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UBC Theses and Dissertations

Contact relationships of Mount Carlyle Stock Slocan, British Columbia Childs, John Frazer 1968

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CONTACT RELATIONSHIPS OF MOUNT CARLYLE STOCK SLOCAN, BRITISH COLUMBIA by JOHN FRAZER CHILDS B . S c , Syracuse U n i v e r s i t y , 1965 A^  THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of Geology We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA SEPTEMBER, I96S In 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 o f the r e q u i r e m e n t s f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h C olumbia, I a g r e e t h a t 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-Study. I f u r t h e r a g r e e t h a t 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 o f t h i s t h e s i s f o r s c h o l a r l y p u rposes may be g r a n t e d by the Head o f 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 u n d e r s t o o d t h a t 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 h o t be a l l o w e d w i t h o u t my w r i t t e n - p e r m i s s i o n . Department of Geology The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada Date Sep tembe r27 , 1968 i ABSTRACT The deformed T r i a s s i c S l o c a n Group sedimentary r o c k s c o n -s i s t i n g o f a r g i l l i t e , l i m e s t o n e , and q u a r t z i t e , have been r e g i o n a l l y metamorphosed, f o l d e d , and i n t r u d e d and t h e r m a l l y metamorphosed by Nel son P l u t o n i c Rocks ( J u r a s s i c ) . M t . C a r l y l e s t o c k , a c o m p o s i t i o n a l l y zoned body 21 square m i l e s i n a e r i a l e x t e n t , was emplaced by f o r c e f u l i n t r u s i o n and p a s s i v e a s s i m i l a t i o n as d i s c e r n e d from the c o n t a c t e f f e c t s on the S l o c a n Group metasediments . The marg in o f the s tock i s enve loped i n a c o n t a c t meta-morphic a u r e o l e w i t h b i o t i t e , a n d a l u s i t e , garnet and s t a u r o -l i t e , c o r d i e r i t e , and s i l l i m a n i t e deve loped i n approximate i n c r e a s i n g o r d e r o f p r o x i m i t y t o the s t o c k m a r g i n . P e t r o g r a p h i c and s t r u c t u r a l ev idence i n a septum o f S l o c a n Group metasediments between M t . C a r l y l e s tock and the Ne l son B a t h o l i t h t o the south suggests t h a t the s t o c k p o s t d a t e s the b a t h o l i t h . E x p e r i m e n t a l da ta p e r t i n e n t t o the metamorphic m i n e r a l a s -semblages i n the c o n t a c t a u r e o l e o f M t . C a r l y l e s tock i n d i c a t e t h a t t empera tures up to a p p r o x i m a t e l y 650° c and p r e s s u r e s between 2\ and 7Kb. p r e v a i l e d d u r i n g c o n t a c t metaaorphism. The metamorphism i n the c o n t a c t r e g i o n s o f the s tock i s c h a r a c t e r -i s t i c o f f a c i e s s e r i e s i n t e r m e d i a t e between c o n t a c t and r e g i o n a l c o n d i t i o n s . i i : . -TABLE OF CONTENTS I . INTRODUCTION 1 A. GENERAL INTRODUCTION 1 a l Scope 1 b) Purpose 1 c) L 0 c a t i o n and Topography 2 d) Previous Work 2 e) Acknowledgements 4 B. GENERAL GEOLOGY 5 ¥)Slocan Group 5 b) Nelson P l u t o n i c Rocks 7 c) Mt. C a r l y l e Stock 9 I I . STRUCTURAL ELEMENTS IN THE CONTACT REGION IN MT. CARLYLE STOCK 13 A. PRIMARY STRUCTURES 13 B. SECONDARY STRUCTURES 16 a l Area I - 18 b) Area I I 24 c) Area I I I 28 d) Area IV 31 C. TEMPORAL RELATIONS BETWEEN THE NELSON  BATHOLITH AND MT. CARLYLE STOCK 39 D. MODE OF EMPLACEMENT"OF MT« CARLYLE STOCK 40 I I I . METAMORPHISM 42 A. SLOCAN GROUP SEDIMENTARY ROCKS 42 B. LIMESTONE-MARBLE ASSOCIATION 43 C. QUARTZITE 44 D. K-Ca RICH:'PELITE 46 E. MAGNESIAN PBLITE 48 F. FERROUS PELITE 52 G. SUMMARY OF MICROTEXTURAL INTERPRETATIONS 64 H. CONDITIONS OF METAMORPHISM 65 IV. CONCLUSIONS 71 V. REFERENCES CITED 75 i i i ILLUSTRATIONS Figure Page 1 Index Map f o r the F i e l d Area 3 2 Contact of Mt. C a r l y l e Stock i n Montezuma Creek 11 3 Zoned K-feldspar phenocrysts 11 4 Large t a l u s blocks of p o r p h y r i t i c quartz monzonite 11 5 B i o t i t i c i n c l u s i o n from M t . C a r l y l e stock 12 6 F o l i a t e d border phase of Mt . C a r l y l e stock 12 7 Crossbedding i n q u a r t z i t e from near southwest margin of M t . C a r l y l e stock 15 £ O r i g i n a l l a y e r i n g i n s c h i s t 15 9 O r i g i n a l l a y e r i n g i n p h y l l i t e 15 10 Map of M t . C a r l y l e stock and f o u r s t r u c t u r a l l y d i s t i n c t i v e areas i n the contact r e g i o n of the stock 17 11 Screens of s c h i s t intermixed w i t h g r a n i t i c rock of border of Mt. C a r l y l e stock 19 12 Screens of s c h i s t and gneiss at border of Mt. C a r l y l e stock 19 13 Screen of metasediment i n g r a n i t i c rock 19 14 T h i n l y laminated and f o l d e d metasediment i n and screens i n g r a n i t i c rock 22 15 16 Gneiss from margin of M t . C a r l y l e stock 22 17 Gneiss w i t h r i n g - l i k e c o n c e n t r a t i o n or b i o t i t e 23 1$ Pegmatite i n s c h i s t and gneiss 23 and 19 i v F igure Page 20 Large r o o f pendant i n M t . C a r l y l e stock 26 21 Roof pendant i n Mt. C a r l y l e stock 26 22 Tight f o l d i n g i n limestone roof pendant and i n Mt. "C a r l y l e stock 27 "23 24 S t r a i n - s l i p cleaVage c u t t i n g l a y e r i n g i n p h y l l i t e 30 25 I n t e n s e l y crumpled f o l i a t i o n i n p e l i t e 30 26 I n t e r s e c t i n g c r e n u l a t i o n s i n f o l i a t e d s c h i s t 30 27 F o l i a t e d metapelite c o n t a i n i n g a n d a l u s i t e and garnet porphyroblasts 33 2S F o l i a t i o n i n metapelite c o n t a i n i n g l a r g e a n d a l u s i t e porphyroblasts 33 29 O r i g i n a l l a y e r i n g s u b - p a r a l l e l t o f o l i a t i o n and i n p e l i t i c s c h i s t 33 30 31 Minor f o l d s i n interbedded p e l i t e and quartz-i t e beds 34 32 Minor f o l d s w i t h a small f a u l t t h a t has d i s -placed a f o l d limb 34 33 Blocks of p e l i t i c s c h i s t w i t h l a r g e a n d a l u s i t e porphyroblasts w i t h i n the f o l i a t i o n 34 34 C h i a s t o l i t e w i t h deformed cleavage and small r o d - l i k e i n c l u s i o n s of quartz 36 35 C h i a s t o l i t e w i t h a l i g n e d i n c l u s i o n s i n the c e n t r a l part of the c r y s t a l 36 36 C h i a s t o l i t e w i t h deformed l e n t i c u l a r quartz and i n c l u s i o n s 36 37 3# Thin bedded impure limestone 45 V Figure Page 39 F i b r o l i t e - b i o t i t e mats adjacent to a pegmatite vein i n t h i n l y interbedded quartzite and schist 45 40 F i b r o l i t e bundles with b i o t i t e and some museo-v i t e i n a quartz-feldspar groundmass 45 41 F i b r o l i t e with b i o t i t e rimming quartz and f e l d ! spar grains 42 C h i a s t o l i t e porphyroblasts i n random orientation within a f o l i a t i o n plane i n metapelite 47 43 C h i a s t o l i t e porphyroblasts with s e r i c i t e rims set i n a muscovite r i c h groundmass 47 44 Crenulation i n layered metapelite 47 45 S e r i c i t i z e d andalusite porphyroblasts i n a mus-covite-quartz-opaque matrix 51 46 Cordierite knots i n sc h i s t appear as brown spots on a weathered surface 51 47 Cordierite porphyroblasts i l l u s t r a t i n g p o i k i l o -and b l a s t i c texture 51 4S 49 Table of occurrences of common boundaries between mineral phases i n the contact metamorphic aureole of Mt. Carlyle stock 53 50 Map of Mt. Carlyle stock and inferred isograds i n the contact metamorphic aureole 54 50b Mineral assemblages and possible mineral reac-tions i n p e l i t i c metasediment from the contact aureole of Mt. Carlyle stock 55 51 A'FM diagrams f o r contact metamorphic mineral assemblages i n the aureole of Mt.Carlyle stock 56 52 Subhedral s t a u r o l i t e porphyroblast and euhedral garnet porphyroblast i n a b i o t i t e f o l i a t i o n V I Figure Page 5 3 Two s t a u r o l i t e porphyroblasts r e t a i n i n g i n c l u s i o n t r a i n s 5# 5 4 Andalusite porphyroblast t h a t formed dur i n g three stages of growth 5# 5 5 C h i a s t o l i t e rimmed by muscovite, b i o t i t e , and s t a u r o l i t e 60 5 6 S t a u r o l i t e w i t h i n c l u s i o n t r a i n s at edge of c h i a s t o l i t e porphyroblast 6 0 5 7 Two s t a u r o l i t e porphyroblasts p e n e t r a t i n g a c h i a s t o l i t e c r y s t a l 60 5 8 S t a u r o l i t e , c h i a s t o l i t e , garnet and b i o t i t e w i t h common borders 62 5 9 Small c h i a s t o l i t e porphyroblasts w i t h b i o t i t e and muscovite 62 6 0 Large subhedral garnet porphyroblast w i t h opaque i n c l u s i o n s 62 6 1 P IT Q-T diagram w i t h s t a b i l i t y curves p e r t i n e n t 2 t o rocks i n the contact metamorphic aureole of Mt. C a r l y l e stock 68 PLATES P l a t e 1 1 I. INTRODUCTION A) GENERAL INTRODUCTION a) Scope of the Investigation The contact regions of Mt. Carlyle stock and the Northern edge of the Nelson Batholith were mapped at a scale of approximately one inche = 1000 feet. Mapping was carried out during a nine week period in the summer of 1967. Twohundred-fifty hand specimens were collected from the Slocan Group metasediments, Mt. Carlyle stock and associated dikes and plugs. Seventy thin sections were prepared and studied. Other laboratory study included X-ray diffraction identification of very fine-grained minerals. b) Purpose The emphasis of the study i s twofold: an examination of the contact relationships of the stock and the surrounding rocks with attention given to possible modes of emplacement of the stock; and an investigation of the structural and mineralogical effects of the stock upon the enclosing sedi-mentary rocks. An attempt is made to determine the sequence of emplacement of the stock and the batholith to the south. 