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UBC Theses and Dissertations

Geology and mineral deposits of the eastern contact of the coast range batholith Black, James Murray 1936

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mmm I AED MINERAL DEPOSITS OF THE EASTERN CONTACT of th® , ': COAST BATHOLITH THESIS b y JAMES ffiJHRAY BLACK, B.A.Sc. Department of Geology Faculty of Applied. Science University of Br i t i sh Columbia A p r i l 1936 TABLE OF OOMEEMa CD Chapter Is Introduction Introduction. . . . . . . . . . Page 1 Area and Access ib i l i ty . . . . . . . . . . . . . . . . . 1 Climate • • ....... • • • ......... 2 Agriculture .......... 3 Field, work • 3 Acknowledgment • • • • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Chapter 2$ physiography Relation of Contact to Topography . . . « 5 Coast Range • ...... .. • ................ 5 Interior Plateaux ...... 6 Drainage • . . . . . . . . . . . . 7 Chapter 3s General Geology Introduction 8 pre-Cambrian ....... ......................... ••••• 8 (a) Tukon-Atlin .... 8 Devonian? Gold Series • • 10 (a) Yttkon-Atlin 10 Devonian? f a k u Group ........ • ••« 12 (a) Ytekon-Atlin 12 Upper Palaeozoic 13 (a) Yukon-Atlin . • 13 (b) Taku-Iskut •• 14 (c) Xskut Zymoetz »••..........* .................. 16 (dl Zymoetz River to Gun Creek • • 16 (e) Gun CreekrFraser River ........ 17 (11) Permian • • • Page 18 Sriassio • • • • 18 (a) Yukon-Atlin 18 (b) Taku-Iskut 19 (c) Iskut-Zymoetz .. .. •• • 20 (dl Zyraoetz-Gun Creek ••......••*•• .• 20 (e) Gun Creek-Fraser River • 21 Jurassic • 23 (a) Yukon-Atlin 23 (b) Taku-Iskut • • 25 (c) Iskut-Zymoetz •••• •••••..«.«•••••.••• • • 25 (d) Zymoetz-Gun Creek ...» •« • 27 (e) Gun Creak-Fraser River ......................**.... 29 Batholithio Intrusive Rocks • • • 30 (a) General ••.••••••»...*..•« 30 (b) Pre-Silurian « ... 30 (c) Pre-Triassic • ••• • »• 31 (d) Pre-Jurassic • • •• ••»•••••• 31 (e) Upper Jurassic Intrasives • 33 (f) Post-basal lower Cretaceous ••....».* •••••• , 34 (g) Lithology 36 (hi Altitude of Contact 40 (i) Contact Met amor phi sm 42 (•J) Method of Intrusion ( 1 1 1 1 Cretaceous • Page 43 (a) Taku-Iskut • 44 (b) Iskut-Zymoetz 44 (c) Zymoetz-Gun Creek • • • 45 (d) Gun Creek-Fraser River .... 46 Eocene 4? (a) Taku-Iskut • • 47 post-Eocene Flows • ................. 48 (a) Yttkon-Atlin 48 (b) Taka-Iskut 49 (c) Iskat-Zymoetz River 49 (d) Zymoetz River-Gun Creek ...» 49 (e) Gun Creek-Fraser River 50 Pleistocene and Recent 50 Chapter 4J Structural Geology • • 52 Chapter 5s Geological History 54 Chapter 6: Mineral Deposits ......... 58 Introduction. .........«....•.•••• • 58 Production •••• •••• 58 Giltana Lake ... 59 Ihitehorse • • • • 59 {1} Geology 60 (2} Mineralogy ....» 60 (3) Origin 61 ISheaton-Windy Arm ...... • (1) introduction • ... (2) Gold-Silver quartz veins . (S) Silver-Antimony quartz veins (4) Silver-Lead quartz veins • (5) Contact Metaraorphic A t l i n District ............... ... (1) Quartz veins ..... {z\ Silver Lead veins •. ... (3) Copper veins .. (4) Antimony veins ....... < (5) Contact Met amorphic deposits Talni Area ••.••••••...•••<•..• •«• (1) Introduction . (2) Classification • • (3) Metasomatism • (4},Occurrence ••.••..*•... (5) Origin . . . . . . . . . . . . . . . . . Stild.ne-IslB.it Area • •••••...«>..• ...... (1) General Considerations ...... {2} General description ......... Unuk Area .......... . Portland Canal •.«.. •••< (1) Introduction . . . . . . . . . . . . . . . (2} General Geology • •... (3) Classification *•... (V) (4) Molybdenum Deposits ....... . Page 83 (5) Gold Pyrrhotite Deposits 84 (6) Copper Deposits • • ........ 84 (7) Quartz veins containing one or more of the 87 metals gold, s i l v e r , lead, zinc or copper (8) Sphalerite Deposits .. 95 (9) Quartz veins containing s i l v e r , lead and zinc .... 96 (10) Silver-Sarite-Jasper Deposits 97 Alice Arm-Skeena River « . .. 99 Zymoetz River Area <>•... 101 (a) General Considerations .......*...» ......... 101 (b) Mineral Zones • 101 (o) Inner Zone 101 (d) Second Zone e • »••• 103 Hazelton « 105 (a) General Considerations » . • < > • « • • • • • 105 (b) Silver Lead Deposits 106 (c) Copper Gold Deposits •«••.• 106 Hudson Bay Mountain 108 (a) General Considerations 108 (b) Occurrences • • . . . . . . . . . . • • . . . • . • • o . . 109 (c) Fissure System • ... 109 (d) Wall Rock Alteration .. • ..... 110 (e) Zoning « .......».« • 110 (f) Mineralisation. o I l l (g) Duthie H I ( ¥ 1 1 Skeena River-Eutsuk Lake • Page 112 (a) General Considerations ..................»••.••• 112 (b) Occurrences .. ...«•••• 113 Bella Coo la-Gun Creek . . « • 11$ (a) General • • • • • . . . . • • • • • • 116 (b) North of Tatla Lake 117 (c) South of Tat la Lake 118 (d) Feeny • » 118 {e) Bridge Island . ..... ...... 118 (f) Taylor Windfall . 119 (g) Taseko Motherlode ..*.*.•••••••• 120 (h) Gold Quartz Veins 9 . - 120 (i) Copper Deposits • 121 Bridge River Area • •••.<>•••..•. 122 (a) General Considerations ••• • •• •••• 122 (b) Geology 124 (0) Classification • 126 (d) Gold Quartz Veins • .... 126 (e) Country Hock •..••..•«••••••...•.•..•.• 126 (f) Wall Rock Alteration « 127 (g) Mineralization • « .•..••»..••••«.•• 128 (h) Vein Characteristics • 129 (1) Origin 130 (jl Antimony Deposits «... 131 (k) Intermediate Type «... i-^s ( ¥ 1 1 ) p ember ton Area • Page 133 (a) General Considerations «.....*•••• • •••• 133 (b) Description of Deposits « • 134 pemberton to Hope • • »«*• 136 (a) General Considerations ... •«•••• ••••• 136 (b) Quartz Veins 136 (c) Hickel Deposits .. 137 (d) Geology • 137 (e) Ore Bodies • . . 138 (f) Origin ... 138 Chapter ¥11. Summary and Conclusions , Topography ••.••••••••....••.«......••••.«« 140 Geo logy •••• 141 Mineral Deposits • -(a) General Discussion * (b) Source of Minerals •.. .... (c) Suitable Conditions for Precipitation (d) Suitable Loci of Deposition (e) Conclusion LIST OF ILLUSTRATIONS Figure 1 Key Map Page 1 Figure 2 Geological Map In pocket Figure 3 Portland Canal Area In pocket Figure 4 Zymoetz-River Area In pocket Figure 5 Bridge River Area Page 122 146 CHAPTER 1: BiTRODUOTION 1® Introd-g c t i one The immense size of the Coast Range of B r i t i s h Columbia, which is topographically and geologically a i init , has for a long time created a great deal of interest regarding its It is also this immensity which causes the total amount of knowledge of this area to appear inadequate when an attempt is made to discuss the area as a uni t® Nevertheless an attempt is made here to compile the information regarding the eastern contact of the Coast Range batholith, which constitutes the greater part of the Coast Range* While this area has not "been completely mapped and there remains a great deal of work to he done, there has probably been more work done on this area than any other similar area in B r i t i s h Columbia because of the value of the mineral deposits which are found at and adjacent to the contacts 2o Area and A c c e s s i b i l i t y » The area under discussion extends along the eastern flank of the Coast Range Mountains. It is of great length as compared with i t s width. It extends from just north of the 4 9 ° north latitude to about north latitude 6 1 ° 3 0 s in a north northwest direct ion, approximately 1100 m i l e s « The width of the Coast Range batholith in some places i s as much as 100 miles, but the width of the contact area, with i t s associated s a t e l l i t i c bodies is generally less than 15 miles. To the casual observer i t might appear that the eastern contact of the Coast Range batholith is securely hidden behind the high Coast Range, A closer examination wi l l show that this is not the case* Numerous rivers r i s ing in the interior of the province pass direct ly through the Coast Range and empty into long narrow fiords which are extensions of the numerous coastal channels* Towards the north the area is less accessible because the coast l ine swings away from the l i n e of the Coast Range mountains and there are intervening high ranges which are hindrances to easy transportation. In the northern section, transportation is mainly by boat on river and lake or by t ra in , the contact being crossed i n a north-south direct ion by the l ine of the White Pass and Yukon Railway between Skagway and Whitehorse. The contact is also crossed by the northern l ine of the Canadian national Railway from Prince Rupert and by the l ine of the Paci f ic Great Eastern Railway* The main lines of both the Canadian National and the Canadian Paci f ic Railways skirt the margin of the area in the sou th. Locally the transportation problem often presents serious d i f f i cu l t ie s chiefly because of the great r e l i e f of the country characteristic of the eastern flank of the Coast Range. S„ Climate In considering the climate of any loca l i ty i n this area the latitude must be considered, because of the length of the area* the average annual temperature varying from about 2 6 ° in the northern part, to about 4 9 ° i n the southern p a r t » Although the area is not far from the Pacif ic Ocean, the moderating influence of that body of water is very much diminished by the mass of the Coast Range, which i n most places intervenes* The variation in monthly temperature is more noticeable in the north because there the area is even farther removed from the ocean. In the north, the average temperature for January is about - 1 0 ° with a July temperature of about 5 6 ° . The difference in the south is less, the range being from about 28° in January to 64 ° in July* - 3 -The Y/esterlies prevai l ing in this region lose most of their moisture on the western slope of the Coast Range and generally speaking the area along the eastern contact is part of the transition zone between, the wet coastal area arid the comparatively dry inter ior . The bulk of the precipitation is rain but in the higher altitudes and part icular ly in the north, snow is also abundant» Locally at the end of large fiords the precipitation may be very heavy because the moisture laden winds can pass uninterrupted from the ocean to the inter ior . The average precipitation, not including the areas which are unsheltered, varies from about 15 inches pel* year in the north to about 40 inches in the sou th, 4« Agriculture» Generally speaking, the area is one of high r e l i e f and is not well adapted for cult ivat ion on a large scale. The l i t t l e farming that there is , is restricted to some of the larger valleys* Another reason why agriculture has not become more important is the lack of loca l markets for the produce. The area is very sparsely populated and there are large parts of i t , part icular ly i n the north, in which there l ive only a few trappers. Agriculture i n the past has not been an important industry and i t is unlikely that i t w i l l become more important for a long time. 5. F ie ld Work, Most of the material used in the compilation of this report has been abstracted from reports of officers of the Geological Survey. During the past two f i e l d seasons, part of the time as a student assistant on parties of the Geological Survey, I have had an opportunity to see and verify in the f i e l d , relationships of various rock masses, presumably satfrel'ites of the Coast Range batholith along its eastern contact, in southern Yukon, in the Bridge River area and in the south near C ho ate, B. C o Some of the material was found in numerous other publications which are l i s ted in the b i b l i o g r a p h y » &c Acknowledprements. I wish to express my thanks to Dr. S o J . Scho f ie ld for his interest and for his time and advice, which he gave freely. I also wish to thank Dr. W. E» Cockfield and Dr. E . J. Lees, under whom I worked for the Geological Survey, and who were always helpful* At this time I also thank those writers whose works I have used and which are l i s t ed i n the b ib l iography© -b-CHAPTBR 2t PHYSIOGRAPHY l o Relation of Contact to topography. The geological contact between the Coast Range batholith and the rocks that l i e to i t s east i s , along a good portion of i ts length, coincident with the contact between the Coast Range Mountains and the Interior Plateaux on the east. '.There the two contacts do not coincide the topographic contact generally i s to the east of the geological one, so that the geological contact along part of i t s length passes through mountainous country» 2« Coast Range. The Coast Range area, which was f i r s t elevated in the Mesozoic, 1 then relevated twice in the Tertiary, is today a high range of mountains which extends from the northern end of Burrard Inlet in southern Br i t i sh Columbia to Eluane Lake i n the southern part of the Yukon at latitude 6 1 ° . It. is close to 1100 miles long and reaches a maximum width of 100 miles© It is a remarkably straight range, s t r ik ing north-northwest and over the greater part of i t s length i t is a coastal rangeo Beyond the end of Lynn Canal, the coast l ine changes i t s s tr ike to northwest and f inal ly west and there are other ranges intervening between the Coast Range and the c o a s t « For the most part the maximum elevations along the crest of the range are 8 0 0 0 - 1 0 , 0 0 0 feet, and the peaks are concordant over large areas • In southern Brit ish Columbia some of the highest peaks are about 1 5 , 0 0 0 feet in elevation* In the north, the maximum elevation decreases gradually to 6 0 0 0 - 7 0 0 0 feet and f ina l ly the range merges into the Yukon (1) Schofield, S. J o Private Manuscript Plateaus. The mountains in the range, which is composed mostly of granitic rocks, are characterist ical ly erratic and irregular in form and possess l i t t l e symmetry* Glaciation has heen very intensive and striat ions, roches^-moutonees, U-shaped valleys, truncated spurs, cirques, through valleys and hanging valleys are common features of this coast range* The reason for the superior elevation of the Coast Range in relation to the Interior Plateau is not always evident. It is thought that the greater resistance of the massive rocks i n the Coast Range would accentuate any difference between the coast and the interior i n elevation. Further, i t is believed that the movement during the last up l i f t was d i f ferent ia l * , the greatest elevation being along the coast and the least i n the inter ior . 2 In a few instances, there is a transit ion belt between the mountainous region of the coast and the plateaux of the inter ior* Generally, the change from mountains to plateaux is abrupt, except in Yukon, where the mountains gradually merge with the plateaux. S« Interior Plateaux* The series of interior plateaux, extends continuously, with the exception of a few minor mountain ranges in northern Br i t i sh Columbia, from south of the International Boundary through B r i t i s h Columbia, Yukon and Alaska, para l le l to the coast l i n e . In southern and central B r i t i s h Columbia, the plateaux are very (1) Spencer, A . C* B u l l . G.S.Ao V o l . 14 p. 131 1903 (2) Dolmage, V. SR 1925 Pt . A p. 156 characteristics, their flatness being enhanced by their covering of nearly horizontal late Tertiary lava flows. The streams and rivers have eroded very deep canyons with vert ica l walls, sometimes over a 1000 feet below the plateau surfaces These canyons are unnoticeable when looking across the plateaux. Further north, the plateau characteristies are less easi ly recognisedo There is no great thickness of lava flows to add to the plateau effect, and the best guide as to the nature of the topography is the remarkable concordance in elevation of the peaks and r i d g e s ® Here in northern Br i t i sh Columbia and southern Yukon, great valleys have been carved out of the plateau surface so that the effect, at f i r s t glance, is that of a mountainous region. However, the concordance of peaks and the fact that the plateau surface bears no re la t ion to the geological formations are proof that this rea l ly is a plateau, which had been an uplifted peneplain, which is now being rapidly erodede. 4« Drainage. Precipitat ion on the eastern slope of the mountains i s removed by streams flowing eastward. That i s , they flow eastward for a distance and then a good proportion of them turn abruptly and jo in master rivers which flow westward through the Coast Range in deep valleys caused by antecedent rivers eroding while the Coast Range was being relevated. Those which flow eastward for a longer distance join rivers flowing more nearly para l le l to the coast, and which in turn cut through the Coast Range as the Fraser does, or encircle i t as the Yukon does* 7ab/e of . For/nat/oas ' <\ Per/orf Yi/Aon- At/z/i l^Au ft. - /sAaf -ft. . tekaf ft. - -ZymoeZ-z ft Zy/noefeft- Oi//? CA ' Go/? £/-aser ftf. c -E <V Z 0 - / c M £ 5 0 z 0 / C decent • p/e/s/ocer?e rtrevj rria/rf/e of y/vc'&/ & ./ yw*/ -y/<7C/#/ ae^Oi//* srtc'vd •y<"7c/j, 6sc-/</er c/#ys;- J,/Ar sot •5. os?t/ /?/??*> p>e a/. P/io'cs/?e Socene Aa</ ye/comes - A'tvey w/c<7#'cs-ar</estA; a#</ - &«s<r//. Sei'/me/rfji wiffi >V»V yo/ca/rtcs jr&SH/s/evP 6oSa/f, /ftf/e casif/o/nerir/* rAys/rfc ACfc//C ' //7f/~VS/fr?S &S7*/ extft/s/ves s/ofe, //fflr/r, JW- CoA/tyirfer So/iaste/?? • ~ T ~ — _. - , coo/ s^"^rs SAee/tv form**** er^////c C , / 1 = j vrf'tfrfrs • ^ T f - 1 ^ 1 /?e/7j>e> J /n//~i/n'/l/\s s?4/Jhr/?/'. ~//-~ xez/troiJe ^ ", Wrest res ^ a A j J e»»f/~*m/f tyjrr . ~ ,, , ioterf* se/As £>recc/?s l/ekw/cs 1 , J /mes/e/TP ^^/f- I ve/evyr/cs same ' c#/ij>/A/n&~o/et 1 /nfwrt^ #rj,/f'fp Sj-ra/s teze/fer, f^ywat&t  ,/"?'„S° J \-?&<?j?/afrte,r<r/e, sasTifffofre, /ifrfpifatr f/atYS aiy///,?e ft-frs 7?-/ass/c *,// SP) I /faiwj am/ 1 | t^y« /{• ser/e* . 1 ye/c<r/l/CJ OS?"' j t?rff-//>-fe t»-ecc/<?5 s* wa//o(/er jretas/Me, j/><r/& ///7?es/ti#e, ^<?/7t/sA;/7p Se/yf/?///?^ S A A £ O Z. o / c /term/as? 1 / f^y wo<Ar~J '/?/ is /./sveffM? cfiitftf. <?/~Q////e, _ , SWz/ll'O'Te, ///77P- S(V/ej <tf/ss/ss //Jp /osi Ort^nf/ c/a/7 Cc*v&r/e/i u i? •>,/•/(>} •"?</ <VWSr' mefvw&rfAosfc/ scv/i/np/its Ssr/7/s/s G/7<f jt/ip/sses-, same /X or£Se an* ve/cw/rs. cAe'r's .?i-y////fs ir/?a CD•/•/•onarrays st-tr/s/s <"'Vfi c f> M 8 e X A N ( /rrar &/& „8-OHAPTER 3 ; GENERAL GEOLOGY lo Introduction, In this chapter the rocks, of the area under discussion, w i l l be described i n a progressive order from oldest to youngest* Also, the detailed description of the rocks of any period w i l l be progressive from north to south* For convenience in treatment, the area along the contact has been divided into 5 sections, which starting in the north are: 1* the Yukon-Atlin, 2. the Taku-Iskut River, 3. the Iskut-Zyraoetz River, 4. the Zymoetz-Gun Greek, and 5. the Gun Creek-Fraser River sections. These subdivisions were chosen because it was found after an examination of reports that the geology within each of these sections was, in general, the work of two or three men, thereby making correlations of areas within these sections more certain, because each man had examined more than one area within the section. The geologists of the G. S» C. chiefly responsible for the reports concerning these sections are: 1. McConnell, R. G; Cairnes, D. D . : and Cockfield, W« E.s 2. Kerr, F . A. 3. Leach, 'V. W.;. Schofield, S. J . : Hanson, G. j 4. Dawson, G» M . ; Brock, R. W.; Marshall, J . R. j Do Image, ?.: 5 e Bowen, ET. L . ; Cams e l l , C« ; McCann, 7/. S.; Caimes, C. E . The general relationships of the rocks w i l l be discussed in another chapter, so these w i l l not be repeated. The more detailed relationships of the rocks are summarized i n this chapter by the table of formations.. 2. Pre~Cam.briana (a) Yukon-Atlin Distribution: Under the name 'Yukon Group' are included a large -9-number of different types of rocks which are found in southern Yukon and A t l i n . The masses of these rocks are scattered irregularly, and often they occur as large roof pendants in the batholith near the contact. The group includes the Mt. Stevens Group as described by Cairnes* and by 2 Cockfi eld. Lithology: Most of the types found elsewhere are a l l found in the fflieaton River area and are described by Caimes as consisting of ser ic i te and chlorite schists, mashed basic volcanics, schistose and gneissoid quartzites, hornblende gneisses and limestone. Rocks of similar type are 3 described by Cockfield from the Hiitehorse area, who attributes the great variations to different origins. In his opinion the hornblende gneisses have been formed from gabbros and granodiorites, the chlorite schists and greenstone schists from basic material, probably flows, the ser ic i te schist from rhyo1ite-breccia and the remaining types from sandstone and limestone. In the Aishihik Lake region, granite gneiss is one of the most 4 abundant types. Cockfield describes i t as a "greyish to pinkish rock with a characteristic gneissoid texture and in many cases with the development of phenocrysts, forming an augen gneiss. The mica is usually arranged in para l le l l ine s . " Origins The great variation in the types of rocks, recognized as (1) Cairn.es, D. 5. Mem 31, 1912* G.S.C. & Mem. 37, 1913. G . S . C (2) Cockfield, W.E. and B e l l , A .H . Mem. 150, 1926. G.S.C. (3) Cockfield, W. E . Mem. 150-1926. pp 8-9. (4) SR Pt .A . 1926. p . 5 -10-belonging to one group, indicates widely different modes of or ig in . At the present time they are schists or gneisses for the most part, but they are the met amorphic equivalents of elastics such as sandstone, chemical precipitates such as limestone, flows, breccias and coarse-grained plutoolcs. The limited amount of work done on these rocks i n this area i s not sufficient to permit of a narrower c lass i f icat ion but i t is evident from the rock types that they represent a great time interva l . In a l l probability there was a sinking geosynciine which was being f i l l e d continuously and then a period of intrusion preceded or accompanied or followed by surface flows and other volcanic act iv i ty* Age and Correlations Ko fossils have been found yet in any of the formations included in the Yukon Croup and so there is no direct evidence as to i t s age, They do, however, appear to be the oldest rocks i n the 1 north. Cairnes found a series of schistose rocks of pre-Middle Cambrian age along the International Boundary, and he considered that the Mt« Stevens group probably was equivalent. This tentative correlation considered along with the basal nature of the group and of their meta-morphic condition makes i t appear very probable that the group is pre-Cambrian, but there is also a very good poss ib i l i ty that some members of the group extend up into the lower Palaeozoic. 5. Devonian?—Gold Series (a) Yukon-Atlin. Distributions This series occurs as small isolated bodies. They are 1* Cairnes, D. D» Mem. 67, 1914« pp. 40-44 -11— minor in size and importance and confined to northern Br i t i sh Columbia and southern Yukon, though may be found to be more widespread after more work has been done. Lithology: Pyroxenite, peridotite and related rocks are generally placed i n this group. Sometimes veins of serpentine are associated with the masses and occasionally coarse crysta l l ine amphibole. Talc and magnesite are often found with the serpentine and sometimes the central part of the veins is chrysotile a s b e s t o s © X Cockfi eld says that the rock i s massive, i n some cases coarse grained granular and in others dense. It is generally grey to black, often with a greenish tinge and the weathered surface i s usually reddish brown due to i ron oxide coating. Microscopically, some sections were seen to contain up to 95 per cent o l iv ine , and chromite is a common accessory, usually up to about 2 per cent of the rock. Another primary mineral, unidentified, but which was probably an orthorhombic pyroxene, makes up abovj.t 20 per cent. Magnetite also occurs. Alteration products are serpentine, talc and magnesite© Origins Generally the contacts of these rocks are unexposed and i t is uncertain whether they are intrusives or extrusives and i t is quite possible that there are some of both types present© 2 Age and Correlations Cairnes found them cutting rocks of the Yukon group but that is the only direct evidence there is as to their relative posit ion in the table of formations. He says, "No other definite 1. Cockfi eld, E . Mem. 150, 1926. pp 10-11 2. Cairnes, D. D« SH 1915. p 41 information was obtained in the d i s t r i c t concerning the age of these rocks, but from their l i thologic s imilar i ty to rocks in other parts of . the Yukon and in northern B r i t i s h Columbia they are thought to be probably of about Devonian Age." 4. Devonian? Taku Groupc (a) Yukon-Atlin Distribution: Another group of rocks, confined as far as i s known to the northern part of this area is the Taku group, This group of rocks i s represented by small areas i n the v ic in i ty of Taku arm of A t l i n Lake and near Tagish Lake, lithologys This group consists of a series of cherts, slates and chertj? quartzites. Cockfi eld* describes the cherty quartzites as being found in thin beds which are generally l ight coloured. He says that the slates also are f inely bedded, and possess a slaty cleavage, and in some cases are very much folded and disturbed. The cherts vary from l ight and dark grey to black, except when weathered, i n which case they are reddish* Origin: The quartzites and slates probably are the simple meta~ morphic equivalents of ordinary water-lain sandstone and mud but the 2 origin of the cherts is less certain, Cairnes i s of the opinion that most of the chert is a s i l i c i f i e d sediment because of its intimate association with the slates and because he believes that i t s chemical 3 composition indicates th i s . Previous to Cairnes' work, Gwillim classed lo Cockfield, n . 3. Mem. 150 p / 11 2, Cairnes, D. D. Mem. 37 pp. 52-53 3o Gwillim, J. C. Geol. Surv. of Can. v o l . X l l pt B p . 17 (1699) -13-sirailar rocks as pyroclastics, being acid tuffs compacted by secondary s i l i c a , called h a l l e f l i n t a » Age and Correlations The age of this group, which is based on their l i thologica l s imi lar i ty to rocks referred to the Lower Cache Series and to their position underlying Carboniferous limestone, is at best indef-i n i t e . They have been classed as Devonian, but certainly as far as the evidence goes they might well be somewhat older or younger than that period, 5, Upper Palaeozoic, (a) Yukon-Atlin, . Distributions There is a large mass of rocks of this age extending from A t l i n Lake to Tagish and L i t t l e A t l i n Lakes. Elsewhere in this section there are only small isolated masses of these rocks and they are uncertainly c o r r e l a t e d « Lithologys Pract ica l ly the only representative of this age i n this section is limestone. In the Whitenorse area large masses of re lat ively pure limestone are of common occurrence and in some parts form ranges of •1 h i l l sc Here they are almost always pure carbonate and coarsely crystal-l ine but some beds are s l ightly argillaceous and these are fine-grained and cryptocrystalline, They are generally l ight grey in colour but vary from white to blue grey. In the A t l i n area the limestone series, which is over 3000 feet thick is similar except at the base there are occasional layers composed largely of cherty material. Age: The fossiliferous content of these limestones is scant and 3 fragmentarye Specimens of Fusulina were collected by 0. M. Dawson from the limestone on Windy Arm, indicating a Carboniferous age. Other fossi ls have been found which indicate for part a Devonian age and for part a 1« Cockfield, w. E , Mem. 150 pp 12* 2. Cairnes, D. D. Mem 37 p 53 3* Dawson, G-. M. V o l . I l l pt B. 1887-88 pp. 100-171 Triassic agSj although none of the evidence was real ly good because the fossils were not suff iciently well preserved to permit of a generic 1 determination^ Cockfield has summed up the evidence by saying that, " o . o . the various limestones have been included in one colour on the map, and have been referred to the Carboniferous, although i t is recognized that both Devonian and Triass ic may be includedo" (b) ffaka^Iskat River. Distribution and lithologys In the area between. Telegraph Creek and 2 At l in there occurs a thick series of rocks, divided by Cockfield into three divisions* The lowest consists of cherty quartzite^ slate,schist and limestone. The schist is minor in amount. There is also some altered volcanic material interbedded with these sediments. Crystalline limestone occurs over a considerable area and is classed as the second member. It i s grey or slate-coloured and pract ical ly a l l trace of the original bedding has been destroyed. Greenstones constitute the third member along with small bodies of quartzite and limestone. The greenstones are now highly altered and consist of serpentine, magnesite and chlorite but i t is probable that they a l l are derived from basic or semi-basic intrusives. 3 In discussing the Stikine Area Kerr describes the pre-permian rocks as follows. "The pre-permian rocks are found throughout the area i n more or less discontinuous masses. Generally they occur at the contact of the batholith and l i e between i t and the Permian limestone or the Mesozoic volcanics. They are in the main metamorphised sediments. Dark grey is lo Cockfield, W. E« Mem 150. p . 14 2. Cockfield, w» 3, S.R. 1925 p . 27 3o Kerr, P. A . S.R. 1928. P t . A* pp. 18-19 -15-the predominating colour, although green is also f a i r l y prevalent. In general, schists, slates and quartzites predominate, with lesser quantities of .calcareous material and v o l c a n i c s » In many places the true character of the rocks cannot he so easily indicated since metamorphism, deformation and intermingling of intrusives have created heterogeneous complexes which are not readily deciphered," Further south while referring to the same group Kerr* has the following comments, "Original ly , largely marine sediments, which were dominantly shale and sandstone of fine texture, they are now altered at least to slates, a rg i l l i t e s and quartzites, The most intense metamorphism is as a rule found in small masses included i n some of the darker intrusive phases or ly ing along their edges, In these positions complete gradations from altered, but unmistakable, sediments to typical igneous rocks can be observed." Age and Correlation: Eo fossi ls have been found in the lower member 2 of the series described by Cockfield therefore i t s age is in doubt but i t has been classed by Gwillim as being Carboniferous or Devonian and i t s l i thologica l s imilar i ty to the Taku series indicates that they may be of the same age® Some of the crystal l ine limestone described by Cockfield can be traced to the A t l i n d i s t r i c t , so possibly i t is the same age as the Carboniferous limestone on Windy Lake. The greenstones, which are mos t ly intrusives, cut the limestones 1» Kerr, F . A . S. H. 1929 P t . A p . 49. 2. Cockfield, V7. E« S. E» 1925A p . 28. - 1 6 -and quartzites, so are younger and are probably late Palaeozoic or early . 1 MesozoiCe Regarding the age of the rocks in the Stikine area, l i t t l e is knowne This group consists of the oldest and most metamorphosed series in that area, and i t underlies Permian limestone, but to what extent i t i s older than Permian is not known, or whether or not there was a long erosion interval following the deposition of this group and preceding the deposition of the Permian. (c) Iskut-Zymoetz River. Along this part of the batholith not a l l the rocks have been class i f ied, even In a general way, but a l l the work that has been done shows that rocks of this age are not abundant in this s t r i p , indeed, the only rocks in this area known to be of Carboniferous age are boulders of limestone in a Triassic conglomerate on Zymoetz River. (d) Zymoetz River to Gun Creek. Distribution: Proceeding south, i t is found that there are more Carboniferous rocks in the v i c i n i t y of Eutsuk Lake, and also some old gneisses which may be of this age are found on the contact of the batholith between Tatla aid. Bella Coola. 