青海德尔尼铜多金属矿床成因及找矿方向

发布时间：2018-02-05 23:46

本文关键词： 德尔尼铜矿海底喷流沉积矿床成因找矿方向　出处：《中国地质大学(北京)》2016年硕士论文　论文类型：学位论文

【摘要】：德尔尼铜矿位于青海省布青山—积石山铜多金属成矿带上,属阿尼玛卿晚古生代造山带东段,由于该成矿带经历了前寒武纪不同地块构造基底的复杂演化以及强烈构造运动,形成了广泛分布矿区的蛇绿混杂岩带,再加上后期造山运动的叠加与各种沉积建造等的组合,最终形成了多金属矿化带。自该矿床发现以来,关于其成因的争论一直存在争议,各种原因有各自的证据,如深部熔离矿床、花岗岩热液矿床以及海底热液矿床等。因此,对于该矿床的成因研究具有较重要的意义,这也有助于为以后的找矿工作有一定的指导意义。所以,本文通过电子显微镜镜下观察和电子探针及矿物年龄等实验研究,探讨了矿床的成因,为矿床以后的开采工作提供了一定的指向。通过野外观察及矿相学研究,大致将德尔尼铜矿床中主要矿石矿物成矿期次进行了总结,认为最主要矿石矿物黄铁矿分为三期,黄铜矿、闪锌矿分为两期,磁黄铁矿、磁铁矿共有一期。根据电子探针数据,得出矿体中黄铁矿、黄铜矿、闪锌矿等主要矿物产生于中低温热液环境下。岩石地球化学特征分析得出,斜长角闪岩为一套基性-超基性岩为主的组合,其主要岩石类型有安山岩、玄武岩、苦橄岩等,具低钾偏铝质钙碱性特征。稀土元素方面呈轻稀土富集,重稀土亏损的特征,具有微弱的铕正异常;岩石中大离子亲石元素Rb、Ba、Sr等元素明显富集,高场强元素Nb、Ta、U相对亏损,而Pb、Zr等元素与原始地幔相当或略有富集。研究区锆石U-Pb年代学研究表明,其成矿时间为310.0±4.7Ma,属于晚石炭世。经过研究,初步认为德尔尼铜多金属矿床是以海底喷流—沉积成矿为主体,以后期叠加成矿为特色的复合成矿作用的矿床,归纳为成矿热液沿裂隙喷出和沉积,矿体顶部存在一套含碳铁硅质板岩,超基性岩在后期构造作用影响下对主矿体挤压变形,在接触部位影响了钴矿及磁黄铁矿等叠加成矿的过程,矿床在随后的叠加成矿过程中经历了多种形式的构造破坏和位置的变动,并且在此基础上提出了德尔尼矿床的找矿标志,即:褶皱构造转折端、构造角砾岩带、超基性岩体片理化带、超基性岩体与围岩接触带、逆冲推覆构造下盘、超基性岩构造透镜体。
[Abstract]:Delney copper deposit is located in the Buqingshan-Jishi mountain copper polymetallic metallogenic belt in Qinghai Province, which belongs to the eastern section of the late Paleozoic orogenic belt. Due to the complex evolution of the tectonic basement of different Precambrian blocks and the strong tectonic movement, the metallogenic belt formed a widely distributed ophiolite melange belt. Combined with the combination of late orogeny and various sedimentary formations, the polymetallic mineralization zone was formed. Since the discovery of the deposit, there has been controversy about its genesis. All kinds of reasons have their own evidences, such as deep melt deposit, granite hydrothermal deposit and submarine hydrothermal deposit, etc. Therefore, it is of great significance to study the genesis of the deposit. Therefore, through the observation of electron microscope and the experimental study of electron probe and mineral age, the origin of ore deposit is discussed in this paper. Through field observation and mineralogical study, the metallogenic stages of main ore minerals in Delney copper deposit are summarized. It is considered that the main ore mineral pyrite is divided into three stages, chalcopyrite and sphalerite are divided into two periods, and pyrrhotite and magnetite have one phase altogether. According to the data of electron probe, the pyrite and chalcopyrite in the orebody are obtained. The main minerals such as sphalerite are produced in the medium and low temperature hydrothermal environment. The petrogeochemical characteristics show that the amphibolite is a combination of basic-ultrabasic rocks, and its main rock types are andesite and basalt. Picrite is characterized by low potassium metamorphic calc-alkaline. Rare earth elements are enriched in light rare earth elements and depleted in heavy rare earth elements with weak europium positive anomalies. The large ion lithophile elements, such as RB, Bao, Sr and so on, are obviously enriched in the rocks, and the high field strength element Nbtadao U is relatively depleted, while Pb is found. The zircon U-Pb chronology in the study area shows that the metallogenic time of zircon is 310.0 卤4.7 Ma, which belongs to the late Carboniferous. It is preliminarily considered that the Delnier copper polymetallic deposit is a kind of composite metallogenic deposit characterized by submarine exhalation and depositional metallogeny and characterized by late superposition metallogeny. It can be concluded that the ore-forming hydrothermal fluid ejects and deposits along the fissure. There is a set of carbonaceous iron-siliceous slate at the top of the orebody. The ultrabasic rock compresses and deforms the main orebody under the influence of late tectonics, and affects the superposition process of cobalt ore and pyrrhotite in the contact position. The ore deposit experienced various forms of structural failure and change of location during the subsequent superposition and metallogenic process. On the basis of this, the ore-prospecting markers of Delney deposit were put forward, that is, fold tectonic turning end and tectonic breccia belt. The physical and chemical zones of ultrabasic rock body, the contact zone between ultrabasic rock body and surrounding rock, the overthrust tectonic footwall, and the ultrabasic rock structural lens.
【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】：2016
【分类号】：P618.2

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