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Geology of the Harper Creek copper deposit Belik, Gary David 1973

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GEOLOGY OF THE HARPER CREEK COPPER DEPOSIT by Gary David B e l i k B.Sc, (Honors), University of B r i t i s h Columbia, 1970 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of Geological Sciences We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA November, 1973 In p resent ing t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e fo r reference and study. I f u r t h e r agree tha t permiss ion fo r e x t e n s i v e copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . It i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l ga in s h a l l not be a l lowed without my w r i t t e n p e r m i s s i o n . Department of Geological Sciences The U n i v e r s i t y of B r i t i s h Columbia Vancouver 8, Canada Date 2 1 / 1 2 / 7 3 ABSTRACT This study investigates the geological setting of the Harper Creek copper deposit. The r e l a t i o n of the deposit to structure and stratigraphy as well as the age and nature of the mineralization are discussed. Copper mineralization i s confined to tabular-shaped zones within metasedimentary and metavolcanic rocks of the Eagle Bay Formation. A l -though mineralization does not appear to be s t r a t i g r a p h i c a l l y controlled, stratigraphy was important for the l o c a l l i z a t i o n of higher-grade material. Large-scale structures appear to have had an important role i n the channeling of 'ore-forming' f l u i d s . The deposit i s thought to be genetically related to the formation of a large east-west oriented antiform. Mineralizing f l u i d s of probable hydrothermal metamorphic o r i g i n migrated into t h i s structure and replaced favorable host rocks. Although tenuous, evidence presented suggests the age of mineralization i s between Upper T r i a s s i c (Karnian or Lower Norian) and Lower Jurassic-Upper T r i a s s i c . i i . CONTENTS Page Chapter I INTRODUCTION 1 Location and A c c e s s i b i l i t y 1 General Character of the Area 1 History of Development 3 Chapter I I REGIONAL GEOLOGY 4 Rocks of Uncertain Age 4 Monashee Group 4 Eagle Bay Formation i 4 Serpentinite 6 Proterozoic or Paleozoic 7 Kaza or Cariboo Group 7 Paleozoic 7 Fennel1 Formation 7 Cache Creek Group 7 Mesozoic. . . . . . . . . . . . 8 Cenozoic 8 Kamloops Group 8 Chu Chua Formation 8 Sk u l l H i l l Formation 9 Miocene to Pliocene Plateau Basalt 9 Tertiary? and Quaternary Volcanism 9 B a t h o l i t h i c and Related Rocks 9 Chapter I I I PETROLOGY 11 Eagle Bay Formation 11 Unit 1 13 i i i . Page Unit 2 14 Unit 3 16 Unit 4 16 Unit 5 17 Unit 6 17 Unit 6a 18 Unit 6b 18 Unit 7 18 Unit 8 19 Metaraorphism of Units 1 to 8 20 Titanium 20 Age and Dis t r i b u t i o n of the Eagle Bay Formation . . 22 Andesite Dykes (Unit 9) 22 Ch l o r i t e - B i o t i t e Gneiss (Unit 10) 23 Metamorphism of Unit 10 24 Chapter IV STRUCTURE ; 30 Eagle Bay Formation 30 Small-Scale Structures 30 Foliations 30 Linear Structures 33 Folds 35 Fractures 37 Large-Scale Structures 38 Andesite Dykes 38 C h l o r i t e - B i o t i t e Gneiss 40 Interpretation 40 Ages of Deformation 42 i v . Page Chapter V MINERAL DEPOSITS 48 Mineralization 49 Main Period 49 Sulphides 49 Stage 1 51 Stage I I 53 S i l i c a t e s , Oxides and Carbonates 54 Alt e r a t i o n 55 Paragenesis 56 Form of the Deposits 58 Structural Controls 58 Stratigraphic Controls 59 Second Period 62 Sulphur Isotopes 62 Genesis 63 Chapter VI POTASSIUM-ARGON AGE DETERMINATIONS 70 Chapter VII CONCLUSIONS 72 REFERENCES 74 APPENDIX A. Description of Mineral Deposits Within Part of the Adams Lake and Bonaparte Lake Map-Areas.77 APPENDIX B. Description of Samples used for Potassium-Argon Age Determinations 86 V LIST OF TABLES Page Table I Modal Range of Harper Creek Rocks 12 I I General Lithologies of the Eagle Bay Formation, Harper Creek 13 I I I Titanium Values of Some Eagle Bay Rocks, Harper Creek . . 21 IV Structural Features of the Eagle Bay Formation, Harper Creek . 41 V Primary and Secondary Minerals i n the Harper Creek Area . 48 VI Sulphides Deposited During the Main Period of Mineralization, Harper Creek 50 VII Potassium-Argon Age Determinations 70 v i . LIST OF FIGURES Page Figure 1 Location map • 2 2 Geology and mineral deposits of part of the Adams Lake and Bonaparte Lake map-areas 5 3 Plot of modal data for Thuya, Raft and Baldy batholiths . 10 4 Geology of the Harper Creek area i n pocket 5 Schematic diagram to i l l u s t r a t e structures i n rocks of the Eagle Bay Formation 31 6 Plot of poles to S 2 32 7 Plot of northwest-and northeast-plunging wrinkle lineations and average great c i r c l e for S 2 34 8 Plot of early and late (kink and open) f o l d axes and average great c i r c l e for 36 9 Plot of poles to fractures 38 10 S i m p l i f i e d sketch of the Raft, Thuya and Baldy batholiths 44 11 Sequence of deposition of primary minerals during the main period of mineralization 57 12 Structure Contour Map of the 'footwall' of the main copper-bearing horizon . . . . . . . . 60 13 Graphical plot of a diamond-drill hole log with corresponding titanium and copper values . . . . . . . . . 61 <v 34 14 s. S values for p y r i t e and chalcopyrite 64 15 Occurrences of Harper Creek-type deposits 66 LIST OF PLATES Plate 1 Photograph of fragmental greenstone from Unit 2 26 2 Photograph of fragmental greenstone from Unit 2 26 3 Photograph of a l b i t e - s e r i c i t e quartzite from Unit 6a. . . 27 4 Photomicrograph of fragmental p h y l l i t e from Unit 7 p l a i n polarized l i g h t 27 v i i . LIST OF PLATES (Cont.) Page Plate 5 Photograph of fragmental p h y l l i t e from Unit 7 27 6 Photomicrograph of c h l o r i t e p h y l l i t e , p l a i n polarized l i g h t 28 7 Photomicrograph of c h l o r i t e - r i c h p h y l l i t e , p l a i n polarized l i g h t 29 8 Photomicrograph i l l u s t r a t i n g carbonate prophyroblast pa r t l y replaced by sphene, p l a i n polarized l i g h t 29 9 Photograph of sandy graphitic p h y l l i t e from Unit 5 i l l u s t r a t i n g r e l a t i o n between bedding and 46 10 Photograph showing early f o l i a t i o n folded into upright subisoclinal f o l d .46 11 Photomicrograph of sandy graphitic p h y l l i t e from Unit 5, p l a i n polarized l i g h t . 47 12 Photomicrograph showing late s l i p folds 47 13 Photomicrograph showing sulphide occurring as replacements of carbonate porphyroblasts, p l a i n polarized l i g h t . . . . . 68 14 Photomicrograph showing part of a Stage I I vein, p l a i n polarized l i g h t 68 15 Photograph i l l u s t r a t i n g c h l o r i t e a l t e r a t i o n which imparts a speckeled appearance to some of the rocks . . . . 69 16 Photomicrograph showing c h l o r i t e a l t e r a t i o n associated'with a Stage I I vein, cross n i c o l s 69 LIST OF SECTIONS SECTION I 8,800E i n pocket I I 10,000E i n pocket I I I 10,800E i n pocket IV 12.060E i n pocket V 14,200E i n pocket VI 14.500E i n pocket v i i i . ACKNOWLEDGMENTS Financial support for t h i s study was provided by Noranda Exploration Co. Ltd. and by teaching assistantships at the University of B.C. The writer g r a t e f u l l y acknowledges the assistance given by Dr. A.E. Soregaroli i n the selection of the thesis and for his patience and constructive c r i t i c i s m s throughout the completion of the study. Drs. R.B, Campbell and D.J. Tempelman-Kluit from the Geological Survey of Canada and Dr. P.B. Read from the Department of Geology helped with useful d i s -cussions. Potassium-argon age determinations were furnished by J.E. Harakal from the Department of Geophysics. Special thanks go to Miss P. McFeely for her assistance i n drafting and to my wife Kathy for her patience and understanding. 1. Chapter I INTRODUCTION The purpose of t h i s study i s to investigate the geological setting of the Harper Creek copper deposit, and hopefully, to provide some understanding of the geological evolution of the area. The f i e l d work, on which t h i s study i s based, was carried out from 1970 to 1972. Surface mapping was done on a scale of 1 inch equals 400 feet using survey gr i d s , roads and topography for control. Mapping was hampered by both the scarcity and general poor quality of surface exposures. Location and A c c e s s i b i l i t y The Harper Creek copper deposit i s located within the Adams Lake Map-Area, B r i t i s h Columbia, at the headwaters of Harper Creek. The c i t y of Kamloops i s about 75 miles to the south and the v i l l a g e of Birch Island i s located some 7 miles to the northwest (Figure 1). Access to the region i s by the main l i n e of the Canadian National Railway or Highway 5. Both routes follow the North Thompson Valley and pass within 6 miles of the thesis area. The property can be reached by traveling east from Birch Island v i a a gravel road that follows the south bank of the North Thompson River. About 8 miles from Birch Island, the Jones Creek road i s then followed southward for 12 miles to a t r a i l e r camp situated at the property. General Character of the Area Topography i s moderate to steep with elevations ranging from less than 4500 feet to greater than 5700 feet. The area i n general i s under thick 3. forest cover with heavy underbrush. At higher elevations small marshy alpine meadows p r e v a i l . An old forest burn occupies the central and southwest parts of the map-area and to the east many areas have been, or are currently being logged. History of Development Part of the deposit was staked by Noranda Exploration Company, Limited i n A p r i l , 1966 as a result of reconnaissance geochemical work. The ground to the east and south of the Noranda claims was subsequently staked for Quebec Cartier Mining Company, a subsiduary of United States Steel Corporation, i n June, 1966. Exploration on the two properties was carried out independently u n t i l 1970, at which time a j o i n t venture was formed with Noranda supervising the continued exploration and development. Exploration techniques employed included s o i l geochemistry, geophysics, geology, diamond d r i l l i n g and trenching. To date, more than 9 miles of trenching has been done and some 130 diamond d r i l l holes have been completed. 4. Chapter I I REGIONAL GEOLOGY The geology of parts of the Adams Lake and Bonaparte Lake Map-Areas i s shown i n Figure 2. The most prominent geological feature of the area i s a northerly trending belt of highly deformed, metamorphosed Paleozoic and Mesozoic? eugeosynclinal rocks of the Eagle Bay Formation which, together with the rocks of the Shuswap Metamorphic Complex (Monashee Group), define the western l i m i t of the eastern f o l d b e l t . This belt i s flanked on the west by r e l a t i v e l y undeformed and unmetamorphosed Late Paleozoic and Mesozoic eugeosynclinal volcanic and sedimentary rocks. The d i v i s i o n between the two provinces i s obscure and appears to be gradational. Rocks of Uncertain Age Monashee Group The Monashee Group or Shuswap Metamorphic Complex are part of a series of highly metamorphosed rocks mapped by Dawson (1895) near Shuswap Lake and la t e r named 'Shuswap terrane'. Daly (1912) l a t e r examined t h i s same series of rocks along the shores of Shuswap Lakes and Adams Lake. Rocks of the Monashee Group are highly deformed and metamorphism i s generally of s i l l i m a n i t e grade. Gneisses are by far the most common rock types, but amphibolite, quartz-mica sc h i s t , quartzite, marble and skarn are l o c a l l y abundant. In the Adams Lake Map-Area Monashee Group rocks are intruded by a large number of g r a n i t i c s i l l s , dykes and small stocks. Eagle Bay Formation Rocks of the Eagle Bay Formation are equivalent to the Adams Lake and Fig 2. Geology and minera l deposits of part of the A d a m s Lake and Bonaparte Lake m a p - a r e a s ; modi f ied from G.S.C. maps 48 1963 and 1278A. Legend r QUATERNARY basalt flows, basaltic cinder cones, basaltic arenite. conglomerate breccia, rubble TERTIARY MIOCENE AND/OR PLIOCENE " plateau lava; olivene basalt, basalt andesite, ash, breccia, basaltic arenite EOCENE AND(?) OUGOCENE KAMLOOPS GROUP Skull Hill Formation: datite, trachyite. basalt, andesite, rhyolite Chll Chua Formation: conglomerate, sandy shale, orkose, coal I i quartz monionite, granodiorite, quartz diorite. diorite; 1 pegmatite, apilite JURASSIC porphyritic augite andesite breccia and conglomerate; minor andesite. arenite. tuff, argillite. {lows: siltslone. grit, breccic O N V O < 10 TRIASSIC OR JURASSIC •quartz diorite and granodiorite; minor diorite. monzonite, syenodtorite , gabbro , horn blend i te TRIASSIC NICOLA GROUP augite andesite and breccia, tuff, argillite, greywacke, grey limestone, shale, phyllite, siltstone U O 1 <; a a. PENNSYLVANIAN AND PERMIAN CACHE CREEK GROUP •^^B-an volcanic arenite. greenstone, argillite, phyllite; minor schist I limestone, basaltic andandesitic flows, amphiboiite. cong-lomerate and breccia MISSISSIPPIAN AND/OR LATER Fennel Format ion: pillow lava flows, greenstone, greenschist, argillite. chert, limestone, breccia r.. O 5 N o a. WINDERMERE OR CAMBRIAN AND LATER KAZA OR CARIBOO GROUP ^^HHHB feldspalhic quartz-mica schist, micaceous quartzite, black siliceous § phyllite, marble, chlorite schist, greenstone, amphiboiite S h u s w a p Terrane MOUNT IDA GROUP Eagle Bay formation; greenstone, greenschist. chlorite schist, phyllite, limestone, quartz-sericite schist, quartzite. volcanic agglomerate, quartz - feldspar -chlorite gneiss, trachytic tuff marble and limestone; minor greenstone and phyllite MONASHEE GROUP gneiss, quartz-mica schist amphiboiite, quartzite. marble, pegmatite mineral deposits f \ vein and/or fracture mineralization Q deposit conformoble or subparallel with bedding or schistosity Note: for a description of deposits refer to appendix A metals Q copper g molybdenum Q lead, zinc, silver H gold Q barite. silver • urananium. rare earths 6. Niskonlith Series of Dawson (1895) and include the Adams Lake greenstone, Tshinakin limestone and Bastion schist of Daly (1912) as well as the 'Barriere formation 1 described by Uglow (1922). In the Vernon Map-Area, Jones (1959) mapped the Eagle Bay Formation as part of the Mount Ida Group which he includes i n rocks of the '.Shuswap terrane'. In the Adams Lake Map-Area Campbell (1963) divided the Eagle Bay Formation into four unnamed uni t s . On his map they appear as follows: 5. Greenstone, greenschist, c h l o r i t e s c h i s t , p h y l l i t e , limestone, quartz-sericite s c h i s t , quartzite, volcanic agglomerate 4. 