胶东上庄金矿地质特征与黄铁矿微区成分结构研究

发布时间：2018-03-24 02:28

本文选题：上庄金矿　切入点：望儿山断裂　出处：《中国地质大学(北京)》2015年硕士论文

【摘要】：上庄矿区是胶东蚕庄金矿的主要矿区,处于焦家金矿田东南缘。在区域地质及矿床地质背景方面与焦家金矿田各矿床相似,但也有其独特之处。主要包括:(1)矿区位于焦家断裂带的次级断裂—望儿山断裂上,矿体严格受望儿山断裂构造多期变形控制;(2)恰好位于莱州-招远整装勘查区的两大岩体,即玲珑岩体和郭家岭岩体接触带上;(3)虽然上庄矿区也为构造控矿,但是其矿体主要分布于望儿山断裂上盘,而著名的焦家金矿田矿体多位于断层下盘;(4)焦家矿体多数金矿控矿构造的上盘和下盘在岩相上差别较大,而上庄矿区的望儿山断裂其上下盘岩相上相同或相似;(5)围岩蚀变以硅化为主。本文结合高分辨率扫描电镜和透射电镜,对胶东上庄矿区主成矿期及成矿期后过程进行探讨,着重开展了黄铁矿演化期次、演化特征、金的赋存状态以及微量稀土元素赋存状态的研究。取得了如下一些认识:(1)焦家金矿田少有毒砂与金共生关系报道,但在上庄矿区发现金与毒砂关系密切,许多矿石中银金矿普遍分布于毒砂与黄铁矿接触带上;(2)上庄矿区矿石中Bi富集程度异常高,通过详细的微区分析发现是因为黄铁矿包裹或共生大量的碲铋矿;(3)一些稀土元素含量的异常,是因为黄铁矿中包裹有独居石矿物颗粒,故上庄矿区在进行微量元素和稀土元素测试时,应将微区分析与湿化学方法结合。上庄金矿成矿过程中黄铁矿及金的演化规律如下:初始黄铁矿在成矿流体中结晶较快,形成颗粒粒径小(一般小于20μm),特征晶型为八面体、五角十二面体及其聚晶的黄铁矿,部分元素Au随着黄铁矿快速结晶成为不可见金;后期黄铁矿经历了较强的热液或变质作用,黄铁矿发生动态重结晶,颗粒形成港湾状、锯齿状特征的边界,该阶段黄铁矿颗粒粒径较大(多为300~500μm);热液或变质作用使得黄铁矿中的不可见金逐渐往外迁移;在高温主导阶段,黄铁矿边界趋向达到重新平衡,通过静态重结晶作用形成“退火”结构,即互成120°的三节点边界,重结晶恢复过程使黄铁矿颗粒变小,粒径多在50~100μm;随着温度降低,黄铁矿晶内裂隙和穿晶裂隙大量发育,为可见金的聚集提供了有利环境。
[Abstract]:Shangzhuang ore area is the main ore area of Jiaojia gold deposit, which is located in the southeast margin of Jiaojia gold field. The regional geology and geological background of the deposit are similar to those of each deposit in Jiaojia gold ore field. But it also has its own uniqueness. It mainly includes: the mining area is located on the secondary fault-Wangershan fault in the Jiaojia fault zone, and the orebody is strictly controlled by the multi-stage deformation of the Wangershan fault structure. The orebody is located in the two major rock masses in the Laizhou-Zhaoyuan integrated exploration area. Although the Shangzhuang ore area is also controlled by tectonics, the orebody is mainly distributed in the upper plate of Wangershan fault. However, the ore bodies of the famous Jiaojia gold ore field are mostly located at the lower side of the fault, and the upper and lower faces of most gold ore control structures of the Jiaojia ore body are quite different in lithofacies. But in Wangershan fault of Shangzhuang mining area, the alteration of surrounding rock is mainly silicification in the same or similar lithofacies of upper and lower face. Combining with high resolution scanning electron microscope and transmission electron microscope, the main metallogenic stage and post-metallogenic process of Shangzhuang ore area in Jiaodong are discussed in this paper. This paper focuses on the study of the stages, characteristics, occurrence of gold and the occurrence of trace rare earth elements of pyrite. Some understandings are obtained as follows: there are few reports on the symbiotic relationship between arsenopyrite and gold in Jiaojia gold ore field. However, in Shangzhuang ore area, the relation between cash and arsenopyrite is close, and the silver gold deposits in many ores are generally distributed in the contact zone of arsenopyrite and pyrite. Through detailed microanalysis, it is found that the anomalies of some rare earth elements are due to pyrite enclosing or symbiotic large amounts of tellurium bismuth), and because there are monazite mineral particles in pyrite. Therefore, microanalysis and wet chemical methods should be combined in the testing of trace elements and rare earth elements in Shangzhuang mine. The evolution of pyrite and gold in the metallogenic process of Shangzhuang gold deposit is as follows: the initial pyrite crystallizes rapidly in the ore-forming fluid. The formation of pyrite with small particle size (generally less than 20 渭 m), characterized by octahedron, pentagonal dodecahedron and polycrystalline pyrite, in which some elements au became invisible with the rapid crystallization of pyrite, and pyrite experienced strong hydrothermal or metamorphism in the late stage. Dynamic recrystallization occurs in pyrite, and the particles form the boundary of bays and serrated features. In this stage, the size of pyrite particles is larger (mostly 300 ~ 500 渭 m); hydrothermal or metamorphism makes the invisible gold in pyrite gradually migrate outward; at the stage of high temperature, The boundary of pyrite tends to rebalance. Through static recrystallization, a "annealing" structure is formed, that is, a three-node boundary of 120 掳. During the recrystallization recovery process, the pyrite particles become smaller, and the particle size is more than 50 ~ 100 渭 m, with the decrease of temperature. The large number of cracks and transgranular cracks in pyrite provide a favorable environment for the accumulation of visible gold.
【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】：P618.51

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