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Fluid inclusion and stable isotopic study of precious and base metal veins from the Coeur d'Alene silver-lead-zinc district, Idaho, United States of America

Posted on:2001-05-25Degree:M.ScType:Thesis
University:University of Alberta (Canada)Candidate:Arkadakskiy, Serguey ViktorovFull Text:PDF
GTID:2460390014456393Subject:Geology
Abstract/Summary:
Ag-Pb-Zn veins at the Coeur d'Alene district precipitated from CO 2-undersaturated (XCO2 < 0.04) fluids of moderate to high salinities (9 to 23 eq. wt. % NaCl) and uniform δ18O fluid (8.5 ± 2.4‰; n = 69). Microthermometric data and positive δ18O and δ13C correlation of vein siderite suggest that fluid mixing caused mineral deposition. Calculated δ 13Cfluid (−10.7 ± 2.1‰, n = 45) and δ 34SΣS (4.4 ± 1.6‰, n = 15) indicate carbon and sulphur derivation from oxidation of organic matter, and from leaching of preexisting sulphides of abiogenic or magmatic origin, respectively. Late CO2(N2, CH4)-rich fluids (XCO2 0.14 to 0.23) precipitated unmineralized quartz.; Immiscibility of CO2-rich fluids caused gold deposition in Au-quartz veins in the district. Similar P-V-T-X properties suggest a common origin for the fluids associated with Au-quartz veins and late stage quartz in the Ag-Pb-Zn veins.; In contrast to previous studies suggesting Precambrian age for some Ag-Pb-Zn veins, similar fluid P-V-T-X properties and mineral stable isotopic compositions suggest that all veins studied formed simultaneously possibly during the Mesozoic.
Keywords/Search Tags:Veins, Fluid, District
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