Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The contact metasomatic magnetite deposits of southwestern British Columbia Sangster, David Frederick 1964

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1964_A1 S33.pdf [ 20.77MB ]
Metadata
JSON: 831-1.0053070.json
JSON-LD: 831-1.0053070-ld.json
RDF/XML (Pretty): 831-1.0053070-rdf.xml
RDF/JSON: 831-1.0053070-rdf.json
Turtle: 831-1.0053070-turtle.txt
N-Triples: 831-1.0053070-rdf-ntriples.txt
Original Record: 831-1.0053070-source.json
Full Text
831-1.0053070-fulltext.txt
Citation
831-1.0053070.ris

Full Text

THE CONTACT METASOMATIC M A G N E T I T E D E P O S I T S OF SOUTHWESTERN B R I T I S H C O L U M B I A b y DONALD F R E D E R I C K SANGSTER M . S c , M c G i l l U n i v e r s i t y , 1961 A T H E S I S SUBMITTED I N P A R T I A L F U L F I L M E N T OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF P H I L O S O P H Y i n t h e D e p a r t m e n t o f G e o l o g y We a c c e p t t h i s t h e s i s a s 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 T H E U N I V E R S I T Y OF B R I T I S H C O L U M B I A M a y , I96I4.. In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study« I f u r t h e r agree that per-m i s s i o n f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . I t i s understood that, copying or p u b l i -c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n p e r m i s s i o n . Department of (j6T0£QG^' The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8, Canada Date The University of B r i t i s h Columbia FACULTY OF GRADUATE STUDIES PROGRAMME OF THE FINAL ORAL EXAMINATION FOR THE DEGREE OF DOCTOR OF PHILOSOPHY B„Sc. (Chemistry). Bishop's University, 1955 B.Sc (Geology), M c G i l l University, 1958 M.Sc, McGill University, 1961 WEDNESDAY, ' SEPTEMBER -2-3/-1-9-64, AT Is30 P.M. IN ROOM 102, FORESTRY AND GEOLOGY BUILDING of DONALD FREDERICK SANGSTER COMMITTEE IN CHARGE Chairman: I.McT. Cowan L.G.R. Crouch K.C. McTaggart J.V. Ross W.F. Slawson R.M. Thompson W.H. White External Examiner: H. B. D. Wilson University of Manitoba Department o f Geology THE CONTACT METASQMATIG MAGNETITE DEPOSITS OF SOUTHWESTERN BRITISH COLUMBIA ABSTRACT Ore zones s skarn g host rocks, and associated intrusions of 12 magnetite deposits war® studied i n both f i e l d and laboratory to determine t h e i r mineralogica.1 and geochemical c h a r a c t e r i s t i c s s o r i g i n of the i r o n , and factors c o n t r o l l i n g emplacement of iron-bearing minerals. This study seeks a better understanding of; the o r i g i n and mode of occurrence of contact metasomatic magnetite deposits which i n tarn may provide better guides to t h e i r exploration and evaluation. Local folds and f a u l t s are important factors in the explacement of magnetite iri v olcanic rocks and limestone of the Vancouver group,. Adjacent stocks are of intermediate composition. Post-ore l e u c o d i o r i t e dykes are common i n many orebodi.es . The author proposes that the process by which skarn i s formed be c a l l e d s k a r n i f i c a t i o n i . e . the replacement by;, conversion i n t o , or introduction of skarn. The term would include a l l processes by which, skarn may be formed such as contact metamorphism, contact metasomatism s or regional metamorphism. Skarn i n the coastal. B r i t i s h Columbia, region i s composed mainly of garnet (an d r a d i t e - g r o s s u l a r i t e ) , pyroxene (diopside-hedenbergite) s epidote s and magnetite. Conformity to Gibbs Phase Rule and the non-appearance of incompatible phases i s strong evidence that equilibrium was attained during s k a r n i f i c a t i o n . Magnetite i s the major m e t a l l i c mineral, but chalcopyrite, pyrite^, py.rrhotite s and arsenopyrite are l o c a l l y abundant. The temperature of i n t r u s i o n i s estimated to be i n the range 800-900°C and s t a b i l i t y r e l a t i o n s of coexisting minerals indicate .a temperature of 700-550°C daring s k a r n i f i c a t i o n . The p y r i t e - p y r r h o t i t e geothermometer applied to eight specimens shows that or© deposition, took place within the temperature range 4Q0=-550°C. The composition of: arsenopyrite coexisting with p y r i t e and p y r r b o t i t e in one orebody indicates a confining pressure of 2600 * 1,000 bars during ore formation. The immediate source of ir o n i n these deposits i s believed to be nearby i n t r u s i o n s . The ultimate sourcej, however } i s very probably underlying volcanic rocks which have been assimilated, i n p a r t 2 by an advancing plutoiu Iron i s considered to have been derived from plutons adjacent to the orebodies and to have been c a r r i e d to the s i t e s of deposition as aqueous s u p e r c r i t i c a l solutions of: i r o n c h l o r i d e . Magnetite was pr e c i p i t a t e d from the ore-forming f l u i d by an increase i n pH brought about by reaction with limestone. Changes i n the chemical and ph y s i c a l nature of the ore-forming f l u i d during ore deposition are discussed i n terms of tempera.tures density,, pH 2 p a r t i a l pressures of oxygen and sulphur;, and composition. Hydtothermal processes operative i n formation of the deposits were solvate opposition;, metasomatism, and cavity f i l l i n g . GRADUATE STUDIES F i e l d of Study: Mineral Deposits Wm. H. White Petrology K.C. McTaggart Mineralogy R.M. Thompson A b s t r a c t O r e z o n e s , s k a r n , h o s t r o c k s , a n d a s s o c i a t e d i n t r u s i o n s o f 12 m a g n e t i t e d e p o s i t s w e r e s t u d i e d i n b o t h f i e l d a n d l a b o r -a t o r y t o d e t e r m i n e t h e i r m i n e r a l o g i c a 1 a n d g e o c h e m i c a l c h a r a c t e r -i s t i c s , o r i g i n o f t h e i r o n , a n d f a c t o r s c o n t r o l l i n g e m p l a c e m e n t o f i r o n - b e a r i n g m i n e r a l s . T h i s s t u d y s e e k s a b e t t e r u n d e r -s t a n d i n g o f t h e o r i g i n a n d mode o f o c c u r r e n c e o f c o n t a c t m e 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 w h i c h i n t u r n may p r o v i d e b e t t e r g u i d e s t o t h e i r e x p l o r a t i o n a n d e v a l u a t i o n . L o c a l f o l d s a n d f a u l t s a r e i m p o r t a n t f a c t o r s i n t h e e x p l a c e m e n t 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 a n d l i m e s t o n e o f t h e V a n c o u v e r g r o u p . A d j a c e n t s t o c k s a r e o f i n t e r m e d i a t e c o m p o s i t i o n . P o s t - o r e l e u c o d i o r i t e d y k e s a r e common i n many o r e b o d i e s . ) The a u t h o r p r o p o s e s t h a t t h e p r o c e s s b y w h i c h s k a r n i s f o r m e d be c a l l e d s k a r n i f i c a t i o n i . e . t h e r e p l a c e m e n t b y , c o n v e r s i o n i n t o , o r i n t r o d u c t i o n o f s k a r n . The t e r m w o u l d i n c l u d e a l l ^ p r o c e s s e s by w h i c h s k a r n may be f o r m e d s u c h a s c o n t a c t m e t a m o r p h i s m , c o n t a c t m e t a s o m a t i s m , o r r e g i o n a l m e t a m o r p h i s m . S k a r n i n t h e c o a s t a l B r i t i s h C o l u m b i a r e g i o n i s c o m p o s e d m a i n l y o f g a r n e t ( a n d r a d i t e - g r o s s u l a r i t e ) , p y r o x e n e ( d i o p s i d e - h e d e n b e r g i t e ) , e p i d o t e , a n d m a g n e t i t e . C o n f o r m i t y i i i t o G i b b s P h a s e R u l e a n d t h e n o n - a p p e a r a n c e o f i n c o m p a t i b l e p h a s e s i s s t r o n g e v i d e n c e t h a t e q u i l i b r i u m was a t t a i n e d d u r i n g s k a r n i f i c a t i o n . M a g n e t i t e i s t h e m a j o r m e t a l l i c m i n e r a l b u t c h a l c o p y r i t e , p y r i t e , p y r r h o t i t e , a n d a r s e n o p y r i t e a r e l o c a l l y a b u n d a n t . The t e m p e r a t u r e o f i n t r u s i o n i s e s t i m a t e d t o be i n t h e r a n g e 8 0 0 - 9 0 0 ° C a n d s t a b i l i t y r e l a t i o n s o f c o e x i s t i n g m i n e r a l s i n d i c a t e a t e m p e r a t u r e o f 700-5>5>0°C d u r i n g s k a r n i f i c a t i o n . The p y r i t e - p y r r h o t i t e g e o t h e r m o m e t e r a p p l i e d t o e i g h t s p e c i m e n s s h o w s t h a t o r e d e p o s i t i o n t o o k p l a c e w i t h i n t h e t e m p e r a t u r e r a n g e 1+00-5 5 0 ° C T h e c o m p o s i t i o n o f a r s e n o p y r i t e c o e x i s t i n g w i t h p y r i t e a n d p y r r h o t i t e i n one o r e b o d y i n d i c a t e s a c o n f i n i n g p r e s s u r e o f 2 6 0 0 ! 1 0 0 0 b a r s d u r i n g o r e f o r m a t i o n . T h e i m m e d i a t e s o u r c e o f i r o n i n t h e s e d e p o s i t s i s b e l i e v e d t o be n e a r b y i n t r u s i o n s . T h e u l t i m a t e s o u r c e , h o w e v e r , i s v e r y p r o b a b l y u n d e r l y i n g v o l c a n i c r o c k s w h i c h h a v e b e e n a s s i m i l a t e d , i n p a r t , b y a n a d v a n c i n g p l u t o n . I r o n i s c o n s i d e r e d t o h a v e b e e n d e r i v e d f r o m p l u t o n s a d j a c e n t t o t h e o r e b o d i e s a n d t o h a v e b e e n c a r r i e d t o t h e s i t e s o f d e p o s i t i o n as a q u e o u s s u p e r c r i t i c a l s o l u t i o n s o f i r o n c h l o r i d e . M a g n e t i t e was p r e -c i p i t a t e d f r o m t h e o r e - f o r m i n g f l u i d b y a n i n c r e a s e i n pH b r o u g h t a b o u t b y r e a c t i o n w i t h l i m e s t o n e . i v C h a n g e s i n t h e c h e m i c a l a n d p h y s i c a l n a t u r e o f t h e o r e - f o r m i n g f l u i d d u r i n g o r e d e p o s i t i o n a r e d i s c u s s e d i n t e r m s o f t e m p e r a t u r e , d e n s i t y , p H , p a r t i a l p r e s s u r e s o f o x y g e n a n d s u l p h u r , a n d c o m p o s i t i o n . H y d r o t h e r m a l p r o c e s s e s o p e r a t i v e i n f o r m a t i o n o f t h e d e p o s i t s w e r e s o l v a t e a p p o s i t i o n , m e t a s o m a t i s m , a n d c a v i t y f i l l i n g . V T A B L E OF CONTENTS P a g e A b s t r a c t . . . . . . . . . . . i i CHAPTER I - INTRODUCTION A c k n o w l e d g e m e n t s Ij. Summary o f p r e v i o u s w o r k . . . . . 5 P h y s i o g r a p h y a n d c l i m a t e . . . . . . . 13 R e g i o n a l g e o l o g y l l | -CHAPTER I I - M I N E R A L O G Y AND G E O C H E M I S T R Y I n t r u s i o n s 23 V o l c a n i c r o c k s I+.0 L i m e s t o n e M e t a l l i c m i n e r a l s . 6 7 CHAPTER I I I - ENVIRONMENT OF ORE D E P O S I T I O N C o n f i n i n g p r e s s u r e . . . . . 79 T e m p e r a t u r e o f t h e p l u t o n 8 3 T e m p e r a t u r e o f s k a r n i f i c a t i o n 8% T e m p e r a t u r e o f f o r m a t i o n o f m e t a l l i c m i n e r a l s . . 9U-P a r t i a l p r e s s u r e o f o x y g e n 9$ P a r t i a l p r e s s u r e o f s u l p h u r 102 C H A P T E R I V - G E N E S I S O r i g i n o f i r o n compounds . 103 C o m p o s i t i o n o f t h e o r e - f o r m i n g f l u i d s 109 O r e c o n t r o l s 121 H y d r o t h e r m a l p r o c e s s e s 128 CHAPTER V - CONCLUSIONS O r i g i n a n d c l a s s i f i c a t i o n o f t h e d e p o s i t s . . . . 133 S u g g e s t i o n s f o r f u r t h e r w o r k '. 136 R E F E R E N C E S AND S E L E C T E D B I B L I O G R A P H Y 137 v i P a g e A P P E N D I X I - D e s c r i p t i o n s o f p r o p e r t i e s 1. T h e A r g o n a u t Company L i m i t e d . . . . . . . . . 1^3 2 . T e x a d a M i n e s L i m i t e d 162 3 . E m p i r e D e v e l o p m e n t Company L i m i t e d . . . . . . 181+ 1+. B r y n n o r M i n e s L i m i t e d 198 5 . N i m p k i s h I r o n M i n e s L i m i t e d 208 6 . Z e b a l l o s I r o n M i n e s L i m i t e d 216 7e J e d w a y I r o n O r e L i m i t e d 231 8 . C o a s t C o p p e r Company L i m i t e d . . . . . . . . . . 237 9 . W e s f r o b M i n e s L i m i t e d 21+0 A P P E N D I X I I - T h e o r i g i n o f " c l o u d e d " f e l d s p a r -a r e v i e w . . . . . 21+1+ A P P E N D I X I I I - C h e m i c a l a n a l y s e s a n d norms . . . . . . 21+8 A P P E N D I X I V - P l a t e s 2£6 F I G U R E S F i g u r e P a g e 1. L o c a t i o n s o f c o n t a c t m e 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 , s o u t h w e s t e r n B r i t i s h C o l u m b i a . . . 2 2 . A n n u a l s h i p m e n t s o f m a g n e t i t e c o n c e n t r a t e , B r i t i s h C o l u m b i a 3 3 . M o d e s o f i n t r u s i o n s a d j a c e n t t o m a g n e t i t e d e p o s i t s , B r i t i s h C o l u m b i a 21+ 1+. D i a g r a m s h o w i n g c o m p o s i t i o n s o f i n t r u s i o n s a d j a c e n t t o c o n t a c t m e t a s o m a t i c m a g n e t i t e C J , 6 p O S l t S 0 0 * • • • e e • 6 0 « • « « e • • 26 5>. E m p i r e D e v e l o p m e n t C o . , l o c a l g e o l o g y . . . . 3 £ v i i F i gure Page 6 . 7 . 8 . 9 . 1 0 a . 10b, 1 1 . 1 2 . 1 3 . 11+. 1 5 . 1 6 . 1 7 . 1 8 . 1 9 . Coast Copper s t o c k , Vancouver I s l a n d . Graphs showing v a r i a t i o n s i n t o t a l i r o n c o n t e n t and i n t h e r a t i o of i r o n i n m a g n e t i t e to t o t a l i r o n Q 0 0 « 0 • Diagram showing c o m p o s i t i o n s of v o l c a n i c r ocks a s s o c i a t e d w i t h c o n t a c t metasomatic m a g n e t i t e d e p o s i t s « e e 0 • 0 0 0 0 0 0 C o m p o s i t i o n o f g a r n e t i n skarn as determined by c e l l edge and r e f r a c t i v e i n d e x . . . . . B e g i n n i n g - o f - m e l t i n g curves of g r a n i t e and o l i v i n e t h o l e i i t e . . . . . . . . 0 0 0 G r o s s u l a r i t e-hydrogros s u l a r i t e s t a b i l i t y r e l a t i o n s i n the p r e s e n c e of s i l i c a . . . . S t a b i l i t y r e l a t i o n s i n t h e system g r o s s u l a r i t e - H ^ O . . . . . . . . . . . . . I r o n H i l l mine, diagrammatic s e c t i o n A-A' . Contour o f t o p of Quinsam g r a n o d i o r i t e s t o c k s u b - o u t c r o p , I r o n H i l l mine Contour of f i r s t appearance o f ore zone above Quinsam g r a n o d i o r i t e s t o c k , I r o n H i l l mine. Texada Mines L t d . , g e o l o g i c a l s k e t c h . . . P r e s c o t t mine, Texada I s l a n d . Diagram showing c h e m i c a l changes a c r o s s a c o n t a c t between q u a r t z monzonite and l i m e s t o n e . Texada Mines L t d . , Y e l l o w K i d d e p o s i t , d iagrammatic s e c t i o n A-A' . . . Empire Development Co. L t d . , M e r r y Widow d e p o s i t , diagrammatic s e c t i o n . . . . . . Brynnor Mines L t d . , diagrammatic s e c t i o n A-A Z e b a l l o s I r o n Mines L t d . , g e o l o g i c a l s k e t c h 38 1L2 53 8 5 89 89 158 159 160 168 173 176 190 201+ 2 1 8 v i i 1 F i g u r e Page 2 0 . Topography, Ridge d e p o s i t . . . . . . . . . . 226 2 1 . D i p n e e d l e s u r v e y , Ridge d e p o s i t . . . . . . 2 2 7 2 2 . Geology, Ridge d e p o s i t . . . . . . . . . . . 2 2 8 2 3 . Jedway I r o n Ore L t d . , J e s s i e d e p o s i t , diagrammatic s e c t i o n A-A' . . . . . 2 3 5 TABLES Table Page 1. Bedrock s t r a t i g r a p h y of Vancouver, Texada, and Moresby I s l a n d s , B r i t i s h Columbia . . . . . 15 2 . Comparison of c o m p o s i t i o n s of Nootka g r a n i t e , I t s " c o n t a m i n a t e d " border phase, and a n d e s i t e c o u n t r y r o c k 2 8 3 . A n a l y s e s showing changes a c r o s s the c o n t a c t of S a a n i c h g r a n o d i o r i t e and b a s a l t 30 1+. C o m p o s i t i o n of P e r r y Lake g r a n i t e and a s s o c i a t e d border phase i n c o n t a c t w i t h l i m e s t o n e . . . 32 5 . G i l l i e s s t o c k q u a r t z monzonite and a s s o c i a t e d border phase . . 33 6. S p e c t r o g r a p h s a n a l y s e s o f gabbro i n T r a v e r s e s 'A' and 'B', Coast Copper s t o c k . . 36 7 . Comparison o f i n t e r p l a n a r s p a c i n g s f o r b i r e f r i n g e n t and i s o t r o p i c g a r n e t s of c o m p o s i t i o n A n ^ G r ^ A l g g •-• 57 8 . P a r t i a l a n a l y s e s o f m a g n e t i t e c o n c e n t r a t e s , B r i t i s h Columbia . 7 0 i x T a b l e Page 9 . C l a s s i f i c a t i o n o f s e v e n i n t r u s i o n s i n t o t h r e e d e p t h z o n e s . . . . . . 82 1 0 . E s t i m a t e d 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 s o f p y r r h o t i t e c o e x i s t i n g w i t h p y r i t e 97 11. P r e s c o t t m i n e , T e x a d a I s l a n d . G e n e r a l c h a r a c t e r i s t i c s o f z o n e s d e v e l o p e d w i t h i n a n d a r o u n d t h e o r e b o d y . . . . . 172 12 . C h e m i c a l a n a l y s e s a n d n o r m s o f i n t r u s i o n s n e a r m a g n e t i t e d e p o s i t s 2l|9 13. C h e m i c a l a n a l y s e s a n d norms o f v o l c a n i c r o c k s n e a r m a g n e t i t e d e p o s i t s 25>1 II4.. C h e m i c a l a n a l y s e s o f h o s t r o c k l i m e s t o n e . . 253 15. C h e m i c a l a n a l y s e s a n d " n o r m s " o f s k a r n . . . 251+. 16. L o c a t i o n s o f s p e c i m e n s c o l l e c t e d f o r c h e m i c a l a n a l y s i s 255 P L A T E S P l a t e Page I . L a u m o n t i t e v e i n i n g s e r i c i t i z e d Q u i n s a m g r a n o d i o r i t e 257 I I . R e p l a c e m e n t o f G i l l i e s q u a r t z m o n z o n i t e b y g a r n e t s k a r n 257 I I I . T e x a d a g r o u p a n d e s i t e p a r t l y r e p l a c e d b y g a r n e t s k a r n . 258 IV. C o n t a c t b e t w e e n G i l l i e s q u a r t z m o n z o n i t e , M a r b l e B a y l i m e s t o n e , a n d o r e 258 X P l a t e Page V. " B r e c c i a " o r e , Y e l l o w K i d mine 259 V I . M a g n e t i t e w i t h c a v i t i e s p a r t l y f i l l e d w i t h m i l k y q u a r t z c r y s t a l s and g o e t h i t e . . . . 2 5 9 V I I . Greenstone dyke i n l i m e s t o n e 2 6 0 V I I I . M a s s i v e m a g n e t i t e i n c o n t a c t w i t h bedded l i m e s t o n e . . . . . . . . . . . 2 6 0 IX. M a g n e t i t e orebody between m i g m a t i t e and l i m e s t o n e 2 6 l X. D i o p s i d e c r y s t a l s of unusual form . . . . 261 X I . An i l l u s t r a t i o n o f t h e t y p i c a l sharp m a g n e t i t e - l i m e s t o n e c o n t a c t 262 X I I . M a g n e t i t e f i l l i n g f r a c t u r e s i n b r e c c i a t e d a n d e s i t e • 2 6 2 X I I I . A l t e r n a t i n g l a y e r s of c o a r s e l y c r y s t a l l i n e m a g n e t i t e and c a l c i t e 2 6 2 XIV. S i m i l a r t o P l a t e X I I I 2 6 3 XV. C o n t a c t o f garnet s k a r n and l i m e s t o n e . . 2 6 3 XVI. An example of c o l l o f o r m m a g n e t i t e . . . . 2 6 3 X V I I . Garnet s k a r n w i t h r e l i c t g r a n i t i c t e x t u r e of h o s t r o c k q u a r t z monzonite 261+ X V I I I . P o s t - o r e c a l c i t e s u r r o u n d i n g fragments of m a g n e t i t e 261+ XIX. S k a r n i f i c a t i o n o f e p i d o t i z e d q u a r t z monzonite 261+ XX. C a l c i t e f i l l i n g openings between e u h e d r a l a n d r a d i t e c r y s t a l s . 2 6 5 XXI. Same as P l a t e XX but w i t h c r o s s e d n i c o l s . 2 6 5 X X I I . M a g n e t i t e f i l l i n g openings between s u b h e d r a l a n d r a d i t e c r y s t a l s . . 2 6 5 X X I I I . M a g n e t i t e r e p l a c i n g g a r n e t s k a r n 2 6 6 X I MAPS Map 1. Geology of the I r o n H i l l mine ( i n p o c k e t ) 2. Geology of t h e P r e s c o t t mine . . . . . . " 3 . Geology of the Y e l l o w K i d mine " 1+. Geology of t h e P a x t o n mine " 5 . Geology o f t h e K i n g f i s h e r mine . . . . . " 6 . Geology o f the Brynnor mine " 7 . Geology of t h e F.L. (Ford) mine " 8 . Geology of the I r o n Crown (Kla a n c h ) mine. " 9 . Geology of t h e J e s s i e mine . . . . . . . " CHAPTER I - INTRODUCTION Many c o n t a c t metasomatic m a g n e t i t e d e p o s i t s o c c u r on i s l a n d s t h a t f r i n g e the c o a s t of B r i t i s h Columbia ( F i g . 1), A l t h o u g h most of t h e s e d e p o s i t s have been known f o r s e v e r a l decades and some have been s p o r a d i c a l l y e x p l o r e d , i t was not u n t i l !, 1 9 ^ 2 , w i t h a r i s i n g Japanese demand, t h a t i r o n ore p r o d u c t i o n became an e s t a b l i s h e d i n d u s t r y i n B r i t i s h C o l u m b i a . The f i r s t d e p o s i t mined was a t I r o n H i l l , near Campbell R i v e r on Vancouver I s l a n d . T o t a l p r o d u c t i o n from t h i s d e p o s i t , from 1952 t o 1 9 5 7 , amounted t o 1 , 9 9 8 , 5 2 6 s h o r t t o n s of i r o n ore c o n c e n t r a t e . S i n c e 1957 o t h e r mines have opened and p r o d u c t i o n has r i s e n s t e a d i l y ( F i g . 2 ) . In 1962 t o t a l i r o n c o n c e n t r a t e p r o d u c t i o n i n B.C. reached 1,7kk-»h-2> 1 s h o r t t o n s , a c c o u n t i n g f o r about Q% of the t o t a l v a l u e o f m i n e r a l p r o -d u c t i o n i n t h e P r o v i n c e . T h i s t h e s i s i s t h e r e p o r t of a p e t r o g r a p h i c a l , m i n e r a l o g i c a l , and geochemical s t u d y of c o n t a c t metasomatic m a g n e t i t e d e p o s i t s i n w e s t e r n B r i t i s h C o lumbia. Ore zones, s k a r n r o c k s , and a s s o c i a t e d i n t r u s i o n s were s t u d i e d i n both f i e l d and l a b o r a t o r y t o d e t e r m i n e t h e i r m i n e r a l o g i c a l and geochemical c h a r a c t e r i s t i c s , o r i g i n of t h e i r o n , and f a c t o r s c o n t r o l l i n g emplacement of i r o n - b e a r i n g m i n e r a l s . -2-" 60° FIGURE I LOCATIONS OF CONTACT METASOMATIC MAGNETITE DEPOSITS, SOUTHWESTERN BRITISH COLUMBIA 1 Argonaut Company Ltd. 2 Texada Mines Ltd. Empire Development Co. Ltd. Brynnor Mines Ltd. NimpKlsh Iron Mines Ltd. Zeballos Iron Mines Ltd. Jedway Iron Ore Ltd. 8 Coast Copper Co. 9 Wesfrob Mines Ltd. B R I T I S H C O L U M B I A • Merritt 'ancouver 49° N U S A Bose map by Department of Geography, U . B . C - 3 -F I G U R E 2 Annual shipments of magnetite concentrate, British Columbia. (From BC Min. of Mines Ann. Rep. 1952-62) I t i s ex p e c t e d t h a t t h i s s t u d y w i l l l e a d t o a c c u r a t e d e s c r i p t i o n s and a b e t t e r u n d e r s t a n d i n g of the o r i g i n and mode of o c c u r r e n c e of c o n t a c t metasomatic m a g n e t i t e d e p o s i t s and p r o v i d e b e t t e r guides to t h e i r e x p l o r a t i o n and e v a l u a t i o n . Ac k now1e d g eme n t s The a u t h o r takes t h i s o p p o r t u n i t y to g r a t e f u l l y acknowledge the s u p p o r t and encouragement of Dr. G.A. Gross of the G e o l o g i c a l S u r v e y of Canada, who c o n c e i v e d the p r o j e c t , and of t h e G e o l o g i c a l Survey. C o o p e r a t i o n o f many m i n i n g companies and t h e i r o f f i c e r s i s g r e a t l y a p p r e c i a t e d . In p a r t i c u l a r , t h e a u t h o r would l i k e t o thank t h e f o l l o w i n g ; ; D.P. Shepard, Manager, Re a l E s t a t e Dept., Canadian P a c i f i c R a i l w a y Company, Vancouver? J . Lamb, G e o l o g i s t (I96I), Empire Development Co. L t d . , and Manager (1962), Z e b a l l o s I r o n Mines L t d . ; B. L. A l e x a n d e r , General Manager, and P. D a v i e s , G e o l o g i s t , Texada Mines L t d . ; T.R. Wearing, Manager, and W.I. N e l s o n , G e o l o g i s t , Brynnor Mines L t d . ; S.V. Wines, P r o j e c t Manager, and E. N e l s o n , G e o l o g i s t , Nimpklsh I r o n Mines L t d . ; J . M. S t i t t , Manager, and D.F. I r v i n g , R e s i d e n t E n g i n e e r , Jedway I r o n Ore Ltd.5 K . P o l k , R e s i d e n t G e o l o g i s t , Wesfrob Mines L t d . ; C. Rennie, C h i e f G e o l o g i s t , Craigmont Mines L t d . ; H.G. B a r k e r , Manager, Coast Copper Co. To P r o f e s s o r Wm. H. White, Department of Geology, U n i v e r s i t y of B r i t i s h Columbia, and Dr. J.E. Armstrong, G e o l o g i c a l Survey of Canada, t h e w r i t e r wishes t o express h i s a p p r e c i a t i o n of t h e i r h e l p f u l c r i t i c i s m d u r i n g the p r o j e c t and the p r e p a r a t i o n o f t h i s m a n u s c r i p t . T e c h n i c a l a s s i s t a n c e was a f f o r d e d by the G e o l o g i c a l S u r v e y of Canada and f i n a n c i a l a s s i s t a n c e was provided,, i n p a r t , by a N a t i o n a l R e s e a r c h C o u n c i l of Canada F e l l o w s h i p and a Quebec Department of M i n e s ' S c h o l a r s h i p . The a u t h o r was a b l y a s s i s t e d i n the f i e l d by M e s s r s . R. Vogan and K. L. C o d d l i n g . Summary of p r e v i o u s work The l i t e r a t u r e of B r i t i s h Columbia m a g n e t i t e de-p o s i t s i s e x t e n s i v e , d a t i n g back t o the l a s t q u a r t e r of the 19th C e n t u r y . Most of the e a r l y a r t i c l e s a r e l i m i t e d t o d e s c r i p t i o n s of n a t u r a l exposures and l a c k d e t a i l e d m i n e r a l -o g i c a l , p e t r o g r a p h i c a l , and s t r u c t u r a l data.-The author w i l l r e v i e w those works w h i c h , i n h i s o p i n i o n , have made s i g n i f i c a n t ' c o n t r i b u t i o n s t o an under-s t a n d i n g of t h e c h a r a c t e r and o r i g i n of B r i t i s h Columbia con-t a c t metasomatic m a g n e t i t e d e p o s i t s . The e a r l i e s t o f t h e s e works was by K i m b a l l ( 1897) i n w h i c h he r e c o g n i z e d t h e d e p o s i t s as " h y d r o - c h e m i c a l " replacements but d i s t i n g u i s h e d two s e p a r a t e t y p e s . In t h e f i r s t t y p e , a m o r p h o l o g i c a l replacement of l i m e s t o n e by double d e c o m p o s i t i o n between f e r r o u s s a l t s g enerated from f e r r o u s s i l i c a t e s and c a l c i u m c a r b o n a t e , K i m b a l l c o n s i d e r e d the f e r -r i f e r o u s m a t e r i a l to have been d e r i v e d from an extraneous source "through s i m p l e p e r m u t a t i o n s and r e a c t i o n s " ( K i m b a l l , l 8 ' 9 7 , p. 1 3 ) » The second t y p e , a p a r t i a l r eplacement of f e r r o r s s i l i c a t e s i n weathered b a s i c igneous r o c k s , i s brought about through i n i t i a l d e c o m p o s i t i o n o f f e r r o u s and f e r r i c s i l i c a t e s ( c h i e f l y the f o r m e r ) . These are then c o n s i d e r e d t o form s o l u b l e a l k a l i n e c a r b o n a t e s a l o n g w i t h f e r r o u s s a l t s . T h i s l e a d s , i n t u r n , t o double d e c o m p o s i t i o n and f i n a l l y to i s o l a t i o n o f i n s o l u b l e r e s i d u e s , presumably m a g n e t i t e . I t was suggested t h a t the " u n i o n of m a g n e t i t e m o l e c u l e s i s doubt-l e s s promoted a l s o by p o l a r i t y " a l t h o u g h K i m b a l l d i d not e l a b o r a t e on t h i s i n t r i g u i n g p o i n t ( I b i d , p . 15>) . A l t h o u g h i t s u g g e s t s a number of i n t e r e s t i n g i d e a s and u n d o u b t e d l y p o r -t r a y s o r i g i n a l t h o u g h t s on t h e o r i g i n of c o n t a c t - t y p e m a g n e t i t e d e p o s i t s , K i m b a l l ' s work s u f f e r s from an a n t i q u i t y of language which i s d i f f i c u l t t o read and u n d e r s t a n d . One c a n , however. - 7 -r e c o g n i z e i n h i s f i r s t type of d e p o s i t an e a r l y attempt t o d e s c r i b e a p r o c e s s of replacement by h y d r o t h e r m a l s o l u t i o n s emanating from an o u t s i d e s o u r c e . The i r o n i s not c o n s i d e r e d to have been c a r r i e d as m a g n e t i t e b u t , i n s t e a d , as a s o l u b l e s a l t w h i c h r e a c t e d w i t h l i m e s t o n e t o form m a g n e t i t e . K i m b a l l ' s second t y p e of d e p o s i t , because i t r e p l a c e s o n l y m a f i c miner-a l s i n the c o u n t r y r o c k , would r e s u l t i n a low grade d i s -seminated m a g n e t i t e d e p o s i t . T h i s p r o c e s s i s c o n s i d e r e d t o be of r e l a t i v e l y minor i m p o r t a n c e . In a d i s c u s s i o n of the g e n e s i s of s e v e r a l s m a l l m a g n e t i t e bodies found i n s o u t h e r n Vancouver I s l a n d , C l a p p ( 1 9 1 3 ) c o n c l u d e d t h a t t h e y owed t h e i r o r i g i n t o i n t r u s i o n of a d j a c e n t p l u t o n s . A p p a r e n t l y , he was impressed by the broken appearance o f r o c k a s s o c i a t e d w i t h c e r t a i n d e p o s i t s and i n f e r r e d from t h i s t h a t i r o n was emplaced as m a g n e t i t e magma, i n a n a l o g y t o an i n t r u s i v e b r e c c i a s u c h as t h a t produced, by a s i l i c a t e magma. T h i s t h e o r y may be s u b s t a n t i a t e d i n p a r t by the r e c e n t d i s c o v e r y of what appears t o be a hi g h - g r a d e {6%% Fe) m a g n e t i t e " f l o w " i n n o r t h e r n C h i l e ( P a r k , I 9 6 l j R u i z and E r i c k s e n , 1 9 6 2 , p p 9 9 - 9 9 ) . The porous t e x t u r e of t h e " f l o w " i n d i c a t e s i t was at one time p r o b a b l y h i g h l y charged w i t h gaseous m a t e r i a l s and t h e s e v o l a t i l e s may have lowered the m e l t i n g temperature of t h e m i x t u r e . Perhaps Clapp's "magma" was s i m i l a r t o t h i s . - 8 -E l e v e n y e a r s a f t e r Clapp's memoir, Swanson (192)4.) d i s c u s s e d at some l e n g t h the o r i g i n of c o n t a c t metasomatic ma g n e t i t e d e p o s i t s , p a r t i c u l a r l y those o c c u r r i n g on Texada I s l a n d . He d i s t i n g u i s h e d two e f f e c t s o f i n t r u s i o n of t h e G i l l i e s s t o c k ; namely, c o n t a c t metamorphism ( m a i n l y r e c r y s t a l -l i z a t i o n ) and metasomatism ( r e s u l t i n g i n an e x t e n s i v e r e p l a c e -ment of c o u n t r y r o c k ) . C o n c e r n i n g the m a g n e t i t e d e p o s i t s , t h r e e f e a t u r e s were c o n s i d e r e d t o be d i s t i n c t i v e of t h e s e b o d i e s ? ( 1 ) i r r e g u l a r d i s t r i b u t i o n ( 2 ) marked c h e m i c a l changes wh i c h were a p p a r e n t l y i n v o l v e d i n ore f o r m a t i o n and ( 3 ) replacement of t h e p a r e n t i n t r u s i v e r o c k as w e l l as l i m e s t o n e and v o l c a n i c r o c k . An e x c e l l e n t d e s c r i p t i o n of the m i n e r a l o g y of t h e host r o c k s , i n t r u s i o n s , and s k a r n then f o l l o w e d . Swanson d e c i d e d t h a t "....replacement was q u a n t i t a t i v e l y the dominant p r o c e s s , and t h a t a l l the m i n e r a l s of t h e d e p o s i t are a t l e a s t p a r t l y metasomatic" (Swans on, 192)4, p. 131A). The paper c o n c l u d e d w i t h a summary of f a c t o r s Swanson b e l i e v e d c o n t r o l l e d the c h a r a c t e r and p o s i t i o n of the d e p o s i t s . H i s summary, b r i e f , but i n f o r m a t i v e i s quoted be lows The d e p o s i t s were formed by magmatic s o l u t i o n s i n whic h t h e m a t e r i a l s were c o n c e n t r a t e d by t h e c r y s t a l l i z a t i o n of the i n t r u s i v e . The a s s i m i l a t i o n of l i m e s t o n e by the magma may have been a f a c t o r of gr e a t s i g n i f i c a n c e , as f e r r o u s and f e r r i c o x i d e s were t h e r e b y thrown out of t h e pyroxene m o l e c u l e and _ 9 -made a v a i l a b l e f o r s e g r e g a t i o n as m a g n e t i t e . The r e l e a s e of "the s o l u t i o n s from t h e i n t r u s i v e was e f f e c t e d by f r a c t u r i n g caused by c o o l i n g o f t h e mass and, as a consequence, the d i s t r i b u t i o n of the d e p o s i t s i s m a i n l y c o n t r o l l e d by t h e s t r u c t u r a l c o n d i t i o n s a t t h e ti m e of r e p l a c e m e n t , w h i c h f a v o u r e d the movement o f s o l u t i o n s a l o n g the c o n t a c t zone. From a c o n s i d e r a t i o n of the p h y s i c a l p e r m e a b i l i t y and t h e c h e m i c a l c o m p o s i t i o n of the ro c k s i n t o which the s o l u t i o n s were l e d , i t i s co n c l u d e d t h a t t h e p o r p h y r i t e was u n f a v o u r a b l e both p h y s i c a l l y and c h e m i c a l l y , t h a t t h e i n t r u s i v e was f a v o u r a b l e p h y s i c a l l y but not c h e m i c a l l y , and t h a t t h e l i m e s t o n e was f a v o u r a b l e c h e m i c a l l y but not p h y s i c a l l y . The c h e m i c a l f a c t o r was p r o b a b l y i n c o n t r o l , as the cons t a n t removal of m a t e r i a l , f a c i l i t a t e d by the a d d i t i o n o f c a l c i t e t o t h e s o l u t i o n s , was as n e c e s s a r y f o r t h e f o r m a t i o n o f e x t e n s i v e r eplacements as t h e ac c e s s o f new m a t e r i a l . The heterogeneous p a r t s of t h e i n t r u s i v e which i n c l u d e d b l o c k s of l i m e s t o n e , and the tongues of l i m e s t o n e p r o j e c t i n g i n t o the s t o c k , were e s p e c i a l l y s u i t e d to re p l a c e m e n t , both p h y s i c a l l y and c h e m i c a l l y , and c o n t a i n the l a r g e s t d e p o s i t s . F i n a l l y , t he o x i d i z i n g e f f e c t of the carbon d i o x i d e was p r o b a b l y e f f e c t i v e i n t h e f o r m a t i o n of t h e r e l a t i v e l y pure d e p o s i t s of m a g n e t i t e . (Swanson, 192L. ,p. 1UJ+A) . Swanson's c o n c l u s i o n s were deduced e n t i r e l y from f i e l d and p e t r o g r a p h i c o b s e r v a t i o n s . The p r e s e n t m a n u s c r i p t , however, s t r o n g l y s u p p o r t s many of h i s d e d u c t i o n s c o n c e r n i n g n a t u r e of the ore f l u i d s , exchange of m a t e r i a l , and p h y s i c a l c h e m i s t r y of o r e - f o r m i n g e n v i r o n m e n t s . Uglow ( 1 9 2 6 ) was one of the f i r s t t o note and emphasize the s i g n i f i c a n c e of t h e a r e a l a s s o c i a t i o n of m a g n e t i t e d e p o s i t s w i t h the Vancouver group. He c o n s i d e r e d - 1 0 -the m a g n e t i t e o c c u r r e n c e s t o be o f t h e " c o n t a c t metamorphic" type and r e c o g n i z e d t h r e e s u b - t y p e s : (1) m a g n e t i t e d e p o s i t s i n l i m e s t o n e (2) m a g n e t i t e d e p o s i t s i n v o l c a n i c r o c k s and (3) c o p p e r - i r o n d e p o s i t s i n l i m e s t o n e , v o l c a n i c s , and d i o r i t e . The p a r a g e n e t i c s e q u e n c e — s i l i c a t e s , m a g n e t i t e , b o r n i t e , and c h a l c o p y r i t e — s u g g e s t e d by e a r l i e r w r i t e r s and s u p p o r t e d i n p a r t by l a t e r ones, was a l s o g i v e n i n Uglow's paper. Concern-in g g e n e s i s , Uglow r e j e c t e d Clapp's h y p o t h e s i s of a m a g n e t i t e ' magma i n f a v o u r of replacement by "tenuous s o l u t i o n s " and gave s e v e r a l b r i e f d e s c r i p t i o n s s u p p o r t i n g t h i s t h e o r y . In a s h o r t d e s c r i p t i o n of t h e I r o n H i l l d e p o s i t w h i c h l i e s i n the a x i a l zone of a t i g h t s y n c l i n e composed of both greenstone and l i m e s t o n e , B l a c k (1952) suggested t h a t d u r i n g d e f o r m a t i o n the greenstone became c l o s e l y f r a c t u r e d whereas t h e l i m e s t o n e m e r e l y f l o w e d and r e c r y s t a 1 1 i z e d . Because t h e f r a c t u r e d greenstone was more permeable t o m i n e r a l i z i n g f l u i d s than l i m e s t o n e and o f f e r e d l a r g e r s u r f a c e a r e a s f o r r e a c t i o n , i t was p r e f e r e n t i a l l y r e p l a c e d by ore m i n e r a l s . B l a c k o b s e r v e d , however, t h a t such replacement t o o k p l a c e near l i m e s t o n e and suggested t h a t the pr e s e n c e of ca r b o n a t e was n e c e s s a r y . In 1952 and a g a i n i n 1956, Bacon b r i e f l y r e v i e w e d the n a t u r e o f c o n t a c t metasomatic i r o n d e p o s i t s i n B r i t i s h -11-C o l u m b i a . In these r e p o r t s , he noted the c l o s e a s s o c i a t i o n of m a g n e t i t e w i t h l i m e s t o n e and emphasized t h a t " l i m e s t o n e assumes the utmost s i g n i f i c a n c e i n any s e a r c h f o r new magnet-i t e d e p o s i t s , and b e l t s of t h i s r o c k .should be i n v e s t -i g a t e d t h o r o u g h l y " ( 1 9 5 2 , p . A 2 l 8 ) . He f u r t h e r warned t h a t . s u r f a c e exposures of t h i s type of m a g n e t i t e d e p o s i t a r e mis-l e a d i n g and t h a t tonnage e s t i m a t e s s h o u l d be based on c l o s e l y -spaced diamond d r i l l h o l e s . To d i s t i n g u i s h d e p o s i t s of c o n t a c t metasomatic o r i g i n from t a c o n i t e d e p o s i t s and m a g n e t i t e - b e a r i n g p y r o x e n i t e s , a l l o f which o c c u r i n B.C., Bacon l i s t e d the main c h a r a c t e r -i s t i c s of t h e s e t h r e e types of d e p o s i t s ( 1 9 5 2 ,p. 12.5) . C o n t a c t metasomatic t y p e are d i s t i n g u i s h e d by: 1. M a g n e t i t e g e n e r a l l y a s s o c i a t e d w i t h s k a r n i n which brown garnet Is commonly the dominant m i n e r a l . 2. Occurrence a l o n g or c l o s e t o c o n t a c t s between f o l d e d metamorphosed r o c k s and Coast i n t r u s i v e r o c k s . 3 . P r o x i m i t y t o l i m e s t o n e , or i n l i m e s t o n e . l±. H i g h l y i r r e g u l a r shape and g e n e r a l l y abrupt t e r m i n a t i o n s . R e l a t i v e l y h i g h i r o n c o n t e n t , r a n g i n g from 35% t o n e a r l y 60%. S u t h e r l a n d - B r o w n ( 1 9 6 2 ) summarized the o b s e r v a t i o n s made d u r i n g t h e decade 1 9 5 2 - 6 2 by o f f i c e r s o f t h e B.C. Department of Mines and P e t r o l e u m R e s o u r c e s . His summary -12-s t r e s s e d the c o n s t a n t a s s o c i a t i o n o f t h e s e d e p o s i t s w i t h Upper T r i a s s i c l i m e s t o n e but pointe.d out t h a t a m a j o r i t y of d e p o s i t s are a c t u a l l y found i n v o l c a n i c r o c k s e i t h e r above or below a l i m e s t o n e u n i t (Quatsino f o r m a t i o n ) . I t i s perhaps s i g n i f i c a n t t o note t h a t Sutherland-Brown c o n s i d e r e d both i r o n and c a l c i u m to have been added to the v o l c a n i c s d u r i n g ore f o r m a t i o n . H e r e t o f o r e most w r i t e r s had t a c i t l y assumed t h a t c a l c i u m had moved out o f , r a t h e r than i n t o , the a r e a i n w h i c h ore was b e i n g formed. S u t h e r l a n d - B r o w n c o n s i d e r e d the r e l a t i v e l y common o c c u r r e n c e o f Q u a t s i n o l i m e s t o n e t o be t h e main r e a s o n why m a g n e t i t e appears t o be p r e f e r e n t i a l l y a s s o c i a t e d w i t h i t . A t h i n n e r , l e s s w i d e l y d i s t r i b u t e d Upper P a l e o z o i c l i m e s t o n e u n i t i s not a s s o c i a t e d w i t h any known economic m a g n e t i t e d e p o s i t i n s o u t h w e s t e r n B r i t i s h Columbia. A map was i n c l u d e d to show the d i s t r i b u t i o n of Upper T r i a s s i c ( Q u a t s i n o ) l i m e -s t o n e i n w e s t e r n B r i t i s h C o lumbia. In h i s s h o r t summary, Sut h e r l a n d - B r o w n was the f i r s t t o note the abundance of p o s t -ore f e l d s p a r p o r p h y r y dykes i n mine areas and t h e i r s c a r c i t y e lsewhere i n s i m i l a r c o u n t r y r o c k s , but the s i g n i f i c a n c e of t h i s a s s o c i a t i o n was u n s t a t e d . - 1 3 -P h y s i o g r a p h y and c l i m a t e The d e p o s i t s c o n s i d e r e d i n t h i s r e p o r t are on i s l a n d s t h a t f r i n g e the c o a s t of B r i t i s h C o l u m b i a . The Queen C h a r l o t t e and Vancouver I s l a n d s are mountainous, w i t h b o r d e r i n g lowlands on t h e i r n o r t h e a s t s i d e s . In the Queen C h a r l o t t e s , the maximum e l e v a t i o n i s about 3000 f e e t but on Vancouver I s l a n d s e v e r a l mountains r i s e above 6000 f e e t and one, Golden H i n d e , exceeds 7200 f e e t i n e l e v a t i o n . Texada I s l a n d i s l o w - l y i n g , the h i g h e s t peak r e a c h i n g o n l y 2892 f e e t . The mean annual range i n temperature o f c o a s t a l s t a t i o n s i s 1 6 ° F i n the s o u t h and 2 3 ° F i n the n o r t h e r n p a r t of t h e a r e a . W i n t e r temperatures on the coast average 3 9 ° F and summers about 5 7 ° F . The f r o s t - f r e e p e r i o d v a r i e s from 150 t o 250 days (Chapman,1 9 5 2 ,pp.1 0 - 1 2 ) . Heavy p r e c i p i t a t i o n i s c h a r a c t e r i s t i c o f the c o a s t a l area a l t h o u g h o n l y about 1-6% i s snow. L o c a l l y , u n u s u a l l y h i g h amounts of r a i n have been r e c o r d e d ; f o r i n s t a n c e , Henderson Lake, l e s s than 20 m i l e s east of Brynnor Mines L t d . on Vancouver I s l a n d ( F i g . 1) has the h i g h e s t r e c o r d e d p r e c i p i t a t i o n i n one year ( 2 5 1 . 3 i n c h e s ) on t h e c o n t i n e n t . R e l a t i v e h u m i d i t y i n the c o a s t a l a r e a i s g e n e r a l l y h i g h throughout the y e a r , a v e r a g i n g 70-85% (Chapman,1952,pp. 1 0 - 1 2 ) . R e g i o n a l g e o l o g y The geology of t h e c o a s t a l r e g i o n o f B r i t i s h C olumbia i s not y e t f u l l y mapped. Mapping i n the a r e a i s d i f f i c u l t because of heavy f o r e s t c o v e r , p r e c i p i t o u s s l o p e s , and g e n e r a l l y poor weather d u r i n g t h e f i e l d s eason. Some areas were mapped i n d e t a i l 20 ye a r s ago whereas o t h e r s a r e o n l y now b e i n g e x p l o r e d on a r e c o n n a i s s a n c e s c a l e . St r a t i g r a p h y The p r e s e n t s t a t e o f knowledge o f t h e s t r a t i g r a p h y on Vancouver I s l a n d , Texada I s l a n d , and Moresby I s l a n d ( s o u t h e r n Queen C h a r l o t t e s ) i s shown i n T a b l e 1. Unconform-i t i e s a r e shown but i n t r u s i v e c o n t a c t s o r p e r i o d s o f i n t r u s i o n a re not i n d i c a t e d . These a r e d i s c u s s e d i n t h e s e c t i o n " I n t r u s i v e r o c k s " . A t t e n t i o n i s drawn t o t h a t group o f Lower M e s o z o i c r o c k s c o l l e c t i v e l y r e f e r r e d t o as t h e Vancouver group or i t s c o r r e l a t i v e . I t i s w i t h these r o c k s t h a t t h e known economic or sub-economic m a g n e t i t e bodies a r e a s s o c i a t e d and f o r t h i s r e a s o n the group i s b r i e f l y d e s c r i b e d below. Any one of t h e t h r e e u n i t s which comprise the Vancouver group, t o g e t h e r w i t h an a s s o c i a t e d i n t r u s i o n , may be h o s t to i r o n ore d e p o s i t s . ERA o o U J AGE VANCOUVER ISLAND T E X A D A ISLAND MORESBY ISLAND (QUEEN CHARLOTTE ISLANDS) O o 8 z UJ o Plioc. V I-UJ Mioc. Olig. Eoc. Paleoc. Metchosen volcanlcs Massett formation o o M o w UJ o o UJ -I 2 co o o < o Upper Middle Lower o CO CO < a: "3 Upper Middle Lower < Upper Middle Lower 5 CC U J a. z z UJ 0-Naniamo series Unnamed sequence of cong., s.st., coal }Bonanza group "I Quatsino form'n pncouver group Karmutsen group J Sutton formation Marble Bay formation Texada group Queen Charlotte group Longarm formation Wakoum formation Maude formation unconformity Kunga formation I 'Older volcanics —. — — unconformity — — — — • Sicker series •Anderson Bay formation Bedrock stratigraphy of Vancouver, Texada TABLE I and Moresby Islands, British Columbia - 1 6 -The Karmutsen group of v o l c a n i c r o c k s i s t h e o l d e s t member of the Vancouver group. The exposed t h i c k n e s s exceeds 1 0 , 0 0 0 f e e t a l t h o u g h i t s base has not been obser v e d (Mathews and McCammon, 195>7,P«35) • V o l c a n i c f l o w s , p r e d o m i n a n t l y b a s a l t and a n d e s i t e , a re c h a r a c t e r i s t i c of t h i s group. A m y g d a l o i d a l t e x t u r e s and p i l l o w l a v a s a r e common i n some areas but i n o t h e r s t h e r o c k i s e x t r e m e l y m a s s i v e . A l t e r a t i o n i s w i d e s p r e a d ; c h l o r i t e commonly r e p l a c e s f e r r o m a g n e s i a n m i n e r a l s and c a l c i t e , s e r i c i t e , - or e p i d o t e r e p l a c e s f e l d s p a r . F a i n t p i l l o w forms or f r a g m e n t a l t e x t u r e s a re i n many p l a c e s the o n l y r e m a i n i n g e v i d e n c e of a v o l c a n i c r o c k . Fragmental v o l c a n i c r o c k s a r e i r r e g u l a r l y d i s t r i -buted throughout the Karmutsen group. V o l c a n i c b r e c c i a s , both e x p l o s i v e and f l o w t y p e s , a r e more common than t u f f . A s s o c i a t e d w i t h t h e l a v a s and b r e c c i a s of the Karmutsen group a r e i r r e g u l a r b o d i e s , dykes, and s i l l s of i n t r u s i v e r o c k v e r y s i m i l a r i n c o m p o s i t i o n and appearance to the f l o w s . The r e l a t i o n i s n o t a b l e i n the v i c i n i t y of Benson Lake, Vancouver I s l a n d . Here, b o t h the i n t r u s i v e b o d i e s and the f l o w s a r e of s i m i l a r t e x t u r e , and i n a t l e a s t one l o c a l -i t y a dyke was seen to grade upward i n t o a f l o w or s i l l . T h i s would i n d i c a t e t h a t perhaps many dykes s e r v e d as f e e d e r s t o o v e r l y i n g f l o w s w h i c h were i n t u r n i n t r u d e d by l a t e r b o d i e s . - 1 7 -The upper p a r t of t h e Karmutsen group c o n s i s t s of b l a c k a r g i l l i t e and c r y s t a l l i n e l i m e s t o n e i n t e r b e d d e d w i t h l a v a s . F o s s i l s c o l l e c t e d from the a r g i l l i t e a r e of Upper T r i a s s i c age (Hoadley, 1 9 ^ 3»P« 1 7 )• Mathews found f o s s i l s i n d i c a t i v e of the K a r n i a n s t a g e o f the Upper T r i a s s i c i n t h e Texada p o r p h y r i t e s (Mathews and McCammon, 195>7»p»36). The Q u a t s i n o f o r m a t i o n t h a t c o n f o r m a b l y o v e r l i e s the Karmutsen group c o n s i s t s almost e n t i r e l y of l i m e s t o n e as much as I4.OOO f e e t t h i c k , f o r m i n g a co n s p i c u o u s marker i n the Vancouver group. The lower p a r t commonly i s i n t e r c a l a t e d , w i t h p y r o c l a s t i c m a t e r i a l or f l o w s but these d i m i n i s h upward i n t o r e l a t i v e l y pure w h i t e o r grey c r y s t a l l i n e l i m e s t o n e . Toward the top the l i m e s t o n e becomes d a r k e r and i s i n t e r -bedded w i t h a r g i l l i t e o f t h e o v e r l y i n g Bonanza group. Bedding, except where i t i s r e p r e s e n t e d by c o l o u r banding, i s g e n e r a l l y poor. C r o s s - b e d d i n g , t h r e e o r f o u r i n c h e s t h i c k , i n pure Q u a t s i n o l i m e s t o n e , was observed by the w r i t e r i n a r o a d - c u t near t h e Empire Development Company mine. F o s s i l s a r e g e n e r a l l y p o o r l y p r e s e r v e d i n the Q u a t s i n o f o r m a t i o n presumably because o f r e c r y s t a 1 1 i z a t i o n w hich i s common i n t h i s u n i t . Hoadley p l a c e d t h e age o f the upper p a r t o f t h e Qu a t s i n o l i m e s t o n e as " p r o b a b l y N o r i c " ( 1 9 5 3 , p . 2 1 ) , l a r g e l y because of s i m i l a r ages f o r t h e under -- 1 8 -l y i n g Karmutsen and o v e r l y i n g Bonanza groups. Limestones o c c u p y i n g a s i m i l a r s t r a t i g r a p h i c p o s i t i o n on Texada I s l a n d (Mathews and McCammon,19^7,p.36) and Moresby I s l a n d ( S u t h e r -land-Brown and J e f f e r y , I 9 6 0 , p . 2 ) have been i d e n t i f i e d as b e i n g of L a t e T r i a s s i c or E a r l y J u r a s s i c age. The Q u a t s i n o f o r m a t i o n grades upward i n t o t h e Bonanza group and t h e p o s i t i o n chosen as the top of the Q u a t s i n o i s a r b i t r a r y . Gunning ( 1 9 3 3 sP• 3U-) a n d Hoadley ( 1 9 3 5 * p.2 0 ) chose s l i g h t l y d i f f e r e n t h o r i z o n s t o accommodate mapping i n d i f f e r e n t l o c a l i t i e s . The Bonanza group may be d i v i d e d i n t o two p a r t s , a lower s e d i m e n t a r y d i v i s i o n and an upper v o l c a n i c d i v i s i o n . I n some areas t h e d i s t i n c t i o n i s not c l e a r . The t o p of the Bonanza group i s not known but Hoadley ( 1 9 5 3»P« 2 2 ) d e c i d e d t h a t i n the Bonanza Lake area t h e group i s " c e r t a i n l y more t h a n 3 2 0 0 f e e t t h i c k " . The s e d i m e n t a r y d i v i s i o n c o n s i s t s o f t h i n - b e d d e d sediments and i n t e r c a l a t e d l a v a f l o w s . The former c o n s i s t of carbonaceous l i m e s t o n e , c a l c a r e o u s a r g i l l i t e , a r g i l l i t e , and q u a r t z i t e . The v o l c a n i c d i v i s i o n i n c l u d e s a n d e s i t i c and b a s a l t i c f l o w s , v o l c a n i c b r e c c i a s , and banded t u f f s . I n t r u s i v e b o d i e s of i r r e g u l a r s i z e and shape t h a t o c c u r throughout p r o b a b l y s e r v e d as f e e d e r s f o r o v e r l y i n g f l o w s . The s e d i m e n t a r y u n i t o f t h e Bonanza group has been shown t o be of N o r i c age (mid-Upper T r i a s s i c ) and t h e v o l c a n i c assemblage i s thought t o be " p r o b a b l y J u r a s s i c " (Hoadley, 1 9 5 3 * p.29). On Moresby I s l a n d i n the Queen C h a r l o t t e s , t h e .Maude f o r m a t i o n u n c o n f o r n i a b l y o v e r l i e s t h e Kunga f o r m a t i o n which i s p r e d o m i n a n t l y l i m e s t o n e ( c o r r e l a t i v e of t h e Q u a t s i n o f o r m a t i o n ) * The Maude f o r m a t i o n p r o b a b l y reaches a maximum t h i c k n e s s o f '$000 f e e t . I t i s composed l a r g e l y o f s h a l e s and s i l t s t o n e s but the b a s a l p o r t i o n c o n t a i n s greywacke and con-g l o m e r a t e . The age I s thought t o he E a r l y J u r a s s i c which would c o r r e l a t e w i t h at l e a s t p a r t of t h e Bonanza group. S t r u c t u r e The e a r l i e s t r e c o r d e d t e c t o n i c event t o a f f e c t the Vancouver-Queen C h a r l o t t e - T e x a d a I s l a n d s area was t h e " C a s s i a r orogeny" w h i c h a p p r o x i m a t e l y marked the c l o s e o f t h e P a l e o z o i c e r a . T h i s orogeny was c h a r a c t e r i z e d by s t r o n g u p l i f t , n o r t h -w e s t - t r e n d i n g f o l d s , and u l t r a m a f i c i n t r u s i o n s . No u l t r a -m a f i c b o d i e s , however, have been found In the I n s u l a r Region of B r i t i s h Columbia (White, 1959,p.72) . -20-Much has been w r i t t e n about the s u c c e e d i n g t e c t o n i c a c t i v i t y , the Coast Range orogeny. White (195>9»P»78) d e s c r i b e d i t as "the most complex t e c t o n i c event i n the h i s t o r y of the Canadian C o r d i l l e r a , i n v o l v i n g r e g i o n a l f o l d i n g and f a u l t i n g , s t r o n g metamorphism, and a- p r o l o n g e d s u c c e s s i o n of g r a n i t i c i n t r u s i o n s " . I n d i c a t i o n s of the impending c a t a c l y s m , which p r o b a b l y c u l m i n a t e d i n the Lower C r e t a c e o u s , f i r s t appear i n the e a r l i e s t J u r a s s i c and. a c t i v i t y p e r s i s t e d , l o c a l l y at l e a s t , i n t o Upper C r e t a c e o u s . M e s o z o i c f o l d s west o f the Coast Range mountains c l o s e l y f o l l o w the d i r e c t i o n o f t h e mainland c o a s t . In. g e n e r a l , t h e Coast Range orogeny has produced o n l y m i l d d e f o r -m a t i o n among the c o a s t a l I s l a n d s . Open f o l d i n g o r broad arches are most common w i t h bedding d i p p i n g about I4.50 or l e s s . L o c a l l y , however, i t may be o v e r t u r n e d . M a j o r n o r t h w e s t - t r e n d i n g f a u l t s a r e known i n .south-ern Vancouver Island, and Moresby I s l a n d . The l a t t e r a r e des-c r i b e d as wrench f a u l t s i n which t h e P a c i f i c s i d e moved n o r t h ( S u t h e r l a n d - B r o w n and J e f f e r y , 1960,p .LL) . C o a s t Range orogeny was c l o s e l y followed, by t h e Rocky Mountain orogeny of Late C r e t a c e o u s - E a r l y T e r t i a r y t i m e . In g e n e r a l , t h i s t e c t o n i c a c t i v i t y d i d not a f f e c t the c o a s t a l -21-r e g i o n a l t h o u g h o f f i c e r s of the B.C. Department o f Mines have b r i e f l y mentioned a L a t e C r e t a c e o u s p e r i o d o f f o l d i n g on Moresby I s l a n d (Sutherland-Brown and J e f f e r y , I 9 6 0 , p.