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Geology, mineralization and alteration of the battle zone, Buttle Lake camp, central Vancouver Island,… Robinson, Michelle 1994

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GEOLOGY, MINERALIZATION AND ALTERATION OF TIlE BATTLE ZONE,BUTTLE LAKE CAMP, CENTRAL VANCOUVER ISLAND, SOUTHWESTERNBRITISH COLUMBIAbyMICHELLE ROBINSONBASc, The University ofBritish Columbia, 1992A THESIS SUBMITTED IN PARTIAL FULFILLMENT OFTHE REQUiREMENTS FOR THE DEGREE OFMASTER OF APPLIED SCIENCEinFACULTY OF GRADUATE STUDIES(Department of Geological Sciences)We accept this thesis as conforming4iretdar4THE UNIVERSITY OF BRITISH COLUMBIA27 April 1994© Michelle Robinson, 1994In presenting this thesis in partial fulfilment of the requirements for an advanceddegree at the University of British Columbia, I agree that theLibrary shall make itfreely available for reference and study. I further agree that permission for extensivecopying of this thesis for scholarly purposes may be granted by the head of mydepartment or by his or her representatives. It is understoodthat copying orpublication of this thesis for financial gain shall not be allowed without my writtenpermission.(Signature)Department of c1 OLjCUThe University of British ColumbiaVancouver, CanadaDate 29 /q’DE-6 (2188)ABSTRACTVolcanogenic massive suiphide deposits within the Buttle Lake mining camp are associatedwith andesitic and felsic rocks of the Price and Myra formation in the Paleozoic Sicker Group.The Battle zone occurs within H-W horizon, the lowest member of the Myra formation. H-Whorizon is a 15 to 200 m thick felsic package that occurs throughout the camp, immediately abovethe Price andesite, which is the lowest known unit within the Sicker Group in the Buttle Lakearea. H-W horizon consists of seven members, two of which represent periods of massivesulphide deposition. From the stratigraphic base to top these members are: Battle and Gap zonemassive suiphide lenses, fine rhyolitic tuffaceous deposits, H-W mafic sills, coarse rhyolitepyroclastic deposits, rhyolite tuffaceous sediments, upper zone massive suiphides, and the rhyoliteflow-dome complex.Thin section petrography and Pearce element ratio analysis of lithogeochemical data fromsamples of least altered rocks from the Price formation and rhyolite flow dome complex supportthe following conclusions: (i) lavas in the Price andesite are comagmatic and are related bysorting of plagioclase feldspar, pyroxene, olivine and Fe-Ti oxides, and (ii) the quartz porphyriticrhyolite (QP), quartz feldspar porphyritic rhyolite (QFP) and green quartz feldspar porphyriticrhyolite (GQFP) units of the rhyolite flow dome complex are comagmatic and are related bysorting of quartz and feldspar.Alteration in the Battle zone is marked by addition of silica in both the footwafi andimmediate hangingwall. A signfficant amount of iron in the form of stringers and disseminatedpyrite has also been added in the footwall. A broader zone dominated by sericite alteration thatoccurs both above and below the orebody corresponds to loss of sodium and calcium, andaddition of potassium, barium and rubidium. Magnesium does not show any systematic spatialtrends that clearly are related to hydrothermal alteration.IIThe first cycle of mineralization was the most voluminous, and formed main Battle massivesuiphide lens, the H-W main lens and probably the Gap lens. The main Battle massive sulphidelens is localized in a fault-bounded basin developed in the Price formation andesite. From alaterally extensive footwall stringer zone, it varies upwards through: (i) massive pyrite andchalcopyrite, (ii) banded massive suiphide in the central region, to (iii) pale yellow massivesphalerite at the top and periphery. This zonal distribution appears to have formed by a processof progressive zone replacement as a result of continued reaction between upweffing fluid andpreviously deposited suiphides. A second cycle of upper zone mineralization is represented bysmall, discontinuous lenses of baritic sphalerite and tetrahedrite rich massive sulphide lenses abovethe rhyolite tuffaceous sediments.Galena lead isotope data from the Buttle Lake mining camp indicate that lead evolved inan orogene or island arc environment. The linear trend in the galena lead data can be explained asa mixing line. Positions of data along this trend do not relate to age differences among the orelenses, but appears to represent either: (i) varied mixing of upper crustal and mantle components,as might be expected in an orogene or island arc environment, or (ii) variable selective leaching oflead isotope components from footwall source rocks. A combination of these processes is notexcluded. The less radiogenic end member appears to be spatially related to rhyolitic host rocks.The more radiogenic deposits occur immediately above major discharge stockworks in andesite.In H-W horizon, markedly radiogenic lead is characteristic of deposits that define the main lenstrend (i.e. the H-W and Battle main lenses). Lenses in the main trend are among the largest;consequently a more radiogenic lead isotopic composition may identify favourable explorationtargets.ifiTABLE OF CONTENTSABSTRACT.iiACKNOWLEDGMENTS viiCHAPTER!. iNTRODUCTION 11.1 HISTORY1.2SCOPEOFTHESISCHAPTER 2. REGIONAL AN]) MiNE GEOLOGY 92.1 REGIONAL GEOLOGY q2.2 MINE GEOLOGY: THE MYRA FORMATION2.2.1 Lithology IZ2.2.2 Structure2.2.3 MetamorphismCHAPTER 3. GEOLOGY OF THE BATTLE ZONE3.1 INTRODUCTION3.2 LITHOLOGY 243.2.1 Price formation3.2.2 H-W horizon3.2.2.1 Battle and Gap zone massive suiphide lenses 12..3.2.2.2 Fine rhyolitic tuffaceous deposits 313.2.2.3 H-W mafic sills 32.3.2.2.4 Coarse rhyolite pyroclastic deposits 32.3.2.2.5 Rhyolitic tuffaceous sediments 333.2.2.6 Upper zone massive suiphide lenses 3(43.2.2.7 Rhyolite flow-dome complex3.2.3 Hangingwall andesite 39Iv3.2.4Dikes.3.3 INTERPRETATION: BATTLE AND GAP ZONE GEOLOGY3.3.1 Introduction3.3.2 Evolution of massive suiphide lenses3.3.3 The origin of chert: exhalite or volcanic? Si3.3.4 Rhyolite volcanic sequenceCHAPTER 4. PRIMARY IGNEOUS LITHOGEOCHEMISTRY 71)4.1 INTRODUCTION 704.2 METHODOLOGY AND ANALYTICAL ERROR4.3 ROCK CLASSIFICATION AND MAGMATIC AFFiNITY 714.3.1 Mafic rocks4.3.2 Felsic rocks4.4 ROCK-FORMING PROCESSES4.4.1 PER analysis ofPrice andesite4.4.2 PER analysis of the rhyolite flow-dome complex 9°CHAPTER 5. ALTERATION ‘N5.1 INTRODUCTION ‘N5.2 ELEMENT BEHAVIOUR Ill5.2.1. Ti versus Zr liz5.2.2 Rare earth elements us5.3 FOOTWALL ALTERATION: PRICE FORMATION S5.3.1 Hand specimen and thin section description P 155.3.2 Chemical patterns I 2.15.4 HANGINGWALL ALTERATION: H-W HORIZON R}{YOLITE 1335.4.1 Hand specimen and thin section description 1335.4.2 Chemical patterns 133V5.5 MICROPROBE RESULTS .15.6 SUMIvIARY AND SPATIAL DISTRIBUTION OF ALTERATION1 L7CHAPTER 6. MASSIVE SULPHIDE LENSES: BATTLE GAP AND UPPER ZONES 1556.1 iNTRODUCTION 16.2 METHODOLOGY 1566.2PETROGRAPHY6.2.1 Main Battle zone massive suiphide lens 166.2.2 Gap massive suiphides I 7146.2.3 Upper zone massive suiphides 1E2.6.3 MICROPROBE RESULTS 1 2.6.4 INTERPRETATION OF SULPHIDE TEXTURES 1S6.4.1 Descriptive interpretation 16.4.2 Progressive zone replacement: a textural interpretation ICHAPTER 7. GALENA LEAD ISOTOPES, BUTTLE LAKE MINING CAMP t’137.1 INTRODUCTION7.2 ANALYTICAL TECHNIQUES A1J1) ERRORS 2(X)7.3 CHARACTERISTICS OF THE GALENA LEAD ISOTOPES 2007.3.1 Characterization as orogene lead 2. tb7.3.2 Linear array of galena lead isotope data 2O37.3.3 Definition of clusters and end members 2O7.3.4 Relationships among lenses, host and footwall rocks 2067.4 DISCUSSION 2157.4.1 Orogene or island arc characteristics 2 f7.4.2 Lack of age constraint by galena lead isotope data 217.4.3 Implications of upper crust - mantle mixing model 2177.4.4 Implications of selective leaching model Z18VI7.4.5 A genetic model for mineralization in the Battle/Gap zones .... 2 ISCHAPTER 8. CONCLUSIONS 2268.1 INTRODUCTION 22.58.2 STRATIGRAPHY 2a58.2.1 Lithology and stratigraphic sequence 2.2..8.2.2 Lithogeochemistry 2198.3 ALTERATION 2 Z’)8.4 MASSIVE SULPHIDE LENSES ANI) METALLOGENY 2318.4.1 Massive suiphide lenses 23g8.4.2 Metallogeny and lead isotopes 233REFERENCES 2 .5APPENDIX A. Lithogeochemical sampling and errors 2 Lf7APPENDIX B. Additional sulphide analyses from the Gap lens 2VIILIST OF FIGURESFigure 1.1.Figure 1.2.Figure 2.1.Figure 3.1.Figure 3.2.Figure 3.3.Figure 3.4.Figure 3.5.Figure 4.1.Figure 4.2.Figure 4.3.Figure 4.4.Figure 5.1.Figure 5.2.Figure 5.3.Figure 5.4.Figure 5.5.Figure 5.6.Figure 5.7.Figure 6.1.Figure 6.2.Figure 6.3.Figure 6.4.Figure 6.5Figure 7.1.Location map of the Buttle Lake mining camp 2.Surface and vertical projections of major orebodies ‘-1Schematic cross-section of the Myra Formation isStratigraphic columns of H-W horizon 23Cross-section of the Battle zone, 13+72E 25Cross-section of the Battle zone, 15+85E Z7Cross-section of the Battle zone, 17+98EDepositional model for H-W horizon in the Battle zoneGeochemical discrimination diagrams 75Conserved element scatterplotsPearce element ratio diagrams for the Price andesitePER assemblage test diagrams for rhyolite flowsPlot of Ti02 versus Zr for the Battle zone Il 3Rare earth element plots for the Price andesite and rhyolite i I b(2Ca+Na+K)/Zr PER versus Al/Zr PER for the Price andesite 122.Pearce element ratio (PER) diagrams Price andesite data 12.5(2Ca+Na+K)/Zr PER versus Al/Zr PER for rhyolite data 131Pearce element ratio (PER) bubble plots for rhyolite data )3.Diagram of the alteration zone for Section 15+85E I’49Composition of the various lens typesCross-section of the main Battle massive sulphide lens 15qDrill hole log of metal ratios in the main Battle lens kt2..Drill hole log of metal ratios in the Gap lens 17,6Idealized progressive recrystallization textures iiButtle Lake mining campyffiFigure 7.2. Diagrammatic cross-section of the Buttle Lake campFigure 7.3. Large scale galena lead isotope plots ZOFigure 7.4. Small scale galena lead isotope plots 21 bFigure 7.5. Galena lead plot of 2O8Pb/2O6Pb versus 2O7Pb/2O6Pb ZJ2..Figure 7.6. Evolution of mineralization in the Battle and Gap zones ZZ2IxLIST OF PLATESPlate 3.1. Price formation.41Plate 3.2. Main Battle massive suiphide lensPlate 3.3. Gap massive suiphide lens ‘Plate 3.4. Fine rhyolitic tuffaceous deposits 43Plate 3.5. H-W mafic sill 43Plate 3.6. Coarse rhyolite pyroclastic depositsPlate 3.7. Rhyolite tuffaceous sedimentsPlate 3.8. Upper zone massive suiphide lensesPlate 3.9. Rhyolite flow-dome complex 45Plate 3.10. Hangingwall andesite 47Plate 3.11. Feldspar quartz hornblende rhyolite porphyry dikePlate 5.1. Alteration facies within the Price formation andesite 119Plate 5.2. Alteration facies of the H-W horizon rhyolite J3LjPlate 6.1. Footwall stockwork mineralization IL,Plate 6.2. Chalcopyrite-rich massive suiphidePlate 6.3. Banded massive sulphide I7oPlate 6.4. Pale yellow massive sphalerite I 7Z.Plate 6.5. Bedded massive sulphide lizPlate 6.6. Pyritic massive sulphide, Gap zonePlate 6.7. Baritic massive sulphide Gap zonePlate 6.8. Upper zone massive suiphidexLIST OF TABLESTable 1.1. Proven and probable geological reserves 1Table 2.1. Table of formations for the Paleozoic Sicker Group 10Table 3.1. Mineralogy of members within the rhyolite flow-dome complex 3Table 4.1. Geochemical analyses of least-altered rocks 72..Table 4.2. Summary of Pearce element ratios for the Price andesiteTable 5.1 Major and trace element data for the Price andesiteTable 5.2 Major and trace element data for chert 101Table 5.3 Major and trace element data for the pumiceous lapilli tuff IozTable 5.4 Major and trace element data for the rhyolitic tuffaceous sediments.... 103Table 5.5 Major and trace element data for the H-W mafic sill 1 oqTable 5.6 Major and trace element data for the quartz porphyritic rhyolite 1 0Table 5.6 Major and trace element data for the hangingwall andesite 110Table 5.8. Trace and rare earth element data for selected rocks illTable 5.8 Electron microprobe analyses of sericite in the footwall 1 4Table 5.8 Electron microprobe analyses of sericite in the hangingwall ILl l?Table 6.1 Electron microprobe analyses for renierite 183Table 6.2 Electron microprobe analyses for colusiteTable 7.1. Galena lead isotope data for orebodiesTable 7.2. Calculated slopes for lead isotope plots to test model conceptsTable 7.3. Average galena lead isotope ratios for ore lenses 2O’Table 7.4. Horizon and host rock affiliations with ore lenses 209Table A. 1. Detection limits and analytical methods 2 Lf9Table A.2. Duplicate analyses of MDRU standards 25oTable A.3. Duplicate analyses of rock units 2 6qTable B. 1 Microprobe analyses for sulphides, Gap massive sulphide lens 257XIACKNOWLEDGMENTSI thank C. Godwin and A. Sinclair for their supervision over the last year and a half. WestminResources Limited provided access to company data and a wonderful working environment. Thegeologists at the H-W mine -- particularly S. Juras, C. Pearson, F. Bakker and I. McWilliams arethanked for their support and ideas. Early work by G. Price and A. Hamilton contributedsubstantially to this study. J. Thompson, R. Sherlock and other members of the Mineral DepositResearch Unit (MDRU) provided helpful discussions and insight. R. Allen offered superb adviceon the interpretation of some of the volcanic textures. T. Barrett and C. Stanley gave adviceinterpreting the lithogeochemistry. T. Brown and K. Russell reviewed and corrected much of thismanuscript. M. Raudsepp was especially helpful with the electron microprobe. A. Toma crushedsome of the whole-rock samples, and Y. Douma prepared many of the thin sections. Funding toM. Robinson was provided by Westmin and IVIDRU. This study is part of the VolcanogenicMassive Sulphide project undertaken by the MDRU at UBC, funded by the Natural Sciences andEngineering Research Council of Canada, the Science Council of British Columbia, and tenmining and exploration member companies. These industry partners include: Grange Inc.,Homestake Canada, Inc., Inco Exploration and Technical Services Inc., Kennecott Canada Inc.,Lac Minerals, Metall Mining Corporation, Placer Dome Limited, Teck Corporation and WestminResources Limited (industry project leader).XIICHAPTER 1INTRODUCTIONButtle Lake mining camp (NTS: 092F12E; 49°34’ north, 125°36’ west), near centralVancouver Island, in Strathcona Park at the south end ofButtle Lake, is 90 km southwest ofCampbell River, British Columbia (Figure 1.1). It is a major volcanogenic massive suiphidedistrict in which deposits are in the Myra formation of the Paleozoic Sicker Group. Pastproduction has come from several mines: Lynx open pit, Lynx underground mine, Myra open pitand H-W underground mine. The Price deposit, discovered early in the history of the camp, hasreceived sporadic work but has not been mined. Current production is from H-W mine. Between1966 and 1992, 13.8 million tonnes of ore grading 1.9 % copper, 5.6 % zinc, 0.6 % lead, 2.2grams gold per tonne and 64.0 grams silver per tonne had been mined from the camp (WestminAnnual Report, 1992). Of this, 7.5 million tonnes are from H-W, 5.3 million tonnes are fromLynx and 1.0 million tonnes are from Myra mine (Pearson, 1993). Geological reserves as of 1992are in Table 1.1 and total more than 12 million tonnes. Exploration within the camp has alsodefined several new prospective zones including: Trumpeter, Ridge and the Main zone extension(Figure 1.2).A total of more than 26 million tonnes of proven and probable massive suiphide ore havebeen discovered in the Buttle Lake camp to date. The H-W deposit is the largest andTABLE 1.1. PROVEN AND PROBABLE GEOLOGICAL RESERVES IN BUTfLE LAKE MINING CAMP,CENTRAL VANCOUVER ISLAND, AS OF 1 JANUARY 1993 (WESTMIN RESOURCES LIMITED, ANNUALREPORT, 1992).Reserves (tonnes) Gold (glt) Silver (g/t) Copper ( %) Lead ( %) Zinc ( %)H-W 8 955 100 2.2 39.6 1.7 0.4 4.3Lynx 315 300 3.0 94.0 1.7 1.1 10.0Price 185 000 1.5 66.4 1.4 1.3 10.4Gap 634400 3.2 151.5 1.8 1.1 13.3Battle 2013700 1.1 24.2 2.6 0.5 12.7Extension 231 100 1.2 60.4 1.7 0.4 3.8Trumpeter 61 200 3.2 68.9 6.3 6.3 4.66 Level 120 500 1.3 91.4 0.4 0.9 6.0TOTAL 12516300 2.1 45.6 1.9 0.5 6.31zFigure 1.1. Location map showing Buttle Lake mining camp within the Paleozoic Sicker Groupof the Wrangellia Terrane. The stratigraphic column of Vancouver Island is simplified fromMuller et at. (1974) and Juras (1987).3MAJOR AREAS OFSICKER GROUPMAJOR TERRANESOF THE CANADIANCORDILLERAkmVANCOUVERISLAND100 km9Figure 1.2 Buttle Lake mining camp, central Vancouver Island, southwestern British Columbia,showing the surface and vertical projections of major orebodies and prospective zones (WestminResources Limited Annual Report, 1992). Note that mine co-ordinates are based on a northwesttrending grid.PLANPROJECTIONMyraValleyH—WMassivesulphidelensDrillholeintersectionMainZoneExtensionTrumpeterZone,PRICEMINETheiwoodCreek(3500N)05001000Mt.MyraSOUTHEASTMainZoneShaftExtensionRidgeBATTLEEastTheiwoodValleyTrumpeterZone(T(‘7contained 16.5 million tonnes of ore (reserves plus tonnage mined to date). It is a giant deposit(between 10 and 50 million tonnes of massive suiphide) according to the size classification ofGibson and Kerr (1992), which is based on Canadian volcanogenic deposits of Archean,Proterozoic, and Phanerozoic age. Compared to tonnages for other deposits hosted in felsic tointermediate rocks worldwide, the H-W deposit is in the upper 20 % (Singer and Mosier, 1984).The Battle zone contains 2 million tonnes of proven and probable reserves (Table 1.1). It islarger than 50 % of volcanogenic deposits worldwide (median = 1.6 Mt; Singer and Mosier,1984) and in Canada (median = 1.4 Mt; Gibson and Kerr, 1992). It is also rich in base andprecious metals. It plots above the 80th percentile for copper, the 90th for zinc, the 80th for goldand the 50th percentile for silver on the grade models of Singer and Mosier (1984). Thecombined Cu+Pb+Zn grade is 15.8 %. Eighty-eight percent of Canadian deposits have combinedgrades of less than 10 % Cu+Pb+Zn, and an expected combined grade of 6% Cu+Pb+Zn (Gibsonand Kerr, 1992).Dimensions of the basin in which massive suiphides of the Buttle Lake camp were depositedare known to be at least 3 by 10 km (Juras, 1987). Only an area 1 by 4 km (Figure 1.2) in sizehas been explored in detail, and the deposit trend is open at both ends. Eight deposits have beenidentified so far (Table 1); some of these may be extensions of other deposits. Othervolcanogenic districts are of similar size with an average diameter of 32 km and with anywherefrom 4 to 20 deposits (Gibson and Kerr, 1992).1.1 HISTORYJames Cross and associates from Victoria staked the claims covering the H-W, Lynx, Priceand Myra mines in 1917 when Strathcona Park was first opened for prospecting. The ParamountMining Co. of Toronto started developing the property, but depressed metal prices andinconclusive findings halted the operations in 1925. The property remained dormant until 1959,when the Reynolds Syndicate acquired the claims. An option to purchase agreement wasnegotiated with Western Mines Limited in 1961. Exploration initially focused on the Lynxshowings. By mid- 1964, 1.5 million tonnes of ore were defined on five levels. To service thenew mine, Western Mines built the present 40-km road along the east side of Buttle Lake.Previous access to the property had been by boat and barge. In 1966 the Lynx pit startedproduction at 775 tonnes per day. Continued drilling established underground reserves and the pitwas phased out in favour of underground production by 1975.Myra deposit was evaluated in 1970. Open-pit production began in 1972 and continueduntil 1986 when the Myra mine closed due to depletion of reserves. In 1976, Brascan Ltd.acquired control of Western Mines Limited and formed Westmin Resources Limited. The Priceshowings were evaluated between 1979 and 1981, but development is on hold.Exploration for new orebodies in 1976 resulted in the discovery of the H-W deposit threeyears later at about 400 m below the Myra valley floor. Production from H-W main lens began in1985. Exploration continued into the 1990’s, and in May of 1991 the high grade Gap lens wasdiscovered. Five months later the Battle zone was found. Current drilling on the property isfocused on definition of the Battle and Gap zones.1.2 SCOPE OF THESISThere are three main goals in this project: (i) to unravel the stratigraphy of the Battle zoneusing detailed logging and petrographic and lithogeochemical techniques, (ii) define the alterationof units associated with the main Battle zone massive sulphide lens, and (iii) to describe andexplain the origin of multiple suiphide horizons within the Battle zone.Twenty-four drill holes on four cross-sections were logged in detail. The cross-sectionsare, from west to east: Section 13+72E, Section 15+85E, Section 16+72E, and Section 17+98E.Section 13+72 has the best preserved geology and many of the type descriptions are based onobservations in this section. Systematic lithogeochemical sampling was carried out on Section15+85E by A. Hamilton and Section 17+98E by the author. Section 16+72E, which was loggedfor geological detail between Section 15+85 and Section 17+98 also has the best cross-section ofan upper zone massive suiphide lens (section 3.2.2.6). Drill hole 14-720 (Section 14+02) fromthe Gap zone was logged and sampled for additional detail on the quartz porphyritic rhyolite(section 3.2.2.7).Whole rock analyses were done on 150 altered and unaltered samples to determine bothoriginal and alteration lithogeochemistry. Thin sections of whole rock samples were cut toidentifr minerals and verify alteration patterns observed in the geochemical data. Microprobeanalyses of sericite and chlorite complement the lithogeochemistry.Polished thin sections of 150 massive suiphide samples were cut for petrographic analysis ofthe ores. Textural analysis of the main ore types and identification of all mineral species formed amajor component of this study. Microprobe analyses complement the petrography. Statisticalmethods were used to characterize variations in the assays of lenses of similar mineralogy.CHAPTER 2REGIONAL AND MINE GEOLOGY2.1 REGIONAL GEOLOGYMassive sulphide deposits of the Buttle Lake mining camp occur within the Myra formationof the Paleozoic Sicker Group. The Sicker Group is the oldest stratigraphic unit recognized onVancouver Island, and represents the base ofWrangellia, an allochthonous terrane that underliesmost of the Island (Jones et a!., 1977). The Sicker Group in exposed by three major fault-bounded uplifts: Buttle Lake, Cowichan - Home Lake and Nanoose (Figure 1.1). The ButtleLake camp occurs in the Buttle Lake uplift.An informal revised stratigraphy for the Buttle Lake uplift is in Table 2.1. This table offormations, established by Juras (1987), incorporates earlier work by Yole (1969), Jeffery (1970)and Muller (1980). In order of decreasing age the formations recognized are: Price, Myra,Thelwood, Flower Ridge, Buttle Lake and Henshaw.Price formation consists of feldspar-pyroxene-porphyritic basaltic andesite flows, flowbreccias, hyaloclastites, pillowed flows and minor volcaniclastic sediments. Most flows contain 1to 8 % quartz and chlorite filled ovoid amygdules less than 1 mm long. The freshest rocks aremoderately altered to chlorite-epidote-plagioclase-actinolite assemblages. Rocks below massivesulphide lenses are totally altered to sericite and pyrite with or without chlorite. Price formation isover 300 m thick as indicated by diamond drilling; the base is not exposed. It is Late Devonian orolder based on an isotopic Late Devonian age (Table 2.1) for the overlying Myra formation. Thebasaltic andesite probably represents a major period of early arc volcanism (Juras, 1987).Myrafonnation is 310 to 440 m thick and is composed of rhyolitic to basaltic rocks withlesser sedimentary units. Most volcanic rocks are elastic, with lesser flows and intrusions.Sedimentary rocks are primarily volcanic greywacke with interbedded argillite and chert.Lithologic units are continuous along the northwest trend of the ore zones (Figure 1.2), but haveabrupt lateral northeast to southwest facies changes. Deposition of the Myra formation wascomplex, because material apparently was deposited &om three separate volcanic centres (Juras,1987). Rhyolite flows and volcaniclastic rocks were formed within an ancient volcanic arc to thenortheast, towards Buttle Lake. Massive sulphides, pelagic deposits, volcanogenic sediments andandesite flows fill an intra-arc basin. Mafic flows and volcaniclastic deposits mark an intra-arc orback-arc provenance to the northwest, towards Mount Myra. Uranium-lead zircon dating ofrhyolite by Juras (1987) established a Late Devonian age of 370 Ma for the Myra formation.Details of the formation are outlined in the section on mine geology.TABLE 2.1. TABLE OF FORMATIONS FOR THE PALEOZOIC SICKER GROUP IN THE BUTI1E LAKEUPLIFT, CENTRAL VANCOUVER ISLAND, SOUTHWESTERN BRITISH COLUMBIA (MODIFIED FROMJURAS, 1987).Age Formation Thickness LithologyEarly Permian (?) to Henshaw 5-100 m Conglomerate, epiclastic deposits and pumiceousEarly Triassic formation tuffEarly Permian to Buttle Lake 300 m Crinoidal limestone and minor chertPennsylvanian’ formationMississippian to Early Flower Ridge 650+ m Moderately to strongly amygdaloidal mafic lapilliPermian’ formation tuff(seoria clast), tuffbreccia, minor tuff andflows, and syndepositional(?) sills2Early Mississippian (7) Theiwood 270-500 m Subaqueous pyroclastic deposits, siliceousformation tuffaceous sediments and mafic sillsLate Devonian3 Myra formation 310-440 m Intermediate to felsic volcanics, volcaniclastics,minor sediments and massive sulphidemineralizationLate Devonian or older Price formation 300+ m Feldspar-pyroxene porphyritic basaltic andesiteflows, flow breccias and minor sediments1. Pennsylvanian to Early Permman based on brachiopods (Fyles, 1955), fusulinids (Sada and Danner, 1974), foraminifera(Muller eta!., 1974) and conodants (Brandon et a!., 1986).2. 276 ± 8 Ma, K-Ar hornblende: Early Permman (unpublished data: C. Godwin, J. Harakal and D. Runkle, The University ofBritish Columbia).3. 370 ± 6 Ma, U-Pb zircon (Juras 1987).Theiwoodformation unconformably overlies the Myra formation. It is 270 to 500 m thickand consists of fine grained siliceous tuffaceous sediments, volcaniclastic debris flows andpenecontemporaneous mafic sills. Tuffaceous sedimentary units are 5 to 30 m thick.They are generally massive fine to coarse crystal-lithic tuff at the base and are capped by palegreen to grey, locally cherty, thin-bedded tuffaceous mudstone and siltstone. Most units representan A, E turbidite sequence. Volcaniclastic debris flows are 4 to 25 m thick, moderately wellsorted, crudely stratified, and consist of pumiceous-lithic, fine lapilli tuff and coarse tuff. Scoured14bases and boulder sized rip-up clasts of tuffaceous sediment units are common. Mafic sills are 1to 90 m thick and consist of basaltic andesite. Contacts with the sediments are locally peperitic,indicating that the Thelwood formation was unlithified at the time of sill intrusion (Juras, 1987).The Thelwood formation has not been dated in the Buttle Lake uplift. However, the possiblycorrelative sediment-sill unit of Muller eta!. (1974) in the Cowichan - Home Lake uplift containsradiolaria ofMississippian age (Muller, 1980).Flower Ridgeformation is dominantly basaltic volcaniclastic rocks in conformable contactwith the Theiwood formation. It is over 650 m thick and is characterized by stronglyamygdaloidal feldspar and pyroxene porphyritic basaltic lapilli-tuff and pyroclastic breccia.Amygdules are filled with quartz, albite, clinozoisite and/or epidote and pumpellyite. Other rockunits include tuffaceous siltstone and wacke, basalt flows and flow breccias, bedded tuffaceousmudstone and argillaceous sediments. The section is expanded by a large number of hornblendephyric basaltic sills. A K-Ar date of 276±8 Ma on hornblende (unpublished data: C. Godwin, 3.Harakal and D. Runlde, 1991) from the sills indicates that this unit may be Early Permian if thesills are penecontemporaneous. The Flower Ridge formation marks the resumption of shallowmarine mafic volcanism.Buttle Lakeformation is primarily massive to bedded crinoidal limestone with associatedchert lenses and nodules, greywacke and argillite. This unit is 100 to 500 m thick andconformably overlies the Flower Ridge formation. The age of this unit is Pennsylvanian to EarlyPermian based on brachiopods (Fyles, 1955), fusulinids (Sada and Danner, 1974), foraminifera(Muller eta!., 1974) and conodants (Brandon eta!., 1986).Henshawformation both overlies and locally scours out the Buttle Lake formation. It is 5to 100 m thick and is composed of conglomerate, distinctive purple epiclastic deposits and purpleto grey pumiceous tuff beds. Local crinoidal limestone boulders are characteristic. The Henshawformation marks the unconformity between the Buttle Lake limestone and basalt of the overlyingEarly Triassic Karmutsen Group. It is therefore Early Permian (?) to Early Triassic in age.[22.2 MINE GEOLOGY: THE MYRA FORMATIONThe Myra formation is a complex sequence of mafic to rhyolitic volcaniclastic rocks andlesser flow units that fill a basin that trends northwest. Massive sulphides occur mainly at twostratigraphic levels within the Myra formation. The lowest member of the formation, H-Whorizon, overlies the Price formation andesite and hosts the H-W main lens, Battle and Gap zones.The upper Lynx-Myra-Price horizon hosts several small sulphide lenses. The formation ischaracterized by relatively continuous units that trend northwesterly but have rapid northeasterly-southwesterly facies variations (Walker, 1985).Juras (1987) recognized ten lithostratigraphic units in the Myra formation, displayed on theschematic cross-section of Figure 2.1. They are, from bottom up: (i) H-W horizon, (ii)hangingwall andesite, (iii) ore clast breccia, (iv) lower mixed volcaniclastic rocks, (v) upperdacite/5E andesite, (vi) Lynx-Myra-Price horizon, (vii) G-flow, (viii) upper mixed volcaniclastics,(ix) upper rhyolite, and (x) upper mafic unit. The use of the term ‘horizon’ to describe the ore-bearing or ore-equivalent lithologic units comes from Sangster (1972) and is imbedded in the mineterminology and available literature on the Buttle Lake deposits. For this reason the terms ‘H-Whorizon’ and ‘Lynx-Myra-Price horizon’ are retained in this paper, although the word ‘horizon’usually refers to a distinctive very thin bed (Bates and Jackson, 1987). Descriptions of theselithologic units (below) are mostly from Juras (1987). Price formation, footwall to the largemassive sulphide lenses in H-W horizon, is discussed in detail in Chapters 35 and 6.2.2.1 LithologyH-Whorizon is composed mainly of felsic flows and volcaniclastics (Walker, 1985). It is 15to 200 m thick and occurs throughout the mine area. There are five general members within H-Whorizon: (i) massive sulphide lenses, (ii) argillite, (iii) H-W mafic unit, (iv) pyroclastic andepiclastic deposits, and (v) felsic flows and domes (Juras, 1987; Juras and Pearson 1990), H-Whorizon is discussed in detail in the section on the geology of the Battle zone (Chapter 3).13Massive suiphides occur in pyrite rich, zoned lenses with chalcopyrite rich basal and corezones and zinc rich margins. The H-W main lens is the largest on the property, and contained atotal of 12 million tonnes of massive sulphide (Table 1.1). Other lenses in this stratigraphicposition include H-W north lenses and the Battle zone. The argillite member is 1.5 to 45 m thickand consists of black siliceous argillite, fine to coarse rhyolitic tuff and minor chert. It is massiveto thin bedded, and represents A, E and A, B, E Bouma turbidite sequences. The H-W mafic unitintruded and covered the argillite member. It is a pale green pyroxene-phyric basalt withpeperitic, pillowed and quench brecciated (hyaloclastite) margins. Pyroclastic and epiclasticdeposits make up most of the H-W horizon in the central region. Pyroclastic deposits aredominated by quartz-feldspar crystal-lithic and pumiceous lapilli tuff, and coarse to fine tuff.Epiclastic deposits consist of debris flows, some of which contain up to 25 % fragments ofPriceformation andesite. Felsic flows and domes are of three types: quartz-feldspar porphyriticrhyolite, aphyric to feldspar porphyritic rhyolite, and feldspar porphyritic dacite (Juras, 1987).Hangingwall andesite is mostly basaltic andesite flows and flow breccias. The unit is up to100 m thick; individual flow members may be over 3 m thick. Monomict hyaloclastite brecciadominates the package. Less than 5 % ofbreccia fragments are rhyolite, dacite or suiphide. Mostbreccias consist of in situ hyaloclastite, with lesser resedimented hyaloclastite. Well sortedgreywackes are also present. The hangingwall andesite is thickest over the H-W main lens,probably because that lens was deposited in a topographic low (Pearson, 1993). This unit isdiscussed in detail in Chapter 4.Ore-clast breccia is characterized by massive suiphide clasts and olistoliths of pyritemineralized rhyolite up to 50 m long by 15 m wide (Juras, 1987; Juras and Pearson, 1990). Theunit is up to 90 m thick and consists of a series of submarine debris flows and lesser pyroclasticdeposits. There are three distinct members within the ore-clast breccia (Juras, 1987): (i) rhyoliterich volcaniclastic breccia, (ii) rhyolite-poor volcaniclastic breccia, and (iii) interzone pyroclasticrhyolite. Clast types within the volcaniclastic breccia members are highly variable. In decreasingji4order of abundance they are: feldspar-phyric andesite, amygdaloidal mafic, dacite, quartzfeldspar-porphyritic rhyolite, massive suiphide, fine rhyolite tuff, chert and argillite. Clastdiameters range from 1 cm to 150 cm. The interzone rhyolite member is up to 20 m thick andconsists of bedded felsic tuff, lapilli tuff and tuff-breccia. It represents a period of felsicphreatomagmatic activity (Juras, 1987) that interrupts slide and debris flow sedimentation.Lower mixed volcaniclastic rocks are dominated by andesite with lesser dacite fragments.The unit also includes rare thin flows of andesite. The unit is up to 90 m thick and containsbedded clastic sequences and coarse elastic deposits. Bedded elastic sequences contain mostlyaphyric to plagioclase-phyric subrounded andesite fragments with lesser broken to euhedralplagioclase crystals. Coarse deposits contain two types of andesite and lesser dacite clasts. Mostandesite fragments contain 15 % feldspar crystals and have perlitic textures. Other andesitefragments are feldspar glomeroporphyritic. Lower mixed volcaniclastics are distinguished fromthe ore-clast breccia by the absence of rhyolite and massive sulphide fragments (Juras, 1987).Upper dacite/5E andesite occurs at the southeast and northwest ends of the mine property,respectively. The upper dacite is divided into an upper and a lower member. The lower member,up to 60 m thick, contains resedimented hyaloclastite, pillow breccia and subaqueous pyroclasticdeposits. The upper member is mostly intermediate flows with yellow-green, dark grey andpurple feldspar porphyritic flow clasts. The flows are medium to dark green with 25 % feldsparcrystals. The 5E andesite sequence of massive to pillowed basaltic andesite flows and flowbreccias is up to 250 m thick. The upper dacite and the SE andesite represent twocontemporaneous, but distinct, eruptive events (Juras, 1987).Lynx-Myra-Price horizon is massive to bedded, fine to coarse tuff, quartz-feldspar crystaland pumiceous rhyolite lapilli tufT, and lesser chert (Juras, 1987). Massive suiphides occur at twolevels within the Lynx-Myra-Price horizon. Some lenses are located at the base of the horizonwhere they are underlain by schistose sericite-quartz-pyrite feeder zones within the SE andesite.Other lenses occur at the upper contact with G-flow. Upper suiphide lenses have no underlyingIsFigure 2.1 Schematic cross-section of the Myra Formation, Buttle Lake mining camp, centralVancouver Island, southwestern British Columbia. The Myra Formation hosts all knownvolcanogenic massive suiphide deposits within the camp. Figure is compiled from Juras (1987)and Pearson (1993).VV\ApproximateScaleThelwoodformationNorthfaultLEGENDHanglngwallandesiteH—WHORIZONUpperrhyoliteUppermixedvolcaniclastiosUppermafico0 0G—flowLynx—Myra—PricehorizonUpperdacite/5EandesiteAALowermixedvolcaniclasticsPOre—clastbrecciaAAAAA,AAAAAA,‘SAAAAAAAAAAAAAAAS‘SAAAAAAAAAd.