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Galena lead isotope study of mineral deposits in the Eagle Bay Formation, southeastern British Columbia Goutier, Françoise Mélanie 1986

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GALENA LEAD ISOTOPE STUDY OF MINERAL DEPOSITS IN THE EAGLE BAY FORMATION,  SOUTHEASTERN BRITISH COLUMBIA  by  FRANCOISE MELANIE GOUTIER B.Sc  UNIVERSITE DE MONTREAL, 1982  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE  REQUIREMENTS FOR THE DEGREE OF MASTERS OF SCIENCE in  THE  FACULTY OF GRADUATE STUDIES  DEPARTMENT OF GEOLOGICAL SCIENCES  We a c c e p t  this  thesis  to the r e q u i r e d  THE  as c o n f o r m i n g standard  UNIVERSITY OF BRITISH  COLUMBIA  OCTOBER, 1986  @ Francoise  Melanie  G o u t i e r , 1986  In  presenting  degree  at  this  the  thesis  in  University of  partial  fulfilment  of  this  department  or  publication  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. 1 further copying of  the  is  granted  by the  understood  that  head of copying  my or  be allowed without my written  ABSTRACT  The area,  Eagle  Bay F o r m a t i o n  i n t h e Adams  35km n o r t h e a s t o f Kamloops, h o s t s  sub-economic m i n e r a l i z e d o c c u r r e n c e s . these  Plateau-Clearwater  s e v e r a l e c o n o m i c and The age and g e n e s i s o f  m i n e r a l d e p o s i t s c a n be e s t i m a t e d  by u s i n g a  specific  growth c u r v e w h i c h d e p i c t s t h e l e a d e v o l u t i o n f o r t h e E a g l e Bay Formation. local  This curve,  d e v i a t i o n from  Sinclair  the average  T h i s remodeled curve  Adams P l a t e a u - C l e a r w a t e r  the d e p o s i t s of the E a g l e clusters signature  'shale' curve  represents a  o f Godwin and  (1982) f o r t h e a u t o c h t h o n o u s p a r t o f t h e C a n a d i a n  Cordillera. the  named t h e r e m o d e l e d c u r v e ,  along  the curve  of the Eagle  is specifically  area.  The l e a d  Bay F o r m a t i o n indicating  i s o t o p e data  plot  i n three  t h a t the l e a d  Bay F o r m a t i o n  applicable to  i s upper  from  distinct  isotopic  crustal,  and t h a t  t h r e e p e r i o d s o f m i n e r a l i z a t i o n c a n be r e c o g n i z e d o r 'fingerprinted'.  Accordingly, m i n e r a l i z a t i o n oogenetic  Devonian volcanism, can  related  be d i s t i n g u i s h e d by l o c a t i o n  within  clusters  Triassic and  and v e i n s  pulse  stratiform  or o o g e n e t i c  raises  of g a l e n a - l e a d  1 or 3 r e s p e c t i v e l y .  magmatism  isotope  Cluster 2 reflects  values a Late  o f m i n e r a l i z a t i o n and i n c l u d e s e p i g e n e t i c v e i n s deposits.  with  mineralization  to Cretaceous  with  their  These d e p o s i t s a r e e i t h e r host.  The T r i a s s i c  that i s apparently  questions  stratiform  about t h e c u r r e n t l y  replacement  model age f o r and o o g e n e t i c  a s s i g n e d C a m b r i a n age o f  associated new is  Upper  host  rock.  Triassic  To accommodate  unit  the l e a d i s o t o p e data  (T-EBG) w i t h i n t h e E a g l e  Bay  a  Formation  defined.  The d i s t i n c t i v e hosted  by t h e E a g l e  future mineral Clearwater  practical  Bay F o r m a t i o n  s i g n a t u r e between  i s v a l u a b l e as a g u i d e f o r  types  Recognition of m i n e r a l  of l e a d i s o t o p i c deposits, provides  framework f o r t h e c l a s s i f i c a t i o n  mineralized  deposits  e x p l o r a t i o n programs i n t h e Adams P l a t e a u -  area.  fingerprint  lead isotopic  prospects  i n the a r e a .  iii  fields  that  a u s e f u l and  and e v a l u a t i o n o f  new  Table of Contents  ABSTRACT  i i  L I S T OF TABLES  v i i  L I S T OF FIGURES  viii  ACKNOWLEDGMENTS  ix  1.  GENERAL  1  2.  GENERAL GEOLOGY OF THE ADAMS PLATEAUCLEARWATER AREA  4  2.1  INTRODUCTION  4  2.2  STRATIGRAPHY  9  2.3  INTRUSIONS  2.4  3.  INTRODUCTION  13  2.3.1  DEVONIAN  INTRUSIONS  2.3.2  CRETACEOUS  2.3.3  LAMPROPHYRE DYKES  INTRUSIONS  .  13 14 17  STRUCTURE  17  2.4.1  PRE-JURASSIC STRUCTURES  18  2.4.2  JURASSIC STRUCTURES  18  2.4.3  CRETACEOUS  19  2.4.4  TERTIARY STRUCTURES  STRUCTURES  20  LEAD ISOTOPE SYSTEMATICS  22  3.1  HISTORY OF LEAD ISOTOPE INTERPRETATION  22  3.2  BASIC PRINCIPLES AND EQUATIONS  26  3.3  ANALYTICAL PROCEDURES  31  iv  3.3.1  SAMPLE DESCRIPTION  31  3.3.2  ANALYTICAL PRECISION  31  3.3.3  CALCULATION OF AVERAGE VALUES  FOR  THE DEPOSITS 3.4  34  THE REMODELED CURVE FOR THE EAGLE BAY FORMATION 3.4.1  3.5 4.  39  DEPARTURE T I M E ,  INITIAL  COMPOSITION  AND U VALUE  47  3.4.2  W VALUE  51  3.4.3  SUMMARY  52  MODEL AGE DETERMINATION  LEAD ISOTOPES,  53  MINERAL DEPOSITS AND  STRATIGRAPHY  .-  55  4.1  INTRODUCTION  4.2  CLUSTER  4.3  LEAD DATA BETWEEN CLUSTER  4.4  CLUSTER  1:  2:  55  DEVONIAN COGENETIC  DEPOSITS  1 & 2  TRIASSIC STRATIFORM  58 63  AND VEIN  DEPOSITS  64  4.4.1  DEPOSITS GEOLOGY  64  4.4.2  MULTIPLE  4.4.3  INTERPRETATION  OF  LEAD DATA  70  SUMMARY  80  4.5  LEAD DATA BETWEEN CLUSTER  4.6  CLUSTER  3:  CRETACEOUS  2 & 3  VEINS  v  80 83  5.  4.7  LEAD DATA BEYOND CLUSTER 3  87  4.8  SUMMARY  88  CONCLUSIONS  90  REFERENCES CITED  93  APPENDIX A  103  APPENDIX B  147  APPENDIX C  149  v i  L I S T OF TABLES  TABLE 3.0 E q u a t i o n s calculation  used  i n lead  isotopic  model 28  TABLE 3.1 S t a t i s t i c s r e l a t e d t o t h e c a l c u l a t i o n o f mass f r a c t i o n a t i o n f a c t o r s u s i n g B r o k e n H i l l S t a n d a r d (BHS:UBC1)  33  TABLE 3.2 R e p r e s e n t a t i v e lead i s o t o p i c values  35  calculation f o r a given  of average deposit  TABLE 3.3 A v e r a g e g a l e n a l e a d i s o t o p e v a l u e s d e p o s i t s i n t h e E a g l e Bay F o r m a t i o n  TABLE 3.4 L e a d i s o t o p e shale curve  values  galena  f o r ore 37  f o r the remodeled 48  TABLE 4.0 C l a s s i f i c a t i o n and name o f d e p o s i t s w i t h i n d i s c r e t e c l u s t e r s of data d e f i n e d i n F i g u r e s 3.3 t o 3.5  TABLE A . l M i n e r a l d e p o s i t s i n t h e Adams area d e s c r i b e d i n appendix A  vi i  56  Plateau 104  L I S T OF FIGURES FIGURE 1.0 G e n e r a l i z e d t e c t o n i c Cordillera FIGURE 2.0 R e g i o n a l Clearwater area  map  of the Canadian 2  g e o l o g i c map  o f t h e Adams P l a t e a u 5  FIGURE 2.1 G e o l o g y o f t h e E a g l e major r o c k u n i t s and f a u l t s  Bay F o r m a t i o n  showing 10  FIGURE 3.0 Model e v o l u t i o n o f l e a d w i t h t i m e . A: D i a g r a m 2 0 7 p b / 2 0 4 p v s . 206pb/204pb B: D i a g r a m 208pb/204pb v s . 206pb/204pb D  FIGURE 3.1 S c h e m a t i c e v o l u t i o n o f t h e l e a d t h e E a g l e Bay F o r m a t i o n  i n galena  23 from 29  FIGURE 3.2 207pb/204pb v s . 206pb/204pb d i a g r a m showing t h e i s o t o p i c d i s t r i b u t i o n o f a l l a n a l y s e s from t h e B i r k Creek area  36  FIGURE 3.3 207pb/204pb v s . 206pb/204pb d i a g r a m f o r d e p o s i t s h o s t e d by t h e E a g l e Bay F o r m a t i o n u s i n g from T a b l e 3.3  data 41  FIGURE 3.4 208pb/204pb v s . 206pb/204pb d i a g r a m f o r d e p o s i t s h o s t e d by t h e E a g l e Bay F o r m a t i o n u s i n g from T a b l e 3.3  data  FIGURE 3.5 206pb/208pb v s . 206pb/207pb d i a g r a m f o r d e p o s i t s h o s t e d by t h e E a g l e Bay F o r m a t i o n u s i n g from T a b l e 3.3  data  FIGURE 4.0 G e o l o g y location  of the Eagle  Bay F o r m a t i o n  43  with  o f t h e sampled m i n e r a l d e p o s i t s  FIGURE 4.1  Folded mineralized layers,  FIGURE A.1  Map  45  59  L u c k y Coon d e p o s i t  o f t h e Homestake p r o p e r t y  67 121  FIGURE A.2 Lower h e m i s p h e r e e q u a l a r e a p r o j e c t i o n of s t r u c t u r a l e l e m e n t s , Homestake d e p o s i t a r e a FIGURE A.3 V e r t i c a l s e c t i o n (97+00) t h r o u g h t h e RG 8 s u l p h i d e b a r i t e l e n s , Rea G o l d d e p o s i t  126  FIGURE A.4 E q u a l a r e a p r o j e c t i o n s o n t o lower of s t r u c t u r a l e l e m e n t s Rea G o l d d e p o s i t  128  FIGURE A.5 D e t a i l e d s e c t i o n s A-A n o r t h s i d e of B i r k C r e e k a r e a 1  and B-B'  v n i  123  hemisphere  from t h e 131  ACKNOWLEDGEMENTS  I acknowledge the B r i t i s h M i n e s and P e t r o l e u m R e s o u r c e s work.  Many from  grateful his  encouragement  forfinancial  attitude,  and c r i t i c a l  my t h i n k i n g t h r o u g h o u t  this  hisdirection,  and  t o D r . R.L. A r m s t r o n g  f o r p r o v i d i n g access  t o thank a l l s t u d e n t s ,  their  D r . C . I . Godwin  e n c o u r a g e m e n t and s u p e r v i s i o n o f my  Columbia.  by  t o work, f o r  and t o P a u l  t o my a d v i s o r  Laboratory  members  particularly  d i s c u s s i o n s which i n f l u e n c e d  Geochronological I wish  I am  of f i e l d  research.  thanks a r e extended  for  support  whom i t was a p l e a s u r e  and s u p p o r t i v e  f o r ideas  Sincere  M i n i s t r y of Energy,  t h e M i n i s t r y were h e l p f u l .  t o T r y g v e Hoy, w i t h  Schiarizza  Columbia  i n t h e department  thesis,  to h i s  a t The U n i v e r s i t y o f B r i t i s h faculty  and s t a f f  of G e o l o g i c a l Sciences  who c o n t r i b u t e d  knowledge and f r i e n d s h i p t o t h e c o m p l e t i o n  of t h i s  thesis.  I a l s o thank A l e x Falconbridge Co. of  Copper and G l e n  Ltd. fortheir this  they  me.  are greatly  of Corporation  Shevchenko o f Noranda E x p l o r a t i o n  availability  p r o j e c t with  provided  D a v i d s o n and I a n P i r i e  and f o r d i s c u s s i n g some  The i n f o r m a t i o n and g a l e n a appreciated.  ix  aspects  samples  1  1. GENERAL  The area,  INTRODUCTION  Eagle  centred  Columbia  Bay F o r m a t i o n  i s i n t h e Adams  Plateau-Clearwater  35km n o r t h e a s t o f Kamloops i n s o u t h e a s t e r n  ( F i g . 1.0).  The f o r m a t i o n  is a  multiply-deformed  s e q u e n c e o f l o w - g r a d e m e t a - s e d i m e n t s and v o l c a n i c r o c k s as  imbricated s l i c e s  on t h e s o u t h w e s t e r n  M e t a m o r p h i c Complex.  I t hosts  lead-zinc-silver-gold  occurrences  first  of the c e n t u r y .  Gold  type by  o f t h e Shuswap  o f v a r i o u s t y p e s and  t h a t were i n t e r m i t e n t l y  Rea  flank  i n p r o d u c t i o n d u r i n g the  Recent d i s c o v e r y of the p o l y m e t a l l i c  deposit, a g o l d - a r s e n o p y r i t e - r i c hvolcanogenic  d e p o s i t near  Johnson Lake, r e g e n e r a t e d  p r o v i d i n g evidence  stacked  s e v e r a l e c o n o m i c and s u b - e c o n o m i c  affinities half  British  of p o t e n t i a l l y  interest  significant  Kuroko  i n the a r e a  economic  mineralization.  This isotope of  thesis  t o a s s e s s whether  s t u d i e s would a i d i n t e r p r e t a t i o n s  the d i f f e r e n t  Formation. useful  was i n i t i a t e d  of the nature  I t also  Plateau-Clearwater  and age  was i n t e n d e d  t o p r o v i d e a p r a c t i c a l and  area.  Observations  i n t h e Adams  (and i n some  cases  mapping) were made on 37 m i n e r a l i z e d o c c u r r e n c e s  were sampled conducted  lead  d e p o s i t s o c c u r r i n g w i t h i n t h e E a g l e Bay  framework f o r g u i d i n g e x p l o r a t i o n programs  detailed  galena  for this  over  study  (Appendix  A).  Field  t h e summers o f 1984 and 1985.  which  work was  Remains  from  past  2  F i g u r e 1.0. G e n e r a l i z e d t e c t o n i c map o f t h e C a n a d i a n C o r d i l l e r a showing t h e major s t r u c t u r a l d i v i s i o n s and l o c a t i o n of t h e s t u d y a r e a ( a f t e r Wheeler and G a b r i e s l e , 1972).  3  mining  activities  access  t o the v i s i t e d p r o p e r t i e s .  The geology second the  first  and l o g g i n g r o a d s  p a r t of t h i s  of the Eagle part outlines  common  study  Bay F o r m a t i o n  i n the area  presents  an o v e r v i e w  and o f a d j a c e n t  the b a s i c p r i n c i p l e s  l e a d method  facilitated  of the  a r e a s . The  which govern  f o r model age d e t e r m i n a t i o n s .  uses o f A  r e m o d e l e d v e r s i o n o f t h e ' s h a l e ' growth c u r v e  o f Godwin and  Sinclair  (1982) i s u s e d  isotopic  deposits  hosted  this  thesis  defined of  to interpret  by t h e E a g l e  interprets  Bay F o r m a t i o n .  galena  into  three d i s t i n c t  mid-Cretaceous) are presented. l e a d model age o b t a i n e d their  geological  interpretation replacement  Triassic  understanding  p a r t of  groups  (Devonian,  T r i a s s i c and  The d i s c r e p a n c y between  Triassic  d e p o s i t s and  i s d i s c u s s e d , and l e a d s t o t h e  t h a t i f the m i n e r a l i z a t i o n i s not of T r i a s s i c but r a t h e r o o g e n e t i c  of the Eagle  unit.  from  Implications of the c l u s t e r i n g  for several stratiform  setting  type,  stratigraphy  The t h i r d  data  l e a d model ages o f d e p o s i t s  by t h e r e m o d e l e d c u r v e .  the data  the lead  Bay F o r m a t i o n  The r e s u l t s and t o m i n e r a l  Plateau-Clearwater  area.  with  i t s host  should  a r e fundamental  then the  include a  to geological  e x p l o r a t i o n i n t h e Adams  4  2. GENERAL GEOLOGY OF  2.1  THE  ADAMS PLATEAU-CLEARWATER AREA  INTRODUCTION  M i n e r a l d e p o s i t s and  occurrences  i n t h e Adams P l a t e a u -  C l e a r w a t e r a r e a a r e h o s t e d by t h e E a g l e Bay F o r m a t i o n , w h i c h i s composed of a m u l t i p l y d e f o r m e d s e q u e n c e o f l o w - g r a d e sediments  and  volcanic rocks.  The  E a g l e Bay  w i t h i n Kootenay Terrane  ( M o n g e r , 1985)  o f t h e Monashee T e r r a n e  i n t h e Omineca B e l t  E a g l e Bay  Formation  ( S c h i a r i z z a and thesis  ranges  i n age  P r e t o , 1984).  1984).  ( F i g . 2.0).  flank The  Permian  be as young as Upper  the N o r t h w e s t e r n  Triassic.  east of the Eagle  Shuswap Complex  Bay  (Okulitch,  T h i s c o m p l e x , a l o n g w i t h t h e Monashee C o m p l e x (Read  B r o w n , 1981)  and  Shuswap M e t a m o r p h i c C o m p l e x t h a t c u r r e n t l y  i n c l u d e d i n Monashee T e r r a n e  b e t w e e n t h e E a g l e Bay C o m p l e x now  and  t h e Okanagan P l u t o n i c and M e t a m o r p h i c C o m p l e x ,  i s p a r t of the l a r g e r is  lies  a l o n g the western  from Cambrian t o  Much o f t h e a r e a a d j a c e n t t o and is called  Formation  However, as d e f i n e d i n t h i s  i t c o n t a i n s r o c k s t h a t may  Formation  meta-  Formation  (Monger, 1985). and  The  the Northwestern  boundary Shuswap  i s r e c o g n i z e d t o be a low a n g l e d e t a c h m e n t  fault  r a t h e r than a metamorphic or i n t r u s i v e c o n t a c t ( B r o c k ,  1934;  Fyson,  1970).  This f a u l t ,  named t h e E a g l e R i v e r f a u l t  i n recent  5  F i g u r e 2.0 Regional g e o l o g i c map of the Adams PlateauClearwater area showing the l o c a t i o n of the Eagle Bay Formation r e l a t i v e to other major formations and groups, majors i n t r u s i o n s , and r e g i o n a l y important f a u l t s (modified: from O k u l i t c h and Cameron, 1976; Journeay, 1986; Jung, 1986).  6  LEGEND Jurassic  I***;*)  &  Cretaceous  Granitic rocks  Upper Triassic | NCL |  Undiff. Nicola Group rocks  Upper Triassic and older Eagle Bay Formation 1 FNL |  Fennell Formation  Undetermined age j Und  Sicamous Formation Undiff. Paleozoic rocks Undiff. Paleoz. intrusives  SYMBOLS High angle faults Eagle River Detachment Quesnel Lake thrust 0.7060 initial Sr/ Sr ratio, isotopic contour line 8 7  8 6  7  mapping  (Journeay,  break-away 1986)  zone  south-central Coney,  1980;  F i g . 2.0), i s interpreted  i s part  o f t h e major e x t e n s i o n a l  t o t h e Eocene British  thermal event  Columbia  F o r m a t i o n of the S l i d e  Tipper,  1971).  The F e n n e l l  a s s e m b l a g e of p i l l o w e d  Preto, fault  1922).  These  directed  (Okulitch, 4.4.3).  1974;  two  thrust  with  Bardoux,  1984;  M o u n t a i n Group  diorite  formations fault  ( C a m p b e l l and o f an  (Okulitch,  Triassic(?)  1979;  formation  (Fig.  i s truncated  oceanic  cherts  are separated  by an  Schiarizza  i s inferred  and  t o be i n  Sicamous F o r m a t i o n  to the north  section  by the R a f t  2.0).  (Monger,  1986)  i s exposed i n a s e r i e s of  domal  metamorphic  complexes. Each i s c h a r a c t e r i z e d  older  metamorphic  plutonic  covered  Parkinson,  and r i b b o n  the f o r m a t i o n  t h e Upper  Monashee T e r r a n e  is  in  J o u r n e a y , 1986:  1 984 ; D a u g h t r y i n P r e t o e t a_l.,1985; see  The  batholith  identified  F o r m a t i o n i s composed  basalts,  1 9 8 4 ) . To t h e s o u t h contact  fault  Bay F o r m a t i o n i s b o r d e r e d on t h e west by t h e  Fennell  easterly  (Journeay,  1985).  The E a g l e  (Uglow,  (Ross,  T e m p e l m a n - K l u i t , 1984;  Parrish,  as t h e  f o r t h e s o u t h e r n Okanagan d e t a c h m e n t  and t h e r e f o r e  system r e l a t e d  1985;  1986;  basement,  which e i t h e r  by p o l y d e f o r m e d and r e g i o n a l l y  s e q u e n c e s o f s e d i m e n t a r y and v o l c a n i c  by a c o r e o f crops out or  metamorphosed  rocks  (Brown and  mixed Read,  8  1983;  Coney,  1980).  from p o s s i b l y Okulitch, the c o r e  Rocks w i t h i n  Archean t o e a r l i e s t  1984).  zone o f t h e C o l u m b i a n Orogeny  i n t h e Omineca  during  Jurassic  time  lacking,  although  previous  Kootenay  (Duncan, 1982; i s r e g a r d e d as  w h i c h c a u s e d major  and Moore,  1970; O k u l i t c h ,  deformation  some o f t h e s t r u c t u r e s may have been  (Okulitch,  1979).  o f a major Eocene  i s primarily  tectonics,  rather  Brown and Read Formations, have been  t h e r m a l and e x t e n s i o n a l  their  Thus, t h e E a g l e  as t h e R a f t  Tertiary  core  extensional  Bay and t h e F e n n e l l  and t h e B a l d y  above t h e Monashee Complex  f o r m a t i o n and would have  (Journeay,  Belts.  of metamorphic  of T e r t i a r y  event  t h a n o f M e s o z o i c c o m p r e s s i o n as s u g g e s t e d by  as w e l l  approximately  1985;  the unroofing  a result  (1983).  located  generated  s u c h as K e n o r a n , t h e H u d s o n i a n , o r t h e  (1985) a r g u e s t h a t  complexes  1984).  i n the b e l t i s  w i d e s p r e a d t h r o u g h o u t t h e I n t e r m o n t a n e and Omineca  Parrish  defor-  i n t h e E a g l e Bay F o r m a t i o n —  for pre-Jurassic  orogenies  Evidence is  Belt—and (Reesor  Unambiguous e v i d e n c e  East  Jurassic  The Shuswap M e t a m o r p h i c Complex  mation  in  t h e c o m p l e x e s r a n g e i n age  50Ma ago.  slid  batholiths,  a t the time o f  o f f the metamorphic  The E a g l e R i v e r  would  detachment  complex  fault  zone  1986; F i g . 2 . 0 ) , and numerous n o r m a l f a u l t s o f  age and r e l a t e d  Hickson,  Tertiary  1986) a r e a l s o  and d e f o r m a t i o n a l  event.  volcanic  attributed  rocks  (Schiarizza,  t o t h e Eocene  However p r o b l e m s a r i s e  thermal  when t h e  9  initial are  87sr/86sr  taken  present,  of  r a n g i n g from that  t h e R a f t and  batholiths that  that  correspond  are  expected  the present to their  i t i s improbable  interpretation  of t h e b a t h o l i t h s  those  t h e Monashee Complex d u r i n g  (1986) a r g u e s  and  batholiths  c o n s i d e r a b l y h i g h e r than  the Monashee Complex.  agreement w i t h t h e  roots  that  from  their position  original they  ever  T h i s argument i s a l s o  of O k u l i t c h  i n the Northwestern  (1979) t h a t Shuswap  the  Complex.  STRATIGRAPHY  The as  through  Baldy  over  the Baldy  0.7083 t o 0.7101, a r e t o be  position,  were l o c a t e d  2.2  pass  Values  T h e r e f o r e , Jung  emplacement  in  o f t h e R a f t and  i n t o account.  intrusions ascent.  ratios  E a g l e Bay  Formation  t h e Adams L a k e and  (1915) d i v i d e d  Nisconlith  first  mapped by Dawson  Series.  Subsequently  t h e Adams Lake S e r i e s  formations  called  limestone,  and  Jones  was  into  R i c e and  the T s h i n a k i n Jones  (1959) renamed many o f t h e r o c k s p r e v i o u s l y  t h e above s e r i e s ,  and  Formation  The  formation then  Lake S e r i e s  and  Daly's  three  members: a t h i c k  mixed  sedimentary  (1948)  was  the youngest included  conformable  member.  formation; i t contained  b a s a l s u c c e s s i o n of c h l o r i t i c including  which  much o f Dawson's Adams  (1915) g r e e n s t o n e  sequence  and  included i n  d e f i n e d t h e Mount I d a Group w i t h i n  t h e E a g l e Bay E a g l e Bay  Daly  three informal  the Adams Lake g r e e n s t o n e ,  the B a s t i o n s c h i s t s .  (1898)  the prominent  schist,  Tshinakin  a  1 0  D e v o n i a n to Fennell [ b H  I  Permian  1 1  Formation Upper structural division: pillowed and massive m e t a - b a s a l t , minor chert  IF I  Lower structural division: pillowed and massive meta-basalt  and ribbon chert, limestone,  gabbro, quartzteldspar, porphyry,  diorite,  rhyolite  Mississippian I E8P I  P h y l l i t e a n d s l a t e with i n t e r b e d d e d s a n d s t o n e a n d grits  Devonian a n d / o r Mississippian I EBF |  F e l d s p a t h i c p h y l l i t e ( i n t e r m e d i a t e to f e l s i c t u f t )  Devonian | EB.A |  S e r i c i t e - q u a r t z - p h y l l i t e a n d s c h i s t ( i n t e r m e d i a t e to felsic volcanics and v o l c a n o c l a s t i c s )  Devonian and/or  older  | EBS j  Mixed meta-sedimentary  sequence  | EBG [  C a l c a r e o u s chlorite-schist. fragmental (matic to i n t e r m e d i a t e v o l c a n i c s )  schist  Tshinakin limestone  ]j ^--^  mixed phyllite  f—*-j  quartzite  f  |  polymictic conglomerate (EBCcg)  |  |  T-EBC ( ? T r i a s s i c )  Lower  (phyllites)  Cambrian  (EBCp)  ( EBCq )  and/or  older  I EBQ |  C h l o r i t e - m u s c o v i t e quartzite. c h l o r i t e - m u s c o v i t e - q u a r t z schist and minor m e t a - s e d i m e n t s (SDQl  I EBH |  Quartzite, grit and c h l o r i t e - s e r i c i t e - q u a r t z  schist  Intrusives Jurassic E;;:' ;l Late  1  2  3  k,  Granite and granodiorite o r t h o g n e i s s  Fossil locality: M i s s i s s i p p i a n . Pennsylvanian, Permian  f r  Raft batholith. Baldy batholith, Scotch Creek plug  Devonian  | Dgn I '  & Cretaceous  Cambrian z. Rb  Isotopic date: K / A r , u r a n i u m - l e a d , R b / S r Faults T h r u s t fault (this  ^M*'  study)  Thrust fault ( S c h l a r l z z a et a l . 1 9 8 4 )  F i g u r e 2.1 G e o l o g y o f t h e E a g l e Bay F o r m a t i o n showing major r o c k u n i t s and f a u l t s ( m o d i f i e d from S c h i a r i z z a and P r e t o , 1984).  12  Limestone, sequent  and  an  work by  upper  s e q u e n c e of c h l o r i t i c  C a m p b e l l and  Schiarizza  and  Schiarizza  (1986, 1986b) r e f i n e d  stratigraphy Fennell  slices  ( F i g . 2.1;  Stratigraphic Schiarizza  deposits  and of  their the  of  Eagle  Bay  Bay  stratigraphic Metamorphic Formation and  Struik  Bay  separated  Formation by  Schiarizza  (1986),  Barkerville  Preto,  lead  the Eagle  the  Formation  composition  interpretation  are presented  is directly  the  correlates  and  the  lithologic, the E a g l e  Kootenay Arc  1986b).  accommodate of  mineral  Formation. from of  these d e p o s i t s , the s t r a t i g r a p h y 4.  with  edge of t h e  other  Shuswap  correlated  the  Cambrian to O r d o v i c i a n Lardeau  younger M i l f o r d on  to  correlative  the  thrust  e s t a b l i s h e d by  i n Chapter  O k u l i t c h (1979) has  with  based  Bay  (1985)  i n four  isotope investigation  isotopic on  adjacent  Schiarizza,  contact relationships  the  lead  the  1984;  and  the  directed  (1984) have been m o d i f i e d  Complex.  similarities,  and  the  i s exposed  southwesterly  s e q u e n c e o c c u r r i n g on  with  of  Schiarizza  Formation  partly  partly  the understanding  P r e t o and  implications  Eagle  (1985),  R e c e n t work by  from  the  Schiarizza  (1979),  and  o c c u r r i n g throughout  Discussion  Okulitch  Formation  Preto  obtained  Sub-  Bay  ages and/or  and  (1971),  P r e t o and  the Eagle  t h a t the E a g l e  imbricated  results  (1984),  of both  Formation.  indicates  faults  Preto  Tipper  schist.  Group,  Group o f t h e K o o t e n a y structural Bay  and  Formation  Terranes.  Arc.  age  with  Similarly,  both Ross  the and  13  Fillipone Formation,  ( i n press) notably  suggest  the b a s a l q u a r t z i t e  meta-volcanic  carbonate  similar  i n the  rocks  t h a t some p a r t s of t h e E a g l e  Snowshoe Group n e a r Struik  in a similar  Accordingly,  Formation  Bay  Kootenay Terrane  under  Lower P a l e o z o i c s t r a t a  comprising  basic  D e v o n i a n and  2.3  acidic  r o c k s and  correlated  Crooked Lake  setting.  i n c l u d e d by  "variably  pellite,  (100km  that a l l three  geological  i s now  Monger  metamorphosed  quartzite,  (?) o l d e r  with  grits,  intrusions."  INTRUSIONS  The  Eagle  Bay  Formation  Magmatism a n d / o r v o l c a n i s m Cretaceous  2.3.1  and  Eocene  Fowler  has  been i n t r u d e d r e p e a t e d l y .  affected  the a r e a  i n Devonian,  time.  Devonian I n t r u s i o n s Meta-biotite  of  prominent  (1986) p r o p o s e d  s u c c e s s i o n s were d e p o s i t e d the E a g l e  the  s u c c e s s i o n , are d i r e c t l y  e a s t of W i l l i a m s L a k e ) .  (1985) i n the  and  Bay  orthogneiss  the Eagle  upper and  lower  D e v o n i a n and Okulitch,  Bay  ( F i g . 2.1),  Formation. intercept  Similar  ranging  Z i r c o n s from  dates  bodies  i n age  with  the  Mount  i n t r u d e s Devonian v o l c a n i c rocks  on  of m i d - C r e t a c e o u s ages  1975).  composition,  granodiorite, correlated  from  of  the b a t h o l i t h  c o n c o r d i a diagrams ( 372+_6Ma and  of  92.5Ma:  intermediate to  Late Devonian to  yielded  felsic  mid-  1 4  Mississippian  (Mortensen et  Snowshoe m e t a - s e d i m e n t s of  these  intrusions  a_l. ,  i n both the  two s u c c e s s i o n s  An e x t r u s i v e found age,  on t h e Beca  type  phase o f  but  upper  oogenetic  and o f  t h e s e v o l c a n i c and i n t r u s i v e western  m a r g i n of  volcanogenic  the  deposits  (e.g.  Shuswap within  dates  felsic  Complex and the  presence  d u r i n g the D e v o n i a n .  Cretaceous The R a f t  intrude  the  localities,  both b a t h o l i t h s  parallel  are  Bay F o r m a t i o n ( F i g .  metamorphic h o r n f e l s i c rotated  of  of (Rea  evidence  for  Intrusions  and B a l d y b a t h o l i t h s  Eagle  suggest  on t h e  the Devonian v o l c a n i c u n i t s  subduction  2.3.2  2.1)  affinities  Appendix A ) , provides  processes  and r o c k  The o c c u r r e n c e  G o l d and Homestake d e p o s i t s , related  diagram  intrusions,  u n i t EBA, F i g .  of  of D e v o n i a n  i n age  felsic  Devonian age.  rocks  between  (meta-rhyolite)  The s i m i l a r i t i e s  the m e t a - v o l c a n i c s  presence the  on a c o n c o r d i a  the  the  areas.  yielded zircon  between t h e Mt F o w l e r o r t h o g n e i s s ,  they are  correlations  composition  intercept  1985).  The  Bay F o r m a t i o n and  support  similar  property also  and S c h i a r i z z a ,  and some of that  Eagle  in regionally distinct  399+^1 Ma, from the  (Preto  occur throughout  i n the B a r k e r v i l l e T e r r a n e .  Snowshoe Group do n o t p r o v e , these  in press),  to  are  aureole  elongated  2.1).  In  bodies  that  several  s u r r o u n d e d by a s t r u c t u r a l i n which r e g i o n a l  t h e westward  t r e n d of  the  structures  intrusions  and are  15  (Campbell  and  Small  T i p p e r , 1971).  intrusive  b o d i e s , such  as t h e S c o t c h C r e e k and  Deep C r e e k p l u t o n s as w e l l as q u a r t z p o r p h y r y occur  throughout  the area  ( F i g . 2.1).  c o g e n e t i c with the Cretaceous  Both  intrusions,  m o n z o n i t e and biotite  as  trations  are  Baldy  similar  chemically.  (Appendix  s e v e r a l molybdenite  Lake a r e a available  Mines and  Cretaceous batholiths mineral an  initial  the western  date  of  obtained initial  occurrences  i n c l u d e the  i n the  provincial  Columbia M i n i s t r y  Rb/Sr d a t e s were o b t a i n e d f o r t h e (1986) w i t h a f i v e  isochron.  open  of  file  Energy,  A mid-Cretaceous of 0.7060 was  f o r the Baldy  initial  p l u s the  date  similarity  of  A  These s i m i l a r  and  104Ma w i t h  o b t a i n e d from  87sr/86sr r a t i o  batholith.  two  p o i n t whole r o c k  p a r t of t h e R a f t b a t h o l i t h .  98.5+2.2Ma w i t h  ratios,  concen-  Resources.  87sr/86sr r a t i o  from  be  q u a r t z v e i n s of t h e Leemac p r o p e r t y  a t the B r i t i s h  by J u n g  separate  intrusions  reported i n unpublished  Petroleum  to  chloritized  Widespread minor  rich  reports  They c o n t a i n  s u l p h i d e m i n e r a l s w i t h i n the  A ) , and  inferred  batholith.  galena-sphalerite  Barriere  They a r e  sills,  are e q u i g r a n u l a r g r a n o d i o r i t e to quartz  the o n l y m a f i c m i n e r a l .  of  dykes or  the  a  sample  mid-Cretaceous o f 0.7054 dates  i n t e x t u r e and  was  and  composition  1  i n d i c a t e  that  Furthermore were  the  Since  t h e  by  a r e  i d - C r e t a c e o u s  Wanless  K - A r dates  b a t h o l i t h s  b a t h o l i t h s  K-Ar m  two  o b t a i n e d  two  e t  a r e  a^L.  concordant  probably  n o t  thermal  e v e n t s .  However,  incomplete  z i r c o n s  from  i t s  a s s i g n e d  comm.,  87sr/86sr  i n i t i a l  Baldy  b a t h o l i t h s  b a t h o l i t h s  l o c a t e d  c o m p a r a t i v e l y the  Shuswap  to  Formation  as  t r a n s i t i o n  shown a t  on  Rb-Sr  b a t h o l i t h .  d a t e s ,  a f f e c t e d  by  new u r a n i u m - l e a d some  82+6Ma  and  Baldy  the  any  data  l a t e r on  u n c e r t a i n t y  c r y s t a l l i z a t i o n  age  r a t i o s  0.7060  basement  b a t h o l i t h s  emphasize  c r u s t a l  The  h i g h from  basement  r a t i o s magma  r o c k s  (Jung,  a  generated the  those  i n  p e r s .  Intermontane  0.7060  a r e  r e p o r t e d  0.7060  passes This  2.0.  t o  (Armstrong,  Eagle  o r  f o r  t h e  the  t h e  contaminated  Bay F o r m a t i o n .  i n  Bay  r e p r e s e n t s  l i m i t  of The  R a f t  and  Baldy  magma  and  the  b a t h o l i t h s a d d i t i o n  V a l u e s  Eagle  1986).  t h e  from  e a s t  probably  J u n g ,  R a f t  i n i t i a l  western  between  these  r e f l e c t i n ,  i n  r a t i o s  l i n k  which  the  the  The  through l i n e  t h e  B e l t .  to  1986).  (Jung,  f o r  0.7040  below  the  g e n e t i c  from  about  i n  87sr/86sr  a p p a r e n t l y  u n d e r l y i n g  than  Complex of  of  c o r r e s p o n d i n g  i n i t i a l  m a t e r i a l  west  F i g u r e  depth  high  o l d  than  r a t i o  r e l a t i v e l y  87sr  the  i n d i c a t e s  higher  the  Metamorphic  i s o t o p e  Precambrian  a r e  g r e a t e r  s t r o n t i u m  a  t h e  s u b s t a n t i a l l y  b a t h o l i t h  m i d - C r e t a c e o u s  w i t h  99+5Ma  of  f o r  o o g e n e t i c .  1 986 ) .  The and  R a f t  dates  ( 1966)  were  the  probably  6  were of  b y , The  d e r i v e d .  r a d i o g e n i c a  Precambrian i n i t i a l  17  strontium  r a t i o s are i n general agreement with the lead i s o t o p i c  s i g n a t u r e of the d e p o s i t s  i n the Eagle Bay  Formation—both  i n d i c a t e the presence of upper c r u s t a l m a t e r i a l beneath the formation.  2.3.3  Lamprophyre Dykes Lamprophyre dykes are widely  Plateau-Clearwater  area, and  d i s t r i b u t e d i n the Adams  commonly are noted on p r o p e r t i e s  where s u l p h i d e m i n e r a l i z a t i o n i s r e p o r t e d  (see d e s c r i p t i o n i n  Appendix A f o r Mosquito King, Crowfoot Mountain, and  Rexspar).  These dykes commonly occur along n o r t h e r l y t r e n d i n g f a u l t s s e v e r a l have y i e l d e d mid-Eocene dates  (dates by the G e o l o g i c a l  Survey of Canada are summarized i n Jung, 1 9 8 6 ) . r e l a t i o n s h i p between these dykes and d i s c u s s e d i n Chapter  2.4  The  sulphide m i n e r a l i z a t i o n i s  4.  STRUCTURE  The  Eagle  Bay  Formation i s complexly deformed.  Timing  r e l a t i o n s h i p s o f t e n are n e i t h e r c l e a r nor c o n s i s t e n t , it  and  i s g e n e r a l l y agreed that a l l the s t r a t i f i e d  although  u n i t s were  deformed (or re-deformed) during the J u r a s s i c f o l d i n g r e l a t e d to the Columbian Orogeny (Campbell, 1973).  