Kwetla Fm
Type Locality and Naming
Central and southern Botswana. Because it is almost entirely concealed beneath the Cenozoic sands of the Kalahari Desert, it was formally defined from deep stratigraphic and groundwater boreholes by the Botswana Geological Survey. Included in Beaufort Gr in Kalahari Basin (Central).
Synonym:
Lithology and Thickness
Dominated by a thick succession of non-carbonaceous argillites. It consists primarily of pale green, yellow, grey, and occasionally purple massive to laminated mudstones and siltstones. The base often features micaceous siltstones. It strongly contrasts with the underlying Ecca units due to the general absence of significant carbonaceous material or thick coals.
Relationships and Distribution
Lower contact
Conformably or transitionally overlies the coarse, coal-bearing deltaic sandstones of the Boritse Fm or Kweneng Fm (upper Ecca Gr equivalents).
Upper contact
Unconformably overlain by the Mosolotsane Fm (Stormberg Gr equivalent).
Regional extent
Widespread in the subsurface of the central and southern Kalahari Basin in Botswana (e.g., Okwa area, southern Botswana). Beaufort Gr equivalent. It is the regional chronostratigraphic equivalent of the Tlhabala Fm (eastern Botswana) and the Kule Fm (southwestern Botswana / Gemsbok Sub-basin), correlating with the lower Beaufort Gr (Adelaide Subgroup) in the Main Karoo Basin of South Africa.
GeoJSON
Fossils
Age
Depositional setting
Shallow lacustrine and expansive, low-energy terrestrial floodplain environments.
Additional Information