—AAAAAAAAAAAA•TAAAAAA6AAAAAAA’,..,,AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAALAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA4Quartzfeldsparporphyry(EfI)RhyoliteMassivesuiphidePyritestringersPriceandesiteUnconformity/...4Priceformation0100200300mVH-WlensH—Wmainlens(Battlezone1000mnorthwest)SOUTHWESTNORTHEAST1-1feeder zones. The variably altered rhyolite tuffs and lapilli tuffs probably served as a conduit formineralizing fluids, which were channeled laterally to hydrothermal discharge sites. Massivesulphide lenses are composed of banded sphalerite, barite, pyrite, chalcopyrite, galena andtennantite.G-flow is a widespread but thin, 2 to 15 metre thick, package of komatiitic basalt flows andhyaloclastite breccias that occur immediately above the Lynx-Myra-Price horizon (Juras, 1987;Juras and Pearson, 1990). Least altered flow rocks consist of 5 % augite glomerocrysts, tracechromite microphenocrysts and trace olivine phenocrysts. The groundmass is fine grainedactinolite, chlorite, plagioclase and relict clinopyroxene. Hyaloclastite breccias are locallyhematite altered to a distinctive purple. Jasper locally fills interstices between breccia fragments.Upper mixed volcaniclastics are mafic to intermediate fine to coarse deposits up to 50 mthick (Juras, 1987; Juras and Pearson, 1990). Fine deposits are thin to medium bedded, wellsorted, normally graded feldspar-crystal tuff of intermediate to mafic composition. Locally, thesedeposits are capped by maroon fine tuff. Coarse deposits are characterized by a wide texturalvariety of mafic to intermediate clasts in a matrix composed of 5 to 15 % feldspar crystals in anepidote-albite-chlorite groundmass. Lesser clast types include massive to flow-banded rhyolite,rip-up clasts of tuffaceous siltstone and white to black chert.Upper rhyolite is 50 to 65 m thick and contains two members: (i) a pyroclastic richmember and (ii) a siliceous argillite and chert dominant member (Juras, 1987; Juras and Pearson,1990). The pyroclastic member is up to 50 m thick and generally coarsens upward; individualbeds are normally graded. The deposits are thin to medium bedded crystal-lithic and pumiceouslapilli tuff, and lesser fine tuff, coarse tuff and tuff-breccia. The siliceous argillite and chertmember, 1 to 15 m thick, consists of grey to black siliceous argillite, white to pale green chert,green to grey fine rhyolite tuff and minor jasper. Round radiolarian “ghosts” occur in theargillaceous material.isUpper maJlc unit is pyroxene-feldspar porphyritic basalt. It is 5 m to over 200 m thick andis the uppermost unit within the Myra formation (Juras, 1987; Juras and Pearson, 1990). Becausethe Myra formation is unconformably overlain by the Theiwood formation, the upper mafic unit isabsent in some areas. Most of the unit consists of pyroclastic and hydroclastic deposits. Flows,present in the middle to upper parts of the upper mafic unit, are 3 to 15 m thick.2.2.2 StructureThe main structural feature of the Buttle Lake camp is a subhorizontal, northwest trendingasymmetric anticline with a steeply dipping southwestern limb and a gently dipping northeast limb(Walker, 1985, and Figure 2.1). Related minor fold structures are most common in massivesuiphides and associated sericitic alteration zones. Axial planar foliation trends northwest withnearly vertical to steeply northeast dipping surfaces. Most fragmental rocks have stretched claststhat reach length to width ratios of greater than 10:1 (Walker, 1985). In general, the long axes ofstretched clasts parallel the hinge of the anticline. Prominent joints, perpendicular to the foldaxis, are locally quartz-carbonate veined and are present throughout the mine area.Faults of various ages and orientations cut the mine stratigraphy. Most are high-anglenormal faults with trends to the northeast, north, northwest and east-southeast; some are strike-slip (Juras, 1987). Figure 2.1 shows the North fault which dips around 450 and down drops thenortheastern part of the mine stratigraphy by about 800 m. It is one of the youngest faults as itcuts the overlying Theiwood formation. Some of the normal faults are restricted to the Priceandesite and interpreted to be synvolcanic; these commonly form feeder zones to massive sulphidemineralization. Some of these faults were reactivated and have postmineral reverse or normaldisplacements.2.2.3 MetamorphismDescriptions of the deformational history and metamorphic events in the Buttle Lake upliftare in Juras and Pearson (1990), Juras (1987), Walker (1985) and Muller (1980). The mainiqdeformational event is Mesozoic folding that resulted in northwest trending, horizontal toshallowly northwest plunging, upright open folds in the Thelwood formation (Juras, 1987). Atighter style of folding in the underlying Myra formation may reflect the different rheology of thetwo formations, or a pre-Theiwood folding event. Following Mesozoic deformation, intrusion ofthe Jurassic Island Intrusions (Figure 1.1) caused local rotation of bedding. Cretaceous andTertiary tectonics related to uplift of the Buttle Lake area might be represented by north-northeastand east-northeast trending joint sets observed in the mine area (Juras, 1987).Metamorphism of rock units in the Price and Myra formations began during deposition as aresult of regional submarine hydrothermal metamorphism. Metamorphic assemblages are highlyvariable as they reflect the wide diversity of rock types within the Price and Myra formations.Juras (1987) documented the metamorphic mineral assemblages for the different rock units andconcluded that: (i) submarine hydrothermal metamorphism had the most important effectregionally on the rocks and (ii) effects of later burial metamorphism or dynamothermalmetamorphism include coarser, recrystallized phyllosilicate phases and local development ofpressure shadows.20ChAPTER 3GEOLOGY OF THE BATELE ZONE3.1 iNTRODUCTIONMassive sulphide lenses occur at two stratigraphic levels within the H-W horizon: (i) at thePrice formation contact (Battle [and possibly the Gap] massive suiphide lenses), and (ii) at thecontact between rhyolite volcaniclastics and overlying rhyolite flows (upper zone massive sulphidelenses). The Gap zone is about 100 m above the Battle zone; this either reflects thepaleotopography of the Price andesite during massive sulphide deposition or post mineraldisplacement. Geology of the Battle and Gap zones is complicated by synmineral and postmineralfaulting, rapid facies changes, significant paleotopography and texturally destructive alteration.To better understand the depositional environment a detailed stratigraphy of the H-W horizon wasestablished in the Battle zone (Figure 3.1). Gap zone stratigraphy is also presented in Figure 3.1,but is preliminary because only two drill holes (14-757; Section 13+72E and 14-720; Section14+02 E) were logged through the zone. An interpretation of the stratigraphy and areconstruction of the depositional environment is in section 3.3.Twenty four drill holes on three cross-sections through the Battle zone were logged andsampled in detail. The cross-sections are, from west to east: 1 3+72E, 1 5+85E and 1 7+98E.Section 13+72E (Figure 3.2) has the best preserved geology and many of the lithologicdescriptions are based on observations in this section. This is also the only section where the mainBattle massive sulphide lens has not been significantly disrupted by postmineral faulting. Section15+85E (Figure 3.3) is the most representative geologic section of the Battle zone, and shows allthe lithologic units, particularly those within the rhyolite flow-dome complex. Section 17+98E(Figure 3.4) illustrates the geometry of the south trough, a thick accumulation of massive sulphidewithin the eastern third of the Battle zone.2’3.2 LITHOLOGY3.2.1 Price FormationPrice formation is a sequence of massive to pillowed basaltic andesite flows, volcanicbreccias, inter-flow elastic sediments and turbidites. It is over 300 m thick, and is the lowermostunit in the mine area and the Buttle Lake uplift (Juras, 1987). The base has not been identified.Only the upper 75 m ofthe formation have been intersected in Battle zone exploration drilling.All of the drill hole intersections are intensely altered; primary textures are only sporadicallypreserved.Two types of andesite flows throughout the Buttle Lake mining camp were defined by Juras(1987) based on phenocryst assemblages. They are: (i) pyroxene-feldspar phyric flows with 5 %euhedral clinopyroxene crystals 1 to 10 mm long and 3 % plagioclase crystals 0.8 to 2.5 mm long,and (ii) feldspar-phyric flows with 15 % plagioclase crystals 0.6 to 5 mm long and trace to 0.5 %clinopyroxene phenocrysts 0.5 to 2.5 mm across. Feldspar-phyric rocks are prevalent in theBattle zone (Plate 3.1 a).Feldspar-phyric flows contain feldspar both as glomerocrysts and as individual crystals inthe matrix. Most feldspar is altered to sericite, carbonate and iron rich clinozoisite. Traces ofchlorite altered pyroxene crystals are also present. One to 7 % quartz and chlorite filledamygdules 0.3 to 1 mm across are characteristic of the Price andesite (Plates 4.1 a and ai); theylocally reach diameters of 8 mm. In general, quartz rims the inside of the amygdule, andmagnesian chlorite fills the center. In areas of moderate hydrothermal alteration, the amygdulesare still distinguishable by their shape, although the quartz is recrystallized to a coarse grainedaggregate and the chlorite is removed or altered to sericite.Contacts to individual flow units may be massive, devitrified glass or quench brecciated(hyaloclastite; Plate 3.1 a). Devitrifled tachylite is dark green or black, and altered to sericite andchlorite. Hyaloclastite mostly occurs as unsorted deposits up to 6 m thick on the top of massiveflows. It consists of individual fragments of andesite up to 30 cm across in a finely shatteredmatrix of devitrifled tachylite fragments. In some areas of the H-W mine, hyaloclastite is scouredand incorporated with overlying felsic mass-flow sedimentary units (Allen, 1993). Pillow brecciais also common. Pillow fragments are pinkish, scoriaceous and have convex edges. Inter-flowsediments consist of grey to green greywacke. They are moderately well sorted to well sortedand fine upwards; some of them are turbidites.3.2.2 H-W HorizonH-W horizon consists of the following seven members in the Battle zone from bottom up:(i) Battle (and possibly Gap) zone massive suiphide lenses, (ii) fine rhyolitic tuffaceous deposits,(iii) H.-W mafic sills, (iv) coarse rhyolite pyroclastic deposits, (v) rhyolite tuffaceous sediments,(vi) upper zone massive suiphides, and (vii) rhyolite flow-dome complex. These members aredetailed below.3.2.2.1 Battle and Gap zone massive suiphide lensesMassive suiphide lenses in the Battle zone occur at the contact between the basaltic andesiteof the Price formation and the dominantly felsic volcanic units of H-W horizon. The largest lens,the main Battle massive sulphide lens, ranges from 130 to 210 m wide and 4 to 25 m thick. It hasa minimum strike length of 500 m, and is open at both ends. It is bounded to the north by anormal fault. Other, smaller lenses have been identified towards the eastern third of the Battlezone by definition drilling.The main Battle massive sulphide lens is mineralogically zoned from: (i) footwall sericitequartz-pyrite stockwork mineralization that is in the Price andesite through, (ii) chalcopyrite richmassive sulphide (Plate 3 .2a), (iii) banded massive sulphide mineralization in the central region(Plate 3.2b), (iv) pale yellow massive sphalerite at the top and periphery (Plate 3.2c), and (v)laminated or bedded massive sulphides locally preserved at the top of the yellow sphalerite zone(Plate 3.2d).Z3Figure 3.1. Stratigraphic columns of H-W horizon as established in the Battle and Gap zones.Gap zone stratigraphy is preliminary as only two holes were logged through the zone. Scale onthe left is in m.Bctttle ZoneIvvvvvvvvvvvvvvvvvvvv Gctp ZoneIvvvvvvvvvvvvvvvvvvvvRRRlz(oiitcflow—domecompleaUpper sammassivesuiphidelensesRhyoleeiufjoceoussedimentsrloojolCe \pyroalasticdepositsFwIIIIIOZitICtt#s000UO+ + ++ + ++ + +÷ + +• + ++ +• + ++ +RhojolUeflow-domeC—++ + ++ +÷ + ++ ++ + ++ ÷+ + ++ ++ + ++ +In situ and resedimentedhyaloclastite brecck,Mdesite flowGreen quartz—feldspar—porphyritic rhyoliteQuartz—feldspar—porphyritic rhyoliteFeldspar—quartz—hornblende rhyoliteporphyry dikeLaminar flow—bandingBottom—flow brecciaTennantite—rich massivesulphideRhyolite tuffaceoussediments with localbeds of accretionaiy(?)lapilliRhyolite tuft withpumice blacksPumiceous lapilli tuffLaminated, chertyrhyolite fine Luff (FRTD)PeperiteIn situ hyaloclastitebrecciaThin—bedded massivesulphideYellow sphalerite—richBanded black sphaleriteand chalcopyrite+pyriteCholcopyrite—richMassive to pillowedflows and flowbrecciaRh5olitetooffaceooossedimentsmasnovesulpMdelemoIIIIn situ and resedimentedhyaloclastite brecciaAndesite flowGreen quartz—feldsparporphyritic rhyoliteBaritic massive sulphidePyritic massive sulphideQuartz porphyriticrhyolite sillMassive to pillowedflows and flowbrecciaH-WmaltsF1IT15MainBattlemassiveo,4phi4elensC’”00)vvv,vvvvvv,vvvvvv,vvvvvv,‘N÷ •i+vvvvvv,vvvvvv’vvvvvv,vvvvvv,vvvvvv,vvvV V V VV V v viVvvV1V V V VVVVV,V V V VIVVVV’l—zsFigure 3.2 Cross-section of the Battle zone, 1 3+72E, Buttle Lake mining camp, centralVancouver Island, southwestern British Columbia. Mine co-ordinates are used, but the view is tothe northwest.14100N14200N4300N3100EL Section13+72E3000ELSCALE025 HangingwallandesiteFeldspar—quartz—hornblenderhyoliteporphyrydikeQuartz—feldsparporphyriticrhyohteRhyolitetuffaceoussediments3100ELupperBattLezone / 14—7562900EL(367ni)14-754\,357m/751/Coarserhyolitepyr1asticdeposits14—750rhyolitetuffwitpumiceblockshyaloclastite(366xn)(384m)PriceandesiteMassivesuiphidepumiceouslapillituff2900ELpillowbrecciaerb(.bpeperiteFinerhyoliUctuffaceousdepositschertandfinerhyolitetuftthin—beddedbrowntogreysiltstoneQuartzporphyriticrhyoliteH—Wmaficsillfault,certainfault,uncertaingeologicalcontact,certaingeologicalcontact,uncertainL5Figure 3.3 Cross-section of the Battle zone, 1 5+85E, Buttle Lake mining camp, centralVancouver Island, southwestern British Columbia. Mine co-ordinates are used, but the view is tothe northwest.14100N14200NPrice(?)andesite+QP;—-++++\+++.t,,‘++\++++++\++++__++++.+÷÷÷-‘—++HangingwallandesiteGreenquartz—feldsparporphyriticrhyoliteQuartz—feldsparporphyriucrhyoliteRhyolitetuffaceoussedimentsPumiceouslapillituff14—906(329m)Finerhyolitictuffaceousdepositschertandfinerhyolitetuff3100ELSection15+85ESCALE02550m0EL.3100ELGQFP—QFP*+**+++++**+•4+++++++++++tr++.++++++++++++++++1+++++++++++++++++++++4++++\+++++++++V++++++1+++++++++++••++•**ij+++++.4**.4+4.4+.‘.!•++4t+1-.4+44’+++*++.‘:44•4.*+++.4++++‘-+*+**+•+4.4.+*+..4+++1*++4.++V++++.4++11.4++4\+++++.•...++++.4++.4+++‘.4++.4+++4.4++.4++4.4,4++.4+++4*+14++÷+4\++.4++1•4+4\fr•++*.4+.4.4.4.4+÷l++•1•*.4+++.++4+++.4++.44+++j++•+4.+++V:.,vvvvvvv’14—912’*y:c(311m) 14—9W”(335m)Battlezone14—908(305m)2900EL14—907””””(299m)14—900(302m)14—904(319m)“Vi (339m)/thin—beddedbrowntogrey‘‘siltatoneQuartzporphyriticrhyoliteH—WmaficsifiPriceandesiteMassivesuiphide2900EL‘hyaloclastitefault,certainfault,uncertaingeologicalcontact,certain—geologicalcontact,uncertain29Figure 3.4 Cross-section of the Battle zone, 17+98E, Buttle Lake mining camp, centralVancouver Island, southwestern British Columbia. Mine co-ordinates are used, but the view is tothe northwest.141N14200N4300NHangingwallandesiteGreenquartz—feldsparporphyriticrhyoliteFlow—bandedquartz—feldsparporphyriticrhyoliteRhyolitetuffaceoussedimentsCoarserhyolitepyroclasticdepositsrhyolitetuffwithpumiceblockspumiceouslapihituftSection17+98E3100ELSCALE—02550m3000F+ +4÷ + +14—917(351m)14—-(342m)14—920(311m)14—914(304m)3100EL3000EL2900EL14—915(303in)14—919(332m)2900EL•t’peperiteFinerhyolitictuffaceousdeposits‘hyaloclastitechertandfinerhyolitetuffopillowbrecciathin—beddedbrowntogrey‘i’siltstoneVitricquartz—porphyriticrhyolitefault,certainH—Wmaficsilt-.-.-.-.-.-fault,uncertainPriceandesitegeologicalcontact,certain•Massivesuiphidegeologicalcontact,uncertain(AJ3’The Gap massive sulphide lens is a polymetallic orebody about 20 to 30 m high, 40 to 50 mwide and about 250 m along strike (Pearson, 1993). It is located about 200 m northeast (relativeto true north) and about 100 m above the main Battle massive sulphide lens. Footwall lithologyof the Gap massive sulphide lens is poorly constrained because of proximity to a major strike-slipstructure. Initial observations indicate that the immediate footwall is andesite, possibly part of thePrice formation (Figure 3.1 and Figure 3.2; Section 13+72E). The change in elevation isinterpreted to be due to the paleotopography of the andesite (Section 4.3; Figure 3.5), but couldalso be due to post mineral displacement along faults. The Gap massive sulphide lens is zonedfrom: (i) footwall sericite-quartz-pyrite stockwork mineralization that is in the Price andesite, andto a lesser extent, quartz porphyritic rhyolite, through (ii) lower pyritic massive sulphide, and (iii)upper and peripheral baritic massive suiphide. Pyritic massive suiphides contain pyrite, sphalerite,chalcopyrite, bornite, tennantite and anilite (Plate 3.3a). Baritic massive sulphide from the upperpart of the Gap lens contains sphalerite, barite, pyrite, quartz, galena, chalcopyrite and tennantite(Plate 3 .3b). Barite is locally mammilary; convex surfaces face up-stratigraphy.3.2.2.2 Fine rhyolitic tuffaceous depositsFine rhyolitic tuffaceous deposits are mostly tuffaceous chert or thinly bedded fine tuff. Atypical sequence overlying the ore zone consists of: (i) fine rhyolite tuff with compacted,devitrified, sericitized, pumice fragments, (ii) massive grey, purple or green tuffaceous chert (Plate3.4a), and (iii) thinly to medium-bedded, normally graded, well sorted, variably silicified rhyolitecherty tuff (Plate 3 .4b). All members of this sequence are not present everywhere. In some areasto the west, fine rhyolitic tuffaceous deposits are underlain by brown to grey, thin-beddedmudstone and shaly sandstone (Figure 3.2; Section 13+72E). These deposits are not widespreadenough to describe as a separate unit.Massive grey, purple or green tuffaceous chert forms a distinctive marker (Figure 3.3;Section 15+8 SE). It occurs within 5 m above the massive sulphide lenses. It attains thicknessesofup to S m and has a conchoidal fracture. Pure chert is rare; usually it contains a tuffaceouscomponent and a minor sulphide component. The tuffaceous component commonly comprisesabout 1% broken quartz crystals and 8% fine grained sericite. Abundant sericite usually tints thechert pale green. The quartz crystals have ragged rims that are intergrown with a fine grainedquartz matrix. Feldspar grains are notably absent or altered beyond recognition. The sulphidecomponent is usually pyrite, with rare sphalerite. Suiphides may occur as thin beds or laminaethat form up to 2 % of the rock, but suiphide stringers are more common, especially above themassive suiphide lens. These stringers usually consist of chalcopyrite, sphalerite and pyrite. Greychert contains pyrite finely disseminated throughout the matrix.3.2.2.3 H-W mafic sillsH-W mafic sills from 5 to 30 m thick cross-cut lower strata within H-W horizon (Figure4.2; Section 13+72E). They are pinkish-brown due to pervasive sericite-pyrite-quartz alterationassociated with the ore forming hydrothermal system (Plate 3. 5a). Unaltered examples of this unitwere not observed in the Battle zone. Both upper and lower contacts of the sills are chaotic, withswirls of white material incorporated into the mafic rock (Plate 3 .5b). The white material issiliceous, contains a trace of quartz crystals, and is most likely silicified felsic sediment that hasbeen incorporated from the fine rhyolite tuffaceous deposits. The brown material is devitrifiedglass, probably sideromelane or palagonite. The chaotic boundary is peperite, which impliesintrusion into unconsolidated felsic sediment. Peperitic margins change laterally to pillow breccia(Figure 3.2). Hyaloclastite occurs at the base of most sills (Figure 3.1). Fragments in thehyaloclastite are arcuate, generally less than 5 cm across, and occur in a finely shattered matrix.They retain in situ breccia textures, therefore they are not resedimented. H-W mafic locallyintrudes into the top of the main Battle zone massive sulphide lens, and consequently, containssulphide fragments (Juras, 1987).3.2.2.4 Coarse rhyolite pyroclastic deposits33Coarse rhyolite pyroclastic deposits are composed of two related members that form adistinct marker horizon: (i) pumiceous lapilli tuff, and (ii) rhyolite tuff with pumice blocks (Figure3.2; Section 1 3+72E). Pumiceous lapilli tuff is about 3 m thick, but locally reaches thicknessesgreater than 10 m. It contains about 15% cognate lithic fragments of quartz porphyritic (QP)rhyolite (section 3.2.2.7), 10 % whole and broken quartz crystals 1 to 10 mm across (Plate 3 .6a),and 5 % accidental lithic clasts of sulphide, chert, mafic volcanic rock and pale green mudstonesupported in a matrix of compacted, sericitized pumice fragments. The pumiceous component isdark grey-green to black, and altered to sericite. It has a eutaxitic texture that appears to reflectwelding (Juras, 1987; figures B2 to B4). Baked mudstone fragments and pyrrhotite alteredsuiphide fragments observed by Juras (1987) in less altered equivalents of this unit above the H-Wmine further support the welding hypothesis. Quartz porphyritic fragments (Plate 3.6ai) areangular to subangular, normally graded, and fine from over 5 cm across at the base of the unit to0.5 cm across at the top. Characteristic quartz phenocrysts distinguish these lithic fragments fromoccasional accidental chert fragments (section 3.2.2.3) or mudstone fragments. Rare, darkbrown, intensely sericitized fragments may be derived from the H-W mafic sills (?).Rhyolite tuff with pumice blocks forms deposits between 20 cm and 2 m thick on top of thepumiceous lapilli tuff, particularly in the western part of the Battle zone (Figure 3.2, Section13+72E). This unit is characterized by conspicuously large fragments of black, sericitized,flattened, crystal rich pumice (Plate 3.6b) up to 30 cm across. These blocks are supported in awell sorted, laminated matrix of coarse to fine tuff. Thin beds of white, cherty material about 10cm thick separate individual sub-units. These beds are probably silicified ash-siltstone suspensionsediment layers (Allen, 1993).3.2.2.5 Rhyolitic tuffaceous sedimentsRhyolitic tuffaceous sediments form deposits 5 to 50 m thick of ash, fine tuff, coarse tuffand other volcanic products. Most of these deposits are featureless due to pervasive sericitealteration and abundant veins of sphalerite, tennantite, galena and pyrite (Plate 3.7a). However,34observations detailed below support an overall volcanic origin. Occasional devitrified obsidianfragments occur throughout the unit. The fragments contain small spherulites about 1 mm acrossthat show sector extinction under crossed polars. A silicified deposit of tube-pumice wasidentified (R. Allen, pers. comm., 1993) on the southern part of Section 17+98 (Figure 3.4; DDH14-9 16, 326 m or 980 feet; about 4 075 N). A 3 metre thick bed of accretionary lapiffi wasidentified at the top of the unit (Figure 3.2; DDH 14-755). The lapifli, regular effipsoidal objectswith a pancake shape, range from 2 to 10 mm across (Plate 3.7b). They often contain nucleii ofbroken quartz crystals. Dark rims around the lapilli are coats of fine grained ash. They arepervasively sericitized, but the concentric organization of pyroclasts is still visible in plane light(Plate 3 .7b). Except for the sericitic overprint, these accretionary lapilli are very similar to thosedescribed by Boulter (1987).3.2.2.6 Upper zone massive suiphide lensesUpper zone massive suiphide lenses (Plate 3.8) occur mostly at the contact between rhyolitetuffaceous sediments and the overlying quartz-feldspar porphyritic rhyolite (section 3.2.2.7).Individual lenses range from 1 to 8 m thick, and are less than 20 m wide. They are discontinuousalong strike, so it is not possible to follow most of them between exploration drill sections spaced50 to 100 m apart. The larger lenses are zoned from a sphalerite, tennantite, pyrite, galena,chalcopyrite core region to massive barite, sphalerite on the periphery of the lens. Highargentiferous tennantite contents make these lenses extremely silver rich (usually 150 grams silverper tonne but locally up to 1 000 grams silver per tonne), although gold contents are notparticularly high (1 to 3 grams gold per tonne). They are underlain by feeder zones composed ofpolymetallic veins in altered rhyolite tuffaceous sediments. The veins contain sphalerite,tennantite and quartz in a pervasively sericitized and silicified groundmass.3.2.2.7 Rhyolite flow-dome complex3gThe rhyolite flow-dome complex forms a long linear body that is over 100 m thick and atleast 200 m wide. The northern part of the flow dome has not been defined by the currentdriffing, but it appears to have been faulted down. The flow-dome is continuous for at least 600m along strike in the Battle zone and is part of the same felsic complex that overlies the H-Wdeposit. The entire flow-dome complex therefore has a known strike length of 2.5 km; it is stillunexplored at both ends.The rhyolite flow-dome complex consists of three distinct units. Individual felsic flows andintrusions within the Battle zone were distinguished and mapped based on the presence, size andmorphology of quartz and feldspar phenocrysts as it is unlikely that two successive units wouldcontain phenocrysts of the same nature and size in the same proportion (De Rosen-Spence eta!.,1979). The three members, from stratigraphically lowest to highest, are: (1) quartz porphyriticrhyolite, (ii) quartz-feldspar porphyritic rhyolite, and (iii) green quartz-feldspar porphyriticrhyolite. All rhyolite units except the dike were originally glassy, but have devitrifled to agranophyric (McPhie eta!., 1993) matrix of fine grained, roughly equidimensional, recrystallizedquartz and feldspar. All rhyolite types contain quartz and oligoclase (An22: Michel-Lévymethod). They were stained with sodium cobaltinitrite for potassium feldspar but none containpotassium feldspar as megascopic matrix grains. Phenocryst assemblages and their morphologyare described below and in Table 4.1.Quartz porphyritic rhyolite (QP) is 5 to 30 m thick, at least 75 m wide and over 250 mlong; the limits have not been tested. It occurs both within the felsic volcaniclastic sequence inthe northernmost part of the Battle zone (Figure 3.3; Section 15+85E) and in andesite below theGap massive sulphide lens (Figure 3.2; Section 13+72E). Contact relationships between the QPrhyolite and other lithologic units are not clear in drill core. However, its occurrence in lithologicunits of different ages suggests an intrusive relationship. The QP rhyolite is probably a shallowlevel sill that marks the beginning of effusive (rather than explosive) emplacement of rhyolite.3’,QP rhyolite is white to pale grey-green (Plate 3 .9a) and contains 1 to 2 % subhedral toeuhedral hexagonal and square quartz phenocrysts about 1 mm in diameter (Plate 3.9ai). Tracesericite-altered feldspar phenocrysts less than 1 mm long are also present. The quartz crystalshave sharp boundaries; rare crystals are embayed and some have quartz-feldspar coronas. Thematrix has a granophyric texture and is composed of fine grained, roughly equidimensional,recrystallized quartz and feldspar. Locally, the matrix is weakly flow-banded with pyrite andsericite aligned along the flow-bands. This unit is intensely sericitized due to its proximity to oreforming hydrothermal systems. Hydrothermally altered flows are easily mistaken for tuffaceouschert units but are distinguishable from chert by the presence of quartz phenocrysts and a sericiticsheen on broken surfaces.Square quartz phenocrysts are characteristic of this unit. They were probably formed aftercristobalite, the high temperature tetragonal polymorph of Si02. These, the paucity of otherphenocrysts and the presence of glassy autobreccia fragments indicates that this may have been avery hot, glassy, shallow level intrusion. This may have important implications for metallogenesisin H-W horizon (Chapter 8).Quartz-feldspar porphyritic rhyolite (QFP) is the most abundant rhyolite type within theBattle zone flow-dome complex. It is between 30 to 60 m thick in the central and northernregions of the Battle zone. To the south, between 4 200 and 4 100 north (Figures 4.2 to 4.4), theunit thins into lobes between 5 and 10 m thick. The upper contact with overlying andesite flowsand volcaniclastics is rubbly. The lower contact sharply overlies the tuffaceous rhyolite sedimentsor upper zone massive suiphides.Morphological variations within the QFP are consistent with it being a volcanic flow ratherthan a sill, however, near Section 17+98E (Figure 3.4), the flow front has burrowed into theunderlying rhyolite tuffaceous sediments. Coarse deposits about 3 m thick of rounded QFPfragments between 5 mm and 30 cm across occur locally at the top of the flow-dome complex.This upper unit is most likely a reworked flow-top breccia. It indicates that the QFP was exposed37to erosion, therefore it was not intrusive. A sharp contrast in alteration intensity and stylebetween the QFP (intensely sericitized) and the overlying hangingwall andesite (moderatelysausseritized) further supports a time gap between eruption of the QFP and emplacement of thehangingwall andesite. Elsewhere, the top 5 to 15 m of the QFP are clark grey, strongly flowbanded and altered to sericite. These areas probably represent originally glassy margins. At theflow front (about 4 100 N, Figures 4.2 to 4.4), this glassy margin is flow-folded (Plates 4.9c andci). The flow-front is characterized by wormy textured sub-microscopic to macroscopic flow-folds up to 20 cm across in autobrecciated rhyolite. The flow-bands that define the flow-foldsconsist of aligned sericite and pyrite grains. Many flow-bands wrap around flow-bandedautobreccia fragments. These fragments are rotated with respect to each other, giving this unitchaotic appearance. Massive, white-grey to pale green stony rhyolite with moderate to intensequartz-sericite alteration comprises the center and base of the QFP flow. Flow banding is presentthroughout, but is concentrated at the base. Flow bands are laminar in the central and basal partsof the flow, and contain aligned phenocrysts and pyrite grains (Plates 4.9b).Petrographically, the QFP is characterized by about 8 % sericite-carbonate altered feldsparphenocrysts, about 3 mm long, and about 4 % euhedral to slightly embayed quartz phenocrysts, 1to 5 mm in diameter, in an aphanitic and weakly flow-banded matrix (Plates 4.8b and b1).Locally, feldspar crystals grow around quartz crystals, indicating that quartz crystallized first.Both hexagonal and square (after cristobalite) cross-sections of quartz are apparent in thinsection. Some crystals have thin rims of intergrown quartz and feldspar. Accessory apatite andzircon(?) also occur.Green quartz-feldspar porphyritic rhyolite (GQFP) forms flows 5 to 50 m thick that occuron top of the QFP and the felsic tuffs overlying the Gap massive suiphide lens (Figures 4.1, 4.3and 4.4). Most of the GQFP occurs in the northern part of the Battle zone, although a detachedlobe between 5 and 20 m thick was mapped towards the south on Section 15+85E (Figure 3.3,about 4 100 N). The upper contact with the hangingwall andesite is rubbly and somewhat3reworked; this contact most likely represents a brecciated flow-carapace. Fragments of GQFP aresubangular and range from mm across to larger blocks up to 50 cm (?) across (the size is difficultto estimate in drill core samples). The degree of rounding is less than that observed for fragmentsin the QFP flow-breccia carapace. This suggests the GQFP is less eroded than the QFP andtherefore younger. Locally, GQFP fragments are scoured into the overlying andesite flows andflow breccias. The lower contact with the QFP is sharp except where it is obscured by laterhydrothermal alteration. Generally, the contact is identified by a colour change; the GQFP has adistinctive apple green to forest green colour (Plate 3 .9d), whereas the QFP is dark to pale grey.These contact relations support the interpretation that the GQFP is a flow rather than a sill (seeabove).TABLE 3.1. MINERALOGY OF INDIVIDUAL MEMBERS WITHIN TBE RHYOLITE FLOW-DOMECOMPLEX, BATILE ZONE, BUTI’LE LAKE MINING CAMP.Quartz-porphyritic Quartz-feldspar Green quartz-feldsparrhyolite (QP) porphyritic rhyolite porphyritic rhyolite(QFP) (GQFP)Plate 4.9a,a1 4.9b,b1c,c 4.9d,d1Quartz phenociysts 2%, 0.5-2 mm 4%, 0.5-5 nun 6%, 0.5-6 nunMorphology of quartz Subhedral to euhedral Euliedral to slightly Strongly embayed withphenociysts tetragonal cristobalite(?) embayed dominantly rims of quartz andcrystals hexagonal crystals, 1% feldsparcristobalite(?) crystalsFeldspar’ phenocrysts <1%, <0.5 mm 8%, 3 mm 10%, 1-10 nunHornblende None None RarephenociystsAccessory minerals Rare Apatite, zircon? MagnetiteMatrix Very fine grained quartz Fine grained quartz and Fine grained quartz,and sericite, perhaps feldspar feldspar and chloriteafter feldspar microlites‘All rhyolite units contain oligoclase of composition An22,determined by the Michel-Levy method. All feldspars are altered tosericite and carbonate, but the degree of alteration decreases with decreasing age (from left to right).The GQFP contains about 6% subhedral to rounded quartz phenocrysts, 0.5 to 6 mm indiameter, and 10% feldspar phenocrysts, ito 10 mm long (Plate 3.9d1). Many of the quartzcrystals are deeply embayed and are rimmed with intergrown quartz and feldspar, Square quartzcrystals are notably absent. Feldspars are altered to sericite and carbonate, but less so than in theQP and the QFP. The matrix is mostly fine grained granophyric textured quartz and feldspar.Chlorite, possibly replacing hornblende, and disseminated magnetite also occur in the matrix.Locally, magnetite is altered to hematite and the GQFP is purple rather than green.3.2.3 Hangingwall AndesiteHangingwall andesite is dark green, slightly amygdaloidal, and contains about 25 % feldsparand 1% pyroxene phenocrysts. The feldspar crystals are 0.3 to 2 mm long, and may occur asglomerocrysts or freely in the matrix. Most feldspar crystals are moderately to intensely altered tocalcite and epidote. Chlorite replaces rare pyroxene phenocrysts. The amygdules are elongate tolenticular, 0.3 to 2 mm long, and are filled with quartz, epidote and magnesian chlorite. Thematrix is pervasively altered to magnesian chlorite and clinozoisite. Trace amounts of magnetiteoccur in the matrix; locally these are altered to purple hematite.Most of the hangingwall andesite occurs as flows (30%) and related flow-breccias (60%).Approximately 10 % of the hangingwall andesite consists of inter-flow sedimentary units.Sedimentary units may be well sorted, andesite-dominant greywacke, or more rarely, poorlysorted polylithic breccias.A typical andesite flow consists of 2 to 5 m of massive, slightly vesiculated andesite withabout 3 m of hyaloclastite breccia on the top of and marginal to the flow. Typical andesite flowbreccias are composed of poorly sorted, angular fragments with arcuate clast boundaries; many ofthe fragments also have in situ (jigsaw-fit) breccia textures (Plate 3.10) characteristic ofsubaqueous quench fragmentation (McPhie et a!., 1993). The contact between the underlying HW horizon and hangingwall andesite is generally sharp, although fragments of QFP and GQFP arecommonly scoured from the flow-dome complex and incorporated into the overlying andesiteflows and flow breccias. Hydrothermal alteration that affects the Price formation and the H-Whorizon does not extend into the hangingwall andesite, therefore, there is a time gap betweenhydrothermal alteration and deposition of the hangingwall andesite.L403.2.4 DikesMost dikes in the Battle zone are mafic. Three distinct types of mafic dikes have beenrecognized: (i) light green, feldspar-phyric, trachytic mafic dikes, (ii) dark green augite andfeldspar phyric mafic dikes, and (iii) andesite dikes. Most of the light green dikes are intenselyaltered to an epidote-fuchsite-chlorite-carbonate assemblage and have irregular, quartz-carbonateveined contacts with the country rock. Some dikes have pink quartz-carbonate filled amygdules.Dark green augite-phyric dikes may be fresh or altered to epidote, fI.ichsite and chlorite; they tendto have sharp contacts. Andesite dikes are dark blue-green, weakly feldspar porphyritic andunaltered. All of the mafic dikes cross-cut H-W horizon and the hangingwall andesite.One feldspar-quartz-hornblende rhyolite porphyry dike (QFPD) was identified in the Battlezone. It has sharp, quenched contacts with the QFP and clearly cross cuts the QFP as shown onFigure 3.2 (about 4 200 N). This unit is crystal rich with 35% 2 to 3 mm long sericite-carbonatealtered feldspar crystals, 7% quartz eyes up to 7 mm in diameter, and 2% chlorite-alteredhomblende crystals (Plate 3.1 la). The quartz eyes are partially resorbed and have relatively thick(about 0.3 mm) quartz-feldspar coronas. The quartz in the coronas is optically continuous withthe enclosed quartz grains (Plate 3.1 1a). The matrix is significantly coarser in the QFPD than inother rhyolite types, and consists of intergrown feldspar and quartz. Chlorite and accessorymagnetite occur in the matrix, giving this unit a mossy green appearance. The QFPD is clearlyyounger than all other units in H-W horizon. It may be related to rhyolite units in the upper Myraformation, Jurassic intrusive activity or Tertiary events.Plate 3.1. Priceformation. Dime is 8 mm in diameter. (a) In situ andesite hyaloclastite (DDH14-754, 340 m or 1116 feet). Large olive green fragments contain 10% quartz-chlorite filledamygdules about 0.5 to 10 mm across. Pale green grains are sausseritized feldspar. Dark green-black fragments are devitrifled volcanic glass that have been partially replaced by pyrite. (ai)Photomicrograph of quartz-chlorite filled amygdules and a glomerocryst of sausseritized feldspar(DDH W190, 823 m or 2700 feet; plane light).Plate 3.2. Main Battle massive suiphide lenses. (a) Chalcopyrite rich ore from the basal part ofthe sulphide lens (DDH 14-75 1, 323.4 m or 1061 feet). (b) Banded pyrite and dark sphaleritefrom the middle part of the sulphide lens (DDH 14-75 1, 321.3 m or 1054 feet). (c) Pale yellowsphalerite from the top of the suiphide lens (DDH 14-751, 318.8 m or 1046 feet). Sample, almostpure sphalerite, contains only 5% pyrite and 10% gangue. (d) Interbedded sphalerite, pyrite andshale from top of the sulphide lens (DDH 14-753, 280 m or 920 feet). Bedding to core axisangles in the suiphide unit are the same as in the overlying fine rhyolitic tuffaceous deposits.Chalcopyrite and galena are concentrated in dewatering pillar structures that are perpendicular tothe beddingPlate 3.3. Gap massive suiphide lens. (a) Pyritic massive suiphide (DDH 14-757, 223.7 m or 734feet). Mineralogy is: pyrite> sphalerite> bornite > anilite. (b) Baritic massive sulphide from theupper part of the Gap lens (DDH 14-757, 200 m or 656 feet). Mineralogy is: sphalerite> barite> pyrite> quartz > galena> tennantite. Barite in centre shows convex surfaces that face up-hole(to the right).—‘-4 C‘Iq3Plate 3.4. Fine rhyolitic tuffaceous deposits. Dime is 8 mm in diameter. (a) White, distinctivelylaminated chert (DDH 14-751, 306 m or 1004 feet). Quartz and suiphide veins cross-cutlaminations at 90°. (b) Fine grained rhyolite tuffaceous sandstone (DDH 14-75 1, 291 m or 953feet). Dark grey layer on the left (base) is mostly flattened pumice fragments with 10% 1 mmquartz crystals. Pale grey layer is fine grained, silicifled rhyolite tuff with quartz veinsperpendicular to bedding. Layer at right (top) is coarse grained rhyolite tuff. It contains 0.5%quartz crystals and 2% black devitrifled pumice fragments.Plate 3.5. H-WmaJlc sill. (a) Massive sill (DDH 14-753, 268 m or 879 feet). The sample ispink due to pervasive sericite-pyrite alteration. (b) Swirly yellow-brown and white peperite fromthe top of sill (DDH 14-753, 263 m or 863 feet). White material is siliceous and containseuhedral quartz crystals; it is most likely incorporated felsic tuffaceous sandstone from overlyingunits. The yellow-brown material is palagonite.Plate 3.6. Coarse rhyolite pyroclastic deposits. (a) Pumiceous lapilli tuff (DDH 14-753, 254 mor 834 feet) contains 15% pale grey to white weakly quartz-porphyritic to aphanitic rhyolitefragments in a black, compacted, pumiceous, crystal-rich matrix with 10% 1 to 2 mm quartz eyesand 15% 2 mm feldspar crystals. (ai) Photomicrograph of pumiceous lapilli tuff(DDH 14-906,284 m or 852 feet). Sample contains a fine grained lithic fragment in the center. Surroundingmaterial is sericite with 10% broken quartz crystals. (b) Rhyolite tuff with pumice blocks (DDH14-753, 252 m or 828 feet). Pumice blocks are in a fine grained, medium-bedded rhyolite tuff.AL‘15Plate 3.7. Rhyolite tuffaceous sediments. Dime is 8 mm in diameter. (a) Tuffaceous sandstone(DDH 14-750, 260 m or 854 feet). This specimen is intensely altered by polymetallic quartzsericite veins, but relict sedimentary bedding is still visible. (b) Photomicrograph of a 3 millmetrelong accretionary lapillus (DDH 14-754, 251 m or 754 feet; plane light). Although the sample ispervasively sericitized, the concentric organization of pyroclasts is plainly visible. Note thecentral grain of broken quartz which formed the original nucleus.Plate 3.8. Upper zone massive sulphide lenses (DDH 14-723, 217.9 m or 715 feet). Specimencontains sphalerite > tennantite> pyrite> galena> chalcopyrite and grades over a kilogram ofsilver per tonne.Plate 3.9. Rhyoliteflow-dome complex. (a) Quartz-porphyritic rhyolite (QP) with ito 2% 1 mmquartz eyes (DDH 14-957, 266 m or 875 feet). A small spherulite about 2 mm across is on thebottom right of this specimen. (a1) Photomicrograph of the QP rhyolite (14-757, 276 m or 905feet, crossed polars). This photo shows characteristic euhedral to subhedral square quartzphenocrysts about 0.8 mm across in an aphanitic groundmass. Inset is a photograph of aspherulite 0.13 mm across showing a radial extinction pattern (crossed polars). (b) Quartzfeldspar porphyritic rhyolite (QFP) from the base of the flow-dome complex (DDH 14-753, 221.9m or 728 feet). Sample contains 3-5% ito 2-mm quartz eyes and 15% 1 to 2-mm sericitizedfeldspar. Flow-bands are marked by trails of pyrite grains. (b1) Photomicrograph of the QFPrhyolite (14-905, 232 m or 760 feet, crossed polars). Sample contains subhedral quartz grains 1mm across, and albite grains 0.4 to 1.5 mm long.b9b,-J97Plate 3.9 continued. . . Dime is 8 mm in diameter. (c) Autobrecciated, flow folded QFP from themargin of the rhyolite flow-dome complex (DDH 14-756, 242 m or 794 feet). (ci)Photomicrograph of flow-folded QFP rhyolite (same as above, crossed polars). Pyritic (opaquegrains) flow-bands mark the flow-folds. (d) Green quartz feldspar porphyritic rhyolite (DDH 14-904, 284 m or 932 feet) is characterized by abundant albite phenocrysts in a green matrix. (d1)Photomicrograph of GQFP rhyolite (DDH 14-904, 188 m or 618 feet, crossed polars). Embayedquartz phenocrysts and large feldspar crystals are characteristic of this rock.Plate 3.10. Hangingwall andesite. (a) hyaloclastite breccia (DDH 14-720, 169 m or 556 feet).Scale is in cm. Cuspate fragments of andesite that can be jigsawed together are characteristic ofthis unit. (b) Photomicrograph of a hangingwall andesite flow (DDH 14-9 17, 245 m or 803 feet).Sausseritized feldspar grains occur in a pervasively chloritized matrix.Plate 3.11. Feldspar quartz hornblende rhyolite porphyry dike (QFPD; DDH 14-753, 221.8 m or728 feet). (a) Massive, green-grey QFPD with 35% 2 to 3 mm feldspar crystals and 10% 1 to 3mm quartz eyes. Green colour is due to chlorite alteration of mafic minerals in the matrix. Thisunit cross-cuts the QFP units described above. (a1)Photomicrograph of QFPD (DDH 14-753,221.8 m or 728 feet, plane light). Rounded quartz phenocryst has an optically continuous coronaof quartz and feldspar. Chlorite altered mafics occur as interstitial blobs in the matrix. Smallopaque grains are mainly magnetite.