METAMORPHIC XENOLITHS AND MICROGRANULAR ENCLAVES IN THE SERRE GRANODIORITES (SOUTHERN CALABRIA, ITALY) - THEIR CONNECTION WITH GRANITOID GENESIS

Late-hercynian granodiorites in the eastern Serre are calc-alkaline an d peraluminous in composition; actinolitic-hornblende typically occurs in the mafic types, whereas muscovite occurs in the felsic ones. Magm atic microgranular enclaves and small metamorphic xenoliths are presen t in these granitoids. A petrographical study and microprobe analyses on plagioclase, biotite, amphibole, cordierite and cummingtonite in xe noliths and enclaves and in the host rocks were performed. The presenc e of sillimanite-cordierite-biotite-hercynite and of cummingtonite-bio tite-bearing xenoliths suggests that partial melting of a heterogeneou s deep crust played an important role in the genesis of the granitoids . In contrast, the occurrence of microgranular enclaves suggests that a sub-crustal component might have been involved. Two alternative mech anisms are proposed to explain the magma genesis: i) mixing between su bcrustal and crustal melts; ii) direct crustal genesis.