$^{40}$Ar/$^{39}$Ar and ESR/U-series dates for Guado San Nicola, Middle Pleistocene key site at the Lower/Middle Palaeolithic transition in Italy

International audienceThe Middle Pleistocene archaeological site of Guado San Nicola was discovered in 2005 in a fossil fluvial terrace of the Volturno River, close to the village of Monteroduni, Molise, Italy. Palaeontological remains and lithic artefacts, including both handaxes and Levallois, discoid and opportunistic debitage, were recovered in fluvial and slope sediments rich in volcanoclastic materials. This site includes four distinct human occupation levels. In two of them both "shaping-faconnage" and "knapping-debitage" technologies are highlighted, placing this site at the Lower/Middle Palaeolithic transition. In the present study, geochronological analyses by Ar-$^{40}$/$^{39}$Ar on single-crystal and ESR/U-series on teeth were performed to precise the chronological framework of the occupations. The $^{40}$Ar/$^{39}$Ar data obtained securely bracket the human occupation levels at the transition between the interglacial and glacial marine isotopic stages MIS 11 (i.e. 400 $\pm$ 9 ka) and MIS 10 (i.e. 345 $\pm$ 91 ka). The weighted mean age obtained from ESR/U-series dating of six teeth (i.e. 364 $\pm$ 36 ka) is in very good agreement with the $^{40}$Ar/$^{39}$Ar results. The radio-isotopic constraints we presented place the Guado San Nicola site as one of the earliest testimonies of Levallois debitage in Western Europe and confirm the potential and accuracy of paleo-dosimetric methods to date Middle Pleistocene sites