云南武定迤纳厂矿床主要矿物地球化学特征及矿床成因探讨

发布时间：2018-09-06 19:31

【摘要】：迤纳厂矿床是康滇地轴典型的铁—铜—稀土矿床之一。因为其特殊的矿物组合(磁铁矿与黄铜矿共生)以及富含稀土矿物,该矿床一直是矿床学家研究的热点。本论文以滇中地区武定迤纳厂铁—铜—稀土矿床为研究对象,通过野外调研、室内分析测试、用各种地球化学手段综合研究,总结矿物组合特征,对变质围岩进行原岩恢复,研究金属矿物、非金属矿物的微量元素、稀土元素地球化学特征和元素组合特征,以及方解石C、O同位素特征和黄铜矿S同位素特征,总结成矿物质、成矿流体来源,对矿床成因进行了探讨。结果表明:(1)矿物组合特征表明,迤纳厂矿床金属矿物与非金属矿物之间存在着密不可分的关系。磁铁矿、黄铜矿大都为共生关系,与方解石、萤石、钠长石等非金属矿物也存在着共生关系。(2)变质原岩恢复结果:迤纳厂矿床变质围岩主要为大陆岛弧环境下形成的沉积岩(泥页岩、石英砂岩为主)。(3)磁铁矿和黄铁矿元素地球化学特征表明,成矿物质不是单纯的岩浆来源,而是多种来源,局部可能为沉积来源,说明可能为沉积改造成因,表明迤纳厂矿床成矿流体不是单一来源,早期岩浆成因,并有后期变质热液叠加作用成矿。(4)Y/Ho-La/Ho图解显示,迤纳厂矿床不同产状的萤石,流体可能为同一流体体系不同阶段的产物;三期方解石具有比较集中的La/Ho和Y/Ho值,指示它们可能形成于某一成矿阶段的相同成矿流体。萤石、方解石均主要为热液成因。对钠长石稀土元素地球化学研究表明,钠长石为热水及热液流体形成,为热液成因钠长石。由共生组合关系可得,成矿金属矿物与萤石、方解石、钠长石关系十分密切,因此,迤纳厂矿床属于典型的热液成因矿床。地幔流体对成矿具有重要意义。(5)通过对迤纳厂矿床方解石的C、O同位素分析,得出方解石中碳可能大部分由深源碳提供,并受到大气降水的影响以及沉积岩混染效应影响,部分方解石成矿流体中的碳来自于海相碳酸盐岩的溶解作用,表明迤纳厂矿床成矿热液和深部岩浆流体有很密切的关系,存在深部岩浆水、大气降水的混合作用。对黄铜矿硫同位素的分析,表明迤纳厂矿床具有IOCG矿床的特征,成矿流体来源与地幔流体紧密相关,并且与浅部地壳流体和成矿物质的混入有关。(6)通过共生组合关系,初步判断Fe和Cu为同期成矿元素,U和REE为同期成矿元素。主要成矿期是1.6~1.7Ga左右,与昆阳裂谷的拉张及Columbia超级大陆裂解关系密切,主要形成铁和铜;第二次成矿是0.7~0.8Ga左右,主要表现为铀和稀土的富集。
[Abstract]:Yinachang deposit is one of the typical iron-copper-rare earth deposits in the Kangdian axis. Because of its special mineral assemblage (magnetite and chalcopyrite symbiosis) and rich in rare earth minerals, the deposit has been a hot spot of ore deposit research. In this paper, taking the Wuding Yichang Fe-Cu rare earth deposit in central Yunnan as the research object, through field investigation, laboratory analysis and test, and comprehensive study of various geochemical means, the characteristics of mineral assemblage are summarized, and the original rock restoration of metamorphic surrounding rock is carried out. The trace elements, REE geochemical characteristics and elemental assemblage characteristics of metallic and nonmetallic minerals, as well as the characteristics of calcite Con O isotope and chalcopyrite S isotope, are studied, and the ore-forming materials and ore-forming fluid sources are summarized. The genesis of the deposit is discussed. The results show that: (1) the characteristics of mineral assemblage indicate that there is a close relationship between metallic minerals and non-metallic minerals in Yinnachang deposit. Magnetite, chalcopyrite are mostly symbiotic, with calcite, fluorite, There is also a symbiotic relationship between albite and other nonmetallic minerals. (2) the recovery of metamorphic primitive rocks: the metamorphic rocks of Yichang deposit are mainly sedimentary rocks (shale, mud shale) formed in the continental island arc environment. The geochemical characteristics of magnetite and pyrite elements in quartz sandstone (). (_ 3) indicate that the ore-forming material is not a simple magma source, but a variety of sources, and the local source may be a sedimentary source, which indicates that the ore-forming material may be a sedimentary alteration origin. The results show that the ore-forming fluid of Yinachang deposit is not a single source, the early magma genesis, and the late metamorphic hydrothermal superposition of ore-forming. (4) the Y/Ho-La/Ho diagram shows that the fluid may be the product of different stages of the same fluid system in different forms of fluorite in Nayinachang deposit; The third stage calcite has a relatively concentrated La/Ho and Y/Ho values indicating that they may form the same ore-forming fluid in a certain metallogenic stage. Fluorite, calcite are mainly hydrothermal origin. The geochemical study of rare earth elements in albite shows that albite is formed by hot water and hydrothermal fluid, and is hydrothermal albite. The metallogenic metal minerals are closely related to fluorite, calcite and albite. Therefore, Yinachang deposit is a typical hydrothermal deposit. Mantle fluid plays an important role in mineralization. (5) based on the Cno isotopic analysis of calcite in Yicheng Nachang deposit, it is concluded that most of the carbon in calcite is supplied by deep source carbon, which is influenced by precipitation and the mixed effect of sedimentary rocks. Some of the carbon in the calcite ore-forming fluid is derived from the dissolution of marine carbonate rocks, which indicates that the ore-forming hydrothermal fluid of Yinachang deposit is closely related to the deep magmatic fluid, and there is a mixture of deep magmatic water and atmospheric precipitation. The analysis of sulfur isotopes of chalcopyrite shows that the Yinachang deposit has the characteristics of IOCG deposit, the source of ore-forming fluid is closely related to mantle fluid, and it is related to the mixing of shallow crustal fluid and ore-forming material. (6) through symbiotic assemblage, It is preliminarily determined that Fe and Cu are synchronic ore-forming elements, U and REE are synchronic ore-forming elements. The main metallogenic period is about 1.6~1.7Ga, which is closely related to the extension of Kunyang rift and the splitting of Columbia supercontinent, which mainly forms iron and copper, and the second metallogenic stage is about 0.7~0.8Ga, which mainly shows the enrichment of uranium and rare earth.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.31;P618.41;P618.7

【参考文献】