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A Genetic model for the Sustut copper deposit, North-Central British Columbia Wilton, Derek Harold Clement 1978

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A GENETIC MODEL FOR THE SUSTUT COPPER DEPOSIT, NORTH-CENTRAL BRITISH COLUMBIA by  DEREK HAROLD CLEMENT WILTON . S c . , Memorial U n i v e r s i t y o f Newfoundland, 1 9 7 6 A THESIS SUBMITTED  IN PARTIAL FULFILLMENT OF  THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department o f G e o l o g i c a l S c i e n c e s )  We a c c e p t t h i s t h e s i s as conforming to t h e r e q u i r e d s t a n d a r d  THE UNIVERSITY OF BRITISH COLUMBIA August, 1 9 7 8 ©  Derek H a r o l d Clement W i l t o n , 1 9 7 8  In p r e s e n t i n g t h i s t h e s i s  in p a r t i a l f u l f i l m e n t o f the requirements f o r  an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and I f u r t h e r agree t h a t p e r m i s s i o n  f o r e x t e n s i v e copying o f t h i s  that  study. thesis  f o r s c h o l a r l y purposes may be g r a n t e d by the Head o f my Department or by h i s  representatives.  It  i s understood that copying o r p u b l i c a t i o n  o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my written  permission.  Department o f  (&UjU><\  C c<>Q  S 1 vt-*vt-e S  The U n i v e r s i t y o f B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5  i i  Go my Sons, buy stout shoes, climb the mountains, search the valleys,  the deserts,  and the deep recesses this  the sea shores,  of the earth.  way and in no other will  . .for in  you arrive  knowledge of the nature and properties  at a of things.  P. Severinus  T h i s view from the East shows the Sustut massif.  The c l i f f s  Zone, and those Zone.  (circa 1778)  Copper  a t the r i g h t a r e p a r t o f the North  i n the m i d d l e are p a r t o f the South  The c i r q u e which c u t s the p r o p e r t y i n t o these  portions  can be seen between the two zones.  iii A GENETIC MODEL FOR THE SUSTUT COPPER DEPOSIT, NORTH-CENTRAL BRITISH COLUMBIA ABSTRACT Host o f the S u s t u t P r i n c e George,  Copper d e p o s i t , 230 m i l e s  (370 km) northwest  i s a 600 m t h i c k sequence o f v o l c a n i c l a s t i c r o c k s o f the upper  member o f the Upper T r i a s s i c Moosevale w e s t e r l y and d i p s about 20 degrees  Formation.  to the south.  This  unit strikes  Regional  (1977) was used f o r t h i s The Moosevale  local  discontinuous  Formation  i s m o s t l y conglomerate and v o l c a n i c b r e c c i a w i t h  and t h i n l a y e r s o f t u f f a c e o u s  rocks. Six  Fragments  f o r input  i n t o a computer.  types  volcanism.  core representing four  through the main o r e zones was done i n a r i g o r o u s  form d e s i g n e d  in the u n i t  r e l a t i v e l y common  are r e c o g n i z a b l e as being d e r i v e d from c o e v a l  Logging o f 10,000 f t o f diamond d r i l l sections  by Monger and  report.  are mainly b a s i c to intermediate v o l c a n i c rock. o f fragments  north-  stratigraphic  n o m e n c l a t u r e has been r a t h e r confused but the l a t e s t s u b d i v i s i o n Church  of  cross-  manner on a c o d i n g  Computer o u t p u t l e d t o a r a b i d  and q u a n t i t a t i v e e v a l u a t i o n o f the d a t a , p a r t i c u l a r l y as r e g a r d s c h a r a c t e r i s t i c s and i n t e r n a l s t r a t i g r a p h y o f the host u n i t . s u b d i v i s i o n w i t h i n the upper member o f the Moosevale  visual  to p h y s i c a l  No s t r a t i g r a p h i c  F o r m a t i o n was  accomplished.  T h i n s e c t i o n study o f metamorphic m i n e r a l assemblages i n d i c a t e d the metamorphic grade o f the host is higher  than t h a t  stratigraphic  levels  rocks  is p r e h n i t e - p u m p e l l y i t e f a c i e s . This  in o t h e r rocks o f the same l i t h o l o g i c u n i t s at  grade  equivalent  elsewhere.  C o p p e r - r i c h zones w i t h economic p o t e n t i a l appear to be r e s t r i c t e d t o the upper 60 m o f the 600 m t h i c k , c o a r s e - g r a i n e d t h e r e a r e minor o c c u r r e n c e s  throughout.  v o l c a n i c l a s t i c host,  though  The copper m i n e r a l s , m a i n l y c h a l c o c i t e ,  b o r n i t e , c h a l c o p y r i t e and n a t i v e c o p p e r , a r e e p i g e n e t i c and o c c u r w i t h q u a r t z , e p i d o t e , p r e h n i t e , and c a r b o n a t e  i n v e i n l e t s and i n t a b u l a r zones p a r a l l e l  to  bedding. are  Pyritized  rock  negligible in total  space f i l l i n g ;  b o t h open  variable  degrees  apparent  i n some t a b u l a r  core  volume  of mineralized  space f i l l i n g  in tabular  show n e i t h e r  mineralized  zones.  zones about a n a t i v e  were o p e r a t i v e  of  a zonal  from margin to  a n d i n some c a s e s t h e r e  been  statistical1y  been.compared correlation  o f copper minerals  i n d i c a t i n g a high  mineralization. represented  with  These  minerals  geothermometry,  distribution  i s no  semblance  with  v o l c a n i c l a s t i c rocks  and n o n - m e t a l l i c in veins  the Moosevale  are  c u t by v e i n s The  textures,  and r e l a t i v e l y  porous  phase  prior to  pile are  c o p p e r z o n e s and l o c a l permeable  were p r e c i p i t a t e d tabular  r e l a t i o n s a n d an  i s consistent with  Age o f m i n e r a l i z a t i o n  cut  have  have s e d i m e n t a r y  permeability  minerals  - 300*C i n d i c a t e d by g a n g u e m i n e r a l  from below.  that  metamorphic  based on s u l p h i d e  channelways  to  copper zones.  of  tabular  amenable  copper m i n e r a l i z a t i o n and i l l u s t r a t e t h e  to intergrowth  interconnected  particularly  size,  q u a n t i f i e d t e x t u r a l parameters  origin  The  been  p o r o s i t y and p r o b a b l y a h i g h  t h e same s o l u t i o n s , b o t h  250  tabular  as s o r t i n g , g r a i n  These, p o r o u s u n i t s w i t h i n t h e v o l c a n i c l a s t i c  by t h e t a b u l a r  Copper  (such  f o u n d t o have  o c c u r r e n c e o f copper m i n e r a l s .  limited  nor a p e r f e c t l y symmetric  ranges o f t e x t u r a l parameters  o f t h e h o s t rock, have  features  Most  d i s t r i b u t i o n of ore minerals.  Specific etc.)  to  A c r u d e . v e r t i c a l zoning i s  z o n e s , where t h e i d e a l i z e d sequence  copper core,  Veins  a n d f o r m e d m a i n l y by o p e n  and metasomatism  t h e c o m p l e t e sequence  of  from  rock  zones.  i s : p y r i t e - c h a l c o p y r i t e - b o r n i t e - c h a l c o c i t e - n a t i v e copper.  zones  the  s u r r o u n d s some c o p p e r - b e a r i n g t a b u l a r  zones. A  interpreted  temperatures of deposition  assemblages. s e t s o f v e i n l e t s appear  to ore fluids  is uncertain  Formation s t r a t i g r a p h i c a l l y  that  presumably were  but v e r t i c a l  above  t o have  m a f i c dykes  t h e main m i n e r a l i z e d  formed  derived that zones  and t h u s a r e p r e m i n e r a l i z a t i o n .  upward  f l o w o f t h e hot s o l u t i o n s w i t h i n a s t r u c t u r a l zone  defined  V  now by swarms o f C u - b e a r i n g resulted  in a l o c a l  v e i n l e t s produced a c o n f i n e d geothermal  node o f p r e h n i t e - p u m p e l 1 y i t e  f a c i e s . metamorphism and c o n -  c o m i t t e n t development o f copper m i n e r a l s and p y r i t e . stitial  ore f l u i d represent  T a b u l a r zones w i t h  studies  development o f o r e m i n e r a l s  and the o b s e r v e d  inter-  l o c i o f f 1 u i d - w a l 1 rock r e a c t i o n and o r e - m i n e r a l  may be a t t r i b u t e d i n - p a r t to d i f f u s i o n outward from these Sequential  high t h a t  zonal  as  loci.  i n d i c a t e d by  d i s t r i b u t i o n requires  paragenetic  an o r e f l u i d i n i t i a l l y  rock.  n a t i v e copper f o l l o w e d " s u c c e s s i v e l y  by c h a l c o c i t e , b o r n i t e , c h a l c o p y r i t e and  i n the ore s o l u t i o n n e a r i n g  r e a c t i o n t o produce  more  o x i d i z i n g than the b a s a l t i c c o u n t r y  f i n a l l y pyrite, resulted  Continued  zoning  e q u i l i b r i u m w i t h the  first  host.  vi TABLE OF CONTENTS Page FRONT I SP I ECE . . . J  . .................................................. i i :  ABSTRACT . .  iii  TABLE OF CONTENTS . .  ..vi  LIST OF FIGURES  >.x  LIST OF TABLES „  .  .  LIST OF APPENDICES ACKNOWLEDGEMENTS CHAPTER 1:  .. .  INTRODUCTION  x  i  x  v  x  v  1  1.1  L o c a t i o n and Access  1.2  Cl imate  1.3  Glaciation  k  1.4  H i s t o r y o f Development  k  1.5  P r e v i o u s G e o l o g i c a l Work  6  1.6  Purpose and Method  6  CHAPTER 2: 2.1  1 .  REGIONAL STRATIGRAPHY AND STRUCTURE Regional  Geology  k  9 9  2.1.1 2.1.2  A s i t k a Group T a k l a and H a z e l t o n Groups  9 12  2.1.3  Sustut  Group  16  2.2  Regional  Structures  16  2.3  Regional  Metamorphic Grade  17  2.k  Tectonic Evolution  CHAPTER 3:  PROPERTY  GEOLOGY  18 19  3.1  Introduction  19  3.2  C l a s t Types  21  3.2.1 3.2.2 3.2.3  Basalt Clasts A u g i t e Porphyry B a s a l t C l a s t s F e l d s p a r Porphyry A n d e s i t e C l a s t s  21 „.....22 2k  v  i  vi i Page 3.2.4 3.2.5 3.2.6 3.2.7 3.2.8 3.2.9 3-3  Rock Types 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 3.3.6 3.3.7 3.3.8 3.3.9 3.3.10  3.4  4.1  37  V o l c a n i c l a s t i c Conglomerate U n i t s Sandstone U n i t s . . . . Crystal Tuff Units Lahar U n i t s A r g i l l i t e s and A r g i l l a c e o u s Mudstone U n i t s Shale Unit Limestone Unit • B a s a l t i c Dyke U n i t Mylonite Unit Background Chemistry o f Some Rock Types  .  ..  D i s c u s s i o n o f the D e p o s i t i o n o f the V o l c a n i c l a s t i c Sequence 3.4.1 3.4.2 3.4.3  CHAPTER 4:  T r a c h y t i c - F e l d s p a r B a s a l t (or Bladed F e l d s p a r Porphyry Basalt) Clasts ..... 25 Gabbroic Basalt C l a s t s •. 28 Hornblende F e l d s p a r P o r p h y r i e s 28 C o m p o s i t i o n o f Moosevale F o r m a t i o n C l a s t s With Rocks o f U n d e r l y i n g Formations ........28 Geochemistry o f the V o l c a n i c C l a s t Types . . . . . . 30 Other C l a s t Types 36  Sedimentary S t r u c t u r e s Stratigraphy D e p o s i t i o n a l Environment  39 .47 49 49 51 52 52 54 56 56 ..58 58 60 62  METAMORPHIC PETROLOGY AND WHOLE ROCK TRACE ELEMENT CHEMISTRY...65 Introduction 4.1.1 4.1.2 4.1.3 4.1.4 4.1.5 4.1.6 4.1.7 4.1.8 4.1.9 4.1.10 4.1.11  Chlorite Carbonate Epidote Quartz Prehnite Sericite Pumpellyite Albite Hematite Sphene Pyrolusite  65  o  ...  ..65 66" 68 70 70 71 71 73 73 73 74  4.2  Metamorphic R e a c t i o n s  74  4.3  Metamorphic Mineral. Assemblages  75  4.4  Temperatures o f Metarnorphism  77  4.5  Age o f Metamorphism  78  4.6  E l e m e n t a l Chemistry o f Metamorphic Zones  ..81  VI I I  Page CHAPTER 5:  ORE Ml NERALOGRAPHY AND FORM  5.1  Introduction  5.2  Ore Lenses  .  „  85 85 86  5.2.1 Outcrop Appearance o f Ore 87 5.2.2 Appearance o f Ore Lenses i n D r i l l Core 93 5.2.3 L i t h i c V a r i a b l e s and T h e i r R e l a t i o n to M i n e r a l i z a t i o n ..96 5.2.4 Optimum Ore H o r i z o n . . . . . 101 5.2.5 Chemistry o f the Ore Lenses 109 5.2.5 (a) Probabi 1 i t y P l o t o f Assay Data 109 5.2.5 (b) T r a c e Element C h e m i s t r y o f Ore Lenses ,109 5.2.5 (c) Major Oxide Chemistry o f Ore Lenses 114 5.2.6 Gangue M i n e r a l o g y o f Ore Lenses 114 5.3  S u l p h i d e - B e a r i n g Veins 5.3.1 5.3.2 5.3.3 5.3.4 5.3.5  122  General Outcrop Appearance and Gangue M i n e r a l o g y Ore Veins i n D r i l l Core . P o s t - O r e Movement i n Veins Trace Element Chemistry o f V e i n M a t e r i a l Age o f the V e i n M i n e r a 1 i z a t i o n  5.4 Opaque M i n e r a l o g r a p h y  129  5.4.1 M a g n e t i t e (and l l m e n i t e ) 5.4.2 Chalcocite 5.4.2(a) C h a l c o c i t e i n Ore Lenses 5.4.2(b) C h a l c o c i t e i n Veins 5.4.3 B o r n i t e 5.4.3(a) B o r n i t e i n Ore Lenses 5.4.3(b) B o r n i t e i n Veins , . 5.4.4 N a t i v e Copper 5.4.5 Chalcopy r i t e 5.4.6 Pyrite 5.4.7 Digenite 5.4.8 Covellite 5.4.9 M a l a c h i t e and A z u r i t e 5.4.10 C u p r i t e and L i m o n i t e 5.4.11 G r e e n o c k i t e 5.4.12 Hematite 5.4.13 C o n c l u s i o n s on Opaque M i n e r a l Assemblages 5.5  Analyses 5.5.1 5.5.2 5.5.3 5.5.4 5.5.5  o f Intergrowth  122 .126 127 127 127  and Replacement T e x t u r e s  Chalcoci te-Digeni te „.. Chal c o c i t e - B o r n i t e and Di geni t e - B o r n i t e C h a l c o p y r i t e - B o r n i t e (and D i g e n i t e ) C o v e l l i t e after Digenite D i g e n i t e and C o v e l l i t e a f t e r B o r n i t e  129 133 133 141 142 142 144 ...146 146 148 150 151 151 151 .....151 153 155 155 158 160. 160 167 167  5.6  R e l a t i o n s h i p o f Ore V e i n s and Lenses.  169  5.7  Zonation of M e t a l l i c Minerals  171  i n Ore Lenses  ix  Page CHAPTER 6 :  DISCUSSION OF DATA AND  6.1  Introduction  6.2  Previously 6.2.1 6.2.2 6.2.3  6.3  6.3.^ 6.3.5  of  Suggested O r i g i n s  Physical  G e n e t i c Model  Features'  Ultimate Origin of  6.5  Possible  O r e F l u i d Model  f o r Sustut  Hydrothermal  Prospecting  17^ 175  Copper  Fluids  Tools  „ „  Deposit  175 176 179 . 180 180 182  from 183 186 Changing 193 19 * 2  195  BIBLIOGRAPHY APPENDICES  ...  I n t r o d u c t i o n t o t h e Model P a r a g e n e t i c Sequence „ C a u s e s o f Ore Z o n a t i o n a n d S i m i 1 a r Z o n a t i o n s Other-Depos i ts Chemistry of P r e c i p i t a t i o n S i g n i f i c a n c e of Mineral Zoning in R e l a t i o n to Chemistry of S o l u t i o n  b.k  ....17^  .  Syngenetic Hypotheses Metamorphically Derived C h u r c h ' s Model  A Unifying 6.3-1 6.3.2 6.3.3  and Summary  P O S S I B L E GENETIC MODEL .  197 ....'„  202  X  LIST OF FIGURES '  Page  F i g u r e 1:  L o c a t i o n o f S u s t u t Copper.  .....2  F i g u r e 2:  The North C l i f f s  F i g u r e 3:  S t r a t i g r a p h i c column o f t h e S u s t u t Copper A r e a  10  F i g u r e 4:  R e g i o n a l geology o f a r e a around S u s t u t  11  F i g u r e 5:  B a s a l t c l a s t photomicrograph  23  F i g u r e 6:  A u g i t e porphyry b a s a l t p h o t o m i c r o g r a p h  23  F i g u r e 1:  F e l d s p a r porphyry a n d e s i t e photomicrograph  26  F i g u r e 8:  Trachytic feldspar basalt c l a s t in outcrop  ...26  F i g u r e 3:  T r a c h y t i c f e l d s p a r b a s a l t photomicrograph  ...27  3  Copper  F i g u r e 10:  Gabbroic b a s a l t photomicrograph  F i g u r e 11:  Hornblende porphyry p h o t o m i c r o g r a p h .  23  Figure  12:  Total a l k a l i  33  Figure  13(a):  Major o x i d e v s . s i 1 i ca va r i at ion diagrams  34  Figure 13(b):  T r a c e metal v s . s i 1 i ca v a r i a t i o n diagrams  35  vs. s i l i c a  „  diagram  F i g u r e 14:  Limestone c l a s t  Figure  15:  T y p i c a l v o l c a n i c l a s t i c conglomerate  Figure  16:  Bar graph showing  r e l a t i v e abundances o f rock t y p e s .  Figure  17:  Bar graph showing coarse f r a c t i o n  r e l a t i v e amounts o f m a t r i x t o „  F i g u r e 18:  F i g u r e 19:  i n v o l c a n i c l a s t i c rocks  Bar graph showing r e l a t i v e number o f o b s e r v a t i o n s o f sorting characteristics.  38 40 ..41  43 44  Bar graph showing r e l a t i v e number o f o b s e r v a t i o n s o f textural  classifications.  F i g u r e 20:  T y p i c a l t u f f a c e o u s sandstone  F i g u r e 21:  C r y s t a l t u f f photomicrograph  F i g u r e 22: , T y p i c a l F i g u r e 23:  27  45 interbed  laharic unit  Mud c r a c k s  i n a r g i l l a c e o u s mudstone  48 50 50 53  xi  Page F i g u r e 24:  Limestone r e e f i n d r i l l  h o l e 47  .  ....53  F i g u r e 25:  B a s a l t i c dyke o f North Zone  F i g u r e 26:  T y p i c a l r e p e t a t i v e l y graded bedding sequence.  F i g u r e 27:  Cross bedding i n t u f f a c e o u s sandstones  6l  F i g u r e 28:  Stratigraphic cross-section.  63  Figure 29:  Carbonate cement, t o l i t h i c v o l c a n i c g r a i n s  67  F i g u r e 30:  T y p i c a l metadomain form o f e p i d o t e  67  Figure 31:  Carbonate v e i n s w i t h e p i d o t e envelopes  69  F i g u r e 32:  P r e h n i t e v e i n swarm  69  F i g u r e 33:  P u m p e l l y i t e (green) pseudomorphic a f t e r h o r n b l e n d e  55 ........61  g r a i ns  72  F i g u r e 34:  S t a b i l i t y r e l a t i o n s o f the prehnite-pumpel1yite f a c i e s . 7 9  F i g u r e 35:  S t a b i l i t y fields of a 1bite-epidote-plagioclase-quartz..80  F i g u r e 36:  M a l a c h i t e s t a i n on shear zone.  90  F i g u r e 37'.  Ore lens  90  F i g u r e 38:  Outcrop v i ew o f i n t r a c l a s t p y r i t e  92  F i g u r e 39:  S u l p h i d e m i n e r a l i z a t i o n b r e c c i a t i n g host rock  92  F i g u r e 40:  P r o p o r t i o n s o f each l i t h o l o g i c type m i n e r a l i z e d w i t h chal coci t e P r o p o r t i o n s o f each l i t h o l o g i c type m i n e r a l i z e d w i t h pyrite.  F i g u r e 41: F i g u r e 42:  l o c a t i o n s on n o r t h e r n edge o f c i r q u e  P r o p o r t i o n s o f each p e r c e n t m a t r i x v a l u e m i n e r a l i z e d with chalcocite  97 98 99  F i g u r e 43:  Proportions o f d i f f e r e n t t e x t u r e groupings with chalcocite.  F i g u r e 44:  Proportions o f s o r t i n g values mineralized w i t h chal c o c i te  102  Grain s i z e c l a s s i f i c a t i o n chart with proportion o f each s i z e type m i n e r a l i z e d w i t h c h a l c o c i t e  103  F i g u r e 45: F i g u r e 46:  mineralized 100  Comparison o f d i f f e r e n t types o f s i g n i f i c a n t 1y c h a l c o c i t e m i n e r a l i z e d v a r i a b l e s w i t h each o t h e r i n rock t y p e s AGGR. .105  xii Page F i g u r e 47:  Optimum o r e h o r i z o n diagram  108  F i g u r e 48:  P r o b a b i l i t y graph o f copper assay v a l u e s .  110  F i g u r e 49:  C l o s e up o f o r e l e n s e s a t sample l o c a t i o n W104.  117  F i g u r e 50:  Photomi c r o g r a p h o f W104 o r e lens  117  F i g u r e 51:  P h o t o m i c r o g r a p h o f opaque m i n e r a l s and gangue.  118  F i g u r e 52:  P h o t o m i c r o g r a p h o f W32 o r e l e n s .  118  F i g u r e 53:  P y r i t e as rounded b l e b s i n c h l o r i t e  120  F i g u r e 54:  Sulphides  F i g u r e 55:  P h o t o m i c r o g r a p h o f network p y r i t e masses  121  F i g u r e 56:  E p i d o t e v e i n l e t s c u t t i n g c o u n t r y rock o v e r l y i n g W104 ore l e n s .  124  A b o r n i t e and c h a l c o p y r i t e pod i n a c a r b o n a t e - q u a r t z v e i n near W76  .124  F i g u r e 57:  ' s p e c k l i n g ' e p i d o t e masses i n sample 6B3.  ...120  F i g u r e 58:  Prehnite-quartz-epidote-carbonate vein, with chalcocite and b o r n i t e , c u t t i n g the North Zone dyke 130  F i g u r e 59:  D e t r i t a l m a g n e t i t e bed.  130  F i g u r e 60:  Scanning e l e c t r o n photomicrograph o f a m a g n e t i t e i n sample 88E2 w i t h e l e m e n t a l scans o f t h i s m a g n e t i t e and a n o t h e r from sample W33  132  F i g u r e 61:  S t r a i g h t - e d g e d c h a l c o c i t e g r a i n s as v o i d - f i l l i n g s i n f i n e f r a c t i o n of conglomerate.  135  F i g u r e 62:  B l e b s o f c h a l c o c i t e c o n c e n t r a t e d i n a q u a r t z - f i l l e d pore.135  F i g u r e 63:  Scanning e l e c t r o n photomicrograph, w i t h elemental scan, o f a c h a l c o c i t e g r a i n i n sample 13C3 137 S c a n n i n g e l e c t r o n photomicrograph o f c h a l c o c i t e b l e b s  F i g u r e 64:  and a . l a r g e r c h a l c o c i t e g r a i n  138  F i g u r e 65:  Thin, exsolved digenite laths in c h a l c o c i t e  140  F i g u r e 66:  Typical c h a l c o c i t e habit in a quartz-carbonate v e i n .  F i g u r e 67:  Myrmekitic intergrowth of c h a l c o c i t e in b o r n i t e  143  F i g u r e 68:  B o r n i t e w i t h e x s o l v e d c h a l c o p y r i t e l a t h s and supergene development o f d i g e n i t e .  143  ..140  xi i i Page F i g u r e 69:  Noncoherent e x s o l u t i o n o f c h a l c o c p y r i t e i n b o r n i t e I l b . . 1 4 5  F i g u r e 70:  N a t i v e copper g r a i n w i t h c u p r i t e r i m .  F i g u r e 71:  C h a l c o p y r i t e o c c u r r i n g as  F i g u r e 72:  C h a l c o p y r i t e i n q u a r t z amygdule  F i g u r e 73:  Scanning e l e c t r o n photomicrograph  . ..  147  intra-phenocryst material.  ..149 ....149  and e l e m e n t a l scan o f  a greenockite grain  152  F i g u r e 74:  P h o t o m i c r o g r a p h o f wispy c h a i n s and t r a i l s o f h e m a t i t e I 1154  F i g u r e 75:  Ion d i s p e r s i o n p l a t e s o f copper and i r o n w i t h i n a c h a l c o c i t e - h e m a t i te i n t e r g r o w t h a r e a  156  F i g u r e 76:  Phase diagram f o r the Cu-S s y s t e m .  159  F i g u r e 77:  S t a b l e phases on the j o i n Cu^FeS^-Cu2S  161  F i g u r e 78:  S t a b l e phases on the j o i n Cu^FeS^-Cu^ ^S^  161  F i g u r e 79:  S t a b l e phases on the j o i n Cu^FeS^-CuFeS2_  F i g u r e 80:  Isothermal  sections  400*C.  162  x  i n the Cu-Fe-S system at 200, 300 and 164  i  F i g u r e 81 :  Phase r e l a t i o n s i n the Cu-Fe-S-0 system at 3 0 0 ' C .  F i g u r e 82:  C o n c e p t u a l model f o r g e n e s i s o f S u s t u t  F i g u r e 83:  S i m p l i f i e d p a r a g e n e t i c m i n e r a l sequence f e n c e diagram f o r S u s t u t Copper ores 184 Log f ^ vs_. pH diagram o f the dominant aqueous s u l p h u r s p e c i e i a t 3 0 0 ' C and 1 bar p r e s s u r e 187 Log f r j o " ^S2 ^ ' 9 ^ Ou-Fe-Cd system a t 300*C  F i g u r e 84: •Figure 85:  a  r a f n  o r  t  n  Copper d e p o s i t .  .181  e  and 1 Bar p r e s s u r e Cu ' G e o l o g '  ... . . . 1 6 8  192  F i g u r e 86:  Sustut  D r i l l c o r e Coding Format  F i g u r e 87:  I nequi g r a n u l a r t e x t u r e c h a r t .  F i g u r e 88:  Sorting chart  204 t  207 207  xiv  LIST OF TABLES Page TABLE I:  Major Oxide A n a l y s e s  TABLE II:  f o r Dominant C l a s t T y p e s .  T r a c e Element Analyses f o r V o l c a n i c C l a s t s  TABLE III:  T r a c e Element Analyses  TABLE IV:  Major Oxide Analyses on Sample 8 8 N 4  TABLE V:  T r a c e Element Analyses  TABLE VI:  Major Oxide Analyses  TABLE VII: TABLE V I I I : TABLE  IX:  f o r Deep Samples  3T 32 57 59  f o r Metamorphic Samples  82  f o r Metamorphic Samples.  83  T r a c e Element A n a l y s e s  f o r Ore Lens S e t s  112  Major Oxide Analyses  f o r Ore Lens Set  115  T r a c e Element Analyses  f o r V e i n Samples  128  XV  LIST OF APPENDICES Page APPENDIX  "APPENDIX  I:  " G e o l o g " D r i l l Core C o d i n g Format f o r S u s t u t Copper  II:  Fossil  APPENDIX  I'll:  APPENDIX  IV:  Identification  '..  Cross-Sections  'r>\<xf>5  ivJ  213  217  Map 1 and C r o s s - s e c t i o n s £~  202  pe-c  teUL £#//£CJ/Y&^  CecK^v ^ " ^  &"  ;  $  f  219 -i  xvi ACKNOWLEDGEMENTS These a r e many. helpful  F a l c o n b r i d g e N i c k e l Mines L t d . has been v e r y  i n t h i s p r o j e c t from i t s  i n c e p t i o n . ' The company g r a n t e d easy a c c e s s  to the p r o p e r t y and p r i v a t e company f i l e s .  A l s o generous f i n a n c i a l s u p p o r t  was g r a n t e d t o t h i s a u t h o r by F a l c o n b r i d g e . s h o u l d r e c e i v e s p e c i a l thanks  include:  Employees o f t h i s company who  Mr. S.N.  Charteris for f i r s t  suggesting  the p r o j e c t , Mr. J . J . M c D o u g a l l , f o r s e t t i n g up the p r o j e c t , p r o v i d i n g f i n a n c i a l s u p p o r t , and v e r y h e l p f u l d i s c u s s i o n , Mr. D.H. Brown f o r l o o k i n g a f t e r Mr. J . H u g i , and h i s son John J r . , f o r s e t t i n g up the c a m p s i t e , and Mr. B. Downing, Mr. J . W i l s o n , and Dr. Special my s u p e r v i s o r ,  I.  Elliot  for f r u i t f u l  discussion.  of  ('Geolog')  was h e l p f u l  drill  the c o m p u t e r -  c o r e c o d i n g format and g e n e r a l d i s c u s s i o n .  in d i s c u s s i n g  time as  ideas c o n t a i n e d h e r e i n was dependent upon him.  Dr. C l . Godwin i s g r a t e f u l l y acknowledged f o r h e l p in d e s i g n i n g based  finally  thanks go to Dr. A . J . S i n c l a i r f o r generous use o f h i s the f r u i t i o n  finances,  Dr. T . H . Brown  the c h e m i s t r y o f o r e s o l u t i o n p r e c i p i t a t i o n .  Dr.  H.  Wynne-Edwards was very h e l p f u l as my s u p e r v i s o r d u r i n g the embryonic s t a g e s of t h i s p r o j e c t .  Dr. H . J . Greenwood i s thanked f o r h e l p f u l d i s c u s s i o n .  Mr.  N.  Stacey and Mr. G. Hodge are acknowledged f o r d o i n g e x c e l l e n t d r a u g h t i n g work. Mr. S t a c e y a l s o a b l y a s s i s t e d the a u t h o r i n l a b p r e p a r a t i o n o f samples and d i d atomic a b s o r p t i o n a n a l y s e s p o l i s h e d and t h i n s e c t i o n s . photography. tions.  Ms.  Dr.'s  R.V.  K. S c o t t  f o r copper.  Mr. B. C r a n s t o n prepared most o f  Mr. E. Montgomery a s s i s t e d  in l o g i s t i c s and  Best and H.W. T i p p e r a r e thanked f o r f o s s i l  i s thanked f o r i n s t r u c t i o n i n XRF t e c h n i q u e s .  identificaMs.  M c l n t y r e i s v e r y g r a t e f u l l y acknowledged f o r t y p i n g the l i o n ' s s h a r e o f final  draft.  discussion,  the  I. the  Thanks must a l s o go to my g r a d u a t e s t u d e n t c o l l e a g u e s f o r h e l p f u l these i n c l u d e :  R. Berman, R. Cook, R. L e t t , E . P e r k i n s ,  and G. N i x o n .  L a s t but by no means l e a s t , very s p e c i a l thanks go t o Ms. S.E. for ably a s s i s t i n g  Nickerson  i n f i e l d work and f o r p a t i e n c e and a s s i s t a n c e d u r i n g the  length of t h i s p r o j e c t .  1  CHAPTER 1:  1.1  INTRODUCTION  L o c a t i on and Access  Sustut Mountains,  Copper d e p o s i t  is  in the Swannel1  in n o r t h e r n B r i t i s h C o l u m b i a .  Range o f the  The d e p o s i t  i s a p p r o x i m a t e l y 370 km  n o r t h w e s t o f P r i n c e George and 193 km n o r t h e a s t o f Smithers centered at l a t i t u d e 56°37' the d e p o s i t  and l o n g i t u d e 126*^5*.  i s a p p r o x i m a t e l y 2k s q . km and l i e s 5-6  t a i n , on the s o u t h e a s t e r n s l o p e o f Mount The topography for Sustut  is  rugged.  the d e p o s i t  The c l a i m group  Elevations  ( f i g . . 2)  i s surrounded  Mounr  i n the a r e a range from 2^30 m R i v e r V a l l e y , g i v i n g a maximum  to t h e i r base.  i s 3^5 m from  In a d d i t i o n to the North  c o m p l e t e l y by c l i f f s w h i c h have a minimum  r e l i e f o f 225 m and w h i c h a r e s c a l e a b l e in o n l y two o r t h r e e chimneys. t r e e l i n e extends o n l y to 1575 m e l e v a t i o n , w e l l deposit. scree,  is  covering  km e a s t o f S u s t u t  On the p r o p e r t y , however, the maximum r e l i e f  the summit o f the N o r t h C l i f f s Cliffs,  ( f i g . 1) and  Savage.  Mountain t o 1050 m f o r the S u s t u t  r e l i e f o f 1380 m.  Cassiar-Omineca  below exposures  of  Area above the t r e e l i n e i s u n d e r l a i n by rock w i t h l o c a l  The  the moss c o v e r ,  t a l u s , and f e l s e n m e e r . Access  t o the d e p o s i t  is d i f f i c u l t .  The extreme r e l i e f  requires  the  use o f a h e l i c o p t e r , n o r m a l l y based a t Johansen Lake, which may be reached by f l o a t - p l a n e from P r i n c e George, o r by a poor g r a v e l v i a Germanson's extends  Landing.  A c o n t i n u a t i o n of t h i s  from Johansen Lake towards  road from F o r t S t .  John  r o a d , the Omineca Road,  Fal c o n b r i dge N i c k e l Mines  Ltd.'s Moose  V a l l e y base camp and a b r i d g e has been c o n s t r u c t e d over the Moose V a l e Creek, however, property.  this  road i s 9-6 km a t the c l o s e s t  to the n o r t h e r n edge o f  the  2  LOCATION MAP LEGEND \  TECTONIC \  THE \  CANADIAN  CORDILLERA  STUDY  V  \  BELTS  \  AREA  BORDERS  300 Km  \  200 mi  \V V \  ' ' V  \CASCADES X  F i g u r e I:  L o c a t i o n o f S u s t u t Copper,  north-central  BELT  British  Columbia.  OF  F i g u r e 2:  The North C l i f f s .  These c l i f f s  the n o r t h )  form the n o r t h e r n edge o f S u s t u t  (viewed from Copper  Deposit.  1.2  Climate  The c l i m a t e i s c o l d and damp w i t h e x t e n s i v e snow g e n e r a l l y u n t i l the end o f J u l y .  Weather d u r i n g the f i e l d season o f 1977 was e x c e p t i o n a l l y good  i n comparison w i t h p r e v i o u s  summers spent on the p r o p e r t y by personnel  F a l c o n b r i d g e N i c k e l Mines L t d .  The a u t h o r and h i s a s s i s t a n t  f i e l d camp on June 22 when t h e r e was an average drifts  a r r i v e d at the  snow c o v e r o f 1.5-1.8 m w i t h  up t o 6 m deep. I n t e r m i t t e n t snow f l u r r i e s and g e n e r a l o v e r c a s t  w i t h fog were e x p e r i e n c e d u n t i l  J u l y 23-  skies  A f t e r t h i s date m e l t i n g o f snow  began i n e a r n e s t and t h e r e were temperatures o f up t o 2 0 - 2 5 ' C . the camp were not t o t a l l y i c e - f r e e u n t i l  of  the b e g i n n i n g  Two t a r n s by  o f August.  Bad weather  c l o s e d i n a g a i n August 21 and snow f l u r r i e s recommenced n i n e days p r i o r t o d e p a r t u r e from t h e camp on Sept. especially  1.3  6.  The snow c o v e r was never t o t a l l y m e l t e d ,  i n t h e c e n t r a l p o r t i o n s o f the n o r t h e r n h a l f o f t h e p r o p e r t y .  G l a c i a t ion  Glacial  features  i n the general a r e a a r e t y p i c a l o f a l p i n e - t y p e g l a c i a -  t i o n and i n c l u d e c i r q u e s , hanging t a l u s and moraines  v a l l e y s , and t r u n c a t e d spurs a l o n g w i t h  i n the v a l l e y s .  The S u s t u t  R i v e r v a l l e y , w i t h i t s U-shape,  was c a r v e d by P l e i s t o c e n e g l a c i a t i o n and has hanging Savage, a t t h e d e p o s i t , and S u s t u t c a l l y t h e r e a r e two main p o r t i o n s ' N o r t h Z o n e , w h i c h extends 1  c i r q u e , and a s o u t h e r n from the c i r q u e .  1.4  i c e sheets  History of  from both Mount  into i t .  Physiographi-  t o the d e p o s i t , a n o r t h e r n bowl, the  from the North C l i f f s t o an e a s t e r l y  b o w l , t h e ' S o u t h Z o n e , which extends 1  trending  t o the s o u t h  i n t h e South Zone, was p r o -  t a r n s which a r e f e d by m e l t i n g snow.  There a r e a l s o  on t h e n o r t h e r n p a r t s o f Mount Savage.  Development  P l a c e r g o l d had been found 94D)  leading  F r e s h w a t e r f o r t h e camp s i t e ,  v i d e d by t h r e e s m a l l some s m a l l  Mountain  valleys  i n 1907-1908 ( L o r d ,  1948).  in the McConnell  Creek region(NTS  I n t e r e s t waned s h o r t l y  Mapsheet  t h e r e a f t e r , but  f o l l o w i n g the r e p o r t by C S . b r i e f l y spurred.  Lord ( 1 9 4 6 ) of p l a c e r g o l d ,  B o r n i t e and c h a 1 c o c i t e - r i c h f l o a t in the S u s t u t  v a l l e y d i r e c t l y below the S u s t u t prospectors.  stratigraphic sections  across  again  River  D e p o s i t were not r e p o r t e d by any o f the  In.. J 969 the Union O i l C o . ,  nearby peaks  i n t e r e s t was  in s e a r c h o f p e t r o l e u m , mapped  the n o r t h e r n p a r t o f Mount Savage and o t h e r  i n c l u d i n g S u s t u t Mountain and Dewar Peak.  d e p o s i t was not d i s c o v e r e d u n t i l  The S u s t u t  Copper  l a t e i n August 1 9 7 1 , when, the m a l a c h i t e  s t a i n e d c l i f f on the e a s t e r n edge o f the p r o p e r t y was o b s e r v e d by 0. Thomason d u r i n g h e l i c o p t e r r e c o n n a i s s a n c e  by F a l c o n b r i d g e N i c k e l Mines  Ltd.  T h i s d i s c o v e r y was f o l l o w e d by d e t a i l e d mapping and s a m p l i n g f o r the r e m a i n der o f the 1971 f i e l d s e a s o n , t i o n s o f copper s u l p h i d e s .  r e s u l t s o f w h i c h i n d i c a t e d economic c o n c e n t r a -  In 1972 a f i e l d camp o f t h r e e permanent  was c o n s t r u c t e d and diamond d r i l l i n g commenced. mapping c o n t i n u e d d u r i n g the f i e l d seasons o f e x p l o r a t i o n ceased u n t i l  1973 and 1974  holes  Claims nos.  a w h o l l y owned s u b s i d i a r y o f F a l c o n b r i d g e N i c k e l Mines  i n the a r e a and numerous  Wesfrob Mines BP M i n e r a l s  is  Ltd. of  Ltd.  i n 1 9 7 1 , i n t e r e s t was  in the immediate v i c i n i t y .  h o l d s W i l l o w , W i l l , A s i t k a , S i t , Saddle and V a l e c l a i m s ,  L t d . holds  the BAP, DS, B i r c h c l a i m s ; Nomad Mines  L t d . holds  the  the A c l a i m s , . ( s e e GEM 1974).  the 1977 f i e l d season the o n l y work  by BP M i n e r a l s  in the area was being  done  L t d . on the NIK c l a i m s near Johansen Lake, and by Cominco L t d .  which d i d some f i e l d work around Johansen Lake.  deposit,  c l a i m s were s t a k e d  A s i t k a and Bob c l a i m s ; Rio T i n t o holds During  At p r e s e n t the p r o p e r t y  1-132 w h i c h a r e h e l d by Wesfrob Mines  F o l l o w i n g the d i s c o v e r y o f the S u s t u t high  a f t e r which  ( s i z e AQ) were completed t o the end  o f 1974 w i t h a c u m u l a t i v e depth o f 1 6 , 9 2 5 - 1 m.  Vancouver,  The d r i l l i n g and p r o p e r t y  the w r i t e r ' s work d u r i n g the f i e l d season o f 1 9 7 7 .  One hundred and t h i r t y - n i n e d r i l l  covered by S u s t u t  buildings  Lake and some d r i l l i n g a t  Duncan  6 1.5  Previous  The f i r s t the McConnell  G e o l o g i c a l Work  geological  map o f the r e g i o n was a r e c o n n a i s s a n c e  Creek map area by C S .  d e s c r i b e d the b a s i c host  survey  of  Lord 1946-1948 (G.S.C. Mem. #251).  Lord  rock u n i t , the v o l c a n i c - t u f f a c e o u s - v o l c a n i e l a s t i c  T a k l a Group, and i t s s t r u c t u r e .  The Union O i l C o . ,  a number o f s t r a t i g r a p h i c s e c t i o n a c r o s s  (private report)  the area i n 1969, which has  compiled yielded  the most d e t a i l e d l i t h o l o g i c data on s u b u n i t s  o f the T a k l a Group t o . d a t e . :..  Church  u n i t s o f the T a k l a and  (1973, 1974)  the h o s t  rocks  r e d e f i n e d the fundamental  and t h e i r copper m i n e r a l i z a t i o n .  the northwest, developed a new s u b d i v i s i o n from t h a t o f C h u r c h .  p r e s e n t s t r a t i g r a p h i c nomenclature  Monger (1974), w o r k i n g  o f the T a k l a somewhat  These two s u b d i v i s i o n s  described to  different  have been combined to y i e l d the  (Monger S Church,  1977).  Burns (1973) s t u d i e d the metamorphic m i n e r a l assemblages o f what he termed the low grade  1  Takla-Haze1 t o n  regional  stratigraphy  1  Group i n the McConnell  metamorphic  isograds.  Ramage (1974) d e s c r i b e d both the  o f the area, i n c l u d i n g the S u s t u t  d e p o s i t , and the p e t r o g r a p h y  dominant c l a s t types w i t h i n the v o l c a n i c l a s t i c host d e f i n e d a metamorphic colour differences  isograd  in the host  rocks.  Harper  Pelly  (1974)  reasons  for  and c h e m i s t r y , and host  and an o r e g e n e s i s model  o f F a l c o n b r i d g e N i c k e l Mines L t d .  Copper d e p o s i t  emplacement.  i s t o d e s c r i b e the s u l p h i d e  rock 1 i t h o l o g y ,  mineralography  p e t r o l o g y , and c h e m i s t r y o f  in o r d e r to develop a h y p o t h e s i s  and e v a l u a t i o n o f o t h e r copper o c c u r e n c e s  implications i n the a r e a .  the  for ore genesis  The e v o l u t i o n o f a g e n e t i c model f o r the r e l a t i v e l y  Copper d e p o s i t might have i m p o r t a n t  of  presented a syn-  Purpose and Method  The purpose o f t h i s t h e s i s  Sustut  (1976, 1977)  mineralogy  based on f o u r seasons o r work by g e o l o g i s t s  Sustut  rocks.  f o r the d e p o s i t and proposed  t h e s i s of d e t a i l e d property geology,  1.6  Creek area and o u t l i n e d  and  large  in e x p l o r a t i o n  for  7 F i e l d work by the a u t h o r had two main a r e a s , rigorous  the most  important being  r e l o g g i n g o f c o r e u s i n g a s p e c i a l l y designed c o d i n g system m o d i f i e d  from B l a n c h e t and Godwin (1972).  Time l i m i t a t i o n s would p e r m i t l o g g i n g  of  o n l y about 3000 m o f c o r e which had t o be s e l e c t e d w i t h g r e a t c a r e , from the 16,925 m a v a i 1 a b l e , to p r o v i d e a 3~dimensiona1 image o f the d e p o s i t .  Details  o f the d r i l l  l o g form ( c o d i n g form) d e s i g n e d by the a u t h o r a r e g i v e n  in  Appendix  The system i s based on an e i g h t y column format i n w h i c h p a r a -  I.  meters such as copper assay v a l u e s ,  rock t y p e , amount and type o f  both  m e t a l l i c m i n e r a l i z a t i o n and a l t e r a t i o n m i n e r a l s , and number o f v e i n s o f a g i v e n a l t e r a t i o n m i n e r a l c o u l d be r e c o r d e d in a s t a n d a r d way. parameters were recorded a t i n t e r v a l s o f 1.52 logs). of  (Smaller  lithology).  m (equal  All  these  to 5 f t . to match a s s a y -  i n t e r v a l s were used f o r r e c o r d i n g a b r u p t r e c o g n i z a b l e changes This  systematic recording interval standardized a l l d r i l l  data and f a c i l i t a t e d c o r r e l a t i o n between h o l e s .  Nineteen d r i l l  holes w i t h a  c u m u l a t i v e l e n g t h o f about 3000 m were logged by t h i s method.  Parallel  g i n g o f the d r i l l  The  data  (drill  c o r e was a l s o r e c o r d e d in f i e l d note books.  l o g s ) were key punched f o r computer p r o c e s s i n g .  logged w e r e ; 2, 6, 112,  116, and  log-  resulting  The d r i l l  10, 13, 17, 25, 39, 44, 52, 53, 54, 77, 88, 96,  105,  holes 110,  132.  In a d d i t i o n t o c o r e l o g g i n g , mapping o f the p r o p e r t y .  f i e l d work a l s o e n t a i l e d s u r f a c e  (Sample numbers o f specimens  were p r e f i x e d w i t h a W, w h i l e those from the d r i l l drill  hole  h o l e number).  geological  c o l l e c t e d from o u t c r o p  c o r e were p r e f i x e d by the  The base map used was a 1 i n . = 200 f t . s c a l e g e o l o g i c a l  map o f the d e p o s i t produced by g e o l o g i s t s  o f F a l c o n b r i d g e N i c k e l Mines L t d .  P e t r o g r a p h y and metamorphic m i n e r a l assemblages were s t u d i e d s e c t i o n s o f a l l rock and c l a s t types and some o r e h o r i z o n s . ography was d e s c r i b e d from 98 p o l i s h e d s e c t i o n s , e l e c t r o n m i c r o s c o p e work was done on 6 s e c t i o n s t i o n o f some opaque and/or gangue m i n e r a l s .  in 58 t h i n  Ore m i n e r a l -  and f o l l o w up  scanning  to determine e l e m e n t a l composi-  8 Analyses using  X-ray  f o r Z n , C u , N i , R b , S r , and Na were c a r r i e d out on 47  fluorescence techniques.  der and then p e l l e t i z e d .  t i o n . methods . absorpt ion.  The samples were ground t o a f i n e pow-  F u r t h e r Cu a n a l y s e s  w h i c h showed >100ppm Cu c o n c e n t r a t i o n s  samples  were c a r r i e d out on 27  in the XRF runs,  using atomic  M a j o r . o x i d e c o n t e n t s were determined on 24 samples  samples absorp-  by a t o m i c  9  CHAPTER 2: REGIONAL STRATIGRAPHY AND STRUCTURE  2.1  Regional.- Geology  The general and the r e g i o n a l  s t r a t i g r a p h y o f the S u s t u t geology  area  i s shown in f i g u r e 4.  is o u t l i n e d in f i g u r e The host  Copper d e p o s i t has been c a l l e d the Sustut-Wi11ow Moosevale thesis  Formation by Monger and Church  a f i r s t - h a n d study o f the r e g i o n a l this  U n i t by Meyer  (1977).  the nomenclature o f Monger and Church w i l l  t i o n s o f u n i t s o t h e r than the Moosevale  investigation.  O l d e s t known rocks which  be a c c e p t e d .  General  literature  be e l a b o r a t e d on below.  i n the a r e a comprise the Lower Permian A s i t k a  Group,  by Late T r i a s s i c v o l c a n i c and v o l c a n i c l a s t i c  rocks o f the T a k l a Group.  sedimentary  u n i t , the e a r l y J u r a s s i c H a z e l t o n Group which grades  Asitka  T h i s group i s  i n t o the Bowser Lake Assemblage  in t u r n o v e r l a i n by a  in the extreme  stratigraphi-  southwest.  Group  Rocks o f the A s i t k a Group o c c u r on the n o r t h e a s t e r n f l a n k s o f Dewar Savage M o u n t a i n , and S u s t u t 2450 m. of  descrip  as t o the p o s i t i o n o f the  sedimentary  2.1.1  this  o f the area was beyond the scope o f  a problem t h a t w i l l  i s o v e r l a i n discomformably  c a l l y upwards  of  Formation are taken from the  geology  Sustut  (1974) and the  For the purposes  There has been some d i s c u s s i o n  T a k l a - H a z e l t o n Groups boundary,  u n i t t o the  3,  Peak.  Maximum t h i c k n e s s  of t h i s unit  As o r i g i n a l l y d e f i n e d by L o r d (1948), the u n i t c o n s i s t s  r h y o l i t i c l a v a s which a r e l o c a l l y s p h e r u l i t i c , and a n d e s i t e s  is  Peak,  about  o f a sequence commonly  dis-  t i n c t l y a m y g d a l o i d a l , w i t h a s s o c i a t e d t u f f s , and b r e c c i a s , c h e r t s , a r g i l l i t e s and l i m e s t o n e s .  The l i m e s t o n e s  generally consist of c r i n o i d a l  F o r a m i n i f e r a and c r i n o i d s from the 1 imestones at S u s t u t Fossils  debris.  near the top o f the A s i t k a  Peak were i d e n t i f i e d as b e i n g Lower Permian i n age,: Lord  from o t h e r l o c a t i o n s  in the McConnell  unit  (1948).  Creek Map a r e a , c o l l e c t e d by  UNIT I  UNIT 3 UNIT 2c UNIT 2b UNIT 2a  UNIT 1  OL  z  § LU  N  5  GROUP  UNIT 2  GROUP  SUSTUT -WILLOW UNIT  UNIT 4  TAKLA  GROUP  UNIT 3  TAKLA  TAKLA  GROUP  GROUP  TAKLA-HAZELTON  DIVISION  HAZELTON  TAKLA GROUP  LOWER  TRIASSIC  cf MONGEU (I9TS)  DIVISION  UPPER  UPPER  LOWER  GROUP  MIDDLE  . TAKLA  MESOZOIC  JURASSIC  UPPER  HAZELTON GP  BOWSER LK.GEJ  Fm. NAME Fm. NAME BURiMS *73 CHURCH MONGER MONGER 8 HARPER PERIOD ERA OR EPOCH LORD 1946 TIPPER 1959 M E Y E R ' 7 4 I 9 7 3 J 9 7 4 1974,1976 CHURCH'77 1977 RAMAGE74  TELKWA Fm. 4c 4a MOOSE" V A L E MIDDLE Fm. (3a-d) LOWER FORMATION  F i g u r e 3'- S t r a t i g r a p h i c column o f t h e S u s t u t Copper A r e a . T h i s diagram shows t h e c h r o n o l o g i c a l development o f a s t r a t i g r a p h i c n o m e n c l a t u r e . The upper member o f the Moosevale Formation (shaded) i s the h o s t t o S u s t u t Copper D e p o s i t .  iWW! ' ]'! !'' 1  1  1  LEGEND JURASSIC  i 1,1,1,1 i 1,1,1,1, i i 1,1 i, iilililiii!  m UPPER TRIASSIC  HAZELTON  .GROUP  MOOSEVALE  SAVAGE  Fm.  MTN  Fm.  ( T A K L A GP), DEWAR  PERMIAN  Fm.  ASITKA  GROUP  INTRUSIONS  GEOLOGICAL BOUNDARY FAULT  OUTCROP  WATERCOURSE META.  ISOGRAD  F i g u r e k: R e g i o n a l g e o l o g y o f a r e a around S u s t u t Copper ( a f t e r Monger and Church ( 1 9 7 7 ) and H a r p e r ( 1 9 7 7 J ) . ' S u s t u t Copper p r o p e r t y i s the a r e a o u t l i n e d on Savage Mountain,.. The r e g i o n a l metamorphic i s o g r a d i s a f t e r Burns ( 1 9 7 3 ) . ' ;  12 Lord show t h i s u n i t to range from p o s s i b l e Pennsy1 v a n i a n t o Lower P e r m i a n . The group as a whole; has an average d i p o f 50* s o u t h w e s t e r l y and i s o v e r l a i n discomformably by the T a k l a Group r o c k s .  However, Monger (1974) w o r k i n g near  Dewar Peak found t h a t the c o n t a c t was a f a u l t o r a t l e a s t " a sheared  strati-  graphic contact".  2.1.2 T a k l a and H a z e l t o n Groups Armstrong for  (1946 £ 1949) f i r s t  i n t r o d u c e d t h e f o r m a t i o n name T a k l a Group  Upper T r i a s s i c t o Upper J u r a s s i c b a s a l t i c and a n d e s i t i c v o l c a n i c and  a s s o c i a t e d s e d i m e n t a r y rocks He a l s o thought  i n the F o r t S t . James Map Area (NTS 93K & N ) .  the H a z e l t o n Group o f a n d e s i t e s , b a s a l t s and r e l a t e d b r e c c i a s  were J u r r a s i c t o p o s s i b l y Cretaceous  in age.  There was no v i s i b l e c o n t a c t  between the two groups i n h i s area o f mapping. Lord ( 1 9 4 6 , 1 9 4 8 ) , w o r k i n g i n an area t o the n o r t h o f t h a t o f Armstrong ( 1 9 4 9 ) , d e f i n e d Upper T r i a s s i c t o m i d d l e Upper J u r a s s i c and v o l c a n i c l a s t i c rocks  (Oxfordian)  volcanic  i n t h e McConnell Creek Map Area as b e i n g T a k l a Group  e q u i v a l e n t s , and found no c o r r e l a t i v e rocks o f t h e H a z e l t o n Group i n t h e a r e a . T a k l a rocks were s u b d i v i d e d , i n t o two u n i t s , an Upper D i v i s i o n and a Lower D i v i s i o n , by L o r d . assemblage",  A c c o r d i n g t o L o r d , t h e T a k l a Group i s a " c o n f o r m a b l e  having a t o t a l  D i v i s i o n b e i n g 3000 m t h i c k .  t h i c k n e s s o f g r e a t e r than 9900 m, w i t h the Lower In the map a r e a , t h e Lower D i v i s i o n  rocks com-  p r i s e the b u l k o f Dewar and Niven peaks, Savage Mountain and S u s t u t whereas Upper D i v i s i o n margins o f t h e s e peaks.  Peak,  rocks a r e found o n l y a l o n g t h e extreme s o u t h , Host t o the S u s t u t Copper d e p o s i t a r e Lower  southwest Division  rocks. The base o f the Lower D i v i s i o n , a c c o r d i n g t o Lord ( 1 9 4 6 , 1 9 4 8 ) , i s composed o f i n t e r l a y e r e d b l a c k t u f f a c e o u s a r g i l l i t e s and g r e e n i s h t u f f s .  These  rocks a r e t h i n l y bedded and commonly show graded bedding from c o a r s e r t u f f s a t the  base t o f i n e r a r g i l l i t e s on t o p . The sequence  is conformable w i t h o v e r -  !3 l y i n g agglomerates  and p i l l o w l a v a s .  These agglomerates  s o r t e d c l a s t s o f b a s a l t i c to a n d e s i t i c c o m p o s i t i o n , tuffaceous  inch l o n g " ,  ( L o r d , p. 16).  both massive and p i l l o w e d a n d e s i t e s and b a s a l t s . phenocrysts  a r e seen  underlying lavas.  in these l a v a s .  T u f f s are abundant  c l a s e and h o r n b l e n d e g r a i n s  decrease  i n the sequence a l s o . i n amount upwards  The l a v a s  are  augite  contain clasts  in the s u c c e s s i o n w i t h a u g i t e , The a r g i l l i t e s a r e  R a r e l y t h i n l i m e s t o n e beds o c c u r .  plagiopresent The  lavas  For example, the rocks which c o n -  Copper d e p o s i t are d e v o i d o f l a v a s .  Though no d i a g n o s t i c  fossils  were found w i t h i n the Lower D i v i s i o n a s s e m b l a g e ,  Lord (1948) a s s i g n e d the  u n i t to the Upper T r i a s s i c because  than Lower Permian and  passed c o n f o r m a b l y  i t was younger  i n t o the J u r a s s i c Upper  The Upper D i v i s i o n  of  i n the s e c t i o n and d i s a p p e a r c o m p l e t e l y i n the  uppermost p o r t i o n s o f the Lower D i v i s i o n . t a i n Sustut  black  Most commonly stubby  O v e r l y i n g agglomerates  as common d e t r i t u s .  poorly  in a m a t i r x which i s •  i n n a t u r e and which c h a r a c t e r i s t i c a l l y c o n t a i n s , " s t u b b y  a u g i t e p h e n o c r y s t s up t o o n e - q u a r t e r  elsewhere  a r e made up o f  it  Division..  rocks are d o m i n a n t l y v o l c a n i c f r a g m e n t a l s a t the base  and s e d i m e n t a r y , w i t h some i n t e r b e d d e d v o l c a n i c , rocks towards the top o f the sequence.  The dominant  amounts o f f l o w r o c k s .  rock types a r e t u f f s and agglomerates w i t h minor The t u f f s c o n t a i n fragments o f p l a g i o c l a s e ,  o f . t r a c h y t i c f e l d s p a r l a t h s , and l e s s commonly o r t h o c l a s e and q u a r t z and are g e n e r a l l y o f a n d e s i t i c c o m p o s i t i o n . t u f f s a r e the dominant c l a s t types q u e n t l y form the m a t r i x .  rock  grains,,  Fragments o f f e l d s p a r p o r p h y r y  in the a g g l o m e r a t e s .  Feldspar grains  The l a v a s t y p i c a l l y c o n t a i n "numerous w h i t e o r  lath-shaped p l a g i o c l a s e phenocrysts,  1/16  c r y s t a l l i n e groundmass" ( L o r d , 1948 p. 2 1 ) .  clasts  to £ inch l o n g ,  frebuff,  in a r e d d i s h , m i c r o -  Greywackes, composed o f c h e r t and  v o l c a n i c rock f r a g m e n t s , conglomerates made up o f d o m i n a n t l y c h e r t y c l a s t s p o s s i b l e A s i t k a Group a f f i n i t y , and b l a c k s h a l e s sedimentary rocks. Lord's  and  and a r g i l l i t e s make up the  T h i n r a r e l i m e s t o n e beds are a l s o p r e s e n t .  Upper D i v i s i o n , based on f o s s i l e v i d e n c e ,  i s e a r l y Lower  The age o f Jurassic  of  14 (Lower L i a s )  through t o Upper J u r a s s i c  Group e q u i v a l e n t s Tipper Lord's  (Oxfordian).  Lord found no H a z e l t o n  i n the McConnell Creek a r e a .  (1959) i n a r e v i s i o n o f T a k l a and H a z e l t o n Groups, s u g g e s t e d t h a t  Upper D i v i s i o n o f the T a k l a Group, s h o u l d be p l a c e d w i t h i n the H a z e l t o n  Group, thus Triassic.  r e s t r i c t i n g the T a k l a i n t h e McConnell  Creek area t o t h e Upper  T i p p e r ' s p r i n c i p a l reason f o r t h i s new boundary between t h e two  groups was the d i f f e r e n c e in t e c t o n i c s t y l e s o f the r e s u l t i n g two d i v i s i o n s . The Lower J u r a s s i c marked the b e g i n n i n g o f a p e r i o d o f t e c t o n i c a c t i v i t y sediments were eroded and d e p o s i t e d i n a t r a n s g r e s s i o n which had become emergent sion  i n Upper T r i a s s i c t i m e s .  