Kalahari Craton

Last updated
Approximate location of Mesoproterozoic (older than 1.3 Ga) cratons in South America and Africa. Cratons West Gondwana.svg
Approximate location of Mesoproterozoic (older than 1.3 Ga) cratons in South America and Africa.

The Kalahari Craton is a craton, an old and stable part of the continental lithosphere, that occupies large portions of South Africa, Botswana, Namibia and Zimbabwe. It consists of two cratons separated by the Limpopo Belt: the larger Kaapvaal Craton to the south and the smaller Zimbabwe Craton to the north. The Namaqua Belt is the southern margin of the Kaapvaal Craton. [1]

Contents

Parts of the Kalahari Craton are now in East Antarctica (the Grunehogna Craton) and West Antarctica (Haag Nunataks) and the Falkland Islands. [2] The name was introduced by Clifford 1970. [3]

Formation

Following a terminology introduced in 2008, [3] the Archaean-Palaeoproterozoic core of the craton is called the Proto-Kalahari Craton. This core plus accreted Mesoproterozoic crust and dispersed non-African fragments compose the Kalahari Craton. Before the Pan-African Orogeny, the Kalahari Craton was much larger than it is today, but its sutures and therefore its extent are difficult to locate due to later overprinting. [3]

The Kaapvaal Craton, Zimbabwe Craton, and Limpopo Belt are made of Archaean terranes and contain crust at least 3.2 Ga and are underlain by a thick (250 km (160 mi)) layer of buoyant mantle that is producing garnets and diamonds. [1]

During the Palaeoproterozoic the northwest margin of the Archaean core grew by accretion and had formed a Proto-Kalahari Craton by 1.75 Ga. During the period 1.4–1.0 Ga subduction occurred along the northwest margin followed by continental collisions along the eastern and southern margins. By this time enough Mesoproterozoic crust had accreted to transform the Kalahari Craton. At 1.11 Ga, during the assembly of the supercontinent Rodinia, the Kalahari Craton was affected by the Umkondo-Borg Large Igneous Province. [2] At c. 1.15–.98 Ga the Kalahari Craton collided with the eastern margin of Laurentia. [4]

See also

Related Research Articles

Rodinia was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago and broke up 750–633 million years ago. Valentine & Moores 1970 were probably the first to recognise a Precambrian supercontinent, which they named 'Pangaea I'. It was renamed 'Rodinia' by McMenamin & McMenamin 1990 who also were the first to produce a reconstruction and propose a temporal framework for the supercontinent.

<span class="mw-page-title-main">Columbia (supercontinent)</span> Ancient supercontinent of approximately 2,500 to 1,500 million years ago

Columbia, also known as Nuna or Hudsonland, was one of Earth's ancient supercontinents. It was first proposed by John J.W. Rogers and M. Santosh in 2002 and is thought to have existed approximately 2,500 to 1,500 million years ago, in the Paleoproterozoic Era. The assembly of the supercontinent was likely completed during global-scale collisional events from 2100 to 1800 million years ago.

<span class="mw-page-title-main">Arctica</span> Ancient continent in the Neoarchean era

Arctica, or Arctida was an ancient continent which formed approximately 2.565 billion years ago in the Neoarchean era. It was made of Archaean cratons, including the Siberian Craton, with its Anabar/Aldan shields in Siberia, and the Slave, Wyoming, Superior, and North Atlantic cratons in North America. Arctica was named by Rogers 1996 because the Arctic Ocean formed by the separation of the North American and Siberian cratons. Russian geologists writing in English call the continent "Arctida" since it was given that name in 1987, alternatively the Hyperborean craton, in reference to the hyperboreans in Greek mythology.

<span class="mw-page-title-main">Pannotia</span> Hypothesized Neoproterozoic supercontinent from the end of the Precambrian

Pannotia, also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neoproterozoic supercontinent that formed at the end of the Precambrian during the Pan-African orogeny, during the Cryogenian period and broke apart 560 Ma with the opening of the Iapetus Ocean, in the late Ediacaran and early Cambrian. Pannotia formed when Laurentia was located adjacent to the two major South American cratons, Amazonia and Río de la Plata. The opening of the Iapetus Ocean separated Laurentia from Baltica, Amazonia, and Río de la Plata. In 2022 the whole concept of Pannotia was put into question by scientists who argue its existence is not supported by geochronology; "the supposed landmass had begun to break up well before it was fully assembled".

<span class="mw-page-title-main">Baltica</span> Late-Proterozoic to early-Palaeozoic continent

Baltica is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains. The thick core of Baltica, the East European Craton, is more than three billion years old and formed part of the Rodinia supercontinent at c.Ga.