4a, dark grey and brown p h y l l i t e (commonly limy), limestone, s e r i c i t i c quartzite; minor greenstone, quartz-feldspar-chlorite gneiss, and meta-conglomerate; 4b, trachytic t u f f and breccia 3. Grey and buff weathering, white, grey, and buff marble and limestone; minor greenstone and p h y l l i t e 2. Undivided; includes rock types common to 4a and 5; minor quartz-mica schist and amphibolite Because of the close proximity and compositional s i m i l a r i t i e s , the Eagle Bay Formation may include parts of the Cariboo Group, Fennell Formation, Cache Creek Group and Nicola Group. Serpentinite Four small masses of serpentinite outcrop within the area of Figure 2 (not shown i n Figure 2). Two occur within rocks of the Eagle Bay Formation, one within the Nicola Group and one i n contact with rocks of the Thuya batholith. Their age and r e l a t i o n to the surrounding rocks i s uncertain. 7. Proterozoic or Paleozoic Kaza or Cariboo Group An area around the eastern end of Mahood Lake, i n the Bonaparte Lake Map-Area, i s dominantly underlain by quartz-mica schist and micaceous quartzite. Black p h y l l i t e , quartz-hornblende-mica s c h i s t , marble, c h l o r i t e schist and greenstone are also present but i n minor amounts. These rocks were mapped by Campbell and Tipper (1971) as part of the Kaza or Cariboo Group. Paleozoic Fennel1 Formation Dawson (1895) included rocks of the Fennell Formation i n the lower part of his Adams Lake Series. These rocks were la t e r described and named the Fennell Formation by Uglow (1922). Campbell and Tipper (1971) correlate the Fennell Formation with the Antler Formation of the Sl i d e Mountain Group. Aphanitic or very f i n e l y c r y s t a l l i n e greenstone forms the bulk of the Fennell Formation. P i l l o w structures are common and at some l o c a l i t i e s well exposed by railway and highway cuts. Dark grey to black a r g i l l i t e , p h y l l i t e and chert are generally r e s t r i c t e d to the eastern part of the formation where they occur as beds and lenses interlayered with and intruded by green-stone. At Mahood Lake fine-grained amphibolite and d i o r i t e are found with the greenstone. Cache Creek Group Dominantly c l a s t i c rocks with minor carbonate underlie an area on the west side of the North Thompson Valley i n the southwest corner of Figure 2. These rocks were mapped and l a t e r described by Campbell and Tipper (1971) as belonging to the eastern part of the Cache Creek Group. F o s s i l evidence 8. indicates the rocks range i n age from Early Pennsylvanian to Late Permian. An interesting aspect of t h i s part of the Cache Creek Group i s the preponderance of c l a s t i c rocks (mainly greywacke and volcanic arenite) and the general absence of chert and thick masses of limestone common to the group elsewhere. Hesozoic Two groups of dominantly Upper T r i a s s i c rocks have been mapped within the Bonaparte Lake Map-Area. One group, thought to be correlative with the Nicola Group, consists of augite andesite flows with breccia, t u f f , a r g i l l i t e , greywacke and grey limestone. Fine-grained c l a s t i c rocks, mainly a r g i l l i t e , s i l t s t o n e and black shale, characterize the second group, but p h y l l i t e and black limestone are also abundant. In the eastern part of the Bonaparte Lake Map-Area, contemporaneous Jurassic rocks have been divided into two units by Campbell and Tipper (1971). One consists of volcanic and c l a s t i c rocks with the l o c a l development of a basal conglomerate sequence. The other consists of coarse fragmental volcanic rocks i n which the fragments are porphyritic augite andesite. Cenozoic Kamloops Group The Kamloops Group includes two formations; l ) a lower sedimentary u n i t , the Chu Chua Formation and 2)an upper volcanic sequence, the S k u l l H i l l formation. Chu Chua Formation Five small areas around L i t t l e Fort, i n the North Thompson Valley, are underlain by a sequence of conglomerate, sandstone and sandy shale. These 9 . rocks are Eocene in age and unconforraably overlie the Fennell Formation. They are apparently conformably overlain by the Upper Eocene to Miocene Skull H i l l Formation. Skull H i l l Formation Acidic to basic volcanic flows, with related breccias, characterize the rocks of the Skull H i l l Formation. Individual members include dacite, trachyte, basalt, andesite and rhyolite. Miocene to Pliocene Plateau Basalt Many areas of B r i t i s h Columbia are underlain by plateau basalts of Miocene to Pliocene age. Within the Bonaparte Lake Map-Area these rocks are most commonly olivine basalt. Tertiary? and Quaternary Volcanism Three periods of Quaternary volcanism are represented in the Bonaparte Lake and Adams Lake Map-Areas. Exposures generally are confined to areas in and around the Wells Gray provincial park. Volcanism was of a basic nature and extended, intermittently, from Pliocene or Pleistocene through to Recent. Batholithic and Related Rocks Three large batholiths, the Thuya, Raft and Baldy, which occur within the area of Figure 2, have respective potasslum-argon ages of about 195 m.y., 105 m.y. to 140 m.y. and 80 m.y. to 100 m.y. As illustrated in Figure 3, there i s a corresponding compositional difference and degree of differentiation with age. Younger rocks trend towards an enrichment in potassium feldspar and quartz relative to plagioclase and tend to be of more variable composition. There i s also a decrease in modal percent mafics with decreasing age. QUARTZ Fig 3. Plot of modal data for Thuya,Raft and Baldy batholiths; modified from G.S.C. memoir 363 pp. 72 and 73. Chapter I I I PETROLOGY The Harper Creek copper deposit i s situated about 2% miles north of the Baldy batholith (Figure 2). Copper mineralization i s confined to tabular-shaped zones within metasedimentary and metavolcanic rocks of the Eagle Bay Formation. The polydeformed host rocks are c h a r a c t e r i s t i c a l l y well f o l i a t e d and are l o c a l l y cut by discontinuous, blocky, altered andesite dykes. Between the Baldy batholith and rocks of the Eagle Bay Formation i s a zone of c h l o r i t e - b i o t i t e gneiss ranging from % to more than a mile i n width. Modal di s t r i b u t i o n s for the various map units have been summarized i n Table I. The data are at best semiquantitative and i n some cases conclusions are drawn from a limited number of observations. Data were drawn from obser-vations made i n the f i e l d and through the examination of some 70 thin sections. The s o l i d lines represent estimates for probable ranges i n values and dotted extensions represent areas of uncertainty. Determinations of a l b i t e and potassium feldspar were aided i n many cases by etching specimens with cold hydrofluric acid and staining with cobalt n i t r a t e solution. The carbonate i s mostly dolomite but the presence of some c a l c i t e i s indicated from acid tests and X-ray determinations. Pyroph y l l i t e , c h l o r i t o i d , stilpnomelane and paragonite were not i d e n t i f i e d i n the rocks. Eagle Bay Formation Within the map-area, the writer has subdivided the Eagle Bay Formation into 8 petrological map units which are summarized i n Table I I . For the d i s t r i b u t i o n of these l i t h o i o g i e s as well as other map units refer to Figure 4 ( i n pocket). Cross-Sections I to VI ( i n pockets) add a t h i r d dimension to 12. u i i i i r"r " T i i T i — i — r T T "T T" 1 T T 1 "I - 1 T " T I 1 T 1 1 V ew V) H •m £• it M • — — _. •o Tr & u u * Vi — — "< • w o* • c * t i i i i i i ° S 3 2 S | 1 1 1 1 1 1 O O J © o g 1 1 1 1 1 i © O Q O O O W * « « O 1 1 1 1 1 1 O O Q O O O c « * -*» eo O 1 l 1 1 1 1 O . O Q O O O «>• * « ID © | Unit O •0 u V c 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 . c o. «t> h m b. m u n - — | — w •S — to r* c M O M « ca — - -• c i z 1 1 1 1 1 1 ° S 3 8 8 8 1 1 1 1 1 1 ° a 3 S 8 8 1 1 1 1 1 1 ° 8 3 S 8 8 1 1 1 1 1 1 ° 8 S S 8 8 1 1 1 1 1 1 ° g 3 S 8 8 « - * i 13. the perspective. Unit 3 4 General Lithology Quartzo-feldspathic p h y l l i t e ( l o c a l l y well laminated); minor l i g h t green, laminated green-stone Fo l i a t e d , fragmental greenstone; c h l o r i t e p h y l l i t e Chlorite p h y l l i t e White to l i g h t green, we l l -f o l i a t e d , lustrous p h y l l i t e Graphitic and carbonaceous p h y l l i t e ; minor dolomite Source Rock(s) Ac i d i c flows? and/or tuffs? Basic t u f f ; l o c a l l y with abund-ant hornblende and/or ac i d i c volcanic fragments Basic t u f f Marls, sandy shales, argillaceous arenites; l o c a l l y tuffaceous Carbonaceous arenites, carb-onaceous shales, carbonaceous carbonates and carbonaceous marls; l o c a l l y tuffaceous 6a Orthoquartzite, s e r i c i t e quartzite, a l b i t e - s e r i c i t e quartzite Quartz arenite, feldspathic arenites, argillaceous feld-spathic arenites; l o c a l l y tuffaceous 6b Carbonaceous quartzite Carbonaceous arenites; l o c a l l y tuffaceous 7 8 Dark green fragmental p h y l l i t e Pebbly tuffaceous greywacke Chlorite p h y l l i t e , quartz-c h l o r i t e - s e r i c i t e p h y l l i t e , c h l o r i t e - s e r i c i t e p h y l l i t e ; minor c h l o r i t e quartzite Basic t u f f and tuffaceous sediments Table I I General Lithologies of the Eagle Bay Formation, Harper Creek. Unit 1 Pale to l i g h t green quartzo-feldspathic p h y l l i t e forms the bulk of Unit 1. The p h y l l i t e averages about 75 percent quartz and feldspar, 10 percent c h l o r i t e , 8 percent c l i n o z o i s i t e , 4 percent sphene and contains minor amounts of carbonate and s e r i c i t e . The feldspar i s a l b i t e and generally occurs as 14. anhedral untwinned grains. Chlorite and c l i n o z o i s i t e occur f i n e l y disseminated throughout the rock. The p h y l l i t e i s homogeneous but l o c a l l y well laminated. Laminae consist of c h l o r i t e and c l i n o z o i s i t e - c h l o r i t e - r i c h layers within a dominantly quartzo-feldspathic rock. Laminae are discontinuous, contorted and generally less than one centimeter i n thickness. The c l i n o z o i s i t e - c h l o r i t e - r i c h laminations are fine grained and contain, i n addition to c l i n o z o i s i t e and c h l o r i t e , up to 20 percent s e r i c i t e , about 5 percent quartz and feldspar, 5 percent sphene and minor amounts of tremolite and carbonate. Some larger laminae contain very fine laminations of sphene and c l i n o z o i s i t e . L o c a l l y , Unit 1 consists of l i g h t green, laminated greenstone. The greenstone contains about 30 percent fine-grained c l i n o z o i s i t e , 35 percent a l b i t e , 10 percent tremolite, 10 percent c h l o r i t e , 5 percent carbonate, 5 percent quartz and 4 percent sphene. Tremolite occurs as fine slender acicular crystals within quartz and feldspar and as coarser prismatic laths i n lamina-tions with c l i n o z o i s i t e and c h l o r i t e . Most of the feldspar and quartz i s very f i n e l y c r y s t a l l i n e , equigranular and anhedral. Porphyroblasts of a l b i t i c plagioclase are r e s t r i c t e d to coarser grained pods and laminations. Unit 2 l o c a l l y contains greenstone fragments which resemble some of the rocks of Unit 1. These fragments have p a r t l y preserved phenocrysts of horn-blende and feldspar and appear to be of volcanic o r i g i n . Unit 2 Fol i a t e d , fragmental greenstone and c h l o r i t e p h y l l i t e , mapped as Unit 2, outcrop over a small area north of the Noranda camp. The greenstone i s medium to dark green and contains angular to subrounded hornblende and/or greenstone 15. fragments up to 1 Inch across (Plates 1 and 2). Hornblende fragments exhibit various degrees of al t e r a t i o n to c h l o r i t e with lesser and variable amounts of epidote, a c t i n o l i t e and carbonate. Most hornblende fragments are part of single hornblende crystals and have sheared c h l o r i t i z e d margins. Some hornblende has pa r t l y preserved c r y s t a l outlines and some contain euhedral a l b i t e grains up to 2 mm i n si z e . Greenstone fragments consist of 50 percent fine-grained c l i n o z o i s i t e evenly distributed within a very f i n e l y c r y s t a l l i n e quartz-feldspar groundmass. Small, subhedral to euhedral hornblende pheno-crysts, which are p a r t l y altered to c l i n o z o i s i t e and c h l o r i t e , and feldspar phenocrysts pseudomorphed by carbonate are also evident. Chlorite p h y l l i t e and the matrix of the fragmental greenstone are fine grained and well f o l i a t e d . Where hornblende fragments are present, the matrix consists of a c t i n o l i t e , c l i n o z o i s i t e , feldspar, c h l o r i t e , sphene, carbonate and quartz. Fine acicular to lath-shape a c t i n o l i t e occurs oriented i n the plane of the f o l i a t i o n but coarser a c t i n o l i t e occurs as laminations p a r a l l e l to and cross-cutting the f o l i a t i o n . C l i n o z o i s i t e i s c h a r a c t e r i s t i c a l l y fine grained and evenly dis t r i b u t e d . A l b i t i c plagioclase occurs as very f i n e , anhedral, untwinned grains i n t e r s t i t i a l to other minerals. Sphene i s abundant and occurs as fi n e disseminations i n amounts up to 20 percent. Chlorite p h y l l i t e and greenstone of Unit 2 without hornblende fragments contain about 70 percent c h l o r i t e and 20 percent sphene with less than 5 percent feldspar and less than 2 percent c l i n o z o i s i t e . The textures and composition of the c h l o r i t e p h y l l i t e and the matrix of the greenstone of Unit 2 suggest that these rocks may have o r i g i n a l l y been basic t u f f s . Hornblende and greenstone fragments possibly represent volcanic-a l l y ejected material which were incorporated into the t u f f . 