upon the v o l c a n i c a r e a s  This s t a r t of  i s shown by the presence o f sediments w i t h i n L o r d ' s Subsequent  to suggestions of Tipper  Hazelton terminologies  wherein  Upper  transgres-  Division.  (1959), f i e l d usage o f T a k l a and  i n the a r e a become somewhat c o n f u s e d .  Geologists of  F a l c o n b r i d g e N i c k e l Mines L t d . ( e g . Burns (1973), Ramage (1974)) h e l d w i t h the common usage a t t h i s p o i n t and r e f e r r e d t o the T r i a s s i c and J u r a s s i c c a n i c and v o l c a n i c l a s t i c s as t h e T a 1 k a - H a z e l t o n Group.  vol-  The host t o t h e S u s t u t  Copper d e p o s i t was i n f o r m a l l y r e f e r r e d to as the Sustut-Wi11ow U n i t  ( e g . Meyer,  1974).. Church  (1973, 1974), w o r k i n g near Savage M o u n t a i n , proposed a d i v i s i o n o f  t h e • s u c c e s s ion i n t o t h r e e main u n i t s .  The lowest u n i t , c o n s i s t i n g o f a n d e s i t e s ,  b a s a l t s , b r e c c i a s c o n s i s t i n g o f fragments o f the f o r e g o i n g corresponds lastic  to Lord's  r o c k s ; whereas,  limestone.  Lower D i v i s i o n .  l a v a s , and t u f f s ,  The m i d d l e u n i t c o n s i s t s  the upper u n i t c o n t a i n s  of volcanic-  t u f f , a r g i . l l i t e , c h e r t , and  Church proposed t h a t the T a k l a - H a z e l t o n boundary be p l a c e d e i t h e r  near the top o f t h e - m i d d l e u n i t where a p o l y m i c t i c conglomerate s u b a e r i a l e n v i r o n m e n t , o r a t the base o f the upper u n i t .  indicates a  A boundary a t the base  o f the upper u n i t r e f l e c t s the d i f f e r e n t c h e m i c a l c o m p o s i t i o n s o f t h e lower and middle u n i t s analyses,  r e l a t i v e t o the upper u n i t .  C h u r c h , on the b a s i s o f a r c f u s i o n  found t h a t the lower and m i d d l e u n i t s were b a s a l t i c , w i t h some  1  andesite, rhyoli  whereas  (Lord,  (1974, 1976)  Triassic  sic  (lower  members  and  of  Lord's The  of  the  and  This  second  volcanic  with  the  unit  is  correlative  Sustut  The-Lower  of  andesitic,  Formation The  the  is  lowest  and  the  Copper  the  with  some  middle  the  and  minor  called  the  Group  lavas  and  Formation base  of  deposit.  within  basaltic third  and  North  These  the  Upper  forms  of  which  are  of  that  breccias,  tuffs,  sedimentary be  correlative  Group.  Bowser  the  Formation  would  Hazelton  of  rocks,  them the  The  Lake  and  range  making  into  final  Assemblage  of  the  one of  from  host  formations.  portion  upper  age  the  of  agglomerates  consists in  up  three  northern  subunits  Formation  formations  subunits  rocks.  group  Cliffs,  into Lord's  interbedded  Jurassic  two  rocks  remainder  and  basal  in  Telkwa  age  the  Trias-  are  andesitic  of  in  subdivided  contains  The  and  volcanic  whole  the  the  unit  of  Late  breccias  the  and  2,  between  Upper  within  Takla  three  than  of  breccias,  into  Jurassic  to  region,  subdivided  divided  boundary  rather  identification  associated  unit  Division  Triassic  Peak  also  Formations  Middle  Upper upon  Group,  up o f  Upper  is  and  the  volcanic Upper  Savage tuffs,  host sand-  Triassic  Jurassic.  and  basis  (ibid.)the  of  conglomerates.  Monger  to  Takla  Middle at  Sustut  through  the  the  was  and  Dewar  and  Monger's  sedimentary  Copper,  the  Church's  Smithers  with  based  flow,  made  early  (1976, 1977)  Mountain.  stones  is  N i l k i t k w a and  Harper  is  the  Monger  Hazelton  conglomerate.  rocks  consists  the  unit  Lower  in  in  unit  with  Jurassic  the  was  found  second  part  and  three  dacitic  placed  basaltic  correlative  polymictic  as  The;  that  Division.  is  and  in  Upper  lowest  group.  to  was  This  fossils,  basal  Division.  basal  to  been  Jurassic.  Norion)  units.  Lower  and  unit  found  shouldhave  19^8)  the  the  upper  tes.  Monger  four  the  5  for  Takla  Church's a  (1977)  discussion  Group  format ions:Dewar  is  stratigraphic  of  defined  Formation,  the as  regional Upper  Savage  subdivisions  will  stratigraphy.  Triassic  Mountain  in  age  be  In and  Formation,  used  their consists  and  here  work of  Moosevale  16 Formation. sections  The Dewar a n d S a v a g e M o u n t a i n  a t the respective mountains,  Formation  i s made up o f a r g i l l i t e ,  The S a v a g e M o u n t a i n pillow  the Moosevale massive  Copper, w i l l  Sustut  the McConnell  conglomerates, and  tuffs.  spar,  Monger  (1977)  subdivided  i s made up o f  interbedded sandstones and  overlying  host  to Sustut  t h e T a k l a Group  is  Group.  Group  To t h e s o u t h w e s t , in  w i t h minor  Discomformably  the Telkwa Formation o f t h e H a z e l t o n  2.1.3  unit o f v o l c a n i c b r e c c i a , a middle  600 m t h i c k , member a c t u a l  below.  T h e Dewar  and b r e c c i a s .  t h e l o w e r , 900 m t h i c k , member  the upper,  be d i s c u s s e d  t o be p a r t l y c o e v a l .  vol c a n i c l a s t i c sandstones,  vol c a n i c l a s t i c conglomerates shales-,  named f o r t h e d e f i n i t i v e  volcanic breccia unit.  i n t o two m e m b e r s ,  fossi 1 iferous  a r e thought  Formation has a b a s a l  l a v a u n i t , and an upper  Formations,  outside  t h e map a r e a ,  C r e e k Map A r e a .  sandstones,  Pebbles  porphyries,  These  w i t h minor  rich  a r e t h e Upper C r e t a c e o u s  lenses  i n the conglomerates  and a u g i t e  Lord described the youngest  lavas.  group and h i s u n d e r l y i n g Upper J u r a s s i c ,  o f coal  and f o s s i l  areof granitic Lord thought  rocks,  Sustut wood  rocks Group  fragments,  cherts,  feld-  t h e c o n t a c t between  U p p e r D i v i s i o n was a n a n g u l a r  this  uncon-  formity. 2.2 R e g i o n a l  Structures  The most p r o m i n e n t regional This  extent,  fault,  also  northwesterly  structural  t h e most  features  s i g n i f i c a n t being  i n t h e map a r e a a r e f a u l t s o f t h e Omineca F a u l t  known a s t h e Two L a k e C r e e k  a l o n g Two L a k e C r e e k  lineament  t o t h e southwest  the absence o f v i s i b l e s t r a t i g r a p h i c markers, Omineca  Fault  t o have a v e r t i c a l  (1974) s u g g e s t s oldest  that this  and l a t e r  uplift  trends  1973),  Despite  (1977) b e l i e v e s t h e thousand  feet.  Church  p e r i o d o f time w i t h the  o f the T r i a s s i c  i t may have  19^8).  o f Savage M o u n t a i n .  f a u l t was a c t i v e o v e r a l o n g  along  (Church,  displacement of several  movement o c c u r i n g b e f o r e p o r t i o n s  erupted,  Harper  (Lord,  pillow basalts  provided the source  areas  were  f o r poly-  17 m i c t i c Takla  conglomerates.  There a r e o t h e r minor f a u l t s p r e s e n t w i t h the same t r e n d and a l s o a n o t h e r group which t r e n d g e n e r a l l y n o r t h e a s t e r l y .  These two f a u l t d i r e c t i o n s  a r e r e f l e c t e d i n s m a l l e r s c a l e f a u l t i n g and j o i n t i n g w i t h i n t h e p r o p e r t y . F a l c o n b r i d g e N i c k e l . Mines Sustut  L t d . geologists  suggest  (eg. Harper,  1977) t h a t the  R i v e r V a l l e y i t s e l f may be f a u l t c o n t r o l l e d .  Harper  (1977) r e c o g n i z e d t h r e e phases o f f o l d i n g i n the a r e a .  The f i r s t  phase produced " g e n t l e f o l d s w i t h a x i a l planes s t r i k i n g 110-130*" ( H a r p e r , 1977, p.  These a r e p o s s i b l y  102).  second phase  synchronous  w i t h the n o r t h w e s t e r l y f a u l t s .  i s " m i n o r w a r p i n g o r t i l t i n g ; maybe f a u l t a s s o c i a t e d "  p.102) w i t h a x i a l p l a n e s  t r e n d i n g 130-170".  i s not e v i d e n t but a g e n e r a l  broad w a r p i n g  On the p r o p e r t y  (ibid.,  i t s e l f , folding  i s i n d i c a t e d by the change  from the North C l i f f s o f 10' t o 25' near d r i l l  h o l e no. 132.  The  in dips  Church •( 1.973) e s t -  imates the a x i s . t o t h i s w a r p i n g as having a t r e n d o f 167* w i t h a plunge o f l 4 ' S E . 2.3 Regional  Metamorphic  Grade  Burns (1973) s t u d i e d r e g i o n a l a l t e r a t i o n i n the g e n e r a l deposit. Peaks,  T h i s study  i n c l u d e d e x a m i n a t i o n o f samples  Savage M o u n t a i n , and s e v e r a l o t h e r mountains  from- Dewar and S u s t u t to the south.  t h a t rocks o f , and s t r a t i g r a p h i c a l l y above, the Moosevale had. metamorphic m i n e r a l assemblages f a c i e s o f low grade metamorphism, assemblages  isograd  i s shown i n f i g u r e k.  Moosevale northern  found  c o n s i s t e n t w i t h the z e o l i t e ( l a u m o n t i t e ) whereas  the rocks below the Moosevale had  f o r the a r e a , i n c l u d i n g S u s t u t  From t h i s Copper.  Burns  This  On the southern edge o f Dewar Peak, a l l t h e  Formation i s i n t h e l a u m o n t i t e f a c i e s i n l i e r o f Moosevale  Burns  Formation g e n e r a l l y  o f the h i g h e r grade p r e h n i t e - p u m p e l 1 y i t e f a c i e s .  d e f i n e d a metamorphic i s o g r a d  a r e a o f the  Formation).  (no data were c o l l e c t e d on the  No data a r e a v a i l a b l e on the Moose-  vale  i n the western edge o f Savage Mountain but on the S u s t u t  this  i s o g r a d o c c u r s near the top o f the Moosevale, w e l l  Copper p r o p e r t y  above t h e d e p o s i t  18 proper.  Throughout  as h a v i n g  Sustut  Peak, the Moosevale  l a u m o n t i t e f a c i e s metamorphic g r a d e .  F o r m a t i o n i s c l a s s i f i e d by Burns Thus the p r o p e r t y has an  anomalous metamorphic grade when compared to o t h e r rocks a t the same r e g i o n a l stratigraphic level .  :  A p r e h n i t e - p u m p e l 1 y i t e grade f o r the d e p o s i t was c o n f i r m e d by Ramage (1974), and a l s o by t h i s  2.4  study.  Tectonic Evolution  The S u s t u t  Copper a r e a i s near the e a s t e r n edge o f the Intermontane  o f the Canadian C o r d i l l e r a ( S u t h e r l a n d Brown e t a l . , 1 9 7 1 ) which extends the c e n t r a l Yukon t o s o u t h - c e n t r a l B r i t i s h C o l u m b i a .  This b e l t  Belt from  represents  i s l a n d a r c v o l c a n i s m and a s s o c i a t e d sediments o f M e s o z o i c age w i t h some fringing  reefs  ( G a b r i e l s e , 1976  ).  The i s l a n d a r c a f f i n i t y o f t h e s e  i s seen in s t u d i e s o f c l a s t l i t h o l o g i e s w i t h i n the d e p o s i t sequence  (see b e l o w ) .  i s l a n d a r c v o l c a n i c s are one p o r t i o n o f the t o t a l  e v o l u t i o n o f the  cordillera.  From P r o t e r o z o i c t o mid-Devonian time a m i o g e o s y n c l i n a l  o f sediments  was  sequence  The A s i t k a  The T a k l a -  H a z e l t o n i s l a n d a r c v o l c a n i s m began w e l l a f t e r the f i n i s h o f A s i t k a  (Gabrielse, sition  basin  basins  d e v e l o p e d which e x h i b i t changes from near shore marine depo-  (eg. w i t h d e l t a s )  successor  Group  F o l l o w i n g the d e p o s i t i o n o f the H a z e l t o n G r o u p , s u c c e s s o r 1976)  Group,  in the a r e a , i s thought to have been d e p o s i t e d on o c e a n i c  ( i b i d . ) w h i l e the l i m e s t o n e s developed on v o l c a n i c p l a t f o r m s .  deposition.  sequence  l a i d down as " a c o n t i n e n t a l t e r r a c e t h a t d e v e l o p e d a l o n g the  w e s t e r n margin o f the North American c r a t o n " ( i b i d . . p . 493).  crust  This  i s marine and i s o v e r l a i n by d a c i t i c v o l c a n i c s which a r e s u b a e r i a l .  These  the basal  volcanics  t o nonmarine  (eg. l a c u s t r i n e s e d i m e n t s ) .  rocks c o m p r i s e the Bowser Lake Assemblage.  These  Thus the g e n e r a l  sequence s t a r t e d w i t h miogeosync1ina1 and/or o c e a n i c c r u s t s e d i m e n t a t i o n , l e d to i s l a n d a r c v o l c a n i s m o f T r i a s s i c to m i d - J u r a s s i c age w h i c h g r a d u a l l y subaerial  in n a t u r e and which was  successor  sediments.  became  in t u r n f o l l o w e d by near shore to nonmarine  19  - CHAPTER 3: PROPERTY GEOLOGY  3-1  I n t r o d u c t ion  P r o p e r t y geology than 600 m t h i c k  s t u d i e s a r e r e s t r i c t e d to e x a m i n a t i o n o f the g r e a t e r  upper member o f the Moosevale F o r m a t i o n .  the lower 420 m o f t h i s sequence holes  I n t e r p r e t a t i o n of  i s based on study o f the two deepest  drill  (88 and 110) -and a p o r t i o n o f o u t c r o p a t the base o f the North C l i f f s ,  most s u r f a c e exposures  are precipitous  cliffs.  as  The upper 180 m was examined  i n g r e a t e r d e t a i l , by o u t c r o p mapping and l o g g i n g o f o t h e r diamond d r i l l  holes  (DDH's), because major copper m i n e r a l o c c u r r e n c e s a r e r e s t r i c t e d to t h i s  level.  At the base o f t h i s member (the area from which samples SILT and AGGL were taken - see a t t a c h e d map in pocket)  is a b l a c k , f o s s i 1 i f e r o u s  grades up i n t o a r e d , f o s s i 1 i f e r o u s a r g i l l i t e . typical  s h a l e , which  Above the red u n i t a r e the  vol c a n i c l a s t i c sediments o f the M o o s e v a l e , but the c o n t a c t between the  two i s o b s c u r e d i n d e b r i s .  The c o n t a c t appears to be a s l i g h t a n g u l a r uncon-  f o r m i t y because the u n d e r l y i n g s h a l e s  t r e n d n o r t h e a s t e r l y and d i p  southeast-  e r l y whereas the o v e r l y i n g rocks have n o r t h w e s t e r l y s t r i k e s and s o u t h w e s t e r l y d i p s which are c o n s i s t a n t Fossils  throughout the e n t i r e 600 m o f vol c a n i c l a s t i c r o c k s .  have not been found i n f i n e - g r a v e l members w i t h i n the v o l c a n i c l a s t i c  u n i t , thus the lowermost a r g i l l i t e s and s h a l e s appear t o be d i s t i n c t i v e in their fossi1iferous  nature.  These f o s s i 1 i f e r o u s s h a l e s  comprise the top o f  the lower member o f the Moosevale Formation (Monger, 1977)-  The lower member  i s " p r e d o m i n a n t l y massive b r e c c i a w i t h i n t e r b e d d e d graded sandstone and f o s s i l i f e r o u s mudstone"  ( i b i d . , p.  15).  Naming o f l i t h o l o g i c types  in the vol c a n i c l a s t i c u n i t s  p r o f u s i o n o f p o s s i b l e names in the g e o l o g i c l i t e r a t u r e . c a l l e d b r e c c i a s , a g g l o m e r a t e s , vol c a n i c l a s t i c etc.  i s hampered by the  These rocks have been  conglomerates,  fanglomerates,  There i s no nomenclature problem w i t h some u n i t s such as the  lahars  20 crystal  tuffs.  fraction  The  of b a s a l t i c  size,  in a f i n e r  which  range  tion  dominant  clasts  c l a s t s , . ranging from  fraction  in size  r o c k t y p e s , h o w e v e r , a r e made up o f a  from  a r e made up  1 m  in diameter  o f f e l d s p a r , a u g i t e , and a f i n e mud  to a very  to coarse  small v o l c a n i c  coarse  mainly of s i x d i f f e r e n t  coarse  sand.  distinct  The  grains,  coarse  basaltic  to  compositions with s c a t t e r e d occurrences of other types of c l a s t s . are mainly ness,  conglomerates  roundness,  and  of fresh  feldspar  volcanic  derivation  It should a l s o  be  composition of coarse  a u g i t e as s a n d s i z e - c l a s t s  from  noted  relatively t h a t no  fiamme o r o t h e r e x a m p l e s o f w e l d i n g appears  the c l a s t i c  material  nearby  basin of c l a s t i c  cation  in  and  1 m thick.  have.been  of  the  having  fresh-  presence  source area o f the  b e e n moved somewhat f r o m  rocks  The  t h a t the u n i t  is of  volcanism.  that there are  in outcrop or thin  deposition, with clasts  reworked  and  and  are f a i r l y  These s a n d - s i z e d , e v e n - g r a i n e d somewhat of  in t r a n s i t .  textural  as;, f i n e m u d s t o n e , s i l t s t o n e s ,  green  and  a r e b o m b - s h a p e d , and  seen  t u f f a c e o u s sandstones  contains a variety  merates,  These  section.  no  Thus i t  i t s provenance to a  suffered  some m o d i f i -  transit.  Tuffs to  has  indicates  c l o s e to the  clasts  clasts,  frac-  andesitic  w i t h a much l e s s e r q u a n t i t y o f s a n d s t o n e s .  basaltic  and  sand-  lahars.  these  and  clasts.  The  out  the sequence.  out  t h e 600  can  have d i f f e r e n t  c o l o u r and  m thick  grain  unit  size  grain  size  ( c o a r s e vs.  drill  core  (see  fine)  below).  T h e s e two have  can  be  combinations differences  T h u s , t h e r e a r e no g r o s s pile.  the  either  of  sequence In t h e  green  in character  whereas  throughthrough-  d i a d o c h i e s o f c o l o u r ( r e d vs_. g r e e n )  l e d to the c l a s s i f i c a t i o n  used  case  in matrices  are c h a r a c t e r i s t i c  differences  such  conglo-  red or green  r e d and  but  Formation  volcaniclastic  throughout  up  in o r i g i n  rocks of v o l c a n i c o r i g i n  t o some e x t e n t a l t e r n a t e .  rocks a p a r t i c u l a r  layers,  In summary, t h e M o o s e v a l e  rock types  and  thin  are v o l c a n i c  tuffaceous sandstones,  red c o l o u r s predominate  the coarser u n i t s  units  types of c l a s t i c  In a l l o f  the f i n e r - g r a i n e d  a b u n d a n t as  and  in logging  21 . R a r e l y , o t h e r rock types are s e e n .  Foremost  in i m p o r t a n c e , are s m a l l  l i m e s t o n e r e e f s which p r o b a b l y f r i n g e d the v o l c a n i c c e n t r e s .  A single  basalt  dyke c u t s the N o r t h Zone and i s exposed on s u r f a c e f o r a d i s t a n c e o f about 540 m, w h i l e in the South Zone the dyke o u t c r o p s  irregularly.  has been i n t e n s e , r n y l o n i t e s are developed l o c a l l y . l e s s abundant  A d e s c r i p t i o n of  these  rock types f o l l o w s an account o f the l i t h o l o g y , p e t r o l o g y ,  c h e m i s t r y o f the v o l c a n i c and o t h e r fragments o f the Moosevale  3.2  Where f a u l t i n g  t h a t c o n s t i t u t e the g r e a t  and bulk  Formation.  C l a s t Types  More than 95 p e r c e n t o f coarse c l a s t s p r e s e n t , throughout Formation (and thus the S u s t u t are s u b d i v i d e d  deposit)  the  are of v o l c a n i c o r i g i n .  Moosevale These  clasts  i n t o s i x main t y p e s , some o f which are very d i s t i n c t i v e in  hand specimens, whereas o t h e r s are d i s t i n g u i s h a b l e o n l y  in t h i n s e c t i o n .  There a r e p e t r o g r a p h i c v a r i a t i o n s w i t h i n each t y p e , however a l l types seem to be r e l a t e d g e n e t i c a l l y , as shown by t h e i r s u r p r i s i n g l y the f a c t t h a t they are g r a d a t i o n a l mineralogy).  s i m i l a r c h e m i s t r y and  in petrographic features  ( t e x t u r e and  Thus, though t h e r e a r e d i f f e r e n c e s between the v o l c a n i c c l a s t  types they a r e o f t e n s u b t l e c o m p o s i t i o n a l o r t e x t u r a l v a r i a t i o n s . c l a s t types  in d e c r e a s i n g o r d e r of abundance a r e ; b a s a l t , a u g i t e  The  six  porphyry  b a s a l t , f e l d s p a r porphyry a n d e s i t e , t r a c h y t i c - f e 1 d s p a r b a s a l t , g a b b r o i c and h o r n b l e n d e f e l d s p a r 3.2.1  Basalt  and o n l y  i s by f a r the most common c o a r s e c l a s t found w i t h i n  F o r m a t i o n . These are p r e s e n t throughout  r a r e l y a r e they absent  conglomerates. massive,  porphyry.  Clasts  Fine-grained basalt the Moosevale  basalt,  in a s i n g l e 5 - f o o t  the 600 m t h i c k  sequence  i n t e r v a l of vol c a n i c l a s t i c  In hand specimen these c l a s t s a r e seen t o be f i n e - g r a i n e d  g r e y i s h v o l c a n i c rock.  long, augite phenocrysts  about  Small w h i t e f e l dspar. c r y s t a l s about 0.5 mm 1 mm long are v i s i b l e in some specimens.  22 Fresh c l a s t s g e n e r a l l y are g r e y i s h but r a r e l y a r e r e d d i s h .  Amygdules  are  r a r e l y seen and where p r e s e n t c o n s i s t o f e i t h e r c a r b o n a t e , c h l o r i t e ,  albite,  or q u a r t z . In t h i n s e c t i o n ' ( f i g . 5) these c l a s t s c o n t a i n about 30 p e r c e n t p l a g i o c l a s e and up t o 15 p e r c e n t a u g i t e p h e n o c r y s t s plagioclase  laths.  Small pseudomorphs  set  in a p i l o t a x i t i c m a t r i x o f  of c h l o r i t e a f t e r hornblende  c r y s t s a r e p r e s e n t here and can form up to 2 volume p e r c e n t . crysts  a r e absent  Anorthite  pheno-  Augite  pheno-  in p l a c e s but l o c a l l y a r e p r e s e n t as g l o m e r o p o r p h y r i t i c masses.  c o n t e n t o f the p l a g i o c l a s e p h e n o c r y s t s  Both p l a g i o c l a s e and a u g i t e p h e n o c r y s t s s e c t i o n s and c r o s s - s e c t i o n s .  ranges from A n  a r e p r e s e n t as e u h e d r a l  The dimensions  o f the p h e n o c r y s t s  0 Q  t o An  c  .  longitudinal average  about  0.3 by 0.3 mm f o r a u g i t e c r o s s - s e c t i o n s , whereas p l a g i o c l a s e c r o s s - s e c t i o n s  are  up to 1.2 by 1.2 mm i n s i z e and l o n g i t u d i n a l s e c t i o n s average  0.45 by 0.3 mm.  Some o f the p l a g i o c l a s e p h e n o c r y s t s  Augite  pheno-  Small a p a t i t e n e e d l e s a r e p r e s e n t  in the  crysts  a r e not zoned p e r c e p t i b l y .  show o s c i l l a t o r y z o n i n g .  ma t r i x . 3.2.2  A u g i t e Porphyry B a s a l t  Clasts  These d i s t i n c t i v e c l a s t s are the second most common v o l c a n i c c l a s t t y p e . They have been d e s c r i b e d by a l l workers  in the area  (from Lord (1948) t o  Monger (1977)). In hand specimen t h e r e i s v a r i a b i l i t y , but a l l have l a r g e , up t o 3 by 2.4 mm, e u h e d r a l a u g i t e c r y s t a l s v i s i b l e ( g e n e r a l l y the a u g i t e c r y s t s appear to average t i o n o f amygdules,  1 by 1 mm).  V a r i a t i o n s a r e shown in c o l o u r ,  and v i s i b i l i t y o f f e l d s p a r p h e n o c r y s t s .  f r e s h e s t c l a s t s a r e very dark r e d d i s h  Amygdules  in hand specimen.  have up t o 20 p e r c e n t amygdules  propor-  Generally the  (almost b l a c k ) but pronounced red o r  more r a r e l y dark green c l a s t s are s e e n . in some cases a r e n ' t o b v i o u s  pheno-  visible.  are g e n e r a l l y p r e s e n t ,  Some a u g i t e porphyry  Feldspar phenocrysts  but  clasts  up t o 0.5 mm in  l e n g t h a r e seen r a r e l y but m o s t l y a r e not v i s i b l e in hand specimen.  23  Figure  5:  Basalt clast  g1omeroporphyritic This  view  F i g u r e 6:  i s 1.1  photomicrograph  augite cm  Augite  phenocrysts.  Note  w i t h opaque  magnetites.  b a s a l t photomicrograph  (x-nicols).  across.  porphyry  Large a u g i t e phenocrysts, c r y s t a l l i n e matrix  phenocrysts  (x-nicols).  with  opaque m i n e r a l s  are  in a  crypto-  also containing smaller plagioclase  Augite  phenocryst at bottom of p l a t e  i s 6.4  mm  across.  2k . In t h i n s e c t i o n ( f i g . 6) .these c l a s t s c o n s i s t o f c l i n o p y r o x e n e and p l a g i o c l a s e p h e n o c r y s t s  set  smaller plagioclase laths.  The groundmass may be g l a s s y .  (augite)  in a p i l o t a x i t i c t o f e l t e d groundmass o f Opaque m i n e r a l s  a r e found i n t e r g r a n u l a r l y grown w i t h p l a g i o c l a s e c r y s t a l s o f the m a t r i x . P l a g i o c l a s e phenocrysts the An c o n t e n t s  range from n i l to 30 p e r c e n t in t h i n s e c t i o n s  range from A n ^ to A n ^ .  These p h e n o c r y s t s  show o s c i l l a t o r y z o n i n g w i t h some h a v i n g a l b i t i c phenocrysts crystals  c o n t a i n i n c l u s i o n s of c l i n o p y r o x e n e .  in d i f f e r e n t s e c t i o n s  some r a r e l y as l a r g e as 2.1  ranges  rims.  also  Larger  and  usually  plagioclase  The average s i z e o f  these  from 0.5 by .3 mm to 0.9 by 0.3 mm w i t h  by .75 mm.  Pyroxene p h e n o c r y s t s  range from 10  t o 30 p e r c e n t i n :the c l a s t s and a r e almost e x c l u s i v e l y a u g i t e , but in a c o u p l e o f s e c t i o n s one or two small p h e n o c r y s t s o f e n s t a t i t e were i d e n t i f i e d . e n s t a t i t e grains phenocrysts.  are i n v a r i a b l y intergrown or  The a u g i t e p h e n o c r y s t s  i n c l u d e d in much l a r g e r  have two main forms: as  grown opaque g r a i n s . clase  These g l o m e r o p o r p h y r i t i c masses c o n t a i n i n t e r -  In the l a r g e , zoned, s i n g l e a u g i t e p h e n o c r y s t s ,  plagio-  Amygdules  are present  in a l l cases  but in v a r y i n g amounts  F e l d s p a r Porphyry A n d e s i t e  from 5 to 20  present.  Clasts  T h i r d most common v o l c a n i c c l a s t type i s the f e l d s p a r p o r p h y r y In hand specimen these a r e d i s t i n g u i s h e d r e c t a n g u l a r phenocrysts  of f e l d s p a r  andesites.  r e a d i l y by the p r e s e n c e o f equant  in a massive groundmass.  n o r m a l l y have dimensions o f 2 t o 3 rom. A u g i t e p h e n o c r y s t s  in c o l o u r .  2.k  About 1 to 2 p e r c e n t h o r n b l e n d e c r y s t a l s , now  r e p l a c e d by c h l o r i t e ( l o c a l l y w i t h h e m a t i t e r i m s ) , a r e  a r e seen l o c a l l y .  The  average 1.2 by 0.9 mm in s i z e , but a r e as l a r g e as 3 by  percent of a given s e c t i o n .  3.2.3  subhedral  i n c l u s i o n s a r e found a l o n g c r y s t a l growth p l a n e s o f the a u g i t e s .  a u g i t e phenocrysts mm.-  augite  large, euhedral,  zoned t i t a n i f e r o u s c r y s t a l s o r as l a r g e g 1 o m e r o p o r p h y r i t i c masses o f to anhedral a u g i t e g r a i n s .  The  The  and/or  If f r e s h , these c l a s t s are very dark r e d d i s h  to  phenocrysts amygdules  (almost  black)  25 When viewed in t h i n s e c t i o n p l a g i o c l a s e phenocrysts augite phenocrysts. c l a s e phenocrysts  ( f i g . 7)  these c l a s t s c o n t a i n 50 p e r c e n t  o f A n ^ t o An^q c o m p o s i t i o n , and 2 t o 10 p e r c e n t  The o v e r a l l t e x t u r e i s stumpy e u h e d r a l in a c r y p t o c r y s t a l 1 i n e m a t r i x .  to equant  In f r e s h specimens  m a t r i x i s seen to be a g l a s s w i t h some p l a g i o c l a s e m i c r o l i t e s . c l a s e phenocrysts Some p h e n o c r y s t s crysts 1.65  average  a r e a c t u a l l y g l o m e r o p o r p h y r i t i c masses.  where p r e s e n t , account  n e e d l e s are commonly  The  plagiozoning.  The augiite  pheno-  but glomeroporphy r i t i c masses range up t o  mm. These a u g i t e masses have  Amygdules,  this  by 0.6 mm in s i z e , and show o s c i l l a t o r y  average 0.6 by 0.45mm i n s l z e  by 0.9  3.2.4  1.5  plagio-  intergrown magnetite  crystals.  f o r up to 5 p e r c e n t o f the c l a s t s .  Apatite  visible.  Trachytic-Feldspar Basalt  (or Bladed F e l d s p a r P o r p h y r y  B a s a l t ) C1asts  T r a c h y t i c - f e l d s p a r b a s a l t c l a s t s are the most d i s t i n c t i v e l o o k i n g specimen o f a l l c l a s t s clase crystals  seen  ( f i g . 8).  in a f i n e r groundmass.  4 to 5 cm and up to 2 cm in w i d t h . blades  in some c l a s t s .  b l a d e s , but a s t r o n g This  They c o n s i s t o f prominent b l a d e d These p l a g i o c l a s e b l a d e s a r e as  There are a l s o  rosettes of  c l a s t type e x h i b i t s the g r e a t e s t  textural variation  phenocrysts  plagioclase  l a t h s and b l a d e s  and equant m a g n e t i t e g r a i n s .  is p l a g i o c l a s e phenocrysts  plagioclase  in a l l o t r i o m o r p h i c a u g i t e s .  set  blades  ( f i g . 9),anhedral in  augite parts  In some c a s e s 50 p e r c e n t  i n an o p h i t i c m a t r i x o f  subhedral  At the o t h e r end o f the s c a l e 25 p e r -  are in a m a t r i x o f p i l o t a x i t i c p l a g i o c l a s e m i c r o l i t e s s e t  Also present  contain  in a p i l o t a x i t i c  c e n t p l a g i o c l a s e arid 10 p e r c e n t a u g i t e g l o m e r o p o r p h y r i t i c masses o f crysts  feldspar  in t h i n s e c t i o n .  The groundmass f e l d s p a r s  a r e :i n c l uded suboph i t i c a l 1 y i n some o f the a u g i t e . o f the c l a s t  set  long as  common.  At one end o f the t e x t u r a l spectrum, the c l a s t s w i t h the l a r g e s t 55 p e r c e n t p l a g i o c l a s e and 10 p e r c e n t a u g i t e p h e n o c r y s t s  plagio-  intergrown  The c l a s t s where f r e s h a r e b l a c k w i t h w h i t e  red c o l o u r a t i o n o f the groundmass i s v e r y  groundmass o f subhedral  in hand  in t h i s groundmass type are s m a l l a u g i t e g r a i n s  pheno-  in g l a s s .  intermixed with  F i g u r e 7: (x-nicols).  F e l d s p a r porphyry a n d e s i t e Euhedral  p l a g i o c l a s e phenocrysts  c r y s t a l l i n e groundmass.  Figure The  8:  photomicrograph  This section  is  1.1  Trachytic feldspar basalt clast  l a r g e w h i t e c r y s t a l s are  plagioclase.  in c r y p t o cm a c r o s s .  in o u t c r o p ,  27  Figure  9:  Trachytic  (x-nicols).  This  phenocrysts section  Figure  is  10:  figure  shows  cm  section  Gabbroic  is  1.1  large  photomicrograph lath-like  anhedral  augite.  plagioclase This  across.  basalt  Note h y p i d i o m o r p h i c - g r a n u l a r This  basalt  intergranu1 ar  with 1.1  feldspar  cm  photomicrograph  (x-nicols).  t e x t u r e and q u a r t z - f i l l e d  across.  pore.  28 plagioclase microlites. type.  Amygdules  a r e found  in a l l v a r i a t i o n s of t h i s  The l a r g e s t p l a g i o c l a s e c r y s t a l s a r e 2 by 1.5 cm. A n o r t h i t e  ranging  from  t o A n ^ and the o p h i t i c t o s u b o p h i t i c  t h a t t h i s type i s an a n d e s i t i c b a s a l t 3.2.5 G a b b r o i c B a s a l t This  textures  in texture.  a r e stubby  o f the rock as p h e n o c r y s t s  amounts o f q u a r t z with feldspar.  crystals  these  specimen  t e x t u r e ( f i g . 10).  t a b l e t s and c o n s t i t u t e as much as 60 p e r c e n t  w i t h 15 p e r c e n t a u g i t e p h e n o c r y s t s . some o f which a r e zoned.  P l a g i o c l a s e and a u g i t e p h e n o c r y s t s ,  There i s a gross p i l o t a x i t i c  The a u g i t e  There a r e very  i n t h e groundmass g e n e r a l l y m i c r o g r a p h i c a l l y  by 0.45 mm and 0.9 by 0.6 mm i n s i z e r e s p e c t i v e l y . the groundmass.  In hand  In t h i n s e c t i o n t h e c l a s t s  have an a l l o t r i o m o r p h i c - g r a n u l a r t o h y p i d i o m o r p h i c - g r a n u l a r  o c c u r s as e u h e d r a l  indicate  Clasts  these c l a s t s a r e f i n e - g r a i n e d granular  crystals  contents  in nature.  type i s the l e a s t common o f the v o l c a n i c c l a s t s .  Plagioclase  clast  rare  intergrown  when p r e s e n t , average  1.2  A p a t i t e needles a r e seen i n  t e x t u r e to the p l a g i o c l a s e  in  clasts.  3.2.6 Hornblende  Feldspar  Porphyries  These a r e a minor v a r i e t y o f t h e f e l d s p a r p o r p h y r i e s . t a i n up t o 10 p e r c e n t hornblende p h e n o c r y s t s mm -in c r o s s s e c t i o n .  P l a g i o c l a s e phenocrysts  up as much as 50 p e r c e n t o f the r o c k . stubby e u h e d r a l phenocrysts  c r y s t a l s averaging  These c l a s t s  con-  ( f i g . 11) up to 4 mm long and 2.5 o f c o m p o s i t i o n An^g t o A n ^ make  These p l a g i o c l a s e p h e n o c r y s t s  1.5 by 0.45 mm i n s i z e .  a r e p r e s e n t as a r e r a r e e n s t a t i t e . c r y s t a l s .  c  are large-  Five percent  The o v e r a l l  augite  texture  in h y a l o p i 1 i t i c . 3 . 2 . 7 . C o m p o s i t i o n o f Moosevale U n d e r l y i n g Formations  Formation C l a s t s  Both Monger (1977) and Church T a k l a and H a z e l t o n s e c t i o n Moosevale  Compared With Rocks o f  (1978, p e r s . comm.), who have s t u d i e d t h e  i n the a r e a , d e s c r i b e f l o w rocks u n d e r l y i n g the  F o r m a t i o n which have e q u i v a l e n t c o m p o s i t i o n s  t o a l l the c l a s t  types  29  Figure 1 1 : polarized)  Hornblende porphyry photomicrograph showing w e l l  two hornblende c r y s t a l s .  developed c r o s s - s e c t i o n s  (planeof  S e c t i o n i s 2 . 9 cm a c r o s s .  30  in the Moosevale clasts.  Church  F o r m a t i o n , except f o r the f e l d s p a r ( 1 9 7 8 , p e r s . comm.)  s i t e s was contemporaneous an e a r l y stage  from b a s a l t i c to d a c i t i c . beads  (Church,  Formations  b e l i e v e s that formation of these  w i t h Moosevale  in the p r o g r e s s i v e  porphyry•andesitic  change  Formation d e p o s i t i o n and  ande-  represents  in the modal c o m p o s i t i o n o f  volcanism  A study o f the r e f r a c t i v e i n d i c e s o f f u s e d  1973) showed t h a t v o l c a n i c s  in the Dewar-Savage  a r e b a s a l t i c i n c o m p o s i t i o n , the Moosevale  b a s a l t i c w i t h some a n d e s i t e c o m p o s i t i o n s  glass  Mountain  v o l c a n i c s are  dominantly  (eg_. the f e l d s p a r p o r p h y r i e s ) , whereas  t h e o v e r l y i n g H a z e l t o n rocks a r e m a i n l y a n d e s i t i c w i t h a s i g n i f i c a n t  dacitic  component. 3 . 2 . 8 Geochemistry o f the V o l c a n i c C l a s t Types Partial T a b l e 1.  major o x i d e a n a l y s e s  The a n a l y s e s  on the v a r i o u s  are p a r t i a l  because  v o l c a n i c c l a s t types a r e  i r o n c o n t e n t s were not  e x a c t l y due t o incomplete d i g e s t i o n o f m a g n e t i t e . ly also Sr,  low because the m a g n e t i t e  is t i t a n i f e r o u s .  Rb, were made on some o f the c l a s t Figure  12 i s a t o t a l  alkali  vs.  types  silica  ascertained  S i m i l a r l y , t i t a n i u m is Analyses  f o r Zn, Cu, N i ,  diagram w i t h Macdonald and  (1971)  the c l a s t and dyke samples  in the a l k a l i  subdivisions  All  and Baragar  T h i s a l k a l i n e n a t u r e o f the Moosevale  volcanics  Irvine also  (1977)-  S i l i c a c o n t e n t s o f the c l a s t s v a r y u n i f o r m l y from 45 to 5 3 p e r c e n t . the v o l c a n i c c l a s t s samples  of  b a s a l t f i e l d as d e f i n e d by  ( i b i d . ) , and i n the a l k a l i n e f i e l d as d e f i n e d by  has been demonstrated by Monger  Katsura's  of a l k a l i c f i e l d s .  Macdonald and K a t s u r a (ibid.) .  like-  (Table 2 ) .  ( 1 9 6 4 ) and I r v i n e and B a r a g a r ' s plot  in  range from d o m i n a n t l y b a s a l t i c to a n d e s i t i c .  Thus  The dyke  (W23 and W99) are more s i l i c a - p o o r than the v o l c a n i c s .  Figure  13 i s a s e r i e s o f major o x i d e vs_. s i l i c a ,  s i l i c a v a r i a t i o n diagrams;  and t r a c e metal  vs.  the v a r i a b i l i t y in the c h e m i s t r y o f . t h e c l a s t  and between c l a s t s o f one type i s a p p a r e n t .  This  types  i s p r o b a b l y due t o d i f f e r e n c e s  in a l t e r a t i o n o f the c l a s t s , as a l l c l a s t samples were at l e a s t s l i g h t l y  altered  TABLE I MAJOR OXIDE ANALYSES DYKE  BASALT  SAMPLES OXIDE  Si0  2  Ti 0  2  W23 13.00  Al 03 2  kZ  AUGITE PORPHYRY  SAMPLES •  W99  88F2  88A6  hi.IS  .25  16 .75  1.03  0.82  0 .61  1.07  16.33  16.90  19 .60  17.3*1  FOP. DOMINANT CLAST TYpES  FELDSPAR  BASALT SAMPLES  110H5  6A1  53 .00  18.75  1 .30  17 .  16  (j  PORPHYRY  TRACHYT1C FELDSPAR  ANDES 1TE SAMPLES  BASALT SAMPLES  HORNBLENDE  13C3  W97AP  1311  1 10C8  1 16A1  88A8  18 .00  16.13  50.50  51  51.25  18.50  0 .59  1.22  0.57  0.80  1  0.92  15.22  18 .96  .1*1.59  20.56  18.12  17.74  16.78  3-87  2.11  2.91  3.37  3.11  2  1 .00  .50  .03  PORPHYRY  SAMPLES  88D1 hS  .50  0  .76  18 .90  3.65  3  .68  3 .58  3.16  3 .21  3.09  3.  MnO  0.16  0 .1V  0,.21  0.11  0  .11  0.09  0  .13  0.18  0.11  0.16  0.17  0.19  0 .12  MgO  7.80  7..10  1,.75  3.95  3 .65  2.65  3 .75  8.55.  1.80  1.00  1.65  1.10  2..35  CaO  9.98  10,.10  5..65  5.80  6.85  7.35  6.85  6.68  1.70  3.85  1.10  5.75  6..15  Na 0  2.69  2. • 7't  1..15  3.98  5..60  5.91  1 .17  3-55  3.88  1.75  3.86  1.06  1..78  ko  o.ai  0..77  0..61  2.96  0..30  1 .01  2..17  1.09  2.2.8  3.77  2.88  1,.87  0.56  0 .,'18  1 .05 .  0.72  0..72  0.81  0..18  0.61  O.89  0.81  1.30  0.97  0..61  2.58  3.,1*t  2. ,81  2.36  2. .18  2.37  2..25  3.03  1.6  2.75  3.01  2.55  2. .06  0.015  0.007  0.008  0..01  0.001  0..02  0 . 18  0.001  0.006  0,09  88.7't  90.  89.5*1  91..09  88.25  9 0 . .56  89.77  91.11  Total  Fe  2  2  p o 2  5  L.0.1 . Cu Total  —  88.59  19  . 1.15  —  91.96  " " " " " " " T h e s e a n a l y s e s were made by Min-En L a b r a t o r i e s , North V a n c o u v e r , B . C . .  —  91-58  90.15  .60  90.12  TABLE  II  TRACE ELEMENT ANALYSES FOR VOLCANIC CLASTS (PP™  Rock Type  Jsample No.  Dyke  Basalt  11 11 Augite  FeldsparPorphyry Trachy F e l d s p a r Basalt Hornblende Porphyry  3 2 1 . 1 2 ( ± 1 . 0 4 )  1 1 . 6 2 ( ^ 0 . 0 2 )  0 . 0 0  7 6 6 . 8 0 ( * 0 . 5 0 )  7 . 7 9 ( ± 0 . 1 3 )  2.35(*0.87)  323.66(^0.08)  33.15(t0.33)  8 . 9 4 ( + 0 . 6 8 )  1 1 7 . 5 0 ( ± 0 . 1 4 )  18.61(±2.15)  8 . 6 7 ( ± 1 . 1 1 )  4 2 1 . 4 3 ( ± 0 . 9 2 )  1 4 . 2 1 ( ± 0 . 0 5 )  17^.91(±57.93)  0.98(+0.58)  4 6 7 . 2 9 ( ± 1 . 8 5 )  4 0 . 8 3 ( ± 0 . 1 8 )  « 3 . 7 0 ( ± 0 . 0 6 )  352.7K±0.29)  0 . 0 0  6 7 6 . 7 5 ( ± 1 . 9 4 )  8 0 . 9 6 ( ± 0 . 3 4 )  1 8 . 5 8 ( ± 0 . 2 2 )  4 0 3 . 5 3 ( ± 1 . 6 2 )  4 8 . 1 1 ( ± 0 . 3 1 )  (t37o77)  1 3 6 . 9 9 ( * 0 . 8 1 )  71 - 5 3 ( ± 1 - 6 3 J  8 8 A 6  1  )  8 3 . i 6 ( + 2 . 5 4 )  69.56(±U35)  102.09(±3.15)  1 1 0 H 5  6 A 1  8  2 8  .  0  5  (  ^  -  1  1 5 ( ± 0 o 8 3 )  o  8 2 . 2 3 ( ± 2  1 3 C 3  8  0  0 1 )  1 8 8 . 4 2 5 ( ± 0 . 9 4 )  W 9 7 A P  1 2 8 . 5 8 ( ± 4 . 0 3 )  1 3 1 1  88A8  86.5«(±0.77)  Rb  73.39(iUl4)  147.75  8 8 F 2  2  Sr_  Cu  73.00(+0„96)  W 9 9  Porphyry  11 11  Zn  ±precision)  1832.52(+169.53)  4 6 . 9 5 ( ± 2 . 0 2 )  68.59(±1.83)  1 . 0 5 ( ± 0 . 0 8 )  1 8 . 2 0 ( ± 0 . 0 5 )  •  8 8 D 1  ..  5  .  1  .  7  5  U  0  .  6  6  )  8 8 2 . 8 1  (±92.83)  0 . 0 0  3 1 1 . 7 2 ( ± 0 . 1 2 )  2 5 . 0 6 ( ± 0 . 0 1 )  LEGEND  A l k a l i ne-Alkali  Irvine &  BasaltS  Baragar - MacDonald & Katsura  •  Dyke  A  Basalt  •  Augite  a  Fe I d s p a r  A  Trachy - Feldspar  o  Hornblende  por. por. por.  por.  Irvine & Baragar  MacDonald  TholeiitiC Subalkaline  46  48  Si0 Fi gure  12:. Total  alkali  vs_. s i l i c a  BasaltS  & Katsura  -MacDonald  & Katsura  - Irvine & B a r a g a r  50 0  (%)  d i a g r a m f o r l i t h i c c l a s t s and dyke  rock.  <J0  H °/.Na 0 4  JFA  2  a-  a  7-  S3  o  o  5-  D A  '/.M5O  o o  >  A  A O  A  A,  3  H I.2H ° A 'Io  K 0 2  A A  3  •  A  o  D  •/.P O 2  •  °H  s  a  B 03  0.6H  V.TIOj  *  •  A  o-  1.0  0.8 °/o CaO  H  0.6-  A A A :  O °A •  4H  0.2  CD  */• MnO  0.1 40  E  45  ZO  A  n O  O  SO  IN  —1  I6H  F i g u r e 13a: dyke r o c k .  M a j o r o x i d e vs_. s i l i c a v a r i a t i o n diagrams (Legend i s the same as f o r F i g u r e 12).  6  A A  O  n  54 ' 40  o  45  for l i t h i c  %SI02  SO  c l a s t s and  54  35  90-1  • ©  Ni ( ppm)  jo-]  iso-\  A Zn (ppm)  •  I0H  50H  I8&2  8  4  2  a  I50H  Cu(ppm)  l0  H  A  A  A  5H  a 40  45  50 <7oSi0  F i g u r e 13b:  T r a c e metal v s . s i l i c a v a r i a t i o n diagrams  l i t h i c c l a s t s and dyke r o c k . Fi gure 12).  54  2  (Legend i s the same as f o r  for  36 and .some were m o d e r a t e l y t o h i g h l y a l t e r e d . samples which have a c o n s i s e n t the l i t h i c c l a s t s .  p r e p a r e d by Monger (1977) f o r Moosevale  are s i m i l a r  in r e s u l t t o  copper c o n t e n t s  ranged from a p p r o x i m a t e l y  andesites.  i n the Moosevale  16 ppm to 90 ppm.  volcani-  Most o f t h i s  copper a n a l y s e s  a g r e e , e x c e p t t h a t apparent background  18 t o 175 ppm.  Samples  writer's  copper may vary  from  W97AP and 88D1 a r e c l o s e t o s u l p h i d e m i n e r a l i z e d  thus t h e i r high copper c o n t e n t s  ( r e l a t i v e to t h i s a u t h o r ' s  y s e s ) a r e p r o b a b l y a r e s u l t o f c o n t a m i n a t i o n o f the c l a s t s i z a t i o n processes.  those  Formation c l a s t s , e x c e p t Monger's  in f a v o u r o f the f e l d s p a r p o r p h y r y  Monger a l s o found background clastics  i s s u p p o r t e d by the two dyke  c h e m i s t r y because they a r e not as a l t e r e d as  These v a r i a t i o n diagrams  sample c o l l e c t i o n was b i a s e d  This  The medium copper v a l u e s o f W99  zones,  and Monger's a n a l by o r e m i n e r a l -  and 13C3 might  indicate  some c o n t a m i n a t i o n , however copper c o n t e n t s o f up t o and s l i g h t l y above 100 ppm would be e x p e c t e d in n o r m a l l y d i s t r i b u t e d c o p p e r . tent  (This  h i g h background  i s f u r t h e r e x h i b i t e d by a p r o b a b i l i t y p l o t o f copper assay v a l u e s -  consee  below). 3.2.9  Other C l a s t  Types"  There a r e s e v e r a l o t h e r types o f c l a s t s seen i n v e r y minor amounts. grained sedimentary  in the v o l c a n i c  Most o f these appear t o be c l a s t s o f  clasts.  These " o t h e r "  in diameter.  fragments  They a l s o a r e not l a r g e  i n sandy l e n s e s .  in t h a t they i n d i c a t e t h e r e was  These c l a s t s a r e t y p i c a l l y rounded and  in s i z e and most commonly a r e seen 1 t o k mm  In t h i n s e c t i o n euhedral  developed l o c a l l y in t h e s e c l a s t s . g l a s s fragments,  roundness as the v o l c a n i c  sediments.  C h l o r i t e c l a s t s a r e seen r a r e l y .  grains  mudstone,  are r a r e l y l a r g e , g e n e r a l l y about 2 t o 3 cm  However they a r e s i g n i f i c a n t  reworking of p r e - e x i s t i n g  massive.  reworked f i n e r -  rocks o f the same sequence, and i n c l u d e t u f f ,  and s i l t s t o n e f r a g m e n t s , w h i c h have the same general  conglomerates  These g r a i n s  c r y s t a l s of augite probably  represent  are volcanic  however they show no f l a t t e n i n g thus p r e c l u d i n g ash f l o w type  37 origins. Limestone c l a s t s a r e very r a r e but a r e found s c a t t e r e d v e r y w i d e l y throughout  the e n t i r e v o l c a n i c l a s t i c sequence  ( f i g . 14) .  These c l a s t s are 5 to  10 cm in d i a m e t e r and in o u t c r o p a r e most e a s i l y seen as d e p r e s s i o n s p r e f e r e n t i a l w e a t h e r i n g on exposed s u r f a c e s . containing f o s s i l identification  One such c l a s t  formed by  (sample W1009)  d e b r i s was s u b m i t t e d to the G e o l o g i c a l Survey o f Canada f o r  (Appendix If  G.S.C. Report No. 4-BEBC-78).  were c o r a l f r a g m e n t s , g a s t r o p o d s , t e e t h , and conodonts  The f o s s i l s  f o r a m i n i f e r a (Ammod ? s c u s ) ,  present  f i s h d e b r i s and.  (E p Tgondolel 1 a (p r i m i t i a) Mosher and Neogondolel 1a) The  c a t e d age f o r t h i s c l a s t i s Late T r i a s s i c , L a t e K a r n i a n to e a r l y N o r i a n . clasts  i n d i c a t e p r o b a b l e reworking o f s m a l l  reefs b u i l t  upon v o l c a n i c  reef accumulation, apparently  support  the l o c a l  These  islands  and do not appear to i n d i c a t e a provenance from u n d e r l y i n g f o r m a t i o n s . small  (One  in p l a c e , i n t e r s e c t e d by DDH k~I, seems to  d e r i v a t i o n o f such c l a s t s ) .  A l s o p r e s e n t are very minor  o f massive q u a r t z , maybe i n d i c a t i n g d e b r i s from a d i s t a n t s o u r c e .  clasts  One o f two  c l a s t s o f a d i a b a s i c n a t u r e are a l s o seen i n d i c a t i n g a n o t h e r minor phase  in  the v o l c a n i c a c t i v i t y .  3.3 Rock Types In t h i s s e c t i o n the p h y s i c a l c h a r a c t e r i s t i c s o f each d i f f e r e n t rock type present  in the upper member o f the Moosevale  be d e s c r i b e d . merates.  logging tuffs,  Formation at Sustut  The predominate rock type p r e s e n t  Copper w i l l  i s the v o l c a n i c l a s t i c c o n g l o -  These conglomerates are a l s o the rock t y p e o f which the most  d e s c r i p t i o n of physical system.  in importance are t u f f a c e o u s s a n d s t o n e s ,  l a h a r s and a r g i l l a c e o u s mudstones.  the North C l i f f s ,  intense  v a r i a b l e s was a c c o m p l i s h e d w i t h the computer-based  Subsidiary  and a l i m e s t o n e r e e f i s  crystal  Shale o c c u r s o n l y a t the base o f in a s m a l l p o r t i o n o f DDH k~J.  Also  d e s c r i b e d a r e the a l k a l i c b a s a l t dyke which c u t s the N o r t h Zone, and m y l o n i t e s caused by f a u l t i n g .  indi-  38  F i g u r e 14: plate  Limestone c l a s t  in v o l c a n i c l a s t i c r o c k s .  i s o f sample W1009, which was f o s s i 1 i f e r o u s .  This Note the  e a s i e r w e a t h e r i n g n a t u r e o f the c l a s t r e l a t i v e to the host  rock.  39 V o l c a n i c l a s t i c Conglomerate  3-3-1  V o l c a n i c l a s t i c conglomerates Formation.  Their character varies  Units a r e the dominant  rock type o f the Moosevale  in t h a t p r o p o r t i o n o f c l a s t types  from p l a c e t o p l a c e , r e l a t i v e amounts red and green c l a s t s  differ  vary, matrix colour  i s e i t h e r red o r g r e e n , and t e x t u r a l c h a r a c t e r i s t i c s such as p e r c e n t m a t r i x , s o r t i n g of fragments, logging  the d r i l l  e t c . vary.  Figure  15 shows a t y p i c a l conglomerate.  core, certain diagnostic  f e a t u r e s o f these  were r e c o r d e d c o n s i s t e n t l y f o r core l e n g t h s o f  conglomerates  m (5 f t . ) .  1.52  In  The major  c h a r a c t e r i s t i c d e s c r i b e d f i r s t f o r each 5 - f o o t i n t e r v a l was the c o l o u r o f matrix  (or f i n e f r a c t i o n ) vs_. t h a t o f dominant and minor c l a s t s ;  red and g r e e n . by g e o l o g i s t s  the  i n terms o f  The a u t h o r adopted the f o u r - l e t t e r code p r e v i o u s l y  developed  o f F a l c o n b r i d g e N i c k e l Mines L t d . s p e c i f i c a l l y f o r c o r e  A c c o r d i n g to t h i s code, a conglomerate w i t h a green m a t r i x , d o m i n a n t l y  logging. green  c l a s t s , and minor red c l a s t s would be r e c o r d e d as AGGR, w h e r e i n the A i n d i c a t e s a v o l c a n i c l a s t i c conglomerate,  the f i r s t G s i g n i f i e s  the green c o l o u r o f  f i n e f r a c t i o n ( m a t r i x ) , the second G, the dominant c o l o u r o f c o a r s e and R the p r e s e n c e o f minor coarse fragments w i t h a red c o l o u r .  the  clasts,  According  to  t h i s code, ARRR i s at one end o f the s c a l e and i n d i c a t e s red m a t r i x w i t h o n l y red c l a s t s ; AGGG, at the o t h e r extreme, i n d i c a t e s a green m a t r i x w i t h o n l y green c l a s t s .  Eight  defined using t h i s  possible variations  in the s i n g l e  rock type " A " can be  scale.  F i g . 16 i s a h i s t o g r a m o f the t o t a l  number o f o b s e r v a t i o n s  o f each type  o f v o l c a n i c l a s t i c c o n g l o m e r a t e , and o t h e r rock types found on the p r o p e r t y , t h a t were r e c o r d e d in the 19 d r i l l observations  holes s t u d i e d .  made d u r i n g core l o g g i n g ,  being v o l c a n i c l a s t i c conglomerate. f o r kl p e r c e n t o f a l l samples The b i m o d a l i t y  Of the 2101  rock type  1986 o r 95 p e r c e n t a r e c l a s s i f i e d as  The dominant v a r i e t y  i s AGGR, which  accounts  examined.  in g r a i n s i z e o f these conglomerates  was coded f o r each  o b s e r v a t i o n o f l i t h o l o g i c type u s i n g a two-way c l a s s i f i c a t i o n t a b l e  developed  40  F i g u r e 15:  T y p i c a l v o l c a n i c l a s t i c conglomerate.  This  conglomerate c o n t a i n s a p o o r l y s o r t e d l a r g e f r a c t i o n o f clasts  i n a f i n e r f r a c t i o n o f c o a r s e sand s i z e  Interbedded w i t h t h i s conglomerate  2 m across.  fragments.  i s a small muddy  w h i c h drapes over some l a r g e r c l a s t s .  This  lithic  view i s  layer about  1000  rv>!  J22±23__  "?->  ^  -d- X a  "^x  o,  /-A T  $ $ ^ % \ % \«&\$  LITHOLOGY  '  F i g u r e 16: Bar graph showing r e l a t i v e abundances o f rock t y p e s . T h i s graph r e p r e s e n t s the t o t a l number o f o b s e r v a t i o n s o f each rock type r e c o r d e d i n 10,000 f t o f c o r e . Note the l o g a r i t h m i c s c a l e f o r number o f samples,  kl  by B l a n c h e t and Godwin (1972). Sustut  Copper  F i g . 45 shows a l l s i z e v a r i a t i o n s seen on  and a l s o c o n t a i n s  classifications.  t h e . r e l a t i v e proportions of  these  As can be seen the f i n e f r a c t i o n ( m a t r i x ) m a t e r i a l  ranges  from a c l a y (of<1/256 mm in d i a m e t e r ) , to a c o a r s e sand o f 1 mm d i a m e t e r , whereas  the c o a r s e - g r a i n e d f r a c t i o n ranges from c o a r s e sand (about 2 mm) to  a boulder size  (> 256 mm).  t o f i n e sandy, 1/256  The dominant f i n e f r a c t i o n s i z e , though,  is  t o £ mm, and the major c o a r s e f r a c t i o n s are s m a l l  silty pebbles  t o b o u l d e r s , k to 256 mm. The p e r c e n t m a t r i x (as opposed to p e r c e n t c o a r s e f r a c t i o n ) was r e c o r d e d a t each i n t e r v a l and the p r o p o r t i o n s a r e shown i n f i g . 17c e n t a g e o f m a t r i x (or f i n e f r a c t i o n ) p r e s e n t the dominant amounts b e i n g 50 t o 60 p e r c e n t . ( 1.52 m)  assigned: sorted.  The p e r -  ranges from 20 t o 90 p e r c e n t , w i t h Average s o r t i n g o f e v e r y  i n t e r v a l was coded u s i n g a s o r t i n g guide  and Godwin ( 1 9 7 2 ) .  