Syenite-associated disseminated gold deposits in the Abitibi greenstone belt, Canada


A distinct group of gold deposits in the Abitibi greenstone belt is spatially associated with quartz-monzonite to syenite stocks and dikes. The deposits occur mainly along major fault zones, in association with preserved slivers of alluvial–fluvial, Timiskaming-type, sedimentary rocks. The deposits consist of disseminated sulfide replacement zones with variably developed stockworks of quartz–carbonate±K-feldspar veinlets, within zones of carbonate, albite, K-feldspar, and sericite alteration. The syenitic intrusions are broadly contemporaneous with deposition of Timiskaming sedimentary rocks and, together with disseminated gold mineralization, they have been overprinted by subsequent regional folding and related penetrative cleavage. Disseminated gold orebodies occur within composite syenitic stocks or along their margins, along satellite dikes and sills, and along faults and lithologic contacts away from intrusions. Orebodies in these different positions are interpreted to represent proximal to distal components of large magmatic–hydrothermal systems centered on, and possibly genetically related to, composite syenitic stocks.