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The geology of Kinskuch Lake area, British Columbia Gale, Robert Earle 1957

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THE GEOLOGY OF KINSKUCH LAKE AREA, BRITISH COLUMBIA BY ROBERT EARLE GALE B.Sc. (Honors) University of Alberta, 1955 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 this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1957 i ABSTRACT Kinskuch Lake area covers a fifty-square mile portion of the Portland Canal d i s t r i c t of western B r i t i s h Columbia. Kinskuch Lake l i e s near the eastern border of the Coast Mountains, approximately twelve miles north of the port of A l i c e Arm. Reconnaissance mapping of the area on a scale of 1" = 1000 1 was done during part of the summer of 1956. Rock specimens collected i n the f i e l d were examined microscopically and the results of the l a t t e r i n v e s t i g a t i o n form the greater part of thi s t h e s i s . The interbedded volcanic and sedimentary rocks of Kinskuch Lake area were deposited during the period of Mesozoic volcanism and sedimentation which was widespread throughout western B r i t i s h Columbia and southeastern Alaska. Near Kinskuch Lake, the e a r l i e s t products of Mesozoic v o l -canism are represented by augite porphyry volcanic breccias, c r y s t a l tuffs, flows and flow breccias outcropping along the western margin of the map area. Augitic volcanics are over-l a i n to the east by in t e r f i n g e r i n g f e l s i t i c breccias and t u f f s , sedimentary rocks and greenstone. East of Kinskuch Lake, the l a t t e r rocks pass gradationally into a thick over-l y i n g sequence of f e l s i t i c volcanic breccia, c r y s t a l t u f f s and feldspar porphyry flows. The youngest rocks outcrop near the eastern margin of the map area. Here, a r g l l l i t e s and conglomerates o v e r l i e f e l s i t l c volcanic breccia and interbedded t u f f . The Mesozoic volcanic and sedimentary rocks were folded, faulted and intruded by keratophyric and lampro-phyric dykes. As a l a s t stage i n the geological sequence of events, volcanic rocks at the southeast corner of Kinskuch Lake were altered and mineralized. Highly fractured or sheared greenstone and f e l s i t i c volcanics were altered to c h l o r i t e , p y r i t e , epidote, s e r i c i t e quartz and c a l c i t e . Minor chalcopyrite mineralization accompanied rock a l t e r a t i o n and many small quartz-carbonate veins cut the altered rocks. Some of the l a t t e r veins carry p y r i t e , chalcopyrite and traces of sphalerite and galena. A l b i t i z a t i o n of some of the igneous rocks outside the altered zone accompanied the widespread carbonate a l t e r a t i o n . In presenting t h i s thesis i n p a r t i a l fulfilment of the requirements f o r an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the Head of my Department or by his representative. It i s understood that copying or publication of t h i s thesis f o r f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of- Geology and Geography The University of B r i t i s h Columbia, Vancouver 8, Canada. Date A p r i l 2h* 1957  i i i ACKNOWLEDGMENT The writer i s deeply indebted to Messrs. J.S. Scott and C.S.Ney, of Northwestern Explorations Ltd., for the data, f i n a n c i a l assistance and suggestions which they supplied. Dr. K.C.McTaggart, Dr. V/.H. White and Dr. J.V. Ross contributed h e l p f u l discussion and advice to the writer for which he i s also g r a t e f u l . Mr. W.R.Danner kindly i d e n t i f i e d f o s s i l s . Thanks are due to Mr. J.A.Donnan for the many thin-sections which he ably prepared. Chemical analyses were carried out under the supervision of Mr. G.S.Eldridge. TABLE OF CONTENTS Page CHAPTER I Introduction 1 Scope of Investigation 1 Location of Map Area 2 Access 2 Physiography .. 4 CHAPTER II Geology of A l i c e Arm D i s t r i c t 8 Previous Work 8 General Geology 8 CHAPTER III Geology of Kinskuch Lake Area 10 Introduction 10 Table of Units 11 Sedimentary Rocks . . . 13 D i s t r i b u t i o n 13 Petrography 13 A r g i l l i t e . 1 3 Calcareous Augite Tuff 14 Volcanic Rocks 14 Augite Porphyry 14 Di s t r i b u t i o n 15 Petrography 15 Page Augite porphyry flows 15 Augite porphyry flow breccias . . . . 18 Augite porphyry pyroclastics . . . . 20 Altered augite porphyry flows . . . . 21 F e l s i t i c Rocks 21 D i s t r i b u t i o n 22 Petrography 22 F e l s i t i c volcanic breccia 22 Coarse-bedded f e l s i t i c t u f f . . . . 27 Thin-bedded f e l s i t i c t u f f 28 Purple to Green f e l s i t i c t u f f . . . 29 Feldspar porphyry flows 30 Reddish Color i n F e l s i t i c Rocks 35 A l b i t i z e d Andesite-Greenstone 36 D i s t r i b u t i o n 37 Petrography 37 Age 38 Correlation 39 Intrusive Rocks 40 Hornblende Keratophyre 41 Keratophyre, Quartz Keratophyre 44 Quartz Feldspar Porphyry 45 Augite Quartz D i o r i t e 45 Lamprophyre 47 Discussion of A l b i t i z a t i o n 50 Conclusions 50 Source of A l b i t i z i n g Media 52 S t r u c t u r a l Geology 54 Folding ' 54 Faulting 55 CHAPTER IV" Economic Geology 57 Introduction 57 Mineralization 58 Disseminated 58 Vein 59 A l t e r a t i o n 60 Genesis of Mineralization and A l t e r a t i o n . . . . 62 Conclusion 63 Bibliography 64 ILLUSTRATIONS Figure Page I. Map of Portland Canal Area, Kinskuch Lake Area Inset 3 I I . East-west Cross Section of Map area . . . . i n p o c k e t l ^ ^ / I I I . Stereographic Plot of Poles to } 150 Veins i n pocket m T IV. Stereographic Plot of Poles to \ • 300 Shears i n pocket Plates I. Mount Lavender and the southern end of Kinskuch Lake from the west 6 II . Photomicrograph of amygdule of sodic feldspar 17 I I I . Augite porphyry flow breccia 19 IV. Photomicrograph i n ordinary l i g h t of matrix of flow breccia 19 V. Augite porphyry pyroclastics 20 VI. Red F e l s i t i c breccia 23 VII. Photomicrograph of a veinlet of c a l c i t e and sodic feldspar 24 VIII. Photomicrograph of v e i n l e t of c a l c i t e and fresh sodic feldspar bordering s e r i c i t i z e d plagioclase 24 IX. Hornblende r i c h f e l s i t i c breccia 26 X. Coarse-bedded f e l s i t i c t u f f 27 XI. Red, thin-bedded t u f f 28 XII. Coarse feldspar porphyry flow 32 Plates Page XIII. Photomicrograph of phenocryst i n coarse feldspar porphyry . . . 32 XIV. Photomicrograph of patches of plagio-clase i n potash feldspar phenocryst . . . . 33 XV. Red-rimmed fragments i n f e l s i t i c breccia 3 5 XVI. Red band i n f e l s i t i c breccia 36 XVII. Flow structure i n greenstone 38 XVIII. Hornblende keratophyre feeder viewed from the west 42 XIX. Photomicrograph of hornblende keratophyre 43 XX. Veinlet of quartz, c a l c i t e and sodic feldspar cutting s e r i c i t i z e d plagio-clase c r y s t a l 47 XXI. White segregation band i n lamprophyre . . . . 49 TABLES Page I. Summer Temperatures 6 II. Chemical analysis and calculated normative minerals of an augite porphyry flow 17 I I I . Chemical analysis and calculated normative minerals of reddish f e l s i t i c breccia 25 IV. Chemical analysis and calculated normative minerals of massive f e l s i t i c t u f f 30 V. Chemical analysis and calculated normative minerals of coarse feldspar porphyry flow 34 MAP Geological Map of Kinskuch Lake Area Scale 1" - 1000' Contour Interval 500' THE GEOLOGY OF KINSKUCH LAKE AREA, BRITISH COLUMBIA CHAPTER I INTRODUCTION Scope of Investigation The material used i n writing t h i s thesis was colle c t e d during part of the summer of 1956, i n the course of employment with Northwestern Explorations Limited. The main object of the summer's work was the investigation of the altered and mineralized rocks near Kinskuch Lake, B r i t i s h Columbia. Evaluation of the mineral deposit was carried out by diamond d r i l l i n g and detailed mapping at scales of 1" = 40' and 1" = 400'. Along with the detailed work i n the altered-mineralized zone, reconnaissance mapping of the rocks i n the area surrounding the lake was done by means of pace and compass traverses. Data obtained by traverses was plotted on a contoured base map drawn at a scale of 1" = 1000'. 2 The geological map of Kinskuch Lake Area, which is the result of the reconnaissance exploration described above, forms the nucleus of the present work. This thesis deals with a l l phases of the general geology of the map area. Location of Map Area Kinskuch Lake region, as defined i n this t h e s i s , i s a fifty-square-mile area near the eastern side of the Coast Mountains, i n the Portland Canal d i s t r i c t of B r i t i s h Columbia (Figure I ) . The lake i s approximately twelve miles north of the port of A l i c e Arm. A l i c e Arm i t s e l f i s about eighty a i r miles north of the c i t y of Prince Rupert. Other well known points near A l i c e Arm are Anyox, twelve miles west, Stewart, forty miles northwest and Torbrib S i l v e r mine, f i f t e e n miles north up the K i t s a u l t River. Access During the late summer months, Kinskuch Lake i s conveniently reached by means of a float-equipped plane from Prince Rupert, Terrace or A l i c e Arm. The l a t t e r port i s regularly serviced by P a c i f i c Western A i r l i n e s from Prince Rupert. An alternative means of reaching the area i s to drive from A l i c e Arm up the K i t s a u l t v a l l e y to Torbri't Mine FIGURE I PORTLAND CANAL AND ADJACENT AREAS KINSKUCH LAKE AREA-INSET 4 and thence to walk the remaining s i x miles east over a good t r a i l to Kinskuch Lake. Phys iography Drainage and Vegetation: Kinskuch Lake is near the eastern border of the Coast mountains, at an elevation of 3 7 5 0 feet. The lake, about one and one half miles wide east to west and some four miles long north to south, l i e s i n a height of land between the K i t s a u l t River v a l l e y to the west and Nass River v a l l e y to the east. The steep, narrow canyon of the Kinskuch River runs east from the north end of the lake to the Nass whereas most streams i n the h i l l s to the west of the lake drain west to the K i t s a u l t River. At the south east corner of the lake a g l a c i e r about 1000 feet wide continually discharges ice into the lake during the summer months. Since 1 9 3 9 the ice front has retreated about 1000 feet (60 feet per year). Other ex-tensive snowfields surrounding the lake contribute great quantities of water to i t . The h i l l s round about the lake are p r a c t i c a l l y bare of trees except for rather scrubby pine and hemlock growing at a few places. The only other vegetation i s moss heather and wild flowers. 