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A garnet-bearing syenite near Kamloops, B.C. Kwak, Teunis A. P. 1964

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A GARNET-BEARING SYENITE NEAR KAMLOOPS, B. C. by TEUNIS A. P. KWAK A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of GEOLOGY AND GEOGRAPHY We accept t h i s thesis as conforming to the required standard from candidates f o r the degree of MASTER OF SCIENCE. THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , I96U I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study® I f u r t h e r a g r e e t h a t p e r -m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r ' s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e Head o f my D e p a r t m e n t o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t , c o p y i n g o r p u b l i -c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f The U n i v e r s i t y o f B r i t i s h C o l u m b i a , V a n c o u v e r 8, Ca n a d a ABSTRACT The main f e a t u r e s of a s y e n i t i c complex l o c a t e d near Kamloops B.C. are described. The most noteworthy of these i s the abundance of andradite garnet i n the r o c k s . The mineral i s "believed to have c r y s t a l l i z e d from a melt t h a t had the composition of quartz s y e n i t e . The melt , p r i o r to i t s c o n s o l i d a t i o n ,intruded .' and apparently a s s i m i l a t e d limestone. This caused the rocks to be d i f f e r e n t i a t e d at or near t h e i r present s i t e by the c r y s t a l l i z a t i o n of calcium s i l i c a t e s such as the andradite garnet. Quartz - r i c h rocks were produced f i r s t and u l t i m a t e ^ nepheline -bearing ones. i i i . TABLE OF CONTENTS CHAPTER PAGE I. GENERAL STATEMENT 1 LOCATION AND ACCESSIBILITY 1 NATURE OF AREA. 1 PREVIOUS WORK 2 ACKNOWLEDGEMENT 2 I I . GENERAL GEOLOGY OF THE AREA U REGIONAL SETTING k CACHE CREEK GROUP k I I I . GEOLOGY OF THE IGNEOUS COMPLEX 10 GENERAL STATEMENT 10 ROCK TYPES 1 0 THE QUARTZ MONZONITE INTRUSION 2 ? SIMILARITIES AND DIFFERENCES OF THE SYENITE AND THE QUARTZ MONZONITE INTRUSIONS 3 1 STRUCTURE 3 1 IV. DESCRIPTIVE MINERALOGY 3k AEGIRINE-AUGITE 3k ANDRADITE GARNET 3k FELDSPARS 3 8 V. CRYSTALLIZATION OF ROCK TYPES 1£ VARIATION DIAGRAM U2 SEQUENCE OF CRYSTALLIZATION OF THE ROCK TYPES k3 VI. ORIGIN OF THE COMPLEX U5 VII. RELATION OF THE SYENITE TO THE QUARTZ MONZONITE h$ VIII. CONCLUSIONS 50 L i s t of I l l u s t r a t i o n s Figure Page Fig . 1 View from Summit of Mount Fleet looking southwest. 1 F i g . 2 View from the Mount Lolo road. 2 F i g . 3 Regional Geology - Map 5 F i g . U Topography and Outcrop - Map 11 F i g . $ Structural Geology - Map 12 F i g . 6 Geology - Map 13 F i g . 7 Photomicrograph of a thi n section of hornfels specimen showing andalusite. 7 F i g . 8 Photomicrograph of thi n section of skarn showing garnet and amphibole i n c a l c i t e . 7 F i g . 9 Photomicrograph of a thin section of porphyritic quartz syenite. lU F i g . 10 Photograph of a hand specimen of quartz syenite. 1$ F i g . 11 Photomicrograph of o p t i c a l l y discontinuous oligoclase core of microperthite c r y s t a l i n quartz syenite. 16 F i g . 12- Photograph of w e l l aligned feldspar laths i n syenite. 17 F i g . 13 Photograph of s w i r l l i k e orientation of feldspar laths i n syenite. 17 F i g . l h Photograph of e l l i p s o i d a l feldspars i n syenite. 18 F i g . 15* Photomicrograph of hourglass-textured feldspars i n syenite. 17 Fi g . 16 Photomicrograph showing plagioclase p a r t i a l l y replaced by garnet. 19 F i g . 17 Photomicrograph showing amphibole apparently replacing aegirine-augite. 19 Fig. 18 Photomicrograph showing form of eudialyte i n syenite. 20 F i g . 19 Photograph showing layered form of shonkinite. 21 F i g . 20 Photograph of dark porphyritic layer i n the shonkinite. 22 Fig. 21 Photomicrograph of thin section of shonkinite. 22 F i g . 22 Photograph of composite dyke intruding the porphyritic quartz syenite and hornfels. 2k L i s t of I l l u s t r a t i o n s Figure Page Fi g . 23 Photograph showing intru s i v e contact between leucomonzonite dykes and syenite. 25 F i g . 2I4. Photomicrograph of thi n sections of d i o r i t e dyke showing aligned feldspars and zoned microperthite c r y s t a l s . 26 Fig. 25 Photomicrograph showing myrmekitic intergrowth of f e l d -spar and nepheline. 26 Fi g . 26 Photograph of pegmatitic syenite. 27 Fig. 27 Photograph of t y p i c a l porphyritic quartz monzonite. 28 F i g . 28 Photomicrograph of thi n section of plagioclase crystals showing akeletal areas of microperthite i n quartz monzonite. 28 Fig. 29 Photomicrograph of thi n section showing i r r e g u l a r shaped areas of microperthite i n plagioclase i n quartz monzonite. 28 F i g . 30 Photomicrograph of thin section of border phase quartz monzonite showing minute aggregates of high r e l i e f andra-dite garnet. 30 F i g . 31 Photograph showing abrupt although not intrus i v e , contact between two grain sizes of syenite. 32 F i g . 32 Composition of Garnet 35 F i g . 33 Photograph of x-ray powder d i f f r a c t i o n pattern of garnet i n syenite and i n limestone from contract. 36 Fig. 3k Variation diagram of the oxides of the rocks of the Complex. I42 Table 1 Modal Compositions of the Rock Types 9 1 CHAPTER I A. GENERAL STATEMENT Although s i l i c a deficient igneous complexes represent a small proportion of exposed plutonic rocks, t h e i r genesis i s of considerable i n t e r e s t to geolo-g i s t s . The following report i s the r e s u l t of f i e l d investigations and labora-tory studies of such a complex near Kamloops, B.C. The f i e l d investigations were carried out f o r three weeks i n May I963 and four days i n July 1963. Approximately two hundred specimens were collected. Thirty-two t h i n sections and a few polished sections were examined. B. LOCATION AND ACCESSIBILITY The complex i s located approximately ten miles northeast of Kamloops, B. C. Many roads traverse the area (see f i g . The main ones are the paved road to the Mount Lolo Canadian A i r Force radar base and the gravel road to Paul Lake with i t s extension east to Pinantan Lake and beyond. The area has been extensively logged and there are many convenient, although rough, access roads. C. NATURE OF THE AREA The area i s one of r o l l i n g h i l l s and rounded mountains with elevations ranging from 2800 feet to ££00 feet above sea l e v e l (see f i g . 1). The main outcrops occur on the steep south and west slopes of Mount Fleet and where f i g . 1 View from Summit of Mount Fleet looking southwest. Kamloops i s i n the centre of the photograph. 2 logging operations have exposed bed rock. Unfortunately, a r e l a t i v e l y recently burned area east of Mount Fleet i s now very densely wooded and l i t t l e outcrop was to be found. At lower elevations, e s p e c i a l l y at contacts, the area i s grassland and yellow pine forest with few rock exposures. f i g . 2 View from the Mount Lolo road. Mount Fleet i s i n the centre and Mount Lolo to the l e f t i n the photograph. D. PREVIOUS WORK G. M. Dawson (I898) mentions a syenitic rock near Mount Lolo i n his Shuswap sheet. He also described the Cache Creek rocks i n the Kamloops area. R. A. Daly (1915) also described these Cache Creek rocks. W. L. Uglow (1921) described the Cache Creek rocks of the North Thompson. W. E. Cockfield (19U8) mentioned the rocks of the complex i n his account of the "Coast Intrusions". E. ACKNOWLEDGEMENT The author i s indebted to Dr. K. C. McTaggart of the University of B r i t i s h Columbia who suggested the topic a f t e r his examination of some rock specimens collected by Mr. V. Preto. The help and encouragement of Dr. McTaggart and Dr. R. M. Thompson also of the University of B r i t i s h Columbia, during the study and preparation of the manuscript are greatly appreciated. Special thanks are due Dr. R. B. Campbell i n allowing time for f i e l d investigations during the author's employment with him. Thanks are also due Dr. E. W. Bamber of the Geological Survey of Canada, who i d e n t i f i e d some 3. f o s s i l s from the area, and Mr. J. A. Donnan and Mr. G. E. Montgomery who made the thin sections. u. CHAPTER I I GENERAL GEOLOGY A. REGIONAL SETTING The oldest rocks i n the area ( f i g . belong to the upper Paleozoic Cache Creek group. Cockfield (1°U8) divided the group i n t o the following units: (a) limestone (b) a r g i l l i t e , quartzite, hornstone serpentine, limestone and greenstone and (c) s l i g h t l y sheared greenstone The Nicola group of upper Tr i a s s i c age, contains mainly basaltic volcanic rocks with minor amounts of limestone, a r g i l l i t e and conglomerate. The Jurassic or l a t e r instrusive rocks, i n the general area, are c l a s s i f i e d as "Coast Intrusions" by Cockfield. The Iron Mask batholith of syenite, d i o r i t e , monzonite and gabbro occurs approximately twelve miles southwest of Mount Fleet. Nine miles south of Mount Fleet there are granodiorite and quartz d i o r i t e rocks of the Wild Horse Mountain batholith. There are numerous small granitic stocks and s i l l s northwest of Mount Fleet. In Cretaceous or Tertiary times, andesite, basalt, p i c r i t e , agglomerate, t u f f s and breccias with minor conglomerate and sandstone were l a i d down. The Coldwater beds of miocene or l a t t e r age, were l a i d down next. These rocks of fragmental sedimentary types with associated coal were overlain by the Kamloops group of basaltic volcanic rocks. B. CACHE CREEK GROUP The igneous complex has intruded the rocks of the Cache Creek group. Cockfield (19U8) stated that the rocks of t h i s group i n the general area of Kamloops were "hard dark grey to black argillites....interbedded with CP ' 3 | \ A * ' N G rrV,0l.Q(rY- Cqcl:field ( l 9 4 8 ) Kamloops uroui *) . . - ^ I... 2 Coldwst cv EGd s J .ioccne or a a r l i e r s a l t , b r c c c i a , s s t . e t c . - C r e t . or T e r t i a n /.V'-.v.