[}.) „ One or more epochs of f o l d i n g and normal f a u l t i n g which, t o o k p l a c e d u r i n g T e r t i a r y and Recent times i s c o l l e c t -i v e l y termed the "Puget orogeny". S e v e r a l i n t r u s i o n s on Vancouver I s l a n d , i n t h e G a r i b a l d i area of the Vancouver a r e a , and i n a d j a c e n t Washington s t a t e , a r e known t o c u t Upper Cr e t a c e o u s r o c k s . F o l d i n g developed a l o n g e a s t or sout h - e a s t t r e n d s and f a u l t movements o c c u r r e d a l o n g o l d as w e l l as new fau11 s. JL"trus i v e rocks Coast Range orogeny was marked by w h o l e s a l e i n t r u s i o n of p l u t o n i c r o c k s , c h i e f l y g r a n o d i o r i t e and q u a r t z d i o r i t e . Once c o n s i d e r e d to be a s i n g l e body and t h e r e f o r e termed t h e "Coast Range b a t h o l i t h " , t h e s e p l u t o n i c r o c k s now appear t o be a p r o d u c t of m u l t i p l e i n t r u s i o n s and are now known as the "Coast Range complex". Most i n t r u s i o n s are b e l i e v e d to be of L a t e J u r a s s i c or Cretaceous age. Some, such as t h e San C r i s t o v a l b a t h o l i t h of w e s t e r n Moresby I s l a n d , a re a p p a r e n t l y s y n t e c t o n i c and show we 1 1 - d e f i n e d p l a n a r s t r u c t u r e s . Other i n t r u s i o n s are c l e a r l y p o s t - t e c t o n i c . Most c o n t a c t metaso--22-m a t i c m a g n e t i t e d e p o s i t s are a s s o c i a t e d w i t h the l a t t e r t y p e . B a s i c s i l l s and dykes are common i n the v i c i n i t y of i r o n mines and a r e g e n e r a l l y p r e - o r e . A l a t e r , p o s t - o r e , s e t of l e u c o - d i o r i t e dykes i s e s p e c i a l l y prominent i n a r e a s of m a g n e t i t e m i n e r a l i z a t i o n . -23-CHAPTER I I - MINERALOGY AND GEOCHEMISTRY In t r u s i o n s I n t r u s i o n s a s s o c i a t e d w i t h m a g n e t i t e d e p o s i t s of Vancouver I s l a n d , Texada I s l a n d , and Moresby I s l a n d have been d e s c r i b e d by Swanson (1921].), Gunning (1930), Stevenson ( 1950), Hoadley (1953), S u t h e r l a n d - B r o w n and J e f f e r y ( i960), J e f f e r y (i960) .and Eastwood (1962) d u r i n g the cour s e o f r e g i o n a l map-p i n g i n these a r e a s . Quartz monzonite, g r a n o d i o r i t e , and qu a r t z d l o r i t e a r e t h e most common r o c k t y p e s . The w r i t e r c o l l e c t e d and s t u d i e d specimens of t y p i c a l g r a n i t i c r o c k s , f r e e of i n c l u s i o n s or ot h e r contamin-a n t s , t h a t a re a s s o c i a t e d w i t h i r o n ores o f the seven mines c o n s i d e r e d i n t h i s r e p o r t . The specimens were examined p e t r o g r a p h i c a 1 l y and c h e m i c a l , n o r m a t i v e , and modal a n a l y s e s made. The i n t r u s i o n s , i n g e n e r a l , are homophanous and have sharp c r o s s - c u t t i n g r e l a t i o n s w i t h c o u n t r y r o c k s . A c c o r d i n g t o the c l a s s i f i c a t i o n proposed by P e t e r s o n (1961), f i v e i n t r u s i o n s a re q u a r t z monzonite, one i s g r a n o d i o r i t e , and-one i s gabbro. These modes a r e shown i n F i g u r e 3 p l o t t e d Quartz Potash feldspar Plagioclase feldspar FIGURE 3 Modes of intrusions adjacent to magnetite deposits, British Columbia. Numbers refer to analyses, Toble 12 . Diagram ofter Johannsen, 1931. - 2 5 -on a Johannsen diagram, P l a g i o c l a s e , p o t a s h f e l d s p a r (some p e r t h i t i c ) , q u a r t z , and green hornblende a r e the ma i o r con-s t i t u e n t s of the i n t e r m e d i a t e v a r i e t i e s ; p l a g i o c l a s e and a u g i t e comprise the gabbro. Specimens of g r a n i t i c rock w i t h i n a few f e e t of t h e i r e x t e r n a l c o n t a c t s c o n t a i n a u g i t e r a t h e r than h o r n b l e n d e . O n l y one i n t r u s t i o n , the e a r l i e s t phase o f the G i l l i e s s t o c k , c o n t a i n s a u g i t e t h r o u g h o u t . L a t e r phases of t h i s s t o c k c o n t a i n h o r n b l e n d e . C h e m i c a l a n a l y s e s of specimens c o l l e c t e d from each of t h e seven i n t r u s i o n s s t u d i e d a r e g i v e n i n T a b l e 12 and are shown g r a p h i c a l l y i n F i g u r e b_. These ro c k s are a l l r i c h e r i n the group (Na20+K20+Al20-p)+Fe20^) than w o r l d averages of r o c k s r a n g i n g from g r a n i t e t o gabbro. The a n a l y s e s f a l l i n t o two d i v i s i o n s : one of i n t e r m e d i a t e c o m p o s i t i o n ( e n c i r c l e d by a d o t t e d l i n e , F i g . I4.) and one o f more b a s i c c o m p o s i t i o n (No. 3, gabbro from Coast Copper s t o c k ) . The a r i t h m e t i c a l average of the a n a l y s e s i n t h e f i r s t d i v i s i o n i s r e p r e s e n t e d by p o i n t 'X' i n F i g u r e l+. Some p l u t o n s a r e p a r t l y rimmed by a more b a s i c phase, p o s s i b l y as a r e s u l t o f c o n t a m i n a t i o n by l i m e s t o n e and/or v o l c a n i c c o u n t r y r o c k s . C o n t a c t e f f e c t s i n the c o u n t r y rock a r e most s t r i k i n g where metasomatic d e p o s i t s have formed; * endomorphism of the p l u t o n i s not as n o t i c e a b l e . Because FIGURE 4 Diagram showing compositions of intrusions adjacent to contact metasomatic magnetite deposits. Numbers refer to analyses, Table 12 Composition V is arithmetic average of analyses encircled hy the dotted line. World averages of the granite-gabbro series is also shown for comparison. - 2 7 -c o n t a c t metasomatic m a g n e t i t e d e p o s i t s are s p a t i a l l y , and p r o b a b l y g e n e t i c a l l y , r e l a t e d t o t h e s e p l u t o n s , i t i s important t o s t u d y the c h e m i c a l changes induced i n p l u t o n s by the c o u n t r y rocks they i n v a d e . The l a r g e s t c o n t r a s t s i n c h e m i c a l and p h y s i c a l p r o p e r t i e s of r o c k types a r e found, n e a r t h e margins of p l u t o n s and i t i s i n t h i s border zone t h a t c h e m i c a l a c t i v i t y w i l l be g r e a t e s t . The endomorphic e f f e c t s i n c e r t a i n p l u t o n s on Vancouver I s l a n d are d i s c u s s e d below. Some p l u t o n s are d i r e c t l y a s s o c i a t e d w i t h m a g n e t i t e d e p o s i t s whereas o t h e r s a r e not, a l t h o u g h a l l a re o f s i m i l a r c o m p o s i t i o n and invade s i m i l a r r o c k s , Hoadley (19.53) noted that q u a r t z d i o r i t e i n the Z e b a l l o s b a t h o l i t h has a border phase o f d i o r i t e and gabbro. The Nootka b a t h o l i t h i s g r a n i t e but near i t s c o n t a c t w i t h o l d e r v o l c a n i c r o c k s changes to s y e n o d i o r i t e or d i o r i t e i n a border zone 50 t o 100 f e e t wide. The approximate c h e m i c a l c o m p o s i t i o n o f Nootka g r a n i t e and the borde r phase d i o r i t e was c a l c u l a t e d from modes of these r o c k s (Hoadley, 1 9 5 3»P» 3 1 ) u s i n g m i n e r a l c o m p o s i t i o n and s p e c i f i c g r a v i t i e s g i v e n by Wahlstrom ( 1 9 5 5 ,PP . 8 8 , 8 9 ). The c o m p o s i t i o n of Bonanza group a n d e s i t e i s an average a n a l y s i s of t h r e e specimens of green a n d e s i t e from t h i s group (Hoadley, 1 9 5 3»P - 2 5 ). From a com-p a r i s o n of the s e c o m p o s i t i o n s ( T a b l e 2 ) , a rough e s t i m a t i o n of the endomorphic e f f e c t s i n the Nootka g r a n i t e i s p o s s i b l e . -28-T a b l e 2 Comparison of compos i t i c n s of Nootka g r a n i t e , i t s "contami n-a t e d " b o r d e r phase, and a n d e s i t e cou n t r y r o c k (from Hoad l e y , 1953). f Nootka g r a n i t e Border phase ( d i o r i t e ) Bonanza group a n d e s i t e S i 0 2 ,50.32 AlgO^ 17.1+ 17.2 Fe 20-j 0 . 0 8 7 . 2 2 3 . 8 i i FeO 0 . 0 9 9 . 6 7 8 . 0 5 ^Fe 0 . 1 3 1 2 . 6 0 8 . 9 5 CaO , 0 . 9 0 9 . 0 2 6 . 5 9 MgO .. 0.90 U-.98 1+.93 K 2 0 - 5 . 18 n e g l i g i b l e O .87 Na 20 . * 3 . 8 7 2 , 2 5 3 A 3 The most n o t a b l e c h e m i c a l changes accompanying " c o n t a m i n a t i o n " of Nootka g r a n i t e i s a decrease i n s i l i c a and po t a s s i u m and an i n c r e a s e i n t o t a l i r o n , c a l c i u m , and magnes ium. The Nimpkish i n t r u s t i o n s i n n o r t h e r n Vancouver I s l a n d a l l b e l o n g to t h e g r a n i t e c l a n ( g r a n o d i o r i t e , q u a r t z m onzonite, g r a n i t e ) e x cept f o r minor b a s i c phases (Hoadley, - 2 9 -1 9 5 3,PP.2 9 - 3 0 ). The E h a t i s h a t b a t h o l i t h i s a l s o o f the g r a n i t e c l a n and has a more b a s i c b o r d e r zone ( I b i d , p . 3 2 ) . Eastwood (1 9 6 2 ,pp.1 1 8 - 1 1 9) noted t h a t g r a n o d i o r i t e i n an un-named b a t h o l i t h i n t h e Kennedy Lake area grades i n t o d i o r i t e near i t s c o n t a c t w i t h l i m e s t o n e and t u f f . In h i s study of the g e o l o g y of t h e Cowichan Lake a r e a , Vancouver I s l a n d , F y l e s (1955) found t h a t t h e S a a n i c h g r a n o d i o r i t e p l u t o n changes t o a b o r d e r zone of q u a r t z d i o r i t e where i t i n t r u d e s b a s a l t i c c o u n t r y rock. T h i s border phase i s u s u a l l y s e v e r a l tens of f e e t and l o c a l l y more th a n a hundred f e e t wide. A t r a n s i t i o n a l r o c k , r e p r e s e n t i n g a h i g h l y a l t e r e d phase of t h e b a s a l t , i s found between q u a r t z d i o r i t e and b a s a l t . A n a l y s e s o f t h e fo u r r o c k s g r a n o d i o r i t e , q u a r t z d i o r i t e , t r a n s i t i o n a l r o c k , and b a s a l t , show t h e c h e m i c a l changes a c r o s s the m a r g i n a l zone o f t h i s p l u t o n where i t i s i n c o n t a c t w i t h v o l c a n i c r o c k . These a n a l y s e s a re shown i n T a b l e 3 . In t h e m a r g i n a l zone o f S a a n i c h g r a n o d i o r i t e t h e r e i s a r e l a t i v e g a i n of i r o n , aluminum, magnesium, and c a l c i u m and a r e l a t i v e l o s s o f s i l i c a and p o t a s s i u m . Those elements t h a t show a dec r e a s e i n border g r a n i t i c r o c k a p p a r e n t l y en-r i c h c o n t i g u o u s a l t e r e d b a s a l t . T h i s i s shown by comparing the c o m p o s i t i o n of t h e t r a n s i t i o n r o c k w i t h t h a t of the - 3 0 -T a b l e 3 A n a l y s e s showing changes aeross t h e c o n t a c t o f S a a n i c h  g r a n o d i o r i t e and b a s a l t (from F y l e s , 1955)-S a a n i c h g r a n o d t . Border phase ( q t z . d i o r i t e ) T r a n s i t i o n a l r o c k ( a l t e r e d b a s a l t ) Amygdalo i d a l b a s a l t S i 0 2 67.5% 61 . 1 $ 50.9% 50.1% A 1 2 0 3 Ui.. 9 16.7 15 .0 12.2 Fe2C>3 1.59 2 . 8 3 3-53 3 . 3 9 FeO 2 . 1 5 3 .21 1+.92 5 . 3 3 £Fe 2 . 7 8 L+.L+8 6.29 6.1+3 MgO 1.61 2.1+3 7.69 , 9 . 8 3 CaO 3-52 1+.92 9 . 1 8 11 . 8 Na 20 3 . 3 2 3 .71 2 . 3 5 2.1+2 K 20 3 . 2 8 2 . 1 5 1.76 0 . 8 8 b a s a l t ( T able 3 ) . Both Nootka and S a a n i c h s t o c k s have r e -l a t i v e l y g a i n e d much i r o n i n t h e i r border zones a d j a c e n t t o v o l c a n i c r o c k s . N e i t h e r s t o c k i s a s s o c i a t e d w i t h any known m a g n e t i t e d e p o s i t s but t h e S a a n i c h border zone c o n t a i n s con-s i d e r a b l y more i r o n t h a n the average S a a n i c h g r a n o d i o r i t e . A c i d i c i n t r u s t i o n s i n c o n t a c t w i t h b a s i c v o l c a n i c r o c k have co n t a m i n a t e d b o r d e r zones as much as 100 f e e t t h i c k . -31-These border zones a r e absent around gabbro I n t r u s i o n s . ( e , g . • some phases of the Z e b a l l o s b a t h o l i t h (Stevenson,19^0,p.27) or p a r t s of t h e Coast Copper s t o c k ) . C o n t a c t s w i t h l i m e s t o n e are more r e g u l a r than c o n t a c t s w i t h v o l c a n i c rocks and endo-morphism i s l e s s i n t e n s e . Hoadley (195>3»p.33) noted t h a t r o c k of the P e r r y Lake s t o c k o n l y t e n f e e t from a c o n t a c t w i t h Q u a t s i n o l i m e s t o n e i s almost i d e n t i c a l i n c o m p o s i t i o n t o the average g r a n i t e o f the s t o c k . The I n t e r v e n i n g c o n t a m i n a t e d zone i s d a r k e r than the u n a l t e r e d g r a n i t e . From Hoadley's modes of the two r o c k t y p e s the approximate c h e m i c a l c o m p o s i t i o n s of t h e s e r o c k s have been c a l c u l a t e d (Table )+) , In the b o r d e r phases of both t h e S a a n i c h and Nootka i n t r u s i o n s s i l i c a shows a r e l a t i v e d e c r e a s e whereas a r e l a t i v e i n c r e a s e of t h i s element i s i n d i c a t e d i n t h e P e r r y Lake s t o c k . The c h e m i c a l c o m p o s i t i o n s both of i n t e r i o r and b o r d e r phases o f t h e P e r r y Lake s t o c k and t h e G i l l i e s s t o c k a re com-pared i n T a b l e s Ij. and 5>. Both s t o c k s i n t r u d e l i m e s t o n e but the former has no known nearby m a g n e t i t e d e p o s i t s whereas the l a t t e r i s a s s o c i a t e d w i t h s e v e r a l commercial m a g n e t i t e d e p o s i t s . The i r o n c o n t e n t o f the G i l l i e s s t o c k b o r d e r zone, as i s t h e P e r r y Lake m a r g i n a l r o c k , i s p r a c t i c a l l y n i l yet s k a r n o n l y a few f e e t from the G i l l i e s s t o c k c o n t a i n s a p p r o x i m a t e l y 20?? t o t a l i r o n and t h e a d j a c e n t o re zone 6j>%, - 3 2 -T a b l e II C o m p o s i t i o n of P e r r y Lake g r a n i t e and a s s o c i a t e d border phase  i n c o n t a c t w i t h l i m e s t o n e (from Hoadley, 19.53) • P e r r y Lake g r a n i t e Border phase S i 0 2 66.8f 0 75.7% A I 2 O 3 15.5 11.7 F e 2 0 3 1,214. 0 . 2 5 FeO 1.63 0.31 £Fe 2 . 11+ 0.I4.I MgO 3 . 2 7 2 . 8 2 CaO [4.I4.O 0 , 7 6 Na 2 0 2 , 9 3 0 . 7 3 K 2 0 3 . 2 2 7 . 5 5 I r o n , magnesium, and sodium a re r e l a t i v e l y d e p l e t e d i n t h e border phases o f both t h e P e r r y Lake and G i l l i e s s t o c k s . S i l i c a , aluminum, c a l c i u m , and p o t a s h , on t h e o t h e r hand, do not show c o n s i s t e n t t r e n d s i n the two s t o c k s ; aluminum and c a l c i u m a re r e l a t i v e l y e n r i c h e d and s i l i c a and potassiu m d e p l e t e d i n the G i l l i e s s t o c k b o r d e r phase. In the P e r r y Lake border phase, t h e s e trends a r e r e v e r s e d . -33-T a b l e 5 G i l l i e s s t o c k q u a r t z monzonite and a s s o c i a t e d border phase. In c o n t a c t w i t h l i m e s t o n e a d j a c e n t t o the P r e s c o t t orebody, Texada I s l a n d . ( A n a l y s e s by R.M. S t a f f and A.V. Payne, G e o l o g i c a l S u r v e y , Canada). Q u a r t z monzonite Border phase S i 0 2 55.6% 1+6.3% A I 2 O 3 19.1; 2 6 . 5 F e 2 0 3 3.6 1.1 FeO 3.3 1.1 £Fe 5.1 1.6 MgO 3.1 2 . 2 CaO 7.0 11 . 5 Na 20 3.6 2J4. K 2 0 2 . 2 1.8 A d e t a i l e d s t u d y of t h e d i s t r i b u t i o n o f c e r t a i n elements was made i n t h e margins o f the Coast Copper s t o c k a d j a c e n t t o the Empire Development Company d e p o s i t s . T h i s s t o c k was s e l e c t e d because the c o n t a c t i s l o c a l l y w e l l exposed, o u t c r o p s a r e p l e n t i f u l , and t h e r o c k appears f r e s h i n handspecimen. Five-pound c h i p samples were c o l l e c t e d at -3)+-each of 22 s t a t i o n s at a p p r o x i m a t e l y 100 f o o t i n t e r v a l s a l o n g two l i n e s . These l i n e s began a t or near the c o n t a c t o f Coast Copper gabbro and Bonanza group v o l c a n i c r o c k s and extended r o u g h l y p e r p e n d i c u l a r t o t h i s c o n t a c t f o r s e v e r a l hundred f e e t toward the i n t e r i o r of t h e i n t r u s i o n . N ine samples were c o l -l e c t e d a l o n g T r a v e r s e 'A' a d j a c e n t to the M e r r y Widow d e p o s i t ; 13 samples were c o l l e c t e d a l o n g T r a v e r s e 'B' which was p a r a l l e l t o 'A' but 1000 f e e t f a r t h e r south and remote from any known m i n e r a l i z e d zone. The r e l a t i o n s a re shown i n F i g u r e 5« The samples were a n a l y z e d s p e c t r o g r a p h i c a 1 l y f o r the f e r r i d e elements (Mn,V,Ti,Ni,Co,Cr, and Fe) and f o r copper. Weight p e r c e n t m a g n e t i t e i n each sample v/as a l s o d e t ermined and t h e r e s u l t s r e c a l c u l a t e d to w eight p e r c e n t i r o n . Thus a c l e a r d i s t r i n c t i o n was made between t o t a l i r o n ( F e t ) and i r o n i n m a g n e t i t e ( F e m ) . R e s u l t s o f these a n a l y s e s are g i v e n i n T a b l e 6. V a l u e s f o r T i , N i , and Cr a r e t o o i n c o n s i s t e n t t o attempt to c o r r e l a t e w i t h d i s t a n c e from t h e c o n t a c t . The method of l e a s t squares was used, to f i t a s t r a i g h t l i n e t o v a l u e s f o r V, Mn, Co, and Cu. In both t r a v e r s e s , however, the c o r r e l a t i o n c o e f f i c i e n t f o r t h e s e elements was l e s s t h a n 0 . 5 . A " p e r f e c t f i t " would have a c o r r e l a t i o n c o e f f i c i e n t of 1.0. A c o e f f i c i e n t l e s s than 0 .5 means t h a t v a r i a t i o n s i n V, Mn, -35-EMPIRE DEVELOPMENT CO. LTD LOCAL GEOLOGY (Compiled by Company geologists) S C A L E - l"*500' Coast Copper stock - gabbro* diorite Bonanza group I?)- intrusive andesite Bonanza group- tuffs j andesite flows Quatsino formation- limestone Massive magnetite Mixed magnetite and andesite FIGURE 5 I - 3 6 -T a b l e 6 S p e c t r o g r a p h i c a n a l y s e s of gabbro i n T r a v e r s e s ' A ' and 1 B 1 , Coast Copper s t o c k . ( A n a l y s t , W.F. White, G e o l . Survey, Canada) D i s t . from con-t a c t ( f e e t ) Samp 1e number % Mn % V % T i * % Ni % Co a) Cr % F e t % F em % Cu 55 iLj.0 255 31+o 395 1+50 6 1 0 700 7 8 0 15 80 160 250 325 390 1+1+0 51+0 6 0 0 6 8 0 71+0 820 870 T r a v e r s e ' A ' 1 2 3 k 5 6 7 8 9 T r a v e r s e 1 2 3 1+ 5 6 7 8 9 10 11 12 13 > 0 . 12 0.11 0 . 11 0 . 1 6 0.17 0 . 1 3 0 . 1 5 0 .19 0 , 2 0 • 0.17 0 . 1 5 0 . 1 5 0 . 0 9 8 0 . 12 0 . 1 5 0.17 0 . 1 5 0 . 2 0 0 . 1 1 0 . 2 0 0.17 0 , 2 0 0.01+2 0 . 0 3 7 0 , 0 8 6 0 . 0 9 2 0 . 0 6 8 0 . 0 6 7 0.01+1+ 0 . 0 3 0 0 . 0 1 6 0.01+8 0.01+3 0,071+ 0,01+1 0.01+9 0 , 0 5 8 0 . 0 7 2 0 . 0 6 7 0.081+ 0 . 0 5 0 0 , 0 6 3 0 . 0 3 3 o.oi+o 1.6 0 . 9 9 > 2 . 0 >2.0 72.0 >2.0 >2.0 >2.0 72 .0 1.8 1.7 >2.0 1.0 >2.0 1.5 >2.0 1.9 >2.0 1.1+ >2,0 >2.0 1.6 NF ti it tt it I! II II II NF it ti 11 II it 0 , 0 1 3 NF 11 11 n 11 ti 0.001+3 0 . 0 0 3 5 0 . 0 0 5 8 0 . 0 0 7 2 NF 0 . 0 0 3 7 O.OO5.I 0.001+6 NF 0 . 0 0 5 0 NF 0 . 0 0 6 8 0 . 0 0 5 3 O.OO69 0.001+9 NF 0 . 0 0 5 7 0 . 0 0 6 1 0 . 0 0 3 6 0 . 0 0 3 9 CO. 002 0 . 0 0 6 5 0.001+9 <0.003 NF <0.003 NF 0.0071+ <0.003 0 . 0 0 7 1 0 . 0 0 3 1 NF 8.1+ 6 . 7 l l . l 11 .2 8 . 3 9 . 2 10.1+ 8 . 5 9 . 0 8 . 8 10 .8 6.1+ 9 . 0 ' 8 . 7 10 .8 7.6 12.7 7 . 6 12.2 10.2 8 . 5 1.6 3 . 2 3 . 8 5 . 9 3 . 9 1.0 '+.!+ 3 . 6 1.5 3 . 7 3 .1 7 . 2 3 . 3 2 . 0 3 . 5 5 .7 \S 1+.0 1+.7 3 . 2 1 .8 0.0061+ NF 0 . 0 2 2 0 . 0 1 5 0 . 0 0 6 9 <0.002 0 . 0 0 5 0 0 . 0 0 5 9 0 . 0 0 5 8 0 . 0 0 5 0 0 . 0 0 3 9 0 . 0 1 6 NF 0 . 0 1 0 0 . 0 0 2 9 0 . 0 0 9 6 0 . 0 0 3 3 0 . 0 1 3 NF 0 . 0 1 3 0.001+2 0.0037 -::-Values f o r T i are s e m i - q u a n t i t a t i v e o n l y . Upper l i m i t of method a p p r o x i m a t e l y 2%. -37-Co, and Cu cannot be f i t t e d t o a s t r a i g h t l i n e r e l a t i n g t h e s e v a l u e s t o d i s t a n c e from the c o n t a c t i . e . , t h e r e i s no s t a t i s t -i c a l change i n t h e c o n c e n t r a t i o n s of these elements away from the c o n t a c t . In f i t t i n g a s t r a i g h t l i n e curve (y = a+bx) t o v a l u e s of t o t a l i r o n ( F e ^ ) , however, a c o r r e l a t i o n c o e f f i c i e n t of 0.81j.was o b t a i n e d i n . T r a v e r s e 'A' and 0.67 i n T r a v e r s e 'B'. These c o e f f i c i e n t s show t h a t v a l u e s of Fe^. and d i s t a n c e from the c o n t a c t can be f i t t e d to a s t r a i g h t l i n e . These v a l u e s are shown i n F i g u r e 6a. The i n t e r c e p t i n both t r a v e r s e s i s 8.5% F e t but t h e s l o p e s of the l i n e s are s m a l l : 0.0017 In 'A' and 0.0021 i n 'B'. A s t a t i s t i c a l t e s t ( S t u d e n t ' s " t " d i s -t r i b u t i o n ) showed t h a t such s l o p e s are not s i g n i f i c a n t l y d i f f e r e n t from z e r o and t h e r e f o r e the average v a l u e o f Fe^ does not v a r y s i g n i f i c a n t l y from 8.5% at any d i s t a n c e from the i n t r u s i v e c o n t a c t i n e i t h e r t r a v e r s e i . e . a l t h o u g h t h e v a l u e s can be f i t t e d to a s t r a i g h t l i n e , t h i s l i n e has a z e r o s l o p e . The z e r o s l o p e of t h e s e l i n e s shows t h a t gabbro of the Coast Copper s t o c k i n t h i s a rea has no s i g n i f i c a n t v a r i a t i o n i n i r o n c o n t e n t from the b o r d e r zone ( i n c o n t a c t w i t h v o l c a n i c r o c k s ) t o t h e i n t e r i o r of the s t o c k up t o 800 f e e t from the c o n t a c t . F u r t h e r m o r e , because t h e r e i s no s i g n i f i c a n t d i f f e r e n c e i n i r o n content o f the s t o c k a d j a c e n t Traverse 'A' O O O O Traverse'B' 4* 4" 4" 4" 13 -12 -II -^ 10-| u - e -7 -6 -5 + + 100 200 o 4 4-300 4 4-400 500 Distance from contact in feet FIGURE 6a 4-600 4-o 4-700 4-800 4-900 ^0.5 R-4-4 0 4- o 4-4v 4-4-1 _L 4-o o 4- -I-o 4-100 200 300 40O 500 Distance from contact in feet FIGURE 6b 600 700 800 FIGURE 6 Coast Copper stock, Vancouver Island. Graphs showing variations in total iron content (Fef)(Fig. 6a) and in the ratio of iron in magnetite (Fem) to total Iron. For locations of traverses, see Figure 5. - 3 9 -t o the M e r r y Widow d e p o s i t ( T r a v e r s e 'A") as compared t o a p l a c e remote from the i r o n d e p o s i t ( T r a v e r s e 'B'), suggests t h a t m a g n e t i t e of t h e s t o c k e v i d e n t l y i s g e n e t i c a l l y u n r e l a t e d to m a g n e t i t e of a d j a c e n t o r e b o d i e s . A l i n e whose s l o p e i s zero i s a l s o i n d i c a t e d i n the p l o t of F e m / F e t v e r s u s d i s t a n c e ( F i g u r e 6 b ) . T h i s means t h a t t h e m a g n e t i t e c o n t e n t of the s t o c k does not change, r e l a t i v e to t o t a l i r o n , whether o r not i t i s i n r o c k a d j a c e n t t o t h e M e r r y Widow d e p o s i t . M a g n e t i t e c o n s t i t u t e s between 1 and 11 w e i g h t p e r c e n t of the Coast Copper gabbro i n t h i s a r e a . I t r e p l a c e s a u g i t e , the o n l y o t h e r major i r o n - b e a r i n g m i n e r a l . Without f u r t h e r e v i dence t h e r e i s no way of knowing whether such m a g n e t i t e formed as a l a t e magmatic m i n e r a l from t h e melt w h i c h produced the gabbro or whether i t has r e p l a c e d pyroxene as a r e s u l t of a l a t e r p e r i o d o f i r o n metasomatism, such as t h a t which formed the nearby M e r r y Widow and K i n g f i s h e r m a g n e t i t e d e p o s i t s . M a g n e t i t e i n f o u r samples from the gabbro has a t i t a n i u m con-t e n t r a n g i n g from 5 . 6 t o 8.1+% T i . In c o n t r a s t , one sample from the K i n g f i s h e r d e p o s i t c o n t a i n s no t i t a n i u m and m a g n e t i t e from a n o t h e r s m a l l d e p o s i t i n t h e area a n a l y z e d 0.0071+% T i . The c o n t r a s t i n t i t a n i u m c o n t e n t of a c c e s s o r y and ore m a g n e t i t e suggest d i f f e r e n t c o n d i t i o n s of f o r m a t i o n . Buddington et a l . (1955) showed t h a t T i - r i c h m a g n e t i t e s a r e c h a r a c t e r i s t i c of rocks formed d i r e c t l y from a melt at h i g h temperature and t h a t , -1+0-i n t hese c a s e s , m a g n e t i t e formed as a p r i m a r y d i f f e r e n t i a t e . P e g m a t i t e s , on the o t h e r hand, were shown by the same au t h o r s t o c a r r y T i - p o o r m a g n e t i t e . I t i s p o s s i b l e , t h e r e f o r e , t h a t m a g n e t i t e i n t h e Coast Copper gabbro was produced as a l a t e magmatic m i n e r a l and m a g n e t i t e i n the o r e b o d i e s as a l a t e r h y d r o t h e r m a l m i n e r a l . The c o n s i s t e n t F e m / F e ^ r a t i o shows t h a t as t h e m e l t c o o l e d and began t o c r y s t a l l i z e , a f i x e d p r o p o r t i o n of i r o n was t a k e n up as a u g i t e and the remainder formed m a g n e t i t e which t h e n , In p a r t , r e p l a c e d e a r l i e r - f o r m e d a u g i t e . V o l c a n i c r o c k s Of m a g n e t i t e depos i t s t h a t a r e i n v o l c a n i c r o c k s , most a r e i n the Karmutsen group or i t s c o r r e l a t i v e . A n a l y s e s of t h r e e v o l c a n i c rocks from t h i s group a r e g i v e n i n T a b l e 13 and a r e shown g r a p h i c a l l y i n F i g u r e 7 . Average i r o n c o n t e n t of t h e s e Karmutsen rocks i s 7 . 9 0 % . The c o m p o s i t i o n o f t h e s e rocks i s not s i g n i f i c a n t l y d i f f e r e n t from w o r l d averages of a n d e s i t e and b a s a l t (Nocko 1 ds , 195'-+) • Two d e p o s i t s , M e r r y Widow and F.L., occur i n p y r o c l a s t i c s and f l o w s of the Bonanza group. Two c h e m i c a l a n a l y s e s of Bonanza t u f f s are g i v e n by Stevenson (195>0,pp. 2 0 - 2 1 ) ; average i r o n c o n t e n t o f these r o c k s i s 8 . 3 % . Red and green s i l i c e o u s t u f f s a r e i n t e r c a l a t e d w i t h f l o w s and - l + l -s e d i m e n t a r y m a t e r i a l on T a h s i s M o u n t a i n , Z e b a l l o s map-area, and an a n a l y s i s of green t u f f i s g i v e n by H o a d l e y ( 1 9 5 3 » p 2 6 ) . He d i v i d e d the flows i n t o two broad g r o u p s , r e d a n d e s i t e s and green a n d e s i t e s . Two a n a l y s e s o f t h e red and t h r e e o f the green a n d e s i t e show t h a t t h e r e d have a h i g h e r f e r r i c : f e r r o u s i r o n r a t i o , a c o n d i t i o n w h i c h t h e red c o l o u r would s u g g e s t . Average i r o n c o n t e n t of r e d a n d e s i t e i s 6.2lp% and o f t h e green, 8.95% (Hoadley, 1 9 5 3 , p . 2 5 )- A specimen of Bonanza group a n d e s i t e from the F.L. mine a r e a has an i r o n c o n t e n t o f 7 .6% (see a n a l y s i s 3 , T a b l e 1 3 ) ' T h i s a n a l y s i s i s shown graph-i c a l l y i n F i g u r e 7 (no. 3 ) . An a n a l y s i s of green a n d e s i t e c o l l e c t e d by t h e p r e s e n t w r i t e r from t h e Bynnor mine a r e a , t e n t a t i v e l y c o r r e l a t e d w i t h the Bonanza group (Eastwood, 1 9 6 2 , p.113) , has a t o t a l i r o n c o n t e n t o f 7 . 2 9 % (No. 2 , F i g . 5 ) . Limest one Limestone o f the Q u a t s i n o f o r m a t i o n , or i t s c o r -r e l a t i v e , i s a s s o c i a t e d w i t h a l l known C o a s t a l B r i t i s h Columbia economic m a g n e t i t e d e p o s i t s . T h i s u n i t i s c h a r a c t e r -i z e d by i t s (1) massive n a t u r e ( 2 ) w i d e s p r e a d r e c r y s t a 1 1 i z a t i o n (3) h i g h p u r i t y and (1L) s c a r c i t y of f o s s i l s . C h e m i c a l a n a l y s e s (Table 111) show t h a t such l i m e s t o n e i s more than 85% CaCO-^. Near some g r a n i t i c i n t r u s t i o n s , d o l o m i t i z a t i o n of l i m e s t o n e WORLD AVERAGES (Nockolds, 1954) FIGURE 7 Diagram showing compositions of volcanic rocks associated with contact metasomatic magnetite deposits. Numbers refer to analyses, Table 13. -1+3-has been r e c o g n i z e d (Stevenson, 1 9 5 0 ,p. 1 7 ) and i n the Brynnor mine magnesium metasomatism, i n t h e form of s e r p e n t i n e , has i n c r e a s e d l o c a l l y t he magnesia c o n t e n t of t h e a s s o c i a t e d l i m e s t o n e . A l s o , the upper p a r t of the M a r b l e Bay f o r m a t i o n on Texada I s l a n d i s magnesium-rich (Mathews and McCammon,1957, pp.5 2 - 5 5 ) . No known m a g n e t i t e d e p o s i t s o c c u r , however, i n d o l o m i t e , d o l o m i t i c l i m e s t o n e , or magnesian l i m e s t o n e . Other i m p u r i t i e s , such as alu m i n a and i r o n , a r e n e g l i g i b l e . S k a r n The o r i g i n a l meaning of the t e r m s k a r n i s l o s t i n a n t i q u i t y . L I n d g r e n ( 1933j ip.705) mentioned t h a t i t .-Is an o l d Swedish m i n i n g term f o r t h e g a r n e t - p y r o x e n e - e p i d o t e r o c k accompanying many S c a n d i n a v i a n m a g n e t i t e d e p o s i t s . The American G e o l o g i c a l I n s t i t u t e G l o s s a r y (1957) d e f i n e s s k a r n as " a r o c k n e a r l y e n t i r e l y composed of l i m e - b e a r i n g s i l i c a t e s and d e r i v e d from n e a r l y pure l i m e s t o n e s and d o l o m i t e s i n t o w h i c h l a r g e amounts of S i , A l , Fe, and Mg have been i n t r o d u c e d " . T a c t i t e has been suggested f o r t h o s e skarns of c o n t a c t metamorphic o r i g i n (Hess, 1 9 1 9 ; S c h m i t t , 191+8) . These d e f i n i t i o n s , however, a r e u n s a t i s f a c t o r y i n t h a t many skarns are d e r i v e d from r o c k s other than l i m e s t o n e s and d o l o m i t e s . Shaw (1957) noted t h a t the m i n e r a l o g y of skarns i s complex and t h a t some a r e of c o n t a c t metamorphic o r i g i n , some are caused by s i m p l e metamorphism, some a r e metasomatic, and some are v e i n s . He r e f e r r e d to s k a r n as "a r o c k c o n s i s t i n g m a i n l y of lime s i l i c a t e s w i t h or w i t h o u t c a r b o n a t e s and commonly con-t a i n i n g m a g n e t i t e or other i r o n - h e a r i n g m i n e r a l s " . T h i s d e f i n i t i o n cannot be a p p l i e d r i g o r o u s l y because to do so would i n c l u d e r o c k s such as m a g n e t i t e - b e a r i n g a n o r t h o s i t e s , h o r n -b l e n d i t e s , and o t h e r rocks not n o r m a l l y c o n s i d e r e d to be s k a r n s . M i n e r a l s such as g a r n e t , d i o p s i d e , h e d e n b e r g i t e , e p i d o t e , i l v a i t e , v e s u v i a n i t e , e t c . a r e common c o n s t i t u e n t s o f skar n s and i n t h i s r e p o r t these m i n e r a l s c o n s t i t u t e 80% or more of the r o c k r e f e r r e d t o as s k a r n . The r e m a i n i n g 20% may be u n r e p l a c e d host r o c k or oth e r n o n - c a l c i u m - s i l i c a t e m i n e r a l s . V a r i o u s a d j e c t i v e s , used i n c o n j u n c t i o n w i t h t h e term s k a r n , i d e n t i f y s k a r n of a p a r t i c u l a r m i n e r a l c o m p o s i t i o n (e.g. g a r n e t -s k a r n , e p i d o t e - s k a r n , e t c . ) . The author proposes t h a t the p r o c e s s by w h i c h s k a r n i s formed be c a l l e d s k a r n i f i c a t i o n i . e . t h e replacement by, c o n v e r s i o n I n t o , or I n t r o d u c t i o n o f s k a r n . The term i s analogous t o o t h e r s such as g r a n i t i z a t i o n , c h l o r i t i z a t i o n , s e r i c i t i z a t i o n , e t c . The term would i n c l u d e a l l p r o c e s s e s by w h i c h s k a r n may be formed such as c o n t a c t metamorphism, c o n t a c t metasomatism, or r e g i o n a l metamorphism. Skarn i n western B r i t i s h Columbia m a g n e t i t e d e p o s i t s -45-i s m i n e r a l o g i c a 1 l y and c h e m i c a l l y s i m p l e . Four phases, g a r n e t , pyroxene, e p i d o t e , and m a g n e t i t e comprise more than 95% by volume o f s k a r n . Chemical a n a l y s e s f u r t h e r show t h a t seven compenents, CaC, FeO, F e 2 0 ^ , S i 0 2 , A l 2 O y MnO, and MgO comprise more t h a n 95% (by we i g h t ) of two samples of t y p i c a l s k a r n (Table 15)• The number o f phases, t h e r e f o r e , i s not more t h a n the number o f components. T h i s c o n f o r m i t y t o the M i n e r a l o g i c a l Phase Rule s u g g e s t s , a l t h o u g h i t does not prove, t h a t e q u i l i b r i u m was r e a c h e d d u r i n g f o r m a t i o n o f s k a r n . Water, car b o n d i o x i d e , oxygen, and oth e r v o l a t i l e s a r e c o n s i d e r e d t o be p e r f e c t l y m o b i l e components. A number of r o c k types have been r e p l a c e d by s k a r n i n t h e area c o n s i d e r e d by t h i s s t u d y . The volume of a n d e s i t e , b a s a l t , and t u f f a c e o u s r o c k s which have been a l t e r e d to skarn p r o b a b l y exceeds the volume of a l l o t h e r r o c k types combined, i n c l u d i n g l i m e s t o n e . D e p o s i t s i n v o l c a n i c r o c k s are commonly e n c l o s e d i n a wide s k a r n zone e x t e n d i n g outward from t h e c e n t r a l ore zone as i r r e g u l a r tongues, s h o o t s , or p a t c h e s . D e p o s i t s i n l i m e s t o n e , i n c o n t r a s t , a re s u r r o u n d e d by o n l y a narrow r i m of s k a r n . Where p l u t o n i c r o c k s o c c u r a d j a c e n t t o ma g n e t i t e d e p o s i t s , t h e y t o o are r e p l a c e d , t o a minor e x t e n t , by s k a r n . In most c a s e s , s k a r n i f i c a t i o n has o b l i t e r a t e d -46-t e x t u r e s and s t r u c t u r e s o r i g i n a l l y p r e s e n t i n the h o s t r o c k so t h a t i t i s d i f f i c u l t t o determine w i t h c e r t a i n t y what ro c k has been r e p l a c e d . The homogeneous n a t u r e of s k a r n i s p r o b a b l y l a r g e l y caused by t h e massive t e x t u r e and s t r u c t u r e o f the host r o c k s . Karmutsen v o l c a n i c s , Q u a t s i n o l i m e s t o n e , and g r a n i t i c p l u t o n s a r e a l l l o c a l l y homophanous and o f homogeneous compos-i t i o n . Some s m a l l - s c a l e i n h o m o g e n e i t i e s however, do occur i n th e s e rocks and even t h e s e h e t e r o g e n e i t i e s have been c o m p l e t e l y t r a n s f o r m e d i n t o massive red-brown garnet s k a r n w h i c h i s m a c r o s c o p i c a l l y i d e n t i c a l w i t h t h a t formed by replacement of o t h e r homogeneous r o c k s . Examples o f such i n h o m o g e n e i t i e s a r e a p l i t e dykes i n t h e G i l l i e s s t o c k and bedded t u f f i n the M e r r y Widow and Brynnor mines. In s p i t e o f t h e o b l i t e r a t i n g e f f e c t of s k a r n i f i c a t i o n , c e r t a i n f e a t u r e s i n some skarns have been r e c o g n i z e d as o c c u r -r i n g more or l e s s c o n s i s t e n t l y w i t h p a r t i c u l a r r o c k t y p e s . For example, s k a r n i f i c a t i o n of a p h a n i t i c r o c k s , p a r t i c u l a r l y dykes or f l o w s , u s u a l l y has r e s u l t e d i n a f i n e - g r a i n e d compact s k a r n . There i s a g e n e r a l tendency f o r such s k a r n t o c o n t a i n a r e l a t i v e l y l a r g e p r o p o r t i o n o f pyroxene and/or e p i d o t e , r a t h e r than g a r n e t . S k a r n formed i n l i m e s t o n e , i n c o n t r a s t , i s medium- or c o a r s e - g r a i n e d and vuggy. These vugs a r e f i l l e d w i t h c a l c i t e , s u l p h i d e s , q u a r t z o r , near the ore zones, m a g n e t i t e . Garnet i s t h e predominant m i n e r a l i n . s k a r n of I -1+7-t h i s t y p e . Where s k a r n i f i c a t i o n has a l t e r e d p l u t o n i c r o c k s , the g r a n i t i c t e x t u r e o f the h o s t i s r e t a i n e d i n ro c k s b o r d e r -i n g the massive s k a r n zone ( P l a t e s I I and X V I I ) . In such border zones, s e c o n d a r y c a l c - s i 1 i c a t e m i n e r a l s form o n l y 20-30% of t h e b u l k c o m p o s i t i o n and the r o c k cannot p r o p e r l y be c l a s s i f i e d as s k a r n , a l t h o u g h i t may grade i n t o compact s k a r n w i t h i n a few f e e t . Under t h e m i c r o s c o p e , s e v e r a l f e a t u r e s of skarn become e v i d e n t w h i c h cannot be seen i n handspecimen, even i n c o a r s e - g r a i n e d v a r i e t i e s . Q u a r t z , p r e h n i t e , i l v a i t e , s p e c u l a r i t e and v e s u v i a n i t e a re f r e q u e n t l y found to be r e l a t i v e -l y abundant i n t h i n - s e c t i o n . C r o s s - c u t t i n g v e i n l e t s w h i c h e s t a b l i s h age r e l a t i o n s are a l s o more apparent and many r e p l a c e -ment f e a t u r e s a r e v i s i b l e o n l y under t h e m i c r o s c o p e . Garnet s k a r n , o f the compact v a r i e t y r e p l a c i n g v o l c a n i c r o c k s , i s f r e q u e n t l y almost c r y p t o c r y s t a l 1 i n e . Replacement by m a g n e t i t e i s t h e dominant p r o c e s s i n t h e f o r m a t i o n o f compact, f i n e - g r a i n e d ore i n which m a g n e t i t e i s d i s s e m i n a t e d throughout g a r n e t s k a r n . S k a r n formed i n l i m e s t o n e , however, i s c o a r s e - g r a i n e d and vuggy. M a g n e t i t e f i l l s s m a l l vugs and extends outward a l o n g c r y s t a l b o u n d a ries of l a r g e garnet c r y s t a l s ( P l a t e X X I I ) . Replacement t e x t u r e s are s u b o r d i n a t e i n r o c k o f t h i s t y p e and i t appears t h a t m a g n e t i t e , which i s everywhere l a t e r than s k a r n , f i r s t f i l l e d t hese open spaces and then began r e p l a c i n g garnet outward from them ( P l a t e X X I I I ) . Garnet and d i o p s i d e are the f i r s t s k a r n m i n e r a l s t o form and appear t o be contemporaneous. These m i n e r a l s are commonly d i s s e m i n a t e d i n each o t h e r and c r o s s - c u t t i n g v e i n s of g arnet and d i o p s i d e show c o n f l i c t i n g age r e l a t i o n s . D i o p -s i d e v e i n s i n g a r n e t , however, a r e more f r e q u e n t than garnet v e i n s i n d i o p s i d e . From t h i s i t can be i n f e r r e d t h a t i n some d e p o s i t s a t l e a s t f o r m a t i o n of d i o p s i d e o v e r l a p p e d and o u t -l a s t e d f o r m a t i o n of g a r n e t . E p i d o t e ( v a r i e t y p i s t a c i t e ) i s about as abundant as d i o p s i d e i n s k a r n . M a c r o s c o p i c a l l y e p i d o t e i s more prominent but much d i o p s i d e i s p r e s e n t as s m a l l g r a i n s d i s s e m i n a t e d through o t h e r w i s e compact g a r n e t . At l e a s t two s t a g e s of e p i d o t e m i n e r a l i z a t i o n can be r e c o g n i z e d i n most d e p o s i t s . The e a r l i e s t o f t h e s e s t a g e s i s found a l o n g j o i n t s or f a u l t s of s m a l l d i s p l a c e m e n t and as d i s s e m i n a t i o n s or i r r e g u l a r patches i n i n t r u s i v e g r a n i t i c r o c k s o r v o l c a n i c c o u n t r y r o c k s . E p i d o t i z a t i o n of t h i s type has long been r e c o g n i z e d i n t h e Coast Range and has g e n e r a l l y been i n t e r p r e t e d as an a l t e r -a t i o n p r o d u c t of p l a g i o c l a s e and ferromagnesium m i n e r a l s or as l a t e - s t a g e v e i n - f i l l i n g s ( e . g . Bacon, 195>7» p» 2 3 ) « These -lj .9-e p i d o t e v e i n s are f r e q u e n t l y c u t by garnet s k a r n and do not appear to be g e n e t i c a l l y r e l a t e d to c o n t a c t metasomatism ( P l a t e X I X ) . A l a t e r e p i d o t e , o f t e n found as v e i n s t r a n s e c t i n g c o n t a c t s o f garnet s k a r n and c o u n t r y r o c k , i s c o n s i d e r e d by the w r i t e r t o be an i n t e g r a l p a r t of s k a r n i f i c a t i o n even though such e p i d o t e i s u s u a l l y l a t e r t h a n t h e predominant g a r n e t -d i o p s i d e metasomatism. In t h o s e d e p o s i t s which show z o n i n g , e p i d o t e forms the outermost s k a r n zone and grades outward i n t o r e l a t i v e l y u n a l t e r e d c o u n t r y r o c k . E p i d o t e of one stage Is I d e n t i c a l t o t h a t o f the o t h e r . M a g n e t i t e i s everywhere l a t e r than s k a r n m i n e r a l s . I t o c c u r s as f r a c t u r e - f i l l i n g s , vug f i l l i n g s , or as a r e p l a c e -ment of s k a r n or c o u n t r y r o c k s . V e i n s and open-space f i l l i n g s of c a l c i t e , q u a r t z , and s u l p h i d e s are t h e l a s t o f t h e r e l a t i v e l y common sk a r n m i n e r a l s t o form, E u h e d r a l q u a r t z and c a l c i t e c r y s t a l s are f r e q u e n t l y found o c c u r r i n g t o g e t h e r i n vugs or v e i n s . T h e i r c o - e x i s t e n c e shows t h a t the r o c k s i n w h i c h t h e y were formed had c o o l e d t o at l e a s t l4.50°C ( B a r t h , 19!?1, p. 2 8 7 ) . M i n o r amounts of i l v a i t e , s p e c u l a r i t e , c h l o r i t e , and a c t i n o l i t e f r e q u e n t l y accompany q u a r t z and c a l c i t e . S e v e r a l o t h e r m i n e r a l s were found i n s k a r n but these -So-g e n e r a l l y o c c u r r e d too i n f r e q u e n t l y or In amounts too s m a l l t o ' e s t a b l i s h t h e i r age r e l a t i v e t o the main s k a r n m i n e r a l s . These i n c l u d e p r e h n i t e , wo 1 l a s t o n i t e , v e s u v i a n i t e , c h l o r i t e , t r e m o l i t e , and a c t i n o l i t e . A d e s c r i p t i o n of s k a r n - f o r m i n g m i n e r a l s e n c o u n t e r e d In t h i s s tudy f o l l o w s . They a r e g i v e n i n o r d e r of d e c r e a s i n g abundance. Garnet group Members o f th e g a r n e t group are by f a r the most abundant s k a r n m i n e r a l s . The c o m p o s i t i o n s of these g a r n e t s were c l o s e l y s t u d i e d because t h e y p r o v i d e an e x c e l l e n t guide to t h e g e n e r a l c o m p o s i t i o n of s k a r n . R e f r a c t i v e index and c e l l edge were used to determine c o m p o s i t i o n , u s i n g t h e v a l u e s p u b l i s h e d by S k i n n e r (1956). S p e c i f i c g r a v i t y d e t e r m i n a t i o n s were meanin g l e s s because o f the many i n c l u s i o n s i n t h e s e g a r n e t s . R e f r a c t i v e i n d i c e s were matched i n o i l i n w h i t e l i g h t and t h e i n d e x of the o i l was measured on a L e i t z M i c r o -R e f T a c t o m e t e r . D e t e r m i n a t i o n s on t h i s apparatus can be read d i r e c t l y t o 0.01 and e s t i m a t e d to t 0.002 u n i t s . R e s u l t s were r e p r o d u c i b l e w i t h i n t h e l i m i t s of r e a d i n g e r r o r . The -51-L e i t z R e f T a c t o m e t e r was c a l i b r a t e d a g a i n s t a n Abbe R e f r a c t -ometer and r e s u l t s checked w i t h i n 0 , 0 0 2 t o 0 , 0 0 7 u n i t s t o the upper l i m i t of t h e Abbe a p p a r a t u s (n = 1 . 7 0 ) , C e l l - e d g e d e t e r m i n a t i o n s were made by measuring i n t e r p l a n a r s p a c i n g s o f X - r a y powder p a t t e r n s and then c o r r e c t -i n g f o r f i l m s h r i n k a g e , A camera of 5 . 7 3 cm, dia m e t e r was used and 26 measurements were made w i t h an a c c u r a c y of i 0 , 0 5 ° , M a n g a n e s e - f i l t e r e d i r o n r a d i a t i o n was used t h r o u g h o u t . The l i m i t s of e r r o r i n r e f r a c t i v e i n d e x and c e l l edge d e t e r m i n a t i o n s t o g e t h e r r e s u l t i n a garnet c o m p o s i t i o n e r r o r of ± The c o m p o s i t i o n s of 60 garn e t s determined i n t h i s manner are shown i n F i g u r e 8 on a diagram m o d i f i e d from W i n c h e l l ( 1 9 5 8 ) , The d i r e c t i o n s of h y d r o g r a s s u l a r i t e ( F l i n t , McMurdie, and We 11 s , 191+1) and t h e f i c t i v e " h y d r o a n d r a d i t e " are a l s o shown i n r e l a t i o n t o the g r o s s u l a r i t e and a n d r a d i t e p a r a m e t e r s . F o r d (1915) found t h a t t w o - t h i r d s of a l l a n a l y z e d g a r n e t s c o u l d be r e p r e s e n t e d by t h r e e formulae? two f o r m u l a e are always predominant and t h e t h i r d averages about f i v e p e r -cent and i s not known t o exceed 20%. F i g u r e 8 shows t h a t g a r n e t s i n s k a r n d e p o s i t s c o n s i d e r e d i n t h i s s t u d y f a l l c l o s e to t h e g r o s s u l a r i t e - a n d r a d i t e j o i n w i t h s m a l l amounts of a l -mandite and/or s p e s s a r t i t e a p p e a r i n g i n most specimens. The preponderance o f g r a n d i t e g a r n e t (a s i m p l e d e s i g n a t i o n f o r - 5 2 -the g r o s s u l a r i t e - a n d r a d i t e s e r i e s ) i s i n a c c o r d w i t h t h e f i n d -i n gs of Wrigh t (1938) who showed t h a t garnet o f t h i s s e r i e s c o n s t i t u t e s more than 90% of the garnet i n c a l c a r e o u s c o n t a c t r o c k s . S e v e r a l d e t e r m i n a t i o n s p l o t beyond the p o i n t r e p r e -s e n t i n g pure a n d r a d i t e (see F i g . 8) and f o r t h e s e g a r n e t s , c e l l - e d g e measurements are a l l l e s s than or equal t o th a t of a n d r a d i t e . The r e f r a c t i v e i n d i c e s , however, of t h e s e g a r n e t s are too h i g h f o r t h e c o r r e s p o n d i n g c e l l edges. Garnets o f anoma l o u s l y hi g h r e f r a c t i v e i n d e x show no c o r r e l a t i o n w i t h the type of r o c k r e p l a c e d , c o l o u r o f garnet, or b i r e f r i n g e n c e . A h i g h TiC>2 c o n t e n t (5% T i O ^ or more) i s known t o occur i n garn e t s of h i g h r e f r i n g e n c e (Winchel 1, 1959,p.1-1-93). T h i r t e e n specimens, many o b t a i n e d from s i n g l e garnet c r y s t a l s , were a n a l y z e d s p e c t r o g r a p h i c a l l y f o r t i t a n i u m but averaged o n l y 0.02% T i . The re a s o n f o r the h i g h r e f r i n g e n c e remains unknown.. Garnets s t u d i e d i n t h i s p r o j e c t are v a r i o u s shades of r e d d i s h - b r o w n ; y e l l o w - g r e e n , green, d a r k brown and b l a c k v a r i e t i e s have a l s o been f o u n d . Garnets of two or even t h r e e d i s t i n c t c o l o u r s may o c c u r i n t h e same hand specimen. Where c o e x i s t i n g garnets of two c o l o u r s , such as red and gree n , were a n a l y z e d i n the manner d e s c r i b e d above, t h e d i f f e r e n c e i n composd t i on was l e s s than t h e a n a l y t i c a l e r r o r o f 5%. 1.90 1.88 1.86 1.84 1.82 1.80 1.78 1.76 1.74 1.72 Refractive index FIGURE 8 Composition of garnet in skarn as determined by cell edge and refractive index. Values for end members taken from Skinner (1956). Diagnostic components shown beside each sub-species. Complete c r y s t a l s are seldom found. S e v e r a l c r y s t a l f a c e s f r e q u e n t l y a r e found p r o j e c t i n g i n t o vugs or other c a v i t i e s but the remainder of such g r a i n s i s g e n e r a l l y m a s s i v e . Common c r y s t a l forms a r e t h e dodecahedran and t r a p e z o h d r a n or a c o m b i n a t i o n o f t h e s e . Faces a r e commonly s t r i a t e d . Many garnet c r y s t a l s show c o n c e n t r i c c o l o u r z o n i n g a c c e n t u a t e d by s t r i a t i o n s p a r a l l e l to t h e zones. Not a l l c r y s t a l s i n t h e same hand specimen show z o n i n g nor do a l l zoned c r y s t a l s show t h e same k i n d or degree of z o n i n g . Garnet has a v a r i e t y of t e x t u r e s t h a t depends t o some e x t e n t on the r o c k r e p l a c e d . Compact, f i n e - g r a i n e d garnet has v e r y commonly r e p l a c e d v o l c a n i c r o c k s , dykes, or p l u t o n i c r o c k s . Round or sub-round c l u s t e r s o f garnet g r a i n s a r e f r e q u e n t l y found e n c l o s e d i n massive m a g n e t i t e i n an aggregate r e s e m b l i n g g l o m e r o p o r p h y r i t i c t e x t u r e i n igneous r o c k s . Many garnet g r a i n s a r e m a r k e d l y b i r e f r i n g e n t :and f r e q u e n t l y such a n i s o t r o p i s m occurs i n c o n c e n t r i c s t r a i g h t -s i d e d zones, p a r a l l e l t o the c r y s t a l f a c e s , and a l t e r n a t i n g w i t h o t h e r w i s e s i m i l a r i s o t r o p i c zones ( P l a t e X X I ) . I n some specimens the a n i s o t r o p i c v a r i e t y forms i r r e g u l a r patches w i t h i n m a s s i v e , i s o t r o p i c , almost c r y p t o c r y s t a 1 1 i n e g a r n e t ; i n o t h e r specimens, b i r e f r i n g e n t garnet t r a n s e c t s the boundary between two c r y s t a l s . I n a few specimens, t h e a n i s o t r o p i c - 5 5 -type i s l i g h t e r i n c o l o u r t h a n t h e i s o t r o p i c v a r i e t y but o t h e r w i s e no c o r r e l a t i o n w i t h c o l o u r was noted; n e i t h e r i s t h e r e a tendency f o r b i r e f r i n g e n t g a r n e t s t o be found as a replacement of a p a r t i c u l a r r o c k type or t o be a p a r t i c u l a r c o m p o s i t i o n . I n c l u s i o n s of pyroxene, m a g n e t i t e , c a l c i t e , e p i d o t e , and o t h e r m i n e r a l s are seen i n most i s o t r o p i c g a r n e t s under t h e m i c r o s c o p e . B i r e f r i n g e n t g a r n e t s , however, a r e commonly more c o a r s e - g r a i n e d and f r e e o f i n c l u s i o n s t h a n i s o t r o p i c g a r n e t s . Many b i r e f r i n g e n t zones g i v e o f f - c e n t r e u n i a x i a l i n t e r f e r e n c e f i g u r e s ; some are o p t i c a l l y p o s i t i v e , o t h e r s are n e g a t i v e . A few g r a i n s shew what appear to be o f f - c e n t r e b i a x i a l i n t e r f e r e n c e f i g u r e s but a t t e m p t s t o c o n f i r m t h i s w i t h the u n i v e r s a l s t a g e were u n s a t i s f a c t o r y . B i a x i a l a n d r a d i t e has been r e p o r t e d by Stose and G l a s s (1938) and b i a x i a l g r o s s u l a r i t e by T a y l o r ( 1 9 3 5 ) . Many i n v e s t i g a t o r s have n o t e d the anomalous b i r e -f r i n g e n c e d i s p l a y e d by garnets i n c o n t a c t d e p o s i t s but few w r i t e r s have o f f e r e d t o e x p l a i n t h i s phenomenon. Yoder (1950) suggested the a n i s o t r o p i s m i s caused by a change i n the c r y s t a l s t r u c t u r e brought about by s u b s t i t u t i o n of f e r r i c i r o n f o r t r i v a l e n t aluminum. Yoder c o n s i d e r e d t h i s t o r e s u l t i n a sub-group of symmetry lower than t h a t o f the b a s i c g r o s s u l a r i t e - 5 6 -s t r u c t u r e . I t i s d i f f i c u l t t o understand how such s u b s t i t u t i o n would cause b i r e f r i n g e n c e , as f e r r i c i r o n and aluminium a r e the main m e t a l l i c elements i n a n d r a d i t e and g r o s s u l a r i t e , r e s p e c t i v e l y . As a con t i n u o u s s o l i d s o l u t i o n s e r i e s e x i s t s between th e s e two end members anomalous p r o p e r t i e s s u c h as b i r e f r i n g e n c e would not be expe c t e d . B i r e f r i n g e n c e i n a n o r m a l l y i s o t r o p i c m a t e r i a l i s evi d e n c e of a l o w e r i n g o f i t s o p t i c a l symmetry. To deter m i n e whether t h e r e was a c o r r e s p o n d i n g d e c r e a s e i n t h e c r y s t a l symmetry of b i r e f r i n g e n t g a r n e t , X-ray powder d i f f r a c t i o n photographs of s e v e r a l d o u b l y r e f r a c t i n g g a r n e t s were t a k e n and compared w i t h i s o t r o p i c garnets of comparable c o m p o s i t i o n . In every i n s t a n c e , t h e p a t t e r n s were i d e n t i c a l w i t h i n the l i m i t s of r e a d i n g e r r o r . An example o f such a p a i r i s shown i n T a b l e 7 . Other m i n e r a l s which show anomalously low o p t i c symmetry are b i a x i a l q u a r t z and c a l c i t e . N e i t h e r of t h e s e m i n e r a l s have been shown t o be c r y s t a 1 l o g r a p h i c a l l y d i f f e r e n t from t h e normal u n i a x i a l v a r i e t y . F r o n d e l (1962,p.133) found t h a t i n q u a r t z "a b i a x i a l c h a r a c t e r can be produced a r t i f i c a l l y by c o m p r e s s i o n i n d i r e c t i o n s i n c l i n e d to t h e o p t i c a x i s , as w e l l as by a t h e r m a l g r a d i e n t , or by a p p l i c a t i o n of an e l e c t r i c f i e l d " . B i a x i a l c a l c i t e , f r e q u e n t l y showing bent t w i n n i n g -57-l a m e l l a e , has been noted by many i n v e s t i g a t o r s . P a u l i t s c h (1901) reviewed d a t a on the b i a x i a l n ature o f c a l c i t e and conclud e d t h a t the phenomenon had not been s a t i s f a c t o r i l y e x p l a i n e d . I f t h e r e a s o n f o r t h e subnormal o p t i c a l symmetry d i s p l a y e d by these m i n e r a l s c o u l d be e x p l a i n e d i t might e x p l a a l s o b i r e f r i n g e n t g r a n d i t e g a r n e t s . T a b l e 7 Comparison of i n t e r p l a n a r s p a c i n g s f o r b i r e f r i n g e n t and  i s o t r o p i c g a r n e t s of c o m p o s i t i o n An^5 Gr ^ yA1_Qg U.B.C. 3761 - I s o t r o p i c U.B.C. 3671 - A n i s o t r o p i c d (meas.) d (meas.) 11. 12. 13 . U+. 15. 16. 17. 9 . 10. 3 . k. 5 . 6 . 7 . 8 . 1. 2 . 2 . 9 8 2 . 6 6 2 . 5 3 2.1+3 2.3k 2.17 1.931+ 1.753 1.719 r . 6 5 2 1.593 1.1+88 1.299 1 .270 1.109 1.090 1.056 2 . 9 8 2 . 6 7 2 . 5 5 2.1+1+ 2. 31+ 2 . 