<span class="mw-page-title-main">Congo Craton</span> Precambrian craton that with four others makes up the modern continent of Africa

The Congo Craton, covered by the Palaeozoic-to-recent Congo Basin, is an ancient Precambrian craton that with four others makes up the modern continent of Africa. These cratons were formed between about 3.6 and 2.0 billion years ago and have been tectonically stable since that time. All of these cratons are bounded by younger fold belts formed between 2.0 billion and 300 million years ago.

The Pan-African orogeny was a series of major Neoproterozoic orogenic events which related to the formation of the supercontinents Gondwana and Pannotia about 600 million years ago. This orogeny is also known as the Pan-Gondwanan or Saldanian Orogeny. The Pan-African orogeny and the Grenville orogeny are the largest known systems of orogenies on Earth. The sum of the continental crust formed in the Pan-African orogeny and the Grenville orogeny makes the Neoproterozoic the period of Earth's history that has produced most continental crust.

<span class="mw-page-title-main">Vaalbara</span> Archaean supercontinent from about 3.6 to 2.7 billion years ago

Vaalbara is a hypothetical Archean supercontinent consisting of the Kaapvaal Craton and the Pilbara Craton. E. S. Cheney derived the name from the last four letters of each craton's name. The two cratons consist of crust dating from 2.7 to 3.6 Gya, which would make Vaalbara one of Earth's earliest supercontinents.

<span class="mw-page-title-main">Slave Craton</span> Archaean craton in the north-western Canadian Shield, in Northwest Territories and Nunavut

The Slave Craton is an Archaean craton in the north-western Canadian Shield, in Northwest Territories and Nunavut. The Slave Craton includes the 4.03 Ga-old Acasta Gneiss which is one of the oldest dated rocks on Earth. Covering about 300,000 km2 (120,000 sq mi), it is a relatively small but well-exposed craton dominated by ~2.73–2.63 Ga greenstones and turbidite sequences and ~2.72–2.58 Ga plutonic rocks, with large parts of the craton underlain by older gneiss and granitoid units. The Slave Craton is one of the blocks that compose the Precambrian core of North America, also known as the palaeocontinent Laurentia.

<span class="mw-page-title-main">Sarmatian Craton</span> The southern part of the East European Craton or Baltica, also known as Scythian Plateau

The Sarmatian Craton or Sarmatia is the southern segment/region of the East European Craton or Baltica, also known as Scythian Plateau. The craton contains Archaean rocks 2.8 to 3.7 billion years old (Ga). During the Carboniferous the craton was rifted apart by the Dnieper-Donets rift. As a result, geomorphologically the cratonic area is split by the Donbas Fold Belt, also known as a part of the large Pripyat-Dniepr-Donets aulacogen, which transects Sarmatia, dividing it into the Ukrainian Massif or shield on the southwest and the Voronezh Massif to the northeast.

<span class="mw-page-title-main">Kaapvaal Craton</span> Archaean craton, possibly part of the Vaalbara supercontinent

The Kaapvaal Craton, along with the Pilbara Craton of Western Australia, are the only remaining areas of pristine 3.6–2.5 Ga crust on Earth. Similarities of rock records from both these cratons, especially of the overlying late Archean sequences, suggest that they were once part of the Vaalbara supercontinent.

<span class="mw-page-title-main">Zimbabwe Craton</span> Area in Southern Africa of ancient continental crust

The Zimbabwe Craton is an area in Southern Africa of ancient continental crust, being a part of the ancient continent of Western Gondwana, with rocks dating back to the early Archean Eon, possibly as early as 3.46 billion years ago (Ga.). The craton is named after the country of Zimbabwe where the majority of the craton is. The rocks of the Zimbabwe Craton are separated from the rocks of the Kaapvaal Craton to the southeast by the 250 kilometres (160 mi) wide Limpopo Belt of granulite facies tectonites. The Limpopo belt formed contemporaneously with the Zimbabwe and Kaapvaal cratons, but remained geologically active until much later. It was only in the late Archean, ca. 2.8-2.5 Ga., that the two cratons were stabilized together and that high-grade metamorphism ceased in the Limpopo Belt. North of the Zimbabwe Craton is the Zambezi Belt.

<span class="mw-page-title-main">Barberton Greenstone Belt</span> Ancient granite-greenstone terrane in South Africa

The Barberton Greenstone Belt is situated on the eastern edge of the Kaapvaal Craton in South Africa. It is known for its gold mineralisation and for its komatiites, an unusual type of ultramafic volcanic rock named after the Komati River that flows through the belt. Some of the oldest exposed rocks on Earth are located in the Barberton Greenstone Belt of the Eswatini–Barberton areas and these contain some of the oldest traces of life on Earth, second only to the Isua Greenstone Belt of Western Greenland. The Makhonjwa Mountains make up 40% of the Baberton belt. It is named after the town Barberton, Mpumalanga.