5 Summer Climate: Spring and summer of 1956 were sunnier than normal except for periods i n June and August. In May and June the weather was dominantly clear with a few snow f l u r r i e s . Ice on the lake was broken near shore by June 26 th , but the main mass was s t i l l i n t a c t . In July weather was f a i r to sunny and the lake was e s s e n t i a l l y clear of ice on July 9 t h . About two weeks were f a i r and clear i n August and two were cloudy with almost continual r a i n and some fog. Snow f e l l above the 6500 foot l e v e l on August 28th. In September, colder weather began to s e t t l e i n but a two foot f a l l of snow on September 18th, quickly melted away at lake l e v e l . At this time snow began to accumulate continuously above 4500 feet. TABLE I SUMMER TEMPERATURES Month High F° Low F° Mean F° May 73 25 46 June 72 23 44 July 78 32 52 August 76 34 50 September 67 22 43 6 Topography: PLATE I Mt. Lavender and s o u t h end o f K i n s k u c h Lake viewed from the west H i l l s i m m e d i a t e l y t o t h e n o r t h and s o u t h , and e s p e c i a l l y west of the l a k e b a s i n , a r e c o m p a r a t i v e l y rounded and low. J u s t t o the e a s t of the b a s i n , Mount Lavender a t an e l e v a t i o n o f 7660 f e e t towers n e a r l y 4000 f e e t above l a k e l e v e l . F u r t h e r east f o r some two m i l e s , t h e topography con-t i n u e s t o show r a t h e r h i g h jagged r i d g e s r u n n i n g n o r t h t o s o u t h . V a l l e y s between t h e s e r i d g e s a r e f i l l e d by i c e and snow and g l a c i a l tongues f l o w n o r t h and s o u t h from t h e s e i c e masses. Beyond the e a s t e r n edge of the map a r e a , the jagged r e l i e f g i v e s way t o the r a t h e r wide f l a t v a l l e y of the Nass R i v e r . The form of t h e s e t o p o g r a p h i c f e a t u r e s i s i n p a r t 7 brought about by the d i f f e r i n g l i t h o l o g y of the rocks to the east and west of the lake. Sedimentary rocks to the west of Kinskuch Lake are probably more e a s i l y eroded than the massive volcanic breccias and t u f f s to the east. The extent of g l a c i a t i o n was probably another factor i n the determination of the present r e l i e f as i t appears that ice masses once completely covered the rocks to the north, west and south of the lake but did not erode the higher ridges to the east of i t . 8 CHAPTER II GEOLOGY OF ALICE ARM DISTRICT Previous Work Hanson (1935) described the whole of Portland Canal area from a point north of Stewart south to A l i c e Arm. His memoir i s the only published report describing the rocks near Kinskuch Lake. Black (1951) did detailed work i n the upper portion of the K i t s a u l t v a l l e y , to the west of Kinskuch Lake. General Geology A l i c e Arm d i s t r i c t l i e s along the eastern margin of the northern Coast intrusions. At a point about four miles west of the port of A l i c e Arm, the contact between Coast intrusions and older rocks strikes northwest through the centre of the d i s t r i c t . T e r t i a r y b a s a l t i c lavas cap Table Mountain south of A l i c e Arm. The older i n t r u s i v e , volcanic and sedimentary rocks have been assigned by Hanson to the Hazelton Group. Igneous members of this group occur as three large bodies separated and surrounded by conformable sedimentary rocks. The Theophilus body, about s i x miles wide and the K i t s a u l t body, 9 two miles across, both l i e east of K i t s a u l t River. Klayduc body, which is up to two miles wide, l i e s to the west of the K i t s a u l t v a l l e y . A l l three bodies s t r i k e north and have been traced i n this d i r e c t i o n up to sixteen miles from t h e i r southern termination at A l i c e Arm. Within the Hazelton group Hanson included a r g i l l i t e , quartzite, greywacke, limestone, t u f f aceous sediment, breccia, t u f f , augite porphyrite, f e l s i t e , amphibolite and gabbro. He found the most common sedimentary rock to be black a r g i l l i t e . By addition of coarser grains the l a t t e r rock was seen to grade into quartzite and greywacke. Pebbles of s l a t e and chert were found to be common i n conglomerates and the l a t t e r rocks by admixture of pyroc l a s t i c material graded into volcanic breccias. Regarding the igneous rocks, Hanson states: There are only two main types, feldspar porphyry ( f e l s i t e s ) and augite porphyrite, and the corr-esponding fragmental types. (1935) (p. 21). By microscopic investigation, Hanson found that feldspar porphyry contained orthoclase and plagioclase ranging i n composition from a l b i t e to oligoclase. Other minerals i d e n t i f i e d were b i o t i t e , apatite, s e r i c i t e , c a l c i t e and c h l o r i t e . Thin-sections of augite porphyrite were seen to contain rather fresh augite phenocrysts and highly altered cr y s t a l s of orthoclase and acid plagioclase. The groundmass i n many specimens of augite porphyrite consisted mainly of c h l o r i t e , s e r i c i t e and c a l c i t e . 10 CHAPTER III GEOLOGY OF KINSKUCH LAKE AREA Introduction The oldest volcanic rocks near Kinskuch Lake are augite porphyry flows, flow breccias and pyroclastics out-cropping along the western side of the map area. These igneous rocks are underlain by sedimentary rocks and overlain i n the south portion of the map area, by f e l s i t i c fragmental volcanics. In northern l o c a l i t i e s , augite porphyry rocks are overlain by a series of alternating and in t e r f i n g e r i n g f e l s i t i c breccias and t u f f s , sedimentary rocks and green-stone. Intercalated volcanic and sedimentary beds grade eastward into overlying massive f e l s i t i c breccia and a thick f e l s i t i c tuff-flow sequence. The youngest rocks are a thick series of sedimentary beds overlying f e l s i t i c pyroclastics at the eastern edge of the map area. After a period of folding and f a u l t i n g , sedimentary and volcanic rocks were intruded by dykes and small stocks. Intrusive rocks include v a r i e t i e s i d e n t i f e d as hornblende keratophyre, keratophyre and quartz keratophyre, quartz feldspar porphyry, augite quartz d i o r i t e and lamprophyre. Late i n the geological sequence of events, green-11 stone and f e l s i t i c fragmental volcanic rocks near the south-east corner of Kinskuch Lake were altered and mineralized. The rocks of the altered zone are composed of v a r i a b l e amounts of p y r i t e , c h l o r i t e , epidote, chalcopyrite, s e r i c i t e , quartz and c a l c i t e . Quartz-carbonate sulphide veins cut the altered rocks. Carbonate a l t e r a t i o n i s widespread through-out igneous and sedimentary rocks. In some Igneous rocks, the formation of c a l c i t e was apparently accompanied by a l b i t i z a t i o n of plagioclase. Table of Units Because of the variable Interfingering nature of the sedimentary and volcanic rocks and l a t e r deformation of these beds, the true thickness of any sequence i s l a r g e l y a matter of estimation. The thicknesses l i s t e d below should be considered i n this l i g h t . The rock sequence shown is true only of portions of the map area. No attempt has been made to d i f f e r e n t i a t e between successive bands of sedimentary rock and t h e i r relationships to each other are not f u l l y understood. 12 TABLE OF UNITS Name Character Thickness Intrus ive Rocks Lamprophyre Augite Quartz D i o r i t e Quartz Feldspar porphyry Keratophyre, Quartz Keratophyre Hornblende Keratophyre A r g i l l i t e Not mapped F e l s i t i c Breccia Mainly Coarse Volcanic Breccia with some bedded t u f f Mas s iv e F e l s i t i c t u f f Green to purple massive c r y s t a l t u f f Feldspar porphyry flow 6000 feet Thin-bedded f e l s i t i c t u f f Reddish c r y s t a l t u f f Coarse-bedded f e l s i t i c t u f f Green to purple c r y s t a l t u f f F e l s i t i c Breccia Green to red coarse volcanic breccia 4000 feet Sedimentary rock A r g i l l i t e , impure lime-stone, conglomerate 5000 feet A l b i t i z e d Andesite (Greenstone) Massive green c r y s t a l t u f f and some flows F e l s i t i c Breccia Coarse volcanic breccia with some interbedded t u f f 5000 feet Sedimentary rock A r g i l l i t e , Conglomerate and Calcareous Augitic t u f f F e l s i t i c Breccia Coarse volcanic breccia and interbedded t u f f Augite Porphyry rocks Flows, Volcanic breccia and c r y s t a l t u f f , flow breccia 2000 feet. A r g i l l i t e not mapped Sedimentary Rocks The major part of the sedimentary rocks i s of thin-bedded a r g i l l i t e with subordinate argillaceous t u f f , calcareous augi t i c t u f f , cherty or calcareous conglomerate and fine-grained, impure, white limestone. D i s t r i b u t i o n : The sedimentary rocks at the western edge of the map area are apparently the oldest rocks i n the v i c i n i t y of Kinskuch Lake. Other