Coupling basin infill history and mammal biochronology in a Pleistocene intramontane basin: The case of western L' Aquila Basin (central Apennines, Italy).

The western L'Aquila Basin recorded in Quaternary times two well distinguished phases of intramontane basin fill, concomitant with uplift of Central Apennines and characterized by diverse Large Mammal assemblages. The first phase was dominated by alluvial fan and lacustrine-palustrine sedimentation, respectively Gelasian and Calabrian in age, that took place within an internally-drained, fault controlled, hydrographic system. A late Villafranchian-earliest Galerian Large Mammal assemblage, approximately 1.3e1.1 Ma, pertains to this phase and includes: Mammuthus meridionalis, Stephanorhinus etruscus and the large cervid Arvernoceros aff. A. giulii. The second phase of filling, Middle Pleistocene to Holocene in age, is dominated by fluvial sedimentation, which is related to a through-going fluvial system developed after the emptying of the former lake. A middle Galerian Large Mammal assemblage, approximately 600 ka, comes from the oldest deposits of this phase. Biochronological data help date steps of geological and morphological evolution in an intramontane setting, and permit to temporally constrain the major change in local hydrography and sedimentation at the Early-Middle Pleistocene transition. This change was likely forced by an increment of uplift rates, which is well recorded along the axial range and peripheral belts of the Apennines.