Ni-Cu-PGE Metallogenesis of Komatiitic Rocks in the Abitibi Greenstone Belt, Canada

Abstract

All komatiitic rocks in the 2.7 Ga Abitibi greenstone belt, Canada contain similar PGE abundances, regardless of age, depth of melting, and/or residue composition. Furthermore, all komatiitic rocks in the Abitibi greenstone belt appear to have been initially sulfide undersaturated and show only local evidence of sulfide segregation, consistent with sulfide saturation during lava emplacement and/or crystallization. Ni-Cu-(PGE) mineralization in the Abitibi greenstone belt has been found only in the two oldest assemblages, the Kidd-Munro and Tisdale assemblages. Only these assemblages contain lava channels or channelized sheet flows and sulfide-bearing sediments. Thus, physical volcanology is more important than magma composition in determining the prospectivity of komatiitic rocks in the Abitibi greenstone belt and elsewhere.