2 Lithology: As described by Brock in the Eutsuk Lake d i s t r i c t , this group includes cherts^spotted argi l l i tes , and carbonaceous schistose rocks. The one near Tatla h i l l are gneisses which may represent a highly meta-morphosed contact of the ba tho l i th© There are two types of gneisses here, both of which are banded and their origin is uncer ta in© 1* Cockfield, We E . S. R. 1925. Pt . A . p . 28 2o Brock, R„ We S. R. 1920. P t . A* p. 86 3. Dolmage, V. S. R. 1925. P t . A . p . 158 -17-Age: Brock* did not find any fossils in the sediments near Eutsuk lake hut based his opinion on the l i thologica l s imi lar i ty of the rocks he saw to others of the Cache Creek series of Carboniferous age® In regard to the gneissic group, DoImage says, "The poss ib i l i ty that the gneissic rocks belong to a much older series of rocks than the •Triassic must not be overlooked." This statement i s based on their lithology and their relat ion to the contact, but as i t is not to be expected that fossils w i l l be found i n these rocks i t appears to be the best evidence by which to date them, (e) Qua Creek-Fraser River. Distribution: The Carboniferous rocks again become prominent members included of the group of rocks 4ffibsuded in the contact area. They are found abundantly from Gun lake to the southern end of the batholith*, 3 Lithology: In the Bridge Hiver area , they consist of metamorphosed sedimentary formations with interbedded volcanic rocks. The chief sediment is a bluish grey chert, which grades into a cherty quartzite, Thin layers of a r g i l l i t e separate the narrow bands of chert. Sandstone and limestone are also included in this series* Black altered basalt is the most common volcanic present. It grades into andesite. In places these volcanic members have been altered to chlori te and serpentine. 4 Where exposed on the Eraser River , they are black slates with some occasional limestone beds. There are also some schists which may be 1. Brock, R. W. S . R« 1920. P t . A . p . 85 2* Do Image, \ra S . R« 1925. P t . A . p* 158 3o McCann, W. So Mem. 130. p. 23 4o Bowen, N. L» S . R. 1912, p „ 109 metamorphosed basic igneous rocks a Age and Correlations Ho fossi ls were found in these rocks, either i n the Bridge River area, where they are called the Bridge River series, or on the Fraser River. On l i tho log ica l and structural evidence, they have been correlated with the Cache Creek series, which is Carboniferous* 6® Permian Distributions Permian rocks, as far as is known, are confined to that part of the area in the v i c in i ty of Taku„ Stikine and Iskut Rivers, and possibly some areas i n Atlin-southern Yukon section. Lithologys Limestone is the only rock of this period found in the area* .Kerr* describes i t as f a i r l y uniform, l ight grey, generally f a i r l y pure and crysta l l ine . In part i t is well bedded and i n part i t i s raassive« 2 Ages In regard to the age of this limestone Kerr says, "In Stikine River area fossi ls have definitely fixed the age of this series as Permian." He goes on to say that some members of the limestone, already discussed above; considered to be Carboniferous because containing the fos s i l 3 Fusulina , may well be Permian, because the Permian limestone i n the Stikine area also contains Fusulina. 7. Tr ia s s ic . (a) Yukon-Atlin. Distributions Rocks of this period are found local ly i n this area 4 but not to any great extent. The Lewes River series, which i s the name 1. Kerr, F . A . S. R. 1928 P t . A. p . 19 and S. R. 1929 Pt . A . p . 21 3o Dawson, G. M. Ann. Rep. G. S. C. V o l . I l l P t . 3. 1887-88 pp. 170-171 4» Lees, E . J . Reprint Trans: Royal Canadian Institute V o l . XX Part 1 1933 p;;' 12. -19-now proposed for a l l these rocks, is found part icularly in the v i c in i ty of lake Laberge, although also found near Whitehorse. Lithology: Limestone makes up the hulk of this series, the total thickness of which is between 2000 and 2000 feet® Volcanics and gi'eywackes also occur* The limestone is massive and generally l ight to bluish grey. Age: Numerous fossils have been found in this series and the age is considered to be upper Tr ia s s ic . (b) Taka-lskut River. Distributions Rocks believed to be of Tr iass ic age are abundant in this section, in local masses, generally separated from the contact of the batholith by Palaeozoic sedimentse 1 Lithology: They have been described by Kerr" as consisting essential-ly of volcanic material* They are green, with gray and rarely other shades® In many sections the base is marked by an explosive breccia, in others by a series of bedded calcareous tuffs• The beds are massive and most of the rocks are tuffs and fine-grained breccias. There are minor quantities of flows. A few agglomerates and conglomerates are included* They are generally green because of the abundant development of chlorite and similar m i n e r a l s « Age: Triass ic fossils have been found, which definitely indicate that the series is mostly Tr iass ic , although part of i t may be younger. It rests unconformably upon the eroded palaeozoics, and i t probably was deposited contemporaneously with other volcanics found to the south. 1. Kerr, F« A . S. R. 1928. Pt . Ac p . 20 and 3. R. 1929 pt . A« p» 51 -20-(c) Iskat-Zymoetz River. Distribution: Rocks of Triassic age appear i n this section, only in the val ley of Zymoetz River* Some of the numerous small inclusions i n the batholith may also be of this age® 1 Lithology: Hanson describes them as consisting of crystal l ine lime-stone, thin beds of cherty quartzite, a r g i l l i t e and slate* Also there are conglomerates of chert pebbles and limestone boulders* The a r g i l l i t e and cherty quartzite are often interbedded and also grade into each other© There are also some beds of breccia and tuff which may be of the same age® Age: In the a r g i l l i t e s „ Daonella sp» has been found which indicates a Triass ic age. The limestone boulders in the conglomerate contain fossils which indicate a probable Permian age, so i t is l i k e l y that the series including the conglomerates i s Triass ic* (d) Zymoetz-Gun Greek* Distribution: Triass ic rocks are quite important along this section, being found near Lakelse Lake, Chilko Lake and between Tatla and Bella Coolae In the Lakelse Lake area, they occur as roof pendants i n the batholith but i n the other areas they are abundant east of the contact of the batholith. 2 Lithology: As described by Marshall they consist mainly of lime-stone and marble along with cherty quartzite with some tuffaceous material and a r g i l l i t e . The total estimated thickness is about 1000 feet* The Triassic' rocks, northwest of West Homathko valley consist of a thick series of volcanics with which are interbedded thin beds of 1* Hanson, G. S* R. 1925 Pt . A p . 103 2. Marshall, J . R. S. R. 1926 Pt . A . p . 38 "21-1 a r g i l l i t e and lenses of limestone . The volcanics are chiefly tuffs and breccias. Some dark andesite flows are also i n the series. The wide 2 band found between Tatlayoco and Taseko Lakes consists of flows of andesite with some basalt with which are great thicknesses of rhyol i t i c and andesitic tuffs, as well as small amounts of sandstone, conglomerate, a r g i l l i t e and limestone. Age: No fossi ls were found in the Lakelse Lake area, but the rocks are pract ica l ly identical with the fossiliferous Triass ic series found in the Zymoetz valley, so that they may be correlated with some certainty. In the other two areas, described by DoImage, characteristic Triassic fossils were found which definitely date the beds, although the upper l imi t of the series in either case is not well defined** (e) Gun Creek-Fraser River® Distribution: Triass ic rocks are quite widespread i n this section, having been described from both the Bridge River and Pemberton Areas. Lithology: Serpentine rocks, which are of two varieties,, have been 5 described by McCann . One of which^the porphyri t ie, appears to have been composed of olivine-gabbro p o r p h y r i t e « They weather to a grey-brown color and are not completely altered, pyroxene crystals appearing as phenocrysts. The other serpentines are dense, and were probably derived from olivine basalts. They weather to red-browns or brown-yellow. In some cases the serpentines have now been altered to magnesite. 4 Also found in the Bridge River area is the Cadwallader series o ! • Do Image, V. S R 1925. P t . A . p . 158 H . S B 1924. P t . A. p . 64 3. McCann, V7. S. Mem. 130 p . 26 & 4. Mem. 130 p . 28 - 2 £ -It includes great thicknesses of "basaltic and andesitic greenstone, con-glomerate, sandstone and shales. There are also small amounts of limestone and dolomite. The greenstones are most abundant i n the lower part, and look quite fresh. The tota l exposed thickness is about 2100 feet. In the Pemberton area*, the Triass ic also includes volcanic and sedimentary beds. The volcanic types are chiefly fragmental types such as tuffs and breccias, while the sediments are slates and impure sandstones. There are also a few andesitic flows and some conglomerate and a few lenses of limestone. Age: As regards the age of the serpentines, HoCann says, " i t is concluded that the serpentine rocks were extruded over the erosion surface of the Bridge River series of Pennsylvanian-Permian age, before the Cadwallader series was l a i d down. The age therefore wi l l be assumed tentatively to be Tr i a s s i c . " Fossils found in the upper members of the Cadwallader series 2 indicate their age to be upper Tr ia s s i c . Do Image believes that these beds are equivalent to the group he has described which l i e s between Tatlayoco and Taseko £ a k e s . Fossi ls indicative of an upper Triassic age for some members of the series exposed in the Pemberton area were found, and so these beds can be correlated with the Cadwallader series. There is the pos s ib i l i ty that portions may extend into lower Triass ic or Jurassic because the fossils were confined to one portion of the series. 1. Cairnes, C. E . S. R. 1924. P t . A* p . 79 2. Dolmage, V. S. R. 1924. Pt . A . p . 65 -23-8* Jurassic, (a) Yukon-Atlin , Distribution; This period is well represented in this section, the greater portion of the rock exposed east of the batholith being of this age. The laberge series, the overlying Tantalus conglomerate, and the Older Volcanics being of this age* Lithologys In the Whitehorse D i s t r i c t * the series is at least 5000 feet thick and i t is quite probable that i t may be 10,000 feet thick* Volcanic elastics , tuffs, sandstone, breccias, and conglomerates predom-inate and interbedded with the tuffs are marine shales and a r g i l l i t e s . There are also thin beds of dark limestone* 2 In the Wheaton d i s t r ic t Cairnes recognized three divisions of this series* The upper 1500 feet being sandstone, the middle 1800 feet being shales, arkoses and sandstone and the lower 1800 feet being arkoses and taffs with shales and conglomerate. This conglomerate contains boulders up to three or four feet i n diameter of a similar composition as the Coast Range batholith and fragments derived from the Older Volcanics* 3 Overlying the Laberge series is the Tantalus conglomerate • It consists chiefly of massive beds of conglomerate with some sandstone, shale and coal* The conglomerate pebbles are quartz^chert or slate and are remarkably uniform in s ize, rarely exceeding 3 inches in diameter* 4 Also included here are the Older Volcanics which consist chiefly 1* Cockfield, W» E* Mem. 150, p . 15 Z. Mem. 150, p . 22 4* op. c i t p. 23 2. Cairnes, D. D* Mem. 31, pp. 54-56 -24-of andesites, diabases and basalts, There are also a few deep-seated basic rocks such as dior i te , gabbro and amphibol i te® They are generally fine-grained and often porphyrinic and now are often altered so that their original character is in doubt* Age and Correlations While fossils are not abundant in the Laberge series, enough have been found to permit Cockfield to state that, " i t appears t o be very well established that the Laberge beds range i n age from middle Lower Jurassic to lower Middle Jurassic"* It is possible that these l imits may have t o be extended because the fossils may not represent the complete series. At one place the tuffs of this series were seen to overly unconformably the Palaeozoic limestone* This series is also intruded by the Coast Range batholith. The Tantalus conglomerate overlies the Laberge series and the fossils found in i t also indicate a Jurassic age, so i t probably is Upper J u r a s s i c ® The Older Volcanics include both the Perkins group and Chieftain H i l l volcanics, which terms had been used by Cairnes. Pebbles of the Perkins group found in the Laberge beds indicates part of the Volcanics to I be older than the Laberge series. However Cockfield states that "portions of the Older Volcanics are definitely intrusive into the Laberge beds, and may, therefore be considered younger." Also the tuffs of the Older Volcanics are so similar to those of the Laberge series that i t would appear as i f they were contemporaneous. Cockfield also states that "The Older Volcanics are, probably, a l l older than the granitic intrusives". 1. Cockfield, W. E« Mem. 150, p . 29 -25-Ihe conclusion that may he drawn from this evidence is that the vulcanism responsible for the Older Volcanics stopped i n Upper Jurassic times after i t .had continued a l l through the Jurassic. The date of beginning of the vulcanism is not known* (h) Taku-Iskut River. Distributions Along this section, insufficient detailed work has been done to separate the Jurassic from the underlying Triass ic , but i t is known that there are less Jurassic rocks present than there are Tr ia s s ic . lithologys The Jurassic here, is composed pract ica l ly of volcanics, with minor amounts of conglomerate. The description given by Kerr^ i s given for the whole series which i s mostly Triassic but which includes som< Jurassic. The volcanics are flows and tuffs along with some breccias and agglomerates. In places there are also a rg i l l i t e s and quartzites, slates, schists and a small amount of limestone. The base i n many parts i s indicated by a conglomerate, which in some cases is very thick and con-tains abundant granit ic boulders© Ages Fossils indicative of a Jurassic age have been, found i n some of 2 the limestone lenses • (o) iBkut to Zymoetg River. Distributions Apart from the Coast Range intrusives, Jurassic rocks are the most abundant by far a l l through this section. They occur a l l through the Portland Canal area, between that area and the Skeena River, on the Skeena River and south of i t * 1. Kerr, F . A . 3. R. 1928, Pt . A, p . 20 & 2. S. R. 1928, P t , A» p . 20 - 2 6 -1 lithology? A recent memoir by Hanson is a compilation of several reports on the Portland Canal-Alice Arm region. In this area, the Haz.elton group i s the oldest. It consists of a great variety of igneous and sedimentary rocks. In some parts the sediments are undisturbed, but i n many there occur great masses, roughly lens- l ike , of igneous rock, both intrusive and extrusive, which are roughly conformable with the surrounding sediments. The sediments are black a r g i l l i t e s with local interbeds of greywacke and argillaceous quartzite. They gradually change into s t ra t i -fied tu f f s® In the v i c i n i t y of Al ice Arm the sediments are at least 3000 feet thick. Minor amounts of limestone, fine pebble conglomerate and micaceous schists also occur. The igneous rocks of this group in the Portland Canal area are chiefly tuffs, breccias and intrusives. The thickness of the bedded volcanic rocks probably exceeds 3000 feet. Of the intrusives, augite porphrites, augite syenites, fels ites and felspar porphyrys are most important. 2 South of the Portland Canal are*to the Skeena River , this period i s represented by massive purple and green tuffs and breccias and by wide-spread amounts of sandstone, quartzites and argillaceous quartzites. 3 Along the Skeena River , the rocks of this period are again well exposed. The lower part consisting of massive and fragmental volcanics and the sediments of a rg i l l i t e s and quartzites although near the contact the sediments are hard and cherty. 4 In the Zymoetz River area „ this period is represented by rocks 1. Hanson, G. Mem. 175 2 . S . R . 1922, Pt . A. p . 41 3 . So R . 1924, Pt .A p.40 4. So R . 1925, P t . A . pp. 104-106 described under four divisions, with a total thickness of approximately 10,000 feet. The divisions are: Upper Sedimentary Divis ion - 1000 feet -consists of a r g i l l i t e , quartzite, conglomerate and some coal seamse Upper Volcanic Divis ion - 2000-3000 feet - abundantly represented on Hudson Bay mountain. It consists chiefly of andesitic lava flows and massive beds o f coarse breccia. Middle Sedimentary Divis ion - 500 feet - i t consists of a r g i l l i t e s , quartzites and argillaceous quartzites i n thick and thin beds, lower Volcanic Division - 4500 feet - mostly andesitic in composition including flows, tuffs and breccias. Age and Correlation: Fossils have been found in the Zymoetz River area in the Middle Sedimentary Division, indicating a lower Middle Jurassic age. Fossils have also been found in the sedimentary members elsewhere which indicate that the HazeIton group may range from Triass ic 2 to Cretaceous. Hanson says , "Most of the Hazelton group as indicated by marine fossils i s of Jurassic age, but this series of rocks is of wide-spread extent and may reach upward into early Cretaceous and downward into the Tr i a s s i c . " A l l the parts of this section have been connected by reconnaisance traverses so the correlation of a l l these areas i s f a i r l y certain. The l i thologioal s imilar i ty of the rocks of the series suggests that at one time they were i n direct connection with the Jurassic rocks in the Taku-Iskut section and with Jurassic rocks to the south, (d) Zymoetz-Gian. Creek Distribution: Rocks of this age are very abundant i n the northern 1. Hanson, G-. S. R. 1925, P t . A. p . 105 2. S. R. 1924, Pt . A, p . -28-part of this s ection. They appear to have been removed by erosion i n the southern part. In the northern part they are found near Lakelse, Eutsuk and Tahtsa lakes* 1 l ithology* Near Lakelse Lake t they consist mainly of s trat i f ied red tuf f s© There are also some breccias and flows which are a l l f a i r l y ac id ic . 2 In the Eutsuk lake region. Brock describes the same series p which he calls the Porphyrit ic , as consisting of massive lavas, agglomerates, conglomerates, tuffs and ashes and a few beds of a r g i l l i t e and limestone* Most of the volcanics are andesitic and are generally somewhat altered* Brock says, "This series certainly exceeds 10,000 feet in the Eutsuk D i s t r i c t . " 3 Regarding the Eutsuk Lake area Marshall says that the series i s at least 16,000 feet thick, and that i t fa l l s into three divisions* A lower volcanic member consisting of greenstone porphyrites and some vesicular lavas. The middle sedimentary member consists of thin beds of limestone, black a r g i l l i t e s , and some waterlain tuffs, with a few inter-bedded tuffs, agglomerates and breccias. The volcanics. are mainly andesitic. Overlying this is the upper volcanic member, which i s composed mainly of fragmental rocks* These include fine and coarse tuffs, breccias and agglomerates with a few acidic flows* Similar rocks are found in the Whitesail-Tahtsa Lakes area and the members are continuous with those near Eutsuk Lake* 1* Marshall, J . R* S. R. 1926, P t « A, p . 38 2. Brock, R. W* S* R* 1920, Pt* A, p . 87 3. Marshall, JB S« R. 1925, P t . A, pp. 148-150 4« S. R. 1924, Pt . A, p.50 ~£9~ Age and Correlation. The Hazelton group exposed in the Lakelse lake area is a part of the Hazelton group of the 2ymo6tz River area and so can be-assumed to be of about the same a g e « In the other areas within this section along the contact, fossi ls which indefinitely indicate a Jurassic age have been found® Those fossils that have been found are generally imperfectly preserved, and then they often are not of specific use because of a long range. However, the fact that such fossi ls have been found and that the series as a unit bears such str iking resemblances in lithology to those areas farther no&th makes the correlation of the Hazelton i n this section with the Hazelton to the north, a matter of considerable certainty. At the present time the name Hazelton. i s used to apply to the same group of rocks that foimerly had been called the Porphyrites. This change was required by the fact that the term porphyrite which was a good 1 descriptive one i n the loca l i ty in which i t was adopted by Dawson , is not a suitable term in the sections to the north and east where sediments are 2 predominant in the series. It is of interest to note that Leach realized this progressive change i n the l ithology of this series, for he said i n regard to this series, "There seems to have been from south to north a gradual transit ion from rocks of purely volcanic or ig in (chiefly pcrphyrites) to aqueous deposits such as those near Hazelton.w (e) Gun-Fraser River. Along this section, there are no strat i f ied rocks which are considered to be of Jurassic age only. 1. Dawson, G. M. Am. Rept. 1876-77 p . 58 2. Leach, W. W. S. R. 1909, p . 63. •"30-*8» Batholithic Intrusive Rocks, (a) General It is known that not a l l the intrusions considered, as parts of the Coast Range batholith are the same age, hut i t is known that a great deal of the mass, and probably the bulk of i t , was intruded towards the end of the Jurassic. Because the batholith i s a un i t e i t is considered best to treat i t i n i t s entirety at this point rather than discuss the various phases under the periods in which they were intruded. The age of the batholith i s generally arrived at by a consider-ation of the relationship of the s a t e l l i t i c bodies. This throws some doubt possibly on the age, because the sate l l i tes may be i n some cases of a different age* Another means of arr iving at an age of the intrusives is to f ind out when the batholith was unroofed by means of boulders or pebbles of intrusive rock i n a basal conglomerate. This is useful as a means of setting an upper l imi t for the time of intrusion, (b) Pre-Si lurian In south-eastern Alaska*, conglomerate beds, interbedded with definite S i lur ian limestones are found. Some of the boulders i n the conglomerate are two feet in diameter and besides boulders of lavas and limestone there are boulders of granitic rocks. Among these are d ior i te , quartz d ior i te , monyonite and granite boulders. These granitic fragments are present i n small amounts over large areas * Their size is evidence that they could not travel far and since 1. Buddington, A. F« and Chap i n , T. Bull 800. U.S.G.S. p . 86 no pre-Silurian intrusive has been discovered i n the v i c in i ty i t is thought probable that i t is now covered by the waters of the Paci f ic * 17o period of d ias trophi sm, with which igneous intrusion on a large scale i s coincident, i s known of i n the Palaeozoic before the Si lurian, therefore the conclusion is that these granitic boulders were derived from a pre-Cambrian mass which was not far to the west of the present coast l i n e . This pre-Cambrian intrusion then was the forerunner of the batholith and lay a l i t t l e west of where the batholith is now exposed. (c) Pre-Tria8sic Instances of the occurrence of granit ic pebbles in the Triass ic 1 are known. These have been described by Jamesg Burwash and Leroy , and a l l the occurrences are on the mainland of southern Br i t i sh Columbia© In this regard James says that pebbles of granodiorite up to 3 inches i n diameter occur in a metabasalt flow* This flow occurs at the 2 base of the Britannia formation which is thought to be Triassic in age « This proves that i n southern Br i t i sh Columbia there must have been a granitic mass intruded before Triass ic times. There is no other evidence as to the age of this intrusive and i t is probable that this intrusive may also be of pre-Cambrian age* (d) Pre-Jurassic Granitic pebbles have also been found i n considerable quantities-i n Jurassic conglomerates and near Topley there is more evidence of a pre-1* James, H. T* Mem, 158, pp 10-13, Leroy, 0. E* #996, pub. G.S.C* p . 15, Burwash, E* M. J . Geology of Vancouver and Vic in i ty . University of Chicago Press 1918, P . 40* 2* James, H. T . Memoir 158, p . 13 -32-Jurassio intrusion. At Topley there is a mass of granite overlain by what are 1 thought to be Jurassic sediments • In some of the conglomerate beds of the Laberge series i n southern Yukon, granit ic boulders up to 2 feet in diameter are common and some are even larger. These boulders show considerable variation i n composition, although they are l ight coloured intrusives and they would appear to have come from a complex intrusive mass. Their size indicates that they are not far from their source* 2 Kerr states that boulders of oligoclase granodiorite are found in a Jurassic conglomerate in the Stikine area* These pebbles, he says, are very similar to masses of oligoclase granodiorite found nearby. He is of the opinion that these granodiorite boulders are close to their source and that they were derived from the oligoclase grandiorite exposed nearby and that this mass was probably intruded in Triass ic times, i n the same area there are two other types, a hornblende granodiorite and an alkal ie syenite sp^arate intrusions, both of which, being cut by the oligoclase granodiorite, he believes to be of Triassic age. This is a very much disturbed area and i t is possible that there was some diastro-phism and related i nt ru s ion, although such diastrophism could not have been widespread because i t s effects have not been noted elsewhere in the Cordi l lera . With reference to the boulders in the Laberge series, the data is similar to that i n the Stikine area inasmuch as i t sets an upper l imit on the time of intrusion and the lower l imit i s not known. It is possible 1. Hanson, G.<tf Phemister T* C. S. R. 1928* pt . A. pp. 56-59 2. Kerr, F. A. Proceedings R. s. C. 1932 v o l . SXVl -33-that here as i n the Stikine there was a Triassic intrusion* It is also possible that the boulders were derived from the pre-Cambrian intrusives, already mentioned and which may be hidden not far below the surface* The intrusion near Topley is the only one definitely known to be overlain by Jurassic strata* Here, as i n the other cases, the youngest strata which i t cuts are not known so the lever l imit can not be set© The conclusion drawn i n regard to these pre-Jurassic intrusions is that the evidence regarding their age is very incomplete and a l l of these intrusions may be referred to the pre-Cambrian, but there i s also the pos-s i b i l i t y that there were local intrusions i n Triassic timeso (e) Upper Jurassic Intrusives The greater part of the mass of the Coast Range batholith appears to have been intruded towards the close of the Jurassic period* In the northern section, these intrusives cut the Laberge series at different places proving that the intrusives are post-Middle Jurassic* The intrusives have not been observed i n contact with the overlying Tantalus conglomerate* In the Stikine area, Kerr believes that there were two or three intrusions during Jurassic times, probably towards the close* This determination i s based on their relationship to older intrusives because they do not cut s t rat i f ied rocks younger than those of the Triass ic period* l a Schofield and Hanson i n the Salmon River area found the intrusives cutting the rocks now considered part of the Hazelton group of 2 Jurassic age. Hanson also found granodiorite pebbles i n a Lower 1. Kerr, F . A* Pro. R. S* C* Vol* XXVI 1932 la * Schofield, S* J . and Hanson, G. Mem 132, p . 13 2* Hanson, G» S* R. 1924. P t . A* p . 41 Cretaceous conglomerate of the Skeena formation which is generally less complexly folded than the underlying Hazelton group ard which sometimes has a- f a i r ly thick basal conglomerate* Furthermore the Skeena formation has not been seen to hare been cut by the intrusives* Proceeding south, the intrusives are found cutting the Hazelton group, or what was formerly the Porphyrite group* This sets the lower l imit of the intrusives as being post-Middle Jurassic* Near the southern end of the batholith, the augLte diori te stocks i n the Bridge River area cut the Upper Triassic Cadwallader Creek series and are 1 believed to be Upper Jurassic in age • There appears to be ample evidence to justify the conclusion that a great deal of the intrusion of the batholith took place towards the close of Jurassic times, when the overlying Jurassic beds were folded and then the Lower Cretaceous sediments l a i d down unconformably on their eroded surfaces* (f) post-basal Lower Cretaceous There is probably more evidence regarding a later age for some of the intrusions of the batholith, along the eastern margin, than either the central or western portions* 2a Kerr distinguishes 3 phases i n the Stikine which he believes are Lower Cretaceous because they cut Jurassic intrusions* 2 Between Tatla and Bella Cooia, and near Chilko Lake9 Dolmage has found the batholith and i t s satel l i tes cutting Lower Cretaceous strata* 3 Also in the Gun Creek area he found the batholithic rocks intruding 1. McCann, W. So Mem. 130 p. 32 p . 85 2* Dommage, V . S. R. 1925. p* 161 and S R 1924, p . 67 & 3* SB 1928, pt . A 2a. Kerr, F . A* Proceed. Ro S. C. V o l . XXVl-1932 -35-Lower Cretaceous beds which had previously been folded into a perpendicular posture. He says further that, " i t can be very def inite ly stated that a very large part of the batholith is post-Lower Cretaceous.*1 In this same area there is a younger phase cutting this one* 1 In the Bridge Eiver area the Bendor body cuts lower Cretaceous strata* In the southern extremity near Harrison Lake and the Fraser 2 r iver the intrusive, which forms the eastern part of the batholith at any rate, appears to be the same as an intrusive found by Cairnes in the Coquihalla to be Cretaceous in age. The upper l imi t of these intrusions is not definitely known, nor is i t known i f they are a l l of the same age. In some cases they are not seen i n contact with younger rocks and i n other cases the overlying rocks 4 are of undetermined Tertiary age. Schofield believes that a l l these later intrusions are of the same age, which i s quite l ike ly , and that that age is post-Upper Cretaceous. This is probable because that was the time of the Laramide revolution. It is possible that some of the masses within the batholith are either Gligocene or post-Miocene i n age being contemporaneous with intrusions of these ages outside this map area. A gabbro of Oligocene age occurs on Vancouver Island while the Snoqualmie post-Miocene granodiorite is found in the State of Washington. 1. McCann, W. S. Mem. 130, p. 38 2. (Jummings, J . M. Personal Communication 3. Cairnes, C. IS. Mem. 139, p . 