A provisional basinal study of the Waterberg-Karoo, South Africa

Abstract

The formation of the Ellisras basin was influenced by the repeated tectonic instability that is also be noted through the changes in the energy levels of the depositing media of the basin-fill, from the early Carboniferous period, as already indicated by Siepker (1986). This theory is also supported by MacRae (1988) who suggests that the sediment accumulation in certain sections of the Ellisras Basin was indicative of periods of palaeoslope rejuvenation resulting in sandstones, grits and minor conglomerates, alternating with periods of stasis when extensive coal seam deposition occurred. Studies completed in this thesis indicate the influence of basin movement and depositional thickness of the basin’s formations. These depositional patterns are closely related to mobile geological structures such as lineaments or faults of continuously active geological structures. Bumby and van der Merwe (2004) and Bordy (2000) indicate the possible influence of the Limpopo Mobile Belt as well as the failed East African Rift System on the formation of neighbouring basins. Geological structures also present in the Ellisras Basin can also be observed in these neighbouring bodies such as the Tuli, Tshipise and the Soutpansberg basins. Observations within the region of the Ellisras Basin, made in neighbouring Botswana by Arnott and Williams (2007) describe the Soutpansberg trough as the main influence in the formation of the Ellisras, Mmamabula and Mopane coalfields. These observations are in line with the findings of this thesis which indicates the consistent presence of continuously active geological structures within this region such as the greater intracratonic Soutpansberg trough which indicated re-activation during late Permian to early Triassic times. Copyright