—_ -—F:r.z4€13.3 INTERPRETATION OF THE BATTLE AND GAP ZONE GEOLOGY3.3.1 IntroductionA number of significant geological features were described in section 3.2 that help toconstrain the depositional environment. These include basement topography (Figure 3.1), synvolcanic and synmineral faults (Figures 3.2 to 3.4), extensive deposits of chert (section 3.2.2.2),welded pumiceous lapilli tuff (section 3.2.2.4), accretionary lapilli (Plate 3 .7b), and a mappablesequence of spatially and genetically related intrusions and flows within the rhyolite flow-domecomplex (section 3.2.2.7). In this section the writer attempts to incorporate all of these significantfeatures into a comprehensive evolutionary model for the Battle and Gap zones that is presentedin Figures 3.5a to g.3.3.2 Evolution of massive suiphide lensesMost massive sulphide lenses occur at the base of the felsic H-W horizon, immediatelyoverlying the Price formation. Price formation is a sequence of massive to pillowed flows andassociated breccias that was deposited subaqueously during a series of non-explosive, effusiveevents. The unit is poorly to moderately vesiculated, indicating that the hydrostatic pressure wassufficient to prevent explosive exsolution of volatiles from the magma. Unfortunately, there is nosimple correlation between the amount ofvesicles and water depth. An analysis of submarinebasalts by Dudás (1983) indicates the solubility-pressure-volume relations of volatiles in basalticmelts can allow vesicles to develop at any water depth.Subsequent rifting of the Price andesite formed the Buttle Lake camp basin with minimumdimensions of 3 by 10 km (Juras, 1987). Block faulting within the basin was contemporaneouswith the first cycle of sulphide deposition along the strike of the rift zone, represented by the mainBattle lens, H-W lens, and probably, the Gap lens (Figure 3. 5a). The interpretation that the Gaplens is correlative with Battle and H-W is based on Section 13+72E (DDH 14-757; Figure 3.2)50This figure shows that the footwall of the Gap zone is dominantly altered andesite, probably Priceformation, with lesser intrusive(?) quartz porphyritic (QP) rhyolite (section 3.2.2.7). Anotherpossibility is that the footwall contains intrusions or flows of the H-W mafic sills.The main Battle massive sulphide lens was deposited in a fault-bounded basin within thePrice andesite. Only the north bounding fault is preserved at 4 250 N (Figures 4.2 and 4.3,respectively); the southern edge of the basin has been faulted away by the post-mineral ‘Flat Fault’(C. Pearson, Westmin Resources, pers. comm., 1993). The 4 250 N fault is synvolcanic becauseit does not displace strata overlying the Price andesite and is synmineral because: (i) the massivesuiphide lens thickens close to the fault, and (ii) the alteration intensity in the Price andesiteincreases as the fault is approached (see Figure 6.1). The massive sulphide lens itself is tabular,and ranges from 130 to 210 m wide and 4 to 25 m thick. Open at both ends, it has a minimumstrike length of 500 m (S. Juras, pers. comm. 1993). The south trough is a 30 to 40 metre widesub-basin developed on the south side of the main lens that accumulated a 15 to 25 m thickness ofmassive sulphide. It is shown on Section 15+85E (Figure 3.3) where it is only 15 m deep andSection 17+98E (Figure 3.4) where it is 25 m deep. In Section 15+85E (Figure 3.3), the southtrough is bounded by a synvolcanic normal fault at 4 050 N and a fault that was most likelysymnineral, but also with later movement, at 4 100 N. In Section 17+98E (Figure 3.4),displacement on the 4 050 N fault increases.The Gap massive sulphide lens (Section 13+72E; Figure 3.2) is 20 to 30 m high, 40 to 50 mwide and 250 m in strike length (Pearson, 1993). It is bounded on both sides by faults that mayhave been synmineral, but which now display later movement. In particular, the northernmostfault on Section 13+72E (Figure 3.2; about 4 300 N) probably has significant post mineral strike-slip displacement (S. Juras, 1993, pers. comm.). The geometry of the Gap massive suiphide lenssuggests that it also was deposited in a narrow fault bounded basin.Synmineral normal faults provided conduits for metal rich hydrothermal fluids, which uponreaction with sea water near the sea floor, deposited suiphide mud. Plate 3.2d shows beddedsuiphide that may represent what the sulphide lens looked like when it was first deposited. Thefault bounding the horst to the north at 4250 N in Section 13+72E and Section 15+85E (Figures3.2 and 3.3) was the feeder for the main Battle massive sulphide lens in the western part of theBattle zone. The southernmost synmineral fault at 4050 N in Section 15+85E and Section17+98E (Figures 3.3 and 3.4) was probably the feeder for the south trough part of the massivesuiphide lens. Continued reaction of the mud with hydrothermal fluids converted most of thesedeposits to pyrite and chalcopyrite rich cores with sphalerite-dominant upper and peripheral zones(Chapter 6).3.3.3 The origin of chert: exhalite or volcanic?Fine rhyolitic tuffaceous deposits contain 1 to 5 metre thick deposits of chert thatcommonly, but not exclusively, occur immediately above main Battle zone massive sulphidelenses. Tuffaceous chert forms a continuous blanket over the main Battle massive sulphide lensnear Section 1 5+85E (Figure 3.3). However, the distribution of cherty deposits is more erratictoward Section 13+72E and Section 17+98E (Figures 3.2 and 3.3). Section 13+72E (Figure 3.2)has three cherty horizons. Section 17+98E (Figure 3.4) shows only sporadic distribution of chertaround the main sulphide lens, and none associated with the south trough, the thickestaccumulation of massive sulphide.There are two likely origins for the tuffaceous chert horizons; they may be exhalites or theymay be silicified felsic volcanic ash and tuff deposits. If they are exhalites, then they aregenetically and spatially related to massive suiphides. If they are of purely volcanic origin, thentheir occurrence on top of the massive sulphides is accidental, and they should be interpreted asthe basal unit associated with the onset of felsic volcanism.6ZExhalites are defined as distal and proximal, contemporaneous and late-stage products ofthe same hydrothermal systems responsible for forming massive sulphide deposits(Kalogeropoulos and Scott, 1983). They have two components, elastic and chemical. The elasticcomponent may be volcaniclastic, epiclastic or pelagic. The chemical component is dominantlyquartz, associated with either iron oxides or iron suiphides. Manganese oxides, iron richsmectites, sericite, base metal mineralization and anomalous amounts of gold, silver, cobalt andnickel may also be present (Kalogeropoulos and Scott, 1983).Battle zone cherts (Plate 3 .4a) are probably not exhalites because: (i) they do not containsignificant amounts of iron sulphides or oxides, (ii) they are not enriched in gold, silver,manganese, cobalt or nickel (M. Robinson, unpublished inductively coupled plasma data fromChemex Labs Ltd., Vancouver, British Columbia, 1993), and (iii), they have the same immobileelement chemistry as the overlying rhyolite (Chapter 5). Compared to the exhalites describedabove, Battle zone cherts are relatively pure quartz with relatively minor contamination bysulphides (chemical analyses are in Table 5.2.).3.3.4 Rhyolite volcanic sequenceThe rhyolite volcanic sequence in the Battle zone (Figure 3.1) is composed of: (i) finerhyolitic tuffaceous deposits, (ii) coarse rhyolite pyroclastic deposits, (iii) rhyolite tuffaceoussediments, and (iv) the rhyolite flow-dome complex. The relationship among these units isexplored in this section, and a model for their emplacement is in Figure 3. Sb to g.Fine rhyolitic tuffaceous deposits, including the Battle zone chert, represent the initialphreatoplinian outburst associated with the onset of felsic volcanism (Figure 3. 5b). Involvementof water at the edifice would have caused a high degree of fragmentation, thus ensuring the finegrained nature of the deposits. Transport of ash to the Battle zone most likely occurred viaturbidity currents, but also possibly by settling through the water column. Silicification of thebasal part of the tuffs could have been accomplished by continued circulation of hydrothermalS3fluids associated with massive suiphide deposition throughout the sulphide mound and theoverlying felsic pile.A change in eruption style is marked by the widespread semi-continuous blanket ofpumiceous lapilli tuff 2 to 25 m thick throughout the Battle zone (section 3.2.2.4). This lapilli tuffis thickest towards the southeast part of the Battle zone (Section 17+98; Figure 3.4) where it fillsthe topographic low above the south trough, and thins to the northwest (Section 13+72; Figure3.2); the tuff also extends into the H-W mine area, 1 km to the east. Classic microscopic weldingtextures within this unit are documented by Juras (1987, 1986). These include eutaxitic texture,baked accidental lithic fragments and sulphide fragments of pyrrhotite. As pyrrhotite is notpresent in any of the massive sulphides, Juras (1987) argues that pyrrhotite formed from pyritewithin the suiphide fragments when they were baked. All of these characteristics suggest that thepumiceous lapilli tuff was emplaced as a hot pyroclastic flow (Cas and Wright, 1988).The occurrence of subaqueous pyroclastic flows is highly controversial. One view is that itis not possible for hot flows to originate by eruptions beneath water, or to flow from land intowater, without mixing with the water in sufficient quantities to decrease the temperature belowthe temperature needed for welding. In addition, turbulent mixing with water would tend todestroy the eruption column. However, it is possible that a voluminous ‘boiling over’ type oferuption would be extruded at rates fast enough to produce a flow protected from heat loss andturbulence by a carapace of steam (Fisher and Schminke, 1984). Alternatively, a pyroclastic flowcould have a subaerial origin, but subsequently be moved and deposited underwater. Sparks et al.(1980) showed that welding is theoretically likely to occur in a subaerially produced flow once ittravels below the air-water interface.The pumiceous lapilli tuff is crystal rich compared to the rhyolite flows in the Battle zone.It contains over 10% large broken quartz crystals 0.5 to 10 mm across in the matrix (section3.2.2.4). Feldspar was not observed in the pumiceous component in this unit of the Battle zone.If originally present, it was completely altered to sericite. Feldspar was observed, however, in lessaltered rocks elsewhere on the property (Juras, 1987). The unique phenocryst assemblage maysuggest the magma for the pumiceous component had a different source than the other rhyoliteflows. A simpler explanation is that the pyroclastic material was sorted in the eruption column.Turbulence and convective circulation in eruption columns tend to winnow the fine portion ofglassy ash into the upper part of the column (see above; Cas and Wright, 1988). Crystals andlithics are residually concentrated in the main body of the eruption column and incorporated intothe pyroclastic flow.Using the above model, the pumiceous lapilli tuff member of the coarse rhyolite pyroclasticdeposits represents the high concentration part of a welded subaqueous pyroclastic flow. Itcontains cognate lithic fragments of QP (section 3.2.2.4), therefore a likely mechanism forgenerating the flow is by an explosive eruption column (McPhie et a!., 1993) preceding eruptionof the QP. Vitric ash carried in a convective column rises above the moving pumice flows (Figure3. 5c). The loss ofvitric ash would result in the complementary increase in the amount of crystalsand lithics observed in the pumiceous lapilli tuff. Its relatively high density would have allowed itto maintain most of its integrity upon entering the water. Overlying rhyolite tuffwith pumiceblocks (section 3.2.2.4) probably formed by water-settled suspension deposition of the part of thepyroclastic flow that was blown apart by steam explosions upon entry into the water (Figure3.Sc). Pumice blocks would have floated on the surface of the ocean before becomingwaterlogged and sinking into the sediments below (Figure 3.5d).Deposits from the accompanying ash cloud are represented by the rhyolite tuffaceoussediment unit (Figure 3.5d). The tuff is crystal-poor compared to underlying coarse rhyolitepyroclastic deposits. Although largely featureless due to pervasive post-depositional alteration, itis characterized by the presence of small, devitrifled, glassy fragments throughout, and localdeposits of tube pumice and accretionary lapilli (Plate 3.7b). Accretionary lapilli are oftengenerated in the relatively dilute ash clouds that are associated with pyroclastic flows (Figure3.5e), and deposited in ash-rich bed at the tops of related flow deposits (McPhie et a!., 1993).This is what appears to have occurred in the Battle zone. The significance of the accretionarylapilli is that they imply a subaerial eruption column as there are no documented cases ofaccretionary lapilli actuallyforming in the submarine environment. However, they can withstanda substantial degree of reworking by normal sedimentary processes (Boulter, 1987).A hiatus between deposition of the rhyolite tuffaceous sediments and eruption of therhyolite flow-dome complex is marked by deposition of upper zone massive suiphide lenses(Figure 3.5f). Feeder zones are characterized by widespread stockworks of polymetallic veins insericitized rhyolite tuffaceous sediments. The occurrence of veins rather than disseminationsimplies lithiflcation of the underlying tuffaceous units occurred prior to deposition of the upperzone lenses.Intrusion of quartz porphyritic rhyolite into the Price andesite and rhyolite pyroclastics as ahot, shallow level sill marked the transition from explosive to effusive volcanism. Extrusion of thequartz feldspar porphyritic rhyolite followed by the green quartz feldspar porphyritic rhyolite overthe Battle and Gap zones ended the felsic eruptive cycle (Figure 3.5g). The rhyolite flow domecomplex is elongate in the northwest-southeast direction, and thickens to the northeast. Theinferred flow direction is to the southwest, with a vent source to the northeast. It has the elongategeometry of a fissure eruptive system, but the location of the feeder dike is not known.Figure 3.5. Series of diagrams showing a depositional model for H-W horizon in the Battle zone.The volcanic arc-remnant arc setting was established by Juras (1987), and forms the basis for thefigures. The diagram is not to scale, however, the distance between the volcanic arc and remnantarc is between 10-25 km, the thickness ofH-W horizon in Figure 3.5g is 15-200 m, and the widthof the Battle zone is about 1.5 km.(a) The Battle zone massive sulphide lens was deposited in fault-bounded basins within the Priceandesite. The Gap zone, also shown in a fault-bounded basin, may have contained other unitsbesides Price formation in the immediate footwall at the time of deposition. Heated sea water,and possibly magmatic water, circulating through the volcanic pile was discharged throughsynvolcanic (and synmineral) faults, where it reacted with cold sea water and deposited suiphidemud. The occurrence of a felsic magma chamber is inferred from the presence of rhyolite volcanicdeposits but has not been intersected in drill core.a)Arc—marginalriftingandmassivesuiphidedepositionSeaLevelButtlelakecampbasin(riftedarcmargin)PriceandesiteGapRhyofltetuftwithpumiceblocksPumiceouslophfltuftBattlezoneApexoffelsicmagmachamberFigure 3.5. Series of diagrams showing a depositional model for H-W horizon.. . continued.(b) Initial phreatoplinian outburst from the volcanic arc region. Fine rhyolitic tuffaceous deposits,commonly cherty due to post depositional silicification, were deposited by both water suspensiondeposition of fine tuff and by turbidity currents.RhyottetuftwithpumiceblocksPumiceousOpillitub)InitialphreatoplinianeruptionanddepositionofthefinerhyolitictuffaceousdepositsSeaLevelIAir—fallPriceandesiteButtlelakecampbasin(riftedarcmargin)BoWemossivesulphidelens 0 1__ApexoffelsicmagmachamberVVVIvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv‘0Figure 3.5. Series of diagrams showing a depositional model for H-W horizon. . . continued.(c) Deposition of the pumiceous lapilli tuff may have been initiated by collapse of the eruptioncolumn. Crystals and lithics are sorted into the high density part of the flow, and vitric material iswinnowed into a convective column above the vent. Lower clouds of ash rise above the movingpumice flows and travel across the water surface. Secondary steam explosions disrupt part of theflow when it enters the water.c)Generationofapyroclasticflowanddepositionofthepumiceouslapillituff--++++++Rhyoliteflow—domecomplex zonemassiveaVltncashcomponentVitricRhyolitetuffufthpumiceb’ocksPumiceousiopilktuffSeaLevelPriceandesitev_v_v_v‘VVVvivvvv’lVVvvivvvv’vvvvI•:vvvv’ivv)BottlezoneButtlelakecampbasin(riftedarcmargin)Apexoffelsicmagmachamber‘2Figure 3.5. Series of diagrams showing a depositional model for H-W horizon. . . continued.(d) Water settled suspension deposition of tuff and pumice blobs. Accretionary lapihi may form inthe eruption column.d)Water—settledsuspensiondepositionofcoarsetuffandpumiceblobs+Rhyoliteflow—dome÷÷comp’ex+++•••:.••.•••::Accretionarylqpilli0•••••VitricashArcSeaLevelPriceandesiteBattlezoneApexoffelsicmagmachamberButtlelakecampbasin(riftedarcmargin)‘1Figure 3.5. Series of diagrams showing a depositional model for H-W horizon.. . continued.(e) Collapse of the eruption colunm and deposition of the rhyolite tuffaceous sediments.Turbidity currents, water settled suspension deposition and possibly debris flows becomeimportant processes.e)Accretionarylapilli•DebrsflowsCollapseoftheeruptioncolumnanddepositionoftherhyolitictuffaceoussedimentsSeaLevelTurbidityurrents_—PriceandesiteRhyolitetuffwithpumiceblocksPurniceouslapillituffButtlelakecampbasin(riftedarcmargin)ApexoffelsicmagmachamberL7Figure 3.5. Series of diagrams showing a depositional model for H-W horizon. . . continued.(f) Deposition ofupper zone massive suiphide lenses.f)DepositionofupperzonemassivesuiphidelensesSeaLevelPriceandesiteGapzoneRhyolitetuftwithpumiceblocksPumiceouslopillituffButtlelakecampbasin(riftedarcmargin)Battlezone1++\/+•i1+++1+++++++I++4-4-+1÷++++1÷+÷÷1÷++++4I4-++4-++I1+++++-4Apexoffelsicmagmachamber‘BFigure 3.5. Series of diagrams showing a depositional model for H-W horizon. . continued.(g) Eruption of felsic flows from an under water fissure ends the cycle of felsic volcanism.g)Extrusionoftherhyoliteflow—domecomplexSeaLevelQuarz—1eklsparPriceandesiteRhyolitetuffwithpumiceblocksPumiceousspilttuffBattlezoneButtlelakecampbasin(riftedarcmargin)Apexoffelsicmagmachamber7cCHAPTER 4PRIMARY IGNEOUS LITHOGEOCHEMISTRY4.1 iNTRODUCTIONGeochemistry is used in this chapter to: (i) c1assit,r the volcanic flow rocks in the Battlezone, (ii) determine the magmatic affinity of the Price andesite and H-W horizon rhyolite, and (iii)characterize the primary chemical variations due to rock forming processes within the Priceandesite and the rhyolite flow-dome complex of H-W horizon. Typical analyses of volcaniclasticrock types, including chert, are also reported in this section (Table 4.1). All rock units in thePrice formation and H-W horizon of the Myra formation throughout the Buttle Lake mining camphave been altered by low-grade metamorphism, most have also been affected by weak to stronghydrothermal alteration. To assess the primary igneous geochemistry, least altered samplesrepresenting the fbll range of compositions were selected (Table 4.1). These samples containminimal amounts of alteration products such as sericite, quartz, calcite, chlorite and sulfide.Unaltered samples of Price andesite, however, were not available from the Battle zone as theextent of hydrothermal alteration reaches beyond the deepest drill holes. Thus, data from Juras(1987) for five samples from the Price formation are used. Additional data for felsic flows withinH-W horizon are also from Juras (1987).4.2 METHODOLOGY AI1]) ANALYTICAL ERRORRock samples were analyzed in three batches over a two year period. The first batch wascollected by A. Hamilton in 1992 from Section 15+85E. The second and third batches werecollected by the author in 1993. All the rock samples were collected and prepared according tothe procedures outlined in Appendix A. The analyses were done at X-Ray Assay Laboratories,Don Mills (1992 samples), Ontario and at Geochemical Laboratories, Earth and PlanetarySciences, McGill University, Montreal, Quebec (1993 samples). Detection limits, analytical errorsand laboratory are detailed in Table A. 1. In general precision of XRF analyses (Table A.2) isbetter than 2% for major elements except K20, which is precise to within about 5%. Errors fortrace element analyses are variable. Trace elements Ba, Rb, Sr, Zr, Th, U, Cr, V and Zn haveacceptable errors of less than 10%. Ni, Co, Cu, Pb, Y and Nb have errors between 20 and 70%.Y analyses for the first batch were discarded because they were all around the detection limit. Crvalues for siliceous units are suspect due to probabit chromium contamination due to sampleprocessing.4.3 ROCK CLASSIFICATION AND MAGMATIC AFFINITY4.3.1 Mafic RocksAnalyses from the Price andesite (Table 4.1; samples 229WR, P 122D, D2 108, D2 114,D2214, P 1326) and hangingwall andesite (13OWR) plot as andesite in Figure 4. la and as calcalkaline basalt in Figure 3.2b (one sample from the Price andesite plots in the high magnesiumtholeiite field). The Price andesite also contains about 0.8% Ti02,which is typical of orogenicandesites (Gill, 1981). All the samples have a caic-alkaline affinity on a MnO/Ti02/PO5discrimination diagram (not shown; Mullen, 1983), but plot close to the dividing line between thetholeiitic and caic-alkaline fields on a Si02 versus FeO*/MgO diagram (not shown; Miyashiro,1974). On the other hand, a ZrIY ratio of 2.5 to 3.1 for the Price andesite indicates a tholeiiticaffinity (Zr/Y = 3-5; MacLean and Barrett, 1993).Price andesite is classified as a basaltic andesite based on Figures 4. la and b. However, itscalc-alkaline or tholeiitic affinity is not clear. The eruptive morphology of the Price andesite isconsistent with it being tholeiitic rather than caic-alkaline as it consists mostly of poorlyvesiculated, moderately porphyritic (8-15% phenocrysts) flows. In contrast, calk-alkaline basalticandesites tend to have a higher portion of volcaniclastic rocks and are highly porphyritic]2.TABLE 4.1. GEOCHEMICAL ANALYSES OF LEAST-ALTERED ROCKS1FROM THE BATTLE ZONE2,BUTLE LAKE MINiNG CAMP.Price Price Price Price Price Price Chert Pumiceous Rhyoliticandesite2 andesite2 andesite2 andesite2 andesite2 andesite2 lapilli tuff tuff. seds.Sample# 229WR P122D D2108 D2114 D2214 P1326 11W 33W 18WSection 1585 1585 1585Drillhole W190 14-909 14-907 14-910Depth (Il) 2704 876 834 929Depth (m) 824.4 0.0 0.0 0.0 0.0 0.0 267.1 254.3 283.2Weight %Si02 52.9 53.4 57.7 52.7 54.1 53.7 92.20 59.80 74.70Ti02 0.83 0.81 0.72 0.85 0.71 0.91 0.13 0.51 0.26A1203 18.44 16.3 15.8 17.8 15.6 18.1 2.85 19.80 14.10Fe203 9.55 10 9.15 9.94 10.3 11.5 1.56 4.97 2.34MnO 0.14 0.16 0.16 0.18 0.21 0.11 0.02 0.03 0.02MgO 4.21 5.85 4.91 5.56 8.1 6.19 0.14 0.84 0.55CaO 5.55 9.69 7.16 7.09 6.99 4.69 0.19 0.26 0.06Na20 4.12 3.17 4.08 5.56 3.63 4.27 0.04 0.42 0.34K20 0.49 0.16 0.08 0.16 0.23 0.26 0.74 5.38 3.61P205 0.26 0.34 0.24 0.3 0.21 0.32 0.02 0.13 0.03LOl 4 1.15 5.10 2.95Sum 100.49 99.88 100 100.14 100.08 100.05 99.039 97.243 98.961ppmCr 26.2 90 19 20 323 21 61.3Ni 22Co 19.3 2.6V 186Cu 73 69 61 46 64 98 192 373 16Pb 5.4 39 5 329Zn 89 2110 3800 445Ga 17.2S 25900 17400 25As 3 3Sc 25.8 5.5Sb 0.5 0.6Au 3 57Ba 434 1070 4420 4090Rb 7.2 25 79 53Sr 407.7 417 642 480 212 370 5 17 32Nb 8.1 6 11 9Zr 81.7 90 61 65 58 71 40 160 128y 32.6 29 24 24 21 25Th 0 1 7 4U 0.8 1.3Cs 0.6 0.6Hf 2.2 3.1La 13.9 14 4 10 8 4 7.9Cc 31 16 19 16 12 32 15Nd 17 16 11 14 13 14 7Sm 4.22 4.7 5.6 6.4 4.4 5.2 1.27Eu 1.34 1.1 1.4 1.3 1.2 1.2 0.21Th 0.8 0.2TABLE 4.1. GEOCHEMICAL ANALYSES...TRACE ELEMENTS.. .CONTINIJEDPrice Price Price Price Price Price Chert Pumiceous Rhyoliticandesite2 andesite2 andesite2 andesite2 andesite2 andesite2 lapilli tuff tuff. sedsSample# 229WR P122D D2108 D2114 D2214 P1326 11W 33W 18WYb 2.58 2.3 2 18 1.6 2 0.66Lu 0.37 0.11Z.r/Y 3.1 2.5 2.7 2.8 2.8Quartz >1% 10% >1%Feldspar rare trAccessory3 AP,MT AP,MT AP,MT AP,MT AP,MTAjteration3 CL EP C1 EP CL, EP CL, EP CL, EP QZ, SE, SE QZ,PY SE,CA1. Units are descibed in Figure 3.1 and section 4.1.2. Samples are from outside the Battle zone (Juras,1987). Locations for remaining samples are in Chapter 5.3. Mineral codes are: AC = actinolite, AP = apatite, CA = calcite, CL = chlorite, CP = clinopyroxene, EP = epidote, HBhomblende, MT = magnetite, PY = pyrite, QZ = quartz,and SE = sericiteTABLE 4.1. GEOCHEMICAL ANALYSES OF LEAST-ALTERED ROCKS1FROM THE BATTLE ZONE2,BUTTLE LAKE MINING CAMP...CONTINUED.Unit QP QFP QFP2 QFP4 QFP4 GQFP QFPD HangingwallandesiteSample# 79W 81W D1362 D39903 P118G 62W 227WR 13OWRSection 1585 1585 1585 1372 1798Drillhole 14-900 14-911 14-904 14-753 14-917Depth(ft) 927 935 617 668 803Depth(m) 282.6 285.1 0.0 0.0 0.0 188.1 203.7 244.8Weight %Si02 78.20 78.70 71.7 81.5 78 81.10 64.38 51.86T02 0.20 0.20 0.23 0.12 0.17 0.18 0.26 0.73A1203 10.80 10.90 14.1 9.95 12.8 8.98 16.59 17.68Fe203 0.75 0.70 2.48 1.32 1.18 1.33 3.49 9.33MnO 0.06 0.06 0.04 0.02 0.03 0.04 0.13 0.14MgO 0.42 0.38 0.66 0.31 0.44 0.70 1.32 5.04CaO 1.81 1.82 2.9 1.65 1.27 1.86 3.1 5.59Na20 5.00 5.14 5.96 4.22 4.71 3.82 3.24 4.11K20 0.75 0.75 1.9 0.84 1.39 0.53 2.58 0.41P205 0.05 0.05 0.09 0.04 0.05 0.04 0.15 0.21LOl 0.65 0.55 0.45 4.42 5.15Sum 98.689 99.253 100.06 99.97 100.04 99.029 99.66 100.25ppmCr 160 69.7Ni 0 18Co 2.7 4.7V 36 196cii 28 1 18 34 1 34 112Pb 13 4 1 2.6 8.2Zn 37 30 66 54 95 196Ga 14.7 15.6S 58500 5000 118000As 5 1Sc 4.5 4.6TABLE 4.1. GEOCHEMICAL ANALYSES...TRACE ELEMENTS. ..CONTINUEDUnit QP QFP QFP2 QFP QFP2 GQFP QFPD HangingwallandesiteSample# 79W 81W D1362 D39903 P1180 62W 227WR I3OWRSb 0.5 0.2Au 1 1661 684 519 354Rb 19 21 43 14 19 33 46.6 4.2Sr 146 155 350 190 279 115 175.6 302.5Nb 6 8 3 2 9 11.4 6.4Zr 81 116 135 90 103 103 75.5 57.4V 20 14 12 17.5 25.4Th 1 4 7 0 9.9U 1.2 1.5Cs 0.1 0.9Hf 2.6 1.8La 13.5 26 15 5 16.2Ce 27 21 24 20 31Nd 13 11 8 8 13Sm 2.41 2.8 3.7 5.4 2.37Eu 0.63 0.62 0.92 1.0 0.7Th 0.6 0.4Yb 2.81 1.4 1.8 1.3 1.63Lu 0.43 0.25Zr/V 9.8 6.75 6.4 8.6 4.3 3.1Quartz 2% 2% 5% 8% 1%Feldspar tr 6% 12% 35% 25%Accessory3 AP MT MT,HB MTAlteration3 SE, QZ,SE,PY QZ,SE,CA,CL CA,CL,SE CA,EP,CLQZ,PY1. Units are descibed in Figure 3.1 and section 4.1.2. Samples are from outside the Battle zone (Juras, 1987). Locations for remaining samples are in Chapter 5.3. Mineral codes are: AC = actinolite, AP = apatite, CA = calcite, CL = chlorite, CP = clinopyroxene, EP = epidote, NBhomblende, MT = magnetite, PY = pyrite, QZ = quartz,and SE = sericiteFigure 4.1 Geochemical discrimination diagrams for least altered rocks from the Price formation(squares), hangingwall andesite (half filled square) and rhyolite flows (circles) in H-W horizon.Data are from Table 4.2 and Juras (1987). (a) Silica versus Zr/Ti02digram after Winchester andFloyd (1977). Price formation samples plot in the andesite field whereas data from the rhyoliteflows are smeared vertically throughout the rhyolite and rhyodacite/dacite fields. Scatter alongthe silica axis could be due to mobility of Si or other elements such as Na, Ca, K, Fe or Mg. (b)Cation % plot after Jensen (1976). CR = calc-alkaline rhyolite. CD = calc-alkaline dacite. CA =calc-alkaline basalt. TR = tholeiitic rhyolite. TD = tholeiitic dacite. TA = tholeiitic andesite.HMT = high Mg tholeiite. HFT = high-Fe tholeiite. BK = basaltic komatiite. PK peridotitickomatiite. Most rhyolites plot in the caic-alkaline rhyolite field. Most samples from the Priceformation plot in the calc-alkaline basalt field.80757060‘;5 55504540I IA PhyoIitCorn/PanPhonolite/A,/Sub-AB /Bas/Trach/NephI 11111111 I I 1111111 I III.01.001Zr /‘?i02FeO* + Ti02B10A1203 MgO77Figure 4.1. Variation diagrams showing least altered rocks. . .continued. C. Data from the Priceandesite plotted on a Zr/Y versus Zr discrimination diagram after Pearce and Norry (1979). Dataplot in overlapping field between mid-ocean ridge basalts and island-arc basalts.20 • • . •A: Within plate basaltsB: Island arc bcisalts10 C: Mid-ocean ridge basaltsABC1I I I I I III10 100 1000Zr (ppm)7’porphyritic compared to the tholeiitic series (Wilson, 1988). The phenocryst assemblage in thePrice andesite consists of clinopyroxene and plagioclase with magnetite as an important accessorymineral. This assemblage may be found in either tholeiitic or caic-alkaline rocks and is notdiagnostic of either series (Wilson, 1988).4.3.2 Felsic RocksRhyolite samples from the flow-dome complex (Table 4.1) plot in the rhyolite fields onFigures 4.1 a and b. Scatter in Figure 4.1 a is parallel to the silica axis because of element mobility(section 5.4.2); the Zr/Ti02ratio is constant. Most of the rocks plot in the caic-alkaline rhyolitefield on Figure 4.2b. They also have a Zr/Y ratio between 5.9 and 9.1 (Table 4.1) which is typicalof caic-alkaline rocks (MacLean and Barrett, 1993).4.4 ROCK-FORMiNG PROCESSESVariations in chemical analyses of non-fragmental volcanic rocks are generally due to: (i) rockforming processes including fractionation, magma mixing and assimilation, (ii) closure, amathematical constraint that requires the sum of all element concentrations in a rock to equalunity, (iii) hydrothermal metasomatism, and (iv) other processes such as sea water metasomatism,later metamorphism and weathering (Stanley and Madeisky, 1994). If magma mixing andassimilation are not important rock forming processes, or are limited to the source region suchthat magmas are essentially homogeneous prior to fractionation, the effect of closure may beremoved mathematically using element ratios. Igneous fractionation and hydrothermalmetasomatism can then be modeled quantitatively using Pearce element ratios. In this section,rock-forming processes in the Battle zone are investigated. Chapter 5 considers the effects ofhydrothermal metasomatism. Other processes are considered to be less important contributors toobserved lithogeochemical variations.Pearce element ratios (PERs) of geochemical data can be used to discriminate betweendifferent rock forming processes (Russell and Nicholls, 1988). Rocks that are related by igneousfractionation from a homogeneous parent magma are comagmatic and can have one or moreelements that were not involved in the fractionation process. These incompatible elementsremain in the melt. If they are also immobile during post depositional alteration, they areconserved, and may be used as monitors of material transfer processes in rocks. Specifically,conserved element ratios are constant in a suite of fractionated rocks derived from ahomogeneous parent (Stanley and Madeisky, 1993). If no conserved elements are present one ofthe following must be true (Russell and Nicholls, 1988): (i) all the elements must be fractionating(or mobile during metasomatism), (ii) diffi.ision must be causing chemical variation, (iii) thesystem is open, or (iv) the rocks are not related.To test if the rocks are comagmatic either a scatterplot of concentration data, or a PERconserved element diagram may be used. On a scatterplot, pairs of oxide or trace elementconcentrations will form a linear trend through the origin if those elements are conserved (Pearceand Norry, 1979). On a PER conserved element diagram, pairs of Pearce element ratios areplotted against each other (Russell and Nicholls, 1988). If all the data from a suite of rocks plotas a point within analytical error, all the elements on the diagram are conserved. In either case,the possibility exists that the rocks are comagmatic. In addition, rock-forming processes otherthan fractionation generally can be eliminated as important contributors to chemical variation.Data from Table 4.1 for least altered rocks in the Price formation and rhyolite units in H-Whorizon are plotted on the Ti02 versus Zr scatterplot ofFigure 4.2a. Data from the rhyolite flow-dome complex form a tight linear trend through the origin, indicating that both Ti and Zr areincompatible elements. This trend, however, is not entirely a result of igneous fractionation.Mass loss due to sericitization has residually elevated the Ti02 and Zr contents in most of thesamples (section 5.2). The rhyolite dike identified in Section 1 3+72E (Figure 3.2) plots awayfrom the main rhyolite trend, indicating that it is not related to the rhyolite flow-dome complex.Figure 4.2. Conserved element scatterplots for the Price andesite and H-W horizon rhyolite,Buttle lake mining camp, southwestern British Columbia. Data are from Table 4.1. (a) Ti02versus Zr. Within error, data from the rhyolite flow dome complex forms a linear trend throughthe origin. Data from the Price andesite are scattered, apparently reflecting fractionation of T102into Fe-Ti oxides. (b) Y versus Zr yields a linear trend for the Price formation, suggesting thatneither Zr nor Y are involved in fractionation. Not enough Y analyses are available toconclusively draw a trend for the rhyolite data. Note that in both diagrams the rhyolite dike(QFPD) plots by itself, therefore it is not related to the rhyolite flow dome complex.8ZScc>-AnalyticalerrorC\10,1/ Analytical Price andesiteerror9Rhyolite dike(QFPD) 0 —I-Rhyolite flows‘I0 50 100 150Zr (ppm)1.00.80,60.40.20.04030201000 50 100 150Zr (ppm)A Zr versus Y linear trend, suggesting the elements Zr and Y are not involved in fractionation ofthe andesite. Consequently, for the remainder of this discussion, Zr is used as the conservedelement in both rock suites. Zr has the added advantage that it is well measured in all the batchesof geochemical data and it is generally immobile during metasomatism (MacLean and Kranidoitis1987; MacLean, 1990; Pearce and Norry, 1979).Once a conserved element is identified, the masking effect of closure may be removedmathematically so that variations due to process may be identified and interpreted. Pearce (1968)introduced a type of variation diagram that removes the effect of closure by describing rockcompositions in terms of molar ratios with a conserved element in the denominator. In this way,petrologic controls on geochemical variations may be investigated.Pearce element ratios are calculated as follows (Russell and Nicholls, 1988): all weight %oxide analyses are converted to element fractions, e1, by:e1 = W1A/MW,where W1, A’ and MW are weight percentages, the number of cations in the oxide formula and themolecular weight of oxide i respectively. The Pearce element ratio (PER1)of element e1 is:PER1= e1 ewhere e is a conserved element.Linear combinations of PERs may be plotted on a diagram to test specific petrologichypotheses about a suite of comagmatic rocks. For example, chemical variations in a basaltic lavacould be the result of olivine sorting. To test this hypothesis, a diagram with abscissa0.5(Fe+Mg)/Z and ordinate SIIZ where Z is a conserved element, may be constructed. If olivinesorting (either forsterite orfayalite) is responsible for the chemical variation, the data will define aline with a slope of 1. A matrix equation developed by Stanley and Russell (1989) can be used todesign the appropriate axes numerators for PER diagrams to test more complex fractionationscenarios. A generalized approach to modeling basaltic rocks is presented in Russell and Nicholls(1988) and Russell and Stanley (1990). Fractionation (and hydrothermal alteration) in felsic rocks8qalteration) in felsic rocks was investigated using Pearce element ratios by Madeisksy and Stanley(1993) and Stanley and Madeisky (1993). PER analysis ofPrice andesite and units of the rhyoliteflow-dome complex follow.4.4.1 PER analysis of Price andesiteThe Price andesite consists of alternating feldspar ± pyroxene porphyritic and pyroxene +feldspar porphyritic mafic to intermediate flows (Juras, 1987). Feldspar and clinopyroxene are themain phenocryst phases; apatite and magnetite/ilmenite are important accessory phases (section2.1 and 3.2.1). One possibility is that sorting of feldspar and clinopyroxene alone is responsiblefor the geochemical variation in the Price andesite (case 1). On the other hand, fractionation ofclinopyroxene, feldspar and olivine (case 2) may have occurred. Although olivine phenocrysts arenot observed in the Price andesite, sorting of olivine may have occurred in the magma chamber.A third possibility (case 3; Juras, 1987) is that chemical variations in the Price andesite could beexplained by fractionation of Fe-Ti oxides as well as feldspar, clinopyroxene and olivine.Three PER diagrams (Figures 4.3 a to c) were constructed to test the rival hypothesesoutlined above. The numerator axes coefficients are summarized in Table 4.2. The coefficientsare calculated such that all the data will lie along a line of slope 1 (within analytical error) if theaxes adequately describe the stoichiometry of the rock-forming system. Axes coefficients for case1 and 2 are available from Russell and Nicholls (1988) and Russell and Stanley (1990),respectively. The third set of axes coefficients defines a Q diagram (Nicholls and Russell, 1991)designed to test for sorting ofFe2TiO4as well as olivine, augite and plagioclase. Because thecomposition of Fe-Ti oxides in the Price andesite is not known, this diagram can onlyapproximately model sorting of those minerals; the other Fe-Ti oxide components (Fe203,FeTiO3,and Fe3O4)would cause small deviations from the model slope of one.Sorting of feldspar and clinopyroxene (case 1) clearly does not explain all the chemicalvariation in the Price andesite. Most of the data in Figure 4.3a plot along a line of slope 0.7,suggesting that addition or loss of olivine also occurred (cj Russell and Nicholls, 1988).Including olivine in the model (case 2) is better; four of six data points on Figure 4.3b plot along aline of slope 1. The effect of magnetite, however, is to move some of the data points away fromthe fractionation trend parallel to the ordinate. Clearly, fractionation of magnetite is significant inthe Price andesite as shown on the Q plot of Figure 4.6c.Another way to test the importance of magnetite and olivine fractionation is by constructinga diagram with axes [3A1-4Ca+6(Fe+Mg)]/Zr versus Si/Zr (C. Stanley, personal communication,1994; Figure 4.3d). This type of diagram is aphase discrimination diagram (Russell andNicholls, 1988). If all the variation in the rocks were due to sorting of feldspar andclinopyroxene, the data would plot along a line of slope 1 in Figure 4.3d. On the other hand, ifonly olivine or magnetite sorting had occurred, all the data would plot along either a line of slope12 or infinity, respectively. Because the data all plot between the various phase vectors on Figure4.3d, neither clinopyroxene, feldspar, olivine nor magnetite can be eliminated as contributors tothe chemical variation in the Price andesite. In conclusion, data in Table 4.3 and Figure 4.3 areconsistent with the hypothesis: lavas in the Price andesite are comagmatic and are related bysorting offeldspar, pyroxene, olivine and Fe-Ti oxides.TABLE 4.2. SUMMARY OF PEARCE ELEMENT