97 4. Schofield, S. J . Private Manuscript. -36-[s) Lithology At one time i t was considered that the batholith was a mass of rock which had been intruded along i t s length a l l at one time* This was an early opinion when l i t t l e field work had been done* It Is now known that i t is composite in age and l i thology. The number of different phases found i n the batholith is un-known; i n some areas many different types being recognizable; while i n others the rock is homogeneous over large areas© An examination of the l i terature pertaining to the eastern contact shows that granodiorite i s the most common rock. The next most common types in order of importance arej quartz d ior i te , d ior i te and granite wi th syenite and inonzonite recorded also. There are also small amounts of gabbros. Granodiorite, found, in each of 24 areas consulted, is the most common type. This does not mean that 24 different granodiorites have been recognized but that granodiorite is continuous throughout the area mapped© This granodiorite consists essentially of quartz, plagioclase, orthoclase or microciine, hornblende and b io t i t e . Common accessories are magnetite, apatite, zircon and sphene. The plagioclase ranges from oligoclase to andesine. The amount of orthoclase or microciine often showing the greatest variation. In many cases this type tends towards being a quartz monzonite or a quartz d ior i t e . Quartz d ior i te , the second most abundant type was found i n nine of the areas considered. In connection with this i t may be noted that with the exception of an occurrence i n the Stikine a l l these occurrences are south of Portland Canal. Mineralogically i t is similar to the grandiorite, the principal difference being due to the small proportion of orthoclase. -37-Another difference i s that the plagioclase i s sometimes andesine-labra-dorite* Dior i te 9 the th i rd most abundant type, while found in 6 areas i s less important than the other tro because the occurrences are relative-l y small* Locally i t may be of great economic importance either as a source or host for metalliferous solutions. An instance of the former is the diori te on the property of the B. C* Nickel Company near Choate, and an instance of the latter, the diorite in the Bridge River area which is the host rock for the gold quartz veins* Augite or some other pyroxene is quite a common constituent of these diori tes . It was also noted that this type of rock is more abundant i n the southern part of the batholith* In regard to the other types mentioned above, i t may be said that they do not differ a great deal from those already descr ibed© Ho marked arrangement i n their distr ibution was noted, possibly because they are so few® 1 Considering the batholith as a uni t , Schofield has come to the conclusion that the greater part of i t consists o f granodiorite and that the margin consists to a great extent of quartz d ior i te * In applying this generalization to the eastern contact i t i s found that in part, the basic periphery is present, in part i t is absent and i n part the data i s not available* £* Burwash , when speaking of the southern part of the batholith says, "This marginal differentiati on generally takes the form of a decrease in quartz and an increase in hornblende*" 3 Further, Buddington in speaking of southeastern Alaska states 1. Schofield, S* J . 1932. Personal Manuscript. 2* Burwash, E.M.J . Geology of Vancouver and v i c i n i t y , p . 50, Univ. Chicago press-1918 3* Buddington, A. F* U . 5 » G * S . B u l l . 800, p . 237. that, "She evidence where the relations have teen studied is positive i n indicating that quartz diorite is in many places a marginal border variant to more a lka l ic types such as granodiorite*." The granodiorite and the quartz dior i te often merge into each other hut in other places their contacts are sharp and well defined* These differences in. contacts are best explained by a two fold 1 theory » F i r s t a batholith is intruded and i t s surface crystal l izes and a basic margin forms while differentiation proceeds within the molten i n -ter ior . At a later epooh during the. same period of revolution the magma may r ise again to relieve the accumulated stress and break through the basic margin causing a more or less sharp contact with i t . In the f i r s t case the change from the basic margin to the more acidic exterior would be gradual but in the second case the change would be sharp© Variations tending towards more basic types found in the section 2 between Bella Coola and Tatla would appear to be due to assimilation of the country rock because the variat ion i s noticeable at the main contact and also at the contact of the intrusives with roof pendants. At one place along this section there is a band of hornblende diori te along the contact which extends inward between one-half to three-quarters of a mile before changing to l ight grey quartz d ior i te * In the central portion of the area i n the v i c in i ty of the Fort-land Canal and Stikine River where possibly better opportunities for exam-ining cross-sections of the batholith than elsewhere are obtainable, 3 Buddington believes that there is a tendency,, notwithstanding the basic 1* Bancroft, J . A . Mem. 23, p . 104, 1913 2. Dolmage, V . S. R. 1925, Pt* A, p . 160 3. Buddington, A. F . B u l l . 800, 1925* U* S. G. S« p . 181 -39=' marginB for the "batholith rooks to become s l i ght ly more acidic from west to east. He gives as a general d iv i s ion of the batholith, a western quartz dior i te belt, a central granodiorite belt, and an eastern quartz monzonite belt, which by his usage contains more potassic felspar than does the granodiorite. However, he states that the change is by no means gradual and he does not offer an explanation as to the change. 1 Do Image however, in describing the area south o f this states that, "These more acid types show a general tendency to l i e toward the central part of the batholith, but there are exceptions to th i s . " This is an agreement, more or less, with schofield's idea of a basic margin. Contrasting somewhat with these opinions, is the one held by 2 Kerr . He finds that along the eastern contact, i n and around the valley of the Stikine that the greater portion of the batholith is granodiorite but i t is not a l l one mass and some of i t is close to the core and some of i t near the margin. Also he does not recognize any orderly arrangement to the rest of the phases present© In this area he f i n d B 9 dist inctive intrusives which is considerably more than has been found anywhere else along the contact so that i t is possible that this i s a special area within which unusual conditions controlled the intrusions. If such i s the case, and i t seems l i k e l y , then this area should not be discussed along with the rest of the batholith, and the findings i n regard to this area should be disregarded when considering the batholith as a uni t . In conclusion, i t may be said, 1. that the major portion of the batholith is composed of granodiorite; 2. that in places the batholith becomes more basic toward i t s margin, either because of assimi-1. DoImage, V. S. B> 1922, Pt . A, p . 16 2. Kerr, F . A. Proceed. R. S. C. 1932 -40-la t ion or differentiation, and 3» that the eastern contact rocks may he s l ight ly more acid than those of the western contact© (h) Attitude of Contact, Where the dip of the contact of a batholith can not be seen i n a natural section across the contact, the dip may be inferred from surface observations. If the contact is exposed i n a very irregular fashion, with numerous projections out from the main batholith, then i t i s assumed that the dip i s low because a section across the contact and only at a small angle with i t w i l l emphasize minor irregulari t ies on the batholith'e sur face© Numerous roof pendants are also indicative of a contact that makes only a low angle with the present plane of erosion* A wide meta-llic rp hie zone is also a good indication of a greatly dipping contacts The lack of these conditions indicates a steeply dipping contact or one which is cut by the present erosion plane at a large angle. Therefore, a smooth regular contact, without numerous roof pendants and a wide met amorphic zone are a l l good indications that the contact is dipping steeply. Using the above cr i ter ia and also considering the temperature of deposition of ore deposits along the eastern contact, Schofield has come to the conclusion that the dip of the contact of the batholith with the intruded rocks is steep, and that erosion has removed most of the roof rocks from along that contact. This is true along a good portion of the contact but there are numerous places where the c r i t e r i a indicate that the dip of the contact is low. In the Aishihik Lake region, Cockfi eld" says that, " . . . . t h e eastern margin of the batholith i n this region slopes gently eastward with 1. Schofield, S. J . Memoir 132. pp 64-65 2. Cockfield, W. E . s. R. 1926, P t . A. p. 10 recurrent upward projections whose summits have been l a i d bare to the east of the main margin.," In this case, this shallow dip may be due to the batholith plunging underneath the overlying rocks because this is the northern extremity of the batholith. Between Stikine and Iskat Rivers the contact i s i r r e g u l a r © i n this case the irregular i ty is caused by different intrusive masses© s Between TTa&s River and the Skeena the contact i s irregular, numerous large spurs projecting out from the main contact. Also there are numerous stocks. In the v i c in i ty of Zymoetz River the contact as exposed is 1 irregular and Hanson believes that mineral deposits up to 20 miles east of the contact were deposited by solutions r i s ing ver t ica l ly from the batholith. Unless the contact was dipping gently these deposits would not occur so far away. 2 Dolmage i n the section along the batholith from Tatla to Bel la Coola noted a change in the dip of the contact within that area. Near Kl ina-Kl in in the southeast, the contact is nearly ver t ica l , whereas i n the northwest the contact appears to be nearly f l a t ® 3 The explanation offered by Schofield t for the steep dip of the contact generally found, is that the western flank of the batholith may have been depressed relat ive to the eastern flank, thus causing a greater rate of erosion on the eastern flank so that the batholithic contact now exposed on this flank is well down on the side of the batholith. In view of the exceptions noted above, which indicate that some 1. Hanson, G. Proceed. R. S. 0. 1927, V o l . p. 2. Dolmage, V* S« R» 1925, Pt . A, p « 161 3. schofield, S. J . Memoir 132. p . 66 parts of the batholith dip only gently under the surface, the explanation could s t i l l be used. i f i t was considered that the depression of the western flank occurred before the batholithic intrusions had been com-pleted. The older phases then would* because of their greater erosion, have a consistently steeply dipping contact, while younger phases would have a variable dipping contact, in some cases steep and i n others shallow, (i) Contact Metamorphism In general the amount of metamorphism to which the intruded rocks have been subjected is s l ight . This is one reason why i t i s believed that the roof ro cks over the batholith have been ramoved along the eastern contact because generally there is a greater metamorphism of the roof rocks than of those rocks adjacent to the contact at the side of the 1 intrusive • 2 Cairnes speaking of the Wheat on d i s t r i c t says that, "The only apparent effect that the granitic magma has had on i t s walls is to cause a recrystal l izat ion of materials to s ome extent, and thus give them a denser texture. Even this metamorphism extends only a few feet from the intrusive border." Similarly, the amount of contact metamorphism caused by the batholith elsewhere along this contact appears to be small, inasmuch as i t i s seldom mentioned. The sediments of the Hazelton group on the Skeena near the 4 contaet become hard and cherty, while rocks of the same group near Eutsuk 5 Lake become s i l i c i f i e d and coated with epidote. DoImage says that, "Where 1. Schofield, S. J . Man. 76, 1915, p. 83 2. Cairnes, D. D. Mem. 31, 1912, p . 76 3. Hanson, G. S. R. 1924, P t . A. p . 40 4. Marshall, J . R. S. R. 1925, P t . A, p . 150 5. Dolmage, V. S. R. 1925, Pt. A, p. 161 -4S«* metamorphism is marked • « • the sediments are converted almost entirely to biotite for distances from the contact ranging up to 100 feet." This lack of metamorphism can not be accounted for by lack of rocks amenable to metamorphism because most types are present somewhere along the contact* It may indicate, however, that the intruding magma was mobile and also under considerable pressure, so that i t stoped off blocks of the intruded rock easily and quickly and did not find i t s e l f i n one loca l i ty for any great time© (j) Method of Intrusion. 1 Both Cairnes and Gockfield believe that the batholith intruded i t s e l f by means of overhead s toping. They believe that tongaes and dykes intruded ahead of the magma and surrounded large blocks which then sank i n the magma. They do not find evidence of minute interfingering of the granite and older rocks and believe that the assimilation near the top of the intrusive did not play an important part . The stoped off blocks prob-ably sank to a considerable depth i n the molten magma before they were assimilated* There are roof pendants a l l along the batholith which are thought to represent the remnants of the roof which original ly covered the batholith u n t i l after i t had been intrudedo 2 Schofield also believes that the rocks surrounding the batho-l i t h were displaced because their strike conforms generally with the strike of the contact, even at the ends, where the strikes bend to conform. 10. Cre taceous» There are no rocks of this age known near the contact in the section north of the Takn area© 1. Cairnes, D. D. Mem. 31, pp 75-77 & Cockfield, T7.E. SR 1926, pt A, pp8-9 2. Schofield, S. J . Private manuscript• -44r (a? Taka to Iskut River There is a great thickness of complexly folded sediments and volcanics in this area, which Kerr has found to consist largely of Triass ic and some Jurassic rocks. Ho rocks of Lower Cretaceous age have been recognized in this thick series, but there may be some present® Unconformably overlying this thick series, i n some places, i s an Upper Cretaceous formation*. In some parts i t consists essentially of con-glomerate which has well rovinded boulders, up to one foot i n diameter, of intrusive rocks. In the east the conglomerates thin out and the pebbles become smaller and beds of sandstone appear. In one section the total thickness exceeds 2000 feet of almost f la t lying sediments. A thin layer of volcanics was also noted near the top of one mountain® (b) Iskut to Zymoetz River Distribution: There are no rocks i n the Portland Canal area known definitely to be Cretaceous, but between the Na$s River and the Skeena, and in the Skeena and Zymoetz River valleys, small areas of Cretaceous strata are found. Lithology: North of Kitsumgallum Lake the formation consists of fine conglomerate and coarse sandstone. A l i t t l e north of these are a r g i l l i t e s , shales and some coal searns• A long the Skeena similar rocks are found- and here the conglomerate pebbles are often granodiorite. In regard to this forraati on Hanson says that the local areas "are remnants of an extensive formation which was present in the val leys . " Age and Correlation: Foss i l s indicative of a lower Cretaceous age 1. Kerr, F . A . S. R. 1928, P t . A, p . 21 2. Hanson, G. SR 1924, p t . A, p . 108 -45-have been found i n this formation to which, the nane Skeena has been applied. It can be correlated with the Skeena formation farther east which is more extens ive® It is not folded closely as the underlying formations are and often there is a very distinct unconformity* (c) Zymoetz-gun Greek Distributions Along this section, Cretaceous rocks are absent u n t i l near the v ic in i ty of Tatla where they appear i n patches, but they become more important the farther south u n t i l they become the most important single formation with the exception of the intrusives* l i thology: The most northerly outcrops of these Cretaceous rocks 1 consist of sandstone, a r g i l l i t e , and a considerable amount of volcanic rock* South o f this , volcanics diminish and there are some conglomerates 2 i n the series. Hear Chilko lake arkoses are important members of the formation s the mineral constituents of which are so fresh that microscop-i c a l l y the rock resembles a tuff. In the Gun Creek area this formation consists mainly of a r g i l l i t e with many beds of sandstone, conglomerate, limestone and some volcanics. The Eldorado formation, which i t is called here, i s at least 20,000 feet thick . In addi t i on to these sediments, i n the Gun Creek area there is a thick series of volcanics, mostly tuffs, with some flows* Their composition ranges from andesitic to basaltic and they are generally porphyritic* Dolmage estimates the thickness to be over 10,000 feet. 1. Dolmage, V* SB 1925, Pt .A , p . 159.& 2* SR 1924, Pt .A, p. 66 &3* SR 1928, Pt .A, p . 82. -46-Age and Correlations Fossi ls are quite abundant i n some of the sedimentary beds and they indicate def initely a lower Cretaceous age for the beds. Some of the more northerly areas do not contain many foss i l s , but they are thought to be also Lower Cretaceous because of their l i t h -ological s imi l a r i t i e s . This thick series is considered to be the equiva-lent of the Eldorado seri es of the Bridge River area. The volcanics are not quite so easy to date. Only plant fossils have been found in some argillaceous beds i n them, which indicate a late Lower Cretaceous or an early Upper Cretaceous age for them. They are intruded by dykes presumably related to the Coast Range intrusives, but since those intrusives are of varying ages that does not set an upper l imit for their age* In some places they overly the Eldorado series conformably. (d} Gun Creek-Fraser River Distributions Cretaceous strata are not abundant areally along this section although local ly they may be present as a thick series. They are found in the northeastern corner of the Bridge River area, in the Pemberton area and are also exposed on the Fraser River. Lithologys The Eldorado series, as described by McCann* consists of sandstones, arg i l l i tes , slates and some massive beds of conglomerate. There are also a few interflows of dense andesite. 2 In the Pemberton area there is a small area of sedimentary rocks varying from coarse conglomerate to shales and slates. They are less deformed than the unaerlying Triassic? rocks. 1. McCann, W. S. Mem. 130 pp 3S-35 2. Cairnes, C. E . SR 1924, P t . A. pp. 60-81 -47-there the Cretaceous sediments are exposed by the Fraser River* they are seen to be composed of conglomerates with some gr i t s and shales. Age and Correlations The Eldorado series, north o f the Bridge River area has been found to be Lower Cretaceous on good foss i l evidence© Those rocks thought to be Cretaceous in the Pemberton area, have not been found to contain foss i l s , but the conglomerate beds contain an abundance of granit ic boulders that probably were derived from erosion of the Coast Range intrusives and so these conglomerates are probably post-Jurassic* Their l i tholog ica l s imilarity to Eldorado series makes i t probable that this s eries also i s Lower Cretaceous in a g e « The beds exposed in the Fraser r i v e r contain Lower Cretaceous fossils and probably were deposited contanporaneously with the Eldorado series further north. A l l these sediments would appear to be part of Daws on»s Queen Charlotte Island formation. 11. Eocene. (a) Taka-Iskat River Distribution: Eocene rocks are found in a couple of small areas along the Stikine r iver a short distance south of Telegraph Creek. 2 Lithology: The series consists chiefly of sediments including con-glomerate, sandstone and shale. The pebbles for the conglomerate appear to have been derived from the underlying volcanics. Some of the sandstones may be tuffaceous* Sear the top of the series there are a few flows and tuffs* Some of the sandstone is very carbonaceous and is combustible. 1. Bowen, I . L * SR 1912, p. 110 2. Kerr, F . A . SR 1928, Pt* A . p . 21 -48-Eocene deposits are not reported from any other section along the contact. 12. post-Eocene Flows (a) Yukon-Atlin Distribution: Locally throughout this area there are small patches of flow rocks of various types. They are a l l probably close to their source which may have been fissures or volcanoes. 1 Lithology: Cockfield puts these volcanics into the 'Newer* and the 'Acid ' groups• The Newer volcanics are andesites and basalts, fresh i n appearance but real ly very much weathered. Some scoria and tuffs are included. They a l l exhibit various colours including black, green, grey, red, pink and white. The flows are generally porphyritic. The Acid volcanics consist of rhyolites , but some acid tuffs and some granite porphyries are also included in this group. They are a l l l ight coloured and quartz is usually abundant. Age and Correlation: The Newer volcanics which include Ca i rnes» Carmacks basalt are considered to be late Tertiary in age, but there is not real ly any definite information on their age except that they are usually the youngest rocks i n any area with the exception of glacial deposi ts. . The Acid volcanics, which include Cairnes' Wheaton River volcanics and Elusha intrusives are considered to be younger even than the Newer 2 volcanics because in the Wheaton d i s t r i c t , Cairnes found them cutting the Carmacks basalt. They probably formed just before the glacial period, because they conform with the topographic features that existed just prior to giaciat ion. 1. Cockfield, \7. E . Mem.. 150, pp. 35-35 2. Cairnes, D. D. Mem. 31, pp. 64-55 -49-(b) Taku-Iskut Biver fhere are no Tertiary rooks of post-Eooene age known near the contact i n this section* (c) Iskat-gymoetz Biver Distribution: Bocks of this age along this section are confined to a few areas east of Alice Arm 1* They total only a few square miles* l i thology: There are several hundred feet of lava flows i n beds 10 to 50 feet thick. The most common type is an enstatite andesite. a l -though there are some basalts. These lavas are mostly porphyritic and some are amygduloidal* {&) Zymoetz Biver-Sun Greek Distribution: Tertiary lavas are not abundant near the contact but farther east they are the most important rock. At intervals along this section areas of these lavas extend out over the other rocks towards the contact, and near Tat la these flows cover the contact. Lithology: Near Eutsuk Lake there is a series consisting of con-glomerates, sandstones, ashes and lavas. Most of the lavas are basaltic and vesicular. In the rest of this section, the sediments do not appear to be 3 present, and with the exception of a l i t t l e rhyolite a l l the flows are basalt ic . Age and Correlations No fossi ls have been found i n these flows so the age i s uncertain. They are a l l nearly f l a t - ly ing and rest uncon-1. Hanson, G. S.B. 1922, Pt .A, p . 43 2. Brock, fi. W* S.B. 1920, Pt .A , p . 89 3. Dolmage, V . S.B. 1925, Pt .A, p . 162 -50-formably on the older formations. This would indicate that they are Tertiary i n age. They are believed to be equivalent to Dawson*s "Upper Volcanics" 1 which are classed as Miocene in age. These flow rocks are real ly westward extensions of the great flows which cover such a large part of the interior of B r i t i s h Columbia and United States, (e) Qnn Creek-Fraser River Distribution: There are a few surface flows exposed a few miles north of the contact in the Bridge River area. They overly a thin sedimentary series which is barely exposed. 2 Lithology: In the Bridge River area there is a stock, several s i l l s and a flow, a l l of which are believed to be contemporaneous i n age and to have a common o r i g i n . They are a l l f a i r l y acidic in composition and are porphyries. The flow overlies a series of shales, sandstones and conglomerates which contain some thin l ign i te seams. Age and Correlations Mo fossi ls have been found i n the sedimentary series and i t is doubtfully referred to the Coldwater series of the interior , of Oligocene age. The flow is later than this and so are the intrusives, so i t i s l i k e l y that these are a l l Miocene in age. 12. Pleistocene and Recent Generals Covering the older formations are great thicknesses of glacial and post-glacial material. This material is unconsolidated and is readily recognizable. It is confined chiefly to the valleys but sometimes covers the other rocks, even at high elevations. This material i s found discontinuously throughout the area. 1. Brock, R. W. SR 1920, Pt .A, p. 89 & DoImage, V. SR 1924, Pt .A, p . 68 2. McCarm, W. S. Mem 130, pp. 39-40 l ithologyj There are a great many types of material of this age, of which the most abundant are morsinal deposits, gravels, sands, boulder clays, s i l t s , mucks, soi ls and some peat. In a few places also there are recent lava flows lying on top of this unconsolidated material. CHAPTER IV STRUCTURAL GEOLOGY There are three divisions into which the rocks along this area can he grouped for purposes of considering the structural geology., They ares (1) the pre-batholithic rocks, (2) the rocks of the batholith and (3) the post-batholitMc rocks* The pre-batholithic rocks, which consist of about equal amounts of sediments and volcanics, near the contact with the batholith are closely folded into anticlines and synclines. Often these folds are i soc l ina l and some have been overturned. Insufficient work has been done i n most cases to decipher the detailed structure, but enough has been done to know that these pre-batholithic rocks are generally folded so that they dip at high angles and strike pa ra l l e l to the trend of the batholith. The closeness of the folds decreases towards the east, the folds where exposed being more or less open. It has been said that*, "The sedimentary rocks flanking the Coast Range batholiths are folded more closely near the batholith and more openly at a distance, so that, though their general trend is para l le l to the coast, their dip is extremely variable, ranging from north easterly to south westerly at a l l angles." While a l l the pr e-batholi thi c rocks near the contact are folded 2 Kerr thinks that the Palaeozoic rocks were f i r s t folded with axes trending northeast and southwest and later the sediments were again 3 folded with axes trending northwest and southeast. The Wrights also 1. Wright, EE and Wright CW, USGS Bul l 347, p . 62 (1908) & 3 . p . 39 2. Kerr, F . A . SR 1928, P t . A . p . 19 -53-found evidence to indicate folds that had axes trending northeast and southweste The batholithic rocks often are gneissose and the strike of the trend of the minerals i s northwest. Often also the rocks are -Jointed and these joints , which make large sheets o f rock, generally strike northwest and dip northeast. Overlying unconformahly these rocks, are the post-"batholithic rocks, the oldest of which in some cases are Lower Cretaceous. These in some cases are folded in open folds and their dips are usually low. The younger ones, the Tertiary volcanics, generally dip at low angles "but their dips are constant and they are not folded. There are two major directions of fissuring i n Br i t i sh Columbia* northeast-southwest and northwest-southeast, which control many topo-graphical features as well as the direction of fissure veins. These fissures, or faults or shear jones are the result of compressive stresses which probably commenced before the igneous intrusions and which probably caused the northwest southeast folding to take place, immediately prior to the batholithic intrusions. 1. Schofield, 3. J . C.I.M.M. Trans, v o l . 28, pp. 428-433, 1925. CHAPTER 7  GEOLOGICAL HISTORY A series of metamorphosed sedimentary rocks, presumably late pre-Cambrian in age, i s evidence that there was a sinking basin of sedimentation, at least in the northern part of the area, i n pre-Cambrian times. The source of the materials deposited in this sea, Is believed to have been an ancient mass called Cascadia, which Is now hidden by the waters of the Pacif ic Ocean* The fact that, included in this series are schists which are thought to have been derived from basic flows, indicates that even in those times there was considerable vulcanism. Similarly, the inclusion in this group of rocks, of granite gneiss i s an indication that before Cambrian times there were igneous intrusions which probably were intruded coincident with a period of diastrophism* Succeeding this diastrophism, there probably was a long period of erosion when the intrusives were unroofed and the material deposited elsewhere* This erosion probably continued u n t i l Devonian times at least, when again there was a period of sedimentation i n the north* This sedimentation was possibly followed by igneous act ivity on a small scale. In upper Palaeozoic times, there was another sea i n which sediments were l a i d down, and for the f i r s t time this sea extended the length of the area. This sea may not have been continuous from north to south but may have been a seri es of seas in which marine sediments were l a i d down. There was some vulcanism at this time but its products are less abundant than those produced by normal processes of sedimentation* Towards the close of the Palaeozoic i t would appear as i f there were an up l i f t of most of the area and in Permian times, as far as most of the area is considered, i t must have been a period of erosion. There -55~ remained one sea however, where the Stikine river now flows, in which massive beds of limestone formed* After this interval of erosion, in the Tr ias s ic , seaways ex-tended over the greater part of the area, hut the greater part of the material that was deposited in them was of volcanic origin rather than sediments formed from erosion products. Only i n the Yukon and in the Zymoetz River area are volcanics of minor importance. Elsewhere i n the area, flows, tuffs, breccias, and agglomerates make up the greater portion of the rocks. It is known that the vulcauism was intermittent because of the occasional interbeds of a r g i l l i t e and limestone which are found. This period may have closed with some orogenic ac t iv i ty and igneous intrusion* The seas spread over this area again i n the Jurassic period and volcanic ac t iv i ty was again of major importance* Stratif ied rocks of this age are unknown in the southern part of the area and the seas may not have extended the f u l l length. Compensating for this areal shortage i s the great "thickness of these rocks where they are found. In several instances there i s at least 10,000 feet and in some cases over 15,000 feet of these rocks are exposed. The tota l thickness of the volcanic members is greater than that of the ordinary marine sediments. At the close of this period the Coast Range mountains were built and simultaneously there were great granitic intrusions. While they were being elevated and after they had been elevated these high mountains were rapidly eroded. These mountains were in approximately the same position as the present Coast Range and the center l ine of the batholith would represent approximately their core* These mountains, the highest of which were to the west of this contact area, were sufficiently eroded by Lower Cretaceous times to ex-pose the intrusive masses and when deposition commenced In this area, pebbles from these masses were la id down i n conglomerates* These conglomerates and overlying rocks often rest unconformably on the underlying formations. These Cretaceous formations are only found loca l ly and i t is believed that they were l a id down i n shallow inland seas or lakes east of the Jurassic mountains. The coal seams often found in the formations of the beginning of this period are also indications that these formations were l a id down in fresh water. In some cases this Lower Cretaceous formation exceeds 20,000 feet in thickness. Sometimes interbedded with and sametinss over lying this fresh-water sedimentary series are volcanics, including flows and tuffs ranging from andesitic to basaltic. In certain instances the thickness of this volcanic series may be over 10,000 feet, indicating a tremendous volume of volcanic material. In Upper Cretaceous times this area was probably s l ight ly elevated so that erosion became the dominant process. Only in the Stikine area is there a formation of this age. There appears to have been a cessation of volcanic ac t iv i ty at this time for only one flow of this age is found in that area. It is uncertain whether or not there was mountain building during the Cretaceous or whether the mountain building was confined to the close of the Cretaceous during the luramide revolution. At any rate, by the end of the Cretaceous, the Coast Range, which was practical ly a peneplain was upl i f ted and at the same time there were more intrusions on a large scale. Following this up l i f t , erosion once more became highly ef-fective and has continued u n t i l the present day over the greater part of the area* During Tertiary times there were a few fresh-water basins of sedimentation, although these are of minor importance* The feature of this period were the great lava flows which spread over the surface* These i n some cases are very thick, although they reach their maximum de-velopment further east in the inter ior . Some of these flows are andesitic but most are basalt ic . At the close of the Tertiary, i t began to get colder and the glaciars grew and advanced down the valleys, forming many topographic features as we see them now. The great weight of ice caused the western portion of Br i t i sh Columbia to subside in relat ion to the ocean so that by the time the glaciars retreated the sea advanced into the glaciated valleys along the coast. At the present time the glaciars are retreating and they may readvance at some future date© (58) CHAPTER Ylt MINERAL DEPOSITS Introduction In this chapter, the deposits discussed w i l l he limited to those which are present because of the batholithic intrusions. This includes magmatic segregations, pegmatites, hydrothemal veins and contact inetamorphic deposits, and excludes placer deposits and sediment-ary deposits such as coal, nei ther of which are peculiar to a batholithic contact area© Production From the deposits along a batholithic contact such as this one i t might be expected that the mineral production would be diversif ied because of the various ages and types of intrusives and because of the varied types of intruded rocks. This is not the case, for almost 99% of the value of the total production from these deposits i s from gold and s i lver . There has been some lead produced and small quantities only of zinc, copper and molybdenum. The approximate valuefor these metals produced u n t i l the end of 1954 i s : g o l d—§ 4 5 , 0 0 0 , 0 0 0 ; silver—$20,000,000; and l e a d — § 1 , 0 0 0 , 0 0 0 ; the value of the other metals i s unimportant. 