A06_P10

Dating by U-Th and ¹⁴C of secondary carbonate deposits: search for validation criteria. Application to rock art at Nerja cave

Pons-Branchu E¹, Barbarand J², Caffy I³, Dapoigny A¹, Dumoulin J³, Medina-Alcaide M^4,5, Nouet J², Sanchidrian Torti J⁵, Tisnerat-laborde N¹,  Valladas H¹

¹LSCE/IPSL, CEA-CNRS-UVSQ Univ. Paris Saclay, Gif-sur-Yvette, France, ²GEOPS, Univ. Paris Saclay, Orsay, France, ³LMC14, CEA-CNRS-UVSQ Univ. Paris Saclay, Gif-sur-Yvette, France, ⁴PACEA, Univ. de Bordeaux, Pessac, France, ⁵University of Cordoba, Geography and Territory Sciences, Cordoba, Spain, ⁶Instituto Andaluz de Ciencias de la Tierra, Granada, Spain

Accurate dating of cave carbonate parietal samples is a real scientific issue that would have a major impact in prehistory. Decorated Paleolithic caves are abundant and most of them contain wall decorations engraved or traced with metal oxides that cannot be directly dated by carbon 14; their chronology is therefore very uncertain. Many drawings are covered with carbonate deposits that can be dated by radionuclear methods making it possible to open a new field of investigation for research on Paleolithic art.

Since almost 10 years, researches conducted at Nerja cave on these carbonate layers permitted to establish validity criteria. To get meaningful chronological information on the carbonate formation above or below the parietal representation and define validation criteria for dating, we i) characterized the mineralogical structure of the samples to verify that they behaved as a close system and ii) combined ¹⁴C and ²³⁰Th/²³⁴U dating methods on the same sample in order to estimate the reliability of measured ages. We will present a review of previously obtained data and new ones.