The Southern Tyrrhenian magmatism is characterized by the close association of alkaline and calc-alkaline products (Figures 1 and 2). Quaternary sodic alkaline basalts crop out at Pantelleria, Linosa and Ustica island, Etna, Iblei, Prometeo and Vulture (Figure 1). These volcanic suites are geochemically and isotopically akin to OIB [e.g., Cinque et al., 1988; Civetta et al., 1998; Beccaluva et al., 1998, 2002; Gasperini et al., 2002; Trua et al., 2003]. Calc-alkaline volcanic activity is represented by the Aeolian arc and other Tyrrhenian seamounts [e.g., Francalanci et al., 1993; Savelli, 2002]. The magmatism of the Neapolitan volcanoes (Campi Flegrei, Ischia, Procida, Vesuvius) has been also genetically related to the subduction process [e.g., Beccaluva et al., 1991; Tonarini et al., 2004].
 To evaluate the mantle composition (i.e., orogenic versus anorogenic), we utilized some geochemical and isotopic tracers (87Sr/86Sr; Ba/Nb) from the volcanic products erupted during the last 800 ka. The data is plotted along a section (Figure 5), incorporating from SW to NE: Pantelleria, Ustica, Prometeo, Aeolian islands (divided in three groups: Alicudi; Filicudi, Salina, Vulcano, Lipari, Panarea; Stromboli), Procida, Ischia, Campi Flegrei, Vesuvius, Vulture. We also projected on the profile data concerning Etna and the Tyrrhenian Sea MORB (Marsili, active during the last 2 Ma). To take into account the effects of fractionation, we filtered the chemical data to include rocks with MgO > 5 wt. For each volcano, we reported the lowest measured Sr-isotopic ratio and the average Ba/Nb ratio, to minimize effects of contamination and fractionation. The latter element/element ratio was chosen because arcs are characterized by high LILE/HFSE ratios, distinct from the trace element distribution of anorogenic magmas. The consensus is that this enrichment is a reflection of fluid/melt controlled partitioning of LILE relative to HFSE from the slab to the mantle wedge. The geochemical data are presented with the corresponding tomographic section, showing the along strike prospective of the narrow Calabrian slab. The Aeolian arc and the Neapolitan volcanoes are characterized by high Ba/Nb ratios, with respect to the Pantelleria, Ustica and Tyrrhenian Sea basalts, which are considered to be the most akin to the African asthenospheric mantle [D'Antonio et al., 1996; Civetta et al., 1998]. Prometeo and Etna are characterized by slightly higher Ba/Nb ratios. Vulture has a Ba/Nb ratio higher than those of the Pantelleria, Ustica and Tyrrhenian Sea basalts, but lower than those of the Aeolian Islands and of the Neapolitan volcanoes. The Sr-isotope ratio progressively increases from Pantelleria to the Neapolitan volcanoes; low value is found in the Tyrrhenian Sea basalts. The Vulture rocks display an isotopic composition less radiogenic than the Neapolitan volcanoes but significantly higher than the other volcanoes. Nd- and Pb-isotope ratios (data not shown) display similar relationships but with a reversed trend. Both Ba/Nb and Sr-isotope ratios patterns show rather distinct features that can be correlated with the distribution of velocity anomalies: low isotopic ratio in the Sicily channel region is placed on top of a low velocity anomaly, whereas the Aeolian Island high isotopic ratio is placed on top of a high velocity anomaly, the Calabrian slab. The Neapolitan area isotopic ratio instead is placed on top of the low-velocity anomaly below the Southern Apennines.