sedimentary rocks which are probably younger than those to the west, ov e r l i e augite porphyry volcanics and l o c a l l y i n t e r f i n g e r with f e l s i t i c pyroclastics and greenstone to the west, north and east of the lake. At the eastern edge of the map area, a thick series of sedim-entary rocks, which are continuous with those forming the Nass v a l l e y , o v e r l i e f e l s i t i c breccia and t u f f s . Petrography:". A r g i l l i t e : In a t y p i c a l handspecimen of a r g i l l i t e , fine-grained black bands alternate sharply with bands of r e l a t i v e l y coarse grey grains. These layers are up to one-h a l f inch thick and cross bedded. Unfortunately, the l a t t e r feature i s not well developed and top determinations are d i f f i c u l t where grain gradation is not notable. Microscopically, i t i s seen that grains forming one of the coarser portions of an a r g i l l i t e measure about .1 mm. across and are not well rounded. Quartz grains make up 15%, carbonate, some of which i s secondary, makes up about 35% and the remainder of the rock i s plagioclase of intermediate composition and potash feldspar. Calcareous Augitic Tuff: Thin beds of calcareous a u g i t i c t u f f occur i n a r g i l l i t e sequences and are therefore included here as a sedimentary rock. This t u f f i s much coarser-grained than a r g i l l i t e s and has a w e l l defined s t r a t i f i c a t i o n , e a s i l y seen owing to an alternation of softer and more resistant bands about one-half inch thick. In thin-section, the average grain s i z e i s seen to be about .5 mm. Resistant bands are composed of about 60% feldspar and f e l s i t i c rock fragments and 40% fresh augite. Softer bands are formed by 60% c a l c i t e , 20% augite and 10$ feldspar. Volcanic Rocks Augite Porphyry Augite porphyry rocks are the flows, p y r o c l a s t i c breccias, c r y s t a l t u f f s and flow breccias which i n hand specimen show dark green crystals or c r y s t a l fragments of fresh augite, as a prominent constituent. The most abundant representatives of these aug i t i c rocks are flows and flow breccias. The thickness and extent of i n d i v i d u a l flows are unknown since no contacts were seen. Locally, the extrusives give way to s t r a t i f i e d pyroclastics but work was not s u f f i c -i e n t l y detailed to determine the i n t e r - r e l a t i o n s h i p s between the two d i f f e r e n t types of volcanic rocks. At one place i n the main zone of a u g i t i c rocks, a s i l l - l i k e body of augite porphyry outcrops. This body may be an intrusive equivalent of augite porphyry volcanics. D i s t r i b u t i o n : The occurrence of augite porphyry rocks i s mainly r e s t r i c t e d to a zone near the western edge of the map area. Here, a u g i t i c volcanics outcrop between underlying a r g i l l i t e and overlying f e l s i t i c breccias or sedimentary rocks. Some thin a u g i t i c flows are interbedded with f e l s i t i c breccias, west of the south end of Kinskuch Lake. Two other i s o l a t e d patches of augite porphyry volcanics outcrop west of the north end of the lake and appear to o v e r l i e f e l s i t i c breccia and sedimentary rocks, at this point. Petrography: Augite Porphyry Flows: In a handspecimen of augite porphyry flow rock, ; augite crystals generally measure from one-sixteenth to one-half inch across. The matrix surrounding augite is fine-grained and green, weathering d u l l green or white. In most specimens the matrix encloses white amygdules of c a l c i t e and other minerals. In thin-sections of flows, m i c r o l i t e s of plagio-clase, fine flakes of chlorite and much brown crypto-crystalline material, possibly originally glassy, form a pilotaxitic to felted groundmass surrounding phenocrysts of plagioclase and pyroxene. In some specimens, pyrrhotite and hematite are also present as groundmass constituents. Round amygdules and connecting veinlets f i l led with chlorite, sodic feldspar calcite and quartz are dispersed through the flow matrix. (Plate II). Feldspar phenocrysts are highly altered with the development of sericite and calcite. In other flows the plagioclase is relatively fresh. Twinning of these feldspars is sharp and extinction angles of up to 12° X C and negative relief indicate a composition near An-j_Q. The zoned pyroxene is an aegirine-augite, pale green in color and somewhat pleochroic. The optic sign is positive and 2V is about 60° . Extinction angles XAC range up to about 40° . The refractive index nB determined with oils , is between 1.683 and 1.692. Augite forms 30% of the rock, plagioclase, in matrix and phenocrysts $0% and chlorite, etc. 20%, PLATE II .5 m.m. i i Photomicrograph of amygdule of sodic feldspar A p a r t i a l analysis of a t y p i c a l specimen of an amygdaloidal augite porphyry flow, and a l i s t of the c a l -culated normative minerals and their percentages is given below. In c a l c u l a t i o n of a l l norms i t was assumed that the weight percentage of F e 2 0 2 determined i n the chemical analy-si s was d i v i s i b l e into FeO and F e 2 0 ^ i n a r a t i o of 3 : 1 TABLE II Oxide Weight Percentage Normative Min-erals and per-centage S i 0 2 51.20 orthoclase 7.0 Al203+Ti0 2 16.60 a l b i t e 27.5 F e 2 0 3 2.62 anorthite 26.5 Fe6 7.75 diopside 25.5 MgO 6.40 hypersthene 2.0 CaO 10.80 o l i v i n e 9.5 Na 20 3.30 magnetite 3.5 K 20 1.18 99.85 101 .5 18 ...Although staining indicated the presence of a f a i r proportion of potash i n augite porphyry rocks, the percentage of normative orthoclase i s very low. Most of the substance which stained must be present i n the cryptocry-s t a l l i n e material of the flow matrix. The normative per-centages of plagioclase and pyroxene agree with the amounts of these minerals which were noted i n thin-sections. The normative composition of plagioclase i s A n ^ , assuming a l l the CaO calculated as normative anorthite is contained i n plagioclase i n the rock. Augite Porphyry Flow Breccia: Megascopically, the flow portion of augite porphyry flow breccia i s e n t i r e l y s i m i l a r to the augi t i c flows, just described. White frag-ments of c r y s t a l l i n e a u g i t i c rock"are surrounded by the flow matrix. These fragments are quite rounded and measure from one inch up to about s i x inches across. Under the microscope i t i s seen that the flow portion of these flow breccias has a f e l t e d groundmass formed of microclites of plagioclase, fine flakes of c h l o r i t e and much brown cr y p t o c r y s t a l l i n e material. This groundmass is crowded with innumerable, round blebs which are possibly sodic feldspar. (Plate IV). A few amygdules of sodic f e l d -spar and c h l o r i t e are present i n the matrix. Zoned augite and a few s e r i c i t i z e d plagioclase crystals comprise the phenocrysts i n the flow portion of this rock. PLATE III Augite porphyry flow breccia PLATE IV • i Photomicrograph, i n ordinary l i g h t of matrix of flow breccia 20 Along the contacts with rock fragments are vein-le t s and connecting amydul.es of c h l o r i t e , quartz and plagio-clase. The breccia fragments are porphyritic having pheno-crysts of indeterminable s e r i c i t i z e d plagioclase and zoned augite enclosed i n a groundmass of fine c h l o r i t i c p a r t i c l e s and dark cr y p t o c r y s t a l l i n e substance. Vesicles contain c h l o r i t e , sodic feldspar and some epidote. Augite Porphyry Pyrocl a s t i c s : Interbedded augite porphyry volcanic breccias and c r y s t a l t u f f s are green on fresh surfaces and white or brown, where weathered. The matrix of the volcanic breccias is s i m i l a r to the interbedded t u f f s . C r y s t a l l i n e a u g i t i c rock fragments i n these breccias measure up to a foot across. PLATE V Augite porphyry pyroclastics 21 In thin-sections of t u f f i t i s seen that augite occurs as c r y s t a l s , more or less broken, about .6 mm. wide and 1.2 mm. long. Augite composes 40$ of the rock and the remaining 60% i s a mixture of highly altered plagioclase fragments, f i n e flakes of c h l o r i t e and p a r t i c l e s of altered c r y p t o c r y s t a l l i n e material. Altered Augite Porphyry Flows: In at least two places where augitic flows and f e l s i t i c t u f f s and breccias are i n contact, the contact i s marked over a width of about 15 feet by a l t e r a t i o n that i s r e s t r i c t e d to the porphyry flows. In the altered rock, augite is replaced by a grey-i s h mixture of carbonate and c h l o r i t e and zoning of these crystals is made apparent. In thin-section i t i s seen that feldspars are re-placed by s e r i c i t e and carbonate and the groundmass by c h l o r i t e . F e l s i t i c Rocks: The term " f e l s i t i c rocks" i s applied, following Hanson's usage, to a l l the t u f f s , volcanic breccias and flows which i n hand specimen appear to contain few or no mafic minerals. In some f e l s i t i c rocks a good deal of f e l d -spar is v i s i b l e . Colors range from red and purple to green. Green v a r i e t i e s weather white or brown and weathered breccias and t u f f s are d i f f i c u l t to d i s t i n g u i s h from one another as weathering obscures t h e i r texture. 