Escarpment Grit

Escarpment Grit
Stratigraphic range: Early Triassic
↓
Type Geological formation
Unit of Upper Karoo Group, Karoo Supergroup
Underlies Pebbly Arkose Formation
Overlies Lower Karoo Group
Lithology
Primary Gritstone
Other Sandstone
Type section
Named for Descriptive name
Named by A.M. MacGregor, Zimbabwe Geological Survey

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 (Earloy Triassic).[7]

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

Flora

Alisporites spores have been identified from the Escarpment Grit in north-western Zimbabwe.[8]

Hydrogeology

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

References

  1. ↑ Nyambe, Imasiku A. (1999). "Tectonic and climatic controls on sedimentation during deposition of the Sinakumbe group and Karoo supergroup, in the mid-Zambezi Valley Basin, southern Zambia". Journal of African Earth Sciences 28 (2): 443. Bibcode:1999JAfES..28..443N. doi:10.1016/S0899-5362(99)00014-7.
  2. ↑ Kreuser, T; Wopfner, H; Kaaya, C; Markwort, S; Semkiwa, P; Aslandis, P (1990). "Depositional evolution of permo-triassic karoo basins in Tanzania with reference to their economic potential". Journal of African Earth Sciences 10: 151. Bibcode:1990JAfES..10..151K. doi:10.1016/0899-5362(90)90052-G.
  3. ↑ Nyambe, Imasiku A.; Dixon, Owen (2000). "Sedimentology of the Madumabisa Mudstone Formation (Late Permian), Lower Karoo Group, mid-Zambezi Valley Basin, southern Zambia". Journal of African Earth Sciences 30 (3): 535. Bibcode:2000JAfES..30..535N. doi:10.1016/S0899-5362(00)00037-3.
  4. ↑ Sikatali, C; Njamu, M (1992). "A uranium orientation survey in Sikaneka area, Southern Zambia". Journal of African Earth Sciences 14 (2): 275. Bibcode:1992JAfES..14..275S. doi:10.1016/0899-5362(92)90104-K.
  5. ↑ Bordy, Emese M.; Catuneanu, Octavian (2001). "Sedimentology of the upper Karoo fluvial strata in the Tuli Basin, South Africa". Journal of African Earth Sciences 33 (3–4): 605. Bibcode:2001JAfES..33..605B. doi:10.1016/S0899-5362(01)00090-2.
  6. ↑ 6.0 6.1 Nyambe, Imasiku A.; Utting, John (1997). "Stratigraphy and palynostratigraphy, Karoo Supergroup (Permian and Triassic), mid-Zambezi Valley, southern Zambia". Journal of African Earth Sciences 24 (4): 563. Bibcode:1997JAfES..24..563N. doi:10.1016/S0899-5362(97)00081-X.
  7. ↑ 7.0 7.1 Catuneanu, O.; Wopfner, H.; Eriksson, P.G.; Cairncross, B.; Rubidge, B.S.; Smith, R.M.H.; Hancox, P.J. (2005). "The Karoo basins of south-central Africa". Journal of African Earth Sciences 43: 211. Bibcode:2005JAfES..43..211C. doi:10.1016/j.jafrearsci.2005.07.007.
  8. ↑ 8.0 8.1 d'Engelbronner, E.R. (1996). "New palynological data from Karoo sediments, Mana Pools basin, northern Zimbabwe". Journal of African Earth Sciences 23: 17. Bibcode:1996JAfES..23...17D. doi:10.1016/S0899-5362(96)00049-8.
  9. ↑ Danielsen, Jens E.; Dahlin, Torleif; Owen, Richard; Mangeya, Pride; Auken, Esben (2007). "Geophysical and hydrogeologic investigation of groundwater in the Karoo stratigraphic sequence at Sawmills in northern Matabeleland, Zimbabwe: A case history". Hydrogeology Journal 15 (5): 945. Bibcode:2007HydJ...15..945D. doi:10.1007/s10040-007-0191-z.