C r e e k U n i t The C h e r r y Creek u n i t a l o n g t h e n o r t h m a r g i n o f t h e I r o n Mask p l u t o n was f i r s t d e s c r i b e d by P r e t o ( 1 9 6 8 ) . A wide v a r i e t y o f r o c k s range i n c o m p o s i t i o n f r o m d i o r i t e t o s y e n i t e . C h a r a c t e r i s t i c a l l y r o c k s i n t h i s u n i t have a s p e c k l e d appearance and have a p i n k c a s t . T e x t u r e i s g e n e r a l l y p o r p h y r i t i c o r m i c r o p o r p h y r i t i c , c o n s i s t i n g o f p l a g i o c l a s e , c l i n o p y r o x e n e and r a r e h o r n b l e n d e p h e n o c r y s t s . M a g n e t i t e o c c u r s as a n h e d r a l i n t e r s t i t i a l g r a i n s , as s u b h e d r a l l a t e c r y s t a l l i z i n g g r a i n s , and as an a l t e r a t i o n p r o d u c t o f m a f i c m i n e r a l s . P o i n t c o u n t i n g (Appendix B) shows t h e m a g n e t i t e c o n t e n t t o range f r o m 2 t o 10 p e r c e n t . I r r e g u l a r b o d i e s o f i n t r u s i v e b r e c c i a a r e common a l o n g t h e n o r t h m a r g i n o f t h e I r o n Mask p l u t o n and on t h e n o r t h s i d e o f Kamloops Lake. N o r t h c o t e (1977a) b e l i e v e s t h e v a r i e t y o f r o c k t y p e s "may be t h e r e s u l t o f t a p p i n g magmav a t d i f f e r e n t s t a g e s o f d i f f e r e n t i a t i o n w i t h emplacement and c r y s t a l l i z a t i o n o c c u r r i n g under v a r i e d c o n d i t i o n s o f p r e s s u r e , t e m p e r a t u r e , 12 and v o l a t i l e c o n t e n t . . . " . Copper and i r o n m i n e r a l i z a t i o n a r e common a l o n g t h e n o r t h w e s t m a r g i n of t h e I r o n Mask p l u t o n i n a s s o c i a t i o n w i t h i n t e n s e p o t a s s i u m f e l d s p a t h i z a t i o n and i n t r u s i v e b r e c c i a s . N i n e samples o f t h i s u n i t were t a k e n a t t h e n o r t h w e s t end o f t h e I r o n Mask p l u t o n and a t t h e C h e r r y Creek p l u t o n f o r m i n o r element a n a l y s i s o f m a g n e t i t e . One o f t h e s e samples (IM 16) t a k e n i m m e d i a t e l y n o r t h o f S u g a r l o a f H i l l ( F i g . 2.2) shows an a n g u l a r fragment o f m a s s i v e m a g n e t i t e o c c u r r i n g i n a medium-grained,, p o r p h y r i t i c m o n z o n i t e ( P l a t e 2.1). 2.3.6 S t r u c t u r e Three major zones o f r e c u r r i n g f r a c t u r e , one t r e n d i n g n o r t h w e s t e r l y a l o n g t h e s o u t h w e s t m a r g i n o f t h e I r o n Mask p l u t o n , one t r e n d i n g e a s t e r l y a l o n g t h e n o r t h m a r g i n and one r u n n i n g n o r t h w e s t e r l y w i t h i n t h e p l u t o n were i d e n t i f i e d by C a r r ( 1 9 5 6 ) . O t h e r n o r t h w e s t e r l y and n o r t h e r l y t r e n d i n g f a u l t s have been i d e n t i f i e d by N o r t h c o t e ( 1 9 7 5 ) . These s t r u c t u r e s commonly f l a n k o l d e r and i n t e r m e d i a t e age u n i t s and a p p a r e n t l y p l a y e d an i m p o r t a n t r o l e i n t h e i r emplacement. E a s t e r l y and n o r t h e a s t e r l y t r e n d i n g f a u l t s l o c a l i z e d emplacement o f some younger C h e r r y Creek p h a s e s , b r e c c i a t i o n , p o t a s s i u m f e l d s p a t h i z a t i o n and m i n e r a l i z a t i o n ( N o r t h c o t e , i b i d . ) Most m a g n e t i t e l o d e s w i t h i n t h e I r o n Mask p l u t o n t r e n d e a s t e r l y , p a r a l l e l i n g t h e n o r t h w e s t e r l y c o n t a c t o f t h e b a t h o l i t h . O ther m a g n e t i t e l o d e s s u c h as t h o s e a t t h e Magnet showings t r e n d n o r t h w e s t e r l y p a r a l l e l i n g p r o m i n e n t n e a r b y l i n e a m e n t s ( F i g . 2.2). T h i s p a r a l l e l i s m between l o d e s and s t r u c t u r e s , s u g g e s t s zones o f s t r u c t u r a l weakness p l a y e d an i m p o r t n a t r o l e i n c o n t r o l l i n g emplacement o f t h e m a g n e t i t e . 13 2.4 Copper D e p o s i t s A s s o c i a t e d w i t h t h e B a t h o l i t h Copper m i n e r a l i z a t i o n i n t h e b a t h o l i t h o c c u r s as v e i n s , s t o c k w o r k s o r f r a c t u r e - c o n t r o l l e d d i s s e m i n a t i o n s . D e p o s i t s g e n e r a l l y c l u s t e r around t h e b a t h o l i t h m a r g i n s and a r e a s s o c i a t e d w i t h e a s t - w e s t f a u l t i n g , i n t e n s e p o t a s s i c a l t e r a t i o n and w i t h C h e r r y Creek i n t r u s i o n b r e c c i a s . Because A f t o n i s t h e o n l y p r o d u c i n g mine a t t h e p r e s e n t t i m e and because t h e main orebody i s o n l y 1.25 k i l o m e t r e s from t h e Magnet showings i t i s d e s c r i b e d i n more d e t a i l below ( S e c t i o n 2.4.1). Two o t h e r f o r m e r c o p p e r p r o d u c e r s , t h e Copper K i n g and I r o n Mask m i n e s , a r e a l s o d e s c r i b e d b r i e f l y i n S e c t i o n 2.4.2. 2.4.1 A f t o n D e p o s i t M i n e r a l i z a t i o n a t A f t o n o c c u r s i n s h a t t e r e d C h e r r y Creek r o c k s c e n t r e d on a C h e r r y Creek I n t r u s i v e b r e c c i a ( C a r r and Reed, 1976). The d e p o s i t d e f i n e d by 0.25 p e r c e n t copper c u t o f f i s c r u d e l y t a b u l a r and t r e n d s 290 d e g r e e s a z i m u t h and d i p s 55 d e grees s o u t h . A 300 metre wide zone o f "abundant'.magnetite c o n t a i n s t h e orebody and e x t e n d s s o u t h - • e a s t t o t h e Magnet showings. Copper o c c u r s t o a d e p t h o f 400 m e t r e s as t h e supergene m i n e r a l s n a t i v e c opper and c h a l c o c i t e . N a t i v e c opper o c c u r s as s c a l e s , f i l m s , d e n d r i t e s and g r a n u l e s , w h i l e c h a l c o c i t e r e p l a c e s b o r n i t e and c h a l c o p y r i t e . M a g n e t i t e has l a r g e l y been a l t e r e d i n t h i s zone t o e a r t h y , r e d h e m a t i t e . 14 Deeper t h a n 400 m e t r e s , i n t h e hypogene zone, b o r n i t e and c h a l c o p y r i t e o c c u r as d i s s e m i n a t i o n s and v e i n s . P y r i t e and m a g n e t i t e dykes a r e r a r e . Hypogene copper grade i s s l i g h t l y h i g h e r t h a n supergene grade. Supergene a l t e r a t i o n has l a r g e l y d e s t r o y e d hypogene a l t e r a t i o n p r o d u c t s . P r e t o (1972) and H o i l e s (1978) r e c o g n i z e d t h r e e a l t e r a t i o n s t a g e s : (1) development o f K - f e l d s p a r , s a u s s u r i t i z a t i o n o f f e l d s p a r , c h l o r i t i z a t i o n o f m a f i c m i n e r a l s , (2) l o c a l s e r i c i t i z a t i o n , and (3) e p i d o t e - m a g n e t i t e -c h l o r i t e a l t e r a t i o n . 2.4.2 O t h e r Copper D e p o s i t s Two o t h e r c opper d e p o s i t s i n t h e b a t h o l i t h , t h e I r o n Mask and Copper K i n g , have p r o d u c e d c o p p e r . I r o n Mask mine ( F i g . 2.2) p r o d u c e d , between 1901 and 1928, 2,356, 352 kg (5,194,871 pounds) o f c o p p e r , 102,900 g (3,630 ounces) o f g o l d , and 1,171,000 g (41,292 ounces) o f s i l v e r . Copper K i n g mine ( F i g . 2.1) p r o d u c e d , between 1906 and 1940, 177,527 kg (391,381 pounds) o f c o p p e r , 33,540 g (1,183 ounces) o f g o l d , and 61,800 g (2,180 ounces) o f s i l v e r ( C o c k f i e l d , 1948). M i n e r a l i z a t i o n a t t h e I r o n Mask mine o c c u r r e d i n v e i n s a l o n g a f r a c t u r e zone between s h e a r e d p i c r i t e and I r o n Mask H y b r i d d i o r i t e . s econd orebody o c c u r r e d i n a s h e a r zone i n d i o r i t e , w h i c h c o n t a i n e d s l i c e s o f w e a k l y m i n e r a l i z e d p i c r i t e . Copper c a r b o n a t e s a r e common i n t h e upper p a r t s o f t h e o r e b o d i e s . 15 The Copper K i n g mine i s l o c a t e d a t t h e s o u t h end o f t h e C h e r r y Creek p l u t o n ( F i g . 2.1). C h a l c o p y r i t e , p y r r h o t i t e , b o r n i t e and m a g n e t i t e o c c u r as d i s s e m i n a t i o n s and v e i n l e t s a l o n g a f r a c t u r e zone i n C h e r r y Creek d i o r i t e . E x a m i n a t i o n o f specimens from t h e mine dump shows m a g n e t i t e , accompanied by c h a l c o p y r i t e and b o r n i t e , f o r m i n g a m a t r i x i n b r e c c i a t e d C h e r r y Creek m o n z o n i t e . B o r n i t e a l s o o c c u r s as d i s s e m i n a t i o n s and v e i n l e t s i n t h e c o u n t r y r o c k . P o l i s h e d s e c t i o n s t u d i e s (Appendix B) show m a g n e t i t e and s u l p h i d e s t o be contemporaneous. 2.5 M a g n e t i t e D e p o s i t s A s s o c i a t e d w i t h t h e B a t h o l i t h 2.5.1 Form and D i s t r i b u t i o n Most m a g n e t i t e l o d e s o c c u r as s t e e p l y d i p p i n g , t a b u l a r b o d i e s w i t h s h a r p l y d e f i n e d w a l l s t h a t v a r y i n w i d t h from l e s s t h a n a c e n t i m e t r e t o t h r e e m e t r e s a t t h e Magnet showing ( F i g s . 2.3a, b; P l a t e s 2.2, 2.3, 2.4) and s i x m e t r e s a t t h e G l e n I r o n mine ( P l a t e 2.5). A l t h o u g h g e n e r a l l y s t e e p l y d i p p i n g , a t t h e Moose showing ( F i g . 2.3) d i p s a r e as low as 40 degrees s o u t h ( P l a t e 2.6). The l o d e s t e n d t o s p l i t a t i r r e g u l a r i n t e r v a l s , end a b r u p t l y , and may t e n d t o f o l l o w a c u r v i n g c o u r s e o v e r some d i s t a n c e . A s i n g l e dyke cannot be f o l l o w e d f o r any g r e a t d i s t a n c e because o f l a c k o f o u t c r o p . At G l e n I r o n mine the':main l o d e was f o l l o w e d f o r 200 m e t r e s ( F i g . 2.4; Young and Uglow, 1926). M a g n e t i t e l o d e s a r e c o n c e n t r a t e d a t t h e n o r t h w e s t end o f t h e b a t h o l i t h as shown on F i g . 2.2. They c u t a l l u n i t s o f t h e b a t h o l i t h e x c e p t f o r 16 ) ) .1 Magnetite veins and inferred extensions Drift covered areas (dotted lines). Numerals designate veins as referred to in text. Magnetite in open cut Underground working Scale of Feet Geto/ogica/ Survey. Canada. 'f ? I i f 31° <0S_^3° F i g . 2.4. P l a n o f G l e n I r o n m i n e w o r k i n g s a n d v i c i n i t y . P l a t e 2.5 w a s t a k e n l o o k i n g w e s t a l o n g v e i n No. 8 ( f r o m Y o u n g a n d U g l o w , 1 9 2 6 ) . 17 PLATE 2 . 1 . A n g u l a r f r a g m e n t o f m a g n e t i t e i n p o r p h y r i t i c C h e r r y C r e e k d i o r i t e . C o i n i s 18 mm i n d i a m e t e r PLATE 2.2. N o r t h P i t o f Magnet s h o w i n g ( F i g . 2.3B) l o o k i n g n o r t h t o w a r d t h e A f t o n s m e l t e r s t a c k . V e r t i c a l p i t f a c e i s t h e c o n t a c t b e t w e e n t h e now m i ned o u t m a i n m a g n e t i t e l o d e and s u r r o u n d i n g d i o r i t e PLATE 2.4. C e n t r a l P i t o f Magnet showing ( F i g . the s t e e p l y d i p p i n g , t a b u l a r n a t u r e m a g n e t i t e body. 2 . 3 A ) . Note of t h e P L A T E 2.6. M a g n e t i t e d y k e s i n C h e r r y C r e e k u n i t , M o o s e s h o w i n g ( F i g . 2 . 2 ) . D y k e s d i p a p p r o x i m a t e l y 4 5 s o u t h . 20 p i c r i t e and S u g a r l o a f u n i t s . A l o n g t h e n o r t h w e s t m a r g i n o f t h e I r o n Mask p l u t o n , and a t t h e G l e n I r o n mine, most l o d e s t r e n d i n an e a s t - w e s t d i r e c t i o n , however, t h o s e l o d e s a t t h e Magnet showing and t h o s e s o u t h e a s t o f t h e Moose showing t r e n d n o r t h w e s t e r l y . 2.5.2 M i n e r a l o g y and T e x t u r e s Because m a g n e t i t e l o d e s a t t h e Magnet showing a r e t h e b e s t exposed, t h e y were s t u d i e d i n more d e t a i l t h a n o t h e r s . U n l e s s o t h e r w i s e s p e c i f i e d t h e f o l l o w i n g o b s e r v a t i o n s on m i n e r a l o g y and t e x t u r e a r e f r o m s t u d y of t h e Magnet l o d e s . L a r g e l o d e s a t t h e Magnet showing ( F i g . 2.3a, b) c o n s i s t p r e d o m i n a n t l y o f a m a t r i x o f m a s s i v e m a g n e t i t e , c o n t a i n i n g w h i t e o r p a l e p i n k e u h e d r a l a p a t i t e c r y s t a l s up t o t h r e e c e n t i m e t r e s l o n g , and p r i s m a t i c a m p h i b o l e c r y s t a l s up t o s i x c e n t i m e t r e s l o n g ( P l a t e 2.7). P a t c h e s of c h l o r i t e have been o b s e r v e d i n m a g n e t i t e r u b b l e a t t h e N o r t h P i t ( F i g . 2.3a). The f o r m of t h e b o d i e s and a r e a s o f a m p h i b o l e c o n c e n t r a t i o n a r e shown i n F i g s . 2.3a and 2.3b. Amphibole and a p a t i t e c r y s t a l s o c c u r w i t h t h e i r l o n g a x i s e l o n g a t e d p e r p e n d i c u l a r t o t h e w a l l s of t h e l o d e s , and i n d i s c r e t e zones p a r a l l e l i n g t h e w a l l s b u t u s u a l l y s e p a r a t e d f r o m them by a zone o f m a s s i v e m a g n e t i t e ( P l a t e s 2.8 and 2.9). Sometimes a number o f zones o f a p a t i t e and a m p h i b o l e o c c u r between t h e w a l l and c e n t r e o f t h e l o d e . Amphibole o r a p a t i t e c r y s t a l s a r e f r e q u e n t l y r a d i a l l y o r i e n t e d around m a g n e t i t e f r a g m e n t s a p p a r e n t l y " f l o a t i n g " i n m a s s i v e m a g n e t i t e ( P l a t e 2.10). Amphibole does n o t o c c u r i n a l l l o d e s : f o r example none has been o b s e r v e d i n n a r r o w dykes a t t h e Magnet showing , i n t h e A f t o n d r i l l core-; o r a t 21 P L A T E 2.8. A p a t i t e z o n e s p a r a l l e l i n g c o n t a c t s o f a s m a l l m a g n e t i t e l o d e i n N o r t h P i t , M a g n e t s h o w i n g . 22 PLATE 2 . 9 . P a r a l l e l a p a t i t e r i c h z o n e s i n a s m a l l m a g n e t i t e l o d e , e a s t s i d e o f S o u t h P i t , Magnet s h o w i n g ( F i g . 2 . 3 A ) . PLATE 2.10. A p a t i t e c r y s t a l s g r o w i n g s m a l l m a g n e t i t e f r a g m e n t g r a p h ) . r a d i a l l y a r o u n d a ( i n c e n t r e o f p h o t o -23 t h e G l e n I r o n mine where o n l y a p a t i t e o c c u r s . Three p o l i s h e d s e c t i o n s ( d e t a i l e d d e s c r i p t i o n s : A p p e n d i x B) o f m a s s i v e m a g n e t i t e show a e u h e d r a l o r s u b h e d r a l g r a n u l a r t e x t u r e t o t h e o r e w i t h i n d i v i d u a l g r a i n s b e i n g 0.1 mm t o 0.5 mm a c r o s s . T r a i n s o f s p i n e l i n c l u s i o n s l e s s t h a n 30 m i c r o n s i n d i a m e t e r p a r a l l e l t h e g r a i n boundary ( P l a t e 2.11). E u h e d r a l m a g n e t i t e g r a i n s one t o f i v e m i l l i m e t r e s a c r o s s , s e e m i n g l y suspended i n m a s s i v e m a g n e t i t e a r e o c c a s i o n a l l y o b s e r v e d i n specimens f r o m A f t o n and a t t h e S i g n a l and A n v i l showings ( F i g . 2.2; Young and Uglow, 1926). When e t c h e d w i t h HBr one sample (#10) d i s p l a y e d an e x t r e m e l y f i n e c r y s t a l l o g r a p h e x c o l u t i o n t e x t u r e ( P l a t e 2.12). Presumably t h e e x s o l v e d m i n e r a l i s i l m e n i t e as t h i s sample had a h i g h e r t h a n a v e r a g e t i t a n i u m c o n t e n t . One sample (IM 32C) d i s p l a y e d a pr o m i n e n t c o l l o f o r m t e x t u r e ( P l a t e 2.13) d e f i n e d by t r a i n s o f s p i n e l (?) and r a d i a t i n g f r a c t u r e s . A d j a c e n t to the main dykes a r e numerous s u b - p a r a l l e l s m a l l e r d y k e l e t s commonly l e s s t h a n f i v e c e n t i m e t r e s a c r o s s ( P l a t e 2.14), and o f t e n abundant enough t o fo r m a c r i s s - c r o s s i n g network. Some dykes o f i n t e r -m e d i a t e s i z e ( t e n t o f i f t e e n c e n t i m e t r e s a c r o s s ) c o n t a i n numerous a n g u l a r t o subrounded i n c l u s i o n s o f h o s t r o c k , f o r m i n g b r e c c i a s ( P l a t e 2.15). S m a l l e r , m a r g i n a l m a g n e t i t e dykes a r e commonly e n c l o s e d by a one t o two m i l l i m e t r e w ide p o t a s s i c a l t e r a t i o n e n v e l o p e and o c c a s i o n a l l y c o n t a i n n a rrow e p i d o t e c o r e s ( P l a t e 2.16). C o u n t r y r o c k i n t h i s a r e a shows p e r v a s i v e e p i d o t e a l t e r a t i o n b u t shows no t h e r m a l a l t e r a t i o n . V e i n l e t s o f e p i d o t e a l s o c u t t h e m a g n e t i t e - e p i d o t e v e i n l e t s i n d i c a t i n g a p o s t - m a g n e t i t e m i n e r a l i z i n g e v e n t . S i m i l a r l y any s u l p h i d e 24 P L A T E 2 . 1 1 . P a r a l l e l t r a i n s o f s p i n e l ( ? ) i n c l u s i o n s r u n n i n g p a r a l l e l t o t h e b o u n d a r i e s o f t h e g r a i n a p p e a r i n g i n t h e l o w e r l e f t c o r n e r o f t h e p h o t o g r a p h ( s a m p l e # 8 ) ^ L e n g t h o f p o l i s h e d s e c t i o n i n p h o t o g r a p h i s 1.9 mm. P L A T E 2 . 1 2 . M i n u t e b l a d e s o f e x o l v e d i l m e n i t e ( ? ) ( d a r k b r o w n ) i n m a s s i v e m a g n e t i t e ( s a m p l e # 1 0 ) . L e n g t h o f p o l i s h e d s e c t i o n i n p h o t o g r a p h i s 0.12 mm. P L A T E 2 . 1 4 . P a r a l l e l m a g n e t i t e v e i n l e t s b o r d e r i n g e a s t s i d e o f S o u t h P i t , M a g n e t s h o w i n g ( F i g . 2.3A) 26 PLATE 2.15. M a g n e t i t e b r e c c i a b o r d e r i n g t h e m a i n l o d e o f Magnet s h o w i n g . PLATE 2 . 1 6 . M a g n e t i t e v e i n l e t ( 1 cm w i d e ) c o n t a i n i n g a c e n t r a l c o r e o f e p i d o t e . V e i n l e t b o r d e r s t h e m a i n l o d e i n S o u t h P i t , Magnet s h o w i n g ( F i g . 2 . 3 A ) . P L A T E 2 . 1 7 . C h a l c o p y r i t e l i n i n g a c a r b o n a t e f i l l e d v u g ( c e n t r e o f p h o t o g r a p h ) i n m a s s i v e m a g n e t i t e . S a m p l e I M 32E f r o m A f t o n d e p o s i t . 28 m i n e r a l i z a t i o n i s p o s t - m a g n e t i t e . F o r example, a t t h e Magnet showing p y r i t e and c h a l c o p y r i t e o c c u r as v e i n s a l o n g f r a c t u r e s i n m a g n e t i t e o r as v o i d f i l l i n g s i n b r e c c i a t e d m a g n e t i t e . Core from A f t o n has c h a l c o p y r i t e v e i n s f i l l i n g f r a c t u r e s t h r o u g h m a g n e t i t e - a p a t i t e d y k e s ; c h a l c o p y r i t e -b o r n i t e a l s o l i n e s vugs i n m a g n e t i t e ( P l a t e 2.17). I n g e n e r a l , m a g n e t i t e - a p a t i t e b o d i e s a t A f t o n a r e w e a k l y m i n e r a l i z e d , p r o b a b l y b e c a u s e t h e y c o n t a i n few f r a c t u r e s . L a t e s t a g e v e i n s o f d r u s y c a l c i t e c r o s s c u t m a g n e t i t e and s u l p h i d e m i n e r a l i z a t i o n . Supergene a l t e r a t i o n has r e s u l t e d i n h e m a t i t i z a t i o n o f m a g n e t i t e a l o n g f r a c t u r e s . 29 CHAPTER 3 MINOR ELEMENTS IN MAGNETITE 3.1 I n t r o d u c t i o n M i n o r e l e m e n t s i n m a g n e t i t e o c c u r i n t h r e e main f o r m s : +2 +3 (1) isomorphous s u b s t i t u t i o n s o f m e t a l i o n s f o r Fe and Fe ; (2) as c o n s t i t u e n t s o f ind e p e n d e n t m i n e r a l s produced by e x s o l u t i o n d u r i n g c o o l i n g ; and (3) as i n c l u s i o n s i n c o r p o r a t e d d u r i n g c r y s t a l l i z a t i o n . A ":*.:;; The f i r s t two forms a r e dependent on t h e c o n d i t i o n s o f f o r m a t i o n s o f t h e m a g n e t i t e w h i l e t h e l a s t 'one, u s u a l l y i s n o t . A s t u d y o f m a g n e t i t e from i n t r u s i v e r o c k s and c o n t a c t - m e t a s o m a t i c d e p o s i t s by C h i s t y a k o v (1970) c o n c l u d e d t h a t T i , V, Mn, Mg, Cr o c c u r m a i n l y i n e x s o l v e d m i n e r a l s . F o r examples T i might o c c u r i n u l v o s p i n e l , V c o u l s o n i t e , Mn i n j a c o b s i t e , and Mg i n s p i n e l . These m i n o r e l e m e n t s +2 +3 pre s u m a b l y formed isomorphous r e p l a c e m e n t s o f Fe and Fe when m a g n e t i t e f i r s t formed a t a h i g h e r t e m p e r a t u r e , but now o c c u r as i n d e p e n d e n t e x s o l v e d m i n e r a l s . E n t r y o f mi n o r e l e m e n t s i n m a g n e t i t e i s c o n t r o l l e d l a r g e l y by temperat and p r e s s u r e , c o m p o s i t i o n o f e n c l o s i n g magma o r aqueous s o l u t i o n , and p h y s i o - c h e m i c a l p r o p e r t i e s o f t h e i o n s ( F r i e t s c h , 1970; H a g g e r t y , 1976). The e f f e c t s o f t e m p e r a t u r e , p r e s s u r e and c o m p o s i t i o n a r e n o t w e l l known e x c e p t tha't t h e amount of s u b s t i t u t i o n o f most mi n o r e l e m e n t s i n c r e a s e s w i t h i n c r e a s e s i n t e m p e r a t u r e , p r e s s u r e , and a v a i l a b i l i t y o r c o n c e n t r a t i o n of e l e m e n t s ( C h i s t y a k o v , 1970). S i n c e s t r u c t u r e o f m a g n e t i t e and p h y s i o -c h e m i c a l p r o p e r t i e s o f s u b s t i t u t i n g i o n s a r e most e a s i l y d e f i n e d c r y s t a l 30 c h e m i s t r y has most commonly been used t o p r e d i c t e n t r y of m i n o r e l e m e n t s i n t o m a g n e t i t e . 3.2 M a g n e t i t e C r y s t a l C h e m i s t r y M a g n e t i t e , Fe304, i s an i n v e r s e s p i n e l w h i c h ca n be r e p r e s e n t e d by +3 IV +3 +2 V I t h e f o r m u l a (Fe ) (Fe Fe ) 0^ ( c f . n o r m a l s p i n e l w i t h g e n e r a l f o r m u l a ( R + 2 ) I V ( 2 R + 3 ) V I 0 4 ) . The m a g n e t i t e u n i t c e l l ( F i g . 3.1) i s f a c e - c e n t r e d c u b i c and c o n s i s t s o f 32 oxygen atoms i n a c u b i c c l o s e s t p a c k i n g arrangment c o n t a i n i n g 64 t e t r a h e d r a l i n t e r s t i c e s and 32 o c t a h e d r a l i n t e r s t i c e s . Of t h e 64 t e t r a h e d r a l i n t e r s t i c e s , 8 a r e +3 o c c u p i e d by Fe c a t i o n s and o f t h e 32 o c t a h e d r a l i n t e r s t i c e s , 16 a r e +3 +2 o c c u p i e d by 8 Fe and 8 Fe c a t i o n s . A l a r g e number o f e l e m e n t s a r e known t o s u b s t i t u t e f o r i r o n i n t h e +2 m a g n e t i t e s t r u c t u r e . Deer e t a l . (1974) r e p o r t t h a t c a l c i u m (Ca ) , +2 +2 +2 +2 manganese (Mn ) , magnesium (Mg ) , n i c k e l ( N i ) , c o b a l t (Co ) , and +2 +2 +3 z i n c (Zn ) can p a r t i a l l y r e p l a c e Fe , w h i t e chromium (Cr ) and vanadium +3 +3 (V ) can s u b s t i t u t e f o r Fe . At t e m p e r a t u r e s above a p p r o x i m a t e l y 600°C t h e r e i s s o l i d s o l u t i o n between m a g n e t i t e and u l v o s p i n e l ^ -f-Z|. ~r"2 ( ( F e ) ^ T i 0 4 ) i n v o l v i n g c o u p l e d s u b s t i t u t i o n o f T i and Fe f o r 2 F e + 3 . 3.3 G e n e r a l P r i n c i p l e s G o v e r n i n g M i n o r Element S u b s t i t u t i o n T hree b a s i c e m p i r i c a l r u l e s c o n t r o l l i n g e n t r y o f m i n o r e l e m e n t s i n t o a magmatic m i n e r a l were s u g g e s t e d by G o l d s c h m i d t (1937) on t h e a s s u m p t i o n 31 Oxygen Octahedra l cat ions © Tetrahedral cat ions "X" Origin F i g . 3.1. S t r u c t u r e o f t h e m a g n e t i t e u n i t c e l l ( f r o m L i n d s l e y , 1976) 32 t h a t b o n d i n g was p u r e l y i o n i c . These r u l e s a r e : (1) f o r two i o n s t o s u b s t i t u t e f o r one a n o t h e r t h e i o n i c r a d i i must not :'. d i f f e r by more t h a n 15 p e r c e n t . E l e m e nts w i t h t h e same r a d i i and c h a r g e w i l l e n t e r a m i n e r a l i n amounts p r o p o r t i o n a l t o t h e i r abundance; (2) when two i o n s have the same c h a r g e but d i f f e r e n t r a d i i , t h e i o n w i t h t h e s m a l l e r r a d i u s i s p r e f e r e n t i a l l y i n c o r p o r a t e d ; and (3) when two i o n s have s i m i l a r r a d i i b u t d i f f e r e n t c h a r g e s , the more h i g h l y c h a r g e d i o n i s p r e f e r e n t i a l l y i n c o r p o r a t e d . These r u l e s do n o t t a k e i n t o a c c o u n t c o v a l e n t b o n d i n g c h a r a c t e r i s t i c s , t h e r e f o r e , a g r e a t number of e x c e p t i o n s t o t h e s e r u l e s have been found. A more modern t h e o r y d e v e l o p e d t o a c c o u n t f o r c o v a l e n t b o n d i n g was p r o p o s e d by Ringwood (1955a; 1955b). H i s f o u r r u l e s f o r s u b s t i t u t i o n o f u n i v a l e n t , d i v a l e n t and l a r g e t r i v a l e n t i o n s were based on t h e p r e m i s e t h a t i o n s w i t h s m a l l e r e l e c t r o n e g a t i v i t i e s w o u l d f o r m s t r o n g e r , more i o n i c bonds because t h e l a r g e e l e c t r o n e g a t i v i t y of oxygen e n a b l e s i t t o b e t t e r a t t r a c t t h e v a l e n c y e l e c t r o n s o f t h e o t h e r i o n . H i s r u l e s a r e : • v ( l ) " f o r ' - . t w o f . i o n s ; : t o s i i b s t i t u t e f f o r one: a n o t h e r ; t h e '.ioriicTradii must no t -.•.differ by more':than .15 - p e r c e n t ; (2) whenever s u b s t i t u t i o n i s p o s s i b l e , t h e element w i t h t h e s m a l l e r e l e c t r o n e g a t i v i t y i s p r e f e r e n t i a l l y i n c o r p o r a t e d ; (3) f o r i o n s w i t h s i m i l a r c h a r g e s and e l e c t r o n e g a t i v i t i e s , t h e element w i t h t h e s m a l l e r r a d i u s i s p r e f e r e n t i a l l y i n c o p o r a t e d ; and 33 (4) f o r e l e m e n t s w i t h s i m i l a r e l e c t r o n e g a t i v i t i e s t h e i o n w i t h t h e g r e a t e r c h a r g e i s r e l a t i v e l y c o n c e n t r a t e d i n e a r l y c r y s t a l l a t e s . C u r t i s (1964) n o t e d t h a t f o r t h e t r a n s i t i o n m e t a l s , i o n i c r a d i i and e l e c t r o n e g a t i v i t y t r e n d i n o p p o s i t e d i r e c t i o n making i t d i f f i c u l t t o p r e d i c t from Ringwood's t h e o r y w h i c h e f f e c t w o u l d be t h e g r e a t e r . F o r t h e s e e l e m e n t s , t h e r e f o r e , he used c r y s t a l f i e l d t h e o r y ( e . g . as d e s c r i b e d by B u r n s , 1970) w h i c h p r e d i c t s t h a t c e r t a i n t r a n s i t i o n m e t a l i o n s w i l l be s t a b i l i z e d r e l a t i v e t o a f r e e i o n when p l a c e d i n an o c t a h e d r a l o r t e t r a -h e d r a l f i e l d . The energy d i f f e r e n c e between a t r a n s i t i o n m e t a l i o n i n a s p h e r i c a l c h a r g e f i e l d and one i n o c t a h e d r a l o r t e t r a h e d r a l c o - o r d i n a t i o n i s known as t h e c r y s t a l - f i e l d s t a b i l i z a t i o n e nergy. On t h i s b a s i s C u r t i s (1964) p r e d i c t e d t h a t t r a n s i t i o n m e t a l i o n s w i t h l a r g e r s t a b i l i z a t i o n e n e r g i e s would be p r e f e r e n t i a l l y i n c o r p o r a t e d i n t o a c r y s t a l o v e r t h o s e i o n s w i t h l o w e r s t a b i l i z a t i o n e n e r g i e s . N o c k o l d s (1966) a l s o r e c o g n i z e d t h e d i f f i c u l t i e s w i t h G o l d s c h m i d t ' s and Ringwood's r u l e s . He chose t o combine c h a r g e , r a d i u s and e l e c t r o n e g a t i v i t y i n t o a s i n g l e f u n c t i o n c a l l e d b o n d i n g energy. The b o n d i n g energy of a bond A-B e q u a l s t h e c o v a l e n t e n e r g y ^ _ ^ p l u s t h e i o n i c r e s o n a n c e e n e r g y ^ _ ^ . U s i n g f o r m u l a s d e v e l o p e d f o r the c a l c u l a t i o n o f t h e c o v a l e n t e nergy o f a s i n g l e bond and t h e e l e c t r o n e g a t i v i t y d i f f e r e n c e d i v i d e d by bond l e n g t h f o r t h e i o n i c s t r e n g t h term, N o c k o l d s d e v e l o p e d an e m p i r i c a l f o r m u l a g i v i n g bond energy i n c r y s t a l s . The c a t i o n h a v i n g t h e g r e a t e s t c a l c u l a t e d b o n d i n g energy i s p r e f e r e n t i a l l y i n c o r p o r a t e d . A l l t h e above r u l e s have been r e v i e w e d and c r i t i c i z e d by Burns and 34 F y f e (1967) on t h e b a s i s t h e y have been d e s i g n e d t o f i t o n l y c e r t a i n d a t a and t h a t t h e y do n o t c o n s i d e r a l l phases i n v o l v e d . Ringwood (1955a; 1955b), i n p a r t i c u l a r , has been c r i t i c i z e d by Burns and F y f e ( i b i d . ) f o r assuming i o n i c bonds t o be s t r o n g e r t h a n c o v a l e n t bonds based on m e l t i n g p o i n t d a t a f o r d i s c r e t e i s o s t r u c t u r a l p a i r s . There i s much d i s a g r e e m e n t as t o w h i c h bond i s s t r o n g e r , t h e r e f o r e , e x t r a p o l a t i o n o f t h e s e c o n c l u s i o n s t o o t h e r compounds such as m a g n e t i t e can o n l y be done w i t h g r e a t u n c e r t a i n t y . Of t h e r u l e s g i v e n h e r e t h o s e based on s t a b i l i z a t i o n e n e r g i e s ( C u r t i s , 1964) a r e p r o b a b l y most a p p l i c a b l e t o t h i s p r e s e n t s t u d y as t h e y were d e s i g n e d t o f i t t r a n s i t i o n m e t a l s as a r e t h e m a j o r i t y of e l e m e n t s c o n s i d e r e d i n t h i s s t u d y . W i t h t h e above l i m i t a t i o n s i n mind, v a l u e s of p a r a m e t e r s of s i g n i f i c a n c e i n p r e d i c t i n g t h e a b i l i t y o f one i o n t o s u b s t i t u t e r e l a t i v e t o a n o t h e r one a r e summarized i n T a b l e 3.1. F i v e p r o p e r t i e s , namely i o n i c r a d i u s , e l e c t r o n e g a t i v i t y , r e l a t i v e t o t a l b o n d i n g e n e r g y , and s t a b i l i z a t i o n energy a r e l i s t e d f o r 12 i o n s commonly f o u n d i n m a g n e t i t e . These p r o p e r t i e s a r e used l a t e r i n t h i s t h e s i s ( S e c t i o n 3.4.1) t o p r e d i c t m i n o r element b e h a v i o u r i n m a g n e t i t e d u r i n g c r y s t a l l i z a t i o n o f a magma. 