投稿时间：2014-06-13
修订日期：2014-09-25
网络发布日期：2015-05-06
中文摘要:宝山铅锌矿床是湘南地区代表性矿床之一。宝山铅锌矿床的成矿作用与156 ~ 158 Ma的宝山花岗闪长斑岩密切相关。花岗闪长斑岩主要由古老地壳部分熔融而成。为确定成矿物质来源, 文章系统研究了宝山铅锌矿床的硫、铅、碳、氧同位素组成特征。矿床中硫化物黄铁矿、闪锌矿、方铅矿的δ34S值呈狭窄的塔式分布, 变化在-2.17‰~6.46‰之间, 平均值为3.13‰。δ34S值总体表现为δ34S黄铁矿 > δ34S闪锌矿 > δ34S方铅矿, 表明硫同位素分馏基本达到了平衡。矿石、花岗闪长斑岩和赋矿地层硫同位素对比研究表明, 矿石中的硫主要由岩浆分异演化而来, 岩浆中的硫主要来自古老地壳。矿石206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值分别为18.188~18.844、15.661~15.843和38.562~39.912, 赋矿地层206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值分别为18.268~19.166、15.620~5.721和38.364~39.952。矿石铅同位素组成比地层中的更富放射性成因铅, 矿石中部分铅来自宝山花岗闪长质岩浆, 在成矿流体运移过程中有部分地层铅参与了成矿, 岩浆中的铅主要来自古老地壳。热液方解石的碳、氧同位素组成介于岩浆和赋矿碳酸盐岩的碳、氧同位素之间, 主要是由于岩浆流体和碳酸盐岩不同比例的水岩反应所致, 测水组有机碳的加入造成了部分热液方解石δ13CPDB值偏低。
Abstract:The Baoshan Pb-Zn deposit is one of the representative deposits in southern Hunan Province. The metallogeny of the Baoshan Pb-Zn deposit is closely related to the 156~158 Ma granodiorite porphyry. The granodiorite porphyry was mainly derived from partial melting of old crustal rocks. Sulfur, lead, carbon and oxygen isotope geochemical results are analyzed and discussed in this paper in order to constrain the sources of metallogenic materials. The δ34S values of pyrite, sphalerite and galena in the Baoshan deposit show a narrow tower-like distribution, ranging from -2.17‰ to +6.46‰ with an average of 3.10‰. The δ34S values of all sulfides display a decreasing trend from pyrite through sphalerite to galena (δ34Spyrite>δ34Ssphalerite>δ34Sgalena), which suggests a sulfur isotopic equilibrium. Based on the characteristics of sulfur isotope of sulfides, the authors infer that sulfur in magma was mainly derived from old crust and that sulfur in ores was dominantly derived from the magma. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios for sulfides vary in ranges of 18.188 ~ 18.844, 15.661 ~ 15.843 and 38.562 ~ 39.912, respectively. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios for wall rocks are 18.268 ~ 19.166, 15.620 ~ 15.721 and 38.364 ~ 39.952, respectively. Lead isotopic compositions of some ore sulfides are significantly more radiogenic than those of the ore-hosting wall rocks. A part of lead of the ores in the Baoshan deposit might have come from the granodioritic magma. The lead in the magma mostly originated from old crust. A part of lead in ores was derived from the ore-bearing strata during the migration process of the ore-forming fluid. The carbon and oxygen isotopic compositions of the hydrothermal calcites vary between those of magma and carbonates and it is deduced that the hydrothermal calcites might have been formed by the interaction between magmatic water and carbonates in variable proportions. The relative low δ13CPDB values of hydrothermal calcites were probably related to involvement of sedimentary organic matter in the Ceshui Formation.
keywords:geochemistry S isotopes Pb isotopes C-O isotopes sources of metallogenic materials Baoshan Pb-Zn deposit southern Hunan Province
文章编号：
中图分类号：P618.42;P618.43
文献标志码：
基金项目:本研究得到国家基础发展项目(编号: 2012CB416705)和国家自然科学重点基金(编号: 41230315)联合资助
引用文本：
谢银财,陆建军,杨平,马东升,徐兆文,章荣清,蔡杨,丁腾.2015.湘南宝山铅锌矿床硫、铅、碳、氧同位素特征及成矿物质来源[J].矿床地质,34(2):333~351XIE YinCai,LU JianJun,YANG Ping,MA DongSheng,XU ZhaoWen,ZHANG RongQing,CAI Yang,DING Teng.2015.S, Pb, C and O isotopic characteristics and sources of metallogenic materials of Baoshan Pb-Zn deposit, southern Hunan Province[J].Mineral Deposits34(2):333~351
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