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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 . S c , M c G i l l U n i v e r s i t y , 1977 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE DEPARTMENT OF GEOLOGICAL SCIENCES We accep t t h i s t h e s i s as con fo rm ing t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA March 1986 9 C o p y r i g h t 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 the boundary o f the Omineca C r y s t a l l i n e B e l t and the Intermontane B e l t o f t he Canadian C o r d i l l e r a , has been examined w i t h c lose a t t e n t i o n being pa id t o the d e t a i l e d s t r u c t u r a l r e l a t i o n s o f the f i v e l i t h o l o g i e s t h a t comprise t h i s map area - the l a t e Pro te rozo ic Snowshoe Formation, the l a t e Paleozoic A n t l e r Formation, Upper T r i a s s i c t o Lower Jurass ic 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 , here in named the Crooked Lake P h y l l i t e and the Eureka Q u a r t z i t e , r e s p e c t i v e l y , and the Upper T r i a s s i o t o Lower Jurass ic Takla Group. These u n i t s form a normal s t r a t i g r a p h i c succession w i t h respect t o each o ther , though g iven data suggests f a r more complicated i n t e r n a l r e l a t i o n s f o r each o f t he f i v e u n i t s . The major contacts , where exposed, were seen t o be cont inuous 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 , sharp ly p lanar ( t o somewhat g rada t i ona l i n the case o f the Takla base), and occas iona l l y associated w i t h m y l o n i t i c f a b r i c s . These sur faces may represent 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 est imates 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 progressive deformat ion o f t he Crooked Lake rock u n i t s inc lude bedding sur faces and composi t ional l aye r i ngs , f o l i a t i o n s and cleavages, c renu la t i ons and other l i n e a r s t r u c t u r e s , minor f o l d forms and f o l d i n t e r f e r e n c e pa t te rns , and f r a c t u r e se ts . The f i v e d i s t i n c t se ts o f deformat ion f e a t u r e s t h a t represent t h i s t i m i n g sequence are the f o l l o w i n g : i s o c l i n a l , i n t r a f o l i a l , r o o t l e s s f o l d s o f composi t ional l a y e r i n g found e x c l u s i v e l y i n t he Snowshoe and A n t l e r Formations (D1), open t o t i g h t f o l d s o f bedding, compos i t iona l l a y e r i n g , e a r l i e r f o l i a t i o n s , and major contac ts and a pervasive mica/amphibole f o l i a t i o n (D2 r e l a t i v e t o Snowshoe and i i Structural Beoloqy of Part of the Crooked Lake Area. Quesnel Highlands. British Colunhia A n t l e r ) , up r i gh t open t o medium f o l d s o f e a r l i e r sur faces and major contac ts (03) , gent le t o open f o l d s and k ink f o l d s o f pervasive D2 f o l i a t i o n and composi t ional 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 sets (D5). The metamorphic h i s t o r y o f t he Crooked Lake rock u n i t s has been deduced f rom extensive microscopic examinat ion o f t e x t u r e s and minera l assemblages. Bar rov ian- type metamorphism accompanied the f i r s t t h ree deformat iona l episodes; the f i r s t event may have reached amphibo l i te grade, the second episode reached temperatures o f 500-575° a t pressures o f 4-7 kbars ( f rom e q u i l i b r i a o f p e l i t i c and maf ic assemblages), and the t h i r d approached on ly the lower t o middle greenschist grade. Appendices have been inc luded summarizing rock d e s c r i p t i o n data, s t r u c t u r a l data, f o l d form data, and stereo-photography o f prominent s t r u c t u r a l f ea tu res . i i i Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Columbia TABLE OF CONTENTS PAGE ABSTRACT i i FIGURES v i TABLES x i v PLATES xv MINERAL ABBREVIATIONS x v i i ACKNOWLEDGEMENTS x i x I INTRODUCTION Locat ion and Access 1 Physiography and G l a c i a t i o n 1 Previous and Current Work 4 I I GENERAL GEOLOGY Regional Geology 7 Local Geology 11 I I I STRATIGRAPHY I n t r o d u c t i o n 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 IV STRUCTURE I n t r o d u c t i o n 37 Maps and Cross .Sections 40 Domains 41 Phase One 44 Phase Two 48 Phase Three 57 Phase Four 67 Late B r i t t l e Phase 67 i v Structural Geology of Part of the Crooked Lake area. Quesnel Highlands. British Coluitbia S t r u c t u r a l Summary 69 V METAMORPHISM I n t r o d u c t i o n 74 Quar tzo-Feldspath ic 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 V I I CONCLUSION 104 V I I I LIST OF REFERENCES CITED 107 V I I I APPENDICES A - Rock Desc r ip t i ons 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 Fo ld Form Data 172 D - P la tes 5 ( a - l ) - Stereophotos 179 v Structural Geology of Part of the Crooked Lake Area, quesnel Highlands, British Colunbia FIGURES FIGURE PAGE 1. Locat ion of the Crooked Lake Map Area i n e a s t - c e n t r a l 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 ex ten t o f the map area a t Crooked Lake (s tudy areas of o ther Masters ' s tudents a lso shown) . . 3 3. D i r e c t i o n o f i c e movement o f Fraser I ce Sheet and l a t e i c e re-advances i n Cen t ra l B r i t i s h Columbia ( f rom Tipper 1971, p. 39) 4 4. G l a c i a l v a l l e y s t y p i c a l o f the nor theastern slopes o f Eureka Syncl ine 5 5. Tecton ic subd iv i s ions o f the Canadian C o r d i l l e r a showing present study area (adapted f rom Tectonic Assemblage Map o f the Canadian C o r d i l l e r a ; T ipper e t a l . 1981) 8 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 the Quesnel - North America suture zone. (F igure 4 o f O k u l i t c h 1984, p. 1181) 10 7. Contacts o f t he Crooked Lake rock u n i t s a. Panorama o f the southwest s ide o f Eureka Sync l ine ; , upper and lower con tac ts 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 contac t zone i s assumed f romK.V. Campbell (1971) {DIR-045} 14 b. Southwestern Crooked Lake P h y l l i t e / T a k l a contact zone as mapped {DIR-045} 15 c. Mapped contac ts between Crooked Lake P h y l l i t e and Takla i n the nor theastern contac t zone ; note poss ib le p h y l l i t e i n f o l d a t t op r i g h t re F igure 16d {DIR-318} 15 8. 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 musc-quar tz i te t y p i c a l o f the Snowshoe Formation i n the Crooked Lake area <DIR-350,LOC-RZ10} 17 9. Snowshoe/Antler con tac t a. Sharply de f ined contac t between Snowshoe Formation (below) and A n t l e r Formation (above) {DIR-030,L0C-J112} 19 v i Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia FIGURE PAGE b. 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 the contact between the 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 igure 12 {DIR-020,L0C-J114} 19 10. Near ly cont inuous 150 meter s e c t i o n o f the A n t l e r Formation bounded top and bottom by exposed contac ts (shown) {DIR-320} 22 11. Summary o f t he 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. 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 lag -ch l -hnbd s c h i s t (dark u n i t ) 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} 26 13. Micaceous q u a r t z i t e w i t h pervasive p l a t y t e x t u r e ; boudined and fo lded quar tz v e i n i n g i s a common f e a t u r e i n t h i s u n i t {DIR-062, LOG-J94} 28 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 rong f o l i a t i o n and d iscont inuous, transposed l a y e r i n g ; note t i g h t 02 f o l d a t upper r igh thand corner {DIR-020, L0C-J88} 29 15. Summary o f t he 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 the Takla Group rocks a. F o l i a t e d ch l -hnbd-p lag M e t a - d i o r i t e w i t h lenso id /sphero ids o f p lag -ch l -ep d i r e c t e d along the main f o l i a t i o n (S2) {DIR-100, L0C-J59} 34 b. Mat r ix -suppor ted b recc ia w i t h d i o r i t e and massive hornblende c l a s t s elongate i n t he d i r e c t i o n o f the main f o l i a t i o n (S2) {DIR-090, L0C-J60} 34 c. C las t -suppor ted 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 longat ion i n t he plane o f the main f o l i a t i o n (S2) {DIR-335, L0C-J144} 35 d. Folded contact (shown) between vo lcan ic 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 the 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 he Takla Group rocks {DIR- 318, L0C-J163} . . . 35 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 the Crooked Lake area; Domains I and I I are separated by the v i i 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 contac ts shown as heavy dashed l i n e s 39 18a. Contour p l o t s o f poles t o S2 f o l i a t i o n s f rom Domains I & I I (contours represent 0 , 5 , 1 0 , 1 5 , 2 0 . o f po in t s per 1 * s terebnet area) 42 18b. Contour p l o t s o f poles t o composi t iona l l a y e r i n g (bedding?) and envelopping sur faces o f D2 f o l d s (contours are 0 ,5 ,10* per 1% area) 43 19. Qtz-p lag-ep subun i ts i n ch l -q tz -hnbd s c h i s t show t i g h t l y f o lded and r e f o l d e d forms ( o u t l i n e d ) {DIR-345, L0C-RZ6} 45 20. I s o c l i n a l f o l d c losure i n v o l v i n g composi t ional l a y e r i n g o f qtz-musc marble and p lag-musc-b io-q tz s c h i s t {DIR-330, L0C-J74} 45 2 1 . 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 poles t o a x i a l sur faces o f D1 f o l d s f rom both Domains b. Equal-area net p l o t o f D1 f o l d hinges f rom both Domains c. t - a l p h a p l o t o f 01 Fo ld Forms Snowshoe J72, J74, J74b, A n t l e r RZ6 (see Appendix C f o r exp lanat ion o f f o l d form curves) 22. Equal area net p l o t o f poles t o p lanar measurements f rom a s i n g l e S2 f o l i a t i o n sur face a t RZ11 i n the 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 sur faces across the area 23a. Upr ight 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 ; the s igmoida 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. Upr ight t i g h t s i m i l a r f o l d t runca ted on the r i g h t aga ins t p lanar 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 (curves expla ined i n Appendix C) b. Medium f o l d s a t J41, J5, RZ5, RZ6, RZ7, RZ10 49 50 50 v i i i Structural Geology of Part of the Crooked Late Area. Quesnel Highlands. British Coluwoia FIGURE c. T igh t f o l d s f rom J26, J117, J36, J26b, J41b d. Basse t t /S ta rk p a i r taken f rom P la te 3, Cross Sect ion 1 25. 02 f o l d elements f rom 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 rom Domain I (0 8. 10* per 1% area contours shown) b. Poles t o S2 a x i a l planes o f minor f o l d forms f rom Domain I I (0,10,20,30% per 1% area contours shown) c. L2 f o l d hinges f rom Domain I (0 ,5 ,10 ,15 , * per 1 * area contours shown) d. L2 f o l d hinges f rom Domain I I (0 ,10 ,20 ,30* per 1 * area contours 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 form) {DIR-345,L0C-J171} . . . 27. I n t e r f e r e n c e 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 th ree f o l d s ( t o l e f t near quar tz ve in ) {DIR-317, L0C-J117} 28. Upr igh t open D3 f o l d i n g of An t le r /Eureka contact {DIR-325, L0C-J102} 29. D3 cleavages and c r e n u l a t i o n s f rom Domains I & I I shown as contour p l o t a. Poles t o S3 cleavages f rom Domain I (0 & 10* per 1 * area contours shown) b. Poles t o S3 cleavages f rom Domain I I ( 0 , 5 , 1 0 , 1 5 * per 1 * area contours 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 rom Domain I ( 0 , 5 , 1 0 * per 1 * area contours 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 rom Domain I I (0 ,10 ,20 ,30 ,40* per 1 * area contours 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 poles 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 contours 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 rom Domain I I ( 0 , 5 , 1 0 , 1 5 , 2 0 * per 1 * area contours shown) o ix Structural fieologw of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia FIGURE PAGE c. t - a l p h a p l o t o f D3 Fo ld Forms C. L. P h y l l i t e J98, J104, J117 (curves expla ined i n Appendix C) 60 31a. Combined data p l o t (equal area) t o show t y p i c a l spread of 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 rom Domain I (D1 f e a t u r e s inc luded) 61 31b. Combined data p l o t (equal area) showing r e l a t i o n s h i p between D2 and D3 fea tu res i n Domain I I a long upper and lower A n t l e r contac ts (J85—>J114) 62 31c. Combined data p l o t (equal area) 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 the northeastern-most p a r t of the map area (J142—>J171) , . 63 32a. Double k ink 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} 64 32b. Clockwise k ink 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} 64 33. D4 f o l d elements f rom 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 rom Domain I (0,10,20% per 1% area contours shown) b. S4 k ink band boundry planes f rom Domain I I (0 & 50% per 1% area contours shown) c. L4 f o l d hinges f rom Domain I (0 & 10% per 1$ area contours shown) d. L4 k ink axes f rom Domain I I (0 & 30% per 1% area contours shown) 65 34. St ress de terminat ion o f D4 episode from deformed S2 f o l i a t i o n s ( f rom Car ter & Rale igh, 1969) 66 35. Contour p l o t s o f po les t o f r a c t u r e s f rom Domains I & I I (contours represent 0,5,10% o f p t s per 1% stereonet area 68 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 top o f the Snowshoe Formation w i t h a t tendant D1 f o l d i n g . b. The upper th ree u n i t s are emplaced atop the lower two x Structural Geology of Part of the Crooked Late Area. Quesnel Highlands. British Colunbia FIGURE PAGE presumably a t a h igher l e v e l o f the c r u s t (no associated de format ion) ; t h r u s t s p l i c i n g may account f o r the p inch ing out o f the Eureka Q u a r t z i t e . c. Ear l y stage o f D2 deformat ion develops p a r a l l e l f o l d s . d. As temperatures and degree of deformat ion increases, p a r a l l e l f o l d i n g g ives way t o s i m i l a r f o l d i n g , and considerable l imb t h i n n i n g o f u n i t s . e. D3 f o l d i n g produces present day p a t t e r n 70 37. Pressure and temperature ranges f o r metamorphism and f a c i e s subd i v i s i on o f the ' P - T ' f i e l d (adapted f rom Turner [1981] p. 420) 75 38a. 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 porphyroblast o f garnet ; 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 ? ) de f ine 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) 80 38b. 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 e ldspar porphyrob las ts ; K-spar i s a l i gned w i t h S2 f o l i a t i o n def ined 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) 80 39. 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 magneti te ve in ing and unusual hornblende c r y s t a l s ; the 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 the more common mica (Plane p o l a r i z e d l i g h t , X12.5,L0C-J104) 82 40. P e l i t i c s c h i s t f rom 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 rup ted by the S2 f o l i a t i o n ; numerous ' h i g h ang le ' b i o t i t e s are common ( top o f photo) and are crossed by S2 rnuscovites ( c r o s s - n i c o l s , X12.5, L0C-RZ10) 84 4 1 . 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 aye rs have l a r g e amount of g raph i te t h a t has been i n j e c t e d up i n t o S2 oleavage planes (probably wh i le u n i t was s t i l l unconsol idated and wet) ( c r o s s - n i c o l s , X12.5, L0C-J7) 85 42a. Ctd-gn-plag-qtz-musc po rphy rob las t i c p h y l l i t e (DIR-005, L0C-J85) . . . 87 42b. Microscopic f a b r i c o f po rphy rob las t i c p h y l l i t e showing p lag and i l m porphyrob las ts 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 x i Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia FIGURE PAGE porphyrob las ts ; S i i n p lag = Se of 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) 87 43a. Porphyrob las t i c p h y l l i t e w i t h p lag , c t d , c h l , and i l m i n con tac t ; c h l occurs i n center o f c t d c r y s t a l ( d a r k ) , the corroded form of which con t ras t s w i t h u n i t s where c t d occurs w i t h no p lag (plane p o l a r i z e d l i g h t , X12.5, L0C-J85) 88 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 porphyrob las ts i s cont inuous 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) 88 44a. Garnet and i l m e n i t e w i t h i n po rphy rob las 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 cont inous 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) 89 44b. S t a u r o l i t e i n po rphy rob las 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 he on ly 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) 89 45. Chl-hnbd-ep-qtz Meta-wacke; maf ic minera ls de f ine the S2 f o l i a t i o n i n these and o ther bas ic u n i t s (p lane p o l a r i z e d l i g h t , X12.5, L0C-RZ4) 93 46. The d i s t r i b u t i o n of maf ic assemblages f o r the A n t l e r Formation; sur faces shown separate assemblages on e i t h e r s ide o f two reac t ions (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 95 47. Pressure temperature p l o t o f e q u i l i b r i a re levan t t o the 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 maf ic composit ion types 97 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) 98 49. Summary o f minera l growth r e l a t i v e t o deformat ion fea tu res composed from diagrams o f i n d i v i d u a l samples and t h i n sec t ions descr ibed i n Appendix A 100 x i i Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia FIGURE PAGE 50. 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 deformat ion 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 the absolute t ime sca le ; metamorphic sca le shows th ree genera l ized grades: b u r i a l , g reensch is t , amphibo l i te 102 x i i i Structural geology of Part of the Crooked Late Area, quesnel Highlands. British ColuitDia TABLES TABLE PAGE I C h a r a c t e r i s t i c Features o f the F ive Phases o f Deformation a t Crooked Lake 38 I I - A D i s t r i b u t i o n o f M inera l Assemblages i n Domain I o f the Crooked Lake Area 76 I I - B D i s t r i b u t i o n o f M inera l Assemblages i n Domain I I o f the Crooked Lake Area 77 x i v Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia PLATES PLATE PAGE 1. The Geology o f Par t o f the Crooked Lake Area .^iacfcrPeGket 2. The S t r u c t u r e o f Par t o f the Crooked Lake Area l . . . ..Book Pooket 3. Two Cross Sect ions o f S t r u c t u r e o f Par t o f the Crooked ^ f ^ M Lake Area Back-Rocket-4. S i x S t r u c t u r a l / S t r a t i g r a p h i c Sect ions o f Par t o f the v n 0>\k^^ Crooked Lake Area . . . Back Pocket. 5. Stereophotos of var ious f e a t u r e s a t Crooked Lake v r a. Chl -hnbd-plag m e t a - d i o r i t e w i t h i n t e r l a y e r e d / i n t e r f o l d e d q t z - c h l s c h i s t ( A n t l e r ) {DIR-325, L0C-RZ3} 179 b. C ross - f rac tu red ch l -hnbd-p lag m e t a - d i o r i t e ; f r a c t u r e s f i l l e d w i t h ep idote , quar tz , and magneti te ( A n t l e r ) {DIR-335, L0C-RZ3} 179 c. Qtz-ch l -hnbd s c h i s t w i t h i n t e r l aye rs o f q tz -p lag-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} 180 d. Red sandstone conta ined 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} 180 e. Typ i ca l contact between A n t l e r hnbd-plag meta- d i o r i t e and Eureka Q u a r t z i t e ; note very open f o l d e d form of contact {DIR-315, LOC-J86} 181 f . Phase one i s o c l i n e o f ch l -hnbd s c h i s t and q tz -p lag-ep meta-wacke ( A n t l e r ) {DIR-350, L0C-RZ6} 182 g. 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 (Snowshoe) {DIR-320, L0C-RZ8} 182 h. Upr igh t phase two medium ' c lockw ise vergence' f o l d i n ch l -p lag-hnbd s c h i s t ; note poss ib le t i g h t f o l d forms invo lved i n upper hinge o f f o l d ( A n t l e r ) {DIR-335, L0C-RZ5} 183 i . Upr igh 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 i n 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 xv 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} 183 j . Upr igh t phase th ree f o l d showing gradual change i n form f rom open t o medium w i t h depth (Eureka Q u a r t z i t e ) {DIR-310,L0C-J98} 184 k. Recumbant t i g h t phase two f o l d re fo lded by u p r i g h t phase th ree medium f o l d (Eureka Q u a r t z i t e ) {DIR-315,L0C-J104> 185 1. Upr igh t steep p lung ing 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 present (near bottom l e f t i n photo) (Crooked Lake P h y l l i t e ) {DIR270, L0C-J33} 185 x v i 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. FULL NAME ASSOCIATED FORMULA OR MEANING Ab a l b i t e (Na[AlSi30e]) Act a c t i n o l i t e (Ca 2(Mg, F e+ 2 ) 5 [ S i 8 0 2 2 ] ( 0 H , F ) 2 ) Anda anda lus i te ( A l 2 S i 0 5 ) Ands andesine (30-50* A n o r t h i t e ) Ank a n k e r i t e (Ca(Mg,Fe + 2 ,Mn)(C03) 2 ) Amph amphibole ac t , t rem, hnbd, parg An a n o r t h i t e (Ca[Al2Si208D Ask aluminium s i l i c a t e s anda, s i l l , ky Bio b i o t i t e (K2(Mg, F e + 2 ) 6 - 4 ( F e+ 3 , A l , T i ) 0 -2 [S i6 -5A l2 -3020 ] (OH, F ) 4 ) Cc c a l c i t e (CaC03) Chl c h l o r i t e ((Mg, A l , F e ) i 2 [ ( S i , A l ) 8 0 2 0 ] ( 0 H ) i 6 ) Ctd c h l o r i t o i d ( ( F e + 2 , M g , Mn)2(Al, Fe + 3 )A l302 [S i04 ]2 (0H)4 ) Clz c l i n o z o i s i t e (Ca2Al-Al 2 03-0H-Si207 'Si04) Cord c o r d i e r i t e (Al3(Mg, F e + 2 ) 2 [ S i s A 1 0 i 8 ] ) Ep ep idote (Ca2Fe+ 3 Al20-0H"Si207"Si04) F e l s i c f e l s i c minera ls fe ldspar or quar tz Gn garnet-almandine ( F e 3 + 2 A l 2 S i 3 0 i 2 ) Graph g raph i te (C) Hnbd hornblende ((Na,K)n-iCa2(Mg, F e + 2 , F e + 3 , Al)5[Si6-7Al2-10221(OH, F)2) I l m i l m e n i t e (FeTi03) Kspar Potassium fe ldspar ( K [ A l S i 3 0 8 ] ) Ky kyan i te (A12S105) Mgt magneti te ( F e + 2 F e + 3 2 0 4 ) Muse muscovite (K2Al4[Si6Al2O20](OH, F)4) O l i g o l i g o c l a s e (10-30* A n o r t h i t e ) 01 o l i v i n e (Mg2Si04-Fe 2Si04) Opaque opaque minera ls i l m e n i t e , magnet i te, p y r i t e Opx orthopyroxene (MgSi03-FeSi03) x v i i Structural Geology of Part of the Crooked Late Area. Quesnel Highlands. British Coluwbia ABBREV. FULL NAME ASSOCIATED FORMULA OR MEANING Para paragoni te (Na2Al4tSi6Al2020](OH, F>4) Parg pargas i te ((Na, K)o- iCa 2 (Mg, F e+ 2 , F e + 3 , A l ) 5 [ S i 6 - 7 A l 2 - l 0 2 2 ] ( O H , F ) 2 ) Plag p lag ioc lase ( N a [ A l S i 3 0 8 ] - C a [ A l 2 S i 2 0 8 ] ) Py p y r i t e (FeS 2 ) Qtz quar tz ( S i 0 2 ) R u t i l e r u t i l e ( T i 0 2 ) Serp serpent ine (Mg 3 [S i205](0H)4) S i l l s i l l i m a n i t e ( A l 2 S i 0 5 ) Sphene sphene ( C a T i [ S i 0 4 ] ( 0 , 0 K F ) ) Staur s t a u r o l i t e ( ( F e + 2 , M g ) 2 ( A l , F e+ 3 ) g 0 6 [ S i 0 4 ] 4 ( 0 , 0 H ) 2 ) Tour tourmal ine (Na(Mg, Fe, Mn, L i , A l ) 3 A l 6 [ S i 6 0 l 8 ] (B03>3(0H, F)4> Trem t r e m o l i t e (Ca2Mg 5 [S i80 2 2](0H,F)2) Vap vapour phase water or carbon d iox ide Zo z o i s i t e (Ca 2 Al"Al203"0H"Si207"Si04) x v i i i Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia ACKNOWLEDGEMENTS I am t r u e l y indebted t o a l l the many people t h a t helped me t o come t o the po in t of complet ing t h i s work. F i r s t of a l l , my apprec ia t i on goes t o my pr imary advisor , J . V. Ross. I f i t were not f o r a l l o f the debates, d iscussions, and valuable i n s i g h t s shared, the path t o proceed on could never have been as c lea r . To my other f a c u l t y adv isors , K.C. McTaggart and R.L. Armstrong, f o r the k ind encouragement and support so f r e e l y g iven. 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 tud ies , t h a t w i l l cont inue t o i n s p i r e my i n t e r e s t f o r many years t o come, and f o r r e i n t r o d u c i n g me t o the fundamental importance of a s t rong mathematical background i n the geo log ica l sciences. 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 reading and he lp ing t o improve my e a r l y d r a f t s . Also, I am g r a t e f u l t o a l l the other f a c u l t y , s t a f f , and e s p e c i a l l y f e l l o w students a t the U n i v e r s i t y of B r i t i s h Columbia t h a t have helped me more than they may r e a l i z e . I would a lso l i k e t o thank A.' J . Hynes, D. Franc is , E. W. Mont j oy , R. Hesse a t McGi l l U n i v e r s i t y who so e x p e r t l y in t roduced me t o the wor ld o f geo log i ca l phenomena. And t o R. B. Campbell, L. C. S t r u i k , a l l the people a t the 6. S. C. and the 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 apprec ia t i on f o r a l l the help I have rece ived. 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 rom N.S.E.R.C. t o J. V. Ross (A-2134) and t h i s i s g r e a t l y apprec ia ted. xix 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. - f rom FLATLAND,, ft ROMANCE OF MANY DIMENSIONS , E. A. Abbott -X X Stiuctuxal Geology of Puxt of the Ciookcd Lake Axca. Quesnel Highlands, British Colunbia INTRODUCTION Loca t ion and Access The Crooked Lake area i s loca ted 60 mi les east o f Wi l l iams Lake i n e a s t - c e n t r a l B r i t i s h Columbia (F igure 1 ) . Th is 25 square k i lometer map-area centers approximately a t l o n g i t u d e 120° 45 ' and l a t i t u d e 52° 15 ' . Hendrix Lake, a Noranda mining town 30 k i l omete rs t o the south, i s the c loses t populated area t o Crooked Lake. F igure 2 i l l u s t r a t e s the exact l o c a t i o n and a rea l ex tent of the area mapped. Crooked Lake can be approached f rom e i t h e r o f two d i r e c t i o n s v i a w e l l maintained logg ing roads t h a t extend as f a r as Horse f l y t o the west and Canim Lake t o the south; paved roads connect these two towns w i t h the Cariboo Highway t o the west (F igures 1 and 2 ) . Physiography and G l a c i a t i o n Crooked Lake l i e s i n the Quesnel Highlands o f the I n t e r i o r Plateau (Hol land 1964). Th is reg ion i s t y p i f i e d by gen t l y r o l l i n g r i dge - tops t h a t range f rom 5500 t o 7000 f e e t i n e l e v a t i o n . G l a c i a l a c t i v i t y has caused the v a l l e y wa l l s t o be considerably steeper than t h e i r corresponding r i d g e - t o p s . Average l o c a l r e l i e f ranges f rom 3000 t o 3500 f e e t . An ax is o f the l a t e s t two g l a c i a l advances occurred i n the Cariboo Mountains t o the nor theast (T ipper 1971). I ce must have f lowed across the Crooked Lake area toward the west and southwest t o reach the I n t e r i o r Plateau (see F igure 3 ) . Most o f the g l a c i a l s t r i a e and depos i ts observed conf i rm t h i s general d i r e c t i o n , though h igh s tanding rock u n i t s and prominent rock s t r u c t u r e were important l o c a l c o n t r o l s on i c e movement d i r e c t i o n . Page 1 52° 30' B i d I ta . V / V 120° 45' 120° | 30* Page 3 Structural Seoloov of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Extensive v a l l e y g l a c i a t i o n i s c h a r a c t e r i s t i c o f more recent t imes. Numerous n o r t h - f a c i n g c i rques , steep wal led *U-shaped' v a l l e y s (see F igure 4 ) , systems of a re tes and horns, and year-round i c e accumulations above 7000' a t t e s t t o t h i s on-going process. F igure 3 D i r e c t i o n o f i c e movement o f Fraser I ce Sheet and l a t e i c e re-advances i n Cen t ra l B r i t i s h Columbia ( f rom Tipper 1971, p. 39) Previous and Current Work Geologic mapping took place as e a r l y as 1889 t o the northwest i n the B a r k e r v i l l e area (Bowman 1889) and 1927 j u s t 30 k i lometers t o the east i n the Page 4 Structural Ecology of Part of the Crooked Lake Urea. Quesnel Highlands. British Colunbia Clearwater Lake area (Marshal 1927), though no systemat ic work i s reoorded f o r the Crooked Lake area u n t i l R.B. Campbel l 's reconnaissance mapping o f the ea r l y 1960's (Campbell 1963 and 1978). Campbell recognised a major s t r u c t u r a l sequence (two ant i fo rms and an i n t e r v e n i n g synform) i n v o l v i n g u n i t s ranging i n age from Precambrian t o Jurass ic . I t was be l ieved t h a t t h i s sequence s t radd led the boundary between two major geologic provinces o f the Canadian C o r d i l l e r a - the Omineca Geant i c l i ne t o the east and the Intermontane B e l t t o the west. F igure 4 - G l a c i a l v a l l e y s t y p i c a l o f the nor theastern slopes o f Eureka Syncl ine K. \1. Campbell (1971) mapped the Crooked Lake area a t a scale o f one inch t o one mi le paying c lose a t t e n t i o n t o major l i t h o l o g i c contacts , pet ro logy, and petrochemistry . He found f o u r major rock u n i t s represented i n the above mentioned s t r u c t u r a l sequence, much i n accord w i t h R.B. Campbell 's e a r l i e r Page 5 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia observat ions. I n a d d i t i o n , he noted t h a t contac ts between the u n i t s were d iscordant (poss ib le low angle t h r u s t i n g ) and t h a t deformat ion and metamorphism occurred dur ing one progress ive episode i n v o l v i n g a l l rock u n i t s . These f i n d i n g s are s i g n i f i c a n t i n t h a t they l i n k the h i s t o r i e s o f two c o n t r a s t i n g geologic provinces a t l e a s t s ince the Mesozoic (Campbell, K.V. 1971). The present author and f o u r o ther masters ' s tudents a t the U n i v e r s i t y o f B r i t i s h Columbia have undertaken t o examine p a r t s o f and beyond the area covered by K.V. Campbell (1971) w i t h c lose a t t e n t i o n being pa id t o d e t a i l e d s t r u c t u r a l f i e l d r e l a t i o n s ( s e e F igure 2 ) . D. Elsby, J . F i l l i p o n e , and J . Montgomery were responsib le f o r the s t r u c t u r a l l y under ly ing Precambrian Kaza Group s t r a t a and upwards i n t o the S l i d e Mountain Group rocks. M. A. Bloodgood has examined the Upper T r i a s s i c t o Jurass ic core rocks o f the Eureka Sync l ine, paying c lose a t t e n t i o n t o vo lcan ic 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 the 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 the 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 the Kaza Group/ S l i d e Mountain Group contact . 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 loca ted i n the southern p o r t i o n o f the Canadian C o r d i l l e r a ; t h i s reg ion has been d i v i d e d i n t o 5 t e c t o n i c b e l t s by Wheeler (1967,1970) t h a t roughly co inc ide w i t h the major landforms o u t l i n e d by Hol land (1964). Three o f these b e l t s (Rocky Mountain, Intermontane, and I n s u l a r ) are composed of only s l i g h t l y metamorphosed supras t ruc tu re and the two t h a t comprise the r e s t (Omineca and Coast P l u t o n i c ) are formed o f a mix ture o f h igh-grade metamorphic t o p l u t o n i c i n f r a s t r u c t u r e and low metamorphic supras t ruc tu re . The rock u n i t s o f the present study occur on the boundary of the Omineca C r y s t a l l i n e B e l t and the Intermontane Zone (see F igure 5 ) . Geologic mapping between the Rocky Mountain and Omineca b e l t s has demonstrated t h a t rock u n i t s a t l e a s t up t o lower Paleozoic are cont inuous across the two zones (Campbell e t a l . 