16. Unit 3 Dark green c h l o r i t e p h y l l i t e , assigned to Unit 3, has a uniform appearance and weathers a d u l l , dark green color. This p h y l l i t e , which i s v i r t u a l l y the same as the c h l o r i t e p h y l l i t e of Unit 2, contains c h l o r i t e i n excess of 50 percent plus sphene, quartz, feldspar, carbonate and minor c l i n o z o i s i t e . S e r i c i t e i s present i n some of the rocks. Sphene, as i n the rocks of Unit 2, i s abundant and present i n amounts up to 20 percent. Unit 4 Unit 4 consists of white to l i g h t green, w e l l - f o l i a t e d , lustrous p h y l l i t e . Varieties of p h y l l i t e , based on the r e l a t i v e abundancies of quartz, a l b i t e , s e r i c i t e , c h l o r i t e and carbonate, include: sericite-carbonate, s e r i c i t e , q u a r t z - s e r i c i t e , q u a r t z - s e r i c i t e - c h l o r i t e and s e r i c i t e - c h l o r i t e p h y l l i t e . The stratigraphic r e l a t i o n of these p h y l l i t e s i s unknown but they commonly occur i n t e r s t r a t i f l e d as lenses and discontinuous layers with gradational contacts. Varieties of p h y l l i t e , which generally are less than 50 feet i n thickness, may be repeated several times i n a d r i l l hole and there i s no observed systematic v e r t i c a l or l a t e r a l v a r i a t i o n within the p h y l l i t e s . Correlation of v a r i e t i e s of p h y l l i t e of Unit 4 between diamond d r i l l holes or from one outcrop to the next often was not possible. The p h y l l i t e of Unit 4 i s t e x t u r a l l y diverse. A l l rocks are well f o l i a t e d with a well-developed cleavage. Most are f i n e grained but many contain small pods and laminations of coarser grained material. Many rocks are t h i n l y laminated and readily s p l i t into t h i n sheets. Laminations, which consist of quartz-and feldspar-rich segregations, separated by a thin layer of soft p h y l l i t e , p a r a l l e l the f o l i a t i o n . Some p h y l l i t e contains porphy-roblasts of quartz, carbonate and a l b i t e . Porphyroblasts of quartz are most common and occur as clear rhombohedral, spherical and eye-shaped grains up to \ inch across. 17. The phyllite of Unit 4 probably was derived from marls, sandy shales and argillaceous arenites. A corresponding increase in sphene with increasing chlorite content of some of the rocks of Unit 4 suggests the source of titanium may be the same as for the sphene-rich chlorite phyllites of Units 2 and 3 (i.e. basic t u f f ) . Unit 5 Dark grey to black, graphitic and carbonaceous phyll i t e , mapped as Unit 5, occurs as scattered lenses and discontinuous, irregular-shaped bodies. The phyllite contains more than 30 percent graphite and carbonaceous matter. Sericite i s usually less than 10 percent and carbonate varies from less than 2 percent to more than 20 percent. Quartz content varies from less than 5 percent to 70 percent. Chlorite, although generally absent, i s present i n some of the rocks. Fine-to medium-crystalline, grey dolomite occurs as discontinuous tabular bodies within graphitic and carbonaceous phyllite. Dolomite beds generally are less than 2 feet and no more than 50 feet in thickness. Unit 6 Small outcrops of quartzite (Unit 6) occur scattered throughout most of Units 4 and 5. Outcrops of quartzite, which are too small to record at the map scale, occur as isolated, resistant knobs within recessive-weathering phyllite. Quartzite forms bluffs along the north bank of Harper Creek near the centre of the map-area. In some areas, quartzite occurs as thin beds interstratified with phyllite. Exposures containing more than 50 percent quartzite were mapped as part of Unit 6. Unit 6 i s divided into 2 units based on the presence or absence of 18. v i s i b l e carbonaceous matter. Unit 6a Unit 6a consists of orthoquartzite, s e r i c i t e quartzite and a l b i t e -s e r i c i t e quartzite. The rocks are white to l i g h t green, hard and r e s i s t a n t . Orthoquartzite contains more than 95 percent quartz as anhedral, t i g h t l y interlocking grains. Within the a l b i t e - s e r i c i t e quartzite and to a lesser extent within the s e r i c i t e quartzite d e t r i t a l grains are p a r t l y preserved (Plate 3). These rocks contain sand-size, angular to well-rounded quartz and feldspar grains i n a fine-grained, quartzo-feldspathic groundmass. S e r i c i t e occurs between sand grains and along cleavage planes. Unit. 6b Unit 6b consists of carbonaceous quartzite. Most carbonaceous matter occurs between framework grains but l o c a l l y f i l l s fractures cutting framework grains. O r i g i n a l c l a s t i c textures, as i n the rocks of Unit 6a, often are preserved. Unit 7 Resistant, dark green, fragmental p h y l l i t e , mapped as Unit 7, forms a prominent east-west ridge some 2000 feet i n length extending into the western part of the map-area. Light-colored, well-rounded fragments, which comprise about 50 percent of the p h y l l i t e , occur evenly distributed within a dark green, fine-grained, w e l l - f o l i a t e d matrix (Plate 4). Most fragments are 1 mm to 2 mm across but range from less than 0.1 mm to greater than 5 mm. Stratigraphic variance i n fragment size has the appearance of graded bedding (Plate 5). Fragment shape varies from i r r e g u l a r spheres to l e n t i c u l a r . Lenticular grains define a good l i n e a t i o n by t h e i r preferred orientation i n the plane of the 19. f o l i a t i o n . Most fragments are polymineralic with variable amounts of epidote, carbonate, quartz, feldspar, c h l o r i t e and s e r i c i t e . An average fragment contains approximately 30 percent a l b i t e , 20 percent epidote, 15 percent carbonate, 15 percent quartz, 10 percent c h l o r i t e , 5 percent s e r i c i t e and minor sphene. The fine-grained, w e l l - f o l i a t e d matrix surrounding frag-ments consists of about 40 percent c h l o r i t e , 40 percent sphene, 10 percent s e r i c i t e , 5 percent quartz and feldspar and 5 percent epidote. Very fin e -grained sphene occurs as disseminations and i n clusters which l o c a l l y exceed 80 percent of the matrix. Unit 7 may represent the metamorphosed equivalent of a tuffaceous pebbly greywacke. Fragments appear to have been detritus from a volcanic source. The chlorite-sphene matrix possible was derived from basic tuffaceous material. Unit 8 Unit 8 consists of medium to dark green, c h l o r i t e p h y l l i t e , quartz-c h l o r i t e - s e r i c i t e p h y l l i t e and c h l o r i t e - s e r i c i t e p h y l l i t e with minor amounts of medium to dark green c h l o r i t e quartzite. The p h y l l i t e s generally occur i n t e r s t r a t i f i e d as lenses and discontinuous layers with gradational contacts. Chlorite p h y l l i t e of Unit 8 i s the same as the c h l o r i t e p h y l l i t e of Units 2 and 3. Textures of q u a r t z - c h l o r i t e - s e r i c i t e p h y l l i t e and c h l o r i t e - s e r i c i t e p h y l l i t e resemble those of the p h y l l i t e s of Unit 4. D i s t i n c t i o n between the units i s based on the greater amount of c h l o r i t e present within the p h y l l i t e s of Unit 8. As i n the p h y l l i t e s of Unit 4, there i s a corresponding increase i n sphene with increasing c h l o r i t e content. Textures and the general association between sphene and c h l o r i t e suggest the rocks of Unit 8 were o r i g i n a l l y basic t u f f s and tuffaceous sediments. 20. Unit 8 apparently forms a gradational s e r i e s between Units 3 and 4. Metamorphism of Units 1 to 8 Metamorphic minerals present within Units 1 to 8 include: quartz, a l b i t e , s e r i c i t e , c h l o r i t e , sphene, carbonate, epidote, tremolite and actino-l i t e ; an assemblage c h a r a c t e r i s t i c of the quartz-alblte-muscovite-chlorite subfacies of the greenschist f a c i e s of regional metamorphism. Deformation, which accompanied regional metamorphism, was characterized by the development of a strong crenulation f o l i a t i o n which transposed bedding and an e a r l i e r f o l i a t i o n . I t was not determined whether the e a r l i e r f o l i a t i o n i s part of the same metamorphic event or indicates an e a r l i e r metamorphic episode. Deformation appears to have outlasted metamorphism. Equi l i b r i u m was not always attained during regional metamorphism; t h i n sections of hornblende-bearing l i t h o l o g i e s from Unit 2 reveal the hornblende weakly to intensely a l t e r e d to c h l o r i t e , epidote, a c t i n o l i t e and carbonate. Titanium Sphene, as previously noted, i s a major constituent of parts of Units 2, 3, 7 and 8. Within these u n i t s , c h l o r i t e - r i c h p h y l l i t e i s the p r i n c i p l e host f o r sphene. The f i n e grain s i z e , basic composition, abundance of sphene and the lack of volcanic textures suggest t h i s p h y l l i t e was o r i g i n a l l y a tita n i u m - r i c h basic t u f f . Most sphene occurs evenly disseminated or i n c l u s t e r s which appear opaque i n t h i n section ( p l a i n p o l a r i z e d l i g h t ) (Plate 6). By i n s e r t i o n of the condens-ing lens, opaque grains of sphene can be resolved as c l u s t e r s of minute, highly b i r e f r i n g e n t , anhedral to euhedral sphene c r y s t a l s , many of which have d u l l brown leucoxene? halos. This sphene appears to have formed during regional metamorphism and at least some occurs as p a r t i a l replacements of c l i n o z o i s i t e (Plate 7). Some sphene occurs as replacements of carbonate i n the matrix of p h y l l i t e and as p a r t i a l to complete replacements of carbonate porphyroblasts (Plate 8). Sphene of th i s character appears to post-date regional metamorphism and generally i s within and adjacent to areas of suphide mineralization, which suggests a hydrothermal o r i g i n for the sphene. 'Hydrothermal sphene' i s coarser grained than sphene formed during regional metamorphism and i s not opaque i n thin section (plain polarized l i g h t ) . In hand specimen, 'hydrothermal sphene' i s buff to orange colored. Unit Description a.Titanium b.Estimated Sphene Ratio a:b (weight percent) (volume percent) (approximate) 2 Fragmental green- 1.92 20 1:10 stone (hornblende fragments) 3 c h l o r i t e p h y l l i t e 1.20 15 1:12 7 fragmental p h y l l i t e 2.77 +20 1:7 8 c h l o r i t e p h y l l i t e 1.92 20 1:10 8 c h l o r i t e p h y l l i t e 2.29 +20 1:9 Table I I I Titanium Values of Some Eagle Bay Rocks, Harper Creek Titanium values obtained for Units 2, 3, 7 and 8 as well as the estimated volume of sphene for the rocks assayed are shown i n Table I I I . Rocks assayed for titanium contained l i t t l e or no 'hydrothermal sphene*. Table I I I also shows the estimated titanium: sphene ratios.: Although there i s no pretense that these estimates are accurate, they probably i l l u s t r a t e s i g n i f i c a n t l y higher r a t i o s than for pure sphene which would indicate a large substitution for titanium within the l a t t i c e structure of sphene formed during regional metamorphism (titanium: sphene r a t i o for pure sphene i s about 1:4). This assumption i s supported by petrographic, X-ray and polished section studies. In polished sections, under reflected l i g h t , sphene formed during regional metamorphism varies from yellow to dark red to steel m e t a l l i c . Yellow and red v a r i e t i e s display respective bright yellow and bright red in t e r n a l r e f l e c t i o n s . X-ray traces of t h i s sphene show a difference, by as much as 1 degree, i n the 26 position of the 002 peak. Age and D i s t r i b u t i o n of the Eagle Bay Formation The Eagle Bay Formation underlies a large part of the western half of the Adams Lake Map-Area and extends south into the adjoining Vernon Map-Area where i t was mapped as part of the Mount Ida Group by Jones (1959). The only f o s s i l l o c a l i t y discovered within t h i s formation has yielded conodonts of Middle Mississippian age (Campbell, personal communication). While much of the formation may be of t h i s age, i t possibly includes younger and/or older s t r a t a . Andesite Dykes (Unit 9) Dykes of altered andesite, mapped as Unit 9, were intersected i n some diamond-drill holes. The dykes have c h i l l e d margins and l o c a l l y incorporate fragments of p h y l l i t e . Although the cores of the dykes are r e l a t i v e l y un-deformed the margins are sometimes sheared and l o c a l l y well brecciated. Most of the dykes are porphyritic (plagioclase phenocrysts) and have a dark grey to green, fine-grained, pandiomorphic granular matrix. The dykes contain approximately 40 percent a l b i t e , 20 percent carbonate, 30 percent c h l o r i t e and b i o t i t e , 5 to 10 percent quartz, 3 percent sphene and minor 23. amounts of potassium feldspar and s e r i c i t e . Thin sections of andesite dyke reveal b i o t i t e weakly to intensely altered to c h l o r i t e . Some of the c h l o r i t e contains f i n e l y disseminated sphene. Carbonate occurs as patches and clusters of grains within and around polysynthetically twinned, t i g h t l y interlocked a l b i t e . The orientation of the dykes i n the map-area i s not precisely known because they have generally been observed only i n d r i l l core. One andesite dyke, south of the map-area, was observed to have a v e r t i c a l dip and a northerly s t r i k e . C h l o r i t e - B i o t i t e Gneiss (Unit 10) C h l o r i t e - b i o t i t e gneiss, designated as Unit 10, underlies a small area i n the southwest corner of the map-area. This fine-to medium-grained, moderately w e l l - f o l i a t e d gneiss contains approximately 35 percent a l b i t e , 20 percent quartz, 20 percent c h l o r i t e and b i o t i t e , 10 percent epidote and c l i n o z o i s i t e , 5 percent carbonate and 5 percent sphene. A l b i t e normally i s anhedral and untwinned. Chlorite occurs as an a l t e r a t i o n of brown, pleochroic b i o t i t e . C h l o r i t e - b i o t i t e gneiss, the same as Unit 10, outcrops south of the map-area. Here, the f o l i a t i o n i n the gneiss appears to define a large east-west oriented antiform, the core of which i s