When were the walls of the Chauvet-Pont d'Arc Cave heated? A chronological approach by thermoluminescence

•TL dating was undertaken on heated limestone fragments from walls at the Chauvet cave.•A novel SAR-like protocol of equivalent dose measurement was implemented.•High level of radon in the cave and large excess of 210Pb in samples were observed.•A model accounting for the closure of the cave was used for annual dose determination.•The TL dates (37–34 [±3] ka) agree with the calibrated 14C dates of first occupations.

Direct chronological data of the ancient heating of calcitic walls at the Chauvet-Pont d'Arc Cave (Ardèche, France) were obtained at the Galerie des Mégacéros and at the Eboulis d'Entrée. Fragments of reddened limestone were extracted from the walls and were studied by thermoluminescence (TL). A novel measurement protocol of the equivalent dose (ED) was implemented and was optimized with respect to the nature of the material being dated (calcite), to the small quantities of sample available and to the relatively low heating of the rock surface in the past (close to 350 °C). The presence of a high level of free radon in the cave and 210Pb in large excess in samples implied the development of a specific irradiation model allowing the evaluation of the mean annual dose over time, taking into account possible scenarios of radon and daughters migration from the bedrock. The following dating results were obtained (in ka before the present and associated total estimated standard deviation):- Galerie des Mégacéros, 36.9 ± 2.3 ka.- Eboulis d'Entrée, 34.3 ± 2.9 ka.These data are in agreement with the calibrated radiocarbon dates of the most ancient periods of human occupation in their respective areas. TL dates indicate that the fires which altered the walls were lighted during the first paleolithic human occupation period. Eventually, TL dating of the heated surface of the bedrock opens a new window on the chronology of human activities in the Chauvet-Pont d'Arc Cave and it makes an alternative contribution to the demonstration of the early chronology of its rock art.