【作者】 吴迪；

【导师】 刘建朝；

【作者基本信息】 长安大学 ， 矿物学、岩石学、矿床学， 2016， 硕士

【摘要】 夏甸金矿床位于胶西北地区,是招平断裂带上的一个大型金矿。本文结合前人研究成果,通过对夏甸金矿床矿床地质特征、蚀变分带、蚀变围岩地球化学特征、成矿阶段流体包裹体特征、成矿物质来源等方面的研究来探讨蚀变与成矿之间的关系以及矿床的成因模式,以期为学者今后的研究提供一些帮助。通过分析矿床地质特征,认为夏甸金矿矿体的展布受招平断裂带的控制,形态多呈透镜状、扁豆状。矿石结构构造相对复杂,常见结构为自形晶粒状结构、半自形-他形晶粒状结构、侵蚀结构、交代残余结构、压碎结构、包含结构、乳滴状结构等;构造主要包括细脉-网脉状构造、浸染状构造、角砾状构造等;金主要以自然金、银金矿等形式嵌布于黄铁矿、闪锌矿、方铅矿和黄铜矿等硫化物中。对矿体及矿化蚀变类型的研究,将蚀变划分为六个蚀变带,结合蚀变带的岩石地球化学特征,认为钾长石化与金矿的形成无直接关系,硅化与黄铁矿化与成矿关系最为密切。在研究矿体产状、规模、品位,矿石的矿物成分、结构构造、矿石类型,脉体及矿物的共生组合、穿插关系、包含关系、溶蚀关系,围岩蚀变类型等的基础上将夏甸金矿的成矿划分为四个阶段。通过对四个阶段流体包裹体的岩相学、类型、温度、压力、盐度、密度及成分特征的研究,认为夏甸金矿的成矿流体为含少量CH4、C4H6的CO2-H2O-Na Cl体系,成矿早阶段至晚阶段包裹体的类型从气液两相包裹体变为液相包裹体,且温度、压力、盐度不断降低。氢、氧同位素测试结果显示夏甸金矿的初始成矿流体为岩浆水,随着成矿作用的进行,大量的大气降水混入,到了成矿末极端,大气降水成为主导。硫同位素特征显示该区的硫源具有继承性,矿石硫同为素的范围介于郭家店花岗岩与胶东岩群之间,暗示其来源可能为郭家店花岗岩与胶东岩群的混合。铅同位素特征显示,矿石Pb来源与地幔与造山带的混合,并有继承胶东岩群铅的特点。更多还原

【Abstract】 Xiadian gold deposit, which is located at the Northwest Jiaodong, and bounded on the middle of the Zhaoping fault, is a large tectonic alteration gold deposit. Consulting the literatures and earliest formal geological survey, this paper conducts outfield and regional geological survey, ore field geological researches, structure analysis, petrography study, trace element analysis, fluid inclusion tracing, stable isotope analysis and so on, to analysis the relationship between alteration and mineralization, and the ore genesis.By analysis the Geological characteristics of the deposit, author consider that Zhaoping fault controls the form of Xiadian gold deposit. Texture and structure of ores are complexity, sight texture include euhedral crystal-granular, subhedral-allotriomorphic granular texture, metasomatic relict texture, pressure texture, poikilitic texture, emulsion droplet, etc; sight structure, massive structure, disseminated structure, brecciated structure, spotted structure, fine vein structure, vesicular structure. Gold is mainly disseminated in pyrite, aphalerite, galena, chalcopyrite and other sulfides. The alteration types of ore bodies and wall rock are divided into six alteration zones. Combined with the alteration geochemistry, we suggest that there is no direct relationship between K-feldspar and the formation of gold deposit. Silicification and pyrite is the most important factor in the formation f Xiadian gold deposit.Subject to the researches on the occurrence, scale, and grade of the ore body, the component of ore, structure, ore types, alteration types and alteration zoning, Xiadian gold mineralization is divided into two periods and four stages. Analysis of fluid inclusions, including petrography, type, temperature, pressure, salinity, density and characteristics of compositions in the four stages, indicate that, from the early to late stage,(1)the inclusions evolve from the gas+vapor inclusions to the liquid inclusions;(2) temperature, pressure and salinity keep to fall down;(3) Fluid inclusion reflect Xiadian Gold Deposit ore-forming fluid belong to CO2-H2O-NaCl system.The results of hydrogen-oxygen isotope data show that the genesis of ore-forming fluids in the Xiadian gold deposit come from magmatic fluids at the early stage, then mostly the meteoric water. The results of sulfur isotopes show that the sulfur in the Xiadian gold deposit area is inheritable and the sulfur isotope range is between Linglong granite and Jiaodong group, which suggests that the sulfur here apparently comes from the mixing of them. Lead isotopes also show that the genesis of ancient lead had the identical inheritance as sulfur isotopes, and lead isotopic data shows that the genesis of the lead might come from the crust and the mantle.更多还原