event  This  orogeny, a s s o c i a t e d with the a c c r e t i o n of a western allochthonous  terrane a g a i n s t the Omineca b e l t and  (Monger et aJL. , 1 9 8 2 ) ,  the  produced a p e r v a s i v e f o l i a t i o n  craton and  18  southwesterly subsequently folds  2.4.1  to  the  as  as  first  Early  metamorphic isoclinal  was  related  and  1 984) .  Preto,  Jurassic  Later  Formation  northwesterly Raft  and  striking of  the  trending  Baldy  northeasterly  structures  the  to  trending  normal  faults,  formation.  the  is axial 1986).  presence  planar  to  of  very  However, d i r e c t  been masked by  Fennell  directed since  and  the  an  be  as  early  rare,  small  evidence  of  subsequent  thrusts.  E a g l e Bay This  conodont b e a r i n g  because  Structures  by  F o r m a t i o n may  metamorphism.  the  the  E a g l e Bay  indicated  repeated  than J u r a s s i c  structures  2.4.2  of  post mid-Permian,  earlier  and  which  regional  are  the  northerly  e v e n t has  from e a s t e r l y  m i d - P e r m i a n age  as  (Schiarizza,  Juxtaposition resulted  by  d e f o r m a t i o n of  foliation,  and  refolded  E a g l e Bay  Structures  such a d e f o r m a t i o n a l deformation  well  D e v o n i a n as  folds  The  i n t r u s i o n of  major u n i t s  Pre-Jurassic The  faults.  mid-Cretaceous.  faults,  through the  thrust  d e f o r m e d and  i n the  strike-slip  old  was  associated  batholiths  cut  directed  by  the  the  Jurassic  thrusts.  thrusts  are  Formations  thrusting  strata  of  Thrusting folded  C o l u m b i a n Orogeny  event  was  also  by (Schiarizza  19  Units  of  the  E a g l e Bay  syn-metamorphic d e f o r m a t i o n shistosity planar  to  sub-parallel isoclinal  continuity  of  the  transposition (Dickie, Plateau this  folds  o r i g i n a l bedding  s t r i k e due  large  disruptions  westerly  Redistribution  in deposits  of  i n the  King Tut)  and  of  2)  sulphide  lack that  of caused  isoclinal the  trending  related  masses i n  to  to  the  (Appendix  related  folds  Adams  fold  synform area  i s probably  axial  shearing  N i k w i k w a i a L a k e s y n f o r m on  is a  and  to  of  pervasive  v e r g e westward, and  The  L u c k y Coon, E l s i e , (Fig.  along  1)  layering  ( F i g . 2.1)  of  the  by:  evidence  the  deformation.  crests  characterized  folds that  units  of  1985).  to  Formation e x h i b i t  this  A: event  4.1).  A southwesterly present  configuration  panels within thrusting  the  directed of  Eagle  probably  the Bay  thrusting  units  by  Formation  occurred  near the  event  established  creating  major  ( F i g . 2.1). end  of  the  the  imbricated  This Colombian  Orogeny  2.4.3  Cretaceous  Structures  A prominent u p r i g h t , well  exposed  batholiths, intrusions. exposed  i n the  vicinity  is related The  i n the  easterly  best  to  the  of  the  set  of  Raft  the  Baldy  p r e s e n c e of  examples of  Clearwater  oriented and the  folds,  mid-Cretaceous  t h i s phase of  folding  are  a r e a where i n t r u s i o n s  locally  change  20  the p r e d o m i n a n t l y shistosity scale  (Schiarizza,  folds  probably  northerly  dip direction  1986).  o f b e d d i n g and  On t h e Adams P l a t e a u , o u t c r o p  have t h e same e a s t e r l y  orientation;  were g e n e r a t e d d u r i n g o r soon  after  these  folds  the i n t r u s i v e  event.  Northeasterly Barriere Bay  Formation  major of  Lakes  and J o h n s o n  plugs.  strike-slip  Creek  and t h e F e n n e l l  stratigraphic  these  Baldy  trending  faults  fault  were i n t r u d e d  and a c c o u n t  indicating  f o r some  I n the S c o t c h Creek  by C r e t a c e o u s p o r p h y r y  However, i n o t h e r p l a c e s s i m i l a r batholith  such as t h e  ( F i g . 2.1), cut the Eagle  Formation  truncations.  faults,  that  this  faults  faulting  a r e a , some dykes and  extend  i n t o the  i s Cretaceous or  younger.  2.4.4 T e r t i a r y The Eagle  Structures  youngest  phase o f d e f o r m a t i o n , a f f e c t i n g  Bay F o r m a t i o n  and t h e a d j a c e n t F e n n e l l  E o c e n e age and i s c h a r a c t e r i z e d f o l d s with upright responsible  for regional  as t h e f o l d i n g synform.  warping  Bay F o r m a t i o n .  of previous s t r u c t u r e s ,  of t h i s  These  i s of  This deformation i s  surface  of a s e t of normal  Formation,  by o p e n , n o r t h e r l y p l u n g i n g  planes.  of the a x i a l  The o r i e n t a t i o n  orientation Eagle  axial  both the  trace  faults  of the Nikwikwaia  s e t of f o l d s  faults  that  such  i s similar  Lake  to the  c u t a l l u n i t s of the  do n o t c u t t h e o v e r l y i n g  21  Miocene and/or to  basalts;  they l o c a l l y  lamprophyre  the T e r t i a r y  dykes.  extensional  are intruded  These and  structures  by T e r t i a r y  basaltic  probably are  thermal event.  related  22  3.  LEAD ISOTOPE SYSTEMATICS  3.1  HISTORY OF  LEAD ISOTOPE INTERPRETATION  Houtermans to t a c k l e from  the  (1946) and  concept  radioactive independantly  the  i n c r e a s e of  uranium the  time  and  of a d d i t i o n  d e c a y of u r a n i u m  and  lead with  d e r i v e d the  i n source  ages.  and ore  the  term  lead  of  lead  v a r i o u s ages were u s e d formable  ore  proposed  that this  composition  lead.  'anomalous l e a d  Stanton curve  1  and  Russell  s i n c e the 1968)  lead  formation reviewed  With  i n t h e model were  was  i n t r o d u c e d to excess  ore  (1959),  model  isotopic  d e p o s i t s of for  con-  therefore  t h e d e v e l o p m e n t of  isotopic  a n e a r l y homogenous  maintained  an  almost  of the e a r t h . the  govern  different  anomalous l e a d , t h e  represented  Th/Pb r a t i o  which  lead  e v o l u t i o n of  t o c o n s t r u c t a growth c u r v e  and  of  to primeval  The  s e v e r a l conformable  u p p e r m a n t l e , w h i c h had  applicability  time.  inadequacies  o f d e p o s i t s d e r i v e d from  (Kanasecwich,  thorium,  a r e d e p i c t e d i n F i g u r e 3.0.  data  the  paper  and  fundamental equations  a s i d e from from  first  radiogenic lead, derived  d a t a w h i c h gave n e g a t i v e or  Nevertheless,  composition  of  r e g i o n s c h a r a c t e r i z e d by  contents  i n c r e a s e of a v a i l a b l e  categorize  (1946) were among t h e  r a d i o g e n i c l e a d over  thorium  highlighted  Holmes  constant A  the p r i n c i p l e s  i s o t o p e m o d e l s as known i n t h e  source, U/Pb  summary and late  the 1960's.  23  Single-stage  ~1  10  I  1  12  1  2 0 6  1  1  14  1  16  1  r-  18  Pb/ ° Pb 2  4  F i g u r e 3.0 Model e v o l u t i o n of l e a d w i t h t i m e (from K o p p e l and G r u n e n f e l d e r , 1 9 7 9 ) . A: Diagram 207pb/204pb v s . 206pb/204pb showing s i n g l e - s t a g e growth c u r v e s w i t h u as a p a r a m e t e r and s i n g l e - s t a g e i s o c h r o n s . B: Diagram 208pb/204pb vs 206pb/204pb showing s i n g l e - s t a g e growth c u r v e s w i t h u and w as p a r a m e t e r s .  24  Refinements curve  ( d e c a y c o n s t a n t s f o r U and  primeval and  of the parameters  lead,  analytical  e t c . ) as w e l l  i n the  late  1969).  The  effects  1 960's  ages were r e v i e w e d  and  demonstrated  Several environments simulate  and  average  d a t a more c l o s e l y . related  t o t h e age  explained  Doe  and  Kramers  isotopic  apparently  Stacey  used  interpretation  Cumming and to the  calculated  a single  mixing  curves that  stage curve,  of  different  fitted  stage c o n d i t i o n s source  crustal and  the  model i n w h i c h corresponded  differentiation,  and  uranium-depleted  (1975) gave an  sudden e p i s o d i c  by  and  materials.  a two-stage  o f an  the  parameters  calculations  s t a g e c u r v e a t 3.7Ga  Richards  model  curve i n c h a r a c t e r i z i n g  in their  (1975) e s t a b l i s h e d  g e n e r a t i o n o f an u r a n i u m - e n r i c h e d environment.  Cooper e t a l . ,  (1974) c h a n g e d t h e  single  t o a t i m e o f major  the  were t h e n d e v i s e d t o  heterogeneous  the d e p a r t u r e of the second  of  modifications  involving  evolution  of the e a r t h  chemistry  time.  models,  the d e p a r t u r e from  mixing of s e v e r a l S t a c e y and  through  isotope  from  o f such  m u l t i - s t a g e growth, lead  These  growth  c o m p o s i t i o n of  i n lead  c o n s t a n t s on  of the d a t a  mathematical  the  i n the r e c a l i b r a t i o n  (1974).  the inadequacy lead  isotopic  improvement  decay  by O v e r s b y  of o r e  to c a l c u l a t e  ( S t a c e y e t a_l. , 1 969,  o f new  the d e v i a t i o n s  the e v o l u t i o n  Th,  methods, r e s u l t e d  curve  emphasized  as  used  alternative  model e s p o u s e d  by  Stacey  25  and  Kramers  w h i c h U/Pb material  (1975) by and  Th/Pb r a t i o s  f o r conformable  Following Zartman Hein  processes  by  approach to distinct  the  means of  Their  plumbotectonic  and  model  by  proportions  lead evolution  long  with  of  by  high  upper  and  crustal  Zartman  of  was the  Sinclair  various  different Pb.  These differences  isotope  (1982) c o n s t r u c t e d  specifically  applicable  Canadian C o r d i l l e r a  Th/Pb r a t i o s .  in lead  and  global  time.  growth c u r v e t h a t  u/Pb  Th  evolution  between  enough t o p r o d u c e marked  S u b s e q u e n t l y , Godwin and  autochthonous p o r t i o n  U,  lead  a more  mixing by  and  geological  furnished  simulating  and  that  t e c t o n i c concepts with  idealized  existed  in  source  Armstrong  model  environments — each c h a r a c t e r i z e d  environments  'shale'  (1968) and  computer m o d e l i n g ,  lead evolution  concentrations  i n the  t h e s e e m p i r i c a l m o d e l s , Doe  Armstrong  r e l a t e d to p l a t e  systematics.  increased  model  ore.  following  (1973), p r e s e n t e d  a continuous evolution  constantly  development of  (1979),  incorporated,  in  presenting  This  part  character  as  of  the  to  the the  characterized Cordillera  defined  by  Doe  is  and  (ibid.).  This Godwin and  study  used a remodeled  Sinclair  (1981; 1982)  'shale' to o b t a i n  growth c u r v e a better  (cf.  f i t with  the  26  lead  d a t a on  galena  The  reasons  3.2  BASIC PRINCIPLES AND  The  time  i n one  or  f o r ore  distinct  corresponding  to  a major  evolution  specific  isotopic  transfer  implies  of  active  f o r m a t i o n of  geological  new  affinities  u r a n i u m and  compared t o d e p l e t i o n  3.4.  the  reservoir  processes  length  the  and  age lead  evolved  systems  or  and  broadly  f o r magma  of  time to  an  acquire  o c c u r s between  to another (orogenic  Th/Pb r a t i o  and  and  c r u s t ) , have u n d e r g o n e  system  thorium  has  time  uranium  common  Th/Pb c o n t e n t s ,  episodes,  characterized  due  to  them.  generally  the  t o upper c r u s t a l  i n environments  materials.  that  of  to  environments,  c r u s t a l segments, e t c . ) and  lead,  The  before mixing  from one  U/Pb  crustal  and  source or  signature  lead  of  closed  these  for a sufficient  change i n t h e of  U/Pb  upper mantle or  isolated  lead  in successively  by  lower  cycles  material.  I t i s assumed t h a t  (e.g.  in section  method f o r e s t i m a t i o n s  characterized  generation  Formation.  isotopic ratios related  geochemical  formation  environments.  The  discussed  i s b a s e d upon measurement o f  through  E a g l e Bay  EQUATIONS  in lead  s e t t i n g and  of  i n the  changes a r e  provide a useful  conditions method  these  wide r a n g e  geological thorium  for  from d e p o s i t s  involving  by  a  preferential rocks  mantle  and/or  a  27  Age rely  d e t e r m i n a t i o n s on g a l e n a u s i n g  on t h e measurement o f l e a d p r o d u c e d from u r a n i u m  (206pb, Galena  207pb),  and from t h e t h o r i u m i s o t o p e  i s used because  composition elements of  after  crystallization  i s ' f r o z e n ' due t o t h e a b s e n c e  i n i t s structure.  a sample  radiogenic  lead  o v e r 204pb, whos n a t u r a l  ratios  will  therefore  ratios  from  the decay of uranium  rate  of  of  difference  does n o t  initial  and t h o r i u m .  of each p a r e n t i s o t o p e  has d e c a y e d  since  isotope  and t h e into  thus about formed.  accordingly  half  The a b o u t 75%  235rj i s o t o p e had d e c a y e d t o 207pb by 3. OGa  and s u b s e q u e n t  g e n e r a t i o n o f 207pb i s s m a l l .  i n the r a t e of i s o t o p i c  i s o t o p e s over time i s r e f l e c t e d  the  isotopic  growth  ages  the earth  shorter;  two  Model  component  of the  i n c r e a s e w i t h time from t h e i r  o f 235rj i s c o n s i d e r a b l y  1970);  abundance  t h e same a s t h e age o f t h e e a r t h ;  the p r i m o r d i a l  (Doe,  of r a d i o a c t i v e  The t i m e t a k e n f o r t h e 238u t o d e c a y  t h e 238u i s o t o p e  half-life  isotopic  o f d e c a y and p r o d u c t i o n o f t h e r a d i o g e n i c  abundance.  206pb i s a b o u t  decay.  The 206pb/204pb, 207pb/204pb, 208pb/204pb  g o v e r n e d by t h e h a l f - l i f e  parent  method  isotopes  i t s lead  i s computed and e x p r e s s e d as t h e r a t i o  with time.  The  (208pb)  The amount o f r a d i o g e n i c  change  is  t h e common l e a d  p r o d u c t i o n o f l e a d from t h e s e by t h e smooth f l a t t e n i n g o f  c u r v e toward younger  c a n be c a l c u l a t e d  This  ages  (Fig.  f r o m measured  3.0).  isotopic  ratios  28  Schematic Evolutionary of t h e M u l t i - s t a g e for  O r e Deposits  4Ga 1st Stage r  - * 1  / = 32.2 1  ion of the L  rz  T  I  3Ga  2Ga  2nd Stage  I I  " h  LJ  *1  Present  3rd  Stage  I II I II I '  c  c  5  1Ga  I  I  w  Lead  in t h e E a g l e B a y F o r m a t i o n  I I  lion -  5Ga  History  u =9.74 w = 37.  1  -5  9  0  j  a>  •  W = 12.16 w = 45.35  </> 1 — u  1  1  1  t 2 = 2.0Ga t  1  = 3.7Ga  T = 4.55Ga  F i g u r e 3.1 Schematic e v o l u t i o n of the lead i n galena from the Eagle Bay Formation i s as f o l l o w s (modified from Faure, 1977): system 1 s t a r t s T years ago and e x i s t s f o r a p e r i o d of time equal t o T - t i . At t i the lead i s t r a n s f e r r e d t o system 2 and continues to evolve during i n t e r v a l t l - t 2 . At time t2 the l e a d i s t r a n s f e r r e d t o system 3 and r e s i d e s there f o r t2-t3 y e a r s . At t3 the lead i s withdraw and f i x e d i n g a l e n a — a n environment c o n t a i n i n g no uranium or thorium--so that between t3 and present no f u r t h e r i s o t o p i c e v o l u t i o n o c c u r s .  29  Table  3.0  Equations  used  i n lead  1  (2  2  ( « ' P b / * o « P b ) t = (5 0 7 P b / 5 0 4 P b ) 0 +  3  i s o t o p e model  calculat ion  P b / 2 0 4 Pb), = ( 2 0 6 Pb/ J 0 4 Pb) 0 + u (e Xs T - e X » l )  0 4  ii  ^( eX s5T _ e- X5s t ) X  T  A  l  137.88 (208Pb/J04Pb)t = (J08Pb/304Pb)0 + W ( e 2 T - e J ) X  ( 2 0 6 P b / 2 0 4 P b ) 0 = a 0 = 9.307 ( 2 0 1 P b / 2 0 4 P b ) 0 = b 0 = 10.294 ( 2 0 8 P b . / 2 0 4 P b ) 0 =c 0 = 29.479  X  t  primordial lead (= Pb isotopic composition at timeT) (Tatsumoto et a l . 1973)  T = age of the Earth (calculated with the new decay constants) = 4.57 b.v. (Tilton, 1973).  (207Pb/204Pb)(-b0 (2  P b / 2 0 4 P b ) t - a0  0 6  (eXsT — e 5 )  ,  X  137.88  1  (e. A*ss T1 - e'„ X 8 i ,  '  This is the equation of a straight line, the so-called isochjon. 7  204  / J  W  =  =  Pb Pb.  238  (e sT _ X  = b0 +  u  232  /  2 0 4 p  T  h  /  137.88  (  X e  s ) t  e 8T..eX8t) X  2  06 Pb  204  Pb.  - a0  b  2 0 4 p  b  X 8 , X s , X j : decay constants of 2 3 8 U ,  2 3 S  U,and  2 3 2  Th respectively.  (see Steiger and Jager, 1977: Subcommission on Geochronology: Convention on the use of uniform decay constants in geo- and cosmochronology; EPSL, 36, 359-362). The recommended constants are: Uranium:  X ( 2 3 8 U ) = 1.55125 x 10"1 ° / y X ( J 3 5 U ) = 9.8485 x 1 0 - ' ° / y atomic ratio 2 3 8 U / 2 3 5 U = 137.88  Thorium:  X ( J 3 2 T h ) = 4.9475 x 10" 1 1 /y  30  of  galena  use  these  by  solving  equations  equations  t h e number, and  s u c c e s s i v e environment  from  which  or  approximated.  in  the environment  from  to  be  Furthermore  This  formed  the  and  the g a l e n a . by  Watson, 1 9 8 1 ) , and  been o b s e r v e d  of g a l e n a  due  Evolution Formation  f  to  i s assumed be  framework.  of galena  is directly  process  system  which  can  also  be  marked r a d i o g e n i c e n r i c h m e n t (Russell  and  Farquhar, of the  G u r j u r d i s , 1973;  in  1960;  isotopic  Richards,  of  the  lead  i n the d e p o s i t s hosted  1981;  by  the  Eagle  follows a multi-stage history schematically The  first  two  s t a g e s of t h e  a r e assumed t o have f o l l o w e d t h e S t a c e y i n which the  composition  lead developed  (inferred  t o be  followed  started  stage  that  at  Kramers  from  that of t r o i l i t e  T established  a second  lead  and  initially  T a t s u m o t o e t a_l. , 1 973 ) a t t i m e by  known  1982).  i n F i g u r e 3.1.  (1975) model,  each  fractionation  should  tectonic  lead  To  t o metamorphism have been r e p o r t e d i n  et a l .  primeval  model age  the  of  generated,  s i g n s of r e - e q u i l i b r a t i o n  Brevart  evolution  Th/Pb, due  composition  events;  s t u d i e s (Cumming and  depicted  any  3.0.  d e r i v e d must be  t y p e of m i n e r a l i z i n g  several  Bay  and  I n some c a s e s  subsequent  d e p o s i t s has  composition  l e a d was  w h i c h g a l e n a was  isotopic  t o the time  disturbed  characteristics  w i t h i n a known g e o l o g i c and  i s because  related  vein  Change o f U/Pb  negligible.  interpreted  1 to 3 f o r t2 i n Table  a  lead,  4.57Ga,  a t 3.7Ga w i t h h i g h e r u  31  and w v a l u e s — d e p a r t u r e o f t h e s e c o n d  stage corresponds t o the  a p p r o x i m a t e age  f o r the i s o l a t i o n of the lower mantle  mixing  The  system.  last  from the  stage of the l e a d e v o l u t i o n f o r the  d e p o s i t s o f t h e E a g l e Bay F o r m a t i o n i s a p p r o x i m a t e d by ' s h a l e ' c u r v e o f Godwin and S i n c l a i r  (1982).  the  This l a s t stage,  h o w e v e r , a p p e a r s t o more c l o s e l y m o d e l t h e l e a d e v o l u t i o n i n t h e E a g l e Bay F o r m a t i o n when i t i s a n c h o r e d t o t h e S t a c e y Kramers  (1975)  c u r v e a t 2.0Ga.  curve i s developed i n section  3.3  C o n s t r u c t i o n of the  and  remodeled  3.4.  ANALYTICAL PROCEDURES  3.3.1  Sample Ore  Description  samples  were c o l l e c t e d  mineralized occurrences l i s t e d  from 37 d e p o s i t s  i n Table 4.1  and  and d e s c r i b e d i n  A p p e n d i c e s A and C.  A l l s a m p l e s were s e l e c t e d  r i c h h o r i z o n s and/or  from c r o s s - c u t t i n g m i n e r a l i z e d  I n s e v e r a l d e p o s i t s b o t h m a s s i v e o r e and v e i n were s a m p l e d  from  structures.  mineralization  t o determine the e f f e c t s of d i f f e r e n t  o c c u r r e n c e on i s o t o p i c c o m p o s i t i o n .  sulphide  t y p e s of  A l l t h e l e a d a n a l y s e d was  e x t r a c t e d f r o m hand p i c k e d g a l e n a and p r e p a r e d a c c o r d i n g t o t h e methods d e s c r i b e d  3.3.2  Analytical Lead  i n Appendix  B.  Precision  isotopic  r a t i o s were m e a s u r e d on a VG  Isomass  54R  32  solid in  source  mass  spectrometer  the Geochronology  University  of B r i t i s h  interfaced  Laboratory  a HP-85 computer  o f R. L . A r m s t r o n g  Columbia.  a t The  S e v e r a l b l o c k s of data  routinely  taken  sample l o a d .  The r e p o r t e d  (Appendix  C) r e p r e s e n t t h e n o r m a l i z e d  mean o f t h e s e  Within  run p r e c i s i o n ,  deviation, of  f o r each  with  i s usually  Broken H i l l  expressed  as t h e p e r c e n t a g e  b e t t e r than  Standard  (BHS-UBC1)  duplicates  (Appendix  the  Thirteen determinations  runs.  C) m o n i t o r e d  course  of t h i s  values  t o compute t h e a v e r a g e  empirical using  mass  This  values factor  results data.  standard  Repeated  measurement  and a n a l y s e s o f the a n a l y t i c a l  p r e c i s i o n of  o f BHS-UBC1, made d u r i n g t h e  were added t o 35 p r e v i o u s l y o b t a i n e d  fractionation  accepted  (1981 ). of  study,  0.05%.  were  ratio  given  correction  i n Table  factor  was  f o r BHS-UBC1 e s t a b l i s h e d by was  used  to normalize  3.1.  An  calculated Richards  the i s o t o p i c  ratios  a l l analyses.  The less  than  of v a l u e s  maximum v a r i a t i o n 1.0%.  observed  The a v e r a g e d  a r e 0.023,  0.019  differences  confidence sets  on t h e d u p l i c a t e a n a l y s e s  respectively.  errors  arise  from  Paired-t test  e s t a b l i s h e d with  t h a t no s y s t e m a t i c b i a s e x i s t s  of d u p l i c a t e a n a l y s i s .  conditions  between t h e two s e t s  and 0.054 f o r t h e 206pb/204pb,  207pb/204pb and 208pb/204pb r a t i o s conducted  i n duplicate analysis i s  between t h e d i f f e r e n t  However, e v e n under fractionation  95%  optimal  processes  (which  TAELE 3.1: Statistics related to the calculaticn of mass f ractkinBticn factors using Broken Hill Standard (BHS-UECI).  abs +  15.962 15  0.007  15.32^  0.005  35.653  0.056  1 .062307  0.020032  0.650816  0.000705  O.0D1  15.300  0.000  35.359  0.002  1.061636  0.000016  0.669966  OD000O9  Average (n=66) Std. Dev. % Std. Dev.  15.950  0.003  0.002  35.613 0.0021 0.006  0.010  1.061732 0.00D019 0.002  0.001330  0.650609 0.0COO17 0.0C&  0.000039  0.033  15.311 O.C060 0.Q39  BH3dJECl  16.006 0.001  15.330 0.007  Maximim rtinimLfn  Error Corr. Fact Precision  .m  0.0053  1.003377 0.000112  1. BHS:UBC standard  valLEs  207/204  Lead Isotope ratios abs + 2D8/2D6 abs +  Z16/2D4  1 .005169 0.000205 fran double  spike analyses  206/207  abs +  206/20B  35.651 0.007  1.039696 0.007  0.66B907  1.006734 0.000121  0.993237  0.993651  0.000013  0.00D061  reported  by  Richards 1981 .  0.018  abs +  34  cause p r e f e r e n t i a l  d e p l e t i o n of e l e m e n t s ) ,  measurement o f t h e low i n t e n s i t y these  errors  generates  fractionation,  t h e main s o u r c e  isotopic  determinations  Russell,  1970),  displacement slopes the  204pb p e a k .  of v a r i a t i o n s  (Cooper  and R i c h a r d s ,  o f a p o i n t from  i n single  of  filament  1966; O z a r d  and  i n the a line  with  of c o o r d i n a t e r a t i o  times  o f t h e r e s p e c t i v e mass d i f f e r e n c e — e . g . a s l o p e o f  3Y/2X on t h e 207pb/204pb v s . 206pb/204pb d i a g r a m Russell,  i n the  Isotopic  i t s true value along  to the product  error  The c o m b i n a t i o n  i n the values.  i s m a s s - d e p e n d e n t and r e s u l t s  that correspond  ratio  a spread  and from  1970; R i c h a r d s  the  spread  and  208pb/206pb v a l u e s  e t a l . , 1981).  of the v a l u e s  along  The 204pb e r r o r  a slope equal  P  t o t h e 204pb measurement errors  causes  t o t h e 207pb/206pb  s i n c e f o r each of the r a t i o s  (206pb/204pb, 207pb/204pb and 2 0 8 p b / 2 0 4 b )  corresponding  ( O z a r d and  (York,  1969).  the e r r o r  i s related  The s l o p e s of t h e  i s d e p i c t e d on e a c h d i a g r a m  (Figs.  3.3 t o  3.5) .  3.3.3  Calculation  of Average Values  The  isotopic  average  3.3) a r e p r e s e n t e d  f o r the Deposits  composition  f o r each d e p o s i t  (Table  on c o n v e n t i o n a l 207pb/ 204pb v s . 206pb/204pb,  208pb/204pb v s . 206pb/204pb, and 206pb/207pb v s . 206pb/208pb diagrams  (Figs.  obtained  from  samples  3.3  t o 3.5).  The p l o t t e d  average  the computation  of repeated  a n a l y s e s of v a r i o u s  collected  a t the d e p o s i t s i t e  values  were  ( T a b l e 3.2; A p p e n d i x C ) .  TABLE 3.2:  Representative calculation of average galena lead isotopic values 1 for a given deposits.  Sample Number2  Lead Isotope Ratios 207/204  206/206  +  208/204  +  BIRK CREEK 3050B-001 30508-001D  18.948 18.947  0.02) 0.06)  15.718 15.741  0.02) 0.08)  38.861 38.856  0.03) 0.08)  30508-002 30508-002D  18.904 18.882  0.03) 0.03)  15.710 15.699  0.01 )  38.791  0.03)  38.751  0.03) 0.03)  30508-003 (3050B-0030  18.901 19.026  0.02) 0.30)  15.691  0.01) 0.30)  38.744  15.798  39.027  0.02) 0.30))3  3050B-004 3050B-0040  18.B96 18.949  0.02) 0.14)  15.705 15.741  0.01) 0.05)  38.755 38.9B7  0.02) 0.16)  30508-005  18.893  0.01 )  15.721  0.01 )  38.829  0.01)  30508-506 30508-506D  1B.B78 18.869  0.06) 0.08)  15.708 15.722  0.13) 0.10)  38.893 38.834  0.18) 0.18)  Olean (n=11) 18.927 Rejection level at + 2 s t . dev. 0.098  15.723  38.848  0.059  • .186  Mean (n=10)  18.907  15.716  38.848  Std. Error4  0.01  0.005  0.03  1. Similar calculation has been made apply to a l l deposits (Appendix C ) . 2. 30508 represents the number given to the deposit; 001, 002, e t c . defines different samples taken from the deposit; D, indicates duplicate analyses of the same sample. 3. Data from this run was rejected on the basis of more than 2 standard deviations from the mean. 4. Standard error = standard deviation / square root of number of samples (n).  .  36  tf 003  Birk Creek Deposit Average Calculation 15.75 -  CL  • •  o CVJ  005  CL  A  O CM  500A  15.7 1 -  002  I  v  • TI  a  4  i, Fractionation  v  •  003  O 001  004  -LJ  H  003  / / j  204 Error  i  i  i  18.85  18.95  19.05  2 0 6  Pb/  2 0 4  Pb  F i g u r e 3.2 2 0 7 p b / 2 0 4 p v s . 206pb/204pb d i a g r a m showing t h e i s o t o p i c d i s t r i b u t i o n o f a l l a n a l y s e s from t h e B i r k C r e e k a r e a . F i l l e d symbols r e p r e s e n t i n d i v i d u a l a n a l y s e s and open symbols define t h e i r average. C r o s s e d symbols i d e n t i f y d e l e t e d analysis. The a v e r a g e v a l u e f o r t h e B i r k C r e e k a r e a i s d e p i c t e d with i t s a s s o c i a t e d standard e r r o r (Table 3.2). D  37  TABLE 3.3: Average galena lead isotope values from ore deposits in the Eagle Bay Formation. Deposit Name  Map No2  Lead Isotope Ratios 207/204 208/204 206/207  206/208  1  206/204  Cluster 1 Devonian Birk Creek Homestake Rea Gold Ford  508 511 515 53B  Average (n=4) Std. Error Mean  18.907 18.854 18.869 1B.8B3  15.716 15.700 15.699 15.698  38.848 38.626 38.755 38.676  1 .20304 1 .20085 1.20192 1.20289  0.48699 0.48845 0.4B6BB 0.4B823  1B.887 +0.010  15.703 +0.004  38.720 +0.216  1.20211 +.00047  0.48767 +.00039  19.060 19.027  15.737 15.704  39.147  1.21110 1.21164  0.4B6B7 0.49027  19.143 19.142 19.045 19.142 19.090 19.126 19.130 19.146 19.131 19.0B1 19.128 19.105 19.096 19.125 19.151 19.191 19.104 19.177  15.701 15.694  33.909 38.900 36.835 3B.975 38.846 38.980 38.881 38.939 3B.069 38.899 38.885 3B.B49  1.21922 1 .2196B 1.21718 1.21925 1.21648 1.21575 1.21927 1.21779 1.21747 1.21471 1.21902 1.21716 1.21704  0.49200 0.4920B 0.49255 0.49197 0.49142 0.49151  Between cluster 1 & 2 Art Tuin Mountain  517 519  38.B32  Cluster 2 T r i a s s i c Agate Bay Lucky Coon King Tut Elsie Mosquito King Pet Spar Red Top Red Mineral 2 Silver King A O r e l l 5P Sunrise Enargite Fortuna White Rock Vavenby Silver King-Queen PS-85-175 Average (n=18) Std. Error Mean  506 518 523 524 525 526 527 531 534 536 537 541 504 513 528 542 545 54B  19.125 +0.007  15.688 15.700 15.693 15.732 15.690 15.721 15.714 15.708 15.692 15.696  0.49201 0.49170 0.48966 0.49052 0.49191  38.978 38.962  1.21650 1.21810 1.21574 1.21807 1.21987  0.49176 0.4B979 0.49016 0.49046 0.49145 0.49012 0.49220  38.936 +0.016  1.21775 +.00365  0.49138 +.00023  15.690 15.721 15.722 15.703 15.684 15.721  38.9B7 39.018 39.048 38.846  15.701 +0.003  38  TABLE 3.3 (continued) Deposit  Map  Name  No2  Lead Isotope Ratios'! 206/204  207/204  208/204  206/207  206/208  39.361 38.967 39.138 38.986  1 .22416 1 .22747  0.48838 0.49448  1 .22258 1.20528  39.235  1 .22200 1 .22509 1.22330  0.49076 0.49273 0.49364  Between cluster 2 & 3 Fluke mt McClennan  532 539  Foghorn Rexspar Birch Island  505 516 540  Tindal Rouge  543 547  19.223 19.269 19.208 19.177  15.703 15.698 15.711  19.335 19.251 19.260  15.916 15.820 15.714 15.744  19.391 19.345 19.354 19.356 19.339  15.729 15.699 15.706 15.691 15.680  39.336 39.360 39.383 39.251 39.016  1 .23279 1.23229 1.23228 1.23353 1 .23338  0.49294 0.49149 0.49142 0.49313 0.49567  19.357 +0.040  15.701  39.264  +0.008  +0.055  1 .23285 +.00026  0.49293 +.00077  19.461  15.719  39.504  1.23809  0.49263  39.080 39.156  0.49261 0.49188  Cluster 3 Leemac Red Mineral 1 Red mineral 3 Son ja Beca  546 533 535 544 507  Average (n=5) Std. Error mean 5ide cluster 3 June  521  1. Lead isotopic ratios represent calculated average values from data in Appendix C (calculation of average value i s described in section 3.3.2). 2. map no. in Appendix C i s prefixed by 30 and suffixed by analytical sample number.  39  Figure Birk  3.2 r e p r e s e n t s an example o f s u c h  Creek a r e a .  In the average  o u t s i d e two s t a n d a r d were o u t l i e r  values  value  d e v i a t i o n s from obtained  from  ore  3.2 and 3.3.  and from  Consistency  cross-cutting  d e p o s i t s where b o t h  types  indicates  that mineral  cogenetic  and f o r m e d  runs  hydrothermal  systems.  data  from  massive  in a l l  o f samples were c o l l e c t e d .  and/or  Thus  are presented i n  s t r u c t u r e s was o b s e r v e d  I n many c a s e s  falling  w i t h poor p r e c i s i o n .  between samples  similar  from t h e  t h e mean were d e l e t e d ( a s  showings o f d i f f e r e n t  from  collected  calculation,  means r e p r e s e n t i n g o n l y t h e ' b e s t ' v a l u e s Tables  data  This  h a b i t c a n be  interactive  v e i n s may r e p r e s e n t  feeder  zones t o m a s s i v e o r e .  3.4 THE REMODELED  The deposits series  average  CURVE FOR THE EAGLE BAY  lead  i n the Eagle  of c l u s t e r s  isotopic  composition  Bay F o r m a t i o n  207pb/204pb, and 208pb/204pb v a l u e s .  presence deposits. curve  o f a common  o f Doe and Zartman  evolution  i n an upper  plot  (1979),  crustal  from coherent  206pfc>/204pb,  The i s o t o p i c u n i f o r m i t y  as a whole i s b e s t  u l t i m a t e source  Because t h e data  obtained  ( T a b l e 3.3) forms a  c h a r a c t e r i z e d by h i g h  d i s p l a y e d by t h e s e t o f d a t a  FORMATION  e x p l a i n e d by t h e  f o r the lead  above t h e average a growth c u r v e  environment  i n a l lthe 'orogene'  representing the  i s used  t h e model ages f o r t h e v a r i o u s d e p o s i t s c l u s t e r e d  to  determine  along i t .  40  Figure  3-3  207pb/204pb v s 206pb/204pb d i a g r a m f o r d e p o s i t s h o s t e d by t h e E a g l e Bay F o r m a t i o n u s i n g d a t a from T a b l e 3.3. F i l l e d symbols d e n o t e d e p o s i t s g r o u p e d i n s p e c i f i c c l u s t e r s ; open symbols a r e outliers. Deposits i n c l u s t e r 1 to 3 are p l o t t e d with d i f f e r e n t symbols. B a r s r e p r e s e n t +_ 1 s t a n d a r d e r r o r a r o u n d t h e mean o f the c l u s t e r . The a v e r a g e growth c u r v e s shown a r e the " s h a l e * c u r v e of Godwin and S i n c l a i r (1982) and t h e r e m o d e l e d s h a l e c u r v e ( t 2 = 2.0Ga, u = 12.16+. 0 8 ) .  15.75  42  Figure  3.4  208pb/204pb vs 206pb/204pb d i a g r a m f o r d e p o s i t s h o s t e d by t h e E a g l e Bay F o r m a t i o n u s i n g d a t a from T a b l e 3.3. F i l l e d symbols d e n o t e d e p o s i t s g r o u p e d i n s p e c i f i c c l u s t e r s ; open symbols a r e outliers. D e p o s i t s i n c l u s t e r 1 to 3 are p l o t t e d with d i f f e r e n t symbols. B a r s r e p r e s e n t +_ 1 s t a n d a r d e r r o r a r o u n d t h e mean o f the c l u s t e r . The a v e r a g e growth c u r v e s shown a r e t h e ' s h a l e c u r v e of Godwin and S i n c l a i r (1982) and t h e r e m o d e l e d s h a l e c u r v e ( t 2 = 2.0Ga, w = 4 5 . 3 5 ) . 