绿帘石激光原位Sr同位素分析方法研发

Epidote is widely distributed in different types of rock in nature. As an accessory mineral, it records the complex geological processes including magmatism, metamorphism or hydrothermal activtity of its host rocks. This mineral typically incorporates considerable amounts of Sr, but has very low Rb content, which makes it suitable for in-situ micro-analysis of Sr isotope. Sr isotopic composition of epidote can effectively constrain the petrogenesis and source, and reveal complex geological processes in micro-scale. This project will use the multiple-collector (MC) ICP-MS equipped with 193nm GeoLas laser to set up in-situ Sr isotopic analytical method in our lab. Based on development of epidote standard for in-situ Sr isotopic analysis, we will evaluate factors that affect the precision and accuracy of in-situ Sr isotopic data and develop their correction procedures. The aim of this project is to establish a high-precision, accurate in-situ Sr isotopic analytical method using LA-MC-ICP-MS in our lab for geologists to provide an experimental platform.

绿帘石广泛分布于自然界的各种岩石之中，作为副矿物它记录了寄主岩石的岩浆、变质或热液等复杂地质过程。绿帘石是一种富Sr贫Rb矿物，适合于微量和微区Sr同位素分析，其Sr同位素组成可有效示踪岩石成因、源区，从微观角度探索复杂地质过程。本项目拟利用申请者所在MC-ICP-MS实验室的193nm激光剥蚀系统和Neptune Plus多接收等离子体质谱，在研制微区原位Sr同位素分析绿帘石标准的基础上，探索绿帘石Sr同位素测定过程中的影响因素，开发相应的干扰校正程序，建立高精度的绿帘石原位微区Sr同位素分析方法。

绿帘石广泛分布于自然界的各种岩石之中，作为副矿物它记录了寄主岩石的岩浆、变质或热液等复杂地质过程。绿帘石富集轻稀土元素,亏损重稀土元素,Ca离子常常和Sr形成类质同相替换，所以绿帘石一般都富集Sr贫Rb，是原位微区Sr同位素分析的良好对象，能够为认识岩浆、变质或热液演化过程提供依据，例如研究岩浆结晶过程、不同岩浆的混合作用、岩浆同化混染过程及水-岩相互作用等过程。然而，绿帘石与其他副矿物（例如钙钛矿、异形石及方解石等）不同，其原位微区Sr 同位素分析在国际上少有研究。通过本项目的实施，我们研制了绿帘石Sr同位素分析标样，建立了相应的分析方法，并应用这一分析方法对华南东南沿海的白垩纪早期南山岩体中的绿帘石进行了Sr同位素的研究，为限定岩浆期后水-岩相互作用提供了关键性的制约。.