1 One reason for this great proportion of gold and s i lver relative to copper is that the gold and s i lver come from lower temperature deposits than the copper does and that most of the higher temperature copper deposits have been removed by erosion. • Another reason for the large percentage of gold and si lver to the total production is that the area is far from being completely developed and because i t is an interior contact high-grade precious metal deposits are more readily developed than are large low-grade base metal 1. Schofield, S. J . Memoir 132, 1922. pp. 64-66 -59-deposits. The precious metals are readily amenable to concentration,, whereas the recovery of the base metals requires the use of a smelter, which means either a large capital outlay or else high transportation charges to the nearest smelter. The mineral deposits wi l l be described i n order of their occurrence along the contact, more attention being given to those from which there has been some production. 1 Si1tana Lake Discovered about thir ty years ago but very l i t t l e work has been done on these claims, which are on both sides of Giltana Lake. On the northeast side of the lake, a metamorphic sedimentary series, including schist, quartzite and limestone, i s mineralized with magnetite, chalcopyrite and malachite. The individual ore zones average about 6 to 10 feet in width and the mineralization came from the same source as some nearby granite. Gold and s i lver are only found i n traces, the valuable metal being copper, o f which there is i n some cases 9fU - The deposits on the northwest side of the lake are too small to be economically important. 2 Whitehorse A few miles west of the town o f Whitehorse, there are copper depos its which have been productive i n the past but which are not operating now. While some production has come from these deposits, i t has not been very profitable because of the irregularity of the deposits and values. 1. Cairnes, D. D. j&em. 5, 1910. Appendix 11, pp. 55-56 and Cockfield, We E . SR 1926, P t . A. " p . 12 2. McConnell, R. G. "Whitehorse Copper Belt" G.S.C. 1909 and Cockfield, W. E . SR 1927, ? t . A . pp. 14-16 -60™ (1) Geology The oldest rock in the v i c in i ty of the deposits i s a pure crystall ine limestone of Carboniferous age. Intruded into the limestone, mostly as sheets, are thick bodies of fine-grained porphyrites. These are massive and jointed. They do not have much effect on the limestones which they cut nor are they metamorphosed greatly by the granite which cuts them. This granite which is grey or reddish has an exceedingly irregular contact with the limestone and i t Is along this contact that most of the deposits occur. It Is a. hornblende granite with some more basic facies, including quartz diorite and d ior i te . The copper belt, which i s about 12 miles i n length, includes a l l the -deposits. These are most abundant i n the limestone just at the contact with, the granite, but are also found In the limestone at some distance from the contact and where the zone of contact metamorphism i s wide, some contact metamorphic minerals are found in the grani te© (2) Mineralogy The non-metallic gangae minerals are such as are character-i s t i c a l l y developed upon the introduction of hot s i l ic ious solutions into limestone. They include andradite garnet, augite, tremolite, more l ike ly wollastonite, epidote, calcite , c l inoclore, s erpentine, actinolite and quartz, of which the last four are present only in small amounts© Somite and chalcopyri te are the most important copper minerals, the others being tetrahedrite, chalcocite, malachite, azurite, chrysocolla, cuprite and malaconite, of which the last five are formed by the surface oxidation of the primary su lphides© Cuprite and native copper have also been found. Most of the iron present is found as the oxides hematite or magnetite, pyrite and pyrrhotite occurring only i n small quantities© Other metal l i e s found, though not very important, are arsen-opyrite, sphalerite, molybdenite, stibnite, gold and silver, (S) Origin The mode of occurrence of the deposits, (at the contact of an easily replaced rock such as limestone and an intrusive) and the mineralization, are considered good evidence that the deposits are the results of contact metamorphism, The presence of stibnite, which i s usually indicative of a low-temperature of deposition, i n this case may indicate that there was a rapid temperature decrease away from the in-trusive and that a l l the deposition may have taken place closer to the surface than i s usual i n this type of deposi t. It is believed in this case, as in similar instances, that the minerals found at the contact are formed by the reaction between siliclous fluids and the calcium carbonate of the rocks and that these fluids came from the same magma from which the adjoining intrusive s o l i d i f i ed. The granite is probably Upper Jurassic in age and the deposits were probably formed at that time also* 1 Wheaton and Windy Arm (1) Introduction, These areas are i n southern Yukon, and some claims in them have been extensively developed and there has been some production. Most of the claims were located about 30 years ago but recently they have been untouched. There are many deposits in these areas, but for convenience of 1. Cockfield, W. E. Mem, 150, pp. 38-81, 1926, and Cairnes, D, D. SR 1916, p. 34 and Mem. 31, pp, 85-145, 1915 description.they can be described under 4 main headings. These ares I. Gold-silver quartz veins; 2. Antimony-silver veins; 3. Silver-lead veins? 4. Contact metamorphic d e p o s i t s ® (2) Gold-silver quartz veins a. Distribution & Occurrences These veins occur i n a belt which, i n a general way, parallels the trend of the Coast Range and most of the veins str ike para l le l to this belt. Most of them have steep dips to the east. In the "Wheaton area most.of the veins occur in the Coast Range intrusives and. i n the Windy Arm area, most of them occur i n andesites. In both areas, some veins are found in other types.of rock, including the Mt« Stevens schist, in which cases they are very irregular. Some are as much as 12 feet wide, but the average is about 3 or 4 feet* b. Mineralogys The vein f i l l i n g material i s quarts, although occasion-a l ly there are small amounts of barite and ca lc i te . Galena i s the most characteristic metallic mineral and is accompanied by more or less pyrite, arsenopyrite, chalcopyri te, tetrahedrite and stibnite. Other rarer minerals found include argentite, pyrargenite, jamesonite, chalcocite, yukonite, native gold and s i lver and tellurides with i n some places a small depth of oxidation products. In no case does the zone of oxidation extend more than 30 feet from the surface and i t is usually less. No secondary enrichment has been noted. Co Origins The great variety of minerals that has been found may i n -dicate that not a l l these veins should be placed i n one class, but there is not enough evidence to put them i n two or more classes. The veins may have had more than one source, so that the minerals i n one vein may have been deposi ted at a high temperature and those of a nearby vein at a -63-lower temperature* Some of the veins occur in the Coast range intrusives and i f they are a l l considered to he pract ica l ly contemporaneous then they must a l l he younger than the intrusion. On the other hand, some of them are cut by a l l the other younger intrusions, so i t is most l i ke ly that the veinsware formed towards the close of the Coast Range intrusion, when the outer part of the intrusives had cooled, and part of the interior was s t i l l molten. Cairnes believes that these veins belong i n the upper vein zone which i s probably equivalent to the epithermal zone as defined by Idndgren"* (5) S i lver Antimony-Quartz veins These veins are confined to an area that' extends across Wheaton River near i t s source. They are most abundantly developed on Carbon o 1 o 1 H i l l at latitude 10 10 and west longitude 135 15 . The veins occur either i n the Coast range intrusives or else i n the andesites or breccias of the Older Volcanics. They average about 2 feet in width, though widths up to s ix feet are known. Stibnite is the characteristic metallic mineral and i n some cases forms the bulk of the ve in . In these cases i t i s accompanied by sphalerite and james-omite. Quartz i s the most abundant gangue mineral and sometimes i s ac-companied with barite and calcite i n small amounts. Veins richer i n si lver than i n antimony have galena and tetrahedrite and only minor amounts of st ibnite. The better grade s i lver ores have 100 to 200 ounces of s i lver per ton, while the best stibnite ores carry up to 65 per cent antimony® Cockfield believes that these veins belong in the upper i c i n zone and that they were formed from Igneous emanations from the Coast Range batholith after the outer portion of the intrusions had cooled sufficiently to have s o l i d i f i ed. (4) Silver-Lead Quartz veins These veins are found only i n a small area on Idaho H i l l , latitude 60°20 1 and west longitude 135°. They have been described as a separate type but really their mineralogy indicates that they are closely related to gold-silver veins. They occur in arkoses of the Laberge series and are narrow and tabular, but are irregular and are not well defined. Quartz is the most abundant mineral, although in some parts calcite is more abundant. The metallic minerals are galena, arsenopyrite sphalerite, pyrite and chalcopyrite. Gold i s rarely present to the value of $2 per ton. The higher grade ores assay about 50 ounces silver per ton and up to 40 per cent lead. These veins are somewhat different from the other types previously described, because they appear to have been foamed by meta-somatism of the country rock rather than by the f i l l i n g of fissures® They are probably of the same age and formed from the same magma from which the other veins were. (5j Contact Metamorphic Only one deposit of this type Is known of In the Wheaton area. It is located just south of the valley of the Wheaton River, where i t starts to trend eastward. This deposit l i e s at the contact of the Coast Range grano-diorite with hornblende gneiss. The minerals found are magnetite. k-65-. specularite, chalcopyrite, pyr i te , quartz, calcite , epidote, act inolite and garnet. There is about 1% copper and about $2 gold per ton® 1 A t l i n Dis t r ic t Lode deposits are numerous i n the v ic in i ty of A t l i n Lake and Taku Arm of Tagish Lake, but most of them have not been extensively developed* They may be classed ass 1. quartz veins i n which gold and s i lver are the important metals. Other deposits o f lesser importance can be classed as: 2 . s i lver-lead veins, 3* copper veins and antimony veins, and 5 . contact me tarnorp hie deposits* (1) Quartz veins a* Occurrences Quartz veins of the f i r s t type, and containing tellurium, are found on Tagish Lake, 12 miles south of Golden Gate* Quartz veins containing si lver as well as gold are the most abundant in the area. In one case, on Table Mountain, this type is cupriferous. The gold-silver type occurs i n a variety of formations, including ch lor i t i c and micaceous schists, basic volcanics and grano-dior i te . So general trend of their strikes and dips have been noticed, most of them being controlled by local structures*, b* Mineralogy; Quartz i s the most important vein mineral. Oalcite is also present i n some veins . Galena, pyri te , chalcopyrite and tetrahedrite are the most common metallic minerals* native gold and s i lver also occur, generally the gold being more valuable than the s i lver* A few contain some tellurides and some native antimony* The Engineer mine and the A t l i n Paci f ic (ForgoId) mine which is also of this type, have been extensively developed and there has been some production from them, but at the present time they are not being 1* Cairnes, D.D. Mem* 37, CGS pp* 72-121 and Cockfield, W* E* SE 1930 Pt* A* pp 11-16 -66-exploited© 1 c Engineer Mines The Engineer mine , upon which a great deal of de-velopment has been carried out, was discovered many years ago and there lias b e e n some production from i t . i t i s on the shore of Tagish Lake, 12 miles south of Golden Gate. The mineral deposits occur i n a r g i l l i t e s and greywackes of the Laberge series not far from granodiorite satellites of the Coast range batholith. Attention was f i r s t attracted to two large hubs or stockworks of quartz and country rock. To date these have not proved to be capable of profitable exploitation® Later development was concentrated on 2 numerous narrow quartz veins which were thought to radiate from these stockworks« Generally these veins are less than 2 feet in width but underground they are found i n some cases to become as wide as 8 feet. These veins, which have a quartz gangue, have a distinctive mineralogy which includes the minerals native gold, mariposite, a telluride probably caiaverite, pyrite and allenontite, (a compound of native arsenic and native antimony.) These veins are now believed to be connected i n some way wi th a well defined shear zone, and that they are given off from this zone at Intervals at varying angles* In places this zone is well mineralized with quartz and pyrite and i n places carries good values over large widths. There i s a possibility that this may be developed.into a large tonnage of low grade ore. In places i t is 65 feet wide and com-mercial values have been found extending over a width of 14 feet© 1. Cockfield, W. E . S.R,, pt. A», 1925© pp. 11-15 2. Cairnes, D« D» Mem, 37, pp. 73-89 d e Origin: Cairnes i s of the opinion that a l l these veins are genetically related to the intrusives of the Coast range batholith which in^ every instance are exposed not far from the veins. He also believes that their mineral go 7/ i s indicative of their being deposited in the upper vein zone a (2) Silver ^ead Veins a* Occurrences These veins are restricted to Jit. Leonard about 14 miles from A t l i n . The At l i n Ruffner property, the most extensively developed of this type, occurs here* Dykes of hornblende lamprophyres have been intruded into a light grey coarse granite which i s similar to some phases of the Coast range intrusives. These dykes, which are up to 40 feet wide, have been fissured and the fissures have been f i l l e d and the brecciated dykes partially replaced. The mineralized zones within the dykes are tubular but irregalar* b. Mineralogy: The gangue minerals are quartz, calci te and ankerite, while the metallic minerals include galena, arsenopyrite sphalerite^ pyrite, chalcopyrite, marcasite, pyrrhotite, and pyjaargerite. Few of the smaller dykes are mineralized, probably because they did not fracture. c. Origins Okulitch 1 believes that the ore bearing solutions circu-lated during the 2nd period of mineralization following the intrusion of the C. R. bath^'fthe Oligocene) because he believes that the dykes f i l l e d fissures formed in Ln ram id e revolution (Eocene) and that the dykes were fractured and then their fissures r e f i l l e d i n the next period of erogenic activity, the- Oligocene© On the other hand, i t i s commonly considered that lamprophyric 1. Okulitch, V. J . Masters Thesis U.3.C. 1932, pp. 143-144 dykes are a late phase coming from an intrusive magma and follow the consolidation of the main intrusive "but are of the same kind of intrusion Similarly, i t i s commonly believed that hydrothemal solutions are even younger than the lamprophyres and that they commonly cut them, even when the source of both materials Is the same. It seems, then, there is no reason for believing these veins to be much younger than similar veins found elsewhere along the eastern contact and that they are real ly Upper Jurassic In age® ( 5 ) Popper Teins Deposits of this and the following classes have not been extensively developed. These veins occur only on Copper Island at the southern end of A t l i n Lake. They consist of thin ca lc i te veins in olivine ba sa l t s® Masses of native copper are found in. these veins as well as some secondary copper stains. While the veins have not been prospected at depth, Cairnes believes that the copper was original ly deposited in the native state from ascending solutions and was not formed from the oxidation of some copper sulphides. f4l Antimony Veins These have been noted to occur only in one place, 10 miles north of Golden Gate on the west side of Taku Arm. The deposits consist of bedded veins i n the a rg i l l i t e s of the Laberge series• The main vein is up to 4 feet wide and consists of quartz and stibnite and galena. Considerable quantities of a r g i l l i t e are intercalated in the veins* -69-(5) Contact Metsmorphic Deposits These occur at the contact of granodiorite of the Coast' range batholith with amphibolites, schists and limestone of the Mt. Stevens series on Hoboe Creek, southwest of A t l i n Lake. The minerals found are magnetite, hematite, chalcopyrite tetrahedrite, yellow garnet, b iot i te , and other s i l i ca tes . Limestone has been replaced in preference to the other members of the Mt. Stevens group which occur near the contact. In some cases the deposit is a 150 feet wide but the depth to which i t extends is unknown. A good part of the deposit may average 5% copper and there are small amounts of gold and s i lver throughout. 1 Taku Area (11 Introduction The portion of the contact included in this section is that part of i t that is accessible by means of Taku River and i t s tr ibutaries . This is the most northerly river that has a valley through the Coast range. Prior to 1925 this area received l i t t l e notice and was incompletely pros-pected, but since then considerable development has been carried out© There has been no production yet from any of the prospects, but several have good poss ib i l i t i e s , particularly i f there is an increase in base metal prices. (2) Class i f icat ion A l l the deposits so far reported on are irregular replace-ment deposi ts, although on the basis of mineralogical differences two types have been recognized. The most abundant and the most extensively developed consists of copper, zinc, lead and iron sulphides with low 1 . Kerr, F. A . S.R. 1952-All-pp. 15-28; 3.R. 1930-A-pp* 17-40; S.R.1929-16329 values in gold and silver i n a quartz gangue in which barite and calcite are also common. She second type which has similar occurrences but different mineralogy has important amounts of stibnite, the antimony sulphide,and iron sulphide with only small amounts of copper, lead and zinc. In this type the gold values may be quite high although the silver values are generally low. This gangue Is practically only quartz® Most of the deposits are irregular replacements i n altered and sheared zones of Mesozoic volcanics. Often these altered zones i n the volcanics occur at the contact of the volcanics with non-calcareous sediments. One deposit is a replacement i n limestone (the potlach-? Banker.) Most of these shear zones, which appear rusty on the surface, strike parallel to the local structural features although there is a tendency for most of them to strike about north ani south parallel to the main structures. (5) Metasomatism In most cases the original rock, of the altered zones i n which the mineral deposits are found, were probably andesites. At the present time the rock i s either lightcoloured, consisting of quartz, white mica, pyrite, alMte, and some bleached chlorite or else is dark to green i n colour and consists of chlorite, pyrite, albite and quartz. The contrast in colour being mostly due to the presence or absence of chlorite, Kerr believes that these alterations from the original andesites were brought about by hot solutions prior to the deposition of the ore minerals. In some cases where the deposits are like veins these alteration zones may be considered as similar to those ordinarily formed by hydrothermal solutions, which usually are found adjacent to the veins. Shearing i s quite extensive and probably was the reason for the location of the zones. In some cases, dykes were intruded along the shear zones some time before the mineralizing solutions stopped circulat ing. In general, the more extensive the shearing, the wider is the zone and the mineral deposit* (4) Occurrence The deposits consist of discontinuous lenses which l i e in approximately the same plane in the zone. At f i r s t there was a great deal of pyri te deposited, by replacing the country rock. Later, the nature of the solutions changed and more complex solutions started to circulate which found i t easier to replace the pyrite than the adjacent country rock so the mineral deposits are confined to loca l i t ies where there was quite a large deposition of pyri te . The minerals deposited by these later solutions include sphalerite, chalcopyrite, galena, and in the case of the antimony-rich deposits, stibnite and arsenopyrite. The gold in this latter case appears to be i n solid solution in the arsenopyrite which occurs as peculiar needle-shaped crystals. These antimony-rich deposits more nearly resemble veins and the lenses are sometimes connected by short veinlets of quartz. The rocks i n the area which appear to have been unfavourable for the deposition of the ore minerals are the Mesozoic and Palaeozoic non-calcareous sediments, in which no important mineralization i s known to occur* ?5) Origin Kerr believes that a series of small satel l i tes , some distance -72-east of the main contact, were the source of the mineralizing s o l u t i o n s « He believes that these are of the same age. as some phases of the batho-l i t h . Stikine-Iskut Area (1) General Considerations This is the next section of the eastern contact of the batho-l i t h that is re lat ively easily accessible. The intervening area between the Taku and the Stikine drainage systems is not easy of access and a reconnaissance party which passed through i t * did not find any outstanding prospects so i t w i l l not, in a l l probability, be developed for some considerable time. An area up to 25 miles in width and close to 100 miles i n length, of rocks favorably located as to mineralization, can be reached from the Stikine River and i t s tributaries. This area i s much larger than that accessible from similar rivers of equal size because for a good portion of i t s length the Stikine River follows a course which i s not at great variance to that of the contact in this area, and also because the area marginal to the batholith i s wider than at most places. This greater width i s due to the variety of intrusions which make i t probable that i n some instances the interior portions of older intrusions, unfavorable i n most instances as regards mineralization, may have been mineralized by solutions from the younger intrusives. Kerr has found that three and possibly more phases of the batholithic intrusives have associated mineral deposi ts . Although the area has been incompletely prospected^ partly due to the shortness of the f ie ld season, mineralization has been found to be i. Kerr, p . A. S.R. 1930, Pt .A: S.R. 1925, Pt .A; SR 1928 Pt .A; SR 1929 Pt .A. -73-abundant and there are a great variety of prospects. Host of the deposits consist of mixed sulphides such as pyrite, pyrhotite, galena, sphalerite, chalcopyrite, tetrahedri te and bormite, although not a l l of these are found i n the same deposit. lead, copper and zinc are the mose important metals although there are a few veins i n which gold and s i lver are the most valuable. Mos t 'of the deposits occur as irregular replacements, particularly in the limestone of the pre-Mesozoic rocks. Other replacements are found i n the Mesozoic volcanics* None of the prospects have been developed to any great extent* Many of them have been examined by surface trenches but this method generally does not supply sufficient evidence as to the continuation of the ore in depth, although in some cases, natural sections reveal that some of the depos i t s are very errat ic* (2) General Description There are some stringers near Kahtate River which i s a large tributary of the Stikine below the Iskut* These stringers contain considerable proportions of tetrahedrite and chalcopyrite. About 8 miles from the mouth of the Iskut River (on the nor th side) there is a zone in which tetrahedrite, chalcopyrite, galena and sphalerite are abundant and they carry fa i r s i lver values. Along Craig River there are replacement deposits of galena, and chalcopyrite i n limestone. In the Iskut area there are some masses o f orthoclase porphyry pract ical ly a l l of which have some associated deposits of mixed sulphides replacing volcanics and the intrusives themselves are commonly impregnated with pyrites . One property, that of the Iskut Mining Company, has been developed over a considerable length of time* It consists of a replace-meat of either a thin limestone bed or the basal member of a volcanic series and occurs at the contact of the Palaeozoic sediments and the liesozoic volcanics. Although the maximum width i s only about 10 feet the replacement has been carried on over great distances so that there is a mineralized zone possibly several miles long* One of the three sulphides arsenopyri te, pyrite or pyrrhotite usually predominates and may be accompanied by small amounts of chalcopyrite, sphalerite and galena To the east of this narrow zone there is a large area in which the minerals seem to have replaced a considerable thickness of vol-canics and in part some l imes tone» The deposits occur only near a small porphyry mass. Mineralization consists of the following sulphides disseminated through the altered zone and the periphery of the porphyry mass; pyrite, arsenopyri te, pyrrhotite, chalcopyrite, galena, sphalerite, tetrahedrite, molybdenite and also the oxides magnetite and hematite. South of the Chutine River about 4 miles above i t s mouth are the Jackson claims where there is a shear zone about 6 feet wide i n which sphalerite, galena and chalcopyrite occurs A similar shear zone occurs on the Limpoke group at Latimers Landing on the north fork of the Chutine although the minerals found i n this shear are chalcopyrite and borBite© Replacement zones containing copper minerals are found on the August claim which i s about 2 miles east of Kirks Landing on the Stikine, where the minerals are chalcopyrite and bornite. A s i l i c i f i e d and pyrr-hotized zone i n lavas, containing chalcopyrite occurs at the Glenora and King claims 7 miles west of Telegraph Creek. Among the most promising prospects are the Drapich, Elbow Mountain and Devils Elbow contact metaraorphic deposits. The.Drapich -75-consists of inclusions of limestone in quartz diorite which have been replaced by magnetite, speeularite, pyrite , chalcopyrite, quartz, s ideri te and rhodochrosite. This deposit i s about mile south of Jackson's Landing* On Elbow Mountain, just north of where the Stikine crosses the International Boundary there is a deposit of magnetite and also a pyr i t i c zone nearby* The deposits occurring on Devil 's Elbow Mountain about 4 miles south of Jackson's Landing are among the most extensively developed in the area. They occur in calcareous sediments at or near their contact wi th a granitic rock which has a great abundance of felspar and which is a granodiorite* This granodiorite has been considerably broken and altered and is cut by numerous fine-grained dykes which in turn have been faulted* The pre-intrusives include calcareous and non-calcareous rocks but the deposits are pract ical ly confined to the calcareous ones* There are two dist inct ive types recognized by their mineralogy although there are gradations from one to the other* Magnetite pyrr-hotite deposits i n which there is some pyri te , chalcopyrite and galena from one type* These generally occur right at the contact and never occur at any great distance away from the granodiorite* The gangae which usually amounts to less than half of the deposits consists of quartz, garnet, epidote and other s i l icates and is green i n color . Galena and sphalerite are the most abundant minerals in the other type* In one lens, chalcopyrite i s the most important mineral* \ The gangue i n these deposits i s similar to that of the magnetite~pyrr-hotite deposits. These deposits often occur a l i t t l e distance from the contact, part icularly those deposits i n which galena i s the important mineral* -76-Some of the deposits have quite high values i n lead, zinc or copper hut the gold and s i lver values are low. They are found at intervals for over a mile along the contact hut most of the individual deposits appear to he small and as far as they have been developed are as erratic in depth as they are on the surface, although some of the most promising have not been explored. The diversity of prospects discovered both as to character and extent, in the comparatively short time since prospecting real ly commenced, i s a good indication of the mineral wealth of the region® 1 ITnuk Area The next area to the south which is accessible by means of a valley through the mountains i s that of the think River. This is a much smaller river than the stikine to the north and the area tributary to i t is relatively small. About SO years ago there was considerable act ivity in the area and then that died out and up unt i l the last few years very l i t t l e prospecting has been done in this area. Recently, however, interest has been renewed and i n the last few seasons f lying boats have been used to transport the prospectors and their equipment and several discoveries have been made. Ho detailed geological report relating to this area has been published and most of the material regarding i t has been found i n the Annual Reports of the Minister of Mines© At the present time interest is fosussed on quartz stringers and s i l i c i f i e d zones near stocks of diori te . The quartz occurs at the contact of Jurassic flows wi th Jurassic tuffs. Galena and sphalerite are the most important sulphides although there is also some arsenopyrite . 