Enriched mantle one (EMI) type carbonatitic volcanism in Namibia: Evidence for a concentrically-zoned Etendeka plume head

•The Okorusu complex in NE Etendeka have Gough-type isotopic composition.•Messum igneous complex in SW Etendeka show a Doros/Tafelkop-type composition.•Both Gough- and Doros-type components derived from the Tristan-Gough plume.•Doros-type volcanism is surrounded by Gough-type volcanism.•The head-stage of Tristan-Gough plume coincide with the concentric zonation model.