Forest Sandstone

The Forest Sandstone is a geological formation in southern Africa, dating to roughly between 200 and 190 million years ago and covering the Hettangian to Sinemurian stages of the Jurassic Period in the Mesozoic Era.^[1] As its name suggests, it consists mainly of sandstone.

Forest Sandstone
Stratigraphic range: Hettangian-Sinemurian ~200–190 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Dune beds in the Forest Sandstone, Chewore Safari Area, Hurungwe District, Zimbabwe
Type	Geological formation
Unit of	Karoo Supergroup  Upper Karoo Group
Underlies	Batoka Formation
Overlies	Pebbly Arkose Formation
Lithology
Primary	Sandstone
Location
Coordinates	20.0°S 28.4°E / -20.0; 28.4
Approximate paleocoordinates	35.0°S 5.1°E / -35.0; 5.1
Region	South-central Africa
Country	Botswana  Zambia  Zimbabwe
Type section
Named for	Forests of Nyamandlovu District, Zimbabwe
Named by	A.M. MacGregor, Zimbabwe Geological Survey
Forest Sandstone (Zimbabwe)

Fossils of the prosauropod dinosaur Massospondylus and the primitive sauropod Vulcanodon have been recovered from the Forest Sandstone.

Geology

Description

The formation is a sedimentary unit, consisting mainly of aeolian sands and silts with interbedded fluvial sediments,^[2] laid down during a period of increasing aridity.^[3]

Extent

The Forest Sandstone is found in Botswana, Zambia and Zimbabwe, in the Mid-Zambezi, Mana Pools, Cabora Bassa and Limpopo Basins,^[4][5][6][7] with its greatest thickness in the Cabora Bassa Basin.^[8]

Deposition

Age

The formation is dated at 200 to 190 Ma.^[1]

Stratigraphy

The Forest Sandstone is the penultimate formation in the Upper Karoo Group of the Karoo Supergroup, lying above the Pebbly Arkose Formation and below the Batoka Formation.^[7] In the Thuli Basin it is sometimes referred to as the Samkoto Formation.^[9]

The Forest Sandstone has been correlated to the Clarens Formation of the Great Karoo Basin in South Africa.^[5][7][8]

Fossil content

Vertebrate fauna

Protosuchia
Genus	Species	Presence	Notes	Images
unknown protosuchid crocodile[10]	indeterminate	Geographically located in Matabeleland North, Zimbabwe.

Sphenodontia of the Forest Sandstone Formation
Genus	Species	Presence	Notes	Images
unknown, similar to Clevosaurus[10]	indeterminate	Unspecified, Zimbabwe

Sauropodomorphs of the Forest Sandstone Formation
Genus	Species	Presence	Notes	Images
Massospondylus[11]	M. carinatus[11]	Geographically located in Matabeleland North, Zimbabwe.[11]
Vulcanodon[12][13]	V. karibaensis	Geographically located in the Bumi Hills area and the Sibilobilo Islands, in Kariba (District), Mashonaland West, Zimbabwe	Partial skeleton and scapula
Prosauropoda[11]	Indeterminate remains[11]	Geographically located in Matabeleland North, Zimbabwe.[11]

Theropods of the Forest Sandstone Formation
Genus	Species	Presence	Notes	Images
Megapnosaurus[11]	M. rhodesiensis[11]	Geographically located in Nyamandhlovu area, Tsholotsho District, Matabeleland North, Zimbabwe.[11]	Note: Referred to as Syntarsus by Weishampel et al.[11]

Economic importance

Hydrogeology

The Forest Sandstone is the major groundwater-bearing unit of the Upper Karoo Group.^[14]

References

1. "Forest Sandstone Formation". Paleobiology Database. Retrieved 2010-01-03.
2. 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. S2CID 2059067.
3. Maurice E. Tucker; Michael J. Benton (1982). "Triassic environments, climate and reptile evolution" (PDF). Palaeogeography, Palaeoclimatology, Palaeoecology. 40 (4): 361–379. Bibcode:1982PPP....40..361T. doi:10.1016/0031-0182(82)90034-7. Archived from the original (PDF) on 2009-01-26. Retrieved 2010-01-08.
4. 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.
5. 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.
6. Jones, D. L.; Duncan, R. A.; Briden, J. C.; Randall, D. E.; MacNiocaill, C. (2001). "Age of the Batoka basalts, northern Zimbabwe, and the duration of Karoo Large Igneous Province magmatism". Geochemistry, Geophysics, Geosystems. 2 (2): n/a. Bibcode:2001GGG.....2.1022J. doi:10.1029/2000GC000110.
7. 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.
8. 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.
9. Rogers, Raymond R.; Rogers, Kristina Curry; Munyikwa, Darlington; Terry, Rebecca C.; Bradley s.Singer (2004). "Sedimentology and taphonomy of the upper Karoo-equivalent Mpandi Formation in the Tuli Basin of Zimbabwe, with a new 40Ar/39Ar age for the Tuli basalts" (PDF). Journal of African Earth Sciences. 40 (3–4): 147. Bibcode:2004JAfES..40..147R. doi:10.1016/j.jafrearsci.2004.11.004.
10. Paul E. Olsen; Peter M. Galton (1984). "A review of the reptile and amphibian assemblages from the Stromberg of southern Africa, with special emphasis on the footprints and age of the Stromberg" (PDF). Palaeont. Afr. 25: 87–110.
11. Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Jurassic, Africa)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 535–536. ISBN 0-520-24209-2.
12. Viglietti, Pia A.; Barrett, Paul M.; Broderick, Tim J.; Munyikwa, Darlington; MacNiven, Rowan; Broderick, Lucy; Chapelle, Kimberley; Glynn, Dave; Edwards, Steve (January 2018). "Stratigraphy of the Vulcanodon type locality and its implications for regional correlations within the Karoo Supergroup". Journal of African Earth Sciences. 137: 149–156. Bibcode:2018JAfES.137..149V. doi:10.1016/j.jafrearsci.2017.10.015. ISSN 1464-343X.
13. M.A. Raath (1972). "Fossil vertebrate studies in Rhodesia: a new dinosaur (Reptilia: Saurischia) from near the Triassic-Jurassic boundary". Arnoldia. 5.
14. Larsen, Flemming; R. Owen; T. Dahlin; P. Mangeya; G. Barmen (2002). "A preliminary analysis of the groundwater recharge to the Karoo formations, mid-Zambezi basin, Zimbabwe" (PDF). Physics and Chemistry of the Earth. 27 (11–22): 765–772. Bibcode:2002PCE....27..765L. doi:10.1016/s1474-7065(02)00064-5. Archived from the original (PDF) on 2011-08-20.