湖北“郧县人”化石地层的ESR测年研究

ESR DATING ON THE STRATIGRAPHY OF YUNXIAN HOMO ERECTUS,HUBEI,CHINA

本文报道用电子自旋共振法测定与郧县人颅骨同层的９个哺乳动物牙釉质化石年龄的结果。其平均值为５８．１±９．３万年．对被测样检验了其对铀的封闭性，采用指数函数拟合与铀早期加人模型计算年龄．讨论了测年中可能存在的系统误差．

Two almost complete fossil hominid crania(EV900 1 and EV9002) had been early reported to be found in 1989 and 1990 in Middle Pleistocene terrace dePOsit of Han River, Yunxian county, Hubei province, China. They are classified as Homo erectus. In this Paper ten fossil animal teeth stratigraphically associated with the skulls were selected for electron spin resonance (ESR) dating. Since ESR ages depend on the behaviour of uranium in fossils, the closed system assumption was checked for the fossil samples and early uranium uptake model was aPPlied to age determination. Single exPOnent function was used tO fit the ESR intensity response to the irradiation dose and its appropriateness was discussed. The mean age and the standard deviation for these samples are 581 ± 93 ka. It deviates from the geornagnetic dating result of 830-870 Ka. The POssible syStematic errors in ESR dating were discussed and they could not account for the disagreement. Anyway the dating results Place Yunxian craina in between the Homo erectal found at Lantian and Zhoukoudian and indicate that Yunxian crania constitute an important link in the human evolutionary lineage of China.