Lisbon Formation

Lisbon Fm

Period:

Triassic, Jurassic

Age Interval:

Late Triassic-Early Jurassic (Norian-Sinemurian)

Province:
SouthAfrica-Namibia-Botswana

Type Locality and Naming

Ellisras Basin. Named after the farm Lisbon in the Ellisras (now Lephalale) district of the Limpopo Province. It is a formally recognized lithostratigraphic unit of the Karoo Supergroup specifically within the isolated, fault-bounded Ellisras Basin. Middle formation in Stormberg Gr

Synonym:

Lithology and Thickness

A relatively uniform, fine-grained "red bed" succession with a remarkably constant thickness of about 100 to 110 meters throughout the basin. It comprises a succession dominated by massive, red to maroon mudstones with subordinate intercalations of siltstone.

Lithology Pattern:

Siltstone

Relationships and Distribution

Lower contact

Rests with a sharp to gradational contact upon the coarser-grained fluvial sandstones of the Greenwich Fm (the local equivalent of the Molteno Fm).

Upper contact

Conformably and transitionally overlain by the massive, fine-grained aeolian desert sands of the Clarens Fm

Regional extent

Restricted entirely to the subsurface and rare sub-outcrops of the Ellisras Basin (Waterberg Coalfield) in northwestern South Africa, near the Botswana border. Because the basin is largely covered by recent sands and soils, this formation is known primarily from extensive coal exploration drilling. Stormberg Gr (Middle unit in the Ellisras Basin). It is the direct regional chronostratigraphic equivalent of the Elliot Fm in the Main Karoo Basin and the Irrigasie Fm (upper portion) in the Springbok Flats Basin.

GeoJSON

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Fossils

Age

Late Triassic-Early Jurassic (Norian-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, highly oxidized floodplain environments.

Depositional pattern:

Additional Information

Compiler:

From the O. Catuneanu et al. / Journal of African Earth Sciences 43 (2005) 211–253; SACS / Johnson, M.R., et al. (2006): Sedimentary rocks of the Karoo Supergroup. In: The Geology of South Africa; MacRae, C.S. (1988): Palynostratigraphic correlation between the Lower Karoo Sequence of the Waterberg and Pafuri coal-bearing basins and the Hammanskraal plant macrofossil locality; Fourie, C.J.S., et al. (2009): Interpretation of the Waterberg Coalfield Airborne Geophysical Data. Coaltech Final Report.