微区原位LA-MC-ICP-MS铅同位素分析研究进展

Recent Progress of in Situ Analysis of Pb Isotopes by Using Laser Ablation Multi-Collector ICP Mass Spectrometry

微区原位同位素分析是近年来同位素地球化学研究的前沿领域。其中,激光剥蚀系统与多接收电感耦合等离子体质谱联用技术(LA-MC-ICP-MS)被广泛应用于不同同位素体系和不同天然矿物的微区原位同位素测定。铅同位素作为有效的地球化学示踪手段被广泛用于岩石成因和演化、成矿时代、成矿物质来源、环境污染物源示踪和考古学等研究。目前多利用LA-MC-ICP-MS测定硅酸盐矿物、硫化物矿物和包裹体Pb同位素组成。该方法省略了冗长的化学处理流程,提高了工作效率,并且通过对不同矿物或同一矿物中不同结构部位进行微区原位Pb同位素分析,可揭示微米尺度上的Pb同位素组成变化,为解决地质问题提供了重要的证据。本文评述了近年来地质样品中LA-MC-ICP-MS测定Pb同位素的方法改进及其在部分地球科学研究中的应用。

In recent years,in situ isotope analysis has become a frontier in isotopic geochemistry research.The multi-col- lector inductively coupled plasma mass spectrometry coupled with laser ablation system (LA-MC-ICP-MS)is widely used to in situ determine isotopic compositions of various isotopic systems and various natural minerals.As a highly effective geo- chemical tracer and a valuable geochronological tool in geoscience,the Pb isotope system has been widely applied to study genesis and evolution of magmatic rocks,timing of ore formation,source of ore-forming materials,source of environmental pollutants,and archaeology.At present,the in situ Pb isotopic measurement of silicate and sulfide minerals and fluid in- clusions by using LA-MC-ICP-MS has attracted attentions of many researchers.Comparing to the traditional methods,this method has omitted a lengthy chemical process of purification and improved work efficiency.The in situ analysis of Pb iso- topes of various minerals and/or various textural points of the same mineral by using this method has revealed the interand intra-crystalline isotopic variations of mineral grains on the scale of tens of microns and provided important data and evidences for solving geological problems.This study has reviewed recent development of the method for analyzing Pb isotopes of geological samples by using LA-MC-ICP-MS and some applications of this method in Earth sciences.