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Geology and genesis of the Dolly Varden silver camp, Alice Arm area, northwestern British Columbia Devlin, Barry David 1987

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GEOLOGY AND GENESIS  OF THE DOLLY VARDEN  SILVER CAMP  A L I C E ARM AREA, NORTHWESTERN BRITISH COLUMBIA By BARRY DAVID DEVLIN B.Sc,  The U n i v e r s i t y o f B r i t i s h  C o l u m b i a , 1981  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF  SCIENCE  in THE FACULTY  OF GRADUATE  (Department o f G e o l o g i c a l  accept  this  t h e s i s as conforming  THE UNIVERSITY  STUDIES Sciences)  to the required  OF BRITISH COLUMBIA  March 1987 (c) B a r r y  David  Devlin,  1987  standard  In  presenting  degree  at  this  the  thesis  in  University of  partial  fulfilment  of  of  department publication  this or of  thesis for by  his  or  that the  her  representatives.  It  this thesis for financial gain shall not  Department The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3  for  an advanced  Library shall make  it  agree that permission for extensive  scholarly purposes may be  permission.  DE-6(3/81)  requirements  British Columbia, I agree  freely available for reference and study. I further copying  the  is  granted  by the  understood  that  be allowed without  head  of  copying  my or  my written  Page  F r o n t i s p i e c e . V i e w l o o k i n g n o r t h up t h e w i t h t h e T o r b r i t mine i n t h e f o r e g r o u n d i n the background.  i i  Kitsault River valley, and t h e K i t s a u l t G l a c i e r  Page i i i  ABSTRACT  The  Dolly  Columbia,  V a r d e n camp, A l i c e  i s c h a r a c t e r i z e d by s t r a t i f o r m  silver-lead-zinc-barite calc-alkaline deposits, metal  as l a y e r s  lesser  that  and T o r b r i t  averaged  percent  The basaltic  Production  mines,  484g s i l v e r  Hazelton  Group  to r h y o l i t i c  sphalerite  base  barite  and j a s p e r ,  and g a l e n a ,  and s p a r s e  three d e p o s i t s , the D o l l y  totaled  per tonne,  i s a thick,  Varden,  1,284,902 t o n n e s o f o r e 0.38 p e r c e n t  widespread  lead  and 0.02  into  stratigraphic  relative  r o c k s and h a v e units  consist  comprised  formation. been  based  to the m i n e r a l i z e d  Footwall v o l c a n i c rocks  V a r d e n camp i s  Group r o c k s  sedimentary  f o o t w a l l and h a n g i n g w a l l  position  tuffaceous  rocks. Dolly  3,000m o f H a z e l t o n  rocks u n d e r l i e sedimentary  subdivided  assemblage o f  v o l c a n i c flow rocks, t h e i r  one m a j o r v o l c a n i c and one m a j o r  horizon.  These  t u f f a c e o u s r o c k s , and o c c u r  and d e r i v e d s e d i m e n t a r y  u n d e r l a i n by more t h a n  Volcanic  Group.  zinc.  equivalents,  of  from  Jurassic  and s i g n i f i c a n t  of quartz, carbonate,  amounts o f p y r i t e ,  chalcopyrite. Northstar  t o Middle  v o l c a n i c rocks of the Hazelton  values, are i n andesitic  British  and v o l c a n o g e n i c  deposits i n Early  containing exceptional silver  typically with  Arm a r e a , n o r t h w e s t e r n  on  stratiform  o f g r e e n _+ maroon  Page i v  basaltic-andesite green  tuff,  andesite shard  green  tuff.  + maroon p o r p h y r i t i c  Stratiform  conformably  upon t h e u n d e r l y i n g g r e e n  Hangingwall  v o l c a n i c rocks  pale grey  basaltic-andesite  ash-lapilli green  tuff,  unconformably siltstone,  and  rock  of  unit and  Group.  c a p p e d by  folded  into  northwest  and  younger  Geological isotopic  probably  data,  of  wacke, and  and  s h a l e form  a series  of  major  of  maroon  youngest  area.  the  Hazelton  i n the  of a n t i c l i n e s Two  and  Dolly synclines  s e t s of n e a r l y  units;  faults  north-northeast.  t h a t the  pale  the  Varden  group exposed  trend  of  black  cut a l l rock  indicate  earlier  petrologic, stratiform  faults  trend  petrographic  deposits  submarine e x h a l a t i v e d e p o s i t s a s s o c i a t e d w i t h  volcanism  Jurassic.  conformity  rocks c o n s i s t i n g  plunges.  consist  v o l c a n i c s are  mapping, combined w i t h  f o r m e d as  andesitic Middle  faults  layer  basaltic-andesite  intrude a l l rocks  Hazelton  tuff.  a n d e s i t e , and  Group i n the D o l l y  gentle, northwestern block  maroon  fossiliferous  the Hazelton  vertical  and  sedimentary  r o c k s of the  andesite shard  porphyritic  Hangingwall  lamprophyre dykes  The  tuff,  and  mineralization rests  stratiform  shale; black s i l t s t o n e  V a r d e n camp a r e with  tuff.  c a l c a r e o u s and  siltstone  ash  grey-green  a n d e s i t e ash  Basalt  above the  andesite  of the H a z e l t o n  Evidence  Group d u r i n g t h e E a r l y  for a volcanogenic  layered m i n e r a l i z a t i o n with  origin  to  i s the  stratigraphy, lateral  Page v  and  vertical  versus ore  mineral  footwall  within  consistent  zonation  contact  tuffaceous  consistent  rocks of the hangingwall,  i n the s t a b l e  between t h e s u l f i d e s v e r s u s  isotopic  b a r i t e , quartz  compositions  and c a r b o n a t e  and  the J u r a s s i c  " f i n g e r p r i n t " f o r the lead-bearing  the  Dolly  camp.  The  Varden  Dolly  classification volcanogenic, and  Varden deposits  i s characterized  stratiform  display  o f a new, p r e v i o u s l y deposit  hangingwall  r e l a t i o n s h i p s , fragments of s t r a t i f o r m  volcanic  differences  patterns,  type,  mineralization  within  deposits  of  criteria for  unrecognized,  named h e r e ,  by s i l v e r - r i c h ,  gangue,  s t r a t i f o r m and  the " D o l l y  low s u l f i d e  Varden  and h i g h  andesitic volcanic  rocks.  type", oxide  Page v i  TABLE OF  CONTENTS  page  FRONTISPIECE  i i  ABSTRACT  i i i  TABLE OF CONTENTS  vi  L I S T OF TABLES  viii  L I S T OF FIGURES  ix  ACKNOWLEDGEMENT  xv  1 .0  INTRODUCTION  1  2.0  REGIONAL GEOLOGY  5  2.1  INTRODUCTION  5  2.2  HAZELTON VOLCANIC-SEDIMENTARY  2.3  TERTIARY INTRUSIVE UNITS  2.4  STRUCTURE  1 2  2.5  ALTERATION  12  3.0  UNITS  ( 1 TO 6)  (7 TO 9)  6 11  PROPERTY GEOLOGY  14  3.1  INTRODUCTION  14  3.2  LITHOLOGY  21  3.2.1  Footwall Volcanic  3.2.2  Stratiform Exhalative  3.2.3  Rocks  21  Silver-Lead-Zinc-Barite Mineralization  Hangingwall Volcanic  Rocks  26 38  Page v i i  page  4.0  5.0  3.2.4  S e d i m e n t a r y Rocks  57  3.2.5  Intrusive  62  3.3  CHEMISTRY  OF IGNEOUS ROCKS  3.4  STRUCTURE  72  3.5  ALTERATION AND VEIN MINERALIZATION  76  66  ISOTOPE STUDIES  84  4.1  INTRODUCTION  84  4.2  SULFUR, OXYGEN AND  CARBON ISOTOPES  Sulfur  Isotopes  85  4.2.2  Oxygen I s o t o p e s  90  4.2.3  Carbon  94  4.2.4  Discussion  94  4.2.5  Summary  97  Isotopes  4.3  POTASSIUM-ARGON ISOTOPES  4.4  LEAD ISOTOPES  5.1  INTRODUCTION  5.2  PHYSICAL AND  97 100  GENESIS OF THE STRATIFORM  5.3  84  4.2.1  MINERALIZATION  105 105  CHEMICAL  OF THE STRATIFORM  6.0  Rocks  CHARACTERISTICS  MINERALIZATION  GENETIC MODEL  105 113  CONCLUSIONS  119  BIBLIOGRAPHY  123  APPENDIX  131  J  STABLE ISOTOPE FRACTIONATION  EQUATIONS  131  Page  LIST  viii  O F TABLES page  TABLE 1.1  P r e v i o u s p r o d u c t i o n and r e s e r v e s f o r t h e D o l l y Varden  TABLE 2.1  camp, n o r t h w e s t e r n  Formations  i n the K i t s a u l t  northwestern TABLE 3.1  Petrography  Mineralogy (unit  4.1  Sulfur,  from 4.2  4.3  TABLE 4.4  (XRF) and f o r igneous  Varden  B.C.  isotope compositions of  temperatures  and o x y g e n compounds from  i n deposits B.C.  86  f o r pairs of  the D o l l y  Varden  B.C.  Varden  89 data  for volcanic  camp, n o r t h w e s t e r n  G a l e n a - l e a d i s o t o p e a n a l y s e s from camp, n o r t h w e s t e r n  67  camp, n o r t h w e s t e r n  depositional  the D o l l y  r o c k s from t h e  q u a r t z and c a l c i t e  Whole-rock potassium-argon from  horizon  camp,  camp, n o r t h w e s t e r n  barite,  16  28  calculations  camp, n o r t h w e s t e r n TABLE  B.C.  B.C.  the D o l l y  sulfur  sedimentary  camp, n o r t h w e s t e r n  Varden  o x y g e n and c a r b o n  Calculated  and  of the m i n e r a l i z e d s t r a t i f o r m  Varden  sulfides,  TABLE  Varden  Whole r o c k c h e m i s t r y  Dolly TABLE  7  3) i n t h e D o l l y  normative  River area,  of the v o l c a n i c  northwestern TABLE 3.3  4  B.C.  rocks of the D o l l y TABLE 3.2  B.C.  B.C.  rocks  B.C.  the D o l l y  98  Varden 101  Page  ix  Page x  page Figure  3.9  Steeply-dipping pyrite, from  Figure  3.10  layers  in silica-sulfide  the Dolly  Polished  slab  Anhedral crudely  Figure  3.12  Layers in  deposit.  31  t y p i c a l of the exhalite  pyrite  32  (unit 3a).  f o r m i n g m a s s i v e a g g r e g a t e s and  developed  exhalite  ( u n i t 3a)  o f q u a r t z and p y r i t e  silica-sulfide 3.11  exhalite  Varden East  mineralization,  Figure  of s u l f i d e s , mostly  layers  in silica-sulfide  (unit 3a).  of c a l c i t e ,  32 quartz,  b a r i t e and s u l f i d e s  carbonate-sulfate-sulfide  exhalite  (unit  3b)  from underground w o r k i n g s a t t h e Northstar Figure  3.13  deposit.  V e r t i c a l zonation Northstar  Figure  Figure  3.14  3.15  Polished  in drill  deposit,  northwestern  33  Dolly  camp, 36  slab  of c a l c i t e ,  barite  and s p h a l e r i t e  mineralization,  t y p i c a l of the carbonate-  sulfate-sulfide  exhalite  Massive s p h a l e r i t e  Colloform  bladed barite  layers  with crystals in  exhalite  of hematite  sulfate-oxide-sulfide  37  (unit 3b).  and p y r i t e  carbonate-sulfate-sulfide 3.16  Varden  B.C.  coarse-grained  Figure  h o l e U-80-95 i n  (unit 3b).  41  and m a g n e t i t e i n  exhalite  (unit 3c).  41  Page x i  page F i g u r e 3.17  Well developed l a y e r s of b a r i t e , j a s p e r and sulfides  in sulfate-oxide-sulfide exhalite  ( u n i t 3c) from underground workings a t the T o r b r i t mine. F i g u r e 3.18  42  P o l i s h e d s l a b of galena  and j a s p e r  m i n e r a l i z a t i o n , t y p i c a l of. massive s u l f i d e ore from the s u l f a t e - o x i d e - s u l f i d e e x h a l i t e (unit 3c). F i g u r e 3.19  43  Carbonate boulder,  30cm a c r o s s , i n p a l e  b a s a l t i c - a n d e s i t e ash t u f f  grey  ( u n i t 4) from  underground workings a t the N o r t h s t a r d e p o s i t . F i g u r e 3.20  Secondary f o l i a t i o n ash t u f f  F i g u r e 3.21  44  i n p a l e grey b a s a l t i c - a n d e s i t e  (unit 4).  44  Subrounded t o subangular maroon t u f f  lithic  fragments, up to 50cm a c r o s s , i n maroonbasaltic-andesite a s h - l a p i l l i F i g u r e 3.22  tuff  (unit 5).  48  P l a t y shards i n a l o c a l p y r o c l a s t i c flow w i t h i n maroon b a s a l t i c - a n d e s i t e ash-lapilli  F i g u r e 3.23  tuff  (unit 5).  L i g h t green, angular sized l i t h i c  49  t o subangular,  lapilli-  fragments, up t o 5cm a c r o s s , i n  dark grey a n d e s i t e  lapilli  tuff  (unit 6a).  54  Page x i i  page Figure  3.24  Hand  specimen of dark green a n d e s i t e  (unit from  6b) t h a t c o n t a i n s the  3.25  Thin  6b) t h a t  3.26  contains  b a r i t e o r e from  exhalite Figure  exhalite (unit  s e c t i o n of dark green andesite  (unit and  an o r e f r a g m e n t  underlying  sulfate-oxide-sulfide Figure  (unit  3.27  3.28  3.29  of quartz  the s u l f a t e - o x i d e - s u l f i d e 55  3.30  Well  bedding  3.31  wacke  Coarse-grained,  poorly  subrounded i n pale  7b).  56  i n calcareous  and  8b).  sorted  56  59  fragments i n 8b).  64  i n a p l a g i o c l a s e dominated groundmass.  64  B a s a l t dyke g r e e n +/(unit  (unit  (unit  7a).  fragments,  and f o s s i l i f e r o u s  B a s a l t dyke augite  Figure  and l i t h i c  ash t u f f  developed  (unit  f r a g m e n t s , and  green andesite  calcareous Figure  tuff  3c).  Plagioclase crystal  fossiliferous Figure  55  P h e n o c r y s t s o f p l a g i o c l a s e and h o r n b l e n d e i n  grains  Figure  3c).  fragments of carbonate  grey-green p o r p h y r i t i c andesite Figure  tuff  (unit  (unit  maroon  9) composed  wacke  (unit  of l a t h s of  9) c r o s s c u t t i n g basaltic-andesite tuff  1) on a r o a d c u t  near  the T o r b r i t  mine.  65  Page  xiii  page Figure  3.32  AFM d i a g r a m  f o r igneous rocks  i n the Dolly  V a r d e n camp, n o r t h w e s t e r n B.C. Figure  3.33  Total alkali Dolly  Figure  3.34  silica  68  (TAS) d i a g r a m  f o r the  V a r d e n camp, n o r t h w e s t e r n B.C.  Si02 vs Zr/Ti02  diagram  f o r the Dolly  69 Varden  camp, n o r t h w e s t e r n B.C. Figure  3.35  Well  developed a-c j o i n t s ,  northeasterly  direction,  to the northwesterly Figure  3.36  The v e r y Gold  3.37  Figure  4.1  4.2  4.3  Bear  75  Varden  Creek 82  veins  of the Dolly  Varden 83  plot  f o r deposits  from t h e  V a r d e n camp, n o r t h w e s t e r n B.C.  Range o f c a l c u l a t e d dfl 80 v a l u e s  the  axis.  3.1 a n d 3 . 4 ) .  Sulfur isotope  (Table  Figure  fold  Belt.  Dolly Figure  and p e r p e n d i c u l a r  prominent gossan of the D o l l y  Gold-silver-copper Gold  oriented i n a  trending  B e l t , near B l a c k  (Figs. Figure  70  4.1.) r e s p o n s i b l e  87  f o r ore f l u i d s  formineralization i n  D o l l y V a r d e n camp, n o r t h w e s t e r n B.C.  93  P l o t s o f 208Pb/204Pb v s . 206Pb/204Pb, 207Pb/204Pb v s . 206Pb/204Pb a n d 206Pb/208Pb vs.  206Pb/ 207Pb f o r d e p o s i t s  Figure  3.1 a n d l i s t e d  i n Table  l o c a t e d on 4.4.  104  Page x i v  page Figure  5.1  Idealized  cross-section  camp, n o r t h w e s t e r n Figure  5.2  Schematic stratiform  northwestern Figure  5.3  Varden  B.C.  reconstruction horizon  of the D o l l y  107 of the mineralized  i n the Dolly  Varden  camp,  B.C.  110  Model f o r g e n e s i s o f s t r a t i f o r m mineralization northwestern  i n the D o l l y  B.C.  Varden  camp, 114  Page xv  ACKNOWLEDGEMENT I w o u l d l i k e t o t h a n k C . I . Godwin f o r h i s g u i d a n c e a n d supervision of this project. Thanks a l s o a r e extended t o A . J . S i n c l a i r , J.K. R u s s e l l and D . J . A l l d r i c k f o r t h e i r h e l p d u r i n g r e s e a r c h a n d s u g g e s t i o n s f o r improvement o f t h e f i n a l manuscript. F i e l d s u p p o r t from P e t e r T h i e r s c h and V i c t o r K o y a n a g i , t e c h n i c a l and a n a l y t i c a l a s s i s t a n c e f r o m b o t h t h e D e p a r t m e n t o f G e o l o g i c a l S c i e n c e s and t h e D e p a r t m e n t o f O c e a n o g r a p h y a t The U n i v e r s i t y o f B r i t i s h C o l u m b i a , a n d s t a b l e i s o t o p e a n a l y s e s by H.R. K r o u s e f r o m t h e U n i v e r s i t y o f C a l g a r y , and K. M u e h l e n b a c h s f r o m t h e U n i v e r s i t y o f A l b e r t a , a r e g r a t e f u l l y acknowledged. S p e c i a l a p p r e c i a t i o n goes t o Karen D e v l i n f o r h e r e x c e l l e n t d r a f t i n g s k i l l s and m o r a l s u p p o r t . I w o u l d a l s o l i k e t o t h a n k W.F. C h r i s t e n s e n o f D o l l y V a r d e n M i n e r a l s I n c o r p o r a t e d , W.N. P e a r s o n o f D e r r y , M i c h e n e r , B o o t h and Wahl, C o n s u l t i n g G e o l o g i s t s a n d E n g i n e e r s , a n d t h e S c i e n c e C o u n c i l o f B r i t i s h C o l u m b i a f o r t h e o p p o r t u n i t y t o make t h e s e studies.  1 .0 INTRODUCTION  The  Dolly  Varden  silver  n o r t h and 129o 50' west River  27km u p s t r e a m  approximately (Fig. are  2.1).  steep.  Rupert, Alice  Topography Elevation  from by  The  Stewart,  be u s e d  Kitsault  River  Columbia  and v a l l e y  from  slopes  275 t o 1,050m  deposits  and p r o s p e c t s i s by  41km t o t h e n o r t h , o r P r i n c e  A gravel  This  r o a d from  village,  the v i l l a g e of  however,  i s isolated  on t h e o t h e r s i d e o f A l i c e  trip.  Kitsault  area i s part  region.  Arm  inlet  i s c o n n e c t e d by a  Mean d a i l y  primarily  of the Coastal  Mean a n n u a l p r e c i p i t a t i o n temperature  -15oC, and i n J u l y ,  i t i s less  i n January  Mountain  ranges  western  t h a n 14oC.  River  hemlock a t lower e l e v a t i o n s  and d e v e l o p m e n t valley  since  1  250  Vegetation i s  (Farley,  has been c a r r i e d  the f i r s t  from  r a n g e s between -10  s u b a l p i n e Engelmann s p r u c e and s u b a l p i n e f i r ,  Exploration Kitsault  British  r o a d t o t h e S t e w a r t - C a s s i a r highway.  350cm.  coastal  Arm,  f o r a c c e s s t o t h e camp p r o v i d e d m i n o r  out.  or f e r r y  55o 77'  the K i t s a u l t  Present access to the region  from  were c a r r i e d  physiographic  and  of Vancouver,  i n t h e camp r a n g e s  latitude  of A l i c e  i n the area i s rugged  t h e town o f K i t s a u l t  private  to  the small v i l l a g e  163km t o t h e s o u t h .  a 3km b a r g e  straddles  w i t h most o f t h e s i l v e r  either  Arm c o u l d  repairs  from  b e l o w 750m.  helicopter  (NTS: 103P),  850km n o r t h w e s t  above sea l e v e l , occurring  camp, c e n t e r e d n e a r  with  1979).  out i n the  c l a i m s were s t a k e d i n t h e  early is  1900's.  i n the  1985).  Much o f  recent  Most o f  the  book " S t e e l R a i l s the  at  the  1959  l e a d and  0.02  Torbrit  copper r e c o v e r e d  mine  intermittently  out  estimated (Table  1.1,  are  percent  Detailed  t o be  i n the  1919  0.29  was  3.1  to  reconstructed  3.3)  3836g  studies that  d e s c r i p t i o n s of ore  has  o x y g e n , c a r b o n and  galena-lead  work shows t h a t t h e  and  and  as been camp. for  the  326g s i l v e r  the  here  main 3km  per  include:  (1)  and  rocks,  host  for  ore  was  petrological  and  (2)  d a t i n g , and  isotope analyses.  the  mineral long  T h i s mapping  K-Ar  and  zinc.  allows  to s t r a t i g r a p h y .  1921  diamond  possible reserves  to a continuous  w h o l e - r o c k g e o c h e m i c a l a n a l y s i s and  (3)  sulfur,  Synthesis  of  D o l l y V a r d e n camp i s c h a r a c t e r i z e d by  silver-lead-zinc-barite  intermediate  surveys,  percent  to  Total gold  D o l l y Varden mining and  0.38  b e t w e e n 1949  1,354,596 t o n n e s a v e r a g i n g  (Figs.  detailed  petrographical  stratiform  from  F i g . 2.1).  geophysical  l e a d and  t h a t conforms  augmented by  this  (Muralt,  tonne,  (1:5,000) g e o l o g i c a l mapping p r e s e n t e d  V a r d e n camp  occurrences  and  camp  totaling  per  mining operations  proven, probable  1.1),  t o n n e , 0.24  horizon  Dreams"  took p l a c e  m i n e s , and  the  t r e n c h i n g , u n d e r g r o u n d d e v e l o p m e n t , as w e l l  carried  Dolly  of  E x p l o r a t i o n work c o n s i s t i n g o f  geochemical  camp  zinc,  (Table  geological,  Total  Silver  484g s i l v e r  Northstar  from these  191kg, r e s p e c t i v e l y . drilling,  averaging  percent  D o l l y V a r d e n and  at the  and  history  s i l v e r - b a s e metal p r o d u c t i o n ,  1,284,902 t o n n e s of o r e percent  early, colorful  v o l c a n i c rocks  deposits  intercalated  of E a r l y t o Middle  2  in  J u r a s s i c age.  In  addition  to s t r a t i f o r m  gold-silver-copper interpretations workers to  be  i n the  veins occur  represent area  epithermal Skerl,  1962;  focus  of  their  relationship  study  throughout  they  i s on to the  silver-lead-zinc  the  considered  (Hanson, 1921;  Carter,  both  camp.  a r a d i c a l departure  because  veins  1959;  this  mineralization,  1970; the  and  nature  stratiform  mineralization.  3  Black,  from  the  These previous  a l l mineralization 1951;  Mitchell, of  and  Campbell,  1973).  volcanic  The rocks  main and  silver-lead-zinc-barite  TABLE 1.1. Previous production and reserves for the Dolly Warden camp, northwestern Previous production!  *"  Deposit name  tonnes (tons)  Torbrit Dolly Varden  1,251,366 (1,379,372) 33,434 (36,854)  Northstar Wolf TOTAL 1. 2.  102 (112 ) 1,284,902 (1,416,338 )  Reserves2 (proven, probable and possible)  Ag  Pb  Zn  grams (ounces)  percent  percent  463 (13.52 ) 1,268 (37.03)  B.C.  0.40 0.003  0.02  Ag  Pb  tonnes (tons)  grams (ounces)  percent  percent  786,372 (866,812) 43,040 (47,443)  312 (9.10) 548 (16.00)  0.42  0.50  0.24  0.29  868 ( 25.34)  128,439 (141,577 )  484 (14.13 )  396,745 (437,329) 1,354,596 (1,493,161)  0.38  0.02  Zn  401 (11.71) 306 (8.92) 326 (9.51)  Previous production data i s from the Mineral Policy Sector, Department of Energy, Wines and Resources, Ottawa. Reserve estimates for the Torbrit and Dolly Warden deposits are from the Dolly Varden Wines Limited annual reports f o r 1971 and 1973, and estimates for the Northstar and Wolf deposits are from Thompson and Pearson, 1981.  2.0 REGIONAL GEOLOGY  2.1  INTRODUCTION  The the  Dolly  Varden mining  Intermontane B e l t ,  camp l i e s  a t the western  w i t h i n the S t i k i n i a  terrane  ( F i g . 2.1;  Coney e t a l . , 1 9 8 0 ) .  The r o c k s have b e e n c o r r e l a t e d  Hazelton  i s a thick  Group, which  assemblage of b a s a l t i c tuffaceous in  and R i c h a r d s ,  crustal  1976).  1984).  rocks,  t o Middle  The H a z e l t o n  basin, adjacent  extension related  Sigurdsson, seafloor  v o l c a n i c flow rocks,  Trough d u r i n g the E a r l y  represents a marginal by  to r h y o l i t i c  with the  island arc  e q u i v a l e n t s and d e r i v e d s e d i m e n t a r y  the Hazelton  (Tipper  and w i d e s p r e a d  margin of  Extension generated  Trough  probably  spreading fracture  deposited  Jurassic  to the i s l a n d  to back-arc  their  arc,  formed  ( C a r e y and  z o n e s and  g r a b e n s t h a t a c t e d a s t r a p s and l a r g e s c a l e b a r r i e r s t o  the d i s p e r s a l  and d e p o s i t i o n o f t h e v o l c a n i c and  r o c k s and a s s o c i a t e d s t r a t i f o r m deposits. produced erosion  o f t h e a r c complex.  shallow  subaqueous and/or  Sigurdsson,  i n this  e r u p t i o n s and by  Explosive volcanism  subaerial  eruptions  mineral b a s i n was  secondary i s t y p i c a l of  ( C a r e y and  1984).  Regional geology described  silver-lead-zinc-barite  Most o f t h e v o l c a n i c d e b r i s t r a p p e d by e x p l o s i v e a n d e s i t i c  sedimentary  of the K i t s a u l t  by M c C o n n e l l  (1913),  R i v e r a r e a was p r e v i o u s l y  T u r n b u l l (1916),  1922a, 1922b, 1923 and 1928) and B l a c k  5  (1951).  Hanson Geology  (1921, of the  Unuk R i v e r , Salmon R i v e r Grove  (1982,  Hanson upper  (1921) s u b d i v i d e d r o c k s o f t h e H a z e l t o n River valley  formation,  sedimentary area  and  Alldrick,  whereas B l a c k  by A l l d r i c k  and Dawson  shows t h a t t h e K i t s a u l t  G r o u p , and t h r e e T e r t i a r y (Table  2.1, F i g s .  2.2 HAZELTON VOLCANIC-SEDIMENTARY  Unit  1 , the lowermost  interbedded, with is  not exposed  remapping of  e t a l . , 1986; Dawson here  (cf_. D e v l i n and  River valley i s  units  intrusive  (1 t o 6) o f t h e units  (7 t o 9)  2.1 and 2 . 2 ) .  UNITS  (1 TO 6)  laminated  black  i n the K i t s a u l t  siltstone,  Although  and  argillite  the base o f t h i s  River valley,  unit  unit  1 i s at least  thick.  Unit  2, o v e r l y i n g u n i t  epiclastic  basalt  two  sequence exposed, c o n s i s t s of  m i n o r wacke and l i m e s t o n e .  1,200m  and  finely  i n the  and one  Recent  (Alldrick  by s i x v o l c a n i c - s e d i m e n t a r y  d e s c r i b e d below  Group  (1951) r e c o g n i z e d  1 9 8 6 ) , augmented by d e t a i l s  Godwin, 1 9 8 6 a , b ) ,  Hazelton  i n t o one s e d i m e n t a r y  and two v o l c a n i c f o r m a t i o n s .  the  underlain  by  1986).  