Angwa Sandstone

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. Massive Sandstone Mb. [1]
Underlies	Pebbly Arkose Formation
Overlies	Lower Karoo Group
Lithology
Primary	Sandstone
Other	Siltstone
Location
Coordinates	16°06′25″S30°18′25″E / 16.107°S 30.307°E / -16.107; 30.307 [1]
Country	Mozambique, Zambia, Zimbabwe
Type section
Named for	Angwa River, Zimbabwe
Named by	P.M. Oesterlen, Zimbabwe Geological Survey [2]
Angwa Sandstone (Zimbabwe)

The Angwa Sandstone is a geological formation of the mid-Triassic Cabora Bassa Basin ^[1] and Mana Pools Basin ^[3] of southern Africa, consisting mainly of sandstone. ^[4]

Description

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. ^[1]

The Angwa Sandstone has been correlated to the Molteno Formation of the Great Karoo Basin, South Africa, ^{[6] [1]} and to the Escarpment Grit of the Mid-Zambezi Basin. ^[7]

Lithology

The formation is a sedimentary unit, consisting mainly of fluvial sands and silts. ^[1]

It has been dated as covering rocks from much of the Triassic, with pollen and flora identified from the Induan, and Ladinian to Norian. ^{[6] [8]}

Occurrence

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

Fossil Content

Pinales of the Angwa Sandstone
Genus	Presence	Notes	Images
Dadoxylon	Mbire District and Chirundu, Zimbabwe	[2] [9]

Callistophytaceae (Pteridospermopsida) of the Angwa Sandstone
Genus	Presence	Notes	Images
Lepidopteris	Manyima River, Mbire District, Zimbabwe	[8]
Dicroidium	Manyima River, Mbire District, Zimbabwe	[8]

Ginkgoales of the Angwa Sandstone
Genus	Presence	Notes	Images
Sphenobaiera	Manyima River, Mbire District, Zimbabwe	[8]

References

1. 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.
2. 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.
3. Oesterlem, P.M. (2001). "New geological results from the Mana Pools basin of Zimbabwe, Lower Zambezi Graben". Annals of the Zimbabwe Geological Survey. 16: 17–26. Retrieved 15 January 2024.
4. 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 (1): 65–88. Bibcode:2009SAJG..112...65M. doi:10.2113/gssajg.112.1.65.
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. 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.
7. 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.
8. 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.
9. D. Love (1997). "The geology of the Chirundu area, Zambezi Valley". Annals of the Zimbabwe Geological Survey. 18: 18–26.