1973). These l a r g e l y m i o g e o c l i n a l / p l a t f o r m a l carbonates 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 basement t h a t cont inues as p a r t o f the c ra ton , i n a s t r i c t sense, only up t o the Rocky Mountain Trench (Mereu e t a l . 1977). Beneath the Omineca rocks Precambrian basement has been i d e n t i f i e d i n the Shushwap T e r r a i n (Duncan 1984), though seismic s tud ies i n d i c a t e t h a t i t s c h a r a c t e r i s t i c s ( e . g . - th ickness , seismic v e l o c i t y ) change markedly f rom east t o west (Berry and Forsy th 1975). Compared t o the r e l a t i v e l y s imple imbr i ca te t h r u s t i n g and open f o l d i n g o f the Rocky Mountain b e l t , the rocks o f the Omineca Gean t i c l i ne have experianced a much more complex de format iona l and metamorphic h i s t o r y . Several broad nor th -sou th t rend ing 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 pa r t o f the b e l t f rom east t o west; these s t r u c t u r e s are genera l l y t h i r d i n a se r i es o f Page 7 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia Figure 5 - Tectonic subd iv i s i ons o f the Canadian C o r d i l l e r a showing present study area (adapted f rom Tectonic Assemblage Hap of the Canadian C o r d i l l e r a , T ipper e t a l . 1981) Page 8 Structural fieology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia f o l d forms, the e a r l i e s t o f whioh i s thought t o oomprise reoumbent nappes w i t h l imb lengths on the order o f severa l k i l omete rs (Ghent e t a l . 1977; Murphy and Journeay 1982; P e l l and Simony 1982). Metamorphism throughout the b e l t ranges from lower greenschis t t o upper amphibo l i te and t o the south i n the b e l t , metamorphic core complexes are unroofed i n the Monashee Complex (Cr i t tenden e t a l . 1980; Brown and Read 1983; O k u l i t c h 1984). The boundary o f the Omineca b e l t w i t h the Quesnel sub- ter rane of the eastern Intermontane zone i s charac te r i zed by s t r u c t u r a l complexi ty s i m i l a r t o t h a t seen i n the Omineca b e l t . Th is i s remarkable s ince f u r t h e r i n t o the Intermontane zone simple t h r u s t f a u l t i n g and gen t le 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 Tipper 1970; Travers 1978). Thrust f a u l t i n g , t e c t o n i c i m b r i c a t i o n , and mylon i te development are very common along t h i s zone (Campbell 1971; Montgomery 1978; Ross 1981; Brown and Read 1983). Perhaps the most s t r i k i n g f e a t u r e o f the Omineca/Quesnel boundary i s a ub iqu i tous b e l t o f u l t ramaf i o s , amphibo l i tes , basa l t s , and sediments o f s t rong oceanic a f f i n i t y t h a t some have suggested i s the remains o f a l a t e Paleozoic ocean c r u s t l o c a l l y obducted on t o the miogeoc l ina l rocks t o the east (Montgomery 1978; Rees 1981). Th is b e l t can be found c o n s i s t e n t l y f rom nor th t o south separat ing the rock types o f the two prov inces (see F igure 6 ) . The Quesnel rocks c o n s i s t o f v o l c a n i c l a s t i c s , vo lcan ics , a r g i l l i t e s , and carbonates, poss ib ly fo rming a Late T r i a s s i c subduct ion arc complex formed on upper Paleozoic rocks (Monger 1977; Travers 1978). Examination of f auna l d i s t r i b u t i o n s and paleomagnetic determinat ions i n rocks o f Permian t o Jurass ic age suggest t ransour ren t displacements r e l a t i v e t o s i m i l a r rock types i n North America on the order o f one t o two thousand k i l omete rs (Monger e t a l . 1982). This would Page 9 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 the Quesnel - North America suture zone (Figure 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 not 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 the Nor th American s i t u a t i o n t h a t developed i n the e a r l y Mesozoic. Cer ta in rock types occu r r i ng w i t h i n or across the two b e l t s prov ide important evidence t h a t they have shared a common h i s t o r y a t l e a s t s ince the l a t e Mesozoic. The most notab le example o f t h i s i s i n the Bowser Basin t o the northwest i n the Intermontane b e l t ; Lower Cretaceous depos i ts con ta in metamorphic d e t r i t u s t h a t could on ly have been der ived from Omineca b e l t rocks t o the east (Eisbacher 1974; Monger e t a l . 1978). I n a d d i t i o n , a per iod o f i n t r u s i v e a c t i v i t y l i n k s the h i s t o r i e s o f the two b e l t s ; these are the "100 m. y . " i n t r u s i v e s o f Campbell and Tipper (1970). The most recent h i s t o r y has seen extens ive Eocene vo lcan ic and v o l c a n i c l a s t i c a c t i v i t y f o l l o w e d by Miocene t o Pl iocene p la teau basa l t s . Extensive Quaternary g l a c i a l depos i ts f rom a t l e a s t th ree d i s t i n c t events cover l a rge pa r t s o f the reg ion (T ipper , 1971). Local 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 (1963) and examined by K.V. Campbell (1971) are, i n s t r a t i g r a p h i c / s t r u c t u r a l succession, the Pro terozo ic Kaza group, the Pennsylvanian t o Permian A n t l e r Formation, a micaceous q u a r t z i t e and grey t o b lack p h y l l i t e s o f probable Upper T r i a s s i c t o Lower Jurass ic age, and a Lower Jurass ic v o l c a n i c / v o l c a n i c l a s t i c assemblage. Th is same sequence of u n i t s , w i t h minor v a r i a t i o n s , cont inues t o the northwest and southeast (see F igure 6) and has been descr ibed and dated by numerous workers (Suther land Brown 1957 & 1963; Campbell e t a l . 1973; S t r u i k 1980; Rees 1981; Uglow 1921; Campbell and Tipper 1971; Orchard & S t r u i k 1985). Page 11 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia A l l rock u n i t s have been invo lved i n l a t e stage, northwest t r end ing f o l d s - Perseus A n t i c l i n e , Eureka Sync l ine, Boss Mountain A n t i c l i n e (Campbell, K.V. 1971). Bar rov ian metamorphism poss ib ly ooinc ided w i t h the development o f these s t r u c t u r e s , though e a r l i e r events could a lso be present (Campbell, K.V. 1971). North t o nor theast 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 e f f e c t i n g the u n i t s a t Crooked Lake inc lude nor theast t r e n d i n g h igh angle f a u l t s . T e r t i a r y o l i v i n e basa l t , and t h i c k (30-50 m) g l a c i a l deposi ts i n the v a l l e y bottoms and low l y i n g reg ions. Page 12 Structural Geology of Part of the Crooked Lake area, Quesnel Highlands, British coluwbia STRATIGRAPHY I n t r o d u c t i o n I n the Crooked Lake area the present author has f u r t h e r separated the 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 d i s t i n c t u n i t s on the bas is o f co lour , t e x t u r e s , and mineralogy. The a d d i t i o n a l u n i t , a micaceous q u a r t z i t e , was o r i g i n a l l y inc luded w i t h the 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 the Eureka Quar t z i t e and the Crooked Lake P h y l l i t e , r e s p e c t i v e l y . I n low l y i n g regions, where g l a c i a l cover i s s i g n i f i c a n t , contac ts between the u n i t s were never c l e a r l y observed (see F igure 7b; note: a l l subsequent photographs i n the t e x t w i l l i n d i c a t e the d i r e c t i o n a photograph was taken, as an azimuth {DIR-045} and, where app l i cab le , i t s l o c a t i o n as a s t a t i o n number {L0C-J11}) . As the geolog ic map (P la te 1) shows, contacts across the southwestern p o r t i o n o f the area were i n t e r p o l a t e d f rom outcrops o f the var ious l i t h o l o g i e s . Although, c o n t r o l f o r the placement o f these contac ts i s poor i n places, i t i s be l ieved they have the best poss ib le c o n f i g u r a t i o n f o r the d i s t r i b u t i o n o f the a v a i l a b l e g iven data. The steep slopes nor theast o f Crooked Lake, on the other hand, o f f e red an e x c e l l e n t oppor tun i t y t o observed the u n i t s ' contacts exposed f o r considerable d is tances (see F igure 7a and P l a t e 1 ) . The two lowest contac ts 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 laces ( w i t h i n a zone of a few meters t h i c k n e s s ) , though otherwise t o be sharp ly p lanar . The uppermost contact (F igure 7c) shows obvious i n t e r f i n g e r i n g , as w e l l , though r e l a t i o n s are not as c l e a r cu t as the lower contac ts . The middle contac t between the Eureka Q u a r t z i t e and the Crooked Lake Page 13 Figure 7 - Contacts of the Crooked Lake rock u n i t s Takla contact zone i s assumed from K.V. Campbell (1971) {DIR-045} Figure 7c - Happed contac ts between Crooked Lake P h y l l i t e and Takla i n the nor theastern contac t zone; note poss ib le p h y l l i t e i n f o l d a t top r i g h t re F igure 16d {DIR-318} Page 15 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia P h y l l i t e was not seen exposed; t a l u s f rom the r a p i d l y eroding p h y l l i t e b u i l d s up above the 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 sur face. P la te 1 does not show i n t e r n a l subd i v i s i on f o r the Crooked Lake u n i t s ; f i n e scale o r i g i n a l g rada t ion and i n t e r f i n g e r i n g (most l i k e l y due t o d u c t i l e response of subuni ts and complex f o l d i n g ) occurs on a scale t h a t i s impossible t o show on the map. I n order t o present the i n t e r n a l subd iv i s ions o f these u n i t s s t r u c t u r a l / s t r a t i g r a p h i c columns were const ruc ted once the l a t e r (post D2; see STRUCTURE, below) l a r g e - s c a l e s t r u c t u r a l f ea tu res were understood; these diagrams (see P l a t e 1 and P l a t e 4) are o r i e n t e d , as much as poss ib le , i n the d i r e c t i o n o f o r i g i n a l l i t h o l o g i c v a r i a t i o n and do represent a s t r a t i g r a p h i c succession w i t h respect t o the major l i t h o l o g i c u n i t s . I t must be s t ressed, however, t h a t s ince the e a r l i e r s t r u c t u r a l f ea tu res could not be removed, these columns merely o u t l i n e the th icknesses o f e x i s t i n g subuni ts and t h e i r e x i s t i n g r e l a t i v e placement, and should not be i n t e r p r e t e d as suggest ing o r i g i n a l th icknesses ( f o r any u n i t or subun i t ) nor probable o r i g i n a l s t r a t i g r a p h i c successions f o r i n t e r n a l subun i ts o f the major l i t h o l o g i e s . Appendix A conta ins rock d e s c r i p t i o n s referenced t o segments o f the s t r u c t u r a l / s t r a t i g r a p h i c columns (P la te 4) and t o s t a t i o n l o c a t i o n s shown on the geologic map (P la te 1 ) . Below i s an account o f ages, d i s t r i b u t i o n s , th icknesses, sub-un i t s , o r i g i n , and contact r e l a t i o n s h i p s o f the f i v e u n i t s a t Crooked Lake. The geologic map (P la te 1) , the s t r u c t u r a l / s t r a t i g r a p h i c columns (P la te 4 ) , and Appendix A should be r e f e r r e d t o du r ing the course o f t h i s d iscuss ion . Kaza Group - Snowshoe Formation This u n i t i s be l ieved the o ldes t exposed i n the map-area. An age of Late Pro te rozo ic stems f rom R.B. Campbell e t a l . (1973) who have c o r r e l a t e d i t w i t h the Page 16 Structural Geology of Part of the Crooked Lake area. Quesnel Highlands. British Coluwbia middle M ie t te Group of the same age i n the Rooky Mountain b e l t on the bas is o f gross l i t h o l o g y . The type area f o r the Kaza i s Bowron Lakes P r o v i n c i a l Park (Suther land Brown 1963); t h e re , the 12,000 f o o t t h i c k u n i t cons is ts o f unsorted, f e l d s p a t h i c g r i t i n t e r l a y e r e d w i t h s c h i s t and greenish-grey t o dark grey p h y l l i t e . F igure 8 - 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 o f the Snowshoe Formation i n the Crooked Lake area {DIR-350,L0C-RZ10} I n the map-area the Kaza occurs i n the cores o f a l l a n t i f o r m a l s t r u c t u r e s and under l ies the synforms; outcrops are r e s t r i c t e d t o the southernmost p a r t o f the area. K.V. Campbell (1971) has est imated the exposed Page 17 structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Colunbia th ickness o f the Kaza i n the Crooked Lake area as being between 15,000 and 30,000 f e e t ; s ince very l i t t l e s t r a t i g r a p h i c or s t r u c t u r a l d e t a i l i s known about the u n i t t o date i t i s d i f f i c u l t t o a s c e r t a i n the amount o f t e c t o n i c t h i cken ing t h i s f i g u r e might inc lude ( i t i s , though, expected t o be a minimum o f 100% because composi t ional l a y e r i n g i s a t ransposed f o l i a t i o n , see STRUCTURE below). Snowshoe rocks c o n s i s t predominately o f i n t e r l a y e r e d p lag-mica-q tz s c h i s t and mica q u a r t z i t e w i t h subord inate hor izons o f mica-p lag-q tz s c h i s t and q tz -p lag-mica s c h i s t (note: m inera l names used through the t e x t are g iven i n a • l eas t - t o -mos t f o r m a t ' , i . e . , q tz -p lag-mioa s c h i s t i s a rock w i t h q tz i p lag _ mica) . Th is u n i t i s medium t o coarse gra ined w i t h l a y e r i n g between the g rada t iona l l i t h o l o g i e s ranging f rom very f i n e ( m i l l i m e t e r s ) t o very coarse (meters) . F igure 8 shows a t y p i c a l exposure o f t h i s rock type. The on ly outs tanding t e x t u r a l f ea tu res t h i s u n i t d i s p l a y s l o c a l l y are p e r t h i t e porphyroblasts and a f i n e banding composed o f 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 ( these are best seen i n the southwestern p o r t i o n o f t he map area; r e f e r t o F igure 38a). Minor l i t h o l o g i e s inc lude p e l i t i c marbles, qtz-ep-hnbd s c h i s t , c h l - r i c h s c h i s t , and dark p h y l l i t e (o r very f i n e gra ined s c h i s t ) . Coarse grained marbles are found r e s t r i c t e d t o two 30 meter t h i c k bands o f mica s c h i s t and marble w i t h i n the main s c h i s t ; muscovite de f ines a weak f o l i a t i o n and quar tz occurs as rounded g ra ins . These marbles show banding (composed of very f i n e c a l c i t e and minor muscovite; r e f e r t o F igure 48) s i m i l a r t o t h a t seen i n the s c h i s t . S t r u c t u r a l l y below the marble band on the nor theas te rn s ide o f the lake, a 40 meter th ickness o f qtz-ep-hnbd s c h i s t crops ou t ; t h i s u n i t i s medium t o coarse grained w i t h w e l l developed composi t ional l a y e r i n g o f epidote and quartz /hornblende. C h l - r i c h s c h i s t s hor izons are d i s t i n c t i v e because o f t h e i r co lour d i f f e r e n c e , but Page 18 Structural ecology of Part of the crooked Lake Area, Quesnel Highlands. British colunbia Figure 9 - Snowshoe/Antler contact F igure 9a - Sharply def ined contact between Snowshoe Formation (below) and A n t l e r Formation (above) {DIR-03aL0C-J112} F igure 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 the contact between the 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 igure 12 {DIR-020,L0C-J114} Page 19 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 d i f f e r f rom the main s o h i s t package ( i . e . oh l i s the main or only mica, but f e l s i c s predominate). Rare dark p h y l l i t e s (very f i n e grained s c h i s t s ) were found i n the southwestern map area and are be l ieved t o represent a t r u e Snowshoe s u b - l i t h o l o g y as opposed t o being a s t r u c t u r a l i n f o l d o f the o v e r l y i n g , younger Crooked Lake P h y l l i t e ( the only l i k e l y source i n the area f o r t h i s l i t h o l o g y ) . Kaza rocks probably o r i g i n a t e d as a sequence o f immature t o submature quar tz a r e n i t e s , quar tz arkoses, and quar tz wackes deposi ted i n a nearshore f l u v i a l environment. The minor rook types may represent o r g a n i c - r e l a t e d carbonate accumulations ( the marble and poss ib ly the qtz-ep-hnbd s c h i s t ) and/or l o c a l i z e d vo loan ic a o t i v i t y ( t he qtz-ep-hnbd s c h i s t ) . The lower contact o f the Kaza Group i s not seen anywhere i n the Crooked Lake area. Fur ther t o the east , though, the c o r r e l a t i v e Horse th ie f Creek Group l i e s above the pre-Hadrynian Malton Gneiss, (Ghent e t a l . 1977), which may represent Archean basement t o both these u n i t s . The upper Kaza contac t i s exposed throughout h a l f o f the map-area and c l e a r l y i n f e r r e d f o r the r e s t . Th is sur faoe i s sharp against the o v e r l y i n g A n t l e r rocks (F igure 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 invo lves the contact (F igure 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 below); t h i s causes an apparent r e p e t i t i o n o f t he d i f f e r e n t u n i t s i n the v i c i n i t y o f the contact . Th is geometry suggests t h a t the ' t e c t o n i c s l i c e s o f A n t l e r - l i k e l i t h o l o g i e s w i t h i n the Kaza* repor ted by K. V. Campbell (1971) are man i fes ta t ions o f t h i s same t i g h t f o l d i n g ( e . g . , r o o t l e s s f o l d hinges o f A n t l e r appearing as l enso id bodies w i t h i n the Kaza). Even though s t r u c t u r e s t o e i t h e r s ide o f t h i s contac 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 the map area, the degree t o which the adjaoent rooks have been fo lded and poss ib ly my lon i t i zed i n d i c a t e s t h a t some amount o f separa t ion must be associated w i t h t h i s sur face; numerous researchers (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 the present author, be l ieve t h a t t h i s u n i t i s i n f a u l t contact w i t h the 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 de f ined by Suther land Brown (1957 and 1963) when he modi f ied fo rmat ions o f the S l i d e Mountain Group proposed by Johnson and Uglow (1926). Recent work i n the type area no r th o f B a r k e r v i l l e and the Cariboo River by S t r u i k (1981) has y i e l d e d Pennsylvanian and Permian ages f o r conodonts i n cher t o f the A n t l e r Formation (Orchard and S t r u i k 1985). There, the major rock types inc lude p i l l o w basa l t , d i o r i t e , minor gabbro and u l t r a m a f i c rocks, a r g i l l a c e o u s cher t , s l a t e , and greywacke. F igure 6 shows the d i s t r i b u t i o n of the S l i de Mountain Group rocks throughout 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 the map-area. A n t l e r rocks everywhere separate the Kaza Group f rom the o v e r l y i n g Eureka Quar t z i t e and Crooked Lake P h y l l i t e . I n the western pa r t o f the map-area a maximum present th ickness o f 1200 meters i s est imated f o r the hinge reg ion of the an t i fo rm/syn form 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 the western f l a n k o f the Boss Mountain A n t i c l i n e s h a l l be hencefor th c a l l e d the Basset /Stark s t r u c t u r a l p a i r ) ; t h i n n i n g occurs w i t h i n the u n i t as i t arches over the Boss Mountain A n t i c l i n e b r i n g i n g i t t o a minimum th ickness o f under 300 meters on the nor theast s ide o f Crooked Lake (see F igure 10). Mapping by R.B. Campbell (1978) and K.V. Campbell (1971) suggests t h a t such t h i c k e n i n g and t h i n n i n g i s a lso c h a r a c t e r i s t i c o f t h i s u n i t ou ts ide the map-area. Page 21 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British 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 (mg t ) - ch l -p lag -ep Meta-wacke and Massive Q u a r t z i t e Igneous D e r i v a t i v e s CEHP Heta-diorite f oeta-vacke Rgt-CM-Qtz veins Massive and Cross - f rac tu red ch l -ep-hnbd-p lag Me ta -D io 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 " • ' t t t t f t t t t t t t t • f / t s t t t t t t * * / / / / / / • / ' t t f f t t 'ttt * Ep-p lag-ch l -hnbd s c h i s t t o chl -hnbd s c h i s t F igure 11 Summary o f the 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 the Crooked Lake area i s a d iverse c o l l e c t i o n o f g rada t iona l l i t h o l o g i e s . F igure 11 p i c t o r i a l l y o u t l i n e s the main s u b - l i t h o l o g i e s encountered across the map area; t h ree common t e x t u r a l v a r i a n t s - the c l a s t i c appearing *meta-wackes', the igneous appearing " m e t a - d i o r i t e s * , and the metamorphic p h y l l i t e s and s c h i s t s , - are shown. The meta-wackes (P la tes 6c, f ) are charac te r ized by an abundance o f quar tz , f e ldspar , and ep idote ; they range from very f i n e t o medium gra ined and are genera l l y l i g h t i n co lour (see Figure 45) . They are i n t e r l a y e r e d on a f i n e t o medium scale w i t h p h y l l i t e s / s c h i s t s and i t i s not unusual t o f i n d them as lenso id bodies ' f l o a t i n g ' i n a p h y l l i t i c / s c h i s t o s e m a t r i x ( F igure 11 & P l a t e 6 c ) . This l i t h o l o g y i s most abundant i n the southwestern map area. The m e t a - d i o r i t e s (P la tes 6a, b, d) con ta in 30-60% evenly d i s t r i b u t e d dark maf ic minera ls ( c h l o r i t e , hornblende) w i t h p lag ioc lase , ep idote , and quar tz ; the g r a i n s i ze i s medium t o coarse and the t e x t u r e i s best descr ibed as spot ted ( l i g h t f e l s i c ma t r i x w i t h green maf ic aggregate spots d i s t r i b u t e d evenly th roughout ) . Th is u n i t i s found e i t h e r 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 i s t or as massive u n i t s w i t h numerous c r o s s - c u t t i n g f r a c t u r e s and mgt-ep-qtz ve in ing (F igure 11 & P la tes 6a, b ) . P h y l l i t e and s c h i s t toge ther c o n s t i t u t e the dominant l i t h o l o g y i n the A n t l e r , though they seem t o be l e s s r e p r e s e n t a t i v e i n the southwestern map area. These ' s c h i s t s ' are f i n e t o medium gra ined q tz -ep-p lag -ch l -hnbd aggregates w i t h very w e l l developed f o l i a t i o n and occas iona l l y f i n e l a y e r i n g . A n t l e r rocks inc lude as minor l i t h o l o g i e s b l u i s h q u a r t z i t e , calcareous s c h i s t , and se rpen t in i zed p e r i d o t i t e . The q u a r t z i t e occurs i n assoc ia t ion w i t h the meta-wacke l i t h o l o g y as t h i n lenses (< 1 decimeter) and o f t e n i s so f i n e grained as t o appear ' c h e r t y ' ( t h i s may represent 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 grained sediment or , oonversely, 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 u n i t 6 > . Medium gra ined calcareous s c h i s t occurs as a f a i r l y major p a r t o f the A n t l e r (10-20%) f rom j u s t west o f Stark Lake, eastward and no r th t o Crooked Lake; the c a l c i t e i n the u n i t de f ines a metamorphic l a y e r i n g and ve in ing (probably f rom d i f f e r e n t events) and does not occur w i t h hornblende. Much o f t h i s s c h i s t i s a lso associated w i t h the meta-wacke l i t h o l o g y . One pod o f se rpen t in i zed p e r i d o t i t e was found i n the southernmost p a r t o f the southwestern map area; i t i s coarse grained and h i g h l y f r a c t u r e d (two se ts o f f r a c t u r e s con ta in serpent ine and c a l c i t e r e s p e c t i v e l y ) . I t i s unknown what r e l a t i o n s h i p t h i s u n i t has t o the surrounding u n i t s as no con tac ts were seen. From t h i s d iscuss ion 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 the re e x i s t s a genera l ized d i s t r i b u t i o n o f u n i t s w i t h i n the A n t l e r across the map area. P la te 4, S e c t i o n s l , 2 ,4 and 5 demonstrate t h i s change. I n the southwest map area a l l o f the major u n i t s are represented i n near ly equal p ropor t ions and two o f the minor u n i t s , q u a r t z i t e and se rpen t in i zed p e r i d o t i t e , occur l o c a l l y . To the no r th , the calcareous l i t h o l o g y becomes more abundant, in te rmixed 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 ve in ing occurs and minor s u l f i d e s are present (most ly p y r i t e ) . The A n t l e r encountered i n t he nor theastern 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 smal ler p r o p o r t i o n o f meta-wacke. This l i t h o l o g i c change w i t h i n the body o f the A n t l e r f rom southwest t o nor theast may stem from an o r i g i n a l l i t h o l o g i o d i s t r i b u t i o n ( i . e . , a western sediment f a c i e s versus an eastern igneous f a c i e s ) or f rom e a r l y phase t i g h t f o l d i n g ( i . e . , causing l o c a l i z e d r e p e t i t i o n or s tack ing o f meta-wacke u n i t s ) . Page 25 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Minor fea tu res w i t h i n the A n t l e r rocks suggest t h a t both o f these f a c t o r s have played a pa r t i n the product ion o f t h i s present d i s t r i b u t i o n . F igure 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 lag -ch l -hnbd s c h i s t (dark u n i t ) 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 of the amount o f i n t e r n a l deformat ion undergone by t h i s u n i t and lack of p reserva t ion o f good pr imary fea tu res , the nature o f the o r i g i n a l c o n f i g u r a t i o n o f u n i t s i s specu la t i ve a t best . I t i s c lea r , though, t h a t t h i s u n i t o r i g i n a t e d as a vo lcan igen ic sequence o f in te rmedia te t o basic composit ion. The occurrence o f u l t r a m a f i c s and very f i n e gra ined sedimentary in terbeds would suggest an oceanic s e t t i n g f o r t h i s sequence, and perhaps, as Montgomery, (1978) has suggested, an o p h i o l i t e assoc ia t i on . The upper contact o f the A n t l e r rocks i s w e l l exposed on the nor theast s ide o f the f i e l d area (P la te 6d) , but i s i n f e r r e d t o the southwest. Where exposed, t h i s sur face shows the type o f u n i t r e p e t i t i o n seen i n t he lower contact (F igure Page 26 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia 12), a l though f a r more pronounoed . The o r i g i n o f t h i s sur face i s probably s i m i l a r t o t h a t o f the A n t l e r ' s lower oontact ( i . e . a t h r u s t f a u l t ) ; the r e l a t i o n s h i p s between adjacent s t r u c t u r a l f ea tu res and the two sur faces are e s s e n t i a l l y equ iva len t , and i n d i c a t e t h a t they have shared a common h i s t o r y s ince before the D2 deformat ion. Eureka Q u a r t z i t e Th is u n i t was o r i g i n a l l y inc luded w i t h the p h y l l i t e by K.V. Campbell (1971), but here i s separated on the bas is o f general d i s s i m i l a r i t y i n terms of composit ion and t e x t u r e . No i n d i c a t i o n o f the age o f t h i s u n i t i s a v a i l a b l e f rom the Crooked Lake area, though i n f o r m a t i o n concerning u n i t s o f s i m i l a r l i t h o l o g y and s t r u c t u r a l p o s i t i o n t o t he n o r t h suggests t h i s q u a r t z i t e may be Lower Jurass ic and thus younger than the o v e r l y i n g Crooked Lake P h y l l i t e ( S t r u i k 1981). The present author doubts t h a t t h i s i s so, i f indeed i t i s the same u n i t ; i t i s more l i k e l y , cons ider ing t h a t i t occurs below the Crooked Lake P h y l l i t e , t h a t i t i s the o lder o f the two. The q u a r t z i t e occurs as a wedge between the p h y l l i t e and the A n t l e r cropping out along the nor theast s ide o f Crooked Lake (see P l a t e 4, Sect ions4 & 6 ) ; K.V. Campbell (1971) has mapped the u n i t around the nose and along the nor theast l imb o f Eureka Sync l ine. I t s th i ckness w i t h i n the map area i s l e s s than 20 meters, though according t o K.V. Campbell (1971), i t increases i n th ickness toward the east. I n outcrop the u n i t i s f i n e t o medium layered , f i n e t o medium gra ined, micaceous q u a r t z i t e and g r a p h i t i c micaceous q u a r t z i t e (see Figure 13). Occasional ly , hor izons con ta in hornblende, though t h i s i s be l ieved the r e s u l t of Page 27 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia degradation o f garnet i n the presence of b i o t i t e , magnet i te, and quar tz . These rocks poss ib ly formed i n a d i s t a l f l u v i a l or near shore beach environment. F igure 13 - Micaceous q u a r t z i t e w i t h pervasive p l a t y t e x t u r e ; boudined and fo lded quar tz ve in ing i s a common f e a t u r e i n t h i s u n i t {DIR-062, L0C-J94} Only the lower contac t o f the q u a r t z i t e was seen exposed (see P la te 6d) . The upper contact i s bur ied beneath abundant t a l u s formed from the h igh l y recessive ove r l y i ng p h y l l i t e . Crooked Lake P h y l l i t e This u n i t occurs as a roughly cont inuous b e l t on the west s ide o f the S l i d e Mountain Group shown i n F igure 6 (R. B. Campbell e t a l . 1973). R.B. Campbell and Tipper (1971) found belemnites o f poss ib le 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 the Bonaparte map area t o the south, a l though, as Campbell, R. B. e t a l . (1973) po in t out, none of these f i n d s i s conc lus ive due t o ' l a c k o f c r i t i c a l exposures' . The present author found severa l l i t h o l o g i c sub -un i t s t h a t might have poss ib ly Page 28 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia y ie lded r e s u l t s i n terms o f conodont d a t i n g ; un fo r tuna te l y the r e s u l t s f rom a sample sent t o the Geolog ica l Survey o f Canada were inconc lus ive (R.B. Campbell, personal communication, 1982). F igure 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 rong f o l i a t i o n and d iscont inuous, 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} P h y l l i t e s orop out over a good pa r t o f the western p o r t i o n o f the map-area and cap the f i r s t r i dge nor theast o f Crooked Lake (Ta lbot Ridge of K. V. Campbell (1971)) . A minimum o f 1800 meters o f present th ickness o f p h y l l i t e occurs between the A n t l e r rocks and the o v e r l y i n g v o l c a n i c / v o l c a n i c l a s t i c s t o the nor theast o f Crooked Lake. 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 sur face cannot be t raced cont inuous ly across the map-area, though i t i s be l ieved t o be i n excess o f the above-mentioned minimum f i g u r e and poss ib ly i n excess of the maximum c i t e d by K.V. Campbell (1971) (around 2600 meters) . 