Problems encountered in the U-Th dating of fossil red deer jaws (bone, dentine, enamel) from Lazaret Cave: A comparative study with early chronological data

Previous chronological data such as biochronological data, U-series and ele ctron spin resonance (ESR) data on stalagmitic flowstone E and samples from the sea deposit B are discussed. Most of these early studies show a deposi tion of the archaeological levels C during the oxygen isotopic stage 6. For testing the U-Th dating, the method was applied for the first time to the three tissues (bone, dentine and enamel) from fossil Cervus elaphus jaws in order to date directly the archaeological levels of Lazaret Cave. Twenty-s even bones, 21 dentine and 17 enamel samples from 30 jaws and two tibias ha ve been analysed by alpha spectrometry. The results show a large range of a pparent dates with an open system behaviour. For the majority of samples th e ages range between 50 and 200 ka. The main set of data shows that the age s increase upward in the stratigraphic sequence, with low values near the b ase of the sequence. The U-Th apparent ages of dentine are in better agreem ent with the ages of their respective enamels than with bones. The older th e U-Th ages of the bones the larger the uranium content difference between the bone and dentine samples from the same mandible is observed. For some s amples from all levels of the continental fill, a sequence of episodes of u ranium isotope leaching and accumulation has resulted in increased uranium isotope ratios and modified uranium content yielding anomalous ages. At Laz aret Cave, U-Th dating on bone and dentine was not successful, but data wil l be used for ESR dating.