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Geology of the Haggart Creek-Dublin Gulch Area, Mayo district, Yukon Territory. Tempelman-Kluit, Dirk Jacob 1964

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GEOLOGY OF THE HAGGART CREEK -DUBLIN GULCH AREA Mayo D i s t r i c t , Yukon T e r r i t o r y DIRK JACOB TEMPELMAN-KLUIT B.A.Sc, U n i v e r s i t y of B r i t i s h Columbia, 1962. A. THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE i n the Department of GEOLOGICAL ENGINEERING We accept t h i s t h e s i s as conforming to the requ i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA March, 1964 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y of B r i t i s h C o l u m b i a , I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree that p e r -m i s s i o n f o r e x t e n s i v e c o p y i n g of t h i s t h e s i s f o r s c h o l a r l y purposes may b e . g r a n t e d by the Head of my Department or by h i s r e p r e s e n t a t i v e s . I t i s unders tood that , c o p y i n g or p u b l i -c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d without my w r i t t e n p e r m i s s i o n * 0 Department of 7 ^ 7 ^ kAftv"**J The U n i v e r s i t y of B r i t i s h C o l u m b i a , Vancouver 8, Canada Date ABSTRACT The map a r e a i s a f o u r m i l e s by ten m i l e s s t r i p that extends westward from the summit of Potato H i l l s . The centre of the map a r e a l i e s about t h i r t y m i l e s n o r t h of Mayo, Y.T. Exposure i s poor i n many p a r t s of the area, because of the t h i c k P l e i s t o c e n e cover. The rocks i n the area are q u a r t z i t e s of the p r e -cambrian Yukon Group. Q u a r t z i t e i s g e n e r a l l y micaceous and c o n t a i n s interbedded p h y l l i t e . R e g i o n a l metamorphism (green-s c h i s t f a c i e s ) has a f f e c t e d these rocks. An e a r l y bedding plane f o l i a t i o n has been m o d i f i e d by two d i s t i n c t phases of f o l d i n g . A g r a n o d i o r i t e stock with r e l a t e d s i l l s of s i m i l a r composition has i n t r u d e d the metamorphic assemblage and a f i v e hundred f e e t wide thermal metamorphic aureole that c o n t a i n s corundum has been developed i n the metasedimentary rocks around the s t o c k . E a s t t r e n d i n g and l a t e r n o r t h t r e n d i n g f a u l t s have d i s r u p t e d the r o c k s . M i n e r a l i z a t i o n i n the a r e a i s of v a r i o u s types. S i l v e r - l e a d - a n t i m o n y v e i n s occur i n the west. A p r e l i m i n a r y study of t h e i r mineralogy shows them to c o n t a i n jamesonite, galena, s p h a l e r i t e , c h a l c o p y r i t e , p y r i t e , a r s e n o p y r i t e , t e t r a -h e d r i t e and b o u l a n g e r i t e i n a gangue of s i d e r i t e and dolomite. Secondary m i n e r a l s i n c l u d e b i n d h e i m i t e or s t e t e f e l d i t e , angle-s i t e , g o e t h i t e , s c o r o d i t e , c o v e l l i t e and c h a l c o s i t e . Two stages of P l e i s t o c e n e i c e advance have m o d i f i e d the topography,, F r o n t i s p i e c e . Peso S i l v e r Mines Camp and a d i t to number One v e i n c r o s s c u t i n foreground. Galena H i l l i n middle background. Davidson range i n f a r background. Overcast weather i s t y p i c a l f o r the a r e a d u r i n g summer, l o o k i n g s o u theast. CONTENTS Page INTRODUCTION. 1 Lo c a t i o n and Access 2 Physiography, Topography and Climate 2 Previous G e o l o g i c a l Work 3 Acknowledgments 4 Mining H i s t o r y 5 G l a c i a t i o n 6 GEOLOGY OF THE AREA 9 General Statement 9 Metamorphic Rocks 12 Medium to dark grey massive q u a r t z i t e 12 Medium to l i g h t grey massive q u a r t z i t e 14 Green and Maroon P h y l l i t e s . 14 Micaceous Q u a r t z i t e 15 Grey P h y l l i t e 17 Andal u s i t e Hornfels 19 Quartz Diopside Hornf e l s 21 i I n t r u s i v e Rocks 2,4 B i o t i t e Quartz D i o r i t e 24 Petrology 24 St r u c t u r e 32 O r i g i n and Mode of Emplacement 33 Quartz Feldspar Porphyry 3 ^ P o r p h y r i t i c Amygdaloidal Bas a l t 35 Page A u g i t i t e 37 STRUCTURAL GEOLOGY ^0 General Statement 40 Minor S t r u c t u r e s 4l F o l i a t i o n 4l L i n e a t i o n 43 Minor Folds 44 J o i n t s 47 Conclusions 48 Major S t r u c t u r e s 51 Folds 51 F a u l t s 52 a. Haggart Creek F a u l t 53 b. T i n H i l l F a u l t . 5^ c. Black P h y l l i t e F a u l t 5^ d. Rex F a u l t 55 e. F i f t e e n Pup C r o s s f a u l t 56 f. Secret Creek F a u l t 56" g. McGann Creek F a u l t 57 Tectonic H i s t o r y 57 S t r u c t u r a l F i t w i t h Patterns to the South: Some Ideas 58 METAMORPHISM 60 General Statement 60 Regional Metamorphism 6l Thermal Metamorphism.. 62 Metasomatism 67 Page Temperatures and Pressures During Metamorphism.... 67 Age R e l a t i o n s 68 ANTIMONY SILVER LEAD .VEINS 69 General Statement 69 Number One V e i n 71 Textures 73 Secondary A l t e r a t i o n 76 Paragenesis 77 Temperature of D e p o s i t i o n and C l a s s i f i c a t i o n . . . 78 Number Two V e i n . 78 Textures 79 Secondary A l t e r a t i o n 80 Paragenesis 80 Temperature of D e p o s i t i o n and C l a s s i f i c a t i o n . . . 80 Number Three V e i n 81 Textures 82 Secondary A l t e r a t i o n 83 Paragene s i s 83 Temperature of D e p o s i t i o n a.nd C l a s s i f i c a t i o n . . . 84 Rex V e i n 85 Textures 86 Secondary A l t e r a t i o n 91 Paragenesis 92 Temperature of D e p o s i t i o n and C l a s s i f i c a t i o n . . . 93 Zoning of • the De p o s i t s 9^ Time of Emplacement of V e i n M i n e r a l s .94 SUMMARY OE GEOLOGIC HISTORY 96 ILLUSTRATIONS Facing Figure Page Frontispiece Peso S i l v e r Mines Camp, adit to number One vein crosscut, Galena H i l l and Davidson Range... 1. Index map to show l o c a t i o n and access 2; 2. Looking east up the v a l l e y of Dublin Gulch at Potato H i l l s k 3. Looking east down the v a l l e y of Fisher Gulch at Tin H i l l , Potato H i l l s and Lynx Dome 5 4.. Knot of k a o l i n i t e and limonite surrounded by flakes of muscovite i n massive quartzite 13 5. Micaceous quartzite cut perpendicular to l i n e a -t i o n and f o l i a t i o n 15 6. Folded muscovite bands i n grey p h y l l i t e 18 7. Grey p h y l l i t e cut perpendicular to f o l i a t i o n and l i n e a t i o n . . 18 8. Andalusite hornfels cut perpendicular to f o l i a -t i o n and l i n e a t i o n . . . 19 9. Cross-section of euhedral andalusite c r y s t a l showing the pleochroic core 20 10. Anhedral altered andalusite prism i n andalusite hornfels 20 11. Anhedral grains of corundum i n a groundmass of micas and quartz 21 12. B l u f f s west of Ray Gulch 22 13. Diopside i n quartz 23 14. Quartz Diopside hornfels 23 15. A zoned plagioclase grain 25 16. Porphyritic b i o t i t e quartz monzonite phenocrysts of plagioclase, quartz and b i o t i t e 25 F a c i n g F i g u r e Page 1 7 . Medium g r a i n e d b i o t i t e g r a n o d i o r i t e 26 1 8 . P a r t l y a l t e r e d p o r p h y r i t i c gabbroic b i o t i t e quartz d i o r i t e 2 7 19. P a r t l y a l t e r e d gabbroic b i o t i t e 27 20. S t r o n g l y a l t e r e d gabbroic b i o t i t e quartz d i o r i t e 29 2 1 . F o l i a t i o n a t c o n t a c t of g r a n o d i o r i t e 32 2 2 . Contours on upper s u r f a c e of stock 3 3 23. P o r p h y r i t i c amygdaloidal b a s a l t 36 2 4 . l a r g e phenocryst of i n d i v i d u a l rounded g r a i n s of s a n i d i n e 36 25. G r a i n of d i o p s i d i c a u g i t e 3 7 26. Hornblende i n a u g i t i t e 3 7 2 7 . "Checkerboard" twinning 3 7 2 8 . Phase I minor f o l d s i n micaceous q u a r t z i t e 4 0 29. P o l e s to f o l i a t i o n east o f Haggart Creek 4 2 30. P o l e s to f o l i a t i o n west of Haggart Creek 4 2 31. P o l e s to f o l i a t i o n i n the number One v e i n c r o s s c u t 4 2 32. Phase I l i n e a t i o n and p o l e s to f o l i a t i o n . n o r t h o f Black P h y l l i t e f a u l t 4 3 3 3 * L i n e a t i o n and poles to f o l i a t i o n south of Rex f a u l t 4 3 3 4 . Phase I l i n e a t i o n s west of Haggart Creek f a u l t . . 4 3 35» Phase I l i n e a t i o n s east of Haggart Creek f a u l t . . 4 3 36. Phase I I l i n e a t i o n s west of Haggart Creek f a u l t . 4 3 3 7 • Phase I minor f o l d s n o r t h of McGann Creek 4 4 3 8 , 3 9 » 4 0 . C r o s s - s e c t i o n s of minor f o l d s of Phase I from v a r i o u s p a r t s o f the map area . ... 4 5 4 1 . Phase I f o l d axes west of Haggart Creek f a u l t . . . 4 6 4 2 . P o les to j o i n t s west.of Haggart Creek f a u l t 4 7 Facing Figure ; -• ; • ' Page 43. Poles to j o i n t s east of Haggart Creek f a u l t . . . . 47 44. Poles to j o i n t s i n g r a n i t i c rocks 48 45. ACF diagram f o r g r e e n s c h i s t f a d e s 6 l 46. AKF diagram f o r hornblende h o r n f e l s f a c i e s 63 47. ACF diagram f o r hornblende h o r n f e l s f a c i e s 65 48. Temperature and pressure of thermal metamorph-ism . 68 49. Peso S i l v e r Mines Camp l o o k i n g north 69 50. T e x t u r a l r e l a t i o n s h i p s of p y r i t e 73 51. Two h a b i t s of p y r i t e 73 52. Coarse p r i s m a t i c g r a i n s of jamesonite 74.-53. S i d e r i t e c o n t r o l l e d g o e t h i t e boxworks 77 54. Number One v e i n paragenesis 78 55« Arseno-pyrite i n jamesonite-,-..... 79 56. Number Two v e i n paragenesis 80 57. P y r i t e i n galena 82 58. Number Three v e i n paragenesis 83 59. S p h a l e r i t e i n jamesonite 87 60. . S i d e r i t e f i l l e d f r a c t u r e i n t e t r a h e d r i t e 87 61. Jamesonite and t e t r a h e d r i t e i n contact 88 62. Jamesonite l a t h s enclosed by s i d e r i t e 88 63. Two h a b i t s of jamesonite.... 89 64. Jamesonite and galena i n contact 89 65. Galena i n contact with dolomite 90 66. S i d e r i t e f i l l i n g f r a c t u r e s i n t e t r a h e d r i t e 90 67. A l t e r a t i o n of jamesonite along f r a c t u r e s 91 68. Rex Vein paragenesis 93 APPENDICES APPENDIX I Geologic Map of Haggart Creek - D u b l i n Gulch Area S c a l e 1 " = 1 , 0 0 0 » APPENDIX I I S t r u c t u r a l Trend Map Haggart Creek - D u b l i n Gulch A r e a S c a l e 1 : 5 0 , 0 0 0 APPENDIX I I I Block diagram of Keno H i l l , Mount Haldane, Potato H i l l s Area 1. INTRODUCTION The area near D u b l i n Gulch and S e c r e t Creek has been of economic i n t e r e s t s i n c e the e a r l y p a r t of t h i s c e n t u r y . D u b l i n Gulch and Haggart Creek c o n t a i n p l a c e r g o l d d e p o s i t s . The presence of lode g o l d and tungsten m i n e r a l i z a t i o n on the west s i d e of Potato H i l l s has been known s i n c e the 1 9 2 0 ' s . Recent e x p l o r a t i o n a c t i v i t y west of D u b l i n Gulch on o l d a n t i m o n y - s i l v e r - l e a d showings has aroused new i n t e r e s t i n the a r e a . The o b j e c t of the p r e s e n t work was twofold:: to map the rocks and s t r u c t u r e s i n d e t a i l and thus to provide a g e o l o g i c framework f o r d e t a i l e d s t u d i e s r e q u i r e d i n the f u r t h e r e x p l o r -a t i o n and development of the a n t i m o n y - s i l v e r - l e a d d e p o s i t s ; and to work out the mineralogy of these d e p o s i t s . The a r e a mapped (about kO square m i l e s ) l i e s e a s t of S e c r e t Creek and extends east to Potato H i l l s . I t i s bounded on the south by the V a l l e y of Lynx and Haggart Creeks and ex-tends n o r t h from t h i s boundary about three m i l e s . The w r i t e r spent most of the summer of 1962 and a few weeks of the summer of 1963 i n the a r e a . F i g u r e 1» Index map to show l o c a t i o n and a c c e s s . 2. L o c a t i o n and Access The c e n t r e of the map area l i e s t h i r t y m i l e s n o r t h of Mayo Landing, the n e a r e s t l a r g e s e t t l e m e n t . Access to the western p a r t of the ar e a can he gained by s e v e r a l r o u t e s (see index map). The d i s t a n c e by road to Mayo from the west end of the area i s about f i f t y m i l e s . The area i t s e l f i s now c r i s s - c r o s s e d by a number of b u l l d o z e r t r a i l s . Physiography, Topography and Climate The e n t i r e map area l i e s w i t h i n Stewart P l a t e a u - a s u b d i v i s i o n of Yukon P l a t e a u . The topography of p a r t s o f the Stewart P l a t e a u has been d e s c r i b e d by C a i r n e s (1916) and Bostock (19390 • Of "the Mayo area, C a i r n e s says: "Mayo area i s m a i n l y c h a r a c t e r i z e d by b e i n g s u b d i v i d e d by w e l l developed, f l a t bottomed, I n t e r l o c k i n g v a l l e y s i n t o s m a l l , i s o l a t e d mountain groups and areas of w e l l d i s s e c t e d upland The v a l l e y w a l l s have become smoothed, p l a n a t e d , and steepened, g i v i n g the v a l l e y s t y p i c a l U-shaped c r o s s e c t i o n s . In a d d i t i o n , the f l o o r s of the master v a l l e y s have become deeply covered w i t h g l a c i a l d e t r i t u s , which i n p o s t - g l a c i a l times has been trenched and i n p a r t removed by the streams of the d i s t r i c t . " R e l i e f i s moderate. Most r i d g e s reach e l e v a t i o n s c l o s e to 4,500 f e e t , w h i l e the summit of Potato H i l l s , the h i g h e s t p a r t of the map area, l i e s a t 5>000 f e e t . The v a l l e y s o f the l a r g e creeks l i e at an e l e v a t i o n of about 2,500 f e e t . 3 Large areas of upland are almost f l a t and f e a t u r e l e s s and merge g r a d u a l l y with the st e e p e r , but r e g u l a r v a l l e y w a l l s . Outcrop i s s c a r c e and g l a c i a l t i l l widespread and g e n e r a l l y t h i c k . Abundant outcrop i s found only at the heads of gulches and near the top o f the v a l l e y w a l l s . Some of the s t e e p s i d e d r i d g e s have outcrops along them. The f l a t topped h i l l s are almost devoid of outcrop and are covered by l a r g e areas of d i s i n t e g r a t e d , moss and brush covered, b l o c k s o f bedrock, which resemble felsenmeer. Rocks of the "felsenmeer" are f o r the most p a r t l o c a l l y d e r i v e d . The weather i s q u i t e v a r i a b l e i n summer. A s p e l l of warm weather may change unexpectedly to d r i z z l y c o o l weather t h a t can l a s t f o r days or weeks. The sky seems p e r p e t u a l l y cloudy. D u r i n g the e a r l y summer, d a y l i g h t extends f o r twenty hours of the day: towards the end of summer, d a y l i g h t l a s t s f o r l e s s than t en hours per day. During summer the v a l l e y s are hot, while the h i l l t o p s are c o o l e r . Winters are c o l d and dark, temperatures commonly d i p as low as 6 0°F below z e r o . P r e c i p i -t a t i o n i s l i g h t . P r e v i o u s G e o l o g i c a l Work Although a c o n s i d e r a b l e amount of work has been done i n c o n n e c t i o n w i t h the p l a c e r d e p o s i t s a t D u b l i n Gulch and Haggart F i g u r e 2. L o o k i n g e a s t UP t h e v a l l e y o f D u b l i n G u l c h - a t P o t a t o H i l l s i n b a c k g r o u n d . T a k e n f r o m  T i n H i l l . Th e t o p o g r a p h y i s c h a r a c t e r i s t i c  o f t h e map a r e a . 4. Creek, and the lode gold, t i n and s c h e e l i t e d e p o s i t s near D u b l i n Gulch, n o t h i n g i s p u b l i s h e d c o n c e r n i n g the a n t i m o n y - s i l v e r - l e a d showings west of D u b l i n Gulch. Reference to the above mentioned p l a c e r and lode d e p o s i t s i s made i n v a r i o u s e a r l y Summary Reports of the G.S.C. by D.D.Cairnes, W.E.Cockfield and H.S.Bostock. H.S.Bostock mapped the are a i n the v i c i n i t y of Potato H i l l s and D u b l i n Gulch at a s c a l e of 2 , 0 0 0 ' = 1 " d u r i n g the summer of 19^ 3 . A c o n s i d e r a b l e amount of i n f o r m a t i o n on the s i l v e r -lead-antimony m i n e r a l i z a t i o n west of Haggart Creek i s contained i n unpublished m i n e r a l o g r a p h i c r e p o r t s done under the d i r e c t i o n of Prof.R.M.Thompson by J.A.Coates ( i 9 6 0 ) , D.Tempelman-Kluit ( 1 9 6 2 ) and A.Armour-Brown ( 1 9 6 3 ) . Acknowledgements The w r i t e r was very a b l y and w i l l i n g l y a s s i s t e d i n the f i e l d by Fred A. C a r t e r and Jim R. McMahon. I am inde b t e d to Dr. .A.E.Aho, C o n s u l t i n g G e o l o g i c a l Engineer, f o r h i s i n t e r e s t , h e l p and guidance dur i n g the f i e l d work and throughout the p r e p a r a t i o n of t h i s t h e s i s . I f u r t h e r wish to express s i n c e r e a p p r e c i a t i o n to P r o f e s s o r K.C.McTaggart, under whose d i r e c t i o n t h i s t h e s i s was w r i t t e n , and to P r o f e s s o r R.M.Thompson f o r h i s advice, and he l p w i t h the m i n e r a l o g i c a l work. Figure 3. Looking east down the v a l l e y of F i s h e r Gulch at T i n H i l l i n middle foreground, Potato H i l l s  i n r i g h t "background and Lynx Dome i n l e f t  background. The topography i s t y p i c a l of that  found i n most of the map area. 5. The c o n t i n u e d i n t e r e s t and g o o d w i l l of the personnel of Peso S i l v e r Mines L t d . i s v e r y much a p p r e c i a t e d . Peso S i l v e r Mines generously defrayed the c o s t of some of the t h i n s e c t i o n s , photographs, t h e s i s t y p i n g and draughting of the map. Min i n g H i s t o r y The i n i t i a l d i s c o v e r y of g o l d on Haggart Creek was d e s c r i b e d by C a i r n e s (1915) who says: "Gold i s r e p o r t e d to have been f i r s t found on Haggart Creek i n 1895 and i n I896 the creek i s known to have been p r o s -pected by Thomas Nelson who found gold i n the canyon f o u r to f o u r and one h a l f m i l e s from the mouth; a f t e r him the stream was named NelsonCreek. In the same year Thomas Haggart b u i l t two c abins on the creek, and one on D u b l i n Gulch, from which to prospect and mine. In 1898 Thomas Haggart, Thomas Nelson, P e t e r Haggart and Warren H i a t t s t a r t e d from Dawson f o r Nelson Creek, but enroute separated i n t o two p a r t i e s , and P e t e r Haggart and Warren H i a t t , r e a c h i n g t h e i r d e s t i n a t i o n f i r s t , staked D i s c o v e r y , and renamed the stream a f t e r P e t e r Haggart. Since then there has each year been more or l e s s mining and p r o s p e c t i n g along the creek." P l a c e r mining on Haggart Creek has continued i n t e r -m i t t e n t l y s i n c e 1895 and i s s t i l l c a r r i e d on to-day. A peak of a c t i v i t y was reached i n 1915 when seventeen men worked on the creek i n f o u r separate p a r t i e s . John S u t t l e s , who h e l d about twenty f i v e hundred f e e t near the mouth of D u b l i n Gulch from I898 to 1915, i s supposed to 6. have recovered upwards of $45,000 worth of g o l d during t h a t time. The C a n t i n b r o t h e r s ( L o u i s and Prank) a c q u i r e d S u t t i e s ' ground i n the f a l l o f 1915 and continued to mine the creek u n t i l the 1920's, when i n t e r e s t waned and the ground l a y i d l e . Not u n t i l 1916 was the value of the s c h e e l i t e which was p i c k e d up i n the p l a c e r concentrates r e a l i z e d and s i n c e t h i s time the s c h e e l i t e has been saved and shipped. In 1936 Ed Barker and George P o t t e r staked Haggart Creek below D u b l i n Gulch, w h i l e Fred T a y l o r staked the f i r s t m i l e of D u b l i n Gulch and E. B l e i l e r and H. Seaholm staked above T a y l o r . Fred T a y l o r s t i l l works h i s ground on D u b l i n Gulch. In the e a r l i e r years of p l a c e r mining c o n s i d e r a b l e p r o s p e c t i n g f o r the lode source of the p l a c e r g o l d l e d to the d i s c o v e r y of a number of s m a l l , s t r o n g l y o x i d i z e d , g o l d b e a r i n g a r s e n o p y r i t e v e i n s . A c o n s i d e r a b l e amount of work (mainly i n the form of d r i f t s ) was done on some of these v e i n s before 1918. No shipments were ever made from any of these showings. Most workings are now caved or f u l l o f i c e . G l a c i a t i o n The g l a c i a l f e a t u r e s and h i s t o r y o f the area have been b r i e f l y d e s c r i b e d by Bostock (1939) (1943) (1947) and C a i r n e s 7 (1915) (1916), McTaggart ( i 9 6 0 ) . Bostock (1943) c o n s i d e r s that "the map area occupies p a r t of a d i s t r i c t i n which the g l a c i e r s formed d u r i n g the l a s t , main stage of P l e i s t o c e n e g l a c i a t i o n wasted away D u b l i n Gulch and Haggart Creek are b e l i e v e d t o have been p r o t e c t e d from t h i s l a s t g l a c i a l advance by the h i l l s to the eas t , but there i s e v i -dence i n D u b l i n Gulch of an e a r l i e r stage of P l e i s t o c e n e g l a c i a -t i o n d u r i n g which the i c e rose much h i g h e r than d u r i n g the l a s t stage." The evidence s u p p o r t i n g the f i r s t statement i s i n the form of t i l l banks, scour marks, drumlins, kame t e r r a c e s and outwash f e a t u r e s , the d i s p o s i t i o n of which suggest t h a t the upper l i m i t of the l a s t stage of P l e i s t o c e n e g l a c i a t i o n dropped o f f r a p i d l y i n t h i s area which must have been c l o s e to the margin of maximum south westward advance of i c e of the l a s t P l e i s t o c e n e p e r i o d . Evidence f o r the second statement concerning an e a r l i e r stage of i c e advance d u r i n g the P l e i s t o c e n e i s found i n the v a l l e y of D u b l i n Gulch. Here a w e l l developed, two f e e t t h i c k s o i l mantles a t h i c k l a y e r of t i l l , which c o n t a i n s many weathered and crumbly f o r e i g n rocks and some s t r i a t e d a n d e s i t i c b o u l d e r s . A weathered t i l l and w e l l developed s o i l are not found a s s o c i a t e d w i t h the l a s t stage of g l a c i a t i o n and hence these phenomena are thought to i n d i c a t e t h a t g l a c i a t i o n i n t h i s area o c c u r r e d e a r l i e r i n the P l e i s t o c e n e than t h a t whose f r e s h d e b r i s occurs i n McQuesten v a l l e y to the south. 