2 c) Location and Topography : Mt. Carlyle stock, in the northern half of the Slocan Map sheet, underlies a 21 square mile area between Slocan Lake on the West and Kootenay Lake on the East (see Fig.1), and i s centered on Mt. Carlyle (8688 feet) in the Selkirk Range. The area i s cut by a number of U-shaped, steep-walled val-leys which head in talus covered cirques as shown in Figure 2. Outcrop in the main streams i s extremely scarce and the best exposures were found in tributary channels. Ridges are sparse-ly vegetated above an elevation of 7000 feet and these provide good outcrop. Unfortunately the contact between ' Mt. Carlyle stock and the metasediments follows the major stream valleys in many areas, affording scant outcrop control. Access to the area i s provided by the road to the Utica Mine on the north, the Kaslo-New Denver road on the northeast, the road to the old mine towns of Cody and Sandon on the west, and the Southfork (Keen Creek) road on the east. Two t r a i l s lead into the area to old silver mines within Mt.Carlyle stock, one from Cody, the other from the Keen Creek road. d) Previous Work Cairnes (1934) studied the Slocan Mining Camp. He cl a s s i -fied the contacts of the Nelson Plutonic Rocks as gradational to intrusive in nature and described roof pendants and the surrounding Slocan Group. Sinclair and Libby (1967) studied 4 the mineral distribution in Mt.Carlyle stock using trend surface analysis. Irwin (1951) described the folding in the Howson Creek Basin west of the present area of study. Hedley (1952) des-cribed the Sandon area and defined a large recumbent structure which he termed the Slocan fold. Hyndman (1968) delineated three stages of folding in the Shuswap metamorphic complex and the Slocan Group northwest of the present map area. L i t t l e (I960) published the geology of the west half of the Nelson map area. He presents an excellent summary of earlier work in the area as well as a description of the Slocan Group and the Nelson Plutonic Rocks. e) Acknowledgements The writer i s indebted to Dr. A.J. Sinclair of the University of British Columbia for financial support of f i e l d and laboratory investigation through a N.R.C. grant. Dr. W.G. Libby, Dr. Sinclair and Dr. J.V. Ross provided guidance during a l l phases of the investigation. Special thanks are due Mr.Ted Eades, who served as f i e l d assistant and to Mr. L.McPherson who generously allowed the author to use his mine cabin as a f i e l d base camp. 5 B) GENERAL GEOLOGY a) Slocan Group Slocan Group i s composed of argillaceous sedimentary rocks with some interbedded impure quartzite and limestone. In the. area under study, this group has predominantly steeply dipping f o l i a t i o n which i s nearly parallel to bedding where both bedding and tectonic f o l i a t i o n were observed. The Slocan Group i s thought (Cairnes, 1934) to l i e disconformably above the Kaslo Greenstones which are exposed to the north-east . Slate and phyllite of the Slocan Group are black to grey-green regionally metamorphosed a r g i l l i t e . . Quartzite i s dark grey or black and near the contact with Mt. Carlyle stock contains iron oxides, biotite, and f i b r o l i t e . Limestone i s coarsely crystalline, grey, with lenticular beds ranging from a few inches to tens of feet in thickness. In the contact metamorphic aureole laminae of argillaceous and quartzose material delineate minor folds. Near the igneous contact the limestone becomes coarser grained and paler in color. Alternating pale to dark green layers in slates and phyl-l i t e s are a fraction of an inch thick. With increasing pro-ximity to the igneous contact this compositional layering becomes more marked and the color changes to alternating light grey and pinkish brown accompanying the development of anda-lusite, biotite and other metamorphic minerals. 6 G a i r n e s (1934) p l a c e d the source o f the S l o c a n Group sediments t o the west and p o s t u l a t e d a sha l low water depo-s i t i o n a l env i ronment . Hed ley (1952) s t a t e d t h a t the l a r g e , recumbent , S l o c a n f o l d i n the Sandon a rea was the r e s u l t , a t l e a s t i n p a r t , o f s t r e s s e s set up by the emplacement o f the Ne l son B a t h o l i t h south and eas t o f the a r e a . M a j o r f o l d axes are a lmost h o r i -z o n t a l except i n the a rea near the town o f Sandon where t h e y p lunge a t s m a l l ang le s to the northwest o r s o u t h e a s t . Near t o the c o n t a c t o f the Ne l son B a t h o l i t h and :. M t . C a r l y l e s t o c k Hed ley n o t i c e d t h a t the beds have been downbuckled and p lunges o f minor f o l d axes s t e e p e n . I r w i n (1951) made use o f p r i m a r y sed imentary f e a t u r e s and secondary s t r u c t u r e s i n the Howson Creek B a s i n to d e l i n e a t e a s e r i e s o f recumbent , n e a r - i s o c l i n a l f o l d s w i t h axes p l u n g i n g l e s s than 30°. These f o l d s t r e n d N45°W. Hyndman (196S) d i s t i n g u i s h e d t h r e e phases o f f o l d i n g i n the S l o c a n Group northwest o f the p r e s e n t a r e a o f s t u d y . The f i r s t phase o f d e f o r m a t i o n i n v o l v e d i n t e n s e i s o c l i n a l recum-bent f o l d i n g concommitant w i t h r e g i o n a l metamorphism. The second phase formed n e a r l y u p r i g h t f o l d s and a s t r a i n s l i p c leavage expres sed as c r e n u l a t i o n o f the f i r s t phase s c h i s t o -s i t y . The t h i r d d e f o r m a t i o n was due t o i n t r u s i o n o f C r e t a c e -ous g r a n i t i c p l u t o n s t h a t f o l d e d the s u r r o u n d i n g c o u n t r y r o c k s . 7 Irwin (1951) estimated the Slocan Group to be 3 7 , 0 0 0 feet thick based on the folding observed in the Howson Creek Basin and adjoining areas. Cairhes (in Irwin, 1952) objected to this estimate of thickness and considered a thickness of 7 , 0 0 0 feet to be a more reasonable figure. Hedley (1952) estimated a thickness of about 2 0 , 0 0 0 feet for the Slocan Group. The Slocan Group i s cut by numerous faults of small dis-placement and these are especially common near plutonic rocks. Cairnes (1934) described three small stocks northwest of the Mt. Carlyle stock as younger than 1 . Mt.Carlyle stock because they crosscut folds which he related to intrusion of the latter body. b) Nelson Plutonic Rocks Nelson Plutonic Rocks are composed of granite, quartz diorite, monzonite and syenite in order of decreasing abundance (L i t t l e , i 9 6 0 ) . Contact between these rock types i s gradatio-nal. K-feldspar phenocrysts are common in the granite and de-crease in size and number nearer the borders. Quartz content decreases, plagioclase and hornblende become more abundant, and the granitic rock tends to become foliated with increasing proximity to the borders of the plutons (Cairnes, 1 9 3 4 ) . Cairnes (1934) subdivided the Nelson Batholith into three gradational components: Nelson gneiss, Nelson granite and Nelson pegmatite gneiss. The Nelson granite was further 8 subdivided into three members: a crushed porphyritic granite, a massive porphyritic phase of the same granite, and a more equigranular rock of granitic to granodioritic composition. The porphyritic granite member i s gradationaliy zoned toward the borders of the batholith to granodiorite and quartz dio-r i t e . The Valhalla granitic complex to the west displays varied contacts with the Nelson porphyritic granite: interfingering, cutting, gradational ( l i t t l e , i 9 6 0 ) . L i t t l e (I960) suggest-two modes of emplacement for rocks included in a broad definition of Nelson Batholith: metasoma-tism of the pre-existing rocks based on the gradational con-tact between paragneiss and granite; magmatic injection based on crosscutting relations between contact phases of the gra-nite and the surrounding rocks. The core of the Nelson Batho-l i t h i s thought to have been emplaced at a great depth of burial. Thus, a complex history has been proposed for emplacement of Nelson Plutonic Rocks. Much of this complexity has arisen from confusion in delimiting the geographic extent of the Nelson Batholith. Reesor (1965) restricted the term Nelson Batholith to granitic rocks east of a large shear zone along the shore of Slocan Lake. South of the present area of study the Nelson Batholith i s thought to be of predominantly 9 magmatic origin. (Reesor, 1965; Libby, personal communi-cation.) c) Mt.Carlyle Stock Mt. Carlyle Stock, at the northern margin of the outcrop area of the Nelson Plutonic Rocks, i s a compositionally zoned piuton composed mainly of quartz monzonite, paler in color than Nelson Plutonic Rocks to the south. A partial rim of granodiorite encloses the quartz monzonite core and this grades locally into a diorite border phase. The quartz mon-zonite contains zones of K-feldspar phenocrysts up to two inches in length (Fig. 3 and 4). . Roof pendants in the northern part of the stock lend an irregular appearance to the stock. Xenoliths (up to one foot in length) occur throughout the stock but are most abundant in the northerly portions (Fig. 5 ) . The stock contact i s gradational in places with screens and inclusions of the surrounding metasediment within the granitic rock. Other parts of the contact are sharp and cross <cut the Slocan Group metasediment. Porphyritic and equigranular leucocratic and melanocratic dikes cut both i , Mt.Carlyle stock and the surrounding meta-sediment. Small plugs of diorite and quartz diorite intrude the contact metamorphic aureole surrounding the stock. The stock i s weakly foliated due to preferred orientation of hornblende and b i o t i t e . This f o l i a t i o n i s pronounced near the margin of the stock (Fig. 6 ) . \ 11 Figure 2: Looking North across the North branch of Montezuma Creek to Mt. Holmes. Part of a limestone roof pendant forms the white, tree covered, arcuate outcrop in the lower l e f t corner and the contact between Mt. Carlyle stock and Slocan group metasediments appears above the line of dwarf trees on the west side of Mt. Holmes in the upper center of the picture Figure 3 Quartz monzonite with large zoned K-f eldspar phenocrysts. The phenocrysts are zoned with concentric alignment of mafic inclusions. Sample collected east of Mt. Carlyle. Scale in inches. Figure l+: Large talus blocks of porphyritic quartz monzonite on the ridge separating the North and South branches of Montezuma Creek. Hammer on right provides scale. 12 Figure f>: One of the numerous biotite rich inclusions in the granodioritic phase of Mt. Carlyle stock. The sample i s weakly foliated paral-l e l to the surface showing in the photo. Sample collected on the ridge forming the West wall of the head of the Montezuma Creek Valley. Scale in inches. Figure 6: Foliated border phase of Mt. Carlyle stock. Sample collected at Southeast margin of the stock near the confluence of Long and Keen Creeks. Scale in inches. 13 II. STRUCTURAL ELEMENTS IN THE CONTACT REGION OF ' MT.