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Structural geology of part of the Crooked Lake area, Quesnel Highlands, British Columbia Carye, Jeffrey Alyn 1986

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STRUCTURAL GEOLOGY OF PART OF THE CROOKED LAKE AREA, QUESNEL HIGHLANDS. BRITISH COLUMBIA By JEFFREY ALYN CARYE B.Sc,  McGill University,  1977  A THESIS SUBMITTED I N PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  in THE DEPARTMENT OF GEOLOGICAL SCIENCES  We a c c e p t t h i s t h e s i s as c o n f o r m i n g to the required  standard  THE UNIVERSITY OF BRITISH COLUMBIA March 1986 9 Copyright  1986  In presenting  this thesis in partial fulfilment  of the  requirements  for  an advanced  degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department  or  by  his  or  her  representatives.  It  is  understood  that  copying  or  publication of this thesis for financial gain shall not be allowed without my written permission.  Department The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3  DE-6(3/81)  1  Structural Geology of Part of the Crooked Late Area. Quesnel Highlands. British Coluwbia ABSTRACT The Crooked Lake area, which l i e s a t t h e boundary o f t h e Omineca C r y s t a l l i n e B e l t and t h e Intermontane B e l t o f t h e Canadian C o r d i l l e r a , has been examined w i t h close  attention  being p a i d t o  the  detailed  structural  relations  of  the  five  l i t h o l o g i e s t h a t comprise t h i s map area - t h e l a t e P r o t e r o z o i c Snowshoe Formation, t h e l a t e Paleozoic A n t l e r Formation, Upper T r i a s s i c t o Lower J u r a s s i c p h y l l i t e s and p h y l l i t i c s i l t s t o n e s and a u n i t o f micaceous q u a r t z i t e , Lake P h y l l i t e and t h e Eureka Q u a r t z i t e , Lower J u r a s s i c Takla Group. with  respect  to  each o t h e r ,  respectively,  h e r e i n named t h e Crooked and t h e Upper T r i a s s i o t o  These u n i t s f o r m a normal s t r a t i g r a p h i c though g i v e n data suggests f a r  i n t e r n a l r e l a t i o n s f o r each o f t h e f i v e u n i t s .  more  succession complicated  The major c o n t a c t s , where exposed,  were seen t o be continuous w i t h i n t e r n a l f o l i a t i o n f a b r i c s ,  sharply planar  somewhat g r a d a t i o n a l i n t h e case o f t h e T a k l a base), and o c c a s i o n a l l y  (to  associated  w i t h m y l o n i t i c f a b r i c s . These s u r f a c e s may r e p r e s e n t f a u l t s , though s u f f i c i e n t data i s not a v a i l a b l e f o r e s t i m a t e s o f displacement magnitude and/or d i r e c t i o n t o be given. S t r u c t u r a l f e a t u r e s used t o develop a r e l a t i v e t i m i n g sequence f o r i n t e r n a l p r o g r e s s i v e d e f o r m a t i o n o f t h e Crooked Lake rock u n i t s i n c l u d e bedding s u r f a c e s and c o m p o s i t i o n a l l a y e r i n g s , f o l i a t i o n s and cleavages, c r e n u l a t i o n s and o t h e r structures,  minor f o l d forms and f o l d i n t e r f e r e n c e p a t t e r n s ,  linear  and f r a c t u r e s e t s .  The f i v e d i s t i n c t s e t s o f d e f o r m a t i o n f e a t u r e s t h a t r e p r e s e n t t h i s t i m i n g sequence are  the  following:  isoclinal,  intrafolial,  rootless  folds  of  compositional  l a y e r i n g found e x c l u s i v e l y i n t h e Snowshoe and A n t l e r Formations (D1), tight  folds  of  bedding,  compositional layering,  c o n t a c t s and a p e r v a s i v e mica/amphibole f o l i a t i o n  ii  earlier  foliations,  open t o and major  (D2 r e l a t i v e t o Snowshoe and  Structural Beoloqy of Part of the Crooked Lake Area. Quesnel Highlands. British Colunhia A n t l e r ) , u p r i g h t open t o medium f o l d s o f e a r l i e r s u r f a c e s and major c o n t a c t s ( 0 3 ) , g e n t l e t o open f o l d s and k i n k f o l d s o f p e r v a s i v e D2 f o l i a t i o n and c o m p o s i t i o n a l l a y e r i n g (D4), and n o r t h e a s t e r l y d i r e c t e d f a u l t s and f r a c t u r e s e t s (D5). The metamorphic h i s t o r y o f t h e Crooked Lake rock u n i t s has been deduced f r o m extensive  microscopic  examination  of  textures  B a r r o v i a n - t y p e metamorphism accompanied t h e f i r s t the f i r s t  and  mineral  assemblages.  t h r e e d e f o r m a t i o n a l episodes;  event may have reached a m p h i b o l i t e grade, t h e second episode reached  temperatures o f 500-575° a t pressures o f 4-7 kbars ( f r o m e q u i l i b r i a o f p e l i t i c and m a f i c assemblages), and t h e t h i r d approached o n l y t h e lower t o middle g r e e n s c h i s t grade. Appendices have been i n c l u d e d summarizing rock d e s c r i p t i o n data,  structural  d a t a , f o l d f o r m d a t a , and s t e r e o - p h o t o g r a p h y o f prominent s t r u c t u r a l f e a t u r e s .  iii  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Columbia TABLE OF CONTENTS PAGE ABSTRACT  ii  FIGURES  vi  TABLES  xiv  PLATES  xv  MINERAL ABBREVIATIONS  xvii  ACKNOWLEDGEMENTS I  II  xix  INTRODUCTION L o c a t i o n and Access  1  Physiography and G l a c i a t i o n  1  P r e v i o u s and C u r r e n t Work  4  GENERAL GEOLOGY Regional Geology  7  L o c a l Geology III  IV  11  STRATIGRAPHY Introduction  13  Kaza Group - Snowshoe Formation  16  S l i d e Mountain Group - A n t l e r Formation  21  Eureka Q u a r t z i t e  27  Crooked Lake P h y l l i t e  28  Takla Group  33  STRUCTURE Introduction  37  Maps and Cross .Sections  40  Domains  41  Phase One  44  Phase Two  48  Phase Three  57  Phase Four  67  L a t e B r i t t l e Phase  67  iv  Structural Geology of Part of the Crooked Lake area. Quesnel Highlands. British Coluitbia S t r u c t u r a l Summary  V  69  METAMORPHISM Introduction  74  Q u a r t z o - F e l d s p a t h i c Type  79  P e l i t i c Type  83  Basic Type  92  Calcareous Type  96  U l t r a b a s i c Type  99  Metamorphism and Deformation  99  VII  CONCLUSION  104  VIII  LIST OF REFERENCES CITED  107  VIII  APPENDICES A - Rock D e s c r i p t i o n s  112  B - S t r u c t u r a l F i e l d Data  154  C - T-Alpha P l o t s o f F o l d Form Data  172  D - P l a t e s 5 ( a - l ) - Stereophotos  179  v  Structural Geology of Part of the Crooked Lake Area, quesnel Highlands, British Colunbia FIGURES FIGURE 1.  PAGE L o c a t i o n of  t h e Crooked Lake Map Area i n  east-central  B r i t i s h Columbia 2.  2  D e t a i l e d l o c a t i o n and a r e a l e x t e n t o f t h e map area a t Crooked Lake ( s t u d y areas of o t h e r M a s t e r s ' s t u d e n t s a l s o shown) . .  3.  3  D i r e c t i o n o f i c e movement o f F r a s e r I c e Sheet and l a t e i c e re-advances i n C e n t r a l B r i t i s h Columbia ( f r o m T i p p e r 1971, p. 39)  4.  Glacial  4  v a l l e y s t y p i c a l o f t h e n o r t h e a s t e r n slopes o f  Eureka S y n c l i n e 5.  Tectonic  5  subdivisions  o f t h e Canadian C o r d i l l e r a showing  present study area (adapted f r o m T e c t o n i c Assemblage Map o f t h e Canadian C o r d i l l e r a ; T i p p e r e t a l . 1981) 6.  8  The Okanagan P l u t o n i c and Metamorphic Complex: major s t r u c t u r a l components and t h e Quesnel - N o r t h America s u t u r e zone. ( F i g u r e 4 o f O k u l i t c h 1984, p. 1181)  7.  10  Contacts o f t h e Crooked Lake rock u n i t s a.  Panorama o f t h e southwest s i d e o f Eureka S y n c l i n e ; upper and lower  ,  c o n t a c t s o f A n t l e r are shown as  mapped. Crooked Lake P h y l l i t e / T a k l a c o n t a c t zone i s assumed f r o m K . V . Campbell (1971) {DIR-045} b.  14  Southwestern Crooked Lake P h y l l i t e / T a k l a c o n t a c t zone as mapped {DIR-045}  c.  15  Mapped c o n t a c t s between Crooked Lake P h y l l i t e and Takla i n  the  n o r t h e a s t e r n c o n t a c t zone ; note p o s s i b l e p h y l l i t e i n f o l d a t t o p r i g h t r e F i g u r e 16d {DIR-318} 8.  Interlayered typical  p l a g - b i o - q t z s c h i s t and m u s c - q u a r t z i t e  o f t h e Snowshoe Formation i n t h e Crooked Lake  area <DIR-350,LOC-RZ10} 9.  15  17  Snowshoe/Antler c o n t a c t a.  Sharply d e f i n e d c o n t a c t between Snowshoe Formation (below) and A n t l e r Formation (above)  {DIR-030,L0C-J112}  vi  19  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia FIGURE b.  PAGE Snowshoe s l i v e r w i t h i n A n t l e r plag-hnbd s c h i s t schist;  and c h l - h n b d  s l i v e r i s p a r t o f a D2 f o l d form i n v o l v i n g t h e c o n t a c t  between t h e two u n i t s ; s i m i l a r f e a t u r e i s shown i n F i g u r e 12 {DIR-020,L0C-J114} 10.  19  N e a r l y continuous 150 meter s e c t i o n o f t h e A n t l e r Formation bounded t o p and bottom by exposed c o n t a c t s (shown) {DIR-320}  22  11.  Summary o f t h e p r i n c i p l e A n t l e r l i t h o l o g i e s  23  12.  Interfingering (dark u n i t )  of Antler  qtz-plag-chl-hnbd  w i t h Eureka Q u a r t z i t e ( l i g h t  schist  u n i t ) {DIR-055,  L0C-J101} 13.  26  Micaceous q u a r t z i t e w i t h p e r v a s i v e and f o l d e d q u a r t z v e i n i n g i s  platy  t e x t u r e ; boudined  a common f e a t u r e i n t h i s  u n i t {DIR-062, LOG-J94} 14.  28  Black p h y l l i t e  and grey p h y l l i t i c  characteristic  s t r o n g f o l i a t i o n and d i s c o n t i n u o u s ,  transposed l a y e r i n g ;  siltstone  with  note t i g h t 02 f o l d a t upper r i g h t h a n d  corner {DIR-020, L0C-J88}  29  15.  Summary o f t h e p r i n c i p l e Crooked Lake P h y l l i t e l i t h o l o g i e s  30  16.  D i s t i n c t i v e l i t h o l o g i e s o f t h e T a k l a Group r o c k s a.  Foliated chl-hnbd-plag Meta-diorite of  with  lensoid/spheroids  p l a g - c h l - e p d i r e c t e d along t h e main f o l i a t i o n (S2) {DIR-100,  L0C-J59} b.  Matrix-supported  34 b r e c c i a w i t h d i o r i t e and massive hornblende  c l a s t s elongate i n t h e d i r e c t i o n o f  t h e main f o l i a t i o n (S2) {DIR-090,  L0C-J60} c.  Clast-supported  34 conglomerate w i t h d i o r i t e  c l a s t s t h a t show a  weak e l o n g a t i o n i n t h e plane o f t h e main f o l i a t i o n (S2) {DIR-335, L0C-J144} d.  35  Folded c o n t a c t (shown) between v o l c a n i c a r e n i t e and p h y l l i t e ; t h i s p h y l l i t e , more t y p i c a l o f  t h e Crooked Lake P h y l l i t e , i s  f u l l y c o n t a i n e d w i t h i n t h e T a k l a Group r o c k s { D I R - 318, L0C-J163} . . . 17.  V a r i a t i o n o f minor f o l d forms and t h e i r o r i e n t a t i o n s across t h e Crooked Lake a r e a ;  Domains I and I I are separated by t h e  vii  35  Structural Seology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia FIGURE  PAGE Boss tttn. A n t i c l i n e ; major c o n t a c t s shown as heavy dashed lines  18a.  39  Contour p l o t s o f p o l e s t o S2 f o l i a t i o n s f r o m Domains I & I I ( c o n t o u r s r e p r e s e n t 0 , 5 , 1 0 , 1 5 , 2 0 . o f p o i n t s per 1 * s t e r e b n e t area)  18b.  42  Contour p l o t s o f 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 (bedding?) and envelopping s u r f a c e s o f D2 f o l d s ( c o n t o u r s are 0 , 5 , 1 0 * per 1% area)  19.  43  Q t z - p l a g - e p s u b u n i t s i n c h l - q t z - h n b d s c h i s t show t i g h t l y f o l d e d and r e f o l d e d forms ( o u t l i n e d ) {DIR-345, L0C-RZ6}  20.  45  I s o c l i n a l f o l d closure i n v o l v i n g compositional l a y e r i n g o f qtz-musc marble and p l a g - m u s c - b i o - q t z s c h i s t {DIR-330, L0C-J74}  21.  45  C h a r a c t e r i s t i c s o f D1 minor f o l d forms a.  Equal-area net p l o t o f p o l e s t o a x i a l s u r f a c e s o f D1 f o l d s f r o m both Domains  b.  Equal-area net p l o t o f D1 f o l d hinges f r o m both Domains  c.  t - a l p h a p l o t o f 01 F o l d Forms Snowshoe J72, J74, J74b, A n t l e r RZ6 (see Appendix C f o r e x p l a n a t i o n o f f o l d form curves)  22.  Equal area net p l o t o f p o l e s t o p l a n a r measurements f r o m a s i n g l e S2 f o l i a t i o n s u r f a c e a t RZ11 i n t h e Snowshoe; t h i s v a r i a b i l i t y i s c h a r a c t e r i s t i c o f S2 f o l i a t i o n s u r f a c e s across t h e area  23a.  49  U p r i g h t open t o medium f o l d s i n i n t e r l a y e r e d p h y l l i t e - p h y l l i t i c s i l t s t o n e ; t h e s i g m o i d a l shape o f segments o f s i l t s t o n e u n i t between cleavage planes i n d i c a t e shear along those planes; u n i t s d r a s t i o a l l y t h i n toward l e f t {DIR-340, LOC-J40}  23b.  50  U p r i g h t t i g h t s i m i l a r f o l d t r u n c a t e d on t h e r i g h t a g a i n s t p l a n a r f o l i a t e d p h y l l i t e {DIR-350, LOC-J36}  24.  t - a l p h a p l o t s o f D2 f o l d s a.  Open f o l d s a t J40, J89, J57, RZ8 ( c u r v e s e x p l a i n e d i n Appendix C)  b.  Medium f o l d s a t J 4 1 , J5, RZ5, RZ6, RZ7, RZ10  viii  50  Structural Geology of Part of the Crooked Late Area. Quesnel Highlands. British Coluwoia FIGURE c.  T i g h t f o l d s f r o m J26, J117, J36, J26b, J41b  d.  B a s s e t t / S t a r k p a i r t a k e n f r o m P l a t e 3, Cross S e c t i o n 1  25.  02 f o l d elements f r o m Domains I & I I shown as contour p l o t s a.  Poles t o S2 a x i a l planes o f minor f o l d forms f r o m Domain I (0 8. 10* per 1% area c o n t o u r s shown)  b.  Poles t o S2 a x i a l planes o f minor f o l d forms f r o m Domain I I (0,10,20,30% per 1% area c o n t o u r s shown)  c.  L2 f o l d hinges f r o m Domain I ( 0 , 5 , 1 0 , 1 5 , * per 1 * area c o n t o u r s shown)  d.  L2 f o l d hinges f r o m Domain I I ( 0 , 1 0 , 2 0 , 3 0 * per 1 * area c o n t o u r s shown)  26a.  Recumbant open f o l d s i n p h y l l i t i c s i l t s t o n e {DIR-295, L0C-J89}  26b.  Recumbant t i g h t f o l d s i n p h y l l i t i c s i l t s t o n e ; note curved f o l d hinges ( ' s h e a t h - l i k e ' f o l d f o r m ) {DIR-345,L0C-J171}  27.  Interference  ...  o f recumbant t i g h t phase two f o l d s w i t h u p r i g h t  phase t h r e e f o l d s ( t o l e f t near q u a r t z v e i n ) {DIR-317, L0C-J117} 28.  U p r i g h t open D3 f o l d i n g of A n t l e r / E u r e k a c o n t a c t {DIR-325, L0C-J102}  29.  D3 cleavages and c r e n u l a t i o n s f r o m Domains I & I I shown as contour p l o t a.  Poles t o S3 cleavages f r o m Domain I (0 & 10* per 1 * area c o n t o u r s shown)  b.  Poles t o S3 cleavages f r o m Domain I I ( 0 , 5 , 1 0 , 1 5 * per 1 * area c o n t o u r s shown)  c.  L3 c r e n u l a t i o n l i n e a t i o n s f r o m Domain I ( 0 , 5 , 1 0 * per 1 * area c o n t o u r s shown)  d.  L3 c r e n u l a t i o n l i n e a t i o n s f r o m Domain I I ( 0 , 1 0 , 2 0 , 3 0 , 4 0 * per 1 * area c o n t o u r s shown)  30.  C h a r a c t e r i s t i c s of D3 minor f o l d forms a.  Equal area net p l o t o f p o l e s t o a x i a l planes o f D3 f o l d forms from Domain I I ( 0 , 5 , 1 0 * per 1 * area c o n t o u r s shown)  b.  Equal area net p l o t o f f o l d hinges t o D3 f o l d forms f r o m Domain I I ( 0 , 5 , 1 0 , 1 5 , 2 0 * per 1 * area c o n t o u r s shown) o  ix  Structural fieologw of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia FIGURE c.  PAGE t - a l p h a p l o t o f D3 F o l d Forms C. L. P h y l l i t e J98, J104, J117 (curves e x p l a i n e d i n Appendix C)  31a.  60  Combined data p l o t ( e q u a l a r e a ) t o show t y p i c a l spread o f poles t o S2 f o l i a t i o n and a x i a l planes and L2 f o l d hinges i n r e l a t i o n t o 04 f e a t u r e s f r o m Domain I (D1 f e a t u r e s included)  31b.  61  Combined data p l o t ( e q u a l a r e a ) showing r e l a t i o n s h i p between D2 and D3 f e a t u r e s i n Domain I I along upper and lower A n t l e r contacts (J85—>J114)  31c.  62  Combined data p l o t ( e q u a l a r e a ) showing r e l a t i o n s h i p between 02 and D3 f e a t u r e s i n Domain I I i n t h e n o r t h e a s t e r n - m o s t p a r t of t h e map area ( J 1 4 2 — > J 1 7 1 )  32a.  ,.  63  Double k i n k o f main f o l i a t i o n (S2) i n Crooked Lake P h y l l i t e ; note change w i t h depth t o very open f o l d i n g {DIR-060, LOC-J77}  32b.  64  Clockwise k i n k i n Crooked Lake P h y l l i t e ; zone i s 3-4 cm wide and grades i n t o very open f o l d i n g below {DIR-005, L0C-J84}  33.  64  D4 f o l d elements f r o m Domains I & I I shown as contour p l o t s a.  Poles t o S4 a x i a l planes o f minor f o l d forms f r o m Domain I (0,10,20% per 1% area c o n t o u r s shown)  b.  S4 k i n k band boundry planes f r o m Domain I I (0 & 50% per 1% area c o n t o u r s shown)  c.  L4 f o l d hinges f r o m Domain I (0 & 10% per 1$ area c o n t o u r s shown)  d.  L4 k i n k axes f r o m Domain I I (0 & 30% per 1% area c o n t o u r s shown)  34.  65  S t r e s s d e t e r m i n a t i o n o f D4 episode from deformed S2 f o l i a t i o n s ( f r o m C a r t e r & R a l e i g h , 1969)  35.  66  Contour p l o t s o f p o l e s t o f r a c t u r e s f r o m Domains I & I I ( c o n t o u r s r e p r e s e n t 0,5,10% o f p t s per 1% s t e r e o n e t area  36.  Schematic s t r u c t u r a l summary. a.  A n t l e r Formation i s emplaced on t o p o f t h e Snowshoe Formation w i t h a t t e n d a n t D1 f o l d i n g .  b.  The upper t h r e e u n i t s are emplaced atop t h e lower two  x  68  Structural Geology of Part of the Crooked Late Area. Quesnel Highlands. British Colunbia FIGURE  PAGE presumably a t a h i g h e r l e v e l o f t h e c r u s t (no a s s o c i a t e d d e f o r m a t i o n ) ; t h r u s t s p l i c i n g may account f o r t h e p i n c h i n g out o f t h e Eureka Q u a r t z i t e .  c.  E a r l y stage o f D2 d e f o r m a t i o n develops p a r a l l e l f o l d s .  d.  As temperatures and degree o f d e f o r m a t i o n i n c r e a s e s ,  parallel  f o l d i n g g i v e s way t o s i m i l a r f o l d i n g , and c o n s i d e r a b l e l i m b t h i n n i n g of u n i t s . e. 37.  D3 f o l d i n g produces present day p a t t e r n  70  Pressure and temperature ranges f o r metamorphism and f a c i e s s u b d i v i s i o n o f t h e ' P - T ' f i e l d (adapted f r o m Turner  38a.  [1981] p. 420)  75  B i o t i t e - q u a r t z s c h i s t w i t h minor muscovite and p o r p h y r o b l a s t o f g a r n e t ; micas and ' c r y p t o c r y s t a l l i n e ' banding ( f e l s i c s ? ) d e f i n e S2 f o l i a t i o n ( c r o s s - n i c o l s i n s e r t e d , X12.5, L0C-RZ10)  38b.  80  M u s c o v i t e - b i o t i t e - q u a r t z s c h i s t w i t h garnet and K-f eldspar p o r p h y r o b l a s t s ; K-spar i s a l i g n e d w i t h S2 f o l i a t i o n d e f i n e d by micas ( c r o s s - n i c o l s i n s e r t e d , X12.5, L0C-RZ10)  39.  80  B i o t i t e q u a r t z i t e o f Eureka Q u a r t z i t e w i t h magnetite v e i n i n g and unusual hornblende c r y s t a l s ; t h e b i o t i t e here i s green; o r d i n a r i l y i t i s brown and muscovite i s t h e more common mica (Plane p o l a r i z e d l i g h t , X12.5,L0C-J104)  40.  82  P e l i t i c s c h i s t f r o m Snowshoe Fm.; an e a r l i e r f o l i a t i o n S1 has been d i s r u p t e d by t h e S2 f o l i a t i o n ; numerous ' h i g h a n g l e ' b i o t i t e s are common ( t o p o f p h o t o ) and are crossed by S2 rnuscovites ( c r o s s - n i c o l s , X12.5, L0C-RZ10)  41.  84  Open f o l d i n g i n Crooked Lake P h y l l i t e (a s l a t y s u b l i t h o l o g y ) ; note dark l a y e r s have l a r g e amount of g r a p h i t e t h a t has been i n j e c t e d up i n t o S2 oleavage planes ( p r o b a b l y w h i l e u n i t was s t i l l u n c o n s o l i d a t e d and wet) ( c r o s s - n i c o l s , X12.5, L0C-J7)  85  42a.  C t d - g n - p l a g - q t z - m u s c p o r p h y r o b l a s t i c p h y l l i t e (DIR-005, L0C-J85) . . .  87  42b.  M i c r o s c o p i c f a b r i c o f p o r p h y r o b l a s t i c p h y l l i t e showing p l a g and i l m p o r p h y r o b l a s t s i n m a t r i x of m u s c o v i t e / s e r i c i t e g r a p h i t e - q u a r t z ; S2 f o l i a t i o n t y p i c a l l y warped around  xi  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia FIGURE  PAGE p o r p h y r o b l a s t s ; S i i n p l a g = Se o f f o l i a t i o n ( c r o s s - n i c o l s i n s e r t e d , X12.5, L0C-J85)  43a.  87  P o r p h y r o b l a s t i c p h y l l i t e w i t h p l a g , c t d , c h l , and i l m i n c o n t a c t ; c h l occurs i n c e n t e r o f c t d c r y s t a l ( d a r k ) , t h e corroded f o r m of which c o n t r a s t s w i t h u n i t s where c t d occurs w i t h no p l a g ( p l a n e p o l a r i z e d l i g h t , X12.5, L0C-J85)  43b.  88  Same sample as above w i t h c r o s s - n i c o l s i n s e r t e d ; S2 f o l i a t i o n though d e f l e c t e d by p o r p h y r o b l a s t s i s continuous w i t h i n c l u s i o n s i n c r y s t a l s (X12.5, L0C-J85)  44a.  88  Garnet and i l m e n i t e w i t h i n p o r p h y r o b l a s t i c p h y l l i t e ; garnet shows r o t a t e d i n c l u s i o n s t h a t are c o n t i n o u s w i t h S2 f o l i a t i o n a t c r y s t a l boundries (plane p o l a r i z e d l i g h t ; X50, L0C-J85)  44b.  89  S t a u r o l i t e i n p o r p h y r o b l a s t i c p h y l l i t y e w i t h S i = Se; b i o t i t e c r y s t a l nearby i s t h e o n l y example of b i o t i t e i n Crooked Lake P h y l l i t e ( c r o s s - n i c o l s i n s e r t e d , X12.5, L0C-J47)  45.  C h l - h n b d - e p - q t z Meta-wacke; m a f i c m i n e r a l s d e f i n e t h e S2 foliation  i n these and o t h e r b a s i c u n i t s ( p l a n e p o l a r i z e d l i g h t ,  X12.5, L0C-RZ4) 46.  89  93  The d i s t r i b u t i o n of m a f i c assemblages f o r t h e A n t l e r Formation; s u r f a c e s shown separate assemblages on e i t h e r s i d e o f two r e a c t i o n s (hornblende i n and o l i g i o c l a s e i n ) discussed i n the t e x t  47.  95  Pressure temperature p l o t o f e q u i l i b r i a r e l e v a n t t o t h e Crooked Lake q u a r t z o - f e l d s p a t h i c , p e l i t i c , and m a f i c composition types  48.  97  Coarse and very f i n e banding t e x t u r e i n p e l i t i c marble o f Snowshoe t h a t o u t l i n e s S2 f o l i a t i o n ( c r o s s - n i c o l s , X12.5, L0C-RZ11)  49.  98  Summary o f m i n e r a l growth r e l a t i v e t o d e f o r m a t i o n f e a t u r e s composed from diagrams o f i n d i v i d u a l samples and t h i n s e c t i o n s d e s c r i b e d i n Appendix A  100  xii  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia FIGURE 50.  PAGE R e l a t i v e t i m i n g r e l a t i o n s between metamorphism and d e f o r m a t i o n and t e n t a t i v e c o r r e l a t i o n w i t h t h e a b s o l u t e t i m e s c a l e ; metamorphic s c a l e shows t h r e e g e n e r a l i z e d grades: b u r i a l , greenschist, amphibolite  xiii  102  Structural geology of Part of the Crooked Late Area, quesnel Highlands. British ColuitDia TABLES TABLE I  PAGE C h a r a c t e r i s t i c Features o f t h e F i v e Phases o f Deformation a t Crooked Lake  II-A  38  D i s t r i b u t i o n o f M i n e r a l Assemblages i n Domain I o f t h e Crooked Lake Area  II-B  76  D i s t r i b u t i o n o f M i n e r a l Assemblages i n Domain I I o f t h e Crooked Lake Area  77  xiv  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia PLATES PLATE  PAGE  1.  The Geology o f P a r t o f t h e Crooked Lake Area  2.  The S t r u c t u r e o f P a r t o f t h e Crooked Lake Area  3.  Two Cross S e c t i o n s  of Structure of  Part  of  .^iacfcrPeGket l  . . . ..Book Pooket  t h e Crooked  ^  Lake Area 4.  . . . Back Pocket.  Stereophotos of v a r i o u s f e a t u r e s a t Crooked Lake Chl-hnbd-plag  meta-diorite  with  v  r  interlayered/interfolded  q t z - c h l s c h i s t ( A n t l e r ) {DIR-325, L0C-RZ3} b.  M  0>\k^^  v n  Crooked Lake Area a.  ^  Back-Rocket-  Six S t r u c t u r a l / S t r a t i g r a p h i c Sections of Part of the  5.  f  179  Cross-fractured chl-hnbd-plag meta-diorite; fractures f i l l e d w i t h e p i d o t e , q u a r t z , and magnetite ( A n t l e r ) {DIR-335, L0C-RZ3}  c.  179  Qtz-chl-hnbd schist w i t h i n t e r layers of  qtz-plag-ep  meta-wacke t h a t show t i g h t t o i s o c l i n a l f o l d shapes ( A n t l e r ) {DIR-350, L0C-RZ6} d.  180  Red sandstone c o n t a i n e d w i t h i n p h y l l i t e i s open t o medium f o l d e d ; note cohesiveness o f sandstone (as opposed t o severe d i s r u p t i o n o f p h y l l i t e by S2 f o l i a t i o n ) (Crooked Lake P h y l l i t e ) {DIR-350, L0C-J52}  e.  Typical  contact  between A n t l e r  and Eureka Q u a r t z i t e ;  180  hnbd-plag  meta- d i o r i t e  note very open f o l d e d f o r m o f  c o n t a c t {DIR-315, LOC-J86} f.  181  Phase one i s o c l i n e o f c h l - h n b d s c h i s t and  qtz-plag-ep  meta-wacke ( A n t l e r ) {DIR-350, L0C-RZ6} g.  I n c l i n e d phase two medium f o l d s  in  182 musc-plag-qtz  s c h i s t (Snowshoe) {DIR-320, L0C-RZ8} h.  Upright  182  phase two medium ' c l o c k w i s e vergence' f o l d i n  chl-plag-hnbd s c h i s t ;  note p o s s i b l e t i g h t f o l d forms  i n v o l v e d i n upper hinge o f f o l d ( A n t l e r ) {DIR-335, L0C-RZ5} i.  U p r i g h t phase two medium t o t i g h t f o l d o f siltstone  in  p h y l l i t e matrix;  phyllitic  f o l d appears t o  xv  be r o o t l e s s  183  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia PLATE  PAGE (Crooked Lake P h y l l i t e ) {DIR-330, L0C-J33}  j.  Upright  phase t h r e e f o l d showing g r a d u a l change i n  183 form  f r o m open t o medium w i t h depth (Eureka Q u a r t z i t e ) {DIR-310,L0C-J98} k.  184  Recumbant t i g h t phase two f o l d r e f o l d e d by u p r i g h t  phase  t h r e e medium f o l d (Eureka Q u a r t z i t e ) {DIR-315,L0C-J104> 1.  185  U p r i g h t steep p l u n g i n g phase f o u r f o l d s i n Domain I t i g h t phase two f o l d s are p r e s e n t (near bottom l e f t i n photo) (Crooked Lake P h y l l i t e ) {DIR270, L0C-J33}  xvi  185  Structural Geology of Part of the Crooked Late Area. Quesnel Highlands. British Coltutbia MINERAL ABBREVIATIONS (used i n t e x t , f i g u r e s , t a b l e s , p l a t e s , and appendices) ABBREV. Ab  ASSOCIATED FORMULA OR MEANING  FULL NAME albite  (Na[AlSi30e])  Act  actinolite  (Ca (Mg, F e ) 5 [ S i 8 0 2 ] ( 0 H , F ) )  Anda  andalusite  (Al Si0 )  Ands  andesine  (30-50* A n o r t h i t e )  Ank  ankerite  (Ca(Mg,Fe ,Mn)(C03) )  Amph  amphibole  a c t , trem, hnbd, parg  An  anorthite  (Ca[Al2Si208D  Ask  aluminium s i l i c a t e s  anda, s i l l , ky  Bio  biotite  (K2(Mg, F e ) - 4 ( F e , A l , T i ) - 2 [ S i 6 - 5 A l 2 - 3 0 2 0 ] ( O H , F ) )  Cc  calcite  (CaC03)  Chl  chlorite  Ctd  chloritoid  Clz  clinozoisite  Cord  cordierite  Ep Felsic Gn Graph Hnbd Ilm Kspar Ky  + 2  2  2  2  5  +2  2  + 2  + 3  6  ((Mg,  0  4  Al,Fe)i [(Si, Al) 020](0H)i ) 2  8  6  ( ( F e , M g , Mn)2(Al, F e ) A l 3 0 2 [ S i 0 4 ] 2 ( 0 H ) 4 ) +2  +3  (Ca2Al-Al 03-0H-Si207'Si04) 2  (Al3(Mg, F e ) [ S i s A 1 0 i 8 ] ) + 2  2  epidote  (Ca2Fe Al20-0H"Si207"Si04) +3  f e l d s p a r or q u a r t z  f e l s i c minerals garnet-almandine  (Fe3 Al Si30i ) + 2  2  graphite hornblende  2  2  (C) ((Na,K)n-iCa2(Mg, F e , F e , Al)5[Si6-7Al2-10221(OH, F ) 2 ) + 2  + 3  (FeTi03)  ilmenite Potassium f e l d s p a r  (K[AlSi 0 ]) 3  kyanite  8  (A12S105)  Mgt  magnetite  (Fe Fe 204)  Muse  muscovite  (K2Al4[Si6Al2O20](OH, F ) 4 )  Olig  oligoclase  (10-30* A n o r t h i t e )  olivine  (Mg2Si04-Fe Si04)  01 Opaque Opx  opaque m i n e r a l s  + 2  + 3  2  i l m e n i t e , magnetite, p y r i t e (MgSi03-FeSi03)  orthopyroxene  xvii  Structural Geology of Part of the Crooked Late Area. Quesnel Highlands. British Coluwbia ABBREV.  ASSOCIATED FORMULA OR MEANING  FULL NAME  Para  paragonite  Parg  pargasite  Plag  plagioclase  (Na2Al4tSi6Al2020](OH, F>4) ((Na,  K)o-iCa (Mg, F e , F e , A l ) 5 [ S i 6 - 7 A l 2 - l 0 2 ] ( O H , F ) ) + 2  + 3  2  2  2  (Na[AlSi308]-Ca[Al Si 08]) 2  Py  pyrite  (FeS )  Qtz  quartz  (Si0 )  Rutile  rutile  (Ti0 )  2  2  2  2  Serp  serpentine  (Mg [Si205](0H)4)  Sill  sillimanite  (Al Si0 )  3  2  5  (CaTi[Si04](0,0KF))  Sphene  sphene  Staur  staurolite  ( ( F e , Mg) (Al, Fe )g06[Si0 ]4(0,0H) )  Tour  tourmaline  (Na(Mg, Fe, Mn, L i , A l ) 3 A l 6 [ S i 6 0 l 8 ] (B03>3(0H, F)4>  Trem  tremolite  (Ca2Mg [Si80 2](0H,F)2)  Vap  vapour phase  water or carbon d i o x i d e  Zo  zoisite  + 2  + 3  2  4  5  2  (Ca Al"Al203"0H"Si207"Si04) 2  xviii  2  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia ACKNOWLEDGEMENTS I  am t r u e l y i n d e b t e d t o a l l t h e many people t h a t helped me t o come t o t h e  p o i n t of completing t h i s work. F i r s t of a l l , my a p p r e c i a t i o n goes t o my primary advisor,  J . V. Ross.  If  it  were not f o r  all  o f t h e debates,  discussions,  and  v a l u a b l e i n s i g h t s shared, t h e p a t h t o proceed on c o u l d never have been as c l e a r . my o t h e r  faculty  advisors,  K.C.  McTaggart  encouragement and support so f r e e l y g i v e n .  and R.L.  Armstrong,  for  the  To kind  To H.J. Greenwood and T.H. Brown f o r  i n t r o d u c i n g me t o aspects o f metamorphism and phase s t u d i e s , t h a t w i l l c o n t i n u e t o i n s p i r e my i n t e r e s t fundamental sciences.  for  importance  many years t o of  come,  a s t r o n g mathematical  r e i n t r o d u c i n g me t o  background  i n the  staff,  and e s p e c i a l l y  fellow  Also,  the  geological  I would l i k e t o thank J . V. Ross and (lU.C. Barnes f o r c r i t i c a l l y  and h e l p i n g t o improve my e a r l y d r a f t s . faculty,  and f o r  reading  I am g r a t e f u l t o a l l t h e o t h e r  students  at  the University  of  British  Columbia t h a t have helped me more t h a n t h e y may r e a l i z e . I would a l s o l i k e t o thank A.' J . Hynes, D. F r a n c i s , E. W. Mont j o y , R. Hesse a t McGill  University  phenomena.  who so e x p e r t l y  introduced  me t o  the  world  of  geological  And t o R. B. Campbell, L. C. S t r u i k , a l l t h e people a t t h e 6. S. C. and t h e  G. S. C. l i b r a r y , M. Hauseux, R. B. Lemire, A. Sharron, Zhou Nan Shuo, and my parents I want t o express a p p r e c i a t i o n f o r a l l t h e help I have r e c e i v e d . And t o Sadie,  a  Macintosh-XL", and George, an Apple I I + " , f o r t h e i r f a n t a s t i c c o n t r i b u t i o n . F i n a l l y t h i s work has been completed w i t h f i n a n c i a l support f r o m N.S.E.R.C. J. V. Ross (A-2134) and t h i s i s g r e a t l y a p p r e c i a t e d .  xix  to  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Coluwbia  ...It is part of the martyrdom which I endure for the cause of the Truth that there are seasons of mental weakness, when Cubes and Spheres flit away into the background of scarce possible existences; when the Land of Three Dimensions seems almost as visionary as the Land of One or None; nay. when even this hard wall that bars me from my freedom, these very tablets on which I am writing, and all the substantial realities of Flatland itself, appear no better than the offspring of a diseased imagination, or the baseless fabric of a dream. - from  FLATLAND,, ft ROMANCE OF MANY DIMENSIONS , E. A. Abbott -  XX  Stiuctuxal Geology of Puxt of the  Ciookcd Lake  Axca. Quesnel Highlands, British Colunbia  INTRODUCTION L o c a t i o n and Access The  Crooked Lake area  is  l o c a t e d 60 m i l e s east  e a s t - c e n t r a l B r i t i s h Columbia ( F i g u r e c e n t e r s approximately a t l o n g i t u d e a Noranda mining town  to  W i l l i a m s Lake  T h i s 25 square k i l o m e t e r  120° 4 5 ' and  30 k i l o m e t e r s  area t o Crooked Lake.  1).  of  the  Figure 2 i l l u s t r a t e s  l a t i t u d e 52° 1 5 ' .  south,  is  in  map-area  Hendrix Lake,  the closest  populated  t h e exact l o c a t i o n and a r e a l e x t e n t  of t h e area mapped. Crooked Lake can be approached f r o m e i t h e r  of  two d i r e c t i o n s  via  well  maintained l o g g i n g roads t h a t extend as f a r as H o r s e f l y t o t h e west and Canim Lake t o the south; t h e west  paved  roads  connect these  two  towns w i t h t h e Cariboo Highway t o  ( F i g u r e s 1 and 2 ) . Physiography and G l a c i a t i o n  Crooked Lake l i e s i n t h e Quesnel Highlands o f t h e 1964).  This  region i s t y p i f i e d  5500 t o 7000 f e e t be c o n s i d e r a b l y  in elevation.  by  gently r o l l i n g  Glacial  steeper t h a n t h e i r  I n t e r i o r Plateau  ridge-tops  that  (Holland  range  from  a c t i v i t y has caused t h e v a l l e y w a l l s t o  corresponding r i d g e - t o p s .  Average  local  r e l i e f ranges f r o m 3000 t o 3500 f e e t . An a x i s o f t h e l a t e s t two g l a c i a l advances o c c u r r e d i n t h e Cariboo Mountains t o t h e n o r t h e a s t ( T i p p e r 1971).  I c e must have f l o w e d across t h e Crooked Lake area  toward t h e west and southwest t o  reach t h e I n t e r i o r P l a t e a u (see F i g u r e 3 ) .  of  the g l a c i a l  though local  high  striae  and d e p o s i t s  observed  s t a n d i n g rock u n i t s and prominent  controls  on  ice  movement d i r e c t i o n .  Page 1  confirm  this  rock s t r u c t u r e  Most  general d i r e c t i o n , were  important  52° 30'  Bid Ita.  /  V  V  120°  120° | 30*  45'  Page 3  Structural Seoloov of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Extensive  valley  glaciation  Numerous n o r t h - f a c i n g c i r q u e s , systems o f a r e t e s and horns, to this  Figure 3  is  characteristic  steep w a l l e d  and y e a r - r o u n d  of  more  *U-shaped' v a l l e y s i c e accumulations  recent  times.  (see F i g u r e 4 ) ,  above 7000' a t t e s t  on-going process.  D i r e c t i o n o f i c e movement o f Fraser I c e Sheet and l a t e i c e re-advances i n C e n t r a l B r i t i s h Columbia ( f r o m Tipper 1971, p. 39) P r e v i o u s and C u r r e n t Work Geologic  mapping  took  place  as  early  as  1889  to  B a r k e r v i l l e area (Bowman 1889) and 1927 j u s t 30 k i l o m e t e r s  Page 4  t h e northwest i n t h e to  t h e east i n t h e  Structural Ecology of Part of the Crooked Lake Urea. Quesnel Highlands. British Colunbia Clearwater Lake area Crooked Lake area  (Marshal 1927), though no s y s t e m a t i c work i s reoorded f o r t h e  u n t i l R.B.  Campbell's reconnaissance mapping o f t h e  1960's (Campbell 1963 and 1978).  Campbell recognised a major s t r u c t u r a l  (two a n t i f o r m s and an i n t e r v e n i n g  sequence  synform) i n v o l v i n g u n i t s r a n g i n g i n age from  Precambrian t o J u r a s s i c .  It  boundary  g e o l o g i c p r o v i n c e s o f t h e Canadian C o r d i l l e r a  between two  major  early  was  believed t h a t t h i s  sequence s t r a d d l e d  the  - the  Omineca G e a n t i c l i n e t o t h e east and t h e Intermontane B e l t t o t h e west.  Figure 4  -  G l a c i a l v a l l e y s t y p i c a l o f t h e n o r t h e a s t e r n slopes o f Eureka S y n c l i n e  K. \1. Campbell (1971) mapped t h e Crooked Lake area a t a scale o f one m i l e  paying  petrochemistry. mentioned  close  attention  He found f o u r  structural  sequence,  to  major l i t h o l o g i c  major  rock  much i n  units  contacts,  represented  accord w i t h R.B.  Page 5  one i n c h  petrology, in  the  Campbell's  and above  earlier  to  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia observations.  In  addition,  he noted t h a t c o n t a c t s between t h e u n i t s  d i s c o r d a n t ( p o s s i b l e low angle t h r u s t i n g ) occurred  during  and t h a t d e f o r m a t i o n  and metamorphism  one p r o g r e s s i v e episode i n v o l v i n g a l l rock u n i t s .  