锇-锇测年方法研究  

Study on OsOs Dating Method

作　　者：高洪涛[1,2] 赵敦敏[1,2] 杜安道[1,2] 屈文俊[1,2] 刘敦一 

机构地区：[1]中国地质科学院岩矿测试技术研究所 [2]中国地质科学院地质研究所

出　　处：《岩矿测试》1999年第3期176-181,共6页Rock and Mineral Analysis

基　　金：地质矿产部实验基金

摘　　要：采用负离子热电离质谱（ＮＴＩＭＳ）和等离子体质谱（ＩＣＰ－ＭＳ）技术建立了１８７Ｏｓ１８６Ｏｓ和１８７Ｏｓ１８８Ｏｓ测年方法。方法基于利用核反应１８５Ｒｅ（ｎ，γ）１８６Ｒｅ和１８７Ｒｅ（ｎ，γ）１８８Ｒｅ所产生的１８６Ｒｅ和１８８Ｒｅ分别经过β衰变生成稳定同位素１８６Ｏｓ和１８８Ｏｓ。１８６Ｏｓ和１８８Ｏｓ的生成量由照射参数和样品中Ｒｅ含量决定。只要测定Ｏｓ同位素比值就可计算出Ｒｅ含量和ＯｓＯｓ年龄。以年龄参考样ＨＬＰ为标准，ＮＴＩＭＳ测定了陕西金堆城斑岩钼矿中辉钼矿（ＪＤＣ）的ＯｓＯｓ年龄。ｔ１８６＝１３９．１Ｍａ±０．７Ｍａ（２σ）与本实验室ＩＣＰ－ＭＳ方法ＲｅＯｓ年龄测定值１３９Ｍａ±６Ｍａ（２σ）以及美国地调局ＮＴＩＭＳ方法ＲｅＯｓ年龄测定值１４０．１Ｍａ±１．A Recontaining sample is irradiated with thermal neutron in a nuclear reactior. The following reactions occur with high cross sections: 185Re(n,)186Re and 187Re(n,)188Re. Both 186Re and 188Re decay to 186Os and 188Os stable isotopes. The 186Os and 188Os yields depend on the neutron fluence and the Re contents of the sample being irradiated. So the OsOs age could be obtained from Os isotopic ratio. The 186Os187Os age for JDC molybdenite sample is 139.1Ma0.7 Ma (2), which is in good agreement with the ReOs age of 139Ma6 Ma by Lab. of IRMA and ReOs age of 140.1Ma1.0 Ma by Lab. of USGS.\=\=

关 键 词：等离子体质谱 锇-锇测年方法 地质年代 

分 类 号：P597[天文地球—地球化学]