-.'-. A l Luvium DO GOaet Int rusions - J u r . & l a t e r L i , S i c o l a Gr oup-Tr. Cache Cre ek Grp -limeston e -"breccia , cor.j .etc. i - —sheared greenstone quartzites, and a l i t t l e hornstone, conglomerate and breccias". He finds that associated rocks were dark to l i g h t greenstone, t u f f and agglomerate with discontinuous masses or pods of limestone. The Cache Creek rocks i n the area near Mount Fleet were considered to be basic i n t r u s i v e , extrusive, and fragmental types (Uglow,1922). The rocks immediately around the complex are interbedded green greywacke limestone, volcanic breccia, dark green p h y l l i t e and conglomerate. The fragments i n the conglomerate and volcanic breccia are mainly: a r g i l l i t e , chert, quartzite and green h i g h l y altered volcanic material. The limestone occurs as layered grey beds and as pods which appear to be composed mainly of large angular white limestone fragments. This l a t t e r form i s true of the large outcrop along Paul Lake c a l l e d "Gibraltar Rock" (see f i g . I;). Most of the observed Cache Creek rocks i n the area are green f o l i a t e d greywacke and p h y l l i t e . Their structure can best be seen on the accompanying map ( f i g . 5"). The lack of more extensive data i s due to the lack of outcrop i n the desired areas. The bedding s t r i k e s i n a southeast direction and probably dips steeply (only one bedding attitude observed i n these rocks). A cleavage was developed i n these rocks which strikes i n the same general dire c t i o n as the bedding and dips v e r t i c a l l y . The l a t t e r plane has been disrupted by and now extends around the complex although the bedding appears unaffected. There have been two types of metamorphism operative. A regional one, which was very low grade ( c h l o r i t e zone), i s responsible f o r the cleavage. Within 200 yards of t h e i r contact with the igneous rocks, the Cache Creek rocks have been subjected to contact metamorphism (see f i g . 6). Here the rocks are usually t y p i c a l l y hornfelsic i n appearance and dark green i n 7. colour. In t h i n section, most contain mainly microcline, a l b i t i c plogioclase, dark green b i o t i t e , yellow pleochroic epidote with minor amounts of apatite, magnetite, pyrite, zircon and amphibole (hastingsite). A highly pleochroic tourmaline (schorlite) occurs as short prismatic crystals i n a specimen collected j u s t west of Mount Fleet. A specimen collected on the north-eastern contact contains twenty percent andalusite of the c h i a s t o l i t e variety (see f i g . 7). 5 f i g . 7 Photomicrograph of a X I 4 O thin section of a hornfels specimen showing andalusite. 8 Photomicrograph of thin section of skarn showing garnet (G) and amphibole (A) i n c a l c i t e (C). A skam occurs at the contact northeast of the quartz monzonite intrusion. This rock contained much c a l c i t e , f i n e grained andradite garnet, and deep green amphibole (hastingsite) with minor amounts of magnetite and quartz. No limy contact rock was observed near the s y e n t i t i c intrusions. The 8 . contact metamorphism was low grade, probably i n the albite-epidote hornfels facies. This grade was esp e c i a l l y well displayed by a small incl u s i o n collected near Mount Fleet which contained only green b i o t i t e and epidote as the highest grade of metamorphic mafic minerals. Dr. E. W. Bamber of the Geological Survey of Canada reports that f o s s i l s collected by the author four miles northeast of the west end of Paul Lake (F2 on f i g . 6) are "Pennsylvanian or Permian, probably the former". The follow-i n g f o s s i l s were i d e n t i f i e d : Crinoid Columnals Fenestrate bryozoa Composita sp. Bothrophyllum sp. Caninia sp. The author i d e n t i f i e d c r i n o i d columnals i n a few other outcrops. Part of Complex Porph Sy. Number of Specimen 20 ^ Av (loc a t i o n oij f i g . 6) Quartz 1 2 2 Microcline Microperthite k0 k9 hk K - Feldspar 26 12 18 Plagioclase 25 38 32 Garnet - Andradite T T Pyroxene Aegirine-Augite 8 3 5 Amphibole-Hastingsite - - -Na t r o l i t e -Accessories ( l i s t e d i n decreasing order) Zircon (Z) M M M Apatite (A) S S S Magnetite (M) A E A Epidote (E) E Sphene (S) F l u o r i t e (F) A l l a n i t e (Al) Average An of plagioclase Ang An^ Ang Legend D = S * Sy « T = N = Quartz Sy. 1U1 175 188 Av 3 33 1U 1*2 h 73 22 T 1 7 71 19 T 3 Z M A Z E A M S A A n 1 Q A n 1 Q 5 59 5 27 T 3 1 Z A M E A n 1 2 A n ^ s i TABLE 1 MODAL ANALYSES OF PLUTONIC ROCKS • v i i a i n S y e n i t i c Intrusion ^Syenite N.Sy. Shonkinite * :* 59 86 1UU 165 186 Av 196 168 171 96 117 Av _ - - - - - 3- - -6U 72 76 63 69 58 63 26 57 72 65 - — - - 1 T - - - 1 - 5 l U 13 20 15 33 18 36 7 5 25 1 13 % 8 5 - 1 U 1 15 36 1 10 5 11 8 3 5 1 6 5 15 32 8 3 5 7 - U - 2 - 2 - - - -\l - - - - 1 - 2 mm 8 l U 11 •\ .;M . A s M z M z z z Z s z ;Z z z z s z s s s s z s S A s s M A A E A A M A A A E - E E A n 1 G Any An^ A n 1 Q A n 1 0 Aria Ang An 8 Any A n i 5 A n u Ar Nat. Sy. dykes shonkinite • syenite t r a ce t^v* *. small northern syenitic i n t r u s i o n i'f& Notes - The percentage of a l t e r a t i o n products was added to the appropriate mineral they replace. m m 56 10 1 $ i f mi--:-Sy. 2 OB Dior Monz 178 1 8 U 50 31 27 u 19 20 2U 37 50 - 7 1 15 5 2 Quartz Monzonite Intrusion I n t e r i o r Phase Border Phase 17 50 1 31 2? 19 2U 63 Av 13 70 Av 3 l U 29 31 30 27 37 30 38 3U -.5 1 - .5 13 U7 38 30 3^ 57 T T T 3 2? 1? 1.5 3 .A z Z F F F F F F F _z S S Ai A' A Ai M A Z -S M A M Z M Z A M M _M A E M Z Z _E • A A - E A n 1 2 A n 1 0 An u An 8 Ang Ang A n l l A n 1 Q A n 1 0 A n 1 Q 10. CHAPTER I I I GEOLOGY OF THE IGNEOUS COMPLEX A. GENERAL STATEMENT The complex has a t o t a l area of about twenty-five square miles. The three bodies which comprise the complex include a small syenitic intrusion (1.7 by 5 miles) which l i e s j u s t north of a large s y e n i t i c intrusion (7 by 3 miles). To the south, a Quartz Monzonite intrusion outcrops (2.5 by 2.5 miles). The small northern intrusion i s apparently composed only of syenite. The main syenitic i n t r u s i o n i s composed, from the contact to the middle of: quartz syenite, syenite and n a t r o l i t e "nepheline" syenite. The quartz syenite i s porphyritic when found at the contact. Shonkinite occurs i n two areas of mafic r i c h syenite near the top of Mount F l e e t (see f i g . 6). Various dyke rocks were found throughout the syenitic units. The quartz monzonite intrusion has a " c h i l l e d " fine-grained border and, commonly, a porphyritic coarse grained centre. A p l i t i c dykes cut both of these rock types. The rocks w i l l be described i n this general order. The modal percentages of minerals i n various igneous rocks are shown i n the accompanying table ( l ) . B. ROCK TYPES 1. Porphyritic quartz syenite. The prophyritic quartz syenite i s found i n scattered areas near the contact with the Cache Creek rocks, as dykes i n the metamorphic aureole, and r a r e l y as scattered inclusions i n the syenite. In hand specimen i t contains approximately twenty percent of large (to 3 cm. long) w e l l oriented phenocrysts of pinkish or grey a l k a l i f e l d -spar i n a fine-grained grey groundmass. In thi n section, the rock i s seen to contain large microcline-rich [\J P,, v TOFUGitAPHY AND OUTCROP Contours Streams-^ 1 mile itoads- S Outcrop-F-,, ? STRUCTURAL GEOLOGY F o l i a t i o n of f e l d s p a r p l a t e s — / 2,dipplng / v e r t i c a l T r e n d s - — — • f, P o l i & t i o n of Cache Creek r o c k s - — ^ v e r t i c a l -F o l i a t i o n of Cache Creek r o c k s ( i n t e r p r e t e d ) - / / Centers of con c e n t r i c patterns — Y,X 0« b y ^ r i t l e ; . o c . 1" •  o s  I | Ie;.r than 5$ lies*) 1 ' 5 to 15p mafics ( ,.Vo.nn-u.,., 15 to 25% mafics J * 1 j h o n l c i n i t e ( r r c f . t o r than 25/') Uuartz Koiizonite a t r o l i t e Syenite Border phase O.ohc Creole r o c k s Ifornfels >r' i' •! Lino: b e I v o l s © l v •; i l o c a l / equi.-/rrr.ul: r ( c . g . \ quartz p o r p h y r i n i c j oyeniti Types 'le l o c a l r o r p h y n t i c i n t e r i o r phase r; ywacke,breccia,shale,;.r w i l l i t e Probable igneous contact contact bv Coekfield(1S48) *°© J;.;..nle w i t h t h i n s <>0o._ r£e h o r n f e l s b l o c k s ' / Cont, section' 1 o s s i b l e c o n t a c t 1U. (microcline greater than eighty percent) euhedral to subhedral microperthite crystals containing widely spaced a l b i t i c lamellae. Many of the grains are multiply zoned showing successive layers of microperthite and plagioclase ( f i g . 9 ) . f i g . 