3.4 M i n o r Element S u b s t i t u t i o n i n M a g n e t i t e E n t r y o f m i n o r e l e m e n t s i n t o m a g n e t i t e c a n be p r e d i c t e d based on e m p i r i c a l r u l e s o u t l i n e d i n S e c t i o n 3.3. T h e o r e t i c a l r e s u l t s a r e compared t o p u b l i s h e d a n a l y t i c a l d a t a c o m p i l e d f o r r e f e r e n c e i n T a b l e 3.2. Comparisons a r e l i m i t e d by t h e v a r i a b l e s o u r c e s and v a r i a b l e e q u a l i t y o f d a t a . R e f e r e n c e t o T a b l e 3.1 s h o u l d be made f o r p r o p e r t i e s of i o n s r e f e r r e d t o below. TABLE 3.1 PROPERTIES OF IONS WHICH EOTTER MAGNETITE STRUCTURE Ion I o n i c Radius ( A ) 1 E l e c t r o n e g a t i v i t y2 Bonding E n e r g y 3 O c t a h e d r a l S t a b i l i z a t i o n Energy 4 T e t r a h e d r a l C o o r d i n a t i o n O c t a h e d r a l C o o r d i n a t i o n F E + 3 0.49 0 . 6 5 1 .8 246 0 F E + 2 . 5 0.78 1 .65 178 11.4 . . C r + 3 - 0 . 6 2 1.6 321 6 0 . 0 T 1 + 4 - 0.61 1 .6 348 -V+3 • - 0 . 6 4 1.4 299 4 1 . 0 N i + 2 - 0 . 6 9 1 . 8 197 2 9 . 3 Mg+Z - 0.72 1.2 202 -Cu + 2 - 0.73 2 . 0 - n e g a t i v e Zn+Z 0 . 6 0 0.74 1 .5 170 -M n + 2 - 0 . 8 3 1 .4 174 0 Co + 2 - 0 . 7 5 1.7 183 17.1 Pb + Z - 1.19 1 .6 138 1: Shannon and P r e w i t t , 1969. 2 : Ringwood, 1955a.. 3 : N o c k o l d s , 1966. 4 : C u r t i s , 1963. 5 : D o e s n ' t occur or no i n f o r m a t i o n a v a i l a b l e i n r e f e r e n c e s 1 t o 36 TABLE 3.2 RANGE OF MINOR ELEMENT ABUNDANCES IN'MAGNETITE  FROM INTRUSIVE ROCKS OF DIFFERING COMPOSITION ( v a l u e s i n ppm; a l l d a t a from F r i e t s c h (1970) u n l e s s o t h e r w i s e i n d i c a t e d ) MINOR ELEMENT ACID INTRUSIVE COMPOSITION .-'INTERMEDIATE "BASIC ULTRABASIC Cr T i V N i Mg Cu Zn Mn Co Pb 250-2000 1000-16680 150-4000 <2-500 N.D. 8-64 2 <25-2500 390-850 5- 500 6- 17 200-4500 1140-44460 1250-6000 10-3000 480-660 N.D. ^25-200 230-3100 40-300 10-80 0-15000 34000-54000 1020-177960 1200-25200 1 0-14000 <2-3100 360-31080 20-600 < 25-4000 0-9060 3-1000 <10-45 N.D. 900-81400 17100-90600 N.D. N.D. 1160-2010 N.D. N.D. 1: N.D. means d a t a i s too s p a r s e o r i s n o t a v a i l a b l e . 2: V a l u e s from O s t a f i y c h u k e t a l . , 1973. 37 3.4.1 B e h a v i o u r o f M i n o r Elements i n M a g n e t i t e Chromium -+3 +3 Chromium i o n (Cr ) s u b s t i t u t e s f o r Fe because i t has a v e r y s i m i l a r r a d i u s when i n o c t a h e d r a l c o - o r d i n a t i o n . Chrome c o n c e n t r a t i o n i n e a r l y d i f f e r e n t i a t e s i s a r e s u l t o f t h e s m a l l e r e l e c t r o n e g a t i v i t y ( r e l a t i v e t o +3 Fe ) , h i g h t o t a l b o n d i n g energy and t h e v e r y h i g h s t a b i l i z a t i o n energy. Thus, chromium e n r i c h m e n t i n b a s i c r o c k s i s t o be e x p e c t e d and i s e v i d e n t i n m a g n e t i t e t r a c e element d a t a c o m p i l e d by F r i e t s c h . (1970) and C h i s t y a k o v (1975). T i t a n i u m +2 +2 T i t a n i u m i o n ( T i ) and Fe f o r char g e b a l a n c e ( S e c t i o n 3.2) +3 s u b s t i t u t e s for::2Fe h a v i n g a s i m i l a r i o n i c r a d i u s . V a l u e s f o r e l e c t r o -n e g a t i v i t y and b o n d i n g energy s u g g e s t t h a t m a g n e t i t e w i l l be e n r i c h e d i n t i t a n i u m a t an e a r l y s t a g e of c r y s t a l l i z a t i o n . F r i e t s c h (1970) and C h i s t y a k o v (1975) c o n f i r m e d t h a t t h e t i t a n i u m c o n t e n t o f m a g n e t i t e i s h i g h e s t i n b a s i c r o c k s . Vanadium +3 Vanadium i o n (V ) has an i o n i c r a d i u s a l m o s t i d e n t i c a l t o t h a t o f +3 Fe , and t h e r e f o r e , can be e x p e c t e d t o s u b s t i t u t e f o r i t . E l e c t r o n e g a t i v i t y and s t a b i l i z a t i o n e n ergy b o t h i n d i c a t e t h a t vanadium s h o u l d be c o n c e n t r a t e d i n e a r l y c r y s t a l l a t e s o f m a g n e t i t e i n b a s i c and u l t r a b a s i c r o c k s . Data o f F r i e t s c h (1970) and C h i s t y a k o v (19 75) c o n f i r m t h i s t r e n d . 33 N i c k e l +2 +2 N i c k e l i o n ( N i ) s u b s t i t u t e s f o r Fe . E l e c t r o n e g a t i v i t y f o r n i c k e l +3 +2 ( N i ) i s g r e a t e r t h a n Fe s u g g e s t i n g l a t e e n r i c h m e n t o f n i c k e l would be f a v o u r e d . However, b o n d i n g and s t a b i l i z a t i o n e n e r g i e s i n d i c a t e e a r l y e n r i c h m e n t o f n i c k e l . S i n c e e a r l y e n r i c h m e n t i n m a g n e t i t e i s g e n e r a l l y f o u n d t h e l a t t e r c h a r a c t e r i s t i c s appear t o be o v e r r i d i n g i m p o r t a n c e . Magnesium +2 +2 Magnesium i o n (Mg ) s u b s t i t u t e s f o r Fe . E l e c t r o n e g a t i v i t y and b o n d i n g energy i n d i c a t e e a r l y e n r i c h m e n t of magnesium i n m a g n e t i t e . T h i s i s c o n f i r m e d by F r i e t s c h (1970). C o b a l t +2 +2 C o b a l t i o n (Co ) s u b s t i t u t e s f o r Fe h a v i n g a v e r y s i m i l a r r a d i u s . B o n d i n g energy and s t a b i l i z a t i o n e nergy f o r c o b a l t i o n a r e g r e a t e r t h a n +2 t h o s e f o r Fe , t h e r e f o r e , e a r l y e n r i c h m e n t i s i n d i c a t e d . D a t a on "cobalt i n F r i e t s c h (1970) i s t o o s p a r s e t o c o n f i r m o r c o n t r a d i c t t h i s t r e n d . Copper +2 +2 Copper i o n (Cu ) s u b s t i t u t e s f o r Fe . Due t o a h i g h e r e l e c t r o -+2 +2 n e g a t i v i t y t h a n Fe , Cu presumably forms weaker more c o v a l e n t bonds i n t h e m a g n e t i t e s t u r c t u r e . T h i s , p l u s a n e g a t i v e s t a b i l i z a t i o n energy i n d i c a t e s c o pper s h o u l d be e n r i c h e d i n m a g n e t i t e i n l a t e d i f f e r e n t i a t e s 39 as i s f o u n d i n t h e S k a e r g a a r d complex (Wager and M i t c h e l l , 1951). Data i n T a b l e 3.2 i s t o o s p a r s e t o i n d i c a t e a t r e n d . Z i n c +2 +2 Z i n c i o n (Zn ) s u b s t i t u t e s f o r Fe . E v i d e n c e f o r s u b s t i t u t i o n o f +2 Fe by z i n c i o n i s c o n t r a d i c t o r y as b o t h e l e c t r o n e g a t i v i t y and b o n d i n g +2 . e n ergy f o r z i n c a r e s m a l l e r t h a n t h o s e f o r Fe . No p r e d i c t i o n s t h e r e f o r e , can be made; however, d a t a i n F r i e t s c h (1970) i n d i c a t e s e n r i c h m e n t o f z i n c i n m a g n e t i t e from b a s i c r o c k s . . Manganese +2 +2 Manganese i o n (Mn ) s u b s t i t u t e s f o r Fe d e s p i t e t h e s l i g h t l y l a r g e r +2 r a d i u s o f manganese i o n . B o t h manganese i o n and Fe have a p p r o x i m a t e l y t h e same b o n d i n g e n e r g y , b u t t h e s l i g h t l y l o w e r e l e c t r o n e g a t i v i t y o f manganese i o n i n d i c a t e s t h a t i t s h o u l d be s l i g h t l y e n r i c h e d i n e a r l y d i f f e r e n t i a t e s . F r i e t s c h (1970) and C h i s t y a k o v (1975) c o n f i r m e d t h i s t o be g e n e r a l l y t h e c a s e , however, C h i s t y a k o v a l s o found e n r i c h m e n t o f manganese i n m a g n e t i t e f r o m a l k a l i c r o c k s . Lead +2 +2 Lead i o n (Pb ) has an i o n i c r a d i u s q u i t e d i f f e r e n t f r o m Fe and +3 Fe w h i c h s h o u l d r e s u l t i n no s u b s t i t u t i o n . I n c o n t r a d i c t i o n t o t h i s p r e d i c t i o n s m a l l amounts do o c c u r i n m a g n e t i t e ( F r i e t s c h , 1970). 40 I t must be emphasized t h a t t h e s e p r e d i c t e d , g e n e r a l t r e n d s a p p l y o n l y t o t h e v a r i a t i o n i n abundance o f i n d i v i d u a l i o n s i n m a g n e t i t e d u r i n g d i f f e r e n t i a t i o n o f a magma. They cannot be used q u a n t i t a t i v e l y , as t h e a b s o l u t e abundance, o f i o n s e n t e r i n g a c r y s t a l w i l l depend on v a r i o u s f a c t o r s s u c h as t h e i r abundance i n t h e s o u r c e magma, magmatic c o m p o s i t i o n , t e m p e r a t u r e , and p r e s s u r e . Comparison o f m a g n e t i t e a n a l y s i s may be d i f f i c u l t because t h e s e f a c t o r s cause t h e abundance o f min o r e l e m e n t s i n m a g n e t i t e t o be e x t r e m e l y v a r i a b l e even between s i m i l a r r o c k t y p e s . T h i s v a r i a b i l i t y m i g h t be r e d u c e d by u s i n g r a t i o s o f m i n o r e l e m e n t s . 3.4.2 A p p l i c a t i o n o f Element R a t i o s i n M a g n e t i t e M e t a l r a t i o s have been used t o i n d i c a t e t h e s t a g e o f d i f f e r e n t i a t i o n of a magma and t h e o r i g i n o f m e t a l d e p o s i t s ( e . g . L a n d e r g r e n , 1948; D a v i d s o n , 1962). R a t i i o s a r e used commonly because t h e i r n u m e r i c a l v a l u e i s n o t dependent on a b s o l u t e abundances o f i o n s . Thus, t h e y might be more comparable from i n t r u s i v e t o i n t r u s i v e , o r f r o m d e p o s i t t o d e p o s i t t h a n abundance o f m i n o r e l e m e n t s . Some o f t h e more common r a t i o s examined i n m a g n e t i t e i n t h e l i t e r a t u r e a r e C o / N i , T i / V and V/Zn. +2 Due t o t h e d i f f e r i n g a b i l i t y o f t h e i o n s t o s u b s t i t u t e f o r Fe +3 and Fe ( S e c t i o n s 3.2 and 3.4.1) t h e s e r a t i o s i n m a g n e t i t e can be e x p e c t e d t o v a r y d u r i n g d i f f e r e n t i a t i o n o f a magma. As examples: C o / N i , T i / V , N i / C r and Mn/Zn t r e n d s i n m a g n e t i t e a r e p r e d i c t e d below. R a t i o o f N i / C r i s used l a t e r i n t h i s t h e s i s ( S e c t i o n 5.5.3) i n i n t e r p r e t a t i o n s o f th e g e n e s i s o f m a g n e t i t e l o d e s i n t h e I r o n Mask b a t h o l i t h . 41 C o/Ni R a t i o i n M a g n e t i t e +2 +2 The r a t i o of Co / N i i n m a g n e t i t e i s p r e d i c t e d t o i n c r e a s e d u r i n g c r y s t a l l i z a t i o n o f a magma. B o t h c o b a l t and n i c k e l i o n s a r e e n r i c h e d i n e a r l y c r y s t a l f r a c t i o n s , however, t h e h i g h e r b o n d i n g energy and s t a b i l i z a t i o n e n e rgy o f n i c k e l c auses n i c k e l t o be d e p l e t e d f r o m t h e magma a t a f a s t e r r a t e t h a n c o b a l t . T h i s r e s u l t s i n i n c r e a s e o f t h e Co/Ni r a t i o d u r i n g c r y s t a l l i z a t i o n . T i / V R a t i o i n M a g n e t i t e B e h a v i o u r o f T i + 4 / V + 3 i n m a g n e t i t e d u r i n g d i f f e r e n t i a t i o n i s n o t c l e a r . ; T h i s i s p r o b a b l y due t o c o m p l i c a t i o n s caused by c o u p l e d s u b s t i t u t i o n o f T i + 4 and F e + 2 f o r 2 F e + 3 . Hegemann and A l b r e c h t (1954) used T i / V r a t i o s t o c l a s s i f y i r o n o r e d e p o s i t s . They found i r o n o r e s i n magmatic r o c k s t o have a T i / V r a t i o o f 2.9, c o n t a c t - m e t a s o m a t i c and i n t r a - m a g m a t i c i r o n d e p o s i t s t o have a r a t i o g r e a t e r t h a n 2.9, and o t h e r i r o n d e p o s i t s ( e . g . h y d r o t h e r m a l , s e d i m e n t a r y - e x h a b i t i v e ) t o have a r a t i o l e s s t h a n 2.9. V/Zn R a t i o i n M a g n e t i t e +3 +2 D u r i n g c r y s t a l l i z a t i o n t h e V /Zn r a t i o i n m a g n e t i t e t e n d s t o d e c r e a s e . Because t h e s e i o n s compete f o r d i f f e r e n t s i t e s , p r e f e r e n t i a l i n c o r p o r a t i o n o f vanadium i n t o t h e m a g n e t i t e s t r u c t u r e i s a r e s u l t o f e l e c t r o n e g a t i v i t y and b o n d i n g energy d i f f e r e n c e s b e i n g g r e a t e r between 42 vanadium (V ) and i r o n (Fe ) t h a n between z i n c (Zn ) and i r o n (Fe ) . F r i e t s c h (1970) found a V/Zn r a t i o o f 10 o r g r e a t e r f o r magmatic i r o n o x i d e s , and a r a t i o between 1.25 and 10 f o r v o l c a n i c s e d i m e n t a r y and met a s o m a t i c i r o n o x i d e s . N i / C r R a t i o i n M a g n e t i t e +2 +3 The r a t i o o f N i /Cr i n m a g n e t i t e s h o u l d i n c r e a s e d u r i n g +3 d i f f e r e n t i a t i o n o f a magma. As a r e s u l t o f Cr h a v i n g a h i g h e r c h a r g e , s m a l l e r radius,- s m a l l e r e l e c t r o n e g a t i v i t y , h i g h e r b o n d i n g energy and + 2 + 3 h i g h e r s t a b i l i z a t i o n energy t h a n N i , Cr w i l l be d e p l e t e d a t a f a s t e r +2 r a t e t h a n N i c a u s i n g t h e r a t i o t o r i s e . Mn/Zn R a t i o i n M a g n e t i t e +2 +2 E v i d e n c e f o r p r e d i c t i n g Mn /Zn b e h a v i o u r i n m a g n e t i t e i s +2 +2 c o n t r a d i c t o r y . Zn has a s m a l l e r r a d i u s t h a n Mn ; on t h e o t h e r hand, +2 Zn has a h i g h e r e l e c t r o n e g a t i v i t y and s m a l l e r b o n d i n g energy t h a n +2 Mn . D a t a i n F r i e t s c h (1970) i n d i c a t e s s t r o n g e r e n r i c h m e n t o f Zn o v e r Mn i n m a g n e t i t e i n e a r l y d i f f e r e n t i a t e s , t h e r e f o r e , on an e m p i r i c a l b a s i s , t h e r a t i o a p p a r e n t l y i n c r e a s e s d u r i n g d i f f e r e n t i a t i o n . 43 CHAPTER 4 SAMPLING AND ANALYTICAL PROCEDURES 4.1 I n t r o d u c t i o n S i x t e e n samples o f m a s s i v e and d i s s e m i n a t e d m a g n e t i t e numbered 1 t o 15, and 1M 1 ( F i g . 2.2) were c o l l e c t e d d u r i n g he F a l l o f 1975 from t h e I r o n Mask b a t h o l i t h f o r an u n d e r g r a d u a t e t h e s i s w h i c h was n e v e r c o m p l e t e d . F o r t h i s p r e s e n t s t u d y t h e above c o l l e c t i o n was augmented i n September 1976 and 1977 by 36 a d d i t i o n a l samples o f m a g n e t i t e ( F i g . 2.2: numbers 1M 10 t o 1M 3 5 ) . Samples were c o l l e c t e d f o r s e p a r a t i o n and c o n c e n t r a t i o n o f m a g n e t i t e t o be a n a l y s e d f o r m i n o r e l e m e n t s . Two samples (1M 21 and 1M 22) were made up o f a t o t a l o f 23 c h i p samples t a k e n a t 30 cm (one f o o t ) i n t e r v a l s a c r o s s t h e w i d t h o f t h e main exposed l o d e a t two l o c a t i o n s ( F i g . 2.3a; P l a t e s 4.1 and 4.2); t h e s e samples were t a k e n t o g i v e an a v e r a g e m i n o r element c o n t e n t f o r t h e main l o d e and t o i n d i c a t e any c o m p o s i t i o n a l z o n i n g i n t h e l o d e s . Most o f t h e s e m a g n e t i t e samples show mi n o r m a r t i t i z a t i o n a l o n g f r a c t u r e s and numerous f i n e s p i n e l i n c l u s i o n s (specimen d e s c r i p t i o n s : A p p e n d i x B) w h i c h i n most c a s e s amount t o o n l y t h r e e t o f i v e p e r c e n t o f t h e sample volume. Samples, shown on F i g s . 2.1J, 2.2 and 2.3a,b (sample t y p e and c o -o r d i n a t e s : A p p e n d i x A) a r e t a b u l a t e d by t y p e i n T a b l e 4.1. About h a l f t h e samples a r e fr o m m a s s i v e m a g n e t i t e l o d e s , t h e o t h e r h a l f a r e fr o m d i s s e m i n a t e d m a g n e t i t e i n i g n e o u s r o c k s . PLATE 4.2. L o c a t i o n o f c h i p s a m p l e s IM 21-0 to 11. F a c e o f m a i n l o d e , C e n t r a l P i t o f Magnet s h o w i n g ( F i g . 2 . 3 B ) . 45 TABLE 4.1 DISTRIBUTION OF SAMPLES BY MAGNETITE FORM  AND HOST MAGNETITE HOST NUMBER OF DEPOSITS NUMBER OF TYPE ROCK OR SAMPLE LOCATIONS SAMPLES SYENITE 2 5 MASSIVE DIORITE 2 33 PICRITE 7 7 DISSEM- SYENITE 8 11 INATED... .. . DIORITE 7 9 MISCEL- 4 4 LANEOUS TOTAL 31 69 4.2 S a m p l i n g Methods and Sample P r e p a r a t i o n A d e t a i l e d d e s c r i p t i o n o f s a m p l i n g methods and c o n c e n t r a t i o n p r o c e d u r e s i s g i v e n i n A p p e n d i x C; o n l y a b r i e f d e s c r i p t i o n o f methods i s g i v e n h e r e . Samples c o l l e c t e d f o r m a g n e t i t e s e p a r a t i o n and a n a l y s i s were chosen f r o m r o c k s a p p a r e n t l y f r e e o f h y d r o t h e r m a l a l t e r a t i o n i n o r d e r t o a v o i d s e c o n d a r y , h y d r o t h e r m a l m a g n e t i t e . A p p r o x i m a t e l y 10 pounds o f f i s t -s i z e d p i e c e s were c o l l e c t e d f r o m each sample s i t e w i t h t h e a i d o f a sledge-hammer and c h i s e l . A t e i g h t sample s i t e s two s e p a r a t e samples were c o l l e c t e d t o t e s t t h e v a r i a b i l i t y o f d a t a f r o m s a m p l i n g ; t h i s a n a l y s i s i s d e s c r i b e d f u r t h e r i n S e c t i o n 4.5 and d e t a i l e d i n App e n d i x C . l . 46 M a g n e t i t e s e p a r a t i o n and c o n c e n t r a t i o n , t h e most i m p o r t a n t s t e p , t u r n e d out t o be e x t r e m e l y t i m e consuming and much more d i f f i c u l t t h a n e x p e c t e d . D e t a i l s o f t h e p r o c e d u r e s used a r e d e s c r i b e d i n A p p e n d i x C.2. B r i e f l y a l l samples, i n i t i a l l y c r u s h e d i n a jaw and cone c r u s h e r , were t h e n p u l v e r i z e d between c e r a m i c p l a t e s u n t i l t h e sample p a s s e d t h r o u g h a 100 mesh n y l o n s i e v e . M a s s i v e m a g n e t i t e w i t h l i t t l e gangue was most e a s i l y c o n c e n t r a t e d by u s i n g a r e p e a t e d c y c l e o f u n d e r w a t e r m a g n e t i c s e p a r a t i o n and g r i n d i n g by hand w i t h c e r a m i c m o r t a r and p e s t l e ( o r by m o t o r i z e d a g a t e m o r t a r ) u n t i l t h e d e s i r e d p u r i t y ( s 95 volume p e r c e n t ) o f m a g n e t i t e was a t t a i n e d . M a g n e t i t e d i s s e m i n a t e d i n i n t r u s i v e r o c k s and m a s s i v e m a g n e t i t e w i t h abundant gangue p r o v e d more d i f f i c u l t t o c o n c e n t r a t e . The most s a t i s f a c t o r y method i n v o l v e d : (1) rough m a g n e t i c s e p a r a t i o n u s i n g an E r i e z L a b o r a t o r y Model (L-8) Wet Drum M a g n e t i c S e p a r a t o r ; (2) d e n s i t y s e p a r a t i o n i n Bromoform ( i f n e c e s s a r y t h i s s t e p was sometimes r e p e a t e d a f t e r g r i n d i n g o f s a m p l e ) ; (3) r e p e a t e d u n d e r w a t e r s e p a r a t i o n w i t h a r e t r a c t a b l e hand magnet a l t e r n a t i n g w i t h g r i n d i n g o f sample w i t h c e r a m i c m o r t a r and p e s t l e u n t i l t h e d e s i r e d p u r i t y was a t t a i n e d . C o n t a m i n a t i o n i n m a g n e t i t e c o n c e n t r a t e s was e s t i m a t e d by p o i n t c o u n t i n g p o l i s h e d g r a i n mounts o f n i n e random samples. A p p r o x i m a t e volume p e r c e n t and w e i g h t p e r c e n t c o n t a m i n a t i o n a r e shown i n T a b l e 4.2. C o n t a m i n a t i o n f o r a l l samples e x c e p t 11B i s l e s s t h a n t h e f i v e p e r c e n t a r b i t r a r i l y d e f i n e d as a c c e p t a b l e , however, sample 11B shows t h a t c o n t a m i n a t i o n 47 occasionally reached s i g n i f i c a n t amounts and could be a source of anomalous amounts of minor elements. Results of minor elements tested for t h i s sample, however, (Appendix C) are very s i m i l a r to r e s u l t s for the duplicate sample 11A, i n d i c a t i n g contamination up to 10 volume percent does not se r i o u s l y a f f e c t a n a l y t i c a l r e s u l t s . This lack of e f f e c t i s mainly due to the, low amounts of elements being analysed f o r i n contaminating s i l i c a t e s such as feldspar and quartz. TABLE 4.2 POINT COUNT ESTIMATES OF MAGNETITE CONCENTRATE CONTAMINATION SAMPLE TYPE VOLUME % CONTAMINANTS WEIGHT % CONTAMINANTS ' 2 Massive 1.5 0.8 3A Massive 0.5 0.3 4A Massive 0.5 0.3 7 Disseminated 3.5 1.8 11B Disseminated 10.5 5.5 141 Massive 2.0 1.0 142 Massive 2.0 1.0 1M21-10 Massive 4.0 2.1 1M28 Disseminated 3.5 1.8 1: Weight percent contaminants was calculated from volume percent using p magnetite = -5.2 and JO contaminants = 2.7 48 4.3 A n a l y t i c a l P r o c e d u r e s 4.3.1,. A t o m i c A b s o r p t i o n A t o m i c a b s o r p t i o n s p e c t r o m e t r y was used t o g i v e q u a n t i t i v e a n a l y s e s of m a g n e t i t e f o r c o b a l t , chromium, c o p p e r , magnesium, manganese, n i c k e l , l e a d , t i t a n i u m , vanadium and z i n c . A V a r i o n - T e c h t r o n AA-4 u n i t was used t o d e t e r m i n e chromium, c o p p e r , magnesium, manganese, vanadium, and z i n c ? , and a B e r k i n - E l m e r model 303 u n i t w i t h b ackground c o r r e c t i o n was used t o d e t e r m i n e c o b a l t , n i c k e l and l e a d . P r o c e d u r e s used were s i m i l a r t o t h o s e d e s c r i b e d i n F l e t c h e r ( 1 9 7 0 ) . T i t a n i u m i n s o l u t i o n s was d e t e r m i n e d a t a c o m m e r c i a l l a b o r a t o r y . ^ Ions were put i n t o s o l u t i o n by d i g e s t i n g one gram o f m a g n e t i t e i n a l t e r n a t e l y h o t c o n c e n t r a t e d h y d r o c h l o r i c and h o t n i t r i c a c i d and f i n a l l y i n a s o l u t i o n o f c o n c e n t r a t e d n i t r i c a c i d and 6M h y d r o c h l o r i c a c i d (Nakagawa, 1975). D i g e s t i o n s were c o m p l e t e e x c e p t f o r chromium r i c h s p i n e l s f r o m p i c r i t e w h i c h were sometimes o n l y 50 p e r c e n t d i g e s t e d . I n t e r f e r e n c e from i r o n i n a n a l y s i s f o r c o b a l t , chromium, n i c k e l , t i t a n i u m and z i n c (Angino and B i l l i n g s , 1967) was a v o i d e d by r e m o v a l o f i r o n from s o l u t i o n u s i n g s o l v e n t e x t r a c t i o n (Nakagawa, i b i d . ) . D e t a i l s o f a n a l y t i c a l p r o c e d u r e a r e g i v e n i n A p p e n d i x C.2. S t a n d a r d s o l u t i o n s were p r e p a r e d i n t h e range z e r o t o e i g h t ppm and s u b j e c t e d t o t h e same s o l v e n t e x t r a c t i o n p r o c e d u r e as t h e s a m p l e s , t h u s , s m a l l l o s s e s of i o n s w i t h i r o n was compensated f o r . Computer c a l c u l a t e d c a l i b r a t i o n c u r v e s c o n v e r t e d a b s o r b a n c e t o c o n c e n t r a t i o n s . S o l u t i o n s p r e p a r e d a t t h e Dept. o f G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h C o l u m b i a , were a n a l y s e d f o r t i t a n i u m by a t o m i c a b s o r p t i o n a t Min-En L a b o r a t o r i e s L t d . , N o r t h V a n c o u v e r , B r i t i s h C o l u m b i a , on May 1, 1978. 49 4.3.2. M i c r o p r o b e E l e c t r o n - p r o b e a n a l y s i s o f 15 samples was c a r r i e d out on p o l i s h e d t h i n s e c t i o n s and p o l i s h e d g r a i n mounts t o d e t e r m i n e m a g n e t i t e c o m p o s i t i o n t o compare w i t h a t o m i c a b s o r p t i o n r e s u l t s and t o c heck c r y s t a l l o g r a p h i c homogeneity. One sample o f a p a t i t e (1M31) was a n a l y s e d . A n a l y s e s were done w i t h an ARL-SEMQ i n s t r u m e n t under t h e f o l l o w i n g a n a l y t i c a l c o n d i t i o n s : 15kv a c c e l e r a t i n g v o l t a g e , 10 um beam d i a m e t e r (26 ym f o r a p a t i t e ) , 40 uA beam c u r r e n t (60 uA f o r a p a t i t e ) and 10 second c o u n t i n g t i m e s . S t a n d a r d s used f o r m a g n e t i t e a n a l y s e s were: h e m a t i t e f o r Fe, r u t i l e f o r T i , e s k o l i t e f o r C r , s p e s s a r t i n e f o r Mn (37.04 w e i g h t p e r c e n t ) , a n d a l u s i t e f o r A l , f o r s t e r i t e f o r Mg, w o l l a s t o n i t e f o r Ca and S i , and vanadium g r o s s u l a r f o r V (2.24 w e i g h t p e r c e n t ) . B a c kground, d e a d t i m e , a b s o r p t i o n , a t o m i c number and f l u o r e s c e n c e c o r r e c t i o n s were a p p l i e d t o m a g n e t i t e a n a l y s e s u s i n g a computer program d e v e l o p e d by R u c k l i d g e and G a s p e r r i n i ( 1 9 6 9 ) . I n t e r f e r e n c e from t i t a n i u m i n t h e a n a l y s i s o f vanadium ( S n e t s i n g e r e t a l . , 1968) was e m p i r i c a l l y c o r r e c t e d by u s i n g t h e f o r m u l a : Vcps = . - V_ . , - ( T i _ . - T i ,) x 0.0232 Peak c o u n t s Background Peak c o u n t s Background where: V = vanadium, cps = c o u n t s p e r s e c o n d , T i = t i t a n i u m . T o t a l i r o n d e t e r m i n e d as FeO was r e c a l c u l a t e d i n t o FeO and ¥e20^ by assuming s p i n e l s t o i c h i o m e t r y ( C a r m i c h a e l , 1967). A d d i t i o n a l s t a n d a r d s used f o r a p a t i t e a n a l y s i s were: p h l o g o p i t e f o r F (9.04 w e i g h t p e r c e n t ) , and a p a t i t e f o r P (40.88 w e i g h t p e r c e n t ) , . 50 Ca (54.02 w e i g h t p e r c e n t ) , and CI (0.41 w e i g h t p e r c e n t ) . Data was computer r e d u c e d u s i n g Bence-Albee c o r r e c t i o n f a c t o r s (Bence and A l b e e , 1968). F l u o r i n e and c h l o r i n e a n a l y s e s can o n l y be c o n s i d e r e d q u a l i t a t i v e b ecause o f t h e low amounts of t h e s e e l e m e n t s p r e s e n t i n t h e s t a n d a r d s . 4.4 A n a l y t i c a l R e s u l t s 4.4.1 Data T a b u l a t i o n Complete a n a l y t i c a l d a t a f o r a t o m i c a b s o r p t i o n and m i c r o p r o b e a r e t a b u l a t e d i n A p p e n d i x C.3 by form o f m a g n e t i t e ( l o d e o r d i s s e m i n a t e d ) by t y p e o f h o s t r o c k . Summaries of d a t a a r e t a b u l a t e d where needed i n s u c c e e d i n g c h a p t e r s . 4.4.2 A c c u r a c y and P r e c i s i o n o f A n a l y s e s P r e c i s i o n A n a l y t i c a l p r e c i s i o n o f a t o m i c a b s o r p t i o n a n a l y s e s was checked by s p l i t t i n g 16 samples i n t o two and a n a l y s i n g t h e r e p l i c a t e samples i n d e p e n d e n t l y of t h e o r i g i n a l samples (Appendix C.4). A p r e c i s i o n o f 20 p e r c e n t has been t a k e n as t h e maximum a c c e p t a b l e p r e c i s i o n and e l e m e n t s compared a g a i n s t t h i s l e v e l u s i n g t h e method o f Thompson and Howarth (1976). On t h i s b a s i s c o p p e r , magnesium, manganese and vanadium have a p r e c i s i o n b e t t e r t h a n 20 p e r c e n t ; c o b a l t and n i c k e l have a p r e c i s i o n o f about o r s l i g h t l y worse t h a n 20 p e r c e n t ; and chromium, l e a d , t i t a n i u m and z i n c have a p r e c i s i o n s e r i o u s l y worse t h a n 20 p e r c e n t . Poor p r e c i s i o n f o r 51 chromium and l e a d i s caused by s e v e r a l v a l u e s b e i n g below t h e d e t e c t i o n l i m i t o f t h e i n s t r u m e n t . A c c u r a c y o f D a t a A q u a l i t a t i v e assessment o f t h e a c c u r a c y o f a t o m i c a b s o r p t i o n d a t a was g a i n e d by a n a l y s i n g a h e m a t i t e o r e s t a n d a r d (SCH-1; S t e g e r e t a l . , 1975) and a Japanese m a g n e t i t e o r e s t a n d a r d (#810-1) i n q u a d r u p l i c a t e (Appendix C.4). No recommended o r p r o v i s i o n e d v a l u e s a r e g i v e n f o r c o b a l t , n i c k e l , l e a d and z i n c i n e i t h e r s t a n d a r d and i n a d d i t i o n no v a l u e s a r e g i v e n f o r chromium and vanadium i n .st a n d a r d #810-1. Copper and.magnesium v a l u e s a r e t h e most a c c u r a t e b e i n g w i t h i n f i v e p e r c e n t o f v a l u e s g i v e n f o r s t a n d a r d #810-1. Chromium, manganese and t i t a n i u m v a l u e s a r e 30 t o 50 p e r c e n t l o w e r t h a n s t a n d a r d v a l u e s , and manganese i s c o n s i s t e n t l y 40 p e r c e n t l o w e r t h a n s t a n d a r d v a l u e s . P r e c i s i o n f o r t h e l o w amount o f vanadium p r e s e n t i n SCH-1 i s t o o p o o r t o a l l o w an assessment o f a c c u r a c y . P o s s i b l e r e a s o n s f o r low r e a d i n g s a r e d i s c u s s e d i n A p p e n d i x C.4. S t a n d a r d #810-1 was a l s o a n a l y s e d - by e l e c t r o n m i c r o p r o b e ' (Appendix C.4). Use o f a wet c h e m i c a l l y a n a l y s e d s t a n d a r d such as #810-1 as a m i c r o p r o b e s t a n d a r d may have l i t t l e meaning because i n c l u s i o n and i m p u r i t i e s i n c l u d e d i n t h e wet a n a l y s i s a r e e x c l u d e d i n t h e p r o be a n a l y s i s . D e s p i t e t h i s d i f f i c u l t y m i c r o p r o b e r e s u l t s f o r t i t a n i u m , a l u m i n i u m , i r o n and manganese a r e s i m i l a r t o t h o s e r e p o r t e d t o t h e s t a n d a r d . Lower m i c r o p r o b e v a l u e s f o r s i l i c a , magnesium and c a l c i u m i n d i c a t e s t h e s e e l e m e n t s o c c u r m a i n l y as i n c l u s i o n s i n t h e s t a n d a r d . 52 I n g e n e r a l , m i c r o p r o b e and a t o m i c a b s o r p t i o n r e s u l t s a r e i n c l o s e agreement. The w o r s t e x c e p t i o n s a r e magnesium and manganese. M i c r o p r o b e r e s u l t s t e n d t o be l o w e r by a f a c t o r o f 0.1 f o r magnesium and h i g h e r by a f a c t o r o f a p p r o x i m a t e l y 4 f o r manganese. Low magnesium v a l u e s a r e p r o b a b l y caused by t h e element o c c u r r i n g i n d i s c r e t e i n c l u s i o n s . H i g h manganese v a l u e s can be p a r t l y e x p l a i n e d by low a t o m i c a b s o r p t i o n v a l u e s f o r manganese. 