Geochemistry of contaminated komatiites from the Umburanas greenstone belt, Bahia State, Brazil

摘要

The late Archaean Umburanas greenstone belt (UGB) is located in the Sao Francisco Craton, southwest of Bahia State, Brazil. The lower unit of UGB comprises basal komatiite lavas and tholeiitic basalts intercalated with felsic volcanic rocks. The regional crystalline basement rocks, the Gaviao block, predominantly consist of granitic, granodioritic and migmatitic gneiss along with tonalite-trondhjemite-granodiorite (TTG) associations.