Palaeoenvironmental and palaeoclimatic implications of the Late-Quaternary sediment record of Vico volcanic lake (central Italy)



A 15-m-long sediment core recovered from the Lago di Vico caldera lake in central Italy has been the subject of macrofacies description and sedimentological (organic carbon content, grain size and mineralogy) investigation. The results have been integrated with the pollen data from the same core in order to provide a regional climatic and environmental history, with inferences on past lake levels and on moisture and temperature regimes. Radiometric (14C and 40Ar/39Ar) dating, biostratigraphical considerations and tephra analyses provide a chronological framework and indicate that the sequence spans the last 90 000 yr. Several moist periods have been identified that were characterised by enhanced weathering by hydrolysis of the catchment rocks. These alternated with relatively dry phases associated with lowering of lake-levels. The lowest hydrolysis efficiency of the whole record, accompanied by notable aeolian deposition, was attained during the last glacial phase but moisture conditions were such that the lake-level did not decrease, probably owing to reduced temperatures. Evidence for cool climate also emerges for the early Pleniglacial. The highest available moisture was achieved within the Holocene at 5 kyr BP. The Late Holocene does not show either increase of aridity or degradation of the vegetation cover, until at least Roman times. Copyright © 2001 John Wiley & Sons, Ltd.