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 (~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 ~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 on thick crust of the Adriatic interior, the frontal thrust belt and foreland experienced uplift at ~0.5 mm/yr as contraction stepped to deeper structural levels. Uplift of the eastern margin of the extensional hinterland continued at ~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.