Paleoproterozoic high 13C dolomites from the Lastoursville and Franceville basins (SE Gabon) stratigraphy and sedimentary subsidence implications - Archive ouverte HAL Accéder directement au contenu
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Paleoproterozoic high 13C dolomites from the Lastoursville and Franceville basins (SE Gabon) stratigraphy and sedimentary subsidence implications

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Résumé

With the discovery in the 1970s of two-billion year old nuclear reactor in Oklo, Gabon, the Paleoproterozoic of the Franceville basin (Gabon), neglected for many years, attracted the attention of the international community. This led to the intensive study of the basin for about ten years. Between 2006 and the present time, our studies have focused on the interaction between the Paleoproterozoic sediment filling (Francevillian) and tectonics. The work has been done in the frame of a large mapping project sponsored by the European Union (SYSMIN funds). Here we have reviewed the lithostratigraphy of the Francevillian and carbonate rocks of this series for a sedimentological and stable isotope study. Although the Francevillian series has been known for a long time, many difficulties, including access in the region, prevented such a scientific study. Our analysis establishes the palaeoenvironments of deposition with the first report of a sebkha series in the Francevillian, and also reveals a large positive excursion of carbon-13 in the carbonates. This excursion is known on a worldwide scale in the 2.22-2.06 Ga time interval and is reported here for the first time in Gabon. The detailed analysis of this excursion coupled with the lithostratigraphy has considerable consequence on the regional stratigraphy and on the functioning of the basins or sub-basins which were drived by differential subsidence regimes. The inferred time interval of the excursion is in good agreement with the ages obtained from new radiometric dating of the series.
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Dates et versions

hal-00664378 , version 1 (02-02-2012)

Identifiants

  • HAL Id : hal-00664378 , version 1

Citer

Alain Préat, Pascal Bouton, Denis Thiéblemont, Jean-Pierre Prian, Serge Simo Ndounze, et al.. Paleoproterozoic high 13C dolomites from the Lastoursville and Franceville basins (SE Gabon) stratigraphy and sedimentary subsidence implications. Geol. Soc. America (GSA) annual Meeting, Oct 2010, Denver, United States. ⟨hal-00664378⟩

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