1  206  p  b  /  2 0 4  p  b  44  Figure  3.5 •  2 0 6 p / 2 0 8 p b v s 206pb/207pb d i a g r a m f o r d e p o s i t s h o s t e d by t h e E a g l e Bay F o r m a t i o n u s i n g d a t a from T a b l e 3.3. F i l l e d symbols d e n o t e d e p o s i t s g r o u p e d i n s p e c i f i c c l u s t e r s ; open symbols a r e outliers. Deposits i n c l u s t e r 1 to 3 are p l o t t e d with d i f f e r e n t symbols. B a r s r e p r e s e n t +_ 1 s t a n d a r d e r r o r a r o u n d t h e mean o f the c l u s t e r . The a v e r a g e g r o w t h c u r v e s shown a r e t h e ' s h a l e ' c u r v e o f Godwin and S i n c l a i r (1982) and t h e r e m o d e l e d s h a l e c u r v e ( t 2 = 2.0Ga, u = 12.16+.08). D  Cluster 3  0.495  0.024  Cluster 2 Remodeled curve - 2.0 Ga  JQ  Q. co o  0.49  CM  X) D_  (0  o  CM  0.44 0.485 H  Shale curve - 1.887Ga  0.41 0.44  0.48 1.190  1.20  1.21  1.22 2 0 6  Pb/ ° Pb 2  7  1.23  1.24  0  46  The of  approximate  c o i n c i d e n c e of the data  t h e E a g l e Bay F o r m a t i o n  Sinclair  (1982) s u p p o r t s  the u t i l i z a t i o n  of such  that  deposits  evolved  o f t h e E a g l e Bay F o r m a t i o n  consistent  characterized with  the a c t i v e  a significant  homogenized  c o n t i n e n t a l margin  crust  i n the  i n an upper  by h i g h u and w v a l u e s .  contribution  Precambrian  a curve f o r  the lead  t o d e p o s i t i o n o f t h e E a g l e Bay F o r m a t i o n , was  the d e p o s i t s  w i t h t h e ' s h a l e ' c u r v e o f Godwin and  model age e s t i m a t i o n , and i n d i c a t e s  environment  from  crustal  The c u r v e i s  setting  assigned  and i m p l i e s t h a t  o f m a t e r i a l from  recycled  to c o n s t i t u e n t rock u n i t s  there  and of the  formation.  However, galena  from  plotting  the high  the Eagle  207pb/204pb i s o t o p i c  Bay F o r m a t i o n  above t h e a v e r a g e  206pb/204pb d i a g r a m 208pb/204pb r a t i o s  resulted  s i g n a t u r e of the i n the data  ' s h a l e ' c u r v e on t h e 207pb/204pb v s .  ( F i g . 3.3). are s h i f t e d  Similarly  the p l o t t e d  below t h e ' s h a l e ' c u r v e on t h e  208pb/204pb v s . 206pb/204pb d i a g r a m  ( F i g . 3.4).  t h e d a t a on a 206pb/207pb v s . 206pb/208pb d i a g r a m reveals data error by  that  the s l i g h t  eliminating  'shale'  curve  (this  ( F i g . 3.5)  b u t s y s t e m a t i c d i s c r e p a n c y between t h e  s e t and t h e ' s h a l e ' c u r v e o f 204pb  P r e s e n t a t i o n of  diagram  i s real  minimizes  and n o t due t o a n a l y t i c a l the e f f e c t  t h e 204pb measurement e r r o r s ) . r e p r e s e n t s an a p p r o x i m a t i o n  of t h i s  error  Consequently  of the average  the  lead  47  behavior,  but does n o t f i t t h e data  closely  enough t o p e r m i t  model age d e t e r m i n a t i o n s .  Remodeling of the curve  by  used  changing  better Eagle  the parameters  coincidence with  (Figs.  applies  t h e E a g l e Bay F o r m a t i o n .  general  local  validity  variation  from  geological  Formation. parameters  The r e m o d e l e d  setting  curve  Shuswap Complex  from t h e as a p p l i e d  reviews  i s anchored  t h e changes i n  curve.  Composition,  T h i s date  o f t h e E a g l e Bay  and u V a l u e s  t o the Stacey  and Kramers  has been f a v o r e d b e c a u s e  from  granitic  (2.0 t o 2.25Ga: Duncan, 1982),  and t o t h e from  of stratabound deposits i n terrane c o r r e l a t e d  t h e E a g l e Bay F o r m a t i o n older  than  (Duncan, 1 9 8 2 ) .  the homogenization  i t is  g n e i s s of the  age o f t h e basement by t h e common l e a d method  groups  slightly  remodeled  ' s h a l e ' c u r v e due t o t h e  discussion  t o Rb/Sr whole r o c k d a t e s  The  curve represent a  characteristic  Time, I n i t i a l  (1975) c u r v e a t 2.0Ga.  three  i n the  only t o the deposits  I t does n o t d e t r a c t  made t o o b t a i n t h e r e m o d e l e d  remodeled  determined  3.4 and 3 . 5 ) .  specifically  the average  The f o l l o w i n g  Departure  The  close  deposits hosted  of the 'shale' c u r v e — e s p e c i a l l y  o f t h e Adams P l a t e a u .  specific  3.4.1  from  ina  Bay F o r m a t i o n — e s p e c i a l l y 208pb/204 v s . 206pb/204pb and  c u r v e as d e f i n e d h e r e  east  to define i t , resulted  the data  206pb/208pb v s . 206pb/207pb  in  (Table 3.4),  with  The 2.0Ga d a t e i s time  of the c o n t i n e n t a l  48  TABLE 3.4: Lead isotope values for the remodeled curve. Parameters: u = 12.16, u = 45.35, t2 = 2.0Ga Lead Isotope Ratios  Time Age1  Ga1  206/204  207/204  208/204  206/207  206/208  Present  0.0  19.582  15.736  39.515  1.24440  0.49556  Neogene  0.024  19.537  15.734  39.461  1.24171  0.49510  Paleogene  0.066  19.457  15.730  39.366  1.23693  0.49426  Cretaceous  0.14  19.315  15.723  39.19B  1.22846  0.49275  Jurassic  0.21  19.180  15.716  39.044  1.22041  0.49124  Triassic  0.25  19.102  15.711  3e.953  1.21584  0.49039  Permian  0.29  19.023  15.707  38.85B  1 .21112  0.48955  Carboniferous  0.36  18.884  15.698  38.699  1.20296  0.48797  Devonian  0.41  18.7B4  15.692  38.586  1 .19704  0.48681  Silurian  0.44  1B.723  15.688  38.518  1 .19346  0.4860B  Ordovician  0.51  18.581  15.678  38.354  1.18516  0.48446  Cambrian  0.57  18.458  15.670  38.218  1.17792  0.48297  Anchor point2  2.0  15.159  15.192  34.799  0.99783  0.43562  1. Time boundaries from DNAG Geologic Time Scale (Palmer, 19B3). 2. Calculated from stage 2 of Stacey and Kramers (1975) u = 9.74, ID = 37.19, ti = 3.7Ga.  49  basement by t h e H u d s o n i a n o r o g e n y . departure the  I t was c h o s e n  p o i n t f o r t h e model r e l a t e d  E a g l e Bay F o r m a t i o n .  to galena  Nevertheless this  r e p r e s e n t s an e s t i m a t e d p a r a m e t e r w h i c h m u l t i - s t a g e model a d o p t e d  Estimation unambiguous. environment an and  curve  Kramers  of the i n i t i a l  However, h e r e from  average  i n this  lead  starting  ratio  a t 2.OGa i s n o t  i t i s simply  assumed t h a t t h e  t h e r e f o r e correspond  Stacey  and Kramers  evolved  along  growth c u r v e o f S t a c e y  a t 3.7Ga (a s i m i l a r  assumption  made i n t h e c o n s t r u c t i o n o f t h e ' s h a l e ' c u r v e ) . ratios  point  study.  t o the secondary  (1975) s t a r t i n g  isotopes i n  i s r e q u i r e d by t h e  w h i c h t h e basement was g e n e r a t e d similar  as t h e  to the e m p i r i c a l  The  data  was  initial  c a l c u l a t e d by  (1975, p. 216) and a r e : 206pb/204pb = 15.159,  207pb/204pb = 15.192, and 208pb/204pb = 34.799.  The curve  u v a l u e o f 12.16 was u s e d  because  Omineca B e l t Sinclair, Eagle  calculated  1982).  a range  compositions u  i t r e p r e s e n t s the average  u values  (using equations  c e n t e r e d around  a u o f 12.0.  on t h e r e m o d e l e d c u r v e were a l s o  o f u on t h e p o s i t i o n  (Godwin and  f o r the data  i n Table  = 12.08 and 12.24 ( F i g . 3.3) t o d i s p l a y  variation  the remodeled  U/Pb v a l u e f o r t h e  f o r the 'shale' curve  The c a l c u l a t e d  Bay F o r m a t i o n  covered  to calculate  from t h e  3.0) c o i n c i d e n t l y Isotopic calculated  the e f f e c t  of the remodeled  of a  curve.  with  50  Utilization  of  2.OGa as  c u r v e which p l o t s  above t h e  Consequently,  isotopic  any  age  on  and  206pb/204pb r a t i o s  coincidence  of  known D e v o n i a n and  because  curve  2.OGa r a t h e r t h a n On  these  Cretaceous  1.887Ga as  of d i f f e r e n t  and  value  t o accommodate t h e  3.4.2  w  i t does n o t  and  3.4).  to the  207pb/204pb  'shale' curve.  clusters  model  The  i n c r e a s e s the 1 and  3.  This  aspect  clusters,  containing deposits  age,  a p p r o p r i a t e l y on  fall  100Ma r e s p e c t i v e l y .  the anchor  u values are  a p p e a r t o be  This  supports  less  caused  better  t h e use  p o i n t f o r the by  the  of  remodeled  the  significant (Fig.  a d v a n t a g e o u s t o change t h e  u  data.  Value  Utilization  o f a w v a l u e e q u a l t o 49.09  ' s h a l e ' c u r v e : Godwin and curve  (on t h e  i s inadequate.  2.OGa r a t h e r t h a n  Sinclair,  208pb/204pb v s .  1982)  ( v a l u e used f o r t o remodel  from  curve  the u t i l i z a t i o n  1.887Ga does not  the  206pb/204pb d i a g r a m ;  Compared t o t h e u r a n o g e n i c  s e c t i o n ) t h e change r e s u l t i n g to  g r e a t e r i n both  the remodeled curve  3.3),  3.5)  two  3.3  a  a s s o c i a t e d w i t h any  t h e o t h e r hand, t h e v a r i a t i o n s  utilization  thorium  be  c u r v e and  a t 375Ma and  of t h e d a t a w i t h  curve.  relative  between the  significant  the  composition  (Figs.  of t h e c u r v e ' s p o s i t i o n  is  remodeled  p o i n t generates  'shale' curve  the remodeled curve w i l l  upward d i s p l a c e m e n t  fit  a departure  sensibly  of  affect  Fig.  (above t2 the  equal  51  position  of the remodeled curve  the data  set, since i t only d i s p l a c e s the isochron  upward and t o t h e r i g h t Figure  3.4).  A closer  however used  lower this  than  value  f i t of the remodeled curve  behavior  of thorium  understood  less  specific  (Zartman, required  3.4.3  than  intersections  t o the data i s  This value i s  f o r the 'shale' curve;  the estimated  v a l u e o f 41 .86  (1979) t o c h a r a c t e r i z e t h e upper  plumbotectonic  model.  The  during the f r a c t i o n a t i o n  i n discriminating  from  i t does n o t i m p l y of the p r o t o l i t h  crustal  geochemical  process  i s not as  i s considered  among v a r i o u s s o u r c e  Therefore, although  to f i t the data  composition  t o 45.35.  as u r a n i u m a n d , t h e Th/Pb r a t i o  1974).  Formation,  a slightly  materials  lower  value i s  t h e d e p o s i t s o f t h e E a g l e Bay any major d i f f e r e n c e f o r these  i n the  rocks.  Summary Uniformity  isotopic hosted for  i s higher  for their  well  i s lowered  t h e 49.09 v a l u e u s e d  by Doe and Zartman  environment  to the d i s t r i b u t i o n of  ( d e p i c t e d a s p o i n t s and c r o s s e s i n  o b t a i n e d when t h e w v a l u e markedly  relative  w i t h i n d e p o s i t s and t h e r a n g e o f t h e l e a d  compositions  by t h e E a g l e  the lead  o b t a i n e d on g a l e n a  Bay F o r m a t i o n  has an a v e r a g e  indicates  upper c r u s t a l  emphasizes the involvement  of o l d c r u s t a l  Eagle  sediment  rocks.  Bay F o r m a t i o n Lead  from  and/or  from  that the p r o t o l i t h  signature.  This  basement b e n e a t h t h e  sources  the d e p o s i t s hosted  the deposits  f o r t h e E a g l e Bay  by t h e E a g l e  Bay  Formation  52  has  generally similar  Cariboo  Gold  different the  (mainly higher  (Aggarwal  the  lead  Formation  correlations  of  curve  the  the data used  (Andrew, 1982)  by  'shale' curve  approximation  the d i s t i n c t  3.5  MODEL AGE  Using  and  Bay  similarity Bay  the  indicates  to the average  that  behavior  r e m o d e l e d c u r v e more c l o s e l y  Formation.  following  T h i s remodeled  discussion  clusters model  fits  curve i s  t o a s s i g n model ages  i n t h e E a g l e Bay  Cretaceous  Formation  of d a t a w i t h  to  mainly  Devonian,  ages.  DETERMINATIONS  t h e m u l t i - s t a g e model d e p i c t e d i n F i g u r e 3.1,  ages f o r t h e m i n e r a l i z a t i o n isotopic  ratios  of  3.0,  Table  lead i n  Mountain  this  supports  to the  three d i s t i n c t  Upper T r i a s s i c ,  Terrane  of the data  t h e p u l s e s of m i n e r a l i z a t i o n represented  In a d d i t i o n  (1986).  the  the  the S l i d e  Struik  the E a g l e  throughout  i n the  significantly  by  But  lead  s i g n a t u r e of d e p o s i t s i n t h e E a g l e  is a possible  from  and  N e s b i t t , 1984).  established  lead.  is  to the  207pb/204pb v a l u e s ) from  i n the B a r k e r v i l l e  Proximity this  and  isotopic  and  compositions  (Andrew, 1982), and  Intermontane B e l t  Group in  veins  isotopic  can  be  of the d e p o s i t s .  d e r i v e d from By  combining  t h e e q u a t i o n o f a f a m i l y of  ( i s o c h r o n s ) p a s s i n g through  the anchor  the  p o i n t of  measured  equation  straight the  model  1 and  lines remodeled  2  53  shale  curve  obtained. lead of  a t 2.OGa on S t a c e y  and K r a m e r s '  (1975) c u r v e  The s l o p e o f t h e a p p r o p r i a t e i s o c h r o n on w h i c h t h e  isotopic  composition  lies  c a n be u s e d  t o determine  t 3 and t o a s s i g n a model age f o r t h e g a l e n a .  equation  i s t r a n s c e n d e n t a l , t3 cannot  conventional iterative  be d i r e c t l y  c a l c u l a t e d by  t o approximate the best value  isotopic  values  for t3.  were made  ( T a b l e 3.3.) f o r e a c h d e p o s i t .  t h e 207pb/204pb, 206pb/204pb s l o p e model ages a r e v e r y  sensitive  t o s m a l l changes  intercept  o f 0.1% ( c o m p a r a b l e  large variations  Consequently,  i n m, v a r i a t i o n s  model ages  error) resulted i n ( d i f f e r e n c e s of  f o r some o f t h e d e p o s i t s i n c l u s t e r 1 ) .  t h e s l o p e model ages o b t a i n e d  were n o t u s e d .  i n t h e 207pb/204pb  to experimental  i n the c a l c u l a t e d  100Ma were o b t a i n e d  deposits  S i n c e t h e above  o f t h e s l o p e m, and t 3 d e t e r m i n a t i o n s  the average  Because  a value  a l g e b r a i c methods, and computer programs use an  calculation  Calculation using  c a n be  f o r each d e p o s i t  I n s t e a d , ages o f t h e c l u s t e r e d  were d e t e r m i n e d  by where t h e y  plot  groups of  along  the remodeled  curve.  Table (calculated section error  3.3 l i s t s  t h e mean v a l u e s  i n t h e same way as a v e r a g e s  3.3.3).  are plotted  T h e s e means w i t h  remodeled  their  on t h e l e a d d i a g r a m s  Model age f o r t h e c l u s t e r s the  f o r each  curve  were t h e n  cluster  f o r each d e p o s i t i n associated standard (Figs.  3.3 t o 3 . 5 ) .  e s t a b l i s h e d from  t h e age on  a t which t h e c l u s t e r s — a r o u n d t h e i r  mean  54  values—intersected controlled exhibit and  by  the  the  greater variations.  respectively  mid-Cretaceous. deposits  T h e s e model ages a r e  206pb/204pb r a t i o s as  3 were d e t e r m i n e d  being  curve.  from  The each  i t i s these  primarily ratios  model ages f o r c l u s t e r s diagram  Late Devonian,  ( F i g . 3.3  Late T r i a s s i c ,  t o 3.5)  4.  1,2 as  and  T h e s e model ages of c o r r e s p o n d i n g  are d i s c u s s e d i n Chapter  that,  clusters  of  55  4.  LEAD ISOTOPES, MINERAL DEPOSITS AND  4.1  INTRODUCTION  The the  lead  Eagle  dominant  Formation  on  of  remodeled curve Deposits  was  the  markedly  are  are  composition  host  correlation  c o n s i s t e n t with  suggest  p a r t of u n i t  other an  assigned  i n Table  critera  which  by the  4.0).  between t h e and  distinct  sometimes  permits  w i t h , or  are  rocks.  and  c o n s t r u c t i o n of  and  Bay  has  metamorphism, w h i c h among t h e u n i t s .  (see s e c t i o n age  composite  Formation  t h e D e v o n i a n age  Upper T r i a s s i c  EBG,  the  chapter  t h r e e main g r o u p s a l o n g  contact relationships  e s t a b l i s h e d by  by  isotope signatures define genetic  intense deformation  commonly o b s c u r e s  data  their  This  on  d e p o s i t s as d e f i n e d  s u c c e s s i o n s w i t h i n the Eagle  been hampered by  data  into  3.  between d e p o s i t s t h a t a r e o o g e n e t i c  younger than  stratigraphic  lower  lead  in isotopic  Stratigraphic  lead  data  component  of d e p o s i t s hosted  between t h e s e  a l l o w model ages t o be  distinctions  EBA  i n galena  ( d e p o s i t s i n each c l u s t e r  difference  isotope  lead  sharing similar  clusters  upper c r u s t a l  e s t a b l i s h e d i n Chapter  the d i f f e r e n c e s  clustering  links;  i n f l u e n c e of an  isotope composition  Bay  focuses the  STRATIGRAPHY  f o r the  2.3.1).  f o r the  Lead unit  However  structurally  i s c o n s i d e r e d t o be  Cambrian  by  TABLE 4.0: C l a s s i f i c a t i o n and name of deposits within discrete clusters of data defined in Figures 3.3 to Deposit Classification  3.5  Host Unitl  Deposit Name  Map No1  EBA  E8F  Birk Creek Homestake Ford Rea Gold  50B 511 538 515  EBS EBG  Art Twin Mountain  517 519  Stratiform Oogenetic with host rocks  EBG  Agate Bay Lucky Coon King Tut Elsie Mosquito King Pet Spar Red Mineral 2 Silver King A Orell 5P  506 518 523 524 525 526 527 534 536 537  Replacement  EBQ  Red Top Sunrise  531 541  Veins  EBA  Cluster 1 Devonian Volcanogenic Oogenetic with host rocks  Between cluster 1 & 2 Veins  Cluster 2 T r i a s s i c  EBG  Enargite  504  Fortuna White Rock Vavenby Silver King-Queen PS-85-175  513 528 542 545 548  TABLE 4.0  (continued)  Deposit Classification  Host Unitl  Deposit Name  Map No1  Stratiform Replacement  EBG EBQ  Fluke Mt McClennan  532 539  Uranium (volcanogenic) Vein  EBA  Rexspar Foghorn Birch Island Tindal Rouge  516 505 540 543 547  EBA  Leemac Red Mineral 1 Red Mineral 3 Sonja  546 533 535 544  EBA  Beca  507  June  521  Between cluster 2 & 3  Cluster 3 Vein  Replacement (?)  Baldy EBG  Beyond cluster 3 Vein  1. Host Unit and Map No. are on Figure 4.0. Map no. in Appendix C i s prefixed by 30 and suffixed by analytical sample number.  58  Schiarizza  (1986).  completely  unambiguous, a r e  geological  data.  4.2  CLUSTER 1:  Two  I n t e r p r e t a t i o n s proposed constrained  d e p o s i t s , Rea  s h o w i n g s , B i r k C r e e k and  A p p e n d i x A)  are  enclosed  isochron  the  remodeled curve  are  hosted  of  the  Eagle  succession strongly and  and  succession  cluster  ( F i g . 3.3  relict was  by  orthogneiss  i n t e r p r e t e d by  i n t e r l a y e r e d with,  s e q u e n c e composed o f  but  facies.  phyllites,  y i e l d e d a Devonian,  EBP  EBP).  Conodonts found  yielded a mid-Mississippian  (EBA  and  EBF)  of  phyllite,  plagioclase locally  visible. a deformed sequence  and  EBF a  are turbidite  sandstone, g r i t  from t h e  and  metavolcanic  372+_1lMa d a t e  age  four  b o d i e s ) composed  volcanic  i n two  4.0,  conformable  o v e r l a i n e d by,  Zircons  Fig.  These  (1981 ) as  argillite,  two  Devonian  3.5).  U n i t s EBA  mostly  rocks  unit  are  to intermediate  (unit  1985).  4.0,  chloritic  and  Preto  minor c a r b o n a t e s  Schiarizza,  to  the  T h e s e u n i t s form a  igneous textures  felsic  Homestake, and  (Table  1 around  w i t h i n which q u a r t z  metamorphosed t o g r e e n s c h i s t  ( F i g . 4.0)  Ford,  quartz-sericite-phyllite,  recrystallized  partly  and  Devonian v o l c a n i c u n i t s  separated  schist, and  by  by  Formation.  foliated  phenocrysts This  Bay  (locally  sericite  not  s u b s t a n t i a l l y by a v a i l a b l e  Gold  mineralized  occurrences  although  DEVONIAN COGENETIC DEPOSITS  mineralized  on  here,  (Preto  limestone  (Osagien  and  beds of  to e a r l y  Devonian to Permian F e n n e l l Formation  5g  I UF I Upper structural division: pillowed and massive meta-basalt. minor chert 1 if I Lower structural division: pillowed and massive meta-basalt and ribbon chert, limestone, diorite, gabbro, quartzf eldspar, porphyry, rhyolite Mississippian  I EBP I  Phyllite and slate with interbedded sandstone and grits  Devonian a n d / o r M i s s i s s i p p i a n  I EBF 1 Feldspathic phyllite (intermediate to felsic tuff) Devonian  I EBA I Sericite-auartz-phyllite and schist (intermediate to felsic volcanics and volcanoclastics) D e v o n i a n a n d / o r older  1 EBS I Mixed meta-sedimentary seouence (phyllites) | EBC I Calcareous chlorite-schist, fragmental schist (mafic to intermediate volcanics) | '•]. 1 Tshinakin limestone fr--^  mixed phyllite ( E B C p )  [  -| quartzite (  \  )  polymictic conglomerate ( E B C c g )  [  I  T-EBG ( ? Triassic )  EBCq )  Lower Cambrian a n d / o r older IEBQ I  Chlorite-muscovite quartzite. chlorite-muscovite-quartz schist and minor meta-sediments (SDQ)  I EBH I  Quartzite. grit and chlorite-sericite-quartz schist  Intrusives Jurassic & Cretaceous  [ '• 11 \\ Raft batholith. Baldy batholith, Scotch Creek plug Late Devonian  I Qgn I Granite and granodiorite orthogneiss Symbols  Mineral occurrences • O Cluster 1 (Oevonian) • •  A & Cluster 3 (Cretaceous)  Cluster 2 (Triassic)  0 Cluster 4 (Tertiary) X  Outliers  Faults f^*"  Thrust fault (this study) Thrust fault (Schlarizza et al, 1984)  F i g u r e 4.0 G e o l o g y o f t h e E a g l e Bay F o r m a t i o n showing t h e l o c a t i o n o f t h e sampled m i n e r a l d e p o s i t s w i t h i n t h e major t h r u s t u n i t s ( m o d i f i e d from S c h i a r i z z a and P r e t o , 1984).  60  61  Meramecien:  O k u l i t c h and Cameron, 1 9 7 6 ) . B a s e d on t h e s e  determinations, assigned  a bracketed  to these  Rea  Gold  Devono-Mississippian  occur  w i t h i n o r n e a r t h e t o p of a f e l s i c  and  in a thicker  northwesterly  more m a f i c  D e f o r m a t i o n has a f f e c t e d  trending  pile  penetrative f o l i a t i o n .  outline  due  the s h i s t o s i t y  of t u f f s  Definite  developed  extensive  footwall alteration  development.  These d e p o s i t s a r e s i m i l a r  Goutier,  1986;  with  The to  other  lead isotopic  Thus,  although  Both  zones and  pyrite  i n many r e s p e c t s t o t h e  l e a d model age  age d e t e r m i n a t i o n s  consequently,  were c o g e n e t i c w i t h  fingerprint  to  deposits  (Hoy  and  Appendix A ) .  (EBA and E B F ) , and probably  are d i f f i c u l t  sericitization  p o l y m e t a l l i c Kuroko  A Devono-Mississippian coincident  flows.  l e n s e s and a s s o c i a t e d  by s i l i c i f i c a t i o n ,  volcanogenic  sequence  i s marked by a w e l l  folds  characterized  syngenetic  of a  similarly  and minor  i n the r o c k s .  composed of m a s s i v e s u l p h i d e  exhibit  syncline  pyroclastic  t h e d e p o s i t s and  defined  barite,  been  and Homestake d e p o s i t s , l o c a t e d on t h e l i m b s  overturned  deposits,  age has  units.  major  included  age  f o r the d e p o s i t s i s  from t h e i r  host  units  the m i n e r a l i z i n g s o l u t i o n s  the formation  s i g n a t u r e of c l u s t e r  of the host  rocks.  1 c a n t h e r e f o r e be u s e d  d e p o s i t s which  f o r m e d under  similar conditions.  the s i l i c i f i e d  pyrite-pyrrhoti-te  rich  occurrences  62  of  the  B i r k Creek area  mineralized 4.0,  with  the  Pb-Zn-Cu o f  A p p e n d i x A)  their  and  are  not  the  composition  The  and  oogenetic either  from the  a convective  cell  soon a f t e r ,  1 9 8 5 ) . The  volcanic pile  and  EBF  intrusive  mass, w h i c h may  indicated  by  considered Goutier  t o be  leached The  by  cogenetic  with  the  deposits  lead  extracted  formation  of  isotopic  quartz the  the  the  1973;  the  of  the  1976;  underlying  larger  convective  cell,  volcanics  or  solutions in  Solomon,  porphyry  was  volcanism  formation  intrusive (Preto,  are  from  the  massive ore; horizons.  ratios  represent  an  m i n e r a l i z i n g s o l u t i o n s from  lead isotopic  the  bearing  of  origin,  interpretation.  circulating  of an  have s e t up  occurrence  observed  with  the  by  or d u r i n g  presence  Fig.  is bodies  1981;  e t aJL. , 1 9 8 5 ) .  The  rocks.  the  s u c h an  in  zones  m i n e r a l i z a t i o n probably  (Hutchison,  probable  4.0,  (Table  s o l u t i o n s a s s o c i a t e d with  from  Lydon,  property  suggests  volcanogenic  concentrated  D e v o n i a n u n i t s EBA  Ford  massive sulphide  c o n c l u s i v e l y volcanogenic  lead isotopic  deposited  lead  stratiform  compositions  statistically  the  they  may  This  Compared  feeders  t o Kuroko t y p e  the  source  associated  i n d i s t i n g u i s h a b l e from  contemporaneous with represent  the  from v e i n s  massive d e p o s i t .  v e i n s was  a v e r a g e of  suggests the  that  formation  to massive deposits  the  of  ore  (Lambert  and  63  Sato, data  1974;  S a t o and  of c l u s t e r  Sasaki,  1 are markedly  radiogenic  lead  intrusives  i s underlying  agreement  suggests that  This  the u l t i m a t e  Figure  mineralized  lead  enrichment i n  source of  Devonian  P r e c a m b r i a n basement, a c o n c l u s i o n i n of Armstrong  ( i n Jung,  1986)  ( F i g . 2.0;  o f t h e basement b o u n d a r y  4.0,  Appendix  veins A)  plotting  distinctively  Mountain  vein  occurs  has  high  barite  Homestake d e p o s i t  EBA  and  major  thrust  isolate been  Twin  model age  unit  EBG  see  t h a n t o any  1.  The  o f m i d - P e n n s y l v a n i a n , and and  Preto,  a t Twin  of the Cambrian  by S c h i a r i z z a  Mountain  from the D e v o n o - M i s s i s s i p p i a n  indicate  and  Preto  mapping by  and G o u t i e r ,  that  Mountain  unit  1986)  (1984)  the i n f e r r e d  Gold units  EBG.  The  which units  has  Corporation o r by White  m i d - P e n n s y l v a n i a n model age d e t e r m i n e d f o r t h e Twin might  1984).  t o t h e n e a r b y Rea  inferred  ( s e e Hoy  Twin  the D e v o n o - M i s s i s s i p p i a n  deposits  4.0,  i s o t o p i c compositions  (Schiarizza  ( h o s t e d by  Art; Table  of c l u s t e r  more s i m i l a r  c o n f i r m e d by d e t a i l e d  Falconbridge  lead  and  c o n t e n t o f some o f t h e v e i n s  and  EBF)  their  to the r i g h t  a lead  i n the Cambrian  (Twin M o u n t a i n  have  makes them m i n e r a l o g i c a l l y  vein  the  LEAD DATA BETWEEN CLUSTER 1 & 2  Two  not  1980),  2.3.2).  section  The  Sato e t a l . ,  radiogenic.  with the i n t e r p r e t a t i o n  on t h e w e s t e r n p o s i t i o n  4.3  1976;  thrust  (1985).  The  Mountain  actually  represents  64  an  unconformity  between  s e q u e n c e s , and t h a t as  currently  separated  the host  interpreted.  model age by i t s e l f  unit  volcanic could  does n o t r e f u t e  4.4  CLUSTER 2: TRIASSIC STRATIFORM AND  model age deposits  2 represents  ( F i g . 3.3 hosted  galena  t o 3.5).  by t h e u n i t  EBG,  plot  in this cluster. that  EBG,  they  could  however,  VEIN  lead  Several  t h e E a g l e Bay F o r m a t i o n  suggests  remobilized  and v e i n s have l e a d  The  be o o g e n e t i c  has been d e f i n e d  cluster lead 4.4.1  isotope  Stratiform  deposits unit.  (Schiarizza,  e x i s t s between t h e  The  following  d e s c r i p t i o n of the d e p o s i t s  in section  and  of  of the  4.2.2.  geology  deposits  Remobilized Lucky  t h e i r host  a framework f o r t h e d i s c u s s i o n  interpretations  Deposit  compositions  oogenetic m i n e r a l i z a t i o n  C a m b r i a n age o f t h e h o s t .  2 and p r o v i d e s  isotopic  as C a m b r i a n  model age f o r a p p a r e n t l y  a brief geological  stratiform  randomly d i s t r i b u t e d  with  Triassic  constitutes  Triassic  form of t h e s t r a t i f o r m  C o n s e q u e n t l y , a major d i s c r e p a n c y  assigned  DEPOSITS  w i t h an Upper  1986b).  the  to  EBG.  Cluster  Unit  lead  t h e C a m b r i a n age a s s i g n  unit  that  be y o u n g e r t h a n C a m b r i a n  However, t h e m i d - P e n n s y l v a n i a n  the  through  and v o l c a n i c l a s t i c  Coon, E l s i e ,  stratiform deposits King  a r e r e p r e s e n t e d by t h e  Tut, Mosquito King  and Spar d e p o s i t s  on  65  the  Adams P l a t e a u ,  the  Clearwater  stratiform  and  area  by  (Table  i s used here  conformable with  the  the  Sunrise  4.0,  m a s s i v e and volcanic  the  and  deposits  different  (section  in  the  sedimentary phyllite  with  dark  of  Geology,  on  the  and  units containing  and  phyllitic  'black  pyrite,  jack'  arsenopyrite  zonation,  of  mafic  (absent  c h a l c o p y r i t e a l s o occur.  mineral  term  layers  which c o n s i s t s mainly  amounts o f  and  rich  intermediate  in  The  deposits' i s s i l i c e o u s ;  and  the  than  overall  i n those  deposits  can  or y o u n g e r and  of  content cluster  either of  be  of  ratios  galena  1.  of as is  The  cogenetic  replacement  in  None o f  h i g h l y v a r i a b l e between, as w e l l  However, t h e  deposits  with  type  4.4.2).  Remobilization apparent  Small  deposit)  EBG,  Appendix A).  calc-silicate,  sulphide, occurs  i n these  Cambrian u n i t  EBG  siliceous  these  are  i n these  the  gangue of  sulphides  greater  mineralization  and  limestone,  deposits.  deposits  These d e p o s i t s  g r e e n s c h i s t , of  clear  the  Top  (cf_. G l o s s a r y  1979).  unit  exhibit  within,  rocks  a s s o c i a t e d with  galena.  Mosquito King  these the  The  most a b u n d a n t  sphalerite  by  graphitic  of p h y l l i t i c  quartzites. the  hosted  affinities, by  F i g . 4.0,  surrounding  fragmental  represented layers  are  Red  to c h a r a c t e r i z e d sulphides  American G e o l o g i c a l I n s t i t u t e , Adams P l a t e a u  and  from  hinge  of  the  concentration zone o f  sulphides during and  isoclinal  t h i c k e n i n g of folds.  For  deformation sulphide  is horizons  example ( D i c k i e ,  66  1985)  a t t h e Spar d e p o s i t  upright  slightly  thickness  asymmetric  offset  and/or  scale,  deformation  crystal  quartz), and  truncate  i n which  sulphide  t h a t on t h e l i m b s ;  bearing  replacement  (steel  galena,  of a r s e n o p y r i t e pyrite  i n an  apparent similar  ( F i g . 4.1). F a u l t s strata.  undulatory by g a l e n a  (observed  level  (Lucky  of the s u l p h i d e  are outlined  extinction in  and s p h a l e r i t e ,  i n polished  Coon, E l s i e  Spar d e p o s i t  over  remobilized  lenses  that these  by l a t e r  Table  deposits  o f t h e l e a d from  the s t r a t i f o r m deposits  cogenetic  represents lead.  these  deposits  and a p p a r e n t  are syngenetic but  folding.  4.0, F i g . 4.0, A p p e n d i x A ) .  probably  that  i n t h e same s t r a t i g r a p h i c u n i t  s w e l l s a r e common i n c h l o r i t i c  composition  The  T u t ) appear e q u i v a l e n t t o  Near Sqwaam Bay, c l o s e t o t h e l a k e carbonate  section  i n the Nikwikwaia  The s t r a t i f o r m n a t u r e  of the s u l p h i d e  8km s u g g e s t s  and K i n g  ( D i c k i e , 1985) i n d i c a t i n g  may be c o n t e m p o r a n e o u s . continuity  horizons  also  On a s m a l l e r  samples o f t h e L u c k y Coon and Spar d e p o s i t s ) .  syncline  from  sulphide  and r e m o b i l i z a t i o n o f s u l p h i d e s  deformation  stratigraphic  the  are concentrated  i n t h e L u c k y Coon  overgrowth of euhedral  from  fold  a t the c r e s t i s twice  features are observed  by  sulphides  local  these  Since swells  shore,  mineralized  schist  ( A g a t e Bay;  the i s o t o p i c i s similar  i n the plateau,  concentrations  The t h r u s t f a u l t  of  to the lead  t h e showing disseminated  o f S c h i a r i z z a and P r e t o  67  F i g u r e 4.1  Folded mineralized  l a y e r s , L u c k y Coon d e p o s i t .  68  ( 1 9 8 4 ) , assumed t o p a s s relocated are  southward  within  existence  of  Two 4.0,  similar this  other  semi-conformable  and  quartz-schists has is  fault  plot  limy  that  exhibit  Coon, M o s q u i t o K i n g deposits related  are  (Appendix A),  C r e t a c e o u s age conclusion because  Red  Top  2.  These d e p o s i t s  and  the  of  4.0;  The  easterly trending faulting.  The  c o n s i s t of  sulphide  i n o l d r e p o r t s as of  that  the  the  Baldy  intrusions.  Host u n i t  open  Sunrise  the  b a s i s of  i s uncertain until  intrusive new  the  and  Red  lead  cluster. age  of  z i r c o n dates  Top  deposits  were i n t r o d u c e d  the  Lucky  batholiths  However, i f t h e  Upper T r i a s s i c  r e l a t e d to the  zones  replacement  b a t h o l i t h s i s c o r r e c t then  EBQ  antiform  t o t h a t of  and/or R a f t  sulphides  (close  mineralization  sulphide  The  Fig.  chloritic  graphitic).  Spar d e p o s i t s .  from  f o r the  deposits  (Table  sheets  remobilization similar  i t p l o t s i n the  batholith  by  i s u n t e n a b l e on  interpretation  and  conformable d i s t r i b u t i o n . an  been  i n s e c t i o n 4.1.1.)  lenticular  locally  emplacement  emanating  has  (Note t h a t  zones a s s o c i a t e d w i t h  but  implying  deposit,  s t r a t i g r a p h i c p o s i t i o n i n u n i t EBQ  classified  to the  solutions  and  disrupted of  questioned  in cluster  that are  evidence  this  ( F i g . 4.0).  Sunrise  f o l d e d around  is partly  of  a l l isotopically-related  was  lenses  a discontinuous strongly  north  thrust slices  to a s p e c i f i c  to q u a r t z i t i c  that  deposits,  Appendix A),  confined  so  slightly  the  by  assigned foregoing  isotope  data,  However  any  the  Raft  e s t a b l i s h a more  69  reliable  Vein  crystallization  age  f o r the b a t h o l i t h .  deposits The  remaining  plotting  in cluster  deposits  (Table  deposits  are  group of data  4.0,  Appendix A).  The  i n d i s t i n g u i s h a b l e from  deposits.  