8 Evidence t h a t the o l d e r g l a c i a l advance covered the area west of D u b l i n Gulch i s scanty. G l a c i a l s t r i a e a t an e l e v a t i o n of f o u r thousand f e e t on the r i d g e n o r t h of C a r t e r Creek are thought to belong to the o l d e r g l a c i a l stage. A few e r r a t i c s , mostly o f d i o r i t e are s c a t t e r e d across the ar e a . In some p l a c e s a w e l l developed s o i l , as much as two f e e t t h i c k , i s found o v e r l y i n g a weathered t i l l . In g e n e r a l topographic evidence f o r the e a r l y g l a c i a l stage i s l a c k i n g , whereas i t i s qu i t e w e l l preserved f o r the l a t e r g l a c i a l advance. McTaggart ( i 9 6 0 ) has suggested t h a t t h i s d i f f e r e n c e i n the s t a t e o f p r e s e r v a t i o n of topographic f e a t u r e s i s due to a lo n g time i n t e r v a l between the two g l a c i a l e p i sodes. While the v a l l e y s of Haggart Creek and D u b l i n Gulch show no signs of ha v i n g been invaded by i c e du r i n g the l a s t g l a c i a l advance ( s i n c e none of the f e a t u r e s a s s o c i a t e d with the l a s t stage of g l a c i a t i o n i s present, and s i n c e a s o i l , which would probably have been removed by l a t e r g l a c i a l s c o u r i n g i s found i n D u b l i n Gulch) the v a l l e y o f S e c r e t Creek to the west does have a kame t e r r a c e on p a r t s of i t s west bank and i t i s thought t h a t a s u b s i d i a r y i c e tongue may have l a i n i n i t s v a l l e y . Permafrost i s not r e s t r i c t e d to the nort h d i p p i n g s l o p e s , although i t i s encountered nearer to the s u r f a c e here 9. than i t i s on the southern s l o p e s . The depth to which perma-f r o s t extends i s not known with much c e r t a i n t y i n t h i s area, but u n frozen ground has not been reached a t a depth of one hundred and f i f t y f e e t i n underground workings. On Keno and Galena H i l l s , permafrost extends to depths of two hundred to f o u r hundred f e e t . Stone s t r i p e s and rock polygons are found o n l y on the f l a t top of Potato H i l l s and even here they are p o o r l y developed. GEOLOGY OP THE AREA GENERAL STATEMENT A t h i c k sequence of weakly metamorphosed, n o n - f o s s i l i -f e r o u s , sedimentary rocks u n d e r l i e s the map area. The sequence i s s a i d to be of Precambrian and/or Cambrian age (Green 19&2) and belongs to Bostock's Yukon Group. S t r a t i g r a p h i c tops were not determined w i t h i n the map area so t h a t r e l a t i v e ages are not known. Beds appear to be younger i n the n o r t h than i n the south. The metamorphic sequence has been i n t r u d e d by g r a n o d i o r i t i c rocks Mesozoic, perhaps Cretaceous age (Green 1962) and by b a s a l t i c rocks of T e r t i a r y age. Cemented g r a v e l of T e r t i a r y age occurs near the bottom of some v a l l e y s . Quarternary u n c o n s o l i d a t e d g l a c i a l and a l l u v i a l d e p o s i t s mantle the h i l l s i d e s to e l e v a t i o n s of t h i r t y -10 f i v e hundred feet. The following table shows these r e l a t i o n -ships more c l e a r l y . ERA PERIOD LITHOLOGY Quarternary Unconsolidated g l a c i a l and a l l u v i a l deposits CENOZOIC Tertiary Cemented gravel - unconsolidated •Porphyritic amygdaloidal basalt MESOZOIC Cretaceous Quartz and/or feldspar porphyry Medium grained b i o t i t e granodiorite Precambrian and/or Cambrian Micaceous quartzites, p h y l l i t e s , massive feldspathic quartzites. YUKON GROUP The present study concerns the Yukon group. Although the Yukon group has been known f o r many years and i s widely di s t r i b u t e d i n central Yukon, l i t t l e i s known of i t s i n t e r n a l stratigraphy, because i t i s s t r u c t u r a l l y complex and crops out poorly. A description of the structural sequence i s resorted to since the stratigraphic succession i s not known. The following succession of metamorphic rocks from north (youngest) to south (oldest) has been established. 1. Massive grey quartzite - generally, thought not univ e r s a l l y s l i g h t l y feldspathic - with black carbonaceous p h y l l i t e and minor interbedded black i n pure limestone. 11 I n the south of the map a r e a are s i m i l a r q u a r t z i t e s t h a t c o n t a i n interbedded green and maroon p h y l l i t e , which are thought to be the u p f a u l t e d c o r r e l a t i v e of t h i s u n i t on the b a s i s of s i m i l a r l i t h o l o g y . 2. Micaceous q u a r t z i t e w i t h interbedded grey p h y l l i t e . 3• P h y l l i t i c q u a r t z i t e w i t h interbedded a n d a l u s i t e h o r n -f e l s (metamorphosed e q u i v a l e n t of grey p h y l l i t e ) , quartz d i o p -s i d e h o r n f e l s and quartz d i o p s i d e skarn (metamorphosed equiva-l e n t s of impure limestone) and marble. On the b a s i s of s i m i l a r l i t h o l o g y , the lower or l a s t u n i t i s considered to be the c o r r e l a t i v e of the Upper S c h i s t on Keno and Galena H i l l s . The map area i s d i v i d e d i n t o an e a s t e r n and a western p a r t by the n o r t h t r e n d i n g Haggart Creek f a u l t . E a s t of t h i s f a u l t are the lowest rocks which dip moderately to the northwest. Rocks i n t h i s h a l f of the map area have been a f f e c t e d by c o n t a c t metamorphism. S t r u c t u r a l f e a t u r e s i n the e a s t e r n p a r t i n d i c a t e t h a t the t e c t o n i c h i s t o r y has been s i m i l a r to t h a t i n the west. West of Haggart Creek f a u l t are the h i g h e s t r o c k s . Dips here are to the n o r t h e a s t a t moderate to shallow a n g l e s . Only weak r e g i o n a l metamorphism has a f f e c t e d these r o c k s . The rocks i n the east b l o c k can be d i v i d e d i n t o two 12 major groups whose contact i s apparently conformable. In the southeast corner of the area are q u a r t z i t e s w i t h limey i n t e r b e d s , while the rocks i n the northwest corner of t h i s block are non-calcareous q u a r t z i t e s and p h y l l i t e s . The block has been intruded by a g r a n o d i o r i t e stock which occupies i t s center. Thermalmetamor-phism has a f f e c t e d the rocks near the g r a n o d i o r i t e c o n t a c t . f The western block can be d i v i d e d i n t o three roughly east-west areas on the ba s i s of l i t h o l o g y . The northernmost of these areas i s made up of f a i r l y massive grey f e l d s p a t h i c quart-z i t e . The middle area c o n s i s t s of micaceous q u a r t z i t e s and I p h y l l i t e s . The contact between the northernmost bands i s con- j formable i n the west and unconformable i n the east. The southern area i s separated by the northern ones by a f a u l t . Rocks i n the southern band are micaceous, f e l d s p a t h i c q u a r t z i t e s and p h y l l i t e s . I n t r u s i v e rocks i n t h i s block are l i m i t e d to s i l l s of d i o r i t e r e -l a t e d to the stock i n the east block and dykes of quartz f e l d s p a r porphyry as w e l l as p o r p h y r i t i c b a s a l t . METAMORPHIC ROCKS Medium to dark grey massive q u a r t z i t e Grey q u a r t z i t e crops out south of Rex f a u l t and west of Haggart Creek f a u l t . Maroon and green p h y l l i t e s and p h y l l i t i c q u a r t z i t e s described s e p a r a t e l y occur interbedded w i t h i t . F i g u r e 4, K n o t o f k a o l i n i t e a n d l i m o n i t e s u r r o u n d e d b y f l a k e s o f m u s c o v i t e i n m a s s i v e q u a r t z i t e  X - H i c o l s . x ^5. 1 3 Q u a r t z i t e outcrops are w e l l j o i n t e d but g e n e r a l l y show a poor f o l i a t i o n and l i n e a t i o n . The q u a r t z i t e i s medium grey i n c o l o u r and has a ' s i l i c e o u s ' l o o k . Much of i t i s studded with equant white g r a i n s of k a o l i n i z e d f e l d s p a r up to 5 mm. a c r o s s . The rock c o n t a i n s more than 90$ quartz and about 5$ muscovite, w h i l e k a o l i n , l i m o n i t e and s c h o r l i t e make up the remainder. G r a i n s i z e i s uniform and about . 2;.:mm., the o v e r a l l t e x t u r e i s d i s t i n c t l y g r a n o b l i s t i c . Quartz occurs i n very i r r e g u l a r l y shaped g r a i n s , which have a poor p r e f e r r e d form o r i e n t a t i o n p a r a l l e l to f o l i a t i o n . The quartz shows s t r o n g l a m e l l a r and i r r e g u l a r e x t i n c t i o n . A small p r o p o r t i o n (5) of l a r g e g r a i n s (4 mm.) of quartz of v a r i o u s roughly equant shapes are s c a t t e r e d randomly through the rock. Muscovite f l a k e s occur s c a t t e r e d through the rock and segregated i n t h i n l a y e r s t h a t d e f i n e the f o l i a t i o n . Roughly equant knots or aggregates of very f i n e g r a i n e d k a o l i n i t e (checked by X-ray powder method) and l i m i n i t e knots are about 2 mm. acr o s s and commonly have muscovite f l a k e s surround-i n g them. S c h o r l i t e i s i n anhedral g r a i n s s c a t t e r e d evenly through the rock. 14 Medium to l i g h t grey massive q u a r t z i t e The massive q u a r t z i t e s i n the n o r t h e r n p a r t of the map area are s i m i l a r to those which occur i n the south. Northern grey q u a r t z i t e s are darker i n c o l o u r than are southern grey q u a r t z i t e s . P h y l l i t i e i n t e r b e d s are l e s s p l e n t i f u l i n the no r t h e r n q u a r t z i t e than they are i n the south and they are bl a c k i n c o n t r a s t to the green and maroon c o l o u r s o f interbedded phy-l l i t e s i n the south. In t h i n s e c t i o n such b l a c k p h y l l i t e s are marked by t h e i r carbon c o n t e n t . A few t h i n d i s c o n t i n u o u s i n t e r b e d s of black, carbon-aceous and micaceous limestone occur i n the black p h y l l i t e s . Green and maroon p h y l l i t e s Green and maroon p h y l l i t e s make up a small p a r t of the exposed southern grey q u a r t z i t e u n i t but are p a r t i c u l a r l y prominent i n the v i c i n i t y of Rex v e i n . This rock type cannot be d i s t i n g u i s h e d m i c r o s c o p i c a l l y from grey p h y l l i t e . A d i s t i n c t i o n can be made i n the f i e l d on the b a s i s of the c o l o u r of the rock. Some of the p h y l l i t e s have a f u c h s i t e green c o l o u r and i n these the mica has a r e f r a c t i v e index n„ = 1.575 (n„ i s y z very c l o s e to t h i s value) and 2V - 4 9 ° . These p r o p e r t i e s f i t f o r muscovite proper. The green c o l o u r i s c o n s i d e r e d due to the F i g u r e 5» M i c a c e o u s q u a r t z i t e c u t p e r p e n d i c u l a r t o l i n e a t i o n a n d f o l i a t i o n , s h o w i n g weak l a y e r i n g  a n d r a n d o m o r i e n t a t i o n o f m u s c o v i t e i n q u a r t z .  1 - N i c o l . x 4 5 . 15. chromium content of these micas, which was detected i n a qu a l i -tative spectrographic analysis. Other p h y l l i t e s have a brownish red or maroon colour. The mica i n these rocks has ny = 1 . 5 7 4 and 2V = 4 5 ; properties that f i t well f o r muscovite. Micaceous quartzite Micaceous quartzites underlie much of the map area. An eastward, trending layer of micaceous quartzite crops out west of Haggart Creek f a u l t and continues and swings north-eastward east of the f a u l t without much apparent change i n thickness. Thin layers of p h y l l i t i c rocks, too discontinuous to be mapped, l o c a l l y p l e n t i f u l i n the micaceous quartzites, are described elsewhere. P h y l l i t i c rocks make up less than a quarter of the micaceous quartzite map unit and are commoner i n the west than i n the east. Many outcrops of the quartzite exhibit well developed j o i n t i n g . A good f o l i a t i o n , due to very c l o s e l y spaced micaceous and p h y l l i t i c partings, i s nearly universal and l i n e a t i o n i s gen-e r a l l y well developed on the micaceous partings. The quartzite varies i n colour from almost white, through l i g h t grey and d u l l greenish grey to l i g h t brownish, d u l l greenish grey being i t s commonest colour. Weathered rocks are reddish brown to black. Micas weather l i g h t golden brown. 16. • A very common f e a t u r e o f the q u a r t z i t e s are l e n s e s , pods, and i r r e g u l a r masses of white qu a r t z . These l e n s e s gen-e r a l l y l i e i n the f o l i a t i o n plane and var y i n s i z e from a few inches i n diameter and a f r a c t i o n of an i n c h i n t h i c k n e s s , to s e v e r a l f e e t or even tens of f e e t across and thi c k n e s s e s of a f o o t o r two. The quartz masses are commonly i r r e g u l a r l y f o l d e d and are e s p e c i a l l y common i n the a x i a l p a r t s of minor f o l d s . In t h i n s e c t i o n the quartz shows a very d e f i n i t e p r e f e r r e d op-t i c a l o r i e n t a t i o n . A few f l a k e s o f muscovite are the only im-p u r i t i e s i n the quartz l e n s e s . In t h i n s e c t i o n the micaceous q u a r t z i t e s are seen to c o n s i s t o f : 70$ Quartz 25$ Muscovite and P e n n i n i t e 5$ A l b i t e The p r o p o r t i o n of muscovite to p e n n i n i t e v a r i e s from 4:1 to 2:1. Common minor c o n s t i t u e n t s are s c h o r l i t e and l i m o n i t e . Z i r c o n i s an uncommon minor c o n s t i t u e n t . Quartz g r a i n s are u s u a l l y roughly equant to somewhat e l l i p s o i d a l . Quartz g r a i n s are commonly .1 mm. ac r o s s , but vary from .04 to . 3 mm. a c r o s s . E l l i p s o i d a l g r a i n s have w e l l d e f i n e d p r e f e r r e d form o r i e n t a t i o n p a r a l l e l to the main l i n e a -t i o n . No o p t i c a l p r e f e r r e d o r i e n t a t i o n i s obvious i n such roc k s . Quartz g e n e r a l l y shows wavy or s t r a i n e d e x t i n c t i o n l a m e l l a e 1 7 . (Boehm l a m e l l a e ) t h a t are commonly p e r p e n d i c u l a r to the f o l i a t i o n . Boundaries between quartz g r a i n s are sharp and i r r e g u l a r . No o r i g i n a l g r a i n o u t l i n e s are e v i d e n t . Muscovite, the other common c o n s t i t u e n t , occurs i n t h i n bent f l a k e s and i n aggregates of small f l a k e s . M icas are g e n e r a l l y segregated i n d i s c o n t i n u o u s , i l l d e f i n e d bands. B i o t i t e i s present i n s m a l l amounts i n a few s e c t i o n s of macaceous q u a r t z i t e . Grey P h y l l i t e P h y l l i t e occurs i n micaceous q u a r t z i t e both e a s t and west of Haggart Creek f a u l t , though i t i s more common west of the f a u l t . T h i s rock type occurs i n mappable l a y e r s and a l s o i n , t h i n , d i s c o n t i n u o u s l a y e r s i n the micaceous q u a r t z i t e of which i t may make up as much as 2 5 $ . The rock, which does not crop out i n many p l a c e s , i s a w e l l f o l i a t e d , w e l l l i n e a t e d rock. Fresh s u r f a c e s are medium grey w i t h a d i s t i n c t i v e g r e e n i s h t i n g e , but weathered s u r f a c e s are brownish or golden. Lenses of quartz, d e s c r i b e d p r e v i o u s l y , are a common f e a t u r e of these r o c k s . Thin s e c t i o n s of the p h y l l i t e show a f a i r l y uniform F i g u r e 7 . G r e y p h y l l i t e c u t p e r p e n d i c u l a r t o f o l i a t i o n  a n d l i n e a t i o n , s h o w i n g d o m i n a n t l e p i d o b l a s t i c  t e x t u r e a n d v a r i a t i o n i n g r a i n s i z e . X - N i c o l s . x 4 5 . 18 m i n e r a l o g i c a l composition which i s giv e n below. The rock i s very s i m i l a r to micaceous q u a r t z i t e except t h a t i t c o n t a i n s a h i g h e r p r o p o r t i o n of micas. Quartz kOfo Muscovite 35$ C h l o r i t e 20$ Minor c o n s t i t u e n t s are p l a g i o c l a s e (low An), l i m o n i t e , s c h o r l i t e , b i o t i t e and z i r c o n . The g r a i n s i z e i s about .2 mm. Quartz g e n e r a l l y shows s t r a i n l a m e l l a e p e r p e n d i c u l a r to the f o l i a t i o n . Some quartz g r a i n s are e l l i p s o i d a l . Boundaries between quartz g r a i n s are i r r e g u l a r and d i s t i n c t . No o r i g i n a l d e t r i t a l g r a i n s were seen; most quartz l o o k s r e c r y s t a l l i z e d . Muscovite and c h l o r i t e occur i n t h i n , t a b u l a r f l a k e s and aggregates of such f l a k e s t h a t are o r i e n t e d s u b p a r a l l e l to the f o l i a t i o n . S e g r e g a t i o n of micas i n t o l a y e r s i s f a i r l y common but the l a y e r s are p o o r l y d e f i n e d and d i s c o n t i n u o u s . C h l o r i t e shows ' b e r l i n b l u e ' anomalous b i r e f r i n g e n c e c o l o u r s and i s pro-bably the p e n n i n i t e v a r i e t y . The p r o p e r t i e s of muscovite are 2V=25°, n y=1.587 and i t i s prob a b l y c l o s e to p i c r o p h e n g i t e i n composition. P l a g i o c l a s e shows a l b i t e twinning and occurs i n anhedral, f r e s h g r a i n s . F i g u r e 8. A n d a l u s i t e h o r n f e l s c u t p e r p e n d i c u l a r t o  f o l i a t i o n a n d l i n e a t i o n s h o w i n g s e g r e g a t i o n  i n t o q u a r t z r i c h a n d m i c a r i c h l a y e r s . No  a n d a l u s i t e i n p h o t o g r a p h . X - N i c o l s . x 15. 19 A n d a l u s i t e h o r n f e l s A n d a l u s i t e h o r n f e l s crops out around the quartz d i o r i t e stock e a s t of Haggart Creek f a u l t . The reader i s r e f e r r e d to the accompanying g e o l o g i c map f o r i t s d i s t r i -b u t i o n . The rock does not crop out w e l l even on the r i d g e s and the best specimens occur as f l o a t . F o l i a t i o n has been i n p a r t destroyed by metamorphism. R e l i c t l a y e r i n g c o i n c i d e s w i t h f o l i a t i o n . The rock has a d i s t i n c t i v e d u l l , medium to dark grey c o l o u r w i t h a p u r p l i s h t i n g e on the f r e s h s u r f a c e ; i t weathers golden brownish. A n d a l u s i t e prisms up to an i n c h i n l e n g t h stand i n r e l i e f on weathered s u r f a c e s . T h i n s e c t i o n s show t h a t the rock i s made up of a l -t e r n a t i n g mica r i c h and quartz r i c h l a y e r s of about equal t h i c k n e s s (3 mm.), which have sharp c o n t a c t s . The mineralogy and g r a i n s i z e o f the two types o f l a y e r s i s giv e n below. MICA RICH LAYERS QUARTZ RICH LAYERS MINERALOGY MODE($) GRAIN SIZE (mm) MODE (°/o) GRAIN SIZE (mm) Quartz 20 0.1 80 0.2 B i o t i t e 25 0.2 10 0.1 Muscovite 30 0.2 10 0.1 A n d a l u s i t e 25 2. — — Figure 9. C r o s s - s e c t i o n of euhedral a n d a l u s i t e c r y s t a l  showing the p l e o c h r o i c core. Groundmass  c o n s i s t s of quartz and micas. X - N i c o l s . x 1 5 , Figure 10 Anhedral a l t e r e d a n d a l u s i t e prism i n a n d a l u s i t e  h o r n f e l s . X - H i c o l s . x 15. 20 • In some t h i n s e c t i o n s corundum, c o r d i e r i t e , c h l o r i t e , p l a g i o c l a s e and s i l l i m a n i t e comprise up to 20$ of the r o c k . U n i v e r s a l minor c o n s t i t u e n t s of the rock are s c h o r l i t e , l i m o n -i t e and z i r c o n . An i n t e r e s t i n g f e a t u r e of the rock i s the b i o t i t e i t c o n t a i n s . In the quartz r i c h l a y e r s b i o t i t e i s pleochroism i n greens, while the b i o t i t e of the mica r i c h l a y e r s has a p l e o -e h r o i e scheme i n browns. Muscovite, 27=30°, n y =1.577, i s near the p i c r o p h e n g i t e end of the muscovite s e r i e s . In some t h i n s e c t i o n s a n d a l u s i t e i s i n euhedral, v e r y f r e s h , u n a l t e r e d g r a i n s which have p l e o c h r o i c cores that show the f o l l o w i n g scheme. c = X - p i n k i s h orange a-b = Z-Y - very f a i n t y ellow green In other t h i n s e c t i o n s the a n d a l u s i t e are subhedral and show no pleochroism; i n these i t i s f u l l of f l a k e s of muscovite that l e n d i t a p o i k i l o b l a s t i c t e x t u r e . The occurrence of corundum i n some of these r o c k s warrants s p e c i a l mention. The m i n e r a l has s t r o n g pleochroism i n p u r p l e and green b l u e s . I t i s l a r g e l y r e s t r i c t e d to the micaceous l a y e r s i n the rock and i s more p l e n t i f u l i n rocks c l o s e to the gran-F i g u r e 1 1 . Anhedral g r a i n s of corundum ( h i g h r e l i e f ) i n a groundmass of micas and q u a r t z . 1 - N i c o l . x 45. 2 1 i t i c contact. The mineral occurs as small fractured, anhedral, equant grains and i n aggregates of such grains that are gener-a l l y enclosed i n muscovite. Quartz i n these rocks occurs as fresh, equant grains with i r r e g u l a r , sharp boundaries and uniform extinction. No strong preferred o p t i c a l orientation i s evident upon casual examination. The o v e r a l l texture of these rocks i s t y p i c a l l y granoblastic. Interbedded with andalusite hornfels are p h y l l i t i c quartzites which contain a la r g e r proportion of quartz than the andalusite hornfels, but which are otherwise i d e n t i c a l . The rock i s made up of quartz layers about 5 mm. thick which are separated by p h y l l i t i c partings less than . 2 mm1*;- thick. Near the granodiorite contact the p h y l l i t i c partings contain andalusite. Quartz diopside hornfels This diagnostic rock occurs i n the south eastern corner of the map area. Andalusite hornfels, p h y l l i t i c quart-z i t e , skarn and marble are interbedded with i t . Outcrops of quartz diopside hornfels form the steep b l u f f s of Ray Gulch and other creeks that flow southward into F i g u r e 1 2 . B l u f f s west of Ray Gulch provide good exposures  of a n d a l u s i t e h o r n f e l s , quartz d i o p s i d e h o r n f e l s  and interbedded micaceous q u a r t z i t e . Outcrop  i s poorer than t h i s i n a l l other parts of the  map area. 22 Lynx Creek. The rock i s w e l l j o i n t e d and has a w e l l d e f i n e d l a y e r i n g . A l t e r n a t i n g l a y e r s are green ( d i o p s i d e r i c h ) and white (quartz r i c h ) and are about 5  mm' t h i c k . In t h i n s e c t i o n s i t i s c l e a r t h a t the l a y e r i n g of the rock i s a r e f l e c t i o n of i t s composition. GREEN BANDS W HITE BANDS MINERALS M0DE($) GRAIN SIZE(mm.) M0DE($) GRAIN SIZE(mm.) Quartz 10 .3 ' 50 .1 , D i o p s i d e 65 .5 15 .2 C a l c i t e 5 10 5 10 A c t i n o l i t e 10 5 B i o t i t e 5 .2 10 .2 Minor c o n s t i t u e n t s p r e s e n t i n most s e c t i o n s examined are z i r c o n , corundum, opaques, s c h o r l i t e and sphene. In some s e c t i o n s the minor c o n s t i t u e n t s are more p l e n t i f u l i n the green l a y e r s , while i n others they are c o n f i n e d to the white l a y e r s . In most s e c t i o n s s m a l l amounts of epid o t e , c h l o r i t e , p l a g i o -c l a s e and muscovite are a l s o p r e s e n t . One s e c t i o n c o n t a i n s about t w e n t y - f i v e percent c l i n o z o i s i t e , which i s c o n f i n e d l a r g e l y to green l a y e r s . O v e r a l l t e x t u r e of the rocks I s l a y e r e d , the c o n t a c t s between l a y e r s are sharp. W i t h i n i n d i v i d u a l l a y e r s the te x t u r e i s g r a n o b l a s t i c . G r a i n s i z e of these rocks i s somewhat v a r i a b l e ; most of the m i n e r a l s occur i n equant, subhedral to anhedral g r a i n s . A tendency f o r the green l a y e r s to be of somewhat F i g u r e 13. D i o p s i d e i n q u a r t z : the t y p i c a l a s s o c i a t i o n  i n green bands of quartz d i o p s i d e h o r n f e l s .  1-I'Iicol. x 15. Fi g u r e Ik. Quartz d i o p s i d e h o r n f e l s . M i n e r a l s are c a l c i t e ( c )  d i o p s i d e (d) quartz (q) and a c t i n i l i t e ( a ) . Note  the rough l a y e r i n g . 1-NicoI. x 15. 23 c o a r s e r g r a i n s i z e than the white l a y e r s i s f a i r l y g e n e r a l . The c l i n o p y r o x e n e i n the rock has "been s t u d i e d i n some d e t a i l . I t s c o l o u r i s pale green and no pleochroism was noted. In c r o s s s e c t i o n s p e r p e n d i c u l a r to 'c' the min-e r a l shows w e l l d e f i n e d p a r t i n g on (100) c h a r a c t e r i s t i c of d i a l l a g e . The m i n e r a l i s b i a x i a l + ve: 2V of f i v e g r a i n s i n each s e c t i o n was measured and averaged. The r e s u l t i n g angles f o r the f i v e s e c t i o n s measured are 58) 57» 56, 55 and 53 degrees. In i n d i v i d u a l s e c t i o n s the pyroxene showed a v a r i a -t i o n of 2V of about 2° on e i t h e r s i d e of the average (somewhat l e s s than the v a r i a t i o n of 2V between d i f f e r e n t specimens). The r e f r a c t i v e index n-y f o r the pyroxene was a l s o measured f o r each rock i n which 2V was measured. Only s l i g h t v a r i a t i o n e x i s t s and an average of 1.681 - .004 was obtained. B i r e -f r i n g e n c e averages around .029. These p r o p e r t i e s d e f i n e the pyroxene as being l i n e a r l y v a r i a b l e i n composition between D±S8 Hed]_2 = W050 E n ^ Fe£ and W 04/^1. En^o, E e ^ i . The pyroxene i s t h e r e f o r e d i o p s i d e . Quartz occurs i n equant, small g r a i n s with i r r e g u l a r , sharp boundaries. The m i n e r a l g e n e r a l l y shows uniform e x t i n c t i o n , but weak l a m e l l a r e x t i n c t i o n i s present i n a t l e a s t some g r a i n s i n every s e c t i o n . C a l c i t e occurs i n l a r g e , i r r e g u l a r , anhedra, i n t e r -s t i t i a l g r a i n s t h a t show e x c e l l e n t l a m e l l a r twinning. 