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Geology of the Deer Horn prospect, Omineca M.D., British Columbia Papezik, Vladimir Stephen 1957

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GEOLOGY OF THE DEER HORN PROSPECT, OMINECA M.D. , BRITISH COLUMBIA  by VLADIMIR STEPHEN PAPEZIK B.A., U n i v e r s i t y o f B r i t i s h Columbia,  1954  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of GEOLOGY  We accept t h i s t h e s i s as conforming  THE  t o the r e q u i r e d  UNIVERSITY OF BRITISH COLUMBIA A p r i l 1957  standard  ABSTRACT  The  Deer Horn p r o p e r t y l i e s a s t r i d e the contact  the Coast Range b a t h o l i t h and  a group of s i l i c e o u s and  sediments of J u r a s s i c or Lower Cretaceous age. s t r i k e s w e s t e r l y and dips about 50° southern itic  The  shaly  contact  to the South.  The  three f i f t h s o f the p r o p e r t y are u n d e r l a i n by  r o c k s , the remaining  gran-  n o r t h e r n p a r t c o n s i s t s of s l i g h t l y  metamorphosed sediments s t r i k i n g approximately  west, d i p p i n g  about 70°  south and b e l i e v e d to form an overturned  The  are cut by two  rocks  of  a l b i t i t e dykes and  syncline.  s e v e r a l minor t r a p  dykes. The  g r a n i t i c rocks are d i v i d e d i n t o two main  " p o r p h y r i t i c " g r a n o d i o r i t e and l a t t e r contains  hornblende g r a n o d i o r i t e .  i n t o s e v e r a l v a r i e t i e s produced by  o n i c movements and hydrothermal a l t e r a t i o n . a f f e c t e d both the g r a n i t i c rocks  extent - the sediments. in  The  the main part of the m i n e r a l d e p o s i t , and i s  further subdivided  ism has  types,  tect-  A l k a l i metasomat-  and - to a l e s s e r  Some metasomatic f e a t u r e s are  discussed  detail. Two  v e i n s or v e i n systems, the Main and  l i e i n the hornblende g r a n o d i o r i t e and  the  i n the contact  They s t r i k e w e s t e r l y , converge towards the west and each o t h e r , forming  a shallow  troughlike structure.  c a r r y s u l p h i d e s and minor t e l l u r i d e s w i t h gold and  Contact, zone.  d i p towards Both silver.  S c h e e l i t e occurs s p a r s e l y i n the v e i n s and i n bands o f e p i d o t e garnet s k a r n i n the sediments, being somewhat more c o n c e n t r a t e d i n two areas of f i n e t a l u s i n the western p a r t o f the p r o p e r t y . The Main v e i n i s shown t o be a replacement formed  i n a thrust f a u l t .  vein  The s h e a r i n g angle o f the f a u l t  f l a t t e n e d i n the more b r i t t l e contact zone, and the f a u l t minated  i n a s e r i e s o f complementary s h e a r s .  o f these two f a c t o r s produced  ter-  The combination  the c u r v i n g t r o u g h - l i k e shape o f  the v e i n . The narrow Contact v e i n was formed fault.  i n a later  gravity  The zone o f i n t e r s e c t i o n of the two v e i n s was h i g h l y  sheared and thus rendered more permeable t o the m i n e r a l i z i n g fluids.  T h i s accounts f o r the numerous high-grade  stringers  present near the i n t e r s e c t i o n . In view o f the known and i n f e r r e d l i m i t s o f the two veins i t i s not expected that the ore w i l l continue e i t h e r l a t e r a l l y or i n depth.  In p r e s e n t i n g the  this thesis in partial fulfilment  requirements f o r an advanced degree at the  of  University  o f B r i t i s h Columbia, I agree t h a t  the  L i b r a r y s h a l l make  it  and  study.  f r e e l y available f o r reference  I  further  agree t h a t permission f o r e x t e n s i v e copying o f 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 o f  Department or by h i s r e p r e s e n t a t i v e .  my  I t i s understood  t h a t copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l gain  s h a l l not  be allowed without my  Department The U n i v e r s i t y of B r i t i s h Vancouver 8, Canada. Date  Columbia,  written  permission.  ACKNOWLEDGMENTS  The w r i t e r president enabling  i s g r e a t l y indebted to Dr. D.R.Derry,  o f R i o Canadian E x p l o r a t i o n , him to c o l l e c t  f o r a f i n a n c i a l grant  the specimens on the p r o p e r t y ; t o  Mr. H.R.Buckles, managing d i r e c t o r o f T e c h n i c a l s u l t a n t s , who placed writer's  Mine Con-  a l l company maps and r e p o r t s  a t the  d i s p o s a l ; t o Drs. K.C. McTaggart, R.M. Thompson,  W.H. White and J.V. Ross f o r t h e i r h e l p and f r u i t f u l ions during  suggest-  the i n v e s t i g a t i o n , and to Mr. J.A. Donnan f o r  h i s e x p e r t l y made t h i n - s e c t i o n s .  TABLE OF CONTENTS Page PART I . CHAPTER I . 1. 2. 3. 4. 5. 6. 7.  L o c a t i o n and access P h y s i c a l features C l i m a t e , water, timber Claims and camp f a c i l i t i e s H i s t o r y and development of the p r o p e r t y Previous g e o l o g i c a l work Basis of this i n v e s t i g a t i o n  Table of formations Regional s e t t i n g  CHAPTER I I I .  Petrology  Coarse " p o r p h y r i t i c " g r a n o d i o r i t e Hornblende g r a n o d i o r i t e A l t e r a t i o n phases of hornblende granodiorite (1) (2) (3) (4)  (d)  10 . . . . 10 13 15  "Mine" g r a n o d i o r i t e 15 Sheared s i l i c i f i e d g r a n o d i o r i t e . . 17 G n e i s s i c b i o t i t e - g r a n o d i o r i t e . . . 18 Other a l t e r e d types 20  Mutual r e l a t i o n s  Sedimentary and metamorphic rocks (a) (b) (c) (d) (e) (f)  7 7  GEOLOGY OF THE PROPERTY  G r a n i t i c rocks (a) (b) (c)  2.  . . . .  1 2 3 4 4 5 6  R e g i o n a l Geology  PART I I .  1.  1  Introduction  CHAPTER I I . 1. 2.  GENERAL  T a b l e of rock u n i t s Carbonaceous greywacke Coarse arkose Feldspathic quartzite Black a r g i l l i t e Brown a r g i l l i t e Chiastolite schist F e l d s p a t h i c greywacke  21 24 26 26 27 28 30 30 32 33  Page 3.  34  Dyke Rocks  34  (a) A l b i t i t e (b) H o r n b l e n d e l a t i t e 4.  35  ("trap")  36  Rocks a f f e c t e d by metasomatism  36 38 40 44  (a) E p i d o t e - g a r n e t s k a r n . . (b) Quartz-wollastonite-garnet skarn (c) P e r t h i t e - q u a r t z c a t a c l a s i t e (d) A l k a l i metasomatism CHAPTER I V S t r u c t u r e 1. 2. 3. 4.  G r a n i t i c rocks C o n t a c t b e t w e e n g r a n i t i c and s e d i m e n t a r y Sedimentary rocks The v e i n s (a) (b) (c) Cd) (e)  5.  Post-mineral faults  CHAPTER V. 1. 2. 3. 4.  Mineralogy  .  49 50 51 53 53 55 56 57 61 62  of the veins  P r e v i o u s work The M a i n v e i n The C o n t a c t v e i n O r i g i n of the vein minerals  CHAPTER V I . 1. 2. 3. 4.  The M a i n v e i n The C o n t a c t v e i n Junction of the veins O r i g i n of the veins Summary  rocks  69 69 71 74  Tungsten m i n e r a l i z a t i o n  Introduction S c h e e l i t e i n the veins Scheelite i n skarn The " s c h e e l i t e s l i d e s "  Bibliography  76 76 77 78 80  ILLUSTRATIONS Key map Surface geology, Deer Horn P r o p e r t y G e o l o g i c a l P l a n , 4260 l e v e l  Sect i  F i g u r e 1. " 2. " 3.  "  "  4. 5.  Plate 1. " 2. " 3. " 4« " 5. " 6. " 7. " 8. " 9. " 10.  a f t e r p. 1 . i n pookot^ i ^ & p . ~ -i-n~-p©-ek-et I ^bmeiy  Reaction curves f o r w o l l a s t o n i t e . . . Composition diagrams f o r w o l l a s t o n i t e Vandeveer p a r a g e n e t i c diagrams . . . . Main and Contact v e i n s V e i n p a t t e r n , 4260 a d i t F a u l t p a t t e r n , 4260 a d i t .  a f t e r p. 40 a f t e r p. 40 a f t e r p. 75 -in- poe-k-e-tr-l map -i-n-px^eke^ j ^ . n e t  Mt. L i n d q u i s t with mine camp and a d i t . . . . p. View from the a d i t towards the East . . . . p. Coarse p o r p h y r i t i c g r a n o d i o r i t e p. Chiastolite schist p. Orthoclase porphyroblast i n c a t a c l a s i t e . . . p . O r t h o c l a s e p o r p h y r o b l a s t i n g r a n o d i o r i t e . . p. Contact v e i n , low grade p. Contact v e i n , h i g h grade p. H e s s i t e i n Contact v e i n , microphotograph . . p. H e s s i t e i n Main v e i n , microphotograph. . . . p.  The w r i t e r i s indebted to Mr. No. 3 to 8.  L y a l l Armstrong f o r  Plates  &1 81 82 82 83 83 84 84 85 85  GEOLOGY OF THE DEER HORN PROSPECT OMINECA M.D., BRITISH COLUMBIA  PART I CHAPTER I  INTRODUCTION  1.  L o c a t i o n and Access The Deer Horn p r o p e r t y , a g o l d - s i l v e r - t u n g s t e n  prospect, l i e s  i n a rugged p a r t o f the Coast Mountains o f  B r i t i s h Columbia, a t 53 deg. 22« North l a t . , 127 deg. 18 l o n g . , i n the Omineca Mining D i v i s i o n . settlement  West  The nearest major  and r a i l w a y s t a t i o n i s Burns Lake, a s m a l l town on  the main Canadian N a t i o n a l Railway Rupert;  1  l i n e from Edmonton t o P r i n c e  i t l i e s about 85 m i l e s n o r t h e a s t o f the p r o p e r t y .  From Burns Lake, the prospect i s a c c e s s i b l e i n two ways: e i t h e r by a c h a r t e r e d plane l a n d i n g on L i n d q u i s t Lake, connected  by a  four m i l e t r a c t o r road t o the mine camp, or 25 m i l e s by road t o W i s t a r i a on the n o r t h shore o f Ootsa Lake and then 55 m i l e s by boat to the western end o f W h i t e s a i l Lake. leads from t h i s l a n d i n g t o Lake L i n d q u i s t .  A two m i l e road  showing  position  of  the  Deer  Horn  property  2 2.  P h y s i c a l Features The  area i n which the p r o p e r t y i s s i t u a t e d l i e s  the e a s t e r n s l o p e of the P a c i f i c Ranges of the Coast Near the p r o p e r t y and  until  Mountains.  to the West the country has a rugged  topography and a h i g h r e l i e f ; comes lower and  the sharp  towards the E a s t , the r e l i e f  peaks give way  Nechako P l a t e a u .  Long narrow l a k e s , such as Tahtsa, Morice, W h i t e s a i l and are t y p i c a l f o r the r e g i o n .  Both shores  of these lakes  Eutsuk are  f l a n k e d by n o r t h e a s t e r l y t r e n d i n g ranges which r e p r e s e n t t r a n s i t i o n between the Coast Mountains proper  time, and  e n t i r e area was  covered  be-  to more rounded summits,  they f i n a l l y merge w i t h the r o l l i n g  The  on  a  and the p l a t e a u .  by i c e during P l e i s t o c e n e  g l a c i a l e r r a t i c s and s t r i a e are common on some  mountain r i d g e s . N 60-70 deg. E.  The  u s u a l d i r e c t i o n of these s t r i a e i s about  A few n a i l h e a d s t r i a e observed  by the w r i t e r  on Mount Chikamin, south o f W h i t e s a i l Lake, trend N 65  E.  The western part of the a r e a , p a r t i c u l a r l y west of Deer Horn, is  even today c h a r a c t e r i z e d by a l p i n e g l a c i a t i o n , and  snowfields  small  and c i r q u e g l a c i e r s are common. The Deer Horn p r o p e r t y l i e s  L i n d q u i s t Peak, extending q u i s t at 2900'  on the southern  s l o p e of  from the n o r t h shore of Lake L i n d -  to the summit more than 5800' h i g h .  The  greater  p a r t of the p r o p e r t y and most of the m i n e r a l showings l i e above t i m b e r l i n e . r i d g e and  Outcrops are numerous near the top o f the  i n the short i n t e r m i t t e n t creeks  d r a i n i n g the mount-  3 ain  s i d e , but a l a r g e p o r t i o n of the a r e a , i n c l u d i n g some  c r i t i c a l s e c t i o n s , i s covered zones of s t r o n g s h e a r i n g .  by f i n e t a l u s , p a r t i c u l a r l y i n  Short  grass covers most of the ground  f a r t h e r below the mountain r i d g e , and  l a r g e outcrops  become  r a r e below t i m b e r l i n e . 3.  C l i m a t e , Water, Timber The  area has  a t y p i c a l coastal climate with  frequent  t  r a i n and h i g h s n o w f a l l . winter months and  Both lakes are f r o z e n d u r i n g  are s u i t a b l e f o r ski-equipped  W h i t e s a i l Lake begins  to break up e a r l y i n May  can u s u a l l y land at Deer Horn Bay  the  aircraft. and  float  i n the second h a l f of the  month, w h i l e L i n d q u i s t Lake u s u a l l y remains f r o z e n u n t i l June.  The  u n t i l l a t e August.  S m a l l patches of snow i n s h e l t e r e d v a l l e y s do not throughout the year. and  and new  late  lower p a r t s of the p r o p e r t y are f r e e of snow by  e a r l y J u l y , the upper p a r t s remain covered  fog  planes  rain.  Night  snow may  disappear  Summers are o f t e n hot, but w i t h  frequent  f r o s t s appear by the middle of September  be expected  i n the f i r s t  h a l f of October.  Both lakes f r e e z e again e a r l y i n December. Water supply f o r camp and mine purposes i s good to  4300 f e e t , i n s e v e r a l s m a l l but permanent creeks.  t h i s e l e v a t i o n there are o n l y s h o r t creeks  S u f f i c i e n t timber  Above  fed by m e l t i n g  snow; t h e i r flow v a r i e s w i t h the r a t e of m e l t i n g and c o n s i d e r a b l y toward the end  up  decreases  of September. i s a v a i l a b l e at lower e l e v a t i o n s ,  p a r t i c u l a r l y i n the t h i c k l y wooded v a l l e y between W h i t e s a i l  4 and L i n d q u i s t Lakes. 4.  Claims  and Camp  The  c h i e f s p e c i e s are spruce and  hemlock.  Facilities  The Deer Horn p r o p e r t y c o n s i s t s of 26  fullsized  claims and 4 f r a c t i o n s , a l l of them Crown granted. S e v e r a l b u i l d i n g s have been e r e c t e d i n d i f f e r e n t p a r t s of  the area by the owners and  camp, near the entrance  e x p l o r a t i o n companies.  The main  to the a d i t , l i e s at an e l e v a t i o n of  about 4200 f e e t at the end of the mine road.  I t has  two  pre-  f a b r i c a t e d huts which were used as bunkhouse, cookhouse, o f f i c e and assay l a b o r a t o r y , a core shack and a mechanic's shop.  Two  s m a l l e r huts are s i t u a t e d i n the e a s t e r n p a r t of the p r o p e r t y , one hut at L i n d q u i s t Lake and  one near the l a n d i n g at W h i t e s a i l  Lake. 5.  H i s t o r y and Development of the P r o p e r t y The  o r i g i n a l claims were staked i n September 194-3  by  the H a r r i s o n brothers of W i s t a r i a , to cover the s c h e e l i t e showings i n the western p a r t of the p r o p e r t y .  During the examin-  a t i o n of the showings i n 194-4, F.R.Joubin n o t i c e d the g o l d  and  s i l v e r r b e a r i n g v e i n s to the East and a d d i t i o n a l claims were staked.  In the summer of 194-4  the group was  optioned by  the  Pioneer Gold Mines L t d . , and an extensive program o f t r e n c h i n g and diamond d r i l l i n g was  c a r r i e d out i n the years 194-4,  1945  13,000 f e e t of d r i l l i n g  the  and 1946.  A f t e r three years and  o p t i o n was  allowed to l a p s e .  5 The  group was then bought i n 1950 by the Deer Horn  Mines and a f t e r more d e t a i l e d examinations develop the p r o p e r t y .  i t was decided to  I n 1953 a road was c o n s t r u c t e d  from  W h i t e s a i l t o L i n d q u i s t Lake, and about 1000 f e e t o f d r i l l i n g were done t o check the w e s t e r l y e x t e n s i o n o f the v e i n s and the s c h e e l i t e showings, without much success.  I n 1954- the road was  extended t o the present camp s i t e , the main camp was b u i l t and i n August 1954- an a d i t was c o l l a r e d on a v e i n outcrop a t an e l e v a t i o n o f 4260 f e e t . end o f October  Work i n the a d i t continued t i l l the  1955> when a t o t a l o f 1568 f e e t o f underground  workings was completed.  In a d d i t i o n , 6700 f e e t o f diamond  d r i l l i n g , both s u r f a c e and underground, were done d u r i n g the year. pending  At the end o f October  1955 the camp was c l o s e d down  f u r t h e r d e c i s i o n by the company.  The p r o p e r t y i s now  idle. 6.  Previous G e o l o g i c a l Work The p r o p e r t y was examined s h o r t l y a f t e r i t s d i s c o v e r y  i n 1944 by S.S. Holland f o r the B.C. Department o f Mines ( H o l l a n d , 194-4).  The W h i t e s a i l Lake a r e a , i n c l u d i n g the  p r o p e r t y , was mapped i n 1952 by S. D u f f e l l f o r the GSC  (Duffell,  1952), and the prospect was re-examined i n 1955 by W.R.Bacon of the B.C. Department o f Mines (Bacon,  1955).  S e v e r a l company g e o l o g i s t s worked on the p r o p e r t y , i n c l u d i n g F.R.Joubin (1944), A.E. Pike ( 1 9 4 5 ) , E . G . L a n g i l l e ( 1 9 4 5 ) , Charles Ney, (1947)", Paul Young ( 1 9 5 3 ) , D. Ross  (1954)  R. MacRae ( 1 9 5 3 ) , S.L.Learning  (1955).  (1954-55)  and V.S.Papezik  6 Surface  mapping was  property and  done c h i e f l y by F.R.Joubin.  were mapped i n some d e t a i l by P i k e , Ross and  p o s s i b l y by other  g e o l o g i s t s whose maps were not  for this investigation.  The  i n p a r t by S.L.Learning and ( 1 9 5 0 )  Parts  of  the  Papezik, available  underground workings were mapped  p a r t l y by 7.S.Papezik.  s t u d i e d the mineralogy of the v e i n s  A.C.Taplin  at the U n i v e r s i t y  o f B r i t i s h Columbia. 7.  Basis  of t h i s  Investigation  The work was  g r e a t l y f a c i l i t a t e d by  knowledge of the p r o p e r t y  gained by the w r i t e r i n the s i x  months spent at Deer Horn as mine g e o l o g i s t . he was  personal  During that time  engaged mainly i n underground mapping and  d i r e c t i o n of  diamond d r i l l i n g ; he mapped o n l y a s m a l l p a r t of the i n the v i c i n i t y of the s c h e e l i t e showings. volving surface  to the p r o p e r t y  Deductions i n -  exposures are made mostly on the b a s i s  F.R.Joubin s s u r f a c e map. 1  surface  of  In September 1 9 5 6 the w r i t e r  f o r four days to c o l l e c t  returned  the specimens on which  the main p a r t of t h i s work i s based. Beside a great number of hand specimens, 22 s e c t i o n s and  thin-  a number of p o l i s h e d s e c t i o n s were s t u d i e d ,  s e v e r a l minerals  were i d e n t i f i e d by X - r a y s .  and  CHAPTER I I REGIONAL GEOLOGY  1.  T a b l e o f Formations  Formations  o c c u r r i n g i n the v i c i n i t y o f the Deer Horn P r o p e r t y (After D u f f e l l ,  Age Unknown  1952) A l b i t i t e dyke, b a s a l t dykes  I n t r u s i v e contact Jurassic and l a t e r Coast  intrusions  Granodiorite, granite etc.  diorite,  I n t r u s i v e contact w i t h H a z e l t o n Group, i n p a r t i n t r u s i v e i n t o Lower Cretaceous beds Lower Cretaceous  A r g i l l i t e , arkose, b r e c c i a , t u f f , andesite, basalt. Probable  Jurassic  2.  H a z e l t o n Group  unconformity Breccia, t u f f , andesite, b a s a l t ; a r g i l l i t e , greywacke, c h e r t , conglomerate, minor limestone.  The Deer Horn Claim Group i n the R e g i o n a l S e t t i n g The p r o p e r t y l i e s on the e a s t e r n contact o f the Coast  Range b a t h o l i t h and a t h i c k s e r i e s o f sedimentary  and p o s s i b l y  8  some v o l c a n i c r o c k s , which i n t h i s area form an embayment about 6 m i l e s long and 4 m i l e s wide, p r o j e c t i n g i n t o the b a t h o l i t h .  