Studies related to the oceanographic campaigns and sampling (Bibliography) have improved our understanding of this massive volcano revealing that Marsili formed along the spreading center of its basin, acting as a super-inflated ridge.
Detailed bathymetric maps reveal that the volcano stretches 70 km NE-SW, is 30 km wide, and rises 3 km from the seafloor, with its summit 500 meters below sea level (Fig. 1).

Fig. 1. Bathymetric map of Marsili volcano (isobaths 50 m) with sampling locations (modified from Trua et al., 2011)

The volcano’s central axis, about 20 km long and 1 km wide, contains a summit cone with two craters. Smaller volcanic cones are present along its flanks, some 1 km wide and 350 m tall. Curved features along its sides may indicate areas prone to instability. The bathymetric data have also been used to create a 3D model of the volcano (Fig. 2).

Fig. 2. 3D model of Marsili volcano (from Marani et al., 2024)

The sampling of different parts of the volcano yielded a significant amount of volcanic and sedimentary samples. Geochemical and petrological studies on a set of the sampled volcanic rocks provided information on:
magma types and composition. Marsili has predominantly erupted lavas with an IAB (Island Arc Basalt) affinity, with compositions ranging from basalt to andesite (Fig. 3).

Fig. 3. K₂O vs SiO₂ classification diagram for Marsili lavas (from Trua et al 2011)

Geochemical and petrological data suggest a complex sub-volcanic system involving partial mantle melting, interaction with fluids from the subducting Ionian plate, and mantle flow beneath the basin (Fig. 4). This system explains the vertical growth of the volcano.

Fig. 4. Geodynamic framework of the southern Tyrrhenian region (A) and interpretative model (B) (from Trua et al., 2011)

magma pathways and sub-volcanic architecture. Examination of igneous crystals (olivine, pyroxenes, plagioclase) in the lavas provides insight into magmatic processes. The data point to a feeding system beneath the volcano (Fig. 5), similar to the transcrustal plumbing systems seen in other volcanic regions.

Fig. 5. Conceptual model of the Marsili sub-volcanic system, the architecture of which resembles that of a transcrustal plumbing system (from Trua, 2024)

This section of the Tyrrhenian Rocks website is curated by the ISMAR-CNR Research Unit in Bologna (Scientific Coordinator: M. Marani), as part of the PRIN2022-AWARE project (Collaboration network). The ISMAR-CNR Research Unit includes C. Cavozzi and T. Trua (University of Parma) as collaborators. This section will be updated with research results from the units involved in the PRIN2022-AWARE project.

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