Early uplift history of the Abruzzi Apennines (central Italy): available geomorphological constraints.

Remants of a flat paleolandscape of erosional origin (top paleolandscape, TPL) have been detected in the Abruzzi Apennines (central Italy) at high elevations (1350–1500m a.s.l.). According to current views, the TPL formation occurred at an elevation close to sea level, and probably marks the first significant geomorphic event in the investigated sector. Since this erosional paleolandscape affects an already deformed pre-Pliocene marine substratum and different structural units, its formation occurred after the thrustfaulting phase, which affected the investigated area. The present elevation of the TPL remnants indicates a significant uplift following the formation of this geomorphic feature. This uplift began during the Pliocene (age of the first post-thrusting continental deposits, subsequent or sub-contemporaneous to the TPL and related to the formation of intermontane basins). Pliocene deposits have been found in the Turano, Salto, and Fucino basins. The origin of these basins was conditioned by the activity of normal faults, which affected and displaced the TPL duringthe Pliocene. Considering (1) that the TPL experienced uplift since the Pliocene and (2) that after the beginning of the uplift phase it was displaced during the Pliocene by the faults responsible for the evolution of the mentioned basins, uplift of the Apennine chain and normal faultingare closely related. The analysis of the mentioned basins permitted to hypothesise a succession of Pliocene–early Pleistocene geomorphic and tectonic events: (1) Pliocene formation of the TPL at low elevation a.s.l.; (2) beginning of the uplift and displacement of the TPL due to the activity of normal faults; (3) formation of the Turano, Salto, and Fucino Pliocene basins; (4) fault activity responsible for the displacement of the Pliocene deposits; (5) erosional phase affectingall the investigated basins; (6) deposition of the Early Pleistocene units.