北京市密云县桑园铁矿地质特征及成矿规律

发布时间：2018-06-03 22:14

本文选题：密云县 + BIF型铁矿床　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：桑园铁矿床属于华北地台重要的铁矿集区之一—冀东—密怀矿集区,矿床成因类型为火山—沉积变质型(BIF)矿床。本文通过野外地质调查、钻探施工和室内岩相学、矿相学研究,深入阐述了桑园铁矿的地质特征,在此基础上,结合前人的相关研究成果,总结了矿床的成矿规律,建立了矿床成矿模式,并结合地面磁测及井中物探的资料,对矿区深部及周边进行成矿预测。主要取得了以下认识:1、桑园铁矿赋存于太古宇密云群大漕组,矿区出露的岩性主要为黑云斜长片麻岩、黑云辉石斜长片麻岩、石榴辉石斜长片麻岩、黑云二长片麻岩及磁铁石英岩。矿区构造发育较弱,多为一些局部小褶皱和小断层,它们对矿体的形态和分布具有一定的影响。矿体呈似层状、透镜状,北东向展布,变化较稳定。矿石主要为磁铁石英岩,具粒状变晶结构,条带状构造或片麻状构造。矿床整体上位于高岭-西恒河大型复式向斜的东南翼,其空间分布受该复式向斜控制。2、矿层产状与围岩一致,其空间分布受地层层位控制。矿床形成时代为中太古代,成矿年龄大于2800Ma,矿床经历了角闪岩相—麻粒岩相的区域变质作用的改造。矿层顶、底板围岩普遍发育石榴石化,深红色的石榴子石富集成明显的条带状,可作为钻探工程预见矿或过矿的参考标志。3、桑园铁矿的成因类型为火山—沉积变质型,成矿环境为远离火山活动中心的相对稳定的海盆环境,成矿物质来源于海底火山活动。矿床的成矿模式为:海底火山活动喷出的富含铁质和硅质的热液,在上升性洋流作用下运移到浅部,Fe2+被氧化沉淀形成铁质层,而海水化学平衡的改变导致硅质的沉淀形成硅质层。矿石条带状构造的形成可能与周期性的上升流有关,而海底火山活动的多旋回性造成矿体具有多层性。4、地面磁测的成果显示,桑园铁矿区东南侧磁异常明显,预测该区具有较大的找矿潜力。井中磁测的结果,以ZK170-1钻孔为例,△Z曲线负张口,△T'曲线正张口,△H⊥与△H//矢量向线簇较短,反映矿区深部的找矿潜力不大。
[Abstract]:The Sangyuan iron deposit belongs to one of the important iron ore accumulation areas of the North China platform Jidong Mihuai ore accumulation area. The genetic type of the deposit is the volcanic sedimentary metamorphic type BIF-deposit. Based on field geological investigation, drilling construction, laboratory petrography and mineralogy, the geological characteristics of Sangyuan Iron Mine are expounded in depth. On the basis of this, the metallogenic regularity of the deposit is summarized in combination with the related research results of predecessors. The metallogenic model of the ore deposit is established, and the metallogenic prediction is carried out on the deep and periphery of the ore area with the data of surface magnetic survey and geophysical exploration in the well. We have obtained the following understanding: Sangyuan Iron Mine is located in the Dacao formation of Miyun Group, Taigu. The lithology of the ore area is mainly composed of black cloud plagioclase gneiss, black cloud pyroxene obliquity gneiss, pomegranate plagioclase gneiss, and garnet gabbro plagioclase gneiss. Black cloud gneiss and magnetite quartzite. The structure of the mining area is relatively weak, most of them are local small folds and small faults, which have certain influence on the shape and distribution of orebody. The orebody is layered, lenticular, and distributes from north to east, and its variation is stable. The ore is mainly magnetite quartzite, with granular metamorphic structure, stripe-like structure or sheet-like structure. As a whole, the deposit is located in the southeast wing of the large complex syncline of Kaoling-Xihang River. The spatial distribution of the deposit is controlled by the complex syncline. The occurrence of ore bed is consistent with that of surrounding rock, and its spatial distribution is controlled by the stratigraphic position. The ore deposit was formed in the Middle Archean with a metallogenic age of more than 2800Ma.The deposit underwent the transformation of regional metamorphism of amphibolite facies and granulite facies. Pomegranate fossilization is widely developed in the surrounding rock of the top and bottom of the ore bed, and the Shi Fu of the crimson pomegranate has obvious strip shape, which can be used as the reference mark of the drilling engineering to foresee the ore or go through the ore. The origin type of the Sangyuan iron deposit is volcanic-sedimentary metamorphic type. The ore-forming environment is a relatively stable oceanic environment far from the center of volcanic activity, and the ore-forming material originates from submarine volcanic activity. The ore-forming model of the deposit is as follows: hydrothermal fluid, rich in iron and siliceous, spewed from undersea volcanic activity, transported to the shallow part of Fe _ 2 to be oxidized and precipitated to form an iron layer under the action of rising ocean currents. The change of the chemical equilibrium of seawater results in the formation of siliceous layer. The formation of ore stripe structure may be related to the periodic upwelling, and the polycycle of submarine volcanic activity causes the orebody to have multilayer. 4. The results of surface magnetic survey show that the southeast side of Sangyuan Iron Mine is obviously abnormal. It is predicted that this area has great prospecting potential. Taking ZK170-1 borehole as an example, the results of magnetic logging in wells show that Z curve is negative, T 'curve is positive, H ~ (-) and H _ (-) / vector linear cluster is short, which shows that the prospecting potential in deep mining area is not great.
【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】：2015
【分类号】：P618.31

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