Birimian

Geologic map of the Tarkwa gold district in Ghana showing significant folding and faulting of the Birimian
Geologic map of Birimian outcrops in Mali, at Bougouni and Kenieba

The Birimian rocks are major sources of gold and diamonds that extend through Ghana, Côte d'Ivoire, Guinea, Mali and Burkina Faso. They are named after the Birim River, one of the main tributaries of the Pra River in Ghana and the country's most important diamond-producing area. Ghana and Mali are the second and third largest producers of gold in Africa, respectively.[1]

The Birimian terranes in the southern part of the West African craton are a mix of metamorphosed volcanic, sedimentary, and plutonic rocks and low-grade metavolcanics and metasediments. Almost half of the terranes consist of alkaline granites. The rocks formed over a period of about 50 million years between 2.200 Ga and 2.100 Ga years ago.[2]

  1. ^ "Africa geologically under-exposed". Mining Review Africa. 2004. Archived from the original on December 2, 2008. Retrieved 2009-03-16.
  2. ^ Muriel Boher; Wafa Abouchami; Annie Michard; Francis Albarede; Nicholas T. Arndt. "Crustal Growth in West Africa at 2.1 Ga". American Geophysical Union. Retrieved 2009-03-16.