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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.Sc,  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 o f Geology  We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e 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 an  this  thesis  in partial  f u l f i l m e n t of the requirements f o r  advanced degree a t the U n i v e r s i t y o f B r i t i s h  the  Library  I further for  shall  make i t f r e e l y  agree that  permission  s c h o l a r l y p u r p o s e s may  by  his representatives.  of  this  thesis  available  for financial  gain  Geology  Date  September27,  Columbia  1968  that  I agree  that  and-Study.  copying of this  be g r a n t e d b y t h e Head o f my  It i s understood  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, Canada  f o r reference  f o r extensive  written-permission.  Department o f  Columbia,  thesis  Department o r  copying or p u b l i c a t i o 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  i  ABSTRACT The d e f o r m e d T r i a s s i c sisting  of  argillite,  S l o c a n Group sedimentary  limestone,  r e g i o n a l l y metamorphosed,  folded,  and q u a r t z i t e ,  in  stock,  aerial  extent,  S l o c a n Group  was  morphic a u r e o l e  emplaced by f o r c e f u l  Mt.  stock  is  effects  on  meta-  andalusite,  stauro-  proximity to  and s t r u c t u r a l  Group m e t a s e d i m e n t s the  enveloped i n a contact garnet  and s i l l i m a n i t e d e v e l o p e d i n  increasing order of Petrographic  miles  i n t r u s i o n and  d i s c e r n e d from the contact  with b i o t i t e ,  cordierite,  Batholith to  (Jurassic).  metasediments.  The m a r g i n o f t h e  lite,  been  a c o m p o s i t i o n a l l y z o n e d b o d y 21 s q u a r e  p a s s i v e a s s i m i l a t i o n as the  have  con-  and i n t r u d e d and t h e r m a l l y  metamorphosed b y N e l s o n P l u t o n i c R o c k s Carlyle  rocks  the  stock  evidence  the  approximate  margin.  i n a septum o f  between M t . C a r l y l e s t o c k  south suggests that  and  and t h e  stock  Slocan Nelson  postdates  the  batholith. Experimental data semblages i n the that  contact  temperatures  b e t w e e n 2\  up t o  of f a c i e s  conditions.  aureole  the metamorphic m i n e r a l of Mt. C a r l y l e stock  a p p r o x i m a t e l y 6 5 0 ° c and  and 7Kb. p r e v a i l e d d u r i n g c o n t a c t  metamorphism i n t h e istic  pertinent to  contact  series  regions  of the  as-  indicate  pressures  m e t a a o r p h i s m . The  stock  is  i n t e r m e d i a t e between c o n t a c t  characterand r e g i o n a l  ii:. -TABLE OF CONTENTS I.  INTRODUCTION  1  A.  1 1 1 2 2 4 5 5 7 9  GENERAL INTRODUCTION al Scope b) Purpose c) L c a t i o n and Topography d) P r e v i o u s Work e) Acknowledgements B. GENERAL GEOLOGY ¥ ) S l o c a n Group b) N e l s o n P l u t o n i c Rocks c) Mt. C a r l y l e Stock STRUCTURAL ELEMENTS IN THE CONTACT REGION IN MT. CARLYLE STOCK A. PRIMARY STRUCTURES B. SECONDARY STRUCTURES a l Area I b) Area I I c) Area I I I d) Area IV C. TEMPORAL RELATIONS BETWEEN THE NELSON BATHOLITH AND MT. CARLYLE STOCK 0  II.  D. III.  MODE OF EMPLACEMENT"OF MT« CARLYLE STOCK  METAMORPHISM  13 13 16 18 24 28 31 39 40 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  iii  ILLUSTRATIONS Figure  Page  1  Index Map f o r t h e i e l d Area  2  Contact Creek  3  F  of Mt. C a r l y l e Stock i n Montezuma 11  3  Zoned K - f e l d s p a r p h e n o c r y s t s  4  Large t a l u s b l o c k s o f p o r p h y r i t i c monzonite  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 s t o c k  12  6  F o l i a t e d b o r d e r phase o f M t . C a r l y l e s t o c k  12  7  C r o s s b e d d i n g i n q u a r t z i t e from near southwest margin o f M t . C a r l y l e s t o c k  15  £  Original layering i n schist  15  9  Original layering i n p h y l l i t e  15  Map o f M t . C a r l y l e s t o c k 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 o f the s t o c k  17  Screens o f s c h i s t i n t e r m i x e d w i t h g r a n i t i c r o c k o f b o r d e r o f Mt. C a r l y l e s t o c k  19  12  Screens o f s c h i s t and g n e i s s a t b o r d e r o f Mt. C a r l y l e stock  19  13  Screen o f metasediment i n g r a n i t i c r o c k  19  14 and 15  T h i n l y l a m i n a t e d and f o l d e d metasediment i n screens i n g r a n i t i c rock  22  16  G n e i s s f r o m margin o f M t . C a r l y l e s t o c k  22  G n e i s s 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  P e g m a t i t e i n s c h i s t and g n e i s s  23  10  11  17 1$ and 19  11 quartz  11  iv  Figure  Page  20  L a r g e r o o f pendant i n M t . C a r l y l e s t o c k  26  21  Roof pendant i n Mt. C a r l y l e s t o c k  26  T i g h t f o l d i n g i n l i m e s t o n e r o o f pendant i n Mt. " C a r l y l e s t o c k  27  22 and "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 phyllite  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 27  Intersecting crenulations i n foliated schist F o l i a t e d m e t a p e l i t e c o n t a i n i n g a n d a l u s i t e and garnet porphyroblasts  30 33  2S  F o l i a t i o n i n metapelite containing large andalusite porphyroblasts  33  Original layering sub-parallel to foliation i n p e l i t i c schist  33  M i n o r f o l d s i n i n t e r b e d d e d p e l i t e and q u a r t z i t e beds  34  32  M i n o r f o l d s w i t h a s m a l l 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 schist w i t h large andalusite p o r p h y r o b l a s t s 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 c l e a v a g e and s m a l l 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 p a r t of t h e c r y s t a l  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 inclusions  36  29 and 30 31  36 and 37 3#  T h i n bedded impure l i m e s t o n e  quartz  45  V  Figure 39 40  Page F i b r o l i t e - b i o t i t e mats adjacent to a pegmatite v e i n i n t h i n l y interbedded q u a r t z i t e and s c h i s t  45  F i b r o l i t e bundles w i t h b i o t i t e and some museov i t e i n a q u a r t z - f e l d s p a r groundmass  45  41  F i b r o l i t e w i t h b i o t i t e rimming quartz and spar g r a i n s  42  C h i a s t o l i t e p o r p h y r o b l a s t s i n random o r i e n t a t i o n w i t h i n a f o l i a t i o n plane i n m e t a p e l i t e  47  C h i a s t o l i t e p o r p h y r o b l a s t s w i t h 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 covite-quartz-opaque m a t r i x  46  C o r d i e r i t e knots i n s c h i s t appear as brown spots on a weathered s u r f a c e  51  C o r d i e r i t e porphyroblasts i l l u s t r a t i n g b l a s t i c texture  51  43  47 and 4S 49  feld!  mus-  51  poikilo-  Table of occurrences o f common boundaries 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 of Mt. C a r l y l e stock  53  Map of Mt. C a r l y l e stock and i n f e r r e d i s o g r a d s i n the c o n t a c t metamorphic aureole  54  M i n e r a l assemblages and p o s s i b l e m i n e r a l r e a c t i o n s i n p e l i t i c metasediment from the contact aureole of Mt. C a r l y l e stock  55  51  A'FM diagrams f o r contact metamorphic m i n e r a l assemblages i n the a u r e o l e of M t . C a r l y l e stock  56  52  Subhedral s t a u r o l i t e p o r p h y r o b l a s t and euhedral garnet p o r p h y r o b l a s t i n a b i o t i t e f o l i a t i o n  50 50b  VI  Figure 53 54  Page 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 inclusion trains  retaining  5#  A n d a l u s i t e p o r p h y r o b l a s t t h a t formed d u r i n g t h r e e s t a g e s o f growth  5#  55  C h i a s t o l i t e rimmed by m u s c o v i t e , b i o t i t e , and staurolite  60  56  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 a t edge o f c h i a s t o l i t e porphyroblast  60  57  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 p e n e t r a t i n g a chiastolite crystal  60  58  S t a u r o l i t e , c h i a s t o l i t e , g a r n e t and b i o t i t e w i t h common b o r d e r s  62  Small c h i a s t o l i t e porphyroblasts with b i o t i t e and m u s c o v i t e  62  Large s u b h e d r a l garnet p o r p h y r o b l a s t w i t h opaque i n c l u s i o n s  62  P I T Q-T diagram w i t h s t a b i l i t y c u r v e s p e r t i n e n t 2 t o r o c k s i n the c o n t a c t metamorphic a u r e o l e o f Mt. C a r l y l e s t o c k  68  59 60 61  PLATES Plate 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 f e e t .  Mapping was carried  out during a nine week period i n the summer of 1967. Twohundred-fifty  hand specimens were collected from the  Slocan Group metasediments, Mt. Carlyle stock and associated dikes and plugs. Seventy t h i n sections were prepared and studied. Other laboratory study included X-ray d i f f r a c t i o n i d e n t i f i c a t i o n 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 s t r u c t u r a l and mineralogical e f f e c t s of the stock upon the enclosing sedimentary rocks.  An attempt i s made to determine the sequence  of emplacement of the stock and the b a t h o l i t h to the south.  2  c) Location and Topography : Mt. Carlyle stock, i n 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) i n the Selkirk Range. The area i s cut by a number of U-shaped, steep-walled v a l leys which head i n talus covered cirques as shown i n Figure 2. Outcrop i n the main streams i s extremely scarce and the best exposures were found i n tributary channels.  Ridges are sparse-  l y 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 i n 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.  lead into the area to old s i l v e r mines within  Two  trails  Mt.Carlyle  stock, one from Cody, the other from the Keen Creek road. d) Previous Work Cairnes (1934) studied the Slocan Mining Camp.  He c l a s s i -  f i e d the contacts of the Nelson Plutonic Rocks as gradational to intrusive i n nature and described roof pendants and the surrounding Slocan Group.  S i n c l a i r and Libby (1967) studied  4  the mineral d i s t r i b u t i o n i n  Mt.Carlyle stock using trend  surface analysis. Irwin (1951) described the f o l d i n g i n 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 f o l d .  