The Ellisras Basin is a geological basin that spans the border between South Africa and Botswana, extending west from the town of Lephalale (formerly Ellisras) in Limpopo province. Basin fill consists of sedimentary rocks of the Karoo Supergroup, with maximum thickness of 1,500 metres (4,900 ft).The principal economic resources in the basin are the Waterberg Coalfield in South African and the Mmamabula coalfields in Botswana.LocationThe Ellisras Basin is about north of the main Karoo Basin. It extends east from the Kalahari Basin that underlies much of Botswana. The South African portion of the Ellisras basin is about from east to west and from north to south. The portion in Botswana extends much further to the north and south.StructureThe basin formed at the same time as the Karoo Supergroup, and is around 310 to 180 million years old. It has the asymmetrical cross-section typical of a half-graben, bounded on the north side by a fault zone that slopes steeply down to the axis of the basin, while the southern side slopes down more gently. On the north it is bounded by the Melinda Fault Zone (MFZ), a zone of block faulting in the highly deformed and metamorphosed Archean-age rocks of the Limpopo Belt. The Eenzaamheid Fault Zone defines the southern boundary of the basin, where basin sediments abut older coarse-grained sandstones and minor mudstones in the Waterberg Group.