restricted  t o any  and  spatially  distribution  isotopic  2 i s a s s o c i a t e d with  stratiform  i s not  with  The  particular  i s not  l e a d of  of  u n i t of  well defined  lead data  the  occurrence  these  the  random and  Fortuna  veins  can  the  Bay  the  vein  above is  not  Formation,  However, be  vein  from  veins  Eagle  c l u s t e r e d ( F i g . 4.0). totally  composition  their  categorized  as  follows: 1)  The  A)  trend  These of  Enargite  northward  faults  Upper  2.3);  and  occur  (Table  F i g . 4.0,  c l o s e to w e l l d e f i n e d  a s s o c i a t e d with  two  distinct  t o p r e - J u r a s s i c age, the  4.0,  bracketed  age  of  and the  Appendix  faults.  t h r u s t i n g events  of L a t e  Jurassic  age  faulting  includes  the  Triassic.  The  4.0,  V a v e n b y , PS-75-185, and  A p p e n d i x A)  occurrence model age pulse 3)  are  post-Permian  (Section  2)  and  of  are  veins  hosted i n the  i n d i c a t e s the  by  W h i t e Rock v e i n s the  Tshinakin  (Table  Limestone.  Cambrian Limestone w i t h  occurrence  4.0,  Fig.  The  Triassic  of  an  epigenetic  Triassic  i s part  of  a major v e i n  of m i n e r a l i z a t i o n .  The  cutting  Silver rocks  King-Queen v e i n of  u n i t EBG.  Since  this  u n i t a l s o hosts  system the  above  70  stratiform different  deposits, t y p e s of  i t demonstrates the  mineralization  occurrence  of  equivalent  Lead  isotope  of  age  in similar  rocks.  4.4.2  Multiple  Interpretation  Three p o s s i b l e attempt  i n t e r p r e t a t i o n s are  reconcile  the  features.  T h e s e can  be  syngenetic  and  reset 2)  to  the  lead  t o an  oogenetic  in  Short  mineralization  Upper T r i a s s i c  i n age,  event;  i t s host,  and  and  3)  u n i t EBG,  the or  mineralization part  is  metamorphism  is epigenetic,  of  age; and  is  i t , is  model  original  remobilization  the  f o r the of  lead  Rock  (in Jurassic  i n the  time) coupled with  an  f o r the  components  rocks to  s t a r t i n g an  stratiform deposits.  host  Cambrian)  p r o c e s s ) m i g h t be  s y s t e m and  radiogenic  lead  (assumed t o be  ( c a p a b l e of  homogenizing  of  radiogenic  deposition  and  rocks.  the  geological  model  leaching  the  1)  observed  Upper T r i a s s i c  i n temperature  production  the  an  t o an  increase  obtained  e x a m i n e d below i n  d e f o r m a t i o n and/or  i s o t o p i c system  t e r m growth o f  f r o m time of  resetting  as:  data  age.  Remobilization  subsequent  data with  summarized  epigenetic  with  Triassic  lead  Cambrian, but  a l l mineralization  related  of  responsible  a p p a r e n t model  This  from  efficient  model  the  l i t h o l o g i e s w h i c h have an  for  the  age  requires  uranium p r e s e n t  upper c r u s t a l  in  71  protolith of  are  enriched  uranium daughters  such  source.  The  g e n e r a t e s an  lead  i s t o be  production  increase  substantially  i n uranium  a f f e c t i n g the  p r o d u c e d would be  loosely  held  therefore  expected w i t h i n  of  i n the  and  radiogenic  in situ  rocks  uranium  206pb/204pb r a t i o  position in defect  derived  from  isotopes  without  207pb/204pb r a t i o .  relatively  growth  The  easy to e x t r a c t  radiogenic  due  structure within  the  to i t s mineral  lattice.  Post-depositional EBG  i s p o s s i b l e , but  intermediate processes  accumulation  would be  to mafic  responsible  nature  permit  limited of  f o r the  m e t a l s would have t o be  of  the  by  the  and  over  Could  lead  intense  isotopes  a long  deformation  C r e t a c e o u s have c a u s e d Certainly  the  present  within  the  deposits  deeply  a f f e c t e d the  distribution.  (Gulson  i n the  (see ore  F i g . 4.1) and  In g e n e r a l  i s known a b o u t  very  little  galena  the  radiogenic  sulphides  period  of  time  E a r l y J u r a s s i c and/or  that  to  isotope  the ?  masses  remobilization  current  l e a d may  after their the  lead  sulphide  suggests  have been added t o t h e  the  relative  controlled their  Locally derived  Furthermore  e t a_l. , 1 983 ).  r e m o b i l i z a t i o n of c o n f i g u r a t i o n of  in unit  r e - t r a n s p o r t a t i o n of  s u b s t a n t i a l e x t r a c t i o n of m e t a l s and  h o m o g e n i z a t i o n of  lead  generally  volcanics.  leaching  effective  radiogenic  therefore  initial  effect  of  formation. metamorphism  72  upon l e a d if  isotopic  composition  r e m o b i l i z a t i o n can  inconsistencies isotopes during  account  arise  released  (Richards for general  when d e t a i l s  from  e t a_l. , 1981)  are  incompatible  behavior,  Radiogenic  lattice  metamorphism m i g h t move f a r enough t o a l l o w  become i n c o r p o r a t e d  into surrounding  remobilization  and  temperature  (Doe  r e g i m e or  Hart,  mineral  1963).  extensive  them  However o n l y  ore.  a  complete  h o m o g e n i z a t i o n of  expect  that  r e m o b i l i z a t i o n mechanism r e s p o n s i b l e  a l l primary ore  Hurray,  1982).  Such an  metamorphism o n l y hydrothermal Hoy  and  Adams  Goutier,  intense  process  for  to such  d i d not  facies,  observed elsewhere i s not  would such  extent  observed  occur  and  as  intense  (Homestake  i n the  deposit,  deposits  on  the  Plateau.  would  scattered Slawson, deposit of  1986)  would  would have been o b l i t e r a t e d (Le  reached g r e e n s c h i s t  alteration  Thus low best  textures  high  M o r e o v e r , one  h o m o g e n i z a t i o n would r e q u i r e r e c r y s t a l l i z a t i o n that  to  during  permit  any  sites  hydrothermal a c t i v i t y the  even  several  considered.  unfitted  and  the  temperature  leave  the  isotopic  Alternatively  with  a n a l y s i s of  ( A p p e n d i x B) do  deposits  composition  1983), but  deposits  alteration  galena  s e v e r a l samples the  isotope  from t h e  lead isotopic  evolved  at  and  Gudjurdis,  e x h i b i t such v a r i a t i o n  lead  apparently  inhomogeneous  (Cumming and  reveals that  not  an  processes  1973; same  composition  ( s e c t i o n 3.3.2).  i n the  J u r a s s i c from  73  Cambrian  source  rocks with  straight  line--not  model age  the  lead  yielded hosted  affected  t h e age  age  the  stratiform  the Cambrian u n i t  of  the Bay  other  a d j u s t e d by  content  of Rea  Gold  and  Furthermore  isotopic  lead  would be  composition  lead—especially deposition  and  of  pre-Mesozoic Rea  Gold  isotopic This  i s not  concordant the  lower  with  the the  galena  d i s c e r n a b l e from  of d e p o s i t s c o n t a i n i n g low  and  have made  s h o r t time  the  amounts o f  interval  separates  metamorphism.  the T r i a s s i c  deposits hosted  the E a r l y  have  s i n c e s m a l l a d d i t i o n s of  more e a s i l y  when a r e l a t i v e l y  Consequently stratiform  by  of  those  Homestake d e p o s i t s s h o u l d  them more s u s c e p t i b l e t o r e s e t t i n g metamorphic  their  i s D e v o n i a n and  rocks.  to  Homestake and  have had  Triassic  i t would a l s o  the metamorphic e v e n t .  model age  surrounding  The  the  I t seems  assigned  EBG,  a  negates  re-homogenization  deposits hosted  Formation.  along  2.  caused  deposits.  model age  therefore also  since their of  lead  by  should  composition case  f o r the  fall  between m a j o r d e p o s i t s a l s o  the T r i a s s i c  i n the Eagle  deposits  in cluster  t o assume t h a t i f a M e s o z o i c  deposits  units  content  that r e m o b i l i z a t i o n processes  obtained  reasonable  uranium  c l o s e t o a p o i n t as  Comparative evidence the h y p o t h e s i s  variable  Jurassic  by  model age  unit  deformational  EBG and  obtained  i s probably metamorphic  f o r the not  an  event.  effect  74  Nevertheless  Epigenetic, An is  that  the  Upper T r i a s s i c  2 are  units  EBG  deposits  epigenetic  during  sulphides  unit  model  an  i n the  with  from  surrounding  veins,  Triassic  volcanic  that  and  lead  to  remobilization. been i d e n t i f i e d  epigenetic  of  the  levels, rocks  and  the  suggests  controlled horizons  which  by  with  rich 1  of  the  of  that  area  i t might  from a  in a  supplied  just before  age.  of  the  indicate  Jurassic event  area.  has  However  Limestone  i n c l u s t e r 2 are  Triassic  case  The  and  examples  association  with p a r t i c u l a r s t r a t i g r a p h i c  the  stratigraphy.  chemical  lead  Cambrian T s h i n a k i n fall  in  Cambrian  Recognition  Adams P l a t e a u - C l e a r w a t e r cut  the  s u c h a major  r e l a t i o n s h i p between t h e  the  extracted  rocks.  u n i t EBG  emplaced  stratigraphic  c i r c u l a t i o n that  r o c k s of  horizons  strongly  h o s t e d by  s i g n i f i c a n t because  age  I f t h i s i s the  event a f f e c t i n g the  mineralization  sulphide  event.  in favorable  sedimentary  i s o t o p i c composition  of  lodes  d i r e c t evidence  i n the  deposits  lead  the  No  replacement  l e a c h e d and  a c t i v e hydrothermal  radiogenic  whose  be  model  plotting in  stratiform deposits  solutions  time would  of  vein  or  Triassic  composition  Upper T r i a s s i c  magmatic a n d / o r m i n e r a l i z i n g  the  lead  would have been d e p o s i t e d  horizons  period  their spatial distribution.  a l t e r n a t i v e i n t e r p r e t a t i o n f o r the a l l the  cluster older  t h i s event, d i d c o n t r o l  sediments  ore  and  the  surrounding  ore  masses were  originally  The  association  of  indicates  that  they  the  sulphide  were  75  probably even  deposited  i f clearly  Triassic If  remobilized  cogenetic the  with  their  host  unit  (EBG)  later.  deposits  m i n e r a l i z a t i o n a t the  Spar d e p o s i t s model age  contemporanously  i s cogenetic  with  L u c k y Coon, M o s q u i t o K i n g  the  i s accommodated, t h e n  host  unit  rocks,  EBG,  and  the  or p a r t of  and  lead  i t , must  Triassic.  Unit the  Eagle  EBG, Bay  greenschist  fault  bounded on  Formation,  both  s i d e s by  c o n s i s t s mainly  of v o l c a n i c a f f i n i t i e s  succession  Limestone,  t h e major marker of  the  correlated  limestone  Archaeocyathids  of  i n the  entire  unit  underlain  EBG.  and  Tshinakin  o v e r l a i n by  Locally  the  reflect  original  Preto  The  limestone  margins of  e t al_. ( 1980). mapped as  succession,  alternative and  the  Bay  Limestone  is  carbonate  a single  unit  stratigraphic  in Schiarizza, age  are  complexities  for  the  greenschists.  these  terminations  bank a c c o r d i n g fact  that  representing a  interpretation  A  immediately  s e q u e n c e s of out;  Tshinakin  contains  a Cambrian  lenses  an  Formation.  (Norford  However, d e s p i t e t h e  p a c k a g e was  structural  infer  similar  abruptly  age  fragmental  containing  Vavenby a r e a  E a r l y Cambrian  1 9 8 6 ) , w h i c h have been u s e d t o  Eagle  u n i t s of  of m a s s i v e  a s s o c i a t e d with  heterogeneous meta-sedimentary  unit  other  to  this  continuous  possible given of  the  Eagle  Bay  the  be  76  Formation.  It  is  depicted from  in Fig.  the Eagle  southern  This  4.0  here as  thrust  and n e a r  present  sedimentary  sequence  Schiarizza  and P r e t o  containing  b o t h the member  s i d e of  sub-unit  EBGp seems  (1984),  greenschist  in several  interdigitated  t o be  stratigraphic  The  (i.e.  from t h e  Limestone. and  succession,  and t h e  phyllitic  occurs  only  to  n o r t h of  it  area  Limestone is  never  by f o l d i n g .  the  the  the  interbedded  in direct  contact,  contact  with  contact  d e f o r m e d and t r a n s p o s e d  and  locally  relationships  Thus t h e a p p a r e n t  c o u l d be s t r u c t u r a l  d i v i s i o n between u n i t s  on  metasedimentary  in stratigraphic the  is  the  mapped by  Furthermore,  the  on  meta-  As p r e s e n t l y  Even t h o u g h t h e  these u n i t s  limestone  slice  fault  Limestone.  with greenschist,  have been o b s c u r e d some o f  north  the T s h i n a k i n  the metasediments. appears  the  EBGcg and E B G q ) ,  places,  thrust  the T s h i n a k i n  the meta-sedimentary  restricted  distinct  a bounding t h r u s t  south.  the T s h i n a k i n  Although  between  the  u n i t EBG,  an a d d i t i o n a l  folded conglomeratic  limestone.  is  to  of  lithologically  t h e base o f  to the  (sub-units  southern  succession  is  would s e p a r a t e  v o l c a n i c rocks  with  southern part  and r e p r e s e n t  greenschist  quartzite  the  Bay F o r m a t i o n w i t h  side if  that  u n i t T-EBG,  the n o r t h e r n p a r t ,  within the  proposed  contact  rather  than  contact).  EBG and T-EBG a l s o  is  supported  77  by  marked  between the  d i f f e r e n c e s  the  was  T s h i n a k i n  meta-sedimentary  limestone  c o n t r a s t  formed  p h y l l i t i c  by  Devonian p a r t  of  the  w i t h  p r e - T r i a s s i c  u n i t  Bay  mapping are (EBG EBG  to  T-EBG)  ( F i g .  and  are  u n i t  in  T-EBG  N i k w i k w a i a and  have  not  been  mapped.  c o n t a i n  the  Lake  synform,  4 . 0 ) .  which  the Older  i d e n t i f i e d T h e r e f o r e  any  and  T s h i n a k i n  r e p e a t s  F i g .  been  s t y l e  v o l c a n i c s , of  which  EBGq,  and the  T-EBG  r e c o g n i z a b l e  2 . 0 ) ,  two  as  Formation w e l l  Bay  u n i t  more  as  (exposed the  on  age  the  f a u l t e d  u n i t s  t h r u s t  s l i c e  the on  of  F o r m a t i o n - - t h i s  E a g l e  the  the  Upper  the  understanding  d e f i n e d  between  w i t h i n  d e t a i l e d  t h r u s t  p r e s e n t l y  c o n s t r a i n t s  E a g l e  not  r e l a t i o n s h i p s  Sicamous  T r i a s s i c  s t r a t i g r a p h i c  or  the  a  C e r t a i n l y  and  whether  w i t h i n  f u r t h e r  of  numerous.  C o n t a c t  the  presence  s t r u c t u r a l  F i g .  F o r m a t i o n ,  are  e x i s t  the  Lake,  the  r e s o l v e  4 . 0 ) .  Formation Shuswap  of  b e t t e r  r e q u i r e d and  not  warping  and  e l e m e n t s .  Formation  and  g r e e n s c h i s t  Orogeny,  not  i n t e n s i t y  G e n t l e  t i g h t  T-EBG  has  the  ( s u b - u n i t  EBG does  I m p l i c a t i o n s Eagle  the  beds  o r t h o g n e i s s u n i t  Limestone  Colombian  w i t h i n  the  d e f o r m a t i o n a l  sequence.  q u a r t z i t i c  s t r u c t u r e s  in  Bay  shores  of  Sicamous  T r i a s s i c  age  for  i s  e l a b o r a t e d  on  was  c o n s i d e r e d  Upper  below.  The T r i a s s i c  Sicamous and  Formation  viewed  as  a  u n t i l  f a c i e s  r e c e n t l y  e q u i v a l e n t  of  r o c k s  of  the  78  S l o c a n assemblage, evidence contact  b u t t h e r e i s no d i r e c t  to support  this  correlation  (Okulitch,  was assumed t o be a t h r u s t  Devono-Mississippian  rocks  (unit  (Okulitch,  mapping and d r i l l  from  core  fault  1979).  (Daughtry  in. P r e t o and S c h i a r i z z a ,  transition  Formation.  green  T h i s conformable  formations  interpreted  1.  The Sicamous F o r m a t i o n  EBA  o f t h e E a g l e Bay F o r m a t i o n  (Okulitch,  unit  Formation  o f t h e E a g l e Bay between  i n two d i f f e r e n t  these  ways: unit  and i s t h e r e f o r e o l d e r ( i . e .  EBA.  of the Lardeau  p e r s . comm.,  a gradual  underlies Devono-Mississippian  members o f t h e S i c a m o u s F o r m a t i o n Index F o r m a t i o n  Bay a r e a  o f t h e Sicamous  contact relationship  two  Cambro-Ordovician) than  rocks of  However, r e c e n t  1985) s u p p o r t s  calcareous schist  h a s been  juxtaposed  i n the Blind  between a l i m e s t o n e member  a chloritic  which  t h e upper c o n t a c t between t h e  S i c a m o u s and t h e E a g l e Bay F o r m a t i o n  is  The  EBA) on Upper T r i a s s i c  t h e Sicamous F o r m a t i o n  2.  1979).  between t h e S i c a m o u s and t h e E a g l e Bay F o r m a t i o n  therefore  and  paleontological  In this  case  some  limestone  c o u l d be c o r r e l a t i v e  with the  Group i n t h e K o o t e n a y A r c  1986).  The c o n t a c t between t h e S i c a m o u s and t h e E a g l e Bay F o r m a t i o n g r a d u a l , even t h o u g h n o t n e c e s s a r i l y  inverted  by a s y n f o r m a l  (Daughtry, Triassic  structure  p e r s . comm., 1 9 8 6 ) .  c o n f o r m a b l e , and  overturned  t o t h e south  The S i c a m o u s t h e n  c o u l d be Upper  and p a r t o f i t c o u l d be e q u i v a l e n t t o r o c k s of t h e  S l o c a n Group o r t o some b l a c k s h a l e o f t h e N i c o l a  Group.  These  79  shales,  w h i c h may  r e p r e s e n t a deeper d e p o s i t i o n a l  S i c a m o u s F o r m a t i o n f o r m a more o r  comm., 1986;  the  l e s s c o n t i n u o u s band down t o  t h e V e r n o n a r e a where t h e y c o n t a i n s (Daughtry, pers.  f a c i e s of  conodonts of N o r i a n  Okulitch,  1979).  age  However, b e c a u s e  d i r e c t p a l e o n t o l o g i c a l e v i d e n c e i s l a c k i n g n e a r Adams L a k e , structural the  two  ruled  and  s t r a t i g r a p h i c r e l a t i o n s h i p s ambiguous, n e i t h e r  i n t e r p r e t a t i o n s above can  In t h i s to the  has  or  Quesnellia  t y p e of  Formation.  deposits  terrane,  rocks  which have l e a d curve  However, t h e u n i t EBG  (and  could lead are  therefore  ( A n d r e w , 1982)  rather  better  s u p p o r t e d by  of  S l o c a n G r o u p l e a d was (D.  phyllites,  of  the  be  possible  Lake.  correlated  imbricated  within  B a r k e r v i l l e Terrane. w i t h i n the  i s o t o p i c c o m p o s i t i o n of  any  N i c o l a Group r e l a t e d  than i n the  lead  Gosh, i n Logan  at  from  least  by  rocks), shale 2.  a S l o c a n type assemblage would  probably derived  1985).  the  p o s i t i o n of c l u s t e r  i s o t o p i c evidence since  A  Eagle  u n l i k e those hosted elsewhere  i s o t o p i c c o m p o s i t i o n t h a t p l o t below the  C o r r e l a t i o n o f u n i t T-EBG w i t h  the  black  were m e c h a n i c a l l y  imbrication  h o s t e d by  Quesnellia  succession  C r o o k e d L a k e area--100km e a s t o f W i l l i a m s  Snowshoe G r o u p , w h i c h i s p a r t  rocks  favored  b e e n d o c u m e n t e d by R o s s e t a l .  a r e a a T r i a s s i c sequence of  similar Bay  unequivocally  of T r i a s s i c r o c k sequences w i t h i n a  peri-eratonic affinities  (1985) from the  the  be  of  out. Imbrication  with  and  part  cratonic  be  80  4.4.3  Summary A l t h o u g h model ages  isotopic close  composition  to,  Orogeny,  the  EBG)  orogenic  sulphide was  resetting. in  cluster  is  of  case  enclosed and  ores  affected  The  Triassic  2 can  be  replacement  be  lead  the  model age as  follow:  1)  to  f i n g e r p r i n t that  subdivision  the  i n t o two  Triassic  stratiform that  are  EBG  is required.  deposits  a thrust  these  4.5  age  The  random d i s t r i b u t i o n of  uranium  and  the  or  the  complete deposits  mineralization event,  i n which  e v e n t , or  2)  the  a structural units  o r i g i n of  defined  the  the  is tested  of  Cambrian  these suggestion i n the  field,  valid.  p l o t between c l u s t e r  an  and,  u n i t EBG  LEAD DATA BETWEEN CLUSTER 2 &  reflects  EBG  separate  Until  the  Model ages f o r d e p o s i t s that  unit  i s more c l e a r l y  exists within  equally  the  of  by  of  stratiform  with  and  point  f o r the  i s cogenetic unit  the  or  Colombian  (hosted  r e l a t e d to a T r i a s s i c  used  lead  composition  Adams P l a t e a u  mineralization of  Jurassic  isotope  metamorphism t o  t y p e and  c l u s t e r 2 can  the  interpreted  with  c l u s t e r 2 i s s i m i l a r to,  metamorphic E a r l y  from  by  stratiform deposits by  i t i s u n l i k e l y that  stratiform unit  for  highly thorium  with  2 and  lead  3 are  some of  radiogenic  3  isotopic  not  interpretable.  these data  probably  component g e n e r a t e d  mineralization  compositions  by  proximal  ( i . e . Rexspar d e p o s i t  Table  81  4.0,  F i g . 4.0, A p p e n d i x A ) .  The from  hosted  and t h o r i u m  c o n c e n t r a t i o n found  by a t u f f a c e o u s t r a c h y t i c  a fluorite mainly (Preto,  barren  of uranium  1977) o b t a i n e d  Cretaceous  mineralization  Baldy  was  than  Eagle  Formation,  cluster  and m o l y b d e n i t e  the host  a t Rexspar  3.3.  zone  but  o f 236 +_ 8Ma  source  ruled out  f o r the  that the  rocks.  (Table  The  3.3) i s much  f o r t h e o t h e r d e p o s i t s h o s t e d by plots  w e l l above t h e  The 206pb/204pb and  3.3) a r e n o t as extreme and f a l l  r a n g e f o r t h e d e p o s i t o f t h e E a g l e Bay  however, s i n c e R e x s p a r  i s likely  sequence, these  t h e range of v a l u e s 1.  of u n i t  bearing  A K-Ar d a t e  i t consequently  (Table  Devono-Mississippian within  value  i n Figure  the high  f l u o r p h l o g o p i t e , and  as a p o t e n t i a l  f o r the galena  the expected  member  (1977) t h e r e f o r e p r o p o s e d  Bay F o r m a t i o n ;  with  f l u o r p h l o g o p i t e a t Rexspar  'syngenetic' with  208pb/204pb v a l u e s within  from  the average  remodeled curve  and t h o r i u m .  i n galena  This deposit,  an u r a n i u m  a s s o c i a t e d with  batholith  Preto  207pb/204pb v a l u e greater  there.  zone c o n t a i n i n g t r a c e s o f g a l e n a  mineralization.  the  composition  to andesitic  c o n t a i n s two m i n e r a l i z e d z o n e s :  composed o f a b u n d a n t p y r i t e  the  isotopic  the Rexspar d e p o s i t s i s a s s o c i a t e d d i r e c t l y  uranium  EBA,  h i g h l y anomalous l e a d  values  oogenetic  with the  s h o u l d be lower and  d e l i m i t e d by t h e d e p o s i t s i n  82  The  F o g h o r n , Rouge, B i r c h  (Table  4.0,  by  same f e l s i c  the  F i g . 4.0,  member) t h a t h o s t epigenetic  are v e i n s  i n an  v o l c a n i c rocks  (Devonian  unit  t h e R e x s p a r d e p o s i t . The  veins f a l l  to the  reflect  highly  r a d i o g e n i c component and  probably  generated  minerals  like  uranium  and  and  the  with 3),  lead  surrounding  r e l e a s e d from  veins  thorium  cannot  be  rich  isotopic  from  The consists  these  high  in situ  are  by  than  Fluke deposit  thorium  Model  was  from  Consequently  to estimate  the  a the  model lead  the m i n e r a l i z a t i o n event than  that associated  batholith  t o the  (Jung,  (cluster  Jurassic However  p e r s . comm.,  F i g . 4.0,  of d i s c o n t i n u o u s s u l p h i d e r i c h  of  rich  layers  Appendix that  are  new  1986)  veins to i t s i n t r u s i o n .  ( T a b l e 4.0,  a  involves  the Colombian orogeny.  these  of  age  radiogenic lead  the Baldy  related  lead  r o c k s , most of w h i c h  i s less  the R a f t b a t h o l i t h  f o r m a t i o n of  decay  increase in radiogenic  composition  older  the  directly  model ages y o u n g e r  a s s o c i a t e d with  link  the  environment.  B e c a u s e an  deformation  may  for  The  u r a n i u m and  growth of  used  v e i n s more l i k e l y  dates  dominated  EBA--trachytic  2.  i s ambiguous and  the m i n e r a l i z a t i o n caused these  by  i n the Rexspar d e p o s i t .  veins.  generate  area  lead data  of c l u s t e r  generated  o f a s h o r t term  f o r these  would  and  f o r these  remodeled curve age  i n the  those  determinations  locally  right  deposits  i n c o r p o r a t i o n i n the m i n e r a l i z i n g s o l u t i o n s  thorium  consideration  Tindal  A p p e n d i x A)  ratios  uranium  I s l a n d and  A)  83  semi-conformable with of  host  unit  EBG.  carbonate-rich  the  sulphide  Proximity  indicate  limy  The  s h i s t o s i t y and  that  horizons  by  intrusion.  the  of  lead  to  3.  to  a  4.6  to  larger  the  stratiform  This and  the  two  curve also  of  intrusions in  for  the  i t is closest  isotopic 3,  the from Fluke  to  composition,  i s probably  related  lead.  the  plot  sized  in cluster  3  occurrences,  (Table  4.0,  A).  i n the  Cretaceous Baldy  coincident  vein  indicates  The  the  the  link  fact that  i n the  that  with  ( c l u s t e r 3;  suggests a genetic  mineralization.  composition  but  cluster  true  a  emanating  3.5)  u n c l a s s i f i e d small  remodeled curve  relationship the  of  Beca d e p o s i t  Leemac v e i n ,  on  lead  wallrock  i s o t o p i c composition  isochron  3,  be  CRETACEOUS VEINS  F i g . 4 . 0 , Appendix  lead  lower  of  Leemac v e i n ,  The  2 and  from v e i n s  component  CLUSTER 3:  The and  those  ( F i g 3.3  a  concentrated  plots  cluster compared  was  layering  with  granitic  fluids  l i e between c l u s t e r slightly  to  to  c i r c u l a t i o n of  deposit  The  appear  deposit  mineralization  lateral The  the  compositional  zones a s s o c i a t e d  s c h i s t member t h e r e f o r e  replacement. may  the  lead  of  the  Fig.  lead  plots  has  a  Cretaceous 3.3  to  between t h e  the  batholith  batholith  3.5)  intrusion  isotopic on  the  batholith  remodeled  has  evolved  84  from a s i m i l a r Eagle  protolith  Bay F o r m a t i o n .  composition  reflects  source  as the s u r r o u n d i n g  Specifically, the d i r e c t  i n the o r i g i n  supports  the i n t e r p r e t a t i o n that  the adjacent  and g e n e r a t i o n  Shuswap Complex  of the  isotopic  i n f l u e n c e o f an upper  basement  in  the lead  rocks  crustal  of the i n t r u s i o n ;  this  the r o o t s of the b a t h o l i t h are ( O k u l i t c h , 1 9 7 9 ; see s e c t i o n  2.4.4) .  Cluster deposits  3, t h e r e f o r e ,  that are cogenetic  Accordingly,  two s m a l l  variable  values  vicinity  of L i c h e n  Claim  with  mineralized  siliceous  the  Baldy  (Table  ( F i g . 4.0) w h i c h  (Red M i n e r a l were  exhalative deposits, granitic  i s probably  showings around L i c h e n  P e t , Red m i n e r a l  claim  plug  seems  i nthe  a s a t e l l i t e of  M o u n t a i n on Adams  2, O r e l l  5P and S i l v e r  4.0, F i g . 4.0, A p p e n d i x A) y i e l d e d l e a d  signatures  t h a t were d i s t i n c t l y  Cretaceous  showings by f a l l i n g  3.  i n the  batholith.  Four other Plateau:  sampled  4.0, F i g . 4.0, A p p e n d i x A) t h a t  i n t e r p r e t e d as s y n g e n e t i c  Creek area  zones c a r r y i n g  M o u n t a i n on t h e Adams P l a t e a u  more a p p r o p r i a t e l y r e l a t e d t o a s m a l l Scotch  f o r Cretaceous  the i n t r u s i o n of the b a t h o l i t h .  o f l e a d , z i n c and s i l v e r ,  1 and 3, T a b l e  previously  i s the f i n g e r p r i n t  The s p a t i a l  different i n cluster  King-A  isotopic  f r o m t h e two 2 i n s t e a d of c l u s t e r  r e l a t i o n s h i p s between t h e s e  unclassified  85  occurrences isotopic  and  the  composition,  local  accumulation  other  nearby  different  oogenetic  mineralization similar  deposits.  i s a good example o f  through  Sonja  ages and  their  represent to  the  between  two  six mineralized  origin  of t h e  lead  for  looking deposits.  vein  ( T a b l e 4.0,  silicified  geological  distinction  the a p p l i c a b i l i t y  different  the Devonian u n i t  discontinuous  The  probably  of m i n e r a l i z a t i o n among t h e s e  similar  The  coupled with  t h a t they  for discriminating  otherwise  from  of  Mosquito King,  indicates  stratiform  types  occurrences method  Spar and  EBA  near  and  the  lead  Sonja  A p p e n d i x A)  Clearwater.  zone a l o n g  evidence,  t h e m i n e r a l i z a t i o n on  F i g . 4.0,  the  cuts  I t occurs  s i d e of a major  data  that plots  property  as  a  dyke  in cluster  3,  i s e p i g e n e t i c and  Cretaceous.  Another  deposit with  the  Beca d e p o s i t  all  lead  lead  ( T a b l e 4.0,  diagrams  (Figs.  3.3  data  plotting  F i g . 4.0, t o 3.5)  Appendix A ) .  Beca p l o t s  t h e mean v a l u e of c l u s t e r  3.  geological  Beca p r o p e r t y  deposit  has  setting  of  been c l a s s i f i e d  ( P r e t o e t a l . , 1985; it  the  pyritic  Interpretation  because  from  the The  as a s y n g e n e t i c v o l c a n o g e n i c  sulphide rich  c h e r t y bands, and  furthest  regarding  no.  3 is  However, i n  i s uncertain.  BCDM A s s e s s e m e n t R e p o r t  c o n t a i n s conformable  in cluster  deposit  7040) b e c a u s e  horizons associated with  i t occurs  w i t h i n the  same  86  Devonian  felsic  deposits  (unit  volcanic EBA).  Beca d e p o s i t f a l l s the  lead  isotope  from data  Cretaceous Zircons chord to  from  as t h e t i m e  and r e s u l t i n g  note  that  event  zircon  The D e v o n i a n  i s advocated  discordance. age o f t h i s  and h o m o g e n i z a t i o n  batholith  offers  solutions  t h a n does t h e J u r a s s i c  metamorphism.  f o r the v o l c a n i c s .  to account  subsequent 3.  greater potential  A  f o r lead  event  Therefore  of the l e a d  The C r e t a c e o u s  date i s  I t i s i n t e r e s t i n g to  t o t h e model age o f c l u s t e r  have o c c u r r e d .  a discordant  curve at p o i n t s corresponding  of c r y s t a l l i z a t i o n  the Cretaceous  remobilization  i s e p i g e n e t i c and  ( F i g . 4.0), y i e l d e d  1981).  (Preto,  loss  and  distinct  s y n g e n e t i c and D e v o n o - M i s s i s s i p p i a n .  the Concordia  Cretaceous  corresponds  s i g n a t u r e of t h e  3 , and i s m a r k e d l y  the m i n e r a l i z a t i o n  Beca p r o p e r t y  399 and 100Ma  might  that  than  intercepting  subsequent  isotopic  t h e Rea G o l d , Homestake and F o r d d e p o s i t s . These  rather  interpreted  However t h e l e a d  in cluster  indicate  from  s e q u e n c e as t h e Homestake and Rea G o l d  intrusion  lead  i n the Cretaceous of the Baldy  f o r g e n e r a t i o n of c i r c u l a t i n g  event  related  to deformation  N e v e r t h e l e s s t h e same argument a g a i n s t t h e  re-homogenization  process  the  c o m p o s i t i o n o f t h e d e p o s i t s h o s t e d by t h e same  lead  Devonian  isotopic unit  re-homogenized deposit  4.2.2) a p p l i e s  (the c o g e n e t i c d e p o s i t s of c l u s t e r to a Cretaceous  i s not l o c a t e d  the b a t h o l i t h  (see s e c t i o n  and t h i s  age.  h e r e , as  1) has n o t been  U n f o r t u n a t e l y , t h e Beca  closer  than o t h e r d e p o s i t s i n the area t o  cannot  be u s e d  to j u s t i f y  why  i t s lead  87  composition  could  have been more s i g n i f i c a n t l y  intrusion.  The m i n e r a l i z a t i o n  m i g h t be an  a f f e c t e d by t h e  epigenetic  replacement.  4.7 LEAD DATA BEYOND CLUSTER 3  Mineralization related  o f t h e June v e i n  t o a T e r t i a r y event  Tertiary  model age a l o n g  since  surrounding  it  i s based  on t h r e e d u p l i c a t e  no  analysis  from  map a r e a and  and o c c u r  Fluke deposits.  mineralization to  these  lead  dykes,  from  analysis  deposit  i n close  be s t a t i s t i c a l l y  galena.  of those  from t h e  deposits.  didaffected  I f the  the Eagle  of T e r t i a r y composition i s  remobilization  forvariations  distinguished  related  l a t e dykes d i d n o t a f f e c t  the paucity  argument a g a i n s t  spatially  (Appendix C ) .  i s o t o p i c composition  of l e a d  Spar  of lead,  structures,  zones  i n the  of the Mosquito King,  Bay  responsible  although  isotopic  and d e f o r m a t i o n a l e v e n t  another  The o n l y  has a s i m i l a r l e a d  vicinity  cross-cutting  to a  deposit,  Eocene t h e r m a l Formation,  close  t h e same  the i n t r u s i o n of these  o v e r a l l lead  from  The i s o t o p i c s i g n a t u r e  cannot  plots  lamprophyre dykes a r e widespread  the massive sulphide  Consequently, the  from  data  l a t e and  this interpretation i s that,  any o t h e r  Tertiary  i t s lead  the remodeled curve.  uncertainty  composition.  i s probably  i n the lead  a s a common  process  i s o t o p i c c o m p o s i t i o n of  88  4.8  SUMMARY  The Eagle Bay  l e a d i s o t o p i c composition  of d e p o s i t s hosted by  the  Formation i n d i c a t e s that three pulses of  m i n e r a l i z a t i o n were r e s p o n s i b l e f o r s u l p h i d e c o n c e n t r a t i o n w i t h i n the u n i t s of the Formation. identified 1  i n the Eagle Bay  with a model age  The  oldest mineralization  Formation i s represented  of Devonian.  by  cluster  This c l u s t e r c h a r a c t e r i z e d l e a d  from p o l y m e t a l l i c d e p o s i t s which are cogenetic with f e l s i c intermediate v o l c a n i c rocks of Devono-Mississippian Therefore, c l u s t e r  1 can be used to f i n g e r p r i n t  m i n e r a l i z a t i o n o c c u r r i n g i n the Eagle Bay  The  to  age.  such type of  Formation.  