4.5 A p p l i c a b i l i t y o f R e s u l t s The;, t h r e e s o u r c e s o f d a t a v a r i a b i l i t y i n t h i s s t u d y : between o u t - • c r o p s , w i t h i n o u t c r o p s (sample v a r i a n c e ) , and between sample r e p l i c a t e s ( a n a l y t i c a l e r r o r ) were i n v e s t i g a t e d u s i n g a n e s t e d a n a l y s i s of v a r i a n c e ( G r i f f i t h s , 1967; d e t a i l s : A p p e n d i x C.5) on d u p l i c a t e and r e p l i c a t e samples (Appendix C . l ) . R e s u l t s o f t h i s i n v e s t i g a t i o n d e t e r m i n e d how r e p r e s e n t a t i v e samples were o f o u t c r o p s and u n i t s b e i n g sampled. From t h i s a n a l y s i s o f v a r i a n c e f o u r main c o n c l u s i o n s c o n c e r n i n g t h e d i s t r i -b u t i o n o f m i n o r elements i n m a g n e t i t e a n a l y s e d h e r e a r e : (1) f o r a l l e l e m e n t s e x c e p t copper and l e a d , v a r i a t i o n between o u t c r o p s i s g r e a t e r t h a n l o c a l v a r i a t i o n w i t h i n o u t c r o p s ( s a m p l i n g e r r o r ) ; (2) f o r c o p p e r and l e a d , s a m p l i n g e r r o r i s g r e a t e r t h a n v a r i a t i o n between o u t c r o p s ; (3) f o r chromium, c o p p e r , magnesium, and manganese, s a m p l i n g e r r o r i s g r e a t e r t h a n a n a l y t i c a l e r r o r ; and (4) f o r c o b a l t , l e a d , n i c k e l , t i t a n i u m , vanadium and z i n c a n a l y t i c a l e r r o r i s g r e a t e r t h a n s a m p l i n g e r r o r . 53 These r e s u l t s Indicate that for a l l elements except copper and lead, sampling and a n a l y t i c a l errors cause s i g n i f i c a n t l y l e s s v a r i a b i l i t y i n data than natural v a r i a b i l i t y of elements within a un i t . Therefore, for these elements sampling of outcrops i s a s t a t i s t i c a l l y v a l i d method of estimating the mean content and variance of minor elements i n magnetite over an e n t i r e u n i t . V a r i a b i l i t y of copper and lead i n magnetite within an outcrop, however, i s s u f f i c i e n t l y greater than v a r i a b i l i t y of these elements over a u n i t , such that sampling of outcrops i s not a v a l i d method of evaluating the minor element content and variance i n magnetite for a un i t . Copper and lead, therefore, w i l l be not used i n char a c t e r i z i n g magnetite from the Iron Mask b a t h o l i t h . 54 CHAPTER 5 MINOR AND MAJOR ELEMENTS IN MAGNETITE  FROM IRON MASK BATHOLITH 5.1 I n t r o d u c t i o n C h a r a c t e r i z a t i o n o f m a g n e t i t e f r o m t h e I r o n Mask b a t h o l i t h , d e s c r i b e d i n t h i s c h a p t e r , w i l l be done b o t h i n terms o f o v e r a l l com-p o s i t i o n based on major and minor o x i d e s d e t e r m i n e d by e l e c t r o n m i c r o p r o b e . and i n terms o f mi n o r element c o n t e n t a l o n g as d e t e r m i n e d by a t o m i c a b s o r p t i o n . F o r c o m p a r a t i v e p u r p o s e s m a g n e t i t e samples have been grouped by f o r m ( d i s s e m i n a t e d o r m a s s i v e ) and h o s t r o c k ( s y e n i t e , d i o r i t e , p i c r i t e ) . The term " s y e n i t e " as used i n t h i s s t u d y i s e q u i v a l e n t t o t h e C h e r r y Creek u n i t ; and d i o r i t e s a r e e q u i v a l e n t t o t h e Pothook and I r o n Mask H y b r i d u n i t s (Chapt. 2.3, F i g . 2.2). Samples were grouped on t h e b a s i s o f p e t r o g r a p h i c a n a l y s i s (Appendix B ) , mapping by N o r t h c o t e ( 1 9 7 7 ) , and e x a m i n a t i o n o f samples by N o r t h c o t e ( p e r s . comm., 1977). As w i t h any a r t i f i c i a l s u b d i v i s i o n , t h i s c l a s s i f i c a t i o n has s h o r t c o m i n g s because o f : (1) t h e wide v a r i e t y o f r o c k t y p e s p r e s e n t i n t h e b a t h o l i t h ; (2) t h e •complex i n t r u s i v e h i s t o r y and g r a d a t i o n a l n a t u r e o f c o n t a c t s ; and (3) t h e u n c e r t a i n age r e l a t i o n s h i p s o f some i n t r u s i v e v a r i e t i e s . D e s p i t e t h e s e p r o b l e m s , a n a l y s i s o f d a t a p r e s e n t e d l a t e r i n t h i s c h a p t e r i n d i c a t e s t h e s u b d i v i s i o n s used h e r e a r e v a l i d and w o r k a b l e . D i s t r i b u t i o n s o f a l l m i n o r e l e m e n t s i n m a g n e t i t e samples d e s c r i b e d i n t h i s c h a p t e r f o l l o w a l o g n o r m a l d i s t r i b u t i o n , t h e r e f o r e , f o r s t a t i s t i c a l p u r p o s e s a l l d a t a has been l o g - t r a n s f o r m e d u n l e s s o t h e r w i s e i n d i c a t e d . 55 F o r l o g - t r a n s f o r m a t i o n s v a l u e s o f 0 ppm have been a r b i t r a r i l y a s s i g n e d v a l u e s o f 0.1 ppm. 5.2 C o m p o s i t i o n o f M a g n e t i t e Samples f r o m I r o n Mask B a t h o l i t h C o m p o s i t i o n s of 13 d i s s e m i n a t e d and m a s s i v e m a g n e t i t e samples were d e t e r m i n e d u s i n g t h e e l e c t r o n m i c r o p r o b e ( S e c t i o n 4.3.2). R e s u l t s of t h e a n a l y s i s a r e g i v e n i n T a b l e 5.1 and p l o t t e d i n F i g s . 5.1 and 5.2. A minimum o f t h r e e m a g n e t i t e g r a i n s p e r sample were a n a l y s e d , however, f o r p u r p o s e s o f d e t e r m i n i n g a v e r a g e c o m p o s i t i o n s o n l y t h o s e a n a l y s e s t o t a l l i n g o v e r 97 p e r c e n t were i n c l u d e d . M o l e c u l a r p e r c e n t u l v o s p i n e l was c a l c u l a t e d based on t h e measured t i t a n i u m c o n t e n t . The low t o t a l o x i d e s f o r m a g n e s i o c h r o m i t e (IM 35) i n T a b l e 5.1 i s a t t r i b u t e d t o poor s u r f a c e p r e p a r a t i o n f o r probe a n a l y s i s : g r a i n s were rounded by t h e p o l i s h i n g p r o c e d u r e . However, c o n c l u s i o n s based on t h e s e a n a l y s e s a r e n o t a f f e c t e d by t h i s low t o t a l . I n s p e c t i o n o f F i g . 5.1 shows t h a t m a g n e s i o c h r o m i t e and chromium r i c h m a g n e t i t e (#15) from p i c r i t e have a c o m p o s i t i o n w h i c h i s d i s t i n c t f r om d i s s e m i n a t e d and m a s s i v e m a g n e t i t e i n s y e n i t e and d i o r i t e . C h r o m i t e s s u c h as i n sample IM 35 a r e t y p i c a l l y a s s o c i a t e d w i t h p i c r i t e s , p e r i d o t i t e s , d u n i t e s and k i m b e r l i t e s ( H a g g e r t y , 1976) whereas t h e com-p o s i t i o n o f chromium r i c h m a g n e t i t e i n sample #15 a p p e a r s t o be s i m i l a r t o c o m p o s i t i o n s r e p o r t e d f o r m a g n e t i t e s i n b a s a l t i c r o c k s ( H a g g e r t y , 1976; T a b l e Hg-20). B o t h d i s s e m i n a t e d and l o d e m a g n e t i t e p l o t i n a TABLE 5.1 ELECTRON MICROPROBE ANALYSES OF MAGNETITES AND CHROMITES FROM IRON MASK BATHOLITH  AND WATCHING CREEK, B.C. ANALYSES ARE THE AVERAGE OF THREE GRAINS PER SAMPLE  UNLESS OTHERWISE STATED. STANDARD ERROR OF THE MEAN (s//n)" IS IN BRACKETS. IB 6B . 8 (2 anal.) 9A 12 15.(2 anaL) IM 16 (2 anaL) sio 2 0.08 (0.04) : 0.14 (0.05) 0.42 (0.22) 0.21 (0.09). 0.09 (0.01) 0.07 (0.01) 0.25 (0.11) T i 0 2 0.23 (0.05) 1.26 (0.70) 0.08 (0.03) 0.06 (0.03) 1.71 (0.43) . 1.81 (0.29) 0.98 (0.69) A 1 2 ° 3 0.80 (0.43) 0.59 (0.26) 0.58 (0.10) 0.27 (0.14) 1.96 (0.91) 7.49 (0.44) 0.35 (0.06) Cr 203 0.01 (0.01) 0.08 (0.05) 0.02 (0.01) 0.02 (0.01) 0.04 (0.01) 7.02. (2.15) 0.03 (0.01) V2°3 ':. 1.60 (0.09) 1.59 (0.05) 0.98 (0.03) 0.99 (0.04) 1.38 (0.05) 0.26 (0.04) 1.71 (0.02) F eO 91.72 (0.27) 87.39 (1.31) 88.06 (0.59) 92.07 (0.81) 86.00 (1.15) 67.05 (1.28) 89.77 (0.15) MnO 0.14 (0.10) 0.37 (0.15) 0.18 (0.02) 0.07 (0.02) 0.58 (0.13) 0.29 (0.01) 0.23 (0.07) MgO 0.08 (0.07) 0.05 (0.02) 0.61 (0.11) 0.01 (0.00) 0.12 (0.09) 8.85 (0.25) 0.42 (0.20) CaO 0.01 (0.01) 0.01 (0.01) 0.08 (0.07) "0.04 (0.02) 0.06 (0.06) 0.04 (0.03) 0.00 (0.00) Sura 94.67 91.48 90.99 93.75 91.89 92.87 93.73 Recalculated analyses (see text) FeO '32.57 (0.44) 32.17 (0.53) 30.38 (0.09) 31.91 (0.37) 33.06 (0.76) 25.51 (0.46) 32.27 (0.48) F e 2 ° 3 65.75 (0.53) 61.38 (2.04) 64.11 (0.76) 66.86 (0.67) 58.84 (2.08) 46.18 (1.93) 63.90 (0.37) Total 101.27 97.64 97.42 100.45 97.79 97.52 100.14 Mole. / Usp. 0.97 (0.28) 4.27 (1.98) 1.86 (0.93) 1.00 (0.28) 5.30 (1.23) 5.00 (0.75) 3.73 (1.54) NOTES: Samples IB and 12 are disseminated magnetite i n Pothook d i o r i t e ; sample 6B Is disseminated magnetite i n Cherry Creek syenite; samples 8 and 9A are massive magnetite i n Fothook d i o r i t e ; sample 15 i s disseminated magnetite i n p i c r i t e ; sample IM 16 i s a massive magnetite fragment i n Cherry Creek monzonite. Sample locations are shown on Figs. 2.2, 2.3a and 2.3b. TABLE 5.1 (continued) 1M 16B (2 anal.) 1M 21-7 (2 anaL) 1M 25 1M 27A (1 anal.) 1M 30 1M 35 0.13 (0.00) 0.65 (0.39) . 0.03 (0.02) 0.15 1.01 (0.43) 0.18 (0.18) 3.37 (0.18) 0.03 (0.01) 0.12 (0.02) 0.03 2.09 (0.28) 0.39 (0.13) 0^03 (0.00) 0.41 (0.09) 0.00 (0.00) 0.16 1.80 (0.29) 7.37 (1.34) 0.06 (0.0A) 0.00 (0.00) 0.10 (0.04) 0.01 0.01 (0.00) 36.53 (5.54) 1.61 (0.18) 1.09 (0.12) 1.67 (0.02) 1.28 1.14 (OvlO) 0.05 (0.03) 88.16 (2.39) 88.74 (0.61) 91.43 (0.50) 87.03 86.02 (0.32) 35.34 (3.63) 0.25 (0.15) •0.07 (0.00) 0.05 (0.00) 0.03 0.61 (0.15) 0.38 (0.04) 0.05 (0.01) 0.37 (0.11) 0.00 (0.00) 0.38 0.20 (0.15) 11.98 (0.22) 0.0A (0.03) 0.16 (0.04) 0.00 (0.00) 2.55 0.01 (0.00) 0.04 (0.01) 93.68 91.51 93.41 91.62 92.90 92.28 S i 0 2 T i 02  A 1 2 ° 3 C r 2 ° 3 v 2 o 3 FeO MnO MgO CaO Sum Recalculated analyses (see text) FeO 34.47 (0.57) 31.11 (0.31) 31.77 (0.09) 27.61 34.56 (0.36) 13.29 (0.46) F e ^ 59.67 (2.02) 64.05 (1.02) 66.31 (0.45) 66.04 57.19 (0.66) 24.55 (3.59) Total 99.68 97.94 100.05 98.24 98.62 94.76 Mole. % Usp. 10.26 (0.74) 2.60 (1.47) 0.49 (0.16) 0.67- 9.89 (2.53) — . NOTES: Sample IM 16B i s disseminated magnetite i n Cherry Creek monzodiorite; sample IM 21-7 i s massive magnetite i n Pothook d i o r i t e ; samples IM 25 and IM 27A are disseminated magnetite i n Cherry Creek syenitejsample IM 30 i s a magnetite veinlet cutting Pothook d i o r i t e ; sample IM 35 i9 disseminated magnetite i n p i c r i t e . Sample locations are shown on Figs. 2.1, 2.2, 2.3a and 2.3b. 58 S Y M B O L S F i g . 5 . 1 . C o m p o s i t i o n o f m a g n e t i t e f r o m I r o n M a s k b a t h o l i t h . C o m p o s i t i o n f i e l d s f o r b a s a l t s ( B I ) , b a s a n i t e s ( B s ) , s a l i c v o l c a n i c s ( S I ) , a n d c a r b o n a t i t e s ( C b ) a r e s h o w n a s i n P r i n s ( 1 9 7 2 ) . N o t e t h e a n o m a l o u s p i c r i t e c o m p o s i t i o n s . 59 S Y M B O L S D I S S E M I N A T E D 0 M a g n e t i t e Fe^Og Hematite g. 5.2. C o m p o s i t i o n o f m a g n e t i t e from I r o n Mask b a t h o l i t h i n terms o f major end components. M a j o r s o l i d s o l -u t i o n s e r i e s a r e shown by t i e l i n e s . C h r o m i t e and chromium r i c h m a g n e t i t e from p i c r i t e a r e not i n c l -uded . 60 compact group n e a r t h e i d e a l s t o i c h r o m e t r i c f o r m u l a o f m a g n e t i t e ( F i g . 5.2). Low amounts o f minor e l e m e n t s i n m a g n e t i t e a r e thought t o i n d i c a t e m a g n e t i t e f o r m a t i o n a t t e m p e r a t u r e s r e l a t i v e l y l ow f o r i g n e o u s r o c k s s u c h as f o r c a r b o n a t i t e s and p e g m a t i t e s ( L i s t e r , 1966; P r i n s , 1972). The c o m p o s i t i o n a l f i e l d shown i n F i g . 5.1 f o r m a g n e t i t e s i n t h i s s t u d y i s l a r g e l y c o i n c i d e n t w i t h t h e c o m p o s i t i o n a l f i e l d f o r m a g n e t i t e from c a r b o n a t i t e ( P r i n s , 1972), perhaps i n d i c a t i n g s i m i l a r t e m p e r a t u r e s d u r i n g f o r m a t i o n . M a g n e t i t e from o t h e r i g n e o u s r o c k s g e n e r a l l y has a g r e a t e r t i t a n i u m c o n t e n t ( F i g . 5.1). M i c r o p r o b e a n a l y s e s ( e x c l u d i n g p i c r i t e s ) a r e p l o t t e d i n F i g . 5.3 on t h e b a s i s o f FeO-Fe^O^-(^20^+1102)• These a n a l y s e s appear t o form a d i s t i n c t l i n e , :which, assuming d i o r i t e s were formed e a r l i e r t h a n s y e n i t e s , t r e n d s away f r o m C^O^ + T i C ^ and FeO to w a r d Fe^O^. D i s s e m i n a t e d m a g n e t i t e i n d i o r i t e and s y e n i t e , and m a s s i v e m a g n e t i t e form o v e r l a p p i n g f i e l d s a l o n g t h i s t r e n d , however, t h e t r e n d a p p e a r s t o go from d i s s e m i n a t e d m a g n e t i t e i n d i o r i t e t o d i s s e m i n a t e d m a g n e t i t e i n s y e n i t e and f i n a l l y t o m a s s i v e m a g n e t i t e . T h i s t e n d e n c y away from Ti02 + Cr^O^ toward Fe^O^ s u g g e s t s i n c r e a s i n g o x i d a t i o n and d e c r e a s i n g t e m p e r a t u r e d u r i n g m a g n e t i t e f o r m a t i o n i n ' g o i n g f r o m d i o r i t e t o s y e n t i t e and m a s s i v e m a g n e t i t e . 5.3 C o m p o s i t i o n o f A p a t i t e i n M a g n e t i t e Lodes S i x a n a l y s e s o f a p a t i t e i n m a s s i v e m a g n e t i t e from t h e G l e n I r o n mine i n t h e C h e r r y Creek p l u t o n (sample IM 31; F i g . 2.1) were done by e l e c t r o n m i c r o p r o b e . Complete a n a l y s e s a r e g i v e n i n A p p e n d i x C. C o m p o s i t i o n o f a p a t i t e i s e x t r e m e l y u n i f o r m between c r y s t a l s and no z o n i n g i s a p p a r e n t F i g . 5.3. C o m p o s i t i o n o f m a g n e t i t e from I r o n Mask b a t h o l i t h i n terms of FeO-Fe 20 - T i 0 2 + C r ? 0 ^ . Assumed d i f f e r -e n t i a t i o n t r e n d i s o u t l i n e d . 1 -l 62 i n an i n d i v i d u a l c r y s t a l i n a n a l y t i c a l t r a v e r s e s from c e n t r e t o edge. The a v e r a g e a p a t i t e c o m p o s i t i o n based on s i x a n a l y s e s i s g i v e n i n T a b l e 5.2. F l u o r i n e and c h l o r i n e a r e o n l y q u a l i t a t i v e a n a l y s e s because o f poor a n a l y t i c a l p r e c i s i o n due t o t h e low c o n t e n t o f f l u o r i n e and c h l o r i n e i n m i c r o p r o b e s t a n d a r d s ( S e c t i o n 4.3.2). TABLE 5.2 AVERAGE COMPOSITION OF APATITE (SAMPLE 1M31) IN GLEN IRON MAGNETITE LODE, IRON MASK BATHOLITH, B.C. ELEMENT OR OXIDE* WEIGHT % S 1 F~ 2.19 0.39 MgO 0.04 0.004 P 2 0 5 40.83 0.36 CI 0.83 0.33 CaO 55.47 1.41 MnO 0.10 0.01 FeO 0.13 0.009 TOTAL 99.59 1: S i s t h e s t a n d a r d d e v i a t i o n based on s i x a n a l y s e s F l u o r i n e - r i c h a p a t i t e , s u c h as i n sample IM 31, i s t y p i c a l o f a p a t i t e i n t h e magmatic K i r u n a i r o n o r e s ( F r i e t s c h , 1978). 5.4 M i n o r Element C h a r a c t e r i s t i c s o f M a g n e t i t e from I r o n Mask B a t h o l i t h M i c r o p r o b e a n a l y s e s o f m a g n e t i t e d i s c u s s e d i n S e c t i o n 5.2 show t h a t a l l m a g n e t i t e v a r i e t i e s , e x c e p t d i s s e m i n a t e d m a g n e t i t e i n p i c r i t e , have a 63 s i m i l a r c o m p o s i t i o n i n terms o f major o x i d e s . M i n o r e l e m e n t s d e t e r m i n e d by a t o m i c a b s o r p t i o n w i l l be used i n t h i s s e c t i o n t o i n d i c a t e f u r t h e r s i m i l a r i t i e s and d i f f e r e n c e s between m a g n e t i t e o c c u r r i n g as d i s s e m i n a t i o n s and l o d e s i n d i o r i t e and s y e n i t e . S i m i l a r i t i e s , i n m i n o r element p o p u l a t i o n s between m a s s i v e and d i s s e m i n a t e d m a g n e t i t e w o u l d s u p p o r t a g e n e t i c r e l a t i o n between t h e two t y p e s , and i n d i c a t e a p o s s i b l e o r i g i n f o r t h e m a g n e t i t e l o d e s . 5.5.1 D i s s e m i n a t e d m a g n e t i t e Mean m i n o r element abundances i n d i s s e m i n a t e d m a g n e t i t e f r o m s y e n i t e , d i o r i t e , s y e n i t e p l u s d i o r i t e and p i c r i t e a r e t a b u l a t e d i n T a b l e 5.3. T a b l e 5.3A c o n t a i n s a r i t h m e t i c means and s t a n d a r d , d e v i a t i o n s o f l o g a r i t h m s o f d a t a i n A p p e n d i x C. T a b l e 5.3B c o n t a i n s g e o m e t r i c means ( a n t i l o g a r i t h m s o f means g i v e n i n T a b l e 5.3A), and a n t i l o g a r i t h m s o f X±S from T a b l e 5.3B. The r e s u l t i s an asymmetric d i s t r i b u t i o n o f s t a n d a r d d e v i a t i o n s about t h e g e o m e t r i c means. These d a t a w i l l be used i n f o l l o w i n g s e c t i o n s f o r s t a t i s t i c a l c o m p a r i s o n w i t h m i n o r e l e m e n t s i n o t h e r m a g n e t i t e . Note t h a t copper and l e a d a r e n o t i n c l u d e d i n t h e t a b l e due t o poor a n a l y t i c a l o r s a m p l i n g p r e c i s i o n ( S e c t i o n 4.5). W i t h t h e e x c e p t i o n o f t i t a n i u m , minor elements f o u n d i n t h i s s t u d y a r e t y p i c a l o f t h o s e r e p o r t e d f o r i n t e r m e d i a t e r o c k s ( F r i e t s c h , 1970). T i t a n i u m i s l o w e r t h a n n o r m a l l y r e p o r t e d f o r comparable r o c k s , but s i m i l a r amounts have been r e p o r t e d i n m a g n e t i t e from g r a n i t e and g r a n i t i c p e g m a t i t e ( B u d d i n g t o n and L i n d s l e y , 1964). 6 4 TABLE 5 . 3 A SUMMARY OF LOGARITHMIC DATA (PPM) FOR MINOR ELEMENTS IN DISSEMINATED MAGNETITE, IKON MASK BATHOLITH (Numbers a r e l o g a r i t h m i c v a l u e s of l o g - t r a n s f o r m e d d a t a . ) HOST ROCK ~ ~ ELEMENT P A R A -METER 1 CO F F Mg Mn H i T l 2 V Z r T SYENITE n 8 8 8 8 8 7 8 6 X 1 . 6 0 3 2 . 1 1 9 3 . 8 3 1 2 . 8 0 6 2 . 0 2 4 3 . 2 6 7 3 . 5 7 3 1 . 6 2 6 S 0 . 2 1 2 0 . 6 1 6 0 . 2 2 0 0 . 2 2 3 0 . 2 5 9 0 . 3 0 8 0 . 1 4 4 0 . 3 7 7 S/TrT 0 . 0 7 5 0 . 2 1 8 0 . 0 7 8 0 . 0 7 9 0 . 0 9 1 0 . 1 1 6 0 . 0 5 1 0 . 1 3 3 DIORITE n X S S/fn SYENITE p l u s n 15 15 15 15 15 12 15 15 DIORITE X 1 . 6 8 6 2 . 1 0 7 3 . 7 9 9 2 . 8 5 9 1 . 9 7 1 3 . 3 5 6 3 . 5 8 8 1 . 6 4 2 S 0 . 1 7 9 0 . 4 8 1 0 . 2 1 6 0 . 2 2 3 0 . 2 0 7 0 . 2 8 9 0 . 1 1 3 0 . 3 0 6 S//7T 0 . 0 4 6 0 . 1 2 4 0 . 0 5 6 0 . 0 5 8 0 . 0 5 4 0 . 0 8 3 0 . 0 2 9 0 . 0 7 9 P I C R I T E n 6 6 6 6 6 6 6 6 X 2 . 0 0 0 4 . 3 9 5 4 . 7 4 3 3 . 2 3 1 3 . 1 2 7 3 . 1 8 9 3 . 0 4 0 2 . 4 6 2 S 0 . 1 2 3 0 . 2 9 8 0 . 1 3 9 0 . 1 6 6 0 . 2 0 3 0 . 2 7 8 0 . 1 0 6 0 . 0 9 3 0 . 0 5 0 0 . 1 2 2 0 . 0 5 7 0 . 0 6 8 0 . 0 8 3 0 . 1 1 3 0 . 0 4 3 0 . 0 3 8 1 . 7 8 0 2 . 0 9 3 3 . 7 6 3 2 . 9 2 1 1 . 9 1 0 3 . 4 8 0 3 . 6 0 4 1 . 6 6 1 0 . 0 5 5 0 . 3 0 9 0 . 2 2 3 0 . 2 2 3 0 . 1 1 8 0 . 2 3 3 0 . 0 7 2 0 . 2 2 7 0 . 0 2 1 0 . 1 1 7 0 . 0 8 4 0 . 0 8 4 0 . 0 4 5 0 . 1 0 4 0 . 0 2 7 0 . 0 8 6 X • a r i t h m e t i c m e a n ; s • s t a n d a r d e l e v i a t i o n ; %lf~n • s t a n d a r d e r r o r o f t h e m e a n ; n • number o f a n a l y s e s . S a m p l e IM 23 i s n o t i n c l u d e d i n S Y E N I T E ; s a m p l e s 6 5 a n d A l l a r e n o t i n c l u d e d 1n DIORITE b e c a u s e of a n o m a l o u s l y h i g h t i t a n i u m v a l u e s . 65 TABLE 5 . 3 B SUMMARY OF DATA (PPM) FOR MINOR ELEMENTS IN DISSEMINATED MAGNETITE ( N u m b e r s a r e a n t i l o g a r i t h i n s o f l o g - t r a n s f o r m e d i n T a b l e 5 . 3 A ) ELEMENT PARA-HOST ROCK METER 1 Co C r Mg Mn JTi TT2 V In SYENITE n 8 8 8 8 8 7 8 8 * 9 40 132 6 8 0 0 600 106 1850 3 7 4 0 4 2 x g + s 6 5 543 11200 1100 192 3760 5 2 1 0 101 X g - S 25 32 4100 400 58 9 1 0 2 6 9 0 18 DIORITE n 7 7 7 7 7 5 7 7 xg 6 0 124 5 8 0 0 8 0 0 81 3 0 2 0 4 0 2 0 46 X g * * 68 252 9700 1400 107 5160 4 7 4 0 77 X g - 5 53 61 3 5 0 0 5 0 0 62 1770 3 4 0 0 27 SYENITE p l u s n 15 15 15 15 15 12 15 15 DIORITE Xg 49 128 6 3 0 0 700 94 2270 3870 44 X g * * 73 387 10400 1200 151 4420 5 0 2 0 8 9 X g - s 32 42 3 8 0 0 4 0 0 58 1170 2 9 9 0 22 P I C R I T E n 6 6 6 6 6 6 6 6 xg 100 2 . 4 8 5 5 5 3 0 0 1700 1340 1545 1100 290 x g + s 133 4 . 9 3 % 76200 2500 2140 2930 1400 3 6 0 X g - s 75 1 . 2 5 % 4 0 2 0 0 1200 8 4 0 815 8 6 0 2 3 0 1 : n « number o f a n a l y s e s ; Xg • g e o m e t r i c m e a n ; s • s t a n d a r d d e v i a t i o n . 2 : S a m p l e IM 23 i s n o t i n c l u d e d i n S Y E N I T E ; s a m p l e s 4 5 and i l l a r e n o t i n c l u d e d i n DIORITE b e c a u s e o f a n o m a l o u s l y h i g h t i t a n i u m v a l u e s . 6 6 5.4.2 M a s s i v e M a g n e t i t e Mean mi n o r element abundances i n m a s s i v e m a g n e t i t e from f o u r showings a r e t a b u l a t e d i n T a b l e 5.4 based on a l o g t r a n s f o r m a t i o n o f d a t a i n A p p e n d i x C as d e s c r i b e d above f o r T a b l e 5.3. V a r i a t i o n i n m i n o r element c o n t e n t a c r o s s t h e w i d t h o f a l o d e i n two l o c a t i o n s ( F i g . 2.3a and b) i s shown d i a g r a m a t i c a l l y i n F i g s . 5.4 and 5.5. Z i n c , n i c k e l and vanadium abundances show no s y s t e m a t i c p a t t e r n i n e i t h e r c r o s s - s e c t i o n . S m a l l v a r i a t i o n s i n a n a l y t i c a l r e s u l t s f o r vanadium a r e p r o b a b l y caused by random a n a l y t i c a l e r r o r s . Magnesium c o n t e n t i s e r r a t i c a l l y d i s t r i b u t e d i n b o t h c r o s s - s e c t i o n s . C o b a l t a p p e a r s t o d e c r e a s e i n abundance toward t h e c e n t r e o f t h e l o d e i n b o t h c r o s s - s e c t i o n s . T i t a n i u m v a l u e s a r e e e r r a t i c i n c r o s s - s e c t i o n IM 21; b u t i n c r o s s - s e c t i o n IM .22 t i t a n i u m shows a l a r g e c e n t r a l h i g h , f l a n k e d by lows and much s m a l l e r , s e c o n d a r y h i g h s a t t h e l o d e m a r g i n s . Chromium shows a s h a r p , c e n t r a l peak i n s e c t i o n IM 21, and a broad' asymmetric h i g h i n s e c t i o n IM 22. These minor element d i s t r i b u t i o n s a c r o s s t h e l o d e s appear t o be ambiguous as f a r as g e n e s i s o f m a g n e t i t e l o d e s i s c o n c e r n e d . F o r magmatic i n j e c t i o n d e p o s i t s a smooth s y m m e t r i c a l v a r i a t i o n , s u c h as f o u n d w i t h c o b a l t i n F i g . 5.4, would be e x p e c t e d , r e f l e c t i n g c o o l i n g o f t h e m a g n e t i t e "magma" from t h e m a r g i n s i n w a r d - F o r h y d r o t h e r m a l v e i n d e p o s i t s a h i g h l y v a r i a b l e z o n a t i o n , s u c h as shown by magnesium i n F i g . 5.5 w o u l d p r o b a b l y be e x p e c t e d , due t o v a r i a t i o n s i n t e m p e r a t u r e , p r e s s u r e an c o m p o s i t i o n o f t h e h y d r o t h e r m a l f l u i d d u r i n g d e p o s i t i o n o f m a g n e t i t e . 6 7 TABLE 5.4A SUMMARY OF LOGARITHMIC DATA FOR MINOR ELEMEMTS IN MASSIVE MAGNETITE ( N u m b e r s a r e l o g a r i t h m i c v a l u e s of l o g - t r a n s f o r i n e d d a t a ) i HOST PARA-ELEMENT \ PROPERTY ROCK METER 1 Co C r Mg Mn N i T i * V Zn MAGNET DIORITE n 31 31 31 31 31 31 31 31 T 1.867 0.104 3.824 2.589 2.135 2.588 3.484 1.409 S 0.122 0.847 0.119 0.106 0.084 0.197 0.052 0.118 S/Tn 0.022 0.152 0.021 0.019 0.015 0.035 0.009 0.021 IRON CAP DIORITE n 2 2 2 2 2 2 2 2 J 2.129 1.595 3.517 3.225 2.055 . 3.611 3.505 1.805 S 0.107 0.553 0.220 -0.007 0.078 0.015 0.075 0.091 S / / n 0.076 0.391 0.156 0.005 0.055 0.011 0.053 0.064 MAGNET DIORITE n 33 33 33 33 33 33 33 33 p l u s I 1.883 0.165 3.806 2.637 2.131 2.650 3.485 1.433 IRON CAP S 0.135 0.924 0.143 0.183 0.085 0.313 0.052 0.150 S/Vrr 0.024 0.161 0.025 0.032 0.015 0.055 0.009 0.026 AFTON SYENITE n 4 4 4 i 4 4 4 4 4 x" 2.019 0.150 3.882 3.018 2.182 2.516 3.284 2.113 S 0.323 0.859 0.200 0.355 0.188 0.461 0.230 0.490 s / , p r 0.162 0.430 0.100 0.178 0.094 0.231 0.115 0 . 2 4 5 GLEN SYENITE n 1 1 1 1 1 1 1 1 IRON Y S S/TfT 1.770 - 1 . 0 0 . 3.531 2.531 1.813 2.407 3.380 1.279 AFTON SYENITE n 5 .5 5 5 5 5 5 5 p l u s GLEN IRON I S 1.970 10.301 - 0 . 0 8 0 0.905 3.812 0.234 2.921 0.377 2.109 0.232 2.494 0.402 3.303 0.204 1.946 0 . 5 6 5 S / f i T 0.135 0.405 0.105 0.169 0.104 0.180 0.091 0 . 2 5 3 ALL OF DIORITE n 38 38 38 38 38 38 38 38 ABOVE and 7 1.894 0.138 3.807 2.674 2.128 2.630 3.461 1.500 SYENITE S 0.163 0.913 0.153 . 0.232 0.110 0.324 0.104 0.292 S/fn 0.026 0.148 0.025 0.038 0.018 0 . 0 5 3 0.017 0.047 1: n • number o f a n a l y s e s ; X * a r i t h m e t i c m e a n ; s » s t a n d a r d d e v i a t i o n ; ; s / n = s t a n d a r d e r r o r of t h e m e a n . 6 8 TABLE 5 . 4 B SUMMARY OF DATA FOR MINOR ELEMENTS IN MASSIVE MAGNETITE ( N u m b e r s a r e a n t i l o g a r i t h m s of l o g - t r a n s f o r m e d d a t a i n T a b l e 5 . 4 A ) _ • . . E L £ H £ | | T HOST PARA-PROPERTY ROCK METER 1 Co C r Mg Mn H i T i ' V Z n MAGNET DIORITE n 31 31 31 31 31 31 31 31 Xg 74 1 6700 4 0 0 136 387 3 0 5 0 26 xg+s . 9 8 9 . 8 8 0 0 5 0 0 166 610 3 4 4 0 34 X g - S 56 0 5100 3 0 0 112 246 2700 20 IRON CAP DIORITE n 2 " 2 2 2 2 2 2 2 X g 135 39 3 3 0 0 1700 114 4 0 8 0 3 2 0 0 64 Xg+S 172 141 5500 1700 136 4 2 3 0 3 8 0 0 79 X g - S 105 11 2 0 0 0 1700 95 3 9 4 0 2 6 9 0 5 2 MAGNET DIORITE n 33 33 33 33 33 33 33 33 p l u s Xg 76 1 6 4 0 0 400 135 450 3050 27 IRON CAP Xg + S 104 12 8 9 0 0 700 164 9 2 0 3 4 4 0 38 X g - S 56 0 4 6 0 0 3 0 0 U l 220 2710 19 AFTON SYENITE n 4 4 4 4 4 4 4 4 Xg 104 1 7600 1000 152 328 1920 130 Xg + S 220 10 12100 2400 234 9 4 8 3270 401 X g - S 50 0 4 8 0 0 5 0 0 99 114 1130 42 GLEN SYENITE n 1 1 1 1 1 1 1 1 IRON Xg Xg+S X g - S 59 0 3 4 0 0 300 65 255 2 4 0 0 19 AFTON SYENITE n 5 5 5 5 5 5 5 5 p l u s GLEN IRON Xg Xg+S 93 187 1 7 6 5 0 0 11100 8 0 0 2 0 0 0 129 220 312 787 2010 3210 88 324 X g - S 47 0 3 8 0 0 3 0 0 75 124 1260 24 ALL OF DIORITE n 38 38 38 38 38 38 38 38 ABOVE and Xg 78 1 6 4 0 0 500 134 427 2890 32 SYENITE Xg+S 114 11 9100 8 0 0 173 9 0 0 3670 6 2 X g - S 54 0 4500 300 104 202 2 2 8 0 16 1 : n • number o f a n a l y s e s ; Xg « g e o m e t r i c m e a n ; s • s t a n d a r d d e v i a t i o n . 6 9 150 100 Q. 0_ 50 0 / v Ni Co Zn J L J I I I J L 2 3 4 5 6 7 8 9 1 0 CHJP SAMPLE NUMBER SAMPLE IM 21-0 to II II 150 100 Q. a. 50 Ni .7 • - a — a — K Co •A 'A A J I I L _ l L Zn 4 J i _ (B) SAMPLE IM 22-0 to 10 2 3 4 5 6 7 8 9 CHIP SAMPLE NUMBER 10 F i g . 5 . 4 . V a r i a t i o n i n C o , N i , a n d Z n a b u n d a n c e a c r o s s t h e M a g n e t m a g n e t i t e l o d e , I r o n M a s k b a t h o l i t h , B.C. L o c a t i o n o f c r o s s - s e c t i o n s i s s h o w n o n F i g . 2.3A, 70 8or 60 Q-40 CL 20 k \ Ti C r - / v ; — - " ^ I I 5 l _ \ • — 0 . — SAMPLE IM 21-0 to 2 3 4 5 6 7 8 CHIP SAMPLE NUMBER 80 k 60 2 4 0 CL a. 20 Ti o« o r b- 4 ~ + - - % + *. 1 / \ /A Mg / V - - " — a — . - a — . — * (B) SAMPLE IM22 - O t o 10 2 3 4 5 6 7 8 9 CHIP SAMPLE NUMBER 10 F i g . 5 . 5 . V a r i a t i o n i n C r , M g ( X 1 0 3 ) , T i ( X l O ) , a n d V ( X 1 0 2 ) a b u n d a n c e a c r o s s t h e M a g n e t m a g n e t i t e l o d e , I r o n M a s k b a t h o l i t h , B.C. L o c a t i o n o f c r o s s - s e c t i o n s i s s h o w n o n F i g . 2.3A.. 71 5.5 A n a l y s i s o f M i n o r Element D i s t r i b u t i o n s 5.5.1 Comparison, o f Means and V a r i a n c e s A s t a t i s t i c a l c o m p a r i s o n o f means and v a r i a n c e s t a b u l a t e d i n T a b l e s 5.3 and 5.4 was c a r r i e d out t o d e t e r m i n e c o m p o s i t i o n a l d i f f e r e n c e s and s i m i l a r i t i e s between v a r i o u s m a g n e t i t e groups. V a r i a n c e s were compared u s i n g an F t e s t ( e . g . D i x o n and Massey, 1969). The t j t e s t :used torcompare t h e means depended on t h e r e s u l t s o f t h e F t e s t . I f v a r i a n c e s o f t h e element b e i n g t e s t e d were s t a t i s t i c a l l y t he same; a s t a n d a r d t ' : t e s t ( D i x o n and Massey, i b i d . , p. 114) was used. However, i f t h e v a r i a n c e s were s i g n i f i c a n t l y d i f f e r e n t a m o d i f i e d t t e s t as d e s c r i b e d i n D i x o n and Massey ( i b i d . , p. 119) was used. A c o m p a r i s o n o f mi n o r e l e m e n t s i n d i s s e m i n a t e d m a g n e t i t e was made between s y e n i t e - and d i o r i t e - h o s t e d groups and between s y e n i t e - p l u s d i o r i t e h o s t e d and p i c r i t e - h o s t e d groups. C a l c u l a t e d F and t v a l u e s , c r i t i c a l F and t v a l u e s a t t h e 99 p e r c e n t c o n f i d e n c e l e v e l and d e g r e e s o f freedom, and t a b u l a t e d i n T a b l e 5.5. R e s u l t s o f t h e t e s t s a r e summarized i n T a b l e 5.6. A l l v a r i a n c e s f o r mi n o r e l e m e n t s i n s y e n i t e -h o s t e d d i s s e m i n a t e d m a g n e t i t e a r e s t a t i s t i c a l l y t h e same as t h o s e f o r minor e l e m e n t s i n d i o r i t e - h o s t e d d i s s e m i n a t e d m a g n e t i t e , w i t h the e x c e p t i o n o f c o b a l t . Means f o r mi n o r e l e m e n t s i n t h e same two groups a r e a l l s t a t i s t i c a l l y t h e same. I n c o n t r a s t t o t h e s e s i m i l a r i t i e s , c o m p a r i s o n o f mi n o r e l e m e n t s i n s y e n i t e ^ a n d d i o r i t e h o s t e d d i s s e m i n a t e d m a g n e t i t e t o t h o s e i n p i c r i t e h o s t e d d i s s e m i n a t e d m a g n e t i t e show s i g n i f i c a n t d i f f e r e n c e s i n means. A l t h o u g h v a r i a n c e s o f a l l e l e m e n t s TABLE 5 . 5 C a l c u l a t e d F and t values w i t h comparable c r i t i c a l  v a l u e s at 99 percent c o n f i d e n c e l e v e r f o r v a r i o u s magnetite groups, i r o n mask b a t h o l i t h , B . C . MAGNETITE FORM (DEPOSIT) ELEMENT HOST PARA-ROCK METER2 Co Cr Mg Mn Ni T1 V Zn . . DIORITE ^ m a g n e t * 2 ^ 1 . 6 2 3 - - 1 . 5 9 0 - - 0 . 4 1 4 - - 1 . 6 1 3 - - 1 . 9 6 7 - - 2 . 1 9 4 - 3 . 3 8 0 - 1.173 2.111 1.798 0.062 -1 .189 2.303 2.982 3.588 1.645 . DIORITE SYENITE F 4.97 1.04 2.68 4.24 7.45 1.65 15.4 14.2 F c r i f 4 .00 13.8 4 . 0 0 4.00 4.00 4.00 4.00 4 . 0 0 SYENITE t - 0 . 6 4 0.55 - 0 . 0 8 - 1 . 6 6 0.21 1.00 1.99 - 2 . 0 2 t c r i t * 2.90 2.72 2.72 2.90 2.90 2.72 2.92 2 . 9 2 d . f . 17 36 36 17 17 36 16 16 SYENITE F 14.86 3.97 1.03 1.00 4.82 1.75 4.00 2.76 DIORITE F c r 1 t « 8.26 8.26 7.19 8.26 8.26 15.21 8.26 8.26 t - 2 . 2 8 0.10 0 . 5 9 1.00 1.07 - 1 . 3 0 - 0 . 5 1 - 0 . 2 1 t e n t * 2.67 3.01 3.01 3.01 3.01 3.17 3.01 3.01 d . f . 56 13 13 13 13 10 13 13 SYENITE F 2.12 2.68 2.41 1.80 1.04 1.08 1.14' 10.83 DIORITE F c r 1 f 9.78 9.78 9.78 9.78 9.78 9.96 9.78 9.78 t - 3 . 