also  (Appendix  A c c o r d i n g t o t h i s code, s o r t i n g v a l u e s  I)  5 foot -  from B l a n c h e t  from 1 t o 9 a r e  a v a l u e o f 1 i s e x t r e m e l y poor s o r t i n g whereas 9 i s e x t r e m e l y w e l l F i g . 18 shows t h a t the s o r t i n g c h a r a c t e r i s t i c s o f t h e s e  range from 2 to 7 and the s o r t i n g , on the whole,  is poor.  conglomerates  Textures of  these  rocks were determined w i t h the i n e q u i g r a n u l a r t e x t u r e c h a r t o f B l a n c h e t and Godwin (1972) reproduced i n f i g u r e  k$-  T h i s c h a r t i s used as a two-way  i f i c a t i o n scheme t o f i r s t group specimens on the n a t u r e o f the m a t r i x . the m a t r i x i s f i l l e d w i t h v i s i b l e cement as w e l l  the t e x t u r e i s " c l o s e d " .  A further division  p e r c e n t a g e o f the rock t h a t forms the l a r g e f r a c t i o n . shows the number o f o b s e r v a t i o n s  ( i e . a true fine  i s then based on the The h i s t o g r a m o f  o f each " t e x t u r a l " v a l u e .  i n a n t t e x t u r e , 71 p e r c e n t o f a l l 5~foot samples,  Where  as some d e t r i t u s , the t e x t u r e  i s d e f i n e d as " o p e n " , and where the m a t r i x i s o n l y d e t r i t u s fraction)  class-  fig.19  The v e r y predom-  is for a closed matrix with  25 t o 50 p e r c e n t l a r g e f r a c t i o n .  The second-most  includes  samples and i s f o r an open m a t r i x w i t h 25 t o  14 p e r c e n t o f a l l 5 - f o o t  50 p e r c e n t c o a r s e f r a c t i o n .  important t e x t u r a l v a r i e t y  F i g u r e 17: Bar graph showing r e l a t i v e amounts o f m a t r i x ( f i n e f r a c t i o n ) to c o a r s e f r a c t i o n i n v o l c a n i c 1 a s t i c c o n g l o m e r a t e s .  F i g u r e 18: Bar graph showing r e l a t i v e number o f o b s e r v a t i o n s o f s o r t i n g c h a r a c t e r i s t i c s i n vol c a n i c l a s t i c c o n g l o m e r a t e s .  45  Closed  Framework  Open  Framework  n=1356  iooo H  n=259  1i&  n = 144 Q.  E co  100 H  n=103 "2?  CO  SSI  0)  n=24  E n = 13  z  10H Sip  C5-  n= 2  T  10-25 25-50 50-75 Volume  i > 75  Percentage  n=1 i <10  T  10-25 25-50 50-75  Large  Fraction  F i g u r e 19: Bar graph showing r e l a t i v e number o f o b s e r v a t i o n s o f t e x t u r a l c l a s s i f i c a t i o n s o f vol c a n i c l a s t i c conglomerates.  46 In  s u r f a c e mapping, the vol c a n i c l a s t i c  c h a r a c t e r i s t i c s are e s s e n t i a l l y (though in red  identical  conglomerates  to what  i s seen  core data are p r o b a b l y more r e p r e s e n t a t i v e ) .  pocket)  i s based  colouration.  upon s u b d i v i s i o n o f the rocks  No attempt  was  However, c o n s i d e r a b l e e f f o r t was  made a t d e t a i l e d expended t r y i n g  s t r a t i g r a p h y to the Moosevale Formation  based  The  and  their  physical  in the core l o g g i n g geology map  i n t o a dominantly textural  (MAP  1 -  green  or  subdivisions.  to e s t a b l i s h an informal,  on  l i t h o l o g y of coarse  clasts,  but to no ava i 1 . The  fine fractions  ( m a t r i c e s ) c o n s i s t o f d e t r i t u s made up o f g r a i n s o f  f e l d s p a r s , a u g i t e , small magnetite,  chlorite,  l i t h i c clasts  r a r e q u a r t z and  (sand s i z e and  smaller),  very r a r e e n s t a t i t e .  hornblende,  Small  lithic  c l a s t s are g e n e r a l l y subrounded to rounded.  P l a g i o c l a s e , a u g i t e and  are most commonly s u b a n g u l a r  locally  these g r a i n s are euhedral weathering,  crystals.  The  a r e rounded.  Generally,  f e l d s p a r s , b e i n g more r e s i s t a n t  are g e n e r a l l y whole c r y s t a l s whereas the a u g i t e and  a r e most o f t e n broken The  to a n g u l a r , but  hornblende  to  hornblende  fragments.  amount o f cement  i s v a r i a b l e , but  in most cases some cement  (in  the t h i n s e c t i o n s s t u d i e d , amount o f cement ranged  The  cement types  i s present  from n i l to 70 p e r c e n t ) .  in d e c r e a s i n g o r d e r o f abundance a r e ; c a r b o n a t e ,  chlorite,  q u a r t z , e p i d o t e , p r e h n i t e , hematite, and  rare a l b i t e .  In a g i v e n t h i n  section  two o r three cement types are o r d i n a r i l y  present.  e p i d o t e appears  to be a  product o f r e c r y s t a l 1 i z a t i o n o f a very f i n e s i l t y a b l y c o n s i s t e d mainly o f p l a g i o c l a s e fragments. effect  upon f i n e muds.  Pore  spaces o r openings  common w i t h the above cement m i n e r a l s and ials. rices packed  In general  i t can be s a i d  or c l a y e y m a t r i x , that The  hematite  w i t h i n the m a t r i x  that the p e r m e a b i l i t y and from o r i g i n a l ,  arrangements to very open pores, now  prob-  i s an o x i d a t i o n  p u m p e l l y i t e as normal  ( f i n e f r a c t i o n s ) have g r e a t v a r i a t i o n s silty  The  itself  are  f i l l i n g mater-  p o r o s i t y o f the matimpermeable  f i l l e d with  cement.  close  hi Fisher  (1961, p. 1413) would  classify  these rocks as e p i c l a s t i c  b r e c c i a s and/or e p i c l a s t i c v o l c a n i c conglomerates which by weathering and e r o s i o n o f l i t h i f i e d o r s o l i d i f i e d (1969) a l s o c a l l e d  subrounded  which  t o rounded  f e a t u r e s and groundmasses.  i n a m a t r i x o f v a r i o u s sand and s i l t  has no pumice o r shard fragments.  usually  volcanic  rocks " d e r i v e d rock".  Parsons  these types o f sediments e p i c l a s t i c v o l c a n i c b r e c c i a s and  described t h e i r general s t r u c t u r a l are  Imply  volcanic  rather well  stratified  The fragments s i z e s , but.  " E p i c l a s t i c volcanic breccias are  and show f a i r o r moderate s o r t i n g .  interbedded w i t h b e t t e r s o r t e d sandstones and c o n g l o m e r a t e s . "  They a r e  (Parsons, 19&9,  p. 288). 3.3.2 Sandstone Sandstones  Units a r e the second most common rocks p r e s e n t oh the Sustut  d e p o s i t , a c c o u n t i n g f o r a p p r o x i m a t e l y 3 p e r c e n t o f a l l types ( f i g . hand specimen  these rocks have,  colour variations  from p a l e green  Copper  20).  In  (due t o  e p i d o t e ) t o dark red ( h e m a t i t e - b e a r i n g ) . They a r e a l l g e n e r a l l y massive but in  some cases i n d i v i d u a l  g r a i n s are r e a d i l y v i s i b l e .  l a y e r s and lenses vary from 2 t o 3 cm f o r small are  up to 6 m t h i c k .  w i t h the dominant r e s t r i c t e d areal entire property.  T h i c k n e s s o f sandstone  intervals,  t o l a r g e beds that  In o u t c r o p these sandstones a r e seen t o be i n t e r c a l a t e d  v o l c a n i c l a s t i c conglomerates and f o r the most p a r t have very extents.  No one sandstone  In t h e d r i l l  l a y e r can be t r a c e d throughout the  c o r e the sandstones a r e most commonly p r e s e n t  as upper p o r t i o n s o f graded bedding sequences w i t h the conglomerates as the base. In  g e n e r a l , these sandstones are p o o r l y s o r t e d ,  sediments.  G r a i n s i z e s vary from what P e t t i j o h n  (2 t o 4 mm) t o g r i t t y consistent dominant  sandstones  ( >0.5 mm).  i n s i z e and show extreme  (1975) c a l l s  feldspathic granule gravels  I n t e r n a l l y t h e g r a i n s a r e not  ranges o f up t o 0.06 t o 1.4 mm. The  g r a i n s a r e p l a g i o c l a s e f e l d s p a r s which  cent o f g r a i n s p r e s e n t .  immature,  A u g i t e and l i t h i c  clast  can account f o r 50 t o 90 perg r a i n s a r e next most  48  F i g u r e 20: This  Typical tuffaceous  sandstone  conglomerate.  sandstone  i n t e r b e d in conglomerate.  l a y e r i s p r e f e r e n t i a l l y weathered r e l a t i v e to the  49 abundant, w i t h hornblende being the f o u r t h . c h . l o r t t e , and l e s s  commonly  limonite.  Other r a r e r g r a i n s  These g r a i n s  are m a g n e t i t e ,  a r e cemented by combina-  t i o n s o f c a r b o n a t e , q u a r t z , c h l o r i t e , e p i d o t e , p r e h n i t e , h e m a t i t e , and a l b i t e . Rarely  red mud cement forms as much as 40 t o 75 p e r c e n t o f the r o c k .  Pore  h o l e s are q u i t e commonly p r e s e n t and a r e f i l l e d w i t h any o f the above The l i t h i c g r a i n s  a r e subrounded  hornblende g r a i n s  are angular,  t o rounded whereas  sandstone  and r a r e l i t h i c  sandstone,  f e l d s p a r porphyry  Crystal Tuff The c r y s t a l  r e f e r s to a d i s t i n c t i v e  which c o n t a i n s  large feldspar  grains  These c r y s t a l s  a r e in a f i n e r m a t r i x  The c r y s t a l s  a r e up t o 1.5 mm l o n g .  i n c o l o u r but green m a t r i c e s  P e t r o g r a p h i c a l l y these t u f f s c o n s i s t o f e u h e d r a l  c r y s t a l s with euhedral The m a t r i x , p r e s e n t  a u g i t e c r y s t a l s , and/or  lithic  stubby  fragments  are  plagioclase (fig.  21).  from 40 to 60 p e r c e n t , i s e i t h e r a f i n e (<0.00l6 mm),  g r a n u l a r mass o f f e l d s p a r g r a i n s  of c h l o r i t i z e d g l a s s ; or a combination of  rocks a r e not very common and thus f i e l d  However, a t t h e top o f the North C l i f f s be t r a c e d f o r about  crystals.  euhedral p l a g i o c l a s e c r y s t a l s are v i s i b l e , and  The m a t r i x i s most commonly medium r e d d i s h  These  rock i s a  clasts.  reminiscent of a r h y o d a c i t i c porphyry.  the two.  This  t u f f u n i t s have dominant and d i s t i n c t i v e m i n e r a l  commonly o u t l i n e a crude b e d d i n g .  3.3.4  16)  crystals.  Units  In hand s p e c i m e n , numerous,  seen.  (fig.  found o n l y from 770 t o 778.5 f t . l e v e l o f DDH 132.  greyish white coarse-grained  3.3-3  the f e l d s p a r , a u g i t e , . and  and r a r e 1y t h e i r form i s as euhedral  The "AREN" on the l i t h o l o g y h i s t o g r a m  cements.  (sample W44 s i t e )  120 m, b e f o r e d i s a p p e a r i n g  in  r e l a t i o n s are  obscure.  a 1 m t h i c k bed can  rubble.  Lahar Un i ts Lahars  a r e one o f the more s t r i k i n g  rock types  In o u t c r o p they a r e seen to c o n t a i n a wide s i z e ments suspended  in the Moosevale  range o f rounded c o a r s e  in a muddy o r s i l t y m a t r i x ( f i g . 2 2 ) .  1 m to 3 m in d i a m e t e r .  Formation. frag-  Some o f these c l a s t s  The mud m a t r i c e s are e i t h e r dark red o r dark green  are in  Figure This of  21:  Crystal  p l a t e shows  plagioclase  matrix.  Figure  This  22:  photomicrograph  the t y p i c a l w e l l  and a u g i t e section  Typical  muddy m a t r i c e s . extensively  tuff  The  is  crystallized  phenocrysts 1.1  cm  in a  form  granular  across.  laharic unit with laharic material  interbedded with  (x-nicols).  large  blocks  in t h i s  conglomerates.  plate  and is  51 colour.  G e n e r a l l y these very l a r g e c l a s t s are few and f a r between w i t h i n the  m a t r i x and in t h i s  res.pect d i f f e r  from the c o n v e n t i o n a l conglomerates w h i c h have  a more c o n s i s t e n t s i z e range o f f r a g m e n t s .  The l a t e r a l  e x t e n t o f these  lahars  i s not g r e a t and they a r e p r o b a b l y b e s t thought o f as b e i n g l o c a l i s e d slumping f e a t u r e s . sequence  A g i v e n l a h a r may l o c a l l y form the base f o r a graded bedding  in which the top p o r t i o n i s a mudstone.  rocks would be grouped  In the d r i l l  in w i t h the r e g u l a r conglomerates  core  but t h e i r presence  e x p r e s s e d by the very l a r g e s i z e o f some c o a r s e f r a c t i o n s o b s e r v e d . P O R . ' s " i n f i g . 16 a r e o b s e r v a t i o n s  of  lahar units  i n t e r v a l was o c c u p i e d by a s i n g l e c l a s t  suspended 3-3-5  to 1680  (j_e. the f e l d s p a r p o r p h y r y  ft levels.  is  The "F-SPAR  in which a complete 5 f t  Lahars a r e p a r t i c u l a r l y n o t i c e a b l e i n t e r m i t t e n t l y in DDH 88, 1460 and from the 1660  these  clasts).  from the 1340  Here c l a s t s o f up to 1.5  to  mm a r e  i n a f i n e dark red a r g i l l a c e o u s mudstone m a t r i x .  Argillites  and A r g i l l a c e o u s Mudstone  The d i f f e r e n c e between these two  is  Units  t h a t the mudstones  are t h i n and  show mudcrack s t r u c t u r e s , w h i l e the a r g i l l i t e s , sensu s t r i c t o , are t h i c k e r bedded.  A r g i l l i t e s are found o n l y  i n the lower s e c t i o n s o f the  F o r m a t i o n where they form the base o f the upper member. red i n c o l o u r and show m i c r o b e d d i n g f e a t u r e s o f t h i n , and b l a c k muddy l a y e r s .  This  These  Moosevale rocks a r e deep  1 to 2 mm t h i c k , sandy  rock type i s made up o f 25 p e r c e n t  feldspar,  5 p e r c e n t a u g i t e and h o r n b l e n d e , 5 p e r c e n t s h e l l and 10. p e r c e n t opaque ments  in a c r y t o c r y s t a l 1 i n e m a t r i x .  f e l d s p a r and 0.08 fragments  The g r a i n s i z e s a r e 0.16  to 0.04 mm f o r  to 0.04 mm f o r a u g i t e and hornblende g r a i n s .  The s h e l l  look l i k e pelecypods and a r e p r o b a b l y Hal obi a . l i k e those  underlying shale  frag-  i n the  ( s e c t i o n 3 - 3 - 6 ) , but a r e not a d e q u a t e l y p r e s e r v e d f o r  posi-  tive identification. The 1025  to 1205  f t i n t e r v a l i n DDH 110. i s composed o f  i n t e r - and r e p e t a -  t i v e - b e d d e d r e d , ' g r e e n , and r a r e l y b l a c k a r g i l l i t e s w i t h red and green aceous  sandstones.  Each a r g i l l i t e  layer is  less  than 1.5 m in  tuff-  thickness.  52 In hand specimen small visible.  (< 1 mm  i n diameter) white f e l d s p a r g r a i n s a r e commonly  In t h i n s e c t i o n these a r g i l l i t e s e x h i b i t w e l l  o f t e n c o n t a i n small  s c a l e (a few c e n t i m e t e r s  wide) graded beds.  c o n s i s t o f f e l d s p a r g r a i n s , 0.06 mm t o 0.9 by 0.6 mm g r a i n s 0.75 mm  i n diameter,  cent o f the rock.  d e f i n e d bedding and These  i n diameter,  rocks  and opaque  s e t i n an i r r e s o l v a b l e m a t r i x which makes up 60 per-  No"argi11ites  are seen.in  the lower p o r t i o n s o f DDH 88, but  the a r g i l l a c e o u s matrix t o the l a h a r s a t the 13^0-1460 and 1660-1680 f o o t is s t r o n g l y r e m i n i s c e n t o f t h e a r g i l l i t e s  the S u s t u t 2 cm.  Copper d e p o s i t .  ( f i g . 23).  red i n c o l o u r and show e x t e n s i v e mud-  The rare green ones a r e not mud-cracked.  are seen almost e q u a l l y as tops  T h e i r presence and a s s o c i a t e d mudcracks near  the top o f the MoosevaJe, i n d i c a t e  a. gradual  and p e r i o d i c re-emergence o f these  rocks  to s u b a e r i a l weathering as the T r i a s s i c p e r i o d c l o s e d .  3.3.6  Shale  that john,  Unit  d i s t i n c t i o n between s h a l e s and a r g i l l i t e s  the s h a l e s have d e f i n i t e c l e a v a g e 1975).  The o n l y s h a l e s , thus  in c o l o u r and a r e f o s s i 1 i f e r o u s . (H.W. T i p p e r ,  to bedding  (Petti-  d e f i n e d , on the p r o p e r t y a r e those a t the  The f o s s i l s  These s h a l e s a r e dark  present  1978, p e r s . comm.) as the pelecypod,  Upper T r i a s s i c age f o r t h i s u n i t .  i s based on the c r i t e r i a  or parting parallel  top o f the lower u n i t o f the Moosevale Formation.  The s h a l e s  0.08 t o 0.04 mm g r a i n s o f f e l d s p a r , with able  These mudstones  to a graded bedding sequence, o r s i t t i n g , non-  graded, w i t h i n the conglomerates,  The  rock t o  T h e i r t h i c k n e s s e s a r e seldom g r e a t e r than 5 mm to  These rocks a r e very dominantly  cracking  i n DDH 110.  i n the upper 30 m o f the host  A r g i l l a c e o u s mudstones a r e p r e s e n t  levels  have been  black  identified  Hal obi a and i n d i c a t e an  themselves, c o n s i s t o f  r a r e a u g i t e g r a i n s , in an u n i d e n t i f i -  matrix.  3-3-7 Limestone U n i t Aside  from rare limestone  clasts,  the o n l y  the p r o p e r t y was i n DDH 47 i n the South Zone. so f a r r e p o r t e d ly f o s s i l s  in s i t u This  limestone  limestone  bed found on  bed i s the o n l y one  i n the uppermost p a r t o f the T a k l a Group i n t h i s a r e a .  have been seen o n l y  i n the lower u n i t o f the Moosevale b e f o r e  Previousreap-  53  F i g u r e 23:  Mud c r a c k s  in a r g i l l a c e o u s  mudstone.  •  F i g u r e 24:  Limestone r e e f in d r i l l  h o l e 47.  fine fossil  fragments v i s i b l e i n the l i m e s t o n e and a l s o  the upper c o n t a c t ( t o r i g h t ) where l i t h i c w i t h the l i m e s t o n e .  Note the  c l a s t s are intermixed  T h i s p i e c e o f c o r e i s about 1 f t  long.  pearing this  i n the Lower J u r a s s i c H a z e l t o n Group.  l i m e s t o n e bed i s a t the 120 f o o t l e v e l  of a fining-upwards  v o l c a n i c l a s t i c rock.  The base o f  o f DDH k~j where i t r e s t s on top  From 120.5  to 120.ft.  l i m e s t o n e w i t h abundant s h e l l d e b r i s , f r o m 120 t o 117-8 clasts this  a r e mixed in u n t i l  bed.  the l i m e s t o n e f i n a l l y  Thus the g e n e r a l  h i s t o r y appears  i t is  f t . typical  disappears.  t o be t h a t the l i m e s t o n e was  i n t o the d e p o s i t i o n a l a r e a w i t h r e s u l t a n t  The f o s s i l s  present  i n c l u d e (Appendix  II:  volcanic  F i g u r e 2k shows  down d u r i n g a p e r i o d o f q u i e s c e n c e w h i c h ended w i t h the g r a d u a l of c l a s t s  pure  laid  reintroduction  r e w o r k i n g and b r e c c i a t i o n .  GSC r e p t . 4-BEBC-78), s h e l l  frag-  ments, sponge s p i c u l e s , a f i s h t o o t h and a c r i n o i d columnal f r a g m e n t .  These  t y p e s o f l i m e s t o n e s a r e found o n l y  never  i n the Lower J u r a s s i c ,  i n t h e h i g h e r Upper T r i a s s i c  i n the c o m p l e t e T a k l a - H a z e l t o n Group a r e a s  1978,  pers.  3.3.8  B a s a l t i c Dyke U n i t  (H.W.  fashion  ( f i g . 2 5).  This  regular  dyke can be t r a c e d a l l a c r o s s  and  the N o r t h  i n a n o r t h e a s t e r l y d i r e c t i o n from the c i r q u e - f a u l t ( t h a t d i v i d e d the i n t o the N o r t h and South Zones) b e f o r e b e i n g Cliffs. entire  The t h i c k n e s s o f t h i s dyke length.  i;n t h e N o r t h Zone.  the south  is  lost  remarkably c o n s i s t e n t  150 m and a p p a r e n t l y  o f j o i n t s and f a u l t s . i n d i c a t i n g postdyke  length)  throughout  c h i l l e d margins  seen  i s not n e a r l y as c o n t i n -  Dyke m a r g i n s ,  i n p l a c e s , a r e marked by  to zones  slickensides  shearing. in colour.  Dark a u g i t e  up t o 2 mm i n d i a m e t e r , and w h i t e f e l d s p a r c r y s t a l s  are v i s i b l e .  is  its  concentrations of c r o s s - c u t t i n g  In o u t c r o p the dyke i s dark g r e e n i s h - b l a c k phenocrysts,  deposit  The reason f o r the d i s c o n t i n u i t y o f the dyke  i s d i s r u p t i o n caused by l o c a l  Zone  i n b l o c k s near the N o r t h  On the s o u t h e r n s i d e o f the c i r q u e - f a u l t , the dyke  i n t e r m i t t e n t l y over a distance of uous as  Tipper,  comm.).  A 2 m w i d e dyke c u t s t h r o u g h - t h e N o r t h Zone w i t h i n v a r y straight  rocks,  A 3 cm wide c h i l l e d margin  is present  a r e very f i n e - g r a i n e d and p a l e grey  c r y s t a l s up t o 1 mm in s i z e .  Also  (<  locally.  1 mm i n These  in c o l o u r w i t h a u g i t e  r a r e , 3 t o 5 cm t h i c k o f f s h o o t s o f t h e dyke  55  Figure wall  25:  rock.  plate.  Basaltic  dyke o f N o r t h  The  is the dark  dyke  Zone i n c o n t a c t w i t h  grey  C a r b o n a t e and e p i d o t e v e i n l e t s  t h e d y k e and c o u n t r y  rock.  material occur  conglomerate  on t h e l e f t  along  o f the  the c o n t a c t of  56 a r e seen t o i n t r u d e the e n c l o s i n g v o l c a n i c l a s t i c r o c k s . Petrographica11y subhedral  t h e dyke i s a b a s a l t which c o n s i s t s  p l a g i o c l a s e phenocrysts  o f 10 t o 30 p e r c e n t  and g l o m e r o p o r p h y r i t i c masses, and 5 to 10  p e r c e n t anhedral a u g i t e g l o m e r o p o r p h y r i t i c masses i n a groundmass o f subhedral t o a n h e d r a l p l a g i o c l a s e l a t h s w i t h i n t e r g r a n u l a r a u g i t e and opaque  grains.  S u b o p h i t i c t e x t u r e s a r e p r e s e n t t o some degree  The An  c o n t e n t o f the f e l d s p a r p h e n o c r y s t s margins mass.  smaller phenocrysts  i n t h e groundmass.  v a r i e s from An^Q t o A n ^ .  In t h e c h i l l e d  o f a u g i t e and f e l d s p a r a r e s e t i n a g l a s s y  Comparable dyke m a t e r i a l  i s p r e s e n t a t the 119-121.5 f t depth  ground-  interval  i n DDH 132. C h e m i c a l l y the dyke i s a l k a l i Sustut  deposit  basalt  ( f i g . 12)  i s a p p a r e n t l y s i m i l a r t o a group o f b a s a l t and g a b b r o i c  w h i c h i n t r u d e the o v e r l y i n g H a z e l t o n Group rocks (B.N. C h u r c h , 1978, p e r s . comm.). appears  The dyke seen on the dykes  immediately to the south  Thus, on g e o l o g i c a l grounds,  t h e dyke  t o be o f post Lower J u r a s s i c a g e .  3.3-9 M y l o n i t e U n i t  only  Although f a u l t i n g is l o c a l l y  i n t e n s e on the p r o p e r t y , m y l o n i t e i s found  i n the 305 313.4 f t i n t e r v a l  o f DDH 13-  -  Here the c o r e i s b l e a c h e d and  h i g h l y a l t e r e d t o c h l o r i t e , c a r b o n a t e , q u a r t z and l i m o n i t e . p r e s e n t as s l i c k e n s i d e s c u t t i n g through the r o c k .  i s seen throughout  intense  Types  from the base o f the Upper Member o f the Moosevale  a t i o n were a n a l y s e d f o r Z n , Cu, N i , S r , Rb (Table 3)110J3  Local  the p r o p e r t y .  3.3-10 Background C h e m i s t r y o f Some Rock Four samples  is  F a u l t gouge i s p r e s e n t a t  t h e head o f the c i r q u e between the North and South Zones. s1ickensiding  The c h l o r i t e  Samples  a r e from the bottoms o f DDH s 88 and 110 r e s p e c t i v e l y . 1  Form-  88N4 and Sample SILT i s  from t h e s h a l e a t the top o f the lower member o f the Moosevale and sample AGGL i s from the bottom o f the upper member.  Cu c o n t e n t s a r e h i g h  and S I L T , moderate i n 110J3 and low i n AGGL.  However,  ranging  i n 88N4  from 18 t o  TABLE I I I TRACE ELEMENT ANALYSES FOR DEEP SAMPLES (ppm + p r e c i . s i o n )  SAMPLE NO.  Zn  C_u  Sr_  AGGL  123.33(^1.68)  18.24(10.15)  30.11(±0.43)  509.05(±0.99)  69.56(+0.68)  SILT  65.80 (+1 .10)  132.83(-26.63)  0.00  563.69(+0.76)  40.5(±0.M)  88N4  109.02(10.10)  139.08(±29.87)  6.66(to.309)  190.16(+0.13)  8.97(Io.48)  "0J3  98.73 (+1 .46)  10.89(±0.39)  21 3.55( 0.31)  56.44(+2.43)  +  26.27( 0.01) +  58 140 ppm, the copper c o n t e n t s appear t o f a l l  w i t h i n the range o f e x p e c t e d  background v a l u e s as d e t e r m i n e d from the v o l c a n i c c l a s t s .  Zn i s h i g h e s t  AGGL, e q u i v a l e n t  is r e l a t i v e l y  i n _ 8 8 N 4 and 110J3, and lower i n S I L T . N i  c o n s t a n t , but v e r y  Low i n SILT.  Sr i s h i g h e s t  in the o t h e r two.  Rb has a l a r g e v a r i a t i o n , but g e n e r a l l y shows the same  in  i n SILT and AGGL, and lower  d i f f e r e n c e s as i n t h e c l a s t s . T a b l e 4 has t h e p a r t i a l  major o x i d e a n a l y s e s  f o r sample 88N4.  The v a l u e s  p r e s e n t a r e much the same as i n the v o l c a n i c c l a s t s and they show t h a t sample  i s not g r e a t l y metamorphosed  morphic  this  (see 4.7 E l e m e n t a l C h e m i s t r y o f M e t a -  Zones).  The h i g h but v a r i a b l e 18 t o 175 ppm, background copper c o n t e n t s found i n t h i s study,  f o r v o l c a n i c c l a s t s and o t h e r rock t y p e s , has a l s o been shown by  Hoffman (1977).  Hoffman s t u d i e d the copper v a l u e s  t i o n s o f t a l u s from t h e g e n e r a l area o f t h e S u s t u t copper  i n streams and f i n e Copper d e p o s i t .  He found  v a l u e s o f up t o 235 ppm i n streams and 450 ppm i n the t a l u s f i n e s . -•  These f i n e f r a c t i o n v a l u e s  3.4 D i s c u s s i o n 3.4.1 Sedimentary Bedding  had a mean o f 120 ppm.  o f t h e D e p o s i t i o n o f the V o l c a n i c l a s t i c Sequence Structures  i n s u r f a c e exposures  and d r i l l  c o r e s has a n o r t h w e s t e r l y s t r i k e  and a g e n t l e s o u t h w e s t e r l y d i p , w i t h some s m a l l v a r i a t i o n s property. average  frac-  i n d i p a n g l e on the  At the n o r t h e r n end o f the.map area (_|_e_. t h e North C l i f f s )  dips  10" a t t h e s o u t h e r n edge (J_e. near DDH 132) the d i p s a r e 20 t o 2 5 ' ,  and f u r t h e r t o the s o u t h , .steepen t o 55 t o 60* ( H a r p e r , from n o r t h t o south a r e g r a d a t i o n a l and u n i f o r m .  1977).  Changes i n d i p  Local v a r i a t i o n s do o c c u r  due t o the c r o s s - b e d d e d n a t u r e o f some o f the v o l c a n i c l a s t i c s .  Church  ascribes  to a gentle  the d i p v a r i a t i o n s , between the n o r t h and s o u t h a r e a s ,  m o n o c l i n e which has an a x i s o f 167* and a plunge o f 14*SE.  (1973)  TABLE  MAJOR  OXIDE  ANALYSES  ON S A M P L E  OX 1 DE  {%)  S i 0  45.00  Ti0 Al  2  0  2  *  2  3  Fe *  16.72 4.49 0.17  MgO  5.00  CaO  7.95  Na 0  3.91  K 0  1 .00  2  p o 2  5  0 . 64  L.O.I.  2 . 80  Cu  0.01  To t a 1  88N4  1 . 28  MnO  2  Total  IV  88.97  Fe and T i 0 ^ are low because t i t a n i f e r o u s m a g n e t i t e  was not d i s s o l v e d c o m p l e t e l y i n the a n a l y t i c a l p r o c e d u r e . "''-•'""""These a n a l y s e s were made by Min-En L a b o r a t o r i e s , Vancouver, B.C..  North  60 Property scale f o l d i n g is absent.  F o l d s are e v i d e n t o n l y on a-  r e g i o n a l s c a l e w i t h d i r e c t i o n s as d e t e r m i n e d by Harper above  i n the r e g i o n a l  geology c h a p t e r ( s e c t i o n  (1977) and d e s c r i b e d  2.2):  The most predominant sedimentary s t r u c t u r e p r e s e n t o f the Moosevale  Formation i s g r a d i n g o f beds.  from 1 cm t o 5 rn in t h i c k n e s s . occur.  i n the upper member  Individual  graded beds  Complete t r a n s i t i o n s from l a h a r s t o  mudstones  In the deeper p o r t i o n s o f the upper member o f the Moosevale  r e p e a t e d graded beds are t y p i c a l . Tuffaceous  Cross-bedding These c r o s s - b e d s  interbeds.  F i g u r e 26  i s about 18 m t h i c k .  shows t y p i c a l  occur  grading of  t o 1 m in t h i c k n e s s .  and  Other, less  bedding and trough  typical,  structures  cross-bedding.  sandy i n t e r b e d s , between conglomerate u n i t s ,  occurred locally  weathered more r e a d i l y than are the c o n g l o m e r a t e s , y i e l d i n g i n d e n t a t i o n s the o u t c r o p 3.4.2  (fig.20  not  Another common s t r u c t u r e i s mud  D i f f e r e n t i a l w e a t h e r i n g o f the v o l c a n i c 1 a s t i c sediments has Tuffaceous  27).  A predominant pa 1 e o - c u r r e n t d i r e c t i o n i s  in red mudstones.  i n c l u d e c u t and f i l l  beds.  (fig.  in the sandy u n i t s o f the v o l canic1 a s t i c p i l e ,  c r a c k s found most commonly  rarely.  rather,  i s a l s o abundant t h r o u g h ' the M o o s e v a l e ' F o r m a t i o n  r e a d i l y v i s i b l e . a n d i n f a c t may not e x i s t .  present  Formation,  sandy u n i t s most g e n e r a l l y a r e p a r t s o f graded sequences  than d i s t i n c t l y s e p a r a t e  average 0.3  One such sequence  range  are in  ).  Stratigraphy A t t e m p t s were made a t d e f i n i n g an i n t e r n a l  the upper member o f the Moosevale  Formation.  s t r a t i g r a p h y and  T h i s s u b d i v i s i o n o f the  graphy c o u l d not be a c h i e v e d by r o u t i n e o u t c r o p mapping o r d r i l l as no marker h o r i z o n s o f any s i g n i f i c a n t a r e a l e x t e n t c o u l d be C o r r e l a t i o n s between d r i l l  subdividing  hole  stratilogging  identified.  h o l e s us.ing the computer-based c o r e logs were the  o n l y means by which t h i s a u t h o r c o u l d a r r i v e a t an adequate s t r a t i g r a p h y , c o r r e l a t i o n s even w i t h these logs proved to be too  but  ambiguous.  The method o f c o n s t r u c t i n g a s e c t i o n through the v o l c a n i c l a s t i c s  involved  F i g u r e 26:  T y p i c a l r e p e t a t i v e graded bedding sequence.  This view i s 3 rn a c r o s s .  F i g u r e 27:  Cross bedding i n t u f f a c e o u s  sandstone.  62 p r i n t i n g s t r i p l o g s o f chosen v a r i a b l e s p e r p e n d i c u l a r to s t r i k e , thus  (note the d r i l l  hole sections  represent true c r o s s - s e c t i o n s . )  are  f o r each  h o l e i n a p a r t i c u l a r s e c t i o n and c r o s s - c o r r e l a t i n g between the d r i l l F i g u r e 28 has one such s e c t i o n . divided into subunits  The v o l c a n i c l a s t i c c o n g l o m e r a t e s  on the b a s i s o f t h e i r c o l o u r .  c o l o u r a t i o n between d i f f e r e n t l e v e l s  holes.  cannot be  The d i f f e r e n c e s  i n the c r o s s - s e c t i o n s  bedding planes and are i n t e r d i g i t a t e d to a l a r g e d e g r e e .  drill  in  do not f o l l o w Some o f the t u f f -  aceous sandstones do s t a n d out as d i s t i n c t u n i t s , but even these p i n c h out and can not be c o r r e l a t e d a c r o s s  a section completely.  It was noted d u r i n g the l o g g i n g  t h a t the amount o f d i f f e r e n t c l a s t  types v a r i e d c o n s i d e r a b l y from one d r i l l  h o l e to a n o t h e r .  Basalts  are most  common fragment t y p e , but any o f the o t h e r types can become predominant given  interval.  On the b a s i s o f t h i s , c r o s s - h o l e  using  the dominant  doned.  c o r r e l a t i o n was a t t e m p t e d  l i t h i c c l a s t type v a r i a b l e ( i e . were t h e r e p e r i o d s , now  r e p r e s e n t e d by c o n t i n u o u s predominated).  in a  i n t e r b e d s , when d e t r i t a l  i n f l u x o f one type o f  clast  T h i s approach a l s o produced ambiguous r e s u l t s and was aban-  Thus, no c o r r e l a t i o n between h o l e s was found based on dominant  clast  types and an adequate s u b d i v i s i o n o f the upper member o f the Moosevale  Form-  a t i o n remains 3.4.3  elusive.  Depositional  Environment  The upper member o f the Moosevale s h o r e , marine b a s i n . o f the sequence  Formation was d e p o s i t e d i n a near  The c o n c e n t r a t i o n o f red mud-cracked s i l t s  near the top  i n d i c a t e d t h a t towards the end o f d e p o s i t i o n o f t h i s  the b a s i n underwent r e p e t a t i v e s u b a e r i a l exposure and submergence. ing o f the b a s i n was c y c l i c types).  At some p o i n t s  change  The  infill-  ( i n d i c a t e d by d i f f e r i n g predominances o f c l a s t  in t i m e , i n f i l l i n g p r a c t i c a l l y stopped and l i m e s t o n e  r e e f s developed d u r i n g t h e s e p e r i o d s o f q u i e s c e n c e . a progressive  unit,  Detritus also  indicates  i n the chemical nature o f v o l c a n i s m w i t h i n the a r e a , as  shown by i n c r e a s e o f a n d e s i t i c components o v e r the c o n t e n t s o f lower  regions  CONGLOMERATE  mi  GREEN  CONGLOMERATE  SANDSTONE SECTION  F i g u r e 28: Stratigraphic cross-section. Numbered v e r t i c a l l i n e s a r e diamond d r i l l is along s e c t i o n l i n e O C (see a t t a c h e d g e o l o g y ma~p). 1  holes.  C-C  This  section  i n the s t r a t i g r a p h y  (Church,  i n d i c a t e some l o c a l  reworking o f t h e d e p o s i t e d sediments d u r i n g  periods.  The member,  1973)-  Cross-bedding  in fact, consists  and c u t and f i l l  Fossils,  (shown by the  subunits).  c o l l e c t e d by t h i s w r i t e r (_i_e. W1009, d e s c r i b e d i n Appendix I I ) ,  i n d i c a t e t h a t the age o f d e p o s i t i o n i s o l d e r t h a n . p r e v i o u s l y Monger (1977)  quiescenct  o f a s e r i e s o f i n t e r d i g i t a t e d and  i n t e r b e d d e d f a c i e s types which have i r r e g u l a r a r e a l e x t e n t s lack of d e f i n e a b l e  t e n t a t i v e l y p l a c e d the Savage Mountain-Moosevale  the K a r n i a n - N o r i a n  time boundary o f the Upper T r i a s s i c .  thought. c o n t a c t on  However, the f o s s i l s  from o v e r 600 m above the base o f t h e upper member o f the Moosevale are Late K a r n i a n - e a r l y N o r i a n i n age. sional)  structures,  Formation  T h e r e f o r e , the a c t u a l time (and e r o -  gap between the c e s s a t i o n o f T a k l a Group d e p o s i t i o n (_j_e_. the t o p o f  the Moosevale  Formation) and the s t a r t o f H a z e l t o n Group d e p o s i t i o n i s p r o b -  a b l y g r e a t e r than p r e v i o u s l y  envisaged.  65 CHAPTER 4: METAMORPHIC PETROLOGY AND WHOLE ROCK TRACE ELEMENT CHEMISTRY  4 . 1 1 n t r o d u c t ion Metamorphic  (or a l t e r a t i o n ) m i n e r a l s p r e s e n t  i n the S u s t u t  rocks,  i d e n t i f i e d by p e t r o g r a p h i c study w i t h some X - r a y d i f f r a c t i o n c o n f i r m a t i o n , i n c l u d e ; chlorite  (both p e n n i n i t e and c l i n o c h l o r e ) , c a r b o n a t e (mainly c a l c i t e w i t h very  rare s i d e r i t e ) , epidote, quartz, p r e h n i t e , s e r i c i t e , pumpellyite, a l b i t e , h e m a t i t e , z o i s i t e , phene, and p y r o l u s i t e .  Ramage  U974)  i n c l u d e d p y r i t e as an  alteration mineral. The above m i n e r a l o g y  i s c o n s i s t e n t w i t h the p r e h n i t e - p u m p e l l y i t e f a c i e s  metamorph i srn d e f i n e d f o r t h e upper member o f the Moosevale Sustut  Deposit  (Burns,  Formation on the  1973).  The most s i g n i f i c a n t form o f secondary m i n e r a l i z a t i o n i s as cement i n the groundmass o f t h e v o l c a n i c l a s t i c r o c k s . nebulous  Secondly,  t h e m i n e r a l s o c c u r as  p a t c h e s t h a t r e p l a c e a r e l a t i v e l y f i n e - g r a i n e d f r a c t i o n o f t h e host  r o c k , b u t do s p r e a d  into coarse f r a c t i o n c l a s t s  ( i e . metadomains).  importance a r e v e i n s , made up o f t h e above assemblages, host  rocks.  4.1.1  t h a t c u t through the  Metamorphic m i n e r a l s o c c u r w i t h i n t h e l i t h i c v o l c a n i c c l a s t s a f t e r  the groundmasses; they f i l l  Next i n  where they p r e f e r e n t i a l l y r e p l a c e primary m i n e r a l o g y ,  and/or  v e s i c l e s as amygdules.  Chlorite P e n n i n i t e and c l l n o c h l o r e commonly r e p l a c e v o l c a n i c c l a s t s .  most common i n amygdules, present chlorite  Penninite is  more so than c l i n o c h l o r e , but both c h l o r i t e s may be  i n the same amygdule, one as rims t o t h e o t h e r . r e p l a c e s g l a s s y groundmasses,  A s i d e from amygdules,  i s pseudomorphic a f t e r a u g i t e and h o r n -  b l e n d e , and r e p l a c e s s p e c i f i c zones w i t h i n zoned p l a g i o c l a s e  phenocrysts.  A u g i t e and h o r n b l e n d e w i t h opaque h e m a t i t i c rims commonly have c o r e s  66 of f i b r o u s  clinochlore.  In the dyke r o c k s , c h l o r i t e has  a u g i t e and both p l a g i o c l a s e and a u g i t e  r e p l a c e d groundmass  phenocrysts.  In the v o l c a n i c l a s t i c rocks as a w h o l e , c h l o r i t e m a i n l y o c c u r s e x t e n s i v e cement to the c o n s t i t u e n t g r a i n s .  If another cement i s  then c h l o r i t e can o c c u r as patches w i t h i n the m a t r i x . r e p l a c e s a u g i t e and small on f r a c t u r e s . drill  holes,  Chalcopyrite  l i t h i c grains.  These s l i c k e n s i d e s and in p l a c e s  indicate that strong  Alternatively, chlorite  a t i o n m i n e r a l as  i t is s u b s i d i a r y  slickensides  i n deeper p o r t i o n s o f some  f a u l t i n g or j o i n t i n g occurred.  i s smeared out on some s l i c k e n s i d e d s u r f a c e s .  copper s u l p h i d e - m i n e r a l i z e d a r e a s ,  dominant,  C h l o r i t e a l s o o c c u r s as  become important  as  c h l o r i t e loses  its  W i t h i n the h e a v i l y  importance as an a l t e r -  in q u a n t i t y to other m i n e r a l s .  Pyrite  is  the major s u l p h i d e m i n e r a l found w i t h c h l o r i t e ; c h a l c o p y r i t e can be i n t e r grown w i t h c h l o r i t e .  C h l o r i t e is extremely r a r e  in v e i n l e t s , or m i c r o v e i n -  lets. 4.1.2  Carbonate Carbonate  absent.  very abundant  i n the l i t h i c c l a s t s ;  The dominant o c c u r r e n c e o f c a r b o n a t e  have.chloritic ches  isn't  rims)  i s as amygdules  and as s m a l l v e i n l e t s c u t t i n g c l a s t s .  a f t e r large augite c r y s t a l s .  r e p l a c e d f e l dspars, m a i n l y  in i r r e g u l a r  The main o c c u r r e n c e o f c a r b o n a t e bonding  (some o f which It a l s o  the l i t h i c c l a s t s  forms  patis  patches  this  mineral  patches. i s as  cement  ( f i g . 2 9 ' ) , o r as p o r e - f i l l i n g in the m a t r i c e s .  type o f cement i s more dominant  These v e i n s  In dyke rocks  in the conglomerates  than-any o t h e r  ent cement types may be i n t e r g r o w n ) . ate.  locally  Carbonate can o c c u r as  w i t h i n the groundmasses o f some v o l c a n i c c l a s t s .  This  is  t h a t r e p l a c e p o r t i o n s o f p l a g i o c l a s e and a u g i t e c r y s t a l s , and l o c a l l y  pseudomorphic  has  it  (although  various  differ-  Veins are another major form o f  carbon-  range from m i c r o v e i n l e t s o f 2 to 3 mm w i d t h to the  v e i n s o f up to 15 cm in w i d t h , v i s i b l e  in outcrop.  Large-scale  large  carbonate  v e i n s most o f t e n c o n t a i n some q u a r t z , e p i d o t e and/or p r e h n i t e , though  there  67  F i g u r e 29:  Carbonate cement to l i t h i c v o l c a n i c  T h i s photomicrograph  F i g u r e 30:  (plane-polarized)  is about  T y p i c a l metadomain form of e p i d o t e .  grains. 1.1  cm a c r o s s .  The  e p i d o t e has p r e f e r e n t i a l l y r e p l a c e d the f i n e f r a c t i o n t h i s conglomerate.  T h i s view i s about 1 m a c r o s s .  in  68 a r e some ' p u r e '  carbonate v e i n s .  Some o f these v e i n s c o n t a i n  Carbonate i s p a r t i c u l a r l y abundant  sulphides.  i n areas o f copper m i n e r a l i z a t i o n .  Epidote  4.1.3  In a l m o s t a l l o f the v o l c a n i c c l a s t s , e p i d o t e o c c u r s m a i n l y as a l t e r a t i o n o f the groundmass.  Mostly  the e p i d o t e ( w i t h minor sphene)  mass through the groundmass, but o c c a s s i o n a l l y occur.  l a r g e r , more c r y s t a l l i n e , g r a i n s  In groundmasses w h i c h c o n t a i n f e l t e d masses o f f e l d s p a r l a t h s , e p i d o t e  grains  can be i n t e r s t i t i a l  t o the l a t h s .  in p l a g i o c l a s e p h e n o c r y s t s . i n some amygdules the  is a cryptocrystal1ine  amygdule.  augite  Epidote grains  form d i s c r e t e patches  Well developed, l a t h - l i k e epidote c r y s t a l s occur  but are l e s s abundant than o t h e r a l t e r a t i o n m i n e r a l s  that  E p i d o t e a s s o c i a t e d w i t h c h l o r i t e and/or c a r b o n a t e r a r e l y a l t e r s  grains. In o u t c r o p e p i d o t e i s the most o b v i o u s o f a l l metamorphic m i n e r a l s  of  fill  i t s d i s t i n c t i v e colour; and l o c a l  c o n c e n t r a t i o n i n patches o r  These metadomains are patches o f e p i d o t e which f i l l matrix grains  o f the h o s t  host.  Sizes  metadomains. and r e p l a c e  r o c k s , w i t h the end r e s u l t t h a t l i t h i c c l a s t s  l e f t surrounded by an e p i d o t e mass ( f i g . 30). elongate, parallel  open spaces  because  are  These metadomains a r e g e n e r a l l y  t o bedding and r e s t r i c t e d to s p e c i f i c i n t e r b e d s w i t h i n the  vary from s m a l l e r p a t c h e s , 0.3  by 5 cm, t o l a r g e s c a l e  replacements  o f b e d s , such as a t W8, where the metadomain is t h i c k e r than 2 m and has a lateral  dimension o f o v e r 60 m.  These metadomains appear to be an i n s i t u  development, however a r e l a t i o n s h i p w i t h v e i n s  is present  i n p l a c e s where t h e  metadomain can be veiwed i n t h r e e d i m e n s i o n s .  It seems t h a t v e i n s  i n t e r s e c t the  metadomain i n t e r b e d , thus the f l u i d s which formed the v e i n f l o w e d i n t o a d e f i n e d i n t e r b e d and a l t e r e d the h o s t through  rock.  F i g u r e 31 shows a c a r b o n a t e v e i n which c u t s  typica1" v o l c a n i c l a s t i c conglomerate but which a l s o has e p i d o t e  envelopes.  These envelopes a r e not v e i n m a t e r i a l , they a r e a l t e r e d ( e p i d o t i z e d )  host  T h i s a l t e r a t i o n i s due to f l u i d s t h a t formed the v e i n ,  rock.  i n t o and a t t a c k i n g the host  rock.  E p i d o t e metadomains o c c u r  spreading  irregularly  69  F i g u r e 31:  Carbonate v e i n s w i t h e p i d o t e e n v e l o p e s .  The c a r b o n a t e v e i n l e t i n the f o r e g r o u n d i s o n l y 2 t o 3 cm t h i c k but the e p i d o t e envelope i s up to 10 cm w i d e . c a r b o n a t e i n the background  i s k to 5 cm t h i c k .  e p i d o t e envelopes are a l t e r a t i o n o f the c o u n t r y  F i g u r e 32: WI 14.  The rock.  P r e h n i t e v e i n l e t swarm at sample l o c a t i o n  The  through  all drill  holes  to t h e i r bases.  e x t e n s i v e l y as v e i n m a t e r i a l , and/or  prehnite.  generally  m a t r i x o f the c o n g l o m e r a t e . intense,  dotized.  and  replacement and o v e r g r o w t h  i n the  In cases where the e p i d o t i z a t i o n has been  c l a s t s , as w e l l  d i f f e r e n c e s between e p i d o t e The e p i d o t e  partic-  as t h e i r m a t r i c e s , have a l l been e p i -  r o c k s a r e e x t e n s i v e l y overgrown  s u l p h i d e - r i c h zones.  quartz  sulphides.  In zones where o r e m i n e r a l s a r e c o n c e n t r a t e d ,  i n the host slight  lithic  as  occurs  intergrown w i t h carbonate,  These v e i n s may o r may not c o n t a i n  The metadomain e p i d o t e o c c u r s  ularly  Epidote also  individual  by e p i d o t e .  in r e g u l a r metadomains  There appear t o be and e p i d o t e  i n the ore zones has a h i g h e r  i s a d a r k e r green than i s the e p i d o t e i n metadomains  fragments  in  birefrigence,  c o n t a i n i n g no copper  mi nera1s . Zoisite  i s a minor m i n e r a l  i s c o n c e n t r a t e d and b e s t 4.1.4  i n t e r g r o w n w i t h e p i d o t e , where the e p i d o t e  developed.  Quartz Quartz  in c l a s t s  commonly o c c u r s  dominantly occurs  as c r o s s - c u t t i n g  i n i r r e g u l a r l y shaped pores  i n the groundmass  may be v e r y r a r e p r i m a r y q u a r t z ) o r an amygdules W i t h i n the dyke rocks q u a r t z  veins.  Quartz  (some o f  this  w i t h o t h e r gangue m i n e r a l s .  i s p r e s e n t o n l y as v e i n  material.  W i t h i n the c o n g l o m e r i t i c r o c k s , q u a r t z o c c u r s as cement, as p a t c h e s the m a t r i x ( p o r e s ) ,  o r as v e i n s .  a l t e r a t i o n m i n e r a l s , and i n some,  The q u a r t z  is  intergrown with other  sulphide minerals are present.  most common as cement i n s u l p h i d e - r i c h 4.1.5  in veins  in  Quartz  is  rocks.  P r e h n i te Prehnite content of v o l c a n i c c l a s t s  foregoing  four minerals.  groundmass.  amygdules  than t h a t o f any o f  r e p l a c e the groundmass p a r t i a l l y , be  (with c h l o r i t e . a n d / o r c a r b o n a t e ) , or  ( g e n e r a l l y w i t h some p u m p e 1 1 y i t e ) .  in dyke rocks o c c u r s  less  in  the  P r e h n i t e o c c u r s m a i n l y as v e i n s o r as p a t c h e s  P r e h n i t e can a l s o  morphic a f t e r a u g i t e  is  veins.  pseudo-  r a r e l y , occur  The o n l y p r e h n i t e  in a  in  recognized  71 Intergranular  cement, and v e i n s a r e the major forms o f p r e h n i t e i n the  host v o l c a n i c l a s t i c r o c k s . cement i t i s commonly  Although  p r e h n i t e is nowhere the dominant  intergrown w i t h other a l t e r a t i o n ' m i n e r a l s .  The v e i n  p r e h n i t e o c c u r s w i t h o t h e r gangue m i n e r a l s and s u l p h i d e s o c c u r l o c a l l y , i n these v e i n s . wide, v e i n l e t s  Pure p r e h n i t e v e i n s o c c u r s  in local  swarms o f t h i n , 2 to 5 mm  ( f i g . 32 shows one such s e t a t W114).  The best development o f  prehnite is w i t h i n s u l p h i d e - r i c h v o l c a n i c l a s t i c rocks. 4.1.6  S e r i c i te S e r i c i t e o c c u r s as an a l t e r a t i o n o f p l a g i o c l a s e p h e n o c r y s t s .  i z a t i o n of plagioclase  i s h i g h l y v a r i a b l e ; as some p l a g i o c l a s e has o n l y  i e n t s e r i c i t e , some i s very e x t e n s i v e l y a l t e r e d t o s e r i c i t e . mineral  is  The s e r i c i t incip-  This a l t e r a t i o n  r e s t r i c t e d t o p l a g i o c l a s e and does not o c c u r i n m a t r i x m a t e r i a l  or in v e i n s .  Because t h i s m i n e r a l  c a l l y a l l c l a s t t y p e s , anywhere  is  i n c i p i e n t l y developed through  in the upper Moosevale  practi-  section, s e r i c i t e  is  most l i k e l y a d e u t e r i c m i n e r a l . 4.1.7 Pumpel1y i t e Pumpellyite  in Sustut  rocks  i s a minor metamorphic m i n e r a l .  most commonly as s m a l l , n e e d l e - l i k e l a t h s m i n e r a l s , sometimes  It  is  i n t e r g r o w n w i t h o t h e r metamorphic  these needles a r e a r r a n g e d  in r a d i a t i n g masses.  p u m p e l l y i t e c r y s t a l s o c c u r i n groundmass a l t e r a t i o n s , amygdules ( w i t h o t h e r m i n e r a l s ) , and r a r e l y in v e i n s .  These  and patches  L o c a l l y p u m p e l l y i t e i s a minor  a l t e r a t i o n p r o d u c t o f a u g i t e and/or h o r n b l e n d e c r y s t a l s , and r a r e l y i t t o t a l l y pseudomorphic a f t e r hornblende  ( f i g . 33)-  i t e o n l y r a r e l y as needles a f t e r p l a g i o c l a s e Pumpellyite  i n t e r g r o w n as s m a l l  There i s more p u m p e l l y i t e p r e s e n t trations.  is  Dyke rocks have p u m p e l l y -  phenocrysts.  i s not abundant enough to form a cement i n the host  a t e s , but i s sometimes  seen  conglomer-  l a t h s w i t h o t h e r cementing m i n e r a l s .  in rocks which have s t r o n g s u l p h i d e c o n c e n -  In s u l p h i d e a r e a s , and r a d i a t i n g masses o f l a t h s are more common  and b e t t e r d e v e l o p e d .  72  F i g u r e 33:  P u m p e l l y i t e (green)  hornblende g r a i n s .  pseudomorphic  after  The l a r g e s t g r a i n i s .15 mm l o n g .  The c l a s t i s a f e l d s p a r porphyry  andesite.  73 4.1.8  Albite Albite  in c l a s t s occurs.most  phenocrysts. o f nebulous almost  In  i t s most  albitic  commonly as a replacement o f  i n c i p i e n t nature, t h i s a l t e r a t i o n takes  rims on the p h e n o c r y s t s .  t o t a l l y r e p l a c e d by a l b i t e .  monomineral1ic, or f i l l  plagioclase  amygdules.  the form  Other p l a g i o c l a s e g r a i n s  A l b i t e can a l s o form v e i n s , A l b i t e in the dyke m a t e r i a l  are  usually replaces  plagioclase. A l b i t e can o c c u r as a r a r e cement, but i t i s never abundant enough to form a major component of small e x t e n t .  There  in cementation.  A l b i t i c veins  are monominera11ic  i s no observed c o n c e n t r a t i o n o f a l b i t e i n areas  s u l p h i d e m i n e r a l i z a t i o n . Where p r e s e n t a l b i t e i s an a l t e r a t i o n a f t e r clase  only.  4.1.9  Hemat i t e Hematite is ubiquitous  rich or not.  thoughout  clasts  T h i s m i n e r a l o c c u r s as d u s t i n g s  chlorite), clasts,  (where the  i s t o t a l l y a l t e r e d , the h e m a t i t e i s an o u t e r rim t o  a l t e r a t i o n products o f a groundmass o r m a t r i x , as o u t e r rims  and as cement to l i t h i c g r a i n s .  h e m a t i t e i s v e r y abundant or  sulphide-  phenocrysts,  complete o u t e r rims on some l a r g e a u g i t e and hornblende p h e n o c r y s t s a u g i t e or hornblende  of  plagio-  i n c o n g l o m e r a t e , whether through p l a g i o c l a s e  and  as a secondary  In areas w i t h high s u l p h i d e mineral  on  content,  intergrown w i t h o t h e r gangue,  in i n t e n s e l y a l t e r e d p l a g i o c l a s e .  4 . 1 . 1 0 Sphene Sphene o c c u r s  i n minor amounts w f t h e p i d o t e a l t e r a t i o n .  m a i n l y w i t h the e p i d o t e t h a t a l t e r s c l a s t s and i s appearance o f these a l t e r a t i o n s .  It  is  found  the reason f o r the t u r b i d  Sphene a l s o o c c u r s w i t h o t h e r gangue m i n e r a l s  ( e s p e c i a l l y c a r b o n a t e ) where complete replacement o f m a g n e t i t e o c c u r s sphene  probably  epidote is  rare.  takes up the t i t a n i u m from the a l t e r e d m a g n e t i t e s ) .  i s . c l e a r e r and b e t t e r c r y s t a l l i z e d i n s u l p h i d e - r i c h a r e a s ,  (the Where  sphene  74 4.1.11 P y r o l u s i t e Pyrolusite strongly  i s found on c a r b o n a t e f r a c t u r e s and v e i n s .  