- CARLYLE STOCK A) PRIMARY STRUCTURES Primary features recognized in the Slocan Group are cross-bedding, compositional layering and graded bedding. Irwin (1951) also reported ripple marks but none were seen by the author. Figure 7 shows crossbedding in quartzite collected near the southwest margin of . Mt.Carlyle stock one mile north of Mt.Heyland. Graded bedding i n interbedded quartzite and semischist is- common in the same area. Graded bedding and crossbedding are recognizable at a l l grades of metamorphism,. The s ense of gradation in grain size i s reversed resulting from development of porphyroblasts during metamorphic recrys-t a l l i z a t i o n . In the originally fine-grained argillaceous layers large andalusite crystals have grown and the originally coarser, quartz rich layers have recrystallized to siliceous hornfels composed of quartz, plagioclase, biotite, f i b r o l i t e and muscovite in decreasing order of abuncance. Original sedimentary layering has become emphasized by metamorphic recrystallization. Bedding i s commonly parallel or sub-parallel to a dominant mica fo l i a t i o n in the original-ly clay rich layers, figure g shows thin interbeds of anda-14 lusite-bearing and more quartz rich layers in a phyllite. Figure 9 shows original layering parallel to a strong, crenulated f o l i a t i o n in a phyllite. 15 Figure 7 : Crossbedding in quartzite from the South facing slope of the ridge 1 mile north-west of Mt. Heyland. Tops of beds are toward the bottom of the photo. Scale in inches. Figure £: Original layering in schist. The dark porphyroblasts are andalusite. Sample collected near the stock margin south of the lower portion of Montezuma Creek. Scale in inches. Figure 9: Original layering in phyllite. Note foliat i o n due to mica orientation parallel to the layering and crenulation of this foliation in the uncut surface. Curved lines on cut rock face are saw marks. Sample collected at the stock margin near the confluence of Long and Keen Creeks. Scale in inches. 16 B. SECONDARY STRUCTURES Secondary structures associated with the mode of emplace-ment of the stock, are best described by treating four areas along the stock margin seperately. These four areas are in -dicated on Figure 10 and w i l l be described starting with the southeast sector of the contact and proceding counter-clock-wise around the margin of the stock to the septum of Slocan Group metasediments that separate the stock from the Nelson Batholith to the south. Reasons for separating the contact region into four areas are twofold: the differing sharpness of the contact between the Slocan Group and the stock; the varying degree of devel-opment of foliation, kinks, faults and other features in the contact regions. FIG. 10 Map of Mt . C a r l y l e stock and four s t r u c t u r a l l y d i s t i n c t i v e areas i n the contact reg ion of the stock 18 a) Area I In the f i r s t area foliated, but otherwise relatively homo-geneous granitic rock grades through 100 to 250 feet of inter-layered granitic and schistose rock to metasediment essenti-a l l y free of granitic layers. This gradational contact can be divided into four belts parallel to the stock margin and each displays gradational internal relations, grading into one another along r a d i i drawn out from the center of the stock. These are summarized as follows. The border phase of the stock in this area i s hornblende and biotite quartz diorite with K-feldspar phenocrysts simi-lar to those found in varying numbers in the interior of the stock. The quartz diorite commonly is foliated due to paral-l e l alignment of hornblende and bi o t i t e . Figure 6 i s a photo-graph of this igneous border phase. Quartz diorite grades to a belt of oriented screens of schist within granodioritic material. Metasedimentary screens are oriented vertical or dip steeply outward from the stock. The rocks in this belt differ from the gneiss belt, described next, in the scale at which the schistose and granitic material is interlayered. Screens of schist are one-half to three feet thick becoming gneissic at their margins where they grade into granitic material. Figures 11, 12 and 13 show shistose screens. 19 Figure 11: Screens of schist intermixed with granitic rock. These rocks are transitional between typical screen development and gneiss. Photo taken near the confluence of Long and Keen Creeks. Scale given by hammer, pen and nickel. Figure 12: Irregular screens of schist and gneiss from the same local i t y as Figure 11. The screens trending from lower l e f t to upper right parallel the stock margin. Scale given by hammer, pen and nickel. Figure 13: Screen of metasediment in granitic rock. Note vein in center of photo that pinches and swells in the metasediment. Photo taken at stock margin east and south of Mt. Carlyle. Scale given by hammer, nickel and pen. 2 0 Screens have tightened minor folds within the schistose fol i a t i o n which i s roughly parallel to the margin of the stock. Figures 14 and 15 show the folds just described and also show the metamorphic segregation of the schists into very thin bio-t i t i c and quartzofeldspathic laminae. The screen belt grades outward from the stock into a belt of gneiss consisting of thin interlayers of metasediment and quartzofeldspathic rock. Within this belt biotite has been partially isolated in ring shaped and planar concentrations surrounding and interfingering with fine-grained quartzofeld-spathic lenses less than one inch thick. Figures 16 and 17 show samples of gneiss with layering and mafic segregation. The gneiss belt grades outward into schist of the Slocan Group metasediments characterized by nearly i s o c l i n a l folds with axial planes parallel to the fol i a t i o n . This f o l i a t i o n parallels the steeply dipping contact region and the gneissic folia t i o n in the contact belts described above. Foliation of the schists i s gently warped around cuspate apophys.e. s of the stock. A crenulation in the folia t i o n just described i s developed locally along the eastern margin of Mt. Carlyle stock (Fig. 26) but i s much more pronounced along the western margin des-cribed below. Slocan Group schists in Area 1 are locally cut by 21 pegmatitic material in the outer parts of the gradational contact. This phenomenon i s illustrated in Figures Id and 19. 22 Figures 14 and 15: Folds in screens at the stock margin with thin lamination of quartzofeldspathic and b i o t i t i c material. Laminations meta-morphic segregation possibly along original bedding in the schist. Scale i s in inches. Figure 16: Gneiss composed of thin, highly irregular bands of dark grey schistose rock and light colored granodioritic material. Sample collected at the stock margin where i t crosses the ridge separating Keen and Montezuma Creek Valleys. Scale in inches. 23 of Figure 17* Gneiss with ring-like concentration biotite. 1 collected in the stock contact region from the same area as Figure 16. Curved lines on rock surface are saw marks. Scale in inches. Figure 18 and 19* Pegmatite in schist and gneiss from the outer part of gradational contact of the Mt. Carlyle stock. Bondina ged pegmatite appears in Figure 19. Samples are from the southeast and east part of the stock margin. Scale in inches and given by the hammer, nickel and pen. 24 b) Area II In this area the contact between Mt. Carlyle stock and Slocan metasediment is sharp in single outcrops but i s grossly gradational when considered over a distance of several thousand feet (Fig. 10 and Plate 1). Reentrants and roof pendants of metasediment several hundred to several thousand feet in length are common (Fig. 21 and Plate 1) along the stock margin. The contact dips steeply outward from the stock throughout most of this area and the mapped "irregularity i s not a topographic effect. (Plate 1) The amount of quartz rich metasediment and especially of limestone in the reentrants and roof pendants is much greater than in the nearby contact zones. Foliation in the metasediment strikes into the stock, often at a high angle to the contact. The parallelism of tectonic foliation and stock margin described in other contact areas i s absent here. Andalusite porphyroblasts developed in this area are randomly oriented, occuring both within the plane of domi-nant fo l i a t i o n and at various angles to i t . This lack of orientation contrasts with contact areas to the west and south where andalusite porphyroblasts are arranged within the dominant fol i a t i o n . Limestone in the roof pendants i s intensely folded as delineatedby thin argillaceous layers. The folding is 25 both concentric and disharmonic with variably oriented fold axes and „is probably related to emplacement of the surroun-ding granitic rock. These folds are shown in Figures 22 and 23 and the roof pendant containing them is seen in Figure 2 1 . Plate 1 (if mile WNW of Mt. Holmes) shows fol i a t i o n and fold axis measurements of a megascopic fold believed to be an accomodation structure related to emplacement of the stock. The folded beds are thin bedded impure argillaceous limestone, biotite schist, and quartzite in order of decreasing abundance. The fold i s centered in a reentrant of metasediment between the main body of the stock to the southeast and an extension of the stock to the northwest. The northernmost portion of Area 2 is characterized by a moderately steep contact that crosscuts the dominant fo l i a t i o n in the country rocks. Large dilation dikes and s i l l s occur above the contact where i t dips under the metasediments. 26 Figure 20: View looking northwest toward a large roof pendant at the head of the north branch of Montezuma Creek in the northern portion of Mt. Carlyle stock. The roof pendant i s the dark area underlying the sumnjit of the moun-tain in the photo. The roof pendant i s com-posed of argillaceous limestone. toward Figure 21: View looking north a limestone roof pendant in Mt. Carlyle stock in the valley of the nort'h branch of Montezuma Creek. The roof pendant i s the arcuate septum of outcrop just below tree line in the upper center of the photo. 27 Figures 2 2 and 2 3 : Tight f o l d i n g i n the limestone roof pendant whown i n Figure 2 1 . The f o l d i n g i s del ineated by-bands of arg i l laceous mater ia l that i s more competent than the l imestone. Hammer and compass give sca le . 