are s i g n i f i c a n t i n  that  they  l i n k the h i s t o r i e s of  two  were  These f i n d i n g s  contrasting  geologic  p r o v i n c e s a t l e a s t s i n c e t h e Mesozoic (Campbell, K.V. 1971). The present author and f o u r o t h e r m a s t e r s ' s t u d e n t s a t t h e U n i v e r s i t y B r i t i s h Columbia have undertaken t o by K.V.  examine  p a r t s o f and beyond t h e area covered  Campbell (1971) w i t h c l o s e a t t e n t i o n being p a i d t o d e t a i l e d  f i e l d relations(see Figure 2 ) . responsible f o r the  D. E l s b y ,  structurally  of  J. F i l l i p o n e ,  and J .  structural  Montgomery were  u n d e r l y i n g Precambrian Kaza Group s t r a t a and  upwards i n t o t h e S l i d e Mountain Group r o c k s .  M. A. Bloodgood has examined t h e Upper  T r i a s s i c t o J u r a s s i c core r o c k s o f t h e Eureka S y n c l i n e , paying c l o s e a t t e n t i o n t o v o l c a n i c s t r a t i g r a p h y and provenance.  The present author has covered p a r t s o f t h e  o v e r l y i n g T r i a s s i c / J u r a s s i c u n i t s and worked downwards i n t o t h e s t r u c t u r a l p i l e as f a r as and s l i g h t l y below t h e Kaza Group/ S l i d e Mountain Group c o n t a c t .  Page 6  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia GENERAL GEOLOGY Regional Geology The Crooked Lake map area i s l o c a t e d i n t h e southern p o r t i o n o f t h e Canadian Cordillera; (1967,1970) (1964).  this that  r e g i o n has been d i v i d e d i n t o 5 t e c t o n i c roughly coincide  Three o f these b e l t s  with  (Rocky Mountain,  metamorphic t o rock  units  plutonic of  Plutonic)  by Wheeler  t h e major landforms o u t l i n e d by Intermontane,  composed o f o n l y s l i g h t l y metamorphosed s u p r a s t r u c t u r e t h e r e s t (Omineca and Coast  belts  are formed  Holland  and I n s u l a r )  are  and t h e two t h a t comprise of a mixture of high-grade  i n f r a s t r u c t u r e and low metamorphic s u p r a s t r u c t u r e .  t h e present  study occur on t h e  boundary  of  The  t h e Omineca  C r y s t a l l i n e B e l t and t h e Intermontane Zone (see F i g u r e 5 ) . Geologic demonstrated  mapping  between  t h a t rock u n i t s a t l e a s t  across t h e two zones (Campbell e t platformal basement  t h e Rocky Mountain  carbonates  t h a t continues  al.  up  to  1973).  and  Omineca b e l t s  has  lower P a l e o z o i c are continuous These  largely  miogeoclinal/  and c o n t i n e n t a l l y - d e r i v e d e l a s t i c s r e s t on c o n t i n e n t a l as p a r t o f t h e c r a t o n , i n a s t r i c t sense, o n l y  Rocky Mountain Trench (Mereu e t a l . 1977).  Beneath t h e Omineca rocks  up t o  the  Precambrian  basement has been i d e n t i f i e d i n t h e Shushwap T e r r a i n (Duncan 1984), though seismic studies indicate that i t s  characteristics  (e.g.  - thickness,  seismic  velocity)  change markedly f r o m east t o west ( B e r r y and F o r s y t h 1975). Compared t o t h e r e l a t i v e l y s i m p l e i m b r i c a t e  thrusting  t h e Rocky Mountain b e l t , t h e r o c k s o f t h e Omineca G e a n t i c l i n e much more complex north-south  deformational  and  metamorphic  and open f o l d i n g o f have  history.  experianced a Several  broad  t r e n d i n g a n t i c l i n o r i a and s y n c l i n o r i a a l t e r n a t e across a major p a r t o f  t h e b e l t from east t o west; these s t r u c t u r e s are g e n e r a l l y t h i r d i n a s e r i e s  Page 7  of  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia  Figure 5  -  T e c t o n i c s u b d i v i s i o n s o f t h e Canadian C o r d i l l e r a showing present study area (adapted f r o m T e c t o n i c Assemblage Hap o f t h e Canadian C o r d i l l e r a , T i p p e r e t a l . 1981)  Page 8  Structural fieology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia fold  forms, t h e e a r l i e s t o f whioh i s  limb  l e n g t h s on t h e  order  of  thought  oomprise reoumbent  s e v e r a l k i l o m e t e r s (Ghent e t  Journeay 1982; P e l l and Simony 1982).  nappes  with  a l . 1977; Murphy and  Metamorphism t h r o u g h o u t t h e b e l t ranges  from lower  greenschist  metamorphic  core complexes are unroofed  al.  to  t o upper a m p h i b o l i t e and t o t h e south i n i n the  the  belt,  Monashee Complex ( C r i t t e n d e n e t  1980; Brown and Read 1983; O k u l i t c h 1984). The boundary o f t h e Omineca b e l t w i t h t h e Quesnel s u b - t e r r a n e o f  Intermontane zone i s c h a r a c t e r i z e d by i n t h e Omineca b e l t . thrust  Tipper  1970; Travers 1978).  1978;  s t r u c t u r a l c o m p l e x i t y s i m i l a r t o t h a t seen  T h i s i s remarkable s i n c e f u r t h e r i n t o t h e Intermontane zone  simple  mylonite  the eastern  faulting  development  and g e n t l e f o l d i n g are more c h a r a c t e r i s t i c (Campbell and Thrust  faulting,  tectonic  are very common along t h i s zone  imbrication,  and  (Campbell 1971; Montgomery  Ross 1981; Brown and Read 1983). Perhaps  ubiquitous  the  belt  of  most s t r i k i n g f e a t u r e o f u l t r a m a f ios,  l o c a l l y obducted  1978;  Rees  1981).  on  This  to  Omineca/Quesnel boundary  amphibolites, basalts,  oceanic a f f i n i t y t h a t some have suggested crust  the  is  a  and sediments o f s t r o n g  i s t h e remains o f a l a t e Paleozoic ocean  the miogeoclinal rocks t o the  b e l t can be found  east  (Montgomery  c o n s i s t e n t l y from north  to  south  s e p a r a t i n g t h e rock t y p e s o f t h e two p r o v i n c e s (see F i g u r e 6 ) . The Quesnel rocks c o n s i s t carbonates, p o s s i b l y f o r m i n g a upper Paleozoic r o c k s  of  volcaniclastics,  Late  (Monger 1977;  volcanics, a r g i l l i t e s ,  T r i a s s i c subduction Travers  arc  1978).  and  complex formed on  Examination of  faunal  d i s t r i b u t i o n s and paleomagnetic d e t e r m i n a t i o n s i n rocks o f Permian t o J u r a s s i c age suggest t r a n s o u r r e n t displacements r e l a t i v e t o s i m i l a r rock t y p e s i n North America on t h e o r d e r o f one t o two thousand k i l o m e t e r s  Page 9  (Monger e t  al.  1982).  T h i s would  structural Geology of Part of the crooked Lake Area, Quesnel Highlands. British Coluwbia  Figure 6  -  The Okanagan P l u t o n i c and Metamorphic Complex: major s t r u c t u r a l components and t h e Quesnel - N o r t h America s u t u r e zone ( F i g u r e 4 of O k u l i t c h 1984, p.1181) Page 10  Structural Geoloov of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia imply t h a t development o f an i s l a n d aro  s e t t i n g f o r t h i s t e r r e n e may n o t have an  immediate t e c t o n i c r e l a t i o n s h i p t o t h e N o r t h American s i t u a t i o n t h a t developed i n t h e e a r l y Mesozoic. Certain  rock  types occurring  w i t h i n or across t h e two  i m p o r t a n t evidence t h a t t h e y have shared a common h i s t o r y a t Mesozoic.  The most n o t a b l e  example  northwest i n t h e Intermontane b e l t ; d e t r i t u s t h a t could (Eisbacher  of t h i s  belts  provide  l e a s t since the l a t e  i s i n t h e Bowser Basin t o t h e  Lower Cretaceous d e p o s i t s c o n t a i n metamorphic  o n l y have been d e r i v e d from Omineca b e l t rocks t o t h e  1974; Monger e t a l . 1978).  l i n k s t h e h i s t o r i e s o f t h e two  east  I n addition, a period of i n t r u s i v e a c t i v i t y  belts;  these are t h e "100 m. y . " i n t r u s i v e s  of  Campbell and T i p p e r (1970). The  most  volcaniclastic  recent  activity  history  has  f o l l o w e d by  seen  extensive  Miocene  to  Extensive Quaternary g l a c i a l d e p o s i t s f r o m a t l e a s t  Eocene  volcanic  Pliocene plateau three  distinct  and  basalts.  events cover  l a r g e p a r t s o f t h e r e g i o n ( T i p p e r , 1971). L o c a l Geology The f o u r rock u n i t s i d e n t i f i e d by R. B. Campbell (1971) are, Kaza group,  Campbell (1963)  in stratigraphic/structural  and examined by K.V.  succession,  t h e Pennsylvanian t o Permian A n t l e r Formation,  the  Proterozoic  a micaceous q u a r t z i t e  and grey t o b l a c k p h y l l i t e s o f probable Upper T r i a s s i c t o Lower J u r a s s i c age, and a Lower units,  Jurassic with  volcanic/volcaniclastic  minor  variations,  F i g u r e 6 ) and has been d e s c r i b e d 1957 & 1963; Campbell e t  assemblage.  continues  to  This  same sequence  of  t h e northwest and southeast (see  and dated by numerous workers ( S u t h e r l a n d Brown  a l . 1973; S t r u i k 1980; Rees 1981; Uglow 1921; Campbell and  T i p p e r 1971; Orchard & S t r u i k 1985).  Page 11  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia All  rock  units  have been  f o l d s - Perseus A n t i c l i n e , K.V. 1971).  in  Eureka S y n c l i n e ,  B a r r o v i a n metamorphism  these s t r u c t u r e s , 1971).  involved  though e a r l i e r  possibly  l a t e stage,  northwest  trending  Boss Mountain A n t i c l i n e (Campbell, ooincided  w i t h t h e development  events c o u l d a l s o be present  (Campbell,  of  K.V.  North t o n o r t h e a s t t r e n d i n g f o l d s deform a l l e a r l i e r s t r u c t u r e s . Late  events  effecting  t r e n d i n g h i g h angle f a u l t s . deposits i n the v a l l e y  t h e u n i t s a t Crooked  Tertiary olivine  include  northeast  b a s a l t , and t h i c k (30-50 m) g l a c i a l  bottoms and low l y i n g r e g i o n s .  Page 12  Lake  Structural Geology of Part of the Crooked Lake area, Quesnel Highlands, British coluwbia STRATIGRAPHY Introduction In  t h e Crooked Lake area t h e present author has f u r t h e r separated t h e f o u r  l i t h o l o g i e s o f R.B. Campbell  (1963) and K.V. Campbell (1971) i n t o f i v e  distinct  u n i t s on t h e b a s i s o f c o l o u r ,  t e x t u r e s , and mineralogy. The  unit,  micaceous  quartzite,  additional  a  was o r i g i n a l l y i n c l u d e d w i t h t h e black p h y l l i t e u n i t of K.V.  Campbell (1971). I n t h i s r e p o r t , these two u n i t s s h a l l be r e f e r r e d t o as t h e Eureka Q u a r t z i t e and t h e Crooked Lake P h y l l i t e , In the  low l y i n g r e g i o n s ,  u n i t s were never  respectively.  where g l a c i a l cover i s  clearly  observed  s i g n i f i c a n t , contacts  (see F i g u r e 7b; note: a l l  between  subsequent  photographs i n t h e t e x t w i l l i n d i c a t e t h e d i r e c t i o n a photograph was taken, as an azimuth  {DIR-045}  {L0C-J11}).  and,  where  applicable,  its  location  as  a  station  As t h e g e o l o g i c map ( P l a t e 1) shows, c o n t a c t s across t h e  number  southwestern  p o r t i o n o f t h e area were i n t e r p o l a t e d f r o m o u t c r o p s o f t h e v a r i o u s l i t h o l o g i e s . Although, c o n t r o l f o r t h e placement o f these c o n t a c t s i s poor i n places, i t b e l i e v e d they have t h e  best p o s s i b l e c o n f i g u r a t i o n  is  f o r the d i s t r i b u t i o n of the  a v a i l a b l e given data. The  steep slopes n o r t h e a s t o f Crooked Lake,  e x c e l l e n t o p p o r t u n i t y t o observed d i s t a n c e s (see F i g u r e 7a  the  and P l a t e 1 ) .  on t h e o t h e r hand,  u n i t s ' contacts The  exposed  offered  an  f o r considerable  two lowest c o n t a c t s were seen t o be  t i g h t l y i n t e r f i n g e r i n g i n p l a c e s ( w i t h i n a zone o f a few meters t h i c k n e s s ) , though o t h e r w i s e t o be s h a r p l y p l a n a r . interfingering, contacts.  as w e l l ,  The uppermost  though r e l a t i o n s  contact  ( F i g u r e 7 c ) shows obvious  are not as c l e a r  c u t as t h e  lower  The middle c o n t a c t between t h e Eureka Q u a r t z i t e and t h e Crooked Lake  Page 13  F i g u r e 7 - C o n t a c t s o f t h e Crooked Lake rock u n i t s  T a k l a c o n t a c t zone  i s assumed f r o m K.V.  Campbell (1971) {DIR-045}  F i g u r e 7c  -  Happed c o n t a c t s between Crooked Lake P h y l l i t e and Takla i n t h e n o r t h e a s t e r n c o n t a c t zone; note p o s s i b l e p h y l l i t e i n f o l d a t t o p r i g h t r e F i g u r e 16d {DIR-318}  Page 15  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Phyllite  was n o t  seen exposed;  t a l u s f r o m t h e r a p i d l y e r o d i n g p h y l l i t e b u i l d s up  above t h e more r e s i s t a n t q u a r t z i t e and obscures t h i s s u r f a c e . Plate fine  1 does not show i n t e r n a l s u b d i v i s i o n f o r t h e  scale o r i g i n a l  g r a d a t i o n and i n t e r f i n g e r i n g  Crooked Lake  (most l i k e l y  due t o  units; ductile  response o f s u b u n i t s and complex f o l d i n g ) occurs on a s c a l e t h a t i s impossible t o show on t h e  map.  I n o r d e r t o present t h e i n t e r n a l s u b d i v i s i o n s o f these u n i t s  structural/stratigraphic STRUCTURE,  below)  columns were c o n s t r u c t e d once t h e l a t e r  large-scale  structural  features  diagrams (see P l a t e 1 and P l a t e 4 ) are o r i e n t e d , direction  of  original  lithologic  were  that  understood;  as much as p o s s i b l e ,  It  must  placement,  thicknesses  (for  be s t r e s s e d ,  and  any  should  unit  or  not  be  subunit)  interpreted nor  as  probable  their  existing  suggesting  original  original  stratigraphic  successions f o r i n t e r n a l s u b u n i t s o f t h e major l i t h o l o g i e s . Appendix  A contains  rock d e s c r i p t i o n s r e f e r e n c e d t o segments o f t h e s t r u c t u r a l / s t r a t i g r a p h i c ( P l a t e 4 ) and t o Below  i n the  s i n c e t h e e a r l i e r s t r u c t u r a l f e a t u r e s c o u l d not be removed, these  columns merely o u t l i n e t h e t h i c k n e s s e s o f e x i s t i n g s u b u n i t s and relative  these  v a r i a t i o n and do r e p r e s e n t a s t r a t i g r a p h i c  succession w i t h r e s p e c t t o t h e major l i t h o l o g i c u n i t s . however,  ( p o s t D2; see  station  l o c a t i o n s shown on t h e g e o l o g i c map ( P l a t e 1 ) .  i s an account o f  ages,  distributions,  thicknesses,  o r i g i n , and c o n t a c t r e l a t i o n s h i p s o f t h e f i v e u n i t s a t Crooked Lake. map ( P l a t e 1 ) ,  the  columns  s t r u c t u r a l / s t r a t i g r a p h i c columns  (Plate 4),  sub-units, The g e o l o g i c  and Appendix A  should be r e f e r r e d t o d u r i n g t h e course o f t h i s d i s c u s s i o n . Kaza Group - Snowshoe Formation This  unit  i s b e l i e v e d t h e o l d e s t exposed i n t h e  P r o t e r o z o i c stems f r o m R.B. Campbell  map-area. An age of Late  e t a l . (1973) who have c o r r e l a t e d i t w i t h t h e  Page 16  Structural Geology of Part of the Crooked Lake area. Quesnel Highlands. British Coluwbia middle M i e t t e Group o f t h e same gross  lithology.  (Sutherland Brown feldspathic  grit  age i n  t h e Rooky Mountain b e l t on t h e b a s i s o f  The t y p e area f o r t h e Kaza i s Bowron Lakes P r o v i n c i a l Park 1963); t h e r e , t h e 12,000 f o o t t h i c k u n i t c o n s i s t s interlayered  with  schist  and  greenish-grey  o f unsorted,  to  dark  grey  phyllite.  Figure 8  -  In structures  I n t e r l a y e r e d p l a g - b i o - q t z s c h i s t and muse q u a r t z i t e t y p i c a l of t h e Snowshoe Formation i n t h e Crooked Lake area {DIR-350,L0C-RZ10} the and  map-area underlies  the the  southernmost p a r t o f t h e area.  Kaza  occurs i n  synforms; K.V. Campbell  Page 17  the  cores  outcrops (1971) has  are  of  all  antiformal  restricted  estimated  to  the  t h e exposed  structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Colunbia t h i c k n e s s o f t h e Kaza i n t h e feet;  since  unit to  Crooked Lake  area as being between 15,000 and 30,000  very l i t t l e s t r a t i g r a p h i c o r s t r u c t u r a l d e t a i l i s known about t h e  date  it  i s d i f f i c u l t t o ascertain the  amount  of  tectonic thickening  t h i s f i g u r e might i n c l u d e ( i t i s , though, expected t o be a minimum o f 100% because c o m p o s i t i o n a l l a y e r i n g i s a transposed f o l i a t i o n , see STRUCTURE below). Snowshoe  r o c k s c o n s i s t predominately o f i n t e r l a y e r e d  and mica q u a r t z i t e qtz-plag-mica schist  with  This  unit  i.e.,  of mica-plag-qtz  to  in  r a n g i n g f r o m very f i n e  (millimeters)  t o very  banding  composed  of c r y p t o c r y s t a l l i n e  perthite  material  porphyroblasts (these  are  best  and a seen  t h e southwestern p o r t i o n o f t h e map a r e a ; r e f e r t o F i g u r e 3 8 a ) . l i t h o l o g i e s i n c l u d e p e l i t i c marbles,  qtz-ep-hnbd s c h i s t ,  s c h i s t , and dark p h y l l i t e ( o r very f i n e g r a i n e d s c h i s t ) . are found r e s t r i c t e d t o two 30 main s c h i s t ;  grains.  meter  t h i c k bands o f mica s c h i s t and marble w i t h i n  muscovite d e f i n e s a weak f o l i a t i o n and q u a r t z occurs  These marbles show banding (composed o f  below t h e marble band on t h e qtz-ep-hnbd  developed c o m p o s i t i o n a l Chl-rich schists  northeastern side  s c h i s t crops o u t ;  chl-rich  Coarse g r a i n e d marbles  very f i n e  of  the lake,  as rounded  c a l c i t e and minor  muscovite; r e f e r t o F i g u r e 48) s i m i l a r t o t h a t seen i n t h e s c h i s t .  of  coarse  F i g u r e 8 shows a t y p i c a l exposure o f t h i s rock t y p e . The o n l y o u t s t a n d i n g  Minor  the  and  coarse g r a i n e d w i t h l a y e r i n g between t h e  t e x t u r a l f e a t u r e s t h i s u n i t d i s p l a y s l o c a l l y are fine  schist  q t z - p l a g - m i o a s c h i s t i s a rock w i t h q t z i p l a g _  i s medium  gradational l i t h o l o g i e s (meters).  horizons  schist  ( n o t e : m i n e r a l names used t h r o u g h t h e t e x t are g i v e n i n a  •least-to-most format', mica).  subordinate  plag-mica-qtz  Structurally  a 40 meter t h i c k n e s s  t h i s u n i t i s medium t o coarse g r a i n e d w i t h w e l l  layering  of  epidote  and  quartz/hornblende.  h o r i z o n s are d i s t i n c t i v e because o f t h e i r c o l o u r d i f f e r e n c e ,  Page 18  but  Structural ecology of Part of the crooked Lake Area, Quesnel Highlands. British colunbia F i g u r e 9 - Snowshoe/Antler c o n t a c t  F i g u r e 9a  -  Sharply d e f i n e d c o n t a c t between Snowshoe Formation A n t l e r Formation (above) {DIR-03aL0C-J112}  F i g u r e 9b  -  Snowshoe s l i v e r w i t h i n A n t l e r plag-hnbd s c h i s t and chl-hnbd s c h i s t ; s l i v e r i s p a r t o f a D2 f o l d form i n v o l v i n g t h e c o n t a c t between t h e two u n i t s ; s i m i l a r f e a t u r e i s shown i n F i g u r e 12 {DIR-020,L0C-J114} Page 19  (below)  and  Structural 6cology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia do  not e s s e n t i a l l y  o n l y mica,  d i f f e r f r o m t h e main s o h i s t package ( i . e . o h l  but f e l s i c s  predominate).  Rare dark p h y l l i t e s  i s the  main or  (very f i n e  grained  s c h i s t s ) were found i n t h e southwestern map area and are b e l i e v e d t o r e p r e s e n t a true  Snowshoe s u b - l i t h o l o g y  as opposed t o  being  a structural  infold  of  the  o v e r l y i n g , younger Crooked Lake P h y l l i t e ( t h e o n l y l i k e l y source i n t h e area f o r this lithology). Kaza quartz  r o c k s probably o r i g i n a t e d as a sequence o f immature  arenites,  q u a r t z arkoses,  f l u v i a l environment. carbonate  The minor  and q u a r t z  wackes d e p o s i t e d  rook t y p e s  may  represent  to  submature  i n a nearshore organic-related  accumulations ( t h e marble and p o s s i b l y t h e qtz-ep-hnbd s c h i s t ) and/or  l o c a l i z e d voloanic a o t i v i t y (the qtz-ep-hnbd s c h i s t ) . The lower c o n t a c t o f t h e Kaza Group i s not seen anywhere i n t h e Crooked Lake area.  Further  to  the east,  though,  above t h e pre-Hadrynian Malton  the correlative  Gneiss,  (Ghent  H o r s e t h i e f Creek Group l i e s  et  al.  1977),  which  may  r e p r e s e n t Archean basement t o b o t h t h e s e u n i t s . The  upper  Kaza c o n t a c t i s exposed t h r o u g h o u t h a l f  clearly inferred f o r the rest.  This surfaoe  i s sharp  of  t h e map-area  and  against the overlying  A n t l e r rocks ( F i g u r e 9a) and a t one l o c a l i t y t i g h t f o l d i n g i n v o l v e s t h e  contact  ( F i g u r e 9b; t h i s f e a t u r e i s very l i k e l y a D2 f o l d form, see STRUCTURE b e l o w ) ; t h i s causes an apparent r e p e t i t i o n o f t h e d i f f e r e n t u n i t s contact.  T h i s geometry suggests t h a t t h e  lithologies within  t h e Kaza* r e p o r t e d by K. V. Campbell  o f t h i s same t i g h t f o l d i n g ( e . g . , lensoid  'tectonic  bodies w i t h i n t h e Kaza).  in  the  slices  v i c i n i t y of the of  Antler-like  (1971) are m a n i f e s t a t i o n s  r o o t l e s s f o l d hinges o f A n t l e r appearing as Even though s t r u c t u r e s t o e i t h e r s i d e o f t h i s  c o n t a c t were found t o be c o n s i s t e n t l y concordant ( w i t h i n reasonable e r r o r ) w i t h i n  Page 20  Structural fieology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia t h e map area, t h e degree t o which t h e adjaoent rooks have been f o l d e d and p o s s i b l y m y l o n i t i z e d i n d i c a t e s t h a t some amount o f s e p a r a t i o n must be a s s o c i a t e d w i t h t h i s s u r f a c e ; numerous r e s e a r c h e r s (Campbell, K. V. 1971; Rees and F e r r i 1983; Montgomery 1978;  S t r u i k 1981), i n c l u d i n g t h e present a u t h o r , b e l i e v e t h a t t h i s u n i t i s i n f a u l t  c o n t a c t w i t h t h e o v e r l y i n g A n t l e r Formation. S l i d e Mountain Group - A n t l e r Formation The A n t l e r Formation was f i r s t d e f i n e d by S u t h e r l a n d  Brown (1957 and 1963)  when he m o d i f i e d f o r m a t i o n s o f t h e S l i d e Mountain Group proposed by Johnson and Uglow (1926). R i v e r by in  Recent work i n  S t r u i k (1981)  the type  area n o r t h o f B a r k e r v i l l e and t h e Cariboo  has y i e l d e d Pennsylvanian and Permian ages f o r  c h e r t o f t h e A n t l e r Formation (Orchard and S t r u i k 1985).  types i n c l u d e argillaceous  pillow basalt, chert,  slate,  diorite,  minor gabbro  and greywacke.  t h e S l i d e Mountain Group r o c k s t h r o u g h o u t  There, and  conodonts  t h e major rock  ultramafic  rocks,  F i g u r e 6 shows t h e d i s t r i b u t i o n of  c e n t r a l B r i t i s h Columbia and i n r e l a t i o n  t o t h e map-area. Antler  rocks everywhere separate t h e Kaza Group f r o m  Q u a r t z i t e and Crooked Lake P h y l l i t e .  t h e o v e r l y i n g Eureka  I n t h e western p a r t o f t h e  maximum present t h i c k n e s s o f 1200 meters i s e s t i m a t e d f o r t h e  hinge  map-area a  r e g i o n of t h e  a n t i f o r m / s y n f o r m p a i r shown i n P l a t e 3 ( t h i s f e a t u r e on t h e western f l a n k o f t h e Boss Mountain A n t i c l i n e s h a l l be h e n c e f o r t h c a l l e d t h e B a s s e t / S t a r k pair);  t h i n n i n g occurs w i t h i n t h e u n i t as i t  arches over  t h e Boss  A n t i c l i n e b r i n g i n g i t t o a minimum t h i c k n e s s o f under 300 meters on s i d e o f Crooked Lake (see F i g u r e 10). Campbell  (1971)  characteristic  suggests of t h i s  that  Mapping by R.B. Campbell such  thickening  u n i t o u t s i d e t h e map-area.  Page 21  and  structural Mountain  the northeast  (1978)  thinning  and is  K.V. also  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. B r i t i s h Colunbia  Page 22  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Sediment D e r i v a t i v e s : CEHP Heta-diorite  ^ CPE mta-tttcke  Massive ( m g t ) - c h l - p l a g - e p Meta-wacke and Massive Q u a r t z i t e  Igneous  Derivatives  f oeta-vacke  Rgt-CM-Qtz veins  CEHP Heta-diorite  Massive and C r o s s - f r a c t u r e d c h l - e p - h n b d - p l a g M e t a - D i o r i t e  Metamorphic Types  *tf/Z/ff/ff/J/f/f.*  sss/s/fs/s///////// //ft*********////ft. Stt/fttS/SStStSttt  y/im senist  "  •'ttttftttttttt •f/tstttttt * *//////•/  'ttfftt 'ttt *  Ep-plag-chl-hnbd s c h i s t t o chl-hnbd s c h i s t  F i g u r e 11  Summary o f t h e p r i n c i p a l A n t l e r l i t h o l o g i e s  Page 23  structural ecology of Part of the crooked Lake Area, Quesnel Highlands, British Columbia The  A n t l e r Formation i n t h e Crooked Lake area i s a  gradational l i t h o l o g i e s .  of  F i g u r e 11 p i c t o r i a l l y o u t l i n e s t h e main s u b - l i t h o l o g i e s  encountered across t h e map a r e a ; t h r e e common appearing  diverse c o l l e c t i o n  *meta-wackes',  the  igneous  t e x t u r a l variants - the  appearing  clastic  "meta-diorites*,  and t h e  metamorphic p h y l l i t e s and s c h i s t s , - are shown. The meta-wackes ( P l a t e s 6c, f ) are c h a r a c t e r i z e d by an abundance o f q u a r t z , very  and e p i d o t e ; t h e y range from  f i n e t o medium g r a i n e d and are g e n e r a l l y l i g h t  They and  feldspar,  are it  is  interlayered  on  a  not  to  find  unusual  phyllitic/schistose  matrix  map  distributed  to  medium  them  ( Figure  abundant i n t h e southwestern c o n t a i n 30-60% evenly  fine  as  in  c o l o u r (see F i g u r e 4 5 ) .  scale  with phyllites/schists  lensoid  11 & P l a t e 6 c ) . area.  dark  The m e t a - d i o r i t e s mafic  aggregate  spots  as  distributed  interlayered  with  cross-cutting  fractures  spotted  evenly  phyllite/schist  'schists'  or  as  in  is  a  most  ( P l a t e s 6a, b, d)  minerals ( c h l o r i t e ,  hornblende)  is  medium t o coarse and t h e  felsic  m a t r i x w i t h green m a f i c  throughout).  This massive  and m g t - e p - q t z v e i n i n g  P h y l l i t e and s c h i s t t o g e t h e r c o n s t i t u t e though they seem t o be  (light  'floating'  This l i t h o l o g y  w i t h p l a g i o c l a s e , e p i d o t e , and q u a r t z ; t h e g r a i n s i z e t e x t u r e i s best d e s c r i b e d  bodies  unit units  is  found  with  numerous  ( F i g u r e 11 & P l a t e s  t h e dominant  lithology  either  6a, b ) .  i n the Antler,  l e s s r e p r e s e n t a t i v e i n t h e southwestern map area.  are f i n e t o medium g r a i n e d q t z - e p - p l a g - c h l - h n b d aggregates w i t h  These very  w e l l developed f o l i a t i o n and o c c a s i o n a l l y f i n e l a y e r i n g . Antler schist,  rocks i n c l u d e as minor l i t h o l o g i e s  and s e r p e n t i n i z e d  peridotite.  t h e meta-wacke l i t h o l o g y as t h i n grained  as  t o appear  bluish  The q u a r t z i t e  quartzite,  calcareous  occurs i n a s s o c i a t i o n w i t h  lenses (< 1 d e c i m e t e r ) and o f t e n i s so f i n e  ' c h e r t y ' ( t h i s may r e p r e s e n t s i l i c i f i c a t i o n o f a very f i n e  Page 24  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia g r a i n e d sediment o r , o o n v e r s e l y , m y l o n i t i z a t i o n o f p r e - e x i s t i n g q u a r t z i t e Medium g r a i n e d calcareous s c h i s t occurs (10-20%)  from  calcite  in  different  j u s t west  of  S t a r k Lake,  as a f a i r l y major p a r t o f t h e  and  does  not  Antler  eastward and n o r t h t o Crooked Lake;  t h e u n i t d e f i n e s a metamorphic l a y e r i n g and events)  unit6>.  occur  the  v e i n i n g (probably  from  w i t h hornblende. Much o f t h i s s c h i s t i s  a l s o a s s o c i a t e d w i t h t h e meta-wacke l i t h o l o g y . One pod o f s e r p e n t i n i z e d p e r i d o t i t e was found i n t h e grained  and  southernmost  highly  f r a c t u r e d (two  calcite respectively). surrounding u n i t s  p a r t o f t h e southwestern map a r e a ;  It  sets  of  it  f r a c t u r e s c o n t a i n s e r p e n t i n e and  i s unknown what r e l a t i o n s h i p  this  u n i t has t o t h e  as no c o n t a c t s were seen.  From t h i s d i s c u s s i o n o f l i t h o l o g i e s i t should be c l e a r t h a t t h e r e generalized d i s t r i b u t i o n of 4,  units  S e c t i o n s l , 2 , 4 and 5 demonstrate  t h e major  i s coarse  within  exists  t h e A n t l e r across t h e map area.  t h i s change.  a  Plate  I n t h e southwest map area a l l o f  u n i t s are r e p r e s e n t e d i n n e a r l y equal p r o p o r t i o n s and two o f t h e minor  u n i t s , q u a r t z i t e and s e r p e n t i n i z e d p e r i d o t i t e , occur l o c a l l y . calcareous  lithology  becomes  more abundant,  To t h e n o r t h ,  the  i n t e r m i x e d w i t h meta-wacke and  s c h i s t ; t h i s i s an area where some degree o f carbonate v e i n i n g occurs and minor sulfides  are  present  (mostly  pyrite).  The A n t l e r  encountered  in  the  n o r t h e a s t e r n map area c o n s i s t s o f m e t a - d i o r i t e s and s c h i s t w i t h a s i g n i f i c a n t l y s m a l l e r p r o p o r t i o n o f meta-wacke. This northeast  lithologic  change w i t h i n t h e body o f t h e A n t l e r  may stem f r o m  an  sediment f a c i e s versus an folding  ( i . e . , causing  original  f r o m southwest  lithologio distribution (i.e.,  e a s t e r n igneous  facies)  a western  or f r o m e a r l y phase t i g h t  l o c a l i z e d r e p e t i t i o n or s t a c k i n g o f  Page 25  to  meta-wacke  units).  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Minor  f e a t u r e s w i t h i n t h e A n t l e r r o c k s suggest t h a t both o f these f a c t o r s have  played a p a r t i n t h e p r o d u c t i o n o f t h i s present d i s t r i b u t i o n .  F i g u r e 12  -  I n t e r f i n g e r i n g o f A n t l e r q t z - p l a g - c h l - h n b d s c h i s t (dark w i t h Eureka Q u a r t z i t e ( l i g h t u n i t ) {DIR-055,L0C-J101}  Because lack  of  of t h e amount o f i n t e r n a l d e f o r m a t i o n undergone by t h i s u n i t and  preservation  of  good primary f e a t u r e s ,  configuration of units i s speculative unit  originated  composition.  unit)  as  at best.  a volcanigenic  The occurrence  of  It  sequence  ultramafics  the nature is of  and very  clear,  of the though,  intermediate fine  grained  i n t e r b e d s would suggest an oceanic s e t t i n g f o r t h i s sequence,  original that this to  basic  sedimentary  and perhaps,  as  Montgomery, (1978) has suggested, an o p h i o l i t e a s s o c i a t i o n . The upper c o n t a c t o f t h e A n t l e r r o c k s i s w e l l exposed on t h e n o r t h e a s t o f t h e f i e l d area ( P l a t e 6 d ) , t h i s s u r f a c e shows t h e t y p e  but i s i n f e r r e d t o t h e  southwest.  side  Where exposed,  o f u n i t r e p e t i t i o n seen i n t h e lower c o n t a c t ( F i g u r e  Page 26  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia 12),  although f a r more pronounoed . The o r i g i n o f  similar  to  that  relationships  of  the  between  Antler's  adjacent  lower  oontact  structural  this (i.e.  features  surface a thrust  and t h e  is  probably  fault)  ;  the  two s u r f a c e s  are  e s s e n t i a l l y e q u i v a l e n t , and i n d i c a t e t h a t t h e y have shared a common h i s t o r y s i n c e b e f o r e t h e D2 d e f o r m a t i o n . Eureka Q u a r t z i t e This (1971),  unit  was  o r i g i n a l l y included with  phyllite  by K.V.  Campbell  but here i s separated on t h e b a s i s o f g e n e r a l d i s s i m i l a r i t y i n terms o f  composition and t e x t u r e .  No i n d i c a t i o n o f  t h e Crooked Lake area, though and s t r u c t u r a l Jurassic 1981).  the  information  t h e age o f t h i s u n i t i s a v a i l a b l e from concerning  units of similar  p o s i t i o n t o t h e n o r t h suggests t h i s  and t h u s  younger  than  the  q u a r t z i t e may  lithology be  o v e r l y i n g Crooked Lake P h y l l i t e  Lower (Struik  The present author doubts t h a t t h i s i s so, i f indeed i t i s t h e same u n i t ;  it  i s more l i k e l y , c o n s i d e r i n g t h a t i t occurs below t h e Crooked Lake P h y l l i t e , t h a t  it  i s t h e o l d e r o f t h e two. The q u a r t z i t e occurs as a wedge between t h e p h y l l i t e and t h e A n t l e r c r o p p i n g out along t h e n o r t h e a s t s i d e o f Crooked Lake (see P l a t e 4, Campbell limb  of  meters,  (1971) has mapped Eureka S y n c l i n e . though  the u n i t Its  around  thickness  a c c o r d i n g t o K.V.  Campbell  the  Sections4 & 6 ) ;  K.V.  nose and along t h e n o r t h e a s t  w i t h i n t h e map area i s l e s s (1971),  than  20  i t increases i n thickness  toward t h e east. I n outcrop t h e u n i t micaceous Occasionally,  quartzite  i s f i n e t o medium l a y e r e d ,  and g r a p h i t i c  horizons contain  micaceous  quartzite  hornblende, though t h i s  Page 27  f i n e t o medium g r a i n e d , (see  Figure  13).  i s b e l i e v e d t h e r e s u l t of  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia degradation o f garnet i n t h e presence o f b i o t i t e , rocks p o s s i b l y  F i g u r e 13  -  Only  formed i n  a distal  fluvial  magnetite,  or near  Micaceous q u a r t z i t e w i t h p e r v a s i v e folded quartz veining is a {DIR-062, L0C-J94} the  and  quartz.  These  shore beach environment.  p l a t y t e x t u r e ; boudined and common f e a t u r e i n t h i s u n i t  lower c o n t a c t o f t h e q u a r t z i t e was seen exposed (see P l a t e 6 d ) .  The upper c o n t a c t i s b u r i e d beneath abundant t a l u s formed from t h e h i g h l y r e c e s s i v e overlying p h y l l i t e . Crooked Lake P h y l l i t e T h i s u n i t occurs as a r o u g h l y continuous Mountain Group shown i n F i g u r e 6 (R. B. Campbell Tipper (1971) found  et  a l . 1973).  R.B. Campbell  and  belemnites o f p o s s i b l e upper T r i a s s i c age w i t h i n t h i s b e l t i n  t h e Bonaparte map area t o t h e s o u t h ,  a l t h o u g h , as Campbell, R. B. e t a l .  p o i n t out, none o f these f i n d s i s c o n c l u s i v e due The present author  b e l t on t h e west s i d e o f t h e S l i d e  found s e v e r a l  t o ' l a c k o f c r i t i c a l exposures'.  l i t h o l o g i c sub-units Page 28  (1973)  t h a t might have p o s s i b l y  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia yielded  results  i n terms  o f conodont d a t i n g ;  u n f o r t u n a t e l y t h e r e s u l t s from a  sample sent t o t h e G e o l o g i c a l Survey o f Canada were i n c o n c l u s i v e (R.B. Campbell, personal communication, 1982).  F i g u r e 14  -  Black p h y l l i t e and grey p h y l l i t i c s i l t s t o n e w i t h c h a r a c t e r i s t i c s t r o n g f o l i a t i o n and d i s c o n t i n u o u s , transposed l a y e r i n g ; note t i g h t f o l d a t upper r i g h t hand corner {DIR-020, LOC-J88}  Phyllites  orop  out over a good p a r t  map-area and cap t h e f i r s t r i d g e Campbell  (1971)).  between t h e  Antler  northeast  of  the  western p o r t i o n  of  the  o f Crooked Lake ( T a l b o t Ridge o f K. V.  A minimum o f 1800 meters o f present t h i c k n e s s o f p h y l l i t e occurs rocks  n o r t h e a s t o f Crooked Lake.  and t h e  overlying  volcanic/volcaniclastics  to  the  A maximum f i g u r e f o r t h i s u n i t i s not a v a i l a b l e because  i t s upper s u r f a c e cannot be t r a c e d c o n t i n u o u s l y across t h e map-area, though i t  is  b e l i e v e d t o be i n excess o f t h e above-mentioned minimum f i g u r e and p o s s i b l y  in  excess of t h e maximum c i t e d by K.V. Campbell (1971) (around 2600 m e t e r s ) .  