Reconstruction of the Pleistocene-Holocene Transition in the Venice Lagoon (Italy) Based on High-Resolution Geophysical Survey and Cores

In many coastal areas of the world the Pleistocene-Holocene transition is recorded as the limit between alluvial sediments and marine deposits. In the Venice area, Italy, this transition occurred as a consequence of the marine transgression over a paleoplain after the end of the Last Glaciation. To study the paleogeographical evolution of the Venice area, an extensive geophysical survey was carried out. In its ultrashallow lagoon environments an area of 50 km2 surrounding the historical city of Venice was explored. A detailed analysis of about 900 km of very high acoustic profiles and tens of cores data allowed the recognition of the acoustic signal of the Pleistocene-Holocene transition. This transition is represented by a paleosol now buried by Holocene marine transgressive deposits. It consists of a surface of subaerial exposure locally subjected to river incision and it is locally known as "caranto". For its high compactness the "caranto" provides indirect support to the Venetian building foundations. Thanks to the high spatial resolution of the acoustic data available we could produce a pseudo 3D reconstruction of the "caranto" around the city of Venice.