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TitreRecent advances in fluid and melt inclusion and applied mineralogical research in the Sudbury mining camp: improving ore genesis models and exploration success
TéléchargerTéléchargement (publication entière)
AuteurHanley, J J; MacMillan, M A; Kerr, M J; Watts, K M; Warren, M R; Ames, D E
SourceTargeted Geoscience Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models; par Ames, D E (éd.); Houlé, M G (éd.); Commission géologique du Canada, Dossier public 7856, 2015 p. 209-231, (Accès ouvert)
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
Référence reliéeCette publication est contenue dans Ames, D E; Houlé, M G; (2015). Targeted Geoscience Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models, Commission géologique du Canada, Dossier public 7856
Lat/Long OENS -82.0000 -80.0000 47.0000 46.0000
Sujetsméthodes analytiques; nickel; platine; établissement de modèles; genèse des minerais; métallogénie; chrome; cuivre; études des isotopes stables; inclusions fluides; minéralisation; apatite; biotite; Ceinture de Bird River Greenstone ; Ceinture d'Abitibi Greenstone ; Province de Nain ; Province de Superior ; Complexe de Sudbury Igneous ; géochimie; pétrologie ignée et métamorphique
ProgrammeÉtude des gîtes magmatiques de Ni-Cu-EPG, Initiative géoscientifique ciblée (IGC-4)
Diffusé2015 06 22
Résumé(disponible en anglais seulement)
A variety of microanalytical techniques (LA-ICP-MS, microthermometry, SIMS) were applied to resolve uncertainties about the chemical evolution of the Sudbury Igneous Complex (SIC) melt sheet and its associated hydrothermal systems. In the SIC sublayer and main mass, silicate melt inclusions in early apatite cumulate grains preserve evidence for high-temperature (>1100°C) immiscibility between Fe-rich and Sirich liquids. Melt inclusions record the base metal (Ni, Cu, Co) endowment of the melt sheet prior to and after sulphide saturation and allow quantification of trace element partitioning at various stages during meltsheet evolution, and prediction of the likelihood that an offset dyke contains or does not contain sulphide ore deposits locally. Melt inclusions were deemed unaffected by post-cumulus processes, providing an opportunity to characterize primary magmatic processes otherwise obscured by 1.85 Ga of metamorphism, deformation, and hydrothermal alteration. In the sublayer, analysis of the trace element chemistry of alteration, metamorphic and igneous biotite identified the chemical signature of biotites associated with the host inclusion-rich quartz diorite offset-style Ni-Cu-platinum-group element (PGE) sulphide orebodies, characterized by elevated Ni, Cu, and Ni/Cr ratios. Trace metal analysis of biotite allows differentiation between this key rock type and barren quartz diorite that is otherwise compositionally and textually comparable. In footwall Cu-Ni-PGE ore deposits, alteration, fluid inclusion, and stable isotope studies provide a systematic description of "low-sulphide" deposit style. Hydrothermal sulphide precipitation, a process recorded in alteration vein styles, was associated with mixing of oxidized, 18O-enriched, high salinity metal-rich fluids with cooler, reduced, 18O-depleted, high-Ca groundwaters. Recognition of this mixing process through isotope mapping, fluid inclusion microthermometry, and alteration mineral chemistry provides a means to identify metal-precipitation fronts within the complex footwall environment.