Page 29  Structural Ceology of P i t of the Crooked Lake Area, Quesnel Highlands, British Colunbia 8 0 * o f Crooked Lake P h y l l i t e  llite  I phyllitic siltstone  H i g h l y transposed p h y l l i t e w i t h p h y l l i t i c  siltstone  I S * o f Crooked Lake P h y l l i t e  Well-bedded t o c o n t o r t e d l y f o l d e d p h y l l i t i c  siltstone  w i t h p h y l l i t e and o c c a s i o n a l l y a n k e r i t e s c h i s t 5 * o f Crooked Lake P h y l l i t e porphyroblasts of eti, pl«o,iln, or on  sandy linestone  Massive sandstone, p o r p h y r o b l a s t i c p h y l l i t e , s y n e r i s i s - c r a c k e d m e t a - m i c r i t e , sandy limestone  F i g u r e 15 - Summary o f t h e p r i n c i p a l Crooked Lake P h y l l i t e l i t h o l o g i e s  Page 30  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia The  Crooked  micaceous  Lake p h y l l i t e  phyllitic  Sections 2 , 3 , 4 , & 6 ) . the  siltstone  present.  and  chlorite,  muscovite,  ilmenite,  of f i n e l y (refer  quartz,  to  layered, Plate  4,  and g r a p h i t e  are  and t o u r m a l i n e are minor but n e a r l y  The p h y l l i t i c s i l t s t o n e u s u a l l y  and/or * f o l d e d ' l e n s o i d shapes i n a m a t r i x o f phyllitic  entirely  graphitic phyllite  I n most exposures,  major c o n s t i t u e n t s ;  always  i s composed almost  forms d i s c o n t i n u o u s  phyllite  (see F i g u r e  layering 14);  when  s i l t s t o n e predominates t h e u n i t t a k e s on a more r e g u l a r l a y e r e d ( o r  bedded) appearance. bulk t h i s  Figure  15 demonstrates t h e ohange i n  charaoter t y p i c a l of the  u n i t , i n a d d i t i o n t o o u t l i n i n g minor s u b - l i t h o l o g i e s .  and f e l s i c s c h i s t  Thin  quartzite  are very minor l i t h o l o g i e s not mentioned on t h i s diagram.  The response o f t h i s u n i t t o s e v e r a l d e f o r m a t i o n episodes has been extreme (most l i k e l y  because o f i t s u n i f o r m c h a r a c t e r  o r i g i n a l l a y e r i n g t h a t occurred localities,  defines  i n t h e u n i t has been transposed and now,  a highly discontinuous layering  f o l i a t i o n (see F i g u r e 14).  As a consequence,  occurring  package  though  in  it  and f i n e g r a i n e d t e x t u r e ) ;  the p h y l l i t e i s possible,  more  competent h o r i z o n s  no l o n g e r e x i s t as c l e a r l y sense,  i n most  sub-parallel t o a strong  coarser,  i n a very g e n e r a l  any  to  mappable  units,  i d e n t i f y packages of  contrasting l i t h o l o g y within the p h y l l i t e . These There  are  packages i n t h e p h y l l i t e three  different  types  roughly p a r a l l e l that  occur  the  major  - siltstone/sandstone,  p o r p h y r o b l a s t i c l i t h o l o g y , and a l i m e s t o n e / v o l c a n i g e n i c l i t h o l o g y . sandstone package c o n s i s t s o f  light  coloured  q u a r t z a r e n i t e t o arkose c o m p o s i t i o n ; i t i s f i n e chl-ankerite 15).  This  schist  and nodules  contacts. a  The s i l t s t o n e /  s i l t s t o n e and f i n e sandstone of to  medium  l a y e r e d and c o n t a i n s  o f s y n e r e s i s cracked m i c r i t i c l i m e s t o n e ( F i g u r e  l i t h o l o g y i s common on t h e n o r t h e a s t e r n f l a n k o f t h e  Page 31  major h i l l  i n the  Structural Geology of Part of the Crooked Lake Area, quesnel Highlands. British Coluwbia western map area and along t h e t o p porphyroblastic (see  Figures  lithology  42-44);  plagioclase,  graphite,  and  n o r t h e a s t s i d e o f T a l b o t Ridge.  is typified  porphyroblasts  staurolite,  porphyroblasts.  and  by include  and i l m e n i t e ;  chlorite  strong  form the  porphyroblastic  almandine  matrix  for  these  The  northwest o f t h e c u r r e n t map area, b o t h Crooked Lake P h y l l i t e / T a k l a c o n t a c t  in  very  coarse  toward t h e southeast.  One  and Reggie Lakes and a l s o t o t h e  apparent  zone.  i n t e r s p e r s e d w i t h p h y l l i t e s and p h y l l i t i c  Limy  association with the  upper  sediments (<30% c a l c i t e )  are  s i l t s t o n e s t h a t look more green than  u n i t s c o n t a i n very f i n e g r a i n e d a n k - m u s c - c h l - p y - a b - e p - q t z - c c  bio-ep-felsio-act,  more),  to  l i m e s t o n e / v o l o a n i g e n i c package was  examined i n t h e n o r t h e a s t e r n map area below A l e x  The  coarse  quartz,  o f t h i s u n i t e x i s t s i n t h e western map area on t h e n o r t h e r n  slope o f t h e major h i l l ( S t a t i o n J 4 7 ) .  lithology,  chloritoid,  T h i s package crops o u t along much o f t h e steeper southwest slopes  i s o l a t e d occurrence  These  textures  very f i n e t o f i n e muscovite,  o f T a l b o t Ridge; i t s abundance i n c r e a s e s s i g n i f i c a n t l y  grey.  garnet,  The  assemblages r e s p e c t i v e l y .  I n one sample o f  the  and latter  c r y s t a l s o f t a n hornblende appear t o be o f r e l i c t igneous o r i g i n . rhythmic  and  a  nature  fine  of t h i s p h y l l i t e ,  grain size  anaerobic(abundance o f p y r i t e )  suggest  the  abundance o f g r a p h i t e (30% o r  perhaps  a  distal,  restricted  submarine f a n environment as an o r i g i n o f  to  this  u n i t . I f i t i s p o s s i b l e t o r e l a t e t h i s sequence t o t h e o v e r l y i n g  T a k l a Group r o c k s  then t h i s f a n may have formed a d j a c e n t t o a quiescent i s l a n d  arc  receiving  calcareous  material  and v o l c a n i c  detritus  eventually  becoming emergent as an a c t i v e p a r t o f t h e a r c i t s e l f .  The  lower c o n t a c t o f t h e p h y l l i t e was never seen exposed.  from nearby r e g i o n s and  To t h e southwest  A n t l e r rooks u n d e r l i e t h i s u n i t ; t o t h e n o r t h e a s t t h e Eureka Q u a r t z i t e  Page 32  occasionally  wedges  in  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia between t h e oocurs  in  two t o  underlie  the p h y l l i t e .  two d i s t i n c t l o c a l i t i e s .  approximately  300  The upper  oonteot  To t h e west i t i s l a r g e l y covered i n a zone  meters between o u t c r o p s o f Takla and Crooked Lake P h y l l i t e  l i t h o l o g i e s ( F i g u r e 7b) and i s a s s o c i a t e d w i t h t i g h t f o l d i n g development i n t h e T a k l a r o c k s ; of  interdigitations  associated  with  of the p h y l l i t e  of the  and s t r o n g  mylonite  t o t h e east t h e c o n t a c t zone c o n s i s t s o f a s e r i e s  two u n i t s  (see  Plate  a l a r g e amount o f t i g h t f o l d i n g ,  3 and F i g u r e 7c) and i s  again i n a zone about 300 meters  thick.  T h i s c o n t a c t probably o r i g i n a t e d as a primary s u r f a c e o f d e p o s i t i o n ,  later,  l o c a l i z e d displacement o c c u r r i n g along i t .  with  T a k l a Group This Tipper et  unit  is  g i v e n t h e f o r m a l name o f T a k l a  a l . (1979).  Group  r o c k s according t o  I t i s an e x t e n s i v e u n i t i n t h e Quesnel T e r r a i n t o t h e west  and south where i t occurs near Upper T r i a s s i c v o l c a n i c s and sediments o f t h e N i c o l a Group.  The T a k l a Group i s  volcaniclastics  w i t h minor  typified  shale,  by b a s a l t i c  sandstone,  to  andesitic  conglomerate,  volcanics  and  and l i m e s t o n e .  Takla Group r o c k s occur a t t h e e x t r e m i t i e s o f t h e f i e l d area t o t h e southwest and n o r t h e a s t .  K.V. Campbell  (1971) shows r o c k s o f t h i s group c r o p p i n g out i n t h e  c e n t e r o f t h e Eureka S y n c l i n e ;  t o the  unit overlie  Approximately 2300 meters o f Takla and p h y l l i t e i s  the Takla rocks.  north  p h y l l i t e s s i m i l a r t o the underlying  c o n t a i n e d i n t h e Eureka S y n c l i n e above t h e lower p h y l l i t e u n i t . In  the  map  matrix-supported conglomerates, (see  Figures  area  units  observed  hornblende-diorite immature 19a-d).  coarsening upwards;  include  breccias,  f e l d s p a t h i c sandstones,  Within  from west t o  chlorite  phyllites,  clast-supported and  augite  porphyry  diorite flows  t h e T a k l a t h e g e n e r a l c o n f i g u r a t i o n i s one o f east f i n e r s i l t s  Page 33  grade i n t o  coarser  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia F i g u r e 16 - D i s t i n c t i v e l i t h o l o g i e s o f t h e T a k l a Group rocks  F i g u r e 16a -  Foliated chl-hnbd-plag meta-diorite with lensoid/spheroids p l a g - c h l - e p d i r e c t e d along t h e main f o l i a t i o n {DJJM00,LOC-J59}  F i g u r e 16b -  M a t r i x - s u p p o r t e d b r e c c i a w i t h d i o r i t e and massive hnbd c l a s t s elongate i n t h e d i r e c t i o n o f t h e main f o l i a t i o n {DIR-090, LOC-J60}  Page 34  of  structural Geology of Part of the Crooked Lake area. Quesnel Highlands. British Coluwbia  F i g u r e 16c -  C l a s t - s u p p o r t e d conglomerate w i t h d i o r i t e c l a s t s t h a t show a weak e l o n g a t i o n i n t h e plane o f t h e main f o l i a t i o n {DIR-335, L0C-J144}  F i g u r e 16d -  Folded c o n t a c t between v o l c a n i c a r e n i t e and p h y l l i t e ; t h i s p h y l l i t e , more t y p i c a l o f t h e Crooked Lake P h y l l i t e , i s f u l l y contained w i t h i n t h e T a k l a Group r o c k s {DIR-318, L0C-J163}  Page 35  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia sandstones  and  conglomerates.  matrix-supported  in  way  as i n t e r m e d i a t e  e x c u r s i o n i n t o a c i r q u e on t h e n o r t h l i m b  The rock u n i t s a t t h e base  extremely sheared  to  clast-supported volcanics  and  an i s l a n d a r c s e t t i n g .  showed a c o n s i d e r a b l e s i z e body o f f a i r l y rocks.  give  T h i s l i t h o l o g y probably o r i g i n a t e d  associated v o l c a n i c l a s t i c s A short  breooias  of  t h e Eureka  Syncline  f r e s h gabbro t o have i n t r u d e d T a k l a - l i k e  and e x t e n d i n g up t h e s i d e o f Eureka Peak were  and h y d r o t h e r m a l l y v e i n e d .  Some oopper  m i n e r a l i z a t i o n was  a s s o c i a t e d w i t h t h i s v e i n i n g and an a d i t some 20 meters l o n g had been excavated 100 meters f r o m t h e base o f t h e peak.  Page 3 6 ,  Structural 6eology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia STRUCTURE Introduction D e f o r m a t i o n a l episodes have l e f t an obvious i m p r i n t on t h e Crooked Lake rock units.  Some prominent e f f e c t s o f these events i n c l u d e t r a n s p o s i t i o n o f primary  bedding, development o f secondary c o m p o s i t i o n a l l a y e r i n g , s t r o n g mica or f o l i a t i o n s , weak t o s t r o n g l y developed cleavage, and abundant  amphibole  fracturing.  Many o f  these d e f o r m a t i o n a l l y d e r i v e d s u r f a c e s (and some o r i g i n a l ones) e x h i b i t f o l d forms that  are e x c e p t i o n a l l y  features  such  as m y l o n i z a t i o n ,  q u a r t z , and/or only of  common t h r o u g h o u t t h e rock mass as w e l l . linear  e p i d o t e ) , and f a u l t i n g  fabrics,  boudinage,  Additional  veining  (calcite,  are e i t h e r l e s s conspicuous i n n a t u r e or  l o c a l importance.  Analysis  of  these  s t r u c t u r a l h i s t o r y o f an area. the orientations  of  the  structural On t h e  elements  a l l o w s one t o decipher  s c a l e o f a s i n g l e o u t c r o p measurements  the of  v a r i o u s s t r u c t u r a l f e a t u r e s were t a k e n and t h e r e l a t i v e  prominence o f each noted (see S t r u c t u r e Map,  P l a t e 2 ) ; a r e l a t i v e t i m e sequence o f  f e a t u r e s was t h e n determined based on any " c r o s s - c u t t i n g " r e l a t i o n s h i p s t h a t may exist. which  Extending t h i s t y p e o f features  at  one  a n a l y s i s t o t h e g r e a t e r map s c a l e i n v o l v e s locality  relate  to  others  elsewhere.  contemporaneously formed elements may show d i f f e r e n t c h a r a c t e r i s t i c s , o r i e n t a t i o n s , or  may o n l y be l o c a l l y developed, t h e t i m e  deciding Because different  sequences noted a t t h e  l e s s e r s c a l e t o g e t h e r w i t h knowledge o f major c o n t a c t d i s t r i b u t i o n s o f t h e i n t e r p r e t a t i o n o f t h e o v e r a l l geometry ( r e f e r t o Cross  form t h e b a s i s  Sections, Plate 3)  and developmental h i s t o r y i n t h e rock mass as a whole. An i m p o r t a n t assumption t h a t had t o be made t o a l l o w t h e b r i d g i n g o f  small  Page 37  s c a l e o b s e r v a t i o n s t o l a r g e scale  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia interpretations  i s t h a t f e a t u r e s and forms ( e s p e c i a l l y f o l d forms o f  surfaces)  seen i n o u t c r o p have s i m i l a r c o u n t e r p a r t s i n t h e l a r g e r dimension. TABLE I C h a r a c t e r i s t i c Features of the Five Phases o f D e f o r m a t i o n a t C r o o k e d Lake Respective _Events t  05 04  831  03  {02}  02  {01} 6  01 0  General Characteristics Northeast directed faults and fracture sets Gentle to open folds and kink folds (wostly of S2); reclined (Oomain I) and upright plunging (Domain II) symmetry plane of folds, kink band boundary planes hinge line of folds, ext. rot. axis of kinks Open to wediuw folds; upright plunging (Dowain symmetry plane of folds, spaced cleavage hinge line of folds, weak to strong crenulation lineation Open to very tight folds; upright plunging (Domain I) and recuwbent to inclined plunging (Dowain II) symmetry plane of folds, strong nica/awphibole foliation, ueak gneissic layering and/or lensoid development, localized cleavage to spaced cleavage hinge line of folds, strong crenulation lineation, quartz rod lineation, localized awphibole lineation Isoclinal, intrafolial. rootless folds,- nearly cowpletely transposed II to 02 features symmetry plane of folds, foliation or cleavage lying closest to compositional layering and/or with strongly crenulated forw hinge line or folds, weak sulfide sneer lineation Compositional layering, original bedding  Preferred Terwinology S5 F4 S4 L4 ^ S3 L3 F2 S2 12 F1 SI LI SO  DO DO Takla 6p. Antler Fn. Crooked Lake Phyl. Snowshoe fw. Eureka Qztite. t - Event symbols used in the text are with respect to the lower units; symbols shown in curlibrackets refer to an alternate terwinology for a l l but the earliest event (D1).  The r e s u l t o f t h i s a n a l y s i s has l e a d t h e present author Lake d e f o r m a t i o n a l f e a t u r e s i n t o f i v e  d i s t i n c t sets of  Table I above) each o f which can be r e l a t e d Table I o u t l i n e s these f i v e p r e f e r r e d t e r m i n o l o g y used i n  to  a single  episodes, t h e i r  t o group t h e Crooked  s t r u c t u r a l elements event  (see  i n t i m e (D1 t o D5);  characteristic features,  and t h e  t h e f o l l o w i n g d i s c u s s i o n (please note t h a t events  are numbered w i t h r e f e r e n c e t o t h e o l d e s t u n i t s ) .  Page 38  F i g u r e 17 - V a r i a t i o n of minor f o l d forms and t h e i r o r i e n t a t i o n s a c r o s s t h e Crooked Lake area; Domains I and I I are separated by t h e Boss Mtn. A n t i c l i n e ; major c o n t a c t s shown as heavy dashed l i n e s .  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Colunbia Maps and Cross Sections Data (Plate  2).  collected  for  the  map  area  Individual  measurements f o r  is  these measurements  the Structure  P l a t e 1) as p o s s i b l e .  The m a j o r i t y of  r e f e r t o s t r u c t u r a l elements o f a s i n g l e event (shown below t o  has been made t o emphasize t h i s  t h i s reason t h a t an attempt  dominant f a b r i c ( l i g h t dashed l i n e s w i t h o u t double  The f o r m o f these s u r f a c e s was determined by f o l l o w i n g  mapped data and were topography has n o t  Map  i n t h e legend and p l o t t e d as near t o  be D2; see Table I above f o r d e s c r i p t i o n ) and i t i s f o r  arrows).  on  the various possible s t r u c t u r a l features  are i n d i c a t e d by an a r r a y o f symbols as shown t h e s t a t i o n l o c a t i o n s (see Geologic Map,  presented  assumed  to  the  trends  of  be p r o j e c t e d onto a f l a t h o r i z o n t a l plane;  been considered  w i t h respect t o t h i s f e a t u r e !  surfaces represent a penetrative f e a t u r e  Since these  (down t o t h e m i c r o s c o p i c s c a l e ) ,  the  number o f s u r f a c e s and t h e d i s t a n c e s between them are a r b i t r a r y ; t h e choice was made so as t o c l e a r l y show t h e b a s i s f o r m , w h i l e not o b s c u r i n g o t h e r f e a t u r e s on t h e map. Also i n c l u d e d on t h i s map are t r a c e s o f a x i a l s u r f a c e s f o r macroscopic  f o l d forms  w i t h plunges shown, where a p p l i c a b l e . A second i m p o r t a n t  set of features,  i n addition t o the strong  foliation  f a b r i c , i s shown i n F i g u r e 17; across t h e area, w e l l developed f o l d s occur t h a t show a very c l o s e o r i e n t a t i o n r e l a t i o n s h i p w i t h t h e dominant f a b r i c (compare w i t h P l a t e 2).  Examination  of  these  forms  revealed t h a t  the  surface  being f o l d e d  was  c o n s i s t e n t l y a p r i m a r y one, i n t h e case o f t h e upper t h r e e u n i t s (Eureka Q u a r t z i t e , Crooked Lake P h y l l i t e , and T a k l a Group), which makes t h e f o l d i n g event associated w i t h these forms and t h e dominant f o l i a t i o n  the f i r s t  these l i t h o l o g i e s  have  experienced ({D1} or D2 i n Table I ) ; t h e A n t l e r and t h e Snowshoe, on t h e o t h e r hand, show evidence f o r one e a r l i e r f o l d i n g event (D1 i n Table I ) .  Page 40  These r e l a t i o n s h i p s  Structural fieology of Part of the Crooked Lake Area, Quesnel Highlands, British Colunbia are shown i n F i g u r e 17 by s u r f a c e d e s i g n a t i o n s ( e . g . t h e dominant f o l i a t i o n  is  c a l l e d S2 i n a l l u n i t s ) . The s t r u c t u r a l c r o s s s e c t i o n s ( P l a t e 3 ) were d e r i v e d  from features  measurements t h a t c r o s s t h e two s e c t i o n l i n e s shown on P l a t e of  the  sections  interpreted the  is  p a r t i a l l y projected  2.  The  remainder  from t h e S t r u c t u r e Map and p a r t i a l l y  f r o m known f a c t s concerning t h e c h a r a c t e r o f d e f o r m a t i o n a l  outcrop  scale.  and  An i m p o r t a n t p o i n t t o note concerning these  forms  sections i s  at the  r e l a t i o n s h i p between t h e two f o l d forms o u t l i n e d by t h e major o o n t a c t s . O r i g i n a l l y , the  a n t i f o r m / s y n f o r m p a i r ( h e r e designated t h e B a s s e t t / S t a r k p a i r )  was  believed  1971). forms  to  be p a r a s i t i c  The present to  author  t h e west  Bassett/Stark  pair  (refer  t o t h e Boss Mountain A n t i c l i n e  h o l d s t h a t t h i s cannot be t h e case. t o Figure  (upright-plunging)  17) w i t h o r i e n t a t i o n s are always found  p e r v a s i v e f o l i a t i o n , S2, i n an a x i a l p l a n a r (see P l a t e 2 ) i s  clearly  not f o l d e d  an a x i a l p l a n a r r e l a t i o n s h i p t o them, as  r e l a t i o n s h i p t o t h e main  t o those  foliation,  recumbent t o i n c l i n e d - p l u n g i n g p o s i t i o n , g i v e s credence forms a s s o c i a t e d t h e  Bassett/Stark  pair  All  minor f o l d the  associated w i t h  the  set  of  p a i r , but  surfaces lies in  The f a c t t h a t f o l d forms t o t h e  east (see F i g u r e 17) w i t h s i m i l a r c h a r a c t e r i s t i c s same a x i a l p l a n a r  (K.V. Campbell  to  the Bassett/Stark  well.  t h e west  similar  r e l a t i o n s h i p . This  about  to  i n t h e west  have t h e  S2, and here l i e i n a to  the  suggestion  that  are a c t u a l l y f o l d e d over t h e Boss  Mountain A n t i c l i n e (which i s , t h u s , i n t e r p r e t e d as a 03 f e a t u r e ) . Domains As t h e S t r u c t u r e follows  Map and Cross S e c t i o n s ,  P l a t e s 1 & 2, show.  Crooked Lake  t h e t r a c e o f t h e a x i a l s u r f a c e o f t h e D3 Boss Mountain A n t i c l i n e (K.V.  Campbell 1971), and a c c o r d i n g l y  can be used as t h e d i v i d i n g  Page 41  line  between two  Structural Geology of Part of the Crooked Lake Area^ugsnejJjighlMds,  British CoTmhi,  Domain I I - east limb o f Boss Mtn. A n t i c l i n e  Domain I - west limb of Boss Mtn. A n t i c l i n e  F i g u r e 18a - Contour p l o t s o f poles t o S2 f o l i a t i o n s from Domains I & I I (contours represent 0,5,10,15,20% of p o i n t s per 1% stereonet area) Page  42  Structural geology of Part of the Crooked Lake Area, Quesnel Highlands, B r i t i s h Coluwbia N  Domain II  N  \ o BP  'AN' SN  Boss Mountain Anticline  • • •  Scali •  1  liloaetsrs  Domain  F i g u r e 18b - Contour p l o t s o f 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 (bedding?) and envelopping s u r f a c e s o f D2 f o l d s ( c o n t o u r s are 0,5, &10% per 1% area) Page 43  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia d i s t i n c t groups o f measurements, i . e. t h e west and east l i m b s o f t h i s f e a t u r e .  The  t o t a l data contour p l o t s f o r p o l e s t o t h e S2 f o l i a t i o n shown i n F i g u r e 18a (and t o a lesser  extent  the  contour  plots  of  compositional  layering  in  Figure  18b)  i l l u s t r a t e t h a t t h e r e are s i g n i f i c a n t d i f f e r e n c e s between these two r e g i o n s ( t o t h e southwest t h e S2 f o l i a t i o n 110°/50 NE). Q  planes average 1 6 5 ° / v e r t i c a l  and t o t h e  northeast  T h i s d i f f e r e n c e , t h e n , forms t h e b a s i s f o r a breakdown o f t h e Crooked  Lake data i n t o two main Domains, I , t o t h e southwest and, I I , t o t h e n o r t h e a s t (see F i g u r e 17). The  following  is  a d i s o u s s i o n o f each o f  t h e y were observed as minor f e a t u r e s i n t h e large-scale  the  f i e l d and  phases reflected  o f d e f o r m a t i o n as in  the  overall  m a p - p a t t e r n . C o n s i d e r a t i o n has been g i v e n as t o how each phase has  e f f e c t e d t h e f i v e d i f f e r e n t u n i t s , t h e i r c o n t a c t s , and e a r l i e r s u r f a c e s i n each o f t h e two Domains. mesoscopic f i e l d  T h i n s e c t i o n s were examined t o c o r r o b o r a t e , o b s e r v a t i o n s and t o  where p o s s i b l e ,  provide information r e l a t i n g mineral  growth  and d e f o r m a t i o n h i s t o r i e s . Phase One T h i s e a r l y phase i s  not r e p r e s e n t e d  t o t a l l y throughout the  s t r u c t u r a l p i l e . D i r e c t evidence o f a c l e a r pre-D2 stage t h e present author Campbell (1971,  only  in  of  lithologic/  f o l d i n g was found by  t h e A n t l e r Formation (see F i g u r e 19), though K.V.  p.173) shows good examples o f r o o t l e s s ,  intrafolial  isoclines  i n v o l v e d i n what appear t o be medium, phase two f o l d s i n Snowshoe ( i n t h e f o l l o w i n g d i s c u s s i o n , t h e terms open, medium, t i g h t ,  and i s o c l i n a l r e f e r t o t h e  interlimb  [ d i h e d r a l ] angles: 180-120°, 120-60°, 6 0 - 2 0 ° , 2 0 - 0 ° , r e s p e c t i v e l y ) . I n t h e upper three  u n i t s evidence f o r t h i s phase does not e x i s t ;  Page 44  t h i s would i m p l y t h a t  Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia  F i g u r e 20  -  I s o c l i n a l f o l d c l o s u r e i n v o l v i n g c o m p o s i t i o n a l l a y e r i n g o f qtz-musc marble and p l a g - m u s c - b i o - q t z s c h i s t {DIR-330, L0C-J74}  Page 45  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. B r i t i s h Coluwbia  a - Equal-area net p l o t o f poles t o a x i a l s u r f a c e s o f D1 f o l d s f r o m both Domains  Equal-area net p l o t o f D1 f o l d hinges f r o m both Domains t  = t(mm)/to(mm)  c - t - a l p h a p l o t o f D1 F o l d Forms Snowshoe J72, J74, J74b, A n t l e r RZ6; (see Appendix C f o r e x p l a n a t i o n of f o l d form c u r v e s ) 0  10 20 30 40 50 60 70 80 90 Alpha = a°  F i g u r e 21 - C h a r a c t e r i s t i c s o f D1 minor f o l d forms Page 46  Structural Geology of Part of the crooked Lake area. Quesnel Highlands. British Coluwbia d e p o s i t i o n ( o r emplacement) o f t h e s e u n i t s p o s t - d a t e phase one d e f o r m a t i o n o f t h e lower two u n i t s . The  most t y p i c a l forms r e p r e s e n t i n g D1 i n t h e Snowshoe  i n t r a f o l i a l i s o c l i n a l f o l d s of compositional and P l a t e 6 f ) ;  most  often  these forms  are  l a y e r i n g and/or very  and A n t l e r  bedding  small, rootless  are  ( F i g u r e 20  features  (they  t a k e up l e s s t h a n 1 or 2 sq. dm.) embedded i n a h i g h l y f o l i a t e d and c o m p o s i t i o n a l l y streaked matrix.  An S1 mica f o l i a t i o n i s best  t h i n s e c t i o n s o f Snowshoe r o c k s f r o m Domain I feature i s  certain  o n l y when  seen as a transposed f e a t u r e i n  (see F i g u r e M1).  I n the f i e l d t h i s  i n t e r f e r e n c e o f D1 f e a t u r e s w i t h D2 f o l d i n g can be  demonstrated (most e a s i l y seen when D2 f o l d s have a medium f o r m and S2 occurs as a prominent spaced c l e a v a g e ) . F i g u r e 21 summarizes Snowshoe and A n t l e r .  t h e o r i e n t a t i o n and f o r m  data f o r  D1 f o l d s f r o m t h e  The r a r i t y o f such forms i n t h e area mapped i s r e f l e c t e d i n  t h e very s m a l l number o f data p o i n t s ; n e v e r t h e l e s s , t h e o r i e n t a t i o n o f  these  folds  ( F i g u r e 21a, b) l i e s w i t h i n t h e range o f ) D2 f o l d data ( F i g u r e 25 ) which r e f l e c t s t h e near complete t r a n s p o s i t i o n o f D1 s u r f a o e s t h a t was observed i n t h e f i e l d . t-alpha  The  p l o t ( t e c h n i q u e f r o m Ramsay, 1967; see Appendix C f o r e x p l a n a t i o n and d a t a )  o f D1 f o l d forms ( F i g u r e 21c) shows a d i s t r i b u t i o n o f p o i n t s t h a t suggests Class 2 t o Class 3 t y p e f o l d s w i t h very low i n t e r l i m b angles (« 1 5 ° ) . Interference  forms  F i g u r e 19 and P l a t e 6h; 19  and P l a t e  medium f o l d s .  6h  between D1 and D2 observed i n t h e map area are shown i n  forms between D1 and o t h e r  show D1 f o l d s  events  of compositional  were n o t seen.  layering  Figure  wrapped about D2  The r a r i t y o f such forms i s b e l i e v e d t h e r e s u l t o f t h e s t r e n g t h and  pervasiveness o f t h e D2 d e f o r m a t i o n .  Page 47  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Large has  scale  had on t h e  interfingering  features rock  t h a t might o u t l i n e t h e  units  at  Crooked Lake  o f t h e Snouishoe/Antler c o n t a c t  effeot  are  t h a t t h i s deformation  not  i n Domain  II  definitive.  Tight  n e a r l y always shows  t h e same c h a r a c t e r i s t i c s as t h e s u r f a c e above ( t h e E u r e k a / A n t l e r c o n t a c t ) , so i t i s thought t o be p r i m a r i l y a D2 e f f e c t ; u n f o r t u n a t e l y of  these  s u r f a c e s were  large  enough p r o f i l e s e c t i o n s  never observed so t h e present author can o f f e r  confirmation or denial of possible m u l t i p l e f o l d i n g of t h i s surface. m y l o n i t e w i t h i n t h e Snowshoe were a r e s u l t of  always  seen i n v o l v e d  no  Zones o f  i n D2 f o l d i n g and may be  D1 d e f o r m a t i o n a n d / o r some p e r i o d o f deep l e v e l t h r u s t f a u l t i n g .  Very  d e t a i l e d mapping o f t h e Snowshoe, w i t h c a r e f u l a t t e n t i o n p a i d t o s t r a t i g r a p h y might be able t o d i s c e r n t h e complex n a t u r e o f these e a r l i e r f e a t u r e s ; i f i t i s reasonable to relate  t h e f i r s t phase minor forms seen a t Crooked Lake w i t h ones f r o m areas t o  t h e east and south (Ghent e t 1982),  al.  1977;  Murphy and Journey 1982; P e l l and Simony  such mapping should have a broad a r e a l e x t e n t . Phase Two E f f e c t s o f t h e second d e f o r m a t i o n vary mostly as a r e s u l t o f  variation.  T h i s change  produces s l i g h t l y d i f f e r e n t s t r u c t u r a l f e a t u r e s i n  major u n i t and between s u b u n i t s where r h e o l o g i c h e t e r o g e n e i t y general  sense a l l major u n i t s  so a l l can be expected event;  display  t o show  some degree  of  i s important.  each In  a  i n t e r n a l h e t e r o g e n e i t y and  t h e f u l l range o f elements p o s s i b l e f o r t h e D2  t h e d i f f e r e n c e between major u n i t s observed was t h u s one o f  abundance  lithologic  of the various features.  By f a r ,  relative  t h e Crooked Lake P h y l l i t e shows t h e  most v a r i e d s e t o f 02 f e a t u r e s w h i l e t h e Eureka Q u a r t z i t e and Snowshoe show t h e least (the Antler  Formation and t h e Takla Group l i e somewhere midway).  Page 48  structural ecology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia The  lextural  feature  associated with the  f r e q u e n t l y i n a l l rock u n i t s i s a prominent mica attendant compositional  layering.  D2  event  t h a t occurs  o r amphibole  foliation  most and  T h i s f o l i a t i o n c h a r a c t e r i s t i c a l l y has a 'wavy'  N  _L  F i g u r e 22  -  Equal area n e t p l o t o f poles t o p l a n a r measurements from a s i n g l e S2 f o l i a t i o n s u r f a c e a t RZ11 i n t h e Snowshoe; t h i s v a r i a b i l i t y i s c h a r a c t e r i s t i c o f S2 f o l i a t i o n s u r f a c e s across t h e area  form ( F i g u r e 22 shows an equal area net p l o t o f poles t o p l a n a r measurements f r o m a s i n g l e f o l i a t i o n s u r f a c e ) due p r i m a r i l y t o i n t e r f e r e n c e o f D4 f o l d i n g (see Phase Four below).  The  p o s i t i o n near p a r a l l e l distance  (on t h e o r d e r  compositional to of  it;  l a y e r i n g accompanies t h i s  t h i s layering  may be m i l d l y continuous f o r a s h o r t  decimeters t o a meter a t most),  Page 4Q  foliation in a  but i s  streaky  and  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. B r i t i s h Coluwbia  F i g u r e 23a -  U p r i g h t open t o medium f o l d s i n i n t e r l a y e r e d p h y l l i t e / p h y l l i t i c s i l t s t o n e ; t h e s i g m o i d a l shape o f segments o f s i l t s t o n e u n i t between cleavage planes i n d i c a t e shear along those planes; u n i t s d r a s t i c a l l y t h i n toward l e f t {DIR-340, L0C-J40}  F i g u r e 23b -  U p r i g h t t i g h t s i m i l a r f o l d t r u n c a t e d on t h e r i g h t f o l i a t e d p h y l l i t e {DIR-350, L0C-J36}  Page 50  against  planar  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. B r i t i s h Coluwbia  F i g u r e 24 - t - a l p h a p l o t s o f D2 f o l d s t  t  = t(mm)/to(mm)  1.50 i  0  1.50  1  I  10 20 30 40 50 60 70 80 90 Alpha = a  0  b - Medium f o l d s a t J41, J5, RZ5, RZ6,RZ7,RZ10  (curves e x p l a i n e d i n Appendix C)  0  10 20 30 40 50 60 70 80 90 A l p h a = a°  0  a - Open f o l d s a t J40, J89, J57, RZ8;  t 1.50 i  = t(mm)/to(mm)  = t(mm)/to(mm)  t 1.50 i  1  0  10 20 30 40 50 60 70 80 90  = t(mm)/to(mm) 1  10 20 30 40 50 60 70 80 90 A l p h a = a°  Alpha = a° c - T i g h t f o l d s f r o m J26, J117, J36, J26b, J41b  d - B a s s e t t / S t a r k p a i r t a k e n from P l a t e 3, Cross S e c t i o n 1  Page 51  S t r u c t u r a l Geology of P a r t of the Crooked Lake Area, Q u e s n e l j | i o h l a n d s , B r i t i s h C o l u n b i a  w  b - P o l e s t o S2 a x i a l p l a n e s o f m i n o r f o l d f o r m s f r o m Domain  a - P o l e s t o S2 a x i a l p l a n e s o f  X-  m i n o r f o l d f o r m s f r o m Domain ( 0 & 10% p e r 1% a r e a c o n t o u r s  I  (0. 1 0 , 2 0 , 3 0 % per 1% a r e a c o n t o u r s  II  \  shown)/  shown)  /~ >r  n  r" 1  1  -7  V  TK  /•••.^•: : x : :  I, : :P: r :  V  X  0  1  lilMeters d - L 2 , f o l d h i n g e s f r o m Domain ( 0 & 10% p e r 1% a r e a c o n t o u r s / ./  c - L2 f o l d h i n g e s f r o m Domain ( 0 , 5 , 1 0 , 1 5 % p e r 1% a r e a c o n t o u r s  F i g u r e 25 - D2 f o l d e l e m e n t s f r o m Domains I & I I shown as c o n t o u r  Page 52L  II  shown)  \  I shown)  plots  \  Structural ecology of Part of the crooked Like Area, Quesnel Highlands. British Colunbia  F i g u r e 26b -  Recumbent t i g h t f o l d s i n p h y l l i t i c s i l t s t o n e ; note curved f o l d hinges <• s h e a t h - l i k e ' f o l d f o r m ) {DIR-345,L0C-J171}  Page 53  structural 6eology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia discontinuous  over  all.  Lensoid  f o r m a t i o n f r o m boudinage o f  s u b u n i t s accompanies or makes up a s u b s t a n t i a l  more  oompetent  p o r t i o n of t h i s l a y e r i n g ;  t h e shape  o f these bodies can range f r o m d i s c s t o s m a l l i s o l a t e d f o l d hinges ( P l a t e 6 i ) continuous, 12 meters  though h i g h l y  a t t e n u a t e d f o l d forms (one seen c o u l d be f o l l o w e d f o r  and had < 2 c e n t i m e t e r t h i c k  repetitive  enough  plane l i e s p a r a l l e l This  to  to  develop  tight  limbs).  fold  Occasionally  forms ( F i g u r e s  the layering  23b, 26b)  whose  is  axial  t o t h e main f o l i a t i o n .  t y p i c a l f a b r i c ( p r o p o r t i o n s are o u t l i n e d i n F i g u r e 14) forms a m a t r i x  f o r volumetric  r e g i o n s where l i t h o l o g y i s n o t as homogeneous. Here, l a y e r i n g tends  t o be more continuous t h e dominant  D2  (on t h e  structural  o r d e r o f meters) and a s t r o n g cleavage occurs element  (see F i g u r e 2 3 a ) .  The  d i f f e r e n t t y p e s o f f o l d e d forms a l l w i t h a x i a l planes p a r a l l e l cleavage (see F i g u r e s  23a & 2 6 a ) .  as  l a y e r i n g shows t o the S2({S1})  The s i z e o f these f o l d e d zones was d i f f i o u l t t o  determine because o f l a c k o f s u f f i c i e n t exposures where t h e y occur,  b u t t h e i r shape  i s most  to  oertainly  lens-like  - t h e l o n g dimension runs p a r a l l e l  and S2 f o l i a t i o n i n t h e m a t r i x . their  Groups o f these  l o n g dimension i s s h o r t e r t h a n  appear t o be d i s t r i b u t e d the Bassett/Stark  t h e average  zones ( i f  S2 cleavage  we can assume t h a t  d i s t a n o e between exposures)  p a r a l l e l t o t h e major c o n t a c t s , except i n t h e v i c i n i t y o f  antiform/synform pair  (where t h e y are near p e r p e n d i c u l a r  to  contacts). 02  f o l d forms have been grouped i n t o t h r e e t y p e s o f  and open corresponding t o t h e most s i g n i f i c a n t l y d i f f e r e n t observed.  F i g u r e 24 shows t - a l p h a  plots  forms: t i g h t ,  medium,  l e v e l s of heterogeneity  o f each of these forms.  The t i g h t forms  (24c) f a l l between t h e Class 2 t o Class 3 c a t e g o r i e s , t h e i n t e r m e d i a t e forms (24b) are Class 1 t o Class 2 f o l d s ,  and t h e open f o l d s (24a) f a l l i n t o Class 1.  Page 54  The  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Coluwbia former  two  d i f f e r e s s e n t i a l l y by t h e amount  attenuation; isoclinal, relatively causes  i n comparison t o D1  folds,  of  f o l d olosure  the t i g h t  and degree o f l i m b  f o l d s are  not  so c l e a r l y  though t h e y do show q u i t e s i m i l a r values f o r l i m b a t t e n u a t i o n . wide spacing  more  physical  thinning (Figure 23a);  that  occurs between S2 cleavage s u r f a c e s o f open  disruption  of  the  layers  than  The folds  any a p p r e c i a b l e  limb  as a consequence t h e s e f o l d s show r e l a t i v e l y c o n s t a n t l i m b  thickness. A  pictorial  demonstration  of  the  contrasting  orientations  d e f o r m a t i o n a l elements i s presented i n F i g u r e 17 ( a l s o see F i g u r e s 23 & 2 6 ) . each o f  of  D2  Within  t h e two Domains, S2 f e a t u r e s (here r e p r e s e n t e d by a x i a l planes o f D2 f o l d s )  show minor v a r i a b i l i t y f r o m a v e r t i c a l o r i e n t a t i o n i n Domain I northeast  dipping  orientation  planes f r o m Domain I vertical position;  (Figure  the  spread  i n Domain I I . 