occupied by the Baldy batholith. F o l i a t i o n i n the gneiss south of the batholith dips 20 to 60 degrees south whereas f o l i a t i o n i n the gneiss north of the batholith dips 20 to 60 degrees north. The contact between gneiss and rocks of the Eagle Bay Formation i s 24. marked by an increase i n the degree of f o l i a t i o n i n the gneiss and l o c a l l y by the appearance of b i o t i t e and/or a c t i n o l i t e as fracture coatings and disseminations i n rocks of the Eagle Bay Formation. With increasing distance from the contact, the gneiss i s less f o l i a t e d and l o c a l l y displays a hypidio-morphic-granular texture. A l b i t e often i s euhedral, well twinned and t i g h t l y interlocked with quartz. At the headwaters of Foghorn Creek, about 5 miles west of Harper Creek, the gneiss contains pods, up to 10 feet across, of unfoliated quartz d i o r i t e . Within the quartz d i o r i t e , mafic minerals are partly to completely c h l o r i t i z e d . Metamorphism of Unit 10 Prograde metamorphic minerals within Unit 10 include: quartz, a l b i t e , b i o t i t e , muscovite, microcline, epidote, carbonate and sphene. The co-existence of a l b i t e and epidote and the presence of b i o t i t e l i m i t meta-morphism to either the quartz-albite-epidote-biotite or the quartz-albite-epidote-almandine subfacies of the greenschist facies of regional metamorphism. The lower-grade quartz-albite-epidote-biotite subfacies i s favored because of the absence of almandine garnet and because twinning i n plagioclase, which tends to be destroyed during metamorphism, i s s t i l l prevalent i n some of the rocks. Retrograde metamorphism of the gneiss has resulted i n p a r t i a l to complete c h l o r i t i z a t i o n of b i o t i t e . B i o t i t e and a c t i n o l i t e i n rocks adjacent to the gneiss i s seemingly anomolous because these minerals are younger than the regional metamorphism which affected these rocks. The following model i s suggested to explain t h i s anomaly: Both the gneiss and rocks of the Eagle Bay Formation were affected 25. by the same period of metamorphism. Near the end of metamorphism isotherms were lowered and metamorphism ceased in the upper, lower-grade metamorphic zones. At this time the gneiss, which was s t i l l hot, was folded and squeezed into the cooler overlying strata. This movement of hot gneissic rocks into rocks of lower metamorphic grade resulted in the raising of isotherms and the partial readjustment of the contact rocks to the new temperature conditions. Therefore, using this interpretation, the contact between the gneiss and rocks of the Eagle Bay Formation may, in part, represent a faulted biotite isograd. Plate 1 Photograph of fragmental greenstone from Unit 2. Dark frag-ments are partly altered hornblende and the matrix surround-ing fragments consists largely of actinolite, clinozoisite, chlorite, sphene and carbonate. The scale i s in inches. Plate 2 Photograph of fragmental greenstone from Unit 2. Fragments are light green greenstone and appear to be of volcanic origin. The phyllite surrounding greenstone fragments is largely composed of chlorite and sphene. The scale i s in inches. 28. Photograph of fragmental phyllite from Unit 7. Note the smaller fragment size toward the top of the specimen. The scale i s in inches. 1 mm 0 mm scale Photomicrograph of chlorite phyllite, plain polarized light. Sphene appears as opaque patches. 29. 0.5 mm 0 mm J L scale Plate 7 Photomicrograph of chlorite-rich phyllite, plain polarized light. Sphene appears opaque on the photo and apparently replaces clinozoisite (light grey, high r e l i e f grains). 1 mm 0 mm j i I ' l l ' scale Plate 8 Photomicrograph showing carbonate porphyroblast (right-center of photo) partly replaced by sphene (dark rim around porphyroblast), plain polarized light. Dark vein-like areas on photo consist of chlorite and sphene. 30. Chapter IV STRUCTURE Interpretation of the structural history of the Harper Creek area i s d i f f i c u l t because of complex structure, scarcity and general poor quality of surface exposures and l o c a l l y , by the superimposition of l a t e r hydrothermal events. Eagle Bay Formation Small-scale structures, which include f o l i a t i o n s , lineations, folds and fractures, are w e l l developed within the Eagle Bay Formation. Large-scale structures, notably folds, exist but are not readily apparent because of complex structure and s i m i l a r i t y of many l i t h o l o g i e s . Some of the data pertaining to the orientation of various structures are plotted on schmidt equal-area nets (lower hemisphere projections) and appear as Figures 6 to 9. Fold axis and fracture data were supplemented by data collected by others (Kirkland, 1971; Westerman, 1968). Small-Scale Structures F o l i a t i o n s The e a r l i e s t recognizable f o l i a t i o n , Sj., i s p a r a l l e l to subparallel to bedding. Where evident, t h i s f o l i a t i o n commonly occurs as microscopic quartz-r i c h and/or mica-rich laminations. Bedding and S i .have been transposed by a well developed crenulation f o l i a t i o n , S2. The l a t t e r , which dips uniformly to the north-northwest at about 30 degrees (Figure 6), was formed by slippage along irregular-spaced, 31. Fig 5. Schematic diagram to illustrate structures in rocks of the Eagle Bay Formation. Fig 6. Plot of poles to S2,(l44 plotted). 33. parallel zones up to 2 mm in thickness. Formation of S2 was accompanied by incipient crystallization of micas parallel to S2 and was followed by total recrystallization where transposition was complete. Deformation appears to have outlasted crystallization. Slickensided surfaces, designated as S3, were developed subparallel to S2 (Figure 5d). These surfaces (S3), which post-date S2, are only locally evident. Linear Structures The intersection of S\ or bedding with S2 defines a linear structure, L]_. This lineation appears on S2 surfaces as faint lines or bands (Figure 5a), which plunge northerly. The fold crests of minute gleitbret folds developed between S2 planes (Figure 5b) occasionally define another lineation which parallels Lj_, and also w i l l be refered to as L\. Wrinkle lineations are well-developed on S2. These lineations, which are designated L2, have the form of very small folds which typically are asymmetric and discontinuous. Wrinkle lineations, which plunge to the north-east and northwest parallel to S2 (Figure 7 ) , have apparently formed as a conjugate set (Figures 5a and 7 ) . Northwest-plunging wrinkle lineations are ubiquitous and often the only lineation present. Northeast-plunging wrinkle lineations are only locally evident. A third lineation, L3, occurs as striations on S3 surfaces (Figure 5d). This lineation is subparallel to northwest-plunging wrinkle lineations and indicates a northwest direction of movement. Other linear structures include mullions, quartz rods, boudin and + PLOT O F N O R T H W E S T - P L U N G I N G W R I N K L E L I N E A T I O N S . C O N T O U R E D . 66 P L O T T E D PER ONE PERCENT AREA 5 - 2 5 % A P L O T O F N O R T H E A S T - P L U N G I N G W R I N K L E L I N E A T I O N S . 6 P L O T T E D Plot of northwest-and northeast-plunging wrinkle lineations and average great circle for S2. 35. stretched pebbles, a l l of which p a r a l l e l L^. Folds Small-scale folds are not abundant within the Eagle Bay Formation and many are not v i s i b l e to the unaided eye. Folds e a r l i e r than those which deform S^ are not evident. Asymmetric, S-shaped, g l e i t b r e t f o l d s , designated as F^, deform bedding and S^ and have developed by transposition between S^ planes (Figures 5b and 5d). These fo l d s , which have fo l d axes defined by and a x i a l planes p a r a l l e l to S^, generally have amplitudes less than 1 cm and show a r e l a t i v e sense of movement of east to west. Gleitbret folds l o c a l l y were preceded by the development of small-scale, subisoclinal f o l d s , F^. Subisoclinal folds display transposition along S^ (Plates 9, 10 and 11) and appear to have developed as an early structure during the same deformation which produced S^ and F^. F^ folds have attenuated limbs, interlimb angles between 10 and 30 degrees and plunge northerly ap-proximately p a r a l l e l to F^. Most are reclined with a x i a l planes p a r a l l e l to S^, but some were observed i n an upright p o s i t i o n . Locally, p h y l l i t e s display kink f o l d s , F^, which deform S2 (Figure 5c). These folds developed as a conjugate set with amplitudes less than 10 cm and the same a x i a l orientations as the conjugate L^ wrinkle lineations (compare Figures 7 and 8). Geometry of kink folds suggests an o v e r a l l sense of move-ment from south to north with one limb p a r a l l e l to S^ and the other limb dipping steeply to the northeast or northwest. Northwest-plunging kink folds are better developed and on occasion both sets are exposed within the same outcrop. Development of kink folds was accompanied by renewed slippage 36. Fig 8 . Plot of early and late (kink and open) fold axes and average great circle for S2 . 37. along Conjugate open fo l d s , which are co-axial with kink folds, are l o c a l l y evident. These folds, which w i l l also be refered to as F3, generally have larger amplitudes than kink folds. The uniform orientation of the crenula-t i o n f o l i a t i o n S2 (Figure 6) indicates that F3, which deformed t h i s structure, does not form large folds within the area mapped. Small folds, designated as F4, developed by slippage on S3 (Plate 12). These fo l d s , which have a x i a l planes p a r a l l e l to S3 and f o l d axes normal to L3, are rarely evident. Fractures Fractures are ubiquitous within the area mapped. One set i s v e r t i c a l and s t r i k e s northwest. A second set dips steeply to the southwest. Both sets are weakly developed. A t h i r d well-developed set i s characterized by tension fractures. V e r t i c a l tension fractures s t r i k e from northwest to northeast but as synoptically shown i n Figure 9, they have two prefered orientations and form a conjugate set. Conjugate tension fractures are present within some outcrops although most contain only one set. Tension fractures t y p i c a l l y are d i s -continuous and occur en echelon. Their width i s 0.1 mm to greater than 3 mm with lengths of 1 mm to more than 5 meters. Tension fractures commonly are f i l l e d with c h l o r i t e and/or suphides. Tension fractures appear to have developed as late structures during the same deformation which produced the conjugate wrinkle li n e a t i o n s , l>2 and conjugate kink and open fo l d s , F3. The following observations support these 38. 1 Fig 9- Plot of poles to fractures,(l22 plotted); 39. conclusions: 1. A line drawn on Figure 9 which would bisect the angle between the conjugate set of tension fracture (approximately north 10 degrees west) would also bisect (Figure 7) and F3 (Figure 8). 2. Some tension fractures show displacements along planes parallel to the crenulation foliation, S2. 3. Most tension fractures transect and F3 without deflection. The f i r s t observation suggests that the tension fractures, and F3 developed during the same deformation. The second observation suggests that the de-velopment of tension fractures was in part synchronous with the formation of L2 and F3 (renewed slippage along S2 accompanied the formation of L2 and F3). That most tension fractures developed after and F3 is implicit in the third observation. Large-Scale Structures Large-scale structures, notable folds, are not apparent in the f i e l d but probably do occur. One such structure, near the center of the map-area, i s indicated by the sudden flexure of copper-bearing horizons. However, the geometry of this flexure, i s best displayed by the faulted lens of quartzite just below the Noranda camp (Figure 4). When reconstructed, this quartzite lens i s S-shaped and has the same geometry and orientation as the small-scale gleitbret folds developed between S2 planes. A similar large structure can be infered from the distribution of Unit 5 lithologies in the southern part of the map-area. These lithologies may outline the northern half of a subisoclinal fold which has been transposed into irregular-shaped lenses. Small-scale subisoclinal folds have the same orientation as this structure and display a similar style of transposition. Andesite Dykes The margins of altered andesite dykes locally are sheared and brecciated. 