Calculations, according to some open-system models, point out that while a statistically significant discrepancy between the results of two U-series methods, 230Th/234U and 227Th/230Th (or 231Pa/235U), attests a relat...Calculations, according to some open-system models, point out that while a statistically significant discrepancy between the results of two U-series methods, 230Th/234U and 227Th/230Th (or 231Pa/235U), attests a relatively recent and important uranium migration,concordant dates cannot guarantee closed-system behavior of a sample. The results of 20 fossil bones from 10 Chinese sites, 19 of which are determined by two U-series methods, are given.Judging from independent age controls, 8 out of the 11 concordant age sets are unacceptable.The results in this paper suggest that uranium may cycle into or out of fossil bones, such geochemical events may take place at any time and no known preserving condition may securely protect them from being affected. So for the sites we have studied, the U-series dating of fossil bones is of limited reliability.展开更多
文摘Calculations, according to some open-system models, point out that while a statistically significant discrepancy between the results of two U-series methods, 230Th/234U and 227Th/230Th (or 231Pa/235U), attests a relatively recent and important uranium migration,concordant dates cannot guarantee closed-system behavior of a sample. The results of 20 fossil bones from 10 Chinese sites, 19 of which are determined by two U-series methods, are given.Judging from independent age controls, 8 out of the 11 concordant age sets are unacceptable.The results in this paper suggest that uranium may cycle into or out of fossil bones, such geochemical events may take place at any time and no known preserving condition may securely protect them from being affected. So for the sites we have studied, the U-series dating of fossil bones is of limited reliability.