25a)  indicate  d i p p i n g planes  with  Contour p l o t s o f poles t o these an  approximate maximum  o f t h i s data suggests t h a t  f r o m steep east d i p p i n g planes w i t h s t r i k e s f r o m s t r i k e s from  and f r o m a shallow  in  a  these planes a l t e r n a t e  110°-135° b e a r i n g t o steep west  135°-170° b e a r i n g .  F i g u r e 25c shows t h e plunge  o f these f o l d s t o have an average o r i e n t a t i o n o f 330°-345° t r e n d , p l u n g i n g 4 5 ° - 5 0 ° . The Domain I I p l o t  ( F i g u r e 25b) shows a more c o n s t a n t o r i e n t a t i o n f o r S2,  i.e.  80°-110° s t r i k e and d i p p i n g 4 5 ° - 5 0 ° t o t h e n o r t h and f o l d s plunge 30°-40°and t r e n d 335°-345°. D2 s t r u c t u r a l elements have been v i s u a l l y e f f e c t e d by two o f t h e l a t e r t h r e e deformations ( i . e . is  D3 and D4).  I n Domain I , a combination o f t h e D3 and D4 events  b e l i e v e d t o cause t h e wavy f o r m o f S2 shown i n F i g u r e s 22 & 25.  strong  sub-horizontal  crenulations  on  S2,  while  D4  is  D3 causes t h e  responsible  n e a r - v e r t i c a l c r e n u l a t i o n s . T h i s s u r f a c e i s seen i n o u t c r o p t o be open t o  Page 55  for  medium  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia f l e x u r a l l y f o l d e d by D4 ( P l a t e 6 1 ) ; F i g u r e 31a demonstrates how poles t o S2 spread out along a g r e a t c i r c l e whose p o l e approximates t h e placement o f L4 f o l d hinges. Evidence of 03 f o l d s of S2 i n Domain I was l a c k i n g .  Domain I I c o n t a i n s e x c e l l e n t  examples o f D3 r e f o l d i n g o f D2 forms ( F i g u r e 27 & P l a t e 6 j ) .  F i g u r e 27  -  F i g u r e 31b, c show  I n t e r f e r e n c e o f recumbent t i g h t phase two f o l d s w i t h u p r i g h t phase t h r e e f o l d s ( t o l e f t near q u a r t z v e i n ) {DIR-317, L0C-J117}  combined data p l o t s d e p i c t i n g t h i s r e l a t i o n s h i p ; t h e data f o r F i g u r e 31b was taken along  t h e e x t e n t o f t h e upper and lower  Antler  contacts t h a t  were  often  seen  i n v o l v e d i n phase t h r e e  f o l d i n g ; t h e data f o r F i g u r e 31c came f r o m t h e area around  Reggie and Alex l a k e s .  K i n k i n g and very m i l d f o l d i n g of S2 ( F i g u r e 32)  is  a t t r i b u t e d t o the D4 e v e n t s e f f e c t i n Domain I I . 1  On t h e  macroscopic  scale the Basset/Stark  S e c t i o n 1, P l a t e 3 ) and t h e r e p e t i t i o n  fold  pair  along t h e A n t l e r  i n Domain I (Cross  ( F i g u r e s 9b,  12) and  P h y l l i t e / T a k l a (Cross S e c t i o n 2, P l a t e 3 and F i g u r e 7c) c o n t a c t s i n Domain I I are b e l i e v e d t o be  r e p r e s e n t a t i v e phase two s t r u c t u r e s .  Formation,  it  as  appears i n t h e Cross S e c t i o n 1 ( P l a t e  Page 56  The form o f t h e A n t l e r 3),  i s shown  as  a  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. B r i t i s h Coluwbia t-alpha  plot  scale t i g h t  in  F i g u r e 24d;  this  data agrees reasonably w e l l w i t h t h e s m a l l e r  t o medium D2 f o l d forms ( F i g u r e 2 4 b ) . Phase Three  A number o f f e a t u r e s r e p r e s e n t t h e t h i r d phase o f f o l d i n g i n t h e Lake rock u n i t s .  The most obvious e f f e c t i s  change t h e i r o r i e n t a t i o n s f r o m one s i d e been i n t e r p r e t e d as f o l d i n g  F i g u r e 28  -  Anticline.  of  t h a t phase two s t r u c t u r e s d r a s t i c a l l y  of Crooked Lake t o t h e o t h e r ;  t h i s has  D2 elements over t h e macroscopic Boss Mountain  U p r i g h t open D3 f o l d i n g o f A n t l e r / E u r e k a c o n t a c t {DIR-325, L0C-J102) On t h e s m a l l e r s c a l e , exposed c o n t a c t s across Domain I I  u p r i g h t f o l d form ( F i g u r e 28) and phase two elements forms) are a c t u a l l y 6j).  Crooked  o f t e n show an  (S2 f o l i a t i o n and t i g h t f o l d  seen f o l d e d by t h i s same t y p e o f f o l d form ( F i g u r e 27 and P l a t e  I n both domains, s u b - h o r i z o n t a l t o s h a l l o w - p l u n g i n g c r e n u l a t i o n s on S2 are  u b i q u i t o u s and o c c a s i o n a l l y a s s o c i a t e d w i t h a near u p r i g h t spaced cleavage (S3).  Page 57  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Coluwbia The 30c.  a  t - a l p h a p l o t i n Figure  The spread o f data i n t h i s p l o t suggests t h a t D3 f o l d s are Class 1c f o l d s a t  most. D3  basio f o r m o f D3 f o l d s i s shown i n terms o f  P l a t e 6k demonstrates t h e g r a d u a l change i n f o r m t h a t i s c h a r a c t e r i s t i c  folding.  This  change  in  form  p e r p e n d i c u l a r t o t h e major c o n t a c t s .  was  observed t o  occur  in  a  of  direction  Cross S e c t i o n 2 demonstrates t h i s f o r m change  w i t h a p a r a s i t i c f o l d t h a t crops o u t i n t h e v i c i n i t y o f Reggie and A l e x l a k e s . O r i e n t a t i o n o f i m p o r t a n t D3 f e a t u r e s i s d e p i c t e d i n F i g u r e 29a, b and 30a. distinctive  spaced cleavage  both Domains I & I I  is  the  (Figure 29).  most  common  03 p l a n a r f o r m found through  Comparison o f these s u r f a c e s w i t h t h e  planes of D3 f o l d forms f r o m Domain I I steeply-northeast dipping surfaces  that  A  axial  ( F i g u r e 30a) show them t o be moderate t o s t r i k e t o t h e northwest.  Linear f a b r i c s  a s s o c i a t e d w i t h D3 ( F i g u r e 29 c, d & 30b) vary i n a r e g u l a r f a s h i o n across t h e two Domains f r o m NNw w i t h a moderate plunge i n Domain I t o Nil) w i t h a s u b - h o r i z o n t a l plunge along t h e A n t l e r c o n t a c t s ( a l s o see F i g u r e 3 1 b , c ) t o NW w i t h a moderate plunge near Reggie and A l e x l a k e s . The  i n t e r f e r e n c e o f D3 elements w i t h younger events i s  d e a r , e s p e c i a l l y from o u t o r o p a n a l y s i s . o f D3  linear  not  immediately  I t i s p o s s i b l e t h a t t h e change i n plunge  forms (compare F i g u r e s 31b and 31o) may be a D4 e f f e c t . The form  suggested f o r t h e Boss Mountain a n t i c l i n a l a x i a l s u r f a c e shown i n P l a t e 2 i s meant t o show t h e same k i n d o f D4 warping seen t h r o u g h o u t t h e  dominant D2 f a b r i c across  t h e area. Besides  the  Boss  Mountain  Anticline,  f o r m observed was t h e f o l d f o r m shown i n  the  only  o t h e r macroscopic  Cross S e c t i o n 2 ( P l a t e 3 ) .  o r i e n t a t i o n t h a t occurs t o numerous D2 f e a t u r e s (S2 f o l i a t i o n s , area i s g r a d u a l  and d e l i b e r a t e .  03  The change o f  f o l d forms) i n t h i s  Refolded f o l d forms and u p r i g h t f o l d s o f c o n t a c t s  o f a number o f i n t e r n a l h o r i z o n s are common i n t h i s Page 58  area  ( F i g u r e 30b).  S t r u c t u r a l G e o l o g y o f P a r t o f the C r o o k e d Lake A i e a , Q u e s n e l H i g h l a n d s .  British  Colunbia  A b - P o l e s t o S3 c l e a v a g e s V  a - P o l e s t o S3 c l e a v a g e s  1 ^  f r o m Domain I  ' -- ^. k  ( 0 & 10% p e r 1% a r e a  contours  k  f r o m Oomain I I ( 0 , 5 , 1 0 . 1 5 % p e r 1% a r e a c o n t o u r s  shown)  shown)  .~-\_  1 ;3 .y  / I  1  1/ Anticline  1  o  1  Kileneters  4  d - L3 c r e n u l a t i o n l i n e a t i o n s  ^ ' t w ^ X - ' . •: •:(  f r o m Domain I I ( 0 , 10, 20, 30, 40%,pWpV\'.'-'A  V.  per  /  "V• •. -\  ..'  c - L3 c r e n u l a t i o n ' ' om Domain I  F i g u r e 2 9 - D3 c l e a v a g e s and c r e n u l a t i o n s contour Page 5 9  ^  lineations  ( 0 , 5 , 1 0 % p e r 1% a r e a  contours  C:  1% a r e a c o n t o u r s shown)  shown)  f r o m Domains I & I I shown as plots •ip;/  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia  a - Contour p l o t o f p o l e s t o a x i a l planes o f 03 f o l d forms from Domain I I (0,5,10% per 1% area contours shown)  mm b - Contour p l o t to D3 f o l d forms (0,5,10,15,20% contours  of f o l d hinges from Domain I I per 1% area shown)  t = t(mm)/to(mm) 1.50 1.40 1.30 1.20 h 1.10 1.00 .90 h .80 .70 no &s,a .60 • ^ . 5 0 I.40 .30 . 2 0 (.10 J . 00  c - T-alpha p l o t o f 03 F o l d Forms C L . P h y l l i t e J98, J104, J117; curves explained i n Appendix C  DO  I  0 10 20 30 40 50 60 70 80 90 Alpha = a"  F i g u r e 30 - C h a r a c t e r i s t i c s  of D3 minor f o l d forms Page 6 0  Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia  +  S4 A x i a l Planes  ffl S2 F o l i a t i o n  * •  F i g u r e 31a - Combined data p l o t ( e q u a l area) t o show t y p i c a l spread o f p o l e s t o S2 f o l i a t i o n and a x i a l planes and L2 f o l d hinges i n r e l a t i o n t o D4 f e a t u r e s f r o m Domain I (D1 f e a t u r e s  included)  Page 61  o  • •  S2 A x i a l Planes S1 A x i a l Planes L4 F o l d Hinges L2 F o l d Hinges L1 F o l d Hinges  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. B r i t i s h Colunbia  S2 F o l i a t i o n 52 A x i a l Planes 53 A x i a l Planes F i g u r e 31b - Combined d a t a p l o t ( e q u a l area) showing r e l a t i o n s h i p between D2 and D3 f e a t u r e s i n Domain I I along upper and lower A n t l e r c o n t a c t s  (J85—>J114)  Page 62  L2 F o l d Hinges L3 F o l d Hinges  ffl S2 F o l i a t i o n  • •  F i g u r e 31c - Combined data p l o t ( e q u a l a r e a ) showing r e l a t i o n s h i p between D2 and D3 f e a t u r e s i n Domain I I i n t h e n o r t h e a s t e r n - m o s t p a r t o f t h e map area (J142—>J171)  Page 63  S2 A x i a l Planes S3 A x i a l Planes L2 F o l d Hinges  •  L3 F o l d Hinges  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, B r i t i s h Coluwbia  F i g u r e 32a -  Double kink o f main f o l i a t i o n (S2) i n Crooked Lake P h y l l i t e ; note change with depth t o very open f o l d i n g {DIR-060, L0C-J77}  F i g u r e 32b -  C l o c k w i s e kink i n Crooked Lake P h y l l i t e ; zone i s 3-4 cm wide and grades i n t o very open f o l d i n g below {DIR-005, LOC-J84}  Page 64  —  t  u  r  a  l  G e  ° l ° a y o f P a r t o f t h e Crooked Lake Area, Quesnel H i g h l a n d s , B r i t i s h Columbia  b - S4 k i n k band b o u n d r y p l a n e s a - P o l e s t o S4 a x i a l p l a n e s  of  m i n o r f o l d f o r m s f r o m Domain  m  1  \  ( 0 , 1 0 , 2 0 * per  U  area contours  I  f r o m Domain I I  ^  (0 & 5 0 * p e r 1%  area contours  shown)  shown)  mm*  4  TK  Anticline  i  o Kileactars  d - L4 k i n k axes f r o m Domain (0,30% p e r /  ?  •X  \)  /  c - L4 f o l d h i n g e s f r o m Domain ( 0 & 10% p e r n  area contours  F i g u r e 33 - D4 f o l d e l e m e n t s f r o m Domains I & I I  Page 65  1% a r e a c o n t o u r s  II  shown)/  /  I  shown)  shown as c o n t o u r  i  plots  f  t  i  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, B r i t i s h Coluwbia F i g u r e 34 - S t r e s s d e t e r m i n a t i o n of D4 episode f r o m deformed S2 f o l i a t i o n s Carter & Raleigh,  (from  1969)  Haximin conpressive  m stress  • S2 Foliation Pole of deforned plane  (5> Deforned S2 Foliation External rotation toward naxlHun conpressive stress Pole of original plane  * Kink Band Boundries  t7rlaxinun  Conpressive  Stress Deternination  According to experimental data (left) when surfaces are in a position of high shear, they  Hill  deforn within restricted zones (kink  bands); as shown, poles of deforned planes should rotate toward the naxinun conpressive stress, (here assumed to be 90° fron pole  of kink band boundry). Shaded area (above) indicates D4 stress orientation. Page 66  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia Phase Four The minor forms r e s u l t i n g f r o m t h e f o u r t h d e f o r m a t i o n d i f f e r l a r g e l y f u n c t i o n o f t h e f a b r i c w i t h i n each o f t h e domains. I n f o l i a t i o n i s close t o  Domain I ,  as  a  where t h e S2  v e r t i c a l , phase f o u r f o l d s are buckle f o l d s ( o f t e n o c c u r r i n g  as conjugate p a i r s ) w i t h  steep hinges ( 5 5 ° - 6 5 ° t o t h e NW) and near v e r t i c a l a x i a l  planes s t r i k i n g ENE ( F i g u r e 33a, c & P l a t e 6 1 ) ; these f l e x u r a l d i e out i n amplitude w i t h i n a conjugate k i n k i n g o f t h e  few meters  a t most.  style  folds quickly  To t h e n o r t h e a s t i n Domain I I ,  S2 f o l i a t i o n i s t h e c l e a r e s t r e c o g n i z a b l e D4 e f f e c t .  gentle f o l d s  associated w i t h these kinks i s  gentle  The  plunge of  very  to  the  northeast  ( l i k e t h e d i p o f t h e f o l i a t i o n ) and t h e k i n k bands are steep t o v e r t i c a l  and s t r i k e N ( F i g u r e s 32a, b ) and are never more t h a n a few c e n t i m e t e r s i n w i d t h . F i g u r e 34 shows a d e t e r m i n a t i o n o f o r i e n t a t i o n s using the technique of  possible  D4 maximum compressive  Carter & Raleigh,  stress  (1969) f o r k i n k banding.  R e l a t i v e t o t h e present o r i e n t a t i o n o f t h e S2 f a b r i c i n Domain I I t h e D4 s t r e s s f i e l d should be o r i e n t e d w i t h t h e maximum compressive s t r e s s s l i g h t l y  inclined  toward t h e south e a s t . L a t e B r i t t l e Phase Late  high  angle f a u l t i n g o f t h e A n t l e r Formation c o n t a c t s has been mapped  by Campbell, R.B. (1978) and Campbell, K.v. (1971) t o t h e south near t o t h e nose o f Eureka S y n c l i n e ( t h e p a i r o f t h e Boss Mountain A n t i c l i n e ) . the  northwest  orientation  s i d e has moved southwestward r e l a t i v e of  this  feature i s similar  (i.e.  to  t h e southeast s i d e .  vertical,  maximum shown f o r f r a c t u r e s i n Domain I ( F i g u r e 3 5 a ) .  I t appears as though The  s t r i k i n g NE) t o t h e  To t h e n o r t h e a s t an e n t i r e l y  d i f f e r e n t maximum, shown i n F i g u r e 35b, t u r n s out t o be a s s o c i a t e d w i t h conjugate  Page 67  Structural Geology of Part of the Crooked Lake ftrea. Quesnel Highlands. British Colunbia  F i g u r e 35 - Contour p l o t s of poles t o f r a c t u r e s from Domains I & I I (contours represent 0,5,10% of p t s per 1% stereonet area) Page 613  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia f r a c t u r e p a i r s found t h r o u g h o u t Domain I I ; t h e o r i e n t a t i o n o f these p a i r s very c l o s e l y p a r a l l e l s these two planes.  Other f r a c t u r e s e t s c o n t a i n e d w i t h i n these  p l o t s can e a s i l y be r e l a t e d t o weaknesses i n t h e rocks due t o some or a l l o f t h e e a r l i e r deformations. Northwest (Montgomery,  trending  1978;  faults  Fletcher,  have been  in  adjacent  1972) w i t h some degree o f displacement.  t h e l i n e a r t r e n d o f Crooked Lake combined w i t h northeast i s  located  the  regions In fact,  extremely steep slopes t o t h e  s u g g e s t i v e t h a t a t l e a s t a prominent f r a c t u r e zone may be p o s i t i o n e d  there. I t  is  seriously  doubted,  continuity  of  t h e Crooked Lake  though,  units  that  on t h e  basis of  the stratigraphic  any c o n s i d e r a b l e s e p a r a t i o n has taken  place i n t h i s area. S t r u c t u r a l Summary Emplacement o f t h e A n t l e r Formation onto t h e Snowshoe may or may not have been a s s o c i a t e d w i t h D1 f o l d i n g .  The present author has chosen t o present  this  p o s s i b i l i t y i n t h e schematic summary ( F i g u r e 3 6 ) , but t h e reader must bear i n mind t h a t data f o r t h i s event i s l i m i t e d .  I t i s a l s o p o s s i b l e t h a t each u n i t  w i t h i t a unique episode o f d e f o r m a t i o n t o t h e i r c o u p l i n g l o c a t i o n .  carried  I t seems t h a t  t h e f i r s t d e f o r m a t i o n has not a f f e c t e d t h e s u r f a c e s e p a r a t i n g t h e Snowshoe and t h e Antler,  which leads t h e p r e s e n t a u t h o r t o b e l i e v e t h a t t h i s s u r f a c e i s  either  contemporaneous w i t h or p o s t - d a t e s D1 f o l d s (a t h r u s t f a u l t genesis c o u l d e x p l a i n t h i s temporal r e l a t i o n s h i p ) . An h i a t u s presumably separated t h e e a r l i e s t event a f f e c t i n g t h e Snowshoe and A n t l e r Formations f r o m t h e e v e n t u a l emplacement o f t h e t h r e e youngest u n i t s . it (e.g.  Again  i s not known whether t h i s emplacement was a s s o c i a t e d w i t h d e f o r m a t i o n or not t h e e a r l y 'open f o l d i n g ' phase o f D2 d e f o r m a t i o n c o u l d have formed d u r i n g  Page 69  S t r u c t u r a l Geology o f P a r t of the Crooked Lake Area, Quesnel Highlands, B r i t i s h C o l u n b i a  F i g u r e 36 - S c h e m a t i c s t r u c t u r a l  summary,  (a) A n t l e r Formation i s  on t o p o f t h e Snowshoe F o r m a t i o n w i t h a t t e n d a n t 01 f o l d i n g , t h r e e u n i t s a r e emplaced a t o p t h e the crust  thrust  p i n c h i n g out of the Eureka Q u a r t z i t e . develops p a r a l l e l f o l d s , increases,  parallel  limb thinning of  (c) Early  similar  of  the  s t a g e o f D2 d e f o r m a t i o n  and d e g r e e o f folding,  and  deformation considerable  ( e ) D3 f o l d i n g p r o d u c e s p r e s e n t day Page 70  level  s p l i c i n g may a c c o u n t f o r  ( d ) As t e m p e r a t u r e s  f o l d i n g g i v e s way t o units,  ( b ) The u p p e r  lower two presumably at a h i g h e r  (no a s s o c i a t e d d e f o r m a t i o n ) ;  emplaced  pattern  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia emplacement).  I t i s c l e a r t h a t t h e D2 d e f o r m a t i o n has a f f e c t e d a l l major o o n t a o t s  which s e t s a pre or syn-D2 date on t h e t i m e t h a t t h e f i v e u n i t s have shared a common history. The second d e f o r m a t i o n r e p r e s e n t s an extreme i n t h e k i n e m a t i c h i s t o r y o f t h e area.  P a r a l l e l f o l d i n g o f t h e rock u n i t s (as evidenced by open f o l d packages)  eventually  gave  way t o  more  extreme  f o l i a t i o n development ( F i g u r e 36 c, d ) . overall  tectonic  conditions  flattening,  folding,  and  intense  Obviously t h i s event occurred a t a t i m e when  were changing,  probably i n c r e a s e o f t e m p e r a t u r e ) .  shear  ( t h e most i m p o r t a n t  of  which was  The major compressive s t r e s s e s causing these  e f f e c t s were most l i k e l y d i r e c t e d f r o m an o r i e n t a t i o n p l u n g i n g s l i g h t l y toward t h e northeast;  this  orientation  is  suggested  by  the  vergence  shown by  the  B a s s e t / S t a r k p a i r when t h e y are u n f o l d e d about an average D3 f o l d a x i s t o  D2 the  northwest. The  subsequent  03  event  is  mainly  evidenced by t h e  o r i e n t a t i o n o f D2 elements between t h e two Domains ( F i g u r e 3 6 e ) .  gross  change  in  I n o t h e r areas, t o  t h e south and west (Montgomery, 1978; Murphy and Rees, 1983) a s i m i l a r o r i e n t a t i o n change f o r  contemporaneously  formed elements has been a t t r i b u t e d t o  d e f o r m a t i o n a l s t y l e w i t h depth i n t h e l i t h o l o g i c p i l e ( i . e . forms w i t h  depth).  In  the  present  study,  stratigraphic  changing  f l a t t e n i n g of continuity  fold  forces  a  d i f f e r e n t i n t e r p r e t a t i o n f r o m t h e f a u l t s s e p a r a t i n g low and h i g h grade zones o f Montgomery,  (1978) and t h e t h i c k n e s s o f rock considered combined w i t h e a s t / w e s t  v a r i a t i o n ( i n s t e a d o f n o r t h / s o u t h ) r u l e s out t h e a p p l i c a b i l i t y o f Murphy and Rees', (1983) f i n d i n g s t o t h e Crooked Lake a r e a . Unfortunately,  there  remains  proposed D3 event c o n s i s t e n t l y  some s i g n i f i c a n t  ambiguity  as t o  how  the  e f f e c t s D2 elements across t h e two Domains. The  Page 71  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia placement and o r i e n t a t i o n o f t h e Boss Mountain A n t i c l i n e and minor Domain I I are r e l a t i v e l y forms  elsewhere  consistent  w i t h each o t h e r ;  are s i m i l a r l y o r i e n t e d .  it  f o l d forms from  should f o l l o w  t h a t D3  What we see, though, i n Domain I are f o l d  forms w i t h t h e a p p r o p r i a t e placement and o r i e n t a t i o n ,  but w i t h a s s o c i a t i o n s t h a t  very s t r o n g l y suggest these f o l d s are o f t h e same g e n e r a t i o n as those f o l d e d by D3 i n Domain I I ,  i.e.  D2 f o r m s !  original  orientation  allowed  certain parts  cause  strain to  c r e a t i n g new ones. oleavages,  be  for  The present author  D2 f a b r i o s  within  suggests  that  an unusual  D3 d e f o r m a t i o n f i e l d s may have  o f t h a t f a b r i c (Domain I ) t o r o t a t e i n t o p o s i t i o n s t h a t taken  up by t i g h t e n i n g o f e a r l i e r f e a t u r e s  rather  than  D3 forms are b e l i e v e d t o o n l y be represented i n Domain I by  c r e n u l a t i o n s , and t h e wavy f o r m o f t h e S2 f o l i a t i o n .  The D3 event i s b e l i e v e d t o r e s u l t f r o m a compressive maximum s t r e s s d i r e c t e d f r o m an o r i e n t a t i o n s l i g h t l y i n c l i n e d toward t h e southwest; t h e evidence f o r t h i s i s from t h e vergence o f t h e Boss Mountain A n t i c l i n e / E u r e k a S y n c l i n e p a i r as shown on oross s e c t i o n s o f Campbell,  K.V.  (1971).  The l e v e l temperature  (and p o s s i b l y  p r e s s u r e ) e x i s t i n g d u r i n g t h i s event were c e r t a i n l y much lower t h a n d u r i n g t h e p r e v i o u s episode; i n t h i n s e c t i o n ,  it  i s r a r e t o see growth o f c h l o r i t e  and/or  muscovite p a r a l l e l t o a S3 oleavage (see METAMORPHISM below). The f o u r t h episode r e p r e s e n t s an e n t i r e l y d i f f e r e n t s t r e s s f i e l d than c o u l d be p o s t u l a t e d f o r t h e e a r l i e r e v e n t s , i . e. maximum compression f r o m t h e southeast. I t s e f f e c t d i f f e r e d between t h e two domains l a r g e l y because o f t h e o r i e n t a t i o n o f the  different  fabrics;  in  Domain I  positioned f o r f o l d i n g t o take place.  foliations  and cleavages  were  favourably  I n Domain I I f o l i a t i o n s presumably l a y a t an  angle t o t h e maximum compressive s t r e s s t h a t f o r c e d a l a r g e amount o f s h e a r i n g and  Page 72  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Columbia l o c a l development o f k i n k i n g ; had t h i s event been l o n g e r l a s t i n g , i t i s p o s s i b l e t h a t more e x t e n s i v e k i n k development across Domain I I would have r e s u l t e d . The l a s t major event t o have deformed t h e Crooked Lake rock u n i t s has been a s s o c i a t e d w i t h f r a c t u r e s u r f a c e s t h a t l o c a l l y occur t o g e t h e r as a conjugate s e t . S u r p r i s i n g l y each Domain i s a s s o c i a t e d w i t h one o f t h e p a i r ; Domain I c o n t a i n s t h e northeast s t r i k i n g  s e t and c o m p l e t e l y  lacks representatives of the other  F i g u r e 35a), whereas Domain I I c o n t a i n s m o s t l y t h e n o r t h s t r i k i n g s e t .  (see  Since f a u l t s  i n t h e area mostly belong t o t h e n o r t h e a s t s e t , i t i s t h e most l i k e l y s u r f a c e along which movements and b r e a k i n g c o u l d have o c c u r r e d .  Domain I I , however, has p r o v i d e d  t h e D5 s t r e s s f i e l d w i t h a p r e e x i s t i n g a l t e r n a t i v e (D4 k i n k band boundary p l a n e s ) , which j u s t happens t o be a c o n j u g a t e t o t h e n o r t h e a s t s e t .  The l i k e l y s t r e s s f i e l d  t o produce these s u r f a c e s i s w i t h maximum compressive s t r e s s d i r e c t e d toward t h e NNE and i s i n d i c a t i v e o f t r a n c u r r e n t f a u l t i n g (Anderson, ( 1 9 5 1 ) ) .  Page 73  Structural Geology of Part of the Crocked Lake Area. Quesnel Highlands. British Colunbia METAMORPHISH Introduction The process o f metamorphism i s number o f i m p o r t a n t ways. controlled should  factors  intrinsically  In the f i r s t  such  show a s y s t e m a t i c  p l a c e both  as pressure  and  r e l a t e d t o deformation i n a are  temperature  Next, i t has been observed t h a t t h e p h y s i c a l  deformation  o f t e n r e s u l t i n t h e same f e a t u r e s ,  metamorphically these e f f e c t s  grown mica  are  metamorphic  and/or  and as a consequence  o r amphiboles),  the l i t h o l o g i c / s t r u c t u r a l e f f e c t s o f metamorphism and  ( e . g . f o l i a t i o n s are formed of  and i n t h e case of  seen t o change as a r e s u l t o f l i t h o l o g i c  e x i s t i n g bodies o f rock.  on e x t e r n a l l y  v a r i a t i o n at d i f f e r e n t positions w i t h i n gradient f i e l d s  o f these two v a r i a b l e s ( p r e s s u r e i n c l u d e s depth w i t h i n pile).  dependent  Finally,  both  processes,  variation within  the  t i m e bounds t h e b e g i n n i n g and end o f d i s c r e t e  d e f o r m a t i o n a l events  and i n f l u e n c e s c e r t a i n r a t e s i m p o r t a n t  t o t h e completion o f a process o r g e n e r a t i o n o f e f f e c t s o f a process. Metamorphism, reactions  that  in  of  the  concerned  t h e pressures  t h i s includes a l l  a vapour phase. t h a t allow  is  concerned w i t h t h e s e r i e s  can occur t o any composition t y p e  d i a g e n e t i c processes t o Figure 37);  general,  from the  and temperatures  time  is  limit  of  where m e l t i n g occurs (see  r e a c t i o n s t h a t i n v o l v e s o l i d phases w i t h or w i t h o u t  These r e a c t i o n s  but as f a r  possible  upper  are,  o f course,  s u b j e c t t o t h e laws of k i n e t i c s  f o r t h e occurrence o f deep-seated m i n e r a l assemblages  earth,  of  as  usually  'normal* not  prograde metamorphic  a significant  factor  at the  surface  processes  so t h e  theory  are of  thermodynamic e q u i l i b r i u m can s a f e l y be assumed.  The two most i m p o r t a n t f a c t o r s  used t o prove t h e  reaction  existence  of  a  possible  (and  accompanying  e q u i l i b r i u m ) are t h e t e x t u r e s w i t h i n and among e x i s t i n g m i n e r a l phases and  Page 74  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia  100  200  300  400  500  600  700  800  T, C W  F i g u r e 37  -  observation  Pressure and temperature ranges f o r metamorphism and f a c i e s s u b d i v i s i o n of t h e ' P - T ' f i e l d (adapted f r o m Turner [1981] p. 420) of t h e number o f e x i s t i n g  phases  t h a t should be i n accord w i t h t h e  phase r u l e : F - C - P + 2 (F i s t h e degrees o f freedom i n p r e s s u r e / t e m p e r a t u r e space [ t h i s should be one i n t h e case o f a s i n g l e r e a c t i o n ] , C i s t h e number o f components i n t h e system, P i s t h e number o f phases i n t h e system, and t h e 2 r e f e r s t o t h e two externally controlled factors, pressure and t e m p e r a t u r e ) . The p h y s i c a l significance of  Page 75  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia  TABLE II-A  DISTRIBUTION OF MINERAL ASSEMBLAGES I N DOMAIN I OF THE CROOKED LAKE AREA  SW  NE_  T Cc-gt2-Chl-Hnbd-Ep-Musc-Ab A Hnbd-Ep-Cc-Qtz-Musc-Ab K Cc-Ep-Chl-Qtz-Ab-Act L Act-Chl-Qtz-Cc-Ab A Chl-Qtz-Ab  c  —S—n—i  L J  R 0 0 K E D  n  1  Chl-Graph-Qtz-Musc Musc-Qtz-Chl-Ank Cc-Chl-Graph-Qtz-Musc Musc-Chl-Qtz Py-Qtz-Kspar Chl-Gn-Staur-Ilm-Musc-Qtz Chl-Musc-Otz-(Graph) Qtz-Musc-Ank Musc-Ank-Qtz-Chl Ilm-Graph-Chl-Qtz-Musc Ilm-Chl-Musc-Qtz-Graph  P H Y L L I L T A E K L  1  1  1  1  1  H  1  Mgt-Chl-Qtz-Ab Musc-Bio-Chl-Ep-Olig Py-Musc-Qtz-Ank Ep-Ilm-Bio-Olig-Chl-Qtz Ep-Ilm-Chl-Cc-Qtz-Olig A N T L E R  Qtz-Mgt-Ep-Chl-Cc-Ab Chl-Ep-Qtz-Cc-Ab Cc-Chl-Ep-Ab-Hnbd/Act Cc-Mgt-Qtz-Chl-Hnbd-Ab-Ep (Bio)-Ep-Hnbd-Mgt-Chl-Otz Hnbd-Ab-Chl-Qtz-Ep Mgt-Cc-Chl-Ep-Hnbd/Act-Qtz Cc-Serp-Opx-Ol Chl-Cc-Otz-Ab-Ep Mgt-Hnbd/Act-Chl-Ep-Qtz-Ab Chl-Felsic-Ep-Hnbd/Act Hnbd-Chl-Ep-Qtz  : _ _  N H 0 0 • E  L_U  .  I  L  I |  (Ands)-(Bio)-Musc-(Chl)-Qtz Qtz-Musc-Cc (01ig)-(Chl)-(Perth)-Musc-Bio-Qtz  NOTE: The vertical lines in these Tables are neant to designate the relative placenents of assenblages or flioups of assenblaoes on an hypothetical section line across the specific Dowain.  Page 76  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia  TABLE II-B  DISTRIBUTION OF MINERAL ASSEMBLAGES I N DOMAIN I I OF THE CROOKED LAKE AREA  NW  T A K L A  n—n  SE Qtz-Hnbd-Ep-Chl-Ab Chl-Qtz-Hnbd-Ep-Ab Opaq-Chl-Qtz-Ab I  rm  1  Hnbd-Ep-Bio-Felsic-Act Bio-Ep-Act-Felsic Musc-Py-Ab-Qtz-Cc Musc-Cc-Ank-Ep-Ab-Qtz  C R 0 0 K E D  P H Chl-Musc-Otz Y Chl-Musc-Qtz-Graph L Musc-Qtz-Chl-Ank Chl-Musc-Qtz-Graph L Chl-Graph-Qtz-Musc Graph-Chl-Qtz-Musc I Ctd-Ilm-Chl-Musc-Ands-Qtz L T Chl-Ctd-Ilm-Graph-Ands-Qtz-Musc A E Ctd-Ilm-Gn-Chl-Graph-Ands-Musc-Qtz K Gn-Ilm-Ctd-Musc-Chl-Qtz E Chl-Musc-Qtz-Graph Graph-Chl-Cc-Qtz-Musc  I  LLU  EQ  U  I  1^  R T E I K T  Opaq-Chl-Musc-Bio-Olig-Qtz  u z  " A N T L E R  1 N 0 • S H 0 E  U  Ep-Hnbd-Bio-Qtz Gn-Mgt-Chl-Musc-Bio-Qtz  1  1  1  1  Ilm-Ep-Parg-Ab-Chl-Bio-Hnbd-Qtz Cc-Qtz-Ep-Chl-Ab-Hnbd Ep-Ab-Opaq-Qtz-Hnbd Opaq-Chl-Ab-Cc-Hnbd-Qtz (Ands)-Act-Clz-Chl-Qtz Cc-Ands-Qtz-Clz-Chl Ep-Ands-Hnbd Ep-Felsic-Hnbd Ands-Act-Clz Felsic-Clz-Act  1  1 —  I  I  1  !  1 —  1  (Ilm)-Bio-Musc-(01ig)-Qtz Bio-Musc-Qtz-(Feld) (01ig)-(Bio)-Musc-Qtz (Musc)-(Gn)-Bio-Qtz Qtz-Musc-Cc Qtz-Ep-Hnbd Gn-Bio-Musc-Qtz-Ands Page 77  1  I  Structural geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia r e a c t i o n s as s u r f a c e s and p l a n a r - l i k e volumes can be t a k e n i n t o account by d e t a i l e d sampling and comparison o f samples o f s i m i l a r t o equal composition t y p e . A q u a n t i t a t i v e e s t i m a t e o f t h e pressures one or more metamorphic events can be reaction  assemblages  in  f i n d i n g s w i t h work done environment ( t h i s  thin  sections  on these  same  e s t i m a t e d by i d e n t i f y i n g or or  in  the f i e l d  t o be u s e f u l i n t h i s r e g a r d f o r t e x t u r a l readjustment  to  may show  minimal  and t e x t u r a l  s h o r t , one i s faoed w i t h t h e dilemma o f choosing t o are s u i t a b l y  reactive  w h i l e keeping r e a c t i o n s  as w e l l  can be expected  ohanges  outside of  w h i l e o t h e r t y p e s may  transformations the  which can h a r d l y be expected t o be r e p r o d u c i b l e i n t h e  that  determinations  the l o c a l stress conditions,  repeated m i n e r a l o g i c a l  these  reactions i n the experimental petrology  Not a l l composition t y p e s  some  during  inferring  and c o r r e l a t i n g  w i l l i n o l u d e t h e o r e t i c a l thermodynamic  as r e v e r s a l e q u i l i b r i a e x p e r i m e n t s ) .  undergo  and temperatures a t t a i n e d  complexity  of  l a b o r a t o r y environment.  In  observe  composition  t o p r o v i d e meaningful r e a c t i o n d a t a ,  and assemblages as simple as i s  types  on t h e one hand,  warranted by  current  t h e o r e t i c a l and e x p e r i m e n t a l r e s e a r c h . Ultimately  t h e study o f t h e metamorphic h i s t o r y o f an  q u a l i t a t i v e statement events.  area should y i e l d a  o f t h e r e l a t i o n s h i p between metamorphic  T h i s has been accomplished, i n t h e present study,  m i n e r a l s as observed i n t h i n s e c t i o n s t o t h e development known f r o m t h e o u t c r o p s c a l e .  and d e f o r m a t i o n a l  by r e l a t i n g of  growth  of  structural features  Metamorphism i s b e l i e v e d t o c o i n c i d e w i t h t h e f i r s t  t h r e e d e f o r m a t i o n a l events (see F i g u r e 5 0 ) , o c c u r r i n g as t h r e e d i s t i n c t pulses o f metamorphic a c t i v i t y (M1, M2, and M3, w i t h r e s p e c t t o o l d e s t u n i t s ) . Assemblages c h a r a c t e r i s t i c o f t h e Crooked Lake u n i t s are o u t l i n e d i n Table I I - A , B ( n o t e : m i n e r a l names g i v e n i n ' l e a s t - t o - m o s t ' f o r m a t ) ; t h e present author  Page 78  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia has  chosen t o  groups  (quartzo-feldspathic,  these  assemblages  pelitic,  into  five  major  compositional  types  b a s i c , c a l c a r e o u s , u l t r a m a f i c ) t h a t correspond t o  those o f t e n c i t e d i n t h e metamorphic l i t e r a t u r e , (Turner [ 1 9 8 1 ] ; M i y a s h i r o [ 1 9 7 3 ] ) . The f o l l o w i n g i s a d e t a i l e d t r e a t m e n t  of  t h e assemblages  c o r r s p o n d i n g t o each  compositional type w i t h consideration given p a r t i c u l a r i l y t o possible and  experimental  s u p p o r t i n g evidence;  reactions  d e t a i l e d p e t r o l o g i c i n f o r m a t i o n can be  found i n Appendix A. Q u a r t z o - F e l d s p a t h i c Type This  c o m p o s i t i o n a l t y p e i s c h a r a c t e r i z e d by an abundance o f q u a r t z and  f e l d s p a r s i n c e rocks o f t h i s t y p e are u s u a l l y quartzose  sedimentary  rocks.  The Snowshoe  almost e n t i r e l y of t h i s c o m p o s i t i o n t y p e ; minor  amounts o f q u a r t z o - f e l d s p a t h i c The  most  muscovite-quartz main  common  t h e o t h e r t h r e e u n i t s c o n t a i n moderate t o  seen  quartz  in  this  composition  domain  are known t o occur  over  garnet,  and  facies;  biotite  preferential  and  Miyashiro,  temperatures 1973). The  probably r e p r e s e n t  appearance  of  compositional  chlorite  in  o t h e r s c o u l d be taken as an i n d i c a t i o n  grade.  to  be  rocks  above  t h e Eureka  the  Quartzite  sole and  mafic  mineral  the Antler  Page 79  of  and  changing  i n quartzofeldspathic  Formation,  rocks below and e s p e c i a l l y toward t h e east and southeast  of  variation,  some l o c a l i t i e s  in  seems  ( f r o m upper  occurrence  chlorite-garnet- biotite Chlorite  The two  r e f l e c t i n g h e t e r o g e n e i t y o f s u b u n i t s ) and  a wide range o f pressures  z e o l i t e t o middle a m p h i b o l i t e  is  show l i t t l e change across t h e f i e l d area  abundance ( p r o b a b l y  the  and micaceous q u a r t z i t e are composed  (± c h l o r i t e ± b i o t i t e ± garnet ± f e l d s p a r ) ( F i g u r e 3 8 ) .  except i n r e l a t i v e  though  igneous rocks or  rocks.  assemblage  m i n e r a l s muscovite and  chlorite,  derived from acid  whereas  biotite  in  the  and garnet  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia  F i g u r e 38a -  B i o - q t z s c h i s t w i t h minor muscovite and p o r p h y r o b l a s t o f g a r n e t ; micas and ' c r y p t o c r y s t a l l i n e ' banding ( f e l s i c s ? ) d e f i n e S2 f o l i a t i o n { c r o s s - n i c o l s i n s e r t e d , X12.5, LOC-RZ10}  a l i g n e d w i t h S2 f o l i a t i o n d e f i n e d by micas { c r o s s - n i c o l s i n s e r t e d , X12.5,L0C-RZ10}  Page 80  Structural Seology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia are  of increasing  importance.  Reactions i n v o l v i n g t h e d e s t r u c t i o n  and subsequent f o r m a t i o n o f b i o t i t e are t y p i c a l o f and 1968,  garnet s t a r t s  to  form  at  greenschist  facies  the greenschist/amphibolite t r a n s i t i o n  (Turner  1980). Plagioclase  I n Domain I ,  f e l d s p a r i s e x c l u s i v e l y found i n t h e groundmass w i t h q u a r t z .  a l l quartzo-feldspathic units  above t h e A n t l e r Formation have a l b i t e  as t h e s o l e p l a g i o c l a s e , whereas p l a g i o c l a s e or  t h e upper  of o h l o r i t e  below  the Antler  were  i n s i m i l a r u n i t s found a t t h e base o f  found t o range from An22 t o An24.  