40. Int e r n a l l y , the dykes are r e l a t i v e l y undeformed. Slickensided surfaces, of the same appearance as S3, l o c a l l y are developed. C h l o r i t e - B i o t i t e Gneiss Alignment of b i o t i t e and/or c h l o r i t e imparts a good f o l i a t i o n to the rocks of Unit 11. This f o l i a t i o n p a r a l l e l s i n the overlying p h y l l i t e s and i s the only important structure developed. The f o l i a t i o n S3 and l i n e a t i o n L3 are weakly developed but folds and tension fractures are notably absent. Interpretation The keys to the structural history of the map-area are small-scale structures within the Eagle Bay Formation. These rocks exhibit the effects of four periods of deformation which are i n general agreement with the defor-mational history described by Campbell and Okulitch (1973) for the Mount Ida Group and Fyson's (1970) model of deformation for rocks i n the Shuswap Lake Area, B r i t i s h Columbia. E a r l i e s t recognizable deformation produced a f o l i a t i o n p a r a l l e l to subparallel to bedding. This structure does not appear to be related to macro- or mesoscopic folds but seems "to have been produced by some mechanism akin to i n t r a f o l i a l flow" (Campbell and Okulitch, 1973). The second period of deformation i s characterized by intense shearing with the development of a penetrative crenulation f o l i a t i o n , g l e i t b r e t t f o l d s and subisoclinal folds. Conjugate sets of f o l d s , wrinkle lineations and tension fractures were formed during the t h i r d period of deformation. The fourth, and youngest period of deformation, i s characterized by weak, nonpenetrative shearing with the development of slickensided surfaces and small s l i p - f o l d s . Structural features of the Eagle Bay Formation within the area mapped are summarized i n Table IV. Deformation Period Structure Description Relative Direction of Movement I I I I I IV u l S 2 F 3 E a r l i e s t recognizable f o l i a t i o n : p a r a l l e l to subparallel to bedding. Crenulation f o l i a t i o n ; transposes bedding and e a r l i e r f o l i a t i o n S]_. Intersection of S 2 with bedding or S^; crests of minute g l e i t b r e t folds. Subisoclinal folds with f o l d axes = I4; most commonly reclined with a x i a l planes = S 2; display transposition along S2« Gleitbret folds; S-shaped with a x i a l planes = S 2 and fo l d axes — Northwest- and northeast-plunging wrinkle lin e a t i o n s . Conjugate sets of kink and open folds; co-axial with L3. Tension Fractures Average north-south orientation; v e r t i c a l and form a conjugate set. S3 Slickensided surfaces. L3 Sliekensides on S3. S l i p folds with f o l d axes normal to L3 and a x i a l planes p a r a l l e l to S3. East to west Northerly Northerly Northwest Table IV Structural Features of the Eagle Bay Formation, Harper Creek 42. Emplacement of andesite dykes (Unit 9) post-dates the second period of deformation but appears to pre-date the fourth period of deformation. The dykes probably were intruded into tensional structures during or following the third period of deformation. As previously noted, an andesite dyke south of the map-area has a vertical orientation with a northerly strike. This attitude closely approximates the average attitude of tension fractures developed during the third period of deformation. The foliation in the chlorite-biotite gneiss probably was developed by weak, but penetrative, plastic shear during the f i r s t and/or second period of deformation. Notably absent from the gneiss are the subisoclinal and gleitbret folds which developed within rocks of the Eagle Bay Formation during the second period of deformation. Their absence may be explained by a difference in rock competency. Unit 10, an homogeneous lithology, possibly acted as a competent mass which did not yield to deformation as readily as the overlying incompetent, heterogenous mixture of metavolcanic and meta-sedimentary rocks representative of the Eagle Bay Formation. Within the map-area, the third period of deformation is not recorded in the rocks of Unit 10. However, Unit 10 does appear to form the core of a major antiform south of the map-area which may have formed during this deformation. The axial orientation of this fold i s east-west, normal to the maximum compression direction for the third period of deformation. The map-area i s situated on the north limb of this fold. Ages of Deformation Descriptions given by Campbell and Okulitch (1973) indicate that the Mount Ida Group (includes the Eagle Bay Formation) displays structures which characterize the f i r s t three periods of deformation within the area mapped by the writer. Campbell and Okulitch suggest a lower age limit of Upper Triassic 43. for the deformation(s) which produced these structures. This conclusion appears to be based, for the most part, on the correlation of an Upper Karnian or Lower Norian conodont-bearing limestone unit with the Sicamous Formation of the Mount Ida Group. A s i m p l i f i e d sketch of the Thuya, Raft and Baldy batholiths as shown i n Figure 10 i l l u s t r a t e s a close correlation between the orientation of these batholiths and large east-west trending folds which are thought to have formed during the t h i r d period of deformation. The Baldy batholith occupies the a x i a l region of one of these folds but i t s emplacement appears to post-date the formation of the f o l d . The implication i s that the emplacement of the Baldy batholith was strongly controlled by t h i s pre-existing structure. A sim i l a r s t r u c t ural control i s suggested for the emplacement of the Raft and Thuya batholiths. I f correct, t h i s implies that the upper age l i m i t for the t h i r d period of deformation i s Lower Jurassic-Upper T r i a s s i c (the oldest potassium-argon age for the Thuya batholith i s 198 ro.y.). The plot of modal data for the Thuya, Raft and Baldy batholiths i s shown i n Figure 3 and i l l u s t r a t e s a corresponding compositional difference and degree of d i f f e r e n t i a t i o n with age. Younger rocks trend towards an enrichment i n quartz and potassium feldspar r e l a t i v e to plagioclase and are more variable i n composition. The data appear to define a s t r a i g h t - l i n e d i f f e r e n t i a t i o n series which originates from the quartz d i o r i t e end of the f i e l d . The writer believes that the dykes of Unit 9 occupy tensional features developed during the t h i r d period of deformation and that the composition of the dykes would plot close to the bottom of t h i s trend. Becauserof t h i s apparent compositional s i m i l a r i t y and because of the apparent r e l a t i o n of intrusive rocks i n the area to structures developed during the t h i r d period . . > / u . ' ^ i . ^ - . v ! ; : j ' " ' — . .-.-;->:-"-!-.-.-.-.-.-.-.-.---.;.>;.x->I-I-»I-".*I-> <^  ::::v:::v:-Xv'.v'.vv "^"Vx-x-y; • • • • Xv.v.V.V sssr h A r IlK ^  > - J m v v ^ v, w^ ; u ,^ v . f ^ 7 B A L D Y . V A ^*m//m/^A A ^  7 v. BATHOLITH /.• * 1 1 7^ < A is. V A i "7 V v J . A THUYA BATHOLITH A 7 m - A < > 11M A ^  < V r -7 u v r 1 v ^ > A A^W > < > V v M A J1I ' 4 ~ H M \ BATHOLITH / < ^XXXXXv ^ • - ^ ^ V / " " W N - - : \ v / \ K - -V / /\ > Fig.10 Simplified sketch of the Raft, Thuya and Baldy batholiths. M E T A M O R P H O S E D STRATA W E A K L Y OR U N M E T A -M O R P H O S E D STRATA x A N T I C L I N E S Y N C L I N E H A R P E R CREEK scale: 1 in. equals 8 mi. 45. of deformation the writer believes the dykes are part of a d i f f e r e n t i a t i o n a l series and are as old or older than the rocks of the Thuya bat h o l i t h . I f correct, t h i s supports an upper age l i m i t for the t h i r d period of deformation of Lower Jurrassic-Upper T r i a s s i c . Although tenuous, evidence presented above indicate that the f i r s t three periods of deformation occurred between Upper T r i a s s i c (Upper Karnian or Lower Norian) and Lower Jurassic-Upper T r i a s s i c . The age of the fourth period of deformation i s unknown but possibly i s related to the intrusion of the Early Upper Cretaceous Baldy batholith. Plate 9 Photograph of sandy graphitic p h y l l i t e from Unit 5 i l l u s t r a t -ing r e l a t i o n between bedding (alternating dark and l i g h t laminations) and Note that bedding has been folded into F^ p r i o r to being transposed along S . Also note g l e i t b r e t folds (F 2) developed between S planes. Scale i s i n inches. Plate 10 Photograph showing early f o l i a t i o n (S^) folded into upright subisoclinal f o l d (F . ) . Note p a r t i a l transposition of F^ along S . Scale i s In inches. 4 7 . 1 mm 0 mm I i_i i i I. i i i i I scale Plate 11 Photomicrograph of sandy graphitic phyllite from Unit 5, plain polarized light. Photograph shows bedding (alternating dark and light lamination) folded into a subisoclinal struc-ture (F.). An early foliation (S ) i s developed parallel to bedding. Also evident are small, S-shaped, gleitbret folds (F 0) developed between S 0 planes. 1 mm 0 mm ' • i i ' I i i i i I scale Plate 12 Photomicrograph showing late s l i p folds (F^). Folds developed by drag along slickensided surfaces (S.). 48. Chapter V MINERAL DEPOSITS Within the map-area, mineralization i s widespread and characterized by a wide variety of sulphides, s i l i c a t e s , oxides and carbonates ( l i s t e d i n approximate order of decreasing abundance i n Table V). P y r i t e , the most abundant sulphide, i s found i n a l l rock types. Copper sulphides, notably chalcopyrite, are the only minerals of economic importance and occur almost exclusively within rocks of the Eagle Bay Formation (Units 1 to 9). PRIMARY SECONDARY Me t a l l i c limonite p y r i t e hematite manganese oxides pyrrhotite j a r o s i t e chalcopyrite malachite sphalerite c o v e l l i t e arsenopyrite azurite molybdenite hydrozincite galena melanterite tetrahedrite-tennantite native copper bornite cuprite cubanite chalcocite Non-metallic or Submetallic chrysocolla tenorite ? c h l o r i t e anglesite dolomite sphene magnetite quartz a l b i t e s e r i c i t e tourmaline magnesite r u t i l e b i o t i t e Table V Primary and Secondary Minerals i n the Harper Creek Area. 49. Iron oxides, the most abundant secondary minerals, have formed to depths i n excess of 200 feet. Secondary copper minerals generally are re-s t r i c t e d to near-surface exposures. Mineralization The main period of mineralization within the Eagle Bay Formation appears to have been, i n part, synchronous with the t h i r d deformational period. Sparsely mineralized quartz, carbonate and quartz-carbonate veins were developed during a second period of mineralization. Main Period The main period of mineralization developed i n two stages. The f i r s t and economically most important stage (Stage I) was largely synchronous with, but also preceded, folding of the t h i r d period of deformation. During deformation earlier-formed sulphides were being deformed and r e c r y s t a l -l i z e d as new sulphides precipitated. The development of tension fractures, a late phase of the t h i r d period of deformation, marked the beginning of the second stage of mineralization (Stage I I ) . Sulphides Sulphides deposited during Stage I mineralization are, i n order of decreasing abundance: p y r i t e , pyrrhotite, chlacopyrite, sphalerite, arsenopyrite, molybdenite and cubanite. P y r i t e , pyrrhotite and chalcopyrite together comprise more than 99 percent of the t o t a l sulphide. The p y r i t e : pyrrhotite r a t i o i s estimated at 5:1 and the pyrrhotite:chalcopyrite r a t i o i s about 3:1. Sphalerite, although widespread, rarely exceeds 1 percent. Arsenopyrite, molybdenite and cubanite are only l o c a l l y evident. 50. Chalcopyrite and minor py r i t e were the only sulphides deposited during Stage I I mineralization. The r a t i o of Stage I chalcopyrite:Stage I I chalco-py r i t e i s approximately 10:1. Stage I I I Occurrence 1) evenly disseminated 2) bands of disseminated sulphide 3) thin sulphide bands 4) smears along f o l i a t i o n planes 5) ir r e g u l a r veins and patches 6) i n thin conformable quartz and quartz-carbonate veins 7) massive sulphide lenses 8) replacements of p y r i t e 9) coating sphene grains 10) p a r t i a l to complete replacement of carbonate porphyroblasts 11) inclusions within other sulphides 12) coating tension fractures 13) vein f i l l i n g s 14) disseminations away from mineral-ized veins or fractures Sulphide(s) py, cpy, po, sph, arsenopyrite PY, cpy py, cpy cpy, po, mo, py py, cpy py, cpy py, po, cpy po, cpy PY, cpy py, cpy sph, cub cpy, minor py cpy, minor py cpy, minor py Table VI Sulphide Deposition During the Main Period of Mineralization, Harper Creek. Modes of occurrence for sulphides deposited during the main period of mineralization are summarized i n Table VI. Replacement textures characterize sulphides deposited during Stage I mineralization and planar structures defined by sulphide concentrations generally p a r a l l e l the crenulation 51. f o l i a t i o n , S^. Stage I I sulphides occur as vein and fracture f i l l i n g s and as disseminations adjacent to mineralized veins and fractures. Stage I Most p y r i t e and chalcopyrite deposited during Stage I mineraliza-tion occur evenly disseminated over large areas. Although chalcopyrite gener-a l l y i s associated with p y r i t e , p y r i t e without chalcopyrite i s commonly observed. Pyrite content does not exceed 10 percent. Chalcopyrite content rarel y exceeds 2 percent. Most p y r i t e i s fine to medium grained and euhedral. Fine-grained, anhedral chalcopyrite occurs i n t e r s t i t i a l l y . Other sulphides which occur evenly disseminated are sphalerite, pyrrhotite and arsenopyrite. Sphalerite, which does not exceed 1 percent, i s fine-grained, brown and resinous. Fine-grained pyrrhotite generally i s associated with chalcopyrite. Arsenopyrite, which i s only l o c a l l y evident, i s fine to medium grained and euhedral. Bands of disseminated sulphides, i n which the py r i t e content exceeds 10 percent and chalcopyrite may exceed 4 percent, occur sporadically within the disseminated sulphide zones. P y r i t e - r i c h bands are less than 5 mm to more than 30 feet i n thickness. Chalcopyrite-rich bands seldom exceed a thickness of more than 10 feet. Although somewhat coarser grained, sulphide textures are the same as i n the evenly disseminated zones. Laminations of pyr i t e and/or chalcopyrite occur within disseminated sulphide zones but are more common within bands of concentrated sulphide. Sulphide laminations are 1 cm or less i n thickness and p a r a l l e l the crenula-f o l i a t i o n , S ?. Some have been traced along s t r i k e for more than 20 feet. 52. Some sulphides are smeared on S^. These smears cover areas up to several square cm and are a few microns to 1 mm thick. Pyrrhotite, chalco-p y r i t e and molybdenite smears occassionally a t t a i n a m i r r o r - l i k e p o l i s h . P y r i t e smears are far less lustrous and often are d i f f i c u l t to see. Shear between planes, which accompanied folding as flexture s l i p during the t h i r d period of deformation appear to have caused development of smeared sulphides. The presence of undeformed sulphides on smear surfaces indicates sulphide deposition continued after folding. Within the quartzites of Unit 6, chalcopyrite and py r i t e commonly f i l l i r r e g u l a r veins and patches. Drusy c a v i t i e s , c h a r a c t e r i s t i c of open space f i l l i n g s l o c a l l y are evident. Within the p h y l l i t e s of Unit 4, py r i t e and chalcopyrite occur i n t h i n quartz and quartz-carbonate laminations. Laminations are but a few mm thick and p a r a l l e l S^. Laminations pre-date mineralization and are common i n nonmineralized rock. Lenses of massive sulphide were noted at a few locations. These lenses range from less than 5 feet to greater