Geochemical features and geodynamic significance of the southern Tyrrhenian backarc basin

Geochemical and isotopic characteristics of southern Tyrrhenian submarine volcanic samples are summarized herein, with special attention to samples recovered during recent seafloor sampling. Samples derived from Marsili volcano, the biggest seamount in the Tyrrhenian Sea, together with those of the Prometeo submarine lava field and Palinuro seamount, give a comprehensive picture of the mantle sources of southern Tyrrhenian magmatism. Most of these samples are relatively high-magnesian basalts that approximate primary magma compositions, thus providing insight into petrogenesis of IAB- and OIB-type magmas of this area. Petrological data, integrated with new bathymetric data, allow the geodynamic evolution of the southern Tyrrhenian backarc basin to be reconstructed. We suggest that the transition from IAB- to OIB-type magmas recorded in the southern Tyrrhenian backarc basin is related to the propagation of asthenospheric mantle from beneath Africa around the edges of the Ionian slab. The data suggest that the inflow of asthenosphere from beneath Africa has been important since the early Neogene evolution of the southern Tyrrhenian region.