内蒙古额尔古纳地区七一牧场铅锌矿床成因与矿化富集规律

发布时间：2018-11-23 09:41

【摘要】：七一牧场铅锌矿床位于兴蒙造山带东段，塔源—喜桂图断裂北西侧的额尔古纳地块内。区内成矿地质条件优越，铅、锌、银等矿产资源丰富。本文在收集区域地质和矿区地质资料的基础上，通过野外地质调研及测试分析综合研究，并结合区内同类型矿床的对比，对七一牧场铅锌矿床的成矿地质背景、矿床地质特征、矿床成因和矿化富集规律开展研究。 七一牧场矿床赋存于上侏罗统塔木兰沟组火山岩地层中，矿化受NW向断裂和构造裂隙控制明显，，矿体多呈脉状和透镜状产出；矿石中金属矿物以闪锌矿、方铅矿、黄铜矿、黄铁矿等为主，并含有少量毒砂；金属矿物主要呈自形晶及他形晶粒状结构、交代残余结构、交代溶蚀结构、乳滴状固溶体分离结构等；矿体及围岩发育中低温热液蚀变，其中，硅化、黄铁矿化、萤石化与矿化关系最密切；矿床的成矿过程分为热液期（毒砂—黄铁矿、石英—多金属硫化物、石英—方解石阶段）和表生期。 流体包裹体显微测温结果表明，该矿床石英—多金属硫化物阶段的成矿流体为中低温（132~342℃）、低盐度（0.5~11.9%NaCl eqv）、低密度（0.70~0.98g/cm3）的CO2-H2O-NaCl流体体系，流体的沸腾作用是七一牧场铅锌矿床元素沉淀的重要机制；石英—方解石阶段的成矿流体为中低温（160~280℃）、低盐度（1.4~9.3%NaCleqv）、低密度（0.70~0.98g/cm3）的流体体系。 根据该矿床的成矿地质条件、矿化特征和成矿物理化学条件，结合赋矿火山岩和矿石的稀土元素、微量元素和同位素特征，综合判断七一牧场铅锌矿床的成矿物质来源于上地幔，并有壳源物质的混入；矿石和火山岩可能具有相同物质源区，是不同期次同源岩浆作用的产物。本文认为，七一牧场铅锌矿床属于赋存于中生代火山岩中与浅成—超浅成岩浆作用有关的中低温热液脉型矿床。 区域同类矿床综合对比分析表明，塔木兰沟组地层对该区的Pb、Zn、Ag等矿床的形成有利；区域性NE向断裂控制了赋矿地层和铅锌矿床的空间分布，NW向和NWW向次级断裂构造具明显导矿、容矿作用，特别是构造交汇部位矿体规模增大，是热液脉状多金属矿的有利成矿部位。 七一牧场矿床工业矿体在水平方向上呈透镜状产出，厚度、品位、产状均在矿体的中间部位达到最大；垂向上，浅部矿体较深部的工业价值高。矿区内北东向断裂及其次级北西向隐伏断裂构造是该区主要的控矿容矿构造，对成矿最为有利；中等程度的硅化形成的石英细脉是非常重要的找矿标志；在地表形成次生铁锰染和铁帽，为该矿区找矿的直接标志。
[Abstract]:The Qiyidao Pb-Zn deposit is located in the Erguna block in the north west of the Tayuan-Xiguitu fault in the eastern part of the Xingmeng orogenic belt. The ore-forming geological conditions in the area are superior, and lead, zinc, silver and other mineral resources are abundant. On the basis of collecting regional geology and geological data of mining area, through field geological investigation and test analysis, combined with the comparison of the same type of deposits in this area, the metallogenic geological background and geological characteristics of the Qiyizang Pb-Zn deposit are studied in this paper. The genesis of ore deposits and the regularity of mineralization enrichment are studied. The Qiyilangao deposit occurs in the volcanic strata of the Upper Jurassic Tamulangou formation. The mineralization is obviously controlled by the NW trending faults and structural fissures, and the orebodies are mostly vein-like and lenticular. Sphalerite, galena, chalcopyrite, pyrite and so on are the main minerals in the ore, with a small amount of arsenopyrite. The metallic minerals are mainly self-shaped and allotropic, metasomatic residual, metasomatic solution, emulsion droplet solid solution separation structure and so on. The hydrothermal alteration in the development of orebodies and surrounding rocks at low temperature is closely related to silicification, pyrite and fluorite mineralization. The ore-forming process of the deposit can be divided into hydrothermal period (arsenopyrite-pyrite, quartz-polymetallic sulfide), quartz-calcite stage and epigenetic stage. The microthermometric results of fluid inclusions indicate that the ore-forming fluids in the quartz-polymetallic sulphide stage of the deposit are of moderate and low temperature (132 ~ 342 鈩

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