【作者】 伍永田；

【导师】 陈松岭；

【作者基本信息】 中南大学 ， 矿产普查与勘探， 2009， 博士

【摘要】 论文以分散元素地球化学理论为指导,从广西大厂矿田区域成矿地质背景分析入手,应用岩石学、构造地质学、稀土元素地球化学、微量元素地球化学、稳定同位素地球化学、包裹体地球化学等多学科知识对大厂矿田的矿床地质特征、矿床地球化学特征、矿床成因进行了比较系统和深入的研究,进而在全面总结成矿规律的基础上,开展了大厂矿田铟的富集规律研究工作。从大厂矿田区域地质特征分析入手,应用地洼学说成矿学理论,阐述了大厂矿田矿田经历了前地槽、地台及地洼(活化)三个大的构造发展演化阶段。矿区前地槽主要为沉积期,形成了前三叠纪的原岩地层,至印支期,区域上升成为地台,至燕山期,地台活化,进入地洼阶段,区域发生大规模构造、岩浆活动,地洼阶段为大厂矿田的重要形成时期。首次对大厂矿田中In与近矿围岩、岩浆岩以及矿石的微量元素、稀土元素地球化学特征的相互关系进行了研究,揭示了微量元素和稀土元素在成岩、成矿过程中所反映的地球化学行为特征,成矿物理化学环境特征表明In在相对偏氧化的弱碱性成矿环境中易得到富集。首次对大厂矿田中In与主要成矿金属元素的关系进行了研究,发现铟和锡之间存在正相关关系。In与Sn在地球化学行为的相似性,使得Sn与In同迁移、同沉淀。Sn在In的矿质活化、迁移及进入闪锌矿晶格过程中起着十分重要的作用；In与Zn之间呈负相关关系,说明In在闪锌矿结晶早期就进入晶格中,此外证明了In在趋向于高温时进入闪锌矿晶格中。首次对大厂矿田In与岩浆岩的关系进行了研究,研究表明在成矿作用过程中岩浆岩起到不可忽略的作用,越靠近岩体,铟的含量越局。通过对大厂矿田矿石与区域地层、岩浆岩稀土特征的研究,表明大厂矿田的成矿物质可能是多来源的,而不仅仅是某一个特定地层或岩浆岩所提供的。但是同车江组、五指山组、榴江组、罗富组、纳标组的稀土特征与矿石稀土特征有一定的共同点,总体表现为轻稀土富集、重稀土平坦,Eu和Ce亏损,反映出矿石对容矿岩石稀土元素的继承,即矿石的稀土元素主要来自容矿地层。通过对In在各个中段含量的变化研究,说明大厂矿田In的含量与深度成正相关关系,也证明了在同一矿体中,In的含量与成矿温度呈正相关关系。通过对大厂矿田In的富集规律的研究,以大厂矿田的矿床成因、成矿规律以及矿化在空间上所表现的各种富集变化规律为主要预测依据,提出了在大厂矿田有如下几个有利部位易形成富铟矿体：围绕龙箱盖花岗岩体是形成富铟矿体的有利部位,以前的工作都是围绕着花岗岩体寻找锡矿体、锑矿,而忽略了对其中铁闪锌矿、黄铁矿、磁黄铁矿等的研究,从目前掌握的情况来看,以及在铟的价值越来越大的情况下,在龙箱盖周围的矿体中大量的黄铁矿、磁黄铁矿和铁闪锌矿是具有巨大的经济价值的。100#矿体下部的105#矿体是另一个铟储量巨大的富铟矿体,从目前的勘探情况来看,100#矿体是世界上已知的铟储量最大的矿体,但是其成矿温度要比105#矿体低,且105#矿体是综合品位更高的锡石硫化物型矿体,105#矿体是下一个值得重点研究的对象。铜坑—长坡矿床也是区内另一个大型的富铟矿体。更多还原

【Abstract】 With the guideline of the geochemical theory of rare earth element (REE), starting from analyses of regional metallogenic background of Dachang mine fields in Guangxi province, geological characteristics, geochemical characteristics and metallogenic genesis are studied systematically and deeply by using the knowledge of petrology, structural geology, REE geochemistry, geochemistry of trace element, stable isotope geochemistry and inclusions geochemistry. On the basis of summarizing of metallogenic regularities roundly, researches on the enrichment regularity of indium have been done.Proceeding with analyses of regional metallogenic background of Dachang mine fields by using Diwa metallogenic theory, the author has explained that Dachang mine fields has undergone three big developing evolution stages, i.e. Pregeosyncline, platform and Diwa stage. The pregeosyncline period in which the protolith stratum of pre-Triassic was formed; during Indo-Chinese epoch, the region was arised and platform formed; When Yanshanian period, the platform was moved into Diwa stage by activating, large-scale tectonic and magmatic activities happed in that region, which was considered as significant forming stage of Dachang mine fields.The author, for the first time, have studied on the geochemical feature of the trace element and the REE of the country rock near orebody, magmatite and ore; pointed out the geochemical action feature of the trace element and REE in the ore-forming process and diagenetic stage, The physical chemical features suggest indium emplaced in relative oxidized and weakly alkaline ore-forming environment.The author, for the first time, has studied on the relationship between indium and other metallogenic element, and then discovers that there is positive relation between Sn and In. The similarity of geochemical behaviors of Sn and In made them migrate and deposit together. Sn play a very important role during the process of activating, migrating and entering sphalerite lattice. Negative relation between Sn and In show that In have entered the sphalerite lattice before the crystallization of sphalerite, in addition, it also proved that In tend to enter the sphalerite lattice under higher temperature.The author, for the first time, have studied on the relationship between indium and magmatite, the result shows that magmatite play a very important role during the diagenetic stage.The more near to the rock mass, the more high the content of indium.The research on the regional stratum and trace elemental feature of magmatite show that mineralizing materials are of multi-sources and are not derived from special stratum and magmatite. The geochemical feature of trace element Tongchejian group, Wuzhishan group, Liujian group and Nabiao group have in common with the feature of trace element of ore. It display generally that Light rare earth element enriched, weight rare earth element is flat, and Eu and Ce is loss. It also reflected ore inherited the rare earth element of host-rock.The research on the variety of indium in the different mean gradation illustrate that the content of indium kept positive relation to depth and proved that the content of indium has positive relation with metallogenic temperature in one orebody.Studied on the enrichment regularity of indium of Dachang mine field, based on the metallogenic genesis, rule and the variety of enrichment regularity in spatial, the author proposed some favorable place as follows:The first favorable place is around the Longxianggai granite rock mass. The formerly work focus on the granite rock mass which is liable with tin and antimony and neglect the study on marmatite, pyrite, and pyrrhotite. According the new exploration material and the rising of value of indium, plenty of pyrite, marmatite and pyrrhotite around the Longxianggai granite rock mass have very tremendous value.105 orebody, lied in the bottom of 100#orebody, is another large-scale enriched indium orebody. According the present exploration material,100 orebody is the known maximal indium reserves in the world, its metallgenic temperature is lower than the temperature of 105#, which is a tin spar-sulfide orebody with higher comprehensive grades. So, 105#orebody is the next key object. Tongkeng-Changpo mineral deposit is also another large-scale enriched indium orebody.更多还原