Characterization of the metasomatic agent in mantle xenoliths from Devès, Massif Central (France) using coupled in situ trace-element and O, Sr and Nd isotopic compositions
S. Touron, C. Renac, S. Y. O'Reilly, J.-Y. Cottin, W. L. Griffin, 2008. "Characterization of the metasomatic agent in mantle xenoliths from Devès, Massif Central (France) using coupled in situ trace-element and O, Sr and Nd isotopic compositions", Metasomatism in Oceanic and Continental Lithospheric Mantle, M. Coltorti, M. Grégoire
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Spinel lherzolites and harzburgites from Mont-Briançon and Marais de Limagne in the Devès volcanic district display coarse-grained to porphyroclastic microstructures and the modal content of volatile-bearing phases increases with the degree of deformation. Clinopyroxene and/or spinel are partly or totally reacted to amphibole. The coupled interpretations of trace-element, rare earth element (REE) and O–Sr–Nd data for clinopyroxene and amphibole indicate that the metasomatized mantle beneath Devès is a mixture of depleted and enriched mantle associated with an alkaline, high field strength element poor, and light rare earth element, U- and Th-rich carbonate-rich silicate fluid–melt metasomatic agent. Oxygen isotope and REE data for clinopyroxene–amphibole pairs indicate a (La/Yb)N enrichment related to an increasing metasomatic agent/rock ratio.