9 1 -10.76 - 9 . 8 4 - 3 . 6 8 17.77 1.17 10.2 - 9 . 3 5 PICRITE t c r i t * 2.86 2.86 2.86 2.80 2.86 2.92 2.86 2 . 5 8 d . f . 19 19 19 19 19 16 19 209 MASSIVE (MAGNET) A) v e r s u s B) versus MASSIVE (AFTONT DISSEMINATED C) DISSEMINATED" v e r s u s DISSEMINATED D) versus DISSEMINATED 1: I n t e r p r e t a t i o n of F and t t e s t s i s i n T a b l e 5 . 6 . 2 . F = F v a l u e c a l c u l a t e d from data i n Tables 5 . 3 and 5 . 4 ; F c r i t . = c r i t i c a l F value at the 99 percent c o n f i d e n c e l e v e l ; t = t value c a l c u l a t e d from data i n Tables 5 . 3 and 5 . 4 ; ^ c r i t = c r i t i c a l 1 value at the 99 percent c o n f i d e n c e l e v e l ; d i f . = degrees of freedom. 3 . Because IRON CAP d e p o s i t c o n t a i n e d o n l y 2 values f o r each element, v e r s u s 31 f o r MAGNET d e p o s i t , t h e n u l l h y p o t h e s i s was t e s t e d by s e e i n g i f X i r o n c a p w a s w i t h i n 2 standard d e v i a t i o n s of X m a g n e t * TABLE 5 . 5 c o n t . MAGNETITE HOST FORM (DEPOSIT) ROCK ELEMENT PARA-o METER2 Co Cr Mg Mn Ni T i V Zn MASSIVE (MAGNET) DIORITE E l versus DISSEMINATED DIORITE F F c r i t -t t c r i f d . f . 4 . 9 2 7.23 - 1 . 8 2 2.73 36 7.51 7.23 10.37 2.58 235 3.51 • 3.47 - 0 . 7 0 2.70 41 4 . 4 3 3.47 3.73 2.70 40 1.97 3.47 - 5 . 9 5 2.73 36 1.40 4.02 9.25 2.72 36 1.92 3.47 4 . 9 4 2.73 36 3.70 3.47 2.85 2.70 41 MASSIVE (MAGNET) DIORITE F) v e r s u s DISSEMINATED SYENITE F F c r i t * t c a l c * t e n t * d . f . 3 . 0 2 3.30 - 4 . 6 4 2.72 37 1.89 5.99 6.29 2.72 37 3.42 3.30 0.09 2.67 57 4.43 3.30 2.55 2.67 55 9.51 3.30 - 1 . 2 0 2.68 52 2.44 3.47 7.39 2.72 36 7.67 3 . 3 0 1.72 2 . 6 8 52 .. 10.21 3 . 3 0 1.61 2.68 52 MASSIVE (MAGNET) DIORITE G) versus DISSEMINATED DIORITE and SYENITE F F c r i t « t t c r U v d . f . 2.15 2.70 - 4 . 0 3 2.69 44 3.10 3.35 8.49 2.69 44 3.29 2.70 - 0 . 4 2 2.58 257 4.42 2.70 4.29 2.58 241 6.07 2.70 - 2 . 9 5 2.58 228 2.15 2.91 9.79 2.70 41 4.72 2.70 3.39 2.58 238 6.72 2.70 2 . 8 5 2 . 5 8 225 MASSIVE(GLEN IRON SYENITE and AFTON) H) v e r s u s DISSEMINATED SYENITE F F c r i t * t t c r i f d . f . 2.02 7 .85 2.59 3.11 10 2.16 7.85 - 5 . 2 6 3.11 10 1.13 7.85 0.15 3.11 10 2.86 7.85 0.70 3.11 10 1.25 15.0 0.60 3.11 10 1.70 9.15 - 3 . 7 9 3.17 10 2.01 7 .85 - 2 . 8 1 3.11 10 2 . 2 5 7 .85 1.24 3.11 10 MASSIVE(GLEN IRON SYENITE and AFTON) I) versus DISSEMINATED SYENITE and DIORITE F F c r i t * t t c r i f d . f . 2 .83 5.04 2.59 2.88 18 3.54 5.04 - 7 . 0 4 2.88 18 1.17 5.04 0.11 2.88 18 2.86 5.04 0.45 2.88 18 1.26 5.04 1.26 2.88 18 1.93 5.67 - 5 . 0 1 2.95 15 3.26 5.04 - 3 . 9 9 2.88 18 3.41 5.04 1.55 2 . 8 8 18 MASSIVE (ALL SYENITE DEPOSITS) and DIORITE J) v e r s u s DISSEMINATED SYENITE and DIORITE F F c r i f t t c r i f d . f . 1.21 2.50 4.07 2.68 51 3.60 3.35 - 1 0 . 2 2 2.58 892 1.99 2.50 0.15 2.68 51 1.08 3.35 - 2 . 6 4 2.68 51 3.54 2.50 2.79 2.58 242 1.26 3.94 - 6 . 9 3 2.69 48 1.18 2.50 - 3 . 9 1 2 . 6 8 51 1.10 2.50 -1 .57 2.68 51 MASSIVE (ALL SYENITE DEPOSITS and DIORITE K) versus DISSEMINATED PICRITE F F c r i t -t t c r i t " d . f . 1.76 9.38 - 1 . 5 2 2.70 42 9.39 9.38 - 2 2 . 2 2.61 148 1.21 9.38 -14.1 2.70 42 1.95 9.38 - 5 . 6 3 2.70 42 3.41 3.55 - 1 8 . 2 2.70 42 1.36 9.38 - 3 . 9 9 2.70 42 1.04 3 . 5 5 9.19 2.70 42 9 . 8 6 9 . 3 8 - 1 5 . 8 5 2.61 156 TABLE 5.6 SUMMARY OF RESULTS OF F AND t  TEST PERFORMED IN TABLE 5 . 5 (A = n u l l hypothesis accepted; R = n u l l hypothesis rejected 1) ELEMENT Percent M A b N t l 1 1 t M U o l FORM (DEPOSIT) ROCK TEST Co Cr Mg Mn Ni Ti V Zn Accepted MASSIVE (MAGNET) DIORITE ± 2 S Z Air A Air R A R A R 6 2 . 5 A) versus MASSIVE(IRON CAP) DIORITE MASSIVE(GLEN IRON) SYENITE F R A A R R A R R 68.75 B) versus t A A A A A A A A MASSIVE (AFTON) SYENITE DISSEMINATED SYENITE F R A A A A A A A 93.75 C) versus t A A A A A A A A DISSEMINATED DIORITE DISSEMINATED SYENITE F A A A A A A A R 50 and DIORITE t R R R R R A R R D) versus DISSEMINATED PICRITE MASSIVE (MAGNET) DIORITE F A R R R A A A R 3 7 . 5 E) versus t A R A R R R R R DISSEMINATED DIORITE MASSIVE (MAGNET) DIORITE F A A R R R A R R 5 0 . 0 F) versus t R R A A A R A A DISSEMINATED SYENITE 1: Null hypothesis is that the two tested samples are from the same population. 2 : Null hypothesis accepted i f X i r 0ncap f a 1 1 s w 1 t h 1 n two standard deviations of X m a g n e t . TABLE 5J6 c o n t . MAGNETITE HOST FORM (DEPOSIT) ROCK ELEMENT Percent Accepted TEST Co Cr Mg Mn Ni T i V Zn G) MASSIVE (MAGNET) DIORITE versus DISSEMINATED SYENITE and DIORITE A R A R R A R R R R A R R R R R 25 H) MASSIVE (GLEN and AFTON) DISSEMINATED IRON SYENITE versus SYENITE [ A A A R A A A A A A A R A A A A 87.5 I ) MASSIVE (GLEN and AFTON) DISSEMINATED IRON SYENITE versus SYENITE and DIORITE A A A R A A A A A A A R A R A A 81.25 J) MASSIVE (ALL DEPOSITS) DISSEMINATED SYENITE and DIORITE versus SYENITE and DIORITE A R R R A R A • A R R A R A R A A 50 K) MASSIVE (ALL DEPOSITS) DISSEMINATED SYENITE and DIORITE versus MICRITE t A A R R A R A R A R A R A R R R 37.5 e x c e p t z i n c a r e s t a t i s t i c a l l y t h e same, a l l means e x c e p t t h o s e f o r t i t a n i u m a r e s t a t i s t i c a l l y d i f f e r e n t . These r e s u l t s emphasize t h e c l o s e g e n e t i c r e l a t i o n s h i p o f s y e n i t e and d i o r i t e i n t h e I r o n Mask b a t h o l i t h i n c o n t r a s t t o t h e d i s s i m i l a r i t y and u n i q u e n e s s o f p i c r i t e as n o t e d by N o r t h c o t e (1977). M i n o r element p o p u l a t i o n s i n m a s s i v e m a g n e t i t e from f o u r showings were compared t o see i f m i n o r element c o n t e n t v a r i e d s i g n i f i c a n t l y between showings o r was a f f e c t e d by h o s t r o c k t y p e . ( T a b l e 5.5 and 5.6). Comparison o f Magnet showing w i t h I r o n Cap showing, b o t h d i o r i t e h o s t e d , was done i n a n o n - r i g o r o u s manner because o f t h e d i f f e r e n c e i n sample s i z e s : 31 samples from Magnet showing v e r s u s 2 from I r o n Cap showing. F o r t h e s e showings, m i n o r element c o n t e n t s were c o n s i d e r e d t h e same i f t h e mean c o n t e n t of an element i n I r o n Cap m a g n e t i t e was w i t h i n two s t a n d a r d d e v i a t i o n s o f t h e mean f o r t h e same element i n Magnet m a g n e t i t e . Comparison o f l o d e s h o s t e d by s y e n i t e t o t h o s e h o s t e d by d i o r i t e shows a number o f e l e m e n t s have s i g n i f i c a n t d i f f e r e n c e s i ' ; i n t h e i r v a r i a n c e s , however, a l l means a r e s t a t i s t i c a l l y t h e same. Host r o c k t h e r e f o r e has no s t a t i s t i c a l l y d e f i n e a b l e e f f e c t on minor element c o n t e n t o f l o d e s and a l l l o d e s may l e g i t i m a t e l y be grouped t o g e t h e r i n f u r t h e r com-p a r i s o n s w i t h d i s s e m i n a t e d m a g n e t i t e . Comparison o f m i n o r e l e m e n t s i n m a s s i v e l o d e m a g n e t i t e t o t h o s e i n d i s s e m i n a t e d m a g n e t i t e r e s u l t s i n a more c o m p l i c a t e d p i c t u r e . M i n o r element c o n t e n t o f m a s s i v e m a g n e t i t e i s c l e a r l y s i g n i f i c a n t l y d i f f e r e n t f rom t h a t i n d i s s e m i n a t e d m a g n e t i t e i n p i c r i t e , w i t h t h e e x c e p t i o n o f 77 cobalt. The second main point shown i n t h i s section of the table i s that massive magnetite i s more c l o s e l y r e l a t e d to disseminated magnetite i n syenite than i n d i o r i t e as f a r as minor element contents are concerned. This r e l a t i o n s h i p i s brought out (with one exception) where massive magnetite i s compared with disseminated magnetite i n d i o r i t e or, disseminated magnetite i n both d i o r i t e and syenite. Wherever t h i s i s the case the n u l l hypothesis ( s t a t i s t i c a l s i m i l a r i t y ) i s rejected for most elements. However, comparison of lodes to only syenite-hosted disseminated magnetite r e s u l t s i n the n u l l hypothesis being accepted i n most cases. The exception to t h i s generalization i s massive magnetite i n syenite compared to disseminated magnetite i n syenite and d i o r i t e which r e s u l t s i n the n u l l hypothesis being accepted for most elements. Element abundances i n massive magnetite and syenite, d i o r i t e and p i c r i t e hosted disseminated magnetite are shown schematically on F i g . 5.6. Points brought out by the s t a t i s t i c a l t e s t s are well displayed i n t h i s f i g u r e , namely: (1) minor element abundances are very s i m i l a r i n d i o r i t e - and syenite-hosted disseminated magnetites; ( 2 ) minor elements i n disseminated magnetite i n p i c r i t e are markedly d i f f e r e n t from those i n a l l other magnetite; (3) minor elements i n massive magnetite show a s i m i l a r d i s t r i b u t i o n to those i n syenite- and diorite-hosted disseminated magnetite, except f o r strong depletion of chromium and titanium and weak de-p l e t i o n of vanadium i n massive, magnetite; and (4) i n s i x out of eight elements, abundances i n massive magnetite are closer to those i n disseminated magnetite i n syenite than to disseminated magnetite i n d i o r i t e . 78 4 . 0 3 .0 £ a a. 2 . 0 •2 1.0 0 / \/ o Mg V Ti Cr Co Zn SYMBOLS DISSEMINATED MAGNETITE HOST MASSIVE MAGNETITE HOST - • — Syenite 0 * - Picrite •A--- Diorite — r o - Syenite a diorite F i g . 5.6. Mean minor e l e m e n t c o n t e n t o f m a s s i v e and dissem4 i n a t e d m a g n e t i t e i n s y e n i t e , d i o r i t e and p i c r i t e , I r o n Mask b a t h o l i t h , B.C. E r r o r b a r s show the s t a n d a r d e r r o r o f t h e mean. Data i s from T a b l e s 5.3A and 5.3A. 79 5.5.2 I n t e r - e l e m e n t c o r r e l a t i o n and r e g r e s s i o n a n a l y s i s C o r r e l a t i o n c o e f f i c i e n t s and r e g r e s s i o n p l o t s f o r element p a i r s i n d i s s e m i n a t e d and m a s s i v e m a g n e t i t e were g e n e r a t e d u s i n g UBC TRP computer program (Le and T e n i s c i , 1978). C r i t i c a l c o e f f i c i e n t s were d e t e r m i n e d a t t h e 95 p e r c e n t c o n f i d e n c e l e v e l f r o m D i x o n and Massey (1969: T a b l e A-30a). C o r r e l a t i o n m a t r i c e s f o r e l e m e n t s i n d i s s e m i n a t e d and m a s s i v e m a g n e t i t e a r e shown i n T a b l e 5.7. M i n o r e l e m e n t s i n d i s s e m i n a t e d m a g n e t i t e show c o r r e l a t i o n s t y p i c a l o f t h o s e t h a t w o u l d be p r e d i c t e d on t h e o r e t i c a l grounds. F o r example, t i t a n i u m shows p o s i t i v e c o r r e l a t i o n w i t h e l e m e n t s o c c u r r i n g as d i v a l e n t i o n s i n m a g n e t i t e as w o u l d be e x p e c t e d w i t h c o u p l e d s u b s t i t u t i o n ( S e c t i o n 3.2). Z i n c shows p o s i t i v e c o r r e l a t i o n w i t h o t h e r d i v a l e n t i o n s w i t h t h e e x c e p t i o n o f n i c k e l . N i c k e l behaves ' o p p o s i t e l y t o o t h e r d i v a l e n t c a t i o n showing p o s i t i v e c o r r e l a t i o n w i t h vanadium and chromium, and n e g a t i v e c o r r e l a t i o n w i t h t h e o t h e r c a t i o n s . O s t a f i y c h u k et_ a l . (1973) s u g g e s t t h i s p o s i t i v e c o r r e l a t i o n i s a r e s u l t o f i n c r e a s e d s t a b i l i t y because of o v e r l a p o f t z g o r b i t a l s ( d x y , d x z , dyz) o f c a t i o n s i n o c t a h e d r a l p o s i t i o n s . They s u g g e s t b o n d i n g i s s t r o n g e r when one c a t i o n has h a l f t h e t z g o r b i t a l s f i l l e d ( e . g . w i t h : +3 +3 V , Cr ) and t h e o t h e r c a t i o n has t h e s e o r b i t a l s e i t h e r empty o r +2 c o m p l e t e l y f i l l e d ( e . g . w i t h N i ) . C o r r e l a t i o n c o e f f i c i e n t s f ound f o r d i s s e m i n a t e d m a g n e t i t e i n i n t r u s i v e r o c k s a r e compared t o t h o s e found f o r d i s s e m i n a t e d m a g n e t i t e i n R u s s i a n g r a n i t e s ( O s t o f i y c h u k £t_ a l . , i b i d . ) i n T a b l e 5.8. The 80 TABLE 5 . 7 CORRELATION MATRICES FOR EIGHT ELEMENTS  IN A) DISSEMINATED MAGNETITE. AND B) MASSIVE  (LODE) MAGNETITE ( S i n g l e u n d e r l i n i n g i n d i c a t e s a s i g n i f i c a n t c o r r e l a t i o n c o e f f i c i e n t a t t h e 95 p e r c e n t c o n f i d e n c e l e v e l ; d o u b l e u n d e r l i n i n g i n d i c a t e s a v e r y s t r o n g c o r r e l a t i o n ) CR CO KG MN NI TI V 7-N CR 1 . 0 0 CO - 0 . 2 2 . 1 . 0 0 MG - 0 . 1 8 0 . 0 3 1 . 0 0 MN - 0 . 2 8 0 . 1 6 0 . 7 3 1 . 0 0 NI 0 . 5 7 - 0 . 1 7 - 0 . 0 9 - 0 . 6 3 1 . 0 0 TI 0 . 0 4 0 . 3 1 0 . 7 1 0 . 6 3 - 0 . 2 5 1 . 0 0 V - 0 . 0 6 - 0 . 0 1 - 0 . 5 5 - 0 . 1 9 0 . 3 1 - 0 . 0 3 1 . 0 0 ZN - 0 . 0 8 0 . 3 3 0 . 9 8 0 . 8 1 - 0 . 4 6 0 . 5 2 - 0 . 3 9 1 . 0 0 • 3 " a a a A) S y e n i t e and d i o r i t e h o s t e d d i s s e m i n a t e d m a g n e t i t e (15 s a m p l e s ) r . 9 5 • 0 . 4 4 CR CO MG MN NI TI V ZN CR 1 . 0 0 CO - 0 . 0 6 1 . 0 0 MG 0 . 0 9 - 0 . 2 4 1 . 0 0 MN 0 . 0 8 0 . 7 2 - 0 . 1 3 2 . 0 0 NI 0 . 1 5 0 . 2 9 - 0 . 0 3 0 . 0 9 1 . 0 0 T I 0 . 4 1 - 0 . 1 0 - 0 . 1 6 . 0 . 2 5 - 0 . 2 1 1 . 0 0 V 0 . 2 9 - 0 . 2 8 •. - 0 . 1 9 - 0 . 4 9 0 . 2 0 0 . 3 5 1 . 0 0 ZN - 0 . 0 5 0 . 6 5 - 0 . 0 2 0 . 8 4 0 . 1 7 - 0 . 0 7 - 0 . 7 2 1 . 0 0 B ) M a s s i v e m a g n e t i t e (38 s a m p l e s ) r . 9 5 = o - z ? 81 TABLE 5 . 8 CORRELATION COEFFICIENTS FOR SELECTED ELEMENT P A I R S 111 MASSIVE  AND DISSEMINATED MAGNETITE FROM VARIOUS LOCATIONS ( S i n g l e u n d e r l i n i n g i n d i c a t e s a s i g n i f i c a n t c o r r e l a t i o n a t t h e 95 p e r c e n t c o n f i d e n c e l e v e l ; d o u b l e u n d e r l i n i n g I n d i c a t e s a v e r y s t r o n g c o r r e l a t i o n ) ELEMENT PAIR DISSEMINATED (GRANITE) CORRELATION COEFFICIENT DISSEMINATED (IRON MASK) MASSIVE (IRON MASK) MASSIVE ( K I K U i A ; T1+4 - M g + 2 T 1 + « - M n + 2 T1*4 - C o + 2 C r * 3 - N 1 + 2 - N1+2 T1+4 - C r * 3 T1*4 . V * 3 M n + 2 - M g * 2 M n * * - C o + 2 M n * ? - H 1 + 2 0 . 4 7  0 . 3 4 - 0 . 1 4 | 0 . 9 0 0 . 7 1  0 . 6 3 0 . 3 1 0 . 9 5 0 . 3 1 - 0 . 0 0 4 0 . 0 4 - 0 . 0 8 - 0 . 0 3 - 0 . 0 2 0 . 7 3 - 0 . 0 1 0 . 1 6 - 0 . 2 6 - 0 . 6 3 - 0 . 1 6 0 . 2 5 - 0 . 1 0 0 . 1 5 0 . 2 0 0 . 4 1  0 . 3 5 - 0 . 1 3 ( K 7 2 0 . 0 9 0 . 0 3 - 0 . 1 1 0 . 1 0 . 1 - 0 . 5 7 - 0 . 2 C - 0 . 0 3 "o.IF 0 . 4 9 n 35 1 5 38 36 r « 5X 0 . 2 9 0 . 4 4 0 . 2 7 0 . 2 9 R e f e r e n c e O s t a f i y c h u k T h i s s t u d y T h i s s t u d y P a r a k , 1 9 7 5 e t a l . , 1973 1 : I n s u f f i c i e n t d a t a i s a v a i l a b l e f o r c h r o m i u m i n K i r u n a m a g n e t i t e . 82 c o r r e l a t i o n c o e f f i c i e n t s i n b o t h s t u d i e s c o r r e s p o n d c l o s e l y w i t h two e x c e p t i o n s . Vanadium and n i c k e l show a v e r y s t r o n g p o s i t i v e c o r r e l a t i o n i n R u s s i a n g r a n i t e s b u t an e x t r e m e l y weak c o r r e l a t i o n i n I r o n Mask i n t r u s i o n s , and manganese and magnesium show no c o r r e l a t i o n i n R u s s i a n g r a n i t e s b u t show a s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n i n I r o n Mask i n t r u s i o n s . M a s s i v e m a g n e t i t e shows a p a t t e r n o f c o r r e l a t i o n c o e f f i c i e n t s t h a t i s v e r y d i f f e r e n t from t h a t f o r d i s s e m i n a t e d m a g n e t i t e ( T a b l e s 5.7 and 5.8). The most n o t a b l e d i f f e r e n c e i s t h a t t i t a n i u m does n o t show p o s i t i v e c o r r e l a t i o n s w i t h d i v a l e n t c a t i o n s . I t does show weak c o r r e l a t i o n w i t h chromium and vanadium; however, t h i s a p p e ars t o be caused by a few s p o r a d i c , h i g h t i t a n i u m v a l u e s . Z i n c does show s i g n i f i c a n t c o r r e l a t i o n s w i t h c o b a l t , manganese, and vanadium, and c o b a l t shows s i g n i f i c a n t c o r r e l a t i o n s w i t h manganese, n i c k e l and z i n c . Comparison of s i g n i f i c a n t c o r r e l a t i o n c o e f f i c i e n t s from I r o n Mask l o d e s w i t h t h o s e from K i r u n a m a g n e t i t e ( T a b l e 5.8) shows o n l y a s l i g h t s i m i l a r i t y . Most element p a i r s show no c o r r e l a t i o n , and o f t h o s e t h a t do o n l y manganese and c o b a l t a r e s i g n i f i c a n t i n b o t h d e p o s i t s . C o n d i t i o n s o f f o r m a t i o n would appear t o be h i g h l y v a r i a b l e d u r i n g f o r m a t i o n o f m a s s i v e m a g n e t i t e - a p a t i t e d e p o s i t s . 5.5.3 Comparison o f minor element r a t i o s I t was s u g g e s t e d i n S e c t i o n 3.4.2 t h a t m i n o r element r a t i o s might r e d u c e d a t a v a r i a t i o n and, t h e r e f o r e , be more u s e f u l f o r c o m p a r i s o n s . Mean, 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 o f t h e mean a r e g i v e n i n 83 T a b l e 5.9 f o r 14 mi n o r element r a t i o s i n s y e n i t e and d i o r i t e h o s t e d d i s s e m i n a t e d m a g n e t i t e . R a t i o s a r e f o r el e m e n t s showing s i g n i f i c a n t c o r r e l a t i o n ( T a b l e 5.7) o r f o r t h o s e commonly quoted i n t h e l i t e r a t u r e . These same r a t i o s a r e g i v e n i n T a b l e 5". 10 f o r d i o r i t e and s y e n i t e h o s t e d d i s s e m i n a t e d m a g n e t i t e . R a t i o s a r e f o r el e m e n t s showing s i g n i f i c a n t c o r r e l a t i o n ( T a b l e 5.7) o r f o r t h o s e commonly quoted i n t h e l i t e r a t u r e . These same r a t i o s a r e g i v e n i n T a b l e 5.10 f o r d i o r i t e and s y e n i t e h o s t e d m a s s i v e m a g n e t i t e . Means and v a r i a n c e s o f r a t i o s have been compared u s i n g F and t t e s t s i n t h e same manner d a t a was compared i n S e c t . 5.5.1. C a l c u l a t e d and c r i t i c a l F and t v a l u e s a r e t a b u l a t e d i n T a b l e 5.11 f o r t h r e e c o m p a r i s o n s , namely: r a t i o s i n s y e n i t e and d i o r i t e h o s t e d m a s s i v e m a g n e t i t e , r a t i o s i n s y e n i t e and d i o r i t e h o s t e d d i s s e m i n a t e d m a g n e t i t e , and r a t i o s i n a l l m a s s i v e m a g n e t i t e t o s y e n i t e p l u s d i o r i t e h o s t e d d i s -s e m i n a t e d m a g n e t i t e . R e s u l t s o f t h e s e t e s t s , summarized i n T a b l e 5.12, show t h a t t h e h o s t r o c k t y p e i s n o t r e f l e c t e d i n element r a t i o s i n m a g n e t i t e , e x c e p t f o r Mn/Zn and V/Zn r a t i o s w h i c h a r e d i s t i n c t l y d i f f e r e n t between m a s s i v e and d i s s e m i n a t e d m a g n e t i t e . F r i e t s c h (1970) c o n c l u d e d from h i s s t u d y t h a t minor element r a t i o s c o u l d n o t be used as i n d i c a t i o n o f g e n e s i s . I n s p e c t i o n o f F i g . 5.6 i n t h i s s t u d y , however, s u g g e s t s N i / C r m i g h t be u s e f u l i n t h i s r e g a r d . R a t i o s c a l c u l a t e d from v a l u e s t a b u l a t e d i n T a b l e s 5.15 and 5.18 f o r v a r i o u s m a g n e t i t e t y p e s a r e shown i n T a b l e 5.13. TABLE 5.9 SUMMARY OF DATA FOR MINOR ELEMENT RATIOS IN  DISSEMINATED MAGNETITE, IRON MASK BATHOLITH, B . C . HOST ROCK PARA-METER1 Co/Cr Co/Ni Co/Zn Mn/Co Mn/N1 Mn/Zn T i / C r Ti/Mn Ti/N1 T i / Z n V/Co V/Cr V/Ti V/Zn SYENITE n x 8 1.7 8 0.5 8 1.2 8 18.1 8 9.2 8 16.3 7 95.3 7 3.6 7 31.5 7 70.3 8 111.1 8 65.7 7 2.7 8 129.1 S 4.2 0.4 1.0 10.2 9.2 6.4 213.2 2.3 37.7 68.9 74.8 121.8 1.9 94.3 S/Tn- 1.48 0.13 0.35 3.60 3.24 2.28 80.58 0.81 13.33 24.36 26.43 43.06 0.67 33.3 DIORITE n 7 7 7 7 7 7 5 5 5 5 7 7 5 7 X 0.6 0.8 1.4 15.2 12.7 19.2 28.1 4.9 37.1 82.9 68.4 40.0 1.6 107.2 s 0.4 0.2 0.7 6.4 8.1 6.3 20.7 2.8 17.1 24.1 17.9 24.1 1.4 91.5 S/Tn 0.14 0.1 0.28 2.40 3.06 2.39 9.25 1.23 7.65 10.76 6.78 9.13 0.62 34.6 SYENITE + n 15 15 15 15 15 15 12 12 12 12 15 15 12 15 DIORITE X 1.2 O.G 1.3 16.8 10.8 17.6 67.3 4.1 33.8 75.5 91.2 53.7 2.2 118.9 s 3.0 0.3 0.9 8.5 8.6 6.3 161.7 2.5 29.8 53.3 58.5 88.6 1.7 90.3 S/frT 0.77 0.08 0.23 2.19 2.22 1.63 46.48 0.72 8.60 15.40 15.10 22.88 0.50 23.32 1: n = number of a n a l y s e s ; X = a r i t h m e t i c average; s = s t a n d a r d d e v i a t i o n ; S/fn= s t a n d a r d e r r o r of the mean. TABLE 5.10 SUMMARY OF DATA FOR MINOR ELEMENT RATIOS  IN MASSIVE MAGNETITE, IRON MASK BATHOLITH, B . C . HOST ROCK D AD A ELEMENT RATIOS PROPERTY r AKH" METER Co/Cr Co/Ni Co/Zn Mn/Co Mn/Ni Mn/Zn T i / C e Ti/Mn T i / N i T i / Z n V/Co V/Cr V/Ti V/Zn MAGNET + IRON CAP DIORITE n X S S/fn ' 33 231.5 3 3 0 . 8 33 0 . 6 0 0 . 2 0 . 0 4 33 3 . 0 1 .0 0.18 33 6 . 0 2 . 3 0.40 33 3.7 3 . 0 0.52 33 16.7 5.2 0.91 33 1486 2523 439.2 33 1.2 0 . 6 0.10 33 5 . 3 . 8 . 2 1.43 33 2 0 . 5 15.4 2.7 33 4 1 . 9 12.9 2.24 33 9086 12693 2210 33 8 . 2 4 . 2 0 . 7 3 33 121.4 49.7 8.65 AFTON + GLEN IRON SYENITE n X S S//7T 5 471.5 6 5 5 . 3 2 9 3 . 0 5 0 . 8 4 0.49 0.22 5 1 .33 1 .03 0.46 5 9.69 4.76 2.13 5 9.34 10.7 4.77 5 10.3 4 . 8 3 2.16 5 815.6 105.6 472.3 5 0.77 0.73 0.33 5 1.33 1.03 0.46 5 9.32 8.72 3 . 9 0 5 31.5 2 7 . 8 12.4 5 7106 10061 4499 5 7 .45 4.11 1.84 5 5 0 . 2 5 2 . 2 2 3 . 3 ALL OF ABOVE DIORITE a SYENITE n J S S//7T 38 2 6 3 . 0 3 8 4 . 5 6 2 . 4 38 0 . 6 0 . 3 0 . 0 5 38 2 . 8 1 . 2 0.19 38 6 . 5 2 . 9 0.47 38 4 . 5 4 . 9 0.79 38 15.9 5.6 0.91 38 1398.0 2382.8 387 38 1.1 0 . 6 0.10 38 5 . 0 7.7 1.25 38 19.0 15.1 2.45 38 4 0 . 6 15.5 2.51 38 88259 12278 1992 38 8 . 1 4 . 1 0.67 38 112.0 5 5 . 0 8 . 9 2 1: n = number of a n a l y s e s ; X = a r i t h m e t i c mean; s = standard d e v i a t i o n ; s/fTT= standard e r r o r of the mean. TABLE 5.11 CALCULATED F and t VALUES FOR FOURTEEN MINOR ELEMENT  RATIOS BETWEEN VARIOUS MAGNETITE SAMPLES. IRON MASK  BATHOLITH, B . C . MAGNETITE FORM HOST ELEMENT RATIOS TEST Co/Cr Co/Ni Co/Zn Mn/Co Mn/N1 Mn/Zn T i / C r Ti/Mn T i / N i T i / Z n V/Co V/Cr V/Ti V/Zn MASSIVE DIORITE versus MASSIVE SYENITE F F0.01 t d . f . t.005 3 . 9 2 4 . 0 0 - 1 . 5 8 36 2.72 1.50 4 . 0 0 - 2 . 0 0 36 2.72 1.06 4 . 0 0 3.47 36 2.72 4.28 4.00 -1.7 17 2.90 12.72 4 . 0 0 -1.17 16 2 . 9 2 1.16 13.85 2.58 36 2.72 5.71 13.85 0.58 36 2.72 1.48 4.00 1.46 36 2.72 63.4 13.85 2.65 738 2.58 3.12 13.85 1.57 36 2.72 4 . 6 4 4.00 0.82 17 2.90 1.59 13.85 0 . 3 3 36 2.72 1.04 13.85 0.37 36 2.72 1.10 4 . 0 0 2.97 36 2.72 DISSEMINATED DIORITE v e r s u s DISSEMINATED SYENITE F FQ01 t d . f . t.005 110 8.26 0.74 50 2 . 6 8 4 . 0 8.26 - 1 . 7 9 13 3.01 2.04 8 . 2 6 - 0 . 4 4 13 3.01 2.54 8.26 0.65 13 3.01 1.29 8 . 2 6 - 0 . 7 8 13 3.01 1.03 8.26 - 0 . 8 8 13 3.01 106 15.21 0.83 37 2.71 1.48 9.15 - 0 . 8 8 13 3.17 4 . 8 6 15.21 - 0 . 3 1 13 3.17 8.17 15.21 - 0 . 3 9 13 3.17 17.5 8.26 1.56 55 2.67 2 5 . 5 8.26 0 . 5 8 49 2 . 6 8 1.84 15.21 1.09 13 3.17 1.06 8.26 0.45 13 3.01 MASSIVE DIORITE and SYENITE versus DISSEMINATED DIORITE and SYENITE F F 0 0 1 t d . f . t.005 16,425 3.40 4 . 2 0 1370 2.58 1 3.40 - 4 . 2 8 51 2.68 1.78 3.40 4.37 51 2 . 6 8 8.59 2.55 - 4 . 5 9 215 2.60 3.08 2 . 5 5 - 2 . 6 7 250 2.60 1.27 2.55 - 0 . 9 6 51 2.68 217 4.00 3.42 1405 2.58 17.4 2.75 - 4 . 1 2 125 2.62 15.0 2.75 - 3 . 3 1 125 2.62 12.46 2.75 - 3 . 6 3 125 2.62 14.24 2.55 - 3 . 3 0 205 2.60 19200 3.40 4 . 4 0 1370 2 . 5 8 5.82 4 . 0 0 7.14 750 2.59 2.70 2.55 - 0 . 2 8 255 2.60 1- F = F value c a l c u l a t e d from data i n T a b l e 5 . 9 and 5 . 1 0 ; F 0 . 0 i = c r i t i c a l F value at the 99 percent c o n f i d e n c e l e v e l ; t = t v a l u e c a l c u l a t e d from data i n Tables 5 . 9 and 5 . 1 0 ; d . f . = degrees of freedom, t n . 0 0 5 = c r i t i c a l t v a l u e at 99 percent c o n f i d e n c e l e v e l . TABLE 5 . 1 2 SUMMARY OF RESULTS OF F AND t TESTS GIVEN IN TABLE 5 . 1 0 A = n u l l h y p o t h e s i s a c c e p t e d ; R = n u l l h y p o t h e s i s 1s r e j e c t e d 1 . MAGNETITE ELEMENT RATIOS % A c c e -pted FORM HOST TESTS Co/Cr Co/Ni Co/Zn Mn/Co Mn/Ni Mn/Zn T i / C r Ti/Mn T i / N i T1/Zn V/Co V/Cr V/Ti V/Zn MASSIVE DIORITE F A A A R R A A A R A R A A A 7 5 v e r s u s MASSIVE SYENITE t A A R A A A A A R A A A A R DISSEMINATED DIORITE F R A A A A A R A A A R R A A 8 6 v e r s u s DISSEMINATED SYENITE t A A A A A A A A A A A A A A MASSIVE DIORITE a SYENITE F R A A R R A R R R R R R R R 1 8 v e r s u s DISSEMINATED DIORITE t R R R R R A R R R R R R R A a SYENITE 1: N u l l h y p o t h e s i s i s t h a t the two t e s t e d samples are from the same p o p u l a t i o n . 88 T A B L E 5 . 1 3  SUMMARY OF NI/CR VALUES IN  MAGNETITE OF VARIOUS ORIGINS Ratios are calculated from data tabulated i n Tables 5 . 3 B , 5 . 1 5 , 5 . 1 6 , 5 . 1 8 MAGNETITE TYPE DISSEMINATED DISSEMINATED MASSIVE MAGNETITE-APATITE M v n ( ; ( 1 M , T T r . m  USSR GRANITES IRON MASK IRON MASK MISSOURI KIRUNA METASOMATIC HYDROTHERHAL Ni/Cr 0 . 3 0 . 7 7 18 . 48 0 - » 10 - » The r a t i o shows a general increase corresponding to decreasing temperature i n going from magnetite disseminated i n i n t r u s i v e rocks to magnetite-apa t i t e deposits to metasomatic and hydrothermal deposits. More data are needed to confirm t h i s trend e s p e c i a l l y for metasomatic and hydrothermal deposits. I f s u f f i c i e n t data were a v a i l a b l e to allow c a l c u l a t i o n of mean values f o r these two deposit types the trend could be interpreted better. 5.5.4 Concentration and Accumulation C o e f f i c i e n t s of Minor Elements i n Magnetite Concentration c o e f f i c i e n t s f o r massive and disseminated magnetite i n the Iron Mask b a t h o l i t h are shown i n Table 5.14. .These c o e f f i c i e n t s are obtained by d i v i d i n g the mean content of an element i n magnetite by the mean content of the element i n the earth's crust as given i n F r i e t s c h (1970). They, therefore, provide an i n d i c a t i o n of depletion ( c o e f f i c i e n t s l e s s than 1) or enrichment ( c o e f f i c i e n t s greater than 1) of elements i n magnetite r e l a t i v e to the crus t . From Table 5.14 i t can be seen that cobalt, n i c k e l and vanadium are enriched i n disseminated and massive magnetite, whereas chromium i s s l i g h t l y enriched i n disseminated magnetite only. Zinc shows s l i g h t depletion i n massive magnetite and s l i g h t 89 TABLE 5 . 1 4 CONCENTRATION - COEFFICIENTS AMD ACCUMULATION - COEFFICIENTS OF MINOR ELEMENTS  IN MASSIVE MAGNETITE AND DISSEMINATED MAGNETITE, IRON MASK BATHOLITH. B . C . ( s e e t e x t f o r d e t a i l s ) Co C r Mg ELEMEHT Mn HI T1 V Z n A v e r a g e ( g e o m e t r i c mean) a b u n d a n c e (ppm) i n m a s s i v e m a g n e t i t e , I r o n Mask b a t h . 78 1 6 4 0 0 500 134 427 2 8 8 0 3 2 A v e r a g e ( g e o m e t r i c mean) a b u n d a n c e (ppm) i n d i s s e m i n a t e d m a g n e t i t e . I r o n Mask b a t h . 49 128 6 3 0 0 700 93 2270 3 8 7 0 44-A v e r a g e c r u s t a l a b u n d a n c e (ppm) ( a s u s e d i n F r i e s t c h , 1970) 27 90 31000 1000 80 10000 100 4 0 C o n c e n t r a t i o n - c o e f f i c i e n t ( m a s s i v e m a g n e t i t e ) 2 . 9 0 . 0 1 0 . 2 0 . 5 1 . 7 0 . 0 4 2 8 . 8 0 . 8 C o n c e n t r a t i o n - c o e f f i c i e n t ( d i s s e m i n a t e d m a g n e t i t e ) 1 . 8 1 . 4 0 . 2 0 . 7 1 . 2 0 . 2 3 8 . 7 1 . 1 A c c u m u l a t i o n - c o e f f i c i e n t ( m a s s i v e m a g n e t i t e ) 5 . 7 A c c u m u l a t i o n - c o e f f i c i e n t ( d i s s e m i n a t e d m a g n e t i t e ) 7 . 3 90 e n r i c h m e n t i n d i s s e m i n a t e d m a g n e t i t e . F r i e t s c h (1970) on t h e b a s i s o f h i s s t u d y o f m a g n e t i t e i n Sweden, found c o n c e n t r a t i o n c o e f f i c i e n t s t o be u n r e l a t e d t o mode o f f o r m a t i o n o f m a g n e t i t e and c o n c l u d e d a more u s e f u l g e n e t i c i n d i c a t o r i s t h e a c c u m u l a t i o n c o e f f i c i e n t . F o r c o m p a r a t i v e p u r p o s e s a c c u m u l a t i o n c o e f f i c i e n t s w i l l be c a l c u l a t e d from d a t a i n t h i s s t u d y . A c c u m u l a t i o n c o e f f i c i e n t i s an aver a g e o f c o n c e n t r a t i o n c o e f f i c i e n t s . I n t h i s c a s e ( T a b l e 5.14) c o n c e n t r a t i o n c o e f f i c i e n t s f o r c o b a l t , chromium, manganese, n i c k e l , t i t a n i u m and vanadium have been summed and d i v i d e d by s i x . F r i e t s c h ( i b i d . ) f ound t h a t a c c u m u l a t i o n c o e f f i c i e n t s f o r t h e s e elements i n v o l c a n i c - s e d i m e n t a r y and metaso m a t i c m a g n e t i t e range between 1 and 2, w h i l e t h o s e i n magmatic i r o n o x i d e s a r e g r e a t e r t h a n 2. V a l u e s f o u n d i n t h i s s t u d y o f 5.7 f o r m a s s i v e m a g n e t i t e and 7.3 f o r d i s s e m i n a t e d m a g n e t i t e a r e , t h e r e f o r e , t y p i c a l o f magmatic m a g n e t i t e a p a t i t e d e p o s i t s . A c c u m u l a t i o n c o e f f i c i e n t as used by F r i e t s c h i s a poor e s t i m a t o r o f c o n c e n t r a t i o n c o e f f i c i e n t s . I n s p e c t i o n o f T a b l e 5.14 shows t h a t t h e a c c u m u l a t i o n c o e f f i c i e n t i s c o n t r o l l e d e n t i r e l y by t h e c o n c e n t r a t i o n c o e f f i c i e n t f o r vanadium; t h i s c o e f f i c i e n t b e i n g a t l e a s t 10 t i m e s g r e a t e r t h a n t h e n e x t l a r g e s t c o n c e n t r a t i o n c o e f f i c i e n t . Use of o n l y t h e co n -c e n t r a t i o n c o e f f i c i e n t f o r vanadium as an i n d i c a t o r o f m a g n e t i t e g e n e s i s would be as u s e f u l as t h e a c c u m u l a t i o n c o e f f i c i e n t ; A l t e r n a t i v e l y , an a c c u m u l a t i o n c o e f f i c i e n t based on l o g a r i t h m s o f c o n c e n t r a t i o n c o e f f i c i e n t s ( g e o m e t r i c mean) would be a b e t t e r e s t i m a t o r o f c e n t r a l t endency. 