18 1.937 1.757 1.723 1.656 1.597 1.I192 1.299 1.270 1 .109 1.090 1.056 - 5 8 -F r o n d e l (1962) noted t h a t a ther m a l g r a d i e n t produced b i a x i a l q u a r t z . Wright (191.5) d i s c o v e r e d t h a t garnet l o s t i t s b i r e f r i n g e n c e a f t e r b e i n g heated f o r a few hours at 800°C and d i d not r e g a i n i t a f t e r s e v e r a l hours at 600°C. A s i m i l a r experiment was performed on a n d r a d i t e by S t o s e and G l a s s ( 1 9 3 8 ) and t h e y found i t became i s o t r o p i c a t 860°C. and d i d not i n v e r t t o i t s o r i g i n a l a n i s o t r o p i s m on c o o l i n g . Specimens of a n d r a d i t e from the Pewabic mine, N.M. l o s t t h e i r b i r e f r i n g e n c e at 860°C. ( A l l e n and Fahey, 19^7»p• 89U-) • G r o s s u l a r i t e has been shown to l o s e i t s b i r e f r i n g e n c e at temperatures between 700°~800°C. (Stone, 1 9 5 9 )• These workers proposed t h a t b i r e f r i n g e n t garnet c o u l d be used as a rough g e o l o g i c thermometer, based on t h e e x p e r i m e n t a l evidence c i t e d above. They c o n c l u d e d that b i r e -f r i n g e n t garnet has formed below, and i s o t r o p i c g a r n e t above, a temperature of about 750°-850°C. S l i g h t v a r i a t i o n s i n c o m p o s i t i o n of g a r n e t c o u l d p o s s i b l y produce anomalous o p t i c a l p r o p e r t i e s . In a s t u d y of mixed c r y s t a l s o f s i m p l e s a l t s , Bunn ( 1 9 3 3 ,P« 5 6 9) found t h a t c u b i c c r y s t a l s o f le a d n i t r a t e and barium n i t r a t e became b i r e f r i n g e n t and p l e o c h r o i c when c o l o u r e d w i t h methylene b l u e . The c o n t a m i n a t e d n i t r a t e c r y s t a l s , when f i r s t formed, were a s i n g l e s o l i d phase. O p t i c a l l y , each cube was d i v i d e d d i a g o n a l l y i n t o s i x pyramids w i t h t h e i r a p i c e s at the c e n t r e of t h e - 5 9 -c r y s t a l s . The pyramids opened out to s i x cube f a c e s , each pyramid h a v i n g the same o p t i c a l o r i e n t a t i o n w i t h r e s p e c t t o I t s own cube f a c e . These p y r a m i d a l forms are s i m i l a r to t h o s e found i n b i r e f r i n g e n t g a r n e t s showing b i a x i a l i n t e r f e r e n c e f i g u r e s w i t h o p t i c a n g l e s of 5 0 - 9 0 ° (Winche 11, 1 9 5 9 ,p. 1+90) . I n another set o f e x p e r i m e n t s , Bunn (p.571) found t h a t s o l u t i o n s of ammonium c h l o r i d e c o n t a i n i n g the d i v a l e n t c h l o r i d e s of Mn, Fe, Co, N i , or Cu c r y s t a l l i z e d i n t o b i r e f r i n g e n t c u b i c c r y s t a l s . These cubes were d i v i d e d , d i a g o n a l l y i n t o s i x s e c t o r s , each o f whi c h was u n i a x i a l w i t h i t s o p t i c a x i s normal t o the cube f a c e . When a l l o w e d t o r e s t f o r t h r e e y e a r s i n the dry s t a t e , the contami n a t e d ammonium c h l o r i d e c r y s t a l s , w h i c h were o r i g i n a l l y p h y s i c a l l y homogeneous, s e p a r a t e d i n t o two s o l i d phases. S m a l l b i r e f r i n g e n t c r y s t a l s appeared on t h e s u r f a c e and the b i r e f r i n g e n c e of the main ammonium c h l o r i d e c r y s t a l s had decreased p r a c t i c a l l y t o z e r o . The r a t e o f t h i s " e x s o l u t i o n " i s a p p a r e n t l y not t h e same f o r a l l m e t a l l i c c h l o r i d e s ; t e t r a -gonal c r y s t a l s o f ammonium c u p r i c c h l o r i d e " e x s o l v e d " w i t h i n t h r e e months, the o t h e r c h l o r i d e s t o o k l o n g e r t o s e p a r a t e (Bunn, 1933,P .57U-) • Bunn c o n c l u d e d t h a t , i n t h e examples s t u d i e d , t h e o p t i c a l e f f e c t s showing t h e p r e s e n c e of i m p u r i t i e s are s t r o n g e r when t h e c r y s t a l s have grown r a p i d l y than when they grew s l o w l y . Slow-growing c r y s t a l s a re a p p a r e n t l y a b l e t o r e j e c t i m p u r i t i e s a r r i v i n g a t t h e i r faces whereas, when -60-growing r a p i d l y , t h e y a r e u n a b l e to- do t h i s c o m p l e t e l y . In t i m e , however, even the r a p i d l y - c r y s t a l l i z e d c r y s t a l s were a b l e t o r e j e c t t h e i r i m p u r i t i e s as a second s o l i d phase (Bunn , 1 9 3 3 » p.5 7 2 ) . The e f f e c t s produced by i m p u r i t i e s i n t h e s e c h e m i c a l l y and c r y s t a 1 l o g r a p h i c a 1 l y s i m p l e s a l t s a r e s t r i k i n g l y s i m i l a r t o t h o s e o b s e r v e d i n b i r e f r i n g e n t g a r n e t . M e n t i o n has been made elsewhere t h a t b i r e f r i n g e n t garnets are more common as replacements o f l i m e s t o n e . Such g a r n e t s c o u l d c o n c e i v a b l y have formed by r a p i d p r e c i p i t a t i o n from s o l u t i o n s brought i n t o c o n t a c t w i t h t h e h i g h l y r e a c t i v e c a r b o n a t e . Rapid growth of c r y s t a l s would a l s o be enhanced by h i g h t e m p e r a t u r e s . These r a p i d l y - g r o w n c r y s t a l s would not be a b l e to r e j e c t i m p u r i t i e s i n c o r p o r a t e d i n t o t h e i r s t r u c t u r e and would t h e r e f o r e be b i r e f r i n g e n t . These i m p u r i t i e s would be r e t a i n e d i n the c r y s t a l and would n ot s e p a r a t e i n t o a second phase. I t has been p r e v i o u s l y noted t h a t b i r e f r i n g e n t g a r n e t s a r e g e n e r a l l y f r e e of s o l i d i n c l u s i o n s . I s o t r o p i c g a r n e t , on t h e o t h e r hand, i s more common i n v o l c a n i c r o c k s and i s g e n e r a l l y crowded w i t h minute i n c l u s i o n s of a v a r i e t y o f m i n e r a l s . Such garnet c o u l d have formed s l o w l y as a r e s u l t of s o l u t i o n s brought i n t o c o n t a c t w i t h t h e s e c h e m i c a l l y l e s s - r e a c t i v e v o l c a n i c r o c k s . Lower temperature c o u l d a l s o s l o w the growth -61-of g a r n e t of t h i s t y p e . These more s l o w l y - g r o w i n g g r a i n s would r e j e c t i m p u r i t i e s now seen as s o l i d i n c l u s i o n s i n i s o t r o p i c g a r n e t . T h i s p r o p o s a l t h a t b i r e f r i n g e n t g a r n e t formed, at a h i g h e r temperature and more q u i c k l y than i s o t r o p i c garnet c o n t r a s t s w i t h the c o n c l u s i o n s of W r i g h t , Stose and G l a s s , Stone, and T a y l o r r e a c h e d from t h e i r e xperiments on h e a t i n g b i r e f r i n g e n t g a r n e t . The d i f f e r e n c e can perhaps be e x p l a i n e d i n t h i s way: when b i r e f r i n g e n t g a r n e t i s s u b i e c t e d t o p r o l o n g e d h e a t i n g , the i m p u r i t i e s p r e s e n t i n t h e c r y s t a l have time to a r r a n g e themselves i n t o d i s c r e t e g r a i n s . These are r e j e c t e d by the garnet which then becomes i s o t r o p i c . Because of the more complex c h e m i s t r y and c r y s t a l l o g r a p h y of g a r n e t , p r o l o n g e d h e a t i n g i s r e q u i r e d t o produce i n t h i s m i n e r a l what time a l o n e produced i n the s i m p l e s a l t s s t u d i e d by Bunn. The i n c l u s i o n s , once t h e y have been r e j e c t e d by t h e garnet s t r u c t u r e , would not be r e - i n c o r p o r a t e d at lower temperatures and t h e r e f o r e garnet would not r e g a i n i t s b i r e -f r i n g e n c e upon c o o l i n g . A l t e r n a t e i s o t r o p i c and a n i s o t r o p i c zones, or i r r e g u l a r b i r e f r i n g e n t " p a t c h e s " i n g r a n d i t e , i f the p r o c e s s o u t l i n e d above even approximates what a c t u a l l y t a k e s p l a c e i n n a t u r e , c o u l d t h e r e f o r e be caused by d i f f e r e n t r a t e s of c r y s t a l growth i n g a r n e t . D e p c s i t i o n a l r a t e s can change w i t h t i m e , t e m p e r a t u r e , c o m p o s i t i o n o f t h e d e p o s i t i n g s o l u t i o n s , c o m p o s i t i o n of t h e h o s t r o c k s , or o t h e r f a c t o r s . -62-I t i s c o n c l u d e d t h a t because temperature i s o n l y one f a c t o r which can cause b i r e f r i n g e n c e i n i s o t r o p i c compounds, a n i s o -t r o p i s m i n g a r n e t s cannot be c o r r e l a t e d w i t h temperature o f format i on. Pyroxene Green, a n h e d r a l pyroxene i s next i n abundance t o g a r n e t . Pyroxene oc c u r s as v e i n s , i r r e g u l a r p a t c h e s , or f i n e -g r a i n e d m i c r o s c o p i c d i s s e m i n a t i o n s i n garnet s k a r n . L o c a l l y , i t can form a major p r o p o r t i o n of s k a r n but g e n e r a l l y i t i s s u b o r d i n a t e t o g a r n e t . The most common form i s medium-grained, a n h e d r a l , g r a n u l a r a g g r e gates o r v e i n s of green c r y s t a l s i n garnet or a l t e r e d v o l c a n i c r e c k s . In l i m e s t o n e , however, e u h e d r a l c r y s t a l s up to f i v e i nches long and one i n c h t h i c k have been found. C r y s t a l s from the P r e s c o t t mine, Texada I s l a n d , a r e "perched" on a stem of pyroxene a t t a c h e d t o a l a y e r o f m a g n e t i t e ( P l a t e X ) . The i n t e r m e d i a t e r e f r a c t i v e index (ny) of f i v e specimens ranged from I .689 to 1.695 t 0.002. O p t i c a n g l e measurements showed 2V = 55 t 2°. These p r o p e r t i e s c l a s s i f y the m i n e r a l as s a l i t e , an i n t e r m e d i a t e member o f the d i o p s i d e --63-h e d e n b e r g i t e s e r i e s (Hess , I9I4.I; Winche 11,1959, F i g ,289,p.l|l 0) . A c c o r d i n g t o c o r r e l a t i o n c h a r t s p u b l i s h e d by Kennedy ( 191-1-7, p.565) these r e f r a c t i v e i n d i c e s c o r r e s p o n d to c o m p o s i t i o n s r a n g i n g from Diyj^He2^ t o D i ^ H e ^ c j . Long, brown pyroxene c r y s t a l s w i t h a d u l l b r o n z e -l i k e l u s t r e c o e x i s t w i t h garnet and i l v a i t e i n s k a r n at I r o n H i l l . R e f r a c t i v e i n d e x measurements show: n x = 1.721, ny = 1.729, n z = 1.714-7. These c o r r e s p o n d to pyroxene of c o m p o s i t i o n Hes^Di (Kennedy, I9I4.7,p.565) and. c l a s s i f y the m i n e r a l as h e d e n b e r g i t e (Hes s, I9I4-I) • E p i d o t e group E p i d o t e i s u b i q u i t o u s i n skarns o f so u t h w e s t e r n B r i t i s h C o l u m b i a , I t i s the l a s t o f t h e major c a l c - s i 1 i c a t e m i n e r a l s t o form and, i n zoned d e p o s i t s , predominates i n the outermost zone. The most common v a r i e t y i s green p i s t a c i t e o c c u r r i n g i n v e i n s , p a t c h e s , d i s s e m i n a t i o n s , or aggregates of eu h e d r a l t o s u b h e d r a l c r y s t a l s . In t h i n s e c t i o n , the m i n e r a l i s p l e o c h r o i c from c o l o u r l e s s t o s t r a w y e l l o w and has i n c l i n e d e x t i n c t i o n . The i n t e r m e d i a t e r e f r a c t i v e i n d e x (ny) of t h r e e specimens was measured and gave t h e f o l l o w i n g : n y = 1 .750, -61+-1 .758, and 1.775* These c o r r e s p o n d t o c o m p o s i t i o n s o f 2 7 , 3 3 , and 1+7 m o l e c u l a r p e r c e n t of Ca2Fe^ (GH)S i ^ O ^ * r e s p e c t i v e l y ( W i n c h e l l , 1959,Fig.3l;3,P.1+1+9) . A s m a l l amount of c l i n o z o i s i t e ( C a 2 A l ^ (OH^i-^O^) was i d e n t i f i e d i n a few samples and i s found on the o u t s i d e border of the e p i d o t e zone (Zone 3 j sub-zone 1 ( b ) ; T a b l e 1 1 ) . C a l c i t e C a l c i t e i s most common i n s k a r n formed as a r e p l a c e -ment o f l i m e s t o n e . In t h i s type of s k a r n i t f i l l s vugs or s m a l l openings between e u h e d r a l g a r n e t c r y s t a l s ( P l a t e XX) and c l e a v a g e rhombs i n t h e s e openings a r e f r e q u e n t l y t h r e e to f o u r i n c h e s w i d e. A l a r g e vug i n s k a r n at the I r o n H i l l mine c o n t a i n e d i n w a r d - p r o j e c t i n g c r y s t a l s o f t r a n s l u s c e n t I c e l a n d s p a r , some of which showed c o n c e n t r i c zones of a r e d d u s t -l i k e m a t e r i a l b e l i e v e d t o be h e m a t i t e . Rhombs of t r a n s p a r e n t c a l c i t e have been r e p o r t e d a l s o from the Merry Widow mine. C a l c i t e , accompanied by s u l p h i d e s , q u a r t z , or o t h e r m i n e r a l s , c u t s g a r n e t , d i o p s i d e , and e p i d o t e and i s one of the f i r s t o f the n o n - c a l c i u m - s i l i c a t e m i n e r a l s to form i n s k a r n . D i s s e m i n a t e d c a l c i t e i n c l u s i o n s common i n garnet and d i o p s i d e p r o b a b l y were i n c o r p o r a t e d by these c r y s t a l s d u r i n g growth. - 6 5 -Q u a r t z Q u a r t z i s found i n s m a l l q u a n t i t i e s i n s k a r n and i s everywhere a l a t e - f o r m i n g m i n e r a l . P r i s m a t i c c r y s t a l s w i t h p y r a m i d a l t e r m i n a t i o n s o c c u r w i t h c a l c i t e i n v e i n s or vugs. Many examples of such c o e x i s t i n g c a l c i t e and q u a r t z were examined i n t h i s s e c t i o n and. nowhere was t h e r e evidence of r e a c t i o n . In s e v e r a l specimens, q u a r t z c r y s t a l s which p r o j e c t t h r o u g h sealenohedrons o f c a l c i t e i n t o open vugs have s h a r p , u n c o r roded c o n t a c t s w i t h c a l c i t e . Amphibole group C l u s t e r s of a c i c u l a r green a c t i n o l i t e c r y s t a l s are f r e q u e n t l y found w i t h e p i d o t e on the margins of s k a r n zones. Bodies of garnet s k a r n a r e , i n p l a c e s , rimmed, by a t h i n d i s -c o n t i n u o u s zone o f a c t i n o l i t e . Much i n t e r s t i t i a l a c t i n o l i t e d i s s e m i n a t e d w i t h c h l o r i t e In d i o p s i d e may be an a l t e r a t i o n p r o d u c t . O p t i c a l p r o p e r t i e s o f one specimen of a c t i n o l i t e a r e : N x = 1 . 6 5 5 , N y = 1 . 6 6 2 , N z = 1 . 6 8 0 ; (-)2V = 8 3 + 2 ° . These parameters are a l s o s i m i l a r t o those f o r i n t e r m e d i a t e members o f t h e cummingtonite s e r i e s but X-ray powder d i f -f r a c t i o n p a t t e r n s showed the m i n e r a l to be o f the t r e m o l i t e -f e r r o t r e m o l i t e s e r i e s . The o p t i c a l p r o p e r t i e s d e s c r i b e d above p l a c e t h i s m i n e r a l almost e x a c t l y midway i n c o m p o s i t i o n -66-between the two end members; t h a t i s , the c o m p o s i t i o n o f t h i s a c t i n o l i t e i s C a 2 M g 2 . 5 F e 2 . 5 S i 8 0 2 2 ( ° H ) 2 (Winche 1 1 , 1 9 5 9 ,Fig. 3 2 3 , P.l+33). An amphibole a p p r o a c h i n g t h e c o m p o s i t i o n of g r u n e r i t e was i d e n t i f i e d from Texada I s l a n d by Swanson (192I4.,p. 1 2 0 A ) on the b a s i c o f r e f r a c t i v e i n d e x d e t e r m i n a t i o n . However, no members of the cummingtonite ( k u p f f e r i t e - g r u n e r i t e ) s e r i e s were found by the p r e s e n t w r i t e r . P r e h n i t e Narrow v e i n s o f p r e h n i t e , some showing p o o r l y -developed " b o w - t i e " s t r u c t u r e , t r a n s e c t most p r i m a r y s k a r n m i n e r a l s . I t i s not known f o r c e r t a i n whether such p r e h n i t e i s a l a t e - f o r m i n g p r i m a r y skarn m i n e r a l or whether i t i s an a l t e r a t i o n of p r e - e x i s t i n g m i n e r a l s . V e s u v i a n i t e A n h e d r a l t o s u b h e d r a l v e s u v i a n i t e was i d e n t i f i e d i n specimens from t h e I r o n H i l l mine. Most g r a i n s occur as d i s s e m i n a t i o n s i n g a r n e t - p y r o x e n e s k a r n but s e v e r a l i n t e r -s t i c e s between e u h e d r a l g a r n e t c r y s t a l s a r e c o m p l e t e l y f i l l e d w i t h v e s u v i a n i t e . -67-W o l l a s t o n i t e T h i s i s one of t h e l e s s common m i n e r a l s found i n skarns c o n s i d e r e d i n t h i s s t u d y . I t i s found w i t h garnet and c a l c i t e i n the P r e s c o t t mine, Texada I s l a n d . I l v a i t e T h i s m i n e r a l was found o n l y a t t h e I r o n H i l l mine. At t h i s l o c a l i t y , l o n g b l a c k i l v a i t e c r y s t a l s o c c u r w i t h garnet and h e d e n b e r g i t e i n s k a r n . Q u a r t z c r y s t a l s , p r o j e c t i n g through c a l c i t e i n t o a h o l l o w vug, a r e covered w i t h a d r u s y c o a t i n g of i l v a i t e and m a g n e t i t e . Q u a r t z - c a l c i t e v e i n s i n t h i s mine a l s o c a r r y minor amounts of i l v a i t e . A x i n i t e L i g h t p u r p l e c r y s t a l s o f a x i n i t e are f o u n d i n a q u a r t z - c a 1 c i t e v e i n i n the Brynnor Mines L t d . open p i t . The v e i n appears t o f o l l o w a c o n t a c t between a n d e s i t e and s k a r n . M e t a l l i c m i n e r a l s meta11ic M a g n e t i t e , p y r i t e , and c h a l c o p y r i t e a r e the main m i n e r a l s i n the m a g n e t i t e d e p o s i t s c o n s i d e r e d i n -68-t h i s s t u d y . In most mines, t h e p r o p o r t i o n o f s u l p h i d e s t o o x i d e s i s v e r y low. M a g n e t i t e i s , o f c o u r s e , the main oxide m i n e r a l and s u l p h i d e s o c c u r as d i s s e m i n a t i o n s i n m a g n e t i t e or as i r r e g u l a r masses. The age r e l a t i o n between m a g n e t i t e and s u l p h i d e s i s not c o n s i s t e n t even w i t h i n a s i n g l e d e p o s i t ; t h e r e i s e v i d e n c e of s u l p h i d e s f o r m i n g contemporaneously w i t h or l a t e r t h a n m a g n e t i t e but none wh i c h would i n d i c a t e t h a t t h e y formed b e f o r e m a g n e t i t e . P y r i t e and c h a l c o p y r i t e a r e the most abundant s u l p h i d e s ; p y r r h o t i t e , s p h a l e r i t e , a r s e n o p y r i t e , and c o b a l t i t e o c c u r i n minor amounts. Magnet i t e G r a n u l a r , s u b h e d r a l , medium-to c o a r s e - g r a i n e d , b l u e -b l a c k m a g n e t i t e i s t h e most common h a b i t o f t h i s m i n e r a l . C o a r s e - g r a i n e d vuggy m a g n e t i t e o c c u r s i n l i m e s t o n e and a f i n e - orrmedium-grained v a r i e t y r e p l a c e s v o l c a n i c r o c k s . M a g n e t i t e i s s k a r n , p a r t i c u l a r l y i n garnet s k a r n , appears t o have f i r s t f i l l e d c a v i t i e s and then proceeded a l o n g garnet c r y s t a l b o u n d a ries and t h e n i n t o t h e c r y s t a l s t h e m s e l v e s . C r y s t a l boundary replacement has r e s u l t e d i n rounded garnet c r y s t a l s i n a m a t r i x of m a g n e t i t e ( P l a t e X X I I I ) . Complete replacement o f garnet t h e n f o l l o w e d and s e v e r a l examples of m a g n e t i t e a p p a r e n t l y pseudomorphous a f t e r garnet were seen. - 6 9 -F r a c t u r e - f i 1 1 i n g f o l l o w e d by replacement i s the dominant p r o c e s s o f d e p o s i t i o n i n v o l c a n i c r o c k s ( P l a t e X I I ) ; complete replacement a l o n g an a d v a n c i n g c h e m i c a l " f r o n t " r e s u l t i n g i n bulbous forms and s h a r p c o n t a c t s o f ma g n e t i t e d e p o s i t s predominates i n l i m e s t o n e ( P l a t e X I ) . Under t h e mi c r o s c o p e the m a g n e t i t e u s u a l l y forms a g r a n u l a r aggregate of i n t e r l o c k i n g , i s o t r o p i c a n h e d r a l g r a i n s . M a g n e t i t e pseudomorphous a f t e r garnet and s p e c u l a r i t e was noted a l t h o u g h i t i s not common. Some samples show an i n t e r -l o c k i n g aggregate o f m a g n e t i t e g r a i n s which a re d i s t i n c t l y a n i s o t r o p i c but n o n - p l e o c h r o i c . A n i s o t r o p i s m v a r i e s i n i n t e n s i t y from a r e a t o area i n a s i n g l e s e c t i o n but the p o l a r i z a t i o n c o l o u r s a r e the same: b l u e - g r a y to r e d d i s h -brown. A t e x t u r e resembling p o l y s y n t h e t i c t w i n n i n g i s seen i n some m a g n e t i t e of t h i s t y p e . A n i s o t r o p i c m a g n e t i t e has been r e p o r t e d from t h e c o n t a c t metasomatic d e p o s i t at C o r n w a l l , Pa. (Hickock, 1 9 3 3) but t h e reason f o r the anomalous o p t i c a l p r o p e r t y i s u n s t a t e d . An X-ray powder d i f f r a c t i o n p a t t e r n of a n i s o t r o p i c m a g n e t i t e from the I r o n H i l l mine, Vancouver I s l a n d , showed t h a t such m a g n e t i t e had normal c u b i c symmetry. M a g n e t i t e w i t h rhombohedral symmetry at -158°C. has been r e p o r t e d by Rooksby and W i l l i s ( 1 9 5 3 ) . However, Abrahams and Calhoun (1953) b e l i e v e t h e t r a n s i t i o n i s t o o r t h o r h o m b i c symmetry. To determine whether o r not a n i s o t r o p i c m a g n e t i t e -70-c o n t a i n s e x c e s s i v e t i t a n i u m a specimen from the Y e l l o w K i d d e p o s i t was a n a l y z e d . I t c o n t a i n e d o n l y 0.027% T i , about average f o r i s o t r o p i c m a g n e t i t e from t h e same d e p o s i t . C o n t a c t metasomatic m a g n e t i t e i s c h a r a c t e r i s t i c a l l y low i n common t r a c e element i m p u r i t i e s found i n the m a g n e t i t e of o t h e r types o f d e p o s i t s . Elements such as t i t a n i u m and phosphorous, r e l a t i v e l y abundant i n many magmatic m a g n e t i t e d e p o s i t s , a r e found i n n e g l i g i b l e q u a n t i t i e s i n c o n t a c t d e p o s i t . Manganese i s common i n many s e d i m e n t a r y i r o n ores but i s a v e r y minor c o n s t i t u e n t of c o n t a c t m a g n e t i t e d e p o s i t s . A n a l y s e s f o r P, T i , Mn, and o t h e r elements i n c o n c e n t r a t e s from s e v e r a l B r i t i s h Columbia d e p o s i t s are g i v e n i n T a b l e 8 , u s i n g data from company f i l e s and from E l v e r ( 1 9 6 3 ) : T a b l e 8 P a r t i a l a n a l y s e s of m a g n e t i t e c o n c e n t r a t e s , B r i t i s h Columbia ( A n a l y s t , W.F. White, G e o l o g i c a l Survey, Canada) Mine P Mn T i Elements Cr {%) As Brynnor• 0 . 0 5 _ _ 0 . 0 3 J edway 0 . 0 2 0.17 Nimpkish 0 . 0 1 3 0.16 — Texada 0.011 0.13 0.09 0.0011; 0.007 Zeba11os 0 . 0 2 0.1 0 . 0 8 0 . 0 0 0 8 not d e t e c ' d ( o t h e r elements f o r Z e b a l l o s - Z r O.OI4., Sn 0.000£, NI 0.-002, Co 0 . 0 0 1 , V 0 . 0 0 3 ) -71-, Masses of m a g n e t i t e w i t h c o l l o f o r m t e x t u r e have been found i n the K i n g f i s h e r , Merry Widow, S h a m r o c k - B l a c k j a c k , Y e l l o w K i d , and Bacon Lake d e p o s i t s . These masses range from a f r a c t i o n of an i n c h t o one f o o t i n diameter and are r o u g h l y h e m i s p h e r o i d a l i n shape ( P l a t e X V I ) . Sect i o n s • t h r o u g h l a r g e r h e m i s p h e r o i d s or " n o d u l e s " show a r a d i a t i n g s t r u c t u r e and c o n c e n t r i c banding. In s m a l l e r n o d u l e s the r a d i a t i n g s t r u c t u r e i s l a c k i n g . The banding i s caused by l a y e r s of m a g n e t i t e of d i f f e r i n g g r a i n s i z e . Some l a y e r s are composed of a c i c u l a r m a g n e t i t e c r y s t a l s up to -jr i n c h l o n g ; i n o t h e r s , the m a g n e t i t e i s e x t r e m e l y f i n e - g r a i n e d and e x h i b i t s an i r r e g u l a r f r a c t u r e p a t t e r n or " c r a c k l e d " t e x t u r e . The d i f f e r e n t l a y e r s f r e q u e n t -l y s p a l l o f f when s t r u c k and some are s e p a r a t e d by t h i n p a r a l l e l l a y e r s of c a l c i t e . The r a d i a t i n g s t r u c t u r e i s pro-duced i n two ways: (1) p a r a l l e l e l o n g a t e m a g n e t i t e c r y s t a l s a r r a n g e d p e r p e n d i c u l a r to the banding (2) t h i n , r a d i a l , b i -f u r c a t i n g c r a c k s e x t e n d i n g inward from the o u t e r s u r f a c e of each h e m i s p h e r o i d . Some c r a c k s o n l y p e n e t r a t e about one q u a r t e r of the way i n t o t h e mass, othe r s extend t o t h e c e n t r e . Some cr a c k s a re f i l l e d by c a l c i t e . The o u t e r s u r f a c e s o f the hem i s p h e r o i d s a re p a r a l l e l t o the cur v e d i n n e r bands. T e x t u r e s such as ban d i n g , b i f u r c a t i n g r a d i a l c r a c k s , and " c r a c k l e d " appearance, t o g e t h e r w i t h a s p h e r o i d a l , shape, have been a t t r i b u t e d by B a s t i n (19^0) to d e p o s i t i o n from a - 7 2 -c o l l o i d a l d i s p e r s i o n . A c o l l o i d a l d i s p e r s i o n i s a system i n which e x t r e m e l y f i n e - g r a i n e d p a r t i c l e s are suspended, more or l e s s i n d e f i n i t e l y , i n a f l u i d medium. P a r t i c l e s i z e i n the c o l l o i d a l range i s about 5 rou to 200 mu (Hartman, 1914-7) • The f o l l o w i n g p o i n t s a r e c h a r a c t e r i s t i c of c o l l o i d a l d i s p e r s i o n s : (1) extreme buoyancy (2) p a r t i c l e s a r e a f f e c t e d by Brownian movement (3) the p a r t i c l e s are e a s i l y absorbed (U.) some s u b s t a n c e s , when i n t h e c o l l o i d a l s t a t e , c a r r y an e l e c t r i c a l charge w h i c h r e p e l s the p a r t i c l e s and s t a b i l i z e s the d i s p e r s i o n . F l o c c u l a t i o n i s brought about by n e u t r a l i z i n g t h i s charge (5) the l a r g e s u r f a c e a rea exposed i s f a v o u r a b l e to c h e m i c a l i n t e r a c t i o n between the s o l i d and the e n c l o s i n g f l u i d s and (6) th e d i s p e r s i o n has l i t t l e e f f e c t on the p h y s i c a l p r o p e r t i e s of t h e s o l u t i o n ( t h i s i s p a r t i c u l a r l y t r u e of l y o p h o b i c c o l l o i d s such as a s u s p e n s i o n of a non-hydrous m e t a l l i c s u b s t a n c e i n a hydrous medium). C o l l o f o r m t e x t u r e i s common i n many m i n e r a l s and th e s e a r e c o n s i d e r e d t o have been d e p o s i t e d from c o l l o i d a l d i s p e r s i o n ( Bast i n , 1950; Boyde 11, 192U-25; L i n d g r e n , I92I4). E v i d e n c e o f c o l l o i d a l d e p o s i t i o n , however, m e r e l y i n d i c a t e s t h a t the m i n e r a l was once i n t h e c o l l o i d a l s t a t e and need not have been c a r r i e d t o i t s p r e s e n t p o s i t i o n as a c o l l o i d . A l s o , a l l substances p r e c i p i t a t i n g from e l e c t r o l y t i c s o l u t i o n s must -73-pass through t h e c o l l o i d a l s i z e range even though t h e f i n a l p a r t i c l e s may be l a r g e r t h a n t h o s e o f a c o l l o i d . R a p i d p r e -c i p i t a t i o n i s known to produce s t a b l e c o l l o i d s by c r y s t a l l i z -a t i o n about many c e n t r e s . A m i n e r a l h a v i n g c o l l o i d a l t e x t u r e c o u l d have been brought t o i t s s i t e of d e p o s i t i o n i n e l e c t r o -l y t i c s o l u t i o n and then d e p o s i t e d as a c o l l o i d by r a p i d p r e -c i p i t a t i o n . I t i s s i g n i f i c a n t t o note t h a t m a g n e t i t e showing such t e x t u r e i n the M e r r y Widow, K i n g f i s h e r , Y e l l o w K i d , and Kla a n c h d e p o s i t s i s found o n l y i n l i m e s t o n e . The c l o s e a s s o c i a t i o n w i t h t h i s " h i g h l y r e a c t i v e " r o c k may have been i n s t r u m e n t a l i n the f o r m a t i o n of c o l l o i d a l m a g n e t i t e by pro-moting r a p i d p r e c i p i t a t i o n . C o l l o f o r m m a g n e t i t e from the Sudbury d i s t r i c t , O n t a r i o , was d e s c r i b e d by Moore (1932) a l t h o u g h he d i d not suggest i t s o r i g i n . J e f f e r y (1960b) and J e f f e r y and S t e v e n -son (1961) d e s c r i b e d " n o d u l e s " o f c o l l o f o r m m a g n e t i t e found i n t a l u s i n the M e r r y Widow and K i n g f i s h e r d e p o s i t s and sug-g e s t e d a c o l l o i d a l o r i g i n f o r such m a g n e t i t e a l t h o u g h t h e y d i d not e l a b o r a t e . The p r e s e n t a u t h o r observed b o t r y o i d a l m a g n e t i t e i n p l a c e not o n l y i n the K i n g f i s h e r but a l s o i n the K l a a n c h d e p o s i t . In both d e p o s i t s i t o c c u r s i n l i m e s t o n e i n or near a p o s t - o r e f a u l t i n w h i c h m a g n e t i t e fragments have been cemented by c a l c i t e . In most cases t h e fragments are -7b,-surrounded by a r i m of c o a r s e l y c r y s t a l l i n e m a g n e t i t e . I t i s s u g g e sted t h a t s o l u t i o n s w h i c h deposited, t h e c a l c i t e cement a l s o d i s s o l v e d and r e p r e c i p i t a t e d m a g n e t i t e around the f r a g -ments. C o l l o i d a l m a g n e t i t e c o u l d have formed a t t h i s t i m e because t h e r e i s a p p a r e n t l y no reason why c o l l o i d a l a ggre-g a t i o n and e l e c t r o l y t i c p r e c i p i t a t i o n cannot take p l a c e a t the same time (Bastin,195>0,p .22). The e x t e r n a l s u r f a c e s of c o l l o f o r m m a g n e t i t e a r e always convex toward s u r r o u n d i n g c a l c i t e . C o l l o i d a l p a r t i c l e s of ma g n e t i t e may have c o a g u l a t e d i n open spaces between e a r l i e r b r e c c i a t e d m a g n e t i t e and then the r e m a i n i n g space was f i l l e d w i t h c a l c i t e . D e p o s i t i o n of c a l c i t e sometimes over lapped t h a t of m a g n e t i t e as shown by "c o n f o r m a b l e " l a y e r s of c a l c i t e i n c o l l o f o r m m a g n e t i t e . C o a g u l a t i o n of m a g n e t i t e p a r t i c l e s was p r o b a b l y brought about by n e u t r a l i z i n g an e l e c t r i c charge on t h e p a r t i c l e s . T h i s c o u l d have been e f f e c t e d by e l e c t r o l y t e s i n a h y d r o t h e r m a l s o l v e n t . The magnetic p r o p e r t i e s of m a g n e t i t e p a r t i c l e s i n some way may have a l s o a i d e d c o a g u l a t i o n . The e f f e c t of temperature on c o l l o i d a l d i s p e r s i o n s i s not f u l l y u n d e r s t o o d but Hartman ( 19U-7, p. 283) noted t h a t , i n g e n e r a l , the s t a b i l i t y of a s o l u t i o n i n c r e a s e s w i t h r i s i n g temperature i . e . the tendency t o c o a g u l a t e i s g r e a t e r at lower temper-a t u r e s . - 7 5 -The p r o p e r t i e s of m a g n e t i t e s o l have not been f u l l y i n v e s t i g a t e d . S e v e r a l t e x t s on c o l l o i d c h e m i s t r y do not mention m a g n e t i t e nor i s the m i n e r a l d i s c u s s e d i n many papers by B o y d e l l and by L i n d g r e n on c o l l o i d s as a p p l i e d to ore d e p o s i t s . C o l l o i d a l f e r r i c h y d r o x i d e i s w e l l known but i n t h e samples o f c o l l o f o r m m a g n e t i t e s t u d i e d t h e r e i s no i n d i c a t i o n t h a t such m a g n e t i t e has r e p l a c e d an e a r l i e r h y d r o x i d e ; no u n r e p l a c e d remnants o f g o e t h i t e , h e m a t i t e , or o t h e r m i n e r a l were found i n more than two dozen specimens examined. L i n d l e y and Brown (1958) d i s c o v e r e d c o l l o i d a 1 - s i z e d m a g n e t i t e (50 mu) i n the o i l system of a steam t u r b i n e . In a m i x t u r e of c o l l o i d a l m a g n e t i t e and o i l , no d e p o s i t i o n t o o k p l a c e . However, when o n l y 1% b r i n e was added as an e m u l s i o n , the m a g n e t i t e p a r t i c l e s formed aggregates around t h e f i n e d r o p l e t s of water i n the medium. The NaCl e l e c t r o l y t i c s o l u t i o n p r o b a b l y a c t e d as a p e c t i z i n g agent which f l o c c u l a t e d m a g n e t i t e by n e u t r a l i z i n g the charge on c o l l o i d a l p a r t i c l e s . In some r e s p e c t s , t h e n , m a g n e t i t e s o l behaves as an o r d i n a r y l y o p h o b i c s o l . C o l l o f o r m aggregates o f o t h e r " h i g h t e m p e r a t u r e " m i n e r a l s such as garnet and m o l y b d e n i t e have been d e s c r i b e d by Vakhrushev (19 6 1) i n f e r r u g i n o u s s k a r n s o f w e s t e r n S i b e r i a . C o l l o f o r m garnet o f the a n d r a d i t e - g r o s s u l a r i t e type i s the main c o n s t i t u e n t of t h i s s k a r n . Vakhrushev c o n c l u d e d -76-t h a t :;col l o f o r m garnet formed as the r e s u l t o f a c t i v i t y of t h e r e s i d u a l h y d r o t h e r m a l s o l u t i o n s a f t e r t h e f o r m a t i o n o f s k a r n . C r y s t a l l i n e g arnet was d i s s o l v e d and r e d e p o s i t e d i n the form of f i n e - g r a i n e d and c r y p t o c r y s t a 1 1 i n e a g g r e g a t e s . The p r o c e s s of f o r m a t i o n of c o l l o f o r m g a r n e t d e s c r i b e d by Vakhrushev i s almost i d e n t i c a l t o t h a t proposed by t h e p r e s e n t a u t h o r f o r c o l l o f o r m m a g n e t i t e . The w r i t e r c o n c l u d e s : (1) c o l l o f o r m m a g n e t i t e i n the K i n g f i s h e r and K l a a n c h d e p o s i t s was d e p o s i t e d from a c o l l o i d a l d i s p e r s i o n (2) c o l l o f o r m m a g n e t i t e i s a s e c o n d a r y f e a t u r e brought about by r e d e p o s i t i o n of e a r l i e r m a g n e t i t e i n a p o s t -ore f a u l t now cemented by c a l c i t e (3) the s o l u t i o n s which c a r r i e d t h i s c a l c i t e d i s s o l v e d some of the c r y s t a l l i n e m a g n e t i t e of t h e b r e c c i a t e d o r e i n the f a u l t and (I4.) t h i s d i s s o l v e d m a g n e t i t e was p r e c i p i t a t e d b oth as an e l e c t r o l y t i c c r y s t a l l i n e a g g r e g a t e and a l s o as a c o l l o i d . P y r i t e P y r i t e o c c u r s i n a v a r i e t y of forms and i s r e l a t i v e l y abundant i n most ro c k a s s o c i a t e d w i t h c o n t a c t metasomatic m a g n e t i t e d e p o s i t s . A n h e d r a l p y r i t e i s s c a t t e r e d throughout m a s s i v e m a g n e t i t e and s k a r n ; e u h e d r a l forms a r e more abundant i n l i m e s t o n e . S t r i a t e d cubes, o c t a h e d r o n s , p y r i t o h e d r o n s , or -77-c o m b i n a t i o n s o f these have been found. S e v e r a l d e p o s i t s c o n t a i n minor amounts of p y r i t e as r o u g h l y c i r c u l a r p l a t e s about 1/16 i n c h i n t h i c k n e s s and one i n c h i n d i a m e t e r . These p l a t e s have b o t h a random and an o r i e n t e d h a b i t . In p o l i s h e d s e c t i o n , these p l a t e s are seen t o be composed o f s e v e r a l l a r g e p y r i t e g r a i n s . Many a r e a n i s o t r o p i c but X-ray d i f -f r a c t i o n p a t t e r n s showed the g r a i n s t o be p y r i t e and not marcas i t e . C h a l c o p y r i t e A n h e d r a l masses of c h a l c o p y r i t e are found i n a l m o s t e v e r y d e p o s i t . In some d e p o s i t s d i s s e m i n a t e d b l e b s and patches i n m a g n e t i t e appear t o have been d e p o s i t e d e s s e n t i a l l y con-temporaneously w i t h the i r o n o x i d e ; i n o t h e r d e p o s i t s , or i n d i f f e r e n t p a r t s of the same d e p o s i t , c h a l c o p y r i t e can be seen v e i n i n g m a g n e t i t e and s k a r n o r f i l l i n g vugs i n s k a r n . V e r y minor amounts are e x s o l v e d i n s p h a l e r i t e . C h a l c o p y r i t e i n the Texada I s l a n d , M e r r y Widow, and Tassoo d e p o s i t s c a r r i e s c o n s i d e r a b l e amounts of s i l v e r and minor amounts o f g o l d . Eastwood and M e r r e t t (1961,pp.96-97) su g g e s t e d t h a t , i n the M e r r y Widow d e p o s i t , s i l v e r i s p r e f e r -e n t i a l l y c o n c e n t r a t e d i n c h a l c o p y r i t e but g o l d i s r e l a t e d t o the t o t a l s u l p h i d e c o n t e n t o f t h e o r e . I t p r o b a b l y a l s o occurs i n o t h e r s u l p h i d e m i n e r a l s . - 7 8 -P y r r h o t i t e T h i s m i n e r a l o c c u r s i n minor amounts i n much t h e same manner as c h a l c o p y r i t e . I t i s found w i t h c h a l c o p y r i t e , p y r i t e , and a r s e n o p y r i t e . S p h a l e r i te S m a l l amounts o f s p h a l e r i t e are f o u n d w i t h o t h e r s u l p h i d e m i n e r a l s i n s e v e r a l d e p o s i t s . I t a l s o o c c u r s as e x s o l u t i o n b o d i e s i n c h a l c o p y r i t e , A r s e n o p y r i t e A r s e n o p y r i t e i s found o n l y i n the M e r r y Widow d e p o s i t and i s a s s o c i a t e d w i t h o t h e r s u l p h i d e m i n e r a l s i n t h a t d e p o s i t CobaIt i t e C o b a l t i t e o c c u r s i n v e r y s m a l l amounts i n m a g n e t i t e and s k a r n i n t h e Merry Widow d e p o s i t . - 7 9 -CHAPTER I I I - ENVIRONMENT OF ORE DEPOSITION C o n f i n i n g p r e s s u r e An e s t i m a t e of the c o n f i n i n g p r e s s u r e d u r i n g s k a r n -i f i c a t i o n and ore d e p o s i t i o n can be deduced from the depth of i n t r u s i on ;>of the a d j a c e n t p l u t o n . From a s t u d y of g r a n i t i c p l u t o n s , p a r t i c u l a r l y of t h e i r i n t e r n a l and e x t e r n a l s t r u c t u r e s , B u d d i n g t o n (195>9) d e f i n e d t h r e e depth zones of g r a n i t e emplacement. These zones and t h e i r approximate depth and temperature l i m i t s a r e : (1) epizone - extends from the s u r f a c e t o s i x m i l e s , commonly f o u r m i l e s . The maximum temperature o f c o u n t r y rocks b e f o r e i n t r u s i o n i s about 300° C. (2) mesozone - about f o u r t o t e n m i l e s i n d e p t h j a temperature range b e f o r e i n t r u s i o n of 250-5>00°C. (3) catazone - seven t o t w e l v e m i l e s (or more); temperature range 5>00-700°C. Buddington p l a c e d the e n t i r e "Coast Range b a t h o l i t h " i n the mesozone. However, t h i s " b a t h o l i t h " i s now c o n s i d e r e d an i n t r u s i v e complex composed of w i d e l y d i f f e r e n t c o m p o s i t i o n s and ages. The i s o l a t e d g r a n i t i c s t o c k s and s m a l l b a t h o l i t h s on Vancouver, Texada, and Moresby I s l a n d s must each be a s s i g n e d to a depth zone on i t s own m e r i t s . In -80-consequence, the w r i t e r w i l l attempt t o c l a s s i f y i n d i v i d u a l i n t r u s i o n s a d j a c e n t t o m a g n e t i t e d e p o s i t s a c c o r d i n g t o Buddington's c r i t e r i a . Data have been used from the a u t h o r ' s o b s e r v a t i o n s i n mine areas and from i n f o r m a t i o n gathered by o f f i c e r s o f the B.C. Department o f Mines d u r i n g r e g i o n a l mapping. Bu d d i n g t o n d i s c u s s e d s e v e r a l c r i t e r i a f o r each depth zone, but not a l l o f these c r i t e r i a c a r r y equal w e i g h t . Those c o n s i d e r e d by the p r e s e n t w r i t e r t o be f a i r l y d i a g n o s t i c and t o be a p p l i c a b l e i n the p r e s e n t s t u d y a r e g i v e n below (para p h r a s e d from Buddington,1 9 ^ 9 ) : E p i zone 1. The p l u t o n s a r e l a r g e l y or w h o l l y d i s c o r d a n t . 2. The p l u t o n s are c l o s e l y connected w i t h v o l c a n i c r o c k of the same age. 3. C o u n t r y r o c k , o u t s i d e of the c o n t a c t metamorphic z-orje, i s r e l a t i v e l y unmetamorphosed. LL. E a r l i e r members of the i n t r u s t i o n s show c h i l l e d b o r d ers a g a i n s t c o u n t r y r o c k s . 5. M i a r o l i t i c t e x t u r e i s common. 6. Granophyre i s p r e s e n t . 7 . The p l u t o n i s accompanied by e x p l o s i o n or i n t r u s i o n b r e c c i a . 8. The i n t r u s i o n s a r e accompanied by c o n t a c t metamorphism or metasomatism. 9. D e f o r m a t i o n o f c o u n t r y r o c k i s i n p a r t caused by f o r c e f u l i n t r u s i o n of the magma. 10. The i n t r u s i v e r o c k s are homophanous. Mesozone 1. Metamorphism of the c o u n t r y r o c k has not exceeded th e green s c h i s t or e p i d o t e - a m p h i b o l i t e f a c i e s . 2. There i s a complex emplacement r e l a t i o n s h i p between the i n t r u s i o n and c o u n t r y r o c k . C o n t a c t s a r e i n p a r t c o n c o r d a n t , i n p a r t d i s c o r d a n t . -81-3. F o l i a t i o n i s common i n the o u t e r zone o f the p l u t o n . LL. S c h i s t o s e s t r u c t u r e i s common i n b o r d e r i n g c o u n t r y r o c k . Catazone 1. C o u n t r y r o c k i s metamorphosed t o g r a n u l i t e or orthogne i s s. 2. There i s an e x t e n s i v e m i g m a t i t e zone b o r d e r i n g the p l u t o n . 3. G n e i s s i c s t r u c t u r e i s w i d e s p r e a d w i t h i n the i n t r u s i o n . In T a b l e 9 these c r i t e r i a a r e a p p l i e d t o p l u t o n s a d j a c e n t t o m a g n e t i t e d e p o s i t s . The Coast Copper and. Jedway s t o c k s , the s m a l l e s t , appear t o be o f the e p i z c n e t y p e . E v i d e n c e i s i n c o n c l u s i v e f o r the Z e b a l l o s and Kennedy Lake i n t r u s i o n s but the Quinsam, G i l l i e s , and Nim p k i s h i n t r u s i o n s have c h a r a c t e r i s t i c s t r a n s i t i o n a l between t h o s e o f the ep l z o n e and mesozone. C o n s e q u e n t l y , a r e a s o n a b l e e s t i m a t e of de p t h of i n t r u s i o n of t h e s e seven p l u t o n s and t h e i r m a g n e t i t e de-p o s i t s i s LL .5 m i l e s . The l i t h o s t a t i c p r e s s u r e at t h i s depth i s near 2000 b a r s . An independent e s t i m a t e o f c o n f i n i n g p r e s s u r e f o r the Coast Copper s t o c k d u r i n g o r e d e p o s i t i o n i s made p o s s i b l e by s t u d y i n g phase r e l a t i o n s of c o e x i s t i n g m i n e r a l s i n the M e r r y Widow d e p o s i t . P y r i t e , p y r r h o t i t e , and a r s e n o p y r i t e c o e x i s t w i t h m a g n e t i t e and o t h e r s u l p h i d e s . C l a r k (1959/60) has shown t h a t the c o m p o s i t i o n o f a r s e n o p y r i t e i s a f u n c t i o n of temperature a n d _ c o n f i n i n g p r e s s u r e . I f t h e tem p e r a t u r e of -82-T a b l e 9 C l a s s i f i c a t i o n o f seven i n t r u s i o n s i n t o the t h r e e depth zones  of B uddington (1909) Q u i n - G i l l i e s Coast Kennedy Zeb- Nimp- Jedway sam Copper Lake a l i o s k i s h 1 . X X X 2. 3. x x x x Epizo n e I I . c h a r a c t e r - 5>. x i s t i c s 6. 7. x? 8. x x 9. • x x 10. x x x x x x x 1. x x x x Mesozone 2. x x x x c h a r a c t e r - 3-i s t i cs I I . Catazone 1. c h a r a c t e r - 2. i s t i c s 3• f o r m a t i o n o f a r s e n o p y r i t e can be e s t i m a t e d by independent means, th e n the a r s e n o p y r i t e c o m p o s i t i o n (as deduced by the (131) i n t e r p l a n a r s p a c i n g s ) y i e l d s an e s t i m a t e o f c o n f i n i n g p r e s s u r e . An average t e m p e r a t u r e of 5l5°C was o b t a i n e d from two samples o f p y r i t e and p y r r h o t i t e c o e x i s t i n g w i t h a r s e n o p y r i t e i n t h i s orebody (Table 10, nos. 6 and 7) . The a r s e n o p y r i t e has a (131) i n t e r p l a n a r s p a c i n g of I.63IO 1 - 8 3 -O.OOO^A5. I f the temperature d e r i v e d from the p y r i t e - p y r r h o t i t e r e l a t i o n i s t h e temperature of f o r m a t i o n of c o e x i s t i n g a r s e n o -p y r i t e , the c o n f i n i n g p r e s s u r e by C l a r k ' s .method would be 2600 b a r s . C l a r k ' s c u r v e s f o r low (131) i n t e r p l a n a r s p a c i n g s i n a r s e n o p y r i t e are t e n t a t i v e so t h a t l i m i t s o f e r r o r may be ilOOO bars ( C l a r k , w r i t t e n communication, I96I4.). In the d i s c u s s i o n s to f o l l o w , a c o n f i n i n g p r e s s u r e of 2000 bars w i l l be used f o r the purpose o f c a l c u l a t i n g l i m i t s of o t h e r v a r i a b l e s . Temperature of the p l u t o n The m e l t i n g temperature of an igneous r o c k i s a f u n c t i o n of many v a r i a b l e s . Two o f the more i m p o r t a n t are r o c k c o m p o s i t i o n and water vapour p r e s s u r e . Smith (1963,p.201) c a l c u l a t e d t h a t , at c o n s t a n t c o n f i n i n g p r e s s u r e , the temperatures of complete m e l t i n g of d r y igneous rocks of the g r a n i t e - g a b b r o s e r i e s v a r y i n a l i n e a r manner w i t h t h e p e r c e n t a g e of s i l i c a . The e f f e c t o f p r e s s u r e on d r y igneous rocks i s t o r a i s e s l i g h t -l y t h e i r m e l t i n g temperatures (Smith,1963,p.202). When heated under w a t e r vapour p r e s s u r e , however, rocks melt at c o n s i d e r -a b l y lower temperatures but i t i s r e a s o n a b l e t o assume t h a t minimum m e l t i n g temperatures o f "wet" r o c k s , at c o n s t a n t water -&v p r e s s u r e , a l s o w i l l v a r y l i n e a l l y w i t h s i l i c a c o n t e n t . B e g i n n i n g - o f - m e I t i n g c u r v e s of g r a n i t e ( c o n t a i n i n g 72% S i C ^ ) a n d ' o l i v i n e t h o l e i i t e ( c o n t a i n i n g 1+9% SiCV)) i n the p r e s e n c e o f water vapour a r e shown i n F i g u r e 9 (Yoder and T i l l e y , 1962). These cur v e s a r e v e r y n e a r l y p a r a l l e l and the a u t h o r has drawn an i n t e r m e d i a t e m e l t i n g c u r v e f o r a r o c k of i n t e r m e d i a t e com-p o s i t i o n ( 6 2% S i G ^ ) . S i x p l u t o n s a d j a c e n t t o m a g n e t i t e d e p o s i t s ( p o i n t 'X', F i g . 1+) have an average SiC>2 c o n t e n t of 62 .5%. T h e i r average b e g i n n i n g - o f - m e l t i n g c u r v e would be expected t o f a l l c l o s e t o the i n t e r m e d i a t e m e l t i n g c u r v e shown i n F i g u r e 9. Assuming t h i s "average" magma t o be s a t u r a t e d w i t h water a t the time of intrusio-n.^.aad-.that water was the major v o l a t i l e c o n s t i t u e n t , t h e n water p r e s s u r e i n the magma would e q u a l c o n f i n i n g p r e s s u r e . T h i s p r e s s u r e has been e s t i m a t e d as about 2000 bars and, u s i n g t h e i n t e r m e d i a t e curve of F i g u r e 9, r o c k of c o m p o s i t i o n 'X' would have a minimum m e l t i n g temperature of 780°C. Large v a r i a t i o n s i n wat e r vapour p r e s s u r e do not a p p r e c i a b l y a l t e r m e l t i n g t e m p e r a t u r e . For example, i f t h e p r e s s u r e g i v e n above v a r i e s as much as ilOOO b a r s , t h i s w i l l cjhange the minimum m e l t i n g temperature by o n l y ±lj.0oC. The gabbro phase o f the, C o a s t Copper s t o c k has a s i l i c a c o n t e n t of about 1+7% and was not i n c l u d e d i n c a l c u l a t i n g average 'X'. U s i n g the b a s a l t curve i n F i g u r e 9, a minimum m e l t i n g t e m p e r a t u r e of 880°C and 2000 bars water p r e s s u r e i s i n d i c a t e d 500 600 700 800 900 1000 1100 Temperature, °C. FIGURE 9 Beginnin^-of-melting curves of granite and olivine tholeiite (from Yoder and Tilley, 1962). Intermediate curve (dotted line) obtained by interpolation. -86-f o r such gabbro. Data from Yoder and T i l l e y ( 1962,pp.I4J4.9 et seq.) i n d i c a t e t h a t pyroxene i n m a f i c rocks i s s t a b l e o n l y at water p r e s s u r e s lower than II4.OO b a r s . At h i g h e r water p r e s s u r e s , amphibole i s formed. C o n s e q u e n t l y , pyroxene gabbro of t h e Coast Copper s t o c k may have formed at water p r e s s u r e s s l i g h t l y l e s s than 2000 b a r s . Temperature of s k a r n i f i c a t i o n I t seems r e a s o n a b l e to c o n c l u d e t h a t the maximum tempe r a t u r e of s k a r n i f i c a t i o n i s t h e temperature of the i n t r u d i n g magma. Other e v i d e n c e , t o be d e s c r i b e d below, i s r e q u i r e d t o e s t a b l i s h a minimum t e m p e r a t u r e . I n t r u s i o n s a d j a c e n t t o mag n e t i t e d e p o s i t s i n c o a s t a l B r i t i s h Columbia are not i n c o n t a c t w i t h p e l i t i c " i n d i c a t o r " r o c k s w h i c h would p r o v i d e a gui d e t o the degree of metamorphism reached i n the s k a r n c o n t a c t a u r e o l e s . S i l i c a - f r e e l i m e s t o n e and a n d e s i t i c v o l c a n i c rocks a r e the c o u n t r y r o c k s and, o t h e r than b e i n g r e c r y s t a 1 1 i z e d , have been o n l y s l i g h t l y a f f e c t e d by thermal metamorphism. C o n s i d e r i n g t h e i r p r o x i m i t y t o i n t r u s i o n s , however, c o n t a c t s k a r n s p r o b a b l y formed i n the innermost zone of c o n t a c t metamorphism, the temperature range o f w h i c h . - 8 7 -i s l a r g e l y determined by the m e l t i n g temperature range o f a d j a c e n t i n t r u s i o n s . The innermost zone o f a g r a n i t e c o n t a c t a u r e o l e , the hornblende h o r n f e l s f a c i e s ( F y f e , T u r n e r , a n d Verhoogen, 1 9 5 8 ,pp.2 0 5 - 2 1 1), approaches the lower l i m i t of magmatic t e m p e r a t u r e s . The lower and upper temperature l i m i t s of the h o r n b l e n d s h o r n f e l s f a c i e s a r e about 300°C. and 5 0 0 ° C , r e s p e c t i v e l y , under " d r y " c o n d i t i o n s . With s i x k i l o b a r s water p r e s s u r e , t h e s e l i m i t s i n c r e a s e to about 5>00°C. and 700°C. ( I b i d , p . 2 3 7 ) . C o n t a c t a u r e o l e s s u r r o u n d i n g gabbro s t o c k s , on the o t h e r hend, are commonly of the pyroxene h o r n f e l s f a c i e s w i t h t e m p e r a t u r e l i m i t s of about 500-1000°C. ("dry") and 700-1100°C. ( p H 2 0 = 6 k b . ) ( I b i d , p p . 2 1 1 - 2 1 3 ; 2 3 7 ) . The "average" i n t r u s i o n c o n s i d e r e d i n t h i s s t u d y i s of q u a r t z d i o r i t e c o m p o s i t i o n ( p o i n t 'X', F i g . I4.) . A c o n t a c t a u r e o l e a d j a c e n t to such an i n t r u s i o n would have a t e m p e r a t u r e range i n t e r m e d i a t e between t h a t of h o r n b l e n d e h o r n f e l s and pyroxene h o r n f e l s f a c i e s . I f an average c o n f i n i n g p r e s s u r e o f 2000 bars i s a c c e p t e d (see p r e c e d i n g s e c t i o n ) , then s k a r n formed i n t h i s c o n t a c t a u r e o l e at about 700°C. ( F y f e , T u r n e r , a n d Verhoogen, 1 9 5 8,Fig. 1 0 7,p . 2 3 7 ) . E x p e r i m e n t a l l y - d e t e r m i n e d s t a b i l i t y r e l a t i o n s o f the i n d i v i d u a l m i n e r a l s c o m p r i s i n g s k a r n w i l l a l s o a i d i n e s t a b l i s h i n g temperature l i m i t s of s k a r n i f i c a t i o n . Garnet - 8 8 -o f the . a n d r a d i t e - g r o s s u l a r i t e s e r i e s i s the most abundant s k a r n m i n e r a l . A n d r a d i t e and g r o s s u l a r i t e have been formed hydrotherma 11 y from t h e i r c o n s t i t u e n t o x i d e s a t 500°C and 1+00 atmospheres ( F l i n t . M c M u r d i e , and W e l l s , 19^ 4-1) • Attempts t o s y n t h e s i z e t h e s e m i n e r a l s at lower t e m p e r a t u r e s f a i l e d and experiments were a p p a r e n t l y not made a t temper a t u r e s h i g h e r than 500°C. F u r t h e r work showed that.) a'complete s o l i d s o l u t i o n s e r i e s e x i s t s between g r o s s u l a r i t e , h y d r o g r o s s u l a r i t e , " h y d r o a n d r a d i t e " , and a n d r a d i t e . P i s t o r i u s and Kennedy ( i 9 6 0 ) showed t h a t , i n the presence of excess s i l i c a , g r o s s u l a r i t e i s s t a b l e above 780°C and above 15 k i l o b a r s water p r e s s u r e ( F i g . 1 0 a ) . In a s i l i c a - p o o r environment, however, t h e p r e s s u r e of f o r m a t i o n of a l l anhydrous g a r n e t s i s lower ( F y f e , T u r n e r , a n d Verhoogen, 1 9 5 8 ,p. 1 ^ 6 ) . For example, Yoder (1950,p.21+5; 1951+,p. 120) showed t h a t g r o s s u l a r i t e w i t h o u t q u a r t z i s s t a b l e a t 800°C under o n l y 2000 bars water p r e s s u r e ( F i g . 1 0 b ) . A s m a l l mol p e r c e n t of a l m a n d i t e i s p r e s e n t i n s k a r n g a r n e t s ( F i g . 8) and a t 2000 bars water p r e s s u r e , the t h e r m a l s t a b i l i t y l i m i t of t h i s m i n e r a l i s 830°C; at a t m o s p h e r i c p r e s s u r e a l m a n d i t e i s not s t a b l e above 785°C. Above i t s s t a b i l i t y r ange, t h i s m i n e r a l breaks down t o i r o n - c o r d i e r i t e , f a y a l i t e , and h e r c y n i t e . The lower s t a b i l i t y range o f pH 2 0, kilobars -68" -90-a l m a n d i t e i s not known (Yoder, 1 9 5 5 )• As n e i t h e r h y d r o g a r n e t s nor d e c o m p o s i t i o n p r o d u c t s of a l m a n d i t e and g r o s s u l a r i t e have been found i n t h e skarns s t u d i e d , tihe t e m p e r a t u r e of f o r m a t i o n of pure g r o s s u l a r i t e a t 2000 bars water p r e s s u r e would be about 800°C. High P-T data are not a v a i l a b l e f o r a n d r a d i t e and t h e s e f i g u r e s a r e t e n t a t i v e l y e x t r a p o l a t e d t o i n c l u d e a l l members of the g r a n d i t e s e r i e s . G r a n d i t e g a r n e t i n c o n t a c t zones i s g e n e r a l l y b i r e -f r i n g e n t . S e v e r a l i n v e s t i g a t o r s ( W r i g h t , 1915; S t o s e and G l a s s , 1 9 3 8 ; A l l e n and Fahey , 1 9 5 7 l Stone, 1 9 5 9 ) , f i n d i n g t h a t such garnet became i s o t r o p i c upon h e a t i n g to about 800°C., have suggested that b i r e f r i n g e n t garnet c o u l d be used as a crude g e o l o g i c thermometer. They c o n c l u d e d t h a t b i r e f r i n g e n t garnet had formed below, and i s o t r o p i c garnet above, 800°C, The o r i g i n of b i r e f r i n g e n t g a r n d i t e g a r n e t s has been d i s c u s s e d elsewhere i n t h i s paper and t h e i r use as g e o l o g i c thermometers has been q u e s t i o n e d . D i o p s i d e i s another common c o n s t i t u e n t o f s k a r n and i t s upper l i m i t of t h e r m a l s t a b i l i t y i s about 600°C. at a t m o s p h e r i c p r e s s u r e . Above t h i s temperature d i o p s i d e r e a c t s w i t h c a l c i t e to form a k e r m a n i t e (Bowen, 19U-0) . W i t h i n c r e a s i n g p r e s s u r e , the e q u i l i b r i u m t emperature o f t h i s r e a c t i o n i n c r e a s e s s t e a d i l y to 980°C. at 1000 atmospheres (Weeks , 1956, p. 2 5 9 , F i g .I4.), -91-the h i g h e s t P , T - c o n d i t i o n s f o r w h i c h thermodynamic data a r e a v a i l a b l e . The absence o f ak e r m a n i t e i n the skarns s t u d i e d p l a c e s an extreme upper l i m i t of 9 8 0 ° C . to the temp e r a t u r e of f o r m a t i o n of t h e s e s k a r n s . E p i d o t e i s a wid e s p r e a d s k a r n m i n e r a l and i s g e n e r a l l y the l a s t c a l c i u m - s i l i c a t e t o form. I t predominates i n the o u t e r (and presumably c o o l e r ) f r i n g e s of zoned d e p o s i t s . The approximate temperature of f o r m a t i o n of e p i d o t e was e s t i m a t e d t o be I L O O ° C . (1 atm.) by Str i n g h a m (19.52) based on p u b l i s h e d i n f o r m a t i o n a v a i l a b l e t o 1951• R e c e n t l y M e r r i n ( i 9 6 0 ) has extended t h e "apparent s t a b i l i t y c u r v e " of e p i d o t e to 7 0 0 ° C . at 5000 bars p r e s s u r e . A t 2000 b a r s , the upper s t a b i l i t y l i m i t of t h i s m i n e r a l , as deduced from h i s d a t a , i s 5 5 0 ° C . T h i s t e m p e r a t u r e , lower t h a n t h a t e s t i m a t e d f o r garnet and d i o p s i d e at t h e same p r e s s u r e , i s i n a c c o r d w i t h both t h e p o s i t i o n of e p i d o t e i n s k a r n p a r a g e n e s i s and i t s p e r i p h e r a l abundance. W o l l a s t o n i t e was found o n l y i n the P r e s c o t t d e p o s i t , Texada I s l a n d . The m i n e r a l o c c u r r e d i n a b l o c k of l i m e s t o n e surrounded by garnet s k a r n about 70 f e e t from q u a r t z monzonite. The p r e s e n c e o f w o l l a s t o n i t e i n d i c a t e s t h e temperature a t t h i s p l a c e r e a c h e d at l e a s t !L8 0 °C. T h i s i s the minimum temperature of f o r m a t i o n o f w o l l a s t o n i t e f r o m q u a r t z and - 9 2 -c a l c i t e (Barth, 1 9 ^ 2 ,pp. 2 8 6 - 2 8 7 ). With i n c r e a s i n g c a r b o n -d i o x i d e p r e s s u r e , the temperature of f o r m a t i o n r i s e s so t h a t at 5000 atmospheres the e q u i l i b r i u m t e m p e r a t u r e i s about 900°C. In c o n t a c t a u r e o l e s , r e a c t i o n s which produce metasomatic rocks i n l i m e s t o n e p r o b a b l y take p l a c e w i t h r a p i d p r o d u c t i o n of C O 2 . A r e l a t i v e l y h i g h CC>2 p r e s s u r e would r a i s e t h e e q u i l i b r i u m temperature of the q u a r t z - c a l c i t e r e a c t i o n . B a r t h ( 1 9 5 0 ,p.2 8 7 ) has s u g g e s t e d , however, t h a t , because CO 2 might be expected to p e r c o l a t e r a p i d l y away through semi-permeable r o c k c o v e r , p r e s s u r e would have l i t t l e e f f e c t on t h e s t a b i l i t y temperature of wo 1 l a s t o n i t e . Because of the u n c e r t a i n t y i n e s t i m a t i n g CO2 p r e s s u r e i n metasomatic r o c k s , t h e presence of w o l l a s t o n i t e can o n l y i n d i c a t e a minimum temperature of about 500°C. In the f o r e g o i n g d i s c u s s i o n t h e a s s u m p t i o n i s made t h a t c a r b o n d i o x i d e i s the o n l y v o l a t i l e p r e s e n t d u r i n g metasomatism. The presence of o t h e r f l u i d s , p a r t i c u l a r l y w a t e r , and t h e i r e f f e c t on e q u i l i b r i u m t e m p e r a t u r e s o f m i n e r a l s w i l l be d i s c u s s e d below. Lack of evidence of t h e r m a l d i s s o c i a t i o n 6f" Jt'k 1 c i t e a d j a c e n t t o i n t r u s i o n s i s o f l i t t l e use i n e s t i m a t i n g the temperature o f the c o n t a c t a u r e o l e s i n w h i c h s k a r n has formed. Less t h a n 30 atmospheres CC>2 p r e s s u r e p r e v e n t s d i s s o c i a t i o n at 1100°C. (Harker and T u t t l e , 1 9 5 5 ) . The e q u i l i b r i u m - 9 3 -temperature at one atmosphere i s 885°C. ( B i r c h et a l . , 191+2; Weeks,1 9 5 6 ) . In v i e w of the r a p i d i n c r e a s e of d i s s o c i a t i o n t e mperature w i t h s m a l l i n c r e a s e i n COg p r e s s u r e , i t i s u n l i k e l y t h a t c a l c i t e would d i s s o c i a t e i n an a u r e o l e a d j a c e n t t o a g r a n i t i c p l u t o n . Temperatures of f o r m a t i o n o f m i n e r a l s (and of m i n e r a l assemblages) from c a l c u l a t e d and e x p e r i m e n t a l e q u i -l i b r i u m curves must be c o n s i d e r e d maximum v a l u e s . Weeks (1956) p o i n t e d out t h a t the vapour phase p r e s e n t d u r i n g metamorphism and metasomatism of l i m e s t o n e i s p r o b a b l y a complex m i x t u r e of w a t e r , carbon d i o x i d e , and o t h e r c o n s t i t u e n t s . The p a r t i a l p r e s s u r e o f any component i n s o l u t i o n cannot n o r m a l l y be g r e a t e r t h a n t h e p r e s s u r e of the pure component under the same P , T - c o n d i t i o n s . A m i x t u r e of two or more components i n the vapour phase depresses the r e a c t i o n t e m p e r a t u r e a t any g i v e n p r e s s u r e . The e f f e c t of b i n a r y gas m i x t u r e s on c r y s t a l -vapour e q u i l i b r i u m t e m p e r a t u r e has been d i s c u s s e d f u r t h e r by Greenwood ( 1 9 6 1 / 6 2 ) . He has shown t h a t , i n the p r e s e n c e o f a vapour phase c o n s i s t i n g of carbon d i o x i d e and w a t e r a t con-s t a n t vapour p r e s s u r e , t h e e q u i l i b r i u m temperature o f r e a c t i o n s which r e l e a s e t h e s e f l u i d s as p r o d u c t s w i l l v a r y w i t h t h e c o m p o s i t i o n of t h e vapour phase. The e q u i l i b r i u m temperature of r e a c t i o n s i n w h i c h C 0 o i s r e l e a s e d w i l l r i s e as the mol I -91+-f r a c t i o n of CC>2 i n the vapour phase i n c r e a s e s ; whereas i n t h o s e r e a c t i o n s i n w h i c h i s r e l e a s e d , t h i s e q u i l i b r i u m t e mperature w i l l d e c r e a se as the CO2 content o f t h e v o l a t i l e phase i n c r e a s e s . For example, w i t h a vapour phase c o n s i s t i n g of 0 . 