山东省苍峄铁矿地球化学及成矿机制讨论

发布时间：2018-06-23 06:04

本文选题：BIF + 苍峄铁矿　；参考：《成都理工大学》2017年硕士论文

【摘要】：苍峄铁矿在大地构造上位于华北克拉通-鲁中隆起之南缘的尼山(白彦)凸起与临沂凸起(穹断)交汇部位,是鲁西成矿带最重要的BIF铁矿床之一。通过近几年的地质工作开展,本区成矿研究取得了重大进展。本文在收集地质资料和野外地质调查的基础上,综合前人研究成果,通过矿床地质特征和地球化学特征,探讨了铁矿物质来源、成矿构造环境以及成矿机制。主要的成果与认识如下:1、矿物主要赋存于泰山岩群山草峪组地层中,铁矿石主要产于磁铁石英岩。磁铁石英岩为自形—半自形粒状结构。Fe质与Si质相间分布构成矿石的条带状构造,铁矿的主要围岩是黑云变粒岩和斜长角闪岩及部分角闪片岩等。2、磁铁石英岩全铁平均含量为33.45%,主量元素主要由SiO2(平均约46.94%)、Fe2O3(平均约18.64%)、FeO(平均约23.57%)组成,富集大离子亲石元素Th、Ba、Rb、U;亏损高场强元素Ti、Zr、Nb。矿石的稀土元素含量总体较低,经过PAAS标准化处理后,苍峄地区磁铁石英岩的表现为:轻稀土元素相对亏损,重稀土元素相对富集。其中δEu范围为:1.35-1.67,平均值为1.52,Eu总体为正异常,但是不明显,δCe范围为:0.84-1.01,平均值为0.94,无明显Ce异常。3、苍峄地区铁建造的形成与海底热液活动作用相关度大,但是根据Eu异常值判断可知,距离火山中心较远。在海水运动的稳定期与在缺氧的环境下硅质与铁质相继沉积,继而形成条纹状-条带状构造,且在沉积的过程中,很少有陆源碎屑物质的加入。4、根据黑云变粒岩和斜长角闪岩投图显示,本区为受火山活动影响的岛弧环境。同时山草峪组黑云变粒岩的原岩为砂质、泥质岩为主,超基性岩、基性岩石相对较少,表明本区总体上构造环境相对活跃,形成环境处在碰撞拼合阶段。5、海底火山热液为主要的成矿物质来源,并且距离热液中心有一定距离,海底火山热液在海水的搬运下不断流失,但仍得到了一定的富集。经过较大规模的区域变质作用的改造下,使原有岩石发生重结晶作用,促进了铁质的进一步富集。后期岩系在强烈的褶皱作用改造和后期断裂作用对矿体的形成无决定性作用,但对产出产生重要影响,最终形成了以铁质和硅质为主要成分的BIF型铁矿。
[Abstract]:Cangyi Iron Mine is one of the most important BIF iron deposits in the western Shandong metallogenic belt, which is located at the junction of the Nishan (Baiyan) uplift and the Linyi uplift (Dome) in the southern margin of the North China Craton-Central Shandong uplift. Through geological work in recent years, great progress has been made in metallogenic research in this area. On the basis of collecting geological data and field geological survey and synthesizing the previous research results, through geological and geochemical characteristics of ore deposit, the source of iron ore, metallogenic tectonic environment and metallogenic mechanism are discussed in this paper. The main achievements and understandings are as follows: 1. Minerals mainly occur in the Caoyu formation of Mount Taishan Group and iron ore mainly occurs in magnetite quartzite. The magnetite quartzite is a zonal structure formed by the distribution of Fe and Si phases. The main surrounding rock of iron ore is black cloud granulite, amphibolite and partial hornblende schist, etc. The average total iron content of magnetite quartzite is 33.455.The main elements are mainly composed of Sio _ 2 (average 46.94%), Fe _ 2O _ 3 (average 18.64%) and Fe _ 2O _ 3 (mean about 23.57%). The heavy ion lipophilic element Th _ (+) Ba _ (+) RbN _ (U) is enriched, and the high field strength element Ti ~ (2 +) Zr ~ (2 +) Nb. The content of rare earth elements in ore is generally low. After PaaS standardization, the magnetite quartzite in Cang area is characterized by the relative depletion of light rare earth elements and the relative enrichment of heavy rare earth elements. The 未 EU range is 1.35-1.67, the average value is 1.52 EU positive anomaly, but it is not obvious. The 未 ce range is 0.84 to 1.01and the average value is 0.94. There is no obvious ce anomaly .3.The formation of iron formation in Cangyi area has a strong correlation with submarine hydrothermal activity. But according to the EU outliers, it is far from the center of the volcano. In the stable period of sea water movement and in anoxic environment, siliceous and iron deposits are successively formed, and then striate stripe structure is formed, and in the process of deposition, Few land-based clastic materials are added. According to the maps of black cloud granulite and amphibolite the area is an island arc environment affected by volcanic activity. At the same time, the primary rocks of the black cloud granulites of the Shancaoyu formation are sandy, mainly argillaceous, ultrabasic and relatively few, indicating that the tectonic environment in this area is relatively active in general. The forming environment is at the stage of collision and assembly. The submarine volcanic hydrothermal solution is the main source of ore-forming material and is far from the hydrothermal center. The submarine volcanic hydrothermal fluid is continuously lost under the transport of sea water, but it is still enriched to a certain extent. After the transformation of large scale regional metamorphism, the original rocks are recrystallized, which promotes the further enrichment of iron. The late rock series were not decisive in the formation of orebodies due to strong fold transformation and late fracture, but had an important effect on the formation of ore bodies. Finally, BIF iron ores with iron and siliceous composition as the main components were formed.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.31

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