RATIOS USED N TESTING PETROLOGICHYPOTHESES FOR THE PRICE ANDESITE, BUTI’LE LAKE MINiNG CAMP.Case Phases’ X axis Y axis Reference1 PL+PX Si 2Ca-I-3Na Russell andNicholls (1988)2 PL+PX+OL Si O.25Al+O.5Fe+O.5Mg+1.5Ca+2.75Na Russell andStanley (1990)3 PL+PX+OL+Fe2Ti4 Si+Ti+Fe+Na 1.36(Si+Ti)-0.O9Al+0.82Fe-0. l8Mg-0.55Ca Nicholls andRussell (1991)1PL = plagioclase, PX = augite, OL = olivineFigure 4.3. Pearce element ratio diagrams designed to test rival hypotheses summarized in Table4.2. (a) Diagram to test for sorting of plagioclase feldspar and clinopyroxene. Most of the dataplot along a line of slope < 1 indicating that addition or loss of olivine has also occurred (efRussell and Nicholls, 1988). (b) Plagioclase feldspar, augite and olivine assemblage test diagram.Most data plot along the model line of slope 1. The effect of magnetite fractionation, however,moves some of the data points away from the fractionation trend parallel to the ordinate.1.8a: Least altered1.6 Price andesite m=1plagioclase and pyroxene _/1 4 fractionation _/E1.2LI.IAnalyticalZ 0.8 Analytica errorerroro 0.60.4 Aslopeoflessthanonesuggests divine0.2is fractionathig0 I I I0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2Si/Zr PER (molar)2cc 1.8b: Least altered1.6 Priceandesitec,i 1.4’1.2 I-+Magnetite — AnalyticalW 1 errorUo 0.8 Analytical+ error 4- —m=1to 0.6 feldspar, pyroxene andolivine fractionation0.4.,_: 0.2I I I I0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2Si/Zr PER (molar)Figure 4.3 continued... (c) Q plot. Diagram (cf Nicholls and Russell, 1991) is designed to test forsorting of plagioclase, clinopyroxene (augite), olivine and Fe2TiO4in the Price andesite. Withinanalytical error, all the data fit a model line of slope 1, indicating that an oxide composition ofFe2TiO4is a reasonable approximation for the Price andesite. (d) Phase discrimination diagramfor olivine, magnetite, feldspar and clinopyroxene. All the data plot between the phase vectors,therefore all of the phases must be contributing to the geochemical variation. Scatter in the dataindicates that olivine, magnetite, feldspar and clinopyroxene were not sorted in consistentproportions.1.8 I C: Least altered - IPrice andesite1.6 Analyticalerror1.4m=1feldspar, pyroxene, olivineo 1.2 dFe-Ti oxide fractionation—I-Ct 1w Analyticalerror0.80.60.40.200 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2Si+1i÷Fe+Na/Zr PER (molar)Q=[1.36(Si+Ti)-O.09A1÷.82Fe-O.l8Mg-O.55Ca]4.5 altered-ö AnalyficalE error3.5 Feldspar andW dilnopyroxene— Ifractionation 7‘- 32.5 —+ Magnetite- fractionation(01.5 Analytical Olivineo error fractionation‘4-; i•0.5•I I I I I I0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2SVZr PER (molar)tb4.4.2 PER analysis of the rhyolite flow-dome complexRhyolite units within the flow-dome complex (QP, QFP, and GQFP; section 3,2.2.7)progressively increase in feldspar, quartz and ‘mafic’ mineral content and become more coarselycrystalline from stratigraphic base to top. This implies episodic emplacement from a crystallizingsource magma chamber (i.e. the flows are comagmatic). Petrographic evidence suggests thecrystallization sequence quartz => feldspar => mafics + magnetite, although the timing ofquartz relative to feldspar is not certain. The occurrence of mafic minerals as the latestcrystallizing phase rather than as early phenocrysts requires some explanation. It could be thatcrystallization of the mafic component was controlled by the concentration of iron and magnesiumin the residual melt, not by temperature, as is the case in mafic melts. In any case, sorting of maficsilicates and oxides does not appear to be important in the H-W horizon rhyolite.Conserved elements Ti and Zr (Figure 4.2a) support the interpretation that the rhyoliteflows within the Battle zone are comagmatic. The coincidence of data for felsic units analyzed byJuras (1987; Table 4.1) with those from the Battle zone apparently confirms that rhyolite flows inthe same stratigraphic position elsewhere on the property are from the same magma chamber, andindeed part of the same fissure eruptive system. Varying proportions of feldspar and quartz inindividual flow units suggests primary igneous chemical variations are probably due to sorting ofalkali feldspar, anorthite and quartz. Fractionation of feldspar can be modeled on a Pearceelement ratio (PER) assemblage test diagram with Al/Zr PER on the abscissa and (2Ca+Na+K)/ZrPER on the ordinate (Figure 4.4a). This diagram is insensitive to quartz fractionation becauseboth the numerator and denominator would all be enriched or diluted proportionally by loss oraddition of quartz.Loss of feldspar from the system causes the most evolved samples to plot toward the originin Figure 4.4a. This is an effect of the amount of Zr left in the system and the loss ofNa, K andAl. If accumulation of feldspar were responsible for the variations in Na, K and Al, the mostgevolved samples would plot away from the origin. The effect of quartz fractionation is bestshown on an Si/Zr PER versus Al/Zr PER plot (Figure 4.4b). The data are bounded by vectorsshowing the effect of quartz and feldspar fractionation separately. As above, least evolvedsamples plot away from the origin, implying that loss of quartz from the system is responsible forvariations in Si02.Figure 4.4. PER assemblage test diagrams for least altered samples of rhyolite flows from theBattle zone and elsewhere in the Buttle Lake mining camp, southwestern British Columbia. (a)(2Ca+Na+K)/Zr PER versus Al/Zr PER (cf Stanley and Madeisky, 1994) models alkali feldsparfractionation. QP = quartz porphyritic rhyolite (least evolved), QFP = quartz feldsparporphyritic rhyolite, GQFP = green quartz feldspar porphyritic rhyolite (most evolved). (b)Al/Zr PER versus Si/Zr PER plot for all rhyolite data from the Battle zone and elsewhere in theButtle Lake mining camp. Rhyolite flow analyses plot within the area bounded by quartz andfeldspar fractionation vectors.0.3_____________________QA: Least altered rhyolite_____0.25QFP Analytical— QFP errorcrW ‘-‘ Analytical QFPerror +GQFP0.15z0m=1Feldspar fractionation0.050 p0 0.05 0.1 0.15 0.2 0.25 0.3Al/Zr PER0.40.35 B: Least altered rhyolite0.3Quartz fractionationAn90.2ft. QFP )‘GQFP0.15 i- J Feldsparp fractionation0.10.050 I I0 0.5 1 1.5 2 2.5Si/Zr PER (molar)gqCHAPTER 5ALTERATION5.1 INTRODUCTIONAlteration in the Battle zone extends both into the footwall and the hangingwall. Footwallalteration is stratabound within the Price andesite and consists of a quartz-sericite ± chiorite-pyriteassemblage similar to alteration zones below many Australian deposits (Large, 1992).Hangingwall alteration is restricted to the H-W horizon rhyolite and does not extend into theoverlying hangingwall andesite. The alteration assemblage is dominantly sericite with lesserpyrite, quartz and chlorite.This chapter characterizes the mineralogy and geochemistry of footwall and hangingwallalteration in the Battle zone using data from Section 15+85E (Figure 3.5) and Section 17+98E(Figure 3.4). All of the lithogeochemical data from the lithologic units defined in Chapter 3 arereported in Tables 5.1 to 5.6. Analytical details are in Chapter 4 and Appendix A. All the wholerock samples were also examined by thin section. Selected samples were analyzed by microprobeand X-ray diffraction to confirm the patterns observed in the lithogeochemical data plots.Element behaviour in the altered rocks was assessed following the graphical method ofGrant (1986). If two or more components are immobile during metasomatism, then their weightratios remain constant, despite possible changes in their absolute abundances. On a cross-plot ofconcentration data, immobile elements plot on a line through the origin. Behaviour of the rareearth elements was also evaluated for selected samples.Gain or loss of elements due to metasomatism were evaluated using the approach describedin Stanley and Madeisky (1994). The fundamental relationship quantifying the amount of materialtransfer, Ti is described in the equation:Ti=Xi1,(xjd/xfd - xjJ,/xfl,) (A)where is the amount of conserved elementj in a rock and Xid/Xjd andx1,ixj are Pearceelement ratios (PERs; section 4.4) of element i in the daughter and the parent, respectively.Because X, is conserved, it is an unknown constant. Therefore, any difference in the ratio isproportional to the amount of transfer of element i. Because of this proportionality, it is notnecessary to assume a parent composition.Material transfer in the Battle zone is primarily achieved by igneous fractionation ormetasomatism. In Chapter 4 the elements involved in fractionation of both the Price andesite andthe H-W horizon rhyolite were identified using Pearce element ratio assemblage test diagrams andphase discrimination diagrams. The same type of diagrams can also be used to model andquantif,r metasomatism (Stanley and Madeisky, 1993). Samples that do not conform to thefractionation model have undergone metasomatic material transfer. The amount of transfer isquantified by calculating residuals from the fractionation model to the least alteredlithogeochemical data points.cTABLE 5.1 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THEPRICE ANDESITE, BATTLE ZONE, BUTLE LAKE MINING CAMP, SOUTHWESTERN BRITISHCOLUMBIA.Unit Price1 Price1 Price1 Price’ Price1 Price Price Price Price PriceSample P122D D2108 D2114 D2214 P1326 229WR 164WR 08W 07W 169WRLab Code 94-099 BARR1 BARR164 69Section 1798 1585 1585 1798Drillhole W190 14-914 14-908 14-908 14-914Depth(ft) 2704 825 976 945 945Depth(m) 0.0 0.0 0.0 0.0 0.0 824.4 251.5 297.6 288.1 288.1Weight %Si02 53.4 57.7 52.7 54.1 53.7 52.9 59.26 71.80 41.20 56.67Ti02 0.81 0.72 0.85 0.71 0.91 0.83 0.74 0.64 0.46 0.68203 16.3 15.8 17.8 15.6 18.1 18.44 16.73 14.50 8.74 17.11Fe203 10 9.15 9.94 10.3 11.5 9.55 9.19 2.51 30.70 8.18MnO 0.16 0.16 0.18 0.21 0.11 0.14 0.12 0.02 0.01 0.19MgO 5.85 4.91 5.56 8.1 6.19 4.21 4.63 0.50 0.29 5.05CaO 9.69 7.16 7.09 6.99 4.69 5.55 0.33 0.16 0.08 0.71Na20 3.17 4.08 5.56 3.63 4.27 4.12 0.00 0.17 0.11 0.46K20 0.16 0.08 0.16 0.23 0.26 0.49 3.33 4.00 2.55 3.540.34 0.24 0.3 0.21 0.32 0.26 0.19 0.06 0.05 0.20LOT 4 6.10 3.20 16.50 6.86Sum 99.88 100 100.14 100.08 100.05 100.49 100.62 97.562 100.687 99.65ppmCr203 47 268 113Ni 22 27 23Co - 27 21 30V 186 192 136Cu 69 61 46 64 98 73 360 92 886 240Pb 5.4 7.3 3 1 37.6Zn 89 306 87 1550 8855Ga 17.2 16.8 22.4S 7620 119000Sc 22 20 11Ba 434 2098 1980 798 178Rb 7.2 41.3 66 35 43.4Sr 417 642 480 212 370 407.7 18.3 24 5 28.3Nb 8.1 8.1 8 4 8.5Zr 90 61 65 58 71 81.7 57.4 63 39 82Y 29 24 24 21 25 32.6 22.7 30Th 0 10.5 1 1 10.5U 1.3 4.8 6.9Ce 29 29 -- 361 Data are from Juras (1987).TABLE 5.1 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THEPRICE ANDESITE, CONTINUED....Unit Price Price Price Price Price Price Price Price PriceSample 167WR 12W 50W 15W 157WR 13W 14W 06W 184WRLab Code BARR167 BARRL57 BARR184Section 1798 1585 1585 1585 1798 1585 1585 1585 1798Drillhole 14-9 14 14-909 14-906 14-909 14-9 15 14-909 14-909 14-908 14-9 13Depth(ft) 900 946 1017 996 934 965 965 908 830Depth (m) 274.4 288.4 309.9 303.7 284.8 294.2 294.2 276.8 253.0Weight %Si02 56.82 65.10 62.80 64.10 32.18 26.90 30.40 41.40 67.89Ti02 0.85 0.54 0.69 0.47 1.09 0.91 0.94 0.36 0.54203 20.68 11.90 16.90 11.10 20.75 18.40 18.90 6.59 12.28Fe203 7.56 9.56 7.03 11.60 21.43 29.90 27.00 32.70 9.03MnO 0.03 0.01 0.03 0.02 0.12 0.01 0.01 0.01 0.00MgO 1.18 0.37 0.73 0.50 1.44 0.56 0.58 0.22 0.46CaO 0.52 0.15 0.33 0.24 2.06 0.24 0.36 0.03 0.19Na20 0.01 0.25 0.14 0.11 0.09 0.23 0.24 0.04 0.14K20 5.74 3.19 4.75 3.10 5.47 5.47 5.53 1.87 3.460.28 0.07 0.19 0.22 0.33 0.21 0.25 0.02 0.13LOl 6.33 6.25 5.60 7.20 13.70 17.30 16.10 16.80 5.83Sum 100 97.386 99.19 98.657 98.66 100.131 100.306 100.042 99.95ppmCr203 340 305 421Ni 19 29 28Co 25 40 25V 146 228 146Cu 249 4020 421 736 4333 432 709 5020 2050Pb 15.9 3 20 6 69.3 18 11 1 9.8Zn 103 4540 62 300 456 106 66 746 229Ga 19.9 21.6 14.2S 43300 25900 46200 131000 118000 152000Sc 19 22 15Ba 2383 1340 2190 1350 2431 1890 1910 596 1731Rb 72.6 49 71 50 70.6 71 83 40 44.1Sr 34 5 16 16 58.3 22 20 5 24.1Nb 9.4 7 7 6 9 6 8 3 7.5Zr 97.6 63 67 49 117.9 64 67 35 46.8Y 32.6 28.4 16.5Th 14.2 1 1 7 11.9 1 14 5 12.7U 6 14.6 6.6Ce 65 51 33Cr203NiCoVCuPbZnGaSScBaRbSrNbZrYThUCe6 261492 115554.6 45.235.8 111.38.2 8.981 40.821.5 14.83 11 05.1 030 213681397214521916512611953622.18.470.42312.86.729TABLE 5.1 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THEPRICE ANDESITE, CONTINUED....Unit Price Price Price Price Price Price Price Price PriceSample 185WR 187WR 186WR 178WR 173WR 51W 174WR 176WR 175WR* *Lab Code BARRL85 BARR187 BARRI86 BARRI78 BARR173 BARR174 BARR176 13ARR175Section 1798 1798 1798 1798 1798 1585 1798 1798 1798Drillhole 14-913 14-913 14-913 14-920 14-920 14-906 14-920 14-920 14-920Depth(ft) 887 943 944 980 811 1044 880 915 881Depth (m) 270.4 287.5 287.8 298.8 247.3 318.3 268.3 279.0 268.6Weight %Si02Ti02A1203Fe203MnOMgOCaONa20K20LOlSumppm59.300.7316.008.370.123.140.260.133.890.196.0098. 12652.700.6115.988.610.807.401.210.562.940.187.8498.8386264317254045.91214720.970.21 43.980.50 0.6812.81 15.547.02 9.790.02 0.650.57 6.610.35 6.270.12 0.193.59 3.220.14 0.225.03 12.02100.36 99.1753.120.6516.268.021.037.551.710.093.080.187.4699.1519538221561214394016.171.130.4210.228.680.020.450.370.002.870.185.6199.9561.750.6917.017.150.101.100.540.674.750.235.8399.821142512623819.86376211393060.831.38.683.225.811.57.25149.61 64.290.74 0.7219.28 15.849.99 7.810.32 0.016.63 0.500.64 0.410.19 0.084.22 4.380.21 0.148.09 5.7899.92 99.96226 47850 2033 14198 159145 43013.9 17253 3519.1 16.617 121590 212554.7 54.646.1 35.810.1 8.271.7 6216.3 21.50 110 5.141 32332 14720 3418 4082 209346 230 1074 13.1 3.7160 148 49216.6 15.3238001820551555317 19118535.9 39.832.9 34.97.1 8.165.1 68.124.9 2111.8 8.58.6 5.542 46TABLE 5.1 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THEPRICE ANDESITE, CONTINUED....qc1Unit Price Price Price Price Price Price Price Price PriceSample 59W 58W 28W 38W 36W 119WR 1O8WR 23W 83WLab Code BARR1 BARR119 08Section 1585 1585 1585 1585 1585 1798 1798 1585 1585Driiihole 14-905 14-905 14-912 14-907 14-907 14-919 14-918 14-910 14-906Depth(ft) 1055 1008 1085 950 908 1015 1030 1095 1062Depth(m) 321.6 307.3 330.8 289.6 276.7 309.5 314.0 333.7 323.8%WeightSi02 53.20 46.80 30.00 39.10 30.80 54.35 34.62 32.80 60.60TiO2 0.74 1.22 1.04 1.18 0.76 0.89 0.33 0.96 0.70203 16.30 27.50 22.40 25.40 14.20 21.62 8.20 23.00 15.90Fe203 12.40 6.32 20.50 10.60 31.80 7.55 35.20 20.20 7.82MnO 0.20 0.03 0.13 0.24 0.01 0.10 0.02 0.03 0.09MgO 3.16 1.30 5.91 6.27 0.46 2.99 0.32 1.47 2.61CaO 0.84 1.05 0.39 0.68 0.08 0.28 0.14 0.33 0.34Na2O 0.12 0.34 0.20 0.18 0.13 0.14 0.00 0.29 0.10K20 3.85 7.42 5.18 6.07 4.18 5.59 2.31 6.29 4.04P205 0.21 0.78 0.24 0.31 0.07 0.19 0.08 0.26 0.22LOI 7.60 6.30 13.60 8.90 17.70 6.37 19.06 13.30 5.85Sum 98.62 99.06 99.59 98.93 100.19 100.07 100.281 98.929 98.265ppmCr2O3 242 300Ni 41 21Co 29 29V 189 81Cu 752 973 34 804 442 238 627 234 517Pb 4 4 7 6 11 19.2 42.1 3 6Zn 233 67 144 167 126 154 119 70 186Ga 20.3 12.65 32100 17400 75300 27400 134000 86900 24300Sc 18 4Ba 1660 2510 1840 2210 1120 1942 719 2090 1740Rb 47 88 74 95 57 67.8 20.5 62 69Sr 20 55 34 37 11 29.8 19.4 22 5Nb 4 9 5 8 5 8.8 7.8 7 9Zr 54 106 73 101 64 83.6 45.9 87 73Y 22.9 11.8Th 1 1 9 3 7 10.5 29.8 12 3U 4.6 15.8Ce 45 30100TABLE 5.1 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THEPRICE ANDESITE, CONTiNUED....Unit Price Price Price Price Price Price Price Price PriceSample 27W 82W 11OWR 145WR 143WR 147WR 149WR 148WR 48WLabCode BARR11O BARR145 BARRI43 BARR147 BARR149 BARRL48Section 1585 1585 1798 1798 1798 1798 1798 1798 1585Drillhole 14-912 14-906 14-918 14-916 14-916 14-916 14-916 14-916 14-906Depth(ft) 1042 1025 1085 1123 1003 1145 1196 1158 940Depth (m) 317.7 312.5 330.8 342.4 305.8 349.1 364.6 353.0 286.6Weight %Si02 33.00 57.40 50.16 44.29 56.19 64.16 68.10 57.23 30.90Ti02 1.17 0.73 0.88 0.92 1.02 0.53 0.73 0.61 0.41203 24.80 16.20 18.55 19.59 24.44 14.31 16.28 13.73 8.78Fe203 20.10 10.10 7.42 16.07 4.50 8.18 3.84 12.97 36.70MnO 0.01 0.11 0.40 0.07 0.00 0.13 0.13 0.12 0.01MgO 0.43 2.75 7.89 3.04 0.91 2.88 1.86 4.65 0.28CaO 0.07 0.32 1.77 0.74 0.30 0.47 0.53 0.42 0.23Na2O 0.35 0.11 0.09 0.09 0.11 0.00 0.00 0.00 0.06K2O 6.76 4.10 3.67 4.95 7.02 3.47 4.43 2.77 2.39P205 0.08 0.20 0.30 0.24 0.21 0.20 0.23 0.18 0.19LOI 13.10 6.85 7.88 10.49 5.23 5.85 3.97 7.83 19.60Sum 99.87 98.873 99.01 100.49 99.93 100.181 100.101 100.511 99.551ppmCr203 274 508 246 272 203 204Ni 54 40 9 10 14 18Co 33 39 8 14 16 35V 184 213 206 81 152 143Cu 122 286 168 124 74 206 70 74 1030Pb 20 8 26.8 35 6.1 7.1 11.7 8.7 19Zn 112 169 1602 78 25 85 79 100 179Ga 19 20.4 23.2 15.9 16.4 16.25 80800 27900 157000Sc 15 21 17 10 13 17Ba 2870 1810 1144 1612 2111 1187 1606 960 757Rb 85 70 46.8 61.3 88.6 44.6 54.9 36.2 50Sr 29 5 56.8 37.4 38.4 23.7 27.8 23.1 5Nb 6 4 8.3 8.5 10.3 8.4 9 7.7 7Zr 94 56 68.4 61.9 99.8 77.6 64.5 66.6 41Y 26.5 18 29.7 23.3 20,1 19.1Th 6 6 8.7 1.7 8.4 11.8 4.4 18.6 5U 4.3 3.2 2.8 5.2 0.4 9.7Ce 61 57 67 43 44 12TABLE 5.2 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THEPRICE ANDESITE AND CHERT WITHIN THE FINE RHYOLITIC TIJFFACEOUS DEPOSITS, BATTLEZONE, BU1TLE LAKE MINING CAMP, SOUTHWESTERN BRITISH COLUMBIA.Unit Price Price Price Price Chert Chert Chert Chert ChertSample 136WR 49W 60W 144WR 165WR 55W 47W 11W 77WLabCode BARRT36 BARR144 BARR165Section 1798 1585 1585 1585 1798 1585 1585 1585 1585Drillhole 14-917 14-906 14-905 14-900 14-914 14-905 14-906 14-909 14-900Depth(ft) 1126 970 1093 851 861 874 865 876 838Depth(m) 343.3 295.7 333.2 259.5 262.5 266.5 263.7 267.1 255.3Weight %Si02 43.71 46.30 52.80 69.50 96.62 89.50 89.00 92.20 83.30Ti02 1.66 0.66 0.84 0.23 0.07 0.14 0.11 0.13 0.09203 32.55 15.70 21.40 17.00 1.47 3.13 4.59 2.85 3.80Fe203 4.61 18.50 6.70 2.59 0.68 3.83 1.67 1.56 6.12MnO 0.01 0.12 0.15 0.03 0.00 0.01 0.02 0.02 0,02MgO 0.88 3.92 1.87 0.71 0.00 0.13 0.25 0.14 0.18CaO 0.23 0.28 1.10 0.40 0.31 0.01 0.24 0.19 0.13Na2O 0.27 0.13 0.23 0.30 0.00 0.01 0.01 0.04 0.04K20 9.30 3.42 5.76 4.40 0.40 0.81 1.18 0.74 0.99“205 0.17 0.19 0.29 0.03 0.22 0.02 0.08 0.02 0.02LOI 6.19 10.90 5.80 3.50 0.35 2.25 1.55 1.15 3.60Sum 99.58 100.122 96.938 98.691 100.12 99.839 98.7 99.039 98.288ppmCr2O3 446 325 439Ni 12 24 9Co 30 8 7V 322 124 35Cu 119 129 675 134 500 12 1 192 165Pb 10.4 10 6 2.4 3 13 4 39 20Zn 12 231 107 28 25 123 24 2110 125Ga 27.9 7.1S 66800 19200 124000 23800 66800 7850 25900 22100Sc 31 7 3Ba 5667 1390 1900 2030 359 484 1220 1070 424Rb 109.6 54 82 13.2 3 19 25 25 27Sr 45.8 5 37 6.2 6 5 5 5 5Nb 12.2 5 5 9.5 2 7 5 6 5Zr 118.5 58 81 31.2 36 38 63 40 50Y 24.5 6.8 16Th 0 5 5 0 0 1 1 1 1U 0 0.3Ce 79 22 18Sample is from chert overlyinging the main Battle massive suiphide lensIOLTABLE 5.3 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THEPUMICEOUS LAPIILI TUFF (PLT) BATTLE ZONE, BUTI1E LAKE MINING CAMP, SOUTHWESTERNBRITISH COLUMBIA.Unit PLT PLT PLT PLT PLT PLT PLT PLT PLTSample 67W 1O6WR 34W 46W 33W 20W 26W 54W L1B78Lab Code BARR 106 94-096Section 1585 1798 1585 1585 1585 1585 1585 1585 1372Drillhole 14-904 14-918 14-907 14-906 14-907 14-910 14-912 14-905Depth(ft) 823 975 834 852 834 968 1003 828Depth(m) 250.9 297.3 254.3 259.8 254.3 295.0 305.8 252.3 0.0Weight %SiO2 64.30 62.73 60.50 60.70 59.80 70.20 57.90 65.90 53.97TiO2 0.51 0.50 0.50 0.56 0.51 0.39 0.54 0.35 0.59A1203 18.30 19.81 19.20 20.60 19.80 14.90 19.80 18.40 23.56Fe203 5.05 4.25 4.49 4.24 4.97 3.30 4.09 3.34 7.67MnO 0.02 0.00 0.03 0.02 0.03 0.02 0.02 0.03 0.01MgO 0.65 0.43 0.92 0.68 0.84 0.49 0.80 0.84 0.32CaO 0.11 0.11 0.34 0.44 0.26 0.17 0.26 0.28 0.14Na20 0.26 0.80 0.52 0.41 0.42 0.27 0.55 0.28 0.22K20 4.95 5.41 5.06 5.39 5.38 4.06 5.55 4.90 6.260.09 0.09 0.12 0.20 0.13 0.08 0.14 0.09 0.1LOI 4.75 4.69 4.85 4.70 5.10 3.65 5.15 4.00 6.62Sum 98.989 98.821 96.526 97.942 97.243 97.525 94.796 98.41 99.46ppmCr2O3 154 74Ni 16 19Co 14 1V 40 55Cu 13 320 533 221 373 299 719 1080 139Pb 14 9 2 10 5 10 41 12 36.9Zn 35 12558 6690 2980 3800 906 14700 523 48Ga 26.8 25.5S 11700 10800 50200 25 17400 32100 19200 25Sc 14 14Ba 2480 548 4210 3480 4420 3150 3290 2890 2962Rb 74 9.0 74 76 79 59 67 75 71.9Sr 5 28.8 27 32 17 22 26 18 31.9Nb 8 8.9 8 9 11 7 8 9 9.2Zr 142 146.2 157 125 160 132 149 157 197.8Y 13 29.1 21.8Th 1 9.7 1 6 7 6 1 5 0.2U 7.8 13.4Ce 69it3TABLE 5.4 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THERHYOLITIC TUFFACEOUS SEDIMENTS (RTS), BATTLE ZONE, BUTLE LAKE MINING CAMP,SOUTHWESTERN BRITISH COLUMBIA.Unit RTS RTS RTS RTS RTS RTS RTS RTS RTSSample 76W 18W 32W 220WR 31W 153WR 132WR 118WR I71WRLab Code 94-090 BARRT53 BARRL32 BARRI18 BARRL71Section 1585 1585 1585 1372 1585 1798 1798 1798 1798Drillhole 14-900 14-910 14-907 14-751 14-907 14-915 14-917 14-919 14-920Depth(ft) 810 929 808 844.5 774 860 952 953 710Depth (m) 247.0 283.2 246.2 257.5 236.0 262.2 290.2 290.5 216.5Weight %Si02 76.80 74.70 61.40 86.87 57.70 58.04 78.61 71.95 72.08Ti02 0.25 0.26 0.37 0.18 0.40 0.39 0.25 0.48 0.31A1203 11.80 14.10 18.80 7.55 23.10 19.43 9.86 19.15 16.87Fe203 3.30 2.34 2.26 1.24 4.04 9.50 2.63 0.25 1.91MnO 0.01 0.02 0.09 0.02 0.01 0.00 0.18 0.00 0.01MgO 0.28 0.55 2.73 0.48 0.60 0.53 1.02 0.29 0.61CaO 0.11 0.06 1.07 0 0.22 0.00 1.01 0.02 0.18Na20 0.28 0.34 0.46 0.09 0.65 0.16 0.01 0.00 0.12K20 3.00 3.61 4.51 1.75 5.50 5.30 2.59 5.20 4.44P205 0.06 0.03 0.06 0.01 0.06 0.01 0.04 0.04 0.04LOl 3.10 2.95 4.05 1.44 5.05 6.97 3.48 2.47 3.15Sum 98.99 98.961 95.796 99.63 97.33 100.331 99.68 99.852 99.72ppmCr203 212Ni 0Co 1V 5Cu 10 16 313 84 109 70 49 45 79Pb 25 329 7 166.9 1130 59.6 15.4 2.2 5.5Zn 28 445 2660 426 651 116 50 17 32Ga 8.1 19.1 11.2 18.6 15.9S 6470 25 2370 3710 16400 3990 5360 25Sc 6Ba 1150 4090 3540 5748 11100 2819 2506 2365 4252Rb 50 53 78 20 69 62.1 34 61.5 59.8Sr 45 32 22 88.7 126 29.2 26.4 24 32.6Nb 7 9 10 10.4 14 8.2 10.2 12.5 11.1Zr 110 128 161 75.7 241 160.8 88.4 183.1 165.5Y 16.1 19.6 22.8 47.1 34.6Th 3 4 2 0 16 14.9 2.4 2.8 4.6U 0 9.7 0 0 0Ce 10CLITABLE 5.5 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM H-WMAFIC SILL, BATI’LE ZONE, BUTLE LAKE MINING CAMP, SOUTHWESTERN BRITISH COLUMBIA.Unit Mafic Mafic Mafic Mafic Malic Malic Mafic Mafic MaficSample 1O4WR 1O3WR 22W 80W 21W 115WR 70W 69W 45WIb CodeSection 1798 1798 1585 1585 1585 1798 1585 1585 1585Drillhole 14-918 14-918 14-910 14-900 14-910 14-919 14-904 14-904 14-906Depth(ft) 907 893 1079 965 1052 868 975 960 800Depth (m) 276.5 272.3 329.0 294.2 320.7 264.5 297.3 292.7 243.9Weight %Si02 36.44 72.84 35.90 58.90 42.40 49.21 27.20 57.70 60.90Ti02 1.10 0.55 1.60 0.83 1.41 1.11 0.86 0.58 0.74A1203 24.57 12.06 38.20 18.70 30.40 26.46 17.30 12.00 17.40Fe2O3 17.64 5.47 5.19 3.23 6.68 7.07 31.00 14.70 7.61MnO 0.02 0.02 0.01 0.16 0.01 0.01 0.01 0.01 0.01MgO 0.95 0.48 0.24 1.68 0.75 0.68 0.45 0.22 0.47CaO 0.42 0.76 1.16 2.44 0.45 0.37 0.66 1.17 0.15Na20 0.32 0.00 0.47 0.33 0.48 0.34 0.31 0.20 0.38K20 6.60 3.23 7.89 5.04 8.27 7.21 4.63 3.07 4.520.18 0.40 0.88 0.25 0.30 0.20 0.50 0.83 0.15LOl 11.79 4.25 6.80 4.05 7.40 6.63 17.10 8.80 5.95Sum 100.03 100.061 98.34 95.611 98.55 99.29 100.024 99.284 98.277ppmCr2O3 360 376Ni 16 25Co 29 16V 257 101Cu 989 371 17 265 174 3003 6450 1060 600Pb 22.3 11 3 5 12 24.2 8 4 15Zn 37 55 27 46 627 123 118 48 2410Ga 27.3 29.5S 941 1320 25 12100 10900 19200 7430 7830 6760Sc 24 21Ba 3738 2060 3650 1870 3600 3543 1140 715 3540Rb 85.8 47 85 68 125 89.3 75 42 66Sr 41.3 26 84 66 58 40.6 23 18 5Nb 10.3 3 7 9 14 15.5 11 9 8Zr 97 63 111 173 216 213.4 148 117 114Y 25 19 37.1Th 8.6 2 1 8 9 0 4 1 5U 6.8 2.4Ce 76 85Weight %Si02Ti02A1203Fe203MnOMgOCaONa20K20LOlSumppmCr203NiCoVCuPbZnGaSScBaRbSrNbZrYThUCe83.170.17.54.160.010.180.2601.980.192.8100.352613623619.7619.3083026.513.210.481.913.801.61978.20 83.290.20 0.1210.80 10.260.75 1.630.06 00.42 0.131.81 0.015.00 0.10.75 2.690.05 0.010.65 1.9698.689 100.2164012228 4413 6.837 11311.4585006661 116119 36.1146 226 11.681 103.410.51 0025TABLE 5.6 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCFIEMICAL SAMPLES FROM H-WMAFIC SILL AND THE QUARTZ PORPHYRITIC (QP) RHYOLITE, BATTLE ZONE, BUTLE LAKEMINING CAMP, SOUTHWESTERN BRITISH COLUMBIA.Unit Mafic Mafic Mafic Mafic Mafic QP QP QP QPSample 116WR 56W 71W MRI 225WR 204WR 203WR 79W L1898Lab Code BARR1 16 94-098 94-091 94-087 94-086 94-097Section 1798 1585 1585 1372 1402 1402 1585Drillhole 14-919 14-905 14-904 14-750 14-753 14-720 14-720 14-900Depth(ft) 907 902 988 980 879 733 925 927Depth (m) 276.5 275.0 301.2 298.8 268.0 223.5 282.0 282.6 0.044.31 42.40 47.80 51.89 39.82 85,960.73 1.13 1.25 1.18 1.31 0.1522.55 25.20 29.70 27.64 28.46 8.2114.18 13.30 4.26 4.75 11.65 1.50.02 0.01 0.01 0 0 0.011.18 0.42 0.43 0.27 0.38 0.160.19 0.04 0.88 0.06 0.42 0.040.48 0.42 0.59 0.53 0.51 0.196.05 6.57 7.75 6.98 7.6 1.980.08 0.06 0.65 0.07 0.32 0.019.88 9.35 5.70 5.86 9.07 1.5599.65 98.9 99.02 99.23 99.54 99.76260 27 86 89918 0 0 915 6 9 0143 72 332 13247 5130 29 52 135 6734.8 21 9 18 20.1 25.65073 198 23 22 588 380025.9 26.3 25.5 12.41380 27900 2430011 19 23 52265 1700 1660 4904 2368 191176.3 96 121 84.1 89.2 24.334.9 30 58 49.4 41.1 26.39.7 12 13 15.7 10.5 13.5129.9 222 220 234.7 114.3 87.629.2 58.8 33.6 13.31.9 10 11 0 0 04.6 3.1 092 101 67 40TABLE 5.6 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THEQUARTZ PORPHYRITIC (QP) AND QUARTZ FELDSPAR PORPHYRITIC RHYOLITE, CONTINUEDUnit QP QP QP QFP QFP QFP1 QFP1 QFP1 QFP1Sample L1B98 206WR 68BW 81W 16OWR D39903 PR7554 P118G D13625Lab Code 94-097 94-088 BARR16OSection 1402 1585 1585 1798Drillhole 14-720 14-904 14-911 14-914Depth(ft) 688 913 935 610Depth (m) 0.0 209.8 278.4 285.1 186.0 0.0 0.0 0.0 0.0%44.89 77.300.52 0.1926.91 12.408.71 1.660.01 0.010.51 0.320 0.011.7 0.196.26 3.220.01 0.037.58 2.5597.1 97.877WeightSi02Ti02A1203Fe203MnOMgOCaONa20K20LOISumppmCr203NiVCuPbZnGaS78.70 66.48 81.5 72.60.20 0.28 0.12 0.2210.90 11.34 9.95 16.60.70 11.13 1.32 1.950.06 0.00 0.02 0.010.38 0.18 0.31 0.281.82 0.33 1.65 2.625.14 0.10 4.22 2.520.75 2.93 0.84 30.05 0.00 0.04 0.050.55 7.0499.253 99.81 99.97 99.8583.290.1210.261.6300.130.010.12.690.011.96100.21640122446.811311.4780.1712.81.180.030.441.274.711.390.0571.70.2314.12.480.040.662.95.961.90.0984224643342951.31696142.8100.04 100.06182 1 2115 4 88.226 30 7538.112900 5000 10200684 557221 30.8155 121.28 7.2116 109.411.64 4 13.29Sc 6Ba 1161Rb 36.1Sr 22Nb 11.6Zr 103.4Y 10.5Th 0U 0Ce 25Analysis is fron Juras (1987).346614 42190 89590 13014 22146616 11000 56109 50 9198.2 13919.719.41671927921031243350313520I0’7ppmCr203NiCoVCuPbZnGaSScBaRbSrNbZrYThUCe468 71821 9210 1122 2822 48 965.7 12252 31517.4 17.24330 274005 75044 805041 60.5 70.6225 44.3 129.83 11.6 11.5145 183.1 201.416 39.3 32.95.8 6.92.2 1.1110 94633 358 57022 11 262 4 817 25 28181 55 183546.1 11.8 87.3867 60 240412 17.5 19.67250 25 180005 10 42841 4366 554317.2 71.9 67.919,2 89.5 48.27.9 11 10.892.4 186.5 195.313.4 34.5 25.86.9 6.70.3 1.5 5.398 103 130569 54625 167 728 2774 3117.5 21.283 4718.1 19.91350 753005 65749 602271.7 80.461.2 29.911.1 11.7203.1 210.935.6 36.58.9 8.22.9 3122 122TABLE 5.6 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THEQUARTZ FELDSPAR PORPHYRITIC RFIYOLITE, CONTiNUEDUnit QFP1 QFP QFP QFP QFP QFP QFP QFP QFPSample D1412A 112WR 1O1WR 161WR 131WR 17OWR L1B74 111WR 162WRL.abCode BARRII2 BARR1O1 BARR161 BARR131 BARR17O 94-095 BARR1LI BARR162Section 1798 1798 1798 1798 1798 1372 1798 1798Drillhole 14-919 14-918 14-914 14-917 14-920 14-753 14-919 14-914Depth(ft) 758 805 623 892 614 728 725 635Depth(m) 0.0 230.9 245.4 189.9 272.0 187.2 222.0 221.0 193.6Weight %Si02Ti02p203Fe2O3MnOMgOCaONa2OK2OLOISum70.3 63.14 65.610.26 0.38 0.4614.2 19.83 20.424.09 3.08 2.240.05 0.09 0.000.86 3.96 0.501.59 0.07 0.444.27 0.22 0.524.26 4.27 4.910.1 0.05 0.014.31 4.0699,98 99.4 99.17183.24 61.95 62.940.19 0.38 0.409.65 20.03 20.711.92 2.79 4.110.00 0.10 0.000.20 2.36 0.540.00 1.58 0.050.10 0.49 0.412.56 4.87 5.520.00 0.05 0.002.09 4.95 4.6799.95 1 99.55 99.3559.58 61.050.43 0.4521.17 22.743.81 3.460.08 0.002.72 0.840.79 0.010.28 0.515.01 6.350.06 0.045.26 4.5899.19 100.0373.220.2112.941.520.071.281.750.163.440.044.1898.8113600153451611.27512042.649.912121.2280025Analysis is fron Juras (1987).1 1 1 1 1 19 1 216 36118 7 1 1 7 8 1 117 58337 82 31 48 27 53 54 3300 10800GaS 1010 134000 18700 7700 14700 13800 80800 20300 24400Sc3800 3890 1150 1300 2240 3450 2930 2620 598035 82 32 40 38 52 29 52 53137 74 68 73 95 54 121 28 1458 10 9 9 8 8 8 9 981 236 124 145 137 121 94 161 165YTh 3 7 3 6 6 6 1 8 15UTABLE 5.6 MAJOR AN]) TRACE ELEMENT DATA FOR LITHOGEOCUEMICAL SAMPLES FROM THEQUARTZ FELDSPAR PORPHYRITIC (QFP) RHYOLITE, CONTINUED....Unit QFP QFP QFP QFP QFP QFP QFP QFP QFPSample 24W 53W 02W 01W 64W lOW 42W 75W 52WLab CodeSection 1585 1585 1585 1585 1585 1585 1585 1585 1585Drillhole 14-912 14-905 14-905 14-905 14-904 14-909 14-906 14-900 14-905Depth(ft) 943 730 760 760 655 845 659 745 656Depth (m) 287.3 222.6 231.7 231.7 199.7 257.6 200.9 227.1 200.0Weight %Si02 82.40 56.70 76.40 73.90 74.60 72.70 81.40 69.30 62.20TiO2 0.15 0.42 0.22 0.25 0.24 0.27 0.17 0.29 0.36203 9.49 23.60 12.10 13.30 13.50 13.10 8.70 15.70 17.30Fe203 0.85 3.36 1.29 1.74 1.28 2.45 1.38 3.46 4.15MnO 0.17 0.03 0.04 0.03 0.02 0.32 0.04 0.02 0.01MgO 1.13 1.63 0.43 0.43 0.47 0.94 1.70 0.81 0.53CaO 1.70 1.58 1.37 1.42 1.02 1.23 0.43 0.22 0.50Na20 0.11 0.71 3.06 2.86 2.97 0.25 0.68 0.43 0.88K20 1.93 5.95 2.12 2.47 2.24 3.42 1.01 3.99 3.86“25 0.04 0.06 0.05 0.06 0.08 0.06 0.04 0.06 0.09LOl 1.80 4.85 1.55 1.90 1.80 3.05 2.45 3.95 5.20Sum 99.766 98.888 98.625 98.359 98.219 97.786 97.998 98.233 95.075ppmCr2O3NiCoVCuPbZnBaRbSrNbZrCeGaSScBaRbSrNbZrYThUCe25 178005800 7490 2550 2600 9980 813057 62 34 26 61 69136 158 13 111 158 699 10 7 9 11 12157 239 85 122 208 21225 2840 1270866 3030 320039 50 44398 84 1058 10 9128 138 151TABLE 5.6 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THEQUARTZ FELDSPAR POPPFIYRITIC (QFP) AND GREEN QUARTZ FELDSPAR PORPHYRITIC (GQFP)RF{YOLITE, CONTINUED....Unit QFP QFP QFP QFP QFP QFP GQFP GQFP GQFPSample 65W 43W 66W 41W 29W 44W 61W 17W 03WLab CodeSection 1585 1585 1585 1585 1585 1585 1585 1585 1585Drillhole 14-904 14-906 14-904 14-906 14-907 14-906 14-904 14-910 14-908Depth(ft) 748 713 770 635 742 745 606 890 734Depth (m) 228.0 217.4 234.8 193.6 226.2 227.1 184.8 271.3 223.8Weight %Si02Ti02A1203Fe203MnOMgOCaONa20K20LOlSumppmCr203NiCo66.90 57.30 80.50 75.40 59.700.27 0.44 0.14 0.23 0.4015.80 24.80 7.75 12.30 21.601.33 4.30 2.91 2.05 4.230.07 0.01 0.01 0.04 0.020.52 0.81 0.18 3.00 1.543.30 0.15 0.05 0.15 0.080.30 1.35 0.29 0.97 0.714.05 4.49 1.94 1.34 4.780.05 0.03 0.03 0.02 0.031.95 5.45 2.80 3.05 5.0594.541 99.125 96.602 98.551 98.14461.60 73.400.40 0.2522.00 12.103.35 1.860.01 0.060.70 0.670.01 3.630.69 2.235.06 1.840.03 0.054.50 1.2598.354 97.3470.900.2413.302.000.112.851.830.292.780.062.6597.01371.200.2614.502.160.062.601.140.712.550.063.0598.294I157VCu 1 7 101Pb 30 18 1250Zn 106 48 72601 1211 4673 1121610 10600 86900 1070013 1 166 5 679 45 1134 8 12 4 4 10 1 3 3HOTABLE 5.7 MAJOR AND TRACE ELEMENT DATA FOR LITHOGEOCHEMICAL SAMPLES FROM THEGREEN QUARTZ FELDSPAR PORPHYRITIC (GQFP) RHYOLITE AND THE HANGINGWALL M4DESITE(HWAN)Unit GQFP GQFP GQFP GQFP GQFP GQFP GQFP QFPD HWAN HWANSample 09W 159WR 63W 62W 207WR 30W 74W 227WR 14OWR 13OWRLab Code I3ARR15 94-089 94-092 BARR14 BARRI39 0 0Section 1585 1798 1585 1585 1402 1585 1585 1372 1798 1798Drillhole 14-909 14-914 14-904 14-904 14-720 14-907 14-900 14-753 14-916 14-917Depth(ft) 811 536 633 617 623 760 560 668 939 803Depth(m) 247.3 163.4 193.0 188.1 189.9 231.7 170.7 203.7 286.3 244.8Weight %Si02 64.90 73.34 80.10 81.10 73.65 75.00 71.40 64.38 51.07 51.86Ti02 0.31 0.27 0.20 0.18 0.24 0.25 0.23 0.26 1.20 0.73A1203 17.40 15.58 10.20 8.98 13.23 14.10 12.90 16.59 15.29 17.68Fe203 2.27 0.94 1.03 1.33 2.53 2.39 2.54 3.49 11.26 9.33MnO 0.17 0.00 0.03 0.04 0.04 0.01 0.08 0.13 0.23 0.14MgO 2.92 0.35 0.75 0.70 2.6 0.45 0.80 1.32 4.18 5.04CaO 1.76 1.00 0.83 1.86 1.28 0.05 4.19 3.1 5.99 5.59Na20 0.35 3.90 5.26 3.82 0.39 0.33 2.14 3.24 2.67 4.11K20 3.94 2.48 0.24 0.53 2.27 3.46 1.99 2.58 0.88 0.410.08 0.04 0.05 0.04 0.04 0.05 0.05 0.15 0.41 0.21LOT 3.60 2.03 0.45 0.45 3.3 3.00 0.55 4.42 6.82 5.15Sum 97.703 99.93 99.135 99.029 99.57 99.087 96.874 99.66 100 100.25ppmCr203 262 95 107 76 47Ni 8 0 0 23 18Co 6 6 0 33 28V 69 24 36 261 196Cu 3 22 1 1 49 17 1 34 256 112Pb 50 6.9 1 1 8.6 29 4 2.6 6 8.2Zn 150 27 46 54 217 119 70 95 271 196Ga 16.2 12.1 14.7 16 15.6S 46200 6300 14000 118000 131000 4330Sc 6 13 8 28 22Ba 6290 1243 196 519 4051 7860 669 603 354Rb 62 34.3 20 33 32.9 67 41 46.6 11.1 4.2Sr 223 99.2 94 115 74.7 74 465 175.6 153.6 302.5Nb 8 10.7 8 9 11.5 10 8 11.4 8.5 6.4Zr 165 148.7 115 103 130.7 133 141 75.5 127.9 57.4Y 20.8 29 17.5 34.3 25.4Th 7 2.1 4 7 0 7 5 0 17.8 9.9U 0.5 0 0 5.9 1Ce 49 81 46 55 34illTABLE 5.8. TRACE AND RARE EARTH ELEMENT DATA FOR SELECrED SAMPLES FROM THEBATTLE ZONE, BliThE LAKE MINING CAMP, NORTHWESTERN BRITISH COLUMBIA.Unit PRICE PRICE PRICE CHERT QP QP QFP QFP QFP GQFP GQFP QFPDSample 229W 157W 184W 11W 68BW 203W 01W UB74 81W 61W 63W 227WR R R R RLab Code 94-099 BARRI57 BARRIB4 94-086 94-095 94-092Section 1798 1798 1585 1585 1402 1585 1372 1585 1585 1585 1372Drillhole W190 14-915 14-913 14-909 14-904 14-720 14- 14-753 14- 14-904 14-904 14-753905 911Depth (ft) 2704 934 830 876 913 925 760 728 935 606 633 668Depth (m) 824.4 284.8 253.0 267.1 278.4 282.0 231.7 222.0 285.1 184.8 193.0 203.7ppmAs 3 111 22 3 13 29 3 5 5 2 2 1& 25.8 25.5 19.8 5.5 3.5 2.1 5.5 7.4 4.5 5.5 4.4 4.6Sb 0.5 1.3 0.5 0.6 0.4 2.7 0.3 0.3 0.5 0.6 0.1 0.2Au 3 449 54 57 7 117 6 14 1 4 3 1Rb 7.2 70.6 44.1 25 56 26.5 40 42.6 21 39 20 46.6Sr 407.7 58.3 24.1 5 5 13.2 73 49.9 155 398 94 175.6Th 0 11.9 12.7 1 4 0 6 0 4 1 4 0U 0.8 4.2 0.6 1.3 2.5 1.8 ii 1.5 1.2 1.3 1.4 1.5Cs 0.6 0.5 0.6 0.6 0.3 0.4 0.4 0.1 0.1 0.6 0.1 0.9Hf 2.2 3.1 1.2 3.1 3.3 2.1 3.4 3.2 2.6 3.1 2.6 1.8La 13.9 17.6 7.3 7.9 17 2.3 24 24.9 13.5 17.9 12.5 16.2Ce 31 35 19 15 35 5 44 49 27 35 23 31Nd 17 18 11 7 14 4 19 21 13 15 9 13Sm 4.22 3.96 2.56 1.27 2.32 0.95 3.4 3.87 2.41 2.89 2.12 2.37Eu L34 1.18 0.46 0.21 0.52 0.34 0.82 1.11 0.63 0.72 0.43 0.7Th 0.8 0.8 0.4 0.2 0.4 0.3 0.6 0.8 0.6 0.6 0.4 0.4Yb 2.58 2.74 1.41 0.66 1.48 1.14 2.6 2.96 2.81 2.63 3.28 1.63La 0.37 0.4 0.22 0.11 0.22 0.18 0.38 0.42 0.43 0.39 0.54 0.255.2 ELEMENT BEHAWOURMethods for analyzing geochemical data in altered rocks rely on the use of immobile andincompatible elements (MacLean and Barrett, 1993; Stanley and Madeisky, 1994). In Chapter 4(section 4.4) the elements Zr and Y were found to be incompatible in the Price andesite; Ti and Zraxe incompatible in the H-W rhyolite. In addition, Al and Nb have also been found to be immobileunder typical conditions of hydrothermal alteration and gieenschist grade metamorphism involcanogenic deposits in the Abitibi region (MacLean and Kranidiotis, 1987; MacLean, 1990;Barrett and MacLean, 1991; Barrett et a!., 1991, 1992; Shriver and MacLean, 1993).Element mobility in a single rock unit can be tested by plotting element pairs ofconcentration data. Immobile element pairs will form a highly correlated linear trend owing to1mass gains and losses of mobile components in the altered part of the rock unit; at infmite massgain, the line ideally passes through the origin (Grant, 1986). If both elements are alsoincompatible, multiple rock units related by fractionation also plot along highly correlated linearirends. If one element is compatible, a fractionation curve will be defined by the least alteredsamples. Altered samples will lie along a series of alteration lines, one for each rock unit in thefractionation series that intersects the fractionation curve at some angle (MacLean and Barrett,1993, figure 5, page 116). In the Battle zone, the element pair Ti-Zr (Figure 5.1) illustrates theserelationships.5.2.1. TiversusZrFigure 5.1 is a plot of all the Ti02-Zr data for the Battle zone and least altered samples ofPrice andesite and QFP rhyolite from Juras (1987; Tables 5.1 to 5.7). This diagram discriminatesbetween three different lithologies in the altered rocks: rhyolite, Price andesite and H-W mafic.The rhyolite data form both a linear trend and a separate cluster. Samples from the rhyolite flow-dome complex (triangles: QP, QFP, GQFP) form a tight linear array. Tuffaceous rhyolite units(circles: fine rhyolite tuffaceous deposits, chert and rhyolite tuffaceous sediments) mostly plotabove this array, and there is more scatter in the data. The circular cluster above the rhyolite line(male symbols) is from pumiceous lapilli tuff, a pyroclastic marker horizon. Data from the Priceandesite (stars) plot along a steep fan-shaped trend. Analyses from the H-W mafic unit (asterisks)plot mainly within a fan-shaped trend of lesser slope than the Price andesite, with several datapoints spread over the diagram.Least altered samples of QP, QFP and GQFP plot close to the origin in Figure 5.1. Samplesthat plot along the line to the right of the least altered samples have been altered by loss ofmaterial whereas samples that plot to the left have been altered by addition of material, The onlysamples showing significant mass gain are cherts, which have had silica added to them. Clearlymost of the variation in Ti02 and Zr in the rhyolite units is due to residuali3Figure 5.1. Plot ofTi02 versus Zr for all the samples from the Battle zone, Buttle Lake miningcamp, central Vancouver Island, southwestern British Columbia. Data from Juras (1987; Table4.1) are also included on this diagram. The plot discriminates between the three main lithologies:rhyolite, Price andesite and H-W mafic. Data from the rhyolite flows form a highly correlatedlinear trend (triangles). A separate cluster is formed by the pumiceous lapilli tuff (male symbols).Felsic tuffs plot below the pumiceous lapilli tuff (diamonds). Price andesite data (stars) form afan-shaped array through the origin. Analyses from the H-W mafic unit (asterisks) spread overthe diagram, but plot mainly within another fan that projects to the origin. Fractionation trendsfor the Price andesite and H-W horizon rhyolite are drawn in bold ink.Iiiq2.01.5 - -+ Price andesite*-I---, ** 9 •. *•mafic -I— * **,c1Q *05 - * ft * 9* * V -VV0.00 50 100 150 200 250Zr (ppm)“5increase or decrease of those elements during metasomatism as the range ofTi02 and Zr valuesdue to fractionation is limited.T102 is compatible in the Price andesite, as a result, least altered samples are scatteredparallel to the Ti02 axis. Altered samples lie along a series of alteration lines through the originwithin the range ofTi02-Zr defined by the least altered samples, therefore both Ti and Zr areimmobile (cf MacLean and Barrett, 1993). Those samples that plot below the curve towards theorigin have gained mass; those above the least altered samples have lost mass. Compared to therhyolites, which have mostly undergone mass loss, much of the Price andesite has been affected bymass gain.Data from the H-W mafic sill is difficult to interpret because it is extremely altered in theBattle zone. However, it is broadly characterized by high Zr and low Ti contents compared to thePrice andesite. It could be a late, relatively fractionated phase of the Price andesite; alternativelyit could represent a high Zr magma that is unrelated to the Price formation. Al/Zr ratios (Table5.5) in samples from the mafic sill are variable, but lower than or equal to, those in the Priceandesite (Table 5.1). This would be consistent with feldspar loss during fractionation, and thehypothesis that it is a late phase of the Price; but this cannot be proved.5.2.2 Rare Earth ElementsRare earth element plots of least altered and altered rocks from the Price andesite and H-Whorizon rhyolite are plotted in Figures 5.2a and b, respectively. The least altered analysis(229WR; Table 4.1) from the Price andesite forms a gently sloping, almost flat profile. Sample1 57WR (Table 5.8) plots slightly above the least altered analysis, and 1 84WR (Table 5.8) plotsbelow. REE abundances have been diluted by addition of quartz and pyrite in 1 84WR, andenhanced by sericitization (mass loss) in 1 57WR. The slopes of the patterns are different at thelight REE end, perhaps indicating mobility of the light REE. Eu in particular has been depleted inthe silicifled sample (1 84WR).I I(Figure 5.2. Rare earth element plots