2o c) Area III The third structurally distinct area in the contact region of Mt. Carlyly stock i s characterized by well developed crenu-lation of the dominant foliation, sharp contact between the stock and the metasediments,numerous large laucocratic por-phyry dikes, tightly crumpled fault zones, drag folds and a foliated border phase of Mt. Carlyle stock. The dominant foliation in this area i s sub-parallel to the margin of the stock. T h i s orientation i s probably the result of warping of a pre-existing regional foliation during em-placement of the stock. The dominant mica foliation i s strongly crumpled in outcrop and crenulated in handspecimen near the stock margin. In thin section the crenulation i s seen to result from intersecting s l i p cleavages which have offset contact metamorphic porphyroblasts. * i g U r e s 24, 25 and 26 show crenulation of a previous f o l i a t i o n . The contact i s normally sharp in this area and large leuco-cratic dikes have intruded along fractures, bedding planes and other zones of weakness in the metasediments. Drag folds in limestone with fold axes contained in a plane approximately parallel to the margin of Mt. Carlyle stock have sense of movement indicating that the metasediments nearer the contact have moved up and laterally relative to those farther 29 from the contact, The drag folds are.tighter and less sym-metrical than folding observed elsewhere in the limestone (figures 22 and 23). A zone of intense crumpling and strong fracture cleavage appears as a lineament in aerial photographs near the stock contact. The border phase of the stock i s well foliated in the southernmost portion of Area III. The contact here i s sharp and regular with well developed crenulation of the dominant folia t i o n in the metasediments. 30 Figure 2J+: Strain-slip cleavage which crenulates the previous layering and mica foliation and has disoriented andalusite porphyroblasts (white spots in photo). Sample collected in the south wall of the Twelve Mile Creek valley near the stock contact. Scale in inches. Figure 25: Intensely crumpled folia t i o n ih pelite collected at the stock margin two miles north of Mt. Heyland. Scale in inches. Figure 26: Intersecting crenulation cleavages seen in the plane of the dominant mica f o l i a t i o n . The foli a t i o n i s sub-parallel to the stock margin. Sample collected 1 mile west of the confluence of Keen and Montezuma Creeks. Scale in inches. 31 d) Area IV The fourth structurally d i s t i n c t i v e area i s the septum of Slocan Group metasediments between Mt. Carlyle stock and the northern margin of the Nelson Batholith. The struc-tures attest to a possible earlier emplacement of the batho-l i t h relative to the stock to the north. A well developed foli a t i o n i s ubiquitous and in the eas-tern and central portions of the area maintains a consistent strike of approximately 1 2 0 ° and a steep or vertical dip. This fo l i a t i o n strikes approximately parallel to the margin of Mt. Carlyle stock. Crenulation in this fo l i a t i o n i s shown in Figures 9 , 2 7 , and 2&. Minor folds are well developed in the fol i a t i o n near the border of Mt. Carlyle stock. With increasing proximity to the southwest margin of the stock the minor folds tighten and become sheared out as shown in Figures 29 and 3 0 . Near the margin of the Nelson Batholith in the septum, minor folds have been deformed such that their axial plane cleavages fan slightly and approximately parallel the margin of the Nelson Batholith. These folds are offset by two intersecting fracture cleavages, one of which may develop preferrentially to the other. The fracture cleavage i s locally the locus of incipient small fractures of f i n i t e relative displacement which offset the limbs of minor folds 32 as seen i n Figures 31 and 3 2 . The fracture cleavages i n t e r -sect at angles averaging approximately 30°, Intersecting fracture cleavages define a parting i n the rock allowing p r i s -matic breakage recognizeable i n hand specimen. The l i n e a t i o n defined by the int e r s e c t i o n of the conjugate fracture cleavages i s steeply plunging. Compton (1955) described s i m i l a r f r a c t u -re ( s l i p ) cleavages a t t r i b u t i n g t h e i r development to forces set up by an intru s i v e pluton a f t e r development of the domi-nant s c h i s t o s i t y i n the country rocks. The fracture cleavages are oriented such that the plane of f o l i a t i o n intersects the acute angle between them. A possible explanation f o r t h i s orientation i s that the fracture cleavages resulted from t i g h -tening of e a r l i e r f o l d s due to i n t r u s i o n of Mt. Carlyle stock. A weak f o l i a t i o n s i m i l a r to secondary f o l i a t i o n i n other parts of the septum occurs with the s l i p cleavages and intersects the main mica f o l i a t i o n at a low angle. This weak f o l i a t i o n and possibly the accompanying fracture cleavages are thought to be related to int r u s i o n of Mt. Carlyle stock to the north. Nearer the southwest margin of the stock the dominant country rock f o l i a t i o n i s sub-parallel to the f o l i a t e d border of the stock. The f o l i a t i o n i s cut by large crumples and crenulation i n the schistose layers and minor fo l d s are sheared out and discontinuous. Joints are abundant i n rocks of the septum, e s p e c i a l l y 33 Figure 2 7 : Foliated metapelite containing andalusite and garnet porphyroblasts. The porphyroblasts are in augen-like distortions in the dominant mica fol i a t i o n . Sample collected near the stock contact north of the confluence of Long and Keen Creeks. Scale in inches. Figure 2 8 : Foliation in metapelite containing large anda-lusite porphyroblasts. Sample collected g mile north of Mt. Heyland. Scale in inches. Figures 29 Original layering and some reversed graded and 3 0 : bedding sub-parallel to foliation in p e l i t i c schist | mile northeast of Mt. Heyland. Minor folds are defined by light and dark layering and are much sheared and tightened. The darker layers have large andalusite porphyro-blasts. Scale given by hammer, pen and quarter. f i 5 . 2 7 34 Figure Figure Figure 3 1 : Minor folds in interbedded pelite and quartz-ite beds. The two rock types are in dark and light colored layers. Note fanning of the axial plane cleavage visilbe at the top of the photo. Sample collected near the margin of the Nelson Batholith 2 | miles northwest of Mt. Heyland. Scale in inches. 3 2 : Minor folds with a small fault that has dis-placed the limb of the fold on the l e f t in the photo. The small fault parallels a fracture cleavage making a small angle with the dominant mica fo l i a t i o n . Sample collected near where that in Figure 31 was collected. Scale in inches. ' 3 3 : Blocks of p e l i t i c schist with large andalusite porphyroblasts within the fo l i a t i o n . The block on the l e f t i s observed along the foliation and the block on the right in the photo i s ob-served normal to the foli a t i o n . . Sample collec-ted ^ mile northeast of Mt. Heyland. Scale given by peri and quarter. 35 where small faults were recognized. One of these fault zones, indicated on Plate 1 upstream from the mouth of Long Creek, contains a dark grey mylonite along closely spaced fractures. Large chiastolite porphyroblasts in the central and wes-tern part of Area IV show internal features not seen in s i -milar porphyroblasts elsewhere in the contact region of Mt. Carlyle stock. The crystal structures here are pertinent to the sequence of emplacement of the Nelson Batholith and Mt. Carlyle stock to the north. Chiastolite porphyroblasts having internal features described below appear in Figure 3 4 , 3 5 , 3 6 , and 3 7 . In this area chiastolite i s seen in thin section to con-tain abundant elongate quartz inclusions. The inclusions, as well as cleavage traces in the crystals, are deformed and meet the surrounding groundmass folia t i o n at variable angles. Lenticular quartz inclusions may have assumed their present shape during a deformation previous to that which produced the present crenulated f o l i a t i o n in the rock. Crystals en-closing deformed quartz lenticles exhibit no strained extinc-tion patterns. Some evidence of strain would be expected i f the porphyroblasts had not recrystallized after deformation of the enclosed quartz lenticles. The amount of internal crystal deformation i s independent of the present crystal 36 Figure 3 4 : Chiastolite with deformed cleavage and small rod-like inclusions of quartz. The crystals are rimmed by a sericite border. Sample col-lected | mile northeast of Mt. Heyland. Figure 3 5 : Chiastolite with oriented inclusions in the central part of the crystal. Wedge shaped reentrants of the groundmass of the rock occur in the l e f t and right side of the crystal and curved cleavage and quartz in-clusions are vi s i b l e . Sample collected 1 mile downstream from the head of Long Creek. Figures 36 and 3 7 : Chiastolite with deformed lenticular quartz inclusions. Sample from the same locality as that shown in figure 3 5 . 37 orientation. The inclusion-rich central area and wedge-like reentrants of the groundraass in the crystal in Figure 35, in-tersect the groundmass fo l i a t i o n at a distinct angle. This suggests that the deformation that aligned the inclusion-rich areas was distinct from that producing the present groundmass foli a t i o n . The ultimate character of the chiastolite porphyroblasts i s the result of a growth in stages yielding concentric zones of slightly different extinction orientation within the same crystal. Occassional "piggy-back" chiastolite growth has resulted in two well developed chiastolite porphyroblasts sharing a common surface but with each crystal having a dis-tinct chiastolite inclusion cross. Many of the andalusite crystals are surrounded by a rim of s e r i c i t i c alteration material. In one locality at the mar-gin of Mt. Carlyle stock northeast of Mt. Heyland s e r i c i t i c alteration material i s completely pseudomorphic after large andalusite crystals. Thin sections containing deformed chiastolite porphyro-blasts also contain smaller knots of sericite-chlorite a l -teration material. These smaller knots are the same shape as fresh cordierite porphyroblasts at the margin of the Nelson Batholith one mile northwest of Mt. Heyland. Iden-t i f i c a t i o n of the chlorite knots as former cordierite 38 porphyroblasts remains speculative owing to lack of rem-nant cordierite within the knots and scant outcrop control. 39 C. TEMPORAL RELATIONS BETWEEN THE  NELSON BATHOLITH AND MT. CARLYLE STOCK: SUMMARY Structural features related to the M t .Carlyle stock have been interpreted as being later than minor folds and f o l i a -tion related to the emplacement of the Nelson Batholith to the south. These features have been described in the pre-vious section and some of the structural features appear on Plate 1. The large chiastolite porphyroblasts described in the previous section suggest multiple deformation and thermal metamorphism in the septum of Slocan Group metasediments between the Nelson Batholith and Mt. Carlyle stock. A pos-sible history for the chiastolite porphyroblasts i s : 1) Regional deformation followed by refolding of the low grade metamorphic rocks during emplacement of the Nelson Batholith and development of a foli a t i o n parallel to the mar-gin of the Nelson Batholith. The f i r s t chiastolite porphyro-blasts grew at this time, possibly with small cordierite crystals. 