Earth:Ganigobis Formation

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Short description: Late Carboniferous to Early Permian geological formation of the Dwyka Group in Southern Africa
Ganigobis Formation
Stratigraphic range: Gzhelian-Artinskian
302–297 Ma
TypeGeological formation
Unit ofDwyka Group
Sub-unitsGanigobis Shale Member
UnderliesEcca Group
OverliesNama Group
Thicknessup to 240 m (790 ft)
Lithology
PrimaryShale, conglomerate, sandstone
OtherTuff
Location
Coordinates [ ⚑ ] : 25°54′S 18°00′E / 25.9°S 18.0°E / -25.9; 18.0
Paleocoordinates [ ⚑ ] 56°00′S 35°54′W / 56.0°S 35.9°W / -56.0; -35.9
RegionǁKaras Region
Northern Cape
Country Namibia
 South Africa
ExtentAranos & Karoo Basins
Kalahari Craton
Type section
Named forGanigobis
LocationGanigobis, Fish River Canyon
Thickness at type section155 m (509 ft)
Damara-Orogen mit Damara-Gürtel, Kaoko-Gürtel und Gariep-Gürtel.png
Geologic map of Namibia with the Ganigobis Formation partly cropping out in the southern area (orange)

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 240 metres (790 ft) evidenced in the Vreda borehole.[1] The conglomerates, sandstones, shales and tuff of the formation were deposited in a glacio-lacustrine to marine environment.[2][3] 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),[4] sponges and sponge spicules, radiolaria, coprolites and permineralised wood.[5]

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.[5]

Fossil content

Among others, the following fossils are reported from the formation:[6][7][8]

Fish

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

  1. Bangert et al., 2000, p.266
  2. Ganigobis Formation at Fossilworks.org
  3. Bangert, 2000, p.21
  4. Bangert, 2000, p.60
  5. Jump up to: 5.0 5.1 Bangert, 2000, p.3
  6. Ganigobis at Fossilworks.org
  7. Wesselton Mine, Kimberley at Fossilworks.org
  8. Ganigobis, near Tses Station at Fossilworks.org

Bibliography

Further reading

  • B. G. Gardiner. 1962. Namaichthys schroederi Gürich and other Palaeozoic Fishes from South Africa. Palaeontology 5(1):9-21