normalized to Sun (1980) for samples from the Battle zone,Buttle Lake mining camp, southwest British Columbia. (a) Price andesite. Least altered sample(229WR; filled diamonds), silicified and pyritized sample (1 84WR; filled circles), and sericitizedsample (1 57WR; filled circles). (b) H-W horizon rhyolite and chert.I7100101100101•229WP • 1 57WR • 1 84WRLa Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu‘81W •O1W 011W—-I I I I I I I I I I I I Ia: Price andesiteI I I I I I I I I I I I I II I I I I I I I I I I I Ib: H-W horizon rhyoliteLa Ce Pr Nd Sm Eu GdTb Dy Ho Er Tm Yb LulISimilar patterns are apparent for the rhyolite samples from H-W horizon. The least alteredanalysis from the QFP (8 1W; Table 4.1) plots between the two altered analyses. Moderatelysericitized QFP (01W; Table 5.8) plots above the least altered analysis at the light REE end.However, the heavy REE values are virtually identical between the least altered and moderatelysericitized sample. An analysis of chert (11W; Table 4.1) is also shown on Figure 5.2b. It plotsbelow but subparallel to the rhyolite, indicating addition of mass to a rhyolite component hasoccurred. The REE profile is parallel to the QFP profile at the heavy REE end. However, thedistance between the two profiles decreases at the light REE end, indicating mobility of the lightREE.5.3 FOOTWALL ALTERATION: PRICE FORMATION5.3.1 Hand specimen and thin section descriptionAlteration within the Price formation andesite forms a large, stratabound zone (Figure 6.1).The alteration assemblage is quartz-sericite-pyrite with minor chlorite and varies in intensity fromtotally to weakly altered. Totally altered rocks (Plate 5.1 a) occur immediately below massivesuiphide lenses for thicknesses between 10 and 25 m (see Figure 6.1; stockwork mineralization).Original textures are completely destroyed such that the rocks are not recognizable as maficvolcanic rocks. Rocks in this zone consist of 30 to 60% quartz-pyrite stringers and pyritedisseminations in a pinkish, foliated matrix of quartz and coarse grained sericite. Thedisseminated pyrite is also coarse grained, forming porphyroblasts up to 1 centimetre across (Plate5. lai). Locally, pyritic stringers may contain up to 5% chalcopyrite. Moderately altered rockbelow the totally altered rock forms a stratabound zone between 15 and 30 m thick. Thealteration consists of 10-30% pyrite stringers in sericitized, but recognizable, pale to dark greenandesite (Plates 5. lb and b1). Weakly altered rocks contain less than 10% disseminated pyrite.Primary volcanic textures such as quartz-chlorite filled amygdules are preserved (Plates 5.1 c andci). Breccias and flow units can also be recognized.119Plate 5.1. Alteration facies within the Price formation andesite, Buttle Lake mining camp,southwestern British Columbia. Dime is 8 mm across. Photomicrograph fields of view are about2 mm across. (a) Extreme quartz-sericite-pyrite alteration (DDH 14-908, 277 m or 909 feet).No primary textures are preserved in this specimen. (ai) Photomicrograph of rock destructivequartz-sericite-pyrite alteration (DDH 14-918, 308 m or 1011 feet, crossed polars). Coarsegrained yellow to blue sericite, white to pale yellow quartz and pyrite euhedral (black) comprise100% of the rock. (b) Moderate quartz-sericite-pyrite alteration (DDH 14-906, 309 m or 1015feet). Saussuritized feldspars are visible in this specimen. (b1) Photomicrograph of moderatequartz-sericite-pyrite alteration, same sample (crossed polars). Local patches of altered andesiteare intact. (c) Weakly altered andesite flow unit (DDH 14-905 322 m or 1055 feet). Specimen ispervasively sericitized and contains 2% disseminated pyrite. Amygdules and relict mafic minerals(pyroxenes?) are visible. (c1)Photomicrograph of weakly altered flow unit, same sample (planelight). Amygdules are filled mainly with sericite and quartz.2I5.3.2 Chemical PatternsLeast altered rocks from the Price andesite are related by fractionation of feldspar,pyroxene, olivine and Fe-Ti oxides (section 4.4.1). Because feldspar and clinopyroxene are thedominant phenocrysts, most chemical variation in the least altered samples is due to sorting ofthese minerals. A plot of(2Ca-fNa+K)/Zr PER versus Al/Zr PER (Figure 5.3) describes thestoichiometry of plagioclase and clinopyroxene. It is insensitive to fractionation of olivine or Fe-Ti oxides because neither Fe, Mg, Si nor Ti is plotted on either axis.Analyses that depart from the fractionation model must have undergone material transfer ofat least one of the numerator elements on Figure 5.3. Most of the data plot within the same rangeof Al/Zr PER values as the least altered samples, indicating that Al is relatively immobile in thealteration zone. Therefore, addition or loss of the elements Ca and Na or K must have occurredin the altered rocks. All the analyses from the Battle zone plot below the least-altered rocks inFigure 5.3 along a line with a slope of 1/3. This line describes the stoichiometry of sericite(‘sericite line’), which contains 1 mole of K for every 3 moles of Al. Loss ofNa and Ca could beachieved by the conversion of albite or anorthite to sericite according to reactions 1 and 2(Stanley and Madeisky, 1994), respectively:3NaAlSiO8+ K + H KA135jO10(OH)2+ 3Na + 6SiO2 (1)3CaAl2SiO8+ 2K + 4H * 2KA1Si10(OH)+ 3Ca (2)The first reaction liberates Na and produces quartz. The second reaction releases Ca and K isadded by the hydrothermal fluid. Clinopyroxene does not produce muscovite because it does notcontain Al (except where Al substitutes for Si) and Al is immobile in the Battle zone. However,in an acid solution, clinopyroxene can break down to quartz and calcium and iron and magnesiumions can be released into solution (C. Stanley, pers. comm, 1994), perhaps according to:3Ca(Fe, Mg)Si206+ 12 H+ 35i02+ 3Ca + 3Mg + 3Fe + H20 (3)IFigure 5.3. Pearce element ratio (PER) diagram of (2Ca+Na+K)/Zr PER versus Al/Zr PER forall Price andesite data from the Battle zone and elsewhere in the Buttle Lake mining camp,southwestern British Columbia. Least altered rocks (Juras, 1987; Table 4.2) plot between a lineof slope 1 and a vertical line. These two vectors model fractionation of feldspar andclinopyroxene, respectively. The diagram is insensitive to fractionation of olivine or Fe-Ti oxidesbecause neither Fe, Mg, Si nor Ti is plotted on either axis.1230.9Price andesiteO.8O.7E_______a1yfica1O.5 FeldsParVVerrorAu-I0fractionation,ClinopyroxenefractionationAzO.3::Sjtttb0nAnlYfical error0• a I I I I I I0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Al/Zr PER (molar)I 2i-Addition or loss of any element, including those not on the axes ofFigure 5.3, can beshown by plotting bubbles representing those elements. The bubble area is proportional to theabsolute amount of the numerator element in that rock, and is calculated as follows:Bubble size = {[(EiJZr)- (Ei/Zr)mjn]/[(EiIZr)m - (EiJZr)mjn]}2+ K (B)where El/Zr is the Pearce element ratio of any element normalized to zirconium (in this case) andK is a small constant that ensures every data point is visible on the diagram. Differences in bubblesize must be caused by material transfer; either fractionation or metasomatism. By comparing thebubble size of an altered rock (one that plots on the sericite line) to a least-altered rock (one thatplots on or close to the fractionation line) addition or loss of the element in question may bedetermined by inspection. Because the bubbles are proportional to the Pearce element ratios, theyare proportional to the absolute amount of material transfer that has occurred in the sample(section 5.1).Bubble plots drawn for all the major elements and some trace elements are in Figures 5 ,4ato g. Less than half of the rocks in the footwall of the Battle zone have had silica added to them(Figure 5 .4a). Calcium is strongly depleted (Figure 5 .4b) in sericitized rocks, perhaps followingreaction 2, above. Sodium is also depleted during sericitization (Figure 5.4c), whereas potassiumis added (Figure 5.4d). Exchange ofNa and K might be described by reaction 1, above. The(K/Zr)PER bubble size increases systematically to the right on Figure 5.4d, therefore the amountof potassium added is directly proportional to the amount of Al in the rock. Barium and rubidiumexhibit the same trends as K because they are geochemically similar (Figures 5.4e and f).Microprobe analyses of sericite from the footwall are anomalous in Ba (Table 5.9), confirming theBa enrichment shown in Figure 5.4e. Unfortunately Rb concentrations in sericite wereundetermined because they are below the detection limit for electron microprobe analysis.Magnesium is depleted in most samples, (Figure 5.4g). However, a few show significant Mgaddition. Iron addition, shown in Figure 5.4h, reflects the occurrence of pyrite stringers.i25Figure 5.4. Pearce element ratio (PER) diagrams for all Price andesite data from the Battle zoneand elsewhere in the Buttle Lake mining camp, southwestern British Columbia. (a) Bubble plotwith bubbles scaled to Si/Zr PER value. Less than half of the rocks have had silica added to them.(b) Bubble plot with bubbles scaled to CaJZr PER value. Loss of calcium is almost complete inthe altered rocks.10.9cedit0.8rbubb1J0.77*06errorw00.5 Feldsparfractionation Clinopyroxenefractionation0.4z-4— Anal0 I0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Al/Zr PER (molar)10.9ceitj0.80.7/‘IalYIICal06w00.5 Feldsparfractionation Clinopyroxenefractionation0.4z0.3::00sttbon-I- Analytical errorI I I I I I0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Al/Zr PER (molar)12.7Figure 5.4. Pearce element ratio (PER) diagrams for all Price andesite data continued.... (c andd) Bubble plots with bubbles scaled to Na/Zr PER and K/Zr PER values, respectively. Alteredrocks have undergone almost complete loss ofNa and addition ofK. The amount ofK added isdirectly proportional to the amount of Al in the rock.Izs1•0.9 aI C: Price andesite0.8 Na/Zr bubbles-C._________FeldsparerrorUi00.5fractionation Clinopyroxenefractionationz0.30.2 0°SericitZration0.1-I— Afl lytical error0 I I0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9AVZr PER (molar)10.9ubbles0.8-S0.7error_,___/j1_&alYtlcal06Ui00.5 Feldsparfractionation • Clinopyroxenefractionation0.4z0.30.20.1-I- AnalI I I0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0,8 0.9AL’Zr PER (molar)12.9Figure 5.4. Pearce element ratio (PER) diagrams for all Price andesite data continued.... (e and f)Bubble plots with bubbles scaled to Ba/Zr PER and Rb/Zr PER values, respectively. Barium andrubidium have been substituted for potassium in sericite, thus they all exhibit the same pattern.10.90.80.70.600.50.4z÷0.30.20.10 I I I I0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Al/Zr PER (molar)0.90.80 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Al/Zr PER (molar)100.60.4z00.70.30.20.10130C: Price andesiteBa/Zr bubblesFeldsparfractionation • ClinopyroxenefractionationVcitZrafonf: Price andesiteRb/Zr bubbleserrFeldsparfractionation.ClinopyroxenefractionationAnalyt1 3’Figure 5.4. Pearce element ratio (PER) diagrams for all Price andesite data continued.,.. (g)Bubble plot with bubbles scaled to Mg/Zr PER value. (h) Bubble plot with bubbles scaled toFe/Zr PER value. Pyrite stringers and disseminations in altered andesite are marked by additionof iron.‘3210.9I g: Price andesite0.8 MgIZr bubbles0.7Feldspar06w00.5fractionation Clinopyroxenefractionationz0.30.2 eHcitZtion0.1•-l- Analytical error0 a I I I0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9AL’Zr PER (molar)10.90.8 ubbIJ0.706w00.5 Feldsparfractionation • Clinopyroxenefractionation0.4z0.3C..’0.2°ericitZZtioE0.1-I- Analytical errorA I I I I0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Al/Zr PER (molar)I335.4 HANGINGWALL ALTERATION: H-W HORIZON RHYOLITE5.4.1 Hand specimen and thin section descriptionAlteration within the H-W horizon rhyolite package is characterized by pervasivesericitization and pyrite disseminations (Plates 5.2a and ai) throughout most of the Battle zone.Most rocks within the horizon are recognizable as rhyolite because of the presence of quartzcrystals and flow banding. Sericite-sulphide stringers occur locally, particularly in the tuffaceousunits (Plates 5 .2b and b i)• Calcite occurs as rare veins and spherules (Plates 5 .2c and ci) withinthe green quartz feldspar porphyritic (GQFP) rhyolite.5.4.2 Chemical patternsFollowing the approach used for analyzing alteration in the Price andesite, the fractionationmodel for H-W horizon rhyolite (section 4.4.2) is used to assess the degree of metasomatism (cfStanley and Madeisky, 1994). Analyses from all the rhyolite samples in the Battle zone plotted ona (2Ca+Na+K)/Zr PER versus Al/Zr PER diagram (Figure 5.5) show two things: (i) data fromthe rhyolite flows and tuffs plot within the same range of Al/Zr PER values as the least alteredsamples, therefore Al is immobile in the alteration zone, and (ii) altered rocks plot along a line ofslope 1/3 that describes the stoichiometry of sericite. Because Al is immobile, alteration tosericite must have involved addition or loss of Ca, Na or K, perhaps according to reactions 1, 2(section 5.3), and possibly 3 (below):3KAISiO8+ 2H KA1SiO10(OH)2+ 2K + 6SiO2 (3)The distance the sample lies below the ‘feldspar’ line is proportional to how muchmetasomatism of Ca, Na and K has taken place (Stanley and Madeisky, 1994), if there is nocarbonate alteration in the rock. The effect of carbonate alteration on Figure 5.5 is to shift datapoints parallel to the ordinate; if CO2 analyses are available, the effect may be removed.i39Plate 5.2. Alteration facies of the H-W horizon rhyolite package. Dime is 8 mm across. (a)Variably sericitized green quartz feldspar porphyritic rhyolite (DDH 14-9 15, 203 m or 667 feet).White material is totally altered to sericite (SER). (ai) Photomicrograph ofvariably sericitizedquartz feldspar porphyritic rhyolite (DDH 14-907, 246 m or 806 feet, crossed polars). Brownfine-grained material is all sericite. Dark grey material is a granophyric matrix of fine grained,roughly equidimensional, recrystallized quartz and feldspar with a brown overprint of sericite.Grey crystals are quartz phenocrysts. (b) Suiphide-sericite stringers in rhyolite tuffaceoussediment (DDH 14-750, 253 m or 830 feet). (b1) Photomicrograph of sulphide-sericite stringer(SER) in rhyolite tuffaceous sediment (SED: DDH 14-917, 290 m or 952 feet). (c) Green quartzfeldspar porphyritic rhyolite with round spherules of carbonate (DDH 14-723, 200 m or 655 feet).(ci) Photomicrograph of carbonate spherule (crossed polars). Spherules have a radiatingextinction pattern and may be spherulites that have been replaced by carbonate.-‘ I- -13,Alteration of feldspar to sericite results in a net loss of two thirds of the available Na+K+2Ca in arock. Rocks in which feldspars have been completely sericitized plot two thirds of the way downfrom the feldspar fractionation line towards the abscissa. Thus, in Figure 5.5, sericitized samplesdefine a line of slope 1/3.As in the Price andesite, other elements are monitored by plotting them as bubbles withareas proportional to the individual PER values (equation B). These are drawn for all the majorelements and are shown in Figures 5.6a to h. Only cherts show significant silica addition (Figure5.6a). This is consistent with the Ti02 versus Zr plot (Figure 5.1) that indicates rhyolite isprimarily affected by net mass loss. Calcium and sodium is progressively depleted with the degreeof sericitization (Figure 5.6b and c, respectively), whereas potassium is added (Figure 5.6d).Exchange of Ca, Na and K can be described by reactions 1 to 3. Barium and rubidium exhibit thesame trends as K because they are geochemically similar (Figures 5 .6e and f). Microprobeanalyses of sericite from the hangingwall are anomalous in Ba (Table 5.10), confirming the Baenrichment shown in Figure 5.6e. Magnesium is depleted in most samples (Figure 5.6g).However, a few show significant Mg addition reflecting incipient chloritization. Iron addition inthe rhyolite (Figure 5.6h) is reflected by pyrite disseminations and stringers.Addition of silica without the effect of feldspar fractionation can be modeled. Anyplagioclase feldspar has the formula CaNa(J_)Al(J_)Si(3_)O8. Therefore,(SiIZr)PER = [(3-x)/(1+x)] * (A1/Zr)pER (C)where x is the percent anorthite in feldspar which may be determined optically or by electronmicroprobe analysis in sufficiently unaltered rocks. Battle zone rhyolite contains plagioclasefeldspar of composition An22 (Table 3.1), therefore the amount of Si in feldspar is proportional to(l.56AIIZr)pER. A plot of bubbles scaled to (Si/Zr)pER - (1.56A1/Zr)pER (not included) showsaddition of silica with the effect of feldspar fractionation removed. It is almost identical to Figure5.6 a, indicating that addition of quartz (either by fractionation or alteration) is a more importantcontrol on Si variability than fractionation of feldspar.‘3-1Figure 5.5. Pearce element ratio (PER) diagram of (2Ca+Na+K)/Zr PER versus Al/Zr PER forall rhyolite data from the Battle zone in the Buttle Lake mining camp, southwestern BritishColumbia. QP = quartz porphyritic rhyolite (1, least evolved), QFP = quartz feldsparporphyritic rhyolite (2), GQFP = green quartz feldspar porphyritic rhyolite (3, most evolved).Relatively fresh samples are related by feldspar fractionation on this diagram (feldspar line has aslope of 1). Partially metasomatized rocks plot below the feldspar line, but above the sericitealteration line (slope of 1/3). Totally sericitized rocks plot along the sericite alteration line.‘3gO.3QPI-I-W honzon0.25- rhyolite TAnalyticalQFP errorC. A- 0.2- GQFP a AAACC Feldspar fractionation AA A0.15 m=1A ACarbonate AAA+ V.3. AAA4az a,. I AAA0.05- A iA i A m=113ES I Sericite alterationAnalytical error0-—0.05- 1—0.05 0 0.05 0.1 0.15 0.2 0.25 0.3Al/Zr PER (molar)I 39Figure 5.6. Pearce element ratio (PER) bubble plots for all the rhyolite data from the Battle zone,Buttle Lake mining camp, southwestern British Columbia. (a) Plot with bubbles scaled to Si/ZrPER value. Addition of silica is clearly significant in the chert, but not elsewhere. (b) Plot withbubbles scaled to Ca/Zr PER value. In general, calcium is progressively lost as rocks aresericitized, although some of the larger bubbles reflect carbonate alteration (Plate 5 .2c).I LID0.3a: Rhyolite, Si/Zr PER bubbles0 .25•_/ 4AnaIyffcatQFP •_/ error0.2 GQFPXFeldspar fractionation /0.15 m=1Carbonatei.0• EEEz.::::._0.05—0.05 0 0.05 0.1 0.15 0.2 0.25 0.3Al/Zr PER (molar)0.3b: Rhyolite, Ca/Zr PER bubbles_/ TnaiyticaiQFP errorV.0.2ECC Feldspar fractionation0.15 m=1Carbonate°0+ ::.0—0.05—0.05 0 0.05 0.1 0.15 0.2 0.25 0.3Al/Zr PER (molar)iLl’Figure 5.6. Pearce element ratio (PER) diagrams for all the rhyolite data continued.... (c and d)Bubble plots with bubbles scaled to NaJZr PER and K/Zr PER values, respectively. Rocksundergo almost complete loss ofNa upon addition of K and alteration to sericite.lL120.3C: Rhyolite, Na/Zr PER bubbles QP0.25QFV or0.200Feldspar fractionation0.15 m=1 00r..j 0 0Carbonate•0•+ 00A • 0•z 0.I • •b•o 0.05 : • •00 • 0 0 m=1J3£J. Sericite alteraftonAnalytical error0_0.05—0.05 0 0.05 0.1 0.15 0.2 0.25 0.3Al/Zr PER (molar)0.3d: Rhyolite, K/Zr PER bubbles QP/’0.25 •_, 1AnalytlcalQFP o7 error0.2 GQFP./’0Feldspar fractionation0.15 m=100Carbonate6/0.1 A V0.05T00—0.05—0.05 0 0.05 0.1 0.15 0.2 0.25 0.3Al/Zr PER (molar)Figure 5.6. Pearce element ratio (PER) diagrams for all rhyolite data continued.... (e and f)Bubble plots with bubbles scaled to Ba/Zr PER and Rb/Zr PER values, respectively. Barium andrubidium substitute for potassium in sericite, thus they exhibit the same pattern.0.3QP0.25 hnaiyticaiQFP • error0.2 GQFPEcc Feldspar fractionation ..0.15 m=10.1z0.05 .0’—0.05--0.05 0 0.05 0.1 0.15 0.2 0.25 0.3AI,Zr PER (molar)EccLU0z(c’J0.3[ e: Rhyolite, Ba/Zr PER bubblesCarbonate40EZZEEEm = 1i3Sericite alteration0.1 0.15Al/Zr PER (molar)I4Figure 5.6. Pearce element ratio (PER) diagrams for all the rhyolite data continued.... (f) Bubbleplot with bubbles scaled to Mg/Zr PER value. Addition of magnesium reflects incipientchioritization. (g) Bubble plot with bubbles scaled to Fe/Zr PER value. Pyrite stringers anddisseminations in sericite altered rhyolite is marked by addition of iron.1%0.3f: Rhyolite, Mg/Zr PER bubbles Q,/’0.25 tnaiyticaiQFP./ error0.2 GQFPAE Z••Feldspar fractionation /0.15 m=1I%J •Carbonate4—0.05 0 0.05 0.1 0.15 0.2 0.25 0.3Al/Zr PER (molar)0.3f g: Rhyolite, Fe/Zr PER bubbles Q•/Z0.25 / +AnalyticalQFP./ error0.2.CC Feldspar fractionation /‘ •o.is m=1Carbonate •I z: •0 EEEEz.::::.—0.05—0.05 0 0.05 0.1 0.15 0.2 0.25 0.3Al/Zr PER (molar)1415.5 MICROPROBE RESULTSSeveral sericite and one chlorite grain from two thin sections were analyzed to verify thealteration patterns observed from the whole rock geochemical data. The analyses were done byM. Raudsepp at The University ofBritish Columbia, Department of Geological Sciences on afhlly automated Cameca SX-50 microprobe operating in the wavelength dispersive mode with thefollowing conditions: excitation voltage: 15kV; specimen current =20 nA; peak count time =20seconds; background count time = 10 seconds. The following standards and crystals were usedfor Kcc lines: Si phiogopite, TAP; Ti = rutile, PET; Al = grossularite, TAP; Fe = phiogopite,LIF; Mn = spessartine, LW; Mg = phiogopite, TAP; Ca = diopside, PET; Na = albite, TAP; K:phlogopite, PET; Cr = chromite, LW. The Ba Lc line was analyzed on the PET crystal using abarite standard. The analyses are in Tables 5.9 and 5.10. The detection limit for the electronmicroprobe is about 1 wt % for the major elements.Mineral formulae for the average sericite analyses for both the footwall and hangingwallwere recalculated on an anhydrous basis. Sericite from the footwall has the formula:K0 88Na008Ba 01A12(M78Fe05MgSi3 12)010(OH)2. Sericite from the hangingwallhas the formula: K082NaBa003A1(Al78gSi312)0(OH)2.Compared to sericitefrom the footwall, hangingwall sericite has a higher paragonite component. It is also enriched inBa and Mg and does not contain significant Fe. The chlorite analysis (Table 5.9) was notrecalculated because it has a poor total. Chlorite grains, however, are relatively uncommon so theanalysis is retained to illustrate that chlorite in the Battle zone is relatively Mg rich.5.6 SUMMARY AND SPATIAL DISTRIBUTION OF ALTERATIONA map of the alteration zone is shown in Figure 5.7 a to f. Bubbles scaled to the individualelement ratio values (equation B) are plotted against northing and elevation for Section 15+85E.The center of the alteration zone is marked by addition of silica in both the footwall and‘4%immediate hangingwall (Figure 5.7 a), as well as addition of iron in the footwall (Figure 5.7 e).Minerals that correspond to the chemical zonation are quartz and pyrite stringers in the core ofthe footwall alteration zone. A broader zone of sericitization that occurs both above and belowthe orebody (Figure 5.7 c) corresponds to loss ofNa and Ca, and addition of K, Ba (Figure 5.7d) and Rb. Magnesium and Ca, which respectively occur in chlorite and carbonate, do not showany systematic spatial trends (Figures 5.7 f and b).TABLE 5.9 ELECTRON MICROPROBE ANALYSES1OF SERICITE AND CHLORITE IN THE FOOTWALLALTERATION ZONE, PRICE ANDESITE, BATTLE ZONE, BUTI’LE LAKE MINING CAMP,SOUTHWESTERN BRITISH COLUMBIA.MS5..1 MS5-la MS5-4 MSS-7 Average CH5-lMineral Sericite Sericite Sericite Sericite Sericite ChloriteSi02 46.855 45.154 45.603 45.730 45.835 27.061Ti02 0.125 0.148 0.086 0.049 0.102 0.011A1203 34.752 34.785 34.708 35.214 34.865 22.002FeO 1.051 0.983 0.919 0.748 0.925 14.904MnO 0.037 0.048 0.007 0.019 0.028 0.192MgO 0.549 0.651 0.702 0.578 0.62 21.516CaO 0.000 0.000 0.000 0.017 0.004 0.011Na20 0.560 0.676 0.652 0.697 0.646 0.039K20 10.095 10.314 10.219 10.326 10.239 0.055BaO 0.467 0.419 0.502 0.393 0.445 0.018Cr2O3 0.000 0.000 0.000 0.002 0.00 1 0.000Total 94.723 93.376 93.574 93.971 93.911 86.1791 Sample is from DDH 14-906, 303 m or 910 feetTABLE 5.10 ELECTRON MICROPROBE ANALYSES’ OF SERICITE IN THE HANGINGWALLALTERATION ZONE, H-W HORIZON RHYOLITE, BATTLE ZONE, BUflLE LAKE MINING CAMP,SOUTHWESTERN BRITISH COLUMBIA.MS153-1 MS-2 MS-3 MS-4 MS-6 AverageSi02 46.425 46.592 46.819 46.270 46.5 17 46.525Ti02 0.123 0.082 0.083 0.096 0.093 0.095A12O3 34.545 34.875 34.54 35.433 35.715 35.022FeO 0.094 0.040 0.136 0.065 0.057 0.078MnO 0.000 0.000 0.004 0.000 0.000 0.00 1MgO 0.834 0.779 0.926 0.729 0.709 0.795CaO 0.042 0.05 0.007 0.037 0.016 0.03Na20 0.710 0.795 0.693 0.804 0.837 0.768K20 9.495 9.570 9.893 9.415 9.694 9.613BaO 1.201 1.260 0.903 1.459 1.167 1.198Cr2O3 0.000 0.000 0.021 0.006 0.025 0.01Total 93.669 94.245 94.3 10 94.622 95. 100 94.389‘ Sample is from DDH 14-913, 244 m or 734 feetFigure 5.7. Diagram showing the alteration zone for Section 1 5+85E in the Battle zone, ButtleLake mining camp, southwestern British Columbia. (a) Plot with bubbles scaled to Si/Zr PERvalue. Addition of silica is significant in the chert and just below the orebody. (b) Plot withbubbles scaled to Ca/Zr PER value. Ca, present in least altered felsic rocks, is depleted in thealteration zone (Plate 5.2c).10.310.2 I Section 15+85ESi/Zr PER bubbles10.1S• H-Whorizoo.rhyolite10 . 000Co .0 •pproxhnatecontact9.7Price andesite9.6 09.59.413 13.2 13.4 13.6 13.8 14 14.2 14.4 14.6Northing(Thousands)10.310.2 Section10.1•ERbesHW horizon• rhyolite10 ••.0 •:• 0• 0 •pproximate9.7.Price andesite9.609.5.9.413 13.2 13.4 13.6 13.8 14 14.2 14.4 14.6Northing(Thousands)Figure 5.7. Diagram showing the alteration zone for Section 15+85E continued.... (c) Bubbleplot with bubbles scaled to (Al-Na+K)/Zr PER. This diagram illustrates alkali exchange in theBattle zone. (d) Bubble plot with bubbles scaled to Ba/Zr PER values. Ba shows the samedistribution as the alkali exchange plot because Ba is geochemically similar to K.10.310.2 Section 15+85E/ZrPERbubbles10.10H.W horizon10 e rhyolite09.9 Ic(o°989.7Price andesite9.69.513 13.2 13.4 13.6 13.8 14 14.2 14.4 14.6Northin(Thousans)10.310.2 I Section 15-i-85EI Ba/Zr PER bubbles10.1H.W horizon10 8 • rhyolite.0 • •0II9.7,.Price andesite9.69.59.413 13.2 13.4 13.6 13.8 14 14.2 14.4 14.6Northing(Thousands)Figure 5.7. Diagram showing the alteration zone for Section 15+85E continued.... (e) Bubbleplots with bubbles scaled to Fe/Zr PER. Addition of iron is significant just below the orebody. (f)Bubble plots with bubbles scaled to Mg/Zr PER. Large Mg bubbles at the top of the H-Whorizon rhyolite apparently reflect Mg in the “mafic” component of the GQFP; they probably arenot related to hydrothermal activity associated with the ore lens.10.310.2 I Section 15+85EFe/Zr PER bubbles• H-W horizon0• rhyolite100• • 0‘ 9.9 • : • U.• •098_frfi\Poxhnate9.7UPrice andcsite9.6U9.59.413 13.2 13.4 13.6 13.8 14 14.2 14.4 14.6Northing(Thousands)10.310.2 I Section 15+85EMg/Zr PER bubbles10.10 H.W horizon10 • rhyolite•U • •: 0U>zApproximatecontact9.7UPrice andesite9.6 •U9.59.413 13.2 13.4 13.6 13.8 14 14.2 14.4 14.6Northing(Thousands)CHAPTER 6MASSIVE SULPHIDE LENSES IN THE BATTLE GAP AND UPPER ZONES6.1 INTRODUCTIONMassive suiphide lenses in the Battle, Gap and upper zones are a representative subset oflenses that illustrate relationships among mineralized intervals in H-W horizon throughout muchof the Buttle Lake mining camp. The main Battle zone massive sulphide lens occurs at the Priceformation contact, and is stratigraphically correlative to the H-W main lens. The Gap lens alsoappears to have been deposited at the Price formation contact, and may correlate to some of theH-W North lenses (Figure 1.2). Upper zone massive sulphide lenses occur at the contact betweenrhyolite volcaniclastics and overlying rhyolite flows, and are stratigraphically equivalent to someH-W upper zinc lenses (S. Juras, written communication, 1994) and some Ridge zone lenses(Figure 1.2).In the area of the Battle zone, each of the three types of lenses has a distinctive metal andmineral assemblage. Figure 6.1 illustrates the metal assemblage for the different lens types. Themain Battle zone massive suiphide lens is characterized by high copper and zinc compared to lead,whereas the Gap zone has a zinc-lead and minor copper association. Metals in the upper zonelenses are dominantly zinc and lead.The first half of this Chapter characterizes the mineralogy and petrographic characteristicsof the massive sulphides within the Battle, Gap and upper zones. Microprobe data for renieriteand colusite, both from the Gap massive suiphide lens, are also presented. Metal zoning andsuiphide textures within the Battle and Gap zones vary systematically with depth. Aninterpretation for these textures is in section 6.4 where it is suggested that this variation is a resultofprogressive zone replacement (following the processes described by Eldridge et a!. 1983,Ohmoto et a!., 1983 and Fouquet eta!., 1993).6.2 METHODOLOGYAbout 160 polished thin sections and polished sections were prepared from samples ofmassive suiphide collected in the Battle, Gap and upper zones. The main Battle lens was sampledsystematically in Section 15+85E (Figure 3.3), Section 16+92 and Section 17+98E (Figure 3.4).Selected samples were also obtained from Section 13+72E (Figure 3.2) and Section 17+20E.Upper zone samples are from DDH 14-919 (Section 17+98E, Figure 3.4) and 14-723 (Section16+92E). Gap zone samples are from DDH 14-757 (Section 13+72E; Figure 3.2), DDH 14-720(Section 14+02) and DDH 14-713.Assay data for Section 13+72E (Figure 3.2), Section 15+85E (Figure 3.3) and Section17+98E (Figure 3.4) was made available for analysis by Westmin Resources Limited. Thesamples were taken over intervals of 1.5 m or less within the massive sulphide lenses. In the ore,the assay intervals were chosen to represent variations in mineralogical composition -- (e.g.sphalerite rich versus chalcopyrite rich ore). Within the footwall and hangingwall, assay intervalsvaried between 1.5 and 5 m, and boundaries were chosen according to lithology and/or variationsin the amount of suiphide present. The elements Fe, Cu, Pb, Zn, Au and Ag were analyzed for allthe samples; Ba was analyzed for selected samples. Detection limits are 0.05 wt% for the basemetals and barite, and 0.1 grams per tonne for gold and silver.Data from the Battle zone was coded and sorted with respect to lens or the nature of thestockwork. There are three categories of lenses: Battle, Gap and Upper. The stockwork zoneswere classified as either sericite-quartz-pyrite (below the Battle and Gap zones) or polymetallic(below upper zone lenses). Only drill hole 14-757 (Section 13+72E) intersects the Gap lens.IS-)Figure 6.1. Composition of the various lens types in the Battle-Gap zone, Buttle Lake miningcamp, northwestern British Columbia. The main Battle zone massive suiphide lens ischaracterized by high copper and zinc compared to lead, whereas the Gap zone has a zinc-leadand minor copper association. However, only one drill hole intersection through the Gap lens isshown on this plot, therefore, it may not be representative of the Gap lens as a whole. Metals inthe upper zone lenses are dominantly zinc and lead.t5Battle LensCu•..P810A• :•• •%•• ZNGap LensCu*** ********* **PB1O *..** 4 * ZNUpper LensesCuaaaq7aaaP810 00 0 ZNFigure 6.2. Idealized cross-section of the main Battle massive suiphide lens, based on Section13+72E. The massive suiphide lens is zoned from: (i) footwall stockwork mineralization (Plates6.1 a) that is in the Price andesite through, (ii) chalcopyrite rich massive suiphide (Plate 6.2a), (iii)banded massive suiphide mineralization (Plate 6.3a), (iv) pale yellow massive sphalerite at the topand periphery (Plate 6.4a), and (v) bedded massive sulphides locally preserved at the top of theyellow sphalerite zone (Plate 6.5a).LEGENDIdectlizeclmassivesuiphidelensBasedonSection13+72intheBattlezone0BeddedmassivesuiphideYellowmassivesphaleriteBandedmassivesuiphide•ChalcopyriterichmassivesuiphideFootwallstockworkmineralizationPriceandesitePriceandesite051015202550metresIIIII6.2 PETROGRAPHY6.2.1 Main Battle zone massive suiphide lensMineralogy of the main Battle massive sulphide lens is straightforward. In decreasing orderof abundance, the common ore minerals are pyrite, sphalerite, chalcopyrite, tennantite and galena.Gangue minerals are quartz, sericite and rare barite. Fragments of incorporated wall rock arescarce. Much of the main lens is not brecciated or resedimented. It accumulated during a periodof quiescence prior to the eruption of felsic volcanics. The main lens (Figure 6.2) is zonedupwards from: (i) footwall stockwork mineralization (Plate 6.1 a) that is in the Price andesite,through (ii) chalcopyrite rich massive sulphide (Plate 6.2a) at the base of the sulphide lens, (iii)banded massive sulphide mineralization (Plate 6.3a) in the central region, (iv) pale yellow massivesphalerite (Plate 6.4a) at the top and periphery of the lens, and (v) bedded massive sulphide (Plate6.5a) that occurs locally at the top of the yellow sphalerite zone.Metal zoning that follows mineralogical changes is shown in Figure 6.3, a drill hole log ofmetal ratios for DDH 14-920 (Section 17+98). Metals are ratioed against the total base metalcontent. The copper ratio (Cu/[Cu+Zn+Pb]) and zinc ratio (ZnJ[Cu+Zn+Pb]) are antipathetic.That is, high zinc ratios are mirrored by low copper ratios. As expected by the mineralogy, zincratios are high at the top of the massive suiphide lens, and copper ratios are high at the base. Theiron ratio (Fe/[Cu+Zn+Pb]) increases systematically towards the base of the lens, reflectingdominance of pyrite and chalcopyrite. Silver ratios strongly follow lead that occurs in galena atthe top of the lens, and weakly follow copper at the base of the lens, reflecting the presence ofminor silver-rich tennantite. Gold ratios are uniformly low throughout the massive sulphideintersection. This is typical of the main Battle lens that only locally carries gold in excess of 1gram per tonne.I(ZFigure 6.3. Drill hole log of metal ratios for DDH 14-920 in the main Battle massive sulphide lens(Section 17+98). A curve is drawn through the data using the LOWESS smoothing method ofCleveland (1979, 1981). This method produces smoothing by running along the X values andfinding predicted values from a weighted average of nearby Y values. The advantage of thismethod is that it does not presuppose the shape of the function, and may be adjusted to followlocal irregularities. (a) Copper ratio versus depth, and (b) zinc ratio versus depth. The copperand zinc ratios are antipathetic. That is, high zinc ratios are mirrored by low copper ratios. Asexpected by the mineralogy, zinc ratios are high at the top of the massive sulphide lens, andcopper ratios are high at the base. (c) Lead ratio versus depth. The lead ratio is highest at the topof the massive suiphide lens. (d) Iron ratio versus depth. The iron ratio increases systematicallytowards the base of the lens, reflecting the dominance of pyrite and chalcopyrite. (e) Silver ratioversus depth. Silver strongly follows lead that occurs in galena at the top of the lens, and weaklyfollows copper at the base of the lens, reflecting the presence of minor silver rich tennantite. (f)Gold ratio versus depth. Gold is uniformly low throughout the massive sulphide intersection.I H w11.00.20.40.60.81.010000.00.10.20.30.40.50.60.70.8CopperratioZincRatioLeadRatioI H w 070080090070080090010000.0I H uJ 0Cu/(Cu+Zn+Pb)Zn/(Cu÷Zn÷Pb)Pb/(Cu+Zn+Pb)0501001502001000IronRatioSilverRatioGoldRatio700800900I LU 0I 0 LJJ 07008009001000700800900I LU 0100001020304050607080012345678Ba/(Cu+Zn+Pb)Ag/(Cu-fZn+Pb)Au/(Cu+Zn+Pb)Footwall stockwork mineralization comprises a 5 to 30 m thick alteration zone within thePrice andesite immediately below the massive sulphide lens (Figure 6.2). Stockworkmineralization consists of 30 to 50% pyrite ± chalcopyrite-quartz-sericite stringers anddisseminated pyrite in pervasively sericitized Price andesite (Plate 6.1 a). Pyrite in disseminationsand stringers is typically coarse grained and forms porphyroblasts up to 1.5 cm across (Plate6.1 ai). Dihedral angles of 120° degrees between aggregates of pyrite grains indicate extensiveequilibrium recrystallization. Pyrite shapes are euhedral or elongate parallel to the foliation (Plate6.1 a2). Up to 5% chalcopyrite and rare sphalerite occur interstitially to pyrite. Small inclusionsof sphalerite, chalcopyrite or galena, 5 to 30 j.i across, rarely occur within pyrite grains. Quartzcommonly is concentrated in pressure shadows behind pyrite crystals, but it also occurs asdiscrete grains throughout the matrix (Plate 6. 