Abstract
The southern Guinean terranes belong to the “Rokelide belt” that is located in the southwestern part of the West African craton (Senegal to Liberia). Field investigations and K–Ar and 40Ar–39Ar radiometric analysis performed on samples collected from southern Guinea provide a new interpretation for metamorphic terranes not yet dated. A K–Ar whole-rock age of a gneiss and 40Ar–39Ar plateau ages of amphiboles separated from a mylonitic gneiss of the Ouankifondi formation and a gneiss from the Kissi-Kissi formation yield several Pan-African metamorphic ages at circa 650, 560, and 530 Ma, respectively. Field investigations show that these formations are unconformably capped by the Kolente group. The previous structural framework and the geodynamic evolution of the Rokelide belt based on the coeval evolution of the Ouankifondi and Kissi-Kissi formations and the Kolente group are reassessed. The Rokelide belt is linked to the Bassaride belt. Correlations with adjacent Sierra Leonean terranes and with northern Guinea and Senegal are considered.
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Acknowledgments
We acknowledge the BRGM and the Guinean Ministry of Geology and Mines that support our 2003 field trip. Thanks to Oceane Stchetinine for drawing of figures.
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Villeneuve, M., Bellon, H., Corsini, M. et al. New investigations in southwestern Guinea: consequences for the Rokelide belt (West Africa). Int J Earth Sci (Geol Rundsch) 104, 1267–1275 (2015). https://doi.org/10.1007/s00531-014-1138-y
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DOI: https://doi.org/10.1007/s00531-014-1138-y