Occurrence of several explosive eruptions from Marsili seamount: new geochemical data of the Marsili volcanic activity during the last 6.7 ka B.P.

The Marsili oceanic-like basin (Southern Tyrrhenian Sea, Italy) is an about 2 Ma old back-arc related to the north-westward subduction of the Ionian lithosphere below the Calabrian Arc (Ventura et al., 2013 and reference therein). Several studies focused on the geodynamic interpretation of that area, which is characterized by coexisting active volcanism, compressive and extensional deformations and slab rollback processes. The evolution of the Marsili Seamount (MS), which is located in the central sector the back-arc basin, is still debated. MS is one of the largest volcano of Mediterranean Area and Europe, measuring about 70 km in length and 30 km in width with the top at ~500 m b.s.l.. The about 1 to 0.03 Ma fissural and central MS activity form a complex segmented volcanic structure (Ventura et al., 2013). Effusions of lava flow represent the main eruptive style along with minor explosive eruptions that produced fall and flow deposits in historical time (Iezzi et al., 2014). The composition of the products ranges from medium-K calcalkaline basalts to high-K calcalkaline andesites related to both IAB and OIB-like mantle sources (Trua et al., 2011). In this contribution, we present new stratigraphic and geochemical data, as well as AMS 14C dating from a 2.35 cm deep-sea gravity core "Marsili1" recovered at 940 m b.s.l. in the MS central area. In particular, major and trace element glass composition (EMPA and LA-ICP-MS) of five tephra layers recovered along the core are reported. The geochemical features of the tephra layers allow in identifying MS and Mt. Etna as source areas. On the base of AMS 14C dating, the MS tephras emplaced between 2 and 7 ka B.P., whereas the Etna distal layer can be correlated with the Y-1 marker layer (ca. 17 ka B.P.). Our results testify, within the recent MS activity, recurrent explosive eruptions in historical time. The occurrence of submarine explosive eruptions in the last 7 ka implies an evaluation of the potential hazards.