24. A second type of amphibole with pleochroism t y p i c a l of hornblende, z c 16°, h i g h -ve 2V occurs i n f r e q u e n t l y i n some s e c t i o n s . The m i n e r a l i s c l o s e l y a s s o c i a t e d w i t h pyro-xene, which appears to have grown at the expense of the amph-i b o l e . A green, medium g r a i n e d , massive quartz d i o p s i d e skarn occurs l o c a l l y w i t h i n the quartz d i o p s i d e h o r n f e l s . Masses of skarn are conformable w i t h the surrounding r o c k s and c o n t a c t s are sharp. The composition of t h i s skarn i s s i m i l a r to t h a t of the green l a y e r s of quartz d i o p s i d e h o r n f e l s , but i t s g r a i n s i z e i s c o a r s e r than i n the h o r n f e l s . The skarn has a h o r n f e l s i c t e x t u r e . INTRUSIVE ROCKS B i o t i t e Quartz D i o r i t e P e t r o l o g y The stock e a s t of Haggart Creek f a u l t and the ' s i l l * west of i t are composed of b i o t i t e g r a n o d i o r i t e and o t h e r r e -l a t e d l i t h o l o g i c t y pes. The d i s t r i b u t i o n , l o c a t i o n and s i t e o f these bodies i s shown i n the accompanying g e o l o g i c map. The rocks v a r y i n composition and t h e i r c o l o u r index and the compo-s i t i o n of t h e i r p l a g i o c l a s e do not correspond w i t h those gener-a l l y found i n r e l a t i v e l y a c i d r o c k s . ab twin F i g u r e 16. P o r p h y r i t i c b i o t i t e q u a r t z i n o n z o n i t e p h e n o c r y s t s o f p l a g i o c l a s e , q u a r t z a n d b i o t i t e i n a g r o u n d m a s s  o f q u a r t z a n d f e l d s p a r . Some p l a g i o c l a s e p h e n o - c r y s t s a r e z o n e d . X - N i c o l s . x 15» 25. In g e n e r a l the g r a n i t i c rocks crop out w e l l . Most outcrops are deeply weathered and crumbly. J o i n t i n g i s gener-a l l y w e l l developed. The f r e s h rock i s l i g h t grey, but some phases are dark grey; f r e s h s u r f a c e s are darker c o l o u r e d than are weathered s u r f a c e s . The rock i s medium gr a i n e d ; g r a i n s of q u a r t z , p l a g i o c l a s e and b i o t i t e can be d i s t i n g u i s h e d i n handspecimens. The rocks west of Haggart Creek are g e n e r a l l y darker i n c o l o u r than those e a s t o f the f a u l t and they o f t e n c o n t a i n a l a r g e r p r o p o r t i o n of b i o t i t e and c h l o r i t e . ' Broadly speaking the g r a n i t i c rocks east of the f a u l t are more uniform i n composition and more a c i d i c than those west of i t and approach quartz monzonite and quartz d i o r i t e . West of the f a u l t the rocks g e n e r a l l y l a c k K - f e l d s p a r and are r i c h i n quartz and p l a g i o c l a s e : ; these rocks approach quartz gabbro to quartz d i o r i t e . E a s t of Haggart Creek f a u l t p l a g i o c l a s e i s c a l c i c andesine, w h i l e west of the f a u l t i t i s l a b r a b o r i t e . West of the f a u l t p l a g i o c l a s e tends to va r y r e g u l a r l y i n compo-s i t i o n . The f e l d s p a r i s more and more c a l c i c i n rocks o c c u r r i n g s u c c e s s i v e l y f u r t h e r west and ranges from A n ^ 2 "to A n ^ . The v a r i e t a l m i n e r a l i s b i o t i t e though some hornblende was noted. T h i n s e c t i o n s of the quartz d i o r i t e from east of the f a u l t show t h a t the rock v a r i e s from a p o r p h y r i t i c quartz mon-z o n i t e to a medium g r a i n e d g r a n o d i o r i t e . Estimated modes f o r these two types are presented below. Figure 17. Medium grained b i o t i t e g r a n o d i o r i t e . Shows both zoned and unzoned p l a g i o c l a s e grains  X - N i c o l s . x 15. 26. MINERALS Quartz P l a g i o c l a s e K - f e l d s p a r B i o t i t e Hornblende P o r p h y r i t i c B i o t i t e Quartz Monzonite 30$ 15$ 40$ 7$ Medium Grained b i o t i t e g r a n o d i o r i t e 30$ 30$ 20$ Minor c o n s t i t u e n t s of these rocks i n c l u d e z i r c o n , opaques, a p a t i t e , sphene, muscovite, z o i s i t e and s c h o r l i t e . Secondary m i n e r a l s are c a l c i t e , c h l o r i t e and s e r i c i t e which are p r e s e n t i n amounts up to 15$» The p o r p h y r i t i c rock i s made up of equant phenocrysts, which range i n s i z e up to 3 mm« a c r o s s and which c o n s t i t u t e up to a t h i r d of i t . G r a i ns i n the groundmass are commonly .1 mm. a c r o s s . Phenocrysts of quartz are equant, u n s t r a i n e d and have f a i r l y r e g u l a r boundaries. Quartz g r a i n s i n the groundmass have i r r e g u l a r boundaries. P l a g i o c l a s e phenocrysts are subhedral and t h i c k t a b u l a r . Most phenocrysts show o s c i l l a t o r y zoning and no d e f i n i t e t r a n d to e i t h e r normal or reverse z o n i n g c o u l d be e s t a b l i s h e d . Zoned p l a g i o c l a s e g r a i n s are more equant than are unzoned g r a i n s . Most zoned g r a i n s have s i x narrow outer zones around a l a r g e uniform c o r e . Zoned g r a i n s have smooth rounded boundaries, Figure 18. Partly altered porphyritic gabbroic b i o t i t e  quartz d i o r i t e from west of Haggart Creek.  X-Hicols. x 15. Figure 19. Par t l y altered gabbroic b i o t i t e quartz d i o r i t e  from west of Haggart Creek showing quartz pheno<  crysts with smooth resorbed boundaries surr- ounded by clay aggregates. X-I\ Ticols. x 1 5 . 27. whereas the boundaries of unzoned g r a i n s are g e n e r a l l y s t r a i g h t . Both the unzoned and zoned g r a i n s are of the same composition and average around An^Q. A s i d e from the u b i q u i t o u s a l b i t e twins, c a r l s b a d and p e r i c l i n e twins are f a i r l y common. The p l a g i o c l a s e i n the groundmass occurs i n anhedral g r a i n s about .1 mm. a c r o s s . Potash f e l d s p a r occurs as anhedral, i n t e r s t i t i a l g r a i n s i n the groundmass. Large g r a i n s show p e r t h i t i c i n t e r g r o w t h s of p l a g i o c l a s e along (001), while myrmekitic and granophyric i n t e r -growths of quartz and K - f e l d s p a r are common i n s m a l l e r g r a i n s . C a r l s b a d twinning i s common i n l a r g e r g r a i n s . B i o t i t e , the main v a r i e t a l m i n e r a l , occurs i n t h i n t a b u l a r euhedral g r a i n s up to 2 mm. a c r o s s . The m i n e r a l has the p l e o c h r o i c scheme:-X = e - pa l e y e l l o w green Y=Z = a = b - dark r e d brown Hornblende occurs i n roughly equant and sh o r t p r i s -matic g r a i n s w i t h ragged t e r m i n a t i o n s . The m i n e r a l i s p l e o c h r o i c i n greens and. shows s i e v e t e x t u r e . B i o t i t e i s c l o s e l y a s s o c i a t e d wi th i t . S e r i c i t i z a t i o n i s e v i d e n t i n the cor e s of some p l a g i o -c l a s e g r a i n s . Some b i o t i t e g r a i n s are completely r e p l a c e d by p e n n i n i t e , but i n most g r a i n s replacement i s only p a r t i a l and i s c o n t r o l l e d by the cleavage of b i o t i t e . E p i d o t e has formed as 28. an a l t e r a t i o n of hornblende. The medium g r a i n e d g r a n o d i o r i t e i s a t y p i c a l l y hyp-idiomorphie rock. G r a i n s i z e i s about 2 mm. P l a g i o c l a s e i n these r o c k s i s somewhat more c a l c i c than i t i s i n the p o r p h y r i t i c rocks and averages about A n ^ . The m i n e r a l occurs i n subhedral, t h i c k t a b u l a r g r a i n s about 2 mm. a c r o s s . About one t h i r d of p l a g i o c l a s e g r a i n s are zoned and i n these the zoning i s s i m i l a r to that d e s c r i b e d f o r the p o r p h y r i t i c rock. Twinning i n the p l a g i o c l a s e i s the same as that i n the p o r p h y r i t i c rock. Potash f e l d s p a r occurs i n anhedral and subhedral g r a i n s t h a t show c a r l s b a d twinning and which o f t e n c o n t a i n p e r t h i t i c l a m e l l a e . Quartz g r a i n s have i r r e g u l a r boundaries and wavy e x t i n c t i o n . B i o t i t e i s the v a r i e t a l m i n e r a l . Minor c o n s t i t u e n t s are more p l e n t i f u l and c o a r s e r g r a i n e d i n t h i s rock than they are i n the p o r p h y r i t i c v a r i e t y . A l t e r a t i o n by c h l o r i t e , s e r i c i t e and carbonate i s common and i s s i m i l a r to that d e s c r i b e d b e f o r e . At l e a s t two other phases e x i s t e a s t of Haggart Creek f a u l t . One, which appears r e s t r i c t e d t o the west end 29 of the s t o c k , i s a f i n e g r a i n e d , a p l i t i c type c o n t a i n i n g no mafic m i n e r a l s and made up e n t i r e l y of quartz and f e l d s p a r . The extent of t h i s phase i s not c e r t a i n . The con t a c t between t h i s phase and the normal types i s thought to be g r a d a t i o n a l . Another type which i s a p p a r e n t l y not r e s t r i c t e d i n l o c a l e i s a medium g r a i n e d , b i o t i t e r i c h phase i n which b i o t i t e makes up as much as one t h i r d of the rock. The c o n t a c t s are thought to be g r a d a t i o n a l and the extent o f the phase i s u n c e r t a i n . The g r a n i t i c rocks west of Haggart Creek f a u l t are a l t e r e d , a l l o t r i o m o r p h i c , g r e e n i s h to white, medium g r a i n e d a n d p p o r p h y r i t i c . T h e i r quartz and f e l d s p a r content i s v a r i a b l e . An average mode i s g i v e n below. P l a g i o c l a s e (Phenocrysts 15 - 25$ Quartz (Phenocrysts) 0 - 20$ K - f e l d s p a r (Phenocrysts) 0 - 2$ B i o t i t e (Phenocrysts) 10 - 20$ Quartz (Groundmass) 5 - 55$ K - f e l d s p a r (Groundmass) 0 - 20$ Hornblende occurs i n some specimens, but i s u s u a l l y e n t i r e l y absent. Minor c o n s t i t u e n t s i n c l u d e sphene, a p a t i t e , z i r c o n and i r o n s u l p h i d e s . S c h o r l i t e occurs uncommonly as a minor c o n s t i t u e n t . Secondary m i n e r a l s i n c l u d e c a l c i t e and c h l o r i t e . The amounts of these two m i n e r a l s v a r y c o n s i d e r a b l y . F i g u r e 2 0 . S t r o n g l y a l t e r e d g a b b r o i c b i o t i t e q u a r t z  d i o r i t e f r o m w e s t o f H a g g a r t C r e e k f a u l t  X - H i c o l s . x 1 5 . 3 0 One minor c o n s t i t u e n t which was not noted i n any t h i n s e c t i o n s i s a l l a n i t e . T h i s m i n e r a l occurs i n blac k , t h i n , i n d i -v i d u a l , p r i s m a t i c g r a i n s up to 2 cm. l o n g t h a t can be re c o g n i z e d i n handspecimens. T h i s m i n e r a l f i g u r e s prominently i n the p l a c e r sands of Haggart Creek and D u b l i n Gulch. The a l l a n i t e g i v e s a good X-ray powder p a t t e r n , and thus i s not metamict. P l a g i o c l a s e i n these rocks occurs as t h i c k , t a b u l a r , subhedral g r a i n s t h a t commonly have smooth, rounded boundaries and are about 2 mm. i n l o n g e s t dimension. I t s composition ranges from A n ^ to Ans£» Prom the few t h i n s e c t i o n s examined there i s a s u g g e s t i o n that p l a g i o c l a s e i s more and more c a l c i c i n rocks s u c c e s s i v e l y f u r t h e r west. P l a g i o c l a s e i s commonly zoned, but t h i s i s not u n i v e r s a l . The zoning i s o s c i l l a t o r y and s i m i l a r to that d e s c r i b e d p r e v i o u s l y . U s u a l l y a l a r g e core i s surrounded by from f i v e to nine narrow ou t e r zones. P l a g i o c l a s e shows a l b i t e , c a r l s b a d and p e r i c l i n e twinning. P l a g i o c l a s e i s p a r t i a l l y a l t e r e d to s e r i c i t e and c a l c i t e and t h i s a l t e r a t i o n i s g e n e r a l l y so complete that o n l y o u t l i n e s of p l a g i o c l a s e g r a i n s are e v i d e n t and even twin l a m e l l a e are obscured. Potash f e l d s p a r ( p r o b a b l y o r t h o c l a s e ) i s i n l a r g e , anhedral g r a i n s of dimensions s i m i l a r to those of p l a g i o c l a s e and shows c a r l s b a d twinning. Quartz occurs i n equant, rounded g r a i n s 2 - 3 mm. across u s u a l l y w i t h smooth 'resorbed' boundaries, around which v e r y f i n e 31 g r a i n e d aggregates of c l a y m i n e r a l s are randomly arranged. The m i n e r a l has uniform e x t i n c t i o n and sometimes shows c o n c e n t r i c zones of t i n y equant i n c l u s i o n s . B i o t i t e occurs as t h i c k , t a b u l a r g r a i n s which gen-e r a l l y have ragged t e r m i n a t i o n s . The m i n e r a l shows p a r t i a l or complete pseudomorphous replacement by c h l o r i t e . The groundmass of these rocks i s g e n e r a l l y a l t e r e d to a f i n e g r a i n e d aggregate o f c l a y m i n e r a l s , but where i t i s r e l a t i v e l y f r e s h i t c o n s i s t s of mixtures of quartz, K - f e l d s p a r and c l a y s . G r a i n s i z e i s g e n e r a l l y l e s s than . 0 5 mm. From the f o r e g o i n g d e s c r i p t i o n i t i s c l e a r t h a t the rock i s n e i t h e r a quartz d i o r i t e nor a quartz gabbro. P l a g i o -c l a s e i s c e r t a i n l y t y p i c a l of gabbros, but the l a c k of normal mafic c o n s t i t u e n t s f o r gabbros ( i . e . pyroxenes) and the presence of b i o t i t e and some hornblende i s more t y p i c a l of d i o r i t i c r o c k s . The c o l o u r index i s too h i g h f o r a d i o r i t i c rock. These con-f l i c t i n g f e a t u r e s make i t n e c e s s a r y to g i v e the rock a h y b r i d name l i k e gabbroic or c a l c i c b i o t i t e quartz d i o r i t e or even d i o r i t i c quartz b e a r i n g b i o t i t e gabbro. The f i r s t of these two names i s p r e f e r r e d . Figure 2 1 . Windlass above o l d s h a f t sunk on the northern contact of the g r a n o d i o r i t e stock  of D u b l i n Gulch (here m i n e r a l i z e d by a u r i - ferous a r s e n o p y r i t e ) . Note the d i s t i n c t  f o l i a t i o n i n the g r a n o d i o r i t e outcrop, which  i s thought to be due to shearing upon i n - t r u s i o n along the f a u l t at the contact  with the metamorphic rocks. 3 2 S t r u c t u r e Stratum contours on the upper s u r f a c e of the stock give a c l e a r i d e a of the form of the g r a n o d i o r i t e stock. F i g u r e shows the makeup of the stock i n r e l a t i o n to the top-ography. The stratum contours are a l s o shown. The stock'has two main, somewhat di v e r g e n t , ' r i d g e s ' . The v a l l e y between these r i d g e s c o i n c i d e s w i t h D u b l i n Gulch. Areas where the topographic s u r f a c e i s h i g h , are u n d e r l a i n by highs i n the upper s u r f a c e of the stock. The dip of the n o r t h and south c o n t a c t s of the stock i s f a i r l y uniform and averages about twenty-five degrees. To the west, the stock g r a d u a l l y t h i n s and becomes dyke l i k e . West of Haggart Creek f a u l t the i n t r u s i o n i s more s i l l - l i k e . On the northwest s i d e of the stock, f o l i a t i o n s i n the metamorphic rocks conform wi t h the northwestward dip of the g r a n i t i c c o n t a c t , w h i l e on the southeast s i d e f o l i a t i o n s are not conformable with the contact.. The northwest margin of the stock i s c o n s i d e r e d to be a f a u l t c o n t a c t w i t h the country rocks. The f a u l t i s l o c a l l y w e l l exposed and conforms wi t h the f o l i a t i o n of the metamorphic rocks. O c c a s i o n a l l y d i s t i n c t l a y e r i n g i n the g r a n i t i c rocks, due to s h e a r i n g i n them, occurs p a r a l l e l to and near the f a u l t . Close to and west of Haggart Creek f a u l t , f o l i a t i o n s 33 south of the g r a n i t i c rocks are t r a n s v e r s e to the o r i e n t a t i o n of the stock, but f u r t h e r west, they become more conformable. Prom the stratum contours i t i s apparent t h a t the quartz d i o r i t e stock forms the backbone of Potato H i l l s and that the topography west of Potato H i l l s i s s i m i l a r i n shape to t h a t of the stock. S e v e r a l l e n t i c u l a r s i l l - l i k e masses of quartz d i o r i t e around the margins of the stock appear to be apophyses or o f f -shoots from the main mass. O r i g i n and mode of emplacement The g r a n i t i c rocks i n t h i s area e x h i b i t f e a t u r e s char-a c t e r i s t i c of both epi-and mesozonal types (Buddington 1959) . E p i z o n a l f e a t u r e s of the stock i n c l u d e the homophanous t e x t u r e of the stock, composite s t r u c t u r e due to the presence of v a r i o u s phases, granophyric t e x t u r e , the tourmaline a u r e o l e , the l a c k of i n c l u s i o n s of c o u n t r y rock i n the stock and, p o s s i b l y , the f a u l t c o n t a c t a l o n g p a r t of the margin of the stock. Mesozonal f e a t u r e s are the quartz d i o r i t i c composition, the hypidiomorphic t e x t u r e and l a c k of m i a r i o l i t i c c a v i t i e s , the l a c k of c h i l l e d margins, the low grade r e g i o n a l metamorphic nature of country rocks and the presence of p e r i p h e r a l h o r n f e l s e s . I t seems l i k e l y t h a t the g r a n i t i c rocks were emplaced by s t o p i n g and i n t r u s i o n t h a t was i n i t i a l l y c o n t r o l l e d by a bedding f a u l t . I t i s c o n s i d e r e d that the presence of two types F i g u r e 22» Stratum contours on the upper s u r f a c e of  g r a n o d i o r i t e stock e a s t of Haggart Creek  with 3 accompanying c r o s s s e c t i o n s . STRATUM CONTOURS ON THE UPPER SURFACE OF GRANODIORITE STOCK EAST OF HAGGART CREEK WITH THREE ACCOMPANYING CROSS-SECTIONS 34. of p l a g i o c l a s e i n the rock comprising the stock may be used as a c l u e to and i n support of the e s s e n t i a l l y magmatic o r i g i n of the sto c k . The zoned f e l d s p a r i s c o n s i d e r e d to have formed before the unzoned f e l d s p a r and r e f l e c t s the changes i n pre-ssure and temperature c o n d i t i o n s that p r e v a i l e d d u r i n g the p e r i o d of movement of the magma from i t s b i r t h p l a c e to i t s new home i n the zoning. Unzoned f e l d s p a r i s thought to have c r y -s t a l l i z e d when c o o l i n g of the s t i l l p a r t i a l l y l i q u i d magma occu r r e d a f t e r the movement of emplacement ceased. The p r o p o r t i o n s o f the two types o f p l a g i o c l a s e g i v e a rough i d e a of the r e l a t i v e amounts of l i q u i d and s o l i d during the emplacement stage. At the time of emplacement the c r y s t a l mush was approximately 25$ s o l i d . The s i m i l a r i t y of zoned c r y s t a l s i n the stock to those i n the s i l l west of Haggart Creek f a u l t i s thought to be evidence of t h e i r common o r i g i n . The p r o g r e s s i v e change of p l a g i o c l a s e compositions along the l e n g t h of the s i l l west of Haggart Creek f a u l t suggests t h a t the motion of magma d u r i n g emplacement was from west to east i n accordance with the p l a g i o c l a s e phase diagram. Quartz F e l d s p a r Porphyry S e v e r a l dykes o f . q u a r t z f e l d s p a r porphyry crop out i n the area. T h e i r l o c a t i o n and d i s t r i b u t i o n i s shown on the acc-3 5 . ompanying g e o l o g i c map. The dykes are made up of a w h i t i s h f i n e , g r a i n e d groundmass i n which equant phenocrysts of quartz and occas-i o n a l l y f e l d s p a r are randomly d i s t r i b u t e d . The rock i s s t r o n g l y a l t e r e d , i t s o r i g i n a l c o n s t i t u e n t s , except q u a r t z , have a l l been completely converted to micas, so t h a t the rock i s i n d i s t i n g u i s h a b l e from the a l t e r e d b a s i c quartz d i o r i t e i n t h i n s e c t i o n s . P o r p h y r i t i c amygdaloidal b a s a l t F l o a t of p o r p h y r i t i c b a s a l t occurs at two l o c a l i t i e s west of Haggart Creek f a u l t . (See accompanying map) I t i s thought t h a t the f l o a t o v e r l i e s a v o l c a n i c f e e d e r dyke or neck, s i n c e the area over which i t i s d i s t r i b u t e d i s s m a l l . Por-p h y r i t i c b a s a l t occurs a t other l o c a l i t i e s i n the v i c i n i t y of the map area. Prom r e g i o n a l mapping (Green 1962) p o r p h y r i t i c b a s a l t i s c o n s i d e r e d to be of T e r t i a r y age. The f l o a t i s dark grey or bl a c k i n c o l o u r , weathers r u s t y brown and i s massive. I t i s made up of a f i n e g r a i n e d e q u i g r a n u l a r groundmass of bytownite, a u g i t e and b i o t i t e i n which phenocrysts ( 3 mm.) of p l a g i o c l a s e , pyroxene and quartz are randomly d i s t r i b u t e d . The average estimated mode found i n t h i n s e c t i o n s of specimens from both l o c a l i t i e s i s g i v e n below. Figure 23. Porphyritic amygdaloidal basalt. Phenocryst of bytownite with smooth boundary and reaction  rim i n a groundmass of randomly oriented thin  tabular plagioclase grains. The round grain,  lower l e f t , i s an amygdule of c a l c i t e .  X-Nicols, x 15. Figure 24. Large phenocrysts made up of ind i v i d u a l rounded  grains of sanidine and cut by 'worms' of plag- ioclase and quartz i n porphyritic amygdaloidal basalt. X-Mcols. x 15. 36. A u g i t e (Groundmass) 20$ A u g i t e (Phenocrysts) 5$ Bytownite (Phenocrysts) 10$ Bytownite (Groundmass 30$ Quartz 5$ B i o t i t e 10$ C a l c i t e 10$ S a n i d i n e , o l i v i n e , sphene and p y r i t e are c o n s t i t u e n t s found i n one t h i n s e c t i o n i n d e c r e a s i n g order of abundance. The groundmass c o n t a i n s randomly o r i e n t e d , t h i n t a b u l a r , euhedral g r a i n s of p l a g i o c l a s e (Anyo) that show a l b i t e twinning. A u g i t e (W039 Fe£) occurs as anhedral, equant, i n t e r s t i t i a l g r a i n s i n the groundmass. The m i n e r a l has a 27 of 50° and i s b i a x i a l + ve, i t s b i r e f r i n g e n c e i s .026 and n y = 1.675. B i o t i t e occurs as t i n y i n t e r s t i t i a l f l a k e s i n the groundmass. The m i n e r a l i s p l e o c h r o i c i n browns. Z:oned phenocrysts of bytownite are anhedral, equant and more than 3 mm. acro s s . ' They have resorbed, smoothly rounded boundaries and show c a r l s b a d and a l b i t e twinning. T h e i r composition i s c l o s e to the groundmass p l a g i o c l a s e . A u g i t e phenocrysts occur as subhedral, roughly equant g r a i n s t h a t show a narrow ou t e r zone surrounding a l a r g e r i n n e r F i g u r e 2 5. G r a i n o f L i o p s i t i c A u g i t e i n A u g i t i t e s h o w i n g  c l e a v a g e ( 1 1 0 ) a n d p a r t i n g ( 1 0 0 ) a s w e l l a s  t w i n n i n g o n ( 1 0 0 ) .  X - N i c o l s . x 4 5 ~ F i g u r e 26 . L a r g e g r a i n s o f h o r n b l e n d e r i m m e d b y s m a l l  g r a i n s o f a c t i n o l i t e ( a c i c u l a r h a b i t ) m' A u g i t i t e . O t h e r m i n e r a l s a r e b i o t i t e ~  a l b i t e a n d p y r o x e n e . 1 N i c o l . x 4 5 . 