江苏栖霞山铅锌矿床地质地球化学特征及成因研究

发布时间：2018-03-24 09:12

  本文选题：栖霞山铅锌矿床　切入点：中低温热液型　出处：《中国地质大学(北京)》2016年硕士论文

【摘要】：栖霞山铅锌矿床位于江苏省南京市栖霞区,矿床自东向西主要由棉花地、平山头、虎爪山、北象山、甘家巷、西库等多个矿段组成,本文以虎爪山矿段深部成矿地质特征为重点研究对象,在整理已有研究成果和进行细致野外地质工作的基础上,进行了矿物学、流体地球化学、同位素地球化学等方面的研究,并结合区域构造演化背景,探讨了矿床的成矿机制,为该矿床的成因分析和深部找矿提供了更多依据。矿体主要受硅钙面、纵向断裂、不整合面、古岩溶构造带及隐伏岩体等多重地质要素控制,其中硅钙面主要为由F2断裂上下盘地层形成的和由断碎不整合面上下构造层形成的两种硅钙面,矿体主要赋存于硅钙面钙质岩性一侧。矿石矿物主要有黄铁矿、闪锌矿、方铅矿等;脉石矿物主要有石英、方解石、白云石等。矿石的构造主要有角砾状构造、浸染状构造、块状构造,其次为脉状、网脉状、团块状以及条带状构造等,矿石结构主要有粒状结构、交代溶蚀结构、骸晶结构、乳滴状结构、显微包含结构、网状结构、碎裂结构和揉皱结构等。通过野外工作和镜下鉴定,将成矿作用过程分为石英-黄铁矿阶段、闪锌矿-方铅矿阶段、黄铁矿-闪锌矿-方铅矿阶段、碳酸盐-重晶石-金(银)阶段等四个阶段。通过对黄铁矿、闪锌矿电子探针数据的分析,指示虎爪山矿段深部黄铁矿、闪锌矿等矿石矿物主要为岩浆热液成因。流体包裹体研究结果显示,矿床主要发育气液两相包裹体,流体包裹体均一温度变化范围在125~294℃之间,盐度变化范围为1.06~7.59wt%NaCl,密度变化范围为0.84~0.96g/cm3,激光拉曼探针分析显示,气液相成分仅包含H2O和少量CO2,因此矿床成矿流体为中低温、较低盐度、较低密度的H2O-NaCl-CO2体系流体。H-O同位素研究表明,成矿热液主要为岩浆热液和大气降水、热卤水、有机水混合的复杂流体,成矿作用早期以岩浆水为主,晚阶段成矿流体类似大气降水。结合前人S、Pb同位素的研究,成矿物质的来源主要为地幔及地壳深部,即主要来自于矿区深部推测隐伏岩体和下伏震旦系地层。综合研究认为,矿床成因类型为与深成岩浆热液作用有关的中低温热液型矿床。
[Abstract]:Qixiashan Pb-Zn deposit is located in Qixia District, Nanjing City, Jiangsu Province. From east to west, the deposit is mainly composed of several ore sections, such as cotton field, Pingshantou, Hujiashan, North Xiangshan, Ganjiaxiang, Xiku and so on. In this paper, the ore-forming geological characteristics in the deep part of the Hujiushan ore section are taken as the main research objects. On the basis of sorting out the existing research results and carrying out detailed field geological work, the mineralogy, fluid geochemistry, isotope geochemistry and so on have been studied. Combined with the regional tectonic evolution background, the metallogenic mechanism of the deposit is discussed, which provides more basis for the genetic analysis and deep prospecting of the deposit. The paleokarst tectonic belt and concealed rock mass are controlled by many geological elements, in which the calcium siliceous surface is mainly formed by the upper and lower plate strata of the F2 fault and the two kinds of calcium siliceous surfaces formed by the upper and lower tectonic layers of the faulted unconformities. The ore bodies mainly occur on the side of the calcareous lithology of the calcium silicate surface. The ore minerals are mainly pyrite, sphalerite, galena, etc. The gangue minerals are mainly quartz, calcite, dolomite, etc. The ore structure mainly consists of granular structure, metasomatic solution structure, skeleton crystal structure, emulsion droplet structure, microscopic inclusion structure, reticular structure. Through field work and microscopic identification, the metallogenic process is divided into quartz-pyrite stage, sphalerite-galena stage, pyrite -sphalerite-galena stage, etc. Through the analysis of electron probe data of pyrite and sphalerite, the deep pyrite in the Hujiushan ore section is indicated. The ore minerals such as sphalerite are mainly magmatic hydrothermal origin. The results of fluid inclusion study show that gas-liquid two-phase inclusions are mainly developed in the deposit, and the homogenization temperature of fluid inclusions varies from 125 鈩，

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