Major and trace element and isotopic (Sr, Nd, O) constraints for Pan-African crustally contaminated grey granite gneisses from the southern Kaoko belt, Namibia

The final stages of continental collision during westward dipping subduction of the Kaoko belt beneath the Ribeira belt took place between ca. 590 and 520 Ma. In view of such a Pan-African subduction zone related geotectonic situation, the Nk granite gneisses are products of melting events in arc-derived rocks, produced in an earlier stage of the Pan-African orogeny.