静态测量方式的单颗粒锆石蒸发铅同位素定年方法

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1965—2590Ma。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。

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

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.