投稿时间：2015-02-07
修订日期：2016-02-17
网络发布日期：2016-08-25
中文摘要:宝山铜铅锌多金属矿床是湖南重要的铅锌生产基地。矿床内矽卡岩型铜（钼）矿化受侏罗纪花岗闪长斑岩的控制，而主要的铅锌矿体则产于远离岩体的碳酸盐地层中，且缺乏可靠的矿化年龄限制。为了查明宝山铅锌矿体与花岗闪长斑岩之间的成因关系，文章对宝山花岗岩类中浸染状黄铁矿的硫同位素和钾长石的铅同位素，以及铅锌矿石萤石脉石的流体包裹体进行了测试和研究，并与前人报道的铅锌硫化物矿石的硫、铅同位素进行了对比，尝试为宝山铅锌矿化的物质来源及成因提供依据。研究表明，花岗闪长斑岩中浸染状黄铁矿的δ34S值为+1.5‰~+3.5‰，与铅锌矿石硫化物（方铅矿、闪锌矿及黄铁矿）相一致；同时，花岗岩类中钾长石的铅同位素组成206Pb/204Pb、207Pb/204Pb和208Pb/204Pb分别为18.4789~18.7668、15.6835~15.7220和38.7903~39.1035，具有壳源的特征，且与铅锌矿石硫化物的铅同位素分布范围相吻合。宝山矿床的硫、铅同位素特征表明，花岗闪长斑岩应是铅锌矿化的主要硫源及金属来源。宝山矿床铅锌矿石萤石中的流体包裹体具有低温（130~150℃）、低盐度（<8%）的特征，可能是岩浆热液演化到晚期的产物。结合已有的有关资料加以对比和分析，研究认为，宝山铅锌矿床的成矿物质应来源于花岗闪长岩的岩浆期后热液，在热液演化晚期迁移到远端地层中沉淀，形成了宝山的主要铅锌矿体。
Abstract:The Baoshan Cu-Pb-Zn polymetallic deposit in southern Hunan Province is one of the classic skarn-type ore deposits in this area. This deposit contains disseminated chalcopyrite and molybdenite within skarn in the contact zone of Jurassic granodiorite-porphyry and Carboniferous sedimentary carbonate, with sulfide ores located within distal carbonate-hosted stratabound and fault controlled orebodies. The metals and fluids that formed the Cu-Mo mineralization in the study area were derived from granodiorite-porphyry, as indicated by their close spatial and temporal relationships; however, the source of the Pb-Zn mineralization in this deposit remains obscured because of the distal orebodies and their uncertain mineralization age. In this paper, the authors presented new sulfur, lead isotope data and microthermometry study of pyrite disseminations in granitoids as well as potash feldspar and fluid inclusions in fluorite gangue, respectively, and comqared these data with previous studies in order to provide insight into the genesis of Pb-Zn mineralization. The (34S values of pyrite disseminations in granodiorite-porphyry range from +1.5‰ to +3.5‰ and are consistent with the (34S values of sulfide ores in the Baoshan deposit; in addition, the lead isotopic compositions of potash feldspar have the 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of 18.4789~18.7668, 15.6835~15.7220 and 38.7903~ 9.1035, respectively, which also are consistent with the values of sulfide ores, with both of them having the crustal signatures. The sulfur and lead isotope features in the Baoshan deposit indicate that granodiorite-porphyry was the main source of the ore-forming sulfur and metals that precipitated in the sulfide orebodies. The fluid inclusions in fluorite gangue have low homogenization temperature (130~150℃) and low salinity (<8%), showing a signature of late stage magmatic-hydrothermal fluids with low temperature and salinity. Combined with previous studies, it can be concluded that the ore-forming materials were derived from the basement, they were added to the magma as the basement melted, and these ore-forming materials migrated with the upward migration of the magma and finally precipitated in the distal sulfide orebodies during the late magmatic-hydrothermal stage.
keywords:geochemistry Pb-Zn mineralization granodiorite-porphyry sulfur and lead isotopic compositions ore-forming materials Baoshan deposit Hunan Province
文章编号：
中图分类号：P618.41;P618.42;P618.43
文献标志码：
基金项目:本文得到国家重点基础研究发展计划（资助项目号：2012CB416705）和国家自然科学重点基金（编号：41230315）联合资助
引用文本：
丁腾,马东升,陆建军,章荣清,谢银财.2016.湖南宝山矿床花岗岩类硫-铅同位素和流体包裹体研究及其成因意义[J].矿床地质,35(4):663~676DING Teng,MA DongSheng,LU JianJun,ZHANG RongQing,XIE YinCai.2016.Sulfur and lead isotopic compositions of granitoids and fluid inclusions in Baoshan deposit, Hunan Province[J].Mineral Deposits35(4):663~676
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