Paleoenvironmental features of a peri-euganean (Padua, northern Italy) depression during the late Quaternary: first results

Abstract

We report the first results of a multidisciplinary research addressed to reconstruct the paleoenvironmental evolution of a sedimentary basin, from the SE sector of the Colli Euganei area (Padua, Northern Italy). It is likely that the sedimentation in the basin was active at least over the time span from the Wormian glacia-tion up to the end of Pleistocene. The site is interesting because it was scarcely subjected to flooding by the nearby Adige and Brenta rivers. As a result the basin was almost continuously subjected to low energy conditions consistent with significantly long lasting episodes of peat accumulation. A 50 m long continuous core drilled at nearly the center of the basin provided a sediment record consisting of clay, silt and sands layers along with recurrently interbedded peaty levels of variable thickness. Radiocarbon dating of peat from 3.3, 18.6 and 33.0 m deep in core yielded the ages of 19,000, 25,900 and > 43,000 yr BP, respectively, thus providing evidence that if the topmost portion of the sequence did not undergo natural erosion or exploitation of peaty levels, the basin ceased to be active far before Holocene. Results of the pollen analysis so far performed, relative to the 2.4 and 3.3 m deep levels, agree in ruling out the occurence of the Quercetum-Carpinetum boreoitalicum forest. In particular, at 2.4 m deep the identified NAP taxa, almost equally the AP, suggest the occurence of dry steppe climate. By reverse downcore, at 3.4 m deep it has been found that NAP greatly prevails over AP and, further, the higro/hidrophylous plants became dominant, thus likely reflecting a phase of climatic deterioration. The sediment suite also provided some remnants of Coleoptera: Their identification, however is still in progress.