1a3). Sericite within the stringers is coarse grainedand has a first order yellow to second order blue birefringence.Chalcopyrite-rich massive suiphide forms the basal 15 to 25% of the main Battle massivesuiphide lens (Figure 6.2; Plate 6.2a). This facies is particularly well developed close tosynmineral faults (Figure 6.2). The zone typically contains 15% (locally up to 30%) chalcopyriteas anhedral masses intergrown with up to 10% sphalerite and 2% tennantite. These sulphidesoccur interstitial to pyrite porphyroblasts, or as inclusions within the pyrite grains. Morphologyand size of pyrite varies systematically with depth in the pyrite-chalcopyrite zone. Within 2 m ofthe footwall contact, pyrite crystals are porphyroblastic and measure up to 1 cm across (Plate6.2a1). Chalcopyrite, sphalerite or tennantite inclusions in pyrite are rare this close to thefootwall. Above the footwall contact, pyrite occurs as individual to partially coalesced anhedralgrains about 0.5 mm across. Many of the grains enclose large ‘donut hole’ inclusions ofchalcopyrite 30 to 60 j.t across (Plate 6.2a2). Interfacial angles between pyrite grains are generally120°, indicating equilibrium recrystallization. Pyrite in the upper 3 m of the pyrite-chalcopyritezone contains abundant inclusions of chalcopyrite, sphalerite and tennantite (Plate 6.2a3). Minorquartz and lesser sericite are locally intergrown with the sulphides.Banded massive suiphide occur either above the chalcopyrite rich massive suiphide ordirectly above the footwall. It is most common at the western end of the Battle zone, where itcomprises about 40% or a 7 m thickness of the main Battle zone ore body (Figure 6.2 and Plate6.3a). Overall, the modal mineralogy for banded massive suiphide is about 50% sphalerite, 5%chalcopyrite, 25% pyrite, 18% quartz-sericite gangue and less than 2% tennantite. Individualbands are 2 mm to 2 cm thick. The bands are dark silver brown to bright yellow, and consist ofalternating layers of sphalerite-dominant and chalcopyrite-dominant sulphides.Sphalerite-dominant bands are dark brown at the base to yellow-brown at the top andcontain oriented trails of minute chalcopyrite inclusions 1 to 5ji across. Pyrite within thesphalerite-dominant bands has several morphologies (cf Craig and Vaughn, 1981): (i) subhedral,inclusion poor grains, (ii) poikilitic, and (iii) mottled or careous. Subhedral pyrite grains about 0.3mm across occur disseminated throughout the sphalerite. These grains have simple grainboundaries, and locally, porphyroblastically overgrow the sphalerite. Poikilitic pyrite formsslightly larger grains up to 1 mm across (Plate 6.3ai), that incorporate small grains ofchalcopyrite, sphalerite or tennantite less than 20 ji. across. In many grains, the inclusion trailsfollow growth zones in the pyrite crystal. These grains also tend to be scatted randomlythroughout the sphalerite matrix. Careous pyrite, on the other hand, preferentially occurs withchalcopyrite. It occurs in bands subparallel to bedding that follow the minute chalcopyriteinclusion trails (Plate 6.3a2). This type of pyrite has hook shaped protuberances that grow intothe surrounding sphalerite. These growths incorporate large inclusions of sphalerite orchalcopyrite into the center of the pyrite grain (Plate 6.3a2).Chalcopyrite-dominant bands (Plate 6.3a3)contain coarse, anhedral pyrite grains up to 0.5mm across in a chalcopyrite rich matrix (Plate 6.3a4). Pyrite grains within the chalcopyrite bandsare careous or anhedral rather than poikilitic. Any poikilitic pyrite incorporated into the band isrecrystallized to an inclusion-free state. This is shown particularly well on Plate 6.3a5 that showsthe boundary between a sphalerite dominant band (left) and a chalcopyrite dominant band (right).Pyrite within the sphalerite matrix has undergone less recrystallization and contains moremicroinclusions of sphalerite than the pyrite contained within the chalcopyrite matrix. Careouspyrite within the chalcopyrite bands has hook shaped protuberances that enclose large (30 - 6OLL)grains of chalcopyrite (Plate 6.3 a4). In bands thicker than 2 mm, pyrite grains within achalcopyrite-dominant band coalesce to form anhedral masses of pyrite with 2 to 5 large grains ofchalcopyrite enclosed within the mass. Grain boundaries within the pyrite mass approach 1200,indicating equilibrium recrystallization occurred within the band (Plate 6.3a4).Pale yellow massive sphalerite forms the upper 45% or a 4 to 10 m thickness of the mainBattle massive suiphide lens (Figure 6.2 and Plate 6.4a). In some regions, particularly in theupper part of the south trough, this zone is virtually pure sphalerite. Typically, however, theyellow massive sphalerite zone consists of 75% sphalerite, 10% pyrite, 2% tennantite, 1%chalcopyrite and 12% quartz-sericite gangue. Minute, 1 to 5p. inclusions of chalcopyrite occuroriented along planes subparallel to bedding, and as random grains. The origin of the inclusions isdiscussed in section 6.4. Pyrite occurs as: (i) subhedral crystals, or (ii) most commonly aspoikilitic grains. Subhedral pyrite crystals are about 0.2 mm across and occur disseminatedthroughout the sphalerite or in thin laminae. Poikilitic pyrite is typically 0.2 mm across and occursdisseminated throughout the yellow sphalerite zone. Pyrite commonly has a °spongy” lookingwebby core that is rich in microinclusions of sphalerite or chalcopyrite, and an inclusion free rim(Plate 6.4a1). Less spongy looking crystals contain mostly chalcopyrite inclusions.Bedded massive szilphide is preserved only locally in the Battle zone. The sample shown inPlate 6.5 may represent what some of the massive sulphide lenses looked like when firstdeposited. Other sedimentary sulphide textures such as pyritized fauna, framboidal pyrite(Eldridge et al., 1983) or colloidal base metal suiphides (Craig and Vaughn, 1981; Eldridge et al.,1983; Larocque, 1993) are notably absent in the Battle lens.Plate 6.1. Footwall stockwork mineralization, main Battle zone, Buttle Lake mining camp,southwestern British Columbia. Dime is 8 mm in diameter. PY = pyrite. CP = chalcopyrite. GN= galena. SL = sphalerite. (a) Typical sample from the quartz-sericite-pyrite stockwork zone(DDH 14-908, 277 m or 909 feet). (ai) Photomicrograph of porphyroblastic, recrystallized pyritewith very few inclusions (DDH 14-907, 272 m or 891 ft). Chalcopyrite is concentrated alongequant (1200) grain boundaries in pyrite. Such equant grain boundaries represent equilibriumrecrystallization. (a2) Photomicrograph of foliated stringer zone ore (DDH 14-722, 266 m or873 ft). Dark bands are sericite rich and are characterized by elongate grains of inclusion-freepyrite. Quartz rich bands (medium grey matrix) are characterized by equant grains of pyrite withchalcopyrite inclusions. (a3) Photomicrograph of gangue in the footwall stringer zone (DDH 14-906, 277 m or 910 11). Bright birefringent material is coarse grained sericite. The elongate grey-white mineral is quartz; it occurs throughout the matrix.Plate 6.2. Chalcopyrite-rich massive suiphide, main Battle zone, Buttle Lake mining camp,southwestern British Columbia. PY = pyrite. CP = chalcopyrite. GN = galena. SL = sphalerite.TN = tennantite. (a) Chalcopyrite rich ore from the basal 15% of the main Battle massivesulphide lens (DDH 14-75 1, 323.4 m or 1061 feet). Scale is in cm. (a1) Photomicrograph ofpyrite and chalcopyrite (DDH 14-906, 274 m or 900 if). Pyrite grain is pure except for a fewinclusions of chalcopyrite. (a2) Photomicrograph of equilibrium recrystallized pyrite in a matrixof chalcopyrite (DDH 14-729, 321 m or 1055 if). Pyrite grains contain inclusions of chalcopyriteand sphalerite about 30p. across. (a3) Photomicrograph of tennantite occurring as anhedral blobsintergrown with chalcopyrite, pyrite and sphalerite (DDH 14-917, 336 m or 1101 if)./øiLiAvJI’$70Plate 6.3. Banded massive suiphide, main Battle zone, Buttle Lake mining camp, southwesternBritish Columbia. PY = pyrite. CP = chalcopyrite. GN = galena. SL = sphalerite. (a) Bandedpyrite and dark sphalerite (DDH 14-75 1, 321.3 m or 1054 feet). Scale is in cm. (ai)Photomicrograph of poikilitic pyrite in a sphalerite-dominant band (DDH 14-920, 243 m or 798ft). Large inclusions of sphalerite that contained minute inclusions of chalcopyrite were trappedby porphyroblastic pyrite crystals. As crystal growth continued, sphalerite inclusions werepreferentially replaced by pyrite, leaving only chalcopyrite inclusions behind (lower right crystal).(a2) Photomicrograph of careous pyrite in a sphalerite-dominant band (DDH 14-906, 273 m or896 ft). The pyrite grain trapped large sphalerite and chalcopyrite inclusions which are about 60t across. (a3) Chalcopyrite-dominant band (DDH 14-906, 273 m or 896 ft). Pyrite in thesebands tends to be coarser than that in the sphalerite-dominant bands. The pyrite forms masses ofcoalesced careous to subhedral grains with abundant chalcopyrite inclusions. (a4) Close view ofthe edge of the chalcopyrite-dominant band. Note partial replacement of sphalerite inclusions bychalcopyrite. (a5) Near vertical boundary in the centre of the photograph between a sphaleritedominant and a chalcopyrite-dominant band (DDH 14-730, 353 m or 1158 feet). Pyrite grainswithin the chalcopyrite are relatively free of inclusions, and are more intensely recrystallized.Pyrite grains within sphalerite contain abundant inclusions and have a careous, webby texture.The grain marked PY in the center shows a progressive increase in the degree of recrystallizationfrom left to right.I ••1...pY17j- r.I:‘..\?.Ii.•,JI3aIPlate 6.4. Pale yellow massive sphalerite, main Battle zone, Buttle Lake mining camp,southwestern British Columbia. Dime is 8 mm in diameter. PY = pyrite. CP = chalcopyrite.GN galena. SL = sphalerite. (a) Pale yellow sphalerite from the top of the sulphide lens(DDH 14-751, 319 m or 1046 feet). (ai) Euhedral to subhedral spongy looking pyrite grains 80to 250 i across in a matrix of sphalerite (DDH 14-906, 267 m or 877 ft). (a2) Trace of galenaand chalcopyrite in the same sample.Plate 6.5. Bedded massive suiphide, main Battle zone, Buttle Lake mining camp, southwesternBritish Columbia. Scale is in cm. Interbedded sphalerite, pyrite and shale from top of thesuiphide lens (DDH 14-753, 280 m or 920 feet). Bedding to core axis angles in the suiphide unitare the same as in the overlying fine rhyolitic tuffaceous deposits, supporting a sedimentary originfor the layering. Chalcopyrite and galena are concentrated in dewatering pillar structures that arecrudely perpendicular to the bedding.Plate 6.6. Miniature ore deposit (DDH 14-720, 194 m or 634 feet). Scale is in cm. Specimencontains a block-faulted layer at the base, with quartz-filled feeders along the ‘faults’. Mineralzoning is from a pyrite-rich layer at the base to barite-sphalerite mineralization at the top, awayfrom the feeder.-s;_-—-.Ad4•________________1-i LI6.2.2 Gap massive suiphidesThe Gap massive sulphide lens is characterized by a complex mineral assemblage. Mineralsidentified in this study include: pyrite, sphalerite, chalcopyrite, tennantite, galena, bornite, anilite,renierite and colusite. Native gold was observed in hand specimens, but not in any of the polishedsections. Gangue minerals include barite, quartz and lesser sericite. Renierite and colusite wereidentified with the electron microprobe (section 6.2). These two minerals both containgermanium; colusite also contains vanadium. The Gap lens is zoned from: (i) footwall stockworkmineralization (similar to that described in section 6.1.1) that is in both the Price(?) andesite andin the quartz porphyritic rhyolite, upwards through (ii) pyritic massive sulphide, and (iii) bariticmassive sulphide.Metal zoning that follows mineralogical zoning is shown in Figure 6.4, a drill hole log ofmetal ratios for DDH 14-757 (Figure 3.2; Section 13+72). As in the Battle lens, the copper ratio(Cu/{Cu+Zn+Pb]) is high at the base of the lens, the zinc ratio (ZnJ[Cu+Zn+Pb]) is high at thetop, and the two ratios are antipathetic (Figures 6.4a and b). The lead ratio (Pb/[Cu+Zn+Pb]) isslightly elevated at the top of the lens and in the basal half. The barium ratio (BaJ[Cu+Zn+Pb]) ishigh at the top of the lens (Figure 6.4d: upper 18 m or 50 feet), then drops to zero below thebarite-sphalerite blanket. Silver strongly follows copper and reflects the presence of silver richtennantite (Figure 6.40. It does not follow lead as strongly as in the Battle zone (Figure 6.4 c ande). Gold is zoned in the Gap lens, but not in the Battle, and is highest in the copper rich part ofthe massive sulphide lens (Figure 6.4e).Pyritic massive suiphide (Plate 6.7a) forms approximately the lower 60% of the Gapmassive sulphide lens. It consists of about 55% pyrite, 15% sphalerite, 10% tennantite, 5%bornite, 2% galena, 2% chalcopyrite, 1% renierite and colusite, and 1% anilite. The remaining15% is quartz-barite-sericite gangue. Sphalerite, tennantite, chalcopyrite, and bornite aregenerally intergrown together with the gangue minerals (Plates 6.7ai, a and a3). Colusite and175Figure 6.4. Drill hole log of metal ratios for DDH 14-757 in the Gap massive sulphide lens(Section 13+72). A curve is drawn through the data using the LOWESS smoothing method ofCleveland (1979, 1981). (a) Copper ratio versus depth and (b) zinc ratio versus depth. Thecopper and zinc ratios are antipathetic. That is, high zinc ratios are mirrored by low copperratios. As expected by the mineralogy, zinc ratios are high at the top of the massive suiphide lens,and copper ratios are high at the base. (c) Lead ratio versus depth. The lead ratio is high at thetop and the base of the massive sulphide lens. (d) Barium ratio versus depth. The barium ratiodrops to 0 below the barite-sphalerite blanket at 213 m or 700 feet depth. (e) Silver ratio versusdepth. Silver strongly follows copper at the base of the lens, reflecting the presence of silver-richtennantite. (f) Gold ratio versus depth. Gold follows copper rich mineralization.I D.LUCopperRatioZincRatioLeadRatioIII6007008000•I F— 0 UJ 0600700800-900 0.00.20.40.60.81.0I I— 0 w 0600700800900 0.00.10.20.30,4900 0.00.20.40.60.81.0IICu/(Cu+Zn+Pb)Zr,/(Cu+Zn+Pb)Pb/(Cu+Zn÷Pb)600BariumRatio600SilverRatio600GoldRatioa- LU 0-101LU 090001020304050I I a w 090070080090070080070080020123Ba/(Cu+Zn+Pb)Ag/(Cu+Zn+Pb)Au/(Cu+Zn+Pb)Plate 6.7 Pyritic massive suiphide, Gap zone, Buttle Lake mining camp, southwestern BritishColumbia. Scale is in cm. PY = pyrite. CP = chalcopyrite. GN = galena. SL = sphalerite. TN =tennantite. CC = anilite. CO = colusite. RN = reneirite. (a) Hand specimen of pyritic massivesuiphide (DDH 14-757, 224 m or 734 feet). Sample contains pyrite, sphalerite, bornite, andanilite. (a1) Photomicrograph of a fine-grained pyrite mass in a matrix of bornite, chalcopyrite,tennantite, and sphalerite (DDH 14-720, 202 m or 664 ft). Colusite occurs as tiny round blobsabout 5.t across in bornite (to the left). (a2) Photomicrograph of galena ‘fan’ rimmed by borniteand sphalerite (DDH 14-720, 208 m or 683 ft). (a3) Photomicrograph of fine grained pyritemasses and idiomorphic pyrite in a matrix of bornite, galena, tennantite and sphalerite (DDH 14-720, 208 m or 683 ft). (a4) Photomicrograph of poikilitic, euhedral pyrite with tiny, 5i.tinclusions of colusite in a matrix of bornite, galena, tennantite and sphalerite (DDH 14-7 17, 194m or 637 ft). Colusite inclusions also occur in the sphalerite. Blue areas are anilite. (a5)Photomicrograph of tiny 5-lOi.t inclusions of renierite and colusite in a matrix of bornite andsphalerite (DDH 14-7 17, 194 m or 637 ft). (a6) Photomicrograph of intergrown sphalerite,bomite and tennantite (DDH 14-720, 202 m or 664 ft). Abundant Si.i. blobs of colusite havegrown on the central bornite blob. (a7) Photomicrograph of anilite myrmekitically intergrownwith galena (DDH 14-720, 208 m or 683 fi).-‘Sa7’1v:‘7ScPlate 6.8 Baritic massive suiphide Gap zone, Buttle Lake mining camp, southwestern BritishColumbia. Scale is in cm. PY = pyrite. GN = galena. SL = sphalerite. BA = barite. QZ =quartz. TN = tennantite. (a) Hand specimen from the upper part of the Gap lens (DDH 14-757,200 m or 656 feet). This sample contains sphalerite, barite, pyrite, quartz, galena and tennantite.Barite in centre shows convex surfaces that face up-hole (to the right). (al) Photomicrograph ofbarite and quartz gangue (DDH 14-757, 200 m or 656 feet). (a2) Photomicrograph of careouspyrite in sphalerite (DDH 14-757, 205 m or 672 feet). (a3) Photomicrograph of porphyroblasticpyrite with large inclusions of galena, tetrahedrite and sphalerite (DDH 14-757, 200 m or 656feet).Plate 6.9 Upper zone massive suiphide, Battle zone, Buttle Lake mining camp, southwesternBritish Columbia. Scale is in cm. PY = pyrite. GN = galena. SL = sphalerite. CP = chalcopyrite.TN = tennantite. (a) Polymetallic stringers in tuffaceous sandstone (DDH 14-750, 260 m or 854feet). Relict sedimentary bedding is still visible. (ai) Photomicrograph of a polymetallic stringer(DDH 14-750, 260 m or 854 feet) containing galena, chalcopyrite, sphalerite, tennantite andsubhedral pyrite. (b) Hand specimen from an upper zone massive sulphide lens (DDH 14-723,218 m or 715 feet). Specimen contains sphalerite, tennantite, pyrite, galena and chalcopyrite.(b1)Photomicrograph of the sulphide assemblage in an upper zone massive sulphide lens (DDH14-723, 218 m or 715 feet). Tennantite, pyrite and sphalerite occur in equal proportions withlesser galena.8a18a1IiiI ?1GNlOOjirenierite occur as small inclusions in other suiphides, but particularly in sphalerite or bomite(Plates 6.7a4, a and a6). Renierite may be distinguished from bornite by its reddish orangecolour and distinct anisotropy. It also does not tarnish readily when exposed to air. Colusite ispale tan and isotropic. It is harder than bornite, but slightly softer than tennantite. Anilite occurswith bornite, chalcopyrite or tennantite, and rarely as myrmekitic intergrowths with galena (Plate6.7a7). Pyrite has two habits: (i) large, poikilitic grains (about 250 t across) with abundantinclusions of other suiphides (Plate 6.7a4), and (ii) small, inclusion-free grains (about 50 j.t across:Plates 6.7ai and a3). The small grains mostly coalesce to form complex pyrite aggregates withother sulphides trapped in the interstices.Baritic massive suiphide (Plate 6.8a) consists of 20% barite, 50% sphalerite, 10% pyrite,2% chalcopyrite, 5% galena, 6% tennantite and 7% quartz + sericite. Barite forms long tabularcrystals intergrown with quartz and other sulphides (Plate 6.8ai). Pyrite occurs as anhedralmasses or as careous grains that enclose large inclusions of other sulphides (Plates 6. 8a2 and a3).Sphalerite, tennantite, galena and chalcopyrite occur together as anhedral masses. Mutual grainboundaries between these suiphides display a minimum of interlocking. Chalcopyrite also occursas minute 1 to 5ji inclusions in sphalerite.6.2.3 Upper zone massive suiphidesUpper zone massive sulphide lenses are mostly at the contact between rhyolitic tuffaceoussediments and the quartz-feldspar porphyritic flow. They are zoned from a polymetallic stringerzone in the footwall (Plates 6.9a and a1) to a suiphide rich assemblage at the base (Plates 6.9b andb1) and locally a barite-sphalerite blanket. Suiphides consist of 30% pyrite, 30% tennantite, 30%sphalerite, 4% galena and 1% chalcopyrite. Pyrite generally forms euhedral to anhedralporphyroblasts. The other sulphides typically are intergrown. Gangue minerals intergrown withthe suiphides are barite, quartz and lesser sericite.6.3 MICROPROBE RESULTSRenierite and colusite were identified with the electron microprobe at The Department ofGeological Sciences, The University of British Columbia. Sphalerite, bornite and anilite grains onthe same slides were also analyzed. The analyses were done by M. Raudsepp on a fillyautomated Cameca SX-50 microprobe operating in the wavelength dispersive mode with thefollowing conditions: excitation voltage = 20kV; specimen current = 30 nA; peak count time =20 seconds; background count time = 10 seconds. The following standards and crystals wereused for Kx lines: Cu = tetrahedrite, LW (lithium fluoride); Fe = pyrrhotite, LW; V = vanadiummetal, LW; Zn = tetrahedrite, LW; Ge = germanium metal, LW; Sb = tetrahedrite, PET; S =pyrrhotite, PET. Arsenic was measured against a tennantite standard using the La line and theTAP crystal. The beam diameter was 1I.TABLE 6.1 MICROPROBE ANALYSES FOR RENIERITE, GAP ZON& MASSIVE SULPHIDE LENSM3-1 M3-2 M3-3 M2-1 M2-2 AverageWeight %Cu 42.830 42.218 42.350 42.307 42.396 42.42Zn 1.365 1.404 2.226 0.921 0.904 1.364Ge 6.201 6.265 5.575 5.652 5.549 5.848As 2.863 2.721 3.180 3.362 3.232 3.072Sb 0.292 0.202 0.240 0.24 1 0.228 0.24 1V 0.115 0.091 0.128 0.100 0.100 0.107Fe 14.161 14.136 13.625 13.972 13.741 13.927S 31.773 32.334 32.368 32.554 32.433 32.292Total 99.599 99.3 71 99.694 99.109 98.584Mole %Cu 32.60 32.04 32.08 32.13 32.36 32.24Zn 1.01 1.04 1.64 0.68 0.67 1.01Ge 4.13 4.16 3.70 3.76 3.71 3.89As 1.85 1.75 2.04 2.17 2.09 1.98Sb 0.12 0.08 0.10 0.10 0.09 0.1V 0.11 0.09 0.12 0.09 0.09 0.1Fe 12.26 12.21 11.74 12.07 11.93 12.04S 47.92 48.63 48.59 49.00 49.05 48.64# ofAtomsCu 10.76 10.57 10.59 10.61 10.68 10.64Zn 0.33 0.34 0.54 0.22 0.22 0.33Ge 1.36 1.37 1.22 1.24 1.22 1.28As 0.61 0.58 0.67 0.72 0.69 0.65Sb na na na na na naV na na na na ná naFe 4.05 4.03 3.87 3.98 3.93 3.97S 15.81 16.05 16.04 16.17 16.19 16.051 Sample is from DDH 14-717, 212 mTABLE 6.2 MICROPROBE ANALYSES FOR COLUSITE, GAP ZONE MASSIVE SULPHIDE LENSCl1 C2’ C31 C4’ C51 M3 ...42 Ml 22 AverageWeight %Cu 49.285 49.135 49. 156 47. 145 49.057 48.243 47.255 48.468Zn 1.423 1.102 1.470 3.947 1.779 1.640 2.567 1.99Fe 0.568 0.805 0.687 0.638 0.423 2.572 2.320 1.145V 3.180 3.008 3.075 3.014 3.211 2.101 2.096 2.812Ge 5.566 5.316 5.209 5.899 5.226 7.158 7.220 5.942As 7.607 7.677 7.728 7.281 7.934 5.964 5.639 7.119Sb 0.078 0.121 0.141 0.084 0.118 0.355 0.291 0.108S 32.066 32.041 32.141 31.832 31.631 31.680 31.811 31.886Total 99. 773 99.115 99.607 99.840 99.3 79 99. 713 99.289Mole %Cu 37.86 37.94 37.79 36.28 37.93 37.20 36.532 37.362Zn 1.06 0.76 1.10 2.95 1.34 1.23 2.00 1.49Fe 0.50 0.71 0.60 0.56 0.37 2.26 2.04 1.01V 3.05 2.90 2.95 2.89 3.10 2.02 2.02 2.7Ge 3.74 3.59 3.51 3.97 3.54 4.83 4.88 4.01As 4.96 5.03 5.04 4.75 5.20 3.90 3.70 4.65Sb 0.03 0.05 0.06 0.03 0.05 0.14 0.12 0.07S 48.81 49.03 48.96 48.55 48.47 48.41 48.72 48.71# AtomsCu 12.49 12.52 12.47 11.97 12.52 12.28 12.06 12.33Zn 0.35 0.25 0.36 0.97 0.44 0.41 0.66 0.49Fe 0.17 0.23 0.20 0.18 0.12 0.75 0.67 0.33V 1.01 0.96 0.97 0.95 1.02 0.67 0.67 0.89Ge 1.23 1.18 1.16 1.31 1.17 1.59 1.61 1.32As 1.64 1.66 1.66 1.57 1.72 1.29 1.22 1.54Sb 0.01 0.02 0.02 0.01 0.02 0.05 0.04 0.02S 16.10 16.18 16.16 16.02 16.00 16.00 16.1 16.08‘Sample is from DDH 14-720; 221 m.2 Sample is from DDH 14-717; 212 mdiameter used was 1 m. Results from the renierite and colusite analyses are in Tables 6.1 and6.2.Renierite and colusite are members of the germanite group of minerals. Renierite was firstidentified at Kipushi, Zaire where it was named “orange bornite” (Vaes, 1948). The mineral hassubsequently been found in other Cu-Zn-Pb ores throughout the world; a table of localities is inBernstein (1986). Most occurrences are in dolomite hosted deposits, although one otheroccurrence in massive sulphide mineralization was documented at the Shakanai mine in theKuroko district of Japan (Miyazaki eta!., 1978). Renierite is commonly associated with bornite,tennantite, chalcopyrite, galena, chalcocite and pyrite.‘5A general formula for renierite isCui0(ZniCu)Ge2AsFe4Si6,with continuous solidsolution between the zincian and arsenian endmembers Cu 10ZnGe2Fe4S16 andCu1GeAsFe4S16(Bernstein, 1986). Renierite in the Gap zone has the formulaCu10(Zn033064)(Ge1.3As07)Fe4S16 This is similar to arsenian renierite from Shakanai (Miyazaki et a!.,1978), Inexco #1, Jamestown Colorado (Lowe, 1975; Jenkins, 1975; Bernstein, 1986) and theRuby Creek deposit, Alaska (Bernstein, 1986). The arsenian variety is reddish compared tozincian renierite and is characteristic of Cu- and As-rich polymetallic deposits.Colusite is a rare sulfide of copper, vanadium, arsenic and tin. It was first described inButte, Montana (Landon and Molignor, 1933). Other localities are Chizeuil, Saône-et-Loire,France (Picot et a!., 1963); Chelopech, Bulgaria (Terziev, 1966); Carrarra, Italy (Orlandi eta!.,1981) and the Gay copper-zinc deposit in the southern Urals (Pshenichnyi eta!., 1974).An ideal formula for colusite is Cu13V(As,Sn)S16(Orlandi et at., 1981: normalized to 33atoms). Vanadium is an essential component, although some iron may be accommodated in the Vsite. Most substitution occurs in the (As, Sn) site, which may contain iron, germanium orantimony. Colusite in the Gap massive suiphide lens is compositionally similar to colusite fromGay (Pshenichnyi eta!., 1974), and has the formulaCu123Zn05Fe)(V91)(Ge 3As15Sb02)S16.1Additional minerals associated with the renierite and colusite samples were also analyzedwith the electron microprobe (Appendix B). Pale blue ‘chalcocit& has 7 copper atoms for every 4sulphur atoms, or the formula Cu7S4. The name for this mineral is anilite (Table B. 1), a memberof the chalcocite (Cu2S) group which also includes geerite (Cu8S5),digenite (Cu9S5),yarrowite(Cu9S8)spionkopite (Cu39S28),and covellite (CuS). Bornite from the Gap is stoichiometric(ideal bornite = Cu5FeS4)within analytical error (±0.1 wt%). Two sphalerite analyses arealmost iron-free, but contain up 0.5 wt% Cu (Table B. 1).6.4 INTERPRETATION OF SULPHIDE TEXTURES6.4.1 Descriptive interpretationThe main Battle massive suiphide lens displays a number of consistent mineralogical andtextural trends with depth to the footwall (Figure 6.4). These include: (i) well developed zoningfrom Zn to Fe-Cu to Fe sulphides, (ii) decrease in the number of inclusions in pyrite, and (iii) anincrease in grain size. The observed metal zoning is typical of VMS type deposits (Sangster,1972; Sato, 1972; Large, 1977; Solomon and Walshe, 1979; Franklin et a!., 1981; Eldridge et a!.,1983; Huston and Large, 1989). Similar textural zoning trends in the sulphide minerals have beendocumented for the Kuroko deposits by Eldridge eta!., (1983); the textures were attributed to asustained period of fluid circulation within the mound itself as it formed at the sea floor. Theprocess described by Eldridge et. al (1983) was modeled thermodynamically by Ohmoto et a!.(1983), and is referred to here as progressive zone replacement.Progressive zone replacement occurs during a period when hot fluids from below wereconformably and progressively in contact with previously deposited sulphides (facies 1 sulphide ofEldridge eta!., 1983). Early deposited minerals are thus replaced and/or recrystallized inresponse to introduction of new fluid (facies 2 sulphide of Eldridge eta!., 1983). Consequently,the fluid changes composition as it moves upward. The Battle zone offers a superb opportunityto study the sulphide textures produced during progressive zone replacement because the massivesuiphide lens is not significantly folded or otherwise tectonically disrupted. Resedimentation ofthe lens is also minimal, so the zones are in situ (see Figure 6.2).The top of the suiphide lens is locally overlain by bedded massive sulphide (Figure 6.5a andPlate 6.5) that most closely represents what the lens could have looked like prior to progressivezone replacement. These bedded sulphides are probably not texturally representative of what themound looked like when it wasfirst deposited. Rather, they represent the last exhalations ofremobilized metals (mostly zinc) from within the mound prior to burial. The ore is very finegrained, and interlaminated with grey shaly sediments. The paucity of galena and barite in this unitmost likely reflects the low concentrations of these elements in the hydrothermal solutions. Thisunit would be equivalent to the facies 1 sulphide of Eldridge eta!. (1983) that contains finegrained and often colloform sphalerite, galena, pyrite, tetrahedrite and barite, with minorchalcopyrite and quartz. Bedded massive suiphide does not contain colloform sulphides orframboidal pyrite, however, such primary sedimentary textures may well have been presentelsewhere prior to progressive zone replacement throughout the rest of the massive suiphide lens.Yellow massive sphalerite contains two texturally significant features: (i) abundant microinclusions of chalcopyrite, about 1 to 5j.t across, concentrated along bands that are subparallel tobedding, and (ii) 5-10% web textured poikilitic pyrite containing inclusions of sphalerite (Figure6.5b). The origin of chalcopyrite inclusions in sphalerite may be due to one of three processes(Bortnikov et a!., 1991): (i) exsolution of chalcopyrite from sphalerite, (ii) replacement ofsphalerite by chalcopyrite, and (iii) coprecipitation of sphalerite and chalcopyrite. Thereplacement origin is favoured here because the inclusions are preferentially concentrated alongbands; deeper into the sulphide mound these inclusion bands coalesce and form wider bands ofchalcopyrite that clearly have a replacement origin (see next paragraph). Poikilitic pyrite is also ofreplacement origin. Crystals grow by adding material at the periphery. Because pyrite grew whilesphalerite did not, pyrite simply overgrew the sphalerite. The result of this process is abundantpyrite crystals, each with a small cloud of sphalerite blebs in their centre, but none in their rims(cf Eldridge eta!., 1983).Sphalerite dominant bands in the banded massive sulphide contain suiphide with texturessimilar to those described above for the yellow massive sphalerite. Poikilitic pyrite is common,but tends to be coarser grained (Figure 6.5c; Plates 6.4a1 and 6.3ai). Careous pyrite is alsosignificant in sphalerite dominant bands. Careous growths are hook shaped protuberances ofpyrite that grow into the surrounding sphalerite. These growths incorporate large inclusions ofsphalerite into the center of the pyrite grain. Plate 6.3a2 shows both a partially incorporated and aflilly incorporated grain of sphalerite. Careous pyrite grains tend to occur in submicroscopicFigure 6.5 Idealized progressive recrystallization textures observed in the main Battle zonemassive suiphide lens. Many of these textures are also present in the Gap zone. (a) Beddedmassive sulphide most closely represents what exhalative ore may have looked like when it wasfirst deposited (Plate 6.5). Thin bedding in the sulphide is due to sedimentary processes becausethe orientation of the bedding in the suiphides matches the orientation of the bedding in theoverlying shale. The pillar structure is most likely a dewatering feature. Sulphides within the unitare dominantly yellow sphalerite with lesser pyrite and galena. (b) Pale yellow massive sphaleritewith characteristic minute chalcopyrite inclusions and web textured poikilitic pyrite (Plate 6.4).The chalcopyrite inclusions are preferentially oriented parallel to bedding. poikilitic pyrite withspongy looking cores fhll of sphalerite inclusions and inclusion free rims reflects incipient growthof pyrite around a fine grained pyrite + sphalerite substrate. (c) Banded massive sulphide.Sphalerite dominant bands contain poikilitic pyrite and bedding parallel bands of careous pyriteassociated with chalcopyrite (Plate 6.3). Pyrite within the sphalerite is poikilitic, but that withinthe chalcopyrite band is subhedral or careous. Careous growths often entrap large inclusions ofchalcopyrite within the pyrite. The pyrite grain on the chalcopyrite-sphalerite boundary illustratesthat pyrite in contact with chalcopyrite is recrystallized, whereas pyrite within the sphalerite is stillpoikilitic. (d) Chalcopyrite rich massive suiphide (Plate 6.2). Careous pyrite is still present, butmost pyrite has crystallized to arihedral grains with large inclusions of chalcopyrite. Grainboundaries between pyrite grains in contact are close to 1200. (e) Footwall stockworkmineralization (Plate 6.1). Pyrite is free of inclusions and recrystallized to porphyroblastic,euhedral grains. Grains in sericite rich bands are foliated.BEDDEDMASSWESULPHIDEPALEYELLOWMASSPESPHALERIIEBANDEDMASSVESULPHIDEDewoteringpillarstructure Thinlybeddedshale—cPThinlybeddedsulphidesandshale1cmSLSL 0Minutechalcopyrite0•00inclusions0 0.1mmII1mm_EZ_FoliatedinclusionfreepyriteSericitelayer.._—________.____flowFluidshadowQuartzinpressureCholcopyritemobilizedtoequilibrium_______boundariesII5mm•000SphaleriteSLPoikioliticdominantbandpyrite SLSLCHALCOPYRITERICHMASSIVESULPHIDE0•000MostlyinclusionfreepyriteporphyroblastsFOOTWALLSphaleritedominantbandII5mmJt;to occur in submicroscopic bands subparallel to bedding (as defined in the overlying volcanics). Italso preferentially occurs with chalcopyrite (Plate 6.3a2). The relationship of careous pyrite tochalcopyrite and the orientation of the bands suggests that additional chalcopyrite and latercareous pyrite grew preferentially around the pre-existing (and enlarged) minute chalcopyriteblebs. Chalcopyrite dominant bands form when enough additional pyrite and chalcopyrite isadded to make the bands macroscopic (2 mm to 2 cm thick). Pyrite grains within the chalcopyritebands are invariably careous rather than poikilitic. Any poikilitic pyrite incorporated into theband is recrystallized to an inclusion-free or careous state. This is shown particularly well onPlate 6.3a5 (and interpretively drawn on Figure 6.5c) where a chalcopyrite-dominant bandincorporated part of a pre-existing poikilitic pyrite grain. The half of the pyrite grain that is stillin the sphalerite matrix contains abundant minute inclusions of sphalerite (and galena). The halfthat has been incorporated into the chalcopyrite band is free of inclusions. Note also in this platethat galena is concentrated along the boundary between the chalcopyrite dominant and thesphalerite dominant band. The implication is that any lead present is being remobilized by theinvasion of cupiferous mineralizing fluids.Chalcopyrite rich massive sulphide is characterized by subhedral pyrite grains with largeinclusions of chalcopyrite. Careous pyrite is less common in this zone than in the overlyingbanded massive sulphides because recrystallization is more complete, and careous growths havetotally included masses of chalcopyrite within growing pyrite grains. Where individual pyritegrains have coalesced to form anhedral pyrite masses, the interfacial angles between pyrite grainsapproach 1200 (Figure 6.5d and Plate 6.2a2). Equant grain boundaries are indicative ofequilibrium recrystallization. Poikilitic pyrite is absent as it would have all been recrystallized toinclusion-free subhedral pyrite.Footwall stockwork mineralization consists primarily of equilibrium recrystallized pyrite andquartz-sericite gangue (Figure 6.5e). Chalcopyrite has mostly migrated to pyrite grainboundaries, very few inclusions of other sulphides remain in the pyrite.il I6.4.2 Progressive Zone Replacement: A Textural InterpretationThe morphology of pyrite and chalcopyrite visually indexes the degree that progressivezone replacement has occurred. Those textures considered to be important in the Battle zone areinterpreted, below, following four stages of zone replacement and lens growth outlined inEldridge eta!. (1983) and corroborated by Fouquet eta!., (1993).Fine grained, facies 1 “black ore” was formed from early stage hydrothermal fluids.Massive sulphides in the Battle zone contain only minor galena and barite, therefore the original“black ore” must have been sphalerite and pyrite with lesser copper and lead sulphides. Thebedded massive suiphide (Figure 6.5a) most closely represents facies 1 sulphide.With increasing temperature, leaching of minerals in the previously formed suiphide mudbegan. Fluids acquired Zn, Pb and minor Cu and moved upwards through the ore zone. Thesefluids precipitated facies 2 sulphide within, and facies 1 sulphide on top of the sulphide pile.Trails of minute chalcopyrite inclusions and poikilitic pyrite in yellow massive sphalerite mark theinitial replacement of pre-existing sphalerite by Fe-Cu suiphides. (Figure 6. 5b)As the temperature increased, Cu rich solutions invaded the base of the ore lens. If thefluids were undersaturated with respect to all ore minerals except pyrite and quartz (Ohmoto etal., 1983), the fluids would dissolve available sphalerite and minor galena and release H2S. TheH2S would react with Cu to precipitate chalcopyrite. In the Battle zone, remobilization of galenais particularly apparent in Plate 6.3a4 Dissolution and replacement of sphalerite continued alongthe trails marked by chalcopyrite blebs. This is initially expressed as trails of isolated grains ofpyrite growing around large inclusions of chalcopyrite and sphalerite (Plate 6.3a2). As zonereplacement progressed, the pyrite/chalcopyrite grain trails grew into macroscopic bands ofchalcopyrite and careous pyrite (Figure 6.5c) characteristic of banded massive suiphide. Oncemost of the sphalerite was gone, the ore was transformed into chalcopyrite rich massive suiphide(Figure 6.5d). At this stage, most of the small sulphide inclusions that were contained in pyriteare gone, and grain boundaries between neighboring pyrite grains approached 1200.Once most of the sphalerite and galena were dissolved, chalcopyrite started to dissolve butpyrite continued to precipitate because the solutions were undersaturated with respect toeverything except quartz and pyrite. Inclusion free pyrite with equant grain boundaries indicativeof equilibrium recrystallization dominates the base of the massive suiphide lens and the immediatefootwall (Figure 6.5e).3CHAPTER 7.GALENA LEAD ISOTOPES, BUTTLE LAKE MINING CAMP7.1 INTRODUCTIONGalena was sampled from 18 massive sulphide lenses in the H-W horizon and the Lynx-Myra-Price horizon in the Buttle Lake mining camp. The locations of the samples are on Figures7.1 and 7.2. Table 7.1 presents 103 lead isotope analyses of 53 galena samples from the 18lenses. Twenty-three of these samples are from the Battle and Gap zone. These were collectedby the author and were analyzed during this study. Thirty galena samples from the rest of thecamp were collected and analyzed during earlier research by C. I. Godwin and S. J. Juras (writtencommunication, 1993). S. J. Juras provided much of the geological information on the lensesoutside of the Battle and Gap zones (personal and written communication, 1993, 1994). Andrew(1987), and Andrew and Godwin, (1989) noted that galena from the Myra ore deposit had206Pb/4 and 208Pb/4 isotopic ratios that were statistically different from the H-Wdeposit. Their conclusion was that the galena lead might be useful in distinguishing andcorrelating ore lenses. They also noted that Sicker Group lead isotope ratios of galena and wholerock are typical of those from island arcs. Work presented here extends previous studies.In the following, the overall plumbotectonic ‘orogene’ or island arc character of the galenalead isotopes is first established for massive sulphide mineralization in the Buttle Lake miningcamp. A statistical analysis of data from all samples shows that it can be divided into threeclusters (albeit one cluster is a single point) along an apparent mixing line. Two lead isotopemodels are presented to explain the mixing line. It is argued that: (i) the end-member representingthe most radiogenic galena lead represents either lead selectively leached from the volcanic rocksor lead from andesite with a different isotope composition, and (ii) the other, less radiogenic endmember represents lead magmatically derived, and/or possibly leached, from dominantly rhyoliticTABLE7.1.GALENALEADISOTOPEDATA1FOROREBODIESINTHEBUTLELAKEMININGCAMP,CENTRALVANCOUVERISLAND,SOUTHWESTERNBRITISHCOLUMBIALABNORUNSLENSHORIZONCODE206Pb4207P1J4b208Pb”4b7W6bx208Pb”6b100xlOCluster130735-018N=2Oreclast brecciaORE-XX18.44815.56438.08784.37120.647Cluster230316-001N=2GapH-WG18.48315.56738.10084.22220.61430316-002N=2GapH-W018.48515.57338.12184.25220.62430316-003N=1GapH-W018.49515.57738.14584.23020.62730316-004N=1GapH-WG18.47915.57738.12784.29520.63331145-016N=1GapH-WG18.49015.57938.14584.25220.63030735-009N=1I-I-V.’:BorniteH-WN18.50815.57038.12684.12320.60030735-206N=2H-W:BorniteH-WN18.47615.56738.10084.25120.62030735-207N=5H-W:BorniteH-WN18.50415.57438.11684.16020.61130735-219N=2H-W:BorniteH-WN18.49315.57538.12984.21820.61730735-220N=2H-W:BorniteH-WN18.48015.56038.08584.19920.60831145-002N=1Battle: UpperH-WU18.49115.57038.12584.20520.61831145-003N=1Battle: UpperH-WU18.51515.57238.14484.10720.60231145-006N=3Battle: UpperH-WU18.50115.58138.15384.21620.62231145-010N=1Battle:UpperH-WU18.49115.56738.11184.18620.61031145-011N=1Battle: UpperH-WU18.51315.58038.16184.16020.61431145-012N=1Battle:UpperH-WU18.50915.58738.17184.21220.62331145-014N=1Battle: UpperH-WU18.48915.57538.13484.24120.62631145-015N=1Battle: UpperH-WU18.49815.57538.18084.19820.61331145-013N=1Battle:UpperH-WU18.50415.58038.15384.19920.61930735-004N=1H-W:UpperZincH-WA18.51115.57638.14684.14520.60831145-018N=1Battle: MainH-WB18.51015.57538.14584.14420.60831145-017N=1Battle: MainH-WB18.50615.57038.13084.13420.60431145-019N=1Battle: MainH-WB18.49915.56338.10484.12920.59831145-003N=1Battle: MainH-WB18.51515.57238.14484.10720.60230443-216N=2Lynx:HORE-XH18.51615.57938.16484.13420.61130443-217N=2Lynx:IORE-XI18.50115.57438.14284.18320.616IAllanalyses weredonebyA.Pickering,GeochronometiyLaboratory,Department ofGeological Sciences, TheUniversityofBritishColumbia.TABLE7.1.GALENALEADISOTOPEDATA1FOROREBODIESINTHEBUTfLELAKEMINTNGCAMP:CONTINUED....LABNORUNSLENSHORIZONCODE206PW4b207PW4b208P1J4b207P1J6b2op1JOp1flfl30703-001N1MyraL-M-P/ORE-XY18.49315.56538.10484.16920.60530703-002N1MyraL-M-P/ORE-XY18.48915.56838.11384.20120.61430703-202N=3MyraL-M-P/ORE-XY18.48615.54938.06784. 12020.59430703-203N=3MyraL-M-P/ORE-XY18.49215.55938.09184.13920.59830703-204N=2MyraL-M-P/ORE-XY18.49915.56838.11884.15520.60530703-201N1MyraL-M-P/ORE-XY18.51615.57138.13584.09920.596Cluster331145-005N=1Battle:MainH-WB18.57515.57838.20083.86820.56631145-007N=1Battle:MainH-WB18.53015.57438.15184.04820.58931145-008N’lBattle:MainH-WB18.54115.58038.17584.03320.59031145-001N=2Battle:MainH-WB18.52515.56738.13584.03020.58631145-009N=1Battle:MainH-WB18.58615.59038.24083.88420.57530735-008N=3H-WNorthH-WK18.56615.57438.17883.88820.56530735-015N=1H-W:UpperZincH-WC18.53715.57538.15784.02020.58430735-217N3H-W:UpperZincH-WD18.53315.57238.14784.02720.58430735-005N=2H-W:MainH-WM18.56215.58938.21583.98420.58730735-202N=2H-W:MainH-WM18.55315.57738.17183.96020.57430735-224N=3H-W:MainH-WM18.55715.56738.15283.88820.55930735-007N2RidgeWestH-W?R18.55415.58238.19583.98320.58630443-008N=2Lynx:SL-M-PS18.57315.58238.20383.89520.56830443-208N=3Lynx:SL-M-PS18.54015.56438.13583.95020.56930443-209N=3Lynx:SL-M-PS18.55615.56838.14783.88920.55830443-006N=2Lynx:WestG(W)L-M-PW18.55215.57738.17283.96420.57630443-201N2Lynx:WestG(V)L-M-PV18.54815.57438.15883.96520.57430443-203N=2Lynx:WestG(V)L-M-PV18.54915.57538. 16283.96520.57430443-204N=12Lynx:WestG(W)L-M-PW18.56315.57238.17083.88720.56230360-001N3PriceL-M-PP18.53415.56838.14084.00020.5801 AllanalysesweredonebyA.Pickering,GeochronometryLaboratory,Departmentof GeologicalSciences, TheUniversityofBritishColumbia.