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Mosolotsane Formation

Mosolotsane Fm


Period: 
Triassic, Jurassic

Age Interval: 
Late Triassic-Early Jurassic (Norian to Sinemurian)


Province: 
SouthAfrica-Namibia-Botswana

Type Locality and Naming

Kalahari Basin (Central), Kalahari Basin (NE). Named after the Mosolotsane area in Botswana. Like most Karoo units in Botswana, it was formally mapped and defined from extensive borehole core logging by the Botswana Geological Survey, alongside scattered surface outcrops. Lower formation in Stormberg Gr in Kalahari Basin (Central)

Synonym:


Lithology and Thickness

A classic terrestrial "red bed" sequence. It is composed predominantly of reddish, purplish, and maroon mudstones and siltstones, interspersed with subordinate lenses of fine- to medium-grained fluvial sandstones.


Lithology Pattern: 
Siltstone


Relationships and Distribution

Lower contact

Rests unconformably on the argillaceous (muddy) Beaufort Gr equivalents (such as the Tlhabala Fm in central Botswana or the Kwetla Fm).

Upper contact

Conformably to paraconformably overlain by the massive aeolian desert sandstones of the Ntane Fm (the Clarens Fm equivalent).

Regional extent

Widespread across the central, eastern, and northern sub-basins of the Kalahari Basin in Botswana, typically underlying the prominent Ntane Sandstone Aquifer. Lower to Middle Stormberg Gr equivalent. It is the direct regional chronostratigraphic equivalent of the Elliot Fm in the Main Karoo Basin (South Africa) and the Dondong Fm in the southwestern Kalahari Basin (Botswana).


GeoJSON

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Fossils


Age 

Late Triassic-Early Jurassic (Norian to Sinemurian)

Age Span: 

    Beginning stage: 
Norian

    Fraction up in beginning stage: 
0.6

    Beginning date (Ma): 
214.36

    Ending stage: 
Sinemurian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
192.90

Depositional setting

Continental, semi-arid fluvial and floodplain environments.


Depositional pattern:  


Additional Information

The Mosolotsane Formation is a crucial marker for tracking the progressive climatic aridification of southern Africa during the Late Triassic and Early Jurassic prior to continental breakup.


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; Johnson, M.R., et al. (1996): Stratigraphy of the Karoo Supergroup in southern Africa: an overview.