Angwa Sandstone

The Angwa Sandstone is a geological formation of the mid-Triassic, consisting mainly of sandstone.[1]

Angwa Sandstone Stratigraphic range: Triassic ~252–210 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Angwa sandstone boulder from Chirundu Hill, Hurungwe District, Zimbabwe
Type	Geological formation
Unit of	Upper Karoo Group, Karoo Supergroup
Sub-units	Alternations Mb. Chirambakadoma Mb.
Underlies	Pebbly Arkose Formation
Overlies	Lower Karoo Group
Lithology
Primary	Sandstone
Other	Siltstone
Location
Coordinates	19.4°S 32.2°E
Country	Mozambique  Zambia  Zimbabwe
Type section
Named for	Angwa River, Zimbabwe
Angwa Sandstone (Zimbabwe)

Geology

The formation is a sedimentary unit, consisting mainly of fluvial sands and silts.[2]

It has been dated as covering rocks from much of the Triassic, with pollen and flora identified from the Induan, and Ladinian to Norian.[3][4]

Stratigraphy

The Angwa Sandstone is the lowest formation in the Upper Karoo Group of the Karoo Supergroup, underlying the Pebbly Arkose Formation and overlying the Lower Karoo Group.[5] The formation is divided into two members: the Alternations Member and the Massive Sandstone (Chirambakadoma) Member.[2]

The Angwa Sandstone has been correlated to the Molteno Formation of the Great Karoo Basin, South Africa,[3][2] and to the Escarpment Grit of the Mid-Zambezi Basin.[6]

Occurrence

The Angwa Sandstone Formation is found in Mozambique, Zambia, Zimbabwe, in the Mana Pools and Cabora Bassa Basins.

Flora

Pinales of the Angwa Sandstone
Taxa	Presence	Notes	Images
Dadoxylon	Mbire District and Chirundu, Zimbabwe	[7][8]

Callistophytaceae (Pteridospermopsida) of the Angwa Sandstone
Taxa	Presence	Notes	Images
Lepidopteris	Manyima River, Mbire District, Zimbabwe	[4]
Dicroidium	Manyima River, Mbire District, Zimbabwe	[4]

Ginkgoales of the Angwa Sandstone
Taxa	Presence	Notes	Images
Sphenobaiera	Manyima River, Mbire District, Zimbabwe	[4]

References

1. Moore, A.E.; Cotterill, F.P.D.; Broderick, T.; Plowes, D. (2009). "Landscape evolution in Zimbabwe from the Permian to present, with implications for kimberlite prospecting". South African Journal of Geology. 112: 65–88. doi:10.2113/gssajg.112.1.65.
2. P. M. Oesterlen; B. D. Millsteed (1994). "Lithostratigraphy, palaeontology, and sedimentary environments of the western Cabora Bassa Basin, lower Zambezi Valley, Zimbabwe". South African Journal of Geology. 97: 205–224.
3. d'Engelbronner, E.R. (1996). "New palynological data from Karoo sediments, Mana Pools basin, northern Zimbabwe". Journal of African Earth Sciences. 23 (1): 17–30. Bibcode:1996JAfES..23...17D. doi:10.1016/S0899-5362(96)00049-8.
4. G. Barale; M. Bamford; B. Gómez; T.J. Broderick; M.A. Raath; A. Cadman (2005). "A fossil peat deposit from the Late Triassic (Carnian) of Zimbabwe with preserved cuticle of Pteridospermopsida and Ginkgoales, and its geological setting". Palaeontologia Africana. 41: 89–100.
5. Oesterlen, P.M.; Blenkinsop, T.G. (1994). "Extension directions and strain near the failed triple junction of the Zambezi and Luangwa Rift zones, southern Africa". Journal of African Earth Sciences. 18 (2): 175. Bibcode:1994JAfES..18..175O. doi:10.1016/0899-5362(94)90029-9.
6. 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 (1–3): 211–253. Bibcode:2005JAfES..43..211C. doi:10.1016/j.jafrearsci.2005.07.007.
7. P.M. Oesterlen (1990). "The geology of the Dande West area (western Cabora Bassa Basin) - a preliminary report". Annals of the Zimbabwe Geological Survey. 14: 12–20.
8. D. Love (1997). "The geology of the Chirundu area, Zambezi Valley". Annals of the Zimbabwe Geological Survey. 18: 18–26.