The Kalahari Copperbelt in Central Namibia: Controls on Copper Mineralization

Abstract

ABSTRACT The Kalahari Copperbelt stretches discontinuously for 800 km from central Namibia to northern Botswana (Figure 1; Borg, 1988; Borg and Maiden, 1989). In central Namibia, copper mineralization, hosted by slate and phyllite, is intermittently developed over more than 60 km of strike of the Kagas Member of the Klein Aub Formation. The strata-bound nature of copper occurrences led early explorers to the conclusion that copper was either syngenetic, i.e., emplaced during deposition of the host strata, or diagenetic, i.e., emplaced into the host strata during burial and compaction. As a result, initial exploration largely focused on “favorable” stratigraphic units as target horizons and for the most part ignored structurally controlled target areas of significant economic potential. Subsequent research at the (presently inactive) Klein Aub Mine and elsewhere in the Namibian part of the belt showed that, although copper concentrations are broadly strata-bound, the structural associations (e.g., the relation to a late reverse fault at Klein Aub) and detailed textural features (e.g., copper in veins, brittle fractures, cleavage-parallel lenticles, and tectonic breccia zones) indicate that copper mineralization was emplaced into structurally controlled sites late in the deformation history of the region. The conclusion of the present review is that economically viable copper accumulations resulted predominantly from one or more regionally extensive but locally structurally controlled hydrothermal events, mostly subsequent to formation of the dominant cleavage. As a result, modern exploration should focus primarily on favorable structures, particularly potential dilatant sites in tectonically complex zones.