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TitreGeochemistry and metallogeny of Ag-Pb-Zn veins in the Purcell Basin, British Columbia
AuteurPaiement, J -P; Beaudoin, G; Paradis, S; Ullrich, T
SourceEconomic geology and the bulletin of the Society of Economic Geologists vol. 107, no. 6, 2012 p. 1303-1320, https://doi.org/10.2113/econgeo.107.6.1303
Année2012
Séries alt.Secteur des sciences de la Terre, Contribution externe 20090267
ÉditeurSociety of Economic Geologists
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.2113/econgeo.107.6.1303
Mediapapier; en ligne; numérique
Formatspdf
ProvinceColombie-Britannique
SNRC82F/01; 82F/02; 82F/07; 82F/08; 82F/09; 82F/10; 82F/15; 82F/16; 82G/03; 82G/04; 82G/05; 82G/06; 82G/11; 82G/12; 82G/13; 82G/14; 82J/03; 82J/04; 82J/05; 82J/12; 82K/01; 82K/02; 82K/07; 82K/08; 82K/09; 82K/10
Lat/Long OENS-117.0000 -115.0000 50.7500 49.0000
Sujetsgîtes minéralogiques; minéralisation; argent; plomb; zinc; gisements filoniens; roches sédimentaires; datation argon-argon; datations argon-argon; datation radiométrique; métallogénie; Bassin de Purcell ; Supergroupe de Purcell ; géochimie; géochronologie; géologie économique; Précambrien; Protérozoïque
Illustrationslocation maps; tables; photomicrographs; plots; photographs; histograms
ProgrammeCordillière du sud IGC-3, Initiative géoscientifique ciblée (IGC-3), 2005-2010
ProgrammeÉtude des gîtes de SEDEX, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
The Mesoproterozoic Purcell Basin in Canada contains three different types of veins: (1) type 1 Pb-Zn-Ag veins are composed of Fe-rich sphalerite, pyrrhotite, galena, freibergite, and pyrite with minor quartz gangue; (2) type 2 Pb-Ag-Cu-Au veins are characterized by galena, pyrite, freibergite, and gold in a quartz gangue; and (3) type 3 Ag-Pb-Zn vein and replacement deposits contain Fe-poor sphalerite, galena, pyrite, and freibergite in a quartz-dolomite gangue that locally replaces host dolostone. The sulfur isotope composition of type 1, 2, and 3 vein and replacement deposits closely reflects their respective stratigraphic positions. Type 1 and 2 veins hosted in lower Purcell sedimentary rocks have light sulfur isotope compositions (-4.8 to +2.5permil) similar to diagenic pyrite disseminated in clastic sedimentary host rocks. Type 3 veins and the replacement deposits hosted in upper Purcell Supergroup rocks have heavy sulfur isotope compositions (8.3 - 17.2permil) indicative of thermo-chemical reduction of marine sulfate in carbonate host rocks. Quartz from type 1 Pb-Zn-Ag veins has d18OSMOW values ranging from 7 to 17permil, whereas type 2 and 3 vein and replacement deposits have d18O values ranging from 9 to 20permil. The range of d18O values for type 1, 2, and 3 veins is the result of mixing of metamorphic fluids with a d18O value higher than 11.5permil and an upper crustal fluid with a d18O lower than 1.2permil, in equilibrium with the host rocks during Proterozoic (type 1) and Mesozoic-Cenozoic (type 2 and 3) hydrothermal events. Galena and freibergite lead isotope compositions plot in two groups, consistent with previous studies. Type 1 Pb-Zn-Ag veins have a nonradiogenic lead signature (206Pb/204Pb: 16.322 - 16.435) and are considered Proterozoic in age. Type 2 Pb-Ag-Au-Cu veins and type 3 Ag-Pb-Zn vein and replacement deposits have a radiogenic lead signature (206Pb/204Pb: 17.842 - 19.347) and are interpreted to be Mesozoic-Cenozoic in age. Hydrothermal sericite from the type 3 Ptarmigan replacement deposit yields a 40Ar/39Ar age of 133.1 ± 0.7 Ma, indicating a Cretaceous age for type 3 deposits. Type 1 veins are interpreted to be the result of hydrothermal fluids generated during the Proterozoic East Kootenay Orogeny, whereas type 2 and 3 veins and replacement deposits are interpreted to be the result of Late Cretaceous-Paleocene tectonism.
GEOSCAN ID248142