<span class="mw-page-title-main">Limpopo Belt</span>

The Limpopo Belt is located in South Africa and Zimbabwe, runs E-NE, and joins the Kaapvaal Craton to the south with the Zimbabwe Craton to the north. The belt is of high-grade metamorphic rocks that have undergone a long cycle of metamorphism and deformation that ended 2.0 billion years ago, after the stabilisation of the adjacent massifs. The belt comprises 3 components: the Central Zone, the North Marginal Zone and the South Marginal Zone.

<span class="mw-page-title-main">Wyoming Craton</span> Craton in the west-central United States and western Canada

The Wyoming Craton is a craton in the west-central United States and western Canada – more specifically, in Montana, Wyoming, southern Alberta, southern Saskatchewan, and parts of northern Utah. Also called the Wyoming Province, it is the initial core of the continental crust of North America.

<span class="mw-page-title-main">Ur (continent)</span> Hypothetical archaean supercontinent from about 3.1 billion years ago

Ur is a hypothetical supercontinent that formed in the Archean 3,100 million years ago.

<span class="mw-page-title-main">Laurentia</span> A large continental craton that forms the ancient geological core of the North American continent

Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and also the northwestern part of Scotland, known as the Hebridean Terrane. During other times in its past, Laurentia has been part of larger continents and supercontinents and itself consists of many smaller terranes assembled on a network of Early Proterozoic orogenic belts. Small microcontinents and oceanic islands collided with and sutured onto the ever-growing Laurentia, and together formed the stable Precambrian craton seen today.

Sharon Mosher is an American geologist. She did her undergraduate work at University of Illinois Urbana-Champaign. After earning an MSc from Brown University, she returned to the University of Illinois to get her PhD in Geology in 1978. Since 2001 she has held the William Stamps Farish Chair at University of Texas, and, since 2009 she has served as the dean of the Jackson School of Geosciences at Texas. In 2013 she became the president of the American Geosciences Institute.

The geology of South Africa is highly varied including cratons, greenstone belts, large impact craters as well as orogenic belts. The geology of the country is the base for a large mining sector that extracts gold, diamonds, iron and coal from world-class deposits. The geomorphology of South Africa consists of a high plateau rimmed to west, south and southeast by the Great Escarpment, and the rugged mountains of the Cape Fold Belt. Beyond this there is strip of narrow coastal plain.

<span class="mw-page-title-main">Yavapai orogeny</span> Mountain building event 1.7 billion years ago in the southwestern United States

The Yavapai orogeny was an orogenic (mountain-building) event in what is now the Southwestern United States that occurred between 1710 and 1680 million years ago (Mya), in the Statherian Period of the Paleoproterozoic. Recorded in the rocks of New Mexico and Arizona, it is interpreted as the collision of the 1800-1700 Mya age Yavapai island arc terrane with the proto-North American continent. This was the first in a series of orogenies within a long-lived convergent boundary along southern Laurentia that ended with the ca. 1200–1000 Mya Grenville orogeny during the final assembly of the supercontinent Rodinia, which ended an 800-million-year episode of convergent boundary tectonism.

References

  1. 1 2 Zeh, Gerdes & Barton Jr 2009 , Kalahari Craton, pp. 934–935
  2. 1 2 Jacobs et al. 2008 , Abstract
  3. 1 2 3 Jacobs et al. 2008 , Introduction, pp. 2–3
  4. Dalziel, Mosher & Gahagan 2000 , Abstract

Bibliography

  • Clifford, T. N. (1970). "The structural framework of Africa". In Clifford, T.N.; Gass, I.G. (eds.). African magmatism and tectonics. Edinburgh: Oliver and Boyd. pp. 1–26.
  • Dalziel, I. W.; Mosher, S.; Gahagan, L. M. (2000). "Laurentia-Kalahari collision and the assembly of Rodinia". The Journal of Geology. 108 (5): 499–513. doi:10.1086/314418. S2CID   140187051.
  • Jacobs, J.; Pisarevsky, S.; Thomas, R. J.; Becker, T. (2008). "The Kalahari Craton during the assembly and dispersal of Rodinia" (PDF). Precambrian Research. 160 (1–2): 142–158. doi:10.1016/j.precamres.2007.04.022 . Retrieved 11 August 2018.
  • Zeh, A.; Gerdes, A.; Barton Jr, J. M. (2009). "Archean accretion and crustal evolution of the Kalahari Craton—the zircon age and Hf isotope record of granitic rocks from Barberton/Swaziland to the Francistown Arc". Journal of Petrology. 50 (5): 933–966. doi: 10.1093/petrology/egp027 .