Abstract
With the need for steel ever increasing, the Kalahari Manganese Deposit is a resource of great
economic importance and as such, the need for accurate data and comprehensive studies on
the manganese and iron ores are vital. The Mukulu 265 project area is positioned along the
border of the high (Wessels-type) to low (Mamatwan-type) grade manganese ore and like the
neighbouring N’chwaning and Wessels mines, is subject to: intrusions by diabase dykes;
thrusting and subsequent overlapping of strata; normal faulting and associated Wessels event
enrichment; and erosion along two separate unconformities, namely the Mapedi/Gamagara
and the Kalahari unconformities. As a result of these structural evolutionary events, both the
iron and the manganese ores vary in grade, mineralogy and texture from north to south and
east to west. This variation is the result of contact metamorphism and associated igneousrelated
hydrothermal fluids; supergene alteration along the Mapedi/Gamagara unconformity;
and metasomatic alteration along the reactivated north-south striking normal faults. The latter
is responsible for the systematic residual enrichment in manganese content and the increase
in high-grade minerals in the manganese ore, as well as the subsequent leaching of carbonates
and silicates that is witnessed in the northern section of Mukulu 265. Based on varying
degrees of alteration from south to north on Mukulu 265, the banded iron formation, hematite
lutite and manganese ores have been broadly categorised into three classes, namely least
altered (LA), partially altered (PA) and highly altered (HA). The LA rock-types are
considered to be closest to the primary rock-types found on Mukulu 265 and show relatively
little alteration compared to the PA and HA samples. From the LA to the HA manganese ore
samples, there is a clear increase in manganese oxides such as hausmannite, predominantly at
the expense of carbonates such and kutnohorite and dolomite, particularly within the ovoids.
Sampling and analysing the manganese ore by visually distinguishing common subzones,
reveals a distinct pattern within the lower manganese ore beds of the selected boreholes that
shows a lateral geochemical trend. This geochemical trend exhibits higher concentrations in
manganese with lower concentrations in undesired elements such as iron within the lowercentral
portion of the lower manganese ore bed. The geochemical pattern exhibited by the ore
zones forms the basis by which the ore grade changes with depth and thus underpins its
importance for selective mining processes. An interpretation of the ore genesis based on
geochemical and mineralogical results for the lower manganese ore bed, suggests that the...
M.Sc. (Geology)