9 Photomicrograph of a t h i n XliO section of porphyritic quartz syenite showing the porphyritic texture of the rock and a zoned feldspar (dark zones i n the feldspar are micro-perthite, white zones are plagroclase). The refractive index of the very th i n plagioclase zones appeared to increase s l i g h t l y from the core outward. Rarely, ragged areas of micro-perthite are found i n large plagioclase grains. The lamellae of plagioclase i n these areas are o p t i c a l l y s i m i l a r to those i n the rest of the grain. Microperthite was found as wide mantles around large highly altered plagio-clase grains. Embayments and fractures i n the phenocrysts are f i l l e d with a mosaic groundmass. Euhedral aegirine-augite, zircon, sphene, magnetite with exsolved hematite and anhedral microcline and a l b i t i c plagioclase grains are r e s t r i c t e d to the peripheral areas. Such inclu s i o n - charged feldspars are t y p i c a l of a l l the syenitic rocks. Aegirine-augite, zircon (occasionally zoned) sphene, apatite and magnetite with exsolved hematite occur generally euhedral i n form and between the feldspar phenocrysts. The a p l i t i c groundmass i s composed of plagioclase (Ang to An 1 0) i n t e r -grown with twinned microcline grains, fine-grained aggregates of l i g h t yellow anhedral garnet ( i n one specimen) and quartz. The i n t e r s t i t i a l quartz occurs 15 as minute anhedral crystals and as large clear grains bounded by very small low birefringent radiating "bursts" of unidentified z e o l i t e . This zeolite also occurs i n minor amounts throughout the groundmass. Deuteric a l t e r a t i o n i s shown by c h l o r i t e , pleochroic yellow epidote, and c a l c i t e replacing pyroxene. The feldspar phenocrysts were observed to be mildly s e r i c i t i z e d . 2. Quartz syenite Quartz syenite occurs mainly i n the northern part of the large syenitic intrusion (see f i g . 6). I t appears to be the coarse grained equivalent of porphyritic quartz syenite. In hand specimen, the rock i s seen to contain large stubby feldspar crystals with an even scattering of fine-grained mafic minerals. f i g . 10 Photograph of a hand specimen of quartz syenite Large grains of amphibole were observed i n some specimens. Quartz was d i f f i c u l t to i d e n t i f y . In t h i n section the subhedral feldspars were observed to be l i k e the phenocrysts i n the porphyritic quartz syenite except for the former's stubbier form. Many of the feldspars contain discontinuous cores of oligoclase (AIVJQ) (see f i g . 11). 16. f i g . 11 Photomicrograph of o p t i c a l l y Xlj.0 discontinuous oligoclase core of microperthite c r y s t a l i n quartz syenite Plagioclase (An-^ Q. - Anjjg) commonly contains ragged areas of microperthite. Garnet, which i s present i n nearly a l l the s y e n i t i c rocks, i s absent i n these. The aggregates of amphibole mineral were i d e n t i f i e d as hastingsite by i t s 2V of 20° (-3° ), low birefringence, and pleochroic scheme X Y Z pale brownish green brown green dark blue green The amphibole appears i d e n t i c a l to one from Kruger Mountain i d e n t i f i e d by Campbell (1939). Large clear quartz grains were found i n t e r s t i t i a l l y . Aegirine-augite, apatite, zircon, sphene and much opaque material are present i n euhedral form. The groundmass, forming ten percent of the rock, i s composed of micro-c l i n e and mainly plagioclase (Ang). Plagioclase occurs as p a r t i a l rims on large microperthite c r y s t a l s . The mafic minerals are unaltered but the feldspars are s l i g h t l y s e r i c i t i z e d . 3. Syenite The main rock type i s syenite with varying amounts of mafic minerals (see f i g . 6). This rock appears to be the only type i n the northern int r u s i o n . In hand specimen, the pinkish white colour of the feldspars near Mount Fleet corresponds to a higher content of mafic minerals i n the rocks i n this area. The feldspar laths elsewhere are generally grey. The rock 17. i s composed mostly of these aligned feldspars. The alignment may be i n one direction ( f i g . 12) or i n s w i r l - l i k e orientation ( f i g . 13). Dodecahedral garnet and prismatic bright green pyroxene crystals are also v i s i b l e i n the hand specimens. There i s a great variation i n grain size i n this rock. In t h i n section, the rock was seen to consist mostly of microcline microperthite-plagioclase (Any to An-^ ) intergrowths which are s i m i l a r to those i n the quartz syenite. f i g . 12 Photograph of w e l l aligned feldspar laths i n syenite (from road cut on Mount Lolo) 4 f i g . 13 Photograph of s w i r l -l i k e orientation of feldspar laths i n syenite (same l o c a l as f i g . 12) 18. In one specimen there are both plagioclase crystals with hourglass-texture and e l l i p s o i d a l microperthite feldspars. The hourglass texture consists of microcline microperthite i n hourglass form i n plagioclase ( f i g . 15). f i g . 15 Photomicrograph of hour-XUO glass textured feldspars i n syenite. Plagioclase = P Microperthie • M The e l l i p s o i d a l feldspars are zoned s i m i l a r l y to the other micro-perthite intergrowths but thei r form has apparently no r e l a t i o n to the zoning. The e l l i p s o i d s show rounded embayments. Rarely, plagioclase apparently i s replaced by anhedral andradite garnet ( f i g . 16). The garnet also occurs as i n t e r s t i t i a l aggregates and as larger enhedral c r y s t a l s . Amphibole, similar to that i n the quartz syenite has replaced euhedral aegirine-augite ( f i g . 17) and also forms i r r e g u l a r masses. 19 XLO (b) crossed nicols X I 4 O (a) p l a i n l i g h t f i g . 16 Photomicrograph showing plagioclase p a r t i a l l y replaced by garnet (G). Note that the feldspar twin lamellae i n (b) continue on other side of i s o t r o p i c garnet mass. 4 f i g . 17 Photomicrograph showing amphibole (with cleavages %i" at 60° and dark) apparently replacing aegirine-augite(cleavages at 90° and l i g h t e r ) 20. Subhedral green b i o t i t e occurs i n one specimen. Zircon, sphene, opaques and zoned apatite, which were also observed, are a l l euhedral i n form. A few small equant pink grains v i s i b l e i n hand specimen were i d e n t i f i e d as eudialyte i n the thin section on the basis of colour, zonal, u n i a x i a l positive and low to moderate birefringence. f i g . 18 Photomicrograph I.U.0 showing form of eudialyte i n syenite E= Eudialyte G» Garnet F« Feldspar P= Pyroxene Irregular i n t e r s t i t i a l masses of pyrrhotite and chalcopyrite with the a l t e r a t i o n product malachite are r a r e l y seen. The groundmass i s s i m i l a r to that i n the quartz syenite. Secondary epidote has, i n places, replaced plagioclase and c h l o r i t e with limonite haveyreplaced some of the pyroxene. Most of the feldspar crystals show mild s e r i c i t i z a t i o n . U. Natrolite "nepheline" syenite This rock i s found mainly near the middle of the i n t r u s i o n . In hand specimen, i t i s distinguished from syenite by i t s r e l a t i v e l y high content of n a t r o l i t e . In t h i n section, n a t r o l i t e occurs between the unaltered feldspar laths as radiating aggregates occuring i n places i n squarish outlines. The natro-l i t e was i d e n t i f i e d by i t s x-ray powder d i f f r a c t i o n pattern and o p t i c a l properties. In one specimen, a minor amount of cancrinite appears to have 21. been l a r g e l y replaced by n a t r o l i t e . The form and occurrence of n a t r o l i t e suggests i t i s formed from pre-existing nepheline. Very minor amounts of altered nepheline were observed i n the n a t r o l i t e . 5. Shonkinite Shonkinite occurs i n only two l o c a l i t i e s both i n mafic r i c h rocks near Mount Fleet (see f i g . 6). I t s f l o a t i s abundant i n this area. I t i s to be noted that the shonkinite (and the mafic r i c h rocks) are on strike with the largest limestone layer which outcrops at Paul Lake. In hand specimen, the rock i s composed of alternating layers of mafic and s a l i c material. These layers are commonly about f i v e centimeters thick and p a r a l l e l to the feldspar alignment (see f i g . 19 and f i g . 20). The shonkinite appears to be contained as lenses within mafic-rich syenite. The mafic-rich layers contain mainly dark brown euhedral dodecahedral garnets (to 5 cm. i n diameter), stubby pyroxene prisms and large a l k a l i feldspar phenocrysts. f i g . 19 Photograph showing layered form of shonkinite 22. f i g . 20 Photograph of dark porphyritic layer i n the shonkinite f i g . 21 Photomicrograph of t h i n section of shonkinite showing zoned garnets, inclusions i n garnets (with crossed nicols) and general texture of the rock. G= Garnets A= Aegirine-augite In thin section, the rock i s seen to consist l a r g e l y of euhedral zoned andradite garnet and euhedral prismatic crystals of green pleochroic 23. aegirine-augite. The garnet commonly contains concentrically arranged zircon, sphene and aegirine-augite crystals of euhedral form. A few of the garnets are i r r e g u l a r l y anisotropic with areas of low birefringence and an apparent high 2V. Garnet was seen i n places as euhedral c r y s t a l s i n some of the microperthite grains and r a r e l y as anhedral masses i n t e r s t i t i a l to the micro-perthite. Some aegirine-augite contains w e l l defined non pleochroic cores (diopsidic) having extinction d i f f e r e n t from that of the large outer rims. Feldspar phenocrysts show textures s i m i l a r to those of a l l the syenitic rocks but contain l i t t l e included material. These rounded cr y s t a l s show some embayments and large fractures f i l l e d with mainly anhedral plagioclase. Large grains of apatite and zircon with minor amounts of large sphene grains occur around the garnet and smaller ones within the garnet. The ground mass consists of microperthite, plagioclase (Any) and very minor amounts of microcline. The plagioclase which makes up most of the groundmass i s found as p a r t i a l rims on the large microperthite c r y s t a l s . No opaque minerals were observed. The mafic minerals are not altered but the feldspars are mildly s e r i c i -t i z e d . A very minor amount of i n t e r s t i t i a l n a t r o l i t e was observed. 