Abstract

The Mombezhi Dome, located in the northwestern province of Zambia 240 km west of the Copperbelt, contains several large low-grade stratiform copper occurrences of probable syngenetic origin in rocks of medium to high metamorphic grade.The copper is confined to a muscovitic schist unit, which contains both barren feldspar-biotite schists and mineralized muscovite-phlogopite-kyanite schists. This unit has been identified at numerous localities around the dome but is known to be well developed only at three localities. The mineralization consists of two mutually exclusive sulfide facies, namely, chalcopyrite-pyrrhotite-pyrite-cubanite and bornite-chalcopyrite-chalcocite.Deposition of the host rock and distribution of the sulfides are shown to be closely related to the paleotopography, the highest grade mineralization occurring in a series of sedimentary basins. Reconstruction of the original character of the deposits is difficult, due to intensive faulting and folding culminating in the probable overturning of the two principal deposits.It is believed that the copper was deposited simultaneously with the host sediments; metamorphism has, however, destroyed any primary structures within the mineralized schist. Age comparisons with other stratiform copper deposits in Zambia are difficult, but it is possible that the mineralization may be older than that of the Copperbelt.

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