Previous and new data on the main granitic intrusions emplaced in the Northern Tyrrhenian Sea an Southern Tuscany during Mio-Pliocene are critically examined with the aim of characterizing their geochemical features, and revaluating their genesis. Two main groups have been distinguishe: the Elba group, which also includes the Campiglia and Larderello intrusions, and the Giglio group, which also includes the Gavorrano intrusion. The Montecristo pluton exhibits features common to both the Giglio and Elba groups. Most of the Gavorrano and Campiglia rock samples have suffered hydrothermal alteration inhibiting a reliable petrogenetic study. The occurrence of rounded mafic enclaves in these granitoids, believed to represent blobs of disrupted basic magma, is very relevant with regard to the genesis of the Tuscan Magmatic Province intrusive rocks. In fact, a quite complex Mixing plus Fractional Crystallization (MFC) process between a crustal peraluminous magma and a mantle-derived magma(s) of potassic affinity is suggested on the basis of petrochemical and isotopic data. Deep crustal metapelites of composition similar to the garnet-bearing micaschist rocks belonging to the Tuscan Paleozoic basement probably represent the crustal source of the peraluminous magmas, whereas the basic end member(s) could have geochemical characteristics similar to the subcrustal magmatism of potassic affinity which occurred in the Northern Tyrrhenian Sea and Tuscan y during Mio-Pliocene.
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