Origin of the Nchanga copper-cobalt deposits of the Zambian Copperbelt

The Cu-Co deposits of the Nchanga Mine in the Zambian Copperbelt are consistently hosted by arenites or arkoses with mineralization progressing for short distances into overlying shales. The ore horizons show a consistent association with flat-lying structures and in the Upper Orebody, are developed within thrust controlled antiformal structures. Hydrothermal alteration includes phlogopite +/- sericite followed by dolomite precipitation. and available stable delta S-34 of sulfides and delta C-13 data for carbonates are consistent with "in situ" thermochemical reduction of a sulphate rich fluid. The new data reported here suggest a strong link between Cu and Co ore formation in the Zambian Copperbelt and the development of structures during basin inversion and the onset of the Lufilian orogeny.