New investigations in southwestern Guinea: consequences for the Rokelide belt (West Africa)

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• 作者：Michel Villeneuve ; Hervé Bellon ; Michel Corsini…
• 关键词：Radiometric ages (K–Ar and 40Ar-9Ar) ; Guinea ; Rokelide belt ; Bassaride belt ; West Africa ; Geodynamic models
• 刊名：International Journal of Earth Sciences
• 出版年：2015
• 出版时间：July 2015
• 年：2015
• 卷：104
• 期：5
• 页码：1267-1275
• 全文大小：4,882 KB
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• 作者单位：Michel Villeneuve (1) r> Hervé Bellon (2) r> Michel Corsini (3) r> Jo?l Le Metour (4) r> Sébastien Chatelee (1) r>r>1. CEREGE, Université d’Aix-Marseille, case 67, 3, place Victor Hugo, 13331, Marseille, France r> 2. UMR CNRS 6538, UBO, IUEM, Université européenne de Bretagne, Place Nicolas Copernic, 29280, Plouzané, France r> 3. Geoazur, Université de Nice-Sophia Antipolis, 250, rue A.Einstein, 06560, Valbonne, France r> 4. BRGM, avenue Claude Guillemin, B.P. 6009, 45060, Orleans Cedex 2, France r>
• 刊物类别：Earth and Environmental Science
• 刊物主题：Earth sciencesr>Geologyr>Geophysics and Geodesyr>
• 出版者：Springer Berlin / Heidelberg
• ISSN：1437-3262

文摘

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-sup>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-sup>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.