3 7 . core. The outer zone has a lower r e f r a c t i v e index than the core. Quartz occurs as u n s t r a i n e d , equant phenocrysts with smooth resorbed boundaries. A l a r g e (1 cm.) equant phenocryst of s a n i d i n e made up of a number of i n d i v i d u a l , d i f f e r e n t l y o r i e n t e d g r a i n s of that m i n e r a l and cut by t i n y wormlike v e i n l e t s of p l a g i o c l a s e or quartz, that t r a n s g r e s s g r a i n boundaries, occurs i n one t h i n s e c t i o n . Anhedral phenocrysts of o l i v i n e a l s o occur i n t h i s s e c t i o n . The m i n e r a l i s a l t e r e d to s e r p e n t i n e along f r a c t u r e s . Rounded knots of y e l l o w i s h p r i s m a t i c r a d i a l l y arranged c a l c i t e c r y s t a l s occur i n the b a s a l t . I t i s considered t h a t t h i s m i n e r a l i s a v e s i c l e f i l l i n g . The c a l c i t e knots or amyg-dules are up to 5 nun. a c r o s s . A l t e r a t i o n of t h i s rock type i s weak. A u g i t i t e Two s m a l l , d y k e - l i k e masses of dark green, f i n e to c o a r s e - g r a i n e d a u g i t i t e occur west of Haggart Creek f a u l t . Out-crops are covered w i t h dark green r e s i d u a l s o i l . C ontacts with country rocks are nowhere exposed, but the masses trend across the f o l i a t i o n o f the micaceous q u a r t z i t e s t h a t surround them. The a u g i t i t e i t s e l f i s u n f o l i a t e d and l a c k s l a y e r i n g . 38 The rock i s made up of an aggregate of euhedral to subhedral equant c r y s t a l s of pyroxene and s h o r t p r i s m a t i c g r a i n s of amphibole i n v a r y i n g p r o p o r t i o n s . B i o t i t e i n v a r y -i n g amounts i s i n c l u d e d i n pyroxene and occurs i n t e r s t i t i a l to i t . A l b i t e occurs i n t e r s t i t i a l l y . G r a i n s i z e ranges between .2 mm. and 5 mm., but i s uniform i n i n d i v i d u a l specimens. Modes are q u i t e v a r i a b l e f o r even specimens from w i t h i n a few f e e t o f each other have w i d e l y d i f f e r e n t miner-a l o g i c a l c o n s t i t u t i o n . Two extremes are presented below. D i o p s i d e a u g i t e 50 - 7$ Hornblende 5 - 51$ B i o t i t e 5 - 20$ A l b i t e 15 - 10$ K - f e l d s p a r 15 - 0$ O l i v i n e 0 - 1 $ Ep i d o t e 2$ Minor c o n s t i t u e n t s i n c l u d e , i n d e c r e a s i n g order of abundance, a p a t i t e , sphene and magnetite. Secondary m i n e r a l s are c a l c i t e , c h l o r i t e and a c t i n o l i t e . C l inopyroxene occurs as subhedral g r a i n s g e n e r a l l y surrounded by amphibole and o f t e n showing p o i k i l i t i c t e x t u r e due to i n c l u d e d b i o t i t e . The m i n e r a l has a 2V of 5 2 ° , i s b i a x i a l +ve and i s p l e o c h r o i c i n very weak bluegreen and pink; the scheme was not determined. Twinning on (100) i s common. The m i n e r a l has a b i r e f r i n g e n c e of .027 and a r e f r a c t i v e index Figure 27. "Checkerboard" twinning i n i n t e r s t i t i a l a l b i t e  from a u g i t i t e . x 45. n y = 1.675. The composition i s near WO^Q E n ^ Fe^ ( d i o p s i d e a u g i t e ) . Two amphiboles occur. The commonest type i s coarse g r a i n e d , c r y s t a l s are subhedral and bent. I t i s b i a x i a l -ve with 2V=75°, shows twinning on (100) and i s p l e o c h r o i c as f o l l o w s : X a - pa l e green Y b - ve r y l i g h t green Z c - moderate blue green. These p r o p e r t i e s are c h a r a c t e r i s t i c of common hornblende. The coarse g r a i n e d amphibole i n c l u d e s r e l i c t c e n t r e s of pyroxene. A f i n e g r a i n e d amphibole occurs as a c i c u l a r needles t h a t pro-j e c t out of the c o a r s e r amphibole and l e n d i t a ragged appear-ance. T h i s amphibole i s c o n s i d e r e d to be a c t i n o l i t i c i n comp-o s i t i o n . B i o t i t e i s p l e o c h r o i c as f o l l o w s : c - l i g h t green a=b - kh a k i green The m i n e r a l occurs as equant bent f l a k e s i n pyroxene and i s i n t e r s t i t i a l to hornblende. The common f e l d s p a r i s a l b i t i c . I t occurs i n t e r s t i -t i a l l y as anhedral g r a i n s that show 'chekerboard 1 twinning. The composition ..was found to be A n 2 from 2VZ=78-J-0. K - f e l d s p a r occurs i n some specimens, i t i s l e s s common than a l b i t e . Figure 28. Phase I minor f o l d s i n micaceous q u a r t z i t e  which plunge eastward at 20° . On ridge north of 15 Pup The o r i g i n of t h i s r o c k i s u n c e r t a i n . S i m i l a r rocks are not r e p o r t e d from the v i c i n i t y and i t i s assumed t h a t the rock i s e i t h e r a b a s i c phase of the gabbroic quartz d i o r i t e or a phase of s y e n i t i c a c t i v i t y r e l a t e d to the quartz d i o r i t e . A l t e r n a t e l y t h i s rock may be a 'made ove r 1 b a s a l t . M i n e r a l -ogic f e a t u r e s are c o n f l i c t i n g , but i t seems l i k e l i e s t t h a t a u g i t i t e i s a m e t a s o m a t i c a l l y a l t e r e d gabbroic phase r e l a t e d to quartz d i o r i t e . STRUCTURAL GEOLOGY GENERAL STATEMENT The s t r u c t u r a l geology i s complex. The l a c k of l i t h o l o g i c markers and s c a r d i t y of outcrop make i t d i f f i c u l t to determine the major s t r u c t u r a l elements. A study of minor s t r u c t u r e s has helpe d to c l a r i f y the s t r u c t u r a l h i s t o r y . The b a s i c s t r u c t u r a l p a t t e r n has been d e s c r i b e d i n terms of the l i t h o l o g i c d i v i s i o n s s et out p r e v i o u s l y . Two phases of f o l d i n g can be r e c o g n i z e d i n the area. The f i r s t of these (Phase I) was a strong phase, which has produced s u b i s o c l i n a l f o l d s with east t r e n d i n g axes. A l a t e r and separate f o l d i n g phase ( P h a s e l l ) has produced open warps or w r i n k l e s on northwest t r e n d i n g axes t h a t have a f f e c t e d the o r i e n t a t i o n of f o l i a t i o n only l o c a l l y . Two important east 41. t r e n d i n g f a u l t s are r e c o g n i z e d and these are cut by l a t e r n o r t h t r e n d i n g f a u l t s which have had c o n s i d e r a b l e d i p s l i p movement on them and which have a f f e c t e d the o r i e n t a t i o n of minor s t r u c t u r e s . In the f o l l o w i n g pages minor s t r u c t u r e s are f i r s t des-c r i b e d and c o n c l u s i o n s are drawn from them. Major s t r u c t u r a l f e a t u r e s are then d e s c r i b e d and a t e c t o n i c h i s t o r y i s presented. MINOR STRUCTURES F o l i a t i o n Most of the rocks e x h i b i t a w e l l developed p l a n a r s t r u c t u r e which has been mapped as f o l i a t i o n . F o l i a t i o n i s thought to be l a r g e l y mimetic a f t e r o r i g i n a l bedding and marked by c r y s t a l growth, p a r t i c u l a r l y of mica along these p l a n e s . In o n l y a few p l a c e s c o u l d the r e l a t i o n s h i p between bedding and f o l i a t i o n be a s c e r t a i n e d , but i n a l l such cases the two were p a r a l l e l or n e a r l y so. G l e i t b r e t t s t r u c t u r e d e s c r i b e d by McTaggart ( i 9 6 0 ) i n the Keno H i l l a rea to the south occurs spar-i n g l y . The a t t i t u d e of f o l i a t i o n i s by no means uniform over the e n t i r e area, but i n a g e n e r a l way dips are moderate to the n o r t h e a s t i n t h a t p a r t of the map area west of Haggart Creek f a u l t , while they are moderate and to the west and northwest east of t h i s f a u l t . The accompanying t r e n d map i l l u s t r a t e s t h i s . F i g u r e 29* Contoured stereogram,of poles to f o l i a t i o n e a s t of Haggart Creek f a u l t . The poles f a l l  a long a gr e a t c i r c l e whose pole c o i n c i d e s  w i t h the Phase I l i n e a t i o n i n the area east  of Haggart Creek f a u l t . Note the weak ten- dency toward l a t e r a l spreading of the pole s  along a second g r e a t c i r c l e whose pole  c o i n c i d e s with Phase I I l i n e a t i o n s .  Lower Hemisphere, equal area Schmid p r o j e c t i o n . POLES TC FOLIATION EAST OF HAGGART CREEK FAULT F i g u r e 30. Contoured stereogram of pole s to f o l i a t i o n i n micaceous q u a r t z i t e s west of Haggart Creek  f a u l t . The poles f a l l along a gr e a t c i r c l e  which i s somewhere between the two l i m i t i n g  c i r c l e s shown on the diagram. Lower Hemisphere, equal area Schmid p r o j e c t i o n . POLES TO FOLIATION WEST OF HAGGART CREEK F-VULT 243 p l o t t e d 1 1 0 - -5V. | 1 -5 - 1 -5V. | I L 5 - 5 •/ . ~ ] 5 - 10 V . F i g u r e 31» Contoured stereogram of poles to f o l i a t i o n  i n the number One v e i n c r o s s c u t . Note the  s i m i l a r i t y to f i g u r e 3 Q» Lower Hemisphere, equal area Schmid p r o j e c t i o n . P O L E S TO F O L I A T I O N N U M B E R O N E C R O S S C U T 1 1 0 - 2 42 St e r e o g r a p h i c p l o t s of pole s to f o l i a t i o n were made f o r each of the s t r u c t u r a l u n i t s w i t h i n the map area. F o r the area east of Haggart Creek f a u l t such p o l e s p l o t i n an e l l i p t i -c a l area, which f a l l s along a g r e a t c i r c l e whose pole plunges toward 265° a t 1 8 ° . A weak tendency to l a t e r a l s preading of the p o l e s along a g r e a t c i r c l e whose pole plunges toward 353° a t 28 can he n o t i c e d . (See f i g u r e 29) In the ar e a west of Haggart Creek f a u l t u n d e r l a i n by micaceous q u a r t z i t e s , p o l e s to f o l i a t i o n p l o t along a g r e a t c i r c l e whose pole plunges 78 /20 . (See f i g u r e 30) A separate p l o t of p o l e s to f o l i a t i o n measured in-the c r o s s c u t on number One V e i n was a l s o made. . T h i s p l o t conforms w e l l w i t h t h a t of p o l e s to f o l i a t i o n i n micaceous q u a r t z i t e s west of Haggart Creek f a u l t w i t h i n which the number One c r o s s c u t l i e s . (See f i g u r e 31) A p l o t o f pole s to f o l i a t i o n i n the no r t h e r n q u a r t z i t e s west of Haggart Creek f a u l t , although based on r e l a t i v e l y few re a d i n g s , shows t h a t p o l e s l i e along a gr e a t c i r c l e whose pole trends 1 0 0 / 0 . (See f i g u r e . 32) Poles to f o l i a t i o n were a l s o p l o t t e d f o r the southern grey q u a r t z i t e s west of Haggart Creek f a u l t . The p o l e s p l o t i n an e l l i p t i c a l a r e a t h a t f a l l s a long a gr e a t c i r c l e whose pole plunges toward 79° a t 28 ° . (See f i g u r e 33) F i g u r e 32. Contoured stereogram of Phase I l i n e a t i o n  and p o l e s to f o l i a t i o n i n q u a r t z i t e s n o r t h  of B l a ck P h y l l i t e f a u l t and west of Haggart  Creek f a u l t . Lower Hemisphere equal area Schmid p r o j e c t i o n . POLES TO FOLIATION t PHASE I LINEATON WEST OF HAGGART CREEK FAULT NORTH OF QLACK PHYLLITE FAULT 5 0 poles to f o l i a t i o n p l o t t e d 6 0 l ineat ions plot ted F i g u r e 3 3« Contoured stereogram of Phase I l i n e a t i o n and  pole s to f o l i a t i o n i n massoic q u a r t z i t e s west  of Haggart Creek f a u l t and south of Rex f a u l t ,  lower Hemisphere, equal area Schmid P r o j e c t i o n . 50 each pi otte d POLES TO FOLIATION PHASE I LINEATION SOUT H OF REX FAULT foliation I 1 0 - 10% 1 0 - 2 0 « fa > 2 0 •/„ lineation | | 0 - 10 1 0 - 5 0 ' / . > 5 0°/c F i g u r e 3k. Contoured stereogram of l i n e a t i o n s of Phase I  i n micaceous q u a r t z i t e s west of Haggart Creek  f a u l t . Lower Hemisphere equal area Schmid p r o j e c t i o n . PHASE I LINEATION WES T OF HAGGART C R E E K FAULT F i g u r e 3 5. Contoured stereogram of l i n e a t i o n s of Phase I  east of Haggart Creek f a u l t . Lower Hemisphere, equal area Schmid p r o j e c t i o n . P H A S E I Ll NEATTON E A S T OF H A G G A R T C R E E K FAULT F i g u r e 36» Contoured stereogram of l i n e a t i o n s of Phase I I  west of Haggart Creek f a u l t . lower hemisphere, equal area Schmid p r o j e c t i o n . PHASE E LINEATION WEST OF HAGGART CREEK FAULT | | 0 - 2 ° . o 1 1 2 - 10V. + 43 L i n e a t i o n L i n e a t i o n i s f a i r l y w e l l developed i n most rocks t h a t crop out i n the area. Two d i f f e r e n t types of l i n e a r s t r u c t u r e s occur. The commonest of them (Phase I ) , takes the form of s t r i a t i o n s and minute w r i n k l e s which are most prominent west of Haggart Creek f a u l t and l e s s so e a s t of i t . P l o t s of t h i s l i n e a t i o n (Phase I) were made f o r each of the subareas f o r which p l o t s of f o l i a t i o n were made. Por the a r e a east of Haggart Creek f a u l t , the p l o t (which i s based on only $0 readings and t h e r e f o r e not accurate) shows a c o n c e n t r a t i o n a t 272 /15 , (see f i g u r e 35) > which c o i n c i d e s roughly w i t h the pole to the g r e a t c i r c l e on which f o l i a t i o n p o l e s f o r t h i s area p l o t ( 2 6 5 / l 8)(see f i g u r e 29 ) . I t should be noted here t h a t the plunge of l i n e a t i o n s becomes p r o g r e s s -i v e l y s m a l l e r f u r t h e r to the e a s t and on Potato H i l l s t h i s l i n e a t i o n i s h o r i z o n t a l . L i n e a t i o n i s not as w e l l developed e a s t of Haggart Creek f a u l t as i t i s west of the f a u l t . The same type of p l o t of Phase I l i n e a t i o n west of Haggart Creek f a u l t shows a w e l l d e f i n e d c o n c e n t r a t i o n a t 86 /12 . (See f i g u r e 34) A f a i r c o i n c i d e n c e of t h i s c o n c e n t r a t i o n w i t h the pole to the great c i r c l e of f o l i a t i o n s (isee f i g u r e 30) at 80/20 i s e v i d e n t . Por the n o r t h e r n q u a r t z i t e s west of Haggart Creek f a u l t a c o n c e n t r a t i o n of l i n e a t i o n s based on scanty data f a l l s 4 4 a t 9 2 / 0 . (Compare w i t h 100/0 f o r the pole to the g r e a t c i r c l e through f o l i a t i o n p o l e s here.) (See f i g u r e 32) Phase I l i n e a t i o n s i n the southern q u a r t z i t e s west Haggart Creek f a u l t a l s o based on scanty data concentrate around 7 2 / 3 2 , which a g a i n c o i n c i d e s f a i r l y w e l l w i t h the pole to the g r e a t c i r c l e on which p o l e s to f o l i a t i o n f o r t h a t area f a l l v i z . 7 9 / 2 8 . (See f i g u r e 33) The second type of l i n e a t i o n (Phase I I ) i s a w r i n k l e l i n e a t i o n found o n l y i n the more micaceous members of the sequence. The w r i n k l e s of t h i s l i n e a t i o n are l a r g e r and more open than those of the p r e v i o u s l y d e s c r i b e d l i n e a t i o n . Wherever the two l i n e a t i o n s are seen t o g e t h e r t h i s open w r i n k l e l i n e a t i o n i s l a t e r than the s t r i a t i o n s of the f i r s t l i n e a t i o n . The s t e r -eographic p l o t of t h i s second l i n e a t i o n f o r the area west of Haggart Creek f a u l t shows a c o n c e n t r a t i o n a t 3 2 8 / 2 4 . (See f i g -ure 36) Although the second l i n e a t i o n was observed elsewhere i n the a r e a i t i s not common enough or w e l l developed enough to a l l o w a s t a t i s t i c a n a l y s i s . In g e n e r a l the second l i n e a t i o n m a i n t a i n s i t s o r i e n t a t i o n u n i f o r m l y throughout the area. Minor Polds Minor f o l d s i n the a r e a are of f o u r types and each type i s r e s t r i c t e d to a p a r t i c u l a r p a r t of the map area. Minor f o l d s (Phase I) are commonest i n micaceous q u a r t z i t e west of Haggart Creek f a u l t . Two types of f o l d s with 4 5 . parallel plunges separate this region into three parts. The three parts are subparallel, east-west trending bands, whose boundaries are not defined well enough to be mapped. In the northern and southern bands which are both wider than the central band, minor folds have north up and over south sense. In the narrow central band minor folds are much less abundant than they are in the marginal bands and where their sense i s evident i t is opposite (i.e. south up). Although the minor folds are of opposite senses their style is identical. (See figures 58, 39> 40) Both fold types are cylindoidal and similar. The attitude of their axes is con-stant, but the axial planes of minor folds show considerable variation in dip and strike. The poles of attitudes of those few axial planes that were measured f a l l near the great circle containing poles to fo l i a t i o n . Limbs of folds also show varia-tions in attitudes; this i s reflected in the fact that there is only one zone of concentration on the plot of poles to f o l i a -tion. The average angle between limbs of minor folds varies from 90° to 30°, but averages about 45°• Thickening at the hinge with thinning on the limbs has occurred and the thinning ratio i s about ls.2 for most minor folds. A l l fold hinges are well rounded. Axial plane cleavage is very poorly developed in most minor folds. Recrystallization along the axial planes of minor folds has occurred and is particularly prominent in mica rich rocks. Lineation parallel to fold axes occurs F i g u r e 37. Phase I minor f o l d s i n grey p h y l l i t e n o r t h of McGann Creek. F i g u r e s 38, 39, 40. C r o s s - s e c t i o n s of minor f o l d s of ffiase 1 from v a r i o u s p a r t s of the map area.  The c r o s s - s e c t i o n s are p e r p e n d i c u l a r to the  plunge of the f o l d s and are o r i e n t e d so  that n o r t h i s on the l e f t and s o u t h on the  r i g h t . S t i p p l e s i n d i c a t e q u a r t z i t e . Black i n d i c a t e s massive white q u a r t z . Dashes i n d i c a t e grey p h y l l i t e . PHASE I MINOR FOLDS 5 fee t 10 feet PHASE I MINOR FOLDS 6 j n -6 in -3 i n 7 in 2 feet — 1 foot F i g u r e 41. Contoured stereogram of Phase I f o l d axes west of Haggart Creek f a u l t . Note p a r a l l e l - ism to f i g u r e 34. Lower hemisphere,equal area,Schmid p r o j e c t i o n . P H A S E I F O L D A X E S WEST OF H A G G A R T C R E E K FAULT ( in number one vein c r o s s c u t ) 46. on the limbs of the minor f o l d s , but i t i s g e n e r a l l y l a c k i n g on the h i n g e s . A s t e r e o g r a p h i c p l o t of f o l d axes from the number One c r o s s c u t shows a c o n c e n t r a t i o n a t 83/22. (See f i g u r e 41) I t should be noted that t h i s c o n c e n t r a t i o n i s c l o s e to the concen-t r a t i o n of Phase I l i n e a t i o n (86/12) and to the pole of the g r e a t c i r c l e on which po l e s to f o l i a t i o n f o r the micaceous q u a r t z i t e west of Haggart Creek f a u l t c o ncentrate (80/20). A t h i r d type of minor f o l d (Phase I I ) can be r e c o g -n i z e d i n the area west of Haggart Creek f a u l t . Minor f o l d s of t h i s type are uncommon, but enough of them are present to a l l o w a d e s c r i p t i o n : t h e i r sense i s south-west up with r e s p e c t to n o r t h - e a s t . The f o l d s are open and c y l i n d r o i d a l and t h e i r f o l d hinges a r e - w e l l rounded. T h e i r a x i a l ^planes dip g e n e r a l l y to the west at angles between 40° and 6 0 ° and s t r i k e about 170°. The a t t i t u d e s of the limbs are f a i r l y c o n s t a n t i n those f o l d s observed and the angle between limbs i s a l s o f a i r l y c o n s t a n t at about 100°. No t h i c k e n i n g and t h i n n i n g has o c c u r r e d . T h i s t h i r d type of f o l d plunges to the northwest a t moderate angles and although too few of them were observed f o r s t e r e o g r a p h i c a n a l y s i s they appear to be p a r a l l e l to the second l i n e a t i o n d e s c r i b e d above. Minor f o l d s of Phase I west of Haggart Creek f a u l t are d i f f e r e n t from those of t h a t phase east of the f a u l t . Two f e a t u r e s d i s t i n g u i s h them. The f i r s t i s t h e i r o r i e n t a t i o n . F i g u r e 42. Contoured stereogram of pol e s to .joints i n  metamorphic rocks west of Haggart Creek  f a u l t . Note p a r a l l e l i s m to f i g u r e 3 4 & 4 1 . Lower Hemisphere equal area Schmid p r o j e c t i o n . P O L E S TO J O I N T S M E T A M O R P H I C R O C K S WEST OF HAGGART C R E E K FAULT | | 0 - fl. Figure 43. Contoured stereogram of poles to .joints i n metamorphic rocks east of Haggart Creek f a u l t .  Note t h a t the dominant j o i n t set co i n c i d e s w i t h  Phase I I l i n e a t i o n (see f i g u r e 36JT  Lower Hemisphere equal area Schmid p r o j e c t i o n . POLES TO JOINTS METAMORPHIC ROCKS EAST OF HAGGART CREEK FAULT 47. East of the f a u l t minor f o l d s plunge to the west at shallow angles i n c o n t r a s t to the eastward plunge of f o l d s west of i t . Too few o b s e r v a t i o n s of these minor f o l d s were made to a l l o w a s t e r e o g r a p h i c a n a l y s i s of a x i a l t rend i n both areas; however, t h e i r axes are p a r a l l e l to the Phase I l i n e a t i o n . ' The second d i f f e r e n c e i s i n the angle between the limbs of minor f o l d s . T h i s angle v a r i e s from 50° to 15° and averages about 3 0 ° , i n minor f o l d s e a s t of Haggart Creek f a u l t . E a s t of the f a u l t minor f o l d s are more i s o c l i n a l than those west of i t . The a t t -i t u d e s of the a x i a l plane and f o l d limbs are somewhat l e s s v a r -i a b l e f o r f o l d s e a s t of the f a u l t than they are f o r f o l d s west of i t , and there has been more t h i c k e n i n g at the hinge and t h i n n i n g on the l i m b s . F o l d s have a t h i n n i n g r a t i o of about 1:4. Fold, hinges are a l s o somewhat sharper e a s t of the f a u l t than they are west of i t . The minor f o l d s are n e a r l y every-where repeated many times so t h a t t h e i r sense i s not c l e a r . J o i n t s The p a t t e r n of j o i n t i n g has been s t u d i e d i n some d e t a i l . Stereograms showing the p o l e s to j o i n t planes have been p l o t t e d f o r the metamorphic rocks east and west of Haggart Creek f a u l t . J o i n t s west of t h i s f a u l t c oncentrate around two p o i n t s a t 172/76 W and 58/60 SE. I t i s i n t e r e s t i n g to compare these w i t h 170/80 ¥ f o r the g r e a t c i r c l e on which p o l e s to f o l i a t i o n f o r t h i s a r e a p l o t and w i t h 48/66 SE f o r the g r e a t c i r c l e to which the c o n c e n t r a t i o n of the l a t e l i n e a t i o n (Phase II') i n t h i s a r e a i s the p o l e . (See f i g u r e 4-2) F i g u r e 44* Contoured stereogram of p o l e s to .joints i n  g r a n i t i c rocks east of Haggart Creek f a u l t . Lower Hemisphere equal area Schmid p r o j e c t . POLES TO JOINTS GRANITIC ROCKS EAST OF HAGGART CREEK FAULT | | 0 - 5»/c | 1 5-10 e/c 5 0 plotted • > io°/0 T 48. East of Haggart Creek f a u l t j o i n t s i n the metam-orphic rocks concentrate around 73/6? S and 170 /90 . The angle between Phase I plunge d i r e c t i o n and the pole to the strongest j o i n t set east of Haggart'Creek f a u l t i s 63 ° , which compares with 70° f o r the angle between Phase I plunge d i r -e c t i o n and the pole to the second strongest j o i n t set west of the f a u l t . (See f i g u r e 43) In the g r a n i t i c rocks east of Haggart Creek f a u l t are two j o i n t sets which concentrate around 90/70S and 0 / 9 0 . Though only a few j o i n t s were measured i n the g r a n i t i c rocks west of Haggart Creek f a u l t these seem to conform with the set 0 / 9 0 . (See f i g u r e 44} Conclusions Several conclusions can be drawn from the foregoing d e s c r i p t i v e s e c t i o n . 1. Only two phases of f o l d i n g (Phase I and Phase I I ) can be recognized i n the area. A phase of f o l d i n g e a r l i e r than Phase I may be p o s t u l a t e d to have produced the bedding plane f o l i a t i o n , but f o l d s of t h i s e a r l y phase would of nec-e s s i t y be i s o c l i n a l and recumbent and are unrecognizable. No minor f o l d s to support such an e a r l y i s o c l i n a l phase are found and l i n e a r s t r u c t u r e s , unless p a r a l l e l and i d e n t i c a l to Phase I l i n e a t i o n are l a c k i n g . I t i s p o s s i b l e that the f o l i a t i o n may a l s o have been formed by strong shearing p a r a l l e l to the o r i g i n a l bed-ding of the rock without much or any f o l d i n g . 