second p e r i o d of m i n e r a l i z a t i o n i s Upper T r i a s s i c ,  i s represented  by c l u s t e r  of the d e p o s i t s — mainly f o r t h i s study.  The  2.  and  This c l u s t e r contains almost h a l f  veins and  s t r a t i f o r m d e p o s i t s — sampled  v e i n d e p o s i t s i n d i c a t e t h a t there was  a  pulse of m i n e r a l i z a t i o n o c c u r r i n g during that p e r i o d that i s mainly  c h a r a c t e r i z e d by i n f i l l i n g  of s u i t a b l e s t r u c t u r e s .  s t r a t i f o r m d e p o s i t s w i t h i n t h i s c l u s t e r may replacement or cogenetic i n o r i g i n .  be  The  either  I f c o g e n e t i c , the part of  the u n i t which host these d e p o s i t s must be Upper T r i a s s i c r a t h e r than Cambrian as c u r r e n t l y mapped ( S c h i a r i z z a and  Preto,  since r e s s e t t i n g of the lead i s o t o p i c composition  by  1984)  89  metamorphism deposits. Bay  cannot  account  f o r the T r i a s s i c  B a s e d upon t h e u p p e r c r u s t a l  Formation,  equivalent  t h e Upper T r i a s s i c  to rocks of the Slocan  an  Group.  o u t s i d e o f and t o t h e r i g h t  uranium  cause  event  isotopic absent thermal  and i n d i c a t e Tertiary  associated  event  with i t .  of the Baldy  of T e r t i a r y  that  even  composition  2 , a r e h o s t e d by i s probably the the l a s t  3.  batholith.  from This Lead  model age, a r e m a r k e d l y  i f the Formation  no i m p o r t a n t  major  isotope data  and r e p r e s e n t e d by c l u s t e r  to the i n t r u s i o n  compositions,  Finally,  r e c o r d e d by t h e l e a d  i s mid-Cretaceous  i s related  isotopic  member o f t h e f o r m a t i o n w h i c h  of m i n e r a l i z a t i o n  study  lead  of c l u s t e r  f o r the r a d i o g e n i c s i g n a t u r e .  period this  rich  s i g n a t u r e of the Eagle  u n i t would p r o b a b l y be  Some d e p o s i t s , w h i c h have t h e i r falling  model age o f t h e s e  was a f f e c t e d  mineralizing  processes  by a were  90  5.  CONCLUSIONS  This hosted  lead  isotopic  by t h e E a g l e  Clearwater 'shale'  o f 37 m i n e r a l i z e d o c c u r r e n c e s  Bay F o r m a t i o n  i n t h e Adams P l a t e a u -  area allowed e v a l u a t i o n of the a p p l i c a b i l i t y  c u r v e o f Godwin and S i n c l a i r  Adams P l a t e a u - C l e a r w a t e r these  study  deposits plot  that  t h e model  lead  source  the c o r r e l a t i o n  peri-cratonic Barkerville  correct.  in origin,  was d e r i v e d  and i n v o l v e d I t also  Bay F o r m a t i o n  successions, particularly  from  with  other  i n t h e K o o t e n a y A r c and  f o r p r e c i s e model age  the galena-lead data  from  t h e E a g l e Bay  B e t t e r c o i n c i d e n c e o f t h e d a t a was o b t a i n e d w i t h a  remodeled curve  using  growth c u r v e of Stacey  2.OGa as d e p a r t u r e and Kramers  time  (1975).  from  The 2.OGa d e p a r t u r e of the C o r d i l l e r a n  corresponds  time  approximates  crust,  t o ages d e t e r m i n e d  the average  T h i s c u r v e has t h e  same u v a l u e as t h e ' s h a l e ' c u r v e , b u t h a s a l o w e r  formation  from  t h e E a g l e Bay F o r m a t i o n . of the Eagle  indicating  Terranes.  determination  45.35.  c o m p o s i t i o n of  T h i s shows t h a t t h e  Cordillera,  ' s h a l e ' c u r v e was i n a d e q u a t e  Formation.  isotopic  the 'shale' curve  of the Canadian  basement under  reinforced  The  is substantially  portion  (1981) t o d e p o s i t s i n t h e  The l e a d  g e n e r a l l y along  i s upper c r u s t a l  autochthonous Precambrian  area.  of t h e  w v a l u e of  the time of  and was c h o s e n  because i t  by o t h e r s f o r t h e Shuswap  91  M e t a m o r p h i c Complex (c|_. The l e a d i n the Eagle  isotopic  Duncan,  1982).  c o m p o s i t i o n of  Bay F o r m a t i o n p l o t  galena  deposits  i n three d i s t i n c t clusters  the remodeled c u r v e .  The D e v o n i a n c l u s t e r  isotopic  which c h a r a c t e r i z e  compositions  from the  1 encloses  along  lead  oogenetic  mineralization associated with Devono-Mississippian volcanic rocks.  This cluster  therefore  c a n be u s e d t o  fingerprint  p o l y m e t a l l i c v o l c a n o g e n i c d e p o s i t s h o s t e d by t h e E a g l e Formation.  Similarly,  the mid-Cretaceous  to d i s t i n g u i s h vein deposits B a l d y b a t h o l i t h and o f cluster  2 contains  interpretation  its  deposits  cannot apply  Some of  them a r e  epigenetic  related  t o j u x t a p o s i t i o n of  related  to the  satellites. of  veins,  types  3 c a n be  i n t r u s i o n of  The Upper  various  t o a l l of  cluster  Bay  so  the  Triassic  that  the d e p o s i t s  a  unique  represented.  and t h e i r f o r m a t i o n m i g h t  the F e n n e l l Formation with the  Bay F o r m a t i o n , o r t o a y e t u n d e f i n e d e v e n t w h i c h a f f e c t e d area  i n the T r i a s s i c .  Plateau, during  deposits  is  i n t e r p r e t a t i o n of  i n that  however,  oogenetic the  be  Eagle the  The s t r a t i f o r m d e p o s i t s on t h e Adams  which a l s o p l o t  such e v e n t ,  used  if  cluster,  a l s o may have  formed  the m i n e r a l i z a t i o n i n these  w i t h the Cambrian u n i t EBG, the l e a d m o d e l age  imply  stratigraphic  r e c o n s i d e r a t i o n and t h e u n i t EBG s h o u l d be s u b d i v i d e d i n t o two distinct  members  ( u n i t T-EBG) age  of  C a m b r i a n ( u n i t E B G ) , and o f Upper  t o accommodate  the  data.  Triassic  92  The  galena  illustrates  Recognition  developed  o f t h e common  here  further  l e a d method i n  mineral deposits within a given region. of a lead  hosted  implications which  i s o t o p e study  the a p p l i c a b i l i t y  categorizing  deposits  lead  isotopic  field  that  ' f i n g e r p r i n t s ' the  by t h e E a g l e Bay F o r m a t i o n  has i m p o r t a n t  f o r e x p l o r a t i o n programs by p r o v i d i n g a c u r v e  from  t h e age and g e n e r a l g e n e s i s o f any new m i n e r a l i z e d  discoveries assessed.  i n t h e Adams P l a t e a u - C l e a r w a t e r The d i s t i n c t i o n  cannot  be s e t t l e d  lead.  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P i l b a r a galenas: P r e c i s e i s o t o p i c assay of the o l d e s t A u s t r a l i a n leads; model ages and g r o w t h - c u r v e i m p l i c a t i o n s . M i n e r a l i u m D e p o s i t a , 16, pp. 7-30. ROSS, J.V.,and FILLIPONE, J.A. i n p r e s s . D e t a i l s o f a c o n v e r g e n t zone a s s o c i a t e d w i t h a c c r e t i o n of L a t e P a l e o z o i c t o E a r l y M e s o z o i c a l l o c h t h o n s t o t h e w e s t e r n m a r g i n of N o r t h A m e r i c a , c e n t r a l B r i t i s h Columbia.  ROSS, J.V. 1974. A T e r t i a r y t h e r m a l e v e n t i n S o u t h - C e n t r a l B r i t i s h C o l u m b i a . C a n a d i a n J o u r n a l of E a r t h S c i e n c e , 11, pp. 1116-1121 . RUSSELL, R.D.,and FARQUHAR, R.M. 1960. L e a d I n t e r s c i e n c e , New Y o r k e d . , 243 p.  Isotopes i n Geology.  SATO, K.,and SASAKI, A. 1976. L e a d i s o t o p i c e v i d e n c e on t h e g e n e s i s of p r e - C e n o z o i c s t r a t i f o r m s u l p h i d e d e p o s i t s i n J a p a n . G e o c h e m i c a l J o u r n a l , 10, pp. 197-203. SATO, K.,DELEVAUX, M.H.,and DOE, B.R. 1981. L e a d i s o t o p e measurements o r e s , i g n e o u s and s e d i m e n t a r y r o c k s from t h e Kuroko m i n e r a l i z a t i o n a r e a . G e o c h e m i c a l J o u r n a l , 15, pp. 135-140. SCHIARIZZA, P.A. 1986. G e o l o g y of t h e E a g l e Bay F o r m a t i o n b e t ween t h e R a f t and B a l d y B a t h o l i t h s (82M/5,11,12). B.C. M i n i s t r y o f E n e r g y , M i n e s & P e t . R e s . G e o l o g i c a l F i e l d w o r k 1985, paper 1986-1, pp. 89-94. SCHIARIZZA, P.A. 1986b. G e o l o g y o f t h e Vavenby a r e a . NTS 82M5,11,12. B.C. M i n i s t r y o f E n e r g y , M i n e s & P e t . R e s . Open f i l e . SCHIARIZZA,  P.A.,and  PRETO, V.A.  1984. G e o l o g y  o f t h e Adams  101  Plateau-Clearwater Res. Map Nb. 56.  area.  B.C M i n i s t r y o f E n e r g y , Mines & P e t .  SCHIARIZZA, P.A. 1982. C l e a r w a t e r a r e a (82M/12W; 92P/8E,9E). B.C. M i n i s t r y o f E n e r g y , M i n e s & P e t . R e s . G e o l o g i c a l F i e l d work 1981, p a p e r 1982-1, pp. 59-67.  SCHIARIZZA, P.A. 1981. C l e a r w a t e r a r e a (82M/12W; 92P/8E,9E). B.C. M i n i s t r y o f E n e r g y , M i n e s & P e t . R e s . G e o l o g i c a l F i e l d work 980, paper 1981-1, pp. 159-164.  SLAWSON, W.F. 1983. I s o t o p i c c o m p o s i t i o n o f l e a d from a p a l e o i s l a n d a r c : Shasta C a l i f o r n i a . Canadian J o u r n a l of Earth S c i e n c e s , 20, pp. 1521-1527.  SOLOMON, M. 1976. V o l c a n i c m a s s i v e s u l p h i d e d e p o s i t s and t h e i r h o s t r o c k s : A r e v i e w and e x p l a n a t i o n , i n Handbook on s t r a t a bound and s t r a t i f o r m o r e d e p o s i t s , K.H. Wolf e d . E l s e v i e r Amsterdam, V o l . 2, pp. 21-50. STACEY, J . S . , a n d KRAMERS, J.D. 1975. A p p r o x i m a t i o n o f t e r r e s t r i a l l e a d i s o t o p e e v o l u t i o n by a two s t a g e m o d e l . E a r t h and Planetary Sciences L e t t e r s , 26, pp. 207-221. STACEY, J.S.,DELEVAUX, M.H.,and ULRICH, T . J . 1969. Some t r i p l e f i l a m e n t l e a d i s o t o p e r a t i o measurements and an a b s o l u t e growth c u r v e f o r s i n g l e - s t a g e l e a d s . E a r t h and P l a n e t a r y S c i e n c e L e t t e r s , 6, pp. 15-25. STANTON,R.L.,and RUSSELL, R.D. 19 59. Anomaleous l e a d s and t h e emplacement o f l e a d s u l p h i d e o r e s . E c o n o m i c G e o l o g y , 54, pp. 588-607.  STEIGER, R.W.,and JAGER, E. 1977. Subcommission on geochronology convention on the use of decay constants i n geo and cosmochronology. E a r t h and P l a n e t a r y Science L e t t e r s , 36, p. 359. STRUIK, L.C. 1986. I m b r i c a t e d t e r r a n e s o f t h e C a r i b o o g o l d b e l t w i t h c o r r e l a t i o n s and i m p l i c a t i o n s f o r t e c t o n i c s i n s o u t h e r n B r i t i s h C o l u m b i a . C a n a d i a n J o u r n a l o f E a r t h S c i e n c e s , V o l . 23,  1 02  pp.  1 047-1061 .  TATSUMOTO, M.,KNIGHT, J.R.,and ALLEGRE C . J . 1973. Time d i f f e r r e n c e s i n t h e f o r m a t i o n o f m e t e o r i t e s as d e t e r m i n e d f r o m t h e r a t i o o f l e a d 207 t o l e a d 206. S c i e n c e , 180, p . 1279. UGLOW, W.L. 1922. G e o l o g y o f t h e n o r t h Thompson V a l l e y mapa r e a , B r i t i s h C o l u m b i a . G e o l o g i c a l S u r v e y o f Canada, Summary R e p o r t 1921, P a r t A. p p . 72-106. WANLESS, R.K, STEVENS,R.D.,LACHANCE,G.R.,and RIMSAITE, J.Y.H. 1966. Age d e t e r m i n a t i o n s and g e o l o g i c a l s t u d i e s : K-Ar i s o t o p i c a g e s , R e p o r t 5. G e o l o g i c a l S u r v e y o f Canada, p a p e r 65-17, 101 p .  WATSON, P.H. 1981. G e n e s i s and z o n i n g o f s i l v e r - g o l d v e i n s i n the B e a v e r d e l l a r e a , s o u t h - c e n t r a l B r i t i s h C o l u m b i a . U n p u b l i s h e d M.Sc. t h e s i s U n i v e r s i t y o f B r i t i s h C o l u m b i a , 156 p. WHEELER, J.O,and GABRIESLE, H. 1972. The C o r d i l l e r a n s t r u c t u r a l p r o v i n c e s . I n R.A. P r i c e and R.J.W. D o u g l a s e d . V a r i a t i o n s i n t e c t o n i c s t y l e s i n Canada. G e o l o g i c a l A s s o c i a t i o n o f Canada S p e c i a l p a p e r 11, pp. 1-18. YORK, D. 1969. L e a s t s q u a r e s f i t t i n g o f a s t r a i g h t l i n e w i t h c o r r e l a t e d e r r o r s . E a r t h and P l a n e t a r y S c i e n c e L e t t e r s , 5, pp. 320-324. ZARTMAN, R.E. 1974. L e a d i s o t o p i c p r o v i n c e s i n t h e C o r d i l l e r a o f t h e w e s t e r n U n i t e d S t a t e s and t h e i r g e o l o g i c s i g n i f i c a n c e . E c o n o m i c G e o l o g y , 69, pp. 792-805.  103  APPENDIX A  ADAMS PLATEAU-CLEARWATER DEPOSIT DESCRIPTIONS  AREA  The f o l l o w i n g d e s c r i p t i o n s c o n s t i t u t e a b r i e f summary o f l i t e r a t u r e r e v i e w on t h e d e p o s i t s o f t h e Adams P l a t e a u C l e a r w a t e r a r e a augmented by o b s e r v a t i o n s , and i n some c a s e d e t a i l e d work, made by t h e w r i t e r i n t h e summers 1984 and 1985. The c o m p i l a t i o n map o f S c h i a r i z z a e t a_l.(1984) h a s been used t o a s s i g n l i t h o l o g i c names t o h o s t u n i t s o f t h e d e p o s i t s . The a b b r e v i a t e d names f o r t h e s e u n i t s (and s u b u n i t s ) a p p e a r i n parentheses. D e s c r i p t i o n s o f t h e s e u n i t s and s u b u n i t s a p p e a r on S c h i a r i z z a ' s map ( o p . c i t . ) and i n BCDM f i e l d w o r k p a p e r s from S c h i a r i z z a a n d / o r P r e t o on t h e Adams P l a t e a u C l e a r w a t e r area between 1978 and 1986.  Table A.1: Mineral deposits in the Adams Plateau-Clearwater Area Deposit Name ADAMS PLATEAU AREA Beca Lucky Coon Spar Mosquito king BC Zn 1 Crowfoot Mtn Ford property Silver king Silver king-Queen Pet Red Mineral Claims JOHNSON LAKE AREA Agate Bay Twin Mountain Art Homestake Rea Gold  Deposit Type  Stratabound Stratiform/Remobilized Stratiform/Remobilized Stratiform/Remobilized Disseminations Replacement Volcanogenic Vein Vein Vein Vein  Mineralized pods Vein Vein Volcanogenic/polymetal. Volcanogenic/polymetal.  BARRIERE LAKES AREA Birk Creek Showings Enargite Fortuna White Rock June/Kajun Broken Ridge Leemac  S t r a t i f orm/Volcanogenic Vein Vein Vein Vein Disseminations Vein  VAVENBY-CLEARUATER AREA Chu-Chua Foghorn Rexspar Mt McClennan Vavenby Ps-75-185 Sonja Birch Island Tindal  Volcanogenic/cyprus Vein Volcanogenic/Uranion Replacement Vein Vein Vein Vein Vein  1 05  ADAMS PLATEAU AREA: BECA: A l s o known a s : Q u e s t Group, L u c k y S t r i k e , Rhode I s l a n d , L a k e v i e w - J o e , Tom M i n f i l e number: 082M-054,055 M i n e r a l I n v e n t o r y number: 82M4-PB4 Map number: 007; L a t . 51.050N l o n g . 119.710W Production,  as  listed  in Minfile:  5 t o n n e s of o r e  (1926):  31 g Au 2,395 g Ag 1 , 496 kg Pb  L o c a t i o n : The Beca p r o p e r t y on t h e s h o r e of Adams L a k e , due e a s t of Squaam Bay i s d i r e c t l y a c c e s s i b l e by b o a t . A s w i t c h b a c k r o a d d r o p p i n g 1,800m from N i k w i k w i a l a k e on t h e w e s t e r n edge of t h e p l a t e a u , a l s o l e a d s to the p r o p e r t y . H o s t r o c k : The a r e a c o n s i s t s of a r e p e t i t i v e s u c c e s s i o n of a n d e s i t i c t o r h y o l i t i c v o l c a n i c r o c k s and a s s o c i a t e d q u a r t z i t i c and a r g i l l a c e o u s m e t a - s e d i m e n t a r y r o c k s ( E B A ) . The r o c k s a r e metamorphosed t o g r e e n s c h i s t f a c i e s and show a h i g h d e g r e e of s c h i s t o s i t y t h a t s t r i k e s a b o u t N85W and d i p s 25 t o 45 d e g r e e s north. The more f e l s i c phase has c l e a r l y i n v a d e d a n d e s i t i c r o c k s w h i c h a r e p r e s e r v e d as x e n o l i t h s i n t h e f e l s i c r o c k s . S m a l l g r a n i t i c i n t r u s i o n s i m m e d i a t l y s o u t h of t h e p r o p e r t y boundary produced a thermal metamorphic a u r e o l e t h a t o v e r p r i n t s r e g i o n a l low g r a d e metamorphism. The c h e m i c a l s i m i l a r i t y between t h e g r a n i t i c r o c k s and t h e f e l s i c v o l c a n i c r o c k s may i n d i c a t e a comagmatic r e l a t i o n s h i p between t h e s e two r o c k t y p e s . M i n e r a l i z a t i o n : The two m i n e r a l i z e d a r e a s f o u n d on t h e p r o p e r t y are a s s o c i a t e d w i t h p y r i t i c c h e r t y bands. The s u l p h i d e s o c c u r as f i n e g r a i n e d c o n f o r m a b l e l e n s e s c o n t a i n i n g p o r p h y r o b l a s t s o f a r s e n o p y r i t e and l o c a l l a y e r s o f s p h a l e r i t e . Locally, altered r h y o l i t e i s l a c e d w i t h n a r r o w (1 t o 25mm), c l o s e l y s p a c e d q u a r t z v e i n s w h i c h a r e s p o r a d i c a l l y m i n e r a l i z e d w i t h g a l e n a and more r a r e l y with s p h a l e r i t e . Sample d e s c r i p t i o n : Samples a r e a f i n e g r a i n e d m i x t u r e of p y r i t e , c h a l c o p y r i t e , g a l e n a , and s p h a l e r i t e a s s o c i a t e d w i t h c a l c i t e and minor q u a r t z . The s a m p l e s were c o l l e c t e d from m a s s i v e s u l p h i d e r i c h l a y e r s w i t h i n the s c h i s t b e s i d e the o l d a d i t s near the l a k e shore. References:  BCDM ASS BCDM GEM  RPT 6680, 7040. 1970 p. 314.  106  LUCKY COON: A l s o known as Mc G i l l i v a r y g r o u p , E l s i e , S p e e d w e l l , K i n g T u t . M i n f i l e number: 082M-012 t o 015 M i n e r a l I n v e n t o r y number: 82M4-PB4 t o PB7 Map number: 018; L a t . 51.070N L o n g . 119.600W Grades,  as l i s t e d i n M i n f i l e : T o t a l d e p o s i t ( i n d i c a t e d 68,040 t o n n e s , c u t o f f u s e d : 296.0 g / t Ag 7.1 % Pb 4.8 % Zn  P r o d u c t i o n , as l i s t e d i n M i n f i l e : from L u c k y Coon, 496  tonnes of o r e 274 228,669 62,03 3 41,367 114  : from E a s t  Lehmi,  30  g g kg kg  (1976-1977):  Au Ag Pb Zn Cd  tonnes of ore 31 35,146 8,330 2,393  L o c a t i o n : Lucky Coon i s 1,830m. The p r o p e r t y i s Scotch Creek a c r o s s the s o u t h end o f Adams Lake  g kg kg kg kg  1972):  (1956):  Au Ag Pb Zn  on t h e Adams P l a t e a u a t an e l e v a t i o n o f a c c e s s i b l e by l o g g i n g r o a d s e i t h e r f r o m p l a t e a u t o t h e o l d open p i t , o r from t h e t o w i t h i n 2km o f t h e p r o p e r t y .  H o s t Rock: The m i n e r a l i z a t i o n i s a s s o c i a t e d w i t h b l a c k and d a r k brown s i l i c e o u s and g r a p h i t i c p h y l l i t e , and w i t h p h y l l i t i c l i m e s t o n e (EBG). Wide bands o f f i n e - g r a i n e d s e r i c i t i z e d q u a r t z i t e , i n t e r l a y e r e d w i t h s m a l l e r c h l o r i t e - c a l c i t e r i c h bands occur close to s u l p h i d e - r i c h horizons. These metasedimentary u n i t s a r e f o l d e d by t h e N i k w i k w a i a L a k e s y n f o r m and a r e s u r r o u n d e d by g r e e n s c h i s t s t h a t a r e d e r i v e d f r o m m a f i c f l o w s and tuffs. Q u a r t z f e l d s p a r p o r p h y r y dykes c r o s s c u t p a r t of the s o u t h e r n l i m b o f t h e s y n f o r m and show e v i d e n c e o f s u b s e q u e n t folding. B a s i c dykes a r e a l s o p r e s e n t b u t a r e n o t w e l l e x p o s e d . S t r u c t u r e : I s o c l i n a l and a s y m m e t r i c f o l d s , e s p e c i a l l y w e l l exposed i n the n o r t h e r n p i t , demonstrate the prominent r o l e of the s t r u c t u r e i n c o n t r o l l i n g the d i s t r i b u t i o n of the s u l p h i d e s . I n s u c h f o l d s , s u l p h i d e beds 25cm t h i c k on t h e l i m b s r e a c h a t h i c k n e s s o f 45cm i n t h e h i n g e zone. O r i g i n a l t e x t u r e i n the s u l p h i d e h o r i z o n s has been o b l i t e r a t e d by t h e d e f o r m a t i o n .  107  Mineralization: S i l v e r , l e a d and z i n c s u l p h i d e s a r e g e n e r a l l y r e s t r i c t e d t o a s p e c i f i c s t r a t i g r a p h i c h o r i z o n ( s i l i c e o u s and g r a p h i t i c p h y l l i t e s , p h y l l i t i c limestones) that i s generally c o n t i n u o u s a l o n g s t r i k e f o r 2000m. I n d e t a i l , however, t h e s u l p h i d e zones a r e d i s c o n t i n u o u s due t o r e m o b i l i z a t i o n and d i s r u p t i o n d u r i n g f o l d i n g ( D i c k i e , 1 9 8 5 ) . The s u l p h i d e s a r e f i n e - g r a i n e d a n d o c c u r a s bands, from 15cm t o 1m wide s e p a r a t e d by 30 t o 90cm o f s i l i c e o u s p h y l l i t e , o r a s v e i n s i n s e r i c i t i c schists. The m i n e r a l i z a t i o n c o n s i s t s o f a r s e n o p y r i t e , p y r i t e , s p h a l e r i t e , g a l e n a , a r g e n t i t e and a l i t t l e t e t r a h e d r i t e . The r a t i o of the d i f f e r e n t sulphides throughout the d e p o s i t i s v a r i a b l e ; t h e a r s e n o p y r i t e c o n t e n t v a r i e s f r o m 1 t o 25% (commonly diamond s h a p e d g r a i n s a r e l o c a l l y e x t e n s i v e l y r e p l a c e d by s p h a l e r i t e and g a l e n a ) . The p y r i t e c a n c o m p r i s e a s much a s 75% o f t h e s u l p h i d e zone b u t i s o f t e n embayed a n d / o r r e p l a c e d by s p h a l e r i t e and g a l e n a ; however, e u h e d r a l u n b r o k e n p y r i t e c r y s t a l s ( p r o b a b l y f o r m e d by r e c r y s t a l l i z a t i o n ) do o c c u r . The s p h a l e r i t e and g a l e n a a r e i n t i m a t e l y a s s o c i a t e d . Embayed i s l a n d s o f s p h a l e r i t e w i t h c u s p - s h a p e b o r d e r s a r e common. Sample d e s c r i p t i o n : M a s s i v e s u l p h i d e samples were c o l l e c t e d from the s e r i c i t i c s c h i s t u n i t i n t h e o l d p i t number 1. The samples c o n s i s t o f s m a l l b l e b s o f g a l e n a a s s o c i a t e d w i t h q u a r t z and c a l c i t e i n a f i n e - g r a i n e d m a t r i x composed m a i n l y o f s p h a l e r i t e and p y r i t e . References:  BCDM ASS. RPT. 11,521. BCDM MMAR 1936 pp. D41-D43. BCDM MMAR 1930 pp. A184-A186. DICKIE, G . J . 1985.  108  SPAR:  A l s o known a s : Ex 1, B e l M i n f i l e number: 082M-017, 018 M i n e r a l I n v e n t o r y number: 82M4-PB2, PB5 t o PB7 Map number: 027; L a t . 51.060N L o n g . 119.540W Production,  as  listed  i n M i n f i l e : 274 t o n n e s o f o r e , (1952, 1953, 1955, 435 249,383 4,953,594 891,766 291  g g kg kg kg  1976):  Au Ag Pb Zn Cu  L o c a t i o n : The S p a r d e p o s i t i s on t h e s o u t h e a s t e r n edge of the Adams P l a t e a u l e s s t h a n 2km west of t h e M o s q u i t o K i n g d e p o s i t . I t i s a c c e s s i b l e by the l o g g i n g r o a d s p a r a l l e l t o S c o t c h Creek. H o s t Rock: M i n e r a l i z a t i o n i s h o s t e d by f o l d e d l i m y p h y l l i t e s a s s o c i a t e d w i t h m i n o r s e r i c i t e q u a r z t i t e s , l i m e s t o n e and c h l o r i t i c m e t a - v o l c a n i c s (EBGs). The s u l p h i d e h o r i z o n s and the h o s t r o c k s a r e e n c l o s e d w i t h i n t h e same i n t e r m e d i a t e t o m a f i c v o l c a n i c and v o l c a n i c l a s t i c s e q u e n c e s e n c o u n t e r e d a t t h e M o s q u i t o K i n g and L u c k y Coon d e p o s i t s . Mineralization i s also c u t by s m a l l f i n e - g r a i n e d d i o r i t e and g r a n i t e p o r p h y r y d y k e s . S t r u c t u r e : The r o c k s i n t h e v i c i n i t y o f t h e d e p o s i t a r e s t r o n g l y f o l i a t e d , have a g e n e r a l e a s t - w e s t s t r i k e , and d i p g e n t l y n o r t h w a r d . S t r a t a show d r a g f o l d i n g and c r e n u l a t i o n c l e a v a g e ; f o l d axes s t r i k e S600w w i t h low p l u n g e ( t h e c r e s t p l u n g e s 100sw). Two s e t s o f f r a c t u r e s c u t t h e r o c k s : one dipping s t e e p l y n o r t h - s o u t h and t h e o t h e r d i p p i n g more s h a l l o w l y dipping east-west. The n o r t h - s o u t h s e t seems t o have a c t e d as a c h a n n e l way f o r m i n e r a l i z i n g s o l u t i o n s i n c e f a i r l y m a s s i v e f i n e - g r a i n e d s p h a l e r i t e i s found i n the f o l d e d zones d i r e c t l y above such f r a c t u r e s ( D i c k i e , 1985). The e a s t - w e s t s e t t e r m i n a t e s a b r u p t l y some m i n e r a l i z e d h o r i z o n s and t h u s may be p a r t of a l a t e f r a c t u r i n g e v e n t . M i n e r a l i z a t i o n : S t r a t i f o r m s u l p h i d e masses o c c u r as f o l d e d e l o n g a t e d b o d i e s ( e x t e n d i n g o v e r 400m). The m i n e r a l i z a t i o n d i s t r i b u t i o n does not a p p e a r t o be c o n f i n e d t o o n l y one l a y e r . However t h e m i n e r a l i z a t i o n i s a p p a r e n t l y s t r a t a b o u n d and was o r i g i n a l l y deposited within a s i l i c e o u s unit. T h i s u n i t has been f o l d e d and metamorphosed, r e s u l t i n g i n t h e m i g r a t i o n and c o n c e n t r a t i o n of t h e s u l p h i d e m i n e r a l s a l o n g t h e c r e s t s o f f o l d s o r c r u m p l e d zones i n t h e e n c l o s i n g s e r i c i t i c s e q u e n c e ( D i c k i e , 1 985 ) .  109  The s u l p h i d e h o r i z o n s a r e composed o f m a s s i v e l a y e r e d g a l e n a b o r d e r e d by a f r i n g e zone o f g a l e n a , s p h a l e r i t e , p y r i t e , p y r r h o t i t e and c h a l c o p y r i t e . M i n o r amounts o f t e t r a h e d r i t e , a r s e n o p y r i t e and a r g e n t i t e a l s o o c c u r . The bands o f m a s s i v e m i n e r a l i z a t i o n (40cm t h i c k ) a r e s e p a r a t e d by s e r i c i t i z e d argillite. Sample d e s c r i p t i o n : Samples were c o l l e c t e d from t h e main o l d a d i t s f r o m w h i c h most o f t h e m i n e r a l s were e x t r a c t e d i n t h e 1950's. F i n e - g r a i n e d g a l e n a i s a s s o c i a t e d w i t h s p h a l e r i t e and p y r i t e i n a quartz carbonate matrix. A v e i n c o n t a i n i n g abundant f l u o r i t e was a l s o s a m p l e d . R e f e r e n c e s : BCDM MMAR 1953 pp. 102-103. HAINSWORTH, W.G. 1973. U n p u b l i s h e d Giant M e t a l l i c Mines. JAMES, D.H. 1949.  report  on t h e  11 0  MOSQUITO KING: A l s o known a s : Oro, K i n g T u t , G a r n e t M i n f i l e number: 082M-016, 140 M i n e r a l I n v e n t o r y number: 82M4-AG2, CU2 Map number: 025; L a t . 51.060N L o n g . 119.520W Reserves,  as  Production,  listed  as  in Minfile  listed  40,824 t o n n e s 1.25 g / t Au 21.70 g / t Ag 10.0 % Pb 8.5 % Zn  @  (Ind.  1981):  in Minfile  419 t o n n e s o f o r e (1972-73, 1 9 7 6 ) : 219 g Au 232,154 g Ag 22,721 kg Pb 18,328 kg Zn  L o c a t i o n : The M o s q u i t o K i n g p r o p e r t y i s l o c a t e d a t an a p p r o x i m a t e e l e v a t i o n of 1,750m on a r i d g e on t h e Adams P l a t e a u . A l o g g i n g r o a d between N i k w i k w a i n G o l d C r e e k and K w i k o i t C r e e k l e a d s to the p r o p e r t y . H o s t Rock: S u l p h i d e l e n s e s a r e e n c l o s e d w i t h i n i n t e n s i v e l y s i l i c i f i e d beds o f a r g i l l i t e s and q u a r t z s e r i c i t e r o c k s . T h e s e c l a s t i c r o c k s a r e p a r t of a p r e d o m i n a n t l y m a f i c v o l c a n i c s u c c e s s i o n (EBGs). These u n i t s have been metamorphosed t o g r e e n s c h i s t f a c i e s and c o n t a i n a b u n d a n t c h l o r i t e and s e r i c i t e . S i l i c i f i c a t i o n and b l e a c h i n g i s u b i q u i t o u s i n t h e l i m y a r g i l l i t e s and i n t h e q u a r t z i t e , but n o t i n t h e g r e e n s c h i s t . The s e q u e n c e i s c u t by a n d e s i t e and h o r n b l e n d e p o r p h y r y d y k e s w h i c h a r e s i m i l a r t o t h o s e o c c u r r i n g on t h e Lucky Coon p r o p e r t y . S t r u c t u r e : F o l d s on t h e p r o p e r t y h a v e a p r e d o m i n e n t e a s t - w e s t t r e n d but a x e s s t r i k i n g n o r t h - s o u t h a r e n o t uncommon; d r a g - f o l d i n g i s u b i q u i t o u s i n most e x p o s u r e s . J o i n t s and s m a l l n o r t h s t r i k i n g f a u l t s seem t o c o n t r o l , a t l e a s t l o c a l l y , t h e mineral d i s t r i b u t i o n . M i n e r a l i z a t i o n : A t t h e main showing m i n e r a l i z a t i o n v a r i e s i n t h i c k n e s s from 60cm t o 3.5m ( a v e r a g e 1.5m). I t c o n s i s t s of s e v e r a l t h i n , c l o s e l y s p a c e d b e d s composed o f b l a c k s p h a l e r i t e , g a l e n a , p y r i t e , c h a l c o p y r i t e and f i n e - g r a i n e d p y r r h o t i t e w h i c h a r e more or l e s s c o n c o r d a n t w i t h t h e e n c l o s i n g h o s t . Lower i n t h e s u c c e s s i o n , beds h a v e been m i n e r a l i z e d w i t h i r o n s u l p h i d e s ( m a i n l y p y r r h o t i t e ) and m i n o r s p h a l e r i t e . P y r r h o t i t e and p y r i t e r i c h l e n s e s (up t o 60cm w i d e ) a r e e x t e n s i v e i n t h e l i m y argillites. Disseminated p y r i t e a l s o occurs along bedding p l a n e s and i n f r a c t u r e s a s s o c i a t e d w i t h s i l i c i f i e d z o n e s . M i n e r a l i z e d b e d s can be t r a c e d o v e r 915m a l o n g a N700E s t r i k e  111  but they a r e n o t u n i f o r m l y o r c o n t i n u o u s l y d i s t r i b u t e d . Veins of g a l e n a and s p h a l e r i t e o c c u r l o c a l l y i n t h e s c h i s t s and i n t h e limy beds. M a g n e t i t e and s e c o n d a r y c o p p e r m i n e r a l s a r e l o c a l l y abundant i n t h e m a f i c v o l c a n i c s . Minor m i n e r a l i z a t i o n a l s o o c c u r s a s s o c i a t e d w i t h t h e p o r p h y r y d y k e s (James, 1 9 4 9 ) . Sample d e s c r i p t i o n : W e l l c r y s t a l l i z e d b u t d e f o r m e d g a l e n a i n a q u a r t z and c a l c i t e m a t r i x c o n t a i n i n g a m i n o r amount o f p y r i t e and s p h a l e r i t e i s c h a r a c t e r i s t i c o f t h e main m i n e r a l i z a t i o n . The samples come from t h e main m i n e r a l i z e d a r e a o f t h e d e p o s i t i n t h e open o l d w o r k i n g s . G a l e n a was a l s o c o l l e c t e d from c r o s s - c u t t i n g v e i n s near a dyke. References:  BCDM ASS RPT 45, 7 0 1 9 . BCDM MMAR 1949 p p . A134-136. BCDM MMAR 1930 p p . A186-188. DICKIE, G . J . 1985. JAMES, D.H. 1949.  11 2  BC ZN 1: A l s o known a s : Cu 1, Cu 5 M i n f i l e number: 082M-138, 139 M i n e r a l I n v e n t o r y number: 82M4-CU1, ZN2 Map number: 022; L a t . 51.01 ON L o n g . 1 1 9.520W Grades,  as l i s t e d i n M i n f i l e : I n d i c a t e d : 148,000 t o n n e s Possible: 272,000 t o n n e s @ 0.19 % Cu Reserves: 326,000 t o n n e s @ 0.35 % Cu 38 G/t 6 % Pb 2.41 % Zn 0.19 % Cu 0.14 % Mo  L o c a t i o n : T h i s m i n e r a l i z e d o c c u r r e n c e i s a b o u t 5.5km s o u t h o f t h e M o s q u i t o K i n g d e p o s i t n e a r t h e l o c a l l y named C h i n a C r e e k . I t i s a c c e s s i b l e from one o f t h e numerous l o g g i n g r o a d s on t h e Adams P l a t e a u . H o s t Rock: A r g i l l a c e o u s p h y l l i t e s a r e i n t e r c a l a t e d w i t h l i m y and s i l i c e o u s h o r i z o n s i n t e r b e d d e d w i t h abundant g r e e n s t o n e d e r i v e d from m a f i c v o l c a n i c s and v o l c a n o c l a s t i c s (EBG). The s e q u e n c e i s i n t r u d e d by a s e r i e s o f m i n o r d i a b a s i c d y k e s and s i l l s . One dyke sampled c o n s i s t s o f h o r n b l e n d e , q u a r t z , a n d r a d i t e and minor c l i n o p y r o x e n e , c l i n o z o i s i t e , c h l o r i t e and p l a g i o c l a s e . S c h i s t o s i t y o f t h e h o s t r o c k s t r i k e s e a s t - n o r t h e a s t and d i p s moderately t o the northwest. M i n e r a l i z a t i o n : A s t r a t i f o r m zone c o n t a i n s d i s s e m i n a t e d s p h a l e r i t e and g a l e n a w i t h m i n o r p y r r h o t i t e and l o c a l l y a b u n d a n t magnetite. Some z o n e s o f h i g h i r o n c o n t e n t y i e l d good Cu and Au values. One zone may be c o n t i n o u s f o r o v e r 510m; i t h a s a w i d t h o f as much as 1.65m. Sample d e s c r i p t i o n : F i n e - g r a i n e d s p h a l e r i t e and minor g a l e n a disseminated i n h i g h l y c h l o r i t i c s c h i s t i s c h a r a c t e r i s t i c of the mineralization. References:  BCDM ASS RPT 5132 BCDM GEM 1978, p. E 1 0 1 . BCDM GEM 1974, p . 95.  11 3  CROWFOOT MOUNTAIN: A l s o known a s : F l u k e , S a u l M i n f i l e number: 082M-104, 105 Map number: 032; L a t . 51.060N G r a d e : c o m p o s i t e sample, (From ASS.RPT.)  gross  L o c a t i o n : The F l u k e c l a i m s 16km n o r t h of Magma Bay on a r e a c c e s s i b l e by f o r e s t r y  Long. average:  119.250W 0.34 g / t Au 170.0 g / t Ag 0.1 % Cu 5.0 % Pb 8.0 % Zn 0.18 % Sn  on C r o w f o o t M o u n t a i n a r e a p p r o x i m a t l y t h e n o r t h s h o r e o f Shuswap L a k e , and roads.  