2) A third period of deformation due to emplacement of Mt. Carlyle stock with straining and later recrystallization of chiastolite crystals. The crystals retain a record of deformation in the form of lenticular quartz inclusions and curved cleavages and are oriented parallel to the foli a t i o n 40 which p a r a l l e l s the southern margin of Mt. Carlyle stock, suggesting r e c r y s t a l l i z a t i o n related to emplacement of the stock. 3) Late retrograde metamorphism producing s e r i c i t e pseudomorphs a f t e r c h i a s t o l i t e and s e r i c i t e - c h l o r i t e pseudo-morphs afte r c o r d i e r i t e near the margin of Mt. Carlyle stock. -D. MODE OF EMPLACEMENT  OF MT. CARLYLE STOCK Compton (1955, I960) and Pitcher (1963) discuss manner of emplacement of igneous plutons i n r e l a t i o n to structures and thermally metamorphosed country rock surrounding the plutons. Features of the contact region of Mt. Carlyle stock are i n d i -cative of the sty l e of emplacement of the stock. A broad zone of intermixing of metasediment and g r a n i t i c rock along the eastern margin of the stock indicates some degree of assim i l a t i o n of the metasediment by the stock. Feld spathisation of the metasediment has produced quartzofeld-spathic gneiss i n the gradational contact area. B i o t i t e has become segregated i n the metasediment i n the contact zone. In the northern portion of the stock numerous xenoliths and roof pendants attest to p a r t i a l incorporation of the meta sediment into the igneous rock. Calcareous metasediments l o c a l l y s t r i k e into the stock and are abruptly crosscut by 41 the stock margin. It i s t h i s area of the stock that was shown by S i n c l a i r and Libby (1967) to be high i n Ca content r e l a t i v e to the southern portions of the stock. S i n c l a i r and Libby (1967) postulate a magmatic o r i g i n for the stock with possible contamination i n the northern portion. The swing of regional f o l i a t i o n into p a r a l l e l i s m with the stock margin i s s t r i k i n g . This suggests some accommodation of the stock by the surrounding metasediment. Along the north and west margins of the stock igneous dikes of composition si m i l a r to that of the stock have i n -truded along planes of weakness i n the countryrock. Crumpling and f r a c t u r i n g of the surrounding rocks increasing i n inten-s i t y nearer the stock margin possibly indicates late shoulder-ing by the p a r t i a l l y cooled igneous rock. Well developed f o l i a t i o n i n the igneous border phases where the contact with the metasediment i s sharp indicates shearing or f l a t t e n i n g near the borders of the stock. Magmatic o r i g i n of the stock i s suggested by the complex zoning and combination twinning of plagioclase. The marked contact metamorphic aureole around the stock indicates the stock was a source of heat f o r the surrounding metasediments. Tight f o l d s with a x i a l planes co-planar with f o l i a t i o n p a r a l l e l to the stock margin indicate shearing p a r a l l e l to and f l a t t e n i n g perpendicular to the stockmargin. 1 42 A simple mechanism of emplacement i s not compatible with various features presented above and a combination of pro-cesses must be1 invoked. A magmatic body of molten rock was intruded into the Slocan Group metasediment by a process of l a t e r a l accommodation, f o r c e f u l shouldering, and assimila-t i o n i n order of decreasing importance. The border phases of the cooling stock were f o l i a t e d p a r a l l e l to the stock margin during emplacement. I I I . METAMORPHISM A. SLOCAN GROUP SEDIMENTARY ROCKS The non-metamorphic rock types of the Slocan Group have been described i n a general way by Cairnes (1934) and Hedley (1952) but no detailed stratigraphy has been proposed f o r the group. The present author has been unable to follow any stra-tigraphic horizon as i t passes from the regional greenschist metamorphic terrane into the contact regions of Mt.Carlyle stock. However, the "slate b e l t s " described by Hedley can be projected along s t r i k e to meet Mt-. Carlyle stock and a gene-r a l c o r r e l a t i o n of contact metamorphic rocks with t h e i r o r i -g i n a l rock- types can be made. This procedure a l l o c s no detailed control of the degree to which the Slocan Group has been altered i n chemical composition during contact meta-morphism. 43 ; Contact metamorphic rocks in Mt. Carlyle region are dis-cussed under five headings based on the present composition of the metamorphosed Slocan Group sedimentary rocks. The five compositional divisions distinguished in the present discus-sion are: limestone-marble association, quartzite, potassic to calcic pelite, magnesian pelite, and ferrous pelite. Areas dominated by each of these rock associations are indi -cated on Plate 1. B. LIMESTONE-MARBLE ASSOCIATION Calcareous rocks in the contact aureole of Mt. Carlyle stock are predominantly impure coarsely crystalline limestone and marble. Carbonate units are most common along the north-east margin of the stock and in roof pendants in the same region. Crystal size of calcite in the carbonate units i n -creases with proximity to the stock contact. The limestones are pale grey where small amounts of argillaceous and carbona-ceous impurities are present; the color grades to black with increasing impurities. The calcareous layers vary in thickness from a few inches to 300 feet. Minor folds are developed prominently in the limestone near the contact with Mt. Carlyle stock. Contact metamorphic s i l i -cate minerals are not obviously abundant in hand specimens from most l o c a l i t i e s . Garnet has been reported in calcareous 44 units in the contact aureole but was not observed by the present author. Figure 3& shows typical thin bedded impure limestone from the contact region of Mt. Carlyle stock. C. QUARTZITE Quartzose metasediments are most abundant along the western margin of Mt. Carlyle stock (Plate l ) and in some of the roof pendants in the northern portion of the stock. Much of the quartzite i s pinkish, due to biotite and f i b r o l i t e . Very near the-stock contact the quartzite i s horn-f e l s i c in appearance although mica folia t i o n locally i s weak-ly developed. Along the western margin of the stock quartzite commonly is restricted to thin bedded coarse grained members of graded beds. Near the stock contact the quartzite increases in K-feldspar content as muscovite i s depleted and f i b r o l i t e mats develop rimming K-feldspar and biotite. Figures 39 , 40, and 41 show f i b r o l i t e mats growing in a K-feldspar-plagioclase-biotite-muscovite groundmass. 45 F i g u r e 3-3* T h i n bedded l i m e s t o n e w i t h l a y e r s more o r l e s s r i c h i n a r g i l l a c e o u s and c a r b o n a c e o u s i m p u r i t i e s . Samples c o l l e c t e d on t h e n o r t h s l o p e s o f M t . H o l m e s . S c a l e i n i n c h e s . F i g u r e 39 : L a m i n a t e d f i b r o l i t e - b i o t i t e mats a d j a c e n t t o a p e g m a t i t e v e i n ' i n t h i n l y i n t e r b e d d e d q u a r t a -i t e and s c h i s t . A f l a k e o f m u s c o v i t e c r o s s -c u t s t h e f o l i a t i o n i n t h e l o w e r l e f t c o r n e r o f t h e p h o t o . Sample c o l l e c t e d n e a r t h e c o n -t a c t o f M t . C a r l y l e s t o c k 3 m i l e s n o r t h o f M t . H e y l a n d . F i g u r e 4 0 : F i b r o l i t e b u n d l e s w i t h b i o t i t e and some mus-c o v i t e i n a q u a r t z - f e l d s p a r groundmass . Sample c o l l e c t e d i n a q u a r t z i t e r o o f pendant a t t h e e a s t e r n m a r g i n o f M t . C a r l y l e s t o c k . F i g u r e 4 1 * F i b r o l i t e w i t h b i o t i t e r i m m i n g q u a r t z and f e l d s p a r g r a i n s . Same t h i n s e c t i o n as t h a t shown i n * i g u r e 4 0 . 46 D . K - G a R I C H P E L I T E P e l i t i c r o c k s t y p i c a l l y r i c h i n a n d a l u s i t e , m u s c o v i t e , a n d p l a g i o c l a s e o c c u r i n t e r l a y e r e d w i t h t h e o t h e r m e t a -s e d i m e n t a r y r o c k t h r o u g h o u t t h e c o n t a c t a u r e o l e o f M t . C a r l y l e s t o c k . K - a n d C a - r i c h r o c k i s e s p e c i a l l y a b u n d a n t a l o n g t h e n o r t h w e s t m a r g i n o f t h e s t o c k . ( P l a t e 1) F i g u r e 42 s h o w s a s a m p l e w i t h l a r g e p a r t i a l l y s e r i c i t i z e d c h i a s t o l i t e g r a i n s r a n d o m l y o r i e n t e d i n a f o l i a t i o n p l a n e . F i g u r e 43 i s a p h o t o m i c r o g r a p h o f t h e same r o c k . T h e s e r i c i t e r i m s a r e v i s i b l e i n t h i n s e c t i o n . F i g u r e s 44 a n d 45 s h o w c r e n u l a t i o n s i n a f o l i a t i o n w h i c h p a r a l l e l s t h e s t o c k m a r g i n . T h e c r e n u l a t i o n s r e s u l t f r o m s t r a i n s l i p c l e a v a g e p a r a l l e l t o t h e i r a x i a l p l a n e s (Fig.45) w h i c h h a s d e f o r m e d a n d f r a g m e n t e d a l t e r e d a n d a l u s i t e p o r p h y -r o b l a s t s i n a m u s c o v i t e - q u a r t z m a t r i x . T h e s e h i g h l y p o t a s -s i c p e l i t e b e d s a r e i n a r e g i o n a l o n g T w e l v e M i l e C r e e k c u t b y fcany s m a l l f r a c t u r e s a n d i n t e n s e c r e n u l a t i o n p r o b a b l y r e -l a t e d t o l a t e s t a g e s h o u l d e r i n g o f t h e c o u n t r y r o c k b y M t . C a r l y l e s t o c k . 47 Figure 4 2 : Chiastolite porphyroblasts in random orien-tation within a foliation plane in metapelite. Sample collected near the stock margin on the north wall of the Twelve Mile Creek valley. Scale in inches. Figure 43* Chiastolite porphyroblasts with sericite rims set in a muscovite rich groundmass. Thin sec-tion of the same sample as shown in Figure 4 2 . Figure 44* Crenulation in layered metapelite. Note cata-clastic appearance of the light quartz grains. Foliation parallel to the layering i s due to alignment of muscovite and graphite. Sample collected in south wall of the Twelve Mile Creek valley. 