It  i s most  d e v e l o p e d where the f r a c t u r e s o c c u r i n the s u l p h i d e - r i c h a r e a s .  D e n d r i t i c habit is often present.  4.2 Metamorphic  Reactions  The g r e a t e s t c o n c e n t r a t i o n s o f metamorphic m i n e r a l s a r e s i m p l e open space f i l l i n g s . Minerals  These  i n c l u d e cements, v e i n s , pore f i l l i n g s , and  i n these forms have o b v i o u s l y  from c i r c u l a t i n g s o l u t i o n s .  amygdules.  been i n t r o d u c e d by, and p r e c i p i t a t e d  These m i n e r a l s are more o r l e s s  in e q u i l i b r i u m  w i t h each o t h e r , e x c e p t t h a t some minor c h l o r i t e o f p r o b a b l e d e u t e r i c o r i g i n has been overgrown and r e p l a c e d by l a t e r p r e h n i t e , p u m p e l l y i t e and/or e p i d o t e W i t h i n the c l a s t s though, metamorphic m i n e r a l s are d e v e l o p e d as a t i o n s and replacements o f p r e - e x i s t i n g m i n e r a l s . somewhat g e n e r a l  These r e a c t i o n s have a  form such t h a t c e r t a i n elements are r e l e a s e d p r e f e r e n t i a l l y  from the d e g r a d a t i o n o f a p r e - e x i s t i n g m i n e r a l .  The c h l o r i t e s  and c l i n o c h l o r e ) a r e a low i r o n type (Deer e_t_ a j _ . , 1974). ite  (Mg^Al gFe  '((Al.Fep  ) ) x  1  (Si  3  2  0 g)9 (0H)g) 1 0  and hornblende  replacement o f a u g i t e  ( C a (Mg, Fe, A l )  reaction. Si0  2  (OH) ((S i ,A1 ^  2  a l m o s t equal c o n t e n t s o f Mg and Fe, Fe i s the c h l o r i t e .  alter-  2  (penninite  Thus i n the c h l o r (Ca(Mg,Fe)(Si0 1  2  2  ) ) ) , which have 2  r e l e a s e d and the Mg i s  Ca, and Si a r e a l s o r e l e a s e d , whereas H 0  )  t a k e n up i n  i s consumed by the  The Fe p r o b a b l y appears as h e m a t i t e , the Ca as c a r b o n a t e , and the  as q u a r t z and p o r t i o n s o f these t h r e e elements are combined to form  e p i d o t e as  is  H 0. 2  Development o f e p i d o t e (Ca'FeAl 0.0H (S i 0 ^ ) (S iO^)) and p r e h n i t e 2  ( C a A l S i ^0.| g) (OH) ) 2  2  a f t e r the f e r ro-magnes i urn- r i ch groundmass (_i_e. composed  o f abundant a u g i t e and hornblende) cium and w a t e r .  2  l e d to a r e l e a s e o f  A l b i t i z a t i o n of p l a g i o c l a s e  i r o n and uptake o f c a l  involved expulsion of calcium.  75 Thus where a l t e r i n g f l u i d s have r e a c t e d w i t h w a l l and s i l i c a a r e r e m o b i l i z e d from o r i g i n a l  minerals,  rock,  sometimes  iron,  calcium  resulting  the f o r m a t i o n o f h e m a t i t e , c a r b o n a t e and s i l i c a o r the more h y d r a t e d  in  minera  e p i d o t e , p r e h n i t e and p u m p e l l y i t e .  A.3 Metamorphic M i n e r a l The metamorphic m i n e r a l s  Assemblages present  in the S u s t u t  rocks  can be grouped  in  a number o f s t a b l e assemblages ( s t a b l e assemblages i m p l i e s t h a t the m i n e r a l were found  i n c o n t a c t and appear to be i n e q u i l i b r i u m ) .  a r e somewhat distinct  different  isogradal  in v a r i o u s  divisions  p a r t s o f the Moosevale F o r m a t i o n , but no  were i d e n t i f i e d .  w i t h i n the l i t h i c v o l c a n i c c l a s t s  S t a b l e assemblages  are:  1)  carbonate-chlorite-prehnite  2)  carbonate-prehnite-quartz  3)  c h l o r i t e - c a r b o n a t e - p u m p e l l y i te  4) c h l o r i t e - c a r b o n a t e - : q u a r t z 5)  chlorite-pumpel1yite  6)  epidote-carbonate-quartz  7)  epidote-chlorite-carbonate  8)  epidote-chlorite-pumpe1lyite  9) epi d o t e - c h l o r i t e - q u a r t z - z o i s i te 10)  epidote-prehnite-quartz  11)  prehnite-pumpellyite  12)  prehnite-quartz-pumpellyite  Assemblages o c c u r i n g  i n the dyke rocks  include:  13)  chlorite-epidote-carbonate  14)  chlorite-epidote-quartz  15)  ep i d o t e - p r e h n i t e - c a r b o n a t e - q u a r t z - z o i s i te  16)  epidote-pumpe11yite  These assemblages  present  76 Metamorphic mineral in sulphide-poor  assemblages  conglomerates  found m a i n l y  interclast  material  are:  17)  carbonate-chlorite  18)  carbonate-chlorite-prehnite-pumpellyite  IS)  carbonate-chlorite-quartz  20)  carbonate-epidote-albite  21)  carbonate-epidote-zoisite  '22)  as  chlorite-prehnite  23) e p i d q t e - c h l o r i t e - z o i s i t e 2k)  epidote-prehnite  25)  epidote-prehnite-carbonate-pumpe11yite-zoisite  26) e p i d o t e - p r e h n i t e - c a r b o n a t e - z o i s i t e 27)  epidote-prehnite-chlorite  28)  epidote-prehnite-shlorite-carbonate  .23)  epidote-prehnite-quartz  30)  epidote-quartz  31)  epidote-zoisite  32)  prehnite-pumpellyite  33) q u a r t z - a - l b i t e Assemblages w i t h i n Ik)  i n t e r c l a s t material of s u 1 p h i d e - r i c h areas  carbonate-chlorite-quartz  35) c a r b o n a t e - c h l o r i t e - q u a r t z - a ' l bi t e 36)  carbonate-quartz-zoisite  37)  chlorite-carbonate-epidote  38)  chlorite-epidote-1imonite  3S)  epidote-carbonate-zoisite  ko) e p i d o t e - c h l o r i t e - c a r b o n a t e - a l b i t e  are:  77 41)  epidote-prehnite  42)  epidote-prehnite-carbonate  43)  epidote-prehnite-carbonate-quartz-pumpe1lyite  kk)  epidote-prehnite-carbonate-quartz-zoisite  k5)  epidote-prehnite-chlorite-quartz  46)  epidote-prehnite-pumpellyite  kl)  epidote-prehnite-quartz-zoisite  48)  epiddte-pumpel1ite  kS) e p i d o t e - z o i s i t e . 5O)  prehni t e - c h l o r i te-pumpellyi te  As can be seen t h e r e a r e some assemblages which o c c u r area. Also,  a l l assemblages a r e o f the same g e n e r a l  i n more than one  prehnite-pumpellyite  system. Some o f t h e above assemblages a r e e q u i v a l e n t r e p o r t e d e l s e w h e r e by o t h e r a u t h o r s . a study o f s u b - g r e e n s c h i s t  t o those t h a t have  For i n s t a n c e ,  metamorphism  i n Maine,  been  R i c h t e r and Roy (1974), i n d e s c r i b e d assemblages  simi-  l a r t o 1, 5, 17, 18, and 50 i n t h e i r p r e h n i t e - p u m p e l l y i t e zone, and the same assemblages as 8, 22, 27 and kl i n t h e i r p u m p e l 1 y i t e - e p i d o t e - a c t i n o l i t e J o l l y (1974) found assemblage 40 i n h i s p r e h n i t e - p u m p e l l y i t e a r e a . assemblages above a r e somewhat  s i m i l a r to others  r e p o r t e d by these  zone.  The o t h e r authors.  A l s o these assemblages a r e c o n s i s t e n t w i t h Coomb s (1960) d e f i n i t i o n o f the 1  prehnite-pumpellyite facies.  Therefore  the S u s t u t D e p o s i t  as b e i n g o f p r e h n i t e - p u m p e l l y i t e grade metamorphism, a c t i n o l i t i c facies  4.4  of  grading  towards  Metamorphism  (1973) has e s t i m a t e d t h a t l i t h o s t a t i c p r e s s u r e  upper Moosevale r o c k s , Thus i t w i l l  possibly  (due t o e p i d o t e and z o i s i t e ) .  Temperatures  Burns  rocks a r e d e f i n e d  by o v e r l y i n g  e x e r t e d upon t h e  f o r m a t i o n s , was on the o r d e r o f 3 k b .  be assumed t h a t the metamorphic m i n e r a l s  developed a t t h i s  pres-  78 sure. Liou  (1971) s t u d i e d and e x p e r i m e n t a l l y determined the s t a b i l i t y  relationships of prehnite. facies  The s t a b i l i t y f i e l d o f the p r e h n i t e - p u m p e l 1 y i t e  i s shown by f i g . 34 ( i b i d . , p..528).  L i o u s t a t e d t h a t the r e a c t i o n ;  2 l a u m o n t i t e = p r e h n i t e + k a o l i n i t e + 3 q u a r t z + 5 water i s the lower of the p r e h n i t e - p u m p e l l y i t e f a c i e s .  This  limit  r e a c t i o n i s p e r t i n e n t t o the T a k l a  Group system as Burns (1973) showed t h a t l a u m o n t i t e i s the i n d i c a t i v e metamorphic m i n e r a l  in overlying  rocks.  From f i g . 34 a t 3 kb p r e s s u r e ,  this  r e a c t i o n i s i n e q u i l i b r i u m a t about 300*C, t h e r e f o r e the S u s t u t  Deposit  morphism s h o u l d have o c c u r r e d a t t e m p e r a t u r e s e x c e e d i n g 300*C.  Liou  the upper  defined  l i m i t o f p r e h n i t e s t a b i l i t y by t h e r e a c t i o n ; 5 p r e h n i t e = 2 z o i s i t e  + 2 grossular  + 3 quartz + 5 water.  b r a t e s a t 403'C. grossular  meta-  A g a i n from f i g . 34, t h i s  reaction  equili-  Some z o i s i t e i s found i n the rocks o f the d e p o s i t but no  is present.  Therefore  i t can be assumed t h a t the metamorphism  occurred  below 403'C, but the presence o f z o i s i t e may i n d i c a t e t h a t the upper s t a b i l i t y l i m i t o f p r e h n i t e may have been v e r y s l i g h t l y e x c e e d e d . t h a t the metamorphism o f Moosevale  rocks  o c c u r r e d between 300' and 403"C, and most higher  underlying  Liou's  the S u s t u t  data  indicate  property  l i k e l y a t temperatures  towards the  1imi t .  F i g . 35, from Thompson (1971, p.86) , shows the s t a b i l i t y f i e l d s as d e t e r mined by Thompson f o r a n o r t h i t e , a l b i t e ,  laumontite, e t c . . A l b i t e , epidote,  p l a g i o c l a s e and q u a r t z a r e s t a b l e t o g e t h e r a t 3 kb p r e s s u r e w i t h above a p p r o x i m a t e l y 325'C. Sustut above  rocks,  further  temperatures  These same m i n e r a l s a r e i n e q u i l i b i r i u m i n t h e  i n d i c a t i n g t h e metamorphism o c c u r r e d  at temperatures  300'C. 4.5 Age o f Metamorphism  ly.  The age o f metamorphism w i t h i n the T a k l a rocks can be e s t i m a t e d o n l y  crude-  Read and E i s b a c h e r  Group  rocks,  (1973) d e t e r m i n e d t h a t metamorphism o f t h e S u s t u t  c o n f o r m a b l y above the T a k l a , o c c u r r e d  i n Eocene times  (49 t o 53 m . a . ) .  500 Temptrolure  F i g u r e 34: facies field  Stability  (from L i o u ,  in  *C  r e l a t i o n s o f the p r e h n i t e - p u m p e l l y i t e  1971, p. 5 2 8 ) .  i s shaded on t h i s  diagram.  The p r e h n i t e - p u m p e l l y i t e  60  Figure  35-'  S t a b i l i t y f i e l d s of  (from Thompson, 1971, S u s t u t Copper a r e  p. 86).  shaded.  albite-epidote-plagioclase-quartz The r e l e v a n t  s t a b i l i t y areas  for  81 S i n c e these  rocks a r e p a r t o f a sequence from the A s i t k a through  T a k l a Groups,  and s i n c e metamorphism i s g r a d a t i o n a l between a l l these groups, i t c o u l d be assumed t h a t the T a k l a Group metamorphism was synchronous w i t h t h a t o f the However, Burns ( 1 9 7 3 )  S u s t u t Group.  s t a t e s t h a t the metamorphism c o u l d a l s o  have been o f Lower J u r a s s i c age ( r e l a t e d t o t h e Omineca i n t r u s i o n s ) .  I f the  dyke i n t h e North Zone i s a c t u a l l y p a r t o f t h e i n t r u s i v e sequence o f b a s i c rocks c u t t i n g  the Lower J u r a s s i c sequence and i f metamorphism o f t h e p r o p e r t y  o c c u r r e d as a s i n g l e event then t h e age o f metamorphism has t o be p o s t Lower J u r a s s i c .  T h i s i s because t h e dyke i s found t o be c u t by  p r e h n i t e v e i n s and a l s o has the same g e n e r a l metamorphic a l t e r a t i o n as i t s host  rocks. 4.6  Elemental  Chemistry  o f Metamorphic Zones  T r a c e element a n a l y s e s f o r Zn, Cu, N i , S r , and Rb, and p a r t i a l major o x i d e a n a l y s e s were done f o r t h r e e s e t s o f samples. T a b l e s 5 and 6 . gross chemical  Analytical  data a r e i n  The samples w i t h i n each s e t were s e l e c t e d t o a s c e r t a i n i f any v a r i a t i o n s occur between zones w i t h metadomains o f metamorphic  m i n e r a l s and s u r r o u n d i n g  l e s s metamorphosed c o u n t r y  rock.  In t h e f i r s t s e t , W8A i s a sample o f v e r y s t r o n g l y e p i d o t i z e d rock and W8C i s o f a conglomerate j u s t below W8A, which i s r e l a t i v e l y and w h i c h c o n t a i n s v i s i b l e s u l p h i d e m i n e r a l i z a t i o n .  unmetamorphosed  Zn, Cu, and t o a minor  e x t e n t , Ni a r e s t r o n g e s t in W8C (due t o m e t a l l i c m i n e r a l i z a t i o n ) . o t h e r hand i s e n r i c h e d i n the metamorphosed r o c k . o x i d e d i f f e r e n c e s between the two o c c u r s  S r on t h e  The most s i g n i f i c a n t major  i n MgO, CaO, Na^O and v o l a t i l e s  (L.O.I.) as CaO i s g r e a t l y e n r i c h e d i n W8A, and the o t h e r o x i d e s a r e d e p l e t e d r e l a t i v e t o W8C.  Si0  2  and A 1 0 2  are a l i t t l e  lower  i n W8A a l s o .  W i t h i n t h e second s e t , samples 110D1 and 110D4 a r e o f f r e s h v o l c a n i c l a s t i c rock w h i c h b r a c k e t  110D3, which i s an e p i d o t e metadomain zone (110D1 i s above  110D3, 110D4 i s b e l o w ) .  Sr is e n r i c h e d and Zn i s d e p l e t e d i n the metadomain.  TABLE V TRACE ELEMENT ANALYSES FOR METAMORPHIC SAMPLES (ppm ± p r e c i s i o n )  SAMPLE NO.  Zn  W8A  38.58( 0.08)  W8C  96.00(±0.01)  110D1  146.56'( 17.54)  11003  +  Cu  Nj_  449-541 5.87) +  1288.39(  ± 1 6  5J5)  .15.80(+0.79) 21.66(12.14)  Sr.  J^.  1220.42(11.64)  4.41 (+0.05)  .260.15(10.78}  7.35(10.25)  9.50(18.25)  9.98( 0.64)  234.64(10.87)  7.30(±0.01)  26.47(10.37)  26.16(11.40)  6.86( l.l4)  1633.97(^2.19)  1.69(^0.37)  110D4  133.03(10.89)  21.18(10.33)  8.69(10.43)  354.63(10.83)  1.79(^0.05)  6A3  102.11(12.29)  283.06(±66.03)  29.29.(±0.50)  235.35(10.18)  22.95(10.43)  6A4  76.98(12.18)  65.13(10.96)  32.96(10.77)  611.10(±1.46)  3.55( 0.29)  6A5  74.93(11.14)  66.55(^0.51)  17.58(10.74)  170.26(10.66)  1*».88(±'0.31)  +  +  +  +  00  TABLE  VI  MAJOR OX IDE ANALYSES FOR METAMORPHIC SAMPLES {%)  SAMPLE NO. 1 1 OD 1 • • • ; • 110D3  110D4  6A3  6A4  6A5  55 .00  46 .00  44 .00  kk.25  47 .50  0. 93  0. 81  1 .41  0. 97  1. 05  0. 96  16 .60  18 .12  15 .40  18 .50  15 .94  16 .60  16 .30  k.36  3. 27  3. 92  2. 80  4. 69  3. 59  3. 51  3. 27  MnO  0. 17  0 . 14  0. 18  0. 12  0. 20  0. 19  0. 17  0. 15  MgO  1 .10  4.55  5. 85  0. 65  6. 15  6. 85  5. 45  5. 45  CaO  14 .70  6. 25  6. 25  15 .70  5. 80  9. 30  12 .15  8. 25  Na 0 2  1 .33  4. 80  3. 99  0. 63  4. 35  3. 43  3. 63  4. 40  K0  0 . 49  0 . 74  0. 62  0. 26  0. 37  1. 61  0. 35  1 .10  0. 40  0. 64  0. 97  . 0. 64  1. 05  0. 72  0. 48  : 0.81  L.O.I.  1. 10  3. 42  2. 87  0. 50  3. 06  2. 43  2. 22  1 .94  Cu  0 . 04  0. 13  -  03  0. 007  0. 007.  83.98  89.04  91.45  89.06  89.87  90.14  OXIDE S! o  Ti0  2  *  2  AI2O3 Total  Fe *  2  p o 2  5  Total  W8A  W8C  kk.75  47 .50  47 .75  0. 68  1 .00  14 .86  .  --  °-  92.51  91.58  1  CO  T o t a l Fe and T i O - a r e low because t i t a n i f e r o u s m a g n e t i t e was not d i s s o l v e d c o m p l e t e l y i n t h e a n a l y t i c a l procedure. &**5V**These a n a l y s e s were made by Min-En L a b o r a t o r i e s , North Vancouver, B.C..  8k Ni  i s constant  other  two.  ^2^5  the three.  Cu i s l o w e s t  Rb i s m o s t common i n 110D1.  most n o t a b l e Na^O,  among  a n c  variations  and e q u i v a l e n t  In t h e m a j o r o x i d e  i n the t h i r d  relative  to the unaltered  s e t , s a m p l e s 6A3 a n d 6A5 a r e r e l a t i v e l y  m o r p h o s e d s e d i m e n t b r a c k e t i n g 6Ak, an. e p i d o t e m e t a d o m a i n . and  Rb d e c r e a s e d  difference Cu v a l u e s  i n t h e metadomain.  is negligible. i n 6/\k a n d : 6 A 5 ,  background amounts. samples, except The most  Ni i s s l i g h t l y  Cu i s h i g h e s t  CaO i s h i g h e r  These v a r i a t i o n s  chemical  the elemental in  s e c t i o n k.3 a b o v e .  unmeta-  Sr i s increased i n 6A4, but t h e  i n 6 A 3 a n d Zn i s a l s o h i g h e r  do n o t h a v e s t r o n g v a r i a t i o n  in 6A3.  between t h e  i n CaO a n d S r (+ S i O ^ ) a n d d e c r e a s e i n  o f t h e metadomains  relative  to the country  rock.  i n t r o d u c t i o n o f C a - r i c h s o l u t i o n s (as  cement) and breakdown o f ferro-magnesiurn  chemistry  samples.  d i f f e r e n c e s between metadomains and c o u n t r y  are~consistent with  shown by c a r b o n a t e  MgO,  i n t h e metadomain.  r o c k c a n be s u m m a r i z e d a s ; i n c r e a s e MgO, A l ^ O ^ a n d Rb c o n t e n t s  Al^O^,  t h o u g h , a r e n o t d e p l e t e d a n d a r e c o n s i s t e n t as  The m a j o r o x i d e s  significant  higher  i n the  chemistry, the  a r e i n c r e a s e d S i O ^ a n d CaO, a n d d e c r e a s e d  ^ L.O.I, i n t h e metadomain  Likewise  i n 110D1  minerals.  i s c o n s i s t e n t with the r e a c t i o n hypotheses  Thus  put forward  85  CHAPTER 5: ORE HINERALOGRAPHY AND FORM  5.1  Introduction  A total  o f f o u r t e e n copper and i r o n m i n e r a l s , m a i n l y s u l p h i d e s ,  and minor amounts o f c a r b o n a t e s , have been i d e n t i f i e d in the S u s t u t Magnetite detrital  i s found as a p r i m a r y c o n s t i t u e n t grains.  rich magnetites. relatively grains,  oxides deposit.  in v o l c a n i c fragments and as  I l m e n i t e i s p r e s e n t m a i n l y as  intergrowths with titanium-  H e m a t i t e has two main forms: as a p r i m a r y m i n e r a l w i t h  low abundance  in v o l c a n i c s  rocks and f r a g m e n t s , and as  much l e s s common than the m a g n e t i t e s  ondary m i n e r a l e x t e n s i v e l y the more common s u l p h i d e s  and more i m p o r t a n t l y , as a s e c -  i n t e r g r o w n w i t h copper s u l p h i d e s .  Chalcopyrite is a  C h a l c o c i t e i s the most abundant copper s u l p h i d e and  forms the b u l k o f o r e c o n c e n t r a t i o n s N a t i v e copper o c c u r s  P y r i t e , one o f  p r e s e n t , g e n e r a l l y seems to be e p i g e n e t i c i n o r i g i n  a l t h o u g h some may p r e d a t e the main m i n e r a l i z i n g e v e n t . secondary m i n e r a l a l s o .  detrital  i n a s s o c i a t i o n w i t h l e s s abundant b o r n i t e .  i r r e g u l a r l y and i s not r e a l l y o f o r e g r a d e .  Digenite  is  p r e s e n t as r e p l a c e m e n t s o f b o r n i t e , and as e x s o l u t i o n p r o d u c t s o f c h a l c o c i t e and b o r n i t e .  C o v e l l i t e normally is  i n t e r g r o w n w i t h d i g e n i t e and b o r n i t e .  M a l a c h i t e , and r a r e r a z u r i t e , a r e p r e s e n t as sulphides.  Cuprite occurs  a l t e r a t i o n p r o d u c t s o f copper  r a r e l y as rims on g r a i n s o f n a t i v e c o p p e r .  L i m o n i t e appears as r a r e rims on c h a l c o p y r i t e .  The r a r e s t s u l p h i d e  i s g r e e n o c k i t e w h i c h i s found in cha1 c o p y r i t e - r i c h z o n e s .  present  No s p h a l e r i t e was  found in a s s o c i a t i o n w i t h g r e e n o c k i t e . Major s u l p h i d e o c c u r r e n c e s are r e s t r i c t e d to the upper 60 m o f the Moosev a l e Formation on the S u s t u t p r o p e r t y . in d r i l l  However, s p o r a d i c s u l p h i d e s are  c o r e to the bottoms o f DDH's 88 and 110,. t h a t  range o f 600 m.  present  is over a v e r t i c a l  Most copper and s u l p h i d e m i n e r a l i z a t i o n i s c o n c e n t r a t e d i n  e x t e n s i v e t a b u l a r zones which are roughly p a r a l l e l  to bedding.  W i t h i n these  86 zones a crude v e r t i c a l  zonation of m e t a l l i c minerals  is present,  from n a t i v e  copper c o r e s , outward through c h a l c o c i t e , b o r n i t e , c h a l c o p y r i t e , and to p y r i t e envelopes.  T h i s z o n a t i o n i s not found t o be p e r f e c t l y s y m m e t r i c a l  in a l l p l a c e s and l o c a l l y i s amounts o f s u l p h i d e s  finally  incomplete.  In the 9 8 . p o l i s h e d s e c t i o n s  studied,  p l u s n a t i v e copper ranged from n i l t o 12 volume p e r c e n t  of the s e c t i o n s and averaged about 5 p e r c e n t . Copper m i n e r a l s a r e found in l o c a l l e t s which p i n c h and s w e l l  irregularly.  swarms o f t h i n , s t e e p l y d i p p i n g v e i n Q u a r t z , c a r b o n a t e , e p i d o t e , and  p r e h n i t e are i n t e r g r o w n w i t h the o r e m i n e r a l s  i n these v e i n s .  l a r zones and v e i n l e t s merge; elsewhere v e i n l e t s c u t t a b u l a r  In p l a c e s  tabu-  zones.  An a s p e c t o f s u r f a c e o c c u r r e n c e s o f . c o p p e r m i n e r a l i z a t i o n i s the presence o f an o r a n g e - r e d ,  so-called,  1  copper-moss 'which 1  h i g h e r than background copper c o n t e n t . algae f a m i l y .  grows on rocks w i t h have a-  A c t u a l l y the  'moss'  i s o f the green  It has been i d e n t i f i e d as T r e n t o p o h l i a i o l i t h u s  (L.).  This  a l g a e i s common t h r o u g h the w o r l d in areas o f h i g h a l t i t u d e s and l a t i t u d e s , but has o n l y been r e p o r t e d i n two areas Copper  (Harper,  1973)-  This  i n B r i t i s h C o l u m b i a , o t h e r than  ' m o s s ' does not grow on a r e a s o f h i g h  Sustut  copper  c o n c e n t r a t i o n , say g r e a t e r than 1 p e r c e n t , p r o b a b l y due to t o x i c i t y o f  large  amounts of c o p p e r .  finding  minor copper v a l u e s .  Wherever t h i s  'moss'  i s seen one can be assured o f  F r a c t u r e s and j o i n t s which c u t through o r e m i n e r a l  zones  and which may have caused small s c a l e m i g r a t i o n o r l e a c h i n g o f minor amounts o f copper g e n e r a l l y have the best growths o f the  5.2  'moss . 1  Ore Lenses  The S u s t u t  Copper d e p o s i t was d i s c o v e r e d as a r e s u l t o f o b s e r v a t i o n o f  m a l a c h i t e s t a i n i n g on c l i f f s  surrounding  the p r o p e r t y .  Closer  examination  r e v e a l e d t h a t f i n e - g r a i n e d ore m i n e r a l s were d i s s e m i n a t e d through the f i n e f r a c t i o n s o f the v o l c a n i c l a s t i c c o n g l o m e r a t e s .  These ore d i s s e m i n a t i o n s  were  r e s t r i c t e d to l i t h o - f a c i e s i n t e r b e d s w i t h i n the host v o l c a n i c l a s t i c r o c k s ,  87 such t h a t ore m i n e r a l i z a t i o n a c t u a l l y o c c u r s as i r r e g u l a r a r e a l e x t e n t s and p a r a l l e l b e d d i n g . s e r i e s o f these  lenses.  i t i o n of p h y s i c a l  The l e n s e s a r e o f  The d e p o s i t c o n s i s t s o f a  Use o f the computer based c o r e logs l e d to the d e f i n -  c h a r a c t e r i s t i c s o f the c o n g l o m e r a t e s which were c o n d u c i v e  to o r e m i n e r a l i z a t i o n . host  lenses.  Chemical a n a l y s e s  o f o r e l e n s e s and t h e i r e n v e l o p i n g  rocks shows a very sharp c u t - o f f i n copper v a l u e s , g r a d i n g outwards  the l e n s e s .  Gangue m i n e r a l s are e x t e n s i v e l y  i n t e r g r o w n w i t h the o r e m i n e r a l s  and the gangue i s o f p r e h n i t e - p u m p e l l y i t e f a c i e s  grade.  In the f o l l o w i n g d e s c r i p t i o n o f o r e m i n e r a l o c c u r r e n c e , areas d e p o s i t a r e r e f e r r e d t o by t h e i r sample number  (eg. W104).  i n the  The sample l o c a -  t i o n s are on the p r o p e r t y geology map ( i n the pocket a t the end o f t h i s 5.2.1  from  thesis).  Outcrop Appearance o f Ore Copper o c c u r r e n c e s were f i r s t d i s c o v e r e d on the S u s t u t  P r o p e r t y when  m a l a c h i t e s t a i n i n g was o b s e r v e d a l o n g the upper p o r t i o n s o f the c l i f f s on the e a s t e r n edge o f t h e d e p o s i t see f r o n t p i e c e ) .  ( i e . the c l i f f s  p a r a l l e i i n g the S u s t u t  River V a l l e y -  The s t a i n i n g extended o v e r a v e r t i c a l t h i c k n e s s o f about 6 m,  and was seen t o c l o s e l y c o r r e s p o n d to the bedding p l a n e . c h i t e s t a i n can be t r a c e d a l o n g the c l i f f s e r n end o f the South Zone,  The zone o f m a l a -  s p o r a d i c a l l y from near the s o u t h -  i n t o the c i r q u e to the n o r t h where i t ends.  Other  bands o f m a l a c h i t e appear a l o n g the n o r t h e r n edge o f the c i r q u e , the e a s t e r n c l i f f s o f the North Zone and a l s o on the North  Cliffs.  F o l l o w - u p g e o l o g i c a l e x a m i n a t i o n showed the m a l a c h i t e to be a s u r f a c e o x i d a t i o n e f f e c t d e v e l o p e d on copper s u l p h i d e - r i c h t a b u l a r l a y e r s .  These  l a y e r s a l s o appeared to be up to 6 m t h i c k .  along  cliff  A l t h o u g h best o b s e r v e d  f a c e s , some c o p p e r - r i c h l a y e r s are seen to crop o u t .  It was  first  thought t h a t a l l t h e s e l a y e r s d e f i n e d one s t r a t i f o r m , o r even s t r a t a b o u n d , zone through several  the p r o p e r t y .  However subsequent  work has shown t h a t t h e r e are  d i s t i n c t , t a b u l a r ore lenses which p a r a l l e l b e d d i n g .  have d i f f e r i n g l a t e r a l  and v e r t i c a l  dimensions.  These  lenses  Where seen i n outcrop, s u l p h i d e s grained  (on the o r d e r o f 0.1  varies  from 0.01  Amount o f s u l p h i d e  to 15 p e r c e n t .  m a t r i c e s , but where i n t e n s e ,  is p r e s e n t  is d i s s e m i n a t e d  (based on v i s u a l  estimain Chalco-  seen in the o r e l e n s e s .  are not r i c h and g e n e r a l l y are e i t h e r s e p a r a t e  In the r i c h e s t l e n s e s  volcaniclastic  in volcanic c l a s t s a l s o .  i n p l a c e s w i t h the b o r n i t e .  iated with c h a l c o c i t e .  through  fine  M i n e r a l i z a t i o n i s m a i n l y seen  c i t e w i t h b o r n i t e are the dominant s u l p h i d e s pyrite  are p r e s e n t as  to 1 mm) d i s s e m i n a t i o n s  sandstones and c o n g l o m e r a t e s . tions)  in the lenses  Chalco-  N a t i v e copper  disseminations  from s u l p h i d e s  o r are a s s o c -  P y r i t e a l s o commonly o c c u r s w i t h o u t o t h e r  sulphides.  s p e c u l a r h e m a t i t e o f t e n imparts a r e d d i s h t i n g e to the  mi n e r a 1 i zed a r e a . On the n o r t h w e s t e r n edge o f the North C l i f f s , extend l a t e r a l l y is along study for  f o r . o v e r 360 m.  This  lens, approximately  the 6575 t o 6600 f t . e l e v a t i o n .  this  lens  in d e t a i l  but  an ore lens  its extent  1.5  is seen  to  to 3 m t h i c k ,  U n f o r t u n a t e l y the author d i d not i n t o the North Zone appears  limited,  i t i s not seen t o crop out w i t h i n the North Zone even at l i k e l y  elevations  as e x t r a p o l a t e d from known o c c u r r e n c e s . A set o f cirque.  l e n s e s crop out at the head and on the North Zone s i d e o f  One such lens o c c u r s  r i g h t a t the d y k e ' s  in c o n t a c t w i t h the e a s t e r n s i d e o f the dyke  c o n t a c t w i t h the f a u l t - d e f i n e d c i r q u e (sample W104  Here, 1:0 to 15 p e r c e n t , f i n e (< 0.5 mm) c h a l c o c i t e and b o r n i t e g r a i n s i n t e r g r a n u l a r spaces  i n a medium g r a i n e d s a n d s t o n e .  w i t h a l a r g e s i z e f r a c t i o n ) both above and below.  the host  rock.  The l a t e r a l  s i d e o f the dyke-but  These conglomerates i n 1.5 m upwards  e x t e n t i s seen to be k by 3 m, but is  l a r g e r as the bed i s obscured  in d e b r i s .  This  fill  T h i s p a r t i c u l a r sandy  i s on the o r d e r o f 0.3 rn t h i c k and grades i n t o sandy conglomerates  s u l p h i d e - r i c h a l s o , but v i s i b l e s u l p h i d e - d i e s out  site).  A s s o c i a t e d w i t h the s u l -  phides a r e abundant e p i d o t e and s p e c u l a r h a m a t i t e . unit  the  lens  (ie. are  through probably  is not seen on the o t h e r  t r a c e amounts o f n a t i v e copper and c h a l c o c i t e a r e  visi-  89 ble  i n m a t r i c e s o f conglomerates  bility  here.  to m i n e r a l i z i n g s o l u t i o n s ,  Near W112 irregularly  a l o n g the head o f the c i r q u e .  f r a c t u r e s and  the  lens.  The  o f minor d i s s e m i n a t e d  lens i t s e l f  irregularity  copper from  the  c o n s i s t s of c h a l c o c i t e and  appears is  quartz pores.  to extend  Sulphide content  'copper  T h i s can be  Thickness  lens at W19,  minerals occur  i n these  moss  This  indi-  indicates  lens o c c u r r e d a f t e r  fault-  b o r n i t e s c a t t e r e d through (0.1  in small  i s l e s s than 0 . 5  to 1 mm  percent.  in  T h i s lens  is variable,  but  i s never  greater  than  moss , o c c u r 1  m a l a c h i t e w i t h minor amounts o f a z u r i t e ,  in a zone which  lapping matrices  layers. took  malachite  bilized  from  and  can be seen  up d e f o r m a t i o n a l  strain  to occur  in t h i s  in two  the ore  s i t e o f sample W32.  lens below (j_e_. sample WIOA ore  rock.  There  that a t sample area w l 9 -  richer  the  may  over-  silt-sized  sample  lens crops out  1 m t h i c k and  have been remo-  l o c a t i o n ) on  ( f i g . 37)  to  m a l a c h i t e zone above the l e n s  T h i s lens i s connected  at  c o n s i s t s o f 5 to  b o r n i t e i n a coarse sandstone  i s a sheared  m i n e r a l i z e d gangue-fi1 led v e i n s .  partly  lens) d u r i n g the s h e a r i n g .  l e n s (near the W112  T h i s lens i s about  f i n e - g r a i n e d c h a l c o c i t e and  interval  r a t h e r than the coarse f r a c t i o n . c l a s t s .  i s present because small amounts o f copper  the n o r t h f a c e o f the c i r q u e , another  conglomeratic  but  These l a y e r s appear t o be shear zones wherein  Twelve t o f i f t e e n m above t h i s  percent  10 m,  and  ( f i g . 3&) .  i s e x t e n s i v e l y sheared  t r a c e d along the rock f a c e f o r about  is not c o n f i n e d to a s i n g l e bed  The  fault-  m. Above t h i s  some  to  s p o r a d i c a l l y a l o n g the n o r t h e r n f a c e o f the c i r q u e where i t  t r u n c a t e d by a f a u l t .  1.5  i s due  sulphides.  the m a t r i x o f a coarse s a n d s t o n e - f i n e conglomerate diameter)  extends  i s h e a v i l y overgrown by copper  that some minor r e m o b i 1 i z a t i o n o f copper ing.  The  lens o c c u r s which  Minor amounts o f copper  the whole b l u f f here  the presence  i t s relative.impermea-  the dyke i s not v i s i b l y m i n e r a l i z e d h e r e .  ( i e . the sample l o c a t i o n ) an ore  ing which has o f f s e t  cating  As a r e s u l t o f  to the W112  the  10  fine like  lens below by  90  Figure is  just  1  Figure is  lens is  1  a t W32  are a series  is  Malachite  above  stain  a significant  on s h e a r ore  zone.  This  zone  lens.  _  lens  the N o r t h  probably  lens.  •  Ore  37:  towards  36:  just  locations Zone w h i c h visible,  a continuation of of s u l p h i d e - r i c h  The v e r t i c a l  on n o r t h e r n edge o f  relief  is  as  cirque.  This  view  is  in the background.  The m a j o r  ore  is  a s m a l l e r one b e l o w  (ie.  lens  theW1l2 veins. about  lens). Veins  55  rn..  Between  also  this  these  two  lenses  occur below  the  W112  91 At s e v e r a l p l a c e s i n the North Zone ore l e n s e s a r e found a t ground l e v e l (or a t l e a s t s p o r a d i c o c c u r r e n c e s o f s u l p h i d e s are found c r o p p i n g out zone).  Near sample a r e a W92,  in t h i s  a r u s t y w e a t h e r i n g conglomerate i s v i s i b l e i n  w h i c h small r e l i c t g r a i n s o f p y r i t e and/or c h a l c o p y r i t e were found i n gaps the m a t r i x ( f i g . 3 8 ).  At V/98,  in  ( i e . sample l o c a t i o n ) d i s s e m i n a t e d n a t i v e  copper and r a r e c h a l c o c i t e a r e i n s a n d y - c o n g l o m e r a t i c h o r i z o n s near the dyke. Minor copper v a l u e s and copper moss are found in v a r i o u s a r e a s o f the North Zone t h a t are cut by s t r o n g j o i n t i n g and/or f r a c t u r i n g . a t W95  the w a l l  rock to a c a r b o n a t e - q u a r t z c o a t e d f r a c t u r e zone c o n t a i n s  c h a l c o c i t e and b o r n i t e i n q u a r t z - f i l l e d p a t c h e s .  These q u a r t z patches form  cement to the somewhat open framework o f the host c o n g l o m e r a t e . W33  For example,  At W100 and  j o i n t i n g i s f a i r l y s t r o n g , here t r a c e amounts o f c h a l c o c i t e w i t h m a l a -  c h i t e a n d copper moss o c c u r in the host rock where j o i n t i n g i s  strongest.  Near (sample a r e a s ) W10, W11, and W12, on the south w a l l o f the c i r q u e , two d i s t i n c t ore l e n s e s o c c u r . edge o f the c l i f f by DDH 104. b o u n d a r i e s at l a t e r a l  The lower lens This  extremities.  lens Its  i s a p p r o x i m a t e l y 21 m below the  i s about 10 m i n l e n g t h and has thickness  i s about 1.5  t o 2 m.  sharp The  h o r i z o n c o n s i s t s o f c h a l c o c i t e and b o r n i t e w i t h minor amounts o f c h a l c o p y r i t e and r a r e p y r i t e d i s s e m i n a t e d through g a n g u e - f i 1 1 e d p o r t i o n s o f m a t r i c e s f i n e f r a c t i o n s ) and in c l a s t s  in c o n g l o m e r a t e s .  (or  The l a y e r has an open frame-  work. The upper c o p p e r - r i c h l e n s i s about 6 m above the f i r s t . l e n s has a l a t e r a l near a f a u l t .  e x t e n t o f 120 m a l o n g the c l i f f  face before  This  copper  dissappearing  M a l a c h i t e i s v e r y s t r o n g l y developed on t h i s upper lens and  makes the lens v i s i b l e .  Between both l e n s e s h e r e , a b a r r e n p e b b l y conglomer-  a t e o c c u r s , which appears to have a much l e s s open framework. Another h o r i z o n , w i t h a 6 m t h i c k n e s s and a 30 m l e n g t h , o c c u r s on the cliff  a t the s o u t h e a s t e r n edge o f the c i r q u e .  oped m a l a c h i t e s t a i n .  T h i s h o r i z o n has a w e l l  devel-  32  F i g u r e 38: pyrite,  as  Outcrop  view of  shown by  brownish  intraclast  tape  i s 2 cm  Sulphide mineralization long.  the tape where  An  offshoot of  it visibly  occurs  below t h i s where  rock.  This proves  disrupts  The  sulphide weathering,  i n gaps b e t w e e n t h e c o a r s e f r a c t i o n  F i g u r e 39:  pyrite.  occurs  clasts.  brecciating  host  rock.  the s u l p h i d e zone o c c u r s bedding.  i t wraps around  The  a coarse  s u l p h i d e i n t r o d u c t i o n was  not  The just  white below  main s u l p h i d e zone sandy  fragment  syngenetic.  of  host  93 The l e n s w i t h the l a r g e s t e x t e n t , o b s e r v e d by the w r i t e r , i s seen t o c r o p out i n the c l i f f s This  a l o n g the e a s t e r n s i d e o f the South Zone ( f r o n t i s p i e c e ) .  l e n s , which p a r a l l e l s b e d d i n g , e x t e n d s from below DDH 109 more than 600 m •  j u s t to the e a s t o f DDH 39. 1 to 5 m.  This  t a b u l a r zone has a v a r i a b l e t h i c k n e s s  A pronounced e p i d o t e a l t e r a t i o n i s e v i d e n t w i t h i n t h i s  Samples W 5 7 the South Zone. disappears  t o W60 and W64 a r e a l l from a s m a l l This  lens  l e n s which o c c u r s w i t h i n  The j o i n t i n g i s p a r a l l e l  The h o s t rocks c o n s i s t o f  f i n e conglomerates w i t h f i n e t o medium-grained sand i n t e r b e d s . b o r n i t e and c h a l c o c i t e , f i l l  tite.  to b e d d i n g .  i n a p o r t i o n o f the h o s t v o l c a n i c l a s t i c rocks which have e x t e n -  s i v e and r e p e t a t i v e s m a l l s c a l e graded b e d d i n g .  frameworks.  lens.  i s t r u n c a t e d by a d i p s l i p f a u l t a t one end and  i n a j o i n t e d a r e a a t the o t h e r .  The l e n s o c c u r s  from  The s u l p h i d e s ,  i n t e r s t i c e s i n those r o c k s which have more open  The s u l p h i d e s a r e i n t e r g r o w n e x t e n s i v e l y w i t h s p e c u l a r i t i c hema-  The o r e m i n e r a l s a r e u s u a l l y c o n c e n t r a t e d i n c o a r s e r sandy p o r t i o n s o f  the graded beds. E v i d e n c e f o r p o s t - c o n s o l i d a t i o n i n t r o d u c t i o n o f the s u l p h i d e s  is well  e x i b i t e d by one sample (W57) from t h i s a r e a ( f i g . 3 9 ) . In t h i s sample ganguef i l l i n g s u l p h i d e patches appear t o i n t r u d e i n t o the bedding p l a c e o f the host rock and i n d o i n g so d i s r u p t and c r o s s - c u t the b e d d i n g , and b r e c c i a t e the host rock i n t o f r a g m e n t s . 5.2.2  Appearance o f Ore Lenses i n D r i l l Study o f the d r i l l  gularly,  Core  c o r e i n d i c a t e s t h a t the o r e l e n s e s a r e p r e s e n t ,  to near the base o f the M o o s e v a l e ' s  upper member.  irre-  The l a r g e s t and  most c o p p e r - r i c h h o r i z o n s are i n the upper p o r t i o n s o f the d e p o s i t , w h i l e the lower h o r i z o n s are s m a l l e r i n volume and are d o m i n a n t l y cha1 c o p y r i t i c and/or p y r i t i c i n lower a r e a s .  in composition.  However, some minor c h a l c o c i t e zones a r e found  N a t i v e copper and g r e e n o c k i t e are found o n l y  h o r i z o n s near the t o p .  i n the l a r g e r " "  3k The h o r i z o n  w i t h the l a r g e s t v e r t i c a l  a h o r i z o n extends hole.  Large  f o r o v e r 12 m, from 5 t o 2k  c  i s found in DDH 2 where  f t from the top o f the  drill  l e n s e s a r e a l s o seen i n DDH s 39, 8 8 , 1 10, 6, 5 3 , 9 6 , 5 k ,  10, where  1  the h o r i z o n s a r e k5, different  expression  lenses  39, 37, 36, 3 0 , 30, 2 8 , 27 m t h i c k r e s p e c t i v e l y .  i n t e r s e c t e d in a s i n g l e d r i l l  i n t e r v a l s o f 1.5 t o 6m.  Commonly  h o l e a r e s e p a r a t e d by b a r r e n  A l s o , w i t h i n some o f the l e n s e s ,  r i c h zones o f up to 2  p e r c e n t v i s i b l e s u l p h i d e are s e p a r a t e d by l a r g e a r e a s w h e r e i n the amount o f v i s i b l e s u l p h i d e c o n c e n t r a t i o n can be as l i t t l e as a t r a c e in a f i v e f o o t val.  Thus some o f the l a r g e r lenses can a c t u a l l y be s u b d i v i d e d  inter-  into smaller  ones on the b a s i s o f amount o f ore m i n e r a l i z a t i o n . All  o f the d r i l l  h o l e s s t u d i e d c o n t a i n e d s i g n i f i c a n t amount o f copper  m i n e r a l i z a t i o n e x c e p t DDH's 25 and 132. in p y r i t e though. considerably, the d r i l l  P o s i t i o n o f lenses  These  latter  two h o l e s are f a i r l y  in r e l a t i o n to top o f d r i l l  holes  i n d i c a t i n g o f course d i f f e r i n g t o p o g r a p h i c p o s i t i o n s  from w h i c h  through the ore l e n s e s a r e much more e a s i l y s t u d i e d i n  core than i n o u t c r o p .  A good example o f how one o f the l e n s e s o c c u r s  in DDH 6.  is present u n t i l  No s u l p h i d e  where t r a c e c h a l c o c i t e o c c u r s  host  i n some q u a r t z - f i l l e d pores  k2 m below the s u r f a c e , the s u l p h i d e 0.1  per  pores, gradually  in g a n g u e - f i 1 1 e d  more open and f i l l e d  w i t h gangue w i t h a r e s u l t a n t  (6B3: from 50 rn below the s u r f a c e )  (analysis  lens  drill  found hole  conglom-  through  the  is encountered.  to 0.5 p e r c e n t c h a l c o c i t e and n a t i v e c o p the m a t r i x framework becomes i n c r e a s e in amount o f c h a l c o -  c i t e and n a t i v e copper d i s s e m i n a t e d through the m a t r i x . ple analysed  in the host  i r r e g u l a r l y downwards  At the s t a r t o f t h i s zone ( l e n s ) are present  is  18 m below the c o l l a r o f the d r i l l  C h a l c o c i t e , i n these p o r e s , o c c u r s  rock s e c t i o n u n t i l  sequence  varied  h o l e s were s t a r t e d .  Cross-sections  erate.  rich  The h i g h e s t grade  came from p a r t o f t h i s  proved copper grades o f about 10 p e r c e n t in t h i s  lens  sample).  At t h i s p o i n t the conglomerate e x h i b i t s the most open framework seen in the i n t e r v a l , and i n t e n s e e p i d o t e w i t h c a r b o n a t e and q u a r t z , f i l l  the  sam-  95 matrices.  J u s t 1 m below the l o c a t i o n o f sample 6B3, the  framework o f the m a t r i x becomes c l o s e d and c h a l c o c i t e i s p r e s e n t to o n l y 0.05 to 0.1 p e r c e n t .  Through to the end o f the zone, 30 m below, the c h a l c o -  c i t e and n a t i v e copper c o n t e n t s vary from t r a c e t o 2 p e r c e n t , where the h i g h e s t grades c o r r e l a t e w i t h rocks having an open r a t h e r than c l o s e d framework. Thus, o r e m i n e r a l s . a r e r i c h e s t where the host conglomerate  has the g r e a t e s t  p r e - m i n e r a l z a t i o n p e r m e a b i l i t y as e x h i b i t e d now m a i n l y by the presence o f intersertal  cement.-  Four c r o s s - s e c t i o n s in d e t a i l  were c o n s t r u c t e d t o i n c l u d e the d r i l l  (see c r o s s - s e c t i o n s  attached).  holes  studied  The two s e c t i o n s from the North  Zone (Ls.DDH's 54-110-17 52 and 44-53 52: see a t t a c h e d p r o p e r t y geology map _  -  where t h e s e s e c t i o n s a r e p l o t t e d as B-B' and A - A m i n e r a l i z a t i o n here appears t o be a s i n g l e ,  1  r e s p e c t i v e l y ) show t h a t the  s t r a t i f o r m lens.  However most o f  the h o l e s a r e s h o r t and do not g i v e a d e t a i l e d view o f lower s t r a t a . pyritic  l e n s o c c u r s below the main lens  seperated ore lenses  t o i t s bottom.  i n DDH 44.  A l s o DDH 110 shows s e v e r a l  DDH 17 appears  t o c u t two l e n s e s ; the  major c h a 1 c o c i t e - n a t i v e - c o p p e r - b o r n i t e l e n s and a l s o a 12 m t h i c k lens.,  A small  pyritic  4.5 m below the major one. S e c t i o n DDH 88-2-105-5-112 ( i n the South Zone - s e c t i o n C - C on the  geology map) shows t h a t t h e r e i s a broad s u l p h i d e swath c u t t i n g the upper p o r t i o n s o f the d e p o s i t . form and d o e s n ' t  However t h i s s u l p h i d e zone i s r a t h e r i r r e g u l a r i n  f o l l o w bedding a t DDH s 105, 6, 112. 1  r a t h e r l a r g e s u l p h i d e lenses 116-10-39-96 ( a l s o several  through  i t s length.  DDH 88 a l s o shows some  The l a s t s e c t i o n DDH 132-13"  i n the South Zone - s e c t i o n D-D' on the geology map) r e v e a l s  d i s t i n c t horizons  i n the top u n i t s .  For i n s t a n c e DDH 13 shows t h r e e  d i s t i n c t h o r i z o n s w i t h i n i t s l e n g t h , as does DDH 10. Thus the o r e m i n e r a l i z a t i o n o c c u r s parallel  i n s e p a r a t e l e n s o i d forms which  b e d d i n g , but which a r e i r r e g u l a r i n l a t e r a l  a p p e a r i n g and d i s a p p e a r i n g w i t h suddeness.  and v e r t i c a l  extent,  The l e n s e s a r e a l s o s e p a r a t e d by  96 barren 5.2.3  rock. L i t h i c V a r i a b l e s and t h e i r R e l a t i o n to M i n e r a l i z a t i o n  Computer programs ascertain  were designed  f o r use w i t h the core log f i l e s ,  i f any, o r a l l , o r the v a r i a b l e s  i n t e r v a l s f o r the host c o n g l o m e r a t e s , These programs  mainly  consistently  to  recorded on f i v e  c o r r e l a t e d with ore mineral  foot  occurrence.  i n v o l v e d the p r i n t i n g out o f m a t r i c e s where the o r d i n a t e  v a l u e s were the d i f f e r e n t codes f o r the v a r i a b l e i n q u e s t i o n and the a b s i c c a was d i v i d e d i n t o d i f f e r e n t v i s u a l (recorded  i n the l o g g i n g ) .  were e x h i b i t e d .  percentage values of a p a r t i c u l a r ore mineral  In e a c h amount o f m i n e r a l \^s_. a d e f i n e d v a r i a b l e (  These v a l u e s o f number o f v a r i a b l e s w i t h ore m i n e r a l i z a t i o n  were then compared as a p r o p o r t i o n o f t h a t v a r i a b l e m i n e r a l i z e d number o f o b s e r v a t i o n s T h i s method o f s t u d y i n g  o f the v a r i a b l e both m i n e r a l i z e d and the logs l e d t o some i n t e r e s t i n g  vs.  the t o t a l  unminera1ized.  interpretations.  F i g . 40 i s a graph o f the l i t h o l o g i c u n i t s , seen on the p r o p e r t y , the p r o p o r t i o n o f o b s e r v a t i o n s chalcocite.  vs.  o f each l i t h o l o g i c type which c o n t a i n e d  (Polished section studies  have shown t h a t b o r n i t e  is  visible  intimately  i n t e r g r o w n w i t h c h a l c o c i t e - thus where c h a l c o c i t e was v i s i b l y o b s e r v e d , i t e can be assumed to be p r e s e n t a l s o ) .  It  is  r e a d i l y seen from f i g . 40 t h a t  the rock type d o m i n a n t l y m i n e r a l i z e d w i t h c h a l c o c i t e i s AGGR, however a l s o obvious  it  t h a t conglomerates w i t h m a i n l y green c o l o u r a t i o n s are more  m i n e r a l i z e d than o t h e r s . T h i s c o n c e n t r a t i o n o f m e t a l l i c m i n e r a l s conglomerates  born-  in  is  highly  green  i s shown even b e t t e r by p y r i t e ( f i g . kV. where o v e r 50 p e r c e n t  o f the o b s e r v a t i o n s  o f rock type AGGG c o n t a i n e d p y r i t e .  F i g . 42 shows percentage m a t r i x v a l u e s  (of the conglomerates)  t i o n o f each which c o n t a i n s v i s i b l e c h a l c o c i t e . in conglomerates  w i t h 50 to 70 p e r c e n t m a t r i x .  vs_.  C h a l c o c i t e thus o c c u r s F i g . 4.3' has  propormainly  texture values  p r o p o r t i o n w i t h c h a l c o c i t e , c h a l c o c i t e i s found very d o m i n a n t l y  in  conglomer-  a t e s w i t h a t e x t u r e o f 25 t o 50 p e r c e n t l a r g e f r a c t i o n in a c l o s e d m a t r i x , secondarily  vs.  and  i n conglomerates w i t h 25 t o 50 p e r c e n t l a r g e f r a c t i o n i n an open  Yajmojrtt-i  w  r-  <-£  O  o T  o o  o OL  •20 10  0 I—V  r J  12,  9* Cv  XP  6"^  '^0 L  I  T  H  0  L  0  63 1  F i g u r e 'lO:. P r o p o r t i o n s o f each l i t h o l o g i c type m i n e r a l i z e d w i t h c h a l c o c i t e . T h i s i s a d r a u g h t e d v e r s i o n o f a c o m p u t e r - r e t r i e v e d t a b u l a t i o n . V e r t i c a l w i d t h o f bar is the e r r o r s o f the e s t i m a t e (x ± s The p r o p o r t i o n s a r e based on c o m p a r i s o n o f a l l o b s e r v a t i o n s o f e a c h l i t h o l o g i c t y p e .  if}  a,.  I U  - 3 0  O  ^  I0h JL  "ft  61 I  ——^>  Figure 41: P r o p o r t i o n s o f each l i t h o l o g i c type m i n e r a l i z e d w i t h p y r i t e . e r r o r o f the e s t i m a t e (x ± s j . (Draughted v e r s i o n o f a c o m p u t e r - r e t r i e v e d  V e r t i c a l w i d t h o f bar tabulation).  i s the  •3 Oh 20  0  10 20 30 40 50 60 PERCENT.  70  80  90  MATRIX a^mnpm^juiii 'nj.nujiaj.wJ no  F i g u r e 42: P r o p o r t i o n s o f each p e r c e n t m a t r i x v a l u e ( i n c o n g l o m e r a t e s ) m i n e r a l i z e d w i t h c h a l c o c i t e . V e r t i c a l w i d t h of. bar i s the e r r o r s o f the e s t i m a t e (x ± s j . (Draughted v e r s i o n o f a c o m p u t e r - r e t r i e v e d tabulat ionj. -  vx>  Closed  Open  Framework  1.0  n-1  I  Framework  . 100%  (X3 <D  CL  E  (0  CO  CD C  i_  0.2  (0 (1)  DQ  I U CJ  0.1.1 CL O  Cu  1  10-25  1  25-50  1  50-75  % Figure  h3:  Proportions  of different  Large  f r a m e w o r k c a n be n e g l e c t e d  was made l i e . n = l ) .  —  r  [ —  -  <10  10-25  I  i  25-50  50-75  Fraction  texture groupings mineralized  w i d t h o f b a r i s the e r r o r s o f the estimate in an open  1  >75  (x ± s ) .  chalcocite.  T h e t e x t u r e o f <. 10 p e r c e n t  as i n s i g n i f i c a n t  (Draughted v e r s i o n o f computer  with  as o n l y  one o b s e r v a t i o n  tabulation).  Vertical  large of this  fraction texture  IUI  mat r i x . Comparison o f s o r t i n g  values  vs.  proportion containing chalcocite ( f i g . 44)  shows an i n t e r e s t i n g c o r r e l a t i o n w h e r e i n m o d e r a t e l y s o r t e d conglomerates sorting is  v a l u e s o f 4 and 5 ) a r e d o m i n a n t l y m i n e r a l i z e d .  i m p o r t a n t as  it  indicates  amount o f m i n e r a l i z a t i o n .  thus  as  Conglomerates  clastic  incoming f l u i d s  rocks,  the g r e a t e r s h o u l d be the  chalcocite  is p l o t t e d vs.  (fig. 45), it  is  ( i e . grain s i z e R in f i g . 4 5 ) . 20 percent of observations  and c o a r s e  f r a c t i o n sizes  of small  sorting  in  nature  coarse-grained  porosity. p r o p o r t i o n o f samples  types  contain  had g r e a t e r  L,' M, N,  to f i n e sand  G r e a t e r than 10 p e r c e n t m i n e r a l i z e d samples were found i n g r a i n  very'coarse sizes;  <,  sand, or small  than  in f i g . 4 5 ) .  l a r g e r , c o n t a i n the most  K, Q, W, X and Y (from f i g . 4 5 ) w h i c h had s i l t  for  i n a f i n e sand m a t r i x  also  g r e a t e r than o r equal pebbles or  that  most f a v o u r a b l e  large pebble s i z e  mineralized (ie. grain sizes  that f i n e f r a c t i o n sizes  B,  i n medium to  Four o t h e r s i z e  is obvious  characteristics  are very angular  found t h a t the c o n g l o m e r a t e s  m i n e r a l i z a t i o n have a l a r g e f r a c t i o n o f  r e f l e c t s the  than those w i t h o t h e r  grains  the u n i f o r m i t y o f g r a i n s i z e  When the g r a i n s i z e  cite.  w i t h moderate s o r t i n g  the f i n e f r a c t i o n <Je_. m a t r i x ]  the g r e a t e r  observation  t h a t p o r o s i t y o f the c o n g l o m e r a t e s  s h o u l d be more porous towards values,  This  (ie.  size, chalcosizes;  o r f i n e sand f i n e f r a c t i o n s  p eb b le to c o b b l e s i z e 1 a r g e f r a g m e n t s .  It  to  Grain  V, Z, T, E, H, C ( f i g . 4 5 ) were shown t o be t o t a l l y u n m i n e r a 1 i z e d  wi t h c h a l c o c i t e . 