Refining the Sarliève Paleolake (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 radiocarbon data obtained from organic matter (OM), including bulk OM. This problem recently arose when establishing the chronology of a sediment infill at the Sarliève paleolake (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 to 6050 ± 60 yr BP). A 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 dating of lipids extracted from the sediments. The age of the 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 call into question previous paleoenvironmental interpretations. The combined dating methodology used for the Neolithic series of Sarliève is a rather uncommon approach that may help to refine chronologies of Holocene sedimentary series.

Origin and Holocene geomorphological evolution of the landslide-dammed basin of la Narse de la Sauvetat (Massif Central, France)

“…This prevents a precise use of the produced data (e.g. palynological data) and despite taking into account recent refinement of dates (Hatté et al, 2013).…”

The Palaeoenvironmental Impact of Prehistoric Settlement and Proto-Historic Urbanism: Tracing the Emergence of the Oppidum of Corent, Auvergne, France

“…Only Miras et al [ 16 ] have directly considered long term human impacts, identifying evidence for cereal agriculture from c. 3000–2000 BC, but again this study derived from a mountainous area. Where lowland studies are available [ 22 ], the taphonomic problems mentioned above are prevalent and secure chronologies elusive [ 23 , 24 ]. Thus, despite the existence of a rich history of archaeological and palaeoecological study, the dynamics of human-environment interactions in this part of central France are still poorly understood.…”

Times are changing: A new chronology for Holocene volcanic events and hydro-sedimentary history recorded in the Sarliève marsh (central France)

“…Three chronologies for the sedimentary infilling of the Sarliève basin were published between 2009 and 2013 (see introduction for details): the "Bulk and Ruppia" or BRM model, the "pollen-corrected estimation" -PCE -model (both in Fourmont et al, 2009), and the "lipids model" -LM (Hatté et al, 2013). From its first publication, the BRM appeared aged: the dated materials were mainly carbonated bulk sediment and Ruppia maritima seeds, introducing important and uncontrolled ageing into the age-depth model (Yansa and Long, 2007;Grimm et al, 2009).…”

“…This approach implied several major inconveniences: first, the ages were only estimated; second, the palynozones were extrapolated from mountain areas of the Massif Central, although they are still unclear in the Limagne lowlands; third, it prevented an independent discussion of the chronology of the palynological data. Later works tried to rectify part of the age-depth model (only SU3) by dating lipids (Hatté et al, 2013); however, this led to a significantly younger and controversial chronology that was extremely inconsistent with the regional vegetation history (Miras, 2016). In contrast, the Bayesian age-depth model (BADM) produced in this study is based on carefully selected organic materials for radiocarbon dating, such as charcoal and P r e p r i n t plant/wood remains, and is therefore considered more accurate than the previous models with which it is compared (Fig.…”

“…Unfortunately, the keystone for the integration of these rich multi-proxy studies in the Sarliève marsh (i.e., the radiocarbon chronology of the sedimentary sequence) was highly unsatisfactory because of uncontrolled ageing, and even after several amendments (Hatté et al, 2013), the agedepth model remained controversial due to its inconsistency with the palynological data and regional vegetation history (see Miras, 2016). This situation is especially critical between the Late Neolithic and Antiquity, because different datasets cannot be correlated, preventing any fine discussion on human-environment interactions during late Protohistory, which is considered a crucial period for the consolidation of anthropogenic impacts on natural systems (Berger et al, 2018;Mayoral, 2018).…”