摘要
本文报告测定骨化石^(231)Pa/^(235)U比值的实验方法,并根据骨化石样品的铀子系法年龄与^(14)C年龄的对比,讨论了铀子系法测定哺乳动物骨化石年龄的可靠性。作者实际测定了华北地区周口店、丁村等十个重要旧石器地点的年代,尝试提出华北地区旧石器文化年表。
The establishment of an absolute time scale for human evolution is of great importance to anthropology and archaeology. Thus the possibility of dating fossilized vertebrate bones by uranium-series method is quite attractive, as 1) fossil bones are frequently associated with paleolithic sites and 2) the time range immediately beyond the 14C limit which spans from 40 thousand years to about 300 thousand years still remains inaccessible to most radiometric techniques.The uranium-series dating is based on the assumption that the post-mortem U-uptake by buried bones is relatively rapid and reaches some saturation level after a time much shorter than the age of bones. Thus the restoration of the equilibrium between U and its daughter nuclei is determined by the decay-growth process only. But this is not always valid. In many cases U migrates continuously in (or out) of the bone after fossili-zation. This leads to the necessity to measure both 230Th age and 231Pa age for every sample, and the concordance between these two ages will be the proof of the validity of the closed-system assumption.This work suggests that if the secondary U-uptake (or loss) is small compared with the U-concentration in fossil bone, the 233Th age and 231Pa/230Th age will serve as the upper and lower limits of the sample’s true age. A complex analysis of several sample dates from one and same archaeological context will improve the accuracy and precision of the age ascribed to the context.An absolute chronological sequence of 10 main paleolithic sites of North China as the results of measurement is listed below:Locality and StratumAge range (103 years}Zhoukoudian Loc. 1 Layer 1?Daili Loc. 78006A Layer 3?Dingcun Loc. 54:100Zhoukoudian New cave Layer 3?Xujiayao Loc. 74093 8 meters beneath earth surfaceQianan ZhuacunSaraosol Stratum of paleolithic culturesShuidonggue Stratum of paleolithic culturesXiaonanhai Layer 6Zhoukoudian Upper cave220?90180?30160?10135?75100?2537?042?032?018?318?3a-spectroscopic technique of ’"Pa/1"!! activity ratio and M
出处
《人类学学报》
1984年第3期259-269,共11页
Acta Anthropologica Sinica