2 5 mol f r a c t i o n C 0 2 and 0 . 7 5 rnol f r a c t i o n H 2 0 at 1000 bars., c a l c i t e and q u a r t z are i n e q u i l i b r i u m w i t h w o l l a s t o n i t e and t h e vapour phase at 580°C. I f t h e c o m p o s i t i o n of t h i s vapour phase i s changed to 0 . 7 5 mol f r a c t i o n CO2 and 0 . 2 5 mol f r a c t i o n rlgO, t h e e q u i l i b r i u m t e m p e r a t u r e of the r e a c t i o n r i s e s t o 650°C. C o n s i d e r a t i o n o f t h e s t a b i l i t y of g r a n d i t e g a r n e t suggests a t e m p e r a t u r e o f 800°C. f o r s k a r n i f i c a t i o n but i n view of Weeks' and Greenwood's arguements, t h e temperature of 700°C, deduced from F y f e , Turner and Verhoogen, seems more r e a s o n a b l e . I n any c a s e , s k a r n appears t o have formed over a temperature range from about 700°C. ( f o r g a r n e t - d i o p s i d e ) t o 550°C. ( f o r e p i d o t e ) . Temperature of f o r m a t i o n of m e t a l l i c m i n e r a l s S u l p h i d e m i n e r a l s , i n g e n e r a l , were d e p o s i t e d con-temporaneously w i t h , or l a t e r t h an, m a g n e t i t e . Temperature d e t e r m i n a t i o n s based on c o e x i s t i n g s u l p h i d e s , t h e n , w i l l g i v e an e s t i m a t e o f the minimum temperature of m a g n e t i t e d e p o s i t i o n . -95-P y r i t e and p y r r h o t i t e c o e x i s t i n s e v e r a l d e p o s i t s and o f f e r an o p p o r t u n i t y to a p p l y the p y r i t e - p y r r h o t i t e geothermo-meter as d e s c r i b e d by A r n o l d (1962). By t h i s method, the metal c o n t e n t of p y r r h o t i t e c o e x i s t i n g i n e q u i l i b r i u m w i t h p y r i t e i s r e l a t e d to the t e m p e r a t u r e and p r e s s u r e o f c r y s t a l -l i z a t i o n . No c o r r e c t i o n o f c r y s t a l l i z a t i o n t e mperature i s n e c e s s a r y f o r p r e s s u r e s up t o 2000 bars at t e m p e r a t u r e s below 670°C. T h i s i s the p r e s s u r e e s t i m a t e d f o r d e p o s i t i o n o f the m a g n e t i t e d e p o s i t s c o n s i d e r e d so t h a t c o r r e c t i o n s f o r p r e s s u r e were not n e c e s s a r y . I n a p p l y i n g t h i s geothermometer, c e r t a i n assumptions are made: (a) t h a t p y r i t e and p y r r h o t i t e c o e x i s t e d i n e q u i l i b r i u m , (b) t h a t the p y r r h o t i t e c o m p o s i t i o n has not changed s i g n i f i c a n t l y d u r i n g subsequent g e o l o g i c a l events and (c) t h a t s m a l l c o n c e n t r a t i o n s o f elements i n s o l i d s o l u t i o n do not s i g n i f i c a n t l y a f f e c t the e q u i l i b r i u m r e l a t i o n s . I t i s not e s s e n t i a l t h a t t h e two m i n e r a l s be d e p o s i t e d s i m u l t a n e o u s l y . I f t h e y were d e p o s i t e d a t d i f f e r e n t times and were i n a p o s i t i o n t o r e a c t w i t h each o t h e r , i t i s assumed t h a t e q u i -l i b r i u m was a t t a i n e d a t the c o n d i t i o n s of d e p o s i t i o n of the l a t e r phase and the temperature measured w i l l be t h a t at which the l a t e r phase c r y s t a l l i z e d ( A r n o l d , 1 9 6 2 ) . In t h e specimens s t u d i e d , p y r i t e and p y r r h o t i t e a r e i n c o n t a c t w i t h one a n o ther and i t i s assumed t h e r e f o r e t h a t e q u i l i b r i u m was a t t a i n e d d u r i n g d e p o s i t i o n . - 9 6 -The c o m p o s i t i o n of p y r r h o t i t e from e i g h t specimens was determined by an X-ray s p a c i n g method which r e l a t e s d(102) t o c o m p o s i t i o n ( A r n o l d , 1 9 6 2 ) . The d (102) v a l u e s were d e t e r m i n -ed u s i n g a N o r t h American P h i l i p s d i f f T a c t o m e t e r w i t h Fe-r a d i a t i o n . The (220) r e f l e c t i o n o f f l u o r i t e (d = 1 .931 ; Swanson and Tatge ,195>3) was used as s t a n d a r d . The d i f f r a c t o -meter was s e t t o o s c i l l a t e t h r e e t o f i v e times over t h e r e g i o n t o be measured w i t h a goniometer r o t a t i o n of ^ / m i n u t e and c h a r t speed of one i n c h / d e g r e e . The c e n t r e s of g r a v i t y of the s t a n d a r d and unknown r e f l e c t i o n s were measured t o t h e n e a r e s t l / 3 0 i n c h ( t 0 . 0 5 ° 29) and t h e average o f t h r e e t o f i v e measurements was used i n c a l c u l a t i n g t e m p e r a t u r e . The u n c e r t a i n t y of t h e method i s t 50°C. M e t a l c o n t e n t s and e s t i m a t e d t e m p e r a t u r e s of c r y s t a l l i z a t i o n of e i g h t p y r r h o t i t e specimens a r e g i v e n i n Ta b l e 10. These t e m p e r a t u r e s , d e r i v e d from c o - e x i s t i n g p y r i t e and p y r r h o t i t e i n f o u r d i f f e r e n t c o n t a c t metasomatic d e p o s i t s and from d i f f e r e n t m i n e r a l o g i c a l zones, have a t o t a l d i f f e r e n c e of o n l y 160°C. A l l of t h e s e t e m p e r a t u r e s are lower t h a n t h e most p r o b a b l e t e m p e r a t u r e range of s k a r n i f i c a t i o n . F u r t h e r -more, t h e y are i n ac c o r d w i t h f i e l d o b s e r v a t i o n s t h a t m a g n e t i t e and s u l p h i d e s were formed l a t e r than s k a r n . -97-T a b l e 10 E s t i m a t e d 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 s o f p y r r h o t i t e c o e x i s t i n g w i t h p y r i t e No. Sample Lo c a t i on % metal Temp.(°C 1. NP-5-"- Paxton mine 1+7.1 380 2. NP-l-x 11 tt 1+7.1 380 3 . SP - 3 5 1 B Brynnor mine 14-7.1 380 k- L - 7 1 * Lake mine b .6.6 1490 5 . 1-103-::-it 11 1+6.5 510 6 . SP-282B Merry Widow mine 510 7 . SP-282D 11 11 11 [4.6.14. 520 8 . SP-11+1A Paxton mine 1+6.3 51+0 ;:-Specimens k i n d l y s u p p l i e d by R. G e o l o g i s t , Texada Mines L t d . P a t t e r s o n , Note: 1- 3 - Specimens c o l l e c t e d from Zone 3 h-•5 - L o c a l i t y unknown 6- 7 - Zone 1, M e r r y Widow mine 8 - T h i n s u l p h i d e l a y e r between s l i m e s t o n e (Zone 1+) . karn (Zone 2) and (Zones c o r r e s p o n d t o th o s e g i v e n i n Table I I ) In summary, the te m p e r a t u r e o f i n t r u s i o n seems t o have been 9 0 0 - 8 0 0°C > of s k a r n i f i c a t i o n 7 0 0 - 5 5 0 ° C , and d e p o s i t i o n o f m e t a l l i c m i n e r a l s 550-J+00°C. -98-P a r t i a l p r e s s u r e of oxygen OQ p r e s s u r e i n the p l u t o n The p a r t i a l p r e s s u r e o f oxygen i n a r o c k melt i s a f u n c t i o n of t o t a l vapour p r e s s u r e , t e m p e r a t u r e , and gas com-p o s i t i o n . I f the s i l i c a t e m e l t was i n e q u i l i b r i u m w i t h i t s v o l a t i l e c o n s t i t u e n t s at t h e time i t c r y s t a l l i z e d , the p r e s s u r e of must have been equal to t h e p a r t i a l p r e s s u r e of C>2 o f the t o t a l v o l a t i l e s . The p a r t i a l p r e s s u r e o f oxygen i n the melt determines t h e r a t i o o f f e r r o u s to f e r r i c o x i d e at a g i v e n t e m p e r a t u r e . T h i s oxygen p r e s s u r e can be computed i f t h r e e v a r i a b l e s are known: (a) t h e temperature of t h e s i l i c a t e melt a t t h e time o f c r y s t a l l i z a t i o n (b) the r e l a t i v e amounts o f Fe^O^ and FeO i n the system and (c) the e q u i l i b r i u m c o n s t a n t (K) f o r the r e a c t i o n 2 F e 2Oj^==± [j.FeO + 0 2 R e l a t i v e amounts of f e r r i c and f e r r o u s o x i d e a re determined by normal a n a l y t i c a l methods and Kennedy (I9I4.8) has measured • v a l u e s of K at v a r i o u s temperatures f o r a m e l t of b a s a l t i c c o m p o s i t i o n . The average o f s i x specimens from p l u t o n s ad-j a c e n t t o c o n t a c t m a g n e t i t e d e p o s i t s i s shown by p o i n t 'X' i n F i g u r e I4.. Rock of t h i s c o m p o s i t i o n a t 2 0 0 0 bars water p r e s s u r e -99-begins t o melt at 78O - 80°C. and c o n t a i n s 2.9 mol p e r c e n t FeO and 0 .73 mol p e r c e n t Fe^O^. Assuming a m e l t i n g temperature of 800°C. f o r purposes o f c a l c u l a t i o n the d i s s o c i a t i o n con-s t a n t (k) i s 302 x 1 0 " 9 (Kennedy, I9I4.8, p.51+0) . Under these c o n d i t i o n s , the p a r t i a l p r e s s u r e of oxygen i n melt of com-p o s i t i o n 'X' i s 21.1+ x 10 atmosphere. U s i n g v a l u e s of 10 . 5 mol p e r c e n t FeO, 1.92 mol p e r c e n t fe^p^, K = 138 x 10"^, m e l t i n g temperature = 900°C, the Coast Copper gabbro c o o l e d -12 i n e q u i l i b r i u m w i t h a p a r t i a l oxygen p r e s s u r e o f JL4.I • 9 x 10" atmosphere. Oxygen p r e s s u r e s such as those g i v e n above a re many o r d e r s o f magnitude l e s s than t h e p a r t i a l p r e s s u r e of oxygen produced by the d i s s o c i a t i o n o f wa t e r . For example, at 9 0 0°C, the p a r t i a l oxygen p r e s s u r e i s 3*62 x 10"^" atmos-phere (Kennedy, 191+-8, p.51+5) • Og p r e s s u r e i n the o r e - f o r m i n g f l u i d s The c a l c u l a t i o n of p a r t i a l p r e s s u r e s of gases i n e q u i l i b r i u m w i t h ore f l u i d s has been d i s c u s s e d by s e v e r a l a u t h o r s i n c l u d i n g H o l l a n d (1959), Krauskopf (1959), and Barnes and K u l l e r u d (1957a). Such c a l c u l a t i o n s g e n e r a l l y i n v o l v e d e t e r m i n a t i o n of e q u i l i b r i u m p r e s s u r e s f o r v a r i o u s l i m i t i n g r e a c t i o n s at v a r i o u s t e m p e r a t u r e s . - 1 0 0 -D u r i n g the f o r m a t i o n of m a g n e t i t e d e p o s i t s , t h e upper l i m i t of oxygen p r e s s u r e i s d e f i n e d by t h e r e a c t i o n : 2Fe 30 [ 4_ + i 0 2 T T ^ > 3 F e 2 0 3 An i n c r e a s e i n 0 2 p r e s s u r e above the e q u i l i b r i u m p r e s s u r e w i l l r e s u l t i n f o r m a t i o n of h e m a t i t e . The extreme lower l i m i t of oxygen p r e s s u r e i n ma g n e t i t e d e p o s i t s i s governed by the r e a c t i o n : F e 3°b rv X - 3 F e + 2 0 2 At c o n s t a n t 0 2 p r e s s u r e , i n c r e a s i n g temperature r e s u l t s i n r e d u c t i o n o f i r o n o x i d e s . C o n s e q u e n t l y , i f t h e te m p e r a t u r e of m a g n e t i t e d e p o s i t i o n can be e s t i m a t e d by independent means, the absence of n a t i v e i r o n or h e m a t i t e i n a d e p o s i t w i l l d e f i n e the maximum p o s s i b l e range o f 0 2 p r e s s u r e a t t h a t t e m p e r a t u r e . The f i e l d s of s t a b i l i t y of i r o n o x i d e s have been i n v e s t i g a t e d by H o l l a n d (1959) and from h i s graphs t h e oxygen p r e s s u r e d u r i n g d e p o s i t i o n of c o n t a c t m a g n e t i t e d e p o s i t s can be e s t i m a t e d . The temperature o f d e p o s i t i o n o f ore i n these d e p o s i t s has been e s t i m a t e d to f a l l i n the range I L O O - 5 5 0 ° C. (Table 1 0 ) . T h i s temperature range, t o g e t h e r w i t h t h e absence of h e m a t i t e or n a t i v e i r o n i n m a g n e t i t e - 1 7 d e p o s i t s , p e r m i t s a p o s s i b l e oxygen p r e s s u r e range of 1 0 t o 1 0 ~ ^ atmosphere i n e q u i l i b r i u m w i t h m a g n e t i t e . T h i s - 1 0 1 -wide range i n oxygen p r e s s u r e may e x p l a i n the w i d e s p r e a d o c c u r r e n c e of ma g n e t i t e as the main i r o n - b e a r i n g m i n e r a l i n c o n t a c t d e p o s i t s . P a r t i a l p r e s s u r e s o f oxygen i n the ore f l u i d s a r e c o n s i d e r a b l y lower t h a n t h o s e i n magmatic f l u i d s i n e q u i l i b r i u m w i t h an a d j a c e n t p l u t o n . . I n those d e p o s i t s c o n t a i n i n g c o e x i s t i n g p y r i t e , p y r r h o t i t e , and m a g n e t i t e , the oxygen p r e s s u r e i s f i x e d , at a g i v e n t e m p e r a t u r e , by e q u i l i b r i u m i n the r e a c t i o n s 6 F e S + l i 0 2 ^ = £ ^ 2 F E 3 ° i 4 . + 3 S 2 and 3 F e S 2 + 2 Q 2 ^ ^  Fe^O^ + 3 S 2 At ILOO C , the e q u i l i b r i u m oxygen p r e s s u r e i s 10" atmosphere; 18 a t 550°C., i t i s 10" atmosphere. These p r e s s u r e s f a l l w i t h -i n the maximum p o s s i b l e range determined f o r m a g n e t i t e i n the absence of n a t i v e i r o n or h e m a t i t e . C o e x i s t e n c e o f the t h r e e phases m a g n e t i t e , p y r i t e , p y r r h o t i t e , narrows the range o f p o s s i b l e oxygen p r e s s u r e i n e q u i l i b r i u m w i t h t h e s e m i n e r a l s d u r i n g ore f o r m a t i o n . -102-P a r t i a l p r e s s u r e o f s u l p h u r As most c o n t a c t m a g n e t i t e d e p o s i t s commonly c o n t a i n p y r i t e , t h e minimum s u l p h u r p r e s s u r e i n such d e p o s i t s , i n the 8 3 temperature range l+OO-^O C , must have been 10" t o 10~^ atmosphere (Hoi l a n d , 191+8, p. 189) • Lower s u l p h u r p r e s s u r e s would r e s u l t i n f o r m a t i o n of p y r r h o t i t e a c c o r d i n g to t h e r e a c t i o n 2FeS + S 2 ^ ^ 2 F e S 2 For t h o s e d e p o s i t s t h a t do c o n t a i n c o e x i s t i n g p y r i t e and p y r r h o t i t e , the range o f s u l p h u r p r e s s u r e s i s l i m i t e d t o t h e e q u i l i b r i u m p r e s s u r e s of the p y r i t e - p y r r h o t i t e r e a c t i o n . A t 1+00°C, t h i s e q u i l i b r i u m p r e s s u r e i s 10"^ atmosphere; at 550°C. i t i s 10~^ atmosphere. -103-CHAPTER IV - GENESIS O r i g i n of i r o n compounds The i r o n of c o n t a c t metasomatic d e p o s i t s might have any one or a c o m b i n a t i o n of the f o l l o w i n g s o u r c e s : 1) F e r r i f e r o u s m e t e o r i c waters heated by an i n v a d i n g magma. 2) Bonanza l i m e s t o n e . 3) Vancouver group v o l c a n i c r o c k s . Ix) Nearby g r a n i t i c p l u t o n s . M e t e o r i c waters Under c e r t a i n c o n d i t i o n s groundwaters a re c a p a b l e of t r a n s p o r t i n g and d e p o s i t i n g i r o n compounds and s i l i c a . S hould such w a t e r s be he a t e d by an i n v a d i n g magma, the c o n t a i n e d i r o n and s i l i c a c o n c e i v a b l y c o u l d be f i x e d as m a g n e t i t e and s k a r n . However, as c o n t a c t metasomatic d e p o s i t s a re a s s o c i a t e d o n l y w i t h i n t r u s i o n s of i n t e r m e d i a t e c o m p o s i t i o n , and not h i g h l y a c i d i c or u l t r a b a s i c ones, such a mechanism does not seem v a l i d . Q u a t s i n o l i m e s t o n e I r o n might have been l e a c h e d i n some unknown way from the Q u a t s i n o l i m e s t o n e so p r e v a l e n t w i t h c o n t a c t metasomatic d e p o s i t s of t h e P a c i f i c -1014.-c o a s t . Inasmuch as such l i m e s t o n e has v e r y l i t t l e i r o n (0,06%; T a b l e I L L), p r o h i b i t i v e volumes of r o c k would be i n v o l v e d . Vancouver group v o l c a n i c r o c k s Most o f t h e d e p o s i t s of the P a c i f i c c o a s t r e p l a c e e i t h e r Karmutsen or Bonanza v o l c a n i c r o c k w h i c h may c o n t a i n up t o 6-8% Fe as an o r i g i n a l c o n s t i t u e n t . Such i r o n would be a source of i r o n f o r c o n t a c t metasomatic d e p o s i t s i f some mechanism o f " l a t e r a l s e c r e t i o n " c o u l d be invoked. B o y l e (1959) suggested l a t e r a l s e c r e t i o n of i r o n and s i l i c a from s u r r o u n d i n g metasediments took p l a c e d u r i n g metamorphism i n t h e Y e l l o w k n i f e a r e a , N.W.T. These e l e m e n t s , among o t h e r s , were then d e p o s i t e d as v e i n s i n d i l a t a n t zones. M i n e r a l i z a t i o n was shown t o be accompanied by widesprea d a l t e r a t i o n e x t e n d i n g outward from t h e m i n e r a l i z e d areas f o r many hundreds of f e e t . Hagner e t a l . (I963) con-c l u d e d t h a t m a g n e t i t e o f t h e S c o t t mine, N.Y. c o u l d have been d e r i v e d from a m p h i b o l i t e h o s t r o c k by metasomatism, r e g i o n a l metamorphism, and g r a n i t i z a t i o n . H i g h l y d i s p e r s e d f e r r i f e r o u s m a t e r i a l was c o n s i d e r e d by t h e authors t o have been r e l e a s e d from a m p h i b o l i t e and l a t e r c o n c e n t r a t e d i n t o o r e b o d i e s i n low p r e s s u r e zones. The w r i t e r b e l i e v e s t h a t the Karmutsen and/or Bonanza v o l c a n i c r o c k s a r e not t h e immediate sou r c e of i r o n i n c o n t a c t metasomatic d e p o s i t s f o r the f o l l o w i n g r e a s o n s : - 1 0 5 -1) These rocks have not been e x t e n s i v e l y metamorphosed, a l t e r e d , or g r a n i t i z e d . 2) There i s no evidence o f low p r e s s u r e zones such as d e s c r i b e d by Boyle and Hagner as f a v o u r a b l e s i t e s o f ore depos i t i on. 3) M a t e r i a l moving from the v o l c a n i c r o c k s t o form an orebody a d j a c e n t t o an i n t r u s i o n would be m i g r a t i n g a g a i n s t a r i s i n g t e m p e r a t u r e g r a d i e n t . F u r t h e r m o r e , i f the i n t r u s i o n were d i s c h a r g i n g w a t e r , carbon d i o x i d e , and o t h e r v o l a t i l e s from i t s m a r g i n s , m a t e r i a l m i g r a t i n g toward th e p l u t o n would be moving a l s o a g a i n s t a r i s i n g p r e s s u r e g r a d i e n t . LL) Barnes (1959) showed q u a l i t a t i v e l y t h a t i t i s i m p o s s i b l e f o r z i n c of the Hanover, N.M. c o n t a c t metasomatic base metal d e p o s i t s t o have been d e r i v e d from s u r r o u n d i n g sediments by l a t e r a l s e c r e t i o n . Nearby u n a l t e r e d Devonian s h a l e , c o n t a i n i n g s u f f i c i e n t z i n c t o c o n t r i b u t e s i g n i f i c a n t l y t o the m e t a l c o n t e n t o f t h e s e d e p o s i t s , has the same m e t a l c o n t e n t as i t s r e c r y s t a 1 1 i z e d and s i l i c i f i e d e q u i v a l e n t i n t h e c o n t a c t metamorphic a u r e o l e ( e x c l u d i n g s k a r n ) . Barnes' e v i d e n c e i n d i c a t e s t h a t m e t a l s do not m i g r a t e toward a c o n t a c t a u r e o l e . Nearby g r a n i t i c p l u t o n s Clapp (1913) suggested t h a t s e v e r a l s m a l l c o n t a c t m a g n e t i t e b o d i e s i n -106-s o u t h e r n Vancouver I s l a n d o r i g i n a t e d i n a d j a c e n t p l u t o n s as a m a g n e t i t e "magma". Magmatic m a g n e t i t e d e p o s i t s are known i n s e v e r a l l o c a l i t i e s . The i r o n ore of K i r u n a , Sweden, has a h i g h phosphorous content and a d i s t i n c t i v e t e x t u r e s u g g e s t -i n g a e u t e c t i c i n t e r g r o w t h of a p a t i t e and ma g n e t i t e ( L i n d g r e n , 1933,P'792). T i t a n i u m - r i c h m a g n e t i t e b o d i e s are common i n b a s i c and u l t r a b a s i c rocks of the G r e n v i l l e s u b - p r o v i n c e o f the Canadian S h i e l d . Pure m a g n e t i t e m e l t s a t 1600°C a l t h o u g h some r e d u c t i o n of m e l t i n g temperature c o u l d be c a u s e d by a s m a l l percentage o f v o l a t i l e s . Even a t s l i g h t l y reduced t e m p e r a t u r e s , however, m o l t e n m a g n e t i t e would c r y s t a l l i z e at much h i g h e r temperatures t h a n t h o s e c a l c u l a t e d from c o e x i s t i n g p y r i t e and p y r r h o t i t e (Table 1 0 ) . C o n s e q u e n t l y , m a g n e t i t e of c o n t a c t metasomatic d e p o s i t s does not appear t o have been d e p o s i t e d as a "magma". On the o t h e r hand, s e l e c t i v e replacement a l o n g f a v o u r a b l e h o r i z o n s , pseudomorphs of m a g n e t i t e a f t e r g a r n e t , g r a d a t i o n a l c o n t a c t s between s k a r n and u n a l t e r e d host r o c k s , and the abundance of h y d r o x y l - b e a r i n g m i n e r a l s such as e p i d o t e , s e r i c i t e , and c h l o r i t e suggest emplacement of magn e t i t e and s k a r n by h y d r o t h e r m a l f l u i d s emanating from a nearby g r a n i t i c p l u t o n . -107-M a r g i n s of s e v e r a l p l u t o n s i n c o n t a c t w i t h Karmutsen and Bonanza rocks are r e l a t i v e l y e n r i c h e d i n i r o n which c o u l d be c a r r i e d by o u t w a r d - m i g r a t i n g s o l u t i o n s and r e d e p o s i t e d as an orebody. H a m i l t o n et a l . (I96I4) have demonstrated e x p e r i m e n t a l l y t h a t i n a b a s a l t melt under a p a r t i a l p r e s s u r e of oxygen e q u a l t o t h a t c a l c u l a t e d f o r i n t r u s i o n s i n the p r e s e n t s t u d y , i r o n o x i d e c r y s t a l l i z e s at a lower temperature t h a n c o e x i s t i n g p l a g i o c l a s e and pyroxene. Thus, i r o n would be c o n c e n t r a t e d r e s i d u a l l y f o r l a t e r t r a n s p o r t i n a h y d r o t h e r m a l f l u i d . In a s e r i e s of e x p e r i m e n t s , O v c h i n n i k o v (1959) p r o v e d t h a t i r o n can be s e p a r a t e d from a s i l i c a t e m e l t which i s a s s i m i l a t i n g l i m e s t o n e . I t was found t h a t , by f u s i n g g r a n i t e or b a s a l t w i t h l i m e s t o n e and c o o l i n g the m e l t g r a d u a l l y , i r o n s e p a r a t e d from the s i l i c a t e m e l t and was t r a n s p o r t e d upwards. Depending on the p a r t i a l oxygen p r e s s u r e , m e t a l l i c i r o n , m a g n e t i t e , or h e m a t i t e was formed. O v c h i n n i k o v ' s experiments i l l u s t r a t e a p o s s i b l e mechanism whereby an i r o n -r i c h s e g r a g a t i o n might be c o n c e n t r a t e d i n t h e m a r g i n a l zone of a p l u t o n . A s i m p l e r a d i o a c t i v i t y s u r v e y was made by the author at the I r o n H i l l mine. A P r e c i s i o n R a d i a t i o n I n s t r u m e n t , I n c . S c i n t i l l o m e t e r , Model 111B was used. Readings were t a k e n - 1 0 8 -e v e r y 2 0 - 2 5 f e e t cn a l l l e v e l s of the open p i t . At each s t a t i o n the i n s t r u m e n t was p l a c e d on the bench face and t h e r a d i o a c t i v i t y r e a d i n mi 1 1iroentgens per hour. E l e v e n r e a d i n g s were taken on f r e s h g r a n o d i o r i t e , 19 on f r e s h a n d e s i t e , 21 on l i m e s t o n e , and 1+7 on o r e . I t was found t h a t g r a n o d i o r i t e gave the h i g e s t r e a d i n g s , ore gave i n t e r m e d i a t e , and l i m e s t o n e and a n d e s i t e gave the lowe s t r e a d i n g s . The range, i n mr/hr f o r each r o c k t y p e , and t h e average ( i n b r a c k e t s ) a re as f o l l o w s : g r a n o d i o r i t e 2 . 5 - 6 . 5 (1+.2), ore 1 . 0 - 6 . 0 ( 3 . 0 ) , a n d e s i t e 1 . 5 - 3 . 0 ( 2 . 1 ) , and l i m e s t o n e 1 . 0 - 3 . 0 ( 1 . 9 ) . As no c o n s i s t e n t d i f f e r e n c e c o u l d be d e t e c t e d I n r e a d i n g s t a k e n on massive m a g n e t i t e from t h o s e on massive garnet s k a r n , the two s e t s were combined.. N e i t h e r was t h e r e a d e t e c t a b l e d i f f e r e n c e i n ore formed by replacement o f a n d e s i t e from t h a t r e p l a c i n g l i m e s t o n e . The i n t e r m e d i a t e r e a d i n g s found i n ore might be i n t e r p r e t e d as evidence t h a t r a d i o a c t i v e t r a c e r elements accompanied i r o n and s i l i c a i n h y d r o t h e r m a l emanations from the Quinsam i n t r u s i o n . The P r e s c o t t and Paxton mines, i n p a r t i c u l a r , have a c r u d e c o n c e n t r i c z o n i n g around a c e n t r a l ore zone (Maps 2 and I I). These c e n t r e s a r e on the c o u n t r y r o c k s i d e o f the i n t r u s i v e c o n t a c t and t h e p l u t o n i t s e l f a c t u a l l y l i e s w i t h i n p e r i p h e r a l zones. Such z o n i n g i s e x p r e s s e d by a s e r i e s o f c o n c e n t r i c c i r c l e s about a c e n t r e s l i g h t l y removed from t h e -109-g r a n i t i c c o n t a c t . T h i s arrangement s u g g e s t s . t h a t the / m i n e r a l i z i n g s o l u t i o n s d i d not m i g r a t e " h o r i z o n t a l l y " t o the ore zone from the a d j a c e n t p l u t o n . b u t r a t h e r a l o n g t h e i n t r u s i v e c o n t a c t . When a f a v o u r a b l e o r e - f o r m i n g environment was reached, d e p o s i t i o n took p l a c e i n t h e Vancouver group hos t rocks and z o n i n g developed around the s i t e o f i n i t i a l d e p o s i t i o n . A n a l y z e d specimens, of the Coast Copper s t o c k a d j a c e n t t o the M e r r y Widow d e p o s i t show no s t a t i s t i c a l change i n i r o n c o n t e n t from the i n t e r i o r of the i n t r u s i o n toward i t s ' ; m argin ( F i g . 5 and 6 ) . T h i s evidence a l s o s u p p o r t s the t h e o r y t h a t i r o n d i d not m i g r a t e h o r i z o n t a l l y from the i n t r u s i o n . The w r i t e r c o n c l u d e s t h a t the immediate so u r c e of i r o n i n c o n t a c t metasomatic m a g n e t i t e d e p o s i t s i s a nearby i n t r u s i o n . However, the u I t i m a t e s o u r c e i s v e r y p r o b a b l y the Karmutsen v o l c a n i c r o c k s . G r a n i t i c p l u t o n s , i n t r u d i n g and i n p a r t a s s i m i l a t i n g Karmutsen r o c k s , t h e r e b y a c q u i r e d a d d i t i o n a l i r o n i n t h e i r margins. T h i s i r o n s u b s e q u e n t l y was f i x e d as m a g n e t i t e d e p o s i t s i n and near Q u a t s i n o l i m e s t o n e . C o m p o s i t i o n o f t h e o r e - f o r m i n g f l u i d s Statements r e g a r d i n g c o m p o s i t i o n o f ore f l u i d s must be o f a q u a l i t a t i v e , o r a t best s e m i - q u a n t i t a t i v e , n a t u r e - l i b -a l i m i t a t i o n imposed by our l a c k o f knowledge of i m p o r t a n t v a r i a b l e s which determine c o m p o s i t i o n of such f l u i d s . M i n e r a l assemblages i n c o n t a c t metasomatic d e p o s i t s are a r e s u l t o f i n t e r a c t i o n o f s e v e r a l v a r i a b l e s i n a medium w h i c h i s v e r y l i k e l y above i t s c r i t i c a l p o i n t . The r e l a t i o n between com-p o s i t i o n of ore m i n e r a l s and ore s o l u t i o n s i s complex. At l e a s t f o u r independent v a r i a b l e s ( p r e s s u r e , t e m p e r a t u r e , i o n i c s p e c i e s , and a c t i v i t y c o e f f i c i e n t s ) must be q u a l i t a t i v e l y e v a l u a t e d i n o r d e r t o deduce the c o m p o s i t i o n o f an ore s o l u t i o n from the c o m p o s i t i o n of p r e c i p i t a t e d m i n e r a l s . Even i f t h e s e v a r i a b l e s were known, however, a p p l i c a t i o n of e m p i r i c a l f u n c t i o n s i s l i m i t e d t o t h e cases i n which e q u i l i b r i u m d u r i n g p r e c i p i t a t i o n and absence of p o s t - d e p o s i t i o n a l changes can be demonstrated (Barnes and K u l l e r u d , 1 9 5 7 a ) . Under c e r t a i n c o n d i t i o n s the d i s t r i b u t i o n o f minor elements i n v e i n m i n e r a l s c o u l d be used to d e f i n e the t e m p e r a t u r e , p r e s s u r e , and c h e m i c a l c o m p o s i t i o n of t h e f l u i d from w h i c h p r e c i p i t a t i o n took p l a c e Hoi l and, 1 9 5 6 ) . Because many of t h e v a r i a b l e s mentioned above are unknown i n t h e d e p o s i t s s t u d i e d , the f o l l o w i n g d i s c u s s i o n w i l l be l i m i t e d t o an o u t l i n e o f the most p r o b a b l e c o m p o s i t i o n and p h y s i c a l n a t u r e o f t h e f l u i d w hich t r a n s p o r t e d i r o n and d e p o s i t e d m a g n e t i t e i n c o n t a c t metasomatic d e p o s i t s . — 111-I f a magma has been i n p l a c e long enough t o r e a c h d i f f u s i o n e q u i l i b r i u m , the p a r t i a l p r e s s u r e of water w i l l be the same throughout the m e l t . Kennedy (1955) c o n c l u d e d t h a t t h i s c o u l d be t r u e o n l y i f t h e a c t u a l q u a n t i t y of water i s g r e a t e r i n c o o l e r p a r t s of the melt and i n t h o s e p a r t s h a v i n g the lowest c o n f i n i n g p r e s s u r e . These c o n d i t i o n s would e x i s t i n margins or upper p a r t s of the magma chamber i . e . the cupolas and apophyses o f a p l u t o n . As water m i g r a t e s toward the margins of a magma chamber, i t w i l l be accompanied by o t h e r v o l a t i l e m a t e r i a l . Osborne (1959) has shown t h a t rocks of the c a l c -a l k a l i t r e n d , such as t h o s e of p l u t o n s a d j a c e n t t o the d e p o s i t s s t u d i e d , a r e produced by f r a c t i o n a l c r y s t a l l i z a t i o n at c o n s t a n t p a r t i a l oxygen p r e s s u r e . Osborne - s t a t e s t h a t as water d i s s o c i a t e s i n the m e l t , t h e p a r t i a l oxygen p r e s s u r e w i l l e i t h e r remain c o n s t a n t or i n c r e a s e s l i g h t l y . The p a r t i a l 0 2 p r e s s u r e f o r m e l t s of two c o m p o s i t i o n s has been c a l c u l a t e d as 21.14. x 12 1 ? 10" atmosphere and 14-1.9 x 10 atmosphere (p.99); hence, p l u t o n s a d j a c e n t to mag n e t i t e d e p o s i t s o f t h i s s t u d y c r y s t a l -l i z e d under almost i d e n t i c a l oxygen p r e s s u r e s and, a c c o r d i n g t o Osborne, t h i s i s p o s s i b l e i n t h e presence o f abundant water. At 1100°C the s o l u b i l i t y of water i n b a s a l t at 2000 bars" i s I4..6 weight p e r c e n t ; i n a n d e s i t e at the same P , T - c o n d i t i o n s the s o l u b i l i t y i s 6 .0 weight p e r c e n t ( H a m i l t o n et a l . ,19614.). There i s a s m a l l but im p o r t a n t v a r i a t i o n i n s o l u b i l i t y w i t h - 1 1 2 -temperature the i n c r e a s e i n s o l u b i l i t y at c o n s t a n t p r e s s u r e amounts to r o u g h l y 0 . 5 weight p e r c e n t f o r each 100°C d e c l i n e i n temperature (Kennedy, 1955.P«1|-91) . A n d e s i t e a t 800°C t h e r e f o r e would c o n t a i n 7»5 weight p e r c e n t water., I t i s apparent from t h e s e f i g u r e s t h a t abundant water i s a v a i l a b l e i n the p l u t o n s a s s o c i a t e d w i t h m a g n e t i t e d e p o s i t s and t h a t such w a t e r , m i g r a t i n g toward the m a r g i n s , c o u l d t r a n s p o r t and l a t e r d e p o s i t m e t a l compounds as p e r i p h e r a l o r e b o d i e s . As the c r i t i c a l temperature. o f water i s 37l4-°C at a p r e s s u r e o f 220 atmospheres, pure water would be i n the s u p e r c r i t i c a l s t a t e a t the P , T - c o n d i t i o n s e s t i m a t e d f o r ore f o r m a t i o n . O r e - f o r m i n g f l u i d s , however, would be a complex s o l u t i o n c o n t a i n i n g many s o l u t e s and s o l v e n t s , each of w h i c h would a f f e c t t h e P-V-T r e l a t i o n s of the system. D u r i n g c o n t a c t metasomatism near l i m e s t o n e , f o r example, CO2 would be a dominant c o n s t i t u e n t and i t s p r i n c i p a l e f f e c t would be t o lower the c r i t i c a l t e m p e r a t u r e o f w a t e r . On t h e other hand, s o l u t i o n s o f m e t a l c h l o r i d e s (the p r i n c i p a l compounds found as f l u i d i n c l u s i o n s i n v e i n m i n e r a l s ) would r a i s e t h e c r i t i c a l p o i n t of such s o l u t i o n s above t h a t o f pure w a t e r . Because s a l i n i t y and C O 2 / H 2 O r a t i o s v a r y i n an unknown manner, i t can o n l y be assumed t h a t the P-V-T r e l a t i o n s o f aqueous o r e - f o r m -o ing f l u i d s a r e s i m i l a r to those of pure w a t e r . At 850 C and - 1 1 3 -2000 bars p r e s s u r e ( the P , T - c o n d i t i o n s d u r i n g i n t r u s i o n ) the d e n s i t y of an aqueous ore f l u i d would be l e s s than h a l f t h a t of water under s t a n d a r d c o n d i t i o n s (Smith, 1 9 6 3,p.8 0 ) . F i e l d o b s e r v a t i o n s o f c o n t a c t d e p o s i t s i n l i m e s t o n e show t h a t l a r g e volumes o f CaCO^ have been r e p l a c e d by m a g n e t i t e and s k a r n . Because thermal d i s s o c i a t i o n o f c a l c i t e i s u n l i k e -l y under the c o n d i t i o n s of i n t r u s i o n , removal of carbonate must have been e f f e c t e d by s o l u t i o n . T h i s would be p o s s i b l e o n l y i f t h e pH of the o r e - b e a r i n g s o l u t i o n s was l e s s t h a n 7 . 8 ( t h e minimum s t a b i l i t y pH of c a l c i t e ) . I t may p o s s i b l y have been below 7 as the s o l u b i l i t y of c a l c i t e i n pure water a t 500°C and 1000 bars i s o n l y 120 ppm (Morey, 1 9 5 7). E v i d e n c e s u p p o r t i n g a c i d i c o r e f l u i d s i s t h e presence o f s e r i c i t i c a l t e r a t i o n o f p l u t o n s a d j a c e n t t o d e p o s i t s . At temperatures above 350°C, s e r i c i t e i s s t a b l e o n l y i n an a c i d environment (Stringham, 1 9 5 2 ). A s m a l l s e r i c i t e s t a b i l i t y f i e l d at lower temperature and s l i g h t l y a l k a l i n e c o n d i t i o n s might i n d i c a t e t h a t s e r i c i t e i n the p l u t o n s d i d not form .at the time o f ore d e p o s i t i o n but r a t h e r d u r i n g a l a t e r p e r i o d at lower temper-a t u r e and h i g h e r pH. Such c o n d i t i o n s a re u n l i k e l y , however, because z e o l i t e , which occurs- as p o s t - s e r i c i t e v e i n s i n s e v e r a l p l u t o n s (such as near the K l a a n c h , I r o n H i l l ( P l a t e I ) , and F.L. d e p o s i t s ) , i s s t a b l e o n l y below 350-i4-00°C — 111+— (Stringham, 1 9 5 2 ). Assuming temperature d e c l i n e d as m i n e r a l d e p o s i t i o n p r o g r e s s e d , s e r i c i t e must have been d e p o s i t e d above 1+00°C from a c i d i c s o l u t i o n s . At 25°C the pH of pure water i s 7 . 0 . Under p r e s s u r e , however, the pH of a n e u t r a l s o l u t i o n i s s l i g h t l y l e s s than 7 and i f i t c o n t a i n s a d i s s o l v e d s a l t i t s n e u t r a l p o i n t i s s l i g h t l y g r e a t e r t h a n 7 (Barton, 1 9 5 9 ). The e f f e c t s on pH of p r e s s u r e and s a l t are s m a l l , however, when compared t o t h a t o f t e m p e r a t u r e . With i n c r e a s i n g t e m p e r a t u r e , t h e pH of n e u t r a l i t y decreases s t e a d i l y t o a minimum of 5 . 6 a t 250°C. At the c r i t i c a l temperature o f water, t h e pH o f n e u t r a l i t y has r i s e n t o about 7 . 0 . In the s u p e r c r i t i c a l s t a t e the e f f e c t of t e m p e r a t u r e on pH i s much g r e a t e r and, a t 500°C and 2000 b a r s , the pH of n e u t r a l i t y i s c l o s e t o 5 . 0 (Barnes and K u l l e r u d , 1 9 6 1 ) . I t i s d i f f i c u l t t o p r e d i c t the e f f e c t o f temperature on t h e pH of complex s o l u t i o n s such as ore f l u i d s but i t i s assumed t h e i r pH approaches t h a t of water under s i m i l a r P , T - c o n d i t i o n s . S e v e r a l l i n e s o f e v i d e n c e i n d i c a t e t h a t i r o n was c a r r i e d as c h l o r i d e . S u r f a c e i n c r u s t a t i o n s at most h i g h -temperature vents i n t h e Katmai area c o n t a i n abundant m a g n e t i t e as w e l l as c h l o r i d e s and f l u o r i d e s . A l t h o u g h Z e i s (1929) c o n c l u d e d t h a t f u m a r o l i c m a g n e t i t e and h e m a t i t e formed f r o m i r o n h a l i d e vapour, s i m p l e v o l a t i l i t y of i r o n c h l o r i d e s - l 15-cannot c o n t r i b u t e s u b s t a n t i a l amounts of i r o n t o d i l u t e ore s o l u t i o n s ( K r a u s k o p f , I96I4.). At 500°C f e r r i c c h l o r i d e i s a l i q u i d w i t h a vapour p r e s s u r e o f o n l y 9 . 7 b a r s . The vapour i s composed of 98% F e 0 C l , gas and 2% F e C l _ gas ( H o l s e r and d b j> Schneer, I 9 6 l , p , 3 7 8 ) . At t h i s temperature a s m a l l amount of f e r r i c c h l o r i d e d i s s o c i a t e s t o c r y s t a l l i n e F e C l ^ and gaseous C l ^ . The vapour p r e s s u r e of F e C l ^ at 500°C i s l e s s t h a n 10"^ bar ( H o l s e r and Schneer,1961,p.3 7 8 ). A l t h o u g h F e ^ C l ^ i s the most v o l a t i l e of the i r o n c h l o r i d e s , i t s c o n c e n t r a t i o n i n the vapour phase i s r e s t r i c t e d by the p r e s e n c e of water w i t h w h i c h i t r e a c t s to form f e r r i c o x i d e and hydrogen c h l o r i d e , H o l s e r and Schneer c a l c u l a t e d t h a t , a t 500°C and 500 b a r s , t h e c o n c e n t r a t i o n i f HC1 n e c e s s a r y to m o b i l i z e 1 ppm Fe as F e ^ C l ^ i s 2 . 7 N . C o n c e n t r a t i o n s of HC1 i n v o l c a n i c emanations, are commonly of the o r d e r 0 . 0 1 - 0 . I N and K r a u s k o p f (1957 ,p.793) e s t i m a t e d 0.06N HC1 f o r magmatic vapour at 600°C. C o n s e q u e n t l y , the h i g h c o n c e n t r a t i o n s o f HC1 n e c e s s a r y to m o b o l i z e F e ^ C l ^ gas are u n l i k e l y i n n a t u r a l f l u i d s . P r o b a b l y s o l u b i l i t y of i r o n c h l o r i d e s i n an o r e - f o r m i n g f l u i d i s more i m p o r t a n t than v o l a t i l i t y because the d e n s i t y of such f l u i d s , under the P , T - c o n d i t i o n s of ore f o r m a t i o n , would be about 0 . 8 and c o n s e q u e n t l y are more l i q u i d - l i k e than g a s - l i k e . At 100°C the s o l u b i l i t y of F e ^ l ^ i s 5350 g / l i t r e of w a t e r and of F e C l 0 i s 1050 g / l i t r e of w a t e r . In comparison, NaCl at the -116-same c o n d i t i o n s has a s o l u b i l i t y of 390 g/1 (Hodgman, 19.58). In a t h e o r e t i c a l and e x p e r i m e n t a l study of the s o l u b i l i t y of ma g n e t i t e i n d i l u t e aqueous s o l u t i o n s o f KC1 at h i g h temper-a t u r e and p r e s s u r e , H o l s e r and Schneer (1961) co n c l u d e d t h a t i r o n m o b i l i z e d i n t h e i r e xperiments was i n t r u e s o l u t i o n and t h a t v o l a t i l i t y of i r o n h a l i d e s d i d not a c c o u n t f o r any s i g n i -f i c a n t m o b i l i z a t i o n of i r o n . In a d d i t i o n t o s i m p l e c h l o r i d e s , I r o n can be c a r r i e d as complex i o n s . For example, sodium, a common c o n s t i t u e n t of f l u i d i n c l u s i o n s i n ore m i n e r a l s (Smith, 1951+5 Roedder, Ingram, and H a l l , 1963) forms complexes such as Na(FeCl^) or N a 2 ( F e C l ^ ) ( K a l n i n , 1 9 6 2 ) . When an ore f l u i d reaches a s i t e of d e p o s i t i o n i t s c h e m i c a l and p h y s i c a l n a t u r e changes. The temperature of t h i s s u p e r c r i t i c a l f l u i d has decreased from 800-900°C t o about i4-00-550°C (T a b l e 10) and i t s d e n s i t y has i n c r e a s e d t o about 0 . 8 . I n t h i s t e m p e r a t u r e and d e n s i t y range, most of t h e i r o n c h l o r i d e i s c a r r i e d i n t r u e s o l u t i o n and some f e r r i c c h l o r i d e d i s s o c i a t e s t o f e r r o u s c h l o r i d e and c h l o r i n e . C o n s e q u e n t l y , s o l u t i o n s r e a c h i n g a s i t e of ore f o r m a t i o n c o n t a i n both f e r r o u s and f e r r i c c h l o r i d e . Z e i s (1929) suggested t h e f o r m a t i o n o f m a g n e t i t e i n the Katmai area was brought about by the r e a c t i o n : -117-F e 2 C l ^ + F e C l 2 + i4-H20 (1) For t h e complex i o n s , t h e f o l l o w i n g r e a c t i o n has been suggested ( K a l n i n , 1 9 6 2 ) : a gas, t h e r e b y p e r m i t t i n g r e a c t i o n (1) t o proceed t o the r i g h t w i t h d e p o s i t i o n of m a g n e t i t e . In c o n t a c t metasomatic d e p o s i t s near l i m e s t o n e t h e HC1 would be n e u t r a l i z e d by c a l c i t e , p e r -m i t t i n g p r e c i p i t a t i o n of m a g n e t i t e . and c a l c i t e a t 100 C and a t m o s p h e r i c p r e s s u r e (Kuhara, 192.5) and a t h i g h temperatures and low p r e s s u r e s (Vinogradov and Dontsova, 1 9 5 2 ). Only r e c e n t l y have q u a l i t a t i v e e x p e r i m e n t s c o n f i r m e d t h a t m a g n e t i t e can be d e p o s i t e d by n e u t r a l i z a t i o n of i r o n c h l o r i d e s o l u t i o n s a t g e o l o g i c a l l y s i g n i f i c a n t t e m p e r a t u r e s and p r e s s u r e s . H o l s e r and Schneer (1961) p r e -pared i r o n c h l o r i d e s o l u t i o n s of 1000 ppm f e r r i c i r o n and 500 ppm f e r r o u s i r o n w i t h a pH o f about 2 . T h i s s o l u t i o n was a l l o w e d to r e a c t both w i t h crushed l i m e s t o n e and a c a l c i t e c l e a v a g e rhomb at 320°C and 1100 b a r s . In both cases the pr o d u c t was c r y s t a l l i n e m a g n e t i t e . , A f t e r r e a c t i o n s were Fe.O, In t h e Katmai f u m a r o l e s , HC1 would be swept away as M a g n e t i t e has been s y n t h e s i z e d from f e r r o u s c h l o r i d e - 1 1 8 -completed the s o l u t i o n s c o n t a i n e d l e s s than 20 ppm Fe'^ and +2 l e s s than 200 ppm Fe and had a pH s l i g h t l y g r e a t e r than 5 ( H o l s e r and Schneer, 1 9 6 1,p.3 7 6 ) . In the absence o f a s t r o n g a c i d , i t i s u n l i k e l y t h a t much s o l u t i o n of c a l c i t e would t a k e p l a c e . In carbon d i o x i d e s o l u t i o n s , t h e s o l u b i l i t y of c a l c i t e decreases s t e a d i l y w i t h i n c r e a s i n g t e m p e r a t u r e . At about 371L°C the s o l u b i l i t y i s l e s s - 5 t h a n 10 m f o r p a r t i a l p r e s s u r e s of C C ^ of 1-100 atmospheres. The s o l u b i l i t y might i n c r e a s e s l i g h t l y above LL00°C but e x p e r i m e n t a l e v i d e n c e i s i n c o n c l u s i v e ( E l l i s , 1 9 5 9 ) . The s o l u b i l i t y of CC>2 i n water i s c o n s i d e r a b l e about 20 weight p e r c e n t at l i00°C and 2300 bars ( S m i t h , 1 9 6 3,p . 3 3 0 ) . Carbon d i o x i d e i n excess o f t h a t d i s s o l v e d i n an o r e - f o r m i n g f l u i d would e x i s t as gaseous C O 2 . Because of the l a c k of C C ^ - b e a r i n g m i n e r a l s i n the d e p o s i t s , the p a r t i a l p r e s s u r e of C 0 2 can o n l y be e s t i m a t e d w i t h i n wide l i m i t s . The e q u i l i b r i u m p r e s s u r e a t 885°C ( t h e approximate temperature of i n t r u s i o n ) f o r the r e a c t i o n CaCO-^== CaO + CO2 i s one atmosphere ( B i r c h , 191+25 Weeks, 1 9 5 6 ) . At 500°C, c a l c i t e i s s t a b l e t o a t l e a s t a -3 p a r t i a l C 0 2 p r e s s u r e o f 10 atmosphere (Hoi l a n d , 1 9 5 9 , p . 2 l 8 ) . D u r i n g ore f o r m a t i o n , however, s o l u t i o n of l i m e s t o n e by o r e -f o r m i n g f l u i d s would r e l e a s e CO2 and i n c r e a s e the p a r t i a l p r e s s u r e o f c a r b o n d i o x i d e . An upper l i m i t t o t h e p o s s i b l e CO2 p r e s s u r e d u r i n g ore d e p o s i t i o n can be e s t i m a t e d by the - 1 1 9 -absence o f s i d e r i t e i n metasomatic m a g n e t i t e d e p o s i t s . T h i s m i n e r a l i s r e l a t i v e l y u n s t a b l e at e l e v a t e d temperatures and at 327°C, the h i g h e s t t e m p e r a t u r e f o r which thermodynamic data-are a v a i l a b l e , s l i g h t l y more than 100 atmospheres COg p r e s s u r e are n e c e s s a r y t o en t e r t h e s i d e r i t e s t a b i l i t y f i e l d ( H o l l a n d , 1 9 5 9 ,p. 1 9 9 ) . At £00°C the n e c e s s a r y C 0 2 p r e s s u r e c o u l d w e l l be over 1000 atmospheres. C o n s e q u e n t l y , t h e absence o f s i d e r i t e i n t h e s e r e l a t i v e l y h i g h temperature d e p o s i t s may be a t t r i b u t e d t o a p a r t i a l p r e s s u r e o f C O ^ l e s s than about 1000 atmospheres. The supposed o x i d a t i o n o f m a g n e t i t e by CO2 ( B u t l e r , 1923) has been shown t o be e x t r e m e l y u n l i k e l y between 200-500°C (Hawley and Robins on, I9I4.8). Between t h e s e t e m p e r a t u r e s the r a t i o CO:CC>2 at e q u i l i b r i u m i n the r e a c t i o n 2Fe^O^ + CC^^ 'b 12 7 3 F e 2 0 3 + CO ranges from about 1:10 t o 1:10 . Hawley and Robinson c o n s i d e r t h e s e r a t i o s v e r y u n l i k e l y i n c o n t a c t d e p o s i t s . The absence o f n a t i v e i r o n i n ma g n e t i t e d e p o s i t s on the o t h e r hand, p l a c e s the upper l i m i t of t h e C O : C 0 2 r a t i o a t about 2 : 3 (Lasky, 1 9 3 1 ) . F l u i d s i n e q u i l i b r i u m w i t h c r y s t a l l i n e m a g n e t i t e would be.' : p r o b a b l y n e a r l y n e u t r a l or s l i g h t l y a l k a l i n e s u p e r -c r i t i c a l aqueous s o l u t i o n s . S u p e r c r i t i c a l c arbon d i o x i d e would be p r e s e n t but m a i n l y as a m i x t u r e r a t h e r t h a n i n t r u e -120-s o l u t i o n ( Smith, I 9 6 3 ,p.8l)• For t h e assemblage m a g n e t i t e , p y r i t e , p y r r h o t i t e , p l u s vapour between 5>00-55>0°C, the e q u i l i b r i u m p a r t i a l p r e s s u r e of oxygen i s 10""1® to 10~^ atmosphere and of s u l p h u r i s 10"^ t o 10 _3 atmosphere (Chap. I I I ) . The p a r t i a l p r e s s u r e o f ot h e r v o l a t i l e s i n t h e vapour phase i s unknown but Barnes and K u l l e r u d (1961) have c a l c u l a t e d t h a t , f o r the c o n d i t i o n s s t a t e d above, the vapour p r e s s u r e of a m i x t u r e of S„, S. , S., S D , SO_, and 0_ i s between 10"^ and 2 14. 6 o 3 2 1 ft 10~l atmosphere. As t h e p a r t i a l p r e s s u r e of S^ alo n e i s 10 to 10"^ atmosphere, d i v a l e n t s u l p h u r i s f a r more abundant than o t h e r s p e c i e s of s u l p h u r . The f o r e g o i n g d i s c u s s i o n i n d i c a t e s t h a t great changes i n t h e p h y s i c a l and c h e m i c a l n a t u r e o f an o r e - f o r m i n g f l u i d must t a k e p l a c e d u r i n g the process o f ore d e p o s i t i o n . W h i l e s t i l l i n the magma chamber, t h e f l u i d was a t a temperature about 800-900°C w i t h a p a r t i a l oxygen p r e s s u r e of about 10 atmosphere. T o t a l p r e s s u r e on the system was about 2000 bars and, because w a t e r i s assumed t o be the major v o l a t i l e a t t h i s s t a g e , t h i s would a p p r o x i m a t e t h e p a r t i a l p r e s s u r e of HgO. As i t l e f t t h e magma t h e f l u i d had a d e n s i t y o f about O.I4., a pH l e s s t h a n 7.8, and c a r r i e d s u b s t a n t i a l amounts o f i r o n and l e s s e r amounts o f s i l i c a , magnesium, and aluminum n e c e s s a r y t o form s k a r n i n l i m e s t o n e . Where s k a r n i f i c a t i o n t o o k p l a c e 1 -121-i n v o l c a n i c r o c k s , these h o s t rocks no doubt c o n t r i b u t e d such elements t o t h e f l u i d system. At a l a t e r s t a g e , t h e temperature o f the ore f l u i d s d e c l i n e d t o about !+00-5E>0°C. The s i l i c a c o n t e n t decreased r e l a t i v e to i r o n ; the p a r t i a l oxygen p r e s s u r e d e c r e a s e d t o w i t h i n l i m i t s o f 1 0 " ^ t o 1 0 " ^ atmosphere; and m a g n e t i t e was p r e c i p i t a t e d as a s t a b l e phase r e p l a c i n g l i m e s t o n e and v o l c a n i c rocks as w e l l as e a r l i e r s k a r n . In the f i n a l s t a g e of s u l p h i d e d e p o s i t i o n , t h e p a r t i a l -8 ^ p r e s s u r e o f s u l p h u r i n c r e a s e d t o 10" t o lO"- 3 atmosphere, a l l o w i n g i r o n and c o p p e r - i r o n s u l p h i d e s to form. The p a r t i a l 18 p r e s s u r e o f oxygen had dropped t o a minimum range of 10" -27 to 10 atmosphere. The pH o f the f l u i d had now become n e a r l y n e u t r a l m a i n l y by r e a c t i o n w i t h l i m e s t o n e . Removal o f S i , A l , K, Na, Ca, COg, C ^ , e t c . was f a c i l i t a t e d by an i n c r e a s e o f f l u i d d e n s i t y t o about 0 . 8 . Ore C o n t r o l s R e c o g n i z e d ore c o n t r o l s of c o n t a c t metasomatic m a g n e t i t e d e p o s i t s can be d i v i d e d i n t o two main t y p e s : 1) p h y s i c a l ore c o n t r o l s and 2) c h e m i c a l o r e / c o n t r o l s . Some have both p h y s i c a l and c h e m i c a l c h a r a c t e r i s t i c s and may be -122-r e g a r d e d as p h y s i c o - c h e m i c a l c o n t r o l s . P h y s i c a l ore c o n t r o l s No c o n t a c t metasomatic i r o n o re d e p o s i t s o c c u r i n the Upper P a l e o z o i c l i m e s t o n e and v o l c a n i c rocks o f Vancouver and Texada I s l a n d s . Perhaps t h i s i s m e r e l y because t h e exposed area of such rocks i s much l e s s than the exposed area of Upper T r i a s s i c r o c k s (50 sq. mi. o f U. P a l e o z o i c v s . 