Origin of hydrothermal mineral deposits

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The long-term goal of my research program is to understand the sources, flow paths, chemical and isotopic exchange, and mixing histories of hydrothermal fluids circulating in the crust and that form hydrothermal deposits. In this Discovery Grant proposal, emphasis will be to characterise fluids and their pathways from metamorphic sources that form hydrothermal orogenic gold mineralization. These data enable reconstruction of the crustal hydrogeology of ancient hydrothermal systems to understand how these fluids formed important mineral resources. Parameters that control crustal-scale hydrothermal fluid flow are studied using sophisticated 3D numerical models that simulate transport and exchange between hydrothermal fluids and a rock matrix cut by discrete fractures. For the next five years of my long-term research program, I propose to carry an integrated study of orogenic gold mineralization from fluid flow paths, to sources, to localized precipitation of gold, comprised of three specific projects: 1) the crustal hydrogeology, at the scale of a large orogenic gold deposit (Sigma, Abitibi) to understand deposit-scale fluid flow patterns in relation to the district-scale fluid flow patterns; 2) the in situ stable isotope composition of coexisting quartz (O) and tourmaline (H, B, O, Sr) from orogenic gold veins to resolve the compositional variation of fluid composition during formation of orogenic gold deposits; 3) the fluid inclusion PTX properties and sulphide chemical and isotope composition in relation to gold grade at the Lac Herbin mine to provide constraints for gold deposition mechanisms.