22 Sequences of interbedded breccias and thin bedded tuf f s make up most of the f e l s i t i c group. Other f e l s i t i c rock types are, greenish to purple coarse-bedded or massive t u f f , thin-bedded t u f f and feldspar porphyry flow. D i s t r i b u t i o n : F e l s i t i c volcanic breccias with some thi n interbedded t u f f s are the most abundant rocks of the map area. West, north and immediately east of Kinskuch Lake, these pyroclastics are interlayered with sedimentary beds and greenstone. East and south of the lake, Mount Lavender and i t s surrounding slopes are formed almost s o l e l y of f e l s i t i c breccia and t u f f . Massive breccias s t r e t c h east from Kinskuch Lake for some two miles, gradually passing into a thick sequence of overlying volcanic rocks, including coarse bedded or massive t u f f , f i n e bedded t u f f , and feldspar porphyry flow. Near the eastern edge of the map area, f e l s i t i c volcanic breccias underlie sedimentary rocks. Petrography: F e l s i t i c Volcanic Breccia: Most rock fragments i n f e l s i t i c breccias measure two inches to three inches across and are quite angular. These fragments are mainly of a highly feldspathic igneous rock. Some f e l s i t i c breccias are green, but other types, es p e c i a l l y those east of Kinskuch Lake have a fine-grained red matrix surrounding f e l s i t i c rock fragments. PLATE VI Red F e l s i t i c Breccia In a thin-section of a red f e l s i t i c breccia, the only i d e n t i f i a b l e o r i g i n a l mineral is plagioclase. C r y s t a l fragments of plagioclase, are unzoned and only s l i g h t l y s e r i c i t i z e d . Composition of this feldspar ranges from Ano to An^ but some crystals have posi t i v e r e l i e f and the i r composition is about An^o» Plagioclase fragments are surr-ounded by a dense reddish indeterminable matrix. Scattered through this red matrix are grains of opaque iron-oxide. Numerous veinlets containing c a l c i t e , sodic feldspar and probably some quartz cut through feldspars and matrix. Some of the sodic feldspar i n the veins i s twinned and blade-l i k e (Plate VII). In other veinlets feldspar forms a f i n e -grained mass of interlocking c r y s t a l s . Along parts of some of the v e i n l e t s , fresh vein feldspar i s i n o p t i c a l continuity with s e r i c i t i z e d plagioclase crystals bordering the v e i n l e t . PLATE V I I . 5 m.m. i i Photomicrograph of a v e i n l e t of c a l c i t e and sodic feldspar PLATE V I I I • « Photomicrograph of veinlet of c a l c i t e and fresh sodic feldspar bordering s e r i c i t i z e d plagioclase A p a r t i a l chemical analysis of the red f e l s i t i c breccia just described, i s shown below. The calculated normative minerals are also l i s t e d . TABLE III Oxide Weight Percentage Normative Minerals and percentages S i 0 2 61.0 Quartz 7.0 Al^O^+TiOg 17.9 Orthoclase. 2.0 F e 2 0 3 1.5 A l b i t e 51.5 FeO 4.8 Anorthite 20.0 MgO 1 .5 Diopside 11 .5 CaO • 6.8 Hypersthene 6.0 Na 20 6.1 Magnetite 2.0 K 20 0 .35 99.95 100.0 A l l the minerals calculated i n the norm, except feldspar and magnetite, must be represented i n the rock i n the indeterminable reddish groundmass and v e i n l e t s of c a l c i t e . In addition to the common type of f e l s i t i c breccia, described above, there is one type which i s r i c h i n horn-blende. In most specimens of the l a t t e r type, sedimentary rock fragments, mainly a r g i l l i t e and s i l t s t o n e , form about 20$ of the breccia. Fragments of c r y s t a l l i n e igneous rocks constitute another 30% of specimens. Most fragments i n 26 hornblende r i c h f e l s i t i c breccias measure about one inch across. These breccias are grey on a fresh surface, and white, where weathered. PLATE IX Hornblende r i c h f e l s i t i c breccia In a thin-section of hornblende r i c h breccia i t is seen that breccia fragments are of calcareous s i l t s t o n e and various types of indeterminable c r y s t a l l i n e igneous rocks. The l a t t e r fragments are composed mainly of s e r i c i t -ized plagioclase and some hornblende and potash feldspar. The c r y s t a l t u f f matrix surrounding fragments composes about 50% of the specimen. Crystals of green pleochroic hornblende, now almost completely altered to c h l o r i t e and b i o t i t e , form about 30% and subhedral plagioclase another 50%, of the 27 matrix. This plagioclase (Ang) is quite fresh except for certain zones which are altered to c h l o r i t e . The balance of the matrix consists of fine flakes of c h l o r i t e and small brown pa r t i c l e s of cry p t o c r y s t a l l i n e material. Coarse-bedded F e l s i t i c Tuff: - Handspecimens of coarse-bedded t u f f are green or purple and most are very fine-grained or contain a few small fragments of rock. Individ-ual beds, i n outcrops, are about 20 feet thick. S t r a t i -f i c a t i o n of beds of alternating color is apparent from a distance. PLATE X Coarse-bedded f e l s i t i c t u f f In a thin-section i t is seen that some of this massive t u f f has fragments measuring as much as 3 ni.m. across Rock fragments are composed of augite and highly altered indeterminable plagioclase phenocrysts i n a flow matrix. Crystal fragments forming the groundmass about the l a t t e r rock inclusions are augite, altered plagioclase and some b i o t i t e . The c r y s t a l t u f f groundmass forms Q0% of the specimen. Although some specimens of coarse-bedded f e l s i t i c t u f f may contain notable amounts of augite, the l a t t e r mineral is not v i s i b l e i n hand specimens. For purposes of f i e l d work, the c l a s s i f i c a t i o n of thi s type of rock as f e l s i t i c i s probably the most useful one. Thin-bedded F e l s i t i c Tuff: - Thin-bedded f e l s i t i c tuffs are composed of white c r y s t a l or rock fragments rang-ing i n size from microscopic up to one-quarter of an inch across. The fine-grained matrix surrounding white fragments is red i n color. In a l l of these t u f f s , bedding is well defined by bands a f r a c t i o n of an inch to fractions of a foot thick. PLATE XI Red, thin-bedded t u f f 29 In a thin-section of a fine-grained specimen of red t u f f i t is seen that most of the angular c r y s t a l grains measure .3 to .6 mm. across. These grains are mainly un-twinned plagioclase, highly altered by carbonate and s e r i c i t e . Staining shows that no potash feldspar is present. Minute reddish p a r t i c l e s and large opaque grains of iron-oxide surround c r y s t a l fragments. Purple to Green F e l s i t i c Tuff: - Purple and green f e l s i t i c t u f f s are massive but here and there they con-t a i n randomly di s t r i b u t e d rock fragments. In a specimen studied i n thin-section, the largest c r y s t a l fragments measure .2 mm. across. O p t i c a l l y p o s i t i v e grains of sodic plagioclase compose the major part of the rock and these feldspars are highly altered to mixtures of carbonate and s e r i c i t e . Grains of fresh potash feldspar., are a minor con-stituent of this t u f f . Thin veinlets of c a l c i t e and s e r i c i t e transgress the rock. Another p a r t i c u l a r l y fresh specimen of massive c r y s t a l t u f f i s seen i n thin-section to be composed mainly of euhedral plagioclase c r y s t a l s . These crystals, forming about 75% of the rock, have a rough flow-like alignment and their extinction angles, o p t i c a l l y positive sign and negative r e l i e f indicate a composition of An3» The matrix i n t e r s t i t i a l to these crystals i s composed of small ragged grains of plagio-clase and some c h l o r i t e , epidote, pyrite and carbonate. Quartz, epidote and carbonate vein the rock. A p a r t i a l chemical analysis of this fresh t u f f and the calculated norm i s as follows: TABLE TV Oxide Weight Percentage Normative Minerals and percentages S i 0 2 55.0 orthoclase 1.00 A l 2 0 3 + T i 0 2 20 .3 a l b i t e 52.5 2.4 anorthite 26.5 FeO 7.2 hypersthene • 6 .5 MgO 3.4 o l i v ine 9.5 CaO 5.4 magnetite 3.5 Na 20 6.2 K 20 .16 100.06 99.5 The amount of plagioclase indicated i n the norm agrees well with the percentage of feldspar noted i n t h i n -section. Assuming a l l the CaO i s contained i n plagioclase the composition of feldspar is A1133. In thin-section i t was seen that notable amounts of c a l c i t e and epidote are present and the composition of the feldspar i s i n fact Ans. Feldspar Porphyry Flows: - Type Number One: The f i r s t type of feldspar porphyry flow is greyish-purple with euhedral white feldspar phenocrysts and subhedral greenish-black mafic. Staining with HF etch and sodium c o b a l t i n i t r i t e indicates that there is very l i t t l e potash feldspar i n the rock. Under the microscope, the rock is seen to be highly altered. Phenocrysts are s e r i c i t i z e d plagioclase. Com-position of the l a t t e r could not be determined because of a l t e r a t i o n , but extinction angles indicate i t may be close to An^Q or AHQ. A few large pseudomorphs of c h l o r i t e and carbonate after hornblende are present. The groundmass is a mixture of anhedral grains of c h l o r i t e , carbonate, s e r i -c i t i z e d feldspar and apatite. Less than 5$ quarts i s present i n this matrix. Type Number Two: - A second v a r i e t y of feldspar porphyry, probably also a flow, outcrops only i n the northeast corner of the map, area and i t s relationship to other rocks is l a r g e l y unknown. This rock has a fine-grained greenish matrix enclosing large phenocrysts of white potash feldspar and smaller phenocrysts of plagioclase and mafic minerals. Potash feldspar phenocrysts have a flow-like orientation. In thin-section, a l l feldspars are quite fresh. Potash feldspar phenocrysts present smooth but somewhat irr e g u l a r boundaries against the groundmass. Some of these phenocrysts contain "i n c l u s i o n s " of plagioclase c r y s t a l s . (Plate XIII). Small phenocrysts of plagioclase with a PLATE XII Coarse feldspar porphyry flow PLATE XIII .5 num. i i Photomicrograph of phenocryst i n coarse feldspar porphyry 33 composition of Arig are also present i n the groundmass. The fine-grained matrix forming $0% of the rock is composed of anhedral grains of plagioclase, potash feldspar, and quartz. In a thin-section of a second v a r i e t y of this flow rock, the large phenocrysts are potash feldspar enclosing patches of plagioclase. A l l the plagioclase twin lamellae have the same orientation. (Plate XIV). Smaller feldspar phenocrysts are crystals of antiperthite apparently formed by potash replacing the soda of plagioclase. The matrix surrounding phenocrysts consists of anhedral grains of potash feldspar and quartz. Secondary mafic minerals in both v a r i e t i e s of this flow constitute about 10% of the rock. Mafic minerals are serpentine, c h l o r i t e , b i o t i t e and magnetite. Veinlets of serpentine which are accompanied by some brecciation of groundmass and phenocrysts, cut across the rock. PLATE XIV i - i Photomicrograph of patches of plagioclase i n potash feldspar phenocryst 34 A p a r t i a l chemical analysis of a specimen of coarse feldspar porphyry flow i s shown below. Normative minerals and their percentages are also l i s t e d . TABLE V Oxide Weight Percentage Normative Minerals and percentages sio 2 63 .50 Quartz 19 .5 A l 2 0 ^ + T i 0 2 17 .45 Corundum 6 . 