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TitleReconnaissance molybdenum isotope study of vent-distal SEDEX zinc-lead mineralization and host rocks in the Howard's Pass district, Selwyn Basin, Yukon: potential application to paleoredox determinations
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AuthorPeter, J M; Gadd, M G; Layton-Matthews, D; Voinot, A
SourceTargeted Geoscience Initiative: 2018 report of activities; by Rogers, N (ed.); Geological Survey of Canada, Open File 8549, 2019 p. 105-123, https://doi.org/10.4095/313645 (Open Access)
Year2019
PublisherNatural Resources Canada
Documentopen file
Lang.English
Mediaon-line; digital
RelatedThis publication is contained in Rogers, N; (2019). Targeted Geoscience Initiative: 2018 report of activities, Geological Survey of Canada, Open File 8549
File formatpdf
ProvinceYukon
NTS105I
AreaHoward's Pass
Lat/Long WENS-130.0000 -128.0000 63.0000 62.0000
Subjectseconomic geology; geochemistry; stratigraphy; mineral deposits; zinc; lead; sedimentary ore deposits; volcanic exhalitive zone; volcano-sedimentary ore deposits; hydrothermal deposits; mineral exploration; mineral potential; ore mineral genesis; mineralization; ore controls; hydrothermal systems; marine environments; bulk composition; geochemical analyses; isotopic studies; stable isotope studies; molybdenum geochemistry; bedrock geology; lithology; sedimentary rocks; mudstones; shales; sandstones; cherts; carbonates; dolomites; limestones; igneous rocks; volcanic rocks; volcano-sedimentary strata; sulphides; intrusive rocks; monzonites; granites; host rocks; mass spectrometer analysis; drill core analyses; Selwyn Basin; Road River Group; Duo Lake Formation; Earn Group; Mackenzie Platform; Anniv East Deposit; ore systems approach; sedimentary exhalative (SEDEX) deposits; redox indicators; paleoredox indicators; rare earth element (REE) analyses; chemostratigraphy; Phanerozoic; Mesozoic; Cretaceous; Triassic; Paleozoic; Carboniferous; Devonian; Silurian; Ordovician; Cambrian; Precambrian; Proterozoic
Illustrationsschematic models; bar graphs; geoscientific sketch maps; stratigraphic charts; photographs; tables; geochemical plots; geochemical profiles
ProgramKnowledge Management Coordination, Targeted Geoscience Initiative (TGI-5)
ProgramVolcanogenic massive sulphide ore systems - deposition - time and space, Targeted Geoscience Initiative (TGI-5)
Released2019 03 01
AbstractRecent work on the largest sedimentary exhalative (SEDEX) district in Canada, the Howard's Pass district (HPD) in Selwyn Basin, Yukon, has shown that a persistently euxinic water column was not the source of sulphur in the mineralization, and that the redox conditions of the water column (and shallow subsurface) varied from anoxic to suboxic to euxinic. We have conducted a bulk geochemical and molybdenum isotopic traverse through a mineralized intersection in a single drill hole from the Anniv East vent-distal lead-zinc SEDEX deposit in the HPD. Bulk geochemical redox proxies generally show that redox conditions varied between (intermittently to permanently) suboxic, dysoxic, anoxic and euxinic. Herein we present new molybdenum isotope data for these same samples, and evaluate the efficacy of the application of this isotopic system to determining redox conditions of the water column and shallow subsurface, and examine the utility of molybdenum isotopes in providing genetic information for SEDEX deposits.
Molybdenum isotope values range from delta-98Mo -0.29 to 2.27 permille. There is good general agreement between the molybdenum isotope values and certain redox sensitive elements and established redox indicators for the unmineralized and mineralized host rocks; these relationships reflect suboxic or oxic conditions for the most negative values, and anoxic and euxinic conditions for the most positive values. This indicates that the application of molybdenum isotopes as a redox indicator in seafloor hydrothermal deposits in sedimentary (or volcano-sedimentary) settings shows great promise. Unlike thallium isotopes, molybdenum isotopes do not appear to be of use in fingerprinting SEDEX mineralization.
GEOSCAN ID313645