First recovery of marine quaternary deposits from geognostic boreholes of the coastal plain of Marina di Campo (Elba Island: preliminary results)

Here we describe the preliminary results deriving from the analysis of the S2 geognostic borehole, which was drilled near the town of Marina di Campo (Elba Island). Starting from a ground level at 1.29 m above the sea level, 25 m of Quaternary deposits have been cored. These deposits are probably related to the last glacial-eustatic cycle. In particular, the lower part of the borehole is characterized by gravel and sandy-silt sediments typical of a fluvial environment. They settled during a low-stand phase of the Last Glacial Maximum. These deposits are unconformably covered by coastal marine sands, sandy-silts and biocalcarenites (between -11.90 m and -5.20 m from the ground level) that were ascribed to the last sea level rise. The upper part of the geognostic survey is characterized by dark and plastic organic clays (from -5.20 m to the top). The basal clays are still marine (an age of 4.36÷3.81 ky cal BP has been obtained by radiocarbon dating), whereas those of the intermediate part are brackish (3.97÷3.45 ky cal BP). In the upper part we found clays that settled in a freshwater environment.