0 FegO^ 2.07 Orthoclase 2 0 . 0 FeO 6 . 0 0 A l b i t e 3 2 . 0 MgO 2.57 Anorthite 4 .5 CaO .85 Hypersthene 15.5 Na 2 0 3 .80 Magnetite 3 . 0 K 2 0 3.39 99 .63 100 .5 Assuming a l l the CaO i s contained i n plagioclase, the composition of feldspar i s An^ 2. This composition i s very close to the value of Ang, determined i n thin-section. The amount of normative orthoclase points up the abundance of potash i n these rocks and supports the idea, derived from the study of thin-sections, that some soda i n feldspars has been replaced by potash. The amount of normative quartz i s probably a true i n d i c a t i o n of the percentage of t h i s mineral i n the rock. No corundum is present i n the rock and excess A1 2 0^ i n the norm must be represented i n other minerals. This flow has the composition of a quartz l a t i t e . 35 Reddish Color i n F e l s i t i c Rocks As described i n the l a s t sections on petrography, many of the f e l s i t i c fragmental volcanics have a f i n e -grained reddish groundmass. Red f e l s i t i c breccias and tu f f s are the predominant rocks east of Kinskuch Lake. Thousands of feet of such reddish breccia form Mount Lavender. In some specimens of the l a t t e r rocks, the white fragments themselves are rimmed just within t h e i r borders by a form of reddish a l t e r a t i o n (Plate XV"). In other places i n the same rocks, rather uniform reddish bands, apparently not controlled by fractures, cut the otherwise whitish breccia. (Plate XVI). In s t r a t i g r a p h i c a l l y lower zones of these breccias i r r e g u l a r v e i n l i k e masses of soft reddish material wind upward through green breccias towards red py r o c l a s t i c s . PLATE XV Red-rimmed fragments i n f e l s i t i c breccia PLATE X V I Red band i n f e l s i t i c breccia The reddish color of the veins and pyroclastic rocks is probably due to the presence of f i n e l y disseminated hematite. Certain features described above suggest the coloration may be a form of hydrothermal a l t e r a t i o n but i t s regular d i s t r i b u t i o n seems to indicate that the color i s an o r i g i n a l feature. The study of sedimentary red beds has shown that red coloration of rocks is i n d i c a t i v e of pre-valence of oxidation over reduction conditions at the s i t e of deposition. It is therefore possible that the red colors in volcanic rocks east of Kinskuch Lake are the result of deposition i n a sub-aerial environment. A l b i t i z e d Andesite-Greenstone Greenstones are massive green rocks which i n places 37 show flow structure (Plate XVII) and also a flow-like orien-ta t i o n of c h l o r i t e pseudomorphs after hornblende. But to a large extent, the rock mapped as greenstone i s a f i n e -grained, green t u f f . In the f i e l d , i t i s convenient to d i f f e r e n t i a t e these massive green rocks from those which show a d e f i n i t e fragmental texture. D i s t r i b u t i o n : Greenstone only outcrops over a r e l a t i v e l y small area along both sides of Kinskuch Lake. Here, massive green rocks overlie f e l s i t i c breccia to the west and underlie or are intercalated with f e l s i t i c breccias and sedimentary rocks to the east of the lake. Petrography: In hand-specimens these rocks are either massive green or c r y s t a l l i n e . C r y s t a l l i n e v a r i e t i e s have a green matrix surrounding darker green c h l o r i t e pseudo-morphs after hornblende. Under the microscope the matrix of a greenstone flow is seen to be a f e l t e d mass of f i n e grains of potash feldspar plagioclase and c h l o r i t e . Subhedral phenocrysts of plagioclase have a composition of An^ to Ang but more c a l c i c v a r i e t i e s are possibly present. Other phenocrysts are c h l o r i t e pseudomorphs after hornblende and these show p a r a l l e l orientation.- Apatite p y r i t e , carbonate and quartz are scattered throughout the rock i n small amounts. 38 PLATE XVII Flow structure i n greenstone Age Only two recognizable f o s s i l s were found i n the rocks of Kinskuch Lake area. These f o s s i l s were i d e n t i f i e d by Mr; W.R.Danner who reports as follows: Pelecypod - one impression of Pseudomonotis sp. Corals - remnants of a colony Isastrea sp. - resembles 1* profunda more than i t does I. vancouverensis The rock containing the pelecypod was part of an a r g i l l i t e - volcanic breccia sequence near the base of sedimentary formations at the eastern edge of the map area. The coral was a fragment i n a f e l s i t i c volcanic breccia and although the rock was f l o a t , i t was apparently derived from sim i l a r beds nearby. The l a t t e r beds are f e l s i t i c breccias which underlie sedimentary rocks west of Kinskuch Lake. Mr. Danner states that the two f o s s i l s which were described i n the previous section, are common i n the Upper T r i a s s i c of the P a c i f i c coast and western C o r d i l l e r a n area. The lack of f o s s i l s makes i t impossible to date the majority of the rocks at Kinskuch Lake with any degree of assurance. The f o s s i l s described above suggest that some beds are possibly Upper T r i a s s i c i n age and Hanson indicates that sedimentary rocks east of the head of the Ki t s a u l t River are either Jurassic or Cretaceous. It i s possible therefore that the rocks of Kinskuch Lake area were deposited through a large part of the Mesozoic. Correlation As defined by Leach, i n 1910, the term Hazelton Group included a l l Mesozoic rocks older than the Coast intrusions. Hanson c a l l e d the Mesozoic rocks of A l i c e Arm d i s t r i c t Hazelton group as he believed the volcanic rocks of Portland Canal area were: 40 si m i l a r i n age and l i t h o l o g i c a l character to those of the porphyrite group of Dawson and the Hazelton group of Leach (1935 9 p. 4 ) . Mesozoic sedimentary and igneous rocks, probably large l y Jurassic i n age, extend south from Portland Canal area to the Skeena River and beyond. Similar successions of volcanic and sedimentary rocks, which are of Mesozoic Age have been described i n southeast Alaska by Buddington and Chapin (1929) and to the north along the lower S t i k i n e and Western Iskut River areas by Kerr and Coake (1948) . Buckham and Latour (1950) working i n the groundhog d i s t r i c t east of Portland Canal area outlined Middle Jurassic to Lower Cretaceous sedimentary rocks and suggested the term Hazelton Group should be r e s t r i c t e d to beds of this age. Mesozoic volcanic and sedimentary rocks s i m i l a r to those of Portland Canal Area are apparently widely d i s -tributed throughout southeastern Alaska and western B r i t i s h Columbia. In most places the age of these sedimentary igneous successions is not d e f i n i t e l y known and th e i r c o r r e l a t i o n l o c a l l y and regionally is very d i f f i c u l t . Intrusive Rocks Dykes and s i l l s are present i n great numbers along the western side of Kinskuch Lake but elsewhere i n the map area, intrusions are not abundant. Most dykes and s i l l s are from 5 to 30 feet wide but some intru s i v e bodies measure as much as 350 feet across. The l a t t e r bodies are feeders of the many smaller dykes and s i l l s . Stock-like plutons are present i n very few places. The largest of the stocks covers about one-quarter square mile. The composition of intrusions range from acid keratophyric v a r i e t i e s to basic lamprophyres. The d i f f e r e n t types distinguished, namely hornblende keratophyre, kera-tophyre and quartz keratophyre, quartz feldspar porphyry, augite quartz d i o r i t e and lamprophyre w i l l be discussed i n the order above, which i s also t h e i r order i n age from oldest to youngest. Hornblende Keratophyre Hornblende keratophyre is the most abundant and probably the oldest type of i n t r u s i v e . West of Kinskuch Lake, hornblende keratophyre dykes and s i l l s , fed by a 350' wide feeder, s t r i k e eastward through sedimentary rocks, f e l s i t i c breccia and greenstone. East of the lake, the dykes do not pass through massive f e l s i t i c breccia. Possibly a f a u l t cuts the intrusives o f f , or they may pass beneath the breccias, not intruding them, because of the massive, competent character of the volcanic rocks. PLATE XVIII Hornblende keratophyre feeder viewed from the west Megascopically, hornblende keratophyre i s com-posed of euhedral hornblende crystals i n a fine-grained matrix of white weathering feldspar and mafic minerals. In most specimens the hornblende has flow-like orientation. Rock