Phlogopite – bearing ultramafic rocks from the Serre massif, Calabrian Peloritan Arc, southern Italy: an example of hybridization between hydrous siliceous melts and peridotites?.

The deepest part of the continental crust of the Calabrian-Peloritan Arc crops out in the northwestern part of the Serre Massif, southern Calabria. It is mainly formed of metagabbroic rocks and pyriclasites. Ultramafic rocks occur either as continuous layer (6-7 meter thick) or as decimetric lenses within metagabbroic rocks. The ultramafic rocks include phlogopite-bearing and orthopyroxene-rich peridotites, and phlogopite-bearing orthopyroxenite. The metagabbroic and ultramafic rocks of the Serre Massif are intruded by trondhjemitic-tonalitic dykes. The occurrence of phlogopite and orthopyroxene-rich portions and veinlets in the peridotites from the Serre Massif indicates that the rocks underwent metasomatic event. The Curinga ultramafic carry a peculiar chemical composition that may be explained as the result of hybridization between a trondhjemitic-tonalitic melt and peridotites. The comparison between the composition of the calculated peridotite- trondhjemite mixtures and that of the Serre peridotites shows that the latters have compositions compatible with mixtures of about 20-30 wt% of trondhjemitic-tonalitic melt, whereas the phlogopite orthopyroxenite corresponds to mixtures up to 50 wt% of the felsic melt.