c a u t i o n must be made, however.  Firstly,  Two  points  of  i n terms o f t h e r e a c t i o n t h a t may be  r e s p o n s i b l e f o r t h i s change: a l b i t e + epidote - o l i g i o c l a s e + epidote c l i n o z o i s i t i c e p i d o t e i s not c o n s i s t a n t l y found t o occur w i t h a l l o f t h e observed plagioclases,  and secondly t h e r e i s a very l a r g e gap (1 t o 3 km t h i c k n e s s ) between  albite-bearing  and  quartzo-feldspathic quartzo-feldspathic oligoclase-bearing Snowshoe Formation;  oligoclase-bearing rocks rocks  were  found.  were  found  assemblages  were  where no In  recorded  plagioclase-bearing  Domain  i n the  a l l o f these occurrences  but again t h e t h i c k n e s s o f  in  Takla the  did involve  II  albite-bearing  Group  rocks  Eureka Q u a r t z i t e  and and  c l i n o z o i s i t i c epidote,  rock between t h e d i f f e r e n t p l a g i o c l a s e assemblages was  l a r g e (1 t o  2 km).  confidently  placed except t o say t h a t t h e  i s on i t s  units  Unfortunately  an  isograd  based on t h i s data  structurally  downgrade s i d e and t h e s u r f a c e  must f a l l  highest u n i t  cannot in  be  the p i l e  somewhere (and w i t h some  u n c e r t a i n shape) w i t h i n t h e mass o f t h e Crooked Lake P h y l l i t e . Potassium Lake area.  f e l d s p a r was found a t two d i f f e r e n t l o c a l i t i e s i n t h e  Crooked  I n t h e Crooked Lake P h y l l i t e a p y r i t i c sandstone found a t one l o c a l i t y  Page 81  Structural Seology of Part of the crooked Lake Area. Quesnel Highlands. British Colunbia (J41)  is  composed  (myrmekitic-like) widespread,  -  moderately  inclusions  apparent r e l i c t  s t i l l discernable  F i g u r e 39  of  of  quartz.  clastic  Though  grain  and  with  abundant  recrystallization  cement  relationships  is are  material  B i o t i t e q u a r t z i t e o f Eureka Q u a r t z i t e w i t h magnetite v e i n i n g and unusual hornblende c r y s t a l s ; t h e b i o t i t e here i s green; o r d i n a r i l y i t i s brown and muscovite i s t h e more common mica (Plane p o l a r i z e d l i g h t , X12.5,L0C-J104) The Snowshoe Formation o f Domain I c o n t a i n s  p o r p h y r o b l a s t s , again found a t o n l y one coarse c r y s t a l s o f t e n c o n t a i n to  orthoclase  i n p l a n e - p o l a r i z e d l i g h t o u t l i n e d by very f i n e opaque  a t o l d g r a i n boundries.  angle  sericitized  and not continuous  a metamorphic  l o c a l i t y (RZ10; see F i g u r e 3 8 ) .  f i n e opaque with  the  inclusion  trails  main f o l i a t i o n .  Page 82  These  t h a t are a t a high  This  o r i g i n , i m p l y i n g t h a t they would have formed  perthite  at  fact  may suggest  an  e a r l i e r time  structural Geology of Part of the crooked Lake Area, Quesnel Highlands, British Coluwbia t h a n t h e 02 event a t  a  grade s u f f i c i e n t f o r K - f e l d s p a r  formation;  t h e most  probable r e a c t i o n f o r t h i s c o m p o s i t i o n t y p e would be: Muscovite + Quartz = K - f e l d s p a r + Al2Si0s + H2O which 1972,  from  t h e r e v e r s a l e q u i l i b r i a o f numerous  workers  (Evans 1965,  Kerrick  C h a t t e r j e e and Johannes 1974) i s known t o be c h a r a c t e r i s t i c o f t h e upper  a m p h i b o l i t e f a c i e s ( e . g . 5 k i l o b a r s & 700 degrees C ) .  Of course, i t i s a l s o l i k e l y  t h a t t h i s potassium f e l d s p a r belongs t o a primary mineralogy t h a t has s u r v i v e d t h e v a r i o u s metamorphic episodes. Textures quartz  and  in  these  r o c k s are c o n t r o l l e d  feldspars.  These  minerals  by  are c h a r a c t e r i s t i c a l l y  elongate i n form and so i m p a r t a f o l i a t i o n t o t h e and i t i s a local  not  uncommon f o r  scale,  sub-division)  rock  as  a  of equant  the to  whole ( F i g u r e 3 8 ) ,  f e l d s p a r e l o n g a t i o n t o be extremely w e l l developed on  as w e l l ( F i g u r e 3 8 b ) .  (undulatory e x t i n c t i o n ,  the prismatic nature  deformation  i s always apparent.  Internal  deformation  banding and t w i n n i n g , Micas  lie  in  all  felsics  p a r t i a l internal grain  mostly p a r a l l e l t o t h e S1 or S2  f o l i a t i o n s ; those t h a t l i e a t a h i g h angle t o a p a r t i c u l a r f o l i a t i o n (say S2; see F i g u r e 40) probably belong t o an e a r l i e r formed (S1) f o l i a t i o n . 38)and magnetite are s k e l e t a l t o s u b i d i o b l a s t i c  Garnets ( F i g u r e  and i d i o b l a s t i c , r e s p e c t i v e l y or  occur t o g e t h e r i n v e i n s w i t h q u a r t z t h a t l i e s u b - p a r a l l e l t o t h e main f o l i a t i o n ( F i g u r e 39 shows magnetite v e i n i n g p a r a l l e l t o S2 i n Eureka Q u a r t z i t e ) . P e l i t i c Type Rocks  of  a pelitic  composition  are  usually  derived  from f i n e  grained  sediments r i c h i n aluminum and potassium; f o r t h i s reason t h e most common m i n e r a l s observed i n p e l i t e s texture.  are  micas  which i m p a r t t o t h e rock a s c h i s t o s e or f o l i a t e d  The Crooked Lake P h y l l i t e i s composed o f over 80% o f t h i s  Page 83  composition  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia type (Figure 41), interlayered  F i g u r e 40  -  Two  Snowshoe's q u a r t z o - f e l d s p a t h i o r o c k s  are  often  P e l i t i c s c h i s t f r o m Snowshoe Fm.; an e a r l i e r f o l i a t i o n S1 has been d i s r u p t e d by t h e S2 f o l i a t i o n ; numerous ' h i g h angle* b i o t i t e s are common ( t o p o f p h o t o ) and are crossed by S2 muscovites ( c r o s s - n i c o l s , X12.5, L0C-RZ10) assemblages  while  tchloritoid  the  with p e l i t i c schists (Figure 40).  muscovite-quartz observed,  and  are  common  (tplagioclase)  is  in  this  generally  domain; typical  of  chlorite-'graphite'-muscovite-quartz  tstaurolite  tplagioclase)  is  characteristic  chlorite-biotiteSnowshoe  (tgarnet of  pelites tilmenite  the  Crooked  Lake  in a  similar  way  Phyllite. The as  their  quartz,  pelitic  rocks o f t h e Snowshoe vary i n  interlayered  muscovite,  composition  quartzo-feldspathic equivalents.  and b i o t i t e t e n d t o  The p r o p o r t i o n s of  change u n s y s t e m a t i c a l l y and  of low t o medium a n o r t h i t e c o n t e n t ( f r o m An35 t o An^n) occurs l o c a l l y . of  these rocks are governed by t h e micas Page 84  plagioclase The t e x t u r e s  (as opposed t o t h e f e l s i c s ;  compare  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia bottom and t o p o f F i g u r e s 38 and 40, r e s p e c t i v e l y ) . poorly  represented f a b r i c s were  t h e main metamorphic event,  observed.  obvious macroscopic  first  obvious  the less  foliation  consisting  of  d i s r u p t e d and o r o s s - o u t  F i g u r e 41  folded  -  main f a b r i c  has a l l o w e d e x t e n s i v e  defines the grossly of  The  One dominant  fabrics  high  corresponding t o  p a r a l l e l mica growth  f o l i a t i o n seen across t h e area.  is a biotite  angle  f a b r i c and two  (w.r.t.  (less  commonly  main f o l i a t i o n )  that The  muscovite)  masses of  mica  by t h e main f o l i a t i o n ( F i g u r e 40) or i s o c l i n a l l y  Open f o l d i n g i n Crooked Lake P h y l l i t e (a s l a t y s u b l i t h o l o g y ) ; note dark l a y e r s have l a r g e amount o f g r a p h i t e t h a t has been i n j e c t e d up i n t o S2 cleavage planes ( p r o b a b l y w h i l e u n i t was s t i l l unconsolidated and wet) ( c r o s s - n i c o l s , X12.5, L0C-J7)  arrangements of mica l y i n g p a r a l l e l  to  the f o l i a t i o n ;  t h i s has been  i n t e r p r e t e d as i n d i c a t i v e o f an e a r l i e r metamorphic event (M1).  The second f a b r i c  i n v o l v e s t h e growth of muscovite  D3  spaced cleavages  and  and  chlorite  parallel  to  appears t o accompany t h e c r e n u l a t i o n of t h e  commonly seen across t h e a r e a ;  t h i s feature  Crooked Lake area. Page 85  is  deformational main f o l i a t i o n  o n l y seen i n Domain I I o f t h e  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia I n t h e r o c k s o f t h e Crooked Lake P h y l l i t e t h e p r o p o r t i o n s o f muscovite, quartz,  and * g r a p h i t e '  interbeds.  vary somewhat i r r e g u l a r l y as does t h e g r a i n s i z e o f t h e  The f u l l speotrum o f mica f o l i a t i o n  F i g u r e s 41 t o 44) f r o m ( w i t h accompanying  microscopic  growth p a r a l l e l  was observed  (see  t o a x i a l planes o f open f o l d s  s o f t - sediment i n j e c t i o n i n t o cleavage planes on t h e mesoscopic  s c a l e , see F i g u r e 41) t o ( w i t h accompanying  development  domination  o f t h e t o t a l f a b r i c by t h e mica  transposition of a l l layering sub-parallel t o  F i g u r e s 42, 43, and 4 4 ) .  foliation  this foliation.  T h i s f o l i a t i o n i s very o f t e n seen c r e n u l a t e d , though t h e  e x i s t e n c e o f mioa growth p a r a l l e l t o D3 s t r u c t u r e s (as i n t h e Snowshoe) was not observed.  It  is  strongly  b e l i e v e d t h a t M2 ( a g a i n we c o u l d use an a l t e r n a t e  terminology,  such as {M1}) was t h e f i r s t metamorphic event t o a f f e c t t h e Crooked  Lake P h y l l i t e . So  far  t h e m i n e r a l assemblages mentioned above do  not  add any  more  d e t a i l e d i n f o r m a t i o n concerning grade t h a n those o f t h e q u a r t z o - f e l d s p a t h i c  rocks.  I t was,  fabric  of  constituent more  course,  observed  that biotite  seems  t o be an i m p o r t a n t H1  (over muscovite) and t h i s c o u l d be t a k e n t o suggest t h a t t h a t event was  or l e s s o f a h i g h e r grade t h a n M2;  no more can be s a i d  given the a v a i l a b l e data.  The f a c t t h a t b i o t i t e was r a r e l y  Crooked Lake P h y l l i t e  below  the  Snowshoe  i s important  Crooked Lake P h y l l i t e true  "biotite  (see  1  to  on d i s c u s s i o n o f  note.  o f t h i s e a r l y event observed  staurolite),  in  the  but i s common i n  I t i s p o s s i b l e t h a t t h e composition o f t h e  i s d i f f e r e n t enough from t h e Snowshoe p e l i t i c r o c k s t h a t a  i s o g r a d can  not  be p o s t u l a t e d  based  on t h i s evidence;  the  u b i q u i t o u s occurrence o f c h l o r i t e may i n d i c a t e u n u s u a l l y h i g h MgO/FeO r a t i o s f o r t h i s u n i t which i s known t o be r e s p o n s i b l e f o r t h e delay o f many b i o t i t e f o r m a t i o n i s o g r a d s (Chinner 1960).  Page 86  Structural Geology of Part of the Crooked Lake area. Quesnel Highlands. British Coluwbia  F i g u r e 42b -  Microscopic f a b r i c o f p o r p h y r o b l a s t i c p h y l l i t e showing p l a g and i l m p o r p h y r o b l a s t s i n m a t r i x o f m u s c o v i t e / s e r i c i t e - g r a p h i t e - q u a r t z ; S2 f o l i a t i o n t y p i c a l l y wrapped around p o r p h y r o b l a s t s ; S i i n p l a g = S o f f o l i a t i o n { c r o s s - n i c o l s i n s e r t e d , X12.5, L0C-J85} e  Page 87  Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia  F i g u r e 43a -  P o r p h y r o b l a s t i c p h y l l i t e w i t h p l a g , c t d , c h l , and i l m i n c o n t a c t ; c h l occurs i n c e n t e r o f c t d c r y s t a l ( d a r k ) , t h e corroded form o f which c o n t r a s t s w i t h u n i t s where c t d occurs w i t h no p l a g { p l a n e p o l a r i z e d light,X12.5,L0C-J85}  F i g u r e 43b -  Same sample as above w i t h c r o s s - n i c o l s i n s e r t e d ; S2 f o l i a t i o n though d e f l e c t e d by p o r p h y r o b l a s t s i s continuous w i t h i n c l u s i o n s i n c r y s t a l s {X12.5, L0C-J85}  Page 88  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia  F i g u r e 44a -  Garnet and i l m e n i t e w i t h i n p o r p h y r o b l a s t i c p h y l l i t e ; garnet shows r o t a t e d i n c l u s i o n s t h a t are continuous w i t h S2 f o l i a t i o n a t c r y s t a l boundaries { p l a n e p o l a r i z e d l i g h t , X50, L0C-J85}  F i g u r e 44b -  S t a u r o l i t e i n p o r p h y r o b l a s t i c p h y l l i t e w i t h S i • S&; b i o t i t e c r y s t a l nearby i s t h e o n l y example o f b i o t i t e i n Crooked Lake P h y l l i t e { c r o s s - n i c o l s i n s e r t e d , X12.5, LOC-J47}  Page 89  Structural Seology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Certain  poorly  defined  horizons  assemblages from which s i g n i f i c a n t  in  the  Crooked Lake P h y l l i t e  i s o g r a d s may be deduced.  contain  The bulk o f  this  p e l i t i c v a r i a n t occurs along t h e steep southwest slopes o f T a l b o t Ridge i n Domain I I and one  occurrence  unit  characterized  is  plagioclase,  crops out i n t h e northernmost p a r t o f by p o r p h y r o b l a s t i c  chloritoid  or  staurolite  q u a r t z ( F i g u r e s 42, 43, 44); be i n d i c a t i v e  of  within  a matrix  compositional  chloritoid,  chloritoid  and  the  Phyllite.  with  xenoblastic,  fine  Chloritoid  quartz  and  serrated outline  specimens,  occurs  main mica f o l i a t i o n pressure  100-150  opaques  Se) o f becomes  (high  should  AI2O3 & h i g h  (high  forms  (Si  angle c r y s t a l s  staurolite mass o f  coarse, s u b i d i o b l a s t i c , main  f o l i a t i o n and i s  parallel  Se);  garnets  platy highly have  a  ilmenite, i n t h i s  and  and/or  quartz  t o t h e lower Crooked Lake P h y l l i t e c o n t a c t i n  Domain  meters)  the  second  are  bent,  broken,  assemblage  is  porphyroblast forming  main f o l i a t i o n w i t h  quartz, ilmenite,  or  s u b i d i o b l a s t i c c r y s t a l s mostly a l i g n e d w i t h t h e  Andesine (An35) i s t h e most abundant aligned with the  staurolite  and r o t a t i o n a l i n c l u s i o n t r a i l s which i n most cases  as p l a t y  shadowed). Nearer  I I (within  or  ( F i g u r e 44a) t o g e t h e r  show S i continuous t o Se on t h e outermost c r y s t a l o u t l i n e s ; all  and  chlorite-muscovite-  i n Domain I I w e l l i n t o t h e  c r y s t a l s l y i n g a t low t o moderate angles t o t h e included  ilmenite,  p l a g i o c l a s e ( F i g u r e 43),  f i r s t assemblage o c c u r r e d  Lake  This  H a l f e r d a h l 1961).  ( F i g u r e 44b). T h i s Crooked  garnet,  range  A l l samples examined c o n t a i n e d g a r n e t and i l m e n i t e with  I (J47).  of  t h e occurrence o f c h l o r i t o i d  a fairly restrictive  Fe/Mg) (Hoschek 1969;  development o f  Domain  rotational  tourmaline,  augen-shaped  crystals  i n c l u s i o n t r a i l s ( S i continuous  muscovite,  p r o g r e s s i v e l y more corroded i n t h e v i c i n i t y  Page 90  more predominant.  and f i n e opaques; of  chloritoid  andesine ( F i g u r e s 43a,  b)  Structural Seology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia and/or  i n samples o c c u r r i n g f u r t h e r t o t h e northwest along these steep s l o p e s .  The t h i r d assemblage occurs as a s i n g l e exposure i n and  ilmenite  amounts  p o r p h y r o b l a s t s occur  of b i o t i t e .  direction  Domain I ;  staurolite,  garnet  i n the usual matrix w i t h the a d d i t i o n of small  Staurolite  is  idioblastic  with  the  long  crystal  (Z a x i s ) l y i n g w i t h i n t h e plane o f t h e main f o l i a t i o n ( F i g u r e 44b shows a  l e n g t h - f a s t / e n d s e c t i o n o f s t a u r o l i t e w i t h S2 p e r p e n d i c u l a r t o t h e t h i n s e c t i o n ) , d e f i n i n g a weak l i n e a r f a b r i c , (quartz  and p o s s i b l y r e p r e s e n t i n g an a x i s o f  i n c l u s i o n t r a i l s suggest t h a t  Si  may  is a  common a s s o c i a t e .  Garnet c r y s t a l s  with  strongly included  i d i o b l a s t i c rims.  be continuous  show  irregular  rotation  w i t h Se);  chlorite  weakly i n c l u d e d  cores  B i o t i t e occurs as x e n o b l a s t i c s m a l l  crystals. Within  the  volume spanned by t h i s s e r i e s  of  samples two d i s t i n c t m i n e r a l  assemblage p o p u l a t i o n s e x i s t ( c h l o r i t o i d - b e a r i n g versus  s t a u r o l i t e - b e a r i n g ) and a  p r o g r e s s i o n i n t i m e between t h e two may or may not have o c c u r r e d ; a r e a c t i o n o f t h e form: c t d + muse + q t z = s t a u r + b i o + H2O could  link  assemblages  the as  two  groups ( t h i s i s most  higher  grades  are  likely  to  occur  to  chloritoid  reached), a l t h o u g h s t a u r o l i t e assemblages  can be d e r i v e d f r o m r e a c t i o n s o f t h e f o r m : c h l + muse = s t a u r + b i o + q t z + H2O as  well  Hoschek  ( s t a u r o l i t e can e x i s t i n a wider range 1967).  of  composition t h a n  chloritoid;  Regardless o f t h e o v e r a l l s i m i l a r i t y o f t e x t u r e s and background  mineralogy between t h e s t a u r o l i t e assemblages  two groups, w i t h o u t and/or  chemical  r e a c t i o n i s most l i k e l y r e p r e s e n t e d .  certain  intermediate  analyses i t i s d i f f i c u l t  Fortunately  Page 91  these r e a c t i o n s ,  chloritoid-  to  show which  along w i t h a  Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia series of  related  occupy a  pelitio  r e a o t i o n s {Ganguly  r e s t r i c t i v e temperature  kbars. Some  additional  amount  1969,  Hosohek 1969,  Albee 1972}  range o f 500 t o 575° C a t pressures o f 4 t o 7  o f u n c e r t a i n t y may be  due  to  unknown values o f  t h e p a r t i a l pressure o f water and f u g a c i t y o f oxygen a t t h e t i m e these r e a c t i o n s would have o c c u r r e d . An a d d i t i o n a l r e a c t i o n may be suggested by t h e t e x t u r a l r e l a t i o n s observed i n c h l o r i t o i d - p l a g i o c l a s e b e a r i n g u n i t s ( F i g u r e 39b shows corroded c h l o r i t o i d i n t h e presence o f p l a g i o c l a s e ) .  A c c o r d i n g t o t h e e x p e r i m e n t a l work o f Hoschek,  (1969)  the reaction: Chl + Para + Qtz - Ctd + Ab + vapour was found t o have a r e s t r i c t e d temperature range (510°-570°C) and be r e l a t i v e l y independent o f pressure (see  PT diagram. F i g u r e 47, b e l o w ) ; t h e assemblage p a i r  c t d - a b was s a i d t o be r e l a t i v e l y  r a r e because o f t h e c l o s e p r o x i m i t y  of  this  r e a c t i o n t o c h l o r i t o i d ' s s t a b i l i t y l i m i t s i n t h e upper r e g i o n s o f t h e g r e e n s c h i s t faoies.  Since p l a g i o c l a s e ,  and n o t a l b i t e ,  i s involved with o h l o r i t o i d i t  is  believed t h a t a counterpart s l i d i n g r e a c t i o n t h a t takes the various s o l i d s o l u t i o n s i n t o account would have t h e above r e a c t i o n as one end l i m i t . Basic Type This epidote,  composition t y p e i s  as c h l o r i t e ,  a c t i n o l i t e , and hornblende w i t h l e s s t h a n or equal amounts o f  and sometimes q u a r t z ; rocks,  c h a r a c t e r i z e d by m i n e r a l s such  a l i k e l y parentage would be i n t e r m e d i a t e t o b a s i c igneous  m a f i c graywackes,  Formation  feldspars  and  volcaniclastic  and t h e Takla Group r o c k s f a l l i n t o  t h e former i s more b a s i c i n  composition;  Page 92  this  sediments.  the  Antler  composition category,  though  the other  units  Both  show  o n l y minor  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Columbia representation i n  rocks  of  t h i s t y p e t h e most n o t a b l e o f whioh i s t h e qtz-ep-hnbd  s c h i s t found i n Domain I I .  F i g u r e 45  -  The  Chl-Hnbd-Ep-Qtz Meta-wacke; mafic m i n e r a l s d e f i n e t h e S2 f o l i a t i o n i n these and o t h e r b a s i c u n i t s (plane p o l a r i z e d l i g h t , X12.5, L0C-RZ4) most  common  assemblage  for  (actinolite)-epidote-chlorite-plagioclase group  rocks,  on  the  other  actinolite-epidote-chlorite-albite amphiboles  or  two amphiboles  Antler  rocks  is  hornblende-  (tquartz i c a l c i t e imagnetite).  hand,  show  assemblages  ( iquartz i c a l c i t e ) ; occur,  but  one  Takla  composed  occasionally,  of  zoned  i s most c e r t a i n l y  primary  mesoscopic t e x t u r e s  mostly  ( r e l i c t igneous). The Takla Group of  primary  volcaniclastic  limited to mild typical  r o c k s show a wide  foliations,  assemblage  origin,  range  of  and superimposed  secondary t e x t u r e s are  o c c a s i o n a l f o l d i n g , and l o c a l i z e d m y l o n i z a t i o n .  (act-ep-chl-ab)  occurs  Page 93  as very f i n e  growths t h a t  The  barely  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. B r i t i s h Coluwbia disrupt  many  primary  features.  u b i q u i t o u s occurrence calcite  of c h l o r i t e ,  growth  of  new  amphibole  (actinolite),  and some v e i n i n g o f q u a r t z , e p i d o t e ,  and/or  r e p r e s e n t t h e e x t e n t t h a t metamorphism has a f f e c t e d t h i s u n i t .  The A n t l e r effects  The  (having  microscopic (actinolite,  rocks, lost  on t h e  most  scales.  or  The  hornblende,  other all  S2  and  hand,  display  primary  foliation  rarely  predominately  features)  on both  is  by  other  formed  amphiboles  metamorphic  mesoscopic  chlorite, occur),  and  amphibole  and  epidote  ( ± f e l s i c s ) ( F i g u r e 4 5 ) ; c h l o r i t e has u s u a l l y grown i n p l a n a r masses, t h e amphiboles can occur as random s p l a y s o r n e a r - p e r f e c t l y a l i g n e d (producing a very good l i n e a r fabric)  w i t h i n planar  zones,  and t h e e p i d o t e  (± f e l s i c s )  forms f i n e t o medium  g r a i n e d g r a n o b l a s t i c masses w i t h an o v e r a l l l e n s o i d appearance ( F i g u r e 4 5 ) . prismatic nature of feldspar  (and sometimes q u a r t z )  i n t h e more f e l s i c  The  Antler  s u b u n i t s a l s o a i d s i n t h e d e f i n i t i o n o f t h e S2 f o l i a t i o n . The g e n e r a l d i s t r i b u t i o n o f assemblages i n t h e A n t l e r across t h e area has been summarized i n F i g u r e 46.  T h i s map shows a s u b d i v i s i o n o f these assemblages  into  population  three mineral  assemblage  secondary amphibole, 2 ) a c t i n o l i t e , and 3 )  oligoclase  coexisting  with  groups:  1)  actinolite  hornblende, e p i d o t e , and a l b i t e epidote.  This  breakdown i s  as t h e  only  coexisting,  based  on two  generalized reactions: a l b i t e + epidote = oligoclase + epidote c h l o r i t e decreasing/hornblende which are a l s o shown on F i g u r e 46. Q u a r t z o - f e l d s p a t h i c Type). Moody e t a l . (1983) w i t h  increasing  The f i r s t r e a c t i o n has been discussed above (see  The second r e a c t i o n has r e c e n t l y been looked a t by  r e l a t i o n t o the t r a n s i t i o n from the greenschist f a c i e s t o  t h e a m p h i b o l i t e f a c i e s (compare F i g u r e 37 and F i g u r e 4 7 ) . F i g u r e 47 summarizes  Page 94  Actinolite w i t h no 2ndary Hornblende HornblendTe''''*--'^^  Ili-Gkl-Rk-Cc-HBbi-Otz ^•ds)-Rct-Clz-Cbl-Qtz  \  Cc-Qt2-Ep-Chl-ib-H»M Na-Plag w i t h Ep IlzrEp-Para-M-Chl-Bio-HnM-Qtz  Ep-Jin-Bio-01i|-Chl-Otz  <Vtz>-B«sc-li«-Chl-Ep-0lii2 fc^  Ca-Plag""""  to  (Rspar)-Ps-Talc-Otz-ank Actinolite 5 w i t h no » 2ndary Hornblende  .  Ep-Iln-CM-Cc-Ctz-OltB  <Ep)-lgt-<nasc)-Cfel-(Cc^-Otz-ib Hornblende \ Actinolite \ Ca-Plag V Qtz-ipt-Ep-Cbi-cc-tb \ with E p i d o t e ^ -4k— Na-Plag \ with E p i d o t e \ Cbl-Ep-Otz-Cc-«b  \  Ce-ttl-Ep-ib-HabiVbet -  ^  SCALE  \  _^laba-lb-Ckl-Otz-Ep  Cc lBt-QU-m-Inb--B|Oi _^. r  L  ,«^__Cbl-Felsic-E.-i.* l/Rct  --^V^^.  3T  1  CBio)-Ep-Hib«-lQt-Oil-Ot H bi-Ctal-Ep-Otz\ l|t-Cc-Chl-Ep-Hab«/tct-Otz CM-Cc-Otz-li-Ep l|t-Hnbtf/lct-Chl-Ep-Otz-B» 2  Figure  46 - The d i s t r i b u t i o n  of mafic  B  assemblages f o r  shown s e p a r a t e a s s e m b l a g e s on e i t h e r (hornblende  in  kilometers  and o l i g i o c l a s e  in)  side  the Antler of  two  discussed  Formation;  reactions  in the  text  surfaces  structural Geology of Part of the crooked Lake Area, Quesnel Highlands. British Colunbia t h e i r r e s u l t s as a p l o t o f p r e s s u r e - t e m p e r a t u r e spaoe; t h e t r a n s i t i o n zone o u t l i n e d shows t h e above r e a c t i o n s on t h e low temperature s i d e and a second r e a c t i o n : c h l o r i t e out on t h e h i g h temperature s i d e .  The A n t l e r r o c k s have c l e a r l y not l e f t t h i s zone (as  t h e c h l o r i t e found across t h e area i s not a l t e r a t i o n g r o w t h ) , but must have reached f a r enough t o pass any p o s s i b l e zone o f two c o e x i s t i n g f e l d s p a r s . The s u r f a c e s o u t l i n e d i n F i g u r e 46 are assumed t o have t h e same general o r i e n t a t i o n as t h e major c o n t a c t s ; t h e i r r e p e t i t i o n f r o m east t o west would suggest t h a t t h e y f o r m f o l d e d shapes w i t h e s s e n t i a l l y a D3 f o l d a x i s o r i e n t a t i o n . r e a c t i o n s a s s o c i a t e d w i t h these s u r f a c e s a r e , f o r t h e most p a r t ,  Since t h e  independent o f  pressure t h e core o f these f o l d e d shapes r e p r e s e n t s a t h e r m a l maximum f o r t h e M2 metamorphic episode.  Temperatures can be expected t o have been i n t h e range o f  500°-575° C a t pressures f r o m 4 - 7 k b a r s . Calcareous Type Rocks o f t h i s c o m p o s i t i o n may be composed and/or  any combination o f  calcsilicates  of  (e.g.  calcite  talc,  and/or  tremolite,  dolomite diopside,  w o l l l a s t o n i t e ) dependent on t h e amount o f magnesia and s i l i c a i n t h e o r i g i n a l r o c k ; s i g n i f i c a n t amounts o f alumina and p l a g i o c l a s e form.  Usually,  and dolostones, overlap in  to  will  form as w e l l ;  these r o c k s are  allow  minerals  derived  and c a l c a r e o u s and  from limestones,  dolomitic  sediments,  i s p o o r l y r e p r e s e n t e d i n t h e Crooked  a n k e r i t i c r i c h assemblages are p r e s e n t quartz-musc-calcite  hornblende,  epidote,  i f i r o n i s present t h e carbonate a n k e r i t e  i s unavoidable w i t h c a l c a r e o u s m a f i c igneous rocks,  general,  bands o f  the  occur  i n the  Antler  s i l i c e o u s limestones but  degree  of  This type,  calcareous and  the p h y l l i t e ,  i n t h e Snowshoe Formation.  Page 96  some  as w e l l .  Lake u n i t s ; and  might  whereas  structural ecology of Part of the Crooked Lake Area, Quesnel Highlands. B r i t i s h Coluwbia  10-, Sources CHL*PARA-»QTZ=CTD+AB*VAP (CHINNER, [1967],H0SCHEK, [1969])  8.  CHL*HU$C=STAUR+BI0*QTZ*H20 (HOSCHEK, [1969]) CTD*ASK=STAUR*QTZ STAUR+QTZ=C0R0*ASK (RICHARDSON, [1968],TURNER, [1981]) STAUR+QTZ=GN+ASK HUSC*QTZ=ASk>KSPAR (HELGESON et al, [1978],TURNER, [1981]) ASK EQUILIBRIA (HOLDAWAY, [1971],TURNER, [1981]) •STIPLED AREA' (H00DY et a l , [1983])  7v.  6.  S CO  o t CL  o CM  X  4-  2_  1-  I  I  I  I  100  I  I  I  I  200  I  I  I  I  300  i  I  F i g u r e 47 - Pressure temperature p l o t o f Lake q u a r t z o - f e l d s p a t h i c ,  I  400 T,° C  I  I  I  500  I  i  I  600  i  i  i  I  700  I  I  e q u i l i b r i a r e l e v a n t t o t h e Crooked  pelitic, Page 97  and m a f i c composition types  800  Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunpla  By f a r t h e most obvious calcareous u n i t s occur i n t h e Snowshoe f o r m a t i o n where qtz-musc-cc and zo-plag-musc-cc  assemblages occur.  P h y l l i t e and A n t l e r assemblages i n c l u d e m u s c - q t z - c h l - a n k ,  I n t h e Crooked Lake graph-chl-ank-musc-qtz,  and l e s s commonly a n k - p y - e p - c c - a b - q t z . U n f o r t u n a t e l y , these assemblages are common over most o f t h e g r e e n s c h i s t and i n t o t h e a m p h i b o l i t e f a c i e s so are not p a r t i c u l a r l y diagnostic.  F i g u r e 48  -  Coarse and very f i n e banding t e x t u r e i n p e l i t i c marble o f Snowshoe t h a t o u t l i n e s S2 f o l i a t i o n ( c r o s s - n i c o l s , X12.5,L0C-RZ11)  I n g e n e r a l , these u n i t s are g r a n o b l a s t i c w i t h a f o l i a t i o n developing where muscovite or c h l o r i t e i s abundant. p a t t e r n occurs i n Domain I f o l i a t i o n i n t h e Snowshoe.  only  The o n l y i n s t a n c e of a d e p a r t u r e from t h i s  where c r y p t o c r y s t a l l i n e bands p a r a l l e l t h e main S2 I n t h i n s e c t i o n ( F i g u r e 4 8 ) , these bands are seen t o  c o n s i s t of very f i n e c a l c i t e and minor muscovite and f i n e rounded g r a i n s o f q u a r t z ;  Page 98  Structural eeology of Part of the crooked Lake Area, Quesnel Highlands. British Coluwbia next t o these bands t h e main rock t y p e i s  coarse c a l c i t e t h a t  shows abundant  d e f o r m a t i o n t w i n n i n g and k i n k i n g . U l t r a b a s i c Type This  composition  t y p e i s c h a r a c t e r i z e d by t h e  occurrence o f a n t i g o r i t e ,  talc,  ultrabasic  are  igneous  u n i t was found  rocks  anthophyllite, t h e usual  absence  and o t h e r  parentage.  o f f e l d s p a r and  magnesian  minerals;  A serpentinized p e r i d o t i t e  i n the A n t l e r Formation; r e p o r t s of s i m i l a r u n i t s i n the  o f t h i s area (R.B. Campbell (1963) and K.V. Campbell  Snowshoe  (1971)) most l i k e l y r e f e r t o  s t r u c t u r a l i n f o l d s o f t h e A n t l e r i n t o t h e Snowshoe. The c h a r a c t e r i s t i c p r i m a r y assemblage o f t h i s u n i t i s o p x - o l and s e c o n d a r i l y serp  and cc  occur  as e x t e n s i v e  veining  across,  between,  and w i t h i n  grains.  Serpentine has developed f r o m t h e primary rock as i t grows even along orthopyroxene cleavage planes, but t h e c a l c i t e has probably been i n t r o d u c e d from t h e s u r r o u n d i n g rocks.  The o v e r a l l t e x t u r e i s g r a n o b l a s t i c w i t h a h i g h degree o f f r a c t u r i n g . Metamorphism and Deformation  A d e f i n i t e r e l a t i o n s h i p e x i s t s between t h e metamorphic f e a t u r e s d e s c r i b e d above and those o f t h e t h r e e d e f o r m a t i o n a l events.  F i g u r e 49 o u t l i n e s t h e r e s u l t s o f m i c r o s c o p i c  examination o f d e f o r m a t i o n a l f e a t u r e s ;  t h i s f i g u r e i s a composite t a k e n from t h e  m i n e r a l vs. d e f o r m a t i o n c h a r t s shown i n Appendix A f o r i n d i v i d u a l rock samples.  The  e a r l i e s t m i n e r a l growth (M1) i s r e s t r i c t e d t o t h e o l d e s t u n i t s and c o n s i s t s o f r e f o l d e d f e a t u r e s and/or f e a t u r e s t h a t are e a r l i e r t h a n t h e D2 d e f o r m a t i o n . U n f o r t u n a t e l y ,  a  p o s i t i v e connection was never made between mesoscopic D1 elements and these metamorphic f e a t u r e s ; t h i s u n c e r t a i n t y i s r e f l e c t e d i n F i g u r e 49 f o r many o f t h e m i n e r a l s t h a t may r e p r e s e n t D1 f e a t u r e s  Page 99  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia  F i g u r e 49  - Summary o f m i n e r a l growth r e l a t i v e t o d e f o r m a t i o n f e a t u r e s composed f r o m diagrams o f i n d i v i d u a l samples and t h i n s e c t i o n s d e s c r i b e d i n  Page 100  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia transposed p a r a l l e l S2 i n t h e lower two u n i t s . The D2 episode corresponds w i t h t h e g r e a t e s t amount o f m i n e r a l growth i n a l l u n i t s ( t h e M2 e v e n t ) and t h u s r e p r e s e n t s a c u l m i n a t i o n i n t h e metamorphic h i s t o r y o f t h e area.  A s m a l l amount o f muscovite and  c h l o r i t e growth seen along l a t e r S3 cleavages l i n k s t h e t h i r d event (M3) t o t h e D3 deformation. Evidence f o r t h e M1 event c o n s i s t s o f r e f o l d e d b i o t i t e f o l i a t i o n s and h i g h angle i n c l u s i o n s w i t h i n K - f e l d s p a r .  Both o f these m i n e r a l s are common a s s o c i a t e s  o f a m p h i b o l i t e f a c i e s metamorphism and i f indeed t h i s e a r l y event had reached such a high l e v e l  o f temperature  extensively affected.  and pressure t h e two lowest u n i t s should have been  A s t r o n g and enduring h i s t o r y f o r t h e 02 episode i s b e l i e v e d ,  by t h e present a u t h o r , t o account f o r t h e t o t a l o b l i t e r a t i o n o f e a r l i e r f e a t u r e s . Some degree o f u n c e r t a i n t y about t h e h e i g h t reached by t h i s event e x i s t s because K-f e l d s p a r may e q u a l l y or more l i k e l y be a primary phase. A clear  p i c t u r e has evolved concerning c h a r a c t e r i s t i c s  Extensive m i n e r a l growth i n a l l u n i t s  o f t h e H2 event.  has l a r g e l y masked o r i g i n a l f e a t u r e s causing  t h e development o f very dominant secondary f a b r i c s .  M i n e r a l e q u i l i b r i a f r o m two o f  t h e f i v e composition groups have a l l o w e d maximum temperatures t o be estimated and t h e l a t e s t e x i s t i n g temperature g r a d i e n t f i e l d s t o be understood; temperatures o f 500° -575° C a t pressures f r o m 4 - 7 kbars were d e r i v e d f r o m c h l o r i t o i d e q u i l i b r i a , and t h e t r a n s i t i o n s f r o m a o t i n o l i t e t o hornblende assemblages and from a l b i t e - e p i d o t e t o o l i g i o c l a s e - e p i d o t e assemblages.  The c o n f i g u r a t i o n o f s u r f a c e s a s s o c i a t e d w i t h  t h e l a s t two t r a n s i t i o n e q u i l i b r i a suggest t h a t temperature g r a d i e n t s  increase  toward t h e s o u t h e a s t ; t h e i r f o l d e d f o r m most l i k e l y developed a f t e r t h e D2 episode as a r e s u l t o f D3 f o l d i n g .  Page 101  structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Colunbia *wTOT sssssss sssssss sssssss sssssss sssssss sssssss sssssss sssssss sssssss sssssss wsssss sssssss sssssss sssssss sssssss \\\\\\\  /  /  /  c c c c c  /  SSSSSSS SSSSSSS  sssssss SSSSSSS  sssssss sssssss  SSSSSSS' SSSSSSS' SSSSSSS \\\\\\\ SSSSSSS SSSSSSS  sssssss sssssss sssssss sssssss sssssss sssssss www www ' "WW WW .WW WW ssss .WW .WW .WW sssss ssss WW WW ssss  /  /  /  /  ASS  ss / / / / ss s s s WW .WW .WW www .www sssssss sssssss sssssss SSSSSSS sssssss www\ sssssss sssssss www\ ww\w wwws wwws ssss / / / / WW .WW WW - w\ s s\ s\ / / / /  NESEIT III CMFianiTIM  I  IS I r l t t l e Event (S5 Fractariei, ctanei, lf u l t i e i )  rnii—  I I  (S4 FricUre Cletviie)  13 Fallini (S3 Spicei Cleiviie)  12 Faltfiii/Tkmtiai (S2 Preiiieit Faliatiea/aeavaie)  - ~ i  Cretkel Lake Pkillite Eireki Qaartzlte  s s s s /  /  /  /  f  Sioislne  X  f  X  t  •>ww ww w sss w ws sws \ wwws t f f f sssssss sssssss wsssw sssssss sssssss sssssss sssssss S f * / sssssss sssssss sssssss sssssss -ssssss sssssss ssssssv  arsca l i r a METAMORPHISM F i g u r e 50  -  II Falllii  I  \  V<SI Fallttloa) J  ss s s s . ss / / / /  HUM.  3 I  Takla Creep  L  >f\SSSS  J  B4 FtMii  l  \  J  ••tier Ferittlei  Saeeskee Ferietlei  TIME  DEFORMATION  R e l a t i v e t i m i n g r e l a t i o n s between metamorphism and deformation and t e n t a t i v e c o r r e l a t i o n w i t h t h e a b s o l u t e t i m e s c a l e ; metamorphic scale shows t h r e e generalized grades: burial, greenschist, amphibolite  Page 102  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Pressure e s t i m a t e s are r a t h e r wide, compared t o those o f temperature, b u t no s u i t a b l e r e a c t i o n s t o determine pressure were observed.  I t may be assumed based on  p r e v i o u s f i n d i n g s i n t h e r e g i o n (K. V. Campbell 1971, F l e t c h e r 1972) t h a t a t y p i c a l B a r r o v i a n t r a j e c t o r y i s c h a r a c t e r i s t i c o f t h i s event ( p r e s s u r e o f about 4 k b a r s ) ; t h e m i n e r a l assemblages r e p r e s e n t e d would be a s s o c i a t e d w i t h t h i s t y p e o f  'P-T'  trajectory. F i g u r e 50 shows a summary o f t h e metamorphic/deformational deduoed.  