Nature du manteau supérieur et processus métasomatiques de part et d'autre du Sillon Mouiller (Massif Central)

Abstract

Peridotite xenoliths collected in two Mio-Pliocene volcanoes on either side of the Sillon Mouiller (French Massif Central) have contrasting characteristics. East of the Sillon Mouiller, the peridotites record anomalously high temperatures (1,250°C) and extensive reequilibration with basaltic melts. To the west, equilibrium temperatures are much lower (950"C) and the peridotites bear evidence for interaction with volatile-rich small melt fractions. In agreement with seismic tomographic data, these results indicate that the Massif Central lithospheric mantle is strongly affected by mantle plume upwelling to the east of the Sillon Mouiller, while this effect is moderate to the west.