southwesterly  The sediments n o r t h o f L i n d q u i s t Lake  have been mapped by S. D u f f e l l  (1952) as p a r t o f the H a z e l t o n  Group of J u r a s s i c age. However, s e v e r a l f a c t s found d u r i n g the underground work and l a t e r i n v e s t i g a t i o n do not f u l l y support t h i s  classification.  Duffell  ( 1 9 5 2 , p. 5) says of the Hazelton Group:  The most common and c h a r a c t e r i s t i c rocks o f the group are v o l c a n i c t u f f s and b r e c c i a s . Fragments c o n s i s t l a r g e l y o f v o l c a n i c r o c k s , but i n c l u d e minor amounts of sedimentary and p l u t o n i c m a t e r i a l s . The fragments range from f i n e ash to blocks a f o o t or more i n l e n g t h , but most a r e \ t o \ i n c h long ... ( P o r p h y r i t i c ) l a v a flows o f a n d e s i t i c and b a s a l t i c composition form a l a r g e p a r t o f the H a z e l t o n Group ... The sedimentary rocks i n c l u d e f i n e - g r a i n e d b l a c k a r g i l l i t e , minor impure limestone, thin-bedded, grey-green c h e r t , and others best d e s c r i b e d as " t u f f a c e o u s greywackes"... Some o f the beds c o n t a i n a h i g h percentage o f carbonate. On p. 6 he d e s c r i b e s a group o f Lower  Cretaceous  rocks o c c u r r i n g on Swing Peak and L a v e n t i e Mountain, about 20 miles North o f L i n d q u i s t Lake: ... a s e r i e s o f interbedded b l a c k a r g i l l i t e s , fawn t o grey arkoses and minor v o l c a n i c r o c k s , w i t h an aggregate t h i c k n e s s o f about 5000 f e e t . A r g i l l i t e predominates near the base o f the s e c t i o n , and the arkoses a r e t h i n bedded near the base but become t h i c k e r higher i n the series. These ... are succeeded by a v o l c a n i c s e r i e s of t u f f s , b r e c c i a s and f l o w s , very s i m i l a r to those o f J u r a s s i c age. The r e l a t i o n s h i p o f Cretaceous rocks t o J u r a s s i c s t r a t a i s u n c e r t a i n , but i s probably r e p r e s e n t e d by an unconformity. No a c t u a l c o n t a c t s were observed, but the Cretaceous rocks s t r i k e n e a r l y west and d i p s o u t h e r l y , w h i l e the J u r a s s i c rocks s t r i k e a l i t t l e east o f North w i t h dips both east and west.  9  As w i l l be shown l a t e r , the sediments on the Deer Horn p r o p e r t y are a s e r i e s of a r g i l l i t e s , q u a r t z i t e s and koses, s t r i k i n g w e s t e r l y and d i p p i n g to the South.  ar-  The w r i t e r  has not seen any rocks on or near the p r o p e r t y t h a t c o u l d be d e f i n i t e l y d e s c r i b e d as v o l c a n i c t u f f s or b r e c c i a s , a l t h o u g h he has  examined v o l c a n i c rocks c l o s e l y corresponding to the  above d e s c r i p t i o n on Mount Chikamin, 10 chert was  found on the p r o p e r t y .  m i l e s to the E a s t .  O c c a s i o n a l pebbles  p o r p h y r i t i c l a v a occur i n f l o a t , but s i n c e they may e i t h e r group, they are not d i a g n o s t i c .  No  of p u r p l i s h belong to  On the other hand,  the Deer Horn sediments are i n p a r t l i m y , which agrees more w i t h the d e s c r i p t i o n of the H a z e l t o n Group. The w r i t e r has not seen the type rocks f o r the Lower Cretaceous Swing Peak Group, and i n the absence of f o s s i l s i t i s i m p o s s i b l e to prove t o which of the two on the Deer Horn p r o p e r t y belong.  groups the sediments  But on the b a s i s of  s t r u c t u r e and l i t h o l o g y a l o n e , t h e i r c o r r e l a t i o n w i t h the H a z e l ton Group i s open to some doubt. l e a s t p a r t of the sedimentary  I t i s c o n c e i v a b l e t h a t at  embayment at L i n d q u i s t Peak  c o r r e l a t e s w i t h the Swing Peak Group. T h i s p o s s i b i l i t y i s admitted map "May  (1952)  on h i s  under the symbol f o r the H a z e l t o n Group remarks:  i n c l u d e some u n d i f f e r e n t i a t e d 3."  beds).  by D u f f e l l , who  ( i . e . Lower  Cretaceous  10  PART I I GEOLOGY OF THE DEER HORN PROPERTY  CHAPTER I I I PETROLOGY  1.  G r a n i t i c Rocks G r a n i t i c rocks  property.  u n d e r l i e the g r e a t e r p a r t o f the  On the b a s i s o f t h e i r m i n e r a l  composition they can  a l l be c l a s s i f i e d as g r a n o d i o r i t e , but s e v e r a l types have been recognized.  The d i f f e r e n c e s between them l i e mainly i n v a r i a -  tions of mineral  proportions,  i n the a n o r t h i t e content o f the  p l a g i o c l a s e , and i n t e x t u r e . (a)  Coarse " p o r p h y r i t i c " g r a n o d i o r i t e The  "porphyritic" granodiorite i s a fresh-looking  medium t o coarse-grained  p i n k i s h g r a n i t i c rock c o n t a i n i n g  spicuous euhedral c r y s t a l s o f o r t h o c l a s e  up t o 1 i n c h  con-  across.  Quartz, o r t h o c l a s e and p l a g i o c l a s e are e s s e n t i a l m i n e r a l s , accessories  are brown b i o t i t e , a p a t i t e and sphene.  The l a t t e r  occurs commonly i n euhedral wedge-shaped c r y s t a l s up t o 1 mm long and  mm wide.  S m a l l amounts of c h l o r i t e and s u l p h i d e s  were found i n the t h i n - s e c t i o n .  F i n e f l a k e s o f o b i o t i t e form  narrow rims around some o f the prominent o r t h o c l a s e c r y s t a l s and  are a l s o enclosed  i n them.  11 Quartz forms about 20$ o f the rock.  I t occurs i n  c l e a r g l a s s y anhedral g r a i n s 3-10 mm a c r o s s . it  In t h i n - s e c t i o n ,  i s s l i g h t l y f r a c t u r e d and shows weak strain-shadows.  i n t e r s t i t i a l t o euhedral p l a g i o c l a s e  crystals.  The p l a g i o c l a s e shows euhedral t o subhedral o n l y s l i g h t l y corroded, w i t h w e l l developed zoning.  It is  forms,  normal o s c i l l a t o r y  T h i s i s a d i s t i n g u i s h i n g f e a t u r e , not found i n any  of the other g r a n i t i c rock types examined. the p l a g i o c l a s e , determined  The composition o f from An 33  i n f i v e g r a i n s , ranges  i n the core t o An 22 i n the outer zone, averaging about An 2 7 . The p l a g i o c l a s e i s only s l i g h t l y a l t e r e d to s e r i c i t e , and many grains a r e q u i t e c l e a r . O r t h o c l a s e occurs i n two d i f f e r e n t ways:  as s m a l l  anhedral g r a i n s i n t e r s t i t i a l t o p l a g i o c l a s e , and as l a r g e o v a l shaped g r a i n s about 1 i n c h square.  Some o f the l a t t e r have  i n d e f i n i t e boundaries, e n c l o s i n g many s t r o n g l y corroded  relics  o f q u a r t z , p l a g i o c l a s e , b i o t i t e and sphene; o t h e r s , much l e s s common, a r e euhedral o r t h o c l a s e c r y s t a l s without rim which c h a r a c t e r i z e s the f i r s t mentioned  the b i o t i t e  type.  The l a r g e g r a i n s are somewhat cloudy because o f a l t e r ation to clay minerals.  T h e i r o p t i c a l o r i e n t a t i o n i s uniform,  but u n d u l a t i n g and m i n u t e l y i r r e g u l a r i n d e t a i l .  They c o n t a i n  wavy, branching but g e n e r a l l y s u b - p a r a l l e l l a m e l l a e o f p l a g i o c l a s e , o p t i c a l l y continuous, probably replacement p l a c e s , the o r t h o c l a s e g r a i n s show extremely  lamellae.  fine, straight  p a r a l l e l l a m i n a t i o n having s l i g h t l y d i f f e r e n t r e l i e f .  The  In  12 l a m e l l a e are arranged  i n one d i r e c t i o n throughout  the g r a i n ;  t h i s d i r e c t i o n i s not p a r a l l e l to t h a t o f the t w i n - l a m e l l a e o f the enclosed p l a g i o c l a s e g r a i n s , and forms an angle o f about degrees  w i t h the d i r e c t i o n o f t h e c o a r s e r i r r e g u l a r  lamellae.  T h i s f e a t u r e i s perhaps due t o an almost  30  plagioclase submicro-  s c o p i c e x s o l u t i o n o f a l b i t e , forming .a m i c r o - t o c r y p t o p e r t h i t e . The  corroded remnants o f enclosed m i n e r a l s become more abundant  towards the boundaries  o f the o r t h o c l a s e g r a i n , u n t i l the g r a i n  "peters o u t " i r r e g u l a r l y i n a normal g r a n i t i c t e x t u r e . From the more uniform p a r t s o f the s e c t i o n s and the hand-specimens i t appears of  t h a t the o l i g o c l a s e forms about 40%  the r o c k , the i n t e r s t i t i a l  ( o r i g i n a l ) o r t h o c l a s e about 20%,  and the l a r g e c r y s t a l s about 10%. B i o t i t e occurs i n dark brown f l a k e s up t o 4 mm but mostly s m a l l e r , forming perhaps 7% o f the rock. shows t h a t i t i s p a r t l y a l t e r e d to c h l o r i t e .  across  The s e c t i o n  About 2% o f  euhedral sphene, and t r a c e s of a p a t i t e , magnetite  and epidote  complete the m i n e r a l assemblage. T h i s rock, w e l l exposed along the t r a c t o r road  near  L i n d q u i s t Lake, shows a coarse blocky f r a c t u r e and a few narrow shears.  Some of the f r a c t u r e s are coated w i t h e p i d o t e , some  w i t h a p i n k i s h c r u s t of the c a l c i u m z e o l i t e - s t i l b i t e . 1-inch shear zone i n the g r a n o d i o r i t e i s completely  One  impregnated  w i t h massive p i n k i s h s t i l b i t e , i n which crushed fragments o f the rock a r e embedded.  13 (b)  Hornblende g r a n o d i o r i t e The  hornblende g r a n o d i o r i t e which forms the  bulk  of the n o r t h w e s t e r l y p a r t o f the i n t r u s i v e rocks on the i s a medium-grained l i g h t ture. and  I t outcrops  g r e e n i s h grey rock of g r a n i t i c  tex-  to the south and west of the mine camp,  the t h i c k Main v e i n l i e s  in it.  The  of p l a g i o c l a s e , q u a r t z , hornblende and by many v e i n l e t s o f epidote from 1 mm ferromagnesian  property  minerals  rock c o n s i s t s mainly  c h l o r i t e , and i s cut to about 10 mm  occur i n two ways:  wide.  as l i g h t  The  greenish  grey, i r r e g u l a r , r a t h e r i n d i s t i n c t spots about 3 - 4- mm  across,  which were probably b i o t i t e , nowreplaced by c h l o r i t e , and  as  dark g r e e n i s h b l a c k s h a r p l y d e f i n e d aggregates c o n s i s t i n g mainl y of hornblende. 5 mm  Both are i n places segregated  and more a c r o s s .  bleached  borders.  of s t i l b i t e .  t o form c l o t s  Some c h l o r i t e - e p i d o t e v e i n l e t s show  A few f r a c t u r e s are s l i c k e n s i d e d , w i t h t r a c e s  O r t h o c l a s e , sphene, p y r r h o t i t e and p y r i t e a r e  v i s i b l e w i t h a hand-lens. About 40% of the rock, as seen under a microscope, c o n s i s t s of p l a g i o c l a s e . s u b h e d r a l , now  T h i s forms l a r g e (2-3  mm)  crystals,  l a r g e l y a l t e r e d to a f i n e - g r a i n e d mixture  " w a t e r - c l e a r " a l b i t e , q u a r t z , s e r i c i t e , green b i o t i t e , and  epidote.  ation.  Only narrow rims are comparatively  These show twinning  lamellae o p t i c a l l y  those i n the a l t e r e d parts and  of  chlorite,  f r e e of a l t e r -  continuousvith  are c o n s i d e r e d p a r t of the  o r i g i n a l p l a g i o c l a s e c r y s t a l s r a t h e r than l a t e r a c c r e t i o n s . The  p l a g i o c l a s e composition,  determined from the l e s s  altered  rims, i s An 2 3 .  Many g r a i n s a r e s l i g h t l y sheared, showing  narrow bands of c a t a c l a s t i c or r e - c r y s t a l l i z e d a l b i t e ( ? ) . Quartz  occurs as i r r e g u l a r anhedral g r a i n s i n the  i n t e r s t i c e s o f the p l a g i o c l a s e c r y s t a l s , forming about 20% o f the rock. strain.  Almost a l l g r a i n s show u n d u l a t i n g e x t i n c t i o n due t o An unusual f e a t u r e i s the presence  of f i n e  inter-  growths o f quartz w i t h o r t h o c l a s e , not seen i n t h e other r o c k s , but very common i n the specimen examined. S l i g h t l y cloudy o r t h o c l a s e i s present as anhedral grains between p l a g i o c l a s e c r y s t a l s .  Some g r a i n s show t r a c e s  of p e r t h i t i c t e x t u r e ( s u b - p a r a l l e l i r r e g u l a r l a m e l l a e o f p l a g i o c l a s e arranged  at about 20 degrees  much l e s s conspicuous  to c l e a v a g e ) , but t h i s i s  than i n the other r o c k s , and the t o t a l  amount o f o r t h o c l a s e i s s m a l l e r , only about 20%. boundaries  are h i g h l y i r r e g u l a r .  The g r a i n  B i o t i t e and hornblende are  the c h i e f ferromagnesian m i n e r a l s , c h l o r i t e i s the main a l t e r ation mineral.  The b i o t i t e i s dark brownish  p l e o c h r o i c , i n d i c a t i n g an i r o n - r i c h v a r i e t y .  green, s t r o n g l y I t occurs as  minute s e r i c i t e - l i k e shreds and f l a k e s i n a l t e r e d c r y s t a l s , and as l a r g e r aggregates w i t h and surrounding hornblende.  plagioclase  of f i n e f l a k e s a s s o c i a t e d I t forms perhaps %  o f the  rock. Hornblende i s present i n c l u s t e r s of long p r i s m a t i c c r y s t a l s , commonly corroded by quartz and p l a g i o c l a s e , i n d i c a t i n g an e a r l y o r i g i n . pleochroic  I t i s dark b l u i s h green, s t r o n g l y  ( b l u i s h green t o g r e e n i s h y e l l o w ) the e x t i n c t i o n  angle Z*e  ranges from 15 t o 18 degrees.  T h i s probably a c t i n -  o l i t i c hornblende accounts f o r another % C h l o r i t e , g r e e n i s h and  of the  rock.  s l i g h t l y p l e o c h r o i c , occurs  s p a r s e l y as s m a l l shreds i n a l t e r e d p l a g i o c l a s e , and what l a r g e r masses a s s o c i a t e d w i t h hornblende. found mainly i n s m a l l i r r e g u l a r grains and p l a g i o c l a s e , i n hornblende c l u s t e r s and  as some-  Epidote  is  f i n e aggregates i n  i n narrow f r a c t u r e s .  S m a l l but well-developed c r y s t a l s of a p a t i t e occur i n the c l u s t e r s of ferromagnesian m i n e r a l s , carbonate are present s c a t t e r e d i n the (c)  and  i n s m a l l amounts.  shapeless g r a i n s of a Some f i n e magnetite i s  chlorite.  A l t e r a t i o n phases of hornblende The  types present  two  g r a n i t i c rocks  on the p r o p e r t y .  described The  granodiorite above are the main  hornblende g r a n o d i o r i t e  shows s e v e r a l a l t e r a t i o n phases: 1.  "Mine" g r a n o d i o r i t e :  The  "mine" g r a n o d i o r i t e  occurs mainly on the f o o t w a l l of a 10 f o o t wide m i n e r a l i z e d quartz  vein.  The  rock i s l i g h t grey, medium-grained, w i t h a  g r a n i t i c t e x t u r e and  a "bleached" appearance.  quartz, p l a g i o c l a s e , o r t h o c l a s e and greenish  spots  It consists  of  of f i n e - g r a i n e d  c h l o r i t e , which i s a l l t h a t remains of the f e r r o -  magnesian m i n e r a l s . under a hand l e n s .  A few  s m a l l aggregates of sphene are  F i n e grains  of c h a l c o p y r i t e and  s p a r s e l y disseminated i n the rock, and coated w i t h f i l m s of a white z e o l i t e  p y r i t e are  f r a c t u r e surfaces (laumontite).  visibl  are  About one which occurs  t h i r d of the rock i s formed of  i n anhedral  f r a c t u r e d and  g r a i n s up to 3 mm  showing u n d u l a t i n g  quartz,  a c r o s s , commonly-  e x t i n c t i o n due  to s t r a i n .  Some g r a i n s c o n t a i n a s m a l l f l a k e of muscovite i n the In s e v e r a l p l a c e s , s m a l l rounded grains o f quartz  center.  surrounded  by o r t h o c l a s e show o p t i c a l c o n t i n u i t y w i t h an adjacent g r a i n , suggesting  a l a t e r i n t r o d u c t i o n of the  quartz  orthoclase.  P l a g i o c l a s e comprises about 20% of the rock. shows subhedral  c r y s t a l s , now  clay minerals.  I t i s not zoned, and  to An 15.  It  s t r o n g l y a l t e r e d to s e r i c i t e i t s composition  and  i s close  I s o l a t e d embayed shreds of p l a g i o c l a s e occur  in  o r t h o c l a s e g r a i n s , showing a rough p a r a l l e l arrangement s i m i l a r to that described  previously.  Orthoclase  occurs  i n many anhedral  grains l-l<jr mm  a c r o s s , o n l y s l i g h t l y a l t e r e d to c l a y m i n e r a l s . numerous m i n u t e l y  i r r e g u l a r but  It  contains  generally p a r a l l e l lamellae  (about An 10-13) which give i t a p e r t h i t i c  plagioclase  These l a m e l l a e have d i f f e r e n t o r i e n t a t i o n i n d i f f e r e n t c l a s e g r a i n s , but w i t h i n any one continuous. and  They occur  g r a i n they are  of  texture. ortho-  optically  throughout the o r t h o c l a s e , even between  around i s o l a t e d remnants of quartz  f a s h i o n i n the o r t h o c l a s e .  The  grouped i n an  atoll-like  p l a g i o c l a s e l a m e l l a e are a l -  most u n a l t e r e d , which d i s t i n g u i s h e s them s h a r p l y from the euhedr a l plagioclase with i t s s e r i c i t i c a l t e r a t i o n . comprises now p o r t i o n was  about A-% of the rock, but  probably  much s m a l l e r .  The  orthoclase  its original  pro-  17 Narrow rims o f s e r i c i t e occur on the boundaries o r t h o c l a s e and quartz g r a i n s . 2%,  c o n s i s t s of c h l o r i t e .  A s m a l l p a r t of the r o c k , about  T h i s i s present as f r a y e d shapeless  masses, a p p a r e n t l y a l t e r a t i o n products of ferromagnesian als.  I t i s commonly a s s o c i a t e d w i t h f i n e l y  magnetite  miner-  disseminated  "dust", s u g g e s t i n g a breakdown of b i o t i t e .  masses of very f i n e - g r a i n e d g r e e n i s h a n t i g o r i t e the c h l o r i t e .  of  Small  (?) occur i n  A few t i n y g r a i n s of epidote and s e v e r a l patches  and narrow v e i n l e t s of a carbonate, which i s probably supergene, are present i n the rock. p y r i t e , c h a l c o p y r i t e and 2.  Sheared  I t a l s o c o n t a i n s sparse sphalerite.  silicified  g r a n o d i o r i t e : The  g r a n o d i o r i t e forms a band about 100 contact of the i n t r u s i v e .  disseminated  silicified  f e e t wide near the n o r t h e r n  I t i s a very l i g h t p i n k i s h grey,  medium - t o c o a r s e - g r a i n e d rock w i t h g r a n i t i c t e x t u r e , cons i s t i n g mainly of quartz and f e l d s p a r , and cut by numerous quartz v e i n l e t s from 1 mm minerals are almost  t o a few centimeters wide.  completely absent.  The  Dark  rock i s s t r o n g l y  f r a c t u r e d and sheared, and f i l m s of s e r i c i t e have developed the f r a c t u r e p l a n e s .  