Hyndman (1968) delineated  three stages of f o l d i n g i n 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 e a r l i e r  work i n 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. S i n c l a i r of the University of B r i t i s h Columbia f o r f i n a n c i a l support of f i e l d and laboratory investigation through a N.R.C. grant. Libby, Dr. S i n c l a i r and Dr. J.V. Ross provided  Dr. W.G.  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 h i s mine cabin as a f i e l d base camp.  5  B) a)  GENERAL GEOLOGY  Slocan Group  Slocan Group i s composed of argillaceous sedimentary rocks with some interbedded impure quartzite and limestone. In the. area under study, t h i s group has predominantly steeply dipping f o l i a t i o n which i s nearly p a r a l l e l to bedding where both bedding and tectonic f o l i a t i o n Slocan Group i s thought  were observed.  (Cairnes, 1934)  The  to l i e disconformably  above the Kaslo Greenstones which are exposed to the northeast . Slate and p h y l l i t e of the Slocan Group are black to greygreen regionally metamorphosed a r g i l l i t e . . grey or black and near the contact with  Quartzite i s dark Mt. Carlyle stock  contains i r o n oxides, b i o t i t e , and f i b r o l i t e .  Limestone i s  coarsely c r y s t a l l i n e , grey, with l e n t i c u l a r beds ranging from a few inches to tens of feet i n thickness.  In the contact  metamorphic aureole laminae of argillaceous and material delineate minor f o l d s .  quartzose  Near the igneous contact the  limestone becomes coarser grained and paler i n color. Alternating pale to dark green layers i n slates and phyll i t e s are a f r a c t i o n of an inch t h i c k .  With increasing pro-  ximity to the igneous contact t h i s compositional layering becomes more marked and the color changes to alternating l i g h t grey and pinkish brown accompanying the development of andal u s i t e , b i o t i t e and other metamorphic minerals.  6  Gairnes sediments sitional  to  t h e west  stresses  Sandon a r e a was t h e  set  up b y t h e  s o u t h and e a s t except  plunge at to  the  stock  structures  o f recumbent,  Hyndman  of the  least  Slocan  in part,  axes are  almost  hori-  Sandon where t h e y  northwest or  southeast.  Near  :. M t . C a r l y l e  t h e b e d s have b e e n d o w n b u c k l e d and steepen.  i n t h e Howson C r e e k B a s i n t o d e l i n e a t e near-isoclinal folds  These f o l d s  a  w i t h axes p l u n g i n g  t r e n d N45°W.  (196S) d i s t i n g u i s h e d t h r e e p h a s e s o f f o l d i n g i n t h e of the present  phase o f d e f o r m a t i o n i n v o l v e d  area  intense  of  study.  second phase formed n e a r l y u p r i g h t f o l d s c l e a v a g e e x p r e s s e d as The t h i r d  granitic  plutons  and a s t r a i n  c r e n u l a t i o n of the f i r s t  d e f o r m a t i o n was due t o that  f o l d e d the  The  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.  ous  of  Nelson B a t h o l i t h  n e a r t h e town o f  axes  S l o c a n Group northwest  sity.  depo-  (1951) made use o f p r i m a r y s e d i m e n t a r y f e a t u r e s and  t h a n 30°.  first  at  N e l s o n B a t h o l i t h and  o f minor f o l d  secondary series  recumbent,  Major f o l d  s m a l l angles to the  Hedley noticed that  Irwin  less  i n the area  o f the  result,  emplacement  of the area.  contact  plunges  a shallow water  (1952) s t a t e d t h a t t h e l a r g e ,  i n the  zontal  and p o s t u l a t e d  environment.  Hedley fold  (1934) p l a c e d t h e s o u r c e o f t h e S l o c a n Group  The slip  phase  schisto-  intrusion of  Cretace-  surrounding country rocks.  7  Irwin (1951) estimated the Slocan Group to be 3 7 , 0 0 0 feet thick based on the f o l d i n g observed i n the Howson Creek Basin and adjoining areas.  Cairhes ( i n Irwin, 1 9 5 2 ) objected to  t h i s estimate of thickness and considered a thickness of 7 , 0 0 0 feet to be a more reasonable f i g u r e .  Hedley (1952)  estimated  a thickness of about 2 0 , 0 0 0 feet f o r the Slocan Group. The Slocan Group i s cut by numerous f a u l t s of small d i s placement and these are e s p e c i a l l y common near plutonic rocks. Cairnes ( 1 9 3 4 ) 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 l a t t e r body. b)  Nelson Plutonic Rocks  Nelson Plutonic Rocks are composed of granite, quartz d i o r i t e , monzonite and syenite i n order of decreasing abundance (Little, i 9 6 0 ) . nal.  Contact between these rock types i s gradatio-  K-feldspar phenocrysts are common i n the granite and de-  crease i n size and number nearer the borders.  Quartz content  decreases, plagioclase and hornblende become more abundant, and the g r a n i t i c rock tends to become f o l i a t e d with increasing proximity t o 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 g r a n i t i c to granodioritic composition. The porphyritic granite member i s gradationaliy zoned toward the borders of the batholith to granodiorite and quartz d i o rite. The V a l h a l l a g r a n i t i c complex to the west displays varied contacts with the Nelson porphyritic granite: i n t e r f i n g e r i n g , cutting, gradational ( l i t t l e ,  i960).  L i t t l e (I960) suggest-two modes of emplacement f o r rocks included i n a broad d e f i n i t i o n of Nelson Batholith: metasomatism of the pre-existing rocks based on the gradational contact between paragneiss and granite; magmatic i n j e c t i o n based on crosscutting r e l a t i o n s between contact phases of the granite 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 f o r emplacement of Nelson Plutonic Rocks.  Much of t h i s complexity has arisen  from confusion i n delimiting the geographic extent of the Nelson Batholith.  Reesor (1965) r e s t r i c t e d the term Nelson  Batholith to g r a n i t i c 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 o r i g i n .  (Reesor, 1 9 6 5 ; 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 i n color than Nelson Plutonic Rocks to the south.  A p a r t i a l rim of  granodiorite encloses the quartz monzonite core and t h i s grades l o c a l l y into a d i o r i t e border phase.  The quartz mon-  zonite contains zones of K-feldspar phenocrysts up to two inches i n length ( F i g . 3 and 4). . Roof pendants i n the northern part of the stock lend an i r r e g u l a r appearance to the stock. i n length) occur throughout  Xenoliths (up to one foot  the stock but are most abundant  i n the northerly portions ( F i g . 5 ) . The stock contact i s gradational i n places with screens and inclusions of the surrounding metasediment within the g r a n i t i c 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 , M t . C a r l y l e stock and the surrounding metasediment.  Small plugs of d i o r i t e and quartz d i o r i t e intrude  the contact metamorphic aureole surrounding the stock. The stock i s weakly f o l i a t e d due to preferred orientation  o f hornblende and b i o t i t e . near the margin o f the s t o c k  \  T h i s f o l i a t i o n i s pronounced (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 i n the lower l e f t corner and the contact between Mt. Carlyle stock and Slocan group metasediments appears above the l i n e of dwarf trees on the west side of Mt. Holmes i n 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 i n c l u s i o n s . Sample collected east of Mt. C a r l y l e . Scale i n 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 b i o t i t e r i c h inclusions i n the granodioritic phase of Mt. Carlyle stock. The sample i s weakly f o l i a t e d parall e l to the surface showing i n the photo. Sample collected on the ridge forming the West wall of the head of the Montezuma Creek Valley. Scale i n 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 i n inches.  13  I I . STRUCTURAL ELEMENTS IN THE CONTACT REGION OF ' MT.- CARLYLE STOCK A) PRIMARY STRUCTURES Primary features recognized i n the Slocan Group are crossbedding, compositional layering and graded bedding. (1951)  Irwin  also reported r i p p l e marks but none were seen by the  author. Figure 7 shows crossbedding i n quartzite collected near the southwest margin of of Mt.Heyland.  . Mt.Carlyle stock one mile north  Graded bedding i n interbedded quartzite and  semischist is- common i n the same area.  Graded bedding and  crossbedding are recognizable at a l l grades of metamorphism,. The s ense of gradation i n grain size i s reversed r e s u l t i n g from development of porphyroblasts during metamorphic recrystallization.  In the o r i g i n a l l y fine-grained argillaceous  layers large andalusite c r y s t a l s have grown and the o r i g i n a l l y coarser, quartz r i c h layers have r e c r y s t a l l i z e d to s i l i c e o u s hornfels composed of quartz, plagioclase, b i o t i t e , f i b r o l i t e and muscovite i n decreasing order of abuncance. O r i g i n a l sedimentary layering has become emphasized by metamorphic r e c r y s t a l l i z a t i o n .  Bedding i s commonly p a r a l l e l  or sub-parallel to a dominant mica f o l i a t i o n i n the o r i g i n a l l y clay r i c h layers,  figure g shows t h i n interbeds of anda-  14  lusite-bearing and more quartz r i c h layers i n a p h y l l i t e . Figure 9 shows o r i g i n a l layering p a r a l l e l to a strong, crenulated  foliation i n a phyllite.  15  Figure  7  : Crossbedding i n quartzite from the South facing slope of the ridge 1 mile northwest of Mt. Heyland. Tops of beds are toward the bottom of the photo. Scale i n inches.  Figure  £:  O r i g i n a l layering i n s c h i s t . The dark porphyroblasts are andalusite. Sample collected near the stock margin south of the lower portion of Montezuma Creek. Scale i n inches.  Figure  9:  O r i g i n a l layering i n p h y l l i t e . Note f o l i a t i o n due to mica orientation p a r a l l e l to the layering and crenulation of t h i s f o l i a t i o n i n the uncut surface. Curved l i n e s on cut rock face are saw marks. Sample collected at the stock margin near the confluence of Long and Keen Creeks. Scale i n inches.  16 B. SECONDARY STRUCTURES Secondary structures associated with the mode of emplacement of the stock, are best described by t r e a t i n g four areas along the stock margin seperately.  These four areas are i n -  dicated on Figure 10 and w i l l be described s t a r t i n g 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 f o r separating the contact region into four areas are twofold:  the d i f f e r i n g sharpness of the contact between  the Slocan Group and the stock; the varying degree of development of f o l i a t i o n , kinks, f a u l t s and other features i n the contact regions.  