热液金矿床中黄铁矿LA-MC-ICP-MS原位微区硫、铁同位素分析方法

Pyrite (FeS2) is the main gold-bearing mineral in the hydrothermal gold deposits. Its sulfur and iron isotopic compositions can effectively trace the sources of ore-forming materials and detailed metallogenetic processes, which are the key issues to study the metallogenesis of hydrothermal gold deposits. This project aims to establish the analytical methods of in situ sulfur and iron isotopic analyses for pyrite, respectively, using a Neptune MC-ICP-MS equipped with a 193 nm excimer laser, based on the study of suitable pyrite standards. The notable issue is the influencing factors, such as the matrix effects and mass bias. Calibration methods for these factors will be set up. Moreover, after investigating element and isotope fractionations when the ablated materials are split into two parts, we will establish an in situ simultaneous measurement method for sulfur and iron isotopes of pyrite using two MC-ICPMS and one 193nm excimer laser. Then, we will apply this technique to measure sulfur and iron isotopic components of pyrites in each mineralizing stages from the Shicheng gold deposit in the Jiaodong peninsula and use the coupled Fe and S isotopic compositions to constrain the sources of ore-forming materials and metallogenentic processes of gold deposit.

黄铁矿（FeS2）是热液金矿床中主要载金矿物，其硫、铁同位素组成可有效示踪成矿物质来源和成矿过程，对于认识热液金矿床的成因至关重要。本项目拟利用193nm准分子激光剥蚀系统与多接收电感耦合等离子体质谱联机技术（LA-MC-ICP-MS），研发黄铁矿硫、铁同位素原位微区分析标样，系统研究LA-MC-ICP-MS测定硫、铁同位素过程中的干扰因素，创建相应的干扰校正方法，分别建立黄铁矿的硫、铁同位素原位微区分析方法，并采用两台多接收等离子体质谱和一台193nm激光联机，详细研究剥蚀物质在被分为两份过程中是否产生元素和同位素分馏，建立同时测定硫和铁同位素的分析方法。最后，以胶东石城金矿床为例，利用建立的方法分析不同成矿阶段的黄铁矿原位微区硫和铁同位素组成，详细探讨该矿床的成矿物质来源和精细的成矿过程。

在热液金矿床中，黄铁矿（FeS2）的硫、铁同位素组成可有效示踪成矿物质来源和成矿过程，对于认识热液金矿床的成因至关重要。本项目建立了5个黄铁矿Fe和S同位素分析实验室参考标样。研究中发现位置效应是高精度测定稳定同位素组成的主要障碍之一，为克服位置效应的影响，研发了一个均一气流剥蚀池。在此基础上建立了LA-MC-ICPMS原位微区高精度测定分别测定黄铁矿中硫和铁同位素的分析方法，以及利用联机分析技术原位微区高精度同时测定黄铁矿中硫和铁同位素的分析方法，56Fe和34S的分析精度为0.2‰ (2SD)。以胶东石城金矿床为例，利用建立的方法分析了不同成矿阶段的黄铁矿原位微区硫和铁同位素组成，探讨该矿床的成矿物质来源和精细的成矿过程。