6. Dyke rocks (a) Porphyritic syenite dykes A few r e l a t i v e l y wide ( i n places to twenty feet) dykes of porphyritic quartz syenite have intruded the Cache Creek rocks at oblique angles to the l a t t e r ' s f o l i a t i o n . The dykes have no recognized regular attitudes. They contain numerous e l l i p s o i d a l xenoliths which are oriented with t h e i r longest axes p a r a l l e l to the walls of the dyke. (b) Syenite dykes A few examples were observed of composite dykes consisting of a d i s t i n c t coarse grained inner-("20a" i n table l ) and a f i n e r grained outer 2U. ("20b" i n table 1) dyke (see f i g . 22) f i g . 22 Photograph of composite dyke intruding the porphyritic quartz syenite (right) and hornfels ( l e f t ) . Note the orientation of the pyroxene and feldspar which are elongate normal to the walls. Their attitudes were highly varied and they were found a l l around the edges of the syenitic intrusions. As can be seen ( f i g . 22), the dyke shows a clear d i l a t i o n offset. The dyke rock appeared similar i n hand specimen to the syenite. The e a s i l y recog-nizable pyroxene and a l k a l i feldspar crystals have t h e i r longest dimensions normal to the walls. In thin section, the rock i s s i m i l a r to the syenite except for "the lack of garnet and the occurrence of p y r i t e . The outer dyke contains much plagio-clase and a minor amount of microcline i n the groundmass but the inner dyke has only a very minor amount of i n t e r s t i t i a l plagioclase. The apatite, i n the outer dyke, i s concentrated as small anhedral grains at the hornfels con-tact but i n the inner dyke i t occurs as large grains scattered throughout with the pyroxene. The pyroxene i n the outer dyke appears to be aegirine while that i n the inner dyke i s aegirine-augite. Some areas along the contact of the outer dyke show a c h i l l e d zone of unaltered plagioclase and microcline. The lack of exsolved plagioclase i n the mincrocline w i l l be discussed under "Feldspars". The f a c t that they have intruded the outer quartz syenite and t h e i r similar composition suggest they were formed during the c r y s t a l l i z a t i o n of 25. the inner syenite. (c) Leuco monzonite dyke There are numerous intrusive a p l i t i c dyklets of leuco monzonite i n the southwestern area. The attitudes of these dykes vary greatly. They contain fragments of syenite, the feldspar alignment of which d i f f e r from the syenite which makes up the wall rock. This shows rotation of these fragments. In thin section the rock i s composed mainly of an a p l i t i c intergrowth of microcline and plagioclase (Anj^ ). Apatite, zircon, and large aegirine-augite grains were a l l auhedral. Garnet occurs mainly i n i n t e r s t i t i a l aggregates of anhedral crystals that apparently replace plagioclase. (d) Diorite dyke A two foot wide d i o r i t e dyke was found to the southeast of Mount Lolo. I t apparently was intruded p a r a l l e l to the f o l i a t i o n of the syenite. In hand specimen, the fine grained rock i s darker colored than the syenite i t has intruded. I t appears to consist of occasional feldspar phenocrysts with some mafic minerals i n a very f i n e grained grey groundmass. f i g . 23 Photograph showing int r u s i v e contact between leucomonzonite dykes and syenite. 26. In th i n section, i t i s composed mainly of extremely w e l l f o l i a t e d plagioclase (Ang ) laths which "swell" around occasional stubby, simply zoned microcline microperthite phenocrysts ( f i g . 2U). The plagioclase occurs as f a i r l y small twinned laths. The microperthite i s s i m i l a r to that i n the rest of the intrusion except f o r i t s zonal character. The successive (usually three) zones have a decreasing refractive index from the centre of the c r y s t a l to the edge. Between the laths there were "knots" made up of small crystals of euhedral aegirine-augite, garnet, magnetite and anhedral green b i o t i t e . Euhedral sphene and zircon are scattered throughout. There are very small grains of an odd myrmekitic intergrowth (see f i g . 25), i d e n t i c a l to one shown by Johannsen (1939, p.UU) having approximately the re f r a c t i v e index of nepheline and potash feldspar and intimately associated with cancrinite. The fine grain size makes positive i d e n t i f i c a t i o n impossible but i t i s believed to be an intergrowth of nepheline and potash feldspar, 27. (e) Pegmatitic syenite dykes There are rare occurrences, commonly near Mount Fleet, of coarse grained pegmatitic syenite dykes ( f i g . 26). Ninety-five percent of this rock appears to be composed of microcline microperthite crystals some of which are s i x centimeters long. The contact between this rock and the adjacent syenite i s sharp. The pegmatitic syenite i s a c r y s t a l accumulate or the product of c r y s t a l l i z a t i o n from a v o l a t i l e r i c h magma. C. THE QUARTZ MONZONITE INTRUSION The northern contact of the quartz monzonite in t r u s i o n i s situated 100 yards south of the main syenitic intrusion (see f i g . 6). The intrusion consists of a generally porphyritic i n t e r i o r phase, a c h i l l e d border phase and numerous d i o r i t e dykes. 1. Interior porphyritic phase - Quartz Monzonite This phase of the quartz monzonite i s the dominant rock type (see f i g . 6). The highly weathered rock shows, i n hand specimen, about twenty-f i v e percent large white potash feldspar phenocrysts having pinkish rims (see f i g . 2). Small equant areas are composed of c a l c i t e , limonite and ch l o r i t e . These areas of secondary minerals were seen to be pseudomorphs af t e r green pyroxene. f i g . 26 Photograph of pegmatitic syenite. 23. f i g . 2 7 Photograph of t y p i c a l porphyritic quarts monzonite. The fine grained ground mass i s mainly plagioclase. In thin section, the rock contains microcline microperthite as: phenocrysts, i n scattered irregular and skeletal areas i n plagioclase and as some of the i n t e r s t i t i a l grains of the groundmass. 29 Photomicrograph of thin section snowing irregular shaped areas of micro-perthite (dark) in plagio-clase (white) i n quartz monzonite. 29. The microcline microperthite contains up to twenty percent exsolved plagio-clase. Some of the large (to 2 cm. long) microperthite grains, which were freed by weathering, appear to show a monoclinic form which would suggest that inversion to t r i c l i n i c microcline from monoclinic orthoclase. The pink-i s h rims seen i n hand specimen ( f i g . 27) were not observed i n the thin sections. The microcline microperthite phenocrysts contained concentrically arranged plagioclase inclusions. These plagioclase inclusions (Ang ) are euhedral but those which constitute most of the rock are subhedral. The bulk composition of the apparently unzoned plagioclase which constitutes most of the rock i s Ang. The plagioclase not found as inclusions generally contains i r r e g u l a r ( f i g . 29) and skeletal ( f i g . 28) areas of microperthite. The apparent micro-cli n e content of the plagioclase may be as high as ninety percent or as low as ten percent. Very small amounts were observed of euhedral grains of apatite, zircon, magnetite and a l l a n i t e . The a l l a n i t e was i d e n t i f i e d mainly by i t s high positive r e l i e f f a i n t yellow pleochroism, zonal character and metamict state. F l u o r i t e , which occurs i n r e l a t i v e l y large amounts (three percent) was i d e n t i -f i e d by i t s diagnostic o p t i c a l properties and x-ray powder d i f f r a c t i o n pattern. I t i s anhedral i n form, commonly f i l l i n g fractures i n a l l the rocks of the quartz monzonite intrusion. Weakly pleochroic diopsidic aegirine-augite was found as unaltered grains i n only one specimen. In most specimens i t had been altered to limonite, c a l c i t e , minor c h l o r i t e and fine grained yellow pleochroic epidote. The l a s t mineral also has replaced plagioclase. The plagioclase and e s p e c i a l l y the microcline have been s e r i c i t i z e d . A minor amount of cataclasis of the feldspars was noted. 30. 2. Border phase - Quartz Monzonite i n t r u s i o n The c h i l l e d fine grained, border phase of the quartz monzonite i n t r u s i o n i s found within about one hundred yards of the quartz monzonite-hornfels con-tact (see f i g . 6). The contact between i t and the i n t e r i o r phase appears to be gradational. The pink rock, i n hand specimen, i s fine grained. Some sheared areas were noted i n the hand specimen. The few mafic minerals o r i g i n a l l y present have been completely altered. In thin section, i t i s nearly i d e n t i c a l i n composition to the matrix of the porphyry of the i n t e r i o r phase. There i s also a somewhat higher content of potash feldspar and f l u o r i t e with traces of yellow andradite garnet. f i g . 30 Photomicrograph of t h i n XI4OO section of border phase quartz monzonite show-ing minute aggregates of high r e l i e f andradite garnet. The rock has been subjected to more cataclasis than the i n t e r i o r phase. 