Magmatism Along Lateral Slab Edges: Insights From the Diamante-Enotrio-Ovidio Volcanic-Intrusive Complex (Southern Tyrrhenian Sea)

Volcanic-intrusive complexes often formed along lateral slab edges as a consequence of subduction-induced mantle flow. We investigate this process in the southern Tyrrhenian Sea by integrating multibeam bathymetry, seismic-reflection data, regional magnetic anomalies data, and seismological data. The interpretation of the data highlights the presence of magmatic intrusions that locally reach the seafloor forming volcanic edifices. Chimneys, lava flows, and laccoliths are observed beneath and surrounding the volcanoes. The emplacement and cooling of the magma occurred during the Brunhes Chron. The volcanoes are not active even if the hydrothermal activity occurs. The volcanic-intrusive complex can be subdivided in a western domain (Diamante and Enotrio seamounts) where strike-slip transpressional faults deform the volcanic edifices and an eastern domain (Ovidio volcanic seamounts) characterized by flat-topped volcanic edifices. The flat-topped morphology is the result of the interplay between volcanism, erosion, sedimentation, and sea-level change. The Ovidio volcanic seamounts formed in an area that experienced at least 60 m of subsidence. Magnetic signatures over the northern side of the Ovidio and Diamante seamounts highlight the presence of a deep-rooted, magnetized feeding system remnant. Volcanic edifices extend above a magma feeding system, characterized by low Vp/Vs ratios. The Diamante-Enotrio-Ovidio volcanic-intrusive complex formed as a consequence of the ascent of subduction-induced mantle flow originated in the northern-western edge of the retreating Ionian slab. We speculate that the magma ascent was controlled by a strike-slip deformation belt, which accommodated the bulk of the shear strain resulting from the formation of a roughly E-W trending, Subduction-Transform Edges Propagator fault.