5.2.4  Optimum Ore It has  istics  Horizon  been shown t h a t  are more l i k e l y  istics. and thus  rocks w i t h c e r t a i n d i s t i n c t i v e phys-ical  to be m i n e r a l i z e d than a r e rocks w i t h o t h e r  But do t h e s e s p e c i f i e d v a r i a b l e s o c c u r t o g e t h e r define horizons  more h i g h l y lithologic  o r interbeds  m i n e r a l i z e d than any o t h e r s units  present)?  character-  i n the h o s t  i n the v o l c a n i c l a s t i c p i l e ( i e . a r e t h e r e optimumly  character-  that  rocks, are  mineralized  ~  —  FRO?'-'- CC. BEARING S A M P L E S  io  re  c • re -« - i re  - ro o o o  -\  0  -c-  ui  ..  O -\  •  O  rr  r r -a re o -i Q  IT  01  rr  O  rr  O  —  — rj 5 i/i cu  re .— in  ro  -I-I  XI o  -1  .  H- rr vi 3 •~*{r,  OJ  <  -—. 0) O  — '  c a> re c w ~ 3 -1  rr —•  re C <  -J CD -\ OJ  re  —  - i  —  Ul  N  —  re  o o o o c  CL  z  —  o rr  OJ o o o  -4b  a re cr • c OJ  <:  rr (D — -I O rr D — O  •  QJ  z CL rr  o  tr  OJ -i  ZOl  o  103  FINER  FRACTION  CLAY  fine 1/15  8 OC LU  _J  -  £  o  DQ  co  CM  CO CQ  o o  <  Tt  CC  CD  AC  LU  re  _j  ~~  1/4  1 mm  2  0 phi  4  o  W  X  0.0  .13  .11  .07  0.0  n =2  n = 55  n =143  n=15  n =1  P  Q  .14 K  re  .10  .12  <n  n = 21  n=121  E  F  E  <  V  J _  Z>  --V=Yoo~  n =278  CL  DC LU CO  n =2  n = 39  LU  CM I  LU _J  z  < cc CC  V. COARS &SMALLE  LU  coarse  0.0  .03  CQ  LL  O u  I  CQ  cc  cc  CD  rge  o  l-  1  1  2  z O  a  to co  LU  —  med.  <  d  LU N  SIZE  S A ND  SILT  1 /256  GRAIN  Y  Ills  S  "n""=699  Z  T  .09  0.0  n =67  n= 6  ill SHI =  G  n=~52~  :  H  0.0  .05  .06  0.0  n = 17  n=37  n = 31  n =9  CM  B :  C  .14  o.o  n =7  n =  8  F i g u r e 4 5 : G r a i n s i z e c l a s s i f i c a t i o n c h a r t w i t h p r o p o r t i o n o f each g r a i n s i z e t y p e m i n e r a l i z e d w i t h c h a l c o c i t e . T h i s c h a r t i s m o d i f i e d from B l a n c h e t and Godwin (1972) Codes f o r each g r a i n s i z e c l a s s i f i c a t i o n o c c u r a t the top o f each b l o c k i n t h i s d i a gram. The n o . ' o f o b s e r v a t i o n s (_i_e_. n=) o f each c l a s s a r e r e p r e s e n t e d at t h e b o t t o m o f the b l o c k . The n o . ' s i n t h e c e n t r e o f the b l o c k s r e p r e s e n t the p r o p o r t i o n o f each c l a s s m i n e r a l i z e d w i t h c h a l c o c i t e . S t r o n g c h a l c o c i t e b l o c k s a r e shaded.  104 In o r d e r  to a s c e r t a i n t h i s ,  s i z e and p e r c e n t a g e m a t r i x alized  the d i f f e r e n t v a r i a b l e s  (fine fraction)  w i t h the h i g h e s t  i n the rock type AGGR were p l o t t e d a g a i n s t  three matrices  thus d e f i n e d  ( i e . g r a i n s i z e vs_. s o r t i n g ,  m i n e r a l i z e d was d e t e r m i n e d .  grain  proportion  each o t h e r .  centage m a t r i x , and p e r c e n t a g e m a t r i x vs_. s o r t i n g ) wi.th both v a r i a b l e s  of s o r t i n g ,  miner-  In each o f  grain  s i z e vs.  the p r o p o r t i o n o f  The t h r e e m a t r i c e s  the  per-  rocks thus  gen-  e r a t e d a r e shown i n f i g . 46 w i t h p r o p o r t i o n m i n e r a l i z e d w i t h c h a l c o c i t e w r i t t e n ' i n each b l o c k . a grain  In g r a i n s i z e vs_. s o r t i n g ,  rocks w i t h a s o r t i n g o f 4 and  s i z e o f R, a n d . w i t h a s o r t i n g o f 5 and g r a i n s i z e s  t a i n e d the most c h a l c o c i t e . with grain  sizes  In g r a i n s i z e v s .  L and R and 60 p e r c e n t m a t r i x  percentage (fine  o f R and L, m a t r i x the  con-  blocks  f r a c t i o n ) , grain size  of  _(_ and 50 p e r c e n t m a t r i x , and g r a i n s i z e R w i t h 70 p e r c e n t m a t r i x had more . c h a l c o c i t e than o t h e r v a r i a b l e c o m b i n a t i o n s tage m a t r i x vs.. s o r t i n g  the g r e a t e s t  o f these  concentrations  two.  Finally  of c h a l c o c i t e  in percenoccurred  where s o r t i n g was 4 and 50 p e r c e n t m a t r i x , s o r t i n g was 5 and 60 p e r c e n t and where t h e s o r t i n g was 4 o r 5 and the m a t r i x was 70 p e r c e n t o f the When a l l 47),  i t becomes  portions  apparent  This area  percentage  matrix  is.where  conglomerates rocks,  sorting  (fig.  the h i g h e s t  pro-  there-  mineralized variables  i s 5, g r a i n s i z e  i t was found t h a t  in comparing  and c h a l c o c i t e o c c u r r e n c e , made the rocks  m i n e r a l i z a t i o n was  matrix  This area  ( i e . optimum combined v a r i a b l e s  conducive  f o r ' i r r e g u - l a r i t y i n tha a r e a l  vo1 c a n i c l a s t i c  of highly  rock.  present  pre-  in a c t u a l  i s e i t h e r L o r R,  and  i s 60 p e r c e n t .  In c o n c l u s i o n ,  reason  i s an a r e a where some o f  the d i f f e r e n t c o m b i n a t i o n s  i n the h o s t v o l c a n i c s  rock).  these  that there  into a three dimensional  of c h a l c o c i t e mineralized for a l l plots c o i n c i d e .  fore defines sent  t h r e e p l o t s a r e combined  matrix,  certain physical  variables  e x t e n t s o f the o r e  of  the  characteristics  to b e i n g m i n e r a l i z e d .  r e s t r i c t e d to c e r t a i n f a c i e s , o r  pile;  lithic  lenses  Thus, is  the  that  interbeds, within  the the  of  % OTHER  OTHER  .0612 n =49  LU N  L  if)  < DC  O  R  5 0 % . 1 2 5 i >3 Tl  =112  .1765  .2222  n = 17  n = 18  .3478  .2925  n = 23  (  MATRIX  .3333 n =6  n = 147  .4286 n = 21  6.0  %  p 5  2T  n = 119  44000 n =5  .6132 n = 106  .3571 n = 28  •  7 0 % ].2^i3!,', '•n =| 42 ;!  !  1 ;  r.0000 n =1  .5 0 8 5 n = 59  .3333 n = 21  F i g u r e 4 6 : Comparison o f d i f f e r e n t types o f s i g n i f i c a n t l y c h a l c o c i t e r m i n e r a l i z e d v a r i a b l e s w i t h each o t h e r i n rock type AGGR. a) Comparison o f s i g n i f i c a n t l y m i n e r a l i z e d p e r c e n t m a t r i x v a l u e s w i t h s i g n i f i c a n t l y m i n e r a l i z e d v a l u e s o f g r a i n s i z e i n rock type AGGR. n v a l u e s i n each b l o c k i n d i c a t e n o . o f o b s e r v a t i o n s o f t h e g i v e n v a l u e s t o g e t h e r . i n AGGR. P r o p o r t i o n o f e a c h o f t h e s e i n t e r s e c t i o n s m i n e r a l i z e d w i t h c h a l c o c i t e i s p r e s e n t e d i n b o l d numerals i n each b l o c k .  o  SORTING  OTHER  N  L  R  (  OTHER  4  5  .1467  .1667  .2603  n = 225  .1429  n =24  n =73  .0000  .6667  n =35  n =0  .4237  .5313  n =177  n =32  n =6  .5094 n =106  .4333  .1429  .3590  n = 30  n =7  n =39  F i g u r e ' l 6 b : Comparison o f s i g n i f i c a n t l y m i n e r a l i z e d s o r t i n g and g r a i n s i z e v a l u e s i n AGGR. E x p l a n a t i o n o f each b l o c k i s t h e same as i n f i g . ' i 6 a .  % OTHER  OTHER  n = 78  o z H DC  o  .1282  .0000 4 n =4  5  . .4615 n = 13  50  MATRIX %  .1949 n = 195  n =138  .3636  n = 20  n =33  n = 63  ;!  .3913  .5000  .3492  70  6 0 %  .4713 n = 87  :  %  . 4 28 6 n = 56  .0000 n =6  .3607 n = 61  F i g u r e 4 6 c : Comparison o f s i g n i f i c a n t l y m i n e r a l i z e d s o r t i n g and p e r c e n t m a t r i x v a l u e s i n AGGR. B l o c k d e s c r i p t i o n s ' as i n f i g . 4 6 a . ( A l l t h r e e o f t h e s e f i g u r e s (_i_e. 4 6 a , b , c ) a r e draughted versions o f computer-retrieved t a b u l a t i o n s ) .  SORTING Figure 47: Optimum o r e h o r i z o n d i a g r a m . T h i s diagram i s a c o m b i n a t i o n o f the t h r e e f i g u r e s i n f i g . 4 6 . M o . ' s i n each b l o c k r e p r e s e n t the p r o p o r t i o n s o f the v a r i a b l e i n t e r s e c t i o n s m i n e r a l i z e d . T h i s d i a g r a m shows t h a t t h e r e i s an a r e a (shaded) where a l l t h r e e v a r i a b l e s have a common h i g h p r o p o r t i o n o f m i n e r a l ization. Thus any AGGR h o r i z o n w i t h the p h y s i c a l c h a r a c t e r i s t i c s as d e f i n e d by t h i s a r e a would be p r e f e r e n t i a l l y m i n e r a l i z e d r e l a t i v e to o t h e r s u b - t y p e s o f AGGR and r e l a t i v e to o t h e r rock t y p e s .  109 Chemistry of  5-2.5  the Ore Lenses  5 . 2 . 5 ( a ) P r o b a b i l i t y P l o t o f Assay  Data  A p r o b a b i l i t y p l o t o f assay data f o r the n i n e t e e n h o l e s s t r u c t e d u s i n g methods d e s c r i b e d by S i n c l a i r  (1976)-  from d a t a o b t a i n e d by F a l c o n b r i d g e N i c k e l Mines L t d . for  twenty f o o t s a m p l i n g  intervals.  con-  Assay v a l u e s were  taken  The a s s a y s u s e d , were  Not a l l the a s s a y s were i n twenty f o o t  i n t e r v a l s but the a u t h o r combined i n t e r v a l s o f f i v e and/or get twenty f o o t  s t u d i e d was  i n t e r v a l v a l u e s where p o s s i b l e ,  ten f e e t i n o r d e r  i f a given shorter  to  section  c o u l d not be combined to y i e l d a s t a n d a r d twenty f o o t v a l u e then the a s s a y v a l u e s were d i s c a r d e d f o r the purposes  o f the p l o t .  In t h i s manner, one  d r e d and s e v e n t y - s e v e n a s s a y v a l u e s were used to c o n s t r u c t the graph  (fig.  The a s s a y data i n d i c a t e a bimodal d i s t r i b u t i o n o f v a l u e s , w i t h an t i o n p o i n t a t 60 p e r c e n t . accounts  Thus p o p u l a t i o n A, w i t h the h i g h e r assay  hun-  inflec-  values,  f o r 60 p e r c e n t o f the v a l u e s p r e a d , w h i l e p o p u l a t i o n B a c c o u n t s  40 p e r c e n t .  The upper p o p u l a t i o n A i s  i n f e r r e d to r e p r e s e n t copper  48).  for  values  present  i n t h e m i n e r a l i z e d z o n e s , whereas B r e p r e s e n t s background c o p p e r c o n -  tents.  T h r e s h o l d f o r p o p u l a t i o n A (from the lower two p e r c e n t i l e )  as  is  indicated  180 ppm c o p p e r , and the t h r e s h o l d f o r B (from i t s upper two p e r c e n t i l e )  found t o be 300 ppm c o p p e r . either  i n the range  185~300 ppm can b e l o n g  to  population.  The i n t e n s e there  Values  is  i n f l e c t i o n p o i n t o f t h i s bimodal d i s t r i b u t i o n i n d i c a t e s  that  i s a v e r y s t r o n g d i f f e r e n t i a t i o n and d i s t i n c t i o n between m i n e r a l i z e d  zones and background c o n t e n t s l a t i o n to a n o t h e r , and thus relatively  (|_e. t h e r e i s no r e a l g r a d a t i o n from one. popu-  the m i n e r a l i z e d zones a r e a v e r y d i s t i n c t f e a t u r e  u n r e l a t e d to background  values).  5.2.5(b) T r a c e Element C h e m i s t r y o f Ore Lenses Analyses  f o r Zn, Cu, N i , Rb, and Sr were done f o r s i x  These s e t s were taken from c o u n t r y rock s u r r o u n d i n g  sets of  the z o n e s ,  samples.  in o r d e r  a s c e r t a i n what c h e m i c a l v a r i a t i o n s o c c u r between a m i n e r a l i z e d lens and  to its  no  F i g u r e 48: P r o b a b i 1 i t y graph o f copper assay v a l u e s . " T h e p e r c e n t copper i s based on twenty f o o t assay i n t e r v a l s . One hundred and s e v e n t y - f i v e assay v a l u e s are r e p r e s e n t e d on t h i s graph. ' '  111 host- r o c k s .  T a b l e 7 shows t h e a n a l y s e s  r e p o r t e d a r e based on two a n a l y s e s  f o r the various  o f the samples  sets.  The v a l u e s  by means o f X - r a y  fluorescence.  Some s a m p l e s , w i t h h i g h copper c o n t e n t s , were checked by a t o m i c a b s o r p t i o n methods, and t h e r e s u l t s were combined w i t h those from t h e XRF a n a l y s e s the r e s u l t a n t average v a l u e .  D i s c u s s i o n o f the chemistry w i l l  d e s c r i p t i o n o f each sample s e t ( see a t t a c h e d map f o r sample  to y i e l d  involve  locations).  In t h e f i r s t s e t o f samples; 44A1 i s from 2.85 m below t h e c o l l a r o f DDH 44,  i t i s a c o n g l o m e r a t e w i t h d i s s e m i n a t e d n a t i v e c o p p e r , 44B2, 21.33 m below,  has s t r o n g n a t i v e copper m i n e r a l i z a t i o n through  t h e m a t r i x w i t h minor c h a l c o c i t e ,  44B8, from a depth o f 4 4 . 7 m, c o n t a i n s p y r i t e , and f i n a l l y totally  d e v o i d o f any s u l p h i d e .  c o p p e r , whereas  Both 44A1 and 44B2 c o n t a i n n e a r l y 2 p e r c e n t  t h e p y r i t e zone has 0.01 p e r c e n t copper and t h e u n m i n e r a 1 i z e d  a r e a , <0.01 p e r c e n t . rubidium.  44C1 (54.12 m) i s  Strontium is strongest  i n t h e p y r i t e z o n e , as i s  The two c o p p e r - r i c h samples a r e d e p l e t e d i n r u b i d i u m , r e l a t i v e t o  the o t h e r two s a m p l e s .  Z i n c i s f a i r l y c o n s t a n t and n i c k e l i s lowest i n t h e  u n m i n e r a l i z e d sample. Sample 6A7 i s u n m i n e r a 1 i z e d c o r e from 35.88 m i n DDH 6, 6A8 (39.01 m)has t r a c e c h a l c o c i t e i n c a r b o n a t e patches  i n the m a t r i x , 6B3 (84.9 m) i s from a h i g h -  grade copper zone where t h e framework i s open, 6C9 (84.9 m) i s from an unminera l i z e d a r e a . Copper decreases  i s v e r y abundant  i n 6B3, a p p r o a c h i n g  s i g n i f i c a n t l y from the o r e zone t o a low a t 6C9. Z i n c shows a s l i g h t  e n r i c h m e n t i n 6B3, and u n i f o r m i t y i n t h e o t h e r s a m p l e s . richer  10 p e r c e n t , and  i n 6B3, and l e s s  o t h e r s where  i n 6C9.  i t is constant.  Nickel  is s l i g h t l y  S t r o n t i u m i s much h i g h e r - i n 6B3 than i n t h e  Rubidium i s lowest i n 6B3 and h i g h e s t  i n 6A7.  Sample W32A i s from t h e m i d d l e o f a s t r o n g c h a l c o c i t e - b o r n i t e l e n s on t h e n o r t h s i d e o f t h e c i r q u e , W97GM i s o f groundmass t o c o n g l o m e r a t e i m m e d i a t e l y below W32A ( i t has some v i s i b l e c h a l c o c i t e and b o r n i t e i n gangue). a u g i t e porphyry c l a s t s e t i n t h e groundmass o f W97GM, and W i l l m i n e r a l i z e d v e i n zone 18 m below W32A.  Copper i s very abundant  p e r c e n t and i s r i c h e r i n t h e groundmass  (W97GM)  than i n a c l a s t  W97AP i s an  is wall  rock o f a  i n W32A, o v e r 6 (W97AP).  TABLE VI I TRACE ELEMENT ANALYSES FOR ORE LENS SETS Cppm I p r e c i s i o n ) Ni  Sjr  Rb  2 1 . 2 9 ( H .87) 17.75(10.59) 12.44(12.01) 4.88(H)  70.24(10.37) 245.07(10.26) 571.65(10.90) 367.23(10.23)  1.38(10.23) 5.43(10.13) 49.69(10.06) • 17.19(10.23)  240.72(14.17) 2228.72(1217.48) 94894.80(14205.65) 63.33(11.91)  18.91(10.74) 15.27(10.96) 30.94(10.86) 5.39(10.02)  237.74(10.08) 192.33(10.05) 546.41(+0.53) 232.64(10.10)  21.71(10.05) 20.61(10.05) 1.30(10.38) 9.22(10.24)  78.71(10.16) 165.08(12.37) 188.425(10.94) 170.81(12.84)  123.91(118.12) 61794.55(1750) 1832.52(1169.53) 5569.56(1504.71)  8.21(10.29) 61.08(10.81) 83.70(10.06) 22.24(10.18)  268.46(10.55) 261.13(10.37) 352.71(10.29) 270.79(10.20)  12.42(10.19) 0.85(10.16) 18.2(10.05) 22.52(10.24)  W2 W3 W4  111.33(16.06) 83.25(10.81) 61.32(10.39)  32913.80(+1586.2) 183.89(164.20) 86.75(10.75)  35.25(18.15) 27.68(10.90) 31.25(11.72)  176.64(10.07) 101.23(10.03) 99.64(10.50)  2.03(10.26) 2.33(10.14) 0.68(10.25)  132C 3 132C7  96.50(12.66) 84.54(12.06)  42.71(11.71) 101.21(12.78)  10.95(11.14) 19.50(10.43)  150.22(10.55) 687.64(12.52)  90.91(10.72) 12.06(10.28)  W12 W13  156.38(12.29) 92.85(10.05)  56504.45(11895.90) 1163.26(130.77)  37.76(10.10) 27.57(11.68)  857.69(116.17) 467.02(10.8'))  20.58(10.21) 18.64(10.39)  W98  125.52(11.00) 73.00(10.96) 94.37(11.00)  10674(1994.75) 147.75(137.77) 7128.48(10.19)  39.18(10.35) 73.39(±1.14) 20.44(10.15)  206.45(10.10) 321.12(11.04) 189.48(10.06)  1 .91(10.30) 11 .62(10.02) 6.88(10.18)  Sample No. 44A1 44B2. 44B8  44C1 6A7 6A8  6B3 6C9 W11 1 W32A W97AP W97GM  W 9 9  W103  Zn_ 131.40(±1.37) 113.60(12.82) 97.64(11.99) 76.51(11.34) 88.44(12.29) 86.09(10.30) 183.50(15.77) 90.11(11.44)  Cu 15558(11.40) 18071.10(10.55) 1 15.94.(113.26) 56.75(±2.19)  '.  113 Copper  is p r e s e n t  i n t r a c e amounts at the bottom o f the m i n e r a l i z e d a r e a .  Z i n c i s most abundant and s e c o n d a r i l y so  i n the c o p p e r - r i c h p o r t i o n s .  i n W32A.  Strontium is f a i r l y  Nickel  is highest  i n W97AP,  c o n s t a n t and r u b i d i u m shows  a g r e a t d e p l e t i o n i n the most h i g h l y m i n e r a l i z e d s a m p l e . Sample W2 i s  f r o m the c e n t r e o f a s m a l l , 0.3  w e s t e r n edge o f the South Zone.  W3 was taken from 1.5  and W4 f o r 1.5 m above t h e l e n s .  Zinc is highest  what lower above the zone than under i t . lower  i n W3 and W4.  dium i s  Nickel  t h i c k , o r e lens a t the  m  Copper  is very high  is constant, strontium is highest  low i n W4 r e l a t i v e t o samples W2 and  Copper  somewhat s t r o n g e r  t i u m i s much s t r o n g e r  i n W2 and  levels  barren  i n b o t h samples,  Z i n c and n i c k e l are c o n s t a n t .  i n 132C7 w h i l e the r e v e r s e  is true for  a t W12 and has  WI3 comes  some m a l a c h i t e - s t a i n i n g .  c e n t ) and i s h i g h e r  than background  in W13-  two, w h i l e s t r o n t i u m i s more abundant than i n W13. W98  Rubidium is present  i s a specimen o f w a l l  is  richest  Nickel  i n W12.  Zinc  i n s i m i l a r amounts  work and the c o p p e r m i n e r a l s are p r e s e n t  This  host  is  Stron-  lens lenses  i n W12 (over 5 p e r - ,  i s about even between the i s more p r e v a l e n t i n W12 in both.  rock t o the dyke t h a t c o n t a i n s  n a t i v e copper w i t h a t r a c e o f c h a l c o c i t e .  A sample 1.5 m from W98  from 9 m above t h e two  Copper  but  rubidium.  W12 i s the c e n t r a l p a r t o f a c h a l c o c i t e - b o r n i t e - c h a l c o p y r i t e o r e on the s o u t h e r n edge o f the c i r q u e .  rubi-  i s a b l e a c h e d a r e a which  m below 132C3 and i s  i s p r e s e n t as background  i n the b a r r e n c o r e .  i n W2 and much  W3.  1 p e r c e n t p y r i t e , 132C7 i s from 29.1  conglomerate.-  horizon  i n the o r e zone and some-  132C3, from 183 m below the c o l l a r o f DDH 132, contains  m below t h i s  disseminated  rock has a c l o s e d f r a m e -  i n q u a r t z - f i l l e d pores  i n the m a t r i x .  (W103) i s of a rock w i t h a medium to c o a r s e sandy-  m a t r i x and open framework.  This  specimen has minor amounts o f n a t i v e copper  and c h a l c o c i t e i n q u a r t z p o r e s , but s t r o n g n a t i v e copper m i n e r a l i z a t i o n i s p r e s e n t as d i s s e m i n a t i o n s  through  lithic  m i n e r a l i z a t i o n - f r e e dyke rock by W98.  clasts.  F i n a l l y , W99 i s  copper  The t r a c e element c h e m i s t r y shows t h a t  114 z i n c ' i s most abundant  i n the c o p p e r - r i c h s a m p l e s .  ground c o p p e r v a l u e s . In summary,  WS9 has t y p i c a l  N i c k e l , s t r o n t i u m and r u b i d i u m a r e h i g h e s t  some general  in W39•  r e l a t i o n s h i p s o f t r a c e elements and copper  m i n e r a l i z a t i o n can be gleaned from the a n a l y t i c a l d a t a . u s u a l l y have t h e i r g r e a t e s t c o n c e n t r a t i o n s f a i r l y c o n s t a n t through  back-  Z i n c and s t r o n t i u m  in c o p p e r - r i c h areas.  the rocks however t h e r e may be a s l i g h t  enrichment  i n the c o p p e r zones  (nickel  than whole r o c k s ) .  Rubidium i s a p p a r e n t l y d e p l e t e d i n copper a r e a s .  it  is  is strongest  N i c k e l .is  in sing1e vol canic c l a s t s ,  i n t e r e s t i n g t o see the sharp c u t o f f  t h e i r host  rocks  copper v a l u e s probability content,  (eg. W2-W3-W4).  It seems  Also  i n grade between o r e l e n s e s  and  t h a t t h e r e i s no g r a d a t i o n o f  between the two a r e a s , w h i c h a g r e e s w i t h what was seen  p l o t o f assay v a l u e s .  rather  i n the  No a r e a s have a g r e a t d e p l e t i o n i n c o p p e r  t h e r e ' a r e p l a c e s w i t h low background  c o n t e n t s , but c o n s i s t e n t  from w h i c h c o p p e r has been removed t o be p r e c i p i t a t e d e l s e w h e r e a r e not Background  c o p p e r c o n t e n t s , as d e t e r m i n e d from t h e s e a n a l y s e s ,  the h i g h b a c k g r o u n d t i o n 3-3-10 5.2.5(c)  and'W13.  major oxide analyses,  increase  i n T a b l e 8, were c a r r i e d out on samples  i n CaO in the o r e  Gangue M i n e r a l o g y o f the Ore Ore m i n e r a l s  identical  Lenses  in SiO^, MgO  W12  (strong  Na^O and K^O i n h i g h l y m i n e r a l i z e d a r e a s vs_. l e s s m i n e r a l i z e d ,  and the s t r o n g 5-2.6  (sec-  above).  The most s i g n i f i c a n t f e a t u r e s a r e d e p l e t i o n s  depletion),  seen.  agree w i t h  copper v a l u e s found i n c l a s t s and o t h e r rock types  M a j o r Oxide Chemistry o f Ore  Partial  zones  lens.  Lenses  i n the lenses a r e i n t i m a t e l y i n t e r g r o w n w i t h gangue m i n e r a l s  t o t h o s e formed by metamorphism o f the h o s t  dant s u l p h i d e s  rocks.  c o n t a i n l a r g e amounts o f e p i d o t e and p r e h n i t e .  a t e and c h l o r i t e a r e a l s o common i n t h e s e z o n e s .  Zones o f Quartz,  In thus appears  morphic and o r e m i n e r a l s have formed by the same s o r t o f  abuncarbon-  that meta-  processes.  115  TABLE MAJOR  OXIDE  VIII  ANALYSES  FOR  ORE  LENS  SET  (%)  WI 2  OXIDE  WI 2  S i 0  43.13  46.50  0.91  0.96  1 5.20  1 5.86  2.91  3.64  MnO  0.11  0.1 7  MgO  1 .75  6.35  CaO  9.65  5. 30  Na 0  3.25  K 0  0.66  1 .70  0.64  0.81  Ti 0  2  A1 0  3  2  1  2  **  Fe * *  2  2  p o 2  5  :  4.13  3. 76  L.O.I.  -0.49  Cu  5. 65  0.12  83.37  89.3  Total  Possible Total  *  Oxidation  Fe and T i 0^ are low because t i t a n i f e r o u s m a g n e t i t e  was not d i s s o l v e d c o m p l e t e l y i n the a n a l y t i c a l p r o c e d u r e "»»»»»These a n a l y s e s were done by Min-En L a b o r a t o r i e s , Vancouver, B.C..  North  116 The o r e lens sample l o c a t i o n near W104 ( f i g . 49)  has v e r y  e p i d o t e development w i t h s t r o n g p r e h n i t e , c a r b o n a t e and q u a r t z C h a l c o c i t e and b o r n i t e are p r e s e n t as and p r e h n i t e a l t e r a t i o n p a t c h e s . mineral  intense overgrowths.  i r r e g u l a r l y shaped g r a i n s  in e p i d o t e  F i g . 50 shows these o r e and metamorphic  intergrowths.  In the lens a t the head o f the c i r q u e (W112), g r a i n s the open m a t r i x of the host c o n g l o m e r a t e s .  of s u l p h i d e occur  Best development o f the  i s seen where they e i t h e r have e p i d o t e rims o r a r e i n t e r g r a n u l a r  in  sulphides  to q u a r t z .  In  r a r e p l a c e s where c h l o r i t e and c a r b o n a t e overgrow and r e p l a c e p l a g i o c l a s e grains, this  o r e m i n e r a l s a r e i n t e r g r o w n w i t h them.  lens  (W22), opaques  the m a t r i x .  'speckle'  (or dust)  A p p r o x i m a t e l y 5 to 6 m above  p r e h n i t e and e p i d o t e t h a t a l t e r  Sample W17, from near t h i s a r e a , shows the same s t r o n g  o f p r e h n i t e and e p i d o t e w i t h o r e ( f i g . In the W32A lens no o r i g i n a l  speckling  5?).  l i t h i c grains  a r e v i s i b l e as they a r e a l l  overgrown by kS p e r c e n t p r e h n i t e , 30 p e r c e n t e p i d o t e , 10 p e r c e n t q u a r t z w i t h l e s s e r amounts o f z o i s i t e , p u m p e l l y i t e and c h l o r i t e . of very  large,  consists  i r r e g u l a r patches o f p r e h n i t e w i t h i n t e r g r a n u l a r q u a r t z and .  l a r g e masses o f largest,  The rock now  i n t e r c o n n e c t e d , s m a l l e r , e p i d o t e and z o i s i t e g r a i n s .  i r r e g u l a r l y - s h a p e d s u l p h i d e s o c c u r i n the q u a r t z p a t c h e s ,  The  i n which  t h e r e a r e g e n e r a l l y s t r a i g h t edges on the opaques where they a r e i n c o n t a c t w i t h the q u a r t z .  S m a l l e r g r a i n s o f s u l p h i d e a r e s c a t t e r e d through the p r e h -  n i t e or epidote ( f i g .  52).  Sample W10, from the l e n s on the south s i d e o f the c i r q u e (see l o c a t i o n on a t t a c h e d map) c o n t a i n s  sample  l a r g e patches o f c a r b o n a t e w i t h c h l o r i t e ,  q u a r t z , e p i d o t e , and z o i s i t e i n the m a t r i x .  The s u l p h i d e s ( b o r n i t e , c h a l c o c i t e  and c o v e l 1 i t e ) o c c u r i n t h r e e a r e a s ; w i t h c h l o r i t e , q u a r t z , e p i d o t e and z o i s i t e after  f e l d s p a r s , or  in c a r b o n a t e - e p i d o t e patches  i n the m a t r i x .  Sample W11,  from the same a r e a , has ore m i n e r a l s , up to 0.15 mm. i n d i a m e t e r in l a r g e ' c h l o r i t e patches patches.  i n the m a t r i x , and even l a r g e r g r a i n s are p r e s e n t - i n q u a r t z  Opaques are a l s o p r e s e n t  in the e p i d o t e g r a i n s  and, t o a minor  117  F i g u r e 49: W104.  C l o s e up o f o r e l e n s e s at sample l o c a t i o n  Note i n t e n s e e p i d o t e a l t e r a t i o n w i t h the very  strong sulphide concentration.  Fresh s u r f a c e s  s u b t l e r e d d i s h t i n g e to m i n e r a l i z e d rock due to hematite.  F i g u r e 50:  show a secondary  The w i d t h o f t h i s p l a t e i s about 1.8 m..  Photomicrograph o f W104 o r e lens  Opaque g r a i n s  (x-nicols).  of c h a l c o c i t e and b o r n i t e are i n t i m a t e l y  i n t e r g r o w n w i t h h i g h l y b i r e f r i g e n t e p i d o t e ( w i t h minor prehnite)  grains.  This  section is  1.1  cm a c r o s s .  118  F i g u r e 51: sample W17  Photomicrograph o f opaque m i n e r a l s and gangue-(piane-polarized) .  with lesser epidote.  The main gangue i s  Sulphides  ( b o r n i t e and c h a l c o c i t e )  s p e c k l e gangue masses, l a r g e r s u l p h i d e g r a i n s w i t h gangue.  F i g u r e 52:  This  s e c t i o n i s 1.1  are  intergrown  cm a c r o s s .  Photomicrograph o f W32 ore lens  Large s u l p h i d e  prehnite  (x-nicols).  ( b o r n i t e and c h a l c o c i t e ) g r a i n s  are i n t e r -  grown w i t h b i r e f r i g e n t p r e h n i t e and e p i d o t e , and w i t h w h i t e quartz areas.  Note s t r a i g h t edges on s u l p h i d e s where they  are i n c o n t a c t w i t h q u a r t z . extremely a l t e r e d .  As can be seen, host  This s e c t i o n is  1.1  cm a c r o s s .  rock  is  119 extent,  in the c a r b o n a t e cement.  DDH 25 a t the n o r t h w e s t e r n edge o f the South Zone, does c o n t a i n numerous  p y r i t e zones.  the c o l l a r ) , p y r i t e o c c u r s  form o f c h l o r i t e .  i n the m a t r i x .  Sample 2A2 (from DDH 2)  round i n c l u s i o n  'balls'  Sample 6B3 had the h i g h e s t section this  rock was  b o n a t e , and q u a r t z . and r e l i c t  p r e h n i t e masses ( f i g . 54).  i n the c h l o r i t e cement ( f i g .  pre-  53)-  copper c o n t e n t ('v 10 p e r c e n t ) a n a 1 y s e d .  in pores  a l s o c o n t a i n opaque s u l p h i d e s  In t h i n  i n t h e i r groundmasses, i n a l t e r a t i o n patches  (up t o 2.7 by 0-3 mm) i s found i n e p i d o t e and A l l epidote grains  are h e a v i l y d u s t e d w i t h s u l -  i n t e r g r o w n w i t h q u a r t z and p r e h n i t e p a t c h e s .  (and l e s s commonly c h a l c o p y r i t e )  a l t e r a t i o n minerals.  I t s most common forms,  a r e as network masses which f i l l rims s u r r o u n d i n g  In  P y r i t e is  However, not a l l s u l p h i d e areas are i n t e r g r o w n w i t h gangue. is strongest  in t h i s  i s from a p y r i t e a r e a t o o .  R e l i c t c l a s t s have opaques  feldspar grains  Ore i s a l s o  is  i n t e n s e l y a l t e r e d by e p i d o t e (80 p e r c e n t ) , p r e h n i t e , c a r -  Best development o f s u l p h i d e  phides.  Chlorite  in t h i s specimen, however p y r i t e i s not  t h i s specimen the rock i s cemented by c a r b o n a t e and c h l o r i t e . s e n t as  it  In one such zone (25A5. from 7-62 m below  i n c h l o r i t e patches  a l s o seen to r e p l a c e a u g i t e s  i s b a r r e n , but  small  i t i s not g e n e r a l l y found w i t h i n areas o f h i g h c o n c e n t r a t i o n ,  the m a t r i x to l i t h i c  l i t h i c grains.  Where p y r i t e  clasts  ( f i g . 55),  o r as  In these forms the p y r i t e a c t s as  its  own a l t e r a t i o n medium, r e p l a c i n g m a t r i c e s by i t s e l f . In summary, copper s u l p h i d e s  a r e seen to be i n t i m a t e l y i n t e r g r o w n w i t h  e p i d o t e , p r e h n i t e , c a r b o n a t e , q u a r t z and c h l o r i t e . p l a c e s an e x c e p t i o n .  P y r i t e where r i c h ,  is  in  T h i s common s p a t i a l r e l a t i o n s h i p o f a l t e r a t i o n and o r e  m i n e r a l s e x p l a i n s some o f the chemical v a r i a t i o n s seen between o r e l e n s e s barren country rock.  The i n c r e a s e  in c a l c i u m and s t r o n t i u m i n o r e zones  and is  caused by the presence w i t h i n these zones o f c a r b o n a t e , formed by. the same m i n e r a l i z i n g e p i s o d e t h a t p r e c i p i t a t e d copper m i n e r a l s . f o r a decrease  in s i l i c a ,  This also  accounts  sodium, p o t a s s i u m and magnesium c o n t e n t s as  minerals  120  F i g u r e 53:  P y r i t e as  (plane-polarized).  rounded blebs  This  in c h l o r i t e  shows p y r i t e i s e p i g e n e t i c as  is  i n t e r g r o w n w i t h a secondary  is  1.1  gangue m i n e r a l .  This  Sulphides  (x-nicols).  This  'speckling'  section  e p i d o t e masses i n sample  sample a n a l y s e d o v e r 10 p e r c e n t copper  and t h i s f i g u r e shows the r e l a t i o n o f v e r y  birefrigent  e p i d o t e gangue and c h a l c o c i t e - b o r n i t e m i n e r a l i z a t i o n . section  it  cm a c r o s s .  F i g u r e 54: 6B3  ('balls')  is  1.1  cm a c r o s s .  This  121  Figure 5 5 : (white) ac r o s s .  Photomicrograph o f network p y r i t e masses  t h a t have r e p l a c e d m a t r i x .  S e c t i o n is  1.1  cm  122 c o n t a i n i n g these elements were p r e f e r e n t i a l l y broken down (_i_e. a u g i t e s and feldspars)  due t o the metamorphic a l t e r a t i o n .  5-3 S u l p h i d e - B e a r i n g  Veins  General Outcrop Appearance and Gangue M i n e r a l o g y  5.3-1  S i g n i f i c a n t amounts o f s u l p h i d e s though  are present  in gangue-rich  veins, a l -  t h e i r abundance o f c o n t a i n e d copper i s minimal compared t o o r e l e n s e s .  As p r e v i o u s l y s t a t e d , most metamorphic m i n e r a l s on the p r o p e r t y a r e o b s e r v e d in t h e form o f both v e i n and t a b u l a r metadomains.  However not a l l v e i n s  t a i n o r e m i n e r a l s and those t h a t do o c c u r i n l o c a l  steeply dipping  Dominant s u l p h i d e s  con-  swarms.  i n these v e i n s a r e c h a l c o c i t e , b o r n i t e , and c h a l c o p y r i t e ,  l e s s common a r e v e i n s w i t h p y r i t e o r n a t i v e c o p p e r . The most common v e i n m a t e r i a l s a r e c a r b o n a t e and q u a r t z . fairly  typical  Epidote is  a l s o , and p r e h n i t e i s seen m e g a s c o p i c a l l y t o a l e s s e r e x t e n t .  C o m b i n a t i o n s o f c a r b o n a t e , q u a r t z and e p i d o t e a r e found t o g e t h e r whereas p r e h n i t e - c a r b o n a t e - q u a r t z v e i n s a r e l e s s abundant. t i o n o f p r e h n i t e was not very c o n s i s t e n t , and subsequent  commonly,  Field  identifica-  thin section  study  has shown t h a t p r e h n i t e i s indeed common. In the North Zone v e i n s a r e b e s t developed near DDH 16. l o c a t i o n W36)quartz-epidote-carbonate bornite-chalcocite-digenite.  These  veins contain r i c h concentrations of v e i n s s t r i k e 010* t o 020* and d i p  v e r t i c a 1 l y "to- 80"SW, and p i n c h and s w e l l a l o n g t h e i r l e n g t h s from 5 o r 6 cm t o 3 mm) . full  Here (J_e_. sample  (widths  Copper s u l p h i d e ' s a r e not p r e s e n t f o r t h e  l e n g t h s of- the v e i n s but a r e c o n c e n t r a t e d i n pods where t h e v e i n s  reach  a maximum t h i c k n e s s .  strike  l e n g t h and swarms have a d e n s i t y o f two veins per 5 f t i n a d i r e c t i o n  p e r p e n d i c u l a r to s t r i k e .  Individual  v e i n s a r e as much as 3.6"m i n  The gangue morphology  i s i n t e r e s t i n g where w e l l  d e v e l o p e d , as i t shows s u l p h i d e c o n c e n t r a t i o n i n c e n t r e s o f v e i n s w i t h q u a r t z , whereas tals.  t h e v e i n edges a r e composed o f c a r b o n a t e and e l o n g a t e e p i d o t e c r y s In patches o f massive s u l p h i d e , s m a l l e u h e d r a l q u a r t z c r y s t a l s a r e  123 common, growing Also eral  in vugs i n the s u l p h i d e mass.  in the North Zone are two areas o f s t r o n g  coatings.  W.95 and W100.  The major zone i s  in the a r e a o f sample l o c a t i o n s W40-W41-W42,  Near W40-W41-W42 the dominant f r a c t u r e d i r e c t i o n i s  However t h e r e are q u a r t z and q u a r t z - c a r b o n a t e v e i n s 70SE.  f r a c t u r i n g with ore min-  The q u a r t z v e i n s a r e s i n u o u s .  with chalcocite.  The host  Intergrown w i t h these v e i n s are b o r n i t e  in t h e i r m a t r i c e s .  f a c e s commonly have copper moss c o a t i n g s . and c a r b o n a t e - q u a r t z v e i n s  t h a t c u t through a t 020/  rock to the f r a c t u r e systems  and b o r n i t e i n q u a r t z - f i l l e d pores  165/84E.  contains chalcocite Exposed f r a c t u r e  sur-  Around W95 and W100. the f r a c t u r e s  have common t r e n d o f 025/75SE.  Wall  these v e i n - f r a c t u r e s c o n t a i n l a r g e , open, q u a r t z - f i l l e d a r e a s  rocks  to  i n the m a t r i c e s  f i l l e d w i t h c h a l c o c i t e and b o r n i t e . A second f r a c t u r e zone i s near DDH kh. veins.  These j o i n t s  The host  rocks  (W33)  (037/vertical)  There a r e o n l y j o i n t s h e r e , no  have m a l a c h i t e and/or copper moss c o a t i n g s .  c o n t a i n 5 p e r c e n t d i s s e m i n a t e d n a t i v e copper .  Below the o r e l e n s a t W32,  q u a r t z - c a r b o n a t e v e i n s , w i t h 5 to 10 mm i n  diameter c h a 1 c o c i t e - b o r n i t e g r a i n s ,  occur.  3 cm w i d e , c u t through a green host  rock.  p r e s e n t on t h e i r s u r f a c e s .  The v e i n s , which a r e m a i n l y 2 to Minor m a l a c h i t e and copper moss are  The s u l p h i d e g r a i n s  a r e i n t e r g r o w n w i t h the gangue  m i n e r a l s and o n l y r a r e t r a c e s o f s u l p h i d e are p r e s e n t veins  do not c u t a c r o s s  the o r e l e n s .  in the h o s t  rocks.  S i m i l a r l y , below the second ore  These  lens  h e r e , a n o t h e r group o f q u a r t z - c a r b o n a t e - e p i d o t e - s u l p h i d e m i n e r a l i z e d v e i n s (028/88NW) crop out  (WHO).  These 1.25  to 15 cm wide v e i n s c o n t a i n 10 to 15  p e r c e n t b o r n i t e , c h a l c o c i t e , d i g e n i t e and c o v e l l i t e , w i t h a t t e n d a n t m a l a c h i t e and a z u r i t e .  Two to t h r e e cm wide e p i d o t e v e i n s , w i t h minor s u l p h i d e ,  through the rocks j u s t above the W104. o r e lens dipping veins  have the same g e n e r a l  ( f i g . 5&).  s t r i k e as those a t W36.  cut  These v e r t i c a l l y Numerous  small,  < 1 mm w i d e , c a r b o n a t e v e i n l e t s c u t through the ore h o r i z o n a t sample l o c a t i o n s W10-W11-W12.  These v e i n l e t s are s t r o n g l y m i n e r a l i z e d w i t h c h a l c o p y r i t e ,  124  F i g u r e 56:  Epidote v e i n l e t s c u t t i n g country  l y i n g W104 ore l e n s . surface  rock  over-  The i n t e n s e red c o l o u r a t i o n on the  i s the ' c o p p e r m o s s ' .  The e p i d o t e v e i n l e t s  are  not very wide h e r e .  F i g u r e 57:  A b o r n i t e and c h a l c o p y r i t e pod in a c a r b o n a t e -  q u a r t z v e i n near W76. a l t e r a t i on.  Note the s t r o n g m a l a c h i t e and a z u r i t e  125 which l o c a l l y makes up to 50 volume p e r c e n t o f the v e i n l e t . Near sample  l o c a t i o n s W115 and W116  (see geology  c i t e - b o r n i t e m i n e r a l i z e d v e i n s are seen 79NE) c o n t a i n s writer,  i n the host  map)  rock.  The o l d e r s e t  the o n l y o u t c r o p o c c u r r e n c e o f g r e e n o c k i t e  the younger  set  (036/vertica1)  c h a l c o c i t e are present  two s e t s o f c h a l c o -  l o c a t e d by  c o n t a i n no g r e e n o c k i t e .  in a c a r b o n a t e - q u a r t z - e p i d o t e v e i n  (117/  this  M a l a c h i t e and  (024/74SE) at  sample  l o c a t i o n W15. Two s e t s o f v e i n s c o n t a i n i n g s u l p h i d e s The o l d e r s e t  W49-  (090/66S) c o n s i s t s  wide e p i d o t e - c a r b o n a t e - q u a r t z v e i n s . ore l e n s a t W2, where i t appears does not o c c u r above the l e n s .  a r e a l s o p r e s e n t by sample a r e a  o f c h a l c o c i t e and m a l a c h i t e i n 3 to 40 mm One o f these v e i n s  i s connected w i t h the  to t r u n c a t e one s i d e o f the l e n s . The younger  set of veins  t r a c e c h a l c o c i t e in e p i d o t e - c a r b o n a t e - q u a r t z  (60/76SE) contain  gangue.  In the c e n t r a l p o r t i o n o f the South Zone, a group o f s u l p h i d e - r i c h veins  crop o u t .  At sample  bonate-epidote-bornite-malachite vein  isolated,  (145/50NE),  To the south o f DDH 88, near the top o f a s m a l l w a t e r f a l l , a 6.35  t h e i r selvages. c o n t a i n no  This vein is c r o s s - c u t  rock.  which e x h i b i t copper moss a l o n g  by o t h e r v e i n s  (065/vertica1),  which  sulphides.  A series  of veins with intense sulphide m i n e r a l i z a t i o n occurs  general  regions  country  rock a t 112/64NE.  o f DDH s 41 and 120.  s u l p h i d e v e i n zone.  1  This  At DDH 120, a s t r o n g  f a u l t occurs  i n the  fault disrupts  a l o n g what appears  the  to be a t h i c k  Through the s t r i k e o f the f a u l t from DDH 120 t o 60 m d i s -  t a n t , c a r b o n a t e zones c o n t a i n numerous At W80  cm wide  (110/68NE) c u t s the c o u n t r y  p a r t i c u l a r v e i n has f r a c t u r e o f f s h o o t s  car-  Sample W56 has a  carbonate-epidote-chalcocite-chalcopyrite-ma1achite-azurite vein  This  thick,  l o c a t i o n W55, a 7-5 cm t h i c k ,  (110/62NE) o c c u r s .  epidote-quartz-carbonate-malachite-vein  The v e i n  patches o f h i g h - g r a d e  c a r b o n a t e m a t e r i a l c o n t a i n s massive  sulphide  minerals.  b l e b s of c h a l c o p y r i t e (up t o 3 cm  in d i a m e t e r ) and b o r n i t e (up to 10 cm in d i a m e t e r ) .  Some o f the c h a l c o p y r i t e  126 e x h i b i t s excellent botryoidal textures  in the carbonate.  W8l samples  show  a c a r b o n a t e v e i n zone w i t h b o r n i t e - c h a l c o c i t e and c o v e l l i t e .  F i v e t o t e n mm  w i d e , pure v e i n s o f s u l p h i d e a r e seen t o invade the host  in places  These v e i n s a r e c r o s s - c u t  by e p i d o t e - c a r b o n a t e ones  rock  (041/80SE).  A t sample  l o c a t i o n W79, a 5 cm wide e p i d o t e - c a r b o n a t e v e i n zone i s p r e s e n t . (040/&6NW) c o n t a i n s ized veins  cross-cut  Through  two s e t s o f u n m i n e r a l i z e d v e i n s  (060/80NW  and 120/58NE).  -  The gangue m i n e r -  a r e complex i n t e r g r o w t h s o f c h a l c o -  pyrite-bornite-chalcocite-malachite.  The v e i n s p i n c h and s w e l l ,  < 1 cm, e x t e n s i v e l y  the s u l p h i d e s  p y r i t e t o massive  in t h e i r lengths,  bornite with chalcopyrite ( f i g . 5 7 ) .  sample l o c a t i o n W67, c a r b o n a t e - e p i d o t e - q u a r t z v e i n s pyrite-bornite-cha1cocite-ma1achite. rapidly.  W71  samples  Three t o f o u r p e r c e n t  extensively, (138/59NE)  disseminated  rock.  that the s u l p h i d e - m i n e r a l i z e d veins  Zone g e n e r a l l y s t r i k e n o r t h e a s t e r l y and a r e more o r l e s s  i n the North  vertical,  whereas  those  i n t h e South Zone s t r i k e n o r t h w e s t e r l y and d i p t o t h e n o r t h e a s t .  5.3.2  Ore V e i n s All  in D r i l l  Core  o r e m i n e r a l s o f t a b u l a r zones a r e p r e s e n t  in veins,  s i m i l a r l y , meta-  m o r p h i c m i n e r a l s c h a r a c t e r i s t i c o f t a b u l a r zones a r e a l s o found Some broad g e n e r a l i z a t i o n s c o n c e r n i n g o c c u r r e n c e s o f v e i n s possible.  At  (142/84NE) c o n t a i n c h a l c o -  are of large carbonate veins  i n some p o r t i o n s o f t h e w a l l  t h e r e f o r e appears  are present.  These v e i n s p i n c h and s w e l l  w h i c h have p y r i t e - c h a 1 c o p y r i t e - b o r n i t e . i s present  from > 15 t o  range from pure c h a l c o -  F i n a l l y , around DDH 128 zones o f s u l p h i d e - b e a r i n g v e i n s  It  group  t h e a r e a near t h e l o c a t i o n o f samples W73W74-W76, a s e r i e s o f v e i n s  als are quartz-carbonate,and sulphides  pyrite  This  up t o 5 p e r c e n t b o r n i t e and c h a l c o c i t e , and t h e s e m i n e r a l -  (118/65NE), which have v a r y i n g amounts o f . s u l p h i d e , o c c u r .  and d i s a p p e a r  here.  Veins are u b i t i q u o u s  through every  m e t a l l i c m i n e r a l s a r e most abundant  in veins  level  in veins.  in d r i l l  of a l l holes.  core are However  below t h e main o r e h o r i z o n s .  DDH's 88 and 110, f o r example, o r e m i n e r a l s a r e p r e s e n t  in the horizons  In  mainly  as d i s s e m i n a t i o n s , p r e s e n t as t r a c e s  127 but through t o t h e i r bottoms most o f t h e s e m i n e r a l s in w i d e l y d i s p e r s e d v e i n l e t s .  The s c a t t e r e d ore  deep i n the h o l e s g e n e r a l l y have some s t r o n g v e i n component. 116,  are  lenses  In DDH's 96 and  where the upper o r e l e n s e s a r e more s e p a r a t e d and d i s t i n c t , t h e r e i s a  s t r o n g v e i n c o n t r i b u t i o n t o the ore m i n e r a l i z a t i o n in these h o r i z o n s . f e a t u r e i s t h a t the p y r i t i c p a r t s o f DDH's 25 and 132,  have very few v e i n s .  Thus i n s t r o n g , c o n t i n u o u s ore h o r i z o n s , copper s u l p h i d e s sent as d i s s e m i n a t i o n s , w i t h l i t t l e c o n t r i b u t i o n t o t o t a l from v e i n s  until  below the main h o r i z o n s .  Another  are m a i n l y p r e -  sulphide content  P y r i t i c a r e a s have minor  s u l p h i d e c o n t r i b u t i o n from v e i n m a t e r i a l . P o s t - O r e Movement  5-3-3  in V e i n s  F a u l t i n g and j o i n t i n g commonly have a f f e c t e d p r e - e x i s t i n g v e i n s . effect  This  i s e x h i b i t e d as movement a l o n g the p l a n e o f the v e i n , and sometimes by  s m a l l - s c a l e remobi1ization of s u l p h i d e s .  Movement  is  i n d i c a t e d by s l i c k e n -  s i d i n g and s t r e t c h i n g out o f gangue m a t e r i a l and s u l p h i d e g r a i n s .  Two good  examples a r e : sample l o c a t i o n W43, where the p l a n e o f a former e p i d o t e - s u l p h i d e v e i n became the p l a n e o f a l a t e r f a u l t , and the e p i d o t e became s 1 i c k e n s i d e d , . and sample l o c a t i o n W56, where a f r a c t u r e s u r f a c e , w i t h ma 1 a c h i t e - a z u r i t e c h a 1 c o c i t e - c h a l c o p y r i t e and e p i d o t e , i s e x t e n s i v e l y s i i c k e n s i d e d . 5.3.4  T r a c e Element C h e m i s t r y o f V e i n M a t e r i a l Table 9 contains  sample o f w a l l  t r a c e elements a n a l y t i c a l d a t a o f a v e i n s e t .  rock r i g h t at the c o n t a c t o f a 3 t o 5 cm wide e p i d o t e - c a r b o n a t e -  cha1cocite-bornite-malachite vein. t a c t , and sample W89 i s  1.5  w i t h d i s t a n c e from the v e i n . prisingly,  is  W87 i s a  Sample W88 i s w a l l  m from the c o n t a c t .  nock 0.6  m from the c o n -  Z i n c , copper and ni eke ! ' d e c r e a s e  Rubidiurn' i s ' 1 owest near t h e ' v e i n ;  1  S t r o n t i urn,-^sur-  1owest n e a r ' t h e v e i n and appears' d e p l e t e d ' i n amount r e l a t i v e to  other  samples.  5.3.5  Age o f the V e i n M i n e r a l i z a t i o n Though t h e r e are some c r o s s - c u t t i n g  r e l a t i o n s h i p s p r e s e n t , a l l o f the  s u l p h i d e - r i c h v e i n s appear to have, formed penecontempouraneous1y.  The a c t u a l  TABLE IX TRACE ELEMENT ANALYSES FOR VEIN SAMPLES (ppm t p r e c i s i o n )  SAMPLE NO.  Zn  Cu_  NJ_  £L  '  '  Jit  W87  !48.49(±».15)  j7364.17(^1227.2)  46.18(10.20)  99.8( 0.57)  3.06( 0.26)  W88  93.l4(+3.54)  100.27(+2.44)  30.70(+0.19)  199.87( 0.49)  31.09(^0.06)  W89  85.75( 0.82)  98.69(+0.96)  22.72(+0.02)  199.88(10.53)  21.7( 0.07)  +  +  +  +  +  OO  129 age o f t h e s e v e i n s can o n l y be roughly a p p r o x i m a t e d . f a u l t i n g episodes  They p r e d a t e the major  as e v i d e n c e d by the s 1 i c k e n s i d i n g  but they p o s t d a t e the North Zone dyke.  This  on some s u l p h i d e  surfaces;  r e l a t i o n s h i p i s seen near the  n o r t h e r n end o f the dyke (sample l o c a t i o n W101) where p r e h n i t e - q u a r t z - e p i d o t e c a r b o n a t e v e i n s w i t h i n t e r g r o w n b o r n i t e and c h a l c o c i t e c r o s s - c u t 58).  These p a r t i c u l a r v e i n s  equivalent trends.  resemble those near DDH 16 and they a l s o  they d e f i n i t e l y c u t through the dyke. c o r r e l a t i v e w i t h the b a s i c  have  intrusives  i z e d dyke i s s i g n i f i c a n t l y younger  r o c k , but towards the  If the assumption  t h a t the dyke  Regardless,  south  is  in the H a z e l t o n Group to the s o u t h ,  formed i n post-Lower J u r a s s i c t i m e s .  ting a substantial  (fig.  At t h e i r most n o r t h e r n o c c u r r e n c e in the dyke, the v e i n s  are in the p l a n e o f the c o n t a c t between dyke and w a l l  the o r e v e i n s  the dyke  then  the m i n e r a l -  than the m i n e r a l i z e d c o n g l o m e r a t e s ,  indica-  time i n t e r v a l between f o r m a t i o n o f the v o l c a n i e l a s t i c p i l e  and the m i n e r a l i z i n g e p i s o d e .  5.4  Opaque  Mineralography  In t h i s s e c t i o n the d e t a i l e d t e x t u r a l and m i n e r a 1 o g r a p h i c opaque m i n e r a l s s t u d i e d in p o l i s h e d s e c t i o n a r e d e s c r i b e d .  f e a t u r e s o f the  These s t u d i e s  are  i m p o r t a n t because they d e f i n e a p a r a g e n e t i c sequence f o r o r e m i n e r a l i z a t i o n . 5.4.1  Magnetite Magnetite  (and l l m e n i t e ) is ubiquitous  through the e n t i r e upper member o f the Moosevale  Formation and everywhere appears p y r o g e n i c . o r i n t e r g r a n u l a r phase  It  in v o l c a n i c c l a s t s , o r as d e t r i t a l  f r a c t i o n to large c l a s t s .  grains  in a f i n e  G e n e r a l l y the c l a s t m a g n e t i t e s a r e l e s s  l a r g e r , and more e u h e d r a l than are the d e t r i t a l early  i s p r e s e n t as an i n t e r s e r t a l  ones.  altered,  The m a g n e t i t e s  in the c r y s t a l l i z a t i o n sequence o f the v o l c a n i c s as shown by  formed  grains  which appear to f o r m - n u c l e i f o r the c r y s t a l l i z a t i o n o f g l o m e r o p o r p h y r i t i c masses of a u g i t e s  in some c l a s t s .  130  Figure 58:  Prehnite-quartz-epidote-carbonate vein, with  c h a l c o c i t e and b o r n i t e , c u t t i n g the North Zone dyke.  In  t h i s f i g u r e , the dyke i s the lower p l a t e to v e i n i n g , w h i l e country  rock i s the upper p l a t e .  The t h i c k e s t v e i n i s  about  4 cm w i d e .  Figure 59:  D e t r i t a l m a g n e t i t e bed.  These m a g n e t i t e  are r e l a t i v e l y u n a l t e r e d and show o n l y s u b t l e These g r a i n s  average about  . 1 5 mm i n d i a m e t e r .  grains  rounding.  131 Rare the  detrital  grains  times ft  are  seen.  of  too small,  One  core-')  small,  2 to  grains,  in  o f one  such  hematites  sandy  0.1  t o 0.2  grains  that  average These  ween  mm.  small  in d i a m e t e r . those  in  a r e more All ning  In  grains  Cleavage,  areas  blades  of  are  more  irregular  up t o  shown by  groundmass  1.2  triangular  and  in d e t r i t a l  magnetites  have at  magnetite strong  pitting, in  photomicrograph and  are  euhedral  placer  deposits. crystals, grains'.  but  average  or  generally  twinning,  is  rare magnetite The  These  grains  a r e most  somegrains,  intergranular  disseminations  t h e same or  a  intergranular  as  f r a c t u r e d edges,  in  3000  hematite  developed  the magnetite.  are about  primary  fossil  shape)  present  in a l l  actually  both o x i d e s  appear  D e t r i t a l megnetite grains  common,  of  usually  piagioclases.  are  is  large well  (in  some-  mm i n d i a m e t e r  0.15  mm i n d i a m e t e r ,  hematite overgrow  however,  bands  probably"represent as  is  3 places  F i g . 59  Grains  generally  a magnet  w i t h minor  average  two m a i n f o r m s ;  to anhedral  the groundmass,  of  that  A s1ight ' m a r t i t i z a t i o n is  e l e c t r o n mi c r o ' s c o p e  different  has  smaller,  subhedral  felted,  grains  mm i n d i a m e t e r .  0.12  These  grains,  But  in only  the vol c a n i c 1 a s t i c s .  m a g n e t i t e bands  as  (present  magnetites.  of magnetite  of  specimen.  a t t r a c t i o n of  feature  detrital  beds  in c l a s t s  euhedral  are  of  i n hand  a slight  rare  bed w i t h m a g n e t i t e  observed.  wherein  though  portions  commonly  large  times  bands  3 cm t h i c k ,  Magnetite  The  c a n be s e e n  interesting  is  to subhedral.  