Fault-controlled hydrothermal alteration of Palaeoproterozoic manganese ore in Wessels Mine, Kalahari manganese field

N. J. Beukes, A. M. Burger, J. Gutzmer

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)

Abstract

The Kalahari manganese field is the largest known land-based manganese deposit. Low-grade sedimentary Mamatwan-type ore dominates and constitutes about 97% of the ore reserves. High-grade Wessels-type ore constitutes about 3% of the known reserves in the NW of the area. Here the sequence is displaced by a system of north-south-striking normal faults. Fault zones are ferruginized and alongside faults sedimentary Mamatwan-type ore has been upgraded by hydrothermal alteration to Wessels-type ore. Hydrothermal alteration of Mamatwan-type ore to Wessels-type ore involved leaching of SiO2 and oxidation of manganese-bearing carbonates to manganese oxides. Normal faults apparently acted as conduits for hydrothermal fluids. Hydrothermal alteration appears to have taken place in a type of convection cell with SiO2 and CO2 leached from Mamatwan-type ore, reprecipitated in proximity to the normal faults as secondary braunite and calcite. -from Authors

Original languageEnglish
Pages (from-to)430-451
Number of pages22
JournalSouth African Journal of Geology
Volume98
Issue number4
Publication statusPublished - 1995

ASJC Scopus subject areas

  • Geology

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