河南嵩县磨沟金矿床成因

发布时间：2018-03-01 14:13

  本文关键词： 矿床地质 流体包裹体 稳定同位素 矿床成因 磨沟金矿　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：磨沟金矿位于华北地块南缘熊耳山-外方山地区,华北陆块南缘是我国第二大金矿产地。本文在收集熊耳山地区前人研究资料的基础上,对矿床的地质特征、C-H-O-S稳定同位素地球化学特征以及流体包裹体等特征等进行了详细的研究,探讨了磨沟金矿成矿物质来源和成矿流体的特征、演化和来源,解析矿床成因和成矿机制,论文取得的主要认识概括如下:(1)磨沟金矿床的矿体主要赋存于熊耳群火山岩中,呈脉状受北东向断裂控制。围岩蚀变以硅化为主,其次为钾化、碳酸盐化和高岭土化等。矿石结构主要有自形-半自形晶粒状结构、乳滴状结构和侵蚀结构等。矿石构造主要有浸染状构造和脉状构造等。热液活动划分为石英?黄铁矿阶段、石英?多金属硫化物阶段和石英?碳酸盐阶段。(2)磨沟金矿床流体包裹体类型以气液两相包裹体和含CO2三相包裹体为主。形态主要有方形、椭圆形和月牙形等。包裹体成分有CO2、CH4、H2O和H2S等。包裹体完全均一温度峰值从220~280℃到160~220℃最后再到160~180℃逐步演化;盐度主体范围从8~16wt.%Na Cl.eqv到6~12wt.%Na Cl.eqv再到0~8wt.%Na Cl.eqv;密度从0.82~1.09g/cm~3变化到0.89~0.98 g/cm~3再演化到0.89~0.97 g/cm~3。成矿压力峰值在20~30 MPa范围内,成矿主阶段压力均值为27.48MPa;成矿深度峰值在2~3 km范围内,成矿主阶段深度均值为2.76km。成矿流体总体上显示中温、中低盐度和低密度的特征。(3)磨沟金矿C-H-O同位素分析表明成矿流体来源于变质水和大气水的混合。S同位素分析显示成矿物质来源于重熔的太华群。通过与典型金矿床的地质和地球化学特征对比,磨沟金矿属于造山型金矿。沸腾作用和水岩反应是金矿沉淀的主要机理。成矿流体携带来自重熔太华群的成矿物质通过马超营断裂等导矿构造运移至其北东向次级断裂,通过沸腾作用和与熊耳群地层的水岩反应,流体与大气降水混合,萃取了部分熊耳群的成矿物质,并在合适的位置沉淀成矿。
[Abstract]:Mogou gold deposit is located in Xiongershan-Waifangshan area on the southern margin of North China block, and the southern margin of North China block is the second largest gold deposit in China. The geological characteristics of the deposit and the characteristics of stable isotopic geochemistry of C-H-O-S and fluid inclusions are studied in detail, and the characteristics, evolution and origin of ore-forming materials and ore-forming fluids in Mogou gold deposit are discussed. By analyzing the genesis and metallogenic mechanism of the deposit, the main knowledge obtained in this paper is summarized as follows: (1) the orebody of the Mogou gold deposit mainly occurs in the volcanic rocks of Xiong er group, and is controlled by NE faults. The main alteration of surrounding rock is silicification, followed by potassium. Carbonation and kaolinization. The ore structure mainly consists of self-shape and semi-automorphic grain structure, emulsion droplet structure and erosion structure, etc. The ore structure is mainly dyed structure and vein structure, etc. The hydrothermal activity is divided into quartz? Pyrite stage, quartz? Polymetallic sulphide stage and quartz? In carbonate stage, the fluid inclusions in Mogou gold deposit are mainly gas-liquid two-phase inclusions and CO2 three-phase inclusions. The inclusions are composed of CO _ 2H _ 4H _ 2O and H _ 2S. The peak values of the complete homogenization temperature range from 220 ~ 280 鈩，

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