C r y s t a l s of p y r i t e up t o 3 mm  on  a c r o s s are  disseminated i n the rock, and brown l i m o n i t e s t a i n i s common on f r a c t u r e s . Under the microscope,  the rock i s seen t o c o n s i s t of  about 30% q u a r t z , 50% p l a g i o c l a s e , 20% o r t h o c l a s e and v e r y minor amount of s e r i c i t e .  I t s b r e c c i a t e d nature and mortar s t r u c t u r e  are evidence of s t r o n g mechanical  crushing.  The unzoned p l a g i o -  c l a s e i s h i g h l y ©trained, sheared and f r a c t u r e d . and displacement  o f the t w i n - l a m e l l a e are common.  i o n o f t h i s p l a g i o c l a s e , averaged about An 1 3 .  Bending The composit-  from 6 d e t e r m i n a t i o n s , i s  S e v e r a l l a r g e g r a i n s show a p e c u l i a r k i n d o f  mottled twinning, i n which s h o r t d i s c o n t i n u o u s  sub-parallel  twin l a m e l l a e are thickened and j o i n e d l a t e r a l l y t o produce a "hatching" e f f e c t .  The twin l a m e l l a e show o p t i c a l  and wavy e x t i n c t i o n .  T h i s i s p o s s i b l y secondary  continuity  twinning due o  to s t r e s s . Quartz  occurs i n anhedral i n t e r l o c k i n g g r a i n s , i s  f r a c t u r e d and shows u n d u l a t i n g e x t i n c t i o n .  In p a r t o f the  s e c t i o n the grains are c o a r s e , probably p a r t o f the o r i g i n a l rock, but g e n e r a l l y they a r e s m a l l , i n t e r l o c k i n g and concent r a t e d i n narrow bands t r a v e r s i n g the rock i n a l l d i r e c t i o n s . These are hydrothermal  veinlets.  Quartz  w i t h some o r t h o c l a s e and muscovite.  i s here a s s o c i a t e d  Orthoclase, p a r t l y  alter-  ed t o c l a y m i n e r a l s , i s a l s o found i n l a r g e anhedral g r a i n s that are p a r t o f the o r i g i n a l rock.  The d i s t i n c t i v e g r a i n s o f  p e r t h i t e w i t h p l a g i o c l a s e l a m e l l a e , common i n the previous types, are absent.  No ferromagnesian  minerals are present i n  the s e c t i o n examined. 3.  Gneissic biotite-granodiorite:  Gneissic b i o t i t e -  g r a n o d i o r i t e occurs i n a wide band on the hanging w a l l of "the Main v e i n .  The rock i s medium-grained, dark g r e e n i s h grey,  with a gneissic texture. spar and b i o t i t e .  I t c o n s i s t s mainly o f q u a r t z , f e l d -  B i o t i t e i s present i n an unusual amount,  19 about 25%,  segregated  i n i r r e g u l a r bands % - 3 mm wide.  Many-  s m a l l lenses ("augen") o f quartz i n f i n e - g r a i n e d m a t r i x suggest  that the t e x t u r e was produced  by s h e a r i n g .  Some spec-  imens show disseminated e p i d o t e and o r t h o c l a s e v e i n l e t s  with  epidote c r y s t a l s . I n t h i n - s e c t i o n , t h e rock shows f i n e - t o medium-grained g n e i s s i c t e x t u r e .  Bands o f f i n e l y crushed quartz and f e l d -  spar a l t e r n a t e w i t h s m a l l lenses of somewhat c o a r s e r i n t e r l o c k i n g quartz g r a i n s and w i t h i r r e g u l a r bands o f l a r g e f l a k e s of b i o t i t e . chroie.  The b i o t i t e i s brownish  green, s t r o n g l y p l e o -  The f l a k e s are mostly s t r a i g h t , but i n s e v e r a l p l a c e s  they are seen t o curve around p l a g i o c l a s e and quartz g r a i n s i n c l u d e d -in the bands.  The m i n e r a l a l s o occurs i n very  fine  f l a k e s of s e r i c i t i c h a b i t , disseminated between the main biotite  layers. Quartz  forms about 30% o f t h e rock.  Feldspar i s  s t r o n g l y a l t e r e d t o s e r i c i t e and c l a y m i n e r a l s , p l a g i o c l a s e more so than o r t h o c l a s e .  Only t r a c e s o f twinning remain i n  the p l a g i o c l a s e , the r e s t being l a r g e l y o b l i t e r a t e d by shearing.  D e t e r m i n a t i o n of composition by the Michel-Levy method  on four badly preserved g r a i n s i n d i c a t e d An 25.  Some o r t h o -  c l a s e g r a i n s c o n t a i n the u s u a l i r r e g u l a r l a m e l l a e o f p l a g i o c l a s e ; others are almost  c l e a r , only s l i g h t l y a l t e r e d .  l a t t e r occur w i t h quartz i n the crushed bands. o l i g o c l a s e each account  The  O r t h o c l a s e and  f o r about 20% o f the rock.  S m a l l euhedral t o subhedral c r y s t a l s o f a p a t i t e are  20 fairly  common i n the b i o t i t e bands, c u t t i n g s h a r p l y a c r o s s  biotite flakes.  Anhedral bands o f epidote a r e a l s o concen-  t r a t e d i n and near the b i o t i t e l a y e r s , w h i l e f i n e f l a k e s o f g r e e n i s h c h l o r i t e a r e disseminated 4.  i n the q u a r t z - f e l d s p a r bands.  Other a l t e r e d types:  The two remaining  are c l e a r l y the r e s u l t o f hydrothermal w i t h the f o r m a t i o n o f the v e i n s .  alteration  types  connected  They were not examined m i c r o -  scopically. One o f these occurs i n the immediate v i c i n i t y o f the Main v e i n and i n s m a l l g r a n i t i c i n c l u s i o n s i n the v e i n . rock i s l i g h t and  g r e e n i s h white, crumbly, has a rough s c h i s t o s i t y  c o n s i s t s o f q u a r t z , crushed f e l d s p a r and s e r i c i t e .  i s no t r a c e of the u s u a l mafic m i n e r a l s . f r a c t i o n of an i n c h wide cut the rock. but i r r e g u l a r boundaries by replacement. and specks  This  There  Quartz v e i n l e t s a They have f a i r l y  and are b e l i e v e d to have formed  sharp partly  S m a l l g r a i n s of s u l p h i d e s occur i n the v e i n s ,  o f c h l o r i t e were seen about 1 i n c h from the v e i n l e t s  i n some specimens. The  other h y d r o t h e r m a l l y a l t e r e d type was found  road cut about 1 m i l e east of the a d i t .  ina  There the rock i s cut  by s e v e r a l w e s t e r l y s t r i k i n g , s t e e p l y d i p p i n g quartz v e i n s up to  10 inches wide, c o n t a i n i n g masses o f f i n e - g r a i n e d magnetite,  minor p y r i t e and some c h a l c o p y r i t e . veins i s i n t e n s e l y a l t e r e d .  The rock between these  I t c o n s i s t s o f quartz and some  f e l d s p a r g r a i n s , crushed and sheared, embedded i n a very  fine-  g r a i n e d s o f t g r e e n i s h m a t r i x which c o n s i s t s probably o f c h l o r i t e .  21 In parts adjacent to the v e i n l e t s , and p a r t i c u l a r l y where the rock i s invaded by o f f s h o o t s of the quartz s t r i n g e r s , l i m o n i t e mixes w i t h the c h l o r i t i c m a t r i x c o l o r i n g i t brown.  The  bound-  ary between the green c h l o r i t i c and the brown l i m o n i t i c p a r t i s very i r r e g u l a r , but s h a r p l y d e f i n e d , i n places by a narrow rim of concentrated l i m o n i t e .  The m e t a l l i c minerals are  con-  f i n e d t o the quartz s t r i n g e r s . (d)  Mutual r e l a t i o n s U n f o r t u n a t e l y , the d i f f e r e n t rock types d e s c r i b e d  above have not been mapped i n d e t a i l , so t h a t t h e i r mutual r e l a t i o n s are not w e l l known; but from the specimens a v a i l a b l e f o r i n v e s t i g a t i o n i t appears  t h a t only two main types  are  distinguished. One ite.  d i s t i n c t i v e type i s the " p o r p h y r i t i c " g r a n o d i o r -  I t s f r e s h appearance and  the abundance of l a r g e euhedral  c r y s t a l s of o r t h o c l a s e are so c h a r a c t e r i s t i c of the rock i n the s o u t h e a s t e r n p a r t of the p r o p e r t y t h a t the rock was  mapped  as a separate u n i t on the e a r l y maps. The other main type i s the hornblende g r a n o d i o r i t e which forms the northwestern  p a r t of the Deer Horn i n t r u s i v e s .  I t s dark, g r e e n i s h , f i n e - g r a i n e d appearance c o n t r a s t s so s h a r p l y w i t h the coarse p i n k i s h rock t o the southwest t h a t the probability  of two  observer.  separate i n t r u s i o n s almost  f o r c e s i t s e l f on the  I t i s r e g r e t t a b l e t h a t t h e i r contact was  i n d e t a i l ; under the circumstances be e s t a b l i s h e d . The  not s t u d i e d  t h e i r age r e l a t i o n s  cannot  other types of i n t r u s i v e rocks l i e w i t h i n  22 the body o f the hornblende g r a n o d i o r i t e , and may r i v e d from i t by v a r i o u s The  t e c t o n i c and  of mafic minerals and  hydrothermal  and  the  d i f f e r s from i t by i t s s c a r c i t y  by i t s much more conspicuous replacement  p l a g i o c l a s e by o r t h o c l a s e .  to a t h i c k quartz  T h i s rock l i e s  formation.  These hydrothermal s o l u t i o n s were probably r e s p o n s i b l e  f o r the  removal of the mafic c o n s t i t u e n t s ; an extreme example o f  in  close  v e i n (the Main v e i n ) , which c e r t a i n l y r e q u i r e d  a great amount of hydrothermal a c t i v i t y f o r i t s  bleaching  de-  processes.  "mine g r a n o d i o r i t e " i n t e x t u r e resembles  hornblende g r a n o d i o r i t e , but  o f quartz  have been  are the crumbly s e r i c i t i z e d remnants of  this  granodiorite  the v e i n . A s i m i l a r o r i g i n seems l i k e l y f o r the  g r a n o d i o r i t e " on the n o r t h e r n  contact  "silicified  of the i n t r u s i v e .  This  crushed bleached rock, cut by innumerable s m a l l quartz s t r i n g e r s , l i e s up-dip from a narrow but p e r s i s t e n t quartz v e i n which marks a prominent and w e l l d e f i n e d shear zone underground. then represent  (70  tact may  (55  as i t passed from the  deg.  South) i n t o the o v e r l y i n g i n t r u s i v e rock.  s t r i n g e r s i n s t e a d of one  moval o f m a f i c c o n s t i t u e n t s solutions.  steeply  deg.S) s i l i c e o u s sediments through the f l a t t e r  e x p l a i n the f a i r l y wide s h a t t e r e d  egular  may  the upward c o n t i n u a t i o n of the shear, which  became l e s s s h a r p l y d e f i n e d dipping  It  con-  This  zone, the numerous i r r -  p e r s i s t e n t v e i n , and  the  re-  by the p e r c o l a t i n g hydrothermal  However, both the "mine" and  g r a n o d i o r i t e have a more s o d i c o l i g o & l a s e  the  "silicified"  than the normal horn-  blende g r a n o d i o r i t e , which i s d i f f i c u l t invoking and  complicated  t o e x p l a i n without  metasomatic processes r e q u i r i n g much more  b e t t e r evidence than that a v a i l a b l e at While these two  of mafic m i n e r a l s ,  types are c h a r a c t e r i z e d by t h e i r  lack  the g n e i s s i c b i o t i t e g r a n o d i o r i t e i s con-  spicuous by t h e i r abundance. the w e s t e r l y  present.  It lies  on the hanging-wall of  s t r i k i n g , n o r t h e r l y d i p p i n g Main v e i n at a d i s t -  ance of about 20 f e e t from the v e i n ; the i n t e r v e n i n g band i s s t r o n g l y hydrothermally a l t e r e d . i n t o non-gneissic  greenish  its rolls  and  ceded the formation  The  f o l i a t i o n i n the  p a r a l l e l to the Main v e i n , f o l l o w i n g  changes o f s t r i k e .  rock i s considered  not c l o s e l y  resembles the hornblende grano-  f a r t h e r south.  g n e i s s i c rock i s roughly  t h i s " rock grades  g r a n i t i c rock which was  s t u d i e d but which i n the f i e l d d i o r i t e outcropping  To the n o r t h ,  The  gneissic texture  of  the  to be the r e s u l t of the shearing which p r e of the Main v e i n and  l o c a l i z e d i t ; the  b i o t i t e appears r e - c r y s t a l l i z e d under d i r e c t i v e s t r e s s , and  the  crushed nature of the quartz  the  rock was for  and  f e l d s p a r a l s o suggest t h a t  formed under c a t a c l a s t i c metamorphism.  the i n c r e a s e of mafic c o n s t i t u e n t s  The  reason  i s uncertain.  The  "bleached" zone -around the Main v e i n dips g e n t l y to the the band of sheared s i l i c i f i e d dips s t e e p l y to the South. area that has  granodiorite described  These two  North,  above  zones i n t e r s e c t i n the  been i n v e s t i g a t e d at a depth of about 100  -  500  f e e t below s u r f a c e , thus i s o l a t i n g between them a wedge-like b l o c k of non-bleached g r a n o d i o r i t e .  An  i n c r e a s e of m a f i c  m i n e r a l s here may  be due  to r e d e p o s i t i o n  v i o u s l y removed from the Wo band may  perhaps be d e s c r i b e d One  of the mafics p r e -  bleached zones, and  the  enriched  as a "mafic f r o n t " .  of the most conspicuous f e a t u r e s  of both main  i n t r u s i v e types i s the i n t r o d u c t i o n o f p e r t h i t e , r e p l a c i n g e a r l i e r quartz and atism  feldspar.  But  s i n c e t h i s potash metasom-  a f f e c t s a l s o some sedimentary r o c k s ,  in detail  (S.S.Holland, Dept. of Mines, 1945;  government  L a n g i l l e , 1945;  as g r a n i t e , g r a n o d i o r i t e , quartz d i o r i t e and Joubin's s u r f a c e map  d i o r i t e ) , and  i n the l a t e r d r i l l - l o g s  into granodiorite  diorite  quartz d i o r i t e  s e c t i o n s , not  On  (the hornblende granothey were d i v i d e d by  the  quartz  However, examination of t h i n -  a v a i l a b l e to the previous workers, shows that  most of these names are i n c o r r e c t . i s d e s i r a b l e i n any initials  described  (the coarse  ( p i n k i s h , l e u c o c r a t i c ) and  (greenish, mesocratic).  1947;  Ney,  diorite.  they are marked as g r a n i t e  " p o r p h y r i t i c " type) and  2.  reports  o t h e r s ) , the i n t r u s i v e rocks have been v a r i o u s l y  writer  discussed  later. In s e v e r a l previous company and  and  i t w i l l be  As  some d i f f e r e n t i a t i o n  e v e n t u a l d e t a i l e d work on the  or numbers may  property,  be used to d i s t i n g u i s h the main  types.  Sedimentary Rocks The  sedimentary rocks on the property  are f i n e -  medium-grained rocks of s i l i c e o u s , f e l d s p a t h i c and composition.  to  carbonaceous  They form u n i t s from about 1 f o o t to s e v e r a l tens  o f f e e t t h i c k , but u s u a l l y not uniform i n composition.  In  n e a r l y every u n i t there a r e v a r i a t i o n s i n the p r o p o r t i o n s o f quartz and carbonaceous m a t e r i a l , which a r e u n f o r t u n a t e l y not s u f f i c i e n t l y d i s t i n c t i v e t o enable the t r a c i n g o f any such bed for a greater distance. The  f o l l o w i n g t a b l e o f rock u n i t s shows o n l y the p r e -  dominant types.  I t i s t o be understood  t h a t they are i n t e r -  bedded w i t h , and grade i n t o , t h i n n e r beds o f s l i g h t l y composition. order.  The rocks are l i s t e d i n t h e i r  different  stratigraphic  The s t r a t i g r a p h i c a l l y lowest known rock i s the carbon-  aceous greywacke which i s i n contact w i t h the hornblende on the d r i f t  diorite  l e v e l ; the s t r a t i g r a p h i c a l l y h i g h e s t and youngest  rock i s the f e l d s p a t h i c greywacke outcropping on the s u r f a c e . The  s t r u c t u r e of the sedimentary  a l a t e r chapter. the sedimentary  The hornblende  rocks w i l l be c o n s i d e r e d i n g r a n o d i o r i t e overlies part of  assemblage, so that some o f the rocks do not  outcrop, and are known o n l y from the a d i t and d r i l l - h o l e s . The  t a b l e i l l u s t r a t e s the t h i c k e s t s e c t i o n o f s e d i -  ments seen on the p r o p e r t y , and i s based near the western  on two d r i l l - h o l e s  end o f the a d i t and on t h e i r l i n e a r c o n t i n -  u a t i o n on the s u r f a c e .  26  SEDIMENTARY AND METAMORPHIC ROCK UNITS  (a)  Remarks  Thickness  Rock  over 500'  F e l d s p a t h i c greywacke Interformational breccia  l  1  Chiastolite schist  330'  Brown  argillite  370'  Black  argillite  75'  Feldspathic  Restricted i n l a t e r a l extent  On c o n t a c t w i t h the i n t r u s i o n on the s u r f a c e  155'  Contains beds o f s k a r n , b l a c k a r g i l l i t e and coarse arkose  over 6 5 '  On contact w i t h the i n t r u s i o n i n the a d i t elevation  quartzite  Carbonaceous greywacke  Upper contact not mapped  LOWER SEDIMENTARY CONTACT UNKNOWN  (b)  Carbonaceous greywacke T h i s rock, a d j a c e n t t o the i n t r u s i v e contact i n the  a d i t e l e v a t i o n , was logged as " b l a c k t u f f " .  I t i s a dark  grey  to b l a c k carbonaceous greywacke c o n s i s t i n g o f fragments o f q u a r t z , o r t h o c l a s e and some rock fragments.  They are commonly  v e r y s m a l l , only".rarely r e a c h i n g 4- mm i n diameter, to angular and s l i g h t l y f i n e - g r a i n e d mixture  elongated;  subangular  they are embedded i n a v e r y  o f carbonaceous matter  and s e r i c i t e .  The  27 p r o p o r t i o n s of fragments and m a t r i x , and of the  sericitic  and carbonaceous components of the m a t r i x vary w i d e l y  giving  the rock a l t e r n a t i v e l y a r a t h e r coarse fragmental and a f i n e r a r g i l l i t i c appearance.  F i n e g r a i n s of p y r r h o t i t e are  abundantly  disseminated i n the rock; l o c a l l y , lenses of massive p y r r h o t i t e s e v e r a l inches across and a few f e e t long are found.  Pyrite  i s somewhat l e s s common. Towards the n o r t h , the greywacke l o s e s most of i t s carbonaceous m a t e r i a l and grades spathic quartzite.  I t does not  i n t o coarse arkose and  feld-  outcrop.  Although the rock i s i n t r u d e d by the g r a n o d i o r i t e , it  does not show any s t r i k i n g e f f e c t s of contact metamorphism,  beyond the formation of s e r i c i t e and c o n v e r s i o n of the aceous matter  into graphite.  I t was  not examined  carbon-  microscop-  ically. (c)  Coarse  arkose  As the carbon content of the m a t r i x almost  disappears  and the p r o p o r t i o n of quartz and f e l d s p a r grains i n c r e a s e s c o n s i d e r a b l y , the rock grades  i n t o a coarse arkose.  The  ules of quartz and f e l d s p a r are subangular, from 1-3 mm are present i n about equal amounts, and embedded i n a grained s e r i c i t i c matrix.  granacross,  fine-  The rock i s l i g h t g r e e n i s h grey  and  has a p e c u l i a r g r a n u l a r appearance resembling the bleached g r a n o d i o r i t e near the v e i n s .  L o c a l l y i t contains lenses and  s t r e a k s of p y r r h o t i t e s i m i l a r to those i n the carbonaceous  greywacke.  I t was seen o n l y i n the a d i t where i t occurs  r a r e l y as narrow bands. In t h i n - s e c t i o n , some o f the o r t h o c l a s e g r a i n s are f r a c t u r e d and veined by s e r i c i t e , but f a i r l y f r e e from i n clusions.  These are c l e a r l y allochthonous and p a r t of the  o r i g i n a l sediment.  But many others c o n t a i n i r r e g u l a r  fragments  of quartz i n o p t i c a l c o n t i n u i t y w i t h adjacent quartz g r a i n s , and are p o s s i b l y autochthonous,  metasomatic.  