Les xénolites ultramafiques du volcanisme alcalin quaternaire d'Oranie (Tell,Algérie occidentale), témoins d'une lithosphère cisaillée et enrichieUltramafic xenoliths from Quaternary alkali volcanism from Oranie (Tell,western Algeria): witnesses of a sheared and enriched lithosphere |
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| Authors: | Mohamed Zerka Jean-Yves Cottin Michel Grégoire Jean-Pierre Lorand M&#x;Hamed Megartsi Mohamed Midoun |
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| Institution: | 1. Faculté des sciences de la Terre, université d''Oran, BP 1524, Oran, Algérie;2. Laboratoire de géologie–pétrologie, URA 10 CNRS, université Jean-Monnet, 23, rue du Docteur-Paul-Michelon, 42023 Saint-Etienne cedex, France;3. Département des sciences géologiques, université du Cap, Rondebosch 7701, Afrique du Sud;4. Laboratoire de minéralogie, URA 736 CNRS, Muséum national d''histoire naturelle, 61, rue de Buffon, 75005 Paris, France;5. Faculté des sciences de la Terre, USTHB/Alger, BP 32 El-Alia, Alger, Algérie;6. Centre Francis-Arrighi, Domaine de Valabre, RD 7, 13120 Gardanne, France |
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| Abstract: | Numerous ultramafic xenoliths occur within the A??n–Temouchent volcanic complex (Northwestern Oranie, Algeria). Most of them are type I mantle tectonites (lherzolites and harzburgites) and composite xenoliths (harzburgite/clinopyroxenite) are rare. Only a few samples of spinel lherzolites display relatively fertile compositions when the major part of type I xenoliths have refractory major element compositions but enriched LREE contents showing that they have been affected by mantle metasomatism. The composite xenoliths are witnesses of reactions of alkaline magmas with the upper mantle. An asthenospheric rising, in relation with the large strike slip fault affecting the North African plate margin at Trias time is proposed as a possible geodynamical setting. To cite this article: M. Zerka et al., C. R. Geoscience 334 (2002) 387–394. |
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| Keywords: | xenoliths upper mantle mantle metasomatism lithospheric thinning Oranie Algeria xénolites manteau supérieur métasomatisme mantellique amincissement lithosphérique Oranie Algérie Géomatériaux Pétrologie Geomaterials Petrology |
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