inclusions are common. In di f f e r e n t v a r i e t i e s of hornblende keratophyre, the amphibole and feldspar become very coarse or very f i n e -grained. A l l gradations of hornblende keratophyre probably exist between hornblende porphyry and feldspar porphyry. The microscopic characters of two types of hornblende kera-tophyre are described i n the following section. Type Number One: - Euhedral crystals of green pleochroic hornblende crowded with feldspar inclusions, form about 30$ of the section. Hornblende phenocrysts, somewhat 43 altered to b i o t i t e and c h l o r i t e , are surrounded by smaller anhedral grains of plagioclase and fine-grained potash feldspar. The l i g h t l y s e r i c i t i z e d and c h l o r i t i z e d plagio-clase crystals form about 50% of the rock. Only a few grains show a l b i t e twinning but others which are twinned have negative r e l i e f and extinction angles indicating a composition close to AnQ. Some apatite, quartz and carbonate are present i n the specimen. PLATE XIX .5 m.m. • Photomicrograph of hornblende keratophyre Type Number Two: - About 50% of the rock i s composed of large euhedral feldspar c r y s t a l s , close to a l -bite i n composition. The matrix, which forms about 30% of the specimen, consists of anhedral grains of potash f e l d -spar, plagioclase and c h l o r i t e . Euhedral pseudomorphs of c h l o r i t e , carbonate and epidote after fine-grained horn-blende form another 15$ of the rock. Apatite i s abundant. Keratophyre, Quartz Keratophyre Keratophyre, quartz keratophyre dykes cut horn-blende keratophyre types. In hand-specimen the groundmass is greenish grey and on staining this proves to be potash feldspar, fine grains of mafic and quartz. This matrix forms 50$ of the rock. The remaining constituents of the specimen are euhedral crystals of plagioclase feldspar and anhedral mafic grains forming 35$ and 15$ respectively. In thin-section, subhedral laths of plagioclase have a composition of about An^ to An-^ Q. This feldspar i s partly altered to c h l o r i t e , carbonate and a white opaque mineral. The matrix i s a rather close f e l t e d mesh-work of micro l i t e s of potash feldspar, needles of green, s l i g h t l y pleochroic a c t i n o l i t e , and f i n e grains of c h l o r i t e , epidote and quartz. Large grains of a c t i n o l i t e , c h l o r i t e , quartz and carbonate and small opaque grains of magnetite are also present i n the groundmass. In a section of a similar dyke, which i s more highly altered, there is up to 2 0 $ quartz present. This quartz may be secondary. 45 Quartz-Feldspar Porphyry Quartz-feldspar porphyry dykes were seen at only a few places and their age with respect to other intrusives is not known. In hand specimens a fine-grained light' green matrix surrounds quartz and feldspar phenocrysts. S t a i n -ing shows that 20% of the rock is quartz and the remainder is plagioclase. Under the microscope, i t i s seen that rounded quartz phenocrysts are ringed and embayed by zones of intermixed fine grained quartz and feldspar. These zones grade into the matrix of fine grains of anhedral plagioclase. Subhedral phenocrysts of feldspar have a composition of An 1 0 . Augite Quartz D i o r i t e A stock of augite quartz d i o r i t e intrudes rocks at the southeast corner of Kinskuch Lake. The age of this stock with respect to intrusive: types already described, is not known. The texture of th i s rock i s medium-grained, g r a n i t i c and the color i s l i g h t green. Staining shows that the major components of the rock are 40% plagioclase, 20% potash feldspar and 15% quarts. The remaining constituents are anhedral grains of augite, needles of a c t i n o l i t e and fine grains of magnetite. 46 In thin-section, s e r i c i t e - a l t e r e d laths of zoned plagioclase form a network which encloses other minerals. Because of a l t e r a t i o n the feldspar cannot be definitely-i d e n t i f i e d . A few edges of plagioclase crystals have p o s i t -ive r e l i e f . E x t i n c t i o n angles indicate a composition as c a l c i c as An^o« T t i e anhedral mafic grains are colorless augite. C h l o r i t e , epidote, b i o t i t e and magnetite are assoc-iated with the pyroxene. In some specimens the a l t e r a t i o n of pyroxene is more pronounced and a c t i n o l i t e and epidote replace augite. Quartz and potash feldspar are present as anhedral grains embaying plagioclase. In one specimen, potash f e l d -spar forms rather euhedral c r y s t a l s . In the l a t t e r rock some of the plagioclase i s remarkably fresh and unzoned. Quartz-calcite veinlets cut the rock and where they trans-gress s e r i c i t i z e d feldspar, the feldspar is freshened i n the zone cut by the v e i n l e t . This fresh plagioclase has negative r e l i e f with respect to quartz and i s a sodic v a r i e t y . PLATE XX .5 m.m. Veinlet of quartz, c a l c i t e and sodic feldspar cutting s e r i c i t i z e d plagioclase c r y s t a l Lamprophyre A l l of the dykes mapped as lamprophyre are not tr u l y lamprophyric as some types do not have porphyritic mafic constituents. Lamprophyre cuts a l l other types of intrusions. Four v a r i e t i e s of lamprophyre are described i n the following sections. Type Number One: - This f i r s t variety of lampro-phyre occurs as a 30-foot wide dyke. The central part of this dyke is r e l a t i v e l y coarse-grained as compared to the margins. A d i s t i n c t i v e feature of thi s intrusive body i s the presence of segregation veinlets r i c h i n feldspar and long hornblende needles (Plate XXI). The l a t t e r segregation bands which are up to one-half inch wide are spaced at one foot intervals across the dyke and run p a r a l l e l to i t s borders for many feet. 48 A hand-specimen of the central portion of this lamprophyre dyke i s composed of equal amounts of medium-grained, anhedral brown mafic minerals and white feldspars. The microscopic characters of the coarser, finer-grained and segregation band portions, of thi s dyke, are discussed below. In a specimen from the coarser-grained part of the dyke, long, narrow interlocking laths of plagioclase (A1130) form about 60$ of the rock. I n t e r s t i t i a l to the feldspars and forming 10% of the rock i s a low r e l i e f mineral which is possibly a n a l c i t e . Anhedral grains of augite and b i o t i t e each constitute 10$ of the specimen, magnetite forms 5$ and apatite and other minerals make up the remainder. The finer-grained portion of the dyke i s composed of 50$ plagioclase (An^ Q), 35$ hornblende and b i o t i t e and small amounts of augite and apatite etc. In a specimen of a segregation band, the feldspars are short and stubby compared to those forming the other parts of the dyke. The composition of thi s plagioclase is An 2^. Thin euhedral crystals of brown pleochroic hornblende are abundant. Some b i o t i t e , magnetite and needle-like apatite crystals are the remaining constituents of the segregation band. 49 10 PLATE XXI White segregation band i n lamprophyre Type Number Two: - In a hand-specimen of the second type of lamprophyre, a fine-grained dark brown matrix surrounds large, yellowish euhedral feldspar c r y s t a l s . A thin-section shows a sub-radiating network of small plagio-clase laths forming 5 0 $ of the rock. The remainder of the groundmass, forming another 40$ of the specimen, i s f i n e anhedral grains of chinopyroxene, magnetite, b i o t i t e , ser-pentine and carbonate. Set i n this fine-grained matrix and forming the remaining 10$ of the rock are large plagioclase crystals having a composition near An^Q. Type Number Three: - Dykes of the t h i r d type of lamprophyre are present i n somewhat greater numbers than those of the two types already described. 50 These t h i r d types are fine-grained, dark greyish-green and highly amygdaloidal. As seen i n thin-section, the very fine-grained constituents, forming at least 80% of the rock, are radiating laths of highly altered feldspar, green mica, b i o t i t e , apatite and an opaque white a l t e r a t i o n . Amygdules of c h l o r i t e form the remaining 20% of the rock. Type Number Four: - The fourth type is the most abundant type of lamprophyre. This type is fine-grained dark green to dark grey with a few small, white, feldspar l a t h s . It i s seen under the microscope that the groundmass forming about 70% of the rock i s composed of sub-parallel feldspar microlites and fine-grained magnetite. This groundmass encloses a few larger lath-shaped c r y s t a l s , now wholly altered to carbonate, which were formerly feldspars. Some amygdules of c h l o r i t e and carbonate are present i n the matrix. Discussion of A l b i t i z a t i o n Conclusions It is d i f f i c u l t to estimate the extent to whieh the sodic feldspars, seen i n many of the igneous rocks, are of primary or secondary derivation. The occurrence of sodic feldspar, c a l c i t e , quartz and other minerals i n v e i n l e t s and vesic l e s strongly suggests that chemically complex solutions have moved through most of the rock. Evidence from t h i n -sections indicates that introduced soda has possibly been 51 exchanged for calcium i n plagioclase c r y s t a l s . According to C F . Parks, J r . , (194-8 p. 320), Eskola has performed experiments i n which c a l c i c feldspar was transformed into a l b i t e i n the following manner: Na 2C0 3 + CaAlSi 20g + 4 S i 0 2 • CaC0 3 + 2NaAlSi 30g Anorthite A l b i t e This reaction was observed to take place over a temperature range of 264°C to 331°C. In any veinlets containing sodic feldspar, the l a t t e r mineral is c l o s e l y associated with c a l c i t e . Where rocks are cut by these v e i n l e t s , i t i s possible