and more  magnetites  bet-  o f t e n < 0.02  size  rare  mm  and shape  cases  as  rounding,  grains. least  a minor  photomicrograph  samples.  As  titanium content.  of  a-magnetite  c a n be s e e n ,  megnetite concentration,  60  and e l e m e n t a l  t i t a n i u m is rare  Fig.  is a . s c a n scans of  a' c o m p o n e n t  ilmenite grains  are  in  both.  seen,  but  f  most  i m p o r t a n t l y some  large magnetites  According  to Buddington  oxidation  of  unmixing  of  an o r i g i n a l a solid  and L i n d s l e y  have  (1964),  i1 m e n i t e - m a g n e t i t e  solution.  'exsolution l a m a l l a e of solid  lamallae this  solution,  1  of  ilmenite  type are  rather  than  due the  to  two  F i g u r e 60:  Scanning  e l e c t r o n photomicrograph o f a m a g n e t i t e in sample  8 8 E 2 w i t h e l e m e n t a l scans o f t h i s m a g n e t i t e and a n o t h e r from sample W33. Both scans i n d i c a t e a t i t a n i u m component to the m a g n e t i t e . i n W33 a l s o has a t r a c e amount o f copper.  The m a g n e t i t e  The p l a t e i s about .09 mm a c r o s s .  133 The f r e s h e s t m a g n e t i t e i s  i n a r e a s o f low s u l p h i d e c o n t e n t , but even  the most u n a l t e r e d m a g n e t i t e s have f r a c t u r e s  in them w h i c h a r e f i l l e d w i t h  c a r b o n a t e o r some o t h e r gangue. There i s a p r o g r a d a t i o n o f m a g n e t i t e t i o n seen w i t h i n c r e a s i n g s u l p h i d e c o n t e n t .  With t r a c e amounts o f  altera-  sulphide,  the m a g n e t i t e s show o n l y minor a l t e r a t i o n , however, as the s u l p h i d e c o n t e n t increases totally  the m a g n e t i t e s become s k e l e t a l  in form and u l t i m a t e l y they a r e  r e p l a c e d by gangue, l e a v i n g o n l y a pseudomorphic s k e l e t a l o u t l i n e  where s u l p h i d e s  a r e most abundant.  The s k e l e t a l m a g n e t i t e s a r e a l t e r e d m a i n l y  by sphene, w i t h e p i d o t e and c a r b o n a t e  (+quartz).  The pseudomorphed  skeletons  a r e t o t a l l y r e p l a c e d by c a r b o n a t e and sphene, and commonly a r e surrounded by w i s p y h a l o e s o f secondary h e m a t i t e . Magnetite  is  intergrown with p y r i t e , c h a l c o p y r i t e , c h a l c o c i t e , b o r n i t e ,  d i g e n i t e , c o v e l l i t e , o r secondary a f i l l i n g of cracks  hematite.  in the m a g n e t i t e g r a i n s , w i t h o n l y p y r i t e , c h a l c o c i t e and  h e m a t i t e a c t u a l l y d e v e l o p e d on m a g n e t i t e . overgrowths 5.4.2  G e n e r a l l y the s u l p h i d e s o c c u r as  on s k e l e t a l r e l i c t m a g n e t i t e  Sulphides,  e s p e c i a l l y p y r i t e , form  grains.  Chalcocite The d e s c r i p t i o n o f c h a l c o c i t e o c c u r r e n c e i s d i v i d e d i n t o two p o r t i o n s ;  chalcocite  in o r e l e n s e s , and c h a l c o c i t e in m i n e r a l i z e d v e i n s .  This  division  was made so t h a t comparison o f c h a l c o c i t e forms between t h e s e two o r e d e p o s i t types c o u l d be a c h i e v e d . 5.4.2(a) C h a l c o c i t e i n Ore Lenses C h a l c o c i t e , where p r e s e n t . i n p o l i s h e d s e c t i o n s , volume p e r c e n t .  ranged from 0.15  The most common mode.of o c c u r r e n c e o f c h a l c o c i t e , i s  serta.l i n the m a t r i x o f host v o l can i c l a s t i c r o c k s , but commonly small o f c h a l c o c i t e are d i s s e m i n a t e d occur  in l a r g e l i t h i c c l a s t s .  in s i x main forms o f the above two modes.  t i c of a l l sulphides in s e v e r a l  forms  t o 10 interamounts  Chalcocite grains  These forms a r e c h a r a c t e r i s -  and n a t i v e c o p p e r , and a s i n g l e o r e m i n e r a l can o c c u r  in a s i n g l e hand specimen.  The forms a r e d i s c u s s e d  in o r d e r  134 of decreasing  importance.  The l a r g e s t intersertal  chalcocite grains  t o sand s i z e g r a i n s  are p r e s e n t w i t h q u a r t z and c a r b o n a t e ,  o f the m a t r i x component.  This  t e x t u r e seems  t o have developed as a r e s u l t o f c e m e n t a t i o n o f a porous and permeable sand s i z e host  by p r e c i p i t a t i o n o f o r e and metamorphic m i n e r a l s  The c h a l c o c i t e g r a i n s  having t h i s  The l a r g e r g r a i n s  f o r m , but g e n e r a l l y have some s t r a i g h t edges. have  individual grains  c o c i t e which cut through normally serrate.  the e n c l o s i n g  are i r r e g u l a r  Commonly groups o f  gangue.  In o t h e r pores  smaller  (< 0.01  The second most  neighbouring  lithic clasts.  i m p o r t a n t f o r m , found  the l a r g e c h a l -  extending This  in n a t u r e and a r e spread throughout  the m a t r i x .  mm in d i a m e t e r , a v e r a g i n g  0.01  lenses.  Their size A  ( f i g . 62).  plagioclase crystals  These a r e a s a r e m a i n l y  l e n t s i z e as the w i d e l y d i s s e m i n a t e d ones, 0.1  in g a n g u e - f i 1 1 e d  in the m a t r i x ( f i n e f r a c t i o n ) .  also are  ranges  subsidiary  t y p e o f t h i s form i s found w h e r e i n the small b l e b s a r e c o n c e n t r a t e d area  from  These b l e b s  t o 0.02 mm.  blebs  form o f  in low o r e grade a r e a s and  w i t h t h e v o i d f i l l i n g s , a r e as s m a l l , d i s s e m i n a t e d b l e b s .  tral  are  mm in d i a m e t e r )  i s c h a r a c t e r i s t i c s o f the r i c h e s t s e c t i o n s o f o r e  from 0.004 t o 0.1  large c h a l -  Edges o f such g r a i n s  One l a r g e c h a l c o c i t e g r a i n had m i c r o v e i n 1 e t s  i t s main mass and c r o s s - c u t t i n g  rounded  in  If the pore i s not l a r g e , t r a i n s o f t h e s e s m a l l m i c r o v e i r i -  c o c i t e g r a i n may be c e n t r a l t o numerous,  chalcocite  61).  i n t e r c o n n e c t e d by s m a l l v e i n l e t s o f c h a l -  l e t s may spread from a c e n t r a l l a r g e r g r a i n .  of c h a l c o c i t e .  (fig.  form are up t o 2 mm in d i a m e t e r , and a v e r -  age around 0.3 t o 0.4 mm in d i a m e t e r .  cocite grains  in v o i d s  in a c e n -  pores, or  The b l e b s a r e o f  and the c o n c e n t r a t i o n areas  in  equivaare  - 0.5 mm in d i a m e t e r . In the r i c h e s t copper z o n e s ,  another t e x t u r e that is e x h i b i t e d l o c a l l y ,  i s a network o r r e t i c u l a t e t e x t u r e in which small d e t r i t u s network o f c h a l c o c i t e .  i s enmeshed  G e n e r a l l y the c h a l c o c i t e forms a l o n g g r a i n  when the d i s t a n c e between g r a i n s  is small  ( i e . on the o r d e r o f 0.01  in a  boundaries mm).  135  Figure  6l:  Straight-edged  c h a l c o c i t e g r a i n s as  i n f i n e f r a c t i o n of c o n g l o m e r a t e . grown w i t h q u a r t z . refraction  is  F i g u r e 62: f i l l e d pore. grain  The c h a l c o c i t e here  is  inter  The g r e e n i s h m a t e r i a l w i t h the h i g h e s t  lithic clasts.  This section  is about 2 mm a c r o s s  Blebs of c h a l c o c i t e c o n c e n t r a t e d In the upper  is v i s i b l e .  void-fillings  in a q u a r t z -  l e f t - h a n d c o r n e r a small  This s e c t i o n  is 2 mm a c r o s s .  magnetite  136 The.largest  networks  Although  have w i d t h s o f 0.5 mm, but average 0.1  c h a l c o c i t e i s most abundant  l a s t i c s , some does o c c u r  to 0.3 mm.  in the m a t r i x o f the v o l c a n i c -  in the l a r g e c l a s t s .  C l a s t s which c o n t a i n c h a l c o -  c i t e most commonly have a d e f i n i t e p o r p h y r i t i c t e x t u r e w i t h p l a g i o c l a s e a cryptocrysta11ine  groundmass.  C h a l c o c i t e in c l a s t s  in  i s p r e f e r e n t i a l l y in  the groundmass p a r t o f a c l a s t a d j a c e n t t o a zone o f m i n e r a l i z e d f i n e f r a c t i o n . Another form o f c h a l c o c i t e in l a r g e c l a s t s plagioclase phenocrysts. the l i t h i c c l a s t s o c c u r s as s e l v a g e s  This  i s as s m a l l  form i s p r e s e n t  contain large phenocrysts.  replacement patches  in c h a 1 c o c i t e - r i c h zones  phenocrysts.  A form found both in m a t r i x ( f i n e f r a c t i o n ) and l e s s  patches o r g r a i n s  in the c l a s t s .  These v e i n l e t s m a i n l y c r o s s - c u t  Width o f t h e s e f e a t u r e s  0.05 mm, w h i l e the l e n g t h  F i g . 6 3 is a scanning elemental  commonly  in c l a s t s ,  small  gangue  i n a m a t r i x , but a r e a l s o seen t o c u t through c l a s t s ,  even p h e n o c r y s t s averaging  where  In r a r e cases the c h a l c o c i t e  and/or complete rims t o the  i s m i c r o v e i n l e t s of c h a l c o c i t e .  i s u s u a l l y 0.1  e l e c t r o n microscope  scan o f a l a r g e c h a l c o c i t e g r a i n  shows the s m a l l e r  in  i s 0.01  to 0.1 mm,  mm but can be up t o 1 mm.  (SEM)  photomicrograph  i n t e r g r o w n w i t h gangue.  rounded b l e b - l i k e form and l a r g e  or  and F i g . 64  i n t e r s e r t a l form o f c h a l -  cocite. Chalcocite  i s commonly  o f the two i s as overgrowths  in c o n t a c t w i t h m a g n e t i t e .  The main t e x t u r e form  of c h a l c o c i t e on m a g n e t i t e o r as  r e p l a c e m e n t s o f m a g n e t i t e by c h a l c o c i t e .  irregular  Chalcocite locally f i l l s  fractures  in m a g n e t i t e but has not a c t i v e l y r e p l a c e d m a g n e t i t e . In zones o f g r e a t e s t c h a l c o c i t e c o n c e n t r a t i o n , some b o r n i t e i s p r e s e n t , most commonly  intergrown with c h a l c o c i t e .  e x h i b i t e d by t h e s e two m i n e r a l s  The v a r i e t y of  range from s i m p l e g r a i n boundary  generally textures  contacts  to  i n t r i c a t e myrmekitic intergrowths.  The m y r m e k i t i c i n t e r g r o w t h s a r e most com-  monly p r e s e n t  in the mixed s u l p h i d e a r e a .  in the l a r g e s t  grains  o f t e x t u r e i s found where one s u l p h i d e  is  This  type  in a much g r e a t e r abundance  than  137  13C3  Figure 6 3 :  Scanning e l e c t r o n p h o t o m i c r o g r a p h , w i t h e l e m e n t a l s c a n ,  of a c h a l c o c i t e grain  in sample 13C3•  The c h a l c o c i t e ( l i g h t  i s e x t e n s i v e l y i n t e r g r o w n w i t h gangue (dark g r e y ) .  The e l e m e n t a l  scan is f o r a p o r t i o n o f the c h a l c o c i t e (j_e. not w i t h gangue). plate  i s about  . 4 mm a c r o s s .  grey)  This  138  F i g u r e 64:  Scanning  blebs  and  light  grey.  section  electron  a larger chalcocite Note t h e  i s about  0.04  rounded mm  photomicrograph grain.  The  of  chalcocite  chalcocite  n a t u r e o f the b l e b s .  across.  is This  139 the o t h e r . Intergrowths  o f c h a l c o c i t e and n a t i v e copper are not common, but do o c c u r .  Most t y p i c a l l y these t e x t u r e s a r e in areas o f high n a t i v e copper c o n t e n t , w i t h s m a l l e r amounts o f c h a l c o c i t e .  Generally c h a l c o c i t e occurs  i n . c o n t a c t w i t h a much l a r g e r n a t i v e copper g r a i n . n a t i v e copper g r a i n s .  In one a r e a small  as s m a l l  Sometimes  grains  c h a l c o c i t e rims  i n c l u s i o n s of c h a l c o c i t e occurred  a l a r g e n a t i v e copper g r a i n and v i c e v e r s a .  Minute c h a l c o c i t e and n a t i v e c o p -  per b l e b s a r e sometimes c o n c e n t r a t e d in a s i n g l e gangue p a t c h , but not w i t h each o t h e r .  Age r e l a t i o n s between the two m i n e r a l s a r e v e r y  t o d e t e r m i n e but i t appears dates  in  in c o n t a c t  difficult  t h a t n a t i v e copper f o r m a t i o n very s l i g h t l y  pre-  t h a t of c h a l c o c i t e . C h a l c o c i t e and c h a l c o p y r i t e a r e never found in d i r e c t c o n t a c t .  minerals grown.  r a r e l y occur together  in a:si:ngl.e specimen and i f so a r e not  In o n l y one p l a c e was c h a l c o c i t e observed  t h i s case a m i n i s c u l e g r a i n o f p y r i t e (< 0.01 chalcocite grains Chalcocite with bornite.  is  in a strong  The two  secondary  inter-  in c o n t a c t w i t h p y r i t e .  In  mm) was growing w i t h s m a l l  hematite area.  i n t e r g r o w n e x t e n s i v e l y w i t h d i g e n i t e , even more so  C h a l c o c i t e and d i g e n i t e very commonly o c c u r t o g e t h e r ,  most c h a 1 c o c i t e - r i c h areas  have a t l e a s t a minor d i g e n i t e component.  ly-a chalcocite grain w i l l  c o n t a i n a patch o f d i g e n i t e w i t h s m a l l ,  than and Typical-  thin  (< 0.05 mm i n w i d t h ) n e e d l e s o f d i g e n i t e l a m e l l a e e x t e n d i n g from the patch i n t o the c h a l c o c i t e host ( f i g . 6 5 ) .  N e i t h e r the n e e d l e - 1 a m e l 1 a e nor the d i g -  e n i t e p a t c h need o c c u r i n the same c h a l c o c i t e g r a i n .  These l a m e l l a e can  a c c o u n t f o r up t o 50 p e r c e n t o f the c h a 1 c o c i t e - d i g e n i t e g r a i n , but a r e generally  l e s s than 10 p e r c e n t .  In o n l y one case was a m y r m e k i t i c  intergrowth  o f t h e two seen: here wavy p a t t e r n s o f a l t e r n a t i n g d i g e n i t e and c h a l c o c i t e were p r e s e n t  in a s i n g l e g r a i n  (sample W104).  The c h a 1 c o c i t e - d i g e n i t e g r a i n s  in v i e w o f the l a m e l l a e and m y r m e k i t i c t e x t u r e s , appear t o be due t o unmixing o f a former s o l i d s o l u t i o n  ( i e . they a r e penecontemporaneous).  Similar  140  F i g u r e 65:  Thin, exsolved d i g e n i t e laths  in c h a l c o c i t e .  The c h a l c o c i t e i s w h i t e and d i g e n i t e appears  as the very  t h i n b l u e l a t h s c u t t i n g through the c h a l c o c i t e mass. bornite  is  i n c o n t a c t w i t h the c h a 1 c o c i t e - d i g e n i t e  Gangue appears s e c t i o n i s 0.46  F i g u r e 66: vein.  as the brown m a t e r i a l  Pinkish  grain.  i n the p l a t e .  This  mm a c r o s s .  Typical chalcocite habit  in a quartz-carbonate  Q u a r t z and carbonate are the green background.  c h a l c o c i t e here has very w e l l minute b l u e g r a i n s covellite.  This  developed s t r a i g h t  edges.  The The  are composed o f i n t e r g r o w n d i g e n i t e and  section  i s 2 mm a c r o s s .  141 types o f e x s o l u t i o n cite-bornite solid Very contact,  rarely,  t e x t u r e s have been d e s c r i b e d by B r e t t (1964) f o r c h a l c o solutions.  in o n l y one sample, a r e c h a l c o c i t e and c o v e l l i t e found  in t h i s case  i t was a s i m p l e g r a i n boundary c o n t a c t .  Both  o c c u r t o g e t h e r commonly but i n t e r g r o w t h t e x t u r e s a r e not p r e s e n t . intergrown w i t h c h a l c o c i t e r a r e l y .  C h a l c o c i t e and g r e e n o c k i t e never o c c u r  cocite. zones  Cuprite  is  In f a c t a s u b t l e r e d d i s h t i n g e  is  present.  together.  hematite is q u i t e f r e q u e n t l y , complexly is  by the p r e s e n c e o f t h i s h e m a t i t e .  described further  minerals  The c u p r i t e i s an o x i d a t i o n o f the c h a l -  c o c i t e , and they a r e o n l y found t o g e t h e r where n a t i v e copper  Secondary  in  intergrown w i t h c h a l -  imparted t o the r i c h e s t c h a l c o c i t e  These  intergrowth textures w i l l  be  in the h e m a t i t e s e c t i o n below.  5 . 4 . 2 ( b ) C h a l c o c i t e in Veins Within veins containing sulphides, network masses. across.  These a r e q u i t e o f t e n l a r g e  Large g r a i n s ,  q u e n t l y seen  the most s i g n i f i c a n t o r e form i s  in s i z e , up t o a maximum o f 5 cm  up t o 0.5 mm a c r o s s , w i t h s t r a i g h t edges a r e a l s o  ( f i g . 66).  These s t r a i g h t - e d g e d  grains  by m i c r o v e i n 1 e t s o f s u l p h i d e s .  Smaller  grains  the v e i n gangue.  are disseminated  through  (< 0.1  rock to one o f t h e s e v e i n s  interconnected  mm in d i a m e t e r ) , b l e b - l i k e  i s o b s e r v e d , the s u l p h i d e s  g e n e r a l l y found t o extend i n t o the h o s t , m a i n l y as d i s s e m i n a t i o n s irregular grains,  o r as s m a l l  B o r n i t e appears in these v e i n s . growths  fre-  l o c a l l y o c c u r at the  c o n t a c t between q u a r t z and c a r b o n a t e gangue and g e n e r a l l y a r e  When t h e host  as  are  of small  microveinlets.  to e q u a l , o r s l i g h t l y  T y p i c a l textures present  s u r p a s s , the amount o f c h a l c o c i t e in the v e i n s a r e ; m y r m e k i t i c  inter-  o f b o r n i t e and c h a l c o c i t e , and p a t c h e s and n e e d l e - l i k e l a m e l l a e o f  d i g e n i t e and c h a l c o c i t e .  C o v e l l i t e is  less  commonly seen w i t h c h a l c o c i t e ,  and m a l a c h i t e i s p r e s e n t as a l t e r a t i o n h a l o e s around some c h a l c o c i t e  grains.  142 5-4.3  Bornite  5.4.3(a)  Bornite  The much  r a t i o of  t h e same as  edged of  grains,  bornite  tive  a pink  colour  locally  is  Some o f  this  very  ment m i n e r a l  nite cut  at  many  colours common and  through  type having intergrowths bornite  chalcocite contains  has  a myrmekitic present  these g r a i n s .  have  covellite  digenite  If  the d i g e n i t e  the b o r n i t e host  The  second  bornite  the case  of  straight, Bornite  II  replacing  type  the  t y p e has  is  (fig..6'8).  mm l o n g .  the d i g e n i t e  This  This  which occur  replacement  (1964,  p.1244)  c a n be d i v i d e d  into  along  Rarely,  phase  where  common  replacebe  thin  Very  fractures  large  bor-  which  large,  microvein1ets  of  mass. by  regular  coherent  when " t h e r e of  host  lamallae exists.as within  t h e m a j o r one  exsol-  approximately  t e x t u r e appears  w e l l - d e f i n e d planes  two s u b g r o u p s ;  Chalcocite  a r e a becomes  occurs  Also  a l t e r a t i o n may  lamallae are  exsolution  ( f i g . 67) .  except  a very  distinguished  These  the c h a l c o p y r i t e along  bornite.  has  bornite  textures  in a g r a i n .  and s e l v a g e s  is  distinc-  pink  d i g e n i t e may f o r m a  i n t e r f a c e between e x s o l v i n g  bornites,  also  the d i g e n i t e .  II)  types  lamallae digenite.  from the main d i g e n i t e  (bornite  d e f i n e d by B r e t t  these  laths  occur  chalcoyrite  0 . 0 0 2 mm w i d e and 0 . 0 4  rims  two m a i n  sulphides.  lamallae.  exsolved  areas,  are  in c h a l c o c i t e - r i c h areas  Digenite  In o t h e r  invade  across  are  i n t h e same b o r n i t e g r a i n  Most o f t e n  digenite  continuity  straight-  many  specific  b e t w e e n c h a l c o c i t e and b o r n i t e  the g r a i n .  w h i c h as  as  Each  texture with this  bornites.  these  of  nature,  forms  chal coci te, of ten times w i t h myrmekitic  of  lamallae of  I)  chalcopyrite exsolution  rosettes  ution  with other  Bornite  There  two s u b g r o u p s .  (bornite  from c h a l c o c i t e .  commonly  60:40.  grains.  disseminated  exsolved  the contact  around  small  type of  lacks  is  there aren't  and  intergrown  with  grains  .  c h a l c o c i t e , except  d i g e n i t e a r e not  has  intergrown  of  w i t h one  digenite  primary  wedge  as  intergrown  rarely  digenite  those  nor  textures,  Lenses  c h a l c o c i t e to b o r n i t e  present  T h e most  and  i n Ore  is  in  lattice  phase".  In  regular,  the host having  bornite.  a yellow-  143  F i g u r e 67: bornite.  Myrmekitic  The b o r n i t e is  the background This s e c t i o n  F i g u r e 68: supergene  l i g h t pink  in this p l a t e .  i n c o l o u r and  forms  The c h a l c o c i t e i s w h i t e .  i s 2 mm a c r o s s .  Bornite with exsolved c h a l c o p y r i t e laths development of d i g e n i t e .  p i n k and the d i g e n i t e best seen  intergrowth of c h a l c o c i t e in  in d i g e n i t e .  is l i g h t b l u e .  The b o r n i t e i s  yellowish-  Chalcopyrite laths  This  are  The d i g e n i t e was produced by o x i d a t i o n  of b o r n i t e . Dark blue patches a r e c o v e l l i t e w h i c h has digenite.  and  s e c t i o n i s 0.46 mm a c r o s s .  replaced  144 ish-pink  c o l o u r and u s u a l l y  up t o 8 volume p e r c e n t c h a l c o p y r i t e  (bornite  l l a ) , the secondary  group are y e l l o w e r  than 8 p e r c e n t c h a l c o p y r i t e l a m a l l a e ( b o r n i t e sent  l o c a l l y as s i m p l e g r a i n s  these groups Grains  is found  in c o l o u r and can have  lib).  Chalcopyrite  in c o n t a c t w i t h b o r n i t e g r a i n s .  of b o r n i t e  i n t e r g r o w n w i t h the d i g e n i t e .  as patches  in grains.  g r a i n s where the b o r n i t e has been t o t a l l y r e p l a c e d ( f i g .  rounded b l e b s o r l a r g e r  the s t a g e o f noncoherence  as  In  c o h e r e n t e x s o l u t i o n y i e l d s almost m y r m e k i t i c Usually  digenite exsolves  tion  is that  in b o r n i t e  68).  in b o r n i t e  (ie.  reached  i t s most i n t e n s e form t h i s intergrowths  in the host b o r n i t e .  non-  o f b o r n i t e and c h a l Very  w i t h some o f these b l a d e s and forms complete rims  in b o r n i t e has  the  in p l a c e s  i t i s e x h i b i t e d by f a t t e r b l a d e - l i k e l a m a l l a e .  the c h a l c o p y r i t e b l a d e s  the  has gone t o the stage where c h a l -  i r r e g u l a r blades  in f i g . 69).  are  replacing bornite, c o v e l l i t e  (+ c o v e l l i t e ) patches  l l b chalcopyrite exsolution  takes  Where  Replacement may be so e x t e n s i v e  c h a l c o p y r i t e l a m a l l a e a r e seen in d i g e n i t e  copyrite.  pre-  N e i t h e r of  The d i g e n i t e g e n e r a l l y  o r s e l v a g e s on f r a c t u r e s  i s p a r t i c u l a r l y abundant  c o p y r i t e forms  is a l s o  l l a t h a t l o c a l l y c o n t a i n no c h a l c o p y r i t e l a m a l l a e ,  form o f rims around g r a i n s ,  In b o r n i t e  greater  in c o n t a c t w i t h c h a l c o c i t e . .  in many c a s e s p a r t l y r e p l a c e d by d i g e n i t e .  digenite  lamallae  (Cha1 c o p y r i t e - d i g e n i t e  been d e s c r i b e d by Morimoto e_t a_l_. (1959)) •  These  rarely  around exsolubornites  a r e s t r o n g 1 y rep 1aced by d i g e n i t e and c o v e l l i t e , which m a i n l y o c c u r as  irregu-  l a r patches.  other  C o v e l l i t e is b e t t e r developed  type and f r e q u e n t l y o c c u r s No b o r n i t e  i s found  a f t e r these b o r n i t e s  in c o n t a c t , o r even  p y r i t e , n a t i v e copper or g r e e n o c k i t e . and i s 5.4.3(b)  commonly Bornite  Relationships  in b o r n i t e  ( l i b ) without  digenite.  in the same g e n e r a l  Bornite  l o c a l e , as  l o c a l l y has overgrown  i n t i m a t e l y i n t e r g r o w n w i t h secondary in  l l b than in any  magnetite  hematite.  Veins o f b o r n i t e and o t h e r s u l p h i d e s  those seen i n the o r e l e n s e s -  in v e i n s  are comparable  The t h r e e types o f b o r n i t e are present  in  to veins.  145  F i g u r e 69: bornite occurs  Noncoherent  llb.  e x s o l u t i o n of c h a l c o p y r i t e  The b o r n i t e  is p i n k i s h .  The  chalcopyrite  as rounded b l e b s w i t h i n the b o r n i t e mass.  and minor c o v e l l i t e (blue c o l o u r ) fractures oxidation.  in Digenite  o c c u r as s e l v a g e s on  c u t t i n g the b o r n i t e mass, due to supergene This s e c t i o n  is  1 mm a c r o s s .  146 Bornite  I has no c h a l c o p y r i t e l a m a l l a e and i s the o n l y b o r n i t e type i n t e r -  grown w i t h c h a l c o c i t e .  The b o r n i t e l l a and l l b a r e a l s o p r e s e n t .  massive b o r n i t e Mb g r a i n s , are well developed. fractures selvages 5.4.4  the d i g e n i t e envelopes  In some  to c h a l c o p y r i t e l a m a l l a e  D i g e n i t e a l s o o c c u r s commonly as rims and s e l v a g e s  in t h e s e l a r g e b o r n i t e s  lib.  on  C o v e l l i t e i s p r e s e n t as rims and  on f r a c t u r e s where d i g e n i t e i s not  present.  N a t i v e Copper N a t i v e copper i s b e s t developed as network masses i n the m a t r i x o f the  host v o l c a n i c l a s t i c s .  These networks a r e up t o 0.5  o c c u r s as v o i d f i l l ins and/or small d i s s e m i n a t e d common t e x t u r e i s as minute g r a i n s phenocrysts  of large c l a s t s .  times rims and e n c l o s e s entire clasts. 0.01  t o 1 cm w i d e .  (< 0.01  ("dust") disseminated  Copper  mm) g r a i n s .  Another  in a l t e r e d f e l d s p a r  If t h e r e i s a l a r g e amount o f c o p p e r ,  phenocrysts,  also  replaces phenocrysts  i t some-  and even surrounds  S e r r a t e edges a r e found on the i n t e r m e d i a t e s i z e d g r a i n s . ( i e .  t o 0.02 mm). Copper g r a i n s  grain.  g e n e r a l l y have c u p r i t e rims c o m p l e t e l y s u r r o u n d i n g  the  F i g . 70 i s a s c a n n i n g e l e c t r o n m i c r o s c o p e p h o t o m i c r o g r a p h o f one such  g r a i n and r i m .  A s i d e from the c u p r i t e , n a t i v e copper i s o n l y found i n c o n t a c t  with chalcocite.  D i g e n i t e and/or c o v e l l i t e may be p r e s e n t  t i o n as n a t i v e copper but n a t i v e copper i s nowhere  in the same s e c -  in c o n t a c t w i t h these s u l -  phides. N a t i v e copper  is  r a r e i n . v e i n s and i s o n l y seen  pyrite, chalcopyrite or greenockite.  in t h o s e w i t h no b o r n i t e ,  C u p r i t i c rims t o n a t i v e copper a r e com-  mon in v e i n s . 5.4.5  Chalcopyrite C h a l c o p y r i t e m i n e r a l i z a t i o n is present  in t h r e e main s e t t i n g s .  n o t a b l e o c c u r r e n c e i s where o t h e r copper s u l p h i d e s a r e p r e s e n t . chalcopyrite  i s a minor phase o c c u r r i n g as t h i n l a t h s  c h a l c o p y r i t e may a l s o be p r e s e n t  in these areas as  in b o r n i t e .  The most  In t h i s  case  However  l a r g e r masses having mutual  F i g u r e 70:  N a t i v e copper g r a i n w i t h c u p r i t e r i m .  The n a t i v e copper i s the l i g h t grey m a t e r i a l i n the c e n t r e o f the mass and c u p r i t e i s the s l i g h t l y grey  rim.  about O.kS  This  scanning  mm a c r o s s .  darker  e l e c t r o n photomicrograph  is  grain  boundaries  with bornite.  Small  blebs of c h a l c o p y r i t e are u s u a l l y Chalcopyrite  is a l s o  two l a t t e r m i n e r a l s  (< 0.01  t o 0.1  s c a t t e r e d through  is  meter a r e  the groundmasses t o o .  i n t e r g r o w n w i t h d i g e n i t e and/or c o v e l l i t e , where have r e p l a c e d  the dominant  sulphide.  in these zones.  The l a r g e s t  is the case where  grains,  chalco-  up t o 0.5 mm i n d i a -  The major t e x t u r e f o r c h a l c o p y r i t e here  i s as  network masses in sand s i z e m a t r i x o f v o l c a n i c l a s t i c c o n g l o m e r a t e s . p y r i t e a l s o occurs in large c l a s t s crysts,  as  local  (fig. 71), microveinlets  in a q u a r t z amygdule  c h a l c o p y r i t e - r i c h zones, in such zones.  grains.  ( f i g . 72).  Greenockite occurs  chalcopyrite grains.  cross-cutting  clasts  large  Chalco-  phenocrysts  or t h e i r  pheno-  In one case c h a l c o p y r i t e was  C h a l c o c i t e is nowhere p r e s e n t  and d i g e n i t e and c o v e l l i t e a r e o n l y  has a mutual g r a i n boundary  one  v o i d f i l l i n g s , masses i n and around  and as s m a l l e r d i s s e m i n a t e d  observed  these  bornite.  The second type o f c h a l c o p y r i t e o c c u r r e n c e pyrite  148 shaped  mm) i r r e g u l a r  sporadically  rarely  in  present  in cha1 c o p y r i t e - r i c h zones and  texture with chalcopyrite.  L i m o n i t e commonly  P y r i t e was seen i n c o n t a c t w i t h c h a l c o p y r i t e  rims  in o n l y  example. The f i n a l  type o f c h a l c o p y r i t e m i n e r a l i z a t i o n i s as r a r e minute  w i t h i n p y r i t i c zones. separated grains. 5.4.6  The c h a l c o p y r i t e  i s p r e s e n t as s m a l l , < 0.01  D i r e c t c o n t a c t w i t h p y r i t e is  mm, w i d e l y  rare.  Pyrite Amount o f p y r i t e in the p o l i s h e d s e c t i o n s  small  grains  t r a c e t o over 25 volume p e r c e n t .  Most commonly p y r i t e o c c u r s d i a m e t e r but a v e r a g i n g  0.1  as  s t u d i e d , v a r i e d from a very  The p y r i t e o c c u r s  i r r e g u l a r l y shaped g r a i n s ,  in s e v e r a l  up t o 0.6 mm in  t o 0.2 mm, i n t e r s e r t a l t o sand s i z e m a t r i x  These p y r i t e g r a i n s t y p i c a l l y form net or mesh t e x t u r e s where p y r i t e abundant.  S m a l l e r < 0.01  t y p i c a l l y disseminated  mm in d i a m e t e r ,  through  rounded b l e b s of p y r i t e a r e  the m a t r i x o f v o l c a n i c l a s t i c  These b l e b s a r e the t y p i c a l form o f p y r i t e in i t s areas o f  forms.  grains. is also  conglomerates. low c o n c e n t r a t i o n .  149  F i g u r e Jl: material  C h a l c o p y r i t e o c c u r r i n g as  intra-phenocryst  i n the groundmass of a l i t h i c c l a s t .  The  s i l i c a t e p h e n o c r y s t s a r e the r e f r a c t i v e brownish  grains.  This s e c t i o n i s about 2 mm a c r o s s .  F i g u r e 72:  C h a l c o p y r i t e in a q u a r t z amygdule.  i s 4 mm a c r o s s .  Section  • P y r i t e occurs  150  in c l a s t s , t o o , where i t r e p l a c e s the groundmass o r  cross-cuts  phenocrysts. Textures  i n d i c a t e t h a t the p y r i t e i s  in l a r g e p a r t superimposed upon the  host v o l c a n i c l a s t i c rocks as are copper s u l p h i d e s . of p y r i t e are present  However very r a r e l y cubes  in l i t h i c c l a s t s , and may r e p r e s e n t an  of p y r i t e m i n e r a l i z a t i o n .  But, no p y r i t e i s found as cubes  e a r l i e r stage in l a r g e  clasts  except where t h e r e i s o t h e r e v i d e n c e o f a superimposed m i n e r a l i z i n g e v e n t . Thus, i t seems u n l i k e l y t h a t much, i f any, p y r i t e p r e d a t e s the main m i n e r a l i z i n g e p i s o d e t h a t i n c l u d e s copper  sulphides.  When p y r i t e e x h i b i t s s t r o n g net t e x t u r e s w r a p p i n g around and between matrix grains,  broad d i f f u s e l i m o n i t i c h a l o e s a r e o f t e n developed through  remainder o f the host areas o f  rock.  DDH 25, which almost  intense l i m o n i t i c a l t e r a t i o n .  is t o t a l l y p y r i t i c ,  contains  P y r i t e is g e n e r a l l y a s o l i t a r y s u l -  phide in r a r e c o n t a c t w i t h o n l y c h a l c o p y r i t e . Rare t r a c e s of p y r i t e o c c u r the same a r e a s as c h a l c o p y r i t e , b o r n i t e o r g r e e n o c k i t e ,  a f t e r magnetite.  in  but s t r o n g c o n c e n -  t r a t i o n s o f p y r i t e g e n e r a l l y a r e d e v o i d o f copper m i n e r a l s . r e p l a c e d margins o f m a g n e t i t e g r a i n s ,  the  P y r i t e may have  or have overgrown gangue  pseudomorphic  Genera 11y where in c o n t a c t w i t h m a g n e t i t e , p y r i t e  fills  f r a c t u r e s o r has g r a i n boundary c o n t a c t s w i t h the o u t e r margins o f the magnet i t e gra i ns . Pyrite  is  r a r e in v e i n s .  to o t h e r s u l p h i d e s  Where p r e s e n t , the p y r i t e i s very  and i s not in c o n t a c t w i t h them.  subsidiary  L o c a l l y v e i n s are pure  pyrite. 5.4.7  Digenite Digenite's  cocite,  most common o c c u r r e n c e s a r e , a g a i n , as e x s o l u t i o n w i t h c h a l -  r e p l a c e m e n t s o f b o r n i t e , and minor e x s o l u t i o n w i t h b o r n i t e .  is a l s o p r e s e n t t o a minor e x t e n t as s m a l l seminations  in c h a 1 c o c i t e - b o r n i t e a r e a s .  w i t h the d i g e n i t e in these g r a i n s . .  (< 0.01  Digenite  t o 0.1 mm), s o l i t a r y  C o v e l l i t e i s sometimes  dis-  intergrown  C o v e l l i t e i s p r e s e n t as r o s e t t e s  replacing  151 some d i g e n i t e masses. ore  Digenite occurs  in v e i n s  in the same manner as  in the  lenses. C o v e l 1 i te  5-4.8  The dominant a s s o c i a t i o n s  o f c o v e l l i t e a r e d e s c r i b e d above.  i s a l s o p r e s e n t as minor d i s s e m i n a t e d , s o l i t a r y g r a i n s . a r e c o r r o d e d and rimmed by c u p r i t i c a l t e r a t i o n . lenses 5.4.9  Covellite  Sometimes  these  C o v e l l i t e in v e i n s  and o r e  i s the same. M a l a c h i t e and A z u r i t e  M a l a c h i t e , and much s m a l l e r amounts o f a z u r i t e , a r e formed as a a l t e r a t i o n of the main copper m i n e r a l s . f u s e h a l o e s around g r a i n s ore  grains  T y p i c a l l y these c a r b o n a t e s  o f copper s u l p h i d e .  later form d i f -  Both are found on v e i n s  and  lenses.  5-4.10 C u p r i t e and L i m o n i t e Cuprite  i s p r e s e n t as o x i d a t i o n rims on n a t i v e copper g r a i n s ,  w i t h c h a l c o c i t e and c o v e l l i t e .  and r a r e l y  L i m o n i t e rims c h a l c o p y r i t e and forms  diffuse  a l t e r a t i o n h a l o e s around p y r i t i c a r e a s . 5-4.11 Greenock i te Greenockite the S u s t u t sample.  i s by f a r the r a r e s t  deposit.  Its  presence  Its is  in d i a m e t e r , which o c c u r  s u l p h i d e o f those so f a r  amount nowhere exceeds 2 volume p e r c e n t o f a g i v e n i n d i c a t e d by b r i g h t o r a n g e - y e l l o w s p o t s , in some c o r e .  CdS around the main g r e e n o c k i t e g r a i n . p a t c h e s up to 0.2 'nal  i d e n t i f i e d in  mm in d i a m e t e r .  of  1 t o 2 mm  Thi.s c o l o u r a t i o n i s a d i f f u s e h a l o o f The g r e e n o c k i t e g r a i n s  These g r a i n s  are  irregular  have i n t e n s e y e l l o w i s h  r e f l e c t i o n and a r e y e l l o w i s h under c r o s s e d n i c h o l s .  F i g . 73 i s a  interscanning  e l e c t r o n m i c r o s c o p e photomicrograph and e l e m e n t a l scan o f a g r e e n o c k i t e g r a i n . No s p h a l e r i t e nor g a l e n a have been i d e n t i f i e d w i t h the g r e e n o c k i t e , o r o t h e r a r e a s o f the d e p o s i t . z i n c present  But the e l e m e n t a l scan shows t h e r e i s a  in the g r e e n o c k i t e g r a i n .  p y r i t e zones o f o r e l e n s e s , and o n l y  G r e e n o c k i t e is found o n l y  in c o n t a c t w i t h c h a l c o p y r i t e .  in any little  in c h a l c o Minor  pyr-  96D4  F i g u r e 73:  Scanning e l e c t r o n photomicrograph and e l e m e n t a l scan  of a greenockite.  Note the minor z i n c component.  i s about O.kh mm a c r o s s .  This  section  153 r i t e may be p r e s e n t contact.  in a g i v e n a r e a w i t h g r e e n o c k i t e but the two are not  No o t h e r s u l p h i d e  in  i s found a s s o c i a t e d w i t h g r e e n o c k i t e .  Only one example of g r e e n o c k i t e in a v e i n has been seen by the a u t h o r . At sample l o c a t i o n WI 15 t r a c e s o f g r e e n o c k i t e o c c u r in a < 5 mm t h i c k , c a r b o n ate-rich vein. 5.4.12 Hemati t e There a r e two g e n e r a t i o n s generation Hematite  of h e m a t i t e in the S u s t u t r o c k s .  i s p y r o g e n i c h e m a t i t e ( h e m a t i t e I)  t e x t u r e s as o u t l i n e d above f o r m a g n e t i t e .  a l s o p r e s e n t as d e t r i t a l  first  formed w i t h the v o l c a n i c c l a s t s .  I i s much l e s s abundant than the p y r o g e n i c m a g n e t i t e .  has the same g e n e r a l  The  grains with magnetite ( f i g . 5 9 ' ) .  This hematite Hematite I  is  The p r i m a r y hema-  t i t e has not s u f f e r e d as much a l t e r a t i o n and replacement as the m a g n e t i t e s and thus i s g e n e r a l l y p r e s e n t as more o r l e s s e u h e d r a l The second g e n e r a t i o n of h e m a t i t e ( h e m a t i t e II) and dominant  in amount.  copper and copper s u l p h i d e c o r e and i s  scale.  trails, fuse,  H e m a t i t e II  H e m a t i t e II  i s u b i q u i t o u s through  i n t i m a t e l y i n t e r g r o w n w i t h the c o p p e r -  o c c u r s as minute s p i k e s ,  needles,  c i r c l e s , r i m s , e t c . ( f i g . .74).  These c h a i n s , e t c . , have broad,  red i n t e r n a l l y r e f l e c t i n g h a l o e s about them.  H e m a t i t e II  mm in d i a m e t e r ) b l e b s w h i c h g e n e r a l l y a r e  through the m a t r i x o f copper s u l p h i d e  as network masses, do not have any a s s o c i a t e d h e m a t i t e II. ated s u l p h i d e g r a i n s ,  dif-  is a l s o p r e disseminated  i n t e r s e r t a 1 1 y and Smaller  dissemin-  however, are g e n e r a l l y rimmed and surrounded by the  Commonly these h e m a t i t e II  intergrown w i t h w e l l  rings,  zones.  The l a r g e r g r a i n s o f c h a l c o c i t e and b o r n i t e , o c c u r r i n g  hematite chains.  l a t h s and  (< 0.004 mm i n s i z e ) which form i n t e r c o n n e c t e d c h a i n s ,  sent as minute (< 0.01  native  has developed s p e c t a c u l a r forms on a m i c r o s c o p i c  In g e n e r a l , h e m a t i t e II  i r r e g u l a r masses  i s the more important  T h i s h e m a t i t e formed a t the same time t h a t p y r i t e  and copper s u l p h i d e s were d e v e l o p e d .  rich sulphides.  grains.  c h a i n s and the s u l p h i d e s  d e f i n e d , d i s c r e t e h e m a t i t e II  l a t h s which are as  are large  154  F i g u r e 74:  Photomicrograph o f w i s p y c h a i n s and t r a i l s  o f h e m a t i t e II. the h e m a t i t e .  There i s a s l i g h t  r e d d i s h h a l o around  The l a r g e r w h i t e g r a i n s  w i t h minor h e m a t i t e .  are mainly c h a l c o c i t e  T h i s s e c t i o n i s 0.46 mm a c r o s s .  as 0.01  by 0.04  mm.  These  aneous c r y s t a l l i z a t i o n . cite  155 contempor-  i n t e r g r o w t h s seem to be i n d i c a t i v e o f  The common i n t e r g r o w t h o f h e m a t i t e II  and c h a l c o -  i s shown in f i g . 15 as a s e r i e s o f s c a n n i n g e l e c t r o n m i c r o s c o p e  micrographs  photo-  showing a c h a l c o c i t e - h e m a t i t e a r e a and two ion d i s p e r s i o n  o f copper _vs_. i r o n w i t h i n the a r e a . and r e p l a c e d by t h i s h e m a t i t e on Hematite  II  M a g n e t i t e may be p a r t i a l l y overgrown  margins.  i s the reason f o r the g e n e r a l  r i c h e s t copper a r e a s .  Hematite II  plates  also occurs  o f l a r g e c l a s t s w i t h i n the o r e zones.  r e d d i s h t i n g e found in p l a g i o c l a s e  It appears  in the  phenocrysts  t h a t h e m a t i t e II  is  possi-  b l y d e r i v e d by a l t e r a t i o n of p y r o g e n i c m a g n e t i t e and p r i m a r y s i l i c a t e s . The h e m a t i t e II  i s not  5.4.13 C o n c l u s i o n s N a t i v e copper extensively present.  intergrown w i t h p y r i t e or c h a l c o p y r i t e .  on Opaque M i n e r a l Assemblages i s found w i t h c h a l c o c i t e o n l y .  i n t e r g r o w n and in t h e i r g e n e r a l  C h a l c o c i t e and b o r n i t e a r e  areas d i g e n i t e and c o v e l l i t e a r e  C h a l c o c i t e does not o c c u r w i t h a l l b o r n i t e a r e a s , e s p e c i a l l y the  b o r n i t e w i t h e x s o l v e d c h a l c o p y r i t e , w h i c h i s never found w i t h c h a l c o c i t e . Minor c h a l c o p y r i t e i s found i n mos t b o r n i t e a r e a s , but not w i t h b o r n i t e Where c h a l c o p y r i t e i s abundant ockite.  i t is  p y r i t e - r i c h zones.  in c h a l c o -  have overgrown p y r o g e n i c m a g n e t i t e s .  F i n a l l y hema-  i s c l o s e l y a s s o c i a t e d and i n t e r g r o w n w i t h c h a l c o c i t e , b o r n i t e  d i g e n i t e , and/or  5-5  G r e e n o c k i t e i s found o n l y  Chalcocite, bornite, digenite, covellite, chalcopyrite,  p y r i t e , and h e m a t i t e II II  intergrown e x t e n s i v e l y only with green-  P y r i t e i s very r a r e l y in c o n t a c t w i t h c h a l c o p y r i t e , and g e n e r a l l y  t h e s e two s u l p h i d e s o c c u r s e p e r a t e l y .  tite  I.  covellite.  Ana 1yses o f  Intergrowth and Replacement T e x t u r e s  As d e s c r i b e d in the f o r e g o i n g m i n e r a l o g r a p h i c s e c t i o n s different  types of  be d i s c u s s e d  I,  i n t e r g r o w t h and replacement t e x t u r e s .  i n d i v i d u a l l y and e v a l u a t e d in terms  there are several These t e x t u r e s  of t h e i r possible  will  r e l a t i o n to  156  F i g u r e 75:  Ion d i s p e r s i o n  p l a t e s of copper and  within a chalcocite-hematite 75a: following material  II  intergrowth  T h i s p l a t e shows the area where  two p l a t e s were t a k e n .  The l i g h t  is c h a l c o c i t e and h e m a t i t e .  mm a c r o s s .  iron  area. the grey  A l l plates  are  0.46  Fe igure 7 5 b :  These  two p l a t e s are d i s p e r s i o n  o r copper and i r o n r e s p e c t i v e l y .  analyses  They show the  intense  ntergrowths o f c o p p e r , as c h a l c o c i t e , and i r o n , as hemat i t e .  ore  158  genesis.  5-5-1  Chalcocite-Digenite Buerger  (1941) found t h a t c h a l c o c i t e (Cu S) was t r a n s f o r m e d t o d i g e n i t e 2  (Cu^S^) upon h e a t i n g  in d i r e c t c o n t a c t w i t h a i r , due t o 0^ atoms being  taken  i n t o the c h a l c o c i t e l a t t i c e s t r u c t u r e , t h u s , e f f e c t i v e l y d e c r e a s i n g Cu c o n t e n t r e l a t i v e to the a n i o n s .  Some o f the samples  here were prepared by h e a t i n g  t h e sample and a p l a s t i c b r i q u e t f o r 5 minutes  a t 150*C u n t i l  the briquet  melted t o form a c a s i n g  f o r t h e sample.  growths  c o u l d c o n c e i v a b l y be due t o t h i s h e a t i n g .  in thse samples  textural  Thus some d i g e n i t e - c h a 1 c o c i t e  inter-  However  s t u d i e s d e s c r i b e d f o r . t h i s m i n e r a l p a i r were c o n f i n e d t o those  p l e s which were not heated d u r i n g p r e p a r a t i o n o f p o l i s h e d s e c t i o n s .  sam-  There-  f o r e t h e i r t e x t u r e s can be accepted as being r e p r e s e n t a t i v e o f o r e i n p l a c e . Craig  (1974) s t a t e s  t h a t d i g e n i t e has a complete s o l i d s o l u t i o n w i t h  c h a l c o c i t e a t temperatures above ^ 9 3 ' C ility  Roseboom (1966) s u b d i v i d e d the s t a b -  f i e l d s o f t h e phase diagram ( f i g . 76) i n t o d j u r l e i t e - c h a l c o c i t e and  d j u r 1 e i t e - d i g e n i t e assemblages.  D i g e n i t e - c h a 1 c o c i t e assemblages a r e thus  d e f i n e d as not e x i s t i n g a t room t e m p e r a t u r e . by t h e author  i n any o f the Sustut  samples,  D j u r l e i t e was not i d e n t i f i e d however d e f i n i t e r e c o g n i t i o n o f  d j u r l e i t e v s . c h a l c o c i t e can be a c h i e v e d o n l y by X - r a y d i f f r a c t i o n and even then the d i f f r a c t i o n p a t t e r n s o f the t w o . m i n e r a l s a r e very s i m i l a r .  Identi-  f i c a t i o n o f d j u r l e i t e o r c h a l c o c i t e w i t h the r e f l e c t e d l i g h t microscope i m p o s s i b l e as both m i n e r a l s have s i m i l a r c h a r a c t e r i s t i c s Cook leite.  (1972) s p e c u l a t e s  1962).  t h a t most n a t u r a l c h a l c o c i t e s a r e a c t u a l l y d j u r -  For t h e purpose o f t h i s t h e s i s a l l copper m i n e r a l s o o m p o s i t i o n a l l y b e -  tween Cu^  and Cu^  in the Sustut c i t e " . . present It  (Roseboom,  is  a r e r e f e r r e d t o as c h a l c o c i t e . D j u r l e i t e i s u n d o u b t l y  d e p o s i t but in unknown amounts.  It i s l i k e l y t o be the " c h a l c o -  in t h e s t a b l e p a i r o f d i g e n i t e - c h a 1 c o c i t e .  i s assumed t h a t d i g e n i t e - c h a 1 c o c i t e  from a s o l i d s o l u t i o n formed above 9 3 ' C .  present  intergrowths  represent  unmixing  159  1  Cu S x  X=  F i g u r e 76: Roseboom,  ', 'i '' 1.70  'i  'i •' •' V i I I 1.60  I  I  I  ;' .' i 'i  '| I  1.90  i  1  i'  i'  i I  I  I'I \ l .'| 'i l i 1 . 'i •  2.0C  Phase diagram f o r the Cu-S system 1966,  p. 648).  '2.10  (from  As can be s e e n , below 93* C  d j u r l e i t e e n t e r s any s o l i d s o l u t i o n o f c h a l c o c i t e and d i g e n i t e as a phase, and t h e r e f o r e c h a 1 c o c i t e - d i g e n i t e i n t e r g r o w t h s are m e t a s t a b l e a t room t e m p e r a t u r e .  160 5-5-2  C h a 1 c o c i t e - B o r n i t e and  The  myrmekitic  bornite  intergrowths  intergrowths  high-temperature phases on  probably  side"  i s 200"C  illustrates  F i g . 77 from B r e t t (1963, p. 194) At Sustut,  intergrowths  (as shown by the "steepness 195).  Similarly,  the m i s c i b i l i t y  intergrowths  indicate  (Brett,  ved were h i g h , as  5-5-3  gap  1962)  along  that  can accommodate s u b s t a n t i a l or amounts o f metal  the d i g e n i t e - b o r n i t e j o i n .  initial  mole percent  In Sustut  digenite, indicating  These v e r m i c u l a r  intergrowths  c o n c e n t r a t i o n s o f both  phases  K u l l e r u d (1961), b o r n i t e at high  variations  to s u l p h u r .  Cu^FeS^ and  s o l u t i o n s are present on  in the amounts o f  With d e c r e a s i n g  in the process  the Sustut  Two  iron  temperature,  rearrangement c l o s e r  ents a r e e x s o l v e d as s e p a r a t e phases.  composition  temperatures to copper such  to the  high-tem-  the n o n - s t o i c h i o m e t r i c compon-  different  parental bornite s o l i d  p r o p e r t y : b o r n i t e I c o n t a i n s excess  Cu  b) c o n t a i n  Fe as c r y s t a l .jographi c a l 1 y. o r i ented-1 aths .-of c h a l c o p y r i t e .  F i g . 79.  (from Brett', 1963,  solution miscibility exsolved cates,  and/  stoichio-  S in the form of c h a l c o c i t e and/or d i g e n i t e ; b o r n i t e II (a and  excess  invol-  (+Digenite)  p e r a t u r e b o r n i t e undergoes ,a l a t t i c e  and  the b o r n i t e  member.  to Morimoto and  m e t r i c composition  o f the s o l v u s on  solid  f i g . 78, a l s o from B r e t t (1963, p.193),  range from 20 to 50  Chalcopyrite-Born?te  According  are about 50:50,  l a m a l l e r e x s o l u t i o n i s more common where bulk  i s c l o s e to an end  shows  Thus, a minimum temperature of f o r m a t i o n o f t h i s  a minimum temperature of f o r m a t i o n of 250'C. also  the r a r e r d i g e n i t e -  a r e formed by unmixing of a p r e - e x i s t i n g s i n g l e ,  the Cu^S-Cu^FeS^ j o i n .  ( i b i d . , p.  examples,  of c h a l c o c i t e - b o r n i t e , and  b o r n i t e phase.  cha1cocite:bornite. solution  Digenite-Bornite  gap.  p. 195)  Sustut  shows the chal copy r i te-born i te  b o r n i t e s have about  c h a l c o p y r i t e (approximately  3 mole percent  from the diagram, a temperature of over  ature determinations  are t e n t a t i v e at best and,  10 volume  percent  c h a l c o p y r i t e ) which  400'C. However such one  solid  can say w i t h  indi-  temper-  confidence,  161  350 cc-bn ss.  300 \  250  High bn N.  High bn + cc  _*  200 us B & e  L  *  ^228*  s  I_-l\fa'J Low>bn U  co 150  o. e  Low bn + cc  >- 100 O O O O Tt K * • + • + +  50 ~  10  0  C u  2  20  30  40 50 60 Mol per cent  s  F i g u r e 77:  70  80  90 "  S t a b l e phases on the j o i n  5  100 , j 4  Cu^FeS^-  (from B r e t t , 1963, p. 194).  Cu.S  1  350  D D U  300  0 0 0  D  a  i  O  O  bn-dg ss. o , 0  o  o  r  1 —T  /  p 250  ODD  oal  High bn +high dg  \ _ 228°  o = 200 a k_  •  D O  S  /„S_  O  SLJZ-l-M  Low bn + high dg  a>  High dg  £ 150  r"  100  2  t  10 5  F i g u r e 78: Cu  9  2  /  i i/ Lowdg(+dj) /  50 ~ 0 Cu . S 9  ^.B^**"""  S  5  1 / 1  20  30  Low  §  §  1  dg  +  low  §  1  bn  6 SS  6  1  40 50 60 Mol per cent  1  70  -J-  80  S t a b l e phases on t h e j o i n  (from B r e t t , 1963, p. 193).  90  100 Cu FeS 5  Cu^FeS^-  4  162  1  1  1  1  1  1  *  400  1  1  -8  1 * ><• l  \  350 300  ( High bn-i-^T  4-cp  i i  High bn + cp  -1 8  u  250  228°  200  1  Low bn-T  100  i  Low bn +cp  150  ii  i i i 1 1  T  *-  50  ! 9 1  0 10 CuFeS2_x  Figure 79: CuFeS  i  i  20  30  i  i  40  50  1  60  2  70  ? 1  80  Mol per cent S t a b l e phases on the j o i n  (from B r e t t , 1 9 6 3 , p. 1 9 5 ) .  90  I I I !  100 Cu FeS 5  Cu^FeS^-  4  163 only  roughly  approximates  the m i n e r a l d e p o s i t i o n  temperatures.  There were two d i s t i n c t b o r n i t e s o l i d s o l u t i o n s ores.  In one ( b o r n i t e  I)  in the S u s t u t  the phases b o r n i t e , c h a l c o c i t e and d i g e n i t e a r e  p r e s e n t , and in the o t h e r d i g e n i t e occur.  present  (bornite  II)  the phases b o r n i t e , c h a l c o p y r i t e and  But the phases c h a l c o c i t e and c h a l c o p y r i t e were not  in e q u i -  l i b r i u m and thus t h e r e was not a c h e m i c a l t i e l i n e between the two phases. Fig.  80 has  t h r e e diagrams,  system a t 2 0 0 ' ,  300',  from Yund and K u l l e r u d  and 4 0 0 ' C .  (1966), f o r the Cu-Fe-S  The 200'C diagram shows c h a l c o c i t e and  d i g e n i t e e x i s t i n g as s e p e r a t e phases, and both b o r n i t e and c h a l c o p y r i t e have small  solid solution fields.  T i e l i n e s connect c h a 1 c o c i t e - d i g e n i t e ,  c i t e - b o r n i t e , d i g e n i t e - b o r n i t e and b o r n i t e - c h a 1 c o p y r i t e .  