600 sq . m i . of Vancouver group; Canada, G e o l . S u r v e y Map 932A,1962; Mathews and McCammon,1957,Fig.3)• On the o t h e r hand, some c h e m i c a l f a c t o r may favour d e p o s i t i o n of c o n t a c t metasomatic i r o n ore d e p o s i t s i n Upper T r i a s s i c r o c k s . One p o s s i b l e c h e m i c a l f a c t o r i s d i s c u s s e d i n t h e s e c t i o n "Chemical o re c o n t r o l s " below. A l l m a g n e t i t e o r e b o d i e s s t u d i e d a r e found i n f o l d e d r o c k s , e i t h e r on a r e g i o n a l or l o c a l s c a l e . Broad, open f o l d s are c h a r a c t e r i s t i c of T r i a s s i c r o c k s on Vancouver I s l a n d . Superimposed on t h e s e a r e s m a l l , g e n e r a l l y c l o s e d , l o c a l f o l d s w h ich i n c r e a s e i n i n t e n s i t y toward p l u t o n s and a r e p r o b a b l y the r e s u l t o f f o r c e f u l i n t r u s i o n . Of the 12 d e p o s i t s s t u d i e d , 10 a r e i n s y n c l i n e s and t h e ot h e r two may be i n a n t i c l i n e s . D u r i n g f o l d i n g o f t h e Vancouver group, v o l c a n i c r o c k s which were l o c a l l y b r e c c i a t e d p r o v i d e d more open space f o r i n g r e s s -123-o f o r e - f o r m i n g f l u i d s . S h a t t e r i n g o f these v o l c a n i c rocks i s a l s o a p h y s i c o - c h e m i c a l c o n t r o l whereby repl a c e m e n t of .such r o c k s was enhanced by i n c r e a s e d s u r f a c e a r e a . L i m e s t o n e , on the o t h e r hand, f l o w e d d u r i n g f o l d i n g and remained impermeable to o r e - f o r m i n g f l u i d s . Both s t r a t i g r a p h i c and igneous c o n t a c t s a r e other i m p o r t a n t o r e c o n t r o l s . I n the' P a x t o n d e p o s i t , f o r example, the best o re i s a l o n a the c o n t a c t of G i l l i e s i n t r u s i o n and \ c o u n t r y r o c k s . From t h i s c o n t a c t s k a r n and m a g n e t i t e extend a l o n g the c o n t a c t of M a r b l e Bay l i m e s t o n e and Texada group a n d e s i t e . The J e s s i e and Merry Widow d e p o s i t s are t a b u l a r and p a r a l l e l t o an i n t r u s i v e c o n t a c t . For t h o s e d e p o s i t s which are not d i r e c t l y i n c o n t a c t w i t h an i n t r u s i o n , p r e - o r e f a u l t s were p r o b a b l y channelways a l o n g which m i n e r a l i z i n g f l u i d s t r a v e l l e d t o s i t e s of d e p o s i t i o n . The K i n g f i s h e r o r e b o d i e s , f o r example, a r e at the i n t e r s e c t i o n of a s t e e p l y - d i p p i n g normal f a u l t and a g e n t l y - d i p p i n g t h r u s t f a u l t . There i s some evidence t h a t the Y e l l o w K i d and Tassoo o r e b o d i e s a l s o were c o n t r o l l e d , at l e a s t i n p a r t , by p r e - o r e f a u l t s . The l o c a l c o n f i g u r a t i o n of a c o n t a c t between c o u n t r y r o c k and p l u t o n i s an i m p o r t a n t c o n t r o l ; i r r e g u l a r tongues or cu p o l a s of i n t r u s i o n p r o j e c t i n g i n t o c o u n t r y r o c k s are f a v o u r --121+-a b l e s i t e s of ore d e p o s i t i o n . At the K l a a n c h d e p o s i t , a c u p o l a of q u a r t z monzonite p r o j e c t s westward i n t o l i m e s t o n e and a n d e s i t e and m a g n e t i t e has r e p l a c e d t h e s e rocks near the nose of the p r o j e c t i o n . Vancouver group rocks p a r t l y s u r r o u n d e d by g r a n i t i c i n t r u s i o n s are f a v o u r a b l e s i t e s o f o r e d e p o s i t i o n a t t h e F.L., I r o n H i l l , and Brynnor mines. A l t h o u g h a l l c o n t a c t metasomatic d e p o s i t s are r e l a t e d t o igneous c o n t a c t s , t h e y may range up to s e v e r a l hundred f e e t d i s t a n t from t h e a c t u a l exposed c o n t a c t ( i . e . Tassoo, Coast Copper, K i n g f i s h e r , Lake, and Brynnor d e p o s i t s ) . Other c o n t r o l s are r e q u i r e d t o l o c a l i z e ore d e p o s i t s . S e l e c t i v e r eplacement of f a v o u r a b l e r o c k u n i t s i s a r e l a t i v e l y minor ore c o n t r o l i n the m a j o r i t y o f the d e p o s i t s s t u d i e d . A l l t h r e e u n i t s of t h e Vancouver group are them-s e l v e s r e l a t i v e l y homogeneous and l a c k I n d i v i d u a l beds f a v o u r a b l e to s e l e c t i v e r e p l a c e m e n t . A l a r g e p a r t of the Coast Copper orebody has r e p l a c e d what i s thought t o be a narrow l i m e s t o n e bed i n o t h e r w i s e massive v o l c a n i c r o c k (Eastwood and M e r r e t t , 1 9 6 1 ) . As t h e r e i s no c o n c l u s i v e e v i d e n c e o f l i m e s t o n e i n the mine, o r e c o n c e i v a b l y c o u l d have r e p l a c e d a v o l c a n i c bed which p o s s e s s e d f a v o u r a b l e p h y s i c a l or c h e m i c a l p r o p e r t i e s . The J e s s i e and Tassoo d e p o s i t s w h i c h a r e r o u g h l y c onformable t a b u l a r b o d i e s i n v o l c a n i c rocks may -125-be s e l e c t i v e r e p l a c e m e n t s of former u n i t s of unknown c o m p o s i t i o n . C h e m i c a l ore c o n t r o l s The p resence o f l i m e s t o n e i s t h e most i m p o r t a n t c h e m i c a l f a c t o r o f d e p o s i t i o n of m a g n e t i t e i n c o n t a c t meta-so m a t i c d e p o s i t s . I t i s a n e c e s s a r y c o n s t i t u e n t f o r two r e a s o n s : 1) the s e p a r a t i o n and c o n c e n t r a t i o n of i r o n i n an a d j a c e n t s i l i c a t e m elt and 2) t h e n e u t r a l i z a t i o n of i r o n -b e a r i n g s o l u t i o n s . E xperiments by O v c h i n n i k o v (1959) have demonstrated t h a t i r o n , among o t h e r m e t a l s , s e p a r a t e s from a b a s a l t i c or g r a n i t i c melt f u s e d w i t h l i m e s t o n e . From a s t u d y o f s i l i c a t e m e l t s i n g e n e r a l , O v c h i n n i k o v c o n c l u d e d t h a t a s s i m i l a t i o n of l i m e s t o n e r e s u l t s i n c o a l e s c e n c e o f i r o n atoms d i s s o l v e d i n the m e l t . E x i s t e n c e o f a t o m i c , as w e l l as i o n i c , p a r t i c l e s i n a s i l i c a t e melt has been demonstrated by s e v e r a l i n v e s t i -g a t o r s (see d i s c u s s i o n i n Ovchinnikov,1 9 6 0 ). The p a r t i c l e s of i r o n c o a l e s c e by a s s i m i l a t i o n o f l i m e s t o n e , are c a r r i e d t o the upper p a r t s o f t h e melt and, depending on t h e p a r t i a l oxygen p r e s s u r e , form c r y s t a l s o f e i t h e r m e t a l l i c i r o n , m a g n e t i t e , or h e m a t i t e (Ovchinnikov, 1 9 5 9)• D i s s o c i a t i o n of l i m e s t o n e l i b e r a t e s gas bubbles which c a r r y i r o n p a r t i c l e s -126-upward i n a p r o c e s s analogous t o f r o t h f l o t a t i o n . O v c h i n n i k o v (I960) found t h a t when b a s a l t and l i m e -stone were f u s e d , the b a s a l t became p a l e green a t i t s c o n t a c t w i t h a p i e c e o f l i m e s t o n e . A n a l y s i s of t h i s green zone showed t h a t i t was i m p o v e r i s h e d i n s i l i c a , a l u m i n a , i r o n , magnesium, sodium, and p o t a s s i u m . C a l c i u m , on t h e o t h e r hand, i n c r e a s e d more than t w o - f o l d i n t h e green zone. These c h e m i c a l changes are almost i d e n t i c a l t o those found a c r o s s t h e c o n t a c t between G i l l i e s q u a r t z monzonite and l i m e s t o n e (Table 5) . Moreover, m a g n e t i t e formed i n the f u s i o n experiments c o n t a i n e d no t i t a n i u m , but copper i n c r e a s e d t w e n t y - f o l d . The e x p e r i m e n t a l l y -produced r e l a t i v e c o n c e n t r a t i o n s of t h e s e elements are v e r y s i m i l a r t o t h e i r r e l a t i v e c o n c e n t r a t i o n s i n c o n t a c t metasomatic m a g n e t i t e o r e b o d i e s . I r o n w h i c h has been s e p a r a t e d from a s i l i c a t e m elt i s c a r r i e d toward t h e margins by gas bubbles where i t comes i n c o n t a c t w i t h aqueous s o l u t i o n s . These can t h e n d i s s o l v e the i r o n and c a r r y i t t o the c o u n t r y r o c k as c h l o r i d e s . As p r e v i o u s l y d i s c u s s e d , these s o l u t i o n s have a p'H l e s s than 7 and a r e p r o b a b l y a c i d i c . By n e u t r a l i z i n g t h e s e s o l u t i o n s , l i m e s t o n e promotes d e p o s i t i o n of m a g n e t i t e . As more c a r b o n a t e i s d i s s o l v e d , the pH r i s e s and the s t a b i l i t y of m a g n e t i t e i n c r e a s e s . The r e a c t i o n s which i n v o l v e complex io n s -127-( e q u a t i o n ( 2 ) ) , m a g n e t i t e i s s i m i l a r l y s t a b i l i z e d by the presence of excess c a r b o n a t e . For those d e p o s i t s i n v o l c a n i c r o c k s , n e u t r a l i z a t i o n i s brought about i n a s i m i l a r manner (e. g . o r e b o d i e s such as I r o n H i l l , F.L., and K l a a n c h , a l t h o u g h i n c o n t a c t w i t h l i m e s t o n e , have l a r g e l y r e p l a c e d b r e c c i a t e d v o l c a n i c r o c k ) . I f kept i n c o n t a c t w i t h l i m e s t o n e t h r o u g h f i s s u r e s or I n t e r g r a n u l a r b o u n d a r i e s , ore f l u i d s which f i l l f r a c t u r e s i n , or r e p l a c e , a n d e s i t e w i l l be n e u t r a l i z e d by d i f f u s i o n . An a n a l o g y i s a l o n g a c i d - f i l l e d tube In c o n t a c t w i t h an u n l i m i t e d s u p p l y of c a r b o n a t e a t one end. The s o l u t i o n i s n e u t r a l i z e d f i r s t at the end n e a r e s t the carbonate but i n time w i l l become n e u t r a l t h r o u g h o u t . In n a t u r e , t h e process of n e u t r a l i z a t i o n of f l u i d s remote from a l i m e s t o n e would be a i d e d by the " s t i r r i n g " a c t i o n o f C 0 2 m i g r a t i n g t h r o u g h the r o c k . P r e c i p i t a t i o n would be most r a p i d i n l i m e s t o n e and s l o w -e s t i n v o l c a n i c r o c k s . Rapid p r e c i p i t a t i o n has been suggested p r e v i o u s l y as a c o n t r i b u t i n g cause of b i r e f r i n g e n c e i n g r a n d i t e g a r n e t s , t h e m a j o r i t y of w h i c h are found i n l i m e s t o n e (pp.60-62). In the absence o f l i m e s t o n e , i r o n c h l o r i d e - b e a r i n g ore f l u i d s may be p a r t l y n e u t r a l i z e d by a l u m i n o - or magnesio-s i l i c a t e s or by c a r b o n a t e - b e a r i n g v o l c a n i c r o c k s . Small d e p o s i t s of d i s s e m i n a t e d m a g n e t i t e , such as are found s c a t t e r e d throughout Karmutsen group v o l c a n i c r o c k s on Vancouver I s l a n d , may have formed i n t h i s manner. - 1 2 8 -M e n t i o n has been made of t h e o c c u r r e n c e o f m a g n e t i t e o r e b o d i e s e x c l u s i v e l y i n the Vancouver group (p.122). T h i s may have, however, a c h e m i c a l e x p l a n a t i o n . In o r d e r f o r a p l u t o n to be i n c o n t a c t w i t h Q u a t s i n o l i m e s t o n e and t o form m a g n e t i t e depos i t s , i t f i r s t must pass through the Karmutsen group. T h i s u n i t i s at l e a s t 10,000 f e e t t h i c k (Mathews and McCammon,1957,p.35) and c o n t a i n s about 3% i r o n (Table 1 3 ) . C o n s e q u e n t l y , an i n t r u s i o n f o r c i n g i t s way through such r o c k would have ample o p p o r t u n i t y t o become a t l e a s t l o c a l l y e n r i c h e d i n i r o n , p a r t i c u l a r l y i n i t s m a r g i n s . Such t h i c k sequences o f i r o n - r i c h v o l c a n i c r e c k s are l a c k i n g among P a l e o z o i c r o c k s and, i n consequence, an i n t r u s i o n i n Permian l i m e s t o n e might not have a s s i m i l a t e d s u f f i c i e n t e xcess i r o n to produce a m a g n e t i t e d e p o s i t . Hydrothermal p r o c e s s e s Metasomatism i s debated a t l e n g t h i n s e v e r a l e x c e l -l e n t papers by L i n d g r e n ( 1 9 2 5 ) , D u f f e l l (1937), H o l s e r ( I 9 I 4 . 7 ) , G a r r e l s and D r e y e r ( 1 9 5 2 ) , and Hanus (I960) among o t h e r s . The p r e s e n t a u t h o r w i l l l i m i t h i s d i s c u s s i o n t o t h e r e l a t i v e importance o f t h e v a r i o u s h y d r o t h e r m a l p r o c e s s e s l e a d i n g t o f o r m a t i o n of m a g n e t i t e d e p o s i t s . -129-Metasomatism i s e s s e n t i a l l y a p r o c e s s of p r a c t i c a l l y s i m u l t a n e o u s c a p i l l a r y s o l u t i o n of a p r e - e x i s t i n g m i n e r a l or r o c k and t h e d e p o s i t i o n of new m a t e r i a l i n i t s p l a c e ( L i n d g r e n , 1933 ,p»91) . T h i s i m p l i e s t h a t metasomatism proceeds i n a s o l i d w i t h no s u p e r c a p i 1 l a r y o p e n i n g s . The volume f o r m e r l y o c c u p i e d by t h e r e p l a c e d m i n e r a l i s e x a c t l y f i l l e d by the metasome. As p o i n t e d out by G a r r e l s and Dreyer (195>2) and Hanus ( I 9 6 0 ) , however, the e x i s t e n c e o f l a r g e c a v i t i e s i n metasomatic o r e -bodies has been noted by s e v e r a l a u t h o r s . I n the p r e s e n t s t u d y , l a r g e p a r t l y - f i l l e d vugs were found i n s k a r n at I r o n H i l l and i n m a g n e t i t e o f t h e Y e l l o w K i d and S h a m r o c k - B l a c k j a c k d e p o s i t s ( P l a t e V I ) . In c o a r s e - g r a i n e d s k a r n , m a g n e t i t e o r c a l c i t e - q u a r t z commonly f i l l s former open spaces between e u h e d r a l garnet c r y s t a l s ( P l a t e s XX, XXI, and X X I I ) . Open-space f i l l i n g i s not i n c l u d e d i n t h e t r a d i t i o n a l d e f i n i t i o n of metasomatism (Lindgren,1 9 3 3)> even the e x i s t e n c e o f open spaces i s not a c c e p t e d . I f open spaces do o c c u r and are f i l l e d by l a t e r m i n e r a l s , then such m i n e r a l s cannot be c o n s i d -ered metasomatic. Large c a v i t i e s can form d u r i n g h y d r o t h e r m a l depos i t i on when volume o f metasome p r e c i p i t a t e d volume o f host d i s s o l v e d -130-Replacement w i l l s t o p when t h i s r a t i o i s g r e a t e r than one ( G a r r e l s and Dreyer, 1 9 5 2 ). At u n i t y , volume o f metasome e x a c t l y equals volume of h o s t d i s s o l v e d and metasomatism, i n i t s t r a d i t i o n a l s e n s e , has o c c u r r e d . R e c o g n i z i n g t h a t some s o - c a l l e d metasomatic r o c k s o n l y p a r t l y f i l l t h e volume f o r m e r l y o c c u p i e d by t h e i r h o s t , Hanus (I960,p.7 3 ) proposed the term s o l v a t e a p p o s i t i o n - "the process of f o r m a t i o n of s o l u t i o n c a v i t i e s of s u p e r c a p i 1 l a r y s i z e and t h e i r s i m u l t a n e o u s but o n l y p a r t i a l f i l l i n g w i t h new m i n e r a l s . I t i s a p r o c e s s c a p a b l e o f f o r m i n g more f r e e space t h a n i t can s i m u l t a n e o u s l y f i l l w i t h newly-formed m i n e r a l s " . S o l v a t e a p p o s i t i o n , metasomatism, and c a v i t y f i l l i n g a r e c o n s i d e r e d to be, i n order o f d e c r e a s i n g importance, the main h y d r o t h e r m a l p r o -cesses of f o r m a t i o n o f the c o n t a c t metasomatic d e p o s i t s s t u d i e d . In b r e c c i a t e d v o l c a n i c r o c k s , narrow v e i n l e t s o f ma g n e t i t e w i t h r o u g h l y matching w a l l s and s h a r p c o n t a c t s ( P l a t e X I I ) i n d i c a t e t h a t c a v i t y f i l l i n g was p r o b a b l y t h e f i r s t p r o c e s s o f emplacement o f s k a r n and m a g n e t i t e i n such r o c k s . As the s e c a v i t i e s were f i l l e d , replacement became the dominant p r o c e s s i n both v o l c a n i c r o c k s and l i m e s t o n e . A c t i v e f l o w o f an o r e - f o r m i n g f l u i d t h r o u g h r o c k t a k e s p l a c e o n l y i n openings o f , s u p e r c a p i 1 l a r y s i z e . I n s m a l l e r openings -131-o c c u p i e d by such f l u i d , movement i s m a i n l y by d i f f u s i o n o f i o n s . E x p e r i m e n t a l evidence of G a r r e l s and D r e y e r (1952) i n d i c a t e s t h a t maximum amounts of m a t e r i a l can d i f f u s e through r o c k s o n l y under c o n d i t i o n s a p p r o x i m a t i n g s t e a d y - s t a t e d i f f u s i o n , such as would be expected i n n a t u r e . Under the p h y s i c a l and c h e m i c a l c o n d i t i o n s of meta-somatism, m i n e r a l r e a c t i o n s are assumed to r e s u l t i n e q u i l i b r i u m among the phases produced. E x i s t i n g c r i t e r i a of c h e m i c a l e q u i l i b r i u m i n r o c k s are based on n e g a t i v e evidence: l a c k of i n c o m p a t i b l e phases and c o n f o r m i t y to G i b b s Phase R u l e . As p o i n t e d out by Zen (I960) c o n f o r m i t y to t h i s R ule i s a n e c e s s a r y , though not s u f f i c i e n t , c o n d i t i o n f o r e q u i l i b r i u m . Eor a r b i t r a r y v a l u e s of temperature and pressure,- a c o n d i t i o n a p p l i c a b l e to a randomly chosen specimen, a r e s t r i c t e d v e r s i o n of the Phase R u l e i s p c' - c" where p i s the number of phases, c' i s the number of indepen-dent components, and c" i s the number of mobile components (Zen,I960,p.167). Eour phases g a r n e t , pyroxene, e p i d o t e , and m a g n e t i t e comprise more than 98 weight p e r c e n t of s k a r n . F u r t h e r m o r e , f i v e independent components S i 0 2 , CaO, (Mg,Fe,Mn)0, ( A l , E e ) p 0 , , and H ?0 comprise more than -132-98 weight p e r c e n t of s k a r n (Table 1 5 ) . Assuming CC^ to be the major mobile component, even the r e s t r i c t e d v e r s i o n of the Phase Rule (above) a p p l i e s . T h i s i s s t r o n g evidence t h a t c h e m i c a l e q u i l i b r i u m was a t t a i n e d d u r i n g s k a r n i f i c a t i o n . Even a ro c k which conforms to the Phase Rule may be out of c h e m i c a l e q u i l i b r i u m i f phases are found t o g e t h e r which have been e x p e r i m e n t a l l y or e m p i r i c a l l y determined to be m u t u a l l y i n c o m p a t i b l e (Zen,1963). I t has been shown p r e v i o u s l y (Chap. I l l ) t h a t s k a r n m i n e r a l s , e v i d e n t l y formed contempor-a n e o u s l y , are indeed c o m p a t i b l e umder the same P , T - c o n d i t i o n s . F u l f i l l m e n t of the above c r i t e r i a i n d i c a t e s o n l y t h a t e q u i l i b r i u m c o u l d have been o b t a i n e d d u r i n g metasomatism but does not prove t h a t e q u i l i b r i u m d i d , i n f a c t , p r e v a i l . F u r t h e r t e s t s , such as the d i s t r i b u t i o n of t r a c e elements among c o e x i s t i n g s k a r n m i n e r a l s ( e . g . K r e t z , 1 9 6 0 ) , are r e q u i r e d to show t h a t e q u i l i b r i u m was a t t a i n e d d u r i n g s k a r n i f i c a t i o n . -133-CHAPTER V - CONCLUSIONS O r i g i n and c l a s s i f i c a t i o n of t h e d e p o s i t s The m a g n e t i t e o r e b o d i e s were formed a d j a c e n t t o p l u t o n s of i n t e r m e d i a t e c o m p o s i t i o n i n response t o c h e m i c a l and p h y s i c a l changes i n t h e o r e - f o r m i n g f l u i d caused i n p a r t by a de c r e a s e i n t e m p e r a t u r e . The immediate source o f the i r o n i n c o n t a c t metasomatic d e p o s i t s i s a nearby i n t r u s i o n . The u l t i m a t e s o u r c e , however, i s v e r y p r o b a b l y the Karmutsen v o l c a n i c r o c k s w h i c h , i n p a r t , have been a s s i m i l a t e d by an ad v a n c i n g p l u t o n . The o r e f l u i d t h a t o r i g i n a t e d i n a nearby i n t r u s i o n as a d i l u t e aqueous s u p e r c r i t i c a l s o l u t i o n c o n s i s t e d m a i n l y of i r o n c h l o r i d e s w i t h l e s s e r amounts of s i l i c a , magnesium, and aluminum. The i n i t i a l t e m p e r a t u r e of the s o l u t i o n s a p p r o x i m a t e d t h a t o f t h e i n t r u s i o n (800-900°C). Movement to the s i t e s o f d e p o s i t i o n was e i t h e r a l o n g the i n t r u s i o n -c o u n t r y r o c k c o n t a c t , r e s u l t i n g i n d e p o s i t s i m m e d i a t e l y a d j a c e n t t o the s t o c k , or a l o n g f a u l t s , r e s u l t i n g i n d e p o s i t s s e v e r a l hundred f e e t from the i n t r u s i v e c o n t a c t . Some o r e -bodie s may a l s o have been formed by s o l u t i o n s m i g r a t i n g outward from the i n t r u s i o n a l o n g a c o n t a c t between l i m e s t o n e and v o l c a n i c r o c k s . -1314--S k a r n i f i c a t i o n , which t o o k p l a c e i n the temperature range 700-550°C, g e n e r a l l y preceded the main s t a g e o f m a g n e t i t e d e p o s i t i o n . C o n f o r m i t y t o Gibbs Phase Rule and non-appearance of i n c o m p a t i b l e phases i s s t r o n g e v i d e n c e t h a t e q u i l i b r i u m was a t t a i n e d d u r i n g s k a r n i f i c a t i o n . N e u t r a l i z a t i o n of i r o n c h l o r i d e s o l u t i o n s by c a l c i t e r e s u l t e d i n p r e c i p i t a t i o n o f m a g n e t i t e i n t h e t e m p e r a t u r e range IL00-5%0°C, Ore f l u i d s , o r i g i n a l l y one phase, p r o b a b l y d e v e l o p e d i n t o a two-phase system at lower t e m p e r a t u r e s . These f l u i d s i n c r e a s e d i n pH by r e a c t i o n w i t h c a l c i t e u n t i l t h e y reached a t l e a s t 7.8, the minimum s t a b i l i t y pH of c a l c i t e . M a g n e t i t e f i r s t f i l l e d c a v i t i e s i n s k a r n and b r e c c i a t e d v o l c a n i c r o c k s ; then d i f f u s i o n i n t o , and replacement o f , v o l c a n i c r o c k s t o o k p l a c e . Where the volume o f h o s t r o c k d i s s o l v e d exceeded the volume of metasome d e p o s i t e d , c a v i t i e s were formed, some of w h i c h were l a t e r f i l l e d by m a g n e t i t e or by p o s t - o r e c a l c i t e and/or q u a r t z . The most f a v o u r a b l e s i t e s of d e p o s i t i o n were a l o n g c o n t a c t s between l i m e s t o n e and v o l c a n i c r o c k , p a r t i c u l a r l y where l o c a l f o l d i n g had b r e c c i a t e d t h e more b r i t t l e igneous r o c k s . B r e c c i a t e d v o l c a n i c r o c k , r e l a t i v e l y more permeable to o r e - f o r m i n g f l u i d s and having a r e l a t i v e l y l a r g e s u r f a c e a r e a , was a p a r t i c u l a r l y f a v o u r a b l e s i t e o f o r e d e p o s i t i o n . - 1 3 5 -L i n d g r e n (1933) c l a s s i f i e d c o n t a c t metasomatic d e p o s i t s as those which were d e p o s i t e d by d i r e c t Igneous emanations, i n c o n t r a s t t o those formed by hot a s c e n d i n g waters of u n c e r t a i n o r i g i n but charged w i t h igneous emanations. The temperatures and p r e s s u r e s which L i n d g r e n c o n s i d e r e d t o be c h a r a c t e r i s t i c o f hypothermal d e p o s i t s a re v e r y s i m i l a r t o those under w h i c h c o n t a c t d e p o s i t s were formed. Hypothermal d e p o s i t s , however, were c o n s i d e r e d by L i n d g r e n t o have formed at g r e a t depth whereas c o n t a c t metasomatism was c o n s i d e r e d to be a r e l a t i v e l y n e a r - s u r f a c e phenomenon. R e c e n t l y , however, Ridge (1958) has suggested a m o d i f i c a t i o n o f L i n d g r e n ' s c l a s s i f i c a t i o n i n which c o n t a c t metasomatic d e p o s i t s a re reg a r d e d as hypothermal d e p o s i t s c h e m i c a l l y c o n c e n t r a t e d i n c a l c a r e o u s r o c k s by h y d r o t h e r m a l s o l u t i o n s w i t h s l o w decrease of temperature and p r e s s u r e . Suggested c o n d i t i o n s o f f o r m a t i o n of t h i s c l a s s a r e : t e m p e r a t u r e - 300-600°C, p r e s s u r e -7 0 0 - 3 5 0 0 atmospheres, depth - 2-10 m i l e s (Ridge, 1 9 5 8 ,pp. 1 9 2 -193)• Inasmuch as the d e p o s i t s o f the p r e s e n t study a r e thought t o have been d e p o s i t e d from aqueous s o l u t i o n s under c o n d i t i o n s o f t e m p e r a t u r e , p r e s s u r e , and depth w i t h i n the l i m i t s suggested by Ridge, t h e y conform to h i s m o d i f i c a t i o n of t h e L i n d g r e n C l a s s i f i c a t i o n o f Ore D e p o s i t s . -136-S u g g e s t i o n s f o r f u r t h e r work 1. S t u d i e s of t h e t r a c e element d i s t r i b u t i o n among c o e x i s t i n g m i n e r a l s would a i d i n e s t a b l i s h i n g whether or not e q u i l i b r i u m was indeed a t t a i n e d d u r i n g f o r m a t i o n o f t h e s e d e p o s i t s . 2. The p r e s s u r e and temperature l i m i t s of ore d e p o s i t i o n suggested i n t h e p r e s e n t study c o u l d be checked by f u r t h e r u s e of t h e p y r i t e - p y r r h o t i t e - a r s e n o p y r I t e "geothermobarometer". 3. The use o f b i r e f r i n g e n t g r a n d i t e g a r n e t as a g e o l o g i c thermometer has been q u e s t i o n e d because i n c l u d e d i m p u r i t i e s can cause b i r e f r i n g e n c e i n n o r m a l l y i s o t r o p i c s i m p l e s a l t s . D e t a i l e d c h e m i c a l and c r y s t a l s t u d i e s a r e r e q u i r e d to determine whether such i m p u r i t i e s may c o n t r i b u t e a l s o t o b i r e f r i n g e n c e of g r a n d i t e g a r n e t . 1+. The a u t h o r has suggested t h a t p h y s i c a l f e a t u r e s such as l o c a l f a u l t s , f o l d s , and v a r i o u s types o f c o n t a c t s are the main f a c t o r s r e q u i r e d f o r l o c a l ore d e p o s i t i o n . These a r e r e l a t i v e l y s m a l l - s c a l e f e a t u r e s which a r e r e c o g n i z e d o n l y by d e t a i l e d mapping of host r o c k s a d j a c e n t t o igneous c o n t a c t s . E x p l o r -a t i o n f o r c o n t a c t metasomatic m a g n e t i t e d e p o s i t s s h o u l d c o n s i s t of d e t a i l e d g e o l o g i c a l and g e o p h y s i c a l surveys a l o n g c o n t a c t s of p l u t o n s and f a v o u r a b l e c o u n t r y r o c k s . - 1 3 7 -REFERENCES AND SELECTED BIBLIOGRAPHY Abrahams,S.C. and Calhoun,B.A. - The low-temperature t r a n s i t i o n 1953 i n m a g n e t i t e - A c t a C r y s t a 1 1 . , v . 6 , 105-106. Allen , V . T . and F a h e y , J . J . - New o c c u r r e n c e s o f m i n e r a l s a t 19^2 I r o n M o u n t a i n , M i s s o u r i - Amer . M i n . , v. 3 7 , 736-714-3. - Some pyroxenes a s s o c i a t e d w i t h p y r o -1957 metasomatic z i n c d e p o s i t s i n Mexico and New Mexico - B u l l . G e o l . Soc. Amer., v . 6 8 , 8 8 I - 8 9 6 . Arnold,R.G. - E q u i l i b r i u m r e l a t i o n s between p y r r h o t i t e and 1962 p y r i t e from 3 2 5°C t o 7l4-3°C. - Econ. G e o l . , v.5 7 , 72-90. and R e i c h e n , L . E . - Measurement o f the me t a l c o n t e n t 1962 of n a t u r a l l y o c c u r r i n g m e t a l - d e f i c i e n t hexagonal p y r r h o t i t e by an X-ray s p a c i n g method - Amer. M i n . , v.1+7, 105-111 . Bacon,W.R. - I r o n - o r e d e p o s i t s o f Vancouver I s l a n d and Texada 1952 I s l a n d - B.C. Dept. o f Mines Ann. Rept., 1952, A217-A218. - I r o n - o r e d e p o s i t s i n c o a s t a l and so u t h w e s t e r n 1956 B r i t i s h Columbia - B.C. Dept. of Mines Ann. Rept., .1956, 125. - G e o l o g y of Lower J e r v i s I n l e t , B.C. - B.C. Dept. 195*7 of Mines Bui 1. 39 Bain,G.W. - A l m a n d i t e and i t s s i g n i f i c a n c e i n the c o n t a c t 1923 zones o f t h e G r e n v i l l e l i m e s t o n e - J o u r . G e o l . , v . 3 1 , 650-668. Barnes,H.L. - Ore s o l u t i o n s - C a r n e g i e I n s t . Wash. Yrbk., v.5 7 , 1958 2314.-2110. - The e f f e c t o f metamorphism on m e t a l d i s t r i b u t i o n 1959 near base metal d e p o s i t s - Econ. Geol.,, v.51+ 919-91+3. - 1 3 8 -_ _ _ _ _ - E q u i l i b r i a i n s u l p h u r - c o n t a i n i n g aqueous s o l u t i o n s 1961 i n t h e system Fe-S-O, and t h e i r c o r r e l a t i o n d u r i n g ore d e p o s i t i o n - Econ. G e o l . , v.5 6 , 61+8-688. - Mechanisms of m i n e r a l z o n i n g - Econ. G e o l . , v.5 7 , T9E2 3 0 - 3 7 . and K u l l e r u d , G . - R e l a t i o n s between c o m p o s i t i o n of 1957a ore f l u i d s and ore s o l u t i o n s - Econ. G e o l . , v.5 2 , 8 2 5 - 8 3 0 ~~ " - E q u i l i b r i a between p y r i t e , 1957b p y r r h o t i t e , m a g n e t i t e , and aqueous s o l u t i o n s -C a r n e g i e I n s t . V/ash. Yr b k . , v.5 9 , 135-137* B a r r e l l , J . - The p h y s i c a l e f f e c t s of c o n t a c t metamorphism -1902 Am. J . S c i . , l+th s e r . , v. 13, 2 7 9 - 2 9 6 . Barth,T.F.W. - T h e o r e t i c a l p e t r o l o g y - John W i l e y and Sons, 1952 I n c . , N.Y., 3 8 7 p . Barton,P.B. - The c h e m i c a l environment of ore d e p o s i t i o n and 1959 the problem of low-temperature ore t r a n s p o r t - i n Researches i n G e o c h e m i s t r y , John W i l e y and Sons, I n c . , Basta,E.Z. - A c c u r a t e d e t e r m i n a t i o n of t h e c e l l dimensions of 1957 m a g n e t i t e - M i n . Mag., v.XXXI, no. 237,14.31-I4J4.I. B a s t i n , E . S . - I n t e r p r e t a t i o n of ore t e x t u r e s - G e o l . Soc. 1950 Amer ., Mem. 1+5. B i r c h , F . , S c h a i r e r , J , F . , and S p i c e r , H . C . - Handbook of p h y s i c a l 191+2 c o n s t a n t s - G e o l . Soc. Amer., Sp. Paper 3 6 . B l a c k , J . M . - I r o n H i l l - B.C. Dept. o f Mines Ann. Rept., 1952, 1952 A 2 2 1 - A 2 2 8 . Bowen,N.L. - The b e h a v i o u r of i n c l u s i o n s i n igneous maqmas -1922 J o u r . G e o l . , v. 3 0 , 5 1 3 - 5 7 0 . - P r o g r e s s i v e metamorphism of s i l i c e o u s l i m e s t o n e 191+0 and d o l o m i t e - J o u r . G e o l . , v.1+8, 255-271+. B o y d e l l , H . C . - Rule of c o l l o i d a l s o l u t i o n s i n the f o r m a t i o n of 1921+/25 m i n e r a l d e p o s i t s - I n s t . M i n . and M e t a l l u r g y T r a n s . , v . 3 l + , 11+5-337. -139-Boyle,R.W. - The geology, geochemisty, and o r i g i n of the g o l d I 1959 d e p o s i t s of the Y e l l o w k n i f e d i s t r i c t - Geo.Surv., Canada, Mem. 3 1 0 . Buddington,A.F. - G r a n i t e emplacement w i t h s p e c i a l r e f e r e n c e 1959 to No r t h America - B u l l . G e o l . Soc. Amer., v. 7 0 , 671-71+8 , F a h e y , J . , and V l i s i d i s , A . - Thermometric and 1955 p e t r o g e n e t i c s i g n i f i c a n c e of t i t a n i f e r o u s m a g n e t i t e - Am. J . S c i . , v . 2 5 3 , 1+97-532. Buerger,M.J. and Washken,E. - Metamorphism of m i n e r a l s - Amer. 191+7 M i n . , v . 3 2 , 2 9 6 - 3 0 8 . Bunn,C.W. - A d s o r p t i o n , o r i e n t e d i n t e r g r o w t h , and mixed c r y s t a l 1933 f o r m a t i o n - P r o c . Roy. Soc. London, v.ll+1, s e r . A , 5 6 7 - 5 9 3 . Burnham,C.W. - Con t a c t metamorphism of magnesium l i m e s t o n e at 1959 Crestmore, C a l i f o r n i a - B u l l . G e o l . Soc. Amer., v . 7 0 , 8 7 9 - 9 2 0 . Buseck,P.B. - Co n t a c t metasomatic d e p o s i t s of Concepcion de I963 Oro, M exico - D i s s e r t a t i o n A b s t r a c t s , v. 2 3 , no.9, 3 3 1 7 - 3 3 1 8 . B u t l e r , B . S . - R e l a t i o n of ore d e p o s i t s t o d i f f e r e n t types of 1915 i n t r u s i v e r o c k s i n Utah - Econ. G e o l . , v. 1 0 , 101-121. - A suggested e x p l a n a t i o n o f the h i g h f e r r i c o x i d e 1923 c o n t e n t of l i m e s t o n e zones - Econ. G e o l . , v . l 8 , 398-1+01+. Campbe11,F.A. - S p h a l e r i t e - p y r r h o t i t e r e l a t i o n s h i p s at Quemont 1963 Mine - Can. Min. , v. 7 , 367-37)+. C a r s t e n s , H . - On the c l o u d i n g o f p l a g i o c l a s e i n c o r o n i t e d meta-1955 d o l e r i t e s - Nor s k G e o l . f i d s s k . , v.3 5 , 129-13)+. Chapman,J.D. - The c l i m a t e o f B r i t i s h Columbia - Paper p r e s e n t e d 1952 to the F i f t h B r i t i s h Columbia N a t u r a l Resources C o n f e r e n c e . Clapp,C.H. - Southe r n Vancouver I s l a n d - G e o l . S u r v . , Canada, 1912 Mem.13. -ll+O-C l a r k , L . A . - The Fe-As-S system: V a r i a t i o n s o f a r s e n o p y r i t e 1959/60 c o m p o s i t i o n as f u n c t i o n s o f T and P - C a r n e g i e I n s t . Wash. Yrbk., v . 5 9 , 1 2 7 - 1 3 0 . - The Fe-As-S system: Phase r e l a t i o n s and a p p l i c a t i o n s I9o0 ~ Econ. G e o l . , v.5 5 , 1314-5-1381; 1631-1652. C o l l i n s , L . G . and Hagner,A.F. - Host r o c k as a source of i r o n , 1959 A u s a b l e Forks m a g n e t i t e d i s t r i c t , N.Y. ( A b s t r a c t ) -Econ. G e o l . , v.51+, 1352. C o l o n y , R . J . - The f i n a l c o n s o l i d a t i o n phenomena i n t h e c r y s t a l -1923 l i z a t i o n of igneous r o c k s - J our . G e o l . . v.3 1 , 1 6 9 - 1 7 8 . Compton,R.R. - Contact metamorphism i n Santa Rosa Range, Nevada -x 9 6 0 B u l l . G e o l . Soc. Amer., v.7 1 , 1383-D+16. Day,A.L. and A l l e n , E . T . - Isomorphism and the t h e r m a l p r o p e r t i e s of 1905 the f e l d s p a r s - C a r n e g i e I n s t . Wash., Pub.31 Deer,W.A., Howie,R.A., and Zussman,J. - Rock f o r m i n g m i n e r a l s , I963 V o l . l+: Framework s i l i c a t e s - Longmans, Green, and Co. L t d . , London, l+35p. Dennen,W.H. - V a r i a t i o n s i n c h e m i c a l c o m p o s i t i o n a c r o s s igneous 1951 c o n t a c t s - B u l l . G e o l . Soc. Amer., v.62, 514-7-558. DeVore,G.W. - Temperature and t h e d i s t r i b u t i o n of t r a c e elements 1953 ( A b s t r a c t ) - B u l l . G e o l . Soc. Amer., v .6 l+ , 11+12. D u f f e l l , S . - D i f f u s i o n and i t s r e l a t i o n to ore d e p o s i t i o n -1937 Econ. G e o l . , v.3 2 , 1+914--510. Eastwood,G.E.P. - Geology of the Kennedy Lake area - B.C. Dept. 1962 of Mines and P e t . Res. Ann. Rept., 1962, 111-121+. and M e r r e t t , J . E . - Benson R i v e r - B.C. Dept. of !961 Mines and P e t . Res. Ann. Rept., 1961 , 9 5 - 9 7 . E h l e r s , E . G . - An i n v e s t i g a t i o n o f the s t a b i l i t y r e l a t i o n s o f the 1953 A l - F e members of t h e e p i d o t e group - J our. G e o l . , v . 6 l , 2 3 1 - 2 5 1 . E l l i s , A . J . - Chemical e q u i l i b r i u m i n magmatic aases - Am.J.Sci., 1957 v . 2 5 5 , I4I6-I+3L -11+1-- The s o l u b i l i t y of carbon d i o x i d e i n water at h i g h 1959a t e m p e r a t u r e s - Am. J . 5c i . f v. 2 5 7 , 217-23!+, - The s o l u b i l i t y of c a l c i t e i n carbon d i o x i d e s o l u t i o n s -1959b Am. J . S c i . , v.2 5 7 , 351+-365. - The s o l u b i l i t y o f c a l c i t e i n sodium c h l o r i d e I963 ' s o l u t i o n s at h i g h temperatures - Am. J . S c i . , v.261, 259-267. and Fyfe,W.S. - The c a l c i t e - w o l l a s t o n i t e e q u i l i b r i u m -1 9 5 ° A m e r . M i n . , v.1+1, 805-807. and Golding,R.M. - The s o l u b i l i t y of carbon d i o x i d e 1963 above 100 C. i n water and NaCl s o l u t i o n s - Am. J . S c i . , v . 2 6 l , 1+7-60. E l v e r , R . B . - The Canadian i r o n ore i n d u s t r y i n 1962 - Dept. of 1963 Mines and Tech. S u r v . , Canada, M i n . I n f o r m . B u l l . MR67. Ernst,W.G. - Diab a s e - g r a n o p h y r e r e l a t i o n s i n t h e Endion s i l l , I960 D u l u t h , Minn. - J o u r . P e t . , v . l , 2 8 6 - 3 0 3 . Faust,G.T. - The f u s i o n r e l a t i o n s of i r o n - o r t h o c l a s e - Amer. 1936 M i n . , v . 2 1 , 7 3 5 - 7 6 3 . F l a s c h e n , S . S . and Osborne,E.F. - S t u d i e s o f the system i r o n 1957 o x i d e - s I l i c a - w a t e r at low oxygen p a r t i a l p r e s s u r e Econ. G e o l . , v. 5 2 , 923-91+3. Flawn,P. - Nomenclature o f the e p i d o t e r o c k - Am. J . S c i . , 1951 v.21+9, 7 6 9 - 7 7 7 . F l i n t , E . P . , McMurdie,H.F., and W e l l s , L . S . - Hydro t h e r m a l and I9I+I X-ray s t u d i e s of the g a r n e t - h y d r o g a r n e t s e r i e s and the r e l a t i o n s h i p of the s e r i e s t o h y d r a t i o n p r o -ducts of p o r t l a n d cement - J o u r . R e s e a r c h U.S. Bur. S t a n d a r d s , v.2 6 , 1 3 - 3 3 . Ford,W.E. - A s t u d y o f the r e l a t i o n s e x i s t i n g between the 1915 c h e m i c a l , o p t i c a l , and othe r p h y s i c a l p r o p e r t i e s of the members o f the garnet group - Am. J . S c i . , v.1+0, 1+th s e r . , 33-1+9. F o s t e r , P . K . - The thermodynamic s t a b i l i t y of i r o n and i t s 1959 compounds in.hydrotherma 1 media - N. Zeal a n d J o u r . S c i . , v . 2 , 1+22. -U+2-F r o n d e l , C . - Dana's System of M i n e r a l o g y , 7 t h Ed., V o l . I I I j 1962 S i l i c a m i n e r a l s - John W i l e y and Sons, N.Y., 33l+P« , Newhouse,W.H., and J a r r e l l , R . F . - S p a t i a l d i s t r i -19I4.2 b u t i o n o f minor elements i n s i n g l e c r y s t a l s - Amer. M i n . , v . 2 7 , 726-714-5. F y l e s , J.T. - Geology of t h e Cowichan Lake a r e a , Vancouver I s l a n d , 1955 B r i t i s h Columbia - B.C. Dept. o f Mines, B u i 1.37 GarreIs,R.M., Dreyer,R.M., and Howland,A.L. - D i f f u s i o n o f ions 191+9 t h r o u g h i n t e r g r a n u l a r spaces i n w a t e r - s a t u r a t e d r o c k s ' B u l l . G e o l . Soc. Amer., v.60, 1 8 0 9 - 1 8 2 8 . and Dreyer,R.M. - Mechanism of l i m e s t o n e r e p l a c e -1952 ment a t low te m p e r a t u r e s and p r e s s u r e s - B u l l . G e o l . Soc. Amer., v.6 3 , 3 2 5 - 3 8 0 . Gehlen,K.V. and K u l l e r u d , G . - The Cu-Fe-S system: P y r i t e -1962 p y r r h o t i t e - c h a l c o p y r i t e r e l a t i o n s - C a r n e g i e I n s t . Wash. Yrbk., v . 6 l , 15I+-155. G i l b e r t , G . - The s i g n i f i c a n c e of h e m a t i t e i n c e r t a i n o re d e p o s i t s -1926 Econ. G e o l . , v.2 1 , 5 6 0 - 5 7 7 . G o l d s c h m i t t , V . M . - On the metasomatic p r o c e s s e s i n s i l i c a t e 1922 r o c k s - Econ. G e o l . , v . 17, 105-123 Goranson,R.W. - The s o l u b i l i t y of wa t e r i n g r a n i t e maqmas -1931 Am. J . S c l ., 5 t h s e r . , v.2 2 , 1+81-502. Greenwood,H.J. - Water p r e s s u r e and t o t a l p r e s s u r e i n metamorphic 1960 r o c k s - C a r n e g i e I n s t . Wash. Yr b k . , v.5 9 , 5 8 - 6 3 . ________ - Metamorphic r e a c t i o n s i n v o l v i n g two v o l a t i l e 1960/51 phases - C a r n e g i e I n s t . Wash. Yr b k . , v . 6 l , 8 2 - 8 5 . - The system NaAlSi2O^-H20|-Argon: T o t a l p r e s s u r e 1961 and w a t e r p r e s s u r e i n metamorphism - J o u r . Geophys. R e s e a r c h , v.6 6 , 3923-391+6. Gunning,H.C. - Geology and m i n e r a l d e p o s i t s o f Q u a t s i n o -1929 Nimpkish a r e a , Vancouver I s l a n d - G e o l . S u r v . , Canada, Sum. Rept., pt . A , 91+-11+3* ___^ - B u t t l e Lake map-area, Vancouver I s l a n d - G e o l . 1930 S u r v . , Canada, Sum. Rept., pt.A, 5 6 - 7 8 . - l b , 3 -- P r e l i m i n a r y r e p o r t on t h e Nimpkish Lake Quadrangle, 1931 Vancouver I s l a n d , B.C. - G e o l . S u r v . , Canada, Sum. Rept., pt.A, 2 2 - 3 5 . Form and mechanism of i n t r u s i o n of the N i m p k i s h 1932 " b a t h o l i t h " - T r a n s. Roy. Soc. Can., 3 r d s e r . , sec.b,, v.26, 289-301L. Z e b a l l o s R i v e r a r e a , Vancouver I s l a n d , B.C. -1933 G e o l . S u r v . , Canada, Sum. Rept., p t . A I I , 2 9 - 5 0 . Hagner,A.F., C o l 1 i n s ,L.G., and. Clemency,C.V. - Host r o c k as a 1963 s o u r c e of m a g n e t i t e , S c o t t mine, S t e r l i n g Lake, N.Y. -Econ. G e o l . , v.5 8 , 7 3 0 - 7 6 8 . Hamilton,D.L., Burnham,C.W., and Osborne,E.F. - The s o l u b i l i t y I96I4. of w a t e r and e f f e c t s of oxygen f u g a c i t y and water c o n t e n t on c r y s t a l l i z a t i o n i n m a f i c magmas -J o u r . P e t . , v . 5 , 2 1 - 3 9 . Hanus,V. - Hydrothermal metasomatism and i t s r e l a t i o n s h i p t o I 9 6 0 o t h e r o r e - f o r m i n g p r o c e s s e s - 21st I n t e r n a t . G e o l . Congress (Norden), p t . 1 6 , 67-7W. H a r k e r , R . I . and T u t t l e , O . F . - S t u d i e s i n t h e system CaO-MgO-1955 COp, p a r t I : The t h e r m a l d i s s o c i a t i o n of c a l c i t e , d o l o m i t e , and m a g n e s i t e - Am. J . S c i . , v.2 5 3 , 2 0 9 - 2 2 !L. - E x p e r i m e n t a l d a t a on the pCO~-T 1956 c u r v e f o r t h e r e a c t i o n : CaCO^ + S i O ? — > C a S i O ^ T CO P - Am. J . S c i . , v . 2 5 1 ; , 239-256-? ^ Hartman,R.J. - C o l l o i d c h e m i s t r y , 2nd Ed. - Houghton M i f f l i n I9I4.7 Co., Cambridge, 5 7 2 p . Hawley,J.E. and Robinson,C. - The supposed o x i d a t i o n of I9I+8 F e3°i4. fay C 0 2 - Econ. G e o l . , v.1+3, 6 0 3 - 6 0 9 . H e i e r , K . - Thermometric and p e t r o g e n e t i c s i g n i f i c a n c e o f 1956 t i t a n i f e r o u s m a g n e t i t e . A d i s c u s s i o n - Am. J . S c i . , v . 2 5 i ; , 5 0 6 - 5 1 0 . Hess,F.L. - T a c t i t e the p r o d u c t o f c o n t a c t metamorphism -1919 Am. J . S c i . , J+th s e r . , V .I4.8, 3 7 7 - 3 7 8 . -114-Hess,H.H. - Pyroxenes o f common m a f i c magmas - Amer. M i n . , 19I+1 v.26, P t . i , 5 1 5 - 5 3 5 ; P t . n , 573-591+. Hickok,W.O. - I r o n ore d e p o s i t s a t C o r n w a l l , Pa. - Econ. G e o l . , 1933 v . 2 8 , 1 9 3 - 2 5 5 . Hoadley,J.W. - Geology and m i n e r a l d e p o s i t s o f the Z e b a l l o s -1953 N i m p k i s h a r e a , Vancouver I s l a n d , B r i t i s h Columbia -, G e o l . Surv.,-Canada, Mem. 272. Hodgman,C.D. - Handbook of c h e m i s t r y and p h y s i c s , 29th Ed. -1958 Chemical Rubber Pub. Co., C l e v e l a n d , O h i o , 3213p. Holland,H.D. - The c h e m i c a l c o m p o s i t i o n o f v e i n m i n e r a l s and 1956 the n a t u r e of the o r e - f o r m i n g f l u i d s - Econ. G e o l . , v . 5 l , 781 - 7 9 7 . - Some a p p l i c a t i o n s of thermochemical data t o 1959 problems of o r e d e p o s i t s - Econ. G e o l . , v.51+, 18)4.-233. Holser,¥.T. - Metasomatic p r o c e s s e s - Econ. G e o l . , v.1+2, 38I+-395. 191+7 - Metamorphism and a s s o c i a t e d m i n e r a l i z a t i o n i n 1950 the P h i l i p s b u r g r e g i o n , Montana - B u l l . G e o l . Soc. Amer., v.61, 1053-1090. and S c h n e e r , C . J . - Hydrotherma1 m a g n e t i t e - B u i 1. l*9oT G e o l . Soc. Amer. , v. 7 2 , 3 6 9 - 3 8 6 . Hutton,C.O. - H y d r o g r o s s u l a r , a new m i n e r a l o f the g a r n e t -191+3 h y d r o g a r n e t s e r i e s - T r a n s . Roy. Soc. New Z e a l a n d , v . 7 3 , 171+-181. J e f f e r y , W . G . - N i m p k i s h Lake - B.C. Dept. of Mines and P e t . 1960a Resources Ann. Rept.. 1960. 101-103. - Empire Development Co. L t d . - B.C. Dept. of 1960b ' Mines and P e t . Resources Ann. Rept., I960, 90-100. and S t e v e n s o n , J . S . - C o l l o f o r m m a g n e t i t e , Empire 1961 d e p o s i t , Vancouver I s l a n d - O i l w e e k , v.12, no.29,3 3 . Johannsen,A. - A d e s c r i p t i v e p e t r o g r a p h y o f the igneous r o c k s 1939 V o l . I : I n t r o d u c t i o n , t e x t u r e s , c l a s s i f i c a t i o n s , and g l o s s a r y (2nd ed.) - The U n i v . o f C h i c a g o P r e s s , C h i c a g o , 111., 3 l 8 p . -11+5-K a l n i n , D . V . - F o r m a t i o n of m a g n e t i t e i n c o n t a c t metasomatic 1962 .magnetite d e p o s i t s - Geochem., no.7 , 722-727. Kennedy,G.C. - C h a r t s f o r t h e c o r r e l a t i o n of o p t i c a l p r o p e r t i e s 191+7 w i t h c h e m i c a l c o m p o s i t i o n of some common r o c k -f o r m i n g m i n e r a l s - Amer. M i n . , v.3 2 , 5&1-573* - E q u i l i b r i u m between v o l a t i l e s and i r o n o x i d e s 191+8 i n igneous r o c k s 529-51+9. Am. J . S c i . , 5 t h s e r . , v. 21+6, 1 9 5 T Kimbal 1,J 1897 - Some a s p e c t s of t h e r o l e of water i n r o c k m e l t s , " i n C r u s t of the E a r t h , Geo 1. Soc. Amer., Sp. Paper 62, .1+89-50+". , - Secondary o c c u r r e n c e s of mag n e t i t e on i s l a n d s of B r i t i s h Columbia by replacement of l i m e s t o n e and by w e a t h e r i n g o f e r u p t i v e s - Amer. G e o l . , v.20, 13-27. Krauskopf,K.B. - The heavy m e t a l c o n t e n t of magmatic vapour at 600°C. - Econ. G e o l . , v.5 2 , 7 8 6 - 8 0 7 . 1957 T 9 3 T TWl K r e t z , R . A . I960 Kuhara,M. 1925 Lamey,C.A. 1961 Lasky,S.G. 1931 - The use of e q u i l i b r i u m c a l c u l a t i o n s i n f i n d i n g the c o m p o s i t i o n o f a magmatic gas phase, i n Researches i n Ge o c h e m i s t r y , John W i l e y and Sons, I n c . , N.Y. - The p o s s i b l e r o l e of v o l a t i l e m e t a l compounds ~ i n ore g e n e s i s - Econ. G e o l . , v. 5 9 , 22-1+5. - The d i s t r i b u t i o n o f c e r t a i n elements among co-e x i s t i n g c a l c i c p y roxenes, c a l c i c a m p h i b o l e s , and b i o t i t e s i n skarns - Geochim. and Cosmochim. A c t a . , v . 2 0 , 161-191 . Experiments on hy d r o t h e r m a l p r e c i p i t a t i o n of ma g n e t i t e and h e m a t i t e - J a p . J o u r . G e o l . and Geog., v.l+, no. 1-2. - Cont a c t metasomatic i r o n d e p o s i t s o f C a l i f o r n i a -B u l l . G e o l . Soc. Amer., v.7 2 , 6 6 9 - 6 7 8 . The systems i r o n o x i d e s : CC>2:CO, and i r o n o x i d e s rlpO:!^, as a p p l i e d t o l i m e s t o n e c o n t a c t d e p o s i t s Econ. G e o l . , v.2 6 , ) +85 - l i 95 . -114.6-Lindgren,W. - A s u g g e s t i o n f o r t h e t e r m i n o l o g y of c e r t a i n 1922 m i n e r a l d e p o s i t s - Econ. G e o l . , v. 17, 292-29)+. - The c o l l o i d a l c h e m i s t r y o f m i n e r a l d e p o s i t s , i n 19214 Theory of a p p l i c a t i o n of c o l l o i d a l b e h a v i o u r , R.H. Bogue - M c G r a w - H i l l Book Co., N.Y. - G e l r e p l a c e m e n t , a new a s p e c t o f metasomatism -192J=T P r o c . Nat. Acad. S c i . , U.S., v. 11, 5 - 1 1 . - Metasomatism - B u l l . G e o l . Soc. Amer., v.3 6 , 1923 21+7-261. L i n d l e y , A . L . G . and Brown,F.H.S. - F a i l u r e o f a 60 MW steam 1958 t u r b i n e - Eng. D i g e s t , v.I4, no. 10, 36-1+1. L i n d m e r , J . L . and Gruner,J.W. - A c t i o n of a l k a l i s u l p h i d e 1939 s o l u t i o n s on m i n e r a l s at e l e v a t e d temperature -Econ. G e o l . , v.3)4, 5 3 7 - 5 6 0 . MacGregor, A.G. - Clouded f e l d s p a r s and t h e r m a l metamorphism -1931 M i n . Mag., v.22, no.133, 521+-538. Machemer,J,F. - The a p p l i c a t i o n of Eh-pH t o metasomatic 1959 d e p o s i t s - Econ. G e o l . , v.51+, 1122-1125-Mackay,R.A. - The c o n t r o l o f impounding s t r u c t u r e s on ore 19)46 d e p o s i t s - Econ. G e o l . , V . J 4 I , 13-1+6. M a c k i n , J . H . - Geology and i r o n ore d e p o s i t s o f t h e G r a n i t e 195)+ Mountain a r e a , I r o n County, Utah - U.S. G e o l . Surv. M i n . I n v e s t . F i e l d S t u d i e s , MF TT+. MarakushevjA.A. - O x i d a t i o n - r e d u c t i o n p r o c e s s e s and t h e a c i d i t y 1959 of postmagmatic s o l u t i o n s - Geochem., no.5 , 2 5 3 - 2 6 1 . Marmo,V. - On the TIO2 c o n t e n t o f m a g n e t i t e s as a p e t r o g e n e t i c 1959 h i n t - Am. J . S c i . , v.2 5 7 , 11+1+-11+9. Mathews , V/. H. and McCammon, J , W. - C a l c a r e o u s d e p o s i t s o f s o u t h -1957 w e s t e r n B r i t i s h Columbia - B.C. Dept. of M i n e s , Bu 11.1+0 . M e r r i n , S . - S y n t h e s i s of e p i d o t e and i t s apparent P-T s t a b i l i t y 1960 c u r v e ( A b s t r a c t ) - Bui 1. G e o l . Soc. Amer., v.7 1 , 1929. - 1 U 7 -Moore,E.S. - A ma g n e t i t e v e i n of abnormal type - Econ. Geo 1 . , 1932 v.2 7 , 3 8 7 - 3 9 0 . Morey,G.W. - A c t i o n of hot water on some ca r b o n a t e s - Bui 1. 1956 G e o l . Soc. Amer., v.6 7 , 1721. - The s o l u b i l i t y of s o l i d s i n oases - Econ.Geol., TWJ v.52, 225-251. M u e l l e r , R . F . - O x i d a t i o n i n h i g h temperature p e t r o g e n e s i s -1961 Am. J . S c i . , v.259, Lj.60-lj.80. Nockolds,S.R. - The average c o m p o s i t i o n of the major igneous I95I4- r o c k types - B u l l . G e o l . Soc. Amer., v.65, 1 0 0 7 - 1 0 3 2 . Ohle,E.L. - The i n f l u e n c e o f p e r m e a b i l i t y on ore d i s t r i b u t i o n l§5l i n l i m e s t o n e and d o l o m i t e - Econ. G e o l . , v.1+6, 6 6 7 - 7 0 6 ; 8 7 1 - 9 0 8 . 01sen,E. - E q u i l i b r i u m c a l c u l a t i o n s i n the system Mq, Fe, S i , 1963 C, H, and Ni - Am. J . S c i ., v.2 6 1 , 91+3-956. Osborne,E.F. - R o l e o f oxygen p r e s s u r e i n t h e c r y s t a l l i z a t i o n 1959 and d i f f e r e n t i a t i o n of b a s a l t i c maqma - Am. J . S c i . , v . 2 5 7 , 609-61+.7 • O v c h i n n i k o v , L . N . - E x p e r i m e n t a l s t u d y of the pr o c e s s e s o f ore 1959 g e n e s i s - A c t a G e o l o g i c a , Acad. S c i e n t a r i u m H u n g a r i c a e , Tomus V. • - Some r e g u l a r phenomena i n the magmatogene 1960 ore g e n e s i s - 21st I n t e r n a t . G e o l . Conqress (Norden), p t . 1 6 , 7-16. ~ P a r k , J r . , C . F . - A ma g n e t i t e " f l o w " i n n o r t h e r n C h i l e - Econ. 1961 G e o l . , v . 5 6 , 1+31-1+1+1. P a u l i t s c h , P . - Z w e i a c h s i g e K a l z i t e und Gef u g e r e g e l u n g - M i n . 1951 P e t r . M i t t . (Tschermak), 3 r d s e r . , v.2, 180. Peterson,D.W. - D e s c r i p t i v e m o d a 1 • c l a s s i f i c a t i o n o f igneous 1961 r o c k s - Geot imes, v.5, no.6 , 3 0 - 3 6 . P h i l l i p s , B . and Muan,A. - S t a b i l i t y r e l a t i o n s o f i r o n o x i d e s -I960 J o u r . Phys. Chem., v. 61+, 11+51-11+53. P i s t o r i u s , C . W . F . T . and Kennedy,G.C. - S t a b i l i t y r e l a t i o n s of 1962 g r o s s u l a r i t e and h y d r o - g r o s s u l a r i t e a t h i g h temp-a t u r e s and p r e s s u r e s - Am. J . S c i . , v.2 5 8 , 21+7-257. -11+8-P o l d e r v a a r t , A . and G i l k e y , A . K . - On cl o u d e d D l a q i c c l a s e - Amer. 1951+ M i n . , v.39, 75-91. ' P r e s c o t t , B . - Some o b s e r v a t i o n s on c o n t a c t metamorphic ore 1915 d e p o s i t s - Econ. Geo 1., v. 1 0 , 55-69. Ridge,J.D. - Replacement and the e q u a t i n g of volume and weight -191+9 J o u r . G e o l . , v.57, 522-51+9. - S e l e c t e d b i b l i o g r a p h i e s of hy d r o t h e r m a l and mag-1958 m a t i c m i n e r a l d e p o s i t s - G e o l . Soc. Amer., Mem.75. Roedder,E., Ingram,B., and Hall,W.E. - S t u d i e s o f f l u i d I963 i n c l u s i o n s I I I : E x t r a c t i o n and q u a n t i t a t i v e a n a l y s i s of i n c l u s i o n s i n the m i l l i g r a m range - Econ. G e o l . , v . 5 8 , 353-371+. ~ Rooksby,H.P. and Wi11 is,B.T.H. - The low-temperature c r y s t a l 1953 form of m a g n e t i t e - A c t a C r y s t a l 1., v. 6 , 5 6 5 - 5 6 6 . R o s e n q v i s t , I . T . - I n v e s t i g a t i o n s i n t h e c r y s t a l c h e m i s t r y of 1951 s i l i c a t e s I I I . The r e l a t i o n h e m a t i t e - m i c r o c 1 i n e -Norsk G e o l . T i d s s k r . , v.2 9 , 6 5 - 7 6 . Rove,O.N. - Some p h y s i c a l c h a r a c t e r i s t i c s o f c e r t a i n f a v o u r -191+7 a b l e and u n f a v o u r a b l e o re h o r i z o n s - Econ. G e o l . , v.1+2, 57-77; 161-193. R u i z , C . and E r i c k s e n , G . E . - M e t a l l o g e n i c p r o v i n c e s o f C h i l e , 1962 S.A. - Econ. G e o l . , v.57, 9 1 - 1 0 6 . S c h m i t t , H . - The c o n t a c t pyrometasomatic a u r e o l e s - Trans . 191+8 Amer. I n s t . M i n . and Met. Eng., v . 1 7 8 , 13I+-11+2. Schwartz,G.M. - The growth of ma g n e t i t e c r y s t a l s - Econ. G e o l . , 1929 v . 2 l + , 592-600. Shand,S.J. - The g e n e s i s of i n t r u s i v e m a g n e t i t e and r e l a t e d 191+7 ores - Econ. G e o l . , v.1+2, 63L+-636. Shaw,D.M. - Some recommendations r e g a r d i n g metamorphic nomen-1957 c l a t u r e - G e o l . A s s o c . Canada, v . 9 , 6 9 - 8 1 . S k i n n e r , B . J . - P h y s i c a l p r o p e r t i e s o f the end-members of the 1956 garnet group - Amer. M i n . , v.1+1, I+28-I+36. -11+9-Smith,F.G. - C o m p o s i t i o n o f v e i n f o r m i n g f l u i d s from i n c l u s i o n 19514- data - Econ. G e o l . , v.1+9, 2 0 5 - 2 1 0 . - P h y s i c a l g e o c h e m i s t r y - Addison-Wesley Pub. Co., 19b~3 I n c . , Mass., 62i+p. Ste v e n s o n , J . S . - Geology and m i n e r a l d e p o s i t s o f the Z e b a l l o s 1950 m i n i n g camp, B.C. - B.C. Dept. o f M i n e s , B u l l . 2 7 . Stone,J.G. - Ore ge n e s i s i n t h e N a i c a d i s t r i c t , C hihuaha, 1959 M e x i c o - Econ. G e o l . , v.51+, 1 0 0 2 - IO3I4.. Stose,G.W. and G l a s s , J . J . - Garnet c r y s t a l s i n c a v i t i e s i n 1938 metamorphosed T r i a s s i c c onglomerate i n York County, Pa. - Amer. M i n . , v.2 3 , J 4 . 3 O - l 4 . 3 5 * Stringham,B. - F i e l d s of f o r m a t i o n of some common h y d r o t h e r m a l 1952 a l t e r a t i o n m i n e r a l s - Econ. G e o l . , v.1+7, 661-661+. Sutherland-Brown,A. - Pyrometasomatic i r o n - c o p p e r d e p o s i t s on 1962 the west coast - Western M i n e r , v. 3 5 , no.2 , 1+1+-1+5. and J e f f e r y , W . G . - P r e l i m i n a r y g e o l o g i c a l 1960 map of t h e so u t h e r n Queen C h a r l o t t e I s l a n d s , B.C. and notes on the g e o l o g y - B.C. Dept. o f M i n e s . Swanson,CO. - The g e n e s i s o f th e Texada I s l a n d m a g n e t i t e 1921+ d e p o s i t s - G e o l . S u r v . , Canada, Sum. Rept., p t.A, 106-11+1+. Swanson,H.E. and Tatge,E. - S t a n d a r d X-ray d i f f r a c t i o n powder 1953 p a t t e r n s " - U.S. Nat. Bur. Stand., C i r c . 5 3 9 , v . l , 6 9 - 7 0 Thompson,J.B. - L o c a l e q u i l i b r i u m i n metasomatic p r o c e s s e s , 1959 i n Res earches i n Geochemi s t r y - John W i l e y and Sons, I n c . , N.Y., 511P• Lf;glow,W.L. - A r e v i e w of t h e e x i s t i n g hypotheses on the' o r i g i n 1913 of t h e secondary s i l i c a t e zones a t the c o n t a c t s o f i n t r u s i v e s w i t h , l i m e s t o n e - Econ. G e o l . , v . 8 , P t . I , 1 9 - 5 0 ; P t . I I , 215-231+. - G e n e s i s o f the m a g n e t i t e d e p o s i t s near t h e west 1926 c o a s t o f Vancouver I s l a n d - Econ. G e o l . , v.2 1 , 3 5 2 - 3 6 3 -- 1 5 0 -Umpleby,J.B. - Occurrence o f o r e on l i m e s t o n e s i d e of garnet 1916 zones - U n i v . of C a l i f . Pub., v. 1 0 , 2 5 - 3 7 . ~ Vakhrushev,V.A. - C o l l o f o r m f o r m a t i o n o f garnet and m o l y b d e n i t e 1961 i n ores of t h e Shalym d e p o s i t ( A b s t r a c t ) - Econ. G e o l . , v . 5 9 , 221;. Verhoogen,J. - Thermodynamics o f a magmatic gas phase - U n i v . 19i+9 of C a l i f . Pub., v. 2 8 , 9 1 - 1 3 6 . Vinogradov,A.P. and D o n t s o v a , E . I . - ( I s o t o p i c c o m p o s i t i o n of 1952 oxyqen i n m i n e r a l s of a s k a r n o r i g i n ) - Akad. Navk. USSR D o k l a d y , n.s., v.8 5 , 13I4.I -13U-3. Wahlstrom,E.E. - P e t r o g r a p h i c m i n e r a l o g y - John W i l e y and Sons, 1955 I n c . , N.Y., )+08p. W a l t e r , L . S . - Data on the f u g a c i t y of COp i n m i x t u r e s of COp 1963 and H 2 0 - Am. J . S c i . , v . 2 6 l f 151-156. Weeks,W.F. - A thermochemical s t u d y o f e q u i l i b r i u m r e l a t i o n s 1956 - d u r i n g metamorphism of s i l i c e o u s c a r b o n a t e r o c k s -J o u r . G e o l . , v. 61+, 21+5-270. White,D.E., Anderson,E.T., and Grubbs,D.K. - Geothermal b r i n e 1963 w e l l - S c i e n c e , v. 1 3 9 , 9 1 9 - 9 2 2 . White, Wm.H. - C o r d i l l e r o n t e c t o n i c s i n B r i t i s h Columbia -1959 B u l l . Am. A s s o c . P e t . G e o l . , v.1+3, 60 - 1 0 0 . Winche11,A.N. - Elements of o p t i c a l m i n e r a l o g y P t . I I : D e s c r i p t i o n s 1959 of m i n e r a l s (1+th ed. ) - John W i l e y and Sons, I n c . , N.Y., 5 5 l p . W i n c h e l l , H . - The c o m p o s i t i o n and p h y s i c a l p r o p e r t i e s of garnet -1958 Amer. M i n . , v.