Kitsault  volcanic  and Anyox map-area was c o m p i l e d  flows,  characteristic  rocks.  1, c o n s i s t s o f m i x e d m a f i c  Augite,  pyroclastics of the u n i t .  f e l d s p a r , and o l i v i n e  volcanic porphyritic  and d e r i v e d c o n g l o m e r a t e s a r e Thickness  t o 700m.  6  of unit  2 ranges from  150  TABLE 2.1. Formations in the Kitsault River area, northwestern B.C.  Era  Cenozoic  mesozoic  Period  Tertiary  Jurassic  Epoch  Group  Rock Unitl  Lithology  Eocene and Younger (22 ma; K-Ar)  Dykes (9)  basalt, lamprophyre, d i o r i t e , microdiorite  Early to Middle Eocene (43-55 Wa; K-Ar)  Alice Arm (Ajax) intrusions (8)  quartz monzonite, biotite quartz monzonite porphyry, s e r i c i t e quartz monzonite porphyry  Coast Range Batholith (7)  quartz monzonite, granodiorite  Upper sedimentary unit (6)  basal f o s s i l i f e r o u s uiacke, s i l t s t o n e , shale, sandstone, intraformational conglomerate,limestone  Epiclastic and f e l s i c volcanic unit (5)  maroon and green volcanic conglomerate, breccia, sandstone, black s i l t s t o n e , a r g i l l i t e , uiacke, limestone, greenish grey dacitic pyroclastic rocks, feldspar porphyritic flows  Intermediate volcanic unit (4)  green and minor maroon andesite pyroclastic rocks, feldspar + hornblende andesite porphyry black s i l t s t o n e , maroon siltstone sandstone, conglomerate, limestone, f o s s i l i f e r o u s limestone, chert  Early to middle  Hazelton  Unconformity(?) Triassic(?)  middle sedimentary unit (3)  black s i l t s t o n e , limestone and f o s s i l i f e r o u s limestone, green and purple volcanic breccia, siltstone, sandstone, conglomerate, uiacke, polymictic pebble conglomerate  Wafic volcanic unit (2)  olivine porphyry basalt flows, augite porphyry basalt flows and pillowed flows, basaltic pyroclastic rocks, basaltic conglomerate, black s i l t s t o n e , sandstone, wacke, limestone  Lower sedimentary unit (1)  black s i l t s t o n e , a r g i l l i t e , shale, black wacke, sandstone, limestone  Formations and rock units as described by Alldrick et a l . , 1986, and Dawson and A l l d r i c k , 19B6. Numbers in parentheses are rock units as described in Figure 2.2.  7  'MP-182, 1S3  103P-160  103P-016  I03P-147  103P-223  F i g u r e 2.1. R e g i o n a l g e o l o g y s u r r o u n d i n g t h e D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. M o d i f i e d from A l l d r i c k e t a l . (1986), A l l d r i c k and Dawson ( 1 9 8 6 ) , and D e v l i n and Godwin ( 1 9 8 6 a ) .  8  LEGEND INTRUtlVI ROCKS  VOLCJkMC ANO lUNMCffTAJtV ROCKS [CONTINUED!  TUTUJtV  LOWER JURASSIC iCONTINUEDt  [ 9  \A  j MINOR DYKES: MICAOOlORITE (tl: GflANOOlORITe (Dt: LAMPROPHYRE (C)  | F E L D S P A R - M O R N B L E N D S PORPHYRITIC ANOESITIC PVROCLASTICS (41 AND FLOWS SILLS (Di: MINOR INTEMEDS OF LIMESTONE. SILTSTONE. SANDSTONE. CHERT. A N D BARITE ic)  1  |  8 1 AJAX INTRUSIONS: QUARTZ FELDSPAR PORPHYRITIC QUARTZ MONZONITE la): BJOTfTTi QUARTZ MONZONTTE (bl. S5.1 Ma(K-Afi  | 'y  | COAST PLUTONIC COMPLEX. QUARTZ MONZONITE GRAMOOtOfliTE IB). 43-51 Ma (KiArl  (•):  INTRUSIVE CONTACT  WLCAMC AMD SCOHMNTARV "JOCKS WODLC TO U f N I JURASSIC i~3  | 3 ] BASAL POLYMICTIC CONGLOMERATE. M I N O R I N T E R B E D D E D uMESTONE. SILTSTONE. GRlT SANDSTONE (al: SILTSTONE. ARGILLITE (01; sOLCANIC BRECCIA. MINOR I N T E R B E O O E D SILTSTONE. SANDSTONE Id. INTERBEDDED SILTSTONE. SANDSTONE. A N O ° £ B B L E CONGLOMERATE (MARKER -ORIZON) i d |  2 | AUGITE (OLIVINE) PORPHYRITIC BASALT FLOWS. P I L L O W E O FLOWS I«I, A U G l T E F E L O S P A R P O R P H Y R I T I C BASALT PYROCLASTICS AND KXCANtC BRECCIAS Itt: EPKXASTC CONGLOMERATE. MiNOR INTERBEDDED SILTSTONE. ARGILLITE. AND LIMESTONE !C|  |  1 j SILTSTONE. A R G I L U T E . WACKE fa):  1 BASAL FOSSILIFEROUS WACKE (tl: BLACK SILTSTONE ANO WACKE (M: MMOR INTHAPORMATONAL CONGLOMERATES AMO LIMESTONE (c)  U3WU JUHASSK I S I GREEN AND MAROON W X C A N C BRECCIA It); E P C L A S T C CONGLOMERATE AND SEDIMENTS (b): LOCAL DACITIC  FLOWS AND PVROCLASTCS (cl  RARE LIMESTONE <D»:  BOTTOM OF UNfT NOT SEEN  ^  90LD BELT ALTERATION ZONE  SYMBOLS VEIN M W E R A U Z A T W N STRATABOUND MINERALIZATION  _)  C R A C K L E B R E C C I A U IN E R A L I Z A T O N  *  P O R P H Y R Y MINERALIZATION  F i g u r e 2 . 2 . C r o s s - s e c t i o n f r o m F i g u r e 2.1 o f r e g i o n a l g e o l o g y s u r r o u n d i n g t h e D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. ( s e e F i g 2.1 f o r s o u r c e o f d a t a . )  9  Unit  3 i s a sedimentary  wacke, g r i t , breccia. contact unit  pebble  Unit  pers.  Unit  i n thickness  from  2 i s gradational.  comm. t o D. A l l d r i c k ,  flows  composition. thickness,  This hosts  occurrences  Unit  and/or  Fossils  5, i s g r a d a t i o n a l  a shallow  alternating  500 t o 2,000m i n gold  and b a s e  metal  area.  underlying  unit  4, and c o n s i s t s  water, marine t o s u b a e r i a l assemblage of g r e e n and maroon v o l c a n i c b r e c c i a s a n d  conglomerates, pyroclastics, thickness  with  with  of similar  of the s i l v e r ,  River  i n a g e (H.  sequence  sills  u n i t , which ranges from  i n the K i t s a u l t  c o l l e c t e d from  1986).  subvolcanic  the majority  volcanic  400 t o 2,000m and t h e  4 i s an a n d e s i t i c p y r o c l a s t i c r o c k  intercalated  of  unit  sandstone,  c o n g l o m e r a t e , and minor  3 p o s s i b l y a r e e i t h e r Permian o r T r i a s s i c  Tipper,  of  t o cobble  3 varies  against  sequence of s i l t s t o n e ,  lesser andesite with  of this  minor b l a c k unit varies  and/or d a c i t e siltstone from  flows and  and l i m e s t o n e .  l e s s than  The  100m t o a maximum  1,500m.  Unit  6, t h e u p p e r m o s t  marine assemblage of b l a c k sandstone, Jurassic Tipper,  limestone  fossils pers.  sequence exposed siltstone,  i n the area,  shale,  is a  wacke, w i t h  and i n t r a f o r m a t i o n a l c o n g l o m e r a t e .  from u n i t  lesser Early  6 ( D e v l i n a n d Godwin, 1986b; H.  comm. t o D. A l l d r i c k ,  10  1986) i n d i c a t e t h a t a  significant Jurassic  unconformity  (units  the K i t s a u l t  between T r i a s s i c  (units  4 t o 6) v o l c a n i c - s e d i m e n t a r y  valley  1 t o 3) a n d  units  may o c c u r i n  (H. T i p p e r , p e r s . comm. t o D. A l l d r i c k ,  1986).  2.3  TERTIARY INTRUSIVE UNITS  Several Hazelton  Tertiary  (7 TO 9)  intrusive  units  Group i n t h e K i t s a u l t  c u t a l l rocks of the  River area.  monzonite t o g r a n o d i o r i t e o f t h e E a r l y Range b a t h o l i t h , map-area  ( F i g . 2.1).  potassium-argon  Unit  i s exposed Carter  dates  and a b u n d a n c e  This  occurs  Arm i n t r u s i o n s  these  Ma  ( C a r t e r , 1982; r e c a l c u l a t e d constants  intrusions Alldrick  yield  from  (Alldrick,  satellite  Batholith.  intrusions,  which  because o f t h e i r  Arm a r e a  ( C a r t e r , 1982).  feldspar porphyritic  a potassium-argon  date  f r o m one  o f 55.1 + 3  i n Dawson and A l l d r i c k , 1986,  S t e i g e r and J a g e r ,  o l d e r dates  of the  quartz monzonite. B i o t i t e  of  using  yielded  Range  Eocene Ajax  as s m a l l s t o c k s o f q u a r t z  intrusions  Coast  (1982) r e p o r t e d 43 t o 51 Ma  i n the A l i c e  q u a r t z monzonite and b i o t i t e  Eocene  i n t h e southwest corner  t o Middle  named A l i c e  proximity unit  t o Middle  f o r t h e e a s t e r n Coast  8 i s the Early  were o r i g i n a l l y  U n i t 7, q u a r t z  than  1977).  the Coast  Although  Range  p e r s . comm., 1987) i s c e r t a i n  plutons or " o u t l i e r s "  Batholith.  11  o f t h e main C o a s t  Ajax  Batholith, t h a t they a r e Range  Unit units  9 i s the  i n the  numerous T e r t i a r y d y k e s t h a t  Kitsault  River  area.  l a m p r o p h y r e , m i c r o d i o r i t e and dykes y i e l d e d a whole rock and  Godwin,  2.4  STRUCTURE  sedimentary  2.2).  r e g i o n a l f o l d s are  units  These f o l d s ,  Glacier  anticline,  anticline. Earlier  date of  One  22.3  basalt,  of  + 0.8  a l l rock  the Ma  basalt  (Devlin  1986b).  Three p a r a l l e l and  They c o n s i s t o f  granodiorite.  K-Ar  crosscut  Two  faults  i n the  Kitsault  identified  i n the  River  ( F i g s . 2.1  a l l doubly plunging, Kitsault  major trend  River  s e t s of  area  include  s y n c l i n e and  faults  n o r t h w e s t and  the  the  also transect  younger f a u l t s  volcanic and  Varden  Mount the  McGuire  area.  trend  northeast.  2.5  ALTERATION  An  extensive  hydrothermal  gold-silver-copper northwest nearly  fault  15km  Kitsault  greenschist  trend  and  River  and  area  zone h o s t i n g  s u b p a r a l l e l to  This  alteration  i s c h a r a c t e r i z e d by  pyritization.  Alldrick,  metamorphism.  Prehnite  12  was  to  1986)  f a c i e s (P. Read, p e r s .  numerous the  zone m e a s u r e s  sericitization,  A l l Hazelton  have been s u b j e c t e d  f a c i e s (Dawson and  prehnite-pumpellyite regional  trends  ( F i g . 2.1).  i n length  silicification the  occurrences  alteration  Group r o c k s either or  comm.,  identified  in  by  1986) the  writer  in  some t h i n is  favored  sections  (section  f o r the Hazelton  3.2) Group  area.  13  and t h e l o w e r m e t a m o r p h i c rocks  i n the K i t s a u l t  grade  River  3.0  3.1  PROPERTY GEOLOGY  INTRODUCTION  Geology o f t h e D o l l y (in  p o c k e t ) , and F i g u r e s 3.4 and 3.5  descriptions the  of geology  general geology  more d e t a i l e d (Campbell, mine  i n the area  by S k e r l  geological  (1962) and M i t c h e l l  Belt  area  northwest  Geology of the Kinskuch  accounts of ( 1 9 7 3 ) , and silver  mine  of the T o r b r i t silver  Lake a r e a ,  V a r d e n camp, was mapped by G a l e  t o 3.3  Previous  include brief  1956; C a r t e r , 1 9 7 0 ) , and t h e Wolf  1986).  the Dolly  ( i ntext).  r e p o r t s on: the T o r b r i t  1959), t h e G o l d  (Calich,  (Thiersch, of  V a r d e n camp i s i n F i g u r e s 3.1  prospect. 12km e a s t  (1957).  R o c k s i n t h e map-area a r e c h a r a c t e r i z e d by t h e E a r l y t o Middle  Jurassic  volcanic  Hazelton  and s e d i m e n t a r y  volcanogenic  Group, c o n s i s t i n g rocks with  sulfide/sulfate  a s s o c i a t e d s t r a t i f o r m and  deposits.  3,000m o f v o l c a n i c f l o w , p y r o c l a s t i c exposed these  Hazelton  The based  i n the Dolly Group  Hazelton  Tertiary  rocks  dykes c u t a l l o f  rocks.  Group r o c k s have been s u b d i v i d e d i n t o  position  relative  horizon.  Rock names u s e d  from  petrography  both  There a r e approximately  and s e d i m e n t a r y  Varden map-area.  on m i n e r a l o g i c a l and t e x t u r a l  stratigraphic  p r i n c i p a l l y of  characteristics,  to the m i n e r a l i z e d  to describe the units  and whole r o c k  14  chemistry.  units  and on  stratiform  were d e r i v e d Petrography  of  the  volcanic  summarized  and  sedimentary  i n Table  3.1.  rocks  i n the  Textural  f r a g m e n t s and  deposits,  inferred  reconstructed  from p r e s e r v e d  i s consistent  with  terminology (1984). discussed  The consists  in detail  in section  stratigraphic of  hangingwall volcanic sedimentary 1,200m o f  rocks.  2b).  mineralization  (units  rocks,  and  consist  of  pale  andesite 6b),  lapilli  by  tuff  sedimentary  (unit  9)  afe  not  and  3c)  i s up  to  60m  thick.  overlies  and  by of  (unit  more  1),  (unit  7b).  6a),  the  than  g r e e n _+ shard  are  tuff  about  ash (unit  15  1,000m  tuff  (unit  5),  (unit  7a)  and  Hangingwall volcanics  shown i n F i g u r e  volcanic  dark  dark green andesite  andesite  8a,  footwall  Hangingwall  mineralization  ash-lapilli  (units  footwall  green andesite  grey b a s a l t i c - a n d e s i t e  (unit  rocks  tuff  3.6,  silver-lead-zinc-barite  grey-green p o r p h y r i t i c  a n d e s i t e ash  2a)  and  tuff  is  in Figure  rocks consist  3b  maroon b a s a l t i c - a n d e s i t e  the  Schmincke  a l l overlain  3a,  stratiform  and  bounded by  volcanic  (unit  Stratiform  r o c k s above the and  summarized  which are  andesite  and  igneous rocks  g r e e n +_ maroon b a s a l t i c - a n d e s i t e  (unit  volcanic  rocks,  textures  Fisher  the  mineralization  Footwall  maroon p o r p h y r i t i c tuff  of  either  3.3.  sequence,  stratiform  of  is  of  however, were  that  Chemical c l a s s i f i c a t i o n  V a r d e n camp  characteristics  pyroclastic or  Dolly  8b  and 3.6.  8c).  are  Tertiary  4), grey  tuff  pale  thick,  (unit  green overlain  dykes  TABLE 3.1. Petrography! of the volcanic and sedimentary rocks In the Dolly Uarden camp, northwestern B.C.  Unit  Rock  Intrusive and flow rocks Pyroclastic and sedimentary rocks Total Total Fragments (percent of total) phenocrysts Phenocrysts (percent of total) Groundmass fragments Crystal fragments Uitric Lithic matrix (percent of rock) PL HB C/PX QZ OP AP SP F5 C/PX QZ CH CA SC EP (percent of rock) PL HB C/PX QZ BI PIS OP SP fragments fragments FS QZ CH CA SC  9 Basalt and lamprophyre dykes Be Black siltstone and shale 8b Calcareous and fossiliferous uacke 8a Maroon siltstone 7b Pale green andesite ash tuff 7a Grey-green porphyritic andesite 6b Dark green andesite tuff I— 6a Oark grey andesite lapilli tuff 5 Maroon basaltic-andesite ash-lapilli tuff 4 Pale grey basalticandesite ash tuff 3 Mineralized stratiform horizon 2b Green andesite shard tuff 2a Green + maroon porphyritic andesite 1 Green • maroon andesite tuff  20-90  35-55  SO 30  65 20  15  5  S tr  10  tr  80-100  65  25  BO AO  50 30  20 3 tr 7 tr 45 tr 5 20  20-40  50  30  40-60  40  5  45  25  2  65  25-75  50  15  30  30-40  4  40  20  10  tr  10  45  x tr tr  J  n/a  30-65  80  5  5  tr 10 tr tr  30  20  25  15  n/a  x tr  30-70  55  •  30-60  25 tr  • tr 10  65  1. Mineral assemblages estimated from thin sections of each rock unit. Abbreviations: QZ = quartz, PL = plagioclase, C/PX = clinopyroxene, HB = hornblende, BI = biotite, PIS = muscovite, AP = apatite, SP = sphene, OP = opaques, FS = undifferentiated feldspar, SC = sericite, CH = chlorite, CA = undifferentiated carbonate, EP = epidote, x = pervasive, • = minor, tr = trace, n/a = not applicable (unit 3 is described in Table 3.2).  F i g u r e 3.4.  Geology of the  northwestern B.C. and  3.3  the  Early  D o l l y Varden camp, A l i c e Arm  C r o s s - s e c t i o n s A-B  ( i n p o c k e t ) , and  3.5  (in text).  not  shown.  p o r p h y r i t i c a n d e s i t e ) , . and Mineralized  3b  u n i t 2b  = u n i t 4 (pale grey b a s a l t i c - a n d e s i t e ash-lapilli  t u f f ) , u n i t 6b  u n i t 8b  tuff).  Sediments (4)  ( c a l c a r e o u s and  s i l t s t o n e and  17  (green +_ maroon tuff).  (silica-sulfide exhalite),  and  volcanics  t u f f ) , unit 5  t u f f ) , u n i t 6a  and  u n i t 7b  = u n i t 8a  (dark grey  (pale  (maroon  f o s s i l i f e r o u s wacke), and  shale).  = unit 1  (dark green a n d e s i t e t u f f ) ,  (grey-green p o r p h y r i t i c a n d e s i t e ) ,  a n d e s i t e ash  Tertiary  Hangingwall ash  3.2  within  (green a n d e s i t e shard  (sulfate-oxide-sulfide exhalite).  andesite l a p i l l i  (1)  t u f f ) , u n i t 2a  (carbonate-sulfate-sulfide  (maroon b a s a l t i c - a n d e s i t e  7a  A l l u n i t s are  s t r a t i f o r m h o r i z o n (2) = u n i t 3a  exhalite), unit  (3)  are on F i g u r e s  Footwall volcanics  (green _+ maroon b a s a l t i c - a n d e s i t e  3c  C-D  to Middle J u r a s s i c Hazelton Group, except  dykes, which are  unit  and  area,  unit  green  siltstone),  u n i t 8c  (black  18  F i g u r e 3.5. C r o s s - s e c t i o n s f o r the D o l l y Varden camp, northwestern B.C. C r o s s - s e c t i o n A-B, looks northwest through the D o l l y Varden West, N o r t h s t a r and T o r b r i t areas. C r o s s - s e c t i o n C-D, looks northwest through the Wolf d e p o s i t . L o c a t i o n and u n i t s are d e s c r i b e d i n F i g u r e 3.4.  19  EAST  8c 8c" -8b© -  -  -  F i g u r e 3.6. G e n e r a l i z e d s t r a t i g r a p h i c c o l u m n f o r r o c k u n i t s i n t h e D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. U n i t s a r e l o c a t e d and described i n Figure 3.4.  20  3 .2  LITHOLOGY  3.2.1  Footwall Volcanic  Rocks  Unit 1 Green the  s o u t h e a s t c o r n e r o f t h e map-area  appears an  + /- maroon b a s a l t i c - a n d e s i t e  t o be  indefinite  map-area. blocky,  the o l d e s t  Outcrops  angular f r a c t u r e  bedding  and  I n hand  specimen,  lesser hand  patterns.  and  Varden  cliffs  lapilli  1 is typically  Numerous b r o k e n  camp.  I t has i n the  exhibiting  surfaces, locally  up  show  t o 3cm  across.  green w i t h minor  maroon,  plagioclase  maroon c l a s t s ,  in  3.4),  i s not exposed  Weathered  t o subrounded  1), exposed  crystals,  are e a s i l y  and  recognizable in  specimen.  60  range The  unit  d a r k g r e e n and  In t h i n to  massive  3.1  p a l e g r e y w i t h maroon t i n t s ,  subangular  fine-grained.  i t s bottom  are g e n e r a l l y  (unit  (Figs.  i n the D o l l y  t h i c k n e s s because  characteristically  and  unit  tuff  section,  the t u f f s  p e r c e n t randomly from  less  than  t o 15mm  but average  of these fragments  ashfall  rather  1984).  Subhedral, p l a g i o c l a s e  comprise  t h a n an a s h  flow o r i g i n  (An5).  approximately hornblende  10  o f between  Anhedral hematite  indicate and  and  amounts.  that  an  Schmincke,  They a r e a l b i t e g r a i n s make  30  across.  w i t h many b r o k e n  p e r c e n t of the fragments,  i s p r e s e n t o n l y i n minor  1.5mm  might  (Fisher  crystals  25 p e r c e n t o f t h e f r a g m e n t s .  composition  1 consist  o r i e n t e d , m a t r i x supported fragments  0.1mm  random o r i e n t a t i o n  of u n i t  faces,  in  up  subhedral Subangular  ash  and  crystal  tuff clasts  component. and  plagioclase carbonate,  lesser  quartz.  analysis  M i n e r a l pseudomorphs i n c l u d e  carbonate  oxides.  r e p l a c e d by  and/or q u a r t z  veinlets  a r e common.  a basaltic-andesite  3.33 and 3.34; W i n c h e s t e r  unit  1 ( T a b l e 3.3:  composition  (Figs.  a n d F l o y d , 1977, L e B a s e t a _ l . , 1 9 8 6 ) .  2 Unit  (unit  2 i s r e p r e s e n t e d by e i t h e r  2a) o r t h e i r p y r o c l a s t i c  Porphyritic  andesites of unit  maroon t u f f s o f u n i t  2a i n t r u d e u n i t  reaching  a maximum  moderately fracture grey;  throughout  and d i s p l a y  maroon t i n t s .  unit  1, a n d b o t h  units  t u f f s of unit  2b,  andesite  (Unit  2a) c r o p s o u t  t h e s o u t h e a s t e r n p a r t o f t h e map-area  p a t t e r n s as u n i t  when f r e s h ,  by s h a r d  t h i c k n e s s o f n e a r l y 150m.  resistant  sills  5 ( F i g . 3.6).  G r e e n +/- maroon p o r p h y r i t i c sporadically  s u b v o l c a n i c d y k e s and  equivalents (unit 2b).  1 and 2a a r e u n c o n f o r m a b l y o v e r l a i n and  o f c h l o r i t e and/or  o f one s p e c i m e n f r o m  3.3) i n d i c a t e s  of c h l o r i t e  a l t e r i n g t o c h l o r i t e and i r o n  Randomly o r i e n t e d 0.2mm i n w i d t h ,  o f t h e fragment  primarily  fragments have been c o m p l e t e l y  Chemical  Unit  consists  to f i n e aggregates  and h o r n b l e n d e  carbonate.  section  with  going  lithic  averaging  up t o 65 p e r c e n t  The f i n e a s h m a t r i x  carbonate  Many  comprise  1.  t h e same b l o c k y  angular  S u r f a c e s weather a p a l e  2a i s p a l e g r e e n  The groundmass  Outcrops are  t o grey-green  i s aphanitic  22  t o medium with  and p h e n o c r y s t s ,  local  generally  1mm  chloritized  a c r o s s , are dominantly  mafic  epidotization color. hand and  specimen,  width,  disseminated imparts  quartz with  are  and  of p l a g i o c l a s e  Finely  minor  minerals  s h a l l o w emplacement  hematite  magnetite,  a marked m a g n e t i s m  or e x t r u s i o n ) are  epidote, quartz  and  section);  up  disseminated  to 2 percent  to t h i s  than  t r a c e s of p r e h n i t e  in  Calcite 1mm  in  indicative  with  pyrite  green  observed  rock.  less  (possibly filled  chlorite,  the pale  directly  veins, averaging  lesser  Extensive  imparts  not  Common a m y g d u l e s  with  flecks.  phenocrysts  barite  numerous.  plagioclase  of  calcite, (in thin  i s present  locally.  Thin with  s e c t i o n s of u n i t  lesser  trachytic  phenocrysts,  30  0.1mm  and  t o 5mm  consist  o f : 80  and  t o 65  2a  percent  (rarely  pyroxene,  10  iron  in size.  up  with  amounts o f  e p i d o t e and  carbonate.  sericite  by  that partly  around hornblende iron  and  These  aggregates  quartz  and  (An23 t o A n 2 7 ) ,  show a l t e r a t i o n  23  of  are  of carbonate,  oxides.  magnetite), The  chlorite,  feldspar,  r e p l a c e most p h e n o c r y s t s pyroxene  than  phenocrysts  leucoxene.  Plagioclase crystals clots  less  percent), 5 percent  sphene and  sericite,  irregular  Subhedral  (mainly anhedral  of m i c r o g r a n u l a r  lesser  indicated  t o 70  oxides  t r a c e s of q u a r t z , a p a t i t e ,  groundmass c o n s i s t s  porphyritic  range from  c r u d e l y zoned p l a g i o c l a s e  hornblende  as  of the rock,  1.0mm  5 percent  and  predominantly  intergranular textures.  percent  average  percent  exhibit  and  sparse  saussuritized  epidote  and  ( F i g . 3.7). to c h l o r i t e  Rims and  I F i g u r e 3.7. S a u s s u r i t i z e d p l a g i o c l a s e p h e n o c r y s t s i n g r e e n +/maroon p o r p h y r i t i c a n d e s i t e ( u n i t 2 a ) . Width o f photomicrograph i s 4.6mm ( p o l a r i z e d l i g h t ) .  F i g u r e 3.8. V i t r i c - s h a r d f r a g m e n t s i n g r e e n a n d e s i t e s h a r d t u f f (unit 2b). Note t h a t fragments are a l i g n e d s u b p a r a l l e l t o t h e foliation direction. W i d t h o f p h o t o m i c r o g r a p h i s 4.6mm (polarized l i g h t ) .  24  Green a n d e s i t e shard pyroclastic River  and  (Figs. the  rock  that crops  T i g e r Creek,  3.1  and  3.4).  Moose-Lamb a r e a  West a r e a .  Outcrops  displaying Weathered fresh  a pitted  out  2b)  near  is a  the  This unit  ranges  t o a maximum of  170m  map-area  finely  in  Varden  grey  or  jointing.  grey-brown;  w i t h m i n o r maroon  and  15m  s u r f a c e s , commonly  s o r t e d and  fragments  Minor  p a r t of the  i n the D o l l y  pale grey,  a r e unbedded, m o d e r a t e l y  fine-grained matrix.  Kitsault  regular, subparallel  to grey-green  crystal  of  i n t h i c k n e s s from  have smooth, r o u n d e d s u r f a c e and  widespread  confluence  southeastern  surfaces are e i t h e r  small plagioclase a  (unit  i n the  s u r f a c e s are grey  Deposits  tuff  tints.  tuffaceous  dark  green  disseminated  with  shards pyrite  set i n occurs  locally.  Thin  s e c t i o n s show t h a t f r a g m e n t s  supported  and  between 30 0.1mm  15  and  t o 10mm  percent  percent  of t h i s  and  average  1.0mm  tuff  ilmenite),  fragments,  S h a r d s and  subangular. the  component. primarily  plagioclase  minor hornblende  muscovite.  crystals,  and  lithic  25  comprise  percent  and  less  than  composed o f platy  55  shards,  (probably t r a c e s of  are g e n e r a l l y  grains are  locally  of a minor matrix  g r a i n s of c h l o r i t e  25  matrix  r a n g e from  They a r e  pyroxene,  vitroclastic  s m a l l , ragged  and  opaques  fragments  2b a r e  Fragments  in size.  possible contribution original  unit,  5 percent  lithic  Subrounded  The by  oriented.  70  subhedral  percent  suggest  preferentially  in unit  abundant  and  epiclastic is replaced and  sericite  with  minor carbonate  and  quartz.  