Contribution of coupled ESR/U-series fossil dating to a Paleolithic-Neolithic transition site - Naminan, Southwest China

The coupled ESR and U-series (ESR/U-series) method has been increasingly utilized for dating fossil teeth from Early to Middle Pleistocene hominid sites. One significant advantage of this method is its ability to directly analyze fossil animal or human teeth. However, compared with other radiometric methods such as 14C charcoal dating, U-series carbonate dating, and OSL sediment dating, this dating method is rarely employed for Late Pleistocene or younger sites. In this study, we present an ESR/U-series dating investigation conducted at the Naminan site, a Paleolithic-Neolithic transition (P-N transition) site situated on the Sino-Myanmar border. The ESR/U-series analysis of eleven dental samples yields an age range of 18.1-13.2 ka for the fossils. These obtained ages are generally consistent with the 14C chronology of the site. When dealing with young fossil samples, it was observed that due to relatively low uranium concentration in dental tissues, internal dose rate plays a less significant role compared to external beta and gamma dose rates in the total dose rate of the fossil samples. Consequently, evaluating the dose rate of surrounding sediment becomes a primary source of uncertainty. Additionally, in this study we attempted to employ the standardized growth curve (SGC) and representative dose response curve method for determining Equivalent Dose (DE), which was then compared with values obtained using additive dose method (ADM). Although the precision of DE estimated by two methods are comparatively lower than that of ADM, it demonstrates the potential to efficiently determine a more rational Dmax for irradiation, identify samples with stratigraphic disturbances, and analyze small or valuable fossil specimens.