F I G . 10  Map o f M t . C a r l y l e s t o c k 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 c o n t a c t r e g i o n o f the s t o c k  18  a) Area I In the f i r s t area f o l i a t e d , but otherwise r e l a t i v e l y homogeneous g r a n i t i c rock grades through 100 to 250 feet of interlayered g r a n i t i c and schistose rock to metasediment essentia l l y free of g r a n i t i c layers.  This gradational contact can  be divided into four belts p a r a l l e l to the stock margin and each displays gradational i n t e r n a l r e l a t i o n s , 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 i n t h i s area i s hornblende and b i o t i t e quartz d i o r i t e with K-feldspar phenocrysts simil a r to those found i n varying numbers i n the i n t e r i o r of the stock.  The quartz d i o r i t e commonly i s f o l i a t e d due to paral-  l e l alignment of hornblende and b i o t i t e .  Figure 6 i s a photo-  graph of t h i s igneous border phase. Quartz d i o r i t e grades to a belt of oriented screens of schist within granodioritic material.  Metasedimentary  screens  are oriented v e r t i c a l or dip steeply outward from the stock. The rocks i n t h i s belt d i f f e r from the gneiss b e l t , described next, i n the scale at which the schistose and g r a n i t i c material i s interlayered.  Screens of schist are one-half to three feet  thick becoming gneissic at t h e i r margins where they grade into g r a n i t i c material. screens.  Figures 11, 12 and 13 show shistose  19 Figure  11: Screens of schist intermixed with g r a n i t i c rock. These rocks are t r a n s i t i o n a l between t y p i c a l screen development and gneiss. Photo taken near the confluence of Long and Keen Creeks. Scale given by hammer, pen and n i c k e l .  Figure  12: Irregular screens of schist and gneiss from the same l o c a l i t y as Figure 11. The screens trending from lower l e f t to upper right p a r a l l e l the stock margin. Scale given by hammer, pen and n i c k e l .  Figure  13: Screen of metasediment i n g r a n i t i c rock. Note vein i n center of photo that pinches and swells i n the metasediment. Photo taken at stock margin east and south of Mt. C a r l y l e . Scale given by hammer, n i c k e l and pen.  20  Screens have tightened minor folds within the schistose f o l i a t i o n which i s roughly p a r a l l e l 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 t h i n b i o t i t i c and quartzofeldspathic laminae. The screen b e l t grades outward from the stock into a belt of gneiss consisting of thin i n t e r l a y e r s of metasediment and quartzofeldspathic rock.  Within t h i s belt b i o t i t e has been  p a r t i a l l y isolated i n ring shaped and planar concentrations surrounding and i n t e r f i n g e r i n g with fine-grained quartzofeldspathic 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 f o l d s with a x i a l planes p a r a l l e l to the f o l i a t i o n .  This f o l i a t i o n  p a r a l l e l s the steeply dipping contact region and the gneissic f o l i a t i o n i n the contact belts described above.  F o l i a t i o n of  the schists i s gently warped around cuspate apophys.e. s of the stock. A crenulation i n the f o l i a t i o n just described i s developed l o c a l l y along the eastern margin of Mt. Carlyle stock (Fig. 26) but i s much more pronounced along the western margin described below. Slocan Group schists i n Area 1 are l o c a l l y cut by  21  pegmatitic material i n the outer parts of the gradational contact. 19.  This phenomenon i s i l l u s t r a t e d i n Figures Id and  22  Figures 14 and 15:  Figure  16:  Folds i n screens at the stock margin with t h i n lamination of quartzofeldspathic and b i o t i t i c material. Laminations metamorphic segregation possibly along o r i g i n a l bedding i n the s c h i s t . Scale i s i n inches.  Gneiss composed of t h i n , highly i r r e g u l a r bands of dark grey schistose rock and l i g h t colored granodioritic material. Sample collected at the stock margin where i t crosses the ridge separating Keen and Montezuma Creek V a l l e y s . Scale i n inches.  23 Figure  17*  Figure 18 and 19*  of Gneiss with r i n g - l i k e concentration biotite. collected i n the stock contact region from the same area as Figure 16. Curved l i n e s on rock surface are saw marks. Scale i n inches.  1  Pegmatite i n schist and gneiss from the outer part of gradational contact of the Mt. Carlyle stock. Bondina ged pegmatite appears i n Figure 19. Samples are from the southeast and east part of the stock margin. Scale i n inches and given by the hammer, n i c k e l and pen.  24  b) Area I I In t h i s area the contact between Mt. Carlyle stock and Slocan metasediment i s sharp i n 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 i n length are common ( F i g . 21 and Plate 1) along the stock margin.  The contact dips steeply  outward from the stock throughout most of t h i s area and the mapped " i r r e g u l a r i t y i s not a topographic The amount of quartz r i c h metasediment and  e f f e c t . (Plate 1) especially  of limestone i n the reentrants and roof pendants i s much greater than i n the nearby contact zones.  F o l i a t i o n i n the  metasediment strikes into the stock, often at a high angle to the contact.  The p a r a l l e l i s m of tectonic f o l i a t i o n and  stock margin described i n other contact areas i s absent here. Andalusite porphyroblasts developed i n t h i s area are randomly oriented, occuring both within the plane of dominant f o 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 f o l i a t i o n . Limestone i n the roof pendants i s intensely folded as delineatedby t h i n argillaceous layers.  The f o l d i n g i s  25  both concentric and disharmonic with variably oriented f o l d axes and „is probably related to emplacement of the surrounding g r a n i t i c rock.  These folds are shown i n Figures 22 and  23 and the roof pendant containing them i s seen i n Figure 2 1 . Plate 1 (if mile WNW  of Mt. Holmes) shows f o l i a t i o n and  f o l d axis measurements of a megascopic f o l d believed to be an accomodation structure related to emplacement of the stock. The folded beds are t h i n bedded impure argillaceous limestone, b i o t i t e schist, and quartzite i n order of decreasing abundance. The f o l d i s centered i n 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 i s characterized by a moderately steep contact that crosscuts the dominant f o l i a t i o n i n the country rocks.  Large  d i l a t i o n dikes and s i l l s occur above the contact where i t dips under the metasediments.  26 Figure  Figure  20: View looking northwest toward a large roof pendant at the head of the north branch of Montezuma Creek i n the northern portion of Mt. Carlyle stock. The roof pendant i s the dark area underlying the sumnjit of the mount a i n i n the photo. The roof pendant i s composed of argillaceous limestone.  toward 21: View looking north a limestone roof pendant i n Mt. Carlyle stock i n the v a l l e y of the nort'h branch of Montezuma Creek. The roof pendant i s the arcuate septum of outcrop just below tree l i n e i n the upper center of the photo.  27 F i g u r e s 2 2 and 2 3 :  T i g h t f o l d i n g i n the limestone r o o f pendant whown i n F i g u r e 2 1 . The f o l d i n g i s d e l i n e a t e d bybands of a r g i l l a c e o u s m a t e r i a l t h a t i s more competent than the limestone. Hammer and compass give s c a l e .  2o  c)  Area I I I  The t h i r d s t r u c t u r a l l y d i s t i n c t area i n the contact region of Mt. Carlyly stock i s characterized by w e l l developed  crenu-  l a t i o n of the dominant f o l i a t i o n , sharp contact between the stock and the metasediments,numerous large laucocratic porphyry dikes, t i g h t l y crumpled f a u l t zones, drag folds and a f o l i a t e d border phase of Mt. Carlyle stock. The dominant f o l i a t i o n i n t h i s area i s sub-parallel to the margin of the stock.  T  h i s orientation i s probably the r e s u l t  of warping of a pre-existing regional f o l i a t i o n during emplacement of the stock.  The dominant mica f o l i a t i o n i s  strongly crumpled i n outcrop and crenulated i n handspecimen near the stock margin.  In t h i n section the crenulation i s  seen to result from intersecting s l i p cleavages which have offset contact metamorphic porphyroblasts.  * i g e s 24, 25 and U r  26 show crenulation of a previous f o l i a t i o n . The contact i s normally sharp i n t h i s area and large leucoc r a t i c dikes have intruded along fractures, bedding planes and other zones of weakness i n the metasediments. Drag folds i n limestone with f o l d axes contained i n a plane approximately p a r a l l e l to the margin of Mt. Carlyle stock have sense of movement i n d i c a t i n g that the metasediments nearer the contact have moved up and l a t e r a l l y r e l a t i v e to those farther  29  from the contact,  The drag folds are.tighter and less sym-  metrical than f o l d i n g observed elsewhere i n the limestone (figures 22 and  23).  A zone of intense crumpling and strong fracture cleavage appears as a lineament i n a e r i a l photographs near the stock contact. The border phase of the stock i s well f o l i a t e d i n the southernmost portion of Area I I I . The contact here i s sharp and regular with well developed crenulation of the dominant f o l i a t i o n i n the metasediments.  30  Figure  2J+:  S t r a i n - s l i p cleavage which crenulates the previous layering and mica f o l i a t i o n and has disoriented andalusite porphyroblasts (white spots i n photo). Sample collected i n the south w a l l of the Twelve Mile Creek v a l l e y near the stock contact. Scale i n inches.  Figure  25:  Intensely crumpled f o l i a t i o n i h p e l i t e collected at the stock margin two miles north of Mt. Heyland. Scale i n inches.  Figure  26:  Intersecting crenulation cleavages seen i n the plane of the dominant mica f o l i a t i o n . The f o l i 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 i n inches.  