3. Quartz d i o r i t e dykes Many quartz d i o r i t e dykes have intruded both the c h i l l e d border and the i n t e r i o r phase of the quartz monzonite intrusion. There does not appear to be a p a r t i c u l a r pattern to the attitudes of these dykes. In hand specimen, the rock i s a p l i t i c i n appearance with a scattering of minute grains of mafic minerals. In th i n section i t shows a t y p i c a l a p l i t i c intergrowth of arihedral unaltered microcline, plagioclase (An-,n) and quartz. A pleochroic pyroxene, 31. probably aegirine, and anhedral f l u o r i t e are r e l a t i v e l y common constituents. Euhedral magnetite and zircon with anhedral apatite and some small grains of i n t e r s t i t i a l yellow garnet are present i n very minor amounts. D. SIMILARITIES AND DIFFERENCES OF THE SYENITIC AND QUARTZ MONZONITE INTRUSIONS S i m i l a r i t i e s (1) The margins of both show pronounced deflection of the secondary cleavage of the Cache Creek rocks. (2) They occur almost i n contact but the nearest other exposed pluton i s many miles away. (3) Both bodies contain aegirine-augite, zircon, a l b i t i c plagioclase, garnet and s i m i l a r microcline microperthite. (k) Both rock types, e s p e c i a l l y the s y e n i t i c ones, are poor i n quartz. Differences Quartz Monzonite Intrusion Syenitic Intrusions Inclusions Fabric Alignment Dykes i n igneous rocks Dykes i n adjacent rocks Intrusive textures Mineralogy A l t e r a t i o n of mafics very few observed none apparent many a p l i t i c textured quartz monzonite dykes very minor amounts of small border phase quartz monzonite dykes some shearing at the border a l l a n i t e and much f l u o r i t e nearly completely altered to mainly limonite and c a l c i t e many; both porphy-r i t i c syenite and "country" rock. feldspar laths are w e l l aligned 3 very few-syenite many small to large of commonly porphy-r i t i c syenite no mechanical defor-mation a l l a n i t e and f l u o -r i t e are absent mafics mainly unaltered some . a l t e r a t i o n to amphibole E. STRUCTURE Internal 32. The contacts between the various units i n the syenitic intrusions and the two i n the quartz monzonite are gradational. In the s y e n i t i c intrusions there are, i n places, concentrations of large feldspar laths probably con-centrated by c r y s t a l accumation. The contact between these and the f i n e r -grained syenite i s abrupt although coarse crystals (phenocrysts) occur i n the l a t t e r (see f i g . 31). The dykes both the syenite and the quartz monzonite show sharp con-tacts. Some of those i n the large syenitic intrusion show d i l a t i o n offsets The quartz monzonite intrusion i s composed of equant minerals and therefore there are no apparent i n t e r n a l flow structures. The syenitic rocks contain aligned p l a t e - l i k e feldspar c r y s t a l s . The pattern of the alignment of these feldspars i s best shown i n figure £. In general, i t i s p a r a l l e l to the contact of the stock. The alignment of these unfractured feldspar laths do, to the author, s i g n i f y preferred orientation caused by flow of a mainly f l u i d magma. In general, there were two patterns of concentric feldspar alignment, one with i t s centre approximately two-thirds of a mile north (X of f i g . 5) and the other two miles northeast (Y of f i g . 5) of the summit of Mount Fleet. This flow may have been by the r i s e of a p a r t l y c r y s t a l l i n e magma. This indicated uninterrupted flow ( f i g . 12) or some s w i r l - l i k e orientations ( f i g . 13) which f i g . 31 Photograph showing abrupt although not int r u s i v e , contact between two grain sizes of syenite. (e.g. f i g . 22). 33. suggest there were "eddy currents". External As mentioned i n the description of the Cache Creek rocks, the f o l i a t i o n of the country rocks generally extends around the intrusions (see f i g . In some areas the f o l i a t i o n had been truncated by the intrusions. These general features suggest the plutons were emplaced by mainly wedging t h e i r way in t o the Cache Creek rocks. Large blocks of hornfels near the igneous-metamorphic contact and smaller inclusions are scattered throughout the syenitic bodies. Few blocks were observed i n the quartz monzonite but th i s pluton i s not very w e l l exposed. I t appears that some piecemeal stoping has taken place. 3U. CHAPTER IV DESCRIPTIVE MINERALOGY A. AEGIRINE-AUGITE This mineral i s a constant and major constituent of the syenitic rocks. I t occurs i n minor amounts i n the quartz monzonite. This mineral has c r y s t a l l i z e d e a r l y (before the garnet and the feldspars). In the syenitic rocks, some of i t shows a nearly non-pieochroic w e l l defined central zone s i m i l a r to the pyroxene i n the quartz monzonite. A sample of mafic syenite f l o a t found j u s t west of Mount Fleet contain aegirine-augite with a central zone of what appears to be clear, anhedral o l i v i n e . The proper-t i e s of this l a t t e r mineral are 2V=8S> , o p t i c a l l y negative, moderate b i r e -fringence and lack of cleavage. This would indicate the d i o p s i t i c pyroxene and o l i v i n e were l o c i of aegirine-augite c r y s t a l l i z a t i o n . Some aegirine-augite crystals have analteration rim of green amphibole (see f i g . 17). These suggest a lower pressure and temperature with a somewhat higher concen-t r a t i o n of water near the end of c r y s t a l l i z a t i o n . B. ANDRADITE GARNET This mineral i s found i n the syenitic quartz monzonite and skarn rocks. In the syenitic rocks i t probably c r y s t a l l i z e d during or a f t e r the pyroxene as i t was observed containing euhedral pyroxene. I t probably entered the pluton a f t e r intrusion of the quartz syenites as no euhedral garnet was found i n these rocks. The suhedral garnet was determined by measurement of ref r a c t i v e index, c e l l edge (from x-ray d i f f r a c t i o n photographs) and s p e c i f i c gravity, from samples of widely scattered points i n the large syenitic intrusion, to be nearly pure andradite (see f i g . 32). I t occurs as aggregates of anhedral crystals i n some of the quartz monzonite ( f i g . 30) and sye n i t i c rocks; and apparently replaced plagioclase i n some syenitic specimens, ( f i g . 16) The garnet i s found as euhedral inclusions i n the microperthite and sparsely as 35. anhedral i n t e r s t i t i a l masses between the grains. The evidence would suggest that there were at l e a s t two periods of garnet growth, one forming euhedral cry s t a l s early during or before c r y s t a l l i z a t i o n and at lea s t one other, near the end of c r y s t a l l i z a t i o n which forms anhedral masses and replacements i n plagioclase. In general, where much garnet occurs there i s l i t t l e or no magnetite. A skarn mentioned i n the section on Cache Creek rocks, contains andradite garnet with i d e n t i c a l x-ray pattern to that i n the main intrusion (see f i g . 33). The garnet i n the syenite could have been formed i n the following ways: 1. by metasomatic replacement by garnet of minerals of the syenite. 2. as xenocrysts derived from a skarn. 3. by c r y s t a l l i z a t i o n d i r e c t l y from the magma. 1. Some of the garnet i n the syenite shows i t has replaced plagioclase ( f i g . 16). This type of replacement forms anhedral not euhedral garnet. The aggregates of i n t e r s t i t i a l anhedral garnets i n the syenite and the quartz monzonite ( f i g . 30) are believed to have formed by replacement si m i l a r to that which replaced the plagioclase. The o r i g i n of concentrically arranged zircon and sphene i n the euhedral garnets, which form the bulk of the garnets i n the syenitic rocks, i s d i f f i c u l t to explain by replacement. v ^ n i i k e { Cc ft) f i g . 33 Photograph of x-ray powder d i f f r a c t i o n pattern of garnet i n syenite (a) and i n limestone from contact (b). The shonkinite i s layered i n form and the supposed garnet replacement would have to occur here i n layers. The other syenite does not have such layered structures which could be replaced. In general, the author does not believe that replacement of the minerals (e.g. plagioclase) i n the syenite by garnet i s the mechanism by which most the garnet formed. 2. The Garnets could have been formed i n the limestone layers (forming a skarn) l i k e those observed i n the contact limestone. The skarn could have been stoped away and subsequent melting of parts of the rock could have freed the garnet. The fact that andradite garnet was found i n both a skarn at a contact (with the quartz monzonite intrusion) and as a main constituent of the s y e n i t i c intrusions would be evidence f o r this hypothesis. The high concentration of garnets d i r e c t l y on s t r i k e with the large limestone layer seen at "Gibraltar Rock", would also be evidence f o r this hypothesis. Wright (1938) reports that andradite garnet i n ninety percent of occurrences i s i n skarns. This would also favor o r i g i n of the garnets at Mount Fleet from a skarn. There are, however, certain problems with t h i s manner of o r i g i n . I t i s true that a skarn was found which contained andradite, but the garnets were small, anhedral and free of inclusions. No zircon, 37. sphene, apatite or aegirine-augite were observed i n this skarn. This was, however, i n only one example. I t i s not certain that other skarns do not have zircon. The high concentration of concentrically arranged zircon and sphene i n a skarn-derived garnet i s not common. The author has observed limestones, which contain abundant zircon, apparently near the contact of a zircon bear-ing nepheline syenite at Lempriere, B.C. However, the author does not know of a si m i l a r l o c a l . I t i s possible that some zircon, sphene, apatite and aegirine-augite were formed i n a skarn at Mount Fleet and garnet formed, including these minerals. Unfortunately l i t t l e skarn was observed and none at the contact of the syenitic rocks. The garnet has inclusions of aegirine-augite which i n thi n section are i d e n t i c a l to those i n the intrusions. The enhedral form of this type of inclusion, and the other euhedral inclusions, suggest i t formed before the garnet. I t i s true that aegirine-augite has been reported to have formed metasomatically i n contact rocks (e.g. fenites) but at Mount Fleet the zircon, apatite and sphene inclusions would also have to form there. As the i n c l u s -ions are i d e n t i c a l to the same minerals not occurring as inclusions i t would indicate they had a common or i g i n . However, th i s would mean that the syenite had a few mafic constituents (they apparently were a l l formed i n the skarn), which i s incompatable with the fact that syenites usually contain many. The origin of the garnets by t h i s hypothesis seems possible although spec i a l conditions are necessary. 