h a v e been r e p l a c e d  by  either  whereas most s h a r d and chlorite. chlorite  rimmed by  0.2mm i n w i d t h , a r e  Welding of  in unit  c r y s t a l and  developed  not  well  (Fisher  3)  2b  as  expected  Schmincke,  Chemical a n a l y s i s (Table  3.3:  section  3.33  and  also  obtained  date,  3.34).  too  regional  3.2.2  young  2)  by:  a  1)  in andesitic  to  averaging  unit.  preferred  strung-out  of  four  samples  orientation  to  a  crudely  glassy-looking  Shard o u t l i n e s volcanic  from u n i t s  show them a l l t o be  sample from  d a t e of unit  2a.  f o r H a z e l t o n Group r o c k s ,  Stratiform  this  subparallel  fragments.  A w h o l e r o c k K-Ar  metamorphism  altered  are  rocks  1984).  3.3),  f o r one  generally  by  Calcite veinlets,  i s evidenced  ( F i g . 3.8),  or c h l o r i t e ,  replaced  abundant throughout  flattened vitric  defined, and  iron oxides.  generally  carbonate  fragments are  pyroxene are  locally  fragments  and  v i t r i c - s h a r d fragments,  foliation  m a t r i x and  sericite  lithic  H o r n b l e n d e and and  Plagioclase  (section  and  2b  andesitic  (Figs.  +_ 2.5  was  72.2 This has  2a  Late  Ma  Cretaceous  been r e s e t  by  4.3).  Silver-Lead-Zinc-Barite  Exhalative  Mineralization  Unit  3 The  r o c k s of  enclosing  unit  3 are  w a l l r o c k s and  host  typically  layered,  significant silver  26  conformable and  base  with  metal  mineralization. volcanogenic the  T h e y a r e i n t e r p r e t e d h e r e as a  silver-lead-zinc-barite  following deposits  (Figs.  south  Torbrit,  South Musketeer exhibits quartz  (unit  and p o s s i b l y K i t s o l .  sulfates  (unit  3c) i n t h e T o r b r i t  summarized  i n Table  3c,  barite,  Silver across  from u n i t  values  c h a r a c t e r i z e d by t h e h i g h 3a) high  that averages  averaging  405g s i l v e r  massive  and  area.  zoning  i n the  i n Table  in  3a, t h r o u g h u n i t steadily  3.2.  percentages of  3b, t o u n i t  i n c r e a s e , whereas  i n abundance.  horizon also exhibit  zoning  from west t o e a s t i s  grade D o l l y Varden East  865g s i l v e r  grade N o r t h s t a r  oxides  clearly  increases  decrease  The z o n i n g  layer  by p e r c e n t a g e d e c r e a s e s  i n the s t r a t i f o r m  the property.  River,  ( u n i t s 3a, 3b and 3c) i s  shows t h a t  and s u l f i d e s  occurrence  3b) i n t h e N o r t h s t a r and  i s demonstrated  j a s p e r and i r o n o x i d e s  carbonate  East,  through  and Moose-Lamb  i s accompanied  Moving  area,  Property-scale mineral  presented  minerals  minerals.  quartz,  3.2.  mentioned above,  summary d a t a  other  and e a s t  stratiform  sulfates,  horizon  hosts  from m a s s i v e s u l f i d e s and  (unit  to laminated  of the s t r a t i f o r m  certain  This  zoning  and s u l f i d e s  Mineralogy  exhalite,  isolated  3a) i n t h e D o l l y V a r d e n E a s t  V a r d e n West a r e a ,  sulfides  of  to north  that  s i d e of the K i t s a u l t  property-scale mineral  carbonates,  The  and west  Moose-Lamb, a s m a l l ,  o f T i g e r C r e e k on t h e e a s t  Dolly  exhalite horizon  3.1 and 3 . 4 ) : D o l l y V a r d e n West, D o l l y V a r d e n  Northstar, north  from  stratiform,  deposit  (unit  per tonne, t h r o u g h t h e moderate t o  and T o r b r i t  deposits  ( u n i t s 3b and 3c)  per tonne, t o t h e lower grade  27  Moose-Lamb  TABLE 3.2. dineralogyl of the stratiform horizon (unit 3) in the Dolly Warden Camp, northwestern B.C. Property-scale mineral zonation is shown by increases in barite, jasper and iron oxides accompanied by decreases in quartz, carbonate and sulfides, mowing from the silica-sulfide exhalite (unit 3a) , through the carbonate-sulfate-sulfide exhalite (unit 3b), to the sulfate-oxide-sulfide exhalite (unit 3c).  Unit  Rock name  3c  Sulfate-oxidesulfide exhalite Carbonate-sulfatesulfide exhalite Silica-sulfide exhalite  3b 3a  1.  Gangue mineralogy (percent of total) QZ SC CH EP CA SO RH BA JA  35  2  30 70  10  15  5  40  1Q  15 tr  tr  5  7  Ore mineralogy (percent of total) PY SL GN CP HE mG TT PR AR Ag  a  3  1  +  5  7  3  +  20  +  8  5  tr  tr  tr tr  tr  tr  tr  Percent mineralogy is estimated from polished thin sections of stratiform ore samples. Abbreviations: QZ = quartz, SC = sericite, CH = chlorite, EP = epidote, CA = calcite, SO = siderite, RH = rhodochrosite, BA = barite, JA = jasper, PY = pyrite, SL = sphalerite, GN = galena, CP chalcopyrite, HE = hematite, MG = magnetite, TT = tetrahedrite, PR = pyrargyrite, AR = argentite, Ag = native silver, + = minor, tr = trace.  28  deposit  (unit  3c) t h a t  averages  from  the high  grade D o l l y  westward silver  grade decreases  V a r d e n West d e p o s i t stratiform deposit, and  horizon  generally  Stratiform footwall  3b).  ranges  from  per tonne.  Varden East  t o 15g s i l v e r  (unit  t o 15,000:1  135g s i l v e r  to gold  i n the D o l l y  averages greater  exhalative  and h a n g i n g w a l l  than  (units  o v e r l a i n by t h e maroon t u f f s  and  sulfide exhalite  carbonate-rich  o r e ( u n i t 3b) a t t h e N o r t h s t a r  from  l e s s than  typically  Silica-sulfide of  (Figs.  stratiform deposits  varies  exhalite  deposits  stained  jarosite.  average about  layering  c a n be o b s e r v e d  i n outcrop  mineralogy  i s characterized  lensoidal,  fine-grained,  hosted  predominantly and o l d Outcrops  limonite, p a r t i c u l a r l y often  ( F i g . 3.9).  convoluted, Hand  specimen  by d i s s e m i n a t e d , m a s s i v e and  p y r i t e with  i n a gangue o f medium  20m.  ( D o l l y Varden E a s t ) .  j o i n t i n g and d i s t i n c t ,  grained,  29  3.1  i n the D o l l y  i n trenches  o r a n g e - y e l l o w due t o a b u n d a n t Regular  60m  ( u n i t 3a), comprised  V a r d e n mine  unit  underlies deposit  q u a r t z and p y r i t e , i s e x p o s e d m a i n l y  stopes of the D o l l y are  and.also  5m a t t h e T o r b r i t mine t o n e a r l y  V a r d e n West a r e a ;  with  Quartz  interbedded with  Varden East  of these  deposits,  5 ( F i g . 3.6).  ( u n i t 3a) i s commonly  The t h i c k n e s s  West  2b a n d 4, r e s p e c t i v e l y ) ,  4 a t the D o l l y  3.4).  f o r the  (unit 3), together  of u n i t  deposit,  ratio  1,000:1.  mineralization tuffs  the  Varden  i n t h e T o r b r i t and Moose-Lamb  are  and  deposit,  per tonne f o r the D o l l y  The s i l v e r 20:1  Moving  traces  of  chalcopyrite  grey with minor  milky  white, quartz  ( F i g . 3.10).  stringers  common and  are  Polished of  70  quartz,  minor c h a l c o p y r i t e traces tuff  of  percent  epidote  anhedral grains strain,  indicates  layers.  and  A n h e d r a l and  less frequently diameter  or  sulfide  to  unit  3a  is  percent  5 percent native  comprise  sericite,  rarely),  silver.  and  Angular  i n some s p e c i m e n s .  g r a i n boundaries which Sericite  occurs  Quartz  concentrated  isolated grains, Layering,  axial-plane  probably  either  in finer  grained  s u b h e d r a l p y r i t e forms m a s s i v e  ( F i g . 3.11).  weakly c r e n u l a t e d  generally  aggregates  l e s s than  p r o b a b l y b e d d i n g , as  foliation  was  identified  1.0mm well  a  i n some  sections.  Carbonate-sulfate-sulfide primarily  of  represented Weathered as  p y r i t e , 10 (up  polygonal  to quartz  and  d i s p l a y i n g both undulose e x t i n c t i o n ,  recrystallization.  interstitially  thin  showed t h a t  a r g e n t i t e , p y r a r g y r i t e and  as  denoting  in  and  study  fragments have been i d e n t i f i e d  occurs  and  20  quartz  abundant.  thin section  percent  Cross-cutting  well  observed  i n the surfaces  as  generally  locally  quartz,  i n only  pyrite-rich  siderite,  d i s p l a y the  3b),  sulfides,  Northstar  deposits.  same l i m o n i t e  a few  outcrops, core  mineral  b a s e , and  than those of  from  s t a i n as  unit  3a.  i s pronounced the  zonation  Northstar  ( F i g . 3.13)  a sphalerite-galena-rich 30  consisting  b a r i t e and  a b u n d a n t manganese c o a t i n g s .  in d r i l l  Vertical  (Unit  D o l l y V a r d e n West and  more r e c e s s i v e  w o r k i n g s and 3.12).  calcite,  exhalite  unit  Outcrops  is  3a, are  Layering, i n underground  deposit  (Fig.  c o n s i s t i n g of top  a  F i g u r e 3 . 9 . S t e e p l y - d i p p i n g l a y e r s of s u l f i d e s , mostly p y r i t e , i n s i l i c a - s u l f i d e e x h a l i t e ( u n i t 3a) f r o m t h e D o l l y V a r d e n E a s t deposit. L e n s cap i n c e n t e r o f p h o t o g r a p h t o be u s e d f o r s c a l e i t i s a p p r o x i m a t e l y 5cm a c r o s s .  31  I F i g u r e 3.10. P o l i s h e d s l a b o f q u a r t z and p y r i t e m i n e r a l i z a t i o n , t y p i c a l of the s i l i c a - s u l f i d e e x h a l i t e ( u n i t 3a).  F i g u r e 3.11. A n h e d r a l p y r i t e f o r m i n g m a s s i v e a g g r e g a t e s and crudely developed layers i n s i l i c a - s u l f i d e e x h a l i t e (unit 3a). W i d t h o f p h o t o m i c r o g r a p h i s 7.0mm ( p l a n e , r e f l e c t e d l i g h t ) .  32  F i g u r e 3.12 L a y e r s o f c a l c i t e , q u a r t z , b a r i t e and s u l f i d e s i n c a r b o n a t e - s u l f a t e - s u l f i d e e x h a l i t e ( u n i t 3b) f r o m u n d e r g r o u n d workings a t the N o r t h s t a r d e p o s i t . D i r e c t i o n of bedding i s i n d i c a t e d by hammer. y  33  has  a l s o been r e c o g n i z e d  deposit  (Thompson and  disseminations galena,  with  Pearson,  stringers  lesser  coarse-grained carbonate,  and  in d r i l l  and  pyrite locally  q u a r t z and  barite  3b  in polished thin  calcite,  30  percent  3 percent  5 percent  galena,  rhodochrosite, to  subhedral  in  (Fig.  The  i s c u t by  principally  contains  percent  40  siderite,  and/or w i t h e r i t e ,  bladed  comprising  occur  crystals,  f o r the other m i n e r a l s , during or  t o be  7  percent  5 percent  either  pyrite,  trace  fractures.  Anhedral as  or d i s s e m i n a t e d  as up  and  average  t o 1.0cm  of b a r i t e  exhalite  (unit  barite,  and  calcite  polygonal indicative  or  This  quartz.  3c), containing  hematite,  jasper  t h e most e x t e n s i v e o f t h e  M i n e , t h e Moose-Lamb, t h e  34  1.0mm  i n length  i s probably  of e i t h e r  grains.  coarse-grained,  the m i n e r a l i z e d s t r a t i f o r m  the T o r b r i t  percent  subsequent t o d i a g e n e s i s .  numerous v e i n l e t s  appears  and  within a  tetrahedrite,  along  coarse-grained nature  quartz, c a l c i t e ,  layers,  manganiferous  s u l f i d e minerals occur  Sulfate-oxide-sulfide  include  10  however, can  to euhedral,  of r e c r y s t a l l i z a t i o n  facies  section  massive aggregates  Barite,  3.15).  sulfides,  occur  t h e g r a i n s have p o l y g o n a l o u t l i n e s  grain boundaries  unit  chalcopyrite,  rare native s i l v e r  layers,  diameter.  subhedral  fine-grained sphalerite  m i n o r c h a l c o p y r i t e and  and  Northstar  ( F i g . 3.14).  barite  gangue and  monomineralic Generally,  quartz,  the  I n hand s p e c i m e n ,  vuggy gangue o f  Unit  sphalerite,  from  1981).  of  and  core  and  three deposit  horizon. South  Examples  Musketeer,  and  possibly the K i t s o l  are  g e n e r a l l y s m a l l , and r e c e s s i v e .  characteristically bedding,  with  abundant,  quartz,  the u n i t  brecciation. is distinctly  unit  crudely  (Figs.  rhythmic  a  t h e same l a m i n a t e d  fine-grained jasper-rich  Unit  barite  o f 35 p e r c e n t  siderite,  percent  sphalerite,  chalcopyrite, tetrahedrite. but  1959). the  are  finer  fragments,  b u t r o t a t e d and s e t i n locally.  15 p e r c e n t  calcite,  hematite,  15  7 percent  4 percent  chlorite,  mineralogy percent jasper, 5  pyrite,  1 percent  galena,  3 minor  and t r a c e s o f p y r a r g y r i t e , a r g e n t i t e and Overall grain size subhedral  and c a r b o n a t e ,  same p o l y g o n a l ,  observed  i n the  s e c t i o n , has a d i v e r s e  i s generally less barite  B a r i t e c o n t a i n s up t o 1 p e r c e n t Quartz  repeated  were o b s e r v e d  magnetite,  2 percent  exhibit  as r e c o g n i z e d  mineralogy,  quartz,  5 percent  many c o a r s e - g r a i n e d ,  length.  are  m a g n e t i t e and  d e f i n e d by  Subangular  and/or w i t h e r i t e , 8 p e r c e n t  percent  reflecting  the laminations  triplets,  matrix,  3c, i n p o l i s h e d t h i n  consisting  surfaces  layering,  hematite,  layering  and Moose-Lamb d e p o s i t s .  displaying  3c  reddish-maroon.  Locally,  sulfide-sulfate-oxide mineral Torbrit  Weathered  Where j a s p e r a n d h e m a t i t e  carbonate,  17 and 1 8 ) .  developed  outcrops, of u n i t  3c g e n e r a l l y c o n s i s t s o f l a m i n a t i o n s o f  jasper, barite,  sulfides  Sporadic  d i s p l a y a w e l l developed  local  Megascopically,  prospects.  probably  i n u n i t s 3a and 3b. g r a i n e d than  laths  than  1.0mm  a r e up t o 2cm i n  strontium  (Campbell,  a s w e l l as some b a r i t e , d i s p l a y recrystallized, Sulfides,  hematite  t h e gangue m i n e r a l s  35  grain  boundaries  and m a g n e t i t e  and l o c a l l y d i s p l a y  F i g u r e 3.13. V e r t i c a l z o n a t i o n i n d r i l l h o l e U-80-95 i n N o r t h s t a r d e p o s i t , D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. U n i t 2a = g r e e n +_ maroon p o r p h y r i t i c a n d e s i t e , p o s s i b l e s i l l ; u n i t 2b = g r e e n a n d e s i t e s h a r d t u f f ; u n i t 3b-1 = w h i t e , coarse-grained b a r i t e > q u a r t z >> c a l c i t e w i t h l e n s e s o f p y r i t e ; u n i t 3b-2 = s i d e r i t e >> c o a r s e - g r a i n e d p y r i t e > q u a r t z ; u n i t 3b-3 = w h i t e , coarse-grained quartz > c a l c i t e > coarse-grained, bladed b a r i t e ( p o s s i b l y some w i t h e r i t e ) , n a t i v e s i l v e r a l o n g f r a c t u r e s ; u n i t 3b-4 = l a m i n a t e d s u l f i d e s ( s p h a l e r i t e > g a l e n a ) > q u a r t z > coarse-grained, bladed b a r i t e ; u n i t 4 = pale grey b a s a l t i c - a n d e s i t e a s h t u f f , p y r i t e and q u a r t z f r a g m e n t s ; u n i t 5 = maroon b a s a l t i c - a n d e s i t e a s h - l a p i l l i t u f f w i t h m i n o r s h a r d s , l a p i l l i and e x t e n s i v e c a r b o n a t e a l t e r a t i o n . Note t h a t v e r t i c a l z o n a t i o n i s e x p r e s s e d by s y s t e m a t i c v a r i a t i o n i n o r e m i n e r a l o g y g o i n g f r o m u n i t 3b-1 t o 3b-4.  36  F i g u r e 3.14. P o l i s h e d s l a b o f c a l c i t e , b a r i t e and sphalerite m i n e r a l i z a t i o n , t y p i c a l of the carbonate-sulfate-sulfide e x h a l i t e ( u n i t 3b). " "  37  colloform  layering  minerals  as  well  ( F i g 3.16).  as  colloform  C h l o r i t i z e d s h a r d s and  fragments  have been r e c o g n i z e d  specimens  from  calcite  3  isotope  (section  deposited  as  data  4.2)  from  be  The  Cross-cutting  secondary  some  the  gangue m i n e r a l s  exhalites  probably  discussed  of  of  were  in a  this mineralization  further  i n chapter  and  5.  Rocks  4  5 to  85m  horizon  in thickness, (units  West) and  recognized stain  as  to w e l l  3a  and  3a  developed pale  Most o r i g i n a l  and  underlying  3b,  g r e y on features  pyritic  and  are  ( u n i t 4),  mineralized  only. the  of  Dolly  Varden  Outcrops are  (East  easily  same o r a n g e - y e l l o w j a r o s i t e  surfaces, by  and  are  intense  possibly ( u n i t s 3a  sericitization  38  to  reworked from and  3b),  The  fine-grained.  L o c a l l y , however, s u b a n g u l a r  stratiform horizon  from  stratiform  parallels stratigraphy.  wiped out  fragments,  ranging  have a c h a r a c t e r i s t i c a l l y moderate  that  fresh  tuff  vicinity  deposits  foliation  silicification.  lithic  i n the  they d i s p l a y and  ash  o v e r l i e s the 3b)  Northstar  because  units  rocks are  and  f a c i e s of  genesis  Pale grey b a s a l t i c - a n d e s i t e  and  "ore"  s u l f i d e s and  shows t h a t  Hangingwall Volcanic  Unit  tuff  stratiform, volcanogenic mineralization  importance w i l l  3.2.3  the  shard  gangue  numerous.  submarine environment. its  within  T o r b r i t mine.  v e i n l e t s are  Stable unit  the  growths around  can  subrounded the be  recognized. observed  One  l a r g e carbonate  underground a t the  Finely  disseminated  veins,  are  Unit  locally  4,  pyrite,  shards,  preferentially,  comprise  range from  include: pyrite,  less  Four (1)  40  unique  large,  monomineralic,  completely  anhedral  altered  are  denoted  1.0mm  in  f r a g m e n t s were r e c o g n i z e d  and  sericite,  altered  of  (2)  subhedral 30  to s e r i c i t e ,  lithic  fragments  percent (3) of  percent  small, crystal  subhedral  plagioclase.  20  percent  either fragments Plagioclase  to unit  very  fine-grained matrix  sericite  0.1mm  of  first  trains  of  and  and  similar  directions  by  average  unit  polygonal grain boundaries,  of the  The  t o 30mm and  Quartz  the  probably  averaging  section.  of  display  numerous t h r o u g h o u t  Two  most o r i e n t e d  calcite  fragments--primarily Veinlets  10  quartz or  to s e r i c i t e .  recrystallized, Alteration  (4)  developed  percent  of  and  numerous  40  subrounded  o r q u a r t z , and  is  carbonate  a weakly  subrounded aggregates  carbonate  fragments,  either  0.1mm  with  fragments,  between 30  types  percent  vitric  of  ( F i g . 3.19).  quartz or  vitroclastic  supported  than  c e m e n t e d by  calcite  either  p o s s i b l e fiamme', and  Matrix  diameter.  and  was  abundant.  welded t e x t u r e .  and  30cm a c r o s s ,  Northstar deposit  i s predominantly  devitrified  boulder,  with  i n width, unit  lesser  same as  amounts o f  of e i t h e r  the  quartz.  calcite  or  quartz,  have been r e c o g n i z e d  in  thin  4.  foliation  i s c h a r a c t e r i z e d by sericite  i s the  3.  wispy, u n d u l a t i n g  t h a t wrap a r o u n d p y r i t e  39  layers  fragments.  This  i s probably  original the  bedding.  first  feature  This  well developed feature  from  A reset Late  Unit  pressure  shadows  f e a t u r e s and  of unit  4, b a s e d on t h e a n a l y s i s o f  the hangingwall of the Northstar (Table  deposit i s  3.3: s e c t i o n 3.2; F i g s . 3.33 and 3 . 3 4 ) .  C r e t a c e o u s d a t e o f 70.7 _+ 2.5 Ma was a l s o  unit  (Table  obtained  4.3; s e c t i o n 4 . 3 ) .  5  most e x t e n s i v e  and e a s i l y  recognizable  camp b e c a u s e o f i t s d i s t i n c t i v e u n i t i s exposed w e l l  map-area, a s w e l l  this  unit  ( F i g s . 3.1 and 3 . 4 ) .  i s marked by l o c a l  however, maroon t u f f s  horizon (units these  i n the Dolly  Varden  appearance. of the  o f t h e S o u t h M u s k e t e e r and The b a s e and t h e t o p  unconformities  ( F i g . 3.6).  unit 5 i s underlain  ( u n i t 1 ) . In the D o l l y Varden  areas,  unit  ( u n i t 5) i s t h e  i n the southwestern corner  S o u t h o f t h e Moose-Lamb p r o s p e c t , tuff  tuff  c o l o r and f r a g m e n t a l  as i n the areas  Moose-Lamb p r o s p e c t s of  pyrite  the primary  Maroon b a s a l t i c - a n d e s i t e a s h - l a p i l l i  The  reflects  a s t r u c t u r a l event a f t e r d e p o s i t i o n .  basaltic-andesite  from t h i s  sericite  cross-cuts  Chemical c l a s s i f i c a t i o n sample  that  The s e c o n d d i r e c t i o n i s 70 t o 90 d e g r e e s t o  with  3.20).  indicates  one  of f l a t t e n i n g  and i s marked by a l i g n m e n t o f e u h e d r a l  porphyroblasts (Fig.  a primary  overly  by g r e e n  ( E a s t and West) and the m i n e r a l i z e d  Northstar  stratiform  ( u n i t 3) and r e l a t e d f o o t w a l l and h a n g i n g w a l l  tuffs  2b and 4, r e s p e c t i v e l y ) . H a n g i n g w a l l maroon t u f f s i n areas d i s p l a y unique features  40  discussed  below.  I F i g u r e 3.15. M a s s i v e s p h a l e r i t e and p y r i t e w i t h c o a r s e - g r a i n e d bladed b a r i t e c r y s t a l s i n c a r b o n a t e - s u l f a t e - s u l f i d e exhalite ( u n i t 3b). W i d t h o f p h o t o m i c r o g r a p h i s 7.0mm ( p l a n e , r e f l e c t e d light).  F i g u r e 3.16. C o l l o f o r m l a y e r s o f h e m a t i t e a n d m a g n e t i t e i n s u l f a t e - o x i d e - s u l f i d e e x h a l i t e ( u n i t 3 c ) . Width o f p h o t o m i c r o g r a p h i s 7.0mm ( p l a n e , r e f l e c t e d l i g h t ) .  41  F i g u r e 3.17. Well developed l a y e r s of b a r i t e , j a s p e r s u l f i d e s i n s u l f a t e - o x i d e - s u l f i d e e x h a l i t e ( u n i t 3c) underground workings at the T o r b r i t mine.  42  and from  !^ U r V - ! 8 -  SL1 ? ^. un  P  t  SS o  l  i  s  h  e  S U lsf li ad eb d  of  g a l e n a  ° »  and « »  43  j a s p e r  m i n e r a l i z a t i o n  s u l f g t e - o x r ^ s u l r ^ " '  I  F i g u r e 3.19. C a r b o n a t e b o u l d e r , 30cm a c r o s s , i n p a l e g r e y b a s a l t i c - a n d e s i t e a s h t u f f ( u n i t 4) f r o m u n d e r g r o u n d w o r k i n g s a t the N o r t h s t a r d e p o s i t . T h i s boulder i s p o s s i b l y reworked from the u n d e r l y i n g c a r b o n a t e - s u l f a t e - s u l f i d e e x h a l i t e ( u n i t 3b). Hammer i s o r i e n t e d p e r p e n d i c u l a r t o b e d d i n g .  F i g u r e 3.20. S e c o n d a r y f o l i a t i o n i n p a l e g r e y b a s a l t i c - a n d e s i t e a s h t u f f ( u n i t 4 ) . The s e c o n d a r y f o l i a t i o n , o b l i q u e t o pervasive f o l i a t i o n that probably r e f l e c t s o r i g i n a l bedding, i s marked by a l i g n m e n t o f a e u h e d r a l p y r i t e p o r p h y r o b l a s t w i t h a w e l l d e v e l o p e d s e r i c i t e p r e s s u r e shadow. Width o f p h o t o m i c r o g r a p h i s 1.6mm (plane l i g h t ) .  44  Maroon t u f f s Torbrit  df u n i t  Mine a r e a , up  area.  This  unit  highly  resistant  range  i n t h i c k n e s s from  10m  to at least  385m i n t h e D o l l y  Varden  forms  5,  massive,  to weathering.  typically  g r e y - m a r o o n and  Foliation  tends to p a r a l l e l  defined  by  reworked  dominantly various to  display  fresh  of g r e e n .  forming outcrops that  widely spaced,  observed  locally  Fragments, 0.1mm  surfaces,  fragments percent  bombs, up  and  average  (locally  sericite,  oriented  up  75  percent of u n i t  and 30  t o 70  consist  q u a r t z and  pyroxene  The  crystals  percent),  fine  have  been  of  50  Rare  welded  of r e l i c t  have been a l t e r e d and  h a n g i n g w a l l maroon t u f f s  45  from  percent lithic  15 p e r c e n t h e m a t i t e  grains.  chlorite  range  They a r e m a t r i x  matrix.  5  This  feldspars  to  and  flattened,  t r a c e s o f c a r b o n a t e and  i s p s e u d o m o r p h e d by  unique  5,  p e r c e n t maroon t u f f  m a t r i x i s an a g g r e g a t e  Most p l a g i o c l a s e  shows  crystals.  t o 50cm i n d i a m e t e r ,  s u b h e d r a l pyroxene  minor  5 is  the r o c k s are  plagioclase  fiamme'-like s h a r d s o c c u r i n a p o s s i b l y fine-grained  Unit  but o c c a s s i o n a l l y  2.0mm a c r o s s .  (An23 t o A n 3 2 ) ,  broken,  joints.  commonly  r e d ash t u f f .  I n hand s p e c i m e n ,  between 25  randomly  plagioclase  are  ( F i g . 3.21).  t o 20.0mm and  supported,  regular  bedding, with bedding  medium g r a i n e d w i t h a b u n d a n t b r o k e n  S u b r o u n d e d , maroon t u f f  West  Weathered s u r f a c e s are  lenses of b r i c k  maroon on  shades  cliff  i n the  and  chlorite.  sericite;  iron oxides.  