| 陕西大西沟喷流沉积型菱铁矿矿床地质特征及矿床成因 |
| Received:February 08, 2018 Revised:December 01, 2018 点此下载全文 |
| 引用本文：ZHAN HanYu,LI ZhanKe,WU WenHui,LI JianWei.2019.Geological characteristics and origin of Daxigou SEDEX siderite deposit in Shaanxi Province[J].Mineral Deposits,38(1):1~20 |
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| Author Name | Affiliation | E-mail | | ZHAN HanYu | Sichuan Geological Survey, Chengdu 610081, Sichuan, China
Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, Hubei, China | | | LI ZhanKe | Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, Hubei, China | lizk@cug.edu.cn | | WU WenHui | Sichuan Geological Survey, Chengdu 610081, Sichuan, China
Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, Hubei, China | | | LI JianWei | Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, Hubei, China
State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, Hubei, China | |
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| 基金项目:国家自然科学基金项目（编号：41325007、41402066、91514303）的资助 |
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| 中文摘要:陕西大西沟铁矿床位于秦岭造山带山-柞盆地西北部，与银洞子大型银铅矿床毗邻。矿体主要赋存在泥盆系青石垭组中上段，容矿岩石为一套海相复理石碎屑岩和碳酸盐岩建造。矿床的金属矿物主要有菱铁矿、磁铁矿、黄铁矿，其次为黄铜矿、磁黄铁矿等；非金属矿物主要是重晶石、石英、铁白云石，其次为方解石、绢云母、绿泥石、黑云母、斜长石、钠长石、堇青石等，局部地段由于表生氧化和次生富集作用而形成针铁矿、赤铁矿、蓝辉铜矿等。与矿化有关的围岩蚀变较弱，主要有硅化、绢云母化、绿泥石化和碳酸盐化。基于野外地质观察、矿物共生组合和矿石结构构造的系统研究，将大西沟铁矿床的形成划分为3期6阶段，分别是：①喷流沉积期：硅质岩-黄铁矿-菱铁矿阶段（Ⅰ）、重晶石-磁铁矿阶段（Ⅱ）；②热液改造期：堇青石-黄铁矿-磁铁矿阶段（Ⅲ）、石英-碳酸盐阶段（Ⅳ）、碳酸盐-硫化物-磁铁矿阶段（Ⅴ）；③表生氧化期（Ⅵ）。流体包裹体显微测温结果表明，喷流沉积期Ⅰ阶段菱铁矿完全均一温度和盐度w（NaCleqw（NaCleqw（NaCleqw（NaCleqw（NaCleq13CPDB值集中在-3.58‰~-1.15‰之间，δ18OSMOW值为21.22‰~21.82‰，均表现出海相碳酸盐或海底喷流热液溶解海相碳酸盐的特征。大西沟矿床的地质、矿化和流体特征与海底热液喷流沉积型矿床一致，可能属于典型的喷流沉积型菱铁矿床，但后期受到秦岭造山作用的影响及热液叠加改造并形成磁铁矿和少量硫化物。大西沟菱铁矿矿床与邻近的银洞子铅锌矿组成一个较完整的喷流沉积成矿系统，两者可能分别代表了喷流沉积的边缘相和中心相。 |
| 中文关键词:地质学 菱铁矿 流体包裹体 C、O同位素 成矿流体 大西沟 |
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| Geological characteristics and origin of Daxigou SEDEX siderite deposit in Shaanxi Province |
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| Abstract:The Daxigou iron deposit is located in the northwest of Shan-Zha Basin in the Qinling Orogen, adjacent to the Yindongzi Ag-Pb deposit. The orebodies are hosted in the upper section of Devonian Qingshiya Group, which is a set of flysch clastic-carbonate sedimentary formations of marine facies. The metallic minerals consist mainly of siderite, magnetite, pyrite, and chalcopyrite with minor pyrrhotite, hematite, goethite, and digenite. The nonmetallic minerals are dominated by barite, quartz, and ankerite, with a little calcite, sericite, chlorite, biotite, plagioclase, albite, and cordierite. Supergene oxidation has formed some iron and copper supergene minerals, such as goethite, hematite, and digenite. Wall rock alteration associated with mineralization is weakly developed, and is mostly characterized by silicification, sericitization, chloritization, and carbonatization. On the basis of a systematic study of field geological features, mineral paragenesis, ore texture and structure, the mineralization process can be divided into six stages:SEDEX period:the silicolite-pyrite-siderite stage (Ⅰ) and the barite-magnetite stage (Ⅱ); hydrothermal alteration period:the cordierite-pyrite-magnetite stage (Ⅲ), the quartz-carbonate stage (Ⅳ) and the carbonate-sulfide-magnetite stage (Ⅴ), and supergene period (Ⅵ). Fluid inclusion study shows that the temperature and salinity w(NaCleqw(NaCleqw(NaCleqw(NaCleq13CPDB and δ18OSMOW of the carbonate minerals are -3.58‰~-1.15‰ and 21.22‰~21.82‰, respectively, showing the characteristics of marine carbonates or marine carbonate dissolved by seafloor hydrothermal fluids. The geology, mineralization and fluid characteristics of the Daxigou deposit are consistent with features of SEDEX (Sedimentary Exhalative) deposit, and hence it may belong to SEDEX siderite deposit. Subsequently, parts of magnetite and sulfide minerals might have been formed under the influence of Qinling Orogeny and hydrothermal modification. The Daxigou siderite deposit and its adjacent Yindongzi lead and zinc deposit have formed a whole sedimentary deposit system, and may represent the edge phase and the center phase of the sedimentary exhalative system, respectively. |
| keywords:geology siderite fluid inclusion carbon-oxygen isotope ore-forming fluids Daxigou |
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