锆石稀土元素TOF-SIMS微区原位分析方法

Zircon's rare earth elements are critical to petrogenesis, crustal evolution and metallogenesis. Rare-consuming in-situ analysis of rare earth elements in complex structured zircon and interference of LREE oxides on HREE are still difficult problems that bothering geologists. This project aims to establish a new method for the in-situ and rare-consuming analysis of rare earth elements in zircon based on TOF-SIMS technology. Using the TOF-SIMS instrument developed by ourselves , by optimizing the key components and developing new technologies to improve the sensitivity of the instrument, a flow chart of zircon characteristics-based in-situ REE analysis will be explored and established. Further on, various standards will be analyzed for calibration in matrix effect and instrumental fractionation, expecting constraining future analytical works. The new method will provide technical methods for solving many scientific problems including, identification of reworking or overgrowth of hydrothermal zircon, evolutionary history of metamorphic zircon, tracing the source and tectonic environment based on zircon REE.

锆石中稀土元素对岩石成因、地壳演化，以及成矿作用等具有重要的指示意义。结构复杂锆石稀土元素的微区无损分析和轻稀土氧化物对重稀土干扰问题是困扰地质学家的重要难题。本项目旨在开发基于飞行时间二次离子质谱（TOF-SIMS）技术的锆石微区无损稀土元素分析新方法。利用自主研发的TOF-SIMS仪器，通过核心部件优化与关键技术开发来提升检测灵敏度，拟建立基于锆石特点的稀土分析流程，并研究多种标样对基质效应与仪器分馏的校准效果，以期指导后续实验。该方法的建立，将为锆石的热液改造和新生热液锆石识别、变质锆石的演化历史、以及锆石稀土元素源区示踪和构造环境示踪等多个科学问题的解决提供新的技术手段。

TOF-SIMS仪器是我国首个自主研发的大型二次离子质谱，分析方法开发是当前工作的重点。本项目利用的TOF-SIMS科学仪器，建立了锆石稀土元素微区分析新方法。针对典型矿物的主微量元素含量的特点，开展了TOF-SIMS离子传输效率优化改进，包括二次离子提取系统、离子偏转等部件。开发了稀土元素分析从制靶、前处理，到上机、分析参数设定，再到数据获取、处理等实验流程。针对不同干扰谱峰差异，建立了微量元素数据处理方法，包括高精度谱峰质量标定和TOF-SIMS基质效应校准等方法。初步完成了月球陨石样品TOF-SIMS分析，为进一步的后期实验推广开展了大量的前期基础分析实验，这些工作可支持后期TOF-SIMS仪器的应用与推广。