Komatii Formation

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]

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]

• 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.