1. Wright, E© E . SR 1905 and chalcopyrite. Some good values in gold have been reported. These deposits are a l l located on Front Plateau which extends westward from the river*, Near the mouth of Sulphide Creek, Wright examined two v en ins . One s tr iking N 2 5 ° Wand dipping 3 0 - 6 0 ° HE about 6 inches wide which con-tained pyri te , sphalerite, tetrahedrite, galena and secondary native s i lver . The other vein strikes IT 5 ° W and dips 8 0 - 8 5 ° E and appears to be up to 50 feet wide. It contains pyrite, galena and occasional particles of sphalerite and chalcopyrite. Above the contact on Canyon Creek, are several veins up to two feet wide which contain auriferous pyrite and also some pyrrhotite, galena, and sphalerite,, They occur in black slates, arg i l l i tes and quartzites, a l l of which have been complexly folded and faulted. Considering the very small amount of exploration work that has been done i n this area i t would appear as i f mineralization was not less intense along this section of the contact than that along more easily accessible areas. Portland Canal (1) Introduction South of the Unuk Biver area for a short distance there is a section along the contact which has been but l i t t l e prospected fend then to the south l ies the Salmon River area. South of this again l ies the Bear and Marmot River areas and s t i l l further south the Alice Arm D i s t r i c t ® Topographically the Salmon, Bear and Marmot River areas constitute one unit and the area at the head of Alice Arm another because -78-of a high divide "between them. Geologically, however, they have many things i n common and w i l l he discussed together. The area adjacent to Observatory Inlet is also generally Included under the name of Portland Canal area but inasmuch as i t differs geologically from the other areas mentioned i t w i l l not be discussed here. Observatory Inlet l ies within the mass of the Coast Range batholith while the other areas mentioned are included in the area along the contact. Portland -Canal area then, includes Salmon, Bear and Marmot _ River areas and the area adjacent to the head of Al ice Arm, and i t w i l l be discussed in greater detail than other areas along the contact because the greater portion of the mineral production of the contact area has come from here. Prospecting commenced i n 1898, and assumed the roportions of a boom about 1910. Production was intermittent from that time u n t i l 1920 when production started at the Premier and since then has been continuous from that property and sporadic at other properties. The chief reason for the development of this area i s that the deposits consist of high grade gold and s i lver ores which are readily developed. The fact that these areas are at the end of long fiords which extend through the Coast Range past the eastern margin of the batholith and thereby make these areas more readily accessible for the prospector, also hasr been of importance i n the development of this area. 1 A recent memoir by Hanson is a compilation of many reports on this area and contains a great deal of the material which is used i n this thesis. Other reports by Burton , DoImage , Hanson , Schofield , 1. Hanson, G» Memoir 175. CGS 1955 2* Burton, Y7. D. Economic Geology, Vo l . 21, pp 586-604 3. DoImage, V. SR 1922, Pt .A, pp 29-33 & Can.Min.Jour. 1920, pp 454-458 4. Hanson, G. SR 1928, Pt .A, pp. 27-49; Memoir 159 (1929) & SR 1931,Pt.A, pp 14-21 5 . SChofiela, S J M e m e 1 3 2 ( 1 9 2 2 ) -79-•1 Smitheringale , were also consulted* (2) General Geology The oldest rocks i n the area are the members of the Hazelton group of Jurassic age* About one hal f of those mapped are of igneous origin* South of Al ice Arm this group i s represented by sediments* Between Alice and Hastings Arm this group i s represented by about equal quantities of sediments and igneous rocks, there being three large masses of igneous rock separated by sediments* In the northern part of the area they are about equal i n quantity and occur irregularly* South o f Alice Arm the sediments are coarse greywackes although to the west near the contact they are a r g i l l i t e s . North o f Al ice Arm the Sediments are a rg i l l i t e s , with a few quartzites and occasionally some interbeds of tuffs* Hear the main batholithic contact there are also some beds of conglomerate and greywacke* 2 In regard to the structure of these sediments Hanson says , "The'strata of Alice Arm di s t r ic t appear to form a northerly striking anticline about 9 miles wide plunging s l ight ly south at the south end and sl ightly nor th at the north end* The anticline is complicated by several f a i r l y prominent smaller folds and has been disturbed by intrusions of later rocks and also to some extent by many minor faults*" Most of the sediments between Marmot and Bear River are a rg i l -l i te s which occur in thick and thin beds. There are also inter beds of quartzite, limestone, tuffs and breccias* Similarly in the northern part of the area a rg i l l i t e s predominate, with minor amounts of greywacke and conglomerate, and there i s often a fine conglomerate intervening between the sedimentary and igneous members of the series* 1. Smitheringale. Economic Geology, Vol* 23, #2, pp* 193-208 20 Hanson, G« Memoir 175,.-p. 2 -80 Locally the sediments are sometimes changed to mica schists along zones of shearing,, In many cases, these a r g i l l i t e s contain mineral deposits so that they are not so unfavorably looked upon as they are In many areas. Included as igneous rocks of the Hazelton group are tuffs, breccias and crystalline rocks. They occur in large irregularly shaped bodies, Sounded either by the sediments or by the Coast Range intrusives. In many instances the tuffs of the igneous masses grade into the sedimentary beds, and where bedded appear to be conformable. A good portion of these igneous rocks consist of augite porphyrites, there being numerous stocks as well as fragmental types of that com-position and also some flows. The "Copper Belt" which i s part of one of these igneous masses, consists of altered acidic felspar porphyry. It now consists largely of sericite,calcite and chlorite. It also has some tuffs, breccias and small amounts of tuffaceous sediments and the rocks.of the belt appear to be more sheared and altered than other rocks of the igneous masses. The rocks of the Copper Belt may be older than some of the adjacent crystalline rocks. It i s probable that over great parts of the area that vulcanism and sedimentation were con-temporaneous and that many volcanoes were submarine, i n the northern part of the area breccias and tuffs are common while flows and Intrusives are rather scarce© At the Premier Mine there is stock of orthoclase porphyry with s i l l - l i k e projections extending for several miles. It contains large inclusions of sheared tuffs and has been altered greatly to calcite, chlorite and sericite although the original texture is s t i l l evident. In some cases i t also has been sheared and i s then di f f i c u l t to dist i n -guish from some of the sheared green tuffs that occur nearby, although i t usually is lighter in color. It i s probably of the same age and origin as many other intrusives of the Hazelton group and was intruded before the batholith* 1 Hanson says, "The bodies of felspar porphyries and augite porphyrites apparently represent reservoirs, necks, and flows and the corresponding tuffs and breccias appear to be the products of craters now plugged by necks of crystalline rock*" There i s considerable similarity between the felspar porphyries and the augite porphyrites and although they have not been found to change from one to the other i n the f i e l d they possibly may have corne from a common magma® I f that is the case, the felspar porphyry probably represents a later differentiate from the magma and i s probably the younger of the two* A l l the western portion of the area, with the exception of some roof pendants i s underlain by rocks of the Coast Range batholith, which i n this area consists of massive granodiorite and quartz diorite* I t truncates the bedding planes of the sediments of the Hazelton Group in many places,* . Dykes are very numerous throughout the area, varying i n width from 1 inch to 100 yards or more and i n composition from gabbro to quartz porphyry. More dykes cut the sediments of the Hazelton Group than the igenous members of the Hazelton Group and there are s t i l l less cutting the Coast Range intrusives© Triere is one zone of dykes about lir miles wide i n which the amount of dyke rock i s greater than the amount of country rock* This zone starts i n the western part of the Salmon River d i s t r i c t and extends 1* Hanson, G* Memoir 175, p. 23 southeast towards the Cambria snowfield© Most of the dykes i n the zone are quartz diorites and are from 50 to 150 feet wide. Most of the dykes i n the area are probably related to the Coast Range intrusives but some appear to be related to some Tertiary lavas. There are some basaltic lavas a l i t t l e south of Alice Arm i n horizontal beds, up to a total thickness of 500 feet© They are believed to be Tertiary. ifS) Classification There i s a great variety of mineral deposits i n this area, most of them as yet only prospects© They are practically confined to members of the Hazelton Group, although some are found i n dyke rocks* 1 Hanson has described these deposits and also has classified them into 11 fa i r l y well defined types, 6 i n the Alice Arm area and 5 in the northern part of the area. In places they grade into one another and some of the types found i n the Alice Arm area have many similarities to some found i n the northern part of the area, so Hanson's classification lias, been modified to include only 7 types found either i n one or other of the areas or i n both. These are as follows: 1© Molybdenite deposits^ 2© Gold pyrrhotite deposits© 3© Copper deposits© 4© Quartz veins containing any of the following minerals, gold, silver, lead, zinc or copper. 5. Sphalerite deposits. 6. Quartz veins containing silver and lead© 7© Silver-barite-jasper deposits. These types w i l l now be dis-cussed, particularly those from which there has been any considerable production. 1© Hanson, G© Memoir 175, pp. 37-51 „ g 3 _ {4} Molybdenum Deposits Deposits of this type have been found only i n the southern pari of the Alice Arm area, and there are only two different occurrences so far reported. In both instances the molybdenum occurs i n small granite stocks and i n veins associated with these stocks* At the Lynn group, there is a small granitic stock and some quartz veinlets intruded into quartzite and a r g i l l i t e , and both the veinlets and the stock contain disseminated pyrite and molybdenite. There has been no production from this property. There has been some production from the deposit on the May-flower group and there is a small concentrating plant there but the deposit is not being worked at present. Here there is a series of parallel quartz veins, up to 10 feet in width i n a r g i l l i t e and a rg i l -laceous quartzite. The veins s tr ike north, and as they approach a granite stock, v/hich i s thought to have been their source, feldspar appears -and where they connect with the stock are albite dykes rather than veins® The minerals i n the veins i n order of their abundance* ares quartz, sphalerite, pyrite , arsenopyrite, galena, chalcopyrite, native s i lver and molybdenite® At depth, quartz and molybdenite only are found, the other sulphides were probably deposited i n the cooler zone closer to the surface. Locally the veins contain up to Zf0 molybdenite but as far as the veins have been explored they average less than that. The close association o f the molybdenite and the veins with small stocks is considered good evidence that these deposits were formed by mineralizing solutions that originated i n the same magma from which the stocks were formed. The fact that molybdenite is disseminated through 1. Dolmage, V. SH 1922, Pt .A, p . 31 the stock i n each case i s also indicative of a common origin for stocks and veins s j5). Gold Pyrrhotite deposits Only one deposit of this type is known. It occurs on the Salmon Gold group about 1 mile west of summit lake. There has been no production from this deposit. There i s one s i l i c i f i e d zone i n which there is much pyrrhotite and some arsenopyrite, sphalerite, galena and chalcopyrite and probably native gold, i n places i t i s 25 feet wide, but the average width i s less than 10 feet. . I t appears to have formed by replacement of augite por-phyri te 0 This main zone which strikes northwest i s joined by several westerly striking quartz veins which curve to the northwest as they enter the zone. These are narrower and contain much more quartz than does the main zone, and less pyrrhotite. A small stock of granodiorite is exposed about a mile north of the deposit and probably extends under the deposit and is Its source. (6) Copper Deposits a» Distributions Deposits i n which copper is the most important mineral are quite widespread throughout the area. In the Alice Arm area, copper veins, vein-like replacements and disseminations are common i n the Copper Belt and there are four localities in the northern part of the area In which copper deposits predominate either as veins or replacements, b. Description: The disseminated deposits are the least developed and the least promising* They have been farmed by mineralizing solutions —85— depositing pyrite, chalcopyrite and pyrrohite irregularly throughout large masses of fractured rock* Is yet no commercial ore body has been found, because the copper minerals are not sufficiently concentrated* A few of the vein and replacement deposits are in sediments but by far the greater number of them occur i n the volcanics of the Hazelton group, either in the highly sheared and altered Copper Belt or in shear zones* The veins consist of quartz with some chalcopyrite and pyrite although around the end of Portland Canal many of this type show a tendency to grade into veins more l i k e l y deposited at a lower temperature and containing other sulphides. Very few of the veins exceed 10 feet i n width, although they can often be traced over long distances. Some-times there i s very l i t t l e quartz gangu e and there i s so me inclusions of country rock. These ones probably represent transitions to the next type, the replacement deposits* In some of the replacements, quartz i s abundant but for the most part these are irregular zones i n which the copper minerals are more abundant than i n the surrounding rock. They often follow certain beds in the volcanic series, and while not so continuous as the veins are generally wider. Gold is generally less valuable in the replacement .deposits than i n the veins* Ore bodies of both the vein and replacement types have been developed but the production from them has not been large. c. Origin: The reason for the localization of the copper deposits is uncertain* At the end of Portland Canal there are 4 isolated -86-loca l i t ies i n which there are deposits of this type and they also occur in a long narrow belt called the Copper Belt. There do not appear to be any deposits s l ightly different from them near the Copper Belt nor any similar deposits between them and the contact of the batholith. Some of those near the end of Portland Canal show signs of grading into deposits in which lead and zinc are important. At f i r s t i t would appear as i f there were in this case 4 dist inct intrusives underlying this area from each of which there had been deposited copper deposits, and a l i t t ie further away lead and zinc deposits. However i t was no ted that a l l the typical deposits in these 4 areas are at lower elevations than the surrounding deposits i n which lead and zinc are important. It is then possible that the copper deposits a l l came from one source, and that they were deposited in a zone at some distance from the intrusive source and that lead and zinc deposits were deposited i n another zone beyond the f i r s t . I f then these zones had been truncated evenly by a level of erosion then the lead and zinc deposits would appear in a zone farther from the batholithic contact than those of the copper deposits. If , however, the deposits were truncated by a very uneven plane of erosion (and such i s the case) then some lead and zinc deposits might appear closer to the contact of the batholith than some other deposits, because the copper deposits might be exposed by deeper erosion beyond the zone of lead and zinc deposits. It appears highly probable that i n this case the great re l ie f , up to 4000 feet, makes possible the exposure of the copper zone i n 4 l oca l i t i e s . Irregularities on the surface of the intrusive mass would cause corresponding irregular-i t ies i n the mineralzones formed by solutions from the intrusive and so the zones may have been irregular . I f this i s the case then the -87-the mineralizing solutions that formed the copper deposits probably came from the Goast Range batholith. The occurrence of the copper deposits in the Copper Belt however is less easily explained by the zonal theory. There is a broad area intervening between the Copper Belt and the contact of the batho-l i t h i n which copper deposits do not occur* Nor are there any nearby deposits into which they appear to grade. Both of these facts would indicate that they are not related to the Coast Range intrusives exposed. On the other hand, they do occur in a zone which is very nearly paral le l to the main contact, and the mineralizing, solutions may have had easier access to this zone than to others because i t would appear to have been sheared more than adjacent rocks. This previous shearing may account for the local izat ion of the deposits at some distance from the ba tho l i th® Some inclusions of a r g i l l i t e i n intrusives of the Copper Belt are mineralized and Hanson thinks that this, along with the other evidence is Indicative that the intrusives of the Copper Belt were the source of the intrusives and that the mineralizing solutions did not come from the Coast Range intrusives* (7) Quartz veins containing one or more of the metals, gold, s i lver , lead, zinc or copper. a© Classif ication; Not a l l these metals are present in important quantities in any one of the veins included in this class. There real ly are distinct types within this class which however grade into one another. The minerals found i n the veins, generally indicate that these veins were formed In the deeper part of the mesothermal zone as defined -88-1 by Imdgren „ Variations included in this class are gold quartz, gold-silver, silver-lead, and silver-lead-zinc deposits* t>» Gold Quartz Veins? The gold quartz veins are found mostly near Georgia Biver and also on the Big Missouri group i n Salmon River d i s t r i c t . These veins are generally narrow,-in the case of the vein-lets on the Big Missouri they are generally just about an inch wide® They often carry considerable amounts of native gold. c. Big Missouri? Recently i t was announced that a concentrating plant capable of handling a large daily tonnage would be built to handle ore from the Big Missouri property. This decision, i s the result of the development of a large tonna ^e over a long period, "the group .being located originally i n 1904. While the deposits are not of the simple gold quartz type, the main gold values of the deposits appear to be due to this type of mineraliz ation, therefore this property w i l l be described here® 2 The deposits occur on Big Missouri ridge north of the Premier Mine in volcanics which strike north to north-northwest and are folded into an anticline. These volcanics are mostly fragmental and close to andesite i n composition. They have been extensively altered and now are generally green. There are numerous intrusions of felspar porphyry and some lamprophyre dykes. There are sheared, s i l i c i f i e d and mineralized zones i n these igneous rocks which strike north. These are lenticular and are often 1« .lindgren, W. Mineral Deposits, p. £10' 2. Hanson, G. Mem. 175, pp. 154-156. Minister of Mines Report 1934, pp B26-27 -89-very much elongated, the main zone having a length of 900 feet and widths of 300 feet. The zones are pyritized and sparsely mineralized with galena, chalcopyrite and sphalerite* In these zones are veinlets of calcite and quartz and also the youngest quartz veins which are short and narrow and which contain high gpld values. Low grade gold values are also found i n the s i l i c i f i e d zones outside of the veinlets, hut these values are generally -too low to be commercial. In some cases the mineralized zones are confined to one bed for a distance but do not continue in i t , their complete length. d« Gold Silver Veins; The gold silver deposits, the next members of this class are the most important so far discovered in the area. The ore deposits in the Premier Mine"*" are of this type* This has been the most important mine along the eastern contact zone and one of the most productive mines in British Columbia. Other deposits of this type occur near i t but they are generally of a lower grade. e. Premier Mine; The total production from this mine t i l l the end of 1934 equals 2,673,345 tons of ore averaging 0.52 oz. gold per ton and 12.99 oz. silver per ton. At this deposit the country rock i s a felspar porphyry which holds inclusions of sheared volcanic rocks altered to greenstones or green schists. The porphyry also lias been sheared and pyrite, sericite, and chlorite have been introducedc Fractures and shear zones are larger 1. Schofi eld, S. J . and Hanson, G. Mem. 132, pp. 50-58 1. Hanson, G« Memoir 175, pp. 162-166 1. Burton, V/. D. Economic Geology, Vol. 21, pp. 586-504 1. DoImage, V. C. M. J. Vol. 41-1920, pp. 454-458 and. more persistent where they cut the porphyry and less so when they cut the greenstones* The ore bodies were found i n these broken zones i the porphyry near i t s contacts with the intruded volcanics. The main ore zone which strikes northeast, has been mined along a length of 2000 feet and extends northward into the property of the 3. C, Silver Mines Ltd* I t i t s southern end i t turns west and then northwest but is not continuous in this direction or as rich, although i t extends for 3000 feet. Most of the ore bodies were above the 6th level, the grade of the ore decreasing from the surface to the bottom* Generally, the width of the ore bodies is less than 30 feet, although where the ore zone changes in direction the ore body was over 50 feet wide. In the main zone, the deposits near the surface dipped o o 70 northwest but flattened i n depth to dip 45 northwest. In some cas the strike length of the ore shoots was greater on the second and third levels than on those above or below this. The ore zone is irregular, without well defined walls, there having been some replacement of the wall rock by the vein materials. Where the zone passes through the greenstone tuffs i t more nearly resembles a f i l l e d vein, probably because the tuff did not fracture so readily under pressure* Metasomatism, caused by the mineralizing solutions and noticeable on both sides of the veins up to a distance of 100 feet, has caused the formation of pyrite, chlorite, quartz, sericite, apatite and calcite. The s i l i c i f i c a t i o n is most intense within 10 feet of the vein* Immediately adjacent to the veins are veinlets of quartz and aduiaria with some sericite and chlorite® -91-The following hypogene ore minerals have been recognized; pyrite sphalerite, galena, tetrahedrite, chalcopyrite, eleotrum, argentite, polybasite, pyrargerite and native s i lver* They occur as intimate inter-growths, the texture generally being coarser towards the surface, pyrite and sphalerite predominate at depth. Galena is not abundant but where i t does occur i t usually contains blebs of tetrahedrite, electrum and native s i lver , and the gold and s i lver values of the primary ore are probably in these minerals. Tetrahedrite i s quite common in the upper levels and frequently is the variety r i c h in s i lver called freiberfite*' The other hypogene ore minerals occur only in small quantities; generally being more important near the surface. Gangue minerals include apatite, adularia, quartz, chlorite, ser ic i te , ca lc i te , barite and albite . Of these quartz is by far the most abundant, although i n the upper levels calci te is very common. The others occur in small amounts only near the surface and in the adjacent wall rock. Burton l i s t s the following minerals as supergene i n this deposit, although some of them are also hypo gene; polybasite, chalcopyrite, native s i lver , argentite and covel l i te . The most important of these i s native s i lver which extends to greater depths than the others. It generally occurs as wires by i t se l f , often in vugs* Sometimes i t veins the supergene polybasite. Most of these minerals and the native s i lver i n particular, are found only near a system of fractures which represent re-opening of fissures formed at the beginning of the hypogene mineralization* These supergene minerals were deposited by meteoric waters circulating in the fissures and concentrating the soluble s i lver minerals from the parts of the veins since removed by erosion* - 9 2 -The minerals and values i n this mine have long "been the subject of controversy, some claiming that the s i lver values are largely due to the action of meteoric waters in producing the r i ch supergene s i lver minerals. Others claim that in this instance these silver minerals are hypogene and that the deposit has not been materially enriched by surface waters, The evidence furnished by the minerals in question does cot settle the point because both hypogene and supergene deposits are known in which these r i c h s i lver deposits are found. Favoring an or igin by surface waters for these minerals are the facts that these minerals are concentrated close to a system' of cross fissures in the deposit along which meteoric waters could circulate freely. de Also the rapid -increase in depth of these s i lver minerals and the s i lver values Indicates that the present ore shoots are connected i n origin with the present land surface. This connection would not be possible i f the deposits were wholly hypogene because they were formed many million years ago and the present land surface probably does not bear any relation to the former land surface. For the other point of view i t may be stated that freibergite (the s i lver - r i ch tetrahedrite) i s commonly considered to be hypogene and this mineral also decreases in depth. This decrease in freibergite would certainly cause a decrease in the primary s i lver values. The fact that the gold values also decrease in depth is also due to primary deposition because i t is not believed that there was a surface concentration of gold-bearing minerals. Also there is no increas e of copper values near the surface which might be expected i f the deposit owed its or igin to circulating surface waters. -93-It i s believed that the solutions depositing the hypogene minerals had their source in the magma from which the nearby granodiorite was formed. Other deposits of this type occur in the Salmon River d i s t r i c t but i t has been found that where they do not occur i n the poi*phyry they " are not of commercial value© • f© Silver-lead-zinc veins: With decrease i n the gold and s i lver values, and wi th a greater proportion of the base metal sulphides, the lead, zinc, copper deposits are found© Transitional between these are the silver-lead- zinc d e p o s i t s © Quartz veins of the la t ter type are found around the end of Alice Arm and also i n the Bear and Marmot River regions© These areas are widely separated and the intervening area has no similar deposits and they probably do not come direct ly from the same source© Those so far found in the Alice Arm area are confined to the a rg i l l i t e s and argillaceous q u a r t z i t e s © Commonly they persist only where they cross competent beds. Ore has been mined from the Esperanza, Silver Chord and Wolf groups, although the total production i s not high. They are narrow, often the best being less than three feet© Pyrite is the most abundant sulphide in the quartz gangue, sphalerite and galenaare less common. Those which have been mined contain some of the ruby silvers and argentite, Pyrrhotite, arsenopyrite, chalcopyrite and tetrahedrite also occur and some scheelite has been found at the Esperanza. In the northern part of the area, veins in which silver, lead and zinc are important are widespread and are found both i n the sedimentary and igneous members of the Hazel ton group. The veins are generally well defined and less than 6 feet i n width. Some of the veins, particularly - 9 6 -those i n the Portland Canal fissure zone have been traced over long distan-ces although the ore shoots in them are generally not very long. There has been considerable production from the Prosperity-Porter Idaho and Dunwell mines from veins of this type as well as other smaller properties. The Portland Canal fissure zone is the location for several deposits of this type. This zone is i n a r g i l l i t e s and is characterized by shearing faulting and para l le l mineral veins. The width is variable, up to 1500 feet and the length i s over 4 miles. It strikes at a small angle away from the strike of the a r g i l l i t e s , the strike varying from northeast to northwest. Dykes often preceded the replacement of the shear zones by quartz and sulphides and i t seems that in some way dykes guided the ore solutions and perhaps helped to keep them within definite channels. The ore shoots discovered i n veins i n this zone are a l l small and their, size seems to be direct ly proportional to the size of the containing veins. . Pyri te , galena and sphalerite i n a gangue of quartz and calcite is the most common mineralization. Occasionally chalcopyrite, tetrahedrite and barite are present to a considerable extent. With an increase in the amount of chalcopyrite, these deposits appear to grade into the copper deposits previously discussed. One of these the George Copper deposit has numerous veins in volcanics. The most abundant minerals i n the gangue of quartz jasper and barite are pyrite and chalcopyrite* Other minerals found local ly are hematite, magnetite and arsenopyrite. In the case of a l l these deposits, the source is believed to be underlying portions of the Coast Range intrusives. There probably were -95-two dist inct central sources, one to supply material for the Alice Arm di s t r i c t and the other to supply material for the northern part of the area. The variety of minerals formed in these deposits indicates that there was a considerable range of temperature during the formation of the deposits. Those in the Alice Arm d i s t r i c t may he related in origin to another small group, to be discussed later, which occur farther from the batholith. As regards the other area, Hanson"*' says, "that gold and copper are more p lent i fu l in the deposits of this group that occur near the batholith than i