Onverwacht Group
Onverwacht Group | |
---|---|
Stratigraphic range: Paleoarchean > | |
Type | Geological group |
Sub-units | Subunits |
Underlies | Fig Tree Formation |
Thickness | 16,370 m (53,710 ft) |
Lithology | |
Primary | Greenstone belt |
Other | Volcanic rock |
Location | |
Coordinates | 25°48′S 31°00′E / 25.8°S 31.0°E |
Region | Barberton Greenstone Belt, Mpumalanga |
Country | South Africa Eswatini |
Extent | Kaapvaal Craton |
Location of the Barberton Greenstone Belt |
The Onverwacht Group or Onverwacht Series is a series of greenstone belts and volcanic rock formations from the Archean Eon in the Kaapvaal Craton in South Africa and Eswatini.
A well known part of the Onverwacht Series is visible in the Komati valley, located in the east of the Transvaal region.
Subdivision
[edit]The Onverwacht Group can be divided into two subgroups with six formations:
- Geluk Subgroup
- Swartkoppie Formation – 920 metres (3,020 ft)
- Kromberg Formation – 1,920 metres (6,300 ft)
- Hooggenoeg Formation – 4,850 metres (15,910 ft)
- Tjakastad Subgroup
- Komatii Formation – 3,500 metres (11,500 ft)
- Theespruit Formation – 1,980 metres (6,500 ft)
- Sandspruit Formation – 3,200 metres (10,500 ft)
The fossils found in the Onverwacht Series are among the oldest found on Earth.[1]
See also
[edit]References
[edit]- ^ Engel et al., 1968
Bibliography
[edit]- Engel, A.E.; Nagy, B.; Nagy, L.A.; Engel, C.G.; Kremp, G.O.; Drew, C.M. (1968). "Alga-Like Forms in Onverwacht Series, South Africa: Oldest Recognized Lifelike Forms on Earth". Science. 161 (3845): 1005–1008. doi:10.1126/science.161.3845.1005. PMID 17812798. S2CID 30694721. Retrieved 12 July 2008.
External links
[edit]- (in German) Der Barberton Greenstone Belt und Komatiite