Forest Sandstone

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Forest Sandstone
Stratigraphic range: Hettangian-Sinemurian
~200–190  Ma
Dune beds Chewore.jpg
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°00′S28°24′E / 20.0°S 28.4°E / -20.0; 28.4
Approximate paleocoordinates 35°00′S5°06′E / 35.0°S 5.1°E / -35.0; 5.1
Region South-central Africa
CountryFlag of Botswana.svg  Botswana
Flag of Zambia.svg  Zambia
Flag of Zimbabwe.svg  Zimbabwe
Type section
Named forForests of Nyamandlovu District, Zimbabwe
Named byA.M. MacGregor, Zimbabwe Geological Survey
Zimbabwe relief location map.jpg
Blue pog.svg
Forest Sandstone (Zimbabwe)

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.

Contents

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
GenusSpeciesPresenceNotesImages
  • unknown protosuchid crocodile [10]
indeterminateGeographically located in Matabeleland North, Zimbabwe.
Sphenodontia of the Forest Sandstone Formation
GenusSpeciesPresenceNotesImages
indeterminateUnspecified, Zimbabwe
Sauropodomorphs of the Forest Sandstone Formation
GenusSpeciesPresenceNotesImages
  1. M. carinatus [11]
Geographically located in Matabeleland North, Zimbabwe. [11]
Massospondylus BW.jpg
  1. V. karibaensis
Geographically located in the Bumi Hills area and the Sibilobilo Islands, in Kariba (District), Mashonaland West, ZimbabwePartial skeleton and scapula
  1. Indeterminate remains [11]
Geographically located in Matabeleland North, Zimbabwe. [11]
Theropods of the Forest Sandstone Formation
GenusSpeciesPresenceNotesImages
  1. M. rhodesiensis [11]
Geographically located in Nyamandhlovu area, Tsholotsho District, Matabeleland North, Zimbabwe. [11] Note: Referred to as Syntarsus by Weishampel et al. [11]
Coelophysis rhodesiensis.JPG

Economic importance

Hydrogeology

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

Related Research Articles

<span class="mw-page-title-main">Karoo Supergroup</span> Mesozoic stratigraphic unit in Africa

The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a period of about 120 million years.

<span class="mw-page-title-main">Beaufort Group</span> Third of the main subdivisions of the Karoo Supergroup in South Africa

The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underlies the Stormberg Group. Based on stratigraphic position, lithostratigraphic and biostratigraphic correlations, palynological analyses, and other means of geological dating, the Beaufort Group rocks are considered to range between Middle Permian (Wordian) to Early Triassic (Anisian) in age.

<i>Daptocephalus</i> Assemblage Zone Biozone of fossils

The Daptocephalus Assemblage Zone is a tetrapod assemblage zone or biozone found in the Adelaide Subgroup of the Beaufort Group, a majorly fossiliferous and geologically important Group of the Karoo Supergroup in South Africa. This biozone has outcrops located in the upper Teekloof Formation west of 24°E, the majority of the Balfour Formation east of 24°E, and the Normandien Formation in the north. It has numerous localities which are spread out from Colesberg in the Northern Cape, Graaff-Reniet to Mthatha in the Eastern Cape, and from Bloemfontein to Harrismith in the Free State. The Daptocephalus Assemblage Zone is one of eight biozones found in the Beaufort Group and is considered Late Permian (Lopingian) in age. Its contact with the overlying Lystrosaurus Assemblage Zone marks the Permian-Triassic boundary.

<span class="mw-page-title-main">Ecca Group</span> Second of the main subdivisions of the Karoo Supergroup of geological strata in southern Africa

The Ecca Group is the second of the main subdivisions of the Karoo Supergroup of geological strata in southern Africa. It mainly follows conformably after the Dwyka Group in some sections, but in some localities overlying unconformably over much older basement rocks. It underlies the Beaufort Group in all known outcrops and exposures. Based on stratigraphic position, lithostratigraphic correlation, palynological analyses, and other means of geological dating, the Ecca Group ranges between Early to earliest Middle Permian in age.

<span class="mw-page-title-main">Clarens Formation</span> Geological formation of the Stormberg Group in southern Africa

The Clarens Formation is a geological formation found in several localities in Lesotho and in the Free State, KwaZulu-Natal, and Eastern Cape provinces in South Africa. It is the uppermost of the three formations found in the Stormberg Group of the greater Karoo Supergroup rocks and represents the final phase of preserved sedimentation of the Karoo Basin.

<span class="mw-page-title-main">Batoka Formation</span> Geological formation in Southern Africa

The Batoka Formation is a geological formation in the Zambezi valley in Botswana, Zambia and Zimbabwe. It is predominantly a volcanic unit comprising mainly basalts. It was formerly thought to contain sand stones containing the dinosaur Vulcanodon, however this was shown to be in error resulting from interpreting folding of the rocks as separate layers, with the sandstone layers actually being from the underlying Forest Sandstone.

<span class="mw-page-title-main">Molteno Formation</span> Triassic geological formation in the Stormberg Group in Lesotho and South Africa

The Molteno Formation is a geological formation found in several localities in Lesotho and South Africa. It lies mainly south of Maseru, near Burgersdorp, Aliwal North, Dordrecht, Molteno, and Elliot. It extends as far north as Matatiele in the Eastern Cape. The formation's localities lie along the Drakensberg Mountains in Kwazulu-Natal, and near Ladybrand in the Free State of South Africa. The Molteno Formation is the lowermost of the three formations in the Stormberg Group of the greater Karoo Supergroup. The Molteno Formation represents the initial phase of preserved sedimentation of the Stormberg Group.