n those farther away, . . . . . there thus appears to be a zonal arrangement with respect to the edge of the batholi th." This indicates that in depth the lead s i lver veins would decrease in the value of their s i lver , lead and zinc but gold and copper would probably increase. (8) Sphalerite Deposits a.General Considerations: Deposits in which sphalerite i s pract ical ly the only mineral are found only on McGrath Mountain, three and four miles from the end of Al ice Arm. Bone of the deposits have been developed to the stage where ore bodies are blocked out, nor has there been aby production. Exploration has shown masses of considerable size, but their continuity has not been proven. A l l the deposits occur near the edge of a stock of augite. porphyrite, in sediments which are sometimes inclusia&s in the stock. They vary much i n form, some approaching veins and others being only irregular replacements. Occasionally the sphalerite is found cementing brecciated zones. Single exposures up to 20 feet are known. Development 1. Hanson, G. Memoir 175, G.S.C. p. 46. -96-work so far suggests that the deposits farthest from the stock may be more persistent but smaller than those immediately beside the periphery of the stock. Quartz and calcite are the gangue minerals; sphalerite is practically the only sulphide. b a Origins The mineralization and location of these deposits separates them from any other in the area. Their position in regard to the stock and the fact that what appear to be inclusions in the stock are also mineralized leads to the conclusion that the augite porphyrite was the source of the mineralizing solutions. It i s possible that fissures may have formed during some regional movement in the v i c i n i t y of the stock and these fissures later became the locus from mineralizing solutions. This interpretation of the origin appears to be less probable than the other i f the deposits were formed after the consolidation of the augite porphyri te stock and came from the same magma from which the stock was formed, then they are Jurassic and older than the majority of mineral deposits in the area. 9a. Quartz veins containing silver lead and zinc. These veins, which probably are related in origin to another . group previously described, are put in a class by themselves because they occur in a single zone of shearing and are some distance from any similar deposits. They are found in the bottom of upper Illians Biver valley„ There has been a small production from some of them* A l l the deposits occur within a shear zone which i s parallel to Illiance Biver and they a l l strike north and south parallel to the zone. They consist of gashes and lenticular veins of quartz* The rocks of the shear zone in which they occur have "been greatly altered and are now soft, white and f i s s i l e . The veins which contain any considerable proportion of sulphides are generally less than 5 feet wide and mineralized with pyrite , sphalerite galena and t e t r a h e d r i t e © Chalcopyrite and chalcocite have been found i n some of them. Si lver is associated with the tetrahedrite and where there is much of i t , then the veins are high grade s i lver ores. Hanson assumes that the source of the mineralizing solutions was an underlying part of the Coast Range batholith. Pre-mineral shearing of the shear zone probably permitted the solutions to escape easily along the shear zone and so the shearing would cause a concentration of the deposits. The s imilar i ty of the deposits to deposits of somewhat the same type at the end of Al ice Arm indicate that their source may have been the same. 10. Silver-Barite-Jasper deposits* a. Occurrences This last type of deposit is quite dis t inct ive ; the deposits in i t generally do not appear to grade into different types, and they are a l l found wi thin rather a restricted area, 6 miles load and 1 mile wide, east of the Copper Belt. There has been a larger production from deposits of this type than from that of any others in Alice Arm. A l l the deposi ts occur in f e l s i t i c rocks, most of which were intrusive rather than extrusive. The deposits are replacement veins, wider than most veins, commonly from 10 to 15 feet wide and sometimes reach a width of 75 feet. They Were formed by replacement and f i l l i n g of brecciated and crushed zones. b. Mineralogy: The most common gangue mineral i s quartz, but calcite , -98-barite and jasper are common also and i n some veins some one of these minerals is more abundant than the quartz. Pyrite , galena, sphalerite and tetrahedrite are the most common ore minerals. Others which have been found in some of these veins include chalcopyrite, argentite, pyrangerite, proustite, /3earcite and native s i lver . Generally there are only minor amounts of the r ich s i lver minerals unless there has been some secondary enrichment, therefore these veins have seldom been developed unless this enrichment has taken place. The Dolly Varden1 i s an instance of this . At this mine values are exceptionally high for a depth of nearly 200 feet below the surface, below which they rapidly decreased. Also the values were higher near the numerous post-primary mineralization faults cutting the vein which permit of circulation of surface waters. Other veins of this type are known to contain high grade s i lver minerals near the surface but to what depth they extend is not known. It seems clear however, that there was some enrich-meut i n pre-Pleistocene times, which was not removed by glacia l action. c . Origin: Deposits that contain orpiment and realgar have been found north of the zone i n which these deposits have been found and as these minerals generally are deposited only at low temperatures i t is probable that they were deposited by cooler solutions from the same source. Also in these deposits the galena and sphalerite are finer grained indicative of a quicker rate of cooling during their formation. This presence of minerals to the north indicative of a cooler temperature of deposition makes i t appear probable that the source of the mineral-bearing solutions was to the south of the s i lver barite-jasper veins. The isolated position of deposits of this type, and their occur-1. Hanson, G. C.I.M.M. Trans, v o l . 25, pp. 212-224 -99-rence i n intrusive rooks, leads Hanson to believe that they were deposited by solutions which had their source i n the magma from which these Hazelton group intrusives formed* At any rate, their relation to nearby mineral deposits does not clearly indicate that they were formed by the same series of mineralising solutions which formed other deposits c I f formed by solutions emanating from the Hazelton group intrusives, they are probably somewhat older than most of the deposits genetically associated with the Coast Range i n t r u s i v e s ® The diversity of the mineralization found i n the Portland Canal area is encouraging from the point of view of future development because the great proportion of an already large production is from only a few' mines. 1 Alice Arm-Skeena River Immediately south of the Portland Canal area, between Alice Arm and Skeena River there is an extensive length along the contact from which there has been no production from lode mines. Mineralization i s not altogether lacking, but i t i s less abundant than a large portion of the contact area and there has been very l i t t l e development work done. Those deposits which have been discovered l i e between the Haas River and Zitsumgallum lake. The deposits which have been described are chiefly narrow quartz veins, with values chiefly in gold or gold and silver, and occur in sediments. The Si lver Dollar is 12 miles north of Rosswood and has not been sufficiently developed to reveal i t s true character. There are small shoots of high grade s i lver ore, of which tetrahedrite is the principal mineral, in a r g i l l i t e * 1. Hanson, G. SR 1922, Pt .A, pp. 35-50$ SR 1923, Pt . A. pp 29-45 -100-Eight miles northeast of Cedar River Crossing on Egan Creek is the Relief group. Other claims nearby are the Blue Grouse and Hunter. A quarts vein up to 8 feet wide, cutting a r g i l l i t e and granitic dykes lias "been traced for a 1000 feet. The other minerals in the vein include calcite and along a width of 3 feet from the foot-wall, chalcopyrite and galena© A deposit somewhat similar to the last one, occurs on the Sunlight claim 4 miles east of Rosswood, although on this claim the vein varies from 2 to 12 feet in width and i t is spl i t up into smaller veins i n several places. The mineralization consists of pyrite, galena and sphalerite in the quartz gangue. There has "been quite a few claims staked on the slope of Maroon Mountain 5 miles east of- Kitsumgallum Lake. Here the veins are paral le l to the bedding of argillaceous quartzite in which they are. These veins- appear to be confined to a single zone in the quartzite, about 100 feet below a 50 foot bed of conglomerate. There are a few veins '. - 1 exposed in that posit ion relative to the conglomerate over a large area . The quartz of the veins is often stained and has been honeycombed by oxidation of sulphides. The.chief values are i n gold. On the east side of Kitsumgallum Lake there is an ore zone i n a quartz-sericite schist, which is paral le l to the shearing planes of the enclosing rock. Quite high values in gold and si lver are found but the extent of the zone has not been determined. West of Kitsumgallum Lake, near the south end, there is a narrow quartz vein in a r g i l l i t e , near a large granodiorite dyke. It is only a foot wide, but has been reported to carry up to 12 ounces per ton 1. Hanson, G. S.R. 1925, P t . A. pp 100-119 - 1 0 1 -of free golds Zymoetz River Area (See Figure 4)  (a) General Considerations t A few miles above the mouth of Zitsumgallum River, Zymoetz River flows into the Skeena. The area drained by the Zymoetz i s also part of the contact margin area, and while not an area from which there has been a large production, nevertheless, there has been some. There are many prospects and interest in some of these has been rather keen i n the last few years. The properties for the most part are small and highgrade, a l -though some of the copper deposits may be of considerable size. :(hj Mineral Zones Along this section of the contact there are numerous stocks near the contact, and often these are mineralized but Hanson i s of the opinion that these are only good host rocks and that the mineralizing solutions came from the main body of the batholith. He* recognizes 3 zones, an inner zone that includes some of the batholiths margin, 7 miles wide in which tungsten, molybdenite, gold and goId-copper ores are found. Outside of this , a zone 6 miles wide in which copper is the most valuable product of the ores. The outermost zone is less well defined than the two inner zones,' and is distinguishable because the chief values are in s i l v e r , (c) Inner Zone The inner zone, the one nearest the source of the mineralizing solutions, includes a tongue of the batholith that extends northeast from the main mass. It trends northwest para l le l to the general trend of the contact. 1 On the southwesterly side of this zone are deposits of scheelite, molybdenite and gold in quartz veins, accompanied by pyrite, 1. Hanson, G. Proceed. R.S.C. 1927, pp. 119-21 -102-chaleopyrite and pyrrhotite. In the northeastern portion of this zone copper becomes more abundant and bornite i s an important mineral. There are about 25 deposits in this zone whose minerals indicate the high temperature at which they probably were deposited. The highest temperature deposits are found in the granodiorite on Thornhill Ridge, south of Zymoetz River. The scheelite occurs as lumps up to 3" in diameter sporadically distributed throughout a pegma-t i t i c quartz ve in . This vein, which varies from 6 inches to 2 feet in width has been traced for over 200 feet. Other minerals i n It include pyrite, chalcopyrite, galena, sphalerite, native gold, barite and feldspar, A mile south of the scheelite deposi t, there is a large oval area 100 feet by 200 feet in which there are numerous rusty patches and some pegmatite dykes. This area occurs in fine-grained granite. The rusty patches are the oxidized outer parts of nodular areas of coarsely -crystal l ized minerals, the outer part of which contains pyri te . Minerals in the nodules include muscovite, yellow mica, muscovite pseudoraorphic -after tourmaline, c l inoyois i te , quartz and nodules of molybdenite. These nodules of molybdenite are radical ly laminated and are up to 2 inches in diameter. Contact metamorphic replacement of limestone by chalcopyrite, magnetite, garnet, epidote, tremolite, quartz and calcite have been reported to occur south of the Zymoetz River also. Hear the scheelite deposit, which is located in the Ptarmigan group is an aplite dyke, on both walls of which are quartz veins. Along the eastern end of the dyke the foot-wall vein is the better and carries pyri te , chalcopyrite, galena, sphalerite and free gold. Further west the mineralization is similar but the best values are obtained from the -103-hanging-wall vein® Hear Usk are some of the veins i n which hornite i s important and copper "becomes of importance. Gold is also present in these veins. The Cordil lera group is 1 mile from Usk on the west side of the Skeena. There are numerous veins on this property up to 6 feet wide, para l l e l to the strike of the intruded rocks. The quartz i s mineralized with borni te, chalcocite and free gold. About 4 miles south of Usk, i s the Columnaris Mine which has produced intermittently in the past. On this property there are nine para l le l quartz veins, from 1 to 3 feet wide, occasionally up to 6 feet wide, about 150 feet apart. They strike north-northwest and dip northeast, i n altered andesite. Pyrite , chalcopyrite and galena are the important sulphides, although the ore is valuable pract ica l ly only for i t s gold. There is a l i t t l e s i lver . Only 4 of the veins have been explored and some ore shoots have been developed in 3 of these. The veins have been faulted, not a l l at the same time or in same d irect ion. (A) Second Zone The second zone, that in which copper is the most important metal, i s best shown by some of the deposits on Kleanjra, Chimdemash and St. Croix Creeks. In this zone, the important minerals are chalcopyrite, bornite and chalcocite, gold and si lver values are generally very low© In this zone there have been recognized three shear zones i n which the minerals are impregnated irregularly and about 20 veins in which the copper minerals predominate. At one property, the Horth Star group, a bed of limestone seems to have been replaced by garnetite and s l ightly mineralized. An example of these isfound on the Banner Homestake group. -104-This property i s on the south side o f Chimdesash Creek, 11 miles from Usk. The shear zone up to 2 0 feet in width, and over a 1000 feet long, occurs in volcanic "breccias and lava flows cut by green dykes» Chalcopyrite and bornite are scattered throughout the zone and there are also some secondary copper s t a i n s © In some cases these shear zones contain stringers of quartz, calcite , chalcopyrite, chalcocite and bornite. One of this type occurs on the Peerless group near the head o f KLeauza Creek. Here the shear zone contains many quartz-calcits veinlets, each up to one foot in width. Garnet, epidote, hornblende, tremolite, and jasper have formed in the shear zone in the sides of the veins, indicating that the deposit was formed at f a i r l y high temperature. Northeast of these copper deposits l ies the s i lver zone, which however is not so well defined, the deposits merely occurring farther from the batholith than those previously described. In some of these there is some copper and lead, in addition to the s i lver , but there i s generally no gold. These deposits are located at the heads of Legate and Chimdemash Creeks. About 25 veins have been discovered i n this area which is roughly equidimensional. The chief ore minerals in these veins are galena, sphalerite, tetrahedrite, chalcopyrite, pyrite, bornite and chalcocite. The veins do not seem to be affected by the country rock, being equally plent i ful in andesite or breccia or d ior i te . One of these properties that has considerable promise is the M. and M. group on the east fork of Legate creek. Here there are three veins cutting a diorite stock. Two, each about 4 feet wide, in addition to the sulphides, also contain native s i l ver . The larger vein i s in a shear zone and spl i t s into two, but at the junction is over 20 feet wide© -105-0n the White Bear and South Fork claims on the South fork of Legate Creek, there is a vein which contains "besides the usual sulphides, some scheelite, and some native s i lver , The ore minerals so far have only been found in small pockets, the largest so far found being 20 feet . long and 2-g- feet wide. At the head of Chimdemash Creek, i s Si lver basin i n which two sets of veins have been found, some in volcanics and the others i n a diorite stock. One set strikes northeast and the other southeas t© The best showing found occurs at an intersection of two of these veins© Most of them are narrow, but are high grade and contain native s i l ver . Hazel ton" (a) general Considerations East of the batholith and south of the Skeena River are two areas of interest from both of which there has been some production. In both of these areas the source of the minerals i s believed to be a stock, the relationship of which to the Coast Range intrusives i s uncer ta in© The more northerly of these is just south of Hazelton at the confluence of the Bulkley and Skeena Rivers© 1MB area can also be considered as consisting of two dist inctive areas. One, north of the Bulkley River is marked by the occurrence of veins in tuffaceous sediments at some distance from the contact of a large intrusive© These veins characteristically are valued for their s i lver lead content© South of the Bulkley River the deposits are i n or near a large stock of granodiorite and are characterized by the presence of copper, gold and some s i lver . Molybdenite and wolframite also occur in deposits of this area. Some of the ore south of the Bulkley occurs in veins but many of 1. O 'Nei l l , J. J . Memoir 110, G.S.C. pp. 6-35, 1919. -106-tiiese veins change into shear zone replacements along their strikes (b) Si lver head Deposits Among those properties north of the Bulkley River are the Si lver Standard, and American Boy, from which there has been some produc-tion, and several small prospects. Veins on these properties are characterised by galena, sphalerite and tetrahedrite that approaches freiberyite. Other properties have considerable amounts of jaaLesonite, as well as the other sulphides. The Si lver Standard, the most important, has 9 veins, only two of which have been developed. Other minerals found i n some of these veins are pyrite , arsenopyrite, s iderite , pyrrho t i te, chalcopyrite, and jsjrf.eson.ite. Most of the production has come from the Main vein, and i t is noticeable in i t that the zinc and lead values decrease i n depth. The ore shoots are narrow, generally less than 4 feet, although i n places they widen to 8 feet . Often calc i te i s almost as abundant as the quartz. Often the mineralization is intensified near small cross fissures which are also mineralized. Two miles east of the Silver Standard is the American Boy. There are three veins, the widest being three feet, cutting members of the Hazelton group, and their mineralization is very similar to that of the s i lver Standard veins. (c) Copper Sold Deposits There has been a greater production from the properties south of the Bulkley River. These include the Rocher De Boule, Delta, Hazelton View, Cap and Golden Wonder properties. Rocher de Boule: Of these the Rocher De Boule has been the most -107-important. There are five veins on this property, of which 2 are richer than the others, and were formed by the f i l l i n g and replacement of fissures and brecciated zones. The veins strike almost at right angles to the contact of the stock, near the edge of which they are located. Values i n the veins vary greatly often there being barren lengths between the ore shoots. O'Neil l considers that the two periods of fissuring which he recognizes,were of great importance i n controlling the formation of ore shoots. He believes that the f i r s t fissures i n some places shattered considerable widths of rock and i n others made clean cut breaks. When these fissure zones were f i l l e d and replaced wi th quartz, a lot of act inol i te also developed and the result was some very wide portions con-taining fragments of country rock cemented by quartz and act inol i te and other narrow portions consisting of quartz and act inol i te . The secondary fissuring which preceded the ore-bearing solutions, emphasized the differences along the vein. Where the vein was wide and heterogeneous, i t was easily shattered and thus the ore bearing solutions had easier access to these parts of the vein and also because the fragments of country rock and actinolite were more easily replaced than the quartz, there was a greater deposition of the ore minerals at these positions of shattering. Where the original vein was narrow and homogeneous, the second fissuring made a clean break and there was less chance for the mineralizing solutions to replace the vein and rock. At these places, the veins are generally narrow and low grade. - Copper is the most important metal in these veins, although s i lver and gold are also valuable. The minerals present are chalcopyrite, pyrite, pyrrhotite, arsenopyrite, tetrahedrite, sphalerite, galena, -108-raagnetite and molybdenite© Hornblende, glassy and milky quarts are the most abundant gangue minerals. Others present include calcite , siderite and tourmaline. Hearer the center of the same granodiorite stock is the Delta property, of which some of the fissures are believed to be extensions from the Hocher De Boule. Its mineralization i s similar to that of the Hocher De Boule, although there is a greater proportion of minerals indicative of a high temperature, which is to be expected, because this deposit i s closer to the source. The history of the formation of the deposits i s thought to be the same. . Magnetite is the most abundant of the metallic minerals and is accompanied by some specularite. There are also some traces of t i n i n the ore. At the Hazelton View, molybdenite i s the most imp ortant mineral, i n places there being good widths, averaging 3 or 4$ molybdenite. At the Black Prince deposit there is some wolframite, otherwise the mineralogy is the the same as the others. There are numerous other deposits i n and near the stock but in general they are closely similar to those already described. It is quite evident that the minerals were deposited i n zones, and that the source was the magma from which the stock formed. Those deposits outside the stock usually contain good amounts of s i lver , lead and z inc . Those in the stock are valuable for their copper and gold and also contain some molybdenum, tungsten1 or tin® 2 Hudson Bay Mountain . (See Figure 4) (a) General Considerations i « . Hurst, M* E© S.H. 1924, P W . © pp. 44-46. 2c Lay, D. Lode-Gold Deposits of B.C. Bull #1-1932, pp. 42-54 and Jones, R.H.B. SR 1925, Pt .A, pp. 120-143 -109-South of Hazelton and about 25 miles east of the main contact of the Coast Range intrusives is the second mineralized area of some importance which is believed to be genetically connected to a stock* r Hudson Bay Mountain i s an isolated mass, west of Smithers on the Bulkley Biver . The greater part of the mountain i s composed of members of the• Hazelton group and of the Skeena formation, both of which have been thought to be domed by the intrusion of granodiorite and dior i te . Small masses of these intrusives are exposed near the center of the mountain. There also has been some over thrusting and block fault ing. ' :• There has been a small production from several properties on this mountain, most of which are on the southwestern slope. The Henderson or Duthie mine having produced over $1,200,000 i n gold, s i lver , lead and z inc . (b) Occurrences Mineralization i s most common i n paral le l shear zones in andesite or rhyolite. In a few cases^stocks of granodiorite have been mineralized, in one case a bed of conglomerate and i n another a limestone bed has been replaced. The deposits in the shear zones have formed by a combination of f i l l i n g and replacement. A good deal of brecciation accompanied the shearing and the particles are partly replaced and partly cemented by the vein-forming materials. (c) Fissure System The fissures in which the ore occurs form 2 fa i r ly irregular systems, nearly at right angles to each other. One, in which the fissures strike approximately northeast, i s developed on the western slope of the mountain, on the Henderson, King, Tut, Coronado, Mamie and Victory •-110-properties, and on the northern slope of the mountain on the Silver Creek, Rio Aspen and White Heather properties. The other system, str iking northwest i s developed on the eastern slope on the Empire, Dor-othy, Yukon and Canadian Citizen properties. In some cases the veins do not appear to belong to either system but these are exceptions. Not a l l of the shear zones are mineralized?, In many of the veins there has been some movement since the mineralization for the ore minerals are brecciated and the galena is oftei g n e i s s i c ® In one instance on the Si lver Creek, and possibly others, mineralization has followed this movement and quartz, calcite and chalcopyrite have been introduced* fd) Wall Rock Alteration Alteration of the wail rock adjacent to the veins i s con-spicuous. In outward appearance, the country rock has been bleached for a distance up to 10 feet from the wall of the vein* The changes which have been caused at the time of mineralization by the hydrothermal solutions- consist of ser ic i t izat iou, prophylitization and s i l i f i c a t ion * In appearance the altered rock looks l ike a fine-grained rhyolite* The alteration increases i n intensity towards the vein* (e) Zoning A zonal distribution of the ore minerals is evident, the higher temperature minerals being closer to the center of the mountain and the lower temperature minerals being farther away, indicating that the focal point is somewhere in the interior of the stock of granodiorite. This zonal distr ibution of minerals combined with the effect of doming and then erosion causes the rather anomalous result of higher temperature deposits being found at greater altitudes than lower temperature deposits. - I l l -Shis has resulted from the removal of the lower temperature deposits and their enclosing country rock from the upper part of the mountain by erosion. .(See Figure 4.) The types shown on the western slope of the mountain include, nearest the interior, pyrrhotite-sphalerite, then sphalerite-chalcopyrite and, farthest from the interior, galena-sphalerite deposits. (f] Mineralization There is considerable variation in the types of deposit but i n general the lead and zinc content of the ores i s valuable and gold is more valuable i n the high temperature deposits and silver i n the lower temperature deposits. Ore minerals that have been identified include galena, sphalerite, pyrrhotite, chalcopyrite, pyrite, tetrahedrite, magnetite, arsenopyrite, bornite, chalcocite, covellite, native silver and ruby silver, and the gangue minerals, quartz, calcite and siderite* fg) Puthie The most productive mine up t i l l now is the Duthie, formerly called the Henderson. There has been a total production i n the neighbor-hood of .J»I,200,000 from i t , from silver, lead and zinc in that order, and small quantities of gold. The average tenour of the ore from this mine being gold 0»02 os. per ton; silver 37.2 oz per ton; lead 4.8 '4>% zinc 5.2^. Lay and Jones are of the opinion that some of the silver values are from secondary silver minerals* There are two converging veins on this property, striking northeasterly and dipping away from each other. Of these the Henderson, the more southerly, i s the more important, although the intersection also is important. There are a few other veins, with lower values* The numerous other properti es on the mountain have not been -112-so extensively developed and there has been very l i t t l e production from most of them. The occurrences are similar in general to those already described, either the values being lower or the ore bodies smaller than those of the Buthie property* 1 Skeena River-Eutsuk Lake  (all General Considerations Returning again to the main batholithic contact, and proceeding south from Skeena River, there is a long section which is re lat ively inaccessible. The small amount of prospecting that has been done has shown that there is considerable mineralization, but as yet there lias been no production nor very l i t t l e development. The d i f f i cu l ty of transporting material to the prospects along the contact being great, inasmuch as the contact here is well within the Coast Range. Both Brock and Marshall were favorably impressed wi th the extent and diversity of the m i n e r a l i z a t i o n ® Brock decided that in the v i c i n i t y o f Eutsuk Lake the tuffs of the Hazelton group were the most easily replaced and susceptible to mineralization* Further north and west, Marshall concluded that waterlain members of the Hazelton group appeared to carry the greatest amount of 2 mineralization. Marshall also said that "The numerous dykes and stocks associated wi th the Coast Range batholith are invariably mineralized with pyrite chalcopyrite, galena, sphalerite, arsenopyrite and i n places bornite." The main contact also along this section is generally mineralized with similar sulphides, although i n most cases no work has been done on the outcrop. , 1. Marshall, J . R. SR 1929,Pt.A,pp.52-58: SR 1925,pt.A,ppcl52-4:SRl926,pt.A, pp.39-44 1. Brock, R.W. SR 1920, Pt .A, pp. 91-94 2. Marshall, J . R. SR 1925, Pt .A, pp. 153 -115-(b) Occurrences Near LakeIse Lake, most of the deposits that have been described can probably be considered as having been formed at high temperatures© Those on the east slope of Thornhill ridge, including some molybdenum and tungsten deposits, have been described above. On the west slope of Thorn-h i l l ridge is the Golden Nib property. On this group, there is a shear zone about 50 feet wide i n porphyritic granite which i n turn passes into granite, being only 200 feet wide. Fractures i n the shear zone are f i l l e d with quartz mineralized with pyrite and chalcopyrite. These veins are very irregular both as to size and mineral content. They may be 2 feet in diameter and then break up into a number of stringers less than 2 inches in width. The pyrite which is in the veins and also to some extent in the country rock, is auriferous, running i n some cases about 3 ounces gold per ton. There has been a small shipment from this group. South of the Golden Nib group, on the same slope, i s the Beaver group, where there is a shear zone, up to 150 feet wide in quartz d ior i te . Quartz veinlets i n this shear carry hematite and pyrite and the gold values are quite high. On the ether ridge on the other side of Williams Greek are several roof pendants i n the granite. Along their contacts, there are contact metamorphic deposits containing magnetite and chalcopyrite. These are concentrated near the coutact of limestone members of the pendants with the intrusives. Pyrite, epidote and iron garnets are also abundant in these deposits. In some cases these contact deposits occur along the contact of aUd dykes which are younger than the mass of intrusives. In the section between Tahtsa and Eutsuk Lake there are several mineralized zones, most important of which are those on Sweeny and -114-Ghikamin. mountains© In these zones, s i lver and lead are the valuable minerals and these deposits were probably formed at medium temperatures© Sweeny Mountain i s about 6 miles northeast of the east end of r Tahtsa Lake. The deposits so far discovered on i t are found i n bo th the sedimentary and volcanic members of the Hazelton group. The Emerald group, the most important prospect on the Mountain, was discovered i n 1916. On this property there i s a shear zone parallel to beds of tuffs and a r g i l l i t e s . The tuffs are now sheared, altered and stained, the fractures i n the tuffs being f i l l e d with quartz. These quartz veinlets have been intensely fractured since their formation and galena and subordinate amounts of pyrite chalcopyrite and sphalerite now f i l l these fractures, pyrite and chalcopyrite are also disseminated through the wall rock. The shear zone is about 20 feet wide and over the greater part of i t s length less than 10 feet is mineralized. Of this width, only about 30 per cent consists of ore minerals, the remaining 70 per cent being gangue and country rock. In some cases there are lenses of so l id galena 8 to 10 inches wide, but these are discontinuous and usually very short. Further, along its strike the mineralization is confined to a 2 foot vein, the total length of the deposit being 2000 feet© The galena carries only a trace of gold but has about 70 ounces of s i lver per ton. About a -|- mile east of the Emerald deposit is the Glacial* deposit on which there is a quartz vein up to 3 feet wide in a sheared zone i n porphyritic andesite. The maximum width of the shear is about 10 feet and the average is about 6. Mineralization is similar to that on the Emerald group, the galena lenses however, being confined to the hanging-wall of the vein and the galena carrying less s i lver . -115-Southeast of these tvx> deposits, on the same mountain, are the Sunset mineral claims. The deposits are s imilar . The quartz veinlets in fractured porphyritic andesites are mineralized with pyrite , marcasite, chalcopyrite, arsenopyrite, galena and a l i t t l e sphalerite and hematite. Gold is more important in these veins, the arsenopyrite running about 3 ounces to the ton, although the galena is argentiferous. On the south shore of Whitesail Lake, about 17 miles from its outlet, there are several groups of claims. The Cariboo group of claims is located in a series of folded and fractured tuffs. Veinlets of quartz and calc i te have f i l l e d these fractures, some of them being 15 Inches wide. In these veinlets are lenses of sphalerite, galena, pyrite , chalcopyrite, and arsenopyrite, some of these lenses being several feet in length. Assays of these zones have shown that gold and s i lver are low, although lead and zinc might be quite high over mining width. There are several groups of claims on Chikamin Mountain which is on the ridge between the western ends of Whitesail and Eutsuk Lakes. The Si lver Tip claims are on the northwest slope, 1-J- miles from the shore of Whitesail Lake. The deposit occurs i n a well bedded tuff which has been strongly sheared. In this tuff are veins of quartz mineral-ized with galena, sphalerite, pyrite and a l i t t l e chalcopyrite. In some veins the gangue consists of calcite and talcy gouge. The total width of the mineralized zone is 7 feet, of which about 40^ may consist of mineralized veins. The percentage of sulphides to gangue is quite high, there being several veinlets- composed entirely of sulphides. Gold values are low, but the galena carries high s i lver values, some assays running over 100 ounces of s i lver per ton. -116-About a mile southeast of the Silver Tip is the Nickel plate mineral claim. On this claim there is a well defined vein exposed, para l le l to the bedded tuffs i t cuts* These tuffs have been s i l i c i f i e d and are now glassy, very hard and break with a conchoidal fracture* This vein is continuous southwards for a half a mile, and is exposed at the top of Chikamin Mountain over 1700 feet higher* Along this length i t i s continuously mineralized and averages 15 inches i n width. Fractures i n the quartz contain galena, sphalerite, chalcopyrite and pyrite , and these fractures being more or less paral le l to the trend of the vein and often very thin, give the vein a banded appearance. Some of these fractures contain lenses of sol id sulphides 2 inches wide and up to 10 feet long. At the lower elevations, the galena and sphalerite are present in almost equal amounts and at higher altitudes there is pract ical ly no sphalerite. Gold values are low and the s i lver values i n the galena are very errat ic . East of this vein porphyritic andesite i s intruded by numerous narrow dykes of porphyritic d ior i te . Gutting both the andesite and the dykes are narrow quartz-calcite veins up to 6 inches wide. They contain chalcopyrite and pyrite , which are auriferous* South of these veinlets, there is a zone 20 feet wide along the contact of one of these dykes wi th the andesite. It consists of alternating bands of iron ore up to 8 inches wide and andesite up to 3 feet wide. Crystals of andradite garnet and epidote are abundant i n the iron bands, which consist of magnetite, which is almost led est one. Bella Coola-Gun Creek^" (a] General There is a section along, the batholithic contact on the east 1. Dolmage, V. SR 1928, Pt .A , pp. 87-93* SR 1924, Pt .A, pp. 68-75$ SR 1925, Pt .A, pp. 162-163 -117-between Eutsuk Lake and Bella Goola which has not been geologically mapped and which has not been thoroughly prospected. There has been no mineral production from it® South of that section, there is another long section which has not been thoroughly prospected, and which has been mapped. There are quite a few promising prospects in i t , some of them being developed at present, most of them being in the southern part of the section. The fact that some parts of the contact are covered by post-batholithic rocks, i n part accounts for the lack of prospects along this sections the other reason being the relat ive inaccessibil ity of the contact area, (b) North of Tat la Lake In that portion of the section, north of Tatla Lake, there are only two deposits described. One of these is an auriferous arsenopyrite deposit 2 miles north of Perkins Peak, which is about 17 miles west of the end of Tatla Lake, The deposit consists of mineralized quartz veins or s i l i c i f i e d zones in a series of sedimentary rocks composed of black a r g i l l i t e s , argillaceous sandstones, cherty conglomerate and volcanic breccia. The s i l i c i f i e d zones from 10 to 20 feet wide are sparsely disseminated with arsenopyrite. In one zone there are 6 narrow veins of sol id arsenopyrite over a total width of 3§- feet. Gold seems to be present in a l l the arsenopyrite, but only in small quantities and no commercial shoots have been developed. A mile southeast of Perkins Peak is a deposit of pure hematite replacing a bed of tuff. It is cut by veins of quartz and specularite and many adjacent beds have been pyr i t ized . The deposit is very pure but i t is re lat ively small and has no present commercial value. -118- -At numerous places near the contact there are pyrit ized zones which have not been carefully prospected or sampled and which might be auriferous, 'f (G) South of Tatla Lake South of Tatla lake, along the contact, mineralization seems to have been more intensive, the Triassic rocks in particular, being impregnated with pyrite and pyrrhotite. In some cases these mineralized zones carry some gold values. West and south of Franklin Arm of Ghilko lake there are a few small contact metamorphic deposits containing copper in limestone beds near intrusions . (d) Feeav The Feeny property is 10 miles northwest'of the southern end of Tatlayoeo lake. On this property, quartz veins mineralized with arsenopyrite and pyrite carrying values in gold and s i lver cut highly altered sediments. These sediments, which were a r g i l l i t e s and quartzites are probably part of a roof pendant in a d io r i t i c phase of the batholith. Ho commercial ore shoots have been discovered yet, although in some cases there are some fa ir gold assays. (e) Bridge Island Four miles southeast of the southern end of Tatlayoeo lake is the Morris property, now called Bridge Island Gold Mines l t d . There are three quartz veins, varying from 8 inches to 8 feet i n width, striking almost north. They cut arg i l l i te s and fine sandstones just a few 100 feet from a stock of quartz d ior i te . Disseminated fa i r ly evenly through the quartz of these veins is arsenopyrite, pyrite, stibnite and two or -119-three unidentified minerals, which are probably silver bearing© These •unidentified minerals are closely associated with the stibnite and occur towards the central parts of the veins, while the arsenopyrite and the pyrite tend to occur-along the walls of the vein© The adjacent wall rocks have been altered u n t i l they now resemble a dense grey green chert. Assays have shown that the gold i s associated with the arsenopyrite and the silver with the stibnite© One ore-shoot has been developed 150 feet long, about 2 feet wide and averaging about 0©55 ounces gold per ton and about 8.5 ounces silver per ton, but i t has not been exploited as yet© (f) Taylor Windfall Another small gold hearing deposit i s located on Battlement Greek a -§• mile above i t s junction with the Taseko River© This deposit is now bein§ explored by the Taylor Windfall Gold Mining Co. Ltd© which has installed a small m i l l . Gold i s found i n a very narrow vein and also in eluvium over quite a large area. The country rock is s i l i c i f e d tuff which has been bleached and pyritised. Quartz porphyry dykes about 12 feet wide cut the tuff. The vein is very irregular although i t s general trend i s parallel to the strike of the tuff. It probably averages about 3 inches in width though in places i t i s 7 inches* This auriferous vein consists of tourmaline, r u t i l e , quartz, sericite and talc© A great deal of the pyrite has been removed and often there is considerable quantities of limonite and coarse cellular gold i n the cavities formed by i t s removal© There are numerous l i t t l e pockets in the tuff consisting of tourmaline and tourmaline is impregnated through the country rock adjacent to the vein, but these other occurrences are not auriferous. -120-(g) .Taseko Motherlode Another high temperature gold deposit occurs on the other side of Taseko River about 1-g- miles southwest of the Taylor Windfall. This deposit, the Taseko Motherlode, consists of two wide fracture zones i n quartz d ior i t e . Of these, the westerly is the better defined and miner-alized, i t is 75 to 100 feet wide and the walls are nearly vertical, , Within this zone there is a close network of quartz veinlets averaging about |- inch width. Some of the fractures within the zone have not been f i l l e d and there are small cavities l ined with quartz crystals. Tourmal-ine and rutite are also present in the veinlets . Chalcopyrite i s the most abundant sulphide in the veinlets and is found to some extent i n the country rock, pyrite , sphalerite and galena also occur in the veins. Near the surface there has been considerable alteration and native gold has been set free. The gold values alone are too low to be commercial over mining width but the copper values are quite important and at the present time efforts are being made to develop large shoots of low grade gold-copper ore. fh) Sold Quartz Veins Aboxit 10 miles northwest of the northern end of Gun Lake are several veins i n the Eldorado sediments. These sediments at this point are now very much metamorphosed and their original character has been obliterated. The batholith, which i s exposed about a half a mile to the south, i s high in orthoclase and is nearly a granite. There is a sparsely mineralized zone 25 feet wide i n which occur lenses or veins of so l id arsenopyrite up to 5 feet in width. Although a l l of the arsenopyrite appears to be auriferous the highest gold values come from those parts of • -121-the zone i n which the arsenopyrite is disseminated, rather than from the solid lenses* fi) Popper Deposits Near the contact and in the section north of Gun Lake there are several copper prospects, which are not being explored now because of the low price of copper, but which might be of great importance i f there was advance in pr ice® Tritjaet* One of these, the T-i£yger Lake deposit, formerly called Copper 1 2 Mountain, has been described by Cams e l l and DoImage • i t occurs i n the granodiorite of the batholith near i t s contact with cretaceous volcanics about 15 miles northwest of Gun Lake. Intruded along the contact at this point is a mass of dior i te porphyrite 1200 feet wide. A section of the granodiorite 800 feet wide extends away from this porphyrite and although i t is quite fresh has been impregnated by chalcopyrite. Che mineralization is most intensive where the granodiorite occurs as nodules or pillows up to 18 inches i n diameter. These pillows have smooth surfaces hut no vis ible internal radical or concentric structure. The interior of these masses consists of normal massive granodiorite, while the internodular portions are ms.de up of miarol i t ic granodiorite, quartz and chalcopyrite. Calcite, pyrite and magnetite also occur in the fractured areas, and the sulphides carry gold and s i lver . The deposit is low in copper content, assays showing that across any considerable width there is less than lf0 copper. There are some richer zones, her.?ever, and i t is possible that the values would increase in depth because the samples so far assayed have come from the surface from which some of the copper may have been leached. 1. Camsell, C . SR 1918, Pt .B, pp. 25-28; 2. DoImago,V. SRl928,Ft.A,pp.86-9 -122-The mineralizing solutions probably came from the diorite porphyry and travelled along fractures in the granodiorite caused by the intrusion of the porphyry* There is another copper prospect with possibilities, in the quartz diorite near i t s contact, where the Taylor Windfall property i s * Here there is a mineralized zone in the altered rock though there i s no fracturing evident* The feldspars have been sericitized. the hornblende obliterated, and the rock i s now porous* The small cavities are lined with crystals of quartz and pyrite and pyrite^ chalcopyrite^ and molybdenite are disseminated throughout the rock. There are also gold and silver values but the average assays over large areas are low, though those made on fresh unleached samples are considerably higher* Another large deposit called the Spokane, is located in quartz diorite at the head of lieClure Creek, which flows into Taseko River from the south about 4 miles below the mouth of Battlement Creek* There i s a deposit, several hundred feet wide and of unknown width i n which the quartz diorite is cut by many veinlets of quartz, some of which contain cavities* There is some chalcopyrite i n these stringers but there i s a great deal more in the quartz diorite i t s e l f and i n several cases the values are quite high, higher than those from the other deposits* Bridge River Area / (See Fiflare 5) (a) General Considerations This area, i n which the largest gold producer in the province, the pioneer, i s located, is the second area, i n point of production, along the contact, being exceeded only by the Portland Canal area. A l l the mines are gold producers with minor values i n silver* -123-Most of the production has come from the properties located on Cadwallader Creek, a northwesterly flowing tributary of the south fork of Bridge River. At the present time attention i s being attracted to deposits on Bridge Hiver, near the mouth and for about 5 miles below the mouth of the south fork (Hurley Hiver) into which Cadwallader Creek drains« The Cadwallader Creek camp i s about 100 miles nor th of Vancouver and i s 55 miles by road from Shalath, a station on the Pacific Great Eastern Railway, 100 miles from the terminus at the head of Howe Sound* l McCann, V/. S. Mem. 130, pp* 45-99, 1922. Cockfield, W. E* S.R. 1931, Pt. A* pp. 49-57 Cockfield, W. E* & V/alker, J* ?* S. R* 1932, pt* A* pp* 64-71 Walker, J® E. S* R. 1933, Pt* A* pp.' 69-75 James, H. T* The Miner, Vol. 7 , Ho. 8* 1934* pp* 342-347 Dolmage, V* C. I* M. M. Bull. Ho* 268 1934, pp. 416-430 -124-( P) geology The general features of the areal geology have "been described above and w i l l not be repeated, but a brief description of the geology in the immediate xricinity of the important deposits is in order© In the Cadwallader Creek belt, that part of the Bridge.River area in which the most productive mines are located, McCann shows both the Bridge River Carboniferous series occurring and the Cadwallader Triassic series and just south of the producing mines a belt of greenstones, Sh^laps, between them. Underground and detailed work lave not confirmed this subdivision, which holds true i n other parts of the area. At any rate, the presence of members of the Cadwallader formation can not be recognized as such with any certainty. The group of pre-intrusive formations consists of sediments, chiefly a r g i l l i t e s and quartzites and interbeds of greenstone and a l i t t l e 1 serpentine. DoImage i s of the opinion that a l l these greenstones eere submarine lava flows, stating that they are interbedded and that the almost invariable presence of pil low structure j flow breccia^ and amygdules indicate their volcanic or ig in . There may be some intrusive phases present. These greenstones, which are of considerable importance local ly because they are host rocks for some of the veins, are now highly altered, but probably were of about the composition of andesite. They are now fine-grained green to dense grey green and are sometimes porphyrit ic . Intrusive into these rocks are irregular elongated masses of what has been called augite-diorite. Formerly i t was considered to be the only host rock of the veins but i t has been found that the veins do 1. Dolmage, V . op c i t p. 421 -125-extend from i t into the greenstones. The average rock should more properly he termed diorite with abundant hornblende. I t is a medium grained speckled grey and white rock in which hornblende, chlorite and feldspar can generally be seen with the naked eye. It grades into a finer darker rock which i s rea l ly an andesite and the equivalent of some of the greenstones. In places i t is impossible to t e l l whether the rock was a phase of the dior i te or one of the greenstones* A s tr iking feature of this diorite is the intricate system of veins present, They are narrow, seldom over a | of an inch,, mostly feldspar but some of quartz. The material in them may have come from the serpentinization of some of the greenstone and the fissures that they f i l l may have been caused by the expansion accompanying the formation of the serpentine. This d ior i te outcrops in a series of elongated bodies along a l ine para l le l to Cadwallader Creek and Hurley River. It i s post-Triassic but the upper l imit of i t s age i s uncertain. It is cut by later members of the Coast Range intrusives and presumably is late Jurassic in age and i s an early intrusion, intruded before the batholith had differentiated into the more acid types which came la ter . Closely associated with the augite diori te and often the host rock for gold quartz veins is a quartz d ior i te . It i s l ight colored, moderately coarse in grain, which i n most cases grades into the normal augite diorite as i f i t differentiated i n s i tu . In a few instances, the contact is sharp and the bodies assume the form of dykes. It appears to be very closely associated with the augite d ior i te . There are numerous fels i te dykes sometimes called a lbit i tes cutting these diorites'and older rocks, which often have quartz veins -125-assoelated with them, either along the walls or within them. Two or three miles northeast of the mines i s a large mass, helieved to he a satel l i te of the batholith, called the Bender quartz d ior i te . I t is a f a i r ly coarse-grained plutonic consisting of calcic feldspar, quartz,hornblende^and biotite and is believed to be younger than the other intrusives, principal ly because i t is fresher i n appearance than the other diorites and because i t is believed to be the same age as the rest of the Coast Range intrusives, which i n this area are post-lower Cretaceous© (Q\ Class i f icat ion In this area the gold quartz veins are of major importance. Antimony deposits are also present and i n some of them,which may be gradational between the gold quartz and the antimony, some high gold values have recently been discovered. There are occurrences of silver-copper and chromite, neither of which however are of economic importance. (d) Gold-Quartz Veins. Quartz veins containing gold values are abundant in this region but production has been confined to a small area in the v ic in i ty of stocks of augite diori te extending from the.Wayside Mine to the Pioneer. Bimerous other prospects have been explored northwest and southeast of this l ine but no other mines have been brought into production yet outside of three in this narrow s t r i p . Annual production from these mines is now i n the neighborhood of $5,000,000 i n gold and a small amount of s i lver . (e) Country Rock A l l the veins so far proved to be of economic importance have -127-Deen found i n bodies of augite diorite, though i n several instances they extend beyond the limits of these bodies. The other commons country rock f o r the veins i s the greenstone, although at the Pioneer the veins con-tinue with good widths and no decrease i n values when cutting quartz diorite and the so called a l b i t i t e , which i s really an apfcite or a soda granite of uncertain origin© Where the veins enter the serpentines or the arg i l l i t e s of the area, they become very narrow and pinch out. In regard 1 to the host rocks, Walker speaking of the whole area says, "The chief factor controlling mineralization appears to be the presence of a favorable rock formation competent -to maintain fissures and must f u l f i l l the requirements of being massive, hard and b r i t t l e . The serpentine rocks though massive and hard, do not fracture well and therefore have been looked upon with l i t t l e favor." |f) Wall Rock Alteration There has been intense alteration of the wall rock by the hydro thermal solutions. For a distance up to 8 feet from the vein walls this rock may appear as pale yellow greasy rock, and consists of quartz, sericite, mariposite, alunite, calcite, arsenopyrite and a few pyrite crystals. Sometimes there are some low gold values. Analyses show that there has been additions of carbon dioxide, potash and small amounts o f v/ater sulphur and arsenic, whereas some iron oxide has been subtracted from the wall rock and may have acted as a precipitant i n the vein. LIcCann says, "The mineralizing solutions must, therefore, have been warm alkaline waters containing much carbon dioxide, along with salts of sulphur and arsenic. I. Walker, J. F. S. R. 1933, Pt, A. p. 70. -128-(g) Mineralization The veins consist of quartz which in a great number has a ribboned structure, caused by the presence of thin films of sericite, mariposite, kaolin and much fine gold, lying an inch or two apart and running parallel to the vein walls. In some of the veins this ribbon structure is not present. The reins also contain calcite and in places some scheelite. Arsenopyrite and pyrite are the most common metallies; the others being pyrrhotite, native gold, galena, sphalerite, chalcopyrite, and stibnite. A telluride either calaverite or sylvanite lias been reported^, and marcasite occurs quite plentifully on the 14th level of the Pioneer. About 75%, of the gold occurs as the native metal, the other 25% being associated with the arsenopyrite and i n some cases with the telluride. Maraposite is often present i n the high grade ore shoots though not abundant in the rest of the vein. It is not, however, an indicator of high values always, because i t is found i n some veins wi th very low gold values© The gold content of the veins, particularly those of the Pioneer are in places very high, in some shoots running several ounces per ton over considerable distances. James says that the values i n the ribboned quartz are more uniform than i n the massive quartz with phenomenally rich pockets occurring i n the massive quartz erratically. Cockfield and Walker say i n regard to the temperature of deposition of the minerals that, "The mineral assemblage suggests that mineralization occurred under moderate, approaching high, temperature conditions. 1. McCami, W. S. Mem 130, p. 55. -129-fh) Vein Characteristics The veins are remarkably persistent, some of them being developed over 2000 feet. They have well defined walls, and the higher grade ones average about 3 feet in width although they are up to 12 feet in places. The veins on the Bralorne property are less regular and i n some cases are 65 feet wide, though the values over these widths are much lower. These great widths were probably caused by strike faults during the vein formation© Cross faults to date have not caused a great deal of d i f f i cu l ty , the s l ip i n most cases being small. One major fault on the King vein of the Bralorne property displaced the vein over 200 feet but this i s the largest displacement so far encountered. The ore occurs as definite shoots within the veins wi th low grade material between the shoots. The reason for these local primary richer parts of the veins are not known although some of them may have been caused by intersections with stringers or branch veins. It has generally been considered that the veins would probably extend to considerable depths and this prediction appears to have been confirmed by recent deep development. The mineralogy of the veins may be taken as good evidence that the temperature of deposition was f a i r l y high and the inference is that the minerals probably were deposited over a large vert ical distance. Also the fissures that permitted the circulation of the ore bearing solutions probably extend for considerable depths • below the surface for a l l the augite diorite bodies are small enough to be expected to fissure readily. If they had been larger or had expanded, -130-in cross-sectional area, rapidly from the surface, then the fissures i n them might have been restricted to a comparatively shallow surface zone® The main haulage shaft of the Pioneer now has been extended down to over 3200 feet below the surface and exploration from i t seems to show that there has been l i t t l e change in the vein or values. This is 1200 feet deeper than any deposits have been developed i n Br i t i sh Columbia as yet, previous to this the deepest being one of the Britannia mines, which is developed to about 2000 feet below the surface. (i) Origin The source of the vein forming solutions is unknown. Among the possible sources are the reservoirs from which, the augite diori te formed, 2,that from which the Bendor batholith formed and 3, the magma from which the main mass of the Coast Range intrusives formede The fact that a l l the veins occur in or near bodies of augite diorite indicates that there is probably some connection between them and that the veins were probably formed from a magmatic residue after the diorite magma had differentiated and the intruded bodies had consolidated and had been fractured. Another indication that the augite diorite magna may have been the source is that similar gold quartz veins have not been found i n or near the other intrusives' masses in the d i s t r i c t * In favor of one of the other magmas being the source is the fact that there are other deposits i n the d i s t r i c t which are not associated with the augite d ior i te . Part icularly the antimony deposits which occur i n a f a i r ly well defined zone north of the zone in which the gold quartz veins occur and para l le l to i t . This may indicate that the antimony deposits were formed at lower temperatures farther from the main batholith by solutions coining from the central magma© Regarding the localization of the deposits, Cockfield and 1 Walker say that there appear to he three principal, factors which had an influence on the mineralization. First, the manner in which the diorite intrusions are strung out suggests that they occur along a line of structural weakness, strengthened partly by the intrusions, but s t i l l weak at the time of fissuring, the fissures mostly being parallel to the length of the zone. Second, the augite diorite and the associated host rocks are physically more competent to maintain fissures than the sur-rounding rocks. Third, there is the possibility that the augite diorite and the surrounding rocks retained some of the heat from the intin sion until the period of mineralization and were more favorably situated, because wanner, than cooler rocks at greater distances from the augite diorite intrusives. Antimony Deposits A number of deposits i n which the dominant metal is antimony with minor amounts of gold and silver occur. They are restricted to a belt running northwest a few miles north and roughly parallel to the gold quartz zone. Hone of them have been developed yet for their antimony content. They a l l occur in some members of the Bridge River series near large quartz porphyry dykes. Generally there are shear zones bordering the dykes and i t is these which contain the veinlets. Quartz f i l l s and replaces these shear zones and i t contains lenses of ore. On most of the properties, stibnite is practically the only metallic mineral present. In a few, small amounts of galena and sphalerite 1. Cockfield, W. S. and Walker, J. F. S. R. 1932, Pt. A, p. 64 - 1 3 2 -have been found. Most of the lenses of sulphides are less than 4 feet in length and 1 foot i n -width* She close association of the deposits and the quartz-porphyry dykes is suggestive of some connection between them. Some of the dykes are rather similar to some which have been found cutting the Bendor quartz diorite and this may indicate that they are related to that body. The veins may not be genetically related to the dykes but only structurally because the intrusion of the dykes created easily replaced shear zones. The presence of stibnite as the predominant metallic mineral i s considered good evidence that they were formed at low temperatures not far from the surface* (kl Intermediate Type* Intermediate between these antimony deposits and the gold quartz deposits are a group of properties developing gold ores i n which arsenic and antimony are rather high* Included among these are the Minto, Congress, Olympic, Federal and a few others. At the present time Minto i s the only one producing although several of the others are said to have ore bodies developed* Recent development at Minto has indicated the presence of a rich shoot at greater depth that has hitherto been reached. There also seems to be a change in mineralogy in depth and the ore which has been considered d i f f i c u l t of treatment appears now to be more amenable to ordinary milling practice* These deposits occur as veins in shear zones i n massive green-stone. The veins which are up to 6 or 7 feet wide consist of quartz with pyrite, arsenopyrite, galena and stibnite* -133-Their location .and mineralogy seem to point to an or ig in related to that of the other deposits described above. One source probably to the south theoretically could have supplied the material for the vein forming solutions. Whether i t did or not has not been ascertained by recent work* Pemberton Area 1  (a) General Considerations This area is a short distance south of the Bridge Eiver and is adjacent to the station of pemberton on the Pacif ic Great Eastern Railway about 60 miles from the terminus at Squamish at the head of Howe Sound. There has been pract ical ly no production from this area although many of the properties are conveniently near the railway* Most of the properties were discovered about 20 years ago when the railway was constructed and many of them have been neglected since then. The most common type of mineralization i n the area is a high temperature replacement of limestone, in which the copper content is of greatest importance. Gold and si lver values are generally low. They a l l occur near what is considered to be the intrusive mass which caused the metamorphism of the limestone and the mineralization* There are other replacement deposits in the area, which occur along shear and fracture zones. These carry much the same type of mineralization as the limestone replacements. Vein deposits i n this area are of minor importance and contain minerals characteristic of deposition at f a i r ly low temperatures* and at some distance from the intrusive mass with which they are believed to be genetically related. 