Katangan Basin evolution and architecture: controls on ore location in the world's premier sedimentary copper province

The Central African Copperbelt, spanning the Zambian-Congolese border, is the world’s largest sedimentary copper province. Ores are hosted largely in evaporitic strata of the Neoproterozoic Katangan Basin, a product of Rodinia dispersal, and latest Neoproterozoic to Ordovician (Pan African) orogenesis. Existing structural models for the evolution of the Katangan Basin invoke high magnitude thrust transport and associated dismemberment of the middle and upper Katangan Supergroup stratigraphy, and ores hosted therein. We test these models and present new data that place important constraints on the pre-orogenic configuration of the basin, and the controls on ore location. Our results indicate that macroscale extensional basin architecture remained relatively little modified by orogenesis, with classical stratiform copper ores positioned about the condensed fringe of a central depocentre maximum. The complex structural geometries that characterize the Congolese arm of the copperbelt, in particular, were largely inherited from a systematically orientated array of extension-related halokinetic structures: diapirs, salt walls, salt allochthons, and withdrawal sub-basins. The arrangement of these intra- and supra-salt structural elements were in turn inherited from a syn-rift structural architecture developed at the initiation of basin growth. The position of classical “Mines Subgroup”-hosted ores appears strongly influenced both by the geometry of the syn-rift compartment, and the localization of overlying salt welds, the latter providing cross-stratal permeability that directed deep-seated fluids to intra-salt redox interfaces. High exploration potential is considered to exist for “non-classical” stratiform ores positioned at various stratigraphic levels beyond the original limits of salt.