5.6 Comparison o f M i n o r Elements i n M a g n e t i t e Lodes i n I r o n Mask B a t h o l i t h  w i t h M i n o r Elements i n M a g n e t i t e D e p o s i t s i n O t h e r A r e a s Average m i n o r element c o n c e n t r a t i o n s i n m a g n e t i t e f r o m E l L a c o , C h i l e and e i g h t major m a g n e t i t e - a p a t i t e d e p o s i t s i n M i s s o u r i , U.S.A. and Sweden a r e t a b u l a t e d i n T a b l e 5.15. D i s t r i c t means f o r M i s s o u r i and Sweden have been c a l c u l a t e d f r o m d e p o s i t means. A r i t h m e t i c means o f elements i n I r o n Mask m a g n e t i t e - a p a t i t e d e p o s i t s a r e t a b u l a t e d i n T a b l e 5.16 f o r c o m p a r i s o n , and v a l u e s f o r M i s s o u r i , K i r u n a , and I r o n Mask a r e p l o t t e d d i a g r a m m a t i c a l l y i n F i g . 5.7. V a r i a n c e s arid means o f el e m e n t s i n I r o n Mask m a g n e t i t e - a p a t i t e d e p o s i t s have been s t a t i s t i c a l l y compared t o t h o s e o f M i s s o u r i and Swedish d e p o i s t s i n T a b l e 5.17. From t h i s t a b l e i t can be seen t h a t most means and v a r i a n c e s f o r m i n o r e l e m e n t s i n t h e I r o n Mask l o d e s a r e s t a t i s t i c a l l y t h e same t o t h o s e f o r M i s s o u r i and Sweden a t t h e 99 p e r c e n t c o n f i d e n c e l e v e l . S i g n i f i c a n t l y d i f f e r e n t v a r i a n c e s a r e f o u n d f o r chromium i n Swedish and M i s s o u r i d e p o s i t s . Swedish d e p o s i t s a l s o have s i g n i f i c a n t l y d i f f e r e n t means f o r magnesium and vanadium, and a s i g n i f i c a n t l y d i f f e r e n t v a r i a n c e f o r magnesium. T h i s s t a t i s t i c a l s i m i l a r i t y f o r most el e m e n t s i s r e a d i l y a p p a r e n t i n F i g . 5.7, and s u g g e s t s a s i m i l a r , i n t r u s i v e - m a g m a t i c o r i g i n f o r I r o n Mask m a g n e t i t e - a p a t i t e l o d e s , as f o r K i r u n a and M i s s o u r i i r o n d e p o s i t s . F o r c o m p a r i s o n w i t h I r o n Mask m a g n e t i t e d e p o s i t s , minor element d a t a f o r h y d r o t h e r m a l v e i n and metas o m a t i c m a g n e t i t e d e p o s i t s have been c o m p i l e d from t h e l i t e r a t u r e and t a b u l a t e d i n T a b l e 5.18. M i n o r element TABLE 5.15 AVERAGE MINOR ELHENT CONTENTS AND STANDARD DEVIATIONS OF MAJOR WORLD MAGNETITE  - (HEMATITE) - APATITE DEPOSITS (X = a r i t h m e t i c mean; s = standard d e v i a t i o n . ) DEPOSIT LOCATION NUMBER OF SAMPLES OF DEPOSITS PARAMETER Co Cr Mg Mn Ni T i V Zn Reference PEA RIDGE IRON MOUNTAIN MISSOURI MISSOURI 4 8 X ppm S X ppm S 54 53 41 19 1 0 4 4 436^  1295 625 409 3435 1678 73 49 33 15 1292 766 6011 3115 611 105 1142 409 100 130 K i s v a r s a n y i a P r o c t o r , 1967; p p . 4 5 7 , 458 BOURBON MISSOURI 14 X ppm S 54 58 5 14 1060 677 710 57 29 3257 2365 1359 611 127 AVERAGE MISSOURI 3 ( d e p o s i t s ) X ppm S 50 8 3 2 930 440 1580 1610 54 20 3520 2370 1040 380 119 17 KIIRUNAVAARA SWEDEN 36 X pmm S 120 90 1 3 760 370 720 330 260 74 800 830 1350 230 50 20 P a r a k , 1975; pp. 199, 200 LUOSSAVAARO SWEDEN 22 X pmm S 80 50 10 15 400 300 540 260 140 50 910 60 1140 280 60 40 P a r a k , 1975; pp. 2 0 0 , 201 LUOSSAJARVI SWEDEN 23 X ppm S 80 50 1 3 600 500 380 330 180 120 500 800 1070 330 30 20 P a r a k , 1975; pp. 2 0 1 , 202 TUOLLUVAARA SWEDEN 18 X ppm S 60 10 4 6 900 800 200 200 160 120 600 600 730 240 30 10 P a r a k , 1975; p. 202 AVERAGE SWEDEN 4 ( d e p o s i t s ) X ppm S 85 25 4 4 670 220 460 220 190 50 700 190 1070 260 40 15 MALMBERGET -(GALLIVARE) SWEDEN 2 X 105 <20 <3000 <200 135 600 -900 1300 35-60 F r i e t s c h , 1970; p . 21 EL LACO CHILE 3 Range - <30-100 - - - 100 -200 300 -400 - F r u t o s and O y a r z u n , 1975; p. 990 1: I n d i c a t e s v a l u e s are not g i v e n i n the r e f e r e n c e . TABLE 5.16 AVERAGE MINOR ELEMENT CONTENTS AND STANDARD DEVIATIONS OF IRON  MASK MAGNETITE - APATITE DEPOSITS (X = a r i t h m e t i c mean; s = standard d e v i a t i o n . Note: a r i t h m e t i c mean 1s used so t h a t comparisons can be made w i t h p u b l i s h e d d a t a . ) DEPOSIT LOCATION NUMBER OF SAMPLES OF DEPOSITS PARAMETER Co Cr Mg Mn Ni T i V Zn Reference IRON MASK (ALL MASSIVE) BRITISH COLUMBIA 4 ( d e p o s i t s ) X S 99 38 18 27 5500 2400 940 820 121 42 1300 1850 2700 530 77 82 T h i s study TABLE 5 . 1 7 STATISTICAL COMPARISON OF MAGNETITE - APATITE DEPOSITS IN THE  IRON MASK BATHOLITH TO MAGENTITE - (HEMATITE) - APATITE DEPOSITS  IN MISSOURI AND SWEDEN (A « n u l l h y p o t h e s i s a c c e p t e d ; R - n u l l hypothesis r e j e c t e d ) * A. Comparison o f V a r i a n c e s (F t e s t ) AREA PARAMETER Co Cr Mg Mn Ni T i V Zn P e r c e n t Accepted MISSOURI F c a l c u l a t e d 2 2 " . 6 1 8 2 2 9 . 8 3 . 8 6 4 . 4 1 1 . 6 4 1 . 9 5 2 3 . 3 F c r i t . (a. = 0 . 0 1 ) 9 9 . 2 9 9 . 2 9 9 . 2 3 8 . 8 9 9 . 2 3 0 . 8 9 9 . 2 9 9 . 2 8 7 . 5 N u l l h y p o t h . A R A A A A A A SWEDEN F c a l c u l a t e d 2 . 3 1 4 5 . 6 1 1 9 1 3 . 9 1 . 4 2 9 4 . 8 4 . 1 5 2 9 . 9 F c r i t . ( c c = 0 . 0 1 ) 2 9 . 5 2 9 . 5 2 9 . 5 2 9 . 5 2 9 . 5 2 9 . 5 2 9 . 5 2 9 . 5 . 6 7 . 5 N u l l h y p o t h . A R R A A R A A B. Comparison o f Means (t t e s t ) MISSOURI t c a l c u l a t e d 2.15 1.11 3.18 -0.70 2.51 -1.40 4.57 -0.85 d . f . 5 9 5 5 5 5 5 5 t c r i t . (oc=0.005) 4.03 3.25 4.03 4.03 4.03 4.03 4.03 4.03 87.5 N u l l h y p o t h . A A A A A A R A SWEDEN t c a l c u l a t e d 0.62 1.03 4.01 1.13 -2.11 0.65 5.52 0.89 d . f . 6 9 9 6 6 9 6 6 t c r i t . (oc = 0.005) 3.71 3.25 3.25 3.71 3.71 3.25 3.71 3.71 N u l l h y p o t h . A A R A A A R A 75 1: N u l l h y p o t h e s i s i s t h a t the two t e s t e d samples are from the same p o p u l a t i o n . TABLE 5.18 PUBLISHED MINOR ELEMENT CONTENTS OF MAGNETITE FROM HYDROTHERMAL VEIN DEPOSITS AND METASOMATIC DEPOSITS (X = a r i t h m e t i c mean) a) Hydrothermal V e i n D e p o s i t s DEPOSIT LOCATION NUMBER OF SAMPLES OF DEPOSITS PARAMETER Co Cr Mg Mn Ni T i V Zn Reference ABOVYAN U . S . S . R . l 9 ( T 1 , V , C r , Ni .Mg) 7 (Mn) X ppm Range 0 8800 3200-18000 900 600-1500 440 50-850 2500 800-6600 1500 600-3600 B o r i s e n k o et a l . 1969; pp.1414, 1415 DIFFERENT Range 0-2 0 - 2 4200-10000 2000-5000 0-20 0-2 0-100 <10 Hegemann and A l b r e c h t , 1954; p . 9 2 . b) Metasomatic D e p o s i t s RAZDAN OSOKINO ALEKSANDROVSK YEVSTYUNINSK VALUYEV SOKOLOVSK KACHARSK U . S . S . R . U . S . S . R . U . S . S . R . U . S . S . R . U . S . S . R . U . S . S . R . 7 ( T 1 , V , C r , Mn, Mg) 6 (Ni) 9 ( T 1 , V , M a , 1 0 ( C r ) ; 11 (Ni) 6 ( T 1 , V , C r , Mg) 4(Ma); 5 ( N i ) 2 ( T 1 , C r , N i , Mg) 1(V, Mn) 3 ( T i , V , C r , M n . N i . M g ) 5 ( T 1 , V , C r , Mn.Ni.Mg) X ppm Range X ppm Range X ppm Range X ppm Range X ppm Range X Range 100 3300 1900 0 1200 130 70- 1400- 900- _ 700- 70-190 10200 7400 4700 200 0 4600 1500 0 5400 2400 . 2700- 1000- - 2400- 1200 6600 2700 8400 -3500 0 3100 3500 6000 4200 1700 1100- 1900- 5000- 600- 480 6100 5800 6000 7900 2900 0 13500 3400 0 1100 300 _ 9600- _ _ 600- _ 17400 1500 0 3800 2900 0 0 190 _ 1700- 1200- _ 180 6000 4000 260 0 5000 2000 0 1900 160 2600- 1200- 800- 840 7600 3000 6600 2100 B o r i s e n k o et a l . , 1969; pp. 1414, 1415 -96 3.0 2 . 0 E Q . O 1.0 0 -1 .0 Mg V Ti Mn Cr Ni Co Zn SYMBOLS _ © _ _ iron Mask lodes Missouri deposits Kiruna deposits F i g . 5 .7. A r i t h m e t i c m e ans o f m i n o r e l e m e n t a b u n d a n c e s i n m a g n e t i t e f r o m I r o n M a s k l o d e s ; m a g m a t i c m a g n e t i t e -a p a t i t e d e p o s i t s f r o m M i s s o u r i , U.S.A., a n d K i r u n a , S w e d e n . D a t a i s f r o m T a b l e 5 . 1 3 . 97 3.0 2 .0 e Q . Q . 1.0 5 0 -1 .0 Mg V Ti Mn Cr Ni Co Zn — iron Mask lodes SYMBOLS HYDOTHERMAL VEIN — © — Abovyan, U S S R METASOMATIC _ _ . o — Various deposits, U.S.S.R F i g . 5 .8. A r i t h m e t i c m e ans o f m i n o r e l e m e n t a b u n d a n c e s i n . m a g n e t i t e f r o m I r o n M a s k l o d e s ; A b o v y a n h y d r o t h e r m a l v e i n d e p o s i t , USSR; a n d v a r i o u s m e t a s o m a t i c d e p o s i t s , USSR. D a t a i s t a b u l a t e d i n T a b l e s 5.12 a n d 5 . 1 4 . No d a t a i s a v a i l a b l e f o r Co a n d Z n i n USSR d e p o s i t s . 98 content of Abovyan hydrothermal deposit and mean minor element contents of f i v e metasomatic magnetite deposits i n the USSR are plotted on F i g . 5.8. From t h i s Figure and Table 5.18, hydrothermal magnetite appears to have s i g n i f i c a n t l y l e s s cobalt and chromium than do magmatic deposits. Metasomatic deposits have s i g n i f i c a n t l y lower chromium and n i c k e l contents. Possible use of the Ni/Cr r a t i o as an i n d i c a t o r of the genetic o r i g i n of deposits has been discussed i n Section 5.5.3. In summarizing t h i s section the minor element content of Iron Mask magnetite lodes shows a close s i m i l a r i t y to minor element patterns present i n Missouri and Kiruna magnetite deposits, for which an intrusive-magmatic o r i g i n i s postulated (Kisvarsanyi and Proctor, 1967; Geijer, 1960; F r e i t s c h , 1978). In contrast, minor element patterns i n hydrothermal vein and metasomatic magnetite deposits show s i g n i f i c a n t differences i n chromium, n i c k e l , and possibly cobalt content. 99 CHAPTER 6  DISCUSSION, SUMMARY AND CONCLUSIONS 6.1 I n t r o d u c t i o n P e t r o l o g i c and a n a l y t i c a l e v i d e n c e r e l a t i n g t o t h e o r i g i n o f m a g n e t i t e - a p a t i t e l o d e s i n t h e I r o n Mask b a t h o l i t h i s summarized and i n t e r p r e t e d i n t h i s c h a p t e r . I n t e r p r e t a t i o n s w i l l be d i r e c t e d t o w a r d f u l f i l l i n g t h e aims o f t h i s t h e s i s as o u t l i n e d i n C h a p t e r 1. These were: 1) d e t e r m i n e t h e g e n e s i s o f t h e l o d e s ; 2) d e t e r m i n e w h i c h u n i t o f t h e b a t h o l i t h t h e l o d e s o r i g i n a t e d f r o m , i f t h e y a r e magmatic i n o r i g i n ; and 3) d e t e r m i n e the g e n e t i c r e l a t i o n s h i p between t h e l o d e s and c o pper m i n e r a l i z a t i o n a t A f t o n . 6.2 G e n e s i s and O r i g i n o f M a g n e t i t e Lodes M a j o r and m i n o r element d a t a on m a g n e t i t e , and p e t r o l o g i c d e s c r i p t i o n s p r e s e n t e d : i n t h e p r e v i o u s c h a p t e r s , a l l o w a number o f c o n c l u s i o n s t o be drawn r e g a r d i n g t h e g e n e s i s o f m a g n e t i t e l o d e s i n t h e I r o n Mask b a t h o l i t h . A s y n t h e s i s o f t h e s e c o n c l u s i o n s s h o u l d p e r m i t development :of : f i n a l model f o r g e n e s i s o f m a g n e t i t e l o d e s i n t h e b a t h o l i t h . P e r t i n e n t g e o c h e m i c a l and t e x t u r a l f e a t u r e s , w i t h g e n e t i c c o n c l u s i o n s from t h e s e f e a t u r e s , a r e summarized i n T a b l e 6.1. 100 I n s p e c t i o n o f T a b l e 6.1 l e a d s t o t h e g e n e r a l c o n c l u s i o n t h a t t h e l o d e s a r e p r o b a b l y m a g m a t i c - p e g m a t i t i c i n j e c t i o n d e p o s i t s d e r i v e d from t h e b a t h o l i t h d u r i n g a l a t e s t a g e o f d i f f e r e n t i a t i o n . A metas o m a t i c o r i g i n c a n p r o b a b l y be d i s c a r d e d on t h e b a s i s o f 1) chromium and n i c k e l c o n t e n t s w h i c h e m p i r i c a l l y a r e n o t t h e same as r e p o r t e d i n me t a s o m a t i c d e p o s i t s , 2) t a b u l a r form o f l o d e s , and 3) s h a r p c o n t a c t s o f t h e l o d e s . An o r i g i n as a h y d r o t h e r m a l v e i n can be d i s c o u n t e d on t h e b a s i s o f h i g h e r chromium c o n t e n t t h a n o t h e r h y d r o t h e r m a l v e i n d e p o s i t s , and on t h e . o c c u r r e n c e o f i s o l a t e d m a g n e t i t e f r a g m e n t s , s e e m i n g l y suspended i n t h e l o d e s w h i c h have remained t h e r e f o r a t i m e s u f f i c i e n t f o r amp h i b o l e o r a p a t i t e c r y s t a l s t o grow r a d i a l l y around t h e f r a g m e n t s . I n t u i t i v e l y , t h e f l u i d n e c e s s a r y t o h o l d t h e fragment i n s u s p e n s i o n would be d e n s e r t h a n a h y d r o t h e r m a l s o l u t i o n . A p e g m a t i t i c o r magmatic f l u i d on t h e o t h e r hand c o u l d have an a p p r o p r i a t e d e n s i t y . To make t h e e x i s t e n c e o f a m a g n e t i t e - a p a t i t e m e l t f e a s i b l e a t g e o l o g i c a l l y a c c e p t a b l e t e m p e r a t u r e s a h i g h v o l a t i l e c o n t e n t i s p r o b a b l y n e c e s s a r y . The h i g h v o l a t i l e c o n t e n t o f E l Laco m a g n e t i t e f l o w , as i n d i c a t e d by i t s porous vuggy n a t u r e has been emphasized by H a g g e r t y ( 1 9 7 0 ) . The a p p a r e n t l y h i g h v o l a t i l e c o n t e n t o f m a g n e t i t e - a p a t i t e dykes has been p o i n t e d out by P a r k (1972) and G e i j e r ( 1 9 6 7 ) . P r e s e n c e o f a p a t i t e s u g g e s t s t h a t c h l o r i n e and p o s s i b l y f l u o r i n e a r e s i g n i f i c a n t v o l a t i l e components. A model f o r t h e o r i g i n o f m a g n e t i t e l o d e s i s p r e s e n t e d . I t i s based on e x p e r i m e n t a l e v i d e n c e t h a t a m e l t o f m a g n e t i t e and a p a t i t e , i n t h e a p p r o p r i a t e p r o p o r t i o n s , i s i m m i s c i b l e w i t h a d i o r i t i c s i l i c a t e m e l t . 101 TABLE 6.1 SUMMARY OF GEOCHEMICAL AND TEXTURAL FEATURES OF MAGNETITE IN  THE IRON MASK BATHOLITH, B.C., WITH GENETIC SIGNIFICANCE OF FEATURES GENETIC SIGNIFICANCE FEATURE REFERENCE l a ) L a r g e a m p h i b o l e and a p a t i t e c r y s t a l s a r e o r i e n t e d p e r p e n d i c u l a r l y t o t h e w a l l s o f l o d e s . l b ) Amphibole l o c a l l y i s a r r a n g e d r a d i a l l y a r o u n d m a g n e t i t e f r a g m e n t s i n l o d e s . 2) Around t h e m a g n e t i t e l o d e s no t h e r m a l e f f e c t s were o b s e r v e d and o n l y m i n o r h y d r o t h e r m a l a l t e r a t i o n o f h o s t r o c k was n o t e d . 3) H i g h e s t c o n c e n t r a t i o n s o f t i t a n i u m and l o w e s t concen-t r a t i o n s o f c o b a l t o c c u r i n th e c e n t r e o f l o d e s . 4) M i n o r element p a t t e r n : i n .'! I r o n Mask l o d e s i s s t a t i s t i -c a l l y .the same as t h o s e f o r m a g n e t i t e f r o m K i r u n a and M i s s o u r i d e p o s i t s . 5) . M i n o r element abundances r e p o r t e d i n h y d r o t h e r m a l v e i n and me t a s o m a t i c m a g n e t i t e d e p o s i t s show d i s t i n c t d i f f e r e n c e s t o t h o s e i n I r o n Mask l o d e s . S e c t . 2.5.2 P l a t e 2.7 S e c t . 2.5.2 P l a t e 2.10 S e c t . 2.5.2 S e c t . 5.4.2 F i g s . 5.4 & 5.5 S e c t . 5.6-F i g . 5.7 S e c t . 5.6 F i g . 5.8 H y d r o t h e r m a l o r peg-m a t i t i c o r i g i n . M a g m a t i c - p e g m a t i t i c o r i g i n . Low t e m p e r a t u r e o f c r y s t a l -l i z a t i o n and low v o l a t o i l e c o n t e n t o f l o d e s compared t o h y d r o t h e r m a l systems. B e h a v i o u r o f c o b a l t s u g g e s t s c o o l i n g o f a m a g n e t i t e m e l t f r o m m a r g i n s i n toward t h e c e n t r e . B e h a v i o u r o f t i t a n i u m i s t h e o p p o s i t e t h a t w o u l d be e x p e c t e d , however, t h i s c o u l d be caused by c o m p l e x i n g o f t i t a n i u m i n a v o l a t i l e r i c h e n v i ronment (Ringwood, 1955b). S i m i l a r g e n e s i s (magmatic i n j e c t i o n ) f o r I r o n Mask, K i r u n a , and M i s s o u r i d e p o s i t s . Lodes a r e n o t h y d r o t h e r m a l v e i n o r m e t a s o m a t i c i n o r i g i n . 102 TABLE 6.1 c o n t i n u e d FEATURE REFERENCE GENETIC SIGNIFICANCE 6) S i m i l a r low m i n o r element S e c t . 5.2 c o n t e n t s o c c u r i n m a g n e t i t e F i g . 5.1 f r o m d i o r i t e , s y e n i t e and l o d e s . 7a) G r o s s c o m p o s i t i o n s of mag- S e c t . 5.2 n e t i t e from d i o r i t e and F i g . 5.1 s y e n i t e h o s t e d d i s s e m i n a t e d m a g n e t i t e a r e e x t r e m e l y s i m i l a r . Low t e m p e r a t u r e o f c r y s t a l -l i z a t i o n f o r l o d e s and i n t r u s i v e m a g n e t i t e . C l o s e g e n e t i c r e l a t i o n s h i p between d i o r i t e and " ' s y e n i t e . 7b) Gross c o m p o s i t i o n s o f mag-n e t i t e d i s s e m i n a t e d i n i n t r u s i v e r o c k s and o f m a g n e t i t e i n l o d e s a r e i n d i s t i n g u i s h a b l e . 8) M i n o r element c o n t e n t o f d i s s e m i n a t e d m a g n e t i t e i n i n t r u s i v e r o c k s i s s i m i l a r t o t h a t i n l o d e s , e x c e p t f o r d e p l e t i o n o f C r , T i , V i n l o d e s . 9) C o m p o s i t i o n s and m i n o r element c o n t e n t o f p i c r i t e a r e u n i q u e l y d i f f e r e n t t h a n m a g n e t i t e i n l o d e s , i n d i o r i t e o r i n s y e n i t e . 10) M i n o r element c o r r e l a t i o n s a r e d i f f e r e n t between d i s s e m i n a t e d and m a s s i v e m a g n e t i t e . 11) An a n g u l a r fragment o f m a s s i v e m a g n e t i t e o c c u r s i n f i n e - g r a i n e d p l a g i o c l a s e p o r p h y r y o f C h e r r y Creek s u i t e . 12) M a g n e t i t e i s i n t e r s t i t i a l i n d i o r i t i c r o c k s and l a t e c r y s t a l l i z i n g i n most a l k a l i c r o c k s . S e c t . 5.2 F i g . 5.1 S e c t . 5.5.1 F i g . 5.6 S e c t . 5.4.2 F i g . 5.6 S e c t . 5.5.2 T a b l e s 5.7 & 5.8 S e c t . 2 S e c t . 2 C l o s e g e n e t i c r e l a t i o n s h i p between i n t r u s i v e r o c k s and l o d e s . Lodes a r e g e n e t i c a l l y r e l a t e d t o s y e n i t e and d i o r i t e b u t were emplaced a t a l a t e r s t a g e of d i f f e r e n -t i a t i o n , and t h e r e f o r e , a t a l o w e r t e m p e r a t u r e . P i c r i t e i s n o t g e n e t i c a l l y r e l a t e d t o d i o r i t e , s y e n i t e o r m a g n e t i t e l o d e s . There a r e g e n e t i c d i f f e r e n c e s o r i g i n i s n o t one o f s i m p l e f i l t e r p r e s s i n g and i n -j e c t i o n o f magmatic m a g n e t i t e . Magmatic a c t i v i t y c o n t i n u e d a f t e r i n j e c t i o n o f m a g n e t i t e -a p a t i t e i n t o f r a c t u r e s . I r o n i s c o n c e n t r a t e d i n t h e r e s i d u a l magma. 103 D i f f e r e n t i a t i o n and c o n c e n t r a t i o n o f m a g n e t i t e and a p a t i t e can t h u s be e x p l a i n e d e a s i l y . 6.3 I m m i s c i b l e M e l t Model 6.3.1 E x p e r i m e n t a l E v i d e n c e E x p e r i m e n t s by P h i l p o t t s (1967) on t h e sys t e m m a g n e t i t e - a p a t i t e -d i o r i t e i n d i c a t e t h a t a m a g n e t i t e - a p a t i t e m e l t i s i m m i s c i b l e w i t h a d i o r i t i c m e l t when a p a t i t e forms 20 t o 35 w e i g h t p e r c e n t o f t h e m a g n e t i t e -a p a t i t e m e l t . A s c h e m a t i c summary of P h i l p o t t s ; r e s u l t s i s shown i n ' F i g . 6.1. I n t h e system m a g n e t i t e - f l u o r a p a t i t e a e u t e c t i c o c c u r s n e a r 25 w e i g h t p e r c e n t f l u o r a p a t i t e a t a t e m p e r a t u r e o f a p p r o x i m a t e l y 1400°C ( F i g . 6 . I B ) , t h u s a e u t e c t i c c o m p o s i t i o n i s i m m i s c i b l e w i t h a d i o r i t i c m e l t . M a g n e t i t e - a p a t i t e dykes a s s o c i a t e d w i t h a n o r t h o s i t e s and some a l k a l i n e complexes commonly have a c o m p o s i t i o n o f o n e - t h i r d a p a t i t e and t w o - t h i r d s m a g n e t i t e w h i c h c o r r e s p o n d s c l o s e l y w i t h t h e e x p e r i m e n t a l e u t e c t i c c o m p o s i t i o n . P h i l p o t t s , t h e r e f o r e c o n c l u d e d t h a t t h e m a g n e t i t e and a p a t i t e i n d e p o s i t s a s s o c i a t e d w i t h a n o r t h o s i t e s were s e p a r a t e d as an i m m i s c i b l e m e l t from a magma u n d e r g o i n g s t r o n g d i f f e r e n t i a t i o n t oward a m a g n e t i t e - a p a t i t e e u t e c t i c . The sequence o f r o c k f o r m a t i o n f o r a n o r t h o s i t e c o mplexes, a c c o r d i n g t o P h i l p o t t s i s : a c c u m u l a t i o n o f l a r g e amounts o f p l a g i o c l a s e w i t h m i n o r o l i v i n e , o r t h o p y r o x e n e o r c l i n o p y r o x e n e l e a d i n g t o i r o n e n r i c h m e n t i n t h e r e s i d u a l magma and subsequent c r y s t a l l i z a t i o n o f o x i d e - a p a t i t e r i c h d i o r i t e s . A t t h i s s t a g e t h e magma im p i n g e s on an i m m i s c i b i l i t y f i e l d r e s u l t i n g i n s e p a r a t i o n o f an o x i d e - a p a t i t e r i c h m e l t . C o n t i n u e d d i f f e r e n t i a t i o n r e s u l t s i n f o r m a t i o n o f s y e n i t i c r o c k s . 104 F i g . 6.1A. S c h e m a t i c i s o t h e r m a l s e c t i o n ( a t 1420 C) t h r o u g h t h e s y s t e m m a g n e t i t e - a p a t i t e -d i o r i t e , s h o w i n g t h e p o s s i b l e e x t e n t o f t h e t h r e e ( 3 L ) a n d two l i q u i d ( 2 L ) f i e l d s ( f r o m P h i l p o t t s , 1 9 6 7 ) . 1420 14!00' g n e t i t e F l u o r a p a t i t e F i g . 6 . I B . S c h e m a t i c T-X s e c t i o n f o r m a g n e t i t e a n d a p a t i t e . D a t a i s e x t r a p o l a t e d f r o m F i g . 6.1A a b o v e 105 P h i l p o t t s e x p e r i m e n t s were c a r r i e d o u t a t a p p r o x i m a t e l y 1400 C; an u n r e a s o n a b l y h i g h t e m p e r a t u r e f o r g e o l o g i c p r o c e s s e s . A d d i t i o n o f v o l a t i l e s , s u c h as f l u o r i n e , i s b e l i e v e d t o l o w e r t h e m e l t i n g p o i n t t o g e o l o g i c a l l y more l i k e l y t e m p e r a t u r e s . R u i z (1965) and Lla u m e t (1967) b e l i e v e a p a t i t e components ( e s p e c i a l l y f l u o r i n e and c h l o r i n e ) may l o w e r t h e c r y s t a l l i z a t i o n t e m p e r a t u r e o f m a g n e t i t e t o about 1,000°C t o 800°C, t h u s making m a g n e t i t e m e l t f e a s i b l e . 6.3.2 A p p l i c a t i o n o f I m m i s c i b l e M e l t Model t o I r o n Mask B a t h o l i t h The a p p l i c a b i l i t y o f t h e i m m i s c i b l e m e l t model t o t h e I r o n Mask b a t h o l i t h i s s u g g e s t e d by t h e s i m i l a r n a t u r e o f I r o n Mask m a g n e t i t e l o d e s t o t h o s e o c c u r r i n g i n a n o r t h o s i t e s , and by a number o f s i m i l a r i t i e s between t h e I r o n Mask b a t h o l i t h and t h e a n o r t h o s i t e complexes t o w h i c h P h i l p o t t s a p p l i e d h i s model. Analogous t o a n o r t h o s i t e s , t h e I r o n Mask b a t h o l i t h c o n t a i n s p l a g i o c l a s e and i r o n o x i d e r i c h c u m u l a t e s o f d i o r i t i c c o m p o s i t i o n and l a t e s t a g e s y e n i t i c and m o n z o n i t i c r o c k s . The I r o n Mask b a t h o l i t h a l s o a p p e a r s t o have d i f f e r e n t i a t e d t o w a r d a p o s s i b l e m a g n e t i t e - a p a t i t e e u t e c t i c . Data f r o m Mathews (1941) i n d i c a t e s t h a t t h e amount o f m a g n e t i t e i n t h e b a t h o l i t h d e c r e a s e s i n l a t e r d i f f e r e n t i a t e s w h i l e t h e amount o f a p a t i t e i n c r e a s e s . A summary o f d a t a ( T a b l e 6.2) from A p p e n d i x B and Mathews ( i b i d . ) f o r r o c k s a t t h e n o r t h -west end of t h e b a t h o l i t h i n d i c a t e s a d i s c o r d a n t d e c r e a s e i n t h e amount o f d i s s e m i n a t e d an an i n c r e a s e i n t h e amount o f a p a t i t e between d i o r i t i c and s y e n i t i c r o c k s . T h i s d i s c o r d a n c e between m a g n e t i t e i n d i o r i t e 106 (Pothook u n i t ) v e r s u s s y e n i t e ( C h e r r y Creek u n i t ) i s shown i n F i g . 6.2. Assuming t h a t t h e m a g n e t i t e and a p a t i t e i n t h e r o c k a r e a r e s i d u a l from any p o t e n t i a l l y s e p a r a t e d i m m i s c i b l e m a g n e t i t e - a p a t i t e m e l t , i t would appear from d a t a i n T a b l e 6.2 t h a t m a g n e t i t e - a p a t i t e approached a e u t e c t i c . c o m p o s i t i o n and became i m m i s c i b l e w i t h a s i l i c a t e m e l t when t h e magma became s y e n i t i c i n c o m p o s i t i o n . T h i s c o n c l u s i o n i s s u p p o r t e d by t h e e x p e r i m e n t a l e v i d e n c e ( P h i l p o t t s , i b i d . ) t h a t a m a g n e t i t e -a p a t i t e m e l t c o n t a i n i n g 20 t o 35 w e i g h t p e r c e n t a p a t i t e (near o r a t a e u t e c t i c c o m p o s i t i o n ) i s i m m i s c i b l e w i t h a d i o r i t i c m e l t . TABLE 6.2 VOLUME PERCENT DISSEMINATED MAGNETITE, APATITE  AND APATITE/APATITE+MAGNETITE FOR DIORITIC AND  SYENITIC ROCKS, IRON MASK BATHOLITH, B.C. (Data from A p p e n d i x B and Mathews, 1941) ARITHMETIC AVERAGE . ROCK TYPE % DISSEMINATED % ACCESSORY %APATITE X 100 MAGNETITE APATITE %APATITE+%MAGNETITE D i o r i t e 8.5 t r a c e 1 (Pothook) S y e n i t e 3.5 0.8 20 ( C h e r r y Creek) I : Number o f samples: m a g n e t i t e i n d i o r i t e - 6 ; m a g n e t i t e i n s y e n i t e - 5 a p a t i t e i n d i o r i t e - 2 ; a p a t i t e i n s y e n i t e - 3 . 2: T r a c e was a r b i t r a r i l y a s s i g n e d 0.1%. 107 I y V V V V V V V V V V V v v v v v v v v v v v v v v v v v v . V V V V V V V V V V V V V V V V V V V V V v w w w w w w v w w w v w w , W W V V " ; V V V V V V L x / v w v w \ W V V V W V x V V V V V V V V V ' x v v v v v v v v v v " , v v v v v v v v v v V - / V V V V V V V V V V V V x , V V V V V V V V V V V v ' v v v v v v v y j v > -v v v v v v KM Jl V / V V V V W x AFTON X . X X X X X X X . X X X X X X X V V V V V V V V V V V v ' V V V V V V V V V V V . x ^ s y v v v v v v v v v v X X X/ v v v v v v v v v v . V V V V V V V V V V V V X X X X X X X X X ™ Y x x . — N x X X X X X X X X ^- i^V V V V V V V V V V V V V W W V V v v v v v v x ' " ^ C V w w w w ^ ' V V V V V V V V x x x > s ^ v v W W X X X X X X X X X X X X X X X X X X \ x >• M A b N t l V lx I ^SHOWING pi / I \ / X X X X X X X X X X X ^ / IRON u £ SHOVVIIVG ^4- .J- - | _ 4~ + I \ Jr + + + 4- + f f f f + 4-4- + 4* *4° + 4* + 4. 4- +. ^ T~j- f x ^ N ^ '4- 4- 4- 4- 4 - + 4-+ + + + + + + + * - + + * 4 - + + + PERCENT DISSEM. MAGNETITE \ 1 / / A X V X Y2 Cherry Creek Unit; Breccia Pothook diorite l+^ -f] Iron Mask Hybrid ^ Nicola volcanics Magnetite - apatite dyke (dipping) 0-2 • -4 • - 6 • -8 • -10 • -12 • F i g . 6.2. S i m p l i f i e d g e o l o g y ( a f t e r N o r t h c o t e , 1 9 7 7 a ) s h o w i n g a b u n d a n c e o f d i s s e m i n a t e d m a g n e t i t e a n d d i s t r i b u t i o n o f m a g n e t i t e - a p a t i t e d y k e s i n P o t h o o k ( d i o r i t e ) a n d C h e r r y C r e e k ( s y e n i t e ) u n i t s . D a t a i s f r o m -A p p e n d i x B, a n d M a t h e w s ( 1 9 4 1 ) . 108 Separation of immiscible magnetite-apatite from a s y e n i t i c or a l k a l i c magma also i s indicated by the minor element analyses (Section 5.5.1) which showed that minor element contents i n massive magnetite match more c l o s e l y disseminated magnetite i n syenite than disseminated magnetite i n d i o r i t e . The proposed model f o r genesis of magnetite-apatite lodes i n the Iron Mask b a t h o l i t h i s shown schematically i n F i g . 6.3. C r y s t a l l i z a t i o n and f r a c t i o n a t i o n of the i n t r u s i o n by a combination of gravity s e t t l i n g and c r y s t a l l i z a t i o n c o n c e n t r i c a l l y inward, as shown i n the model, has been proposed for the l i t h o l o g i c a l l y s i m i l a r , a l k a l i c Copper Mountain i n t r u s i o n (Montgomery, 1967; Preto, 1972). Lost Horse i n t r u s i v e phase from t h i s i n t r u s i o n (Preto, i b i d . ) are generally i n d i s t i n g u i s h a b l e i n texture and composition from Cherry Creek phase (C.I. Godwin, 1979, pers. comm.). Both also contain s i m i l a r looking i n t r u s i v e breccia phases. The Copper Mountain g r a n i t i c rocks host a number of magnetite bodies which were generally referred to as "magnetite breccias" by Preto (1972; p. 83). Near the Ingerbelle mine "magnetite breccias" are magnetite-apatite lodes i n d i s t i n g u i s h a b l e from those i n the Iron Mask b a t h o l i t h (C.I. Godwin and L. Kornze, 1978, pers. comm.). An a d d i t i o n a l s i m i l a r i t y between Iron Mask and Copper Mountain intrusions i s the occurrence of porphyry copper deposits i n both. These s i m i l a r i t i e s j u s t i f y the use of a s i m i l a r f r a c t i o n a t i o n scheme here. The sequence of events pictured i n F i g . 6.3 i s : 109 S U R F A C E vvvvvvvvvvv vvvvvvvvvvv vvvvvvvvvvv vvvvvvvvv vvvvvv vvv vvv. V V V V V V V V V V V V vvvvv" ^ V V V V V V . ^ V V V v v v v v N v - V V V V V V V V •vvv V V V V V V V V V POTHOOK STAGE^v -V—V—Y V v , I  »T V V V V V V V V V V N j vvvvvvvvv^ V V V V V V V V V \ vv ^ vvvv\+ - J -vvv v v v V V V V V v U J . V V V V V " * S U R F A C E B vvvvvvvvvv VVVVvvvvvv vvvvvvvvvv vvvvvvvvvv vvvvvvvvv V V V V v v v V V V V V ) / • V V V V • V V V V V vv| ' V V V V V V V V V V ' V V V V V vvvvvv V V V V V V V ' V V V V V " V V V IMMISCIBLE STAGE V V V V V V V V V V V v \ VVVVvvvvvvvvv vvvvvvvvvvvvv vvv V 1 vvv V V V V V vvvvvv ' V V V V V V vvvvvv S U R F A C E S U R F A C E , . . v "v V V V v v V V V V " ' V V V V V V V vvv V vvv ' V V V V V v v v ' V V V V V ' V V vv : V V V Vj vvv vvv vvv 'vvv " V V V V vvvvv V V V V V ' V V V V V V V V •vvvvvvvvv vvvvvvvv v\^ + C. MAGNET STAGE '^^vvvv 4 v v v v v v " V ' * v f " / V V V V V V W V V V V \ \ | / V V V V V V V V V V V ^ ' - 1 /vvvvvvv — / V V V V V " 'wvv; ' ' V V V . ' v vv/ • v V vvv' / V V vvvv" ' W W . ^ V V V V V V V . ' V V V V V V V V V , vvvvvvvvv •vvvvvvv 'vvvvvvvv1 D.AFTON STAGE 'vvvvvvv^ vvvvvv SYMBOLS si Cherry Creek Breccia Nicola agglomerate x x xj Cherry Creek Unit Massive magnetite-apatite (meltjlode) Pothook diorite Iron Mask Hybrid F i g . 