Tswane Formation

Tswane Fm

Period:

Permian

Age Interval:

Early Permian (Sakmarian)

Province:
SouthAfrica-Namibia-Botswana

Type Locality and Naming

Kalahari Basin (NE). Named and formally defined primarily from extensive borehole cores in the northern Kalahari Basin by the Botswana Geological Survey. Lower formation in Ecca Gr in Kalahari Basin (NE).

Synonym:

Lithology and Thickness

Predominantly a fine-grained argillaceous succession. It comprises a basinal sequence of dark grey to black carbonaceous mudstones, often interlaminated with lighter grey siltstones.

Lithology Pattern:

Claystone

Relationships and Distribution

Lower contact

Conformably overlies the glaciogenic deposits of the Dukwi Fm (Dwyka Gr equivalent). Where the Dukwi was not deposited due to elevated paleo-topography, it can rest directly and unconformably on the Precambrian basement.

Upper contact

Conformably overlain by the coarse-grained, feldspathic fluvio-deltaic sandstones of the Mea Fm (Mea Arkose).

Regional extent

Widespread across the subsurface of the northern and northeastern sub-basins of the Kalahari Basin in Botswana (such as the NE Kalahari-Karoo Basin). Lower Ecca Gr equivalent. It chronostratigraphically correlates with the Bori Formation (Central/Southern Botswana) and the Makoro Formation, as well as the Prince Albert and Pietermaritzburg formations in the Main Karoo Basin of South Africa.

GeoJSON

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Fossils

Age

Early Permian (Sakmarian)

Age Span:

Beginning stage:

Sakmarian

Fraction up in beginning stage:

0.5

Beginning date (Ma):

292.02

Ending stage:

Sakmarian

Fraction up in the ending stage:

1.0

Ending date (Ma):

290.51

Depositional setting

Post-glacial deep-water lacustrine to pro-delta environments.

Depositional pattern:

Additional Information

Compiler:

From the O. Catuneanu et al. / Journal of African Earth Sciences 43 (2005) 211–253; Smith, R. A. (1984): The lithostratigraphy of the Karoo Supergroup in Botswana. Geological Survey of Botswana.