A buried volcano in the Calabrian Arc (Italy) revealed by high-resolution aeromagnetic data

A high resolution aeromagnetic campaign carried out by the National Institute of Geophysics and Volcanology of Roma (INGV) between the Aeolian Archipelago and the Westernmost side of the Calabria arc (Southern Tyrrhenian Sea, Italy) reveals the presence of an unrecognized up to now volcano 15 Km westward from the Tropea village shorelines. Aeromagnetic data show a WNW-ESE elongated positive magnetic anomaly centered on the Capo Vaticano morphological ridge (Tyrrhenian coast of Calabria), which is characterized by an apical, sub-circular, flat surface. Forward and inverse magnetic modeling show a 20 km long and 3-5 km wide magnetized body that extends from sea floor to about 3 km of depth. The magnetic properties of such a body are consistent with those of the medium to highly evolved volcanic rocks of the Aeolian Arc, i.e. dacites and rhyolites. In the Calabria mainland, widespread, dacitic to rhyolitic pumices with calc-alkaline affinity of Pleistocene age (1-0.7 Ma) are exposed. The tephra falls are related to explosive activity and show thickness decreasing from the Capo Vaticano area southeastward. The presence and dimension of the lithics indicates a provenance from a source located not far from Capo Vaticano. The combined interpretation of the magnetic and available geological data reveal that: (a) the Capo Vaticano WNW-ESE elongated positive magnetic anomaly is due to the occurrence of a WNW-ESE elongated sill, (b) such sill represents the remnant of the plumbing system of a Pleistocene volcano that erupted explosively producing the pumice tephra exposed in Calabria, (c) the volcanism is consistent, in terms of age, magnetic signature, and geochemical affinity of the erupted products, with the Aeolian products. The results indicate that such volcanism developed along seismically active faults transversal to the general trend of the Aeolian Arc and Calabria block, in an area where uplift is maximized (ca. 4 mm/yr). Such uplift could be also responsible for the fragmentation of the upper crust and the formation of transversal faults along which seismic activity and volcanism occurs.