relationships  I n t h i s diagram r e l a t i v e t i m i n g o f t h e d i f f e r e n t events i s shown.  Three  d i f f e r e n t packages are considered t o have oocupied t h i s area over t i m e (shown by l e f t - m o s t bar graphs) and are shown w i t h d i s t i n c t metamorphic h i s t o r i e s ( s h o w n as t h e w i d t h o f bar graphs f r o m l e f t - h a n d s i d e ) .  The Snowshoe i s shown as a separate  package e x p e r i e n c i n g b u r i a l metamorphism b e f o r e t h e t i m e o f A n t l e r emplacement, not on t h e b a s i s o f evidence t o t h e e f f e c t b u t simply t o i l l u s t r a t e t h a t t h e o r i g i n o f t h e two u n i t s were d i s t i n c t f r o m one another; f o l l o w i n g t h a t t i m e these two u n i t s are shown j o i n e d and t o g e t h e r experienced t h e M1 episode w h i l e 01 f o l d i n g took place. point  These u n i t s remain b u r i e d w h i l e t h e upper u n i t s were emplaced and from t h a t onward t h e i r  common h i s t o r y  shows two f i n a l  episodes f o l l o w e d by two l a r g e l y d e f o r m a t i o n a l events.  Page 103  metamorphic/  deformational  Structural fieology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia CONCLUSION The  Crooked  Lake map-area l i e s a t t h e boundary between  g e o t e c t o n i c p r o v i n c e s o f t h e Canadian h i s t o r y a t l e a s t s i n c e t h e mid  Jurassic.  p l a t f o r m a l sequence o f f t h e coast to  e a r l y Phanerozoic  mid-Phanerozoic  Cordillera  time.  of  that  have  two  shared  distinct a common  The b e l t s t o t h e east o r i g i n a t e d as a  t h e N o r t h American c r a t o n from  Proterozoic  To t h e west t h e t e r r a n e s show evidence o f  o r i g i n i n an oceanic  setting.  a  The two r e g i o n s c o u l d e a s i l y have  developed thousands o f k i l o m e t e r s f r o m each o t h e r . The rocks Antler 1971;  of  e a r l i e s t recorded i n t e r a c t i o n s between u n i t s a t Crooked Lake the  Kaza Group,  Formation,  that  Montgomery,  local  p l a t f o r m a l r e p r e s e n t a t i v e s , and a u n i t ,  i s believed t o  1978).  be a s e c t i o n o f  ocean c r u s t  of  over  Thrusting  m y l o n i t i c t e x t u r e s t o form  at  involved  the  Antler  the  the  (Campbell, Kaza caused  t h e c o n t a c t between t h e u n i t s ; t h e e a r l y phase o f  f o l d i n g recorded i n both rock t y p e s c o u l d have accompanied t h i s t h r u s t i n g episode, though  it  is  also  possible  that  these  features  record  events  that  pre-date  t h r u s t i n g , t h u s being unique t o t h e i n d i v i d u a l u n i t s . The remaining u n i t s were i n t r o d u c e d i n t o t h e area perhaps by t h r u s t i n g , well; of the  t h i s i n t e r p r e t a t i o n seems more reasonable t h a n possible  rocks t o t h e west.  simple  deposition  as  because  a l l o c h t h o n o u s a s s o c i a t i o n these upper u n i t s have w i t h t e r r a n e Thrusting  would  explain truncation  of  t h e Eureka Q u a r t z i t e  as w e l l as t h e s t r o n g m y l o n i t e development a t t h e t o p o f t h e p h y l l i t e . The age o f t h e Crooked Lake P h y l l i t e i s a s i g n i f i c a n t problem i n terms o f t h e regional picture. belt t o the north  C o n s i d e r i n g t h e abundance o f s l a t y and  northeast,  t h e p h y l l i t e s w i t h these  it  rock t y p e s  in  t h e Omineca  i s understandable t h a t e a r l y workers l i n k e d  r o c k s (Campbell and T i p p e r ,  Page 104  1971).  The present author.  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Coluwbia i n f a c t , cannot help but n o t i c e t h e s i m i l a r i t y between s t r a t i g r a p h y o f t h e Crooked Lake P h y l l i t e by  Struik,  and u n i t s such as t h e P a l e o z o i c Black S t u a r t (1981).  Such c o r r e l a t i o n s ,  known t o date t h a t suggest Crooked  Lake p h y l l i t e  elevation  exposures  The  flexural  an upper  with will  its  though, oppose t h e  Triassic occasional  one day y i e l d t h e  folding  Formation as  recorded i n  the  age.  It  limy  fossil  collections  i s believed  horizons  fossils  described  and  that good  high  t o date t h i s u n i t .  phyllite  could  be r e l a t e d t o an  emplacement process and seems t o have occurred w h i l e t h e m a t e r i a l was s t i l l The c o n t i n u i n g d e f o r m a t i o n o o i n c i d e d  the  wet.  w i t h an i n c r e a s e o f metamorphic grade ( t h a t  probably f o l l o w e d a B a r r o v i a n t r a j e c t o r y t o t h e boundary between t h e g r e e n s c h i s t and a m p h i b o l i t e metamorphic f a c i e s ) ; temperatures t h e response o f t h e characteristically similar  i n t u r n , at progressively higher  rock  in style.  u n i t s changed  higher  so t h a t f o l d s became more  Abundant s h e a r i n g o f t h e  along p r e v i o u s l y formed a x i a l p l a n a r f a b r i c s t o  and  u n i t s took  place  accommodate t h e s t r a i n w i t h i n t h e  rock mass. The next phase saw folds.  By  this  time,  the  metamorphic  had changed t o a more f l e x u r a l event ( w . r . t .  onset o f d e f o r m a t i o n grade  style.  forming  had decreased  The c o p l a n a r i t y  westerly  verging  and a c c o r d i n g l y  folds  (and c o l i n e a r i t y ) o f  t h e p r e v i o u s e v e n t s ) has made s e p a r a t i o n  of  these  this  f o l d s from  e a r l i e r minor f o l d forms d i f f i c u l t or i m p o s s i b l e i n o e r t a i n areas ( i . e . Domain I , southwest involved  of  Crooked L a k e ) ;  i t i s b e l i e v e d t h a t much  i n t h i s phase would be used t o  of  the s t r a i n  energy  t i g h t e n e x i s t i n g forms r a t h e r t h a n c r e a t e  new ones.  Page 105  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia The to  f i n a l f o l d i n g phase w i t h i t s f o l d forms ( i n c l u d i n g k i n k i n g ) t r a n s v e r s e  t h e p r e v i o u s ones r e p r e s e n t s a s i g n i f i c a n t d e p a r t u r e from t h e t y p e o f mechanism  o p e r a t i n g i n t h e r e g i o n up t o t h i s t i m e . Subsequently, b r i t t l e d e f o r m a t i o n ( f r a c t u r i n g and f a u l t i n g )  with a possible  t r a n s c u r r e n t c o n f i g u r a t i o n a f f e c t e d t h e Crooked Lake u n i t s . The l a t e r h i s t o r y o f t h e area, as evidenced f r o m nearby r e g i o n s , i n c l u d e t h e 100 Ma i n t r u s i v e s o f Campbell and T i p p e r , (1970), Eocene v o l c a n i c a c t i v i t y , Miocene t o Pliocene plateau basalts,  and most r e c e n t l y an extended p e r i o d o f  g l a c i a l a o t i v i t y ( T i p p e r , 1971).  Page 106  cyclical  Structural Geology of Part of the Crooked Lake Area. 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Experimental  determination  of  the  muscovite  +  quartz  s t a b i l i t y w i t h Pn?n < P t n t a i . Am. J . S c i . , v.272, p.946-958. Marshal, 1927.  Clearwater Lake Map Area,  i n Geol. Surv. Can., Sum. Rept. 1927,  P a r t A, p.45-46. Mereu, R.F., S.C. Majumdar, and R.E. White, 1977!  The s t r u c t u r e o f t h e c r u s t and  upper mantle under t h e h i g h e s t ranges o f t h e Canadian Rockies f r o m a seismic r e f r a c t i o n survey. Can. J . E a r t h S c i . , v. 14, p. 196-208. Miyashiro, A.,  1973.  Metamorphism and metamorphic b e l t s . John Wiley & Sons, New  York, 492p. Moody, J . B . , D. Meyer, and J . E . J e n k i n s ,  1983.  Experimental c h a r a c t e r i z a t i o n o f  t h e g r e e n s c h i s t / a m p h i b o l i t e boundary i n mafic systems. Am. J . S c i . , v.283, p.48-92. Monger, J . W. H., 1977. their  bearing  Upper P a l e o z o i c r o c k s of t h e Western Canadian C o r d i l l e r a and on  Cordilleran  evolution.  p.1832-1859.  Page 109  Can.  J.  Earth  Sci.,  v. 14,  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Columbia Monger,  J . W.H.  and W. W.  Hutohinson,  1971.  Metamorphio  map o f  the  Canadian  C o r d i l l e r a . Geol. Surv. Can., Paper 70-33. Monger, J . III). H., R. A. P r i c e , and D. J . Tempelman-Kluit, 1982.  T e c t o n i c a c c r e t i o n and  t h e o r i g i n o f t h e two major metamorphic and P l u t o n i c w e l t s i n t h e Canadian C o r d i l l e r a . Geology, v. 10, p. 70-75. Montgomery, S . L . , 1978. area.  Cariboo  S t r u c t u r a l and metamorphic h i s t o r y o f t h e Lake Dunf ord map  Mountains,  southeastern  Canadian  British  Columbia:  Cordillera,  Ophiolite  unpublished  obduction  MSc  thesis,  in  the  Cornell  U n i v e r s i t y , 170p. Murphy, D.C.,  and J.M. Journeay,  Cariboo  Mountains,  1982.  southern  S t r u c t u r a l s t y l e i n t h e Premier Range,  British  Columbia:  Preliminary  Results,  in  Current Research, P a r t A, Geol. Surv. Can., Paper 82-1 A, p.289-292. Murphy, D.C., and C. J . Rees, 1983. Cariboo Mountains,  S t r u c t u r a l t r a n s i t i o n and s t r a t i g r a p h y i n t h e  B r i t i s h Columbia,  i n C u r r e n t Research,  P a r t A, Geol.  Surv. o f Can., Paper 83-1 A, p.245-252. O k u l i t c h , A . V . , 1984.  The r o l e o f t h e Shuswap Metamorphic Complex i n C o r d i l l e r a n  t e c t o n i s m : a review.  Can J . E a r t h S c i . , v . 2 1 , p. 1171-1193.  P e l l , J . and P.S. Simony, 1982.  Hadrynian H o r s e t h i e f Creek Group c o r r e l a t i o n s i n  t h e Southern Cariboo Mountains, B r i t i s h Columbia, i n C u r r e n t Research, P a r t A, Geol. Surv. Can., Paper 8 2 - 1 A, p.305-308. P e t t i J o h n , F . J . , P.E. P o t t e r , and R. S i e v e r , 1972.  Sand and Sandstone.  Springer-  V e r l a g , New York, 622p. Pigage,  L.C.,  margin  1977. of  Rb-Sr dates f o r  the  g r a n o d i o r i t e i n t r u s i o n s on t h e  Shuswap Metamorphic  Complex,  Cariboo  northeast  Mountains,  British  Columbia. Can J . E a r t h S c i . , v . 1 4 , p. 1690-1695. Ramsay, J . G., 1967.  F o l d i n g and F r a c t u r i n g o f Rocks. McGraw-Hill, New York, 568p.  Rees, C . J . ,  Western margin o f t h e Omineca B e l t a t Quesnel Lake,  1981.  Columbia,  in  Current  Research,  Part  A,  Geol.  Surv.  Can.,  Paper  British 81-1A,  p.223-226. Rees,  C. J . ,  and F.  Ferri,  1983.  Omineca-Intermontane  Belt  A k i n e m a t i c study o f m y l o n i t i c tectonic Page 110  boundary  in  rooks i n t h e  east-central  British  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Columbia,  i n C u r r e n t Research, P a r t B, Geol. Surv. o f Can., Paper 83-1B,  p.121-125. Ross, J . V . , 1981.  A geodynamic model f o r some s t r u c t u r e s w i t h i n and adjacent t o t h e  Okanagan V a l l e y , B r i t i s h Columbia. Can. J . E a r t h S c i . , v. 18, p. 1581-1598. Spry, A . , 1969. Struik,  L.C.,  Hetamorphio t e x t u r e s . Pergammon Press, Oxford, 352p. 1981.  Snowshoe Formation,  c e n t r a l B r i t i s h Columbia,  in  Current  Research, p a r t - A , Geol. Surv. Can., Paper 81-1 A, p.213-216. S t r u i k , L.C., Cariboo  1981.  A r e - e x a m i n a t i o n o f t h e t y p e area o f t h e O e v o n o - H i s s i s s i p i a n  Orogeny,  central  British  Columbia.  Can.  J.  Earth  Sci.,  v. 18,  p.1767-1775. Struik,  L.C.,  1982.  Snowshoe Formation  (1982),  c e n t r a l B r i t i s h Columbia,  in  Current Research, p a r t - B , Geol. Surv. Can., Paper 82-1B, p. 117-124. S u t h e r l a n d Brown, A.,  1957.  Geology o f t h e A n t l e r Creek area. Cariboo D i s t r i c t ,  B r i t i s h Columbia. B. C. Dept. o f Mines, B u l l 38. S u t h e r l a n d Brown, A . ,  1963  Geology o f t h e Cariboo R i v e r area, B r i t i s h Columbia.  B. C. Dept. o f Mines and P e t r o l . Res., B u l l . 47. Tipper, H. W., 1971. Sci., Tipper,  M u l t i p l e g l a c i a t i o n i n c e n t r a l B r i t i s h Columbia. Can J . E a r t h  v . 8 , p.743-752.  H.W., R.B. Campbell, G.C. T a y l o r ,  and D.F. S t o t t ,  1979.  Parsnip R i v e r ,  B r i t i s h Columbia (Sheet 9 3 ) . Geol. Surv. Can., Map 1424A ( 1 : 1 , 0 0 0 , 0 0 0 ) . T r a v e r s , W.B., 1978.  Overturned N i c o l a and A s h c r o f t s t r a t a and t h e i r r e l a t i o n t o  Cache Creek Group, southwestern Intermontane B e l t , B r i t i s h Columbia. Can. J . E a r t h S c i . , v. 15, p.99-116. Turner,  F.J.,  aspects.  1981.  Metamorphic  petrology:  Mineralogic,  field,  and  tectonic  McGraw-Hill, New York, 526p.  Uglow, W.L., 1922.  Geology o f t h e N o r t h Thompson v a l l e y map area, B r i t i s h Columbia.  Geol. Surv. Can., Sum. Rept. 1921, P a r t A, p.76-106. Wheeler, J . O . , 1967. T e c t o n i c s i n Canadian Upper Mantle Report, G. S.C. Paper 6 7 - 4 1 , p.4-30. Wheeler, J . O . , 1970. Cordillera.  Summary and D i s c u s s i o n , S t r u c t u r e o f t h e Southern Canadian  G.A.C. Sp. Paper #6.  Page 111  S t r u c t u r a l fienlow of Part at th» Crinilwri  l a l t P *T»a  Qiipgnpl HiflhlaniU, B r i t i s h  finliwhia  APPENDIX A  T h i s s e c t i o n summarizes rock d e s c r i p t i o n data f o r t h e f i v e u n i t s a t Crooked Lake.  Host of t h e i n f o r m a t i o n presented i s from e x t e n s i v e m i c r o s c o p i c examination  o f t h i n s e c t i o n s c u t f r o m samples t a k e n i n t h e f i e l d and a few d e s c r i p t i o n s are taken from m i n e r a l o g i c a l and t e x t u r a l data recorded i n t h e f i e l d .  The f o l l o w i n g  f o r m a t was used e x c l u s i v e l y : Colour  Weathered and f r e s h s u r f a c e s were examined  Grain Size  The standard used was t h e one commonly used f o r sandstones t a k e n f r o m P e t t i j o h n e t a l , ( 1 9 7 2 ) - very f i n e = . 0625 - . 125mm f i n e = . 125 -.25mm medium = . 25 - . 50mm coarse = . 50 - 1.00mm very coarse = 1.00 - 2.00mm measurements i n t h i n s e c t i o n were made by comparing g r a i n s t o known f i e l d - o f - v i e w diameters. E s t i m a t i o n s were made i n t h e field.  Mineralogy  E v a l u a t i o n o f m i n e r a l percentages i s based on two or more t h i n s e c t i o n s (where p o s s i b l e ) cut at d i f f e r e n t o r i e n t a t i o n s through the rock so t h a t t h e whole volume o f rock i s considered. Ranges g i v e n attempt t o account f o r t h e f i n e scaled h e t e r o g e n e i t y o f t e n encountered (banding, veining, variable sorting).  Texture  F i r s t , t h e o v e r a l l t e x t u r e o f t h e rock i s d e s c r i b e d , f o l l o w e d by i m p o r t a n t m i c r o s c o p i c features of constituent minerals.  Assemblages  C o e x i s t i n g phases are given f o r t h e rock  Name  A name i s g i v e n t o t h e rock  History  I n t h e case o f most o f t h e data a r e l a t i v e dating diagram has been constructed associating growth of minerals with mesocopic def o r m a t i o n a l elements  The u n i t s d e s c r i b e d i n t h i s appendix c o r r e l a t e e x a c t l y t o those shown on P l a t e 4, t h e S t r u c t u r a l / S t r a t i g r a p h i c  Sections;  t h e order used here i s ,  r e l a t i v e t o each l i t h o l o g i c u n i t ( i . e . A f o r Snowshoe, B f o r A n t l e r ,  first,  e t c . ) and,  second, r e l a t i v e t o i n c r e a s i n g s e c t i o n number (e. g. Snowshoe has r e p r e s e n t a t i v e s i n Sections 1, 4, & 5 ) .  Page 112  structural Qeologv of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia SNOtSHOE FORMATION [A1a] {RZ10, RZ11}  Colour Grain  weathered - yellow-brown t o t a n f r e s h - t a n t o grey-green Size  Mineralogy  Textures  f i n e t o medium w i t h coarse b i o t i t e andgarnet, coarse q u a r t z v e i n i n g and i n t e r l a m i n a t e d very f i n e e l a s t i c s and opaques Quartz Muscovite Chlorite B i o t i t e / F e Oxide  60-90* 15-08% 20-00% 05-02%  Accessory Garnet Tourmaline  F i n e l y l a m i n a t e d t o f i n e l y l a y e r e d (mm- dm s c a l e ) ; compositional layering of p e l i t i c - f e l s i c s c h i s t and minor q u a r t z i t e | | S2 f o l i a t i o n and g e n e r a l l y d i s c o n t i n u o u s ; m y l o n i t e banding a l s o | | S2 f o l i a t i o n . S2 f o l i a t i o n ranges f r o m a spaced cleavage i n f e l s i c subunits t o a penetrative f o l i a t i o n i n p e l i t i c s u b u n i t s and has been c r e n u l a t e d by a t l e a s t one l a t e r cleavage. Wavy and u n d u l a t i n g f o r m . Packages show medium t o t i g h t f o l d i n g Micas - d i m e n s i o n a l - p r e f e r r e d o r i e n t a t i o n d e f i n e s S2 f o l i a t i o n and p o s s i b l e e a r l i e r fabric(s)  Assemblages  Chl-Musc-Qtz Bio-Musc-Chl-Qtz Musc-Qtz  Name  Bio-Chl-Musc-Qtz S c h i s t  Qtz Muse Bio Chl Augen Feld Mylonitic Banding  D1  D2  Units A1a. A1b. A1c ' Page 113  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia  [A2a] {RZ8, RZ11}  Colour  weathered - dark yellow-brown t o yellow-orange f r e s h - r u s t y , l i g h t grey t o w h i t e  G r a i n Size  two i n t e r l a y e r e d v a r i e t i e s : -coarse c r y s t a l l i n e w i t h < 5* f i n e s at g r a i n boundries - v e r y f i n e c r y s t a l l i n e w i t h < 5% coarse supported by m a t r i x  Mineralogy  Calcite Muscovite Quartz  Textures  Medium l a y e r e d w i t h f e l s i c - p e l i t i c s c h i s t (dm t o m s c a l e ) ; massive, t o m i l d l y f o l i a t e d where muscovite i s abundant, g r a i n s i z e banding (mm t o cm s c a l e ) i s | | S2 f o l i a t i o n and discontinuous  90-95% 08-05% 02-00%  C a l c i t e - shows e a r l y d e f o r m a t i o n t w i n n i n g and l a t e k i n k i n g ; e l o n g a t i o n c r y s t a l s 11 S2 f o l i a t i o n ; l a r g e c r y s t a l s w i t h qtz-musc i n c l u s i o n s show very jagged g r a i n boundries Muscovite - shows shredded f o r m and bent c r y s t a l s ; s t r o n g l a t t i c e - p r e f e r r e d and d i m e n s i o n a l - p r e f e r r e d o r i e n t a t i o n o u t l i n e s S2 foliation Quartz - undeformed, rounded medium s i z e d g r a i n s as i n c l u s i o n s or i n f i n e m a t r i x Assemblage  Qtz-Musc-Calcite  Name  Q t z - M u s c - C a l c i t e Marble  Page 114  Structural Seology of Part of the Crooked Lake Area, Quesnel Highlands. British Coluwbia pre  D2  post  Qtz Muse 1 Cc 2 3 Twinning Kinking Units A2a, A2b  [Alb]  {RZ8, RZ9, RZ10,RZ11}  Colour  weathered - r u s t y brown t o t a n f r e s h - t a n t o pale o l i v e  G r a i n Size  f i n e t o coarse w i t h i n t e r l a m i n a t e d c r y p t o c r y s t a l l i n e m a t e r i a l ; < 5% K - f e l d s p a r porphyro-blasts/clasts  Mineralogy  Quartz Biotite Muscovite Chlorite K-feldspar Plagioclase(An24)...  Textures  F i n e l y laminated t o f i n e l y layered; c o m p o s i t i o n a l l a y e r i n g and m y l o n i t e banding | S2 f o l i a t i o n and g e n e r a l l y d i s c o n t i n u o u s ; S2 f o l i a t i o n ranges f r o m a spaced cleavage t o a p e n e t r a t i v e f o l i a t i o n dependant on l i t h o l o g y ; an e a r l i e r f a b r i c ( s ) i s f o l d e d w i t h i n forms a s s o c i a t e d w i t h S2 f o l i a t i o n ; S2 f o l i a t i o n c r e n u l a t e d by a t l e a s t one l a t e r cleavage, f e l d s p a r e l o n g a t i o n 11 one o f these l a t e crenulations  67-89* 12-05% 08-03% 03-00% 05-02% 03-01%  Accessory Garnet Ilmenite Ctd,Apat Sphene  Quartz - common u n d u l a t o r y e x t i n c t i o n and internal grain subdivision; f i n e material along g r a i n boundries; boundries s t r a i g h t t o curved, sometimes s e r r a t e d and hazy Micas - g e n e r a l l y grow e p i t a x i a l l y ; d i m e n s i o n a l - p r e f e r r e d o r i e n t a t i o n d e f i n e s S2  Page 115  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia f o l i a t i o n and e a r l i e r f a b r i o ( s ) ; b i o t i t e shows z i r c o n i n c l u s i o n haloes K feldspar - f i n e material inclusion t r a i l s have S i * S e  [A3a] {J112, J113, J114}  Assemblages  Olig-Chl-K feldspar-Muso-Bio-Qtz Musc-Bio-Qtz  Name  Musc-Bio Q u a r t z i t e and K f e l d s p a r augen Olig-Chl-Musc-Bio-Qtz Schist  Colour  weathered - w h i t e t o r u s t y brown f r e s h - t a n t o b l u e grey  Grain Size  medium w i t h coarse b i o t i t e  Mineralogy  Quartz/Feldspar Muscovite Biotite  Textures  Coarsely l a y e r e d ( > m s c a l e ) ; c o m p o s i t i o n a l l a y e r i n g o f massive q u a r t z i t e and f e l s i c - p e l i t i c s c h i s t | | t o S2 f o l i a t i o n  porphyroblasts  90-95% 05-03% 05-02%  Micas - d i m e n t i o n a l - p r e f e r r e d o u t l i n e s S2 f o l i a t i o n Assemblages  Bio-Musc-Qtz-Feldspar  Name  Bio-Musc Q u a r t z i t e and Bio-Musc-Qtz-Feldspar Schist  pre  D2  post  Qtz Muse Bio Units A3a, A3b [A1c]  {J76}  orientation  Colour  weathered - r u s t brown f r e s h - t a n t o grey  Grain Size  medium t o coarse  Page 116  Structural Seology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia  [A3b] {J76}  Mineralogy  Quartz Muscovite Biotite Plagioclase(An26)...  65-89% 20-05% 10-05% 05-01%  Textures  F i n e l y laminated t o f i n e l y layered; c o m p o s i t i o n a l l a y e r i n g i s t i g h t l y f o l d e d and s u b - | | t o S2 f o l i a t i o n ; S2 f o l i a t i o n i s i n v o l v e d i n u p r i g h t open t o medium f o l d forms  Assemblages  Olig-Bio-Musc-Qtz Musc-Qtz  Name  B i o - M u s c - Q t z - O l i g S c h i s t and minor Muse Quartzite  Colour  weathered - p a l e y e l l o w brown f r e s h - medium b l u e grey  G r a i n Size  medium w i t h coarse garnet p o r p h y r o b l a s t s  Mineralogy  Quartz 90% Biotite 05% Muscovite 02% Garnet p o r p h y r o b l a s t s . . 0 3 %  Textures  Massive w i t h very s t r o n g l i n e a r f a b r i c ; S2 f o l i a t i o n not w e l l o u t l i n e d Micas - d i m e n s i o n a l l y r e l a t e d t o t i g h t f o l d f e a t u r e s ; p l a t e s always |I t o l i n e a r f a b r i c Garnet - i r r e g u l a r ( w e b - l i k e ) t o c o n t a i n s random i n c l u s i o n s  [Aid] {J107}  idioblastic;  Assemblage  Musc-Gn-Bio-Qtz  Name  Bio Quartzite  Colour  weathered - w h i t e t o r u s t y brown f r e s h - r u s t t a n t o grey  G r a i n Size  medium w i t h coarse m u s c o v i t e / b i o t i t e  Mineralogy  Quartz Plagioclase(An22) Musoovite Biotite  Page 117  50% Accessory 28% Garnet 15% C h l o r i t o i d 05%  Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia 02*  Ilmenite Textures  Coarsely l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f f e l s i c - p e l i t i c s c h i s t and q u a r t z i t e | | t o S2 f o l i a t i o n and g e n e r a l l y d i s c o n t i n u o u s ; S2 f o l i a t i o n i s w e l l developed t h r o u g h o u t ; S2 f o l i a t i o n i s c r e n u l a t e d by a spaced cleavage Micas - grow e p i t a x i a l l y ; d i m e n s i o n a l p r e f e r r e d o r i e n t a t i o n d e f i n e s S2 f o l i a t i o n and p o s s i b l e e a r l i e r f a b r i c (occur a t h i g h angle t o and are c u t by S2 f o l i a t i o n ) ; o c c a s s i o n a l grains cross cut f o l i a t i o n F e l s i c s - show m i l d u n d u l a t o r y extinctionss t r a i g h t t o curved g r a i n boundries  Assemblages  Ilm-Bio-Musc-Dlig-Qtz Bio-Musc-Qtz  Name  B i o - M u s c - O l i g - Q t z S c h i s t and Bio-Musc Quartzite  D2  D3  Qtz Plag Muse Bio Gn Units A i d , A l e [A2b] {J74}  Colour  weathered - t a n t o r u s t brown f r e s h - t a n t o b l u e grey  G r a i n Size  medium  Mineralogy  Calcite 85-05% Muscovite 10-20% Quartz 05-40% Plagioclase(An90)...00-30% Biotite 00-05%  Textures  F i n e t o medium l a y e r e d ; on f i n e t o medium s c a l e c o m p o s i t i o n a l l a y e r i n g o f marble and s c h i s t t o q u a r t z i t e d i s c o n t i n u o u s t o vaguely Page 118  Accessory Sphene  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British colunbia g n e i s s i o and o u t l i n e s i n t r a f o l i a l r o o t l e s s i s o c l i n a l f o l d s ; on medium t o coarse s c a l e marble occurs as i s o c l i n a l l y f o l d e d lenses w i t h i n s c h i s t / q u a r t z i t e ; S2 f o l i a t i o n shows m i l d l y u n d u l a t i n g f o r m and i s c r e n u l a t e d by a t l e a s t one l a t e r cleavages  [A4a] {J75}  Assemblages  Qtz-Felds-Musc-Cc Bio-Musc-Qtz  Name  Qtz-An-Musc-Cc Marble, Muse Q u a r t z i t e , Bio-Musc-Qtz S c h i s t  Colour  weathered - g r e e n i s h grey  and  f r e s h - l i g h t grey t o dark grey G r a i n Size  medium t o coarse  Mineralogy  Hornblende 70-18% Accessories Quartz 07-22% P y r i t e , R u t i l e Epidote 23-60% S p i n e l F i n e l y laminated t o f i n e l y layered; o o m p o s i t i o n a l l a y e r i n g of h o r n b l e n d e - r i o h and e p i d o t e - r i c h subunits i s discontinuous t o g n e i s s i o ( p o s s i b l y of metamorphic o r i g i n ) and involved i n rootless i n t r a f o l i a l isoclines; S2 f o l i a t i o n i s p e r v a s i v e throughout  Textures  Hornblende - some h i g h angle g r a i n s c u t by f o l i a t i o n may r e p r e s e n t e a r l y formed f a b r i c ; s t r o n g l y d e f i n e s S2 f o l i a t i o n and a l i n e a r f a b r i c w i t h i n f o l i a t i o n ; p o i k i l o b l a s t i c grains show i n c l u s i o n t r a i l s w i t h S i # Se Quartz - shows d e f o r m a t i o n bands and s t r o n g u n d u l a t o r y e x t i n c t i o n ; g r a i n boundries are curved but d i s t i n c t Assemblage  Qtz-Ep-Hnbd  Name  Qtz-Ep-Hnbd S c h i s t  Page 119  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluitbla pre Qtz Hnbd  D2  post  I-—j  — j  EP  |  Sphene  I  Rutile  j  j —  j j  Unit A4  [Ale] {J73, J72}  Colour  weathered - r u s t brown t o r e d brown f r e s h - r e d brown t o dark grey  G r a i n Size  medium t o coarse  Mineralogy  Quartz Muscovite Biotite Plagioclase(An36)... Garnet  Textures  F i n e l y laminated t o f i n e l y layered; c o m p o s i t i o n a l l a y e r i n g o f p e l i t i c and p e l i t i c - f e l s i c s c h i s t s discontinuous t o g n e i s s i c and i n v o l v e d i n r o o t l e s s i n t r a f o l i a l isoclines  Assemblage  Gn-Ands-Bio-Musc-Qtz  Name  Gn-Ands-Bio-Musc-Qtz S c h i s t  Page 120  05-75* 70-05* 10-10* 10-05% 00-05%  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia ANTLER FORMATION [B1a] {RZ1, RZ1}  Colour  weathered - r u s t y brown t o l i g h t green f r e s h - b l u e green t o l i g h t green  G r a i n Size  very f i n e w i t h f i n e t o medium c h l , b i o , hnbd, mgt  Mineralogy  Quartz Albite Chlorite Biotite Hornblende Magnetite Epidote Calcite  Textures  Finely laminated; compositional l a y e r i n g of c h l - q t z s c h i s t and ep-hnbd-chl meta- wacke d i s c o n t i n u o u s and | | t o S2 f o l i a t i o n ; S2 f o l i a t i o n ranges f r o m a p e n e t r a t i v e f a b r i c i n m a f i c r i c h u n i t s t o a congugate spaced c l e a v a g e / f r a c t u r e i n f e l s i c r i c h u n i t s ; S2 f o l i a t i o n i s c r e n u l a t e d by one l a t e r cleavage  40-88* 35-00* 10-03* 05-00* 05-03* 00-04* 03-01* 02-01*  F e l s i c s - show c l a s t i c or p o s s i b l y texture Micas - d i m e n s i o n a l - p r e f e r e d o u t l i n e s S2 f o l i a t i o n  cataclastic  orientation  Hornblende - g r a i n s found t o l i e a t h i g h angle t o S2 f o l i a t i o n c r o s s - c u t c h l o r i t e g r a i n s ; some show corroded o u t l i n e s Assemblages  Cc-Ep-Bio-Hnbd-Chl-Ab-Qtz Hnbd-Chl-Mgt-Qtz  Name  Bio-Hnbd-Chl-Ab-Qtz S c h i s t , Hnbd-Chl-Mgt-Qtz S c h i s t , and minor massive Q u a r t z i t e  Page 121  Structural Geology of Part of the Crooked lake Area. Quesnel Highlands. British Colunbia pre  D2  post  Units B1a, B i d [B2a] {RZ1, RZ1,  Colour  weathered - t a n t o r u s t y brown f r e s h - b l u e green t o dark green  RZ3}  Grain Size  very f i n e w i t h f i n e t o medium hnbd, b i o  Mineralogy  Quartz 03-10* Albite 40-20% Chlorite 10-05% Epidote 10-35% ornblende . . 30-00% i o t i t e (oxy-verm?). 00-20% Calcite 05-10% Magnetite 02-00%  B Textures  Finely laminated; compositional layering of e p i d o t e r i c h and hornblende r i c h u n i t s sub I| t o S2 f o l i a t i o n and shows involvement i n p o s s i b l e t i g h t i n t r a f o l i a l f o l d forms; numerous e p - f e l s i c v e i n s , l e n s o i d s , and spheroids show an arrangement |I t o c o m p o s i t i o n a l l a y e r i n g ; S2 f o l i a t i o n shows a p e n e t r a t i v e or spaced f a b r i c dependent on lithology Hornblende - g r a i n s grow across g r a i n s t h a t o u t l i n e S2 f o l i a t i o n C h l o r i t e - dimensional-preferred outlines f o l i a t i o n  orientation  B i o t i t e - some g r a i n s l i e a t h i g h angle t o and are c u t by o t h e r g r a i n s t h a t o u t l i n e / d e f i n e S2 foliation  Page 122  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia M a g n e t i t e - g r a i n s have q u a r t z pressure shadows a l i g n e d w i t h S2 f o l i a t i o n Assemblages  Mgt-Qtz-Cc-Ep-Chl-Hnbd-Ab Chl-Cc-Qtz-Bio-Ab-Ep  Name  Ep-Chl-Hnbd-Ab S c h i s t and Cc-Qtz-Bio-Ab-Ep meta-wacke  02  Qtz Ab Hnbd Bio Chl Mgt Ep-Cc veins  post  Unit B2a [B3a] {RZ3, RZ4}  Colour  weathered - t a n t o r u s t y brown t o w h i t e green f r e s h - dark green t o p i s t a c h i o green  Grain Size  very f i n e t o f i n e  Mineralogy  Quartz Epidote Chlorite Hornblende Magnetite Calcite Albite  Textures  F i n e l y laminated t o f i n e l y layered; c o m p o s i t i o n a l l a y e r i n g ranges from f a i r l y continuous t o d i s c o n t i n u o u s becoming l e n s e - l i k e and s p h e r o i d a l and i s mostly | | t o S2 f o l i a t i o n ; f o l i a t i o n i s p e n e t r a t i v e i n c h l o r i t e r i c h u n i t s , o t h e r w i s e i s best o u t l i n e d by f e l s i c - c c - e p l e n s o i d / s p h e r o i d s ; S2 f o l i a t i o n has been c r e n u l a t e d by two l a t e r cleavages  42-40% 35-30% 05-25% 05-04% 05-00% 02-01% 05-00%  Accessory Biotite  C h l o r i t e - dimensional-preferred d e f i n e s S2 f o l i a t i o n  Page 123  orientation  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Hornblende - some g r a i n s o r o s 6 S2 f o l i a t i o n c h l o r i t e s ; show zoning from c l e a r ( a c t i n o l i t i c ) i n t e r i o r s t o pleochroic ( h o r n b l e n d i c ) rims C a l c i t e - g r a i n s show h i g h degree o f t w i n n i n g Assemblages  Ab-Cc-Mgt-Hnbd-Qtz-Chl-Ep Ab-Cc-Qtz-Hnbd-Chl-Ep  Name  Ab-Hnbd-Chl-Ep-Qtz S c h i s t and Ab-Hnbd-Chl-Ep-Qtz m e t a - l i t h i c wacke  pre  02  post  Qtz Ab Act Chl Mgt Ep-Cc veins Unit B3a [B1b] {RZ4}  Colour  weathered - r u s t brown t o l i g h t green f r e s h - l i g h t green t o t a n  Grain Size  f i n e t o medium  Hineralogy  Albite Quartz Hornblende Chlorite Epidote Hagnetite  Textures  Hassive t o f i n e l y l a y e r e d ; S2 f o l i a t i o n d i s t i n c t o n l y where h o r n b l e n d e / c h l o r i t e are abundant, o t h e r w i s e i s represented by a c o n j u g a t e spaced cleavage  45% 35% 10% 05% 03% 02%  Hornblende/Chlorite - dimensional- preferred o r i e n t a t i o n d e f i n e s f o l i a t i o n ; probably not r e f l e c t i n g p r e - f o l i a t i o n compositional layering  Page 124  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia  [B4a] {RZ4}  Assemblage  Mgt-Ep-Chl-Hnbd-Qtz-Ab  Name  Hnbd-Qtz-Ab Meta-wacke and Ep-Chl-Qtz-Ab Meta-wacke  Colour  weathered - orange brown f r e s h - medium b l u i s h - g r e y t o g r e e n i s h - g r e y  B r a i n Size  very coarse w i t h f i n e s e r p e n t i n e along fractures  Mineralogy  Olivine Orthopyroxene Crysotile Calcite  Textures  40* 35* 20* 05*  Massive and h i g h l y f r a c t u r e d S e r p e n t i n e - l i e s along f r a c t u r e planes i n o l i v i n e and along cleavage planes i n orthopyroxene ( g r a i n boundries???) O l i v i n e / O r t h o p y r o x e n e - assumed t o r e p r e s e n t o r i g i n a l makeup o f rock, now i s seen as s m a l l p e i c e s o f g r a i n s f l o a t i n g on a background o f s e r p e n t i n e ; many adjacent g r a i n s are o p t i c a l l y coincident C a l c i t e - occurs w i t h s e r p e n t i n e and a l s o i n l a r g e r scaled veins  Assemblage  Cc-Serp-0px-01  Name  Serpentinized p e r i d o t i t e  01 En Serp Cc Unit B4a [Bicj {RZ5}  Colour  weathered - g r e e n i s h - g r e y t o l i g h t grey fresh - bluish-grey t o tan  G r a i n Size  f i n e t o medium Page 125  Structural geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Mineralogy  Quartz Epidote Chlorite. Hornblende Magnetite Albite  45-10% 25-30% 20-05% 05-50% 05-00% 00-05%  Textures  F i n e l y laminated t o f i n e l y layered; c o m p o s i t i o n a l l a y e r i n g o f c h l - h n b d and e p - f e l s i c u n i t s ranges f r o m f a i r l y continuous t o d i s c o n t i n u o u s becoming l e n s o i d t o s p h e r o i d ( p a r t i c u l a r i l y t h e f e l s i c u n i t s ) and i s | | S2 f o l i a t i o n ; S2 f o l i a t i o n i s best seen i n c h l / h n b d u n i t s and invoved i n u p r i g h t medium "Z" f o l d i n g (wavelengths dm t o m s c a l e ) ; f o l d s are o f t e n a s s o c i a t e d w i t h a x i a l f a u l t s t h a t s l i c e or destroy the short limb Hornblende - most g r a i n s show dimensional-preferred o r i e n t a t i o n t h a t defines t h e S2 f o l i a t i o n ; some g r a i n s l i e a t h i g h angle t o and are c r o s s - c u t by S2 f o l i a t i o n grains C hlor it e - dimensional-preferred o u t l i n e s S2 f o l i a t i o n  orientation  E p i d o t e - g r a i n s commonly f o r m l e n s o i d a l masses | | t o S2 f o l i a t i o n Assemblages  Chl-Ep-Qtz Ab-Chl-Qtz-Ep-Hnbd  Name  Chl-Ep-Qtz Meta-wacke Ab-Chl-Qtz-Ep-Hnbd Schist  pre  D2  Qtz Ab Hnbd Chl Mgt Ep-Cc veins Unit B1c [B5a] Page 126  post  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia {V5b}  Colour  weathered - t a n t o o l i v e grey f r e s h - w h i t e t o medium g r e e n i s h grey  Grain Size Mineralogy  Textures  f i n e t o medium w i t h very coarse hornblende Hornblende SO* Quartz 35* Plagioclase(AnO-IO) 05* Opaque 08* Epidote 02* F i n e t o medium l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f e p - f e l s i c and hornblende u n i t s | | t o S2 f o l i a t i o n ; S2 f o l i a t i o n i n v o l v e d i n medium t o t i g h t i n t r a f o l i a l f o l d packages Hornblende - semi-random s p l a y s ooour i n p l a n a r zones o u t l i n i n g S2 f o l i a t i o n E p i d o t e - occurs as l e n s o i d / s p h e r o i d bodies t h a t o u t l i n e f o l i a t i o n ; more c o n c e n t r a t e d toward t h e t o p F e l s i c s - commonly incuded w i t h hornblende porphyroblasts  Assemblage  Ep-Ab-Opaque-Qtz-Hnbd  Name  Ab-Qtz-Hnbd S c h i s t  pre  D2  post  Qtz Ab Hnbd Ep Cc Chl Mgt Unit B5a [B2bJ {V5a}  Colour  weathered - o l i v e grey  Page 127  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. B r i t i s h Coluwbia f r e s h - medium g r e e n i s h grey Grain Size  f i n e t o medium w i t h coarse carbonate lensoids/veins  Mineralogy  Quartz Plagioclase(AnO-10) Hornblende Carbonate Chlorite Opaque  Textures  Massive t o weakly l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f hornblende and c h l o r i t e - c a r b o n a t e u n i t s | | t o f o l i a t i o n ; extremely s c h i s t o s e toward t o p  40* 10* 20* 15* 10* 05*  Accessory Fe-oxide staining  Hornblende - occurs as random s p l a y s i n p l a n a r zones o u t l i n i n g f o l i a t i o n or as evenly d i s t r i b u t e d p o r p h y r o b l a s t i c masses g i v i n g s p o t t y appearance t o u n i t C h l o r i t e - dimensional p r e f e r r e d o r i e n t a t i o n o u t l i n e s weak f o l i a t i o n  [B1f]  Assemblages  Opaque-Chl-Ab-Cc-Hnbd-Qtz  Name  Chl-Ab-Cc-Hnbd-Qtz Meta-wacke  Colour  weathered - y e l l o w i s h green f r e s h - g r e y i s h green  Grain Size  f i n e t o medium w i t h coarse hornblende  Mineralogy  Quartz 35* Chlorite 30* Clinozoisite/Epidote...25* Plagioclase(?An35?) 