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 High ly transposed p h y l l i t e w i t h p h y l l i t i c s i l t s t o n e 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 s i l t s t o n e w i t h p h y l l i t e and occas iona 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, po rphy rob las t i c p h y l l i t e , syner i s i s -c racked meta -mic r i te , sandy l imestone Figure 15 - Summary o f the 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 Lake p h y l l i t e i s composed almost e n t i r e l y o f f i n e l y layered, micaceous p h y l l i t i c s i l t s t o n e and g r a p h i t i c p h y l l i t e ( r e f e r t o P la te 4, Sect ions 2 , 3 , 4 , & 6 ) . I n most exposures, muscovite, quar tz , and g raph i te are the major c o n s t i t u e n t s ; c h l o r i t e , i l m e n i t e , and tourmal ine are minor but near ly always present. The p h y l l i t i c s i l t s t o n e usua l l y forms d iscont inuous l a y e r i n g and/or * f o l d e d ' l enso id shapes i n a m a t r i x o f p h y l l i t e (see F igure 14) ; when p h y l l i t i c s i l t s t o n e predominates the u n i t takes on a more regu la r layered (o r bedded) appearance. F igure 15 demonstrates the ohange i n charaoter t y p i c a l o f the bulk t h i s 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 . Thin q u a r t z i t e and f e l s i c s c h i s t 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 severa l deformat ion episodes has been extreme (most l i k e l y because of i t s un i fo rm character and f i n e gra ined t e x t u r e ) ; any o r i g i n a l l a y e r i n g t h a t occurred i n the u n i t has been transposed and now, i n most l o c a l i t i e s , de f ines a h i g h l y d iscont inuous l a y e r i n g s u b - p a r a l l e l t o a s t rong f o l i a t i o n (see F igure 14). As a consequence, coarser, more competent hor izons occur r ing i n the p h y l l i t e package no longer e x i s t as c l e a r l y mappable u n i t s , though i t i s poss ib le , i n a very general sense, t o i d e n t i f y packages of c o n t r a s t i n g l i t h o l o g y w i t h i n the p h y l l i t e . These packages i n t he p h y l l i t e roughly p a r a l l e l the major contacts . There are th ree d i f f e r e n t types t h a t occur - s i l t s tone /sands tone , a porphyrob las t i c l i t h o l o g y , and a l imes tone /vo lcan igen ic l i t h o l o g y . The s i l t s t o n e / sandstone package cons i s t s o f l i g h t co loured s i l t s t o n e and f i n e sandstone of quar tz a r e n i t e t o arkose composi t ion; i t i s f i n e t o medium layered and conta ins c h l - a n k e r i t e s c h i s t and nodules o f syneres is cracked m i c r i t i c l imestone (Figure 15). Th is l i t h o l o g y i s common on the nor theas tern f l a n k o f the major h i l l i n the Page 31 Structural Geology of Part of the Crooked Lake Area, quesnel Highlands. British Coluwbia western map area and along the top and nor theast s ide o f Ta lbot Ridge. The porphyrob las t i c l i t h o l o g y i s t y p i f i e d by s t rong po rphy rob las t i c t e x t u r e s (see F igures 42-44) ; porphyrob las ts inc lude almandine garnet , c h l o r i t o i d , s t a u r o l i t e , p lag ioc lase , and i l m e n i t e ; very f i n e t o f i n e muscovite, quar tz , g raph i te , and c h l o r i t e form the m a t r i x f o r these coarse t o very coarse porphyrob lasts . Th is package crops out along much of the steeper southwest slopes o f Ta lbot Ridge; i t s abundance increases s i g n i f i c a n t l y toward the southeast. One i s o l a t e d occurrence o f t h i s u n i t e x i s t s i n t he western map area on the nor thern slope o f t he major h i l l ( S t a t i o n J47). The l imes tone/vo loan igen ic package was examined i n the nor theastern map area below Alex and Reggie Lakes and a lso t o the northwest o f the cu r ren t map area, both i n apparent assoc ia t i on w i t h the upper Crooked Lake P h y l l i t e / T a k l a contac t zone. Limy sediments (<30% c a l c i t e ) are in te rspersed w i t h 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 t h a t look more green than grey. These u n i t s con ta in very f i n e gra ined ank-musc-chl -py-ab-ep-qtz-cc and b i o - e p - f e l s i o - a c t , assemblages r e s p e c t i v e l y . I n one sample o f the l a t t e r l i t h o l o g y , 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 . The rhythmic nature o f t h i s p h y l l i t e , the abundance o f g raph i te (30% or more), and a f i n e g r a i n s i ze suggest perhaps a d i s t a l , r e s t r i c t e d t o anaerobic(abundance o f p y r i t e ) submarine fan environment as an o r i g i n o f t h i s u n i t . I f i t i s poss ib le t o r e l a t e t h i s sequence t o t he o v e r l y i n g Takla Group rocks then t h i s fan may have formed adjacent t o a quiescent i s l a n d arc occas iona l ly r e c e i v i n g calcareous m a t e r i a l and vo lcan ic d e t r i t u s f rom nearby regions and even tua l l y becoming emergent as an a c t i v e p a r t o f the arc i t s e l f . The lower contact o f the p h y l l i t e was never seen exposed. To the 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 the nor theast the Eureka Q u a r t z i t e wedges i n Page 32 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia between the two t o u n d e r l i e t he p h y l l i t e . The upper oonteot o f the p h y l l i t e oocurs i n two d i s t i n c t l o c a l i t i e s . To the west i t i s l a r g e l y covered i n a zone approximately 300 meters between outcrops 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 igure 7b) and i s associated w i t h t i g h t f o l d i n g and s t rong mylon i te development i n the Takla rocks ; t o the east the contact zone cons is t s o f a s e r i e s o f i n t e r d i g i t a t i o n s o f t he two u n i t s (see P la te 3 and F igure 7c) and i s associated w i t h a l a rge amount o f t i g h t f o l d i n g , again i n a zone about 300 meters t h i c k . This contact probably o r i g i n a t e d as a pr imary sur face o f depos i t i on , w i t h l a t e r , l o c a l i z e d displacement occu r r i ng along i t . Takla Group This u n i t i s g iven the fo rma l name o f Takla Group rocks according t o Tipper e t a l . (1979). I t i s an ex tens ive u n i t i n the Quesnel T e r r a i n t o t he west and south where i t occurs near Upper T r i a s s i c vo lcan ics and sediments o f the N ico la Group. The Takla Group i s t y p i f i e d by b a s a l t i c t o a n d e s i t i c vo lcan ics and v o l c a n i c l a s t i c s w i t h minor shale, sandstone, conglomerate, and l imestone. Takla Group rocks occur a t the e x t r e m i t i e s o f the f i e l d area t o the southwest and nor theast . K.V. Campbell (1971) shows rocks o f t h i s group cropping out i n the center o f the Eureka Sync l ine ; t o the n o r t h p h y l l i t e s s i m i l a r t o the under ly ing u n i t o v e r l i e the Takla rocks. Approximately 2300 meters o f Takla and p h y l l i t e i s contained i n the Eureka Sync l ine above the lower p h y l l i t e u n i t . I n the map area u n i t s observed inc lude c h l o r i t e p h y l l i t e s , mat r ix -suppor ted h o r n b l e n d e - d i o r i t e brecc ias , c las t - suppor ted d i o r i t e conglomerates, immature f e l d s p a t h i c sandstones, and aug i te porphyry f lows (see F igures 19a-d). Wi th in t he Takla the general c o n f i g u r a t i o n i s one of coarsening upwards; f rom west t o east f i n e r s i l t s grade i n t o coarser Page 33 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia Figure 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 the Takla Group rocks Figure 16a - F o l i a t e d ch l -hnbd-p lag m e t a - d i o r i t e w i t h lenso id /sphero ids o f p lag -ch l -ep d i r e c t e d along the main f o l i a t i o n {DJJM00,LOC-J59} F igure 16b - Mat r ix -suppor ted b recc ia w i t h d i o r i t e and massive hnbd c l a s t s elongate i n the d i r e c t i o n o f the main f o l i a t i o n {DIR-090, LOC-J60} Page 34 structural Geology of Part of the Crooked Lake area. Quesnel Highlands. British Coluwbia Figure 16c - C las t -suppor ted conglomerate w i th d i o r i t e c l a s t s t h a t show a weak e longat ion i n the plane of the main f o l i a t i o n {DIR-335, L0C-J144} F igure 16d - Folded contact between vo lcan ic 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 the Crooked Lake P h y l l i t e , i s f u l l y contained w i t h i n the Takla Group rocks {DIR-318, L0C-J163} Page 35 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia sandstones and mat r i x -suppor ted breooias g ive way t o c las t -suppor ted conglomerates. Th is l i t h o l o g y probably o r i g i n a t e d as in te rmed ia te vo lcan ics and associated v o l c a n i c l a s t i c s i n an i s l a n d arc s e t t i n g . A shor t excurs ion i n t o a c i rque on the no r th l imb o f the Eureka Syncl ine showed a considerable s i ze body o f f a i r l y f r e s h gabbro t o have i n t ruded T a k l a - l i k e rocks. The rock u n i t s a t the base and extending up the s ide o f Eureka Peak were extremely sheared and hydrothermal ly veined. Some oopper m i n e r a l i z a t i o n was associated w i t h t h i s ve in ing and an a d i t some 20 meters long had been excavated 100 meters f rom the base o f the peak. Page 36, Structural 6eology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia STRUCTURE I n t r o d u c t i o n Deformat ional episodes have l e f t an obvious i m p r i n t on the Crooked Lake rock u n i t s . Some prominent e f f e c t s o f these events inc lude t r a n s p o s i t i o n o f pr imary bedding, development o f secondary composi t iona l l a y e r i n g , s t rong mica or amphibole 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 f r a c t u r i n g . Many of these de fo rmat iona l l y der ived sur faces (and some o r i g i n a l ones) e x h i b i t f o l d forms t h a t are excep t i ona l l y common throughout the rock mass as w e l l . A d d i t i o n a l f ea tu res such as my lon iza t ion , l i n e a r f a b r i c s , boudinage, ve in ing ( c a l c i t e , quar tz , and/or ep ido te ) , and f a u l t i n g are e i t h e r l ess conspicuous i n nature or only o f l o c a l importance. Analys is o f these s t r u c t u r a l elements a l lows one t o decipher the s t r u c t u r a l h i s t o r y o f an area. On the scale o f a s i n g l e outcrop measurements o f the o r i e n t a t i o n s o f the var ious s t r u c t u r a l f ea tu res were taken and the 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 la te 2 ) ; a r e l a t i v e t ime sequence of f e a t u r e s was then 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 e x i s t . Extending t h i s type o f a n a l y s i s t o the grea ter map scale invo lves dec id ing which fea tu res a t one l o c a l i t y r e l a t e t o o thers elsewhere. Because 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 , d i f f e r e n t o r i e n t a t i o n s , or may on ly be l o c a l l y developed, the t ime sequences noted a t the lesser scale together w i t h knowledge o f major contact d i s t r i b u t i o n s form the basis o f the i n t e r p r e t a t i o n o f the o v e r a l l geometry ( r e f e r t o Cross Sect ions, P la te 3) and developmental h i s t o r y i n t he rock mass as a whole. An impor tant assumption t h a t had t o be made t o a l low the b r i d g i n g o f smal l scale observat ions t o l a rge scale Page 37 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia i n t e r p r e t a t i o n s 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 sur faces) seen i n outcrop have s i m i l a r coun te rpar ts i n the l a r g e r dimension. TABLE I C h a r a c t e r i s t i c F e a t u r e s o f t h e F i v e Phases o f D e f o r m a t i o n a t Crooked Lake Respective _Events t General Characteristics Preferred Terwinology 05 04 03 02 831 {02} {01} 6 01 0 DO DO Takla 6p. Antler Fn. Crooked Lake Phyl. Snowshoe fw. Eureka Qztite. Northeast directed faults and fracture sets S5 Gentle to open folds and kink folds (wostly of S2); reclined (Oomain I) and upright plunging (Domain II) F4 symmetry plane of folds, kink band boundary planes S4 hinge line of folds, ext. rot. axis of kinks L4 Open to wediuw folds; upright plunging (Dowain ^ symmetry plane of folds, spaced cleavage S3 hinge line of folds, weak to strong crenulation lineation L3 Open to very tight folds; upright plunging (Domain I) and recuwbent to inclined plunging (Dowain II) F2 symmetry plane of folds, strong nica/awphibole foliation, ueak gneissic layering and/or lensoid development, localized cleavage to spaced cleavage S2 hinge line of folds, strong crenulation lineation, quartz rod lineation, localized awphibole lineation 12 Isoclinal, intrafolial. rootless folds,- nearly cowpletely transposed II to 02 features F1 symmetry plane of folds, foliation or cleavage lying closest to compositional layering and/or with strongly crenulated forw SI hinge line or folds, weak sulfide sneer lineation LI Compositional layering, original bedding SO 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 lead the present author t o group the Crooked Lake deformat iona l f ea tu res i n t o f i v e d i s t i n c t sets o f s t r u c t u r a l elements (see Table I above) each of which can be r e l a t e d t o a s i n g l e event i n t ime (D1 t o D5); Table I o u t l i n e s these f i v e episodes, t h e i r c h a r a c t e r i s t i c f ea tu res , and the p r e f e r r e d terminology used i n the f o l l o w i n g d iscuss ion (please note t h a t events are numbered w i t h re ference t o t he o ldes t u n i t s ) . Page 38 Figure 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 across the Crooked Lake area; Domains I and I I are separated by the Boss Mtn. A n t i c l i n e ; major contacts 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 Sect ions Data c o l l e c t e d f o r the map area i s presented on the S t ruc tu re Map (P la te 2 ) . I n d i v i d u a l measurements f o r the var ious poss ib le s t r u c t u r a l fea tu res are i n d i c a t e d by an ar ray o f symbols as shown i n the legend and p l o t t e d as near t o the s t a t i o n l o c a t i o n s (see Geologic Map, P l a t e 1) as poss ib le . The m a j o r i t y of these measurements 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 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 t h i s reason t h a t an attempt has been made t o emphasize t h i s dominant f a b r i c ( l i g h t dashed l i n e s w i thout double arrows). The form of these sur faces was determined by f o l l o w i n g the t rends o f mapped data and were assumed t o be p ro jec ted onto a f l a t h o r i z o n t a l p lane; topography has not been considered w i t h respect t o t h i s f e a t u r e ! Since these sur faces represent a p e n e t r a t i v e f e a t u r e (down t o the microscopic sca le ) , the number o f sur faces and the d is tances between them are a r b i t r a r y ; the choice was made so as t o c l e a r l y show the bas is form, wh i le not obscur ing other f ea tu res on the map. Also inc luded on t h i s map are t races o f a x i a l sur faces 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 impor tant set o f f ea tu res , i n a d d i t i o n t o the s t rong f o l i a t i o n f a b r i c , i s shown i n F igure 17; across the area, w e l l developed f o l d s occur t h a t show a very c lose 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 the dominant f a b r i c (compare w i t h P la te 2 ) . Examination o f these forms revealed t h a t the sur face being fo lded was c o n s i s t e n t l y a pr imary one, i n the case o f the upper th ree u n i t s (Eureka Quar tz i te , Crooked Lake P h y l l i t e , and Takla Group), which makes the f o l d i n g event associated w i t h these forms and the 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 ) ; the A n t l e r and the Snowshoe, on the other 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 ) . These r e l a t i o n s h i p s Page 40 Structural fieology of Part of the Crooked Lake Area, Quesnel Highlands, British Colunbia are shown i n F igure 17 by sur face des ignat ions ( e . g . the dominant f o l i a t i o n i s 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 cross sec t ions (P la te 3) were der ived f rom fea tu res and measurements t h a t cross the two s e c t i o n l i n e s shown on P la te 2. The remainder o f the sec t ions i s p a r t i a l l y p ro jec ted from the S t r u c t u r e Map and p a r t i a l l y i n t e r p r e t e d f rom known f a c t s concerning the character o f de format iona l forms a t the outcrop scale. An impor tan t p o i n t t o note concerning these sec t ions i s the r e l a t i o n s h i p between the two f o l d forms o u t l i n e d by the major oontacts . O r i g i n a l l y , the an t i fo rm/syn form p a i r (here designated the Basse t t /S ta rk p a i r ) t o the west was be l ieved t o be p a r a s i t i c t o t he Boss Mountain A n t i c l i n e (K.V. Campbell 1971). The present author holds t h a t t h i s cannot be the case. A l l minor f o l d forms t o the west ( r e f e r t o F igure 17) w i t h o r i e n t a t i o n s s i m i l a r t o the Basse t t /S ta rk p a i r ( u p r i g h t - p l u n g i n g ) are always found associated w i t h the pervasive f o l i a t i o n , S2, i n an a x i a l p lanar r e l a t i o n s h i p . This se t o f sur faces (see P la te 2) i s c l e a r l y not f o l d e d about the Basse t t /S ta rk p a i r , but l i e s i n an a x i a l p lanar r e l a t i o n s h i p t o them, as w e l l . The f a c t t h a t f o l d forms t o the east (see F igure 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 t o those i n the west have the same a x i a l p lanar r e l a t i o n s h i p t o the main f o l i a t i o n , S2, and here l i e i n a 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 ives credence t o the suggest ion t h a t forms associated the Basse t t /S ta rk p a i r are a c t u a l l y f o lded over the Boss Mountain A n t i c l i n e (which i s , t hus , i n t e r p r e t e d as a 03 f e a t u r e ) . Domains As the S t ruc tu re Map and Cross Sect ions, P la tes 1 & 2, show. Crooked Lake f o l l o w s the t r a c e o f the a x i a l sur face o f the D3 Boss Mountain A n t i c l i n e (K.V. Campbell 1971), and accord ing ly can be used as the d i v i d i n g l i n e between two Page 41 Structural Geology of Part of the Crooked Lake Area^ugsnejJjighlMds, British CoTmhi, Domain I I - east limb of 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 Figure 18a - Contour p l o t s of 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 points per 1% stereonet area) Page 42 Structural geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia N Domain II N \ o -BP 'AN' SN Boss Mounta in A n t i c l i n e Scali • • • • 1 liloaetsrs Domain Figure 18b - Contour p l o t s o f poles t o composi t iona l l a y e r i n g (bedding?) and envelopping sur faces o f D2 f o l d s (contours 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. the west and east l imbs of 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 poles t o the S2 f o l i a t i o n shown i n F igure 18a (and t o a lesser ex ten t the contour p l o t s o f composi t ional l a y e r i n g i n F igure 18b) i l l u s t r a t e t h a t the re 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 regions ( t o the southwest t he S2 f o l i a t i o n planes average 1 6 5 ° / v e r t i c a l and t o the nor theast 110°/50 QNE). Th is d i f f e r e n c e , then, forms the basis f o r a breakdown o f the Crooked Lake data i n t o two main Domains, I , t o the southwest and, I I , t o the nor theast (see Figure 17). The f o l l o w i n g i s a d isouss ion o f each o f the phases o f deformat ion as they were observed as minor f e a t u r e s i n the f i e l d and r e f l e c t e d i n the o v e r a l l l a rge -sca le map-pat tern. Cons idera t ion has been given as t o how each phase has e f f e c t e d the f i v e d i f f e r e n t u n i t s , t h e i r contac ts , and e a r l i e r surfaces i n each o f the two Domains. Thin sec t ions were examined t o cor robora te , where poss ib le , mesoscopic f i e l d observat ions and t o prov ide i n f o r m a t i o n r e l a t i n g minera l growth and deformat ion h i s t o r i e s . Phase One This e a r l y phase i s not represented t o t a l l y throughout the l i t h o l o g i c / 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 of f o l d i n g was found by the present author only i n the A n t l e r Formation (see F igure 19), though K.V. Campbell (1971, p.173) shows good examples o f r o o t l e s s , i n t r a f o l i a l i s o c l i n e s invo lved i n what appear t o be medium, phase two f o l d s i n Snowshoe ( i n the f o l l o w i n g d iscuss ion, the 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 the i n t e r l i m b [ d i h e d r a l ] angles: 180-120°, 120-60°, 60-20°, 20-0° , r e s p e c t i v e l y ) . I n the upper t h ree u n i t s evidence f o r t h i s phase does not e x i s t ; t h i s would imply t h a t Page 44 Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Figure 20 - I s o c l i n a l f o l d c losure i n v o l v i n g composi t ional l a y e r i n g o f qtz-musc marble and p lag-musc-b io-q tz s c h i s t {DIR-330, L0C-J74} Page 45 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Coluwbia a - Equal-area net p l o t o f poles t o a x i a l sur faces o f D1 f o l d s f rom both Domains Equal-area net p l o t o f D1 f o l d hinges f rom both Domains t = t (mm)/ to (mm) c - t - a l p h a p l o t o f D1 Fold Forms Snowshoe J72, J74, J74b, A n t l e r RZ6; (see Appendix C f o r exp lanat ion of f o l d form curves) 0 10 20 30 40 50 60 70 80 90 A lpha = a° F igure 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 depos i t i on (o r emplacement) o f these u n i t s post -date phase one deformat ion o f the lower two u n i t s . The most t y p i c a l forms represen t ing D1 i n the Snowshoe and A n t l e r are 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 o f composi t iona l l a y e r i n g and/or bedding (F igure 20 and P la te 6 f ) ; most o f t e n these forms are very smal l , r o o t l e s s fea tu res ( they take up l e s s than 1 or 2 sq. dm.) embedded i n a h i g h l y f o l i a t e d and compos i t iona l ly st reaked mat r i x . An S1 mica f o l i a t i o n i s best seen as a transposed fea tu re i n t h i n sec t ions o f Snowshoe rocks f rom Domain I (see F igure M1). I n the f i e l d t h i s f e a t u r e i s c e r t a i n only when i n t e r f e r e n c e o f D1 fea tu res 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 form and S2 occurs as a prominent spaced c leavage). F igure 21 summarizes the o r i e n t a t i o n and form data f o r D1 f o l d s f rom the Snowshoe and A n t l e r . The r a r i t y o f such forms i n the area mapped i s r e f l e c t e d i n the very smal l number o f data p o i n t s ; never the less, the o r i e n t a t i o n o f these f o l d s (F igure 21a, b) l i e s w i t h i n the range o f ) D2 f o l d data (F igure 25 ) which r e f l e c t s the near complete t r a n s p o s i t i o n o f D1 sur faoes t h a t was observed i n the f i e l d . The t - a l p h a p l o t ( technique f rom Ramsay, 1967; see Appendix C f o r exp lanat ion and data) o f D1 f o l d forms (F igure 21c) shows a d i s t r i b u t i o n o f po in t s t h a t suggests Class 2 t o Class 3 type f o l d s w i t h very low i n t e r l imb angles (« 15°) . I n t e r f e r e n c e forms between D1 and D2 observed i n the map area are shown i n F igure 19 and P la te 6h; forms between D1 and o ther events were not seen. F igure 19 and P la te 6h show D1 f o l d s o f composi t ional l a y e r i n g wrapped about D2 medium f o l d s . The r a r i t y o f such forms i s be l ieved the r e s u l t o f the s t reng th and pervasiveness o f the D2 deformat ion. Page 47 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Large scale f e a t u r e s t h a t might o u t l i n e the e f f e o t t h a t t h i s deformat ion has had on the rock u n i t s a t Crooked Lake are not d e f i n i t i v e . T igh t i n t e r f i n g e r i n g o f the Snouishoe/Antler contac t i n Domain I I near ly always shows the same c h a r a c t e r i s t i c s as t he sur face above ( the Eureka/Ant ler 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 l a rge enough p r o f i l e sect ions o f these sur faces were never observed so the present author can o f f e r no con f i rma t ion or den ia l o f poss ib le m u l t i p l e f o l d i n g o f t h i s sur face. Zones o f my lon i te w i t h i n the Snowshoe were always seen invo lved i n D2 f o l d i n g and may be a r e s u l t o f D1 deformat ion and/or some per iod 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 the Snowshoe, w i t h c a r e f u l a t t e n t i o n pa id t o s t r a t i g r a p h y might be able t o d iscern the complex nature 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 t o r e l a t e the f i r s t phase minor forms seen a t Crooked Lake w i t h ones f rom areas t o the east and south (Ghent e t a l . 1977; Murphy and Journey 1982; P e l l and Simony 1982), such mapping should have a broad a r e a l ex ten t . Phase Two E f f e c t s o f the second deformat ion vary most ly as a r e s u l t o f l i t h o l o g i c v a r i a t i o n . Th is 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 ea tu res i n each major u n i t and between subun i ts where rheo log ic heterogenei ty i s impor tant . I n a general sense a l l major u n i t s d i sp lay some degree o f i n t e r n a l heterogenei ty and so a l l can be expected t o show the f u l l range of elements poss ib le f o r the D2 event; the d i f f e r e n c e between major u n i t s observed was thus one of r e l a t i v e abundance o f the var ious f e a t u r e s . By f a r , the Crooked Lake P h y l l i t e shows the most va r ied set o f 02 f e a t u r e s wh i le the Eureka Q u a r t z i t e and Snowshoe show the l e a s t ( the A n t l e r Formation and the Takla Group l i e somewhere midway). Page 48 structural ecology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia The l e x t u r a l f e a t u r e assoc ia ted w i t h the D2 event t h a t occurs most 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 or amphibole f o l i a t i o n and at tendant composi t ional l a y e r i n g . Th is 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 Figure 22 - Equal area net p l o t o f poles t o p lanar measurements f rom a s i n g l e S2 f o l i a t i o n sur face a t RZ11 i n the 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 sur faces across the area form (F igure 22 shows an equal area net p l o t o f poles t o p lanar measurements f rom a s i n g l e f o l i a t i o n su r face ) 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 compos i t iona l l a y e r i n g accompanies t h i s f o l i a t i o n i n a p o s i t i o n near p a r a l l e l t o i t ; t h i s l a y e r i n g may be m i l d l y cont inuous f o r a shor t d is tance (on the order o f decimeters t o a meter a t most) , but i s s t reaky and Page 4Q Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. Br i t ish Coluwbia F igure 23a - Upr ight 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 ; the s igmoida 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 igure 23b - Upr ight t i g h t s i m i l a r f o l d t runca ted on the r i g h t against planar f o l i a t e d p h y l l i t e {DIR-350, L0C-J36} Page 50 structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Figure 24 - t - a l p h a p l o t s o f D2 f o l d s t = t (mm)/ to(mm) 1.50 i 1 0 10 20 30 40 50 60 70 80 90 A lpha = a 0 a - Open f o l d s a t J40, J89, J57, RZ8; (curves expla ined i n Appendix C) t = t (mm)/ to(mm) 1.50 i 1 0 10 20 30 40 50 60 70 80 90 A lpha = a° t = t (mm)/ to(mm) 1.50 I 0 10 20 30 40 50 60 70 80 90 A lpha = a° b - Medium f o l d s a t J41, J5, RZ5, RZ6,RZ7,RZ10 t = t (mm)/ to (mm) 1.50 i 1 0 10 20 30 40 50 60 70 80 90 A lpha = a° c - T igh t f o l d s f rom J26, J117, J36, d - Basse t t /S ta rk p a i r taken from J26b, J41b P la te 3, Cross Sect ion 1 Page 51 S t r u c t u r a l Geology of P a r t of the Crooked Lake Area, Quesnelj|iohlands, B r i t i s h Colunbia w X-a - Po les t o S2 a x i a l p l a n e s o f minor f o l d fo rms f r o m Domain I (0 & 10% per 1% a r e a c o n t o u r s shown) n V r" 1 - 7 TK /•••.^•::::x I P , : : : : r V X / c - L2 f o l d h inges f r o m Domain I . / ( 0 , 5 , 1 0 , 1 5 % per 1% a rea c o n t o u r s shown) F i g u r e 25 - D2 f o l d e lements f r o m Domains I & I I shown as c o n t o u r p l o t s Page 52L b - Po les t o S2 a x i a l p l a n e s o f minor f o l d fo rms f r o m Domain I I (0 . 1 0 , 2 0 , 3 0 % per 1% a rea c o n t o u r s s h o w n ) / \ /~r>-1 0 1 lilMeters d - L 2 , f o l d h i n g e s f r o m Domain I I (0 & 10% per 1% a r e a c o n t o u r s shown) \ \ Structural ecology of Part of the crooked Like Area, Quesnel Highlands. British Colunbia Figure 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 form) {DIR-345,L0C-J171} Page 53 structural 6eology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia discont inuous over a l l . Lensoid fo rmat ion f rom boudinage o f more oompetent subuni ts accompanies or makes up a s u b s t a n t i a l p o r t i o n o f t h i s l a y e r i n g ; the shape of these bodies can range f rom d iscs t o smal l i s o l a t e d f o l d hinges (P la te 6 i ) t o cont inuous, though h i g h l y a t tenuated f o l d forms (one seen could be fo l lowed f o r 12 meters and had < 2 cent imeter t h i c k l i m b s ) . Occasional ly the l a y e r i n g i s r e p e t i t i v e enough t o develop t i g h t f o l d forms (F igures 23b, 26b) whose a x i a l plane l i e s p a r a l l e l t o t he main f o l i a t i o n . This 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 igure 14) forms a ma t r i x f o r vo lumet r ic regions where l i t h o l o g y i s not as homogeneous. Here, l a y e r i n g tends t o be more cont inuous (on the order o f meters) and a s t rong cleavage occurs as the dominant D2 s t r u c t u r a l element (see F igure 23a). The l a y e r i n g shows d i f f e r e n t types 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 t o the S2({S1}) cleavage (see F igures 23a & 26a). The s i ze 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 lack o f s u f f i c i e n t exposures where they occur, but t h e i r shape i s most o e r t a i n l y l e n s - l i k e - t he long dimension runs p a r a l l e l t o S2 cleavage and S2 f o l i a t i o n i n the ma t r i x . Groups o f these zones ( i f we can assume t h a t t h e i r long dimension i s s h o r t e r than the average d is tanoe between exposures) appear t o be d i s t r i b u t e d p a r a l l e l t o the major con tac ts , except i n the v i c i n i t y o f the Basse t t /S ta rk an t i fo rm/syn fo rm p a i r (where they are near perpendicular t o c o n t a c t s ) . 