3. Andradite garnet could have c r y s t a l l i z e d d i r e c t l y from the syenitic melt. Andradite garnet has been described i n syenitic rocks by many authors (Campbell, 1939; Krauskopf, 19Ul; Shand, 1952; etc) but the o r i g i n of the garnet has not been considered. The intimate association of garnet with aegirine-augite, zircon, apatite and sphene, which are considered common magmatic minerals i n syenites (Winchell, 1952) would suggest that the garnet too i s magmatic. 38. The o r i g i n of garnet by c r y s t a l l i z a t i o n from a magma was suggested i n 1910 by Daly. The reason andradite garnet has not been formed i n the labora-tory by c r y s t a l l i z a t i o n from a melt i s not known. Spessartite garnets, how-ever, are found i n granites and granite pegmatites and did apparently c r y s t a l -l i z e from magmas. The laboratory experimentation may be incomplete but assuming i t i s not, the following may be possible. Ninety f i v e percent of a l k a l i c rocks are associated with limestone (Shand, 1952) and the in t r u s i o n of such a plutonic rock would very l i k e l y form andradite garnet with adjacent skarn. I f a fin e grained skarn were to be assimilated the garnet crystals would possibly survive and form nuclei f o r c r y s t a l l i z a t i o n of additional andradite. That c r y s t a l growth can be induced by seeding of crystals i s w e l l known (Buckley, 1951) and the limestones at Mount Fleet have small anhedral grains of andra-d i t e garnet i n them. A few ir r e g u l a r shaped cores appeared to be present i n some thin sections but the chance of cutting exactly through the centre of the garnet when making thin sections i s small. The o r i g i n of the garnets by c r y s t a l l i z a t i o n from the syenitic melt seems, to the author, the most probable. In summary, garnet was found i n the contact limestone, s y e n i t i c i n t r u -sions and to a minor extent i n the quartz monzonite intrusion. I t i s not known whether most of the garnet formed i n the contact limestone or c r y s t a l -l i z e d d i r e c t l y from the melt. Either method would deplete the magma of available s i l i c a . The author favors the l a t t e r o r i g i n . C. FELDSPARS Feldspars are very abundant i n the complex and occur i n two forms. Near the contacts with the Cache Creek rocks they generally form mosaic intergrowths ( f i g . 9) of mainly a l b i t e and microcline. These constituents show no apparent exsolution. Most of the feldspars i n the i n t r u s i o n form crystals with extensive exsolution. There are three d i s t i n c t stages of 39. c r y s t a l l i z a t i o n of these l a t t e r feldspars. These are chronologically: ( i ) oligoclase plagioclase, ( i i ) microperthite, and ( i i i ) rims of a l b i t i c plagioclase. ( i ) The f i r s t stage of th i s feldspar c r y s t a l l i z a t i o n was that of stubby crystals of oligoclase (A^ Q) plagioclase which occasionally form cores i n the micro perthite grains (see f i g . 11). This texture i s not uncommon for crystals formed by f r a c t i o n a l c r y s t a l l i z a t i o n of melts of the syenitic compos-i t i o n (Tuttle and Bowen, pp. 133-13U). The corroded plagioclase cores represent crystals which did not completely react with the l i q u i d and subse-quently potassic feldspar c r y s t a l l i z e d apparently used them as l o c i of c r y s t a l -l i z a t i o n . The texture has been observed by many petrologists (Tuttle and Bowen, 1958) f o r example Buddington (1939) states: "Feldspar forms i n general seventy to seventy nine percent of the rock and consists of a core of plagioclase surrounded by a zone of microcline." ( i i ) The second stage of th i s type of feldspar c r y s t a l l i z a t i o n i s that of microcline microperthite and a l b i t i c plagioclase which may form oddly zoned c r y s t a l s . The exact composition of these cr y s t a l s can only be determined by chemical analysis and consideration of the (201) spacing of x-ray films, with the position of the optic axis and the optic angle known (Tuttle, 1962). The microscopically t h i n zones (see f i g . 9) of microperthite make extraction f o r x-ray study p r a c t i c a l l y impossible. The optic angle of 80° was determined (by U-stage) and indicated the potash feldspar i s i n the "microcline crypto-perthite" range of Tuttle (1952). These crystals appear to be p l a t e - l i k e i n the sye n i t i c rock and equant i n the quartz monzonite. The microcline microperthite forms large subhedral to euhedral grains i n nearly a l l the rocks. In the syenitic rocks some of i t forms the alternating zones of microperthite and plagioclase. Each zone i s p a r a l l e l to the others and p a r a l l e l to the c r y s t a l faces (see f i g . 9 ) . Many Uo. possible origins have been proposed f o r multiple zoning i n feldspars. These have been reviewed by Vance (1962) as follows: 1. Various mechanisms of repeated d i f f e r e n t i a l movement between feldspar crystals and l i q u i d (Bowen) 2. Pressure changes (e.g. H i l l s ) 3. Periodic v o l a t i l e release (Boone) l i . Diffusion i n the s o l i d state (Foster and Iharrola) 5. Unmixing (Turner and Verhoogen) 6. Diffusion-supersaturation (Harloff) D i f f e r e n t i a l movement, periodic pressure changes and periodic v o l a t i l e release do not seem applicable i n view of the i d e n t i c a l l y alternating zones of the microperthite and plagioclase of the c r y s t a l s . The changes would have to be uniform and regularly alternating. The o r i g i n of the textures by d i f f u s i o n i n the s o l i d state i s u n l i k e l y because of the highly preferred replacement necessary. Also, the problem i s not solved therefor t h i s does not explain the cuase of the preferred replace-ment. The high content of microcline i s the i n h i b i t i n g factor f o r an o r i g i n by unmixing of the microcline from the low a l b i t e form (the type now present i n the intrusion). High a l b i t e can contain s i g n i f i c a n t l y more although the low degree of metamorphism suggests a f a i r l y low temperature of i n t r u s i o n . The microperthite zones contain spindle shaped blebs of plagioclase and i t i s u n l i k e l y that a second type of unmixing would occur i n the same c r y s t a l exactly i n zones p a r a l l e l to the c r y s t a l form. The most reasonable merchanism i s the diffusion-supersaturation theory which needs alternating period of depletion and supersaturation of the two constituents. Feldspars with hourglass texture were found i n some of the rocks ( f i g . 15) Farquhar (I960) summarizes the following possible origins of hourglass texture: 1. Different c r y s t a l faces p r e c i p i t a t i n g d i f f e r e n t chemical substances. 2. Selective i o n i c adsorption. 3. Variations of the composition of the melt during growth. U. Impurities accreted as inclusions. 5. Differences i n molecular a t t r a c t i o n i n different directions of the c r y s t a l . 6. I n h i b i t i o n of tendency to twin. 7. Response of c r y s t a l to periodic stress. 8. Periodic resorption i n opposite sectors of the c r y s t a l . A l l the mechanisms seem applicable but the author favors the l a s t because i t can also account f o r more i r r e g u l a r shapes than the hourglass texture present i n the rocks of the complex. Vance (1962) favors i r r e g u l a r corrosion of pre-existing rims caused by pressure changes occurring as a magma ri s e s i n the crust as an or i g i n f o r patchy zoning i n plagioclase. Hourglass texture may be a s p e c i f i c type of patchy zoning and i t s texture may indicate a prefer-ence f o r resorption to occur i n a certain direction of the feldspar c r y s t a l l a t t i c e . The o r i g i n of e l l i p s o i d feldspar crystals ( f i g . lU) has been attributed by many petrologists to resorption (Tuttle and Bowen, 1958). These authors c i t e Sederholm as stating that high v i s c o s i t y , not resorption, has been the probably factor governing t h e i r o r i g i n on the basis of the lack of embayments. The author favors the resorption process f o r the micropethite e l l i p s o i d s , f o r the syenitic magma, with i t s w e l l oriented feldspar c r y s t a l s , probably had a low v i s c o s i t y and rounded embayments do e x i s t . ( i i i ) The f i n a l stage of feldspar c r y s t a l l i z a t i o n was that of mainly anhedral i n t e r s t i t i a l a l b i t i c grains which commonly occur as p a r t i a l rims about previous feldspar grains. U 2 . CHAPTER V CRYSTALLIZATION OF ROCK TYPES A. VARIATION DIAGRAM A variation diagram f o r these rocks ( f i g . 