than 30 feet i n thickness and have sharp or gradational contacts with the enclosing host rocks. The p r i n -c i p a l sulphides are fi n e - to coarse-grained pyrrhotite and p y r i t e , with l o c a l concentrations of chalcopyrite. Most pyrrhotite occurs as p a r t i a l to complete replacements of p y r i t e i n rocks above the main copper-bearing horizon. Cubic pseudomorphs are common and many pyrrhotite pseudomorphs have py r i t e cores. Polished smears of pyrrhotite, which appear to be deformed pyrrhotite pseudomorphs of p y r i t e , 53. indicate alteration of pyrite to pyrrhotite occurred early in the f i r s t stage of mineralization. At a few l o c a l i t i e s , pyrite and/or cubic pseudo-morphs of pyrrhotite have been partly replaced by chalcopyrite. Sulphides developed during the f i r s t stage of mineralization also include: 1) pyrite and chalcopyrite coating fine-grained sphene, 2) pyrite and/or chalcopyrite partly to completely replacing carbonate porphyroblasts (Plate 13) and 3) minor sphalerite and cubanite as small inclusions in chalcopyrite. Stage II Most chalcopyrite deposited during Stage II mineralization occurs in tension fractures. Tension fracture density varies from less than 1 to more than 10 per square foot but generally less than 10 percent contain chalcopyrite. Generally, the number of tension fractures mineralized with chalcopyrite increases towards copper-bearing horizons. Tension fractures which display offsets along planes parallel to S^  are thought to have develop-ed during folding as offsets appear to be the result of flexure s l i p . Chalcopyrite also occurs within veins which generally consist of three or more of the following: dolomite, chlorite, tourmaline, albite, quartz and minor r u t i l e . Gangue minerals locally are zonally arranged parallel to vein walls (Plate 14). Disseminations of chalcopyrite and minor pyrite adjacent to mineralized veins and fractures are common. Narrow sulphide halos around tension fractures are confined to the immediate vi c i n i t y of the fracture. Sulphide halos around veins are more extensive and occur as irregular disseminations 54. and as laminations of disseminated sulphide which parallel S^ . Silicates, Oxides and Carbonates Silicates, oxides and carbonates deposited during the main period of mineralization include: carbonate, albite, quartz, sphene, chlorite, magnetite, tourmaline and r u t i l e . Carbonate, albite and quartz are vein constituents but also occur as porphyroblasts disseminated within sulphide zones and as disseminations adjacent to mineralized veins and fractures. Poryphyroblasts, which are subhedral to euhedral, are 0.5 mm to 4 mm across. Carbonate porphyroblasts are most abundant and often display twinning indicative of dolomite. Albite porphyroblasts were observed only adjacent to mineralized veins. Some sphene, probably of hydrothermal origin, was observed as replace-ments of phyllite adjacent to mineralized veins (Plate 14). Sphene, pre-viously noted as occurring as partial to complete replacements of carbonate porphyroblasts and carbonate within the matrix of some phyllites, i s also thought to be of hydrothermal origin. Chlorite occurs within veins and coating tension fractures. In thin section, between cross nicols, this chlorite displays an anomalous berlin blue interference color suggestive of penninite. Although tension fractures mineralized with chalcopyrite almost always contain chlorite the converse i s not true. Massive magnetite occurs within sulphide lenses and as separate lenses and layers. Magnetite i s coarse grained and contains variable amounts of chlorite and chalcopyrite. 55. Dark green to brown tourmaline occurs as vein f i l l i n g s and as replace-ments around tourmaline-bearing veins. Rutile, which locally displays elbow twinning, occurs as an accessory mineral in veins. Alteration Alteration of host rocks during the main period of mineralization involved an early recrystallization of sericite and chlorite formed by re-gional metamorphism and a later chloritization. Recrystallized micas are petrographically distinguished from the crenulation foliation by the synchronous extinction of micas and by a difference in optical properties of chlorite. Chlorite formed by regional metamorphism i s light to medium green and displays a light to dark grey birefringence (possibly prochlorite) whereas recrystallized chlorite i s generally a darker green and displays an anomalous blue birefringence (possibly penninite). The distribution of zones of recrystallized mica i s not precisely known but there appears to be a close spatial relation to areas of sulphide mineralization. The age of recrystallization appears to largely predate the third period of deformation. Formation of secondary chlorite as an alteration of sericite was close-ly related to sulphide deposition. This chlorite, which optically also has the appearance of penninite, occurs as zones of complete replacement, irregular patches, fine disseminations and as envelopes adjacent to mineralized veins and fractures. Completely chloritized phyllite of Unit 4 i s d i f f i c u l t to distinguish from the chlorite-rich rocks of Unit 8, and because of this, some rocks which were mapped in the f i e l d as part of Unit 8 were later suspected as 56. representing c h l o r i t i z e d rocks of Unit 4. From what i s known, completely c h l o r i t i z e d rocks occur as small lenses and pods within mineralized horizons and t h e i r inclusion as part of Unit 8 does not appreciably affect the d i s t r i b u t i o n of Unit 8 l i t h o l o g i e s as mapped. Petrographically, d i s t i n c t i o n between completely c h l o r i t i z e d rocks and Unit 8 rocks i s based upon the amount of sphene present. Sphene, a major constituent of Unit 8, generally forms a minor part of c h l o r i t i z e d rocks. Secondary c h l o r i t e also occurs as small, ir r e g u l a r patches and as fine disseminations within and adjacent to areas of sulphide mineralization. Where c h l o r i t e i s f i n e l y disseminated, the rocks have a spotted green appearance (Plate 15). Secondary c h l o r i t e i s closely associated with mineralized veins and fractures and occurs as halos, laminations and disseminations adjacent to vein and fracture walls (Plate 16). Chlorite halos are less than \ inch to more than 2 inches wide. Chlorite laminations, which p a r a l l e l the f o l i a t i o n S^, normally are less than \ inch thick. Some c h l o r i t e disseminations have sulphide or a l b i t e cores (Plate 16). Paragenesis The sequence of deposition of primary minerals during the main period of mineralization i s shown i n Figure 11. On the basis of textures, cross-cutting relationships and r e l a t i v e timing with the t h i r d period of deforma-tion t h i s sequence was as follows: oldest carbonate sphene py r i t e c h l o r i t e molybdenite arsenopyrite magnetite pyrrhotite 57. folding fracturing py Mo Arseno Po Cpy Sph Carb Sphene Chi Mag Rutile Tour Qtz Ab Deformation Sulphide Deposition ? ? Oxide, Carbonate and Silicate Deposition Decreasing Age Fig 11. Sequence of deposition of primary minerals during the main period of mineralization. 58. chalcopyrite sphalerite quartz a l b i t e tourmaline youngest r u t i l e F i e l d relations suggest mineralization was continuous with the bulk of mineralization occurring before the large-scale development of tension fractures. Nonmineralized tension fractures adjacent to mineralized tension fractures suggest fracturing outlasted mineralization. Form of the Deposits Areas with greater than 0.2 weight percent copper over true thick-nesses exceeding 50 feet are outlined on Figure 4 and are shown on Sections I I , V and VI. The 0.2 weight percent cut-off serves as a natural demarca-t i o n because values outside these areas generally are an order of magnitude lower. Copper values within these areas are uniform and rarely exceed 1 weight percent over a true thickness exceeding 10 feet. Copper mineralization i s confined to tabular-shaped bodies which have an average east-west s t r i k e and a f a i r l y uniform northerly dip. The Main Mineralized Horizon (Figure 4) has a continuous s t r i k e length of more than 6000 feet and a true thickness of up to 400 feet. This zone has been ex-plored along i t s dip length for 2000 feet. More than 90 percent of the copper within these horizons was deposited during Stage I mineralization. Most of the remainder was deposited during Stage I I . Structural Controls The crenulation f o l i a t i o n was l o c a l l y important for the channeling of 'ore-forming* f l u i d s but does not appear to be responsible for the ov e r a l l d i s t r i b u t i o n of copper-bearing horizons. Large-scale structures appear to have had an important r o l e . One such structure i s the S-shaped f o l d located 59. near the center of the map-area and is illustrated in Figure 12, which i s a structure-contour map of the footwall of the main mineralized horizon. Copper mineralization does not appear to be deformed by this structure but rather appears to fan-out from this centrally located structure. The southern part of the main mineralized horizon east of the central flexure dips steeply (60 to 90 degrees) to the north and rapidly flattens towards the north to a more uniform dip of about 30 degrees north (refer to Figure 12 and Sections V and VI). This structure resembles the lower half of an isoclinal fold with an east-west axis orientation. The geometry of this structure i s anomalous and does not correlate with any previously discussed structures. Possibly there i s a relationship with the early foliation S^ . Stratigraphic Controls Copper mineralization does not appear to be stratigraphically controlled. The overall pattern of mineralization i s one of transgression. Surface traces of copper-bearing horizons have an average east-west orientation. Stratigraphic units have a prefered northeast-southwest orientation. A l -though copper-bearing horizons usually conform with stratigraphy down-dip (Sections V and VI) there are marked discordancies (Section I I ) . Although copper-bearing horizons do not appear to be stratigraphically controlled, stratigraphy was important in the locallization of higher grade zones. Unit 8 lithologies, notably chlorite: phyllite, appear to be the best hosts for copper mineralization. This relationship i s graphically illustrated in Figure 13. Titanium values, which also are graphically shown in Figure 13, i l l u s t r a t e a close correlation with lithologies. One exception 60. Fig 12. Structure Contour Map of the 'footwall' of the main copper-bearing horizon (contour interval equals 4 0 feet) Scale i 1 Inch Equals 400 Feet Fig 13 Graphical plot of a diamond-drill hole log ( D . D . H ) with corresponding titanium and copper values. 62. occurs near the bottom of the diamond-drill hole i n a c h l o r i t i c quartzite member which would probably have lower primary titanium values. Also evident i s a correlation of higher titanium values within members of Unit 8 with higher copper values. Second Period Sulphides deposited during the second period of mineralization are, i n approximate order of decreasing abundance: p y r i t e , chalcopyrite, pyrrhotite, sphalerite, galena, tetrahedrite-tennantite and bornite. These f i n e - to coarse-grained sulphides occur as disseminations and patches within quartz, carbonate and quartz-carbonate veins. The veins are % inch to more than 1 foot i n width and cut structures developed during the t h i r d period of de-formation. Vein walls l o c a l l y are s i l i c i f i e d with l o c a l development of bright green hydrothermal s e r i c i t e . Most vein carbonate i s dolomite although magnesite and c a l c i t e also were i d e n t i f i e d by X-ray techniques. Sulphur Isotopes Sulphur isotope data for sulphide samples collected within the present area of study i s made available i n an unpublished Master of Science thesis e n t i t l e d "Sulfide Deposition at Noranda Creek, B.C." by K.J. Kirkland (1971). The values obtained for p y r i t e and chalcopyrite appear i n Figure 14. A l l 34 values are given as J S (per mil) where: i S 3 4(%.) - S^ / S ^ s a r n p l e ) V 2 ( s t a n d a r d ) x 1 0 0 0 S J*/S J /(standard) 34 — S S = 0.00%o for t r o i l i t e from the Canon Diablo meteorite was used as a standard. Kirkland has interpreted the data as representing one period of 34 mineralization. From Figure 14 i t appears possible that there are two SS populations. The sulphur isotope analyses for chalcopyrite and pyrite from mineralized veins f a l l with the range of - 5% e to + 5°h>. Kirkland 1s descrip-tion of veins resembles veins from the second period of mineralization but he does not describe veins similar to those developed during the f i r s t period of mineralization. Disseminated chalcopyrite as well as pyrite and chalco-pyrite from tension fractures f a l l within the range of + 1%. to + 97« . Diffusion mechanisms cannot explain these differences. In his thesis, Kirkland states: "The mechanism of isotopic diffusion would produce 1 light' wall rock sulfides and relatively 'heavy' vein sulfides. This pattern i s the reverse of the pattern found at Noranda Creek so the diffusion mech-anism is not believed responsible for the overall sulfur isotope pattern found within the thesis area." A possible alternative to Kirkland*s interpretation is that vein sulphides had a different source of sulphur than disseminated sulphides or sulphides found 34 in tension fractures. Kirkland has demonstrated that SS values for vein sulphides appear to be zonally arranged with values decreasing towards the Baldy batholith. Such zoning is not apparent for disseminated sulphides or sulphides found in tension fractures. Genesis The following f i e l d relations help support a hydrothermal origin for the main period of mineralization at Harper Creek: 1) It appears that the main period of mineralization was synchronous with the third period of deformation. 2) Although stratigraphy i s important for the locallization of higher grade mineralization, the overall pattern i s one of transgression. 