02 f o l d forms have been grouped i n t o th ree types o f forms: t i g h t , medium, and open corresponding t o the most s i g n i f i c a n t l y d i f f e r e n t l e v e l s o f heterogenei ty observed. F igure 24 shows t - a l p h a p l o t s o f each of these forms. The t i g h t forms (24c) f a l l between the Class 2 t o Class 3 ca tegor ies , the in te rmed ia te forms (24b) are Class 1 t o Class 2 f o l d s , and the open f o l d s (24a) f a l l i n t o Class 1. The Page 54 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 the amount o f f o l d o losure and degree of l imb a t t e n u a t i o n ; i n comparison t o D1 f o l d s , the t i g h t f o l d s are not so c l e a r l y i s o c l i n a l , though they do show q u i t e s i m i l a r values f o r l imb a t t enua t i on . The r e l a t i v e l y wide spacing t h a t occurs between S2 cleavage sur faces o f open f o l d s causes more phys ica l d i s r u p t i o n o f the l aye rs than any appreciable l imb t h i n n i n g (F igure 23a) ; as a consequence these f o l d s show r e l a t i v e l y constant l imb th ickness . A p i c t o r i a l demonstrat ion o f the c o n t r a s t i n g o r i e n t a t i o n s o f D2 deformat iona l elements i s presented i n F igure 17 (a l so see F igures 23 & 26) . Wi th in each o f the two Domains, S2 f e a t u r e s (here represented 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 rom a v e r t i c a l o r i e n t a t i o n i n Domain I and f rom a shal low nor theast d ipp ing o r i e n t a t i o n i n Domain I I . Contour p l o t s o f poles t o these planes f rom Domain I (F igure 25a) i n d i c a t e an approximate maximum i n a v e r t i c a l p o s i t i o n ; the spread of t h i s data suggests t h a t these planes a l t e r n a t e f rom steep east d ipp ing planes w i t h s t r i k e s f rom 110°-135° bear ing t o steep west d ipp ing planes w i t h s t r i k e s f rom 135°-170° bear ing. F igure 25c shows the plunge of 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 lunging 45°-50° . The Domain I I p l o t (F igure 25b) shows a more constant 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 ipp ing 45°-50° t o the 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 the l a t e r th ree deformations ( i . e . D3 and D4). I n Domain I , a combination o f the D3 and D4 events i s be l ieved t o cause the wavy form o f S2 shown i n F igures 22 & 25. D3 causes the s t rong sub -ho r i zon ta l c r e n u l a t i o n s on S2, wh i le D4 i s responsib le f o r n e a r - v e r t i c a l c renu la t i ons . Th is sur face i s seen i n outcrop t o be open t o medium Page 55 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia f l e x u r a l l y fo lded by D4 (P la te 6 1 ) ; F igure 31a demonstrates how poles t o S2 spread out along a great c i r c l e whose pole approximates the 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 conta ins 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 igure 27 & P la te 6 j ) . F igure 31b, c show Figure 27 - I n t e r f e r e n c e of recumbent t i g h t phase two f o l d s w i t h up r igh t phase th ree f o l d s ( t o l e f t near quar tz ve in ) {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 ; the data f o r F igure 31b was taken along the extent o f the upper and lower A n t l e r contacts t h a t were o f t e n seen invo lved i n phase th ree f o l d i n g ; the data f o r F igure 31c came f rom the area around Reggie and Alex lakes. K ink ing and very m i l d f o l d i n g of S2 (F igure 32) i s a t t r i b u t e d t o the D4 event 1 s e f f e c t i n Domain I I . On the macroscopic scale the Basset /Stark f o l d p a i r i n Domain I (Cross Sect ion 1, P la te 3) and the r e p e t i t i o n along the A n t l e r (F igures 9b, 12) and P h y l l i t e / T a k l a (Cross Sect ion 2, P la te 3 and Figure 7c) contacts i n Domain I I are be l ieved t o be rep resen ta t i ve phase two s t r u c t u r e s . The form of the A n t l e r Formation, as i t appears i n the Cross Sect ion 1 (P la te 3 ) , i s shown as a Page 56 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. Br i t ish Coluwbia t - a l p h a p l o t i n F igure 24d; t h i s data agrees reasonably w e l l w i t h the smal ler scale t i g h t t o medium D2 f o l d forms (Figure 24b). Phase Three A number o f f ea tu res represent the t h i r d phase o f f o l d i n g i n the Crooked Lake rock u n i t s . The most obvious e f f e c t i s 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 change t h e i r o r i e n t a t i o n s f rom one s ide of Crooked Lake t o the o ther ; t h i s has been i n t e r p r e t e d as f o l d i n g o f D2 elements over the macroscopic Boss Mountain F igure 28 - Upr ight open D3 f o l d i n g o f Ant le r /Eureka contact {DIR-325, L0C-J102) A n t i c l i n e . On the smal ler sca le , exposed contacts across Domain I I o f t e n show an up r i gh t f o l d form (F igure 28) and phase two elements (S2 f o l i a t i o n and t i g h t f o l d forms) are a c t u a l l y seen f o l d e d by t h i s same type of f o l d form (F igure 27 and P la te 6 j ) . I n both domains, s u b - h o r i z o n t a l t o sha l low-p lung ing c renu la t i ons on S2 are ub iqu i tous and occas iona l l y associated 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 basio form o f D3 f o l d s i s shown i n terms o f a t - a l p h a p l o t i n F igure 30c. 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. P la te 6k demonstrates the gradual change i n form t h a t i s c h a r a c t e r i s t i c o f D3 f o l d i n g . This change i n form was observed t o occur i n a d i r e c t i o n perpendicu lar t o the major con tac ts . Cross Sect ion 2 demonstrates t h i s form change w i t h a p a r a s i t i c f o l d t h a t crops out i n the v i c i n i t y o f Reggie and Alex lakes. O r i e n t a t i o n o f impor tant D3 f e a t u r e s i s depic ted i n F igure 29a, b and 30a. A d i s t i n c t i v e spaced cleavage i s the most common 03 p lanar form found through both Domains I & I I (F igure 29) . Comparison o f these sur faces w i t h the a x i a l planes of D3 f o l d forms f rom Domain I I (F igure 30a) show them t o be moderate t o s teep ly -no r theas t d ipp ing sur faces t h a t s t r i k e t o the northwest. L inear f a b r i c s associated w i t h D3 (F igure 29 c, d & 30b) vary i n a regu la r fash ion across the two Domains f rom NNw w i t h a moderate plunge i n Domain I t o Nil) w i t h a sub -ho r i zon ta l plunge along the A n t l e r con tac ts (a l so see F igure 31b,c) t o NW w i t h a moderate plunge near Reggie and Alex lakes. The i n t e r f e r e n c e of D3 elements w i t h younger events i s not immediately d e a r , e s p e c i a l l y f rom outorop ana lys i s . I t i s poss ib le t h a t the change i n plunge of D3 l i n e a r forms (compare F igures 31b and 31o) may be a D4 e f f e c t . The form suggested f o r the Boss Mountain a n t i c l i n a l a x i a l sur face shown i n P la te 2 i s meant t o show the same k in d o f D4 warping seen throughout the dominant D2 f a b r i c across the area. Besides the Boss Mountain A n t i c l i n e , the only o ther macroscopic 03 form observed was the f o l d form shown i n Cross Sect ion 2 (P la te 3 ) . The change of o r i e n t a t i o n t h a t occurs t o numerous D2 fea tu res (S2 f o l i a t i o n s , f o l d forms) i n t h i s area i s gradual and d e l i b e r a t e . Refolded f o l d forms and u p r i g h t f o l d s o f contacts o f a number o f i n t e r n a l hor izons are common i n t h i s area (F igure 30b). Page 58 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 t h e 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 . B r i t i s h C o l u n b i a A 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 (0 & 10% per 1% a rea ' k - - k ^ . c o n t o u r s shown) 1 ;3 . y 1 / I 1 / "V-C: V. / • •. -\ ..' ' ' c - L3 c r e n u l a t i o n l i n e a t i o n s om Domain I ( 0 , 5 , 1 0 % per 1% a rea c o n t o u r s shown) F i g u r e 29 - D3 c l e a v a g e s and c r e n u l a t i o n s f r o m Domains I & I I shown as c o n t o u r p l o t s Page 5 9 b - Po les t o S3 c leavages f r o m Oomain I I ( 0 , 5 , 1 0 . 1 5 % per 1% a rea c o n t o u r s shown) .~-\_ A n t i c l i n e 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 per 1% area c o n t o u r s shown) ^ • i p ; / Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia a - Contour p l o t of poles t o a x i a l planes of 03 f o l d forms from Domain II (0,5,10% per 1% area contours shown) mm -b - Contour p l o t of f o l d hinges to D3 f o l d forms from Domain I I (0,5,10,15,20% per 1% area contours shown) t = t(mm)/to(mm) 1.50 1.40 1.30 1.20 h 1.10 1.00 . 9 0 h . 80 . 7 0 . 6 0 .50 I-.40 . 3 0 .20 (-.10 . 00 no &s,a DO • ^ J I c - T-alpha p l o t of 03 Fold Forms C L . P h y l l i t e J98, J104, J117; curves explained i n Appendix C 0 10 20 30 40 50 60 70 80 90 A lpha = a " Figure 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 60 Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Figure 31a - Combined data p l o t (equal area) t o show t y p i c a l spread of 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 D4 fea tu res f rom Domain I (D1 fea tu res inc luded) + S4 A x i a l Planes ffl S2 F o l i a t i o n • S2 A x i a l Planes * S1 A x i a l Planes o L4 Fold Hinges • L2 Fold Hinges • L1 Fold Hinges Page 61 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia Figure 31b - Combined data p l o t (equal area) showing r e l a t i o n s h i p between D2 and D3 fea tu res i n Domain I I along upper and lower A n t l e r contac ts (J85—>J114) S2 F o l i a t i o n 52 A x i a l Planes 53 A x i a l Planes L2 Fold Hinges L3 Fold Hinges Page 62 Figure 31c - Combined data p l o t (equal 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 i n the northeastern-most p a r t o f t he map area (J142—>J171) ffl S2 F o l i a t i o n • S2 A x i a l Planes • S3 A x i a l Planes L2 Fold Hinges • L3 Fold Hinges Page 63 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia Figure 32a - Double kink of 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} Figure 32b - Clockwise 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 of P a r t of the Crooked Lake Area, Quesnel Highlands, B r i t i s h Columbia m 1 a - Po les t o S4 a x i a l p l a n e s o f minor f o l d fo rms f r o m Domain I \ ( 0 , 1 0 , 2 0 * per U a rea c o n t o u r s shown) mm* 4 TK •X ? / c - L4 f o l d h i n g e s f r o m Domain I \) / (0 & 10% per n a rea c o n t o u r s shown) 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 shown as c o n t o u r p l o t s b - S4 k i n k band boundry p l a n e s ^ f r o m Domain I I (0 & 5 0 * per 1% a rea c o n t o u r s shown) A n t i c l i n e i o i Kileactars d - L4 k i n k axes f r o m Domain I I (0,30% per 1% a rea c o n t o u r s shown) / / f t i Page 65 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia Figure 34 - St ress de terminat ion of D4 episode f rom deformed S2 f o l i a t i o n s ( f rom Car ter & Rale igh, 1969) Haximin conpressive m stress Pole of deforned plane External rotation toward naxlHun conpressive stress • S2 Foliation (5> Deforned S2 Foliation * Kink Band Boundries t7rlaxinun Conpressive Stress Deternination Pole of original plane According to experimental data (left) when surfaces are in a position of high shear, they H i l l 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 rom the f o u r t h deformat ion d i f f e r l a r g e l y as a f u n c t i o n o f the f a b r i c w i t h i n each o f the domains. I n Domain I , where the S2 f o l i a t i o n i s c lose t o 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 occur r ing as conjugate p a i r s ) w i t h steep hinges (55°-65° t o the 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 igure 33a, c & P l a t e 6 1 ) ; these f l e x u r a l s t y l e f o l d s q u i c k l y d ie out i n ampl i tude w i t h i n a few meters a t most. To the nor theast i n Domain I I , conjugate k i n k i n g o f t he S2 f o l i a t i o n i s the c l e a r e s t recognizable D4 e f f e c t . The plunge of very gen t le f o l d s associated w i t h these k inks i s gent le t o t he nor theast ( l i k e the d ip o f t he f o l i a t i o n ) and the k ink bands are steep t o v e r t i c a l and s t r i k e N (F igures 32a, b) and are never more than a few cent imeters i n w id th . F igure 34 shows a de te rmina t ion o f poss ib le D4 maximum compressive s t r e s s o r i e n t a t i o n s us ing the technique o f Car ter & Rale igh, (1969) f o r k ink banding. R e l a t i v e t o the present o r i e n t a t i o n o f t he S2 f a b r i c i n Domain I I t he 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 he maximum compressive s t r e s s s l i g h t l y i n c l i n e d toward the south east . Late B r i t t l e Phase Late h igh angle f a u l t i n g o f the A n t l e r Formation contac ts has been mapped by Campbell, R.B. (1978) and Campbell, K.v. (1971) t o the south near t o the nose of Eureka Syncl ine ( the p a i r o f t he Boss Mountain A n t i c l i n e ) . I t appears as though the northwest s ide has moved southwestward r e l a t i v e t o the southeast s ide . The o r i e n t a t i o n o f t h i s f e a t u r e i s s i m i l a r ( i . e . v e r t i c a l , s t r i k i n g NE) t o the maximum shown f o r f r a c t u r e s i n Domain I (F igure 35a). To the nor theast an e n t i r e l y d i f f e r e n t maximum, shown i n F igure 35b, t u r n s out t o be associated w i t h conjugate Page 67 Structural Geology of Part of the Crooked Lake ftrea. Quesnel Highlands. British Colunbia Figure 35 - Contour p l o t s of poles to f r a c t u r e s from Domains I & I I (contours represent 0,5,10% of pts 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 throughout Domain I I ; the 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 sets contained 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 the rocks due t o some or a l l o f the e a r l i e r deformat ions. Northwest t r e n d i n g f a u l t s have been loca ted i n adjacent regions (Montgomery, 1978; F le t che r , 1972) w i t h some degree of displacement. I n f a c t , the l i n e a r t r e n d of Crooked Lake combined w i t h the extremely steep slopes t o the nor theast i s suggest ive t h a t a t l e a s t a prominent f r a c t u r e zone may be pos i t i oned the re . I t i s s e r i o u s l y doubted, though, on the bas is o f the s t r a t i g r a p h i c c o n t i n u i t y o f the Crooked Lake u n i t s t h a t any considerable separat ion has taken place i n t h i s area. S t r u c t u r a l Summary Emplacement o f the A n t l e r Formation onto the Snowshoe may or may not have been associated w i t h D1 f o l d i n g . The present author has chosen t o present t h i s p o s s i b i l i t y i n the schematic summary (F igure 36) , but the 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 lso poss ib le t h a t each u n i t c a r r i e d w i t h i t a unique episode of deformat ion t o t h e i r coup l ing l o c a t i o n . I t seems t h a t the f i r s t deformat ion has not a f f e c t e d the sur face separat ing the Snowshoe and the A n t l e r , which leads the present author t o be l ieve t h a t t h i s sur face i s e i t h e r contemporaneous w i t h or pos t -da tes D1 f o l d s (a t h r u s t f a u l t genesis could exp la in t h i s temporal r e l a t i o n s h i p ) . An h ia tus presumably separated the e a r l i e s t event a f f e c t i n g the Snowshoe and A n t l e r Formations f rom the eventua l emplacement o f the th ree youngest u n i t s . Again i t i s not known whether t h i s emplacement was associated w i t h deformat ion or not ( e . g . t he e a r l y 'open f o l d i n g ' phase of D2 deformat ion could have formed dur ing Page 69 S t r u c t u r a l Geology of P a r t of the Crooked Lake Area, Quesnel Highlands, B r i t i s h Colunbia F i g u r e 36 - Schemat i c s t r u c t u r a l summary, ( a ) A n t l e r F o r m a t i o n i s emplaced 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 , ( b ) The upper t h r e e u n i t s a r e emplaced a t o p t h e l o w e r two p resumab ly 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 a c c o u n t f o r t h e p i n c h i n g o u t o f t h e Eureka Q u a r t z i t e . ( c ) E a r l y s tage o f D2 d e f o r m a t i o n d e v e l o p s p a r a l l e l f o l d s , ( d ) As t e m p e r a t u r e s and degree o f d e f o r m a t i o n i n c r e a s e s , p a r a l l e l 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 o f u n i t s , ( 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 p a t t e r n Page 70 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia emplacement). I t i s c lea r t h a t the D2 deformat ion has a f f e c t e d a l l major oontaots which sets a pre or syn-D2 date on the t ime t h a t the f i v e u n i t s have shared a common h i s t o r y . The second deformat ion represents an extreme i n the k inemat ic h i s t o r y o f the area. P a r a l l e l f o l d i n g o f the rock u n i t s (as evidenced by open f o l d packages) even tua l l y gave way t o more extreme f l a t t e n i n g , shear f o l d i n g , and in tense f o l i a t i o n development (F igure 36 c, d ) . Obviously t h i s event occurred a t a t ime when o v e r a l l t e c t o n i c cond i t i ons were changing, ( the most impor tant o f which was probably increase of temperature) . The major compressive s t resses 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 rom an o r i e n t a t i o n p lunging s l i g h t l y toward the nor theast ; t h i s o r i e n t a t i o n i s suggested by the vergence shown by the D2 Basset /Stark p a i r when they are unfo lded about an average D3 f o l d ax is t o the northwest. The subsequent 03 event i s mainly evidenced by the gross change i n o r i e n t a t i o n o f D2 elements between the two Domains (F igure 36e). I n o ther areas, t o the 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 changing deformat ional s t y l e w i t h depth i n the l i t h o l o g i c p i l e ( i . e . f l a t t e n i n g o f f o l d forms w i t h depth) . I n the present study, s t r a t i g r a p h i c c o n t i n u i t y fo rces 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 rom the f a u l t s separa t ing low and h igh grade zones o f Montgomery, (1978) and the th ickness o f rock considered combined w i t h east /west v a r i a t i o n ( ins tead of n o r t h / s o u t h ) r u l e s out the 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 the Crooked Lake area. Un fo r tuna te ly , t he re remains some s i g n i f i c a n t ambigui ty as t o how the proposed D3 event c o n s i s t e n t l y e f f e c t s D2 elements across the 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 the Boss Mountain A n t i c l i n e and minor f o l d forms from Domain I I are r e l a t i v e l y cons i s ten t w i t h each o ther ; i t should f o l l o w t h a t D3 forms elsewhere are s i m i l a r l y o r i e n t e d . What we see, though, i n Domain I are f o l d forms w i t h the appropr ia te placement and o r i e n t a t i o n , but w i t h assoc ia t ions t h a t very s t r o n g l y suggest these f o l d s are o f the same generat ion as those fo lded by D3 i n Domain I I , i . e . D2 forms! The present author suggests t h a t an unusual o r i g i n a l o r i e n t a t i o n f o r D2 f a b r i o s w i t h i n D3 deformat ion f i e l d s may have al lowed c e r t a i n p a r t s 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 cause s t r a i n t o be taken up by t i g h t e n i n g o f e a r l i e r f ea tu res r a t h e r than c r e a t i n g new ones. D3 forms are be l ieved t o only be represented i n Domain I by oleavages, c renu la t i ons , and the wavy form o f the S2 f o l i a t i o n . The D3 event i s be l ieved t o r e s u l t f rom a compressive maximum s t r e s s d i r e c t e d f rom 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 the southwest; the evidence f o r t h i s i s f rom the vergence o f the Boss Mountain A n t i c l i n e / E u r e k a Sync l ine p a i r as shown on oross sec t ions o f Campbell, K.V. (1971). The l e v e l temperature (and poss ib ly pressure) e x i s t i n g dur ing t h i s event were c e r t a i n l y much lower than dur ing the prev ious episode; i n t h i n s e c t i o n , i t 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 represents 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 could be pos tu la ted f o r the e a r l i e r events, i . e. maximum compression f rom the southeast. I t s e f f e c t d i f f e r e d between the two domains l a r g e l y because o f the o r i e n t a t i o n o f the d i f f e r e n t f a b r i c s ; i n Domain I f o l i a t i o n s and cleavages were favourab ly pos i t ioned f o r f o l d i n g t o take p lace. I n Domain I I f o l i a t i o n s presumably l ay a t an angle t o the maximum compressive s t r e s s t h a t fo rced a la rge amount o f shear ing 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 longer l a s t i n g , i t i s poss ib le t h a t more extensive k ink 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 the Crooked Lake rock u n i t s has been associated w i t h f r a c t u r e sur faces t h a t l o c a l l y occur together as a conjugate set . S u r p r i s i n g l y each Domain i s assoc ia ted w i t h one o f the p a i r ; Domain I conta ins the nor theast s t r i k i n g set and complete ly lacks represen ta t i ves o f the other (see F igure 35a), whereas Domain I I con ta ins most ly the no r th s t r i k i n g se t . Since f a u l t s i n the area most ly belong t o the nor theas t se t , i t i s the most l i k e l y sur face along which movements and breaking cou ld have occurred. Domain I I , however, has provided the D5 s t ress 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 ink band boundary p lanes) , which j u s t happens t o be a conjugate t o the nor theast se t . The l i k e l y s t r e s s f i e l d t o produce these sur faces i s w i t h maximum compressive s t r e s s d i r e c t e d toward the 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, (1951)) . Page 73 Structural Geology of Part of the Crocked Lake Area. Quesnel Highlands. British Colunbia METAMORPHISH I n t r o d u c t i o n The process o f metamorphism i s i n t r i n s i c a l l y r e l a t e d t o deformat ion i n a number o f impor tant ways. I n t he f i r s t p lace both are dependent on e x t e r n a l l y c o n t r o l l e d f a c t o r s such as pressure and temperature and as a consequence should show a systemat ic v a r i a t i o n a t d i f f e r e n t p o s i t i o n s w i t h i n g rad ien t f i e l d s o f these two v a r i a b l e s (pressure inc ludes depth w i t h i n the l i t h o l o g i c / s t r u c t u r a l p i l e ) . Next, i t has been observed t h a t t he phys ica l e f f e c t s o f metamorphism and deformat ion o f t e n r e s u l t i n the same f e a t u r e s , ( e . g . f o l i a t i o n s are formed of metamorphical ly grown mica or amphiboles), and i n the case of both processes, these e f f e c t s are seen t o change as a r e s u l t o f l i t h o l o g i c v a r i a t i o n w i t h i n the e x i s t i n g bodies o f rock. F i n a l l y , t ime bounds the beginning and end o f d i s c r e t e metamorphic and/or de fo rmat iona l events and i n f l uences c e r t a i n ra tes impor tant t o the complet ion o f a process or genera t ion o f e f f e c t s o f a process. Metamorphism, i n genera l , i s concerned w i t h the s e r i e s o f poss ib le reac t ions t h a t can occur t o any composi t ion type f rom the upper l i m i t o f d iagenet ic processes t o the pressures and temperatures where me l t i ng occurs (see Figure 37) ; t h i s inc ludes a l l r e a c t i o n s t h a t i nvo l ve s o l i d phases w i t h or w i thout a vapour phase. These r e a c t i o n s are, o f course, sub jec t t o the laws of k i n e t i c s t h a t a l low f o r the occurrence o f deep-seated minera l assemblages a t the sur face o f the ear th , but as f a r as 'normal* prograde metamorphic processes are concerned t ime i s u s u a l l y not a s i g n i f i c a n t f a c t o r so the theory o f thermodynamic e q u i l i b r i u m can s a f e l y be assumed. The two most impor tant f a c t o r s used t o prove the ex is tence of a poss ib le r e a c t i o n (and accompanying e q u i l i b r i u m ) are the t e x t u r e s w i t h i n and among e x i s t i n g minera 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, WC Figure 37 - 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 the ' P - T ' f i e l d (adapted f rom Turner [1981] p. 420) observat ion of the 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 the phase r u l e : F - C - P + 2 (F i s the degrees o f freedom i n pressure/ temperature space [ t h i s should be one i n the case o f a s i n g l e r e a c t i o n ] , C i s the number o f components i n the system, P i s the number o f phases i n the system, and the 2 r e f e r s t o the two e x t e r n a l l y c o n t r o l l e d f a c t o r s , pressure and temperature) . The phys ica l s i g n i f i c a n c e of Page 75 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia TABLE II-A DISTRIBUTION OF MINERAL ASSEMBLAGES IN 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 L J — S — n — i n 1 R Chl-Graph-Qtz-Musc 0 P Musc-Qtz-Chl-Ank 0 H Cc-Chl-Graph-Qtz-Musc K Y Musc-Chl-Qtz E L Py-Qtz-Kspar Chl-Gn-Staur-I lm-Musc-Qtz D L Chl-Musc-Otz-(Graph) I Qtz-Musc-Ank L T Musc-Ank-Qtz-Chl A E I lm-Graph-Chl-Qtz-Musc K I lm-Chl-Musc-Qtz-Graph L 1 1 1 1 1 1 H Mgt-Chl-Qtz-Ab Musc-Bio-Chl-Ep-Ol ig Py-Musc-Qtz-Ank Ep- I lm-B io -O l ig -Ch l -Qtz Ep- I lm-Chl -Cc-Qtz-Ol ig A Qtz-Mgt-Ep-Chl-Cc-Ab N Chl-Ep-Qtz-Cc-Ab T Cc-Chl-Ep-Ab-Hnbd/Act L Cc-Mgt-Qtz-Chl-Hnbd-Ab-Ep E (Bio)-Ep-Hnbd-Mgt-Chl-Otz R 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-Fels ic-Ep-Hnbd/Act Hnbd-Chl-Ep-Qtz : L_U I L I _ _ . | N H (Ands) - (B io) -Musc- (Chl ) -Qtz 0 0 Qtz-Musc-Cc • E (01 ig ) - (Ch l ) - (Pe r th ) -Musc -B io -Q tz 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 IN DOMAIN I I OF THE CROOKED LAKE AREA NW SE T A Qtz-Hnbd-Ep-Chl-Ab K Chl-Qtz-Hnbd-Ep-Ab L Opaq-Chl-Qtz-Ab A I  n—n 1 rm Hnbd-Ep-Bio-Fels ic-Act C B io -Ep-Ac t -Fe ls i c R Musc-Py-Ab-Qtz-Cc 0 P Musc-Cc-Ank-Ep-Ab-Qtz 0 H Chl-Musc-Otz K Y Chl-Musc-Qtz-Graph E L Musc-Qtz-Chl-Ank Chl-Musc-Qtz-Graph D L Chl-Graph-Qtz-Musc Graph-Chl-Qtz-Musc I Ctd-I lm-Chl-Musc-Ands-Qtz L T Chl-Ctd-I lm-Graph-Ands-Qtz-Musc A E Ctd-Ilm-Gn-Chl-Graph-Ands-Musc-Qtz K Gn-I lm-Ctd-Musc-Chl-Qtz E Chl-Musc-Qtz-Graph Graph-Chl-Cc-Qtz-Musc U U I L L U E Q I 1 ^ u z R T Opaq-Chl-Musc-Bio-Olig-Qtz E I Ep-Hnbd-Bio-Qtz K T Gn-Mgt-Chl-Musc-Bio-Qtz " 1 1 1 1 A I lm-Ep-Parg-Ab-Chl-Bio-Hnbd-Qtz N Cc-Qtz-Ep-Chl-Ab-Hnbd T Ep-Ab-Opaq-Qtz-Hnbd L Opaq-Chl-Ab-Cc-Hnbd-Qtz E (Ands) -Act -C lz-Chl -Qtz R Cc-Ands-Qtz-Clz-Chl Ep-Ands-Hnbd Ep-Felsic-Hnbd Ands-Act-Clz F e l s i c - C l z - A c t 1 1 1 — 1 ! 1 — 1  N ( I lm) -B io -Musc - (01 ig ) -Q tz 0 B io-Musc-Qtz- (Feld) • (01 ig ) - (B io ) -Musc-Qtz S (Musc)-(Gn)-Bio-Qtz H Qtz-Musc-Cc 0 Qtz-Ep-Hnbd E Gn-Bio-Musc-Qtz-Ands I I 1 I Page 77 Structural geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia reac t ions as sur faces and p l a n a r - l i k e volumes can be taken 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 composit ion type. A q u a n t i t a t i v e est imate o f the pressures and temperatures a t t a i n e d dur ing one or more metamorphic events can be est imated by i d e n t i f y i n g or i n f e r r i n g r e a c t i o n assemblages i n t h i n sec t ions or i n the f i e l d and c o r r e l a t i n g these f i n d i n g s w i t h work done on these same reac t ions i n the exper imental pe t ro logy environment ( t h i s w i l l ino lude t h e o r e t i c a l thermodynamic determinat ions as w e l l as r e v e r s a l e q u i l i b r i a exper iments) . Not a l l composi t ion types can be expected t o be use fu l i n t h i s regard f o r some may show minimal ohanges outs ide o f t e x t u r a l readjustment t o the l o c a l s t r e s s cond i t i ons , wh i le o ther types may undergo repeated m i n e r a l o g i c a l and t e x t u r a l t rans fo rmat ions the complexi ty o f which can hard ly be expected t o be reproduc ib le i n the l abo ra to ry environment. I n shor t , one i s faoed w i t h the dilemma of choosing t o observe composit ion types t h a t are s u i t a b l y r e a c t i v e t o prov ide meaningful r e a c t i o n data, on the one hand, wh i le keeping reac t ions and assemblages as simple as i s warranted by cu r ren t t h e o r e t i c a l and exper imental research. U l t i m a t e l y the study o f the metamorphic h i s t o r y o f an area should y i e l d a q u a l i t a t i v e statement o f the r e l a t i o n s h i p between metamorphic and deformat ional events. Th is has been accomplished, i n t he present study, by r e l a t i n g growth o f minera ls as observed i n t h i n sec t ions t o the development o f s t r u c t u r a l f ea tu res known f rom the outcrop sca le . Metamorphism i s be l ieved t o co inc ide w i t h the f i r s t th ree deformat iona l events (see F igure 50) , occur r ing as th ree 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 respect t o o ldes t u n i t s ) . Assemblages c h a r a c t e r i s t i c o f the Crooked Lake u n i t s are o u t l i n e d i n Table I I - A , B (note: minera l names g iven i n ' l e a s t - t o - m o s t ' f o r m a t ) ; the present author Page 78 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia has chosen t o groups these assemblages i n t o f i v e major composi t ional types ( 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 , bas ic , calcareous, 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 the metamorphic l i t e r a t u r e , (Turner [1981] ; Miyashi ro [1973 ] ) . The f o l l o w i n g i s a d e t a i l e d t reatment o f the assemblages corrsponding t o each composi t ional type w i t h cons ide ra t i on g iven p a r t i c u l a r i l y t o poss ib le reac t ions and exper imental suppor t ing evidence; 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. Quar tzo-Feldspath ic Type This composi t iona l type i s charac te r i zed by an abundance of quar tz and fe ldspar s ince rocks o f t h i s type are u s u a l l y der ived f rom ac id igneous rocks or quartzose sedimentary rocks. The Snowshoe and micaceous q u a r t z i t e are composed almost e n t i r e l y of t h i s composi t ion type ; the other th ree u n i t s con ta in moderate t o minor amounts o f q u a r t z o - f e l d s p a t h i c rocks. The most common assemblage seen i n t h i s composit ion domain i s muscovi te-quartz (± 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 igure 38) . The two main minera ls muscovite and quar tz show l i t t l e change across the f i e l d area except i n r e l a t i v e abundance (probably r e f l e c t i n g heterogenei ty o f subun i ts ) and are known t o occur over a wide range o f pressures and temperatures ( f rom upper z e o l i t e t o middle amphibo l i te f a c i e s ; Miyashi ro , 1973). The occurrence of c h l o r i t e , garnet , and b i o t i t e probably represent composi t iona l v a r i a t i o n , though the p r e f e r e n t i a l appearance of c h l o r i t e i n some l o c a l i t i e s and c h l o r i t e - g a r n e t - b i o t i t e i n o thers could be taken as an i n d i c a t i o n o f changing grade. C h l o r i t e seems t o be the so le maf ic minera l i n quar t zo fe ldspa th i c rocks above the Eureka Q u a r t z i t e and the A n t l e r Formation, whereas i n the rocks below and e s p e c i a l l y toward the east and southeast b i o t i t e and garnet Page 79 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Figure 38a - B io -q tz s c h i s t w i t h minor muscovite and porphyroblast o f garnet ; 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 ? ) de f ine 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 igned w i t h S2 f o l i a t i o n def ined by micas { c r o s s - n i c o l s i nse r ted , X12.5,L0C-RZ10} Page 80 Structural Seology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia are o f i nc reas ing importance. React ions i n v o l v i n g the d e s t r u c t i o n o f o h l o r i t e and subsequent fo rmat ion o f b i o t i t e are t y p i c a l o f the upper greenschis t f a c i e s and garnet s t a r t s t o form a t the g reensch is t /amph ibo l i te t r a n s i t i o n (Turner 1968, 1980). P lag ioc lase f e l d s p a r i s e x c l u s i v e l y found i n the groundmass w i t h quar tz . I n Domain I , a l l q u a r t z o - f e l d s p a t h i c u n i t s above the A n t l e r Formation have a l b i t e as the sole p lag ioc lase , whereas p lag ioc lase i n s i m i l a r u n i t s found a t the base o f or below the A n t l e r were found t o range from An22 t o An24. Two po in t s o f cau t ion must be made, however. F i r s t l y , i n terms o f the r e a c t i o n t h a t may be respons ib le f o r t h i s change: a l b i t e + ep idote - 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 epidote 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 the observed p lag ioc lases , and secondly t h e r e i s a very l a rge gap (1 t o 3 km th ickness) between a l b i t e - b e a r i n g and o l i g o c l a s e - b e a r i n g u n i t s where no p lag ioc lase-bear ing q u a r t z o - f e l d s p a t h i c rocks were found. I n Domain I I a l b i t e - b e a r i n g q u a r t z o - f e l d s p a t h i c rocks were found i n the Takla Group rocks and o l i goc lase -bea r ing assemblages were recorded i n the Eureka Quar t z i t e and Snowshoe Formation; a l l o f these occurrences d i d i nvo l ve c l i n o z o i s i t i c epidote, but again the th ickness o f rock between the d i f f e r e n t p lag ioc lase assemblages was la rge (1 t o 2 km). Un fo r tuna te l y an isograd based on t h i s data cannot be c o n f i d e n t l y placed except t o say t h a t the s t r u c t u r a l l y h ighest u n i t i n the p i l e i s on i t s downgrade s ide and the sur face must f a l l somewhere (and w i t h some uncer ta in shape) w i t h i n the mass o f the Crooked Lake P h y l l i t e . Potassium 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 the Crooked Lake area. I n the 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) i s composed of moderately s e r i c i t i z e d or thoc lase w i t h abundant ( m y r m e k i t i c - l i k e ) i n c l u s i o n s o f quar tz . Though r e c r y s t a l l i z a t i o n i s widespread, apparent r e l i c t c l a s t i c g r a i n and cement r e l a t i o n s h i p s are s t i l l d iscernable i n p lane-po la r i zed l i g h t o u t l i n e d by very f i n e opaque m a t e r i a l F igure 39 - B i o t i t e q u a r t z i t e o f Eureka Quar t z i t e w i t h magneti te ve in ing and unusual hornblende c r y s t a l s ; the 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 the more common mica (Plane po la r i zed l i g h t , X12.5,L0C-J104) a t o ld g ra in boundries. The Snowshoe Formation o f Domain I conta ins p e r t h i t e porphyroblasts , again found a t only one l o c a l i t y (RZ10; see F igure 38) . These coarse c r y s t a l s o f t e n con ta in f i n e opaque i n c l u s i o n t r a i l s t h a t are a t a high angle t o and not cont inuous w i t h the main f o l i a t i o n . This f a c t may suggest a metamorphic o r i g i n , imp ly ing t h a t they would have formed a t an e a r l i e r t ime Page 82 structural Geology of Part of the crooked Lake Area, Quesnel Highlands, British Coluwbia than the 02 event a t a grade s u f f i c i e n t f o r K- fe ldspar fo rma t ion ; t he most probable r e a c t i o n f o r t h i s composi t ion type would be: Muscovite + Quartz = K- fe ldspar + Al2Si0s + H2O which f rom the r e v e r s a l e q u i l i b r i a o f numerous workers (Evans 1965, Ke r r i ck 1972, Chat te r jee 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 the upper amphibo l i te 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 lso 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 pr imary mineralogy t h a t has surv ived the var ious metamorphic episodes. Textures i n these rocks are c o n t r o l l e d by the p r i sma t i c nature o f the quar tz and fe ldspa rs . These minera ls are c h a r a c t e r i s t i c a l l y equant t o elongate i n form and so impar t a f o l i a t i o n t o the rock as a whole (F igure 38) , and i t i s not uncommon f o r f e l d s p a r e longa t ion t o be extremely w e l l developed on a l o c a l sca le, as w e l l (F igure 38b). I n t e r n a l deformat ion i n a l l f e l s i c s (undula tory e x t i n c t i o n , deformat ion banding and tw inn ing , p a r t i a l i n t e r n a l g r a i n s u b - d i v i s i o n ) i s always apparent. Micas l i e most ly p a r a l l e l t o the 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 igh 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 Figure 40) probably belong t o an e a r l i e r formed (S1) f o l i a t i o n . Garnets (F igure 38)and magneti te 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 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 together i n veins w i t h quar tz t h a t l i e s u b - p a r a l l e l t o the main f o l i a t i o n (F igure 39 shows magneti te 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 o f a p e l i t i c composi t ion are usua l l y der ived f rom f i n e grained sediments r i c h i n aluminum and potassium; f o r t h i s reason the most common minera ls observed i n p e l i t e s are micas which impart t o the rock a sch is tose or f o l i a t e d t e x t u r e . The Crooked Lake P h y l l i t e i s composed of over 80% of t h i s composit ion Page 83 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia type (F igure 41) , and the Snowshoe's qua r t zo - fe ldspa th io rocks are o f t e n i n t e r l a y e r e d w i t h p e l i t i c s c h i s t s (F igure 40) . F igure 40 - P e l i t i c s c h i s t f rom Snowshoe Fm.; an e a r l i e r f o l i a t i o n S1 has been d is rup ted by the 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 ( top o f photo) and are crossed by S2 muscovites ( c r o s s - n i c o l s , X12.5, L0C-RZ10) Two assemblages are common i n t h i s domain; c h l o r i t e - b i o t i t e -muscovi te-quartz ( t p l a g i o c l a s e ) i s genera l l y t y p i c a l o f Snowshoe p e l i t e s observed, whi le c h l o r i t e - ' g r a p h i t e ' - m u s c o v i t e - q u a r t z ( tga rne t t i l m e n i t e t c h l o r i t o i d t s t a u r o l i t e t p l a g i o c l a s e ) i s c h a r a c t e r i s t i c o f the Crooked Lake P h y l l i t e . The p e l i t i c rocks o f t he Snowshoe vary i n composit ion i n a s i m i l a r way as t h e i r i n t e r l a y e r e d q u a r t z o - f e l d s p a t h i c equ iva len ts . The p ropor t ions of quar tz , muscovite, and b i o t i t e tend t o change unsys temat ica l l y and p lag ioc lase of low t o medium a n o r t h i t e content ( f rom An35 t o An^n) occurs l o c a l l y . The t e x t u r e s o f these rocks are governed by the micas (as opposed t o the f e l s i c s ; compare Page 84 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia bottom and top o f F igures 38 and 40, r e s p e c t i v e l y ) . One dominant f a b r i c and two poor ly represented f a b r i c s were observed. The main f a b r i c corresponding t o the main metamorphic event, has al lowed extensive p a r a l l e l mica growth t h a t def ines the gross ly obvious macroscopic f o l i a t i o n seen across the area. The f i r s t of the less obvious f a b r i c s i s a b i o t i t e ( l ess commonly muscovite) f o l i a t i o n c o n s i s t i n g o f h igh angle ( w . r . t . main f o l i a t i o n ) masses of mica d is rup ted and oross-out by the main f o l i a t i o n (F igure 40) or i s o c l i n a l l y F igure 41 - 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 ye rs have l a r g e amount o f g raph i te t h a t has been i n j e c t e d up i n t o S2 cleavage planes (probably whi le u n i t was s t i l l unconsol idated and wet) ( c r o s s - n i c o l s , X12.5, L0C-J7) f o l d e d arrangements of mica l y i n g p a r a l l e l t o 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 invo lves the growth of muscovite and c h l o r i t e p a r a l l e l t o D3 deformat ional spaced cleavages and appears t o accompany the c r e n u l a t i o n of the main f o l i a t i o n commonly seen across the area; t h i s f e a t u r e i s only seen i n Domain I I o f the Crooked Lake area. Page 85 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia I n the rocks o f the Crooked Lake P h y l l i t e the p ropor t ions o f muscovite, quar tz , and * g r a p h i t e ' vary somewhat i r r e g u l a r l y as does the g r a i n s i ze o f the in te rbeds . The f u l l speotrum o f mica f o l i a t i o n development was observed (see Figures 41 t o 44) f rom microscopic growth p a r a l l e l t o a x i a l planes o f open f o l d s ( w i t h accompanying s o f t - sediment i n j e c t i o n i n t o cleavage planes on the mesoscopic scale, see F igure 41) t o dominat ion o f the t o t a l f a b r i c by the mica f o l i a t i o n ( w i t h accompanying t r a n s p o s i t i o n o f a l l l a y e r i n g s u b - p a r a l l e l t o t h i s f o l i a t i o n . F igures 42, 43, and 44 ) . Th is f o l i a t i o n i s very o f t e n seen c renu la ted , though the ex is tence 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 the Snowshoe) was not observed. I t i s s t r o n g l y be l ieved t h a t M2 (again we could use an a l t e r n a t e terminology, such as {M1}) was the f i r s t metamorphic event t o a f f e c t the Crooked Lake P h y l l i t e . So f a r the minera l assemblages mentioned above do not add any more d e t a i l e d i n fo rma t ion concerning grade than those of the q u a r t z o - f e l d s p a t h i c rocks. I t was, o f course, observed t h a t b i o t i t e seems t o be an impor tant H1 f a b r i c c o n s t i t u e n t (over muscovi te) and t h i s could be taken t o suggest t h a t t h a t event was more or less o f a h igher grade than M2; no more can be sa id o f t h i s e a r l y event g iven 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 observed i n the Crooked Lake P h y l l i t e (see below on d iscuss ion o f s t a u r o l i t e ) , but i s common i n the Snowshoe i s impor tant t o note. I t i s poss ib le t h a t the composit ion o f the Crooked Lake P h y l l i t e i s d i f f e r e n t enough from the Snowshoe p e l i t i c rocks t h a t a t r u e " b i o t i t e 1 i sograd can not be pos tu la ted based on t h i s evidence; the ub iqu i tous occurrence o f c h l o r i t e may i n d i c a t e unusual ly h igh 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 respons ib le f o r the delay o f many b i o t i t e fo rmat ion isograds (Chinner 1960). Page 86 Structural Geology of Part of the Crooked Lake area. Quesnel Highlands. Br i t ish Coluwbia F igure 42b - Microscopic f a b r i c o f po rphy rob las t i c p h y l l i t e showing p lag and i l m porphyrob lasts i n ma 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 porphyrob las ts ; S i i n p lag = S e 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} Page 87 Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Figure 43a - Porphyrob las t ic p h y l l i t e w i t h p lag, c t d , c h l , and i l m i n contac t ; c h l occurs i n center o f c t d c r y s t a l (da rk ) , the corroded form of which con t ras ts w i t h u n i t s where c t d occurs w i t h no p lag {p lane po la r i zed l igh t ,X12.5 ,L0C-J85} F igure 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 de f l ec ted by porphyrob las ts i s cont inuous 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 Figure 44a - Garnet and i l m e n i t e w i t h i n po rphy rob las t i c p h y l l i t e ; garnet shows ro ta ted i n c l u s i o n s t h a t are cont inuous 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 lane p o l a r i z e d l i g h t , X50, L0C-J85} F igure 44b - S t a u r o l i t e i n po rphy rob las 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 the only 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 Cer ta in poor ly de f ined hor izons i n the Crooked Lake P h y l l i t e con ta in assemblages from which s i g n i f i c a n t isograds may be deduced. The bulk o f t h i s p e l i t i c v a r i a n t occurs along the steep southwest slopes o f Ta lbot Ridge i n Domain I I and one occurrence crops out i n t he northernmost p a r t o f Domain I (J47). Th is u n i t i s charac te r ized by po rphy rob las t i c development o f garnet, i l m e n i t e , and p lag ioc lase , c h l o r i t o i d or s t a u r o l i t e w i t h i n a ma t r i x o f c h l o r i t e - m u s c o v i t e -quar tz (F igures 42, 43, 44); t he occurrence o f c h l o r i t o i d or s t a u r o l i t e should be i n d i c a t i v e o f a f a i r l y r e s t r i c t i v e composi t ional range (h igh AI2O3 & h igh Fe/Mg) (Hoschek 1969; H a l f e r d a h l 1961). A l l samples examined conta ined garnet and i l m e n i t e (F igure 44a) together w i t h c h l o r i t o i d , c h l o r i t o i d and p lag ioc lase (F igure 43), or s t a u r o l i t e (F igure 44b). This f i r s t assemblage occurred i n Domain I I w e l l i n t o the mass o f the Crooked Lake P h y l l i t e . C h l o r i t o i d forms coarse, s u b i d i o b l a s t i c , p l a t y c r y s t a l s l y i n g a t low t o moderate angles t o the main f o l i a t i o n and i s h i g h l y inc luded w i t h f i n e quar tz and opaques ( S i p a r a l l e l Se); garnets have a xenob las t i c , se r ra ted o u t l i n e 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 show S i cont inuous t o Se on the outermost c r y s t a l o u t l i n e s ; i l m e n i t e , i n t h i s and a l l specimens, occurs as p l a t y 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 igned w i t h the main mica f o l i a t i o n (h igh angle c r y s t a l s are bent, broken, and/or quar tz pressure shadowed). Nearer t o the lower Crooked Lake P h y l l i t e contact i n Domain I I ( w i t h i n 100-150 meters) the second assemblage i s more predominant. Andesine (An35) i s the most abundant porphyrob last forming augen-shaped c r y s t a l s a l igned w i t h the main f o l i a t i o n w i t h 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 ( S i continuous Se) o f quar tz , i l m e n i t e , tourmal ine , muscovite, and f i n e opaques; c h l o r i t o i d becomes p rogress ive ly more corroded i n the v i c i n i t y o f andesine (Figures 43a, b) Page 90 Structural Seology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia and/or i n samples occu r r i ng f u r t h e r t o the northwest along these steep slopes. The t h i r d assemblage occurs as a s i n g l e exposure i n Domain I ; s t a u r o l i t e , garnet and i l m e n i t e porphyrob las ts occur i n the usual m a t r i x w i t h the a d d i t i o n o f smal l amounts o f b i o t i t e . S t a u r o l i t e i s i d i o b l a s t i c w i t h the long c r y s t a l d i r e c t i o n (Z a x i s ) l y i n g w i t h i n the plane o f the main f o l i a t i o n (F igure 44b shows a l e n g t h - f a s t / e n d sec t i on o f s t a u r o l i t e w i t h S2 perpendicu lar t o the 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 , and poss ib l y represent ing an ax is o f r o t a t i o n (quar tz i n c l u s i o n t r a i l s suggest t h a t S i may be cont inuous w i t h Se); c h l o r i t e i s a common assoc ia te . Garnet c r y s t a l s show i r r e g u l a r weakly inc luded cores w i t h s t r o n g l y inc luded i d i o b l a s t i c r ims. B i o t i t e occurs as xenob las t i c smal l c r y s t a l s . Wi th in the volume spanned by t h i s se r i es o f samples two d i s t i n c t minera l assemblage popula t ions 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 progression i n t ime between the two may or may not have occurred; a r e a c t i o n o f the form: c t d + muse + q tz = s taur + b io + H2O could l i n k the two groups ( t h i s i s most l i k e l y t o occur t o c h l o r i t o i d assemblages as h igher grades are reached), a l though s t a u r o l i t e assemblages can be der ived f rom reac t ions o f the form: c h l + muse = s taur + b io + q tz + H2O as w e l l ( s t a u r o l i t e can e x i s t i n a wider range of composit ion than c h l o r i t o i d ; Hoschek 1967). Regardless o f the 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 the two groups, w i thou t c e r t a i n in te rmed ia te c h l o r i t o i d -s t a u r o l i t e assemblages and/or chemical analyses i t i s d i f f i c u l t t o show which r e a c t i o n i s most l i k e l y represented. Fo r tuna te l y these reac t ions , along w i t h a Page 91 Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia se r i es o f r e l a t e d p e l i t i o reao t ions {Ganguly 1969, Hosohek 1969, Albee 1972} occupy a r e s t r i c t i v e temperature range o f 500 t o 575° C a t pressures o f 4 t o 7 kbars. Some a d d i t i o n a l amount o f u n c e r t a i n t y may be due t o unknown values o f the 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 the t ime these reac t ions would have occurred. An a d d i t i o n a l r e a c t i o n may be suggested by the 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 bear ing u n i t s (F igure 39b shows corroded c h l o r i t o i d i n the presence o f p l a g i o c l a s e ) . According t o the exper imental work o f Hoschek, (1969) the r e a c t i o n : 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 igure 47, below); the assemblage p a i r c td-ab was sa id t o be r e l a t i v e l y r a r e because o f the c lose p rox im i t y o f t h i s 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 the upper reg ions o f the greenschis t f a o i e s . Since p lag ioc lase , and not a l b i t e , i s invo lved w i t h o h l o r i t o i d i t i s be l ieved t h a t a counterpar t s l i d i n g r e a c t i o n t h a t takes the var ious s o l i d s o l u t i o n s i n t o account would have the above r e a c t i o n as one end l i m i t . Basic Type This composit ion t ype i s charac te r i zed by minera ls such as c h l o r i t e , ep idote, a c t i n o l i t e , and hornblende w i t h l e s s than or equal amounts o f f e ldspars and sometimes quar tz ; a l i k e l y parentage would be in te rmed ia te t o basic igneous rocks, maf ic graywackes, and v o l c a n i c l a s t i c sediments. Both the An t le r Formation and the Takla Group rocks f a l l i n t o t h i s composit ion category, though the former i s more basic i n composi t ion; the other u n i t s show only minor Page 92 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Columbia represen ta t ion i n rocks o f t h i s type the most notab le o f whioh i s the qtz-ep-hnbd s c h i s t found i n Domain I I . F igure 45 - Chl-Hnbd-Ep-Qtz Meta-wacke; maf ic minera ls de f ine the S2 f o l i a t i o n i n these and o ther bas ic u n i t s (plane po la r i zed l i g h t , X12.5, L0C-RZ4) The most common assemblage f o r A n t l e r rocks i s hornblende-( a c t i n o l i t e ) - e p i d o t e - c h l o r i t e - p l a g i o c l a s e ( t q u a r t z i c a l c i t e imagne t i t e ) . Takla group rocks, on the o ther hand, show assemblages composed of a c t i n o l i t e - e p i d o t e - c h l o r i t e - a l b i t e ( i q u a r t z i c a l c i t e ) ; occas iona l ly , zoned amphiboles or two amphiboles occur, but one i s most c e r t a i n l y pr imary ( r e l i c t igneous). The Takla Group rocks show a wide range of mesoscopic t e x t u r e s most ly o f primary v o l c a n i c l a s t i c o r i g i n , and superimposed secondary t e x t u r e s are l i m i t e d t o m i l d f o l i a t i o n s , occasional f o l d i n g , and l o c a l i z e d my lon iza t ion . The t y p i c a l assemblage ( a c t - e p - c h l - a b ) occurs as very f i n e growths t h a t bare ly Page 93 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. Br i t ish Coluwbia d i s r u p t many pr imary f e a t u r e s . The growth o f new amphibole ( a c t i n o l i t e ) , ub iqu i tous occurrence of c h l o r i t e , and some ve in ing o f quar tz , ep idote, and/or c a l c i t e represent the ex ten 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 rocks, on the o ther hand, d i sp lay predominately metamorphic e f f e c t s (having l o s t most or a l l pr imary f e a t u r e s ) on both mesoscopic and microscopic scales. The S2 f o l i a t i o n i s formed by c h l o r i t e , amphibole ( a c t i n o l i t e , hornblende, and r a r e l y o ther amphiboles occur ) , and epidote (± f e l s i c s ) (F igure 4 5 ) ; c h l o r i t e has usua l l y grown i n p lanar masses, the amphiboles can occur as random splays or n e a r - p e r f e c t l y a l igned (producing a very good l i n e a r f a b r i c ) w i t h i n p lanar zones, and the ep idote (± f e l s i c s ) forms f i n e t o medium grained g ranob las t i c masses w i t h an o v e r a l l l enso id appearance (F igure 45) . The p r i smat i c nature o f f e l d s p a r (and sometimes quar tz ) i n the more f e l s i c A n t l e r subuni ts a lso a ids i n t he d e f i n i t i o n o f the S2 f o l i a t i o n . The general d i s t r i b u t i o n o f assemblages i n the A n t l e r across the area has been summarized i n F igure 46. Th is map shows a subd i v i s i on o f these assemblages i n t o th ree minera l assemblage popu la t ion groups: 1) a c t i n o l i t e as the only secondary amphibole, 2) a c t i n o l i t e , hornblende, ep idote, and a l b i t e c o e x i s t i n g , and 3) o l i g o c l a s e c o e x i s t i n g w i t h ep idote . Th is breakdown i s based on two genera l ized reac t ions : a l b i t e + ep idote = o l i g o c l a s e + ep idote c h l o r i t e decreasing/hornblende inc reas ing which are a lso shown on F igure 46. The f i r s t r e a c t i o n has been discussed above (see Quar tzo - fe ldspa th ic Type). The second r e a c t i o n has r e c e n t l y been looked a t by Moody e t a l . (1983) w i t h r e l a t i o n t o the t r a n s i t i o n f rom the greenschis t f a c i e s t o the amphibo l i te f a c i e s (compare F igure 37 and F igure 47) . F igure 47 summarizes Page 94 A c t i n o l i t e with no 2ndary Hornblende HornblendTe''''*--'^^ Ili-Gkl-Rk-Cc-HBbi-Otz ^•ds)-Rct-Clz-Cbl-Qtz \ A c t i n o l i t e 5 with no » 2ndary Ep-Jin-Bio-01i|-Chl-Otz <Vtz>-B«sc-li«-Chl-Ep-0lii2 t ofc^ Cc-Qt2-Ep-Chl-ib-H»M Na-Plag with Ep IlzrEp-Para-M-Chl-Bio-HnM-Qtz Ca-Plag"""" (Rspar)-Ps-Talc-Otz-ank . Ep-Iln-CM-Cc-Ctz-OltB <Ep)-lgt-<nasc)-Cfel-(Cc^-Otz-ib Hornblende \ A c t i n o l i t e \ Ca-Plag Hornblende V Qtz-ipt-Ep-Cbi-cc-tb \ with Epidote ^ -4k— Na-Plag \ with E p i d o t e \ \ Cbl-Ep-Otz-Cc-«b Ce-ttl-Ep-ib-HabiVbet ^ \ - _^laba-lb-Ckl-Otz-Ep Cc r lBt-QU-m-Inb--B |Oi L_^. , « ^ _ _ C b l - F e l s i c - E . - i . * 1 l / R c t CBio)-Ep-Hib«-lQt-Oil-Ot2 --^V^^. HBbi-Ctal-Ep-Otz\ SCALE l|t-Cc-Chl-Ep-Hab«/tct-Otz CM-Cc-Otz-li-Ep l|t-Hnbtf/lct-Chl-Ep-Otz-B» k i l o m e t e r s 3T F i g u r e 46 - The d i s t r i b u t i o n o f m a f i c assemblages f o r t h e A n t l e r F o r m a t i o n ; s u r f a c e s shown s e p a r a t e assemblages on e i t h e r s i d e o f two r e a c t i o n s ( h o r n b l e n d e i n and o l i g i o c l a s e i n ) d i s c u s s e d i n t h e t e x t 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 pressure- temperature spaoe; the t r a n s i t i o n zone o u t l i n e d shows the above reac t ions on the low temperature s ide and a second r e a c t i o n : c h l o r i t e out on the h igh temperature s ide . The A n t l e r rocks have c l e a r l y not l e f t t h i s zone (as the c h l o r i t e found across the area i s not a l t e r a t i o n growth) , but must have reached f a r enough t o pass any poss ib le zone o f two c o e x i s t i n g fe ldspa rs . The sur faces o u t l i n e d i n F igure 46 are assumed t o have the same general o r i e n t a t i o n as the major con tac ts ; t h e i r r e p e t i t i o n f rom east t o west would suggest t h a t they form fo lded shapes w i t h e s s e n t i a l l y a D3 f o l d ax is o r i e n t a t i o n . Since the reac t ions associated w i t h these sur faces are, f o r the most p a r t , independent o f pressure the core o f these f o l d e d shapes represents a thermal maximum f o r the M2 metamorphic episode. Temperatures can be expected t o have been i n the range of 500°-575° C a t pressures f rom 4-7 kbars. Calcareous Type Rocks o f t h i s composi t ion may be composed o f c a l c i t e and/or dolomite and/or any combinat ion o f c a l c s i l i c a t e s ( e . g . t a l c , t r e m o l i t e , d iops ide, w o l l l a s t o n i t e ) dependent on the amount o f magnesia and s i l i c a i n the o r i g i n a l rock; s i g n i f i c a n t amounts o f alumina w i l l a l low the minera ls hornblende, ep idote, and p lag ioc lase t o form as w e l l ; i f i r o n i s present the carbonate anke r i t e might form. Usual ly , these rocks are der ived f rom l imestones, s i l i c e o u s l imestones and dolostones, and calcareous and d o l o m i t i c sediments, but some degree of over lap i s unavoidable w i t h calcareous maf ic igneous rocks, as w e l l . Th is type, i n general , i s poor ly represented i n the Crooked Lake u n i t s ; calcareous and a n k e r i t i c r i c h assemblages are present i n the A n t l e r and the p h y l l i t e , whereas bands o f quar tz -musc-ca lc i te occur i n the Snowshoe Formation. Page 96 structural ecology of Part of the Crooked Lake Area, Quesnel Highlands. British Coluwbia 10-, 8. 7 -v. S 6. CO o t CL o CM X 4 -2_ 1 -Sources CHL*PARA-»QTZ=CTD+AB*VAP (CHINNER, [1967],H0SCHEK, [1969]) 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 al, [1983]) I I I I I I I I I I I I 100 200 300 I i I i i i I I I 600 700 800 i I I I I I 400 500 T,° C Figure 47 - Pressure temperature p l o t o f e q u i l i b r i a re levan t t o the 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 maf ic composit ion types Page 97 Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. Bri t ish Colunpla By f a r the most obvious calcareous u n i t s occur i n the Snowshoe fo rmat ion where qtz-musc-cc and zo-plag-musc-cc assemblages occur. I n the Crooked Lake P h y l l i t e and A n t l e r assemblages inc lude musc-qtz-chl -ank, graph-chl-ank-musc-qtz, and less commonly ank-py-ep-cc-ab-qtz . Un fo r tuna te ly , these assemblages are common over most o f the greenschist and i n t o the amphibo l i te f a c i e s so are not p a r t i c u l a r l y d iagnos t i c . F igure 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 general , these u n i t s are g ranob las t i c w i t h a f o l i a t i o n developing only where muscovite or c h l o r i t e i s abundant. The only ins tance of a departure from t h i s pa t te rn occurs i n Domain I 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 the main S2 f o l i a t i o n i n the Snowshoe. I n t h i n sec t ion (F igure 48) , these bands are seen t o cons is t of very f i n e c a l c i t e and minor muscovite and f i n e rounded g ra ins o f quar tz ; Page 98 Structural eeology of Part of the crooked Lake Area, Quesnel Highlands. British Coluwbia next t o these bands the main rock type i s coarse c a l c i t e t h a t shows abundant deformat ion 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 composit ion type i s charac te r i zed by the absence of fe ldspar and occurrence of a n t i g o r i t e , t a l c , a n t h o p h y l l i t e , and other magnesian minera ls ; u l t r a b a s i c igneous rocks are the usual parentage. A serpen t in ized p e r i d o t i t e u n i t was found i n t he A n t l e r Format ion; r e p o r t s o f s i m i l a r u n i t s i n the Snowshoe of t h i s area (R.B. Campbell (1963) and K.V. Campbell (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 the A n t l e r i n t o the Snowshoe. The c h a r a c t e r i s t i c pr imary assemblage o f t h i s u n i t i s opx-o l and secondar i ly serp and cc occur as ex tens ive v e i n i n g across, between, and w i t h i n g ra ins . Serpent ine has developed f rom the pr imary rock as i t grows even along orthopyroxene cleavage planes, but the c a l c i t e has probably been in t roduced from the surrounding 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 igh 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 the metamorphic f ea tu res descr ibed above and those o f the th ree de format iona l events. F igure 49 o u t l i n e s the r e s u l t s o f microscopic examination o f de format iona l f e a t u r e s ; t h i s f i g u r e i s a composite taken from the minera l vs. deformat ion char 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 minera l growth (M1) i s r e s t r i c t e d t o the o ldes t u n i t s and cons is t s o f re fo lded fea tu res and/or f ea tu res t h a t are e a r l i e r than the D2 deformat ion. Unfor tuna te ly , a p o s i t i v e connect ion 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 igure 49 f o r many of the minerals t h a t may represent D1 f e a t u r e s Page 99 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia Figure 49 - Summary o f m inera l growth r e l a t i v e t o deformat ion fea tu res composed f rom diagrams o f i n d i v i d u a l samples and t h i n sec t ions descr ibed i n Page 100 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia t ransposed p a r a l l e l S2 i n the lower two u n i t s . The D2 episode corresponds w i t h the g rea tes t amount o f minera l growth i n a l l u n i t s ( the M2 event) and thus represents a cu lmina t ion i n the metamorphic h i s t o r y o f the area. A smal 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 the t h i r d event (M3) t o the D3 deformat ion. Evidence f o r the M1 event c o n s i s t s o f r e fo lded b i o t i t e f o l i a t i o n s and h igh angle i n c l u s i o n s w i t h i n K- fe ldspar . Both o f these minera ls are common associates o f amphibo l i te 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 h igh l e v e l o f temperature and pressure the two lowest u n i t s should have been ex tens ive ly a f f e c t e d . A s t rong and endur ing h i s t o r y f o r the 02 episode i s be l ieved, by the present author, t o account f o r the 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 ea tu res . Some degree o f u n c e r t a i n t y about the he igh t reached by t h i s event e x i s t s because K-f e ldspar may equa l ly or more l i k e l y be a pr imary phase. A c lea r 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 o f the H2 event. Extensive minera l growth i n a l l u n i t s has l a r g e l y masked o r i g i n a l f ea tu res causing the development o f very dominant secondary f a b r i c s . Minera l e q u i l i b r i a f rom two of the f i v e composi t ion groups have al lowed maximum temperatures t o be est imated and the l a t e s t e x i s t i n g temperature g rad ien t f i e l d s t o be understood; temperatures o f 500° -575° C a t pressures f rom 4-7 kbars were der ived f rom c h l o r i t o i d e q u i l i b r i a , and the t r a n s i t i o n s f rom a o t i n o l i t e t o hornblende assemblages and from a l b i t e - epidote 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 sur faces