Preliminary results of combined ESR/U-series dating of fossil teeth from Longgupo cave, China

摘要

Longgupo Cave site, located in Wushan County, Chongqing, China has attracted continuous attention since its discovery of hominid remains in association with late Pliocene-early Pleistocene fauna and numerous lithic artefacts. In 2003-2006, new excavation was carried out on this site, allowing the description of a detailed stratigraphy of the highly complex cave infillings and the sampling of teeth for combined ESR/U-series analyses. Here we report preliminary dating results of seven herbivorous fossil teeth from different archaeological layers of the lowest geological unit (C III). Uranium-series analyses indicate that no obvious uranium leaching has occurred and all the teeth (except one) underwent a very recent uranium uptake history. The obtained US-ESR results show that the age of six teeth are basically consistent, between ～1.4 and 1.8 Ma. At the same time, we observed an inverse correlation of two samples with the stratigraphical sequence. This could be caused by the distinct uranium uptake history of one sample, high uranium content in the enamel for another or bad estimation of external dose rate. Due to the complexity of the stratigraphic sequence, supplementary in situ gamma dose rate measurement should be performed for all the samples during the following excavations in order to confirm this preliminary ESR/U-series chronology.