<span class="mw-page-title-main">Pebbly Arkose Formation</span>

The Pebbly Arkose Formation is a Late Triassic geologic formation found in southern Africa.

<span class="mw-page-title-main">Stormberg Group</span> Triassic/Jurassic geological group in the Karoo Supergroup in South Africa

The Stormberg Group is one of the four geological groups that comprises the Karoo Supergroup in South Africa. It is the uppermost geological group representing the final phase of preserved sedimentation of the Karoo Basin. The Stormberg Group rocks are considered to range between Lower Triassic (Olenekian) to Lower Jurassic (Pliensbachian) in age. These estimates are based on means of geological dating including stratigraphic position, lithostratigraphic and biostratigraphic correlations, and palynological analyses.

<span class="mw-page-title-main">Dwyka Group</span> Geological group in the Karoo Supergroup from South Africa

The Dwyka Group is one of four geological groups that compose the Karoo Supergroup. It is the lowermost geological group and heralds the commencement of sedimentation of the Karoo Supergroup. Based on stratigraphic position, lithostratigraphic correlation and palynological analyses, these lowermost Karoo strata range between the Late Carboniferous (Pennsylvanian) to Early Permian in age.

<span class="mw-page-title-main">Abrahamskraal Formation</span> Geological formation of the Beaufort Group in South Africa

The Abrahamskraal Formation is a geological formation and is found in numerous localities in the Northern Cape, Western Cape, and the Eastern Cape of South Africa. It is the lowermost formation of the Adelaide Subgroup of the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup. It represents the first fully terrestrial geological deposits of the Karoo Basin. Outcrops of the Abrahamskraal Formation are found from the small town Middelpos in its westernmost localities, then around Sutherland, the Moordenaarskaroo north of Laingsburg, Williston, Fraserburg, Leeu-Gamka, Loxton, and Victoria West in the Western Cape and Northern Cape. In the Eastern Cape outcrops are known from Rietbron, north of Klipplaat and Grahamstown, and also southwest of East London.

<span class="mw-page-title-main">Angwa Sandstone</span>

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

The Escarpment Grit is a Triassic geologic formation. It is also referred to as the Nyoka Grit.

<span class="mw-page-title-main">Upper Karoo Group</span> Sequence of Triassic to Early Jurassic rocks in southern Africa

The Upper Karoo Group is a sequence of Triassic to Early Jurassic sedimentary and volcanic rocks found in Botswana, Zambia, and Zimbabwe.

<span class="mw-page-title-main">Lower Karoo Group</span>

The Lower Karoo Group is a sequence of late Carboniferous and Permian sandstone sedimentary rocks of the Karoo Supergroup, found in Botswana, Zambia, Zimbabwe, and Mozambique.

The Ellisras Basin is a geological basin that spans the border between South Africa and Botswana, extending west from the town of Lephalale in Limpopo province. Basin fill consists of sedimentary rocks of the Karoo Supergroup, with maximum thickness of 1,500 metres (4,900 ft).

<span class="mw-page-title-main">Balfour Formation</span> Geological formation in the Beaufort Group of South Africa

The Balfour Formation is a geological formation that is found in the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup in South Africa. The Balfour Formation is the uppermost formation of the Adelaide Subgroup which contains all the Late Permian - Early Triassic aged biozones of the Beaufort Group. Outcrops and exposures of the Balfour Formation are found from east of 24 degrees in the highest mountainous escarpments between Beaufort West and Fraserburg, but most notably in the Winterberg and Sneeuberg mountain ranges near Cradock, the Baviaanskloof river valley, Graaff-Reniet and Nieu Bethesda in the Eastern Cape, and in the southern Free State province.

<span class="mw-page-title-main">Katberg Formation</span> Geological formation in the Beaufort Group of the Karoo Supergroup in South Africa

The Katberg Formation is a geological formation that is found in the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup in South Africa. The Katberg Formation is the lowermost geological formation of the Tarkastad Subgroup which contains the Lower to Middle Triassic-aged rocks of the Beaufort Group. Outcrops and exposures of the Katberg Formation are found east of 24 degrees onwards and north of Graaff-Reniet, Nieu Bethesda, Cradock, Fort Beaufort, Queensdown, and East London in the south, and ranges as far north as Harrismith in deposits that form a ring around the Drakensberg mountain ranges.

<span class="mw-page-title-main">Middleton Formation</span> Late middle Permian geological formation in the Eastern Cape

The Middleton Formation is a geological formation that extends through the Northern Cape, Western Cape, and Eastern Cape provinces of South Africa. It overlies the lower Abrahamskraal Formation, and is the eastern correlate, East of 24ºE, of the Teekloof Formation. Outcrops and exposures of the Middleton Formation range from Graaff-Reinet in the Eastern Cape onwards. The Middleton Formation's type locality lies near the small hamlet, Middleton, approximately 25 km south of Cookhouse. Other exposures lie in hillsides along the Great Fish River in the Eastern Cape. The Middleton Formation forms part of the Adelaide Subgroup of the Beaufort Group, which itself forms part of the Karoo Supergroup.

<i>Musankwa</i> Genus of sauropodomorph dinosaurs

Musankwa is an extinct genus of massopodan sauropodomorph dinosaur from the Late Triassic (Norian) Pebbly Arkose Formation of Zimbabwe. The genus contains a single species, M. sanyatiensis, known from a partial leg. Musankwa represents the fourth dinosaur genus to be named from Zimbabwe.

References

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  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. 1 2 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. 1 2 3 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. 1 2 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.
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