associated w i t h the 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 rad ien ts increase toward the southeast ; t h e i r f o l d e d form most l i k e l y developed a f t e r the 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 * w T O T ss s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s w s s s s s ss s s s s s s s s s s s s s s s s s s s s s s s s s s \\\\\\\ S S S S S S S S S S S S S S s s s s s s s S S S S S S S s s s s s s s sssssss S S S S S S S ' S S S S S S S ' S S S S S S S \ \ \ \ \ \ \ S S S S S S S S S S S S S S s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s w w w w w w ' " W W W W .WW W W s s s s .WW .WW .WW sssss ssss W W W W ssss A S S l W W .WW .WW w w w .www ss s s s s s s s s s s s s s s s s s s s S S S S S S S sssssss w w w \ ssss s s s s s s s s s s w w w \ w w \ w w w w s w w w s L s s s s W W .WW W W - w\ sss Sioislne >f\SSSS •>ww ssss s w w ww w w \ w w w s ssss s s s s s s s s s s w s s s w s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s - s s s s s s s s s s s s s s s s s s s v / / / / / / / / ss / / / / ss s s s \ \ / / / / / / / / \ s s s s / / / / ss s s s . ss / / / / X f X t t f f f S f * / HUM. arsca l ira METAMORPHISM Figure 50 -c NESEIT III CMFianiTIM c I J IS I r l t t l e Event (S5 Fractariei, f u l t i e i ) c ctanei, l B4 FtMii J r n i i — (S4 FricUre Cletviie) c I 13 Fallini (S3 Spicei Cleiviie) c I 12 Faltfiii/Tkmtiai (S2 Preiiieit Faliatiea/aeavaie) - ~ i I 3 Takla Creep Cretkel Lake Pkillite Eireki Qaartzlte f II Fa l l l i i \ V<SI Fallttloa) J I ••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 deformat ion 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 the absolute t ime sca le ; metamorphic scale shows t h r e e genera l ized grades: b u r i a l , greenschis t , amphibo l i te Page 102 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Pressure est imates are r a t h e r wide, compared t o those of temperature, but no s u i t a b l e reac t ions t o determine pressure were observed. I t may be assumed based on previous f i n d i n g s i n the reg ion (K. V. Campbell 1971, F le tche r 1972) t h a t a t y p i c a l Barrov ian 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 (pressure o f about 4 kbars ) ; the minera l assemblages represented would be associated w i t h t h i s type o f 'P -T ' t r a j e c t o r y . F igure 50 shows a summary o f the metamorphic/deformat ional r e l a t i o n s h i p s deduoed. I n t h i s diagram r e l a t i v e t i m i n g o f the 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 ime (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 is to r ies(shown as the wid th o f bar graphs f rom l e f t - h a n d s i d e ) . The Snowshoe i s shown as a separate package exper ienc ing b u r i a l metamorphism before the t ime of A n t l e r emplacement, not on the bas is o f evidence t o the e f f e c t but s imply t o i l l u s t r a t e t h a t the o r i g i n o f the two u n i t s were d i s t i n c t f rom one another; f o l l o w i n g t h a t t ime these two u n i t s are shown j o ined and toge ther experienced the M1 episode wh i le 01 f o l d i n g took p lace. These u n i t s remain bu r ied wh i le the upper u n i t s were emplaced and from t h a t p o i n t onward t h e i r common h i s t o r y shows two f i n a l metamorphic/ deformat ional episodes fo l l owed by two l a r g e l y de format iona l events. Page 103 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 the boundary between two d i s t i n c t geotectonic provinces o f the Canadian C o r d i l l e r a t h a t have shared a common h i s t o r y a t l e a s t s ince the mid Jurass ic . The b e l t s t o the east o r i g i n a t e d as a p l a t f o r m a l sequence o f f t he coast o f the North American c ra ton from Pro te rozo ic t o e a r l y Phanerozoic t ime . To the west t he te r ranes show evidence o f a mid-Phanerozoic o r i g i n i n an oceanic s e t t i n g . The two regions could e a s i l y have developed thousands o f k i l omete rs f rom each o ther . The 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 invo lved rocks o f the Kaza Group, l o c a l p l a t f o r m a l represen ta t i ves , and a u n i t , the A n t l e r Formation, t h a t i s be l ieved t o be a sec t ion o f ocean c r u s t (Campbell, 1971; Montgomery, 1978). T h r u s t i n g o f the A n t l e r over the Kaza caused m y l o n i t i c t e x t u r e s t o form a t t he con tac t between the u n i t s ; the e a r l y phase o f f o l d i n g recorded i n both rock types could have accompanied t h i s t h r u s t i n g episode, though i t i s a lso poss ib le t h a t these fea tu res record events t h a t pre-date t h r u s t i n g , thus being unique t o the i n d i v i d u a l u n i t s . The remaining u n i t s were in t roduced i n t o the area perhaps by t h r u s t i n g , as w e l l ; t h i s i n t e r p r e t a t i o n seems more reasonable than simple depos i t ion because of the poss ib le a l lochthonous assoc ia t i on these upper u n i t s have w i t h t e r rane rocks t o the west. Th rus t i ng would exp la in t r u n c a t i o n o f the Eureka Q u a r t z i t e as w e l l as the s t rong my lon i te development a t the top o f the p h y l l i t e . The age of the 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 of the reg iona l p i c t u r e . Consider ing the abundance o f s l a t y rock types i n the Omineca b e l t t o the no r th and nor theas t , i t i s understandable t h a t e a r l y workers l i n k e d the p h y l l i t e s w i t h these rocks (Campbell and Tipper, 1971). The present author. Page 104 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 the 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 the Crooked Lake P h y l l i t e and u n i t s such as the Paleozoic Black S t u a r t Formation as descr ibed by S t r u i k , (1981). Such c o r r e l a t i o n s , though, oppose the f o s s i l c o l l e c t i o n s known t o date t h a t suggest an upper T r i a s s i c age. I t i s be l ieved t h a t the Crooked Lake p h y l l i t e w i t h i t s occas ional l imy hor izons and good h igh e l e v a t i o n exposures w i l l one day y i e l d the f o s s i l s t o date t h i s u n i t . The f l e x u r a l f o l d i n g recorded i n the p h y l l i t e could be r e l a t e d t o an emplacement process and seems t o have occurred whi le the m a t e r i a l was s t i l l wet. The con t inu ing deformat ion oo inc ided w i t h an increase o f metamorphic grade ( t h a t probably fo l lowed a Bar rov ian t r a j e c t o r y t o the boundary between the greenschis t and amphibo l i te metamorphic f a c i e s ) ; i n t u r n , a t p rogress ive ly h igher and h igher temperatures the response o f t he rock u n i t s changed so t h a t f o l d s became more c h a r a c t e r i s t i c a l l y s i m i l a r i n s t y l e . Abundant shear ing o f the u n i t s took place along p rev ious ly formed a x i a l p lanar f a b r i c s t o accommodate the s t r a i n w i t h i n the rock mass. The next phase saw the onset o f deformat ion forming wester ly verg ing f o l d s . By t h i s t ime, metamorphic grade had decreased and accord ing ly f o l d s had changed t o a more f l e x u r a l s t y l e . The c o p l a n a r i t y (and c o l i n e a r i t y ) o f t h i s event ( w . r . t . the prev ious events) has made separat ion o f these f o l d s f rom e a r l i e r minor f o l d forms d i f f i c u l t or impossib le i n o e r t a i n areas ( i . e . Domain I , southwest o f Crooked Lake) ; i t i s be l ieved t h a t much of the s t r a i n energy invo lved i n t h i s phase would be used t o t i g h t e n e x i s t i n g forms ra the r than create new ones. Page 105 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia The 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 ransverse t o the previous ones represents a s i g n i f i c a n t departure from the type o f mechanism opera t ing i n the reg ion up t o t h i s t ime. Subsequently, b r i t t l e deformat ion ( f r a c t u r i n g and f a u l t i n g ) w i t h a poss ib le 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 the Crooked Lake u n i t s . The l a t e r h i s t o r y o f the area, as evidenced f rom nearby reg ions, inc lude the 100 Ma i n t r u s i v e s o f Campbell and T ipper , (1970), Eocene vo lcan ic a c t i v i t y , Miocene t o Pl iocene p la teau basa l t s , and most r e c e n t l y an extended per iod o f c y c l i c a l g l a c i a l a o t i v i t y (T ipper , 1971). Page 106 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia LIST OF REFERENCES CITED Albee, A . L . , 1965. A pet rogen ic g r i d f o r the Fe-hg s i l i c a t e s o f P e l i t i c Sch is ts . Am. J . S c i . , v.263, p.512-536. Albee, A.L. ,1972. Metamorphism o f P e l i t i c Sch is ts : Reaction Re la t ions o f  C h l o r i t o i d and S t a u r o l i t e . Geol. Soc. America B u l l . , v. 83, p. 3249-3268. Anderson, E.M.,1951. The Dynamics o f F a u l t i n g . O l i v e r and Boyd, Edinburgh, 206pp. Berry, M.J.and D.A. Forsy th , 1975. S t r u c t u r e o f the Canadian C o r d i l l e r a f rom  Seismic R e f r a c t i o n and Other Data. Can. J . Ear th S c i . , v. 12, p. 182-208. Bowman, A., 1889. The Geology o f the Mining D i s t r i c t o f Cariboo, B r i t i s h Columbia. Wm. F. Annual Rept. 1887. Brown, R.L. and P.B. Read, 1983. Shuswap Terrane of B r i t i s h Columbia: A Mesozoic  "core complex''. Geology, v. 11, p. 164-168. Campbell, K.V., 1971. Metamorphic Pet ro logy and S t r u c t u r a l Geology o f the Crooked  Lake Area, Cariboo Mountains, B r i t i s h Columbia, unpublished PhD Thesis, U n i v e r s i t y o f Washington. Campbell, R.B., 1963. Quesnel Lake (east h a l f ) B r i t i s h Columbia. Geol. Surv. Can., Map 1-1963. Campbell, R.B., 1978. Quesnel Lake, B r i t i s h Columbia. Geol. Surv. Can., Open F i l e Map 574. 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P e t r . , v .22, p.208-232. Johnson, W.A. and W. L. Uglow, 1926. Placer and Vein Gold Deposi ts o f B a r k e r v i l l e ,  Cariboo D i s t r i c t , B r i t i s h Columbia. Geol. Surv. Can. Mem. 149, 246p. Jones, D.L. , D.G. Howel l , P.J. Coney, and J.W.H. Monger, 1983. Recogni t ion,  Character, and Ana lys is o f Tec tonos t ra t i g raph i c Terranes i n Western North  America, i n M. Hashimoto and S. Uyeda (eds . ) Aooret ion Tectonics i n the Circum-Pacif i c Regions, Terra S c i . Pub. Co., Tokyo. K e r r i c k , D.M., 1972. Exper imental de terminat ion o f the muscovite + quar tz  s t a b i l i t y w i t h Pn?n < Ptntai. Am. J . S c i . , v.272, p.946-958. Marshal, 1927. Clearwater Lake Map Area, i n Geol. Surv. Can., Sum. Rept. 1927, Par 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 the c r u s t and  upper mantle under the h ighest ranges o f the Canadian Rockies f rom a seismic  r e f r a c t i o n survey. Can. J . Ear th S c i . , v. 14, p. 196-208. Miyashi ro, A. , 1973. Metamorphism and metamorphic b e l t s . John Wiley & Sons, New York, 492p. Moody, J . B . , D. Meyer, and J.E. Jenkins, 1983. Experimental c h a r a c t e r i z a t i o n o f  the g reensch is t /amph ibo l i t e boundary i n maf ic systems. Am. J. S c i . , v.283, p.48-92. Monger, J . W. H., 1977. Upper Paleozoic rocks of the Western Canadian C o r d i l l e r a and  t h e i r bear ing on C o r d i l l e r a n e v o l u t i o n . Can. J. Ear th S c i . , v. 14, p.1832-1859. Page 109 structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Columbia Monger, J . W.H. and W. W. Hutohinson, 1971. Metamorphio map of 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 ce , and D. J. Tempelman-Kluit, 1982. Tectonic acc re t ion and  the o r i g i n o f the two major metamorphic and P lu ton i c we l ts i n the Canadian  C o r d i l l e r a . Geology, v. 10, p. 70-75. Montgomery, S .L . , 1978. S t r u c t u r a l and metamorphic h i s t o r y o f the Lake Dunf ord map  area. Cariboo Mountains, B r i t i s h Columbia: O p h i o l i t e obduct ion i n the  southeastern Canadian C o r d i l l e r a , unpubl ished MSc t h e s i s , Co rne l l U n i v e r s i t y , 170p. Murphy, D.C., and J.M. Journeay, 1982. S t r u c t u r a l s t y l e i n the Premier Range,  Cariboo Mountains, southern B r i t i s h Columbia: P re l im inary Resul ts , i n Current Research, Par t A, Geol. Surv. Can., Paper 82-1 A, p.289-292. Murphy, D.C., and C. J . Rees, 1983. 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 the  Cariboo Mountains, B r i t i s h Columbia, i n Current Research, Par 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 he Shuswap Metamorphic Complex i n C o r d i l l e r a n  tecton ism: a review. Can J . Ear th S c i . , v . 2 1 , p. 1171-1193. P e l l , J . and P.S. Simony, 1982. Hadrynian Horse th ie f Creek Group c o r r e l a t i o n s i n  the Southern Cariboo Mountains, B r i t i s h Columbia, i n Current Research, Par t A, Geol. Surv. Can., Paper 82-1 A, p.305-308. Pe t t i John , F . J . , P.E. P o t t e r , and R. Siever , 1972. Sand and Sandstone. Spr inger -Ver lag, New York, 622p. Pigage, L.C., 1977. Rb-Sr dates f o r g r a n o d i o r i t e i n t r u s i o n s on the nor theast  margin o f the Shuswap Metamorphic Complex, Cariboo Mountains, B r i t i s h  Columbia. Can J. Ear th S c i . , v .14, p. 1690-1695. Ramsay, J. G., 1967. Fo ld ing and F r a c t u r i n g o f Rocks. McGraw-Hil l , New York, 568p. Rees, C . J . , 1981. Western margin o f the Omineca B e l t a t Quesnel Lake, B r i t i s h  Columbia, i n Current Research, Par t A, Geol. Surv. Can., Paper 81-1A, p.223-226. Rees, C. J . , and F. F e r r i , 1983. A k inemat ic study o f m y l o n i t i c rooks i n the  Omineca-Intermontane B e l t t e c t o n i c boundary i n e a s t - c e n t r a l B r i t i s h Page 110 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Columbia, i n Current Research, Par 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 the Okanagan Va l ley , B r i t i s h Columbia. Can. J . Ear th S c i . , v. 18, p. 1581-1598. Spry, A. , 1969. Hetamorphio t e x t u r e s . Pergammon Press, Oxford, 352p. S t r u i k , L.C., 1981. Snowshoe Formation, c e n t r a l B r i t i s h Columbia, i n Current Research, par t -A , Geol. Surv. Can., Paper 81-1 A, p.213-216. S t r u i k , L.C., 1981. A re-examinat ion o f the type area o f the Oevono-Hississ ip ian Cariboo Orogeny, c e n t r a l B r i t i s h Columbia. Can. J . Ear th S c i . , v. 18, p.1767-1775. S t r u i k , L.C., 1982. Snowshoe Formation (1982), c e n t r a l B r i t i s h Columbia, i n Current Research, p a r t - B , Geol. Surv. Can., Paper 82-1B, p. 117-124. Suther land Brown, A., 1957. Geology o f the 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. Suther land Brown, A. , 1963 Geology o f the Cariboo River 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. 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 . Ear th S c i . , v .8 , p.743-752. Tipper, H.W., R.B. Campbell, G.C. Tay lo r , and D.F. S t o t t , 1979. Parsnip River , B r i t i s h Columbia (Sheet 93) . Geol. Surv. Can., Map 1424A (1 :1 ,000,000) . Travers, W.B., 1978. Overturned N i c o l a and Ashcro 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. Ear th S c i . , v. 15, p.99-116. Turner, F . J . , 1981. Metamorphic pe t ro logy : Minera log ic , f i e l d , and t e c t o n i c aspects. McGraw-Hi l l , New York, 526p. Uglow, W.L., 1922. Geology o f t he Nor th Thompson v a l l e y map area, B r i t i s h Columbia. Geol. Surv. Can., Sum. Rept. 1921, Par t A, p.76-106. Wheeler, J .O. , 1967. Tectonics i n Canadian Upper Mantle Report, G. S.C. Paper 67-41, p.4-30. Wheeler, J .O. , 1970. Summary and Discussion, S t r u c t u r e o f the Southern Canadian  C o r d i l l e r a . G.A.C. Sp. Paper #6. Page 111 Structural fienlow of Part at th» Crinilwri l a l t P * T »a Qiipgnpl HiflhlaniU, B r i t i sh finliwhia APPENDIX A This sec t ion summarizes rock d e s c r i p t i o n data f o r t he f i v e u n i t s a t Crooked Lake. Host of the i n f o r m a t i o n presented i s f rom extens ive microscopic examination o f t h i n sect ions cut f rom samples taken i n the f i e l d and a few d e s c r i p t i o n s are taken from m ine ra log i ca l and t e x t u r a l data recorded i n the f i e l d . The f o l l o w i n g format was used e x c l u s i v e l y : Colour Grain Size Mineralogy Texture Assemblages Name H i s t o r y Weathered and f r e s h sur faces were examined The standard used was the one commonly used f o r sandstones taken f rom P e t t i j o h n e t a l , (1972)- 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 sec t i on were made by comparing g ra ins t o known f i e l d - o f - v i e w diameters. Est imat ions were made i n the f i e l d . Eva lua t ion o f minera l percentages i s based on two or more t h i n sec t ions (where poss ib le ) cu t a t 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 the whole volume of rock i s considered. Ranges given attempt t o account f o r the f i n e scaled heterogenei ty o f t e n encountered (banding, ve in ing , v a r i a b l e s o r t i n g ) . F i r s t , the o v e r a l l t e x t u r e o f the rock i s descr ibed, fo l l owed by important microscopic f e a t u r e s o f c o n s t i t u e n t minera ls . Coex is t ing phases are given f o r the rock A name i s g iven t o the rock I n the case of most o f the data a r e l a t i v e da t i ng diagram has been const ructed assoc ia t i ng growth o f minera ls w i t h mesocopic def ormat iona l elements The u n i t s descr ibed i n t h i s appendix c o r r e l a t e exac t l y t o those shown on P la te 4, the S t r u c t u r a l / S t r a t i g r a p h i c Sect ions; the order used here i s , f i r s t , 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 , e t c . ) and, second, r e l a t i v e t o i nc reas ing s e c t i o n number (e. g. Snowshoe has representa t i ves i n Sect ions 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 Size Mineralogy Textures Assemblages Name weathered - yel low-brown t o t a n f r e s h - t a n t o grey-green f i n e t o medium w i t h coarse b i o t i t e andgarnet, coarse quar tz ve in ing 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 60-90* Accessory Muscovite 15-08% Garnet C h l o r i t e 20-00% Tourmaline B i o t i t e / F e Oxide 05-02% F i n e l y laminated t o f i n e l y layered (mm- dm s c a l e ) ; composi t iona l l a y e r i n g o f 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 genera l l y d iscont inuous; my lon i te banding a lso | | S2 f o l i a t i o n . S2 f o l i a t i o n ranges f rom a spaced cleavage i n f e l s i c subuni ts t o a pene t ra t i ve f o l i a t i o n i n p e l i t i c subuni ts and has been crenu la ted by a t l e a s t one l a t e r cleavage. Wavy and undu la t ing form. Packages show medium t o t i g h t f o l d i n g Micas - d imens iona l -p re fe r red o r i e n t a t i o n de f ines S2 f o l i a t i o n and poss ib le e a r l i e r f a b r i c ( s ) Chl-Musc-Qtz Bio-Musc-Chl-Qtz Musc-Qtz Bio-Chl-Musc-Qtz Sch is t D1 D2 Qtz Muse Bio Chl Augen Feld Mylonit ic Banding U n i t s A 1 a . A 1 b . A 1 c ' Page 113 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia [A2a] {RZ8, RZ11} Colour weathered - dark yel low-brown t o yel low-orange f r e s h - rus ty , l i g h t grey t o whi te Grain 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 a t g r a i n boundries - ve ry 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 C a l c i t e 90-95% Muscovite 08-05% Quartz 02-00% Textures Medium layered 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 ze banding (mm t o cm sca le ) i s | | S2 f o l i a t i o n and d iscont inuous C a l c i t e - shows e a r l y deformat ion tw inn ing and l a t e k i n k i n g ; e longat ion c r y s t a l s 11 S2 f o l i a t i o n ; l a rge 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 form and bent c r y s t a l s ; s t rong l a t t i c e - p r e f e r r e d and d imens iona l -p re fe r red 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 Quartz - undeformed, rounded medium s ized g ra ins as i n c l u s i o n s or i n f i n e mat r i x Assemblage Qtz-Musc-Calc i te Name Qtz-Musc-Calc i te 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, Colour RZ10,RZ11} Grain Size Mineralogy Textures weathered - r u s t y brown t o tan f r e s h - tan t o pale o l i v e f i n e t o coarse w i t h i n te r l am ina ted 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- fe ldspar p o r p h y r o - b l a s t s / c l a s t s Quartz 67-89* Accessory B i o t i t e 12-05% Garnet Muscovite 08-03% I l m e n i t e C h l o r i t e 03-00% Ctd,Apat K- fe ldspar 05-02% Sphene P lag ioc lase (An24) . . . 03-01% F i n e l y laminated t o f i n e l y layered ; composi t iona l l a y e r i n g and my lon i te banding | S2 f o l i a t i o n and genera l l y d iscont inuous; S2 f o l i a t i o n ranges f rom 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 associated 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 renu la ted by a t l e a s t one l a t e r cleavage, f e l d s p a r e longat ion 11 one o f these l a t e c r e n u l a t i o n s Quartz - common undulatory e x t i n c t i o n and i n t e r n a l g r a i n s u b d i v i s i o n ; f i n e m a t e r i a l a long g r a i n boundr ies; boundries s t r a i g h t t o curved, sometimes se r ra ted and hazy Micas - genera l l y grow e p i t a x i a l l y ; d imens iona l -p re fe r red o r i e n t a t i o n de f ines S2 Page 115 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Assemblages Name [A3a] {J112, Colour J113, J114} Grain Size Mineralogy Textures Assemblages Name Qtz Muse Bio 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 f e l d s p a r - f i n e m a t e r i a l i n c l u s i o n t r a i l s have S i * S e Ol ig -Ch l -K fe ldspar-Muso-Bio-Qtz Musc-Bio-Qtz Musc-Bio Q u a r t z i t e and K f e l d s p a r augen Ol ig-Chl -Musc-Bio-Qtz Sch is t weathered - whi te t o r u s t y brown f r e s h - t a n t o b lue grey medium w i t h coarse b i o t i t e porphyroblasts Quartz /Feldspar 90-95% Muscovite 05-03% B i o t i t e 05-02% Coarsely layered ( > m scale ) ; composi t ional 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 Micas - d imen t iona l -p re fe r red 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 Bio-Musc-Qtz-Feldspar Bio-Musc Q u a r t z i t e and Bio-Musc-Qtz-Feldspar Sch is t pre D2 post Units A3a, A3b [A1c] {J76} 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} [ A i d ] {J107} Mineralogy Quartz 65-89% Muscovite 20-05% B i o t i t e 10-05% P lag ioc lase (An26) . . . 05-01% Textures F i n e l y laminated t o f i n e l y layered ; composi t iona l l a y e r i n g i s t i g h t l y f o lded 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 nvo l ved i n u p r i g h t open t o medium f o l d forms Assemblages Ol ig-Bio-Musc-Qtz Musc-Qtz Name Bio-Musc-Qtz-Ol ig Sch is t and minor Muse Q u a r t z i t e Colour weathered - pale yel low brown f r e s h - medium blue grey Grain Size medium w i t h coarse garnet porphyroblasts Mineralogy Quartz 90% B i o t i t e 05% Muscovite 02% Garnet porphyroblasts . .03% Textures Massive w i t h very s t rong 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 imensional ly 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 la tes 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 (web- l i ke ) t o i d i o b l a s t i c ; conta ins random i n c l u s i o n s Assemblage Musc-Gn-Bio-Qtz Name B io Q u a r t z i t e Colour weathered - whi te t o r u s t y brown f r e s h - r u s t t a n t o grey Grain 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 50% Accessory Plagioc lase(An22) 28% Garnet Musoovite 15% C h l o r i t o i d B i o t i t e 05% Page 117 Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia Textures Assemblages Name Ilmenite 02* Coarsely laye red ; composi t ional 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 genera l l y d iscont inuous; S2 f o l i a t i o n i s w e l l developed throughout ; S2 f o l i a t i o n i s c renu la ted by a spaced cleavage Micas - grow e p i t a x i a l l y ; d imensional -p r e f e r r e d o r i e n t a t i o n def ines S2 f o l i a t i o n and poss ib le e a r l i e r f a b r i c (occur a t h igh angle t o and are cu t by S2 f o l i a t i o n ) ; occassional g ra ins cross cu t f o l i a t i o n F e l s i c s - show m i l d undulatory ext inct ions-s t r a i g h t t o curved g r a i n boundries I lm-B io-Musc-Dl ig -Qtz Bio-Musc-Qtz Bio-Musc-Ol ig-Qtz Sch is t and Bio-Musc Q u a r t z i t e Qtz Plag Muse Bio Gn D2 D3 Units A i d , A le [A2b] {J74} Colour Grain Size Mineralogy weathered - t a n t o r u s t brown f r e s h - t a n t o b lue grey medium C a l c i t e 85-05% Muscovite 10-20% Quartz 05-40% Plag ioc lase(An90) . . .00-30% B i o t i t e 00-05% Accessory Sphene Textures F ine t o medium layered ; on f i n e t o medium scale composi t iona 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 iscont inuous t o vaguely Page 118 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British colunbia [A4a] {J75} gne iss io 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 scale marble occurs as i s o c l i n a l l y f o lded 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 undu la t ing form and i s c renu la ted by a t l e a s t one l a t e r cleavages Assemblages Qtz-Felds-Musc-Cc Bio-Musc-Qtz Name Qtz-An-Musc-Cc Marble, Muse Quar t z i t e , and Bio-Musc-Qtz Sch is t Colour weathered - greenish grey f r e s h - l i g h t grey t o dark grey Grain 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% Spine l Textures F i n e l y laminated t o f i n e l y layered ; oomposi t ional l a y e r i n g of hornb lende- r ioh and e p i d o t e - r i c h subuni ts i s d iscont inuous t o gne iss io (poss ib l y of metamorphic o r i g i n ) and invo lved i n r o o t l e s s i n t r a f o l i a l i s o c l i n e s ; S2 f o l i a t i o n i s pervasive throughout Hornblende - some high angle g ra ins cut by f o l i a t i o n may represent e a r l y formed f a b r i c ; s t r o n g l y de f ines 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 g ra ins 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 deformat ion bands and s t rong undu la tory 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 Sch is t Page 119 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluitbla pre D2 post Qtz I - — j Hnbd — j j EP | — j Sphene I j Rutile j Unit A4 [ A l e ] {J73, J72} Colour weathered - r u s t brown t o red brown f r e s h - red brown t o dark grey Grain Size medium t o coarse Mineralogy Quartz 05-75* Muscovite 70-05* B i o t i t e 10-10* P lag ioc lase (An36) . . . 10-05% Garnet 00-05% Textures F i n e l y laminated t o f i n e l y layered ; composi t iona 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 d iscont inuous t o gne iss i c and invo lved i n r o o t l e s s i n t r a f o l i a l i s o c l i n e s Assemblage Gn-Ands-Bio-Musc-Qtz Name Gn-Ands-Bio-Musc-Qtz Sch is t Page 120 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia ANTLER FORMATION [B1a] {RZ1, Colour weathered - r u s t y brown t o l i g h t green RZ1} f r e s h - b lue green t o l i g h t green Grain Size very f i n e w i t h f i n e t o medium c h l , b io , hnbd, mgt Mineralogy Quartz 40-88* A l b i t e 35-00* C h l o r i t e 10-03* B i o t i t e 05-00* Hornblende 05-03* Magnet i te 00-04* Epidote 0 3 - 0 1 * C a l c i t e 0 2 - 0 1 * Textures F i n e l y laminated; composi t ional l a y e r i n g o f c h l - q t z s c h i s t and ep-hnbd-chl meta- wacke d iscont inuous 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 rom a pene t ra t i ve f a b r i c i n maf ic 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 renu la ted by one l a t e r cleavage F e l s i c s - show c l a s t i c or poss ib ly c a t a c l a s t i c t e x t u r e Micas - d imens iona l -pre fered 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 Hornblende - g ra ins found t o l i e a t h igh angle t o S2 f o l i a t i o n c ross -cu t c h l o r i t e g ra ins ; 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 Sch is t , Hnbd-Chl-Mgt-Qtz Sch is 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 id [B2a] {RZ1, RZ1, RZ3} Colour weathered - tan t o r u s t y brown f r e s h - b lue green t o dark green Grain Size very f i n e w i t h f i n e t o medium hnbd, b io Mineralogy Quartz 03-10* A l b i t e 40-20% C h l o r i t e 10-05% Epidote 10-35% Bornblende . . 30-00% i o t i t e (oxy-verm?). 00-20% C a l c i t e 05-10% Magnet i te 02-00% Textures F i n e l y laminated; composi t ional l a y e r i n g o f ep idote 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 poss ib le 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 ve ins, lenso ids , and spheroids show an arrangement | I t o compos i t iona 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 l i t h o l o g y Hornblende - g ra ins grow across g ra ins 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 - d imens iona l -p re fe r red 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 B i o t i t e - some gra ins l i e a t h igh angle t o and are cu t by o ther g ra ins t h a t o u t l i n e / d e f i n e S2 f o l i a t i o n Page 122 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia Magnet i te - g ra ins have quar tz pressure shadows a l igned 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 Sch is t and Cc-Qtz-Bio-Ab-Ep meta-wacke Qtz Ab Hnbd Bio Chl Mgt Ep-Cc veins 02 post Unit B2a [B3a] {RZ3, RZ4} Colour Grain Size Mineralogy Textures weathered - t a n t o r u s t y brown t o whi te green f r e s h - dark green t o p i s t a c h i o green very f i n e t o f i n e Quartz 42-40% Accessory Epidote 35-30% B i o t i t e C h l o r i t e 05-25% Hornblende 05-04% Magnet i te 05-00% C a l c i t e 02-01% A l b i t e 05-00% F i n e l y laminated t o f i n e l y layered ; composi t iona l l a y e r i n g ranges from f a i r l y cont inuous t o d iscont inuous becoming l e n s e - l i k e and sphero ida l and i s most ly | | t o S2 f o l i a t i o n ; f o l i a t i o n i s pene t ra t i ve i n c h l o r i t e r i c h u n i t s , o therwise i s best o u t l i n e d by f e l s i c - c c - e p lenso id /sphero ids ; S2 f o l i a t i o n has been crenu la ted by two l a t e r cleavages C h l o r i t e - d imens iona l -p re fer red o r i e n t a t i o n de f ines S2 f o l i a t i o n Page 123 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Hornblende - some gra ins 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 lea r ( a c t i n o l i t i c ) i n t e r i o r s t o p leochro ic (hornb lend ic ) r ims C a l c i t e - g ra ins show h igh degree of tw inn ing Assemblages Ab-Cc-Mgt-Hnbd-Qtz-Chl-Ep Ab-Cc-Qtz-Hnbd-Chl-Ep Name Ab-Hnbd-Chl-Ep-Qtz Sch is t and Ab-Hnbd-Chl-Ep-Qtz m e t a - l i t h i c wacke Qtz Ab Act Chl Mgt Ep-Cc veins pre 02 post 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 A l b i t e 45% Quartz 35% Hornblende 10% C h l o r i t e 05% Epidote 03% Hagnet i te 02% Textures Hassive t o f i n e l y layered ; S2 f o l i a t i o n d i s t i n c t on ly where h o r n b l e n d e / c h l o r i t e are abundant, o therwise i s represented by a conjugate spaced cleavage Hornb lende/Ch lor i te - d imensional - p re fe r red o r i e n t a t i o n de f ines 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 composi t ional l a y e r i n g Page 124 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia [B4a] {RZ4} Assemblage Name Colour B ra in Size Mineralogy Textures Assemblage Name 01 En Serp Cc Mgt-Ep-Chl-Hnbd-Qtz-Ab Hnbd-Qtz-Ab Meta-wacke and Ep-Chl-Qtz-Ab Meta-wacke weathered - orange brown f r e s h - medium b l u i s h - g r e y t o greenish-grey very coarse w i t h f i n e serpent ine along f r a c t u r e s O l i v i n e 40* Orthopyroxene 35* C r y s o t i l e 20* C a l c i t e 05* Massive and h i g h l y f r a c t u r e d Serpent ine - 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???) Ol iv ine/Or thopyroxene - assumed t o represent o r i g i n a l makeup of rock, now i s seen as smal l peices o f g ra ins f l o a t i n g on a background of se rpen t ine ; many adjacent g ra ins are o p t i c a l l y co inc iden t C a l c i t e - occurs w i t h serpent ine and a lso i n l a r g e r scaled ve ins Cc-Serp-0px-01 Serpent in ized p e r i d o t i t e Unit B4a [ B i c j {RZ5} Colour weathered - greenish-grey t o l i g h t grey f r e s h - b l u i s h - g r e y t o t a n Grain 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 45-10% Epidote 25-30% C h l o r i t e . 