激光探针等离子体质谱测定单颗粒锆石铀-铅年龄  

Uranium-Lead Age Determination of Single Zircon Grain by Laser Ablation Microprobe-Inductively Couple Plasma Mass Spectrometry

作　　者：梁细荣[1] 李献华[1] 韦刚健[1] 涂湘林[1] 王甘霖[1] 

机构地区：[1]中国科学院广州地球化学研究所,广州510640

出　　处：《分析化学》1999年第10期1121-1125,共5页Chinese Journal of Analytical Chemistry

基　　金：国家杰出青年科学基金(49725309);中国科学院广州分院测试基金资助项目

摘　　要：建立了一种利用激光探针等离子体质谱测定单颗粒锆石U-Pb同位素年龄的新方法.以线扫描进样法代替传统的剥深进样法,克服U/Pb之间的熔蚀分异.对前寒武纪(>1.0Ga)锆石的定年表明,^(207)Pb/^(206)Pb、^(206)Pb/^(238)U定年精密度和准确度均为优于2%.对两颗中生代锆石进行了测试,获得了与SHRIMP,定年一致的^(206)Pb/^(238)U年龄.研究结果表明,该定年方法可与SHRIMP定年方法相比拟.A new method for the determination of U-Pb isotopic dating on zircon grains has been developed by using a laser ablation microprobe (LAM) which coupled to an inductively coupled plasma-mass spectrometry(ICPMS). During the sampling process by the LAM, the conventional depth profile method was substituted by a line-scan method, by which the ablation fractionation between Pb and U could be attenuated. The 207Pb/206Pb and 206Pb/238U ages can be determined simultaneously for zircon grains of Precambrian, both the precision and relative error of the 207Pb/206Pb and 206Pb/238U ages for the determination are less than 2%. Our 206Pb/238U ages for the two Mesozoic zircons (Siberian-1 andSiberian-2) are 150±4Ma, and 148±3Ma, which agree with their SHRIMP ages. It demonstrates thatthe presented method may be comparable with the SHRIMP for homogenous zircons.

关 键 词：LAM ICPMS 锆石 铀 铅 同位素年龄 定年 

分 类 号：P575[天文地球—矿物学]