A l l quartz and  most o f the o r t h o c l a s e g r a i n s show wavy e x t i n c t i o n due t o strain. (d)  The rock i s s t r o n g l y sheared, w i t h a mortar s t r u c t u r e . Feldspathic quartzite For a g r e a t e r p a r t o f i t s l e n g t h the a d i t runs  approx-  i m a t e l y p a r a l l e l t o a t h i c k bed o f f e l d s p a t h i c q u a r t z i t e which was mapped underground and logged as "greywacke". i t s s m a l l e r g r a i n - s i z e , t h i s rock appears coarse arkose.  Except f o r  v e r y s i m i l a r to the  I t i s d u l l grey i n c o l o r and c o n s i s t s of rounded  g r a i n s o f quartz and o r t h o c l a s e embedded i n a f i n e - g r a i n e d s i l i c e o u s and f e l d s p a t h i c m a t r i x , w i t h some carbonaceous The  matter.  fragments are mostly l e s s than 1 mm a c r o s s , although a few  are up t o 3 mm l o n g .  The rock i s very hard, compact and breaks  w i t h a jagged or almost  conchoidal fracture.  f i n e g r a i n s o f p y r r h o t i t e , abundantly  I t c o n t a i n s very  d i s t r i b u t e d i n the m a t r i x .  The Contact v e i n i n the a d i t l i e s  i n t h i s rock.  i s commonly accompanied by a 1 - 3 f o o t band of l i g h t  It  grey  s i l i c e o u s rock, i n places extending on both s i d e s of the v e i n ,  but mostly l y i n g at a s h o r t d i s t a n c e to one s i d e .  The  vein  favors the hanging-wall of the band i n the western p a r t of the a d i t ; to the east of a prominent clear.  The l i g h t  dyke the r e l a t i o n s are l e s s  c o l o r e d rock was  mapped as " a p l i t e " under-  ground, but i s merely a purer f e l d s p a t h i c q u a r t z i t e , w i t h most of  the carbonaceous  or  leached out.  content of the m a t r i x e i t h e r simply absent  The p o s s i b i l i t y of l e a c h i n g i s suggested by the fact that numerous t h i n v e i n l e t s of p y r r h o t i t e i n the grey show d i s t i n c t l y bleached and s i l i c i f i e d the l i g h t - c o l o r e d rock d e s c r i b e d above.  quartzite  boundaries s i m i l a r to However, as the  light  band l i e s at a s h o r t d i s t a n c e from the v e i n and the i n t e r v e n i n g rock has a normal grey c o l o r , the l i g h t l i e v e d to be of sedimentary The from 1 mm  c o l o r e d band i s be-  r a t h e r than hydrothermal  origin.  grey q u a r t z i t e i s cut by numerous narrow f r a c t u r e s  t o about  2 inches wide.  These are f i l l e d  mainly  w i t h q u a r t z , some c a l c i t e and g r a i n s o f p j i r r h o t i t e w i t h minor s p h a l e r i t e and galena.  In one s e c t i o n of the a d i t the f r a c t u r e s  commonly c o n t a i n a d e l i c a t e l y f i b r o u s pink Mn-bearing v a r i e t y of  zoisite  ( t h u l i t e ) , and r a r e l y s m a l l c r y s t a l s of p y r r h o t i t e . Near the western  t a i n s bands of massive  end of the d r i f t  the q u a r t z i t e  con-  e p i d o t e , brown garnet of 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 and q u a r t z , w i t h g r a d a t i o n a l boundaries. The lime s i l i c a t e bands l o c a l l y c a r r y disseminated and f i n e - g r a i n e d h e s s i t e . detail in a later  section.  scheelite  T h i s s k a r n w i l l be c o n s i d e r e d i n more  Beds of b l a c k a r g i l l i t e commonly i n the f e l d s p a t h i c (e)  Black As  the  from 2 to 1 0 f e e t t h i c k occur  quartzite.  argillite proportion  of quartz and  f e l d s p a r grains  i n i s h e s , the g r a i n - s i z e g r e a t l y decreases and content of the m a t r i x i n c r e a s e s , grades i n t o b l a c k a r g i l l i t e .  The  and  quartzite  t y p i c a l black a r g i l l i t e  a s i l k y l u s t e r on f r a c t u r e s .  t h i n lenses  the carbonaceous  the f e l d s p a t h i c  uniform, t h i n l y laminated rock w i t h p o o r l y t o s i t y and  dim-  developed  is a  schis-  Commonly i t c o n t a i n s  f i l m s of p y r r h o t i t e p a r a l l e l to the  bedding  planes. Although i t l i e s  c l o s e r to the  i n t r u s i v e contact  than  the band of the c h i a s t o l i t e s c h i s t mapped on the s u r f a c e , i t does not  contain  any  chiastolite crystals.  The  only  observable  e f f e c t of metamorphism i s the c o n v e r s i o n of the o r i g i n a l c a r bonaceous s h a l e The  into  main h o r i z o n  beds of f e l d s p a t h i c (f)  argillite. of b l a c k a r g i l l i t e  contains  several  quartzite.  Brown a r g i l l i t e ,  (metamorphosed)  This rock forms the h o r i z o n marker used i n c o r r e l a t i n g the sediments i n t e r s e c t e d by on the s u r f a c e . diorite.  On s u r f a c e  the d r i l l - h o l e s w i t h those mapped i t i s i n contact  w i t h the  grano-  I t i s g r e y i s h brown, brown weathering, compact, w i t h  only t r a c e s  of s c h i s t o s i t y and  a d u l l to s i l k y l u s t e r on  fractures.  31  It  i s c u t b y many n a r r o w v e i n l e t s f i l l e d w i t h q u a r t z ,  f e l d s p a r and a c t i n o l i t e . a short distance  some  Q u a r t z and f e l d s p a r p e n e t r a t e f o r  i n t o the walls of the f r a c t u r e s .  Locally,  t h e s e q u a r t z - a c t i n o l i t e b a n d s become a b u n d a n t a n d g i v e t h e rock a greenish appearance; t h i s  i s probably  " g r e e n s t o n e " mapped o n t h e s u r f a c e .  the o r i g i n a l  Narrow v e i n s  cutting  across  t h e q u a r t z - a c t i n o l i t e b a n d s c o n t a i n c r y s t a l s o f a d u l a r i a up t o 1 cm l o n g . In d r i l l - c o r e s rock  this  i s a f i n e - g r a i n e d brown  c o n t a i n i n g numerous s m a l l l e n s e s  and v e i n l e t s o f q u a r t z ,  s u r r o u n d e d o r b o r d e r e d by n a r r o w zones o f g r e e n i s h a c t i n o l i t e and c h l o r i t e . some  This  rock  biotitic  fine-grained  i s t h e "brown t u f f " o f  drill-logs. In t h i n - s e c t i o n , the rock c o n s i s t s o f a very  grained  assemblage o f q u a r t z , an undeterminable f e l d s p a r ,  brown b i o t i t e , a c t i n o l i t e c h l o r i t e and e p i d o t e . in this up  fine-  type of rock  t o 2 mm  long.  forming  minute r o s e t t e s , minor  One o f t h e many n a r r o w v e i n l e t s common contains  quartz  and c r y s t a l s o f a c t i n o l i t e  The b i o t i t e i s l e a c h e d  t h e v e i n l e t f o r a b o u t 1 mm;  only quartz  o u t on b o t h s i d e s o f and a c t i n o l i t e  rosettes  remain i n place. The  assemblage  quartz-feldspar-actinolite-biotite-  chlorite-epidote i s c h a r a c t e r i s t i c of the "greenschist" morphic f a c i e s , b i o t i t e - c h l o r i t e s u b f a c i e s .  According  T u r n e r a n d V e r h o o g e n , ( p . 469)> t h i s a s s e m b l a g e , w i t h  metato  some  m o d i f i c a t i o n s , may be t h e p r o d u c t o f l o w - g r a d e m e t a m o r p h i s m o f  a calcareous shale. of  T h i s i d e a i s supported by the  presence  bands of c a l c s i l i c a t e skarn interbedded w i t h the brown  argillite. (g)  Chiastolite  schist  The brown a r g i l l i t e  grades  over a s h o r t d i s t a n c e  i n t o a b l a c k , very f i n e - g r a i n e d s c h i s t o s e rock w i t h a g l o s s y l u s t e r , the c h i a s t o l i t e s c h i s t . of  conspicuous  var.  T h i s rock contains about  randomly o r i e n t e d metacrysts  c h i a s t o l i t e , 2 - 3 mm  long and Jj- - 1 mm  10$  of a n d a l u s i t e , wide.  The  mineral  shows the c h a r a c t e r i s t i c b l a c k cross of i m p u r i t i e s and i s mostly a l t e r e d to a white c l a y - l i k e substance. the metacrysts  In the  field  appear about 10 f e e t from both c o n t a c t s of the  band of the b l a c k s c h i s t and i n c r e a s e i n s i z e towards the center In and  t h i n - s e c t i o n , the rock shows about 10%  90% carbonaceous m a t r i x .  metacrysts  The m a t r i x c o n s i s t s of f i n e l y  d i v i d e d q u a r t z , s e r i c i t e and carbonaceous matter, which i s so abundant that i t obscures present.  any l e s s obvious minerals that may  The s e r i c i t e f l a k e s show a r o u g h l y p a r a l l e l  be  arrange-  ment which i s probably r e s p o n s i b l e f o r the s c h i s t o s i t y of the rock.  The  c h i a s t o l i t e metacrysts  cut s h a r p l y across the  c i t e f o l i a t i o n ; o n l y a s l i g h t bending observed to  i n places.  The  of the mica f l a k e s  seriwas  chiastolite i t s e l f is strongly altered  s e r i c i t e , only shreds of the o r i g i n a l m i n e r a l remain.  The  a l t e r a t i o n i s the r e s u l t of s u r f a c e weathering. The  rock i s a b l a c k s h a l e t h a t has undergone a  grade dynamothermal metamorphism to c h i a s t o l i t e s c h i s t .  lowThe  gradual disappearance  of the c h i a s t o l i t e metacrysts  towards the  contacts o f the b l a c k s c h i s t may be due t o a more s i l i c e o u s nature o f the g r a d a t i o n a l c o n t a c t s .  A similar  compositional  d i f f e r e n c e may a l s o e x p l a i n the l a c k of metamorphic m i n e r a l s i n the b l a c k a r g i l l i t e found underground and d e s c r i b e d above. T h i s rock p o s s i b l y d i d not have enough c l a y minerals i n the m a t r i x to supply the necessary A l f o r the f o r m a t i o n o f a n d a l u s i t e (h)  F e l d s p a t h i c greywacke The s t r a t i g r a p h i c a l l y h i g h e s t rock mapped on the  p r o p e r t y i s a f e l d s p a t h i c greywacke.  I t i s a grey, f i n e - g r a i n e d  fragmental rock c o n s i s t i n g o f q u a r t z , f e l d s p a r and b i o t i t e , w i t h a v e r y dense appearance, weathering  to a f i n e l y  pitted  buff-colored surface. In t h i n - s e c t i o n i t shows about 30% q u a r t z , 30% o r t h o c l a s e , 20% p l a g i o c l a s e and 20% m a t r i x .  The m a t r i x  consists  mainly o f b i o t i t e w i t h minor s e r i c i t e and carbonaceous The  quartz i s rounded t o subangular  and commonly r e c r y s t a l l i z e d  to a mosaic of s m a l l g r a i n s , showing s t r a i n - e f f e c t . c l a s e occurs i n subangular  matter.  Ortho-  grains p a r t l y a l t e r e d to s e r i c i t e .  The p l a g i o c l a s e i s a l b i t e , An 7.  I t occurs i n rounded g r a i n s ,  mostly c l e a r , w i t h w e l l - d e v e l o p e d t w i n n i n g .  B i o t i t e forms  s m a l l f l a k e s i n the m a t r i x , c u r v i n g around quartz g r a i n s .  The  rock has a very rough p a r a l l e l t e x t u r e , probably r e p r e s e n t i n g the o r i g i n a l bedding.  Some carbonaceous matter, v e r y  fine-  grained quartz and some f e l d s p a r make up the r e s t o f the m a t r i x .  A c c o r d i n g to P e t t i J o h n ' s c l a s s i f i c a t i o n of sandstones 3.  ( P e t t i j o h n , 1954), t h i s rock i s a f e l d s p a t h i c greywacke.  Dyke Rocks There are two types of dykes on the p r o p e r t y .  One  i s a l i g h t c o l o r e d n o r t h e r l y t r e n d i n g dyke w i t h a steep w e s t e r l y d i p , which cuts both the g r a n i t i c rocks and was  mapped as " f e l s i t e " and  a prominent f a u l t .  the sediments.  It  i s b e l i e v e d to mark the t r a c e of  The other type, logged as " t r a p " , s t r i k e s  w e s t e r l y , i s n e a r l y v e r t i c a l , cuts o n l y the i n t r u s i v e and i s not c o n s i d e r e d s t r u c t u r a l l y (a)  Albitite The  important.  ("Felsite")  l i g h t - c o l o r e d dyke, found both on the s u r f a c e and  underground, c o n s i s t s of a l b i t i t e .  The rock i s l i g h t  greenish  grey, f i n e - g r a i n e d , s l i g h t l y p o r p h y r i t i c i n i t s c h i l l e d phase.  The  groundmass c o n s i s t s mainly of s o d i c p l a g i o c l a s e  minor quartz and o r t h o c l a s e . c r y s t s up to 2 mm One it  border-  I t c o n t a i n s f e l d s p a r pheno-  long.  t h i n - s e c t i o n from a s u r f a c e outcrop was  examined,  shows that the groundmass p l a g i o c l a s e , forming about 85$  the rock, i s a l b i t e , An 2-4.  i s sparse  (5$).  of  I t occurs i n euhedral to subhedral  c r y s t a l s , i s cloudy and a l t e r e d to s e r i c i t e and Quartz  and  clay minerals.  I t forms i r r e g u l a r i n t e r s t i t i a l g r a i n s  i n the p l a g i o c l a s e groundmass. i n f i n e - g r a i n e d aggregates  Muscovite  (10%)  occurs commonly  and l a r g e r i s o l a t e d f l a k e s .  a t e , e p i d o t e , c h l o r i t e and hematite  Carbon-  (?) occur i n s m a l l amounts.  The  m i n e r a l composition o f t h i s rock resembles  s t r o n g l y that o f the a l b i t i t e d e s c r i b e d Cluanie  region,  Inverness, S c o t l a n d  p o s s i b l y have a s i m i l a r o r i g i n .  by Leedal from the  ( L e e d a l , 1952), and may  Leedal describes  a series of  changes i n the a l b i t i z a t i o n o f a rock of g r a n o d i o r i t i c comp o s i t i o n : 1.  Quartz was r e p l a c e d 3.  was a l b i t i z e d ;  by f e l d s p a r ;  cleavelandite replaced  f e l d s p a r s ; 4. i n some cases K - f e l d s p a r clase.  The f i r s t  Deer Horn; there (b)  2.  Plagioclase  quartz and the  p a r t l y replaced  two changes may have occurred  plagio-  i n the dyke at  i s no evidence f o r the l a s t two.  Hornblende L a t i t e ("trap") The  dark-colored  some d r i l l - h o l e s  dykes found on the s u r f a c e  and i n  c o n s i s t o f a f i n e - g r a i n e d dark g r e e n i s h - g r e y  rock, f i n e l y p o r p h y r i t i c , showing a f e l t e d mass o f n e e d l e - l i k e f e l d s p a r c r y s t a l s up t o 2 mm long and l e s s than \ mm wide, embedded i n a m i c r o c r y s t a l l i n e c h l o r i t i c groundmass.  Pyrite  and magnetite a r e f i n e l y disseminated i n the rock. A t h i n - s e c t i o n shows that the p l a g i o c l a s e forms about 40$  of the rock, hornblende and epidote account f o r about 10$,  and  the r e s t i s groundmass c o n s i s t i n g mainly o f c h l o r i t e and  l a t h - l i k e feldspar m i c r o l i t e s . The  p l a g i o c l a s e phenocrysts show imperfect  o b l i t e r a t e d by a l t e r a t i o n . An  No f r e e quartz was observed.  15-20.  albite.  twinning, i n p a r t  The f e l d s p a r i s s o d i c o l i g o c l a s e ,  I t i s t o some extent r e p l a c e d  by  "water-clear"  I t i s p o s s i b l e that the p l a g i o c l a s e was o r i g i n a l l y more  b a s i c , but was made s o d i c by a l a t e r metasomatic p r o c e s s .  36 On the b a s i s of the present composition the rock should be c l a s s i f i e d as "hornblende  latite".  But as there i s  some doubt as to i t s o r i g i n a l n a t u r e , the p u r e l y d e s c r i p t i v e term " t r a p " could be r e t a i n e d . 4.  Rocks a f f e c t e d by Metasomatism Some rocks found on the p r o p e r t y do not f i t r e a d i l y  i n t o the above c a t e g o r i e s , because they have been s t r o n g l y a f f e c t e d by contact phenomena, i n some cases pyrometasomatism, w i t h the p o s s i b l e i n t r o d u c t i o n o f i r o n and alumina, by the i n t r o d u c t i o n o f potassium the country r o c k s .  i n others  from the g r a n i t i c rocks  As they are r a t h e r i n t e r e s t i n g  into  petrologically  and i n some i n s t a n c e s e c o n o m i c a l l y , they w i l l be c o n s i d e r e d separately. (a)  E p i d o t e - garnet  skarn  Numerous bands o f epidote-garnet skarn occur i n the f e l d s p a t h i c q u a r t z i t e , i n the brown a r g i l l i t e and on the cont a c t o f brown a r g i l l i t e and c h i a s t o l i t e s c h i s t .  Drill-holes  show t h a t i t o c c u r s , although s p a r s e l y , throughout s e c t i o n o f sedimentary The the s u r f a c e .  the whole  rocks explored by d r i l l i n g .  skarn bands i n the a r g i l l i t e were mapped o n l y on They are 1 - 3  a t t i t u d e o f the sediments.  f e e t wide and f o l l o w the g e n e r a l The rock c o n s i s t s of massive e p i d o t e ,  garnet and quartz w i t h some c h l o r i t e .  The garnet and e p i d o t e  form s e p a r a t e p a r t s of the bands, the garnet being mostly  con-  c e n t r a t e d i n the center and the epidote on the o u t s i d e , but not  37  without  exceptions.  T h e i r mutual boundaries  are  irregular  but f a i r l y sharp; the t r a n s i t i o n a l zone i s l e s s than ^" wide. The  epidote i s the y e l l o w i s h green v a r i e t y " p i s t a c i t e " .  garnet belongs  to 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 .  the b a s i s o f i t s s p e c i f i c g r a v i t y i t l i e s  The  On  c l o s e r to the  a n d r a d i t e end, i t s probable composition being Gr 40 Ad  60.  Where the rock i s f r a c t u r e d , the f r a c t u r e s c o n t a i n w e l l - d e v e l o p e d c r y s t a l s of the m i n e r a l a d j o i n i n g the  fracture,  ( e i t h e r epidote or garnet but not b o t h ) , w i t h q u a r t z . may  suggest  minerals.  This  some m o b i l i z a t i o n and r e - d e p o s i t i o n of the s k a r n But many of the c r y s t a l - l i n e d f r a c t u r e s are vuggy  and f a i r l y open, so that the minerals may  have c r y s t a l l i z e d  i n a c a l c i t e v e i n l e t , from which the carbonate was  later  leached out.  Other f r a c t u r e s , from -§• t o 1" wide, are  with quartz.  Some of them c o n t a i n sparse s c h e e l i t e  filled  and  even more r a r e l y galena, w i t h s m a l l amounts of t e t r a d y m i t e . The  skarn i n the f e l d s p a t h i c q u a r t z i t e i s known o n l y  from underground exposures. of  the a d i t as a 2 -  bands nearby. to  I t was  seen i n the western p a r t  3 f o o t wide band, and  as much narrower  The u s u a l t h i c k n e s s v a r i e s from a few  inches  about 2 f e e t ; somewhat t h i c k e r bands were i n t e r s e c t e d i n  some of the  drill-holes..  The rock i s f i n e - g r a i n e d , compact, and c o n s i s t s of massive epidote w i t h l e s s e r amounts of garnet.  mainly  The s e p a r a t i o n  of the two minerals  i s not so c l e a r cut as i n the skarn i n the  brown a r g i l l i t e ; the minerals  are o f t e n mixed, or the garnet  occurs as s t r e a k s i n the e p i d o t e .  A t h i n - s e c t i o n o f one e p i d o t e  band shows that the rock contains a c o n s i d e r a b l e amount o f i n t e r s t i t i a l quartz.  E p i d o t e penetrates  i n t o the q u a r t z i t i c  w a l l - r o c k s i n s m a l l i r r e g u l a r g r a i n s , and disappears w i t h i n a short distance. calcite  In one p l a c e i n the d r i f t , a s m a l l lens o f  i n the skarn band contained well-developed  c r y s t a l s of  quartz and euhedral c r y s t a l s o f garnet up t o 1 cm a c r o s s , but t h i s type o f occurrence The  was q u i t e e x c e p t i o n a l .  