内蒙古边家大院铅锌多金属矿矿床地质特征、地球化学特征及成矿模式

发布时间：2018-04-06 23:15

本文选题：岩石地球化学　切入点：闪锌矿微量元素　出处：《中国地质大学(北京)》2017年硕士论文

【摘要】：内蒙古林西县边家大院铅锌多金属矿床是大兴安岭中南段近年来新发现的矿床,其中Pb、Zn、Ag、Sn均达到中型规模,另外还有大量伴生金属矿产。共发育有三种类型的矿床:斑岩型Sn-Mo-Cu矿床,隐爆角砾岩型Pb-Zn-Ag矿床,次火山热液脉型Pb-Zn-Ag矿床。矿体严格受构造控制,斑岩型Sn-Mo-Cu矿床产在研究区石英斑岩体内部,隐爆角砾岩型Pb-Zn-Ag矿床产在隐爆角砾岩筒内部,次火山热液脉型Pb-Zn-Ag矿床产在二叠系哲斯组地层和辉石闪长岩构造裂隙中。前人在本区做了很多工作,本文在前人的研究工作基础上,进行岩石地球化学特征、矿石地球化学特征、成矿流体特征研究,并探讨成矿体系,初步建立成矿模式。1)研究区新发现的二长花岗岩和石英斑岩的地球化学特征极为相似,主量元素研究表明二者具有高钾钙碱性过铝质特征,属于具有S型花岗岩特征的A型花岗岩,与区内Sn矿形成关系密切;微量元素研究指示二长花岗岩和石英斑岩为陆缘隆起带陆壳重熔型岩浆成因。辉石闪长岩为高钾钙碱性过铝质侵入岩,微量元素特征表明,辉石闪长岩具有俯冲带特征,岩浆形成与俯冲作用关系密切。2)研究区矿石地球化学特征研究表明边家大院铅锌多金属矿床属于中温岩浆热液型矿床,成矿流体具有富C1的特点;稀土元素研究指示成矿过程中有海水的加入,且成矿热液所经历的氧化还原环境发生了变化。3)对西区石英和方解石中的包裹体镜下观察发现,主要有富气相(G型)和富液相(L型)两种类型,以富液相包裹体为主。成矿流体显示了中等温度、中等盐度、中低密度的特点,成矿压力较低,成矿深度属于中浅成。东区成矿流体盐度、密度、压力和深度较西区稍低,显示出岩浆自西向东的侵入路径。4)边家大院铅锌银锡多金属矿床形成的直接因素可以总结为“三个体系”,分别是俯冲成因的岩浆体系、多期次构造体系和含矿热液流体体系。岩浆体系是矿床形成的物质来源及热源中心,构造体系为成矿提供了导矿和容矿空间,含矿热液流体体系为成矿物质的迁移就位提供条件。
[Abstract]:The Pb-Zn polymetallic deposit in Bianjiayuan, Linxi County, Inner Mongolia, is a newly discovered deposit in the central and southern part of the Daxing'anling Mountains in recent years.There are three types of deposits: porphyry type Sn-Mo-Cu deposit, crypto-explosive breccia type Pb-Zn-Ag deposit, subvolcanic hydrothermal vein type Pb-Zn-Ag deposit.The orebody is strictly controlled by structure. The porphyry type Sn-Mo-Cu deposit occurs in the quartz porphyry body in the study area, and the crypto-explosive breccia type Pb-Zn-Ag deposit occurs in the crypto-explosive breccia tube.The subvolcanic hydrothermal vein type Pb-Zn-Ag deposit occurs in the Permian Zhesi formation and pyroxene diorite structural fractures.Many works have been done in this area. On the basis of previous research work, this paper studies the characteristics of rock geochemistry, ore geochemistry, ore-forming fluid, and discusses the ore-forming system.The geochemical characteristics of the newly discovered monzogranites and quartz porphyry in the study area are very similar, and the principal element studies show that they have the characteristics of high potassium calc-alkaline peraluminous.It belongs to the A-type granite with the characteristics of S-type granite, which is closely related to the formation of Sn ore in the area, and the trace element study indicates that the bifeldite and quartz porphyry are of continental crust-remelting magma origin in the continental margin uplift zone.The pyroxene diorite is a high-potassium calc-alkaline peraluminous intrusive rock. The trace element characteristics indicate that the pyroxene diorite is subducted.The ore geochemical characteristics of the study area indicate that the lead-zinc polymetallic deposit in Bian Jia Yuan belongs to the medium-temperature magmatic hydrothermal deposit and the ore-forming fluid has the characteristics of rich in C _ 1;The study of rare earth elements indicates that seawater is added into the ore-forming process, and the redox environment experienced by the ore-forming hydrothermal solution has changed .3) the inclusion in quartz and calcite in the western region is observed under microscope.There are two main types: G type rich in gas phase and L type rich in liquid phase, mainly rich in liquid inclusions.The ore-forming fluid shows the characteristics of medium temperature, middle salinity and low density, and the ore-forming pressure is low, and the ore-forming depth belongs to medium and shallow mineralization.The salinity, density, pressure and depth of the ore-forming fluids in the eastern region are slightly lower than those in the western region, indicating that the direct factors for the formation of the lead-zinc-silver-tin polymetallic deposits from the west to the east show that the magma invades from the west to the east. The direct factors of the formation can be summed up as "three systems".They are subducted magmatic system, multi-stage tectonic system and ore-bearing hydrothermal fluid system.The magmatic system is the material source and heat source center of the deposit formation. The tectonic system provides the ore-conducting and ore-containing space, and the ore-bearing hydrothermal fluid system provides the conditions for the migration and placement of the ore-forming material.
【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】：P618.2

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