3) Stratigraphic units typically are discontinuous, whereas mineraliz-ed horizons display continuity (the main copper-bearing horizon Chalcopyrite Disseminated in siliceous phyllite Rn, n n 1 1 1 i n I I 1 Tension fractures n 1 1 n ni i I I in. n rn . 1 n n . I I I Veins n n i 1 1 I r - 6 - 4 - 2 0%o 2 4 6 8 Pyrite Disseminated in graphitic phyllite n 1 1 1 I I I I Disseminated in dyke n 1 1 1 I I I I Disseminated in quartzite n n n I I 1 I I I i Disseminated in phyllite and siliceous phyllite n n Fh n n n 1 1 1 n l I I I Veins m R r m n 1 1 1 1 1 1 1 - 6 - 4 - 2 0%, 2 4 6 8 Fig 14 tTS34values for pyrite and chalcopyrite; data from Kirkland, 1971, pp. 27-29. 65. has a continuous s t r i k e length of over 6000 fe e t ) . 4) Most sulphides display replacement textures. 5) Mineralization appears to post-date regional metamorphism thereby weakening arguments for remobilized syngenetic sulphide. 6) Sulphides deformed p r i o r to the t h i r d period of deformation were not observed. 7) Sulphides conforming to small-scale folds developed p r i o r to the t h i r d period of deformation were not observed. The main period of mineralization at Harper Creek does not appear to be genetically related to known intrusives within the area. The Baldy batho l i t h i s thought to post-date the deposit and there i s no apparent r e l a -tionship between mineralization and andesite dykes (Unit 9). An alternative hypothesis i s that mineralizing f l u i d s are of hydro-thermal metamorphic o r i g i n . The regional d i s t r i b u t i o n of 'Harper Creek-type' occurrences, as shown i n Figure 15, lends support to t h i s idea. A l l 'Harper Creek-type' occurrences are located on the limbs of an east-west oriented antiform (core of antiform occupied by the Baldy batholith) and occur near the contact between c h l o r i t e - b i o t i t e gneiss and rocks of the Eagle Bay Formation ( i e , near the b i o t i t e isograd). Formation of the antiform i s thought to have occurred during the t h i r d period of deformation and therefore i s synchronous with the main period of mineralization at Harper Creek. The following model i s suggested to account f o r the observed nature of the Harper Creek copper deposit and for the d i s t r i b u t i o n of 'Harper Creek-type' occurrences: 'Harper Creek-type' occurrences are genetically related to the formation of the large east-west oriented antiform situated south of the map-area. The deposits were formed by mineralizing f l u i d s of hydrothermal metamorphic o r i g i n which migrated into t h i s struc-ture and replaced favorable host rocks. The model presented to explain the b i o t i t e - a c t i n o l i t e zone i n rocks 6 6 . adjacent to the gneiss i s consistent with this hypothesis. In this model i t was suggested that the gneiss, which was s t i l l undergoing metamorphism, was folded and squeezed into cooler overlying strata resulting in the raising of isotherms with the partial readjustment of the contact rocks to the new temperature conditions. If this event occurred during formation of the antiform i t would support an hypothesis of hydrothermal metamorphic fluids rising into this structure. 1 mm 0 mm ' I I ' ' I L—l—1—1—I scale Photomicrograph showing sulphide (opaque mineral) occurring as replacements of carbonate porphyroblasts (center of photo-graph), p l a i n p o l a r i z e d l i g h t . 1 mm 0 mm scale Photomicrograph of part of a Stage II v e i n , p l a i n p o l a r i z e d l i g h t . Note that gangue minerals, which include dolomite (Dol), tourmaline (T) and c h l o r i t e ( C h i ) , are zonally arranged p a r a l l -e l to the vein w a l l . Also note that sphene (opaque mineral) appears to have replaced p h y l l i t e (P). 69. Plate 15 Photograph i l l u s t r a t i n g c h l o r i t e a l t e r a t i o n (dark specks) which imparts a speckeled appearance to some of the rocks. Width of specimen i s about lk, inches. 1 mm 0 mm I i i _ j i _ l i i i _ i I scale Plate 16 Photomicrograph showing c h l o r i t e a l t e r a t i o n associated with a Stage I I vein, cross n i c o l s . Chlorite replaces s e r i c i t e adjacent to vein wall (opaque on photograph). A l t e r a t i o n c h l o r i t e also occurs as disseminations adjacent to vein walls (opaque patches on photograph) with a l b i t e cores. Euhedral porphyroblasts i n vein are a l b i t e . Dark grey matrix surround-ing porphyroblasts i s vein c h l o r i t e . 70. Chapter VI POTASSIUM-ARGON AGE DETERMINATIONS Although tenuous, evidence presented e a r l i e r suggests that the t h i r d period of deformation and presumably the main period of mineralization occurred between Upper T r i a s s i c (Karnian or Lower Norian) and Lower Jurassic-Upper T r i a s s i c . Because metamorphism of the c h l o r i t e - b i o t i t e gneiss of Unit 10 appears to have continued into t h i s deformational period, three samples of gneiss were collected for potassium-argon age determinations. Samples were analysed by J.E. Harakal i n the K-Ar laboratory of the Department of Geological Sciences and the Department of Geophysics at the University of B.C. One sample of gneiss was collected south of the Baldy batholith about 5 miles east-southeast from the east end of East Barriere Lake. A second sample was collected approximately 5 miles west of the f i r s t . The t h i r d sample was collected at the headwaters of Foghorn Creek, approximately 4 miles west of the map-area. Samples selected contain l i t t l e or no c h l o r i t e . Sample Location 51° 17'N, 119°37'W 51° 17»N, 119° 42%'W 51° 31'N, 119956'W Table VII Potassium-Argon Age Determinations 40 40 Material K(%) Ar /K Apparent Age (m.y.) b i o t i t e 7.33 + 0.09 0.005884 98.0 + 3.8 b i o t i t e 7.01 + 0.03 0.007653 126 +4.0 Whole rock 1.19 + 0.007 0.005998 99.8 + 3.1 The r e s u l t s obtained are shown i n Table VII. Two samples gave ages of 71. 98 m.y. and 99.8 m.y. These dates correspond closely to the potassium-argon dates of 98 m.y. and 103 m.y. obtained by Kirkland (1971) and 80 m.y. and 96 m.y. obtained by the Geological Survey of Canada from rocks of the Baldy batholith. It seems probable that radiogenic argon in these samples was lost at the time of emplacement of this batholith. The third sample gave an apparent age of 126 m.y. The sample was taken approximately the same distance from the Baldy batholith as the sample which gave an apparent age of 98 m.y. and has possibly also lost some radio-genic argon during emplacement of the batholith. Although the date has probably been reset, i t can be considered as a minimum age for metamorphism of the gneiss. 72. Chapter VII CONCLUSIONS The following conclusions are based on observations and discussions presented in this study: 1) Mineralization occurs almost exclusively within metasedimentary and metavolcanic rocks of the Eagle Bay Formation. 2) Copper mineralization i s confined to tabular-shaped bodies which have an average east-west strike and dip f a i r l y uniformly to the north. 3) Age of the main period of mineralization i s between Upper Triassic (Kamian or Lower Noran) and Lower Jurassic-Upper Triassic. 4) Mineralization appears to post-date regional metamorphism of the host rocks. 5) The deposit appears to be genetically related to the formation of a large east-west oriented antiform located south of the map-area. 6) Large-scale structures within the antiform appear to have had an important role in the channeling of 'ore-forming' fluids. 7) 'Ore-forming' fluids are of probable hydrothermal metamorphic origin. 8) The host rocks are polydeformed and exhibit the effects of four periods of deformation. 9) The main period of mineralization appears to have been, in part, synchronous with the third period of deformation. 10) Although mineralization does not appear to be stratigraphically controlled, stratigraphy was important for the l o c a l i z a t i o n of higher grade mineralization. 11) Titanium-rich l i t h o l o g i e s appear to be the best host for copper mineralization. 12) A l t e r a t i o n of the host rocks during the main period of mineraliza-t i o n involved an early r e c r y s t a l l i z a t i o n of s e r i c i t e and c h l o r i t e formed by regional metamorphism and a l a t e r c h l o r i t i z a t i o n . 13) The contact between rocks of the Eagle Bay Formation and the c h l o r i t e - b i o t i t e gneiss (Unit 10) i s an important parameter for the occurrence of 'Harper Creek-type' occurrences. 14) The contact between the gneiss (Unit 10) and rocks of the Eagle Bay Formation may represent a faulted b i o t i t e isograd. 15) Metamorphism of the gneiss continued into the t h i r d period of deformation. 16) Most sphene i s of regional metamorphic o r i g i n but some occurs as hydrothermal replacements of carbonate. 74. REFERENCES Badgley, P.C., 1959: S t a t i s t i c a l Analyses of Structural Units by Sterio-graphic and Related Projections; i n S t a t i s t i c a l Methods for the Exploration Geologist, Harper Brothers publishers, pp. 214-223. , 1965: Structural and Tectonic P r i n c i p l e s , edited by C. Croneis; New York, Harper & Row, publishers. Campbell, R.B., 1964:. Adams Lake, B r i t i s h Columbia; Geol. Surv. Can., map 48-1963. Campbell, R.B. and Tipper, H.W., 1971: Bonaparte Lake map-area, B r i t i s h Columbia; Geol. Surv. Can., Mem. 363. Campbell, R.B. and Okulitch, A.V., 1973: Stratigraphy and Structure of the Mount Ida Group, Vernon (82L), Adams Lake (82M W%), and Bonaparte (92P) map-areas; i n Rept, of A c t i v i t i e s , Pt. A, A p r i l to October, 1972, Geol. Surv. Can., Paper 73-1, pt. A, pp. 21-23. Daly, R.A., 1912: Summary report on a reconnaissance of the Shuswap Lakes and v i c i n i t y , south-central, B.C.; i n Geol. Surv. Can., S.R., 1911, pp. 165-174. , 1914:, Geology of the Sel k i r k and Pu r c e l l mountains at the Canadian P a c i f i c Railway main l i n e ; i n Geol. Surv. Can., S.R., 1912, pp. 156-164. Dawson, G.M., 1895:; Report on the area of Kamloops map-sheet, B r i t i s h Columbia; Geol. Surv. Can., Ann. Rept. 1894, v o l . VII. Dawson, G.M., 1898:., Shuswap Sheet; Geol. Surv. Can., Map 604. Ernst, W.G., 1972:< C0 2-poor composition of the f l u i d attending Franciscan and Sambagawa low-grade metamorphism; i n Geochimica et Cosmochimica Octa, 1972, Vol. 36, pp. 497-504. Fyson, W.K., 1970:,, Structural relations i n metamorphic rocks, Shuswap Lake area, B r i t i s h Columbia; i n Structure of the Southern Canadian Cordilleran; Geol. Assoc. Can., Spec. Paper 6, pp. 107-122. Hutchinson, R.W. and Hodder, R.W., 1972: Possible tectonic and metallog-enic relationships between porphyry copper and massive sulphide deposits; i n CIM B u l l , for Feb., 1972, pp. 34-39.. Jensen, M.L., 1967: Sulfur Isotopes and Mineral Genesis; i n Geochemistry of Hydrothermal Ore Deposits, edited by H.L. Barnes, New York, Holt, Rinehard & Winston, Inc., pp. 143-165. Jones, A.G., 1959?, Vernon map-area, B r i t i s h Columbia; Geol. Surv. Can., Mem. 296. 75. Kerr, P.F., 1959: Optical Minerology, t h i r d edition; New York, McGraw-H i l l Book Co. Kirkland, K.J., 1971: Sulfide Deposition at Noranda Creek, B r i t i s h Columbia; unpublished M.Sc. Thesis, Dept. of Geology, University of Alberta. Meyer, C. and Hemley, J . J . , 1967: Wall Rock A l t e r a t i o n ; i n Geochemistry of Hydrothermal Ore Deposits, edited by H.L. Banes, New York, Holt, Rinehard & Winston, Inc., pp. 167-232. Nockolds, S.R., 1954: Average chemical composition of some igneous rocks; B u l l . Geol. Soc. Amer., Vol. 65, pp. 1007-1032. Osborne, W.W., 1967: Harper Creek area follow-up; unpublished report, Noranda Expl. Co. Ltd. Poldervaart, A., 1955: Chemistry of.the Earth's Crust; i n Crust of the Earth--a symposium, G.S.A., S.P. 62, pp.,133-136. Preto, V.A.G., 1970: Goof, Sue, H a i l ; i n Geology, Exploration and Mining i n B.C., B.C. Dept. of Mines & Pet. Res., pp. 297-301. Schouten, C , 1962: Determination Tables for Ore Microscopy; published by Elsevier Publishing Co. Schuiling, R.D. and Vink, B.W., 1967: S t a b i l i t y r elations of some titanium-minerals (sphene, perovskite, r u t i l e , anatase); i n Geochimica et Cosmochimica Acta, Vol. 31, pp. 2399-2411. Soregaroli, A., 1972: Harper Creek Jo i n t Venture-Summary Report for 1971, unpublished report Noranda Expl. Co. Ltd. S u f f e l , G.G., 1965: Remarks on some sulphide deposits i n volcanic ex-trusives; i n Can. Inst. Min. & Met., Trans., Vol. 68, pp. 301-307. Uglow, W.L., 1922: Geology of the North Thompson Valley map-area; Geol. Surv. Can., S.R., 1921-A. pp. 76-106. Walker, J.F., 1931: Clearwater River and Foghorn Creek map-area, Kamloops D i s t r i c t , B r i t i s h Columbia; i n Geol. Surv. Can., S.R., 1930-A, pp. 125-153. Wanless, R.K., Stevens, R.D., Lachance, G.R. and Rimsaite, J.Y.H., 1966: Age determinations and geological studies, K-Ar Isotopic Ages, Report 6; Geol. Surv. Can., Paper 65-17, pp. 16-17. Wanless, R.K., Stevens, R.D., Lachance, G.R. and Edmonds, CM., 1967: Age determinations and geological studies, K-Ar Isotopic Ages, Report 7; Geol. Surv. Can., Paper 66-17, pp. 25-26. Wanless, R.K., Stevens, R.D., Lachance, G.R. and Edmonds, CM., 1968: Age determinations and geological studies, K-Ar Isotopic Ages, Report 8; Geol. Surv. Can., Paper 67-2, pt, A, pp. 34-35. Westerman, C.J., 1968: Harper Creek Property, Geology; unpublished report, Noranda Expl. Co. Ltd. Williams, H., Turner, F.J. and Gilbert, CM., 1954: Petrography; San Francisco, W.H. Freeman & Co. Winkler, H.G.F., 1967: Petrogenesis of metamorphic rocks, revised second edition; New York, Springer-Verlag Inc. APPENDIX A No. 1 Name Description of mineral deposits within part of the Adams Lake and Bonaparte Lake map-areas Location Metals Copper King 51 31«N;119 55»W Cu (keystone Group) Foghorn (Lydia) Gopher Shamrock Rexspar 51° 32'N;1190 55'W Cu Description Bands, pods and disseminations of chalcopyrite i n schist Chalcopyrite as bands, pods and disseminations i n schist; some chalcopyrite as fracture f i l l i n g s 51 32'N;119°57'W Cu, Pb, Zn Mineralization reported to occur i n greenschist and quartz-51 32'N;119 55'W Pb 51° 34'N;119°54'W U, Mo, Pb, s e r i c i t e schist Quartz vein mineralized with galena Replacement body i n trachyte; rare earth's mineralization occurs as f l u o r i t e f l a t - l y i n g lenses conform-able with the enclosing schists Selected References 1924, p. 152 2 1916, pp. 221-222 1919, p. 179 1924, p. A152 1970, p. 302 1917, p. 236 1924, p. 152 1930, p. A 145 1949, pp. A250-A 255 1954, pp. 108-111 1957, pp. 31-32 1958, p. 30 1968, p. 164 1970, pp. 301-302 *for number locations refer to Figure 2. 