rock i s cut by narrow v e i n l e t s o f quartz and c a l -  c i t e , commonly c o n t a i n i n g s p h a l e r i t e , galena and minor ides.  F i n e - g r a i n e d s p h a l e r i t e and h e s s i t e were found  inated e r r a t i c a l l y the d r i f t .  dissem-  i n the s k a r n band near the western end o f  S c h e e l i t e occurs  commonly - though i n s m a l l  q u a n t i t i e s - i n the skarn, mainly quartz  tellur-  connected w i t h f r a c t u r e s and  veinlets.  (b)  Quartz-wollastonite-garnet The  skarn  q u a r t z - w o l l a s t o n i t e - g a r n e t skarn i s known o n l y  from one d r i l l - h o l e , about 150 f e e t below the s u r f a c e , near the contact w i t h the g r a n o d i o r i t e . w i t h a sugary  I t i s fine-grained, granular,  t e x t u r e , and almost white w i t h brown s p o t s .  The  s p o t s , 2 - 4 mm a c r o s s , are garnet o f the g r o s s u l a r i t e - a n d r a dite series.  Quartz g r a i n s up t o 2 mm  i n diameter are embedded  i n the white matrix, which c o n s i s t s of f i n e - g r a i n e d f i b r o u s wollastonite.  The rock i s cut by a few narrow quartz  veinlets  with s i l i c i f i e d  b o r d e r s , and  porous m i n e r a l l i e s wollastonitic  In consist ite,  on  the  an i r r e g u l a r  zone o f a y e l l o w i s h  c o n t a c t of the s i l i c i f i e d  the  matrix.  thin-section,  the bulk o f the m a t r i x  o f a f e l t e d mass o f n e e d l e - l i k e c r y s t a l s  some i r r e g u l a r  grained  and  quartz.  ill-defined,  mineral i s probably altered  very  scapolite.  to  of w o l l a s t o n -  g r a i n s o f d i o p s i d e , m i n o r e p i d o t e and  The  t h e groundmass and  i s seen  fine-  fine-grained yellowish Orthoclase  penetrates  r e p l a c e s t o some e x t e n t many o f t h e  quartz  grains.  The probably  original  of quartz  m a g n e s i a n and  r o c k b e f o r e metamorphism c o n s i s t e d  g r a i n s embedded i n a m a t r i x  p e r h a p s somewhat s h a l y l i m e s t o n e ,  p o s s i b l y some f e l d s p a r . diorite,  the  morphosed  When i t was  quartz-magnesian limestone  grossularite-andradite series  altered  iron  i n the  to c h l o r i t e  produce the  by  developed  impure m a t r i x .  the l a t e r  greenish spots  slightly  quartz  i n t r u d e d by  the  and  grano-  a s s e m b l a g e was  to quartz-wollastonite-diopside.  aluminum and  of  A garnet  from the  i n the s i l i c i f i e d  of  the  calcium,  T h i s was  silica-bearing  meta-  probably  solutions  band.  The  to  calcite,  w h i c h i s commonly p r e s e n t  i n the rock, even i n the w o l l a s t o n -  ite  t o be  matrix,  solidation valent  i s considered of the  intrusive,  i n that area affected  e x t e n t , and  orthoclase partly  supergene.  the potassium  After  the  con-  metasomatism  pre-  t h e metamorphosed r o c k t o some r e p l a c e d some o f t h e  quartz g r a i n s .  40 Since the assemblage quartz-wollastonite-diopside is stable over a very wide range of temperature and  pressure  conditions, and since the rock, close to a large i n t r u s i v e body, can hardly be considered as a closed chemical system, the p h y s i c a l conditions during the formation of the skarn cannot be r e l i a b l y determined.  It i s only possible to state that  the temperature at which the rock was  formed was  probably  higher than 300° C, which i s the temperature necessary for the formation of wollastonite at 1 atm.  (after Danielsson, quoted  i n Mason, 1952, p. 221), and lower than 750° C, the maximum temperature of g r a n i t i c magma (Bowen, 1940).  Danielsson's  work modified Bowen's e a r l i e r reaction curve for the formation of wollastonite, and showed that i t may and s h i f t e d towards lower temperature.  be actually steeper (See Figure 1).  The probable range of composition of the o r i g i n a l rock, based on the r e l a t i v e proportions of the metamorphic minerals, i s given i n Figure 2. (c)  Perthite-quartz c a t a c l a s i t e A complex fragmental rock forms a band about 5 feet  wide approximately 20 feet north of the intrusive contact i n the eastern part of the d r i f t , adjacent and p a r a l l e l to the Contact vein.  The rock i s grey to greenish grey, spotty, and  consists of rounded to sub-angular  grains of quartz and f e l d -  spar embedded i n a s e r i c i t i c matrix.  The proportion of grains  to matrix and the size of the fragments varies i n d i f f e r e n t  Figure I.  A  300  A  reaction  curve  B  reaction  curve  C  reaction  curve  D  maximum  S  4  B DC  7  6  composition  f  o r t h e formation  6  temperature  diagrams 3  quartz,  Shaded -  o  f  for 2  granitic  of  original  diopside  (Bowen)  wollastonite of wollastonite  magma  (Danielsson) ( Bowen) .  (Bowen).  2.  Bowen's  reaction  CaSi0 *C0  Ca c a l c i t e , Di diopside, Wo  probable  of  for the formation  CaC0 + Si0 =* Q  I O O C ' C  9  3 for the formation  Figure  Paired  8  3  equation  No. 6 :  2  wollastonite, Fo forsterite,  composition of the  wollastonite  Pe penclase  skarn  specimens.  A common and conspicuous  the presence  f e a t u r e o f the rock i s  of o r t h o c l a s e p o r p h y r o b l a s t s , rounded or r e c t -  angular, forming about \ t o % o f the rock.  The l a r g e s t o f  them i s 0 . 7 " by 1.5"» w i t h sharp s t r a i g h t boundaries, are s m a l l e r and l e s s r e g u l a r .  Quartz  i n c l u d e d i n the p o r p h y r o b l a s t s .  others  g r a i n s are commonly  Narrow bands o f e p i d o t e occur  i n some specimens, and f i n e - g r a i n e d p y r r h o t i t e and p y r i t e are disseminated i n the rock i n a c o n s i d e r a b l e q u a n t i t y . t o s i t y i s i m p e r f e c t l y developed. ground as "porphyry",  Schis-  The rock was mapped under-  but i n view of i t s a p p a r e n t l y c a t a c l a s t i c  o r i g i n the name " c a t a c l a s i t e " i s more s u i t a b l e . A t h i n - s e c t i o n shows an i n e q u i g r a n u l a r assemblage o f quartz and o r t h o c l a s e g r a i n s i n a f i n e - g r a i n e d s e r i c i t i c m a t r i x w i t h some b i o t i t e .  The rock i s s t r o n g l y sheared and i n  places has a d i s t i n c t mortar t e x t u r e . The minerals.  o r t h o c l a s e i s p e r t h i t i c , cloudy, a l t e r e d t o c l a y  One l a r g e p o r p h y r o b l a s t i s broken i n t o s e v e r a l  coarse g r a i n s ; the c o n t a c t s between them a r e g e n e r a l l y s t r a i g h t , but m i n u t e l y i r r e g u l a r , s u t u r e - l i k e . K a r l s b a d twinning.  Some g r a i n s show coarse  Exsolution lamellae of a plagioclase with  v i s i b l e a l b i t e twinning are p r e s e n t , but not common. almost  a l l o r t h o c l a s e g r a i n s show t r a c e s o f extremely  However, fine  twinning and some p a r a l l e l l i n e s which may be v e r y f i n e perthitic  micro-  exsolution lamellae of a l b i t e . The  r e l a t i o n s of p e r t h i t e w i t h quartz are r a t h e r  complicated.  F o r the most p a r t , quartz  occurs  subangular, showing some s t r a i n - e f f e c t s . broken up on contact w i t h  i n large grains,  Many g r a i n s a r e  o r t h o c l a s e , and fragments of quartz  appear as rounded " i s l a n d s " i n the o r t h o c l a s e .  But i n other  parts o f the s e c t i o n quartz v e i n l e t s c u t the o r t h o c l a s e , and s e v e r a l euhedral  c r y s t a l s o f quartz  feldspar grain.  T h i s shows that at l e a s t a p a r t o f the quartz  i s l a t e r than the o r t h o c l a s e . minerals,  probably  occur  i n the middle o f a  Fine-grained  bands of both  c a t a c l a s t i c , appear between l a r g e r g r a i n s .  Another s e c t i o n was cut from a rock showing many grains of o r t h o c l a s e and q u a r t z , but no l a r g e T h i s rock i s o b v i o u s l y c a t a c l a s t i c .  porphyroblasts.  The l a r g e r fragments are  subangular, show s t r a i n - e f f e c t s and a r e commonly f r a c t u r e d , quartz more so than o r t h o c l a s e .  The appearance of the o r t h o -  c l a s e i s s i m i l a r t o that d e s c r i b e d above.  Quartz f i l l s  some  narrow f r a c t u r e s i n the f e l d s p a r . The porphyroblasts  fine-grained matrix  i n which the g r a i n s and  are embedded c o n s i s t s o f s e r i c i t e , minor b i o t i t e ,  very f i n e quartz  and some o r t h o c l a s e .  A carbonate i s f a i r l y  common i n the rock, p a r t i c u l a r l y i n i t s more crushed p a r t s and near s u l p h i d e g r a i n s .  Some of the euhedral  mentioned e a r l i e r are moulded on s u l p h i d e  quartz  crystals.  crystals • The s u l -  phides, v e r y common i n the rock, are mostly p y r r h o t i t e w i t h l e s s e r p y r i t e and sparse s p h a l e r i t e . I t i s almost i m p o s s i b l e  t o e s t a b l i s h d e f i n i t e l y the  o r i g i n a l nature of t h i s rock, but some s p e c u l a t i o n s  on i t s  mode o f f o r m a t i o n may be j u s t i f i e d . f e e t wide, approximately  I t forms a band about 5  2 0 f e e t n o r t h o f the i n t r u s i v e  t a c t i n the e a s t e r n p a r t o f the d r i f t ,  con-  i n the sedimentary  s e r i e s , adjacent t o and p a r a l l e l t o the Contact v e i n .  There-  f o r e i t i s probable that i t was o r i g i n a l l y a sedimentary The h i g h percentage siliceous  of quartz i n i t suggests  rock.  t h a t i t was o f a  nature. A f t e r the i n t r u s i o n o f the g r a n o d i o r i t e the rock was  permeated by the potassium-bearing  fluids  emanating from the  i n t r u s i v e , and l a r g e o r t h o c l a s e p o r p h y r o b l a s t s were formed i n it.  The a v a i l a b l e m a t e r i a l does not a l l o w any p r o f i t a b l e  s p e c u l a t i o n s on why t h i s rock was more f a v o r a b l e f o r t h e i r mation than o t h e r s . Contact shear  for-  The t e c t o n i c movements that produced the  (and thus l o c a l i z e d the l a t e r Contact  vein)  s h a t t e r e d the metasomatized rock and broke up the l a r g e porp h y r o b l a s t s , g i v i n g the rock i t s present c a t a c l a s t i c t e x t u r e . The  l a r g e i d i o b l a s t i c p o r p h y r o b l a s t mentioned above e i t h e r  escaped  s h a t t e r i n g f o r some unknown reason, or i s l a t e r  than  the s h e a r i n g , and shows perhaps the s i z e , i f not the shape, o f the p o r p h y r o b l a s t s before the s h e a r i n g . During the f o r m a t i o n o f the Contact v e i n , the sheared rock was penetrated by s o l u t i o n s b e a r i n g s i l i c a , sulphides.  These f i l l e d  carbonate and  some f r a c t u r e s i n the o r t h o c l a s e w i t h  quartz and deposited the s u l p h i d e s throughout  the rock.  The  r a r e euhedral quartz c r y s t a l s present i n the p o r p h y r o b l a s t s seem to have formed on the s u r f a c e of the s u l p h i d e g r a i n s , r e p l a c i n g the o r t h o c l a s e .  Thus, the " c a t a c l a s i t e " i s a complex matasomatic hydrothermally (d)  rock  altered.  A l k a l i metasomatism The w r i t e r b e l i e v e s that a l k a l i metasomatism was an  important  process  c o n t r i b u t i n g to the a l t e r a t i o n o f the rocks  along the igneous c o n t a c t .  The l a r g e , biotite-rimmed  ortho-  c l a s e g r a i n s i n the " p o r p h y r i t i c " g r a n o d i o r i t e , the i r r e g u l a r p e r t h i t i c g r a i n s i n the hornblende g r a n o d i o r i t e and i t s der i v a t i v e s , and the o r t h o c l a s e p o r p h y r o b l a s t s near the Contact  v e i n a r e the r e s u l t o f i n t r o d u c t i o n o f  potassium i n t o s o l i d The  i n the " c a t a c l a s i t e  rocks.  orthoclase porphyroblasts  i n a l l types  o f rocks  have many f e a t u r e s i n common: (a)  they a r e o f a l a r g e r s i z e than most other  minerals,  i n places c o n s p i c u o u s l y so. (b)  they a r e p e r t h i t i c , c o n t a i n i n g i r r e g u l a r narrow subp a r a l l e l lamellae of sodic p l a g i o c l a s e .  (c)  most o f them show very f i n e s t r a i g h t p a r a l l e l  lines  showing some d i f f e r e n c e i n r e l i e f and b i r e f r i n g e n c e . These may be almost sub-microscopic lamellae of a l b i t e .  exsolution  These f i n e l a m e l l a e do not  cross the l a r g e r i r r e g u l a r p l a g i o c l a s e l a m e l l a e , disappearing  f o r a s h o r t d i s t a n c e on both s i d e s o f  them. (d)  Some p o r p h y r o b l a s t s quartz  c o n t a i n c l u s t e r s o f rounded  grains i n o p t i c a l c o n t i n u i t y with a l a r g e r  4-5 quartz g r a i n o u t s i d e the o r t h o c l a s e .  This  suggests that the quartz i s r e p l a c e d by f e l d s p a r , (e)  most p o r p h y r o b l a s t s i r r e g u l a r "frayed'  1  i n the g r a n i t i c rock have v e r y boundaries,  with a r a p i d l y i n -  c r e a s i n g number o f i n c l u s i o n s towards the borders. The The  grains f i n a l l y "peter out" i n u n a l t e r e d  rock.  above f e a t u r e s may i n d i c a t e the common o r i g i n o f the o r t h o -  clase  porphyroblasts. The  f a c t that potassium metasomatism was a c t i v e along  the g r a n i t i c contact i s proved t o the w r i t e r ' s s a t i s f a c t i o n by the presence of the o r t h o c l a s e p o r p h y r o b l a s t s clastic  i n t h e now c a t a -  "porphyry", b e l i e v e d t o be a sedimentary rock.  difficult  It is  t o v i s u a l i z e an other than metasomatic o r i g i n f o r  these l a r g e f e l d s p a r grains and p a r t i c u l a r l y f o r the i d i o b l a s t i c porphyroblast  l-jjs- i n c h l o n g , mentioned above.  However, the  o r i g i n o f the o r t h o c l a s e g r a i n s and c r y s t a l s i n the g r a n o d i o r i t e i s less clear-cut. The  p o s s i b i l i t y that the whole body o f g r a n o d i o r i t e  i s o f metasomatic o r i g i n may be excluded  at the s t a r t .  The  presence o f the q u a r t z - w o l l a s t o n i t e - g a r n e t rock on the c o n t a c t proves t h a t the g r a n o d i o r i t e a r r i v e d i n a hot s t a t e and t h e r e f o r e probably The  as magma, no matter what i t s u l t i m a t e  origin.  problem then i s whether the o r t h o c l a s e g r a i n s i n the grano-  d i o r i t e a r e porphyroblasts that both types predominate.  or phenocrysts.  are r e p r e s e n t e d ,  The w r i t e r b e l i e v e s  but the p o r p h y r o b l a s t s  greatly  C a r e f u l examination  of specimens from the coarse  " p o r p h y r i t i c " g r a n o d i o r i t e shows that i t contains two of prominent o r t h o c l a s e forms:  one i s the subhedral  type w i t h numerous i n c l u s i o n s near i t s margins and surrounded is  by a narrow ( 1 - 2  mm)  types  pinkish commonly  zone of b i o t i t e .  The  euhedral, w i t h p e r f e c t l y s t r a i g h t sharp boundaries,  i n c l u s i o n s and no b i o t i t e rim.  other fewer  In t h i n - s e c t i o n , one of the  o l a t t e r type c r y s t a l s shows a number of s m a l l p l a g i o c l a s e i n c l u s i o n s i n the form of subhedral t o euhedral c r y s t a l s  arranged  i n a l i n e p a r a l l e l t o the (010) cleavage of the o r t h o c l a s e . The p l a g i o c l a s e c r y s t a l s are zoned i n a simple p r o g r e s s i v e  way,  the composition v a r y i n g from An 38 i n the i n n e r cores to An  20  i n the outer zone.  These are mantled by c l e a r untwinned  albite.  A metasomatic o r i g i n of t h i s o r t h o c l a s e c r y s t a l would not e x p l a i n the d i s t i n c t and r e g u l a r alignment plagioclase inclusions.  of the  The zoning of the p l a g i o c l a s e  crystals  i n d i c a t e s that they were not formed simply by a l a t e r r e p l a c e ment of the o r t h o c l a s e .  An e x p l a n a t i o n a c c e p t a b l e to the  w r i t e r i s that t h i s o r t h o c l a s e . c r y s t a l - along w i t h some others having the d i s t i n g u i s h i n g f e a t u r e s d e s c r i b e d above - i s a true phenocryst. it  During i t s c r y s t a l l i z a t i o n from a magmatic  enclosed e a r l i e r formed s m a l l c r y s t a l s of p l a g i o c l a s e  a l i g n e d them along one of i t s main c r y s t a l l o g r a p h i c  liquid and  directions.  The a l b i t e rims were formed l a t e r during e x s o l u t i o n o f the soda to form the f i n e p e r t h i t i c l a m e l l a e , or at a s t i l l  excess  later  s t a g e , together w i t h the c o a r s e r i r r e g u l a r l a m e l l a e of a l b i t e .  These were p o s s i b l y formed by l a t e replacement  of o r t h o c l a s e  by sodic  plagioclase. The other type o f o r t h o c l a s e c r y s t a l s and g r a i n s  shows some metasomatic f e a t u r e s , such as the corroded remnants of p a r t l y r e p l a c e d quartz g r a i n s and the b i o t i t e rim. b i o t i t e , at f i r s t  regularly distributed  throughout  The  the rock,  was d i s s o l v e d when the o r t h o c l a s e was p r e c i p i t a t e d , and removed outwards.  I t was then r e - d e p o s i t e d on the boundaries  newly formed f e l d s p a r g r a i n . i z e a continuous  o f the  I t i s perhaps p o s s i b l e t o v i s u a l -  process of s o l u t i o n and r e - p r e c i p i t a t i o n o f  the b i o t i t e as the o r t h o c l a s e c r y s t a l grew from a n u c l e u s , u n t i l f i n a l l y the growth stopped  and the b i o t i t e , d i s p l a c e d  from the area now occupied by the o r t h o c l a s e , was f i x e d as a narrow " b i o t i t e f r o n t " around the f e l d s p a r g r a i n .  Although no  exact measurements were made, t h i s hypothesis appears quantitatively.  plausible  By v i s u a l estimate, t h e amount o f b i o t i t e i n  the r i m i s approximately  equal to that which would have been  present i n the a r e a now occupied by o r t h o c l a s e , assuming d i s t r i b u t i o n of the mica throughout The  uniform  the rock.  apparent absence o f an analogous  zone o f quartz  and p l a g i o c l a s e , which had t o be removed together w i t h the b i o t i t e , does not pose any problem. i s conspicuous  and immediately  A narrow zone o f b i o t i t e  n o t i c e a b l e ; a s i m i l a r zone o f  quartz and p l a g i o c l a s e , which may w e l l be p r e s e n t , would be i n d i s t i n g u i s h a b l e from the normal c o n s t i t u e n t s o f the rock.  48 Thus, two  p r o c e s s e s , magmatic c r y s t a l l i z a t i o n  potassium metasomatism, account f o r a l l the l a r g e c r y s t a l s i n the p o r p h y r i t i c g r a n o d i o r i t e . granodiorite and  and  i t s d e r i v a t i v e s do not  the l a r g e o r t h o c l a s e  some of the t h i n - s e c t i o n s  grains  The  and  orthoclase  hornblende  c o n t a i n any  replacing quartz,  phenocrysts,  as seen i n  of t h i s type of rock, are  considered  to be metasomatic. A l k a l i metasomatism on the borders of a g r a n i t i c i n t r u s i v e , r e s u l t i n g i n the formation of f e l d s p a r porphyrob l a s t s i n the  i n t r u s i v e and  a very common phenomenon. (T&V,  1951  > P. 289)  about by f l u i d s  i n the a d j o i n i n g country r o c k s ,  is  Turner and Verhoogen's hypothesis  that the potash metasomatism i s brought  expelled  from s t i l l - c r y s t a l l i z i n g  granitic  magma i n the i n t e r i o r of the i n t r u s i o n , appears reasonable to the  writer.  