广西南丹县拉么锌铜矿床成因研究

发布时间：2018-04-10 23:09

本文选题：拉么锌铜矿 + 矽卡岩　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：拉么锌铜矿床是丹池成矿带中段大厂矿田内重要的矿床。本文在总结分析前人对该矿床各方面研究成果基础上,通过野外地质调查研究和多种分析测试手段,开展了拉么矿床地质特征、岩石与黄铁矿单矿物微量稀土元素、辉钼矿年代学研究等,对比了两种类型矿体地球化学特征、成矿物质来源、成矿流体来源、成矿年代,探讨了二者之间的成因联系,查明拉么矿床成因。研究主要取得如下认识:(1)识别出脉状与层状矿体在金属矿物组合上的相似性。主要以黄铁矿、铁闪锌矿、黄铜矿、磁黄铁矿、毒砂及少量辉钼矿等为主。脉状矿石以角砾状构造、浸染状构造为主,层状矿石以块状构造、条带状构造为主。通过野外调查初步查清了地表蚀变类型主要有:矽卡岩化、硅化、大理岩化、电气石化、褐铁矿化。(2)拉么锌铜矿两类矿体中黄铁矿单矿物的稀土元素和微量元素组成特征相似,表明成矿流体来源与性质相似。结合前人流体包裹体及H-O同位素研究表明,其成矿流体主要来源于岩浆,并受到后期大气降水的混合,为形成于中—高温和较还原环境下的富Cl流体。同时二者在稀土和微量元素地球化学特征上与笼箱盖岩体较为相似,表明它们具有密切的成因联系。二者S、Pb同位素组成特征相似,表明二者成矿物质来源相似。成矿物质主要来源于地壳,并有幔源成分的加入,属于壳幔混合来源,表明成矿物质来源于壳幔混源的岩浆。(3)层状矿体和脉状矿体中辉钼矿模式年龄分别为91.36±1.47~93.27±1.53Ma和90.97±1.74Ma,其年龄基本一致,表明二者是同一成矿期的产物。二者等时线年龄为91.55±0.67,与笼箱盖黑云母花岗岩年龄91.63±0.28Ma接近,反映了矿体的形成与笼箱盖岩体的侵位具有密切的关系。(4)拉么锌铜矿床为泥盆系碳酸盐地层赋矿、岩体提供成矿物质以及成矿流体的典型岩浆-热液作用形成的矽卡岩型矿床,并建立深部贡献—垂向运移—侧向交代成矿的成矿模式。
[Abstract]:Lamo zinc copper deposit is an important deposit in Dachang Orefield in the middle section of Danchi metallogenic belt.On the basis of summing up and analyzing all aspects of previous researches on the deposit, through field geological investigation and various analytical and testing methods, this paper has carried out the geological characteristics of the Lemo deposit, the trace rare earth elements of single mineral rocks and pyrite.The geochemical characteristics of two types of orebodies, the source of ore-forming material, the source of ore-forming fluid and the metallogenic age are compared. The genetic relationship between them is discussed and the genesis of the Lemo deposit is found out.The main results of this study are as follows: (1) identifying the similarity of vein and stratiform ore bodies in metal mineral assemblages.Mainly pyrite, sphalerite, chalcopyrite, pyrrhotite, arsenopyrite and a small amount of molybdenum.Vein ore is breccia structure, disseminated structure is dominant, stratiform ore is block structure, stripe structure is dominant.Through field investigation, the main types of surface alteration are as follows: skarn, silicification, marble, electrical petrochemical, limonitization, etc.) the characteristics of the rare earth elements and trace elements of the pyrite single minerals in the two types of orebodies of Lamo zinc copper deposit are similar.It is shown that the source and properties of ore-forming fluids are similar.Combined with previous fluid inclusions and H-O isotopic studies, it is shown that the ore-forming fluids are mainly derived from magma and mixed by late atmospheric precipitation, which are Cl rich fluids formed in medium-high temperature and relatively reduced environments.At the same time, the geochemical characteristics of rare earth elements and trace elements are similar to those of the cage caprock, indicating that they are closely related to each other.The characteristics of the isotopic compositions of Pb and S _ 2O _ 2 are similar, indicating that the source of the ore-forming material is similar between them.The ore-forming materials are mainly derived from the crust, with the addition of mantle-derived elements, and belong to the crust-mantle mixed source.The results show that the molybdenum model ages of laminar orebodies and vein orebodies are 91.36 卤1.47, 93.27 卤1.53Ma and 90.97 卤1.74 Ma.The ages are basically the same, indicating that they are the products of the same metallogenic period.The isochron age is 91.55 卤0.67, which is close to the age of 91.63 卤0.28Ma of the cage cover biotite granite, which indicates that the formation of the orebody is closely related to the emplacement of the cagon-covered rock mass.The rock mass provides skarn type deposits formed by typical magma hydrothermal interaction of ore-forming fluids and establishes a metallogenic model of deep contribution vertical migration and lateral metasomatism.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.4

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