Rates of late neogene deformation along the southwestern margin of Adria, Southern Apennines orogen, Italy

During latest Miocene to Early Pleistocene deformation of the southwestern margin of Adria, the frontal thrust of the Southern Apennines orogen migrated toward the foreland rapidly (similar to 16 mm/yr) and was accompanied by subsidence with the frontal thrust belt and foredeep remaining at or below sea level. In contrast, the orogenic hinterland experienced extension, which was accompanied by uplift at similar to 0.3 mm/yr along the eastern transition to the contractional belt but net subsidence and formation of the Tyrrhenian basin farther west. Through time, the extensional belt progressively widened toward the northeast at the same rate as the encroachment of the thrust front on the Adriatic foreland. Following a mid-Pleistocene reduction in horizontal displacement rate associated with impingement of the thrust belt oil thick crust of the Adriatic interior, the frontal thrust belt and foreland experienced uplift at similar to 0.5 mm/yr as contraction stepped to deeper structural levels. Uplift of the eastern margin of the extensional hinterland continued at similar to 0.3 mm/yr and is followed by tectonic Subsidence along the Tyrrhenian coast of southern Italy. Today, the pattern of mid-Pleistocene displacements continues, as suggested by seismicity and GPS velocities. The similarity in migration rates of contractional and extensional fronts across southern Italy over the last 6 million years supports models of crustal delamination and roll-back of the subducted Adriatic slab as a fundamental driving mechanism for deformation along the western margin of Adria. Temporal variations in the vertical and horizontal rates of deformation, however, probably reflect differences in crustal structure and are not directly related to lithospheric processes. The reduction in the horizontal displacement rate associated with the onset of rapid foreland and frontal thrust belt uplift during the Early Pleistocene corresponds to a change from thin- to thick-skinned contraction initiated with the involvement of thick continental crust in regional shortening. Thin continental Crust promoted thin-skinned contraction accompanied by Subsidence, whereas thicker continental crust resulted in thick-skinned shortening and uplift.