31  d)  Area IV  The fourth s t r u c t u r a l l y 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 e a r l i e r emplacement of the bathol i t h r e l a t i v e to the stock to the north. A well developed f o l i a t i o n i s ubiquitous and i n the eastern and central portions of the area maintains a consistent strike of approximately 1 2 0 ° and a steep or v e r t i c a l d i p . This f o l i a t i o n strikes approximately p a r a l l e l to the margin of Mt. Carlyle stock.  Crenulation i n t h i s f o l i a t i o n i s shown  i n Figures 9 , 2 7 , and 2 & . Minor folds are well developed i n the f o l 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 i n Figures 29 and 3 0 . Near the margin of the Nelson Batholith i n the septum, minor f o l d s have been deformed such that t h e i r a x i a l  plane  cleavages fan s l i g h t l y and approximately p a r a l l e l the margin of the Nelson Batholith.  These folds are offset by two  intersecting fracture cleavages, one of which may develop p r e f e r r e n t i a l l y to the other.  The fracture cleavage i s  l o c a l l y the locus of i n c i p i e n t small fractures of f i n i t e r e l a t i v e displacement which offset the limbs of minor folds  32 as seen i n F i g u r e s 31 and 3 2 .  The f r a c t u r e cleavages i n t e r -  s e c t a t angles a v e r a g i n g approximately 30°, f r a c t u r e cleavages d e f i n e  a parting  Intersecting  i n the r o c k a l l o w i n g  matic breakage r e c o g n i z e a b l e i n hand specimen. defined  re  The l i n e a t i o n  by the i n t e r s e c t i o n o f the conjugate f r a c t u r e  i s steeply plunging.  Compton (1955) d e s c r i b e d  pris-  cleavages  similar fractu-  ( s l i p ) cleavages a t t r i b u t i n g t h e i r development t o f o r c e s  s e t up by an i n t r u s i v e p l u t o n a f t e r development of t h e dominant s c h i s t o s i t y i n the country r o c k s . The f r a c t u r e are o r i e n t e d  such t h a t the plane o f f o l i a t i o n i n t e r s e c t s t h e  acute angle between them. o r i e n t a t i o n i s that tening  cleavages  A possible  explanation f o r t h i s  the f r a c t u r e cleavages r e s u l t e d from t i g h -  o f e a r l i e r f o l d s due t o i n t r u s i o n o f Mt. C a r l y l e  stock.  A weak f o l i a t i o n s i m i l a r t o secondary f o l i a t i o n i n other  parts  of the septum occurs w i t h the s l i p cleavages and i n t e r s e c t s the main mica f o l i a t i o n a t a low a n g l e . and  This weak f o l i a t i o n  p o s s i b l y the accompanying f r a c t u r e cleavages are thought  to be r e l a t e d t o i n t r u s i o n o f Mt. C a r l y l e stock t o the n o r t h . Nearer t h e southwest margin o f the stock the dominant country rock f o l i a t i o n i s s u b - p a r a l l e l t o the f o l i a t e d border o f the stock.  The f o l i a t i o n i s c u t by l a r g e crumples and c r e n u l a t i o n  i n the schistose  l a y e r s and minor f o l d s a r e sheared out and  discontinuous. J o i n t s a r e abundant i n rocks o f 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 i n augen-like d i s t o r t i o n s i n the dominant mica f o l i a t i o n . Sample collected near the stock contact north of the confluence of Long and Keen Creeks. Scale i n inches.  Figure  2 8 : F o l i a t i o n i n metapelite containing large andal u s i t e porphyroblasts. Sample collected g mile north of Mt. Heyland. Scale i n inches.  Figures 2 9 O r i g i n a l layering and some reversed graded and 3 0 : bedding sub-parallel to f o l i a t i o n i n p e l i t i c schist | mile northeast of Mt. Heyland. Minor f o l d s are defined by l i g h t and dark layering and are much sheared and tightened. The darker layers have large andalusite porphyrob l a s t s . Scale given by hammer, pen and quarter.  fi . 5  27  34  Figure  31:  Minor folds i n interbedded p e l i t e and quartzi t e beds. The two rock types are i n dark and l i g h t colored layers. Note fanning of the a x i a l plane cleavage v i s i l b e at the top of the photo. Sample collected near the margin of the Nelson Batholith 2 | miles northwest of Mt. Heyland. Scale i n inches.  Figure  32:  Minor f o l d s with a small f a u l t that has d i s placed the limb of the f o l d on the l e f t i n the photo. The small f a u l t p a r a l l e l s a fracture cleavage making a small angle with the dominant mica f o l i a t i o n . Sample collected near where that i n Figure 31 was c o l l e c t e d . Scale i n inches. '  Figure  33:  Blocks of p e l i t i c schist with large andalusite porphyroblasts within the f o l i a t i o n . The block on the l e f t i s observed along the f o l i a t i o n and the block on the r i g h t i n the photo i s observed normal to the f o l i a t i o n . . Sample collected ^ mile northeast of Mt. Heyland. Scale given by peri and quarter.  35  where small f a u l t s were recognized.  One of these f a u l t  zones, indicated on Plate 1 upstream from the mouth of Long Creek, contains a dark grey mylonite along c l o s e l y spaced f r a c t u r e s . Large c h i a s t o l i t e porphyroblasts i n the central and western part of Area IV show internal features not seen i n s i milar porphyroblasts elsewhere i n the contact region of Mt. Carlyle stock.  The c r y s t a l structures here are pertinent  to the sequence of emplacement of the Nelson Batholith and Mt. Carlyle stock to the north.  C h i a s t o l i t e porphyroblasts  having i n t e r n a l features described below appear i n Figure 3 4 , 35,  36,  and  37.  In t h i s area c h i a s t o l i t e i s seen i n t h i n section to cont a i n abundant elongate quartz inclusions.  The inclusions,  as w e l l as cleavage traces i n the c r y s t a l s , are deformed and meet the surrounding groundmass f o l i a t i o n at variable angles. Lenticular quartz inclusions may have assumed t h e i r present shape during a deformation previous to that which produced the present crenulated f o l i a t i o n i n the rock.  Crystals en-  closing deformed quartz l e n t i c l e s exhibit no strained extinct i o n patterns.  Some evidence of s t r a i n would be expected i f  the porphyroblasts had not r e c r y s t a l l i z e d after deformation of the enclosed quartz l e n t i c l e s .  The amount of i n t e r n a l  c r y s t a l deformation i s independent of the present c r y s t a l  36  Figure  34:  C h i a s t o l i t e with deformed cleavage and small rod-like inclusions of quartz. The crystals are rimmed by a s e r i c i t e border. Sample c o l lected | mile northeast of Mt. Heyland.  Figure  35:  C h i a s t o l i t e with oriented inclusions i n the central part of the c r y s t a l . Wedge shaped reentrants of the groundmass of the rock occur i n the l e f t and right side of the c r y s t a l and curved cleavage and quartz i n clusions are v i s i b l e . Sample collected 1 mile downstream from the head of Long Creek.  Figures 36 and 3 7 :  Chiastolite with deformed l e n t i c u l a r quartz inclusions. Sample from the same l o c a l i t y as that shown i n figure 3 5 .  37  orientation.  The i n c l u s i o n - r i c h central area and wedge-like  reentrants of the groundraass i n the c r y s t a l i n Figure 35, i n tersect the groundmass f o l i a t i o n at a d i s t i n c t angle. suggests that the deformation that aligned  This  the inclusion-  r i c h areas was d i s t i n c t from that producing the present groundmass f o l i a t i o n . The ultimate character of the c h i a s t o l i t e porphyroblasts i s the r e s u l t of a growth i n stages y i e l d i n g concentric zones of s l i g h t l y d i f f e r e n t extinction orientation within the same crystal.  Occassional "piggy-back" c h i a s t o l i t e growth has  resulted i n two well developed c h i a s t o l i t e porphyroblasts sharing a common surface but with each c r y s t a l having a d i s t i n c t c h i a s t o l i t e inclusion  cross.  Many of the andalusite crystals are surrounded by a rim of s e r i c i t i c a l t e r a t i o n material.  In one l o c a l i t y at the mar-  gin of Mt. Carlyle stock northeast of Mt. Heyland s e r i c i t i c a l t e r a t i o n material i s completely pseudomorphic after  large  andalusite c r y s t a l s . Thin sections containing deformed c h i a s t o l i t e porphyroblasts also contain smaller knots of s e r i c i t e - c h l o r i t e a l teration material.  These smaller knots are the same shape  as fresh c o r d i e r i t e porphyroblasts at the margin of the Nelson Batholith one mile northwest of Mt. Heyland. Ident i f i c a t i o n of the c h l o r i t e knots as former c o r d i e r i t e  38  porphyroblasts  remains speculative owing to lack of rem-  nant c o r d i e r i t e 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 . C a r l y l e stock have been interpreted as being l a t e r than minor folds and f o l i a t i o n related to the emplacement of the Nelson Batholith to the south.  These features have been described i n the pre-  vious section and some of the s t r u c t u r a l features appear on Plate  1.  The large c h i a s t o l i t e porphyroblasts described i n the previous section suggest multiple deformation and thermal metamorphism i n the septum of Slocan Group metasediments between the Nelson Batholith and Mt. Carlyle stock.  A pos-  s i b l e history f o r the c h i a s t o l i t e porphyroblasts i s : 1)  Regional deformation followed by r e f o l d i n g of the low  grade metamorphic rocks during emplacement of the Nelson Batholith and development of a f o l i a t i o n p a r a l l e l to the margin of the Nelson Batholith.  The f i r s t c h i a s t o l i t e porphyro-  b l a s t s grew at t h i s time, possibly with small c o r d i e r i t e crystals. 2)  A t h i r d period of deformation due to emplacement of  Mt. Carlyle stock with s t r a i n i n g and l a t e r r e c r y s t a l l i z a t i o n of c h i a s t o l i t e c r y s t a l s .  The c r y s t a l s r e t a i n a record of  deformation i n the form of l e n t i c u l a r quartz inclusions and curved cleavages and are oriented parallel to the f o l i a t i o n  40  which p a r a l l e l s t h e southern margin o f Mt. C a r l y l e  stock,  s u g g e s t i n g r e c r y s t a l l i z a t i o n r e l a t e d t o emplacement o f the stock. 3)  Late r e t r o g r a d e metamorphism producing  sericite  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 pseudomorphs a f t e r c o r d i e r i t e near the margin o f Mt. C a r l y l e  stock.  -D. MODE OF EMPLACEMENT OF MT. CARLYLE STOCK Compton (1955, I960) and P i t c h e r (1963) d i s c u s s manner o f emplacement o f igneous p l u t o n s i n r e l a t i o n t o s t r u c t u r e s and t h e r m a l l y metamorphosed country rock surrounding the p l u t o n s . Features o f the contact r e g i o n o f Mt. C a r l y l e stock are i n d i c a t i v e o f the s t y l e of emplacement of the s t o c k . A broad  zone o f i n t e r m i x i n g o f metasediment and g r a n i t i c  rock a l o n g the e a s t e r n margin o f the stock i n d i c a t e s some degree of a s s i m i l a t i o n o f the metasediment by the s t o c k . F e l d s p a t h i s a t i o n o f the metasediment has produced q u a r t z o f e l d s p a t h i c g n e i s s i n the g r a d a t i o n a l c o n t a c t a r e a . become segregated  B i o t i t e has  i n the metasediment i n the c o n t a c t zone.  In the northern p o r t i o n o f the s t o c k numerous x e n o l i t h s and r o o f pendants a t t e s t t o p a r t i a l i n c o r p o r a t i o n o f the meta sediment i n t o the igneous r o c k .  Calcareous  metasediments  l o c a l l y s t r i k e i n t o the stock and a r e a b r u p t l y c r o s s c u t by  41  the stock margin.  I t i s t h i s area of the stock that  shown by S i n c l a i r and Libby (1967) t o be h i g h i n Ca r e l a t i v e to the southern p o r t i o n s o f the s t o c k .  was content  Sinclair  and Libby (1967) p o s t u l a t e a magmatic o r i g i n f o r the stock w i t h p o s s i b l e contamination i n the northern p o r t i o n . The  swing of r e g i o n a l f o l i a t i o n i n t o p a r a l l e l i s m w i t h the  stock margin i s s t r i k i n g .  T h i s suggests some accommodation  o f the stock by the surrounding metasediment. Along the n o r t h and west margins of the stock  igneous  d i k e s of composition s i m i l a r t o t h a t of the stock have i n truded a l o n g planes of weakness i n the countryrock.  Crumpling  and f r a c t u r i n g o f the surrounding rocks i n c r e a s i n g i n i n t e n s i t y nearer the stock margin p o s s i b l y i n d i c a t e s l a t e i n g by the p a r t i a l l y cooled igneous r o c k .  Well  shoulder-  developed  f o l i a t i o n i n the igneous border phases where the c o n t a c t w i t h the metasediment i s sharp i n d i c a t e s s h e a r i n g or f l a t t e n i n g near the borders o f the s t o c k . Magmatic o r i g i n of the stock i s suggested by the complex zoning and combination t w i n n i n g of p l a g i o c l a s e .  The marked  contact metamorphic a u r e o l e around the stock i n d i c a t e s the stock was  a source o f heat f o r the surrounding metasediments.  T i g h t f o l d s w i t h a x i a l planes co-planar w i t h  foliation  p a r a l l e l to the stock margin i n d i c a t e s h e a r i n g p a r a l l e l t o and f l a t t e n i n g p e r p e n d i c u l a r t o the  1  stockmargin.  42  A simple mechanism o f emplacement i s not compatible v a r i o u s f e a t u r e s presented above and a combination cesses must be invoked. 1  with  o f pro-  A magmatic body o f molten rock was  i n t r u d e d i n t o the Slocan Group metasediment by a process o f l a t e r a l accommodation, f o r c e f u l s h o u l d e r i n g , and a s s i m i l a t i o n i n order o f d e c r e a s i n g importance.  The border phases o f  the c o o l i n g stock were f o l i a t e d p a r a l l e l t o the stock margin during  emplacement.  III. A.  METAMORPHISM  SLOCAN GROUP SEDIMENTARY ROCKS  The non-metamorphic rock types o f the Slocan Group have been d e s c r i b e d i n a g e n e r a l way by C a i r n e s (1934) and Hedley (1952) but no d e t a i l e d s t r a t i g r a p h y has been proposed group.  f o r the  The present author has been unable t o f o l l o w any s t r a -  t i g r a p h i c h o r i z o n as i t passes from the r e g i o n a l g r e e n s c h i s t metamorphic t e r r a n e i n t o the c o n t a c t r e g i o n s o f M t . C a r l y l e stock.  However, the " s l a t e b e l t s " d e s c r i b e d by Hedley  can be  p r o j e c t e d a l o n g s t r i k e t o meet Mt-. C a r l y l e stock and a gener a l c o r r e l a t i o n o f c o n t a c t metamorphic rocks w i t h t h e i r g i n a l rock- types can be made.  T h i s procedure  ori-  a l l o c s no  d e t a i l e d c o n t r o l o f the degree t o which the Slocan Group has been a l t e r e d i n chemical composition d u r i n g contact metamorphism.  43  ;  Contact metamorphic rocks i n Mt. Carlyle region are d i s -  cussed under f i v e headings based on the present composition of the metamorphosed Slocan Group sedimentary rocks.  The f i v e  compositional d i v i s i o n s distinguished i n the present discussion are: limestone-marble  association, quartzite, potassic  to c a l c i c p e l i t e , magnesian p e l i t e , and ferrous p e l i t e . Areas dominated by each of these rock associations are i n d i cated on Plate 1. B. LIMESTONE-MARBLE ASSOCIATION Calcareous rocks i n the contact aureole of Mt. Carlyle stock are predominantly impure coarsely c r y s t a l l i n e and marble.  limestone  Carbonate units are most common along the north-  east margin of the stock and i n roof pendants i n the same region.  Crystal size of c a l c i t e i n 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.  T  he calcareous layers vary i n thickness  from a few inches to 300 f e e t . Minor folds are developed prominently i n the limestone near the contact with Mt. Carlyle stock.  Contact metamorphic s i l i -  cate minerals are not obviously abundant i n hand specimens from most l o c a l i t i e s .  Garnet has been reported i n calcareous  44  units i n the contact aureole but was not observed by the present  author.  Figure 3& shows t y p i c a l t h i n 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 i n some of the roof pendants i n the northern portion of the stock. Much of the quartzite i s pinkish, due to b i o t i t e and fibrolite.  Very near the-stock contact the quartzite i s horn-  f e l s i c i n appearance although mica f o l i a t i o n l o c a l l y i s weakly  developed. Along the western margin of the stock quartzite commonly  i s r e s t r i c t e d to t h i n bedded coarse grained members of graded beds.  Near the stock contact the quartzite increases i n K-  feldspar content as muscovite i s depleted and f i b r o l i t e mats develop rimming K-feldspar and b i o t i t e .  Figures 3 9 , 40,  and  41 show f i b r o l i t e mats growing i n a K-feldspar-plagioclasebiotite-muscovite groundmass.  45  Figure  3-3*  T h i n b e d d e d 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 . S a m p l e s c o l l e c t e d on t h e n o r t h slopes of M t . Holmes. Scale i n i n c h e s .  Figure  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 pegmatite vein'in t h i n l y interbedded quartai t e and s c h i s t . A f l a k e of muscovite crosscuts the f o l i a t i o n i n the lower l e f t corner 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 tact of M t . Carlyle stock 3 miles north of Mt. Heyland.  Figure  40:  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 musc 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 p e n d a n t at the eastern margin of M t . C a r l y l e s t o c k .  Figure  41*  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 feldspar grains. 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.  Pelitic  rocks  and p l a g i o c l a s e sedimentary Carlyle  rock  stock.  along the  rims  parallels strain  the  which has roblasts sic by  fcany  lated  to  Carlyle  margin of  the  is  a n d 45 stock  The  late stock.  stage  of  especially (Plate  Mt. abundant  1)  partially  the  same r o c k .  sericitized  The  plane. sericite  their  and fragmented  i n a region  i n a f o l i a t i o n which  crenulations  p a r a l l e l to  small fractures  meta-  in a foliation  show c r e n u l a t i o n s  i n a muscovite-quartz beds are  other  section.  margin.  cleavage  muscovite,  aureole  stock.  randomly o r i e n t e d  in thin  deformed  pelite  contact  a photomicrograph of  44  slip  the  K- and C a - r i c h r o c k  visible  Figures  in andalusite,  i n t e r l a y e r e d w i t h the  throughout  grains  is  43  are  occur  PELITE  shows a sample w i t h l a r g e  42  chiastolite Figure  typically rich  northwest  Figure  K-Ga RICH  a x i a l planes  altered  matrix.  andalusite  These h i g h l y  a l o n g Twelve  and i n t e n s e  shouldering of  result  Mile  from (Fig.45) porphypotas-  Creek cut  crenulation probably the  re-  country rock by Mt.  47  Figure  42:  C h i a s t o l i t e porphyroblasts i n random orient a t i o n within a f o l i a t i o n plane i n metapelite. Sample collected near the stock margin on the north wall of the Twelve Mile Creek v a l l e y . Scale i n inches.  Figure  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. Thin sect i o n of the same sample as shown i n Figure 4 2 .  Figure  44*  Crenulation i n layered metapelite. Note catac l a s t i c appearance of the l i g h t quartz grains. F o l i a t i o n p a r a l l e l to the layering i s due to alignment of muscovite and graphite. Sample collected i n south wall of the Twelve Mile Creek v a l l e y .  48  E.  MAGNBSIAN PELITE  Cordierite (Fig. 4 6 ) was recognized i n 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 l i g h t green to grey quartzose rock, and dark grey to pinkish s c h i s t .  The c o r d i e r i t e  i s i n knots that appear as black spots on a smooth unweathered surface, as brown rough knots on a p a r t i a l l y weathered surface, and as small p i t s on an intensely weathered surface. In the cordierite-bearing layers the f o l i a t i o n of the schist i s defined by orientation ofmmuscovite and b i o t i t e .  The  pinkish cast on the f o l i a t i o n surfaces i s due i n part to biot i t e but i s especially noticeable where f i b r o l i t e mats are developed.  The dominant f o l i a t i o n i s subparallel to o r i g i n a l  sedimentary layering. Some crossbeds are apparent i n the quartzose layers and are distinguished by concentration  of dark minerals along the  crossbeds. In t h i n section the c o r d i e r i t e i s p o i k i l o b l a s t i c i n diamond or l e n s - l i k e porphyroblasts.  Small b i o t i t e inclusions i n cor-  d i e r i t e are orientated p a r a l l e l to the b i o t i t e i n the surrounding groundmass.  The b i o t i t e inclusions are surrounded by  49  pleochroic halos. L o c a l l y , the c o r d i e r i t e share common boundaries The  porphyroblasts  and make up 75 percent o f the r o c k .  