6.3. Diagrammatic c r o s s - s e c t i o n s ( l o o k i n g e a s t ) i l l u s t r a t i n g g e n e s i s o f m a g n e t i t e - a p a t i t e l o d e s i n t h e n o r t h w e s t end o f I r o n Mask p l u t o n , B.C. ( c f . F i g . 6.2).. (A) POTHOOK STAGE: C r y s t a l s e t t l i n g o f p l a g -i o c l a s e and pyroxene; to form Pothook d i o r i t e . R e s i d u a l magma becomes e n r i c h e d i n i r o n . (B) IMMISCIBLE STAGE: M a g n e t i t e and a p a t -i t e f o r m an i m m i s c i b l e m e l t i n r e s i d u a l a l k a l i c magma. D r o p l e t s s e t t l e and p o o l i n low a r e a s on f l o o r o f magma chamber. (C) MAGNET STAGE: I n t e r n a l p r e s s u r e causes i n j e c t i o n o f m a g n e t i t e - a p a t i t e m e l t i n t o f r a c t u r e s i n the c o n s o l i d a t e d p o r t i o n s o f t h e C h e r r y Creek 'fj U n i t . (D) AFTON STAGE: E x p l o s i v e emplacement o f Ch e r r y Creek - J . b r e c c i a s ( c f . N o r t o n and C a t h l e s , 1973) and copper m i n e r a l i z a t i o n . 110 A. POTHOOK STAGE C r y s t a l s e t t i n g o f p l a g i o c l a s e and pyr o x e n e t o form P o t k o o k d i o r i t e . W i t h c o n t i n u e d d i f f e r e n t i a t i o n t h e r e s i d u a l magma becomes i n c r e a s i n g l y r i c h i n i r o n as e v i d e n c e d by i n t e r s t i t i a l m a g n e t i t e i n Pothook d i o r i t e ( T a b l e 6.2). B. IMMISCIBLE STAGE Near t h e p o i n t where t h e r e s i d u a l magma becomes a l k a l i c i n c h a r a c t e r , m a g n e t i t e and a p a t i t e r e a c h a e u t e c t i c c o m p o s i t i o n and t o g e t h e r form an i m m i s c i b l e m e l t w i t h t h e s i l i c a t e magma. I m m i s c i b l e o x i d e d r o p l e t s s e t t l e t o t h e bottom o f t h e magma chamber f o r m i n g bands, l a m i n a t i o n s and p o o l s o f m a g n e t i t e - a p a t i t e f l u i d i n Pothook d i o r i t e a l o n g t h e m a r g i n s o f t h e magma chamber ( c f . Ramdohr, 1969; p. 8 ) . C. MAGNET STAGE R e s i d u a l a l k a l i c magma, now d e p l e t e d i n i r o n ( T a b l e 6.2), c o n t i n u e s c r y s t a l l i z i n g as s y e n i t e ( C h e r r y Creek u n i t ) . E x t r u s i o n o f N i c o l a a g g l o m e r a t e c o n t a i n i n g C h e r r y Creek f r a g m e n t s ( N o r t h c o t e , 1977a) o c c u r s and emphasizes t h e ne a r s u r f a c e and o o g e n e t i c n a t u r e o f t h e i n t u r s i o n and N i c o l a v o l c a n i c r o c k s . I n j e c t i o n o f m a g n e t i t e - a p a t i t e m e l t i n t o f r a c t u r e s formed i n t h e now c o n s o l i d a t e d s u r r o u n d i n g i n t r u s i o n o c c u r s s y n c h r o n o u s l y w i t h e r u p t i o n s o f a l k a l i c magma t o t h e s u r f a c e . Such a c t i v i t y m i g ht i n p a r t r e s u l t f r o m i n c r e a s i n g v o l a t i l e p r e s s u r e s . D. AFTON STAGE I n c r e a s i n g v o l a t i l e p r e s s u r e i n an e n c l o s e d v apour b u b b l e formed a t t h e end o f magmatic d i f f e r e n t i a t i o n becomes g r e a t e r t h a n e x t e r n a l l o a d p r e s s u r e and t e n s i l e s t r e n g t h ( N o r t o n and C a t h l e s , 1973) r e s u l t i n g i n e x p l o s i v e emplacement o f C h e r r y Creek b r e c c i a s . I l l Orthomagmatic h y d r o t h e r m a l f l u i d s f o l l o w t h e b r e c c i a and r e s u l t i n copper m i n e r a l i z a t i o n a t A f t o n and e l s e w h e r e . T h i s c opper m i n e r a l i z a t i o n c r o s s c u t s t h e e a r l i e r m a g n e t i t e l o d e s . 6.3.3 D i s c u s s i o n Comparison o f c r o s s - s e c t i o n D (AFTON STAGE: F i g . 6.3) t o t h e s i m p l i f i e d g e o l o g i c a l p l a n o f t h e n o r t h w e s t end o f t h e b a t h o l i t h ( F i g . 6.2) shows r e m a r k a b l e s i m i l a r i t i e s d e s p i t e t h e d i f f e r e n c e s o f p e r s p e c t i v e . The d e f f i c i e n c y o f m a g n e t i t e i n C h e r r y Creek s y e n i t e compared t o Pothook D i o r i t e ( F i g . 6.2; T a b l e 6.2) i s w e l l e x p l a i n e d by d i f f e r e n t i a t i o n o f t h e i m m i s c i b l e i r o n o x i d e s from t h e a l k a l i c magma t h a t c r y s t a l l i z e s t o form t h e C h e r r y Creek u n i t ( F i g . 6.3B). The model a l s o e x p l a i n s t h e c l o s e s p a t i a l a s s o c i a t i o n o f t h e l o d e s w i t h C h e r r y Creek u n i t as w e l l as t h e i r f r e q u e n t o c c u r r e n c e w i t h i n o r n e a r i r o n r i c h P o thook d i o r i t e . F o r m a t i o n o f an i m m i s c i b l e m a g n e t i t e - a p a t i t e l i q u i d a t t h e boundary between d i o r i t i c and a l k a l i c s t a g e s o f d i f f e r e n t i a t i o n m i g h t be a i d e d by t h e i n c r e a s i n g v o l a t i l e c o n t e n t o f t h e magma. A c c o r d i n g t o P h i l p o t t s (1967) h i g h v o l a t i l e c o n t e n t i n magmas p r o b a b l y expands t h e i m m i s c i b i l i t y f i e l d s shown i n F i g . 6.1, t h u s , making i m m i s c i b i l i t y more l i k e l y . The r e l a t i o n s h i p s between m a g n e t i t e - a p a t i t e and co p p e r m i n e r a l i z a t i o n a t A f t o n d e f i n e s s e v e r a l t i m i n g r e l a t i o n s h i p s shown i n t h e model. M a g n e t i t e l o d e s a t A f t o n c o n t a i n m i n o r younger hypogene c o p p e r s u l p h i d e s i n d i c a t i n g t h a t m a g n e t i t e l o d e s were formed b e f o r e a h y d r o t h e r m a l s y s t e m became 112 i m p o r t a n t . E l s e w h e r e i n t h e b a t h o l i t h (sample IM 16; F i g . 2 . 2 ) , m a g n e t i t e o c c u r s as f r a g m e n t s i n a C h e r r y Creek phase i n d i c a t i n g m a g n e t i t e emplacement was n o t t h e l a s t magmatic event t o t a k e p l a c e . An i m p o r t a n t i m p l i c a t i o n from t h e model, r e g a r d i n g t h e r e l a t i o n s h i p between m a g n e t i t e - a p a t i t e and A f t o n , i s t h a t t h e same magma phase was p a r e n t t o b o t h t h e m a g n e t i t e and c opper m i n e r a l i z a t i o n . I n a d d i t i o n t o t h i s c l o s e g e n e t i c r e l a t i o n s h i p , t h e r e i s a l s o b e l i e v e d t o be a s t r u c t u r a l c o n t r o l on b o t h m a g n e t i t e - a p a t i t e emplacement ( S e c t i o n 2.2.6)-and C h e r r y Creek b r e c c i a ( e . g . A f t o n and o t h e r a r e a s around the b a t h o l i t h ) emplacement ( P r e t o , 1968). S i n c e p i c r i t e s appear t o be g e n e t i c a l l y d i s t i n c t f r o m a l k a l i c and d i o r i t i c r o c k s i n t h e b a t h o l i t h , c opper m i n e r a l i z a t i o n t h a t i s s p a t i a l l y and p o s s i b l y g e n e t i c a l l y r e l a t e d t o p i c r i t e , s u c h as I r o n Mask mine, i s n o t g e n e t i c a l l y r e l a t e d t o A f t o n t y p e m i n e r a l i z a t i o n . T h i s c o n c l u s i o n has i m p o r t a n t i m p l i c a t i o n s i n m i n e r a l e x p l o r a t i o n f o r p i c r i t e a s s o c i a t e d d e p o s i t s . Suggested by t h e model f o r i r o n and c opper m i n e r a l i z a t i o n p r e s e n t e d h e r e i s t h a t c o p p e r m i n e r a l i z a t i o n i s p r o duced by l a t e s t a g e magmatic f l u i d s t h a t r e s u l t e d i n f o r m a t i o n o f C h e r r y Creek b r e c c i a s . A magmatic o r i g i n f o r c o p p e r m i n e r a l i z a t i o n i s s u p p o r t e d by H o i l e s (1978) who found " s u l p h u r i s o t o p e a n a l y s e s i l l u s t r a t e t h a t t h e 6 S v a l u e s o f the. A f t o n d e p o s i t a r e c omparably t o o t h e r d e p o s i t s o f magmatic h y d r o t h e r m a l o r i g i n 34 i n d i s p l a y i n g a v a l u e o f p e r m i l 6 S v a l u e c l o s e t o 0 p e r m i l and a < s m a l l s t a n d a r d d e v i a t i o n " . A l k a l i n e t y p e p o r p h y r y d e p o s i t s , such as 113 A f t o n , a r e known t o be s i g n i f i c a n t o n l y i n t h e N o r t h A m e r i c a n c o r d i l l e r a i n t h e r e g i o n f r o m A l a s k a t o Idaho ( H o l l i s t e r , 1978). P o s s i b l y t h e u n i q u e a l t e r a t i o n and m i n e r a l o g y o f a l k a l i c p o r p h y r i e s ( B a r r et_ a l _ . , 1976) i s due t o m i n e r a l i z i n g s o l u t i o n s b e i n g magmatic o r i g i n whereas m i n e r a l i z a t i o n i n c a l c - a l k a l i c p o r p h y r i e s i s due t o c o l l a p s i n g h y d r o -t h e r m a l systems i n v o l v i n g m e t e o r i c and magmatic w a t e r ( T a y l o r , 1974; Whitney, 1975). A major p r o b l e m w i t h t h e i m m i s c i b l e m e l t model i s t h e s t r o n g d e p l e t i o n o f t h e l o d e s i n chromium, and t o a l e s s e r e x t e n t i n t i t a n i u m and vanadium, compared t o d i s s e m i n a t e d m a g n e t i t e i n d i o r i t e o r s y e n i t e . P o s s i b l e e x p l a n a t i o n s f o r t h e d e p l e t i o n m ight be: 1) c o n c e n t r a t i o n o f t h e s e elements i n am p h i b o l e d u r i n g c r y s t a l l i z a t i o n o f t h e l o d e s ; 2) low l i q u i d / l i q u i d d i s t r i b u t i o n c o e f f i c i e n t s between m a g n e t i t e m e l t and s i l i c a t e m e l t f o r t h e s e e l e m e n t s , r e s u l t i n g i n low c o n c e n t r a t i o n s i n t h e i m m i s c i b l e m a g n e t i t e ; o r 3) c o m p l e x i n g o f t h e s e e l e m e n t s w i t h v o l a t i l e s (Ringwood, 1955b). An a l t e r n a t i v e model might be c o n s i d e r e d t o b e t t e r . e x p l a i n t h e d e p l e t i o n o f chromium, t i t a n i u m and vanadium i n m a g n e t i t e and t h e h i g h v o l a t i l e c o n t e n t o f l o d e s (as s u g g e s t e d by t h e l a r g e c r y s t a l s o f a p a t i t e and a m p h i b o l e ) . P o s s i b l y m a g n e t i t e - a p a t i t e i s c o n c e n t r a t e d i n p o c k e t s as a v o l a t i l e r i c h , r e s i d u a l p e g m a t i t i c f l u i d a f t e r c r y s t a l l i z a t i o n o f most o f t h e C h e r r y C r e e k magma. A l t h o u g h c o n c e n t r a t i o n o f m a g n e t i t e -a p a t i t e i n t h i s manner would e x p l a i n g e o c h e m i c a l and t e x t u r a l f e a t u r e s 114 b e t t e r t h a n t h e i m m i s c i b l e m e l t model, t h e r e a r e s e v e r a l i m p o r t a n t f e a t u r e s i t c annot e x p l a i n . These a r e : 1) m a g n e t i t e i s o l d e r t h a n copper m i n e r a l i -z a t i o n a t A f t o n ; n o t s y n g e n e t i c as would be e x p e c t e d by t h i s model; 2) s p a t i a l a s s o c i a t i o n o f m a g n e t i t e - a p a t i t e w i t h b o t h t h e C h e r r y Creek u n i t ( s y e n i t e ) and t h e m a g n e t i t e r i c h Pothook d i o r i t e ; and 3) d e p l e t i o n o f m a g n e t i t e i n C h e r r y Creek r o c k s compared t o Pothook d i o r i t e ( T a b l e 6.2; F i g . 6.2), d e s p i t e e v i d e n c e t h a t t h e magma r e s i d u a l t o P othook d i o r i t e was i r o n r i c h ( T a b l e 6.1). The m a j o r i t y o f e v i d e n c e s t r o n g l y f a v o u r s f o r m a t i o n o f m a g n e t i t e -a p a t i t e l o d e s from an i m m i s c i b l e m e l t r a t h e r t h a n as a r e s i d u a l p e g m a t i t i c f l u i d . 6.4 Summary and C o n c l u s i o n s M a g n e t i t e l o d e s i n t h e I r o n Mask b a t h o l i t h have been examined and two l o d e s mapped i n d e t a i l . E i g h t y - f o u r samples of m a g n e t i t e d i s s e m i n a t e d i n i n t r u s i v e r o c k s and o f m a g n e t i t e i n l o d e s were a n a l y z e d f o r Co,Cr,Cu, Mg,Mn,Ni,Pb,Ti,V, and Zn by a t o m i c 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 . F o u r t e e n samples were a l s o a n a l y z e d f o r major and m i n o r o x i d e s by e l e c t r o n m i c r o p r o b e . S t a t i s t i c a l a n a l y s i s o f g e o c h e m i c a l d a t a i n d i c a t e d m a g n e t i t e from b o t h d i o r i t i c and s y e n i t i c i n t r u s i v e r o c k s i n t h e b a t h o l i t h i s s i m i l a r , whereas m a g n e t i t e i n p i c r i t e s i s u n i q u e l y chromium r i c h . M i n o r element c o n t e n t o f m a g n e t i t e i n l o d e s i s s i m i l a r t o t h a t i n i n t r u s i v e r o c k s e x c e p t f o r a d e p l e t i o n o f chromium, t i t a n i u m and vanadium. Abundance o f 115 m i n o r elements i n l o d e m a g n e t i t e i s a l s o s t a t i s t i c a l l y s i m i l a r t o t h e abundance o f m i n o r e l e m e n t s i n m a g n e t i t e f r o m i r o n d e p o s i t s i n M i s s o u r i , U.S.A. and K i r u n a , Sweden. From t h e s t a t i s t i c a l a n a l y s i s i t was c o n c l u d e d t h a t t h e m a g n e t i t e i n l o d e s was m a g m a t i c - p e g m a t i t i c i n o r i g i n r a t h e r t h a n h y d r o t h e r m a l v e i n o r s k a r n . T h i s m a g n e t i t e - a p a t i t e f l u i d was d e r i v e d from d i o r i t i c o r s y e n i t i c i n t r u s i v e r o c k s . However, t h e m a g n e t i t e -a p a t i t e f l u i d p r o b a b l y s e p a r a t e d a t a l a t e s t a g e i n t h e d i f f e r e n t i a t i o n o f t h e b a t h o l i t h and had c r y s t a l l i z e d a t a l o w e r t e m p e r a t u r e t h a n d i s -s e m i n a t e d m a g n e t i t e . These d i f f e r e n c e s h e l p e x p l a i n t h e l o w e r chromium, t i t a n i u m and vanadium c o n t e n t o f l o d e m a g n e t i t e compared t o d i s s e m i n a t e d m a g n e t i t e . S y n t h e s i s o f f i e l d and g e o c h e m i c a l e v i d e n c e a l l o w s a model t o be d e v e l o p e d f o r t h e o r i g i n o f m a g n e t i t e - a p a t i t e l o d e s i n t h e b a t h o l i t h and a l s o a l l o w s t h e r e l a t i o n s h i p between t h e s e l o d e s and copper m i n e r a l i z a t i o n a t A f t o n t o be d e f i n e d . The i m m i s c i b l e m e l t model, d e v e l o p e d t o e x p l a i n t he g e n e s i s o f m a g n e t i t e l o d e s i n t h e I r o n Mask b a t h o l i t h , depends on t h e magma d i f f e r e n t i a t i n g t o w a r d an e x p e r i m e n t a l l y d e t e r m i n e d m a g n e t i t e - a p a t i t e e u t e c t i c c o m p o s i t i o n ( i . e . 20 t o 35 w e i g h t p e r c e n t a p a t i t e i n t o t a l m a g n e t i t e p l u s a p a t i t e ) . When t h e e u t e c t i c i s r e a c h e d a f t e r c r y s t a l l i z a t i o n o f Pothook d i o r i t e , m a g n e t i t e and a p a t i t e s e p a r a t e t o g e t h e r from t h e s i l i c a t e magma as an i m m i s c i b l e m e l t , and s e t t l e t o t h e base o f t h e magma chamber. L a t e r i n j e c t i o n o f t h e m a g n e t i t e m e l t i n t o s t r u c t u r a l l y weak a r e a s r e s u l t s i n growth o f c r y s t a l s and f o r m a t i o n o f t h e l o d e s . 116 E v i d e n c e s u p p o r t i n g t h e i m m i s c i b l e m e l t t h e o r y i s : 1) e x p e r i m e n t a l e v i d e n c e o f i m m i s c i b i l i t y ; 2) d i f f e r e n t i a t i o n o f m a g n e t i t e and a p a t i t e i n I r o n Mask magma tow a r d a e u t e c t i c c o m p o s i t i o n ; 3) a s s o c i a t i o n o f l o d e s w i t h C h e r r y Creek s y e n i t e and m a g n e t i t e r i c h P o t h o o k d i o r i t e ; and 4) s h a r p drop i n m a g n e t i t e abundance between Pothook d i o r i t e and C h e r r y Creek s y e n i t e . I m p l i c i t i n t h e model p r e s e n t e d i s t h a t m a g n e t i t e - a p a t i t e and c o p p e r m i n e r a l i z a t i o n a t A f t o n a r e c o n s a n g u i n e o u s , b u t n o t c o e v a l because t h e copper m i n e r a l i z a t i o n and C h e r r y Creek b r e c c i a emplacement a r e younger t h a n m a g n e t i t e - a p a t i t e l o d e s a t A f t o n . T h i s i m p l i e s t h a t t h e h y d r o -t h e r m a l s y s t e m was more i m p o r t a n t a f t e r f o r m a t i o n and emplacement of m a g n e t i t e - a p a t i t e l o d e s . G e n e r a l c o n c l u s i o n s r e s u l t i n g f r o m t h e g e o c h e m i c a l i n v e s t i g a t i o n s and model d e s c r i b e d above a r e : 1) C o m p o s i t i o n and minor element c o n t e n t o f m a g n e t i t e i n i g n e o u s r o c k s can be used t o c h a r a c t e r i z e i g n e o u s r o c k s and t o i n d i c a t e t h e i r p e t r o g e n e s i s . F o r example, a s t u d y o f m a g n e t i t e f r o m t h e Tulameen and Copper M o u n t a i n complexes m i g h t s u p p o r t a g e n e t i c l i n k as s u g g e s t e d by F i n d l a y ( 1 9 6 9 ) . 2) Abundance o f m i n o r e l e m e n t s i n m a s s i v e m a g n e t i t e can be used t o i n d i c a t e t h e i r o r i g i n , however, f u r t h e r d a t a i s needed f o r m a g n e t i t e from s k a r n and h y d r o t h e r m a l v e i n d e p o s i t s . 117 3) Ni/Cr r a t i o s show promise as an i n d i c a t o r of magnetite o r i g i n , however, further data i s needed to v a l i d a t e t h e i r use. 4) Magnetite-apatite lodes can commonly be expected to occur i n close proximity to copper m i n e r a l i z a t i o n and, therefore, can be used as a general exploration guide; magnetite-apatite lodes are p a r t i c u l a r l y s i g n i f i c a n t when s p a t i a l l y associated with breccias i n s y e n i t i c terrane. Study of minor element abundances i n magnetite deposits can be used to define the genesis of magnetite-apatite and associated deposits such as some "porphyry type" deposits. Such studies may also be used as a routine aid during p e t r o l o g i c studies. 6.5 Suggestions for Future Research More d e t a i l e d p e t r o l o g i c and geochemical work on the Iron Mask b a t h o l i t h and other s i m i l a r i n t r u s i o n s i s necessary to sharpen the model and the ideas presented here. S p e c i f i c a l l y such research could include: 1) More de t a i l e d sampling of the e n t i r e Iron Mask b a t h o l i t h . Whole rock analyses i n conduction with minor element analysis of magnetite would aid i n i d e n t i f y i n g and c h a r a c t e r i z i n g i n d i v i d u a l phases. Microprobe analysis of i n d i v i d u a l minerals might aid i n explaining the d e f i c i e n c y of lode magnetite i n chromium, titanium and vanadium. Special attention should be paid to magnetite abundance and textures throughout the b a t h o l i t h . 118 2) Similar studies i n other a l k a l i c intrusions containing magnetite lodes such as Copper Mountain and Galore Creek. Such studies should also investigate the use of magnetite lodes as an exploration guide. 3) Major and minor element studies of magnetite from hydro-thermal vein and skarn deposits should be acquired for comparison with magmatic deposits such as Iron Mask lodes. 4) Oxygen isotope studies on magnetite and apatite might help to determine i f the system i s purely magmatic or p a r t l y meteoric, however, lack of experimental data on apatite-water isotope p a r t i t i o n i n g might preclude t h e i r use. A detai l e d understanding of the formation of magnetite-apatite lodes i n the Iron Mask b a t h o l i t h and i n other a l k a l i c intrusions w i l l s i g n i f i c a n t l y aid i n our understanding the petrogenesis of these i n t r u s i v e rocks and t h e i r associated mineral deposits. Such studies might also i n d i c a t e why magnetite-apatite deposits are strongly associated with a l k a l i c rocks. 119 REFERENCES A n g i n o , E.E. and G.K. B i l l i n g s , 1967. Atomic a b s o r p t i o n s p e c t r o m e t r y i n g e o l o g y ; E l s e v i e r , Amsterdam. Badham, J.P.N, and R.D. M o r t o n , 1976. M a g n e t i t e - a p a t i t e i n t r u s i o n s and c a l c - a l k a l i n e magmatism, C a m s e l l R i v e r , N.W.T.; Can. J o u r . E a r t h S c i e n c e , V o l . 13, No. 2, pp. 348-354. B a r r , D.A., P . E . F o x , K.E. N o r t h c a t e and V.A. P r e t o , 1976. The a l k a l i n e s u i t e p o r p h y r y d e p o s i t s — a summary; i n A. 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The i r o n o r e s o f Canada, V o l . 1, B r i t i s h C o l u m b i a and Yukon; G e o l . Surv. Can., Econ. G e o l . S e r i e s , No. 3, pp. 109-128. 126 APPENDIX A SAMPLE SUITE DESCRIPTIONS AND LOCATIONS 127 APPENDIX A SAMPLE SUITE DESCRIPTION Sample t y p e and l o c a t i o n a r e t a b u l a t e d by sample number i n T a b l e A . l . R e f e r e n c e s h o u l d be made t o F i g s . 2.1, 2.2 , 2.3A and 2.3B f o r p l o t t e d sample l o c a t i o n s . 128 TABLE A . l SAMPLE SUITE DESCRIPTION AND SAMPLE LOCATIONS SAMPLE TYPE HOST . LATITUDE LONGITUDE DESCRIPTION OF LOCATION 8 9 10 11 12 13 14 15 I M . 1 IM 10 IM 11 IM 12 IM 13 IM 14 IM 15 IM 16 IM 17 IM 18 IM 19 IM 20 D i s s e m . M a s s i ve M a s s l v e M a s s i v e D i s s e m . D i s s e m . D i s s e m . M a s s l v e M a s s l v e . M a s s l v e D i s s e m . D i s s e m . D i s s e m . M a s s i v e D i s s e m . 1 D i s s e m . V e i n D i s s e m . D i s s e m . Di s s c m . D i s s e m . D i s s e m . D i s s e m . D i s s e m . P o t h o o k P o t h o o k P o t h o o k P o t h o o k P o t h o o k C h e r r y C r e e k P i c r i t e ? P o t h o o k P o t h o o k P o t h o o k P o t h o o k P o t h o o k P i c r i t e C h e r r y C r e e k ? P i c r i t e C h e r r y C r e e k P i c r i t e P o t h o o k P i c r i t e P i c r i t e S u g a r l o a f C h e r r y C r e e k C h e r r y C r e e k ? ^ P i c r i t e » N i c o l a i 5 0 ° 3 9 ' 2 5 " 1 2 0 o 2 9 ' 4 3 " 5 0 ° 3 9 ' 2 4 " 1 2 0 o 2 9 ' 4 6 " 5 0 ° 3 9 ' 2 5 " 5 0 ° 3 9 ' 2 5 " 5 0 ° 3 9 ' 2 5 " 5 0 ° 3 9 ' 2 0 " 1 2 0 ° 2 9 ' 4 9 " 1 2 0 " 2 9 ' 4 9 " 1 2 0 ° 2 9 ' 4 9 " 1 2 0 ° 2 9 ' 3 8 " 5 0 ° 3 8 ' 5 9 " 1 2 0 ° 2 9 ' 2 1 " 5 0 ° 3 9 ' 2 3 " 5 0 ° 3 9 ' 2 2 " 5 0 ° 3 9 ' 3 0 " 1 2 0 ° 2 9 ' 4 3 " 1 2 0 ° 2 9 ' 4 1 " 1 2 0 ° 2 7 ' 5 8 " 5 0 ° 3 9 ' 2 9 " 1 2 0 o 2 7 ' 5 7 " 5 0 ° 3 9 ' 3 r 1 2 0 ° 2 7 ' 5 0 " 5 0 ° 3 9 ' 3 8 " 5 0 ° 3 9 ' 3 5 " 5 0 ° 3 9 ' 2 0 " 1 2 0 ° 2 6 ' 1 0 " 1 2 0 ° 3 0 ' 3 3 " 1 2 0 ° 3 1 ' 1 0 " 5 0 ° 3 9 ' 5 8 " 1 2 0 ° 2 8 ' 0 1 " 5 0 ° 3 9 ' 1 7 " 1 2 0 ° 3 0 ' 0 0 " 5 0 ° 3 9 ' 2 5 " 5 0 ° 3 9 ' 2 2 " 5 0 ° 3 6 ' 3 3 " 5 0 ° 3 6 ' 3 3 " 1 2 0 ° 2 9 ' 4 9 " 1 2 0 ° 2 4 ' 1 2 " 1 2 0 ° 2 4 ' 1 2 " 1 2 0 - 2 3 ' 1 6 " 5 0 ° 4 2 ' 1 8 " 1 2 0 ° 3 6 ' 0 5 " 5 0 ° 3 9 ' 1 2 0 ° 2 8 ' 5 0 ° 3 8 ' 5 3 " 1 2 0 ° 2 3 ' 4 3 " 5 0 ° 3 9 ' 3 4 " 5 0 ° 3 9 , 3 4 " 1 2 0 ° 3 0 ' 4 2 " 1 2 0 - 3 0 ' 4 2 " 5 0 ° 3 9 ' 3 7 " 1 2 0 o 3 0 ' 4 4 " 5 0 0 f t . e a s t o f N P i t , Magnet s h o w i n g b e t w e e n N and S P i t s , Magnet s h o w i n g N P i t , Magnet s h o w i n g M a g n e t s h o w i n g Magnet s h o w i n g 300 f t SE o f S P i t , Magnet s h o w i n g dump f r o m a d i t ESE P o t h o o k L a k e S P i t , Magnet s h o w i n g S P i t , Magnet s h o w i n g 1/2 m i l e S o f C r e s c e n t Zone 1/2 m i l e S o f C r e s c e n t Z o n e 1/2 ml l e S o f C r e s c e n t Zone Norma mi ne dump A f t o n DDI! 7 3 - 3 4 , 6 4 8 f t A f t o n DDII 7 3 - 5 0 , 1 9 1 - 1 9 4 f t 400 f t Nw of C r e s c e n t Zone dump f r o m s h a f t 3 0 0 0 f t SE A f t o n N P i t , Magnet s h o w i n g I r o n Mask m i n e dump dump on A j a x p r o p e r t y dump f r o m a d i t on Wheal Tamar dump f r o m C o p p e r K i n g ml ne N s i d e o f S u g a r l o a f h i l l dump f r o m a d i t n e a r P y t h o n L a k e A f t o n DDH 7 2 - 2 4 , 4 5 5 f t A f t o n DDH 7 2 - 2 4 , 1260 f t A f t o n DDH 7 2 - 8 , 5 3 0 - 5 3 5 f t 1 : I n d i c a t e s m a g n e t i t e i n s a m p l e was n o t a n a l y z e d . 2 ; S a m p l e IM 16 i s d i o r i t i c i n c o m p o s i t i o n , but has been a s s i g n e d t o t h e C h e r r y C r e e k u n i t b e c a u s e o f I t s p o r p h y r i t i c t e x t u r e and l o c a l l y p i n k i s h c a s t of i t s m a t r i x . 129 TABLE A . l c o n t . SAMPLE SUITE DESCRIPTION AND SAMPLE LOCATIONS SAMPLE TYPE HOST LATITUDE LONGITUDE DESCRIPTION OF LOCATION IM 2 1 - 0 IM 21-11 IM 2 2 - 0 IM 2 2 - 1 0 IM 23 IM 24 IM 25 IM 26 IM 27 IM 28 IM 29 IM 30 IM 31 IM 32 IM 33 IM 34 IM 35 IM 36 IM 37 t o t o M a s s l v e M a s s l v e D i s s e m . D i s s e m . D 1 s s e m . D i s s e m . D i s s e m . D i s s e m . D i s s e m . D 1 s s e m . M a s s i v e M a s s l v e M a s s i v e D i s s e m . M a s s l v e P o t h o o k P o t h o o k C h e r r y C r e e k C h e r r y C r e e k C h e r r y C r e e k C h e r r y C r e e k C h e r r y C r e e k 5 0 ° 3 9 ' 2 1 " 5 0 ° 3 9 ' 1 9 " 5 0 ° 3 8 ' 2 2 " 5 0 ° 3 8 ' 4 8 " 5 0 ° 3 9 ' 0 1 " 5 0 ° 3 9 ' 1 0 " 5 0 ° 3 8 ' 5 6 " I r o n Mask H y b r i d 5 0 ° 3 8 ' 5 1 " C h e r r y C r e e k P o t h o o k C h e r r y C r e e k C h e r r y C r e e k C h e r r y C r e e k P i c r i t e C h e r r y C r e e k C h e r r y C r e e k 5 0 ° 3 9 ' 5 1 " 5 0 ° 3 9 ' 3 2 " 5 0 ° 4 3 ' 1 2 M 5 0 ° 3 9 ' 3 7 " 5 0 ° 3 9 ' 3 4 " 5 0 ° 3 9 ' 2 9 " 5 0 ° 5 2 ' 1 7 " 5 0 ° 4 2 ' 18" 5 0 ° 3 9 ' 4 0 " 1 2 0 ° 2 9 ' 4 2 " 120o29'4r' 1 2 0 ° 2 8 ' 4 2 " 1 2 0 ° 2 9 ' 2 0 " 1 2 0 ° 2 9 ' 3 3 " 1 2 0 o 2 9 ' 0 1 " 1 2 0 ° 2 9 ' 0 2 " 1 2 0 ° 2 8 ' 5 5 " 1 2 0 ° 2 8 ' 4 2 " 1 2 0 ° 2 8 ' 1 1 " 1 2 0 ° 3 7 ' 1 3 " 1 2 0 ° 3 0 ' 3 8 " 1 2 0 ° 3 0 ' 3 3 " 1 2 0 ° 3 1 ' 0 5 " 1 2 0 ° 3 0 ' 0 0 " 1 2 0 ° 3 6 ' 0 5 " 1 2 0 ° 3 0 ' 4 0 " C e n t r a l P i t , s h o w i n g M a g n e t S e n d S o u t h P i t , M a g n e t s h o w i ng NW t o e o f S u g a r l o a f H i l l t o p o f r i d g e 1 . 2 km SSE M a g n e t s h o w i n g SE c o r n e r of l a k e , 0 . 5 km SSE M a g n e t s h o w i n g 1 . 3 5 km S o f DM Z o n e ' 1 . 8 0 km o f 0M Z o n e , i n r o a d c u t 1 . 3 km SE o f Magnet s h o w i n g 0 . 4 km ESE o f DM Zone 0 . 2 5 km U N W o f I r o n Cap G l e n I r o n m i n e - C h e r r y B l u f f s A f t o n DUII 7 2 - 1 5 ; a : 164 f t , b : 7 4 0 f t , c : / 4 3 f t , d : 8 1 B f t , e : « 2 9 f t , f : 8 4 5 f t , g : 8 5 5 f t A f t o n DDIl 7 2 - 1 7 ; a : 8 1 f t . b : 1 8 3 0 f t A f t o n DDIl 73-47 ; 1830 f t On W a t c h i n g C r e e k C o p p e r K i n g m i n e A f t o n p i t 130 APPENDIX B SELECTED SAMPLE DESCRIPTIONS AND MODAL ANALYSES 131 APPENDIX B.1 SELECTED POLISHED SECTION DESCRIPTIONS S i x p o l i s h e d s e c t i o n s t h a t have been mentioned i n t h e t e x t o f t h i s t h e s i s a r e d e s c r i b e d i n t h i s s e c t i o n . R e f e r e n c e s h o u l d be made to A p p e n d i x A f o r l o c a t i o n s o f t h e s e specimens. SPECIMEN #4 HAND SPECIMEN -no hand specimen POLISHED SECTION Massive magnetite o c c u r s i n t e r s t i t i a l l y t o a p a t i t e and s i l i c a t e s . S l i g h t d i f f e r e n c e s i n t e x t u r e and c o n c e n t r a t i o n s o f i n c l u s i o n s a l o n g g r a i n boundaries i n d i c a t e a eu h e d r a l e q u i g r a n u l a r t e x t u r e to the o r e . Magnetite g r a i n s average 0.9 mm i n diameter. A n h e d r a l s p i n e l (?) i n c l u s i o n s up to 0.05 mm i n diameter are extremely abundant. Minor m a r t i t i z a t i o n o c c u r s a l o n g f r a c t u r e s and g r a i n b o u n d a r i e s . SPECIMEN #8 HAND SPECIMEN Massive magnetite w i t h minor f i n e e u h e d r a l a p a t i t e . Some l a y e r i n g i s e v i d e n t i n the magnetite w i t h a l t e r n a t e l a y e r s o f dense, stony magnetite and medium g r a i n e d g r a n u l a r magnetite. C o n t a c t s between l a y e r s a r e g e n e r a l l y sharp. V e i n l e t s o f carbonate c u t the magnetite. POLISHED SECTION Euhedral e q u i g r a n u l a r magnetite w i t h g r a i n s 0.1 to 0.2 mm i n diameter. G r a n u l a r i t y i s h i g h l i g h t e d by h a i r l i n e f r a c t u r e s a l o n g g r a i n boundaries and by t r a i n s o f s p i n e l ( i n c l u s i o n s running p a r a l l e l to the g r a i n b o u n d a r i e s . M a r t i t i z a t i o n o c c u r s l o c a l l y a l o n g f r a c t u r e s . SPECIMEN H O HAND SPECIMEN Massive magnetite c o n t a i n i n g p r i s m a t i c a l t e r e d amphibole c r y s t a l s up to 20 mm i n l e n g t h . POLISHED SECTION Massive magnetite t h a t l o c a l l y d i s p l a y s a e u h e d r a l e q u i g r a n u l a r t e x t u r e , ( P l a t e B . l ) . G r a i n s a r e up to 0.5 mm i n diameter. Where etched w i t h HBr the magnetite l o c a l l y shows an extremely f i n e c r y s t a l l o g r a p h i c e x s o l u t i o n t e x t u r e . E x s o l v e d p l a t e s are dark brown to b l a c k i n c o l o u r . C h a l c o p y r i t e o c c u r s as d i s s e m i n a t e d specks. M a r t i t i z a t i o n o c c u r s a l o n g f r a c t u r e s . SPECIMEN IM 15 HAND SPECIMEN Pink b r e c c i a t e d Cherry Creek s y e n i t e t h a t has been h e a l e d by magnetite and l e s s e r c h a l c o p y r i t e . C h a l c o p y r i t e o c c u r s as d i s s e m i n a t i o n s i n the i n t r u s i v e and as s e l v a g e s i n the magnetite v e i n l e t s . POLISHED SECTION Magnetite, c h a l c o p y r i t e and p y r i t e o c c u r as i r r e g u l a r b l e g s i n t e r m i x e d w i t h gangue ( P l a t e B.2). W i t h i n v e i n l e t s c h a l c o p y r i t e o c c u r s as a s e l v a g e and magnetite i—i CO oc c u r s i n the c e n t r e o f v e i n l e t s , s e p a r a t e d from Co c h a l c o p y r i t e by gangue. SPECIMEN IM 3 2C HAND SPECIMEN D r i l l c o r e s e c t i o n o f massive m a g n e t i t e . Magnetite i s c u t by a 5 mm wide v e i n l e t o f ca r b o n a t e . V e i n l e t s o f c h a l c o p y r i t e a l s o c u t the magnetite r u n n i n g s u b p a r a l l e l to the carbonate v e i n l e t . POLISHED SECTION Magne t i t e i n t h i s s e c t i o n d i s p l a y s a prominent c o l l o f o r m t e x t u r e d e f i n e d by banding o f i n c l u s i o n s and r a d i a l f r a c t u r e s . C h a l c o p y r i t e o c c u r s as d i s s e m i n a t e d g r a i n s i n magnetite and s i l i c a t e s , and as v e i n l e t s . SPECIMEN IM 36 HAND SPECIMEN B r e c c i a t e d Cherry Creek s y e n i t e t h a t has been h e a l e d w i t h magnetite. C h a l c o p y r i t e o c c u r s d i s s e m i n a t e d i n magnetite e s p e c i a l l y a l o n g the selvage o f v e i n l e t s . POLISHED SECTION V e i n l e t s c o n s i s t mainly o f c h a p c o p y r i t e and b o r n i t e o c c u r r i n g i n mutual boundary t e x t u r e . B o r n i t e commonly c o n t a i n s c r y s t a l l o g r a p h i c i n t e r g r o w t h s o f c h a l c o p y r i t e ( P l a t e B.3); the bl a d e s o f which a r e o r i e n t e d a p p r o x i m a t e l y 60° to each o t h e r . Magnetite forms e u h e d r a l c r y s t a l s about 0.2 mm i n diameter which a r e surrounded by younger s u l p h i d e s ( P l a t e B.4). 