2. The f i r s t o f the two phases of f o l d i n g , Phase I, i s by f a r the s t r o n g e s t f o l d i n g phase. I t has produced sub-i s o c l i n a l minor f o l d s (see f i g u r e s 38 , 39 , 40) on east t r e n d i n g axe s. 3 . The r e v e r s a l i n sense of Phase I minor f o l d s i n rocks west of Haggart Creek f a u l t suggests a l a r g e sub-i s o c l i n a l f o l d i n the micaceous q u a r t z i t e s west of Haggart Creek f a u l t ; t h i s s u g g e s t i o n i s supported by f o l i a t i o n trends h e r e . 4. l i n e a t i o n s of Phase 1 are p a r a l l e l to Phase I f o l d axes. 5 . Phase I f o l d i n g accounts f o r the v a r i a t i o n i n o r i e n -t a t i o n of f o l i a t i o n west of Haggart Creek f a u l t . 6. F o l i a t i o n o u t l i n e s a broad west p l u n g i n g a n t i f o r m east of Haggart Creek f a u l t . T h i s a n t i f o r m i s probably a Phase I s t r u c t u r e t h a t may have been m o d i f i e d by i n t r u s i o n of g r a n i t i c rocks i n i t s c o r e . 7. The q u a r t z i t e s n o r t h and south of the micaceous q u a r t z i t e s west of Haggart Creek f a u l t have been s u b j e c t e d to Phase I f o l d i n g , but Phase I f o l d axes i n these rocks have d i f f e r e n t o r i e n t a t i o n s from those i n the micaceous q u a r t z i t e s between them, because they are separated by f a u l t s from the micaceous r o c k s . The d i f f e r e n c e s i n o r i e n t a t i o n of f o l d axes of Phase I i n d i c a t e the movement that has o c c u r r e d on these f a u l t s . 5 0 . 8. J o i n t i n g i n the metamorphic rocks west of Haggart Creek f a u l t i s r e l a t e d to Phase I and Phase I I f o l d i n g . Two j o i n t s e t s are p r e s e n t . The predominant one by f a r i s a s e t of j o i n t s p e r p e n d i c u l a r to the plunge of Phase I l i n e a r s t r u c t u r e s and i s t h e r e f o r e r e f e r r e d to as a Phase I 'ac' j o i n t s e t . The weaker j o i n t s e t i s p e r p e n d i c u l a r to the plunge of Phase I I l i n e a r s t r u c t u r e s and i s c o n s i d e r e d as a Phase I I 'ac' j o i n t s e t . 9. A second weak phase (Phase I I ) of f o l d i n g has occ-u r r e d . Minor f o l d s of t h i s phase are w r i n k l e s t h a t plunge northwestward and have not a f f e c t e d the o v e r a l l a t t i t u d e of f o l i a t i o n to any marked degree. 1 0 . Two se t s of j o i n t s are developed i n g r a n i t i c rocks i n the map area. They do not c o i n c i d e w i t h those of the surround-i n g metamorphic rocks and are t h e r e f o r e c o n s i d e r e d to have dev-eloped as a r e s u l t of a separate s t r e s s p a t t e r n t h a t has not a f f e c t e d the metamorphic r o c k s . T h i s s t r e s s p a t t e r n may be r e l a t e d to c o o l i n g of the g r a n i t i c mass which r e s u l t e d i n f r a c -t u r i n g along two almost p e r p e n d i c u l a r p l a n e s . The two j o i n t s e t s do not show any obvious r e l a t i o n s h i p to the form of the g r a n o d i o r i t e i n t r u s i o n . 11. Two s e t s of j o i n t s are developed i n the metamorphic rocks e a s t of Haggart Creek f a u l t . By f a r the s t r o n g e s t of these i s c o n s i d e r e d to be the Phase I I 'ac 1 j o i n t s e t . The second s t r o n g e s t j o i n t s e t i s perhaps the Phase I 'ac' j o i n t 51. s e t . No e x p l a n a t i o n i s suggested f o r the t h i r d , v e r y weak, s e t of j o i n t s . 12. The f a c t t h a t Phase I I l i n e a t i o n i s l a c k i n g east o f Haggart Creek f a u l t and that the Phase I I 'ac' j o i n t s e t i s more prominent here than i t i s west of the f a u l t suggests t h a t thermal metamorphism has destroyed the Phase I I l i n e a t i o n , but tha t t h i s f o l d i n g phase has c e r t a i n l y a c t ed on these r o c k s and perhaps more s t r o n g l y than west of the f a u l t . T h i s i s a l s o supported by the tendency of p o l e s to f o l i a t i o n i n t h i s a rea to spread along the great c i r c l e whose pole c o i n c i d e s with where t h i s l i n e a t i o n should be were i t not destroyed. Phase I l i n e a t i o n s are a l s o l e s s common east of Haggart Creek f a u l t than they are west of i t . MAJOR STRUCTURES Fol d s That l a r g e s c a l e f o l d s are d i f f i c u l t to o u t l i n e i n the map a r e a i s due to the g e n e r a l l a c k of outcrop and marker h o r i z o n s . T h e i r presence i s however suggested by the nature and abundance of minor s t r u c t u r e s that occur i n the ar e a . The grey p h y l l i t e s west of Haggart Creek f a u l t out-l i n e what appears to be an east p l u n g i n g , recumbent synform, but the a c t u a l j u n c t i o n of the two grey p h y l l i t e bands was not observed so t h a t t h i s f o l d i s not a c e r t a i n t y . 52. Trends of f o l i a t i o n o u t l i n e an eastward p l u n g i n g f o l d i n the micaceous q u a r t z i t e s west of Haggart Creek and the o p p o s i t e senses o f minor f o l d s support t h i s . The reader i s r e f e r r e d to the accompanying trend map. Ea s t of Haggart Creek f a u l t trends of f o l i a t i o n out-l i n e a broad, open, westward p l u n g i n g a n t i f o r m . T h i s i s evident from the t r e n d map. The g r a n o d i o r i t e stock occupies i t s hinge or core and i t s shape appears i n a gen e r a l way to conform with the host rock s t r u c t u r e . The f a c t t h a t p o l e s to f o l i a t i o n i n t h i s a r e a f a l l a l ong a gr e a t c i r c l e whose pole c o i n c i d e s with the Phase I l i n e a t i o n suggests t h a t t h i s f o l d i s a Phase I s t r u c t u r e t h a t l o c a l i z e d i n f u s i o n of g r a n o d i o r i t e along i t s c o r e . F a u l t s S e v e r a l f a u l t s cut the area. The most important of these, the Haggart Creek f a u l t , has a l r e a d y f i g u r e d prominently i n the f o r e g o i n g d i s c u s s i o n . Other f a u l t s are' the T i n H i l l f a u l t and i t s c o u n t e r p a r t , the B l a c k P h y l l i t e f a u l t , the F i f t e e n Pup c r o s s - f a u l t , the Rex f a u l t , the S e c r e t Creek C r o s s - f a u l t , and the McGann Creek c r o s s - f a u l t . Of these only the Haggart Creek f a u l t , the Rex f a u l t , and the F i f t e e n Pup f a u l t have been observed. The oth e r f a u l t s do not crop out i n the area and t h e i r presence can only be i n f e r r e d from s t r u c t u r a l evidence. In the f o l l o w i n g s e c t i o n the f a u l t s are d e s c r i b e d and the evidence f o r t h e i r e x i s t e n c e i s s e t out. Aside from 53 these major f a u l t s s e v e r a l s m a l l e r f a u l t s have been observed. These l a t t e r ones are not d e s c r i b e d : t h e i r nature may be i n f e r r e d from the map, to which the reader i s r e f e r r e d through-out the f o l l o w i n g d i s c u s s i o n , a. Haggart Creek F a u l t The presence of t h i s f a u l t was i n f e r r e d from s t r u c -t u r a l evidence. A consequent search f o r some i n d i c a t i o n of the f a u l t on the ground r e s u l t e d i n the f i n d i n g of a bleached, s o f t gouge zone at l e a s t 20 f e e t wide i n the bottom of Haggart Creek, 1 m i l e below G i l l Gulch. The gouge zone has been ex-posed here by a 2 0-feet-wide p l a c e r c u t . Rocks on e i t h e r s i d e of the gouge zone were not exposed. The f a u l t f o l l o w s the v a l l e y of Haggart Creek a f t e r which i t has been named. I t seems l i k e l y t h a t the f a u l t l o c a l i z e d Haggart Creek. Evidence f o r the e x i s t e n c e of the f a u l t c o n s i s t s of the f o l l o w i n g . 1. Gouge Zone. 2 . Displacement of l i t h o l o g i c boundaries on e i t h e r side of the f a u l t . 3. Pronounced s t r u c t u r a l d i f f e r e n c e s on e i t h e r s i d e of the f a u l t i n the form of markedly d i f f e r e n t a t t i t u d e s of f o l i a t i o n , t r e n d s • o f Phase I minor f o l d plunges and l i n e a t i o n s and a t t i t u d e s of j o i n t s . 4. Displacement of the T i n H i l l - B l a c k P h y l l i t e f a u l t by the Haggart Creek f a u l t . 54 The dip of the f a u l t i s not known, nor can i t be i n f e r r e d from i t s outcrop p a t t e r n . The sense of movement on the f a u l t i s c o n s i d e r e d to be l a r g e l y d i p s l i p and down on the e a s t . The amount of movement estimated from the geo-l o g i c map i s of the order of one thousand f e e t . b. T i n H i l l F a u l t T h i s f a u l t crops out on the south s l o p e s of T i n H i l l e ast of Haggart Creek. The T i n H i l l f a u l t i s thought to be the e a s t e r n e x t e n s i o n of the B l a c k P h y l l i t e f a u l t , from which i t i s c u t o f f by Haggart Creek f a u l t . The f a u l t does not crop out anywhere, but i t s p r e -sence i s a g e o l o g i c n e c e s s i t y . North of the f a u l t , which trends somewhat n o r t h of ea s t , are b l a c k p h y l l i t i c r o c ks, which s t r i k e northwest and d i p n o r t h e a s t at moderate ang l e s . South of t h i s f a u l t are micaceous q u a r t z i t e s t h a t s t r i k e more or l e s s p a r a l l e l to the f a u l t and d i p moderately northwest. That the p o s i t i o n of the f a u l t i s not w e l l d e f i n e d i s due to the l a c k of outcrop on the south slope of T i n H i l l . How-ever i t s a c t u a l p o s i t i o n i s probably c l o s e to that shown on the map. The assumed outcrop p a t t e r n suggests a south dip of the f a u l t s u r f a c e . The movement on the f a u l t i s i n f e r r e d to be l a r g e l y r o t a t i o n a l or s c i s s o r - l i k e on the b a s i s of movement on the B l a c k P h y l l i t e f a u l t . c. Black P h y l l i t e F a u l t T h i s f a u l t , the c o u n t e r p a r t of the T i n H i l l f a u l t , d e s c r i b e d above, i s west of Haggart Creek. No outcrops o f i t 55. were seen, but i t s presence i s s t r u c t u r a l l y necessary and i t s p o s i t i o n i s l i m i t e d f a i r l y c l o s e l y by outcrops on e i t h e r side of i t a t two p l a c e s . The f a u l t trends southeast. North of i t are bla c k p h y l l i t i c rocks i n which f o l i a t i o n s d i p near v e r t i c a l and s t r i k e p a r a l l e l to the f a u l t while south o f i t micaceous quart-z i t e s s t r i k e p a r a l l e l to the f a u l t , but dip moderately n o r t h -e a s t . L i n e a t i o n s of Phase I n o r t h of the f a u l t t r end p a r a l l e l to i t and have no plunge, while l i n e a t i o n s south of the f a u l t plunge about 10°north of east a t roughly 20°. Prom t h i s i n f o r m a t i o n the movement on the f a u l t has ap p a r e n t l y been s c i s s o r l i k e w i t h r o t a t i o n of the no r t h e r n b l o c k e a s t up, west down, r e l a t i v e to the south block. The amount of movement must have been v a r i a b l e . Prom the outcrop p a t t e r n the dip of the f a u l t can be i n f e r r e d to be s t e e p l y to the south, d. Rex P a u l t Rex f a u l t , i n the southwest of the map area, i t s e l f o f f s e t by s e v e r a l o t h e r f a u l t s , trends roughly east and d i p s northward at an angle of about 60°. Good outcrops of the f o o t w a l l and hanging w a l l are a v a i l a b l e f o r study. S l i c k e n s i d e s on the f o o t w a l l i n d i c a t e that l a s t movement has been d i p s l i p almost e n t i r e l y and t h a t i t has been normal. Normal movement i s a l s o supported by the d i r e c t i o n of drag of f o l i a t i o n i n the w a l l rocks on the f o o t and hanging w a l l s . North of the f a u l t are micaceous q u a r t z i t e s which dip 56 northward moderately while the d i p south of the f a u l t i s pre-dominently more eastward a t s i m i l a r angles i n rocks t h a t are g e n e r a l l y l e s s micaceous than those n o r t h of the f a u l t . D i f f -erences i n plunge of Phase I l i n e a t i o n are a l s o noted, as des-c r i b e d above. The amount of movement on the Rex f a u l t i s not known. e. F i f t e e n Pup C r o s s - f a u l t F i f t e e n Pup c r o s s - f a u l t crops out a t one p l a c e i n the area. In a b u l l d o z e r cut n o r t h of F i f t e e n Pup a l i m o n i t e s t a i n e d gouge zone at l e a s t t h i r t y f e e t wide i s exposed. The w a l l s are not exposed and the d i p of the f a u l t and the move-ment on i t are not known. From the outcrop p a t t e r n of the f a u l t the dip i s a p p a r e n t l y n e a r l y v e r t i c a l . O f f s e t on the f a u l t i s thought to be l a r g e l y s t r i k e s l i p w i t h l a r g e r move-ment i n the south than i n the n o r t h where the f a u l t a p p a r e n t l y d i e s out. f . S e c r e t Creek F a u l t S e c r e t Creek f a u l t near the west edge of the area does not crop out i n the a r e a : i t s presence i s i n f e r r e d from d i s c o n t i n u i t y of l i t h o l o g i c u n i t s and apparent o f f s e t of the Rex v a u l t . I f movement has been d i p s l i p i t s magnitude must be of the o r d e r of t w e n t y - f i v e hundred f e e t , w i t h the east being the upthrown s i d e . I t i s s u r p r i s i n g to note t h a t the plunge of l i n e a r s t r u c t u r e s on e i t h e r s i d e of t h i s f a u l t has not been a f f -ected, whereas i t has been changed markedly by an a p p a r e n t l y 57 s m a l l e r movement i n the case of Haggart Creek f a u l t . The reason f o r t h i s seeming d i s c r e p a n c y may be t h a t the nature of the movement on the f a u l t was d i f f e r e n t on t h i s f a u l t than i t was on Haggart Creek f a u l t , g. McGann Creek F a u l t West of S e c r e t Creek i s yet another f a u l t , which trends about twenty degrees west of n o r t h and which, from i t s outcrop p a t t e r n must have a near v e r t i c a l d i p . The f a u l t does not crop out, but i t o f f s e t s Rex f a u l t and the two dykes of quartz f e l d s p a r porphyry. The amount of o f f s e t i s s m a l l e r i n the n o r t h than i t i s i n the south, an e f f e c t t h at may be due to the dying out of the f a u l t at i t s n o r t h end. I t seems l i k e l y t h a t movement has been l a r g e l y s t r i k e s l i p . TECTONIC HISTORY The t e c t o n i c h i s t o r y of the area can be deduced from the s t r u c t u r a l f e a t u r e s d e s c r i b e d above. I t i s presented i n c h r o n o l o g i c a l order below. 1. Phase I f o l d i n g to produce f o l d s on g e n t l y eastward t r e n d i n g axes. 2. Phase I I f o l d i n g , a v e r y weak phasermarked i n the west by a l i n e a t i o n and an 'ac' j o i n t s et a,nd i n the east by a w e l l developed s e t of 'ac' j o i n t s , d i d not a f f e c t the o r i e n t a t i o n of f o l i a t i o n much. 3. I n t r u s i o n of the g r a n i t i c stock east of Haggart Creek f a u l t . 58 k. F a u l t i n g , f i r s t i n a n e a s t d i r e c t i o n a l o n g two m a j o r f a u l t s w i t h v a r i o u s t y p e s o f m o v e m e n t a n d l a t e r i n a n o r t h d i r e c t i o n a l o n g two o t h e r f a u l t s t o d i s r u p t t h e w h o l e p a t t e r n , w i t h t h e w e s t e r n b l o c k m o v i n g u p r e l a t i v e t o t h e e a s t e r n one a n d p r o d u c i n g a m a r k e d c h a n g e i n p l u n g e i n P h a s e I l i n e a r s t r u c t u r e s . STRUCTURAL F I T WITH P A T T E R N S TO T H E SOUTH::. SOME I D E A S A b r i e f d e s c r i p t i o n o f s t r u c t u r a l f e a t u r e s t o t h e s o u t h o f t h e map a r e a i s g i v e n i n t h e f o l l o w i n g s e c t i o n . T h e s t r u c t u r e s a r e c o m p a r e d w i t h t h o s e i n t h e map a r e a . T h e b l o c k d i a g r a m ( A p p e n d i x I I I ) i n c o r p o r a t e s some i d e a s o f t h e g e n e r a l s t r u c t u r e o f t h e a r e a . M i n o r s t r u c t u r e s s o u t h o f t h e map a r e a a r e s i m i l a r t o t h o s e w i t h i n t h e a r e a i t s e l f . F o l i a t i o n n o r t h o f S o u t h M c Q u e s t e n r i v e r d i p s n o r t h w a r d a t s h a l l o w t o m o d e r a g e a n g l e s a s do t h o s e i n t h e map a r e a . P h a s e I l i n e a r s t r u c t u r e s i n t h e map a r e a a r e p a r a -l l e l t o t h o s e i n a r e a s t o t h e s o u t h a s f a r a s M c Q u e s t e n R i v e r , b u t p l u n g e i s g e n e r a l l y s h a l l o w e r t h a n i t i s i n t h e map a r e a . P l u n g e d i r e c t i o n r e v e r s a l s a r e o b s e r v e d t o t h e s o u t h a s t h e y a r e i n t h e map a r e a . P h a s e I m i n o r f o l d s s o u t h o f t h e map a r e a a n d n o r t h o f M c Q u e s t e n R i v e r a r e m o r e i s o c l i n a l t h a n t h o s e i n t h e map a r e a and t h e i r sense i s opposite to t h a t g e n e r a l l y observed i n the map a r e a . Phase I I l i n e a t i o n s are much commoner i n rocks to the south than they are i n the map area. Both the plunge and i t s d i r e c t i o n are constant from South McQuesten R i v e r to the map a r e a . J o i n t i n g i n areas south of the map area shows a p a t t e r n s i m i l a r to t h a t w i t h i n the area, the predominant s e t being the 'ac* j o i n t s of Phase I. Rocks south of the map area are s i m i l a r to those i n the area i t s e l f . C l o s e to South McQuesten R i v e r and n o r t h of i t Keno H i l l Q u a r t z i t e crops out. The s e c t i o n immediately n o r t h of 'South McQuesten R i v e r i s l i t h o l o g i c a l l y i d e n t i c a l to t h a t on Keno and Galena H i l l s and the s t r u c t u r a l l y h i g h e r , or more n o r t h e r n rocks are more or l e s s conformable on them. The p a r a l l e l i s m of Phase I minor s t r u c t u r e s from South McQuesten R i v e r to the map area i s c o n s i d e r e d evidence that these minor s t r u c t u r e s are g e n e t i c a l l y r e l a t e d . I t i s thought that the opposing sense of minor f o l d s ( n o r t h up and over south i n the map area and south up i n the v i c i n i t y of South McQuesten R i v e r ) i s evidence that the two areas are on opposite limbs of a l a r g e recumbent Phase I f o l d . 6o The abrupt change i n sense of Phase I minor folds across the Lynx Creek-Haggart Creek v a l l e y i s considered evidence f o r a possible f a u l t along this v a l l e y . Decreased i n t e n s i t y of Phase II f o l d i n g to the north i s thought to account f o r the progressive lack of Phase II structures i n areas successively further north. The centre of highest i n t e n s i t y of Phase II f o l d i n g i s thought to be i n the v i c i n i t y of South McQuesten River. The McQuesten a n t i c l i n e (Bostock 1 9 4 7 ) i s considered to be a f a u l t which has had a large amount of d i p s l i p movement on i t (south side up) rather than a f o l d . Opposing dips, north-ward north of thi s f a u l t and southward south of i t , are thought to be the re s u l t of thi s f a u l t . I t i s further considered that the McQuesten ' a n t i c l i n e ' i s of geologically recent o r i g i n and that minor structures i n the area are gen e t i c a l l y and tempor-a l l y unrelated to i t . METAMORPHISM GENERAL STATEMENT The rocks have been subjected to weak regional metamorphism and i n the eastern section a la t e phase of F i g u r e 4 5 . ACF diagram f o r q u a r t z - a l b i t e - m u s c o v i t e - c h l o r i t e — s u b f a c i e s of g r e e n s c h i s t r e g i o n a l metamorphic f a c i e s f o r rocks w i t h excess SiOp. Coloured  s e c t i o n s r e p r e s e n t assemblages found i n the a r e a . 6 1 . moderate thermal metamorphism has been superimposed on t h i s r e g i o n a l metamorphism. Metasomatism appears to be l i m i t e d to rocks c l o s e to g r a n i t i c c o n t a c t s . REGIONAL METAMORPHISM M i n e r a l assemblages i n the metamorphic rocks west of Haggart Creek f a u l t are very uniform. T y p i c a l assemblages a r e : Q u a r t z ^ m u s c o v i t e - c h l o r i t e - a l b i t e Q u a r t z - m u s c o v i t e = c h l o r i t e Quartz-museovite H o r n b l e n d e - a l b i t e - c h l o r i t e - s t i l p n o m e l a n e - q u a r t z These assemblages are c h a r a c t e r i s t i c of the g r e e n s c h i s t f a c i e s of r e g i o n a l metamorphism and f i t i n t o the qu a r t z - a l b i t e - m u s c o -v i t e - c h l o r i t e s u b f a c i e s . An ACE diagram f o r t h i s s u b f a c i e s i s reproduced i n f i g u r e 4 5 . E a s t of Haggart Creek f a u l t the t y p i c a l assemblage i n micaceous q u a r t z i t e s i s q u a r t z - b i o t i t e - m u s c o v i t e - c h l o r i t e -a l b i t e . T h i s assemblage f i t s the g r e e n s c h i s t f a c i e s and belongs i n the q u a r t z - a l b i t e - e p i d o t e - b i o t i t e - s u b f a c i e s . An AKE diagram f o r t h i s f a c i e s i s reproduced i n f i g u r e l 4 5 . '(\ 6 2 . The f a c t t h a t the metamorphic rocks east of Haggart Creek f i t a s l i g h t l y h i g h e r grade of r e g i o n a l metamorphism i s co n s i d e r e d due to the e f f e c t s o f thermal metamorphism on these rocks by i n t r u s i o n of the g r a n o d i o r i t e s t o c k . The o r i g i n o f the micaceous q u a r t z i t e s and p h y l l i t e s i s c l e a r . These low grade, r e g i o n a l l y metamorphosed rocks were o r i g i n a l l y impure sandstones and quartz r i c h s hales or s i l t s t o n e s . THERMAL METAMORPHISM Thermal metamorphism i s marked only east of Haggart Creek. The e f f e c t s of thermal metamorphism n o r t h and south of the g r a n o d i o r i t e stock are the same, but the thermal aureole i s narrower on the n o r t h s i d e of i t than i t i s on the south s i d e . North of the quartz d i o r i t e stock the f i r s t s i g n s of thermal metamorphism are i n d i c a t e d by the appearance of a n d a l u s i t e i n rocks a t l e a s t f i v e hundred f e e t from the g r a n i t i c c o n t a c t . The l i n e at which the f i r s t e f f e c t s of c o n t a c t metamorphism occur i s d i f f i c u l t to d e f i n e s i n c e low r e g i o n a l metamorphic assemblages are so s i m i l a r to low thermal metamorphic assemblages and the thermal metamorphic aureole grades i m p e r c e p t i b l y i n t o the normal low grade r e g i o n a l metamorphic zone. Assemblages of m i n e r a l s found i n the rocks near the stock are l i s t e d below with the f a c i e s of thermal metamorphism to which they belong. F i g u r e 46. AKF diagram f o r hornblende h o r n f e l s thermal  metamorphic f a c i e s rocks w i t h excess SiO?. Coloured s e c t i o n s r e p r e s e n t assemblages found i n the a r e a . 6 3 . Assemblages i n the A n d a l u s i t e H o r n f e l s U n i t M i n e r a l s are i n order of abundance i n which they occur i n each assemblage. 1. Q u a r t z - b i o t i t e - m u s c o v i t e . 2. Q u a r t z - b i o t i t e - m u s c o v i t e - a n d a l u s i t e . 3. B i o t i t e - m u s c o v i t e - a n d a l u s i t e . 4. Q u a r t z - c o r d i e r i t e - b i o t i t e . 5. Q u a r t z - a n d a l u s i t e - c o r d i e r i t e - b i o t i t e - s i l l i m a n i t e - m u s c o v i t e . 6. Q u a r t z - c o r d i e r i t e . 7. Biotite-muscovite-quartz-corundum. 