A new multi-method approach for dating cave calcite: application to the cave of the Trou du Renard (Soyons, France)

Abstract. A multi-method approach aimed at characterizing carbonate parietal deposits and at proposing a chronology for these carbonate crusts is described. Dating was performed by radiometric methods (C-14 for recent samples, and U-series) on samples that had been characterized beforehand using optical and cathodoluminescence microscopy, and Fourier Transform Infrared microspectroscopy. For U-series, high precision on U-Th ages was achieved using liquid phase multicollector-ICP-MS applied to large samples, while laser-ablation single collector - ICP-SFMS provided information on the reliability of the sampling with a high spatial resolution. This methodology, based on the combination of these two techniques reinforced by the information obtained by the calcite characterization methods, was applied to carbonate deposits from the cave of the Trou du Renard (Soyons, France). The ages obtained with the two U-Th dating techniques are comparable and illustrate that different laminae were deposited at different rates in the samples. In the future, this procedure based on the mineralogical and geochemical characterization of the samples and their dating by radiometric methods will be applied to the layers of parietal carbonates deposited on Palaeolithic decorated walls. When the crystallization is slow, the U/Th dating method by imaging technique is of interest as well as that by multicollector-ICP-MS in liquid phase. The development of robust dating methods on very small quantities of material will make it possible to define the chronological framework of cave rock art.