135 APPENDIX B . 2 PETROGRAPHIC DESCRIPTIONS OF  SELECTED SAMPLES Hand specimen and th i n section descriptions are given for eight selected samples; three samples of Cherry Creek unit; three of Pothook unit; and two of P i c r i t e u n i t . The samples were selected because the magnetite i n a l l the samples was analyzed by the electron microprobe, and because they are representative of each unit. SPECIMEN #1  HAND SPECIMEN Medium g r a i n e d , e q u i g r a n u l a r d i o r i t e which on f r e s h s u r f a c e s i s dark grey i n c o l o u r . P o i k i l i t i c hornblende up t o 5 mra i n l e n g t h can be seen e n c l o s i n g f e l d s p a r g r a i n s . The rock i s s t r o n g l y magnetic. THIN SECTION TEXTURES The g e n e r a l t e x t u r e o f t h i s rock i s medium g r a i n e d , H y p i d i o m o r p h i c - g r a n u l a r ( P l a t e B.5). F e l d s p a r i s c o m p l e t e l y s a u s s u r i t i z e d so t h a t o n l y g h o s t s o f g r a i n s can be d i s c e r n e d . G r a i n s t h a t can be observed a r e s u b h e d r a l and appro x i m a t e l y 1 mm i n s i z e . C l i n o p y r o x e n e i s common as equant, subhedral g r a i n s 0.5 to 1 mm i n diameter. P o i k i l i t i c g r a i n s o f hornblende up to 7 mm long e n c l o s e g r a i n s o f f e l d s p a r , pyroxene, a p a t i t e and magnetite. Hornblende i s l o c a l l y a l t e r e d to c h l o r i t e and b i o t i t e . Magnetite forms a n h e d r a l , h i g h l y i r r e g u l a r g r a i n s and g l o b u l e s t h a t a r e i n t e r s t i t i a l to the o t h e r m i n e r a l s . Commonly a s s o c i a t e d w i t h magnetite a r e s u b h e d r a l g r a i n s o f a p a t i t e t h a t form a p p r o x i m a t e l y one p e r c e n t o f the r o c k . HOPE See Table B.2 PARAGENESIS Pyroxene F e l d s p a r Hornblende A p a t i t e — Magnetite l__ —  SPECIMEN #6  HAND SPECIMEN F i n e g r a i n e d p o r p h y r i t i c monzonite w i t h a d i s t i n c t i v e s p e c k l e d appearance due to s c a t t e r e d pyroxene g r a i n s and b i o t i t e f l a k e s . F r e s h s u r f a c e s o f the rock are l i g h t grey t o pink i n c o l o u r . S t a i n e d s u r f a c e s show f i n e p l a g i o c l a s e and pyroxene p h e n o c r y s t s to o ccur i n an o r t h o c l a s e r i c h m a t r i x . THIN SECTION  TEXTURES P l a g i o c l a s e o c c u r s as u n o r i e n t e d , euhedral p h e n o c r y s t s which are g e n e r a l l y 1 mm i n l e n g t h but may be up to 2 mm ( P l a t e B.6). Composition o f p l a g i o c l a s e i s An35_4Q ( a n d e s i n e ) . A l t e r a t i o n o f p l a g i o c l a s e v a r i e s from complete s a u s s u r i t i z a t i o n to being completely f r e s h . O r t h o c l a s e forms the m a t r i x and o c c u r s as ' l a r g e anhedral g r a i n s up to 10 ram i n diameter. Large areas o f o r t h o c l a s e a r e u n a l t e r e d , however, o t h e r a r e a s a r e a l t e r e d to brown, cloudy c l a y ( ? ) . C l i n o p y r o x e n e o c c u r s as euhedral g r a i n s g e n e r a l l y 0.5 mm long. Euhedral l a t h s o f b i o t i t e , l e s s than 1 mm i n l e n g t h o c c u r throughout the s l i d e . Magnetite o c c u r s as d i s s e m i n a t e d , anhedral g r a i n s , 0.1 to 0.5 mm i n s i z e . These g r a i n s show a c l o s e s p a t i a l a s s o c i a t i o n to pyroxene. MODE- See Table B . l PARAGENESIS Pyroxene P l a g i o c l a s e O r t h o c l a s e B i o t i t e Magnetite I  Time -?• SPECIMEN I 12 • HAND SPECIMEN - no hand specimen THIN SECTION  TEXTURES The g e n e r a l t e x t u r e o f the rock i s e q u i g r a n u l a r , medium g r a i n e d h y p i d i o m o r p h i c . F e l d s p a r i s g e n e r a l l y h i g h l y s a u s s u r i t i z e d . Where f r e s h i t i s seen to be equant, weakly l o c k i n g a n h e d r a l p l a g i o c l a s e g r a i n s l e s s than 0.5 mm o c c u r s . Chinopyroxene g r a i n s a r e u n a l t e r e d , stubby, s u b h e d r a l and g e n e r a l l y < 1 mm i n l e n g t h , but o c c a s i o n a l l y up to 3 mm. Magnetite has two modes o f o c c u r e n c e . The f i r s t mode i s as f i n e ( l e s s than 0.1 mm i n diameter) g r a i n s e n c l o s e d by pyroxene. The second mode i s as i r r e g u l a r a n h e d r a l g r a i n s , l e s s than 0.5 mm i n dia m e t e r , o c c u r r i n g i n t e r s t i t i a l l y t o o t h e r m i n e r a l s b u t a d j a c e n t t o pyroxene g r a i n s . A 1 mm wide magnetite v e i n l e t c r o s s e s the t h i n s e c t i o n . Secondary e p i d o t e and b i o t i t e o c c u r i n i r r e g u l a r patches throughout the s e c t i o n . A p a t i t e was not obs e r v e d . MODE- See T a b l e B.2 PARAGENESIS Pyroxene ' F e l d s p a r Magnetite — Time — ^ SPECIMEN # 15 HAND SPECIMEN Green s e r p e n t i n i z e d o l i v i n e p h e n o c r y s t s , up t o 5 mm a c r o s s , o c c u r i n a dark, grey a p h a n i t i c m a t r i x . Rock i s moderately magnetic. THIN SECTION TEXTURES Euhedral phenocrysts o f o l i v i n e and c l i n o p y r o x e n e o c c u r i n a dark, cloudy brown i n d e t e r m i n a n t m a t r i x ( P l a t e B.7) . O l i v i n e i s l a r g e l y a l t e r e d to c l o u d y , brown i d d i n g s i t e ( ? ) . Most o f the o l i v i n e p h enocrysts were p l u c k e d d u r i n g g r i n d i n g . C l i n o p y r o x e n e phenocrysts range i n s i z e from l e s s than 0.1 mm to about 0.5 mm. Magnetite o c c u r s as subhedral g r a n u l e s , l o s s than 0.1 mm i n diameter, d i s s e m i n a t e d i n the m a t r i x . MODE -See Tab l e B.3 ' PARAGENESIS O l i v i n e Pyroxene Magnetite Time SPECIMEN IM 16 HAND SPECIMEN Medium grained, porphyritic d i o r i t e or monzonite, which on fresh surfaces i s medium grey to pink-grey i n colour. Plagioclase phenocrysts are up to 3 mm in length, unaligned and saussuritized. Pyroxene grains occur i n t e r s t i t i a l l y to plagioclase phenocrysts. Surfaces that have been stained show a variable potassium feldspar content i n the matrix. The rock i s moderately magnetic. THIN SECTION TEXTURES Moderately to strongly saussuritized plagioclase occurs as euhedral phenocrysts that vary in length from 1 to 64 mm (Plate D.8). Phenocrysts show a crude trachytic texture and are generally in contact with each other. Clinopyroxene occurs as euhedral grains that are generally less than 1 mm in length. Magnetite forms disseminated, subhedral equant granules. Apatite i s abundant (approximately one volume present) and occurs as euhedral grains up to 0.5 mm across. Spheno and b i o t i t e are minor accessory minerals. MODE -See Table B.l PARAGENESIS Plagioclase Clinopyroxene — Magnetite Apatite ' Time SPECIMEN IM 27  HAND SPECIMEN Fine grained, equigranular monzonite or syenite with a speckled appearance due to scattered fine mafic minerals. On fresh surfaces the rock i s generally pink brown i n colour but i s commonly bleached to a grey-green colour" along microfractures. The rock i s moderately magnetic. THIN SECTION TEXTURES In this section, the rock shows a crowded microporphyritic texture. Phenocrysts of plagioclase are euhedral, approxi-t—» mately 1 mm in length and well saussuritized. Clinopyroxene t^j CO occurs as subhedral to euhedral phenocrysts that are generally less than 0.5 mm in length. P o i k i l i t i c grains of b i o t i t e (after hornblende?), up to 5 mm in length, enclose feldspar and magnetite grains. Magnetite occurs, as subhedral to anhedral disseminated grains that are generally 0.1 to 0.2 mm i n diameter. These grains are generally adjacent to pyroxene grains and partly i n t e r s t i t i a l to plagioclase. Matrix i s altered to brown clay. MODE see Table B.l PARAGENESIS Plagioclase :  Clinopyroxene — Biotite Magnetite SPECIMEN IM 30 HAND SPECIMEN Magnetite r i c h , medium g r a i n e d d i o r i t e . Magnetite v e i n l e t l a c e the rock and i n some areas i n t e r c u m u l u s magnetite shows a p a r t i a l n et t e x t u r e . One c o r n e r o f the specimen shows s t r o n g e p i d o t i z a t i o n . THIN SECTION  TEXTURES P l a g i o c l a s e and c l i n o p y r o x e n e form a cumulate t e x t u r e ( P l a t e B.9). S u b p a r a l l e l p l a g i o c l a s e g r a i n s are euh e d r a l to s u b h e d r a l and g e n e r a l l y a p p r o x i m a t e l y 1 mm i n l e n g t h . S a u s s u r i t i z a t i o n i s moderate to s t r o n g . C l i n o p y r o x e n e o c c u r s as sub h e d r a l g r a i n s g e n e r a l l y 0.5 to 1 mm i n l e n g t h Magnetite o c c u r s as a n h e d r a l i n t e r s t i t i a l g r a i n s l e s s than 0.5 mm a c r o s s . A 0.5 mm wide m i c r o v e i n l e t o f magnetite c r o s s e s the s l i d e . Secondary c h l o r i t e and e p i d a t e o c c u r s l o c a l l y as patches and v e i n l e t s . MODE -See Tab l e B . 2 PARAGENESIS P l a g i o c l a s e C l i n o p y r o x e n e Magnetite Time SPECIMEN IM 35 HAND SPECIMEN Dark b l a c k , sub-rounded, s e r p e n t i n i z e d o l i v i n e p h e n o c r y s t s occur i n an a p h a n i t i c gray m a t r i x . Phenocrysts a r e 2 to 3 mm i n diameter. The rock i s weakly magnetic. THIN SECTION  TEXTURES O l i v i n e o c c u r s as e u h e d r a l , equant p h e n o c r y s t s ( P l a t e B.10). The o l i v i n e has g e n e r a l l y been c o m p l e t e l y s e r p e n t i n i z e d , however, o l i v i n e remains i n the c e n t r e o f some g r a i n s . Only minor secondary magnetite accompanies s e r p e n t i n i z a t i o n . Clinopyroxene o c c u r s as eu h e d r a l c r y s t a l s l e s s than 0.1 mm i n l e n g t h . Chromite o c c u r s as sub h e d r a l g r a i n s , 0.1 to 0 . 2 mm i n diameter, d i s s e m i n a t e d i n o l i v i n e and the m a t r i x . M a t r i x i s a dark, t r a n s l u c e n t , brown-green i s o t r o p i c m a t e r i a l . MODE - see Table B.3 PARAGENESIS O l i v i n e Pyroxene — — -Chromite — Time — ^ 140 P L A T E B . l . G r a n u l a r t e x t u r e i n m a s s i v e m a g n e t i t e ( s a m p l e # 1 0 ) . L e n g t h o f p o l i s h e d s e c t i o n i n p h o t o g r a p h i s 1.5 mm. P L A T E B . 2 . V e i n l e t o f m a g n e t i t e ( d a r k g r e y , p i t t e d ) , p y r i t e ( p a l e y e l l o w ) a n d c h a l c o p y r i t e ( g o l d ) w i t h g a n g u e ( s a m p l e I M 1 5 ) . L e n g t h o f p o l -i s h e d s e c t i o n i n p h o t o g r a p h i s 1.9 mm. PLATE B.3. B o r n i t e ( p i n k - b r o w n ) c o n t a i n i n g e x s o l v e d c h a l c o p y r i t e ( y e l l o w ) ( s a m p l e IM36). L e n g t h o f p o l i s h e d s e c t i o n i n p h o t o g r a p h i s 0.38 mm. PLATE B.4. E u h e d r a l g r a i n s of m a g n e t i t e ( p i t t e d , l i g h t g r e y ) i n m a t r i x o f p y r i t e ( w h i t e ) , b o r n i t e ( p i n k - b r o w n ) and c h a l c o p y r i t e ( g o l d ) (sample IM 3 6 ) . L e n g t h o f p o l i s h e d s e c t i o n i n p h o t o -graph i s 1.9 mm. 142 PLATE B.5. M a g n e t i t e i n t e r s t i t i a l t o f e l d s p a r and c l i n o -p y r o x e n e (good c l e a v a g e ) i n P o t h o o k d i o r i t e . Sample #1 i n p l a n e - p o l a r i z e d l i g h t . L e n g t h o f t h i n s e c t i o n i n p h o t o g r a p h i s 2.4 mm. PLATE B.6. P o r p h y r i t i c C h e r r y C r e e k m o n z o n i t e ( s a m p l e #6: c r o s s e d - n i c h o l s ) . P l a g i o c l a s e and c l i n o p r o x e n e p h e n o c r y s t s o c c u r i n a m a t r i x o f o r t h o c l a s e . L e n g t h o f t h i n s e c t i o n i n p h o t o g r a p h i s 3.1 mm. 143 P L A T E B . 7 . P i c r i t e c o n t a i n i n g a l t e r e d o l i v i n e p h e n o c r y s t s ( l e f t s i d e o f p h o t o g r a p h ) a n d e u h e d r a l c l i n o -p y r o x e n e p h e n o c r y s t s i n a n a p h a n a t i c m a t r i x ( s a m p l e #15: c r o s s e d - n i c h o l s ) . L e n g t h o f t h i n s e c t i o n i n p h o t o g r a p h i s 3.1 mm. P L A T E B . 8 . M e d i u m g r a i n e d p o r p h y r i t i c C h e r r y C r e e k m o n z o -d i o r i t e ( s a m p l e I M 16: c r o s s e d - n i c h o l s ) . P l a g i o c l a s e ( g r e y ) i s w e l l s a u s s u r i t i z e d . C l i n o -p y r o x e n e ( c o l o u r e d ) a n d m a g n e t i t e ( b l a c k ) o c c u r a s e u h e d r a l a n d s u b h e d r a l g r a i n s . L e n g t h o f t h i n s e c t i o n i n p h o t o g r a p h i s 3.1 mm. 144 P L A T E B . 9 . C u m u l a t e p l a g i o c l a s e , c l i n o p y r o x e n e a n d i n t e r -s t i t i a l m a g n e t i t e i n P o t h o o k d i o r i t e ( s a m p l e I M 3 0 : c r o s s e d - n i c h o I s ) . L e n g t h o f t h i n s e c t i o n i n p h o t o g r a p h i s 3.1 mm. P L A T E B . 1 0 . P i c r i t e c o n t a i n i n g e u h e d r a l s e r p e n t i n i z e d o l i v i n e p h e n o c r y s t s a n d e u h e d r a l c l i n o p y r o x e n e c r y s t a l s ( c o l o u r e d ) i n a n i s o t r o p i c m a t r i x ( s a m p l e I M 3 5 : c r o s s e d - n i c h o l s ) . L e n g t h o f t h i n s e c t i o n i n p h o t o g r a p h i s 3.1 mm. 145 APPENDIX B.3 POINT COUNTING TECHNIQUES AND MODES  FOR ROCKS, IRON MASK BATHOLITH, B.C. Modes f o r 25 r o c k specimens were o b t a i n e d by p o i n t c o u n t i n g t h i n s e c t i o n s under a p e t r o g r a p h i c m i c r o s c o p e u s i n g a S w i f t a u t o m a t i c p o i n t c o u n t e r . A p p r o x i m a t e l y 500 co u n t s were done on each s e c t i o n . Modes a r e t a b u l a t e d f o r v a r i o u s r o c k t y p e s i n T a b l e s B . l t o B.4. The r e l i a b i l i t y o f modal e s t i m a t e s i s shown as two s t a n d a r d d e v i a t i o n s . T h i s was c a l c u l a t e d , f o l l o w i n g Chayes ( 1 9 5 6 ) , u s i n g t h e b i n o m i a l d i s t r i b u t i o n f o r nP g r e a t e r t h a n 5 : 2S = 200/ P ( l - P ) where S s t a n d a r d d e v i a t i o n P p r o b a b i l i t y o f t h e o c c u r e n c e o f a m i n e r a l n t o t a l number o f g r a i n s c o u n t e d TABLE B . l CHERRY CREEK U N I T . IRON MASK BATHOLITH, B . C . POINT COUNT DATA FROM THIN SECTIONS MODES: PERCENTAGES t 2S S A M P L E P L A G I O C L A S E O R T H O C L A S E H O R N B L E N D E P Y R O X E N E B I O T I T E M A G N E T ; N o . 6 3 7 t 4 3 5 : 4 0 1 7 i 3 8 ± 2 4 ± 2 I M 1 6 2 ± 4 1 8 ± 3 0 1 4 i 3 0 6 ± 2 I M 15 2 2 i 4 6 4 : 4 0 8 * 3 0 6x2 I M 2 3 1 5 U 5 n . d . 2 0 2 ± 1 t r a c e 0 I M 2 4 l 3 5 ± 4 n . d . 7 i 2 6 t 2 0 2 ± 1 I M 25 - 3 7 ± 4 8 i 2 33±4 1 4 ± 3 8 t 2 I M 26 5 8 i 4 2 7 t 4 2 i l 1 0 l 3 t r a c e 2 ± 1 I M 27 - 7 6 ± 4 t r a c e 1 2 ± 3 6 ± 2 6 * 2 I M 29 59±4 2 7 i 4 0 U i 3 t r a c e 4 ± 2 I M 3 6 3 - 7 5 t 4 0 1 6 ± 3 0 1 0 ± 3 I M 16 5 9 1 4 9 i 3 0 2 3 t 4 0 5 ±2 1 : P a r t i a l m o d a l a n a l y s e s o f p h e o n c r y s t s o n l y . I M 23 c o n t a i n s 47 p e r c e n t m a t r i x and I M 24 c o n t a i n s 50 p e r c e n t m a t r i x . 2 : n . d . means n o t d e t e r m i n e d . 3 : S a m p l e I M 3 6 c o n t a i n s m l c r o v e i n l e t s o f m a g n e t i t e . TABLE B.2 POTHOOK UNIT, IRON MASK BATHOLITH, B . C . : POINT COUNT DATA FROM THIN SECTIONS MODES: PERCENTAGES ± 2S SAMPLE PLAGIOCLASE ORTHOCLASE HORNBLENDE PYROXENE BIOTITE MAGNETITE No. 1 No. 5 No. I I 1 No. 12 IM 30 58±4 55±4 62±4 56±4 9±3 62±4 8±2 1±1 0 t r a c e 0 27 ±4 26±4 25±4 31±4 29 ±4 2±1 5±2 1 ± 1 2±1 0 9±2 6+2 7 ±2 1 1 ± 3 9±2 1: Sample No. 11 a l s o c o n t a i n s 0 . 5 percent q u a r t z . TABLE B.3 PICRITE AND ASSOCIATED ROCKS, IKON MASK BATHOLITH, B . C . :  POINT COUNT DATA FROM THIN SECTIONS MODES: PERCENTAGES ± 2S SAMPLE OLIVINE PHENOCRYSTS HORNBLENDE PYROXENE BIOTITE CHROMITE/ MAGNETITE MATRIX No. 7 No. 1 3 1 No. 15 IM 10 3 IM 13 IM 17A IM 35 21+3 6±2 50±4 0 17±3 26±4 58 ±5 0 0 0 20±4 0 0 0 13±3 16±3 13±3 3±2 4±2 31±4 7±2 7±2 64±4 0 0 0 0 0 15±3 14±3 2±1 t r a c e 7±2 1±1 1±1 44±4 n . d . 2 35±4 7 1 ± 4 71±4 42±5 33±4 1: Sample 13 i s l a r g e l y a l t e r e d t o f i n e - g r a i n e d b i o t i t e . 2: n . d . means not d e t e r m i n e d . 3: Sample IM 10 c o n t a i n s 6 percent f e l d s p a r i n a d d i t i o n to the m i n e r a l s l i s t e d . TABLE B.4 MISCELLANEOUS ROCK TYPES, IRON MASK BATHOLITH, B . C . :  POINT COUNT DATA FROM THIN SECTIONS MODES: PERCENTAGES ± 2S SAMPLE PLAGIOCLASE ORTHOCLASE HORNBLENDE PYROXENE BIOTITE MAGNETITE IM 14 1 _ 72±4 18±3 9±3 1 ± 1 0 IM 2 8 2 23±4 6±2 60±4 0 1 1 ± 3 1: Sample IM 14 i s a hornblende porphyry from S u g a r l o a f u n i t . 2 : Sample IM 28 i s a b r e c c i a t e d p y r o x e n i t e from Iron Mask Hybrid u n i t . 150 A P P E N D I X C SAMPLING METHODS, A N A L Y T I C A L METHODS, AND DATA TABULATION 151 APPENDIX C.1 SAMPLING METHODS At e i g h t o u t c r o p s , two i n d e p e n d e n t samples were t a k e n o f t h e exposed r o c k t y p e (samples A and B; F i g . C . I ) . The second d u p l i c a t e sample (B) was t a k e n w i t h i n a t h r e e metre r a d i u s o f t h e f i r s t sample and was used t o check t h e l o c a l v a r i a b i l i t y o f m i n o r e l e m e n t s i n m a g n e t i t e and, t h u s see how r e p r e s e n t a t i v e one sample was o f an o u t c r o p ( S e c t i o n 4.5; A p p e n d i x C.6). F o l l o w i n g s e p a r a t i o n and c o n c e n t r a t i o n o f m a g n e t i t e from t h e s e samples, e a c h was s p l i t u s i n g a r i f f l e s p l i t t e r i n t o two r e p l i c a t e samples (A' and B') f o r independent a n a l y s i s t o check a n a l y t i c a l p r e c i s i o n . The s a m p l i n g scheme i s shown s c h e m a t i c a l l y i n F i g . C . I . OUTCROP D u p l i c a t e samples A and B t a k e n a t o u t c r o p t o check sample v a r i a n c e . R e p l i c a t e samples A' and B' t o check a n a l y t i c a l p r e c i s i o n . F i g . C.I Sch e m a t i c d i a g r a m o f s a m p l i n g scheme. 152 SAMPLE PREPARATION A number o f methods f o r s e p a r a t i n g m a g n e t i t e were i n i t i a l l y t r i e d b e f o r e t h e methods d e s c r i b e d i n S e c t i o n 4.2 were e v o l v e d . A l l samples were i n i t i a l l y p r e p a r e d by c r u s i n g i n a jaw and cone c r u s h e r and t h e n p u l v e r i z i n g w i t h c e r a m i c p l a t e s u n t i l t h e sample would pass t h r o u g h a 100 mesh n y l o n s i e v e . The f i r s t method, used on samples #1 t o #15, 1M1, 1M10 t o 1M20 ( e x c e p t d u p l i c a t e "B" samples) c o n s i s t e d o f r o u g h u n d e r w a t e r m a g n e t i c s e p a r a t i o n u s i n g a Sepor r e t r a c t a b l e hand magnet f o l l o w e d by m e c h a n i c a l c o n c e n t r a t i o n u s i n g a Superpanner. I f t h e sample was j u d g e d t o be t o o impure (<;95 p e r c e n t m a g n e t i t e ) under a b i n o c u l a r m i c r o s c o p e , c o n c e n t r a t i o n was c o m p l e t e d by a r e p e a t e d c y c l e o f hand g r i n d i n g w i t h c e r a m i c m o r t a r and p e s t l e f o l l o w e d by u n d e r w a t e r m a g n e t i c s e p a r a t i o n . M e c h a n i c a l c o n c e n t r a t i o n u s i n g t h e Superpanner was d i s c o n t i n u e d a f t e r t h e s e samples because i t was e x t r e m e l y s l o w . The r e m a i n i n g samples (3B, 4B, 6B, 9B, 10B, 11B, IM 16B, 1M21 t o 1M37) were c o n c e n t r a t e d i n a d i f f e r e n t manner. M a s s i v e m a g n e t i t e w i t h l i t t l e gangue was c o n c e n t r a t e d by u s i n g a r e p e a t e d c y c l e o f u n d e r w a t e r m a g n e t i c s e p a r a t i o n and g r i n d i n g by hand w i t h c e r a m i c m o r t a r and p e s t l e ( o r by m o t o r i z e d a g a t e m o r t a r ) u n t i l t h e d e s i r e d p u r i t y o f m a g n e t i t e was a t t a i n e d . C o n c e n t r a t i o n was much more d i f f i c u l t , however, f o r d i s s e m i n a t e d m a g n e t i t e and m a s s i v e m a g n e t i t e w i t h abundant grangue. When ground t o o f i n e , g r a i n s o f m a g n e t i t e and gangue tended t o clump t o g e t h e r , due t o weak m a g n e t i c a t t r a c t i o n , making s e p a r a t i o n v i r t u a l l y i m p o s s i b l e . On t h e o t h e r hand, i f ground t o o c o a r s e t o o many m i d d l i n g s o c c u r r e d t h e r e b y 153 d i l u t i n g t h e m a g n e t i t e c o n c e n t r a t e . S e v e r a l methods were t r i e d w i t h o u t s u c c e s s t o overcome t h e p r o b l e m o f c l u m p i n g . These methods and t h e r e s u l t s a r e : Method R e s u l t o r P r o b l e m (1) D i s s o l u t i o n o f gangue u s i n g h y d r o f l u o r i c a c i d (2) Use o f an AC magnet ( H u t t o n , 1950) (3) G r a v i t y s e p a r a t i o n i n C l e r i c i ' s s o l u t i o n (4) Use o f (3) w h i l e s e p a r a t i n g f u n n e l suspended i n an u l t r a s o n i c b a t h (5) Use o f a D i n g s D a v i s Tube D i s s o l u t i o n o f m a g n e t i t e Clumping p e r s i s t e d C lumping p e r s i s t e d Clumping p e r s i s t e d E x t r e m e l y s l o w and poor s e p a r a t i o n A f t e r t h e s e u n s u c c e s s f u l t r i a l s t h e most e f f i c i e n t method found i n v o l v e d t h r e e s t e p s : (1) rough m a g n e t i c s e p a r a t i o n u s i n g an E r i e z L a b o r a t o r y Model (L-8) Wet Drum M a g n e t i c S e p a r a t o r ; (2) d e n s i t y s e p a r a t i o n i n Bromoform ( i f n e c e s s a r y t h i s s t e p was sometimes r e p e a t e d a f t e r g r i n d i n g o f s a m p l e ) ; (3) r e p e a t e d u n d e r w a t e r s e p a r a t i o n w i t h a r e t r a c t a b l e hand magnet a l t e r n a t i n g w i t h g r i n d i n g o f sample w i t h c e r a m i c m o r t a r and p e s t l e u n t i l t h e d e s i r e d p u r i t y was a t t a i n e d . 154 APPENDIX C.2 ANALYTICAL PROCEDURES , Ato m i c A b s o r p t i o n M a g n e t i t e was a n a l y s e d by a t o m i c 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 u s i n g methods m o d i f i e d from Nakagawa (1965; _cf_. Gormasheva e t a l , 1971). R e f e r e n c e s h o u l d be made t o t h i s p a p e r f o r p r o c e d u r e d e t a i l s as o n l y an o u t l i n e o f t h e p r o c e d u r e w i t h m o d i f i c a t i o n s i s g i v e n h e r e . F o l l o w i n g h i s p r o c e d r u e , 1.000 gm of sample was weighed out on a t o p l o a d i n g b a l a n c e and p l a c e d i n a c l e a n b e a k e r . Samples were d i g e s t e d by m o i s t e n i n g w i t h 2 m l d e i o n i z e d w a t e r , a d d i n g 10 ml c o n c e n t r a t e d h y d r o c h l o r i c a c i d and e v a p o r a t i n g t o d r y n e s s u s i n g moderate h e a t . A f t e r a d d i n g 2 ml c o n c e n t r a t e d n i t r i c a c i d t h e sample was a g a i n e v a p o r a t e d t o d r y n e s s . The r e s i d u e was d i g e s t e d u s i n g 1 m l c o n c e n t r a t e d n i t r i c a c i d and 15 m l 6 M c o n c e n t r a t e d h y d r o c h l o r i c a c i d and warming u n t i l d i s s o l v e d . Chromium r i c h p i c r i t e samples and s t a n d a r d SCH-1 p r o v e d d i f f i c u l t t o d i g e s t and, t h e r e f o r e , r e q u i r e d t h e d i g e s t i o n p r o c e d u r e t o be c o n t i n u a l l y r e p e a t e d o v e r a p e r i o d as l o n g as one week. S i l i c a t e i m p u r i t i e s i n samples g e n e r a l l y remained as an i n s o l u b l e r e s i d u e . B l a n k s were made by c a r r y i n g out t h e p r o c e d u r e i n empty b e a k e r s . A f t e r d i g e s t i o n t h e samples were "made up" t o 25 ml i n a v o l u m e t r i c f l a s k u s i n g 6 M h y d r o c h l o r i c a c i d . I r o n was removed from samples and b l a n k s by a d d i n g 0.5 ml of h y d r o -b r o m i c a c i d and e x t r a c t i n g i r o n bromide w i t h MIBK ( m e t h y l i s o b u t y l k e t o n e ) . Three MIBK e x t r a c t i o n s were used on a l l samples. A t t h i s p o i n t t h e 155 p r o c e d u r e used i n t h i s s t u d y d e v i a t e s from t h a t o f Nakagawa. A f t e r t h e MIBK e x t r a c t i o n s t h e aqueous phase was d r a i n e d i n t o a 50 ml v o l u m e t r i c f l a s k ; 6 ml o f ammonium h y d r o x i d e was added and t h e s o l u t i o n was made up t o 50 ml u s i n g d i s t i l l e d w a t e r . The m o l a r i t y o f t h e s o l u t i o n , w i t h r e s p e c t t o H + , was t h e n 1.5 M. E x t r a c t i o n o f m e t a l s i n s o l u t i o n from c a l c i u m as d e s c r i b e d i n Nakagawa was o m i t t e d as i t was f e l t t h e low c o n c e n t r a t i o n s o f c a l c i u m p r e s e n t i n m a g n e t i t e would n o t c a use any s e r i o u s i n t e r f e r e n c e s i n t h e measurement o f e l e m e n t s . S t a n d a r d s were p r e p a r e d f r o m 1000 ugm/ml s t o c k s o l u t i o n s . These s t o c k s o l u t i o n s were p r e p a r e d u s i n g r e a g e n t s and q u a n t i t i e s l i s t e d i n T a b l e C . l made up t o 100 ml u s i n g 6 M h y d r o c h l o r i c a c i d . A combined s t a n d a r d s o l u t i o n was t h e n p r e p a r e d a t a c o n c e n t r a t i o n o f 100pg/ml f o r each element by c o m b i n i n g 10 ml o f each s t o c k s o l u t i o n . A l i q u o t s o f 0.0, 0.25, 0.5, 1.0, 2.0 and 4.0 ml o f t h e combined s t a n d a r d s o l u t i o n was d i l u t e d t o 25 m l i n a v o l u m e t r i c f l a s k u s i n g 1 ml n i t r i c a c i d and 6 M h y d r o c h l o r i c a c i d . Three MIBK e x t r a c t i o n s were t h e n p e r f o r m e d on t h e s t a n d a r d s i n an i d e n t i c a l manner t o t h e m a g n e t i t e samples. A f t e r e x t r a c t i o n s t h e aqueous phase was d r a i n e d i n t o a v o l u m e t r i c f l a s k and made up t o 50 ml u s i n g 6 ml ammonium h y d r o x i d e and d i s t i l l e d w a t e r , t h e r e b y r e s u l t i n g i n s t a n d a r d s o f 0, 0.5, 1.0, 2.0, 4.0 and 8.0 ugm/ml. Because o f e x t r e m e l y poor s e n s i t i v i t y when a n a l y z i n g f o r vanadium i t was n e c e s s a r y t o p r e p a r e s t a n d a r d s o f 10.0, 40.0, 70.0 and 156 TABLE C.1 REAGENTS AND QUANTITY OF REAGENTS  USED IN PREPARING 100 ml OF  1000 ugm/ml STOCK SOLUTIONS ELEMENT Co Cr Cu Mg Mn Pb N i T i V Zn REAGENT USED WEIGHT (1 C o C l 2 " 6 H 0 0.404 K 2 C r 2 0 7 0.283 CuSO, 5H„0 4 2 0.393 MgS0 4 7H 20 1.014 MnSO. 4H.0 4 2. 0.406 P b ( N 0 3 ) 2 0.160 N i C N 0 3 ) 2 6H 20 0.495 K 2 T i 0 C C 2 0 4 ) 2H 20 0.739 N H 4 V 0 3 0.230 ZnSO. 7H o0 4 2 0.440 157 ifJO.O ugm/ml i n a s i m i l a r manner t o t h a t d e s c r i b e d above. A c o m p l e t e s e t o f 1:25 d i l u t i o n s was p r e p a r e d by p i p e t t i n g 1 ml o f sample i n t o a t e s t t u b e and a d d i n g 24 ml o f 1.5 M h y d r o c h l o r i c a c i d . Reagent grade c h e m i c a l s were used t h r o u g h o u t and a l l g l a s s w a r e was washed w i t h d i s t i l l e d w a t e r and d i l u t e h y d r o c h l o r i c a c i d . The a t o m i c a b s o r p t i o n u n i t u s e d , o p e r a t i n g c o n d i t i o n s and d e t e c t i o n l i m i t s a r e shown i n T a b l e C.2. Samples were r u n i n b a t c h e s o f 24; each b a t c h c o n s i s t e d o f 21 samples, two r e p l i c a t e samples from o t h e r b a t c h e s , and one b l a n k . TABLE C.2 ATOMIC ABSORPTION SPECTROPHOTOMETRY OPERATING CONDITIONS AND DETECTION LIMITS SLIT H2 DETECTION ELEMENT INSTRUMENT FLAME WAVELENGTH (&) WIDTH (u rn ) CURRENT (mA) LAMP LIMITS (PPM) Co P-E A i r 2407 25 8 + 5 Cr V-T A i r 3579 100 5 5 Cu V-T A i r 3248 50. 3 3 Mg V-T A i r 2852 50 4 70 Mn V-T A i r 2795 50 5 40 N i P-E A i r 2320 50 8 + 5 Pb P-E A i r 2170 300 6 + 10 T i ^ c o m m e r c i a l a n a l y s i s V V-T N i t r o u s o x i d e 3184 10 20 100 Zn V-T A i r 2138 100 6 3 1: I n s t r u m e n t used: P-E = P e r k i n Elmer model 303; V-T = V a r i o n - T e c h t r o n AA-4, Department o f G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y o f B r i t i s h Columbia. 2: A i r r e f e r s a i r - a c e t y l e n e f u e l m i x t u r e ; N i t r o u s o x i d e r e f e r s t o N i t r o u s o x i d e -a c e t y l e n e f u e l m i x t u r e . 3: D e t e c t i o n l i m i t i s t h e c o n c e n t r a t i o n r e s u l t i n g i n 1 p e r c e n t a b s o r p t i o n . 4: S o l u t i o n s were a n a l y z e d f o r t i t a n i u m by at o m i c a b s o r p t i o n a t Min-En L a b o r a t o r i e s L t d . , N o r t h V a ncouver, B r i t i s h C o l u m b i a . 159 APPENDIX C.3 ANALYTICAL RESULTS Atomic a b s o r p t i o n r e s u l t s a r e l i s t e d i n T a b l e s C.3A and C.3B. A n a l y t i c a l r e s u l t s f o r l o d e m a g n e t i t e a r e i n T a b l e C.3A and r e s u l t s f o r d i s s e m i n a t e d m a g n e t i t e a r e i n T a b l e C.3B. E l e c t r o n m i c r o p r o b e a n a l y s e s o f m a g n e t i t e a r e t a b u l a t e d by sample number i n T a b l e C.4A. M i c r o p r o b e a n a l y s e s o f a p a t i t e i n sample IM 31 a r e t a b u l a t e d i n T a b l e C.4B. R e f e r e n c e s h o u l d be made t o T a b l e A. 1 f o r sample l o c a t i o n s . 