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 language | English |
|---|---|
| Pages (from-to) | 430-451 |
| Number of pages | 22 |
| Journal | South African Journal of Geology |
| Volume | 98 |
| Issue number | 4 |
| Publication status | Published - 1995 |
ASJC Scopus subject areas
- Geology