groundmass m i n e r a l s are muscovite,  quartz and p l a g i o c l a s e  i n d e c r e a s i n g order o f abundance. Sigmoidal i n c l u s i o n t r a i n s i n t h e c o r d i e r i t e were not observed, thus the growth may have been s t a t i c .  Some o f the  p o r p h y r o b l a s t s have "hatchure" p o l y s y n t h e t i c twins as w e l l as pseudohexagonal p e n e t r a t i o n t w i n s . B i o t i t e and muscovite a r e concentrated around the c o r d i e r i t e p o r p h y r o b l a s t s g i v i n g a " c h a i n l i n k " appearance t o t h e rock where the c o r d i e r i t e p o r p h y r o b l a s t s are c l o s e l y  spaced.  F i g u r e s 47 and 1+8 show c o r d i e r i t e i n t h i n s e c t i o n . M a t e r i a l from c o r d i e r i t e knots was x-rayed  a t a scanning  speed o f k° p e r minute from 29°-30° 2©, and an average d i s t o r t i o n index was c a l c u l a t e d u s i n g r e l a t i v e peak . p o s i t i o n s f o r reflections  (511) (421) and (131).  The d i s t o r t i o n index i n c r e a s e s i n p r o p o r t i o n t o the d e v i a t i o n o f the c o r d i e r i t e from i t s hexagonal polymorph i n an order-disorder relationship. index  ( M i y a s h i r o , 1957).  (A) i s given by the f o l l o w i n g r e l a t i o n s h i p : D  Where 2©^  2  2Qg and 2©^ are the d e v i a t i o n angles i n degrees  o f the peaks r e p r e s e n t i n g (511), A  The d i s t o r t i o n  (421) and (131) r e s p e c t i v e l y .  i n t h e present case i s 0.25 i n d i c a t i n g t h a t the c o r d i e r i t e i s  50  i n t e r m e d i a t e 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 distorted  indialite.  un-  51  Figure  45*  S e r i c i t i z e d andalusite porphyroblasts i n a muscovite-quartz matrix. Strain s l i p cleavage i s near v e r t i c a l i n the photo and has graphite concentrated along the cleavage planes. A lesser developed s t r a i n s l i p cleavage i n t e r sects the prominent s t r a i n s l i p cleavage shown here. Sample collected i n same area ss that shown i n Figure 4 4 .  Figure  46:  Cordierite knots i n 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 and 4 8 *  Cordierite porphyroblasts i l l u s t r a t i n g p o i k i l o b l a s t i c texture with inclusions of b i o t i t e and quartz. Biotite-muscovite intergrowths i n the groundmass are oriented i n a f o l i a t i o n and the biotite-muscovite i s arranged i n a chainl i k e pattern around the c o r d i e r i t e porphyrob l a s t s . Sample i s the same as that shown i n Figure 4 6 .  52  F.  FERROUS PELITE  A narrow band o f Fe p e l i t e borders a l o n g i t s southeast margin.  Mt.  C a r l y l e stock  I t i s i n t h i s band t h a t the  o n l y s t a u r o l i t e and garnet were r e c o g n i z e d i n the map  area.  Some o f the t e x t u r a l r e l a t i o n s h i p s o f the F e - p e l i t e s are i n c l u d e d i n t h i s s e c t i o n and'are summarized i n F i g u r e 49 where the number of observed  i n s t a n c e s of c o n t a c t of the  v a r i o u s m i n e r a l phases i s r e c o r d e d .  The  cordierite  indica-  ted  on t h i s t a b l e i s from the M g - p e l i t e a t the northwest mar-  gin  o f the Nelson  Batholith.  F i r s t occurrences of the key contact metamorphic m i n e r a l s i n the r e g i o n surrounding Mt. the i s o g r a d map,  F i g u r e 50.  C a r l y l e stock are i n d i c a t e d  on  M i n e r a l assemblages i n the con-  t a c t metamorphic r o c k s are i n d i c a t e d i n p r o j e c t i o n i n the A'FM  plane  F i g u r e 51.  (Thompson, 1957) S i m i l a r A'FM  diagrams were employed by Green  i n r e p r e s e n t i n g r e g i o n a l and semblages from n o r t h e r n New produced the observed  o f the A-K-F-M t e t r a h e d r o n i n (1963)  c o n t a c t metamorphic m i n e r a l a s Hampshire. P o s s i b l e r e a c t i o n s which  m i n e r a l assemblages are l i s t e d i n F i g u r e  50b. S t a u r o l i t e and garnet f i r s t appear i n the contact aureole of Mt;  C a r l y l e stock i n the same o u t c r o p s . Thus, i n most areas  the s t a u r o l i t e and 51.  garnet i s o g r a d s are superimposed i n F i g u r e  CHLORITE  BIOTITE BIOTITE  GARNET GARNET  STAUROLITE STAUROLITE  ANDALUSITE A N C A L U SITE  SILLIWAMTE SILLIMANITE  CORDIERITE CORDIERITE  MUSCOVITE  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 phases i n the c o n t a c t metamorphic a u r e o l e  between m i n e r a l of Mt. C a r l y l e stock  fig. 5 0  Map of Mt. Carlyle stock and inferred isograds i n the contact metamorphic aureole  55 MINERAL ASSEMBLAGES  Muscovite - c h l o r i t e - a l b i t e - quartz  Regional  p h y l l i t i c greenschist H  Sf  Muscovite  b i o t i t e - plagioclase - quart + c h l o r i t e  Muscovite  andalusite - b i o t i t e - plagioclase - quartz  co  o  staurolite - b i o t i t e - plagioclase - quartz o Muscovite co + andalusite o :>> Muscovite - garnet - b i o t i t e - plagioclase - quartz •p •H + andalusite X  u  P-.  Muscovite - garnet - s t a u r o l i t e - andalusite - plagioclase + quartz  •H  CQ  ct$  Muscovite  CD  o  Andalusite  cordierite - b i o t i t e - plagioclase - quartz s i l l i m a n i t e - b i o t i t e - muscovite - plagioclase - quartz  M  S i l l i m a n i t e + b i o t i t e + K-feldspar + plagioclase + quartz  PROPOSED MINERAL REACTIONS  1. Chlorite + muscovite  '  andalusite + b i o t i t e + quartz + HgO  2. Chlorite + muscovite + quartz 3. Fe-Mg c h l o r i t e + quartz  cordierite + b i o t i t e + rL,0  Almandine + Mg-chlorite  4. Garnet + b i o t i t e + andalusite  s t a u r o l i t e + muscovite  + h^O + quartz 5. Andalusite ± ^ s i l l i m a n i t e 6. Muscovite + Quartz F i g . 50b  K-feldspar + s i l l i m a n i t e + h^O Mineral assemblages and possible mineral reactions i n p e l i t i c metasediment from the contact aureole of Mt. Carlyle stock.  Pyrophyllite  A*FM diagrams f o r contact metamorphic assemblages i n the aureole o f M t . C a r l y l e s t o c k .  56  FIG.51  57  Figures 5 2 , 5 3 , 5 5 , and 56 show t y p i c a l t e x t u r a l r e l a tionships between garnet and s t a u r o l i t e and the relationships of these minerals to andalusite and b i o t i t e . Figure 52 shows a subhedral s t a u r o l i t e and a euhedral garnet i n 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 b i o t i t e i n the f o l i a t i o n remain i n the staur o l i t e and continue as a component of the groundmass f o l i a t i o n after passing through the s t a u r o l i t e c r y s t a l .  The same cross-  cutting r e l a t i o n between a large garnet porphyroblast and the groundmass f o l i a t i o n i s seen i n Figure 6 0 .  Individual graphi-  te inclusions i n some instances remain intact where they cut the boundary between a s t a u r o l i t e porphyroblast and the f o l i a ted groundmass.  Crenulationsin the groundmass f o l i a t i o n are  recorded i n inclusion t r a i n s within the staurolite grains and possibly indicate a s t a t i c growth of the porphyroblast a f t e r the deformation which crenulated the groundmass f o l i a t i o n . Figure 53 shows two s t a u r o l i t e porphyroblasts with curved i n clusion t r a i n s which pass undeflected into the groundmass f o l i ation. Small euhedral garnet porphyroblasts show no evidence of rot a t i o n or cataclasis and are commonly included i n b i o t i t e r i c h areas of the groundmass f o l i a t i o n . (Figure 5 2 . ) C h i a s t o l i t e porphyroblasts i n the Fe-pelite have grown i n multiple stages recognizable as composite overgrowths with  58  Figure  52:  A subhedral staurolite porphyroblast (left c e n t e r ) and a e u h e d r a l g a r n e t ( r i g h t center) i n b i o t i t e f o l i a t i o n . Graphite, forming part of the f o l i a t e d groundmass, passes as i n c l u s i o n s t h r o u g h the s t a u r o l i t e c r y s t a l . Sample c o l l e c t e d near the stock margin i n the west w a l l o f Keen Creek s o u t h o f Montezuma C r e e k .  Figure  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 the groundmass f o l i a t i o n w h i c h meets 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 . Sample 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 52.  Figure  54*  Andalusite crystal stages of growth: Stage  that  has  formed d u r i n g  three  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 of the center of the photo 2 - I n c l u s i o n r i c h zone i r r e g u l a r l y d e v e l oped s u r r o u n d i n g the i n i t i a l stage of the c r y s t a l 3 - Outer p o r t i o n of the c r y s t a l i n contact w i t h the f o l i a t e d b i o t i t e r i c h groundmass !  Stage Stage  The 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 and 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 . Sample c o l l e c t e d i n west w a l l o f Keen Creek v a l l e y 2 m i l e s north of Long Creek.  59  s l i g h t l y d i f f e r e n t e x t i n c t i o n directions than e a r l i e r portions of the c r y s t a l . (Figure 5 4 ) The portion of the grain developed during the f i r s t phase of growth i s inclusion free, o f f center with respect to the remaining portions of the c r y s t a l , and i s surrounded by an overgrowth with abundant inclusions. A second overgrowth i s inclusion-free and forms the outer border portion of the grain. developed  The outer growth phase i s unequally  around the inner portion.  C h i a s t o l i t e porphyroblasts have concentrations of b i o t i t e along t h e i r borders as i l l u s t r a t e d i n Figure 5 6 .  Figure 5 6  also shows another t e x t u r a l relationship very common i n the Fep e l i t e ; tendency f o r garnet and s t a u r o l i t e to develop i n the b i o t i t e - r i c h groundmass bordering c h i a s t o l i t e grains. Figure 5 5 , 5 6 , and 5 8 a l l show garnet and/or staurolite  developed  euhedrally or subhedrally against c h i a s t o l i t e porphyroblasts. Figure 5 8 i s of special interest because i t i l l u s t r a t e s the occassional coexistence of 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 i n a t e x t u r a l relationship which indicates no disequilibrium textures among the four phases.  obvious  Biotite-muscovite  f o l i a t i o n wraps around c h i a s t o l i t e but i s crosscut by both s t a u r o l i t e and garnet.  