[4.3, 595-600. W i t t u r , G . E . - Geology o f the m a g n e t i t e d e p o s i t s o f Empire 1961 development Company, Vancouver I s l a n d , B.C. -Unpub. B.Sc. t h e s i s , U n i v e r s i t y o f B r i t i s h Columbia. W y l l i e , P . J . and T u t t l e , O . F . - M e l t i n g of c a l c i t e i n the presence 1957 of w a t e r - Amer. M i n . , v.l+l+, 1+53-1+59. - E f f e c t s o f carbon d i o x i d e on t h e 1959 m e l t i n g of g r a n i t e and. f e l d s p a r s - Am. J . S c i . , v . 2 5 7 , 61+8-655. - 1 5 1 -- E x p e r i m e n t a l i n v e s t i g a t i o n of 1961 s i 1 i c a t e systems c o n t a i n i n g two v o l a t i l e compon-ents - Am. J . S c i . , v.2 5 9 , 128-11+3. Yoder,H.S. - S t a b i l i t y r e l a t i o n s of g r o s s u l a r i t e - J o u r . G e o l . , 1950 v. 5 8 , 2 2 1 - 2 5 3 . - A l m a n d i t e garnet s t a b i l i t y range ( A b s t r a c t ) -T9F5 Amer. M i n . , v.1+0, 31+2. and T i l l e y , C . E . - N a t u r a l t h o l e i i t e - b a s a l t - w a t e r 1956 system - C a r n e g i e I n s t . Wash. Yrbk. , v.5 5 , 169-171 . - O r i g i n of b a s a l t magmas: An 1962 e x p e r i m e n t a l s t u d y of n a t u r a l and s y n t h e t i c r o c k systems - J o u r . P e t . , v. 3 , 31+2-532. Z e i s , E . C . - The V a l l e y of 1 0 , 0 0 0 Smokes I . The f u m a r o l i c 1 § 2 9 i n c r u s t a t i o n s and t h e i r b e a r i n g on ore d e p o s i t i o n -Nat. Geog. Soc. C o n t r i b . Tech. P a p e r s , Katmai S e r i e s , v . l , no .1+. Zen,E. - Metamorphism o f Lower P a l e o z o i c rocks i n t h e v i c i n i t y I960 of t h e T a c o n i c Range i n w e s t - c e n t r a l Vermont -Amer. M i n . , v.1+5, 1 2 9 - 1 7 5 . - Components, phases, and c r i t e r i a o f c h e m i c a l e q u i -T96"3 l i b r i u m i n roc k s - Am. J . S c i . , v . 2 6 l , 929-91+2. Zwaan,P.C. - On t h e d e t e r m i n a t i o n of pyroxenes by X - r a y 1951+ powder diagrams - L i e d s e G e o l . Med., D e e l 19, 1 6 7 - 2 7 6 . - 1 5 2 -APPEND1X I D e s c r i p t i o n s o f p r o p e r t i e s - 1 5 3 -1. The Argonaut Company L i m i t e d ( I r o n H i l l Mine) The I r o n H i l l p r o p e r t y l i e s southwest o f t h e community o f Campbell R i v e r on t h e east c o a s t of Vancouver I s l a n d ( F i g . l ) . The mine i s on a s m a l l r i d g e r i s i n g about 750 f e e t above t h e southwest shore of Upper Quinsam Lake. M a g n e t i t e was d i s c o v e r e d on t h i s r i d g e e a r l y i n t h e c e n t u r y but l i t t l e was done u n t i l 19U-8 when the Coast I r o n Company a c q u i r e d t h e p r o p e r t y , c a r r i e d out a l i m i t e d d r i l l program, and shipped a s m a l l q u a n t i t y o f o r e . The mine was l e a s e d t o the Argonaut Company e a r l y i n 1951; p r o d u c t i o n began i n August of t h a t y e a r and c o n t i n u e d u n t i l December, 1956. D u r i n g t h i s p e r i o d , 1 , 9 9 8 , 5 2 6 s h o r t tons o f i r o n ore c o n c e n t r a t e were s h i p p e d . L o c a l g e o l o g y In the I r o n H i l l a r ea an e l o n g a t e body of g r a n i t i c r o c k i n t r u d e s s e d i m e n t a r y and v o l c a n i c r o c k s c o n s i d e r e d by Gunning (1930) t o be p a r t of the Vancouver group. The v o l -c a n i c s , r e l a t i v e l y younger than t h e se d i m e n t s , are c o r r e l a t i v e w i t h the Karmutsen group; the s e d i m e n t s , m a i n l y l i m e s t o n e , a re c o r r e l a t i v e w i t h the Q u a t s i n o f o r m a t i o n . The i n t r u s i v e r o c k , named t h e Quinsam d i o r i t e by Gunning, i s o v e r l a i n unconformably elsewhere by Upper C r e t a c e o u s sandstone and was c o n s i d e r e d by -151;-him t o be L a t e J u r a s s i c o r E a r l y C r e t a c e o u s . F i n e - g r a i n e d , d a r k green andes i t e o u t crops on t o p of I r o n H i l l and a l o n g t h e r i d g e t o the s o u t h w e s t . In p l a c e s , the r o c k i s d i s t i n c t l y p o r p h y r i t i c ; s t a r - s h a p e d c l u s t e r s o f f e l d s p a r c r y s t a l s a r e most common but some p h e n o c r y s t s a r e dark green h o r n b l e n d e . P i l l o w - l i k e s t r u c t u r e s were noted i n th e s e r o c k s a l o n g w i t h what appeared t o be f l o w b r e c c i a . F a i n t bedding i n t u f f a c e o u s l a y e r s showed t h a t these rocks d i p northwards at a moderate a n g l e . The r o c k i s f r e s h ; minor a l t e r a t i o n i s shown by a s l i g h t " c l o u d i n g " of p l a g i o c l a s e (seen o n l y i n t h i n s e c t i o n ) and growth of a c t i n o l i t e i n h o r n b l e n d e . The o r i g i n of " c l o u d e d " f e l d s p a r s has been d i s c u s s e d by s e v e r a l a u t h ors (see d i s c u s s i o n , Appendix I I ) . A p o i n t count gave t h e f o l l o w i n g mode: p l a g i o -c l a s e ( A n ^ to An^g) 52.0%, hornblende 37*5%, o t h e r s ( o p a c i t e , sphene) 10.0%. A c h e m i c a l a n a l y s i s i s g i v e n i n T a b l e 13, no. 1. A l t e r n a t i n g grey and w h i t e beds c h a r a c t e r i z e 1imestone o v e r l y i n g the v o l c a n i c r o c k s . R e c r y s t a 1 1 i z a t i o n has a l t e r e d the l i m e s t o n e to medium-grained m a r b l e . Three c h e m i c a l a n a l y s e s show t h a t such marble i s more th a n 97% c a l c i u m c a r b o n a t e (Table l l ; ) . -155-The Quinsam i n t r u s i o n i s seven m i l e s long i n a n o r t h w e s t e r l y d i r e c t i o n and t h r e e m i l e s wide. Gunning (1930) r e c o g n i z e d s e v e r a l phases of t h e i n t r u s i o n but a t I r o n H i l l i t i s a medium-grained, m a s s i v e g r a n o d i o r i t e c o n t a i n i n g e u h e d r a l h o r n b l e n d e c r y s t a l s . In t h i n s e c t i o n , t h e h o r n b l e n d e i s seen t o be l a r g e l y p o i k i o l i t i c and e n c l o s e s s e v e r a l p l a g i o c l a s e c r y s t a l s . P l a g i o c l a s e (An^y t o An^y) and ho r n -blende a r e g e n e r a l l y e u h e d r a l . Quartz and untwinned p o t a s s i u m f e l d s p a r a r e i n t e r s t i c i a 1 . A c c e s s o r y m i n e r a l s a r e sphene, m a g n e t i t e (and/or i l m e n i t e ) , a p a t i t e , s e r i c i t e , c h l o r i t e , e p i d o t e , and z i r c o n . A modal a n a l y s i s o f I r o n H i l l g r a n o d i o r i t e gave: p l a g i o c l a s e 1x7%, q u a r t z 22%, amphibole 19%, p o t a s s i u m f e l d s p a r 9%, a c c e s s o r i e s 2% and o p a c i t e 2%. A ch e m i c a l a n a l y s i s i s g i v e n i n T a b l e 1 2 . Near i t s c o n t a c t w i t h v o l c a n i c r o c k s , t h e g r a n o d i o r i t e c o n t a i n s many d a r k - c o l o u r e d i n c l u s i o n s r a n g i n g i n s i z e from 2 t o 10 i n c h e s . Most are a n g u l a r , some are round, but a l l have sharp c o n t a c t s w i t h t h e g r a n i t i c m a t r i x . S e v e r a l o f the fragments c o n t a i n t h e s t a r - s h a p e d c l u s t e r s o f f e l d s p a r c h a r a c t e r i s t i c o f the o v e r l y i n g a n d e s i t e . H i g h l y a l t e r e d green d y k e s , g e n e r a l l y o n l y a f o o t or two wide, c u t through a l l r o c k t y p e s . The dyke- r o c k i s now alm o s t e n t i r e l y composed of l a u m o n t i t e and c a l c i t e p l u s - 1 5 6 -s c a t t e r e d remnants of d i o p s i d i c pyroxene. I t i s d i f f i c u l t t o e s t i m a t e t h e o r i g i n a l r o c k c o m p o s i t i o n but i t may have been not u n l i k e d i a b a s e . A f r e s h d i a b a s e dyke o u t c r o p s i n the bed of G r a n i t e C reek a few hundred f e e t n o r t h of the open p i t . Geology of the I r o n H i l l mine .A d e t a i l e d d e s c r i p t i o n of the I r o n H i l l mine was g i v e n by B l a c k (1952) i n w h i c h he s u g g e s t e d the major s t r u c t u r e i s an o v e r t u r n e d s y n c l i n e . The a x i a l p l a n e of t h i s f o l d s t r i k e s n o r t h w e s t e r l y and d i p s to the n o r t h e a s t between I4.5 and 80 d e g r e e s . The beds at b o t h ends o f t h e s y n c l i n e were con-s i d e r e d by B l a c k t o d i p i n w a r d s , t h e r e b y forming a s t r u c t u r a l "low" i n which t h e d e p o s i t was formed. The o r i g i n a l o u t c r o p s formed a rough e l l i p s e , the c e n t r e o f which was composed o f l i m e s t o n e . V o l c a n i c r o c k s surrounded l i m e s t o n e on t h r e e s i d e s and between th e two an i r r e g u l a r zone of m a g n e t i t e and s k a r n was d e v e l o p e d . The l i m e s t o n e was thought by B l a c k t o mark the a pproximate l o c a t i o n of the a x i a l t r a c e of t h e s y n c l i n e . S k a r n obscures most of the 1 i m e s t o n e - v o l e a n i c c o n t a c t but company r e c o r d s show t h a t most of the ore o c c u r r e d as a replacement of v o l c a n i c s r a t h e r t h a n of l i m e s t o n e . Map 1 ( i n p o c k e t ) shows exposures of t h e main r o c k t y p e s a t the time o f t h e w r i t e r ' s v i s i t i n June, 1961. - 1 5 7 -The n o r t h e a s t e r l y d i p o f t h e s o u t h limb of t h e f o l d i s shown by bedding i n the l i m e s t o n e but a t t i t u d e s on the n o r t h limb are o b s c u r e d by i n t e n s e a l t e r a t i o n , m i g m a t i z a t i o n , and s k a r n -i f i c a t i o n . C r o s s - s e c t i o n s of t h e d e p o s i t , based on company d a t a o b t a i n e d b e f o r e and a f t e r B l a c k ' s v i s i t , were c o n s t r u c t e d by t h e w r i t e r . F i g u r e 11 i s a r e p r e s e n t a t i v e c r o s s - s e c t i o n . I t shows a l a r g e , c e n t r a l mass of l i m e s t o n e surrounded on t h r e e s i d e s by v o l c a n i c s which have been m o r e - o r - l e s s r e p l a c e d by i r o n o r e . Most of t h i s ore has developed a l o n g t h e c o n t a c t between l i m e s t o n e and v o l c a n i c rocks and i n t h e t r o u g h formed by the f o l d . A p l a n of the d e p o s i t (Map 1) shows t h e c o n t r o l e x e r t e d by t h i s c o n t a c t on the emplacement of b o t h s k a r n and o r e . F i g u r e 11 i l l u s t r a t e s how t h e i n t r u s i o n of g r a n o d i o r i t e has conformed t o t h e p r e - e x i s t i n g s y n c l i n a l s t r u c t u r e so t h a t the o l d e r r o c k s seem t o form an embayment i n t h e u n d e r l y i n g g r a n i t i c r o c k . T h i s f i g u r e a l s o emphasizes the t h i c k e n i n g of the orebody as the zone of maximum f l e x u r e i n t h e f o l d i s approached. A c o n t o u r map o f t h e t o p o f the g r a n o d i o r i t e body ( F i g . 1 2 ) g r a p h i c a l l y i l l u s t r a t e s t h e s a u c e r - l i k e shape o f the c o n t a c t between sediments and i n t r u s i o n . The form of t h i s d e p r e s s i o n i s v e r y s i m i l a r t o the trough-shaped s t r u c t u r e of the s e d i m e n t a r y r o c k s above the i n t r u s i o n as shown by B l a c k , ( 1 9 5 2 , F i g . 1 7 ) • When F i g u r e 12 i s compared w i t h a c o n t o u r map FIGURE 12 Contour of top of Quinsam granodiorite stock sub-outcrop, Iron Hill mine. FIGURE 13 Contour of first appearance of ore zone above Quinsam granodiorite stock, Iron Hill mine. -161 of t h e f i r s t appearance of s k a r n and ore above g r a n o d i o r i t e ( F i g u r e 1 3 ) , the s i m i l a r i t y between t h e two maps i l l u s t r a t e s the commanding i n f l u e n c e p l a y e d by t h e s e d i m e n t a r y pendant on the emplacement o f ore. Ore d e p o s i t i o n a t I r o n H i l l was e v i d e n t l y c o n t r o l l e d by t h e f o l l o w i n g f e a t u r e s : (a) The c o n t a c t between l i m e s t o n e and v o l c a n i c r o c k s , (b) The " t r o u g h " formed by the f o l d e d s e d i m e n t s . (c) Emplacement of g r a n o d i o r i t e a d j a c e n t t o t h e l i m e s t o n e - v o l c a n i c c o n t a c t . (d) P r e s e r v a t i o n o f the s y n c l i n e e n c l o s e d by the s t o c k . (e) S e l e c t i v e replacement o f v o l c a n i c s a d j a c e n t t o l i m e s t o n e and a l o n g a s y n c l i n a l a x i s . S e l e c t e d b i b l i o g r a p h y B l a c k , J . M . - I r o n H i l l - B.C. Dept. o f Mines Ann. Rept. 1952 1952, A221-A2~2%~. Gunning,H.C. - B u t t l e Lake map a r e a , Vancouver I s l a n d -1930 G e o l . S u r v . , Canada, Sum. Rept. 1930* P t . A, 56-70. Young,G.A. and Uglow,W.L. - The i r o n ores of Canada. V o l . 1 1926 B r i t i s h Columbia and Yukon - G e o l . S u r v . , Canada Econ. G e o l . S e r i e s no.3 , pp.7 3 - 7 8 . A l s o i n c l u d e s r e f e r e n c e s p u b l i s h e d p r i o r to 1926. - 1 6 2 -2 . Texada Mines L i m i t e d Texada I s l a n d i s i n t h e S t r a i t of G e o r g i a about 50 m i l e s n o r t h w e s t of Vancouver. M a g n e t i t e d e p o s i t s occur on the west s i d e o f t h e i s l a n d ( F i g . l ) and can be reached by road from Vananda or B l u b b e r Bay. These d e p o s i t s were among t h e f i r s t t o produce i r o n ore i n B r i t i s h C o l u m b i a . M a g n e t i t e was d i s c o v e r e d i n the n o r t h p a r t of the i s l a n d i n 1873 and was a c q u i r e d by t h e Puget Sound I r o n Company i n 1875. Ore s h i p -ments began i n 1885 and c o n t i n u e d u n t i l 1890. The P r e s c o t t mine was l e a s e d t o t h e P a c i f i c S t e e l Company i n 1901 and shipments to I r o n d a l e , Wash., were resumed f o r about t h r e e y e a r s . The p r o p e r t y was a g a i n l e a s e d i n 1907 and i n t h e f o l l o w i n g year 1000 tons of ore were s h i p p e d from t h e Lake orebody. Spasmodic a c t i v i t y , m a i n l y e x p l o r a t i o n , c o n t i n u e d u n t i l 1916. In 1922 v i r t u a l l y a l l the b u i l d i n g s were d e s t r o y e d by f i r e . In 1951 Texada Mines L i m i t e d purchased the e n t i r e h o l d i n g s of the Puget Sound I r o n Company. P r o d u c t i o n began i n 1952 and a h i g h grade c o n c e n t r a t e has been s h i p p e d s i n c e t h e n . I n 1956, the m i l l i n g p r o c e d u r e was a l t e r e d t o r e c o v e r c h a l c o p y r i t e as a b y - p r o d u c t . Up to 1962, Texada Mines has sh i p p e d 3,896,3i)-7 s h o r t tons o f i r o n ore c o n c e n t r a t e . - 1 6 3 -L o c a l g eology The h o l d i n g s of Texada Mines L i m i t e d i n c l u d e f o u r main o r e b o d i e s o c c u r r i n g a t or near the c o n t a c t o f a g r a n i t i c i n t r u s i o n and v o l c a n i c and sedi m e n t a r y r o c k s . Three main r o c k types are common t o a l l d e p o s i t s : Texada f o r m a t i o n , M a r b l e Bay f o r m a t i o n , and t h e G i l l i e s s t o c k . The M a r b l e Bay f o r m a t i o n l i e s w i t h i n t h e c e n t r a l p a r t o f a l a r g e n o r t h e r l y t o n o r t h -w e s t e r l y p l u n g i n g s y n c l i n e and t h e G i l l i e s stock.was emplaced at o r near the nose o f t h i s s t r u c t u r e . (Mathews and McCammon, 1 9 5 7 ,P.5 5 ) . The Texada f o r m a t i o n c o n s i s t s of dark green t o b l a c k ^ m a s s i v e , f i n e - g r a i n e d f e l d s p a r p o r p h y r y ( a n d e s i t e ) . P h e n o c r y s t s o f f e l d s p a r are g e n e r a l l y about o n e - e i g h t h i n c h long but o c c a s i o n a l l y r e a c h o n e - h a l f i n c h . V e i n s and patches of e p i d o t e occur almost everywhere but are more common near m a g n e t i t e d e p o s i t s . P l a g i o c l a s e and green hornblende form the groundmass. A modal a n a l y s i s gave the f o l l o w i n g : hornblende 62%, p l a g i o c l a s e (Anj^). 29%, . opaci te 2%, o t h e r s ( m a i n l y sphene) 1%. The M a r b l e Bay f o r m a t i o n , up t o 2500 f e e t t h i c k , i s composed almost e x c l u s i v e l y of c a l c a r e o u s r o c k . On the b a s i s of c h e m i c a l c o m p o s i t i o n , the f o r m a t i o n has been sub-d i v i d e d i n t o t h r e e members, each s e v e r a l hundred f e e t t h i c k . -161+-The lower member i s h i g h - c a l c i u m l i m e s t o n e (89% CaCO^), and su c c e e d i n g members become p r o g r e s s i v e l y r i c h e r i n magnesium (Mathews and McCammon,1957,p.53)• M a g n e t i t e d e p o s i t s a r e developed i n the lower member whi c h i s c o m p l e t e l y r e c r y s t a l -l i z e d w i t h bedding a p p e a r i n g o n l y as d i s c o n t i n u o u s grey or b l a c k c o l o u r e d bands. The G i l l i e s i n t r u s i o n i s exposed i n an ar e a of about 13 square m i l e s between Davis Bay and G i l l i e s Bay on the n o r t h -west c o a s t of Texada I s l a n d . The i n t r u s i o n c u t s b o t h Texada and M a r b l e Bay f o r m a t i o n s . Three main r o c k t y p e s have been r e c o g n i z e d i n the s t o c k , d i s t i n g u i s h e d by d i f f e r e n c e s i n c o l o u r , c o m p o s i t i o n , and r e l a t i v e age. The o l d e s t and p r e -dominant type i s medium-grained, grey q u a r t z monzonite. I t g e n e r a l l y has an e q u i g r a n u l a r t e x t u r e but p h e n o c r y s t s o f pyroxene are o c c a s i o n a l l y seen. Sub-angular i n c l u s i o n s of a d a r k e r , f i n e r g r a i n e d rock a r e common, p r o b a b l y r e c r y s t a 1 1 i z e d x e n o l i t h s of Texada f o r m a t i o n . C o n t a c t s w i t h o l d e r rocks are sharp except where obscured by s k a r n . A r e p r e s e n t a t i v e specimen of the q u a r t z monzonite was chosen f o r a n a l y s i s (Table 12 , No.2 ) . A modal a n a l y s i s gave: p l a g i o c l a s e ( A n ^ ) 29%, p o t a s s i u m f e l d s p a r 21+%, q u a r t z 16%, a u g i t e 8%, b i o t i t e 29%, o p a c i t e 5%, a c c e s s o r i e s 10%. - 1 6 5 -Th i s q u a r t z monzonite i s c u t by i r r e g u l a r masses of a 1 i g h t e r - c o l o u r e d r o c k , a l s o l o c a l l y p o r p h y r i t i c , w hich does not c o n t a i n a n g u l a r i n c l u s i o n s . T h i s r o c k has a b l e a c h e d appearance i n hand specimen and t h i n s e c t i o n e x a m i n a t i o n shows t h a t b o t h f e l d s p a r and pyroxene a r e much more a l t e r e d t h a n these m i n e r a l s i n the q u a r t z monzonite. A modal a n a l y s i s gave: potassium f e l d s p a r 1x3%, p l a g i o c l a s e ( A n ^ ) 30%, q u a r t z 11%, m a f i c s 16%. P o t a s h f e l d s p a r i s g e n e r a l l y a l t e r e d t o k a o l i n i t e , p l a g i o c l a s e i s o n l y s l i g h t l y r e p l a c e d by s e r i c i t e , and m a f i c m i n e r a l s ( a u g i t e , h o r n b l e n d e , b i o t i t e ) a r e u n a l t e r e d . The r o c k i s c l a s s i f i e d as monzonite a l t h o u g h the q u a r t z c o n t e n t ( 1 1 % ) . p l a c e s the r o c k near t h e b o r d e r between monzonite and q u a r t z monzonite. The youngest of the t h r e e phases f o r m i n g the G i l l i e s complex i s a p l i t e , r e a d i l y r e c o g n i z e d by i t s p i n k c o l o u r and s h a r p c o n t a c t s w i t h o t h e r phases. I t appears to have f i l l e d f r a c t u r e s i n o l d e r r o c k s . These f r a c t u r e s are g e n e r a l l y not more than f o u r i n c h e s w i d e. The a p l i t e i s a f i n e - g r a i n e d m i x t u r e o f about e q u a l amounts of q u a r t z and o r t h o c l a s e . P l a g i o c l a s e i s p r e s e n t i n amounts up t o 5%; o t h e r m i n e r a l s form l e s s than 2% of the r o c k . P o t a s h f e l d s p a r i s e i t h e r l a r g e l y or c o m p l e t e l y a l t e r e d t o k a o l i n i t e , and p l a g i o c l a s e i s almost e n t i r e l y r e p l a c e d by c l i n o z o i s i t e and s e r i c i t e . I n g e n e r a l , - 1 6 6 -each s u c c e e d i n g phase of t h e G i l l i e s i n t r u s i o n i s more a c i d than t h e one b e f o r e . A l s o , d e u t e r i c a l t e r a t i o n i n c r e a s e s w i t h i n each s u c c e e d i n g phase. These t h r e e igneous r o c k t y p e s are p r e - o r e . L a t e r i n t r u s i v e a c t i v i t y , though p r o b a b l y g e n e t i c a l l y r e l a t e d t o the G i l l i e s s t o c k , i s p o s t - o r e . Two s e t s of dykes r e p r e s e n t these l a s t phases o f igneous a c t i v i t y . The e a r l i e s t o f t h e s e , and the most prominent, i s a n o r t h w e s t e r l y - t r e n d i n g group of f e l d s p a r p o r p h y r y dykes h a v i n g a maximum observed w i d t h of 50 f e e t . The groundmass i s g r e e n - c o l o u r e d and a c c e n t u a t e s w h i t e p l a g i o c l a s e p h e n o c r y s t s w h i c h comprise 1%% t o 20% of the r o c k . About 2% i s pyroxene p h e n o c r y s t s . In t h i n s e c t i o n , p l a g i o c l a s e (An^Q t o A n ^ ) and- pyroxene p h e n o c r y s t s (the l a t t e r l a r g e l y u r a l i t i z e d ) are s urrounded by a f i n e - g r a i n e d groundmass o f s e r i c i t e , p l a g i o c l a s e , h o r n b l e n d e , a p a t i t e , and minor amounts of e p i d o t e . The r o c k c o n t a i n s o c c a s i o n a l l a r g e a n h e d r a l g r a i n s o f q u a r t z . The youngest dykes are f i n e - g r a i n e d green r o c k c o n v e n i e n t l y d e s c r i b e d as " g r e e n s t o n e " . These a r e n o r m a l l y o n l y a f o o t or so wide and were seen c u t t i n g b o t h ore and f e l d s p a r p o r p h y r y . -167-G e o logy of t h e P r e s c o t t mine The P r e s c o t t body i s an i r r e g u l a r l e n s or group o f l e n s e s developed a l o n g the c o n t a c t between G i l l i e s q u a r t z monzonite and M a r b l e Bay l i m e s t o n e ( F i g . l L j . ) . The plunge i s southwards at a s t e e p a n g l e , almost p a r a l l e l to the d i r e c t i o n of d i p o f the i n t r u s i o n - 1 i m e s t o n e c o n t a c t . T h i s c o n t a c t i s almost v e r t i c a l on the e a s t w a l l of the p i t but d i p s southward at about 60° on t h e west w a l l (see Map 2, i n p o c k e t ) . In p l a c e s the ore zone i s i n c o n t a c t w i t h g r a n i t i c r o cks and l i m e s t o n e ( P l a t e I V ) . C o n t a c t s w i t h t h e l a t t e r a r e c h a r a c t e r i s t i c a l l y sharp but those w i t h g r a n i t i c r o c k a r e g e n e r a l l y g r a d a t i o n a l . T h i s i s w e l l shown on t h e west s i d e of the p i t where t h e ore zone ( c e n t r e of p i t ) passes i n t o b a r r e n s k a r n w h i c h , i n t u r n , grades i n t o a l t e r e d q u a r t z monzonite. An i r r e g u l a r envelope o f s k a r n surrounds most of the orebody and s m a l l n o r t h - t r e n d i n g " s h o o t s " of o r e , g e n e r a l l y more or l e s s v e r t i c a l , "break t h r o u g h " t h i s envelope o n l y to p i n c h out away from t h e main zone. The o r e Is m a g n e t i t e - r i c h s k a r n c o n t a i n i n g v e r y i r r e g u l a r - s h a p e d "pods" of c a l c i t e t h r e e i n c h e s t o two f e e t w i d e . Some pods are i n t e r c o n n e c t e d by c a l c i t e v e i n l e t s but many ar e independent of t h e i r n e i g h b o u r s . Most o f the ore i s f i n e - g r a i n e d e x c e p t i n t h e immediate v i c i n i t y of these c a l c i t e -169-pods where the m a g n e t i t e - g a r n e t r o c k r a p i d l y i n c r e a s e s i n g r a i n s i z e . C a l c i t e i s v e r y much more c o a r s e - g r a i n e d than t h e s u r r o u n d i n g s k a r n and m a g n e t i t e ; c l e a v a g e rhombs one t o t h r e e inches a c r o s s are not uncommon. The term " b r e c c i a o r e " has been a p p l i e d t o t h i s type of ore by mine g e o l o g i s t s i n a l l u s i o n t o i t s broken appearance. Ska r n i s l a r g e l y composed of a n d r a d i t e g a r n e t w i t h minor amounts of d i o p s i d e - h e d e n b e r g i t e and e p i d o t e . M a g n e t i t e v e i n l e t s cut s k a r n In many p l a c e s . S u l p h i d e s , g e n e r a l l y p y r i t e and c h a l c o p y r i t e , a r e p r e s e n t o n l y w i t h m a g n e t i t e and appear to be e s s e n t i a l l y contemporaneous w i t h i t . An i r r e g u l a r z o n i n g i n and around the orebody i s e x p r e s s e d by m i n e r a l o g i c a l changes i n both metasomatic and host r o c k s . G e n e r a l l y not more t h a n two s u c c e s s i v e zones are developed a t any one l o c a l i t y i n the p i t and an i n n e r zone may be d i r e c t l y i n c o n t a c t w i t h an o u t e r zone, the i n t e r m e d i a t e zone or zones b e i n g e n t i r e l y a b s e n t . On a broad s c a l e , though, f o u r main zones are p r e s e n t i n t h e P r e s c o t t p i t : Zone 1 - Ore Zone T h i s i s the innermost zone and c o n s t i t u t e s t h e main orebody. I t i s composed e s s e n t i a l l y of i r r e g u l a r pods of m a g n e t i t e - r i c h s k a r n . S u l p h i d e s are r e l a t i v e l y abundant and - 1 7 0 -where t h i s zone i s i n c o n t a c t w i t h l i m e s t o n e , s u l p h i d e m i n e r a l -i z a t i o n m a r k e d l y i n c r e a s e s toward l i m e s t o n e . Zone 2 - S k a r n Zone An i r r e g u l a r zone of g a r n e t - r i c h s k a r n w h o l l y or p a r t l y envelopes the orebody. M a g n e t i t e i s p r e s e n t i n t h i s zone but not n o r m a l l y i n economic c o n c e n t r a t i o n s . S u l p h i d e s are g e n e r a l l y l e s s abundant and amphiboles (commonly a c t i n o l i t e ) make t h e i r f i r s t appearance as s k a r n m i n e r a l s . E p i d o t e i n c r e a s e s toward the o u t e r edge of t h i s zone. The s k a r n i n p l a c e s i s vuggy w i t h c a v i t i e s f i l l e d w i t h i n w a r d - p r o j e c t i n g q u a r t z c r y s t a l s . Where s k a r n i s i n c o n t a c t w i t h l i m e s t o n e , a t h i n zone of a c t i n o l i t e , b o r d e r ed on the o u t s i d e by s u l p h i d e s or h e m a t i t e , i s commonly found. Zone 3 - A l t e r a t i o n Zone T h i s zone i s an area of h y d r o t h e r m a l a l t e r a t i o n i n q u a r t z monzonite and marks the b e g i n n i n g o f replacement o f the i n t r u s i o n by s k a r n . In i d e a l e x p o s u r e s , t h r e e sub-zones are p r e s e n t . The innermost o f these (sub-zone 3 ( a ) ) i s a g a r n e t -e p i d o t e and i s of l i g h t e r c o l o u r t h a n the o u t e r p o r t i o n of Zone 2. O c c a s i o n a l remnants of u n r e p l a c e d p l a g i o c l a s e a r e v i s i b l e . -171-f h i s I s succeeded outward by sub-zone 3(b) w h i c h i s s i m i l a r t o 3(a) except t h a t garnet i s a b s e n t . A g r a n i t i c t e x t u r e , i n h e r i t e d from t h e p a r t l y r e p l a c e d igneous r o c k , becomes d i s t i n g u i s h a b l e ( P l a t e X V I I I ) and e p i d o t e changes from p i s t a c i t e t o c l i n o z o i s i t e . P l a g i o c l a s e and m a f i c pseudomorphs, l a r g e l y composed o f s e r i c i t e , k a o l i n i t e , and s a u s s u r i t e , a r e v i s i b l e even i n hand sample. Sub-zone 3(c) i s marked by the f i r s t appearance o f q u a r t z as a major c o n s t i t u e n t o f t h e r o c k and p l a g i o c l a s e , (average o f t h r e e samples, A n ^ ) l s l e s s a l t e r e d . The r o c k i s e s s e n t i a l l y h y d r o t h e r m a l l y a l t e r e d q u a r t z m o n z o n i t e . A modal a n a l y s i s o f t h i s r o c k gave: p l a g i o c l a s e ( A n ^ ) 31%# q u a r t z 5%, ( a l t e r e d ) p o t a s s i u m f e l d s p a r 2%%, m a f i c m i n e r a l s 31&# o p a c i t e 6%. I n l i m e s t o n e , Zone 3 i s r e p r e s e n t e d by i r r e g u l a r s m a l l unconnected patches o f s k a r n , g e n e r a l l y t o o s m a l l t o be shown on the map. L o c a l l y , s m a l l patches of secondary p y r i t e and J a s p e r i n l i m e s t o n e a r e cut by c a l c i t e v e i n s . Zone k. " U n a l t e r e d Zone T h i s i s t h e outermost zone and i s c h a r a c t e r i z e d by r e l a t i v e l y u n a l t e r e d c o u n t r y r o c k , e i t h e r q u a r t z monzonite o r l i m e s t o n e . In q u a r t z m o n z o n i t e , p l a g i o c l a s e i s s l i g h t l y l e s s - 1 7 2 -c a l i c (An^y) t h a n i n a d j a c e n t sub-zone 3 ( c ) . U n a l t e r e d o r t h o -c l a s e makes i t s f i r s t appearance and q u a r t z i s much more abundant. A l t e r a t i o n i s c o n f i n e d to s l i g h t ch l o r i t i z a t i o n of m a f i c m i n e r a l s ; c h l o r i t e i s absent from sub-zone 3 ( c ) . Limestone i s almost everywhere r e c r y s t a 1 1 i z e d i n t h i s zone but i s o t h e r w i s e unchanged. These zones a r e summarized below: T a b l e 11 P r e s c o t t mine, Texada Island._Genera 1 c h a r a c t e r i s t i c s of zones deve1 oped w i t h i n and around t h e orebody. Zone 1 - Ore Zone m a g n e t i t e ; m a g n e t i t e - r i c h s k a r n ; s u l p h i d e s . Zone 2 - Skarn Zone Sub-zone (a) g a r n e t - r i c h s k a r n Sub-zone (b) e p i d o t e (or a c t i n o l i t e ) f i r s t appears; s u l p h i d e s i n c r e a s e l o c a l l y toward l i m e s t o n e Zone 3 - A l t e r a t i o n Zone 1. In g r a n i t i c r o c k Sub-zone (a) g a r n e t - e p i d o t e s k a r n Sub-zone (b) e p i d o t e - r i c h s k a r n ; no g a r n e t ; g r a n i t i c t e x t u r e ; p l a g i o c l a s e (or pseudomorphs) v i s i b l e . Sub-zone (c) appearance of q u a r t z ; r o c k i s r e c o g n i z a b l e as an a l t e r e d i n t r u s i o n . 2 . In l i m e s t o n e P a t c h y development of s k a r n ; p y r i t e , J a s p e r . Zone 1|. - U n a l t e r e d Zone Fresh q u a r t z monzonite or r e c r y s t a 1 1 i z e d l i m e s t o n e . -173-604-FIGURE 15 Prescott Mine, Texada Island. Diagram showing chemical changes across a contact between quartz monzonite and limestone. Zones correspond to those described in text, Table II. Composition of ore zone was calculated on the basis of 7 5 % magnetite, 2 5 % skarn. -17U--Marked c h e m i c a l changes accompany t h i s m inera l o g i c a 1 z o n i n g . These c h e m i c a l changes are not as abr u p t as the m i n e r a l o g y would suggest and serve to i l l u s t r a t e , i n the g r a n i t i c r o c k s at l e a s t , t h e g r a d a t i o n a l t r a n s i t i o n from igneous t o metasomatic r o c k . The c h e m i c a l v a r i a t i o n i n some of t h e s e zones i s i l l u s t r a t e d i n F i g u r e 15>. F e l d s p a r p o r p h y r y b o d i e s , some d y k e - l i k e i n form, are seen i n c o n t a c t w i t h , and i n at l e a s t one case showed a c h i l l e d border a g a i n s t , s k a r n and m a g n e t i t e . S m a l l greenstone dykes cut m a g n e t i t e , s k a r n , q u a r t z monzonite, l i m e s t o n e , and f e l d s p a r p o r p h y r y . In s e v e r a l cases these dykes a r e o f f - s e t by e a s t - t r e n d i n g , s o u t h - d i p p i n g normal f a u l t s showing at most a d i p - s l i p d i s p l a c e m e n t o f ten f e e t . Geology of t h e Y e l l o w K i d mine The Y e l l o w K i d d e p o s i t , w h i c h i s a replacement of l i m e s t o n e a d j a c e n t t o an i n t r u s i o n , Is a c l a s s i c c o n t a c t metasomatic m a g n e t i t e d e p o s i t . The orebody i s e l l i p t i c a l i n p l a n and t h e longer a x i s s t r i k e s n o r t h , p a r a l l e l t o t h e i n t r u s i v e c o n t a c t ( F i g . l l j - ) . I n v e r t i c a l s e c t i o n t h e d e p o s i t i s p i p e - l i k e i n shape and plunges s o u t h e a s t under the i n t r u s i o n . I t p i t c h e s - 1 7 5 -southward toward the P r e s c o t t mine. The diameter o f the p i p e i s 150 to 200 f e e t and p i t c h l e n g t h i s at l e a s t 800 f e e t . The shape of the orebody and i t s r e l a t i o n t o i n t r u s i o n and l i m e s t o n e a r e shown i n Map 3 ( i n pocket) and i n F i g u r e 16. The ore Is medium-grained m a g n e t i t e c o n t a i n i n g i r r e g u l a r pods of c a l c i t e . These pods may be connected by e l o n g a t e masses of c a l c i t e , r e s u l t i n g i n an i n t e r l o c k i n g n e t -work of c a l c i t e v e i n s and pods surrounded by m a g n e t i t e ( P l a t e V ) . Some c a l c i t e v e i n l e t s a r e f r a c t u r e f i l l i n g s as shown by m a tching w a l l s ; o t h e r v e i n l e t s a r e i r r e g u l a r and t h e i r r e l a t i o n t o m a g n e t i t e i s not c l e a r . T h i s c a l c i t e i s pure w h i t e and c o a r s e -g r a i n e d i n c o n t r a s t to the grey, f i n e r g r a i n e d , banded b l o c k s of u n r e p l a c e d l i m e s t o n e w h i c h occur here and t h e r e i n t h e d e p o s i t . These b l o c k s a r e f r e q u e n t l y e n c l o s e d i n m a g n e t i t e and do not appear to have been r o t a t e d from t h e i r o r i g i n a l p o s i t i o n . P y r i t e and c h a l c o p y r i t e , commonly a s s o c i a t e d w i t h c a l c i t e and p r e s e n t m a i n l y i n the ma/gentite ore zone, extend outward as v e i n s from c a l c i t e pods or v e i n s and c u t m a g n e t i t e . M a s s i v e ore i s surrounded by a d i s c o n t i n u o u s zone of g a r n e t - r i c h s k a r n a few tens of f e e t t h i c k . Where t h i s s k a r n i s i n g r a d a t i o n a l c o n t a c t w i t h a l t e r e d q u a r t z m onzonite, h o r n -blende i n c r e a s e s i n s k a r n toward the c o n t a c t ; e p i d o t e i n c r e a s e s toward the c o n t a c t i n both s k a r n and g r a n i t i c r o c k . -176-- 1 7 7 -In many p l a c e s m a s s i v e , s k a r n - f r e e m a g n e t i t e i s i n d i r e c t c o n t a c t w i t h c r y s t a l l i n e l i m e s t o n e . D i s c o n t i n u o u s grey bands i n l i m e s t o n e , i n t e r p r e t e d as b e d d i n g , a r e p r e s e r v e d r i g h t up t o the ma g n e t i t e - 1 i m e s t o n e c o n t a c t and a r e cut o b l i q u e l y by or e . Commonly a t h i n , d i s c o n t i n u o u s l a y e r o f e u h e d r a l p y r i t e s e p a r a t e s m a g n e t i t e from u n a l t e r e d , l i m e s t o n e ( P l a t e X I ) . G r a n i t i c r o c k forms t h e hanging w a l l of the d e p o s i t and i s s e p a r a t e d from o r e by a t h i n zone of s k a r n or an a l t e r e d phase of the i n t r u s i o n . T h i s a l t e r a t i o n zone ranges i n t h i c k -ness from a few i n c h e s t o s e v e r a l tens o f f e e t and. s k a r n has r e p l a c e d g r a n i t i c r o c k . In an extreme example o f such r e p l a c e -ment, a b l o c k of q u a r t z monzonite a few f e e t i n diameter i s surrounded by massive garnet s k a r n . The a l t e r a t i o n zone i s e x t r e m e l y narrow, t h e change from r e l a t i v e l y f r e s h q u a r t z monzonite to g a r n e t s k a r n can be c o v e r e d w i t h i n t h e l e n g t h of a s i n g l e t h i n s e c t i o n . T h i s a l t e r a t i o n zone was s e p a r a t e d by t h e w r i t e r i n t o f i v e phases: Phase 1 - m a i n l y g a r n e t , minor c a l c i t e . Phase 2 - e p i d o t e and q u a r t z . Phase 3 - p l a g i o c l a s e , m a f i c s appear. Phase I4. - sphene appears a b r u p t l y ; p l a g i o c l a s e and m a f i c s show l i t t l e a l t e r a t i o n . Phase 5 - f r e s h q u a r t z monzonite. - 1 7 8 -Th e s i m i l a r i t y of t h e s e phases to z o n i n g developed i n the P r e s c o t t mine (Table 11) i s s t r i k i n g . Z o ning i n t h e P r e s c o t t body was developed over s e v e r a l tens o f f e e t ; s i m i l a r z o n i n g i n the Y e l l o w K i d was devel o p e d i n l e s s t h a n one i n c h . On the n o r t h w a l l of t h e Y e l l o w K i d p i t a mass of b r i g h t y e l l o w s e r p e n t i n e has r e p l a c e d p a r t of a s m a l l l i m e s t o n e b l o c k e n c l o s e d i n ma g n e t i t e and s k a r n . The s e r p e n t i n e body i s of i r r e g u l a r shape and does not appear to f o l l o w bedding i n l i m e s t o n e . In p l a c e s , i t i s s e p a r a t e d from l i m e s t o n e by m a g n e t i t e which p e n e t r a t e s s e r p e n t i n e . In t h i n s e c t i o n , s e r -p e n t i n e o c c u r s as rounded pseudomorphs r e p l a c i n g g r a n u l a r c a r b o n a t e . About h a l f of e v e r y g r a i n has been c e n t r a l l y r e p l a c e d . Many g r a i n s have a s e r p e n t i n e c e n t r e , c o n s i s t i n g of o u t w a r d - r a d i a t i n g c o l o u r l e s s a c i c u l a r c r y s t a l s , surrounded by a c a l c i t e r i m . The c r y s t a l s have a maximum r e t a r d a t i o n of f i r s t o r d e r y e l l o w , show e i t h e r p o s i t i v e or n e g a t i v e e l o n g a t i o n , and have a moderate o p t i c angles o f n e g a t i v e s i g n . I n some g r a i n s the c e n t r e o f the s e r p e n t i n e i s i s o t r o p i c . The Y e l l o w K i d dyke (Map 3) i s a l a r g e , e s s e n t i a l l y v e r t i c a l f e l d s p a r - p o r p h y r y dyke which s t r i k e s n o r t h w e s t through the n o r t h e r n s e c t i o n o f t h e p i t . S t r i k e - s l i p movement has o c c u r r e d a l o n g t h i s dyke e s p e c i a l l y near the b o r d e r s ; movement i s of t h e or d e r of 200 t o i+OO f e e t . The dyke p o s s i b l y f o l l o w e d - 1 7 9 -an e a r l i e r f a u l t w hich has been r e - a c t i v a t e d . There i s no e v i d e n c e t o i n d i c a t e t h a t t h e " d y k e - f a u l t " i s g e n e t i c a l l y r e l a t e d t o o r e . East-west t r e n d i n g , s o u t h - d i p p i n g normal f a u l t s have d i s p l a c e m e n t s up t o 50 f e e t . G e o l ogy of the Paxton mine The P a x t o n mine i s a l m o s t e n t i r e l y w i t h i n t h e e a s t e r n m argin of t h e G i l l i e s s t o c k ( F i g , 11+.). Limestone on t h e n o r t h w a l l of the p i t (Map JL+, i n pocket) d i p s s o u t h w e s t e r l y toward the s t o c k . The c o n t a c t between M a r b l e Bay l i m e s t o n e and Texada p o r p h y r i t e i s o b l i t e r a t e d by s k a r n but presumably i s p a r a l l e l t o t h e bedding o f f r e s h l i m e s t o n e a few f e e t above t h e s k a r n c o n t a c t ( P l a t e I I I ) . The exposed margin of the s t o c k i s v e r t i c a l and the main ore mass appears t o have formed i n a Wedge between the i n t r u s i o n and t h e southwest d i p p i n g l i m e s t o n e -v o l c a n i c c o n t a c t . High-grade ore r e p l a c e s e i t h e r q u a r t z mon-z o n i t e or a d j a c e n t v o l c a n i c r o c k . Lower grade ore and s k a r n c o n t i n u e n o r t h w a r d as a s u b - h o r i z o n t a l t o n g u e - l i k e p r o j e c t i o n a l o n g t h e l i m e s t o n e - v o l c a n i c c o n t a c t . T h i s d e p o s i t shows z o n i n g outward from the main ore l e n s . The c e n t r e of z o n i n g i s h i g h - g r a d e massive m a g n e t i t e , -i8o-g e n e r a l l y v e r y c o a r s e - g r a i n e d and r e l a t i v e l y f r e e from s k a r n . S m a l l pods o f c a l c i t e c o n t a i n i n g c h a l c o p y r i t e and p y r i t e are found i n t h i s zone. C a l c i t e v e i n l e t s p r o j e c t outward from t h e s e pods i n t o m a g n e t i t e , o f t e n a l o n g c r y s t a l b o u n d a r i e s . M a s s i v e ore grades outward i n t o a mixed m a g n e t i t e and s k a r n zone i n which m a g n e t i t e both v e i n s and r e p l a c e s s k a r n . A t y p i c a l s k a r n -t o - m a g n e t i t e r a t i o i s about 2 : 1. T h i s changes outward i n t o a l t e r e d q u a r t z monzonite on the southwest w a l l or a l t e r e d v o l c a n i c s on the n o r t h e a s t -wa11 o f the p i t . Where replacement of q u a r t z monzonite by s k a r n i s g r a d a t i o n a l , t h e g r a n i t i c t e x t u r e o f t h e i n t r u s i o n i s r e t a i n e d by s k a r n over s h o r t d i s t a n c e s ( P l a t e s I I and X V I I ) . T h i s p r o g r e s s i v e change i s s t r i k i n g l y e x h i b i t e d by hand specimens wherein m a s s i v e , r e d -brown garnet has r e p l a c e d most of t h e m a f i c m i n e r a l s l e a v i n g o n l y w h i t e a l t e r e d p l a g i o c l a s e . Compact, red-brown g a r n e t r e p l a c e s a l l t h r e e phases of t h e G i l l i e s s t o c k . Even a p l i t e , the youngest phase t h a t occurs as dykes has been r e p l a c e d by s k a r n . M i n e r a l i z a t i o n e v i d e n t l y o c c u r r e d a f t e r the b o r d e r zone of t h e p l u t o n had been s o l i d i f i e d and s h a t t e r e d . S u b s e q u e n t l y , metasomatism and ore d e p o s i t i o n t o o k p l a c e . The c o n t a c t of s k a r n w i t h v o l c a n i c r o c k s i s g e n e r a l l y g r a d a t i o n a l over s e v e r a l tens of f e e t but o c c a s i o n a l l y i s s h a r p . -181-I n c o n t r a s t , s k a r n a l w a y s t e r m i n a t e s a b r u p t l y a g a i n s t l i m e -s t o n e ( P l a t e X I ) . T h e a b u n d a n c e o f s u l p h i d e s , p a r t i c u l a r l y p y r i t e , l o c a l l y i n c r e a s e s t o w a r d t h e s k a r n - 1 i m e s t o n e o r s k a r n -v o l c a n i c c o n t a c t . N e a r i t s m a r g i n t h e i n t r u s i o n c o n t a i n s l a r g e b l o c k s o f T e x a d a g r o u p v o l c a n i c s . T h e s e b l o c k s h a v e s h a r p c o n t a c t s w h i c h a r e c r o s s e d b y v e i n s o f e p i d o t e a n d c h a l c o p y r i t e . I n t h e s o u t h e a s t p i t , t h i n s t r i n g e r s o f m o l y b d e n i t e c u t b o t h s k a r n a n d q u a r t z m o n z o n i t e . A d y k e o f f e l d s p a r p o r p h y r y as much as 3 0 f e e t w i d e s t r i k e s t h r o u g h t h e n o r t h w e s t p a r t o f t h e p i t . I n s e v e r a l p l a c e s , t h i s d y k e s h o w e d c h i l l e d b o r d e r s a g a i n s t b o t h s k a r n a n d m a g n e t i t e . S o u t h - d i p p i n g n o r m a l f a u l t s a r e common i n t h e p i t b u t t h e i r m o v e m e n t s w e r e g e n e r a l l y o n l y a f e w f e e t . C n e c u r v e d , s o u t h - d i p p i n g f a u l t o n t h e n o r t h w a l l i s a r e v e r s e f a u l t t h a t ha s d i s p l a c e d t h e f e l d s p a r p o r p h y r y d y k e a b o u t 20 f e e t . G e o l o g y o f t h e L a k e m i n e T h e r e s e r v e s o f t h e L a k e m i n e w e r e e x h a u s t e d i n 1955 -182-and the p i t has been a l l o w e d t o f l o o d ; c o n s e q u e n t l y the w r i t e r c o u l d not s t u d y the d e p o s i t i n d e t a i l . The d e s c r i p t i o n below was c o m p i l e d from l i t e r a t u r e and t h e a u t h o r ' s b r i e f e x a m i n a t i o n o f t h a t p a r t o f t h e p i t above w a t e r . The mine i s 1200 f e e t n o r t h e a s t of the exposed edge of the G i l l i e s complex ( F i g . IJ4.). Replacement has been i n Texada a n d e s i t e a d j a c e n t to i t s c o n t a c t w i t h M a r b l e Bay l i m e -s t o n e . On the west w a l l of t h e p i t , the l i m e s t o n e - v o l c a n i c c o n t a c t i s exposed. V o l c a n i c r o c k s , more or l e s s r e p l a c e d by s k a r n , form th e hanging w a l l of the d e p o s i t . The s t r u c t u r e i s e v i d e n t l y a s y n c l i n e , the south limb of w h i c h i s o v e r t u r n e d t o t h e n o r t h e a s t . Ore has r e p l a c e d v o l c a n i c r o c k a l o n g the a x i a l l i n e of t h e f o l d near the l i m e s t o n e c o n t a c t . The n o r t h e r n p a r t of the orebody, n e a r e s t l i m e s t o n e , i s r i c h e r i n s u l p h i d e s . M c C o n n e l l noted t h a t "a v e i n - s h a p e d l e n s of c h a l c o p y r i t e two to f i v e f e e t i n w i d t h and 60 f e e t l o n g o c c u r r e d wedged i n between a l t e r e d p o r p h y r i t e and c r y s t a l l i n e l i m e s t o n e " ( M c C o n n e l l , 191l4-,p«73) • The Lake mine i l l u s t r a t e s s e v e r a l f e a t u r e s w h i c h c o n t r i b u t e t o an u n d e r s t a n d i n g of t h i s t y p e of d e p o s i t : (1) m i n e r a l i z a t i o n o c c u r r e d i n an a r e a o f maximum f l e x u r e i n an o v e r t u r n e d s y n c l i n e (2) t h e orebody, a l t h o u g h i t can be c o n s i d e r e d a t y p i c a l c o n t a c t metasomatic d e p o s i t , i s found at - 1 8 3 -a c o n s i d e r a b l e d i s t a n c e from an i n t r u s i o n (3) s u l p h i d e m i n e r a l -i z a t i o n i s g r e a t e s t on the " l i m e s t o n e s i d e " of t h e d e p o s i t and {Ix) d e p o s i t i o n of m a g n e t i t e was m a i n l y i n v o l c a n i c r o c k s . S e l e c t e d b i b l i o g r a p h y Bacon,W.R. - P r e s c o t t , P a x t o n and Lake d e p o s i t s - B.C. Dept. 1952 of Mines Ann. Rept. 1952, A218 - A 2 2 T T Mathews,W.H. and McCammon,J.W. - C a l c a r e o u s d e p o s i t s o f 1957 s o u t h w e s t e r n B r i t i s h Columbia - B.C. Dept. of M i n e s , B u l l . I4.O. McConne11,R.G. - Texada I s l a n d , B. C. - G e o l . S u r v . , Canada, 1911+ Memoir 5 8 , 71+-90. Young,G.A. and Uglow,W.L. - The i r o n ores o f Canada, V o l . 1 1926 B r i t i s h Columbia - G e o l . S u r v . , Canada, Econ. G e o l . S e r i e s no. 3 , 86 - 1 0 2 . A l s o i n c l u d e s r e f e r e n c e s p u b l i s h e d p r i o r t o 1926. - l 6 V 3. Empire Development Company L i m i t e d The Empire Company h o l d i n g s are 18 m i l e s southwest of P o r t M c N e i l on the n o r t h e a s t c o a s t of Vancouver I s l a n d ( F i g . 1 ) . The d e p o s i t s a re found at an e l e v a t i o n o f 2500 f e e t on the east s i d e of M e r r y Widow mountain ( F i g . $ ) . M a g n e t i t e has been known i n t h i s a r e a s i n c e t h e end of the l a s t c e n t u r y . In 1928, the Q u a t s i n o Copper-Gold Mines L i m i t e d was formed to p r o s p e c t f o r copper i n t h e a r e a . A c o n t a c t metasomatic c h a l c o p y r i t e - b o r n i t e - m a g n e t i t e d e p o s i t was a l r e a d y b e i n g e x p l o r e d by o t h e r i n t e r e s t s on the nearby p r o p e r t y of Coast Copper Co. L t d . Q u a t s i n o Mines suspended e x p l o r a t i o n i n 1931 out o p e r a t i o n s were resumed i n 1950 on the M e r r y Widow No. 5 c l a i m . C o n s i d e r a b l e m a g n e t i t e was s u b s e q u e n t l y d i s c o v e r e d on t h i s and t h e a d j o i n i n g K i n g f i s h e r F r a c t i o n Crown-granted c l a i m s . The p r o p e r t y was o p t i o n e d t o t h e Empire Development Company L i m i t e d i n 1956» P r o d u c t i o n began i n 1957 and the p r o p e r t y has produced, t o 1962, l ,575,l ) -98 s h o r t tons of ma g n e t i t e c o n c e n t r a t e . L o c a l geology The d e p o s i t s o c c u r i n r o c k s o f the Vancouver group near the m a r g i n o f the Coast Copper s t o c k . Q u a t s i n o l i m e s t o n e , genera 1 l y w e l 1 bedded, s t r i k e s n o r t h e r l y f o r a d i s t a n c e of - 1 8 5 -a b o u t t w o m i l e s a n d d i p s t o t h e w e s t a t a l o w a n g l e . Wes t o f t h e m i n e , t h i s u n i t c o n t i n u e s f o r m o r e t h a n t w e l v e m i l e s , i t s s t r i k e c h a n g i n g t o w e s t o r n o r t h w e s t e r l y . T h e d i p i s s o u t h -w a r d a t a b o u t 15 d e g r e e s . . The c h a n g e i n s t r i k e e x p o s e s a b r o a d , o p e n s y n c l i n e , p l u n g i n g t o t h e s o u t h w e s t , i n t o t h e n o s e o f w h i c h t h e C o a s t C o p p e r g a b b r o s t o c k was i n t r u d e d ( J e f f e r y , 1 9 6 2 ) . N e a r t h i s i n t r u s i o n , e s p e c i a l l y i n l i m e s t o n e , c o m p l e x f o l d i n g w i t h l o c a l o v e r t u r n i n g i s common. The l o w e r p a r t o f t h e B o n a n z a g r o u p o c c u r s as a d i s c o n t i n u o u s " r i m " a r o u n d much o f t h e C o a s t C o p p e r s t o c k . F l o w r o c k i n t h e M e r r y W i d o w p i t a b o u t i+OO f e e t f r o m t h e C o a s t C o p p e r i n t r u s i o n i s d a r k g r e y t o b l a c k i n c o l o u r a n d h o r n f e l s i c i n t e x t u r e . The r o c k c o n t a i n s a b o u t 15% q u a r t z i n a d d i t i o n t o p l a g i o c l a s e a n d a u g i t e a n d i s c o n s i d e r e d t o be h o r n f e l s i z e d d a c i t e . N e a r t h e h e a d w a l l o f t h e M e r r y W i d o w p i t a n d a b o u t 150 f e e t f r o m t h e i n t r u s i o n , a d i s t i n c t l y l a y e r e d r o c k u n i t i n t h e B o n a n z a g r o u p d i p s w e s t w a r d t o w a r d t h e s t o c k . The l a y e r i n g i s c a u s e d b y a l t e r n a t e l i g h t a n d d a r k b a n d s . I n t h i n s e c t i o n , t h e d a r k c o l o u r i s s e e n t o be a r e s u l t o f a v a r i a t i o n i n t h e p r o p o r t i o n o f p y r o x e n e i n e a c h l a y e r . The r e m a i n d e r o f e a c h b a n d i s c o m p o s e d o f p l a g i o c l a s e . J e f f e r y has d e s c r i b e d t h e r o c k as a p l a g i o c l a s e - p y r o x e n e g n e i s s ( I 9 6 0 , p . 9 5 ) , p r o b a b l y a r e c r y s t a 1 1 i z e d p y r o c l a s t i c . - 1 8 6 -The Coast Copper s t o c k o u t c r o p s over an a r e a o f f i v e square m i l e s ; the body i s o v a l - s h a p e d i n p l a n w i t h t h e long a x i s t r e n d i n g n o r t h . The e a s t e r n t w o - t h i r d s i s composed of d i o r i t e - g a b b r o ; the remainder i s monzonite. Steep c o n t a c t s , d i p p i n g outward between 70 and 90 d e g r e e s , are c h a r a c t e r i s t i c o f t h i s s t o c k ( J e f f e r y , I 9 6 0 , p p . 9 2 - 9 5 ) . I n the M e r r y Widow p i t , however, t h i s c o n t a c t d i p s o n l y 55 degrees t o t h e e a s t . I mmediately a d j a c e n t t o the M e r r y Widow orebody and f o r s e v e r a l hundred f e e t west o f i t , the i n t r u s i o n i s c o a r s e - g r a i n e d gabbro c o n t a i n i n g up t o 12% by weight of d i s s e m i n a t e d m a g n e t i t e . A modal a n a l y s i s of a t y p i c a l sample of the Coast Copper s t o c k i s : p l a g i o c l a s e (An^^) 50%, a u g i t e 39%, a c t i n o l i t e 7%, o p a c i t e 2%, a c c e s s o r i e s 2%. A c h e m i c a l a n a l y s i s and norm c a l c u l a t i o n of t h i s sample a r e g i v e n i n T a b l e 12, No. 3 . Greenstone forms dykes, s i l l s , and i r r e g u l a r b o d i e s throughout Q u a t s i n o and Bonanza r o c k s . Such b o d i e s i n Bonanza v o l c a n i c s a r e e x c e e d i n g l y d i f f i c u l t t o d i s t i n g u i s h . The green-stone i s of v a r i a b l e c o m p o s i t i o n but i s m a i n l y formed of p l a g i o -c l a s e l a t h s and a n h e d r a l pyroxene, both t o o f i n e - g r a i n e d t o a l l o w f u r t h e r o p t i c a l i d e n t i f i c a t i o n . L o c a l l y e i t h e r o f these' m i n e r a l s may o c c u r as p h e n o c r y s t s but more commonly t h e y a r e found as m i c r o l i t e s i n an e x t r e m e l y f i n e - g r a i n e d or g l a s s y groundmass. These ro c k s are thought t o r e p r e s e n t an i n t r u s i v e - 1 8 7 -phase of the o v e r l y i n g Bonanza group v o l c a n i c s ( J e f f e r y , I 9 6 0 , p . 9 5 ) « These greenstone b o d i e s a r e p r e - o r e . In the K i n g f i s h e r p i t greenstone dykes i n l i m e s t o n e have boudinage s t r u c t u r e . A s t r i k i n g f e a t u r e i s t h a t i n d i v i d u a l dyke segments have a t h i n r i m of ga r n e t s k a r n . O b v i o u s l y , metasomatism o c c u r r e d subsequent t o both dyke emplacement and d e f o r m a t i o n , perhaps when the Coast Copper s t o c k was i n t r u d e d . The road n o r t h o f the open p i t s has exposed an o v a l -shaped b r e c c i a " p i p e " a few tens o f f e e t i n d i a m e t e r . I t i s composed of a n g u l a r f r a g m e n t s o f grey t o green v o l c a n i c r o c k s u r r o u n d e d by a l i g h t , f i n e - g r a i n e d m a t r i x of q u a r t z , p o t a s h f e l d s p a r , and c h l o r i t e . The fragments v a r y from o n e - e i g h t i n c h t o t w e l v e i n c h e s and each i s rimmed by a narrow b l e a c h e d zone. T h i s o u t e r zone i s m i n e r a l o g i c a 1 l y s i m i l a r to t h e i n n e r p a r t of t h e fragments except t h a t t h e r e i s a complete l a c k of opaque m i n e r a l s i n the r i m . Elsewhere abundant m a g n e t i t e i s d i s s e m i n a t e d throughout the fragments. The ragged p e r i p h e r y of t h e p i p e extends outwards a l o n g d y k e - l i k e tongues of b r e c c i a i n t o massive v o l c a n i c r o c k s . The p i p e i s c u t by greenstone dykes . Two s e t s o f f a u l t s are r e c o g n i z e d i n t h e a r e a . Normal f a u l t s , s t r i k i n g n o r t h and d i p p i n g t o the e a s t , have r e p e a t e d Q u a t s i n o l i m e s t o n e t o t h e e a s t . These f a u l t s a r e not c o n s i d e r e d -188-to have any g e n e t i c r e l a t i o n t o t h e o r e b o d i e s ( J e f f e r y , I 9 6 0 , 1 9 6 2 ) . N o r t h e a s t - t r e n d i n g f a u l t s , d i p p i n g s t e e p l y t o the s o u t h are common i n and around the d e p o s i t s . In most cases d i p - s l i p movement has been l e s s than t e n f e e t and J e f f e r y ( 1 9 6 0,p . 