H o s t Rock: M i n e r a l i z a t i o n i s h o s t e d by p h y l l i t i c m a r b l e and a l t e r e d l i m e s t o n e a s s o c i a t e d w i t h p h y l l i t e , q u a r t z i t e and g r e e n s t o n e s i m i l a r t o t h o s e f o u n d i n t h e o t h e r d e p o s i t s on t h e P l a t e a u (EBG). T h e s e r o c k s a r e s t r o n g l y f o l i a t e d and l i n e a t e d . The a r e a i s i n t r u d e d by an enormous number o f d y k e s , s i l l s and s m a l l i r r e g u l a r b o d i e s o f g r a n i t i c and d i a b a s i c r o c k s . S i l i c i f i c a t i o n i s e x t e n s i v e i n the v i c i n i t y of the s u l p h i d e r i c h zones. S t r u c t u r e : I n t e n s e d r a g f o l d i n g , d i s r u p t i o n o f l i m y h o r i z o n s and g r e e n s c h i s t f a c i e s i n the m e t a - v o l c a n i c r o c k s are i n d i c a t i o n s t h a t t h e a r e a has t h e same d e f o r m a t i o n a l c h a r a c t e r i s t i c s as t h e r e s t o f t h e Adams P l a t e a u . S t r u c t u r a l d e t a i l s of the d e f o r m a t i o n i n t h e v i c i n i t y o f t h e d e p o s i t a r e n o t known. M i n e r a l i z a t i o n : M i n e r a l i z a t i o n has been d e s c r i b e d as s u l p h i d e replacement i n bands o f l i m e s t o n e and m a r b l e . On a l a r g e s c a l e the s u l p h i d e s are c o n f i n e d t o h o r i z o n s w i t h i n the l i m e s t o n e , but the d i s t r i b u t i o n of the s u l p h i d e s i s h i g h l y e r r a t i c . G a l e n a and s p h a l e r i t e o c c u r i n pods as w e l l as i n d i s s e m i n a t i o n s throughout the rock. S u l p h i d e s are a l s o found i n v e i n s c u t t i n g c h l o r i t i c schist. T h e s e v e i n s s t r i k e i n t h e same d i r e c t i o n as t h e main f o l i a t i o n ( s t r i k i n g N400N and d i p p i n g m o d e r a t e l y northwestward) but d i p i n the o p p o s i t e d i r e c t i o n . Veins are unevenly m i n e r a l i z e d w i t h g a l e n a , p y r i t e , s p h a l e r i t e and c h a l c o p y r i t e . Sample d e s c r i p t i o n : B l e b s o f c a l c i t e , p y r i t e , g a l e n a and s p h a l e r i t e p l u s m i n o r q u a r t z i n l a m i n a t e d b u t c o n t o r t e d and d i s c o n t i n u o u s l i m e s t o n e l e n s e s were s a m p l e d on t h e p r o p e r t y . V e i n m i n e r a l i z a t i o n c l o s e t o a l a m p r o p h y r e d y k e was a l s o sampled. References:  BCDM ASS  RPT  609,  3821,  4031,  6230,  6857.  11 4  FORD PROPERTY: Map number: 038;  Lat.  51.000N  L o n g . 119.600w  L o c a t i o n : The F o r d p r o p e r t y i s c e n t r e d Woolford Creek. Access i s f a c i l i t a t e d roads.  n e a r t h e head of by a n e t w o r k o f l o g g i n g  H o s t Rock: The main r o c k t y p e s i n t h e a r e a a r e s e r i c i t e q u a r t z p h y l l i t e and s e r i c i t e f e l s p a r q u a r t z p h y l l i t e c o n t a i n i n g a b u n d a n t medium t o f i n e - g r a i n e d a n g u l a r c l a s t s ( u n i t EBA). It i s l i k e l y that these rocks are a l t e r e d intermediate to f e l s i c tuffs. The u n i t s have a f r a g m e n t a l and p o r p h y r o b l a s t i c a p p e a r a n c e due t o metamorphism. A g r a p h i t i c limestone c o n t a i n i n g u n f o l i a t e d w h i t e q u a r t z s a n d s t o n e a l s o o c c u r s i n the area. A l l t h e s e r o c k s have u n d e r g o n e g r e e n s c h i s t f a c i e s r e g i o n a l metamorphism and l o c a l l y c o n t a i n a b u n d a n t c h l o r i t e . P o s t m e t a m o r p h i c i n t r u s i o n of d i o r i t e and l a m p r o p h y r e d y k e s , c u t t h r o u g h the r o c k s o f t h e p r o p e r t y . Structure: The c o n t a c t between the d i f f e r e n t u n i t s a p p e a r i n s e v e r a l p l a c e s t o be p l a n a r b u t n o t c o n t i n o u s a l o n g s t r i k e . The w e l l d e v e l o p e d f o l i a t i o n , p a r a l l e l t o s u b - p a r a l l e l w i t h the l i t h o l o g i e s , i s g e n t l y warped; t h i s p r o b a b l y i n d i c a t e s the p r e s e n c e of a l a r g e open f o l d p l u n g i n g t o t h e n o r t h a c r o s s t h e property. Steeply dipping north-northeasterly trending f a u l t s t r u n c a t e and o f f s e t some of t h e u n i t s . M i n e r a l i z a t i o n : The p r o p e r t y i s the p r o b a b l e h o s t o f s t r a t i f o r m m a s s i v e s u l p h i d e d e p o s i t s as f o u r z o n e s c o n t a i n m i n e r a l i z a t i o n : 1 ) a s e r i e s o f f i v e l e n s e s (5 t o 20cm t h i c k ) o f m a s s i v e s u l p h i d e c o n t a i n i n g m a i n l y p y r r h o t i t e and s m a l l amounts o f s p h a l e r i t e and c h a l c o p y r i t e a s s o c i a t e d w i t h abundant s i l i c a (the m i n e r a l i z e d l e n s e s a r e c o n f o r m a b l e t o t h e f o l i a t i o n ) , 2) a s e r i e s o f narrow l a y e r s (1 t o 3cm t h i c k ) o f m a s s i v e p y r i t e w i t h i n a c h l o r i t i c q u a r t z p h y l l i t e u n i t , 3) p y r i t e r i c h m e t a - r h y o l i t e t h a t may be a m e t a m o r p h i c e q u i v a l e n t of a q u a r t z - p y r i t e e x h a l a t i v e u n i t , and 4) a n a r r o w (1 t o 3cm t h i c k ) s i l v e r r i c h , g a l e n a - c h a l c o p y r i t e q u a r t z - c a l c i t e v e i n c u t t i n g through s e r i c i t i c c h l o r i t e quartz s c h i s t . An a l t e r a t i o n zone c o n s i s t i n g o f s e c o n d a r y q u a r t z , m u s c o v i t e , b i o t i t e and a c t i n o l i t e i s p r e s e n t i n the l o w e r p a r t of the s e c t i o n . T h i s zone has c h a r a c t e r i s t i c s s i m i l a r t o a t h e r m a l m e t a m o r p h i c a u r e o l e and i s i n t e r p r e t e d by R o b i n s o n (1986) t o have been g e n e r a t e d by a i n t r u s i v e a t d e p t h . Sample D e s c r i p t i o n : Samples c o l l e c t e d c o n s i s t o f f i n e g r a i n e d m a s s i v e s u l p h i d e s c o n t a i n i n g g a l e n a a s s o c i a t e d w i t h abundant p y r r h o t i t e and m i n o r s p h a l e r i t e . R e f e r e n c e ROBINSON, C. 1986. G e o l o g y of t h e F o r d p r o p e r t y Adams P l a t e a u , south c e n t r a l B r i t i s h Columbia. Unpublished BSc T h e s i s , U n i v e r s i t y of B r i t i s h C o l u m b i a .  11 5  SILVER KING-A: M i n f i l e number: 082M-129 M i n e r a l I n v e n t o r y number: 82M4-AG3 Map number: 036; L a t . 50.950N Long.  119.480W  L o c a t i o n : T h i s s m a l l s h o w i n g i s l e s s t h a n 500m n o r t h o f t h e Spar d e p o s i t a l o n g t h e l o g g i n g r o a d l e a d i n g t o t h e L u c k y Coon deposit. D e s c r i p t i o n : M i n e r a l i z a t i o n occurs i n a l t e r e d limestone i n close p r o x i m i t y t o b r e c c i a t e d rock c o n t a i n i n g fragments of a r g i l l i t e ( f r e s h and p a r t i a l l y r e p l a c e d ) cemented by s u g a r y q u a r t z . The s u l p h i d e s do n o t o c c u r d i r e c t l y i n t h e b r e c c i a and seem r e s t r i c t e d t o t h e s u r r o u n d i n g l i m e s t o n e . Zones r i c h i n c a l c i t e , f l u o r i t e and p o r c e l a n e o u s q u a r t z o c c u r a d j a c e n t t o t h e sulphides. Sample d e s c r i p t i o n : S m a l l seams o f f i n e g r a i n e d g a l e n a mixed w i t h c o a r s e r s p h a l e r i t e g r a i n s i n a c a l c i t i c gangue a r e c h a r a c t e r i s t i c o f t h e sampled s p e c i m e n s . Reference:  BCDM GEM  1971, p . 436.  SILVER KING-SILVER QUEEN: A l s o known a s : K i n g James M i n f i l e number: 082L-NW044 Map number: 045; L a t . 50.950N  Long.  119.480w  L o c a t i o n : A l a r g e e x p o s u r e o f t h i s v e i n o c c u r s on t h e e a s t s i d e o f S c o t c h C r e e k 8km n o r t h o f t h e p o s t o f f i c e o f S c o t c h C r e e k a l o n g t h e l o g g i n g r o a d t h a t f o l l o w s t h e power l i n e . D e s c r i p t i o n : M i n e r a l i z a t i o n o c c u r s i n a v e i n system which i s a b o u t 30m w i d e and s t r i k e s n o r t h w e s t e r l y t h r o u g h t h e c h l o r i t i c s c h i s t and c a l c a r e o u s p h y l l i t e o f u n i t EBG. The v e i n c o n t a i n s p o c k e t s o f c o a r s e g r a i n e d g a l e n a and s p h a l e r i t e i n q u a r t z - c a l c i t e gangue. References:  BCDM GEM 1977, p . E 8 5 . BCDM GEM 1975, p . E 5 5 .  11 6  PET: M i n f i l e number: 082M-143 Map number: 026; L a t . 51.050N  L o n g . 119.530W  L o c a t i o n : T h i s showing i s e x p o s e d i n a t r e n c h , a b o u t of t h e main w o r k i n g s of t h e S p a r d e p o s i t . D e s c r i p t i o n : S m a l l amounts of g a l e n a o c c u r s as d i s s e m i n a t i o n i n c h l o r i t i c  and s p h a l e r i t e schist.  Sample d e s c r i p t i o n : No d e s c r i p t i o n i s a v a i l a b l e . from a n a l y s e s by t h e GSC (GSC number: G79PE). Refernces:  BCDM ASS BCDM GEM  1km  south  (marmate)  Data used  came  RPT 5919. 1976, p. E59.  RED MINERAL CLAIMS: A l s o known a s : Fox, Deer, F i r , P a t , Joe M i n f i l e number:82M-154 Map numbers: 033 L a t . 51.080N Long. 034 51.100N 035 51.070N 037 51.050N  119.380W 119.380W 119.380w 119.540w  L o c a t i o n : The m i n e r a l i z e d s h o w i n g s a r e c l u s t e r e d a r o u n d L i c h e n M o u n t a i n , l o c a t e d n o r t h w e s t of t h e M o s q u i t o K i n g d e p o s i t , a b o u t 3km e a s t - s o u t h e a s t of t h e j u n c t i o n of C r o s s and K w i k o i t C r e e k s . H o s t Rock: The m i n e r a l i z a t i o n i s m o s t l y f o u n d i n c a r b o n a t e l a y e r s a s s o c i a t e d w i t h a r g i l l i t e s and m e t a - v o l c a n i c s (EBG). L o c a l l y manganese r i c h bands o c c u r n e a r t h e m i n e r a l i z e d z o n e s . The r o c k s a r e f o l d e d and metamorphosed, as a r e t h e i r e q u i v a l e n t s e l s e w h e r e on t h e Adams P l a t e a u . The main f o l i a t i o n i n t h e r o c k s s t r i k e s n o r t h e a s t and d i p s n o r t h . Mineralization: These m i n e r a l o c c u r r e n c e s are of s m a l l s i z e , o u t c r o p on s u r f a c e , and do n o t have any known u n d e r g r o u n d e x t e n t . Quartz v e i n s c o n t a i n i n g a r g e n t i f e r o u s galena cut through b o t h v o l c a n i c r o c k s and l i m e s t o n e . The m i n e r a l i z a t i o n has been d e s c r i b e d as c o n f o r m a b l e l e n s e s o f c y l i n d r i c a l shape; but t h i s g e o m e t r y c o u l d n o t be c o n f i r m e d i n t h e f i e l d . Sample d e s c r i p t i o n : A l l t h e c o l l e c t e d samples c o n t a i n c o a r s e g a l e n a i n q u a r t z gangue a s s o c i a t e d w i t h v a r i a b l e amounts of s p h a l e r i t e and p y r i t e . The g a l e n a from t h e o c c u r r e n c e number 033, above, c l e a r l y shows e v i d e n c e of d e f o r m a t i o n . References:  BCDM Open F i l e . BCDM E x p l o r a t i o n i n BC  1979  11 7  JOHNSON LAKE AREA:  AGATE BAY: A l s o known a s : T r y Me, R a n k i n Group, K a r e n , J o e M i n f i l e number: 082M-053 Map number: 006; L a t . 51.08ON L o n g . 119.75oW L o c a t i o n : The showing i s e x p o s e d a t t h e s h o r e n o r t h e r n end o f Squaam Bay.  line  near the  H o s t Rock: F i n e - g r a i n e d q u a r t z - s e r i c i t e s c h i s t s a r e i n t e r b e d d e d w i t h c h l o r i t i c s c h i s t (EBAa). These g r e e n s t o n e s a r e h i g h l y a l t e r e d and c o n t a i n s w e l l s o f c a r b o n a t e s ( c a l c i t e and a n k e r i t e ) . T h i s u n i t , mapped as p a r t o f t h e f e l s i c p a c k a g e o f t h e E a g l e Bay F o r m a t i o n , b e a r more r e s e m b l a n c e t o t h e more m a f i c s e q u e n c e ( u n i t EBG) f o u n d t o t h e n o r t h , and on t h e o t h e r s i d e o f Adams Lake. S t r u c t u r e : The m i n e r a l i z a t i o n o c c u r s w i t h i n a h i g h l y a l t e r e d s c h i s t package. The main f o l i a t i o n s t r i k e s i n a v e r a g e a t N70oW and d i p s from 22o t o 55o n o r t h e a s t . Abundant s m a l l f a u l t s c u t the s c h i s t . M i n e r a l i z a t i o n : Low g r a d e Pb-Zn-Cu o c c u r s i n q u a r t z v e i n s . Two t y p e s o f v e i n s c u t t h e h o s t r o c k s : 1 ) narrow (1 t o 3cm t h i c k ) c l o s e l y s p a c e d v e i n s more o r l e s s c o n f o r m a b l e t o t h e s c h i s t o s i t y , 2) d i s c o n t i n o u s l a r g e r v e i n s (8 t o 40cm t h i c k ) s c a t t e r e d t h r o u g h t h e s c h i s t s , as pods o r l e n s e s . A l l the v e i n - l i k e masses p i n c h and s w e l l e r r a t i c a l l y and a r e t r u n c a t e d by f a u l t s . In both types of o c c u r r e n c e s , the s u l p h i d e s a r e e r r a t i c a l y d i s t r i b u t e d and c o n s i s t o f p y r i t e and s p h a l e r i t e w i t h t r a c e s o f g a l e n a and c h a l c o p y r i t e i n a q u a r t z , c a l c i t e and a n k e r i t e gangue. T o u r m a l i n e has been r e p o r t e d i n t h e s e v e i n s (BCDM, 1961). Sample d e s c r i p t i o n : E u h e d r a l g a l e n a veins c u t t i n g a l t e r e d greenstone. References:  grains  BCDM ASS RPT 4135. BCDM MMAR 1961 pp. 53-55.  inquartz-calcite  11 8  TWIN MOUNTAIN: A l s o known a s : S t a r , Max, Hope M i n f i l e number: 082M-020 M i n e r a l I n v e n t o r y number: 82M4-PB3 Map number: 019; L a t . 51.13ON Long. Grade: S u b j e c t i v e r e p r e s e n t a t i v e of  119.80OW  a v e r a g e v a l u e o f 11 s a m p l e s c o n s i d e r e d t o be t h e m i n e r a l i z e d zone (BCDM ASS RPT 9882) a r e : 0.170 8.84 0.90 2.15 0.18  g / t Au g / t Ag % Pb % Zn % Cu  B a r i t e i s also present in q u a n t i t i e s s u f f i c i e n t p o s s i b l e economic i n t e r e s t .  L o c a t i o n : The showing o c c u r s on t h e s o u t h - e a s t Samatosum M o u n t a i n a t an e l e v a t i o n of 1,200 to workings are a c c e s s i b l e v i a logging roads.  to  be  of  f l a n k of 1,500m. The  old  H o s t R o c k : Two c o n f o r m a b l e m i n e r a l i z e d z o n e s o r v e i n s a r e h o s t e d by g r e e n s c h i s t and c h l o r i t e s c h i s t d e r i v e d from m a f i c t o i n t e r m e d i a t e v o l c a n i c and v o l c a n i c l a s i c r o c k s (EBGq). These r o c k s c o n t a i n a b u n d a n t t h i n c a r b o n a c e o u s l a y e r s and f r a c t u r e f i l l i n g s , and show remnant p i l l o w s t r u c t u r e s . Tuffaceous and more s i l i c e o u s h o r i z o n s o c c u r w i t h i n t h e g r e e n s c h i s t . This p a c k a g e of r o c k s i s o v e r l a i n by t h e T s h i n a k i n L i m e s t o n e . S t r u c t u r e : R o c k s i n the a r e a a r e m o d e r a t e l y c o n t o r t e d and places e x h i b i t kink banding. The main f o l i a t i o n s t r i k e s N40OW and d i p s 4 3 0 N W .  in  M i n e r a l i z a t i o n : The v e i n s o r m i n e r a l i z e d z o n e s c o n t a i n p y r i t e , c h a l c o p y r i t e , s p h a l e r i t e and g a l e n a i n a c a r b o n a t e gangue w i t h minor q u a r t z , and b a r i t e ; t h e z o n e s l o c a l l y a r e a z u r i t e s t a i n e d . M i n e r a l i z e d zones r a n g e i n w i d t h from 20cm t o o v e r 1m. An apparently unrelated vein lacking v i s i b l e mineralization c o n t a i n s up t o an e s t i m a t e d 30 p e r c e n t b a r i t e . Sample d e s c r i p t i o n : The a n a l y s e d s a m p l e s a r e from an open t r e n c h c l o s e to the o l d a d i t s . They c o n t a i n b l o b s o f s p h a l e r i t e , p y r i t e and g a l e n a i n a c a l c i t i c matrix. R e f e r e n c e s : BCDM ASS RPT 9882, BCDM MMAR 1936, p.  2093. D39.  11  Art: M i n f i l e number: 082M-124 Map number: 0 1 7 ; Lat. 5 1 . 1 0 O N  Location: C r e e k and  Long.  9  119.95ow  T h i s showing i s a d j a c e n t t o t h e r o a d between L o u i s Squaam Bay, n e a r t h e e a s t end o f F o r e s t L a k e .  H o s t Rock: M i n e r a l i z a t i o n i s h o s t e d by a s p o t t e d q u a r t z muscovite s c h i s t c o n t a i n i n g limy q u a r t z i t i c pods. This schist i s p a r t o f t h e s u b u n i t EBSs c h a r a c t e r i z e d by p h y l l i t i c s a n d s t o n e , g r i t , p h y l l i t e , c h l o r i t e s c h i s t , and q u a r t z i t e w i t h a s m a l l amount of l i m e s t o n e . M i n e r a l i z a t i o n : Quartz carbonate v e i n s c o n t a i n i n g minor and g a l e n a c u t t h e s c h i s t . T r a c e s of f u c h s i t e are a l s o Sample d e s c r i p t i o n : Q u a r t z v e i n s i n t h e s c h i s t g a l e n a a s s o c i a t e d w i t h minor c a r b o n a t e s . References:  BCDM M i n f i l e  number  082M-124.  pyrite present.  c o n t a i n pods of  120  HOMESTAKE: M i n f i l e number: 082M-025 M i n e r a l i n v e n t o r y number: 82M4-AG1 Map number: 011; L a t . 51.11 O N L o n g . 119.83ow Reserve:  p r o v e n (The F i n a n c i a l P o s t , J a n . 1,010,800.0 t o n n e s of o r e : 240.0 2.5 4.0 0.6 28.0  Production,  as  listed  g/t % % % %  1973)  are  Ag Pb Zn Cu barite  in Minfile:  6,965 t o n n e s of o r e (between 1935 t o 1941)  12,400 9,565,900 11,080 171,325 426,520  g g kg kg kg  Au Ag Cu Pb Zn  L o c a t i o n : A c c e s s t o t h e p r o p e r t y i s by a s w i t c h b a c k l e a v e s t h e main r o a d 5km n o r t h w e s t of Squaam Bay.  road  that  H o s t Rock: The m i n e r a l i z e d b a r i t e l e n s e s a r e o v e r l a i n by s i d e r i t i c p h y l l i t e t h a t c o n t a i n i n t e r b e d d e d a r g i l l i t e , and by a t u f f a c e o u s c h l o r i t i c s c h i s t u n i t (EBAa). A wide zone of a l t e r e d r o c k o c c u r s below the m i n e r a l i z e d l e n s . R e g i o n a l metamorphism and l o c a l h y d r o t h e r m a l a l t e r a t i o n have o b s c u r e d t h e p r i m a r y c o m p o s i t i o n of t h e h o s t r o c k s ; c o n s e q u e n t l y , t h e f o l l o w i n g u n i t d e s c r i p t i o n s a r e b a s e d on m i n e r a l a s s e m b l a g e s ( T a b l e ). A p o o r l y e x p o s e d c h l o r i t e p h y l l i t e ( u n i t 1) o c c u r s i n t h e s o u t h e r n p a r t o f t h e map a r e a ( F i g . A . 1 ) . It is a thinly laminated brownish green c h l o r i t e p h y l l i t e t h a t i s n o t i c e a b l y l e s s f o l i a t e d than the o v e r l y i n g s c h i s t s . U n i t 2 c o m p r i s e s d o m i n a n t l y s e r i c i t e - q u a r t z s c h i s t w i t h abundant disseminated p y r i t e throughout. U n i t 2a i s a more m a s s i v e p h a s e o f t h e " p a p e r " s c h i s t of u n i t 2b and c o n t a i n s l e n t i c u l a r , s i l i c a - r i c h s e g r e g a t i o n s up t o 6 cm i n l e n g t h . U n i t 2b, r e f e r r e d t o as a s e r i c i t e - q u a r t z " p a p e r " s c h i s t , i s t h e most c o n s p i c u o u s u n i t i n t h e map a r e a . In o u t c r o p , the paper s c h i s t u n i t i s e a s i l y d i s c e r n i b l e by i t s f i s s i l e a p p e a r a n c e and by i t s w e a t h e r e d c o a t i n g of y e l l o w f e r r i c s u l p h a t e . I t i s t h e h o s t and t h e f o o t w a l l t o t h e b a r i t e - s u l p h i d e l e n s e s and i s i n t e r p r e t e d t o be a h i g h l y a l t e r e d , p r e d o m i n a n t l y f e l s i c t u f f u n i t . A number of q u a r t z v e i n s up t o a m e t r e t h i c k a r e f o u n d w i t h i n the p a p e r s c h i s t below t h e b a r i t e  OJ n j O H-  0 ua CD C W  H  01 H O OJ  CD > • ->  0. N  'IT  UNIT 5 .  a  cn 3:  OJ r-h M O O Ml  3  zt  rr  •'C|;UNIT 4  O fD » OJ  3  o 3  D-. CD  tn  1  O rt O OJ C X  . UNIT  1  \ \  v  UNIT 3 \  2b  n- ro  (D TJ M  -  M  O  •o  -» CD  *X> M  00 r t cn •  in  M"  o H-  ua ua CD  o 1-' o  ua •<:  OJ  a  LEGEND EAGLE BAY FORMATION I 5 I  TUFFACEOUS CHLORITIC SCHIST  I 4 I  ANKERITIC PHYLLITE. 4a — ARGILLITE  [~3~|  CHLORITE SCHIST  I 2c j  MINERALIZATION: BARITE BLUFF  I 2b I  SERICITE-QUARTZ PAPER SCHIST  I 2o I  SERICITE-QUARTZ SCHIST  I I I  CHLORITE PHYLLITE  UNIT I UNIT  2o  122  l e n s e s ; they sulphides.  contain pyrite  but are g e n e r a l l y barren of other  A d a r k g r e e n l a m i n a t e d c h l o r i t e s c h i s t ( u n i t 3) o c c u r s s t r a t i g r a p h i c a l l y above and l a t e r a l l y west o f u n i t 2b. I t c o n s i s t s of carbonate phenocrysts w i t h i n a f i n e - g r a i n e d c h l o r i t e - f e l d s p a r matrix. T h e s e p h e n o c r y s t s , w h i c h may be p s e u d o m o r p h i c a f t e r p l a g i o c l a s e , a r e rimmed and p a r t i a l l y r e p l a c e d by c h l o r i t e . This unit i s probably a l t e r e d andesite t u f f ; i t s c o n t a c t w i t h u n i t 2b i s i n p a r t an i n t e r f i n g e r i n g o f f e l s i c and i n t e r m e d i a t e t u f f s b u t may a l s o r e f l e c t an i r r e g u l a r p e r v a s i v e p o t a s s i c and s i l i c i c a l t e r a t i o n b o u n d a r y . A f i n e - g r a i n e d a n k e r i t i c p h y l l i t e ( u n i t 4) composed o f interbedded l a y e r s of a n k e r i t e - b e a r i n g c h l o r i t i c p h y l l i t e occurs a b o v e u n i t s 2b and 3. I n o u t c r o p l i m o n i t i c pseudomorphs a f t e r i r o n - r i c h c a r b o n a t e g i v e t h e r o c k s a c h a r a c t e r i s t i c brown t i n g e . Some f i n e - g r a i n e d p y r i t i c a r g i l l i t e s w i t h i n t h e p h y l l i t e p a c k a g e a r e t h e most c o n t i n u o u s and r e l i a b l e marker u n i t s a t Homestake. These a r g i l l i t e l a y e r s c o n t a i n e l o n g a t e d q u a r t z e y e s and a u g e n - s h a p e d c l a s t s up t o 0.8 mm i n d i a m e t e r . The q u a r t z e y e s have c o r e s o f e u h e d r a l p y r i t e c r y s t a l s and a r e s e t i n a f i n e - g r a i n e d p y r i t i c carbonaceous matrix of p h y l l o s i l i c a t e s , q u a r t z , and f e l d s p a r . U n i t 4 i s i n t e r p r e t e d t o be l a r g e l y a sedimentary c l a s t i c rock with interbedded c h l o r i t i c t u f f l a y e r s . A t u f f a c e o u s c h l o r i t e s c h i s t ( u n i t 5) o c c u r s on t h e s t e e p c l i f f s i n t h e u p p e r , n o r t h e r n p o r t i o n o f t h e Homestake a r e a . The r o c k c o n t a i n s m a s s i v e and t u f f a c e o u s zones composed o f c h l o r i t e and c a r b o n a t e ( p r o b a b l y d e v e l o p e d from r e g i o n a l metamorphism o f r o c k s o f i n t e r m e d i a t e c o m p o s i t o n such as a n d e s i t e ) . Relict f l a t t e n e d f e l s i c c l a s t s imply a p y r o c l a s t i c o r i g i n f o r a t l e a s t p a r t of t h i s u n i t . P y r i t i c q u a r t z v e i n s and c a l c i t e s t r i n g e r s o c c u r t h r o u g h o u t t h e s c h i s t , and i n s e v e r a l p l a c e s c u t t h e foliation. L o c a l l y , c h e r t y pods and a r g i l l i t e l a y e r s a r e interbedded with the s c h i s t . T h i s u n i t i s o v e r l a i n by a t h i c k g r e e n s t o n e s e q u e n c e (V.A. P r e t o , p e r s . comm., 1 9 8 5 ) . Structure: A well defined penetrative mineral f o l i a t i o n i s u b i q u i t o u s t h r o u g h o u t t h e Homestake a r e a . The f o l i a t i o n i s o u t l i n e d by t h e p r e f e r r e d o r i e n t a t i o n o f p l a t y m i n e r a l s s u c h as s e r i c i t e and c h l o r i t e , and l e n t i c u l a r s i l i c a - r i c h s e g r e g a t i o n s i n u n i t 2. F o l i a t i o n p l o t t e d on a s t e r e o n e t ( F i g . A . 2 ) , h a s a r e a s o n a b l y t i g h t c l u s t e r a r o u n d a maximum t h a t s t r i k e s 120 d e g r e e s and d i p s 30 d e g r e e s n o r t h e a s t . O r i g i n a l compositional layering generally i s d i f f i c u l t to see. E x c e p t w i t h i n t h e a r g i l l i t e bands o f u n i t 4, i t has been l a r g e l y o b s c u r e d by e i t h e r metamorphism o r t h e i n t e n s e d e f o r m a t i o n . In g e n e r a l , however, i t s t r i k e s between 120 and 160 d e g r e e s w i t h  123  N  F i g u r e A.2. Lower h e m i s p h e r e e q u a l a r e a p r o j e c t i o n s o f s t r u c t u r a l e l e m e n t s Homestake d e p o s i t a r e a : A- P o l e s (92) t o f o l i a t i o n , maximun c o n c e n t r a t i o n - 3 0 % B- P o l e s (15) t o c o m p o s i t i o n a l l a y e r i n g , maximum c o n c e n t r a t i o n -33%. C o n t o u r i n t e r v a l s - 1 , 10 (from Hoy and G o u t i e r , 1986).  124  an a v e r a g e d i p of 35 d e g r e e s n o r t h e a s t ( F i g . A . 2 ) . The s i m i l a r i t y between f o l i a t i o n and b e d d i n g a t t i t u d e s i n d i c a t e s e i t h e r t i g h t o r i s o c l i n a l f o l d i n g or a c o n s t a n t f a c i n g d i r e c t i o n . No l a r g e f o l d s have been i d e n t i f i e d i n t h e c h l o r i t e o r s e r i c i t e p h y l l i t e s beneath the b a r i t e l e n s e s . Nearly a l l b e d d i n g - c l e a v a g e i n t e r s e c t i o n s i n t h e s e p h y l l i t e s have a common vergence. T h e r e f o r e , t h e s u c c e s s i o n c o u l d be a h o m o c l i n a l , n o n - f o l d e d s e q u e n c e on t h e l o w e r , u p r i g h t l i m b o f a t i g h t syncline. However, r o o t l e s s t i g h t t o i s o c l i n a l minor f o l d s t h r o u g h o u t t h e s u c c e s s i o n and t h e p r e s e n c e o f l a r g e f o l d s o u t l i n e d by a r g i l l i t e beds i n o v e r l y i n g r o c k s ( u n i t 4) s u g g e s t t h a t l a r g e r f o l d s a l s o o c c u r w i t h i n t h e p h y l l i t e s . These f o l d s would be a s y m m e t r i c , e s s e n t i a l l y c o n f i n e d t o a s i n g l e u n i t , w i t h s h o r t e n e d or s h e a r e d - o u t o v e r t u r n e d f o l d s l i m b s . On a r e g i o n a l s c a l e the Homestake p r o p e r t y i s l o c a t e d on t h e s o u t h e r n l i m b of a l a r g e o v e r t u r n e d s y n c l i n e ( S c h i a r i z z a and P r e t o 1984; Preto and S c h i a r i z z a , 1 9 8 5 ) . E v i d e n c e i n t h e Homestake a r e a , i n c l u d i n g f o l d c l o s u r e s and v e r g e n c e s o b t a i n e d from bedding-cleavage i n t e r s e c t i o n s , supports a s y n c l i n a l f o l d c l o s u r e to the n o r t h e a s t . M i n e r a l i z a t i o n : A number of b a r i t e s u l p h i d e l e n s e s w i t h v a r i a b l e amounts of s u l p h i d e o c c u r w i t h i n t h e u p p e r p a r t of u n i t 2b. They a r e d e s c r i b e d i n d e t a i l i n e a r l y M i n i s t r y o f M i n e s A n n u a l R e p o r t s (1927, 1936) and a r e b r i e f l y r e v i e w e d h e r e . At l e a s t t h r e e l e n s e s , s e p a r a t e d by s e r i c i t e s c h i s t , a r e r e c o g n i z e d . They r a n g e i n t h i c k n e s s f r o m l e s s t h a n a m e t r e t o a t l e a s t 10 m e t r e s ; u n d e r g r o u n d some have been t r a c e d s e v e r a l h u n d r e d metres. M e t a l l i c minerals within these lenses include t e t r a h e d r i t e , galena, s p h a l e r i t e , p y r i t e , chalcopyrite, a r g e n t i t e , m i n o r n a t i v e s i l v e r , and t r a c e r u b y s i l v e r and native gold. The l e n s e s may c o n s i s t e i t h e r o f m a s s i v e t o banded b a r i t e w i t h o n l y s c a t t e r e d m e t a l l i c m i n e r a l s t h r o u g h o u t , or i n t e r l a y e r e d b a r i t e , s c h i s t , and s u l p h i d e s . Two l e n s e s a r e e x p o s e d on surface. The l a r g e s t , r e f e r r e d t o as the " b a r i t e b l u f f " ( u n i t 2 c ) , has an e x p o s e d t h i c k n e s s of 5 t o 6 m e t r e s . I t p i n c h e s out r a p i d l y a l o n g s t r i k e , has a s h a r p h a n g i n g w a l l c o n t a c t w i t h s e r i c i t e s c h i s t , and g r a d e s downward i n t o m a s s i v e s e r i c i t i c chert. A s m a l l e r l e n s , 1 t o 2 m e t r e s t h i c k , o c c u r s below t h e " b a r i t e b l u f f " u n i t ; i t i s banded but c o n t a i n s o n l y minor sulphides. Sample d e s c r i p t i o n : Samples were c o l l e c t e d from the b a r i t e b l u f f and a r e composed of e r r a t i c a l l y d i s t r i b u t e d medium g r a i n e d p y r i t e , s p a l e r i t e and g a l e n a . G a l e n a sample from q u a r t z v e i n m a t e r i a l was a l s o a n a l y s e d . R e f e r e n c e s : HOY,T.,and GOUTIER,F.  1986.  125  REA GOLD: A l s o known a s : H i l t o n M i n f i l e number: 082M-091 Map number: 015; L a t . 51.13ON Published  drill  Long.  indicated reserves:  119.81ow  120,000 t o n n e s o f o r e . 18.2 g t Au 141.2 g t Ag 0.85 % Cu 4.11 % Zn 3.67 % Pb  L o c a t i o n : The Rea G o l d p r o p e r t y i s l o c a t e d west o f Samatosum m o u n t a i n and i s a c c e s s i b l e v i a l o g g i n g r o a d f r o m Squaam Bay. H o s t R o c k : The d e p o s i t d e s c r i p t i o n i s from Hoy and G o u t i e r (1986). The d e p o s i t i n c l u d e s two t h i n , l a t e r a l l y c o n t i n u o u s l e n s e s t h a t l i e s t r a t i g r a f i c a l l y above a h i g h l y a l t e r e d s e q u e n c e o f d o m i n a n t l y m a f i c and m i n o r f e l s i c t u f f s ( F i g . A . 3 ) . S t r a t i g r a p h i c a l l y above t h e s e l e n s e s i s a t h i n m a f i c t u f f s e q u e n c e and a t h i c k e r s e q u e n c e o f a r g i l l i t e , s i l t s t o n e , and g r i t s (EBFf). The s u c c e s s i o n i s i n v e r t e d ; h e n c e , t h e " f o o t w a l l a l t e r a t i o n z o n e " o r " s t o c k w o r k f e e d e r z o n e " now forms t h e hangingwall of the l e n s e s . Rock U n i t s : The o l d e s t u n i t w i t h i n t h e d e p o s i t a r e a c o m p r i s e s p r e d o m i n a n t l y m a f i c t u f f ( u n i t 1) t h a t l i e s a t t h e s t r u c t u r a l top of the s u c c e s s i o n . This tuff unit includes ash, c r y s t a l , and l a p i l l i t u f f s w i t h v a r i a b l e amounts o f d i s s e m i n a t e d pyrite. They a r e s t o n g l y f o l i a t e d , p r o d u c i n g g r e e n p h y l l i t e s and s c h i s t s ; more m a s s i v e " g r e e n s t o n e " u n i t s may be d e r i v e d from mafic flows. T h e r e a r e t h i n c h e r t bands and a n o t i c e a b l e i n c r e a s e i n s e r i c i t e c o n t e n t t o w a r d t h e c o n t a c t w i t h u n i t 2. I n g e n e r a l , t h i s c o n t a c t i s g r a d a t i o n a l and r e f l e c t s , i n p a r t , an i n c r e a s e i n a l t e r a t i o n i n the s t r a t i g r a p h i c f o o t w a l l of the deposit. U n i t 2 i s t h e f o o t w a l l a l t e r a t i o n o r s t o c k w o r k f e e d e r zone o f the s u l p h i d e l e n s e s . I t i s v e r y e x t e n s i v e i n t h e h a n g i n g w a l l of t h e more n o r t h e r l y o f t h e two l e n s e s , b u t i s o n l y a few m e t r e s t h i c k i n t h e h a n g i n g w a l l o f RG8, t h e s o u t h e r n l e n s . I t includes e x t e n s i v e l y a l t e r e d mafic t u f f s , otherwise s i m i l a r t o those of u n i t 1, c h e r t l a y e r s , and t h i n more f e l s i c ( d a c i t e ?) a s h t u f f layers. T h e s e u n i t s now a p p e a r a s p a l e t a n t o p a l e g r e e n s i l i c e o u s p h y l l i t e s and s c h i s t s i n t e r b e d d e d w i t h p u r e t o s e r i c i t i c chert. A l t e r a t i o n i n c r e a s e s d r a m a t i c a l l y toward the contact with the sulphide lenses. I t i n c l u d e s : a) s i l i c i f i c a t i o n t h r o u g h i n t r o d u c t i o n o f s i l i c a i n t h e form o f q u a r t z v e i n s , and o f t h i n t o r e l a t i v e l y t h i c k c h e r t l a y e r s , d i s c o n t i n u o u s c h e r t l a m e l l a e , and f r a g m e n t a l chert;  126  o  T"  8  o  s  T" o  I580-  LEGEND UNIT 6 ARGILLITE: MINOR WACKE. GRIT WACKE. GRIT: MINOR ARGILLITE UNIT 5 | 6 | MAFIC TUFF: MINOR ARGILLITE f"c~| DARK GREY TUFFACEOUS ARGILLITE UNIT 4 BARITE: MINOR SULPHIOES UNIT 3 MASSIVE' SULPHIDES UNIT 2 |  | MAFIC TUFF. SILICIFIED. CHERT MINOR DACITE (?) TUFF  UNIT 1 |  Figure barite  | MAFIC TUFF: MINOR SILICIFICATION  A.3 V e r t i c a l s e c t i o n ( 9 7 + 0 0 ) t h r o u g h t h e RG 8 l e n s , R e a G o l d d e p o s i t ( f r o m Hoy a n d G o u t i e r ,  sulphide 1986).  