Geology of the Cambrian Marinkas Quellen carbonatite–alkaline complex (Southwest Namibia)

We present a new geological map of the Marinkas Quellen carbonatite-alkaline complex (Southwest Namibia), which forms part of the Cambrian Kuboos-Bremen Igneous Province. Our mapping reveals that the complex was assembled through several pulses of alkaline silicate and conjugate carbonatitic melts, which formed by liquid immiscibility from strongly alkaline, mantle-derived parental melts. Alkaline melts crystallized ijolites and syenites, while carbonatitic melts evolved by fractional crystallization from calcite-carbonatites, through dolomite-carbonatites, to ferro-carbonatites. The final emplacement was controlled by late-magmatic, fluid-mediated processes, which induced the recrystallization of part of the carbonatites, andredistributed alkali and light Rare Earth Elements (REE) through and around the intrusive complex. Fluid release and consequent over-pressurization during magma uprise enhanced hydraulic fracturing and brecciation in the country rock and within the complex itself, promoting further magma ascent. The Marinkas Quellen carbonatite-alkaline complex is an outstanding case study to investigate the physico-chemical processes of carbonatites genesis, evolution and emplacement.