CHAPTER  IV.  STRUCTURE  1.  G r a n i t i c Rocks As mentioned above, the Deer Horn p r o p e r t y l i e s  the contact  of g r a n i t i c rocks of the Coast Range b a t h o l i t h  sedimentary rocks of J u r a s s i c or Lower Cretaceous The types, the  g r a n i t i c rocks have been d i v i d e d  "porphyritic" granodiorite  granodiorite.  studied  does not  on the m i n e r a l i z a t i o n .  i n d e t a i l during  c i s e r e l a t i o n s of the two  be  i n t o two  For  hornblende  i s rather  direct  t h i s reason i t was  not  the  pre-  g r a n i t i c types are unknown.  But  the  had  i n his report  briefly  examined  of October 194-5 1.  dykes c u t t i n g both g r a n i t i c rocks and f r e s h - a p p e a r i n g g r a n i t e s , and  Fine-grained sediments; 2.  3. D i o r i t e s and  the  and  hornblende g r a n o d i o r i t e  l a t t e r rock i s the  oldest  and  divides dioritic Coarse  quartz d i o r i t e s .  (These correspond r e s p e c t i v e l y to the a l b i t i t e ,  "The  distant  the work on the p r o p e r t y , and  i n t r u s i v e s i n t o three c l a s s e s :  granodiorite  main  quoted.  E.G.Langille the  the  and  age.  appear to have any  o p i n i o n s of a company g e o l o g i s t who a r e a may  and  U n f o r t u n a t e l y , t h e i r contact  from the mine workings and influence  on  "porphyritic"  as used i n t h i s study.)  appears to be a s i l l ;  its  d i p i s only s l i g h t l y steeper than the h i l l - s i d e , i t s hanging w a l l has  been p a r t l y removed by e r o s i o n . "  ( L a n g i l l e i s not  quite  c e r t a i n whether t h i s i s a s i l l  or a dyke, but he c a l l s i t a  s i l l s i n c e i t conforms i n s t r i k e w i t h the H a z e l t o n beds.) "The  'quartz d i o r i t e ' i s i n t r u d e d by the coarse ' g r a n i t e , 1  which forms the l a r g e mass south of L i n d q u i s t Lake"  (across  the l a k e from Deer Horn.) The underground work on the p r o p e r t y completed  10  years a f t e r L a n g i l l e ' s i n v e s t i g a t i o n shows that h i s quartz d i o r i t e i s not a s i l l ,  because i t cuts across and  overlies  s e v e r a l s i l i c e o u s and carbonaceous beds, p r e v e n t i n g them from outcropping on the s u r f a c e .  However, h i s i d e a of a t a b u l a r  s t r u c t u r e f o r t h i s type of i n t r u s i v e rock may The to  each o t h e r .  be  correct.  two rock types have probably i n t r u s i v e  relations  They have been found t o a l t e r n a t e i n deeper  drill-holes  i n s e c t i o n s ranging from 20 t o 200 f e e t i n width,  with f a i r l y  sharp c o n t a c t s .  But s i n c e they have not been  c l o s e l y s t u d i e d d u r i n g the f i e l d work, t h e i r r e l a t i v e cannot 2.  be  age  determined.  Contact between G r a n i t i c and Sedimentary Rocks The  contact between the i n t r u s i v e rocks and  sediments i s f a i r l y sharp, except  f o r a band about 5 -  wide which u s u a l l y has a h y b r i d appearance.  The  I t dips i n g e n e r a l to the South at 50  but t h i s a t t i t u d e i s f a r from r e g u l a r , as was drilling  along the c o n t a c t .  10  feet  contact  s t r i k e s g e n e r a l l y E a s t , but w i t h l o c a l i r r e g u l a r i t i e s offsets.  the  -  55  and  fault  degrees,  e s t a b l i s h e d by  I t has p r o b a b l y many l o c a l r e -  v e r s a l s of d i p , o f f s h o o t s and nitude.  For  f a u l t o f f s e t s of v a r i o u s mag-  example, a v e r t i c a l diamond d r i l l - h o l e  i n the i n t r u s i v e penetrated through the contact and  210  entered  collared  f e e t of g r a n i t i c r o c k s , cut a l t e r e d sediments.  After  f e e t i t a g a i n i n t e r s e c t e d g r a n o d i o r i t e and continued 170  f e e t before i t was  stopped.  The  100  i n i t for  second i n t e r s e c t i o n here  represents  a t h i c k o f f s h o o t or a bulge.  o f f s e t was  encountered i n another d r i l l h o l e , i l l u s t r a t i n g  i r r e g u l a r nature 3.  of the  lateral the  contact.  Sedimentary Rocks The  i n v e s t i g a t i o n of the s t r u c t u r e of the sediments  i s r a t h e r complicated The  A probable  s i l i c e o u s and  by the l a c k of good h o r i z o n markers.  carbonaceous sediments encountered i n the  a d i t are interbedded,  a l t e r n a t e r a p i d l y and  u s u a l l y have  grad-  a t i o n a l c o n t a c t s , p r e s e n t i n g a p i c t u r e which - though complex i n s m a l l d e t a i l - i s r a t h e r monotonous i n g e n e r a l . good h o r i z o n marker was  found on the  T h i s i s the g r e e n i s h brown a r g i l l i t e mapped as  stone'' on s u r f a c e and T h i s bed was  logged  "green-  holes which may  an i n d i c a t i o n of i t s trend but w i l l not y i e l d i t s exact  b i t i t e dyke.  The  sur-  as "brown t u f f " i n d r i l l - h o l e s .  reached underground by two  tude, because the two  one  found, which can be used f o r c o r r e l a t i n g  the beds i n t e r s e c t e d underground w i t h those face.  Only  i n t e r s e c t i o n s a r e separated  dyke marks an important  movement i s b e l i e v e d to have o c c u r r e d .  give atti-  by the a l -  f a u l t along which a  The strike of the sediments on the surface varies locally from N65W to S80W, but in general i t is almost due West. The dip, as determined on surface, ranges from 40° South to 70° South.  Underground, the strike is again westerly, but the  dip becomes predominantly 60 - 70 degrees.  If the horizon  marker is reasonably continuous in the 500 feet between the drift elevation and its outcrop on the surface, without any major faulting, the generalized dip of the sediments would be about 60 - 70 degrees.  In some rocks, such as the chiastolite  schist, bedding is obscure and schistosity becomes prominent; but most of the rocks are not highly schistose.  The schis-  tosity is usually parallel or subparallel to the bedding. As mentioned, the above contacts are mostly gradational over distances varying from a. few inches to several feet. But one outcrop along the surface contact of the chiastolite schist and feldspathic greywacke was found to contain a narrow band (about 1 foot) of fragments of black a r g i l l i t e from a fraction of an inch to 1 inch across, embedded in a matrix of a lighter grey siltstone.  A thin-section shows that some of  the a r g i l l i t e fragments are "drawn out" by later shearing, but generally are angular, elongated, with sharp boundaries. The siltstone grades northward into the only slightly coarsergrained feldspathic greywacke.  The rock is then clearly an  interformatiorrbreccia, showing that the feldspathic greywacke overlies the andalusite schist.  As both rocks dip to the South  and the greywacke lies to the North of the schist, their s t r a t i graphic position is apparently reversed and the beds are overturned.  Although t h i s c o n c l u s i o n was reached  independently,  a l a t e r study of the company r e p o r t s showed that the i d e a was not new. writes:  I t was f i r s t  expressed  i n 194-7 by Chas. Ney, who  "In h o l e 22, many good examples o f bedding  that the top of the s u c c e s s i o n faced downward. from d r i l l - c o r e s r e q u i r e s v e r i f i c a t i o n .  indicated  This  evidence  I f c o r r e c t , i t means  that the whole a r e a i s p a r t o f an overturned f o l d . "  (Ney 1947)  T h i s mutually s u p p o r t i n g evidence shows that the sedimentary  rocks at the Deer Horn p r o p e r t y are part o f a  southern limb o f an overturned s y n c l i n e , whose a x i a l  plane  s t r i k e s w e s t e r l y and dips t o the South. 4.  The Veins The main o r e - b e a r i n g s t r u c t u r e s on the p r o p e r t y are  two p e r s i s t e n t quartz v e i n s , the "Main" and the "Contact", d i f f e r i n g i n a t t i t u d e , t h i c k n e s s , s t r u c t u r e and t o some extent i n t h e i r m i n e r a l content.  There are many other minor v e i n s  and s t r i n g e r s on the p r o p e r t y , but they have not been t r a c e d over any great d i s t a n c e s .  They a r e narrow and o n l y s p a r s e l y  d i s t r i b u t e d i n the country rocks and are not c o n s i d e r e d economically (a)  important. The Main V e i n The Main v e i n , from 5 t o 1 5 f e e t t h i c k ,  outcrops  i n t e r m i t t e n t l y f o r a t o t a l d i s t a n c e o f about 2000 f e e t . was the v e i n d i s c o v e r e d and staked by J o u b i n i n 1944.  This A great  part o f i t s l e n g t h i s covered by t a l u s and considerable  amount of t r e n c h i n g was  t h i n s o i l , and  a  necessary to e s t a b l i s h i t s  trend. From the s u r f a c e exposures and ment i t appears that the general surface  i s about N60W/30 NE.  p o s s i b l e due  and  trend of the v e i n near  A greater p r e c i s i o n i s h a r d l y  r o l l s , changes of s t r i k e , p i n c h i n g  ranging  swell-  from 50 to p o s s i b l y 250  From a c o n s i d e r a t i o n of the contour map  i t appears that  s t r i k e of the v e i n changes from w e s t e r l y to northwesterly minor r o l l s  near i t s western end,  feet. the  i n the e a s t e r n  part  possibly with several  i n between.  Its  dip near the s u r f a c e i s about 30 to 35  However, diamond d r i l l i n g i n d i c a t e s , and  that the v e i n changes dip underground. approaches the contact and  and  i s cut by a set of n o r t h e r l y s t r i k i n g f a u l t s which  displace i t for distances  NE.  the  to the f a c t that the v e i n i s f a r from s t r a i g h t ;  i t shows frequent ing,  underground develop-  degrees  the a d i t  confirms,  I t f l a t t e n s as i t  of the g r a n o d i o r i t e and  the  sediments,  f i n a l l y curves upward, forming a t r o u g h - l i k e s t r u c t u r e which  ends a g a i n s t  the Contact v e i n .  "trough", the upward extension  The  northeasterly  limb  of t h i s  of the v e i n , i s not a s i n g l e  continuous s t r u c t u r e , but r a t h e r a s e r i e s of i r r e g u l a r branching  s t r i n g e r s about 1 to 2 f e e t t h i c k , which o f t e n c a r r y  values.  The  greater p a r t of the Main v e i n , excepting  s e r i e s of s t r i n g e r s , l i e s i n the g r a n o d i o r i t e .  high  only  It w i l l  this  be  shown that t h i s s t r i n g e r zone, although u s u a l l y considered  an  i n t e g r a l p a r t of the Main v e i n s t r u c t u r e , may complicated  have a more  structural origin.  The  v e i n has  s t r o n g l y bleached  and  indefinite, highly irregular p a r t l y s i l i c i f i e d w a l l s , and  boundaries, contains  numerous i n c l u s i o n s of w a l l - r o c k near i t s c o n t a c t s .  It i s  b e l i e v e d to be a replacement v e i n . (b)  The  Contact V e i n on  Although the Contact v e i n does not o u t c r o p t h e  sur-  v  f a c e , i t s a t t i t u d e i s b e t t e r known, because i t was  followed  by  In the e a s t e r n part of the a d i t i t s t r i k e s N 87 W  the a d i t .  w i t h minor l o c a l v a r i a t i o n s , and  dips 60  to 73 degrees South.  A f t e r c r o s s i n g the a l b i t i t e dyke, i t s g e n e r a l s t r i k e changes to S 81 W and  the dip v a r i e s between 60 and  65 degrees.  The  Contact v e i n i s much narrower than the Main v e i n , being 6 to 12 inches wide i n the d r i f t . 2. R a i s e ,  and  f o r s h o r t d i s t a n c e s disappears  strong  In some p l a c e s , such as  i t narrows s t i l l more, forms 2" to 3"  No.  usually the  lenses,  a l t o g e t h e r , leaving only a  shear. For a g r e a t e r p a r t of i t s known l e n g t h the v e i n i s  w e l l - d e f i n e d , has  sharp sheared w a l l s and  the m e t a l l i c minerals the quartz. i n two gether,  and  ribbon s t r u c t u r e ;  are commonly deposited  Near the western end  on shear planes  of the a d i t the v e i n  splits  f i n a l l y i n s e v e r a l minor s t r i n g e r s which fuse  forming a quartz  lens about 3 f e e t t h i c k and  l o n g , w i t h i n d e f i n i t e boundaries and  almost barren*  in  to-  25 f e e t This  lens  narrows a g a i n towards the West and w a l l , 200  f e e t from the  end  of the d r i f t .  continues beyond that p o i n t ; the d r i f t  intersected  to the North of the (c)  J u n c t i o n of the Veins  The  junction  intersected first  3 inches t h i c k 9 f e e t  plunges about 14 degrees  easterly.  observed underground, where the zone  i n t e r s e c t i o n and  Both zones of s t r i n g e r s  are  they are  i n a r a i s e 320  also 75  and  w a l l r o c k s that  The  elevation.  i n t e r s e c t i o n obtained by p l o t t i n g the assuming N 60 W/25  NE  the Contact v e i n .  However, i f , as was  i t i s most  observed a t t i t u d e  s t r i n g e r Zone corresponds almost e x a c t l y two  to the  of  (Taking the s t r i n g e r s  i n the  the  the  of  veins on a s t e r e o n e t ,  f o r the Main v e i n and  N 8? W/70  S  for  commonly assumed,  the  are simply a c o n t i n u a t i o n of  the  have to plunge i n the as N 60 W/30  8W,  The  Contact  opposite d i r e c t i o n .  the Contact v e i n  plunge of t h e i r i n t e r s e c t i o n i s 18  d i r e c t i o n S 83 W.)  observed. to be  S,  the  direction  Main v e i n w i t h a reversed d i p , t h e i r j u n c t i o n w i t h the v e i n would n e c e s s a r i l y  of  so s i m i l a r i n t h e i r shape, a t t i -  connected.  southerly dipping s t r i n g e r s  was  f e e t west  f e e t above the d r i f t  tude, t h i c k n e s s , m i n e r a l i z a t i o n  N 87 W/70  of  of the v e i n s i s marked by a zone of  i n the a d i t and  l i k e l y that  shear p r o b a b l y  drift.  The  T h i s r e l a t i o n was  The  the  a d r i l l - h o l e near the west end  a quartz s t r i n g e r  quartz s t r i n g e r s , that  the  f i n a l l y disappears i n  w e s t e r l y plunge has  as  degrees not  been  B e s i d e s , some of the s t r i n g e r s , formerly c o n s i d e r e d "frayed"  s p l i t n o r t h e a s t e r n limb of the Main v e i n  trough, are now shown t o l i e i n the f o o t w a l l o f the v e i n , s t r u c t u r a l l y below the trough, so that a new i n t e r p r e t a t i o n of t h e i r s i g n i f i c a n c e i s necessary. (See F i g u r e 4 ) . (d)  The O r i g i n o f the Veins The  hornblende g r a n o d i o r i t e , host rock o f the Main  v e i n , i s s t r o n g l y sheared.  This  i s p a r t i c u l a r l y conspicuous  on the hanging w a l l of the v e i n , where the rock has a c q u i r e d prominent g n e i s s i c s t r u c t u r e .  a  This s t r u c t u r e becomes l e s s  d i s t i n c t with increasing distance  from the v e i n .  The f o l i a t i o n  i s g e n e r a l l y p a r a l l e l t o the a t t i t u d e o f the v e i n , fairly closely i t s irregularities.  following  This suggests that the  v e i n o r i g i n a t e d i n a shear zone. The  low angle of d i p of the Main v e i n suggests  the shear was probably a t h r u s t f a u l t .  that  Such a f a u l t may a l s o  e x p l a i n the change o f d i p w i t h depth, a f a c t e s t a b l i s h e d by drilling. and  The d i p f l a t t e n s and f i n a l l y reverses  the o r i g i n a l f a u l t c o n t a i n i n g  the g r a n o d i o r i t e  as the v e i n ,  i t , approaches the contact o f  and s i l i c e o u s sediments.  I t i s probable  that the competency o f the g r a n i t i c border zone and the s i l i c eous sediments was d i f f e r e n t from t h a t o f the main mass o f the granodiorite.  I f the border zone i s considered  as seems l i k e l y , the s h e a r i n g  angle i n i t would decrease and  the d i p o f the f a u l t would thus become f l a t t e r . p a r a l l e l t o the complementary shearing the opposite  more b r i t t l e ,  Fractures  plane, dipping  flatly i n  d i r e c t i o n , would develop at the same time; t h i s  may p o s s i b l y be the way i n which the f a u l t  terminates.  The curved t r o u g h - l i k e shape of the Main v e i n t h e r e f o r e be due  to a combination  of the o r i g i n a l  f l a t t e n i n g i n the more b r i t t l e border zone of the  may  thrust-fault, intrusive,  and i t s complementary s h e a r - p l a n e s . The Contact v e i n a l s o marks the plane of a s t r o n g fault.  A movement along t h i s f a u l t continued even a f t e r  the  f o r m a t i o n of the v e i n , as i s evident from the sheared nature o f the w a l l s and the r i b b o n s t r u c t u r e .  T h i s shear had  developed  approximately p a r a l l e l to the d i p of the bedding of the s e d i ments near the c o n t a c t .  S i n c e the d i p of the sediments  and o f  the contact w i t h the i n t r u s i v e d i v e r g e w i t h depth, the shear should i n c r e a s e i t s d i s t a n c e from the i n t r u s i v e i n the downdip d i r e c t i o n .  Up-dip,  the shear must approach  the c o n t a c t ,  i n t e r s e c t i t and pass i n t o the o v e r l y i n g g r a n o d i o r i t e . was  found t o be t r u e .  This  The sheared bleached g r a n o d i o r i t e near  the c o n t a c t , which c o n t a i n s numerous quartz v e i n l e t s and  was  mapped as " a p l i t e " on the s u r f a c e , i s considered to mark the upward e x t e n s i o n of the Contact  fault.  The steep d i p of the f a u l t suggests that i t was gravity fault.  A s u p p o r t i n g evidence may  be found i n the  a flat  s o u t h e r l y d i p of the quartz s t r i n g e r s i n the c o n t a c t zone, some of which cross the Main v e i n and appear i n the f o o t w a l l of the Main v e i n i n the d r i f t .  These s t r i n g e r s are c o n s i d e r e d  to mark the d i r e c t i o n of the f r a c t u r e cleavage r e l a t e d t o the Contact shear.  I f t h i s theory i s c o r r e c t , t h e i r a t t i t u d e i n -  d i c a t e s t h a t the f a u l t r e s p o n s i b l e f o r t h e i r f o r m a t i o n was  a  gravity fault.  