of u n i t  5,  noted  above,  near  the  Dolly  f o r m e d as unit  Varden  ( E a s t and  a pyroclastic  West) and  f l o w of  limited  tends  t o be  less  lack green  color  when compared t o t h e  are  finer  shards less  g r a i n e d and  seen  than  1mm  shards  lithic  fragments,  10  (unit  from  dust.  The  and  matrix  25  occurs  as  3.4),  (Figs.  lithic  c o a t i n g s on  shards  analysis  an  and and  from  of  50  percent  2b),  10  and  3.34).  A reset  quartz,  hematite  either  sericite.  grains.  section  lesser hematite  carbonate, to  carbonate also  crystals.  3.3)  (Figs.  ore  layer  Hematite  plagioclase  o f one (Figs.  3.33  sample 3.1  and  and  3.34),  maroon t u f f s  i n the  showed a b a s a l t i c Late Cretaceous  46  percent  r e p r e s e n t reworked  Moose-Lamb d e p o s i t  Moose-Lamb a r e a s ,  unit.  vitroclastic.  f e l d s p a r s and  the h a n g i n g w a l l  green  averaging  fragments have a l t e r e d  andesite composition  samples  and  3.33  Fragments  of t h i s  carbonate,  relict  ( T a b l e 3.3:  5 u n d e r l y i n g the  yielded  Northstar  sparse  hematite  whereas two  5.  5 percent  anhedral  f r a g m e n t s may  chlorite,  Chemical unit  plagioclase,  g e n e r a l l y r e p l a c e d by  or c h l o r i t e ;  lesser  percent  in footwall unit  percent  specimens  veins,  consist  i s d o m i n a t e d by  q u a r t z , and  Shards are  sericite  from  and  hand  the u n d e r l y i n g c a r b o n a t e - r i c h s t r a t i f o r m  3b).  sericite  and  to those  This  numerous d a r k  are dominantly  i n l e n g t h and  subrounded carbonate  clasts  t o 10  section  percent  t r a c e s of hornblende Rare,  o c c u p y up  and  of u n i t  Calcite  1.0mm  (similar  rest  ( F i g . 3.22).  in thin  extent.  to weathering  with  i n width,  Fragments average  aerial  more a n g u l a r ,  i n places  T h e s e maroon t u f f s  platy  resistant  Northstar deposits,  composition  date  of  68.1  +  2.5 Ma was o b t a i n e d mentioned above, (Table  by K-Ar a n a l y s i s o f t h e same  from  sample,  t h e f o o t w a l l o f t h e Moose-Lamb d e p o s i t  4.3: s e c t i o n 4 . 3 ) .  Unit 6 Tuffaceous central  rocks  of u n i t  6 a r e most w i d e s p r e a d  p a r t o f t h e map-area, n e a r t h e N o r t h s t a r  deposits,  and t h e S o u t h M u s k e t e e r  This  i s subdivided  unit  prospect  i n t o dark grey  w h i c h g r a d e s upwards and l a t e r a l l y green tuff  tuff (unit  recognized  (unit  6b).  Units  i n the hangingwall  3.1  tuff  t o the northeast  6a and 6b o v e r l i e  2b) a n d maroon t u f f  and T o r b r i t  (Figs.  lapilli  i n the  (unit  both  and 3 . 4 ) .  (unit into  6a) dark  green  shard  5 ) , and have a l s o been  of the N o r t h s t a r  and T o r b r i t  deposits.  Dark g r e y aerial small with  extent  andesite  regular joint  Fresh  (unit  6a) has a  Weathered  limited  Outcrops are  s u r f a c e s a r e smooth a n d g r e y ,  p a t t e r n s , crudely developed  foliation  and a  t e x t u r e where b r e c c i a f r a g m e n t s h a v e w e a t h e r e d o u t . s u r f a c e s show an a p h a n i t i c , d a r k g r e y  numerous l i g h t lapilli  sized  green,  0.1  poorly  fragments  Fragments average from  tuff  and a maximum t h i c k n e s s o f 165m.  and s p o r a d i c .  pitted  lapilli  sorted, angular  up t o 5cm a c r o s s  45 p e r c e n t  of the rock  r a n d o m l y o r i e n t e d , and c o n s i s t  47  to  hosting  subangular,  ( F i g . 3.23).  t o 10.0mm and a v e r a g e 2.0mm a c r o s s .  supported,  matrix  and g e n e r a l l y r a n g e They a r e m a t r i x  o f 65 p e r c e n t  lithic  F i g u r e 3.21. S u b r o u n d e d t o s u b a n g u l a r maroon t u f f l i t h i c f r a g m e n t s , up t o 50cm a c r o s s , i n maroon b a s a l t i c - a n r l p g i a s h - l a p i l l i tuff (unit 5). " t  48  e  I  Figure 3.22. P l a t y shards i n a l o c a l p y r o c l a s t i c flow w i t h i n maroon b a s a l t i c - a n d e s i t e a s h - l a p i l l i t u f f ( u n i t 5 ) . Opaques a r e p r i m a r i l y h e m a t i t e , w h i c h o c c u r s as b o t h a n h e d r a l g r a i n s and c o a t i n g s on s h a r d s . W i d t h o f p h o t o m i c r o g r a p h i s 4.2mm ( p l a n e light) .  49  fragments, biotite  25 p e r c e n t  subhedral  and 2 p e r c e n t  fine-grained  iron  oxides.  to carbonate  cleavage.  Lithic  carbonate  a maximum  generally  unit.  (unit  than  i s fine  lithic  and c o n s i s t  by  Musketeer  and reaches area. This  rock,  t o medium g r a i n e d a n d h a s  Finely  clasts  and m i n o r  disseminated  pyrite i s  1 percent.  i n unit  range from  chloritized  that follow basal  6b) i s w i d e s p r e a d  and v i t r i c  fragments.  6b c o m p r i s e  less  than  between 40 and 60 p e r c e n t o f  matrix  supported,  randomly  0.1 t o 10.0mm and a v e r a g e  o f 45 p e r c e n t  85 p e r c e n t ) , 40 p e r c e n t  pyrite.  oxides  has b e e n  and s e r i c i t e .  They a r e s u b a n g u l a r ,  oriented,  and  green  less  biotite  g r e y - b r o w n and c r u d e l y f o l i a t e d .  crystal  Fragments  to  andesite tuff  when f r e s h ,  plagioclase  i s very  f r a g m e n t s h a v e been r e p l a c e d c o m p l e t e l y  are light  abundant d a r k  across,  of i r o n  t h i c k n e s s o f 225m i n t h e N o r t h  grey-green  the  ribs  matrix  8 percent  Plagioclase crystals  and c h l o r i t e ;  w i t h minor c h l o r i t e  Dark g r e e n  Outcrops  with  crystals,  The g r e e n  a n d d o m i n a t e d by c h l o r i t e .  a r e p s e u d o m o r p h e d by s e r i c i t e altered  plagioclase  lithic  plagioclase  fragments  fragments,  1.0mm  (locally 10 p e r c e n t  shards,  and 5 p e r c e n t  opaques, t h a t a r e mainly  The m a t r i x  i s dominantly  chlorite,  carbonate,  Underground stratiform  and s p a r s e  with  up  lesser  sericite  quartz.  a t the T o r b r i t  mineralization (unit  mine, u n i t  6b d i r e c t l y  3c) and c o n t a i n s  50  overlies  subrounded  fragments both  of the underlying ore.  These o r e fragments  m a s s i v e and l a y e r e d o r e t y p e s ,  quartz,  lesser  carbonate  Coarse-grained, identified  The based  i n many  chemical  principally  bladed  barite  (Figs.  24 and 2 5 ) .  and/or w i t h e r i t e ,  was  fragments.  composition  on a n a l y s e s  and c o n t a i n b a r i t e and  and t r a c e s o f j a s p e r  subhedral,  represent  of unit  o f one sample  andesitic  (Figs.  from  6 ( T a b l e 3.3: s e c t i o n 3 . 3 ) , each of u n i t s  6a a n d 6b, i s  3.33 a n d 3 . 3 4 ) .  Unit 7 Subvolcanic 7a),  together  (unit  with  7b), occur  southwestern  reaches  showing  or flows  of p o r p h y r i t i c  a pyroclastic  throughout  porphyritic  andesite  (Figs.  3.1 a n d 3 . 4 ) .  (unit  7a) c o v e r s  o f n e a r l y 1km, n e a r  3.1 a n d 3 . 4 ) .  Dimensional  w i t h i n t h e map-area a r e n o t w e l l known.  pale  grey-brown outcrops  either  steep  Limonite  cliffs  pale grey  or white.  a f i n e - g r a i n e d matrix with phenocrysts  hornblende,  and t r a c e p y r o x e n e .  silicification  imparts  with  unit  Combination i n this  these  rocks  they are  7a i s g r e y - g r e e n ,  of p l a g i o c l a s e ,  Sericitization  and/or  a m a s s i v e a p p e a r a n c e t o some o f t h e s e  51  area  blocky,  locally  When f r e s h ,  a vast  Characteristically  pervasively stains  an o r a n g e - b r o w n o r o r a n g e - y e l l o w ;  bleached has  fractures.  form  the  variations  unit  irregular  (unit  most o f t h e n o r t h e r n a n d  a maximum w i d t h  (Figs.  andesite  equivalent of andesite ash t u f f  p a r t s o f t h e map-area  Grey-green and  sills  rocks. are  Finely  associated  pyritization (unit  disseminated pyrite closely  (unit  with  7a(s)),  zones and  is ubiquitous.  U n i t 7a  of s e r i c i t i z a t i o n  silicification  7a(q)), discussed i n d e t a i l  later  and  in this  rocks  and  pyritization  chapter  (section  3.5).  Unit  7a,  in thin  section,  i s similar  i n texture  mineralogy  t o t h e g r e e n _+ maroon p o r p h y r i t i c  2a,  i t lacks  except  26). 35  Subhedral,  and  55  average of  hornblende percent  65  1.0mm  range  The  from  up  t o 45  Phenocrysts  gone t o c h l o r i t e  and  o p a q u e s , and  i s u n o r i e n t e d and  q u a r t z and  sparse  Pale green from  50m  area  (Figs.  sericite,  a n d e s i t e ash  i n the North 3.1  for local  and  chlorite dominated carbonate  tuff  Musketeer  3.4).  (unit  0.1  20  Outcrops  pyroxene The  by  chlorite,  and  feldspar.  7b)  ranges  t o 52 5m  and  52  has  fine-grained lesser  Wolf  This unit  indistinct  have  structureless,  on  w i t h an  10  i n thickness  g r e y - b r o w n where w e a t h e r e d , p a l e massive  and  is  i n the  are g e n e r a l l y fracturing.  to  percent  hornblende  locally.  a r e a , up  blocky, irregular  surfaces,  than  assemblage  characteristically fresh  between  of p l a g i o c l a s e  minor c h l o r i t e ,  groundmass  less  (An25),  and  and  comprise  p e r c e n t ) , 5 p e r c e n t pyroxene  pyrite.  calcite  unit  textures (Fig.  phenocryst  to s e r i c i t e  p s e u d o m o r p h e d by  except  phenocrysts  and  across.  opaques, mainly  partially  unit,  a n d e s i t e of  amygdaloidal  p e r c e n t unzoned p l a g i o c l a s e  (locally  a l t e r e d mainly  and  randomly o r i e n t e d  percent of t h i s  5.0mm and consists  trachytic  and  is  grey-green  tuffaceous  texture, green,  w h i c h on  light  careful  green  and  i n s p e c t i o n of  r e d fragments  sawn s l a b s r e v e a l s  generally less  than  dark 1mm  across.  Unit  7b,  subangular directed  as v i e w e d  and  matrix  in thin  section,  supported;  ( F i g . 3.27).  An  has  fabrics  epiclastic  are both  component  numerous s u b r o u n d e d g r a i n s o f q u a r t z  and  Fragments comprise  percent  b e t w e e n 20  range from  less  diameter.  They c o n s i s t  crystals iron  (An20),  oxides,  lapilli  than  10  of the  30  0.1  of  same a s h  50  because of  carbonate  occurs  radiating  aggregates  quartz,  tuff  lithic  material.  i s d o m i n a t e d by  by  and  0.3mm i n  percent  although  sericite  and  Sericite  identified  7  rounded  matrix,  pseudomorphs and  o f p r e h n i t e was  unit,  biotite,  i t s high birefringence.  in plagioclase  and  fragments.  t r a c e s of The  are  plagioclase  3 percent and  random  of t h i s  broken  that  is identified  average  percent  g l a s s shards  probably  carbonate  40  10.0mm and  percent  percent  cryptocrystalline,  to  and  fragments  and  interstitial, i n some  specimens.  The Figs.  chemical  3.33  and  composition  3.34)  of u n i t  is principally  7  ( T a b l e 3.3:  a n d e s i t e , based  analysis  of  two  samples  from  unit  7a and  7b.  of  the  samples  from  unit  7a,  and  One  indicated  composition (unit  a basaltic-andesite  of host  7 b ) , was  rocks  confirmed  one  sample  however, was  composition.  section on  Thiersch  53  (1986).  the  from  unit  altered  less  Andesitic  t o m i n e r a l i z a t i o n i n t h e Wolf by  3.3;  area  F i g u r e 3.23. L i g h t g r e e n , a n g u l a r t o s u b a n g u l a r , l a p i l l i - s i z e d l i t h i c f r a g m e n t s , up t o 5cm a c r o s s , i n d a r k g r e y a n d e s i t e l a p i l l i t u f f ( u n i t 6 a ) . The f r a g m e n t s have b e e n c o m p l e t e l y a l t e r e d t o c a r b o n a t e and c h l o r i t e .  54  I F i g u r e 3.24. Hand s p e c i m e n o f d a r k g r e e n a n d e s i t e t u f f ( u n i t 6b) t h a t c o n t a i n s an o r e f r a g m e n t f r o m t h e u n d e r l y i n g s u l f a t e - o x i d e - s u l f i d e e x h a l i t e ( u n i t 3 c ) . The o r e f r a g m e n t i n t h i s s p e c i m e n , t a k e n from u n d e r g r o u n d w o r k i n g s a t t h e T o r b r i t mine, c o n t a i n s l a y e r s o f q u a r t z , c a r b o n a t e , b a r i t e and j a s p e r .  F i g u r e 3.25. T h i n s e c t i o n o f d a r k g r e e n a n d e s i t e t u f f ( u n i t 6b) t h a t c o n t a i n s f r a g m e n t s o f c a r b o n a t e and b a r i t e o r e f r o m t h e s u l f a t e - o x i d e - s u l f i d e e x h a l i t e ( u n i t 3 c ) . The m a t r i x i s dominantly c h l o r i t e . W i d t h o f p h o t o m i c r o g r a p h i s 4.6mm (polarized l i g h t ) .  55  1 F i g u r e 3.26. P h e n o c r y s t s o f p l a g i o c l a s e a n d h o r n b l e n d e i n grey-green p o r p h y r i t i c andesite (unit 7a). Width o f p h o t o m i c r o g r a p h i s 4.6mm ( p o l a r i z e d l i g h t ) .  F i g u r e 3.27. P l a g i o c l a s e c r y s t a l f r a g m e n t s , and s u b r o u n d e d g r a i n s o f q u a r t z and l i t h i c fragments, i n p a l e g r e e n a n d e s i t e ash t u f f ( u n i t 7 b ) . The m a t r i x i s f i n e - g r a i n e d t u f f a c e o u s m a t e r i a l t h a t has been a l t e r e d t o s e r i c i t e and c a r b o n a t e . Width of p h o t o m i c r o g r a p h i s 4.6mm ( p o l a r i z e d l i g h t ) .  56  Lead unit et  isotope  analysis  7a s u g g e s t s  a l . , 1987).  that This  probably J u r a s s i c from t h e D o l l y later  indicates  that  8 exposed  the  K i t s a u l t River  in detail  data  in a  local  unconformity  volcanic (unit  rocks.  group  i n the D o l l y  separates  these rocks  They c o n s i s t  8a), overlain which  parts  overly  Moose-Lamb p r o s p e c t s sporadic,  spaced,  characteristic. The u n i t  V a r d e n camp b e c a u s e a from  the  s i l t s t o n e and s h a l e  underlying  3.1 and 3 . 4 ) .  Fresh  surfaces  i s mainly  Outcrops of t h i s  57  maroon.  unit  Closely  bedding are a l s o  are t y p i c a l l y  fine-grained  (unit 8 c ) .  7b n e a r t h e Wolf and  w e a t h e r e d and l i g h t  j o i n t s and d i s t i n c t  (unit  o f d i s c o n t i n u o u s b e d s up  ash t u f f s of u n i t  (Figs.  recessively  subparallel  are the youngest  o f a l o w e r m o s t maroon s i l t s t o n e  Maroon s i l t s t o n e ( u n i t 8a) c o n s i s t s that  o f t h e map-area, and i n  by c a l c a r e o u s and f o s s i l i f e r o u s wacke  i s c a p p e d by b l a c k  90m t h i c k  ( F i g s . 3.1 a n d 3.4) i n  v a l l e y t o the northwest,  rocks of the Hazelton  red.  isotope  8  s o u t h e a s t e r n and n o r t h e a s t e r n  are  of lead  7a i s  Rocks  the  to  (cf. Alldrick  t h e age o f u n i t  be d i s c u s s e d  cutting  ( s e c t i o n 4.4).  Sedimentary rocks of u n i t  8b),  i s Jurassic  Interpretation  V a r d e n camp w i l l  chapter  from a q u a r t z v e i n  mineralization  or older.  3.2.4 S e d i m e n t a r y  Unit  of galena  maroon t o b r i c k  and m a s s i v e , w i t h  local  i n t e r b e d s of conglomerate rounded, places,  grey this  and w h i t e unit  with d i s t i n c t i v e  clasts,  up t o 2cm  contains jasper,  but minor,  local,  i n diameter.  I n some  which d i s p l a y s c o n c h o i d a l  fractures.  Thin abundant  section  examination  subangular  of u n i t  fragments  8a shows b e d d i n g ;  suggests  that  pyroclastic-epiclastic  rock or t u f f i t e  and  Fragments comprise  Schmincke,  unit  and r a n g e  1984). from  less  diameter.  They c o n s i s t  indistinct  feldspar  completely  altered  hematite,  than  sorted  minor c a r b o n a t e  to s e r i c i t e  and t r a c e s  and s e t i n an a l t e r e d  wacke  green  ash t u f f  near  t h e Moose-Lamb,  unit  regularly fossil Fresh  (unit North  Outcrops  a r e abundant  in  b u t a r e now  of b i o t i t e .  They a r e  matrix of s e r i c i t e  fractured that  (unit  thick  with  8b) c o n s i s t s o f  that  overlies  7b) o r maroon s i l t s t o n e Musketeer  generally  well  weather grey except limonite  (Figs.  where stained.  b e d d e d , c r u d e l y f o l i a t e d and  ( F i g . 28).  C e r t a i n b e d s o f wacke c o n t a i n  i s most r e c o g n i z a b l e on w e a t h e r e d  s u r f a c e s are dark grey,  either  (unit 8a),  and Wolf p r o s p e c t s  they are orange-yellow  i s moderately  material  0.1mm  and q u a r t z .  pale  This  40 p e r c e n t o f t h i s  and c a r b o n a t e ) , 20 p e r c e n t  c o n t i n u o u s b e d s up t o 80m  sulfides  i n Fisher  t o 0.5mm and a v e r a g e  relatively  and 3 . 4 ) .  1981  grains (probably p l a g i o c l a s e  C a l c a r e o u s and f o s s i l i f e r o u s  3.1  (Schmid,  8a i s a m i x e d  o f 45 p e r c e n t q u a r t z , 30 p e r c e n t  5 percent muscovite  moderately  0.1  unit  and  fine-grained  58  surfaces.  and c a l c a r e o u s .  F i g u r e 3 . 2 8 . W e l l d e v e l o p e d b e d d i n g i n c a l c a r e o u s and f o s s i l i f e r o u s wacke ( u n i t 8 b ) . This outcrop is situated beside t h e K i t s a u l t R i v e r , n e a r t h e K i t s o l s h o w i n g ( F i g s . 3.1 and 3 . 4 ) , and c o n t a i n s numerous b e l e m n o i d , r h y c h o n e l l i d b r a c h i o p o d and pelecypod f o s s i l s .  59  Pyrite  and t r a c e s o f s p h a l e r i t e  fine-grained  Showings o f g a l e n a  were d i s c o v e r e d a p p r o x i m a t e l y  sections of unit  fragments  400m d u e s o u t h o f t h e  supported  and both  They range  0.5mm a c r o s s .  plagioclase  percent  calcite  fragments,  from  and are  i n u n i t 8b Wolf  biotite  less  than  consists  10 p e r c e n t  7a) i s t h e most l i k e l y  porphyry  rock  sericite  and carbonate  fragments  ( F i g . 3.29). w i t h minor  collected  northwestern  The f a u n a  British  communication,  1986)  pelecypods.  porphyry  (primarily  pyrite), 3  and sphene.  Porphyritic  source o f the f e l d s p a r The m a t r i x  from  unit  i s d o m i n a t e d by  8b were s u b m i t t e d t o  o f Canada, V a n c o u v e r , f o r  were s i m i l a r  Columbia  20 p e r c e n t q u a r t z , 10  carbonate.  H.W. T i p p e r o f t h e G e o l o g i c a l S u r v e y identification.  feldspar  q u a r t z ; a n d most o f t h e  h a v e been r e p l a c e d by i r o n  of fossils  o f 50 p e r c e n t  feldspar  and t r a c e s o f muscovite  (unit  A suite  0.1 t o 3.5mm a n d a v e r a g e  s c a t t e r e d opaques  andesite  Fragments  subrounded t o subangular,  and a l l s e r i c i t i z e d ) ,  fragments,  7 percent  matrix.  randomly and p r e f e r e n t i a l l y  Their composition  (mainly  various  planes  8b show a b u n d a n t p o o r l y s o r t e d  60 p e r c e n t o f t h e u n i t  oriented.  fossils  and s p h a l e r i t e  i n a c a l c a r e o u s and arenaceous  fragment  percent  bedding  ( F i g . 3.1).  Thin  average  e i t h e r as  disseminations or concentrated along  i n m i n o r amounts.  prospect  and g a l e n a o c c u r  t o others i n  and i n c l u d e d ( T i p p e r , w r i t t e n  belemnites, Pelecypods  r h y n c h o n e l l i d brachiopods and were i d e n t i f i e d  60  a s Chlamys s p .  and  a fragment  of a coarse  Unfortunately, unit,  the fauna  and  Other  fossil  i n the K i t s a u l t  D. A l l d r i c k ,  p o s s i b l y Weyla spp.  d i d not give a d e f i n i t e  but according t o Tipper  T o a r c i a n age. rocks  ribbed variety,  i t i s probably  suites  River area  collected  age t o t h i s  of Early from  Jurassic,  Hazelton  (Hanson, 1921; C a m p b e l l ,  p e r s . comm., 1986) a l s o  f a v o r an E a r l y  Group 1959;  Jurassic  age.  Black thickness  siltstone  (unit  and t h e t o p o f t h e u n i t  map-area.  U n i t 8c o v e r l i e s  rocks of unit but  and s h a l e  both  regular, black,  closely  spaced  the p o r p h y r i t i c  Fresh  f i n e - g r a i n e d and l a m i n a t e d . interbeds occur  have a l s o  been r e c o g n i z e d .  millimeters  t o tens  8b.  Outcrops  locally.  Light  Beds v a r y  i n thickness  of meters, but average concentrates  with  G r a d e d and c r o s s - b e d d i n g  along  about  when p r e s e n t  i n g r e a t amounts, t h e r o c k s d i s p l a y  from  5cm.  some b e d d i n g  p l a n e s , and  a red-brown  stain.  Black  siltstones  subangular,  and s h a l e s o f u n i t  8c c o n s i s t  randomly o r i e n t e d g r a i n s r a n g i n g  1.0mm  and a v e r a g i n g  occur  in a dirty  percent  are recessive  g r e y mudstone and  pyrite  of  and t u f f a c e o u s  surfaces are generally  Fine-grained  limonite  i n the  w e l l b e d d e d and f o l i a t e d  joints.  sandstone  indefinite  i s not exposed  7 and wackes o f u n i t  when e x p o s e d a r e t y p i c a l l y  8 c ) h a s ah  sericite  0.2mm a c r o s s .  matrix,  altered  25 p e r c e n t  feldspar,  61  from  L o c a l fragments  cryptocrystalline  predominantly 0.1 t o  i n siltstone  consisting quartz,  o f 65 3 percent  biotite  and 7 p e r c e n t g r a i n s o f carbonaceous  hematite. than  Grey  siltstone  beds a r e f i n e r  0.1mm) a n d h a v e a s i m i l a r  carbonaceous  material,  3.2.5 I n t r u s i v e  and minor  grained (generally  mineralogy,  hematite  material  except  less  f o r less  and b i o t i t e .  Rocks  Unit 9 Basalt in,  and lamprophyre  and a r e d i s t r i b u t e d  3.4).  The dykes e r o d e  where t h e y c r o p o u t . granular, chilled  specimen,  and  amygdaloidal.  Thin consist  pyroxene  section  sections  (Figs.  form  developed dykes,  3.1  small  and  gullies with  Columnar j o i n t i n g and  i nplaces.  These dykes  ranging i nwidth  10m, b u t a v e r a g e  about  textures including  i nporphyritic  and z e o l i t e  from  occur  a few  1m ( F i g . 3 . 3 1 ) . fine-grained  massive,  and minor p l a g i o c l a s e . calcite  units  porphyritic  varieties  include:  Amygdules a r e  (probably  analcite  examination).  of unit  of acicular  interstitial euhedral  and t y p i c a l l y  Phenocrysts  with c h l o r i t e ,  thin  t h e map-area  dyke r o c k s a r e d a r k g r e y - g r e e n ,  with variable  hornblende,  9) c u t a l l o t h e r  Weathered s u r f a c e s are^grey-brown  t o more t h a n  soft,  from  easily  are well  and  filled  throughout  swarms o r s i n g l e  centimeters I n hand  (unit  sand-like surface textures.  margins  as e i t h e r  dykes  laths  chlorite  9 ( F i g . 3.30) show t h e groundmass t o of plagioclase  and c a l c i t e .  and randomly o r i e n t e d ;  and pyroxene  Phenocrysts  they range  62  from  with  are subhedral t o 0.1 t o 3.0mm a n d  average from  0.5mm i n s i z e .  20 t o 80 p e r c e n t  typically zoning,  consists  among d y k e s .  o f 50 p e r c e n t  30 p e r c e n t  magnetite  The p r o p o r t i o n o f p h e n o c r y s t s  hornblende,  The p h e n o c r y s t  plagioclase  15 p e r c e n t  and t r a c e s o f a p a t i t e .  assemblage  (An67) w i t h  i n p l a c e s , w h e r e a s most  phenocrysts  h a v e gone  of the hornblende iron  minor  augite, 5 percent  P l a g i o c l a s e has b e e n  to c h l o r i t e  to chlorite,  varies  oxides  altered and a u g i t e  and, l o c a l l y ,  carbonate.  The c o m p o s i t i o n crosscutting Northstar  ( T a b l e 3.3: s e c t i o n  stratiform  deposit  4.3:  section  mineralization (unit  ( F i g . 3 . 1 ) , was b a s a l t  A w h o l e r o c k K-Ar d a t e  3.3) o f a d y k e 3b) a t t h e  (Figs.  3.33 and 3 . 3 4 ) .  o f 22.3 +_ 0.8 Ma f o r t h e same d y k e  4.3) i n d i c a t e s  emplacement  63  d u r i n g Miocene  (Table  time.  I  F i g u r e 3.29 C o a r s e - g r a i n e d , p o o r l y s o r t e d f r a g m e n t s i n c a l c a r e o u s a n d f o s s i l i f e r o u s wacke ( u n i t 8 b ) . Note t h e l a r g e f e l d s p a r porphyry rock fragment. Width o f photomicrograph i s 4.6mm ( p o l a r i z e d l i g h t ) .  I  F i g u r e 3.30. B a s a l t dyke ( u n i t 9) composed o f l a t h s o f a u g i t e i n a p l a g i o c l a s e d o m i n a t e d groundmass. Width of photomicrograph i s 2.2mm ( p o l a r i z e d l i g h t ) .  