Integrated approach of sedimentary processes on paleosol and calcareous tufas in two Late Quaternary sequences in Mediterranean contexts (Southern France)

Abstract

In southeastern France, the Upper Palaeolithic, Mesolithic and Early Neolithic periods are poorly represented in open-air archaeological sites. Among all the potential factors (e.g., climatic impacts, cultural practices, lack of surveys) what part do geomorphological processes play on conservation and/or destruction of open/air sites? To answer this question, this study proposes an integrated approach to analyze geomorphological processes and their taphonomic impacts on the presence/absence of archaeological sites or remains. It is based on the study of regional sedimentary markers of temperate phases with high archaeological and palaeoecological preservation potentials: detrital paleosol formations and calcareous tufas formations. The methodology links their elemental (pXRF), granulometric and colorimetric compositions to sedimentary dynamics, temporalities and depositional modalities on two sequences of South-East France. In the Upper Palaeolithic, the presence of pedologic horizons in cryoclastic glacis marks phases of environmental stability with low sedimentation rates, temperate climate, forest cover. However, these horizons record detritism and erosion of the watershed. The archaeological gaps are therefore potentially attributable to disturbances of a climato- morphogenic nature that would have altered the state of conservation of potential remains. In the transition between Mesolithic/ Early Neolithic and the Bronze Age, the analysis of tufas sequences, formations rich in bioindicators sensitive to disturbances of their biotope, show that the archaeological gaps are linked to a weak anthropic influence on the environment. The lime mud phases with poorly constructed and low detrital facies indicate stable periods, the first punctual and localized disturbances (watershed) are only recorded from the Neolithic onwards with the increase in detritism and reworked elements.