that plagio-clase has been a l b i t i z e d i n a reaction s i m i l a r to that de-scribed by Eskola. A medium r i c h i n Na 20, C0 2 and S102 attacked the rocks, bringing about the p a r t i a l a l b i t i z a t i o n of the rock feldspars and a consequent formation of calcium carbonate. Bailey and Grabham (1909) discuss the a l b i t i z a t i o n of basic feldspar i n some carboniferous lavas of Scotland and they put forward a similar idea regarding the r e l a t i o n -ship of sodic feldspars and c a l c i t e i n a l b i t i z e d rocks. With regard to the association of carbonate and feldspar Bailey and Grabham state: 52 Epidote occurs not uncommonly i n small amounts i n the v e s i c l e s and groundmass of these a l b i t i z e d rocks, but not i n the feldspars themselves. It doubtless contains part of the lime removed from the feldspars but most of this l a t t e r has probably been carried off i n solution as calcium carbonate. (1909, p. 254) . Flows and intrusives r i c h i n sodic feldspar are said to be of s p i l i t i c a f f i n i t y . Such rocks are supposedly c h a r a c t e r i s t i c of sub-marine igneous a c t i v i t y associated with the deposition of geosynclinal sediments, however, G i l l u l y (1935) states that: This locus in not esse n t i a l for t h e i r development and many are sub a e r i a l . (1935 P. 252) . Although the rocks near Kinskuch Lake are mainly fragmental volcanics, certain types have ch a r a c t e r i s t i c s of rocks of s p i l i t i c association, especially with regard to a high Na 2 0 to low K 2 0 r a t i o i n their chemical composition. Source of A l b i t i z i n g Media There is much controversy concerning whether s p i l i t e s are of primary or secondary o r i g i n . Those who say s p i l i t e s have a secondary o r i g i n also question whether: (1) the replacing soda i s of hydrothermal o r i g i n , and (a) a u t o l y t i c or (b) derived from outside the a l b i t i z e d rocks. (2) the replacing soda i s derived from sea waters. 53 Bailey and Grabham suggest that a l b i t i z a t i o n of flows is a process of autolysis by residual solutions. Regarding the p o s s i b i l i t y of autolysis with hydrothermal solutions, G i l l u l y , s a y s This seems to require volumes of s o l u t i o n whose presence i f e n t i r e l y indigenous would be expected to be revealed by vugs combey c a v i t i e s and other evidences of the volume they occupied. Also evidence generally points to reactions being younger than groundmass consolidations. ( 1 9 3 5 , P. 3 4 3 ) . G i l l u l y sums;up his conclusions on the subject of s p i l i t i c rocks by saying The suggestion of Daly that the abundant soda of s p i l i t e s has been concentrated from an underlying mass of ba s a l t i c magma, through the action of resurgent water, i n conjunction with Goldschmidt's outline of trondhjemitic d i f f e r e n t i a t i o n , s a t i s -f a c t o r i l y accounts for most of the features of s p i l i t i c rocks. ( 1 9 3 5 , P. 3 4 6 ) . G i l l u l y i s of the opinion that a l l s p i l i t i c rocks are not of primary o r i g i n , but.he also states This does not ... exclude a magmatic o r i g i n for the p e c u l i a r i t i e s of the rocks. ( 1 9 3 5 , P. 249). Considering G i l l u l y ' s conclusions, outlined above, i t is possible to suggest that solutions r i c h i n Na 2 0 j C 0 2 and S 1 0 2 , which were introduced into rocks near Kinskuch Lake, were related to residual segregations evolved i n the cry-s t a l l i z a t i o n of the Coast intrusions. With regard to the 54 l a t t e r suggestion i t i s interesting to note that Knopf (1912) describes certain igneous rocks of the Juneau belt which are altered to a l b i t e and other minerals. Knopf relates the metasomatic a l t e r a t i o n to vein forming solutions of deep seated o r i g i n . S t r u c t u r a l Geology The present information on the geology of the area is not s u f f i c i e n t to give a complete s t r u c t u r a l picture. The rather complex and variable nature of in t e r f i n g e r i n g s e d i -mentary and volcanic rocks make i t d i f f i c u l t to correlate various sequences for any distance. Folding Near the southwest corner of the map area, s e d i -mentary rocks and overlying augite porphyry volcanics are folded into a north-plunging a n t i c l i n e . F e l s i t i c volcanics and a r g i l l i t e , overlying a u g i t i c rocks, s t r i k e north to northwest and dip eastward. Sedimentary rocks along the west side of Kinskuch Lake form another north-plunging a n t i c l i n a l f o l d . At the north end of the lake and immediately to the east of i t , small patches of folded a r g i l l i t e and limestone are overlain by f e l s i t i c volcanic breccia. - East of Kinskuch Lake eastward-dipping f e l s i t i c breccia grades into f e l s i t i c t u f f s and flows showing minor contortions and some west dips, but predominant east dips. Further east, i n t e r f i n g e r i n g 55 f e l s i t i c breccias and t u f f s show many west dips and a south-plunging syncline is indicated. At the eastern contact with sedimentary rocks, fragmental volcanics dip eastward, beneath a r g i l l i t e s and conglomerates. (see Figure II i n pocket). Hanson's map shows that the volcanic rocks d i r e c t l y south of the l a t t e r region are folded into a south-plunging syncline and north-plunging a n t i c l i n e . Faulting Topographic indications of faul t s are many, i n the form of low g u l l i e s , v a l l e y s , r i v e r s and streams and offset s t r a t a . Most of the l a t t e r features are v i s i b l e from a e r i a l photographs. Only a few faults show measurable movements and no actual f a u l t surfaces were seen. The straight or s l i g h t l y curving path of most breaks suggest that they are steep dipping. In the case of at least two f a u l t s , horizontal offsets of the order of 1000 to 2000 feet are indicated but the v e r t i c a l component is unknown. Some dykes are offset along f a u l t s about 50 feet, but this displacement may not represent the t o t a l movement on the f a u l t . The trends of the two main types of faults are e a s t - s t r i k i n g and northeast-striking. East s t r i k i n g f a u l t s , i n general appear to be e a r l i e r than the other types, and are both right hand and l e f t hand. Northeast-trending f a u l t s show l e f t hand movements and In some places i n the area, cut east-trending f a u l t s . Throughout the area, shears and fractures have trends similar to those of large breaks. Stereographic plots were made of poles of veins and shears cutting rocks of the altered zone, (Figures III and IV i n Pocket). These plots show that the majority of veins s t r i k e east and.dip steeply north and south. Many shears i n the rocks s t r i k e northwest and.dip steeply northeast and southwest and smaller numbers s t r i k e northeast, dipping northwest at moderately high angles. Faulting offsets keratophyre and lamprophyre dykes and i t is probable therefore that some or a l l of the f a u l t i n g was l a t e . 57 CHAPTER IV ECONOMIC GEOLOGY Introduction A prominent crescent-shaped zone of a l t e r a t i o n and copper mineralization borders the southeast corner of Kinskuch Lake and covers an area of approximately two-square miles. Outcrops of altered rocks, about one mile south of the main zone near the lake, indicate that a l t e r a t i o n and mineralization may also extend under ice and snow to thi s southern l o c a l i t y . The main zone was investigated by diamond d r i l l i n g , sampling and detailed mapping i n order to determine the value of i t s mineral content. Highly sheared rocks of the zone near the lake are impregnated with disseminated pyrite and minor chalcopyrite and are cut by quartz-carbonate veins carrying p y r i t e , chalcopyrite and traces of galena and sphalerite. A l t e r -ation minerals associated with mineralization are c h l o r i t e , epidote, s e r i c i t e , c a l c i t e , quartz and some sodic feldspar. A stock of p a r t i a l l y altered augite quartz d i o r i t e outcrops near the centre of the altered mineralized zone. 58 M i n e r a l i z a t i o n Disseminated Disseminated chalcopyrite occurs as blebs d i s t r i -buted through parts of the p y r i t i z e d - c h l o r i t i z e d rocks. The fineness of chalcopyrite and pyrite and t h e i r s i m i l a r appearance where tarnished make i t d i f f i c u l t , at f i r s t glance, to d i s t i n g u i s h between the two sulphides. Some outcrops are stained by malachite but the presence of this green s t a i n does not prove to be a guide to copper content of the rock. In general, i t can be said that the occurrence of chalcopyrite i s r e s t r i c t e d to c h l o r i t e - p y r i t e rocks but within such rocks, the d i s t r i b u t i o n of copper mineralization is e r r a t i c and unpredictable. Outcrops containing dissemin-ated chalcopyrite are shown on the map as c h l o r i t e - p y r i t e -chalcopyrite rocks. Diamond d r i l l i n g and assaying of chl o r i t i z e d - p y r i t i z e d - r o c k s showed that the highest copper grades occur near the surface and these grades are lower at quite shallow depth. Holes d r i l l e d at lake l e v e l penetrated and passed through the best copper mineralization i n about 3 0 0 v e r t i c a l feet. In polished-sections of rocks containing dissemin-ated mineralization, blebs of pyrite and chalcopyrite are for the most part widely separated from one another. Where the two minerals are i n contact, chalcopyrite f i l l s fractures i n pyrite grains or is molded onto the l a t t e r . 