64  F i g u r e 3 . 3 1 . B a s a l t d y k e ( u n i t 9) c r o s s c u t t i n g g r e e n + / - maroon b a s a l t i c - a n d e s i t e t u f f ( u n i t 1) on a r o a d c u t n e a r t h e T o r b r i t mine. Note c o l u m n a r j o i n t i n g p e r p e n d i c u l a r t o w a l l s o f d y k e .  65  3.3  CHEMISTRY OF IGNEOUS ROCKS  Chemical from  analyses  of s e l e c t e d , r e p r e s e n t a t i v e igneous  t h e D o l l y V a r d e n camp  Hazelton  Group v o l c a n i c r o c k s  calc-alkaline plots  ( F i g . 3.1) a r e i n T a b l e  field  rocks are a l s o intermediate the  are subalkaline, displaying  ( F i g . 3.32).  i n composition  predominance o f a n d e s i t i c  and a v e r a g i n g  basic  Gill  andesites after  andesites. of  by h a v i n g percent.  percent  i s too high  either  f o r Ti02,  f o r orogenic  andesites are probably  Andesites,  potassium  percent  calc-alkaline  "orogenic"  Si02,  Si02.  Si02,  types  - 5.135) and T i 0 2 <  i n the D o l l y Varden  andesite. Nonetheless, h i g h K20 v a l u e s  camp  the  might  either  alteration.  (1981), a r e  v o l c a n i c rocks with calculated  between 53 a n d 63  on a n a n h y d r o u s b a s i s .  s u b d i v i d e s them i n t o b a s i c a n d e s i t e s , w i t h  weight percent percent  Si02, are  also established  metasomatism accompanying  a s d e f i n e d by G i l l  hypersthene-normative  further  a n d c h a r a c t e r i z e d by  b u t a K20 a v e r a g e o f 5  orogenic—the  metamorphism o r h y d r o t h e r m a l  weight  of t y p i c a l  Volcanic rocks  the requirements  1.  Gill  K20 < (0.145 x S i 0 2  satisfy  reflect  Group  These a r e d i s t i n g u i s h e d c h e m i c a l l y from o t h e r  andesites  1.75 w e i g h t  dyke  The H a z e l t o n  55 w e i g h t p e r c e n t  (1981)1.  for classification  a  v o l c a n i c s . D o l l y Varden v o l c a n i c s ,  hypersthene-normative  criteria  3.3.  t r e n d on an AFM d i a g r a m , and t h e T e r t i a r y  i n the t h o l e i i t i c  rocks  and a c i d  andesites with  He  53 t o 57  57 t o 63 w e i g h t  TABLE 3 . 3 . Whole rock chemistry (XRF)1 and norma t i y e c a l c u l a t i o n s ^ for igneous rocks from the D o l l y Warden camp, northwestern B . C . 3.1.  Sample l o c a t i o n s are p l o t t e d on f i g u r e  Data are p l o t t e d i n Figures 3.32 to 3.34.  Unit  2a  2b  2b  2b  5  6a  7a  7a  T177  T37a  0227  0376  T123  0U84-NS1  035  0335  D364a  085  0382b  030ft  T263  D32  G19  S102  50.93  53.16  54.19  55.77  60.04  52.55  60.24  51.78  51.52  57.76  61 .88  46.13  54.40  61 .22  41.25  U02  0.74  0.66  0.79  0.59  0.72  0.69  0.60  0.68  0.62  0.56  0.53  0.71  0.52  0.85  17.06  17.60  18.93  17.91  16.73  16.35  16.14  16.05  15.28  15.16  16.40  15.51  16.80  15.0B  Sample number  1  5  U  5  6b  7b  9  Major Elements (weight percent)  A1203  1E.06  3.02  Fe2Q33  8.49  6.75  8.09  6.52  6.94  6.52  5.40  7.54  6.90  4.43  3.01  11.24  6.18  6.24  12.10  PlnO  0.25  0.09  0.28  0.37  0.09  0.11  0.15  0.19  0.29  0.15  0.21  0.27  0.20  0.11  0.2B  PlgO  2.55  2.45  1.98  1.48  2.53  1.46  1.43  1.97  2.69  1.49  0.76  7.14  1.41  3.62  4.99  CaO  3.69  3.04  2.44  D.B7  1.30  1.48  3.41  6.01  6.90  6.62  1.21  6.33  3.03  2.22  10.38  Na20  0.B4  1.82  0.09  0.15  0.92  0.15  2.39  0.30  1.32  1.56  0.16  1 .64  0.45  0.88  1 .91  K20  5.40  3.94  5.30  10.70  3.70  4.57  4.34  4.12  6.08  2.66  8.61  2.59  6.46  3.30  0.78  0.52 0.66  0.44  0.48  0.50  0.48  0.57  0.92  0.34  0.17  2.25  0.00  0.00  0.01  0.00  0.00  0.04  0.27  0.0  0.01  •  P20S  0.66  0.53  0.55  0.62  0.32  S  0.00  0.00  0.00  0.02  0.00  LDH Totals  5.62  4.98  5.53  2.75  4.26  6.89  3.53  B.32  7.02  6.71  2.61  3.15  2.74  4.34  6.23  96.23  95.04  98.17  97.75  97.55  96.97  98.07  97.44  99.13  98.50  94.71  96.56  91.51  99.75  9B.2B  1828.68  486.54  Trace Elements (ppm) 2571.44  1203.50  2559.39  1507.19  3391.86  3213.42  3313.38  2843.99  1089.21  4516.72  922.96  3557.B4  1518.60  Co  Ba  21.3B  19.39  9.55  14.75  17.23  17.67  15.83  12.78  15.93  15.63  4.20  27.83  14.96  16.54  30.70  Cr  39.73  40.27  16.75  39.82  31.83  52.14  62.16  51.68  18.51  30.93  30.48  82.95  44.76  32.78  69.01  Cu  16.90  23.49  15.04  9.34  11.52  32.56  26.04  7.17  20.19  14.46  6.64  95.84  16.42  25.20  33.30  Kb  3.92  5.91  4.63  7.03  7.01  5.32  5.94  5.05  5.34  5.31  5.54  4.48  5.87  11 .36  18.44  Ni  10.17  8.50  3.48  7.58  B.76  7.63  5.65  3.16  7.61  5.43  5.07  18.92  7.94  10.24  30.B2  Pb  21.65  16.61  11.40  54.78  3.16  166.22  20.68  10.06  17.76  20.53  29.40  6.09  21 .52  15.20  10. B6  Rb  181 .97  120.49  150.16  272.73  128.10  185.08  121.62  142.01  150.47  70.97  205.41  52.97  176.89  103.24  8.31  Sr  95.04  388.81  88.27  96.61  89.99  61 .17  862.90  216.05  261.60  557.49  85.30  647.53  168.70  465.83  755.88  V  141 .10  131.40  168.68  107.23  128.49  145.09  104.48  154.41  124.0B  126.38  120.36  205.60  116.71  92.94  227.53  Y  17.24  15.42  19.14  20.31  15.46  16.80  17.64  17.15  17.37  14.01  18.39  15.56  18.60  35 .S1  26.18  Zn  242.56  105.37  434.96  293.42  93.B6  390.00  126.90  78.15  137.95  97.87  135.20  216.81  81 .93  111 .96  111.73  Zr  71.21  130.29  81 .03  105.72  105.81  74.84  133.94  77.06  85.86  112.87  92.39  71.05  102.75  172.6B  201 .82  Normative Minerals (weight percent) Quartz  11.49  16.26  23.12  8.86  32.23  24.71  19.89  16.50  3.06  22.74  25.88  0.00  17.IB  31 .98  2.64  Orthoclase  31.91  23.28  31.32  63.23  21.86  27.01  25.65  24.35  35.93  15.72  50. BB  15.30  38.17  19.50  4.61  7.11  15.40  0.76  1.27  7.78  1 .27  20.22  2.54  11.17  13.20  1.35  13.88  3.81  7.45  16.16  13.99  11.62  8.51  0.27  4.36  3.94  14.04  26.68  17.81  28.96  2.2B  25.39  12.81  9.90  30.27  Albite Arorthite Diopside Hyperstnene  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  10.B7  0.60  0.00  15.22  11.74  12.91  9.77  12.11  15.92  7.17  12.18  7.84  5.34  1 .69  0.00  0.00  0.00  5.27  26.90  8.44  13.02  15.58  Olivine  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  3.58  0.00  0.00  0.00  Caruidun  4.70  6.08  9.93  5.98  9.61  9.71  2.36  1 .32  0.00  0.00  4.74  1.59  3.08  B.15  0.00  Apatite  1.56  1 .26  1.30  1.47  0.76  1.23  1.04  1.14  1.18  1 .14  1.35  2.18  0.B1  0.40  5.33  Placrietite  3.25  3.16  3.32  3.03  1.22  3.18  3.04  3.16  3.07  3.02  2.31  3.20  2.93  3.41  6.55 5.74  Ilmenite  1.41  1.29  1.50  1.12  1.37  1.31  1 .14  1.29  1.18  1.10  1.01  1.35  0.99  1.61  Hematite  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.00  0.X  0.44  0.00  0.00  0.00  0.00  Pyrite  0.00  0.00  0.00  0.04  0.00  1 .61  0.00  0.00  0.O2  0.00  0.00  0.07  0.51  0.00  0.02  1.  Chemical analyses by Department of Oceanography, The U n i v e r s i t y of B r i t i s h Columbia.  2.  Normative minerals c a l c u l a t e d at the Computing C e n t r e , The U n i v e r s i t y of B r i t i s h Columbia.  3.  T o t a l i r o n expressed as Fe203.  4.  L . O . I . = Loss on i g n i t i o n .  C a l c u l a t i o n s were made u i t h Fe = 0.899BFe2D3 ( I r v i n e and Baragar,  1971).  F  F i g u r e 3.32. AFM d i a g r a m f o r i g n e o u s r o c k s i n t h e D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. H a z e l t o n Group v o l c a n i c r o c k s a r e g e n e r a l l y c a l c - a l k a l i n e and t h e T e r t i a r y d y k e p l o t s i n t h e tholeiitic field. L i n e s e p a r a t e s t h o l e i i t i c from c a l c - a l k a l i n e r o c k s ( I r v i n e and B a r a g a r , 1 9 7 1 ) . A = Na20 + K20; F = 0.8998 F e 2 0 3 ; M = MgOj a l l a r e i n w e i g h t p e r c e n t . Symbols u s e d a r e as f o l l o w s : O = H a z e l t o n Group v o l c a n i c r o c k s , • = a v e r a g e c o m p o s i t i o n o f H a z e l t o n Group v o l c a n i c r o c k s i n t h e D o l l y V a r d e n camp,A= T e r t i a r y dyke.  68  12  -  10  FOIOITE  9 O CM  RHYOLITE  8 -  + o CM o z  6 -  PICROSASALT  37  F i g u r e 3.33. T o t a l a l k a l i s i l i c a (TAS) d i a g r a m f o r t h e D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. H a z e l t o n Group v o l c a n i c r o c k s are g e n e r a l l y b a s a l t i c - t r a c h y a n d e s i t e s . The T e r t i a r y d y k e p l o t s in the p i c r o b a s a l t f i e l d . V o l c a n i c r o c k names and t h e c h e m i c a l c l a s s i f i c a t i o n i s a f t e r L e Bas e t a_l. ( 1 9 8 6 ) . Symbols a r e as i n F i g u r e 3.32.  69  F i g u r e 3.34. S i 0 2 v s Z r / T i 0 2 d i a g r a m f o r t h e D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. H a z e l t o n Group v o l c a n i c r o c k s a r e g e n e r a l l y andesites. The T e r t i a r y d y k e p l o t s i n t h e a l k a l i b a s a l t f i e l d . The f i e l d s f o r common v o l c a n i c r o c k s a r e a f t e r W i n c h e s t e r and F l o y d (1977). Symbols a r e as i n F i g u r e 3.32.  70  Using  the t o t a l  classification fourteen Dolly  of v o l c a n i c  analyses  3.33).  indicates  f r o m t h e H a z e l t o n Group v o l c a n i c  The  one i s t r a c h y d a c i t e ,  different  d y k e , however,  alteration.  This  depicted  discriminating elements,  composition  shows t h a t  a chemical  and z i r c o n i u m .  four  and one i s a l k a l i  The S i 0 2 v s Z r / T i 0 2  basalt.  t h e H a z e l t o n Group v o l c a n i c This  and p l o t s  eight of basalt,  The a v e r a g e rocks  classification from H a z e l t o n  i n the probable extension  71  problem,  scheme o f  are sub-alkaline  t h e T e r t i a r y dyke i s d i f f e r e n t  rocks  that are  immobile  ( F i g . 3.34) shows t h a t  are andesite,  confirms  f o r the  i s basalt.  To overcome t h i s  rock types using  V a r d e n camp t o be a n d e s i t e .  volcanic  classification  ( s e c t i o n 3.2.5),  (1977) e s t a b l i s h e d  such as t i t a n i u m  i s trachyandesite  rocks  t h e wide range o f c h e m i c a l  on t h e s e d i a g r a m s .  o f W i n c h e s t e r and F l o y d  Dolly  The T e r t i a r y d y k e  e i t h e r metamorphism o r h y d r o t h e r m a l  altered volcanic  analyses  rocks  i s e r r o n e o u s and t h e p r o p e r  may e x p l a i n  W i n c h e s t e r and F l o y d  one  and one i s t e p h r i p h o n o l i t e  This  b a s e d on p e t r o g r a p h y  probably mobile during  fourteen  i n the  three are  AFM and TAS d i a g r a m s , however, u s e e l e m e n t s  analyses  rocks  f r o m t h e H a z e l t o n Group v o l c a n i c  i n the p i c r o b a s a l t f i e l d .  classification,  plot  ( L e Bas e t a l . , 1 9 8 6 ) , f o u r o f  they a r e b a s a l t i c - t r a c h y a n d e s i t e .  plots  Tertiary  f o r the chemical  The a v e r a g e c o m p o s i t i o n o f t h e v o l c a n i c  chemically  and  rocks  (TAS) d i a g r a m  two a r e b a s a l t i c - a n d e s i t e , two a r e b a s a l t , one i s  trachyandesite,  is  silica  V a r d e n camp a r e b a s a l t i c - t r a c h y a n d e s i t e ,  andesite,  (Fig.  alkali  i n the also Group  of the a l k a l i  basalt  field.  As d i s c u s s e d  previously,  this classification i s  e r r o n e o u s and t h e T e r t i a r y d y k e i s a b a s a l t , petrography  In  (section  3.2.5).  summary, H a z e l t o n G r o u p v o l c a n i c  V a r d e n camp- a r e c a l c - a l k a l i n e b a s a l t s chemical  similarities  north-central  British  basalt  volcanic  calc-alkaline  Rossland Formation  3.4  STRUCTURE  single the  ranging  analogous  syncline, Kitsault  (Souther,  Dolly  Varden  deposits  These  Jurassic  Yakoun  1977; F o r s t e r ,  Formation  1984).  Volcanic  ( F i g s . 3.1  and s e d i m e n t a r y beds o f f o l d s with  t o 3.5).  Thus,  gentle, sedimentary  o f t h e T o r b r i t Mine l i e i n t h e c o r e o f a  valley.  (East  from  V a r d e n camp i s d o m i n a t e d by a  w h i c h when p r o j e c t e d River  i n composition  to other Early  H a z e l t o n Group form b r o a d u p r i g h t  rocks exposed east  t y p i c a l of  Bonanza V o l c a n i c s ,  i n the Dolly  plunges  1976).  i n t h e C a n a d i a n C o r d i l l e r a , namely  phase o f d e f o r m a t i o n .  northwesterly  suites of  on s t r a t i g r a p h i c l o c a t i o n .  suites  and  and R i c h a r d s ,  show t r e n d s  terranes,  Toodoggone V o l c a n i c s ,  geometry  with  (Tipper  the  Fold  and a n d e s i t e s ,  Columbia  chemically volcanic  i n the Dolly  H a z e l t o n Group v o l c a n i c  t o r h y o l i t e , depending  rocks are also  rocks  to other  H a z e l t o n Group r o c k s g e n e r a l l y calc-alkaline  b a s e d on  t o the northwest,  Mineralized  s t r a t i f o r m horizons of the  and W e s t ) , N o r t h s t a r ,  o c c u r on t h e s t e e p l y  T o r b r i t and Moose-Lamb  north-dipping,  72  follows the  western  limb of  this  syncline.  This simple  fold  picture,  however, i s  c o m p l i c a t e d by  numerous s t e e p l y - d i p p i n g b l o c k  all  and  rock u n i t s  Reliable  bedding  compositional alignment  Synsedimentary rocks of u n i t  primarily  lapilli  deformation  more c o m p e t e n t  and  and  8 are  fragments  60 d e g r e e s . such  as  Sedimentary that  are both  planar  to the  bedding resulted  and  from  folds.  Axial  foliations  fault  and  planes  and  foliations,  rock u n i t s  and  show o n l y c r u d e l y d e v e l o p e d  into  whereas  b l o c k s has  fracture  73  exceed  occurred,  steeper dips  are  units.  prominent  are  foliations axial  subparallel  to  probably  of the beds d u r i n g in a l l  generally trend  northeastern dips.  incompetent  fracture  anticlines  seldom  however, o c c u r  and  the  broader,  approximately  that  flattening  and  Sedimentary  that  i n t u f f a c e o u s r o c k s and  steep to v e r t i c a l  slaty  rock  rocks e x h i b i t  in fine-grained,  developed  limbs  areas,  to bedding  plane  volcanic  with  Torbrit  Foliation  dewatering  and  northwesterly  are w e l l  volcanic  subparallel  metamorphism.  plane  the  i n the v o l c a n i c  occur primarily  sedimentary  are r a r e .  Where marked r o t a t i o n o f  consequently  units,  of northwesterly t r e n d i n g  i n t h e N o r t h s t a r and  observed  difficult.  disharmonically folded,  s y n c l i n e s w i t h m o d e r a t e d i p s on  cut  i n the t u f f a c e o u s u n i t s .  rock u n i t s are deformed  a series  that  from  i n sedimentary  structures  tightly,  volcanic  forming  correlation  measurements were o b t a i n e d  layering,  of t u f f  open f o l d s  make s t r a t i g r a p h i c  faults  Axial  sedimentary  units  cleavages; volcanic  units  cleavages.  Bedding  lineation  on  axial  plane  sedimentary rocks, northwest.  to the  foliation  by  an  faulting  abrupt  step-like photos. In  fold  and  southwest-northeast  Block  i n the  degrees to  map-area a r e  a x i s as  joints  are  directed  i n the  easily  D o l l y Varden area  recognized  both  ( F i g . 3.35).  w h i c h a p p e a r t o be appear  i s generally  i n the  faults  now  plane  o f t e n marked by  some c a s e s ,  they  direction,  compression.  have e i t h e r n o r m a l o r  that  the  dilational  a-c  faults  so  the  a l l r e l a t e d t o a major  change i n l i t h o l o g y ,  cliffs,  i n the  These  rotated  primarily in  commonly o r i e n t e d i n a n o r t h e a s t e r l y  perpendicular Folds,  recognized  p l u n g e s c o n s i s t e n t l y 25  Most j o i n t s  fractures,  cleavage,  t o be  parallel  field  reverse  and  on a i r  movements.  normal c o u l d  reverse  defined  have b e e n  ( c f . McKlay.,  1 984 ) .  Faults  are  d o m i n a t e d by  their  formation  units  (especially  earlier the  faults  faults  discussed  The  and  can  by  5.2).  the  Red  defined  younger  in section  s e t of  Red  the  faults  Point  relative  the  timing  Schematic  of  displacements  stratiform layers),  and  of  of  r e c o n s t r u c t i o n of  stratiform horizon  ( F i g . 5.2)  is  5.2.  trends  northwest;  Moose-Lamb f a u l t s  Gold-silver-copper and  by  faults.  D o l l y V a r d e n and  Point  d i r e c t i o n s , and  mineralized  mineralized  earliest  and  the  in detail  i n c l u d e the  be  two  veins,  Extension  74  s u c h as  examples  (Figs.  those  prospects,  3.1,  3.4  discovered  at  are s u b p a r a l l e l  F i g u r e 3.35. W e l l d e v e l o p e d a - c j o i n t s , o r i e n t e d 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 , and p e r p e n d i c u l a r t o t h e n o r t h w e s t e r trending fold axis.  75  to  these  faults  e a r l i e r northwest-trending  t r e n d n o r t h - n o r t h e a s t and  physiography faults 3.1,  include  3.4  and  principally and  drainage  5.2).  commonly  as  those  follow  the  P e r v a s i v e and  activity.  controlled  i n the D o l l y  of r e g i o n a l  Other  phenocrysts  hydrothermal  sericitization associated to  be  degree all  and  with  completely by  both s t r i k e - s l i p metal  subparallel  hydrothermal  to  and  primarily  to  and  silicification,  obscured  sericitization.  styles.  this  the  mafic  fabrics  of style.  widespread  l a t t e r more  Late carbonate  76  the  alteration  invariably  of hydrothermal  by  saussuritization  silicification,  Pyrite  the  hydrothermal  e p i d o t e from  include  Original by  due  i s characterized  types  alteration Pervasive  i s t y p i c a l of  fractures.  the e a r l i e r e f f e c t s  faults is  V a r d e n camp.  plagioclase;  alteration  three a l t e r a t i o n  (Figs..  faults.  metamorphism and  development of c h l o r i t e , carbonate  plagioclase  faults  MINERALIZATION  fracture  anorthitic  the  These  silver-base  later north-northeast  Propylitic alteration  m i n e r a l s and  suggest  d y k e s and  a l t e r a t i o n predominates,  combined e f f e c t s  influenced  along these  of the Wolf d e p o s i t , a r e  VEIN  l a t e r set of  Mitchell  displacement  Tertiary  a l l rock units  propylitic  Hanson and  Apparent  ALTERATION AND  affects  have s t r o n g l y  r i g h t - l a t e r a l ; slickensides  such  The  p a t t e r n s i n the map-area.  the Campbell,  d i p - s l i p motion.  veins,  3.5  and  faults.  of and  the  commonly rocks  to a  tends  lesser  i s associated stringers  a c t i v i t y i n a l l rock  with  overprint units.  Footwall volcanic moderate, p r o p y l i t i c more a b u n d a n t immediate Minor  2b.  In  rocks  (units  3)  the  of  (unit  5),  rather  and  hematite.  and  unit  in  5)  early  footwall  i n the  from  pale  The  for  (Tipper  and  (units  6 and  7)  No  propylitization  1976).  display  the  observed  be  8b  and  8c  host  hydrothermal and/or  horizon  to  (unit  with p y r i t e  in  have  been  unit  4.  with  Maroon  pyritized  carbonate,  sericite  c h a r a c t e r i s t i c maroon  conditions  related  might a l s o  to  indicate  subsequently  criterion,  same p e r v a s i v e , footwall  locally  the  deposited  however,  is  history rocks  units  1 and  2.  represent rocks  (unit  abundant p y r i t e , which  might  synsedimentary.  77  a  moderate  carbonatization on  color  deposition  Other hangingwall v o l c a n i c  and  (unit  i s associated of  unit  volcanic  mineralization  such a d e p o s i t i o n a l  hydrothermal a l t e r a t i o n e f f e c t s Units  the  single of  the  s i l i c i f i e d nor  eruptions  i n the  Moderate s e r i c i t i z a t i o n  8).  tuff  maroon c o l o r  interpretation Richards,  stratiform  extensively  subaerial  generally  sequence, h a n g i n g w a l l  neither  oxidizing  display  within  stratiform  grey ash  imparts  a marine environment.  reliable  especially  Northstar deposits,  however, a r e  diagenesis.  2b)  however, i s  Sericite invariably  Hematite  source  and  is associated  overlying  implies  2a  Pyrite,  2b,  also  have been a l t e r e d  5 and  volcanic  the  1,  mineralized  V a r d e n and  pyrite  but  to  and  the  sericitized.  q u a r t z and tuffs  to  4 and  Dolly  extremely  of  2a  silicification  contrast  (units  alteration.  in units  footwall  3).  rocks  sedimentary  Tertiary  dykes  alteration. lesser  This  zeolite,  ( u n i t 9) show s l i g h t i s represented  i n pervasive  t o moderate  by c h l o r i t e  alteration  recrystallization,  mineralized  evident,  there  chlorite  as  Unit  3 i s also hydrothermally  a r e t h e main a l t e r a t i o n  i s quite  altered, i n a  rocks.  minerals  S e r i c i t e and  associated  with the  mineralization.  Group r o c k s .  and o c c u r  associated with Wolf d e p o s i t ,  especially  i n Hazelton  significant  as s t r u c t u r a l l y  silver,  controlled  Examples o f t h i s  and T i g e r  prospects  l e a d and  deposits  type  and t h e D a v i d C o p p e r f i e l d , M i t c h e l l ,  this  rock  carry  replacement.  Musketeer, S u r p r i s e Generally,  veins  either  These a r e d e t a i l e d below.  S i l v e r - b a s e metal veins  specific  of the  m i n e r a l i z a t i o n i n t h e D o l l y V a r d e n camp o c c u r s  values  growth  Although  s i l v e r - b a s e metal or g o l d - s i l v e r - c o p p e r  zinc  style  due t o t e c t o n i s m  but l e s s e r degree than the host  stratiform  Vein  (unit 3).  of the minerals  with  does n o t appear t o have been major  remobilization. similar  such as g r a i n  dominates the a l t e r a t i o n  stratiform horizon  recrystallization  and c a l c i t e ,  and a m y g d u l e s .  D e f o r m a t i o n and m e t a m o r p h i c t e x t u r e s , and  propylitic  (Figs. 3.1  i n c l u d e the North and 3 . 4 ) .  type of m i n e r a l i z a t i o n i s not r e s t r i c t e d  u n i t , but the permeable  the ash t u f f s  tuffaceous  o f u n i t 7b, a r e f a v o r e d .  78  t o any  rocks, This  feature  of host rock p r e f e r e n c e along with widespread a l t e r a t i o n of the enclosing  host rocks t o m i n e r a l i z a t i o n , has l e a d t o the  nomenclature of "replacement v e i n s "  The  s i l v e r - b a s e metal v e i n s  (Thiersch,  1986).  s t r i k e northeast  and d i p s t e e p l y  to the east and west, s u b p a r a l l e l t o the youngest s e t of f a u l t s i n the a r e a . up  Veins vary i n t h i c k n e s s  to s e v e r a l meters a c r o s s ,  of the v e i n s  from l e s s than one meter  and a r e u s u a l l y d i s c o n t i n u o u s .  a t the Wolf d e p o s i t  v a r i e s between 2 and 8m i n  width and was t r a c e d f o r over 250m along i t s l e n g t h 1986).  (Thiersch,  M i n e r a l i z a t i o n c o n s i s t s of a quartz-carbonate gangue,  with l o c a l c o n c e n t r a t i o n s hosting  One  of b a r i t e and/or w i t h e r i t e and j a s p e r ,  p y r i t e , l e s s e r s p h a l e r i t e and galena, sparse  c h a l c o p y r i t e and t r a c e s of p y r a r g y r i t e , t e t r a h e d r i t e and n a t i v e silver.  B a r i t e i s r a r e l y completely r e p l a c e d  by p y r i t e .  v a l u e s a r e g e n e r a l l y e r r a t i c as i n d i c a t e d by d r i l l i n g Wolf d e p o s i t described for  (Thompson and Pearson, 1981).  by T h i e r s c h  and  the other v e i n o c c u r r e n c e s of t h i s type, i n c l u d e  bands of grey, white and j a s p e r o i d q u a r t z , w e l l t e r m i n a t e d quartz c r y s t a l s . wallrock  fragments e n c l o s e d  Breccia  a t the  Open space  (1986) f o r the Wolf d e p o s i t  Metal  textures, recognized  colloform  comb s t r u c t u r e s and textures,  primarily  by v e i n m a t e r i a l , a r e common.  