9 6 ) c o n c l u d e d t h a t a t l e a s t some movement t o o k p l a c e a l o n g these f a u l t s a f t e r emplacement o f the Coast Copper s t o c k . I n t h e K i n g f i s h e r p i t , m a g n e t i t e t h a t extends a l o n g one of t h e s e f a u l t s has been b r e c c i a t e d by p o s t - o r e movement and l a t e r h e a l e d by c o a r s e c a l c i t e . These f a u l t s appear to have formed between the time o f gabbro i n t r u s i o n and ore f o r m a t i o n . Ore s o l u t i o n s p o s s i b l y t r a v e r s e d t h e s e channelways; most of the d e p o s i t s i n t h i s area a re c u t by a t l e a s t one of such f a u l t s . I n the K i n g f i s h e r p i t , a t h r u s t f a u l t , d i p p i n g 25 degrees t o the west, has a l l o w e d movement p a r a l l e l t o bedding i n l i m e s t o n e . M a g n e t i t e has been emplaced a l o n g t h i s f a u l t and shows b r e c c i a t i o n s i m i l a r t o ore i n the n o r t h e a s t - t r e n d i n g s t e e p e r f a u l t s . Some p o s t - o r e movement appears t o be i n d i c a t e d here a l s o . G eology of t h e M e r r y Widow mine At the time o f t h e w r i t e r ' s v i s i t i n A u g u s t , 1961, r u b b l e c o v e r e d a l a r g e p a r t of the bench f a c e s and o b s c u r e d the geo l o g y of t h i s p i t , so t h a t a d e t a i l e d g e o l o g i c a l map of the p i t c o u l d not be made. A b r i e f d e s c r i p t i o n of t h e d e p o s i t c o m p i l e d from company and o t h e r d a t a i s g i v e n below. T h i s orebody o c c u r s m a i n l y I n v o l c a n i c r o c k s near a 1 Imes tone c o n t a c t ( F i g. 17). Lenses o f m a g n e t i t e , s e p a r a t e d by b a r r e n v c l c a n i c s and/or s k a r n , l i e para H e i to t h e e a s t w a r d -d i p p i n g I n t r u s i v e w a r g l n . R e l i c t b e d d i n g I n roeta-volcanic r o c k s •dips t o t h e west a t about 2$ degrees. Ore l e n s e s c a t a c r o s s the t r e n d o f the l a y e r e d r o c k s and t h e .form o f t h e d e p o s i t seems t o have been c o n t r o l l e d by the i n t r u s i v e c o n t a c t r a t h e r t h a n by be d d i n g i n t h e sediments. A n o r t h e a s t - t r e n d i ng, s o u t h - d i p p i n g f a u l t , c u t t i n g t h r o u g h t h e west end. o f t h e p i t n e a r gabbro, may have p r o v i d e d a channel-way f o r m i n e r a l i z i n g s o l u t ions » A s t r u c t u r a l wedge, formed by the ea s t w a r d d i p o f t h e s t o c k margin and t h e w e s t e r l y d i p o f the sediments, p r o v i d e d a f a v o u r a b l e l o c u s o f o r e de-p o s i t i o n * Deep d r i l l i n g In the o r e .zone has r e v e a l e d t h a t s e v e r a l s m a l l f o l d s a r e p r e s e n t be low the main d epos i t . ; t h ese may have p r o v i d e d another s t r u c t u r a l c o n t r o l . S u l p h i d e s , ma i n l y c h a l c o p y r i t e and p y r r h o t i t e . , i n c r e a s e i n m a g n e t i t e toward 1 imes tone t o the e a s t * A r s e n o p y r i t e . , p y r i t e , s p h a l e r i t e , and a l i t t l e m a r e a s i t e have a l s o been r e c o g nI zed (wi 11 u r , 1961)» sw NE 2700+-2 6 0 0 -- 2500-„ 2 4 0 0 4 -> o «2300-§2200-UJ 2100-2000-EMPIRE DEVELOPMENT CO. LTD Merry Widow deposit DIAGRAMMATIC SECTION (After Wittur, 1961) S C A L E : - l"= 200' ____] Coast Copper stock - dwrite, gabbro ——~1 Bonanza group- tuff t andesite Quatsino formation- limestone rzzz Magnetite Skarn F I G U R E 17 - 1 9 1 -Geology of t h e K i n g f i s h e r mine T h i s d e p o s i t l i e s e n t i r e l y i n Q u a t s i n o l i m e s t o n e 1000 f e e t n o r t h e a s t of t h e Merry Widow mine. Two s t e e p l y p l u n g i n g c y l i n d e r s o f massive m a g n e t i t e , n e a r l y c i r c u l a r i n s e c t i o n , l i e about 200 f e e t a p a r t and a r e 100 to l£ 0 f e e t i n d i a m e t e r (Map 5 i n p o c k e t ) . These bodies come t o g e t h e r about 200 f e e t below s u r f a c e t o form a Y-shaped d e p o s i t . The orebody p i n c h e s out i n t o m assive l i m e s t o n e i n s e v e r a l downward-pointing p r o -j e c t i o n s . S k a r n i s v i r t u a l l y absent from the K i n g f i s h e r d e p o s i t . S m a l l amounts are found near greenstone bodies but o t h e r w i s e the ore i s composed of massive m a g n e t i t e c o n t a i n i n g i r r e g u l a r p o d - l i k e bodies of w h i t e c a l c i t e . S u l p h i d e s a re a l s o r e l a t i v e l y r a r e . Greenstone s i l l s and dykes c r i s s - c r o s s t h e d e p o s i t i n s e v e r a l d i r e c t i o n s and, on f i r s t e x a m i n a t i o n , appear to be p o s t - o r e . C l o s e r s c r u t i n y , however, shows t h a t m a g n e t i t e v e i n s p e n e t r a t e t h e s e greenstone b o d i e s and l a r g e segments of dykes and s i l l s a r e s e p a r a t e d by m a g n e t i t e ore. Limestone appears t o have been p r e f e r e n t i a l l y r e p l a c e d by m a g n e t i t e ; g r e e n s t o n e has been l e f t as u n r e p l a c e d remnants. S k a r n and m a g n e t i t e a re a l s o found as rims around greenstone dykes and s i l l s a t some d i s t a n c e from the ore-body. - 1 9 2 -M a g n e t i t e , emplaced a l o n g p r e - e x i s t i n g f a u l t s and then b r e c c i a t e d by p o s t - o r e movement, was t h e n h e a l e d by c o a r s e l y c r y s t a l l i n e c a l c i t e . Fragments o f massive m a g n e t i t e , a few inch e s t o s e v e r a l f e e t i n d i a m e t e r , are c o m p l e t e l y surrounded by t h e w h i t e c a l c i t e . Most o f t h e s e fragments l a c k t h e a n g u l a r i t y c h a r a c t e r i s t i c of a b r e c c i a t e d r o c k ( P l a t e X V I I I ) . A l l f r a g m e n t s , however, a l t h o u g h medium t o f i n e - g r a i n e d i n s i d e , a r e rimmed by a t h i n zone o f v e r y c o a r s e - g r a i n e d m a g n e t i t e . T h i s c o a r s e - g r a i n e d m a t e r i a l may c u t t h r o u g h the fragments as v e i n - l i k e p r o j e c t i o n s w h i c h commonly c o n t a i n c e n t r a l w h i t e c a l c i t e i n vugs. The i m p r e s s i o n gained i s t h a t fragments o f m a g n e t i t e have been formed by movement a l o n g a f a u l t ; s i m u l t a n e o u s s o l u t i o n and r e d e p o s i t i o n then t o o k p l a c e a l o n g t h e i r m a r g i n s . R e c r y s t a 1 1 i z a t i o n such as t h i s would r e s u l t i n rounded c o r n e r s of t h e fragments and c o a r s e - g r a i n e d margins. Some fragments o f m a g n e t i t e have been f r a c t u r e d but not s e p a r a t e d i n t o s m a l l e r p i e c e s and t h e s o l u t i o n s have e n t e r e d t h i s c r a c k . The r e s u l t i s a c o a r s e - g r a i n e d " v e i n " c u t t i n g t h r o u g h a f i n e -g r a i n e d fragment. The o u t e r s u r f a c e s o f many fragments o f m a g n e t i t e e x h i b i t t y p i c a l b o t r y o i d a l t e x t u r e , such as found i n m a l a c h i t e , a z u r i t e , g o e t h i t e , e t c . ( P l a t e X V I ) . The e x t e r n a l b o t r y o i d a l form i s convex toward c a l c i t e . T e x t u r e o f t h i s type was a l s o found i n t h e c r o s s - c u t t i n g " v e i n s " of c o a r s e l y c r y s t a l l i n e - 1 9 3 -m a g n e t i t e where t h e rounded s u r f a c e s were convex toward the c e n t r e o f t h e v e i n s . B o t r y o i d a l t e x t u r e has g e n e r a l l y been i n t e r p r e t e d as i n d i c a t i n g p r e c i p i t a t i o n o f t h e m a t e r i a l from a c o l l o i d a l s o l u t i o n ( L i n d g r e n , l92l4.;Boydell, I92I4./25). The g e n e t i c i m p l i c a t i o n s o f t h i s t e x t u r e i n m a g n e t i t e are d i s c u s s e d e l sewhere i n t h i s paper (pp. 7 1 - 7 6 ) . A c c o r d i n g t o i n f o r m a t i o n r e c e i v e d from J . Lamb, company g e o l o g i s t , e a r l y development work showed t h a t m assive m a g n e t i t e f r e q u e n t l y r e t a i n e d t r a c e s o f b e d d i n g a p p a r e n t l y i n h e r i t e d from s u r r o u n d i n g l i m e s t o n e . Coarse and f i n e - g r a i n e d l a y e r s i n m a g n e t i t e c o u l d be f o l l o w e d a l o n g s t r i k e i n t o beds of l i m e s t o n e showing s i m i l a r t e x t u r e . Large s t r u c t u r e s , such as f o l d s , c o u l d a l s o be t r a c e d from l i m e s t o n e i n t o m a s s i v e m a g n e t i t e . T h i s p r e s e r v a t i o n of s t r u c t u r e i s r e m a r k a b l e i n view of the f a c t t h a t the m a g n e t i t e " p i p e s " p l u n g e v e r y n e a r l y p e r p e n d i c u l a r l y t o bedding. T h i s suggests t h a t ore s o l u t i o n s moved a c r o s s t h e l a y e r i n g ; i f so, t h e y would be expected t o o b l i t e r a t e r a t h e r than p r e s e r v e s e d i m e n t a r y and s t r u c t u r a l f e a t u r e s . Other d e p o s i t s In a d d i t i o n to t h e Merry Widow and K i n g f i s h e r mines, s e v e r a l s m a l l e r m a g n e t i t e bodies are f o u n d i n the a r e a . They -194-are b r i e f l y d e s c r i b e d below i n t h e o r d e r i n w h i c h t h e y occur from n o r t h t o s o u t h around the Coast Copper s t o c k (see J e f f e r y , I960,p.9l+- f o r a map showing l o c a t i o n s ) . Raven d e p o s i t The orebody o c c u r s a t the west end of a 1000-foot m i n e r a l i z e d zone i n g r e e n s t o n e . Ore l i e s a l o n g a n o r t h e a s t -t r e n d i n g f a u l t s e p a r a t i n g greenstone and l i m e s t o n e . M i n i n g i n the Raven p i t reached the economic l i m i t i n I960 and the area was c o m p l e t e l y c o v e r e d by waste at the time of t h e w r i t e r ' s v i s i t . A j a x d e p o s i t M a g n e t i t e on t h i s c l a i m o c c u r s about I4.50 f e e t from the Coast Copper s t o c k at t h e c o n t a c t between Q u a t s i n o l i m e s t o n e , Bonanza v o l c a n i c s , and i n t r u s i v e g r e e n s t o n e . One or p o s s i b l y two n o r t h e a s t - s t r i k i n g f a u l t s pass t h r o u g h t h e south end o f the m i n e r a l i z e d zone. Ore i s composed o f e i t h e r f i n e - g r 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 a l t e r e d v o l c a n i c r o c k s or as vuggy m a g n e t i t e i n s k a r n . In s e v e r a l p l a c e s , fragments of a l t e r e d v o l c a n i c r o c k a r e "suspended" i n a m a t r i x of f i n e - g r a i n e d r e d -brown s k a r n . S m a l l b l o c k s of s k a r n , i n t u r n , a r e surrounded by massive m a g n e t i t e . Q u a r t e r - i n c h books o f c h l o r i t e occur i n vuggy clumps thr o u g h o u t massive m a g n e t i t e . - 1 9 5 -S h a m r o c k - B l a c k j a c k d e p o s i t M a g n e t i t e i s e x p o s e d i n s c a t t e r e d s m a l l o u t c r o p s w i t h i n a r i m o f B o n a n z a r o c k s b e t w e e n t h e C o a s t C o p p e r s t o c k a n d Q u a t s i n o l i m e s t o n e . B e d d i n g i n l i m e s t o n e i s v e r t i c a l o r d i p s t o w a r d t h e i n t r u s i o n . The m a r g i n o f t h e s t o c k d i p s \\S d e g r e e s w e s t and t h e wedge o f v o l c a n i c r o c k b e t w e e n l i m e s t o n e a n d i n t r u s i o n h a s b e e n s p o r a d i c a l l y r e p l a c e d b y m a g n e t i t e . O r e i n t h e s e d e p o s i t s i s c h a r a c t e r i s t i c a l l y v u g g y j t h e c a v i t i e s a r e a f e w i n c h e s w i d e a t m o s t , many b e i n g p a r t l y e n c r u s t e d b y i n w a r d - p r o j e c t i n g q u a r t z c r y s t a l s . The r e m a i n i n g s p a c e i n t h e v u g i s e i t h e r v a c a n t o r f i l l e d w i t h c a l c i t e o r c o m p a c t m a s s i v e g o e t h i t e . One q u a r t z - f i l l e d v u g was s u r r o u n d e d b y m a g n e t i t e h a v i n g b o t r y o i d a l t e x t u r e . E a c h b o t r y o i d a l " r o s e t t e " was a b o u t o n e - q u a r t e r i n c h a c r o s s and c o n v e x i n t o t h e v u g . A n i n t e r e s t i n g o u t c r o p o f m a g n e t i t e , t h r e e f e e t b y t w e l v e f e e t , o c c u r s i n c o a r s e l y c r y s t a l l i n e l i m e s t o n e on t h e S h a m r o c k c l a i m . L a y e r s o f m a g n e t i t e u p t o 1 mm i n t h i c k n e s s a l t e r n a t e w i t h c a l c i t e l a y e r s o f s i m i l a r t h i c k n e s s . C o n t i n u i t y i n e a c h l a y e r i s b r o k e n when m a g n e t i t e b r e a k s t h r o u g h an a d j a c e n t c a r b o n a t e l a y e r a n d f u s e s i n a n i r r e g u l a r m a n n e r w i t h t h e n e x t l a y e r o f m a g n e t i t e ( P l a t e X I I I ) . S m a l l f o l d s , a f r a c t i o n o f a n i n c h i n m a g n i t u d e , a r e p r e s e n t i n l a y e r s o f - 1 9 6 -m a g n e t i t e and c a l c i t e 0 . 1 mm i n t h i c k n e s s ( P l a t e X I V ) . Such l a y e r i n g i s narrower t h a n i n l i m e s t o n e o u t s i d e t h e magneti t e u n i t . The o r i g i n of t h i s l a y e r e d s t r u c t u r e i s not c l e a r . I t may be the r e s u l t of s e l e c t i v e replacement o f c e r t a i n l i m e s t o n e beds of m a g n e t i t e but r e c r y s t a l l i z a t i o n has d e s t r o y e d the o r i g i n a l n a t u r e o f t h i s b e d d i n g . J e f f e r y has su g g e s t e d the ma g n e t i t e i n t h i s o u t c r o p has r e p l a c e d some type o f a l g a l s t r u c t u r e ( J e f f e r y , i 9 6 0 , p . 9 9 ) • F o l d e d l i m e s t o n e showing s e l e c t i v e replacement by 1 mm l a y e r s of m a g n e t i t e have been d e s c r i b e d from d e p o s i t s i n C a l i f o r n i a (Lamey,1961,pp.675, F i g . 5 , 6 ) . Photographs i n the paper by Lamey show samples o f t h i s rock w h i c h appear i d e n t i c a l t o samples from the B l a c k j a c k - S h a m r o c k d e p o s i t . In a b r i e f e x p l a n a t i o n of the o r i g i n o f t h i s type o f re p l a c e m e n t , Lamey w r i t e s (p.6 7 5 ) : " . . . . t h i s s e l e c t i v i t y may have r e s u l t e d from a d i f f e r e n c e i n t h e magnesium c o n t e n t of the o r i g i n a l r o c k l a y e r s , the more magnesian ones h a v i n g been s e l e c t i v e l y r e p l a c e d . T h i s i s suggested because m a g n e t i t e r e p l a c e d a n t i g o r i t e and c h o n d r o d i t e in"some d e p o s i t s ; thus a h i g h e r magnesium c o n t e n t of some l a y e r s may have f a c i l i t a t e d r eplacement o f them". - 1 9 7 -S e l e c t e d b i b l i o g r a p h y Bacon,W.R. - Q u a t s i n o Copper-Gold Mines L i m i t e d - B.C. Dept. 1952 of Mines Ann. Rept. 195*2, A 2 2 8 - A 2 3 1 . Eastwood,G.E.P and M e r r e t t , J . E . - Benson R i v e r - B.C. Dept. 1961 of Mines and P e t r o l . Resources Ann. Rept. 1961 , 9 5 - 9 7 . J e f f e r y , W . G . - Empire Development Company L i m i t e d - B.C. Dept. 1960 of Mines and P e t r o l . Resources Ann. Rept. i 9 6 0 , 9 0 - 1 0 0 . - P r e l i m i n a r y g e o l o g i c a l map, A l i c e Lake-Benson 19o~2 Lake a r e a - B.C. Dept. Mines and P e t r o l . R e s o u r c e s . W i t t u r , G . E . - Geology of t h e m a g n e t i t e d e p o s i t s o f Empire 1961 Development Company, Vancouver I s l a n d , B.C. -Unpub. B.Sc. t h e s i s . , U n i v e r s i t y of B r i t i s h C o lumbia. - 1 9 8 -1+. Brynnor Mines L i m i t e d T h i s mine l i e s between Maggie Lake and Kennedy Lake on the west coast of Vancouver I s l a n d , n i n e m i l e s n o r t h e a s t of U c l u e l e t ( F i g . 1 ) . A l o g g i n g road c o n n e c t s the m i n e - s i t e w i t h the A l b e r n i - T o f i n o r o a d on the shore o f Kennedy L a k e . A s t r o n g m agnetic anomaly i n the area was r e p o r t e d by W.F. R o b e r t s o n , P r o v i n c i a l M i n e r a l o g i s t , i n 1902. Noranda E x p l o r a t i o n Company L i m i t e d t o o k over t h e p r o p e r t y i n I 9 6 0 a f t e r the anomaly had been r e - l o c a t e d by d i p - n e e d l e s u r v e y . The l name o f t h e company was l a t e r changed t o Brynnor Mines L i m i t e d , a wholly-owned s u b s i d i a r y of Noranda Mines L i m i t e d . P r o d u c t i o n began i n 1962 and i n t h a t year [(.51,623 s h o r t tons of m a g n e t i t e c o n c e n t r a t e were s h i p p e d . L o c a l g e o l o g y The g e o l o g y of the Kennedy Lake a r e a was v i r t u a l l y unknown u n t i l r e c e n t f i e l d work by o f f i c e r s of the B.C. D e p a r t -ment of Mines and members of the Noranda s t a f f c l a r i f i e d the s t r u c t u r e and p r o v i d e d a b a s i s f o r c o r r e l a t i o n w i t h r o c k s found els e w h e r e on Vancouver I s l a n d . A sequence o f s e d i m e n t a r y and v o l c a n i c rocks exposed s o u t h e a s t o f Kennedy Lake has been t e n t a t i v e l y c o r r e l a t e d w i t h the Vancouver g r o u p . F o s s i l s are l a c k i n g i n the Kennedy Lake - 1 9 9 -s u i t e a n d c o r r e l a t i o n has b e e n b a s e d on l i t h o l o g i c s i m i l a r i t y ( E a s t w o o d , 1 9 6 2 , p p . 1 1 1 - 1 2 2 ) . The l o w e r p a r t o f t h e K e n n e d y L a k e s e q u e n c e c o n s i s t s o f K a r m u t s e n - 1 i k e v o l c a n i c r o c k s . T h e s e a r e c o n f o r m a b l y o v e r l a i n b y Q u a t s i n o ( ? ) . f o r m a t i o n c o n s i s t i n g o f a l o w e r , b e d d e d l i m e s t o n e member , a m i d d l e c a l c a r e o u s t u f f member , a n d a n u p p e r m a s s i v e l i m e s t o n e m e m b e r . B o n a n z a - l i k e t u f f s o v e r l i e t h e s e r o c k s w i t h a p p a r e n t c o n f o r m i t y ( E a s t w o o d , 1 9 6 2 , p . 1 1 3 ) . E a s t w o o d has s h o w n t h a t a t l e a s t t h e u p p e r p o r t i o n o f t h e K e n n e d y L a k e s e q u e n c e o c c u r s w i t h i n two m a j o r s y n c l i n e s . The e a s t e r n m o s t o f t h e s e , r e f e r r e d t o a s t h e m i n e b e l t , s t r i k e s n o r t h e a s t f r o m t h e B r y n n o r o p e n p i t . The s t r u c t u r e i s d e f i n e d by t h e c o n t a c t b e t w e e n t h e u p p e r l i m e s t o n e member a n d t h e i n t e r m e d i a t e t u f f member o f t h e Q u a t s i n o ( ? ) f o r m a t i o n . T h i s s y n c l i n e p l u n g e s n o r t h e a s t away f r o m t h e m i n e . The s t r u c t u r e i s a m i l e w i d e i n t h e m i n e a r e a a n d ha s a m i n i m u m l e n g t h o f 3 i m i l e s . I t i s e n c l o s e d by d i o r i t e a n d g r a n o d i o r i t e . The u p p e r l i m e s t o n e member o f t h e B o n a n z a ( ? ) g r o u p , a b o u t 300 f e e t t h i c k , i s s e l d o m b e d d e d t h o u g h i n t h e p i t a l t e r n a t i n g l i g h t and d a r k b a n d i n g i s common. T h i s b a n d i n g i s n o t c o n s i s t e n t i n a t t i t u d e a n d may a c t u a l l y be f l o w b a n d i n g o r a s e g r e g a t i o n o f i m p u r i t i e s i n l i m e s t o n e c a u s e d by r e c r y s t a l l i z -a t i o n . A n a v e r a g e o f f o u r a n a l y s e s o f s a m p l e s f r o m t h i s u n i t , - 2 0 0 -o b t a i n e d from company f i l e s , was 86 .5% c a l c i u m c a r b o n a t e (Table 11+). The a n a l y s e s a l s o average 3 .9% MgO but some of the samples may have been co n t a m i n a t e d by s e r p e n t i n e . Magnesian metasomatism of t h i s type i s common i n l i m e s t o n e around t h e o r e b o d i e s . The t u f f a c e o u s sequence s e p a r a t i n g the upper and lower members of t h e Q u a t s i n o ( ? ) f o r m a t i o n i s about 800 f e e t t h i c k on t h e s l o p e s of Salmonberry M o u n t a i n (Eastwood, 1 9 6 2 , pp.111).). I t i s c h a r a c t e r i s t i c a l l y w e l l - b a n d e d and g e n e r a l l y c a l c a r e o u s . The bands are w h i t i s h or p a l e p a s t e l - c o l o u r e d and are from one t o t h r e e i n c h e s t h i c k . I n the Brynnor p i t (Map 6 , i n p o c k e t ) , t h i s t u f f i s e x t r e m e l y f i n e - g r a i n e d ; bedding i s w e l l d e f i n e d h i g h up on t h e southwest w a l l but becomes i n c r e a s i n g l y i n d i s t i n c t as t h e o r e zone i s approached. An exposure o f t u f f near R e d f o r d Creek e a s t of t h e mine showed graded bedding; a n g u l a r fragments o f w h i t e f e l d s p a r were d i s -t i n g u i s h e d i n the l o w e r , c o a r s e r p o r t i o n o f each bed. Eastwood noted t h a t t u f f i n t h e mine a r e a i s d e c i d e d l y l e s s c a l c a r e o u s than the same ro c k elsewhere i n t h e a r e a . He a t t r i b u t e d t he change t o d e f o r m a t i o n , i n t r u s i o n , and metamorphism. The -*tuff i s a g r a n u l a r m i x t u r e of p l a g i o c l a s e and pyroxene. Dark l a y e r s c o n t a i n p r o p o r t i o n a t e l y more pyroxene; f i n e - g r a i n e d , l i g h t l a y e r s c o n t a i n more s e r i c i t e . Company f i l e s have a c h e m i c a l a n a l y s i s l a b e l l e d " t u f f " as f o l l o w s : CaCO^ 13.7%, FepCu 9.1+8%, SiOp 7 5 . 8 % , MgO t r a c e . - 2 0 1 -Dark, g r e y - g r e e n massive andes i t e , sometimes a m y g d a l o i d a l , sometimes p o r p h y r i t i c , o c c u r s i n g r a d a t i o n a l c o n t a c t w i t h t u f f on the west s i d e o f t h e p i t . S e r i c i t i z e d f e l d s p a r and green h o r n b l e n d e , the l a t t e r more or l e s s a l t e r e d to c h l o r i t e , occur t o g e t h e r i n an i n t e r l o c k i n g a g g r e g a t e . E p i d o t e , p y r r h o t i t e , and p r e h n i t e are found throughout both as s c a t t e r e d g r a i n s or t h i n v e i n l e t s . P r e h n i t e i s o f t e n accompanied by s e r i c i t e i n t h e s e v e i n l e t s . A c h e m i c a l a n a l y s i s of t h i s r o c k i s g i v e n i n T a b l e 13, No. 2 . The r e l a t i o n of t h i s a n d e s i t e to the l a y e r e d r o c k s i s not c l e a r . S i l l s and dykes of s i m i l a r c o m p o s i t i o n cut l i m e s t o n e and t u f f and i n most cases are c l e a r l y p r e - o r e ; m a g n e t i t e and s k a r n r e p l a c e t h e s e dykes and s i l l s as w e l l as the main a n d e s i t e body. From exposures i n t h e p i t , i t would seem t h a t a n d e s i t e o c c u r s between t u f f and l i m e s t o n e and c o u l d then be i n t e r p r e t e d as a f l o w or a s i l l . Deeper d r i l l i n g , however, has r e v e a l e d t h a t t h i s a n d e s i t e i s unconformable. Moreover t h i s u n i t does not appear i n t h e same s t r a t i g r a p h i c p o s i t i o n elsewhere i n the area and Eastwood c o n c l u d e d t h a t t h e a n d e s i t e body i s a s t o c k . I f so, i t c o u l d be c o r r e l a t e d w i t h greenstone dykes and s i l l s d e s c r i b e d p r e v i o u s l y . These a r e thought t o be an i n t r u s i v e phase of the o v e r l y i n g Bonanza group of v o l c a n i c r o c k s . Three o t h e r a n d e s i t e s t o c k s are' known i n the Brynnor mine a r e a ; one o c c u r s j u s t w i t h i n t h e s o u t h e a s t - 2 0 2 -c o r n e r of the p i t (Map 6) . The l a y e r e d r o c k s near Kennedy Lake have been i n t r u d e d by a l a r g e g r a n o d i o r i t e s t o c k . About s i x square m i l e s of the body have been mapped t o d a t e but the f u l l s i z e of t h e i n t r u s i o n i s not known. Eastwood (1962) has shown t h a t t h e g r e a t e r p a r t of the r o c k i s g r a n o d i o r i t e h a v i n g s h a r p i n t r u s i v e r e l a t i o n s w i t h c o u n t r y r o c k . He has a l s o d e f i n e d a s u b s i d i a r y p l u t o n i c r o c k type s u r r o u n d i n g t h e mine b e l t . T h i s r o c k i s not exposed i n t h e p i t but can be examined i n s c a t t e r e d outcrops n o r t h , west, and s o u t h o f the p i t . A specimen was chosen f o r c h e m i c a l and p e t r o g r a p h i c a n a l y s i s (see c h e m i c a l a n a l y s i s and norm, T a b l e 12, No, I4.) . I t i s a medium-grained, e q u i g r a n u l a r r o c k w h i c h , i n hand sample, appears t o be composed p r i m a r i l y of w h i t e p l a g i o c l a s e and c h l o r i t i c hornblende o r pyro x e n e . Very l i t t l e q u a r t z i s d i s c e r n i b l e i n hand sample. In t h i n s e c t i o n , however, q u a r t z i s r e a d i l y a p p a r e n t ; o r t h o c l a s e , a l i t t l e m i c r o p e r t h i t e , and p l a g i o c l a s e , a l l l a r g e l y a l t e r e d t o a d u s t y , r e d d i s h - b r o w n opaque m a t e r i a l , comprise the remainder o f t h e r o c k . A l i t t l e c h l o r i t i c h o r n b l e n d e , z i r c o n , sphene, o p a c i t e , and p r e h n i t e are the a c c e s s o r y m i n e r a l s . A p o i n t count gave the f o l l o w i n g mode; p l a g i o c l a s e (An-^) 37%, p o t a s h f e l d s p a r 27%, q u a r t z 29%, a c c e s s o r i e s 8%. The r o c k i s c l a s s i f i e d as q u a r t z monzonite. - 2 0 3 -Geology of the Brynnor mine The g e o l o g y of t h e Brynnor p i t , as i t was exposed i n June, 1962, i s shown i n Map 6 ( i n p o c k e t ) . F i g u r e 18 i s a diagrammatic c r o s s - s e c t i o n c o m p i l e d from l i m i t e d d r i l l d a t a . Three main ore zones have been r e c o g n i z e d by the company a l t h o u g h t h e s e were i m p e r f e c t l y exposed at the t i m e o f the w r i t e r ' s v i s i t . The ore appears t o f a v o u r the l i m e s t o n e - t u f f c o n t a c t but pockets and l e n s e s may be found e n t i r e l y w i t h i n one or the o t h e r r o c k t y p e . The upper p a r t of t h e n o r t h orebody has r e p l a c e d l i m e s t o n e . D r i l l i n g has shown t h a t i t plunges southwards as a r o u g h l y c i g a r - s h a p e d body t h a t c o n t i n u e s a l o n g the t u f f -l i m e s t o n e c o n t a c t at depth ( F i g . 1 8 ) . I t appears to be cut o f f t o the n o r t h by a f a u l t . The ore i s massive, f i n e - g r a i n e d m a g n e t i t e c o n t a i n i n g -green and b l u e s e r p e n t i n e a l o n g s l i p -s u r f a c e s . T h i s s e r p e n t i n e i s u s u a l l y a f r a c t i o n of an i n c h t h i c k and i s almost e n t i r e l y c o n f i n e d t o the ore zone; l i m e s t o n e on e i t h e r s i d e c o n t a i n s o n l y a few v e i n s of t h i s m i n e r a l . T h i n s e r p e n t i n e v e i n l e t s i n m a g n e t i t e s t o p a b r u p t l y a t the m a g e n t i t e -l i m e s t o n e c o n t a c t . Green s i l l s and dykes t h a t cut l i m e s t o n e near the ore zone have been almost c o m p l e t e l y r e p l a c e d by green s e r p e n t i n e and one o r two bodies of m a s s i v e s e r p e n t i n e are found i n l i m e s t o n e t o t h e n o r t h of t h i s ore zone. C o n t a c t s between - 2 0 5 -s e r p e n t i n e and l i m e s t o n e a re g e n e r a l l y sharp and l o c a l l y a one i n c h zone o f e u h e d r a l p y r i t e i s found a l o n g the c o n t a c t . V e r y l i t t l e s k a r n i s a s s o c i a t e d w i t h t h i s orebody, a common c h a r a c t e r i s t i c of mag n e t i t e d e p o s i t s developed l a r g e l y i n 1imestone. The c e n t r a l ore zone i s massive f i n e - g r a i n e d m a g n e t i t e w hich i s h e a v i l y s l i c k e n s i d e d a l o n g s h o r t , c u r v i n g f r a c t u r e s c o a t e d w i t h b l u e s e r p e n t i n e . Ore has formed a t the c o n t a c t between l i m e s t o n e and a n d e s i t e . S k a r n i s common on both s i d e s of the orebody but not i n t h e ore i t s e l f . O n l y a few f e e t o f the s o u t h zone was exposed a t t h e time of t h e w r i t e r ' s v i s i t . S t r u c t u r a l r e l a t i o n s were not c l e a r but i t appears t h a t o re o c c u r s a l o n g t h e t u f f - l i m e s t o n e c o n t a c t . M a g n e t i t e here i s a l s o a s s o c i a t e d w i t h s e r p e n t i n e , much of which i s y e l l o w or y e l l o w - g r e e n . J o i n t s w i t h i n l i m e s t o n e near ore a r e f i l l e d w i t h s e r p e n t i n e and i t extends out on e i t h e r s i d e of the j o i n t s f o r a q u a r t e r i n c h or more. The r o c k i n the v i c i n i t y of t h i s orebody i s cut by s e v e r a l f a u l t s and sh e a r zones, many of w h i c h c o n t a i n i r r e g u l a r l e n s e s o f m a g n e t i t e . Deep d r i l l i n g has i n d i c a t e d t h a t t h e s o u t h and c e n t r a l o r e zones may j o i n a t depth. -206-S e v e r a l ages and types of dykes are found i n t h e p i t . A few dykes a r e p r e - o r e , l a r g e l y a l t e r e d to s e r p e n t i n e . Next i n age a r e s m a l l , l i g h t t o dark g r e e n , b a s i c dykes w h i c h l o c a l l y may be s l i g h t l y s e r p e n t i n i z e d . One or two of these are rimmed w i t h a t h i n s k a r n zone where t h e y cut l i m e s t o n e ( P l a t e V I I ) . T h e i r r e l a t i o n t o ore i s unknown. A t h i r d dyke swarm i s by f a r t h e most common. These a r e l a r g e , l e u c o d i o r i t e dykes up t o 30 f e e t i n w i d t h , which v a r y s l i g h t l y i n m i n e r a l c o m p o s i t i o n . They a r e composed p r i m a r i l y o f p l a g i o c l a s e and u r a l i t i z e d a u g i t e ; t h e p r o p o r t i o n of f e l d s p a r to pyroxene v a r i e s from dyke t o dyke, or even w i t h i n a s i n g l e dyke, and e i t h e r m i n e r a l may o c c u r as s c a t t e r e d p h e n o c r y s t s . These v a r i a t i o n s i n c o m p o s i t i o n and t e x t u r e have r e s u l t e d i n a number of s l i g h t l y d i f f e r e n t r o c k types w h i c h have been grouped t o g e t h e r under t h e term " l e u c o d i o r i t e " because of t h e i r g e n e r a l d i o r i t i c c o m p o s i t i o n , l i g h t c o l o u r , and age r e l a t i v e to o r e . These dykes c u t the ore and the l a r g e r dykes may show c h i l l e d b o r d e r s a g a i n s t s k a r n and n e i t h e r s k a r n nor m a g n e t i t e i s developed i n them. These dykes a r e l a t e r t h a n the green b a s i c dykes mentioned above. A f o u r t h type of dyke r o c k , o f w h i c h o n l y one was seen, i s a t y p i c a l d i a b a s e . I t i s not i n c o n t a c t w i t h any of t h e o t h e r dykes or the o r e but i s u n a l t e r e d and may be assumed to be younger t h a n o t h e r d y k e s . - 2 0 7 -P o s t - o r e f a u l t s of g e n e r a l l y s m a l l d i s p l a c e m e n t are common. A deep-seated orebody has been o u t l i n e d by magnetometer and d r i l l i n g t o the s o u t h e a s t o f t h e p i t . T h i s body appears t o have formed a l o n g the 1 i m e s t o n e - a n d e s i t e c o n t a c t i n a down-f a u l t e d b l o c k a l o n g a f a u l t exposed i n t h e extreme s o u t h e a s t c o r n e r of the p i t . D i p - s l i p movement a l o n g t h i s f a u l t would be of the order o f 200 f e e t . Some movement a l o n g f a u l t s i n t h e p i t may be caused by d y n a m i t i n g . A f t e r one b l a s t i n t h e Brynnor p i t , a l a r g e p a r t of the 300 l e v e l moved two f e e t v e r t i c a l l y and t h r e e f e e t to the s o u t h . T h i s movement was c o n f i r m e d by s u r v e y i n g a s t a t i o n on the " f a u l t b l o c k " b e f o r e and a f t e r the e x p l o s i o n . S e l e c t e d b i b l i o g r a p h y Eastwood,G.E.P, - Geology o f t h e Kennedy Lake area - B.C. Dept. of Mines and P e t r o l . Resources Ann. Rept. 1962, 1962 111-121+. and M e r r e t t , J . E. - Kennedy Lake - B.C. Dept. of 1961 Mines and P e t r o l . Resources Ann. Rept. 1961, 101+-110. McKechnie,N.D. and M e r r e t t , J . E . - Kennedy Lake i r o n - B.C. Dept. I960 of Mines and P e t r o l . Resources Ann. Rept. 1 0 « - 1 1 0 . Roberts on,W.F. - Maggie Lake - B.C. Dept. of Mines Ann. Rept. 1902 1902, H210. - 2 0 8 -5» Nimpkish I r o n Mines L i m i t e d The mine o f f i c e and camp are on Anutz Lake, l\ m i l e s s o u t h o f Nim p k i s h Lake i n n o r t h - c e n t r a l Vancouver I s l a n d ( F i g . l ) The open p i t i s on the southwest bank of Ni m p k i s h R i v e r f i v e m i l e s s o u t h of Anutz Lake. Access t o the camp i s v i a a l i m i t e d -a ccess lumber company road from Beaver Cove. M a g n e t i t e was d i s c o v e r e d i n t h i s area i n 1897. T h i r t e e n years l a t e r Lindeman d e s c r i b e d the d e p o s i t and p r e -sented t h e r e s u l t s of a d i p - n e e d l e s u r v e y c o n d u c t e d o v e r t h e m a g n e t i t e showings (Lindeman, 1 9 1 0 ,pp. 1 9 - 2 0 ). C l a i m s c o v e r i n g the d e p o s i t were o p t i o n e d by A.H. Upton about 1951+ and l i m i t e d diamond d r i l l i n g was done a t t h a t t i m e . In t h e f o l l o w i n g y e a r , the p r o p e r t y was o p t i o n e d by Nimpkish I r o n Mines L i m i t e d , a company j o i n t l y owned by S t a n d a r d S l a g Company and I n t e r n a t i o n a l I r o n Mines L i m i t e d . No a c t i v i t y was r e p o r t e d d u r i n g the years 1957-58 but i n 1959 c o n s t r u c t i o n began on m i l l and d o c k ' f a c T t i t i M a g n e t i t e c o n c e n t r a t e p r o d u c t i o n began t h a t y e a r and by 1962 1 , 0 7 7 , 3 0 3 s h o r t tons had been s h i p p e d . L o c a l g e o l o g y The I r o n Crown (K l a a n c h ) d e p o s i t i s a l o n g the c o n t a c t of Q u a t s i n o l i m e s t o n e and Karmutsen v o l c a n i c r o c k s a d j a c e n t t o a p l u t o n i c body. T h i s p l u t o n i s p a r t of a complex r e f e r r e d t o by H o a d l e y ( 1 9 5 3 ,p.2 9 ) as the "Nimpkish i n t r u s i o n s " . -209-Karmutsen v o l c a n i c r o c k s . i n t h e mine a r e a a r e f i n e - g r a i n e d m a s s i v e , b l a c k or dark g r e e n , a n y g d a l o i d a l a n d e s i t e s . In t h i n s e c t i o n , the r o c k has a d i s t i n c t o p h i t i c t e x t u r e ; i n t e r s t i c e s between p l a g i o c l a s e l a t h s (An ) a r e f i l l e d w i t h b i o t i t e and 79 h o r n b l e n d e . Where the r o c k i s a l t e r e d , s e r i c i t e , c a l c i t e , and a c t i n o l i t e a r e common c o n s t i t u e n t s . Amygdules a r e f i l l e d w i t h e p i d o t e , c a l c i t e , or a c t i n o l i t e . P y r i t e and p y r r h o t i t e are s c a t t e r e d t h r o u g h o u t as round c l u s t e r s . P i n k l a u m o n t i t e and w h i t e c a l c i t e v e i n s t r a n s e c t the r o c k i n s e v e r a l o u t c r o p s . An a n a l y s i s of a t y p i c a l f r e s h specimen of t h i s a n d e s i t e i s g i v e n i n T a b l e 13, No. 1+. Q u a t s i n o l i m e s t o n e i n t h i s a r e a i s w h i t e or l i g h t grey and g e n e r a l l y c o a r s e l y c r y s t a l l i n e . Bedding i s r a r e or a b s e n t ; t h i n d i s c o n t i n u o u s dark bands were noted i n t h e main h e a d w a l l of t h e p i t . These may be s h a l y l a y e r s and as such would con-s t i t u t e b e d d i ng. On the o t h e r hand t h e y may be f l o w banding i n w h i c h case t h e y would not n e c e s s a r i l y bear any r e l a t i o n t o b e d d i n g . On t h e s o u t h w a l l these bands are u n d u l a t o r y but e s s e n t i a l l y h o r i z o n t a l e xcept a d j a c e n t t o the ore zone where th e y a r e v e r t i c a l , p a r a l l e l t o t h e o r e c o n t a c t . The r o c k appears to be v e r y pure c a l c i u m c a r b o n a t e , A s t a i n t e s t on one o r two specimens showed no d o l o m i t e . Q u a r t z monzonite o u t c r o p s e x t e n s i v e l y s o u t h of the p i t a l o n g t h e banks o f N i m p k i s h R i v e r . T h i s r o c k i s l e u c o c r a t i c , -210-c o a r s e - g r a i n e d , and h y p i d i o m o r p h i c . P l a g i o c l a s e , p o t a s h f e l d s p a r , q u a r t z , b i o t i t e , and h o r n b l e n d s a r e c l e a r l y v i s i b l e i n hand specimen. A p o i n t count gave t h e f o l l o w i n g mode: q u a r t z 35"%, p l a g i o c l a s e (An^g) 20%, potash f e l d s p a r ( o r t h o c l a s e and m i c r o p e r t h i t e ) 1)4.%, h o r n b l e n d e and b i o t i t e 29%, a c c e s s o r i e s 2%. A c h e m i c a l a n a l y s i s o f a t y p i c a l specimen i s g i v e n i n T a b l e 12, No. 6 . W i t h i n and a d j a c e n t t o the ore zone medium-grained g r a n u l a r d i o r i t e o c c u r s i n t e r m i x e d w i t h l a r g e and s m a l l b l o c k s of Karmutsen a n d e s i t e . S l i g h t l y s e r i c i t i z e d p l a g i o c l a s e ( A n ^ ^ ) , h o r n b l e n d e , a u g i t e , and o r t h o c l a s e are t h e main c o n s t i t u e n t s of t h i s d i o r i t e . A l o n g the s o u t h and east w a l l o f t h e p i t (Map 8 , i n p o c k e t ) , a s s i m i l a t i o n of v o l c a n i c r o c k i s so i n t e n s e t h a t i t i s d i f f i c u l t t o d i s t i n g u i s h p l u t o n i c from v o l c a n i c r o c k . A n d e s i t e has been so r e c r y s t a l l i z e d and "soaked" by t h e i n t r u s i v e r o c k t h a t i n t h e t r a n s i t i o n zone t h e d i s t i n c t i o n between f i n e - g r a i n e d d i o r i t e and c o a r s e - g r a i n e d a n d e s i t e i s a r b i t r a r y . S k a r n o c c u r s t h r o u g h o u t t h i s zone and r e p l a c e s a l l o t h e r s i l i c a t e r o c k s . J e f f e r y ( 1 9 b 0,p . l 0 2 ) has i n t e r p r e t e d t h i s d i o r i t e as b e i n g a s e p a r a t e s m a l l i n t r u s i v e body. The p r e s e n t a u t h o r , however, c o n s i d e r s i t as a co n t a m i n a t e d border phase'of t h e q u a r t z monzonite body f o r t h e f o l l o w i n g reasons: (1) d i o r i t e i s more f i n e - g r a i n e d than q u a r t z monzonite and may r e p r e s e n t a c h i l l e d phase o f the l a t t e r (2) the " b l u r r e d " -211-r e l a t i o n o f d i o r i t e w i t h a n d e s i t e and the appearance o f " s o a k i n g " of t h e l a t t e r by i n t r u s i v e r o c k . T h i s suggests t h a t the d i o r i t e m a t r i x i s a r e s u l t o f c o n t a m i n a t i o n by c o u n t r y r o c k of a magma. The b l u r r e d edges of a n d e s i t e fragments are evi d e n c e of a s s i m i l a t i o n (3) r o c k i n t h e t r a n s i t i o n zone t r a c e d away from ore toward t h e q u a r t z monzonite body, approaches t h e c o m p o s i t i o n and g r a i n s i z e o f q u a r t z m onzonite. The t r a n s i t i o n t o or c o n t a c t w i t h (depending on which t h e o r y i s f a v o u r e d ) the main q u a r t z monzonite body cannot be observ e d because the c r i t i c a l a r e a i s co v e r e d by mine roads and dumps. S e v e r a l other t y p e s o f i n t r u s i v e r o c k are exposed i n t h e p i t . A common type i s l i g h t green f e l d s p a r p o r p h y r y o c c u r r i n g as i s o l a t e d b o d i e s , g e n e r a l l y bounded by f a u l t s . These b o d i e s , as exposed i n each bench f a c e , appear d y k e - l i k e i n form but i n most cases a r e not c o n t i n u o u s from l e v e l t o l e v e l (see Map 8 i n p o c k e t ) . As t h i s r o c k - i s not exposed i n c o n t a c t w i t h ore i t s age r e l a t i v e t o the d e p o s i t c o u l d not be e s t a b l i s h e d . However, these b o d i e s a r e not r e p l a c e d anywhere i n t h e p i t by m a g n e t i t e or s k a r n and t h e c o n c l u s i o n i s t h a t t h i s r o c k i s a r e p e t i t i v e l y f a u l t e d p o s t - o r e dyke or dykes. I n t h i n s e c t i o n , a groundmass of c h l o r i t e and s e r i c i t i z e d p l a g i o c l a s e l a t h s s u r r o u n d s e r i c i t i z e d p l a g i o c l a s e p h e n o c r y s t s . C a l c i t e , e p i d o t e , and o p a c i t e a r e a c c e s s o r y m i n e r a l s . -212-One l i g h t - c o l o u r e d d y k e , a p p a r e n t l y p o s t - o r e , o c c u r s i n t h e n o r t h p a r t o f t h e p i t . I n t h i n s e c t i o n , q u a r t z a n d o r t h o c l a s e a r e s e e n t o be t h e m a i n c o n s t i t u e n t s ; p l a g i o c l a s e a n d o p a c i t e f o r m o n l y a b o u t 20% o f t h e r o c k . T e c h n i c a l l y t h e r o c k s h o u l d be c l a s s i f i e d a s a n a p l i t e a l t h o u g h i n h a n d s p e c i m e n i t l a c k s t h e t y p i c a l " s u g a r y " t e x t u r e . F e l s i t e f o r m s a n i s o l a t e d b o d y i n l i m e s t o n e , i t s m a r g i n s r e p l a c e d b y m a g n e t i t e a n d s k a r n . I n t h i n s e c t i o n , r e p l a c e m e n t b y c a l c i t e , c 1 i n o z o i s i t e , a n d s e r i c i t e ha s l a r g e l y o b l i t e r a t e d t h e o r i g i n a l c o n s t i t u e n t s b u t w h e r e a l t e r a t i o n i s l e s s i n t e n s e , i n t e r l o c k i n g p l a g i o c l a s e l a t h s f o r m t h e m a i n a g g r e g a t e . The r o c k may be a h i g h l y a l t e r e d r e m n a n t o f a n d e s i t e e m p l a c e d a s a n i n t r u s i v e p h a s e o f t h e o v e r l y i n g B o n a n z a p y r o c l a s t i c r o c k s . S m a l l d y k e s a n d s i l l s o f s i m i l a r r o c k , a l s o r e p l a c e d b y s k a r n a n d m a g n e t i t e , o c c u r t h r o u g h o u t t h e p i t b u t a r e m o s t p r o m i n e n t i n l i m e s t o n e . Two o f t h e s e f e l s i t e d y k e s , one o f w h i c h i s s h o w n i n t h e e x t r e m e s o u t h w e s t c o r n e r o f Map 8 , h a v e b e e n d e f o r m e d i n t o b o u d i n s and t h e s e g m e n t s s e p a r a t e d b y as much as t e n f e e t . I n b o t h d y k e s , a t h i n o u t e r r i m o f g a r n e t -e p i d o t e s k a r n , o c c u r r i n g i n t h e d y k e a d j a c e n t t o l i m e s t o n e , c o n t i n u e s a r o u n d t h e b r o k e n ends o f t h e d y k e a s t h o u g h m e t a s o m a t i s m h a d o c c u r r e d a f t e r t h e d y k e s had b e e n s e g m e n t e d a n d n o t when t h e d y k e s w e r e e m p l a c e d . S i m i l a r r e l a t i o n s w e r e n o t e d i n t h e K i n g f i s h e r d e p o s i t . - 2 1 3 -Geology of t h e I r o n Crown (K l a a n c h ) mine M a g n e t i t e o c c u r s as a t a b u l a r body between a n d e s i t e and c r y s t a l l i n e l i m e s t o n e . The c o n t a c t w i t h v o l c a n i c r o c k i s d i f f u s e and o b s c u r e d by s k a r n . The l i m e s t o n e c o n t a c t , i n c o n t r a s t , i s s h a r p and f r e e of c a l c - s I 1 i c a t e m i n e r a l s . W i t h i n the d e p o s i t , t h e ore i s r e l a t i v e l y pure m a g n e t i t e c o n t a i n i n g l i t t l e s k a r n or o t h e r s i l i c a t e i m p u r i t i e s . Coarse w h i t e c a l c i t e i s found t h r o u g h o u t the o r e zone as i r r e g u l a r v e i n s or pods w h i c h a r e r a r e l y found o u t s i d e t h e m i n e r a l i z e d a r e a . These "pods" f r e q u e n t l y i n c r e a s e i n number toward the l i m e s t o n e s i d e of t h e d e p o s i t and l o c a l l y c o n s t i t u t e as much as 5>0 p e r c e n t o f the o r e . C h a l c o p y r i t e , p y r i t e , and minor amounts of s p h a l e r i t e are a l m o s t e n t i r e l y r e s t r i c t e d t o t h e s e c a l c i t e b o d i e s . In many i n s t a n c e s , c a l c i t e h e a l s f r a c t u r e s i n massive ore and t h i n v e i n l e t s of c a l c i t e c u t a c r o s s l a r g e s i n g l e c r y s t a l s of m a g n e t i t e . S u l p h i d e s , so c l o s e l y a s s o c i a t e d w i t h t h i s p o s t - o r e c a l c i t e , are c o n s i d e r e d t o be p o s t - o r e even though no s u l p h i d e m i n e r a l was o b s e r v e d c u t t i n g m a g n e t i t e . S m a l l bodies of m a g n e t i t e a r e found i n l i m e s t o n e i n the west and s o u t h ends o f t h e p i t and are not v i s i b l y connected w i t h the main ore zone a l t h o u g h t h e y presumably formed at the same t i m e . -211+-In the s o u t h e a s t c o r n e r o f the p i t , the ore zone narrows and c l o s e l y f o l l o w s t h e a n d e s i t e - 1 i m e s t o n e c o n t a c t ( P l a t e I X ) . At t h i s p l a c e the c o n t a c t i s p r a c t i c a 1 l y v e r t i c a l except f o r a s m a l l p a r t , j u s t south of t h e r o a d , where i t i s f o l d e d back on i t s e l f . T h i s s l i g h t o v e r t u r n i n g p o s s i b l y was caused by f o r c e f u l i n t r u s i o n o f the q u a r t z monzonite body east of t h e p i t . The lower l i m b of t h i s " f o l d " f l a t t e n s i n d i p j u s t b e f o r e i t reaches t h e p i t f l o o r under th e south w a l l . T h i s c o u l d account f o r an apparent l o c a l i n c r e a s e i n w i d t h of the ore zone. One or two major f a u l t s s e p a r a t e the ore d e p o s i t i n t o t h r e e s e p a r a t e b o d i e s . The most prominent f a u l t s t r i k e s n o r t h -e a s t t h r o u g h the s o u t h end o f t h e p i t . I t i s exposed i n s e v e r a l f a c e s and i s marked by a b r e c c i a zone t h r e e t o f i v e f e e t w i d e . Fragments of s l i c k e n s i d e d ore and c o u n t r y r o c k are surrounded by abundant c h l o r i t e and gouge. Hematite c o a t s some of the s l i p s u r f a c e s . The f a u l t d i p s s t e e p l y s o u t h e a s t ; s t r i k e - s l i p component o f t h e o r e zone i s about 200 f e e t d e x t r a l . A r e v e r s e d i p - s l i p component o f about 100 f e e t i s i n d i c a t e d by the d i f f e r e n c e i n w i d t h o f the ore zone between t h e r o a d and the main p i t f l o o r . . Another p o s t - o r e f a u l t was not observed but i s i n f e r r e d In t h e northwest c o r n e r of t h e p i t t o account f o r t h e a b r u p t e a s t e r n t e r m i n a t i o n o f t h i s orebody (see Map 8 ) . - 2 1 5 -M o s t c o n t a c t s b e t w e e n m a j o r r o c k u n i t s a r e s l i p s u r f a c e s . A l t h o u g h some movement h a s t a k e n p l a c e a l o n g t h e s e p l a n e s t h e d i s p l a c e m e n t a p p e a r s t o be s m a l l . S e l e c t e d b i b l i o g r a p h y B a c o n , W . R . - K l a a n c h - B . C . D e p t . o f M i n e s A n n . R e p t . 1 9 5 6 , 1956 1 3 3 - 1 3 5 . E a s t w o o d , G . E . P a n d M e r r e t t , J . E . - N i m p k i s h L a k e - B . C . D e p t . 1961 o f M i n e s a n d P e t r o l . R e s o u r c e s A n n . R e p t . 1 9 6 1 , 9 3 - 9 ! i . G u n n i n g , H . C . - P r e l i m i n a r y r e p o r t o n t h e N i m p k i s h L a k e 1931 Q u a d r a n g l e , V a n c o u v e r I s l a n d , B r i t i s h C o l u m b i a -G e o l . S u r v . , C a n a d a , S u m . R e p t . 1 9 3 1 , p t . A , 2 2 - 3 5 . - P r e l i m i n a r y g e o l o g i c a l m a p , N i m p k i s h , Wes t h a l f , 1938 B r i t i s h C o l u m b i a - G e o l . S u r v . , C a n a d a , P a p e r 3 8 - 3 H o a d l e y , J . W . - G e o l o g y a n d m i n e r a l d e p o s i t s o f t h e Z e b a l l o s -1953 N i m p k i s h a r e a , V a n c o u v e r I s l a n d , B r i t i s h C o l u m b i a -G e o l . S u r v . , C a n a d a , Mem. 2 7 2 . J e f f e r y , W . G . - N i m p k i s h L a k e - B . C . D e p t . o f M i n e s a n d P e t r o l . I 9 6 0 R e s o u r c e s A n n . R e p t . I960, 1 0 1 - 1 0 3 . L i n d e m a n , E . - I r o n o r e d e p o s i t s o f V a n c o u v e r a n d T e x a d a I s l a n d s , 1910 B r i t i s h C o l u m b i a - C a n a d a , D e p t . o f M i n e s , M i n e s B r a n c h , 1 9 - 2 0 . a n d B o l t o n , L . L . - I r o n o r e o c c u r r e n c e s i n C a n a d a . I917 V o l . 1 1 D e s c r i p t i o n o f i r o n o r e o c c u r r e n c e s -C a n a d a , D e p t . o f M i n e s , N o . 2 1 7 , 11+-15. - 2 1 6 -6 . Z e b a l l o s I r o n Mines L i m i t e d The d e p o s i t s l i e a t an average e l e v a t i o n o f 2^00 f e e t on the n o r t h w e s t s l o p e o f t h e Z e b a l l o s R i v e r v a l l e y , west c o a s t of Vancouver I s l a n d ( F i g . 1 ) . A f i v e - m i l e g r a v e l r o a d l e a d s from Z e b a l l o s t o the mine o f f i c e and m i l l , the l a t t e r c o n s t r u c t e d at lj.00 f e e t e l e v a t i o n j u s t above t h e v a l l e y f l o o r . Three m i l e s of s w i t c h b a c k road connect t h e s e b u i l d i n g s w i t h t h e main bench of the open p i t a t 2I4.OO f e e t . M i n i n g a c t i v i t y i n t h i s a rea dates back t o 1907 when s m a l l amounts of p l a c e r g o l d were o b t a i n e d from Z e b a l l o s R i v e r . A minor g o l d r u s h began i n I92I4. f o l l o w i n g d i s c o v e r y of lode g o l d on t h e Tagore p r o p e r t y and i t i s l i k e l y t h a t m a g n e t i t e d e p o s i t s near B l a c k s a n d Creek were d i s c o v e r e d about t h a t t i m e . I f s o , however, t h e y d i d not r e c e i v e much a t t e n t i o n d u r i n g the s e a r c h f o r g o l d and a r e not mentioned by Young and Uglow (1926) i n t h e i r s u r v e y of i r o n ore d e p o s i t s i n w e s t e r n Canada. Claims a d j a c e n t t o t h e F.L. (Ford) d e p o s i t were s t a k e d i n 1937-38 and the F.L. c l a i m was p r o b a b l y s t a k e d about t h a t time a l s o . In 1951, the p r o p e r t y was c o n t r o l l e d by Anyox M e t a l s L i m i t e d , a s u b s i d i a r y of Ventures L i m i t e d . T h i s company c a r r i e d out a s y s t e m a t i c e x p l o r a t i o n program i n c l u d i n g g e o l o g i c mapping, a d i p - n e e d l e s u r v e y , and diamond d r i 1 1 i n g . D u r i n g 1959-60, Z e b a l l o s I r o n Mines L i m i t e d , a s u b s i d i a r y of I n t e r n a t i o n a l I r o n - 2 1 7 -Mines L i m i t e d , t o o k over t h e p r o p e r t y and c o n t i n u e d d r i l l i n g i n the main ore zone. P r o d u c t i o n began i n the summer of 1962 and 2 ^ 0 , 2 9 7 s h o r t tons of m a g n e t i t e c o n c e n t r a t e were s h i p p e d t h a t y e a r . O p e r a t i o n s ceased i n the s p r i n g of 1963 due t o f i n a n c i a l d i f f i c u l t i e s . L o c a l g e o l o g y R e g i o n a l geology o f t h e Z e b a l l o s area has been d e s c r i b e d by S t e v e n s o n , (1950) and Hoa d l e y ( 1 9 5 3 ) * The geology of t h e F.L. d e p o s i t was d i s c u s s e d by Bacon ( 1 9 5 2 ) , McKechnie ( I 9 6 0 ) , and Eastwood and M e r r e t t ( 1 9 6 2 ) . The main ore zone, the F.L. or Ford d e p o s i t , l i e s a l o n g t h e c o n t a c t between Q u a t s i n o l i m e s t o n e and h i g h l y a l t e r e d Bonanza group v o l c a n i c rocks ( F i g . 1 9 ) . Limestone occurs a l o n g the a x i a l t r a c e o f a s o u t h w e s t e r l y - p l u n g i n g a n t i c l i m e which i s a p p r o x i m a t e l y a t r i g h t a n g l e s t o t h e g e n e r a l n o r t h w e s t e r l y t r e n d o f t h e r e g i o n a l s t r u c t u r e . T h i s c r o s s f o l d i s p r e s e r v e d as an e l o n g a t e l o b e , 1^ - m i l e s l o n g , surrounded on t h r e e s i d e s by t h e Z e b a l l o s b a t h o l i t h ( Hoadley, 1 9 5 3 ,Pp. 6 6 - 6 8 ) . Q u a t s i n o l i m e s t o n e i n t h i s a rea has been l a r g e l y r e c r y s t a l 1 i z e d and bedding o b l i t e r a t e d over l a r g e areas a l t h o u g h i t i s d i s t i n c t enough i n s e v e r a l o u t c r o p s to d e f i n e l o c a l s t r u c t u r e s . W e a t h e r i n g i s u s u a l l y g r e y or g r e y - w h i t e i n c o l o u r . - 2 1 9 -A n a l y s e s of l i m e s t o n e samples c o l l e c t e d from about the same h o r i z o n ( i . e . the t o p of the f o r m a t i o n ) on the o p p o s i t e s i d e o f the Z e b a l l o s R i v e r have been p r e s e n t e d by S t e v e n s o n (195"0,p. 1 8 ) . S i x samples showed the f o l l o w i n g range i n c o m p o s i t i o n : MgO 1 9 . 6 - 0 . 3 7 % , CaO 5^.14.-32.7%, R 2 0 3 0.76-05%, I n s o l . 5 . 1 8 - 0 . 8 8 % . Stevenson c o n s i d e r e d t h a t much of t h e magnesium content o f t h e s e samples was caused by d o l o m i t i z a t i o n of l i m e s t o n e a d j a c e n t of g r a n i t i c i n t r u s i o n s . The o r i g i n a l n a t u r e of the o v e r l y i n g Bonanza group i rocks has been more or l e s s o b s c u r e d by v a r i o u s types o f a l t e r a t i o n c a u s e d , i n l a r g e p a r t , by the nearby Z e b a l l o s b a t h o l i t h . Near the south end o f t h e ore zone, v o l c a n i c rocks are i n t r u d e d by a p l i t i c and d i o r i t i c dykes and I r r e g u l a r bodies over a wide zone which s e p a r a t e s the Z e b a l l o s i n t r u s i o n from the orebody. To the n o r t h , a l o n g the n o r t h l i m b of the a n t i c l i n e , t h i s zone becomes l e s s d i s t i n c t and f i n a l l y d i s a p p e a r s . G e n e r a l l y , the Bonanza r o c k s a r e m a s s i v e , d a r k green and f i n e -g r a i n e d . Bedding was not o b s e r v e d by the w r i t e r anywhere i n the mine area a l t h o u g h Eastwood has d e s c r i b e d the rocks as t u f f , i n p a r t r e c r y s t a l 1 i z e d , and noted t h a t the r o c k s showed c l a s t i c t e x t u r e i n s e v e r a l l o c a l i t i e s (Eastwood and M e r r e t t , 1 9 6 2 , p . 1 0 1 ) . The p r e s e n t w r i t e r c o l l e c t e d s e v e r a l samples o f a n d e s i t e from r o c k s o f the Bonanza group near the p i t . In s e c t i o n , s c a t t e r e d p l a g i o c l a s e p h e n o c r y s t s are seen t o l i e i n an i n t e r l o c k i n g - 2 2 0 -m a t r i x of p l a g i o c l a s e l a t h s , a u g i t e , and h o r n b l e n d e . T r a c h y t i c t e x t u r e was seen i n s e v e r a l t h i n s e c t i o n s . A n d e s i t e f l o w s w i t h o r i e n t e d p l a g i o c l a s e l a t h s have been r e p o r t e d e l s e w h e r e i n t e r -bedded w i t h Bonanza t u f f s and b r e c c i a s ( Stevenson, 1 9 5 0 ,p. 2 0 ) . A c h e m i c a l a n a l y s i s of a n d e s i t e , c o l l e c t e d by the pre s e n t w r i t e r , from the F.L. d e p o s i t i s shown i n T a b l e 13, No. 3« About IL5> square m i l e s o f t h e Z e b a l l o s b a t h o l i t h a r e exposed i n the Woss Lake-Zeba 1los map-areas. The f u l l s i z e o f the b a t h o l i t h i s not known but i t has been mapped over a l e n g t h of 18 m i l e s and at the w e s t e r n edge o f the Woss Lake sheet i t i s f i v e m i l e s wide. I t i s an e l o n g a t e p l u t o n w h i c h t r e n d s n o r t h -w e s t e r l y , c u t t i n g a c r o s s the r e g i o n a l t r e n d of the s e d i m e n t a r y rocks at a low a n g l e (Hoadley, 1 9 5 3 )• The ro c k s c o m p r i s i n g the Z e b a l l o s b a t h o l i t h a re not u n i f o r m i n c o m p o s i t i o n or appearance. Hoadley b r o a d l y c l a s s i f i e d t h e r o c k s i n the area s o u t h e a s t o f the Z e b a l l o s R i v e r as q u a r t z d i o r i t e and those on the northwest s i d e as d i o r i t e w i t h minor amounts of gabbro. In a d e t a i l e d s t u d y of t h e b a t h o l i t h i n Z e b a l l o s a r e a , Stevenson (1950) s e p a r a t e d t h e i n t r u s i o n i n t o f o u r phases. These a r e , from o l d e s t t o youngest, gabbro, h o r n b l e n d e d i o r i t e , g r a n o d i o r i t e , and q u a r t z d i o r i t e . The i n t r u s i v e r o c k a d j a c e n t t o the F.L. d e p o s i t i s shown on h i s map ( S t e v e n s o n , 1 9 5 0 , F i g . 