The earliest evidence of hominid settlement in China: Combined electron spin resonance and uranium series (ESR/U-series) dating of mammalian fossil teeth from Longgupo cave

摘要

Longgupo cave, located in Chongqing Municipality, China, was discovered in 1984. Sixteen Gigantopithecus teeth and two hominid fossils accompanied with abundant mammalian fossils and stone artifacts were unearthed from the site. Previous dating result is questioned because of the complexity of deposition history. In this study, seventeen mammalian fossil teeth collected from different layers of unit C II and C III (C III') during the 2003-2006 Sino-Franco joint excavation were analyzed by combined ESR and U-series methods, and calculated with a US-ESR model. In situ dose rates were remeasured in detail in 2012, in order to refine the external dose rate determination. Uranium-series analyses indicate that no obvious uranium leaching has occurred, and all the teeth underwent a very recent uranium uptake history, except one from layer C III 3 of the south wall. The US-ESR results show that the ages of ten teeth from unit C III' of the north wall are consistent in general, about 2.35 Ma. The ages of seven samples from south wall are not in accordance with the stratigraphic order: three teeth are much younger than the other four, probably attributed to the relative higher uranium concentration and U/Th ratio in the dental tissues and significant higher in situ gamma dose rate. Nevertheless, the three teeth from C III of the south wall give an average age of - 2.48 Ma. The fossil ages obtained in this work combined with paleontological evidence and new paleomagnetic results place Longgupo at the very beginning of the Early Pleistocene. Compared with other early hominid settlements, Longgupo is one of the earliest evidences of hominid settlement in China and East Asia to date. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.