静态测量方式的单颗粒锆石蒸发铅同位素定年方法  

Single-grain Zircon Evaporation ^(207)Pb/^(206)Pb Dating Method with Static Measurement Mode

作　　者：王秀丽[1] 李向辉[1] 王芳[1] 李秋立[1] 陈福坤[1] 

机构地区：[1]中国科学院地质与地球物理研究所固体同位素地球化学实验室,北京100029

出　　处：《岩矿测试》2006年第3期201-205,共5页Rock and Mineral Analysis

基　　金：国家自然科学基金资助项目(40372106;40525007);国家教育部留学回国人员科研启动基金项目

摘　　要：报道的单颗粒锆石蒸发定年方法是利用新型固体质谱计的多离子接收器配置实现的。改进的锆石蒸发207Pb/206Pb定年流程通过静态测量方式,在锆石蒸发过程中直接测定铅同位素比值,获得207Pb/206Pb年龄。应用该方法测定了元古代永宁组沉积岩的碎屑锆石,获得6颗锆石的207Pb/206Pb年龄值为1 965~2 590 Ma。与传统的蒸发法流程相比,静态测量方法省时简捷,同时可以直观地观测到锆石内部的铅同位素组成变化。这些变化反映锆石结晶历史、后期事件叠加以及锆石成因等地质信息。The single-grain zircon evaporation method reported in this study has been realized owing to a muhiion-counter configuration equipped in a newly developed mass spectrometer. Using an improved analytical procedure to the traditional zircon evaporation ^207Pb/^206Pb dating, Pb isotopic ratios were simultaneously measured with static mode during evaporating the zircon grain. Six detrital zircon grains from the Proterozoic Yongning Formation were measured using this method and ^207Pb/^206Pb ages of 1965 - 2590 Ma were obtained. Compared with the traditional procedure of the evaporation dating method, this new technique is time-saving and convenient. Variation of Pb isotopic ratios of zircon grain can be directly observed during the evaporation-measurement process. This compositional variation can provide meaningfully geological information of crystallization history, overprint of late geological events and genesis of zircon grains.

关 键 词：单颗粒 锆石定年 蒸发法 静态测量 多离子计数器 

分 类 号：O657.63[理学—分析化学] P597.3[理学—化学]