第四纪骨化石样品的多方法对比测年

COMPARATIVE STUPY OF QUATERNARY FOSSIL BONE DATING

本文报道作者用^(14)C、铀系和ESR等多种测年技术对比测定第四纪骨化石样品年龄结果,对比分析骨化石中各含碳组分^(14)C年龄的异同。在此基础上讨论诸测年方法的可靠性和测年精度,分析哪种含碳组分最能代表骨质样品的真实年龄。对晚于40 000aB.P.的骨质样品,作者倾向于样品中氨基酸的^(14)C测年,而对更老的样品,铀系法应优先被选用。本文还对北京周口店山顶洞遗址骨化石样品中不同含碳组分的^(14)C测年结果做了讨论。

Fossil bones constitute one important category of dating objects for Quaternary study, because they are frequently found in Quaternary sediments and serve as indicators of relative chronology and palaeoenvironments. Various Quaternary dating techniques have been applied to this kind of material with varying degrees of success. This paper summarizes the current status of bone dating, as welt as our own researchachievement in this field with the purpose of showing the reliability and precision which each dating technique is able to achieve and the influencing factors in dating. The author prefers radiocarbon dating, of amino-acid fraction for younger bones, because contamination with mobile humic acid may sometimes cause the apparent age to appear lower than it actually is. Experiments with a fairly large number of samples definitely showed that U-series ages of fossil bones, if they can be proved to be of closed systems, are close or equal to the radiocarbon ages of the same samples or samples from the same archaeological context. Therefore U-series dating is a promising dating technique for bone samples older than 40 000aB.P. The electron spin resonance (ESR) dating was shown unsuccessful in our experiments with fossil bones and dentine; the ESR ages were consistently too low. The factors accountifig for the failure, were discussed and teeth enamel was suggested as a more reliable candidate for ESR dating. The problems in amino-acid racemization dating of fossil bones were touched on in this paper also. The age of the Late Palaeoiithic Culture of Upper Cave, Zhoukoudian, Beijing is discussed on the basis of newly published bone datingresults with the AMS technique.