A t h r u s t f a u l t i s u n l i k e l y f o r two  reasons:  the steep d i p , and the absence of n o r t h e r l y d i p p i n g f r a c t u r e cleavage which would be the necessary r e s u l t of a r e v e r s e type of movement. A c c e p t i n g the p o s s i b i l i t y that some of the s o u t h e r l y d i p p i n g high-grade  quartz s t r i n g e r s i n the contact zone occupy  cleavage f r a c t u r e s of the Contact f a u l t , i t remains explained why,  i f the j u n c t i o n of each i n d i v i d u a l  to be  cleavage  plane (with the given a t t i t u d e ) w i t h the Contact v e i n must plunge w e s t e r l y , the whole zone of s t r i n g e r s plunges  easterly.  I t i s c o n c e i v a b l e that the cleavage f r a c t u r e s veloped mostly along the i n t e r s e c t i o n of the two  faults i n  the p r e v i o u s l y sheared and p o s s i b l y p a r t l y s i l i c i f i e d R e c a l l i n g that the quartz s t r i n g e r s were formed by it  de-  belt.  replacement,  i s p o s s i b l e that the zone along the i n t e r s e c t i o n of the  f a u l t s was  sheared t w i c e , once i n c o n n e c t i o n w i t h the  r e v e r s e f a u l t of the Main v e i n , f o r the second e c t i o n w i t h the Contact f a u l t .  two  flat  time i n conn-  T h i s rendered i t much more  permeable f o r the l a t e r s i l i c a - b e a r i n g s o l u t i o n s , which d e p o s i t ed t h e i r l o a d i n the numerous i n t e r s e c t i n g f r a c t u r e s ,  partly  r e p l a c i n g the w a l l - r o c k and thus forming the i n t r i c a t e network of quartz s t r i n g e r s .  The v e i n l e t s terminate g r a d u a l l y a s h o r t  d i s t a n c e from the i n t e r s e c t i o n , as they pass from the h i g h l y sheared c o n t a c t zone i n t o the l e s s a f f e c t e d The  easternmost  granodiorite.  d e f i n i t e i n t e r s e c t i o n of the Contact  v e i n was  found i n a d r i l l - h o l e d r i l l e d almost due  entrance to the a d i t .  A surface  the a d i t i n t e r s e c t e d the contact  north  of  the  d r i l l - h o l e 2000 f e e t east of the i n t r u s i v e and  of  4-0 f e e t  o f a l t e r e d sediments ending i n the brown a r g i l l i t e , but  did  not  the  f i n d the Contact v e i n .  quartz-wollastonite ated p y r i t e , and  However, a s h o r t s e c t i o n of  skarn near the contact  gave some gold and  It i s possible therefore  s i l v e r values on assay.  that the contact  somewhere between the a d i t and  beyond the t e r m i n a t i o n  s i t u a t i o n was  v e i n pinches  t h i s d r i l l - h o l e , but  a l i z i n g s o l u t i o n s d i f f u s e d through the distance  c a r r i e s dissemin-  the miner-  crushed rock f o r some  of the a c t u a l v e i n .  observed i n the western p a r t of the  where s m a l l g r a i n s of galena were found i n an s k a r n , i n the s c h e e l i t e s l i d e , not  out  A similar  property,  epidote-garnet  connected w i t h any d e f i n i t e  vein. The  distance  between the s c h e e l i t e s l i d e and  d r i l l - h o l e which f a i l e d to f i n d a v e i n i n the contact about 4000 f e e t . slide has  The  the zone i s  ground to the west of the s c h e e l i t e  (which covers a s t r o n g  northerly-trending  shear zone)  never been t e s t e d by d r i l l i n g , so that no i n f o r m a t i o n  p o s s i b l e extension West i s a v a i l a b l e .  o f the Contact v e i n or Contact f a u l t t o But  the s p l i t t i n g  of the v e i n and  on  a  the  the  d i f f u s e nature of i t s western p a r t i n the d r i f t , where i t gets f a r t h e r from the g r a n i t i c c o n t a c t , may pinches out  i n d i c a t e that t h i s v e i n  somewhere i n the v i c i n i t y of the s c h e e l i t e s l i d e s .  I t i s of course e n t i r e l y p o s s i b l e that another f a u l t , w i t h or without a v e i n , takes over and  continues i n the same d i r e c t i o n .  The  a v a i l a b l e i n f o r m a t i o n i s not s u f f i c i e n t f o r  any s p e c u l a t i o n s on the t o t a l extent and manner of t e r m i n a t i o n o f the r e v e r s e f a u l t c o n t a i n i n g the Main v e i n . (e)  Summary In the w r i t e r ' s o p i n i o n , t h e two veins occupy two  prominent f a u l t s . was formed f i r s t ,  A flat  r e v e r s e f a u l t i n the g r a n o d i o r i t e  f l a t t e n i n g i n the more b r i t t l e border zone o f  the i n t r u s i v e and p e t e r i n g out i n a s e r i e s of complementary shears.  T h i s was f o l l o w e d by a steep  t i g h t normal f a u l t  passing from the i n t r u s i v e through the contact zone i n t o the sediments.  The two f a u l t s  converge towards the West.  of t h e i r i n t e r s e c t i o n was v e r y h i g h l y sheared. invaded  The zone  Both were l a t e r  by s i l i c a - b e a r i n g s o l u t i o n s which formed the two quartz  v e i n s , r e p l a c i n g the w a l l r o c k i n the now s t a t i c r e v e r s e  fault  and near the western end of the normal f a u l t , where the movement was at a minimum, but p e n e t r a t i n g o n l y s l i g h t l y i n t o the c e n t r a l p a r t s of the normal f a u l t where the movement during and a f t e r m i n e r a l i z a t i o n .  continued  Many i r r e g u l a r quartz  string-  e r s , w e l l m i n e r a l i z e d , were formed i n the badly sheared and thus h i g h l y permeable zone o f i n t e r s e c t i o n o f the two f a u l t s . The  south-dipping  veins found i n the f o o t w a l l o f the Main v e i n  are e i t h e r q u a r t z - f i l l e d  complementary shear f r a c t u r e s r e l a t e d  to the r e v e r s e f a u l t , or cleavage  f r a c t u r e s of the normal  fault. The  Contact  f a u l t pinches  out on both ends w i t h i n a  d i s t a n c e o f about 4000 f e e t .  Downdip, i t may p i n c h out as i t s  d i s t a n c e from the f l a t t e r d i p p i n g i n t r u s i v e contact i n c r e a s e s . T h i s would be analogous to i t s approaching the western end o f the d r i f t .  t e r m i n a t i o n near  A l t e r n a t i v e l y i t may pass  into  u n d e r l y i n g i n t r u s i v e such as was mentioned i n paragraph  two o f  t h i s c h a p t e r , and become merely an unmineralized shear  similar  to that i n the bleached  crushed  g r a n o d i o r i t e on the s u r f a c e .  In e i t h e r case there i s no reason t o expect t h a t i t w i l l t i n u e f o r a long d i s t a n c e downwards.  The high-grade  con-  stringer  zone i s a p p a r e n t l y l i m i t e d t o the i n t e r s e c t i o n o f the two v e i n s , one o f which i s known to terminate i n one d i r e c t i o n w h i l e the other i s n e i t h e r known nor expected end o f the f i r s t .  t o continue beyond the  T h e r e f o r e , i t i s reasonable  to assume t h a t  t h i s zone w i l l be l i m i t e d both h o r i z o n t a l l y and v e r t i c a l l y . I t should be emphasized that the above s p e c u l a t i o n s are o n l y hypotheses based on l i m i t e d evidence.  They agree w i t h  g i v e n data, c o r r e l a t e many o f them and are not c o n t r a d i c t e d by any known f a c t .  To prove these hypotheses i t would be necessary  to re-examine the a v a i l a b l e core, to u n i f y the nomenclature o f the rocks found  i n different d r i l l - l o g s , to r e - c l a s s i f y a l l  quartz i n t e r s e c t i o n s i n t o the four p r i n c i p a l c a t e g o r i e s  (Main  v e i n , I n t e r s e c t i o n zone, Contact v e i n and Other f r a c t u r e s ) to p l o t the d r i l l - h o l e s on t h i s b a s i s and thus t o determine the a c t u a l p o s i t i o n and extent o f the o r e - b e a r i n g s t r u c t u r e s . 5.  Post-mineral Faults P o s t - m i n e r a l f a u l t i n g i s widespread on the p r o p e r t y .  Only major f a u l t s showing s i g n i f i c a n t displacements mapped on the s u r f a c e . probably  F a u l t s of l e s s e r importance, though  common, are u s u a l l y d i f f i c u l t  t a l u s and  s o i l cover.  have been  The  t o recognize due  to the  underground workings show much b e t t e r  both the great number of f a u l t s and  the r e l a t i v e  insignific-  ance of most of them. The  s u r f a c e f a u l t s were mapped by F.R.Joubin, mainly  i n a b e l t along the i n t r u s i v e contact which contains the Main vein.  Most of the f a u l t s i n the western and c e n t r a l p a r t of  the p r o p e r t y s t r i k e n o r t h w e s t e r l y and n o r t h e r l y .  Northeasterly  s t r i k e i s more common i n the e a s t e r n p a r t though not exceptions. of 50 map  without  Almost a l l the f a u l t s d i p w e s t e r l y , i n the  to 60  degrees.  But  i n the absence of a more d e t a i l e d  and a good c o r r e l a t i o n of the f a u l t system w i t h a  g r a p h i c map, not appear  order  s t r u c t u r a l deductions  topo-  from the f a u l t p a t t e r n do  justified. In the a d i t , numerous f a u l t s cut the Contact  vein  and most of them d i s p l a c e i t , but g e n e r a l l y o n l y f o r a s h o r t distance.  A great m a j o r i t y of the displacements  order of a few  inches to one  f o o t , the maximum  of the Contact v e i n being 5 f e e t . probable  One  are i n the displacement  major e x c e p t i o n i s the  f a u l t marked by the a l b i t i t e dyke, which w i l l  considered  be  later. The  f a u l t s u s u a l l y s t r i k e between N30W and N30E, but  on the hanging-wall  of the a l b i t i t e dyke f a u l t s s t r i k i n g N30E  to N45E a r e common.  The dips a r e u s u a l l y s t e e p , the m a j o r i t y  i n the 60 t o 90 degree range and i n the w e s t e r l y (See F i g u r e  5).  The and  a d i t t r a v e r s e s only a s m a l l part o f the p r o p e r t y  i s a f f e c t e d only by three o f the major f a u l t s mapped on  the s u r f a c e . and  direction.  One i s a n o r t h e r l y s t r i k i n g f a u l t d i p p i n g  d i s p l a c i n g the Main v e i n i n the hanging-wall  to the North r e l a t i v e t o the f o o t w a l l .  50W  b l o c k 4-0 f e e t  Two c l o s e l y - s p a c e d  f a u l t s of s i m i l a r a t t i t u d e were found underground i n the area i n d i c a t e d by p r o j e c t i n g the s u r f a c e f a u l t t o the e l e v a t i o n o f the a d i t ; they d i s p l a c e the Contact and  v e i n 1 foot to the South  2 f e e t to the North r e s p e c t i v e l y .  Assuming that one o f  them i s the c o n t i n u a t i o n of the s u r f a c e f a u l t , the r e l a t i v e movement can be r e c o n s t r u c t e d .  Both f a u l t s i n d i c a t e a move-  ment i n the same d i r e c t i o n and of the same order of magnitude, about 15 t o 20 f e e t , the hanging-wall  b l o c k moving up and to  the North r e l a t i v e t o the f o o t w a l l b l o c k .  The p r o p o r t i o n o f  the s t r i k e - s l i p t o the d i p - s l i p component i s about Although t h i s i s not t o be regarded determination,  2:3.  as an exact  i t may give a f a i r i n d i c a t i o n o f the order o f  magnitude o f the movement on those i n the a d i t area.  Obviously,  f a u l t s a f f e c t i n g both veins  i t w i l l not h o l d t r u e f o r the  f a u l t s w i t h markedly g r e a t e r displacement of the p r o p e r t y .  i n the e a s t e r n p a r t  As mentioned b e f o r e , the Contact  v e i n under-  ground i s cut by numerous f a u l t s d i s p l a c i n g i t f o r a s h o r t distance.  I t i s suggested that very few o f them r e a c h the  Main v e i n ; most of them are only l o c a l f r a c t u r e s and the movement on them i s much s m a l l e r  than that on the major  faults.  A second type o f f a u l t i n g was a l s o i n d i c a t e d by the underground workings.  A prominent f a u l t was mapped on the  sur-  face i n the area o f the s c h e e l i t e s l i d e s , s t r i k i n g N20W, w i t h an undetermined d i p .  I t i s marked by a low g u l l y and was be-  l i e v e d t o have a c o n s i d e r a b l e  displacement.  But when the a d i t  approached the area below the s u r f a c e t r a c e o f the f a u l t , i t i n t e r s e c t e d i n s t e a d an 80 foot zone o f c l o s e l y spaced minor f a u l t s , d i s p l a c i n g the Contact v e i n from 3" t o 12" i n a s t e p l i k e horst-and-graben f a s h i o n , without changing i t s g e n e r a l trend. line.  The d r i f t d i d not even have t o d e v i a t e I f this fault-zone  from a s t r a i g h t  c o r r e l a t e s w i t h the f a u l t mapped on  the s u r f a c e , as i s almost c e r t a i n l y the c a s e , the zone s t r i k e s N17W and dips 84 degrees e a s t e r l y . The  t h i r d o f the major f r a c t u r e s reaching  from the  s u r f a c e t o the a d i t e l e v a t i o n i s a n o r t h e r l y t r e n d i n g containing  the a l b i t i t e dyke.  fault  This f r a c t u r e i n t e r r u p t s the  r e g u l a r t r e n d o f the Contact v e i n and d i s p l a c e s i t about 40 to 50 f e e t to the South on the hanging-wall o f the dyke r e l a t i v e to the f o o t w a l l . The surface  dyke, which can be w e l l c o r r e l a t e d w i t h i t s  exposure, s t r i k e s N26W and dips 70 SW.  I t i s about 20  feet thick on the surface and 12 feet in the adit.  Its  foot-  wall is straight and cuts sharply across the Contact vein, on its hanging-wall i t shows a few short apophyses and a sharp contact with the wall rocks.  The wall-rocks are the usual  assemblage of thin-bedded impure feldspathic quartzite and black a r g i l l i t e found in the d r i f t .  But while the rocks on  the footwall of the dyke are f a i r l y free from fractures, the hanging-wall rocks show a great number of faults and joints. These are concentrated in a zone which is 80 feet wide in the d r i f t , and strike predominantly easterly and northeasterly. Some of the fractures contain one-inch wide bands of gouge and some vugs with calcite and small crystals of laumontite, var. leonhardite (calcium zeolite).  Most show no apparent displace  ment; this of course may be difficult to determine in the monotonous assemblage of sediments present in that part of the drift. The Contact vein was encountered again 70 feet west and 27 feet south of the point where i t was cut off by the dyke.  It appears first in the south wall as a narrow mineral-  ized quartz stringer striking N 75 W, but within 15 feet i t widens to 4 inches and changes its strike to S 81 W, which i t maintains with only slight variations for the next 700 feet. This is a definite change from the strike to the east of the dyke, which is N 87 W. The position of the vein between the dyke and its re-appearance in the adit is not known; a hole was drilled to the South close to the hanging-wall of the dyke but had to be stopped due to a heavy flow of water before i t  reached the c r i t i c a l s e c t i o n . of  But the c u r v i n g o f the v e i n and  some more d i s t i n c t beds o f sediments suggests a drag on a  fault. The f r a c t u r e c o n t a i n i n g the dyke marks a l s o an imp o r t a n t change i n the a t t i t u d e o f the i n t r u s i v e c o n t a c t , from almost w e s t e r l y on the f o o t w a l l o f the dyke t o S75W on the The l a t t e r a t t i t u d e i s maintained f o r 800 f e e t  hanging w a l l . to the  the end of the explored s e c t i o n .  Whereas to the east o f  dyke the contact i s never more than 20 - 30 f e e t  distant  from the Contact v e i n , i t i n c r e a s e s i t s d i s t a n c e from about 40 f e e t on the hanging w a l l of the dyke t o 130 f e e t near the end of  the d r i f t  780 f e e t to the west.  Thus both the Contact v e i n  and the igneous c o n t a c t change s t r i k e on c r o s s i n g the dyke, r o t a t i n g 12 and 15 degrees r e s p e c t i v e l y , c o u n t e r - c l o c k w i s e . U n f o r t u n a t e l y the a v a i l a b l e d a t a are not s u f f i c i e n t t o s o l v e the  movement on the f a u l t . (a)  But s e v e r a l suggestions can be made.  S i n c e the Contact v e i n and the igneous c o n t a c t d i -  verge w i t h depth, t h e i r i n c r e a s i n g d i s t a n c e west of the dyke may mean that the western b l o c k has moved up, r e l a t i v e to the eastern block. (b)  Some r o t a t i o n a l movement has t o be p o s t u l a t e d t o  account f o r the change of s t r i k e and the suspected drag o f the vein. (c)  S i n c e the w a l l s of the dyke are not sheared, the dyke  was emplaced a f t e r the movement on the f a u l t had ceased.  With the e x c e p t i o n of the "dyke" f a u l t , the  post-  m i n e r a l f a u l t i n g on the p r o p e r t y i s o n l y of s m a l l importance i n the s t r u c t u r a l s e t t i n g . Main v e i n would present problem i s not l i k e l y  The major f a u l t s d i s p l a c i n g  some mining d i f f i c u l t i e s , but  to a r i s e f o r a c o n s i d e r a b l e  the  this  time.  CHAPTER V MINERALOGY OF THE  1.  Previous Work The  studied J.W.  VEINS  ore m i n e r a l s of the Deer Horn property  were  p r e v i o u s l y at the U n i v e r s i t y of B r i t i s h Columbia  Young (1946) and  i n more d e t a i l by A.C.  Taplin  Both worked on s e l e c t e d specimens from the s u r f a c e of the Main v e i n , but the  by  (1950). exposures  exact l o c a t i o n s of t h e i r specimens  are not known. In a d d i t i o n , the w r i t e r b r i e f l y examined a d d i t i o n a l sections 2.  The  from the Contact v e i n , obtained underground. Main V e i n The  are:  p y r i t e , arsenopyrite,  cosalite (Bi2Te3), was  minerals i d e n t i f i e d by T a p l i n i n the Main v e i n c h a l c o p y r i t e , s p h a l e r i t e , galena,  (Pb2Bi2S5), Tetradymite ( B i 2 T e S ), 2  altaite  (PbTe), h e s s i t e  identified tentatively.  can only add  (Ag2Te) and  tellurbismuth gold.  To t h i s e x c e l l e n t l i s t  s c h e e l i t e , p y r r h o t i t e and magnetite.  m i n e r a l i s common i n parts i n the Contact v e i n .  On  of the Main v e i n but  Argentite the The  writer latter  almost absent  the other hand, p y r r h o t i t e i s more  common or perhaps more conspicuous, i n the Contact v e i n . S c h e e l i t e was considered  seen i n s m a l l amounts underground and w i l l  l a t e r , i n c o n n e c t i o n w i t h the  be  "scheelite slides".  70 According  t o T a p l i n , p y r i t e was the e a r l i e s t  sul-  phide d e p o s i t e d , perhaps s i m u l t a n e o u s l y w i t h a r s e n o p y r i t e . Both are f r a c t u r e d , p y r i t e more than a r s e n o p y r i t e , and c h a l c o pyrite f i l l s  some of the f r a c t u r e s .  Both s p h a l e r i t e and c h a l c o -  p y r i t e are l a t e r than the i r o n m i n e r a l s , and probably s i m u l taneous. ite  Minute e x s o l u t i o n globules o f c h a l c o p y r i t e i n s p h a l e r -  were n o t i c e d .  C o s a l i t e and t e t r a d y m i t e are considered by  T a p l i n to be the next minerals i n the p a r a g e n e t i c sequence. C o s a l i t e was l a t e r p a r t l y r e p l a c e d by galena.  