20-05% Hornblende 05-50% Magnet i te 05-00% A l b i t e 00-05% Textures F i n e l y laminated t o f i n e l y layered ; composi t iona l l a y e r i n g o f chl -hnbd and e p - f e l s i c u n i t s ranges f rom f a i r l y cont inuous t o d iscont inuous becoming l e n s o i d t o spheroid ( p a r t i c u l a r i l y the 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 ch l /hnbd 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 associated 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 dest roy the shor t l imb Hornblende - most g ra ins show d imens iona l -p re fe r red o r i e n t a t i o n t h a t de f ines the S2 f o l i a t i o n ; some gra ins l i e a t h igh angle t o and are c ross -cu t by S2 f o l i a t i o n g ra ins C h l o r i t e - d imens iona l -p re fe r red 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 Assemblages Epidote - g ra ins commonly form l e n s o i d a l masses | | t o S2 f o l i a t i o n Chl-Ep-Qtz Ab-Chl-Qtz-Ep-Hnbd Name Chl-Ep-Qtz Meta-wacke Ab-Chl-Qtz-Ep-Hnbd Sch is t Qtz Ab Hnbd Chl Mgt Ep-Cc veins pre D2 post Unit B1c [B5a] Page 126 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia {V5b} Colour Grain Size Mineralogy Textures Assemblage Name Qtz Ab Hnbd Ep Cc Chl Mgt weathered - t a n t o o l i v e grey f r e s h - wh i te t o medium greenish grey 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* Fine t o medium layered ; composi t ional 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 invo lved 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 splays ooour i n p lanar zones o u t l i n i n g S2 f o l i a t i o n Epidote - occurs as l enso id /sphero id bodies t h a t o u t l i n e f o l i a t i o n ; more concentrated toward the top F e l s i c s - commonly incuded w i t h hornblende porphyrob las ts Ep-Ab-Opaque-Qtz-Hnbd Ab-Qtz-Hnbd Sch is t pre D2 post 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. British Coluwbia f r e s h - medium greenish grey Grain Size f i n e t o medium w i t h coarse carbonate l e n s o i d s / v e i n s Mineralogy Quartz 40* Accessory Plagioclase(AnO-10) 10* Fe-oxide Hornblende 20* s t a i n i n g Carbonate 15* C h l o r i t e 10* Opaque 05* Textures Massive t o weakly layered ; composi t ional 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 sch is tose toward top Hornblende - occurs as random splays i n p lanar 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 po rphy rob las 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 re fe r red 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 [ B 1 f ] 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 rey ish green Grain Size f i n e t o medium w i t h coarse hornblende Mineralogy Quartz 35* C h l o r i t e 30* C l i n o z o i s i t e / E p i d o t e . . . 2 5 * Plagioclase(?An35?) 05* A c t i n o l i t e 05* Textures Medium layered 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 ; upsect ion grades i n t o lenso id /sphero ids i n a c h l o r i t i c m a t r i x ; composi t ional l a y e r i n g 11 t o f o l i a t i o n Assemblages Ands-Act-Clz-Chl -Qtz Name Clz -Ch l -Qtz Sch is t Page 128 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia b] a ,b} Colour Grain Size Mineralogy Textures Assemblages Name Colour weathered - ye l low green t o whi te f r e s h - pale green f i n e t o medium C h l o r i t e 35% C l i n o z o i s i t e 30% Quartz 20% P lag ioc lase (An37) 10% C a l c i t e 05% Genera l ly massive w i t h Qtz-Cc-Clz ve in ing | | t o f o l i a t i o n C h l o r i t e - dimensional p re fe r red 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 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 Cc-Ands-Qtz-Clz-Chl Ands-Qtz-Clz-Chl Sch is t weathered - brownish-grey t o greenish grey f r e s h - ye l low green t o o l i v e black Grain Size medium t o coarse Mineralogy Hornb lende /Ac t ino l i te . .60% P lag ioc lase (An36) 25% Epidote 15% Textures Medium t o coarse ly layered ; composi t ional 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 o f composi t ional l a y e r i n g 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 o f smal ler g ra ins o u t l i n e f o l i a t i o n ; l a r g e r g ra ins l i e a t h igher angles t o f o l i a t i o n and are o f t e n t runca ted by smal le r ; pargas i te occurs i n massive u n i t s Assemblages Name Ep-Ands-Hnbd Ep-Ands-Hnbd Sch is t Page 129 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia [B2c] {V1} [B5c] {J108} [B5d] {J107} Colour weathered - greenish grey " f r e s h - g rey ish green Grain Size coarse w i t h very coarse amphiboles Mineralogy C l i n o z o i s i t e 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 layered ; composi t ional l a y e r i n g o f c l z and amph-plag u n i t s 11 t o f o l i a t i o n Amphibole - weak dimensional p re fe r red 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 Assemblages Ands-Act-Clz Name Ands-Act-Clz Sch is t Colour weathered - r u s t y brown f r e s h - dark green t o black Grain Size f i n e t o medium Mineralogy H o r n b l e n d e / A c t i n o l i t e . . 50* Epidote 15* F e l s i c 35* Textures Medium t o coarse layered ; composi t ional 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 f o l i a t i o n Amphiboles - dimensional p re fe r red 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 Assemblages Ep-Fels ic-Hnbd Name Ep-Fe ls ic Hnbd Sch is t Colour weathered - r u s t brown t o whi te green f r e s h - grey green t o dark green Grain 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 A c t i n o l i t e 70* Accessory C l i n o z o i s i t e 20* Fine opaque Page 130 structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia F e l s i c s . 10% Textures I5e] 1101, 04} Assemblages Name Colour Grain Size Mineralogy Textures Medium t o coarse ly layered ; composi t ional l a y e r i n g o f opaque ' s t r e a k e d ' and c lea 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 - d imensional p r e f e r r e d o r i e n t a t i o n o f smal ler g ra ins o u t l i n e S2 f o l i a t i o n ; l a r g e r g ra ins o r i e n t e d a t var ious angles t o and t runca ted by f o l i a t i o n F e l s i c - C l z - A c t F e l s i c - C l z - A c t Sch is t weathered - grey green t o r u s t brown f r e s h - grey green f i n e t o medium w i t h coarse t o very coarse hornblende Hornblende 20-50% Quartz 56-20% A l b i t e 05-05% Epidote 03-05% B i o t i t e 10-00% C h l o r i t e 05-17% C a l c i t e 00-03% I l m e n i t e 01-00% F i n e l y laye red ; composi t ional 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 lso 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 lenso id /sphero ids ; poss ib le S2 f o l i a t i o n involvement i n medium t o t i g h t f o l d i n g Hornblende - l o c a l l y present w i t h smal ler amounts o f pa rgas i te ; shows a semi-random arrangement most ly w i t h i n p lanar zones C h l o r i t e / B i o t i t e - dimensional p re fe r red 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 - undulatory e x t i n c t i o n and deformat ion 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 I lm-Ep-Parg-Ab-Chl-Bio-Hnbd-Qtz Name Ep-Chl-Bio-Ab-Qtz-Hnbd Sch is 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 Grain Size f i n e t o medium Mineralogy Quartz 85-90* Accessory B i o t i t e 10-05* Garnet Muscovite 05-03* Magneti te C h l o r i t e 00-02* Textures Fine t o medium l a y e r i n g ; composi t ional l a y e r i n g o f g r a p h i t i c and quartzose u n i t s most ly | | t o S2 f o l i a t i o n ; t i g h t f o l d s o f compos i t iona 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 invo lved i n coax ia 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 de f ines S2 f o l i a t i o n ; some gra ins a t h igh angle t o f o l i a t i o n are k inked; associated w i t h opaques; some growth along S3 cleavage planes Quartz - e longate | | t o S2 f o l i a t i o n ; g r a i n boundries are se r ra ted and hazy; undulatory e x t i n c t i o n and deformat ion bands are common; coarser g ra ins could belong t o ve in ing I | S2 Assemblages Bio-Qtz Musc-Bio-Qtz Name Musc-Bio Q u a r t z i t e [C1b] {J104} Colour weathered - l i g h t brown and dark grey f r e s h - grey t o medium blue grey Grain Size f i n e t o medium Mineralogy Quartz 85-90% Accessory B i o t i t e 08-05* Garnet Muscovite 00-03* Magneti te C h l o r i t e 00-02* Epidote Hornblende 05-00* Graphi te Textures F ine t o medium l a y e r i n g ; composi t ional l a y e r i n g o f g r a p h i t i c and quartzose u n i t s most ly | | 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 structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia composi t iona 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 invo lved i n coax ia l up r i gh t medium f o l d s whose a x i a l plane i s represented by a spaced cleavage Micas - dimensional p re fe r red o r i e n t a t i o n de f ines S2 f o l i a t i o n ; some gra ins a t h igh angle t o f o l i a t i o n are k inked Quartz - e longate j | t o S2 f o l i a t i o n ; undula tory e x t i n c t i o n and deformat ion bands are common; g r a i n boundries are ser ra ted 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 Bio Q u a r t z i t e w i t h l o c a l Ep-Hnbd-Bio Quar 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 [D1a] {J45} Colour Grain Size Mineralogy Textures Assemblages Name CROOKED LAKE PHYLLITE weathered - grey brown t o tan and rus ty brown t o pale green f r e s h - grey t o grey black and rus ty orange 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 a n k e r i t e Quartz 15-30% Muscovite 05-35% Anker i t e 50-00% C h l o r i t e 30-05% Graphi te 00-30% Medium layered ; composi t ional 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 renu la ted by two l a t e r cleavages Chl-Graph-Qtz-Musc Musc-Qtz-Chl-Ank Graph-Qtz-Musc P h y l l i t e i n t e r l a y e r e d wi thz Qtz-Chl-Ank Sch is t pre D2 post Qtz Muse Chl Ank Unit D1a, D1b, D1c [02a] {J52} Colour weathered - r u s t y coa l grey t o l i g h t grey brown f r e s h - grey whi te t o medium grey and red brown Grain Size very f i n e t o f i n e Mineralogy Quartz 80-25% Page 135 and structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British colunbia Muscovite 08-40% C h l o r i t e 10-05% Graphi te 02-25% C a l c i t e 00-05% Fine t o medium layered ; composi t ional l a y e r i n g o f p h y l l i t e and sandstone a t h igh 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 composi t ional l a y e r i n g ; f o l i a t i o n i s open fo lded about a steep ax is toward the n o r t h Cc-Chl-Graph-Qtz-Musc Musc-Chl-Qtz 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 pre D2 post Qtz | - — | Muse j • Chl j j Mm j Tour Unit D2 ( Textures Assemblages Name [D3a] <J41> Colour weathered - dark brown t o ye l low r u s t brown f r e s h - l i g h t grey t o ye l low grey Grain Size f i n e t o medium Mineralogy K-Feldspar 80% Quartz 10% P y r i t e 10% Textures Massive; a s o l i t a r y one t o two meter u n i t se t i n p h y l l i t e ma t r i x K-Feldspar - conta ins abundant quar tz i n c l u s i o n s t h a t resembles myrmekite; poss ib le 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 quar tz cement Page 136 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia [D2b] {J40} [ D l b ] {J57} Assemblages Py-Qtz-Kspar Name Myrmeki t ic-Kspar Meta-arkose Colour weathered - r u s t y coa l grey and tan f r e s h - grey black and whi te grey Grain Size very f i n e t o medium Mineralogy Quartz 70-30* Muscovite 20-30* C h l o r i t e 10-05* Graphi te 00-35* Textures Medium layered ; * 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 ; composi t ional l a y e r i n g a t h igh 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 lanar t o open/medium f o l d s o f composi t iona l l a y e r i n g ; 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 tan f r e s h - grey t o grey-b lack , whi te , and rus ty orange Grain Size very f i n e w i t h coarse a n k e r i t e Mineralogy Anker i t e 85-10* C h l o r i t e 00-45* Quartz 02-20* Muscovite 10-05* Textures F i n e l y laye red ; vague composi t ional l a y e r i n g o f a n k e r i t e and musc-chl -qtz u n i t s a t h igh angle t o S2 f o l i a t i o n Anker i t e - al ignment o f g ra ins 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 composi t iona l 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 Assemblages Name [D2c] { J 9 } Colour Grain Size Mineralogy Textures Qtz-Musc-Ank Musc-Ank-Qtz-Chl Otz-Musc-Ank Sch is t and Musc-Ank-Qtz-Chl Sch is 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 q u a r t z i t e weathered - r u s t y coa l grey t o l i g h t grey f r e s h - grey whi te and medium grey very f i n e t o f i n e w i t h coarse i l m e n i t e Quartz 30-40% Muscovite 20-50% C h l o r i t e 01-05% Fine opaque 48-04% I l m e n i t e 01-01% Accessory Tourmaline F i n e l y layered and medium layered ; composi t iona 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 the smal ler scale and quar tz i te /sands tones and p h y l l i t e / s i l t s t o n e s on the l a r g e r scale predominately 11 t o S2 f o l i a t i o n where f o l d i n g o f composi t ional l a y e r i n g i s t i g h t ; l ess common are occurrences o f open t o medium f o l d i n g o f composi t ional l a y e r i n g where the S2 f o l i a t i o n / cleavage i s a x i a l p lanar ; 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 rge angle t o S2 f o l i a t i o n and i s associated 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 composi t ional 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 Muscovite - dimensional p re fe r red 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 ; polygonal arcs 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 augen- l ike masses; basal cleavage i s genera l l y o r i en ted a t h igh angle t o S2 f o l i a t i o n I l m e n i t e - h igh angle g ra ins are bent and show pressure shadows | | t o S2 f o l i a t i o n Assemblages I lm-Graph-Chl-Qtz-Musc Page 138 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia I lm-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 Quar tz i te Colour weathered - l i g h t green t o t a n green f r e s h - green grey Grain Size f i n e Mineralogy Quartz 90% Muscovite 08% C h l o r i t e 02% Textures F i n e l y laye red ; composi t ional l a y e r i n g o f 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 igh angle t o f o l i a t i o n ; f o l i a t i o n associated w i t h recumbant open/medium f o l d s of composi t iona l l a y e r i n g ; f o l i a t i o n i s invo lved 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 compos i t iona l l a y e r i n g i s t ransposed; up r i gh t k ink forms of f o l i a t i o n a lso occur w i t h t rends a t h igh angle t o the 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 s i l t s t o n e p re D2 post Q t z M u s e C h l (Ab) l l m ( K - s p a r ) (Py) U n i t D3 [D2dJ {J69} Colour weathered - r u s t y coa l grey t o l i g h t grey f r e s h - grey whi te and medium grey Grain 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 Textures Assemblages Name [D ie ] {J77} Colour Grain Size Mineralogy Textures Assemblages Name [D4a] {J67} Colour Quartz 30-40% Muscovite 20-50% C h l o r i t e 02-06% Fine opaque 48-04% Fine t o medium layered ; composi t ional 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 pervasive h o r i z o n t a l f o l i a t i o n i s c renu la ted by S2 f o l i a t i o n ; abundant quar tz ve in ing occurs Chl-Musc-Qtz-Graph Graph-Chl-Qtz-Musc 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 weathered - t a n t o grey and r u s t y brown t o pa le 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 anker i te Quartz 15-30% Muscovite 05-35% Anker i t e 50-00% C h l o r i t e 30-05% Graphi te 00-30% Medium layered ; composi t ional 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 igh angle t o f o l i a t i o n ; S2 f o l i a t i o n c renu la tes 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 Musc-Qtz-Chl-Ank Chl-Graph-Qtz-Musc 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 Sch is t and minor Q u a r t z i t e weathered - l i g h t grey t o coa 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 lag ioc lase and c h l o r i t o i d Mineralogy Quartz 55-30* Accessory Muscovite 10-40* Tourmaline C h l o r i t e 10-05* P lag ioc lase 15-10* C h l o r i t o i d 05-05* Graphi te 00-05* I l m e n i t e 05-05* Textures F i n e l y layered ; composi t ional l a y e r i n g of p h y l l i t e and po rphy rob las 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 de f lec ted by porphyrob las ts Micas - d imensional 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 Andesine - most abundant porphyrob las 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 , con ta in ing i n c l u s i o n s of c h l o r i t e , quar tz , and tourmal ine C h l o r i t o i d - p o i k i l o b l a s t i c , con ta in ing most ly quar tz 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 rom andesine by c h l o r i t e - F e oxide r im ; basal planes are c o n s i s t a n t l y o r i en ted 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 - most ly a l igned 11 t o S2 f o l i a t i o n ; where a t h igh angle show w e l l developed pressure shadows o f quar tz Assemblages Ctd-I lm-Chl-Musc-Ands-Qtz Chl-Ctd-I lm-Graph-Ands-Qtz-Musc Name Ilm-Ctd-Graph-Chl-Musc-Ands-Qtz Sch is t Page 141 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Qtz Muse Chl Ctd Olig Gn (Staur) D2 D3 Unit D4a, D4b, D4c [D2e] {J66} Colour Grain Size Mineralogy [D3c] {J166} Textures Assemblages Name Colour Grain Size Mineralogy weathered - r u s t y coa l grey t o l i g h t grey f r e s h - grey whi te and medium grey very f i n e t o f i n e w i t h coarse muscovite Quartz 30-35% Muscovite 20-45% C h l o r i t e 02-06% Graphi te 48-04% C a l c i t e 00-10% F i n e l y laye red ; composi t ional l a y e r i n g o f l imy 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 quar tz and c a l c i t e ve in ing occurs Chl-Musc-Qtz-Graph Graph-Chl-Cc-Qtz-Musc 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 weathered - brown grey t o t a n f r e s h - l i g h t grey t o green grey very f i n e t o f i n e Quartz 10-25-45% C a l c i t e 05-35-00% Muscovite 00-10-15% C h l o r i t e 20-10-00% Plagioclase(AnO) 50-15-00% Epidote 10-00-15% Fine opaque 05-02-00% Page 142 Structural Geology of Part of the Crooked Lake Area, quesnel Highlands. British Coluwbia Graphi te 00-03-25% Textures Complexly laye red ; composi t ional l a y e r i n g o f l imy 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 k inked 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 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 [D2 f ] {J169> [D2g] {J115} Colour weathered - r u s t y grey t o l i g h t grey - f r e s h - grey whi te and medium grey Grain Size very f i n e t o f i n e Mineralogy Quartz 30-35% Muscovite 20-45% C h l o r i t e 02-06% Graphi te 48-04% C a l c i t e 00-10% Textures F i n e l y laye red ; composi t ional l a y e r i n g | | t o S2 f o l i a t i o n ; abundant quar tz ve in ing 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 - rus ty grey t o t a n f r e s h - grey whi te and medium grey Grain Size very f i n e t o f i n e Mineralogy Quartz 30-35% Muscovite 20-45% C h l o r i t e 02-06% Graphi te 48-04% C a l c i t e 00-10% Textures F i n e l y layered 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 ; composi t ional l a y e r i n g o f | | t o S2 Page 143 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British colunbia [D2hJ {J84> Assemblages Name Colour Grain Size Mineralogy Textures Assemblages Name f o l i a t i o n w i t h som t i g h t f o l d s developing; abundant quar tz ve in ing Chl-Musc-Qtz-Graph Graph-Chl-Qtz-Musc 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 weathered - r u s t y coa l grey t o dark grey f r e s h - grey whi te and medium grey very f i n e t o f i n e w i t h coarse muscovite Quartz 30-35% Muscovite 20-45% B i o t i t e 02-06% Graphi te 48-04% C a l c i t e 00-10% F i n e l y layered w i t h abundant quar tz ve in ing and boudinage; composi t ional 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 porphyrob lasts Bio-Musc-Qtz-Graph Graph-Bio-Qtz-Musc Musc-Qtz-Graph P h y l l i t e [D4b] {J85> Colour Grain Size Mineralogy Textures weathered - l i g h t grey t o coa l grey f r e s h - medium grey 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 lag ioc lase and c h l o r i t o i d Accessory Tourmaline Quartz 55-30% Muscovite 10-40% C h l o r i t e 10-05% P lag ioc lase 15-10% C h l o r i t o i d 05-05% Graphi te 00-05% I l m e n i t e 05-05% F i n e l y l aye red ; composi t ional l a y e r i n g o f p h y l l i t e and porphy rob las 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 de f l ec ted by Page 144 structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Assemblages Name porphyrob las ts ; l o c a l l y c renu la t i ons are w e l l developed away f rom porphyroblasts Micas - dimensional p re fe r red 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 ; Andesine - most abundant porphyrob las 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 , con ta in ing i n c l u s i o n s o f c h l o r i t e , quar tz , and tourmal ine ; shows i n t e r n a l l y r o t a t e d S i | | S e near g r a i n boundries C h l o r i t o i d - p o i k i l o b l a s t i c , con ta in ing most ly quar tz 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 con tac t w i t h andesine; basal planes are c o n s i s t a n t l y o r i en ted 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 - most ly a l igned | | t o S2 f o l i a t i o n ; where a t h igh angle show w e l l developed pressure shadows of quar tz Ctd-I lm-Chl-Musc-Ands-Qtz Chl-Ctd-I lm-Graph-Ands-Qtz-Husc I lm-Ctd-Graph-Chl-Musc-Ands-Qtz P h y l l i t e [ D 2 i ] {J154} Colour weathered - brown grey t o green grey f r e s h - l i g h t t o medium blue grey Grain 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 F e l s i c 25-62% B i o t i t e 05-03% Epidote 05-15% A c t i n o l i t e 60-20% R e l i c t Hornblende...03-00% Fine opaque 02-00% Textures F i n e l y layered ; composi t ional l a y e r i n g o f 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 lded A c t i n o l i t e - dimensional p re fe r red 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 genera l l y have dark cores ( o r i g i n a l ) and l i g h t r ims ( a c t i n o l i t e ) ; b i o t i t e i s associated w i t h these c r y s t a l s Assemblages Hnbd-Ep-Bio-Fels ic-Act B io -Ep -Ac t -Fe l s i c Name Ep-B io -Fe ls i c -Ac t P h y l l i t e i n t e r l a y e r e d w i t h Ep-Ac t -Fe ls i c M e t a - s i l t s t o n e [D3d] {J152} Colour weathered - brown grey and pale green f r e s h - medium grey and g rey ish 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 a n k e r i t e Mineralogy Quartz 15-45* Plagioclase(AnO) 10-35* C a l c i t e 30-05* Epidote 20-08* P y r i t e 10-00* Anker i t e 00-05* Muscovite 05-02* C h l o r i t e 10-00* Textures Massive t o s l i g h t l y layered; composi t ional l a y e r i n g o f c a l c i t e and r u s t y opaque bear ing 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 k inked 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 tw inn ing and l a t e k i n k i n g ; mosts tw ins are o r i en ted c lose t o 30 degrees f rom S2 f o l i a t i o n ; k i n k i n g predominates where tw ins are o r i en ted | | t o S2 f o l i a t i o n Assemblages Musc-Py-Ab-Qtz-Cc Musc-Cc-Ank-Ep-Ab-Qtz [D2J] {J118} 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 coa l grey t o l i g h t grey f r e s h - grey whi te and medium grey Grain 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 Textures Assemblages Name Colour Grain Size Mineralogy Textures Quartz 30-35% Muscovite 20-55% C h l o r i t e 02-06% Graphi te 48-04% F i n e l y laye red ; composi t ional l a y e r i n g o f l imy 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 k inked Chl-Musc-Qtz-Graph Graph-Chl-Qtz-Musc 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 weathered - l i g h t grey t o coa l grey f r e s h - medium grey 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 C h l o r i t e 20-10% Accessory Muscovite 20-45% Tourmaline Quartz 45-30% Graphi te C h l o r i t o i d 03-03% I l m e n i t e 01-01% Garnet 01-01% F i n e l y l aye red ; composi t ional l a y e r i n g o f micaceous and quartzose u n i t s | | S2 f o l i a t i o n ; a second composi t ional l a y e r i n g i s seen developing a t h igh 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 renula tes S2 f o l i a t i o n Micas - d imensional p re fe r red 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 lesser 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 f o l i a t i o n Garnet - se r ra ted 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 e c lose t o g r a i n boundries I l m e n i t e - most ly | | t o f o l i a t i o n ; where a t h igh angle shows w e l l developed quar tz pressure shadows Page 147 Structural Geology of Part of the Crooked Lake Urea. Quesnel Highlands. British Colunbia Assemblages Gn-I lm-Ctd-Muso-Chl-Qtz Name Gn-I lm-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 Grain Size Mineralogy Textures Assemblages Name [E2a] {J65, J 1 , J2} Colour weathered - r u s t y yel low green t o dark green f r e s h - p i s t a c h i o green and dark green 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, hnbd-ep -p lag - (q tz ) , and e p - p l a g - ( q t z ) Plagioclase(AnO) 50-45% Epidote 07-03% C a l c i t e 03-05% Muscovite 25-35% C h l o r i t e 05-00% Quartz 05-10% Hornblende 05-02% Massive t o very coarse ly layered ; conta ins c las ts / f ragmen ts w i t h or w i thout pressure shadows, s p h e r u l i t e s , and abundant contor ted cross c u t t i n g veins 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 igh angle v a r i e t i e s are inc luded w i t h f i n e opaque and grow on or around hornblende Epidote - forms ve ins t h a t cu t across f o l i a t i o n a t low t o h igh angles; broken, d iscont iuous , and h i g h l y con to r ted Hornblende aggregates form pressure shadows on ep-plag Cc-Qtz-Chl-Hnbd-Ep-Musc-Ab Hnbd-Ep-Cc-Qtz-Musc-Ab 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) 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 whi te 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 porphyroc las ts and e l l i p s o i d a l ob jec ts Mineralogy Quartz 15-15% Accessory Plagioclase(AnO) 23-50% Sphene A c t i n o l i t e 45-02% C a l c i t e 05-30% Epidote 05-00% C h l o r i t e 07-03% Textures F i n e l y layered ; composi t ional l a y e r i n g of cc -ab-q tz and a c t - a b - q t z u n i t s i s d iscont inuous 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 poss ib ly f o l d e d as w e l l ; f o l i a t i o n i s invo lved i n open f o l d s associated w i t h a spaced clevage Quartz - shows undulatory e x t i n c t i o n , deformat ion banding, and r ibbon g ra ins ; genera l l y c-axes o f g ra ins l i e c lose t o plane o f f o l i a t i o n A c t i n o l i t e - dimensional p re fe r red 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 poss ib ly 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 My lon i te w i t h Cc-Ab-Qtz and Chl-Ep ve in ing Qtz Ab Cc Muse Act Chl Ep Mylonite D2 D3 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 Grain Size Mineralogy Textures Assemblages Name [E2b] {J168} Colour Grain Size Mineralogy Textures Assemblages Name [E1b] {J144} Colour Grain Size Mineralogy f r e s h - b lue grey t o grey green very f i n e t o f i n e Quartz 20-57% Accessories Plagioclase(AnO) 69-40% A p a t i t e Opaques 01-01% A c t i n o l i t e C h l o r i t e 10-02% C a l c i t e Medium layered ; composi t ional 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 ook ing u n i t s | | t o S2 f o l i a t i o n Ch i /Ac t - 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 C a l c i t e - seems t o form a cement f o r f e l s i c g ra ins Chl-Qtz-Ab Chl-Ab-Qtz 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 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 Plagioclase(AnO) 60-45% Quartz 20-35% C h l o r i t e 18-15% Opaques 02-05% 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 b recc ia u n i t s . Layer ing | | S2 f o l i a t i o n . Chl-Qtz-Ab Ch l -q tz -ab meta-sandstone weathered - r u s t y pale green f r e s h - grey t o grey green and dark green extremely coarse c l a s t s w i t h minor f i n e gra ined m a t r i x Plagioclase(AnO) 45-40% Quartz 02-10% Hornblende 05-20% Page 151 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia C h l o r i t e 35-05% Epidote 13-25% Textures Massive; c l a s t s are rounded t o sub- rounded w i t h l ess than 20% mat r i x ; f o l i a t i o n cannot be c l e a r l y d iscerned 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 invo lved i n u p r i g h t medium f o l d s 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 - pale 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) 68-45% Quartz 20-40% C h l o r i t e 10-10% Opaques 02-05% Textures Coarsely layered 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 pophyrob las t ic meta-andesi te; 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 gra ined u n i t s ; contac ts 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 con tac ts are common Page 152 Structural 6eology of Part of the Crooked Lake Area, Quesnel Highlands, Br i t ish colunbia 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 porphyrob las t i c meta-andesi te [E4a] {J155} Colour weathered - pale green t o rus ty green grey f r e s h - green grey Grain Size f i n e t o medium Mineralogy Plagioclase(AnO) 70-40% Quartz 15-35% C h l o r i t e 10-20% Opaques 05-05% Textures Massive t o medium layered ; composi t ional l a y e r i n g o f sandstone and p h y l l i t e a t h igh angle t o S2 f o l i a t i o n and invo lved 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 gen 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 p h y l l i t e s Page 153 structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British coluwbia APPENDIX B This appendix conta ins a comp i la t ion o f the s t r u c t u r a l data c o l l e c t e d a t the Crooked Lake area. Geographic coord inates and a l t i t u d e s are g iven f o r the S t a t i o n Locat ions i n d i c a t e d (a l so , see Geologic Hap, P l a t e I ) . The data, i t s e l f , i s g ross ly d i v ided i n t o p lanar and l i n e a r f a b r i c s ; the p lanar data i s subdiv ided i n t o Frac tures , Bedding, F o l i a t i o n s , and Cleavages, whereas, the l i n e a r data i s subdiv ided i n t o T igh t , Medium, and Open Fold Hinges and General L inea t ions . 