Birrimian Group

geological formation, West Africa

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June 22, 2026

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The Birimian Group is a geological formation found in western Africa, primarily in countries like Senegal and Ghana. It is composed of metavolcanic and metasedimentary rocks, along with granitoids, and formed during the early Proterozoic Eon, approximately 2.5 to 1.6 billion years ago. This formation is part of the larger Eburnian orogenic event, which involved significant deformation and metamorphism of rocks, likely due to continental collision. The Birimian terrain is situated in noncratonic areas and is considered a key component of western Africa's Precambrian geology.12

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Precambrian
Greenstones and granites
… in central Canada, in the Birrimian Group in West Africa, and in the Pan-African belts of the Arabian-Nubian Shield. Generally, such rocks resemble those in modern island arcs and back-arc basins, and the presence of remnants of oceanic plateau is suspected.
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… in central Canada, in the Birrimian Group in West Africa, and in the Pan-African belts of the Arabian-Nubian Shield. Generally, such rocks resemble those in modern island arcs and back-arc basins, and the presence of remnants of oceanic plateau is suspected.
Read More