chalco-  The d i g e n i t e - c h a 1 -  c o c i t e - b o r n i t e s c o u l d have formed at t h i s t e m p e r a t u r e , as c o u l d the c h a l c o p y r i t e - b o r n i t e s , but a c h a l c o p y r i t e - d i g e n i t e - b o r n i t e c o u l d not have  formed  as a s o l i d s o l u t i o n at t h i s t e m p e r a t u r e (because d i g e n i t e - c h a l c o p y r i t e a r e not  in e q u i l i b r i u m ) .  cocite  At 300'C d i g e n i t e - b o r n i t e form a s o l i d s o l u t i o n ,  i s a s o l i t a r y phase and c h a l c o p y r i t e has a l a r g e r s o l i d  field.  solution  Both types o f b o r n i t e c o u l d have formed at t h i s t e m p e r a t u r e  the d i g e n i t e - b o r n i t e and the c h a l c o p y r i t e s o l i d s o l u t i o n s the c h a l c o c i t e f i e l d  a r e c o n n e c t e d and  At 400'C an e q u i v a l e n t  Very g e n e r a l l y , the b o r n i t e s o l i d s o l u t i o n s  o f f o r m a t i o n o f g r e a t e r than 2 0 0 ' C . exsolution  because  i s s e p a r a t e from the c h a l c o p y r i t e thus the d i s e q u i l i b r i u m  between t h e s e two phases i s m a i n t a i n e d . exists.  chal-  situation  i n d i c a t e temperatures  A l l of the temperatures s u g g e s t e d by  t e x t u r e s a r e c o n s i s t e n t w i t h those d e r i v e d from study o f  metamor-  p h i c m i n e r a l assemblages above. The d i g e n i t e - c h a 1 c o p y r i t e - b o r n i t e  intergrowths  are a l s o  i n t e r e s t i n g be-  cause they q u a l i t a t i v e l y show the unmixing path of components, ginal  b u l k c o m p o s i t i o n t o e x s o l v e d p r o d u c t s , due to d e c r e a s i n g  When o r i g i n a l l y formed at e l e v a t e d t e m p e r a t u r e s , t h i s b o r n i t e t a i n e d excess  i r o n and c o p p e r .  With a decrease  from an  ori-  temperatures. (_i_e. l l b )  in t e m p e r a t u r e , the  con-  iron,  6 0 Weight per cent S  ,  Weight per cent  —  200*C F i g u r e 80: 1966,  Isothermal s e c t i o n s  pp. 472-474).  pyrrhotite,  in the Cu-Fe-S system at 200,  (chalcocite,  cc; digenite,  po; p y r i t e , py; c o v e l l i t e , c v ;  dg; b o r n i t e ,  idaite,  id).  300,  400'C  (from Yund and  bn; c h a l c o p y r i t e ,  Kullerud,  cp; cubanite,  cb;  . 60 Weight per cent S •A  A  TV  cb,  bru  Fe  Cu  Weight per cent 300'c  Figure  80  (cont'd.)  167 was e x p e l l e d from the b o r n i t e l a t t i c e , as  laths  such t h a t c h a l c o p y r i t e began forming  in the c r y s t a l l o g r a p h i c d i s c o n t i n u i t i e s o f the b o r n i t e .  This expul-  s i o n o f c h a l c o p y r i t e , moved the b u l k b o r n i t e c o m p o s i t i o n from c h a l c o p y r i t e into copper-rich areas. a f u r t h e r decrease rich for was  With the e x s o l u t i o n o f most o f t h e c h a l c o p y r i t e and  in t e m p e r a t u r e , the b o r n i t e s o l i d s o l u t i o n was too c o p p e r -  i t s s t o i c h i o m e t r i c composition.  r e a c h e d , d i g e n i t e was e x s o l v e d  ponent  When a t e m p e r a t u r e o f above 200'C  in o r d e r t o remove the c o p p e r - r i c h com-  (at the t e m p e r a t u r e o f 200'C and below, d i g e n i t e and b o r n i t e have  sep-  e r a t e s t a b i l i t y f i e l d s , thus the two m i n e r a l s c o u l d be in s o l i d s o l u t i o n til  this  temperature- f i g , 80).  The removal o f d i g e n i t e from the s o l i d  s o l u t i o n , moved the b u l k b o r n i t e c o m p o s i t i o n towards Covellite after  5-5.4  described  l a t e r replacement o f d i g e n i t e .  Comparable  digenite grains.  l a r way.  almost  c o v e l l i t e o c c u r s as a  as c o v e l l i t e s e l v a g e s on f r a c t u r e s  replaced degenite  i s due to o x i d a t i o n o f  in the S u s t u t samples  Flame l a m a l l a e patches o f S i l l i t o e et_  cutting the  in a s i m i -  a_]_. (1969) a r e the same as  the r o s e t t e replacements d e s c r i b e d by t h i s w r i t e r . 5.5 - 5 D i g e n i t e and C o v e l l i t e a f t e r  Bornite  To account f o r d i g e n i t e - c o v e l 1 i t e replacement of b o r n i t e at S u s t u t , erence as  i s made to T a y l o r and K u l l e r u d ' s  i l l u s t r a t e d in f i g . 8 l .  samples blages  ref-  (1970) study o f the C u - F e - S - 0 system  Phases p r e s e n t  var-  who r e c o r d c o v e l l i t e flame  T h i s r e p l a c e m e n t , they s t a t e ,  C o v e l l i t e has  which  replacement has been r e p o r t e d by  (eg. S i l l i t o e and C l a r k e , 1969)  l a m a l l a e in d i g e n i t e masses, as w e l l  digenite.  intergrowths of sulphides  r e s u l t e d from unmixing o f s o l i d s o l u t i o n s ,  ious a u t h o r s  stoichiometry.  Digenite  U n l i k e the p r e v i o u s l y certainly  un-  i n t h i s s y s t e m , but n o t ' in the  s t u d i e d a r e : p y r r h o t i t e , i d a i t e and c u b a n i t e .  S t a b l e phase assem-  in the S u s t u t d e p o s i t a r e c o p p e r - c h a l c o c i t e - m a g n e t i t e - h e m a t i t e , c h a l -  coc i t e - d i gen i te-hemat i t e - m a g n e t i t e , c h a l c o c i t e - b o r n i te-magnet i t e - h e m a t i t e , cha1 copyr i t e - p y r i te-hemat i t e - m a g n e t i t e and b o r n i t e - c h a l c o p y r i te-hemat i t e -  Cu  F i g u r e 81:  Fe  Phase  relations  i n the C u - F e - S - 0 system at  300'C (from T a y l o r and K u l l e r u d , 1970, abbreviations  are the same as those  H e m a t i t e , hm; m a g n e t i t e , mg.  p. 316).  in figure  80.  Phase  169 magnetite.  Covellite  on S u s t u t and  is never  is not a primary  s t a b l e phase w i t h any o t h e r  s t a b l e with magnetite  phases  as a phase in the Cu-Fe-S-0  system. As  the authors  a compositional  ( i b i d . ) s t a t e , a b u l k c o m p o s i t i o n , on the s u l p h u r s i d e of  l i n e through  not be s t a b l e w i t h magnetite The  presence  o f hematite,  c h a l c o c i t e - b o r n i t e - c h a l c o p y r i t e - p y r i t e , would a l o n e and  must n e c e s s a r i l y be  were thus on the s u l p h u r s i d e .  c o v e l l i t e within s t a b i l i t y  fields.  e x i s t a n c e w i t h b o r n i t e , i s o x i d i z e d to hematite, change toward s u l f u r a c r o s s the b o r n i t e s o l i d slightly  i d a i t e and/or c o v e l l i t e  appears  t h a t f u r t h e r o x i d a t i o n causes  solution f i e l d . will  must  Oxidation  lead to forma-  pp.  317~318).  breakdown o f b o r n i t e to  It  covellite.  view h e l d by t h i s w r i t e r i s t h a t s u l p h i d e s were i n t r o d u c e d i n t o host  rocks c o n t a i n i n g magnetite.  As  began which s t a r t e d  down magnetite  to form h e m a t i t e . ellite  in co-  the b o r n i t e c o m p o s i t i o n  rims on b o r n i t e " ( i b i d , total  indi-  This oxid-  " I f magnetite,  beyond that r e q u i r e d to c o n v e r t a l l magnetite  tion of  The  present.  coeval w i t h the s u l p h i d e s in the Sustut o r e s  c a t e s t h a t the bulk compositions a t i o n a l s o brought  hematite  to break  B o r n i t e was  the s u l p h i d e s were p r e c i p i t a t i n g , o x i d a t i o n  altered  by a l a t e r supergene o x i d a t i o n .  is a l s o shown by  l i m o n i t e weathering  first  and  r e l e a s e i r o n from  to d i g e n i t e and  silicates  finally  t o cov-  Supergene o x i d a t i o n o f o r e m i n e r a l s  of p y r i t e and  l i m o n i t e rims on c h a l c o -  pyrite.  5.6  R e l a t i o n s h i p o f Ore Veins and  Comparison o f ore v e i n s and  Lenses  lenses shows s t r i k i n g  mineralogy,  i n t e r g r o w t h t e x t u r e s , gangue mineralogy,  e r a l s occur  in both d e p o s i t - t y p e s , and  with  r e s p e c t to each o t h e r  seminated (ie.  through  I, Ma,  intergrowth  Mb)  (except p y r i t e , which rocks).  in v e i n s as w e l l as  t e x t u r e s in both modes.  etc.  in o r e  A l l m e t a l l i c min-  have the same r e l a t i v e p r o p o r t i o n s  the host vol canic1 a s t i c occur  similarities  i s much more abundantly  dis-  A l l t h r e e b o r n i t e types  l e n s e s , and  they have the same  D i g e n i t e is e x s o l v e d from  chalcocite  170 i n v e i n s and l e n s e s , a l s o .  The d i s e q u i l i b r i u m between some s u l p h i d e phases  i s m a i n t a i n e d in the two modes o f o c c u r r e n c e ( i e . c h a l c o c i t e does not o c c u r w i t h c h a l c o p y r i t e , n a t i v e copper o c c u r s w i t h c h a l c o c i t e o n l y , In o r e l e n s e s ,  the o r e m i n e r a l s o c c u r m a i n l y as open space f i l l i n g s w i t h -  i n the host c o n g l o m e r a t e s , which i s what the o r e v e i n s a r e a r e f r a c t u r e - f i l l i n g s ) . In both c a s e s , grown w i t h the same gangue m i n e r a l s .  ( i e . the v e i n s  the o r e m i n e r a l s a r e e x t e n s i v e l y Those  w i t h i n the g e n e r a l a r e a o f the d e p o s i t .  It appears  formed at the same time as the metamorphic m i n e r a l s The common n a t u r e o f the o r e m i n e r a l o g r a p h y ,  metamorphic f a c i e s  t h a t the o r e m i n e r a l s i n both  cases.  in both v e i n s and  lenses,  suggests t h a t o r e m i n e r a l s , in both modes o f o c c u r r e n c e , formed  from the same- s o l u t i o n s . e r a t e ore-forming episodes  For example, i t i s very hard to e n v i s a g e developing equivalent general  bornite  two s e p assemblages  w h i c h e v o l v e d i n t o e x a c t l y the same t h r e e b u l k b o r n i t e c o m p o s i t i o n s bornites  inter-  i n t e r g r o w n gangue m i n e r a l s , p r e h -  ni t e - e p i d o t e - c a r b o n a t e - q u a r t z , a r e a l s o o f the h i g h e s t  very s t r o n g l y  etc.).  i n both v e i n s and l e n s e s must have formed from t h e same  Another f a c t o r suggesting  ( i e . the  system).  a common o r i g i n f o r the two o r e - f o r m s ,  i s the  i n t e r g r o w t h o f o r e m i n e r a l s o f both forms w i t h the same metamorphic m i n e r a l s . The metamorphic event which caused development of the metamorphic m i n e r a l s (gangue) was o b v i o u s l y  synchronous  with ore mineral  introduction.  Thus,  the  o r e m i n e r a l s o f both modes formed a t the same time ( i e . t h e r e were not two d i f f e r e n t metamorphic e v e n t s which caused development o f the metamorphic mi n e r a l s ) . F i n a l l y the i n t e r - r e l a t i o n s h i p between the two o r e - f o r m s shown by t h e i r common s p a t i a l o c c u r r e n c e s . o u t the d e p o s i t  not a c t u a l l y c u t through the ore  (again g r a d i n g o u t w a r d s ) . lenses.  strongly  Numerous examples a r e seen  in which o r e v e i n s appear below o r e l e n s e s  i n t o them) and above o r e l e n s e s  i s most  (actually  through-  grading  The o r e v e i n s  do  171 A good example of this vein-lens sequence occurs  in the North Zone. At  sample location W36, well developed gangue-sulphide veins crop out. below these veins, the ore lens by (sample location) W32 occurs. cut through outcrop expressions of this lens. another group of sulphide-rich veins occur area, small ore lenses with • the c l i f f  Just  No veins  However, below this lens,  (W96).  Still  further below this  interconnected ore veins occur to the base of  (_i_e. sample locale W i l l ) .  At W104 abundant ore veins occur above a tabular ore lens.  A small ore  lens occur at sample area W2 which is cut by a cha1cocite-rich vein at one of i t s lateral extremities.  It appears that the lens here, so isolated from  other copper occurrences, may owe i t s existence to the same f l u i d s which prec i p i t a t e d the vein material.  Near sample l o c a l i t i e s W10-W11-W12, an ore lens  appears to-be superimposed on country  rock which has been cut by numerous,  small sulphide-rich veins. And  so on through the deposit, i t appears that the veins and lenses are  s p a t i a l l y related in that veins are abundant above and below, but not in, ore lenses. to,  Thus, the writer suggests that the veins appear to have been feeders  and releases from, the ore lenses for ore-forming  fluids.  The lenses, then,  l i k e the veins, are post-dyke and p r e - f a u l t i n g . 5-7 Zonation of M e t a l l i c Minerals If the v e r t i c a l with d r i l l  in Ore Lenses  d i s t r i b u t i o n of the ore minerals  is viewed v e r t i c a l l y ( i e .  core), a general zonation pattern of the minerals  becomes apparent.  The four cross-sections A-A ,B-B ,C-C and D-D' (attached - in back) show the 1  1  1  d i s t r i b u t i o n of sulphides and native copper as a histogram estimated  based on v i s u a l l y  amounts (these cross-sections were constructed from a computer gen-  erated s t r i p log of depth, and amount and type of m e t a l l i c mineralization at each l e v e l , variables that had been recorded consistently in relogging of the cores).  The most complete zonal pattern is shown in DDH 88 where a very minor  amount of native copper is central to a large chalcocite zone. This  172 zone  is f r i n g e d successively  by o v e r l a p p i n g zones c o n t a i n i n g s m a l l e r  o f b o r n i t e and c h a l c o p y r i t e , f o l l o w e d by an o u t e r zone o f abundant Elsewhere  throughout  wel1-developed  DDH 88 t h e r e a r e s m a l l e r s u l p h i d e  holes,  i s p e r f e c t l y formed. w i t h i n a given d r i l l  this zonation  some w i t h  i s developed i r r e g u l a r l y and  One zone, o r more, can be e n t i r e l y o r p a r t l y hole.  seldom  missing  R e l a t i v e amounts o f m i n e r a l s w i t h i n t h e i r  p e c t i v e zones v a r i e s c o n s i d e r a b l y ,  from d r i l l  hole to d r i l l  res-  hole, also.  (It  be noted t h a t most o f the c h a l c o c i t e , a s i d e from t h a t a s s o c i a t e d  with  n a t i v e c o p p e r , c o n t a i n s a b o r n i t e component. bution  Thus, the r e a l b o r n i t e  i s more e x t e n s i v e than shown i n the a t t a c h e d  cross-sections  A-A , 1  B-B ,  C-C  1  and D-D  1  (attached -  1  distri-  cross-sections).  D e t a i l e d d e s c r i p t i o n s o f m i n e r a l z o n i n g , e x h i b i t e d by the d r i l l  dix  pyrite.  zonation.  In o t h e r d r i l l  should  lenses,  amounts  in b a c k ) , a r e  holes  in  in Appen-  I I I. This  z o n i n g sequence  i s a l s o found  copper o c c u r s o n l y w i t h c h a l c o c i t e . bornites  (ie. bornite  taining chalcopyrite.  I)  but  C h a l c o c i t e o c c u r s w i t h more c o p p e r - r i c h  F u r t h e r m o r e , cha1 c o p y r i t e - b o r n i t e s a r e in c o n t a c t w i t h C h a l c o p y r i t e i s best developed where  s u l p h i d e but does have a g r a d a t i o n w i t h p y r i t e .  is strongest  z o n a t i o n through  an o u t e r p y r i t e zone c o m p l e t e l y s u r r o u n d i n g example DDH 54 c o n t a i n s m a i n l y p y r i t e but level  is a  And l i k e w i s e p y r i t e  i t s only sulphide,  o f a major copper zone exposed W92 which appears  with  For  i s c l o s e t o and on the same s t r a t i -  in s e c t i o n D-D , 1  the  the p r o p e r t y as w e l l ,  some c o p p e r - r i c h a r e a s .  as the c h a l c o c i t e zone o f DDH 110.  from the c o p p e r - r i c h ore lenses p y r i t e as  it  when s o l i t a r y .  There may a l s o be a l a t e r a l  graphic  Native  i s not found w i t h c h a l c o p y r i t e , o r b o r n i t e c o n -  c h a l c o p y r i t e but not p y r i t e . solitary  in p o l i s h e d s e c t i o n s t u d i e s .  A l s o DDH 132 at a d i s t a n c e contains only p y r i t e .  With  c o r e from DDH 2 5 i s o f an area to the west  in c r o s s - s e c t i o n  C-C . 1  P y r i t e occurs  near  t o be an o u t e r f r i n g e to the west of the main copper  sul-  173 p h i d e o c c u r r e n c e s o f the N o r t h Zone. Robertson  (1975) d e s c r i b e d a somewhat s i m i l a r z o n a t i o n p a t t e r n in a copper  d e p o s i t near Mount Bohemia, M i c h i g a n , where c h a 1 c o c i t e - b o r n i t e - h e m a t i t e zones grade  i n t o p y r i t e - c h a l c o p y r i t e areas w i t h i n c r e a s i n g d i s t a n c e from a f a u l t ,  a l o n g which the m i n e r a l i z i n g f l u i d s a p p a r e n t l y f l o w e d . e s s e n t i a l l y the same as t h a t o f the S u s t u t copper c o r e s .  deposit,  is  including rare native  There a r e a l s o two b o r n i t e types p r e s e n t .  s t u d i e s , Robertson  This zonation  Through chemical  found t h a t copper was d i s t r i b u t e d s y m m e t r i c a l l y r e l a t i v e  t o the f a u l t and d e c r e a s e d  in abundance outwards  than 0.1  percent.  has the same s y m m e t r i c a l d i s t r i b u t i o n and decreased  outwards  from the f a u l t , b u t . i t s  of copper.  This  Sulphur  lateral  from t h i s f a u l t , t o  e x t e n t was much g r e a t e r than t h a t  increased d i s t a n c e of sulphur occurrence corresponded  the appearance o f p y r i t e . away from the f a u l t . and near the S u s t u t  Total  t t appears  less,  with  i r o n on the o t h e r hand showed no v a r i a t i o n that total  Copper d e p o s i t  too.  i r o n i s more o r l e s s  u n i f o r m in  174 CHAPTER 6:  b.l  DISCUSSION OF DATA AND POSSIBLE GENETIC MODEL  I n t r o d u c t i o n and Summary o f P h y s i c a l  Features  In t h i s c h a p t e r the v a r i o u s g e n e t i c models f o r the S u s t u t suggested by o t h e r a u t h o r s w i l l  be c o n s i d e r e d .  Copper  deposit  Finally this writer will  p r e s e n t a d e t a i l e d g e n e t i c model based on the r e s u l t s o f h i s own s t u d i e s .  Any  such model would have to t a k e i n t o account and e x p l a i n the f o l l o w i n g p h y s i c a l and c h e m i c a l f e a t u r e s o f the S u s t u t 1) Moosevale  The d e p o s i t has a l o c a l  deposit. high  in metamorphic grade compared w i t h o t h e r  F o r m a t i o n rocks at the same s t r a t i g r a p h i c l e v e l  the d e p o s i t  elsewhere, that  i s p r e h n i t e - p u m p e l 1 y i t e f a c i e s and the o t h e r Moosevale  rocks  is, are  laumontite f a c i e s . Copper and s u l p h i d e m i n e r a l s o c c u r m a i n l y as open space f i l l i n g s ,  2)  o r as o v e r g r o w t h s  and replacements o f p r e - e x i s t i n g p y r o g e n i c m i n e r a l s , and are  intergrown i n t i m a t e l y w i t h t y p i c a l pumpellyite  metamophic m i n e r a l s o f the p r e h n i t e -  facies. Major c o n c e n t r a t i o n s o f copper m i n e r a l s a r e found in t a b u l a r  3)  w i t h i n the v o l c a n i c l a s t i c h o s t r o c k s , t h a t a r e p a r a l l e l abundant  in the upper 60 m o f the v o l c a n i c  4)  5)  swarms o f t h i n v e i n s w i t h the same  i s found in the t a b u l a r c o p p e r - r i c h  Equivalent types, proportions,  t o bedding and a r e most  pile.  Ore m i n e r a l s a l s o o c c u r i n l o c a l  gangue m a t e r i a l as  zones  lenses.  i n t e r g r o w t h s and replacement t e x t u r e s  o f o r e m i n e r a l s are found i n the l e n s e s and v e i n s .  In f a c t , the two g e o m e t r i c  forms o f copper c o n c e n t r a t i o n a r e r e l a t e d s p a t i a l l y and are i n t e r c o n n e c t e d . 6)  T a b u l a r zones and v e i n s are r i c h i n Cu, N i , Zn, Ca, and S r ,  g e n e r a l l y a r e p o o r e r i n Rb, MgO, S i 0£, and A12*^3 r e l a t i v e to c o u n t r y Also  the Cu c o n t e n t s show no g r a d a t i o n from c o p p e r - r i c h l e n s e s  copper-poor  r o c k s , j u s t a sharp break  in v a l u e s .  and  rocks.  to e n c l o s i n g  175 Temperatures o f f o r m a t i o n o f t h e d e p o s i t , as determined from meta-  7)  morphic m i n e r a l assemblages and s u l p h i d e m i n e r a l  intergrowths, are indicated  as b e i n g o v e r 200'C and under 403*C, most l i k e l y  300 t o 4 0 0 ' C .  The s u l p h i d e m i n e r a l s have d i s t i n c t s t a b l e assemblages and a  8) zonation  is present  i n the o r e lenses w i t h n a t i v e copper cores  changing  zones o f c h a l c o c i t e , c h a l c o c i t e and b o r n i t e , b o r n i t e and c h a l c o p y r i t e ,  c h a l c o p y r i t e and g r e e n o c k i t e , f i n a l l y w i t h an outermost 9) veins  Age o f m i n e r a l i z a t i o n i s p r o b a b l y post-Lower  c u t t h e dyke and the dyke i s most  the Lower J u r a s s i c H a z e l t o n  6.2 P r e v i o u s l y 6.2,1  Syngenetic Syngenetic  fringe of p y r i t e . Jurassic  (as t h e o r e  c o r r e l a t i v e with intrusions  Suggested  Origins  Hypotheses models have been s u g g e s t e d v e r b a l l y t o the a u t h o r and a r e reports d e a l i n g w i t h o r i g i n of the Sustut.  At l e a s t t h r e e v o l c a n o g e n i c - s y n g e n e t i c  d e p o s i t i o n a l models have been  p r o p o s e d , a l l o f which c o u l d have been c o m p l i c a t e d by l a t e r superimposed The f i r s t s y n g e n e t i c model were d e p o s i t e d  involves volcanics  clastics  The s u l p h i d e s  t o . b e i n t e r b e d d e d w i t h t u f f a c e o u s mudstones,  o f a r e n i t e s d e r i v e d from a basinal  (pyroclastics  and l a v a s )  features.  which  i n s h a l l o w b a s i n s , w i t h near shore e n v i r o n m e n t s , where t h e v o l -  canism was induced by r i f t i n g and f a u l t i n g . considered  in  Group).  described b r i e f l y in proprietary deposit.  likely  to o u t w a r d l y  the a d j a c e n t h i g h e r ground.  v o l c a n i c sequence w i t h t h e s u l p h i d e s by f u m a r o l i c a c t i v i t y .  being  i n t h i s case a r e  l i m e s t o n e s , and a v a r i e t y The second model  involves  introduced into the pyro-  F i n a l l y the t h i r d model would have t h e s u l p h i d e s  e x i s t i n g as e j e c t a  i n the f l a n k s o f a c e n t r e o f v o l c a n i c i t y (eg. t h e m i n e r a l r  ization previously  formed a stockwork  in a volcanic  The most c o m p e l l i n g argument a g a i n s t  throat).  any o f these s y n g e n e t i c  i s t h a t t h e o r e m i n e r a l s a r e not c o n c e n t r a t e d i n the l i t h i c v o l c a n i c  hypotheses clasts,  but o c c u r as open space f i l l i n g s and a s s p a t i a l and a p p a r e n t l y g e n e t i c  inter-  176 F u r t h e r m o r e , those o r e m i n e r a l s which a r e  growths w i t h metamorphic m i n e r a l s . present  in l i t h i c c l a s t s , o c c u r as overgrowths  s i l i c a t e m i n e r a l s , o r as amygdules.  and replacements o f  A l s o , n e i t h e r s y n g e n e t i c model can account  f o r the zonal d i s t r i b u t i o n - o f s u l p h i d e s around n a t i v e copper in regard to the f i r s t certain  suggestion,  interbeds, within a basinal  d i f f e r e n t sedimentological facies t o one type o f s e d i m e n t a r y d e p o s i t mudstones, detrital  Sustut  though o r e l e n s e s a r e r e s t r i c t e d t o  sequence, the i n t e r b e d s a r e not d i s t i n c t l y  ( i e . host  rocks to the l e n s e s a r e not r e s t r i c t e d  i n the v o l c a n i c l a s t i c p i l e ,  e n v i r o n m e n t , v a r y i n g o n l y by minor p h y s i c a l  sediments  deposit  ions).  for  instance  characteristics).  evidence f o r fumarolic a c t i v i t y  i n d i c a t i v e o f such a c t i v i t y  (the c a r b o n a t e s p r e s e n t on S u s t u t  mineralization.  in a vent which was  s h o u l d be c o n t a i n e d w i t h i n  i n d i c a t e a p r e - b r e c c i a t ion age o f  D e r i v e d Ore F l u i d Model  (1974) model f o r the o r i g i n o f n a t i v e copper d e p o s i t s w i t h i n the  Keweenawan b a s a l t s o f M i c h i g a n has been quoted as an analogue o f the deposit  deposit-  Such f e a t u r e s have not been seen in the d e p o s i t .  Metamorphica11y Jolly's  in t h e .  are r e e f s , not c h e m i c a l  d i s r u p t e d e x p l o s i v e l y , some s u l p h i d e s  v o l c a n i c c l a s t s , and t e x t u r a l f e a t u r e s s h o u l d  In the  i s p r e s e n t , and no  (eg. z e o l i t e s ) o c c u r  F i n a l l y , i f the s u l p h i d e s o c c u r r e d as a stockwork  subsequently  6.2.2  cores.  but are w i t h i n i n t e r b e d s which had the same g r o s s c h e m i c a l and  second c a s e , no p h y s i c a l chemical  pre-existing  (eg. H a r p e r , 1977).  have many s i m i l a r g e o l o g i c a l  The two d e p o s i t s c o n t r a s t markedly features.  Sustut  i n s i z e , but  N a t i v e copper i n the Keweenawan  basalts  o c c u r s as open space f i l l i n g s , and l e s s commonly as replacements o f the host rock, with c h l o r i t e - a l b i t e - p u m p e l l y i t e - q u a r t z - p r e h n i t e - e p i d o t e , or with p r e h n i t e . Background  copper c o n t e n t s o f u n a l t e r e d p o r t i o n s o f t h e s e b a s a l t s  t o 90 ppm. that  roughly  There i s a l s o a z o n a t i o n o f metamorphic m i n e r a l s  range from kO  in these  basalts  p a r a l l e l s s t r a t i g r a p h y , wherein a 1 b i t e - p r e h n i t e - 1 a u m o n t i t e - c h l o r i t e -  a n a l c i m e - s p h e n e and r a r e n a t i v e copper assemblages o c c u r at the top o f  the  b a s a l t i c p i l e ; a 1bite-pumpel1yite-prehnite-native copper-quartz-chlorite-sphene-  177 e p i d o t e a r e i n t h e m i d d l e ; and a l b i t e - e p i d o t e - q u a r t z - c h l o r i t e - s p h e n e purnpel l y i te assemblages a r e a t the base. Jolly  s u g g e s t s t h a t t h e development o f t h e deepest metamorphic m i n e r a l  assemblage was caused by d e h y d r a t i v e metamorphism which e x p e l l e d water from the basalts  at this  level.  Copper and z i n c were l e a c h e d o u t by t h i s water removal  and were c o n t a i n e d as c h l o r i d e complexes through t h e v o l c a n i c p i l e u n t i l  in the waters.  These s o l u t i o n s  they reached a l e v e l where temperature and  p r e s s u r e were such t h a t h y d r a t i v e metamorphism c o u l d t a k e p l a c e . metamorphism brought  rose  This  hydrative  about t h e development o f p u m p e l l y i t e (and p r e h n i t e )  c a p t u r e d some o f t h e r i s i n g w a t e r s .  The copper  which  ions were p r e c i p i t a t e d w i t h  t h i s p u m p e l l y i t e development due t o r e d u c t i o n o f Cu  ions by o x i d a t i o n o f  m a g n e t i t e t o h e m a t i t e , and breakdown o f p u m p e l l y i t e t o e p i d o t e .  Z i n c on the  o t h e r hand d i d not p r e c i p i t a t e and was c o m p l e t e l y removed from the system.  Copper s u l p h i d e s  were not developed because t h e S  c o n t e n t o f t h e w a t e r s was  too 1 ow. There a r e a number o f reasons why t h i s model Sustut  deposit.  Throughout  i s not a p p l i c a b l e t o the  the upper member o f t h e Moosevale  F o r m a t i o n , meta-  morphic m i n e r a l assemblages a r e f a i r l y c o n s t a n t w i t h no f a c i e s v a r i a t i o n s w i t h i n the p i l e .  E x t r a p o l a t i o n o f the types o f a l t e r a t i o n present below t h e  616 m o f t h e Moosevale  Formation v i s i b l e  in d r i l l  c o r e i s tenuous,  but Burns  (1973) d e s c r i b e d a l l t h e rocks as having p r e h n i t e - p u m p e l 1 y i t e grade According  metamorphism.  to B u r n s , t h e f i r s t appearance o f an a l t e r n a t i v e f a c i e s does not  occur u n t i l  t h e a c t i n o l i t e - b e a r i n g A s i t k a Group  s t r a t i g r a p h i c a l l y below the Sustut  i s e n c o u n t e r e d , t h a t i s 2400 m  d e p o s i t . The background  the A s i t k a Group a r e comparable t o those o f t h e Moosevale to Monger (1977)  copper c o n t e n t s o f Formation,  (jj_e. no g r e a t d e p l e t i o n i n copper c o n t e n t s  On t h e W i l l o w p r o p e r t y , t o t h e s o u t h , a c r o s s Sustut  visible  is apparent).  the Sustut  R i v e r from t h e  d e p o s i t , s h a l e a t t h e top o f the lower member o f the Moosevale  ation contains  disseminations  according  o f c h a l c o p y r i t e and c h a l c o c i t e , g r a d i n g  Formup t o  178 30 volume p e r c e n t (Church 1973)°  This sulphide m i n e r a l i z a t i o n , well  the s t r a t i g r a p h i c l e v e l o f the S u s t u t h y d r a t i v e system e n v i s a g e d by J o l l y not p r e s e n t  deposit,  below  i m p l i e s t h a t the d e h y d r a t i v e -  f o r t h e Keweenawan b a s a l t s , e i t h e r was  i n the f o r m a t i o n o f the S u s t u t  d e p o s i t , o r encompassed a much  t h i c k e r s t r a t i g r a p h i c s e c t i o n below the upper member o f the Moosevale A n o t h e r problem o f a p p l i c a t i o n i n v o l v e s m e t a l l i c components between the two d e p o s i t s . mineral  present  deposits.  Formation.  the b a s i c d i f f e r e n c e i n N a t i v e copper i s the o n l y o r e  i n the Keweenawan d e p o s i t s and s u l p h u r  i s d e f i c i e n t in these  At S u s t u t , on the o t h e r hand, n a t i v e copper i s o n l y a minor  constituent with sulphides into Sustut  predominating.  r o c k s a l s o had a l a r g e s u l p h u r  Thus, any f l u i d s  i n t r o d u c i n g copper  component, w h i c h may have been even  g r e a t e r than t h a t o f copper (j_e. p y r i t e has a g r e a t e r s p a t i a l e x t e n t than do any o f t h e copper s u l p h i d e s ) . d e r i v a t i o n o f s u l p h u r from host i n t r o d u c t i o n of sulphur  J o l l y ' s model does not take i n t o account r o c k s nor does i t suggest any means f o r  i n t o the o r e - f o r m i n g chemical system by metamorphism.  Z i n c i n the S u s t u t d e p o s i t  i s s l i g h t l y e n r i c h e d w i t h i n copper  zones and shows no measurable d e p l e t i o n in o t h e r areas o f host zinc  i n the Keweenawan b a s a l t s  sulphide  rock,  whereas  i s d e p l e t e d i n dehydrated areas and i s  flushed  out o f the o r e s y s t e m . A n o t h e r major f e a t u r e , not e x p l a i n e d by J o l l y ' s model, i s the m i n e r a l z o n a t i o n found  in v e r t i c a l  advanced upwards  sections  through the S u s t u t  through o r e l e n s e s o f S u s t u t .  If  fluids  s e c t i o n from zones o f d e h y d r a t i o n , then  any z o n a t i o n formed should be o n l y o n e - s i d e d as the chemical changes i n w a l l rock-ore f l u i d  r e a c t i o n s would be a t the f r o n t o f the advancing f l u i d s o r  behind t h e f r o n t , but not on e i t h e r s i d e o f a c e n t r a l core as a c t u a l l y seen. Harper process,  (1977), u s i n g J o l l y ' s model as a b a s i s f o r the S u s t u t  ore-forming  thought t h a t p y r i t e may have p r e - d a t e d copper m i n e r a l i z a t i o n and  a c t e d as a c a t a l y s t to copper p r e c i p i t a t i o n ( i e . o r i g i n a l p y r i t e may have  thus  179 f u r n i s h e d some o f the s u l p h u r a l s o argued a g a i n s t  needed to form the copper s u l p h i d e s ) .  a " c o n v e n t i o n a l hydrothermal plumbing system  because o f a l a c k o f f e e d e r s f o r hydrothermal The arguments a g a i n s t  Harper's  epigenesis"  solutions.  ideas above a r e t h a t p y r i t e has  p r o v e d , upon c l o s e e x a m i n a t i o n , to be an e p i g e n e t i c m i n e r a l w i t h copper s u l p h i d e f o r m a t i o n .  Harper  indeed  penecontempouraneous  F i n a l l y , the o r e v e i n s do appear to be  i n t e r c o n n e c t e d w i t h o r e l e n s e s and c o u l d c o n c e i v a b l y be a plumbing  system.  The w r i t e r does not w i s h to p r e c l u d e the p o s s i b l e minor c o n t r i b u t i o n o f m e t a m o r p h i c a l l y d e r i v e d w a t e r and i o n s , but f o r m a t i o n o f S u s t u t o r e  lenses  s o l e l y , o r even d o m i n a n t l y , by these waters does not seem p l a u s i b l e a c c o r d i n g t o the p h y s i c a l and c h e m i c a l paramenters as determined i n t h i s 6.2.3  Church's Church  study.  Model  (1973 and 1978 p e r s . comm.) f e l t  that Sustut  copper m i n e r a l i z a t i o n  took p l a c e s h o r t l y a f t e r d e p o s i t i o n o f the Moosevale  f o r m a t i o n and p r e d a t e d  r e g i o n a l metamorphism w h i c h " s e a l e d the i n t e r s t i t i a l  rock p o r e s " .  thermal  The h y d r o -  s o l u t i o n s , w h i c h c a r r i e d the copper and o t h e r i o n s , were a l a t e r  stage  (or d e u t e r i c ) development o f the v o l c a n i s m ( w i t h i n the a r e a ) w h i c h f l o w e d t h r o u g h the r e c e n t l y d e p o s i t e d v o l c a n i c l a s t i c s a l o n g f r a c t u r e channelways  until  impermeable i n t e r b e d s were reached through w h i c h the f l u i d s c o u l d n ' t f l o w . Due t o the stoppage o f f l o w , the copper was then p r e c i p i t a t e d . T h i s p a r t i c u l a r model f a c e s two main p r o b l e m s .  In the f i r s t  the copper m i n e r a l i z a t i o n v i s i b l y c u t s , and thus p o s t d a t e s , o f t h e North Zone. Moosevale  the b a s a l t i c dyke  T h i s dyke was d e f i n i t e l y i n t r u d e d i n t o a l r e a d y c o n s o l i d a t e d  Formation rocks and i s most l i k e l y c o r r e l a t i v e w i t h o t h e r  i n t r u s i o n s which p o s t - d a t e the H a z e l t o n Group. was  instance,  This  basic  i n d i c a t e s t h a t the dyke  i n t r u d e d a f t e r the Lower J u r a s s i c H a z e l t o n Group and t h e r e f o r e the copper  m i n e r a l i z a t i o n i s a t l e a s t o f Lower J u r a s s i c age.  The second problem is  that  the copper and metamorphic m i n e r a l i z a t i o n are i n t i m a t e l y i n t e r g r o w n and appear  180 to have a common g e n e s i s . metamorphic  6,3  A U n i f y i n g G e n e t i c Model  flowed upwards upper Moosevale  f o r Sustut  Copper  Deposit  t o the Model  The w r i t e r b e l i e v e s  until  do not p r e d a t e f o r m a t i o n o f  minerals.  Introduction  6.3.1  The copper m i n e r a l s  through  t h a t copper and s u l p h u r - r i c h  hydrothermal  solutions  permeable passageways, m a i n l y f r a c t u r e swarms,  F o r m a t i o n at the S u s t u t  deposit.  This  i n the  upward f l o w c o n t i n u e d  c e r t a i n permeable i n t e r b e d s w i t h i n the v o l c a n i c l a s t i c sequence were  e n c o u n t e r e d , whereupon  the s o l u t i o n s  With the f l u i d  influx f i l l i n g  f l o w e d upwards  from the i n t e r b e d s  beds were e n c o u n t e r e d  spread  pore space  laterally  the  interbeds.  i n the i n t e r b e d s , the s o l u t i o n s  i n t o o v e r l y i n g host  in which l a t e r a l  through  rock, u n t i l  other  f l o w a g a i n o c c u r r e d . These  in f i g u r e  The f r a c t u r e channelways,  This  t h a t f e d and i n t e r c o n n e c t e d the o r e  The f e e d e r mechanics o f t h e s e v e i n s  l i n e s of evidence. and'ore  lenses.  Most o b v i o u s  As p r e v i o u s l y  below o r e l e n s e s ,  model  82.  a r e r e p r e s e n t e d now by swarms o f t h i n su1phide-gangue v e i n s which cut the p r o p e r t y .  inter-  fluid-filled  i n t e r b e d s a r e now r e p r e s e n t e d by the c h a l c o c i t e - b o r n i t e o r e l e n s e s . i s shown s c h e m a t i c a l l y  then  lenses, through  i s s u p p o r t e d by s e v e r a l  i s the c l o s e s p a t i a l  i n t e r r e l a t i o n of  veins  s t a t e d , i n o u t c r o p o r e v e i n s appear above and  and a r e not apparent w i t h i n o r e l e n s e s . A l s o q u a l i t a t i v e  examination of d r i l l  core reveals  t h a t v e i n m i n e r a l i z a t i o n i s most  significant  below the main o r e h o r i z o n s where l e n s o i d o r e forms become l e s s common and important.  The s t e e p l y d i p p i n g o r v e r t i c a l  c o n s i s t e n t w i t h t h e i r a c t i n g as channelways  nature of the veins f o r deeply derived  is  also  hydrothermal  fluids. The same h y d r o t h e r m a l were a l s o minerals.  responsible This  solutions  from w h i c h the copper  ions  precipitated,  f o r the development o f the open s p a c e - f i l l i n g metamorphic  conclusion  f o l l o w s n a t u r a l l y from the o b s e r v a t i o n s  t h a t the  j^w^REeTiON-tfF OR£^ FLUIDS TABULAR COPPER „  F i g u r e 82: Conceptual model f o r g e n e s i s o f S u s t u t Copper d e p o s i t . The upper diagram shows the d e p o s i t l o c a l i z e d i n a s t r u c t u r a l l y c o n t r o l l e d thermal high t h a t caused a n o d e - l i k e i r r e g u l a r i t y i n t h e r e g i o n a l metamorphic i s o g r a d . The lower diagram i s a h i g h l y i d e a l i z e d i l l u s t r a t i o n o f copper m i n e r a l and p y r i t e z o n i n g w i t h i n a m i n e r a l i z e d t a b u l a r zone. In r e a l i t y , zones o v e r l a p e x t e n s i v e l y . Vertical lines a r e s c h e m a t i c r e p r e s e n t a t i o n o f v e i n swarms. Dominant m i n e r a l s i n zones a r e as f o l l o w s : Cu-native c o p p e r , c c - c h a l c o c i t e , b o - b o r n i t e , cp-cha1 c o p y r i t e , p y - p y r i t e .  182 s u l p h i d e and metamorphic m i n e r a l s a r e i n t i m a t e l y i n t e r g r o w n and thus  appear  to have a common o r i g i n . The i n t e r b e d s w h i c h a r e m i n e r a l i z e d p r e f e r e n t i a l l y have been d e s c r i b e d p r e v i o u s l y as o p t i m a l l y su1 phi d e - m i n e r a l i z e d h o r i z o n s The reason t h a t hydrothermal s o l u t i o n s and no o t h e r s  is because t h e s e  ( s e c t i o n 5-2.4,  flowed l a t e r a l l y through  t h a t where s u l p h i d e - r i c h v e i n s cut impermeable host  interbeds  It s h o u l d be noted  rock, small  gangue-fi11ed  rock c l o s e t o the v e i n , l o c a l l y c o n t a i n s u l p h i d e s .  random n a t u r e and a r e a l e x t e n t s o c c u r because chapter)  levels  i n t e r b e d s had h i g h e r p e r m e a b i l i t i e s than the  o t h e r s u b u n i t s ' W i t h i n the g e n e r a l v o l c a n i c l a s t i c p i l e .  p o r e s , w i t h i n the host  these  above).  (as. s t a t e d i n t h e P r o p e r t y  Their Geology  i n the Moosevale e x i s t as s e p e r a t e f a c i e s w i t h i n a v o l -  c a n i c l a s t i c p i l e made up o f w i d e l y d i f f e r i n g , i n t e r d i g i t a t e d s e d i m e n t o l o g i c a l types. The metamorphic grade o f the d e p o s i t  i s h i g h e r than t h a t o f o t h e r  rocks  a t e q u i v a l e n t s t r a t i g r a p h i c l e v e l s because o f the e f f e c t o f the r i s i n g , hot hydrothermal s o l u t i o n s w h i c h r a i s e d the temperature o f the rocks the s o l u t i o n s  intruded.  The S u s t u t  d e p o s i t can be l i k e n e d to a node o f  r e l a t i v e l y h i g h e r grade metamorphism w i t h i n the r e g i o n a l All  i n t o which  laumontite f a c i e s .  o f the open s p a c e - f i 1 1 i n g metamorphic m i n e r a l s a t S u s t u t  a r e o f the p r e h n i t e -  p u m p e l l y i t e f a c i e s and no z e o l i t e s a r e p r e s e n t . Thus, i f the m i n e r a l i z i n g solutions  caused development o f m i n e r a l s o f the p r e h n i t e - p u m p e l l y i t e f a c i e s ,  then they e f f e c t i v e l y i n c r e a s e d the metamorphic g r a d e .  The r e s t r i c t i o n o f  s i g n i f i c a n t copper o c c u r r e n c e s a n d p r e h n i t e - p u m p e l l y i t e . f a c i e s w i t h i n the upper member o f the Moosevale the f r a c t u r e channelways  F o r m a t i o n to the S u s t u t d i d not e x i s t  t h e r e f o r e f l u i d s c o u l d not b.3.2  Paragenetic  d e p o s i t , may i n d i c a t e t h a t  i n o t h e r a r e a s o f t h i s member and  rise.  Sequence  The s i m p l i f i e d p a r a g e n e t i c sequence f o r the m e t a l l i c m i n e r a l s found on  183 Sustut  i s shown i n f i g u r e 83.  sulphides  M a g n e t i t e and minor h e m a t i t e are p y r o g e n i c .  and n a t i v e copper are hydrothermal  the diagram i n o r d e r o f t h e i r appearance  i n o r i g i n and are r e p r e s e n t e d on appears  here).  d i g e n i t e and a l l o f the c o v e l l i t e are c l a s s i f i e d as supergene  - they  ( h e m a t i t e II  from l a t e r o x i d a t i o n o f p r e - e x i s t i n g s u l p h i d e s . be u n r e l a t e d t o the main m i n e r a l i z i n g 6.3.3  from Other  Deposits  around n a t i v e copper cores was  (with some copper)  solutions  from an i n t e r b e d interbed  can be thought o f as a l o c u s from which m i n e r a l i z i n g s o l u t i o n f r o n t s  advanced  A one-sided the S u s t u t  had o r i g i n a l l y f l o w e d .  caused  The porous  into adjacent country  solutions  resulted  episode.  The z o n a t i o n o f m e t a l l i c s u l p h i d e s  i n t o which hydrothermal  Some minor  T h i s o x i d a t i o n i s assumed to  Causes o f Ore Z o n a t i o n and S i m i l a r Z o n a t i o n s  by outward m i g r a t i o n o f s u l p h u r  The  rock.  zonation with equivalent mineralogical  d e p o s i t , has been d e s c r i b e d by Brown  Copper Deposit o f M i c h i g a n .  15 m above the base o f t h i s u n i t .  (1971) f o r the White P i n e  l e v e l w i t h i n the Nonesuch S h a l e ,  T h i s c h a l c o c i t e d e f i n e s Brown's  6 to  "cuperiferous  to zones o f b o r n i t e , s t a b l e w i t h c h a l c o c i t e , a second  b o r n i t e , not w i t h c h a l c o c i t e , c h a l c o p y r i t e , and f i n a l l y  pyrite.  occurs  is seen i n t a b u l a r  i n the c h a l c o p y r i t e - p y r i t e zones.  at S u s t u t ,  in  In t h i s d e p o s i t , c h a l c o c i t e ( w i t h r a r e n a t i v e  copper) o c c u r s at a d e f i n e d s t r a t i g r a p h i c  z o n e " which grades upwards  changes as those  This zonation  Greenockite zones  b u t . t h e z o n a t i o n o c c u r s both above and below the c e n t r a l copper c o r e .  Brown v i s u a l i z e s  the White P i n e d e p o s i t  an "upward a d v a n c i n g m i n e r a l i z a t i o n f r o n t copper-rich solutions lying areas.  progressively  (and z o n a t i o n )  as the product o f  ( f r i n g e ) " caused by the m i g r a t i o n of  up through the Nonesuch  Formation from under-  The p y r i t e of the Nonesuch p r e d a t e s copper m i n e r a l i z a t i o n , thus  Brown says the copper p r e c i p i t a t e d around and r e p l a c e d the o r i g i n a l Brown s t a t e s  pyrite.  t h a t the upward m i g r a t i o n of the f l u i d s c o u l d c o n c e i v a b l y be  e x p l a i n e d by e i t h e r ' d i f f u s ion or i n f i l t r a t i o n mechanisms.  The u l t i m a t e s o u r c e  of the copper "may l i e i n primary magmatic c o n t r i b u t i o n s or e x t r a c t i o n of m e t a l s  Pyrogen ic  Supergene  Hydrothermal  Magnetite Hematite Native  Copper  Chalcocite Digenite  J  Bornite Charcopyr ite Greenockite Pyrite j  C cve i I ite  F i g u r e 83:  S i m p l i f i e d p a r a g e n e t i c m i n e r a l sequence f e n c e diagram f o r S u s t u t  Copper o r e s .  j  185 from the t h i c k v o l c a n i c - s e d i m e n t a r y p i l e o f the Keweenawan bas i n" ( i b i d . , p. Robertson minerals  (1975) has d e s c r i b e d a s i m i l a r z o n i n g p a t t e r n ' o f m e t a l l i c  in the Mount Bohemia d e p o s i t o f M i c h i g a n .  o r i g i n of t h i s deposit solutions  Robertson's  f l o w tops and broken dyke m a r g i n s "  ( i b i d . , p. 1202).  into b o r n i t e that occurs  n e a r e s t c h a l c o c i t e , whereas  i n two f o r m s .  r e l a t i v e l y permeable  The z o n a t i o n e x i s t s  c h a l c o c i t e , n e a r e s t the i n f i l t r a t i o n p o i n t o f s o l u t i o n s  chalcopyrite.  model f o r the  i n v o l v e s upward movement o f c o p p e r - r i c h hydrothermal  a l o n g f r a c t u r e s and then movement " o u t w a r d a l o n g  w h i c h grades  543).  as  i n t o permeable l e v e l s ,  A c o p p e r - r i c h b o r n i t e forms  f u r t h e r o u t w a r d , a b o r n i t e forms w i t h some e x s o l v e d  C h a l c o p y r i t e o c c u r s n e x t , and f i n a l l y p y r i t e makes an appearance  as the outermost s u l p h i d e .  Robertson a s c r i b e s  the z o n a t i o n to e i t h e r ; a  s o l u t i o n o f c o n s t a n t c o m p o s i t i o n g r a d u a l l y m i g r a t i n g through the host  rocks and  p r e c i p i t a t i n g s u l p h i d e m i n e r a l s as c o n c e n t r a t i o n and redox r e l a t i o n s p e r m i t t e d ; o r t o a s o l u t i o n o f changing  c o m p o s i t i o n through t i m e , w h i c h f i r s t d e p o s i t e d  p y r i t e , changed c h e m i c a l l y and r e a c t e d w i t h some o f the p y r i t e and produced chalcopyrite, etc., until  c h a 1 c o c i t e was produced as the f i n a l  Brown (1974) conducted p r e c i p i t a t i o n chromatography Zn-Pb s o l u t i o n s ation  product.  e x p e r i m e n t s on Cu-Cd-  i n o r d e r t o d e t e r m i n e the s i g n i f i c a n c e o f g r e e n o c k i t e m i n e r a l i z -  i n c h a l c o p y r i t e - p y r i t e zones o f the White P i n e d e p o s i t  found t h a t when such a s o l u t i o n was pumped i n t o a s i l i c a  (as a b o v e ) .  g e l , CdS  He  (greenockite)  always p r e c i p i t a t e d b e f o r e , and advanced ahead o f , copper s u l p h i d e s .  This  i n d i c a t e s t h a t the g r e e n o c k i t e has a g r e a t e r m o b i l i t y than the copper  sulphides  and " c a n be a p p a r e n t l y d i s p l a c e d o v e r s i g n i f i c a n t d i s t a n c e s by r a p i d i n f i l t r a t i o n of s o l u t i o n s sulphides)"  c o n t a i n i n g metal (ibid., p  c  274).  ions o f l e s s m o b i l e metal s u l p h i d e s  ( i e . Cu  G r e e n o c k i t e i s found in the c h a l c o p y r i t i c zones  b o t h above and below the c o r e s o f o r e h o r i z o n s a t S u s t u t ,  and would seem to have  formed from an a d v a n c i n g f l u i d f r o n t t h a t preceded copper s u l p h i d e s w h i c h are s y m m e t r i c a l l y arranged behind g r e e n o c k i t e i n the o r e This w r i t e r t h e r e f o r e suggests f o r Sustut,  horizons.  t h a t z o n a t i o n around the c e n t r a l  186 l o c i o f c h a 1 c o c i t e - n a t i v e copper cores same hydrothermal  solutions  The w r i t e r b e l i e v e s  t h a t d e p o s i t e d t h e c o r e s , as advancing  t h e z o n a t i o n was caused by p r o g r e s s i v e  be d e s c r i b e d b e l o w ) .  fluid  fronts.  chemical changes ( t o  G r e e n o c k i t e i s found i n f a c t t o be at t h e head o f t h e  f r o n t , ahead o f t h e copper s u l p h i d e s , have  i s due t o outward m i g r a t i o n , o f the s e l f -  as e x p e r i m e n t s by Brown (1974) would  suggested.  6.3-4 C h e m i s t r y o f P r e c i p i t a t i o n To p r e c l u d e d i s c u s s i o n  o f p r e c i p i t a t i o n m e c h a n i c s , as many p h y s i c a l and  chemical c o n s t r a i n t s  as p o s s i b l e  should be p l a c e d on t h e o r e - f o r m i n g  The pH o f the system  i s taken as b e i n g near n e u t r a l because c a l c i t e  system. is i n t e r -  grown e x t e n s i v e l y w i t h the m e t a l l i c m i n e r a l s . The Cu ions were C u and they +  were i n c h l o r i d e complexes as C u C ^ ( t h e s e forms a r e t h e most w i d e l y a c c e p t e d modes o f t r a n s p o r t o f Cu i n hydrothermal all  solutions,  this  copper ions a r e i n t h e +1 s t a t e , o r t h a t a l l copper  i s not t o suggest t h a t ions a r e complexed  s o l e l y by c h l o r i d e i o n s , but f o r t h e sake o f a q u a l i t a t i v e a n a l y s i s f o r m i n g c h e m i s t r y , some s i m p l i f y i n g assumptions pH v s . l o g f g  are necessary).  diagram w i t h the major aqueous s u l p h u r  and 1 b a r p r e s s u r e .  of o r e -  F i g u r e 84 i s a  s p e c i e s p r e s e n t a t 300'C  (300'C i s an a c c e p t a b l e t e m p e r a t u r e as a l l i n d i c a t i o n s show  the t e m p e r a t u r e o f f o r m a t i o n o f the d e p o s i t was i n t h i s  neighbourhood  ( i e . 300  t o 400°C) , thermodynamic d a t a f o r t h i s S system i s o f poor q u a l i t y above 300*C and 1 b a r p r e s s u r e ) . 5.73.  Neutral  pH at 306'C, from Barnes e t a l . (1966), i s about  The breakdown o f m a g n e t i t e t o h e m a t i t e o c c u r s  (Helgeson  at a log f^  o f about -30.00  e t a l . , 1969), t h i s puts a c o n s t r a i n t on t h e oxygen f u g a c i t y o f t h e  s o l u t i o n as m a g n e t i t e d i s s o l v e d and h e m a t i t e p r e c i p i t a t e d w i t h the onset o f o r e m i n e r a l i z a t i o n . Thus, from f i g u r e 84, the dominant s u l p h u r the o r e - f o r m i n g s o l u t i o n s , pH o f 5.73 and l o g f  species  present  a t the o u t s e t , would have been HSO^ ( u s i n g  in  a starting  o f g r e a t e r than -30.00) . 2  The i n i t i a l reducing)  hydrothermal  s o l u t i o n s were more o x i d i z i n g  and more c o p p e r - r i c h than t h e host  rocks  (and t h e r e f o r e  they i n v a d e d .  This  is  less  187  o o  to _ I  5.7  o  OD. I  0.0  A.D  2.0  F i g u r e 8k: Log f -  PH  8.0  12.0  lff.O  vs_. pH diagram o f t h e dominant aqueous s u l p h u r 2  14.0  species  a t 300"C and 1 bar p r e s s u r e . T h i s i s a computer-generated f i g u r e . Initial c o n t r a i n t s on f l u i d c o m p o s i t i o n a r e pH o f 5.7 and l o g f . o f -30.00. 2  188 s h o w n by  the breakdown  hematite,  and o f  of  course,  of wall  r o c k and  nature  (j_e. t h e f .  pyrogenic  magnetite with  the p r e c i p i t a t i o n of  f l u i d progressed, decreased  though,  and  the  f_  2 pyrite  formed as  b  a final  The z o n a t i o n  product  described  and c h a l c o c i t e f o r m a t i o n was precipitation. and  ions  to  the s o l u t i o n .  