【作者】 陈伟；

【导师】 刘家军；

【作者基本信息】 中国地质大学(北京) ， 矿物学、岩石学、矿床学， 2016， 硕士

【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。更多还原

【Abstract】 The Qixiashan Pb-Zn deposit is situated in Qixia district, Nanjing City, Jiangsu Province. It is mainly composed of Mian Huadi, Ping Shantou, Hu Zhuashan, Bei Xiangshan, Gan Jiaxiang, Xi Ku and other ore blocks from east to west. The author carried out a detailed study of deep part about Hu Zhuashan ore block. Based on studying and analyzing the previous results and having finely field geological work, through mineralogy, fluid inclusions and isotope geochemical characteristics in depth study, the author discussed the metallogenetic mechanism combined with regional tectonic evolution background to provide more evidence about genesis and deep prospecting of the Qixiashan Pb-Zn deposit.The ore body is mainly controlled by the Silico-calcium lithologic interface, vertical fault, unconformity surface, the ancient karst and concealed intrusion. There are two kinds of Silico-calcium lithologic interface. One is composed by fault wall of F2 and another one by unconformity surface. The ore body is primarily present at the calcium-rich part of the Silico-calcium lithologic interface. Ore minerals include sphalerite, pyrite, galena. Gangue minerals include calcite, quartz, dolomite. The main structures include breccia structure, disseminated structure, massive structure, vein structure, reticular and vein structure, streaked structure, crumb structure. Ore textures include subhedral granular texture, metasomatic relict texture, skeleton crystal texture, emulsion texture, poikilitic texture, reticular texture, crumpled texture, cataclastic texture. Through field work and the microscopic identification, the ore-forming processes of the Hu Zhuashan ore block can be divided into four stages, which are characterized by the pyrite-quartz assemblage, the galena-sphalerite assemblage, the galena-sphalerite-pyrite assemblage, the carbonate-barite-gold(silver) assemblage.Studies of electron-probe micro-analysis(EPMA) have shown that the pyrite, sphalerite ore minerals of Hu Zhuashan ore block are mainly magmatic hydrothermal genesis. Studies of fluid inclusions have shown that the deposit is dominated by vapor-liquid two phase inclusions. The homogenization temperature is 125~294°C while the salinity ω(NaCleqv) is 1.06%~7.59% and the density is 0.84~0.96g/cm3. Laser Raman spectroscopy indicates that the principal gas and liquid components of the fluid inclusions is H2 O and a little CO2. So the ore-forming fluid is a type of low-temperature, low-salinity, low-density H2O-CO2-NaCl system. Studies of hydrogen and oxygen isotope indicates that the ore-forming fluid is a kind of complicated fluid which is derived from magmatic water and is mixed by meteoric water, hot brine, organic water. The ore-forming fluid is dominated by magmatic water in the early stage of mineralization. The proportion of meteoric water is increased which makes the salinity lower constantly along with the mineralization. Combined with sulfur and lead isotope of the previous results, studies have shown that the metallogenic materials of the Qixiashan deposit mainly come from the the mantle and deep crust. It means the metallogenic materials of the Qixiashan deposit mainly come from concealed intrusion and Sinian system strata. From what has been discussed above, the Qixiashan Pb-Zn deposit is a kind of epithermal-mesothermal deposit related to magmatic hydrothermalism fluid.更多还原