GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.3 - POSTER GNGTS 2023 Is the Africa-Eurasia convergent margin in western Mediterranean re-organizating? M. Palano 1 , A. Billi 2 , M. Cuffaro 2 , B. Orecchio 3 , D. Presti 3 , C. Totaro 3 1 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania - Osservatorio Etneo, Catania, Italy 2 Consiglio Nazionale delle Ricerche, IGAG, Roma, Italy 3 Department of Mathematics, Computer Sciences, Physics, and Earth Sciences, University of Messina, Messina, Italy In the western Mediterranean, following the substantial consumption of the Tethyan ocean and the intervening continent-continent collision, the pristine subduction has progressively (at least, since about mid-Miocene time) come to an end or almost in large sectors and compressional deformation connected with the ongoing Africa-Eurasia convergence has progressively resumed (since about 8 Ma) to the southern passive margins of the Tyrrhenian, Liguro-Provençal, Algerian, and Alboran back-arc basins. In these areas, the comprehension of future tectonic processes between the converging plates passes through the identification of new or future plate margin segments and related deformation processes. To do so, a database of recent and earthquake, GNSS data and tectonic data has been compiled and spatially analyzed between Calabria and Gibraltar. Although it must be considered at an immature stage, based on these data we drawn and kinematically defined the nascent plate boundary. It is formed by variably oriented inherited structures and is characterized by a discrepancy between the general motion of Africa with respect to Eurasia and the local contractional/compressive axes deduced from geodetic and seismic data. The oblique convergence along the nascent boundary matches that recorded in other instances of subduction initiation elsewhere; however, the average convergence rate ( ∼ 5mm/yr) in the Mediterranean seems currently too small for such a subduction initiation. Based on the assumption of a future northward tectonic vergence (i.e., Eurasian foreland), the Tyrrhenian, Algerian, and Betic salients, the Oran and Fès recesses, and the Ionian, Trans-Alboran, and Gibraltar transfer zones are identified along the nascent boundary. The future of the western Mediterranean suture zone cannot be confidently envisaged, but its geological complexity surely makes this area an optimal laboratory to unravel the development of ancient suture zones that may comprehend inverted back-arc basins, along-strike variations of tectonic regimes, doubly-vergent subductions and fold-thrust belts, transverse continental blocks, and arched structures.