precipitated  as  hematite.  and c h a l c o c i t e same g e n e r a l  species and  form of  the f l u i d s  not  1 )  is  with  not  in the s o l u t i o n . be c o n s t r u e d  the  2 C u C 1  the copper  Oxidation  2(aq)  (19&9)  copper +  2  *  magnetite  A q u e o u s HCI t h e pH o f  the  that  copper  breaking  shows  copper  minerals,  magnetite  down and  releasing  f e r r i c state native  Cuprite  native  and  copper,  hematite  cuprite  II  precipitation reactions  stepwise  Thus,  the o n l y ,  in  the  and w r i t t e n s u c h  and w a l l  rock  that  be  necessarily  Components  the supposed  a guide  as  pre-  consistency  maintained.  use o n l y  they are o n l y o r even  is  will  t o what  correct,  major happens  reactions  H  2° *  p r e c i p i t a t e d f i r s t , : t h e r e a c t i o n c a n be v i e w e d 2  C  U  +  within  the  2 H C 1  (aq)  +  2 C 1  the s o l u t i o n  (aq)  and  as:  *°2  +  t h e r e f o r e most  likely  combines  as:  CuO to hematite would also  was w r i t t e n as  the s o l u t i o n  described  as  to form c u p r i t e  Cu + J f 0 of  such  system.  a c t u a l l y present  2)  these  c r e a t e d a r e q u a l i t a t i v e l y c o r r e c t but  present  in  in  formed f i r s t .  with  intergrown with  the p r o g r e s s i v e  nature of  Assuming n a t i v e  0^  and c h a l c o c i t e  the changing  occuring  copper  in the o x i d i z e d  are  should  native  rocks were  i r o n was  reactions  or  reaction  reduced  in the s o l u t i o n )  penecontempouraneous  These  destroyed  the  reactions.  the host  The  As  of  areas.  below.  between  increased  the formation of  of  minerals.  f l u i d became more  The o r e m i n e r a l o g r a p h y  intergrown,  The g e n e r a l sented  the  indicates  almost  silicates  copper  formation  2  the  above  Coincident with  ferro-magnesiurn  iron  of  resultant  and  log'of  not  a  lower  product it.  use in  This  the d i s s o c i a t i o n  some o f  reaction is  t h e 0^ f r o m 1 in order  reaction  to  p a r t i a l l y c o r r e c t as  constant,  at  300"C,  f o r HCI  buffer Helgeson as  1.  ,  189 being -1.24 which  i n d i c a t e s a K o f .0575, meaning (H ) +  than p r o d u c t s  the product H  t h a t the a c t u a l H additions  +  and CI  stable  (CI")  (_i_e. K = — ( n C l ) —  thus c o u l d cause  r e a c t a n t s a r e more  ^' +  P  r o <  ^  u c t  '  ° ^ excess  o n  to r e a c t and c r e a t e HC1.  CI  in the s o l u t i o n  It s h o u l d be noted  c o n t r i b u t i o n t o t h e s o l u t i o n would be very  to t h e f l u i d s c o n t e n t o f these  minor  ions and any HC1 p r o d u c t i o n i s a c t u a l l y  neglig ible. P r o d u c t i o n o f n a t i v e copper and c u p r i t e e f f e c t i v e l y decreased t h e f i n c r e a s e d t h e f_ 2  t o t h e e x t e n t t h a t c h a l c o c i t e f o r m a t i o n became s t a b l e .  and 2 This  b  p r o d u c t i o n of c h a l c o c i t e occured at nearly  t h e same time as t h a t o f n a t i v e  and c u p r i t e and o c c u r e d w i t h the o x i d a t i o n and p r e c i p i t a t i o n o f i r o n ions h e m a t i t e 11) the host  rock.  3) however 0 less  introduced This  2CuCl2  ( a q )  copper (as  i n t o the s o l u t i o n by breakdown o f p r i m a r y m i n e r a l s  in  r e a c t i o n c o u l d have gone a s : HS0-  +  ( a q )  * Cu S 2  +  HC1  ( a q )  +  Cl^  3  q  )  +  20  2  c o u l d not a c t u a l l y be a phase w i t h i n t h e system ( i e . t h e l o g f ^  than - 2 0 ) .  In i t s p l a c e m a g n e t i t e would be o x i d i z e d t o h e m a t i t e .  is  Reaction 3  w o u l d then a c t u a l l y b e : 4) Reactant  2CuCl~, » + HS07, » + 8Fe,0. 2(aq) 4(aq) 3 ^ iron content  +  C u  o 2 s  i n 4 ( w r i t t e n as m a g n e t i t e )  i r o n would be c o n t r i b u t e d from s i l i c a t e s .  As t h i s  would move away from n a t i v e copper s t a b l e f u r t h e r This  progression  decrease  in f  changes the s o l u t i o n c h e m i s t r y and i n c r e a s e  n  i n f_ .  2  sulphur  between s u l p h u r -29  to -30.  species  reached.  i s m a i n l y s c h e m a t i c as some r e a c t i o n progressed i n t o the c h a l c o c i t e  the system field.  f u r t h e r as i l l u s t r a t e d by a  As t h e s o l u t i o n changed the b o r n i t e s t a b i l i t y Coupled w i t h a d e c r e a s e  i n s o l u t i o n changed  slowly.  phases HSO^ and h^S, a t n e u t r a l  i n the f - , t h e °2  F i g u r e 84 shows e q u i l i b r i a  pH, o c c u r s  in a l o g f g  W i t h t h e onset o f b o r n i t e s t a b i l i t y , some H S was p r o b a b l y 2  in t h e r e a c t i o n as a major s u l p h u r to h e m a t i t e  II  12Fe„0. 2 3  2  f i e l d would be e v e n t u a l l y dominant  + HC1, x + 3C1T \ + (aq) (aq)  species.  M a g n e t i t e was s t i l l  range o f involved  being o x i d i z e d  d u r i n g b o r n i t e p r e c i p i t a t i o n , as shown by m i n e r a l o g r a p h i c  inter-  190  growths o f b o r n i t e and h e m a t i t e 5 )  5 C u C ,  2(aq)  +  F e  (aq)  +  II.  2HS0  The b o r n i t e f o r m a t i o n can be v i s u a l i z e d  iV<aq)  +  2 H  2 (aq) S  Cu FeS 5  A  +  l 6 F e 3  +  °<.  10Cl"  as:  * + 24Fe 0  a q )  2  3  6 |  +  H  a q )  T h i s r e a c t i o n is a c t u a l l y the i n t e r m e d i a t e one i n the f o r m a t i o n of '  bornite.  B o r n i t e has an e x t e n s i v e s o l i d s o l u t i o n f i e l d .  Bornite  I (the  r i c h v a r i e t y ) would have more copper than s t o i c h i o m e t r i c Cu^-FeS^. t y p e was the f i r s t formed o f the b o r n i t e s  and as p h y s i o - c h e m i c a l  t a k i n g p l a c e w i t h i n the s o l u t i o n , the b o r n i t e s r i c h and c o p p e r - p o o r  (ie. bornites  f o r m i n g , HSO^ was p r o b a b l y s t i l l  This  When the b o r n i t e  the main s u l p h u r  species  bornite  changes were  became p r o g r e s s i v e l y  l l a and l i b ) .  more  iron-rich).  bornites  (the i r o n - r i c h o n e s ) ,  H^S  ( i e . as the  When the s o l u t i o n began p r e c i p i t a t i n g the l a s t o f  bornites  the  the redox r e l a t i o n s of the r e a c t i o n changed  t h a t o x i d a t i o n o f H^S became more important than o x i d a t i o n o f m a g n e t i t e . i s shown i n the m i n e r a l o g r a p h y bornite  as h e m a t i t e i s  I and l e s s commonly w i t h b o r n i t e s  i n t e r g r o w n most commonly  the s o l u t i o n  a f- -f_ s t a t e w h e r e i n the c h a l c o p y r i t e s t a b i l i t y f i e l d was e n t e r e d . 2 2 i n d i c a t e s t h a t the copper  r e l a t i v e t o t h a t i n the o r i g i n a l probably occured •  6 )  C u C 1  H^S  solution.  such This  with  l l a and l i b .  With p r e c i p i t a t i o n o f the most i r o n - r i c h b o r n i t e s ,  p r e c i p i t a t ion o f c h a l c o p y r i t e  started  With p r o -  g r e s s i v e decrease, in the o x i d i z i n g n a t u r e of the f l u i d s , the amount of  became  iron-  I first  in solution.  i n c r e a s e d and the o x i d a t i o n o f m a g n e t i t e to hematite slowed  copper-  entered The  ion c o n t e n t had  The c h a l c o p y r i t e  decreased  precipitation  as:  2(aq)  +  F e  Uq)  +  i s now the dominant  system a t t h a t p o i n t .  2 H  2 (aq)  *  sulphur  species  S  Iron is p r e s e n t  in  C u F e S  2  +  Kaq)  +  2 C 1  (aq)  due to o x i d a t i o n s t a t e o f  the  the f e r r i c s t a t e though as the f  is °2  such t h a t f e r r o u s  i r o n is not s t a b l e .  which p y r i t e becomes s t a b l e . state.  F i n a l l y the s o l u t i o n  At t h i s p o i n t the s o l u t i o n was  T h i s r e a c t i o n can be viewed  as:  reaches a s t a g e i n i t s most  in  reduced  191 2Fet  7)  + +  ,  (aq) In e f f e c t ,  + 2H S, v 2 (aq)  Z  0  FeS. + kH . , + F e t v 2 (aq) (aq) +  +  f e r r i c i r o n i s reduced  in t h i s  r e a c t i o n 7 to ferrous  iron.  The i n c r e a s e i n t h e f e r r o u s  i r o n c o n t e n t c o u l d c o n c e i v a b l y have caused the  precipitation of c h l o r i t e .  T h i s would e x p l a i n t h e e x t e n s i v e  p y r i t e w i t h ch1 o r i t e .  intergrowth of  Thus the s o l u t i o n has changed p r o g r e s s i v e l y  from an  o x i d i z i n g nature to a reducing one. F i g u r e 85 i s a l o g f_ U  vs_. l o g f^  2  b  d i a g r a m , a t 300*C and 1 b a r p r e s s u r e ,  2  w i t h the s t a b i l i t y f i e l d s o f a l l r e l e v a n t phases i n the Cu-Fe-S-0 system represented.  The p r o g r e s s i v e  1 - 7, d e s c r i b e s a s t r a i g h t  r e a c t i o n p a t h , as s u g g e s t e d above  i n the e q u a t i o n s  l i n e path from n a t i v e c o p p e r - c u p r i t e s t a b l e , i n t h e  h e m a t i t e r e a l m , t o p y r i t e s t a b l e i n t h e h e m a t i t e realm ( i e . from A t o B on t h e figure). also  The s t a b i l i t y r e l a t i o n s o f g r e e n o c k i t e (CdS) and monteponite (CdO) a r e  r e p r e s e n t e d on t h i s d i a g r a m .  determined using  (The r e l a t i o n s o f t h e s e two phases were  the d a t a o f Robie e t a l . (1978) ).  The CdS-CdO e q u i l i b r i u m l i n e  i s o n l y approximate as t h e thermodynamic data f o r t h e s e two m i n e r a l s a r e not o f high q u a l i t y .  However,  i t i s apparent t h a t CdS i s s t a b l e through a l l p a r t s o f  the r e a c t i o n path f o r t h e s u l p h i d e m i n e r a l s .  S i n c e g r e e n o c k i t e i s found o n l y  w i t h c h a l c o p y r i t e , a t i t s time o f p r e c i p i t a t i o n the dominant s u l p h u r s p e c i e s was H S. 2  The p r e c i p i t a t i o n p r o b a b l y o c c u r r e d a s : 8)  CdCl-  3 ( a q )  +  H S 2  ( a q )  *  CdS  +  2 ; H  a q )  +  3Cl"  a q )  The p r e s c e n c e o f g r e e n o c k i t e w i t h c h a l c o p y r i t e may i n d i c a t e t h a t t h e CdCI^  c o n t e n t was low enough t h a t s u l p h u r s p e c i e s  not s u l f a t e ) was n e c e s s a r y  i n t h e form o f H S ( i e . s u l f i d e , 2  i n o r d e r t o p r e c i p i t a t e ( ? e . H S becomes 2  w i t h i n the c h a l c o p y r i t e s t a b l e r e g i o n ) .  dominant  T h i s may be i n f l u e n c e d by the f a c t t h a t  CdS p r e c i p i t a t i o n from HSO^ would i n v o l v e a r e l e a s e o f C> which c o u l d not have 2  o c c u r e d as i n d i c a t e d by t h e low f^ t h i s stage.  This hypothesis  c o n d i t i o n s o f t h e s o l u t i o n and host  rocks a t  i s more r e a s o n a b l e than B r o w n ' s (1974) s u g g e s t i o n  t h a t g r e e n o c k i t e o c c u r r e d outermost  i n an advancing  f l u i d f r o n t due t o the  192  T  =  300°C  P  Tenortt©  -10  Cuprite  +  +  =  rs  Q I  \  i  Q. I  i  i  Hemott  H em o 1 1 1 e  cr o Copper  LU  «  -30  +  Henioti  X  o cr  o ppe r  o  Copper  Ff  T + F  Jo "C "D  -50H Copper  +  i  r on  9  Q.  CJ  -60 -50  T  40 LOG  T -30  fl  T  (SULFUR  -20  i  a (J  i  M a  -10 I  GflS)  c CD  Figure 85:  Log f .  - log f . 2  and 1 b a r p r e s s u r e .  diagram f o r t h e Cu-Fe-Cd system a t 3 0 0 ' C 2  This  i s a computer-generated f i g u r e .  path f o r p r e c i p i t a t i o n o f m e t a l l i c m i n e r a l s from A t o B on t h i s diagram. hydrothermal wall  rock.  solutions  i n the Sustut  A i s t h e supposed  and B the f i n a l  initial  The r e a c t i o n deposit  runs  composition of  composition a f t e r reaction with  Phase a b b r e v i a t i o n s a r e t h e same as i n f i g u r e 80.  CdO; g r e e n o c k i t e , CdS; cadmium, Cd; m a g n e t i t e , Mt.  Monteponite,  193 g r e a t e r m o b i l i t y o f Cd 6.3.5  ions.  S i g n i f i c a n c e o f M i n e r a l Zoning The r e a c t i o n path d e s c r i b e d  ideal  i n R e l a t i o n to Changing  Chemistry of  in f i g u r e 85 e x a c t l y c o r r e s p o n d s  to the  z o n a t i o n o f the m e t a l l i c m i n e r a l s w i t h i n the S u s t u t o r e body.  o r i g i n o f the o r e l e n s e s and t h e i r z o n a t i o n s hydrothermal  Solution  Thus the  can be p o s t u l a t e d as f o l l o w s ; the  s o l u t i o n s which f l o w e d i n t o optimum o r e h o r i z o n s were much more  o x i d i z i n g than the host rocks  ( i n f a c t the h o s t s were r e l a t i v e l y r e d u c i n g ) .  Upon f l u i d i n f l u x , t h e s o l u t i o n s and w a l l  rock began to r e a c t i n o r d e r t o a t t a i n  an e q u i l i b r i u m between the d i f f e r i n g o x i d a t i o n s t a t e s . and m a g n e t i t e were broken down i n the host p r e c i p i t a t e d from s o l u t i o n .  Ferro-magnesiurn  silicates  rocks and n a t i v e copper w i t h c u p r i t e  C h a l c o c i t e then began p r e c i p i t a t i o n as  o x i d a t i o n s t a t e was lowered i n the s o l u t i o n  (and f .  the  was e f f e c t i v e l y i n c r e a s e d ) . 2  The s o l u t i o n was thus p r o g r e s s i v e l y  changing.  A l o n g w i t h p r e c i p i t a t i n g copper m i n e r a l s , the s o l u t i o n began to m i g r a t e outwards  from i t s  locus of  i n f l u x into surrounding  country rock.  When c h a l c o c i t e -  n a t i v e c o p p e i — c u p r i t e p r e c i p i t a t e d w i t h metamorphic m i n e r a l s w i t h i n the c o r e s o f the o r e z o n e s , the c h e m i c a l l y changed s o l u t i o n r e a c t e d w i t h f r e s h w a l l away from the c o r e s .  T h i s s o l u t i o n was s t i l l  rock  o x i d i z i n g r e l a t i v e to the host  r o c k s , e x c e p t the s o l u t i o n had changed such t h a t c o p p e r - r i c h b o r n i t e s t a r t e d to precipitate.  T h i s outward m i g r a t i o n o f c o n t i n u a l l y changing s o l u t i o n  which reacted w i t h f r e s h w a l l tion of sulphide minerals. p o i n t i n the host,  r o c k , caused p r o g r e s s i v e ,  compositions  differential precipita-  When the s o l u t i o n reached i t s maximum i n f i l t r a t i o n  i t had a c h i e v e d a r e d u c i n g s t a t e a l m o s t l i k e t h a t o f  c o u n t r y rock (j_e. c o u n t r y rock f  - f U  2  the  c o m p o s i t i o n was near B on f i g u r e b  and the most reduced s u l p h i d e , p y r i t e , was p r e c i p i t a t e d .  At t h i s p o i n t copper  had been e f f e c t i v e l y removed from s o l u t i o n , as had cadmium and most l i k e l y metals  85)  2  other  ( i e. when C d C l ^ was removed from s o l u t i o n in the c h a l c o p y r i t e f i e l d where  sulphide sulphur  species  (_i_e.H S) was dominant, o t h e r t r a c e metals ?  could  194 c o n c e i v a b l y have been drawn o u t o f s o l u t i o n w i t h t h i s s u l p h u r change).  Thus i n  the end t h e s o l u t i o n had a c h i e v e d a redox s t a t e e q u i v a l e n t t o t h a t o f the host rocks such t h a t e q u i l i b r i u m was reached and the s o l u t i o n was a l s o d e p l e t e d i n aqueous metal complexes. The i d e a l z o n a t i o n p a t t e r n i s , a t b e s t , i r r e g u l a r l y developed i n t h e Sustut deposit. f l u i d and w a l l  The i r r e g u l a r i t i e s c o u l d be caused by i n c o m p l e t e r e a c t i o n o f rock,  impermeable l a y e r s through which s o l u t i o n s c o u l d not f l o w  and thus had to r e a c t i n a s i n g l e a r e a , o r s m a l l e r c o n c e n t r a t i o n s of  influxing solutions  r e l a t i v e to the host  (or amounts)  rock.  Areas such as those c u t by DDH's 25 and 132, tend t o i n d i c a t e t h a t t h e r e is a broad p y r i t i c h a l o t o t h e whole upper Moosevale ore lenses.  This  i s c o n c e i v a b l e as s o l u t i o n s  Formation t h a t c o n t a i n s the  f u r t h e s t from t h e i r source  loci  would p r e c i p i t a t e p y r i t e , thus the broad h a l o c o u l d be a r e s u l t o f t h e most o u t ward m i g r a t i o n o f hydrothermal s o l u t i o n s tration  (J_e_. the upper  from a complete a r e a o f copper c o n c e n -  Moosevale).  6.4 U l t i m a t e O r i g i n o f Hydrothermal  Fluids  The o r i g i n o f t h e hydrothermal s o l u t i o n s  i s p r o b l e m a t i c a l as not enough  data were gathered on t h e rocks d i r e c t l y u n d e r l y i n g the d e p o s i t to deal d i r e c t l y w i t h t h i s problem.  Sulphur  isotope analyses  c o u l d shed some l i g h t on the o r i g i n  o f the s u l p h u r , but u n f o r t u n a t e l y these a n a l y s e s were not completed i n time f o r this thesis. o f rocks  The h i g h background copper c o n t e n t s o f t h e whole r e g i o n a l  sequence  ( i n c l u d i n g the A s i t k a Group), suggest t h a t a mechanism which leached  copper v a l u e s from the host  rocks c o u l d have l e d t o c o n c e n t r a t i o n and p r e c i p i t a t i o n  h i g h e r up i n the sequence.  This  (1974) models. mode o f o r i g i n .  is a g e n e r a l i z a t i o n of Harper's  Problems a r i s e when a s s i g n i n g  (1977) and J o l l y ' s  the hydrothermal f l u i d s t o t h i s  In the f i r s t p l a c e t h e r e does not seem t o be any g r e a t d e p l e t i o n  i n copper c o n t e n t s on t h e p r o p e r t y and no area w i t h i n the r e g i o n has had such a d e p l e t i o n r e p o r t e d by o t h e r s .  195 A second q u e s t i o n Neither J o l l y  i s where d i d the aqueous s u l p h u r s p e c i e s come f r o m .  (1974) nor Harper  (1977) have suggested how the v a s t q u a n t i t y o f  s u l p h u r c o u l d have been d e r i v e d from host average s u l p h u r 240 ppm. sulphur  content of basalts  (1972) s t a t e s  that  i s about 300 ppm and o f sandstones i s about  S i n c e most o f the T a k l a Group i s v o l c a n i c l a s t i c i n n a t u r e , a background c o n t e n t can be a s s i g n e d o f between 240 and 300 ppm.  Keweenawan b a s a l t s ,  the average  Group, however as J o l l y tion.  rocks. Turekian  s u l p h u r c o n t e n t would be above t h a t o f t h e T a k l a  (1974) s t a t e d t h e r e was no e v i d e n c e o f s u l p h u r m o b i l i z a -  Evidence f o r b i o g e n i c o r i g i n o f s u l p h i d e  area o f S u s t u t .  In t h e case o f the  is totally  l a c k i n g i n the regional  S h a l e s a r e a v e r y minor p o r t i o n o f t h e sequence.  Another s i g n i f i c a n t problem w i t h i n s i t u d e r i v a t i o n , i s t h e d i f f e r e n t o x i d a t i o n s t a t e s o f t h e s o l u t i o n and the c o p p e r - h o s t  T a k l a Group.  Group rocks had a low o x i d a t i o n s t a t e as shown by a l o g f p hydrothermal  solutions  had a h i g h e r o x i d a t i o n s t a t e  It i s i m p o s s i b l e  >-25.00.  The T a k l a  o f <~30.00.  The  i n d i c a t e d by a l o g f g  to derive a f l u i d w i t h a higher o x i d a t i o n state  of than  the p a r e n t . T h i s w r i t e r does not w i s h t o t o t a l l y of metamorphically derived f l u i d s solutions  from w h i c h the S u s t u t  non-basaltic ore f l u i d . f o r example.  source  (from the T a k l a Group)  t o produce t h e n e c e s s a r y  contribution  t o t h e hydrothermal  Copper Deposit was p r e c i p i t a t e d .  is essential  Presumably  r u l e o u t the p o s s i b l e  However, a  oxidation state o f the  such a f l u i d c o u l d be d e r i v e d from an u n d e r l y i n g  No such i n t r u s i o n ( o r i n t r u s i v e s u i t e )  intrusion,  has been found i n l o c a l  mapping and may o n l y be e x t a n t a t g r e a t d e p t h .  6.5  Possible  The S u s t u t thermal  Prospecting  Tools  Copper D e p o s i t o f f e r s a unique o p p o r t u n i t y  copper o c c u r a n c e  to study a h y d r o -  ( o f economic p o t e n t i a l ) t h a t has not undergone  d e f o r m a t i o n o r p o s t - o r e metamorphism.  Therefore  i t i s more o r l e s s  strong  i n t h e same  form as a t t h e t i m e o f f o r m a t i o n . For t h i s reason g e n e r a l i z a t i o n s , based on a  196 mode o f f o r m a t i o n , c o u l d be used i n o r d e r to l o c a t e another d e p o s i t o f s i m i l a r type. If  the T a k l a rocks had a g e n e r a l l y u n i f o r m p e r m e a b i l i t y  concentration of sulphides  may not have o c c u r e d as the s u l p h i d e s would have  been d i s s e m i n a t e d through the h o s t .  Thus the most o b v i o u s  would be a t h i c k sequence o f v o l c a n i c l a s t i c (or v o l c a n i c ) s e p e r a t e and d i s t i n c t i n t e r b e d s  (or f a c i e s )  i t i e s and p o r o s i t i e s due t o amygdules, faceous u n i t s , e t c .  If  throughout,  f e a t u r e to look f o r rock which c o n t a i n s  t h a t have v i s i b l y d i f f e r e n t p e r m e a b i l -  f l o w t o p s , f r a c t u r e z o n e s , porous t u f -  such a s t r a t i g r a p h i c sequence  i s found, f o l l o w - u p  i n v e s t i g a t i o n s h o u l d n a t u r a l l y i n v o l v e d e t a i l e d e x a m i n a t i o n f o r small o f s u l p h i d e - b e a r i n g host  rock.  These  lenses may be o f small enough e x t e n t t h a t  they c o u l d be missed by r e c o n n a i s s a n c e mapping helpful  central  (as  indeed S u s t u t was).  c l u e i s the appearance o f w i d e l y d i s p e r s e d g r a i n s  through such a p i l e .  lenses  I n . t h e case o f S u s t u t ,  Another  of p y r i t e scattered  t h i s p y r i t e i s an e n v e l o p e around  copper-rich areas. A n o t h e r method o f p r o s p e c t i n g would i n v o l v e mapping o f r e g i o n a l m e t a -  morphic f a c i e s and l o o k i n g f o r the source and a p o s s i b l e d r i v i n g f o r c e f o r the development o f t h e metamorphic m i n e r a l s . t o some s o r t o f  rock should be examined c a r e f u l l y f o r i n t r o d u c e d  s u l p h i d e - b e a r i n g v e i n l e t s c r o s s - c u t t i n g a host  would a l s o be i n d i c a t i v e o f p o s s i b l e host  t o be due  i n t r u s i v e , and i f permeable zones a r e p r e s e n t w i t h i n t h e host  r o c k s , then the host Small  If the metamorphism appears  sulphides.  rock a t s t e e p  l e n s o i d c o n c e n t r a t i o n s of s u l p h i d e .  rock i n t h i s case s h o u l d be looked a t f o r p o s s i b l e porous zones  angles The  intersected  by these v e i n l e t s . 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S u r v . Can.,Paper 7 4 - 1 , P t . , A, pp. 19-20.  The T r i a s s i c T a k l a Group i n McConnel1 Creek Map-Area, B r i t i s h C o l u m b i a . G e o l . S u r v . C a n . , Paper 76-29, 4 5 p . .  Morimoto, N., G r i e g , J.W., Tunnel 1, G., 1960. Re-examination of a B o r n i t e from the Carn Brea Mine, C o r n w a l l . C a r n e g i e I n s t . Wash. Year Book 59, pp. 122-126. Morimoto, N., and K u l l e r u d , G., 1961. v. 46, pp. 1270-1282. Parsons,  Polymorphism i n B o r n i t e .  Am. M i n . ,  W.H., 1969C r i t e r i a for Recognition of Volcanic Breccias: G.S.A. Mem. 115, pp. 263-304.  Review.  200 Pel 1y, D o , 1974. P e t r o l o g y and P o s s i b l e Genesis o f the Red and Green C o l o u r a t i o n s in the T a k l a V o l c a n i c s , McConnell Creek Map Sheet, N o r t h - C e n t r a l B r i t i s h C o l u m b i a . Unpub. BASc T h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 23p.. P e t t i J o h n , F . J . , ' 1 9 75 - Sedimentary Rocks. P u b l i s h e r s , New Y o r k , 6 2 8 p „ .  3rd e d i t i o n , Harper and Row  P h i l l i p s , W.R.,1971. M i n e r a l O p t i c s , P r i n c i p l e s and T e c h n i q u e s . W.H. Freeman C o . , San F r a n c i s c o , , 249p.. Ramage,  D.R., 1974. S t r a t i g r a p h y and P e t r o l o g y o f a P y r o c l a s t i c S u c c e s s i o n o f the T a k l a - H a z e l t o n Group, N o r t h - C e n t r a l B r i t i s h C o l u m b i a . Unpub. BSc T h e s i s , U n i v e r s i t y o f B r i t i s h C o l u m b i a , 97p.»  Read, P.B., and E i s b a c h e r , G . , 1973R e g i o n a l Z e o l i t e A l t e r a t i o n o f the S u s t u t Group, B r i t i s h C o l u m b i a . A b s t . o f paper p r e s e n t e d a t Annual Meeting o f the C o r d i l l e r a n S e c t i o n o f the G.A.C.. R i c h t e r , D.A., and Roy, D „ C , 1974. Sub-Greenschi s t Metamorphic in N o r t h e r n Maine. Can. M i n . , v. 12, pp. 469-474.  Assemblages  R o b e r t s o n , J.M.,'1975. Geology and M i n e r a l o g y o f some Copper S u l p h i d e D e p o s i t s near Mount Bohemia, Keweenaw County, M i c h i g a n . Econ. G e o l . , v. 70, p p o 1202-1224. R o b i e , R.A., Hemingway, B.S., and F i s h e r , J . R . , 1978. P r o p e r t i e s o f M i n e r a l s and R e l a t e d S u b s t a n c e s . 1452, 456p.. Roseboom, E.H„, 1962. D j u r l e i t e , Cu pp. 1181-1184.  cS,  q  Thermodynamic U.S.G.S. B u l l e t i n  a New M i n e r a l .  Am. M i n . , v.  47,  Roseboom, E.H., 1966. An I n v e s t i g a t i o n o f the System Cu-S and some N a t u r a l Copper S u l f i d e s Between 25* and 700*C. Econ. G e o l . , v. 6 1 , pp. 641672. S c h o u t e n , C , 1962„ D e t e r m i n a t i o n T a b l e s f o r Ore M i c r o s c o p y . C o . , Amsterdam, 242p..  Elsevier  Pub.  S i l l i t o e , R.H., and C l a r k , A . H . , 1969. Copper and C o p p e r - I r o n S u l ; h i d e s as the I n i t i a l P r o d u c t s o f Supergene O x i d a t i o n , Capiapo M i n i n g D i s t r i c t , N o r t h e r n C h i l e . Am. M i n . , v. 54, pp. 1684-1710. S i n c l a i r , A . J . , 1976. A p p l i c a t i o n s o f P r o b a b i l i t y Graphs i n M i n e r a l E x p l o r a t i o n . A s s n . o f E x p l o r a t i o n Geochemists, Spec. V o l . No. 4, 95p.. S u t h e r l a n d - B r o w n , A . , C a t h r o , R . J . , P a n t e l e y e v , A . , and Ney, C.S., 1971. M e t a l l o g e n y o f the Canadian C o r d i l l e r a . CIMM B u l l e t i n , v. 64, No. 709, pp. 37-61. T a y l o r , L.A., and K u l l e r u d , G . , 1970. M i n e r a l Assemblages i n the C u - F e - S - 0 S y s t e m . . Carnegie I n s t . Wash. Yearbook 69, pp. 315 318. -  201  Thompson, A . B . , ' 1 9 7 1 . Ana 1 c i t e - A l b i t e E q u i l i b r i a at Low Am. J o u r . S c i . , v. 271, pp. 79~92.  Temperatures.  T i p p e r , H.W., 1959. R e v i s i o n o f the H a z e l t o n and T a k l a Groups o f B r i t i s h Columbia. G e o l . S u r v . Can., B u l l e t i n 47, 60p..  Central  T i p p e r , H.W., and R i c h a r d s , T . A . , ' 1 9 7 6 . J u r a s s i c S t r a t i g r a p h y and H i s t o r y of N o r t h - C e n t r a l B r i t i s h Columbia. G e o l . S u r v . C a n . , B u l l e t i n 270, 73p.. T u r e k i a n , K.K., 1972. C h e m i s t r y o f the E a r t h . I n c . , New Y o r k , 131 p..  Holt, Rinehart  and  U y t e n b o g a a r d t , W., 1968. Tables f o r Microscopic I d e n t i f i c a t i o n of Minerals. Hafner Pub. Co., New Y o r k , 2 4 2 p . .  Winston  Ore  W i l l i a m s , H. , T u r n e r , F . J . , and G i l b e r t , C M . , 1954. P e t r o g r a p h y , An I n t r o d u c t i o n to the Study o f Rocks in T h i n S e c t i o n s . W.H. Freeman and Co., San F r a n c i s c o , 406p.. W i l t o n , D.H., and S i n c l a i r , A . J . , 1978. O r i g i n o f the S u s t u t Copper Central B r i t i s h Columbia. CIMM B u l l . , v. 7], pp. 129.  Deposit,  W i l t o n , D.H., and S i n c l a i r , A . J . , 1 9 7 8 . G e n e t i c Model f o r the S u s t u t Copper Deposit i n T r i a s s i c V o l c a n i c l a s t i c Rocks, C e n t r a l B r i t i s h Columbia, paper s u b m i t t e d t o the 1978 IAG0D o r g a n i z a t i o n a l committee f o r i n c l u s i o n i n symposium volume. Yund, R.A., and K u l l e r u d , G., 1966. Thermal S t a b i l i t y o f Assemblages Cu-Fe-S System. J o u r . P e t . , v. 7, pp. 454-488.  i n the  202  APPENDIX I "GEOLOG"  DRILL CORE CODING FORMAT FOR SUSTUT COPPER  Introduction The v a s t q u a n t i t y o f d r i l l  c o r e r e q u i r e d t h a t any r e - l o g g i n g  standardized c o n s i s t e n t l y f o r a l l holes  r e c o r d e d and t h a t the data be p l a c e d  i n a computer based f i l e such t h a t q u i c k a c c e s s c o u l d be a c h i e v e d .  t o , and comparison o f d a t a  Thus, w i t h a computer f i l e a l l the v a r i a b l e s  recorded c o u l d  be m a n i p u l a t e d w i t h r e s p e c t to each o t h e r , such t h a t the s i g n i f i c a n t f o r copper o c c u r e n c e  be  and thus o r i g i n c o u l d be a s c e r t a i n e d .  chosen were those the a u t h o r thought would have been u s e f u l  The  variables  variables  based on  previous  logs o f the c o r e o b t a i n e d from F a l c o n b r i d g e N i c k e l Mines L t d . p r i o r to the s t a r t o f the f i e l d s e a s o n .  The format was f o r m u l a t e d p r i o r to the a u t h o r ' s  a t the f i e l d camp but on the whole the v a r i a b l e s t o r e c o r d each d r i l l  hole.  s e l e c t e d were more than  i t was  T h i s p a r t i c u l a r system was  r e l a t i v e l y s i m p l e to i n c o r p o r a t e i n t o f i e l d work, was  to a r i g i d e i g h t y column format (thus  l i m i t i n g complexity of e n t r i e s )  shown i t s v e r s a t i l i t y i n a p p l i c a t i o n to o t h e r d i f f e r e n t types o f The v a r i a b l e s  chosen  1) . rock type and, conglomerates  (and the reason  they were chosen)  restricted and had  deposits.  are:  in the case o f the dominant v o l c a n i c l a s t i c  (or b r e c c i a s ) , s u b d i v i s i o n  on the b a s i s o f c o l o u r o f the m a t r i c e s  v s . dominant c l a s t vs_. minor c l a s t , type o f c l a s t s and g r a i n s i z e o f c l a s t s .  adequate  The format used was a v a r i a t i o n on the " G e o l o g "  concept d e v e l o p e d by B l a n c h e t and Godwin ( 1 9 7 2 ) . chosen as  arrival  present,  texture,  sorting,  T h i s data would be used t o t r y to d e f i n e a  stratigraphy. 2) thought host  t y p e , grade and mode o f o c c u r e n c e o f a l t e r a t i o n m i n e r a l s .  It was  t h a t the d e p o s i t o r i g i n a t e d from metamorphic f l u i d s f l o w i n g through  rocks  (Harper;  metamorphic m i n e r a l  1977), thus assemblages.  the i n c l u s i o n o f d e t a i l e d i n f o r m a t i o n on the  the  203 t y p e , p e r c e n t p r e s e n t , and mode o f o c c u r e n c e o f the a c t u a l m e t a l l i c  3) mi n e r a l s . k)  type and number o f a l t e r a t i o n m i n e r a l v e i n s .  order that relationships  T h i s was  included  between s u l p h i d e m i n e r a l i z a t i o n and v e i n i n g ,  if  c o u l d be a s c e r t a i n e d '(eg. were l e n s o i d o r e b o d i e s f e d by hydrothermal type o f s t r u c t u r e p r e s e n t ,  5)  p e r p e n d i c u l a r p l a n e to the c o r e  i n t o f i v e groups o f f i v e .  The secondary  o t h e r d e s c r i p t i o n cards  rows  t h i s new l e v e l  is  It c o n s i s t s  of t w e n t y - f i v e  The f i r s t row f o r each  a f i v e f o o t i n t e r v a l from the  i f the f i v e f o o t  group,  previous  i n t e r v a l must be s u b d i v i d e d  i n s e r t e d between i n t e r v a l s ) .  if  The form a l s o has a v i s u a l  can be r e p r e s e n t e d as a manual  would be u s e d , f o r i n s t a n c e ,  i f the i n f o r m a t i o n was not keypunched  ( i e . the logs are used as the f i n a l  (eg.  bottom i n t e r v a l , then a c a r d  l o g column so t h a t v a r i a b l e s  computer use  rows  i n between are f o r comment cards o r f o r e n t r y o f  the rock type changes two f e e t from the p r e v i o u s for  veins?).  axis.  o u t l i n e d by t h i c k e r l i n e s , r e p r e s e n t s l e a d row.  present,  i f any, and i t s a n g l e from a  F i g u r e 86 shows the a c t u a l c o d i n g f o r m . which are subdivided  in  strip  log.  This  for  data s e t ) .  The Codes T i t l e card: of that d r i l l  Each d r i l l hole.  t h e h o l e number  a r e the degrees bearing  i s at the s t a r t o f a new h o l e . ( r i g h t j u s t i f i e d ) , k columns  i f the h o l e i s  i n c l i n e d (degrees  f o r the d i p ( t h e f i r s t two columns  and minutes)  With the c o m p l e t i o n o f the t i t l e  hole l i t h o l o g y begins.  line  Then, t h e r e a r e 3 columns  o f d i p , and the l a s t two are the m i n u t e s ) , k columns  UTM c o - o r d i n a t e s . drill  card with i d e n t i f y i n g c h a r a c t e r i s t i c s  The f i r s t column c o n t a i n s a T to i n d i c a t e t h a t t h i s  i n t h e computer f i l e for  h o l e has a t i t l e  and 18 columns  f o r the f o r the  c a r d , d e s c r i p t i o n of  the  Each l i n e r e p r e s e n t s a s i n g l e computer c a r d .  HOLE  V I S  u A  PAGE  NUMBER  ASSAY DATA  Assay  Int.  Cu Assay  S U S T U T C U 'GFOI .OG' D R I L L C O R E C O D I N G DEPTH BOTTOM  H Rx typtt is nnt Ang-:  TO  ROCK  OF  £ FRAGMENT  1  d.  12.  « | n h * l  ID.  ALTERATION EP  HAJ.  TYPE  INTEBVAL,  1-7-JB tnr r n l n u r s  i  6  3  22  £1  •Ha*.  CL  HE  QZ  CB  39  UP  FORMAT  MINERALIZATION  MINERALS  How  Fig Ham  ZE  PH  XL  PU  OTH  53  cu  PY  CP  BN  HS  OF  FRACTURES S T R U C T U R E S CC  OTHER  205 Column 1:  This  column i s used to i n d i c a t e t h a t the remainder o f the card  e i t h e r to be noted f o r some r e a s o n , or e x t r a comments on a p r e c e d i n g  is  interval  a r e t o be made. Codes:  C_-indicates a more d e t a i l e d d e s c r i p t i o n o f the i n t e r v a l It  above.  i s f o l l o w e d by w r i t t e n d e s c r i p t i o n ,  D_-indicates  t h a t a dyke i s p r e s e n t  E_-indicates  the card is an end c a r d  in the i n t e r v a l . (eg. f o r h o l e 110,  would be END OF HOLE 110 w i t h the E i n column F-indicates  a f a u l t is present  J_-indicates  the rock type o f the i n t e r v a l  bed (eg.a M-indicates  tuffaceous  format  1).  i n the i n t e r v a l . is a d i s t i n c t  inter-  layer)  the c o r e f o r the i n t e r v a l was m i s s i n g  and  l o g g i n g was e x t r a p o l a t e d from l o g s o f F a l c o n b r i d g e  thus Nickel  Mines L t d . . S-indicates  t h a t comments f o l l o w rock type d e c l a r a t i o n .  T _ - i n d i c a t e s the c a r d i s a t i t l e c a r d X-indicates  some o f the core  ^ - i n d i c a t e s the i n t e r v a l Columns  2 and 3:  is  (see  above).  missing,  is a v e i n .  These columns s t a t e the copper assay i n t e r v a l  in f e e t  (again  right j u s t i f i e d ) . Columns h to 6:  Copper assay v a l u e .  k and 5 (J_e_. 1.58  p e r c e n t = 158  Columns  Depth t o base o f  7 to 11:  is missing  a g a i n , but  l e f t blank  is a b s e n t , but would be between  in the f o r m a t ) . interval described  i t would be between 10 and 11.  g e n e r a l l y be i n f i v e f o o t s i g n i f i c a n t change  The decimal  i n t e r v a l s throughout  in ( f t ) .  point  These depths would  the h o l e except where t h e r e is a  i n rock c h a r a c t e r i s t i c s between i n t e r v a l s .  i f the depth was l e s s  Decimal  Column k would be  than 1000ft (J_e. the depth i s r i g h t j u s t i f i e d ) .  206  Column 12:  Type m o d i f i e r :  where comments d i r e c t l y  rock type was o t h e r than v o l c a n i c l a s t i c s t h i s column.  O t h e r w i s e t h i s column i s  Columns 13 t o 16: rock types  Rock t y p e :  t h i s dominant  if  (see b e l o w ) , a l e t t e r C i s p l a c e d  left  in  blank.  a f o u r l e t t e r code i s u s e d .  i n t e r s e c t e d are v o l c a n i c l a s t i c sediments,  used by g e o l o g i s t s  f o l l o w rock name, o r  >90 p e r c e n t o f  the  thus the code n o m e n c l a t u r e  o f F a l c o n b r i d g e N i c k e l Mines L t d . has been adapted to code  rock t y p e .  AG£R-indicates  agglomerate  (or v o l c a n i c l a s t i c c o n -  g l o m e r a t e ) w i t h a green m a t r i x ( f i r s t G_) , d o m i n a n t l y green c l a s t s and minor red c l a s t s .  Other examples  are:  ARGR-red m a t r i x , green > red c l a s t s , ARR6-red m a t r i x , red > green  clasts.  AGGG-green m a t r i x , green c l a s t s . There a r e a t o t a l  of eight possible  etc.  rock types w i t h i n t h i s code  Other l i t h o l o g i e s p r e s e n t and t h e i r codes  framework.  are:  AREN-arenaceous s a n d s t o n e ARGL-argi11i te CASN-casi ng FELS-fels ite MYLN-myloni t e SAND-sandstone TUFF-tuff WACK-wacke If columns  rock t y p e i s one o f t h e s e o t h e r t y p e s then the r e g u l a r f o r m a t s o f  17 to 28 do not a p p l y , the t y p e m o d i f i e r column i s f i l l e d and 17 to 28  a r e used to d e s c r i b e c o l o u r and/or t e x t u r e o f t h i s o t h e r rock t y p e . and t e x t u r e are not coded but a r e j u s t e n t e r e d as  descriptions.  The c o l o u r  207 Columns 17 t o 2 8 :  ( f o r vol c a n i c l a s t i c conglomerates).  Column 17:  Percent o f matrix i n i n t e r v a l .  Column 18:  P e r c e n t o f major c o l o u r e d fragment.  Column 1 9 :  P e r c e n t o f minor c o l o u r e d f r a g m e n t .  Code:  S c a l e o f 1 t o 10 where each u n i t = 10 p e r c e n t l_i_e_. 10%=1 50%=5) i f <10 p e r c e n t then T ( r a c e ) i s used.  Column 2 0 :  G r a i n s i z e o f c l a s t s vs_. m a t r i x . The i nequi g r a n u l a r g r a i n s i z e shown i n f i g u r e 45 i s used.  Column 21: T e x t u r e o f t h e vo1 c a n i c l a s t i c s . The i n e q u i g r a n u 1 a r c h a r t o f B l a n c h e t and Godwin (1972) TEXTURE  1.  CODES  texture  i s used ( f i g . 8 7 ) .  FOR  IGNEOUS <*)  lnequigramiJ»T (Forphyritic , C ongto.me r»tic> Struciur* or F r imf'Ctk  Open, dit rup'.ed  p e t c c D i t ^ c oi  1  OO  6  fe T" fiction  10-25 2i" be 1  2  3  1  s  9  4  Fig. 87 Column 22:  The s o r t i n g c h a r t  i n f i g u r e 88 i s used.  v. w e l l sorted • ASSIGNED  VALUE  mod. sorted  poorly sorted  v. poorly sorted  8  Fig. 88  Column 2 3 :  M a t r i x provenance- i f the f i n e f r a c t i o n t o c l a s t s r i c h , then F_ i s p l a c e d left  i n the column, o t h e r w i s e i t i s  blank.  Column 24: L i t h o l o g i c a l  i s feldspa  name o f dominant c l a s t .  208 Co 1 umn 25:  P e r c e n t o f t o t a l , c l a s t s = dominant  Column 26:  L i t h o l o g i c a l name o f minor c l a s t .  Col urhh 27:  Percent of t o t a l  Column 28:  L i t h o l o g i c a l name o f t r a c e c l a s t .  Codes:  c l a s t s = minor c l a s t .  P e r c e n t s a r e a 1 t o 10 s c a l e Lithological  clast.  ( e g . 101=1), <10%=T_(race) .  names a r e one l e t t e r  codes:  A-andes i t e B-basalt C-chert rj-d_i abase E_- f e l d s p a r  porphyry  F_-felsite _G-gjanitic H-trachyandesite j_-dacj_te L_-g2_ass IP-augite  porphyry  £-q_uartz R^-di o t i t i c _S_-£ediment T-tuff Y-rhyo1i t i c Columns 29 to 52:  A l t e r a t i o n minerals:  minerals are l i s t e d . carbonate  nine p o s s i b l y  d e f i n i t i v e metamorphic  These are e p i d o t e ( E P ) , c h l o r i t e (CH), h e m a t i t e (HE),  (CB) , q u a r t z (QZ) , z e o l i t e (ZE) , p r e h n i t e (PH) , and p u m p e l l y i t e (PL)) .  The f i r s t column f o r each m i n e r a l  (Amt) r e f e r s t o the amount o f m i n e r a l  T h i s code i s based upon a 1 to 5 s c a l e where; 1 means the m i n e r a l  present.  is j u s t  209  visible interval mineral.  i n the i n t e r v a l , w h i l e 5 means to the s t a g e  the m i n e r a l has e x t e n s i v e l y a l t e r e d the  t h a t the rock t y p e has almost c o m p l e t e l y gone to t h a t  The next two columns  (How) a l l o w f o r the d e s c r i p t i o n o f two modes  ( i f needed) o f o c c u r e n c e f o r each m i n e r a l . Codes f o r the modes a r e : A-amygdules E_-envelopes  outside  fractures  G - l o c a l i s e d to  fragments  K-s1ickensided  surfaces  L_-vug  j o i n i n g  M ^ - l o c a l i s e d to m a t r i x P_-patches,  b l e b s , metadomains, e t c .  _R-r_ims on c l a s t s S-s_elvages on edges o f U^pseudomorphs V-veins  veins  a f t e r m e t a l l i c mineral  (fracture f i l l i n g )  X-any c o m b i n a t i o n - t o be e x p l a i n e d i n the comments m i n e r a l was found  i n amygdules,  (eg. i f a  rims on c l a s t s and in v e i n s  an X^would be p l a c e d i n the How column and a comment c a r d would be i n i t i a l i z e d description.  immediately f o l l o w i n g the i n t e r v a l  On t h i s comment c a r d would be X=A,R_,V_ i n d i c a t i n g  the modes f o r X ) .  Columns  53 t o 55:  (OTH) - r e f e r to any metamorphic m i n e r a l p r e s e n t w h i c h i s  d e f i n e d i n the p r e v i o u s columns. drill  holes.  These m i n e r a l s a r e thus  less  common i n the  Column 55 i s f o r the mode o f o c c u r e n c e o f the m i n e r a l . Type codes CY-clay LI -1imon i t e  f o r these m i n e r a l s  are:  not  210  PL-pyrolus i te SP-serpent ine  C o l u m n s 56 t o 67: listed. (BN), part  Mi n e r a 1 i z a t i on w i t h e i g h t p o s s i b l e m e t a l 1 i c mi n e r a 1 s  These a r e n a t i v e  specular  hematite  is f o r the visual  copper  (CU) , p y r i t e  (HS) , a n d c h a l c o c i t e percent  The c o d e s j*-r_are  of mineral  (PY) , c h a l c o p y r i t e (CC).  The f i r s t  are  (CP), bornite  column  of  each  present.  f o r percent a r e :  trace  T-t_race  M-.05  - .1%  5.-.1 - .5%  2_-o5 -  n  2 - 1 - 2 %  E_->2%  The  last  column  (How) o f e a c h p a r t ,  t h e mi n e r a 1 . These codes  are:  A-amygdu1es C^-discrete  metal  cjast  D_-d i s s e m i n a t e d G_-localised  to  fragment  K-s1ickensided  surfaces  P_-pa i n t R-_rims on  clasts  S_-s_elvages o n \/-veins  veins  (fracture  >-veins>diss. =-veins=diss.  filling)  refers  t o t h e mode o f o c c u r e n c e  of  211 <-vei ns.<di s s .  Columns  68 to 71:  (OTHER)-refers  to the o t h e r p o s s i b l e m i n e r a l i z a t i o n types  which a r e not as abundant as the above o n e s .  Columns 68 t o 69 (ID) a r e f o r  the i d e n t i t y o f t h e m i n e r a l . The codes f o r l e s s xommon m i n e r a l s a r e : AZ-azur i te C I - c u p r i te CV-covel1i te GN-g_reenocki t e GR-graphi te MA-ma1ach i t e MT-magnet i t e SP-sphalerite Column 70 i s f o r t h e v i s u a l p e r c e n t and column 71 i s f o r t h e mode o f occurence o f the m i n e r a l .  Columns 72 t o 75:  These a r e f o r r e c o r d i n g t h e number o f c a r b o n a t e , e p i d o t e ,  q u a r t z , and c o m b i n a t i o n v e i n s carbonate veins)  r e s p e c t i v e l y ( i e . column 72 i s t h e number o f  w i t h i n the i n t e r v a l .  The number symbols j _ to 0_ r e f e r t o 1 t o  10 v e i n s , A_ - 1_ a r e f o r 11 to 36 v e i n s , and i f the number o f v e i n s a + i s e n t e r e d i n the p r o p e r column. veins  i s >36,  then  In a f o l l o w i n g comment c a r d the number o f  i s then d e f i n e d (eg. i f t h e r e a r e 54 e p i d o t e v e i n s , a + i s e n t e r e d i n  column 73, and i n a comment c a r d +=54 i s w r i t t e n ) . The c o m b i n a t i o n v e i n s  (column 75), a r e any v e i n s which a r e e i t h e r  c o m b i n a t i o n s o f t h e p r e c e d i n g t h r e e t y p e s , o r a r e made o f d i s t i n c t l y d i f f e r e n t v e i n m a t e r i a l s not mentioned above. the i n t e r v a l ,  If o n l y one type o f v e i n i s p r e s e n t i n  then the number i s p l a c e d i n t h e column and t h e m i n e r a l o g y  i s e x p l a i n e d i n a f o l l o w i n g comment c a r d .  However  i f t h e r e i s more than one  212  . other  type then a ^_ i s p l a c e d  are e x p l a i n e d  in a following  two c h l o r i t e v e i n s -=kPH + 2 C H i s  in the  in the column and the numbers comment c a r d  i n t e r v a l ^_ is  leg.  put  if  and types o f  veins  t h e r e are f o u r p r e h n i t e and  in column 75 and  in a comment  card  written). Codes  f o r d i f f e r e n t v e i n types  are:  CH-chlorite CQ-carbonate  > quartz  CE-carbonate  > epidote  EC-epidote > carbonate EQ-epi dote > q u a r t z HE-hematite PH-prehn i te QE-quartz > epidote QC-quartz > carbonate  Columns 76 of  to 80:  structures  angle of  (if  (STRUCTURES): any)  These columns  are p r e s e n t  in the  are f o r d e s c r i b i n g what  interval.  79 and 80 are f o r  t h e s t r u c t u r e to a p e r p e n d i c u l a r p l a n e to the c o r e a x i s Codes  for  the s t r u c t u r e s  are:  BED-beddi ng CNT-contact GBP-graded bedding S F R - s 1 i ckens i ded VEhhdominant  fractures  veining  direction  (in  types the  degrees).  213  APPENDIX I I  FOSSIL IDENTIFICATION T h i s appendix c o n t a i n s a copy o f G.S.C. Report 4-BEBC-78 w h i c h describes f o s s i l Sample 4 7 - 1 2 0 '  i d e n t i f i c a t i o n s f o r two samples  i s from the 1 2 0 f t l e v e l  o f DDH kj.  c o l l e c t e d by t h i s w r i t e r . Sample W1009 i s  an o u t c r o p w i t h UTM c o o r d i n a t e s o f 49,340N and 4 9 , l 8 0 E .  from  2.14  Report Ho.  4-BEBC-78  Report on microfauna recovered from 2 i n s o l u b l e residues c o l l e c t e d by Derek Wilton from NTS 94D, area,  McConnell Creek map  Sustut Copper, northern B.C. "The relevant parts of any manuscript prepared f o r pub-  l i c a t i o n that paraphrase or quote from t h i s paper should be r e f e r r e d t o the writer , G e o l o g i c a l Survey of Canada,  Vancouver,  for possible revision." G.S.C. L o c a l i t y : NTS 94D,  95344-  F i e l d No.  McConnell Creek map area;  Determinations:  Shell  47 - 12Q  Sustut Copper,  1  B.C.  fragments  Sponge s p i c u l e s F i s h tooth C r i n o i d columnal fragment AGE:  Indeterminate  G.S.C. L o c a l i t y : NTS 9 4 D ,  95345  F i e l d No.  McConnell Creek map area,  Determinations:  V/1009  Sustut Copper,  B.C.  C o r a l fragments Gastropods Foraminifera - Ammodiscus F i s h debris F i s h teeth  2  215  -2-  (determinations f o r V71009 continued)  Conodonts:  Epigondolella fragments - most  l i k e l y Bpigondolella p r i m i t i a Mosher Neogondolella sp. - blade f r a g ment only. AGE: Late T r i a s s i c ,  Late Karnian - early Norian.  r  217  APPENDIX I I I CROSS-SECTIONS This appendix provides cross-sections:  A - A ' , B - B , C - C , and D-D . 1  these c r o s s - s e c t i o n s Each l e v e l  a w r i t t e n d e s c r i p t i o n t o accompany 1  Ore m i n e r a l s a r e r e p r e s e n t e d on  i n h i s t o g r a m form w i t h symbols as e x p l a i n e d i n t h e l e g e n d s .  on t h e s e d r i l l h o l e - h i s t o g r a m s  for the various  the attached  is a f i v e foot  m i n e r a l s a r e based p u r e l y on v i s u a l  interval.  Percentages  estimations of content  w i t h i n the core. The c r o s s - s e c t i o n s  from the N o r t h Zone (j_e. A - A ' and B - B ' ) have t h e b e s t  d e f i n e d n a t i v e copper c o r e s , but they a l s o b o r n i t e , c h a l c o p y r i t e , and p y r i t e z o n e s . DDH 44 has a n a t i v e c o p p e r - c h a 1 c o c i t e  have poor development o f t h e o u t e r In s e c t i o n A - A ' (DDH's  53~52);  z o n e , then 10 m below t h i s , a s m a l l  p y r i t e - c h a l c o p y r i t e - b o r n i t e zone; DDH 53 has o n l y n a t i v e  copper-cha1cocite;  and i n DDH 52 a c h a l c o c i t e - n a t i v e copper c o r e has an upper b o r n i t e - c h a l c o p y r i t e p y r i t e f r i n g e but no f r i n g e on t h e b o t t o m .  In s e c t i o n B-B'  (54-110-17 52); _  DDH 54 has some c h a l c o c i t e and n a t i v e copper mixed w i t h i n a d o m i n a n t l y  pyrite  z o n e ; DDH 1 1 0 , . i n i t s upper o r e l e n s has two c h a l c o c i t e - n a t i v e copper c o r e s grade  to p y r i t e - c h a 1 c o c i t e f r i n g e s ,  although  been-removed by e r o s i o n ; and DDH 17 c o n t a i n s  t h e uppermost  that  e x p e c t e d f r i n g e has  a c h a l c o c i t e - n a t i v e copper  core  w i t h an u p p e r ' b o r n i t e - c h a l c o p y r i t e f r i n g e and a p y r i t e - c h a l c o p y r i t e zone 6 m b e l S m a l l e r zones a r e p r e s e n t p a r t i c u l a r l y well  is  developed.  S e c t i o n C-C  1  distinct  through t o t h e base o f DDH 110, but no zone  (88-2-IO5-67J.12}^contaj ns;;DDH ,88'.wi t h t h e above  z o n a t i o n and a l s o s m a l l e r s u l p h i d e  zonation.throughout;  lenses,  DDH 2 w h i c h has an e x t e n s i v e  some w i t h w e l l  mentioned  developed  p y r i t e zone w i t h two s m a l l  cha 1 c o c i t e - b o r n i t e zones sandwiched w i t h i n t h e p y r i t e ; i n DDH 105 a s m a l l cha 1 c o c i t e - b o r n i t e zone  i s i n t h e c e n t r e o f an asymmetric p y r i t e - c h a l c o p y r i t e  218 zone w i t h a s m a l l  isolated cha1cocite-bornite  large cha1cocite-native  copper 2one w i t h a s m a l l  and DDH 112 has a n a t i v e c o p p e r - c h a 1 c o c i t e  (132-13-116-10-39-96);  b o r n i t e zones i r r e g u l a r l y  sandwiched  p y r i t e - c h a 1 c o p y r i t e lower  c o r e zone w i t h a lower  p y r i t e f r i n g e but no upper p y r i t e - c h a l c o p y r i t e In s e c t i o n D-D'  zone a t t h e t o p ; DDH 6 c o n t a i n s a fringe;  pyrite-chalco-  fringe. DDH 96 has two c h a l c o c i te.-  between p y r i t e - c h a l c o p y r i t e a s s e m b l a g e s ;  DDH 35 has a broad c h a l coc i t e - n a t i ve copper zone w i t h a smal'l born i t e - c h a l c o pyrite  l o w e r f r i n g e ; DDH 10 c o n s i s t s  DDH 116 a l s o containing  of three seperated c h a 1 c o c i t e - r i c h  has t h r e e s e p a r a t e c h a l c o c i t e i n t e r s e c t i o n s ,  some n a t i v e c o p p e r ;  lenses;  the uppermost one  DDH 13 has t h r e e w i d e l y s e p a r a t e d  chalcocite  zones w i t h a broad minor p y r i t e - c h a 1 c o p y r i t e a r e a between t h e lower t w o , and finally has  DDH 132 c o n t a i n s  three p y r i t e zones,  no a p p r e c i a b l e c o n c e n t r a t i o n Of copper m i n e r a l s but one o f w h i c h c o n t a i n s  chalcopyrite  in its. centre.  

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