Reactive transport modelling of ore mineral zoning and the paragenesis of copper sulfides in sediment-hosted stratiform ore deposits, the Katanga Copperbelt (DRC)

Abstract

Reactive transport modelling was carried out to simulate the transport and precipitation conditions of copper sulfide minerals in the sediment-hosted ore deposits of the Central African Copperbelt. The results illustrate the advancement of a mineral front due to the reaction of copper-rich fluids with host rocks. Chalcopyrite (CuFeS2) initially precipitates in the reducing host rock and pyrite (FeS2) dissolves, but the latter re-precipitates as a halo beyond the chalcopyrite. Continuous supply of copper causes the formation of the copper-rich sulfide bornite (Cu5FeS4) followed by chalcocite (Cu2S) with precipitation of chalcopyrite and pyrite further down the flow direction. Anhydrite disappears where both copper sulfides and pyrite are precipitated. The modelled sulfide paragenesis and the general distribution of these minerals correspond to patterns observed in rocks within the Katanga Copperbelt.