Subduction or delamination beneath the Apennines? Evidence from regional tomography

Abstract

In this study we present a new regional tomography model of the upper mantle beneath Italy and the surrounding area derived from the inversion of travel times of P and S waves from the updated International Seismological Centre (ISC) catalogue. Beneath Italy, we identify a high-velocity anomaly which has the appearance of a long, narrow "sausage" with a steeply dipping part down to a depth of 400 km and then expanding horizontally over approximately 400 km. Rather than to interpret it as a remnant of the former Tethyan oceanic slab, we consider that it is made up of the infra continental lithospheric mantle of Adria, which is progressively delaminated, whereas its overlying crust becomes progressively accreted into the Apenninic tectonic wedge.