Escarpment Grit Explained

Escarpment Grit
Type:	Geological formation
Period:	Early Triassic
Age:	Early Triassic
Prilithology:	Gritstone
Otherlithology:	Sandstone
Namedfor:	Descriptive name
Namedby:	A.M. MacGregor, Zimbabwe Geological Survey
Country:
Unitof:	Upper Karoo Group, Karoo Supergroup
Underlies:	Pebbly Arkose Formation
Overlies:	Lower Karoo Group

The Escarpment Grit is a Triassic geologic formation.^[1] It is also referred to as the Nyoka Grit.^[2]

Geology

The formation is composed of fluvial sediments, mainly gritstones and coarse sandstones.^[3] Uranium is present in the Escarpment Grit of southern Zambia.^[4]

Stratigraphy

The Escarpment Grit Formation is the basal unit of the Upper Karoo Group^[5] and underlies the Pebbly Arkose Formation.^[6] It has been dated as Upper Scythian (Early Triassic).

The Pebbly Arkose has been correlated to the Angwa Sandstone Formation in the Mana Pools and Cabora Bassa Basins,^[7] and the Elliot Formation of the Great Karoo Basin, South Africa.^{[6] [8]}

Flora

Alisporites spores have been identified from the Escarpment Grit in north-western Zimbabwe.^[7]

Hydrogeology

This formation constitutes a productive aquifer in north-western Zimbabwe, although of limited thickness.^[9]

Notes and References

1. 10.1016/S0899-5362(99)00014-7. Tectonic and climatic controls on sedimentation during deposition of the Sinakumbe group and Karoo supergroup, in the mid-Zambezi Valley Basin, southern Zambia. 1999. Nyambe. Imasiku A.. Journal of African Earth Sciences. 28. 2. 443–463. 1999JAfES..28..443N .
2. 10.1016/0899-5362(90)90052-G. Depositional evolution of permo-triassic karoo basins in Tanzania with reference to their economic potential. 1990. Kreuser. T. Wopfner. H. Kaaya. C. Markwort. S. Semkiwa. P. Aslandis. P. Journal of African Earth Sciences. 10. 1–2. 151–167. 1990JAfES..10..151K .
3. 10.1016/S0899-5362(00)00037-3. Sedimentology of the Madumabisa Mudstone Formation (Late Permian), Lower Karoo Group, mid-Zambezi Valley Basin, southern Zambia. 2000. Nyambe. Imasiku A.. Dixon. Owen. Journal of African Earth Sciences. 30. 3. 535. 2000JAfES..30..535N .
4. 10.1016/0899-5362(92)90104-K. A uranium orientation survey in Sikaneka area, Southern Zambia. 1992. Sikatali. C. Njamu. M. Journal of African Earth Sciences. 14. 2. 275. 1992JAfES..14..275S .
5. 10.1016/S0899-5362(01)00090-2. Sedimentology of the upper Karoo fluvial strata in the Tuli Basin, South Africa. 2001. Bordy. Emese M.. Catuneanu. Octavian. Journal of African Earth Sciences. 33. 3–4. 605. 2001JAfES..33..605B .
6. 10.1016/S0899-5362(97)00081-X. Stratigraphy and palynostratigraphy, Karoo Supergroup (Permian and Triassic), mid-Zambezi Valley, southern Zambia. 1997. Nyambe. Imasiku A.. Utting. John. Journal of African Earth Sciences. 24. 4. 563. 1997JAfES..24..563N .
7. 10.1016/S0899-5362(96)00049-8. New palynological data from Karoo sediments, Mana Pools basin, northern Zimbabwe. 1996. d'Engelbronner. E.R.. Journal of African Earth Sciences. 23. 1. 17–30. 1996JAfES..23...17D .
8. 10.1016/j.jafrearsci.2005.07.007. The Karoo basins of south-central Africa. 2005. Catuneanu. O.. Wopfner. H.. Eriksson. P.G.. Cairncross. B.. Rubidge. B.S.. Smith. R.M.H.. Hancox. P.J.. Journal of African Earth Sciences. 43. 1–3. 211–253. 2005JAfES..43..211C .
9. 10.1007/s10040-007-0191-z. Geophysical and hydrogeologic investigation of groundwater in the Karoo stratigraphic sequence at Sawmills in northern Matabeleland, Zimbabwe: A case history. 2007. Danielsen. Jens E.. Dahlin. Torleif. Owen. Richard. Mangeya. Pride. Auken. Esben. Hydrogeology Journal. 15. 5. 945. 2007HydJ...15..945D .