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TitleHeavy mineral and geochemical signatures of porphyry copper mineralization: examples from the Casino porphyry Cu-Au-Mo deposit, Yukon
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LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorMcClenaghan, M BORCID logo; McCurdy, M WORCID logo; Garrett, R G; Beckett-Brown, C E; Leybourne, M I; Casselman, S G; Pelchat, P
SourceTargeted Geoscience Initiative 5: contributions to the understanding and exploration of porphyry deposits; by Plouffe, AORCID
logo (ed.); Schetselaar, E (ed.); Geological Survey of Canada, Bulletin 616, 2021 p. 159-202, Open Access logo Open Access
PublisherNatural Resources Canada
Mediaon-line; digital
RelatedThis publication is contained in Targeted Geoscience Initiative 5: contributions to the understanding and exploration of porphyry deposits
File formatpdf
NTS115J/09; 115J/10; 115J/11; 115J/14; 115J/15; 115J/16
AreaCasino Creek
Lat/Long WENS-139.1667 -138.1667 63.0000 62.5000
Subjectseconomic geology; mineralogy; geochemistry; surficial geology/geomorphology; Science and Technology; Nature and Environment; mineral deposits; porphyry deposits; porphyry copper; gold; molybdenum; mineral exploration; exploration methods; heavy mineral analyses; geochemical analyses; stream sediment geochemistry; silts; stream water geochemistry; groundwater geochemistry; mineral assemblages; mineral occurrences; stream sediment samples; size fractionation; mineralogical analyses; bedrock geology; lithology; igneous rocks; intrusive rocks; monzonites; breccias; alteration; chalcopyrite; element distribution; provenance; Casino Deposit; Yukon-tanana Terrane; Intermontane Belt; Canadian Cordillera; alluvial sediments; Phanerozoic; Cenozoic; Quaternary; Tertiary; Mesozoic; Cretaceous; Paleozoic; Permian; Carboniferous; Mississippian; Devonian; Precambrian; Proterozoic
Illustrationsgeoscientific sketch maps; tables; photomicrographs; plots; ternary diagrams
ProgramTargeted Geoscience Initiative (TGI-5) Intrusion/Porphyry ore systems - porphyry processes - mineral markers
Released2021 09 01
AbstractWe report results of a detailed indicator mineral and geochemical study of the Casino calc-alkaline porphyry Cu-Au-Mo deposit in the unglaciated terrain of west-central Yukon. It is one of the largest and highest-grade porphyry Cu-Au-Mo deposits in Canada and is hosted by Late Cretaceous quartz monzonite and associated breccias. At 22 sites, a large (10-14 kg) stream-sediment sample, streamwater and stream silt samples were collected to compare geochemical and heavy mineral signatures. The Casino deposit has an obvious indicator mineral signature in the less than 2 mm heavy (>3.2 specific gravity (SG)) and mid-density (2.8-3.2 SG) fractions of stream sediments that is detectable at least 14 km downstream and consists of, in order of effectiveness, gold>chalcopyrite>molybdenite>sphalerite >jarosite>goethite>pyrite. Similar indicator mineral patterns occur in creeks downstream of other local porphyry occurrences (i.e. Cockfield, Zappa). The geochemical signature of the deposit is best defined by Ag, As, Au, Bi, Cd, Cu, Fe, Mn, Mo, Pb, U, and Zn in the less than 0.177 mm fraction of stream sediment and Cd, Co, Cu, Mo, Pb, Re, and Zn in stream water. Governments and exploration companies will benefit from adding indicator mineral sampling to routine stream-sediment sampling protocols during geochemical surveys in which detailed follow up during the same season is impossible.
Summary(Plain Language Summary, not published)
This Bulletin published by the Geological Survey of Canada contains ten articles summarizing the results of five-year research projects conducted on porphyry deposits in Canada as part of the Targeted Geoscience Initiative (TGI). Porphyry deposits are ore bodies, including past-producing and active mines, associated with intrusive rocks such as granite. They are significant producers of a variety of metals, including copper, molybdenum, tin and tungsten. Nine out of ten papers describe projects conducted in the Canadian Cordillera where most Canadian porphyry deposits occur and a paper on similar, but older deposits in the Appalachians of Atlantic Canada. The main objective of these TGI research projects was to better define the geological conditions where porphyry deposits form and test techniques to detect buried porphyry deposits in support of mineral exploration.

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