激光剥蚀-电感耦合等离子体质谱实现黄铁矿中多元素原位成像

采用激光剥蚀-电感耦合等离子体质谱( LA-ICP-MS)建立了单粒黄铁矿的多元素原位成像方法。在1mm×1mm的扫描区域内,获得有效计数点信息约5万个,总分析时间仅为1.5h。结果表明,此粒黄铁矿表面Fe、S元素的信号强度分布均匀,Fe/S比值数据集中,相对标准偏差仅为11.6%,这表明黄铁矿均质性较好,也表明本分析方法的稳定性较高。相对于围岩,黄铁矿表面的微量元素表现出的富集或亏损特征,可能与黄铁矿形成时的氧化还原环境和后期的次生改造作用有关。本方法将有助于LA-ICP-MS在单颗粒矿物分析中的推广应用,可为古环境、烃源岩和流体成藏等研究提供更直接、更准确的可视化实验数据。

In situ Imaging of Multi-elements on Pyrite Using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

A method of in situ multi-elements 2 D imaging on single pyrite was developed using laser ablation-inductively coupled plasma-mass spectrometry ( LA-ICP-MS ) . Nine elements and nearly 50 thousands valid data were acquired in a 1 mm × 1 mm scanning area, with the total analyzed time of 1. 5 h. The data showed that, the signals of Fe and S were uniformly distributed on the pyrite, and the ratio data of Fe/S was centralized with a lower relative standard deviation of 11 . 6%, indicating the good homogeneity of this pyrite and stability of this method. Compared to the surrounding black shale, the detected trace elements on the pyrite showed different degrees of enrichment or loss, which might be the response of redox environment during this pyrite forming or the later secondary reforming process. The method will help for the popularization and application of LA-ICP-MS in single mineral particles analysis, and provide more direct and accurate visual data for the study of paleoenvironment, source rock and fluid accumulation.