投稿时间：2014-09-23
修订日期：2015-04-20
网络发布日期：2015-07-02
中文摘要:梅山铁矿位于江苏省南京市雨花台区,铁矿主矿体的顶部和外围蚀变带中新发现了中型规模的金矿床,金矿体赋存于辉长闪长玢岩和下白垩统大王山组安山质凝灰岩、辉石安山岩的外接触带,矿石主要由黄铁矿、磁铁矿、少量的黄铜矿和方铅矿以及脉石矿物组成。金成矿阶段的石英、方解石和白云石中发育富液相包裹体、富气相包裹体、气体包裹体及含子晶三相包裹体。流体包裹体的均一温度主要集中在150~230℃之间,盐度w(NaCleq)主要集中在2%~8%之间,指示金矿化阶段成矿流体具中低温、低盐度的特点。金矿石中脉石矿物石英、方解石和白云石的δDV-SMOW值介于-154.0‰~-110.9‰之间,计算得到的δ18O水值为-1.3‰~6.8‰,表明成矿流体为岩浆水和雨水的混合流体。金矿石中黄铁矿的δ34S值介于-0.2‰~9.3‰之间,均值为5.8‰,与梅山铁矿辉长闪长玢岩中浸染状黄铁矿的δ34S值相近。白垩纪岩浆活动是梅山铁金矿床形成的必要条件,金矿与铁矿形成于同一成矿系统,均与辉长闪长玢岩具有密切的时空和成因上的联系,金矿床为成矿末期的产物。
Abstract:The Meishan iron deposit is located in the northern part of the Ningwu volcanic basin within the northern Yangtze Craton, southeast China. The Au mineralization within the Meishan deposit occurs above and/or alongside the main magnetite orebody, and is hosted by andesitic tuffs and pyroxene andesite of the Late Cretaceous Dawangshan Formation close to the contact between the gabbro-diorite porphyry and the formation. The gold ore is dominated by pyrite, magnetite, quartz, calcite and dolomite with minor chalcopyrite and galena. Four types of fluid inclusions, i.e., liquid-rich, gas-rich two phase inclusions, pure gas monophase inclusions and daughter mineral-bearing three-phase inclusions in quartz, calcite and dolomite were analyzed. The homogenization temperatures of fluid inclusions range from 120℃ to 392℃, with the majority between 150℃ and 230℃. The salinities w(NaCleq) of fluid inclusions range from 2.07% to 28.33%, with the majority between 2% and 8%, indicating that the association of ore-forming fluid with gold mineralization was characterized by medium-low temperature and low salinity. The δDV-SMOW values of quartz, calcite and dolomite vary from -154.0‰ to -110.9‰, and the δ18OH2O values vary from -1.3‰ to 6.8‰, indicating the mixing origin of magmatic fluid and meteoric water. The δ34S values of pyrite at the stage of gold mineralization vary from -0.2‰ to +9.3‰, with mean value of 5.8‰. The sulfur in the gold orebodies of the Meishan deposit possibly suggests derivation from magma sources. The formation of iron orebodies was followed by gold mineralization in the Meishan deposit. The iron and gold mineralization was associated with Cretaceous gabbro-diorite porphyry, and occurred within a large-scale magmatic-hydrothermal system.
keywords:geochemistry fluid inclusion H-O-S isotopes magmatic-hydrothermal system gold deposit Meishan iron deposit
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中图分类号：P618.31
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基金项目:本文得到国家自然科学基金项目(编号: 41372091)和国家重点基础研究发展计划"973计划"(编号: 2012CB416803)联合资助
引用文本：
王铁柱,余金杰,车林睿,陆邦成,王贤伟.2015.宁芜地区梅山金矿床的成矿流体特征及矿床成因[J].矿床地质,34(3):565~580WANG TieZhu,YU JinJie,CHE LinRui,LU BangCheng,WANG XianWei.2015.Characteristics of ore-forming fluid and genesis of gold deposit adjacent to Meishan iron deposit, Nanjing, Jiangsu Province[J].Mineral Deposits34(3):565~580
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