2 ) as ho r n b l e n d e d i o r i t e . The t e x t u r e o f t h i s r o c k i s medium-grained, e q u i --221-g r a n u l a r , and h y p i d i o m o r p h i c . P l a g i o c l a s e , minor q u a r t z , and g r e e n - b l a c k hornblende combine t o g i v e the r e c k a " s a l t - a n d -pepper" appearance. Under the m i c r o s c o p e , e u h e d r a l p l a g i o c l a s e c r y s t a l s a r e abundant; o r t h o c l a s e and m i c r o p e r t h i t e occur i n t e r s t i t i a l l y as s u b h e d r a l g r a i n s . Ragged s u b h e d r a l green-brown h o r n b l e n d e g r a i n s shewing p a r t i a l a l t e r a t i o n t o brown b i o t i t e a r e s c a t t e r e d t h r o u g h o u t . C l e a r , a n h e d r a l q u a r t z , o c c u r r i n g i n c o n s i d e r a b l y g r e a t e r abundance t h a n a m a c r o s c o p i c e x a m i n a t i o n would s u g g e s t , f i l l s t h e i n t e r s t i c e s . A c c e s s o r y m i n e r a l s i n c l u d e a p a t i t e , o p a c i t e , b i o t i t e , c h l o r i t e , s e r i c i t e ( a f t e r f e l d s p a r ) , t r e m o l i t e , and a u g i t e . A p o i n t count gave the f o l l o w i n g mode: p l a g i o c l a s e ( A n ^ ) 29%, p o t a s h f e l d s p a r 28%, q u a r t z 23%, hornblende 10%, a c c e s s o r i e s 9%. On t h e b a s i s of t h i s mode t h e r o c k i s c l a s s i f i e d as q u a r t z m o nzonite. A c h e m i c a l a n a l y s i s o f t h i s r o c k i s g i v e n i n T a b l e 12, No. Geology of the F.L. (Ford) mine The s u r f a c e g e o l o g y o f t h i s d e p o s i t i s shown i n Map 7 ( i n p o c k e t ) . The ore zone i s an e s s e n t i a l l y t a b u l a r body of e x c e p t i o n a l l y pure magn e t i t e d i p p i n g about I4.O degrees west; average t r u e w i d t h i s 70 t o 80 f e e t . Company g e o l o g i s t s have a r b i t r a r i l y d i v i d e d t h e d e p o s i t i n t o two p a r t s , an 'A' and 'B' zone. -222-Throughout most o f the 'B' zone, m a g n e t i t e i s exposed i n steep b l u f f s and i n s e v e r a l p l a c e s m a s s i v e m a g n e t i t e c o u l d he seen at t h e base o f t h e s e c l i f f s r e s t i n g d i r e c t l y on w h i t e c r y s t a l l i n e l i m e s t o n e . The c o n t a c t i s v e r y sharp and has l i t t l e or no s k a r n . P y r i t e commonly occurs i n a t h i n l a y e r between magnetite and l i m e s t o n e . Here and t h e r e a l o n g t h e c o n t a c t , bedding i n l i m e s t o n e i s p r e s e r v e d r i g h t up to the m a g n e t i t e and i t c o u l d be seen t h a t t h e base of the ore zone d i p s west at an a n g l e s h a l l o w e r t h a n the d i p o f the l i m e s t o n e . T h i s s u g g e s t s t h a t m a g n e t i t e , which i n the o u t c r o p has r e p l a c e d Bonanza v c l c a n i c s down t o t h e c o n t a c t w i t h l i m e s t o n e , might l e a v e t h e l i m e s t o n e c o n t a c t as the ore i s f o l l o w e d down-dip. D r i l l i n g i n t h i s zone h a s , i n f a c t , i n d i c a t e d t h a t the l i m e s t o n e - v o l c a n i c c o n t a c t r a p i d l y steepens w i t h depth and s e v e r a l d r i l l - h o l e s i n t e r s e c t e d t h i s c o n t a c t below t h e main ore zone. As soon as i t s f o o t w a l l d i v e r g e s from the v o l c a n i c - l i m e s t o n e c o n t a c t , the ore zone d e c r e a s e s i n t h i c k n e s s and pinches out. The n o r t h h a l f o f t h e 'A' zone i s s i m i l a r t o t h e 'B ! zone; massive m a g n e t i t e i s i n sharp c o n t a c t w i t h l i m e s t o n e at the base of the ore zone ( P l a t e V I I I ) . Near th e south end of t h i s zone, however, l i m e s t o n e t u r n s t o the e a s t as i t swings around the nose of the a n t i c l i n e mentioned e a r l i e r . The t a b u l a r ore zone does not swing w i t h l i m e s t o n e but c o n t i n u e s on w i t h l i t t l e change of s t r i k e i n t o m i g m a t i t i c q u a r t z - m o n z o n i t e - 2 2 3 -and f i n a l l y p i nches out i n a m i x t u r e of s k a r n , m a g n e t i t e and mi gmat i t e . M e n t i o n has been made of the s h a r p m a g n e t i t e -l i m e s t o n e c o n t a c t exposed a t the base of the orebody. T h i s abrupt s k a r n - f r e e t e r m i n a t i o n i s i n marked c o n t r a s t t o t h e upper p a r t of the ore zone. The s t r a t i g r a p h i c a l l y h i g h e r l i m i t of ore i s determined l a r g e l y by economic c u t - o f f grades r a t h e r t h a n by any g e o l o g i c a l t e r m i n a t i o n . M a s s i v e c o a r s e - g r a i n e d m a g n e t i t e i n the lower part o f the ore zone g r a d u a l l y becomes f i n e r - g r a i n e d w i t h more admixed s k a r n and a l t e r e d m i g m a t i t e i n t h e upper p a r t . S k a r n e v e n t u a l l y d i s a p p e a r s upward as t h e upper l i m i t of the m i n e r a l i z e d zone i s approached. M a s s i v e s k a r n i s not everywhere abundant i n the F.L. d e p o s i t but l o c a l l y , such as i n t h e south h a l f of the 'A' zone, i t c o n s t i t u t e s a major p o r t i o n o f the m i n e r a l i z e d a r e a . Skarn i n t h i s d e p o s i t i s u n u s u a l because pyroxene and e p i d o t e , r a t h e r than g a r n e t , are i t s main c o n s t i t u e n t s . Large areas of the main f a c e i n t h e p i t are composed almost e n t i r e l y of m a s s i v e , g r a n u l a r green e p i d o t e . In one l o c a l i t y , a massive e p i d o t e zone i s s i x t o e i g h t f e e t t h i c k and the t r a n s i t i o n zone t h r e e f e e t t h i c k . P o s t - o r e dykes up t o f o u r f e e t wide o c c u r here and t h e r e throughout th e d e p o s i t . Two t y p e s were r e c o g n i z e d : a -22U,-l i g h t green f e l d s p a r - p o r p h y r y and hornblende l e u c o d i o r i t e . C h i l l e d b o r d ers a g a i n s t s k a r n and m a g n e t i t e were seen i n one f e l d s p a r p o r p h y r y dyke; n e i t h e r s et shows ore m i n e r a l i z a t i o n 'within i t . N e a r l y v e r t i c a l , p o s t - o r e f a u l t s of s m a l l d i s p l a c e -ment a r e common. Two of t h e more prominent of t h e s e a r e shown i n Map 6 . Both f a u l t s t r e n d s o u t h e a s t and show r i g h t hand d i s p l a c e m e n t . Geology of t h e Ridge d e p o s i t About 1700 f e e t e a s t o f the F.L. d e p o s i t , massive m a g n e t i t e i s exposed i n almost c o n t i n u o u s o u t c r o p over an a r e a of about 1^,000 square f e e t ( F i g . 19). Ore occurs between l i m e s t o n e and a medium-grained i n t r u s i o n of d i o r i t i c c o m p o s i t i o n . To the s o u t h and west a n d e s i t e o u t c r o p s are i n c o n t a c t w i t h massive m a g n e t i t e . These c o n t a c t s a r e " b l u r r y " and i l l - d e f i n e d but m a g n e t i t e unaccompanied by sk a r n appears to have r e p l a c e d a n d e s i t e . The o r e i s g e n e r a l l y medium-grained m a g n e t i t e con-t a i n i n g l i t t l e or no s k a r n or s u l p h i d e s . M a g n e t i t e c o n t a c t s w i t h l i m e s t o n e a re sharp and d i p s t e e p l y . F e l d s p a r - p o r p h y r y dykes, some showing c h i l l e d b o r d e r s a g a i n s t m a g n e t i t e , and l i g h t green f i n e - g r a i n e d p l a g i o c l a s e --225-a c t i n o l i t e dykes t r a n s e c t t h e o r e . A d i p - n e e d l e s u r v e y was c a r r i e d out w i t h t h e hope t h a t i t would a i d i n e v a l u a t i n g t h i s d e p o s i t . The r e s u l t of t h i s s u r v e y , as w i l l be d e s c r i b e d below, w i l l i l l u s t r a t e the danger of p r e d i c t i n g the ex t e n t o f such c o n t a c t metasomatic d e p o s i t s from the o u t c r o p p a t t e r n even w i t h the a i d of p r e v i o u s e x p e r i e n c e and a l i m i t e d g e o p h y s i c a l s u r v e y . The s i z e and shape of the s u r f a c e exposure o f t h e Ridge d e p o s i t i s shown i n F i g u r e 22. F i g u r e s 20 and 21 a r e t r a n s p a r e n t o v e r l a y s of t o p o g r a p h i c and d i p ne e d l e s u r v e y s , r e s p e c t i v e l y , of t h e same d e p o s i t . In e v a l u a t i n g t h i s d e p o s i t , the f o l l o w i n g g e o l o g i c f a c t o r s were n o t e d : (1) the r o u g h l y o v a l shape o f t h e o u t c r o p (2) h i g h p u r i t y o f the o r e (68% Fe, Ste v e n s o n , 1950,p.128) (3) ore i s developed almost e n t i r e l y i n l i m e s t o n e (Lj.) absence of s k a r n and s u l p h i d e s (5) s t e e p l y d i p p i n g c o n t a c t s w i t h l i m e s t o n e . Note t h a t i n many r e s p e c t s the geology of t h i s d e p o s i t resembles t h a t of the two K i n g f i s h e r d e p o s i t " p i p e s " and t h e p l u n g i n g c i g a r - s h a p e d n o r t h orebody o f Brynnor Mines L i m i t e d . A d e t a i l e d d i p - n e e d l e s u r v e y was made over t h e ore zone and some d i s t a n c e beyond. The h i g h e s t r e a d i n g s of t h i s • F I G U R E 20 ' T O P O G R A P H Y , FTIFJGE D E P O S I T , Z E B A L L O S IRON M I N E S L IM ITED. C O N T O U R I N T E R V A L - 20 F E E T Geologic contact mm _ Talus covered area Feldspar porphyry Greenstone Quartz monzonite, diorite 1 Bonanza (?) group- andesite Quatsino formation-limestanJ Massive magnetite i ro co 25 Scale in feet 50 - 2 2 9 -s u r v e y t e r m i n a t e d a b r u p t l y w i t h i n or a t t h e o u t c r o p boundary ( Fig. 2 1 ) . T h i s would support g e o l o g i c a l o b s e r v a t i o n s which suggest t h a t t h e ore c o n t a c t i s steep and t h a t m a g n e t i t e does not extend l a t e r a l l y beneath a l i m e s t o n e c o v e r . I f t h i s were the case, t h e d i p needle r e a d i n g s might be expected to decrease g r a d u a l l y away from the exposed ore zone. The d i p n e e d l e c o n t o u r s c u t a c r o s s t o p o g r a p h i c c o n t o u r s over most of the area (Fig.20 ,21 ) showing t h a t the m a g n e t i c c o n t o u r s are not a f f e c t e d by t opography. By a n a l o g y t h e n , to the K i n g f i s h e r " p i p e s " and the Brynnor " c i g a r " , the Ridge ore zone c o u l d be expected t o be of a s i m i l a r n a t u r e and p l u n g e s t e e p l y as a c y 1 i n d e r - s h a p e d depos i t . The geology i s s i m i l a r i n a l l t h r e e d e p o s i t s and d i p - n e e d l e o b s e r v a t i o n s seem to support g e o l o g i c i n t e r p r e t a t i o n s . On t h i s b a s i s and assuming o r e w i l l c o n t i n u e downward f o r 200 f e e t below the s u r f a c e , r e t a i n i n g r o u g h l y the same grade and con-f i g u r a t i o n as at the s u r f a c e , the e s t i m a t e d tonnage w o u l d be 1|.50,000 s h o r t t o n s . D r i l l i n g was done by t h e Z e b a l l o s company to t e s t t h i s t h e o r y . V e r t i c a l d r i l l h o l e s d i r e c t e d t h rough the d e p o s i t , however, passed i n t o c r y s t a l l i n e l i m e s t o n e a t an average depth of 2 0 f e e t . Lengthy i n c l i n e d h o l e s , c o l l a r e d i n l i m e s t o n e at the edge o f the exposed m a g n e t i t e , passed beneath ore and remained i n l i m e s t o n e throughout t h e i r l e n g t h . There-f o r e , i n s t e a d of b e i n g a v e r t i c a l p i p e - s h a p e d d e p o s i t w i t h 2 3 0 -e x p e c t a t i o n s o f 1+50,000 tons as s u r f a c e exposures would s u g g e s t , the Ridge d e p o s i t i s a s h a l l o w , s a u c e r - s h a p e d body of about 50,000 t o n s . S e l e c t e d b i b l i o g r a p h y B a n c r o f t , M . F . - Z e b a l l o s m i n i n g d i s t r i c t and v i c i n i t y , B r i t i s h 191+0 Columbia - G e o l . S u r v . , Canada, Paper 1+0-12. Dolmage,V. - West coast of Vancouver I s l a n d between B a r k l e y 1921 and Q u a t s i n o Sounds - G e o l . S u r v . , Canada, Summ. Rept. 1921, P t . A , 1 2 - 2 2 . Eastwood,G.E.P. and. M e r r e t t , J .E. - Z e b a l l o s - B.C. Dept. o f 1962 Mines and P e t r o l . Resources Ann. Rept. 1962, 1 0 0 - 1 0 3 . Gunning,H.C. - Z e b a l l o s R i v e r a r e a , - Vancouver I s l a n d , B. C. -1933 G e o l . S u r v . , Canada, Summ. Rept. 1932, P t . A I I , 29=^0. Hoadley,J.W. - Z e b a l l o s , B r i t i s h Columbia - G e o l . S u r v . , Canada, 1950 P r e l i m , map 50-9A. - Geology and m i n e r a l d e p o s i t s o f the Z e b a l l o s -1953 Nimpkish a r e a , Vancouver I s l a n d , B r i t i s h Columbia -G e o l . S u r v . , Canada, Mem. 2 7 2 . McKechnie,N.D. and M e r r e t t , J . E . - Z e b a l l o s - B.C. Dept. of Mines I 9 6 0 and P e t r o l . Resources Ann. Rept'. l"9o"0, 103-101+. S t e v e n s o n , J . S . - Vancouver I s l a n d , Z e b a l l o s R i v e r s e c t i o n -1936 B.C. Dept. o f Mines Ann. Rept. 1936, F38-F1+0. - Geology and m i n e r a l d e p o s i t s of the Z e b a l l o s 1950 m i n i n g camp, B.C. - B.C. Dept. o f M i n e s , B u l l . 2 7 . and Machonachie,R.J. - The Z e b a l l o s area - B.C. 1939 Dept. o f Mines Ann. Rept. 1938, F1+1-F65. - 2 3 1 -7. Jedway I r o n Ore L i m i t e d The d e p o s i t occurs n e a r the extreme s o u t h e r n t i p of Moresby I s l a n d , the southernmost of two l a r g e i s l a n d s which comprise t h e Queen C h a r l o t t e I s l a n d s . Jedway t o w n s i t e i s l o c a t e d on t h e e a s t e r n shore of H a r r i e t Harbour i n S k i n c u t t l e I n l e t , 70 a i r m i l e s s o u t h e a s t o f S a n d s p i t . The main m a g n e t i t e d e p o s i t ( J e s s i e c l a i m ) i s found a t about 1000 f e e t e l e v a t i o n and 6000 f e e t s o u t h e a s t o f the t o w n s i t e ( F i g . l ) . M i n e r a l d e p o s i t s and o c c u r r e n c e s , m a i n l y copper-b e a r i n g , have been known i n the area s i n c e 1863• M a g n e t i t e on the J e s s i e c l a i m was f i r s t r e p o r t e d by Young and Uglow i n 1926 pp.39-1+2) a l t h o u g h m a g n e t i t e had e a r l i e r been known t o o c c u r on the west s i d e o f H a r r i e t Harbour (McConne 1 1 , 1 9 0 9 ,p.7 8). In 1959, S i l v e r S t a n d a r d Mines L i m i t e d h e l d the J e s s i e c l a i m under o p t i o n from C o n s o l i d a t e d E x p l o r a t i o n Company L i m i t e d . In t h a t y e a r , a ground magnetometer s u r v e y , d r i l l i n g , and s t r i p p i n g were c a r r i e d out on the p r o p e r t y . E x p l o r a t i o n and development c o n t i n u e d through I960 and e a r l y i n I 9 6 I the p r o p e r t y was s o l d t o Jedway I r o n Ore L i m i t e d , a s u b s i d i a r y of the Granby M i n i n g Company L i m i t e d , and c o n s t r u c t i o n of Jedway t o w n s i t e began almost i m m e d i a t e l y . P r o d u c t i o n began i n 1962 when 5"3j5l5 s h o r t tons of m a g n e t i t e c o n c e n t r a t e were s h i p p e d . - 2 3 2 -L o c a l g e o l o g y S u t h e r l a n d - B r o w n and J e f f e r y (I96O) have d i s c u s s e d the geology of the s o u t h e r n Queen C h a r l o t t e I s l a n d s . The g e o l o g i c a l s e t t i n g of the J e s s i e orebody has been b r i e f l y d e s c r i b e d by J e f f e r y (1959) and Su t h e r l a n d - B r o w n and Robinson ( 1 9 6 1 ) . F i n e - g r a i n e d , dark green o r b l a c k a m y g d a l o i d a l a n d e s i t e of t h e 'Older v o l c a n i c s ' group are t h e o l d e s t r o c k s exposed i n t h i s a r e a . These r o c k s are p r o b a b l y c o r r e l a t i v e w i t h t h e Karmutsen group on Vancouver I s l a n d ( T a b l e 1 ) . In t h i n s e c t i o n , p l a g i o c l a s e (An^g), c h l o r i t e , and o p a c i t e are t h e main con-s t i t u e n t s of t h i s r o c k . "Cloudy" p l a g i o c l a s e occurs as sub-h e d r a l l a t h s (see d i s c u s s i o n , Appendix I I ) . C h l o r i t e . h a s p r o b a b l y formed by a l t e r a t i o n of m a f i c m i n e r a l s . M a g n e t i t e occurs l a r g e l y as c r y s t a l l i t e s , a c o n d i t i o n caused by r a p i d c o o l i n g which does not a l l o w t h e i n i t i a l c r y s t a l l i t e s s u f f i c i e n t time t o arrange themselves i n t o e u h e d r a l forms ( S c h w a r t z , 1 9 2 9 ) . M a s s i v e grey l i m e s t o n e o f t h e Kunga f o r m a t i o n c o n f o r m a b l y o v e r l i e s t h i s a n d e s i t e . In the type s e c t i o n on Kunga I s l a n d , t h i s member i s 550 f e e t t h i c k but i n t h e mine ar e a i t i s o n l y 60 f e e t t h i c k . Thin-bedded b l a c k l i m e s t o n e , c a l c a r e o u s a r g i l l i t e s , and s i l t s t o n e , a l l of t h e Kunga form-- 2 3 3 -a t i o n , l i e s t r a t i g r a p h i c a 1 l y above the massive c r y s t a l l i n e 1imestone. The Jedway s t o c k , of about 1^ - square m i l e s s u r f a c e a r e a , o u t c r o p s east and south of H a r r i e t H a rbour. The i n t r u s i v e c o n t a c t dips about LLO degrees n o r t h e a s t under the J e s s i e d e p o s i t but f u r t h e r t o t h e s o u t h e a s t , i n a t l e a s t one l o c a l i t y , I t i s e s s e n t i a l l y h o r i z o n t a l (K. F a h r n i , company g e o l o g i s t , p e r s o n a l communication)- The r o c k i s p r i n c i p a l l y h o rnblende d i o r i t e , c o n s i d e r e d t o be L a t e C r e t a c e o u s or E a r l y T e r t i a r y ( S u t h erland-Brown and Robinson,I96I,p.13). A t y p i c a l specimen c o l l e c t e d i n the mine area i s q u a r t z monzonite w i t h a mode: p l a g i o c l a s e ( A n ^ ) 33%, q u a r t z 28%, o r t h o c l a s e 25%, hornblende 13%, a c c e s s o r i e s 1%. A c h e m i c a l a n a l y s i s of t h i s r o c k i s g i v e n i n Ta b l e 12, No. 7 . R e g i o n a l mapping by o f f i c e r s o f the B.C. Department of Mines and P e t r o l e u m Resources has shown t h a t the J e s s i e d e p o s i t l i e s on the n o r t h limb of a broad a n t i c l i n e t h a t t r e n d s a p p r o x i m a t e l y w e s t - n o r t h w e s t (Sutherland-Brown and R o b i n s o n , 1 9 6 l , p . 1 3 ) . -231+-Geology of t h e J e s s i e mine S t r i p p i n g had reached o n l y the uppermost t i p o f t h i s d e p o s i t when the w r i t e r v i s i t e d the p r o p e r t y i n A u g u s t , 1962. E x p l o r a t i o n was s t i l l i n p r o g r e s s and the g e o l o g i c s e t t i n g of the orebody was not c o m p l e t e l y known at t h a t t i m e . A b r i e f d e s c r i p t i o n i s g i v e n h e r e u s i n g d a t a not o n l y from the au t h o r ' s o b s e r v a t i o n s b u t , to a l a r g e e x t e n t , from company f i l e s and c o n v e r s a t i o n s w i t h company g e o l o g i s t s . The geology i n t h e p i t i s shown i n Map 9 ( i n p o c k e t ) and F i g u r e 23 i s a v e r t i c a l s e c t i o n t h r o u g h t h e main ore zone. The d e p o s i t c o n s i s t s o f s e v e r a l t a b u l a r b o d i e s developed i n a n d e s i t e below t h e lower l i m e s t o n e member of the Kunga f o r m a t i o n . These bodies l i e about 100 f e e t below and •roughly p a r a l l e l t o t h e l i m e s t o n e c o n t a c t . They s t r i k e n o r t h w e s t and d i p 35 to 1+5* degrees n o r t h e a s t . The Jedway s t o c k i s from one t o more t h a n 1^0 f e e t below the o r e l e n s e s . F i g u r e 23 shows the massive n a t u r e o f the main ore zone; f u r t h e r t o t h e west, t h i s body d i g i t a t e s i n t o a number of o r e l e n s e s each 20 t o 60 f e e t t h i c k . C h l o r i t e i s a common m i n e r a l both i n ore and a d j a c e n t c o u n t r y r o c k . Garnet s k a r n accompanies m a g n e t i t e i n the orebody and a l s o o c c u r s as an "en v e l o p e " around the o r e zones. Most s k a r n i s p r e - o r e as shown.by c r o s s - c u t t i n g r e l a t i o n s . JEDWAY IRON ORE LTD. Jessie deposit DIAGRAMMATIC SECTION A - A ' S C A L E : - l"= 1 0 0 ' E2 J ES3 Jedway quartz monzonite Dark limestone, argilite Massive limestone } Kunga formation Older volcanic* Mam ore tone - 2 3 6 -S m a l l - s c a l e f a u l t i n g i s prominent i n the p i t . Both normal and t h r u s t f a u l t s of s m a l l d i s p l a c e m e n t are p r e s e n t . Large f a u l t s , however, do occur and one o f t h e more imp o r t a n t of t h e s e s t r i k e s northwest and d i p s s t e e p l y t o the southwest. T h i s f a u l t has c u t o f f t h e southwest end of t h e orebody ( F i g . 23) and p l u t o n i c r o c k o f t h e Jedway s t o c k has been t h r u s t up t o form t h e hanging w a l l of t h e d e p o s i t i n t h i s a r e a . S e l e c t e d b i b l i o g r a p h y J e f f e r y , W . G . - H a r r i e t Harbour - B.C. Dept. o f Mines Ann. 1959 R e p t . 1959, 11-11+ S u t h e r l a n d - B r o w n ,A . and Robins on,W.C. - H a r r i e t Harbour -1961 B.C. Dept. of Mines and P e t r o l . Resources Ann. Rept . 196T7 13-TT. and J e f f e r y , W . G . - P r e l i m i n a r y g e o l o g i c a l 1960 map of the s o u t h e r n Queen C h a r l o t t e I s l a n d s , B.C. and notes on the geology - B.C. Dept. of M i n e s . -237-Other d e p o s i t s In a d d i t i o n t o the mines d e s c r i b e d i n t h e p r e c e d i n g pages, the w r i t e r b r i e f l y v i s i t e d s e v e r a l o t h e r c o n t a c t meta-somatic d e p o s i t s . Two of these o f economic importance a r e d e s c r i b e d below. The d e s c r i p t i o n s a r e based on the w r i t e r ' s o b s e r v a t i o n s supplemented by data from the l i t e r a t u r e . 8. Coast Copper Company The C o n s o l i d a t e d M i n i n g and S m e l t i n g Company of Canada owns and mines a s m a l l c h a l c o p y r i t e - m a g n e t i t e d e p o s i t w hich l i e s two m i l e s n o r t h o f t h e Empire Development Company l i m i t e d h o l d i n g s i n n o r t h - c e n t r a l Vancouver I s l a n d ( F i g . 1 ) . The d e p o s i t was o r i g i n a l l y e x p l o i t e d f o r i t s copper c o n t e n t (about 2%) but m a g n e t i t e , r e c o v e r e d i n m i l l i n g o f copper o r e , i s now b e i n g s t o c k p i l e d pending shipment t o Japan. The d e p o s i t c o n t a i n s an average o f 15> p e r c e n t i r o n . A c o n t a c t between Karmutsen a n d e s i t i c v o l c a n i c s and Q u a t s i n o l i m e s t o n e i s r e f e r r e d t o i n t h i s a r e a as t h e "Old S p o r t " h o r i z o n . L a y e r e d rocks o f the Vancouver group form a l a r g e open s y n c l i n e w i t h d i o r i t e - g a b b r o of t h e Coast Copper s t o c k i n t r u d e d i n t o t h e nose o f t h i s s t r u c t u r e . Near t h e - 2 3 8 -Coast Copper Company mine, the i n t r u s i v e c o n t a c t d i p s about 70 degrees outward; the Old S p o r t h o r i z o n d i p s toward i t at about 35 degrees to the southwest. M i n e r a l i z a t i o n o c c u r s j u s t above the Karmutsen a n d e s i t e , between i t and an upper, t a b u l a r body o f green f i n e - g r a i n e d v o l c a n i c r o c k . T h i s green r o c k i s b e l i e v e d t o be an i n t e r b e d d e d l a v a f l o w i n t h e Q u a t s i n o f o r m a t i o n (Eastwood and M e r r e t t , I 9 6 1 ) . A l t h o u g h some ore o c c u r s both i n t h e u n d e r l y i n g a n d e s i t e and i n the i n t e r b e d d e d f l o w , most of t h e o r e i s between t h e s e u n i t s . I t may be a replacement o f a t h i n l a y e r o f Q u a t s i n o l i m e s t o n e , o t h e r w i s e u n i d e n t i f i e d . S m a l l pods of c o a r s e c a l c i t e s c a t t e r e d throughout the ore c o u l d be e v i d e n c e of Q u a t s i n o l i m e s t o n e . C h l o r i t e and a l b i t e , accompanied by s e r i c i t e and c a l c i t e , a r e wi d e s p r e a d i n t h e w a l l r o c k v o l c a n i c s . Ore c o n s i s t s of g a r n e t , e p i d o t e , m a g n e t i t e , c a l c i t e , c h a l c o p y r i t e , and b o r n i t e . The s u l p h i d e m i n e r a l s o c c u r as v e i n s , l e n s e s , and d i s s e m i n a t i o n s i n s k a r n and m a g n e t i t e . P y r i t e , p y r r h o t i t e , and a r s e n o p y r i t e a re p r e s e n t i n l e s s e r amounts. In s e v e r a l p l a c e s i n t h e mine, ore and s k a r n are s t r i k i n g l y banded. The bands range f r o m one q u a r t e r t o one i n c h i n t h i c k n e s s and a r e s u b p a r a l l e l t o t h e O l d S p o r t h o r i z o n . The a p p r o x i m a t e p a r a g e n e s i s of t h e m e t a l l i c m i n e r a l s i s : A r s e n o p y r i t e , h e m a t i t e , m a g n e t i t e , c h a l c o p y r i t e - b o r n i t e -p y r r h o t i t e . - 2 3 9 -S e l e c t e d b i b l i o g r a p h y Eastwood,G.E.P. and M e r r e t t , J . E . - O l d S p o r t - B.C. Dept. o f 1961 Mines and P e t r o l . Resources Ann. Rept. 1961, 97-100. ~ J e f f e r y , W . G . - O l d S p o r t - B.C. Dept. o f Mines and P e t r o l . I960 Resources Ann. R e p t . I960, 100-101. Lund,J.C. - Geology and m i n e r a l o g y o f the 5500 l e v e l ore zone 1962 of Coast Copper Mine, Benson Lake, Vancouver I s l a n d , B.C. - U n p u b l i s h e d B.Sc. t h e s i s , U n i v . of B r i t i s h C o lumbia. -214-0-9 . Wesfrob Mines L i m i t e d The p r o p e r t y i s on Tasu Sound, near the e n t r a n c e t o F a i r f a x I n l e t , on t h e w e s t - c e n t r a l c o a s t o f Moresby I s l a n d , Queen C h a r l o t t e I s l a n d s ( F i g . l ) . Greenstones and l a v a s o f the O l d e r V o l c a n i c s , c o r -r e l a t i v e w i t h t h e Karmutsen group on Vancouver I s l a n d (Table 1 ) , a r e the o l d e s t r o c k s exposed i n the a r e a . These are o v e r l a i n by the Kunga f o r m a t i o n c o n s i s t i n g of m a s s i v e l i m e s t o n e , t h i n -bedded d a r k l i m e s t o n e , and a r g i l l i t e . R e g i o n a l mapping has i n d i c a t e d t h a t t h e Kunga f o r m a t i o n i s conformable w i t h o l d e r r o c k s . D r i l l d a t a i n t h e Wesfrob (Tassoo) d e p o s i t suggest the p r e s e n c e o f a major e r o s i o n a l u n c o n f o r m i t y between the two ( p e r s o n a l communication, K. P o l k , r e s i d e n t g e o l o g i s t 1 9 6 2 ) . These l a y e r e d r o c k s a r e near t h e n o r t h e r n t e r m i n a t i o n of the San C r i s t o v a l b a t h o l i t h which i s exposed a l o n g t h e west c o a s t o f Moresby I s l a n d . The b a t h o l i t h i s composed p r i m a r i l y of f o l i a t e d h o r n b l e n d e d i o r i t e . I t has been i n t e r -p r e t e d as a s y n g e n e t i c p l u t o n , younger t h a n M i d d l e J u r a s s i c and o l d e r t h a n p o s t - t e c t o n i c i n t r u s i o n s which invade e a r l y Upper C r e t a c e o u s r o c k s ( S u t h erland-Brown and J e f f e r y , I 9 6 0 ) . S t r u c t u r e i n the mine area i s dominated by a n o r t h -w e s t e r l y - p l u n g i n g s y n c l i n e b o r d e r e d , on each l i m b , by a n t i --214-1 -c l i n e s . Ore d e p o s i t i o n has t a k e n p l a c e i n t h e O l d e r V o l c a n i c r o c k s a l o n g t h e a x i a l zone and west limb of t h e e a s t e r n ant i c l i n e . The m i n e r a l i z e d zone i s d i s t i n c t l y banded and where w e l l d e v e l o p e d , f o u r major ore h o r i z o n s are r e c o g n i z e d by company g e o l o g i s t s . These h o r i z o n s or bands range i n t h i c k n e s s from £ 0 t o 2 0 0 f e e t and can be t r a c e d a l o n g s t r i k e f o r as much as 3 0 0 f e e t . A l o n g s t r i k e t h e s e bands p i n c h and s w e l l so t h a t any one band i s c o n t i n u o u s over l o n g e r d i s t a n c e s . Rock between the ore bands i s composed o f f i n e - g r a i n e d garnet s k a r n or a l t e r e d v o l c a n i c . Three o r e b o d i e s have been d e l i m i t e d a l o n g t h e n o r t h e r l y - t r e n d i n g a x i a l zone o f t h e e a s t e r n a n t i c l i n e . The n o r t h e r n body ( N o . l ) i s c o n t a i n e d almost e n t i r e l y w i t h i n v o l c a n i c r o c k ( g r e e n s t o n e ) , the c e n t r a l and s o u t h e r n bodies (Nos. 2 and 3 ) occur a t t h e c o n t a c t between greenstone and l i m e s t o n e . Most o f the No. 3 d e p o s i t has r e p l a c e d l i m e s t o n e . Ore i s composed p r i m a r i l y of m a g n e t i t e , g e n e r a l l y f i n e - g r a i n e d , mixed w i t h f i n e - g r a i n e d garnet or a l t e r e d v o l c a n i c r o c k . M a g n e t i t e i n t h e No. 3 zone i s d e c i d e d l y more c o a r s e - g r a i n e d and c o n t a i n s l e s s s k a r n than i n the o t h e r two d e p o s i t s . M a g n e t i t e - l i m e s t o n e c o n t a c t s are abrupt and f r e e of s i l i c a t e s . S u l p h i d e s , m a i n l y c h a l c o p y r i t e , occur w i t h m a g n e t i t e and a d i s t i n c t z o n i n g of t h e s e s u l p h i d e m i n e r a l s Is -21+2-e v i d e n t . Copper v a r i e s from 0% i n the No. 1 orebody ( i n green-s t o n e ) t o j u s t over 2% i n the No. 3 orebody ( i n l i m e s t o n e ) . P y r i t e i n c r e a s e s w i t h d e c rease o f c h a l c o p y r i t e , t h e r e b y r e t a i n i n g a c o n s t a n t s u l p h u r c o n t e n t i n the d e p o s i t s . T o t a l s u l p h u r c o n t e n t o f the t h r e e b o d i e s ranges from 2 to J>%. Because the Fe / s r a t i o i n p y r i t e i s t h e same as i n c h a l c o p y r i t e ( O . 8 7 ) , the i n c r e a s e i n copper toward t h e No. 3 zone p o i n t s t o an a f f i n i t y w i t h l i m e s t o n e r a t h e r t h a n a change i n t h e i r o n or s u l p h u r c o n t e n t w i t h i n the d e p o s i t . C h a l c o p y r i t e i n the No. 3 zone was o r i g i n a l l y e x p l o i t e d d u r i n g the y e a r s 1911+-17. P r o d u c t i o n r e c o r d s show t h a t 5 , 1 8 0 tons were mined and c o n t a i n e d 165,566 pounds o f c o p p e r , 1,1+08 oz s i l v e r , and 91+ oz g o l d . The Tassoo d e p o s i t has t h e s e s i m i l a r i t i e s t o o t h e r c o n t a c t metasomatic m a g n e t i t e d e p o s i t s on the west c o a s t : 1. I t i s i n Upper T r i a s s i c l i m e s t o n e and v o l c a n i c r o c k . 2. M a g n e t i t e i s the c h i e f i r o n m i n e r a l . 3 . The d e p o s i t i s a s s o c i a t e d w i t h a f o l d s t r u c t u r e . 1+. Garnet s k a r n has formed i n and around the o r e b o d i e s . 5o The abundance of s u l p h i d e m i n e r a l s , p a r t i c u l a r l y c h a l c o p y r i t e , i n c r e a s e s toward the l i m e s t o n e s i d e of t h e d e p o s i t s . 6 . S k a r n has deve l o p e d t o a much l e s s e r e x t e n t where t h e d e p o s i t r e p l a c e s l i m e s t o n e . 7. C h a l c o p y r i t e c a r r i e s s u b s t a n t i a l amounts of s i l v e r and g o l d . - 21+3 -On t h e o t h e r hand, t h e Tassoo d e p o s i t d i f f e r s from the u s u a l t y p e o f c o n t a c t d e p o s i t s i n the f o l l o w i n g ways: 1. I t i s d e c i d e d l y l a y e r e d , e s p e c i a l l y i n the v o l c a n i c r o c k s where i t c o n s i s t s o f f o u r or more s u b p a r a l l e l t a b u l a r b o d i e s . The reason f o r t h i s l a y e r i n g i s not a p p a r e n t . 2 , I t i s a s s o c i a t e d w i t h t h e San C r i s t o v a l b a t h o l i t h w h i c h , because i t i s w e l l - f o l i a t e d , i s c o n s i d e r e d t o be s y n t e c t o n i c ( Sutherland-Brown and J e f f e r y , I 9 6 0 ) . A l l o t h e r p l u t o n s c o n s i d e r e d i n t h i s s u r v e y o f w e s t e r n B r i t i s h Columbia m a g n e t i t e d e p o s i t s a r e homophanous and t h e r e f o r e thought t o be p o s t - t e c t o n i c . S e l e c t e d b i b l i o g r a p h y Anonymous - The Tassoo i r o n p r o p e r t y - Western M i n e r , 1959 October 1959, 38-1+1+. Bacon,W.R. - Tassoo - B.C. Dept. of Mines Ann. Rept. 1 9 5 6 , 1956 1 2 5 - 1 2 7 . Patterson,R.W. - Economic geology of the Nos. 2 and 3 o r e b o d i e s , Tassoo, B r i t i s h Columbia - M.Sc. t h e s i s ( i n p r e p a r a t i o n ) , U n i v e r s i t y o f B r i t i s h C o lumbia. Sutherland-Brown,A. - Tassoo - B.C. Dept. of Mines and P e t r o l . 1 9 6 1 Resources Ann. Rep t . 1 9 6 1 , 11-13. and J e f f e r y , W . G . - P r e l i m i n a r y g e o l o g i c a l 1 9 6 0 map o f t h e sou t h e r n Queen C h a r l o t t e I s l a n d s , B.C. and Notes on t h e geology - B.C. Dept. of Mines. -214-APPENDIX II The o r i g i n o f " c l o u d e d " f e l d s p a r - A r e v i e w -211.5-The o r i g i n of " c l o u d e d " f e l d s p a r - A r e v i e w MacGregor (1931) has d i s c u s s e d the problem of " c l o u d e d " f e l d s p a r and c o n c l u d e d , from a s e r i e s of f i e l d i n v e s t i g a t i o n s , t h a t such c l o u d i n g "may be due t o the o r i g i n a l o l i g o c l a s e -a n o r t h i t e h a v i n g a h i g h i r o n c o n t e n t and c l o u d i n g i s caused by t h e appearance o f i r o n o x i d e " , presumably h e m a t i t e because such c l o u d i n g i s g e n e r a l l y r e d or p i n k . He f u r t h e r n o t e d t h a t t h e phenomenon i s r e s t r i c t e d t o the i n n e r zones of c o n t a c t a u r e o l e s and appears t o be produced by t h e r m a l metamorphism of the c o u n t r y r o c k . He n o t i c e d , t o o , t h a t the c l o u d i n g i s o f t e n r e s t r i c t e d to t h e more b a s i c p o r t i o n s of zoned p l a g i o c l a s e c r y s t a l s (MacGregor, 1 9 3 1 ,p.5 3 6 ) • In a s e r i e s o f d r y - f u s i o n e x p e r i m e n t s , Faust (1936) showed t h a t i r o n - o r t h o c l a s e c o u l d be formed under t h e s e con-d i t i o n s and c i t e d examples o f n a t u r a l l y - o c c u r r i n g s o l i d s o l u t i o n s o f o r t h o c l a s e and i r o n - o r t h o c l a s e i n w h i c h the l a t t e r wa-s p r e s e n t i n amounts up t o 12%. D u r i n g an i n v e s t i g a t i o n of the r e l a t i o n h e m a t i t e -m i c r o c l i n e , R o s e n q v i s t (1951) noted the o c c u r r e n c e o f i r o n -r i c h f e l d s p a r s and con c l u d e d "... t h a t the f e l d s p a r o r i g i n a l l y c r y s t a l l i z e d from a magma poor i n aluminum or r i c h i n a l k a l i j thus t h e f e l d s p a r became r i c h i n i r o n " . R o s e n q v i s t then -21+6-s u g g e s t e d t h a t a subsequent aluminum metasomatism r e p l a c e d the i r o n and e x p e l l e d i t i n t h e form o f i r o n o x i d e . Both F a u s t and R o s e n q v i s t showed t h a t the e x p e l l e d i r o n was o f the f e r r i c v a r i e t y ( i t r e p l a c e d aluminum i n the f e l d s p a r l a t t i c e ) and presumably, t h e r e f o r e , i t was e x s o l v e d as h e m a t i t e . R a r e l y , m a g n e t i t e i s e x s o l v e d (Carstens,1955)• Temperature i s an im p o r t a n t f a c t o r i n the i n c o r p o r a t i o n of FegO-j i n t o t h e f e l d s p a r l a t t i c e . I t was shown by R o s e n q v i s t (195l,P«73) t h a t a t low temperatures l e s s f e r r i c i r o n c o u l d be h e l d i n the l a t t i c e t h a n a t h i g h . In a more r e c e n t d i s -c u s s i o n , E r n s t (I960,p.301) p o i n t s out t h a t KFeSi^Og i s s t a b l e at magmatic temperatures o n l y at r e l a t i v e l y h i g h o x i d a t i o n s t a t e s . I f p a r t i a l p r e s s u r e o f oxygen were h e l d c o n s t a n t by d i s s o c i a t i o n o f wa t e r , t h e n as i r o n was e x p e l l e d from f e l d s p a r i n a c o o l i n g magma, i t would be r e t a i n e d i n t h e f e r r i c form and h e m a t i t e would be produced. The f o r m a t i o n of i r o n - a l b i t e i s a p p a r e n t l y not p o s s i b l e i n the t e r n a r y system NagSiO^-Fe20^-SiC^ but the e x i s t e n c e of i r o n - a n o r t h i t e has been suggested (Day and A l l e n , 1905). A r e v i e w of the e x i s t i n g t h e o r i e s t o account f o r the c l o u d i n g of p l a g i o c l a s e was p r e s e n t e d by P o l d e r v a a r t and G i l k e y i n I95I4-. I t was suggested t h a t i n t e r n a l phase boundaries i n the unmixed f e l d s p a r would p r o v i d e passage f o r m a t e r i a l i n and out o f the c r y s t a l s and t h a t i n t e n s e c l o u d i n g of f e l d s p a r was p r o b a b l y the r e s u l t of t h i s m i g r a t i o n of i r o n (among o t h e r e lements) i n t o t h e c r y s t a l a f t e r i t s f o r m a t i o n . A s 1 1ght c l o u d i n g , however, was a t t r i b u t e d by t h e s e a u t h o r s t o e x s o l u t i o n of i r o n p r e s e n t i n the f e l d s p a r l a t t i c e at the time of i t s f o r m a t i o n . The a u t h o r s l i s t t h r e e r e q u i s i t e s f o r p l a g i o c l a s e c l o u d i n g : (1) e l e v a t e d t emperature f o r a p r o l o n g e d p e r i o d (2) presence o f water and (3) a s u p p l y of i r o n from the o r i g i n a l r o c k . i r o n - b e a r i n g p l a g i o c l a s e s i s g i v e n below t o demonstrate the a b i l i t y o f p l a g i o c l a s e of d i f f e r i n g c o m p o s i t i o n t o r e t a i n i r o n i n i t s l a t t i c e : (Deer e t a 1 . , 1963,pp . 1 II4.-119) : The average i r o n c o n t e n t (FeO + Fe20^) of s e v e r a l 0 1 i g o c l a s e andes i n e b y t o w n i t e a n o r t h i t e a l b i t e l a b r a d o r i t e 0 . 3 8 % 0.IJ.2 0.14.1 0.60 0 . 3 9 Range 0 . 0 8 - 1 . 3 0 % ) 11 a n a l y s e s 0 . 0 9 - 1 . 1 6 ) 12 0 . 0 7 - 1 . 2 0 ) lh. 0 . 1 5 - 1 . 2 2 ) II4. 0 . 2 0 - 0 , 9 6 ) 13 0 . 0 8 - 0 . 8 3 ) 7 - 2 i i 8 -APPENDIX I I I Che m i c a l a n a l y s e s and norms -21+9-T a b l e 12 C h e m i c a l a n a l y s e s and norms of i n t r u s i o n s near m a g n e t i t e d e p o s i t s ( A n a l y s e s by R.M. S t a f f and A.V. Payne, G e o l . S u r v . , Canada) No. 1. 2. 3 . 1+.' 5 . 6 . 7. Specimen SP-1+9 - 2 0 7 A -MW8 - 3 5 2 A - 3 9 1 A -1+58 -1+97A % % % % % % % s i o 2 5 9 . 8 5 5 . 6 1+7.2 65.9 63 .7 69.1+ 60 . 9 A 1 2 ° 3 18.1 19.1+ 13.1 16 . 7 1 6 . 2 16 .1 17.1 F e 2 0 3 2 . 5 3 . 6 1+.6 0 .81 0 . 5 8 0 . 5 0 2 . 3 FeO 2 . 8 7 3 . 2 8 11 .21 2 . 7 5 [+.80 1 . 9 6 2 . 9 8 CaO 7.1 7.0 8.0 2.1+ 3 . 5 3.0 1+.9 MgO 3.2 3.1 1+.9 1 . 3 1.7 0.61+ 2.9 Na 20 l+.o 3.6 3.7 1+.6 J+.9 3.7 1+.0 KpO 0 . 1 8 2.2 0.91+ 3-3 1.7 3 . 0 1.3 H 2 ° - 0 . 9 2 0.1+2 2.0 0 . 3 2 0.61+ 0.80 1.7 T i 0 2 0 . 7 0 0 . 6 8 3.1 0 . 5 1 0 . 9 0 0.27 0.60 P 2 ° 5 0 . 1 6 0.1+0 1 . 5 0.11 0.26 0 . 0 5 0 . 1 5 MnO 0 . 0 8 0 . 1 8 0 .31 0 . 0 8 0 . 1 5 0 . 0 3 0 . 1 2 c o 2 0 . 0 2 0.00 0 . 1 3 0 . 0 6 0 . 0 7 0.01+ 0.01+ S -- — — 0 . 0 1 0.01+ 0 . 0 2 0 . 0 1 T o t a l 99 .63 99.1+6 1 0 0 . 6 9 99.81+ 99 . 2 1 99 . 5 1 99.00 - 2 5 0 -Table 12 ( c o n t i n u e d ) Norms % % % % % % % Quartz 15.80 7 .26 _ _ 2 7 . 6 0 1 8 . 3 0 16.26 16.62 O r t h o c l a s e 1.11 12.79 5 .56 17 .79 19.1+6 10.01 7 . 7 8 A l b i t e ' 31+.06 3 0 . 3 9 31.I+I+ 3U+1+ 3 8 . 7 7 1+1.39 31+.06 A n o r t h i t e 3 0 . 5 8 3 0 . 3 0 16 .12 15.01 10.81+ 15.57 2 3 . 6 3 Corundum -- — — 1.22 3 . 5 7 0 . 6 1 Di ops i de 3 . 0 9 1.33 11.01+ — — — _ _ Hypersthene 8 . 7 8 9 . 2 8 16.25 1+.37 7 . 0 0 H.1+3 10.07 01 i v i n e _ _ -- 2 . 0 0 __ — _ _ Magnet i t e 3.71 5.31+ 6 . 7 3 0 . 7 0 1.16 0 . 9 3 3 . 2 5 I l m e n i t e 1.37 1.37 5 .93 0 . 6 1 O .91 1.67 1.22 Apat i te 0.31+ 1.01 3 . 7 0 — 0.31+ 0 . 6 7 0.31+ T o t a l 98.81+ 9 9 . 0 7 9 8 . 6 7 98.71+ 1 0 0 . 3 5 98.51+ 9 6 . 9 7 - 2 5 1 -T a b l e 13 Chemical a n a l y s e s and norms of v o l c a n i c r o c k s near m a g n e t i t e d e p o s i t s ( A n a l y s e s by R.M. S t a f f and A.V. Payne, G e o l . S u r v e y , C a n a d a ) - ' No. 1. 2 . 3 . 1+. 5. Spec imen SP-1+5 SP-31I4.B SP - 3 9 0 SP-l+16 SP-1+71 % % % % % S i 0 2 LL6.6 1+9.9 1+9.6 1+-8.5 1+8.1 A 1 2 0 ^ 17.7 1 8 . 0 16.1+ 1 8 . 0 U+.8 F e 2 0 ^ 3 . 0 2 . 6 1.5 3 . 9 2 . 6 FeO 5.73 7 . 0 2 8.1+3 6.58 9 . 5 7 CaO 11.2 8.1 9 . 9 8.5 9.1+ MgO 7.5 6 . 3 6 .5 n . 5 5.6 N a 2 0 2.1 2 . 9 3 . 2 1.8 2 . 3 K 2 0 0 . 3 6 0 . 8 6 0.51+ 0 . 1 0 0 . 1 0 H 2 ° t 1.5 2 . 2 1.1 2 . 6 2 . 9 T i 0 2 2 . 7 0 . 8 5 1.2 O .78 1.8 P2°5 0 . 2 8 0 . 2 0 0 . 1 8 0 . 0 8 0 . 1 9 MnO 0.21 0 . 2 3 0 . 2 1 0 . 1 0 0 . 2 9 c o 2 0.01). 0 . 1 2 0.15 0 . 1 0 2 . 0 s - 0 . 0 2 0.11+ 0 . 3 0 0 . 0 3 T o t a l 9 8 . 9 2 9 9 . 3 0 9 9 . 0 5 99.81+ 9 9 . 6 8 -252-T a b l e 13 ( c o n t i n u e d ) Norms % % % Q u a r t z mm O r t h o c l a s e 0 . 5 6 5.56 2 . 7 8 A l b i t e 15.20 2I4..63 27.25 A n o r t h i te i+0.59 3 3 . 0 8 3 1 . 6 9 Di ops i d e 0 . 6 5 5.19 13.50 Hypersthene 2 3 . 2 2 2 2 . 9 1 11.1+0 01 i v i n e 9.01+ 0.31+ 6 . 0 2 Magnet i t e 5.57 3 . 7 1 2.09 I I m e n i t e 1.52 1.67 2 . 2 8 P y r i t e 1.08 - 0.1+8 Apat i t e 1.01 0.31+ T o t a l 97.77. 9 8 . 1 0 9 7 . 8 3 % -13,. 7 2 0.56-* 1 9 . 3 9 29 . 7 5 1 3 . 3 0 2 0 . 6 3 3 .71 3 . 5 0 % 0 . 3 0 2.22 17 . 8 2 3 7 . 8 1 12 . 5 7 16 . 5 7 M + l 5.71 9 8 . 0 8 -253-T a b l e Iii, Chemical a n a l y s e s o f host r o c k l i m e s t o n e L o c a l i t y I r o n H i l l I r o n H i l l Texada I s . Brynnor Mine Re f e r e n c e Argonaut Company Bacon, 1952 Mathews & McCammon, 1957 Brynnor Mines L t d . % % % I n s o l . 1.29 2.30 ( S i 0 2 = 2.60) R 20^ 0. ILL 0.22 FegO^ 0.6 0.1 0.09 1.17 MnO 0.005 MgO t r a c e 0,02 3.92 CaO 5+. 8 55.5 53.+ I+8.I1 p2°5 0.06 0.008 S 0.01+ 0.07 0.03 Ig. 1oss 1+2.8 H 20 0.08 Equiv.% CaCO^ 98.0 98.9 95.5 86.5 -251+-T a b l e 15 Chemical a n a l y s e s and "norms" o f s k a r n ( A n a l y s e s by R.M. S t a f f and A.V. Payne, G e o l . S u r v ~ Canada) " No. 1. 2 . Specimen S P - 3 7 C SP-196 % % S i 0 2 3 6 . 5 314-.5 A 1 2 0 3 1.6 1.2 F e 2 ° 3 2 8 . 0 2 7 . 7 FeO 1.11 0 . 8 5 MnO 0.1+9 0.7L+ CaO 3 0 . 2 3 0 . 3 MgO 0 . 9 0 0.1+1+ N a 2 ° 0 . 0 2 0.01+ K 2 0 0 . 0 0 0 . 0 0 T i 0 o 2 0 . 0 1 0 . 0 0 P 2 ° 5 0 . 0 7 0 . 0 7 "Norms" Di ops i de A n d r a d i t e Hemat i t e Quartz 10,1+2 8 2 . 7 7 1+. 16 1.38 7 . 8 3 8 5 . 2 7 2 . 5 6 0.06 T o t a l 9 8 . 7 2 9 5 . 7 2 -255-T a b l e 16 L o c a t i o n s of specimens c o l l e c t e d f o r c h e m i c a l a n a l y s i s Specimen L o c a t i o n S P - 3 7 C Garnet s k a r n , 1 6 7 0 l e v e l , Argonaut Co. mine. SP-1+.5 A n d e s i t e , I6I4.O l e v e l , Argonaut Co. mine. SP-I4.9 Quinsam i n t r u s i o n , g r a n o d i o r i t e from o u t c r o p s o u t h of Argonaut Co. mine. S P - I 9 6 Garnet s k a r n , 2 8 6 l e v e l , P r e s c o t t mine, Texada I s l a n d . S P - 2 0 7 A G i l l i e s i n t r u s i o n , q u a r t z monzonite, 2 8 6 l e v e l , P r e s c o t t mine, 3 0 0 f e e t from c o n t a c t w i t h l i m e s t o n e . S P - 2 0 7 B G i l l i e s i n t r u s i o n , a l t e r e d q u a r t z m o n z o n i t e , 2 8 6 l e v e l , P r e s c o t t mine, 1 0 0 f e e t from c o n t a c t w i t h 1imes t o n e . S P - 2 0 7 C G i l l i e s i n t r u s i o n , h i g h l y a l t e r e d q u a r t z monzonite, 2 8 6 l e v e l P r e s c o t t mine, 1 0 f e e t from c o n t a c t w i t h 1imestone. / SP-3H4-B I n t r u s i v e a n d e s i t e , Brynnor Mines L t d . open p i t . S P - 3 5 2 A Quartz m o n z o n i t e , o u t c r o p on h i l l west of Brynnor Mines L t d . open p i t . S P - 3 9 0 A n d e s i t e , 2 5 7 0 l e v e l , Z e b a l l o s I r o n Mines L t d . open p i t . SP - 3 9 1 A Q u a r t z m o n z o n i t e , 2 5 7 0 l e v e l , Z e b a l l o s I r o n Mines L t d . open p i t . SP-I4.I6 A n d e s i t e , Nimpkish I r o n Mines open p i t . SP-I4.58 Q u a r t z m o n z o n i t e , o u t c r o p i n N i m p k i s h R i v e r below c r u s h e r , N i m p k i s h I r o n M i n e s . ' SP-I4.7I A n d e s i t e , Jedway I r o n Ore L t d . open p i t . SP-I+.97A Jedway s t o c k , q u a r t z monzonite, from r a i l w a y cut near m i l l , Jedway I r o n Ore L t d . SP-MW8 Coast Copper s t o c k , gabbro, from o u t c r o p 7 0 0 f e e t west M e r r y Widow mine, Empire Development Co. L t d . - 2 5 6 -APPENDIX IV P l a t e s t o f a c e page 257 PLATE I - Laumontit e ( w h i t e ) v e i n i n g s e r i c i t i z e d Quinsam g r a n o d i o r i t e . I r o n H i l l mine, Argonaut Co, L t d , S c a l e i n photo i s s i x inches l o n g . PLATE II - Replacement of Gillies quartz monzonite by garnet skarn. Transition zone consists of garnet skarn with relict granitic texture. Paxton mine, Texada Mines Ltd. Qm = quartz monzonite; tr = transition rock; sk = skarn. t o f a c e page 2^8 PLATE I I I - Texada group a n d e s i t e p a r t l y r e p l a c e d by garnet s k a r n , P a x t o n mine, Texada Mines L t d , Tg = Texada group; Mb = M a r b l e Bay l i m e s t o n e ; sk = s k a r n . PLATE IV - C o n t a c t between G i l l i e s q u a r t z m o n z o n i t e , M a r b l e Bay l i m e s t o n e , and o r e . P r e s c o t t mine, Texada Mines L t d . Qm = q u a r t z monzonite; Mb = M a r b l e Bay l i m e s t o n e ; sk = P r e s c o t t orebody. to f a c e page 2 5 9 PLATE V - " B r e c c i a o r e " , Y e l l o w K i d mine, Texada Mines L t d . B l a c k = m a g n e t i t e ; w h i t e = c o a r s e l y c r y s t a l l i n e c a l c i t e . PLATE VI - M a g n e t i t e w i t h c a v i t i e s p a r t l y f i l l e d w i t h m i l k y q u a r t z c r y s t a l s and g o e t h i t e (see a r r o w s ) . S h a m r o c k - B l a c k j a c k c l a i m , Empire Development Co. L t d . - 2 5 9 PLATE V PLATE VI t o f a c e p a g e 2 6 0 / P L A T E V I I - G r e e n s t o n e d y k e i n l i m e s t o n e . N o t e t h e n a r r o w g a r n e t s k a r n r i m o n e i t h e r s i d e o f t h e d y k e a d j a c e n t t o l i m e s t o n e . B r y n n o r M i n e s L t d . P L A T E V I I I - M a s s i v e m a g n e t i t e i n c o n t a c t w i t h b e d d e d l i m e s t o n e . The c o n t a c t d i p s t o t h e l e f t a t a s h a l l o w e r a n g l e t h a n t h e l i m e s t o n e ( s e e b e d d i n g p a r a l l e l t o hammer h a n d l e ) . Z e b a l l o s I r o n M i n e s L t d . M = m a g n e t i t e ; lm = l i m e s t o n e . -260-P L A T E V I I PLATE V I I I t o f a c e page 261 PLATE IX - M a g n e t i t e orebody between m i g m a t i t e ( q u a r t z monzonite and a n d e s i t e ) and l i m e s t o n e . Nimpkish I r o n Mines L t d . Mg = m i g m a t i t e ; m = m a g n e t i t e ; lm = l i m e s t o n e . PLATE X - D i o p s i d e c r y s t a l s o f unusual form. The c r y s t a l s were o r i g i n a l l y e n c l o s e d by c a l c i t e . P r e s c o t t mine, Texada Mines L t d . t o f a c e p a g e 2 6 2 P L A T E X I - A n i l l u s t r a t i o n o f t h e t y p i c a l s h a r p m a g n e t i t e -l i m e s t o n e c o n t a c t . L i m e s t o n e ( w h i t e , b e l o w ) r e t a i n s d a r k l a y e r s s u g g e s t i v e o f b e d d i n g . T h e i r r e g u l a r z o n e o f l i g h t -c o l o u r e d m a t e r i a l b e t w e e n m a g n e t i t e a n d l i m e s t o n e ( r i g h t ) i s e u h e d r a l p y r i t e . Y e l l o w K i d m i n e , T e x a d a M i n e s L t d . P L A T E X I I - M a g n e t i t e ( b l a c k ) f i l l i n g f r a c t u r e s i n b r e c c i a t e d a n d e s i t e . A j a x d e p o s i t , E m p i r e D e v e l o p m e n t C o . L t d . P L A T E X I I I - A l t e r n a t i n g l a y e r s o f c o a r s e l y c r y s t a l l i n e m a g n e t i t e a n d c a l c i t e s u g g e s t i v e o f s e l e c t i v e r e p l a c e m e n t o f c e r t a i n l i m e s t o n e b e d s . S h a m r o c k - B l a c k j a c k d e p o s i t , E m p i r e D e v e l o p m e n t C o . L t d . -262-PLATE X I I I to face page 263 PLATE XIV - Same as Plate XIII except that the layers are thinner and much of the calcite has been leached out by weathering. PLATE XV - Contact of garnet skarn and limestone. Note that bedding in the limestone (lower half of specimen) is obliterated in a narrow white zone immediately adjacent to the skarn. Iron Hill mine, Argonaut Co. Ltd. PLATE XVI - An example of colloform magnetite. Note the radial texture in some layers, convex banding, and calcite-filled radial synerisis cracks. Kingfisher mine, Empire Development Co.,Ltd. -263 -PLATE XIV PLATE XV PLATE XVI t o f a c e p a g e 26LL P L A T E X V I I - G a r n e t s k a r n w i t h r e l i c t g r a n i t i c t e x t u r e o f h o s t r o c k q u a r t z m o n z o n i t e . P a x t o n m i n e , T e x a d a M i n e s L t d . P L A T E X V I I I - P o s t - o r e c a l c i t e s u r r o u n d i n g f r a g m e n t s o f m a g n e t i t e . N o t e t h e r o u n d e d e d g e s a n d c o a r s e - g r a i n e d b o r d e r s o f t h e f r a g m e n t s . M a g n e t i t e w i t h c o l l o f o r m t e x t u r e i s f o u n d i n o r e o f t h i s t y p e . K i n g f i s h e r m i n e , E m p i r e D e v e l o p m e n t C o . L t d . P L A T E X I X - S k a r n i f i c a t i o n o f e p i d o t i z e d q u a r t z m o n z o n i t e . Qm = q u a r t z m o n z o n i t e ; s k = s k a r n ; ep = e p i d o t e ; b l a c k = h o r n b l e n d e . t o f a c e page 265 PLATE XX - C a l c i t e ( w h i t e ) f i l l i n g openings between e u h e d r a l a n d r a d i t e c r y s t a l s ( g r e y ) . P l a i n l i g h t . X 5 0 . PLATE XXI - Same as above but w i t h c r o s s e d m i c o l s . Note the a l t e r n a t e i s o t r o p i c and a n i s o t r o p i c zones i n t h e c r y s t a l at upper r i g h t . PLATE XXII - M a g n e t i t e f i l l i n g openings between s u b h e d r a l a n d r a d i t e c r y s t a l s . P l a i n l i g h t . X 5 0 . t o f a c e page 266 PLATE X X I I I - M a g n e t i t e r e p l a c i n g garnet s k a r n outward from openings such as shown i n P l a t e X X I I , r e s u l t i n g i n i s o l a t e d s u b h e d r a l garnet c r y s t a l s . P l a i n l i g h t . X^O. -266-DLATE X X I I I _70 -60 - 5 0 <D .40 u-c o —30 — 20 F e m = 1.08 (Fet) - 6.94 Correlation coefficient = 0.991 N = 208 10 20 30 40 Iron as magnetite ( F e m ) , weight % 50 60 FIGURE 10 Merry Widow mine, drill hole assays. Plot of total iron (Fe^) versus iron as magnetite (Fe m ) . Line fit by linear regression. MAP I T H E ARGONAUT COMPANY LIMITED GEOLOGY O F IRON HILL MINE P L A N OF O P E N PIT JUNE, 1961 50 25 0 50 CZZ] if • • r i J BUM Quinsam granodiorite '" Limestone , v ; . Volcanics " v' : . Massive magnetite Skarn Mixed rock- magnetite and skarn •  • • ' ' i. Mixed rock- volcanics and gronodiorite' v Geologic contact (defined, assumed) Talus covered orea — Pit bench outline y "< Water level M A P 3 T E X A D A MINES LIMITED GEOLOGY OF YELLOW KID MINE PLAN OF O P E N PIT JULY, 1961 50 25 0 50 Ezzza 1* i . . . J J fX''\ t*a tKt l-*J *\/ Feldspar porphyry Gillies stock-quartz monzonite Marble Bay formation- limestone i . . . Massive magnetite Skarn Mixed rock-quartz monzonite and skarn Approx. limit of main ore zone Geologic contact (defined, assumed) Fault Talus covered area Pit bench outline 50 MAP 4 T E X A D A MINES LIMITED G E O L O G Y O F PAXTON MINE P L A N OF OPEN PIT JULY, 1961 25 0 50 •i^'^J'S^t- Feldspar porphyry mm E S S . C 3 » « » » < JX>'\ 'Gtllies stocK-quartz: monzonite Marble Bay. formation- •limestone Texada. group- andesite .. Massive magnetite Skarn Mixed rock- magnetite and skarn Mixed rock-quartz monzonite. and .skarn • Mixed rock- andesite and skarn - -Approx. limit of main are zone Geologic contact (defined, .assumed) : Fault Talus covered: area . Pit bench outline -M A P 6 Massive magnetite Skarn (including some serpentine) . Approx. limit of main ore zones BRYNNOR MINES LIMITED G E O L O G Y OF O P E N PIT J U N E , 1962 100 50 0 100 S i I I i l l T u ( t Feldspar porphyry, leucodiorite Quartz monzonite Intrusive andesite- Bonanza(?) group "1 Quatsino(?) formation Limestone J ' \ Geologic contact (defined, assumed) Fault M A P 7 Z E B A L L O S IRON MINES LIMITED GEOLOGY O F F.L.(FORD) MINE P L A N OF O P E N PIT AND ORE ZONE J U L Y , 1962 100 50 0 100 Bonanza group- andesite Quatsino formation- limestone I Massive magnetite ^ Skarn » i ' f i i i ! Mixed rock- andesite and skarn fL'iill^ f Mixed rock- andesite and quartz monzonite S \ „ Approx. limit of main ore zone Geologic contact (defined, assumed) Fault Talus covered area Pit bench outline MAP e NIMPKISH IRON MINES LIMITED GEOLOGY OF IRON CROWN (KLAANCH) MINE PLAN OF OPEN PIT JULY, !962 50 25 50 EW3 y ' f t n t f r i i i l l i H ' l l E r a Aplite Feldspar porphyry mm r — 3 if f T l i 13 tfii!Jtii*-M^iVilBpl ^ 3 ... . . . . . f quartz monzonite Nimpkish intrusions- i j j 0 r i } e Bonanza(?) group- felslte Bonanza group- andesite Quatsino formation- limestone Massive magnetite Skarn Mixed rock- andesite and skarn Mixed rock- diorite and skarn y / V ' Approx. limit of main ore zone . V. Geologic contact (defined, assumed) Fault Talus covered area Pit bench outline M A P 9 JEDWAY IRON O R E LIMITED G E O L O G Y OF JESSIE MINE P L A N OF O P E N PIT A U G U S T , 1962 50 25 50 f~~1 F e l d s p a r p o r p h " r y if1' v ^ ^ ' j i J r .^- ' - .^ ' i i Jedway stock- quartz monzonite Argillite; thin bedded limest e "| _ _ _ _ _ _ _ _ (Kunga X////\ Massive limestone J formation Older volcanics- andesite Massive magnetite Mixed rock- andesite and quartz monzonite Geologic contact (defined, assumed) Fault Talus covered area Pit bench outline 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0053070/manifest

Comment

Related Items