3k) was calculated from the average of the approximate modes (as i n table l ) of the rock types using i d e a l mineral compositions (from Winchell, 1951)• Fry.34 lUvic^.'aw d;^0y^ of +ke. 6 \ ; J w ^ t U l roc/<TflJ Cov^pU, Judged by th e i r a l k a l i - l i m e index, the rocks are close to the boundary between a l k a l i - c a l c i c and c a l i c a l k a l i series. The deviation from the i d e a l smooth curves i n variation diagrams can be attributed to addition to a system by assimilation (Barth, 1962, p.168) or subtraction during f r a c t i o n a l c r y s t a l -l i z a t i o n (Bowen, 1928, p .2U). The layered form of the shonkinite suggests i t was formed, i n part anyway, by c r y s t a l accumulation (explained under "Sequence of C r y s t a l l i z a t i o n of the Rock Types"). This evidence suggests to U3, the author that f r a c t i o n a l c r y s t a l l i z a t i o n i s at l e a s t p a r t i a l l y responsible f o r this deviation. Some assimilation has undoubtedly occurred which may also cause some deviation from smooth curves. The trends of the oxides are t y p i c a l f o r many c i t e d by Bowen (1928). The exception i s the Al^O^ l i n e whose anomalous form may be attributed, p a r t i a l l y at l e a s t to the f a c t that the weight compositions were calculated from the modes and not chemical analysis. In South Central B r i t i s h Columbia, there are various bodies of sye n i t i c rocks c a l l e d Coryell intrusions. The author plotted a variation diagram for these rocks but found no correlation between t h i s and the diagram for the Mount Fleet rocks. The Coryell diagram was constructed from various chemical analysis summarized by J.O. "Wheeler (19U9)» R SEQUENCE OF CRYSTALLIZATION OF THE ROCK TYPES The magma which formed the quartz monzonite was intruded and c h i l l e d along i t s contact with the r e l a t i v e l y cold Cache Creek rocks. The central area of th i s intrusion cooled more slowly and produced a coarse-grained porphyritic rocks. A p l i t i c d i o r i t e dykes which intrude both quartz monzonite phases were formed l a s t . The f i r s t magma which eventually formed the s y e n i t i c intrusions was c h i l l e d by the cooler Cache Creek rocks. The porphyritic quartz syenite i s t h i s c h i l l e d phase. The magma then cooled more slowly forming next the quartz syenite and then the syenite. The syenite i s the most abundant and variable i n composition. I t con-tains a l l gradations of mafic content. Syenite dykes intruded the early formed porphyritic quartz syenite during t h i s time. The shonkinite which i s the most inte r e s t i n g and unusual of the rocks, probably represents a d i f f e r -entiate of the syenite. I t i s considered to be a c r y s t a l accumulate, i n part at least, for the following reasons. ( i ) I t s layered form (s i m i l a r to "rhythmic layering" i n the well known basic complexes such as the S t i l l w a t e r ) . ( i i ) The occurrence of such a high proportion of euhedral garnet and aegirine-augite c r y s t a l s . ( i i i ) l t has the r a t i o of oxides of the syenite i f the oxides of the excess of garnet and aegirine-augite are subtracted from the shonkinite's calculated norm. ( i v ) The straight l i n e trends of the oxides i n the v a r i a t i o n diagram can be considered due to f r a c t i o n a l c r y s t a l l i z a t i o n which could produce such a rock; The shonkinite looks l i k e a skarn i n hand specimen. I t s occurrence d i r e c t l y on l i n e with the limestone layers (see f i g . $) would also suggest t h i s . The shonkinite, however, has i d e n t i c a l composition and textural features to that of the other syenitic rocks. The formation of the high proportion of garnet i n the shonkinite and sy e n i t i c rocks, whatever the origin of the mineral, decreased the amount of s i l i c a i n the magma so that nepheline syenite was probably formed. Most of the o r i g i n a l nepheline has been subsequently altered to n a t r o l i t e and can-c r i n i t e . Leucocratic monzonite dykes intruded the syenite a t t h i s time. U5. CHAPTER VI ORIGIN OF THE COMPLEX The complex (syeni t i c and quartz monzonite intrusions) i s considered, by the author, to be formed mainly by intrusion of a magma and not meta-somatism p r i n c i p a l l y on the following grounds: 1. As shown i n figure $, there i s no relationship of textures within the intrusions to those i n the Cache Creek rocks. 2. Lack of the high degree of regional metromorphism which commonly occurs i n areas where such metasomatized rocks are found. 3. D i l a t i o n offsets of syenite dykes ( f i g . 22). U. P a r t i a l truncation and disruption of f o l i a t i o n and bedding. The o r i g i n of a l k a l i c magma has been considered by many geologists. The main problem i s the low s i l i c a content of the body. Barth (1962) summar-izes the following p r i n c i p a l ways a l k a l i c rocks may be produced: 1. Simple f r a c t i o n a l c r y s t a l l i z a t i o n of primary basalt magma. 2. Gaseous transfer and thermo dif f u s i o n . 3. Assimilation of limestone. 1. Fractional C r y s t a l l i z a t i o n Bowen (1915) proposed that d i f f e r e n t i a t i o n of basa l t i c magma may, i n some circumstances produce a l a t e , low s i l i c a , high a l k a l i d i f f e r e n t i a t e . This he does by a breakdown of p o l y s i l i c a t e s to quartz and low s i l i c a l i q u i d . To produce an under-silicated magma requires the production and accumulation of leu c i t e and the l a t e r reaction of the magma with the c r y s t a l accumulate. At Mount Fleet the nepheline-potash feldspar intergrowths suggest an inversion from l e u c i t e . The closeness to a quartz r i c h intrusion which could be the quartz r i c h part, would also uphold Bowen1s theoretical views. The main objections to this theory i s the f a c t that the nepheline-feldspar intergrowths are anhedral i n form (not the shape of euhedral leucite). Shand (1952) does not believe such a s i l i c a deficient magma as Bowen suggests would survive intrusion through the quartz r i c h c r u s t a l rocks. U6. Holmes (1932) proposes the ori g i n of nepheline magma by removal of ol i v i n e and enstatite from peridotite magma. The objections to this theory are that no mafic inclusions or relations to ultrabasic bodies were found at Mount Fleet. 2. Gaseous Transfer and Thermo Diffusion Replacement by gaseous emanations or diffusion have been suggested as mechanisms for the production of syenites. The main d i f f i c u l t y i n connection with these processes i s the lack of a source of the a l k a l i c emanations and the general lack of explanation of the de s i l i c a t e d condition of these rocks (Shand, 1952). Smyth (1913) believes that slow c r y s t a l l i z a t i o n of a granitic magma produces an i n t e r s t i t i a l l i q u i d r i c h i n v o l a t i l e s and a l k a l i s which leave the magma. The main objections to such v o l a t i l e r i c h emanations forming the rocks at Mount Fleet i s the r e l a t i v e l y high percentage of ferromagnesium components and the s c a r c i t y of evidence of v o l a t i l e s (e.g. pegmatites,etc.). Boone (1962) believes of s i m i l a r rocks i n Northern Maine that potassium enrichment occurred by the upward transfer of potassium r i c h emanations and water. This evidently was i n response to variations i n pressure and tempera-ture during intrusion. There are not many hydrous minerals at Mount Fleet although water could have been l o s t without producing such minerals. There are no clear replacement textures, which Boone believes indica t i v e of this mechanism, involving potassium feldspar. G i l l s o n (1928) believes that the continuance of soda enrichment (as that i n magmas which produce a l b i t i z a t i o n ) of magmas, would lead to the formation of feldspathoids. I t i s true that t h i s method may use up a l l the free s i l i c a but i t does not explain well the occurrence of feldspathoids (Shand, 1952). Also, at Mount Fl e e t there i s much more potassium than sodium. Terzaghi (1935) believes hydrothermal a l t e r a t i o n and weathering may impori. amounts of potassium which may be added and soda and lime removed. Ii7. Potassium feldspars would be produced. At Mount Fleet there i s no obvious source of such potassium. 3. Assimilation of Limestone Daly's d e s i l i c a t i o n by assimilation of limestone theory requires the production of calcium s i l i c a t e s such as garnet and pyroxenes. (Bowen believes the plagioclase w i l l simply become more c a l c i c ) . These calcium s i l i c a t e s use up available s i l i c a and are removed from the melt y i e l d i n g an undersilicated magma. This assimilation requires much heat, as the s i l i c a t i o n of limestones i s an endothermic reaction (Shand, 1952). The oversaturated l i q u i d would apparently need a high temperature to carry i t over a high temperature "ridge" i n t o the nepheline f i e l d of Schairer and Bowen's nepheline-kiaphilite-quartz diagram. (See Schairer, 1950, p . 