The geology of the coal-bearing rocks of the Karoo Sequence in the Tshikondeni Mine area, northern Transvaal

Abstract

This study describes the general geology of the Tshikondeni Mine area, and suggests a reconstruction of the depositional palaeoenvironment of the different sedimentary units. The palaeoenvironmental model is further related to the quality of the main coal seams. The sedimentary palaeoenvironment was established by identifying and describing seven vertically stacked genetic units of sedimentation, comprising twelve different lithofacies. These are related to sedimentary processes, from which a palaeoenvironmental model is derived. The sedimentation at Tshikondeni commenced with glacial, glaciofluvial and glaciolacustrine deposition. This was followed by deltaic, fluvial and lacustrine settings with associated coal seams. Coal distribution, petrography and quality parameters (ash, volatile matter) appear to be closely related to inferred palaeoenvironmental characteristics. Structurally, the area is complex and numerous faults occur. The faulting is due to extensional tectonism. Intrusive basaltic dykes and sills are numerous and further complicate exploitation of the economic coal seams.