Late Pleistocene sedimentation in the foreland of South-Eastern Alps

The glacial expansions occurred in the South-Eastern Alps during LGM and previous glaciations largely deleted the sedimentary record existing in the main valleys, limiting the possibility to reconstruct the Quaternary history of the mountain catchments. But some major constraints about timing and magnitude of phases involved in the evolution of the South-Eastern Alps could be supported by the analyses of the infilling of their foreland, which corresponds to the Venetian-Friulian Plain. The presence of the Adriatic Sea during the interglacial phases allows also to link marine and glacial sedimentary record, which is not possible along the other sides of the Alps. In the last decade, large geological, geomorphological and pedological mapping projects have been investigating the Venetian-Friulian Plain, strongly improving the available information about Late Pleistocene sedimentary processes. This research presents an overview of the evolution of the alluvial and coastal plain since the end of Middle Pleistocene to the Lateglacial. This was mainly possible through detailed field surveys and 20 stratigraphic cores 50–270 m-long. A strong relation between alluvial aggrading phases and glacial periods (final part of MIS 6 and LGM) is evidenced, whereas during the last interglacial the sedimentation mainly occurred in the coastal sectors. During the Tyrrhenian transgression (MIS 5e) the lagoons reached a more landward position than the present. The deposits of Middle Würm are represented by thin alluvial sequences and an important depositional hiatus lasted tens of thousand of years ended around 35-30 ka cal BP. The LGM is characterized by a strong phase of deposition until 20 ka cal BP, then the sedimentary rate lowered and in the Friulian Plain led to apical incision of alluvial systems. Since the Lateglacial an important erosive phase affected the whole plain and brought to the formation of deep and wide incision up to the present coast.