Refining the Sarliève palaeolake (France) Neolithic chronology by combining several radiocarbon approaches

Abstract : Dating sedimentary series spanning the past few tens of thousands of years is often problematic due to the quality of 14C data obtained from organic matter (OM), including OM bulk. This question recently arose when establishing the chronology of the sediment infill of the Sarliève palaeolake (French Massif Central). In the studied section of the cores that covers the Neolithic, Ruppia seeds yielded consistent ages for the lower part (7195 ± 75 yr BP to 6050 ± 60 yr BP). The reservoir age of 82 ± 42 14C yr was estimated through the comparison of ages derived from charcoal, Ruppia seeds, and charophyte oogonia sampled on a single level. The upper part of the cores lacks macrofossils and bulk OM dating yields unusable data because of a significant contribution of aged OM derived from the Oligocene substratum in the catchment. We therefore performed datings on lipids extracted from the sediments. The age of lipids was 2880 ± 30 yr BP near the top of the section, i.e. much younger than the age estimated from previous correlations based on pollen assemblages. These new data lead to review previous paleoenvironmental interpretations. The combined dating methodology used for the Neolithic series of Sarliève is a rather uncommon approach that may constitute help to refine chronologies of Holocene sedimentary series.