Tetradymite i s  b e l i e v e d t o be e a r l i e r than the l e a d s u l p h i d e , because i t had some d i r e c t i o n a l i n f l u e n c e on the replacement  o f c o s a l i t e by  galena and because i t c o n t a i n s sparse c r e n u l a t e d v e i n l e t s o f galena.  But as i t a l s o c o n t a i n s , i n other p l a c e s , i s o l a t e d  remnants of galena and h e s s i t e , i t may be i n part l a t e r .  The  "remnants" o f h e s s i t e i n t e t r a d y m i t e would i n d i c a t e t h a t the s i l v e r m i n e r a l i s e a r l i e r than the t e t r a d y m i t e , though i t s r e l a t i o n s t o the s u l p h i d e s are not known. were f o l l o w e d by t e l l u r b i s m u t h and a l t a i t e .  The e a r l y  tellurides  Native gold, a  r a r e c o n s t i t u e n t o f the o r e , was the l a s t m i n e r a l d e p o s i t e d . P y r r h o t i t e , found material, f i l l s  by the w r i t e r i n the Main v e i n  f r a c t u r e s i n magnetite and i s thus the l a t e r o f  the two; i t i s p a r t l y r e p l a c e d by c h a l c o p y r i t e , which shows that i t i s e a r l i e r than the copper m i n e r a l .  No good p a r a g e n e t i c  c r i t e r i o n f o r the age o f the magnetite was found  i n the s e c t -  ions s t u d i e d by the w r i t e r , but on l o g i c a l grounds magnetite is  c o n s i d e r e d t o be one o f the e a r l i e s t m i n e r a l s , i f not the  earliest.  71 Native g o l d , as determined by T a p l i n , occurs i n h e s s i t e , tetradymite,  t e l l u r b i s m u t h and galena.  T a p l i n be-  l i e v e s that much of the gold value comes from gold present i n the chemical  composition  o f the h e s s i t e .  gold content, r e p o r t e d i n analyses  However, the h i g h e s t  of h e s s i t e , does not exceed  5% (4.73%, r e p o r t e d i n Dana, p. 1 8 5 , 1944; 2.29%, r e p o r t e d by Thompson, 1949}  p. 3 5 6 ) .  Considering  the low percentage o f  h e s s i t e i n the o r e , i t i s d o u b t f u l whether t h i s a d d i t i o n a l source  of g o l d values  i s significant.  The w r i t e r i s i n c l i n e d  to b e l i e v e that n a t i v e g o l d , very f i n e l y disseminated  and per-  haps commonly a s s o c i a t e d w i t h h e s s i t e , i s r e s p o n s i b l e f o r the gold assays.  The higher v a l u e s , e r r a t i c a l l y d i s t r i b u t e d i n  p a r t s o f the quartz s t r i n g e r s i n the i n t e r s e c t i o n zone, c o u l d then be l o g i c a l l y explained by the presence of somewhat  coarser,  though s t i l l m i c r o s c o p i c , g r a i n s o f g o l d . 3.  The Contact As  Vein  the specimens from the Contact  v e i n which does  not outcrop were not a v a i l a b l e to T a p l i n , seven s e c t i o n s cut from t h i s v e i n were examined by the w r i t e r . The minerals  found i n the v e i n a r e p y r r h o t i t e , p y r i t e ,  s p h a l e r i t e , c h a l c o p y r i t e , galena, a l t a i t e and h e s s i t e .  Mag-  n e t i t e , a r s e n o p y r i t e , bismuth t e l l u r i d e s , c o s a l i t e and g o l d , present  i n T a p l i n ' s s e c t i o n s , were not seen i n the m a t e r i a l  from the Contact  vein.  f a r - r e a c h i n g conclusions  The w r i t e r does not wish to draw any from t h i s d i f f e r e n c e i n mineralogy.  While T a p l i n worked w i t h specimens s e l e c t e d f o r t h e i r  content  o f megascopic t e l l u r i d e s , the w r i t e r ' s specimens were  intended  to represent discrepancy possible.  an average sample of the v e i n m a t e r i a l , and due  But  a  to d i f f e r e n t methods of c o l l e c t i n g i s e n t i r e l y a few  f a c t s may  perhaps be  significant.  Magnetite, which i s common i n the Main v e i n , i s r a r e in  the Contact v e i n .  T h i s d i f f e r e n c e , together  w i t h the  pre-  dominance of p y r r h o t i t e i n the Contact v e i n , i s so conspicuous that i t was  used as a c r i t e r i o n f o r d i s t i n g u i s h i n g m a t e r i a l  from the two mineral in  veins  deposited,  in drill-cores.  I f magnetite was  first  as i s commonly the case, then i t s absence  the Contact v e i n may  mean that the d e p o s i t i o n of m i n e r a l s  there began l a t e r than i n the Main v e i n . ibility  the  i s that more sulphur was  An a l t e r n a t i v e poss-  a v a i l a b l e i n the sedimentary  environment of the Contact v e i n . The  absence of c o s a l i t e , tetradymite  and  tellurbismuth  a l l bismuth minerals - from the Contact v e i n s e c t i o n s may be s i g n i f i c a n t . and  Although the bismuth t e l l u r i d e s are abundant  conspicuous i n the s e c t i o n s  from the Main v e i n , no mega-  s c o p i c bismuth t e l l u r i d e s were found i n the Contact v e i n the w r i t e r , nor  by other  ground workings. Horn, wrote i n one  g e o l o g i s t s who  by  have seen the under-  S.L.Learning, the w r i t e r ' s predecessor at Deer of h i s r e p o r t s , d e s c r i b i n g the mineralogy  of the eastern p a r t of the a d i t : present,  also  " T e l l u r i d e s are  undoubtedly  as they have been noted i n the s u r f a c e showings of  Main v e i n .  However, none have been seen i n q u a n t i t y  large  the  enough f o r p o s i t i v e i d e n t i f i c a t i o n . have been r e p o r t e d by o t h e r s . "  H e s s i t e and t e t r a d y m i t e  I t may, o f course, be argued  that bismuth t e l l u r i d e s have simply been missed  underground  and that they are not present i n the p o l i s h e d s e c t i o n s s t u d i e d by the w r i t e r w h i l e o c c u r r i n g elsewhere  i n the Contact v e i n .  But i f they do occur t h e r e , the w r i t e r b e l i e v e s that they are present i n much s m a l l e r q u a n t i t i e s than those shown i n T a p l i n * s work on the Main v e i n . S i m i l a r l y , c o s a l i t e was not found  i n the Contact  v e i n , e i t h e r underground or i n the w r i t e r ' s p o l i s h e d s e c t i o n s . I f the three bismuth minerals are t r u l y absent  from the Contact  v e i n , t h i s may be due t o some unknown chemical f a c t o r which prevented  the p r e c i p i t a t i o n of bismuth compounds w h i l e  per-  m i t t i n g the d e p o s i t i o n o f o t h e r s , formed s i m u l t a n e o u s l y w i t h the bismuth minerals  elsewhere.  The amount o f a l t a i t e i s s m a l l , but the m i n e r a l i s commonly present i n the g a l e n a , as rounded g r a i n s from microns  a c r o s s , and as s t r a i g h t l a t h s about 5 - 1 0 microns  and up t o 70 microns noticed  5 t o 40  long.  wide  Although no r e g u l a r arrangement was  (the g r a i n s are too w i d e l y separated t o show any con-  spicuous a l i g n m e n t ) , the l a t h - l i k e and rounded shapes  suggest  the p o s s i b i l i t y o f e x s o l u t i o n . H e s s i t e i s very r a r e i n the s e c t i o n s from the Contact v e i n seen by the w r i t e r .  I t i s n e a r l y always a s s o c i a t e d w i t h  some o f the l a r g e r g r a i n s o f a l t a i t e , as i r r e g u l a r and l a t h l i k e forms.  The u s u a l arrangement shows a rounded g r a i n of  a l t a i t e surrounded by galena and cut by a l e s s r e g u l a r  and  somewhat elongated g r a i n of h e s s i t e , or c o n t a i n i n g a l a t h o f h e s s i t e on or near i t s boundary.  The h e s s i t e does not  extend  i n t o the galena, and there i s a s t r o n g p o s s i b i l i t y that i t was here exsolved from the g a l e n a , e i t h e r d i r e c t l y and s i m u l t a n eously w i t h a l t a i t e , or i n d i r e c t l y , from p r e v i o u s l y exsolved altaite.  In any case, the amount of h e s s i t e i n the ore i s v e r y  s m a l l , but may  be s u f f i c i e n t to account f o r the u s u a l low  s i l v e r assays i n t h i s type of o r e . A d e t a i l e d m i n e r a l o g r a p h i c study of a great number o f r e p r e s e n t a t i v e specimens  from both v e i n s would be necessary  to determine whether the d i f f e r e n c e s i n mineralogy between the two v e i n s are r e a l or apparent, and what i s t h e i r 4.  cause.  O r i g i n of the V e i n M i n e r a l s As both veins occur i n or near a l a r g e body o f  i n t r u s i v e g r a n i t i c rock, i t i s perhaps  unnecessary to l o o k be-  yond the i n t r u s i v e i t s e l f f o r a source of the m i n e r a l i z i n g fluids.  The v e i n s were probably formed by hydrothermal  sol-  utions e x p e l l e d from a c r y s t a l l i z i n g body o f g r a n o d i o r i t e . However, i t has been shown above that the Main v e i n was by replacement  i n a shear zone i n the hornblende  formed  granodiorite,  which means that t h i s part of the i n t r u s i v e must have been solid  before the a r r i v a l of the s i l i c a - b e a r i n g  fluids.  R e c a l l i n g that the two main g r a n i t i c types - horn-  75 blende g r a n o d i o r i t e  and " p o r p h y r i t i c " g r a n o d i o r i t e  - show mutual  i n t r u s i v e r e l a t i o n s , i t may be suggested that the m i n e r a l i z i n g f l u i d s came from the p o r p h y r i t i c g r a n o d i o r i t e , which had been intruded  i n t o the already s o l i d hornblende  granodiorite.  Although no d i r e c t evidence o f the l a t e r age o f the " p o r p h y r i t i c " rock i s a v a i l a b l e , the above e x p l a n a t i o n  appears more l o g i c a l  than an appeal t o the "hot i n t e r i o r " o f the i n t r u s i v e , which would be necessary i f i t i s p o s t u l a t e d granodiorite, containing two  granitic  types.  that the hornblende  the Main v e i n , was the l a t e r o f the  VANDEVEER  PARAGENETIC  DIAGRAMS  CHAPTER V I . TUNGSTEN MINERALIZATION  1.  Introduction S c h e e l i t e was  the m i n e r a l t h a t f i r s t a t t r a c t e d  e n t i o n t o the p r o p e r t y and l e d to i t s s t a k i n g i n 194-3.  attThe  m i n e r a l occurs i n both major v e i n s and i n the bands of c a l c silicates  interbedded w i t h the sediments.  " s c h e e l i t e s l i d e s " belong to the second  The  two  prominent  category.  The Deer Horn s c h e e l i t e i s pure white to honey y e l l o w i n c o l o r ; the y e l l o w type i s most common i n the Contact v e i n , the white  type i n the s k a r n .  the same b l u i s h white  However, both types f l u o r e s c e i n  c o l o r , without  a t r a c e of the y e l l o w i s h  f l u o r e s c e n c e c h a r a c t e r i s t i c f o r the molybdenum-rich members of the s c h e e l i t e - p o w e l l i t e s e r i e s , so t h a t the molybdenum content of the s c h e e l i t e i s c e r t a i n l y v e r y 2.  low.  S c h e e l i t e i n the Veins S c h e e l i t e occurs s p a r s e l y i n both v e i n s , though  i t was  not found  i n the quartz outcrops on the s u r f a c e .  I t was  seen i n the Main v e i n i n the a d i t as s m a l l g r a i n s a l i g n e d i n zones roughly p a r a l l e l to the d i p . w i t h the a i d of an u l t r a v i o l e t  I t can be r e c o g n i z e d o n l y  lamp and  i t s q u a n t i t y here i s  negligible. I t i s s l i g h t l y more abundant i n the Contact v e i n .  In  its  e a s t e r n p a r t , the Contact v e i n contains only sparse and  w i d e l y s c a t t e r e d grains of s c h e e l i t e from about in size.  mm  t o 3 mm  The q u a n t i t y of s c h e e l i t e i n c r e a s e s somewhat towards  the western end o f the a d i t , but even the best s e c t i o n s were not c o n s i d e r e d t o be commercial. narrow s t r e a k s concentrated comparatively i s thus almost  Here i t u s u a l l y occurs i n  i n those p a r t s of the v e i n t h a t are  free of m e t a l l i c sulphides.  As the s c h e e l i t e  i s o l a t e d from the other minerals  i n the v e i n ,  i t s p o s i t i o n i n the p a r a g e n e t i c sequence i s not known. 3.  S c h e e l i t e i n Skarn S c h e e l i t e was observed  i n the f i n e - g r a i n e d g a r n e t -  epidote rock, here d e s c r i b e d as "skarn", both on the s u r f a c e and  underground.  On the s u r f a c e i t appears  concentrated  mainly i n the area o f the two " s c h e e l i t e s l i d e s " i n the weste r n p a r t of the p r o p e r t y , but sparse s c h e e l i t e was found i n specimens c o l l e c t e d by the w r i t e r 1000 f e e t east o f the a d i t , over 2500 f e e t east o f the s l i d e s . and narrow ( 1 - 2  mm)  I t occurs as s m a l l g r a i n s  s t r i n g e r s l o c a t e d mostly  i n quartz v e i n -  l e t s and on f r a c t u r e s . The  occurrence  of s c h e e l i t e so f a r east of the  p r e v i o u s l y known s u r f a c e l o c a l i t i e s may mean t h a t the tungsten m i n e r a l i s s p a r s e l y , and probably e r r a t i c a l l y , throughout  distributed  the skarn bands, p a r t i c u l a r l y where they are  f r a c t u r e d and i n t e r s e c t e d by quartz s t r i n g e r s .  But as the bands  themselves are q u i t e narrow (from a few inches t o about 2 f e e t )  78 and w i d e l y separated, t h i s new  f a c t p r o b a b l y has no great  economic s i g n i f i c a n c e . 4.  The  "scheelite  slides"  The r e l a t i v e l y most conspicuous  occurrence  of  s c h e e l i t e on the s u r f a c e - and the one t h a t l e d t o the s t a k i n g of  the p r o p e r t y - i s i n two separate areas of t a l u s i n the  western  p a r t of the claim-group.  The two  t a l u s zones are  r e f e r r e d to as the " E a s t e r n " and the "Western" s c h e e l i t e Both c o n s i s t of fragments of brown a r g i l l i t e garnet s k a r n from •*j>-" to about 3 " mountain-side  epidote-  a c r o s s , c o v e r i n g the s t e e p  to a depth of about 1 f o o t .  The Western s l i d e has and i s 1600  and  slides.  an average width of 180  feet  f e e t l o n g , extending from the top of the r i d g e at  5740 f e e t down to 4700 feet„elevation.  B u r i e d i n the t a l u s  are  s e v e r a l s m a l l outcrops of brown a r g i l l i t e w i t h narrow quartz stringers, l o c a l l y carrying scheelite. are f a i r l y  Small s c h e e l i t e grains  common i n the t a l u s fragments,  particularly  those  d e r i v e d from bands of lime s i l i c a t e s , but most fragments are barren. The E a s t e r n s l i d e i s of lower grade and c o n s i d e r a b l y s m a l l e r , extending f o r about 500 f e e t downslope from a l a r g e outcrop of brown a r g i l l i t e w i t h s e v e r a l narrow skarn zones and a few  quartz s t r i n g e r s up to 4" wide.  separated by 300  - 400  Both s l i d e s  f e e t of b a r r e n black, s c h i s t .  are  The  area of the s c h e e l i t e s l i d e s l i e s  found by d e t a i l e d s u r f a c e mapping and  a s t r i d e a major by d r i l l i n g .  fault  As  the  tungsten m i n e r a l i z a t i o n appears r e s t r i c t e d to quartz v e i n l e t s and  f r a c t u r e s , the w r i t e r b e l i e v e s  introduced  that the s c h e e l i t e  was  i n t o the rocks by the s i l i c a - b e a r i n g s o l u t i o n s  have elsewhere formed the two  major v e i n s .  The  that  solutions  penetrated along f r a c t u r e s produced by p r e - m i n e r a l f a u l t i n g . The  c a l c - s i l i c a t e rocks were perhaps more f a v o r a b l e  to the  d e p o s i t i o n of s c h e e l i t e than the aluminous a r g i l l i t e ,  v  and  l o c a l i z e d most of the tungsten.  Later  t e c t o n i c movements  s t r o n g l y f r a c t u r e d the rocks and  enabled the s c h e e l i t e  bearing  fragments to accumulate under the i n f l u e n c e of g r a v i t y i n the present " s c h e e l i t e s l i d e s . " The may  then be  greater  concentration  the r e s u l t of  which i n c r e a s e d  of s c h e e l i t e i n t h i s area  (a) p r e - e x i s t i n g f r a c t u r e zone  the p e r m e a b i l i t y  of the rocks to the  i z i n g s o l u t i o n s , and  (b) p o s t - m i n e r a l f a u l t i n g and  which i s r e s p o n s i b l e  f o r the f o r m a t i o n of the  t a l u s zones.  mineral-  crushing  conspicuous  80 BIBLIOGRAPHY Bowen, N.L., P r o g r e s s i v e metamorphism o f s i l i c e o u s limestone and dolomite. Jour. Geol., V o l . 4 8 , No. 3 j 194-0. Bacon, W.R., H a r r i s o n Gold (Deer Horn Mines Ltd.) of Mines, B.C., Ann. Rept. 1 9 5 5 p. 2 5 .  Minister  D u f f e l l , S., W h i t e s a i l Map Area, B r i t i s h Columbia, Paper 5 2 - 2 1 , 1 9 5 2 .  G.S.C.  9  H o l l a n d , S.S., H a r r i s o n Gold, W h i t e s a i l Lake. M i n i s t e r o f Mines, B.C., Ann. Rept. 1944, p. 176. H a r r i s o n Gold, W h i t e s a i l Lake, B.C. Ann. Rept. 1945, p. 7 1 .  M i n i s t e r of Mines,  L a n g i l l e , E.G., H a r r i s o n Gold P r o p e r t y , Unpublished Pioneer Gold Mines.  report,  Learning, S.L. Underground geology, 4260 a d i t , Deer Horn Mines L t d . , Unpublished Report, May 1 9 5 5 . L e e d a l , G.P. , The C l u a n i e igneous i n t r u s i o n , Inverness and Ross. Quart. Jour. Geol. Soc. London, Dec. 1 9 5 2 ,  pp.  Mason, B., Ney,  C,  33-63.  "Principles  of Geochemistry".  Wiley, 1952.  G e o l o g i c a l o b s e r v a t i o n s , H a r r i s o n Gold P r o p e r t y , Unpublished r e p o r t , Jan. 1947.  Palache-Berman-Frondel, "Dana's System of Mineralogy", V o l . 1 . , 7 t h ed., W i l e y , 1944. Papezik, V.S. Summary Report on the Deer Horn Mine, Unp u b l i s h e d Report, November 1955. Pettijohn, F.J.,  C l a s s i f i c a t i o n " o f sandstones.  V o l . 6 2 , 1 9 5 4 , No. 4 , pp. 3 6 0 - 3 6 5 .  Jour. G e o l . ,  Robertson, F.,~and Vandeveer, P.L., A new diagrammatic scheme f o r p a r a g e n e t i c r e l a t i o n s of the ore m i n e r a l s . Econ. Geol. V o l . 4 7 , No. 1 . , pp. 1 0 1 - 1 0 5 . T a p l i n , A.C., Mineralogy of the H a r r i s o n Group, L i n d q u i s t B.C. Unpublished r e p o r t , U.B.C., 1950.  Lake,  Thompson, R.M., The t e l l u r i d e minerals and t h e i r occurrence i n Canada. Am. Min., V o l . 3 4 . , 1 9 4 9 , pp. 342-382. Turner, F . J . , and Verhoogen, J . , "Igneous and Metamorphic P e t r o l o g y " . McGraw-Hill, 1 9 5 1 .  P l a t e 2.  View from t h e a d i t towards the E a s t .  3.  Plate  Coarse p o r p h y r i t i c  4.  Chiastolite  granodiorite.  schist.  Plate 5.  O r t h o c l a s e porphyroblast i n perthite-quartz  P l a t e 6.  cataclasite.  O r t h o c l a s e porphyroblast i n p o r p h y r i t i c g r a n o d i o r i t e . Note the b i o t i t e rim.  Plate 7 .  Contact v e i n , low grade.  P l a t e 8.  Ribbon  Contact v e i n , high grade.  texture.  85-,  P l a t e 9.  Contact v e i n , x  204.  He h e s s i t e , A l a l t a i t e , Ga galena, Py p y r r h o t i t e .  P l a t e 10.  Main v e i n , x 65. He h e s s i t e , Te t e l l u r b i s m u t h , A l a l t a i t e .  

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