Facies of the Merensky Reef

Mention reef facies to most geologists and they might conjure up a mental image of a carbonate reef complex. But to geologists working in the Bushveld Complex, reef facies is a descriptive term used to account for the variation a single mineralized horizon exhibits within the layered ultramafic-mafic sequence. One such horizon is that of the Merensky Reef, which has been laterally subdivided into different facies based on modal characteristics and textural appearance of the reef itself. The inherent complexities of these reef facies are revealed by detailed logging of numerous diamond drill cores through stratigraphic intervals. Continue reading

Steenkampskraal Thorium Mine

What follows is a description of the early mining history of the Mesoproterozoic-age Steenkampskraal monazite ore body located in southern Namaqualand, about 340 km north of Cape Town in South Africa. Steenkampskraal is a massive-lode ore body, possibly originating by igneous processes from an immiscible phosphate-sulphide-oxide magmatic liquid. The monazite ore occurs in a thin lenticular-shaped body surrounded by Mesoproterozoic granitic gneiss country rocks. The ore body is about 400 m in strike-length, extending about 450 m down-dip, with an average thickness of about 0.5 m. Continue reading