Detrital evaporites and mixed siliciclastic-gypsum arenites are present in the Gessi Formation from the Rossano Basin in Calabria, Italy. The detrital origin of the gypsum fragments in the quartzofeldspathic sandstones is revealed by crystal overgrowths that outline the shape of former gypsum clasts. The gypsum was subsequently transformed into anhydrite at burial conditions. During exhumation, anhydrite was hydrated back to gypsum, a gypsum overgrowth rich in F, Na, K, Cl, and Al formed on the original gypsum grains, and the pore spaces were filled with gypsum cement. Detrital modes of Gessi Formation sandstones suggest complex source-basin relationships in this area during the Messinian salinity crisis. The clastic deposits are the result of deep unroofing of the crustal terranes of the Calabrian arc and the reworking of primary Messinian evaporite facies (selenite). This study indicates that detrital evaporites and mixed siliciclastic-gypsum arenites are more widespread in the Mediterranean area than generally described in the literature.

Plate tectonic history, geological, geochemical (element and isotope ratios), and seismological (P-wave tomography and SKS splitting) data are combined with laboratory modeling to present a three-dimensional reconstruction of the subduction history of the central Mediterranean subduction. We find that the dynamic evolution of the Calabrian slab is characterized by a strong episodicity revealed also by the discrete opening of the Tyrrhenian Sea. The Calabrian slab has been progressively disrupted by means of mechanical and thermal erosion leading to the formation of large windows, both in the southern Tyrrhenian Sea and in the southern Apennines. Windows at lateral slab edges have caused a dramatic reorganization of mantle convection, permitting inflow of subslab mantle material and causing a complicated pattern of magmatism in the Tyrrhenian region, with coexisting K- and Na-alkaline igneous rocks. Rapid, intermittent avalanches of large amounts of lithospheric material at slab edges progressively reduced the lateral length of the Calabrian slab to a narrow (200 km) slab plunging down into the mantle and enhancing the end of the subduction process.

The southern Tyrrhenian region represents a rare case of an active backarc basin where island-arc basalt (IAB)–type and ocean-island basalt (OIB)–type magmas coexist. IAB-type magmatism is the most common, whereas OIB-type magmas are restricted to a few areas. 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.