Hydrothermal a l t e r a t i o n r e l a t e d t o the s i l v e r - b a s e metal mineralizing  systems i s dominated by s i l i c i f i c a t i o n and  p y r i t i z a t i o n i n poorly defined The  envelopes are c h a r a c t e r i z e d  envelopes surrounding the v e i n s . by i n t e n s e  79  bleaching  of the host  rocks and  and  local  limonite  footwall alteration  stain. was  No  d i f f e r e n c e i n hangingwall  noted at  the  Wolf d e p o s i t  (Thiersch,  1986).  Gold-silver-copper Belt,  an  area  3.36), w h i c h andesite  of  alteration  veins  occur  c h a r a c t e r i z e d by  within  a very  the  prominent  i s r e l a t e d to hydrothermally u n i t 7a  ( F i g s . 3.1  associated with  and  this  D o l l y Varden gossan  3.4).  Hydrothermal  zone i s e x p r e s s e d e i t h e r  and  pyritization  ( F i g . 3.1:  u n i t 7a(q))  sericitization  and  pyritization  ( F i g . 3.1:  unit  steep  gold-silver-copper  northeasterly  dips  generally  from a  few  abundant c h a l c o p y r i t e h o s t e d w i t h i n  a silicified  gangue.  ratio  Typical  mineralized  exhibiting  zones a r e  open space  Examples of  this  McPhee, Red  Point,  Patch prospects sericitization  overall  fracture f i l l i n g  Point  ( F i g s . 3.1 and  and  chloritization  general,  hydrothermal a l t e r a t i o n  sericitization  of  the  occurrence  3.4).  immediately  ( F i g . 3.1:  Belt area,  an  are  and  ( F i g . 3.37).  includes  the  Maud Dan  Silicification, the  i n the  main e x p r e s s i o n s to the  Gold  7a(s)).  veins;  but  of in  Belt  i s dominated  In the  central part  intensely s i l i c i f i e d  80  pyrite  i s 7 to  C o m b i n a t i o n and  adjacent  unit  i s mainly  vein-fillings  textures  Extension,  alteration  by  to gold  stockworks or  wallrock  Gold  silver  type of m i n e r a l Red  mineralogy  with  and  The  Vein  northwest  to tens  chloritized  meters.  or  7a(s)).  strike  widths ranging  as  centimeters locally  of  veins  and  (Fig.  altered porphyritic  silicification  The  Gold  zone  (Fig.  3.1:  1.  unit and  7 a ( q ) ) c h a r a c t e r i z e d by barite,  possibly represents  hydrothermal  system, o f t e n  B u c h a n a n , 1981  the  was  Gold  surface  and  geochemical gold  trending  discovered  Belt  area  sampling At  the  outlined  t h a t measured  15.5g  gold  per  s h o w i n g was the 3.7m  north  i n width,  values 3.1  and  of  of  the  silica  zone, a p p r o x i m a t e l y a recent  channel  Red  Point  quartz  a  cap  (cf.  of  the  and  600m i n  e x p l o r a t i o n program  This  program  sampling  of  prospect  (Figs.  and  3.1  zone, a m i n e r a l i z e d  38m  long  and  samples  at  gold  grades  the  Red  zone. 3.6g  were a l s o d i s c o v e r e d  at  Point This  gold the  3.4).  81  this  3.4),  5.7g  was gold  assayed  mineralized  Extension  tonne.  and  showing  showing  Another  showing  per  and  wide, g r a d i n g  taken across width.  soil  o l d trenches  gold  4.6m  in  involved  this  t o n n e o v e r a 2.0m  discovered  end  a  levels  g e o l o g i c a l mapping, r o c k  and  s o u t h end  One  gold  ( D e v l i n , 1986).  near the  tonne.  uppermost  r e f e r e d t o as  during  underground  showings.  per  the  white  ).  A northwest length,  stockworks of milky  prospect,  i s 50m  in  length,  Significant  Combination prospect  near  gold  (Figs.  F i g u r e 3.36. The very prominent gossan of the D o l l y Varden Gold B e l t , near Black Bear'Creek ( F i g s . 3.1 and 3.4). T h i s zone i s r e l a t e d to h y d r o t h e r m a l l y a l t e r e d grey-green p o r p h y r i t i c a n d e s i t e ( u n i t 7a).  82  F i g u r e 3.37. G o l d - s i l v e r - c o p p e r v e i n s of the D o l l y Varden G o l d B e l t . T y p i c a l m i n e r a l i z e d zones are q u a r t z stockworks and v e i n f i l l i n g s .  83  4.0  4.1  INTRODUCTION  Stable prove that  and  radiogenic  the  and  H a z e l t o n Group.  carbon  depositional  depositional  isotopes  of  stable  isotopes  the  age  data,  critical  of  wallrocks  Dolly  o x y g e n and  q u a r t z and  V a r d e n camp  of  of the  the  Varden  (<T)  rocks  sulfur,  carbonates  and  barite.  (3)  and  stratiform  (2)  the the  Radiogenic  source of  b o t h K-Ar  lead  in  lead helped  to  mineralization.  detailed geologic  studies,  model f o r s t r a t i f o r m  was  mineral  camp.  CARBON ISOTOPE STUDIES  carbon  isotopes  were a n a l y z e d  c a r b o n a t e from d e p o s i t s  ( F i g . 3.1  deviation  <S =  source of  d i f f e r e n t components o f  i n r e f i n i n g a genetic  SULFUR, OXYGEN AND  barite,  the  is  s u l f u r , oxygen  mineralization,  the  isotopes  combined w i t h  i n the  Sulfur,  (1)  of  l e a d were u s e d t o d e t e r m i n e t h e  resolve  mil  The  p a r t i c u l a r l y s u l f i d e s vs.  radiogenic  deposits  to  to Middle J u r a s s i c v o l c a n i c  temperature of  and  Isotopic  were u n d e r t a k e n  i n s u l f i d e s , b a r i t e , q u a r t z and  galena,  4.2  Early  environments of  mineralization,  also  studies  c a r b o n were u s e d t o d e t e r m i n e :  o x y g e n and the  isotope  stratiform silver-lead-zinc-barite mineralization  contemporaneous w i t h the of  ISOTOPE STUDIES  and  from a  Table  4.1).  standard  within  Data are  calculated  {(RSample - R S t a n d a r d ) / ( R S t a n d a r d ) } x  84  in sulfide,  the  Dolly  reported  as  as: 1 ,000  ( %• ),  per  where RSample RStandard and  i s 34S/32S, 180/160 o r 13C/12C i n t h e sample and  i s the corresponding  Rye, 1979; T a y l o r , 1 9 7 9 ) .  troilite  (CDT) f o r s u l f u r ,  o x y g e n , and U n i v e r s i t y for in  carbon.  _+0.1 %» , r e s p e c t i v e l y o  4.2.1  Table from  i n quartz  for sulfide  of sulfur  i n F i g u r e 4.1.  Barite  i n the s u l f i d e  minerals  have <f34S v a l u e s similar  range  either  values  very  occur  The i s o t o p i c i s t y p i c a l of  massive s u l f i d e  i s isotopically  d e p o s i t s where  that cluster  around  t o m e t e o r i t e s and  (Ohmoto a n d Rye, 1 9 7 9 ) .  t o +25.1 p e r m i l . H i g h  deposits.  1987).  samples i n  h a s c o n s i d e r a b l y h i g h e r df34S v a l u e s , r a n g i n g  typical  and  S u l f i d e rf34S v a l u e s  n e g a t i v e ; more p o s i t i v e  characteristically  rocks  values  i s _+ 0.2%o  and b a r i t e  V a r d e n E a s t a n d Wolf d e p o s i t s .  zero per m i l , which  also  a t 1 sigma o f cf34S  (K. M u e h l e n b a c h s , p e r s . comm.,  values displayed for volcanogenic  igneous  for  Isotopes  t o zero or s l i g h t l y  sulfides  (SMOW)  (H. R. K r o u s e , p e r s . comm., 1 9 8 7 ) , and  4.1 a r e p l o t t e d  composition  Diablo  P e e d e e B e l e m n i t e (PDB)  a n d <fl3C i n c a r b o n a t e s ,  isotope values  the Dolly  +12.6  Mean Ocean Water  standard,  (Ohmoto  a r e Canon  -7.0 t o +20.4 p e r m i l , w i t h most o f t h e v a l u e s  close in  cfl 80  Sulfur  Sulfur  Standard  of Chicago  and b a r i t e ,  f o r the standard  The s t a n d a r d s  The r e p r o d u c i b i l i t y  sulfides  +0.14% for  ratio  of sulfate  These v a l u e s  positive  minerals  d34S v a l u e s  i n volcanogenic  from  for barite are massive  sulfide  a r e g e n e r a l l y c l o s e t o contemporaneous  85  TABLE 4.1.  Sulfur, oxygen and carbon isotope compositions of s u l f i d e s , b a r i t e , quartz and  c a l c i t e i n deposits from the Dolly Warden Camp, northwestern B.C. plotted on Figure 3.1.  Sample  Deposit  mineral  Number  Name  Analyzed  d34S1 fr>  CDT  0272a 0272a 0272a  Dolly Varden West Dolly Varden west Dolly Varden west  Barite  +25.1  DV-2 DV-2  Dolly Varden East  Pyrite  DV-2 D258 D258  Sphalerite Galena  Dolly Varden East  Sphalerite  Dolly Varden East Dolly Varden East  Pyrargyrite Pyrite  -3.5 +11.4  Dolly Varden East  +1.8  Dolly Varden East  Sphalerite Galena  D258  Dolly Varden East  Calcite  D258  Dolly Varden East Northstar  Quartz Pyrite  D333b-1 D333b-1 D333b-1  Northstar Northstar Northstar  Sphalerite Galena Barite  0333b-1  Northstar  Quartz  D333b-2 D333b-2  Northstar Northstar Northstar Torbrit  Sphalerite Galena Barite Pyrite Sphalerite Galena Barite Quartz Sphalerite Galena Barite Pyrite Sphalerite Galena Witherite Calcite  D333b-2 D326-1 D326-1 D32B-1 D326-1 D326-1 D32B-2 D326-2 D326-2 41081-14 41081-14 41081-14 41081-14 41081-14 41081-14 41081-24 D72a T248  Torbrit Torbrit Torbrit Torbrit Torbrit Torbrit Torbrit Wolf Wolf Wolf Wolf Wolf Wolf Wolf Tiger Red Point Extension  Quartz Pyrite Quartz Quartz  cfl801,2 %. SNOW  rfl803 Ore F l u i d s  <f!3C1 %* PDB  -1.1 -2.0 +9.2 +3.6  0258  D333b-1  Sample locations are  Data are plotted i n Figures 4.1 and 4.2.  +11.7  +1.5 to +11.8  +7.8 +9.0  -4.2 to  +5.2  +11.2  -5.2 to  +6.1  +10.8  +0.6 to +10.9 -3.0 to +8.4  -4.5 -4.7 -5.2 +12.B  +13.1 -1.2 -0.8 +15.9 +0.4 -3.8 -7.0 +13.6 -0.9 -2.9 +14.6 +20.4 +3.0 +8.9  n.d.  n.d. +12.7  -3.4 to  +8.0  n.d.  +10.2 +13.0 +15.4  -0.5 to +8.3 -0.3 to +9.2 -0.7 to +10.7  +15.9 +6.9  -0.2 to +11.2 -9.1 to +2.2  +16.0  1.  Isotopes of s u l f u r from s u l f i d e s and b a r i t e , oxygen from b a r i t e and carbonate, and carbon from c a l c i t e were analyzed by H.R. Krouse, Department of of Physics, University of Calgary, Calgary, Alberta T2N 1N4; CDT = Canyon Diablo t r o i l i t e standard; SmOW = Standard mean Ocean Water; PDB = University of Chicago standard, Peedee Belemnite.  2.  Isotopes of oxygen from quartz were analyzed by K. muehlenbachs, Department of Geology, University of Alberta, Edmonton, Alberta T6G 2E0; n.d. = not determined.  3.  Calculated from the dl80 values of b a r i t e , quartz and carbonate using oxygen isotope f r a c t i o n a t i o n equations i n Appendix "JJ. Calculated range of ore f l u i d compositions are calculated from the temperature range of 143oC t o 375oC (estimated i n Table 4.2 from s u l f u r and oxygen isotope data for pairs of s u l f u r and oxygen compounds from the Dolly Varden camp).  4.  Data i s also i n Thiersch (1986).  86  6 S, °/oo 34  DOLLY VARDEN E A S T  NORTHSTAR A  A  •  BARITE  A  SPHALERITE  •  GALENA  •  PYRITE  •  TORBRIT  PYRARGYRITE  WOLF  Range of seawater sulfate at approx. 190  c  Ma  F i g u r e 4.1. S u l f u r i s o t o p e p l o t f o r d e p o s i t s f r o m t h e D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. The r a n g e f o r e a r l y J u r a s s i c seawater s u l f a t e i s seawater s u l f a t e i s from C l a y p o o l e t a l . , 1980. D i a g r a m shows a d o m i n a n t l y magmatic o r i g i n f o r t h e s u l f i d e s (rf34S =• 0% ), and an o r i g i n f r o m o x y g e n a t e d s e a w a t e r o f E a r l y J u r a s s i c age ( c a . 190 Ma) f o r b a r i t e (df34S = 1 5 % „ ) . o  87  oxygenated marine  sulfate  Kaplan, the  seawater  minerals i n equilibrium  samples  range o f seawater  Temperatures compounds u s i n g camp  temperatures  Pacific  from  w i t h i n the  the E a r l y  from p a i r s  Jurassic  of  close  from  temperatures  sulfur  isotope Most o f  low o r h i g h , s u g g e s t i n g precipitation.  f o r e x c e p t i o n a l p a i r s of  Varden  t o : (1) e x i t  (Styrt  et a l . ,  Rise  camp  (143oC a n d  temperatures  from  sulfur  and Drenchwater These  1981),  (2) f l u i d  (150oC t o 360oC) d e t e r m i n e d  (Kusakabe  Japan,  et a l . ,  375oC),  (260oC t o 350oC) Rise,  inclusion  f o r s u l f i d e and  and a n h y d r i t e s from  sulfate the East  1982; P i s u t h a - A r n o n d a n d Ohmoto,  temperatures  (115oC t o 305oC)  isotope data f o r sphalerite-galena stratiform,  zinc-lead-barite  Creek d e p o s i t s ,  temperatures  sulfur  a n a l y s e s from t h e D o l l y  and non-contemporaneous  the Dolly  the M i s s i s s i p p i a n  1980).  isotope  i n Kuroko d e p o s i t s ,  calculated  Creek  during  are u n r e a l i s t i c a l l y  1983) and (3) d e p o s i t i o n a l  from  camp f a l l  Most o f  i n a c t i v e h y d r o t h e r m a l v e n t s on t h e E a s t P a c i f i c  latitude  minerals  1 980).  ( F i g . 4.1).  4.1) c a l c u l a t e d  disequilibrium,  however, f a l l s  21oN  ( H o l s e r and  e q u a t i o n s ( A p p e n d i x J ) a r e i n T a b l e 4.2.  compounds  measured  Varden  precipitated  the s u l f u r  range of c a l c u l a t e d  sulfur  w i t h seawater  o f d e p o s i t i o n as i n d i c a t e d  temperatures  isotopic The  the D o l l y  sulfate  (Table  fractionation these  from  a t a p p r o x i m a t e l y 190 Ma  Varden  age c u r v e s f o r  1 966 i n Faure', 1 977; C l a y p o o l e t a l . ,  barite  period  as r e p r e s e n t e d by i s o t o p e  are also  88  A l a s k a (Lange  i n close  pairs  Red Dog et a l . ,  agreement w i t h t h e  TABLE 4.2. B.C.  Calculated depositional temperaturesl for pairs of sulfur and oxygen compounds from the Dolly Varden Camp, northwestern  Sulfur and oxygen isotope data used i n estimates are i n Table 4.1.  depositional temperatures—see text.  Underlined values represent p o t e n t i a l l y r e a l i s t i c  Variation i n estimated temperatures are due to a n a l y t i c a l error i n the s u l f u r and oxygen  analyses and i s approximately + 30oC.  Temperature (oC) Sample  Deposit  Barite-  Barite-  Barite-  Pyrite-  Pyrite-  Sphalerite-  Quartz-  Quartz-  Quartz-  Number  Name  Galena  Sphalerite  Pyrite  Galena  Sphalerite  Galena  Calcite  Barite  Uitherite  Witherite  143  192  152  108  D272a  Dolly Varden West  0V-2  Dolly Varden East  Calcite-  623 -41  D258  Dolly Varden East  D333b-1  Northstar  2B3  349  D333b-2 D32B-1  Northstar  311  354  Torbrit  227  346  D326-2  Torbrit  290  405  41081-1  Wolf  375  53  17  74  934  957  929  190 c.i.2  1071 532  96  -5  25  -141  202 328 77  174  1.  Calculated from the d34S values for s u l f i d e s and b a r i t e , and the 0*180 values for quartz, b a r i t e and carbonates, using s u l f u r and oxygen isotope f r a c t i o n a t i o n equations i n Appendix T_.  2.  c i . = calculation invalid.  temperature plotting  (270oC) d e t e r m i n e d  t h e FeS  on a p o r t i o n  1959).  The  indicated  content of s p h a l e r i t e  of the system  argentite-silver  sulfur may  as a s u l f u r  310oC.  near  isotopic  I f so, c a l c u l a t e d  depositional  temperatures.  samples  study  formation could  of the D o l l y  pairs  Varden  of camp  a t the time of  temperatures  parts  4.1).  approximate  Pacific  camp r a n g e  sulfate  Ocean  from the E a s t  p e r m i l (Kusakabe  observed  from:  (Sakai,  Pacific et a l . ,  of Kuroko  1977  Rise,  Sakai,  +6.9  1983),  which  t o those of range  from  +10.2  to  S i m i l a r v a l u e s were and h a n g i n g w a l l  (Matsukuma and  T s u t s u m i and Ohmoto,  Horikoshi, 1983;  (2) q u a r t z and h e m a t i t e samples  90  of  i n Kusakabe e t a l . ,  1982).  deposits  K u s a k a b e and C h i b a , 1983;  Watanabe and  from  i n p r e s e n t - d a y s u r f a c e water  (1) v o l c a n o g e n i c s u l f a t e s  ferruginous cherts  carbonate  Most o f t h e a*180 v a l u e s a r e  The <fl 80 v a l u e s a r e a l s o v e r y c l o s e  anhydrites  and  p e r m i l , t h e a n a l y z e d v a l u e o f BaS04  from d i s s o l v e d  the c e n t r a l 1 982).  i n the D o l l y Varden  per m i l (Table  t h a n +9.6  prepared  1970;  later  compositions of quartz, b a r i t e  from d e p o s i t s  t o +15.9  +11.5  the  Oxygen I s o t o p e s  Oxygen i s o t o p e  higher  deposit  (Campbell,  Thus t h e e x c e p t i o n a l  equilibrium  deposition.  4.2.2  barometer  of the data i n t h i s  compounds a n a l y z e d i n d e p o s i t s  h a v e been  by e m p l o y i n g  the temperature of s p h a l e r i t e  r a n g e b e t w e e n 230oC and  f o r m a t i o n by  from the T o r b r i t  ZnS-FeS-S, and  assemblage  uncertainties  that  for sphalerite  from  the et  B i g Mike v o l c a n o g e n i c massive al.,  1984),  analyses  et a l . ,  4.2) u s i n g  Realistic  compounds r a n g e calculated  from  camp  for pairs  (143oC t o  equilibrium. generally  from which  Oxygen i s o t o p e  calculated  temperatures  from  of f l u i d  mineral-water temperatures isotopic of  sulfur  used  systems.  temperature  f o r oxygen t h e range of  Varden  deposits  oxygen-bearing minerals are i n isotopic  compositions of the ore f l u i d s are  the  dfl80 v a l u e s a n d f i l l i n g of e i t h e r  fractionation  In t h i s  the oxygen-bearing  factors  study, because  f o r various the f i l l i n g  i n c l u s i o n s were n o t m e a s u r e d , t h e o v e r a l l r a n g e o f 143oC t o 375oC e s t i m a t e d f o r p a i r s  i n the c a l c u l a t i o n s . range  equations  compounds f r o m t h e  f o r the Dolly  and o x y g e n compounds f r o m  temperature  isotope  temperatures  of s u l f u r  pairs  ore minerals, together with the  determined  of f l u i d  from  fractionation  they p r e c i p i t a t e d  inclusions  minerals or associated experimentally  calculated  375oC).  <f 1 8 v a l u e s o f o r e f l u i d s  the s o l u t i o n s  O n t a r i o ( B e a t y and  the oxygen  c a n be e s t i m a t e d i f i t i s assumed t h a t and  of the Kidd  152oC t o 190oC, a n d a r e w i t h i n  temperatures  Varden  depositional  i n Nevada (Rye  1980).  ( F i g . 4.1) and o x y g e n i s o t o p e  (Appendix X ) •  The  (Table  zones  deposits,  o f d e p o s i t i o n were a l s o  o x y g e n compounds  Dolly  sulfide  1979, 1980 i n F r a n k l i n  Temperatures of  deposit  and (3) o r e s and a l t e r a t i o n  Creek v o l c a n o g e n i c massive Taylor,  sulfide  the Dolly  Varden  camp was  The c l o s e a p p r o x i m a t i o n o f t h i s  to those of s u l f i d e  91  and s u l f a t e m i n e r a l s i n  K u r o k o d e p o s i t s and o n t h e E a s t in  determining  fluids.  oxygen  i n Table  4.1, a r e p l o t t e d  for ore fluids  t o seawater  the h e a v i e r coincident  equations  isotope compositions  range from  w i t h most o f t h e v a l u e s close  of the ore used  either  with  those  4.2.  centered  or s l i g h t l y  f o r Kuroko d e p o s i t s  (1979) f o r magmatic w a t e r s ,  compelling with  No s y s t e m a t i c  are largely  (Pisutha-Arnond,  Figure  from t h e D o l l y Varden  variation  between d e p o s i t s  minerals  the  D o l l y Varden  camp.  Since  i s o t o p e exchange i n hydrothermal  possible  oxygen  was o b s e r v e d  a f u n c t i o n o f temperature  f o r oxygen  ( T a y l o r , 1979),  temperatures  from  systems i s i t s h o u l d be for the  i n t h e D o l l y V a r d e n camp f r o m t h e r a n g e o f  determined  by s u l f u r  and oxygen  geothermometry and t h e c o r r e s p o n d i n g ore fluids  camp  sampled  isotope data  t o e x t r a p o l a t e the temperature o f formation  mineralization  the  p r e s e n t e d by  4.2 shows t h a t t h e most  and  largely  analyzed  enriched i n  and a s m a l l p a r t o f t h e lower  c o i n c i d e n c e t o be o f d a t a  seawater.  T h erfl80  on z e r o , w h i c h i s v e r y  The range o f v a l u e s  range f o r metamorphic waters.  camp,  -9.1 t o +11.8 p e r m i l  (SMOW i n F i g . 4 . 2 ) ,  oxygen i s o t o p e .  i nFigure  1983); t h e upper p a r t o f t h e r a n g e o v e r l a p s those Taylor  i n the  of the ore f l u i d s  f o r m i n e r a l i z a t i o n i n the D o l l y Varden  calculated  i t s use  a r e i n Appendix J .  Calculated responsible  Rise j u s t i f i e s  isotope compositions  Oxygen i s o t o p e f r a c t i o n a t i o n  calculations  values  t h e oxygen  Pacific  ( F i g . 4.2).  Thus,  isotope  calculated  d*180 v a l u e s f o r  i f the oxygen-bearing  minerals  -20  -10  0  +10  +20  8 O, ° / o o 1a  F i g u r e 4.2. Range o f c a l c u l a t e d 4*180 v a l u e s f o r o r e f l u i d s ( T a b l e 4.1) r e s p o n s i b l e f o r m i n e r a l i z a t i o n i n t h e D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. T e m p e r a t u r e s o f 143oC and 375oC were e s t i m a t e d f r o m s u l f u r and o x y g e n i s o t o p e d a t a f o r p a i r s o f s u l f u r a n d o x y g e n compounds ( T a b l e 4.2) f r o m t h e D o l l y V a r d e n camp. D i a g r a m ( m o d i f i e d f r o m T a y l o r , 1979) a l s o shows SM0W ( S t a n d a r d Mean Ocean W a t e r ) , t h e c a l c u l a t e d f i e l d s o f p r i m a r y magmatic and m e t a m o r p h i c w a t e r s , k a o l i n i t e and m e t e o r i c w a t e r l i n e s , and a p l o t o f t h e r a n g e o f dD o f f l u i d i n c l u s i o n s v s . c a l c u l a t e d <fl 80 v a l u e s f o r K u r o k o v o l c a n o g e n i c m a s s i v e s u l f i d e deposits (Pisutha-Arnond and Ohmoto, 1983 ). Th'is p l o t s t r o n g l y s u p p o r t s a d e r i v a t i o n f r o m h o t s e a w a t e r ( c a . 245oC) o f t h e o x y g e n i s o t o p e s i n b a r i t e , c a r b o n a t e and q u a r t z .  93  were p r e c i p i t a t e d  from  seawater,  i s o t o p e d a t a on b a r i t e ,  as e s t a b l i s h e d  the temperature  by  the  sulfur  o f f o r m a t i o n was  about  245oC.  4.2.3  Carbon  Carbon samples  Isotopes  i s o t o p e c o m p o s i t i o n s were d e t e r m i n e d  from the D o l l y  dfl3C i n ( T a b l e Ore -5  deposits parts  4.1)  Varden  a r e -9.8  i n which  Sedimentary  above c l e a r l y The  t o have formed  ore d e p o s i t s  marine  c a r b o n a t e s and  f o r C02 (Faure,  per m i l .  from  (Ohmoto  seawater  None o f t h e  and have  origins  compositions obtained  however, a r e w i t h i n  in fluid  from  more n e g a t i v e t h a n  with reduced carbon  the carbon i s o t o p e  dfl 3C v a l u e s ,  per m i l range  inclusions  t h e -4  t o -12  f r o m most  parts  hydrothermal  1977).  Discussion  Mineralization precipitates of  generally  biogenic,  to zero parts  explain  Values of  per m i l , r e s p e c t i v e l y .  whereas v a l u e s i s o t o p i c a l l y  rfl 3C v a l u e s c l o s e  4.2.4  deposits.  p r o c e s s e s , o r have a metamorphic o r i g i n  1979).  here.  -11.8  calcite  c a r b o n a t e m i n e r a l s h a v e <fl3C v a l u e s n e a r  magmatic c a r b o n a r e e i t h e r  Rye,  and  per m i l are i n t e r p r e t e d  magmatic f l u i d s ,  biologic  E a s t and Wolf  for  seawater  i n v o l c a n o g e n i c massive  a d j a c e n t t o v e n t s near and  between s e a w a t e r  hydrothermal sulfate  and  sulfide  the s e a f l o o r  solutions.  Since  h y d r o t h e r m a l H2S  94  deposits  due  to mixing  equilibrium does  not occur  generally, minerals  the isotopic  reflects  composition  the i s o t o p i c  composition  of s u l f u r  al.,  T h e r e f o r e , n e a r l y z e r o df34S v a l u e s o f s u l f i d e s i n  Dolly  Varden d e p o s i t s suggest  primarily  from  andesitic  volcanic rocks.  the  sulfides,  either  a magmatic  with  i n the  solutions  the  t o mixing  in sulfide  hydrothermal 1981).  prior  of s u l f u r  that sulfur source  Slightly  d e r i v e d from  Alldrick,  V a r d e n camp  sulfate  the h i g h p o s i t i v e sulfate  essentially  origin  values.  identical  seawater  A seawater  for  sulfur  i s i n d i c a t e d by  Seawater  isotopic  for sulfur,  s e a w a t e r , h a v e been o b s e r v e d i n  similarly values  values  Jurassic  Rise  (Styrt  e t a _ l . , 1981;  Kuroko s u l f a t e s  reflect  ( K u s a k a b e and C h i b a , 1983;  1983).  source  Varden ores  the b a r i t e .  compared  units  e t a l . , 1986; Dawson  for barite  t o normal  sulfate  Watanabe and S a k a i ,  Dolly  rock  d*34S v a l u e s w h i c h a r e c l o s e t o E a r l y  Kusakabe e t a l . , 1982);  in  fluids  h o r i z o n and v o l c a n i c h o s t  (Alldrick  s u l f a t e d e p o s i t s on t h e E a s t P a c i f i c  Miocene  f o r many o f  1986).  A seawater  seawater  the underlying  negative biogenic  the sedimentary  the mineralized stratiform  rocks of the D o l l y and  o r from  however, may mean t h a t t h e h y d r o t h e r m a l  probably  underlying  (Styrt et  was d e r i v e d  negative values  i n c o r p o r a t e d m i n o r amounts o f t y p i c a l l y sulfur,  seawater  f o r oxygen i n b a r i t e , i s c o n s i s t e n t with  quartz  the s u l f u r  and  isotope data  The <fl 80 v a l u e s , however, a r e s l i g h t l y  to present-day  seawater.  