内蒙古维拉斯托铅锌矿床成矿流体地球化学特征及矿床成因

发布时间：2018-06-08 16:54

本文选题：内蒙古 + 维拉斯托　；参考：《吉林大学》2017年硕士论文

【摘要】：维拉斯托铅锌矿床位于内蒙古赤峰市克什克腾旗白音查干境内,发育在大兴安岭南段西坡成矿带内。本文在整合分析前人研究成果的基础上,对维拉斯托铅锌矿床的地质特征进行了总结,详细研究了矿床流体包裹体的特征,通过研究流体包裹体岩相学、显微测温学和地球化学性质,讨论了成矿流体来源、地球化学特征及演化,深入总结了矿床成因。矿区内出露地层相对简单,除第四系外,仅出露宝音图组下岩段黑云斜长片麻岩、少量石炭系石英闪长岩;研究区内构造特征与区域构造特征相似,矿区内有多期褶皱、断裂构造,矿体受到断裂控制的特征十分明显,主矿体严格受近东西向的“S”型压扭断裂控制;矿区内岩浆岩主要为石炭纪的石英闪长岩脉和海西期侵入岩。根据矿体构造、矿石构造以及矿物共生组合,将维拉斯托铅锌矿床热液的矿化作用过程划分为三个阶段,Ⅰ石英-毒砂-黄铁矿阶段;Ⅱ多金属硫化物-石英阶段;Ⅲ石英-碳酸盐阶段。通过对蚀变类型及其分布规律的分析得出,维拉斯托铅锌矿床存在多种围岩蚀变,如硅化、绿泥石化、绢英岩化、高岭土化等,其中硅化和绿泥石化与矿石的形成密切相关。根据流体包裹体研究,维拉斯托矿床自早阶段到晚阶段流体包裹体类型以富液相包裹体为主,同时含有富CH4包裹体以及含CH4-CO2的包裹体,均一温度和盐度逐渐降低,并显示成矿流体具有中温、低盐度和低密度的特点。I阶段包裹体完全均一温度为243.1℃~398.5℃,盐度为4.8~12%NaCleqv;II阶段包裹体均一温度为190.0~331.1℃,盐度为3.5~9.1%NaCleqv;III阶段包裹体均一温度为180.0~240.0℃,盐度为3.7~6.7%NaCleqv。激光拉曼光谱分析包裹体成分主要为CO2、CH4和H2O。氢、氧同位素分析结果表明维拉斯托铅锌矿床的成矿流体具有岩浆水和大气降水的混合特征。矿石中金属硫化物硫、铅、碳同位素的分析研究表明,维拉斯托δ34S众值集中在0值附近,这符合岩浆硫的特征,故而认为成矿物质具有深源的特点;维拉斯托矿石铅同位素投影点均在造山带增长线上或其下方,这种趋势线被认为是造山模式的一种特征,且说明矿石铅源于地幔或下地壳,具有混合来源的特征。矿石中δ13CPDB的值介于-19.7‰~-19.1‰之间,综合包裹体中的甲烷成分,本文认为流体中的碳同位素具备水岩反应和岩浆混合的来源特征。维拉斯托铅锌矿是一个典型中温热液脉型矿床,结合大兴安岭南段在早白垩世的构造演化史,本文认为,在造山伸展的环境中,本区地幔(下地壳)岩浆热液,沿着断裂构造裂隙上侵过程中不断与围岩发生反应,形成含矿热液。后期又有大气降水参与,发生了水岩反应,生成CH4等有机质;随着温度压力等外部条件的变化,含矿热液中的成矿元素最终在成矿有利部位富集成矿。
[Abstract]:The Vilas lead zinc deposit, located in the Baiyin Chagan, Hexigten Banner, Chifeng, Inner Mongolia, is developed in the western slope metallogenic belt of the southern part of Greater Khingan Range. Based on the integration and analysis of the previous research results, the geological characteristics of the Vilas lead zinc deposit are summarized, the characteristics of the fluid inclusions in the deposit are studied in detail, and the flow of the fluid is studied. The petrography, microthermometry and geochemical properties of the body inclusions are discussed. The origin of ore-forming fluid, the geochemical characteristics and evolution are discussed, and the genesis of the ore deposits is summarized. The exposed strata in the mining area are relatively simple, except for the quaternary system, only out of the lower rock segment of the exposed treasure map group, a small amount of Carboniferous quartz diorite, and the study area in the study area. The characteristics are similar to the regional tectonic features. There are multi stage folds in the mining area, fracture structures and ore bodies are characterized by fracture control. The main ore body is strictly controlled by the near East-West "S" type compression and torsion fracture; the magmatism in the mining area is mainly Carboniferous quartz diorite vein and Hercynian intrusive rock. In the symbiotic combination, the mineralization process of the hydrothermal fluid in the Vilas Tor lead-zinc deposit is divided into three stages, I. quartz - arsenopyrite phase, II polymetallic sulphide quartz phase, and III quartz - carbonate stage. Through the analysis of alteration types and distribution rules, there are a variety of wall rock alteration, such as silicification, in the Vera stow lead zinc deposit. Green mud petrochemistry, sericite and KAOLINIZATION are closely related to the formation of silicification and chlorinization. According to the study of fluid inclusions, the type of fluid inclusions from the early to late stages of the Vilas bearing deposit are mainly rich in liquid inclusions, including rich CH4 inclusions and CH4-CO2 inclusions, and homogenization temperature and salinity. Gradually decreasing and showing that the metallogenic fluid has the characteristics of medium temperature, low salinity and low density, the complete homogenization temperature of the.I phase inclusions is 243.1 ~398.5 C, the salinity is 4.8~12%NaCleqv, the homogenization temperature of the inclusions in the II phase is 190.0~331.1, the salinity is 3.5~9.1%NaCleqv, the homogeneous temperature of the inclusions in the III phase is 180.0~240.0 C, and the salinity is 3.7~6.7%NaCleqv. The composition of the inclusions is mainly CO2, CH4 and H2O. hydrogen. The results of oxygen isotope analysis show that the ore-forming fluid of the Vilas lead zinc deposit has a mixture of magmatic water and atmospheric precipitation. The analysis of sulphur, lead and carbon isotopes of metal sulfide in the ore shows that the value of Vilas Delta 34S is concentrated near the 0 value, which conforms to this. The characteristics of the magma sulfur, therefore, think that the metallogenic material has the characteristics of deep source; the lead isotope projection points of the Vilas bearing ore are all on the orogenic belt growth line or below it. This trend line is considered to be a characteristic of the orogenic model and that the ore lead is derived from the mantle or lower crust, with the characteristics of mixed sources. The value of the delta 13CPDB in the ore is in the middle of the ore. In this paper, the carbon isotopes in the fluid are considered to have the characteristics of water rock reaction and magma mixing. The Vilas lead and zinc deposit is a typical medium temperature hydrothermal vein type deposit, combined with the early Cretaceous evolution history of the southern part of Greater Khingan Range, which is considered to be in the environment of orogenic extension. In this area, the mantle (lower crust) magmatic hydrothermal fluids constantly react with the surrounding rock during the fracture process of fracture tectonic fractures to form ore bearing hydrothermal fluids. In the later period, there is a water and rock reaction and the formation of CH4 and other organic matter, with the participation of precipitation in the later period, and the mineralization elements in the ore bearing hydrothermal fluid eventually are in the favorable part of the mineralization with the change of the external conditions such as temperature and pressure. Rich integrated ore.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.4

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