Komatii Formation

Coordinates: 25°48′S 31°00′E / 25.8°S 31.0°E

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Komati Formation
Stratigraphic range: Paleoarchean 3300 Ma Pha. Proterozoic Archean Had. ↓
Type	Geological formation
Unit of	Onverwacht Group Tjakastad Subgroup
Underlies	Geluk Subgroup Hooggenoeg Formation
Overlies	Theespruit Formation
Thickness	3,500 m (11,500 ft)
Lithology
Primary	Komatiite
Other	Tholeiite
Location
Coordinates	25°48′S 31°00′E / 25.8°S 31.0°E / -25.8; 31.0
Region	Barberton Greenstone Belt, Mpumalanga
Country	South Africa
Extent	Kaapvaal Craton
Type section
Named for	Komati River
Location of the Barberton Greenstone Belt

The Komati Formation, also named as Komatii Formation, is a 3.475 billion year old Paleoarchean rock formation, named after the nearby Komati River in South Africa. It is the type locality for komatiite, a high temperature, magnesium-rich volcanic rock occurring in the Barberton Greenstone Belt, Mpumalanga.^[1]

Description

[edit]

The formation, belonging to the Tjakastad Subgroup of the Onverwacht Group, overlies the Theespruit Formation and is overlain by the Hooggenoeg Formation of the Geluk Subgroup.^[2] Komatiites and tholeiites from the Komati Formation were analyzed for sulfur and provided δ34S values between −0.7 and 5.2 ‰.^[3]

The Komatii Formation comprises metamorphosed komatiites and basaltic komatiites, with minor mafic lavas and small intrusions. The lower part of the Komatii Formation is dominantly ultramafic, while the upper part is dominantly mafic.^[4]

References

[edit]

^ Greenstone Belt Studies, Department of Geological Sciences, University of Cape Town
^ Montinaro et al., 2015, p.314
^ Montinaro et al., 2015, p.319
^ Guice, 2019, p.143

Bibliography

[edit]

Guice, George L (2019). Origin and geodynamic significance of ultramafic-mafic complexes in the North Atlantic and Kaapvaal Cratons (PhD thesis). Cardiff University. pp. 1–289.
Montinaro, Alice; Strauss, Harald; Mason, Paul R.D.; Roerdink, Desiree; Münker, Carsten; Schwarz-Schamper, Ulrich; Arndt, Nicholas T.; Farquhar, James; Beukes, Jens Gutzmer and Marc Peters, Nicolas J. (2015). "Paleoarchean sulfur cycling: Multiple sulfur isotope constraints from the Barberton Greenstone Belt, South Africa". Precambrian Research. 267: 311–322.

Geology of South Africa

Geological formations

List of fossiliferous stratigraphic units in South Africa

Palaeoarchaean	Bushveld Igneous Complex Fig Tree Formation Komatii Formation Moodies Group Onverwacht Group Transvaal Supergroup
Paleozoic	Carboniferous Dwyka Group Ganigobis Formation Devonian Bokkeveld Group Table Mountain Sandstone Permian Abrahamskraal Formation Balfour Formation Dwyka Group Ganigobis Formation Teekloof Formation Whitehill Formation Ordovician Soom Shale
Mesozoic	Cretaceous Uitenhage Group Buffelskloof Formation Enon Formation Kirkwood Formation Sundays River Formation Kalahari Deposits Jurassic Drakensberg Group Enon Formation Uitenhage Group Karoo Supergroup Beaufort Group Abrahamskraal Formation Balfour Formation Katberg Formation Middleton Formation Teekloof Formation Dwyka Group Ecca Group Whitehill Formation Stormberg Group Bushveld Sandstone Clarens Formation Elliot Formation Triassic Elliot Formation Katberg Formation Molteno Formation Normandien Formation
Cenozoic	Algoa Group

‎Tectonics and orogeny

Volcanism	List of volcanoes in South Africa Pilanesberg Pilanesberg Game Reserve Prince Edward Islands Diatremes Big Hole Finsch diamond mine Jagersfontein Mine Koffiefontein mine Barberton Greenstone Belt Drakensberg Karoo-Ferrar
Earthquakes	1620 Robben Island earthquake 1969 Tulbagh earthquake 2006 Mozambique earthquake 2014 Orkney earthquake
Impact craters	Kalkkop crater Morokweng impact structure Tswaing crater Vredefort impact structure
Meteorites	Bellsbank meteorite

‎Mineral deposits
Kimberlite Merensky Reef Witwatersrand Banket (mining term) Coal in South Africa Iron ore in Africa Platinum in Africa Titanium in Africa Uranium in Africa Minerals Council South Africa Department of Mineral Resources (South Africa) Department of Mineral Resources and Energy

Paleontology‎

Ordovician

Devonian

Carboniferous

Permian

Beaufort Group

Assemblages	Cistecephalus Assemblage Zone Daptocephalus Assemblage Zone Eodicynodon Assemblage Zone Pristerognathus Assemblage Zone Tapinocephalus Assemblage Zone Tropidostoma Assemblage Zone

Triassic

Assemblages	Cynognathus Assemblage Zone Lystrosaurus Assemblage Zone

Jurassic

Cretaceous

Paleogene

Nummulite

Neogene

Pleistocene

Other

Research and administration‎

Geologists	Hans Merensky
Paleontologists	Andrew Geddes Bain Lieuwe Dirk Boonstra Charles Kimberlin Brain Robert Broom Alfred Brown Anusuya Chinsamy-Turan H. Basil S. Cooke Alfred W. Crompton Daniel Rossouw Kannemeyer Andre Keyser James Kitching John Talbot Robinson George William Stow Eduard Meine van Zinderen-Bakker

Regional articles
Geology of Cape Town

Other
Pothole (geology) Steep structure Swazian

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