Geochemical and Sr-Nd isotopic characteristics and pressure-temperature estimates of mantle xenoliths from the French Massif Central: Evidence for melting and multiple metasomatism by silicate-rich carbonatite and asthenospheric melts

M. Yoshikawa, T. Kawamoto, T. Shibata, J. Yamamoto

Research output: Contribution to journalArticlepeer-review

Abstract

Ultramafic xenoliths from Mont Briançon, Ray Pic and Puy Beaunit in the French Massif Central show variable mineral compositions that indicate a residual origin after various degrees of partial melting of a fertile peridotite. Furthermore, trace element and Sr-Nd isotopic variations of clinopyroxenes indicate mixing processes between depleted mantle and enriched components such as asthenospheric melt and silicate carbonatite melt. Pyroxene geothermometer and CO2 geobarometer estimates are 860-1060°C at 0.92-1.10 GPa for Mont Briançon, 930-980 oC at 0.89-1.04 GPa for Ray Pic and 840-940 oC at 0.59-0.71 GPa for Puy Beaunit. From south to north, the xenoliths show the following trends: (1) deeper to shallower origin; (2) more depleted mineral compositions, suggesting higher degrees of partial melting; and (3) more enriched isotopes and trace elements, indicating a mixing process with a silicate-rich carbonatite melt characterized by high H2O and K2O, possibly during Variscan subduction.

Original languageEnglish
Pages (from-to)153-175
Number of pages23
JournalGeological Society Special Publication
Volume337
DOIs
Publication statusPublished - 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Water Science and Technology
  • Ocean Engineering
  • Geology

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