Franceville basin

The Franceville Basin is a 1.6–2.1 billion year old sedimentary basin in Gabon. It contains unmetamorphosed sediments.[1] It is notable for containing the Francevillian Biota, which is likely the oldest multicellular life known. A natural fission reactor formed there about 1.8 - 2.1 billion years ago.[2]

Map of Francevillian basin geology
For other uses, see Francevillian B Formation.

Geology

The Franceville Basin cover approximately 25,000 km2 and is made up of unmetamorphosed sediment derived mainly from eroded Mesoarchaean tonalite–trondhjemite–granodiorites.[3] It is over a kilometer thick, with various sources claiming 2.5-4 kilometers as the maximum depth.[1] Around 1.8-2.1 billion years ago a natural fission reactor formed, nicknamed the "Oklo reactor". The resulting fission by-products were held in place by a clay layer.[2]

See also

References
  1. Bankole, Olabode M.; El Albani, Abderrazak; Meunier, Alain; Gauthier-Lafaye, François (October 2015). "Textural and paleo-fluid flow control on diagenesis in the Paleoproterozoic Franceville Basin, South Eastern, Gabon". Precambrian Research. 268: 115–134. doi:10.1016/j.precamres.2015.07.008.
  2. Gauthier-Lafaye, F.; Holliger, P.; Blanc, P. -L. (1996-12-01). "Natural fission reactors in the Franceville basin, Gabon: A review of the conditions and results of a "critical event" in a geologic system". Geochimica et Cosmochimica Acta. 60 (23): 4831–4852. doi:10.1016/S0016-7037(96)00245-1. ISSN 0016-7037.
  3. Bankole, Olabode M.; El Albani, Abderrazak; Munier, Alain; Poujol, Marc; Bekker, Andrey (15 September 2020). "Elemental geochemistry and Nd isotope constraints on the provenance of the basal siliciclastic succession of the middle Paleoproterozoic Francevillian Group, Gabon". Precambrian Research. 348: 105874. doi:10.1016/j.precamres.2020.105874. S2CID 224896274. Retrieved 13 November 2022.


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