5 l U ) . The presence of CO2 and RvjO pressure may, however, s i g n i f i c a n t l y lower the temperature required. A low temperature would produce feldspar-rich rocks with possibly a l i t t l e nepheline. The occurrence of only a small amount of nepheline bearing rocks i n such complexes i s very common (Shand, 1952). The syenitic intrusions at Mount Fleet are i n contact with thick lime-stone beds. Andradite garnet, which i n Daly's hypothesis would be the main calcium s i l i c a t e produced, occurs i n varying but substantial amounts through-c, out the intrusion. I t has i t s highest concentration d i r e c t l y on s t r i k e with the large limestone layer which outcrops at Paul Lake. The reason this mineral was not more scattered i s probably that i t sank and accumulated near the place i t was produced ( p a r t i a l l y at least forming shonkinite). The o r i g i n of the abundant i r o n , to form the garnet, i n this area i s not known. Some probably o r i g i n a l magnetite was observed i n some limestone beds. The explanation of the low calcium content i n a rock that i s supposed to have assimilated large quantities of limestone i s d i f f i c u l t . This i s U8. shown by the low calcium content of the plagioclase (An^Q average). Perhaps the early production of calcium r i c h garnet and some calcium i n the pyroxene lower the calcium content of the magma e f f e c t i v e l y . Most of these minerals may have sunk out of sight but some concentrations, forming the shonkinite, are now exposed. In conclusion i t i s d i f f i c u l t to know i f Bower's views are true because this mechanism was presumably operative deep i n the crust. The gaseous trans-f e r and thermo diffusion processes f i n d no support at Mount Fleet. The author believes intruding granitic magma became de s i l i c a t e d by assimilation of lime-stone and i t s present position i n the crust on the following grounds: ( i ) The occurrence of much andradite (a skarn garnet) i n the intrusion. ( i i ) The lack of limestone inclusions i n the syenite although other Cache Creek rock inclusions do occur and limestone inclusions must have been o r i g i n a l l y present. ( i i i ) The occurrence of i d e n t i c a l garnets i n both the syenitic intrusions and a contact marble. ( i v ) The high concentration of andradite garnet d i r e c t l y on st r i k e with the large limestone layer. The common occurrence of a high potassium content i n these rocks can not be attributed to normal c r y s t a l l i z a t i o n (Barth, 1962). Some, not w e l l known process of concentration i s necessary. The author believes the high concentration of potassium can be attributed to the abundance of this element i n the o r i g i n a l magma. 1*9. CHAPTER VII RELATION OF THE SYENITE TO THE QUARTZ MONZONITE The many s i m i l a r i t i e s between the two rock types suggest that there i s some genetic r e l a t i o n between them. These two rock types are nearly i d e n t i c a l except f o r the greater quartz content of the quartz monzonite and the high garnet and pyroxene content i n the syenite. The process which removed the s i l i c a i s d i r e c t l y related to the possible o r i g i n of the garnet (whether the o r i g i n i s by c r y s t a l l i z a t i o n or formation i n a skarn). The formation of aegirine-augite apparently i n preference to plagio-clase may be due to the deficiency of quartz or alumina (Nockolds, 19U9). The reason the o r i g i n a l magma, which formed the syenite, did much assimilation while the quartz monzonite one did less i s possibly that the former was hotter or larger. I t i s also possible that the former encountered more limestone. Similar over-and-under-silicated rocks are described by Burnham (1959) at Crestmore. There, a quartz d i o r i t e intruded magnesian marbles to form an i r r e g u l a r l y shaped contaminated border zone which was made up of d i o r i t i c (including gabbroic) and s y e n i t i c rocks. Aegirine-augite r i c h d i o r i t i c rocks were considered to have formed by early c r y s t a l l i z a t i o n while the syenitic rocks (which contain some garnet) were the products of c r y s t a l l i z a t i o n of a residual magma. The rocks at Mount Fleet show par a l l e l i s m to these rocks at Crestmore f o r the syenitic rocks, are believed to be simply the more contam-inated equivalents of the nearby quartz monzonite ones. At Crestmore a general decrease of s i l i c a was p a r a l l e l e d by an increase of aegirine-augite (an increase of CaO, MgO, FeO, Fe2<>3 a n d T i 0 2 ^ which appears generally also to p a r a l l e l the v a r i a t i o n at Mount Fleet (see va r i a t i o n diagram). 50. CHAPTER VIII CONCLUSIONS A granitic magma intruded the limestones of the Cache Creek rocks and was d e s i l i c a t e d by the formation of calcium s i l i c a t e s . A quartz monzonite was intruded, with apparently l i t t l e assimilation near the s i t e of the syenitic intrusions. The r e l a t i v e age of the syenitic and quartz monzonite intrusions i s unknown. They appear to the author to be genetically related because of t h e i r many s i m i l a r i t i e s . The reason the magma which produced the syenitic intrusions assimilated more limestone than that of the quartz monzonite intrusions i s not w e l l known. The production and s e t t l i n g of the garnet and aegirine-augite caused a decrease of s i l i c a i n the magma. This residual magma produced rocks low i n s i l i c a . This magma produced a quartz syenite at the contacts with the Cache Creek rocks, a syenite with a shonkinite d i f f e r e n t i a t e and a nepheline syenite at the middle of the pluton. There were various dyke rocks related to each of these d i f f e r e n t i a t e s . Porphyritic quartz syenite dykes are related to the quartz syenite; syenite dykes to the syenite; and leuco monzonite and d i o r i t e are related to the nephelene syenite. The complex i s si m i l a r to ones containing more c a l c i c plagioclase (An3o) described by many authors. The lack of c a l c i c plagioclase i s attributed to the early formation and s e t t l i n g of andradite garnet and to a minor extent aegirine-augite. These ea r l y produced minerals formed accumulates. The reason the garnet and aegirine-augite assembage was formed instead of the usual b i o t i t e and hornblende i s possibly due to the lack of water i n the magma. The effect of a high concentration of lime may also be the factor. The odd "patchy" zoning i n feldspar probably represents pressure changes during intrusion. These minerals also have odd o s c i l l a t o r y zoning believed to have formed by the mechanism shown by the diffusion-supersaturation theory of Si. Harloff. The syenitic rocks show a clear concentric arrangement of aligned feldspar laths. This feature may be due to intrusion of a c r y s t a l r i c h magma. The quartz monzonite has equant feldspar grains and, therefore, no pattern was observed. 52. Barth, T. F. W.,1962 Boone, G. M.,1962 Bowen, N. L., 1915 Buckley, H. E . , 1 9 5 l Buddington, A. F.,1939 Burnham, C. W.,1959 Campbell, C. D.,1939 Cockfield, W. E.,19U8 Daly, R. A.,1910 Dawson, I89I4. Farquhar, 0. C.,1960 G i l l s on, J. I . , 192U Holmes, A.,1931 Johannsen, A.,1939 Krauskopf, K. B . , 19Ul Nockolds, S. R.,19U9 Schairer, J. P.,1950 SELECTED BIBLIOGRAPHY "Theoretical Petrology", J. Wiley & Sons. Potassic Feldspar Enrichment i n Magma: Origin of Syenite i n Deboullie D i s t r i c t , Northern Maine. Geol. Soc. Am. Vol. 73, p . l U 5 l - l U 7 6 . The Late Stages of the Evolution of the Igneous Rocks. Jour. Geol. Vol. 23. 1928 "The Evolution of the Igneous Rocks, Princeton Press. "Crystal Growth", J. Wiley & Sons. Adirondack igneous rocks and t h e i r metamorphism. Geog. Soc. Am. Mem. 35Up. Contact Metamorphism of Magnesian Limestones at Crestmore, C a l i f o r n i a , G. S. A. B u l l . Vol. 70, p.879-920. The Kruger Alkaline Syenites of Southern B r i t i s h Columbia. Am. Jour. Sc. Vol. 237, pp.527-5U9-Geology and Mineral Deposites of Nicola Map-Area, B r i t i s h Columbia. Geol. Surv. Canada, mem. 2U9. The Origin of the Alkaline Rocks: B u l l . Geol. Soc. Amer., Col. 21, pp. 87-118. Geol. Surv. Canada, mem. 68 Occurrences and o r i g i n of the hourglass structure, Report of the 21st Session Norden Part XXI, PP.19U-200. On the Origin of the Alkaline Rocks, Jour. Geo. Vol. 36, pp.U71-U7U. The Problem of the Association of Acid and Basic Rocks i n Central Complexes. Geol. Mag. Vol. 68, pp.2lO.-255. "A Descriptive Petrography of the Igneous Rocks" Vol. 1, Univ. of Toronto Press. Intrusive Rocks of the Okanagan V a l l e y and the Problem of th e i r correlation, Jour. Geol. Vol.XLIV, pp.1-53. On the occurrence of neptunite and eudialyte i n quartz bearing syenite from Bornavave, Carlingford, Ireland, Min. Mag., Vol. 29, pp.27-33. The a l k a l i feldspar j o i n the system NaAnSiO^-KAlSiOi^-SiO^, Jour. Geol. Vol. 58. 53. Shand, S. J . ,1952 Skinner, B. J . ,1956 Smyth, C. H., Jr.,1913 Terzagki, R. D. Tuttle, 0. F.,1952 Tuttle, 0. F.,and Bowen, N. L.,1958 Uglow, W. L . ,1921 Vance, J. A.,1962 Wheeler, J. 0.,19U9 Winchell, A. N.,and Winchell, H . , 195l Winchell, H.,1958 Wright, W. I., 1938 The Present Status of Daly's Hypothesis of The Alkaline Rocks. Am. Jour. Sc. Vol. 2U3-A, pp.U85-507. Physical properties of end members of the garnet group, Am. Min. I4I, 1956. The Chemical Composition of the Alkaline Rocks, and I t s Significance as to t h e i r Origin: This Journal, Ser. ak, Vol. 36, pp.33-U6. The o r i g i n of the Potash-Rich Rocks, Am. Jour. Sc. 5th Sess., Vol. 24, p.38O. Optical studies on a l k a l i feldspars Am. Jour. Sc. Bowen Vol., pp.553-567. Origin of Granite i n the l i g h t of experimental studies i n the system NaAlSi^O^-KAlSi^Og-S^-^O, Geol. Am. S o c , mem. 7U. Geology of the North Thompson Map area-Geol. Surv. Canada, Sum. Rept. pt. A, pp.76-78. Zoning i n igneous plagioclase: Normal and Os c i l l a t o r y Zoning, Am. Jour. Sc., Vol. 260, pp.7U6-760. "An examination of the Analyses of Igneous Rocks of B. C." Unpublished Masters Thesis, University of B r i t i s h Columbia. "Elements of Optical Minerology", Part I I , J. Wiley & Sons. The Composition and Physical Properties of Garnet Am. Min. h3, pp.595-600. The composition and occurrences of garnets. Am. Mon. 23, pp.936-UU5« 

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