Interplay between subduction and continental convergence: a three-dimensional dynamic model for the Central Mediterranean

The Mediterranean region is attracting considerable attention due to the complexities of its tectonic setting, which is considered, worldwide, a unique natural laboratory for studying the occurrence of extensional tectonics in a general context of continental convergence. The Tyrrhenian-Apennine system is controlled by the west-dipping subduction of the Pidria-Ionian lithosphere and by the near north-south convergence between the African and Eurasian plates. We provide the first 3-D dynamic model of the Central Mediterranean that quantifies the effects of subduction and convergence on surface deformation, in simplified geometry. The axis of the model extends from Sicily to the Alps along the subduction hinge line. A convergence rate of 1 cm yr(-1) parallel to the subduction hinge has been applied to the Tyrrhenian block, in agreement with global plate-motion models. Density contrasts within the slab cause the gravitational sinking and roll-back of the slab in the southern Tyrrhenian domain. Modelling results show a gradual decrease of hinge retreat from south to north, with values ranging between 8 and 2 mm yr(-1), indicating that the arcuate geometry of the hinge line along the Italian peninsula is ultimately controlled by the interplay between subduction and convergence. The pattern of vertical velocity along directions perpendicular to the hinge, with subsidence in the foredeeps and uplift at the eastern border of the Tyrrhenian domain, is maintained along the whole Italian peninsula, with higher values in the southern areas.