3.63 Ga grey gneisses reveal the Eoarchaean history of the Zimbabwe craton

Abstract

Grey gneisses from the Tokwe and Rhodesdale terrains of the Zimbabwe craton have zircon ages of ~3.63, 3.52, and 3.34 Ga, validating the existence of Eo- to Palaeoarchaean crust. In-situ zircon Hf isotope compositions reveal the interplay between episodes of juvenile magma addition, crustal thickening and crustal differentiation. Starting from juvenile mafic crust (with chondritic composition) at ~3.9 Ga, the oldest nucleus of the Zimbabwe craton developed into a stable crustal block by ~3.35 Ga, following a tectonic and mantle evolution that is mirrored by other ancient terrains.