The Ganigobis Formation is a Late Carboniferous (Gzhelian) to Early Permian (Artinskian) geologic formation of the Dwyka Group in the ǁKaras Region of southeastern Namibia and the Northern Cape of South Africa. The widespread formation was deposited in the Aranos and Karoo Basins of southern Africa.
Description
The Ganigobis Formation is an extensive unit with a maximum thickness of evidenced in the Vreda borehole. The conglomerates, sandstones, shales and tuff of the formation were deposited in a glacio-lacustrine to marine environment. The Ganigobis Formation provides fossil fish as well as bivalves (e.g. Nuculopsis), gastropods (e.g. Peruvispira), scyphozoa (e.g. Conularia), crinoid stalks, foraminifera (Hyperammina, Ammodiscus, Glomospira, Ammobacculites and Spiroplectammina), sponges and sponge spicules, radiolaria, coprolites and permineralised wood.
Zircons of the Ganigobis Shale Member yield SHRIMP-ages of 302-300 Ma. This dates the uppermost part of the second deglaciation sequence in southern Namibia to the Late Carboniferous (Gzelian) and provides a minimum age for the onset of Karoo-equivalent marine deposition. The age of the uppermost argillaceous part of the third deglaciation sequence (297 Ma) was determined from zircons of a tuffaceous bed sampled in a roadcut in the Western Cape Province, South Africa.
Fossil content
Among others, the following fossils are reported from the formation:
Fish
Acrolepis addamsi
Namaichthys schroederi
Watsonichthys lotzi
See also
List of fossiliferous stratigraphic units in Namibia
List of fossiliferous stratigraphic units in South Africa
Geology of Namibia
Geology of South Africa
Irati Formation
References
Bibliography
Further reading
B. G. Gardiner. 1962. Namaichthys schroederi Gürich and other Palaeozoic Fishes from South Africa. Palaeontology 5(1):9-21