05* Actinolite 05*  Textures  Medium l a y e r e d and massive; f a i r l y continuous c l z - q t z u n i t s a l t e r n a t e w i t h hnbd u n i t s ; u p s e c t i o n grades i n t o l e n s o i d / s p h e r o i d s i n a c h l o r i t i c m a t r i x ; c o m p o s i t i o n a l l a y e r i n g 11 t o foliation  Assemblages  Ands-Act-Clz-Chl-Qtz  Name  Clz-Chl-Qtz Schist  Page 128  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Colour  weathered - y e l l o w green t o w h i t e f r e s h - pale green  Grain Size  f i n e t o medium  Mineralogy  Chlorite Clinozoisite Quartz P l a g i o c l a s e (An37) Calcite  Textures  G e n e r a l l y massive w i t h Qtz-Cc-Clz v e i n i n g to foliation  35% 30% 20% 10% 05% ||  C h l o r i t e - dimensional p r e f e r r e d o r i e n t a t i o n outlines f o l i a t i o n C l i n o z o i s i t e - o f t e n seen zoned w i t h e p i d o t i c cores  b] a,b}  Assemblages  Cc-Ands-Qtz-Clz-Chl  Name  Ands-Qtz-Clz-Chl Schist  Colour  weathered - brownish-grey t o g r e e n i s h grey f r e s h - y e l l o w green t o o l i v e black  G r a i n Size  medium t o coarse  Mineralogy  Hornblende/Actinolite..60% P l a g i o c l a s e (An36) 25% Epidote 15%  Textures  Medium t o c o a r s e l y l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f massive hornblende and amph-ands-ep u n i t s | | t o f o l i a t i o n ; some t i g h t i n t r a f o l i a l f o l d i n g of compositional layering and f o l i a t i o n Amphiboles - dimensional p r e f e r r e d o r i e n t a t i o n of smaller grains o u t l i n e f o l i a t i o n ; larger g r a i n s l i e a t h i g h e r angles t o f o l i a t i o n and are o f t e n t r u n c a t e d by s m a l l e r ; p a r g a s i t e occurs i n massive u n i t s  Assemblages  Ep-Ands-Hnbd  Name  Ep-Ands-Hnbd S c h i s t  Page 129  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia [B2c] {V1}  Colour  weathered - g r e e n i s h grey " f r e s h - g r e y i s h green  G r a i n Size  coarse w i t h very coarse amphiboles  Mineralogy  Clinozoisite 50% A c t i n o l i t e / T r e m o l i t e . . . 40* Plagioclase(An38) 10*  Textures  Massive t o weakly l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f c l z and amph-plag u n i t s 11 t o foliation Amphibole - weak dimensional p r e f e r r e d orientation outlines f o l i a t i o n  [B5c] {J108}  Assemblages  Ands-Act-Clz  Name  Ands-Act-Clz Schist  Colour  weathered - r u s t y brown f r e s h - dark green t o black  G r a i n Size  f i n e t o medium  Mineralogy  Hornblende/Actinolite.. 50* Epidote 15* Felsic 35* Medium t o coarse l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f e p - f e l s i c and hnbd u n i t s | | t o foliation  Textures  Amphiboles - dimensional p r e f e r r e d outlines f o l i a t i o n  [B5d] {J107}  orientation  Assemblages  Ep-Felsic-Hnbd  Name  E p - F e l s i c Hnbd S c h i s t  Colour  weathered - r u s t brown t o w h i t e green f r e s h - grey green t o dark green  G r a i n Size  very f i n e t o f i n e w i t h coarse a c t i n o l i t e  Mineralogy  Actinolite Clinozoisite  Page 130  70* 20*  Accessory Fine opaque  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Felsics. Textures  10%  Medium t o c o a r s e l y l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f opaque ' s t r e a k e d ' and c l e a r u n i t s I| t o f o l i a t i o n A c t i n o l i t e - dimensional p r e f e r r e d o r i e n t a t i o n o f s m a l l e r g r a i n s o u t l i n e S2 f o l i a t i o n ; l a r g e r g r a i n s o r i e n t e d a t v a r i o u s angles t o and t r u n c a t e d by f o l i a t i o n  I5e] 1101, 04}  Assemblages  Felsic-Clz-Act  Name  Felsic-Clz-Act Schist  Colour  weathered - grey green t o r u s t brown f r e s h - grey green  Grain S i z e  f i n e t o medium w i t h coarse t o very coarse hornblende  Mineralogy  Hornblende Quartz Albite Epidote Biotite Chlorite Calcite Ilmenite  Textures  F i n e l y l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f hnbd r i c h and e p - f e l d s r i c h u n i t s | | t o S2 f o l i a t i o n ; S2 f o l i a t i o n most d i s t i n c t i n hnbd r i c h u n i t s , though a l s o o u t l i n e d by o r i e n t a t i o n of e p - f e l d s l e n s o i d / s p h e r o i d s ; p o s s i b l e S2 f o l i a t i o n involvement i n medium t o tight folding  20-50% 56-20% 05-05% 03-05% 10-00% 05-17% 00-03% 01-00%  Hornblende - l o c a l l y present w i t h s m a l l e r amounts o f p a r g a s i t e ; shows a semi-random arrangement mostly w i t h i n p l a n a r zones C h l o r i t e / B i o t i t e - dimensional p r e f e r r e d o r i e n t a t i o n o u t l i n e s f o l i a t i o n ; forms along f r a c t u r e s i n hornblende F e l s i c s - u n d u l a t o r y e x t i n c t i o n and d e f o r m a t i o n banding i s common  Page 131  structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Colunbia Assemblages  Cc-Qtz-Ep-Chl-Ab-Hnbd Ilm-Ep-Parg-Ab-Chl-Bio-Hnbd-Qtz  Name  Ep-Chl-Bio-Ab-Qtz-Hnbd S c h i s t  Page 132  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia EUREKA QUARTZITE [C1a] {J86}  Colour  weathered - l i g h t brown t o grey f r e s h - l i g h t grey t o blue grey  G r a i n Size  f i n e t o medium  Mineralogy  Quartz Biotite Muscovite Chlorite  Textures  F i n e t o medium l a y e r i n g ; c o m p o s i t i o n a l l a y e r i n g o f g r a p h i t i c and quartzose units m o s t l y | | t o S2 f o l i a t i o n ; t i g h t f o l d s o f c o m p o s i t i o n a l l a y e r i n g w i t h S2 f o l i a t i o n as a x i a l plane are i n v o l v e d i n c o a x i a l u p r i g h t medium f o l d s whose a x i a l plane i s represented by a spaced cleavage  85-90* 10-05* 05-03* 00-02*  Accessory Garnet Magnetite  Micas - dimensional p r e f e r r e d o r i e n t a t i o n d e f i n e s S2 f o l i a t i o n ; some g r a i n s a t h i g h angle t o f o l i a t i o n are k i n k e d ; a s s o c i a t e d w i t h opaques; some growth along S3 cleavage planes Quartz - elongate | | t o S2 f o l i a t i o n ; g r a i n boundries are s e r r a t e d and hazy; u n d u l a t o r y e x t i n c t i o n and d e f o r m a t i o n bands are common; coarser g r a i n s c o u l d belong t o v e i n i n g I| S2  [C1b] {J104}  Assemblages  Bio-Qtz Musc-Bio-Qtz  Name  Musc-Bio Q u a r t z i t e  Colour  weathered - l i g h t brown and dark grey f r e s h - grey t o medium blue grey  G r a i n Size  f i n e t o medium  Mineralogy  Quartz Biotite Muscovite Chlorite Hornblende  Textures  F i n e t o medium l a y e r i n g ; c o m p o s i t i o n a l l a y e r i n g o f g r a p h i t i c and quartzose units m o s t l y | | t o S2 f o l i a t i o n ; t i g h t f o l d s o f Page 133  85-90% 08-05* 00-03* 00-02* 05-00*  Accessory Garnet Magnetite Epidote Graphite  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia c o m p o s i t i o n a l l a y e r i n g w i t h S2 f o l i a t i o n as a x i a l plane are i n v o l v e d i n c o a x i a l u p r i g h t medium f o l d s whose a x i a l plane i s represented by a spaced cleavage Micas - dimensional p r e f e r r e d o r i e n t a t i o n d e f i n e s S2 f o l i a t i o n ; some g r a i n s a t h i g h angle t o f o l i a t i o n are kinked Quartz - e l o n g a t e j | t o S2 f o l i a t i o n ; u n d u l a t o r y e x t i n c t i o n and d e f o r m a t i o n bands are common; g r a i n boundries are s e r r a t e d and hazy Garnet - a r e l a t i o n s h i p w i t h mgt-hnbd-bio-ep i s suggested Assemblages  Ep-Hnbd-Bio-Qtz Gn-Mgt-Chl-Musc-Bio-Qtz  Name  B i o Q u a r t z i t e w i t h l o c a l Ep-Hnbd-Bio Q u a r t z i t e or Gn-Mgt-Chl-Musc-Bio Q u a r t z i t e  Qtz Bio Muse Chl (Hnbd) (Gn) (Mgt) Unit C1b  Page 134  Structural Geology of Part of the Crooked Lake Area, quesnel Highlands. British Columbia CROOKED LAKE PHYLLITE [D1a] {J45}  Colour  weathered - grey brown t o t a n and r u s t y brown t o p a l e green f r e s h - grey t o grey black and r u s t y orange  G r a i n Size  two i n t e r l a y e r e d v a r i e t i e s : - very f i n e t o f i n e p h y l l i t e - f i n e t o medium s c h i s t w i t h very coarse ankerite  Mineralogy  Quartz Muscovite Ankerite Chlorite Graphite  Textures  Medium l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f black t o grey p h y l l i t e and a n k e r i t e s c h i s t |I t o S2 f o l i a t i o n ; f o l i a t i o n i s c r e n u l a t e d by two l a t e r cleavages  Assemblages  Chl-Graph-Qtz-Musc Musc-Qtz-Chl-Ank  Name  Graph-Qtz-Musc P h y l l i t e i n t e r l a y e r e d w i t h z Qtz-Chl-Ank S c h i s t  pre  D2  15-30% 05-35% 50-00% 30-05% 00-30%  post  Qtz Muse Chl Ank Unit D1a, D1b, D1c [02a] {J52}  Colour  weathered - r u s t y c o a l grey t o l i g h t grey and brown f r e s h - grey w h i t e t o medium grey and red brown  G r a i n Size  very f i n e t o f i n e  Mineralogy  Quartz  80-25% Page 135  structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British colunbia Muscovite Chlorite Graphite Calcite (  08-40% 10-05% 02-25% 00-05%  Textures  F i n e t o medium l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f p h y l l i t e and sandstone a t h i g h angle t o S2 f o l i a t i o n / c l e a v a g e ; S2 f o l i a t i o n associated w i t h open f o l d i n g o f c o m p o s i t i o n a l l a y e r i n g ; f o l i a t i o n i s open f o l d e d about a steep a x i s toward t h e n o r t h  Assemblages  Cc-Chl-Graph-Qtz-Musc Musc-Chl-Qtz  Name  Chl-Graph-Qtz-Musc P h y l l i t e w i t h very minor Musc-Chl Q u a r t z i t e  Qtz Muse Chl Mm Tour  pre |-—| j j j  D2  post • j  Unit D2 [D3a] <J41>  Colour  weathered - dark brown t o y e l l o w r u s t brown f r e s h - l i g h t grey t o y e l l o w grey  Grain Size  f i n e t o medium  Mineralogy  K-Feldspar Quartz Pyrite  Textures  Massive; a s o l i t a r y one t o two meter u n i t s e t i n p h y l l i t e matrix  80% 10% 10%  K-Feldspar - c o n t a i n s abundant q u a r t z i n c l u s i o n s t h a t resembles myrmekite; p o s s i b l e s e r i c i t i z a t i o n ; c l a s t i c g r a i n boundries preserved w i t h q u a r t z cement  Page 136  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia  [D2b] {J40}  [Dlb] {J57}  Assemblages  Py-Qtz-Kspar  Name  M y r m e k i t i c - K s p a r Meta-arkose  Colour  weathered - r u s t y c o a l grey and t a n f r e s h - grey b l a c k and w h i t e grey  Grain Size  very f i n e t o medium  Mineralogy  Quartz Muscovite Chlorite Graphite  Textures  Medium l a y e r e d ; * sandy* u n i t s c o n s t i t u t e 10-50* o f l i t h o l o g y ; c o m p o s i t i o n a l l a y e r i n g a t h i g h angle t o S2 f o l i a t i o n / c l e a v a g e ; f o l i a t i o n i s a x i a l p l a n a r t o open/medium f o l d s o f compositional layering; f o l i a t i o n i s open/medium f o l d e d  Assemblages  Chl-Musc-Qtz-(Graph)  Name  Chl-Musc-Qtz-Graph P h y l l i t e i n t e r l a y e r e d w i t h Chl-Musc Q u a r t z i t e  Colour  weathered - grey-brown t o t a n f r e s h - grey t o g r e y - b l a c k , w h i t e , and r u s t y orange  G r a i n Size  very f i n e w i t h coarse a n k e r i t e  Mineralogy  Ankerite Chlorite Quartz Muscovite  Textures  F i n e l y l a y e r e d ; vague c o m p o s i t i o n a l l a y e r i n g o f a n k e r i t e and m u s c - c h l - q t z u n i t s a t h i g h angle t o S2 f o l i a t i o n  70-30* 20-30* 10-05* 00-35*  85-10* 00-45* 02-20* 10-05*  A n k e r i t e - alignment o f g r a i n s i n d i r e c t i o n o f S2 f o l i a t i o n suggests development o f new compositional f a b r i c Muscovite - dimensional p r e f e r r e d o r i e n t a t i o n o u t l i n e s weak f o l i a t i o n  Page 137  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia  [D2c] {J9}  Assemblages  Qtz-Musc-Ank Musc-Ank-Qtz-Chl  Name  Otz-Musc-Ank S c h i s t and Musc-Ank-Qtz-Chl S c h i s t i n t e r l a y e r e d w i t h p h y l l i t e and quartzite  Colour  weathered - r u s t y c o a l grey t o l i g h t grey f r e s h - grey w h i t e and medium grey  Grain S i z e  very f i n e t o f i n e w i t h coarse i l m e n i t e  Mineralogy  Quartz Muscovite Chlorite Fine opaque Ilmenite  Textures  F i n e l y l a y e r e d and medium l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f qtz-musc and ' g r a p h i t i c ' u n i t s on t h e s m a l l e r s c a l e and q u a r t z i t e / s a n d s t o n e s and p h y l l i t e / s i l t s t o n e s on t h e l a r g e r s c a l e predominately 11 t o S2 f o l i a t i o n where f o l d i n g o f c o m p o s i t i o n a l l a y e r i n g i s t i g h t ; l e s s common are occurrences o f open t o medium f o l d i n g o f c o m p o s i t i o n a l l a y e r i n g where t h e S2 f o l i a t i o n / cleavage i s a x i a l p l a n a r ; one l a t e r cleavage l i e s s u b - | | t o S2 f o l i a t i o n ; another cleavage l i e s a t a l a r g e angle t o S2 f o l i a t i o n and i s a s s o c i a t e d w i t h open t o medium buckle f o l d i n g of S2 f o l i a t i o n , and c o m p o s i t i o n a l l a y e r i n g e s p e c i a l l y where t i g h t e s t e a r l y f o l d s occur  30-40% 20-50% 01-05% 48-04% 01-01%  Accessory Tourmaline  Muscovite - dimensional p r e f e r r e d o r i e n t a t i o n o u t l i n e s S2 f o l i a t i o n ; p o l y g o n a l a r c s suggest t r a n s p o s i t i o n o f an e a r l i e r f a b r i c C h l o r i t e - forms a u g e n - l i k e masses; basal cleavage i s g e n e r a l l y o r i e n t e d a t h i g h angle t o S2 f o l i a t i o n I l m e n i t e - h i g h angle g r a i n s are bent and show pressure shadows | | t o S2 f o l i a t i o n Assemblages  Ilm-Graph-Chl-Qtz-Musc  Page 138  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Ilm-Chl-Musc-Qtz-Graph  [D3b] {J78}  Name  G r a p h i t i c Musc-Qtz P h y l l i t e , Chl-Qtz-Musc M e t a - s i l t s t o n e , and minor Musc-Chl Q u a r t z i t e  Colour  weathered - l i g h t green t o t a n green f r e s h - green grey  G r a i n Size  fine  Mineralogy  Quartz Muscovite Chlorite  Textures  Finely layered; compositional layering of p h y l l i t e and p h y l l i t i c s i l t s t o n e | | and a t h i g h angle t o f o l i a t i o n ; f o l i a t i o n a s s o c i a t e d w i t h recumbant open/medium f o l d s of compositional layering; f o l i a t i o n i s involved i n u p r i g h t open/medium f o l d s e s p e c i a l l y where c o m p o s i t i o n a l l a y e r i n g i s transposed; u p r i g h t k i n k forms o f f o l i a t i o n a l s o occur w i t h t r e n d s a t h i g h angle t o t h e e a r l i e r f o l d forms  Assemblages  Chl-Musc-Qtz  Name  Musc-Qtz P h y l l i t i c pre  90% 08% 02%  D2  siltstone  post  Qtz Muse Chl (Ab) llm (K-spar)  (Py) U n i t D3  [D2dJ {J69}  Colour  weathered - r u s t y c o a l grey t o l i g h t grey f r e s h - grey w h i t e and medium grey  G r a i n Size  very f i n e t o f i n e w i t h coarse muscovite Page 139  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Mineralogy  Quartz Muscovite Chlorite F i n e opaque  Textures  F i n e t o medium l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f p h y l l i t i c s i l t s t o n e and p h y l l i t e | | t o S2 f o l i a t i o n ; an extremely p e r v a s i v e h o r i z o n t a l f o l i a t i o n i s c r e n u l a t e d by S2 f o l i a t i o n ; abundant q u a r t z v e i n i n g occurs  Assemblages  Chl-Musc-Qtz-Graph Graph-Chl-Qtz-Musc  Name  Musc-Qtz-Graph P h y l l i t e i n t e r l a y e r e d w i t h Chl-Qtz-Musc M e t a - s i l t s t o n e  30-40% 20-50% 02-06% 48-04%  [Die]  {J77}  Colour  G r a i n Size  Mineralogy  weathered - t a n t o grey and r u s t y brown t o p a l e green f r e s h - l i g h t grey t o dark grey and grey green two i n t e r l a y e r e d species: - very f i n e t o f i n e p h y l l i t e - f i n e t o medium s c h i s t w i t h coarse a n k e r i t e Quartz Muscovite Ankerite Chlorite Graphite  15-30% 05-35% 50-00% 30-05% 00-30%  Textures  Medium l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f p h y l l i t e , s c h i s t , and q u a r t z i t e i s | | t o and a t h i g h angle t o f o l i a t i o n ; S2 f o l i a t i o n c r e n u l a t e s a very f l a t cleavage; S2 f o l i a t i o n i s openly f o l d e d  Assemblages  Musc-Qtz-Chl-Ank Chl-Graph-Qtz-Musc  Name  Graph-Qtz-Musc P h y l l i t e i n t e r l a y e r e d w i t h Qtz-Chl-Ank S c h i s t and minor Q u a r t z i t e  [D4a] {J67}  Colour  weathered - l i g h t grey t o c o a l grey  Page 140  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia f r e s h - medium grey Grain Size  very f i n e t o f i n e w i t h coarse i l m e n i t e and very coarse p l a g i o c l a s e and c h l o r i t o i d  Mineralogy  Quartz Muscovite Chlorite Plagioclase Chloritoid Graphite Ilmenite  Textures  F i n e l y l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g of p h y l l i t e and p o r p h y r o b l a s t i c u n i t s | | t o S2 f o l i a t i o n ; f o l i a t i o n i s l o c a l l y d e f l e c t e d by porphyroblasts  55-30* 10-40* 10-05* 15-10* 05-05* 00-05* 05-05*  Accessory Tourmaline  Micas - dimensional p r e f e r r e d o r i e n t a t i o n outlines f o l i a t i o n Andesine - most abundant p o r p h y r o b l a s t ; as s i n g l e c r y s t a l s and aggregates; p o i k i l o b l a s t i c , c o n t a i n i n g i n c l u s i o n s of c h l o r i t e , q u a r t z , and t o u r m a l i n e C h l o r i t o i d - p o i k i l o b l a s t i c , c o n t a i n i n g mostly q u a r t z and i l m e n i t e ; S i I| Se; r e l a t e d t o masses o f q u a r t z - m u s c o v i t e - c h l o r i t e ; separated f r o m andesine by c h l o r i t e - F e oxide r i m ; basal planes are c o n s i s t a n t l y o r i e n t e d a t 30 degree angle t o S2 f o l i a t i o n I l m e n i t e - m o s t l y a l i g n e d 11 t o S2 f o l i a t i o n ; where a t h i g h angle show w e l l developed pressure shadows o f q u a r t z Assemblages  Ctd-Ilm-Chl-Musc-Ands-Qtz Chl-Ctd-Ilm-Graph-Ands-Qtz-Musc  Name  Ilm-Ctd-Graph-Chl-Musc-Ands-Qtz  Page 141  Schist  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia D2  D3  Qtz Muse Chl Ctd Olig Gn (Staur) Unit D4a, D4b, D4c [D2e] {J66}  [D3c] {J166}  Colour  weathered - r u s t y c o a l grey t o l i g h t grey f r e s h - grey w h i t e and medium grey  G r a i n Size  very f i n e t o f i n e w i t h coarse muscovite  Mineralogy  Quartz Muscovite Chlorite Graphite Calcite  Textures  Finely layered; compositional l a y e r i n g of limy p h y l l i t i c s i l t s t o n e and p h y l l i t e 11 t o S2 f o l i a t i o n ; abundant q u a r t z and c a l c i t e v e i n i n g occurs  Assemblages  Chl-Musc-Qtz-Graph Graph-Chl-Cc-Qtz-Musc  Name  Musc-Qtz-Graph P h y l l i t e i n t e r l a y e r e d w i t h Chl-Cc-Qtz-Musc M e t a - s i l t s t o n e  Colour  weathered - brown grey t o t a n f r e s h - l i g h t grey t o green grey  G r a i n Size  very f i n e t o f i n e  Mineralogy  Quartz Calcite Muscovite Chlorite Plagioclase(AnO) Epidote F i n e opaque Page 142  30-35% 20-45% 02-06% 48-04% 00-10%  10-25-45% 05-35-00% 00-10-15% 20-10-00% 50-15-00% 10-00-15% 05-02-00%  Structural Geology of Part of the Crooked Lake Area, quesnel Highlands. British Coluwbia Graphite Textures  00-03-25%  Complexly l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f l i m y u n i t s , p h y l l i t e , sandstone | | t o S2 f o l i a t i o n ; f o l i a t i o n i s kinked Micas - dimensional p r e f e r r e d o r i e n t a t i o n o u t l i n e s S2 f o l i a t i o n  [D2f] {J169>  [D2g] {J115}  Assemblages  Musc-Ab-Qtz-Cc Ep-Ab-Qtz Chl-Musc-Qtz-Graph  Name  I n t e r l a y e r e d Musc-Py-Ab-Qtz Marble w i t h Ep-Ab-Qtz M e t a - s i l t s t o n e  Colour  weathered - r u s t y grey t o l i g h t grey - f r e s h - grey w h i t e and medium grey  Grain Size  very f i n e t o f i n e  Mineralogy  Quartz Muscovite Chlorite Graphite Calcite  Textures  Finely layered; compositional l a y e r i n g | | t o S2 f o l i a t i o n ; abundant q u a r t z v e i n i n g occurs  Assemblages  Chl-Musc-Qtz-Graph Graph-Qtz-Musc  Name  Musc-Qtz-Graph P h y l l i t e i n t e r l a y e r e d w i t h Chl-Cc-Qtz-Musc M e t a - s i l t s t o n e  Colour  weathered - r u s t y grey t o t a n  30-35% 20-45% 02-06% 48-04% 00-10%  f r e s h - grey w h i t e and medium grey Grain Size  very f i n e t o f i n e  Mineralogy  Quartz 30-35% Muscovite 20-45% Chlorite 02-06% Graphite 48-04% Calcite 00-10% F i n e l y l a y e r e d p h y l l i t e and minor p h y l l i t i c s i l t s t o n e ; c o m p o s i t i o n a l l a y e r i n g o f | | t o S2  Textures  Page 143  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British colunbia f o l i a t i o n w i t h som t i g h t f o l d s d e v e l o p i n g ; abundant q u a r t z v e i n i n g  [D2hJ {J84>  [D4b] {J85>  Assemblages  Chl-Musc-Qtz-Graph Graph-Chl-Qtz-Musc  Name  Musc-Qtz-Graph P h y l l i t e i n t e r l a y e r e d w i t h Chl-Qtz-Musc M e t a - s i l t s t o n e  Colour  weathered - r u s t y c o a l grey t o dark grey f r e s h - grey w h i t e and medium grey  Grain Size  v e r y f i n e t o f i n e w i t h coarse muscovite  Mineralogy  Quartz Muscovite Biotite Graphite Calcite  Textures  F i n e l y l a y e r e d w i t h abundant q u a r t z v e i n i n g and boudinage; c o m p o s i t i o n a l l a y e r i n g | | t o S2 f o l i a t i o n ; some b i o t i t e p o r p h y r o b l a s t s  Assemblages  Bio-Musc-Qtz-Graph Graph-Bio-Qtz-Musc  Name  Musc-Qtz-Graph P h y l l i t e  Colour  weathered - l i g h t grey t o c o a l grey f r e s h - medium grey  G r a i n Size  very f i n e t o f i n e w i t h coarse i l m e n i t e and very coarse p l a g i o c l a s e and c h l o r i t o i d  Mineralogy  Quartz Muscovite Chlorite Plagioclase Chloritoid Graphite Ilmenite  Textures  Finely layered; compositional l a y e r i n g of p h y l l i t e and p o r p h y r o b l a s t i c u n i t s | | t o S2 f o l i a t i o n ; f o l i a t i o n i s l o c a l l y d e f l e c t e d by  Page 144  30-35% 20-45% 02-06% 48-04% 00-10%  55-30% 10-40% 10-05% 15-10% 05-05% 00-05% 05-05%  Accessory Tourmaline  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia p o r p h y r o b l a s t s ; l o c a l l y c r e n u l a t i o n s are w e l l developed away f r o m p o r p h y r o b l a s t s Micas - dimensional p r e f e r r e d o r i e n t a t i o n outlines f o l i a t i o n ; Andesine - most abundant p o r p h y r o b l a s t ; as s i n g l e c r y s t a l s and aggregates; p o i k i l o b l a s t i c , containing inclusions of c h l o r i t e , q u a r t z , and t o u r m a l i n e ; shows i n t e r n a l l y r o t a t e d S i | | S near g r a i n boundries e  C h l o r i t o i d - p o i k i l o b l a s t i c , c o n t a i n i n g mostly q u a r t z and i l m e n i t e ; S i | | Se; r e l a t e d t o masses o f q u a r t z - m u s c o v i t e - c h l o r i t e ; never i n c o n t a c t w i t h andesine; basal planes are c o n s i s t a n t l y o r i e n t e d a t low t o moderate degree angle t o S2 f o l i a t i o n I l m e n i t e - m o s t l y a l i g n e d | | t o S2 f o l i a t i o n ; where a t h i g h angle show w e l l developed pressure shadows o f q u a r t z  [D2i] {J154}  Assemblages  Ctd-Ilm-Chl-Musc-Ands-Qtz Chl-Ctd-Ilm-Graph-Ands-Qtz-Husc  Name  Ilm-Ctd-Graph-Chl-Musc-Ands-Qtz  Colour  weathered - brown grey t o green grey f r e s h - l i g h t t o medium b l u e grey  G r a i n Size  very f i n e t o f i n e w i t h medium a c t i n o l i t e  Mineralogy  Felsic 25-62% Biotite 05-03% Epidote 05-15% Actinolite 60-20% R e l i c t Hornblende...03-00% F i n e opaque 02-00%  Textures  Finely layered; compositional layering of f e l s i c and a m p h i b o l i t i c u n i t s 11 t o S2 f o l i a t i o n ; f o l i a t i o n i s openly f o l d e d  Phyllite  A c t i n o l i t e - dimensional p r e f e r r e d o r i e n t a t i o n o u t l i n e s S2 f o l i a t i o n  Page 145  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Colunbia Hornblende - c r y s t a l s g e n e r a l l y have dark cores ( o r i g i n a l ) and l i g h t r i m s ( a c t i n o l i t e ) ; b i o t i t e i s a s s o c i a t e d w i t h these c r y s t a l s  [D3d] {J152}  Assemblages  Hnbd-Ep-Bio-Felsic-Act Bio-Ep-Act-Felsic  Name  Ep-Bio-Felsic-Act P h y l l i t e interlayered with Ep-Act-Felsic Meta-siltstone  Colour  weathered - brown grey and p a l e green f r e s h - medium grey and g r e y i s h green  Grain Size  very f i n e t o f i n e w i t h medium p y r i t e and/or ankerite  Mineralogy  Quartz Plagioclase(AnO) Calcite Epidote Pyrite Ankerite Muscovite Chlorite  Textures  Massive t o s l i g h t l y l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f c a l c i t e and r u s t y opaque b e a r i n g u n i t s | | t o S2 f o l i a t i o n ; f o l i a t i o n i s kinked  15-45* 10-35* 30-05* 20-08* 10-00* 00-05* 05-02* 10-00*  Micas - dimensional p r e f e r r e d o r i e n t a t i o n o u t l i n e s S2 f o l i a t i o n C a l c i t e - shows e a r l y t w i n n i n g and l a t e k i n k i n g ; mosts t w i n s are o r i e n t e d c l o s e t o 30 degrees f r o m S2 f o l i a t i o n ; k i n k i n g predominates where t w i n s are o r i e n t e d | | t o S2 foliation  [D2J] {J118}  Assemblages  Musc-Py-Ab-Qtz-Cc Musc-Cc-Ank-Ep-Ab-Qtz  Name  Musc-Py-Ab-Qtz Marble i n t e r l a y e r e d w i t h Ep-Ab-Qtz M e t a - s i l t s t o n e  Colour  weathered - r u s t y c o a l grey t o l i g h t grey f r e s h - grey w h i t e and medium grey  G r a i n Size  very f i n e t o f i n e w i t h coarse muscovite  Page 146  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British CoHmbia  [D4c] {J120}  Mineralogy  Quartz Muscovite Chlorite Graphite  30-35% 20-55% 02-06% 48-04%  Textures  Finely layered; compositional layering of limy p h y l l i t i c s i l t s t o n e and p h y l l i t e | | t o S2 f o l i a t i o n ; f o l i a t i o n i s kinked  Assemblages  Chl-Musc-Qtz-Graph Graph-Chl-Qtz-Musc  Name  Musc-Qtz-Graph P h y l l i t e i n t e r l a y e r e d w i t h C h l Qtz-Musc M e t a - s i l t s t o n e  Colour  weathered - l i g h t grey t o c o a l grey f r e s h - medium grey  G r a i n Size  f i n e t o medium w i t h very coarse c h l o r i t o i d and garnet  Mineralogy  Chlorite Muscovite Quartz Chloritoid Ilmenite Garnet  Textures  Finely layered; compositional l a y e r i n g of micaceous and quartzose u n i t s | | S2 f o l i a t i o n ; a second c o m p o s i t i o n a l l a y e r i n g i s seen d e v e l o p i n g a t h i g h angle t o S2 f o l i a t i o n r e l a t e d t o a spaced cleavage t h a t c r e n u l a t e s S2 f o l i a t i o n  20-10% 20-45% 45-30% 03-03% 01-01% 01-01%  Accessory Tourmaline Graphite  Micas - dimensional p r e f e r r e d o r i e n t a t i o n o u t l i n e s S2 f o l i a t i o n and t o a l e s s e r degree l a t e r spaced cleavage C h l o r i t o i d - low t o moderate angle t o foliation Garnet - s e r r a t e d edges; r o t a t i o n a l i n c l u s i o n t r a i l s w i t h S± \\ S c l o s e t o g r a i n boundries e  I l m e n i t e - mostly | | t o f o l i a t i o n ; where a t h i g h angle shows w e l l developed q u a r t z pressure shadows  Page 147  Structural Geology of Part of the Crooked Lake Urea. Quesnel Highlands. British Colunbia Assemblages  Gn-Ilm-Ctd-Muso-Chl-Qtz  Name  Gn-Ilm-Ctd-Musc-Chl-Qtz P h y l l i t e i n t e r l a y e r e d w i t h p h y l l i t e and p h y l l i t i c s i l t s t o n e  Page 148  structural eeologv of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia  TAKLA GROUP  [Eia]  {J59}  Colour  weathered - r u s t y y e l l o w green t o dark green f r e s h - p i s t a c h i o green and dark green  Grain Size  very f i n e t o f i n e w i t h extremely coarse aggregates o f medium t o coarse hnbd, hnbd-ep, h n b d - e p - p l a g - ( q t z ) , and e p - p l a g - ( q t z )  Mineralogy  Plagioclase(AnO) Epidote Calcite Muscovite Chlorite Quartz Hornblende  Textures  Massive t o very c o a r s e l y l a y e r e d ; c o n t a i n s c l a s t s / f r a g m e n t s w i t h or w i t h o u t pressure shadows, s p h e r u l i t e s , and abundant c o n t o r t e d cross c u t t i n g veins  50-45% 07-03% 03-05% 25-35% 05-00% 05-10% 05-02%  Micas - dimensional p r e f e r r e d o r i e n t a t i o n o u t l i n e s f o l i a t i o n ; h i g h angle v a r i e t i e s are i n c l u d e d w i t h f i n e opaque and grow on or around hornblende E p i d o t e - forms v e i n s t h a t c u t across f o l i a t i o n a t low t o h i g h angles; broken, d i s c o n t i u o u s , and h i g h l y c o n t o r t e d Hornblende aggregates  [E2a] {J65, J1, J2}  f o r m pressure shadows on e p - p l a g  Assemblages  Cc-Qtz-Chl-Hnbd-Ep-Musc-Ab Hnbd-Ep-Cc-Qtz-Musc-Ab  Name  Qtz-Ep-Musc-Ab Meta-Breccia w i t h c l a s t s o f Hnbd, Hnbd-Ep, Hnbd-Ep-Ab-(Qtz), and Ep-Ab-(Qtz)  Colour  weathered - green o l i v e t o o l i v e black f r e s h - grey green t o green black and w h i t e green  Page 149  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Grain Size  c r y p t o c r y s t a l l i n e t o f i n e w i t h coarse p o r p h y r o c l a s t s and e l l i p s o i d a l o b j e c t s  Mineralogy  Quartz Plagioclase(AnO) Actinolite Calcite Epidote Chlorite  Textures  F i n e l y l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g of c c - a b - q t z and a c t - a b - q t z u n i t s i s d i s c o n t i n u o u s and i s o c l i n a l l y f o l d e d | | t o S2 f o l i a t i o n ; an e a r l i e r f a b r i c i s p o s s i b l y f o l d e d as w e l l ; f o l i a t i o n i s i n v o l v e d i n open f o l d s a s s o c i a t e d w i t h a spaced clevage  15-15% 23-50% 45-02% 05-30% 05-00% 07-03%  Accessory Sphene  Quartz - shows u n d u l a t o r y e x t i n c t i o n , d e f o r m a t i o n banding, and r i b b o n g r a i n s ; g e n e r a l l y c-axes o f g r a i n s l i e c l o s e t o plane of f o l i a t i o n A c t i n o l i t e - dimensional p r e f e r r e d o r i e n t a t i o n o u t l i n e s S2 f o l i a t i o n and p o s s i b l y an e a r l i e r one Assemblages  Cc-Ep-Chl-Qtz-Ab-Act Act-Chl-Qtz-Cc-Ab  Name  Qtz-Cc-Ab-Act M y l o n i t e w i t h Cc-Ab-Qtz and Chl-Ep v e i n i n g  Qtz Ab Cc Muse Act Chl  D2  D3  Ep Mylonite Unit E2a [E3a] {J44}  Colour  weathered - brown grey t o r u s t y grey green Page 150  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia f r e s h - b l u e grey t o grey green Grain Size  very f i n e t o f i n e  Mineralogy  Quartz Plagioclase(AnO) Opaques Chlorite  Textures  Medium l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f r u s t y l o o k i n g and sandy l o o k i n g u n i t s | | t o S2 foliation  20-57% 69-40% 01-01% 10-02%  Accessories Apatite Actinolite Calcite  C h i / A c t - dimensional p r e f e r r e d o r i e n t a t i o n outlines f o l i a t i o n C a l c i t e - seems t o f o r m a cement f o r grains  [E2b] {J168}  Assemblages  Chl-Qtz-Ab Chl-Ab-Qtz  Name  I n t e r l a y e r e d Qtz-Ab and Ab-Qtz M e t a - s i l t s t o n e s  Colour  weathered - pale green t o r u s t y green grey f r e s h - green grey medium w i t h some coarse angular fragments  Grain Size  [E1b] {J144}  felsic  Mineralogy  Plagioclase(AnO) Quartz Chlorite Opaques  Textures  Coarse l a y e r i n g o f sandy u n i t s w i t h some l o c a l breccia units. L a y e r i n g | | S2 f o l i a t i o n .  Assemblages  Chl-Qtz-Ab  Name  C h l - q t z - a b meta-sandstone  Colour  weathered - r u s t y pale green f r e s h - grey t o grey green and dark green  G r a i n Size  extremely coarse c l a s t s w i t h minor f i n e grained matrix  Mineralogy  Plagioclase(AnO) Quartz Hornblende Page 151  60-45% 20-35% 18-15% 02-05%  45-40% 02-10% 05-20%  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Chlorite Epidote  35-05% 13-25%  Textures  Massive; c l a s t s are rounded t o sub- rounded w i t h l e s s t h a n 20% m a t r i x ; f o l i a t i o n cannot be c l e a r l y discerned w i t h i n t h i s u n i t ; contact w i t h lower u n i t s | | t o l o c a l o r i e n t a t i o n of S2 f o l i a t i o n and i s i n v o l v e d i n u p r i g h t medium folds  Assemblages  Qtz-Hnbd-Ep-Chl-Ab Chl-Qtz-Hnbd-Ep-Ab  Name  Qtz-Hnbd-Ep-Ab Meta-conglomerate w i t h minor Ep-Chl-Ab m a t r i x  Qtz Ab Muse Bio Ep Trem Hnbd  pre  D2  post  Unit E2b [E2c] {J143}  Colour  weathered - p a l e green t o r u s t y green grey f r e s h - green grey  Grain Size  f i n e t o medium  Mineralogy  Plagioclase(AnO) Quartz Chlorite Opaques  Textures  Coarsely l a y e r e d w i t h c h l s c h i s t , black t o green grey p h y l l i t e , and a p o p h y r o b l a s t i c m e t a - a n d e s i t e ; f o l i a t i o n i s best o u t l i n e d i n f i n e r g r a i n e d u n i t s ; c o n t a c t s are seen t o | | f o l i a t i o n ; u p r i g h t medium f o l d s o f f o l i a t i o n and c o n t a c t s are common  Page 152  68-45% 20-40% 10-10% 02-05%  Structural 6eology of Part of the Crooked Lake Area, Quesnel Highlands, B r i t i s h colunbia  [E4a] {J155}  Assemblages  Opaque-Chl-Qtz-Ab  Name  Chl-Qtz-Ab Meta-sandstone i n t e r l a y e r e d w i t h p h y l l i t e s , c h l s c h i s t , and p o r p h y r o b l a s t i c meta-andesite  Colour  weathered - p a l e green t o r u s t y green grey f r e s h - green grey  G r a i n Size  f i n e t o medium  Mineralogy  Plagioclase(AnO) Quartz Chlorite Opaques  Textures  Massive t o medium l a y e r e d ; c o m p o s i t i o n a l l a y e r i n g o f sandstone and p h y l l i t e a t high angle t o S2 f o l i a t i o n and i n v o l v e d i n medium t o t i g h t recumbant f o l d s ; f o l i a t i o n i s g e n t l y warped t o u p r i g h t medium f o l d e d  Assemblages  Opaque-Chl-Qtz-Ab  Name  Chl-Qtz-Ab Meta-sandstone w i t h minor grey phyllites  Page 153  70-40% 15-35% 10-20% 05-05%  structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British coluwbia APPENDIX B T h i s appendix c o n t a i n s Crooked Lake area.  a compilation  of  the s t r u c t u r a l  into  Fractures,  planar  Bedding,  the  Geographic c o o r d i n a t e s and a l t i t u d e s are g i v e n f o r t h e S t a t i o n  L o c a t i o n s i n d i c a t e d ( a l s o , see Geologic Hap, P l a t e I ) . divided  data c o l l e c t e d a t  and l i n e a r  fabrics;  the  Foliations,  and Cleavages,  The data, i t s e l f , i s g r o s s l y  planar  data  whereas,  is  subdivided  the  linear  data  s u b d i v i d e d i n t o T i g h t , Medium, and Open F o l d Hinges and General L i n e a t i o n s .  