Ph.D. project: Stable strontium (88 / 86Sr) isotope systematics in quartz-carbonate veins from orogenic gold deposits in the Val d´Or region, Quebec
Carbonate precipitation and decarbonation reactions are frequently associated with hydrothermal fluids and gold mineralization. The Val-D'Or vein field (Louvicourt to Malartic) in the Abitibi subprovince is a typical example of this association. The vein field and associated orogenic gold deposits in this zone are characterized by the association of gold with sulphide-quartz-carbonate veins (+/- tourmaline and other accessory minerals). The stable isotopes (C, O, H) and the radiogenic isotopes of strontium (87/86Sr) of the different phases in the veins (quartz, carbonate, tourmaline) indicate that gold was deposited due to mixing between hydrothermal (metamorphic) fluids and shallow crustal waters. The metamorphic fluids are the product of the dehydration and decarbonation reactions of the Archean crust. We propose an innovative use of the stable isotopes of strontium (88/86Sr) to constrain the role of carbonation and decarbonation reactions associated with the formation of veins and gold precipitation. The main objective of this study is to build better exploration models and to better understand the origin of gold in orogenic gold deposits.