Neogenic Evolution of the Mediterranean Region. Geodynamics, Tectonics and Seismicity

The Neogene evolution of the Mediterranean region has been characterized by long migrations of orogenic belts and by the formation of large basins (Balearic, Tyrrhe-nian, Aegean, and Pannonian). The development of crustal extension in a compres-sional context, induced by the convergence of the confining plates (Africa/Nubia, Arabia, and Eurasia), has produced a considerable spreading of opinions about the geodynamics of this region. Some authors suggest the need of assuming additional driving forces with respect to the relative motions of the confining plates. The most cited hypothesis identifies this force in the gravitational sinking of subducted litho-sphere (slab-pull model). Conversely, other authors suggest that the relative motion of the confining plates can explain the tectonic evolution of that region, if the role played by extrusion processes is taken into account. The main object of discus-sions concerns the generation of trench-arc-back-arc systems. Since this consider-able ambiguity may be a major obstacle against the advancing of knowledge on the ongoing tectonic setting and associated seismicity in the Mediterranean region, this book mainly aims at providing the reader with information and arguments that can help to recognize the most plausible explanation of the observed deformation pattern. The proposed geodynamic interpretation suggests that extensional tectonics in compressional contexts can develop in the wake of buoyant structures (mainly orogenic arcs), forced to migrate laterally by the convergence of the confining plates, when the migration rate of the bending/extruding buoyant arcs overcomes the conver-gence rate of the confining plates. The main support to this view is given by the fact that it can provide plausible and coherent physical explanations for the very complex time-space distribution of compressional and extensional tectonic processes in the zones considered. The tectonic evolution of the heterogeneous Adriatic promon-tory, since the Oligocene, suggests that the starting of subduction of old oceanic lithospheric domains (Alpine and Ionian Tethys) was crucially favored by bending/ extrusion of buoyant arcs, driven by plate convergence.