127  b) p y r i t e , w h i c h i s d i s s e m i n a t e d , i n v e i n s , and i n d i s c o n t i n u o u s s t r e a k s ; i t i n c r e a s e s from 1 t o 2 p e r c e n t i n u n i t 1 t o commonly 10 t o 20 p e r c e n t n e a r t h e s t r a t i g r a p h i c t o p o f u n i t 2; and c ) s e r i c i t e w h i c h becomes u b i q u i t o u s w i t h i n u n i t 2. W h i t e (1985) n o t e d b o t h l o c a l soda e n r i c h m e n t ( a s m a s s i v e a l b i t e and p a r a g o n i t e ) and c a r b o n i z a t i o n ( a s d o l o m i t e , i r o n - r i c h m a g n e s i t e , and c a l c i t e ) . S t r a t i g r a p h i c a l l y o v e r l y i n g the sulphide or s u l p h i d e - b a r i t e l e n s e s i s a t h i n s e q u e n c e o f p r e d o m i n a n t l y m a f i c t u f f s ( u n i t 5) t h a t g r a d e s up i n t o a r g i l l i t e s . These t u f f s a r e p a l e grey t o brown-weathering thin-bedded c h l o r i t e p h y l l i t e s . Silicified zones o c c u r o n l y l o c a l l y and p y r i t e c o n t e n t i s g e n e r a l l y low. A d a r k g r e y t u f f a c e o u s " a r g i l l i t e " ( u n i t 5c) w i t h h i g h Ba c o n t e n t ( I . P i r i e , p e r s . comm., 1985) o c c u r s i n t h e i n t e r m e d i a t e f o o t w a l l of t h e RG8 l e n s , a t t h e s t r a t i g r a p h i c base o f u n i t 5. U n i t 5 i s g e n e r a l l y i n f a u l t c o n t a c t w i t h u n i t 6, b u t i n some d r i l l i n t e r s e c t i o n s i t g r a d e s t h r o u g h an i n t e r v a l o f i n t e r b e d d e d g r e e n p h y l l i t e and a r g i l l i t e ( F i g . ). A s e q u e n c e of m e t a c l a s t i c r o c k s ( u n i t 6) a t t h e s t r u c t u r a l base of t h e s u c c e s s i o n a r e the yougest r o c k s i n t h e d e p o s i t a r e a . They c o m p r i s e s g r e y l a m i n a t e d a r g i l l i t e , s i l t s t o n e , wacke, and l o c a l p e b b l e c o m g l o m e r a t e w i t h b o t h v o l c a n i c and s e d i m e n t a r y clasts. B e d d i n g and g r a d e d beds a r e w e l l p r e s e r v e d . Thin mafic a s h t u f f l a y e r s o c c u r i n t h e b a s a l p a r t o f u n i t 6.  S t u c t u r e : The d e p o s i t and h o s t r o c k s a r e w i t h i n a northwest-trending, northeast-dipping homoclinal succession that has been s t r u c t u r a l l y i n v e r t e d . A p r o n o u n c e d m i n e r a l s c h i s t o s i t y l a r g e l y masks p r i m a r y b e d d i n g e x c e p t i n s t r u c t u r a l f o o t w a l l r o c k s where w e l l - b e d d e d and commomly g r a d e d m e t a c l a s t i c rocks occur. The o b s e r v e d b e d d i n g i s s u b - p a r a l l e l t o t h e s c h i s t o s i t y ( F i g . A.4), indicating tight to i s o c l i n a l folding. Changes i n t h e v e r g e n c e o f t h e b e d d i n g - s c h i s t o s i t y i n t e r s e c t i o n s and t h e many s m a l l , r o o o t l e s s i s o c l i n a l f o l d s i n d i c a t e , however, that the s u c c e s s i o n i s f o l d e d . F o l d i n g i s asymmetrical i n s t y l e and i n d i v i d u a l f o l d s a r e c o n f i n e d t o s p e c i f i c u n i t s s i n c e r e p e t i t i o n o f t h e major l i t h o l o g i c s u b d i v i s i o n s i s n o t a p p a r e n t . W i t h i n u n i t 2, c l e a v a g e - b e d d i n g i n t e r s e c t i o n s i n d i c a t e a synformal axis located to the northeast. R e l a t i o n s h i p s between t h e m a s s i v e s u l p h i d e , b a r i t e , and a l t e r a t i o n zone i n d i c a t e t h a t t h e d e p o s i t i s i n v e r t e d ; t h i s s u g g e s t s t h a t t h e o b s e r v e d s c h i s t o s i t y and a s s o c i a t e d f o l d s a r e s e c o n d g e n e r a t i o n s t r u c t u r e s s u p e r i m p o s e d on a p r e v i o u s l y inverted panel. W i t h i n more c o m p e t e n t s t r u c t u r a l f o o t w a l l r o c k s ( u n i t 6 ) , t h e s e f o l d s a r e r e l a t i v e l y open and t h e l o c a t i o n o f f o l d h i n g e s c a n be d e f i n e d . A late southeast-trending c r e n u l a t i o n c l e a v a g e , a s s o c i a t e d w i t h m i n o r open f o l d s , i s s u p e r i m p o s e d on t h e e a r l i e r s c h i s t o s i t y . F a u l t s p a r a l l e l t o s c h i s t o s i t y a r e common b u t o n l y t h e l a r g e s t  N -L  T  F i g u r e A.4 E q u a l a r e a p r o j e c t i o n s o n t o s t r u c t u r a l e l e m e n t s Rea G o l d d e p o s i t : A- P o l e s t o f o l i a t i o n B- P o l e s t o c o m p o s i t i o n a l l a y e r i n g (from Hoy and G o u t i e r , 1986).  lower  hemisphere  129  a r e shown on t h e map. The most p r o m i n e n t f a u l t s t r i k e s n o r t h w e s t , j u x t a p o s i n g u n i t 5 a g a i n s t u n i t 6. The d i s p l a c e m e n t on t h e f a u l t i s p r o b a b l y n o t l a r g e as t h e r e does not a p p e a r t o be much l o s s of s t r a t i g r a p h y a c r o s s i t ; t h e f a u l t c u t s l o c a l l y up i n t o u n i t 5 l e a v i n g a n o r m a l s t r a t i g r a p h i c c o n t a c t between u n i t s 5 and 6. M i n e r a l i z a t i o n : The s u l p h i d e s , w i t h i n t h i s v o l c a n o g e n i c s u l p h i d e - b a r i t e b e a r i n g d e p o s i t , a r e c o n t a i n e d i n two main lenses. The more s o u t h e r n , t h e RG8 l e n s , a p p e a r s t o be a t a s l i g h t l y h i g h e r s t r a t i g r a p h i c l e v e l t h a n t h e L100 l e n s . I t has a l e s s e x t e n s i v e f o o t w a l l a l t e r a t i o n z o n e , and i s " c a p p e d " by massive b a r i t e . D e s c r i p t i o n of t h e s e s u l p h i d e l e n s e s a r e based on v i s u a l e x a m i n a t i o n of d r i l l c o r e and mapping of t r e n c h e s . The RG8 l e n s i s w e l l e x p o s e d i n two t r e n c h e s . I t has a r e l a t i v e l y s h a r p c o n t a c t w i t h a l t e r e d " f o o t w a l l " r o c k s of u n i t 2 and g r a d e s s t r a t i g r a p h i c a l l y up i n t o m a s s i v e b a r i t e of u n i t 4. However i t i s i n s h a r p c o n t a c t w i t h t u f f a c e o u s muds o r m a f i c t u f f s of u n i t 5 a t i t s f r i n g e s . The b a r i t e " c a p " c o n s i s t s of g r e y t o w h i t e , m a s s i v e or f a i n t l y banded b a r i t e w i t h v a r i a b l e amounts of d i s s e m i n a t e d s u l p h i d e s . The s u l p h i d e c o n t e n t of t h e b a r i t e g e n e r a l l y d e c r e a s e s away from t h e u n d e r l y i n g m a s s i v e sulphide (Fig. A.3). The L100 l e n s has a s u r f a c e s t r i k e l e n g t h o f a p p r o x i m a t l y 50 m e t r e s and a down d i p p r o j e c t i o n of a t l e a s t 120 m e t r e s . A t h i c k zone of i n t e n s e s i l i c a a l t e r a t i o n s t r a t i g r a p h i c a l l y below t h e l e n s i s a b r u p t l y o v e r l a i n by m a f i c t u f f s of u n i t 5a. I t does not have a b a r i t e " c a p " . S u l p h i d e mineralogy i n both l e n s e s i n c l u d e s p y r i t e , arsenop y r i t e , s p h a l e r i t e , g a l e n a , c h a l c o p y r i t e , and t e t r a h e d r i t e t e n n a n t i t e (White, 1985). S u l p h i d e s a r e f i n e - g r a i n e d and massive, c r u d e l y laminated or b r e c c i a t e d . Gold o c c u r s mainly i n t h e m a s s i v e s u l p h i d e s but i s a l s o f o u n d i n b a r i t e , i n f o o t w a l l s t o c k w o r k , and i n f a u l t gouge ( I . P i r i e , p e r s . comm., 1 9 8 5 ) . S i l v e r i s a s s o c i a t e d w i t h b o t h b a r i t e and m a s s i v e s u l p h i d e s , w h i l e z i n c , l e a d , and c o p p e r o c c u r p r i m a r i l y i n m a s s i v e sulphides. Sample d e s c r i p t i o n : The sample was c o l l e c t e d from t h e m a s s i v e s u l p h i d e zone o c c u r r i n g on s u r f a c e and i s composed of e x t r e m e l y f i n e - g r a i n e d s u l p h i d e ore c o n t a i n i n g e s s e n t i a l l y p y r i t e , a r s e n o p y r i t e , and s p h a l e r i t e , w i t h o n l y m i n o r g a l e n a . Vein samples c o n t a i n i n g c o a r s e r g a l e n a was a l s o a n a l y s e d . References:  HOY,T.,and GOUTIER,F.  1986.  1 30  BARRIERE LAKES AREA:  BIRK CREEK SHOWINGS: A l s o Known a s : A n a c o n d a , L y n x , Rainbow, Copper C l i f f , M i n f i l e number: 082M-067, (059, 131) M i n e r a l I n v e n t o r y number: 82M5-CU3 Map number: 008; L a t . 51.33ON L o n g . 119.90ow L o c a t i o n : The a r e a i s s i t u a t e d The s h o w i n g s a r e a c c e s s i b l e by s i d e of B i r k C r e e k .  3km west o f N o r t h B a r r i e r e L a k e . t r a i l t h a t f o l l o w s the north-east  H o s t R o c k : The a r e a i s u n d e r l a i n by s e r i c i t e s c h i s t , c h l o r i t e s c h i s t , b l a c k p h y l l i t e , and some r e c r y s t a l l i z e d l i m e s t o n e ( u n i t E B A a ) . Two s t r a t i g r a p h i c s e c t i o n s ; A-A , B-B and a l o n g i t u d i n a l s e c t i o n D-D' c r o s s i n g the s e c t i o n C-C', a r e shown on t h e F i g u r e s , and a r e d e s c r i b e d i n t h e f o l l o w i n g p a r a g r a p h s . Section A-A' A c l i f f s e c t i o n i s e x p o s e d from an e l e v a t i o n o f 970m a t t h e c r e e k t o 1,102m up s e c t i o n . I t c o n s i s t s d o m i n a n t l y of q u a r t z - e y e s e r i c i t e s c h i s t . The s t r i k e of t h e f o l i a t i o n v a r i e s f r o m 265 t o 290 d e g r e e s and d i p s 5 t o 20 d e g r e e s t o t h e n o r t h . The o v e r a l l minimum t h i c k n e s s ( p e r p e n d i c u l a r t o f o l i a t i o n , w h i c h i s a p p r o x i m a t e l y c o i n c i d e n t w i t h b e d d i n g ) i s 175m ( F i g . A.5). At the b a s e of the s e c t i o n the s c h i s t s c o n t a i n 15 p e r c e n t p h e n o c r y s t s (maximum s i z e 2mm) of q u a r t z and p l a g i o c l a s e i n a quartz-muscovite-plagioclase m a t r i x . The p l a g i o c l a s e i s a l t e r e d t o c a l c i t e but up s e c t i o n t h i s a l t e r a t i o n i s n o t a p p a r e n t because the p l a g i o c l a s e c o n t e n t d e c r e a s e s . Autolithic f r a g m e n t a l u n i t s ( a v e r a g e f r a g m e n t s i z e 1.5mm), o c c u r l o c a l l y . D i s s e m i n a t e d p y r i t e w i t h an a v e r a g e g r a i n s i z e o f 0.5mm, c o n s t i t u t e s up t o 8 per c e n t o f t h e r o c k . T r a c e amounts o f interstitial c h a l c o p y r i t e are p r e s e n t w i t h the p y r i t e . No m a r k e d l y s u l p h i d e - r i c h h o r i z o n s were o b s e r v e d . 1  1  Section B-B' T h i s s e c t i o n ( F i g . A.5) p a s s e s c l o s e t o s e v e r a l o l d workings. E x p o s u r e i s l i m i t e d t o one o r two o u t c r o p s and the c o l l a r s o f two slumped a d i t s . A well-developed f o l i a t i o n , p a r a l l e l to c o m p o s i t i o n a l l a y e r i n g , t r e n d s 265 t o 275 d e g r e e s and d i p s g e n t l y n o r t h (3 t o 20 d e g r e e s ) . O b s e r v a b l e b e d r o c k i s composed of q u a r t z - s e r i c i t e and c h l o r i t e s c h i s t w i t h l i m o n i t e a l t e r e d p y r i t e - r i c h l a y e r s , and minor l a m i n a t e d b l a c k p h y l l i t e s . T h i n s e c t i o n s o f t h e s c h i s t s show z o n e s w i t h e l o n g a t e d f r a g m e n t s (up t o 3mm) of p o l y c r y s t a l l i n e q u a r t z g r a i n s . D i s s e m i n a t e d p y r i t e i s p r e s e n t t h r o u g h o u t much of t h e s e c t i o n . S i l i c i f i e d m a s s i v e p y r i t e l e n s e s w i t h m i n o r c h a l c o p y r i t e were o b s e r v e d w i t h i n an 8-metre s e c t i o n n e a r t h e o l d a d i t s . The p y r i t e i s e u h e d r a l , but f r a g m e n t e d , and a s s o c i a t e d w i t h c h a l c o p y r i t e w h i c h g e n e r a l l y i s l o c a t e d a t the b o r d e r s o f t h e p y r i t e g r a i n s . M a t e r i a l o b s e r v e d on a dump i n t h e i m m e d i a t e a r e a c o n t a i n s  1 31  F i g u r e A.5 D e t a i l e d s e c t i o n s A-A and B-B from the n o r t h s i d e of B i r k C r e e k — s e c t i o n s a b o u t 350m a p a r t ( f r o m G o u t i e r e t a l . , 1985). 1  1  1 32  s i m i l a r m i n e r a l i z a t i o n , as w e l l as a few b l o c k s o f v e i n q u a r t z w i t h b l e b s o f s p h a l e r i t e and g a l e n a . The l a t t e r t y p e o f m i n e r a l i z a t i o n was n o t o b s e r v e d i n o u t c r o p . S e c t i o n s C - C and D-D' S e c t i o n s C-C* and D-D' c r o s s a m a j o r showing a l o n g a c l i f f s e c t i o n on t h e s o u t h s i d e o f B i r k C r e e k . Three s h o r t a c c e s s i b l e a d i t s , a b o u t 9 m e t r e s l o n g a r e p a r a l l e l t o a major j o i n t d i r e c t i o n (012 d e g r e e s ) . O t h e r w o r k i n g s i n t h e immediate v i c i n i t y have been f l o o d e d by t h e c r e e k and a r e o b s e r v a b l e when w a t e r l e v e l s a r e low (V. P r e t o , p e r s . comm., 1 9 8 4 ) . This s e c t i o n i s composesd o f s u l p h i d e - r i c h s e r i c i t e s c h i s t i n f a u l t c o n t a c t w i t h an impure l i m e s t o n e u n i t . S t r u c t u r e : A w e l l developed f o l i a t i o n p a r a l l e l t o bedding s t r i k e s e a s t - w e s t and d i p s v a r i a b l y t o t h e s o u t h and n o r t h . A superimposed north s t i k i n g , s h a l l o w l y e a s t - d i p p i n g c r e n u l a t i o n c l e a v a g e i s p r o n o u n c e d on o u t c r o p s near t h e c r e e k . Early m e s o s c o p i c recumbent i s o c l i n a l f o l d s w i t h a x i a l p l a n e s p a r a l l e l t o t h e p r o n o u n c e d s c h i s t o s i t y and a x e s p l u n g i n g p a r a l l e l t o t h e m i n e r a l l i n e a t i o n , p r o b a b l y i n d i c a t e a l a r g e s t r u c t u r e which c o n t r o l s t h e d i s t r i b u t i o n o f t h e s t r a t i f o r m m i n e r a l i z e d zones ( P r e t o , p e r s . comm., 1984). M i n e r a l i z a t i o n : M i n e r a l occurrences a r e s t r a t i f o r m massive p y r i t e d e p o s i t s w i t h m i n o r c h a l c o p y r i t e s p h a l e r i t e and g a l e n a . S u l p h i d e s o c c u r as m a s s i v e pods (up t o 1m t h i c k ) , a s l a y e r s (up t o 10cm t h i c k ) and as f r a g m e n t s i n s i l i c i f i e d b r e c c i a . Sulphide m i n e r a l i z a t i o n i s composed m a i n l y o f w e l l - f o r m e d b u t d i s r u p t e d p y r i t e g r a i n s ( a v e r a g e s i z e 2.5mm a c r o s s ) w i t h m i n o r c h a l c o p y r i t e i n an a n k e r i t i c q u a r t z m a t r i x . This unit looks like a pyrite-silica exhalite. L o c a l l y the sulphide horizons a r e w e l l l a y e r e d ( l a y e r s a r e 8cm t h i c k o v e r an e x p o s e d t h i c k n e s s o f 3.5m). A t t i t u d e s o f l a y e r i n g and c o i n c i d e n t f o l i a t i o n a r e t h e same as t h o s e o b s e r v e d i n t h e l i m e s t o n e . Most m i n e r a l i z a t i o n a p p e a r s t o be s t r a t a b o u n d and s y n g e n e t i c w i t h t h e host f e l s i c s c h i s t s . Sample d e s c r i p t i o n : C o l l e c t e d samples c o n s i s t o f f i n e g r a i n e d galena d i s s e m i n a t e d through massive i r o n s u l p h i d e h o r i z o n s . V e i n m a t e r i a l , a l s o a n a l y s e d , c o n t a i n s c o a r s e r g a l e n a and s p h a l e r i t e i n q u a r t z gangue. Reference:  GOUTIER e t a l , 1985.  133  ENARGITE: A l s o known a s : N o r t h S t a r , Ace M i n f i l e number: 082M-064, 065 Map number: 004; L a t . 51.35ON Production  Long.  as l i s t e d i n M i n f i l e : From t h e s o u t h showing  31  of o r e  (1954)  5 tonnes of ore  (1972)  280 1 ,561 From  the  north  showing  119.99ow  tonnes g kg  3,452 g 1,341 kg 651 kg  Ag Cu  AG Pb Zn  L o c a t i o n : The p r o p e r t y a t t h e head of B i r k C r e e k summit between t h e v a l l e y of B a r r i e r e C r e e k and t h e N o r t h Thompson R i v e r .  i s at  the  H o s t r o c k : The E n a r g i t e v e i n o c c u r s a t , o r a d j a c e n t t o , t h e c o n t a c t between a f i n e g r a i n e d m e t a - s e d i m e n t a r y p a c k a g e o f t h e E a g l e Bay F o r m a t i o n (composed o f p h y l l i t e , s l a t e , i n t e r b e d d e d s i l t s t o n e and s a n d s t o n e , and v a r i o u s l i m e s t o n e h o r i z o n s , s u b u n i t E B P l ) , and t h e m e t a - b a s a l t o f t h e F e n n e l l F o r m a t i o n (lFu). S t r u c t u r e : The v e i n s t r i k e s N15ow and d i p s 45ow. The r o c k s the area s t r i k e almost v e r t i c a l l y ; near the v e i n the host rocks are h i g h l y d i s t u r b e d .  in  M i n e r a l i z a t i o n : The s u l p h i d e s a r e h o s t e d by a s t r o n g q u a r t z v e i n (45cm wide) b o r d e r e d by gouge m a t e r i a l p r o b a b l y r e l a t e d t o a f a u l t between t h e two f o r m a t i o n s a b o v e . The s u l p h i d e s , m a i n l y g a l e n a , a r e i r r e g u l a r l y d i s t r i b u t e d and o c c u r i n p o c k e t s . L o c a l l y d i s s e m i n a t e d s u l p h i d e s o c c u r i n the a d j a c e n t carbonate host rocks. Sample d e s c r i p t i o n : C o a r s e g a l e n a i n q u a r t z v e i n was o t h e r s u l p h i d e s were p r e s e n t i n t h e s a m p l e . References:  BCDM EXPL. IN BC. 1978, pp. BCDM GEM 1974 , p. 97. BCDM MMAR 1927, p. 190.  E108.  sampled;  no  134  FORTUNA: A l s o known a s : Kuno M i n f i l e number: 082M-070 t o 072 Map number: 013; L a t . 51.37C-N  Long.  119.93ow  L o c a t i o n : The p r o p e r t y i s on t h e f l a n k o f F o r t u n a h i l l . The a l u m i n i u m r o o f o f an o l d c a b i n on t h e p r o p e r t y i s v i s i b l e from g r e a t d i s t a n c e and c a n be u s e d t o g u i d e a c c e s s t o t h e w o r k i n g s along o l d t r a i l s . H o s t r o c k : Q u a r t z l e n s e s ( o r v e i n segments) c u t t h r o u g h l i g h t t o d a r k g r e e n c h l o r i t i c p h y l l i t e s , s i l s t o n e , l i m e s t o n e and quartzite (EBU). The s c h i s t s c l o s e t o t h e s e l e n s e s a r e v e r y a l t e r e d and i n p l a c e s s i l i c i f i e d . S t r u c t u r e : The f o l i a t i o n i n t h e h o s t r o c k s s t r i k e s a t N45ow and d i p s 24o t o t h e s o u t h w e s t . The o v e r a l l s t r i k e o f t h e m i n e r a l i z e d bodies p a r a l l e l s the f o l i a t i o n . M i n e r a l i z a t i o n : S c a t t e r e d pockets of galena occur i n the quartz. The v a r i o u s m i n e r a l i z e d z o n e s a r e more o r l e s s p a r a l l e l t o each o t h e r , and a l t h o u g h t h e y o c c u r a t s e v e r a l p l a c e s on t h e s l o p e o f t h e h i l l , t h e i r c o n t i n u i t y has n o t been d e t e r m i n e d . Sample d e s c r i p t i o n : W e l l c r y s t a l l i z e d g a l e n a a s s o c i a t e d w i t h m i n o r amounts o f p y r i t e was sampled from one o f t h e s e b o d i e s o c c u r i n g near t h e o l d w o r k i n g s . References:  BCDM MMAR 1927, p. 190.  135  WHITE ROCK: M i n f i l e number: 082M-066 M i n e r a l I n v e n t o r y number: 82M5-PB1 Map number: 028; L a t . 51.30ON Long. G r a d e as l i s t e d Composite  119.91ow  i n BCDM MMAR 1950: sample: 0.3 4 g / t Au 91.80 g / t Ag 2.2 % Pb 0.8 % Zn  L o c a t i o n : The d e p o s i t i s a p p r o x i m a t i v e l y 1.6km e a s t , and 500 t o 800 m e t r e s above B a r r i e r e R i v e r a t t h e s o u t h end o f N o r t h Barriere'Lake. H o s t Rock: The m i n e r a l i z a t i o n i s h o s t e d by t h e T s h i n a k i n l i m e s t o n e (EBGt) w h i c h o c c u r s i n t e r d i g i t a t e d w i t h g r e e n c a l c a r e o u s c h l o r i t i c s c h i s t (EBG). Structure: The main f r a c t u r e s y s t e m w h i c h h o s t s t h e v e i n s s t r i k e s n o r t h e a s t e r l y and c u t s t h e l i m e s t o n e a t h i g h a n g l e s . T h e s e f r a c t u r e s h a v e been i n t e r r u p t e d by l a t e f a u l t s b o t h a l o n g and a c r o s s t h e p l a n e o f t h e i n f i l l i n g v e i n s (BCDM, 1 9 5 0 ) . A l a r g e number o f s m a l l v e i n s , e x p o s e d on s u r f a c e , a r e o f i r r e g u l a r w i d t h and o f unknown l e n g t h . T h e s e v e i n s g e n e r a l l y s t r i k e N10OS a n d d i p s t e e p l y t o t h e e a s t . M i n e r a l i z a t i o n : Q u a r t z v e i n s , c l o t s and s t r i n g e r s , c a r r y i n g mainly a r g e n t i f e r o u s galena, occur i n a s e r i e s of f r a c t u r e s w h i c h a r e p r o b a b l y r e l a t e d t o the main f a u l t zone a l o n g t h e B a r r i e r e R i v e r v a l l e y . I n s e v e r a l p l a c e s the c o n t a c t of t h e l i m e s t o n e and t h e s u r r o u n d i n g s c h i s t i s a l s o w e l l m i n e r a l i z e d . The v e i n s a r e o f i r r e g u l a r l e n g t h ; w i d t h s v a r y from 5cm t o 45cm. Sample d e s c r i p t i o n : C o n c e n t r i c g a l e n a b l e b s s u r r o u n d e d by a q u a r t z - c a l c i t e gangue was s a m p l e d from a v e i n on t h e p r o p e r t y . References:  ECONOMIC GEOLOGY SERIES NO. 8, GSC 1930, BCDM MMAR 1950, pp. 111-112. BCDM MMAR 1928, p . 212. BCDM MMAR 1927, p . 189.  p.  302.  1 36  JUNE KAJUN: A l s o known a s : R e n n i n g s , K a j u n . M i n f i l e number: 082M-058 Map number: 021; L a t . 51.26QN  Long.  119.80OW  L o c a t i o n : A l a r g e n o r t h - s o u t h t r e n c h (120m long) exposed a m i n e r a l i z e d v e i n on t h e s o u t h e a s t s i d e of E a s t B a r r i e r e Lake t h e mouth of D e a d f a l l C r e e k .  at  H o s t r o c k : A f o l d e d m i n e r a l i z e d v e i n i s h o s t e d by g r e y t o w h i t e l i m e s t o n e (EBGl) a s s o c i a t e d w i t h b l a c k g r a p h i t i c p h y l l i t e . A l a r g e f a u l t , n e a r t h e b a s e of t h e e x p o s u r e i n t h e t r e n c h , i s u n d e r l a i n by b l a c k s i l i c e o u s and l i m y gouge and by unconsolidated breccia. Above t h e v e i n , t h e l i m e s t o n e i s not d i s t u r b e d and s t r i k e s from N20ow t o 45ow w i t h d i p s n e a r 4 0 O E . S t r u c t u r e : The m i n e r a l i z e d v e i n i s a s s o c i a t e d w i t h a p o s s i b l e f a u l t i n d i c a t e d by t h e p r e s e n c e of gouge m a t e r i a l . The v e i n s t r i k e s N70ow and d i p s 65osw. In s e v e r a l p l a c e s m i n e r a l i z a t i o n is concentrated i n the c r e s t s of s m a l l drag f o l d s . M i n e r a l i z a t i o n : I n t h e c r e s t of a open l a r g e f o l d a m i n e r a l i z e d zone, a p p p r o x i m a t i v e l y 7m l o n g by 4m h i g h , i s composed of s i l i c e o u s c a l c i f i c and d o l o m i t i c gangue c o n t a i n s e c t i o n s up t o 1.3m t h i c k w h i c h a r e m i n e r a l i z e d w i t h g a l e n a , s p h a l e r i t e and minor c h a l c o p y r i t e . P a t c h e s and s t r e a k s of s p h a l e r i t e , g a l e n a , c h a l c o p y r i t e and p y r i t e e x t e n d l o c a l l y i n t o the s u r r o u n d i n g limestone. Sample D e s c r i p t i o n : W e l l c r y s t a l l i z e d but f i n e g r a i n e d g a l e n a a s s o c i a t e d w i t h p y r i t e and s p h a l e r i t e was sampled from the e x p o s e d q u a r t z mass. The samples were c o l l e c t e d b o t h a d j a c e n t and 5m away from t h e gouge r i c h z o n e . R e f e r e n c e s : BCDM ASS.  RPT.  2232,  2230.  to  1 37  LEEMAC: A l s o known a s : Boomac. M i n f i l e number: 082M-056 Map number: 046; L a t . 51.35ON  Long.  119.70ow  L o c a t i o n : The Leemac g r o u p o f c l a i m s a r e a c c e s s i b l e by l o g g i n g r o a d s f r o m t h e e a s t s i d e o f t h e town o f B a r r i e r e . The c l a i m s a r e a l o n g F e n n e l l Creek. H o s t r o c k : The v e i n o c c u r w i t h i n t h e C r e t a c e o u s B a l d y b a t h o l i t h . Near t h e v e i n t h e i n t r u s i o n i s p o r p h y r i t i c , r e d d i s h i n c o l o r and n e a r l y d e v o i d of mafic m i n e r a l s . S e r i c i t e i s l o c a l l y abundant i n the v i c i n i t y of the v e i n s t r u c t u r e . Narrow m a f i c dykes ( s t r i k i n g p a r a l l e l t o t h e m i n e r a l i z e d v e i n and d i p p i n g t o t h e north) occur throughout the b a t h o l i t h . S t r u c t u r e : The v e i n s t r i k e s N 2 5 O E w i t h a m o d e r a t e d i p t o t h e northwest. I t i s b o r d e r e d on b o t h s i d e s by f a u l t gouge, i n d i c a t i n g t h a t t h e v e i n has been s u b j e c t e d t o movement o r t h a t i t f i l l s a s h e a r zone r e l a t e d t o a f a u l t i n g e v e n t . M i n e r a l i z a t i o n : The m i n e r a l i z a t i o n i s h o s t e d by a w e l l d e l i n e a t e d q u a r t z v e i n h a v i n g an a v e r a g e w i d t h o f 90cm. The s u l p h i d e s , p y r i t e , s p h a l e r i t e and g a l e n a , a r e c o a r s e and w e l l c r y s t a l l i z e d . T h i s m i n e r a l i z e d v e i n i s s u r r o u n d e d by a s u b s i d i a r y v e i n system mostly b a r r e n of s u l p h i d e minerals. References:  BCDM ASS. RPT. 59 39.  BROKEN RIDGE: A l s o known a s : May. M i n f i l e number: 082M-130 Map number: 009; L a t . 51.350N Location: northwest  Long.  119.88ow  The m i n e r a l i z e d zone o c c u r s on H a r p e r C r e e k o f t h e west end o f N o r t h B a r r i e r e L a k e .  2km  D e s c r i p t i o n : L e n s e s and b l e b s o f p y r i t e and p y r r h o t i t e w i t h m i n o r amounts o f c h a l c o p y r i t e , s p h a l e r i t e and t r a c e o f g a l e n a occur semi-conformably with the f o l i a t i o n i n the c h l o r i t i c member o f t h e q u a r t z - s e r i c i t e s c h i s t u n i t EBA. Numerous i r o n gossans i n t h e area a r e r e l a t e d t o abundant i r o n s u l p h i d e s ( p y r i t e and p y r r h o t i t e ) i n t h e s c h i s t . Sample d e s c r i p t i o n : The d a t a u s e d come f r o m a n a l y s e s made by t h e G e o l o g i c a l s u r v e y o f Canada, a n a l y s e no. G79BN-001. References:  BCDM EXPL. i n BC 1976, p. E62 BCDM GEM 1971, p. 440.  1 38  BIRCH ISLAND-CLEARWATER  AREA:  CHU-CHUA: M i n f i l e number: 092P-140 Map number: 003; Lat. 5 1 . 3 8 O N  L o n g . 120.07OW  L o c a t i o n : The Chu-Chua p r o p e r t y i s a p p r o x i m a t i v e l y 20km n o r t h n o r t h w e s t from t h e town of B a r r i e r e , on t h e r i d g e e a s t of Chu-Chua m o u n t a i n . H o s t Rock: The d e p o s i t i s h o s t e d i n t h e u p p e r s t r u c t u r a l d i v i s i o n of t h e F e n n e l l F o r m a t i o n ( u f b ) composed m a i n l y of b a s a l t w i t h a l k a l i c a f f i n i t i e s ( A g g a r w a l l e t a_l. , 1984), i n w h i c h p r i m a r y t e x t u r e s and p i l l o w s (1 t o 3m a c r o s s ) a r e s t i l l visible. The m a r g i n s of t h e p i l l o w s a r e s l i g h t l y c h i l l e d and are c h l o r i t i z e d or b l e a c h e d . M a s s i v e t a l c z o n e s and s i l i c e o u s r o c k s are l o c a l l y abundant w i t h i n t h i s package, p a r t i c u l a r i l y near the s u l p h i d e r i c h zones. C h e r t and/or t u f f i t e o v e r l i e t h e m i n e r a l i z a t i o n and a r e b e l i e v e d t o be e x h a l a t i v e i n o r i g i n (Aggarwall e t a l . , 1984). S t r u c t u r e : R o c k s of t h e F e n n e l l F o r m a t i o n a r e g e n e r a l l y not highly foliated. The s c h i s t o s i t y , were d e v e l o p e d , i s a x i a l planar to e a r l y , g e n e r a l l y northeast plunging i s o c l i n a l f o l d s . Two g e n e r a t i o n s of l a t e r f o l d s ( e a s t e r l y and northwesterly t r e n d i n g , S c h i a r i z z a , 1980) r e f o l d e d t h e main s c h i s t o s i t y and may be r e s p o n s i b l e f o r r e p e t i t i o n of t h e m i n e r a l i z e d h o r i z o n s . M i n e r a l i z a t i o n : The b a s a l t c o n t a i n s two major ( e a s t e r n and w e s t e r n ) , and two minor l e n t i c u l a r b o d i e s o f m a s s i v e s u l p h i d e s t h a t a p p e a r t o be s t r a t a b o u n d . In g e n e r a l the d e p o s i t s trend n o r t h - s o u t h , d i p s t e e p l y w e s t , and p l u n g e g e n t l y s o u t h . The s u l p h i d e s are i n sharp c o n t a c t with the hangingwall r o c k s , but t h e e x t e n s i o n of t h e b o d i e s down d i p a r e i r r e g u l a r and i n s e v e r a l p l a c e s l e n s o u t i n t o c h e r t y r o c k s ( M c M i l l a n , 1980). The m i n e r a l i z e d zones a r e a s s o c i a t e d w i t h m a s s i v e t a l c m a g n e t i t e l e n s e s , and a r e composed m a i n l y of p y r i t e and c h a l c o p y r i t e w i t h m i n o r s p h a l e r i t e , c u b a n n i t e , s t a n n i t e , and q u a r t z and c a l c i t e . B e d d i n g i s n o t common and o c c u r s o n l y l o c a l l y where i t i s o u t l i n e d by c h a l c o p y r i t e - r i c h l a y e r s o r by a l t e r n a t i n g l a y e r s of p y r i t e of d i f f e r e n t s i z e s . The m a s s i v e s u l p h i d e s a r e c u t by q u a r t z - t a l c v e i n s and, i n one h o l e , by m o l y b d e n i t e s t r i n g e r s ( M c M i l l a n , 1980).  139  The Chu-Chua d e p o s i t i s b e l i e v e d by A g g a r w a l l e t a_l. (1984) t o r e p r e s e n t d e p o s i t i o n from s a t u r a t e d s o l u t i o n on t h e s e a f l o o r a n d / o r n e a r b y seamounts. The d i f f e r e n t l e n s e s f o r m e d from d i f f e r e n t vent sources. The a s s o c i a t e d m a g n e t i t e and t a l c r i c h zones p r o b a b l y r e p r e s e n t a r e a s where a h i g h e r component o f s e a - w a t e r was i n v o l v e d i n a l t e r a t i o n and m i n e r a l i z a t i o n . S i m i l a r l y t h e a p p a r e n t l a c k o f f o o t w a l l a l t e r a t i o n i s most l i k e l y due t o a l a c k o f s i g n i f i c a n t i n t e r a c t i o n between t h e h y d r o t h e r m a l s o l u t i o n and t h e h o s t r o c k s . Sample d e s c r i p t i o n : L e a d d a t a r e f e r r e d t o i n t h e p r e s e n t s t u d y a r e from A g g a r w a l l and N e s b i t t ( 1 9 8 4 ) . T h e i r a n a l y s e d l e a d was e x t r a c t e d f r o m p y r i t e and c h a l c o p y r i t e r a t h e r t h a n g a l e n a and t h e d a t a a r e o n l y u s e d h e r e on a c o m p a r a t i v e b a s i s . R e f e r e n c e s : AGGARWALL,P.K.,and NESBITT,B.E. 1984. AGGARWALL,P.K.,FUJJI,T.,and NESBITT,B.E. 1984. MCMILLAN,W.C. 1980.  140  F  O  G  H  O  R  N  :  A l s o known a s : Gopher, Shamrock M i n f i l e number: 082M-008, 029, 030, 040, 108 M i n e r a l I n v e n t o r y number: 82M12-Cu2, Ag1 Map number: 005; Lat. 51.54ON L o n g . 119.93ow Production  as  listed  in Minfile:  F o g h o r n 73 (1916-17)  tonnes  88,364 g 57,276 kg  of  ore  Ag Pb  L o c a t i o n : The p r o p e r t y i s a t a p p r o x i m a t i v e l y 2,000m e l e v a t i o n F o g h o r n M o u n t a i n , 6.5km s o u t h of B i r c h I s l a n d .  on  H o s t Rock: The p r o p e r t y i s u n d e r l a i n by r u s t y w e a t h e r e d f e l d s p a r - c h l o r i t e s c h i s t and s e r i c i t i c q u a r t z i t e s ( E B F q ) , b u t t h e m i n e r a l i z e d v e i n s a r e h o s t e d by s i l i c e o u s and l i m y s c h i s t s . The B a l d y b a t h o l i t h , e x p o s e d i n t h e s o u t h e r n p a r t of the p r o p e r t y a t G r a n i t e M o u n t a i n , i s s u r r o u n d e d by f i n e t o medium g r a i n e d b i o t i t e q u a r t z g n e i s s w i t h i n t e r l a y e r e d a m p h i b o l i t e and p e l i t i c hornfels. F e l s i c p o r p h y r y d y k e s o c c u r n e a r the m i n e r a l i z e d zones and may be r e s p o n s i b l e f o r b o t h t h e s i l i c i f i c a t i o n of t h e h o s t r o c k s and f o r t h e s u l p h i d e v e i n s . S t r u c t u r e : The F o g h o r n s h o w i n g s a r e l o c a t e d on t h e n o r t h e r n l i m b of an e a s t - w e s t s t r i k i n g a n t i f o r m i n v e r y c l o s e p r o x i m i t y t o a major n o r t h e r l y s t r i k i n g t h r u s t f a u l t . The n o r t h e a s t e r l y s t r i k e of the v e i n i s at a h i g h angle to the t h r u s t f a u l t . Small s c a l e s t r u c t u r e s , d r a g f o l d s f o r example, i n d i c a t e t h a t o r i g i n a l b e d d i n g has been d e f o r m e d and p r o b a b l y t r a n s p o s e d i n t o t i g h t i s o c l i n a l f o l d s now seen as f o l i a t i o n ( s t r i k i n g N 3 0 O E and d i p p i n g 80ow). M i n e r a l i z a t i o n : Q u a r t z v e i n segments o c c u r t h r o u g h o u t t h e s c h i s t ; t h e i r d i s t r i b u t i o n i s n o t c o n t i n u o u s and may t h e r e f o r e r e p r e s e n t a s y s t e m of s m a l l v e i n s r a t h e r t h a n a major s i n g l e discontinuous vein. T h e s e v e i n segments a r e l o c a l l y h e a v i l y m i n e r a l i z e d w i t h g a l e n a , s p h a l e r i t e and p y r i t e . In p l a c e s c h a l c o p y r i t e a l s o o c c u r s b u t o n l y i n m i n o r amounts ( d i s s e m i n a t e d c h a l c o p y r i t e i s f o u n d i n g r e a t e r amounts i n t h e n e a r b y L y d i a prospect). The w i d t h of t h e v e i n segments i s a p p r o x i m a t l y 35cm; t h e y s t r i k e a b o u t N 3 5 O E and d i p i n v a r i o u s d i r e c t i o n s — s o m e of them a r e v e r t i c a l . Sample D e s c r i p t i o n : Samples were c o l l e c t e d from t h e o l d w o r k i n g s . The g a l e n a o c c u r s w i t h m i n o r amounts of s p h a l e r i t e p y r i t e i n q u a r t z gangue s p e c i m e n s . References:  BCDM ASS. RPT. 11381, BCDM OPEN F I L E .  