Thompson  (1957)  shows that i f t h e mineral  phases garnet, s t a u r o l i t e , andalusite and b i o t i t e are considered i n the three component system Al-Fe-Mg that only three of these four phases can coexist i n equilibrium. Best and Weiss  (1964,  60  Figure  55:  C h i a s t o l i t e on the l e f t i n the photo i s rimmed with muscovite and b i o t i t e . Staurol i t e i n upper center of the photo i s i n the circum andalusite position t y p i c a l i n the ferrous p e l i t e . Sample collected 2 miles north of Long Creek i n the bed of Keen Creek.  Figure  56:  Staurolite (right) showing inclusion trains continuous with the biotite-muscovite f o l i a t i o n enveloping the c h i a s t o l i t e on the l e f t . Sample i s the same as that i n Figure 5 5 .  Figure  57*  Two staurolite porphyroblasts penetrating a c h i a s t o l i t e c r y s t a l . Sample collected i n 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 i n the rock exceed a l i m i t , an extra phase could form to accommodate the excess components above that which can be accepted by the three phases i n equilibrium. Ext e r n a l l y controlled humidity may  cause extra phases to form  by temporarily f l u c t u a t i n g the amount of excess water i n the system.  Without a knowledge of the zoning i n the garnet and  other minerals present i t i s d i f f i c u l t to state which of these or other f a c t o r s may account f o r the extra phases. Figure 59 shows small c h i a s t o l i t e grains developed p e l i t e immediately  i n meta-  adjacent to the margin of Mt. Carlyle stock.  The small c h i a s t o l i t e s as w e l l as small inclusion-free garnets near the stock contact contrast with the larger c h i a s t o l i t e s and subhedral and anhedral garnets farther from the stock margin.  The smaller porphyroblasts near the stock possibly repre-  sent a d i s t i n c t generation of crystals but lack of other supporting evidence and the small number of t h i n sections p e r t i nent to the problem r e s t r i c t the idea to speculation. Sigmoidal i n c l u s i o n t r a i n s i n large c h i a s t o l i t e porphyroblasts which meet the groundmass at a high angle possibly i n d i cate r o t a t i o n a l growth with f l a t t e n i n g of the c r y s t a l s previous to development of the present f o l i a t i o n i n the rock. Staurolite possibly grew a f t e r development of the main mica f o l i a t i o n i n  62  Figure  58:  From l e f t to r i g h t i n the photo: staurol i t e , c h i a s t o l i t e , garnet and i n the upper and lower right side b i o t i t e . The four mineral phases seem to be i n equilibrium and have sharp boundaries between them. Sample collected i n Keen Creek 2 miles north of Long Creek.  Figure  59*  Small c h i a s t o l i t e porphyroblasts with biot i t e and muscovite adjacent to the contact with Mt. Carlyle stock. Sample collected 2 miles north of Long Creek i n the north wall of Keen Creek.  Figure  60:  Large subhedral garnet porphyroblast with opaque inclusions p a r a l l e l to the b i o t i t e muscovite f o l i a t i o n of the groundmass of the rock. Sample collected 2js miles north of Long Creek i n Keen Creek.  63  the rock and i s e s p e c i a l l y abundant along the edges of chiastolite crystals.  One of the euhedral staurolite crystals that  penetrates a c h i a s t o l i t e grain has incorporated the inclusion t r a i n of the c h i a s t o l i t e without d e f l e c t i n g the t r a i n .  The same  s t a u r o l i t e c r y s t a l crosscuts the mica f o l i a t i o n which has been warped around the c h i a s t o l i t e grain.-  This probably indicates an  overprinting of the staurolite grain upon the c h i a s t o l i t e grain. Composite s t a u r o l i t e c r u s t a l s at the end of c h i a s t o l i t e grains have developed within the projected outline of the chiast o l i t e grains suggesting staurolite nucleation at the s i t e of a pre-existing c h i a s t o l i t e graim;within the former c h i a s t o l i t e boundary. Plagioclase i s very f i n e grained i n the outer portions of the contact metamorphic region but coarsens nearer the stock margin. Five or more suitable grains were determined i n each of twelve t h i n sections from the inner contact aureole and a l l are c a l c i c oligoclase (An22 to 30).  A general increase i n An content to-  ward the stock margin was  observed although reversals were noted.  Judging the distance to the contact of the stock was  complicated  i n areas where the contact i s gradational. Large muscovite flakes crosscut the dominant biotite-muscovite f o l i a t i o n i n the inner part of the contact metamorphic region. These flakes possibly l i e along an incipient s t r a i n s l i p cleavage i n t i g h t l y crenulated areas near the stock margin.  64  G. The  SUMMARY OF MICROTEXTURAL INTERPRETATIONS  c o n t a c t metamorphic m i n e r a l s are predominantly  syn-  and  p o s t - d e f o r m a t i o n a l near the stock margin but are pre- a b r i t t l e deformation  i n the northwestern  contact r e g i o n where a n d a l u s i -  t e s have been broken, r o t a t e d and a l t e r e d along m i c r o f r a c t u r e s and  strain slipcleavage.  The  c o n t a c t metamorphic m i n e r a l pha-  ses grew i n the f o l l o w i n g o r d e r : c h l o r i t e , b i o t i t e , a n d a l u s i t e , s t a u r o l i t e and garnet, and  sillimanite.  A n d a l u s i t e c r y s t a l s w i t h m u l t i p l e overgrowths and  some along }  the southern margin o f the stock r e t a i n i n g r e l i c t s of an deformationjare  r e l a t e d to i n t r u s i o n of Mt.  the Nelson B a t h o l i t h t o the south.  C a r l y l e stock  earlier and  Late r e t r o g r a d e metamorp-  ism has r e s u l t e d i n s e r i c i t e rims around a n d a l u s i t e , c h l o r i t e knots p o s s i b l y a f t e r c o r d i e r i t e , and  l a r g e muscovite f l a k e s c u t -  t i n g the dominant mica f o l i a t i o n at a h i g h  angle.  The p r o g r e s s i o n o f c o n t a c t metamorphic m i n e r a l assemblages observed may  i n the metasediments oh' approach to the stock margin  approximately  i n d i c a t e the m i n e r a l o g i c a l changes d u r i n g a  temperature i n c r e a s e as r e s u l t of emplacement of Mt. stock.  However,  Carlyle  the s c a r c i t y of replacement t e x t u r e s i n the  c o n t a c t metamorphic r e g i o n s p o s s i b l y i n d i c a t e s t e l e s c o p i n g of the temperature dependent m i n e r a l r e a c t i o n s upon r a p i d h e a t i n g r e s u l t i n g i n bypassing near the s t o c k margin.  of i n t e r m e d i a t e temperature assemblages  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 s t a r t i n g 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 i n Mt. Carlyle area. Kyanite was not observed i n the contact aureole of Mt. Carlyle stock.  Andalusite i s well developed i n the outer aure-  ole and f i b r o l i t i c s i l l i m a n i t e occurs nearer the stock i n d i c a t i n g ( F i g . 61) that pressure at the time of metamorphism was probably between 2 . 7 and 6 K b .  Newton (1966) indicated l i m i t s  of uncertainty f o r the t r i p l e point of approximately 2 . 2 and 5.5  Kb. Newton*s r e s u l t s indicate that contact metamorphism i n  the present area took place at temperatures  of at least 400° c  and up to approximately 6 5 0 ° c. Richardson, B e l l , and Gilbert (1967)  obtained results which  agree well with those of Newton and found that varying water content i n the experimental runs had l i t t l e effect on the A 1 S 1 0 ^ t r a n s i t i o n reactions. The l i m i t s of uncertainty of 2  both Richardson and Newton and the v a r i a t i o n i n other published t r i p l e point positions affords only general conclusions as to temperature  and pressure based on AlgSlO^ t r a n s i t i o n s .  Schreyer and Yoder (1964) using a variety of natural and  66  synthetic materials, produced a s t a b i l i t y diagram f o r Mgc o r d i e r i t e under hydrous and anhydrous conditions.  The curve  for the lower s t a b i l i t y l i m i t of Mg-cordietite under hydrous conditions appears i n Figure 6 1 .  Schreyer (1964) noted that under  anhydrous conditions the s t a b i l i t y f i e l d f o r Mg-cordierite i s much more r e s t r i c t e d below the melting curve of granite. S hreyer and Yoder (1964) have determined a melting curve c  f o r 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  (1963).  This curve represents a high temperature l i m i t under hydrous conditions f o r contact metamorphism and i s reproduced i n F i g ure 6 1 .  This curve i s displaced toward higher temperatures un-  der anhydrous conditions. Figure 6 1 indicates that the Mg-cordierite curve intersects the melting curve f o r granite a t 7 K b . indicating a maximum pressure under which c o r d i e r i t e would be l i k e l y to form i n metamorphic rocks. F i e l d occurances of s t a u r o l i t e (Read, 1 9 5 2 ) (Zwart, 1 9 6 2 ) indicate that i t i s a common mineral i n metamorphic f a c i e s series containing andalusite, c o r d i e r i t e and garnet.  The pressure-  temperature, conditions giving r i s e to such assemblages are typic a l l y intermediate between contact and regional metamorphism. Figure 6 1 (dotted curves) includes a s t a b i l i t y f i e l d f o r s t a u r o l i t e (Hietanen, 1 9 6 7 ) inferred from f i e l d relations  67  rather than based on experimental data. Hietanen  (1967)  in-  cluded a different A l S i O ^ phase diagram than that i n i g u r e 6 1 . F  2  The  s t a u r o l i t e s t a b i l i t y f i e l d i n Hietanen s compositeP-T diaf  gram f e l l well within the s t a b i l i t y f i e l d of andalusite and s l i g h t l y within that of s i l l i m a n i t e near the t r i p l e point. Hietanen*s s t 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 s t a u r o l i t e possibly i n dicates pressures near the upper pressure l i m i t of andalusite. Richardson  (1968)  investigated  the relations i n the system  Fe-Al-Si-O-H between Fe-staurolite, Fe-cordierite, almandine, F e - c h l o r i t o i d , quartz and s i l l i m a n i t e .  Reaction curves f o r the  reactions: Fe-staurolite + quartz-±; Fe-cordierite  + s i l l i m a n i t e + H^O  F e - c h l o r i t o i d + s i l l i m a n i t e ±? Fe-staurolite + quartz + H^O are indicated by dashed l i n e s on the P^ Q-T diagram of f i g . 