Late Oligocene to Pliocene extension in the Maltese Islands and implications for geodynamics of the Pantelleria Rift and Pelagian Platform

The tectonic and geodynamic evolution of the Pelagian platform and of the Pantelleria Rift System, located in the foreland of the Apennine-Sicilian-Maghrebian Belt, from the Late Oligocene onward, is still debated. Here we present a new interpretation based on structural data collected in the Malta and Gozo islands. With a tectonic back-stripping approach, we recognized two main extensional events separated by a period of tectonic quiescence: (D1) Early Miocene WNW-ESE extension and (D2) Late Miocene to Pliocene N-S extension that led to the opening of the Pantelleria Rift System. During both extensional events the Maltese Islands and the Pelagian Platform were located in the foreland of the Apennine-Sicilian-Maghrebian Belt (Western Mediterranean Arc), in a period of slab rollback. We suggest that both tectonic events are an evidence of the extensional regime imposed on the foreland area by the rollback of the subducting slab. The switch in the main extension axis between D1 and D2 (WNW-ESE vs. N-S) can be interpreted as a result of the varying orientation and distance of the trench due to the progressive development of the Western Mediterranean Arc and provides an independent tool to "monitor" the slab rollback. Results obtained in this study allowed, for the first time, to bind the tectonic evolution of the area with the geodynamic evolution of the Western and Central Mediterranean.