西拉沐伦钼矿带车户沟低氟体系斑岩钼（铜）矿床岩浆-热液转换、成矿流体演化与钼-铜分异富集机制研究

This study chooses the Melt Inclusions, Melt-Fluid Inclusions and Fulid Inclusions as the study objects which are hosted in the magmatic-hydrothermal transition stage (e.g. quartz phenocrysts, quartz ‘eyes’) and and various hydrothermal veinlets of the Chehugou porphyry molybdenum (copper) depsoit in the Xilamulun molybdemum metallogenic belt in the collisional orogen setting. Based on the systemically established fluid evolution sequences, modern analytical methods such as optical microscopy, SEM-CL method, electronic microprobe, high temperature thermo-stage, cooling and heating stage, laser Raman microprobe, and LA-ICP-MS will be used to determine the macromorphology, occurrence and assemblage characteristics of the inclusions; Meanwhile, the temperature and the ore-foming element contents of exsolved fluid will be quantitatively identified. While, the charateristics of exsolved fluid as well as the temperature, salinity, composition and physi-chemical conditions of ore-forming fluid duiring its evoluton will also be ascertained; Determination of major and trace element contents of quartz combined with contents of the ore-forming elements analyses in the magmatic-hydrothermal transition stage, based on which to deduce the origin of the quartz in the magmatic-hydrothermal transition stage as well as the nature of the exsolved fluid. Based on the above research results, it will be intended to discuss the ore-foming elements partition behaviors during the immiscible between magmatic fluid and the sillicate melts as well as immiscible between fluid phase and gas phase and to discuss the molybdenum –copper separation-enrichment mechanism. This study will provide scientific basis for further understanding fluid mineralization mechanism of porphyry molybdenum(copper) in the collisional orogen setting as well as the genetic relationship between ‘Satallite Vein’ and the Porphyry System.

本研究以西拉沐伦钼矿带车户沟斑岩型钼(铜)矿床中岩浆-热液转换阶段石英及流体出熔后各类热液脉系中赋存的熔融包裹体、熔流包裹体和流体包裹体为研究对象。在系统建立流体演化序列的基础上，运用光学显微镜、电子探针、高温热台、冷热台、激光拉曼探针和单颗粒包裹体LA-ICP-MS等现代测试分析手段，确定各类包裹体的微观形态、赋存状态和组合特征；定量化的查明出溶流体形成温度、成矿元素含量及流体出溶演化过程中成矿元素迁移、沉淀期流体温度、盐度、成分特征及物理化学条件；查明流体出熔结构中石英的主量及微量元素含量及赋存包裹体的成矿元素含量，判别流体出溶结构成因。在此基础上，探讨不混溶过程中成矿元素在熔体相-流体相、气相-液相之间的分配规律以及不同流体演化路径对钼、铜元素分异富集机制的控制作用，为深入理解“卫星”脉体与斑岩系统之间的成因联系及碰撞造山环境斑岩型钼(铜)矿床流体成矿作用机制提供科学依据。

本项目选择碰撞造山环境下产出的车户沟低氟斑岩型钼（铜）矿床作为研究对象，针对提出的关键科学问题，按计划书内容、分年度完成了为期三年的研究工作，主要取得以下研究成果：（1）通过详实的野外调研，详细刻画了车户沟矿区岩浆侵位序列、围岩蚀分带特征、精细划分了北区斑岩型钼（铜）和南区脉型铜（钼）矿两种矿化类型不同期次热液脉系类型和流体成矿阶段。（2）基于细致的流体包裹体岩相学、显微测温和原位单颗粒流体包裹体LA-ICP-MS成矿元素含量研究，在系统讨论南北两种矿化类型不同成矿阶段包裹体组合特征、Cu-Mo元素迁移沉淀机制和流体P-T-X演化路径的基础上，提出：铜钼元素分配行为、流体不混溶作用、容矿构造性质差异和不同的流体演化路径是控制研究区铜-钼两种元素分离富集的关键机制。（3）南北两种矿化类型不同成矿阶段原位硫化物LA-ICP-MS硫-铅同位素研究和成矿花岗斑岩锆石原位Hf同位素研究结果表明：两种矿化类型具有一致的成矿物质来源，主要源于加厚新生下地壳部分熔融形成的成矿花岗斑岩的出溶流体。（4）系统分析厘定了中国东北钼矿省三叠纪-侏罗纪三期斑岩型钼矿床的成矿构造背景：早-中三叠世与古亚洲洋闭合有关的碰撞造山环境、早-中侏罗世与古太平洋西向俯冲增生有关的陆缘弧环境和晚侏罗世与古太平洋板块后撤有关的弧后伸展环境。（5）本项目资助发表与中国东北钼矿省钼成矿作用相关的国际SCI论文2篇，国内期刊论文1篇。