8. Quartz-K-feldspar-muscovite-corundum-biotite. The f i r s t s i x of these assemblages belong to the h o r n b l e n d e - h o r n f e l s f a c i e s f o r which the AKF diagram i s r e -produced i n f i g u r e 4 6 . S e v e r a l c o n c l u s i o n s can be drawn from t h i s i n f o r m a t i o n . The assemblages are a l l i r o n d e f i c i e n t and s i l i c a r i c h . They are d e r i v e d from quartz r i c h , p e l i t i c and a r k o s i c rocks and are of s i m i l a r chemical composition to the rocks west of Haggart Greek f a u l t with which they are probably c o r r e l a t i v e s . But f o r s m a l l d i s c r e p a n c i e s a l l the assemblages f i t i n the hornblende-hornf e l s f a c i e s : t h i s i n d i c a t e s a uniform temperature d i s t r i b u t i o n d u r i n g thermal metamorphism. A c o r o l l a r y of the f a c t t h a t the assemblages f i t one f a c i e s w e l l i s t h a t e q u i l i b r i u m c o n d i t i o n s were reached d u r i n g thermal metamorphism. The presence of s i l l i m a n i t e i n some assemblages from 64 rocks very c l o s e to the g r a n i t i c c o n t a c t i n d i c a t e s t h at s l i g h t l y h i g h e r temperature c o n d i t i o n s e x i s t e d here. The lowest f a c i e s i n which s i l l i m a n i t e appears i s the i n t e r m e d i a t e or t r a n s i t i o n a l f a c i e s "between the hornblende-hornf e l s and almandine-amphibolite f a c i e s (Turner 1948). Corundum occurs i n some of the rocks c l o s e to the g r a n i t i c c o n t a c t : two assemblages are g i v e n above. Both these assemblages are d i f f i c u l t to a s s i g n to any s i n g l e f a c i e s . Except f o r corundum the m i n e r a l s of these assemblages are char-a c t e r i s t i c of the h o r n b l e n d e - h o r n f e l s f a c i e s . Corundum i t s e l f i s c h a r a c t e r i s t i c o f a h i g h e r f a c i e s , the pyroxene h o r n f e l s f a c i e s , but the other m i n e r a l s i n the two assemblages do not f i t i n t h i s f a c i e s . The f a c t t h a t corundum occurs o n l y near the g r a n o d i o r i t e s t o c k r u l e s out the p o s s i b i l i t y t h a t t h i s m i n e r a l i s of d e t r i t a l o r i g i n and i m p l i e s t h a t i t i s a thermal metemorphic m i n e r a l . In both the assemblages l i s t e d above corundum occurs w i t h quartz, sometimes i t i s even i n c o n t a c t with t h a t m i n e r a l , although i n g e n e r a l the corundum i s s u r -rounded by muscovite. These d i s c r e p a n c i e s are d i f f i c u l t to r e s o l v e . I t i s suggested t h a t the corundum formed metastably and i n d i c a t e s a tre n d to h i g h e r temperatures than those i n d i c a t e d by the horn-blende-hornf e l s f a c i e s near the g r a n o d i o r i t e c o n t a c t . R e t r o g r e s s i v e metamorphism has occu r r e d i n some p a r t s F i g u r e 47. ACF diagram f o r thermal metamorphic hornblende h o r n f e l s rocks w i t h excess SiOp. C o l o u r e d " s e c t i o n s r e p r e s e n t assemblages found i n the  a r e a . 65 of the aureole while i n others i t i s t o t a l l y l a c k i n g . Some t h i n s e c t i o n s of a n d a l u s i t e h o r n f e l s e s r e v e a l completely f r e s h a n d a l u s i t e while other s e c t i o n s show t h a t t h i s m i n e r a l has been r e p l a c e d to a l a r g e e x t e n t by muscovite. Corundum g e n e r a l l y shows rims of muscovite. These rims are c o n s i d e r e d of r e t r o g r e s s i v e o r i g i n . Why some rocks s h o u l d be completely f r e s h while others are a l t e r e d i s not known. There does not appear to be any s p a t i a l r e l a t i o n s h i p of the r e t r o g r a d e a l t e r -a t i o n to the g r a n i t i c c o n t a c t . I t i s suggested t h a t r e t r o g r a d e metamorphism i s brought about by potash metasomatism r e s u l t i n g i n the f o r m a t i o n of muscovite from a n d a l u s i t e and corundum. Quartz D i o p s i d e H o r n f e l s U n i t Assemblages 1 . Quartz-tremolite-corundum. 2. Q u a r t z - b i o t i t e - t r e m o l i t e . 3. Q u a r t z - d i o p s i d e - e p i d o t e - c a l c i t e - c h l o r i t e . k. C a l c i t e - d i o p s i d e - t r e m e l i t e - q u a r t z - o l i g o c l a s e . 5. Q u a r t z - d i o p s i d e - c a l c i t e . 6. Q u a r t z - d i o p s i d e - b i o t i t e - t r e m o l i t e - m u s c o v i t e . 7. Q u a r t z - p l a g i o c l a s e - c h l o r i t e - d i o p s i d e . 8. D i o p s i d e - q u a r t z - c a l c i t e - h o r n b l e n d e - t r e m o l i t e . These assemblages f i t the h o r n b l e n d e - h o r n f e l s f a c i e s of thermal metamorphism f a i r l y w e l l . F i g u r e k7 shows the ACF diagram f o r t h i s f a c i e s . I t i s e v i d e n t t h a t the assemblages are of e n t i r e l y d i f f e r e n t chemical composition from those d e s c r i b e d above. 66 The rocks are r i c h i n s i l i c a , lime and magnesia; they are a l s o alumina d e f i c i e n t . O r i g i n a l l y these rocks were impure l i m e s t o n e s . Apparent d i s c r e p a n c i e s due to the presence of some m i n e r a l s i n the assemblages, which do not f i t the f a c i e s , need an e x p l a n a t i o n . Corundum i s c o n s i d e r e d to i n d i c a t e a tendency to development of a h i g h e r f a c i e s and i s thought to have dev-eloped metastably. That the presence of t h i s m i n e r a l i n these odd a s s o c i a t i o n s does not f i t any f a c i e s p r e v i o u s l y d e s c r i b e d has a l r e a d y been e l a b o r a t e d upon. Ep i d o t e occurs i n some assem-blages:; i t i s thought to be of r e t r o g r e s s i v e o r i g i n . The same e x p l a n a t i o n i s o f f e r e d f o r the presence of c h l o r i t e i n some assemblages. Both these m i n e r a l s occur as s m a l l , sub-h e d r a l g r a i n s t h a t appear to be l a t e r than the other m i n e r a l s i n the r o c k s . O l i g o c l a s e occurs i n some r o c k s : i t s composi-t i o n does not f i t f o r the f a c i e s and the m i n e r a l i s thought to be an o r i g i n a l c o n s t i t u e n t of the r o c k r a t h e r than a meta-morphic m i n e r a l . In a d d i t i o n to the assemblages l i s t e d above most of those l i s t e d f o r the a n d a l u s i t e h o r n f e l s u n i t occur i n the quartz d i o p s i d e h o r n f e l s u n i t i n i t s p e l i t i c and q u a r t z - r i c h members. I t has a l r e a d y been demonstrated t h a t these p e l i t i c assemblages a l s o belong i n the h o r n b l e n d e - h o r n f e l s f a c i e s . South of the stock, beds with these assemblages occur 67 at l e a s t as f a r as f i v e thousand f e e t from g r a n i t i c outcrops but the t r u e d i s t a n c e to g r a n i t i c rocks i s much l e s s (about f i v e hundred f e e t ) . From f i g u r e 22 i t i s e v i d e n t t h a t the gran-i t i c c o n t a c t , which d i p s southward and p a r a l l e l to the h i l l -s i d e , i s c l o s e to the ground s u r f a c e . METASOMATISM Although tourmaline occurs i n most of the rocks around the g r a n o d i o r i t e stock, i t i s not c e r t a i n whether t h i s i s i n d i -genous o r i n t r o d u c e d . C e r t a i n l y there i s s c h o r l i t e i n n e a r l y a l l rocks i n the are a . There appears to be a h i g h e r propor-t i o n of s c h o r l i t e i n rocks c l o s e to the c o n t a c t than i n rocks f a r removed ftom i t . West of Haggart Creek f a u l t s c h o r l i t e occurs i n some p l a c e s i n i n d i v i d u a l , p r i s m a t i c c r y s t a l s up to 2 cm. l o n g on s e r i c i t i z e d f o l i a t i o n pla,nes i n the metamorphic rocks near c o n t a c t s w i t h g r a n i t i c r o c k s . I t has been suggested elsewhere t h a t potash metaso-matism accompanied r e t r o g r a d e metamorphismj i n f a c t i t may be tha t potash metasomatism was the cause of the r e s t r i c t e d amount of r e t r o g r e s s i v e metamorphism t h a t has oc c u r r e d i n the area around the g r a n o d i o r i t e s t o c k . TEMPERATURES AND PRESSURES DURING METAMORPHISM The approximate temperatures and pressure to which TEMPERATURE in 0 C ^ 200 400 600 800 F i g u r e 48. Diagram to show the l i m i t s of the temperature and pressure range d u r i n g thermal metamorphism.  The diagram i n d i c a t e s a temperature i n the  r e g i o n of 600°C and a depth of cover of about  12 km. a t the time of i n t r u s i o n of the grano-d i o r i t e s t o c k . 68 the rocks i n the ar e a have been s u b j e c t e d can be estimated from the types and grades of metamorphism which they show. The s t a b i l i t y f i e l d f o r assemblages belonging to the g r e e n s c h i s t f a c i e s ranges i n temperature from about 150°C to 400°C and i n rock pressure from an e q u i v a l e n t of 15 km. to about 25 km. The s t a b i l i t y f i e l d f o r the thermal metamorphic horn-blende-hornf e l s f a c i e s ranges from temperatures of 200°to 7 °0 OC. Rock p r e s s u r e s range up to an e q u i v a l e n t of 20 km. A n d a l u s i t e has a s t a b i l i t y f i e l d which ranges up to 5QQ°C and 20 km. of rock p r e s s u r e . The presence of s i l l i m a n i t e near the c o n t a c t of the g r a n o d i o r i t e s t o c k suggests t h a t a temperature i n excess of 300°C" and a rock pressure of an e q u i v a l e n t of at l e a s t 10 km. must have been reached. Corundum i s s t a b l e a t temperatures i n excess of 600°C. These data l i m i t the temperature of the g r a n o d i o r i t e stock at the time of i n t r u s i o n to above 600°C. The depth a t which the stock was i n t r u d e d i s probably about 12 km. (See f i g u r e 48) AGE RELATIONS Regional metamorphism i s thought to have accompanied f o l d i n g . I n t r u s i v e rocks are l a t e r than t h i s f o l d i n g as they Figure 4 9 * Peso S i l v e r Mines Gamp looking north. Mote surface s t r i p p i n g on number One vein i n r i g h t  foreground and adit to crosscut near dump i n l e f t foreground. 69. cut a c r o s s s t r u c t u r a l trends and are e n t i r e l y u n f o l i a t e d . Thermal metamorphism i s s p a t i a l l y r e l a t e d to the g r a n i t i c i n -t r u s i o n , as i s metasomatism. These f a c t s i n d i c a t e t h a t r e g -i o n a l metamorphism preceded thermal metamorphism. The evidence i s not c l e a r as to whether r e g i o n a l met-amorphism accompanied both Phase I and Phase I I f o l d i n g . That most of i t preceded Phase I i s i m p l i e d by the p a r a l l e l i s m of bedding and f o l i a t i o n and metamorphic r e c r y s t a l l i z a t i o n a long bedding. I t seems l i k e l y from the nature of the Phase I I s t r u c -t u r e s which are open and which do not have r e c r y s t a l l i z a t i o n a s s o c i a t e d with them, that r e g i o n a l metamorphism was complete before t h i s f o l d i n g o c c u r r e d . There i s no evidence to suggest t h a t potash metasoma-tism o c c u r r e d at any time other than a f t e r thermal metamorphism. ANTIMONY-SILVER-LEAD VEINS GENERAL STATEMENT What f o l l o w s i s a d e s c r i p t i o n of the m i n e r a l i z a t i o n that occurs i n the a n t i m o n y - s i l v e r - l e a d v e i n s west of Haggart Greek f a u l t . D e s c r i p t i o n s of the v e i n s are n e c e s s a r i l y b r i e f , s i n c e i n most cases only scant s u r f a c e i n f o r m a t i o n i s a v a i l a b l e . 7 0 . L i m i t e d underground work has been done on o n l y one of the v e i n s ; most specimens s t u d i e d are of o x i d i z e d s u r f a c e m a t e r i a l . D e s c r i p t i o n s of m i n e r a l d e p o s i t s e a s t of Haggart Creek f a u l t are not i n c l u d e d s i n c e only o x i d i z e d m a t e r i a l from dumps of o l d a d i t s and d r i f t s i s a v a i l a b l e . No r e c e n t work has been done on these d e p o s i t s . D e s c r i p t i o n s of the d e p o s i t s e a s t of Haggart Creek f a u l t are i n c l u d e d i n G.S.C. r e p o r t s . No shipments of ore have been made from any of the lode occurrences i n the map area. Pour v e i n s , the number One, Two, Three and Rex V e i n crop out west of Haggart Creek f a u l t . Of the f o u r v e i n s , three - the number One, Two and Three v e i n s , are very s i m i l a r i n mineralogy and may be p a r t s of the same v e i n system, while the f o u r t h - the Rex v e i n , has somewhat d i f f e r e n t mineralogy from these three and i s s t r u c t u r a l l y u n r e l a t e d to them. M i n e r a l i z a t i o n i n the number One, Two and Three v e i n s c o n s i s t s of p y r i t e , a r s e n o p y r i t e , jamesonite, galena, c h a l c o -p y r i t e and t e t r a h e d r i t e i n a gangue of s i d e r i t e . Secondary min-e r a l s i n these three v e i n s are l i m o n i t e (mostly g o e t h i t e ) , s c o r o d i t e , b i n d h e i m i t e , a n g l e s i t e , c o v e l l i t e , m alachite and c h a l c o c i t e . The r e l a t i v e abundance of m i n e r a l s i s v a r i a b l e from one v e i n to another. 71 Rex vein mineralization consists of jamesonite, galena, tetrahedrite, sphalerite and pyrite i n a gangue of s i d e r i t e . The secondary minerals are limonite, bindheimite, anglesite and c o v e l l i t e . NUMBER ONE VEIN Number One vein i s exposed on surface i n bulldozer trenches f o r a length of 800 feet and i t has been d r i f t e d on underground for a length of 600 feet. For i t s location see the accompanying map. The vein i s sinuous and i t s width varies from a maximum of about t h i r t y feet to l e s s than one foot. Average st r i k e of the vein i s about N20°E i n the south and N60°E further north; the dip i s to the northwest at angles of 50° or more i n the south and 40° or less i n the north. Movement on the vein f a u l t was normal, the amount of movement i s not known, but i s thought to have been small. There i s some evidence of post-mineralization movement, but this has been s l i g h t . The vein i s a more or l e s s regularly mineralized zone of brecciated and fractured host rock, that i s bounded on both sides by well defined, more or l e s s p a r a l l e l f a u l t s . M i neralization i s f o r the most part concentrated near the walls and the footwall i s generally favoured i n t h i s respect. Mineralization i s generally more massive i n thick sections of the vein. Replacement along the walls has been s l i g h t where i t i s seen. In most cases the only recognizable a l t e r a t i o n of 72 the w a l l rock i s s i l i c i f i c a t i o n . Some impregnation of the w a l l s by p y r i t e i s n o t i c e a b l e . The d r i f t on the v e i n has an average of about a hundred f e e t of backs and at t h i s l e v e l the v e i n i s s t r o n g l y o x i d i z e d l o c a l l y , although f o r the most p a r t secondary m i n e r a l s are absent. Secondary a l t e r a t i o n on the s u r f a c e has been i n t e n s e and the o n l y primary m e t a l l i c c o n s t i t u e n t s r e c o g n i z a b l e are a r s e n o p y r i t e , p y r i t e and jamesonite. Secondary m i n e r a l s make up more than e i g h t y percent of the m i n e r a l i z a t i o n a t the sur-f a c e . I t i s thought that s i l v e r at the s u r f a c e i s a s s o c i a t e d w i t h b i n d h e i m i t e . Lead at the s u r f a c e i s re p r e s e n t e d by angle-s i t e and bind h e i m i t e and the antimony v a l u e s are a l l h e l d i n b i n d h e i m i t e . Movement of metals has not been e x t e n s i v e i n the ex-p l o r e d p a r t s of the number One v e i n . S i l v e r to l e a d r a t i o s (5.2: 1) and s i l v e r to l e a d and antimony r a t i o s (3»3* 1) are more or l e s s c o n s t a n t . Copper i s the only metal t h a t has d e f i n i t e l y been mo b i l e . No copper m i n e r a l i z a t i o n i s e v i d e n t i n s u r f a c e trenches, while there i s a c o n s i d e r a b l e p r o p o r t i o n of c h a l c o -p y r i t e i n the m i n e r a l i z a t i o n exposed i n the d r i f t . The pre -sence o f c o n s i d e r a b l e c o v e l l i t e , c h a l c o c i t e and m a l a c h i t e i n some p a r t s of the d r i f t suggests t h a t there has been some super-gene enrichment i n copper a t t h i s l e v e l . F i g u r e 50. P y r i t e (Py) and a r s e n o p y r i t e (Apy) showing  euhc d r a l h a b i t enclosed by anhedral p y r i t e . 1 - N i c o l . x 2 5 . F i g u r e 5 1 . Two h a b i t s of p y r i t e (Py) euhedral g r a i n s and aggregates of anhedral g r a i n s . S i d e r i t e (s) shows same replacement t e x t u r e s to both  p y r i t e h a b i t s . N o t e ' l a y e r i n g 1 i n the aggregate of anhedral b y r i t e . 1 - N i c o l . x 6 6 . 73. Number One v e i n c o n t a i n s the f o l l o w i n g primary m i n e r a l s : P y r i t e 48$ A r s e n o p y r i t e 1 5 $ Jamesonite 1 5 $ C h a l c o p y r i t e 1 0 $ S i d e r i t e 1 0 $ T e t r a h e d r i t e 2$ I t i s e s timated that hydrothermal m i n e r a l s make up between one-fourth and one-half o f the volume of the e n t i r e v e i n . Textures The t e x t u r e s e x h i b i t e d by the hydrothermal m i n e r a l s of number One v e i n are d e s c r i b e d i n the f o l l o w i n g s e c t i o n . P y r i t e and a r s e n o p y r i t e show two h a b i t s . The most common h a b i t i s as aggregates of f i n e , a n hedral, equant g r a i n s l e s s than . 0 5 mm. a c r o s s . Such aggregates are o f t e n e l l i p -s o i d a l i n shape and show a l a y e r i n g or banding of g r a i n s i n many ca s e s . Both these m i n e r a l s a l s o occur l e s s commonly as euhedral c r y s t a l s .2 mm. a c r o s s . I t i s thought that these two h a b i t s f o l l o w e d one another c l o s e l y i n the emplacement sequence, f o r replacement t e x t u r e s of l a t e r m i n e r a l s are the same f o r both h a b i t s . No t e x t u r e s suggesting the sequence of d e p o s i t i o n of p y r i t e and a r s e n o p y r i t e have been noted. A r s e n o p y r i t e from number One v e i n c o n t a i n s t r a c e s of antimony and manganese. F i g u r e 52. Massive .jamesonite showing p a r a l l e l i n t e r - growth of coarse p r i s m a t i c g r a i n s and drag- n o s t i c b a s a l cleavage along which secondary  a l t e r a t i o n i s l o c a l i z e d .  X - N i c o l s . x 25. 74. Jamesonite i s d e f i n i t e l y l a t e r than p y r i t e f o r i t sometimes occurs i n v e i n l e t s which c u t t h a t m i n e r a l . In number One v e i n jamesonite occurs as massive aggregates of intergrown, p a r a l l e l o r i e n t e d , p r i s m a t i c g r a i n s . G r a i n l e n g t h s are commonly as much as 5 mm* Jamesonite a l s o occurs as s c a t t e r e d , a c i c u l a r c r y s t a l s of s i m i l a r l e n g t h , randomly o r i e n t e d i n s i d e r i t e . T h i s second type of jamesonite can be c o n s i d e r e d as e i t h e r newly i n t r o d u c e d w i t h s i d e r i t e , or i t can be i n t e r p r e t e d as r e m o b i l i z e d jamesonite. No evidence f o r e i t h e r e x p l a n a t i o n i s seen, but the second i n t e r p r e t a t i o n i s p r e f e r r e d . The l a t e jamesonite i s un-v e i n e d and no replacements of i t are found. Late jamesonite i s c o n s i d e r e d the f i n a l i n t r o d u c e d m i n e r a l . An X-ray powder photograph of jamesonite from each of the f o u r v e i n s has been made and the r e s u l t s are g i v e n i n the accompanying t a b l e . (Table 1) S p e c t r o g r a p h i c analyses of these jamesonites are i n c o r p o r a t e d i n t h i s t a b l e . I t i s e v i d e n t t h a t the v a r i a t i o n i n d spacings i s not a p p a r e n t l y systematic and t h a t no c o r r e l a t i o n between minor c o n s t i t u e n t s and d spacings i s obvious. C h a l c o p y r i t e i s a p p a r e n t l y l a t e r than jamesonite. The m i n e r a l occurs i n anhedral, i r r e g u l a r masses commonly 1 mm. or so a c r o s s i n s i d e r i t e or jamesonite. The cleavage of jame-s o n i t e appears to have exerted c o n s i d e r a b l e c o n t r o l on the l o c -a l i z a t i o n of c h a l c o p y r i t e , f o r examples of l a t h s or "peninsulas* of c h a l c o p y r i t e i n jamesonite are p l e n t i f u l . TABLE 1 Jamesonite (4PbS. PeS. 3 S D 2 S 5 ) (from each of the f o u r v e i n s a t S e c r e t Greek) d(obs) d(obs) d(obs) d(obs) d(obs) I No.l No.2 No.3 Rex tierry & Thompson ( h k l ) 1/2 6.00 6.15 6.03 6.10 6.03 (220) 1/2 5.01 5.04 5.09 5.09 5.10 (310) 7 4.06 4.11 4.10 4.14 4.10 (240) 8 3.81 3.87 3.87 3.91 3-87 (400) 10 7 3.42 3.09 3.44 3.09 3.46 3 .09 3.46 3.11 3.44 3.09 ( 2 5 0 2 ( 2 3 D(321) (350)(510) 1 2.93 2.96 2.98 2.98 2.95 (260) 6 2.82 2.84 2.84 2.84 2.84 ( 4 1 1 ) ( 3 3 D 8 2.71 2.74 2.72 2.75 2.75 ( 4 H ) ( 4 5 0 ) 2 2 . .2,29 2.23 2.29 2.24 2.29 2.24 2.31 2.25 2.30 2.24 (6402 (470K171) (560)(171) 1/2 2 2.16 2.05 2.19 2.07 2.16 2.06 2.17 2.06 2.16 2.06 (380)(271) 5 2.03 2.03 2.02 2.02 2.02 (740)(660) 1/2 1.961 1.969 1.965 1 1.904 1.914 1.907 1/2 1.860 1.873 1.866 2 1.828 1.836 1.831 1/2 1.716 1.725 1.725 Ag Cu Sn As B i Ag Cu Sn As B i B i As Ag Cu Sn Ag Sn Cu Zn Trace c o n s t i t u e n -from Spectrograpl A n a l y s e s . ( i n dc c r e a s i n g order oj abundance) 75 S i d e r i t e , the gangue m i n e r a l , appears to have been i n t r o d u c e d i n two stages. E a r l y s i d e r i t e i s coarse g r a i n e d and brownish y e l l o w i n c o l o u r , w h ile the l a t e s i d e r i t e i s f i n e r g r a i n e d and l i g h t e r c o l o u r e d and o c c a s i o n a l l y has r e -m o b i l i z e d ? jamesonite i n i t . The two d i f f e r e n t stages of s i d e r i t e emplacement are separated by a p e r i o d of b r e c c i a t i o n , probably due to minor renewed movement on the v e i n f a u l t . A l l the m i n e r a l s mentioned except l a t e jamesonite are b r e c c i a t e d and the f r a c t u r e s have been f i l l e d w i t h l a t e s i d e r i t e . In some cases matching bound-a r i e s are seen, i n d i c a t i n g that movement was only s l i g h t . E a r l y s i d e r i t e f i l l s f r a c t u r e s i n the v e i n b r e c c i a and the a n g u l a r i t y and s i z e of t h i s v e i n b r e c c i a i n d i c a t e s that the i n i t i a l movement on the v e i n was a l s o s m a l l . A few i n s t a n c e s of l a t e s i d e r i t e c u t t i n g e a r l y s i d e -r i t e are found. Whether the second s i d e r i t e was r e m o b i l i z e d e a r l y s i d e r i t e or newly i n t r o d u c e d s i d e r i t e i s not known, but the r e m o b i l i z e d theory i s favoured. The mechanism t h a t i n -duced r e m o b i l i z a t i o n may have been the heat generated or i n -troduced d u r i n g the second stage .of b r e c c i a t i o n of the v e i n . T e t r a h e d r i t e i s c o n s i d e r e d to have been emplaced du r i n g the e a r l y stage of s i d e r i t e i n t r o d u c t i o n and bef o r e second b r e c c i a t i o n o f the v e i n occurred. T h i s m i n e r a l i s o f t e n f r a c t u r e d and v e i n e d with l a t e s i d e r i t e . No t e x t u r a l r e l a t i o n -76 s h i p s between t e t r a h e d r i t e and other m e t a l l i c m i n e r a l s are seen, because t e t r a h e d r i t e always occurs as l a r g e , anhedral, equant, b r e c c i a t e d g r a i n s or aggregates o f g r a i n s i n s i d e r i t e . Such g r a i n s are commonly 1 cm. or more a c r o s s ; i n d i v i d u a l b r e c c i a t e d fragments are much s m a l l e r and reach a minimum of .1 mm. An X-ray powder photograph of t e t r a h e d r i t e from Number One v e i n gave a c e l l edge of 1 0 . 5 8 ( 8 ) ^ . T h i s value i s c o n s i d -e r a b l y h i g h e r than t h a t of o r d i n a r y t e t r a h e d r i t e (10.37 and i n d i c a t e s a h i g h s i l v e r content f o r the m i n e r a l . Quartz occurs s p a r i n g l y i n the v e i n and i s c o n s i d e r e d to be a l a t e stage gangue m i n e r a l . C r y s t a l s show the h a b i t t y p i c a l of a l p h a quartz and are commonly one or two cm. l o n g . Quartz c r y s t a l s occur only i n l a t e s i d e r i t e . Secondary A l t e r a t i o n Secondary a l t e r a t i o n i n number One v e i n has been ex-t e n s i v e . M i n e r a l s t h a t have developed at and near the s u r f a c e are g i v e n below with t h e i r r e l a t i v e p r o p o r t i o n s : G o e t h i t e 35$ A n g l e s i t e 15$ Bindheimite 30$ S c o r o d i t e 12$ C o v e l l i t e 1$ C h a l c o c i t e 5$) ) Found only underground M a l a c h i t e 1$) Figure 53. Goetfrite a l t e r a t i o n c o n t r o l l e d by rhombo-hedr a l cleavage of s i d e r i t e r e s u l t i n g i n  open boxworks. l - M c o l . x 2 5 . 