95  Taylor  carbonate  (1979) n o t e d  enriched that  equilibrium  isotopic  temperature  dependent.  isotopes oxygen  fractionation  Varden East  fluids  during  of heavier  may h a v e b e e n c a u s e d by  seawater  sulfate  the  surface  and  seawater.  sulfur  for sulfide  and Wolf d e p o s i t s  from e i t h e r  sulfur.  subsurface  Rise  Mike c u p r i f e r o u s v o l c a n o g e n i c  deposits  Wolf d e p o s i t s  massive and  in calcite  from  between v o l c a n i c s source f o r from a c t i v e f o r the B i g  deposit  (Rye e t  volcanogenic  t h e D o l l y V a r d e n E a s t and  more n e g a t i v e  rocks.  of seawater  This  than  seawater and  carbon  isotope  through the underlying a n d e s i t i c  i s supported  to 0.9 parts per m i l ) f o r c a l c i t e basalts  by b a c t e r i a a t  o f t h e Red Dog C r e e k and D r e n c h w a t e r  are i s o t o p i c a l l y  circulation  volcanic  from  et a l . , 1981), sulfide  between  derived i n  for sulfides  m i g h t be due t o t h e d e p l e t i o n o f t h e h e a v i e r during  mixing  (Lange e t a l . , 1 9 8 0 ) .  «fl3C values  The  (Styrt  and f o r t h e s t r a t i f o r m  zinc-lead-barium Creek areas  either  interaction  has b e e n s u g g e s t e d Pacific  from t h e D o l l y  o r magma a n d i n p a r t  A c o m b i n e d magmatic and s e a w a t e r  on t h e E a s t  temperature.  S u l f u r was p r o b a b l y  w h i c h h a d been r e d u c e d  i n sulfides  1984),  minerals  appear t o r e p r e s e n t  volcanic rocks  or during  s e a w a t e r and  conditions of increased  obtained  magmatic and s e a w a t e r  al.,  enrichment  i s o t o p e e x c h a n g e between o x y g e n a t e d  P o s i t i v e values  vents  i s largely  i n the oxygen-bearing minerals  hydrothermal  part  Therefore,  f o r oxygen  of the Miocene Macquarie  96  by s i m i l a r  <3(l 3 C v a l u e s  i n hydrothermally Island ophiolite,  (-14.6  altered south  o f New  Zealand  4.2.5  (Cocker  e t aj.., 1 982).  Summary  Stable the D o l l y  isotope data Varden  from  sulfide  camp g e n e r a l l y  and gangue m i n e r a l s  support a dual source  "ore" m i n e r a l i z a t i o n .  A dominantly  sulfur  contrasts with a probable  for  i n the s u l f i d e s  sulfur  Sulfur  and oxygen i n b a r i t e ,  isotopes of s u l f i d e s  a m i n o r component sulfur  oxygenated  seawater  then that  the b a r i t e  f o r the  seawater  show them t o be m a i n l y sulfur.  reflect  seawater,  magmatic  an o r i g i n Jurassic  associated  origin  gangue.  On t h e o t h e r  closely  of appropriate Early i s from  f o r the  q u a r t z and c a r b o n a t e  of sedimentary  isotopes i n barite  magmatic o r i g i n  from  with  hand,  from  age.  Given  gangue  m i n e r a l s p r o b a b l y a r e t o o . Thus, oxygen i s o t o p e s i n b a r i t e , q u a r t z and c a r b o n a t e origin,  4.3  are compatible  and were d e r i v e d f r o m  POTASSIUM-ARGON  4.3. from  for  seawater.  a g e s on s a m p l e s  from  the Dolly  camp a r e l o c a t e d on F i g u r e 3.1 and p r e s e n t e d i n T a b l e One sample o f f e l d s p a r - h o r n b l e n d e p o r p h y r i t i c  the footwall volcanic  prospect, of  h o t ( c a . 245oC)  marine  ISOTOPES  Whole-rock potassium-argon Varden  with a sedimentary  near  the T o r b r i t  72.2 + 2.5 Ma. samples  from  Similar  sequence  i n the v i c i n i t y  mine, y i e l d e d  97  of the Tiger  a L a t e C r e t a c e o u s age  Late Cretaceous  the hangingwall volcanic  andesite  a g e s were sequence,  determined which  TABLE 4.3. Whole-rock potasium-argon datal for uolcanic rocks from the Dolly Varden camp, northwestern B.C.  Sample locations are  plotted on Figure 3.1.  40Ar *  Location Rock name and rock unit2  Sample  AOAr* -i  55K  Apparent  number  lat(oN) long(oUl)  T37a  55.6B  129.50  Feldspar-hornblende porphyritic andesite (unit 2a)  3.35 0.01  0.878  9.590  72.2 + 2.5  Late Cretaceous  DVB4-NS1  55.68  129.51  S e r i c i t i z e d andesite ash t u f f (unit 4)  4.18  0.844  11.713  70.7 + 2.5  Late Cretaceous  0.07 0.871  10.246  68.1 + 2.5  Late Cretaceous  22.3 + 0.8  Miocene  D35  55.68  129.50  (±)  Andesite l a p i l l i tuff (unit 5)  3.80  40Artotal  "i  106 cm3 STP/g  age ( F l a ^  Time5  0.03 G19  55.68  129.51  Basalt (unit 9)  0.676 0.005  0.523  .5905  1.  Argon analyses are by J . Harakal and potassium analyses are by K. Scott; a l l analyses were done at the Geochronology Laboratory, The University of B r i t i s h Columbia.  2.  Units are described i n Chapter 3.  3.  A r * indicates radiogenic argon.  4.  Constants used are from Steiger and Jager (1977):\e = 0.581 x 10-10 yr-1 ;\fi  5.  Time designation i s from Palmer (1983).  = 4.962 x 10-10yr-1; 40K/K = 1.167 x 10-4.  included  a 70.7  immediately age  f o r an  Torbrit was  overlying andesite  mine.  obtained  An  lapilli  the  t h e age  Dolly  the of  and  of  22.3  +_ 0.8  (Devlin  for similar  Stewart  rocks,  however, a r e  t o o young  Middle  Jurassic  accepted  of  Ma stratiform  and  Godwin,  Tertiary  dykes of  i n the  Alice  the  stratiform dates  i n comparison  1986).  Kitsault  River area.  Therefore,  a direct  measurement o f t h e age  obtained  for  Group r o c k s  interpretation of host  to  mineralization in  to the E a r l y  f o r the Hazelton  Ma  the  v o l c a n i c r o c k s were e x p e c t e d  Late Cretaceous  tuff  +_ 2.5  (D. Brown, p e r s . comm.,  r o c k s h o s t i n g the  V a r d e n camp.  a 68.1  southeast  i n the v i c i n i t y  andesitic  age  a n d e s i t e ash  dyke t h a t c r o s s c u t s  ages d e t e r m i n e d  of  situated  i s i n c l o s e agreement w i t h  P r e m i e r - S i l b a k mine, n e a r  reveal  tuff  M i o c e n e age  ( C a r t e r , 1982)  Analyses  for a sericitized  the N o r t h s t a r d e p o s i t  This date  area  age  t h e N o r t h s t a r d e p o s i t and  Early  of  potassium-argon Arm  Ma  for a basaltic  mineralization 1986b).  +_ 2.5  these  to i n the  of the dates  rocks appears  to  been c o n d u c t e d  on  as  be  invalid.  Potassium-argon whole-rock feldspar  Early and  s a m p l e s and  mineral  the nearby  a n a l y s e s have a l s o on  separates  Stewart  area  to Late Cretaceous  are  hornblende, obtained  (Smith,  by  from  1977;  and  potassium  v a r i o u s rock  Alldrick  units  in  e t a l . , 1987).  a g e s were r e p o r t e d f o r s e v e r a l s a m p l e s  somewhat y o u n g e r t h a n  ages d e t e r m i n e d  biotite  Late T r i a s s i c  uranium-lead  d a t i n g of  99  to E a r l y  Jurassic  z i r c o n s f o r the  same  rock units Alldrick  (Alldrick  e t a_l.  increases for  lower  1 9 6 6 ) ;  potassium-argon  dates reset  by  regional  facies  increases  potassium-argon  argon  and  possibly  loss  and  within  sericite,  sufficient resetting  of  T h e r e f o r e , t h e same argument p r o v i d e s an  of the D o l l y  ( c a . 7 0 Ma.)  altered  Varden  potassium-argon  isotope r a t i o s ,  the D o l l y  plotted  H a z e l t o n Group  camp, y i e l d  only  Late  dates.  on  Varden  on g a l e n a s a m p l e s camp  conventional lead  from  ( F i g . 3 . 1 and  i s o t o p e diagrams  2 0 8 P b / 2 0 4 P b v s 2 0 6 P b / 2 0 4 P b and  206Pb/207Pb)  i n Figure  samples mines  collected  4.3.  previously  (Godwin e t a l . ,  Table  4.4  lists  lithology,  are  206Pb/208Pb vs  i s o t o p e a n a l y s e s on  from  the D o l l y  Varden  in this  galena  and  Torbrit  study;  they  quality.  t h e sample number, d e p o s i t  deposit  deposits  (207Pb/204Pb v s  Lead  1 9 8 0 ) were n o t u s e d  c o n s i d e r e d t o be o f p o o r  five  T a b l e 4.4),  206Pb/204Pb,  host  that  LEAD ISOTOPES  Lead  are  using  where a r g o n i s  They a l s o a r g u e d  the lower g r e e n s c h i s t  rocks c h a r a c t e r i s t i c  by  temperature  metamorphism p r o v i d e s  to cause  dates.  e x p l a n a t i o n o f why  4.4  metamorphism.  1 9 8 6 ) .  varied  (Armstrong,  greenschist  Cretaceous  the  o f t h e same r o c k u n i t  m i n e r a l s , s u c h as b i o t i t e  temperature  Brown, p e r s . comm.,  concept  during  certain  D.  to explain  d a t e s f o r samples  "metamorphic v e i l "  d r i v e n o f f and  1 9 8 6 ;  attempted  ( 1 9 8 7 )  potassium-argon the  et a l . ,  t y p e and  the B r i t i s h  100  name,  Columbia  location, Mineral  TABLE 4 . 4 . G a l e n a - l e a d Isotope analyses! from the Dolly Varden camp northuestern B . C . Sample l o c a t i o n s are p l o t t e d on Figure 3 . 1 . t  H O  Sample  Deposit  NTS  acni  Lat.o Long.o  Nunber  Name  Nap  Numbers  North litest  Data are p l o t t e d i n F i g u r e 4 . 3 .  Lead Isotope R a t i o s (one sigma Lithology  Deposit type  206Pb/2O4P8  207Pb/204Pb  208Pb/204Pb  uncertainty) 206Pb/207Pb  206Pb/20BPb  30555-001  Red P o i n t  103P/12E  103P--196  55.69 129.52  a l t e r e d andesite porphyry  Au-Ag-Cu v e i n  38.394  (0.02)  1.20546 (0.01)  0.490034 (0.00)  Red Point  103P/12E  103P--196  55.69 129.52  a l t e r e d andesite porphyry  Au-Ag-Cu vein  18.814 (0.02) 18.824 (0.01)  15.608 (0.02)  30555-001  15.612  (0.00)  38.427 (0.02)  1.20569 ( 0.01)  0.489854 (0.01)  30556-001  Nartfistar  103P/12E  103P--1B9  55.68 129.51  andesite t u f f  s t r a t i f o r m Ag-Pb-Zn-Ba  1B.B74 (0.02)  15.623 (0.01)  38.482 (0.02)  1.20810 ( 0.01)  0.490468 (0.01 )  30557-001  Torbrit  103P/12E  103P--191  55.68 129.50  andesite t u f f  s t r a t i f o r m Ag-Pb-Zn-Ba  18.875 (0.01)  15.625 (0.01)  38.485 (0.02)  1.20805 (0.01)  0.490453 (0.01)  30771 -003  O o l l y Uarden  103P/12E  103P--1BB  55.68 129.51  andesite t u f f  s t r a t i f o r m Ag-Pb-Zn-Ba  1B.B52 (0.01)  15.612  (0.01)  38.452 ( 0.01)  1.20753 (0.01)  0.490274 (0.01)  30771-004  D o l l y Uarden  103P/12E  103P--188  55.6B 129.51  andesite t u f f  s t r a t i f o r m Ag-Pb-Zn-Ba  1B.B9B (0.01)  15.624  (0.01)  38.519 (0.01)  1.20955 (0.00)  0.490617 (0.01)  30904-001  Wolf  103P/12E  103P--198  55.71 129.52  andesite t u f f  Ag-Pb-Zn-Ba v e i n  IB.859 (0.01)  15.613  (0.01)  38.464 ( 0.01)  1.20789 (0.00)  0.490291 (0.01)  AUG D o l l y Uarden Camp (n = 7)  103P/12E  mineralization  18.857 (0.01)  15.617  (0.01)  38.460 (0.02)  1.20747 ( 0.01)  0.49D2B4 (0.01)  AUG J u r a s s i c (n = 8)2  IB.818 (0.02)  15.611 (0.00)  38.437 (0.03)  1 .20544 ( 0.00)  0.489567 (0.00)  AUG T e r t i a r y  19.148 (0.04)  15.622  38.629 (0.04)  1.22572 (0.00)  0.4956B4 (0.00)  1.  55.69 1 29.51 andesite  (n = 12)2  (0.00)  A l l sample p r e p a r a t i o n and analyses are by J . E . G a b i t e s and were done i n the Geochronology Laboratory, Department of G e o l o g i c a l S c i e n c e s , The U n i v e r s i t y of B r i t i s h Columbia. were analyzed u s i n g phosphoric a c i d and s i l i c a g e l , measured on a Vaccuum Generators Isomass 54R s o l i d source mass spectrometer l i n k e d to a Hewlett-Packard HP-B5 computer. judged to be of good q u a l i t y .  2.  Abbreviations used i n table a r e : NTS = National Topographic Survey, DCCII = B r i t i s h Columbia Mineral Inventory,  Data from Stewart mining camp ( A l l d r i c k et a l . , 19B7).  AUG = Average.  Lead isotope  ratios  A l l analyses are  Inventory  (MINFILE) number f o r e a c h  were o b t a i n e d f r o m  stratiform  and  sample a n a l y z e d .  vein  mineralization within andesite tuff, veins  hosted  by  altered  isotopic  ratios  deposits  i n the Stewart  also  included i n Table  The  isotopic  Figure  4.3.  from  mining  plotting  A l l lead  Zartman  and  which are p l o t t e d  on F i g u r e  Growth c u r v e s  of Stacey  they  would p r e d i c t  Oliver  (1982) a l s o  galena-lead  the  lead  mineral  e t a l . , 1987)  cluster  i n the c l u s t e r ,  Kramers  (1975) and  (1979; 1 9 8 1 ) ,  1  on  plot  the  segments  and  K r a m e r s and  the  "orogene"  mineralization.  this  from from  for  because  a p r e l i m i n a r y study  of  123  d e p o s i t s w i t h i n the  these deposits occur and  of  4.3.  a f u t u r e model age noted  below  "orogene"  Varden data  Intermontane B e l t  are  Varden  not a p p l y to the D o l l y  isotope analyses  Intermontane B e l t ;  Tertiary  (Alldrick  isotope values  evolution  c u r v e do  and  average  w i t h i n the d i s t i n c t  and  evolution  The  of g a l e n a - l e a d i n the D o l l y  the growth c u r v e of S t a c e y c u r v e o f Doe  and g o l d - s i l v e r - c o p p e r  Jurassic camp  barite  4.4.  composition  ores are uniform,  silver-lead-zinc-  andesite porphyry.  f o r galena  Samples  in similar  most were h o s t e d  t e r r a n e s of  i n Hazelton  Group  rocks.  Lead  i n the D o l l y  principally 1979  and  from  an  Varden d e p o s i t s appears  average  1981), which  orogene r e s e r v o i r  is typical  t o be d e r i v e d (Doe  of a mature i s l a n d  102  and arc  Zartman, setting  comprised  The  close  that  a l l mineral  and p e l a g i c  isotope  deposits  mineral deposits  lead  i n the Dolly  i n the Stewart mining  deposits  d a t e them on a " f i n g e r p r i n t "  Deposits isotopes,  separated  from  the Dolly  formed d u r i n g  Jurassic.  this  Note t h a t  The d a t a  also from  plot  very  Jurassic  camp, w h i c h a r e d i s t i n c t  deposits  directly, their  lead  basis.  V a r d e n camp, on t h e b a s i s  fall  i n cluster  c l u s t e r of lead  ( c f . A l l d r i c k e t a l . , 1987).  galena-bearing  camp f o r m e d c o g e n e t i c a l l y r o c k s a t about  with  deposits  event  values These  ( c f . Chapter of the Dolly  c a l c - a l k a l i n e Hazelton  190 Ma.  103  of lead i n the  1 ( F i g . 4.3),  isotope  the hypothesis espoused elsewhere that  association  i n the Stewart area, e f f e c t i v e l y  a short-lived mineralizing  they  from another  thesis  volcanic  V a r d e n camp a r e  r a t i o s do n o t p r o v i d e a b s o l u t e model a g e s f o r t h e  known J u r a s s i c  support  4.3  ( A l l d r i c k e t a l . , 1987). A l t h o u g h ,  formation of these mineral deposits  Tertiary  i n Figure  i s o t o p i c r a t i o s f o r galena  from T e r t i a r y d e p o s i t s  with  sediments.  data  c l o s e l y g e n e t i c a l l y and i n a g e .  t o average  isotope  crust,  c l u s t e r of galena-lead  suggests related  of continental  from results 3) i n Varden Group  F i g u r e 4.3. P l o t s o f 208Pb/204Pb v s . 206Pb/204Pb 207Pb/204Pb v s . 206Pb/204Pb and 206Pb/208Pb v s . 206Pb/207Pb f o r d e p o s i t s l o c a t e d on F i g u r e 3.1 and l i s t e d i n T a b l e 4.4 .•= d e p o s i t s f r o m t h e D o l l y V a r d e n camp O= d e p o s i t s w i t h J u r a s s i c l e a d s i g n a t u r e andQ= d e p o s i t s w i t h T e r t i a r y l e a d s i g n a t u r e f r o m t h e S t e w a r t camp ( A l l d r i c k e t a l . , 1 9 8 7 ) . C l o s e d symbols r e p r e s e n t group means. F r a c t i o n a t i o n s l o p e and P b e r r o r were d e t e r m i n e d u s i n g e q u a t i o n s from R i c h a r d s (1983). A n a l y t i c a l e r r o r shown i s 2 f f r o m 46 a n a l y s e s o f t h e B r o k e n H i l l g a l e n a s t a n d a r d (BHS-UBC1). The g r o w t h c u r v e marked "S & K" i s a f t e r S t a c e y and K r a m e r s ( 1 9 7 5 ) ; t h e e v o l u t i o n c u r v e marked " o r o g e n e " i s " V e r s i o n 1" a f t e r Doe and Z a r t m a n ( 1 9 8 1 ) . The f i e l d o f p e l a g i c s e d i m e n t s i s a f t e r Doe and Zartman (1979 and 1 9 8 1 ) . /  f  104  5.0  5.1  GENESIS OF  STRATIFORM  MINERALIZATION  INTRODUCTION  Several  t h e o r i e s have been proposed  mineralized Dolly nature  stratiform  V a r d e n camp. by  (1951),  Campbell  t o be  replacement-vein Tertiary  (1959) and  time.  instead.  comprise  fluids  into  products  This study,  i n the  "bedded v e i n s " .  (1962) c o n s i d e r e d  Mitchell  related  them  Cretaceous  (1973) f a v o r e d  them t o  an  Jurassic  however, i n d i c a t e s  m i n e r a l i z a t i o n probably  the v o l c a n i c s t r a t i g r a p h y .  used  here,  refers  the hydrosphere  of  but  the  t h a t most  formed  as  d e r i v e d , submarine e x h a l a t i v e d e p o s i t s t h a t  p a r t of  "exhalative"  Similarly, origin  silver-lead-zinc-barite hydrothermally  Skerl  of  stratiform  d e p o s i t s formed d u r i n g e i t h e r  epithermal-replacement volcanism  represented  genesis  Group r o c k s  (1921) i m p l i e d t h e i r  that they  Black  or E a r l y  deposits i n Hazelton  Hanson  suggesting  f o r the  the  to the  (Franklin  e x h a l a t i v e process  The  localized  term e x p u l s i o n of  e t a l . , 1981),  are  called  and  exhalites  (Ridler,  1973).  5.2  PHYSICAL AND OF  THE  STRATIFORM  A stratiform supported  CHEMICAL  by  occurrences  and  field can  be  CHARACTERISTICS  MINERALIZATION  volcanogenic  mapping, which  origin  deposits i s  shows t h a t t h e main  r e c o n s t r u c t e d t o one  105  f o r these  continuous  ore  mineral horizon  that  conforms  to bedding.  cross-section 5.1), 3c:  As i l l u s t r a t e d  f o r t h e D o l l y V a r d e n camp  conformity  hypothesis.  stratigraphic green  (Figs.  Another  rocks,  important  (unit  rocks  tuffs  4) a l s o b e a r c l o s e r e s e m b l a n c e  overly  tuffs  ( u n i t s 4, 5 and 6 b ) .  thought  t o be e x h a l a t i v e  s t r a t i f o r m and v o l c a n o g e n i c  1973).  In general,  described  the i d e a l i z e d  deposits  maroon t u f f s  mainly  t o s i l i c e o u s and  layers that  commonly  elsewhere  (Ridler,  stratigraphic synthesis  stratiform  3.13).  most w i d e l y  enclose tuff  c a n be  mineralized  horizons.  w h i c h a r e u n c o n f o r m a b l y o v e r l a i n by black  mineral  shale  The  evident  recognized  (Large,  from a p y r i t e - r i c h  t o p , has been r e c o g n i z e d  1977).  base t o a  i n some o f t h e  o f t h e D o l l y V a r d e n camp a n d i s  in drillcore  Vertical  epiclastic  and s i l t s t o n e .  zonation,  ore deposits  particularly  that  and a s s o c i a t e d p y r i t i c  galena-sphalerite-rich  deposits  pyritic  a r e c a p p e d u n c o n f o r m a b l y by s e q u e n c e o f f l o w s a n d  tuffs,  Vertical  (Fig.  tuffaceous  a s a f o o t w a l l s e q u e n c e o f i n t r u s i o n s and t u f f s ,  stratiform  rocks,  (unit 5).  Hangingwall  deposits  u n c o n f o r m a b l y o v e r l a i n by maroon t u f f s  related  -  sequence between a  within  hangingwall  pyritic  t o 3.5, a n d  i s the c o n s i s t e n t  2b) a n d a maroon h a n g i n g w a l l  Fragments o f s t r a t i f o r m o r e a l s o o c c u r  (unit  3.1  i s key support f o r  feature  p o s i t i o n of the mineralized  footwall  idealized  o f s t r a t i f o r m m i n e r a l i z a t i o n ( u n i t s 3a, 3b and  s e c t i o n 3.2) t o e n c l o s i n g h o s t  this  i n an  mineral  from t h e N o r t h s t a r  zoning  features  i s probably  of volcanogenic  deposit  one o f t h e  exhalative  S t r a t i f o r m o r e u n d e r l a i n by s t o c k w o r k  1  0  6  WEST  EAST  F i g u r e 5.1. I d e a l i z e d c r o s s - s e c t i o n o f t h e D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. The s e c t i o n , drawn l o o k i n g n o r t h , a p p r o x i m a t e s the r e l a t i o n s h i p s of the i n v o l v e d E a r l y t o M i d d l e J u r a s s i c H a z e l t o n Group r o c k s but i s n o t drawn t o s c a l e ; e f f e c t s o f f o l d i n g and f a u l t i n g h a v e b e e n removed. Units are described i n F i g u r e 3.4. Ore d e p o s i t s , w i t h i n t h e i r r e s p e c t i v e e x h a l i t e f a c i e s ( c f . F i g . 5 . 3 ) , a r e : 1 = D o l l y V a r d e n West, 2 = D o l l y V a r d e n E a s t , 3 = N o r t h s t a r , 4 = T o r b r i t , and 5 = Moose-Lamb. Abbreviation: u = unconformity. 107  ore, and  as  represented  pyrite  footwall rocks,  volcanogenic  mineralrzation  i n the  represents  Vertical  mineral  footwall  alteration,  the  lateral  5.1),  characteristic type  of  stockwork  D o l l y Varden East  source  area  deposit  of m i n e r a l i z a t i o n .  been documented i n the  equivalent ore  in  feature  s t o c k w o r k m i n e r a l i z a t i o n and  have not  d e p o s i t s , s u c h as  of  evidence  zonation  of  gangue m i n e r a l s  2km,  zones v a r y deposit  across  from the  (Figs.  3.9  quartz-carbonate-barite  to  for a volcanogenic  the  (Figs.  reflected the  intense  other  the  Torbrit  in silver  to  3.18).  grades  and  Moose-Lamb.  Torbrit,  and  lode  mineralization grade of  the  15g  the  Dolly  and Varden  the 3.12  to  and  3.15),  also is per  405g s i l v e r  per  tonne f o r  the  13 5g  per  tonne f o r  the  D o l l y Varden East the  per  tonne.  108  tonne  deposit,  quartz-carbonate  D o l l y V a r d e n West d e p o s i t , w h i c h has  silver  to  Moose-Lamb  f r o m 865g s i l v e r  silver  the  Moving 3.4  zonation  l a y e r i s c h a r a c t e r i z e d by of  is  3.1,  Torbrit  Lateral  that vary  of  (Figs.  the  Moving westward from the  stratiform  (Figs.  3.11), t h r o u g h  origin  3.2).  q u a r t z - r i c h lodes  Northstar  D o l l y Varden East,  Northstar  silver  3.16  (Table  map-area  b a r i t e - j a s p e r m i n e r a l i z a t i o n of  deposits  the  or  line  eastward, over  for  vent  intense a l t e r a t i o n  This  the  quartz  Moose-Lamb d e p o s i t s .  Another  the  fracture f i l l i n g  i s another  f o o t w a l l of  zonation,  stratigraphically  East  and  exhalative deposits.  probably  and  disseminated  m i n e r a l i z a t i o n a s s o c i a t e d with  pre-existing, of  by  a  Two  major  contain 3.1  to  layer  the  and  5.2).  separate  In  and  Moose-Lamb Hanson  stratiform Dolly  ore  Fault  (C)  of  experienced Dolly  ( F i g . 5.2  the  scissor-like (2)  asymmetrical  the  earlier  deposits the  1 and  2 and  3 and  4 and  faults  Hanson f a u l t ,  faults  A and  t h a n on  faults  both  Northstar  fault.  109  between  the  ( F i g . 5.2  J:  been  side, i s motion  stratiform horizon  the  and  western  side  between  a l s o by  the  is  between  side  deposits  compared t o t h o s e o f  have  s i d e has  l e s s on  and  East  the  scissor-like  eastern  B),  the  deposits.  with  (distances  B are  the  A and  the  fault  :  include  (5)  to e a s t e r n  this  the  Individual  deposits  western  by  northeasterly  reverse,  respect  of  X  1), D o l l y Varden  (3)  five  first  (C), which appears to  trending  (C)  the  Moose-Lamb  Evidence of  of  this  and  into  ( F i g . 5.2  faults.  deposit  with  D o l l y V a r d e n West and  s i d e of  X:  by  5);  s t r u c t u r a l block  Northstar  to the the  (D)  each  displacement  Hanson f a u l t  deposits  later  about which the  northwest  1 to  (Figs.  stratiform  faults  r o t a t i o n about a p o i n t  and  asterisk).  the  blocks  i s e i t h e r normal or  counter-clockwise an  and  Hanson f a u l t  these  that  deposits  p o s i t i o n , the  D o l l y Varden  ( 3 ) , T o r b r i t (4)  rotation point,  marked by  J:  Campbell  bodies within  Varden East  rotated  faults,  and  displacement  exception  trending  (B)  V a r d e n West  (2), Northstar  east  s t r u c t u r a l blocks  i t s present  b l o c k s . ( F i g . 5.2  northwesterly  trending  of  bound  a p p e a r s t o h a v e been segmented by  earlier  the  faults  stratiform silver-lead-zinc-barite  3.5,  major,  A)  s e t s of  on  shallower the  west  T o r b r i t on  the  dip side  T  F i g u r e 5.2. S c h e m a t i c r e c o n s t r u c t i o n of the m i n e r a l i z e d s t r a t i f o r m h o r i z o n i n t h e D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. X i s p r e s e n t p o s i t i o n o f t h e s t r a t i f o r m h o r i z o n , showing r e l a t i o n s h i p t o b o t h e a r l i e r n o r t h w e s t and l a t e r n o r t h e a s t f a u l t s (cf_. F i g s . 