Contexte de mise en place des roches basiques de la ceinture de roches vertes birimienne de Diagorou-Darbani (Liptako,Niger, Afrique de l'Ouest) : plateau océanique ou environnement d'arc/bassin arrière-arc océanique |
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| Authors: | Amadou Soumaila Philippe Henry Michel Rossy |
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| Institution: | 1. Département de géologie, faculté des sciences, université Abdou Moumouni de Niamey, BP 10662, Niamey, Niger;2. Département de géosciences, UFR Sciences et Techniques, université de Franche-Comté, 16, route de Gray, 25030 Besançon cedex, France |
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| Abstract: | The Diagorou-Darbani Birimian greenstone belt includes (i) tholeiitic metabasalts with flat to slightly depleted LREE patterns, (ii) amphibolites having high contents in both compatible and incompatible elements with strongly fractionated spidergrams showing large HFSE negative anomalies, and (iii) metabasalts and amphibolites with intermediate features between the two previous groups. The chemical compositions of these rocks are not those of oceanic plateau basalts, but suggest a magmatic evolution from an arc environment to a back-arc oceanic basin. Source of the highly enriched amphibolites could be a depleted mantle metasomatized by slab-derived siliceous melts. To cite this article: A. Soumaila et al., C. R. Geoscience 336 (2004). |
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| Keywords: | Liptako Birimien basalte plateau océanique bassin arrière-arc Niger Liptako Birimian basalt oceanic plateau back-arc basin Niger |
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