77. These secondary m i n e r a l s are c h a r a c t e r i s t i c a l t e r -a t i o n m i n e r a l s of the assemblage of primary m i n e r a l s of the v e i n . No j a r o s i t e s have been r e c o g n i z e d so f a r . A l t e r a t i o n i s g e n e r a l l y c o n t r o l l e d by the s t r u c t u r e of the primary m i n e r a l s . Jamesonite a l t e r a t i o n i s s t r o n g l y c o n t r o l l e d by the cleavage i n t h a t m i n e r a l . G-oethite i s i n boxworks t h a t are pseudomorphous a f t e r s i d e r i t e and mimetic a f t e r the cleavage i n t h a t m i n e r a l . C o v e l l i t e l i n e s b r e c c i a t i o n cracks i n the primary m i n e r a l s , mainly t e t r a h e d r i t e and c h a l c o p y r i t e . S c o r o d i t e forms embayments i n a r s e n o p y r i t e t h a t are not con-t r o l l e d markedly by f r a c t u r e s or cleavage. The m i n e r a l occurs as p a l e , l e e k green, earthy masses that are sometimes s t a i n e d brown due to g o e t h i t e admixtures. A s p e c t r o g r a p h i c a n a l y s i s of s c o r o d i t e gave As and Ee as the major c o n s t i t u e n t s w i t h t r a c e s of Sb,Pb, Ag, Cu, Zn, A l i n d e c r e a s i n g order of abun-dance . C h a l c o c i t e forms s o f t , b l a c k , sooty c o a t i n g s on p y r i t e g r a i n s and i s found only underground i n the d r i f t on number One v e i n . Paragenesis The p a r a g e n e t i c sequence of the hydrothermal and secondary m i n e r a l s i s c l e a r from the f o r e g o i n g d e s c r i p t i o n s of t e x t u r e s . A Van de Veer diagram showing the paragenesis i s F i g u r e 54» Van de Veer diagram to show p a r a g e n e s i s o f p r i m a r y and secondary m i n e r a l s o f number One v e i n . N U M B E R O N E V E I N van de v e e r par age net ic diagram 78 i n c l u d e d i n f i g u r e 5^ . T h i s diagram a l s o shows r e l a t i v e pro-p o r t i o n s o f the h y d r o t h e r m a l l y i n t r o d u c e d and secondary m i n e r a l s . Temperature of D e p o s i t i o n and C l a s s i f i c a t i o n Wo good temperature of d e p o s i t i o n can be e s t a b l i s h e d f o r geothermometric data. A maximum temperature of d e p o s i t i o n i s g i v e n by the presence of alpha quartz, which i n v e r t s to beta quartz, a t 5 7 3 ° C The m e l t i n g p o i n t of jamesonite, 6 lO°C, gi v e s a s i m i l a r maximum. The d i s s o c i a t i o n temperature of s i d e -r i t e , 282°C, g i v e s a maximum temperature above which the v e i n cannot have been heated s i n c e emplacement of th a t m i n e r a l . The a r s e n o p y r i t e geothermometer was employed to o b t a i n a temperature of d e p o s i t i o n of t h a t m i n e r a l . A temperature below 300°C was obtained from a s p a c i n g of (203)=1.6304. (The c o r r e c t n e s s of t h i s geothermometer has been questioned r e c e n t l y , so t h a t l i t t l e f a i t h can be p l a c e d i n the temperature obtained.) The v e i n i s c l a s s i f i e d as a mesothermal c a v i t y f i l l i n g d e p o s i t , formed a f t e r b r e c c i a t i o n of the hos t rock. The e a r l y m i n e r a l s , a r s e n o p y r i t e and p y r i t e , i n d i c a t e a tendency toward hypothermal c o n d i t i o n s at the be g i n n i n g of the d e p o s i t i o n a l p e r i o d . NUMBER TWO VEIN Number Two v e i n l i e s n o r t h e a s t of number One v e i n . F i g u r e 55. Anhedral g r a i n s of a r s e n o p y r i t e (Apy) enclosed  by coarse g r a i n e d p a r a l l e l intergrowths of  "Jamesonite* I n c i p i e n t secondary a l t e r a t i o n s  along g r a i n boundaries i s e v i d e n t *  1 - N i c o l . x 25. 79. The a t t i t u d e and width of the v e i n i s s i m i l a r to t h a t of number One v e i n . The s t r i k e of number Two v e i n i s about N70°E and i t s d i p i s roughly 5 ° ° "to the northwest. Number One and number Two v e i n s are c o n s i d e r e d p a r t of one system and i t i s thought t h a t number Two v e i n may be the o f f s e t e x t e n s i o n of number One v e i n . No underground work or d r i l l i n g has been done on the v e i n and the only information, a v a i l a b l e i s from b u l l d o z e r trenches across the v e i n at v a r i o u s i n t e r v a l s . Number Two v e i n i s m i n e r a l o g i c a l l y s i m i l a r to number One v e i n , however propor-t i o n s o f m i n e r a l s v a r y as i s e v i d e n t from the l i s t s of primary m i n e r a l s . The primary m i n e r a l s i n number Two v e i n are present i n the f o l l o w i n g p r o p o r t i o n s : A r s e n o p y r i t e 3 0 $ Jamesonite 63$ P y r i t e 5 $ C h a l c o p y r i t e 1$ S i d e r i t e 1$ Textures The m a t e r i a l from number Two v e i n t h a t was s t u d i e d i s s t r o n g l y o x i d i z e d . Primary t e x t u r e s are o f t e n masked or o b l i t e r a t e d by t h i s a l t e r a t i o n and i t i s t h e r e f o r e d i f f i c u l t to g i v e an accurate d e s c r i p t i o n o f them that w i l l stand the t e s t of time as the v e i n i s e x p l o r e d f u r t h e r . Primary tex-t u r e s t h a t are seen are i d e n t i c a l to those of number One v e i n . F i g u r e 56. Van de Veer diagram to show paragenesis of primary and secondary minerals of number Two v e i n . 80. Secondary A l t e r a t i o n The secondary m i n e r a l s i n number Two v e i n are g i v e n i n o r d e r of abundance and wit h r e l a t i v e percentages i n the f o l l o w i n g t a b l e . S c o r o l i t e 50$ A n g l e s i t e 25$ Bindheimite 20$ G o e t h i t e 5$ Textures e x h i b i t e d by the secondary m i n e r a l s are the same as those d e s c r i b e d f o r number One v e i n . P aragenesis A Van de Veer diagram f o r number Two v e i n i s g i v e n i n f i g u r e 56. The diagram i s based on scant i n f o r m a t i o n and i s not as trust w o r t h y as that g i v e n f o r number One v e i n . Temperature of D e p o s i t i o n and C l a s s i f i c a t i o n The temperature of d e p o s i t i o n i s co n s i d e r e d to be s i m i l a r to t h a t of number One v e i n , but the r e l a t i v e predomin-ance of a r s e n o p y r i t e over m i n e r a l s s u g g e s t i v e of lower temper-ature i n d i c a t e s t h a t the temperature of d e p o s i t i o n was perhaps somewhat h i g h e r i n number Two v e i n than i t was i n number One v e i n . The a r s e n o p y r i t e geothermometer gave a temperature of d e p o s i t i o n f o r t h a t m i n e r a l below 350°C. Number Two v e i n i s c l a s s i f i e d as a mesothermal to" 81. hypothermal c a v i t y f i l l i n g type v e i n d e p o s i t . NUMBER THREE VEIN Number Three v e i n i s a long s t r u c t u r e , about which r e l a t i v e l y l i t t l e i s known. The v e i n i s made up of m i n e r a l -i z e d shoots t h a t are thought to be c o n t r o l l e d by, but not a l l along, one main, eastward t r e n d i n g zone of s h e a r i n g . The s t r u c t u r e has been f o l l o w e d on s u r f a c e f o r a t l e a s t t h i r t e e n thousand f e e t , but no underground work or d r i l l i n g has been done on i t . I t s t r i k e s about N80°E and d i p s northward a t an angle of about 50°• The shear zone c o n t a i n s s i l i c i f i e d gouge and f a u l t b r e c c i a t h a t i s s p a r i n g l y impregnated w i t h arseno-p y r i t e and p y r i t e . Lenses of s i d e r i t e c o n t a i n i n g jamesonite and g a l e n a occur l o c a l l y , but these are g e n e r a l l y s t r o n g l y o x i d i z e d . Widths of the shear zone vary to almost one hundred f e e t , but widths of m i n e r a l i z e d l e n s e s are much s m a l l e r . Branching s t r u c t u r e s are thought to have l o c a l i z e d the m i n e r a l -i z a t i o n found c l o s e to the shear zone i n some cases. Primary m i n e r a l s i n number Three v e i n are l i s t e d below with t h e i r average estimated r e l a t i v e p r o p o r t i o n s . They make up l e s s than 10$ of the e n t i r e exposed v e i n . Galena 35$ Jamesonite 45$ S i d e r i t e 15$ P y r i t e 5$ F i g u r e 57« Discontinuous s t r i n g e r s of anhedral p y r i t e  g r a i n s (dark) i n galenaT" 1 - N i c o l . x 2 5 . 82 Textures M i n e r a l i z e d l e n s e s from number Three v e i n c o n t a i n very l i t t l e p y r i t e and a r s e n o p y r i t e . The only o t h e r primary m i n e r a l s t h a t have been i d e n t i f i e d i n m a t e r i a l from number Three v e i n are galena, jamesonite and s i d e r i t e . P y r i t e occuts i n t h i n , d i s c o n t i n u o u s s t r i n g e r s or l a y e r s of i n d i v i d u a l , subhedral, equant g r a i n s i n galena, jamesonite and s i d e r i t e . In s i d e r i t e , p y r i t e a l s o occurs as b l e b s or aggregates of anhedral g r a i n s . A r s e n o p y r i t e occurs s p a r i n g l y as anhedral g r a i n s i n s i d e r i t e , but not i n the other m i n e r a l s . Galena i n number Three v e i n i s i n masses of r e l a t i v e l y coarse g r a i n s i z e i n a gangue of s i d e r i t e . Such masses are made up of both ' s t r a i n e d ' and ' u n s t r a i n e d ' galena. ' S t r a i n e d ' galena i s e v i d e n t from the bent nature of the cleavage s u r f a c e s i n the m i n e r a l , while the ' u n s t r a i n e d ' v a r i e t y has f l a t cleavage s u r f a c e s . The two types of galena are intergrown i n an i r r -e g u l a r and a p p a r e n t l y random f a s h i o n t h a t may simply be due to the way the specimen was c u t . Galena from number Three v e i n c o n t a i n s As, Sb, Ag, Cu and Sn i n d e c r e a s i n g order of abundance t r a c e c o n s t i t u e n t s . Jamesonite occurs s e p a r a t e l y i n s i d e r i t e . Wo c o n t a c t s between jamesonite and galena were noted. Jamesonite i s i n Figure 58. Van de Veer diagram to show paragenesis of  primary and secondary minerals of number Three vein. NUM B E R T H R E E V E I N van de veer pa r a g e n e t i c d i a g r a m 83. blebs and masses of f i n e , matted, p r i s m a t i c g r a i n s . Sinuous ' v e i n l e t s ' of coarse g r a i n e d jamesonite, a l s o showing random arrangements of g r a i n s , t r a v e r s e such f i n e g r a i n e d mats. T h i s type of t e x t u r e i s s i m i l a r to t h a t found i n Rex v e i n . Jamesonite from the number Three v e i n has been assayed and c o n t a i n s as much as 66 oz. of s i l v e r per ton. The jamesonite has been c a r e f u l l y s t u d i e d f o r i n c l u d e d s i l v e r min-e r a l s , but none were noted. S i d e r i t e c u t s galena and jamesonite. Where s i d e r i t e c u t s g a l e n a i t s emplacement i s g e n e r a l l y c o n t r o l l e d by the cleavage of t h a t m i n e r a l . Wo such cleavage c o n t r o l of s i d e r i t e i s found i n the case of jamesonite. V e i n l e t s of s i d e r i t e o f t e n show a 'flow' t e x t u r e due to c o l o u r banding of carbonate. Where such banding occurs i t i s p a r a l l e l to the w a l l s of the v e i n l e t s i . e . the galena or jamesonite. - s i d e r i t e c o n t a c t s . Secondary A l t e r a t i o n E x t e n s i v e o x i d a t i o n of primary s u l p h i d e s and gangue of number Three v e i n has r e s u l t e d i n the f o r m a t i o n of g o e t h i t e , a n g l e s i t e , b i n d h e i m i t e and s c o r o d i t e . The a l t e r a t i o n i s s i m i l a r to t h a t d e s c r i b e d f o r number One v e i n . P aragenesis The paragenesis of number Three v e i n m a t e r i a l i s r a t h e r simple. A Van de Veer diagram to show the paragenetic sequence 84 i s i n c l u d e d i n f i g u r e 58... Since the m a t e r i a l a v a i l a b l e to date i s scant, t h i s paragenesis may be incomplete. The ' f l o w 1 t e x t u r e e x h i b i t e d by s i d e r i t e suggests t h a t perhaps c o l l o i d a l d e p o s i t i o n was i n v o l v e d d u r i n g t h i s stage. C o l l o i d a l t e x t u r e s are a l s o found i n Rex v e i n m a t e r i a l . The seemingly strange combination o f ' s t r a i n e d ' and •u n s t r a i n e d ' g a lena i n i n t i m a t e i n t e r g r o w t h s i n number Three v e i n as w e l l as the f r a c t u r e d nature of galena ( l a t e r f i l l e d by s i d e r i t e ) i n d i c a t e t h a t some movement on the number Three v e i n s t r u c t u r e has o c c u r r e d a f t e r d e p o s i t i o n of galena. The l a c k of b r e c c i a t i o n of jamesonite i n d i c a t e s t h a t t h i s m i n e r a l was dep-o s i t e d a f t e r t h i s movement had ceased. Temperature of D e p o s i t i o n and C l a s s i f i c a t i o n The r e l a t i v e predominance of m i n e r a l s l i k e g a l ena and jamesonite over p y r i t e i n number Three v e i n i n c o n t r a s t to the opposite r e l a t i o n s h i p i n number One and number Two v e i n s , suggests that m i n e r a l i z a t i o n was emplaced at lower temperatures i n number Three v e i n than i t was i n number One and number Two v e i n s . C o n d i t i o n s o f temperature and pressure cannot be b r a -cketed more c l o s e l y than has been done f o r number One v e i n and the temperature range g i v e n f o r number Three v e i n by g e o l o g i c thermometers i s s i m i l a r to that o f number One v e i n . The v e i n i s c l a s s i f i e d as an open f r a c t u r e f i l l i n g , v e i n d e p o s i t formed under mesothermal c o n d i t i o n s . 85. REX VEIN Ex t e n s i v e s u r f a c e s t r i p p i n g on Rex v e i n has exposed t h i s s t r u c t u r e f o r a l e n g t h of two thousand f e e t . The v e i n i s m i n e r a l i z e d a t the s u r f a c e over about h a l f of i t s l e n g t h . A l i m i t e d amount of d r i l l i n g has been done to t e s t the c o n t i n -u i t y of the s t r u c t u r e to a maximum depth of three hundred and f i f t y f e e t , and a program has r e c e n t l y been s t a r t e d to explore the v e i n underground. Rex v e i n i s l e s s sinuous than any of the v e i n s des-c r i b e d b e f o r e . The v e i n s t r i k e s N80°E and d i p s northward at about 55°» Movement on the v e i n f a u l t was l a r g e l y normal with a s m a l l d e x t r a l component. The amount of movement i s not known, but the u n m i n e r a l i z e d p a r t of the v e i n i s composed of f i n e c l a y e y gouge and on t h i s b a s i s i t i s thought that movement on the v e i n f a u l t was l a r g e r than on number One v e i n f a u l t where the f a u l t zone c o n t a i n s only angular b r e c c i a fragments. S l i c k e n s i d e s on the f a u l t w a l l s i n v a r i a b l y plunge to the east a t angles s t e e p e r than 80 . Post m i n e r a l i z a t i o n movement, i f i t o c c u r r e d , has been s l i g h t . The v e i n zone v a r i e s i n width from about twenty f e e t at the e a s t e r n end to f i v e f e e t a t the west end. The f o o t w a l l of the v e i n i s w e l l d e f i n e d , espec-i a l l y to the east, but the hanging w a l l i s not as prominent. The v e i n i s an i r r e g u l a r l y m i n e r a l i z e d zone of f a u l t gouge. M i n e r a l i z a t i o n tends to be c o n c e n t r a t e d near the 8 6 hanging w a l l at the west end of the v e i n and on the f o o t w a l l i n the e a s t e r n p a r t . M i n e r a l i z a t i o n i s massive where i t occurs and i s i n d i s c o n t i n u o u s , l e n t i c u l a r and branching pods t h a t are p a r a l l e l to the v e i n w a l l s and which are surrounded by f a u l t gouge. Pods of m i n e r a l i z a t i o n are c o n s i d e r e d to plunge s t e e p l y eastward i n the v e i n on the b a s i s of l i m i t e d d r i l l i n g i nforma-t i o n . Minor branching f a u l t s t h a t meet the main s t r u c t u r e are a p p a r e n t l y pre-ore and tend to concentrate m i n e r a l i z a t i o n near t h e i r i n t e r s e c t i o n w i t h the main s t r u c t u r e . Primary m i n e r a l s make up l e s s than one h a l f of the volume of Rex v e i n and are l i s t e d below w i t h t h e i r estimated average r e l a t i v e p r o p o r t i o n s . S i d e r i t e 35$ Jamesonite 25$ Dolomite 15$ Galena 7$ B o u l a n g e r i t e 5$ T e t r a h e d r i t e 5$ S p h a l e r i t e 5$ P y r i t e 3$ Textures Textures shown by the hydrothermal m i n e r a l s i n the Rex v e i n are more complex than are those e x h i b i t e d by these F i g u r e 59• G r a i n of s p h a l e r i t e surrounded by massive .jamesonite and e n c l o s i n g l a t h s of jamesonite 1 - N i c o l . x 25. F i g u r e 60. F r a c t u r e i n t e t r a h e d r i t e ( t ) f i l l e d by s i d e r i t e  ( s ) . T e t r a h e d r i t e encloses l a t h s of jamesonite. X - N i c o l s . x 75. 87 m i n e r a l s i n the o t h e r v e i n s . A r s e n o p y r i t e has not been noted i n the Rex v e i n , but p y r i t e occurs i n euhedral cubes, up to 5 mm. on the s i d e , i n dolomite, s i d e r i t e and much l e s s commonly i n galena and s p h a l -e r i t e . The other h a b i t of p y r i t e seen i n a s s o c i a t i o n s from number One v e i n i s not noted i n m a t e r i a l from Rex v e i n . S p h a l e r i t e occurs i n Rex v e i n i n two ways. The m i n e r a l i s found as an open space f i l l i n g on w a l l rock encrusted by galena and as equant, corroded g r a i n s or g r a i n aggregates i n dolomite, s i d e r i t e and l e s s commonly galena. Textures of t h i s nature suggest t h a t s p h a l e r i t e was formed e a r l y i n the parag-e n i t i c sequence. The m i n e r a l i s t y p i c a l l y dark r e d d i s h brown i n c o l o u r i n the handspecimen. Two X-ray powder photographs of s p h a l e r i t e from Rex v e i n gave c e l l edges of 5.44(0)$ and 5.42(6)$. (Det-ermined from the (002) and (004) r e f l e c t i o n s ) I f the v a r i a t i o n i n c e l l edge from a value of 5*409 f o r pure ZnS i s due e n t i r e l y to s u b s t i t u t i o n of i r o n f o r z i n c , a mole percentage of FeS i n excess of 40$ i s i n d i c a t e d . T h i s seems e n t i r e l y u n l i k e l y on the b a s i s of the c o l o u r of the m i n e r a l and from s p e c t r o g r a p h i c a n a l y s e s . About 6$ FeS.-is estimated from these two sources and i t i s suggested t h a t the remainder of v a r i a t i o n i n c e l l edge of s p h a l e r i t e i s due to s u b s t i t u t i o n of cadmium and manganese f o r z i n c . I t i s estimated from data by Skinner (1961) that l e s s F i g u r e 61. Jamesonite (.j) and t e t r a h e d r i t e ( t ) i n c o n t a c t . Note v e i n l e t of .jamesonite i n t e t r a h e d r i t e .  X - N i c o l s . x 2 5 . F i g u r e 62. Jamesonite l a t h s ( j ) enclosed by s i d e r i t e (s) showing t r i a n g u l a r cleavage p i t s .  1 - N i c o l . x 7 5 . 88. than two mole pe r c e n t CdS would account f o r the remainder of the v a r i a t i o n i n c e l l edge of s p h a l e r i t e from i t s normal v a l u e . A s p e c t r o g r a p h i c a n a l y s i s of Rex v e i n s p h a l e r i t e shows the f o l l o w i n g minor c o n s t i t u e n t s i n d e c r e a s i n g order of abun-dance: Cd, Sb, Ag, Cu, Mn, Pb, Sn. T e t r a h e d r i t e occurs i n l a r g e , roughly equant g r a i n s with corroded boundaries i n s i d e r i t e and jamesonite. The m i n e r a l i s c u t by s t r a i g h t , narrow f r a c t u r e s t h at are f i l l e d with dolomite and which are l i n e d w i t h supergene c o v e l l i t e . T e t r a -h e d r i t e o f t e n c o n t a i n s s m a l l , equant, randomly o r i e n t e d blebs of c h a l c o p y r i t e , which i s thought to have exsolved from i t . Prom the corroded nature of t e t r a l i e d r i t e i t seems f a i r l y c e r t a i n t h a t t h i s m i n e r a l formed r e l a t i v e l y e a r l y i n the h i s t o r y of the v e i n ^ The l a c k of t e x t u r a l r e l a t i o n s h i p s between t e t r a h e d r i t e and s p h a l e r i t e makes i t d i f f i c u l t to say which of these two m i n e r a l s was d e p o s i t e d f i r s t . Grains of t e t r a h e d r i t e are commonly a c e n t -imeter or more a c r o s s . An X-ray powder photograph of Rex v e i n t e t r a h e d r i t e gave a c e l l edge of 1 0 . 5 7 ( 6 ) $ and the presence of Sb, Cu, Ag, Pb and Pe w i t h t r a c e s of Sn, Zn, Cd, As, Au, i n d e c r e a s i n g order of abundance, i s i n d i c a t e d i n a s p e c t r o g r a p h i c a n a l y s i s . Galena occurs as e n c r u s t a t i o n s of s p h a l e r i t e and i s i n t u r n e n c r u s t e d by dolomite (which o f t e n encloses b o u l a n g e r i t e needles) and the whole a s s o c i a t i o n i s cut by s i d e r i t e . A few F i g u r e 63. Pine g r a i n e d .jamesonite ( j ) 'cut' by a s t r i n g e r  of coarse g r a i n e d jamesonite (j)» Note the  1 t r a c h y t o i d 1 l i k e t e x t u r e and i n c i p i e n t a l t e r a - t i o n along cracks not c o n t r o l l e d by cleavage  of jamesonite.  X - M c o l s . x 25 . F i g u r e 64. Jamesonite ( j ) and galena (g) i n c o n t a c t ,  showing the apparent replacement of galena  by jamesonite t h a t i s i n no way c o n t r o l l e d  by the cleavage of galena. 1 - N i c o l . x 25. 89 p y r i t e cubes were observed e n t i r e l y surrounded by galena. Galena i s g e n e r a l l y coarse g r a i n e d and u n s t r a i n e d , although a few specimens of g a l e n a w i t h s l i g h t l y bent cleavage planes can be found. T e x t u r a l r e l a t i o n s h i p s between galena and jamesonite suggest t h a t jamesonite i s l a t e r than galena since i t has i n v a -ded and corroded t h a t m i n e r a l . Galena from Rex v e i n c o n t a i n s t r a c e s of Sb, Ag, Zn, Cu, Sn i n d e c r e a s i n g order of abundance. Jamesonite i n c o n t a c t w i t h galena and t e t r a h e d r i t e has a l r e a d y been mentioned. T h i s m i n e r a l occurs i n massive, i n t e r -grown aggregates o f t h i c k , p r i s m a t i c g r a i n s , commonly l e s s than .1 mm. l o n g ( f i n e r g r a i n e d than i n number One and number Two v e i n s ) . Jamesonite prisms are commonly a l i g n e d , g i v i n g a banded or ' t r a c h y t o i d ' t e x t u r e . In many specimens narrow bands of s l i g h t l y c o a r s e r g r a i n e d jamesonite 'cut' t h i s f i n e r g r a i n e d banded jamesonite. Such narrow bands are g e n e r a l l y p a r a l l e l to the banding of the f i n e g r a i n e d jamesonite. Jamesonite i s u s u a l l y surrounded by dolomite and where these two m i n e r a l s are seen i n c o n t a c t a c o n s i d e r a b l e amount of d i s r u p t i o n of the jamesonite i s evident." I n d i v i d u a l prisms of jamesonite i n such cases are g e n e r a l l y removed s l i g h t l y from the jamesonite agg-regate and are surrounded by dolomite. E x t e n s i v e i n v a s i o n by dolomite of jamesonite i s a l s o e v ident i n such cases. Where jamesonite i s i n c o n t a c t with t e t r a h e d r i t e and galena, prisms of jamesonite o f t e n protrude i n t o these m i n e r a l s from the main F i g u r e 65. Galena (g) i n c o n t a c t with, dolomite ( d ) . The a c i c u l a r c r y s t a l s of b o u l a n g e r i t e (b)  are a l i g n e d s u b p a r a l l e l to the g a l e n a - dolomite c o n t a c t . This type of t e x t u r e i s  suggestive of c o l l o i d a l d e p o s i t i o n of t h i s m a t e r i a l . 