有机质对黄铁矿Re-Os体系的影响机制

随着分析技术的进步，Re-Os同位素定年对象已经从高Re含量的辉钼矿拓展到黄铁矿等低Re含量的其他热液硫化物，为厘定中低温矿床成矿时代提供了重要手段。本次统计发现不同矿床中热液硫化物的Re含量差异很大，一些沉积岩容矿铅锌矿和铜矿的硫化物Re含量系统偏高，已有的一些研究显示有机质参与可能导致了上述现象，但缺少直接证据。因有机质Re、Os含量高，其参与还可能扰动低含量硫化物Re-Os体系，导致年龄“失真”，但目前缺少识别有机质影响的有效标志。为此，本申请在前期重要发现的基础上（在金顶黄铁矿中发现了有机质参与的显微结构和Re-Os同位素证据），选择金顶黄铁矿为研究对象，联合使用多种原位分析技术，以黄铁矿内Re含量、有机质包体、硫同位素组成和显微结构的分布特征及耦合关系为研究突破口，揭示沉积岩容矿矿床中有机质对黄铁矿Re-Os体系的影响机制，为黄铁矿Re-Os定年的可靠应用提供研究范例及理论依据。

With the development of analytical techniques, the application of Re-Os dating have been expanded from high-level molybdenite to some low-level hydrothermal sulfides, such as pyrites. This method has become a useful tool to directly yield the age of medium-low temperature deposits. The statistic on Re-Os data show that sulfides from some sediment-hosted deposits (MVT and SHC) have significantly higher Re level than that from other deposit types. Some studies have shown that organic matters appear to cause above the Re abnormal, but lack of direct evidence. Moreover, the involvement of high-level organic matters may disturb the Re-Os system of low-level sulfides and causes distorted dating results, which is hard to be identified without appropriate indicators. Recently, micellar structures and high-radiogenic initial Os signals were found in the breccia-type pyrite from the Jinding Pb-Zn deposit by our pilot study, implying the involvement of organic matters. Therefore, We plan to investigate the spatial distribution of Re concentration, organic inclusions, δ34S and micro-structure in these pyrite, with the aid of several state-of-the-art in-situ analysis techniques, aiming to clarify the influence mechanism of organic material on Re-Os system in pyrites, and provide a model and theoretical basis for the application of deposit Re-Os dating.