48 E. MAGNBSIAN PELITE Cordierite (Fig. 46) was recognized in only one outcrop, at the northwest margin of the Nelson Batholith near the western termination of the septum of Slocan Group metasedi-ments separating the batholith from Mt. Carlyle stock. The large outcrop consists of banded light green to grey quartz-ose rock, and dark grey to pinkish schist. The cordierite is in knots that appear as black spots on a smooth unweather-ed surface, as brown rough knots on a partially weathered surface, and as small pits on an intensely weathered surface. In the cordierite-bearing layers the foliation of the schist i s defined by orientation ofmmuscovite and biotite. The pinkish cast on the foliat i o n surfaces i s due in part to bio-t i t e but i s especially noticeable where f i b r o l i t e mats are developed. The dominant foliation i s subparallel to original sedimentary layering. Some crossbeds are apparent in the quartzose layers and are distinguished by concentration of dark minerals along the crossbeds. In thin section the cordierite i s poikiloblastic in diamond or lens-like porphyroblasts. Small biotite inclusions in cor-dierite are orientated parallel to the biotite in the surroun-ding groundmass. The biotite inclusions are surrounded by 4 9 pleochroic halos. Loca l l y , the c o r d i e r i t e porphyroblasts share common boundaries and make up 75 percent of the rock. The groundmass minerals are muscovite, quartz and plagioclase i n decreasing order of abundance. Sigmoidal i n c l u s i o n t r a i n s i n the c o r d i e r i t e were not ob-served, thus the growth may have been s t a t i c . Some of the porphyroblasts have "hatchure" polysynthetic twins as well as pseudohexagonal penetration twins. B i o t i t e and muscovite are concentrated around the cordie-r i t e porphyroblasts giving a "chain l i n k " appearance to the rock where the co r d i e r i t e porphyroblasts are c l o s e l y spaced. Figures 47 and 1+8 show c o r d i e r i t e i n t h i n section. Material from c o r d i e r i t e knots was x-rayed at a scanning speed of k° per minute from 29°-30° 2©, and an average d i s t o r -t i o n index was calculated using r e l a t i v e peak .positions f o r r e f l e c t i o n s (511) (421) and (131). The d i s t o r t i o n index increases i n proportion to the devia-t i o n of the c o r d i e r i t e from i t s hexagonal polymorph i n an order-disorder r e l a t i o n s h i p . (Miyashiro, 1957). The d i s t o r t i o n index (A) i s given by the following r e l a t i o n s h i p : D 2 Where 2©^ 2Qg and 2©^ are the deviation angles i n degrees of the peaks representing (511), (421) and (131) respectively. A i n the present case i s 0.25 i n d i c a t i n g that the c o r d i e r i t e i s 50 intermediate between h i g h l y d i s t o r t e d c o r d i e r i t e and un-d i s t o r t e d i n d i a l i t e . 51 Figure 4 5 * Sericitized andalusite porphyroblasts in a muscovite-quartz matrix. Strain s l i p cleavage i s near vertical in the photo and has graphite concentrated along the cleavage planes. A lesser developed strain s l i p cleavage inter-sects the prominent strain s l i p cleavage shown here. Sample collected in same area ss that shown in Figure 4 4 . Figure 4 6 : Cordierite knots in schist appearing as brown spots on a weathered surface. Sample collected near the margin of the Nelson Batholith 2\ miles northwest of Mt. Heyland. Figures 47 Cordierite porphyroblasts il l u s t r a t i n g poiki-and 48 * loblastic texture with inclusions of biotite and quartz. Biotite-muscovite intergrowths in the groundmass are oriented in a folia t i o n and the biotite-muscovite i s arranged in a chain-like pattern around the cordierite porphyro-blasts. Sample i s the same as that shown in Figure 4 6 . 52 F. FERROUS PELITE A narrow band of Fe p e l i t e borders Mt. Carlyle stock along i t s southeast margin. I t i s i n t h i s band that the only s t a u r o l i t e and garnet were recognized i n the map area. Some of the te x t u r a l relationships of the Fe-pelites are included i n t h i s section and'are summarized i n Figure 49 where the number of observed instances of contact of the various mineral phases i s recorded. The c o r d i e r i t e i n d i c a -ted on t h i s table i s from the Mg-pelite at the northwest mar-gin of the Nelson Batholith. F i r s t occurrences of the key contact metamorphic minerals i n the region surrounding Mt. Carlyle stock are indicated on the isograd map, Figure 50. Mineral assemblages i n the con-tact metamorphic rocks are indicated i n projection i n the A'FM plane (Thompson, 1957) of the A-K-F-M tetrahedron i n Figure 51. Similar A'FM diagrams were employed by Green (1963) i n representing regional and contact metamorphic mineral as-semblages from northern New Hampshire. Possible reactions which produced the observed mineral assemblages are l i s t e d i n Figure 50b. Staurolite and garnet f i r s t appear i n the contact aureole of Mt; Carlyle stock i n the same outcrops. Thus, i n most areas the s t a u r o l i t e and garnet isograds are superimposed i n Figure 51. CHLORITE BIOTITE GARNET STAUROLITE ANDALUSITE SILLIWAMTE CORDIERITE MUSCOVITE BIOTITE G A R N E T STAUROLITE ANCALU SITE SILLIMANITE C O R D I E R I T E F I G . 49 T a b l e o f o c c u r r e n c e s o f common b o u n d a r i e s between m i n e r a l phases i n the c o n t a c t metamorphic a u r e o l e o f M t . C a r l y l e s t o c k f i g . 5 0 Map of Mt. Carlyle stock and inferred isograds in the contact metamorphic aureole 55 MINERAL ASSEMBLAGES chlorite - albite - quartz Regional p h y l l i t i c greenschist biotite - plagioclase - quart + chlorite andalusite - biotite - plagioclase - quartz staurolite - biotite - plagioclase - quartz + andalusite garnet - biotite - plagioclase - quartz + andalusite garnet - staurolite - andalusite - plagioclase + quartz cordierite - biotite - plagioclase - quartz sillimanite - biotite - muscovite -- plagioclase - quartz Sillimanite + biotite + K-feldspar + plagioclase + quartz PROPOSED MINERAL REACTIONS ' 1. Chlorite + muscovite andalusite + biotite + quartz + HgO 2. Chlorite + muscovite + quartz cordierite + biotite + rL,0 3. Fe-Mg chlorite + quartz Almandine + Mg-chlorite 4. Garnet + biotite + andalusite staurolite + muscovite + h^ O + quartz 5. Andalusite ±^ sillimanite 6. Muscovite + Quartz K-feldspar + sillimanite + h^ O Fig. 50b Mineral assemblages and possible mineral reactions in p e l i t i c metasediment from the contact aureole of Mt. Carlyle stock. Muscovite -H Sf Muscovite co Muscovite o o Muscovite co o :>  Muscovite -•p •H X u Muscovite -P-. •H CQ ct$ CD o Andalusite M Muscovite P y r o p h y l l i t e 56 A*FM diagrams for contact metamorphic assemblages i n the aureole of Mt. C a r l y l e stock. FIG.51 57 Figures 5 2 , 5 3 , 5 5 , and 56 show typical textural rela-tionships between garnet and staurolite and the relationships of these minerals to andalusite and biotite. Figure 52 shows a subhedral staurolite and a euhedral gar-net in the same b i o t i t i c f o l i a t i o n . Graphite inclusions which are aligned with biotite in the fol i a t i o n remain in the stau-r o l i t e and continue as a component of the groundmass foliation after passing through the staurolite crystal. The same cross-cutting relation between a large garnet porphyroblast and the groundmass fol i a t i o n i s seen in Figure 6 0 . Individual graphi-te inclusions in some instances remain intact where they cut the boundary between a staurolite porphyroblast and the f o l i a -ted groundmass. Crenulationsin the groundmass folia t i o n are recorded in inclusion trains within the staurolite grains and possibly indicate a static growth of the porphyroblast after the deformation which crenulated the groundmass f o l i a t i o n . Figure 53 shows two staurolite porphyroblasts with curved i n -clusion trains which pass undeflected into the groundmass f o l i -ation. Small euhedral garnet porphyroblasts show no evidence of ro-tation or cataclasis and are commonly included in biotite rich areas of the groundmass fo l i a t i o n . (Figure 5 2 . ) Chiastolite porphyroblasts i n the Fe-pelite have grown in multiple stages recognizable as composite overgrowths with 5 8 F i g u r e 52: A s u b h e d r a l s t a u r o l i t e p o r p h y r o b l a s t ( l e f t c e n t e r ) a n d a e u h e d r a l g a r n e t ( r i g h t c e n t e r ) i n b i o t i t e f o l i a t i o n . G r a p h i t e , f o r m i n g p a r t o f t h e f o l i a t e d g r o u n d m a s s , p a s s e s a s i n c l u -s i o n s t h r o u g h t h e s t a u r o l i t e c r y s t a l . S a m p l e c o l l e c t e d n e a r t h e s t o c k m a r g i n i n t h e w e s t w a l l o f K e e n C r e e k s o u t h o f M o n t e z u m a C r e e k . F i g u r e 53* Two s t a u r o l i t e p o r p h y r o b l a s t s r e t a i n i n g i n c l u -s i o n t r a i n s o f g r p h i t e similar t o t h e g r a p h i t e g r a i n s i n t h e g r o u n d m a s s f o l i a t i o n w h i c h m e e t s t h e s t a u r o l i t e c r u s t a l a t a h i g h a n g l e . S a m p l e i s t h e same a s t h a t s h o w n i n f i g u r e 5 2 . F i g u r e 54* A n d a l u s i t e c r y s t a l t h a t h a s f o r m e d d u r i n g t h r e e s t a g e s o f g r o w t h : S t a g e 1 4. T h e i n c l u s i o n f r e e z o n e j u s t t o t h e ! l e f t o f t h e c e n t e r o f t h e p h o t o S t a g e 2 - I n c l u s i o n r i c h z o n e i r r e g u l a r l y d e v e l -o p e d s u r r o u n d i n g t h e i n i t i a l s t a g e o f t h e c r y s t a l S t a g e 3 - O u t e r p o r t i o n o f t h e c r y s t a l i n c o n -t a c t w i t h t h e f o l i a t e d b i o t i t e r i c h g r o u n d m a s s T h e t h r e e s t a g e s o f t h e c r y s t a l h a v e d i f f e r e n t e x t i n c t i o n o r i e n t a t i o n a n d i n t r a z o n a l c o n c e n t r i c z o n a t i o n o f e x t i n c t i o n d i r e c t i o n . S a m p l e c o l l e c -t e d i n w e s t w a l l o f K e e n C r e e k v a l l e y 2 m i l e s n o r t h o f L o n g C r e e k . 