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 low f u t h e r subdiv ided of these 8 basic ca tegor ies : FCT - f r a c t u r e FH - f o l d hinge QVN - quar tz ve in ing FHS - hinge o f f o l d w i t h ' s ' vergence KBB - k ink 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 se t FHM - hinge of symmetric f o l d BOD - bedding or composi t iona l l a y e r i n g LN - l i n e a t i o n ENS - enveloping sur face 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 of open f o l d s LNM - minera 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 of f o l d e d ve in 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 ax is of k ink Page 154 Structural Geology of Part of the crooked Lake Area. Quesnel Highlands, British Colunbia Station Eleu. Long. Lat. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [MEOIUK] [OPEN] [LIN] ID Feet 120o-x'U52o-y'K IDStrDipDD IDStrOipDD IDStrOipDO IOStrOipOD IOTrePlu IDTrePlu IDTrePlu IDTrePlu oaoooooooooooaoaooooooooooaooaoooooaoaoeaooooooooaoooooooooooooooooooooooooooooaoeooooaoooooooooooooooDoooaooaaoooooiieoaDoo J1 3200 47.4286 14.3913 J2 3200 47.2143 14.4130 FCT 70 90 J3 3300 46.1429 14.4848 J4 3S00 43.3571 14.5435 J5,5a 3550 43.2321 14.4891 43.6250 14.3804 800172 BSE 8DD158 601) BD0130 BBU F0L171 85E F0L175 80E F0L172 85E FOL 3 75E FOL 90 21N F0L155 66U FOL158 60U J6 3550 43.1429 14.5000 J8 3300 43.75DD 15.4348 J9 3400 43.5536 15.2826 J10 3450 43.3929 15.1196 J11 3500 43.1786 14.934B BDD140 56SU BDD180 56U ENS 74 62N ENS 93 67N APO 42 35NU CLV 8 E5U a V 52 S9NU CLV 62 29NU FH1I352 IB FH355 15 FOL140 SOU F0L146 76E FOL120 90 F0L113 02U FOL110 90 FOL121 90 FOL110 78NE FOL132 88NE FOL130 BBU F0L140 90 F0L142 54U FOL 158 70U FOL130 90 FOL125 85E F0L12B 60NE FOL126 57E FOL140 56SU FOL1ZO 70SU FOL169 65U F0L17B 65U F0L180 56U F0L1B5 67U F0L157 59U F0L156 72U FOL 30 73NU FOL 72 69NU FOL 76 73NU FOL 72 80NU FOL 72 78NU FOL 90 88N FOL116 74SU F0L115 74U F0L175 48U 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 APT 25 8PO 32 APO 56 APO 32 AP0175 65NU 40NU 36NU 66NU 60U LN 25 16 LNC329 71 LN324 46 LNS142 20 FHS340 40 FH294 66 FHH32B 55 LN288 15 FH313 25 FN295 30 CLV115 76NE FH292 45 FH286 45 FH305 43 CLV170 55U FN295 59 CLV137 85E LN314 35 a v 72 74NU LNC274 60 APH133 90 FH2B5 60 FH335 70 FH198 15 LNI259 28 APN130 83NE FH274 33 LN284 8 APO 14 3BU FH295 35 LN295 46 APN102 85NE FH310 51 LN278 SB APN130 64SU FHS284 48 LN310 48 8PT1Z0 55SU RPH138 60SU2 APK156 61SU APH142 67SU structural Geology of Part of the Crooked Lake Area, quesnel Highlands. British Colunbia Station Eleu. Long. Lat. [FRACTURE] [BEODIKG] [FOLIATION] [CLEAVAGE] [TIGHT] [NEOIUH] [OPEN] [LIN] 10 Feet 120°-x'U52e-y'N IOStrOipDO IDStrDipOO IOStrOlpOO IOStrOipOD IOTrePlu IDTrePlu IOTrePlu IDTrePlu oaaooooooooooooooooooooooooooooooooooooooooeooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo 312,13 3300 43.1071 15.0543 314 3500 42.9643 14.5326 ENS 28 49NU ENS 12 36SE ENS 90 48S 315 3550 43.9464 14.1413 J16 3558 44.4634 13.8152 0VN100 36N FCT132 BSE FCT 62 7BN 319 3600 45.0357 13.9565 FCT 74 B5S 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 FOL120 87U FOL 135 88E FOL123 75E FOL136 B5U F0L150 86U FOL144 BOE FOL127 86E FOL125 88E F0L145 83U F0L153 6BE Page 156 APD150 76U APH16S 62U 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 FH1B2 50 FH2307 42 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 LN312 52 LN107 35 LNR306 43 LN309 70 LN299 41 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] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [KE0IUH] [OPEN] [LIN] ID Feet 120°-x'tfiZo-y,N IOStrDipDD IOStrOipDO IOStrOipOD IOStrOipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu oooooooooooooooooooooooooooooooooooooooooooooooooooooeooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo J19 (cont.) J21 3500 44.6071 13.8261 J22 3300 43.7857 13.1733 FC1 48 2SRU J23,24 4000 43.8036 13.2391 FCT 48 26NU 43.9464 13.3261 J26 3550 43.4643 14.2335 J27 36D0 43.6071 15.1304 J2B 3700 43.7500 15.0217 329 3800 43.8929 14.9891 J30 3300 44.0714 15.0326 J31 4000 44.2143 15.0378 J32 4200 44.4286 14. J33 3700 43.6071 14.7174 F0L165 90 F0L165 B8U FOL165 B6E FOL153 85E F0L170 75U FOL153 SOU F0L160 63U 800170 63U FOL165 55U RPII153 68E FH2336 26 LNC338 31 FOL360 60U F0L170 70U FOL185 65U F0L165 55U BPH153 68E FHZ336 26 LNC338 31 FOL 0 SOU F0L170 70U FOL1B5 65U BDD132 30 FOL125 66SU 8PM43 63SU FHR3BB 30 BDD13B 74U F0L135 B5E APN138 74U FHH315 53 B0D157 68U FOL156 66U ENS 66 35N FOL192 58U aV 75 53N FNZ322 29 FH298 45 LN2B4 40 F0L175 63U APO 56 45NU LN333 34 F0L176 74U APO 40 70NU FOL147 77U FOL186 21U FOL186 50U F0L172 66U FOL150 70U FOL1B5 76U FQL1B0 B4U F0L173 75U F0L160 63U F0L174 SOU APR 88 76N FH291 52 FOL165 83U APO 75 6BN FH344 60 LN311 10 FOL160 70U FOL15B 70U FOL1B2 55U F0L135 75U F0L162 85U F0L162 B5U FH31B 68 F0L149 B5U FOL150 85U FOL155 75U F0L150 B5U FHS335 55 FOL14D SOU FOL155 56U ENS140 43NE F0L167 76U APO 82 66N FH295 71 FH 10 70 LN323 65 FOL170 65U APO 55 68NU FH302 68 FH344 69 LN322 56 FOL163 82E APT154 62U FH333 31 FH323 62 LNC293 46 FOL170 72U aV 54 68NU FH335 43 LNC310 40 F0L171 B6E APO 6B 60NU FHS340 35 LNS327 15 FOL 15 B2NU UIC311 54 FOL116 B5SU LNS342 3 FOL163 70U LNS349 29 FOL 173 85U LNS355 28 F0L166 65U LNC2S3 59 F0L165 68U LNS324 42 Page 157 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'U52o-y'N IOStrDipDD IOStrOipDD IOStrDipDD IOStrDipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu ooooooooooooooooooaoooooooooooooooooooooooooooooooooooooooeoooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo J33 (cont) J33a 3800 B0D170 E6U BDD148 84U BDD165 66U BD0152 B8U J34 3980 43.7B79 14.8739 J35 4000 44.1071 14.6630 J36.3B 4150 4400 44.4464 14.7065 44.7321 14.7609 340 4400 45.1071 14.6957 J41 4500 45.17B6 14.7826 J42 3300 47.3929 14.4674 ENS 90 36N FOL 5 77U LNC315 59 F0L117 85NE LNC347 39 FOL 5 83U LNV318 50 F0L154 86U LNC358 60 FOL183 74U LNC352 42 FOL168 6BU LNS34B 42 F0L153 69U LNC344 66 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 APO 56 76NU FHH330 29 FHS268 62 LN324 80 F0L1B5 65U APH 32 S4NU FHS325 45 FH290 52 LNI340 21 F0L154 75U APO 52 75NU FH331 64 LNR342 30 F0L149 70NE APO 88 68N LN 30 70 F0L148 84U LN325 75 F0L174 62U LN32B 44 F0L144 70E F0L175 65U APT 72 46R FH 11 44 FH342 67 FHS337 50 LN322 40 FOL 5 BOE APH 48 65NU LN303 54 F0L172 72U LN337 48 F0L162 70U LN176 50 F0L162 60U LN 14 87 LN300 70 F0L160 79U FHS334 25 F0L164 B5U rOLISO 80E F0L140 BOE APN173 72U FHZ335 35 LN334 66 F0L154 7BU AP0135 65NE FH316 46 LN336 30 F0L160 85U FHZ320 45 FOL160 BSE F0L159 BOU F0L166 75U F0L167 85U FHN342 36 FHH335 53 FHH326 50 FHH330 6B FOL1EB 79U APO 9B 64N FH2S5 72 LN334 40 O.V153 98 FOL177 82E APO 50 43N LN341 25 FOL130 68NE Page 158 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 o-x ,U52°-y ,N IOStrOipOD IDStrOipDD IDStrDlpDD IOStrOipOD IOTrePlu IDTrePlu IDTrePlu IDTrePlu ooooooooooooooooooooeoeoooooooeoooooooooooooooDOoooooooooooooooooooooooooooooeooooeoooooooooooooooooooooooooooooooooooooooo 342 (cont) 343 3S00 47.4107 14.6413 344 3000 46.6329 14.8043 345 4000 46.5000 14.8587 346 3180 44.0357 16.0000 347 3400 348 3700 46.2679 15.5652 349 3900 46.1964 15.4B91 350 4080 46.1429 15.3639 351 4200 46.0714 15.2609 352,52a 4600 45.9643 15.1304 4500 45.9206 15.0652 F0L15B BOE F0L170 90 FOL 10 B5U FOL 5 66U FOL170 63E APO120 53NE BD0163 70E FOL 140 85E CLV155 55E 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 LN 2 44 LNI359 40 LN1B8 25 LN21S 35 FH114 50 LNS150 3 LNS317 33 LNS315 45 FH175 23 LN 33 15 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 5 353 3600 45.2679 15.5978 F0L145 83E 354 3900 44.7500 15.5435 ENS185 65NE F0L156 BBU FHS329 67 LN334 355 4000 44.7143 15.2283 F0L148 75E F0L143 SO FHH 32 33 356 4100 44.0750 15.1196 ENS 14 64U F0L165 74U NPD118 86NE FH338 55 FH31D 62 357 4000 45.0179 15.2391 BOD 0 66U F0L154 90 F0L162 75U FOL168 B2U FH3ZB 42 FH344 48 359 3500 47.9021 14.8696 F0L141 39E F0L178 55E FOL159 B3E 360 3400 40.1607 14.3130 FOL165 56E LN340 361 3360 40.0000 14.5887 FOL180 E8E LN 9 6 LN170 20 352 3500 48.0000 14.7500 363 3650 47.0929 14.7500 364 3600 47.5000 14.7935 FCT 75 85S 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 APO 5 15U BPH 30 77NU RPn 53 65RU APR 40 5BNU FH2 30 40 FH FHS 12 36 1 10 LN340 10 LK345 52 Page 159 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 120o-K'U52°-y,K IOStrDipOO IDStrDipOD IDStrOipDD IOStrDipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000009000000000000 J64 (cont) 365 3600 47.6250 14.5543 J56 3550 41.8571 16.3152 F a 15 90 BDD112 32NE J67 41.0179 16.2391 J68 4350 40.8758 16.3043 800115 70NE J59 4950 J7D 5150 J72 3150 40.6607 16.4239 40.5357 16.4348 FCT158 B4U FCT 72 56S 37.6429 14.4783 J73 3350 J74 3600 J75 3ED0 J76 3850 J77 5000 38.8393 14.8152 38.8036 14.8587 3B.6250 14.8370 FCT162 75U 39.7500 15.3370 QVN105 60NE 41.5714 17.0217 KBB170 66E 41.9107 17.1522 FCT 98 3BNE 800116 30NE BDO 82 22N ENS 92 18S BDD150 7BE ENS150 BBU J78 5550 40.5357 16.6630 FCT 3B 80SU BDD100 74NE FCT 60 6DSE BDD16B 55NE F0L175 75E F0L162 70E F0L169 75E F0L164 72U FOL 16 6BE F0L175 73E FOL 5 90 F0L110 3BNE F0L112 32NE F0L115 30NE F0L111 24NE 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 F0L116 30NE FOL104 25NE FOL 98 34NE F0L11D 35NE FOL105 52NE F0L121 45NE F0L103 SOME 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 FOL120 37NE FOLIOS 34NE O.V144 57SU CLV13B 78SU aV 82 26N APH B4 35N 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 LH320 35 FHS295 20 LN311 17 LN317 16 LN290 9 LN296 6 LN8293 9 LN315 22 FH320 32 FHZ295 10 FH305 18 LNR310 20 FH295 10 FH3DB 13 FHZ311 21 LN203 10 LN29S 5 LN301 16 FH290 21 LN294 4 FH290 14 LN292 0 LNR310 5 FH320 41 FHS335 20 LNK 5 34 FH336 23 LN335 22 LN330 22 Page 160 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) FCT 7B 17N BDD160 73U FOL100 31NE APH1E6 57SU LN335 25 QVN 57 3DNU F0L135 SENE LN340 21 F0L140 TONE LN297 14 382 5800 40.0536 16.5543 FOL109 44NE APO110 BOE FH229S 50 FOL12S 60NE 383 6100 39.1429 15.7826 0VN123 48NE BDD12S 31NE FLC125 31NE a«125 68NE FH315 15 LN306 3 9VN114 20NE LNB337 17 CF1166 03U CF2 50 B5NU 384 5900 39.1964 15.7609 071177 B8E BDD11S 25SU FLC123 20NE O.V111 52NE CF2 70 86U B0D117 60SU FLC120 25NE FCT167 74E FLC147 3SNE J85 5500 39.3393 15.6848 F a 2 83U 8001IB 25NE F0L115 34NE aV124 74NE LN294 2 FLC118 Z5NE LN110 8 FLC12B 20NE LN295 4 FLC134 30NE LN299 12 F0L107 ZONE JBE 5000 39.4464 15.597B QVN114 45NE FLC105 32NE avi70 64E FH2B4 15 LN290 10 Faifi5 73U FLC 95 30NE FOL 98 44NE F0L114 45NE FOLIOS 42NE F0L119 52NE F0L112 35NE F0L10B 40NE 387 5000 39.7580 15.6522 FOLIOS 35SU AP0115 72SU FHS295 10 FOL104 62NE FOL112 48NE FOL 105 58NE FOL BD 36NE 088 5250 39.7500 15.7B26 Fa 2 B5U FLC109 44NE aV155 58E LN114 2 F0L114 42NE LN296 3 FOL 95 35NE F0L124 26NE J8S 6200 39.4464 16.0543 FCT170 6EU 800118 90 FLC 95 25NE aVIZO 3BNE J30 6250 39.0893 15.7935 FCT164 90 800115 25NE F0L116 50NE aV138 3BNE LNK 16 50 F0171 78U OFL 71 55NU O.V13B 62NE LNI307 9 KBB 10 B5NU FOL125 26NE CLV13B 53NE LN305 7 F0L116 3BNE aV132 56NE LNB 0 36 F0L115 25IE LN310 10 F0L110 Z5NE LN30D 0 F0L115 39NE LN120 2 FOLIOS 35NE LNR111 3 FOL120 2SNE J91 5650 39.8893 15.7935 FOL116 30NE CLV116 7BNE LN297 0 FOL105 34NE J92 5250 39.2679 15.5978 Fai65 98 FOL104 36NE APO140 75NE FHS315 30 FOL102 45NE AP0130 52SU FHS295 10 FOLIOS 55NE F0L106 49NE J83 5300 39.0893 15.5000 F0L109 42KE LN310 6 FOL11B 36NE FOL110 46NE J94 5400 39.0000 15.5109 F0L111 20NE APH11B 62NE FH3D0 8 FH306 6 LN3D3 15 F0L17B 20E APH116 90 Page 161 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 1ZD0-x'U5Z0-y'N IDStrDipDD IOStrOipOD IOStrOipOD IOStrOipOD IDTrePlu IOTrePlu IDTrePlu IDTrePlu 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 394 (cont) 335 5700 33B 5650 397 5600 398 5600 399 5600 3100 5600 3101 5450 3102 5350 3103 5300 FOL103 38NE F0L114 50NE F0L13D 5ZNE FOLIOS 23NE F0L118 40NE F0L122 46NE F0L116 85SU 38.6607 15.4565 FOL100 30NE FOL 95 32NE 36.6429 15.347B F0L115 32NE FOL110 43NE FOLIOS 25NE 38.5357 15.2826 F0L122 50NE F0L111 41NE F0L115 4SNE FOL129 45NE F0L11B 32NE F0L120 SOKE 3B.3929 15.3043 FCT 15 B3U FOL110 30NE F0L115 54IE F0L119 42NE F0L124 TONE F0L124 52NE F0L125 4BRE 3B.1B71 15.2283 FCT 12 72U F0L13D 36NE FCT 11 B5SE F0L121 40NE FCT137 57SU F0L112 Z5NE FOL110 4ZNE F0L151 19SU FOL 24 10NU FOL SO 30N FOL120 S6IE F0L116 55NE F0L111 30NE F0L12B 24SU 37.7679 15.1630 FOLIOS 63NE F0L119 60NE FOL130 65NE 37.5000 15.1304 FOL120 60NE F0L121 60NE F0L120 54NE 37.4107 15.1087 F0L134 48NE F0L128 4BNE F0L131 30NE F0L182 43E F0L134 25NE F0L14D 65NE F0L135 55NE F0L136 40NE FOL 95 11N F0L149 30NE FOL 15 SHU F0L136 55NE 37.2580 15.1630 F0L112 62NE F0L11B 56NE AP0165 6BE FH345 30 LN310 12 RPH112 70NE RPH113 7BNE 8PH134 BOSU RP0120 74SU 8P0122 72SU RP0110 B3NE FHSZSO 11 FHS2S6 12 FHS305 5 FHS305 10 FHS301 5 FHS305 8 RP0120 BOSU FH296 7 RPN125 76NE FHS297 2 Page 162 structural eeology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia Station Elev. Long. Let. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEDIUH] [OPEN] [LIN] ID Feet 120°-x,U5Z°-y'N IOStrOipOD IOStrOipOD IOStrOipOD IOStrOipOD IOTrePlu IDTrePlu IDTrePlu IDTrePlu OOOOOOOOOOOOOOOOOOOOOOOOOQOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO J104 5100 37.1250 15.119B FCT177 62U 3105 3106 3107 3108 3103 4900 36.9021 15.1087 5360 38.7500 15.2826 5100 38.8214 15.2391 QVN152 66U 5300 38.8571 15.3261 QVN 95 55NE 5650 38.8750 15.5109 KBB175 71E FCT165 53U 3110 3111 6100 3B.7321 15.6087 FCT180 90 FCT 72 52U 5200 39.2143 15.4457 FCT170 BOU 3112 3113 3114 4920 39.3036 15.3913 FCT 12 84U FCT 10 76U 4700 39.6071 15.5217 4700 39.7500 15.5543 800103 42NE FOL140 36SU F0L135 36NE FOL130 TONE FOL120 76SU FOL152 46SU FOL125 49NE FOL120 50NE FOL123 40NEr F0L127 16NE FOL136 53NE F0L121 57NE F0L114 90 F0L120 40NE F0L118 90 F0L114 35SU FOL125 30RE F0L121 45NE F0L100 55NE FOLIOS 36NE F0L13B 40NE FOL130 34IE FOL1S0 42NE FOL1DS 35NE F0L112 34SU FOL115 45NE F0L111 28RE OFL 64 40NU DFL 65 41NU F0L112 52NE FOL122 32NE FOL 96 35NE F0L115 1BNE 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 FOL 93 35NE APT 53 50NU APT BO 34N APT 10 25U APT 75 20NU APT160 5U APT118 42NE APH120 76SU RPK132 90 APH129 72NE APH136 90 aV126 60NE AP0130 90 APO 53 E5SE CLV113 42NE av i 1 4 52NE AP0114 7DNE FH342 45 FH303 24 FN31B 14 FH322 9 FH334 10 FH321 6 FH30B 10 FH309 11 FH308 FH380 FH311 FH309 FH310 10 FN 70 42 FH290 10 LNK 36 34 LN29B 4 LNB318 12 LN 5 56 LIB290 4 FH124 5 APH142 30ME FH10B 2 LN294 11 Page 163 I Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Coluwbia Station Eley. Long. Lat. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEDIUH] [OPEN] [LIN] 10 Feet 1Z0o-x'lfiZs-y'N IOStrOipDD IOStrDipDD IOStrOipDD IOStrDipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 J114 (cant) F0L115 50NE APH12D 36NE FH1ZB 1 LNZ96 10 F0L115 15NE LN30S 12 F0L115 B5SU FaiOS 25NE F0L112 40NE FOLIOS 58NE F0L115 50SU 3115 64Z0 3B.7500 16.0543 FOLIOS 25NE LNR310 13 J11B S9S0 37.5000 15.9457 ENS 5 64U APH 93 40NE FH 10 35 FH 1Z 35 APO 5 70E J117 6950 37.0357 16.1630 FOL 77 50NU HPH126 4ZNE FHS340 50 Fa 90 41NE FH 5 45 J11B 6450 37.3393 15.6413 KBB170 7BE F0L114 63NE aV114 68NE LN301 15 OFL 47 72NU LN304 10 F0L115 45NE LN332 26 FOLIOS 49NE LNB 21 61 F0L116 60NE F0L114 49NE FOL101 36NE F0L110 46NE J119 600B 36.8036 15.4130 FCT175 70U F0L106 55NE LN295 3 F0L115 3BNE F0L112 52NE F0L115 55NE F0L110 50NE F0L115 45NE FOL105 31NE r J1Z0 5BZ0 36.9107 15.2717 F0L125 S2NE LN300 3 F0L120 56NE F0L126 50NE J121 5900 37.2500 15.3043 FCT176 82U F0L12Z S2NE F0L11B 45NE J1ZZ 6000 37.6071 15.3587 F0L115 46NE aVIZO 75NE LN29B 9 F0L112 50NE J142 6920 36.6071 16.4239 FOL 89 6BN LN270 4 Fa 93 65NE LN 76 20 F0L114 64NE LN 7B 27 Fa 92 46NE LN10B 3 Fai05 74NE LN116 0 J143 70Z0 36.6071 16.5326 BOD 68 4BNU F a 92 60N J144 7000 36.5357 16.6304 Fa 73 32NU LN307 40 JUS 7300 36.6786 16.9565 FCT11B 30NE 8DD150 83U Fai22 5SNE FCT113 45NE J147 7220 36.7500 16.7391 FCT 68 45NU BDD118 45NE F a 93 58NE AP0122 30ME FH290 6 LN 94 5 BOD 95 73NE LN254 13 8B0107 53SU LN290 2B 3149 7100 36.8036 16.5326 Fai03 35HE F a 14 3BE Fa 24 B4NU FOL110 60NE Fa 46 54NU F a 34 5BIU Fa 6 64U 3150 6900 36.8929 16.4130 FaiOS 50NE flPmOS 36IE AP0115 24NE FH345 46 LN26B FH 30 18 LNZ95 Page 164 structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, Bri t ish Colunbia Station Elew. Long. Let. [FRACTURE] [BEDDING] [FOLIATION] [CLEAVAGE] [TIGHT] [HEOIUH] [OPEN] [LIN] ID Feet 120 s-x ,U52°-y ,N IOStrOipOD IOStrOipOD IOStrOipOD IOStrOipOD IDTrePlu IOTrePlu IDTrePlu IDTrePlu ooooooooooaoooooooooooooooooooooooooooooooooooaoaooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooaooooaoo 3151 6730 36.6071 16.3043 3152 6600 36.3750 16.2935 3153 3154 6450 6450 3155 6720 3156 3157 7320 36.2500 16.2935 F a 125 DONE 36.0893 16.3761 FCT 94 60N 36.1429 16.4674 FCT176 90 FCT 99 BON FCT107 58NE 35.9286 16.4565 35.4643 16.6087 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 m 78 55NU AP0115 45NE AP0148 56NE BB0136 25SU BD0129 60SU 800136 20SU 800130 40SU Fai05 42NE FLC115 30NE APO 73 90 aV123 32NE aV140 90 APH112 45NE a v 06 44N a v 92 62NE aV113 64NE APH1Z4 50NE aVIlO 66NE 3158 7000 35.3393 16.5435 3159 6920 35.4821 16.3587 BOO 32 56NU FLC110 69NE Fa 42 30NU F a 96 52N Fa 94 30NE F a 95 43NE F a i 5 6 6DSV Fa 105 59NE Fa 96 60NE 3162 3163 7000 6920 38.1071 16.6413 36.4286 16.597B APD140 74SU FHZ300 42 FH310 24 FH320 6 LN270 0 LN314 30 FH 75 32 LN274 IB FH 90 35 FH105 45 FH302 15 FH315 32 BOD 98 66NE F a 90 35N APT 88 46N FH320 30 FH2B9 23 FH300 24 LN 0 35 800140 86RE F a 76 30NU APT 80 42N FH323 27 FH3D5 21 800 66 32NU FOL124 59SU APT 60 30NU FH324 21 FH300 24 FOL103 54NE APT 92 38NE FH319 34 FH307 33 F a 144 65SU APT100 40NE FH315 38 FH305 25 F a 136 72SU APT107 44NE FH314 IB F01103 44NE APT SB 43NE FH323 3D F a 78 40NU APN130 DONE F a 40 24NU APH129 7BNE Page 165 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 120D-x'U52°-y,N IOStrOipOD IOStrOipOD IOStrOipOD IOStrOipOD IDTrePlu IDTrePlu IOTrePlu IDTrePlu OOOOOOOOOOOOOOOOejOOOOOOOOOOOOOOOOOOOOOOOOaOOOOCOOOOOOODOOOOOOOOOOOOOOOOOOttOOOOOOOOOOOOOOOOOOOODOOOOOOOOOOOOOOOOOOOOOBOOOOOtt 3163 (cont) 3164 7120 37.5000 1S.3B04 J165 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 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 Page 166 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 1Z0s-x'U52o-y'N IBStrOipDD IOStrDipDD IOStrDipOO IOStrOipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu OOOOQOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOQOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO RZ1 3860 43.7143 13.0435 R22 38BD 43.6964 13.0761 FCT 65 64S FGL155 61U FH336 10 FCT ZO 70NU FOL158 76U FH359 15 FCT 58 81S F0L1B1 B3U FH350 18 Fa 64 BOS FOL164 67U Fa 50 B8N F0L156 84U Fa 48 BZS F0L167 75U Fa 56 70S FOL148 68U Fa 64 TBS FOL 154 701) Fa 62 73S F0L153 73U Fa 51 65NU FOL151 B2U F a 71 80S F0L156 BOU Fa 61 71S FOL161 73U F a 60 79N F0L161 63U Fa 37 59S F0L158 Bill Fa 24 90 F0L156 84N Fa 41 90 F0L154 BOU Fa 42 78N F0L156 5BU Fa 65 71S Fa 56 72S F a 76 76S FO 50 73N FCT144 45N Fa 40 65S Fa 27 70S F0153 75E FCT133 65NE F a 55 90 F O 47 75S F O 75 59S Fa 70 90 Fa 64 47S Fa 64 90 BDD155 6DU FOL147 BOU FH318 25 Fa 30 80S FOL163 65U Fa 64 76S FOL158 7SU FCT 73 75S F0L161 75U FCT 61 641 FOL161 61U Fa 89 SOS FOL160 D7U FCT 50 73N FOL 160 85U FCT 6B 75N F0L164 75U Fa 50 56N FOL 154 7BU FCT 56 65N F0L156 79U Fa 76 B5N FOL 158 BOU FCT101 58N FOL161 B5U Fa 94 701 FOL164 62U FCT 76 90 FOL154 SOU FCT 69 BOS F0L153 8DU Fa 81 35S FOL155 90 Fa 35 78N FOL154 SOU FCT101 72N FOL158 75U FCT 76 41S FOL160 65U FCT 52 46S F0L151 75U Fa 69 60N FCT 66 54S Fa 69 6BN FCT 64 70S LN338 IB LN331 B LN305 15 LN350 22 LN331 11 LN139 30 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 OOOOOOOOOOODOOOOOOOOODOOOOOOODODOOOOOOOOOOOOOOOOOOOOOOOODOOOOOOOOOOOOOOOOOOOOOOOOOOeeOOaoOOOOOOOOOOOOaOOODOeiOOOOOOOOOOODOt tO RZ2 (cont) RZ3 6850 R24 3BB0 FCT 35 60S FCT 63 SO FCT120 60S FCT 49 73S FCT120 BBS FCT 58 85N 43.6786 13.1196 FCT142 22E QVN 74 90 FCT 82 SO F a 95 84S FCT10D 6SS FCT 98 54N FCT111 90 F a 80 80S FCT 24 76SE 43.5714 13.0870 FCT 59 B4S FCT102 B4S F a 44 90 FCT1DB 90 FCT 69 90 FCT 39 85N F a 50 75S FCT 50 84S FCT 63 BSS FCT 25 BSE FCT 50 72SE FCT 45 7SE FCT 64 76S B0D17S 70U BDD155 60U FOL155 62U FOLISO 70U FOL155 70U FOL1S8 70U F0L15B 68U FOL168 64U F0L154 SSU FOL159 73U FOL149 5BU F0L153 73U F a 152 7QU F a 152 SSU Ftt140 70U F a 151 70U RZ5 3810 RZ6 3920 LNH334 8 LN328 20 LN332 14 FCT 50 BOS F a i 6 3 70U FHZ322 34 LNC320 35 00.106 90 Ftt164 SOU FHZ318 68 LNC342 33 FCT135 BOU F a 175 72U FH328 38 LN334 28 F a 62 82S F a 163 61U FH33B 37 LN335 24 FCT 65 87S Fa 159 78U FCT 65 79S F a 161 BOU FCT 45 85E F a 164 60U FCT 80 828 Fai65 65U FCT130 32N F a 160 63U FCT 90 80S F a 160 73U FCT 56 SO F a 37 90 FCT 58 70S B0D164 60U F a 157 78U FH315 25 FH3Z7 42 LNH338 14 FCT 49 82S , F a 167 63U FH 8 27 FHZ355 36 LNC345 16 FCT150 36E F a i s s BDU FH316 48 FHZ337 49 LN330 27 F a 56 82S F a 156 BOU FH322 15 FH234S 50 LN341 10 FCT 22 90 Fai61 68U FH340 25 LN337 32 FCT 76 61S Fai62 72U LNC337 29 FCT 50 77S Fa 159 71U F a 67 64S F a 159 73U FCT131 30N F a 161 B1U FCT 41 BZE Fai66 76U FCT 40 90 F0L161 76U F a 78 71S F a 168 75U FCT 64 82S FaiS9 76U FCT 36 90 Fai64 85U FHZ346 30 LN337 24 FCT 69 75S Fai59 64U FH30B 40 LKH341 25 Page 168 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 120o-x,U52°-y'N IOStrOipOD IOStrOipOD IOStrOipOD IOStrOipOD IDTrePlu IDTrePlu IOTrePlu IDTrePlu RZG (cant) RZ7 4000 R2B 4050 R29 3360 RZ10 3S0D R211 3820 43. FCT 61 85S FOL17D 60U FHZ325 45 FCT 28 3D FOL162 76U F0L159 5SU F0L171 S1U 43.3214 13.2826 FCT 54 BOS F0L167 70U FCT 25 90 FOL158 80U F a 91 611 FOL160 SOU FCT105 90 F0L160 75U FCT 3B SO FOL165 7TJU F a 2B 90 F0L1S2 BBU F a 45 73S FOL166 75U F O 57 67S F a 41 90 ENS 6 5 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 FH2326 55 FCT148 75U F a 18 52H FHH3D2 70 F a 30 65N FH284 50 F a 15 83N FH295 57 F a 15 86N FH326 43 FHZ329 46 42.9464 13.22B3 FCT12B BON F0L164 75U FH353 70 FH2312 50 F a 43 66U FOL176 68U F a 60 65S F a 5 5BU FCT13B 90 F0L1G8 70U F a 75 SO F a 3 sou F O 45 90 F a 0 65U FCT15D B5S 43.0000 13.2065 FCT166 85SU F a 160 68U a v 19 8BNU FH312 47 F a 8 90 F a 45 68U FH3S5 50 FCT143 70S Fa 5 85U FH318 49 FCT161 05U F a i T S 85U FH2328 SB FCT142 90 Fai65 85U FHZ337 67 FCT 90 55S FOL 160 85U FCT133 90 F a 0 B5U F a 44 65S F a i 7 5 BOE FCT 28 55SE F a 46 S8SE F a 53 BBS F a 25 BSE FCT 50 B4U Fa 22 40U F a 83 5BS F0L171 B1U FCT 70 66S FOL165 64U F a 77 4SS F a 165 70U FCT 57 62U F a 154 76U \ FCT 54 SOSE Fai56 05U F a 66 DOS F a 168 67U FC7113 67N FOL161 72U FCT125 SON Fai60 75U FCT 58 BOS FOL155 75U FOL162 90 F a 0 76U Fai71 70U F a 170 70U 0000 13.1196 F a 64 60S Fai60 82U FH332 50 FH325 50 LNK320 60 LNK323 46 LNH324 37 LNH326 36 LNH332 37 LN330 33 LNH323 27 LNH335 35 LNM10B 15 Page 169 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'U52s-y'N IDStrDlpOD IDStrDipOO IOStrOipOD IDStrOipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu FCT 56 57S FOL158 79V FH339 25 FH300 26 LRC340 40 FCT 55 48S F0L170 03U FH163 25 LHC346 44 FCT 69 39S F0L157 B3U FH ID 8 LRK352 33 FCT 60 43S FOL164 B6U LHH319 35 FCT 57 42S FOL159 BOU LRK336 20 FCT 56 33S F0L149 BOU LRH313 48 FCT 97 4BS FOL165 02U LRK320 40 FCT102 SOS FOL171 73U LRR316 42 FCT1D2 52S FOL169 B1U LNH336 14 FCT105 70S FOL160 90 LRR333 13 FCT 93 SIR F0L160 78U FCT 66 66S F0L140 98 FCT 69 75S F0L163 85U FCT 60 70S FOL 165 84U FCT 74 75S FOL164 82U FCT116 39R FOL164 BOU FCT 67 80S F0L169 65U FCT 56 76S FOL 159 7SU FCT 63 B2S FOL 153 86U FCT 73 60R 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 Page 170 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 i20o-x'U52D-y'N IOStrDipOO IOStrDipOO IOStrDipDD IOStrDipDD IDTrePlu IDTrePlu IDTrePlu IDTrePlu 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 he re ference hinge th ickness , ( tO) , f o l l owed by sucessive l imb th i cknesses ( ta ) away f rom the hinge toward the f o l d ' s i n f l e c t i o n p o i n t ; ( t a ) i s a perpendicu lar th ickness between tangents t o the upper and lower sur faces o f t he f o l d ; next a perpendicu lar t o the a x i a l sur face i s const ruc ted t o i n t e r s e c t the tangent p o i n t o f e i t h e r sur face o f the f o l d . The i n t e r s e c t i o n angle i s the angle between the tangent l i n e and t h i s ' cons t ruc ted perpendicular* . Th is ang le(a) i s p l o t t e d aga ins t the r a t i o o f l imb t o hinge th icknesses ( t a / t O ) . t - a l p h a p l o t s t a n d a r d fo rms 1.6 t = t (mm) / to (mm) 1.2 -10 20 30 40 50 A lpha = a° C lass 1a a C lass 1b C lass 1c • C lass 2 • C lass 3 60 70 80 90 Page 172 Structural geology of Part of the Crooked Lake Area, Quesnel Highlands, British Coluwbia OIIT-STITIM-EPISOIE ALPHA TABU ILPII TAW U N I Till) ALPHA TAW 11 FOLI FOBIS Snowshoe-J72-01 51 .88 80 .32 81 .25 62 .29 43 .93 78 .50 60 .43 82 .32 82 .25 $mwshoe-J74-D1 82 .29 79 .36 61 .50 63 .84 84 .21 83 .19 75 .36 68 .19 89 .21 88 .57 84 .36 88 .16 87 .18 86 .38 88 .16 80 .29 83 .52 82 .14 84 .28 82 .14 86 .26 66 .23 SnoBshoe-J74b-01 86 .14 64 .12 66 .22 83 .18 88 .17 88 .14 87 .18 «irtler-RZ6-81 85 .09 83 .07 81 .07 83 .27 84 .21 85 .20 68 .20 ...12 FOLI FOIIS Phyllite-J57-D2 (open) 18 1.08 50 .92 5 1.00 22 1.00 41 .92 48 .63 46 J 5 Phjfllit8-J40-D2 (open) 3 1.06 0 1.60 5 1.22 10 .62 7 1.22 20 .94 Page 173 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, British Colunbia BlIT-STiTIOi-EHStHE IIHI TMU ILHI THU «.»•• TtBU ILWi TI5U Phyllits-J40-02 (opso) 10 1.00 29 .82 (continued) 22 .89 36 .71 15 1.00 18 1.00 33 1.00 40 1.00 Phyllite-J89-D2 (open) 13 .90 14 .94 26 .90 32 .81 20 .90 25 .56 20 30 1.00 .90 30 8 .94 .88 SnoHshoe-RZ8-D2 (open) 12 1.00 12 1.00 20 .91 94 1.00 30 1.14 49 .64 73 .75 52 1.29 53 .45 16 1.80 9 1.00 33 .82 38 1.13 29 1.00 47 .82 80 1.25 45 .08 54 .82 52 .86 Phyllite-J41-D2 (nediun) 58 .50 77 .29 61 .67 59 .70 77 .33 59 .50 41 .75 75 .46 44 .50 74 .50 66 .87 48 .44 48 .90 71 .42 49 .50 58 .65 80 .48 41 .83 81 .60 85 .54 40 .83 63 .50 60 .87 23 .89 87 .45 63 .65 50 .85 37 .95 80 .45 78 .55 75 .60 65 .75 55 .70 55 .75 51 .85 34 .95 Phyllite-J5-02 (nedim) 34 .95 69 .87 69 .71 74 .67 Page 174 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Coluwbia BlIT-STITIOI-EPISOIt ILPH TMU t t H i TUB ILWI TIIU ILPM TAIU Phyllite-J5-62 (nediun) 76 .62 74 .86 (continued) 78 .57 76 .53 63 . 66 38 . 93 81 .57 66 .87 81 .48 81 .73 85 .43 62 .93 74 M «ntler-8Z8-D2 (nediun) 21 .92 43 .83 55 .67 62 .58 65 .58 85 .42 19 1.17 42 L08 Antler-R25-02 (nediun) 20 1.25 43 1.13 58 1.08 60 1.06 62 1.00 62 1.08 15 .88 48 .75 51 .83 61 J 5 Snovshoe-R210-02 (nediun) 63 .78 40 .94 89 .61 56 .76 66 . 58 73 . 67 61 .81 67 .67 34 .94 79 .39 77. .39 81 J 3 RnUer-R27-02 (nediun) 44 . 90 31 .93 48 . 65 29 1.80 53 . 76 42 . 83 57 . 84 41 .78 57 . 66 48 . 78 34 1.06 61 .59 35 . 65 54 . 72 80 .52 62 .75 60 .78 54 .64 20 1.60 66 .54 89 .48 81 .81 29 .97 70 .46 74 .33 61 .58 25 .97 79 J 3 Phyllite-J28-02 (tight) 88 .64 Page 175 Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands. British coluwbia 0IU-STiTI0H-EHSOBE ILMI TIM ILMt TtlU ALPWW THU tLMi TIIU Phyllite-J28-02 (tight) 66 .43 (continued) SO .79 31 .93 32 .93 50 .86 60 .84 60 .50 64 .43 64 .50 82 .43 85 .56 60 .71 65 .57 71 .38 77 .29 76 .21 Phyllite-J117-62 (tight) 70 .78 63 .55 71 .47 74 .36 74 .39 76 .36 73 .37 79 .36 74 .37 78 .73 60 .88 75 .38 65 .44 77 .45 75 .44 79 .42 Phyllite-J36-02 (tight) 30 .98 62 .71 66 .49 66 .39 71 .35 73 .33 73 .33 69 .61 73 .43 73 .33 74 .27 74 .27 74 .25 78 .24 78 .22 Page 176 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbia  wn-smiw-ErisoiE n m TIIU n m TIIU U P H T H U u r n TIIU Phyllite-J38-D2 (tight) 76 .18 (continued) 60 80 80 .16 .18 .14 Phyllite-J28D-D2 (tight) 7! 83 .62 .33 78 80 .27 .19 83 .29 80 .23 79 .29 75 .31 79 .33 76 .23 79 .29 78 .27 78 85 .87 .23 85 .29 83 .29 Phyllite-J41b-D2 (tight) 20 .98 74 .56 52 .82 55 .75 62 .34 58 .65 85 .56 51 .31 58 .52 88 .55 54 .33 62 .50 67 .52 05 .33 65 .43 58 .52 00 .59 47 .78 57 .48 65 . .48 77 .55 68 .75 54 .42 84 .40 60 .56 54 .44 82 .35 72 .44 56 .45 79 .30 72 .44 78 60 .44 .44 Bntler Cress Section 33 .88 41 .91 (The Basset-Stark 02 Pair 38 .83 55 .75 Cross Section 1 Plate 3) 41 .92 41 .92 51 .78 59 .72 52 .69 78 .57 53 .66 78 .49 54 .64 78 .45 53 .63 77 .42 54 .63 76 .40 54 .63 78 .30 55 .64 75 .38 63 .82 73 .35 80 .58 74 .34 Page 177 Structural Geology of Part of the Crooked Lake Area. Quesnel Highlands, British Colunbia MIT-STITIOI-EPISOBE IIMI TilU I t ' l l TtlU ALPII TIIU M.HI TIIU Antler Cross Section 71 .48 75 .34 (continued) 74 .34 Phyllit8-J98-D3 28 .95 26 .03 34 .93 28 1.80 32 .79 34 .75 47 .71 55 .80 22 .92 27 .93 64 .60 38 .92 40 .88 61 .90 82 .68 84 .50 56 .80 70 .80 79 .60 42 .90 59 .60 63 .70 Phyllite-J104-03 38 .90 43 .03 44 .08 43 .75 48 .80 40 .03 43 .70 55 .87 56 .60 50 .42 57 .60 52 .50 Pnyllite-J117-D3 50 .67 33 .09 54 .67 60 .56 40 .50 48 .78 Page 178 Structural seology of Part of the Crooked Lake Area. Quesnel Highlands, Br i t ish Coluwbia APPENDIX D Stereophotos of var ious fea tu res a t Crooked Lake P la te 5a. Chl-hnbd-plag m e t a - d i o r i t e w i t h i n t e r l a y e r e d / i n t e r f o l d e d q t z - c h l s c h i s t ( A n t l e r ) {DIR-325,L0C-RZ3} P la te 5b. Cross- f rac tu red ch l -hnbd-p lag m e t a - d i o r i t e ; f r a c t u r e s f i l l e d w i t h epidote, quar tz , and magneti te ( A n t l e r ) {DIR-335, L0C-RZ3} Page 179 Structural ecology of Part of the Crooked Lake Area, Quesnel Highlands. British Colunbia Pla te 5c. Qtz-chl -hnbd s c h i s t w i t h i n t e r l a y e r s o f q tz -p lag-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} P la te 5d. Red sandstone conta ined 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 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 Pla te 5 f . Phase one i s o c l i n e o f chl-hnbd s c h i s t and q tz -p lag-ep meta-wacke ( A n t l e r ) {DIR-350, L0C-RZ6} P la te 5g. 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 (Snowshoe) {DIR-320, L0C-RZ8} Page 182 Structural ecology of Part of the Crooked Lake Area. Quesnel Highlands. British Colunbla Pla te 5h. Upr ight phase two medium 'c lockwise-vergence ' f o l d i n ch l -p lag-hnbd s c h i s t ; note poss ib le t i g h t f o l d forms invo lved i n upper hinge of f o l d ( A n t l e r ) {DIR-335, L0C-RZ5} P la te 5 i . Upr ight 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 i n 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. Br i t ish Colunbia Structural Geology of Part of the Crooked Lake Area, Quesnel Highlands, Br i t ish Columbia P la te 5k. Recumbent t i g h t phase two f o l d re fo lded by up r i gh t phase th ree medium f o l d (Eureka Q u a r t z i t e ) {DIR-315,L0C-J104} P la te 51 . Upr ight steep p lunging 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 

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