Relationship between peat bed formation and climate changes during the last glacial in the Venice area

Core and seismic data from the Venice lagoon area, located in the foreland region between the northern Apennines and the southern Alps (northern Italy), allow a detailed investigation of the Late Pleistocene fully continental succession accumulated during the last glacial phase. These deposits consist of an aggrading alluvial plain, some tens of meters thick, which is locally incised by river channels, while both patchy and continuous peat layers complete the succession. In particular, a very continuous peat layer up to 1 m thick (P1), sandwiched within alluvial plain sediments, is well recognizable in the whole lagoon area in both cores and seismic lines. 14C datings of P1 reveal an age ranging between 22 and 24 cal ka B.P., confirming its lateral continuity. All these elements suggest that P1 developed after an episode of marked moisture and large scale cut-off of terrigenous sediment, leading to the establishment of generalized paludal conditions probably during the Laugerie interstadial. As at these latitudes interstadial phases were commonly typified by enhanced arboreal vegetation cover preventing significant terrigenous supply, swamp areas characterized by peat accumulation developed. The present evidence is helpful to recognize stadial-interstadial cycles during the last glacial phase, and may integrate the current knowledge to establish a correlation between cycles recorded in fully continental deposits and those recognizable in ice cores and marine successions.