Abstract
KMR mine is owned by Kudumane Manganese Resources. It is located on the farm York 279 some 60 km northeast of Kuruman along the eastern margin of the Kalahari Manganese Field (KMF) of the Northern Cape Province, South Africa. Extraction of Mn ore is currently focused in the lower (Mn bed) of three Mn beds all of which are interbedded with iron formations. The three Mn beds occur within the Hotazel Formation of the early Paleoproterozoic Voëlwater Subgroup of the Transvaal Supergroup in the Griqualand West region. This study focused on the upper Mn bed at KMR Mine, which has not been investigated in detail previously because it was deemed to be too thin and uneconomic in some parts of the KMF. Based on macroscopic to mesoscopic features observed during core logging, the upper Mn bed is subdivided into nine lithostratigraphic zones which are further grouped into four facies based on the presence, size and distribution of diagenetic features such as fine laminae, lenticles and ovoids. Facies 1 describes zones such as zones A, C and H which display more ovoids (up to 5mm in size) than lenticles and mesobands. Facies 2 comprises only zone F which displays ovoids (up to 2mm in size)only. Facies 3 consists of zones B, D and G, which appear more lenticular in texture with smaller sized ovoids (up to 1mm in size). Facies 4 comprises zones E and I which show no visible diagenetic textural features and are seemingly massive in appearance. Optical and scanning electron microscopy done on thin sections of representative samples revealed that the upper Mn bed is similar to Mamatwan-type ore (Kleyenstüber, 1984,1985) and has a microcrystalline texture that shows little to no signs of recrystallization. The two most common textures encountered in the upper Mn bed during this study were: (1) prominent, coarse-grained ovoids; and (2) sparry carbonate lenticles. A carbonate mineral such as kutnohorite, which commonly makes up the mineral composition of diagenetic features such as ovoids, is replaced by an oxide such as hausmannite, resulting in concentric-shaped ovoid-like structures. A barite-hausmannite mineral assemblage is also noted to be common in the partially replaced carbonate ovoids. Geochemical data acquired using whole rock X-ray fluorescence (XRF) and solution inductively coupled plasma mass spectrometry (ICP-MS) show the most apparent negative correlation between CaO and Mn3O4 in the majority of lithostratigraphic zones in drill core samples investigated. This trend is attributed to the leaching of Ca. An inverse correlation exists between Fe2O3 and Mn3O4. Zones in some drill cores are ferruginized, containing high Fe2O3 and simultaneously decreased Mn3O4. Samples with high Mn3O4 tend to show increased Cu and Zn with decreased Fe2O3 contents. Mn3O4 is inversely correlated with both MgO and SiO2 in many analyzed samples...
M.Sc. (Geology)