LA-MC-ICPMS电气石及白云母原位硼同位素测试方法及应用  

In situ boron isotope analysis method for tourmaline and muscovite by LA-MC-ICPMS and its applications

作　　者：徐洁 张贵宾[1] 李楠 蔺梦 王佳兴 XU Jie;ZHANG Gui-bin;LI Nan;LIN Meng;WANG Jia-xing(Key Laboratory of Orogenic Belts and Crustal Evolution,MOE,Peking University,Beijing 100871,China)

机构地区：[1]北京大学造山带与地壳演化教育部重点实验室,北京100871

出　　处：《岩石矿物学杂志》2020年第3期323-334,共12页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金资助项目(41972056,41622202,91755206);国家重点研发计划项目(2017YFC0601302)。

摘　　要：多接收电感耦合等离子体质谱(MC-ICPMS)与激光剥蚀系统(laser ablation)的联用,为通过单矿物微米尺度的信息示踪地质过程提供了有利工具。作为非传统稳定同位素之一,硼同位素的应用受到地学界日益广泛的关注。本文利用LA-MC-ICPMS的分析优势建立了原位高精度分析高硼矿物电气石和低硼矿物白云母硼同位素的方法,分别使用电气石标准样品和玻璃标准样品对未知样品的测试结果进行了质量歧视校正,并对2个西南天山的实际地质样品进行了微区硼同位素测试应用。测试结果表明,仪器状态可以保持长期稳定,可以采用最小10μm的束斑对实际地质样品中电气石的硼同位素组成进行准确测定,也可对硼含量高于20×10-6的白云母进行原位硼同位素的准确测定;标定的实验室内部电气石标准样品T-PKU的推荐值为-13. 07‰±0. 42‰(2SD,n=66)。天山泥质片岩及脉体中的电气石和白云母的原位硼同位素特征为示踪与矿物平衡共生的流体来源提供了有效信息。The combination of multi-collector inductively coupled plasma mass spectrometry( MC-ICPMS) and laser ablation provides a useful tool for tracing the geological process by analyzing minerals under microscales. As one of the non-traditional stable isotopes, boron isotope has attracted more and more attention. In this study, the authors developed an in-situ method for high-precision analysis of B isotope in tourmaline with high-content boron and muscovite with low-content boron. Tourmaline and glass reference materials were applied to correcting the mass fractionation respectively, and in-situ B isotopes of two natural samples from southwestern Tianshan were also tested. In addition, the boron isotope of the in-house standard T-PKU was calibrated as-13. 07‰ ± 0. 42‰( 2 SD, n = 66).The above testing results reveal that the condition of LA-MC-ICPMS is stable for a long term and suitable to producing high quality data about tourmaline with minimum spot size of 10 μm and muscovite with > 20 × 10-6 B concentration. The B isotopes of tourmaline and paragonite in Tianshan samples are helpful for tracing fluids sources.

关 键 词：LA-MC-ICPMS 硼同位素 电气石 白云母 

分 类 号：P597.2[天文地球—地球化学]