160 T a b l e C . 3 A ATOMIC ABSORPTION ANALYTICAL RESULTS FOR LODE MAGNETITE (BY HOST) ( R e s u l t s a r e i n ppm; s e e T a b l e C . 2 f o r d e t e c t i o n l i m i t s ) D i o r i t e h o s t n p l e N o . Co C r Cu Mq Mn NI Pb T1 V Zn 2 79 1 46 2700 300 144 6 2S6 3429 17 3A 97 2 4 9 4 8 0 0 500 166 11 2 1 5 2778 4 2 3 A ' 99 0 48 5 5 0 0 500 170 15 210 2226 31 3B 9 2 2 124 4C00 4 0 0 165 8 245 3321 38 3 B ' 133 0 134 5 2 0 0 4 0 0 3 0 3 0 245 3483 31 4A 95 5 24 5 5 0 0 5 0 0 164 25 160 2735 29 4 A ' 8 6 0 21 5 5 0 0 5 0 0 170 0 240 3013 31 4B 95 0 14 5 8 0 0 400 149 4 135 2670 30 4 B ' 9 8 0 14 6100 4 0 0 160 0 170 2818 23 8 86 7 58 7400 4 0 0 146 3 3 9 5 3147 27 9A 63 1 30 5 3 0 0 4 0 0 133 0 445 2974 52 9 A ' 6 8 1 30 5 2 0 0 4 0 0 159 0 340 3367 31 9B 65 4 26 7200 3 0 0 111 0 575 3082 . 36 9 B ' 61 1 21 7200 300 98 0 6 5 0 3013 29 10A . 165 16 153 2300 1700 100 0 3100 2648 8 6 10A' 155 15 128 2 2 0 0 1600 100 0 4875 3013 6 2 108 90 95 69 4500 1700 120 1 4125 3256 65 10B' 135 98 44 4HO0 1700 137 0 4 2 5 0 3967 45 IM 2 1 - 0 77 5 39 6 5 0 0 4 0 0 8 0 2 475 3483 20 - 1 96 0 12 7000 6 0 0 152 4 740 3298 25 - 2 102 5 21 7900 4 0 0 135 0 265 2833 32 - 3 67 7 44 7800 4 0 0 126 3 275 3483 21 - 4 52 1 78 5400 3 0 0 126 4 460 3104 19 - 5 48 35 141 9 5 0 0 4 0 0 136 0 4 9 0 2818 27 - 6 59 . 1 86 8100 300 123 4 210 2593 27 - 7 61 1 14 6700 300 129' 4 310 2920 22 - 8 61 2 25 7200 4 0 0 120 8 675 2614 27 - 9 69 0 74 7900 3 0 0 9 8 4 340 2 348 23 - 1 0 84 0 52 6 9 0 0 300 106 8 415 2 9 2 0 19 -11 91 1 56 11000 6 0 0 114 6 6 5 0 2777 32 IM 2 2 - 0 86 0 9 3 2 0 0 600 136 12 470 2757 38 - 1 6 8 0 6 5C00 5 0 0 150 13 290 3083 27 - 2 50 0 9 4500 4 0 0 140 0 365 3267 29 - 3 66 0 9 7200 6 0 0 134 1 9 7 5 3 0 4 2 27 - 4 52 0 9 7000 4 0 0 136 3 710 2899 23 - 5 46 27 13 5 9 0 0 3 0 0 137 5 575 2 9 2 0 23 - 6 46 13 9 7200 3 0 0 143 0 600 3430 12 - 7 68 159 18 11200 5 0 0 171 8 5 7 5 3002 23 - 8 107 4 21 8 3 0 0 4 0 0 160 9 240 3471 23 - 9 112 1 14 5700 500 151 0 315 3861 18 - 1 0 107 1 24 7700 400 144 6 340 3861 37 14 2 0 8 1 34 4 0 0 0 1400 270 0 160 2067 248 IM 31A 59 0 5 3400 3 0 0 65 1 255 2397 19 IM 32A 97 5 114 7300 8 0 0 160 0 925 2 5 8 8 77 IM 33A 38 8 13 10500 400 128 5 710 2864 35 IM 37 156 0 34 10900 2 8 0 0 97 0 110 891 424 161 T a b l e C . 3 B ATOMIC ABSORPTION ANALYTICAL RESULTS FOR DISSEMINATED MAGNET IT E (BY HOST) ( R e s u l t s a r e i n ppm; s e e T a b l e C . 2 f o r d e t e c t i o n l i m i t s D i o r i t e h o s t S a m p l e N o . Co C r Cu Mg Mn N1 Pb T1 Zn IB 5 11A U A " 1 IB 1 1 B ' 12 IM 16A IM 16A' IM 16B IM 1 6 8 ' IM 28 IM 30 S y e n i t e h o s t 6A 6 A ' 6B 6 B ' IM 15 IM 23 IM 24 IM 25 IM 26A IM 2 6 A ' IM 26B IM 2 6 B ' IM 27A IM 29 71 110 12 5 6 0 0 700 101 7 60 71 37 10600 1200 70 6 72 152 49 7600 1500 50 7 75 167 45 7400 1600 65 3 35 94 33 9800 1700 63 9 88 98 24 8500 1600 65 3 62 203 28 7100 1300 71 2 50 116 ' 7 8 2300 4 0 0 83 0 54 119 89 2100 4 0 0 54 0 46 133 76 2000 500 67 0 46 130 73 1900 5 0 0 55 0 61 4 0 3 11 5400 4 0 0 129 0 54 44 8 5500 8 0 0 91 16 70 158 63 3500 9 0 0 82 11 72 151 57 3600 700 8 2 10 61 158 21 3800 600 103 0 61 157 21 3900 6 0 0 85 13 58 5 843 10800 9U0 49 2 40 432 108 18100 lino 134 4 14 288 100 4900 3 0 0 130 2 51 231 73 5500 4 0 0 254 3 58 173 24 4 4 0 0 6 0 0 142 0 47 371 20 4000 500 154 6 51 346 24 5400 700 146 0 47 4 8 2 26 6100 8 0 0 188 1 37 121 14 6400 4 0 0 121 0 32 9 6 14 7100 1200 43 0 4750 15% 13.75% 3325 1 9 . 3 8 % 1 3 . 7 5 % 4375 1000 1800 9 6 0 1445 3800 2450 2400 2175 2075 1490 2750 1 2 . B 1 X 700 3400 1430 1375 1255 1550 850 4650 4514 4 0 8 0 3841 4 2 5 0 4341 4773 3321 5597 5166 5620 4696 3501 3501 4623 5574 4601 4124 1742 3500 3SJU2 4349 5 1 9 / 5252 4 8 1 6 4 9 9 3 3861 4031 49 83 72 46 97 54 57 12 25 14 15 33 49 4 9 31 34 27 124 162 17 15 33 38 39 46 25 58 P l c r l t e s and u l t r a b a s l c h o s t 7 13 15 IM 10 IM 12 IM 13 IM 35 39 258 53 1 6 , 0 0 0 5 0 0 58 71 8 9 8 0 9 4 8 3 9 , 9 0 0 9 0 0 594 130 4 . 3 8 % 261 5 4 , 0 0 0 2000 1848 77 1.67% 312 6 4 , 4 0 0 1500 1090 88 2 . 5 3 % 76 4 5 , 8 0 0 2400 1364 115 2 . 2 9 % 3 0 8 4 6 , 4 0 0 2500 1599 139 6 . 1 6 % 496 9 6 , 7 0 0 1500 2210 1 1 3 . 7 5 % 2171 72 8 1090 1194 205 4 4750 906 348 12 1275 9 5 2 362 0 925 1091 248 42 975 906 305 0 2275 1711 302 M i s c e l l a n e o u s V e l n l e t s and d i s s e m i n a t e d 1n d i o r i t e IM 11 S u g a r l o a f U n i t IM 14 N i c o l a a n d e s f t e ( n ) IM 19 E p 1 d o t 1 z e d i n t r u s i v e IM 20 88 10 129 1 0 , 4 0 0 5 0 0 150 1 690 3530 44 24 774 76 3 3 0 0 200 130 0 8 2 5 4923 18 28 1310 62 1 0 , 6 0 0 300 156 7 725 3 8 3 2 44 50 13 137 6 9 0 0 9 0 0 175 6 850 3205 87 1 6 2 TABLE C.4A ELECTRON MICROPROBE ANALYTICAL RESULTS  FOR LODE AND DISSEMINATED MAGNETITE " (Analysis number i s i n brackets following the sample number) OXIDE 1B(3) 1B(if) 1B(5) 1B(6) 6 B ( 1 ) SI02 0.03 0. 15 0.09 0.34 0.23 TI02 2.23 0.39 0.37 0. 35 1.20 AL203 2.27 0.59 1.88 0.53 0.67 CH203 0.04 0.02 0.03 0.03 0.06 V20 3 1.69 1.68 1.42 1.60 1.65 HIO 0.0 0.0 0.0 0.0 0.0 FEO 83.03 84.74 85.42 83.09 87. 14 a NO 0.60 0.11 0.04 0.30 0.39 MGO 0. 14 0.06 0.01 0.08 0.06 CAO 0.04 0.03 0.02 0.01 0.02 BAO 0.0 0.0 0.0 0.0 0.0 NA20 0.0 0.0 0.0 0.0 0.0 K20 0.0 0.0 0.0 0.0 0.0 sun 90.12 87.77 89.28 86.33 91.42 RECALCULATED ON ULVOSPINEL BASIS FEO 33. 11 30.42 31.69 29.89 32.22 FE203 55.49 60.37 59.71 59. 13 61.04 SUM 95.68 93.82 95.27 92.26 97.54 %USP 6.93 1.81 1.47 2.50 4.43 OXIDE 6B(2) 6B(3) 8(1) 8(2) 8(3) SI02 0.06 0. 13 0.20 0.04 0.63 TI02 2.50 0.09 0.05 0.09 0. 11 AL203 0.99 0.10 0.48 0.24 0.67 CB203 0. 18 0.01 0.02 0.03 0.01 V203 1.62 1.50 0.95 1.07 1.01 HIO 0.0 0.0 0.0 0.0 0.0 FEO 85.27 89.77 88.65 75.65 87.47 MHO 0.61 0. 10 0.16 0.08 0. 19 HGO 0.08 0.0 0.50 0.17 0.72 CAO 0.02 0.0 0.01 0.0 0. 14 BAO 0.0 0.0 0.0 0.0 0.0 NA20 0.0 0.0 0.0 0.0 0.0 K20 0.0 0.0 0.0 0.0 0.0 SUM 91.33 91.70 91.02 77.37 90.95 RECALCULATED OH ULVOSPINEL BASIS FEO 33.07 31.23 30. 29 26.06 30.47 FE203 58.02 65.07 64.87 55. 12 63.35 sua 97. 15 98.22 97.52 82.89 97.30 XUSP 7.61 0.77 0.93 0.50 2.78 163 TABLE C.4A cont. OXIDE .8(4) 9A(1) 9A(3) 9A(4) 12(2) SI02 0. 69 2. 90 0. 21 1. 28 0. 08 TI02 0. 10 0. 02 0. 03 0. 16 2. 45 41203 0. 43 0. 38 0. 05 0. 63 3. 79 CB203 0. 04 0. 02 0. 01 0. 03 0. 01 V203 0. 93 0. 93 0. 98 1. 06 1. 29 HIO 0. 0 0. 0 0. 0 0. 0 0. 0 FEO 81. 57 85. 62 87. 27 86. 67 83. 98 HNO 0. 12 0. 04 0. 05 0. 10 . 0. 76 HGO 0. 50 0. 28 0. 0 0. 30 0. 31 CAO 0. 07 0. 10 0. 02 0. 18 0. 0 BAO 0. 0 0. 0 0. 0 0. 0 0. 0 8A20 0. 0 0. 0 0. 0 0. 0 0. 0 K20 0. 0 0. 0 0. 0 0. 0 0. 0 SDH 84. 45 90. 29 88. 62 90. 41 92. 67 RECALCULATED ON ULVOSPINEL BASIS FEO 28. 70 33. 70 30. 09 31. 83 34. 56 FE203 58. 76 57. 70 63. 55 60. 95 54. 92 sua 90. 34 96. 07 94. 99 96. 52 98. 18 SUSP 3. 22 11. 46 0. 94 5. 51 7. 32 OXIDE •12(3) 12(5) 12(6) 15(1). 15(2) SI02 0. 11 0. 10 0.08 0.08 0.07 TI02 0.97 1.73 0.95 2.09 1.38 &L203 1.40 1.06 1.04 7.93 7.35 CB203 0.05 0.05 0.05 4.87 10.21 V203 1.31 1.47 1.38 0. 29 0.23 810 0.0 0.0 0.0 0.0 0.0 FEO 85.59 86.08 87.95 63.33 6 3.97 (ISO 0.53 0.64 0.33 0.28 0.33 HGO 0.02 0.02 0.04 9. 10 8.45 CAO 0.02 0.0 0.02 0.07 0.05 BAO 0.0 0.0 0.0 0.0 0.0 HA20 0.0 0.0 0.0 0.0 0.0 K20 0.0 0.0 0.0 0.0 0.0 SUH 90.00 91. 15 91.84 93.04 92.04 RECALCULATED ON ULVOSPINEL BASIS *EO 31.65 32.43 32.18 25.05 26.27 FE203 59.95 59.62 61.98 48.10 41.90 SDH 96.01 97.13 98.05 97.86 96.24 *0SP 3.33 5.50 3.09 5.75 3.94 164 TABLE C.4A cont. O X I D E 1 5 ( 3 ) IM16(1) IM16(2) IM16(3) IM16B(1) SI02 0.06 0.35 0.14 0. 38 0. 13 1102 1.52 0.29 1.67 0.47 3.19 AL203 7.05 0.41 0.29 0.31 0.03 CB203 9.17 0.02 0.04 0.0 0.09 7203 0.22 1.69 1.72 1.75 1.43 mo 0.0 0.0 0.0 0.0 0.0 FEO 65.77 89.62 89.91 86.36 90.55 HNO 0.29 0.30 0. 16 0. 16 0.10 HGO 8.60 0.22 0.62 0.23 0.04 CAO 0.01 0.0 0.0 0.0 0.06 BAO 0.0 0.0 0.0 0.0 0.0 HA20 0.0 0.0 0.0 0.0 0.0 K20 0.0 0.0 0.0 0.0 0.0 son 92.69 92.90 94.55 89.66 95.62 FEO FE203 SUM XUSP RECALCULATED ON ULVOSPINEL BASIS 25.96 44.25 97. 12 4.25 31.79 64.27 99.34 2. 19 32.74 63. 53 100.92 5.27 30.98 61.55 95.83 2. 93 35.04 61.69 101.80 9.52 O X I D E I M 1 6 B ( 2 ) IM16B'(3) I M 1 6 B U ) IM16B(5) IM21-7(1) SI02 n o 2 AL203 CB203 ?203 NIO FEO HNO a GO CAO BAO NA20 K20 sua 0. 10 0.10 0.13 0. 23 0.26 0.11 1.25 3.55 0. 18 0.04 0.07 0.27 0.03 0.60 0.32 0.01 0.01 0.02 0.02 0.0 1.60 1.74 1.79 1.35 1.21 0.0 0.0 0.0 0.0 0.0 88.08 86.99 85.77 84.56 89.35 0.07 0.06 0.39 0.09 0.07 0.0 0.02 0.05 0. 12 0.26 0.0 0.01 0.01 0.69 0. 19 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 90.04 90.45 91.74 87.84 91.70 FEO FE203 SUM XUSP RECALCULATED ON ULVOSPINEL BASIS 30.70 63.78 96.43 0.73 31.95 61.17 96.58 4. 13 33.90 57.65 97.52 10.99 29.41 61.29 93.98 1.48 30.80 65.07 98.22 1.13 165 TABLE C.4A cont. OXIDE IM21-7(2) IM21-7(3) IM21-7C4) I M 2 5 0 ) IM25(2) SI02 0.48 1.03 1.92 0. 10 0. 10 TI02 0.06 0.02 0.02 5.37 0.25 AL203 0.33 0.50 0.68 0.23 0.29 CB203 0.01 0.0 0.01 0.05 0.08 T203 0.96 0.97 0.84 1.03 2.42 HIO 0.0 0.0 0.0 0.0 0.0 FEO 86.74 88. 13 85.82 89.59 87.96 UNO 0.03 0.07 0.03 0.07 0.03 HGO 0.27 0.47 0.95 0.05 0.0 CAO 0.08 0.12 0. 19 0.0 0.04 BAO 0.0 0.0 0.0 0.0 0.0 HA20 0.0 0.0 0.0 0.0 0.0 K20 0.0 0.0 0.0 0.0 0.0 SOH 88.96 91.31 90.46 96.49 91.17 RECALCULATED ON ULVOSPINEL BASIS FEO 30.27 31.42 31.56 37.26 31.59 FE203 62.76 63.03 60.30 58. 16 62.65 SDH 95.25 97.63 96.50 102.32 97.45 SUSP 2. 11 4.07 7.56 15.45 1.13 OXIDE IM25C3) IM2?A(2) IM27A(4) IM27A(5) I M 3 0 ( 1 ) SI02 0.08 0.15 TI02 0.17 0.03 AL203 0.0 0.16 CH203 0.18 0.01 V203 1.63 1.28 NIO 0.0 0.0 FEO 90.48 87.03 HNO 0.05 0.03 HGO 0.01 0.38 CAO 0.0 2.55 BAO 0.0 0.0 NA20 0.0 0.0 K20 0.0 0.0 SUH 92.60 91.62 RECALCULATED FEO 31.60 27.61 FE203 65.44 66.04 SUH 99.16 98.24 XUSP 0.81 0.67 0.23 0.97 1.79 0.06 0.50 1.64 0.0 0.44 1.24 0.03 0.0 0.01 1.41 1.22 1.34 0.0 0.0 0.0 85.26 79.28 85.39 0.04 0.06 0.47 0.01 1.00 0.05 0.03 2.97 0.01 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 87.07 86.44 91.94 ON ULVOSPINEL BASIS 2 9 . 7 1 2 6 . 0 0 3 4 . 9 2 6 1 . 7 4 5 9 . 2 2 5 6 . 0 9 9 3 . 2 6 9 2 . 3 8 9 7 . 5 6 1 . 1 3 5 . 4 7 1 1 . 7 1 166 TABLE C . 4 A , cont. OXIDE IM30(2) IM30(3) #810-1(1)#810-1(2) #810-1(3) SI02 0.96 0.29 0.83 0.84 0.66 TI02 2.59 2.04 0.01 0.07 0.0 AL203 1.97 2.20 0.60 0.93 0.21 CH203 0.01 0.0 0.0 0.01 0.01 V203 1.06 1.03 0.05 0.0 0.03 HIO 0.0 0.0 0.0 0.0 0.0 FEO 86.32 86.36 89.81 88.13 88.50 HNO 0.60 0-76 0.10 0.36 0. 13 HGO 0.50 0.04 0. 13 0.74 0.09 CAO 0.01 0.01 0.48 0.27 0.24 BAO 0.0 0.0 0.0 0.0 0.0 NA20 0.0 0.0 0.0 0.0 0.0 K20 0.0 0.0 0.0 0.0 0.0 SOH 94.02 92.73 92.01 91.35 89.87 RECALCULATED ON ULVOSPINEL BASIS FEO 34.93 33.84 31.23 30.32 30.37 FE203 57. 11 58.37 65.10 64. 25 64.60 SUM 99.74 98.58 98.54 97.79 96.35 XUSP 10.97 7.00 3.24 3.46 2.62 OXIDE 9A(5) 9A(6) 9A(7) 1B(7) 1B(8) SI02 0. 11 0.40 0.13 0.09 0.15 TI02 0. 10 0.01 0.08 0. 18 0.34 AL203 0.06 0.55 0.21 1.49 0.90 CH203 0.04 0.02 0.0 0.0 0.01 V203 0.99 0.99 0.99 1.60 1.60 HIO 0.0 0.0 0.0 0.0 0.0 FEO 90.73 91.93 93.54 91.41 92.26 HNO 0.05 0. 11 0.06 0.04 0.33 HGO 0.01 0.0 0.01 0.02 0.22 CAO 0.03 0. 01 0.08 0.0 0.0 BAO 0.0 0.0 0.0 0.0 0.0 NA20 0.0 0.0 0.0 0.0 0.0 K20 0.0 0.0 0.0 0.0 0.0 SUM 92. 12 94.02 95. 10 94. 83 95.81 RECALCULATED ON ULVOSPINEL BASIS FEO 31.18 32.37 32. 19 33.20 32.79 FE203 66.19 66. 20 68.19 64.70 66.10 SUM 98.75 100.66 101.93 101.31 102.44 XUSP 0.72 1.55 0.72 0.85 1.51 167 TABLE C.4A cont. OXIDE 1B(9) IH25(4) IM25C5) IM25(6' SI02 0.01 0.09 0.0 0.02 TI02 0. 18 0. 13 0. 11 0.09 AL203 0.0 0.02 0.0 0.01 CB203 0.02 0.06 0.03 0.08 V203 1.60 1.69 1.69 1.69 HIO 0.0 0.0 0.0 0.0 FEO 91.50 92.30 92. 16 91.65 HNO 0.05 0.08 0.04 0.05 HGO 0.0 0.0 0.0 0.0 CAO 0.02 0.0 0.01 0.0 BAO 0.0 0.0 0.0 0.0 NA20 0.0 0.0 0.0 0.0 K20 0.0 0.0 0.0 0.0 SUM 93.38 94.37 94.04 93.59 RECALCULATED ON ULVOSPINEL BASIS FEO 31.71 32. 15 31.91 31.79 FE203 66.45 66.86 66.96 66.53 SUM 100.04 101.07 100.75 100.26 XUSP 0.56 0.71 0.32 0.34 168 TABLE C.4.B j ELECTRON MICROPROBE ANALYTICAL RESULTS FOR LODE APATITE (SAMPLE IM 31) ( R e s u l t s a r e i n w e i g h t p e r c e n t ) OXIDE ANALYSIS 1 2 3 F~ 2.19 2.80 2.00 MgO 0.04 0.04 0.04 P2°5 40.75 40.53 40.58 CI 0.86 0.55 0.98' CaO 56.22 55.91 55.22 MhO 0.09 0.11 0.11 FeO 0.14 0.13 0.14 T o t a l s 100.30 100.07 99.07 OXIDE ANALYSIS Edge o f g r a i n 4 5 C e n t r e o f g r a i n 6 F 2.5 1.83 1.84 MgO 0.04 0.03 0.04 P2°5 40.65 40.99 41.50 CI 1.39 0.46 0.75 CaO 52.96 55.35 57.15 MnO 0.10 0.11 0.13 FeO 0.12 0.12 0.13 T o t a l s '97.76 98.88 101.49 169 APPENDIX C.4' ACCURACY AND PRECISION OF ANALYSES P r e c i s i o n R e p l i c a t e a t o m i c a b s o r p t i o n a n a l y s e s f o r e i g h t d u p l i c a t e d samples (Appendix C . l ) a r e t a b u l a t e d f o r t e n e l e m e n t s i n T a b l e C.5. These 16 r e p l i c a t e a n a l y s e s were used t o d e t e r m i n e a n a l y t i c a l p r e c i s i o n o f a t o o m i c a b s o r p t i o n methods f o l l o w i n g t h e p r o c e d u r e o f Thompson and Howarth (1976) f o r a s m a l l number o f r e p l i c a t e s . U s i n g t h i s method t h e mean o f r e p l i c a t e r e s u l t s v e r s u s t h e d i f f e r e n c e between r e p l i c a t e r e s u l t s a r e p l o t t e d on a l o g - l o g g r a p h i n w h i c h p e r c e n t i l e s f o r t h e a n a l y t i c a l v a r i a n c e a t a p r e d e t e r m i n e d l e v e l o f p r e c i s i o n have been drawn. The p r o b a b i l i t y t h a t x o r more p o i n t s w i l l f a l l above t h e p e r c e n t i l e s f o r a g i v e n l e v e l o f p r e c i s i o n , c a n be q u a n t i f i e d u s i n g b i n o m i a l p r o b a b i l i t y t h e o r y . Formulas f o r t h e c a l c u l a t i o n o f t h e s e p r o b a b i l i t i e s a r e g i v e n i n D i x o n and Massey (1969; T a b l e 20-14). P l o t s o f r e p l i c a t e means v e r s u s r e p l i c a t e d i f f e r e n c e s f o r d a t a i n T a b l e C.5 a r e p r e s e n t e d i n F i g s . C.2-1 t o C.2-10. The n i n e t y and n i n e t y - n i n e p e r c e n t i l e s shown i n t h e f i g u r e s a r e f o r 20 p e r c e n t p r e c i s i o n . P r o b a b i l i t i e s o f 1 o r more p o i n t s o c c u r r i n g above t h e p e r c e n t i l e s a r e g i v e n i n T a b l e C.6. I n g e n e r a l , t h r e e o r more p o i n t s p l o t t i n g above t h e 90 p e r c e n t i l e i n F i g . C.2-1 t o C.2-10 i n d i c a t e s a p r e c i s i o n s e r i o u s l y worse t h a n 20 p e r c e n t . TABLE C.5 SUMMARY OF REELICATE ANALYSES (ATOMIC ABSORPTION) E L E M E N T : CR S A M P L E NUMBER S U F F I X 3 4 6 9 10 11 I M 1 6 I M 2 6 A 2 5 158 1 16 152 116 173 A' 0 0 151 1 15 167 119 371 . B 2 0 158 4 95 94 133 346 B ' 0 0 157 .1 98 98' 130 482 E L E M E N T : CO S A M P L E NUMBER S U F F I X 3 4 6 9 10 1 1 I M 1 6 I M 2 6 A 97 95 70 63 165 72 50 58 A' 99 86 72 68 155 75 54 47 B 92 95 61 65 90 35 46 51 B ' 133 98 61 61 135 88 46 47 E L E M E N T :CU S A M P L E NUMBER S U F F I X 3 4 6 . 9 10 11- I M 1 6 I M 2 6 A 49 24 63 30 153 49 78 20 A' 48 21 57 30 128 45 89 24 B 124 14 21 26 69 33 76 24 B' 134 14 21 21 44 . 24 73 26 171 TABLE C.5 c o n t . E L E M E N T : MG '-S A M P L E NUMBER S U F F I X 3 4 6 9 10 11 IM16 I M 2 6 A 4830 5480 3530 5290 2320 7610 2270 4430 A' 5500' 5520 3600 5210 2170 7380 . 2140 3990 . B 4640 5810 3810 7240 4550 9840 1990 5430 B ' 5210 6140 3850 . 7240 4800 8510 1910 6060 E L E M E N T u M N S A M P L E NUMBER S U F F I X 3 4 6 9 10 1 1 IM 1 6 I M 2 6 A 460 460 880 390 1690 1520 430 580 A' 480 470 720 380 ' 1630 1590 440 520 B 410 380 640 310 1720 1720 470 680 B' 420 380 620 330 1680 1630 470 750 ' E L E M E N T : NI S A M P L E NUMBER S U F F I X 3 4 6 9 10 11 I M 1 6 IM2 6 A x . 166 164 82 133 100 50 83 142 A' 170 170 82 159 100 65 54 154 B 165 149 103 * 111 120 63 67 146 B ' 303 160 85 98 137 65 55 188 172 TABLE C.5 c o n t . E L E M E N T : P B S A M P L E NUMBER S U F F I X 3 4 6 9 10 11 I M 1 6 I M 2 6 A 11 25 11 0 0 7 0 0 A' 15 0 10 0 0 , 3 0 6 . B 8 4 0 0 1 9 0 0 B * 0 0 13 0 0 3 0 1 E L E M E N T S A M P L E NUMBER S U F F I X 3 4 6 9 10 1 1 I M 1 6 I M 2 6 A 215 160 2400 445 3100 13.75% 1000 1430 A' 210 240 2175 340 4875 3325 1800 1375 B 245 135 2075 575 4125 19.38% 960 1255 B' 245 170 1490 650 4250 13.75% 1445 1550 E L E M E N T : V S A M P L E NUMBER S U F F I X 3 4 6 9 10 11 I M 1 6 I M 2 6 A 2778 2735 4623 2974 2648 3841 5597 5197 A' 2226 3013 5574 3367 3013 4250 5166 5252 B 3321 2670 4601 3082 3256 4341 5620 4816 B ' 3483 2818 4124 3013 3967 4773 4696 4993 173 TABLE C.5 c o n t . E L E M E N T : ZN . S A M P L E NUMBER S U F F I X 3 i 4 6 9 10 11 , IM16: IM26 A 42 29 49 52 86 72 12 33 A' 31 31 31 31 62 46 25 38 B 38 30 34 36 65 97 14 39 B' 31 23 27 29 45 - 54 15 46 174 lOOOr 3 3 ' 7 'l '• / / 1 Pi / / / / — 0 / / / 9 g 7 g / / / j / / ^ * / / j n / / / * y 8 : — — ^ / / / / o 9 g 7 H 7 • / / / p| / / / / / / \ j o / / • * / —: - O O ^ J 1 / / / / — © — © 1 2 3 4 5 6 7 8 910 2 3 4 5 6 7 8 9 1 0 0 2 3 4 5 6 7 8 91000 Mean of Duplicate Results (ppm) Pig. C.2-1. Chromium : 20$ precision, 175 F i g . C.2-2. C o b a l t : 2 0 % p r e c i s i o n . 176 100 9 8 7 6 5 A e c 3 » a) OS e v a I v m 01 o c u 01 10 9 8 7 .6 5 4 / / 1 / / / / / / / / O / / / / /. / / / / / / / / 0 Q V \ / / / / / f / / X. 1 / / y / —G 9~ / —o n 9 4= 1 n Mean o f D u p l i c a t e R e s u l t s (ppm) F i g . C . 2 - 3 . C o p p e r : 2 0 % p r e c i s i o n . 177 / / o / / / A-/ O / / / / / —.—i / / ! / —; < i — ) / / / / c ) / ' 7 / / / —^  / / / / / / / / / / Mean o f D u p l i c a t e R e s u l t s (ppm) F i g . C.2-4. Lead :20% p r e c i s i o n . 178 e o. a a) u / — .HI-- V / / ^ / / / ° o / c I / / o / / _Z_ c 1 o o o o 1 o o e-O.OOfl Mean of Duplicate Results (ppm) F i g . C.2-5. M a g n e s i u m : 2 0 % p r e c i s i o n . 179 0 . 0 0 1 I I I n U I I I I I I I I 1 I I I I 1 I 0 . 0 1 2 3 4 5 6 7 8 9 0 . 1 2 3 4 5 6 7 8 9 1 Mean of Duplicate Results (ppm) F i g . C.2-6. Manganese : 20% p r e c i s i o n 180:? F i g . C.2.-7. N i c k e l : 20% p r e c i s i o n . 181 1000 E-a a - * a u ^ 3 cn ai Pi c 41-2 01 ca 01 o c 01 u 7~ e y-/ / / / f <* / / / / / " o / / ) / / / / 0 f / r < / / / / o / / / / / « , Mean of Duplicate Results (ppm) F i g . C . 2 - 8 . T i t a n i u m : 20% p r e c i s i o n . 182) J / 0 i / > / / / / ^ --V / O o o / ' ji. O / 0 O o c o 1000 2 3 4 5 6 7 8 9.10000 2 3 4 5 6 7 8 9 Mean of Duplicate Results (ppm) F i g . C . 2 - 9 . V a n a d i u m : 2 0 % p r e c i s i o n . 183 F i g . C.2-10. Z i n c : 20% p r e c i s i o n . 184 TABLE C.6 PROBABILITIES ASSOCIATED WITH PERCENTILE POINTS ABOVE PERCENTILE (x) DATA OF FIG. C.2 CUMULATIVE' PROBABILITY OF x OR GREATER POINTS OCCURRING ABOVE PERCENTILE 90 90 90 90 99 99 99 99 1 2 3 4 1 2 3 4 0.815 0.486 0.211 0.069 0. 148 0.011 0.001 0 A c c u r a c y A q u a l i t a t i v e assessment o f t h e a c c u r a c y o f a t o m i c a b s o r p t i o n a n a l y s e s was g a i n e d by a n a l y s i n g a h e m a t i t e o r e s t a n d a r d (SCH-1; S t e g e r e t a l . , 1975) and a Japanese m a g n e t i t e o r e s t a n d a r d (#810-1) made by t h e Yawata I r o n and S t e e l Co., L t d . i n March, 1967 from Texada s k a r n m a g n e t i t e . D i g e s t i o n and a n a l y t i c a l p r o c e d u r e s used were t h e same d e s c r i b e d f o r m a g n e t i t e samples i n A p p e n d i x C . l . R e s u l t s o f s t a n d a r d m a t e r i a l a n a l y s i s a r e g i v e n i n T a b l e C.7. S t a n d a r d #810-1 p r o b a b l y g i v e s t h e b e s t i n d i c a t i o n o f a c c u r a c y o f d a t a as i t i s most s i m i l a r t o samples i n t h i s s t u d y . Copper and magnesium g i v e good a c c u r a c y , however, d i f f e r e n c e s e x i s t f o r o t h e r elements between v a l u e s r e p o r t e d i n t h i s s t u d y and recommended v a l u e s . A c c u r a c y a p p ears t o be adequate f o r t h e p u r p o s e s o f t h i s s t u d y . 185 TABLE C.7 ATOMIC ABSORPTION ANALYSES OF STANDARD IRON ORES STANDARD SCH-1 ELEMENT  REMARKS Co Cr Cu Mg Mn Mi Pb TI V Zn Recommended o r - 20(P) 9(P) 200 7770 - - 310 43(P) -p r o v i s i o n a l v a l u e (P) V a l u e s found i n - 12 9 130 " 4T8U - " - 9TJ TGJ " -t h i s s t u d y - 10 10 120 4590 - 185 0 -f r o m f o u r r e p l - - 12 10 130 4510 - 165 43 -i c a t e samples - 8 6 100 4200 - 145 0 -A r i t h m e t i c mean - 11 9 120 4570 146 52 STANDARD #810-1 ELEMENT REMARKS Co Cr Cu Mg Mn N i Pb T i V Zn Recommended - _ 460 6700 1500 300 v a l u e ^ V a l u e s found i n - "4T5" ~6"14"0~ '"ff9"<r — ~Z0~5 -- -t h i s s t u d y - - 514 6870 930 - - 210 - -from f o u r r e p l - - - 468 6530 980 - 200 - -i c a t e samples - 455 6060 930 - 240 - -A r i t h m e t i c mean - _ 471 6400 930 214 1 : Element n o t d e t e r m i n e d i n s t a n d a r d m a t e r i a l . 186 APPENDIX C.5 ANALYSIS OF VARIANCE The h i e r a r c h i c a l s a m p l i n g p l a n used f o r e i g h t samples i n t h i s s t u d y (Appendix C . l ) a l l o w s t h e t o t a l v a r i a t i o n i n a s e t o f d a t a t o be b r o k e n down and a s s i g n e d t o v a r i o u s s o u r c e s by u s i n g an a n a l y s i s o f v a r i a n c e w i t h two l e v e l s o f s u b d i v i s i o n ( G r i f f i t h , 1967, p. 371). U s i n g t h e s a m p l i n g p l a n d e s c r i b e d i n A p p e n d i x C . l d a t a v a r i a b i l i t y can be d i v i d e d i n t o : ':'/(!) v a r i a b i l i t y between o u t c r o p s ( u n i t v a r i a b i l i t y ) ; ( i i ) v a r i a b i l i t y w i t h i n o u t c r o p s (sample v a r i a b i l i t y ) ; and ( i i i ) v a r i a b i l i t y due t o sample p r e p a r a t i o n and a n a l y t i c a l t e c h n i q u e s . D e t e r m i n a t i o n o f t h e v a r i o u s s o u r c e s o f d a t a v a r i a t i o n i s i m p o r t a n t s i n c e t o c h a r a c t e r i z e u n i t s o f t h e I r o n Mask b a t h o l i t h by t h e minor element c o n t e n t of m a g n e t i t e from d i s c r e t e o u t c r o p samples, s o u r c e s ( i i ) and ( i i i ) above s h o u l d be s i g n i f i c a n t l y l e s s t h a n ( I ) . I f ( i i ) and ( i i i ) a r e g r e a t e r t h a n ( i ) , t r u e v a r i a b i l i t y o f d a t a w i t h i n a u n i t w i l l be masked by s a m p l i n g and a n a l y t i c a l " n o i s e " . B a s i c e q u a t i o n s used i n t h i s a n a l y s i s a r e g i v e n i n G r i f f i t h s (1967, p. 3 7 5 ). T e s t s were p e r f o r m e d on a r i t h m e t i c a t o m i c a b s o r p t i o n d a t a f o r a l l e l e m e n t s e x c e p t t i t a n i u m and chromium. A l o g a r i t h m i c t r a n s f o r m was used f o r t h e s e e l e m e n t s as t h e i r abundance spanned s e v e r a l o r d e r s o f magnitude. R e s u l t s a r e t a b u l a t e d by element i n T a b l e C.S f r o m d a t a g i v e n i n T a b l e C.5. C a l c u l a t e d F v a l u e s a r e g i v e n as w e l l as a c t u a l F 187 v a l u e s f o r a = 0.05 and 0.01. .C o n c l u s i o n s b a s e d :.on t h e s e ,F v a l u e s . a r e g i v e n b e l o w each t a b l e . F o l l o w i n g G r i f f i t h s (1967, p. 377) p o i n t e s t i m a t e s o f t h e amount o f d a t a v a r i a n c e f r o m each s o u r c e can be made a r e g i v e n i n T a b l e C.9V--, These e s t i m a t e s a l l o w t h e magnitude o f v a r i a n c e s from v a r i o u s s o u r c e s t o be more r e a d i l y v i s u a l i z e d and compared. E x a m i n a t i o n o f T a b l e s C.8 and C.9> ;shows t h a t c o p p e r and l e a d have s a m p l i n g v a r i a n c e s and a n a l y t i c a l and sample p r e p a r a t i o n v a r i a n c e s s i g n i f i c a n t l y g r e a t e r t h a n v a r i a t i o n between o u t c r o p s . F o r t h i s r e a s o n c o p p e r and l e a d were no t used i n c h a r a c t e r i z i n g m a g n e t i t e i n t h e I r o n Mask b a t h o l i t h . 188 TABLE C.:8 NESTED ANALYSIS OF VARIANCE ELEMENT : LOG CR Source of V a r i a t i o n d.f. Sum of Squares Mean Square F F 0.05 F 0.01 Among outcrops 7 40.982 5.855 9.490 3.50 6.18 Among samples (sampling error) 8 4.932 0.61,7 2.917 2.59 3.89 Among r e p l i c a t e s ( a n a l y t i c a l error) 16 3.384 0.212 Concl.: V a r i a t i o n among outcrop means v a r i a t i o n among sample means. Var i a t i o n among sample means v a r i a t i o n among r e p l i c a t e s . ELEMENT : CO Source of V a r i a t i o n d.f. Sum of Squares Mean Square F F 0.05 F 0.01 Among outcrops 7 25,574.875 3,653.554. 10.44 3.50 6.18 Among samples Q 2,801.000 350.125 (sampling error) O Among r e p l i c a t e s ( a n a l y t i c a l error) 16 3,458.000 216.125 1.620 2.59 3.89 Concl.: V a r i a t i o n among outcrop means v a r i a t i o n among sample means. Var i a t i o n among sample means v a r i a t i o n among'replicates. 189 TABLE ,C.8, c o n t . E L E M E N T : C U So u r c e o f V a r i a t i o n d . f . Sum o f Squares Mean Square F F 0.05 F 0.01 Among o u t c r o p s 7 28,659.500 4,094.214 2.099 3.50 6.18 Among samples ( s a m p l i n g e r r o r ) 15,604.000 8 1,950.500 Among r e p l i c a t e s ( a n a l y t i c a l e r r o r ) 16 834.000 52.125 37.42 2.59 3.89 C o n c l . : V a r i a t i o n among o u t c r o p means v a r i a t i o n among sample means. V a r i a t i o n among samples v a r i a t i o n among r e p l i c a t e s . E L E M E N T : MG So u r c e o f V a r i a t i o n d . f . Sum o f Squares Mean Square F F 0.05 F 0.01 Among o u t c r o p s 7 1.032 0.147 7.577 3.50 6.18 Among samples 8 0.155 0.0194 ( s a m p l i n g e r r o r ) Among r e p l i c a t e s ( a n a l y t i c a l e r r o r ) 16 0.017 0.0011 17.64 2.59 3.89 C o n c l . : V a r i a t i o n among o u t c r o p means v a r i a t i o n among sample means. V a r i a t i o n among samples v a r i a t i o n among r e p l i c a t e s . 190 TABLE C.8 c o n t . E L E M E N T : MN S o u r c e o f V a r i a t i o n d . f . Sum o f Squares Mean Square F F 0.05 F 0.01 Among o u t c r o p s 7 0.0826 0.0118 11.83 3.50 6.18 Among samples ( s a m p l i n g e r r o r ) 8 0.00085 0.0011 56.38 2.59 3.89 Among r e p l i c a t e s ( a n a l y t i c a l e r r o r ) 16 0.0003 0.000019 C o n c l . : V a r i a t i o n among o u t c r o p means v a r i a t i o n among samples. V a r i a t i o n among samples v a r i a t i o n among r e p l i c a t e s . E L E M E N T : NI S o u r c e o f V a r i a t i o n d . f . ' Sum o f Squares Mean Square F F 0.05 F 0.01 Among o u t c r o p s 7 69,027.219 9,861.031 10.31 3.50 6.18 Among samples ( s a m p l i n g e r r o r ) 8 7,650.250 956.281 1.286 2.59 3.89 Among r e p l i c a t e s ( a n a l y t i c a l e r r o r ) 16 11,898.500 743.656 C o n c l . : V a r i a t i o n among o u t c r o p means v a r i a t i o n among samples. V a r i a t i o n among samples v a r i a t i o n among r e p l i c a t e s . 191 TABLE C.8 c o n t . E L E M E N T : PB S o u r c e o f V a r i a t i o n d . f . Sum o f Squares Mean Square F F 0.05 F 0.01 Among o u t c r o p s 7 417.719 59.674 2.223 3.50 6.18 Among samples ( s a m p l i n g e r r o r ) 8 214.719 26.840 1.142 2.59 3.89 Among r e p l i c a t e s ( a n a l y t i c a l e r r o r ) 16 490.500 30.656 C o n c l . : V a r i a t i o n among o u t c r o p means v a r i a t i o n among sample means. V a r i a t i o n among sample means v a r i a t i o n among r e p l i c a t e s . E L E M E N T : LOG TI S o u r c e o f V a r i a t i o n d.f.' Sum o f Squares Mean Square F F 0.05 F 0.01 Among o u t c r o p s 7 18.150 2.593 24.23 3.50 6.18 Among samples ( s a m p l i n g e r r o r ) 8 0.852 0.107 1.197 2.59 3.89 Among r e p l i c a t e s ( a n a l y t i c a l e r r o r ) 16 1.430 0.0894 C o n c l . : V a r i a t i o n among o u t c r o p means v a r i a t i o n among sample means. V a r i a t i o n among sample means v a r i a t i o n among r e p l i c a t e s . 192 TABLE C.8 c o n t . E L E M E N T : v S o u r c e o f V a r i a t i o n d . f . Sum o f Squares Mean Square F F 0.05 F 0.01 Among o u t c r o p s • 7 29,001,832.1 4,143,118.871 13.77 3.50 6.18 Among samples ( s a m p l i n g e r r o r ) 2,407,670.500 8 300,958.813 Among r e p l i c a t e s ( a n a l y t i c a l e r r o r ) 16 2,085,861.000 130,366.313 2.309 2.59 3.89 C o n c l . : V a r i a t i o n among o u t c r o p means v a r i a t i o n among sample means. V a r i a t i o n among sample means v a r i a t i o n among r e p l i c a t e s . E L E M E N T : ZN S o u r c e o f V a r i a t i o n d . f . Sum o f Squa r e s Mean Square F F 0.05 F 0.01 Among o u t c r o p s 7 8,338.469 1,191.210 10.76 3.50 6.18 Among samples 8 885.750 ( s a m p l i n g e r r o r ) 110.719 Among r e p l i c a t e s ( a n a l y t i c a l e r r o r ) 16 2,415.500 150.969 1.364 2.59 3.89 C o n c l . : V a r i a t i o n among o u t c r o p means v a r i a t i o n among sample means. V a r i a t i o n among sample means v a r i a t i o n among r e p l i c a t e s . 193 '.:. . . TABLE ,C. 9 ... POINT ESTIMATES OF VARIANCE FROM DIFFERENT SAMPLING LEVELS ELEMENT: LOG CR S o u r c e o f V a r i a t i o n V a r i a n c e O u t c r o p means ;•: ' 1.310 Sample means 0.203 R e p l i c a t e s 0.2115 ELEMENT: CO S o u r c e o f V a r i a t i o n V a r i a n c e O u t c r o p means 825.857 Sample means 67.000 R e p l i c a t e s 216.125 ELEMENT: CU S o u r c e o f V a r i a t i o n V a r i a n c e O u t c r o p means 535.929 Sample means 949.188 R e p l i c a t e s 52.125 194 TABLE C.9 c o n t . ELEMENT: MG S o u r c e o f V a r i a t i o n V a r i a n c e O u t c r o p means 0.0319 Sample means 0.0092 R e p l i c a t e s 0.0011 ELEMENT: MN S o u r c e o f V a r i a t i o n V a r i a n c e O u t c r o p means Sample means R e p l i c a t e s 0.0027 0.0005 0.00002 ELEMENT: >NI, S o u r c e o f V a r i a t i o n V a r i a n c e O u t c r o p means Sample means R e p l i c a t e s 2226.188 106.313 74 3-.6 56 195 TABLE C. .97 c o n t . ELEMENT: PB S o u r c e o f V a r i a t i o n V a r i a n c e O u t c r o p means 8.209 Sample means 1.908 R e p l i c a t e s 30.656 ELEMENT: LOG TI So u r c e o f V a r i a t i o n V a r i a n c e O u t c r o p means Sample means R e p l i c a t e s 0.622 0.0088 0.0894 ELEMENT: V S o u r c e o f V a r i a t i o n V a r i a n c e O u t c r o p means Sample means R e p l i c a t e s 960,540.0145 82,296.250 130,366.313 1 196 TABLE C.19J cont. ELEMENT: ZN / Source of V a r i a t i o n Variance Outcrop means Sample means Replicates 270.123 20-125 150.969 

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