Lower crustal granite genesis connected with chemical fractionation in the continental crust of Calabria (southern Italy)

Granulite-facies rocks, of metasedimentary and metaigneous type are exposed in the Serre (Southern Calabria). They are representative of the intermediate - lower crust remaining after the Hercynian orogeny and exhumed during the Alpine orogeny. In this paper, we deal with the composition of the lower crust and its relationship with granitoids along the Serre section. The metapelites, which make up a large part of the lower crust section, have a restite character due to the extraction both of in situ crystallized leucosomes and of some of the late-Hercynian peraluminous granites which intrude the upper crust. The dominant calc-alkaline granitoids seem to require the contribution of hydrated basic lower crust and/or mantle-derived magmas for their genesis. As a result it appears that the melting processes which affected the lower crust about 300 Ma ago produced a crustal differentiation contributing to the generation of granitoids which migrated toward high crustal levels. The occurrence of some gabbroic rocks and microgranular mafic enclaves associated with the calc-alkaline plutonic rocks indicates that the mantle contributed both thermally and chemically to granitoid genesis. -from Authors