6 1 . As shown i n figure 6 1 the s t a b i l i t y f i e l d f o r Fe-staurolite + quartz spans a temperature range of approximately 1 5 0 ° and i t s lower pressure l i m i t i n rocks where cordierite forms i s approximately l j Kb.  Where c o r d i e r i t e has a higher ^ / F e ration than  that considered by Richardson the lower s t a b i l i t y l i m i t of }  s t a u r o l i t e r i s e s as does the upper l i m i t of c o r d i e r i t e s t a b i l i t y . Richardson's work indicates that i n ferrous-pelite of the present study, where no c o r d i e r i t e was observed, minimum f l u i d  68  1  2  3 T °c  • 61  4 x  5  6  7  100  P ^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 to rocks i n H  the contact metamorphic aureole of M t . C a r l y l e  stock  69  pressure possibly was 3jKb. and almost c e r t a i n l y exceeded 1^ Kb. with minimum temperature of at least 500° c. Ganguly (1968).. suggests that the s t a b i l i t y f i e l d of staurol i t e may be highly dependent on oxygen fugacity even i n rocks having the same bulk composition. may a c t u a l l y cut across isotherms.  The isograd for s t a u r o l i t e The effects of extra com-  ponents such as Cao and Mno i n a system may cause the s t a b i l i t y l i m i t s of s t a u r o l i t e to be shifted s i g n i f i c a n t l y . Evans (1965) determined an equilibrium curve f o r the react i o n Muscovite + quartz  K-feldspar + AL^SiO^ + H 0. This 2  curve i s reproduced i n Figure 61 and i s applicable to the highest temperature part of the contact aureole of Mt.Carlyle stock.  The r e a c t i o n curve f o r muscovite meets the minimum mel-  t i n g curve f o r 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 i n the rocks bordering Mt. Carlyle stock during contact metamorphism were probably i n 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 b u r i a l beneath the surface of the earth and mineralogic assemblages just discussed indicate that the true  70  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 b u r i a l , since stress a r i s i n g from emplacement of Mt. Carlyle stock and contact metamorphic dehydration reactions possibly increased the f l u i d pressure someivhat. The area shaded i n Figure 61 i s a graphical estimate of Pg Q -T conditions f o r the present contact metamorphic area. In constructing a diagram such as Figure 61 i t i s 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 p a r t i c u l a r curves selected and t h i s  esti-  mate would be shifted s i g n i f i c a n t l y i f experimental curves of d i f f e r e n t workers were employed,  figure £i gives only a q u a l i -  t a t i v e idea of conditions of metamorphism i n the present area.  71 IV. CONCLUSIONS  Emplacement of Mt. Carlyle stock was accomplished  through  variable mechanisms as evidenced by varying contact e f f e c t s 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 g r a n i t i c rock suggesting p a r t i a l assimilation of country rock. Northern stock margins contain large limestone roof pendants and many inclusions of country rock. Stock margins crosscut the trend of bedding i n calcareous units; a feature unique to t h i s 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 i n the stock. Metasediment along northwestern and western stock margins i s characterized by increasing i n t e n s i t y and frequency of large crumples, crenulation along s l i p cleavages, intrusive dikes, and f a u l t s . Altered contact metamorphic porphyroblasts have been a f fected by s t r a i n s l i p crenulation suggesting the stock has possibly imposed stresses on the country rock a f t e r the main thermal event i n the contact aureole. In a septum of metasediment between the southern margin of  72  Mt. Carlyle stock and the Nelson Batholith, a mica f o l i a t i o n i s prominent p a r a l l e l to margins of both bodies.  In the wes-  tern part of t h i s septum, t i g h t folds marginal to the Nelson Batholith have been deformed and tightened.  These tightened  f o l d s are crosscut by a weak f o l i a t i o n p a r a l l e l to the margin of Mt. Carlyle stock and by i n t e r s e c t i n g fracture cleavage that i s possibly related to stress imposed by intrusion of the stock. Near Mt. Carlyle stock, i n the western part of the septum, minor folds are very t i g h t , sheared out, and discontinuous.  These structures suggest that emplacement of the stock  occurred a f t e r emplacement of the Nelson B a t h o l i t h .  This  suggestion, i s supported by evidence of r e c r y s t a l l i z a t i o n withi n large c h i a s t o l i t e 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 deformation p r i o r to f i n a l c r y s t a l l i z a t i o n of the porphyroblasts. Microtexture"3 i n Fe p e l i t e along the eastern stock margin i n dicate that s t a u r o l i t e and garnet grew a f t e r development of biotite foliation.  Fabric of inclusions i n s t a u r o l i t e and gar-  net i s continuous with s i m i l a r f a b r i c i n the groundmass of the rock.  Ocassionally i n c l u s i o n t r a i n s outline e a r l i e r cre-  nulations that have been incorporated into growing s t a u r o l i t e and garnet c r y s t a l s .  Groundmass f o l i a t i o n commonly warps  around c h i a s t o l i t e porphyroblasts although f o l i a t e d b i o t i t e  73  layers are terminated against s t a u r o l i t e and garnet porphyroblasts. S i l l i m a n i t e forms from muscovite, b i o t i t e , and andalusite i n various parts of the contact aureole. In Mg p e l i t e , c o r d i e r i t e i s p o i k i l o b l a s t i c and probably grew after the main b i o t i t e f o l i a t i o n was  developed.  The microtextures suggest the following approximate sequence of mineral development although no single outcrop contains a l l of the mineral phases: b i o t i t e , andalusite, staurol i t e and garnet, c o r d i e r i t e and s i l l i m a n i t e . R e l i c t i n c l u s i o n t r a i n s indicate that deformation of the rock began before development of contact metamorphic minerals. Late s t r a i n s l i p cleavage associated with retrograde metamorphism has disturbed older andalusite porphyroblasts i n d i c a t i n g that deformation outlasted the main contact metamorphic recrystallization . The contact metamorphic aureole surrounding the stock suggests 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 i n part, of magmatic o r i g i n . Recent experimental work on P  H  Q -T s t a b i l i t i e s of the meta-  morphic minerals i n the contact aureole allow a general e s t i mate of conditions prevailing during emplacement of Mt.Carlyle stock.  74  The high temperature l i m i t of metamorphism under hydrous conditions i s the minimum melting curve of granite. The absence of kyanite i n the present area possibly l i m i t s P to 6|Kb. or l e s s .  H  Q  The occurrence of s i l l i m a n i t e i n high S  temperature parts of the aureole possibly indicate a minimum P  H 0  o  f  2  ^  K b  *  2  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  lower l i m i t of Fe-staurolite i n the presence of c o r d i e r i t e and a 3|Kb. l i m i t where c o r d i e r i t e i s absent. Conditions i n the contact aureole of Mt. Carlyle stock during thermal metamorphism were possibly i n the H G p  2  r a n  S  e  o  f  2|Kb. to 7Kb. and i n 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, M i n e r a l o g i c a l r e l a t i o n s i n some P e l i t i c H o r n f e l s e s from the Southern S i e r r a Nevada, C a l i f o r n i a : Amer. Min., vol.49, p.1240-1266. C a i r n e s , C.E., 1934, S l o c a n M i n i n g C mp, B.C.: G e o l . Surv.Canada, Mem. 173. a  Compton, R.R., 1955, Trondhjemite B a t h o l i t h Near B i d w e l l 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, A n a l y s i s o f the s t a b i l i t i e s o f c h l o r i t o i d and - s t a u r o l i t e and some E q u i l i b r i a i n the system FeO-Al-O^-SiOp-rLO-O-: A.J.S., v o l . 266, p.2972<^8 <- 5 <~ £ <~ Green, J.C.,1963, High L e v e l Metamorphism o f P e l i t i c Rocks i n Northern New Hampshire: Amer.Min., vol.4#, p.9911023. Hedley, M.S., 1952, Geology and ore D e p o s i t s o f the Sandon Area, S l o c a n M i n i n g Camp, B.C.: B.C.Dept.Mines, B u l l . 29. Hietanen, A., 1967, On the F a c i e s S e r i e s i n V a r i o u s Types of Metamorphism: Journ.of Geol., vol.75, no. 2. I r w i n , A.B., 1951, Mapping Complex F o l d s i n the S l o c a n S e r i e s , B.C.: Trans. Can.Inst.Mining Met., v o l . 54, pp. 494-501. , 1952, D i s c u s s i o n on Mapping Complex F o l d s i n the Slocan S e r i e s , B.C.: T r a n s . Can.Inst.Mining Met., v o l . 55, pp. 242-244. L i t t l e , H.W., I960, Nelson Map-Area, West H a l f , B.C.; Geol.Surv.Canada, Mem.308. M i y a s h i r o , A., 1957, C o r d i e r i t e - I n d i a l i t e R e l a t i o n s : 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 e q u i l , a t 7 5 0 ° c: S c i e n c e , v o l . 151, p. 1 2 2 2 - 1 2 2 5 . , 1966b, K y a n i t e - a n d a l u s i t e e q u i l . from 700° t o 800° c: S c i e n c e , v o l . 1 5 3 , p. 1 7 0 - 1 9 2 . P i t c h e r , W.S., R a d , H.H., 1963, Contact Metamorphism i n R e l a t i o n t o Manner o f Emplacement o f t h e G r a n i t e s o f Donegal, I r e l a n d : Journ. Geol., v o l . 71, no.3, 1963. e  Read, H.H., 1952, Metamorphism and Migraatization i n t h e Ythan V a l l e y , 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 F e - S t a u r o l i t e and Q u a r t z : Carnegie I n s t .Wash., Yearbook 67, p p . 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 I n s t . Wash., Yearbook 67, p . 3 9 2 - 3 9 7 . Schreyer, W., Yoder, H.S.Jr., 1 9 6 4 , The System M g C o r d i e r i t e H_0 and r e l a t e d r o c k s : 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 L i b b y , W.G., 1967, D i s t r i b u t i o n o f Major M i n e r a l s i n a Stock o f Nelson P l u t o n i c Rock, South C e n t r a l B.C.: Abs., Can.Min., v o l . 9 , p. 3 0 8 . ?  Thompson, J.B., J r . , 1957, G r a p h i c a l A n a l y s i s o f M i n e r a l Assemblages i n P e l i t i c S c h i s t s : Amer. Min., v o l . 42, pp.842-853. Yoder, H.S., 1955, Role o f Water i n Metamorphism: P*£pe;r 62, 1955, pp. 505-524-  GSA, Spec.  Zwart, H.J., 1958, R e g i o n a l Metamorphism and Related G r a n i z a t i o n i n the V a l 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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