Geochemistry of the Palaeoproterozoic gabbros and granodiorites of the Saza area in the Lupa Goldfield, southwestern Tanzania

The geochemical features of the gabbros are interpreted in terms of their derivation from the partial melting of an enriched mantle wedge in a continental arc setting whereas granodiorites are interpreted to have formed by magma-crust mixing processes. The resultant magmas of both rocks assimilated the pre-existing Archaean crust before their emplacement. The formation of the Lupa terrane in a continental arc coupled with the inferred subduction model in the Ubende terrane during the formation of MORB-like eclogites suggest that the subduction - thrust model cannot be ruled out in explaining the evolution of the Ubendian Belt.