Abstract

A stratabound and stratiform lead-zinc sulfide deposit, confined to the rocks of the upper volcanoclastic portion of the Precambrian Kapok Formation, was discovered in 1963 in the south of South West Africa.The ore horizon consists of a well-bedded sedimentary sequence comprising presumably biologically and chemically precipitated sediments, namely microquartzite (a carbonaceous "chert"), carbonates, sugary quartz, and massive sulfides with intercalated detrital quartzite and argillite. Carbon- and barium-bearing minerals are ubiquitous in all the rocks of the ore horizon as well as in the footwall and hanging wall. The latter, which is not mineralized, is composed of arkosic quartzite and grits and has a fairly sharp contact with the ore horizon. The footwall, consisting of an arkosic quartzite, is featured by brecciation and disseminated sulfides and stringer ore in interfragmental dolomite veins. The brecciation and mineralization of the footwall rocks probably took place contemporaneously with the deposition of the orebody and is not considered to be genetically related to later deformation. Silicification of the footwall is in evidence. The sediments are all characterized by sedimentary slumping, facies changes over short distances, and even local unconformities.All the presently known orebodies are characterized by intricate structures which can be ascribed to at least two periods of tectonic deformation, i.e., folding and refolding.It is proposed that the ore is genetically related to volcanogenic massive sulfide deposits.

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