投稿时间：2016-01-08
修订日期：2017-04-24
网络发布日期：2017-07-04
中文摘要:李梅铅锌矿床位于扬子地块的东南缘，是湘西-鄂西成矿带花垣矿田中较早发现的超大型铅锌矿床之一，矿体呈层状、似层状产于寒武系清虚洞组藻灰岩中。文章通过对其进行C、O、S、Pb同位素地球化学及流体包裹体激光拉曼的研究，探讨了成矿流体和成矿物质的来源及演化。研究结果表明：成矿期热液方解石的δ13CPDB为-2.79‰~1.11‰，δ18OSMOW为14.59‰~23.05‰，表明成矿流体中的CO2主要来自于寒武系碳酸盐岩的溶解，部分成矿期及成矿后的热液方解石与有机质的热化学还原作用有关。激光拉曼研究显示包裹体气相成分中含大量的CH4、H2S、N2及其他烃类，推测已经演化到高成熟阶段的有机质可能以古油气藏的形式参与了成矿作用，闪锌矿中气态含碳质沥青包裹体的出现暗示有机质的热化学还原反应参与了铅锌成矿过程。矿石中硫化物的δ34SCDT值为+26.30‰~+34.66‰，平均值为+30.52‰，表明还原S主要来自成矿流体中海水硫酸盐充分的热化学还原作用。矿石硫化物的Pb同位素组成变化范围较小，206Pb/204Pb、207Pb/204Pb、208Pb/204Pb分别为17.999~18.235、15.584~15.789、38.147~38.576，推测成矿物质主要来源于元古界浅变质基底板溪群和寒武系下统牛蹄塘组黑色页岩，部分来自于清虚洞组赋矿围岩。
Abstract:The Limei Pb-Zn deposit located on the southeastern margin of the Yangtze block, is one of the earlier-discovered and giant Pb-Zn deposit occurring in bedded and stratoid forms and hosted by lower Cambrian algal limestone in the Huayuan orefiled of the Xiangxi-Exi metallogenic belt. C, O, S and Pb isotope geochemistry was analyzed in this paper in order to understand comprehensively the source and evolution of the metallogenic material and the ore fluids. The results show that δ13CPDB values of the ore-stage hydrothermal calcites are -2.79 ‰~1.11 ‰, and δ18OSMOW are 14.59‰~23.05‰, indicating that the CO2 in the ore-forming fluid was derived from the dissolution of Cambrian carbonates, whereas the post ore-stage and parts of ore-stage hydrothermal calcites should be related to the thermochemical reduction reaction of the organic matter. The laser Raman spectroscopy shows that the gas components have large quantities of CH4, H2S, N2 and other hydrocarbons, and the authors thus infer that the organic matter at high mature stage of evolution was involved in mineralization in the form of oil-gas field. The presence of gas bituminiferous inclusions in sphalerite suggests that the thermochemical reduction reaction was involved in mineralization. The δ34SCDT values of sulfides are +26.30‰~+34.66‰, suggesting that the sulfur must have been derived from the fully thermochemical reduction reaction of sulfates from the ore-forming brine. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values for the ores vary in the range of 17.999~18.235, 15.584~15.789, and 38.147~38.576 respectively, implying that the metallogenic material was most likely derived from the Proterozoic low metamorphic basement and the lower Cambrian Niutitang Formation black shale, with part of the ore metals from the host algal limestone.
文章编号：
中图分类号：P618.41;P618.42
文献标志码：
基金项目:本研究得到中国地质调查局项目（编号：12120114016601）、国家自然科学基金面上项目（编号：41272097）、中央高校基本科研业务费专项资金（编号：CUG120702）和中国地质大学（武汉）教学实验室开放基金项目（编号：SKJ2014010）的联合资助
引用文本：
胡太平,王敏芳,丁振举,何谋惷,王彦博,郭晓南.2017.湘西花垣李梅铅锌矿床C、O、S、Pb同位素特征及成矿物质来源[J].矿床地质,36(3):623~642HU TaiPing,WANG MinFang,DING ZhenJu,HE MouChun,WANG YanBo,GUO XiaoNan.2017.C, O, S and Pb isotopic characteristics and sources of metallogenic materials of Limei Pb-Zn deposit in Huayuan County, western Hunan Province[J].Mineral Deposits36(3):623~642
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