论文摘要
In recent years, the LA-（MC）-ICP-MS in-situ U-Pb dating has been a dominant trend of the U-Pb chronology development, more and more U-bearing minerals have been widely used in LA-（MC）-ICP-MS in situ U-Pb dating. The common lead correction have an important impact on the U-Pb isotopic dating results. It is very important to choose an appropriate common lead correction method in LA-（MC）-ICPMS in situ U-Pb dating. The commonly used methods contain 204Pb、208Pb and 207Pb correction methods. Because it is difficult to accurately measure the 204Pb signal in LA-（MC）-ICP-MS in situ U-Pb dating, the 204Pb correction method is generally not used; The 208Pb correction method is suitable for samples with low Th/U ratio, and the 207Pb correction method is more suitable for younger samples. Meanwhile, the Tera-Wasserburg concordia and the isochronal correction method have been applied more and more in the in-situ LA-（MC）-ICP-MS U-Pb dating of the U-bearing Minerals. Because 204Pb is difficult to measure accurately, 207Pb is used instead of 204Pb for the isochronal correction method. For samples with low U content and high common lead content（common lead content is more than 50% of total lead content）, the 206 Pb/207Pb-238U/207Pb isochron correction method can deduct the common lead better. However, for older samples（such as greater than 400 Ma）, it is not appropriate to use the 206 Pb/207Pb-238U/207Pb isochronal method. It should be noted that the effect of the isotopic fractionation is not taken into account when the isochron correction method is used to duduct common lead. It is necessary to correct the isotopic fractionation effect in order to obtain the accurate U-Pb age. The advantage of the Tera-Wasserburg concordia method is that it can simultaneously correct the common lead and the isotopic fractionation effects. In summary, different methods have different advantages and limitations in deducting the common lead, it is very important to choose an appropriate correction method according to the age range of mineral, total U, Pb content, common lead content and dating accuracy requirement of the sample. For minerals with low common lead content, such as xenotime and monazite, the 207Pb, the isochron and the Tera-Wasserburg concordia methods are generally used to deduct the common lead; The isochronal and the Tera-Wasserburg concordia methods are also better choices for some minerals with high common lead content, such as apatite, titanite, cassiterite,rutile and perovskite.
论文目录
文章来源
类型: 国际会议
作者: ZHANG Yongqing,ZHOU Hongying,GENG Jianzhen,TU Jiarun,XIAO Zhibin,XU Yawen,YE Lijuan
来源: 第九届世界华人地质科学研讨会 2019-06-01
年度: 2019
分类: 基础科学
专业: 地质学,地质学,地质学
单位: Tianjin Centre,China Geological Survey
分类号: P575;P597.3
DOI: 10.26914/c.cnkihy.2019.028524
页码: 434
总页数: 1
文件大小: 56k
下载量: 2