59 Vein Numerous veins cut a l l v a r i e t i e s of altered rocks, i n various parts of the altered-mineralized zone. The majority of these veins are about two feet wide but others measure up to f i v e feet across. Some of the larger veins can be traced along s t r i k e for distances up to 1000 feet. The attitude of most veins, as shown i n Figure III ( i n pocket) is e a s t - s t r i k i n g , dipping steeply north or south. Veins are of two main types, quartz and quartz-carbonate and the majority are barren of sulphide or carry only p y r i t e . Some quartz-carbonate veins are l o c a l l y r i c h , containing massive chalcopyrite and pyrite as one-foot-long lenses. At least one vein contains p y r i t e , chalcopyrite and also some galena and sphalerite disseminated over a length of about 20 feet. In polished-sections of vein specimens, galena sphalerite and chalcopyrite are seen to be younger than p y r i t e , and molded around the edges of the l a t t e r mineral. Galena is replaced by sphalerite and both of these are re-placed by chalcopyrite. Much of the sphalerite contains minute inclusions of chalcopyrite and i n some grains, blebs of chalcopyrite form a gr i d pattern of straight l i n e s . The chalcopyrite that occurs as minute inclusions i n sphalerite has probably been exsolved. The paragenetic sequence of vein minerals is as follows: 60 1. Pyrite 2. Galena 3. Sphalerite with exsolved chalcopyrite 4. Chalcopyrite There is l i t t l e evidence regarding the r e l a t i o n s h i p between disseminated minerals and vein minerals. In„;both types of mineralization, chalcopyrite i s l a t e r than p y r i t e . It i s possible that much of the disseminated chalcopyrite and pyrite were introduced by the vein forming solutions. A l t e r a t i o n The various types of a l t e r a t i o n shown on the map are chlorite-pyrite-carbonate quartz, c h l o r i t e - p y r i t e - e p i d o t e , c h l o r i t e - p y r i t e - c h a l c o p y r i t e and s e r i c i t e - p y r i t e . Chlorite-pyrite-carbonate quartz a l t e r a t i o n is widespread over most of the altered mineralized zone. Locally epidote or chalcopyrite is present i n notable amounts i n these rocks and carbonate a l t e r a t i o n becomes very strong adjacent to quartz-calcite veins. Near the eastern and western fringes of the altered zone, s e r i c i t e - p y r i t e a l t e r a t i o n is predominant. The most s t r i k i n g example of s e r i c i t i z a t i o n i s found 1000 feet above and 2000 feet east of the lake. Here, s e r i c i t i c a l t e r -ation takes the form of a layer, roughly conformable 61 with bedding, about 500 feet thick and 2000 feet long. This mass of s e r i c i t i z e d rock gradually fingers out as t h i n bands of s e r i c i t i z a t i o n along fractures and passes into c h l o r i t e -pyrite-carbonate a l t e r a t i o n . Hand specimens of c h l o r i t i z e d - p y r i t i z e d rocks have a dark green matrix enclosing scattered grains of p y r i t e . In some specimens of altered volcanic breccia and t u f f s , the fragmental texture i s preserved by c h l o r i t i c re-placement of rock fragments. Other specimens have a c r y s t a l -l i n e texture with chlorite-carbonate pseudomorphs afte r hornblende c r y s t a l s . In thin-section c h l o r i t e appears as ragged scattered grains between highly s e r i c i t i z e d f e l d -spars. C h l o r i t e forms about 20$ of these rocks, pyrite 10$. In some specimens chalcopyrite or epidote accompany c h l o r i t e and p y r i t e . Heavily s e r i c i t i z e d rocks are rusty yellow to grey and crumbly or clayey. Hand specimens consist of fine-grained s e r i c i t e and granular quartz enclosing cubes and grains of p y r i t e . Under the microscope, this rock i s seen to be composed of a fine-grained mixture formed of 50$ quartz and feldspar and 40$ s e r i c i t e and some carbonate. A small amount of apatite is also v i s i b l e and i n some specimens granular or cubic pyrite composes 10$ of the rock. 62 Genesis of Mineralization and A l t e r a t i o n The fact that quartz-carbonate-sulphide veins cut the altered rocks suggests that a l t e r a t i o n was i n part e a r l i e r than mineralization but i t i s probable that the two processes were cl o s e l y related and possibly contemporaneous. Two factors apparently r e s t r i c t e d l o c a l i z a t i o n of a l t e r a t i o n and mineralization . The most important factor was the o r i g i n a l rock composition. The greater part of c h l o r i t e - p y r i t e a l t e r a t i o n is confined to greenstone and possibly some hornblende keratophyre dykes. The main zones of s e r i c i t e - q u a r t z - p y r i t e a l t e r a t i o n are probably confined to rocks which were o r i g i n a l l y f e l s i t i c pyroclastics and at one point, well bedded f e l s i t i c fragmental volcanics pass gradationally into highly s e r i c i t i z e d rocks. A second factor l o c a l l i z i n g a l t e r a t i o n and mineralization was the highly shattered character of the altered rocks, which allowed entrance of the necessary solutions. Beyond i t s centralized p o s i t i o n i n the altered zone, the augite quartz d i o r i t e stock shows no s i g n i f i c a n t r e l a t i o n s h i p to a l t e r a t i o n and mineralization. Certain evidence is available concerning the time of a l t e r a t i o n and mineralization. Some lamprophyre dykes cut the altered rocks but other such dykes are veined by quartz and carbonate containing some py r i t e and chalcopyrite 63 Some quartz-carbonate veins are offset along small north-trending f a u l t s . A l t e r a t i o n and mineralization was appar-ently l a t e but did precede some of the la t e s t f a u l t i n g . The type of a l t e r a t i o n and mineralization that has been described above is s i m i l a r to that present i n the "copper b e l t " rocks of the upper K i t s a u l t Valley west of Kinskuch Lake. Hanson, i n describing the copper belt rocks states: The rocks of the Copper Belt proper, compared with the other igneous rocks of the area are highly sheared and much altered to, or replaced by such minerals as s e r i c i t e , c h l o r i t e , c a l c i t e and p y r i t e . The belt consists c h i e f l y of fine-grained, f r a g -mental volcanic rocks and of c r y s t a l l i n e rocks that are probably mainly i n t r u s i v e . In places the rocks could not be i d e n t i f i e d as c e r t a i n l y either massive or fragmental ... The rocks are not d i f f e r e n t i n mineral composition from the other rocks of the area, but the belt i s distinguished by the presence of copper deposits, by the sheared nature of the rock and by the universal presence of p y r i t e . (1935 P. 39) Conclusion At the present time the mineral deposit at Kinskuch Lake does not seem to be of economic grade and s i z e . Rock mineralized with disseminated chalcopyrite occurs over a f a i r l y large area but is of very low-grade. Veins are also low-grade and of l i t t l e importance. Extensions of the altered-mineralized zone may exist and these could con-ceivably be of economic grade. 64 BIBLIOGRAPHY B a i l e y , E.B., and Grabham, G.W., A l b i t i z a t i o n o f B a s i c P l a g i o c l a s e F e l s p a r s . G e o l o g i c a l Magazine Volume V I , 1909, p. 250-256. B l a c k , J.M., B.C.Department o f Mines Report 1951, p. 76-109 Buckham, A.F., and L a t o u r , B.C., - Groundhog C o a l F i e l d , B.C., G.S.C. B u l l e t i n 16, 1950, p. 14-18. B u d d i n g t o n , A.F., and C h a p i n T., Geology and M i n e r a l D e p o s i t s o f S o u t h E a s t A l a s k a . U.S.G.S. B u l l . 800, 1929, p. 130-231. Dewey, H. and F l e t t , J.S., Some B r i t i s h P i l l o w Lavas and A s s o c i a t e d Rocks. G e o l o g i c a l Magazine, Volume 8, 1911, p. 202-209 and 241-248. G i l l u l y , J . , E a s t e r n Oregon and t h e S p i l l i t e Problem. P a r t I - American J o u r n a l o f Science,- Volume 29, 1935, P. 225-252. P a r t I I - American J o u r n a l o f S c i e n c e , Volume 29, 1935, P. 336-352. Hanson, G., P o r t l a n d C a n a l D i s t r i c t B r i t i s h C o l u m b i a , G.S.C. Memoir 175, 1935, P. 1-51. R e c o n n a i s s a n c e between K i t s a u l t R i v e r and Skeena R i v e r , B.C., G.S.C. Summary Repo r t 1922, P a r t A, p. 35-50. K e r r , F.A., ( c o m p i l e d by H.C. Cooke), Lower S t i k i n e and Western I s k u t R i v e r A r e a s , B.C., G.S.C. Memoir 246, 1948 - p. 24-35. Knopf, A., E a g l e R i v e r R e g i o n , S o u t h - E a s t A l a s k a , U.S.G.S. B u l l e t i n 502, 1912, p. 1-32. M c C o n n e l l , R.G., P o r t i o n s o f P o r t l a n d C a n a l and Skeena M i n i n g D i v i s i o n s , " Skeena D i s t r i c t , B.C., G.S.C, Memoir 32, 1913, p. 1-27. P a r k s , C F . J r . , The S p i l i t e and Manganese problem o f t h e Olympic P e n n i n s u l a , Washington. American J o u r n a l o f S c i e n c e , V o l . 244, 1946, p. 305-324. P i r s s o n , L.V., M i c r o s c o p i c C h a r a c t e r s o f V o l c a n i c T u f f s , A merican J o u r n a l of S c i e n c e , Volume 40, 1915, P. 195. F I G U R E I Mt. Lavender 76€o' - \ — Kinskuch Lake375o' B CROSS SECTION ALONG LINE A - B OF MAP VERTICAL AND HORIZONTAL S C A L E P - 2 0 0 0 ' DATUM LINE A-B - 2 5 0 0 1 ABOVE SEA LEVEL R E G . | 9 5 7 1 F I G U R E 1 2 / NORTH FIGURE I PORTLAND CANAL AND ADJACENT AREAS KINSKUCH LAKE AREA-INSET FIGURE I Mt. Lavender 76C01 CROSS SECTION ALONG LINE A-B OF MAP VERTICAL AND HORIZONTAL SCALE I" = 2000' DATUM LINE A-B - 25001 ABOVE SEA LEVEL F I G U R E M STEREOGRAPH 1C PLOT ON UPPER HEMISPHERE OF POLES TO ISO VEINS I | 0 - 1 % cnni 1 - 2 % 3- 4% 4 - 5% 2 - 3 % 5 - 6 % R.E.G. 1957 

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