【作者】 王晶；

【导师】 张术根；

【作者基本信息】 中南大学 ， 构造地质学， 2011， 硕士

【摘要】 凡口铅锌矿床是我国有名的超大型铅锌矿床之一,其位于南岭成矿带曲仁构造盆地的北缘。本文以宏观地质为基础,利用成因矿相学和成因矿物学,首先研究了凡口矿区的矿石类型、矿石物质组成、矿石结构构造特征、矿物世代特征、矿物共生组合等矿相学特征并得出该矿田成矿作用的期次和阶段及矿物生成顺序；其次对矿石中主要矿物的形态与内部结构、闪锌矿的微区成分特征、闪锌矿流体包裹体成分、闪锌矿成矿温度及硫同位素组成特征等进行成因矿物学研究。为矿区深边部找矿预测研究提供新的资料,从而有助于本区新一轮找矿勘查工作。主要的认识如下：1、根据凡口矿区矿石结构构造、矿物共生组合、矿物形成世代、矿化围岩蚀变等特征及其时空分布,不考虑表生氧化期的变化情况,可以确定矿区硫化物成矿全过程具有两个成矿期和三个成矿阶段。两个成矿期分别为沉积成岩成矿期和热液成矿期。三个成矿阶段分别为早期黄铁矿成矿阶段,中温铅锌硫化物成矿阶段和低温铅锌硫化物成矿阶段。2、从代表性矿体的矿石组构和矿物组合特点来看,凡口矿区多阶段成矿表现显著。其中闪锌矿具有三次结晶：第一世代棕黑色闪锌矿；第二世代棕褐色闪锌矿；第三世代黄褐色闪锌矿。方铅矿亦具有三次结晶,而黄铁矿在矿体内部则至少有四个世代。3、根据闪锌矿的铁含量、闪锌矿流体包裹体均一温度及变化规律、闪锌矿—方铅矿对的硫同位素平衡分馏温度,认为凡口矿区铅锌硫化物成矿作用发生在中—低温环境,但随着成矿作用的演化,自早到晚是经历了升温再到降温的过程,其中降温过程比较显著。4、凡口矿区铅锌硫化物的成矿流体为Na+-Cl--SO42-成分类型,而δ34S的组成经历由高到低的变化,显示各阶段成矿作用是相同成矿体系有规律的演化结果,但的δ34S值从中期阶段到晚期阶段远比早期阶段到中期阶段降低幅度更加显著,显示成矿流体在成矿晚期至少有部分的δ34S显著较低的流体参与成矿。更多还原

【Abstract】 Fankou Pb-Zn ore deposit is one of the famous super-large Pb-Zn deposits in China. It is situated on the north of Quren structural basin in Nanling mineralization belt. Directed by the genetic mineralography and genetic mineralogy, based on the macro-geological research, firstly, some mineralograph properties of ore, such as ore type, ore composition, texture and structural feature, characteristics of mineral generations, mineral assemblage in Fankou Pb-Zn ore deposit have been researched. And the stage of mineralization and mineral formation order of this ore field was obtained. Secondly, based on X-ray diffraction, microprobe analysis, homogenization temperature and composition measurement of fluid inclusions and sulphur isotopic composition measurement, some genetic mineralogical properties of lead-zinc sulphides (especially sphalerite) have been studied. It provides new data for the prediction of depth and margin prospecting in the mining area. Thus, this contributes to the work of new round of prospecting in this area. The major cognition is as follows:1. According to the characteristics of texture and structural feature of ore, mineral assemblage, mineral generations and mineralized wall rock alteration in Fankou Pb-Zn district. Without considering the changes of supergenesis period, the whole sulfide ore mineralization process is classified into two metallogenic period and three mineralization stages. Two periods are sedimentary diagenetic period and hydrothermal metallogenic period. Three stages are the early pyrite mineralization stage, middle temperature lead-zinc sulphide mineralization stage, and low temperature lead-zinc sulphide mineralization stage.2. From the characteristics of ore fabric and mineral assemblage in representative ore-bodies, it can be discovered that multi-stage mineralization in Fankou ore district is significantly. Among them, sphalerite has three generations:the first generation of brown-black sphalerite, the second generation of brown sphlerite, the third generation of yellow-brown sphalerite. Galena also has three generations. And the pyrite in ore-body at least has four generations.3. According to the iron content of sphalerite, the homogenization temperature of sphalerite fliud inclusions.δ34S fractionation equilibrium temperature of sphalerite and galena, it is considered that the mineralization of lead-zinc sulfide in Fankou ore district occurred in middle-low temperature environment. But with the evolution of mineralization, from the early stage to the last stage, the temperature varied from low through high to low again, in which the cooling process is more significant.4. The compositions of ore-forming fluid in Fankou Pb-Zn ore deposit is Na+-Cl-SO42-.The value ofδ34S decreased, but the decreasing was much more drastic from the second to the third stage than from the first to the second stage, implying that a portion of newly-produced solution with much lower values of 834S participated in the ore-forming fluid during the third stage.更多还原