吉林和龙官地铁矿矿床地质特征及矿化富集规律

发布时间：2018-03-02 13:17

本文选题：BIF　切入点：矿床地质　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：官地铁矿床位于吉林省和龙市境内,其大地构造位置属于华北地台北缘东段,胶辽吉活动带以北的龙岗地块西北边缘。位于和龙太古代铁成矿带,是延边重要的铁矿带。矿区地层出露简单,主要是太古界三道沟组的中段和上,段(原百日坪组和甲山组),矿区内构造以断裂和褶皱构造为主,其中北西向构造主要为褶皱和层间破碎带,北东向构造以蜂蜜沟断裂规模最大,主要控制热液活动和闪长岩脉侵入,对矿体破坏较大。矿区内岩浆活动表现的岩石种类简单,主要为闪长岩脉。官地铁矿主要产在太古界三道沟组上段(原甲山组)下部层位,一套深变质的基性-酸性火山-沉积建造中。受构造作用影响断续产出15个铁矿体群,以Ⅰ、Ⅱ、Ⅳ、Ⅴ、Ⅵ、Ⅶ、Ⅷ、Ⅹ、Ⅶ号矿组矿体规模相对较大,构成工业矿体。矿体主要呈层状、似层状、扁豆状。矿石类型比较简单,为磁铁石英岩,由硅质和铁质条带互层构成,矿石构造以条带状和浸染状构造为主。矿体的围岩主要为斜长角闪岩和长英质片麻岩,经原岩恢复分别为拉斑玄武岩和酸性喷出岩,产出与岛弧构造背景中。其中对斜长角闪岩进行了锆石U-Pb年代学研究,结果可分为三组:第一组年龄为2724±22Ma,为捕获锆石的年龄,代表区域内存在～2.7Ga的岩浆事件;第二组锆石全部为岩浆锆石,环带清晰,年龄2556±17Ma,代表斜长角闪岩原岩形成的年龄;第三组锆石可见清晰的核幔结构,围绕核部岩浆锆石形成色调较浅的变质增生边,为典型的变质锆石,207Pb/206Pb加权平均年龄为2452±23Ma,代表该时期内发生变质事件。对BIF的年代学研究往往采用对其上下盘及夹层围岩进行年龄测定的方法,间接得到成矿时代。因此官地铁矿的时代应为2556±17Ma。通过对矿石的地球化学研究,发现矿石形成于缺氧的海水环境中,很少有陆源碎屑物质的加入。其成矿物质来源中铁质主要来自与海底火山相关得海底高温热水的喷流作用,Si质同样来源于高温的热水体系中。Fe质主要以Fe2+的形式搬运,其沉淀机制在太古代的缺氧环境中可能与微生物的活动,密切相关。原始沉积的硅铁条带形成后,后期的变质和变形作用,是成矿物质发生活化和迁移,改造成了硅铁条带,Si质和Fe质重结晶形成石英和磁铁矿颗粒,使矿体达到富集。通过研究,认为官地铁矿成矿年龄为～2.5Ga,形成于与洋壳俯冲有关的岛弧环境中,～2.45Ga发生弧陆碰撞、弧弧碰撞使区域内岩石普遍遭受变质作用,使先前沉积形成的矿体遭受改造。通过与国内典型的BIF铁矿的对比,认为官地铁矿为与火山活动关系密切的Algoma型BIF铁矿。通过矿化富集规律的研究,官地BIF铁矿的形成与太古代的表壳岩密切相关。与古老的表壳岩同期形成并作为矿体的直接赋矿围岩。古老的表壳岩是寻找BIF型铁矿床的重要标志和必备条件。后期的断裂构造使矿体发生错段,破坏了矿体的连续性,断裂构造还为热液的运移提供了通道,但热液作用对官地铁矿的改造作用并不明显。褶皱构造有利于矿层的加厚,在平面和剖面上,褶皱转折端往往发生加厚富集。
[Abstract]:The deposit is located in the territory of the subway, Helong City, Jilin Province, and its tectonic position belongs to North China Taipei border east, Jiao Liao Ji belt to the northwest edge of Longgang block north. Located in the Helong Archaean iron metallogenic belt, Yanbian is an important iron ore belt. The stratum of mining area is simple, mainly Archean three ditch group the middle section and, (the original hundred days Ping group and kapsan group), within the mining area structure to fracture and fold structure, which is mainly NW folds and interlayer fracture zone, NE structure with honey ditch largest fault, the main control of hydrothermal activity and diorite vein invasion on the great damage. Magmatic activity within the mining area is the main rock types, diorite dikes. Iron ore is mainly produced in the Guandi Archean three channel formation (formerly Jiashan group) of lower strata, a base of deep metamorphic acidic volcano sedimentary formations by tectonism. Influence of intermittent output of 15 iron ore body group, with I, II, IV, V, VI, VII, VIII, x, VII ore group ore scale is relatively large, form industrial ore bodies. The ore body mainly is layered, stratoid, lenticular. The ore type is relatively simple, for magnetite quartzite, made of silica and iron with each layer, ore structure in banded and disseminated structures are the main ore body. The surrounding rock is mainly amphibolite and felsic gneiss, the protolith were tholeiite and acidic volcanic rocks, output and arc tectonic background. The amphibolite of zircon U-Pb chronology research results can be divided into three groups: the first group age was 2724 + 22Ma, to capture the zircon age, there are ~ 2.7Ga magmatic events represent region; second groups of zircon all magmatic zircon, zoning clear, age 2556 + 17Ma, on behalf of amphibolites formed third groups of age; The core mantle structure zircon is clearly visible, around the core of magmatic zircon formation of metamorphic zircons tone shallow edge, is typical of metamorphic zircons, 207Pb/206Pb weighted average age was 2452 + 23Ma, on behalf of the metamorphic event occurred period. Dating of the BIF method is used for the determination of the age on the footwall and laminated rock therefore, indirect metallogenic epoch. The age of the iron crown was 2556 + 17Ma. by geochemistry of ore, ore formation found in anoxic seawater environment, there is little terrigenous material. Adding its exhalation ore-forming material sources of iron mainly from submarine volcano related to submarine hot water, Si also comes from the hot water system in.Fe matter is mainly in the form of Fe2+ handling, its precipitation mechanism may in anoxic environment in the Archean closely with microbial activity. The original deposition of ferrosilicon bands formed after the late metamorphism and deformation, and the migration of ore-forming materials made into life, ferrosilicon bands, Si and Fe heavy crystallization of quartz and magnetite particles, the ore enrichment is obtained. Through the research, that the metallogenic age of iron ore for the officer to 2.5Ga formation related to subduction of oceanic crust and island arc environment, to the occurrence of 2.45Ga arc continent collision, arc arc collision in the region suffered from rock metamorphism, ore deposit formation make previously suffered transformation. By comparing with the domestic typical BIF of iron ore, iron ore as that officer and volcano activity type Algoma BIF iron ore closely. Through the study of mineralization enrichment regularity, formation of the official BIF iron ore is closely related with the supracrustal rocks of Archean supracrustal rocks. And the ancient period and formed as the wall rocks of the ore bodies. The old supracrustal rocks is looking for BIF type And the essential condition of an important symbol of deposits. The late faults caused the occurrence of fault section, fractured orebody, fracture structure also provides a channel for the migration of hydrothermal fluid, but hydrothermal alteration of Guandi iron ore is not obvious. Fold to add thick seam, on the plane and profile on the turn end of fold often thickened enrichment.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.31

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