3.1 t o 3 . 5 ) . S c i s s o r - l i k e r o t a t i o n o c c u r s on t h e Hanson f a u l t (A) a r o u n d a p o i n t marked by a s t e r i s k . JX it h e p o s i t i o n o f t h e s t r a t i f o r m h o r i z o n a f t e r movement on n o r t h e a s t t r e n d i n g f a u l t s C and D have been removed. Tn is p r e - f a u l t p o s i t i o n o f t h e s t r a t i f o r m h o r i z o n a f t e r movement on t h e n o r t h w e s t t r e n d i n g f a u l t s A and B h a v e b e e n removed. Faults a r e : A = D o l l y V a r d e n , B = Moose-Lamb, C = Hanson, D = C a m p b e l l . D e p o s i t s a r e : 1 = D o l l y V a r d e n West, 2 = D o l l y V a r d e n E a s t , 3 = N o r t h s t a r , 4 = T o r b r i t , 5 = Moose-Lamb. s  110  Restoration faults (A),  along  the l a t e , northeast  C and D ) , shows t h a t  the Dolly Dolly  Varden East  the  Dolly  Varden f a u l t  Moose-Lamb northeast Dolly  pre-fault  (A), the Northstar form a p l a n e  (A) and Moose-Lamb  form a c o n t i n u o u s length  Isotope  studies  shows t h a t that  stratiform  a l l five  has a  is  very close  are  markedly  Tertiary This  (section  reconstructed  deposits  indicates  than r a t i o s a s s o c i a t e d i n the Stewart area  that  consanguinous with  the enclosing  4.2.1) a l s o  derivation  from  supported  further  isotopes barite  rocks.  Early Sulfur  are consistent  seawater  sulfate.  (section  deposits  which  but which  w i t h C r e t a c e o u s and  ( A l l d r i c k e t a l . , 1987).  to Middle isotopes  Jurassic i n barite  w i t h an E a r l y  Jurassic  A seawater o r i g i n i s  4.2.2 and 4.2.3) by o x y g e n and c a r b o n  i n c a r b o n a t e , q u a r t z and b a r i t e .  precipitated  from t h e  the s t r a t i f o r m m i n e r a l i z a t i o n i s  H a z e l t o n Group v o l c a n i c (section  i n the Dolly  4.4) h a v e a n a r r o w r a n g e ,  t o t h e r a t i o s o f known J u r a s s i c less  deposits  f o r r e s o l v i n g the  i s o t o p i c r a t i o s f o r galena  occurrences  to the  3km.  have b e e n e s s e n t i a l  Lead  (4) and  along the  problem of g e n e s i s of the s t r a t i f o r m m i n e r a l i z a t i o n V a r d e n camp.  side of  i s terminated  (B). Restoration  fault  end o f  (3),T o r b r i t  that  stratiform horizon  of nearly  the east  TT:  (B) f a u l t s t o t h e i r o r i g i n a l  ( F i g . 5.2 JJ"J)  position  (1) a d j o i n s  Varden  ( 2 ) . On t h e n o r t h e a s t e r n  by t h e Moose-Lamb f a u l t  Varden  strike  deposit  (5) d e p o s i t s  ( F i g . 5.2  southwest of the D o l l y  V a r d e n West d e p o s i t  the  faults  f r o m t h e same J u r a s s i c  111  Thus,  i f sulfur i n  seawater as t h e  o x y g e n and must be  carbon  in associated  gangue m i n e r a l s , t h e n t h e y  Jurassic.  T h i s does n o t  conflict  conclusion  that  dominantly  magmatic  sedimentary rocks  sulfur,  (section  Metals Varden  the s u l f u r  in sulfides  and  the r o c k s through  solutions  and  as  or  volcanic  from  the u n d e r l y i n g a n d e s i t i c  stratiform  Ag.  Pb,  Zn, Fe and  These metals  chloride  content  grades  generally  higher  than  igneous  rock type  Amcoff,  1984).  The  found  be due  silver  i n part  in basalts  ( T u r e k i a n , 1972;  Furthermore,  Varden  400g s i l v e r  to the and  the a n d e s i t i c  signature  source  source a l s o  i n the s u l f u r  Depositional  leached  acidic e t a l . , 1981).  per tonne,  higher  a n d e s i t e s than and  t h e amount o f  lead  i n the  f o r metals  i s o t o p e s of  this  i n other  1969  camp i s l o w e r also  in  than f o r probably  (cf_. Solomon, 1 9 7 6 ) . with the  sulfides  magmatic  (section  of the o r e - f l u i d s  112  is  exhalative  1968  Varden  from  fluids  Taylor,  i s compatible  temperatures  lesser  camp o r e s , w i t h  i n volcanogenic  d e p o s i t s i n the D o l l y  andesitic  a  Dolly  with  (Franklin  many v o l c a n o g e n i c e x h a l a t i v e d e p o s i t s , and reflects  Ba,  t o weakly  complexes  i n the D o l l y  i s normally  of  the  were p r o b a b l y  a v e r a g i n g more t h a n  T h i s might  stratiform  ore deposits w i t h i n  which the o r e - f o r m i n g hydrothermal  soluble  concentrations  from  of  transported i n neutral  However, s i l v e r  deposits.  derived either  source w i t h a minor c o n t r i b u t i o n  camp a r e p r e d o m i n a n t l y  circulated,  was  another  4.2.1).  i n the  amounts o f Cu  w i t h from  too  4.2.1).  forming  the  stratiform  mineralization,  temperatures  d e t e r m i n e d by  corresponding fluids,  was  temperature in  calculated  around  (1983),  fluid  Silver  that formed  that  deposits.  5.3  GENETIC MODEL  genetic  precipitation  5.1,  seawater  to the  1955  i n Amcoff,  grades  minerals i n  range  i n the D o l l y  1984),  might  gangue m i n e r a l s on  Varden  favor  circulated  p r o d u c t i o n of Varden  camp  involves of  sulfides  ( F i g . 5.3).  by  the heat of a  in volcanic  The a  cooling,  and  leached  activity,  the  permeable,  ore-bearing hydrothermal  113  camp  case p o r p h y r i t i c a n d e s i t e  through, a l t e r e d The  ore  were p r o b a b l y m o b i l i z e d by  During a l u l l  andesite pyroclastics.  of  to  and v o l c a n o g e n i c  the s e a - f l o o r  driven  i g n e o u s body, i n t h i s 2a).  o f 150o  possibly  i n the D o l l y  model f o r t h e s t r a t i f o r m  ore-forming solutions  unit  Ohmoto  i n c r e a s e s with temperature  convective hydrothermal c e l l ,  (Fig.  sulfate  from e x h a l a t i v e h y d r o t h e r m a l f l u i d s  associated  subvolcanic  and  through a temperature  high s i l v e r  exhalative deposits  exhalative,  the  However,  P i s u t h a - A r n o n d and  higher temperatures  ore  and  i s comparable  S k i n n e r , 1983).  s t u d i e s by  content also  the e x c e p t i o n a l l y  The  of  g e o t h e r m o m e t r y and  temperature  most s u l f i d e  (Tischendorf,  indicating  isotope  the range  isotope values f o r the ore  This  (Ohmoto and  inclusion  indicate  formation  from  o f 250oC assumed f o r t h e f o r m a t i o n o f most m i n e r a l s  Kuroko d e p o s i t s 350oC.  sulfur  oxygen  245oC.  Kuroko d e p o s i t s  detailed  extrapolated  solutions  WEST DOLLY VARDEN WEST CARBONATE FACIES  EAST DOLLY VARDEN EAST SULFIDE FACIES  NORTHSTAR  TORBRIT  CARBONATE FACIES ~  MOOSE - LAMB  •OXIDE  FACIES SEA LEVEL  DISPERSAL BY CURRENTS  F i g u r e 5.3. M o d e l f o r g e n e s i s o f s t r a t i f o r m m i n e r a l i z a t i o n i n t h e D o l l y V a r d e n camp, n o r t h w e s t e r n B.C. Model s u g g e s t s t h a t s u l f i d e s and a s s o c i a t e d gangue m i n e r a l s i n t h e s t r a t i f o r m d e p o s i t s were p r e c i p i t a t e d f r o m h y d r o t h e r m a l s o l u t i o n s e x h a l e d onto the s e a f l o o r . N o t e t h e b a s i n i s a b o u t 3km a c r o s s when r e c o n s t r u c t e d ( c f . F i g . 5.1). N o r t h - s o u t h e x t e n t and v e r t i c a l s c a l e a r e unknown. A b b r e v i a t i o n s a r e : LAM = l a m i n a t e d e x h a l i t e u n i t 3c, MAS = m a s s i v e e x h a l i t e u n i t s 3a and 3b, STK = s t o c k w o r k , SX = s u l f i d e s , SU = s u l f a t e s , CB = c a r b o n a t e s , OX = o x i d e s , QZ = q u a r t z .  114  were s u b s e q u e n t l y by  c u r r e n t s , and  A shallow  presence fossils  finally  i s i m p l i e d by  andesitic  s u b a q u e o u s medium was oxygen-bearing  that  been a v a i l a b l e supports 3km  to a lesser  sedimentary  marine.  The  stratiform  oxygenated, close  site  vertical  The  scale are  under  with anoxic  of  reducing, anoxic  minerals,  sea-water  5.1  by  the  that  the  and  other  and  e n c l o s i n g host  rocks,  must and  have further  The  basin i s  about  t o 5.3),  but o n l y  the  been e x p l o r e d — n o r t h - s o u t h  Precipitation  the quenching  sediment-seawater  oxides  the  extent  and  were e x h a l e d  was  unknown.  stratified,  surface waters.  iron  environment.  b a s i n i n t o which hydrothermal  probably  during  has  indicate  of m i n e r a l i z a t i o n  a c r o s s when r e c o n s t r u c t e d ( F i g s . dimension  the  Marine  abundance of b a r i t e  o r e and  a shallow d e p o s i t i o n a l  east-west  rocks  sulfate-laden  t o the  degree  subvolcanic s i l l s .  gangue m i n e r a l s , m a i n l y  i n the  depressions.  f o r d e p o s i t i o n of  and  i n f l o w s and  i n the o v e r l y i n g  indicates  in sea-floor  dispersed  the e x p l o s i v e c h a r a c t e r of  volcanism,  of amygdules  carbonates,  accumulated  subaqueous environment  mineralization associated  discharged along extensional f a u l t s ,  fluids  bottom waters  of  sulfide minerals  the hydrothermal conditions,  interface.  The  solutions  a t or near  Abundant o x i d e s , p a r t i c u l a r l y  stratiform  m i n e r a l i z e d beds, a l s o  indicates  with  from  hematite, that  oxic  occurred seawater  gangue  subsequently  seawater.  by  the  oxygen-bearing  however, were p r e c i p i t a t e d  115  overlain  oxic  i n the  the  redox  boundary  between a n o x i c  accessible also  and o x i c w a t e r s must have  to the hydrothermal f l u i d s .  This  might  t o t h e marked d e c r e a s e i n m a s s i v e s u l f i d e  away f r o m t h e D o l l y V a r d e n E a s t  Mineral deposits  zoning  within  conditions  changes  be r e l a t e d  mineralization  deposit.  and b e t w e e n m i n e r a l i z e d  o f t h e D o l l y V a r d e n camp c a n be e x p l a i n e d  progressive  been  i n s o l u t i o n chemistry  as t h e h o t e x h a l a t i v e  fluid  stratiform by  and p h y s i c a l  mixes  with  cold  sea-water  on o r n e a r s e a - f l o o r .  The observed related high  development  i n the Northstar to i n i t i a l  and g a l e n a  the deposit  Alteration overall  The minerals  mineral  deposit  ( F i g . 3.13),  the into  s u c h as t h a t  possibly i s  from c o o l e r  (Sato,  from  and s u b s e q u e n t p r e c i p i t a t i o n o f fluids  t o form t h e upper  part  1977; L a r g e , 1977; Ohmoto e t a l . , 1 9 8 3 ) .  accompanied  by r e p l a c e m e n t may a l s o c o n t r i b u t e  to the  zonation.  spectacular  asymmetrical l a t e r a l  among t h e m i n e r a l i z e d  and west exhalative  shape  that  away f r o m t h e D o l l y V a r d e n E a s t fluid  a shallowing  associated  zonation  o f t h e gangue  s t r a t i f o r m D o l l y Varden  however, m i g h t be r e l a t e d t o a b a s i n east  zonation,  p r e c i p i t a t i o n of p y r i t e i n the f o o t w a l l  temperature f l u i d s  sphalerite of  of v e r t i c a l  deposits,  shallows  deposit.  to the Thus, as  moved away f r o m t h e d e e p e r e m a n a t i v e  center  s e a - f l o o r e n v i r o n m e n t , t h e gangue and  s u l f i d e minerals  were d e p o s i t e d  116  and d i f f e r e n t i a t e d  into distinct Ridler,  1970  ore and  represented  by  facies 1973,  an  and  3.1,  Ridler  inner s u l f i d e  marginal  carbonate  an  oxide  outer  (Table  facies  facies  and  and  e x h a l a t i v e vent, Torbrit  and  and  solutions, above the  the  Gustafson,  of  1978).  from r e p e a t e d the ore  Gustafson,  the  silver the  zonation,  distribution. ores  through  the  distal,  of  (Sato,  the  shallower and  ore  a buoyant  important  factors  1977;  that generated  important likely  There  plume in  Turner  the and  resulted  oscillatory  emanative center  factor  i n the  made a m a j o r  i s a decrease  away f r o m t h e  flow  (Turner  and  development  temperature-related,  lower  Since  in silver  content  high grade D o l l y Varden  silver  grade appears to  distribution  a g r a d i e n t i n which  silver  117  i n the  East  and  be  stratiform  grade decreases  of  and  g r a d e D o l l y V a r d e n West  silver  of  c o n t r i b u t i o n to  the moderate t o h i g h grade N o r t h s t a r  d e p o s i t s , to the  imply  to  1978).  Moose-Lamb d e p o s i t s .  may  other  the  and  Dolly  Laminated m i n e r a l i z a t i o n probably  s o l u t i o n s away f r o m  stratiform  Torbrit  proximal  fluids  exhalative pulses  mineral  deposit,  The  l a y e r e d m i n e r a l i z a t i o n of  be  hydrothermal  Temperature, another lateral  can  are  stockwork q u a r t z - p y r i t e  possible formation  e x h a l a t i v e vent,  These  Northstar),  d i f f e r e n c e between s e a - w a t e r  with  cf.  Varden E a s t ) , a  Moose-Lamb).  t o be  whereas t h e w e l l  along  distribution  of  i s considered  Density  1974).  (Dolly  Moose-Lamb d e p o s i t s r e p r e s e n t s  deposition.  t o 3.18;  V a r d e n West and  Varden East d e p o s i t p o s s i b l y o v e r l i e s mineralization  3.9  Shilts,  facies  (Dolly  (Torbrit  Figs.  with  ores  temperature exhalative  as  the hydrothermal  fluids  vent.  118  move away f r o m  the  6.0  Detailed  field  CONCLUSIONS  mapping was p a r a m o u n t  geology  and g e n e s i s  Previous  attempts  of deposits  i n the D o l l y Varden  t o map t h e a r e a  t h e r u g g e d n e s s and i n a c c e s s i b i l i t y  by  inadequate  T h u s , most o f t h e e a r l i e r individual assisted field the  deposits  and p r o s p e c t s  detailed compilation  V a r d e n camp s i n c e  genetic  volcanogenic camp w i t h i n although  present  within  t h e camp.  obstacles  a l s o was t h e f i r s t  strong  volcanogenic  Most o f t h e s i g n i f i c a n t  geological studies models,  Helicoptertwo  and r e s u l t e d i n  study  i n the  models have been  contributions to current  t h e 1970's, a f t e r  completion  i n t h e D o l l y V a r d e n camp.  i t was p o s s i b l e t o d e f i n e  a modern o r e - d e p o s i t  framework.  prospects  This  of  Using i n the  revealed  that:  s i l v e r - b a s e m e t a l and g o l d - s i l v e r - c o p p e r v e i n s a r e  i n t h e D o l l y V a r d e n camp, t h i s m i n e r a l i z a t i o n does n o t  classically  workers; along  area.  of the geology of the D o l l y  m o d e l s were made d u r i n g  earlier  occur  River  camp.  developed.  (1)  compounded  s t u d i e s had t o be l i m i t e d t o  Work by t h e w r i t e r , h e r e ,  the  camp.  hindered  mapping on an o r t h o p h o t o b a s e by t h e w r i t e r o v e r  first  Dolly  of the t e r r a i n ,  b a s e maps f o r t h e K i t s a u l t  s e a s o n s , however, o v e r c a m e t h e s e  Varden  silver  g e o l o g i c a l l y h a d been  by  topographic  i n r e s o l v i n g the  i n epithermal  (2) t h e main m i n e r a l  block  faults  veins,  a s p r o p o s e d by  occurrences  t o f o r m one c o n t i n u o u s  c o n f o r m s t o s t r a t i g r a p h y , and (3) f e a t u r e s  119  c a n be  earlier  reconstructed  ore horizon  that  of the s t r a t i f o r m  layer  are c o n s i s t e n t with  volcanogenic the  origin  conformity  lateral  stratiform  origin.  versus  mineral  footwall contact relationships,  compositions  of the s u l f i d e s  barite,  gangue, and t h e J u r a s s i c of the D o l l y  Recognition  "fingerprint"  Varden  Dolly  probable the  especially  extensions  related  genesis,  will  they  Three of these  orebodies are  host  significant  the f o l l o w i n g  blocks, Dolly  have been mined.  the South Musketeer  particularly  Several  Varden other  and K i t s o l , a r e  layer.  northward,  Continuation of is likely.  Mineral  t o b a s i n c o n f i g u r a t i o n and o r e c o n t r o l s i n i t s  was a n o t h e r  volcanogenic  because of  Varden East, N o r t h s t a r ,  of the s t r a t i f o r m  known o r e z o n e s ,  zoning,  here  V a r d e n West, D o l l y  N o r t h s t a r and T o r b r i t ,  prospects,  importance  So f a r , f i v e  ore  East,  character of  blocks hosting stratiform  sets of f a u l t s .  and Moose-Lamb.  carbonate  The most i m p o r t a n t o f  b l o c k s have been i d e n t i f i e d ;  Torbrit,  and  and v o l c a n o g e n i c  structural zones:  quartz  f o r the lead-bearing  exploration implications.  by two m a j o r  isotopic  camp.  of the s t r a t i f o r m  i s that s t r u c t u r a l  confined  versus  Varden d e p o s i t s i s of s p e c i a l  positive  these  fragments of  ore within tuffaceous v o l c a n i c rocks of the i n the stable  its  includes:  zonation patterns, consistent  consistent differences  the D o l l y  fora  of layered m i n e r a l i z a t i o n with s t r a t i g r a p h y ,  hangingwall,  deposits  Evidence  f o r t h e main m i n e r a l o c c u r r e n c e s  and v e r t i c a l  hangingwall  a volcanogenic  nature  key f a c t o r of these  undoubtedly  benefit  i n the r e c o g n i t i o n of the  deposits. the search  120  The s e t t i n g u n r a v e l l e d f o r extensions  o f known  ore  deposits  deposits  i n t h e camp; i t may a l s o h e l p  elsewhere  i n Hazelton  Group r o c k s  focus  e x p l o r a t i o n on  i n western  British  Columbia.  In  summary, g e o l o g i c a l m a p p i n g , c o m b i n e d w i t h  petrographic  and i s o t o p i c d a t a ,  silver-lead-zinc-barite probably Early the  indicate that  m i n e r a l i z a t i o n i n the D o l l y Varden  Group.  This  deposits,  features  not g e n e r a l l y  marginal  zonation  found  represents  large basin,  horizon features oxide and  that  shallowing  over  i s the well  facies.  away from  3km a c r o s s ,  s u l f i d e minerals  feature  massive s u l f i d e s ,  should  through  probably  the e x h a l a t i v e  vent.  stratiform  exceptional  The p r e p o n d e r a n c e o f  i n the ore, also  to classify  b e c a u s e by d e f i n i t i o n ,  of these deposits  sulfide,  the d e p o s i t i o n a l basin  a l s o makes i t d i f f i c u l t  of unique  developed  This  i t , are other  i s unique  i s shallow.  these  deposits  the s t r a t i f o r m  be composed o f a t l e a s t  121  The  deposits.  and t h e e x t e n s i v e  of the D o l l y Varden d e p o s i t s . over  to the  deposits.  volcanogenic  from t h e i n n e r  oxide  accumulated w i t h i n  minerals  portion  features  to outer  possibly indicates that  This as  a basin  belong  massive s u l f i d e  i n other  of ore f a c i e s ,  carbonate,  of  volcanic-hosted,  however, d i s p l a y a c o m b i n a t i o n  One o f t h e most o u t s t a n d i n g lateral  f o r other  and t h e r e f o r e  worldwide c l a s s of volcanogenic Varden d e p o s i t s ,  with  geological setting forstratiform  i s s i m i l a r to that  submarine e x h a l a t i v e  camp  associated  to Middle J u r a s s i c c a l c - a l k a l i n e a n d e s i t i c volcanism  mineralization  The  the s t r a t i f o r m  f o r m e d as s u b m a r i n e e x h a l a t i v e d e p o s i t s  Hazelton  Dolly  petrologic,  60  percent et  sulfide  a l . , 1981).  minerals  with  Extraordinary the  lesser  silver  comprised  setting,  The  grades represent High  unique  feature of  g r a d e s and many o f t h e described  t o i t s unique, a n d e s i t i c t e c t o n o s t r a t i g r a p h i c  combination  of a l l of the above-mentioned  to pigeonhole  the s t r a t i f o r m  established  generalized volcanogenic  Varden d e p o s i t s  classification  deposit  type".  type  This  oxide  f e a t u r e s makes  silver-lead-  o f t h e D o l l y V a r d e n camp i n t o any model.  Therefore, the  possibly display criteria for  o f a new, p r e v i o u s l y u n r e c o g n i z e d ,  volcanogenic  volcanic  q u a r t z and  D o l l y Varden ores  deposits  high  another  silver  zinc-barite  and  of mainly  with  and t o i t s d e p o s i t i o n a l t e m p e r a t u r e .  difficult  Dolly  sulfide minerals,  camp,  h e m a t i t e and m a g n e t i t e .  features of the s t r a t i f o r m  a b o v e , may r e l a t e  1976 i n F r a n k l i n  i n the D o l l y Varden  15 p e r c e n t  barite,  D o l l y V a r d e n camp o r e s .  other  it  about  remainder of the h o r i z o n  carbonate,  and S c o t t ,  Stratiform deposits  however, a v e r a g e o n l y the  (Sangster  type  that  is identified  as " D o l l y V a r d e n  i s c h a r a c t e r i z e d by s i l v e r - r i c h ,  stratiform  deposits enclosed  rocks.  122  s t r a t i f o r m and  low s u l f i d e  i n andesitic  BIBLIOGRAPHY A l l d r i c k . , D.J., Dawson, G.L., B o s h e r , J.A., and W e b s t e r , I . 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J . , H o l l a n d , H.D., Clark, B.C., P i s u t h a - A r n o n d , V., E l d r i d g e , C.S., and Ohmoto, H., 1981, The m i n e r a l o g y and t h e i s o t o p i c c o m p o s i t i o n o f s u l f u r i n h y d r o t h e r m a l s u l f i d e / s u l f a t e d e p o s i t s on t h e E a s t P a c i f i c R i s e , 21oN l a t i t u d e : E a r t h P l a n e t . S c i . L e t t e r s , v . 53, p. 382-390. T a y l o r , H.P., 1979, Oxygen and h y d r o g e n i s o t o p e r e l a t i o n s h i p s i n h y d r o t h e r m a l m i n e r a l d e p o s i t s , i n B a r n e s , H.L. e d . , G e o c h e m i s t r y o f h y d r o t h e r m a l o r e d e p o s i t s , 2nd E d : New Y o r k , J o h n W i l e y and S o n s , p. 236-277. T a y l o r , S.R., 1968, G e o c h e m i s t r y o f e d . , O r i g i n and d i s t r i b u t i o n o f P r e s s , p. 559-583.  a n d e s i t e s , i n Ahrens, the e l e m e n t s : O x f o r d ,  L.H., Pergamon  , 1969, T r a c e e l e m e n t c h e m i s t r y o f a n d e s i t e s and a s s o c i a t e d c a l c - a l k a l i n e r o c k s , in M c B i r n e y , A., ed., P r o c e e d i n g s from the a n d e s i t e c o n f e r e n c e : Oregon Dept. G e o l . M i n e r a l I n d u s t r i e s B u l l . 65, p. 43-63. T h i e r s c h , P., 1986, The g e o l o g y o f t h e W o l f s i l v e r prospect, upper K i t s a u l t v a l l e y , B r i t i s h C o l u m b i a : Unpublished B.Sc. t h e s i s , The U n i v e r s i t y o f B r i t i s h C o l u m b i a , 45p. 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G e o l o g y , v . 20, p. 325-343.  130  APPENDIX J STABLE ISOTOPE FRACTIONATION EQUATIONS uxygen (250 to 500oC)  103lnc< = 3.34(106/T2)  -  3.31  r e f . Matsuhisa et a l . , 1979  2.  Barite-Water (110 to 350oC)  103ln « = 3.01(106/T2)  -  7.30  r e f . Kusakabe and Robinson, 1977  3.  Calcite-Water  103ln <* = 2.78(10B/T2)  -  2.B9  r e f . Friedman and O'Neil, 1977  4.  Witherite-Water (0 to 500oC)  103lnc< = 2.57(10B/T2)  -  4.23  r e f . Friedman and O'Neil, 1977  5.  Quartz-Barite  103ln<< = 0.33(10B/T2) + 3.99  6.  Quartz-Calcite  103lnoC = D.56(106/T2)  0.42  determined by subtracting (3) from (1) above  7.  Quartz-Witherite  103lnoc = 0.77(106/T2) + 0.92  determined by subtracting (4) from (1) above  8.  Calcite-Witherite  103ln oc = 0.21(106/T2) + 1.34  determined by subtracting (4) from (3) above  103lnoc = 0.72(10B/T2)  r e f . Ohmoto and Rye, 1979  Pyrite-Galena  1D3lnoC = 1.02(10B/T2)  r e f . Ohmoto and Rye, 1979  11. Pyrite-Sphalerite  103ln <* = 0.30(10B/T2)  r e f . Ohmoto and Rye, 1979  12. Sulfates-Pyrite  103lnc< = 4.67(106/T2) + 6.00  r e f . Ohmoto and Rye, 1979  13. Sul fates-Galena  103ln oC = 3.65(106/T2) + 6.00  determined by subtracting (10) from (12) aboi  14. Sul fates-Sphalerite  103lnoC = 4.37(106/T2) + 6.00  determined by subtracting (11) from (12) abo\  1 . Quartz-Water  (0 to 500oC)  -  determined by subtracting (2) from (1) above  Sulfur 9. 10.  Sphalerite-Galena  

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