5 9 slightly different extinction directions than earlier portions of the crystal. (Figure 5 4 ) The portion of the grain develop-ed during the f i r s t phase of growth is inclusion free, off center with respect to the remaining portions of the crystal, and i s surrounded by an overgrowth with abundant inclusions. A second overgrowth i s inclusion-free and forms the outer bor-der portion of the grain. The outer growth phase is unequally developed around the inner portion. Chiastolite porphyroblasts have concentrations of biotite along their borders as illustrated in Figure 5 6 . Figure 5 6 also shows another textural relationship very common in the Fe-pelite; tendency for garnet and staurolite to develop in the biotite-rich groundmass bordering chiastolite grains. Figure 5 5 , 5 6 , and 5 8 a l l show garnet and/or staurolite developed euhedrally or subhedrally against chiastolite porphyroblasts. Figure 5 8 i s of special interest because i t illustrates the occassional coexistence of staurolite, chiastolite, garnet and biotite in a textural relationship which indicates no obvious disequilibrium textures among the four phases. Biotite-muscovite folia t i o n wraps around chiastolite but is crosscut by both staurolite and garnet. Thompson ( 1 9 5 7 ) shows that ifthe mineral phases garnet, staurolite, andalusite and biotite are considered in the three component system Al-Fe-Mg that only three of these four phases can coexist in equilibrium. Best and Weiss ( 1 9 6 4 , 60 Figure 5 5 : Chiastolite on the l e f t in the photo is rimmed with muscovite and biotite. Stauro-l i t e in upper center of the photo i s in the circum andalusite position typical in the ferrous pelite. Sample collected 2 miles north of Long Creek in the bed of Keen Creek. Figure 5 6 : Staurolite (right) showing inclusion trains continuous with the biotite-muscovite f o l i a -tion enveloping the chiastolite on the l e f t . Sample i s the same as that in Figure 5 5 . Figure 57* Two staurolite porphyroblasts penetrating a chiastolite crystal. Sample collected in Keen Creek 1| miles south of Montezuma Creek. 61 p. 1254) note that the A'FM diagram does not account for the components NagO, CaO and MnO. Thus^if the concentrations of these components in the rock exceed a limit, an extra phase could form to accommodate the excess components above that which can be accepted by the three phases in equilibrium. Ex-ternally controlled humidity may cause extra phases to form by temporarily fluctuating the amount of excess water in the system. Without a knowledge of the zoning in the garnet and other minerals present i t is d i f f i c u l t to state which of these or other factors may account for the extra phases. Figure 59 shows small chiastolite grains developed in meta-pelite immediately adjacent to the margin of Mt. Carlyle stock. The small chiastolites as well as small inclusion-free garnets near the stock contact contrast with the larger chiastolites and subhedral and anhedral garnets farther from the stock mar-gin. The smaller porphyroblasts near the stock possibly repre-sent a distinct generation of crystals but lack of other sup-porting evidence and the small number of thin sections perti-nent to the problem restrict the idea to speculation. Sigmoidal inclusion trains in large chiastolite porphyro-blasts which meet the groundmass at a high angle possibly indi-cate rotational growth with flattening of the crystals previous to development of the present f o l i a t i o n in the rock. Staurolite possibly grew after development of the main mica foliation in 62 Figure 58: From l e f t to right in the photo: stauro-l i t e , chiastolite, garnet and in the upper and lower right side biotite. The four mineral phases seem to be in equilibrium and have sharp boundaries between them. Sample collected in Keen Creek 2 miles north of Long Creek. Figure 59* Small chiastolite porphyroblasts with bio-t i t e and muscovite adjacent to the contact with Mt. Carlyle stock. Sample collected 2 miles north of Long Creek in the north wall of Keen Creek. Figure 60: Large subhedral garnet porphyroblast with opaque inclusions parallel to the biotite-muscovite foliation of the groundmass of the rock. Sample collected 2js miles north of Long Creek in Keen Creek. 63 the rock and i s especially abundant along the edges of chias-t o l i t e crystals. One of the euhedral staurolite crystals that penetrates a chiastolite grain has incorporated the inclusion train of the chiastolite without deflecting the train. The same staurolite crystal crosscuts the mica folia t i o n which has been warped around the chiastolite grain.- This probably indicates an overprinting of the staurolite grain upon the chiastolite grain. Composite staurolite crustals at the end of chiastolite grains have developed within the projected outline of the chias-t o l i t e grains suggesting staurolite nucleation at the site of a pre-existing chiastolite graim;within the former chiastolite boundary. Plagioclase i s very fine grained in the outer portions of the contact metamorphic region but coarsens nearer the stock margin. Five or more suitable grains were determined in each of twelve thin sections from the inner contact aureole and a l l are calcic oligoclase (An22 to 30). A general increase in An content to-ward the stock margin was observed although reversals were noted. Judging the distance to the contact of the stock was complicated in areas where the contact i s gradational. Large muscovite flakes crosscut the dominant biotite-muscovite fo l i a t i o n in the inner part of the contact metamorphic region. These flakes possibly l i e along an incipient strain s l i p clea-vage in tightly crenulated areas near the stock margin. 64 G. SUMMARY OF MICROTEXTURAL INTERPRETATIONS The contact metamorphic minerals are predominantly syn- and post-deformational near the stock margin but are pre- a b r i t t l e deformation i n the northwestern contact region where andalusi-tes have been broken, rotated and altered along microfractures and s t r a i n slipcleavage. The contact metamorphic mineral pha-ses grew i n the following order: c h l o r i t e , b i o t i t e , andalusite, s t a u r o l i t e and garnet, and s i l l i m a n i t e . Andalusite c r y s t a l s with multiple overgrowths and some }along the southern margin of the stock retaining r e l i c t s of an e a r l i e r deformationjare related to i n t r u s i o n of Mt. Carlyle stock and the Nelson Batholith to the south. Late retrograde metamorp-ism has resulted i n s e r i c i t e rims around andalusite, c h l o r i t e knots possibly a f t e r c o r d i e r i t e , and large muscovite flakes cut-t i n g the dominant mica f o l i a t i o n at a high angle. The progression of contact metamorphic mineral assemblages observed i n the metasediments oh' approach to the stock margin may approximately indicate the mineralogical changes during a temperature increase as r e s u l t of emplacement of Mt. Carlyle stock. However, the s c a r c i t y of replacement textures i n the contact metamorphic regions possibly indicates telescoping of the temperature dependent mineral reactions upon rapid heating r e s u l t i n g i n bypassing of intermediate temperature assemblages near the stock margin. 65 H. CONDITIONS OF METAMORPHISM Newton ( 1 9 6 6 a , 1 9 6 6 b ) , using a piston cylinder apparatus and both natural and synthetic starting materials, determined an', A ^ SiO^ phase diagram. This diagram has been superimposed (Fig. 6l) on a composite P,, - T diagram with other experimental " 2 ° curves pertinent to a discussion of the contact metamorphism in Mt. Carlyle area. Kyanite was not observed in the contact aureole of Mt. Carlyle stock. Andalusite i s well developed in the outer aure-ole and f i b r o l i t i c sillimanite occurs nearer the stock indica-ting (Fig. 61) that pressure at the time of metamorphism was probably between 2 . 7 and 6 K b . Newton (1966) indicated limits of uncertainty for the tr i p l e point of approximately 2 . 2 and 5 .5 Kb. Newton*s results indicate that contact metamorphism in the present area took place at temperatures of at least 400° c and up to approximately 650° c. Richardson, Bell, and Gilbert (1967) obtained results which agree well with those of Newton and found that varying water content in the experimental runs had l i t t l e effect on the A 1 2 S 1 0 ^ transition reactions. The limits of uncertainty of both Richardson and Newton and the variation in other published t r i p l e point positions affords only general conclusions as to temperature and pressure based on AlgSlO^ transitions. Schreyer and Yoder (1964) using a variety of natural and 66 synthetic materials, produced a stability diagram for Mg-cordierite under hydrous and anhydrous conditions. The curve for the lower stability limit of Mg-cordietite under hydrous con-ditions appears in Figure 6 1 . Schreyer (1964) noted that under anhydrous conditions the stab i l i t y f i e l d for Mg-cordierite i s much more restricted below the melting curve of granite. S chreyer and Yoder (1964) have determined a melting curve for granite based on previous work by Tuttle and Bowen (1958), Yoder and T i l l e y ( 1 9 6 2 ) , and Luth, Jahns, and Tuttle ( 1 9 6 3 ) . This curve represents a high temperature limit under hydrous conditions for contact metamorphism and is reproduced in Fig-ure 6 1 . This curve i s displaced toward higher temperatures un-der anhydrous conditions. Figure 61 indicates that the Mg-cordierite curve intersects the melting curve for granite at 7 K b . indicating a maximum pressure under which cordierite would be li k e l y to form in meta-morphic rocks. Field occurances of staurolite (Read, 1952) (Zwart, 1962) indicate that i t i s a common mineral i n metamorphic facies ser-ies containing andalusite, cordierite and garnet. The pressure-temperature, conditions giving rise to such assemblages are typi-cally intermediate between contact and regional metamorphism. Figure 61 (dotted curves) includes a stability f i e l d for staurolite (Hietanen, 1967) inferred from f i e l d relations 6 7 rather than based on experimental data. Hietanen ( 1 9 6 7 ) in-cluded a different Al 2SiO^ phase diagram than that in Figure 6 1 . The staurolite stability f i e l d in Hietanen fs compositeP-T dia-gram f e l l well within the sta b i l i t y f i e l d of andalusite and slightly within that of sillimanite near the tr i p l e point. Hietanen*s st a b i l i t y f i e l d i s included here only to give a general idea of a postulated staurolite range and to indicate that the occurrance of andalusite with staurolite possibly i n -dicates pressures near the upper pressure limit of andalusite. Richardson ( 1 9 6 8 ) investigated the relations in the system Fe-Al-Si-O-H between Fe-staurolite, Fe-cordierite, almandine, Fe-chloritoid, quartz and sillimanite. Reaction curves for the reactions: Fe-staurolite + quartz-±; Fe-cordierite + sillimanite + H^ O Fe-chloritoid + sillimanite ±? Fe-staurolite + quartz + H^ O are indicated by dashed lines on the P^  Q-T diagram of f i g . 