into is The  f o l l o w i n g i d e n t i f i c a t i o n codes a l l o w f u t h e r s u b d i v i d e d o f these 8 b a s i c c a t e g o r i e s :  FCT - f r a c t u r e  FH - f o l d hinge  QVN - q u a r t z v e i n i n g  FHS - hinge o f f o l d w i t h ' s ' vergence  KBB - k i n k band boundry  FHZ - hinge o f f o l d w i t h ' z ' vergence  CF1 - 1st o f a congugate f r a c t u r e s e t  FHM - hinge o f symmetric f o l d  BOD - bedding or c o m p o s i t i o n a l l a y e r i n g  LN - l i n e a t i o n  ENS - enveloping s u r f a c e o f f o l d s o f BDD  LNC - c r e n u l a t i o n l i n e a t i o n  FOL - f o l i a t i o n  LNS - smear l i n e a t i o n  DFL - f o l i a t i o n deformed by k i n k i n g  LNI - i n t e r s e c t i o n l i n e a t i o n  FLC - cleavage r e l a t e d t o f o l i a t i o n  LNR - rod l i n e a t i o n  APO - a x i a l plane o f open f o l d s  LNM - m i n e r a l l i n e a t i o n  APM - a x i a l planes o f medium f o l d s  LNV - hinge o f f o l d e d v e i n  APT - a x i a l planes o f t i g h t f o l d s  LNB - boudin l i n e a t i o n  CLV - cleavage  LNK - e x t e r n a l r o t a t i o n a x i s of k i n k  Page 154  Structural Geology of Part of the crooked Lake Area. Quesnel Highlands, British Colunbia Station Eleu. Long. Lat. [FRACTURE] ID Feet 120 -x'U52 -y'K IDStrDipDD o  o  [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [MEOIUK] [OPEN] [LIN] IDStrOipDD IDStrOipDO IOStrOipOD IOTrePlu IDTrePlu IDTrePlu IDTrePlu  oaoooooooooooaoaooooooooooaooaoooooaoaoeaooooooooaoooooooooooooooooooooooooooooaoeooooaoooooooooooooooDoooaooaaoooooiieoaDoo  J1 J2  3200 47.4286 14.3913 3200 47.2143 14.4130 FCT 70 90  J3 J4  3300 46.1429 14.4848 3S00 43.3571 14.5435  J5,5a  3550 43.2321 14.4891 43.6250 14.3804  J6  3550 43.1429 14.5000  J8  3300 43.75DD 15.4348  J9 J10 J11  3400 43.5536 15.2826 3450 43.3929 15.1196 3500 43.1786 14.934B  F0L171 85E F0L175 80E F0L172 85E FOL 3 75E FOL 90 21N 8DD158 601) F0L155 66U FOL158 60U 800172 BSE  BD0130 BBU  APO 42 35NU CLV 8 E5U  FH355 15  FH1I352 IB  LN 25 LNC329 LN324 LNS142 65NU FHS340 40 FH294 66 FHH32B 55 LN288 40NU FH313 25 FN295 30 36NU 66NU 60U  a V 52 S9NU CLV 62 29NU  16 71 46 20 15  FOL140 SOU APT 25 F0L146 76E 8PO 32 FOL120 90 APO 56 F0L113 02U APO 32 FOL110 90 AP0175 FOL121 90 FOL110 78NE FOL132 88NE FOL130 BBU F0L140 90 F0L142 54U FOL 158 70U FOL130 90 FOL125 85E F0L12B 60NE FOL126 57E BDD140 56SU FOL140 56SU CLV115 76NE FH292 45 FH286 45 FOL1ZO 70SU FH305 43 FN295 59 BDD180 56U FOL169 65U CLV170 55U F0L17B 65U F0L180 56U F0L1B5 67U F0L157 59U CLV137 85E LN314 35 F0L156 72U a v 72 74NU LNC274 60 FH2B5 60 FH335 70 FH198 15 LNI259 28 ENS 74 62N FOL 30 73NU APH133 90 FH274 33 LN284 8 ENS 93 67N FOL 72 69NU APN130 83NE FOL 76 73NU APO 14 3BU FH295 35 LN295 46 FOL 72 80NU APN102 85NE FH310 51 LN278 SB FOL 72 78NU APN130 64SU FHS284 48 LN310 48 FOL 90 88N 8PT1Z0 55SU FOL116 74SU RPH138 60SU2 F0L115 74U APK156 61SU F0L175 48U APH142 67SU F0L124 69SU FOL100 88E FOL 75 70NU FOL 22 79NU FOL 50 75NU FOL 88 83N FOL 84 84NU FOL 32 70NU FOL130 47SU F0L174 55U FOL122 6EU F0L104 B8NE F0L125 B2SU FOL 92 90 Page 155  structural Geology of Part of the Crooked Lake Area, quesnel Highlands. British Colunbia Station Eleu. Long. Lat. [FRACTURE] 10 Feet 120°-x'U52 -y'N IOStrOipDO e  [BEODIKG] [FOLIATION] [CLEAVAGE] [TIGHT] [NEOIUH] [OPEN] [LIN] IDStrDipOO IOStrOlpOO IOStrOipOD IOTrePlu IDTrePlu IOTrePlu IDTrePlu  oaaooooooooooooooooooooooooooooooooooooooooeooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo  312,13  3300 43.1071 15.0543  314  3500 42.9643 14.5326  315 J16  3550 43.9464 14.1413 0VN100 36N FCT132 BSE 3558 44.4634 13.8152 FCT 62 7BN  319  3600 45.0357 13.9565 FCT 74 B5S  ENS 28 49NU ENS 12 36SE ENS 90 48S  FOL12B 7EU FOL 92 40N FOL 96 S4NE FOL135 70U FOL 158 78U FOL 132 75U FOL148 74U FOL124 84SU FOL123 74E FOL 55 35NU FOL122 84SU FOL 85 45N FOL130 74NE FOL108 80NE FOL130 80SU F0L104 76NE FOL 129 64SU FOL149 66SU FOL144 60SU F0L14B 78SU FOL 82 66R FOL115 90 FOL129 85SU FOL101 60NE FOL 134 72SU FOL144 65SU FOL 95 58N F0L135 77SU FOL 78 40N F0L1D5 76NE F0L1D5 76NE FOL 3D 36NU FOL 00 7SNU F0L170 49U FOL136 72SU F0L141 70SU FOL184 83U FOL119 SO F0L145 60SU FOL162 57U FOL133 85U  APD150 76U APH16S 62U  FH1B2 50 FH2307 42  LN312 52 LN107 35  RPN118 6EU APH12B 76E APH125 B2E API! 20 56NU APR115 6BNE APH110 66NE 8PR105 64NE APH115 65NE BPH 92 521 APtl 60 34NU APN125 75NE APH 92 65N APH102 60NE APR 88 4SN APN118 88NE APH131 B4NE  FH2298 55 FH2313 41 FH2312 45 FH2305 50 FH2299 22 FHZ302 35 FH2311 40 FHZ321 30 FHZ295 39 FHZ290 33 FHZ285 30 FHZ290 36 FHZ310 45 FH22B3 35 FH2306 40 FHZ2S0 35  LNR306 43 LN309 70 LN299 41  FOL120 87U FOL 135 88E FOL123 75E FOL136 B5U F0L150 86U FOL144 BOE FOL127 86E FOL125 88E F0L145 83U F0L153 6BE Page 156  LN30E 32 FH128 56 LNH151 46 LRH113 63  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Coluwbia Station Elev. Long. Lat. [FRACTURE] ID Feet 120°-x'tfiZ -y N IOStrDipDD o  ,  [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [KE0IUH] [OPEN] [LIN] IOStrOipDO IOStrOipOD IOStrOipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu  oooooooooooooooooooooooooooooooooooooooooooooooooooooeooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo  J19 (cont.)  J21 J22  J23,24  J26 J27  J2B 329 J30  J31  J32 J33  F0L165 90 F0L165 B8U FOL165 B6E FOL153 85E F0L170 75U FOL153 SOU 3500 44.6071 13.8261 F0L160 63U 3300 43.7857 13.1733 FC1 48 2SRU 800170 63U FOL165 55U FOL360 60U F0L170 70U FOL185 65U F0L165 55U 4000 43.8036 13.2391 FCT 48 26NU FOL 0 SOU 43.9464 13.3261 F0L170 70U FOL1B5 65U BDD132 30 FOL125 66SU 3550 43.4643 14.2335 BDD13B 74U F0L135 B5E B0D157 68U FOL156 66U 36D0 43.6071 15.1304 ENS 66 35N FOL192 58U F0L175 63U F0L176 74U FOL147 77U FOL186 21U FOL186 50U F0L172 66U FOL150 70U FOL1B5 76U FQL1B0 B4U F0L173 75U 3700 43.7500 15.0217 F0L160 63U 3800 43.8929 14.9891 F0L174 SOU 3300 44.0714 15.0326 FOL165 83U FOL160 70U FOL15B 70U FOL1B2 55U F0L135 75U F0L162 85U 4000 44.2143 15.0378 F0L162 B5U F0L149 B5U FOL150 85U FOL155 75U F0L150 B5U 4200 44.4286 14. FOL14D SOU FOL155 56U ENS140 43NE F0L167 76U 3700 43.6071 14.7174 FOL170 65U FOL163 82E FOL170 72U F0L171 B6E FOL 15 B2NU FOL116 B5SU FOL163 70U FOL 173 85U F0L166 65U F0L165 68U  RPII153 68E  FH2336 26  LNC338 31  BPH153 68E  FHZ336 26  LNC338 31  8PM43 63SU APN138 74U  FHR3BB 30 FHH315 53  aV 75 53N APO 56 45NU APO 40 70NU  FNZ322 29 FH298 45 LN2B4 40 LN333 34  APR 88 76N APO 75 6BN  FH291 52  FH344 60 LN311 10  FH31B 68  FHS335 55 APO 82 66N APO 55 68NU APT154 62U aV 54 68NU APO 6B 60NU  Page 157  FH295 71 FH 10 70 FH302 68 FH344 69 FH333 31 FH323 62 FH335 43 FHS340 35  LN323 65 LN322 56 LNC293 46 LNC310 40 LNS327 15 UIC311 54 LNS342 3 LNS349 29 LNS355 28 LNC2S3 59 LNS324 42  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Station Eleu. Long. Lat. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEDIUN] [OPEN] [LIN] ID Feet 120°-x'U52 -y'N IOStrDipDD IOStrOipDD IOStrDipDD IOStrDipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu o  ooooooooooooooooooaoooooooooooooooooooooooooooooooooooooooeoooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo  J33  (cont)  J33a  3800  B0D170 E6U BDD148 84U BDD165 66U BD0152 B8U  FOL 5 77U F0L117 85NE FOL 5 83U F0L154 86U FOL183 74U FOL168 6BU F0L153 69U F0L15B BOE F0L175 B4E F0L171 B6E FOLIOS B4NE F0L175 74U F0L165 66U FOL175 79E F0L144 67U FOL150 Bill FOL IB 77U F0L157 67U F0L126 BINE FOL 11 BOU F0L175 64U FOL173 B5U FOL 98 86NE FOL148 6BSU FOL163 63U F0L1B5 65U F0L154 75U F0L149 70NE F0L148 84U F0L174 62U F0L144 70E F0L175 65U FOL 5 BOE F0L172 72U F0L162 70U F0L162 60U  J34  3980 43.7B79 14.8739  J35  4000 44.1071 14.6630  J36.3B  4150 44.4464 14.7065 4400 44.7321 14.7609  340  4400 45.1071 14.6957  J41  4500 45.17B6 14.7826  FOL1EB 79U  J42  3300 47.3929 14.4674  FOL177 82E FOL130 68NE  ENS 90 36N  F0L160 79U F0L164 B5U rOLISO 80E F0L140 BOE F0L154 7BU F0L160 85U FOL160 BSE F0L159 BOU F0L166 75U F0L167 85U  APO APH APO APO  56 76NU 32 S4NU 52 75NU 88 68N  APT 72 46R APH 48 65NU  APN173 72U AP0135 65NE  APO 9B 64N O.V153 98 APO 50 43N  Page 158  LNC315 LNC347 LNV318 LNC358 LNC352 LNS34B LNC344  59 39 50 60 42 42 66  FHH330 29 FHS268 62 LN324 FHS325 45 FH290 52 LNI340 FH331 64 LNR342 LN 30 LN325 LN32B  80 21 30 70 75 44  FH 11 44 FH342 67 FHS337 50 LN322 40 LN303 54 LN337 48 LN176 50 LN 14 87 LN300 70 FHS334 25 FHZ335 35 FH316 46 FHZ320 45  FHN342 36 FHH335 53 FHH326 50 FHH330 6B  LN334 66 LN336 30  FH2S5 72 LN334 40 LN341 25  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Station Elev. Long. Let. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [NEDIUH] [OPEN] [LIN] ID Feet 120 -x U52°-y N IOStrOipOD IDStrOipDD IDStrDlpDD IOStrOipOD IOTrePlu IDTrePlu IDTrePlu IDTrePlu o  ,  ,  ooooooooooooooooooooeoeoooooooeoooooooooooooooDOoooooooooooooooooooooooooooooeooooeoooooooooooooooooooooooooooooooooooooooo  342  (cont)  F0L15B BOE F0L170 90 FOL 10 B5U FOL 5 66U FOL170 63E  APO120 53NE  343  3S00 47.4107 14.6413  344  3000 46.6329 14.8043  BD0163 70E  345  4000 46.5000 14.8587  346 347 348  3180 44.0357 16.0000 3400 3700 46.2679 15.5652  349  3900 46.1964 15.4B91  350  4080 46.1429 15.3639  FOL 20 50E FOL 0 56E F0L156 70U FOL130 60E F0L172 6SU FOL143 83U FOL159 B4U FOL155 BBU FOL153 86E F0L143 90 FOL152 07E F0L15B 79U APO110 35S 800120 30NE FOL148 83NE APO 52 70NU 800135 40RE FOL 5 83E FOL160 74E F0L170 75E  351 4200 46.0714 15.2609 352,52a 4600 45.9643 15.1304 4500 45.9206 15.0652  FOL 140 85E  353 354 355  3600 3900 4000  45.2679 15.5978 44.7500 15.5435 44.7143 15.2283  356  4100  44.0750 15.1196  F0L145 83E ENS185 65NE F0L156 BBU F0L148 75E F0L143 SO ENS 14 64U F0L165 74U  357  4000  45.0179 15.2391  BOD 0 66U  359  3500  47.9021 14.8696  360 361  3400 3360  40.1607 14.3130 40.0000 14.5887  352 363  3500 3650  48.0000 14.7500 47.0929 14.7500  364  3600  47.5000 14.7935 FCT 75 85S  CLV155 55E  FHR144 22 LN150 5 LN150 20 LN135 50 LN 10 68  FH165 40 FH350 20 FH352 35 LN165 43 FH355 45 LNI356 34 LN150 33 LN153 10 LR148 5 FHS329 67 FHH 32 33  NPD118 86NE  F0L154 90 F0L162 75U FOL168 B2U F0L141 39E F0L178 55E FOL159 B3E FOL165 56E FOL180 E8E F0L16B 70E F a 7 79E F a 165 67E Fai78 74E Fa 20 55E F a Z BOE F a i 7 7 70U F a 2 BBU Fa 9 75E FOL1B0 BSU F a 4 73E F0L175 76U Fai65 26E  LN 2 44 LNI359 40 LN1B8 25 LN21S 35 FH114 50 LNS150 3 LNS317 33 LNS315 45 FH175 23 LN 33 15  LN334  FH338 55 FH31D 62 FH3ZB 42 FH344 48  LN340 LN 9 6 LN170 20  APO BPH RPn APR  Page 159  5 15U 30 77NU 53 65RU 40 5BNU  FH2 30 40 FH 1 10 LN340 10 LK345 52 FHS 12 36  Structural Geology of Part of the Crooked Lake area, Quesnel Highlands, British Coluwbia  Station Eleu. Long. Lat. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEOIUN] [OPEN] [LIN] ID Feet 120 -K'U52°-y K IOStrDipOO IDStrDipOD IDStrOipDD IOStrDipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu o  ,  000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000009000000000000  J64 365  J56  (cont) 3600 47.6250 14.5543  3550  J67 J68  41.8571 16.3152 F a 15 90 41.0179 16.2391  4350  J59 4950 J7D 5150  40.8758 16.3043  J72 3150  40.6607 16.4239 40.5357 16.4348 FCT158 B4U FCT 72 56S 37.6429 14.4783  J73 J74  3350 3600  38.8393 14.8152 38.8036 14.8587  J75 J76  3ED0 3850  3B.6250 14.8370 FCT162 75U 39.7500 15.3370 QVN105 60NE  J77  5000  J78  5550  F0L175 75E F0L162 70E F0L169 75E F0L164 72U FOL 16 6BE F0L175 73E FOL 5 90 BDD112 32NE F0L110 3BNE O.V144 57SU F0L112 32NE CLV13B 78SU F0L115 30NE F0L111 24NE 800115 70NE FOLIOS 33NE F0L115 70NE FOL104 34NE FOL 90 32N F0L115 22NE FOL 92 30N FOL 86 34N FOL 93 35N F0L101 35N FOL109 35N F0L127 42NE FOL 75 15N F0L100 40NE F0L115 31NE 800116 30NE F0L116 30NE BDO 82 22N FOL104 25NE ENS 92 18S FOL 98 34NE  F0L11D 35NE FOL105 52NE F0L121 45NE 41.5714 17.0217 KBB170 66E BDD150 7BE F0L103 SOME 41.9107 17.1522 FCT 98 3BNE ENS150 BBU FOL104 30NE OFL 50 60NU DFL 76 ZBSE OFL BO 43NU DFL 60 75NU FOL126 55NE F0L135 65NE F0L132 44NE F0L132 12NE FOL137 35IE FOL160 40E F0L143 75NE FOL130 3BNE FO.130 74NE F0L137 60NE F0L156 73SU F0L140 BONE FOL120 30NE F0L121 35NE 40.5357 16.6630 FCT 3B 80SU BDD100 74NE FOL120 37NE FCT 60 6DSE BDD16B 55NE FOLIOS 34NE  LH320 35  LN311 LN317 LN290 LN296 LN8293  17 16 9 6 9  FHS295 20 aV 82 26N APH B4 35N  FH320 32  AP0150 55SU  AP012B 66SU APT100 35N AP0170 42U AP0120 BONE APH120 60SU APH123 BBSU aV 92 22N APH158 70E APH 75 15N aV145 30NE CLV124 19NE aV 53 18NU a V 0 38U APH146 SINE  CLV 44 25NU a« 55 34NU  Page 160  LN315 22  FHZ295 10 FH305 18 LNR310 20  FH295 10 FH290 FH290 FH320 FH336  FH3DB 13 LN203 10 LN29S 5 LN301 16 FHZ311 21 21 LN294 4 14 LN292 0 LNR310 5 41 FHS335 20 LNK 5 34 23  LN335 22 LN330 22  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Station Elev. Long. Lat. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEDIUH] [OPEN] [LIN] ID Feet 120°-x'U52°-y N IOStrOipDD IOStrOipOD IOStrDipDD IOStrDipOO IDTrePlu IDTrePlu IDTrePlu IDTrePlu ,  oooooooeeoeaoooaooaoooooaoooooooooociooooooooooooooooooooooooooooooooooooaoooooooaaoaoooooaooooooooaooooooooaooooooooooooooo  J7B (csnt) 382  5800  383  6100  384  5900  J85  5500  JBE  5000  387  5000  088  5250  J8S J30  6200 6250  J91  5650  J92  5250  J83  5300  J94  5400  FCT 7B 17N BDD160 73U FOL100 31NE APH1E6 57SU F0L135 SENE QVN 57 3DNU F0L140 TONE 40.0536 16.5543 FOL109 44NE APO110 BOE FOL12S 60NE 39.1429 15.7826 0VN123 48NE BDD12S 31NE FLC125 31NE a«125 68NE 9VN114 20NE CF1166 03U CF2 50 B5NU 39.1964 15.7609 071177 B8E BDD11S 25SU FLC123 20NE O.V111 52NE CF2 70 86U B0D117 60SU FLC120 25NE FCT167 74E FLC147 3SNE 39.3393 15.6848 F a 2 83U 8001IB 25NE F0L115 34NE aV124 74NE FLC118 Z5NE FLC12B 20NE FLC134 30NE F0L107 ZONE 39.4464 15.597B QVN114 45NE FLC105 32NE avi70 64E Faifi5 73U FLC 95 30NE FOL 98 44NE F0L114 45NE FOLIOS 42NE F0L119 52NE F0L112 35NE F0L10B 40NE 39.7580 15.6522 FOLIOS 35SU AP0115 72SU FOL104 62NE FOL112 48NE FOL 105 58NE FOL BD 36NE 39.7500 15.7B26 Fa 2 B5U FLC109 44NE aV155 58E F0L114 42NE FOL 95 35NE F0L124 26NE 39.4464 16.0543 FCT170 6EU 800118 90 FLC 95 25NE aVIZO 3BNE 39.0893 15.7935 FCT164 90 800115 25NE F0L116 50NE aV138 3BNE F0171 78U OFL 71 55NU O.V13B 62NE KBB 10 B5NU FOL125 26NE CLV13B 53NE F0L116 3BNE aV132 56NE F0L115 25IE F0L110 Z5NE F0L115 39NE FOLIOS 35NE FOL120 2SNE 39.8893 15.7935 FOL116 30NE CLV116 7BNE FOL105 34NE 39.2679 15.5978 Fai65 98 FOL104 36NE APO140 75NE FOL102 45NE AP0130 52SU FOLIOS 55NE F0L106 49NE F0L109 42KE 39.0893 15.5000 FOL11B 36NE FOL110 46NE F0L111 20NE APH11B 62NE 39.0000 15.5109 F0L17B 20E APH116 90 Page 161  LN335 25 LN340 21 LN297 14  FH229S 50 FH315 15  LN306 3 LNB337 17  LN294 2 LN110 8 LN295 4 LN299 12 FH2B4 15 LN290 10  FHS295 10  LN114 2 LN296 3  LNK 16 50 LNI307 9 LN305 7 LNB 0 36 LN310 10 LN30D 0 LN120 2 LNR111 3 LN297 0 FHS315 30 FHS295 10 LN310 6 FH3D0 8 FH306 6 LN3D3 15  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Colunbia  Station Elev. Long. Lat. [FRACTURE] [BEODING] [FOLIATION] [CLEAVAGE] [TIGHT] [HE0IUT1] [OPEN] [LIN] ID Feet 1ZD -x'U5Z -y'N IDStrDipDD IOStrOipOD IOStrOipOD IOStrOipOD IDTrePlu IOTrePlu IDTrePlu IDTrePlu 0  0  000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000  394  (cont)  335  5700  38.6607 15.4565  33B  5650  36.6429 15.347B  397  5600  38.5357 15.2826  398  5600  3B.3929 15.3043 FCT 15 B3U  399  5600  3B.1B71 15.2283 FCT 12 72U FCT 11 B5SE FCT137 57SU  3100  5600  37.7679 15.1630  3101  5450  37.5000 15.1304  3102  5350  37.4107 15.1087  3103  5300  37.2580 15.1630  FOL103 38NE F0L114 50NE F0L13D 5ZNE FOLIOS 23NE F0L118 40NE F0L122 46NE F0L116 85SU FOL100 30NE AP0165 6BE FOL 95 32NE F0L115 32NE FOL110 43NE FOLIOS 25NE F0L122 50NE F0L111 41NE F0L115 4SNE FOL129 45NE F0L11B 32NE F0L120 SOKE FOL110 30NE RPH112 70NE F0L115 54IE RPH113 7BNE F0L119 42NE 8PH134 BOSU F0L124 TONE F0L124 52NE F0L125 4BRE F0L13D 36NE RP0120 74SU F0L121 40NE 8P0122 72SU F0L112 Z5NE RP0110 B3NE FOL110 4ZNE F0L151 19SU FOL 24 10NU FOL SO 30N FOL120 S6IE F0L116 55NE F0L111 30NE F0L12B 24SU FOLIOS 63NE RP0120 BOSU F0L119 60NE FOL130 65NE FOL120 60NE F0L121 60NE F0L120 54NE F0L134 48NE RPN125 76NE F0L128 4BNE F0L131 30NE F0L182 43E F0L134 25NE F0L14D 65NE F0L135 55NE F0L136 40NE FOL 95 11N F0L149 30NE FOL 15 SHU F0L136 55NE F0L112 62NE F0L11B 56NE  Page 162  FH345 30  LN310 12  FHSZSO 11 FHS2S6 12 FHS305 5  FHS305 10 FHS301 5 FHS305 8  FH296 7  FHS297 2  structural eeology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia Station Elev. Long. Let. [FRACTURE] ID Feet 120°-x U5Z°-y'N IOStrOipOD ,  [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEDIUH] [OPEN] [LIN] IOStrOipOD IOStrOipOD IOStrOipOD IOTrePlu IDTrePlu IDTrePlu IDTrePlu  OOOOOOOOOOOOOOOOOOOOOOOOOQOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO  J104  5100 37.1250 15.119B FCT177 62U  3105  4900  36.9021 15.1087  3106  5360  38.7500 15.2826  3107 3108 3103  5100 5300 5650  38.8214 15.2391 QVN152 66U 38.8571 15.3261 QVN 95 55NE 38.8750 15.5109 KBB175 71E FCT165 53U  3110  6100  3111  5200  3B.7321 15.6087 FCT180 90 FCT 72 52U 39.2143 15.4457 FCT170 BOU  3112  4920  39.3036 15.3913 FCT 12 84U FCT 10 76U  3113  4700  39.6071 15.5217  3114  4700  39.7500 15.5543  FOL140 36SU F0L135 36NE FOL130 TONE FOL120 76SU FOL152 46SU FOL125 49NE FOL120 50NE FOL123 40NE F0L127 16NE FOL136 53NE F0L121 57NE F0L114 90 F0L120 40NE F0L118 90 F0L114 35SU FOL125 30RE  r  APT 53 50NU APT BO 34N APT 10 25U APT 75 20NU APT160 5U APT118 42NE APH120 76SU RPK132 90 APH129 72NE APH136 90  FH342 45 FH303 24 FN31B 14 FH322 9 FH334 10 FH321 6  FH30B 10 FH309 11 FH308 FH380 FH311 FH309  aV126 60NE AP0130 90 F0L121 45NE APO 53 E5SE F0L100 55NE FOLIOS 36NE F0L13B 40NE FOL130 34IE CLV113 42NE FOL1S0 42NE FOL1DS 35NE a v i 1 4 52NE F0L112 34SU AP0114 7DNE FOL115 45NE F0L111 28RE OFL 64 40NU DFL 65 41NU F0L112 52NE FOL122 32NE FOL 96 35NE F0L115 1BNE  FH310 10  F0L122 52NE F0L114 34NE FOLIOO 38NE FOL119 65NE FOL11B 12SU FOLIOO Z5IE FOL 90 45N FOL102 45NE F0L105 45NE FOL142 52NE FOL155 25NE FOL120 44NE FOL102 52NE FOL 98 42RE FOL170 20NE FOL 95 SOME FOL115 68NE FOL 96 58NE F0L105 5ZNE FOL 94 55NE 800103 42NE FOL 93 35NE APH142 30ME  FH124 5  Page 163  FN 70 42  FH290 10 LNK 36 LN29B LNB318 LN 5 LIB290  FH10B 2  34 4 12 56 4  LN294 11  I  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia  Station Eley. Long. Lat. [FRACTURE] 10 Feet 1Z0 -x'lfiZ -y'N IOStrOipDD o  s  [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEDIUH] [OPEN] [LIN] IOStrDipDD IOStrOipDD IOStrDipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu  000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000  J114 (cant)  FH1ZB 1  3115 J11B  LNR310 13 FH 10 35 FH 1Z 35  J117 J11B  J119  J1Z0 J121 J1ZZ J142  J143 J144 JUS J147  F0L115 50NE APH12D 36NE F0L115 15NE F0L115 B5SU FaiOS 25NE F0L112 40NE FOLIOS 58NE F0L115 50SU 64Z0 3B.7500 16.0543 FOLIOS 25NE S9S0 37.5000 15.9457 ENS 5 64U APH 93 40NE APO 5 70E 6950 37.0357 16.1630 FOL 77 50NU HPH126 4ZNE Fa 90 41NE 6450 37.3393 15.6413 KBB170 7BE F0L114 63NE aV114 68NE OFL 47 72NU F0L115 45NE FOLIOS 49NE F0L116 60NE F0L114 49NE FOL101 36NE F0L110 46NE 600B 36.8036 15.4130 FCT175 70U F0L106 55NE F0L115 3BNE F0L112 52NE F0L115 55NE F0L110 50NE F0L115 45NE FOL105 31NE 5BZ0 36.9107 15.2717 F0L125 S2NE F0L120 56NE F0L126 50NE 5900 37.2500 15.3043 FCT176 82U F0L12Z S2NE F0L11B 45NE 6000 37.6071 15.3587 F0L115 46NE aVIZO 75NE F0L112 50NE 6920 36.6071 16.4239 FOL 89 6BN Fa 93 65NE F0L114 64NE Fa 92 46NE Fai05 74NE 70Z0 36.6071 16.5326 BOD 68 4BNU F a 92 60N 7000 36.5357 16.6304 Fa 73 32NU 7300 36.6786 16.9565 FCT11B 30NE 8DD150 83U Fai22 5SNE FCT113 45NE 7220 36.7500 16.7391 FCT 68 45NU BDD118 45NE F a 93 58NE AP0122 30ME BOD 95 73NE 8B0107 53SU  3149  7100  36.8036 16.5326  3150  6900 36.8929 16.4130  Fai03 35HE flPmOS 36IE F a 14 3BE AP0115 24NE Fa 24 B4NU FOL110 60NE Fa 46 54NU F a 34 5BIU Fa 6 64U FaiOS 50NE Page 164  FHS340 50 FH 5 45  LNZ96 10 LN30S 12  LN301 15 LN304 10 LN332 26 LNB 21 61  LN295 3  r  LN300 3  LN29B 9 LN270 4 LN 76 20 LN 7B 27 LN10B 3 LN116 0 LN307 40 FH290 6 LN 94 5 LN254 13 LN290 2B LN26B FH345 46 FH 30 18 LNZ95  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia Station Elew. Long. Let. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEOIUH] [OPEN] [LIN] ID Feet 120 -x U52°-y N IOStrOipOD IOStrOipOD IOStrOipOD IOStrOipOD IDTrePlu IOTrePlu IDTrePlu IDTrePlu s  ,  ,  ooooooooooaoooooooooooooooooooooooooooooooooooaoaooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooaooooaoo  3151  6730  36.6071 16.3043  3152  6600  36.3750 16.2935  3153 3154  6450 6450  36.2500 16.2935 F a 125 DONE 36.0893 16.3761 FCT 94 60N  3155  6720  36.1429 16.4674 FCT176 90 FCT 99 BON FCT107 58NE  3156 3157  7320  35.9286 16.4565 35.4643 16.6087  3158  7000  35.3393 16.5435  8D0125 75NE FOL 76 54NU F0L14B B5NE FOL150 50SU FQL177 22U F0L125 75NE FOL 15 4BU F0L115 72NE F0L102 56NE FOL 95 42N FOL130 80NE F0L125 B2NE F0L145 75SU FOL 0 30U F0L1S5 61U F0L165 35U F0L126 74NE FOL 96 65N F a 93 44N FOL104 50NE ODD 76 B6NU F0L107 68NE FOL140 45NE F0L14B 76NE FOL100 66NE F a i 0 9 501E F a 7B 66NU 800160 62NE F a i l l 64NE B0D14B 7BNE FaiTO B2E BOO 94 B3SU FQL114 62HE 800 7B 76SE FOL110 50NE BOD 30 40SE F0L140 65NE BDD130 65NE FOL110 54NE BOD 2 74E Fai05 42NE BB0136 25SU FLC115 30NE BD0129 60SU 800136 20SU 800130 40SU FLC110 69NE Fa 42 30NU  FHZ300 42 FH310 24 LN270 0 FH320 6 LN314 30  m 78 55NU AP0115 45NE AP0148 56NE  FH 75 32  APO 73 90 aV123 32NE  LN274 IB  aV140 90 APH112 45NE a v 06 44N a v 92 62NE aV113 64NE  FH 90 35 FH105 45  APH1Z4 50NE aVIlO 66NE  FH302 15  APD140 74SU  FH315 32  F a 96 52N  3159  6920  35.4821 16.3587  3162 3163  7000 6920  38.1071 16.6413 36.4286 16.597B  BOO 32 56NU  F a 94 30NE F a 95 43NE Fai56 6DSV F a 105 59NE F a 96 60NE  BOD 98 66NE F a 90 35N 800140 86RE F a 76 30NU 800 66 32NU FOL124 59SU FOL103 54NE F a 144 65SU F a 136 72SU F01103 44NE F a 78 40NU F a 40 24NU  APT 88 46N APT 80 42N APT 60 30NU APT 92 38NE APT100 40NE APT107 44NE APT SB 43NE APN130 DONE APH129 7BNE  Page 165  FH320 30 FH323 27 FH324 21 FH319 34 FH315 38  FH2B9 23 FH300 24 LN 0 35 FH3D5 21 FH300 24 FH307 33 FH305 25 FH314 IB FH323 3D  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Station Elev. Long. Let. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEOIOH] [OPEN] [LIN] 10 Feet 120 -x'U52°-y N IOStrOipOD IOStrOipOD IOStrOipOD IOStrOipOD IDTrePlu IDTrePlu IOTrePlu IDTrePlu D  ,  OOOOOOOOOOOOOOOOejOOOOOOOOOOOOOOOOOOOOOOOOaOOOOCOOOOOOODOOOOOOOOOOOOOOOOOOttOOOOOOOOOOOOOOOOOOOODOOOOOOOOOOOOOOOOOOOOOBOOOOOtt  3163  (cont)  3164 J165  7120 37.5000 1S.3B04 6700 37.7321 16.5000  3166  6620  38.3036 16.6087  3167  6620  38.2857 16.5326  3168  6450  30.0357 16.4348  3169  6320  3B.3214 16.1413  3170  6450  38.0714 16.0435  3171  6780  37.4107 10.0435  800110 70NE  000115 55NE EDO 65 40NU BOD 05 32NU  F0L125 7BRE FOL 60 3BNU FOL 95 44NE FOL 47 54NU FOL 75 50NU FOL B7 35NU FOL 33 41NU FOL 56 41NU FOL 70 41NU FOL 76 37HU F0L144 65SU FOL120 48NE F0L165 38U F a 95 47RE FOL 138 85NE F0L124 80NE FQL135 85SU F0L113 S4NE F0L125 84NE FOL 76 32IU F0L120 60NE F0L124 TONE FOL 97 60NE F0L173 70U FOL 60 52NU FOL 82 32NU FOL 72 48NU FOL 97 4BNE FOL 90 34N F0L115 62NE FOLIOS 39NE F0L125 35NE FOL110 63NE FOLIOO 28NE F0L110 47NE FOL 60 35NU F0L125 42NE F0L125 64NE FOL101 36NE FOL 05 38NU FOL 55 46NU FOL 96 45NE  BPH127 BORE 8PH115 72NE APK13B BONE  APO 5 75E  APT 78 40RU APT SO 36N  Page 166  FH 6 25  FH34B 36 FH343 40 FH330 35 FH316 28 FH346 45 FH334 40 FH340 30 FH327 38 FH335 35 FH305 30 FH335 44  Structural Seolooy of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia Station EleM. Long. Lat. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEDIUH] [OPEN] [LIN] ID Feet 1Z0 -x'U52 -y'N IBStrOipDD IOStrDipDD IOStrDipOO IOStrOipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu s  o  OOOOQOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOQOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO  RZ1  R22  43.7143 13.0435 FCT 65 64S FCT ZO 70NU FCT 58 81S Fa 64 BOS Fa 50 B8N Fa 48 BZS Fa 56 70S Fa 64 TBS Fa 62 73S Fa 51 65NU F a 71 80S Fa 61 71S F a 60 79N Fa 37 59S Fa 24 90 Fa 41 90 Fa 42 78N Fa 65 71S Fa 56 72S F a 76 76S FO 50 73N FCT144 45N Fa 40 65S F a 27 70S F0153 75E FCT133 65NE F a 55 90 F O 47 75S F O 75 59S Fa 70 90 Fa 64 47S 38BD 43.6964 13.0761 Fa 64 90 BDD155 6DU Fa 30 80S Fa 64 76S FCT 73 75S FCT 61 641 F a 89 SOS FCT 50 73N FCT 6B 75N Fa 50 56N FCT 56 65N Fa 76 B5N FCT101 58N Fa 94 701 FCT 76 90 FCT 69 BOS Fa 81 35S Fa 35 78N FCT101 72N FCT 76 41S FCT 52 46S Fa 69 60N FCT 66 54S Fa 69 6BN FCT 64 70S  3860  FGL155 61U FOL158 76U F0L1B1 B3U FOL164 67U F0L156 84U F0L167 75U FOL148 68U FOL 154 701) F0L153 73U FOL151 B2U F0L156 BOU FOL161 73U F0L161 63U F0L158 Bill F0L156 84N F0L154 BOU F0L156 5BU  FH336 10 FH359 15 FH350 18  LN338 IB LN331 B LN305 15 LN350 22 LN331 11 LN139 30  FOL147 BOU FOL163 65U FOL158 7SU F0L161 75U FOL161 61U FOL160 D7U FOL 160 85U F0L164 75U FOL 154 7BU F0L156 79U FOL 158 BOU FOL161 B5U FOL164 62U FOL154 SOU F0L153 8DU FOL155 90 FOL154 SOU FOL158 75U FOL160 65U F0L151 75U  FH318 25 FH323 14 FH335 20  LN336 13 LN 53 B LN325 15  Page 167  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Columbia Station EleM." Long. Lat. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEDIUH] [OPEN] [LIN] ID Feet 12D°-x US2°-y N IOStrDipDD IOStrDipDD IOStrDipDD IOStrDipOO IDTrePlu IDTrePlu IDTrePlu IDTrePlu ,  ,  OOOOOOOOOOODOOOOOOOOODOOOOOOODODOOOOOOOOOOOOOOOOOOOOOOOODOOOOOOOOOOOOOOOOOOOOOOOOOOeeOOaoOOOOOOOOOOOOaOOODOeiOOOOOOOOOOODOttO  RZ2  (cont)  FCT 35 60S FCT 63 SO FCT120 60S FCT 49 73S FCT120 BBS FCT 58 85N RZ3 6850 43.6786 13.1196 FCT142 22E B0D17S 70U FOL155 62U QVN 74 90 BDD155 60U FOLISO 70U FCT 82 SO FOL155 70U F a 95 84S FOL1S8 70U FCT10D 6SS F0L15B 68U FCT 98 54N FOL168 64U FCT111 90 F a 80 80S FCT 24 76SE F0L154 SSU R24 3BB0 43.5714 13.0870 FCT 59 B4S FCT102 B4S FOL159 73U F a 44 90 FOL149 5BU FCT1DB 90 F0L153 73U FCT 69 90 F a 152 7QU FCT 39 85N F a 152 SSU F a 50 75S Ftt140 70U FCT 50 84S F a 151 70U FCT 63 BSS FCT 25 BSE FCT 50 72SE FCT 45 7SE FCT 64 76S F a i 6 3 70U FCT 50 BOS RZ5 3810 Ftt164 SOU 00.106 90 F a 175 72U FCT135 BOU F a 163 61U F a 62 82S Fa 159 78U FCT 65 87S F a 161 BOU FCT 65 79S F a 164 60U FCT 45 85E FCT 80 828 Fai65 65U F a 160 63U FCT130 32N F a 160 73U FCT 90 80S FCT 56 SO F a 37 90 FCT 58 70S B0D164 60U F a 157 78U RZ6 3920 , F a 167 63U FCT 49 82S F a i s s BDU FCT150 36E F a 156 BOU F a 56 82S Fai61 68U FCT 22 90 FCT 76 61S Fai62 72U FCT 50 77S Fa 159 71U F a 159 73U F a 67 64S F a 161 B1U FCT131 30N FCT 41 BZE Fai66 76U F0L161 76U FCT 40 90 F a 168 75U F a 78 71S FCT 64 82S FaiS9 76U Fai64 85U FCT 36 90 Fai59 64U FCT 69 75S Page 168  LNH334 8 LN328 20 LN332 14  FH315 FH 8 FH316 FH322 FH340  FHZ322 34 FHZ318 68 FH328 38 FH33B 37  LNC320 35 LNC342 33 LN334 28 LN335 24  25 FH3Z7 42 27 FHZ355 36 48 FHZ337 49 15 FH234S 50 25  LNH338 14 LNC345 16 LN330 27 LN341 10 LN337 32 LNC337 29  FHZ346 30 FH30B 40  LN337 24 LKH341 25  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia  Station Elev. Long. Lat. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [NEDIUH] [OPEN] [LIN] ID Feet 120 -x U52°-y'N IOStrOipOD IOStrOipOD IOStrOipOD IOStrOipOD IDTrePlu IDTrePlu IOTrePlu IDTrePlu o  RZG  (cant)  RZ7  4000  R2B  4050  R29  3360  RZ10  3S0D  R211  3820  ,  FCT 61 85S FCT 28 3D  FOL17D 60U FOL162 76U F0L159 5SU F0L171 S1U F0L167 70U FOL158 80U FOL160 SOU F0L160 75U FOL165 7TJU F0L1S2 BBU FOL166 75U  FHZ325 45  43.3214 13.2826 FCT 54 BOS FCT 25 90 F a 91 611 FCT105 90 FCT 3B SO F a 2B 90 F a 45 73S F O 57 67S F a 41 90 ENS 65 7QNU FOL 45 65NU FCT 68 70S FOL 19 60U F a 35 90 F a 80 7SN FCT105 63N F a 38 44N FCT 59 55S Fa 63 46N 42.9643 13.2826 F a 72 65NU F a 66 40N FCT148 75U F a 18 52H F a 30 65N F a 15 83N F a 15 86N 42.9464 13.22B3 FCT12B BON F a 43 66U F a 60 65S FCT13B 90 F a 75 SO F O 45 90 FCT15D B5S 43.0000 13.2065 FCT166 85SU F a 8 90 FCT143 70S FCT161 05U FCT142 90 FCT 90 55S FCT133 90 F a 44 65S FCT 28 55SE F a 53 BBS FCT 50 B4U F a 83 5BS FCT 70 66S F a 77 4SS FCT 57 62U FCT 54 SOSE F a 66 DOS FC7113 67N FCT125 SON FCT 58 BOS  43.0000 13.1196 F a 64 60S 43.  F0L164 75U FOL176 68U F a 5 5BU F0L1G8 70U F a 3 sou F a 0 65U F a 160 F a 45 Fa 5 FaiTS  68U 68U 85U 85U  a v 19 8BNU  Fai65 85U  FOL 160 85U F a 0 B5U F a i 7 5 BOE F a 46 S8SE F a 25 BSE Fa 22 40U F0L171 B1U FOL165 64U F a 165 70U F a 154 76U F a i 5 6 05U F a 168 67U FOL161 72U F a i 6 0 75U FOL155 75U FOL162 90 F a 0 76U Fai71 70U F a 170 70U F a i 6 0 82U Page  FH2326 55 FHH3D2 70 FH284 50 FH295 57 FH326 43 FHZ329 46 FH353 70 FH2312 50  LNK320 60  FH312 47 FH3S5 50 FH318 49 FH2328 SB FHZ337 67  LNH324 37 LNH326 36 LNH332 37 LN330 33 LNH323 27 LNH335 35  LNK323 46  \  FH332 50 FH325 50 169  LNM10B 15  structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia  Station Elev. Long. Lat. ID Feet 120°-x'U52 -y'N s  [FRACTURE] IDStrDlpOD  [BEDDING] [FOLIATION] IDStrDipOO IOStrOipOD  FCT 56 57S FCT 55 48S FCT 69 39S FCT 60 43S FCT 57 42S FCT 56 33S FCT 97 4BS FCT102 SOS FCT1D2 52S FCT105 70S FCT 93 SIR FCT 66 66S FCT 69 75S FCT 60 70S FCT 74 75S FCT116 39R FCT 67 80S FCT 56 76S FCT 63 B2S FCT 73 60R  FOL158 79V F0L170 03U F0L157 B3U FOL164 B6U FOL159 BOU F0L149 BOU FOL165 02U FOL171 73U FOL169 B1U FOL160 90 F0L160 78U F0L140 98 F0L163 85U FOL 165 84U FOL164 82U FOL164 BOU F0L169 65U FOL 159 7SU FOL 153 86U F0L164 BOU F0L151 81U F0L171 75U F0L177 7BU FOL 155 BOU FOL 154 B2U FOL140 7SU FOL165 84U F0L1S7 BBU FOL151 80U F0L142 90 FOL169 85U F0L151 B7U F0L161 BOU FOL135 05U F0L144 85U FOL 0 79U FOL 3 B3U FOL157 79U F0L173 90 F0L153 B5U FOL153 73U F0L164 BOU F0L171 7BU F0L16B 78U F0L175 90 FOL162 72U F0L168 65U FOL184 86U FOL169 70U F0L154 BBU F0L164 78U FOL 167 BOU F0L162 85U F0L172 28E  [CLEAVAGE] [TIGHT] [NEDIUH] [OPEN] [LIN] IDStrOipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu  Page 170  FH339 25 FH300 26 FH163 25 FH ID 8  LRC340 40 LHC346 44 LRK352 33 LHH319 35 LRK336 20 LRH313 48 LRK320 40 LRR316 42 LNH336 14 LRR333 13  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia Station Eleu. Long. Lat. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEDIUN] [OPEN] [LIN] 10 Feet i20 -x'U52 -y'N IOStrDipOO IOStrDipOO IOStrDipDD IOStrDipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu o  D  oooooDODooooaoaoooDeioooooooaooooooooooooooDooooooooooooDoooooooooooooDoooooooooaoooooooooooooooooooaoooeoQoaooooooQoooooooo  RZ11  (cont)  FOLIE? 72U FOL16E SSU FOL155 73U FOL1E2 75U FOL162 64U FOL161 E5U FOL158 84U FOL155 67U FOL 158 E5U FOL166 78U FOL162 SSU FOL 164 64U  Page 171  structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Coluwbia APPENDIX C  A t - a l p h a p l o t i s generated by measuring f i r s t t h e r e f e r e n c e hinge t h i c k n e s s ,  (tO),  f o l l o w e d by sucessive l i m b t h i c k n e s s e s ( t a ) away f r o m t h e hinge toward t h e f o l d ' s point;  inflection  ( t a ) i s a perpendicular thickness  between t a n g e n t s t o t h e upper and lower s u r f a c e s o f t h e f o l d ; next a p e r p e n d i c u l a r t o t h e a x i a l surface i s constructed t o i n t e r s e c t the tangent p o i n t of e i t h e r surface of the f o l d .  The  i n t e r s e c t i o n angle i s t h e angle between t h e t a n g e n t l i n e and t h i s ' c o n s t r u c t e d p e r p e n d i c u l a r * . This angle(a) i s p l o t t e d against the r a t i o of l i m b t o hinge t h i c k n e s s e s ( t a / t O ) .  t - a l p h a p l o t standard forms  t  = t(mm)/to(mm)  1.6  1.2  C l a s s 1a a C l a s s 1b  -  C l a s s 1c • Class 2 • Class 3  10  20  30  40  50  60  Alpha = a°  Page 172  70  80  90  Structural geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia OIIT-STITIM-EPISOIE  ALPHA  TABU  51 80  .88 .32  81 62  .25 .29  43 78  .93 .50  60  .43  82  .32  82 82  .25 .29  84 89 87  .21 .21 .18  80  .29 .14 .14  ILPII  TAW  UNI  79  .36 .19 .57  Till)  ALPHA  TAW  61  .50  63  .84  75 84 86  .36 .36 .38  68 88 88 83  .19 .16 .16  11 FOLI FOBIS  Snowshoe-J72-01  $mwshoe-J74-D1  82 82 SnoBshoe-J74b-01  «irtler-RZ6-81  86 83 88  .14 .18 .14  87 85 83 81  .18 .09 .07 .07  83 84 85 68  .27 .21 .20 .20  18 50 5  1.08 .92 1.00  22 41 48 46 3 5 7  83 88  64  .12  1.00 .92 .63 J5 1.06 1.22  0 10  1.60 .62  1.22  20  .94  ...12 FOLI FOIIS  Phyllite-J57-D2 (open)  Phjfllit8-J40-D2 (open)  Page 173  66 88  .22 .17  84 86  .52 .28 .26  66  .23  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Colunbia BlIT-STiTIOi-EHStHE  IIHI  TMU  ILHI  THU  Phyllits-J40-02 (opso)  10  1.00  29  .82  (continued)  22 18  .89 1.00  36  .71  33  1.00  40 13  1.00 .90  14  .94  26 20 20  .90 .90 1.00  32 25 30  .81 .56 .94  30  .90  8  12 94  1.00 1.00  12 30  .88 1.00 1.14  73 16 38  .75 1.80 1.13 1.25  52 9 29  1.29 1.00 1.00  45  .08  52  .86  77 77 75 66 71 80 85 60  .29 .33 .46 .87 .42 .48 .54 .87  69 74  .87 .67  Phyllite-J89-D2 (open)  SnoHshoe-RZ8-D2 (open)  80 Phyllite-J41-D2 (nediun)  58 59 41 74 48 58 81 63 87 63 50 37 80 78 75 65 55 55  Phyllite-J5-02 (nedim)  51 34 34 69  .50 .70 .75 .50 .90 .65 .60 .50 .45 .65 .85 .95 .45 .55 .60 .75 .70 .75 .85 .95 .95 .71  Page 174  «.»••  TtBU  15  1.00  20 49  .91 .64  53 33 47 54  .45 .82 .82  61 59 44  .67 .50 .50 .44 .50 .83 .83 .89  48 49 41 40 23  .82  ILWi  TI5U  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia ttHi  TUB  .62  74  .86  78 63  .57 . 66  76 38  .53 . 93  81  .57  66  .87  81  .48  81  .73  85  .43  62 74  .93  40 56 73 67 79 81 31 42 48  .94 .76 . 67 .67 .39 J3 .93 . 83 . 78  BlIT-STITIOI-EPISOIt  ILPH  Phyllite-J5-62 (nediun)  76  (continued)  «ntler-8Z8-D2 (nediun)  Antler-R25-02 (nediun)  Snovshoe-R210-02 (nediun)  RnUer-R27-02 (nediun)  Phyllite-J28-02 (tight)  TMU  21 43  .92 .83  55 62  .67 .58  65 85 19 42 20 43  .58 .42 1.17 L08 1.25 1.13  58 60 62 62 15 48 51 61 63 89 66 61 34 77. 44 53 57 61 80 20 29 25 88  1.08 1.06 1.00 1.08 .88 .75 .83 J5 .78 .61 . 58 .81 .94 .39 . 90 . 76 . 66 .59 .52 1.60 .97 .97 .64  62 66 70  Page 175  ILWI  TIIU  ILPM  TAIU  M  .75 .54 .46  48 57 35 60 89 74 79  . 65 . 84 . 65 .78 .48 .33 J3  29 41 34 54 54 81 61  1.80 .78 1.06 . 72 .64 .81 .58  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British coluwbia 0IU-STiTI0H-EHSOBE  ILMI  TIM  Phyllite-J28-02 (tight)  66  .43  (continued)  SO 31  .79 .93  32 50 60 60 64  .93 .86 .84 .50 .43  64 82 85 60  .50 .43 .56 .71  65 71 77 76  .57 .38 .29 .21  70 71 74  Phyllite-J117-62 (tight)  73 74 60 65 75 79 Phyllite-J36-02 (tight)  ILMt  TtlU  .78  63  .55  .47 .39 .37 .37 .88 .44 .44 .42  74 76  .36 .36  79 78 75 77  .36 .73 .38 .45  30 62 66 66 71 73 73 69 73 73 74  .98 .71 .49 .39 .35 .33 .33 .61  74 74  .27 .25 .24 .22  78 78  .43 .33 .27  Page 176  ALPWW  THU  tLMi  TIIU  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia wn-smiw-ErisoiE  nm  TIIU  Phyllite-J38-D2 (tight)  76  .18  (continued)  60  .16  80  .18  80 7!  .14 .62  83  Phyllite-J28D-D2 (tight)  Phyllite-J41b-D2 (tight)  Bntler Cress Section (The Basset-Stark 02 Pair Cross Section 1 Plate 3)  nm  TIIU  UPH  THU  78  .27  83 79 79  .33 .29 .29 .33  80 80 75  .19 .23  76  .31 .23  79 78  .29 .87  78  .27  85  .23  85 83  .29 .29  20 55  .98  74 62 51  .56 .34  52 58  85  .75 .56  .31  58  .82 .65 .52  88 67 58 57 68 60 72 72  .55 .52 .52 .48 .75 .56 .44 .44  54 05 00 65 54 54 56  .33 .33 .59 .48 .42 .44 .45  62 65 47 77 84 82 79  .50 .43 .78 .55 .40 .35 .30  78 60 33 38 41 51 52 53 54 53 54 54 55 63  .44 .44 .88 .83 .92 .78 .69 .66 .64  80  .  41 55  .63 .63 .63 .64 .82  41 59 78 78 78 77 76 78 75 73  .91 .75 .92 .72 .57 .49 .45 .42 .40 .30 .38 .35  .58  74  .34  Page 177  urn  TIIU  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia MIT-STITIOI-EPISOBE  IIMI  TilU  It'll  Antler Cross Section  71  .48  75  .34  74  .34  (continued) Phyllit8-J98-D3  TtlU  ALPII  TIIU  M.HI  TIIU  1.80 .80  28  .95  26  .03  34  .93  28  32  .79  34  .75  47  .71  22 38  .92  27  .93  55 64  .92  40  .88  .90 .68  56  .80  70  .80 .60 .90 .60  79 42 59 63 Phyllite-J104-03  Pnyllite-J117-D3  38  .90 .08  43 43  .03 .75  44 48 43  .80 .70  40 55  .03 .87  56 57 50 54 40  .60 .60 .67 .67 .50  50 52 33 60 48  .42 .50 .09 .56 .78  Page  178  .60  61 82 84  .50  .70  Structural seology of Part of the Crooked Lake Area. Quesnel Highlands, B r i t i s h Coluwbia APPENDIX D Stereophotos of v a r i o u s f e a t u r e s a t Crooked Lake  P l a t e 5a.  Chl-hnbd-plag m e t a - d i o r i t e w i t h s c h i s t ( A n t l e r ) {DIR-325,L0C-RZ3}  P l a t e 5b.  Cross-fractured chl-hnbd-plag meta-diorite; fractures f i l l e d e p i d o t e , q u a r t z , and magnetite ( A n t l e r ) {DIR-335, L0C-RZ3} Page 179  interlayered/interfolded qtz-chl  with  Structural ecology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia  P l a t e 5c.  Q t z - c h l - h n b d s c h i s t w i t h i n t e r l a y e r s o f q t z - p l a g - e p meta-wacke show t i g h t t o i s o c l i n a l f o l d shapes ( A n t l e r ) {DIR-350, L0C-RZ6}  P l a t e 5d.  Red sandstone c o n t a i n e d w i t h i n p h y l l i t e i s open t o medium f o l d e d ; note cohesiveness o f sandstone (as opposed t o severe d i s r u p t i o n o f p h y l l i t e by S2 f o l i a t i o n ) (Crooked Lake P h y l l i t e ) {DIR-350, L0C-J52}  Page 180  that  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunpla  Page 181  Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia  Plate 5f.  P l a t e 5g.  Phase one i s o c l i n e o f c h l - h n b d s c h i s t ( A n t l e r ) {DIR-350, L0C-RZ6}  and  q t z - p l a g - e p meta-wacke  I n c l i n e d phase two medium f o l d s i n musc-plag-qtz s c h i s t {DIR-320, L0C-RZ8}  Page 182  (Snowshoe)  Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbla  P l a t e 5h.  Plate 5 i .  U p r i g h t phase two medium ' c l o c k w i s e - v e r g e n c e ' f o l d i n c h l - p l a g - h n b d s c h i s t ; note p o s s i b l e t i g h t f o l d forms i n v o l v e d i n upper hinge o f f o l d ( A n t l e r ) {DIR-335, L0C-RZ5}  U p r i g h t phase two medium t o t i g h t f o l d o f p h y l l i t i c s i l t s t o n e in p h y l l i t e m a t r i x ; f o l d appears t o be r o o t l e s s (Crooked Lake P h y l l i t e ) {DIR-330, LOC-J33}  Page 183  Structural ecology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia  Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Columbia  P l a t e 5k.  Recumbent t i g h t phase two f o l d r e f o l d e d by upright medium f o l d (Eureka Q u a r t z i t e ) {DIR-315,L0C-J104}  Plate 51.  U p r i g h t steep p l u n g i n g phase f o u r f o l d s i n Domain 1 t i g h t phase two f o l d s are present (near bottom l e f t i n photo) {DIR270, L0C-J33}  Page 185  phase t h r e e  

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