(7’19Figure 7.1. Buttle Lake mining camp, central Vancouver Island, southwestern British Columbia(inset), showing the surface and vertical projections of the ore lenses analyzed in Table 7.1(Westmin Resources Limited Annual Report, 1992). Note that mine coordinates are based on anorthwest trending grid. The ore lenses are identified by symbols that are defined in Table 7.1.PLANPROJECTIONMassivesuiphidelensDrillholeintersectionMainZoneExtensionTrumpeterZone.PRICEMINEThelwoodCreekVERTICALSECTIONPROJECTION(3500N)05001000Mt.MyraSOUTHEASTMyraValleyH—WShaftTheiwoodValley-JFigure 7.2. Diagrammatic cross-section of the Buttle Lake camp showing location of ore lenses inthe Myra formation projected onto a stratigraphic section at about 2 000 m east (Figure 7.1).Units are not all continuous out of the section. The Price formation andesite is overlain by Myraformation, which is capped by an apparent unconformity and the Theiwood formation. The felsicH-W horizon, immediately above the Price formation, hosts major deposits such as the H-W andBattle. The Ore Clast Breccia is near the middle of the Myra formation. The Lynx-Myra-Pricehorizon, near the top of the Myra formation, hosts apparently smaller ore lenses. Ore lenses areidentified by symbols defined in Table 7.1. The lenses are located in projected plan and crosssection in Figure 7.1. STK = major discharge stockwork predominantly in andesite. Figure iscompiled from Juras (1987) and Pearson (1993).SOUTHWESTLEGENDHangingwaflandesiteH—WHORIZOI’I()QuartzfeldsparporphyryEJRhyoLitevolcaniclasticsMassivesuiphidePyritestringersPriceandesite/Unconformity9100200300rnApproximateScaleThelwoodformationNorthfault0 8UppermaficUpperrhyoliteUppermixedvotcamclasticsG—flowLynx—Myra—PricehorizonUpperdacite/5EandesiteLowermixedvolcaniclasticsOre—clastbrecciaS•AAAAAAAAAAAAAAAAAtAAAA.’sAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA,AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA,AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAPriceformationVVVH-Wmainlens(Battlezone1000mnorthwest)NORTHEASTrocks. Differences among clusters represent different proportions of the end-membercomponents. Finally, a schematic portrayal of metallogeny of the H-W horizon using the galenalead isotope framework established in the Battle and Gap zones is presented.7.2 ANALYTICAL TECHNIQUES Ai%l1) ERRORSA small (<0.1 gram) cleavage cube of galena was hand picked from each sample andanalyzed by Ann Pickering at the Geochronometry Laboratory, Department of GeologicalSciences, The University of British Columbia. The analyses were done by the silica gel -phosphoric acid method using a single filament on a Vacuum Generators Ltd Isomass 54R solidsource mass spectrometer; results were normalized to the NBS 1 standard (for details see Godwinet al., 1988). Sources of error in mass spectroscopic measurement of lead isotopes include:overall analytical error, run instability, 204Pb-error and fractionation error. Overall analyticalerrors at 2o are on the order of 0.1% based on repeated analysis of the NBS1 standard. Precisionof each run, based on consistency of each block of analyses during each run, is about an order ofmagnitude less than the overall analytical error. The 204Pb-error and fractionation error dependto a large extent on consistency of loading technique and run temperature, and can sometimes bedetected from trends in the analyses. Thus, slopes of204Pb-error and fractionation error areshown on the data plots (Figures 7.4 to 7.6). The 204Pb-error, of course, is not present on the208Pb/6 versus207Pb/6 plots; consequently, this type of plot is more robust and isemphasized in the analysis below.7.3 CHARACTERISTICS OF THE GALENA LEAD ISOTOPES7.3.1 Characterization as Orogene LeadLead evolution, based on simplistic computer simulation of orogenesis, was approximatedfor four major world-scale reservoirs by Doe and Zartman (1981; cf Zartman and Doe, 1981):(i) mantle, (ii) lower crust, (iii) upper crust, and (iv) orogene. Orogene lead,.zo:Figure 7.3. Large scale galena lead isotope plots for the Buttle Lake mining camp, southwesternBritish Columbia. Data are in Table 7.1. (a) 207PbJ4 versus206Pb/4 plot. (b)208Pb/41, versus 206Pb/4 plot. (c) 208Pb/6 versus207Pb/6 plot. Upper crustand mantle curves are from Zartman and Doe (1981). Data from the Buttle Lake deposits clusterbetween the two curves. This is typical of island arc or orogene lead. The age cannot beestimated from the model curves. Mixing lines are shown for the base of the Devonian (d) andfor the base of present day (n). The model curves have the base of each age plotted as: n = now, r= Tertiary, k = Cretaceous, j = Jurassic, t = Triassic, p = Permian, b = Carboniferous, and d =Devonian.90888684207Pb/206Pb*10039,539.0,D38.538.037,5II20.0o20.5* Cd S.,21.021.5wxry 0 C15.6815.6115.5415.4715,40 17.418.118.819.58280Z93formed by mixing of lead from the four reservoirs, is characteristic of lead in island arcs that hasbeen mixed from different provenances by subduction processes. Estimates of lead isotope valuesfor the upper crust and mantle lead evolution curves used in Figures 7.3a to c, are tabulated inGodwin eta!. (1988).Data from Table 7.1 plot between the upper crustal and mantle curves on aversus 206Pb/4 plot, a208Pb/4 versus206Pb/4 plot, and a208Pb/6 versus207Pb/6 plot (Figures 7.3a to c). The lead apparently is orogenic in character because in allthree plots it can be described as a mixture of upper crustal and mantle leads. Andrew (1987),and Andrew and Godwin (1989) showed that lead isotope ratios ofgalena and initial ratios ofwhole rock samples of the Sicker Group plot in the lead isotope ratio field of present day islandarcs adjusted to the Late Devonian.The world-scale model does not define the age of the deposit, which is known to be LateDevonian (370 ± 6 Ma; Juras, 1987). The lead appears to be much younger than its true age andplots near mixing lines between the upper crust and mantle curves for the Triassic (Figure 7.3c)and Cretaceous (Figure 7.3a). Such mixing lines only approximate the age along the morecomplex orogene curve; but the orogene curve of Zartman and Doe (1981) would predict an evenyounger age.7.3.2 Linear Array of Galena Lead Isotope DataGalena lead isotope data in Figures 7.4a to c can be approximated by linear arrays.Potential causes of this linear distribution is examined by three models outlined in Table 7.2,namely: (i) growth in lead isotope ratios over time in an orogene, (ii) mixing between sources withdistinct lead isotope signatures due to oiginal differences in isotopic contribution from mantle andupper crustal sources, and (iii) mixing ofvariably leached radiogenic components from host rocks.Distribution of data due to evolution of the lead within the orogene or island arc over timewould form lines of slope 0.04, 1.15 and 0.12 on Figures 7.4a to c, respectively (Table 7.2:approximate slope of orogene growth curve). Lines of this slope are marked ‘or’ on the plots.Differences due to orogene mixing (i.e. generally between mantle and upper crust) shouldform linear arrays that have slopes close to 0.18, 1.01 and 1.61 on Figures 7.4a to c, respectively(Table 7.2: mantle - upper crust mixing model). Lines of this slope are marked mx’ on the plots.Differences due to selective leaching are not easily assessed without partial leachingexperiments. However, it is well known that partial leaching of a rock can selectively extract arelatively radiogenic component (cf Doe and Delevaux, 1972). The theory behind chemicalseparation of isotopes in this instance is that the uranium and uranogenic lead is readily leachedbecause of incompatibility in most crystal structures and associated metamict damage. The majorlead bearing minerals in common rocks, feldspars and sulphides, remain in the source. Thus,selective leaching can produce the markedly radiogenic arrays noted in some carbonate hosteddeposits and in some silver rich vein systems (Godwin eta?., 1982; Robinson and Godwin, inpress; Crocetti eta?., 1988; Heyl, 1969; Heyl eta?., 1974). Slopes on markedly radiogenic linesare due to mixing of leached radiogenic components with a relatively non-leached, non-radiogenicprimary component. The slope is probably process dependent and does not relate directly to age.The slopes of two markedly radiogenic lines (cf Godwin eta?., 1982) are used as a firstapproximation for evaluation of the effect of selective leaching in host rocks. In Table 7.2 theslopes of the markedly radiogenic lines related to carbonate hosted deposits are: 0.10, 1.44 and0.09, as related to Figures 7.4a to c, respectively. For silver rich veins associated with Cretaceousintrusions the equivalent set of slopes is: 0.10, 0.97 and 0.15 on Figures 7.4a to c, respectively.These latter slopes are marked ‘lv’ on relevant plots.The best discriminator of these differences in slope is Figure 7.4c (cf Figure 7.5), the208Pb/6 versus207Pb/6 plot. The slope cannot be defined in Figure 7.4b because ofTABLE7.2.CALCULATEDSLOPESFORLEADISOTOPEPLOTSTOTESTMODELCONCEPTS.LINESCORRESPONDINGTOSLOPESBELOWAREPLOTTEDONFIGURES7.4AANDC,AND7.5.Model207Pb/4bversus208Pb/4bversus2O8Pb/ôPb*10versus206Pb/4b206PbI4b207Pb/6b*100Orogenegrowth’(or)0.041.150.12Mantle-uppercrustmixing2(mx)0.181.010.16Leaching: markedlyradiogeniclinesfor Devonian0.101.440.09sedimentaiyexhalitiveandcarbonatehosteddeposits3 Leaching: markedlyradiogeniclinesforsilver0.100.970.15richveinsassociatedwithCretaceousplutons4(Iv)1 Averageslopeoforogenegrowthcurve(afterZartmanandDoe,1981,andtabulatedinGodwineta!.,1988) fromthebaseoftheDevonian(0.41Ga)tothebaseoftheTriassic(0.25Ga).Lines ofthisslopeonFigures7.4aandc,and7.5aremarked‘or’.2Meanofniixing4ineslopesfortheDevonian(0.41Ga), Carboniferous(0.36Ga)andthePermian(0.29Ga).SlopesarecalculatedformixinglinesbetweenthegrowthcurvesdefinedbyZartmanandDoe(1981)andtabulatedinGodwineta!.,(1988).Lines ofthisslopeonFigures 7.4aandc,and7.5aremarked‘mx’.3 Estimatedslope(cjGodwineta!.,1982) forleachingage basedonmarkedlyradiogenicmixinglinesbetweenJason(Godwin eta!.,1988:10077-AVG(n=5),p.154)andRobbLake(30410-AVG(n=5),p.160).4Estimatedslope(cfGodwinetal.,1982) forleachingagebasedonmarkedlyradiogenicmixinglinesbetweenKenoHill(Godwin eta!.,1988:10086-AVG(n=4),p.154)andPeso-Rex(10085-002(xi=1),p.155).LinesofthisslopeonFigures 7.4a andc,and7.5aremarked‘Iv’.0•the similar slope in all models tested (Table 7.2: m = 1.2 for orogene growth, m = 1.0 for mantle- upper crustal mixing, and m = 0.97 to 1.44 for leaching). The data in Figure 7.4c (linearregression line ‘dt’) is distinct from the age trend for orogene growth (or). However, the trend ofthe data (dt) parallels closely the mixing line trend (mx), and is indistinguishable from the range ofestimated leaching trends, especially for silver rich vein deposits associated with Cretaceousplutons (Iv).7.3.3 Definition of Clusters and End MembersDifferences in galena lead isotope ratios exist among ore lenses in the Buttle Lake miningcamp. The small scale 207Pb/4 versus206Pb/4 plot, 208Pb/4 versus206Pb/4 plot and 208Pb/6 versus207Pb/6 plots (Figures 7.4a to c, respectively)show these variations. Three clusters were determined by multivariate cluster analysis (Kmean,SYSTAT: Wilkinson et al., 1992) of all the isotope ratios for all samples in Table 7.1. Theseclusters are defined in Tables 7.1, 7.3 and 7.4. They can be seen in Figures 7.4 to form slightlygapped clusters along an overall linear trend. Figure 7.5, a plot of averages for each lens (Table7.3), shows the clusters more clearly. Cluster 1, albeit represented by one sample, is from the OreClast Breccia (X). Cluster 2 contains analyses from the Gap (G), Battle Upper and Main zonelenses (U and B), H-W North Lenses (Bomite zone, N), H-W Upper Zinc (A), Lynx H zone (H)and the Myra lens (Y). Cluster 3 contains data from the Battle Main lens (B), H-W Main lens(M), H-W Upper Zinc (D and C), H-W North lens (K-stope, K), Lynx S and West G zones (Sand W), Ridge zone (R) and Price lens (P).7.3.4 Relationships among Clusters, Ore Lenses, and Host and Footwall RocksTable 7.4 summarizes stratigraphic position (H-W versus Lynx-Myra-Price; section 3.1) andhost rock affiliations with each of the ore lenses. The stratigraphy of the Lynx-Myra-Pricehorizon down to the Ore Clast Breccia is not known in as much detail as the H-W horizon.Consequently, some of the best controls to the affiliations noted below are from the Battle andTABLE7.3.AVERAGEGALENALEADISOTOPERATIOS1FORLENSESWITHiNTHEBUTTLELAKEMININGCAMP,SOUTHWESTERNBRITISHCOLUMBIALABNORUNSLENSHORIZON2SYMBOLRANKORDER206PW204Pb207Pb’204Pb20Pb’204Pb207Pb’206Pb208Pb’206Pb1flfl‘1OClusterIOREN=1OreClast Breccia3Ore-X1118.44815.56438.08784.37120.647Cluster2GAPN=5GapH-WG218.48615.57538.12884.25020.626BATTLEN3Battle:UpperH-WU318.50115.57638.14884.19220.616LYNXN=1Lynx:IOre-X(?)I418.50115.57438.14284.18320.616H-WN5H-W: North(Bornite)H-WN518.49215.56938.11184.19020.611LYNXN=1Lynx:HOre-X(?)H618.51615.57938.16484.13420.611H-WN=1H-W:UpperZincH-WA718.51115.57638.14684.14520.608MYRAN=6MyraL-M-P(?)Y818.49615.56338.10584.14720.602Ore-X(?)BAITLEN=4Battle:MainH-WB918.50815.57038.13184.12920.603Cluster3H-WN1H-W:UpperZincH-WD1018.53315.57238.14784.02720.584H-WN1H-W: UpperZincH-WC1118.53715.57538.15784.02020.584RIDGEN=1RidgeWestH-W(?)R1218.55415.58238.19583.98320.586PRICEN=1PriceL-M-PP1318.53415.56838.14084.00020.580BATTLEN’5Battle:MainH-WB1418.55 115.57838.18083.97320.58 1LYNXN’2Lynx: WestG(V)L-M-PV1518.54915.57438.16083.96520.574FI-WN=3H-W:MainH-WM1618.55715.57838.17983.94420.573LYNXN=2Lynx: WestG(W)L-M-PW1718.55715.57438.17183.92620.569LYNXN=3Lynx:SL-M-PS1818.55615.57138.16283.91120.565H-WN=1H-W:North(Kstope)H-WK1918.56615.57438.17883.88820.565Mean±2std.deviationsN=19ORELENSES318.524±.06415.573±.01038.149±.05484.073±.26820.595±.046IAllanalysesweredonebyA.Pickering,GeochronometryLaboratory,Department ofGeological Sciences,TheUniversityof BritishColumbia.2MineNomenclatureUseshorizon’:H-W=H-WHorizon;L-M-P=Lynx-Myra-PriceHorizon;Ore-X=OreClast Breccia.3EstimatesofLateDevonianorogeneleadisotopevalueforWrangellia,andmorespecifically, theMyraformationoftheSickerGroup(seetext).f\) 0TABLE7.3.AVERAGEGALENALEADISOTOPERATIOS’FORLENSESWITHINTHEBUTTLELAKEMININGCAMP,SOUTHWESTERNBRITISHCOLUMBIALABNORUNSLENSHORIZON2SYMBOLRANKORDER206PW4pb207Pb”4b208Pb”4b207PW6b208Pbi°’PbviflOCluster1OREN=1OreClastBreccia3Ore-X1118.44815.56438.08784.37120.647Cluster2GAPN=5GapH-WG218.48615.57538.12884.25020.626BATTLEN=3Battle:UpperH-WU318.50115.57638.14884.19220.616LYNXN1Lynx:IOre-X(?)I418.50115.57438.14284.18320.616H-WN=5H-W:BorniteH-WN518.49215.56938.11184.19020.611LYNXN=1Lynx:HOre-X(?)H618.51615.57938.16484.13420.611H-WN=1H-W:UpperZincH-WA718.51115.57638.14684.14520.608MYRAN=6MyraL-M-P(?)Y818.49615.56338.10584.14720.602Ore-X(?)BATTLEN=4Battle:MainH-WB918.50815.57038.13184.12920.603Cluster3H-WN=1H-W:UpperZincH-WD1018.53315.57238.14784.02720.584H-WN=1H-W:UpperZincH-WC1118.53715.57538.15784.02020.584RIDGEN=1RidgeWestH-W(?)R1218.55415.58238.19583.98320.586PRICEN=1PriceL-M-PP1318.53415.56838.14084.00020.580BA1TLEN=5Battle:MainH-WB1418.55 115.57838.18083.97320.581LYNXN=2Lynx:WestG(V)L-M-PV1518.54915.57438.16083.96520.574H-WN=3H-W:MainH-WM1618.55715.57838. 17983.94420.573LYNXN=2Lynx:WestG(W)L-M-PW1718.55715.57438.17183.92620.569LYNXN=3Lynx:SL-M-PS1818.55615.57138. 16283.91120.565H-WN=1H-W:North(K)H-WK1918.56615.57438.17883.88820.565Mean±2std.deviationsN=19ORELENSES318.524±.06415.573±.01038.149±.05484.073±.26820.595±.0461AllanalysesweredonebyA.Pickering,GeochronometryLaboratory,Department ofGeologicalSciences,TheUniversityofBritishColumbia.2MineNomenclatureUses¶horizon’:H-W=H-WHorizon;L-M-P=Lynx-Myra -PriceHorizon;Ore-X=OreClastBreccia.3EstimatesofLateDevonianorogeneleadisotopevalueforWrangellia,andmorespecifically,theMyraformationoftheSickerGroup(seetext).TABLE1.4.HORIZON1ANDHOSTROCKAFFILIATIONSWITHORELENSES,BUTLELAKEMIMNGCAMP,SOUTHWESTERNBRITISHCOLUMBIARANKORDERLENSHORIZON1SYMBOLASSOCIATEDUNITSENDMEMBERCOMMENTS(seeFigure7.5)(Tables7.1,7.3)POSiTION(Figures7.1,2)(Figure7.2)AFFILIATIONCLUSTERI1OreclastbrecciaunknownXOreclastbrecciaRhyolitePossibleendmemberCLUSTER22GapH-WGQuartzfeldsparporphyryRhyolitePossiblenearendmember.Pricefonnation(?)Andesite3Battle:UpperH-WURhyolitevolcaniclasticsRhyolitePossiblenearendmember.4Lynx:IOre-X(7)IOreclastbreccia(7)RhyolitePossiblenearendmember.5H-W:North(Bomite)H-WNRhyolitevolcarnclasticsRhyolite6Lynx:HOre-X(7)HOreclastbreccia(7)Rhyolite7H-W:UpperZincH-WARhyolitevolcaniclasticsRhyolite8MyraL-M-P(7)YLynx-Myra-Pricehorizon(7)RhyoliteOre-X(7)Oreclastbreccia(?)Rhyolite9Battle:MainH-WBPriceformationAndesiteImmediatelyabovedischargestockworkinPriceformation.CLUSTER310H-W:UpperZincH-WDRhyolitevolcaniclasticsRhyolite11H-W:UpperZincH-WCRhyolitevolcaniclasticsRhyolite12RidgeWestH-W(7)RRhyolitevolcaniclasticsRhyolite13PriceL-M-PPLynx-Myra-PricehorizonRhyoliteLowermaficvolcanicsAndesite14Battle:MainH-WBPriceformationAndesiteImmediatelyabovedischargestockworkinPriceformation.15Lynx:WestG(V)L-M-PVLynx-Myra-PricehorizonRhyoliteSEandesiteAndesite16H-W: MainH-WMPriceformationAndesiteImmediatelyabovedischargestockworkinPriceformation.17Lynx:West0(W)L-M-PWLynx-Myra-PricehorizonRhyoliteSEandesiteAndesite18Lynx:SL-M-PSLynx.Myra-PricehorizonRhyoliteImmediatelyabovedischargeSEandesiteAndesitestockworkin5Eandesite.19H-W:North(Kstope)H.WKPriceformationAndesiteImmediatelyabovedischargestockworkinPriceformation.Possibleendmember1Minenomenclatureuses‘horizon’:H-WH-Whorizon;L-M-P=Lynx-Myra.Pricehorizon;Ore-X=OreClastBreccia.0Figure 7.4. Small scale galena lead isotope plots for the Buttle Lake mining camp, southwesternBritish Columbia. Data and symbols are in Table 7.1. (a) 207Pb/4 versus 206Pb/4 plot.(b) 208Pb/4 versus206Pb/4 plot. (c) 208Pb/6 versus207Pb/6 plot. The datadefine three distinct clusters. Cluster 1 (albeit only one point) = Ore Clast Breccia. Cluster 2 =samples from lenses hosted mainly in felsic units (Table 7.4). Cluster 3 = samples from lensesabove stockwork feeder zones mainly within andesite (Table 7.4). The data can be represented bya best-fit line (dt). Three models to explain the slopes of the arrays are (Table 7.2): orogenegrowth (or), mantle - upper crust mixing (mx), and selective leaching of footwall rocks (Iv). Thelinear regression line through the data is marked ‘dt’. All lines are plotted through the arithmeticmean. The line through the data (dt) in a, and especially, c is closer in slope to the mixing vector(mx; cf Figure 7.5) and to the trend for selective leaching (lv) than to the slope of the orogenegrowth curve (or). Errors at two sigma are less than the symbol size. F= trend of fractionationerror. 4= trend of204Pb error.38.3020.57020.5920.61N20.6320.5538.24.38.1838,1238.0620.65 84.484.384.284.184.083.983.8207Pb/b*1004-Figure 7.5. Small scale galena lead plot of208Pb/6 versus207Pb/6 for the Buttle Lakemining camp, southwestern British Columbia. This plot eliminates 204Pb error. Averaged valuesfor each ore lens are plotted to simplif,’ the diagrams and assist in their interpretation. Data andsymbol codes are in Table 7.3 and Figure 7.4. The slope of the data for the lenses (dt)corresponds closely to the mixing-line trend between upper crust and mantle models (mx), and tothe slope predicted for selective leaching (lv). F = trend of fractionation error.20.5520.57020.59(0 0 (‘120.6120,6320.65 84.484.384.284.184.083.983.8207Pb/206Pb*100Z..ILjGap zones. Cluster 1 of one point is a galena lead analysis from a suiphide fragment in the OreClast Breccia (section 3.1; Juras, 1987; Juras and Pearson, 1990). A significant feature of the OreClast Breccia is that it contains olistoliths of pyrite-mineralized rhyolite coarse tuff to lapilli tuffthat are up to 50 m long by 15 m wide (Juras, 1987). Many of the olistoliths contain semi-massive to massive suiphide + barite + quartz pods. It also locally contains dacite fragments.Fragments coarsen to the southeast near the Price deposit. Dacite clasts and size distributionindicates a southeastern provenance, perhaps many kilometers away. However, mineralization,and therefore, the source of lead, appears to be closely associated with rhyolite. Lead isotoperatios from the Ore Clast Breccia anchors the end of the linear array in Figure 7.5, and therefore,appears to represent one end member.The other end member may be represented by the H-W North lens (K stope) in cluster 3(Figure 7.5; symbol K). This lens is underlain by Price formation andesite that is extensivelyaltered to a quartz-sericite-pyrite discharge stockwork (Figure 7.5; section 6.2.1). The Battlezone (B) and H-W main lens (M) occur above stockwork altered Price formation andesite. Lynx-Myra-Price horizon lenses that plot in cluster 3 are also underlain by altered andesite. Theseinclude Lynx (S) and the Price lens (P). Thus, the end members are related spatially to majordischarge stockworks in andesite.By comparison, most deposits in cluster 2 are associated with a footwall composed ofeither: (i) rhyolite, (ii) andesite, or (iii) rhyolite and andesite. Within H-W horizon, the BattleUpper (U) zone is the only lens that is associated exclusively with rhyolite. It is underlain byrhyolitic tuffaceous sediments and overlain by quartz feldspar porphyritic rhyolite (section3.2.2.6). The Gap Lens (G) is likely underlain by Price andesite that is intruded by quartzporphyritic rhyolite. Lenses in the Lynx-Myra-Price horizon that plot in cluster 2 are Lynx H (H)and Lynx I (I). They are associated with felsic volcaniclastics, as is the Myra lens (Y).There is an apparent relationship between the isotopic composition of the lead in themassive sulphide lenses and geological setting. Points that appear to be significant include:1. Mineralization that is most closely associated with rhyolite contains isotopically “primitive0end member lead (cluster 1: Ore Clast Breccia; cluster 2: Battle upper zone).2. The most radiogenic lead is associated with massive sulphide lenses formed immediatelyabove discharge stockworks in andesite (cluster 3: H-W North (K stope), and Lynx S).3. End members (1 and 2, above) and samples that plot between them define a mixing line.4. Mineralization associated with the primitive end members (Ore Clast Breccia, Gap andBattle upper zone), is characterized by a zinc and lead rich, but relatively copper poor,metal association.5. Mineralization associated with the radiogenic end members (H-W K-stope and Lynx Szone) are relatively copper rich and lead poor.6. The Battle main lens is characterized by both primitive lead (rank 9: Table 7.4) and moreradiogenic lead (rank 14: Table 7.4).7. Lynx lenses (V, W and S) are hosted within the felsic Lynx - Price horizon, but have aradiogenic end-member fingerprint.8. The signature of the Myra deposit is within cluster 2. Its stratigraphic position has beenplaced traditionally within the Lynx-Myra-Price trend (Walker, 1985; Juras 1987; Juras andPearson, 1990). However, this location currently is unresolved; it might be associated withthe stratigraphically lower Ore Clast Breccia unit (Figure 7.2; S. Juras, writtencommunication, 1994). In both instances the mineralization apparently would be associatedclosely spatially to rhyolitic rocks.9. The largest known orebodies in the Buttle Lake camp, including the H-W main lens andBattle lens, are associated with the relatively radiogenic cluster 3.7.4 DISCUSSIONLarge isotopic variations, such as those reported in the Buttle Lake camp, are rare inaccounts of volcanogenic massive sulphide (VMS) and sedimentary exhalative (SEDEX) deposits.However, galena lead isotopes in Kuroko deposits in the Hokuroko District of Japan havevariable ratios among deposits, and variations between yellow and black ores within deposits.Fehn et al. (1983) suggest that these shifts in the lead isotope ratios are due to varied footwallsources of the lead during the evolution of the hydrothermal systems related to ore deposition.Lady Loretta, a SEDEX shale hosted deposit near Mt. Isa in northwestern Queensland, Australia,contains significant internal lead isotopic variation (Gulson, 1985, 1986). Variations areassociated with ores of distinct textural type; an explanation for the differences was not presentedby Gulson. Extreme variations of markedly radiogenic lead are well known in carbonate hosteddeposits and silver rich pluton-associated veins (e.g. Godwin et a!., 1982). The markedlyradiogenic character of the lead isotopes apparently arises from selective leaching of lead fromzircon and other minerals that contain uranium along the pathways of mineralizing fluids.Analysis of galena lead isotope data from the Buttle Lake mining camp indicates that, onaverage, it has an orogene or island arc character. The trend in the galena lead data can bedescribed as a mixing line. This trend does not relate to age differences among the ore lenses, butit appears to mimic either: (i) varied mixing of upper crustal and mantle components, as might beexpected in an orogene or island arc environment, or (ii) variable selective leaching of lead isotopecomponents from footwall source rocks. A combination of these processes is not excluded. Thenon-radiogenic end members appears to be spatially related to rhyolitic host rocks. The mostradiogenic deposits, also apparently the largest, occur immediately above major dischargestockworks in andesite. These points are elaborated upon below.7.4.1 Orogene or Island Arc CharacteristicsThe orogene or island arc character of the lead is supported by its position between theidealized mantle and upper crustal curves, and its position within present day island arc fields backcalculated to Late Devonian. The mean in Table 7.3 for the galena lead isotope ratios of the orelenses sampled likely is a good approximation of orogene or arc-generated Late Devonian (Ca.370 Ma) lead isotope ratios in Wrangellia, and more specifically, for the Myra formation of theSicker Group. The values and variation at two standard deviations for this are (Table 7.3):206Pb/4 = 18.524 ± 0.064; 207Pb/4 = 15.573 ± 0.010; 208Pb/4 = 38. 149 ± 0.054;207Pb/6 (x 100) = 84.073 ± 0.268; and 208Pb/6 (x 10) = 20.595 ± 0.046. However, ifthe radiogenic end of the data array is caused only by selective leaching, the value for the OreClast Breccia should be closer to the overall orogene value. These less radiogenic values are:206Pb/4 = 18.448; 207Pb/4 = 15.564; 208Pb/4 = 38.087; 207Pb/6 (x 100) =84.37 1; and 208Pb/6 (x 10) = 20.647.7.4.2 Lack of Age Constraint by Galena Lead Isotope DataThe age is not defined in Figures 7.4c and 7.5 because the best-fit-line through the data (dt)is distinctly steeper than the age trend marked by the slope of the orogene curve (or). Anotherreason that the variation in lead isotopes among the lenses do not represent time differences is thatdata within the upper part of the trend (cluster 3) are represented by lenses from both thestratigraphically lowest (Table 7.1 and Figure 7.2: H-W horizon) and the highest (Table 7.1 andFigure 7.2: Lynx-Myra-Price horizon) ore-bearing units. For example, cluster 3 includes datafrom the Battle main lens in the H-W horizon, and the Lynx S and West G zones in the Lynx-Myra-Price horizon.7.4.3 Implications ofUpper Crust - Mantle Mixing ModelThe mixing line trend of the data (dt) is compatible with the trend expected from variedmixing between upper crustal and mantle reservoirs (mx). The end members would thereforelikely be represented by isotopically distinct magmas and resultant rock types. Such variations inlead isotopes in volcanic rocks have been correlated with different magma type by Dupre andEcheverria (1984). In the Buttle Lake camp the most obvious candidates, by reference to Table7.4, are: (i) a rhyolite source for the relatively primitive lead, and (ii) an andesite source for therelatively radiogenic lead.Several of the lenses associated with primitive lead (e.g. Gap, Battle upper and Myra) arerich in lead and zinc, and are accompanied by abundant barite. The radiogenic lenses (e.g. BattleMain, H-W K stope), on the other hand, are markedly rich in copper and contain sparse galena.Such differences can be due to several causes, such as temperature differences and progressivezone replacement. But the lead association with rhyolite may strengthen the argument that therhyolite is an end member source of mineralization. For example, the lead-zinc-barite richcharacter, as well as the lead isotope signature, of the Myra deposit support a rhyolite affiliation.7.4.4 Implications of Selective Leaching ModelThe mixing line trend of the data (dt) is compatible with the trend expected from mixingofvaried selective leaches of footwall rocks (Iv). The most likely source candidate for therelatively primitive end member is rhyolite (the same argument that was used above applies heretoo). The radiogenic end member would be leached selectively from any of the footwall rocks.Such a process would be particularly affective in areas of stockwork. This is compatible with theobservation that the most radiogenic lead in cluster 3 is from deposits immediately aboveextensive discharge stockworks. The fact that it is in andesite may be irrelevant, because in thismodel the andesite may originally have had the same lead isotope fingerprint as the rhyolite.7.4.5 A Genetic Model for Mineralization in the Battle and Gap ZonesIt is argued here that the large variations in the Buttle Lake camp are from mixing of leadof two types. The mixing line trend associated with the ore lens data (dt) is compatible with twomodels. The first, orogene mixing between mantle and upper crust (mx), implies geneticallyunrelated rock types--probably primitive rhyolite and radiogenic andesite. The second, whichinvolves mineralization from fluids that selectively leached footwall rocks (Iv), also defines a21c17.4, are: (1) a rhyolite source for the relatively primitive lead, and (ii) an andesite source for therelatively radiogenic lead.Several of the lenses associated with primitive lead (e.g. Gap, Battle upper and Myra) arerich in lead and zinc, and are accompanied by abundant barite. The radiogenic lenses (e.g. BattleMain, H-W North (K stope)), on the other hand, are markedly rich in copper and contain sparsegalena. Such differences can be due to several causes, such as temperature differences andprogressive zone replacement. But the lead association with rhyolite may strengthen theargument that the rhyolite is an end member source of mineralization. For example, the lead-zincbarite rich character, as well as the lead isotope signature, of the Myra deposit support a rhyoliteaffiliation.7.4.4 Implications of Selective Leaching ModelThe mixing line trend of the data (dt) is compatible with the trend expected from mixingof varied selective leaches of footwall rocks (Iv). The most likely source candidate for therelatively primitive end member is rhyolite (the same argument that was used above applies heretoo). The radiogenic end member would be leached selectively from any of the footwall rocks.Such a process would be particularly affective in areas of stockwork. This is compatible with theobservation that the most radiogenic lead in cluster 3 is from deposits immediately aboveextensive discharge stockworks. The fact that it is in andesite may be irrelevant, because in thismodel the andesite may originally have had the same lead isotope fingerprint as the rhyolite.7.4.5 A Genetic Model for Mineralization in the Battle and Gap ZonesIt is argued here that the large variations in the Buttle Lake camp are from mixing of leadof two types. The mixing line trend associated with the ore lens data (dt) is compatible with twomodels. The first, orogene mixing between mantle and upper crust (mx), implies geneticallyunrelated rock types--probably primitive rhyolite and radiogenic andesite. The second, whichZZolinear trend with two end members. Association with rhyolite is dominant at the least radiogenicend, and discharge stockworks in andesite are apparently significantly associated with the otherend. The primitive end member rhyolite is common to both models. The variable leaching modelcan readily explain some significant features such as: (i) the juxtaposition of both primitive andradiogenic lead within the Battle Main lens, (ii) the radiogenic lead of the Lynx G and S lenses (V,W and S) within felsic rocks of the Lynx-Myra-Price horizon. For the first, convection cells canbe envisioned to be irregular such that fluids with different scavenging histories discharge at thesame point. For the second, the Lynx S lens might be related to selectively scavenging convectioncells discharging through the underlying stockwork marked in Figure 7.2. The slightly alteredfootwall of the Lynx G lenses might produce the most radiogenic lead because it represents aninitial leach of footwall rocks--initial leaches are commonly markedly radiogenic. Overall, theapplicability of the selective leach model appears to be better than the orogene mixing model. Buta definitive origin cannot be resolved.Variations in mixing of galena lead isotopes are well represented in the Battle and Gapzones in the H-W horizon. Because this is the focus of this thesis, the following discussionemphasizes the derivation of lead for the isotopically distinct massive sulphide lenses within thesezones.There are two general sources metals for volcanogenic deposits: magmatic fluids and/orthe metals leached from footwall rocks. Crystallizing magmas can evolve a hydrous phase that isrich in metals (Whitney, 1989). However, sulfhr, oxygen and hydrogen isotope ratios, traceelement abundances and fluid inclusion data from sea-floor deposits indicate the metal-bearingfluids are dominantly seawater (Thode and Monster, 1965; Sangster, 1968; Craig, 1969). Corliss(1971) proposed that hot, convecting seawater leached metals from volcanic glass in the subseafloor volcanic pile. These fluids when exhaled on the seafloor form stratiform deposits. A hybridprocess involving leaching and magmatic processes has been proposed by Sawkins and Kowalik(1981); they suppose the operation of relatively long-lived seawater convection systems on which221are superimposed pulses of metal rich magmatic fluids. This hybrid process is compatible with theinterpretation of the galena lead isotope mixing model, above.Following the hybrid process (Sawkins and Kowalik, 1981) and the lead mixing model,metals for massive suiphide lenses in H-W horizon were probably variably leached from the Priceformation andesite. Locally, the selectively leached fluids may have been combined with metalsfrom a magmatic fluid associated with the rhyolites. The following sequence of events isenvisioned (Figure 7.6):1. A rift-basin, developed within an andesitic arc is represented, at least in part, by the Priceformation andesite. Mineralization was penecontemporaneous with subsidence and activeblock faulting. In such extensional regimes, seismic pumping processes may channel fluidstoward the surface (Sibson eta!., 1975; cf Russell, 1978, 1983; cf Cathles, 1993). Thisis compatible with the observed relationship of many stratiform deposits to fault zones andlocalization close to steeply dipping fracture systems (LeHuray et a!., 1987; Large, 1992;Kerr and Gibson, 1992).2. Hydrothermal convection cells developed within the andesitic footwall (cf Cathies, 1993),that leached lead and other metals for subsequent deposition to ore lenses above dischargestockworks. Thus, formation of cluster 3 deposits is compatible with the selectiveleaching of host rocks of the same lead isotope composition, or with leaching of andesiteof different lead isotope composition.3. A felsic volcanic regime developed contemporaneously near the rifled basin.Devolatilization of a nearby felsic magma chamber may have contributed metal-richmagmatic water to the ore-forming hydrothermal system. A relatively “primitive” leadcontribution in the magmatic water would shift the lead isotope values towards cluster 1isotopic values. The Gap massive suiphide lens plots near the cluster 1 end memberZzz(Figure 7.5). Because there are no apparent rhyolite units in the footwall below the Gapto leach at the time of ore deposition, a magmatic fluid component is supported.4. H-W horizon volcaniclastics, fine rhyolitic tuffaceous deposits through to rhyolitictuffaceous sediments (Figure 3.1), were deposited.5. Battle upper zone massive suiphide lenses were deposited above the rhyolitevolcaniclastics. The Battle upper zone is underlain by a polymetallic stockwork in thevolcaniclastic unit, but occurs above the Battle main zone. It is reasonable to envision thathydrothermal fluids continued to circulate upwards through the Battle main lens andleached some metals from the overlying volcaniclastic package prior to exhaling onto theseafloor. The resulting upper zone mineralization would have a mixed lead isotopesignature (cluster 2).223Figure 7.6. Evolution of mineralization in the Battle and Gap zones, Buttle Lake mining camp,southwestern British Columbia. The main Battle zone is deposited directly over an intensestockwork in the underlying Price andesite. Its stratigraphic position is equivalent to the H-Wmain zone. Lead in these deposits is relatively radiogenic, and arguably, is from selective leachingof andesite. Gap mineralization is also above a stockwork in Price andesite but contains a lessradiogenic lead component. The difference in isotopic character emphasizes a different origin forthe two types of lead. Lead for the Gap zone may be at least partly from a rhyolite magmaticfluid. The Battle upper zone is within the felsic H-W horizon and is characterized by anunderlying polymetallic stringer zone. Its lead isotope characteristics are intermediate incomposition implying variability to the selective leach process and/or mixing of lead leached fromandesite and rhyolite; a magmatic component cannot be discounted.LegendoorserhyoliticpyroclosticdepositsFinerhyohtictuffoceous2!itsMainBottlemassivesulphidelensvvvvvvvvvvvvvvvvvvvvvvvvvvvv.vvvvLectctevolutioninH—WHorizonRhyoliteflow—domecomplexUpperzonemassivesulphidesRhyolitictuffaceoussediments++•++++++--Rhyolitetuftwithpumiceblocks.PumiceouslapillituftSeaLevelUpperzone,cluster2,rodiogenicPriceandesiteapzone,H—Wnorthbornitelensescluster2“primitive” +fluidcompBottlezone,H—Wmainzone7++cluster31++++1+++++I+++++11+++++If+++++11+++++ConvectingfluidwithleachedmetalsApexoffelsicmagmachamber2Z5CHAPTER 8.CONCLUSIONS8.1 INTRODUCTIONThe three main goals in this project were to: (i) unravel the stratigraphy of the Battle zoneusing detailed logging and petrographic and lithogeochemical techniques, (ii) define the alterationof units associated with the main Battle zone massive sulphide lens, and (iii) describe and explainthe origin of multiple suiphide horizons within the Battle zone. Chapter 3 describes thestratigraphy of the Battle zone in detail, and presents a preliminary stratigraphy for the Gap zone.Lithogeochemistry in Chapter 4 further characterizes the rock units defined in Chapter 3 and someof the relationships among them. Characterization of both hangingwall and footwall alteration tothe Battle zone follow in Chapter 5. Massive sulphide lenses are described in Chapter 6. Theorigin of the different mineralized horizons in the camp, addressed in an investigation of galenalead isotopes, is in Chapter 7.Highlights of major sections of the thesis are addressed below.8.2 STRATIGRAPHY8.2.1 Lithology and Stratigraphic SequenceH-W horizon in the Battle zone was found to consist of the following lithologic units: (i)Battle and Gap zone massive suiphide lenses, (ii) fine rhyolitic tuffaceous deposits, (iii) H-Wmafic sills, (iv) coarse rhyolite pyroclastic deposits, (v) rhyolite tuffaceous sediments, (vi) upperzone massive sulphides, and (vii) rhyolite flow-dome complex. Detailed geologic correlations onthree sections (Section 13+72E, Section 15+85E and Section 17+98E) supports the followinggeologic interpretations:1. The Battle and Gap zone massive sulphide lenses probably occur at the samestratigraphic position (i.e. overlying the Price andesite).2. The H-W mafic unit is a shallow level sill characterized by brecciated and peperiticmargins.3. Battle zone cherts are silicified rhyolite ash.4. Coarse rhyolitic tuffaceous deposits and rhyolitic tuffaceOus sediments could representa welded pyroclastic flow and co-ignimbrite ash cloud respectively.5. The quartz porphyritic (QP) member of the rhyolite flow dome complex is probably ashallow level sill that intrudes the Price andesite and tuffaceous units ofH-W horizon.6. The quartz feldspar porphyritic rhyolite (QFP) and green