The Transvaal Supergroup is a

stratigraphic unit A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it ...

in northern South Africa and southern

Botswana Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label=Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalahar ...

, situated on the

Kaapvaal Craton The Kaapvaal Craton (centred on Limpopo Province in South Africa), along with the Pilbara Craton of Western Australia, are the only remaining areas of pristine 3.6–2.5 Ga (billion years ago) crust on Earth. Similarities of rock records fro ...

, roughly between 23 and 29 degrees southern latitude and 22 to 30 degrees eastern longitude. It is dated to the boundary between the

Archean The Archean Eon ( , also spelled Archaean or Archæan) is the second of four geologic eons of Earth's history, representing the time from . The Archean was preceded by the Hadean Eon and followed by the Proterozoic. The Earth Earth ...

and

Proterozoic The Proterozoic () is a geological eon spanning the time interval from 2500 to 538.8million years ago. It is the most recent part of the Precambrian "supereon". It is also the longest eon of the Earth's geologic time scale, and it is subdivided ...

eras, roughly 2,500 Mya. It is delimited by the

Witwatersrand Basin The Witwatersrand () (locally the Rand or, less commonly, the Reef) is a , north-facing scarp in South Africa. It consists of a hard, erosion-resistant quartzite metamorphic rock, over which several north-flowing rivers form waterfalls, which ...

(2,700 Mya) and the

Bushveld Igneous Complex The Bushveld Igneous Complex (BIC) is the largest layered igneous intrusion within the Earth's crust. It has been tilted and eroded forming the outcrops around what appears to be the edge of a great geological basin: the Transvaal Basin. It is ...

(2,050 Mya). It consists of three parts, *the

Transvaal Basin The Transvaal Basin is one of three basins of the Transvaal Supergroup on the Kaapvaal craton. The evolution of this 2.65–2.05 Ga Neoarchaean–Palaeoproterozoic basin is thought to have been derived largely from magmatism, palaeoclimate and e ...

in the east *the Griqualand Basin in the west *the smaller Kanye Basin in southern Botswana. Transvaal sedimentation began with predominantly clastic sedimentary rocks (Black Reef-Vryburg Formations) followed by carbonate rocks and

banded iron formation Banded iron formations (also known as banded ironstone formations or BIFs) are distinctive units of sedimentary rock consisting of alternating layers of iron oxides and iron-poor chert. They can be up to several hundred meters in thickness a ...

s (Chuniespoort-Ghaap-Taupone Groups). After an erosional hiatus, the clastic sedimentary rocks and volcanics of the Pretoria-Postmasburg-Segwagwa Groups were deposited within the three basins, largely under closed-basin conditions. A final stage of predominantly volcanic succession (Rooiberg Group-Loskop Formation) is limited to the Transvaal Basin. The Campbellrand-Malmani carbonate platform is part of the Chuniespoort Group and originally covered all of the Kaapvaal Craton. It has a thickness of over 1 km in both the Malmani and Campbellrand Subgroups. The Malmani Subgroup is situated northwest of Johannesburg. It consists of

dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

and

chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a prec ...

with only minor clastic sediments. Several workers such as an environmentalist, Isaac Chuene, Raymond Ngobeni and Khutso Masemola noted the presence of fossils in the Chunniespoort mountains of the Chunniespoort Group.

References

*Octavian Catuneanu, Patrick G. Eriksson (1999). "The sequence stratigraphic concept and the Precambrian rock record: an example from the 2.7–2.1 Ga Transvaal Supergroup, Kaapvaal craton". ''

Precambrian Research ''Precambrian Research'' is a peer-reviewed scientific journal covering the geology of the Earth and its planetary neighbors. It is published by Elsevier and, , the editors-in-chief are V. Pease (Stockholm University) and G.C. Zhao (University of H ...

'', 97: 215–251. *P. G. Eriksson, P. J. Hattingh, W. Altermann (April 1995). "An overview of the geology of the Transvaal Sequence and Bushveld Complex, South Africa", ''

Mineralium Deposita ''Mineralium Deposita, International Journal for Geology, Mineralogy and Geochemistry of Mineral Deposits '' is a peer-reviewed scientific journal published by Springer Science+Business Media. It is the official journal of the Society for Geology A ...

'', Volume 30, Issue 2, pp 98–111. Geologic formations of South Africa Geological supergroups Archean Africa Proterozoic Africa Paleoproterozoic geology {{Africa-geologic-formation-stub

See also

References