The Werner Lake Co-Cu-Au deposit of the English River Subprovince, Ontario, Canada; evidence for an exhalative origin and effects of granulite facies metamorphism

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doi: 10.2113/gsecongeo.95.8.1635
Authors:Pan, Yuanming; Therens, Craig
Author Affiliations:Primary:
University of Saskatchewan, Department of Geological Sciences, Saskatoon, SK, Canada
Volume Title:Economic Geology and the Bulletin of the Society of Economic Geologists
Source:Economic Geology and the Bulletin of the Society of Economic Geologists, 95(8), p.1635-1656. Publisher: Economic Geology Publishing Company, Lancaster, PA, United States. ISSN: 0361-0128
Publication Date:2000
Note:In English. 75 refs.; illus., incl. sect., 7 tables, geol. sketch map
Summary:The Werner Lake Co-Cu-Au deposit is confined to a mixed unit of orthopyroxene-bearing amphibolites, ultramafic rocks, garnetiferous biotite schists, calc-silicate rocks and garnet-rich quartzite. Mineralization includes disseminated sulphides in the garnetiferous biotite schists and semi-massive to massive cobaltite-rich ore-bodies. Field relationships and geochemical data suggest that the garnetiferous biotite schists were most likely derived from amphibolites, whereas the calc-silicate rocks and garnet-rich quartzites probably represent metamorphosed exhalites. Mass changes for the formation of the garnetiferous biotite schists include gains, Fe, Mn, and K but loses in Ca and Na. The garnetiferous biotite schists are also characterized by depletion in whole-rock δ 18O values (4-6.50/00 V-SMOW) relative to the associated amphibolites (6.8-8.30/00) and ultramafic rocks (5.6-6.60/00), which is interpreted as an indication of high-T interactions with sea-water. Near zero δ 34S values of cobaltite and sulphides indicate a juvenile source for S. Chalcopyrite-rich veins with biotite-rich selvages suggest a local, fluid-facilitated remobilization during retrogression. Granulite-facies metamorphism, deformation and subsequent retrogression might have locally upgraded the cobaltite-rich ores. Late hydrothermal alteration did not significantly affect the Co mineralization in the Werner Lake deposit. [G.L.B.]
Sections:Geochemistry
Subsections:Igneous rocks
Subjects:Cobalt ores; Copper ores; Deformation; Exhalative processes; Facies; Gold ores; Granulite facies; Isotope ratios; Isotopes; Metal ores; Metamorphic rocks; Metamorphism; Mineral deposits, genesis; Mineralization; O-18/O-16; Oxygen; P-T conditions; S-34/S-32; Stable isotopes; Sulfur; Canada; Canadian Shield; Eastern Canada; English River Belt; North America; Ontario; Superior Province; Werner Lake Deposit
Abstract Numbers:03M/4134
Record ID:2001007873
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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