quartz feldspar porphyriticrhyolite (GQFP) have a physical morphology consistent with them being volcanic flowsrather than intrusions.Points one and three, above, are controversial and are discussed below.The first conclusion states that the Gap massive suiphide lens was probably deposited at thePrice formation contact. If this is true, the Gap lens is correlative with the Battle zone and thegiant H-W lens. Hydrothermal systems closely related in space and time in the Buttle Lake campbasin, therefore, would have been responsible for formation of all the lenses. The time ofdeposition of the main Battle and the H-W massive suiphide lenses is well constrained. Clearly,they were mostly formed during a period of quiescence prior to the onset of felsic volcanism. Thetiming ofthe Gap lens is more ambiguous. Massive quartz porphyritic (QP) rhyolite occurs in thefootwall to the Gap zone. The contacts are obscured and yield little information about the modeof deposition. It is generally, but not everywhere, overlain by a thin interval of altered andesite,followed by massive sulphides. Two alternative explanations for the stratigraphy in the Gap zoneare: (i) the rhyolite was extruded as a flow, overlain by an andesite lava or debris flow, thenoverlain by massive suiphides, or (ii) rhyolite intruded the basement following deposition of theZ27overlain by massive sulphides, or (ii) rhyolite intruded the basement following deposition of themassive suiphide lens. The first explanation has several problems. First, the relative timing ofmassive suiphide deposition and rhyolite volcanism is opposite to that observed elsewhere on theproperty where deposition of massive suiphides precedes rhyolite volcanism. Second, the degreeof alteration sustained by the rhyolite in the Gap sequence is much less than that in the andesite.If rhyolite were deposited prior to massive suiphides, the development of pyrite stringers ought tobe uniformly intense throughout the immediate footwall to the Gap lens. The hypothesis that therhyolite is a later intrusive event is more satisfactory because: (i) it accounts for the difference inintensity of alteration in the rhyolite versus the andesite, (iii) the major ore lenses appear to berelated to the same broad hydrothermal system, and (iv) extrusion of rhyolite flows proceeded in asimple, progressive manner following deposition of the rhyolite pyroclastic units.This interpretation, however, is not definitive because only two holes were logged throughthe Gap zone (DDH 14-757; Figure 3.2 and DDH 14-720), both of which were close to faultzones. Figure 3.2 shows that the footwall of the Gap zone is dominantly what appears to bealtered Price andesite, with lesser intrusive quartz porphyritic (QP) rhyolite (section 3.2.2.7). It ispossible, however, that the altered “Price andesite” below the Gap zone is actually an inter-H-Whorizon andesite. This inter-andesite could be a late phase of the Price formation or an earlyphase of the hangingwall andesite (S. Juras, written communication, 1994).The conclusion that Battle zone chert is silicified rhyolite ash is supported by thelithogeochemistry (section 5.2.1). What remains in question is whether or nor the cherts are trueexhalites, or at least contain an exhalite component. Are they distal and proximal,contemporaneous and late stage products of the same hydrothermal systems responsible forforming the massive sulphide deposits--following the definition of Kalogeropoulos and Scott,(1983)? Are they formed solely by silica replacement of preexisting felsic volcanic ash? Thesequestions were not resolved in this thesis, however, the following review of several exhaliteoccurrences emphasizes that Battle zone cherts are certainly not typical “exhalites”.Tuffaceous exhalites (tetsuseiki) in the Fukazawa mine, Hokuroku District, Japan, occurprimarily as beds, but also as breccia networks cementing hanging wall breccia fragments. Thechemical component consists of chert, hematite, sphalerite, chalcopyrite, pyrite and barite. Theclastic component is dominantly tuff that has been altered to chlorite and sericite. The MainContact Tuff at Millenbach (Kalogeropoulos and Scott, 1989) consists of bands of tuff (elasticcomponent) alternating with bands of suiphide (chemical component). The tuffaceous materialconsists of quartz, chlorite and sericite; sulphide bands contain pyrite, quartz, sphalerite,pyrrhotite and chalcopyrite. The Key Tuffite in the Matagami mining district (Liaghat andMacLean, 1992) contains 40% tuff from several volcanic sources; the chemical componentconsists of 20% chert and 20% sulphides. The Key Tuffite also contains elevated amounts ofPb,Co, Ni and Cr. The chert-carbonate-suiphide unit at Windy Craggy, northwestern BritishColumbia (Peter, 1989; Robinson and McCarthy, 1991), is 0.1 to 3 m thick and occursdiscontinuously above and peripheral to massive sulphide lenses at Windy Craggy and otherdeposits in the area. The unit is thinly bedded to laminated; individual bands are grey to red. Theelastic component contains radiolaria (Robinson and McCarthy, 1991), chloritized mafic tuff andargillaceous material. The chemical component is a mixture of chert, iron carbonates, white toblack calcite, hematite, rhodonite, magnetite, pyrrhotite, pyrite and chalcopyrite. Exhalites atHidden Creek Anyox mining camp (McDonald et al., 1994) are thinly bedded to laminated white,grey, pale red and green. They consist primarily of white-grey chert with interbedded sulphidesand tuff. The sulphide component is mostly pyrrhotite with lesser pyrite and chalcopyrite. Thetuffaceous component is altered to sericite with lesser biotite and chlorite.This review of ancient exhalites emphasizes that they are mineralogically and chemicallycomplex. On the other hand, Battle zone cherts only contain a minor tuff and sulphidecomponent, but up to 96% SiO2. While this does not exclude an exhalative origin for some of thesilica, one would expect a more complex assemblage from the hydrothermal system responsiblefor depositing the massive sulphide lens. In particular, a higher component of iron bearingminerals such as pyrite or hematite ought to be present. A more likely origin is that rhyolite tuffdeposited on the main Battle massive suiphide lens during the onset of felsic volcanism had a silicacomponent added directly or indirectly from hydrothermal solutions.8.2.2 LithogeochemistiyLithogeochemical and petrographic analyses of least altered rocks from the Price formationand H-W horizon rhyolite support the following conclusions:1. Lavas in the Price andesite are comagmatic and are related by sorting of plagioclasefeldspar, pyroxene, olivine and Fe-Ti oxides (see also Juras, 1987).2. The quartz porphyritic rhyolite (QP), quartz feldspar porphyritic rhyolite (QFP) andgreen quartz feldspar porphyritic rhyolite (GQFP) units of the rhyolite flow domecomplex are comagmatic and are related by sorting of quartz, anorthite and alkalifeldspar. The rhyolite dike (QFPD) is genetically unrelated to the rhyolite flow domecomplex.The significance of olivine fractionation in the Price andesite is not apparent by inspectionof the phenocrysts present, which include plagioclase and clinopyroxene with lesser magnetite.However, aphase discrimination diagram (Russell and Nicholls, 1988) with axes [3M-4Ca+6(Fe+Mg)]/Zr versus Si/Zr (C. Stanley, personal communication, 1994; Figure 4.6d) clearlyshows that phases other than clinopyroxene and feldspar are contributing to chemical variations inthis unit. It is likely that sorting of olivine occurred prior to eruption of the Price formation lavas.Sorting of quartz and feldspar in the QP, QFP and GQFP units of the rhyolite flow-dome complexis documented petrographically in Chapter 3.8.3 ALTERATION1Alteration in the Battle zone consists of a sericite-pyrite-quartz assemblage in the footwall(Price andesite) whereas the hangingwall is sericitized with only minor addition of quartz abovethe chert layer. The following conclusions are significant:1. The center of the alteration zone is marked by addition of silica in both the footwall andimmediate hangingwall (Figure 5. 8a), as well as addition of iron in the footwall (Figure5.8e). Minerals that correspond to the chemical zonation are quartz and pyritestringers in the core of the footwall alteration zone. The “core” of the hangingwallalteration zone is represented by a layer of chert.2. A broader zone of sericitization that occurs both above and below the orebody (Figure5.8c) corresponds to loss ofNa and Ca, and addition of K, Ba (Figure 5.8d) and Rb.Magnesium and Ca that occur in chlorite and carbonate, respectively, do not show anysystematic spatial trends.3. Sericite in the footwall alteration zone has the formula (electron microprobe analyses inTable 5.8):K088Na0B01A12(M078Fe05MgSi3 12)01 o(OH)2.4. Sericite from the hangingwall alteration zone has the formula (electron microprobeanalyses in Table 5.8): K082Na1Ba003A1(Al78MgSi3 12)010(OH)2.Based on these results, the best exploration parameter for alteration appears to be the Nadepletion and K-Ba-Rb addition anomaly surrounding the ore deposit. Further study, however,will be required to determine the extent of this anomaly, so that reasonable estimates of theintensity of alteration with distance to the ore zone may be made. The marked addition of Si andFe in the most intense part of the alteration zone is also usefhl, particularly in evaluating drill holesthat “just missed” intersecting the ore lens. Depletion of Ca more or less corresponds to Nadepletion, but late carbonate alteration can result in spurious Ca anomalies that should be assessedwith caution. Addition ofMg is not related clearly to hydrothermal alteration in the Battle zone(Figure 5.8f).23jAlteration associated with formation of the main Battle massive suiphide lens most likelywas part of the same overall hydrothermal system responsible for the giant H-W lens, the copperrich Trumpeter zone, and possibly, the Gap zone. Hangingwall alteration in the Battle zone isintense. This is in contrast to felsic rocks overlying the giant H-W lens, which are relativelyunaltered. Although the hydrothermal system appears to have become inactive before depositionof felsic volcanics around the H-W mine, this was not the case in the Battle zone. In some areasthe hydrothermal system in the Battle zone established feeder zones through the overlying felsicvolcaniclastics and deposited upper zone massive suiphide lenses. Exhalative sulphide depositionstopped when the quartz feldspar porphyritic (QFP) rhyolite flow buried the system, althoughcontinued hydrothermal activity almost completely sericitized the overlying QFP.8.4 MASSIVE SULPHIDE LENSES AND METALLOGENY8.4.1 Massive suiphide lensesMassive suiphide lenses in the Battle, Gap and upper zones are a representative subset oflenses that illustrates relationships between mineralized intervals in H-W horizon throughoutmuch of the Buttle Lake mining camp. Important relationships are:1. The Battle lens is zoned from a laterally extensive footwall stringer zone in the Priceandesite upwards through: (i) a pyrite and chalcopyrite rich core, (ii) sphalerite withpyrite/chalcopyrite bands in the central region, and (iii) pale yellow sphalerite at the topand periphery. Minor tennantite is present in all zones.2. Gap massive suiphides are zoned from: (i) pyritic footwall stringers in both quartzporphyritic rhyolite and andesite, (ii) pyrite-chalcopyrite massive suiphides withsignificant amounts of bornite, anilite (Cu7S4),tetrahedrite and sphalerite, and (iii)baritic massive suiphides with sphalerite, tetrahedrite and galena.3. The Gap lens contains the germanium bearing suiphides colusite and renierite. Colusitealso contains vanadium.4. Upper zone lenses represent a second cycle of massive suiphide mineralization thatoccurred above the main Battle massive suiphide lens after deposition of the rhyolitetuffaceous sediments. Upper zone sulphides are grossly zoned upwards from: (i) apolymetallic stringer zone in the underlying rhyolite tuffaceous sediments, (ii) massivesuiphides containing sphalerite, pyrite, tennantite and galena, and (iii) a locally presentbarite-sphalerite cap.5. The main Battle massive suiphide lens displays a number of consistent mineralogicaland textural trends with depth to the footwall (Figure 6.4). These include: (i) welldeveloped zoning from Zn to Fe-Cu to Fe suiphides, (ii) decrease in the number ofinclusions in pyrite, and (iii) an increase in grain size.Metal zoning has been documented for many ancient volcanogenic deposits (Large, 1992;Franklin, 1981; Lydon, 1984, and references therein), and thermodynamically modeled byOhmoto et a!. (1983). Current research on seafloor deposits shows that three main processesinvolved in sulphide mound growth are (Fouquet et at., 1993): (i) deposition of primary sulphideduring mixing of hot solutions with seawater, (ii) leaching of older sulphides and concentration ofPb, Ba, Zn at the upper parts of the mound, and (iii) replacement of surficial Fe-Zn assemblagesby coarse pyrite and chalcopyrite during mound growth. This process, originally described forancient deposits by Eldridge et a!. (1983), has been termed, here, progressive zone replacement.Progressive zone replacement is proposed as the most likely mechanism for producing themassive suiphide textures observed in the Battle zone. Furthermore, it was demonstrated thatreplacement preferentially occurred subparallel to bedding as defined in the overlying volcanicpackage. The origin of banding in massive sulphides is enigmatic, but recent mapping by Fouquetet at. (1993) in the Hine Hina hydrothermal field showed that when a hydrothermal system isZ33sealed by a hardened sedimentary crust, higher temperature fluids circulate horizontally below thehardened sediments and cause massive Cu-Fe sulphides to precipitate as horizontal layers beneaththe crust. In the Battle zone, chert and silicified felsic volcanic ash could have acted as a cap tothe hydrothermal system that would have directed lateral fluid flow.Suiphide textures similar to those observed in the Battle and Gap zones could alternativelybe interpreted as metamorphic textures. However, a metamorphic origin for sulphide textures inthe Battle and Gap does not explain: (i) the almost complete absence of primary suiphidetextures, or (ii) the systematic increase in degree of recrystallization with depth to the footwall. Ifthe textures were due to metamorphism, local enclaves with primary sulphide textures such asthose described in Rona et al. (1993) ought to be preserved (Frater, 1985; Drown and Downs,1990; Robinson and McCarthy, 1990). Progressive zone replacement is a more likely originbecause it allows for the (almost) total destruction of primary suiphides, and explains theremarkable degree of metal zoning achieved in many of the Buttle Lake deposits, particularly theBattle zone.8.4.2 Metallogeny and Lead IsotopesThe following conclusions are specific to the galena lead isotope study of the Buttle Lakemining camp.1. Galena lead isotope ratios represent a mixture of upper crustal and mantle leads. Thisis typical of orogene or island arc lead (Figure 7.3).2. Statistical analysis of data from all samples shows that it can be divided into threeclusters (albeit one cluster is a single point) along an apparent mixing line (clusters 1 to3; Figures 7.4 and 7.5) that does not reflect age differences.3. It is argued that: (i) the end-member representing the most radiogenic galena lead onthe mixing line represents either lead selectively leached from the volcanic rocks or leadfrom andesite with a different isotope composition, and (ii) the other, less radiogenicZ9end-member represents lead magmatically derived, and/or leached from dominantlyrhyolitic rocks.4. Differences in lead isotope ratios exist among different ore lenses in the Buttle Lakemining camp. The lead isotope ratios of the largest lenses have a relatively radiogenicsignature (Figure 7.5; cluster 3) compared to the smaller lenses to the north and upperzone type mineralization (Figure 7.5; cluster 2).5. The sample from the ore clast breccia has a unique isotopic composition compared todata from other lenses. The implication is that a system of lenses closely related torhyolite volcanism remains to be discovered.Galena lead isotope ratios can be used to help prioritize exploration for ore lensesthroughout the Buttle Lake mining camp. In H-W horizon, markedly radiogenic lead (Figures 7.4and 7.5; cluster 3) is characteristic of deposits that define the main lens trend (i.e. the H-W andBattle main lenses). As lenses in this trend are among the largest, they are the most attractiveexploration target. Comparatively primitive lead isotopic signatures (Figures 7.4 and 7.5; cluster2) are characteristic of lenses that are associated with rhyolite in the footwall (i.e. Battle upperzone and H-W upper zinc lenses) or of lenses that may have had a contribution of lead fromrhyolite magmatic fluid (i.e. Gap and perhaps some of the H-W North Bornite lenses). Lenses ofthis type are smaller than those in the main lens trend, but can be comparatively enriched inprecious and base metals.REFERENCESAllen, R. 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(1969): Upper Paleozoic Stratigraphy of Vancouver Island, British Columbia;Geological Association ofCanada, Proceedings, volume 20, pages 3 0-40.Yui, S. (1983): Textures of Some Japanese Besshi-Type Ores and Their Implications for KurokoDeposits; Economic Geology, Monograph 5, pages 231-240Zartman, R.E. and Doe, B.R. (1981): Plumbotectonics - The Model, in R.E. Zartman and S.R.Taylor (editors), Evolution of the Upper Mantle, Tectonophysics, volume 75, pages 135-162.APPENDIX ALITHOGEOCREMICAL SAMPLING AND ERRORSSamples for whole rock and trace element analysis were systematically collected fromSection 15+85E and 17+98E. The objective was to sample the full range from least altered up tointensely altered rocks in order to characterize lithogeochemical variation due to primary rockforming processes (Chapter 4) and post depositional metasomatism (Chapter 5). Section 15+98was sampled by A. Hamilton in 1992. His procedure was to sample the internal part of alithologic unit over a 1 to 5 metre interval by splitting the core and sampling every other piece.Section 17+98 was sampled by the author in 1993. To minimize the possibility of sampling over alithological boundary, continuous core samples between 15 and 30 cm long were selected fromthe center of a lithologic interval. Additional samples from other sections and drill holes 14-757and 14-720 were also taken by the author.All the rock samples were jaw crushed at The University of British Columbia (UBC).Fragmental rock types were then inspected for exotic clasts. Where present, these were removedfrom the sample to ensure that the sample was lithologically homogeneous. Samples were thenreduced to less than 200 mesh by grinding in Cr-steel ring mills. The first batch was analyzed atX-Ray Assay Laboratories, Don Mills, Ontario; the second and third batches were analyzed atGeochemical Laboratories, Earth and Planetary Sciences, McGill University, Montreal, Quebec.Selected samples were also analysed for REE at Activation Laboratories, Ancaster, Ontario.Analytical details and detection limits for all analyses are in Table A. 1.Analytical precision was monitored by removing non-essential samples and inserting anMDRU internal standard with the same number as the non-essential sample. The standards usedwere P1, WP 1, MBX 1 and QGRM 100. Analyses of the standards were compiled by A. Toma(Table A.2). The mean, standard deviation (St. Dev.), standard error of the mean (Std. err.mean.) and relative precision in % (Rel Prec.) are reported for each set of duplicate analyses. Theoverall relative precision (in %) for each element is in boldface text at the bottom of Table A.2,2L,and is the average of the relative precision for each element. Precision of XRF analyses is betterthan 2% for major elements except K20, which is precise to within about 5%. Errors for traceelement analyses are variable. The transition elements Cr, V and Zn have acceptable errors of lessthan 10%. Cr values for siliceous units are suspect due to probable contamination during sampleprocessing. Ni, Co and Cu and Pb have errors between 20 and 70%. Trace elements Ba, Rb, Sr,Zr, Th and U have acceptable errors between 4 and 12%. Other trace elements, particularly Yand Nb have unacceptably high errors of 30-40%Within unit variability was assessed by taking duplicates of five rock samples. Analyses foreach pair of samples were averaged and the mean, standard deviation (St. Dev.), standard error ofthe mean (Std. err. mean.) and relative precision in % (Rel. precision.) calculated (Table A.3). Ingeneral, within unit variability is more significant than the analytical precision.TABLE A. 1. DETECTION LIMITS AND ANALYTICAL METHODS FOR THE LITHOGEOCHEMICALANALYSES REPORTED IN CHAPTERS 4 AND 5.Element Method Mount Units Det. Method Mount Units Det. Method Mount Units Det.1 2 Lim 1 2 Lim 1 2 LimBatch 1: X-Ray Assay Batch 2: Geochemical Batch 3: Activation LaboratoriesLaboratories Laboratories LTDSi02 XRF Disk wt % 0.01 XRF Bead ppm 60Ti02 XRF Disk wt % 0.01 XRF Bead ppm 35A1203 XRF Disk wt % 0.01 XRF Bead ppm 120Fe203 XRF Disk wt % 0.01 XRF Bead ppm 30MnO XRF Disk wt % 0.01 XRF Bead ppm 30MgO XRF Disk wt% 0.01 XRF Bead ppm 95CaO XRF Disk wt % 0.01 XRF Bead ppm 15Na20 XRF Disk wt % 0.01 XRF Bead ppm 75K20 XRF Disk wt % 0.01 XRF Bead ppm 25P205 XRF Disk wt % 0.01 XRF Bead ppm 35LOT XRF Disk wt% 0.01 XRF Bead ppm 100Cr XRF Bead ppm 2Ni XRF Bead ppm 3Co XRF Bead ppm 10V XRF Bead ppm 10Cu XRF Pellet ppm 2 XRF Bead ppm 15Pb XRF Pellet ppm 2 XRF Bead ppm 2.0Zn XRF Pellet ppm 2 XRF Pellet ppm 2Ga XRF Pellet ppm 1.0S XRF Pellet ppm 50As INAA ppm 1Sc XRF Pellet ppm 10 INAA ppm 0.1Sb INAA ppm 0.1Au INAA ppb 2Ba XRF Pellet ppm 10 XRF Bead ppm 50 INAA ppm 20Rb XRF Pellet ppm 10 XRF Pellet ppm 1.0 INAA ppm 10Sr XRF Pellet ppm 10 XRF Pellet ppm 1.0 INAA wt % 0.01Nb XRF Pellet ppm 2 XRF Pellet ppm 1.0 INAAZr XRF Pellet ppm 3 XRF Pellet ppm 1.0 INAAY XRF Pellet ppm 2 XRF Pellet ppm 1.0 II”TAATh XRF Pellet ppm 2 XRF Pellet ppm 1.0 INAA ppm 0.1U XRF Pellet ppm 1.0 INAA ppm 0.1Cs INAA ppm 0.2Hf INAA ppm 0.2La INAA ppm 0.1Ce XRF Pellet ppm 1.0 INAA ppm 1Nd INAA ppm 1Sm INAA ppm 0.01Eu INAA ppm 0.05m INAA ppm 0.1Yb INAA ppm 0.05INAA ppm 0.011 XRF = x-ray fluorescence, INNA = neutron activation analysis2 disk = fhsed disk, bead = glass bead, pellet = pressed pelletTABLE A.2. DUPLICATE ANALYSES OF MDRU STANDARDS P1, WP1, MBX 1 AND QGRM 100.Sample Si02 Ti02 P.1203 Fe203 MnO MgO CaO Na20 K20 P205 L0IStd.P1 % % % % % % % % % %ATISK91-02 70.4 0.388 14.4 3.74 0.09 1.09 3.57 4.04 2.02 0.09 0.31ATISK91-06 70.2 0.402 14.4 3.79 0.09 1.15 3.61 4.09 1.93 0.09 0.47BDM91-B19 69.9 0.401 14.4 3.83 0.09 1.13 3.62 4.01 1.97 0.09 0.62D91-181 70 0.411 14.5 3.84 0.09 1.13 3.6 3.95 1.92 0.09 0.47PF3 69.8 0.414 14.2 3.78 0.09 1.15 3.67 4.07 2 0.09 0.457W 69.80 0.41 14.20 3.89 0.09 1.12 3.67 4.11 2.05 0.09 0.4519W 69.30 0.40 14.10 3.85 0.09 1.09 3.62 3.96 2.02 0.09 0.85AJM-1SK92-122 69.7 0.406 14.4 3.86 0.09 1.08 3.61 4.14 2 0.09 0.63-9-9 70.3 0.399 14.4 3.79 0.09 1.1 3.59 3.99 2.1 0.09 0.4Mean 69.93 0.40 14.33 3.82 0.09 1.12 3.62 4.04 2.00 0.09 0.51StDev 0.34 0.01 0.13 0.05 0.00 0.03 0.03 0.07 0.06 0.00 0.16Std. err. mean 0.11 0.00 0.04 0.02 0.00 0.01 0.01 0.02 0.02 0.00 0.05N 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00ReiPres. 0.48 2.11 0.92 1.23 0.00 2.38 0.92 1.67 2.82 0.00 31.66Std. WP1ATISK91-1 64.7 0.511 16.6 4.4 0.09 2.66 5.17 4.31 1.56 0.18 0.08ATISK91-05 63.3 0.515 16.4 4.34 0.09 2.76 5.17 4.36 1.52 0.18 0.23BDM91-B16 64.1 0.52 16.5 4.48 0.09 2.68 5.14 4.44 1.47 0.18 0.31D91-180 64.2 0.522 16.5 4.42 0.09 2.64 5.12 4.32 1.51 0.18 0.31TA2 64.1 0.525 16.5 4.4 0.09 2.73 5.18 4.41 1.59 0.18 0.3516W 63.1 0.51 16.2 4.5 2.68 5.21 4.3 1.56 0.19 0.140W 63.9 0.52 16.4 4.48 2.67 5.21 4.24 1.5 0.18 0.2AJM-1S1C92-121 64.3 0.514 16.6 4.37 0.09 2.63 5.08 4.42 1.57 0.18 0.211-9-1 64.1 0.511 16.4 4.38 0.09 2.6 5.06 4.39 1.69 0.18 0.2Mean 63.98 0.52 16.46 4.42 0.09 2.67 5.15 4.35 1.55 0.18 0.22StDev 0.49 0.01 0.12 0.06 0.00 0.05 0.05 0.07 0.06 0.00 0.09Std.err.mean 0.16 0.00 0.04 0.02 0.00 0.02 0.02 0.02 0.02 0.00 0.03N 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00Rd Pres. 0.77 1.06 0.75 1.26 0.00 1.84 1.04 1.52 4.15 1.84 42.03Std. MBX IBDM91-P23 57.6 0.502 17.6 3.99 0.08 2.09 3.91 5.16 4.37 0.25 3.77D91-179 58.6 0.507 17.7 4.08 0.08 2.15 3.86 5.1 4.33 0.25 3.39AN-2 56.9 0.51 17.3 3.89 0.08 2.09 3.87 5.14 4.48 0.25 3.25AJM-1SK92-112 58.4 0.501 17.7 4.01 0.08 2.06 3.87 5.2 4.51 0.25 3.572W 59.30 0.51 17.90 4.22 0.08 2.13 4.00 4.95 4.18 0.26 0.5537W 59.60 0.51 18.00 4.20 0.08 2.13 4.02 5.07 4.22 0.26 1.65TC92-1006 57.5 0.483 17.5 3.95 0.08 2.03 3.73 5.16 4.5 0.25 3.55Mean 58.27 0.50 17.67 4.05 0.08 2.10 3.89 5.11 4.37 0.25 2.81StDev 0.99 0.01 0.24 0.12 0.00 0.04 0.10 0.08 0.13 0.00 1.22Std. err, mean 0.35 0.00 0.08 0.04 0.00 0.02 0.03 0.03 0.05 0.00 0.43N 8.00 8.00 8.00 8.00 8.00 8.00 8.00 8.00 8.00 8.00 8.00ReiPres. 1.70 2.02 1.34 3.08 0.00 2.04 2.49 1.62 3.08 1.93 43.43Std. QGRM 100BDM9I-E48 48.8 1.97 15.5 15.2 0.19 5.76 8.53 2.83 1.04 0.19 0.39D91-176 48.4 1.99 15.2 15.2 0.19 5.7 8.42 2.79 0.98 0.19 0.1673W 49.00 2.02 15.30 15.30 0.19 5.71 8.77 2.82 1.10 0.20 0.0039W 48.00 2.00 15.10 15.00 0.19 5.60 8.56 2.73 1.01 0.19 0.00AJM-1SK92-110 48.7 2.01 15.6 14.8 0.19 5.54 8.35 2.81 1.03 0.19 0.23-9-3 48.4 1.94 15.4 14.4 0.19 5.42 8.42 2.78 1.2 0.2 0Mean 48.55 1.99 15.35 14.98 0.19 5.62 8.51 2.79 1.06 0.19 0.13StDev 0.36 0.03 0.19 0.34 0.00 0.13 0.15 0.04 0.08 0.01 0.16Std. err. mean 0.12 0.01 0.06 0.11 0.00 0.04 0.05 0.01 0.03 0.00 0.05N 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00 9.00Rd Pres. 0.73 1.47 1.22 2.25 0.00 2.26 1.76 1.29 7.48 2.67 125.96Precision 0.92 1.67 1.06 1.96 0.00 2.13 1.55 1.53 4.38 1.61 60.77TABLE A.2. ANALYTICAL PRECISION...CONTINUEDSampleStd. P1ATISK9 1-02ATISK9 1-06BDM9L-B19D91-181PF357W19WA!M-1SK92-1223-9-9MeanStDevStd. cir. meanNRe! Pres.Std. WPIATISK91-1ATISK9I-05BDM9 1-B 16D91-180TA216W40WAJM-1SK92-12111-9-IMeanStDevStd. err, meanNRe! Pres.Std. MBX IBDM91-P23D91-179AN-2AJM-1SK92-1 1272W37WTC92-1006MeanStDevStd. err, meanNRet Pres.Std. QGRM 100BDM91-E48D91-17673W39WAJM-1SK92-1 103-9-3MeanSlDevStcL err, meanNRel Pres.PrecisionS As Scppm ppm ppm50 0.4 10.450 0.05 10100 0.5 9.92140 1 10.770 1 10.380 0.6 10.950 0.3 9.5677.14 0.55 10.1833.52 0.35 0.4811.17 0.13 0.159.00 7.00 10.0043.46 64.07 4.71110 0.6 9.4170 1 8.8776.25 0.61 9.0526.69 0.21 0.359.44 0.08 0.138.00 7.00 7.0035.01 34.44 3.88Cr Ni Co V Cu Pb Zn Gappm ppm ppm ppm ppm ppm ppm ppm120 4 10 61 10.8 1 44.0130 4 6 72 11.3 1 41.3130 2 4 54 7.9 1 42.6130 0.5 5 55 7 1 43.7140 3 4 61 8.3 1 45.21 9 521 10 53120 1 6 62 8.6 1 43.9130 2 6 60 8.2 1 40.7128.57 2.31 5.88 61.88 7.35 2.70 44.886.90 1.28 1.89 6.36 3.59 3.59 4.242.61 0.45 0.67 2.25 1.14 1.14 1.347.00 8.00 8.00 8.00 10.00 10.00 10.00 0.005.37 55.35 32.09 10.27 48.84 133.02 9.4467 40 15 84 18.3 1 6266 38 8 95 15.9 1 52.360 39 7 72 15.5 1 56.765 41 9 74 14.3 1 56.675 43 8 81 15 1 60.16 2 6010 6464 39 12 74 15 1 56.567 37 10 95 14.9 1 54.966.29 39.57 9.86 82.14 13.88 1.13 58.124.54 1.99 2.79 9.75 3.66 0.35 3.681.60 0.75 1.06 3.69 1.22 0.13 1.238.00 7.00 7.00 7.00 9.00 8.00 9.00 0.006.84 5.02 28.35 11.87 26.37 31.43 6.33505010011070500.3 9.190.6 8.940.5 9.030.7 8,450.6 9.4839 6 3 136 421 1 29.6 2300 4.9 6.8144 5 3 156 446 1 30.4 2200 5 6.7444 7 3 172 422 1 29.8 2090 5.2 6.6835 5 7 177 418 1 28.2 5.2 6.59329 1 37 941327 1 39 101039 5 7 162 467 1 27.3 2190 4.6 6.5740.20 5.60 4.60 160.60 404.29 1.00 31.61 1788.50 4.98 6.683.83 0.89 2.19 16.02 54.92 0.00 4.52 633.62 0.25 0.101.57 0.37 0.89 6.54 19.42 0.00 1.60 0.00 239.49 0.10 0.046.00 6.00 6.00 6.00 8.00 8.00 8.00 1.00 7.00 6.00 6.009.54 15.97 47.63 9.98 13.58 0.00 14.30 35.43 5.00 1.5177 45 40 216 134 1 125 1700 1.8 28.284 42 42 201 129 1 111 1800 3.3 27.194 11 109 132096 7 108 135078 39 42 200 132 1 100 1550 1.8 25.684 40 43 207 143 1 116 1670 1.8 26.880.75 41.50 41.75 206.00 121.33 3.67 111.50 1565.00 2.18 26.933.77 2.65 1.26 7.35 20.93 4.32 8.41 195.42 0.75 1.071.43 1.00 0.48 2.78 6.98 1.44 2.80 0.00 65.14 0.28 0.407.00 7.00 7.00 7.00 9.00 9.00 9.00 3.00 9.00 7.00 7.004.67 6.38 3.01 3.57 17.25 117.83 7.54 12.49 34.48 3.976.61 20.68 27.77 892 26.51 70.57 9.40 31.59 34.50 3.52TABLE A.2. ANALYTICAL PRECISION...CONTINUED45LSample Sb Au Ba Rb Sr Nb Zr Y Th U Cs LaStd.P1 ppm ppb ppm ppm ppm ppm ppm ppm ppm ppm ppm ppmATISK91-02 3 0.5 887 47 228 5 126 18 4 1.4 1 13.7ATISK9L-06 0.2 0.5 898 47 273 5 116 18 4.2 1.6 1 13.8BDM91-B19 0.3 7 895 45 266 2 117 29 4.3 1.5 1 13D91-181 0.2 0.5 903 47 282 3 147 27 3.9 1.6 1 12.7PF3 0.3 6 833 48 288 12 115 18 4 1.6 1 13.657W 822 64 15 141 519W 784 61 248 133 5AJM-1SK92-122 0.3 0.5 868 46 274 7 126 17 3.9 1.6 1 14.13-9-9 0.2 0.5 757 45 260 7 132 15 3.9 1.3 1 13.5Mean 0.64 2.21 849.67 50.00 264.88 7.00 128.11 19.88 4.24 1.51 1.00 13.49St. Dcv. 1.04 2.94 53.51 7.19 19.45 4.44 11.25 5.14 0.45 0.12 0.00 0.45Std.err.mean 0.35 1.11 17.84 2.40 6.88 1.57 3.75 1.82 0.15 0.05 0.00 0.16N 9.00 7.00 9.00 9.00 8.00 8.00 9.00 8.00 9.00 7.00 7.00 8.00Rd Pres. 161.87 132.86 6.30 14.39 7.34 63.43 8.78 25.86 10.61 8.02 0.00 3.30Std. WP 1ATISK9I-1 3.8 0.5 703 25 726 13 119 13 2 0.9 1 13.6ATISK91-05 0.1 3 678 22 905 5 122 12 1.8 0.4 0.5 13.6BDM9L-B16 0.2 0.5 676 23 880 1 134 20 1.9 0.8 0.5 13.4D91-180 0.1 2 707 22 888 4 123 26 2.1 0.8 0.5 14.9TA2 0.1 2 655 26 859 12 120 12 2 0.9 0.5 14.716W 612 26 815 9 135 240W 573 28 850 8 135AJM-15K92-121 0.2 0.5 632 22 843 6 134 11 1.8 1 1 1411-9-1 0.1 0.5 560 22 851 8 144 11 1.8 0.8 0.5 14.7Mean 0.66 1.29 644.00 24.00 846.33 7.33 129.56 15.00 1.93 0.80 0.64 14.13St. Dcv. 1.39 1.04 53.64 2.29 52.42 3.81 8.73 5.77 0.12 0.19 0.24 0.63Std. ei. mean 0.52 0.39 17.88 0.76 17.47 1.27 2.91 2.18 0.04 0.07 0.09 0.24N 7.00 7.00 9.00 9.00 9.00 9.00 9.00 7.00 8.00 7.00 7.00 7.00Ret Pres. 211.02 80.51 8.33 9.55 6.19 51.93 6.74 38.49 6.05 23.94 37.95 4.43Std. MBX IBDM91-P23 3.5 79 842 79 636 6 95 13 3 0.6 2 14.7D91-179 3.2 57 880 80 640 9 93 25 2.8 0.8 3 16.9AN-2 3.2 52 736 78 607 19 95 9 2.4 0.4 3 14.6AJM-1SK92-112 3.2 88 790 76 585 14 101 8 2.6 0.8 2 14.572W 771 87 609 14 10137W 728 79 600 12 106TC92-1006 3 38 658 75 599 13 112 8 2.5 0.6 3 16.3Mean 3.22 62.80 772.14 79.14 610.86 12.43 100.43 12.60 2.66 0.64 2.60 15.40St. Dcv. 0.18 20.39 74.29 3.89 20.11 4.12 6.83 7.23 0.24 0.17 0.55 1.12Std.err.mean 0.07 8.32 26.27 1.38 7.11 1.46 2.41 2.95 0.10 0.07 0.22 0.46N 6.00 6.00 8.00 8.00 8.00 8.00 8.00 6.00 6.00 6.00 6.00 6.00Ret. Precision 5.56 32.47 9.62 4.92 3.29 33.13 6.80 57.40 9.05 26.15 21.07 7.26Std. QGRM 100BDM91-E48 0.3 18 249 29 239 4 137 31 2 0.9 0.5 12.6D91-176 0.3 13 248 26 231 7 160 21 2.2 1 1 12.273W 261 35 229 8 145 239W 180 23 233 7 143 3AJM-15K92-110 0.4 20 176 28 245 7 142 28 1.9 0.9 0.5 13.33-9-3 0.4 14 167 25 230 8 150 29 1.8 0.8 1 12.9Mean 0.35 16.25 213.50 27.67 234.50 6.83 146.17 27.25 2.15 0.90 0.75 12.75St. Dcv. 0.06 3.30 43.35 4.18 6.25 1.47 7.99 4.35 0.44 0.08 0.29 0.47Std. err. mean 0.02 1.25 14.45 1.39 2.08 0.49 2.66 1.64 0.15 0.03 0.11 0.18N 7.00 7.00 9.00 9.00 9.00 9.00 9.00 7.00 9.00 7.00 7.00 7.00Ret Precision. 16.50 20.33 20.31 15.11 2.67 21.54 5.46 15.96 20.33 9.07 38.49 3.65Precision (% 98.73 66.54 11.14 10.99 4.87 42.51 6.95 34.43 11.51 16.79 24.38 4.66“) r’4JTABLE A.2. ANALYTICAL PRECISION...CONTINUEDSampleStd. P1ATISK91-02ATJSK9 1-06BDM91-B19D91-181PF357W19WAJM-1SK92-1223-9-9MeanSt Dcv.Std. err. meanNRel. Precision.Std. WP IATISK91-1ATISK91-05BDM9L-B16D91-180TA216W40WAJM-1SK92-12111-9-1MeanSt. Dcv.Std. err, meanNRd. Precision.Std. MBX IBDM91-P23D91-179AN-2AJM-1SK92-1 1272W37WTC92-1006MeanSt. Dcv.Std. err, meanNRd. Precision.Std. QGRM 10013DM91-E48D91-17673W39WAJM-1SK92-1 103-9-3MeanSt. Dcv.Std. en’. meanNRd. PrecisionPrecision (%‘)Ce Pr Nd Sm Eu Gd Thppm ppm ppm ppm ppm ppm ppm26 2.9 12.9 2.6 0.78 2.1 0.327.2 3.1 12.7 3 0.77 2.8 0.525.4 3.2 13.8 2.9 0.9 2.9 0.525.1 3.4 15.4 3 0.92 3 0.525.6 3.1 13.1 3.2 0.73 3.5 0.528.6 3 12.1 2.7 0.87 2.9 0.426.5 3.1 12.5 3.1 1 3.3 0.526.31 3.11 13.29 2.90 0.84 2.95 0.451.13 0.15 1.04 0.21 0.09 0.41 0.080.40 0.05 0.37 0.08 0.03 0.15 0.038.00 8.00 8.00 8.00 8.00 8.00 8.004.31 4.68 7.82 7.37 11.03 14.04 16.8029.9 3.3 13.4 2.8 0.93 2.8 0.330.7 3.8 15.5 3.6 1.1 3.1 0.529.54 3.69 15.86 3.14 0.93 2.83 0.411.36 0.37 1.74 0.44 0.12 0.35 0.090.51 0.14 0.66 0.16 0.05 0.13 0.037.00 7.00 7.00 7.00 7.00 7.00 7.004.60 10.08 11.00 13.85 13.05 12.54 21.72Dy Ho Er Tm Yb Luppm ppm ppm ppm ppm ppm2.9 0.63 1.9 0.3 2 0.343.2 0.61 2.1 0.3 2 0.293.1 0.62 2.1 0.4 2.4 0.343.3 0.66 2.2 0.3 2.2 0.343 0.7 2.3 0.4 2.1 0.352.8 0.55 1.6 0.3 2.1 0.273.2 0.65 2 0.3 1.9 0.33.05 0.63 2.01 0.33 2.10 0.320.18 0.04 0.22 0.05 0.15 0.030.06 0.02 0.08 0.02 0.05 0.018.00 8.00 8.00 8.00 8.00 8.005.81 6.89 10.77 14.24 7.20 9.102.1 0.37 1 0.2 1.2 0.182.8 0.49 1.5 0.2 1.4 0.222.47 0.44 1.46 0.21 1.40 0.220.29 0.04 0.28 0.04 0.13 0.030.11 0.01 0.10 0.01 0.05 0.017.00 7.00 7.00 7.00 7.00 7.0011.61 8.32 18.94 17.64 9.22 15.5227.3 3.3 14.3 2.5 0.85 2.1 0.3 2.3 0.46 1.3 0.2 1.3 0.2529.3 3.4 15.7 2.9 0.77 2.8 0.4 2.3 0.43 1.4 0.2 1.4 0.2128.4 3.7 16 3.1 0.9 2.8 0.4 2.3 0.45 1.6 0.3 1.5 0.1929.9 4.2 18 3.6 1.09 3.1 0.5 2.8 0.45 1.9 0.2 1.6 0.2831.3 4.1 18.1 3.5 0.89 3.1 0.5 2.7 0.45 1.5 0.2 1.4 0.2226.4 3 13 2.8 0.99 2.4 0.3 2 0.35 1.2 0.2 1.1 0.1830.1 3.6 14.3 2.8 0.85 2.3 0.4 2.1 0.51 1.2 0.2 1.2 0.227 3.4 14.2 2.9 0.72 2.3 0.3 1.8 0.35 1.2 0.2 1 0.1827.1 2.7 10.6 2.4 0.84 2.2 0.3 1.5 0.28 0.8 0.1 0.9 0.1328.9 3.4 14.2 3.1 1.06 2.6 0.4 2 0.34 1 0.2 1.1 0.1827.90 3.22 13.26 2.80 0.89 2.36 0.34 1.88 0.37 1.08 0.18 1.06 0.171.54 0.36 1.58 0.25 0.13 0.15 0.05 0.24 0.09 0.18 0.04 0.11 0.030.63 0.15 0.65 0.10 0.05 0.06 0.02 0.10 0.03 0.07 0.02 0.05 0.016.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.005.54 11.28 11.92 9.11 15.03 6.43 16.11 12.70 23.39 16.56 24.85 10.76 14.9930.2 4.8 23.2 4.9 1.82 5.7 0.9 6.3 1.38 4.4 0.6 3.3 0.530 4.6 24.6 6.4 1.95 5.8 1.2 6.8 1.37 4.4 0.6 4.2 0.6231.9 3.8 17.8 4.9 1.59 5.7 0.8 5.4 1.03 2.9 0.4 3.3 0.4229.8 4.2 19.2 5.4 1.79 5.9 1 6.3 1.21 3.6 0.5 3.2 0.4830.48 4.35 21.20 5.40 1.79 5.78 0.98 6.20 1.25 3.83 0.53 3.50 0.510.96 0.44 3.22 0.71 0.15 0.10 0.17 0.58 0.16 0.72 0.10 0.47 0.080.36 0.17 1.22 0.27 0.06 0.04 0.06 0.22 0.06 0.27 0.04 0.18 0.037.00 7.00 7.00 7.00 7.00 7.00 7.00 7.00 7.00 7.00 7.00 7.00 7.003.16 10.19 15.19 13.09 8.33 1.66 17.52 9.40 13.19 18.90 18.24 13.40 16.614.40 9.06 11.48 10.86 11.86 8.66 18.04 9.88 12.95 16.29 18.7410.14 14.05TABLE A.3. DUPLICATE ANALYSES OF ROCK UNITS TO TEST WITHIN-UNIT HOMOGENEITYSample Si02 Ti02 A1203 Fe203 MnO MgO CaO Na20 K20 P205 LOl13W 26.90 0.91 18.40 29.90 0.01 0.56 0.24 0.23 5.47 0.21 17.3014W 30.40 0.94 18.90 27.00 0.01 0.58 0.36 0.24 5.53 0.25 16.10Mean 28.65 0.92 18.65 28.45 0.01 0.57 0.30 0.24 5.50 0.23 16.70Std. dev. 1.75 0.01 0.25 1.45 0.00 0.01 0.06 0.01 0.03 0.02 0.60Std. err. of mean 1.24 0.01 0.18 1.03 0.00 0.01 0.04 0.00 0.02 0.01 0.42Rel. precision 6.11 1.35 1.34 5.10 0.00 1.75 20.00 2.13 0.55 8.70 3.59(%)34W 60.50 0.50 19.20 4.49 0.03 0.92 0.34 0.52 5.06 0.12 4.8533W 59.80 0.51 19.80 4.97 0.03 0.84 0.26 0.42 5.38 0.13 5.10Mean 60.15 0.50 19.50 4.73 0.03 0.88 0.30 0.47 5.22 0.13 4.98Std. dev. 0.35 0.01 0.30 0.24 0.00 0.04 0.04 0.05 0.16 0.01 0.13Std. err. of mean 0.25 0.01 0.21 0.17 0.00 0.03 0.03 0.04 0.11 0.00 0.09Rel. precision 0.58 1.68 1.54 5.07 0.00 4.55 13.33 10.64 3.07 4.00 2.5102W 76.40 0.22 12.10 1.29 0.04 0.43 1.37 3.06 2.12 0.05 1.5501W 73.90 0.25 13.30 1.74 0.03 0.43 1.42 2.86 2.47 0.06 1.90Mean 75.15 0.23 12.70 1.52 0.04 0.43 1.40 2.96 2.30 0.06 1.73Std. dev. 1.25 0.02 0.60 0.22 0.00 0.00 0.02 0.10 0.18 0.01 0.17Std. err. of mean 0.88 0.01 0.42 0.16 0.00 0.00 0.02 0.07 0.12 0.00 0.12Rel. precision 1.66 7.33 4.72 14.85 14.29 0.00 1.79 3.38 7.63 9.09 10.14174WR* 70.21 0.50 12.81 7.02 0.02 0.57 0.35 0.12 3.59 0.14 5.03I7SWR* 71.13 0.42 10.22 8.68 0.02 0.45 0.37 0.00 2.87 0.18 5.61Mean 70.67 0.46 11.52 7.85 0.02 0.51 0.36 0.06 3.23 0.16 5.32Std. dev. 0.46 0.04 1.30 0.83 0.00 0.06 0.01 0.06 0.36 0.02 0.29Std. err, of mean 0.33 0.03 0.92 0.59 0.00 0.04 0.01 0.04 0.25 0.01 0.21Rd. precision 0.65 8.70 11.25 10.57 0.00 11.76 2.78 100.00 11.15 12.50 5.451S7WR 52.70 0.61 15.98 8.61 0.80 7.40 1.21 0.56 2.94 0.18 7.841S6WR 53.12 0.65 16.26 8.02 1.03 7.55 1.71 0.09 3.08 0.18 7.46Mean 52.91 0.63 16.12 8.32 0.92 7.48 1.46 0.33 3.01 0.18 7.65Std. dev. 0.21 0.02 0.14 0.29 0.12 0.08 0.25 0.24 0.07 0.00 0.19Std. err. ofmean 0.15 0.01 0.10 0.21 0.08 0.05 0.18 0.17 0.05 0.00 0.13Rel. precision 0.40 3.17 0.87 3.55 12.57 1.00 17.12 72.31 2.33 0.00 2.48Sample13W14WMeanStd. dev.Std. err. of meanRel. precision(%)TABLE A.3. DUPLICATE ANALYSES OF ROCK UNITS...CONTJNUEDS ppm131000118000124500.006500.004596.195.22Z5Ba.189019101900.0010.007.070.53080.00 1.50 1445.0 16400.00056.57 1.06 1021.7 11596.55717.66 42.86 27.55 48.520105.0074.252.4302W01WMeanStd. dev.Std. err. of meanRel. precision174WR*175WR*MeanStd. dev.Std. err, of meanRel. precision16.61214.302.301.6316.085500.003889.0941.6775.0053.036.126 14926 11956.00 1343.500.00 148.500.00 105.010.00 11.0586 26 43 172 540 45.9 12147195 38 22 156 121 43 940140.50 32.00 32.50 164.00 330.50 44.45 6543.5Cr203 Ni Co V Ga ScCu Pb Zn432 18 106709 11 66570.50 14.50 86.00138.50 3.50 20.0097.93 2.47 14.1424.28 24.14 23.2634W33WMeanStd. dev.Std. err. of meanRe!. precision533373453.002 66905 38003.50 5245.0502001740033800.00421044204315.018700770013200.001 1 311 1 481.00 1.00 39.500.00 0.00 8.500.00 0.00 6.010.00 0.00 21.52332 20 18 82 230 13.1 148368 13 9 72 1452 19 165350.00 16.50 13.50 77.00 841.00 16.05 156.5018.00 3.50 4.50 5.00 611.00 2.95 8.5012.73 2.47 3.18 3.54 432.04 2.09 6.015.14 21.21 33.33 6.49 72.65 18.38 5.43115013001225.00187WR186WRMeanStd. dev. 54.50 6.00 10.50 8.00 209.50Std. err, of mean 38.54 4.24 7.42 5.66 148.1420.916.118.501719 118518.00 1185.00 01.45 5603.5 2.40 1.00 0.0001.03 3962.271.70 0.71 0.00Rd. precision 38.79 18.75 32.31 4.88 63.39 3.26 85.63 12.97 5.56 0.00TABLE A.3. DUPLICATE ANALYSES OF ROCK UNITS...CONTINUEDSample Rb Sr Nb Zr Y Th U Ce13W 71 22 6 64 114W 83 20 8 67 14Mean 77.00 21.00 7.00 65.50 7.50Std. dev. 6.00 1.00 1.00 1.50 6.50Std. err. of mean 4.24 0.71 0.71 1.06 4.60Rel. precision 7.79 4.76 14.29 2.29 86.67(%)34W 74 27 8 157 1833W 79 17 11 160 16 7Mean 76.50 22.00 9.50 158.50 17.00 4.00Std. dev. 2.50 5.00 1.50 1.50 1.00 3.00Std. err, of mean 1.77 3.54 1.06 1.06 0.71 2.12Rel. precision 3.27 22.73 15.79 0.95 5.88 75.0002W 32 68 9 124 5 301W 40 73 9 145 9 6Mean 36.00 70.50 9.00 134.50 7.00 4.50Std. dev. 4.00 2.50 0.00 10.50 2.00 1.50Std. err. of mean 2.83 1.77 0.00 7.42 1.41 1.06Rd. precision 11.11 3.55 0.00 7.81 28.57 33.33174WR* 54.6 35.8 8.2 81 21.5 11 5.1 3017SWR* 36 22.1 8.4 70.4 23 12.8 6.7 29Mean 45.30 28.95 8.30 75.70 22.25 11.90 5.90 29.50Std. dev. 9.30 6.85 0.10 5.30 0.75 0.90 0.80 0.50Std. err. of mean 6.58 4.84 0.07 3.75 0.53 0.64 0.57 0.35Rel. precision 20.53 23.66 1.20 7.00 3.37 7.56 13.56 1.69187WR 35.9 32.9 7.1 65.1 24.9 11.8 8.6 42186WR 39.8 34.9 8.1 68.1 21 8.5 5.5 46Mean 37.85 33.90 7.60 66.60 22.95 10.15 7.05 44.00Std. dev. 1.95 1.00 0.50 1.50 1.95 1.65 1.55 2.00Std. err. ofmean 1.38 0.71 0.35 1.06 1.38 1.17 1.10 1.41Rel. precision 5.15 2.95 6.58 2.25 8.50 16.26 21.99 4.5525OZ57APPENDIX BADDITIONAL SULPHIDE ANALYSES FROM THE GAP LENSTABLE B.1 MICROPROBE ANALYSES FOR OTHER SULPHIDES, GAP MASSIVE SULPHIDELENSM2-2 M2-3 M3-6 M2-7 M1-3 M1-4 M3-7 M3-8Anilite Anilite Bornite Bornite Bomite Bomite Sphalerite SphaleriteWeight %Cu 76.597 76.854 62.354 61.205 61.779 62.225 0.028 0.502Zn 0.000 0.000 0.021 0.000 0.70 0.000 66.758 66.332Ge 0.088 0.02 0.058 0.157 0.03 1 0.061 0.044 0.063As 0.000 0.000 0.000 0.009 0.000 0.04 1 0.000 0.000Sb 0.007 0.000 0.000 0.017 0.000 0.013 0.000 0.026V 0.014 0.000 0.000 0.000 0.018 0.000 0.018 0.000Fe 0.051 0.09 11.290 13.237 10.943 11.328 0.053 0.153S 22.438 22.133 26.393 26.021 25.898 26.031 33.019 33.095Total 99.195 99.097 100.121 100.646 99.3 70 99.737 100.1 100.171

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