1 - N i c o l . x 66. F i g u r e 66. S i d e r i t e (s) f i l l i n g f r a c t u r e s i n t e t r a h e d r i t e  ( t ) . G o v e l l i t e (c) l i n e s the f r a c t u r e s . 1 - N i c o l . x 100. 9 0 mass of jamesonite. S i d e r i t e occurs i n c o a r s e l y c r y s t a l i n e aggregates t h a t e x h i b i t e x c e l l e n t (rhomboxedral) cleavage. The m i n e r a l i s commonly l i g h t brown i n c o l o u r and weathers dark brown and b l a c k . An X-ray powder p a t t e r n of Rex s i d e r i t e i n d i c a t e s that t h i s m i n e r a l i s manganiferous. A s p e c t r o g r a p h i c a n a l y s i s i n d i -c a t e s the presence of Mn, Mg, and Ca i n d e c r e a s i n g order of abundance. Dolomite d i f f e r s from s i d e r i t e only i n c o l o u r . D o l -omite has a grey c o l o u r , i t was i d e n t i f i e d from i t s X-ray powder p a t t e r n . The m i n e r a l o f t e n c o n t a i n s disseminated needles of b o u l a n g e r i t e . The carbonate stage of hydrothermal a c t i v i t y i s con-s i d e r e d to have s t a r t e d w i t h the i n t r o d u c t i o n of dolomite a t about the same time as, or s l i g h t l y a f t e r , the i n t r o d u c t i o n of jamesonite. That these two m i n e r a l s must have been more or l e s s contemporaneous i s c o n s i d e r e d l i k e l y on the b a s i s of the flow t e x t u r e of jamesonite and on the b a s i s of the r e l a t i o n s between jamesonite and dolomite. The presence i n the v e i n of b r e c c i a t e d dolomite c o n t a i n i n g b o u l a n g e r i t e ( i d e n t i f i e d by i t s X-ray powder p a t t e r n ) and s p h a l e r i t e with f r a c t u r e s f i l l e d by b a r r e n s i d e r i t e i s c o n s i d e r e d as evidence f o r a weak stage of movement on the v e i n d u r i n g the l a t e p e r i o d of hydrothermal a c t i v i t y and subse-quent i n t r o d u c t i o n of s i d e r i t e . The presence of t h i s b r e c c i a F i g u r e 67» A l t e r a t i o n of massive aggregates of f i n e g r a i n e d  .jamesonite (.j) along f r a c t u r e s u n r e l a t e d to  cleavage of jamesonite. The a l t e r a t i o n of  jamesonite i s a y e l l o w mixture of bindheimite  and a n g l e s i t e ( b ) . The f u z z y r i m of the f r a c t u r e s  r e p r e s e n t s p a r t l y a l t e r e d jamesonite.  1 - N i c o l . x 25» 91. t e x t u r e i n some cases and i t s absence i n o t h e r s i s c o n s i d e r e d to i n d i c a t e that the carbonate stage of m i n e r a l i z a t i o n was an e s s e n t i a l l y continuous process t h a t was not markedly i n t e r r u p t e d by the weak b r e c c i a t i o n of some dolomite a f t e r i t had been de-p o s i t e d . Secondary A l t e r a t i o n Rex v e i n m a t e r i a l p r o v i d e s a good example f o r study of secondary a l t e r a t i o n . The secondary m i n e r a l s and t h e i r estimated r e l a t i v e p r o p o r t i o n s i n the v e i n are l i s t e d below. Goe t h i t e 5 4 $ Bindheimite 40$ A n g l e s i t e 5$ C o v e l l i t e 1$ Textures shown by these secondary m i n e r a l s are d e s c r i b e d below. Goe t h i t e occurs as brown, f i n e g r a i n e d , amorphous masses and as boxworks a f t e r s i d e r i t e . Bindheimite occurs admixed with l e s s e r a n g l e s i t e i n canary y e l l o w masses and f i n e g r a i n e d aggregates, and was i d e n -t i f i e d by i t s X-ray powder p a t t e r n . A s p e c t r o g r a p h i c a n a l y s i s of a mixture of b i n d h e i m i t e and a n g l e s i t e showed the presence of Sb, Pb, Pe, Ag, Cu with t r a c e s of Sn and A l i n d e c r e a s i n g order of abundance. I t i s c o n s i d e r e d t h a t i r o n may be due to admixed g o e t h i t e . The presence of s i l v e r suggests t h a t some of 92:. the m a t e r i a l may be s t e t e f e l d i t e Ag 2Sb206 (0, OH). The powder p a t t e r n s of s t e t e f e l d i t e and bindheimite are very much a l i k e , s i n c e these two m i n e r a l s are i s o s t r u c t u r a l and the two can only be separated with d e t a i l e d work. In any case secondary s i l v e r v a l u e s are a p p a r e n t l y a s s o c i a t e d with t h i s canary y e l l o w mixture t h a t i s l a r g e l y made up of a n g l e s i t e and b i n d h e i m i t e . J a r o s i t e s were not noted i n any of the secondary a s s o c i a t i o n s from Rex v e i n . Bindheimite i s c l o s e l y a s s o c i a t e d with jamesonite and has r e p l a c e d t h a t m i n e r a l along f r a c t u r e s . The cleavage c o n t r o l of a l t e r a t i o n of jamesonite, so common i n number One and number Two v e i n s because jamesonite there i s coarse g r a i n e d , i s not e v i d e n t i n Rex m i n e r a l i z a t i o n , s i n c e jamesonite i s so f i n e g r a i n e d . A l t e r a t i o n of jamesonite appears to have been r a t h e r random and c o n t r o l l e d by f r a c t u r e s i n massive, f i n e g r a i n e d jamesonite. A n g l e s i t e occurs as t h i n , grey c o a t i n g s on galena that show c o l l o f o r m banding. The m i n e r a l i s a l s o present i n smal pro-p o r t i o n s w i t h b i n d h e i m i t e . C o v e l l i t e l i n e s dolomite f i l l e d v e i n l e t s i n t e t r a h e d r i t e . P a r a g e n e s i s Prom the f o r e g o i n g t e x t u r a l d e s c r i p t i o n s the paragenesis F i g u r e 68> Van de Veer diagram to show paragenesis of  primary and secondary m i n e r a l s i n Rex v e i n . R E X V E I N van de veer paragenetic diagram anglesite 93 of the primary arid secondary m i n e r a l s i s c l e a r . A Van de Veer diagram showing the para g e n e t i c sequence i s g i v e n i n f i g u r e 68. T h i s diagram shows not only the paragenesis, but a l s o the r e -l a t i v e abundance of the m i n e r a l s and the r e l a t i v e p r o p o r t i o n s of replacement and v e i n i n g t e x t u r e s shown by them. The 'flow' t e x t u r e s e x h i b i t e d by jamesonite and by b o u l a n g e r i t e i n dolomite suggests that these m i n e r a l s were de-p o s i t e d from c o l l o i d a l s o l u t i o n s . C r u s t i f i c a t i o n of s p h a l e r i t e on w a l l rock and of galena on s p h a l e r i t e , w i t h mammillary and r e n i f o r m banding seems to support such a mode of d e p o s i t i o n f o r these m i n e r a l s a l s o . A s u g g e s t i o n t h a t such c o l l o i d a l d e p o s i -t i o n may a l s o have occ u r r e d i n number Three v e i n i s borne out by the banding of s i d e r i t e from t h a t v e i n . Temperature of D e p o s i t i o n and C l a s s i f i c a t i o n The temperature of d e p o s i t i o n of hydrothermal m i n e r a l s cannot be e s t a b l i s h e d more c l o s e l y than has been done f o r the number One, Two and Three v e i n s . The same s e t of maximum temp-e r a t u r e s quoted f o r these d e p o s i t s h o l d a l s o f o r Rex v e i n . In a d d i t i o n , however, the e x s o l u t i o n of c h a l c o p y r i t e from t e t r a -h e d r i t e g i v e s a temperature f o r t h i s stage as being l e s s than 5 0 0°C. ( T h i s v a l u e i s q u e s t i o n a b l e , as d i f f e r e n t temperatures are g i v e n by v a r i o u s workers f o r t h i s e x s o l u t i o n p o i n t . ) The assemblage of m i n e r a l s i n Rex v e i n i s suggestive 94 of lower temperatures of d e p o s i t i o n than those of the previously-d e s c r i b e d v e i n s . I t i s c h a r a c t e r i s t i c of mesothermal v e i n type d e p o s i t s and t h i s g i v e s the v e i n a rough range of temperature of d e p o s i t i o n between 500°C and 250°C. Zoning;'of the D e p o s i t s There i s no evidence t h a t marked zoning of m i n e r a l -i z a t i o n e x i s t s i n the v e i n s d e s c r i b e d . Some evidence f o r zoning i n the number One, Two, and Three v e i n system e x i s t s i n the form of r e l a t i v e p r o p o r t i o n s of hydrothermal m i n e r a l s . A glance at the Van de Veer diagrams f o r these three v e i n s r e v e a l s the pro-g r e s s i v e decrease i n p r o p o r t i o n of p y r i t e and a r s e n o p y r i t e i n the d e p o s i t s westward and the concomitant i n c r e a s e i n p r o p o r t i o n s of jamesonite and galena. New i n f o r m a t i o n w i l l have to be obtained from under-ground work, before anything c o n c r e t e c o n c e r n i n g both zoning i n the camp and i n d i v i d u a l v e i n s can be e s t a b l i s h e d . Time of Emplacement of V e i n M i n e r a l s I t i s not d i f f i c u l t to give a range of time f o r the p e r i o d of hydrothermal a c t i v i t y , but i t i s not p o s s i b l e to put a s p e c i f i c time on t h i s stage. 95 The v e i n s c o n t a i n fragments of b r e c c i a t e d w a l l rock. T h i s w a l l rock has not been a f f e c t e d by hydrothermal a c t i v i t y and the Phase I l i n e a t i o n on these fragments of w a l l rock have been pr e s e r v e d . T h i s means t h a t the v e i n f a u l t s must have formed a f t e r Phase I f o l d i n g . The second phase l i n e a t i o n was not noted on b r e c c i a fragments, except i n number One v e i n . I t i s probable t h a t a l l the v e i n s were formed l a t e r than Phase I I f o l d i n g . I t seems l i k e l y t h a t the v e i n f a u l t s were formed before or d u r i n g the p e r i o d when i n t r u s i o n of g r a n i t i c rocks o c c u r r e d and i t i s l i k e l y , but not c e r t a i n , that hydrothermal a c t i v i t y was r e l a t e d to the g r a n i t i c rocks and t h a t v e i n m i n e r a l s were emplaced s h o r t l y a f t e r i n t r u s i o n . I t i s f a i r l y c e r t a i n t h a t the v e i n f a u l t s were formed p r i o r to the r e g i o n a l f a u l t s t h a t trend n o r t h south along Haggart and S e c r e t Creeks. Rex f a u l t i s o f f s e t by S e c r e t Creek f a u l t • I t i s not c e r t a i n t h a t m i n e r a l i z a t i o n of Rex f a u l t o c c u r r e d s i m i l t a n e o u s l y w i t h m i n e r a l i z a t i o n of number One, Two and Three v e i n f a u l t s , s i n c e the mineralogy of these two systems i s s l i g h t l y d i f f e r e n t . On the b a s i s of s i m i l a r mineralogy the number One, Two and Three v e i n s are thought to have been miner-a l i z e d contemporaneously. Although m i n e r a l i z a t i o n of Rex v e i n 96 i s d i f f e r e n t from t h a t of number One, Two and Three v e i n s , no evidence to suggest t h a t Rex v e i n was not m i n e r a l i z e d contem-poraneously w i t h them i s found. In s h o r t , t h e r e f o r e , the v e i n s were m i n e r a l i z e d a t the same time, s h o r t l y a f t e r igneous i n t r u s i o n and v e i n f a u l t s were formed at or before the time of i n t r u s i o n of g r a n o d i o r i t i c rocks and may even have been formed due to t h i s i n t r u s i o n . SUMMARY OP GEOLOGIC HISTORY The c o n c l u s i o n s drawn from t h i s study can best be presented i n the form of a g e o l o g i c h i s t o r y , which i s s e t out below i n c h r o n o l o g i c a l order. The g e o l o g i c h i s t o r y here pre-sented g i v e s only r e l a t i v e times as absolute times are not a v a i l a b l e . 1 . D e p o s i t i o n of a sequence of impure sandstones and s i l t s t o n e s w i t h i n t e r b e d d e d a r g i l l a c e o u s r o c k s . The order of d e p o s i t i o n has not been worked out s i n c e s t r a t i g r a p h i c tops were not found i n the area. The g e n e r a l s t r u c t u r a l sequence from top to bottom i s : 1 . Massive grey q u a r t z i t e , with b l a c k p h y l l i t e and minor in t e r b e d d e d b l a c k l i m e s t o n e . 2 . Micaceous q u a r t z i t e w i t h interbedded grey p h y l l i t e . 3. Micaceous q u a r t z i t e w i t h interbedded p h y l l i t e , l i m e -stone and greenstone. 97 The lower u n i t i s c o n s i d e r e d to be a p o s s i b l e c o r r e l a t i v e of the Upper S c h i s t on Keno and Galena H i l l s . 2. I s o c l i n a l f o l d i n g or s h e a r i n g to produce bedding plane f o l i a t i o n accompanied by r e g i o n a l metamorphism. H i g h e s t grade of r e g i o n a l metamorphism reached i s g r e e n s c h i s t f a c i e s . 3. Phase I, s u b i s o c l i n a l f o l d i n g of the f o l i a t i o n w i t h , predominant n o r t h up and over south sense on eastward p l u n g i n g axes. Phase I f o l d i n g may be a l a t e e f f e c t of the s h e a r i n g or i s o c l i n a l f o l d i n g t h a t produced the f o l i a t i o n . Phase I f o l d i n g i s c o n s i d e r e d to have produced the east west t r e n d i n g , sub-i s o c l i n a l f o l d s on Keno and Galena H i l l s . Phase I f o l d i n g was probably accompanied by some r e g i o n a l metamorphism. 4. Phase I I f o l d i n g of the f o l i a t i o n on northwestward p l u n g i n g axes. Phase I I was e s s e n t i a l l y a b r i t t l e deformation that has had only minor e f f e c t i n the area i n q u e s t i o n . Phase I I was weaker than Phase I . E f f e c t s of Phase I I are more marked south of the map a r e a i n d i c a t i n g that the c e n t r e of s t r o n g e s t Phase I I s t r e s s was south of the map a r ea. 5. F a u l t i n g i n an east west d i r e c t i o n to produce v e i n f a u l t s i n c l u d i n g the Rex f a u l t and perhaps a l s o the B l a ck P h y l l i t e - T i n H i l l f a u l t . T h i s f a u l t i n g may be due to i n t r u s i o n of quartz d i o r i t i c r o c k s . 6. I n t r u s i o n of quartz d i o r i t i c rocks and r e l a t e d types, p o s s i b l y i n c l u d i n g a u g i t i t e ?. The shape of the i n t r u d e d mass i s s i l l l i k e i n the west and becomes p r o g r e s s i v e l y more t r a n s -98. g r e s s i v e and t h i c k e r (stock l i k e ) i n the e a s t . Motion of the magma d u r i n g i n t r u s i o n i s thought to have been from west to e a s t . The magma i s thought to have been a c r y s t a l mush (about Zyfo s o l i d ) d u r i n g i n t r u s i o n and i s thought to have been i n t r u d e d f o r p a r t of i t s l e n g t h along a f a u l t . The temperature o f the i n t r u d i n g mass i s p l a c e d at about 600°C and the depth below the sur f a c e o f g r a n o d i o r i t i c rocks a t the time o f i n t r u s i o n i s thought to have been about twelve k i l o m e t r e s o r l e s s . I n t r u s i o n o f quartz f e l d s p a r porphyry dykes i s thought to have accompanied o r f o l l o w e d s h o r t l y a f t e r i n t r u s i o n o f quartz d i o r i t i c r o c k s . 7. Thermal metamorphism of the r e g i o n a l l y metamorphozed sedimentary rocks surrounding the quartz d i o r i t e s tock. No thermal metamorphic e f f e c t s were detected around the s i l l to the west. Thermal metamorphism f o l l o w e d i n t r u s i o n c l o s e l y . The h i g h e s t grade o f thermal metamorphism approaches pyroxene h o r n f e l s f a c i e s , but the h i g h e s t s t a b l e f a c i e s i s hornblende h o r n f e l s f a c i e s . Corundum has developed metastably near the igneous c o n t a c t . The t h i c k n e s s o f the zone of rocks a f f e c t e d by thermal metamorphism i s thought to be l e s s than one thou-sand f e e t . Low grade thermal metamorphic assemblages pass imperceptably i n t o surrounding r e g i o n a l metamorphic assemblages. 8. Metasomatism accompanied thermal metamorphism or fo l l o w e d i t c l o s e l y . I t s e f f e c t s are very minor and c o n s i s t 99 l a r g e l y of f o r m a t i o n of micas from a n d a l u s i t e and corundum. The f o r m a t i o n of micas from these m i n e r a l s i s thought to be by r e t r o g r e s s i v e metamorphism i n i t i a t e d by potash metasomatism. Some tourmaline i s thought to be of metasomatic o r i g i n . 9. Hydrothermal m i n e r a l i z a t i o n of v e i n f a u l t s . A s i d e from the a r s e n o p y r i t e - j a m e s o n i t e - s i d e r i t e a s s o c i a t i o n s of number One, Two and Three v e i n s and s i d e r i t e - j a m e s o n i t e -g a l e n a - t e t r a h e d r i t e combinations of Rex v e i n , which are argen-t i f e r o u s and which are d e s c r i b e d i n t h i s d i s c u s s i o n , s e v e r a l o t h e r types of m i n e r a l i z a t i o n occur. Gold b e a r i n g a r s e n o p y r i t e v e i n s are found c l o s e to the quartz d i o r i t i c stock. There i s evidence i n the p l a c e r d e p o s i t s t h a t q u a r t z - g o l d v e i n s were o r i g i n a l l y a s s o c i a t e d with t h i s m i n e r a l i z a t i o n , but i t i s c o n s i d e r e d t h a t these were formed near the s u r f a c e a t the time of i n t r u s i o n of quartz d i o r i t i c rocks and that they are now weathered away. Other m i n e r a l i z a t i o n i n the map a r e a i n c l u d e s s c h e e l i t e i n v e i n and skarn d e p o s i t s and as d i s s e m i n a t i o n s i n quartz d i o r i t e . C a s s i t e r i t e m i n e r a l i z a t i o n a s s o c i a t e d with tourmaline occurs on T i n H i l l . 10. G l a c i a t i o n d u r i n g the p l e i s t o c e n e . Evidence f o r two g l a c i a l p e r i o d s i s found w i t h i n the map area. BIBLIOGRAPHY Aho, A.E. (19^9) , "Mineralogy of some heavy sands of the McQuesten R i v e r Area, Y.T.", B.A.Sc. Thesis,U.B.C. unpublished. Aho, A.E. (1963) " S i l v e r i n Yukon", B u l l . C.I.M.M., v o l . 5 6 , A p r i l , 1963. Aho, A.E. (1963) , S e l e c t e d r e p o r t s on Peso S i l v e r Mines L i m i t e d Anderson, E.M. (1948),"On l i n e a t i o n and p e t r o f a b r i c s t r u c t u r e and shearing by which they are produced',' J.G.S., v o l . 104. Armour-Brown, A. (1963) , "Zoning i n the m i n e r a l i z e d veins i n Secret Creek-Dublin Gulch Area", Geology 409 Report, U.B.C. unpublished. Bostock, H.S. (1943) , "Upper McQuesten R i v e r , Yukon Terr-i t o r y " , G.S.C. P r e l . Map 43-9. Bostock, H.S., (1947) , "Mayo, Yukon Territory',' G.S.C. map 89OAL. Bostock, H.S., (1948), "McQuesten, Yukon T e r r i t o r y " , G.S.C. P r e l . Map 48 - 25 . Bostock, H.S., (1948), " S t r u c t u r a l Geology of Canadian Ore Deposits", C.I.M.M. p.110-112. Boyle, R.W., (1957) , "The Geology and Geochemistry #of the Si l v e r - L e a d - Z i n c deposits of Galena H i l l , Yukon T e r r i -t o r y " , G.S.C. paper 57-1. Cairnes, D.D.,(1915)» "Mayo D i s t r i c t " , G.S.C.Mem.284, p . 3 8 1 . C a i r n e s , D . D . , ( l 9 l 6 ) , "Mayo D i s t r i c t " , G.S.C.Mem.284, p.427. C l a r k , L.A., ( i960) , "The Pe-As-S system: Phase r e l a t i o n s and a p p l i c a t i o n s " , Ec.Geol., vol . 55> No.7. Cloos, E . , ( 1 9 4 6 ) , "Lineation-A c r i t i c a l review", G.S.A.Mem.18. Coates, J.A., ( i960) , "Mineralographic Report on a prospect near Secret Creek, Mayo, Y.T.", Geology 409 Report, U.B.C, unpublished. C o c k f i e l d , W.E., (1918), "Mayo, Yukon T e r r i t o r y " , G.S.C.Mem. 284, f . 4 6 l . G a b r i e l s e , H. & Wheeler, J.O., (I960), " T e c t o n i c framework of Southern Yukon and North Western B.C.", G.S.C. paper 60-24. Green, L.H., (1956), "Mayo Lake, Y.T.", G.S.C. map 5-1956. Green, L.H. & McTaggart, K.C., ( i 9 6 0 ) , " S t r u c t u r a l s t u d i e s i n the Mayo D i s t r i c t , Y.T.", Proc.Geol.Assoc.Can., v 12, p.119-134. Green, L.H. & Roddick, J.A., (1962), "Dawson, Larson and Nash Creek map a r e a s , Y.T.", G.S.C. paper 62-7. Hess, H.H., (1949)» "Chemical composition and o p t i c a l prop-e r t i e s o f common c l i n o p y r o x e n e s " , Am.Min., v 34» p.621. Ingerson, E a r l , (1955), "Geologic Thermometry", Ann.Vol.Ec. Geol., p.341-411. K i n d l e , E.D., (1955), " P r e l i m i n a r y map, Keno H i l l , Y.T.", G.S.C. 55-12. L i t t l e , H.W., (1959), "Tungsten Deposits of Canada", p.21-29, P.34-36, G.S.C. Ec.Geol.Ser.17. McLean, T.A., (1914), "Lode mining i n Yukon", Mines Branch, Dept. Mines, Canada, p.127-159. McTaggart, K.C., (I960), "The Geology of Keno and Galena H i l l s , Y.T.", G.S.C. B u l l . 58. Read, P.B., (1957), "The P e t r o l o g y of the Greenstones of Keno H i l l " , B.A.Sc. T h e s i s , U.B.C. unpu b l i s h e d . Skin n e r , B.J., (1961), " U n i t C e l l Edges of S y n t h e t i c and N a t u r a l S p h a l e r i t e s " , Am.Min., v 46. Slemmons, D.B., (1962), "Determination of V o l c a n i c and P l u t o n i c P l a g i o c l a s e s u s i n g a 3 or 4 a x i s U n i v e r s a l Stage", G.S.A. spec, paper 69. Tempelman-Kluit, D.J., (1962), " M i n e r a l o g i c a l Report on a s u i t e of specimens from the Peso S i l v e r p r o p e r t y near Haggart Creek, Y.T.", Geology 409 r e p o r t , U.B.C. un p u b l i s h e d . Tempelman-Kluit, D.J., (1962), "Economic Geology o f S e c r e t Creek, Haggart Creek, D u b l i n Gulch ar e a " , P r i v a t e r e p o r t f o r Peso S i l v e r Mines L t d . Tempelman-Kluit, D.J., (1963), " M i n e r a l o g i c a l examination of a J i g concentrate from the P l a c e r a t D u b l i n Gulch, Y.T.", Geology 523 Report, U.B.C. unpublished. Tempelman-Kluit, D.J., (1963), "Geology of Shanghai, Argent, L a y s i e r and S e a t t l e Greek areas", Reports f o r S i l v e r T i t a n Mines u n p u b l i s h e d . Thompson, R.M., ( 1 9 4 5 ) . "An occurrence o f C a s s i t e r i t e a t D u b l i n Gulch, Y.T.", Ec.Geol.., v XL, no.2, p.142-147. Turner, E . J . , (1948), " E v o l u t i o n of metamorphic r o c k s " , G.S.A.Mem. 30. Wiser, E.H., (I960), " R e l a t i o n of Ore Dep o s i t s to Doming i n the North American C o r d i l l e r a " , G.S.A.Mem. 77. o Q -J <U D L E G E N D Camaara* aia*ai Par/l/n'.e M*,I**/*>**' MUrff Oaarrr aassat la.ttaat aar»at't M'ai.ra iiat.fa fa a.min* mimaa*i*\tii* A ain't* im wan •«*•/,*»««»* a-mariura - ••' i*rt arar- waaa ••' »*rmtmi •" « . - »• t'*r, -*»•"» lutr'n ra tmiaar aiaaa *a,ii>ta aaa liUmmhtmti Biata f*,Hllm « aaannra.aaa'ii "if it ait t mat t'ar aajiina t—taa' t" " r **airt,i»} Orar fSf/ma Imiaai aaarlt *>i ta i t a . t r / M'tataaaa aa a i > 11 'a . * • a~» I aai la ar'afa't •tlemtaaat a a a t t f a , taarH tiaia'ta amratalt (mlaai it . I ' I aarartltl Q . i . l , titan,aa fmtm Onifaa araa . , *> aft r > tfaa I a * r r ' a i a mai»af »/ arr-lata t <tr*a */ f l a a i , BI a aa alt tatatif tartaat Fatiari a* ~—~ J««mfiaf ' Ltaaa'laa -a* ttiae\'r fmit a • am VMM ' 1 . " "N. Ctaraar tiatiirai /OO B Saa t t ' I t a t ta-itiaa PESO SILVER MINES LTD (NPL) M a y o Y u k o n REGIONAL GEOt-OGY 4 S T R U C T U R A L T R E N D M A P HAGGART C R E E K - D U B L I N G U L C H A R E A , Y U K O N s a M w ~ ^ r c o n t o u r i n t e r v a l 5 0 0 feet M.N. L E G E N D G r a n o d i o r i t e M a s s i v e q u a r t z i t e 1 j M i c a c e o u s qua r t z i t e P h y l l i t e C a l c a r e o u s quartz ; + .<-Fault F o l i a t i o n t r e n d ( t e e t h in dip d i r e c t i o n ) L E G E N D G r a n o d i o r i t e M a s s i v e q u a r t z i t e Q u a r t z m i c a s c h i s t M i c a c e o u s q u a r t z i t e F e l d s p a t h i c q u a r t z i t e S h a l e e t c O © M i n e , p r o s p e c t o r s h o w i n g imm F a u l t — - C o n t a c t ***** A t t i t u d e of b e d d i n g f o l i a t i o n mm R i d g e — R o a d • S e t t l e m e n t L a k e - v r C r e e k o r R i v e r L im i t o f e x t e n s i v e t i l l c o v e r E L E V A T I O N S IN F E E T A B O V E M S . L G E O L O G Y G E N E R A L I Z E D P E S O S I L V E R M I N E S B L O C K D I A G R A M P O T A T O H I L L S - M O U N T H A L D A N E K E N O H I L L A R E A M a y o d i s t r i c t , Y u k o n D r a w n C o m p i l e d by D T K I n t e r p r e t e d M a r c h 1 9 6 4 

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