The Neoproterozoic rocks of the Zambian Copperbelt host world-class sediment-hosted stratiform and stratabound Cu-Co deposits in both fine- and coarse-grained metamorphosed siliciclastic rocks. Ore deposits in the coarse-grained siliciclastics occur below (footwall deposits) and above (hanging-wall deposits) the fine-grained Ore Shale Formation and are termed arenite-hosted deposits. The arenite-hosted deposit at Mufulira is studied and compared with similar deposits in the Central African Copperbelt to propose an integrated ore-forming model. The arenites are characterized by several alteration, dissolution, and cementation phases. Authigenic phases include quartz, albite, and K-feldspar overgrowths and calcite and dolomite cements filling pores. Carbonaceous matter or pyrobitumen postdates compaction and coat detrital grains. The pyrobitumen formed as a residue of oil cracking and/or as a byproduct of sulfate reduction and the oxidation of hydrocarbons. Chalcopyrite, digenite, chalcocite, covellite, carrolite, pyrrhotite, malachite, and iron oxides occur as finely disseminated ores or as replacive blebs in sericitic quartzites. The ore minerals replace the compacted rock, and may enclose all diagenetic phases and occur together with quartz and calcite in veins, indicating they formed late in the paragenesis. Ore minerals precipitated as the result of the mixing of a highly saline, metal-bearing brine with an H2S-rich hydrocarbon reservoir.
