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.

Quick Facts Type, Sub-units ...
Onverwacht Group
Stratigraphic range: Paleoarchean
>3300 Ma
TypeGeological group
Sub-unitsSubunits
UnderliesFig Tree Formation
Thickness16,370 m (53,710 ft)
Lithology
PrimaryGreenstone belt
OtherVolcanic rock
Location
Coordinates25.8°S 31.0°E / -25.8; 31.0
RegionBarberton Greenstone Belt, Mpumalanga
Country South Africa
 Eswatini
ExtentKaapvaal Craton
Thumb
Location of the Barberton Greenstone Belt
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A well known part of the Onverwacht Series is visible in the Komati valley, located in the east of the Transvaal region.

Subdivision

The Onverwacht Group can be divided into two subgroups with six formations:

  • Geluk Subgroup
    • Swartkoppie Formation920 metres (3,020 ft)
    • Kromberg Formation1,920 metres (6,300 ft)
    • Hooggenoeg Formation4,850 metres (15,910 ft)
  • Tjakastad Subgroup
    • Komatii Formation3,500 metres (11,500 ft)
    • Theespruit Formation1,980 metres (6,500 ft)
    • Sandspruit Formation3,200 metres (10,500 ft)

The fossils found in the Onverwacht Series are among the oldest found on Earth.[1]

See also

References

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