2 unless otherwise indicated, references refer to Annual Minister of Mines Reports, B.C. Department of Mines. 6 Smuggler 51 7 Minnesota G i r l 51° 8 M i l l a r s Prospect 51° 10 Brenda, Sonja 51° 9 B u l l i o n 51° 11 Bearsden 51° 12 Tinkirk 51° 13 Red Top 51° 14 Trophy Mt. 51° (Summit) 15 Tim, AX, NX 51° 34'N; 119°54'W Ag, Pb, Mn 34'N; U9°54'W Ag, Pb, Zn 35'N; 119°54'W Pb, Zn, Mo 36'N; 119°52'W Pb, Ag, Au, Cu 35«N; 119°54'W U 37'N; 119°49'W Pb, Ag, Au, Cu 37'N; 119° 47'W Pb 38'N; 119°52'W Pb, Ag 49'N; 119°49'W Pb, Zn, Ag 49'N; 119°57'W Mo Si l v e r and lead mineralization 1925, p. B151 i n quartz veins 1926, p. 187 1927, p. 191 1930, pp. A192-A193 Mineralization occurs as 1924, p. 152 fissure f i l l i n g s 1926, p. 188 1930, p. 193 Quartz veins mineralized with G.S.C. galena and sphalerite; SR 1930 A, p. 143 minor molybdenite 1968, p. 163 Reported trachytic volcanic rocks 1968, p. 164 replaced by uraninite, pyrite 1969, p. 229 and f l u o r i t e Quartz vein i n schist 1969, p. 228 Quartz veins mineralized with 1969, p. 228 galena Lead and s i l v e r minerals found 1927, p. 191 i n seams i n a zone of shearing Sphalerite, galena with p y r i t e , 1956, pp. 69-70 pyrrhotite and minor chalco- 1969, p. 230 pyrite occur as conformable lenses i n quartz-biotite gneiss 1968, p. 166 16 Mo1cop 51° 48»N; 119° 23'W Mo, Cu 17 ESP 18 H i l l t o p 19 P o l l y Ann 20 H,M 21 Barriere 22 Harper 23 S i t t i n g B u l l 24 White Rock 51° 36«N; 119'36'W Cu 51° 29»N; 119°37'W Cu 51° 23'N; 119°52'W Mo 51° 22'N; 119°51'W Mo 51° 20«N; 119#44»W Cu, Zn 51° 20«N; 119°52'W Cu, Pb, Zn 51° 20»N; 119°52'W Cu 51° 18«N; 119°53»W Ag, Pb, Zn Coarse molybdenite i s found i n 1970, p. 296 pegmatitic rocks; the pegmatites occur as pods and .'discontinuous veins i n Shushwap gneiss; chalco-p y r i t e with minor molybdenite also occur as disseminations i n acidic dykes Chalcopyrite reported to occur 1970, p. 296 as disseminations and con-formable lenses i n c h l o r i t e and quartz-sericite schists Horizon of sporadic copper mineral-i z a t i o n i n greenstone Molybdenite occurs i n a set of 1964, p. 99 widely spaced quartz veins 1967, p. 134 Chalcopyrite i n c h l o r i t e schists; 1969, p. 233 mineralization i s similar i n 1970, p. 314 some respects to that found at "Harper Creek" Reports of chalcopyrite, galena 1962, pp. 60,61 and sphalerite i n schist 1963, p. 59 Quartz seams mineralized with 1922, p. N146 chalcopyrite Series of quartz veins and frac- 1927, pp. C188, C189 tures mineralized with galena 1928, p. 212 and tetrahedrite; some apprec- 1950, p. A l l l iable s i l v e r values reported vO 25 OK Group 26 Rainbow 27 28 Birmoly 29 Kuno 30 North Star (north) 31 North Star (south) 32 Renning No. 1 (June) 33 Kajun 34 Renning, G r i z z l y , Cu 51° 19'N; 119°56«W 51° 20'N; 51° 20»N; 51° 22'N; 51° 22'N; 51° 22'N; 51° 21«N; 51° 15'N; 51° 16'N; 51° 17'N; 119*55'W 119° 54'W 119° 56'W 119°58'W 119°59'W 119°59«W 119° 48'W 119° 46'W 119° 45'W Pb, Zn, Ag Pb, Zn, Ag Cu, Zn Mo Ag, Pb Pb Pb, Zn, Ag Au Zn, Pb, Cu Pb, Zn, Cu Cu Dolomitic beds i n c h l o r i t e schist; 1927, pp. C188, C190 dolomites " p y r i t i z e d " and con- 1928, p. C211 t a i n some lead, zinc and copper minerals Descriptions of lead-zinc "re- 1927, pp. C188, C190 placement" bodies i n schist 1928, p. C211 Reported occurrence of chalco-py r i t e and sphalerite i n c h l o r i t e schists Molybdenite occurs as disseminationsl969, p. 232 i n an acid intrusive White quartz with a pocket of high 1927, pp. C188, C190 grade s i l v e r - l e a d ore Limestone and quartzite with 1927, pp. C190-C191 pyr i t e and galena 1935, pp. D7-D8 1936, pp. D36-D39 Quartz veins with patches of 1927, pp. C190-C191 sphalerite and pyrite 1935, pp. D7-D8 1936, pp. D36-D39 Lead-zinc-copper sulphide body i n 1961, p. 48 crest of small recumbent f o l d 1968, p. 168 Er r a t i c splashes and veinlets of galena, with some chalcopyrite and sphalerite, i n schist Chalcopyrite disseminated i n 1969, p. 233 metasedimentary rocks 35 Bex 51° 36 S i l v e r Mineral 51° 37 Rose Group 51° 38 Max, Hope 51° 39 Homestake 51° 40 Joe, Art 51° (Douglas and Lower Six) 41 Try Me and 51° Ranking Group 42 Acacia 51° 43 New Gem and 51° Discovery Group 17»N; 119°43'W Cu 17'N; 119'54'W Ag, Pb 08«N; 119'41'W Zn 08»N; 119°47'W Pb, Zn, Ag 07«N; 119°49«W Ab, Ba 05'N; 119°45»W Pb, Zn, Ag, Cu 05'N; 119°45'W Pb, Zn, Cu 05'N; 119°50'W Pb, Zn 05«N; 119°51tW Pb, Zn Chalcopyrite i n quartz-biotite 1967 schist 1968 1969 Reports of good-grade s i l v e r - 1927 lead ore i n veins 1928 Sphalerite, as fissure f i l l i n g s , 1916 in limestone 1918 Dolomitic rocks, conformable to 1936 the enclosing schists, are 1953 mineralized with galena and 1969 sphalerite Barite vein with s i l v e r , t e t r a - 1918 hedrite, galena and minor 1923 chalcopyrite; vein conformable 1926 with enclosing schists 1936 1964 Outcrops of s i l v e r - l e a d ore occur 1930 i n association with barite and 1966 i n quartz veins Very low-grade lead-zinc-copper 1924 mineralization occurs i n quartz 1961 and quartz-carbonate veins i n schist p. 134 p. 169 p. 233 pp. C188-C189 p. 212 pp. K219-K220 p. 236 p. D39 p. 101 p. 234 pp. 221-223 pp. 147-148 pp. 185, 186 pp. D32-36 p. 99 p. A189 p. 145 p. B157 pp. 53-55 Two seams (4in.-8in. i n width) of 1926, p. A186 lead and zinc sulphide lying con-formably with the formation 1926, p. A186 44 Tom, Glen 51° 04'N; 119°42'W Pb, Zn, Ag, (Rhode Island Cu Lead Co.) 45 Elmoore 51° 04'N; 119°41'W Pb, Ag, Zn, (Lincoln, Cu Wallace) 46 Lucky Coon, 51° 04'N; 119°38'W Pb, Zn, Ag E l s i e and White Swan 47 Speedwell, 51° 06'N; 119°34'W Zn, Pb, Ag King Tut, Donnamore 48 EX 51° 03'N; 119°33'W Zn, Pb (Mosquito King) 49 Mosquito King 51° 03'N; 119°31'W Zn, Pb, Ag 50 51° 32'N; 119°44'W Pb, Cu 51 Dunn 51° 25'N; 120°01'W Mo 52 Mike, Marge 51° 06'N; 119°22'W Ag, Pb, Zn Occurrence of lead-zinc ore i n a zone of fracturing about 100' wide Breccia zone mineralized with galena, sphalerite and minor chalcopyrite Series of mineralized seams lying conformable with the schists of Shuswap series Bands of lead and zinc sulphide i n schist Pyrrhotite, p y r i t e , sphalerite and galena occur i n the f o l i a t i o n of sch i s t s , and are further l o c a l i z -ed i n minor crumples Bands of sulphide i n schist Thin seam of galena, with minor cpy, i n limestone Molybdenite i n quartz veins and fractures Two beds mineralized with p y r i t e , galena and sphalerite i n s e r i c i t e s c h i s t , limestone and altered limestone 1926 1967 1928 1934 1936 1966 1927 1930 1936 1930 1934 1936 1953 1967 P< P« A186 134 p. C210 pp. D28-D29 p. D43 p. 145 pp. C199-C200 pp. A184-A185, A187 pp. D39-D43 pp. A185-A187 p. D28 pp. D40, D43 pp. pp. A102-A103 134-135 1930, pp. A186-A188 1936, p. D40 1960, p. 318 53 Bet, Saul 51° 03»N; 119°15'W Ag, Pb, Zn (venus) 54 Py Group 51° 30»N; 119°52'W Cu 55 AJS 51° OO'N; 120°26'W Mo, Cu 56 PC 51° 12'N; 120°14'W Cu 57 A l l i e s 51° 18'N; 120°12'w Pb, Cu 58 LK 51° 19'N; 120°06'W Cu 59 Windpass 51° 27'N; 120°05'W Au 60 Hidden Creek, 51° 27»N; 120°17'W Cu, Ag, Au 61 Queen Bess 51° 32'N; 120°08'W Ag, Pb, Zn 62 Jan, T.C. 51° 30'N; 120°23'W Cu Silver-lead-zinc ore found i n seams 1930, p. A188 cutting limestone 1931, pp. A105-A106 1964, p. 99 Chalcopyrite, pyrite and pyrrhotite i n schist Hornblende tonalite mineralized withl969, p. 234 chalcopyrite, molybdenite and pyrite Complex pluton mineralized with 1970, p. 316 chalcopyrite Disseminated p y r i t e , galena and G.S.C., chalcopyrite i n quartz veins S.R., 1921, pp. 100A-101A P y r i t e , chalcopyrite and magnetite 1970, p. 313 found i n rocks of the Fennell Formation Gold and gold t e l l u r i d e s i n a G.S.C., Mem. 363, quartz vein which cuts a pyroxen- p. 86 i t e s i l l of the Fennell Forma-ti o n Gold, s i l v e r and copper values 1968, p. 168 reported to occur i n gr a n i t i c 1970, p. 313 rocks of the Thuya Batholith Veins, mineralized with galena and 1919, pp. K234-K236 sphalerite, occur i n greenstone 1951, pp. 125-128 of the Fennell Formation Mineralization reported to occur as fracture f i l l i n g s i n d i o r i t i c and volcanic rocks 1966, p. 143 1967, p. 132 63 RO, SO, TC, RI;. LO (Friendly Lake) 51° 35'N; 120°27'W Cu, Mo, Ag, Pb 64 Silver 51° 35'N; 120°26'W Cu, Zn 65 Anticlimax 51° 35'N; 120°18'W Mo (Tintlhohtan Lake) 66 Empire and 51° 40'N; 120° 02'W Pb, Zn Bluebird 67 Sonja 51° 38'N; 120° 00' W Ag, Pb, Zn, Au, Cu 68 Polly Ann 51° 43'N; 120*03'W Mo 69 Jud, Rex, Ax, 51° 48'N; 120°01'W Mo Ab, T i , Nx 70 Wet, Sun, Aku 51° 47'N; 120°24'W Mo 71 CS 51° 48'N; 120°25'W Mo 72 CL, OX 51° 50'N; 120°25'W Mo Disseminated argentiferous galena 1968, pp. 167-168 occurs within a shear zone; highly fractured andesite breccias contain disseminated pyrite and chalcopyrite Skarn with pyrrhotite, pyrite, mag- 1968, pp. 166-167 netite, chalcopyrite and sphalerite Molybdenite is found in thin quartz 1961, pp. 49-51 veinlets in a small granite stock 1965, p. 160 1970, pp. 304-307 G.S.C., Mem. 363, p. 85 Galena and sphalerite in quartz 1934, p. D26 veins in schist 1969, p. 230 Molybdenite in a set of widely 1964, p. 99 spaced quartz veinlets Molybdenite in Shuswap gneisses 1967, p. 131 Quartz veins, with molybdenite, 1967, p. 131 in quartz monzonite 1968, p. 166 Quartz fractures, with molybdenite, 1970, p. 303 in granodiorite 1968, p. 165 73 Foghorn 51° 32'N; 119°57'W Ag, Pb, Zn, Cu 74 VM 75 Sands Creek 76 Barriere East 51° 31'N; 119°42»W Cu 51° 40«N; 120°03'W Mo 51° 17'N; 119°37'W Cu Galena and sphalerite are found as 1913, p. 212 fiss u r e f i l l i n g s 1915, p. 211 1916, pp. 266, 518 1917, pp. 236, 450 1924, p. 150 G.S.C., S.R., 1930 A, p. 143 Reports of chalcopyrite dissemin- 1970, p. 297 ated i n schist Molybdenite, p y r i t e , magnetite and 1961, pp. 51-53 scarce chalcopyrite i n quartz veins and pegmatitic dykes Disseminations of chalcopyrite i n Gneiss 8 6 . APPENDIX B Description of samples used For K-Ar age determinations Barriere East Property Sample i s from recent road cut about 5 miles east southeast from the east end of East Barriere Lake. The rock contains approximately 45 percent a l b i t e , 20 percent b i o t i t e , 15 percent epidote, 10 percent quartz and minor sphene. About 1 percent of the a l b i t e , which occurs as anhedral t i g h t l y interlocking grains, i s twinned. Alignment of fresh b i o t i t e imparts a good f o l i a t i o n to the rock. Fine-grained epidote occurs evenly disseminated. BEX Property Sample was taken from diamond-drill core located on the BEX property (about 5 miles west of the f i r s t sample). The rock i s the same as the sample taken from the Barriere East Property. Foghorn Property Sample i s of core collected at the headwaters of Foghorn Creek (approximately 4 miles west of the map-area). The rock contains approximately 45 percent a l b i t e , 20 percent s e r i c i t e , 10 percent carbonate, 10 percent quartz, 7 percent b i o t i t e , 5 percent c h l o r i t e , 3 percent epidote, 2 percent opaques and minor sphene. Chlorite and s e r i c i t e appear to occur as an a l t e r a t i o n of b i o t i t e . Carbonate occurs i n matrix and as vein f i l l i n g s . SECTION I Legend Unit Unit Quartto-reldspathic phyllite; minor lr» ' light green laminated greenstone Graphitic and carbonaceous phyllita; minor dolomite 6a Orthoquartlita. lericite quaniite albita-saricite quartziw 6a Carbonacaoua quartilra 1 2 Foliated, fragment al greenstone Osorite phyllita Chlorite phyllita. quarti-chor.le-saricite phytlrta. chkxita-aartetM phyllita: minor chlorite querulre Chlorite p h y i l r t a White to light green, well-roliaied. lustrous phyllita) scale: 1 inch equals 200 feet DWnond drill hole (win- acat mn) DtJmond drill hole (wrmout aoorrm) 8.800 E i I. MOO' 4 5 6 7 6 9 5600' 6400' 5 2 0 0 ' 5 0 0 0 ' 4 6 0 ? ' 4 6 0 0 ' . 1400' II 12 13 S E C T I O N II Legend Unit Graphitic and carbonaceous phylliti minor dolomite Quaruo-reldspethic phyllite; minor light green laminated greenstone 6a Orthoquartiite. sericite quarti albite-sericite quartzite 6b Carbonaceous quartrlla Foliated, fragmental greenstone Chlorite phyllite Chlorite phyllite. quartz-chloriie-senclie phyllite. chbute-senate phyllite. minor chlorite quartiita Chlorite phyllite A H n o d indaaiH White to light green, well-roliated. lustrous phyllite scale. 1 inch equals 200 feet DWnond drill hole acio nm) 7 n I ' Diamond drill hole (WIIMOUI AOO nm) to II Diamond drill core with greate weight percent copper 58 OO' S E C T I O N IV 5 6 0 0 ' / | ~j | Whrto io lighl green, w e l l -foliated, lustrous proline scale: 1 inch equals 200 feet CWnond drill hole IWIIH ACID run) 7 n ' 1 CKlmond drill hole IWIIMOUI ACID IIIMI 1 2 , 0 6 0 E z o o N 01 I 5 8 0 0 ' 4400 ' D i a m o n d d r i l l h o l e UHM MIO m n l 7 n I j Diamond drill hole (wit 10 II Diamond dull core with greater than 0 . 2 weight percent copper 4. G e o l o g y m a p o f t h e H a r p e r c r e e k c o p p e r d e p o s i t L e g e n d Unit Quartzo-feldspathic phyllite; minor light green, laminated greenstone Unit 6a Orthoquartzite, sericite quartzite, albite-sericite quartzite 6b Carbonaceous quartzite Foliated, fragmental greestone chlorite phyllite Dark green, fragmental phyllite Chlorite phyllite Chlorite phyllite, quartz-chlorite-sericite phyllite, chlorite-sericite phyllite; minor chlorite quartzite White to light green, well-foliated, lustrous phyllite 9 Altered andesite Graphitic and carbonaceous phyllite; minor dolomite 10 Chlorite-biotite gneiss / / / / / / / Schis tos i ty Early fold ax i s Late fold ax is (kink or open fold) W r i n k l e l ineat ion K i n k fo ld a^tis p lane Fracture ( i n c l i n e d ) Fracture ( ve r t i ca l ) Q u a r t z vein Outcrop Suboutcrop Geo log ic boundary ( infered) Fault ( in fered) A c c e s s road 31Q D r i l l hole l o c a t i o n B u i l d i n g 5600 E levat ion contour ( i n f e e t ) A r e a w i t h greater than 0.2 we ight percent copper Scale : 1 inch equals 400 feet 

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