3820.  and  141  REXSPAR: A l s o known a s : S m u g g l e r , S p a r , B l a c k Diamond M i n f i l e number: 082M-021 M i n e r a l I n v e n t o r y number: 082M12-U1, FSP1 Map  number;  016  Lat.  51.570N  Long.  119.90OW  R e s e r v e s as l i s t e d i n M i n f i l e : R e x s p a r , t o t a l d e p o s i t ( d e c . 1976): 1,114,000 @ 1.55% U cut o f f used.  tonnes  L o c a t i o n : The R e x s p a r d e p o s i t 5km, s o u t h of B i r c h I s l a n d , t h e s o u t h s l o p e of t h e N o r t h Thompson v a l l e y between L u t e Foghorn Creeks.  i s on and  H o s t Rock: M i n e r a l i z a t i o n a t R e x s p a r i s d i r e c t l y a s s o c i a t e d w i t h t h e t r a c h y t i c member of t h e f e l s i c u n i t EBA. The t r a c h y t e i s m a s s i v e or b r e c c i a t e d and s t r o n g l y f o l i a t e d . The surrounding r o c k s , c h l o r i t e s e r i c i t e s c h i s t and s i l v e r y s e r i c i t e - q u a r t z i t e , c o n t a i n e x p o s u r e s of c l e a r l y r e c o g n i z e a b l e d a c i t i c and a n d e s i t i c volcanic breccia. S t r u c t u r e : The r o c k s of t h e t r a c h y t e s u i t e e x h i b i t b r e c c i a t i o n , c a t a c l a s i s and m y l o n i t i z a t i o n s t r u c t u r e s . The f o l i a t i o n i n the r o c k s s t r i k e s n o r t h - e a s t e r l y w i t h a 300 d i p t o t h e n o r t h w e s t . The m i n e r a l i z e d zones a r e d e f o r m e d and a r e n e a r t o s e v e r a l f a u l t s and t h r u s t s . M i n e r a l i z a t i o n : The two main m i n e r a l i z e d zones p r e s e n t a t R e x s p a r a r e : 1) an u r a n i u m r i c h zone c o n f i n e d t o t u f f a c e o u s and a r g i l l i t i c l e n s e s c o n t a i n i n g abundant p y r i t e a s s o c i a t e d with a g g r e g a t e s of u r a n i u m b e a r i n g f l u o r p h l o g o p i t e . The l e n s e s a r e d i s c o n t i n u o u s , a v e r a g e 20cm i n t h i c k n e s s , and a r e c o n f o r m a b l e w i t h t h e s c h i s t o s i t y of t h e h o s t t r a c h y t e . 2) a f l u o r i t e zone, b a r r e n of b o t h t h o r i u m and u r a n i u m , i s m i n e r a l i z e d w i t h c e l e s t i t e , p y r i t e , t r a c e of g a l e n a and molybdenite. The m i n e r a l i z a t i o n a t R e x s p a r has been i n t e r p r e t e d by P r e t o (1978, i n BCDM G e o l o g y ) as r e s u l t i n g from d e p o s i t i o n from a l a t e s t a g e d e u t e r i c v o l a t i l e r i c h f l u i d e v o l v e d from the h i g h l y d i f f e r e n t i a t e d i n t r u s i v e - e x t r u s i v e igneous s u i t e . However, b e c a u s e C02 a p p a r e n t l y p l a y e d an i m p o r t a n t r o l e i n t h e t r a n s p o r t and d e p o s i t i o n of u r a n i u m a s s o c i a t e d w i t h h y d r o t h e r m a l s o l u t i o n s ( M o r t o n , 1978), t h e n t h e u r a n i u m and t h o r i u m m i n e r a l i z a t i o n c o u l d be s y n g e n e t i c w i t h t h e t r a c h y t e u n i t .  1 42  Sample d e s c r i p t i o n : No samples were c o l l e c t e d from t h e R e x s p a r d e p o s i t by t h e w r i t e r . The d a t a r e f e r r e d t o h e r e came from a n a l y s e s by t h e G e o l o g i c a l S u r v e y o f Canada (sample number G79SA-001. R e f e r e n c e s : GSC paper 78-1B, pp. 137-140. BCDM G e o l o g y i n BC 1977-1981, pp. 44-56 CIM B u l l . , 71, 1978, pp. 82. MORTON, R.D., AUBUT, A., GANDHI, S.S. 1978. R e x s p a r D e p o s i t . G e o l o g i c a l S u r v e y o f Canada, C u r r e n t R e s e a r c h , p a p e r 78-1B, pp. 137-140.  143  MT McCLENNAN AREA D e p o s i t names: Red T o p , Mt M c C l e n n a n , S u n r i s e ( N a o m i ) . A l s o known a s : M i m s i c C l a i m s M i n f i l e number: 082M-044, 046 M i n e r a l I n v e n t o r y number: 82M12-PB1 Map n u m b e r s : 531, 5 3 9 , 541; L a t . 51.64QN L o n g . 119.78ow L o c a t i o n : T h i s area comprises t h r e e o l d p r o s p e c t s near the summit of t h e M c C l e n n a n M o u n t a i n l o c a t e d a b o u t 7.5km n o r t h e a s t of B i r c h I s l a n d . A l l the showings are a c c e s s i b l e v i a f o r e s t r y roads. H o s t R o c k : The m i n e r a l i z e d o c c u r r e n c e s of t h e Mt M c C l e n n a n a r e a a r e h o s t e d by g r e e n s c h i s t and by c a l c a r e o u s c h l o r i t i c and g r a p h i t i c s c h i s t i n t e r c a l a t e d w i t h minor q u a r t z i t e siliceous s c h i s t and c a r b o n a t e (EBQ). G r a n i t i c r o c k s c r o p o u t about 2km n o r t h o f t h e s h o w i n g s ; t h e c o n t a c t between t h e i n t r u s i o n and t h e s c h i s t s i s marked by t h e d e v e l o p m e n t o f h o r n f e l s i c r o c k s and by s k a r n zones i n c a r b o n a t e - r i c h h o r i z o n s . L a m p r o p h y r e dykes o c c u r i n t h e w e s t e r n end o f t h e a r e a . S t r u c t u r e : R o c k s i n t h e v i c i n i t y of M c C l e n n a n M o u n t a i n a r e h i g h l y f o l i a t e d and a r e f o l d e d a r o u n d a s t r o n g e a s t e r l y t r e n d i n g open a n t i f o r m p l u n g i n g 1 5 O E . The s o u t h l i m b o f t h e a n t i f o r m has been d i s l o c a t e d by f a u l t i n g and g r a n i t i c i n t r u s i o n . M i n e r a l i z a t i o n : P b - Z n - A g and Cu o c c u r r e n c e s a r e w i d e s p r e a d t h e a r e a , t h e t h r e e o l d w o r k i n g s sampled f o r t h e p r e s e n t study a r e : 1) t h e e a s t e r n a r e a t h a t c o m p r i s e d t h e o l d S u n r i s e g r o u p Naomi c l a i m s . The m i n e r a l i z a t i o n c o n s i s t s o f p y r r h o t i t e p y r i t e w i t h g a l e n a and s p h a l e r i t e o c c u r i n g i n q u a r t z i t i c as l e n t i c u l a r s h e e t s t r a c e a b l e on s u r f a c e o v e r a d i s t a n c e 125m a l o n g s t r i k e . The s h e e t s v a r y i n t h i c k n e s s from .3 and a r e n o t t o t a l l y c o n f o r m a b l e w i t h t h e e n c l o s i n g h o s t .  in  and and rocks of t o 1.2m  2) t h e c e n t r a l a r e a h o s t s t h e MT M c C l e n n a n (Snow) s h o w i n g . T h i s showing c o n t a i n s m a s s i v e and s e m i - m a s s i v e h e a v i l y o x i d i z e d p y r i t e w i t h g a l e n a , s p h a l e r i t e and m i n o r amounts of c h a l c o p y r i t e i n impure l i m y h o r i z o n s . The s u l p h i d e r i c h l a y e r s a r e up t o 50cm t h i c k and p a r a l l e l t h e s c h i s t o s i t y and c o m p o s i t i o n a l l a y e r i n g of the s c h i s t s . A magnetite bearing skarn is developed b e l o w an a d j a c e n t p r o m i n e n t bed o f c r y s t a l l i n e l i m e s t o n e .  144  3) t h e w e s t e r n a r e a h o s t s t h e Red Top showing which c o n s i s t s o f g a l e n a and s p h a l e r i t e a s s o c i a t e d w i t h s i l i c i f i e d p y r i t i c z o n e s o c c u r i n g along bedding i n limestone. C h a l c o p y r i t e f i l l s many g a s h - l i k e openings. The s u l p h i d e s have an e r r a t i c d i s t r i b u t i o n a l o n g s t r i k e , o c c u r i n g i n blows and seams. N e v e r t h e l e s s they a r e s t r a t a b o u n d t o a d e f i n i t e s t r a t i g r a p h i c h o r i z o n composed o f c a l c a r e o u s q u a r t z s e r i c i t e s c h i s t a d j a c e n t t o an h o r i z o n t h a t v a r i e s from s k a r n t o c l e a r c r y s t a l l i n e l i m e s t o n e . I n g e n e r a l t h e s e m i n e r a l i z e d b o d i e s a p p e a r t o o c c u r as d i s c o n t i n u o u s l e n s e s (more o r l e s s c o n f o r m a b l e w i t h t h e s c h i s t o s i t y ) o r a s e r r a t i c s w e l l i n g s f o r m e d by l i m e s t o n e r e p l a c e m e n t a n d / o r s k a r n d e v e l o p m e n t due t o metasomatism probably r e l a t e d to the i n t r u s i o n of the Raft b a t h o l i t h . Samples  description:  1) e a s t e r n a r e a ( S u n r i s e ) : F i n e g r a i n e d h i g h l y a l t e r e d sample c o n t a i n i n g s p h a l e r i t e and g a l e n a a s s o c i a t e d w i t h a b u n d a n t pyrite. 2) c e n t r a l a r e a (Mt M c C l e n n a n ) : C o a r s e and f i n e g r a i n e d from d i s s e m i n a t i o n s from an a l t e r e d l i m y h o r i z o n . 3) w e s t e r n a r e a (Red T o p ) : Seams o f f i n e disseminated i n c h l o r i t i c s c h i s t . References:  grained  galena  sulphides  BCDM ASS. RPT. 6931, 6603, 5813, 436. BCDM G e o l o g y i n BC 1977-81, pp. 44-56.  145  VAVENBY: Map number: 042; L a t . 5 1 . 5 8 O N  Long. 119.75ow  D e s c r i p t i o n : Quartz v e i n c o n t a i n i n g narrow s u l p h i d e s seam (5cm wide) cut throught the T s h i n a k i n Limestone (EBGt). The v e i n i s m i n e r a l i z e d with galena and c o n t a i n s abundant c a l c i t e m a t e r i a l . A s y e n i t e dyke occurs i n the v i c i n i t y of the m i n e r a l i z e d v e i n . References: Paul S c h i a r i z z a , p e r s . comm., 1985.  PS-75-185: Map number: 04 8;  Lat. 5 1 . 5 8 O N  Long.  119.75ow  D e s c i p t i o n : Galena and s p h a l e r i t e occur i n a narrow quartz v e i n c u t t i n g the T s h i n a k i n Limestone, 4km east of the f o s s i l occurrence near Vavenby. References:  Paul S c h i a r i z z a , p e r s . comm., 1985.  SONJA: A l s o known as: LSD, V a l e n t i n e . M i n f i l e number: 092P-049 Map number: 044; Lat. 51.590N  Long. 120.0low  L o c a t i o n : T h i s small m i n e r a l i z e d showing occurs on the south bank of the North Thompson R i v e r , 1km east of the Clearwater railway s t a t i o n . D e s c r i p t i o n : Discontinuous s i l i c i f i e d lenses or veins c a r r y c r y s t a l l i n e galena and a n g l e s i t e . The m i n e r a l i z e d masses occur w i t h i n a quartz s e r i c i t i c s c h i s t wedge of the Eagle Bay Formation c l o s e t o the c o n t a c t with the F e n n e l l Formation. The m i n e r a l i z a t i o n appears t o f o l l o w the east s i d e of a major dyke (3.5 to 13m wide) which cuts the rocks of the Eagle Bay formation. References: BCDM EXPL. i n BC 1976, p. E132. BCDM GEM 1969, p. 230.  1 46  BIRCH ISLAND: M i n f i l e number: 082M-023 M i n e r a l I n v e n t o r y number: 82M12-PB2 Map Number: 040; Lat. 51.56ON Long. Production  as l i s t e d  119.90OW  i n M i n f i l e : 14 t o n n e s  o f o r e (1926):  6,566 g Ag 3,362 kg Pb L o c a t i o n : The o l d w o r k i n g s a r e l o c a t e d south of B i r c h I s l a n d .  a l o n g Foghorn Creek  road  D e s c r i p t i o n : E r a t i c galena m i n e r a l i z a t i o n occurs i n a f i s s u r e v e i n c u t t i n g t h r o u g h a q u a r t z i t i c member o f t h e f e l s i c u n i t (EBA). The f i s s u r e , s t r i k i n g n o r t h and d i p p i n g s t e e p l y west, i s b o r d e r e d by a zone i n w h i c h p y r i t e , s i d e r i t e and c a l c i t e a r e l o c a l l y abundant. The p r e s e n c e o f manganese o r e was a l s o r e p o r t e d from t h i s a r e a ( 1 9 3 1 ) . References:  TINDAL: Map number: Description: vein cutting References:  BCDM MMAR 1931, p . 107. BCDM MMAR 1929, p. C22 4.  043;  Lat. 51.60ON  Long.  119.78ow  G a l e n a was c o l l e c t e d i n an o l d a d i t from a q u a r t z q u a r t z s e r i c i t e s c h i s t o f t h e E a g l e Bay F o r m a t i o n . none a v a i l a b l e  1 47  APPENDIX B LABORATORY PROCEDURES FOR GALENA LEAD ISOTOPE ANALYSIS B.1  GALENA LEAD SAMPLE  PREPARATION  G a l e n a c r y s t a l s s e l e c t e d from r o c k o r o r e samples a r e s t o r e d i n p l a s t i c v i a l s . A p p r o x i m a t e l y 10 mg o f g r a i n s o f c l e a n g a l e n a a r e p i c k e d o u t , u s i n g a n e e d l e and a b i n o c u l a r m i c r o s c o p e , and put i n t o a d i s p o s a b l e 10 ml p o l y p r o p y l e n e b e a k e r . A c l e a n g l a s s b e a k e r (10 ml) i s w e i g h e d , t h e n t h e g a l e n a g r a i n s a r e e m p t i e d i n t o t h e g l a s s b e a k e r and t h e c o n t a i n e r i s r e w e i g h e d . The w e i g h t of t h e sample i n d i c a t e s t h e amount o f w a t e r t h a t must be added to the lead c h l o r i d e c r y s t a l s p r i o r to l o a d i n g . A p p r o x i m a t e l y 8 ml 2N H C l i s added t o t h e sample i n t h e g l a s s b e a k e r , w h i c h i s t h e n l e f t o v e r n i g h t on a h o t p l a t e . The lead sulphide i s converted to lead c h l o r i d e with the production of h y d r o g e n s u l p h i d e . The d r y P b C l 2 c r y s t a l s a r e r i n s e d i n 4N H C l t h r e e t i m e s . Most o f t h e i m p u r i t i e s a r e r e a d i l y d i s s o l v e d i n 4N H C l , b u t P b C l 2 i s l e a s t s o l u b l e a t t h i s n o r m a l i t y . C l e a n e d l e a d c h l o r i d e c r y s t a l s a r e d r i e d by r e t u r n i n g t h e b e a k e r t o t h e h o t p l a t e f o r a few m i n u t e s . A s o l u t i o n c o n t a i n i n g 1 ug Pb p e r 2 u l aqueous s o l u t i o n i s p r e p a r e d by a d d i n g a c a l c u l a t e d amount o f q u a r t z d i s t i l l e d w a t e r a l l o w i n g f o r t h e l o s s o f 30% o f t h e sample due t o n o n - d i s s o l u t i o n o f some o f t h e g a l e n a and l o s s o f lead c h l o r i d e during r i n s i n g .  B.2  PREPARATION  AND LOADING OF FILAMENTS  P r e - c l e a n e d r h e n i u m r i b b o n 1.5 cm l o n g i s s p o t - w e l d e d t o s i n g l e f i l a m e n t posts. A m i c r o p i p e t t e with disposable t i p s i s u s e d t o l o a d 2 u l o f sample o n t o e a c h f i l a m e n t , u s i n g a new t i p f o r e a c h sample. Samples a r e d r i e d a t 1 Amp. 4 u l o f s i l i c a g e l - p h o s p h o r i c a c i d s o l u t i o n i s l o a d e d on t o p o f t h e d r y s a m p l e . T h i s i s l e f t t o d r y a t 1.1 Amp, t h e n t h e c u r r e n t i s g r a d u a l l y i n c r e a s e d u n t i l t h e l o a d d i s s o l v e s and r e p r e c i p i t a t e s . When r e c r y s t a l l i z a t i o n i s complete, the c u r r e n t i s slowly increased u n t i l w h i t e smoke i s g i v e n o f f and t h e l o a d t u r n s w h i t e . The c u r r e n t c a n t h e n be t u r n e d up t o 2 Amps o r h i g h e r t o a l l o w t h e l o a d t o glow g e n t l y f o r a few s e c o n d s , t h e n o f f .  B.3 MASS SPECTROMETRIC PROCEDURES A l l t h e r e p o r t e d a n a l y s e s were done by F r a n c o i s e G o u t i e r i n the Geochronology L a b o r a t o r y a t the U n i v e r s i t y of B r i t i s h C o l u m b i a u s i n g a VG I s o t o p e s Isomass 54R mass s p e c t r o m e t e r l i n k e d t o a HP-85 m i c r o c o m p u t e r .  1 48  Samples were l o a d e d i n t o t h e mass s p e c t r o m e t e r , s i x a t a t i m e , and h e a t e d t o 11500-12500. The i s o t o p i c c o m p o s i t i o n i s m e a s u r e d u s i n g 'UBCGPB p r o g r a m s . Due t o t h e u n c e r t a i n i t y i n m e a s u r i n g 204pb peak, t h i s p r o g r a m measured t h e 204pb/207pb r a t i o t w i c e as o f t e n as t h e o t h e r two r a t i o s , i m p r o v i n g t h e s t a t i s t i c s on t h e r a t i o . 1  Raw d a t a i s c o n v e r t e d t o t h e 206pb/204pb, 207pb/204pb and 208pb/204pb r a t i o s , t h e n n o r m a l i z e d t o a b s o l u t e v a l u e s u s i n g c o r r e c t i o n f a c t o r s d e t e r m i n e d by r e p e a t e d a n a l y s e s of t h e B r o k e n H i l l S t a n d a r d ( T a b l e 3 . 1 ) . E a c h a n a l y s i s i s r e p o r t e d w i t h an a s s o c i a t e d e r r o r b a s e d on a c o m b i n a t i o n o f t h e f r a c t i o n a t i o n v a r i a t i o n between r u n s , t h e u n c e r t a i n i t y i n mass f r a c t i o n a t i o n f a c t o r s , and w i t h i n - r u n p r e c i s i o n . R e f e r e n c e s : Andrew, A. Ph.D T h e s i s i n p r e p a r a t i o n , U n i v e r s i t y of B r i t i s h Columbia.  149  APPENDIX  C  1 50  Adams P l a t e a u : Lead Isotope Data Sample No 30504-001  Deposit/Sample Name  Mt Anl  Qual  Pb6/4 J 6 / 4  Pb7/4 J7:4  Pb8/4 US/4  Pb6/7  *6/7  Pb6/B  H6/8  ENARGITE  GL FG  GOOO  19.101 0.01 15.692 0.01 38.993 0.02 1.21720 0.01 0.489849  30504-00102 ENARGITE  GL FG  GOOO  30504- AVG  GL FG  GOOO  19.090 0.03 15.688 0.03 38.981 0.03 1.216B7 0.00 0.489732 O.OO 19.096 0.02 15.690 0.02 38.987 0.05 1.21704 0.01 0.489791 0.01  ENARGITE N=2  30504/00101 ENARGITE 30505- 002  GL FG FAIR  FOGHORN  (SAMPLE 011)  GL FG  GOOD  30505-00201 FOGHORN  (SAMPLE O i l )  GL FG  GOOO  30505-003  FOGHORN  (VEIN 007)  GL FG  GOOD  30505-003D1 FOGHORN  (VEIN 007)  GL FG  FAIR  0.01  19.079 0.06 15.664 0.04 3B.875 0.07 1.21799 0.04 0.490772 0.04 19.190 0.03 15.708 0.03 39.140 0.04 1.22164 0.01 0.490291 0.02 19.202 0.03 15.693 0.03 39.077 0.03 1.22356 0.01 0.491389 0.01 19.225 0.04 15.713 0.03 39.146 0.05 1.22355 0.03 0.491108 0.03 19.213 0.12 15.728 0.12 39.189 0.12 1.22156 0.01 0.490262 0.01 19.196 0.03 15.701 0.03 39.109 0.03 1.22260 0.01 0.490840 0.02 0.08 39.168 0.08 1.22260 0.02 0.490685 0.02  30505-AVG2  FOGHORN N=2 (SAMPLE 011)  GL FG  GOOD  30505-AVG3  FOGHORN N=2 (VEIN 007)  GL FG  GO/FR 19.219 0.08 1 5.721  30505- AVG  FOGHORN N=4  GL FG  30505/001  FOGHORN  (SAMPLE 007)  GL FG  30505/001D1 FOGHORN  (SAMPLE 007)  GL FC  30507-00101 BECA (TQM)  GL FG  GD/FR 19.20B 0.05 15.711 0.05 39.138 38.537 18.915 0.41 15.516 0.41 38.959 FAIR 19.073 0.21 15.680 0.20 38.927 GOOD 19.148 0.02 15.703 0.02 3B.916 FAIR 19.148 0.05 15.705 0.02 3B.8B5 FAIR 19.134 0.05 15.695 0.05 38.909 FAIR 19.143 0.04 15.701 0.03 38.581 FAIR 19.033 0.06 15.633 0.06 38.979 GOOD 19.334 0.02 15.668 0.02 39.042 GOOO 19.344 0.02 1 5.6B7 0.01  30507-001D2 BECA (TOM)  GL FG  FAIR  30507- AVG  GL FG  GO/FR 19.339 0.02 15.660 0.02 39.016 0.02 1.23338 0.01 0.495669 0.01  AGATE BAY  GL FG  30506-00101 AGATE SAY  GL FG  30506-00102 AGATE BAY  GL FG  30506- AVG  GL FG  30506- 001  AGATE 5AY N=3  30505/001 D3 AGATE BAY  GL FG  30507- 001  GL FG  BECA (TDM)  BECA N=3  POOR  19.339 0.01  0.06 1.22258 0.02 0.490763 0.02 0.42 1.21908 0.07 0.490829 0.08 0.21 1.21643 0.05 0.489572 0.04 0.04 1.21938 0.01 0.491889 0.04 0.10 1 .21916 0.05 0.492018 0.08 0.05 1 .21912 0.01 0.492084  0.01  0.06 1.21922 0.02 0.491997 0.04 0.06 1.21749 0.02 0.492044 0.02 0.02 1.23393 0.01 0.496001  0.01  0.02 1.23317 0.01 0.495474  0.01  15.684 0.01 39.026 0.01 1.23300 0.01 0.495531  0.00  GL FG POOR  19.322 0.03 15.703 0.03 39.056 0.03 1.23049 0.01 0.494725 0.02  BIRK CREEK (SECTION X DUMP)  CL FG  GODD  18.948 0.02 15.718 0.02 38.661 0.03 1 .2054 B 0.01 0.487575  0.01  30508-00101 BIRK CREEK (SECTION X DUMP)  GL FG  FAIR  18.947 0.08 15.741  0.08 38.e56 0.08 1.20368 0.01 0.487617  0.01 0.01  30507/00103 BECA (TOM) 30508- 001  BIRK CREEK (SECTION X)  GL FG  GOOD  3050B-002D1 BIRK CREEK (5ECTI0N X )  GL FG  GOOD  18.904 0.03 15.71C 2.01 38.791 0.03 1.20328 0.03 0.487321 18.882 0.03 15.599 0.03 38.751 0.03 1.20275 0.01 0.487256  30508-00301 BIRK CREEK (SECTION 012)  GL FG  POOR  19.026 0.39 15.798 0.39 39.027 0.39 1.20433 0.01 0.487514 0.02  30506-004  18.896 0.02 15.705 0.01 3B.755 0.02 1 .20319 0.02 0.487565 0.01  30508-002  BIRK CREEK (VEIN SECT. 012)  0.01  GL FG  GODD  30508-00401 BIRK CREEK (VEIN SEC.012)  GL FD  POOR  18.949 0.14 15.741  0.05 36.987 0.16 1.20384 0.13 0.486037 0.07  30506-0C5  BIRK CREEK (NEAR BRIDGE)  GL FG  GOOD  18.eQ3 0.01  0.01 38.829 0.01  30508-506  BIRK CREEK (G79BA-001 )  GL BR  FAIR  18.878 0.06 15.708 0.13 38.B93 0.18 1.20182 0.00 0.486224 0.00 1B.669 0.08 15.722 0.16 38.834 0.18 1.20018 0.00 0.486737 0.00  15.721  1.20174 0.01 0.486577 0.00  30508-50601 BIRK CREEK (G79BA-002)  GL BR  FAIR  30508-AVG1  BIRK CREEK N=2 (SECT. DUMP)  GL FG  30508-AUG2  BIRK CREEK N=2 (SECT.X)  GL FG  GD/FR 18.948 0.05 15.730 0.05 38.859 0.05 1.20458 0.01 0.487448 0.01 GOOD 18.893 0.03 15.705 0.02 38.771 0.03 1.20302 0.02 0.487289 0.01  3050B-AVG4  BIRK CREEK N=2 (SECT. X )  GL FG  30508-AUG6  BIRK CREEK (G79BA-AVG)  GL BR  30508-AVG  BIRK CREEK N=10  30508/003  BIRK CREEK (SECTION 012)  GL G/R GD/FR 18.907 0.06 1 5.716 0.05 38.B48 0.09 1.20304 0.05 0.486692 0.05 GL FG FAIR 18.901 0.02 15.691 0.01 3B.744 0.02 1.20454 0.01 0.487849 0.01  GD/PR 18.923 0.08 15.723 0.03 38.871 0.09 1.20352 0.08 0.486801 0.04 FAIR IB.874 0.07 15.715 0.08 3B.863 0.18 1.20100 0.00 0.486477 0.00  3050S-SO1  BROKEN RIOGE (G79BN-001)  GL BR  FAIR  30511-001  HOMESTAKE  GL FG  FAIR  30511-002  HOMESTAKE  GL FG FAIR  30511-002D1 HOMESTAKE  GL FG GOOD  19.249 0.08 15.697 0.11 39.253 0.13 1 .22630 0.00 0.491221 0.00 18.776 0.05 15.696 0.05 3B.574 0.05 1.19619 0.01 0.4B6742 0.01 18.8B7 0.05 15.693 0.05 38.681 0.06 1.20350 0.00 0.488279 0.02 18.900 0.04 15.705 0.02 3B.717 0.05 1.20341 0.04 0.488150 0.01 18.827 0.00 15.719 0.00 38.621 0.00 1.19773 0.00 0.488325 0.00 18.878 0.08 15.687 0.17 38.533 0.18 1.20343 0.12 0.490766 0.12  30511-502  HOMESTAKE (KAMAO 70)  GL GSC FAIR  30511-501  HOMESTAKE (361-G79H0-001)  GL GSC FAIR  30511-AVG2  HOMESTAKE N=2  GL FG FAIR  0.488215 0.01  30511-AVG  HOMESTAKE N=5  GL  0.486452 0.07  30511/OOl D1 HOMESTAKE 30513-001  FORTUNA  30513-00101 FORTUNA  18.894 0.05 15.699 0.03 38.699 0.06 1.20346 0.02 FR/GO 18.854 0.06 15.700 0.10 38.626 0.12 1.20085 0.07 GL FG POOR 18.B69 0.19 15.770 0.19 38.779 0.19 1.19652 0.04 GL FG GOOO 19.118 0.02 15.716 0.01 39.000 0.02 1.21643 0.01 GL FG GOOD 19.132 0.02 15.726 0.02 39.035 0.02 1.21657 0.01  30513-AVG 30515-001  FORTUNA N=2 REA GOLD (MASS. SULPH.HORZ .)  GL FG GOOO  30515-002  REA GOLD (VEIN)  GL FG GOOD  GL FG FAIR  0.485569 0.02 0.490196 0.01 0.490128 0.01  0.02 39.018 0.02 1.21650 0.01 0.490162 0.01 18.859 0.04 15.709 0.04 38.766 0.05 1.20052 0.02 0.486467 0.02 18.852 0.01 15.6B0 0.01 3B.687 0.02 1.2022B 0.01 0.487299 0.02  19.125 0.02 15.721  1 51  Adams P l a t e a u : Lead Isotope Data Sample No  Deposit/Sample Name  Mt Anl  Qual  30515-002D1 REA GOLD (VEIN)  GL FG GOOD  30515-003 30515-AVG2  REA GOLD (BARITE HORZ.) REA GOLD N=2 (VEIN)  GL FG GOOD GL FG GOOD  30515- AVG  REA GGLD N=3  GL FG GOOO  30515/00101 REA GOLD (MASS. SULPH. HORZ.)  GL FG POOR  30515/003D1 REA GOLD (BARITE HORZ.) 30516- 101 REXSPAR (G79SA-001)  GL 8R  GL FG POOR FAIR  30517- 001 ART 30517-001 Dl ART 30517- AVG ART N=2  GL FG FAIR GL FG GOOD  30518-001 30518-00101 30518-002 3051B-AVG1  LUCKY LUCKY LUCKY LUCKY  GL FG FAIR  30518- AVG  LUCKY COON N=3  30519- 001 30519-00101 30519-501 30519-AVG1 30519-AVG 30521-001  TUIN TWIN TUIN TWIN TUIN JUNE  COON COON COON COON  GL FG GO/FR  (PIT 1) N=2  MOUNTAIN MOUNTAIN MOUNTAIN MOUNTAIN MOUNTAIN KAJUN  (FALC3.SAMPLE) (FALCB.SAMPLE) (G79TM-001 ) (FALCB.SAMPLE N=2  30521-00101 JUNE KAJUN 30521- 001D2 JUNE KAJUN 30521 -AVG JUNE KAJUN N=3 30521/101 JUNE KAJUN (G79JU-0C1)  GL FG GOOD GL FG FAIR GL FG GD/FR GL FG GD/FR GL FG FAIR GL FG FAIR GL BR FAIR GL FG FAIR CL FAIR GL FG GOOD GL FG FAIR GL FG FAIR GL FG FR/GD GL ER  FAIR  30522- 001 9C (ZN 1) 30522-001D3 BC (ZN 1)  GL FG FAIR GL FG FAIR  30522- AVG BC (ZN 1)N=2 30522/00101 3C (ZN 1) 30522/001D2 BC (ZN 1)  GL FG FAIR GL FG FAIR GL FG POOR GL BR FAIR  30523- 501  KING TUT (G79LU-001)  30524- 501 30525- 001 30525-002 30525-002D1 30525-AVG2  ELSIE (G79LU-002) M050UIT0 KING MOSOUITO KING (VEIN) MOSQUITO KING (VEIN) MOSQUITO KING N=2 (VEIN)  GL BR FAIR GL FG GOOD GL FG GOOD GL FG GOOO GL FG GOOD  30525- AVG  MOSQUITO KING N=2  GL FG GOOO  30526- 501  PET (G79PE-001)  30527- 001 30527-00101 30527-002 30527- AVG1 30528- 001 30528/00101 30531-001 30531-002 30531-00201 30531-AVG2  SPAR SPAR SPAR (FLUORINE SHOWING) SPAR N=2 WHITE ROCK WHITE ROCK RED TOP RED TOP (TRENCH) REO TOP (TRENCH) RED TOP N=2 (TRENCH)  GL BR FAIR GL FG GOOD GL FG GOOD  30531- AVG  REO TOP N=2  30532-001 FLUKE 30532-00101 FLUKE 30532- AVG FLUKE N=2 30533- 001  OR ELL 1D (RED MINERAL)  GL GL GL GL GL GL GL GL GL  FG FG FG FG FG FG FG FG FG  GL GL GL GL  FG FG FG FG  Pb6/A *6/4  Pb7/4 *.7:4  PbB/4 JIB/4  1B.862 0.02 15.6B8 0.01 3B.742 18.893 0.03 15.706 0.03 38.823 18.857 0.02 15.684 0.01 3B.715 18.869 0.03 15.699 0.03 38.755 18.804 0.24 15.661 0.24 38.904 18.776 0.50 15.702 0.50 38.708 19.177 0.10 15.911 0.20 3B.9B6 19.079 0.10 15.750 O.OB 39.185 19.040 0.D1 15.724 0.01 39.109 19.060 0.05 15.737 0.04 39.147 19.123 0.04 15.688 0.01 38.847 36.896 19.140 0.01 15.699 0.01 38.958 19.163 0.10 15.696 0.01 3B.872 19.132 0.03 15.694 0.01 3B.900 19.142 0.07 15.694 0.01 38.B37 19.013 0.05 15.704 0.02 3B.B13 19.012 0.04 15.691 0.04 38.846 19.057 0.07 15.716 0.18 36.825 19.013 0.05 15.69B 0.03 38.836 19.035 0.06 15.707 0.10 39.525 19.472 0.02 15.724 0.02 39.513 19.469 0.05 15.725 0.02 39.473 19.442 0.07 15.707 0.07 39.504 13.461 0.05 15.719 Q.04 39.396 19.441 0.04 15.575 0.14 38.309 18.294 0.01 15.552 0.01 38.337 18.232 0.06 15.554 0.06 3B.331 18.2B8 0.03 15.553 0.03 36.412 18.403 0.02 15.578 Q.02 38.243 18.245 0.30 15.516 0.30 38.B35 19.095 O.DB 15.6BB 0.1B 38.97 5 19.142 0.08 15.700 0.1B 38.335 19.075 0.01 15.692 0.01 38.827 19.071 0.02 15.692 0.02 38.877 19.124 0.02 15.694 0.02 3B.852 19.098 0.02 15.693 0.02 38.846 19.090 0.02 15.693 0.02 38.980 19.126 0.06 15.732 0.15 38.902 19.133 0.01 15.692 0.01 38.859 19.126 0.04 15.687 0.04 3B.B64 19.150 0.28 15.671 0.28 38.881 19.130 0.03 15.690 0.03 39.048 19.151 0.04 15.722 0.04 39.198 19.227 0.64 15.801 0.62 19.142 0.05 15.719 0.02 38.938 19.159 0.09 15.737 0.09 38.974 19.136 0.07 15.710 0.00 3B.905 19.148 0.08 15.724 0.04 3B.940  POOR GOOD GOOD POOR FAIR GOOO FAIR GD/FR GD/FR 19.146 0.06 15.721 0.04 38.939 GOOD 19.219 0.02 15.702 0.02 39.366 GOOD 19.227 0.05 15.704 0.05 39.356 GOOD 19.223 0.03 15.703 0.03 39.361 GOOD 19.362 0.02 15.715 0.02 39.401  Pb6/7  JB/7  Pb6/B  %6/B  0.03 0.03 0.02 0.03 0.24 0.50 0.20 0.11 0.01 0.06 0.05 0.03 0.10 0.04 0.07 0.06 0.05 0.05 0.06 0.06 0.02 0.05 0.07 0.05 0.00 0.01 0.07 0.04 0.03 0.30 0.16 0.09 0.02 0.03 0.03 0.03 0.03 0.11 0.06 0.04 0.2B 0.05 0.04 0.65  1.20232 1.20292 1.20232 1.20192 1.20066 1.19577 1.20528 1.21132 1.21088 1.21110 1.21B97 1.21924 1 .22084 1.21911 1.21968 1.21066 1 .21166 1.21260 1.21116 1.211B8 1.23B37 1 .23B09 1.237B2 1.23309 1.24019 1.17631 1.17539 1 .17S85 1.18137 1.17594 1.21718 1.21925 1.21552 1.21532 1.21B54 1 .21693 1.2164B 1.21575 1.21928 1.21926 1.22197 1.21927 1.21810 1.21684  0.02 0.01 0.02 0.03 0.03 0.04 0.00 0.06 0.01 0.03 0.04 0.00 0.10 0.04 0.06 0.04 0.01 0.00 0.03 0.03 0.01 0.04 0.01 0.02 0.00 0.00 0.02 0.01 0.00 0.02 0.00 0.00 0.02 0.01 0.02 0.02 0.02 0.00 0.01 0.01 0.05 0.01 0.01 0.14  0.4B6872 0.486640 0.487086 0.486879 0.483341 0.485070 0.492734 0.486886 0.486848 0.486B67 0.492258 0.492096 0.491874 0.492177 0.492076 0.489554 0.489B43 0.491415 0.489699 0.490557 0.492647 0.49271B 0.492534 0.492633 0.494320 0.477523 0.476B89 0.477206 0.479100 0.477093 0.492547 0.491974 0.491163 0.491186 0.491907 0.491547 0.491419 0.491512 0.491821 0.492191 0.492745 0.492006 0.490461 0.490511  0.03 0.01 0.03 0.03 0.01 0.05 0.00 0.04 0.00 0.02 0.03 0.02 0.03 0.03 0.03 0.02 0.01 0.00 0.02 0.02 0.01 0.03 0.01 0.01 0.00 0.01 0.03 0.02 0.01 0.02 0.00 0.00 0.01 0.02 0.01 0.02 0.02 0.00 0.06 0.01 0.03 0.03 0.01 0.15  0.06 0.10 0.07 O.OB  1.217B1 1.21748 1.21808 1.2177B  0.04 0.01 0.01 0.01  0.491608 0.491598 0.491880 0.491739  0.04 0.04 0.01 0.03  0.07 0.06 0.05 0.05 0.04  1.21779 1.22398 1.22433 1.22416 1.23213  0.03 0.01 0.01 0.01 0.01  0.491695 0.488203 0.48B550 0.48B377 0.491419  0.03 0.06 0.02 0.04 0.04  1  Adams P l a t e a u :  Sample  No  Deposit/Sample  Lead  Isotope  Name  5 2  Data  Mt A n l  Dual  Pb6/4  J6/4  Pb7/4  *7:4  Pb8/4  *8/4  Pb6/7  5S6/7  Pb6/8  *6/8  30533-00101  OR ELL  1D (RED MINERAL)  GL FG  FAIR  1 9 . 3 2 7 0.07  15.682  0.07 39.318 0.07  1 . 2 3 2 4 5 0.01  0.491567  0.01  30533-002  ORELL 1E (RED MINERAL)  GL FG  GOOD  1 9 . 3 5 S 0.02  15.705  0.02 39.377 0.03  1.23237  0.491516  0.02  3 0 5 3 3 - AVC  ORELL ID  GL FG  GD/FR  19.345 0.04  15.699  0.04 3 9 . 3 6 0 0 . 0 5  1.23229  0.01  0.491493  0.02  3 0 5 3 4 - 001  ORELL 2G (RED MINERAL)  GL F G  GOOO  19.121  15.705  0.02 39.044 0.03  1.21749  0.01  0.489721  0.01  30534-00101  ORELL 2G (RED MINERAL)  GL F G  GOOD  1 9 . 1 4 0 0.03  15.722  0.02 3 9 . 0 9 3 0 . 0 4  1.21744  0.02  0.489604  0.03  3 0 5 3 4 - AVG  ORELL 2G N=2  GL FG  GOOO  19.131  0.03  15.714  0.02 3 9 . 0 6 9 0 . 0 4  1.21747  0.02  0.489663  0.02  3 0 5 3 5 - 001  ORELL 3K (RED MINERAL)  GL F G  FAIR  19.354  0.05  15.706  0.03 3 9 . 3 8 3 0 . 0 5  1.23228  0.04  0.491420  0.02  3 0 5 3 6 - 001  ORELL 4N ( S I L V E R  GL FG  GOOD  19.081  0.04  15.708  0.04 38.899 0.04  1.21471 0.01  0.490516  0.01  3 0 5 3 7 - 001  ORELL SP  GL FG  GOOD  19.128  0.01  15.689  0.01 3 8 . 8 7 9 0.01  1.21923  0.01  0.4919B2  0.00  30537-001D1  ORELL  5P  GL FG  FAIR  19.128  0.05  15.694  0.05 3B.891  3 0 5 3 7 - AVG .  ORELL  5P N=2  GL FG  GD/FR  19.128  0.03  15.692  3 0 5 3 8 - 001  UTAH PROSPECT  (FORD)  GL FG  GOOD  ie.B93 0.02  15.704  0.03 3 8 . B B 5 0 . 0 3 0.02 3 8 . 6 9 9 0 . 0 2  GOOO  18.B64  1 8 . 8 7 5 0.01  0.07 38.696 38.659 15.691 0.01 38.651 15.695 0.03 38.676 15.698 0.03 38.932 15.680 0.05 39.001 15.715 0.04 38.967 15.698 0.05 39.235 15.820 0.00 38.BD6 15.681 0.07 3B.892 15.711 0.01 3B.B49 15.596 0.04 38.889 15.733 0.03 38.B02 15.7C3 0.13 38.846 15.723 0.08 39.080 15.714 0.02 39.251 15.E91 Q.06 38.977 15.631 0 . 0 5 38.979 15.635 0.06 38.97B 15.684 Q.06 39.375 15.741 6.04 39.297 15.717 0.03 39.336 15.729 0.04 39.172  N=3  (RED MINERAL)  (RED MINERAL)  KING,A)  0.02  UTAH PROSPECT  (FORD)  GL FG  3O53B-O01D2 UTAH PROSPECT  (FORD)  GL FG  GOOD  3 0 5 3 8 - 001D3 UTAH PROSPECT  (FCSD)  GL F G  GOOO  ie.8a0  GL FG  GOOD  18.863 0.03  GL FG  FAIR  IS.249  30538-001D1  0.03  30S3B-AVG  UTAH PROSPECT  3 0 5 3 9 - 001  MT McCLENNAN ( X - C U T T I M G  30539-002  MT McCLENNAN  GL FG  FAIR  19.288 0.04  3 0 5 3 9 - AVG  MT McCLENNAN  GL FG  FAIR  19.269 0.05  3 0 5 4 0 - 501  BIRCH ISLAND  GL GSC F A I R  19.335  3 0 5 4 1 - 001  SUNRISE  GL FG  FAIR  1 9 . 0 8 6 0.07  SUNRISE  GL FG  GOOD  19.123 0.03  30541-002  N=4  0.07  Mil'!)  N=2 (HL P45 K Q 7 3 - 3 6 )  0.05  0.00  3 0 5 4 1 - AUG  SUNRISE  GL FG  FR/GD 19.105 0.05  3 0 5 4 2 -001  VAVENEY  GL FG  GOOD  19.127  30542-00101  VAVENEY  GL  FAIR  19.055 0.14  3 0 5 4 2 - AVG  VAVEN9Y  N=2  GL FG  GD/FR  19.091  0.08  3 0 5 4 3 - 001  TINDALL  (ADIT  GL FG  GOOD  19.251  0.02  GL FG  FAIR  19.355  0.06  3 0 5 4 4 - 001  50NJA  N=2  DUMP)  r  G  0.03  3 0 5 4 5 - 001  SILVER K I N C - S I L V E  C  QUEEN  GL FG  GOOD  19.098 0.07  30545-00101  SILVER K I N G - S I L V E R  QUEEN  GL FC  FAIR  19.110 0.06  3 0 5 4 5 - AVG  5ILVER K I N G - S I L V E R  QUEEN N=2  GL FG  GD/FR  19.104  3 0 5 4 6 - 001  LEEMAC  GL FG  FAIR  19.406 0.04  GL FG  GOOD  19.375 0.03  GL FG  FR/GD 19.391  0.07  15.702  0.05  0.01  1.21881 0 . 0 2  0.491834  0.02  1.21902  0.02  0.491908  0.01  1.20308  0 . 0 0 0.488201  0.01  0.08  1.20267  0.01  0.03  0.488007  0.02  1.20287  0.01  0.438240  0.01  0.05  1.20292  0.01  0.488468  0.05  0.04  1 . 2 0 2 B 9 0.01  0.488229  0.03  0.06  1.22757  0.02  0.494426  0.03  0.06  1.22736  0.01  0.494536  0.05  0.06  1.22747  0.02  0.494481  0.04  0.00  1.22200  0.00  0.493642  0.00  0.08  1 .21715 0 . 0 3  0.491827  0.03  0.04  1.21717  0.03  0.491691  0.02  0.06  1.21716  0.03  0.491759  0.03  0.03  1 .21804  0.01  0.491833  0.01  0.16  1.21344  0.05 0.491074  0.08  0.09  1.21574  0.03  0.491454  0.05  0.05  1.22509  0.01  0.492605  0.02  0.06  1 .23353 0 . 0 0 0.493132  0.01  0.08  1.21789  0.05 0.489971  0.02  0.06  1.21826  0.01  0.490261  0.02  0.07  1.21BC7 0 . 0 3  0.490116  0.02  0.04  1.23287  0.02  0.492849  0.01  0.04  1.23271 0.01  0.493036  0.01  0.04  1.23279  0.02  0.492943  0.01  0.03  1.22329  0.01  0.491845  0.03 0.00  30546-00101  LEEMAC  3 0 5 4 6 - AVG  LEEMAC  3 0 5 4 7 - 001  ROUGE  GL FG  GOOD  1 9 . 2 6 7 0.01  0.491910  ROUGE  GL FG  GOOD  1 9 . 2 5 3 O.QO 1 5 . 7 3 8  1.22330  0.01  0.491878  0.02  3 0 5 4 7 - AyG  ROUGE  N=2  GL FG  GOOD  1 9 . 2 6 0 0.01  1 .21977 0 . 0 0  0.492194  0.00  3 0 5 4 8 - 001  PS-3S-17S  GL FG  GOOD  19.180 0.00  0.00 3 9 . 1 3 9 0 . 0 0 0.00 3 9 . 1 5 6 0 . 0 2 15.744 0.00 38.696 0.00 1 5.72 5 0 . 0 0 38.955 0.00  1.22331 0 . 0 0  30547-001D1  30548-0101  PS-35-175  GL FG  GOOD  19.174  15.717  0.00  30548-AVG  PS-8S-175  GL FG  GOOD  19.177 0.00  1.21997 0 . 0 0 0.492212 0.00 3 8 . 9 6 2 0 . 0 0 ' 1 .21937 0 . 0 0 0 . 4 9 2 2 0 3 0.00  N=2  N=2  0.04  0.00  15.750  15.721  0.00  

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