6 1 . As shown in figure 6 1 the st a b i l i t y f i e l d for Fe-staurolite + quartz spans a temperature range of approximately 1 5 0 ° and i t s lower pressure limit in rocks where cordierite forms i s approx-imately l j Kb. Where cordierite has a higher ^/Fe ration than that considered by Richardson }the lower sta b i l i t y limit of staurolite rises as does the upper limit of cordierite s t a b i l i t y . Richardson's work indicates that in ferrous-pelite of the pre-sent study, where no cordierite was observed, minimum f l u i d 6 8 1 2 3 4 5 6 7 T °c x 100 • 6 1 P H^Q_T diagram with s t a b i l i t y curves pert inent to rocks i n the contact metamorphic aureole of M t . C a r l y l e stock 69 pressure possibly was 3jKb. and almost certainly exceeded 1^ Kb. with minimum temperature of at least 500° c. Ganguly (1968).. suggests that the sta b i l i t y f i e l d of stauro-l i t e may be highly dependent on oxygen fugacity even in rocks having the same bulk composition. The isograd for staurolite may actually cut across isotherms. The effects of extra com-ponents such as Cao and Mno in a system may cause the stability limits of staurolite to be shifted significantly. Evans (1965) determined an equilibrium curve for the reac-tion Muscovite + quartz K-feldspar + AL^SiO^ + H20. This curve i s reproduced in Figure 61 and is applicable to the highest temperature part of the contact aureole of Mt.Carlyle stock. The reaction curve for muscovite meets the minimum mel-ting curve for granite at approximately 3s Kb. Above 3s Kb. the onset of anatexis occurrs at a lower temperature than that at which the muscovite breakdown reaction w i l l proceed to the right. Summary. Pressures in the rocks bordering Mt. Carlyle stock during contact metamorphism were probably in the range 2\ - 7Kb. P^ Q and temperatures probably reached approximately 650° c. Assuming hydrostatic pressure ;this range corresponds to 23,000 to 7^,000 feet of burial beneath the surface of the earth and mineralogic assemblages just discussed indicate that the true 7 0 Pj| Q was probably nearer the lower depth estimate. The Q may have been higher during contact metamorphism than P^ Q to be expected as a result of burial, since stress arising from emplacement of Mt. Carlyle stock and contact metamorphic dehy-dration reactions possibly increased the f l u i d pressure some-ivhat. The area shaded in Figure 61 i s a graphical estimate of Pg Q -T conditions for the present contact metamorphic area. In constructing a diagram such as Figure 61 i t is apparent that the results of many previous workers are incorporated. The estimate of P™ n -T range for the contact aureole of the stock depends on the particular curves selected and this e s t i -mate would be shifted significantly i f experimental curves of different workers were employed, figure £i gives only a quali-tative idea of conditions of metamorphism in the present area. 71 IV. CONCLUSIONS Emplacement of Mt. Carlyle stock was accomplished through variable mechanisms as evidenced by varying contact effects on surrounding metasediment of the Slocan Group. The eastern stock margin i s gradational across a 250 foot wide contact zone displaying gradations between p e l i t i c country rock and granitic rock suggesting partial assimilation of country rock. Northern stock margins contain large limestone roof pen-dants and many inclusions of country rock. Stock margins crosscut the trend of bedding i n calcareous units; a feature unique to this border of the stock. Northern marginal parts of the stock possibly assimilated some of the calcareous rock, as suggested by crosscutting contact relations and decreasing Ca content toward the south in the stock. Metasediment along northwestern and western stock margins is characterized by increasing intensity and frequency of large crumples, crenulation along s l i p cleavages, intrusive dikes, and faults. Altered contact metamorphic porphyroblasts have been af-fected by strain s l i p crenulation suggesting the stock has possibly imposed stresses on the country rock after the main thermal event in the contact aureole. In a septum of metasediment between the southern margin of 72 Mt. Carlyle stock and the Nelson Batholith, a mica folia t i o n is prominent parallel to margins of both bodies. In the wes-tern part of this septum, tight folds marginal to the Nelson Batholith have been deformed and tightened. These tightened folds are crosscut by a weak folia t i o n parallel to the margin of Mt. Carlyle stock and by intersecting fracture cleavage that i s possibly related to stress imposed by intrusion of the stock. Near Mt. Carlyle stock, in the western part of the sep-tum, minor folds are very tight, sheared out, and discontinu-ous. These structures suggest that emplacement of the stock occurred after emplacement of the Nelson Batholith. This suggestion, i s supported by evidence of recrystallization with-in large chiastolite porphyroblasts.in the western part of the metasedimentary septum. The porphyroblasts contain elongate, arcuate quartz inclusions that possibly are r e l i c t s of a de-formation prior to f i n a l crystallization of the porphyroblasts. Microtexture"3 in Fe pelite along the eastern stock margin i n -dicate that staurolite and garnet grew after development of biotite f o l i a t i o n . Fabric of inclusions in staurolite and gar-net i s continuous with similar fabric in the groundmass of the rock. Ocassionally inclusion trains outline earlier cre-nulations that have been incorporated into growing staurolite and garnet crystals. Groundmass fol i a t i o n commonly warps around chiastolite porphyroblasts although foliated biotite 73 layers are terminated against staurolite and garnet por-phyroblasts. Sillimanite forms from muscovite, biotite, and andalusite in various parts of the contact aureole. In Mg pelite, cordierite i s poikiloblastic and probably grew after the main biotite f o l i a t i o n was developed. The microtextures suggest the following approximate se-quence of mineral development although no single outcrop con-tains a l l of the mineral phases: biotite, andalusite, stauro-l i t e and garnet, cordierite and sillimanite. Relict inclusion trains indicate that deformation of the rock began before development of contact metamorphic minerals. Late strain s l i p cleavage associated with retrograde metamor-phism has disturbed older andalusite porphyroblasts indicating that deformation outlasted the main contact metamorphic re-crystallization . The contact metamorphic aureole surrounding the stock sug-gests that the stock was a source of heat. Thermal effects and crosscutting relationships with the surrounding Slocan Group metasediment suggest that Mt. Carlyle stock i s , at least in part, of magmatic origin. Recent experimental work on P H Q -T s t a b i l i t i e s of the meta-morphic minerals in the contact aureole allow a general e s t i -mate of conditions prevailing during emplacement of Mt.Carlyle stock. 74 The high temperature limit of metamorphism under hydrous conditions i s the minimum melting curve of granite. The absence of kyanite in the present area possibly limits P H Q to 6|Kb. or less. The occurrence of sillimanite in high S temperature parts of the aureole possibly indicate a minimum P H 0 o f 2 ^ K b * T n i s l ° w e r p H 0 l i m i t a S r e e s w i t h a l|Kb. 2 2 lower limit of Fe-staurolite in the presence of cordierite and a 3|Kb. limit where cordierite i s absent. Conditions i n the contact aureole of Mt. Carlyle stock during thermal metamorphism were possibly i n the p H 2 G r a n S e o f 2|Kb. to 7Kb. and in the temperature range from 400o c to 650° c. These figures are at best approximations of the true conditions. 75 V. REFERENCES CITED Best, M.G., Weiss, L.E., 1966, Mineralogical relations i n some P e l i t i c Hornfelses from the Southern Sierra Nevada, C a l i f o r n i a : Amer. Min., vol.49, p.1240-1266. Cairnes, C.E., 1934, Slocan Mining Camp, B.C.: Geol. Surv.Canada, Mem. 173. Compton, R.R., 1955, Trondhjemite Batholith Near Bidwell Bar, C a l . : G.S.A. B u l l . , vol.66, pp. .'9^ 44. — , I960, .Contact Metamorphism i n Santa Rosa Range, Nevada: G.S.A. B u l l . , v o l . 71, pp. 1333-1416. Ganguly,.J., 1968, Analysis of the s t a b i l i t i e s of c h l o r i -t o i d and -staurolite and some E q u i l i b r i a i n the sys-tem FeO-Al-O^-SiOp-rLO-O-: A.J.S., v o l . 266, p.297-2<^ 8 <- 5 <~ £ <~ Green, J.C.,1963, High Level Metamorphism of P e l i t i c Rocks i n Northern New Hampshire: Amer.Min., vol.4#, p.991-1023. Hedley, M.S., 1952, Geology and ore Deposits of the Sandon Area, Slocan Mining Camp, B.C.: B.C.Dept.Mines, B u l l . 29. Hietanen, A., 1967, On the Facies Series i n Various Types of Metamorphism: Journ.of Geol., vol.75, no. 2. Irwin, A.B., 1951, Mapping Complex Folds i n the Slocan Series, B.C.: Trans. Can.Inst.Mining Met., v o l . 54, pp. 494-501. , 1952, Discussion on Mapping Complex Folds i n the Slocan Series, B.C.: Trans. Can.Inst.Mining Met., v o l . 55, pp. 242-244. L i t t l e , H.W., I960, Nelson Map-Area, West Half, B.C.; Geol.Surv.Canada, Mem.308. Miyashiro, A., 1957, C o r d i e r i t e - I n d i a l i t e Relations: Amer.J. S c i . , v o l . 255, p.43-62. 76 Newton, R.C., 1 9 6 6 a , K y - s i l l equil, at 7 5 0 ° c: Science, v o l . 151, p. 1222-1225. , 1966b, Kyanite-andalusite equil. from 700° to 800° c: Science, v o l . 1 5 3 , p. 1 7 0 - 1 9 2 . Pitcher, W.S., R ead, H.H., 1963, Contact Metamorphism i n Relation to Manner of Emplacement of the Granites of Donegal, Ireland: Journ. Geol., v o l . 71, no.3, 1963. Read, H.H., 1952, Metamorphism and Migraatization i n the Ythan Valley, Aberdeenshire: Edinburgh! Geol.Sacv. Trans., v o l . 15 (Campbell Volume), p.2 6 5 - 2 7 9 . Richardson, S.W., 1968, The S t a b i l i t y of Fe-Staurolite and Quartz: Carnegie Inst .Wash., Yearbook 67, pp.3 9 7 - 4 0 2 . , B e l l , P.M. and G i l b e r t , M.C., 1968, The Aluminium S i l i c a t e s : Carnegie Inst. Wash., Yearbook 67, p . 3 9 2 - 3 9 7 . Schreyer, W., Yoder, H.S.Jr., 1 9 6 4 , The System MgCordierite-H_0 and related rocks: N.Jb.Miner.Abh. vol.101, # 3 , pp. 2 7 1 - 3 4 2 . S i n c l a i r , A..J.? and Libby, W.G., 1967, D i s t r i b u t i o n of Major Minerals i n a Stock of Nelson Plutonic Rock, South Central B.C.: Abs., Can.Min., v o l . 9 , p. 3 0 8 . Thompson, J.B., J r . , 1957, Graphical Analysis of Mineral Assemblages i n P e l i t i c Schists: Amer. Min., v o l . 42, pp.842-853. Yoder, H.S., 1955, Role of Water i n Metamorphism: GSA, Spec. P*£pe;r 62, 1955, pp. 505-524-Zwart, H.J., 1958, Regional Metamorphism and Related Grani-zation i n the Val l e de Arau (Central Pyrenees): Geologie en Mijnbouw, new.ser., v o l . 20, no. 1, pp.18-30. • / 49 45 

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