Structural evolution and orogenic gold metallogeny of the western Wabigoon subprovince, Canada

Abstract

Some of the world’s largest orogenic gold deposits are hosted within granite-greenstone subprovinces of the Superior Province of Canada. The apparent gold endowment of the western Wabigoon subprovince is much less than that of the Abitibi subprovince, despite both Neoarchean subprovinces sharing similar structural and metallogenic histories. Further, the relationship between regional deformation and orogenic gold mineralizing events in the western Wabigoon subprovince is poorly constrained in comparison to other greenstone belts within the Superior Province. New structural mapping of the Dryden area of the western Wabigoon subprovince indicates that it experienced a N-S shortening event (D1), 2705-2695 Ma, which reactivated, or initiated the formation of, the E-W-trending Wabigoon and Mosher Bay-Washeibemaga deformation zones (Wdz and MBWdz, respectively). Following the D1 event, after 2695 Ma, a protracted period of NNW-SSE shortening (D2) localized transpression along the Manitou Dinorwic deformation zone (MDdz), which is spatially associated with orogenic gold systems, including the Goldlund deposit (~1.7 Moz Au) and Kenwest prospect (~0.3 Moz Au). During D2, the MDdz experienced sinistral transpression, while the Wdz and MDdz experienced dextral-sense movement. U-Pb geochronology of vein-hosted xenotime from the Goldlund deposit and Kenwest prospect indicate that hydrothermal events, and likely gold mineralization, occurred syn- to late- D2 deformation at 2664 ± 8.3 Ma and 2580 ± 12 Ma, respectively. The structural evolution and orogenic metallogeny of the western Wabigoon subprovince is similar to that of anomalously gold- rich subprovinces of the Superior Province. Therefore, it is proposed that the structural evolution of individual greenstone belts is not the primary controlling factor on their bulk gold endowment. Nevertheless, orogenic gold deposits are spatially associated with major deformation zones and linked to widespread hydrothermal event(s), spanning 2680-2580 Ma across the southern Superior Province.