东天山地区海相火山岩型铁矿硫化物成因机制研究—以多头山铁铜矿床和百灵山铁矿床为例

As an important component of the Eastern Tianshan, the Aqishan-Yamansu metallogenic belt contains numerous copper-bearing and copper-barren submarine volcanic-hosted iron deposits. Previous works have mainly focused on the geodynamic setting and metallogenic mechanism of the iron ores. However, the metallogenisis of sulfide precipitation in these iron deposits are still poorly understood. In this application, we will take the Duotoushan iron-copper deposit and the Bailingshan iron deposit as the research subject. Based on integrated study on paragenesis of sulfide, in situ distributions of trace elements and sulfur isotope in sulfide from multiple stages will be systematically analyzed, trying to figure out the source(s) and evolution of ore forming fluids at the Duotoushan and Bailingshan deposits. Therefore, we will further reveal the prominent factors controlling the deposition of copper during the mineralization via contrastive study. This project will provide not only constraints on sulfide precipitation processes of the Duotoushan and Bailingshan deposits, but also be valuable for the metallogenetic process of the submarine volcanic-hosted iron deposits in the Eastern Tianshan.

东天山地区的阿齐山-雅满苏成矿带广泛发育着富铜和贫铜两种类型的海相火山岩型铁矿床，以往的研究主要侧重于成矿地球动力学背景和铁矿石的形成机理，对硫化物的成因机制研究相对较弱。本申请拟以多头山铁铜矿和百灵山铁矿的硫化物为对比研究对象，在已有工作的基础上，进一步完善硫化物的形成世代，并以此为依托展开硫化物的原位硫同位素和微量元素分析，探讨各阶段硫化物的成因机制，进而揭示多头山矿床富铜而百灵山矿床贫铜的关键控制因素。本项目的实施及其预期成果，不仅能为多头山和百灵山矿床的硫化物成矿机理提供约束，还有助于完善东天山地区海相火山岩型铁矿的成矿理论。

东天山地区的阿齐山-雅满苏成矿带广泛发育着富铜和贫铜两种类型的海相火山岩型矿床，以往的研究主要侧重于成矿地球动力学背景和铁矿石的形成机理。然而，是什么因素控制着多头山矿床富铜而百灵山矿床贫铜仍不清楚。本项目通过分析矿床地质特征、蚀变矿化期次、成矿年代学及流体演化特征，完善了百灵山和多头山矿床成矿机理的认识，提出了多头山矿床富铜而百灵山矿床贫铜的关键控制因素。.榍石U-Pb年代学研究结果表明，这两个矿床均形成于302~311 Ma之间；H-O同位素结果显示，两个矿床的磁铁矿均形成于高温环境下，初始的成矿流体为岩浆水。而到了硫化物形成阶段，两者的流体则具有较大的差异。黄铁矿原位S同位素结果显示，百灵山铁矿床黄铁矿δ34S（+0.5‰~+3.7‰）属于岩浆硫，而多头山矿床黄铁矿则具有较高的δ34S值（+5.7‰~+12.1‰），显示出海水的特征。此外，多头山矿床黄铜矿具有较高的δ65Cu值（+0.05‰~+0.13‰）。综合考虑该成矿带在石炭纪存在一个有限的洋盆，提出外来盆地卤水是否进入成矿系统可能是导致该类型矿床是否富Cu的关键控制因素。本项目的研究成果，不仅识别出了百灵山铁矿和多头山铁铜矿床成矿作用的差异性，还完善了东天山地区海相火山岩型矿床的成矿理论。