1. Cairnes, C. 3. S.R. 1929, Pt . A. pp. 8 4 - 9 9 . 1. Cams e l l , C. 3. R. 1917, Pt . B. pp. 19-20. (b) Description of Deposits About 7 miles northeast of P ember ton i s the Margery group, which is located on members of the Triass ic series of the area within a short distance of a large granitic intrasi on. The mineralization is greatest i n the limestone members of the series, the other members being but l i t t l e changed. Metasomatism of the limestone lias changed i t to a garnetite composed of garnet, epidote, calcite , and quartz and following this there has been the ore mineralizations The ore minerals are pyrite, magnetite, sphalerite, arsenopyrite and chalcopyrite. These are disseminated through the garnetite as well as concentrated in fractures within i t . A shear zone seems to have localized the deposits to those limestone members which i t intersects, probably because i t permitted the free circulation of the Mineralizing solutions. Some other calcareous members have been mineralized, but usually to a lesser extent than the limestones. In places, lenses of mineralization over 25 feet wide.have been exposed on the surface, but have not been explored at depth* Occurrences, more or less l i k e those on the Margery group, are found also on the Copper Queen claims on Owl River, about 5 miles north of Pemberton, and on numerous properties near the head of Tenquille Creek, 11 miles north of Pemberton. The Boulder creek properties, including the Copper King, Apex, Lake and Eagle groups are located along a zone of fracturing and shearing, 3|- miles long and up to 600 feet wide. This zone extends parallel to the western shore of Lillooet Lake, from i t s north end, for over three miles. Most of the rocks intersected by this zone are volcanics, with a few -135-sediments, mostly argillaceous, and some limestone, the zone of shearing striking parallel to that of the country rock. Hear and in the zone, the country rock has been very greatly altered, the limestone to garaetite and the other rocks so that they are unrecognizable, This alteration has been accompanied by replacement of the ore minerals magnetites, hematite, pyrrhotite, pyrite and to a lesser extent, chalcopyrite and sphalerite. numerous lenses or concentrations of these minerals occur in the zone, most of them being parallel to i t s length, although commonly they are faulted. On the Copper King group, where the zone is exposed by Boulder Creek, the zone of mineralization i s 300 feet wide. Along the other parts of the shear, the mineralization is confined to raich smaller widths. Most of the lenses so far prospected are too low to be of commercial value, but there has been only a small amount of surface exploration and very l i t t l e undergrouni work. So the south, the Apex group, and nearer the large granitic intrusive, the source of the deposits, there i s a greater proportion of pyrrhotite in the zone hut the values are about the same, 1 Cairnes states that , "The principal centers of mineralization seem to be related to a series of intersecting lines of movement which cross the main zone at different angles, but most commonly i n a direction of about north 65 degrees west." Other properties of a similar nature are the Pemberton within r r mile of Pemberton, and some of those at the head of Ten<juille Creek. The most Important vein deposits of the areajare found on the L i - l i ~ k e l group, south of Ten^uille Creek and about 11 miles north of Pemberton. Gutting a complex series of sediments, volcanics and greenstones 1. Cairnes, C. s. S. H. 1924, Pt. A. p. 89 are quartz veins containing pyrite, arsenopyrite, galena, sphalerite and chalcopyrite, lines of major shearing here strike northwest parallel to the general trend of the rocks while most of the veins strike northeast parallel to the direction of later and minor faulting.. In some of the veins the silver values are high, and polybasite i s not uncommon. In a few native silver lias also been found, of secondary origin, These minerals occur very irregularly and no ore bodies of any great size have yet been developed, 1 pemberton to Hope fa) General Considerations This long section of the eastern contact zone has not been extensively prospected and to date there has been no mineral production. Parts of i t are very inaccessible but other points particularly in the south are not far from the Fraser River and are f a i r l y easily reached. Prospecting i s d i f f i c u l t however because of the extremely rugged nature of the mountainss heavy ra i n f a l l and dense vegetation, A considerable sum of money has been expended i n the last few years in developing bodies of nickel-copper ore and i n a few other places quartz veins carrying values in gold and silver have been explored on the surface, (b) Quartz Veins o n In that section from Kanaka to China Bar the Fraser River, there are a few quartz veins. The Jubilee claims are about 6 miles from 1. Cockfield, W. 1* & Walker, J , P. S.R* 1933, Pt, A, pp 62-68 1, Cairnes, C, 3, S. R. 1929, Pt, A, pp 100-105 1, Horwood, H. C. Prelim, Repoit. Paper* 36-4, 1936 & 36-7, 1956* C.G,S, -137-the mouth of the Hahatlatch River and are located on quartz veins in a pyrit ized shear zone* Similar quartz veins u p to 7 feet wide occur i n the schists and serpentines. Pyrite and tetrahedrite a r e the chief metallic minerals® Similarly farther south, i n the section extending 15 miles north from Hope, quartz veins seem to he confined to schists and serpen-tine. As would he expected in rocks of this type, the veins pinch and swell wi thin.short distances. Pyrite, chalcopyrite^and sphalerite a r e the chief metallic minerals and some of them carry values in gold and s i lver . (e) Hick el Deposits At the property of 3. G. Hickel Mines Ltd. i s one of the most interesting deposits in the contact zone. It is 7 miles by road from Choate, a station on the G. P. R. about 110 miles from Vancouver© The annual report of the company issued recently states that there is over a mi l l ion tons averaging about 1.4 p e r cent nickel and car-rying some copper developed. Further development is planned before production w i l l be started. (di Geology The oldest rocks are small pendants of schist; they probably represent altered and replaced sediments. Younger than these is a pyrox-enitic hornblendite, generally coarsely crystal l ine and grey to greenish black. This rock occurs as a very irregular mass, about l | - square miles in area. The pyroxene which is mostly hypersthene is most abundant in the v i c in i ty of the concentrations of ore minerals. This mass of hornblendite -138-i s cut by dykes, and intruded by diorite, which is grey, medium-grained and consists of andesine and hornblende with small amounts of pyroxene, • biotite, apatite, epidote, magneti te and sulphides (pyrrhotite). The hornblende is probably an earlier differential*of the magma that later produced the diorite* There has been some displacement of the basic mass by tension faults, which cross i t in north-northwest and north-northeast directions. (e) Ore Bodies The developed ore bodies consist of disseminations of the ore minerals in the hornblendi te, i n which about half of the ore body consists of gangue. There are bodies i n which there is a greater proportion of gangue but these are too low i n nickel content to be commercial. There are also small veinlets which are not of economic importance. The ore bodies are believed to be mostly e l l i p t i c a l i n shape, and are scattered haphazardly through the mass. To date there have been 13 different bodies developed, many of which do not outcrop on the surface. Pyrrhotite is the most abundant sulphide and i s accompanied by penilandite and chalcopyrite, Others are pyrite, magnetite and chromite and small amounts of cobalt, gold, silver, platinum and palladium are presents (f) Origin Cairnes i s of the opinion that they are magmatic segregations and Horwood considers that they originated as segregations but have been enriched by later veinlets. Cockfield and Walker however are of the opinion that they have been formed by hydrothermal replacement, along lines of structural weakness, although there were some sulphides -139-original ly present. They consider that the occurrence of sulphides in the diorite and of sulphides and quartz i n the cracks of hypersthene of the honiblendite; the replacement of hornblende by sulphides; and the apparent orientation of the deposits in a definite direction are suggestive of replacement rather than original segregation. Replacements of hyper-sthene and hornblende crystals varying from thin films oecu ring along cracks to almost complete replacements may be seen, and as the fractures could not form until, the rock had consolidated, i t seems as i f there must have been some replacement. The ore bodies thus would appear to have been formed where original concentrations of sulphides in the rock coincide- with zones in which there has been considerable replacement. There are a few other deposits near 3. C. nickel which contain some nickel but they have not been developed to any great extent. /4& CHaPTSR V I 1 ; SUM&IA3Y AtTD OOITCLIJSI PITS Topography She Coast Range of British Columbia extends along? the coast from the valley of the Fraser River to the head of Lynn canal. To the north of Lynn canal i t continues in the same direction to merge with the Yukon plateau near Kluane Lake. East of this range i s the Interior Plateau into which the range merges; sometimes abruptly, sometimes gradually. The Coast Range is extremely ragged and irregular, the altitude of mountains in i t ranging from 6 0 0 0 to 13000 feet. It has been severely glaciated and abundant evidence of this glaciation i s . preserved in the rock forms. Deeply incised in the range are several transverse valleys which provide means of access to the interior,, Many of these deep valleys are now fiords over considerable parts of their length, caused by depression due to the great weight of ice which but recently covered the surface. The elevation of the Coast Range over the Interior plateau is probably due to greater elevation i n Tertiary times when the whole area was uplifted and also to the greater resistance to erosion which the rocks of the Coast Range have» In the north, the plateau lias almost assumed the aspect of a very mountainous region, due to rapid erosion and claciation, but the greater part of i t is f l a t with a few deep valleys. Over great parts of i t , the plateau effect has been enhanced by thick flows of nearly horizontal lava® -141-Geology predominant above a l l the other geological features i s the composite Coast Range batholith whose eastern contact over long distances coincides with the topographic contact between the Coast Range and the Interior Plateau, This batholith, phases of which range from pre-Cambrian to Tertiary in age, i s composed largely of granodiorite. Granite quartz diorite, diorite and more basic phases are also present,, there being a tendency for the periphery to be more basic than the interior. Also a tendence for the rocks of the eastern portion to be more acidic than those of the west. To the east of the batholith i s a great thickness of sediments and volcanics which have been intruded by the batholith. The older ones, including rocks of pre-Cambrian and early Palaeozoic age are found only in the northernmost section of the contact. At intervals along i t s length Carboniferous and Permian rocks are exposed, Mesozoic rocks are also abundantly represented intermittently along the contact. The feature of a l l these rocks is the immense amount of volcanic material which they contain. Most of the pre-batholithic rocks have been complexly folded and intensely altered near the contact, these effects decreasing as the distance from the contact i s increased. Overlying this group is the next younger, the post-batholithic group. Of these the oldest are Lower Cretaceous though i n several places, rocks of this age are pre-batholithic. These are less altered and are in general only gently folded. They are generally separated from the batholith by a band of the older ones, but in a few places, actually overlie the batholith. Most of these rocks are either of fresh water or volcanic origin. -142-There are considerable local thicknesses of unconsolidated rocks of glacial and recent origin. These form a mantle which covers the under-'lying rocks. They are very diversified but are not of much interest when the batholith i s being considered. Mineral Deposits  (a) general Discussion Before concluding the discussion on the mineral deposits associated with the eastern contact of the batholith some ideas of general interest in connection wi th such deposits w i l l be discussed* The evidence regarding the origin of deposits such as have been described undoubtedly favors a magmatic origin. This evidence i s considered thoroughly in most recent text books on economic geology® It is now considered that the majority of deposits of this type are formed from raagmatic residues which formed during the differentiation of a magma which ultimately forms a pl&tonic mass and associated hypabyssal and extrusive rocks. The occurrence of ore deposits i n and near such a mass i s not, however, universal and there are certain requirements particular to the formation of ore deposits* 1 Broadly, these requirements are : 1® Adequate supply of material 2. Appropriate physico-chemical conditions 3* Suitable l o c i of deposition Cb) Source of Minerals Upon the f i r s t of these, the source, depends the possibility of there being any mineralisation. The composition of the magma when i t was originally injected into the earth's crust determines the amount 1. Bruce, 3. I . Mineral Deposits of Canadian Shield 1933, p. 4 -143-aiid nature of the metallic minerals which may ultimately he deposited from some one of i t s differentiates. These magmas may differ considerably in the proportions of some particular element although the total com-position may he very similar. The magma from which the Sast Range batholithic rocks had their source seems to have been r i c h in most of the metallic minerals. An exception to this seems to have been i t s lack of t i n , no deposits of which have been described. Tin is an uncommon metal yet there are some batholiths with which i t is associated and the Coast Range batholith does not appear to be one of these. Among the •metals that have been deposited are gold, silver, lead, sine, copper, nickel, platinum, arsenic, antimony, iron, molybdenum, tungsten, tellurium and others less common© The extent to which differentiation has been completed is also of importance regarding the deposition of minerals. Field evidence has 1 shown that phosphdrus, sulphur, nickel, iron, chromium,.. titanium, platinum and copper are more commonly associated with basic phases of batholiths. On the other hand, fluriue, boron, lithium, zirconium, t i n , tungsten, tantalum, cerium metals, molybdenum, thorium and beryllium are more often associated v/ith the more acidic phases. Gold and silver have a tendency to occur more often with acidic rocks hut commonly are found associated with some basic types; That i s , these elements mentioned above tend to follow either the "basic or acidic phase when differentiation is taking place and when the mineral deposits are fin a l l y formed they are found associated with a rock, the equivalent of which they accompanied during the differentiation. In connection with this, Buddington is in-S f . Buddington, Ac F. ••Bull. 800 U . S. S. 1929, pp. 37 5-382 clined to believe that the change i n composition of the Coast Range batholith from basic to acidic from west to east may be one reason why 'copper occurs more commonly along the western contact, having been concentrated in the more basic differentiates, while lead, zinc, gold, and silver accompanied the more acidic phases and are now more abundant along the eastern contact» to] Suitable conditions for -precipitation Assuming the presence of some metals in a magmatic residue, their precipitation from the solution i s dependent on the physico-1 chemical conditions * These include temperature, pressure, solvent, concentration, relative abundance in solution, reaction i n the solution as precipitation progresses and the character of the country rock» ''/here the last 5 conditions remain, approximately constant over a period of time, then the only changes of importance are the progressive decreases in temperature and pressure outward from the intrusive mass* This permits of a zoning of metals outward from the parent mass, the order i n B r i t i s h Columbia along the eastern contact being, starting at the highest temperature close to the batholith, tungsten, molybdenum, gold, copper, zinc, lead, silver and antimony* i n several cases, particularly in the Zymoetz River area, (See Figure 4 ) , i s this zoning noticeable along the eastern contact. I f however, there are changes in the other con-ditions named above, and i t is not to be expected that they usually remain constant, then i t is to be expected that this simple zonal arrangement of metals w i l l be complicated by differences due to changes in conditions as the mineralization takes place. There are an abundance of instances where a l l the deposits in a region are presumably related - 1 4 5 -to the batholith, but which do not seem to be arranged in zones around the intrusive. A l l of the above mentioned conditions can vary within wide limits and the deposits may be classified chiefly on the basis of the temperature and pressure at which they were formed. The deposits now exposed near the surface however, are also dependent'on the amount of erosion that has taken place, and i n the case of most of the deposits now found along the eastern contact, the erosion has been such as to have exposed mostly deposits which were formed at intermediate temperatures and pressures. That i s , most of the deposits formed near the surface, at comparatively low temperature and pressure, have been removed by erosion, whereas those deposits formed at high temperatures 'and pressures have not yet been exposed by erosion. (di Suitable l o c i of deposition Coming to the third requirement, a suitable loci of deposition, i t is seen that this is also of the utmost importance in the formation of ore deposits. There may be an adequate supply, and conditions may be such as permit deposition readily from the solutions, but unless there i s some means whereby the deposition from those solutions is confined to a small area, the resultant mineralization is lik e l y to be of very l i t t l e economic importance. This localization of deposition is usually effected by the host rock in either of two ways. Chemically, i t may be better suited for replacement or i t may have a precipitating effect on the solutions which traverse i t and therefore confine their load within i t s boundaries. Physically, i t may be a strong homogeneous bri t t l e rock that has been fractured and brecciated and these fissures w i l l then provide a route along which the ore-bearing solutions may -146-circulate and which also w i l l provide open spaces i n which they can precipitate their load of metals. An easily replaced rock as a limestone or some volcanics is generally of more importance i n localising hot solutions and consequently rocks of this type are more commonly host rocks for the higher temperature deposits. On the other hand, cooler solutions have less ability to replace other minerals and fissures, fractures and zones of shearing in competent rocks are of more importance in localizing cooler solutions, The contact metamorphic deposits described above are good instances of easily replaced limestone acting as a good host for hot emanations. Likewise, the numerous veins and partially replaced shear zones are examples of deposition by somewhat cooler solutions. A wide variety of rocks are capable of maintaining fissures but generally a r g i l l i t e s , serpentines and rocks which flow readily under stress are not© (e) Conclusions It is d i f f i c u l t to draw general conclusions as regards the mineral deposits associated with this batholith because of i t s complexity and the variety of geological conditions that are to be found along i t s contact. Some conclusions are advanced which do appear rational and to be expected as f u l f i l l i n g the conditions required for ore deposition as described in the paragraphs above*, 1, The majority of the mineral deposits are associated with the batholith although they are not a l l genetically related to the same phase nor are they a l l of the same age. In a few instances, as in the Portland Canal area, some deposits appear to he associated with more basic phases which preceded the main intrusion© -147-2. In some cases these are deposits which are related to stocks or other sat e l l i t e s , These generally appear to he some distance from the main contact and may he regarded as contemporaneous separate intrusions. Examples of these are the Hoc he De Boule and Hudson Bay mountain stocks, Those stocks immediately adjacent to the main mass may not have he en the source of mineralizing solutions because they cooled too quickly to differentiate or else they may be really hybrid rocks composed of a large 1 amount of assimilated matter which Hanson considers may be the ease in the Zymoetz River area, 3 , Gold, silver, lead and zinc are more common in the deposits found along the eastern contact than i s copper, Schofield considers that the copper deposits of the eastern contact are limited to a very narrow zone immediately adjacent to the contact because those deposits now exposed were formed on the flank of the intrusive rather than near i t s roof. Another possibility mentioned by Buddington i s that there may have been an original concentration of copper along the western em contact because of greater differentiation in the east/fphases of the batholith, 4, Zoning of metals outward from their source is evident in many cases, rat in a great many cases the simple zoning has been masked by redeposition during changed conditions. This zoning is unlikely to prove of importance on most properties because the zone in which any one metal occurs, i n the case of mesothermal deposits, is quite large. In 1, Hanson, G. proceed, R, S, C, 1927, p, 121 2, Schofield, 5. J. Memoir 132, G. S* C. pp 54-56 3 , Buddington, A. F, Bull. 800 U. ti. G» S. 1929, pp. 375-382 -148-some, however, which are more nearly epithermal, the changes i n mineralization may occur within quite short distances and these changes are generally of great economic importance. The recent developments at Minto seem to indicate that in a short distance a very favorable change in mineralization occurred. 5© Practically a l l the deposits are localized by the presence of a shear zone or fracture. Only those deposits formed in limestone at the contact with an intrusive appear to have formed without there having been previous fracturing. The deposit may have formed by replacement by solutions circulating along a zone of fissuring, or the deposit may have formed simply by f i l l i n g of an open fissure. In some areas there are impregnations of considerable areas, with sulphides but these have l i t t l e likelihood of becoming of economic Importance because the minerals were not concentrated within a single zone, i n 1 connection with these fractures, Schofield lias shown that they may be roughly classified into those that strike northwest and those that strike northeast and that the former are more commonly characterized by copper and the latter by gold and silver© 6 . Secondary enrichment has been of economic importance i n a few deposits but these are unusual and i t i s not to be expected that many more deposits w i l l be discovered in which secondary surface enrighments w i l l be found because most of the area lying on the flanks of a high range of mountains lias been severely glaciated© 1. Schofield, S, J, 0, I. M. M. Bull© #159, 1925© pp. 759-764. -149-Annual Report of the Bancroft, J . A . Bowen, H. L. Brock, R. W. Bruce, E . L . Buddington, A . P . , Ohapin, T. Burton, W. D. Burwash, E . M. J . Cairnes, C. E® Cairnes, D. D. Minister of Mines of B r i t i s h Columbia 1910-1934 i n C s "geology of the Coast and Islands between the Strait of Georgia and Queen Charlotte Sound" Memoir 23 G. S. C. 19Xg WA Geological Reconnaissance of the Fraser River Valley pan lytton to Vancouver" G. S„ C. Sum, Rept. 1912 "Eutsuk Lake Dis t r ic t " G.S.C. Sum. Rept. ' p t * A • 1920 '•Mineral Deposits of the Canadian Shield" MacMillans, Toronto 1933 "Geology and Mineral Deposits of Southeastern Alaska" U . S. Geol. surv. B u l l . 800 "Ore Deposition at Premier Mine" Ec . Geol. V o l . 21 "The Geology of Vancouver and Vic in i ty" University off Chicago Press, Chicago, 111. "Coquihalla Area" Memoir 139, G. S. C . "Pemberton Area, L i l looet Di s t r i c t " G* S» C. Sum. Rept. P t . A» "ITickeliferous Mineral Deposit, Emory Creek, Yale Mining Division" G. S. C. Sum. Rept. P t . A . "Lewes and Nordenskiold Rivers" Memoir 5, G. S. C. "Wheaton Di s t r i c t " Memoir 31, G. S. 0. "Portions of the A t l i n Di s t r i c t " Memoir 37, G. S. C. "Yukon-Alaska International Boundary" Memoir 67, G. S. Ce "Wheaton Dis t r i c t , Southern Yukon" G. So C. Sum. Rept. 1929 1926 1918 1924 1924 1924 1910 1912 1913 1914 1915 -150-Cairnes, D. D. Gamsell, C. Cockfield, W. E . Cockfield, W. E . and B e l l , H. H . Cockfield, W. S. and Walker, J . p. Dawson, G. M. Do Image, V. "Windy Arm Portion of Conrad Mining Di s t r i c t " G. S. C. Sum. Rept. 1916 "Reconnaissance along the P . G. E , Railway between Squamish and L i l looet " G. S. C. Sum. Rept. P t . B 1917 "Copper Mountain, Gun Creek" G. S. C. Sum. Rept. P t . B 1918 "Exploration between A t l i n and Telegraph Creek" G. S. C. Sum. Rept. P t . A 1925 "S i lver Lead in A t l i n Di s t r i c t " G. S. C. Sum. Rept. P t . A 1925 "Aishikik Lake Di s t r i c t , Yukon" G. S. C. Sum. Rept. P t . A 1926 "Whitehorse Copper Belt , Yukon" G. S. C. Sum. Rept. P t . A 1927 "Mining in Nor them B. C . " G. S. C. Sum. Rept. P t . A 1930 "Part of Cadwallader Creek Gold Mining Area" G. S. C. Sum. Rept. P t . A 1931 "Whitehorse Di s t r i c t , Yukon" Mem. 150, GSC 1926 "Cadwallader Creek, Gold Mining Area" G. S. C. Sum. Rept. P t . A 1932 "Nickel Bearing Rocks near Choate, B .C. " G. S. C. Sum. Rept. P t . A 1933 "Explorations in B. C . " G. S. C. .Bepte of Progress 1876-77 "Exploration in the Yukon Dis t r ic t " G. S. C. An. Rept. New Series, V o l . 3, P t . B 1887-88 "High Grade Silver Ores of the Stewart Dis t r ic t " Can. Min. Jour. V o l . 41 1920 "Coast and Islands of B* C. between Douglas Channel and the Alaskan Boundary" G. S. C. Sum. Rept. Pt . A 1922 -151-Bo Image, T® Gwillim, J . C« Hanson. G. "Chilko Lake and V i c i n i t y " Q-. S. C. Sum,, Rept. P t . A "Tatla-Bella Coola Area" G. s. C. Sum. Rept® P t . A "Gun Creek Map-Area" G. S. C. Sum. Rept. Pt . A "Bridge River Gold F ie ld " C. I. M. M. B u l l . 268 " A t l i n Mining Di s t r i c t " G. S. C. An. Rept. New Series, V o l . 12, p t . B "Reconnaissance between Kitsault River and Skeena River" G. S. C. Sum. Rept. Pt * A "Dolly Varden Mine" C.I.M.M. Trans, vol.25 "Reconnaissance between Skeena River and Stewart" G. S. C. Sum. Rept* P t . A "Prince Rupert to Burns Lake" G. S* C. Sum. Hept® P t . A "Reconnaissance i n Zymoetz River Area" G» S. C. Sum* Rept. P t . A "Zoning of Mineral Deposits in B* C . " Proceed. R. S. C. V o l . 21, Sect. 4 "Mineral Deposits of Al ice Arm Dis t r ic t " G. S. C. Sum. Rept. #t. A "Bear River and Stewart Map Areas" Mem* 159, G. S. C. "Northern Part of Portland Canal Area" G. S. C* Sum. Rept. P t . A~ "Portland Canal Area" Mem. 175, G.S.C. 1924 1925 1928 1934 1899 1922 1922 1923 1929 1925 1927 1928 1929 1951 1935 Hanson, G. and Phemister, T . C. Norwood, H. C. "Topley Map Area" G.S.C. Sum.Rept* Pt*A 1928 "South Part Fraser River-Harrison Lake Region" G. S. C. Paper 36-9 1936 "Nahatlatch Region" G.S.C. Paper 36-7 1936 -152-Hurst, M. S. James„ H. T. Jones, R. H. B. Kerr, F . A* Lay, D. Leach, W. W. Lees, E . J . Leroy, 0. E . "Tungsten Deposits near Hazelton" G. S. G. Sum. Rept. P t . A 1924 "Britannia Beach Map Area" Mem. 158 G.S.C. 1929 "Features of Pioneer Geology" The Miner V o l . 7, #8 Vancouver, B. C. August 1934 "Geology and Ore Deposits of Hudson Bay Mountain" G. S. C. Sum. Rept. P t . A 1925 "Preliminary Report on Stikine River Area" G. S. C. Sum. Rept. P t . A 1926 "Second Preliminary Report on Stikine River Area" G. S. C. Sum. Rept. P t . A 1928 "Preliminary Report on Iskut River Area" G. S. C. Sum. Rept. P t . A " 1929 "Taku River D i s t r i c t " G. S. C. Sum. Rept. P t . A 1929 "Mineral Deposi ts of Taku Di s t r i c t " G. S. C. Sum. Rept. P t . A 1930 "Explorations between Stikine and Taku Rivers" G. S. 0. Sum. Rept. P t . A 1930 "Whitewater Gold Belt, Taku Di s t r i c t " G. S. C. Sum. Rept. P t . A 1952 "Coast Range Composite Batholith" Trans. R. S. C. V o l . 26, Sec* 4 1932 "Lode Gold Deposits of B. C . " B u l l . 1, B. C. Bureau of Mines . 1932 "Skeena River D i s t r i c t " G.S.C. Sum. Rept. 1909 "Geology of Lake Laberge Map-Area" Reprint Trans, of Reyal Canadian Institute V o l . 20, P t . 1 1934 "Main Coast of B. C. and Adjacent Islands, included in New Westminster' and Nanaimo Dis tr ic t s " G. S. C. Pub. 996 1908 Lindgren, W« •'Mineral Deposits" McGraw H i l l , New York 1933 Marshall, J . R. MoCann, W. S» MeConnell, R, G® Okulitch, V . J* O ' H e i l l , J . J . Schofield, S. J* and Hanson, G. Smitheringale. W. V . Spencer, A. C* Walker, J . F . Wright, F . E . Wright, F» E . and Wright, G. W. -153-"Whitesail-Tahtsa Lakes Area" G. S, C. Sum, Rept. P t . A 1924 "Eutsuk Lake Area" G. S, 0. Sum. Rept. P t . A 1925 "Lakelse Map Area" G. S, G. Sura. Rept. Pt .A 1926 "Geology and Mineral Deposits of the Bridge River Map-Area" Mem. 130, G. S. C. 1922 "WMtehorse Copper Deposits" G. S, C. 1909 "Mineral Deposits of the Eastern Contact of the Coast Range Batholith" Master's Thesis University of B. C. 1932 "Economic Geology of the Hazelton Di s t r i c t " Memoir 110„ G. S. C. 1919 "Cranbrook Map-Area" Mem. 76, G. S. Cc 1915 "Fissure Systems of B. C . " C« I. M. M. B u l l . 159 July 1925 "Geology and Ore Deposits of Salmon River Di s t r i c t " Memoir 132 1922 "George Gold-Copper Mine Stewart, B. C « " Bo. Geol. V o l . 23, #2 1928 "Pacif ic Mountain System in B. C. and Alaska" Geol. Soc. of America, Bulla V o l . 14 1903 "Li l looet Map-Area" G. S. C. Sum. Rept. P t . A 1933 "Unuk River Mining Region" G. S. C. Sum. Rept. 1905 "Ketchikan and Wrangell Mining Distr icts , Alaska" U. S. Geol. Surv. B u l l . 347 1908 Section <r/#tj AC f4eHft//y re/tf//j/T a/ mwa/ Partes /<? //ie tnfrvs/v^s wt/cA Mey arr fe*>e-//re//y mJ&ea&f&J. CEOLOG/CAL MAP SHOWING COAST RANGE BATHOLITH and ASSOCIATED ROCKS Sca/e 3/.S6m//ej /<? / *rcb A » it m /» * m / $ 5> 


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