黔西北杉树林铅锌矿床硫化物微量元素地球化学特征_吴莎.pdf

第 43 卷 第 4 期 矿矿 物物 学学 报报 Vol.43,No.4 2023 年 8 月 ACTA MINERALOGICA SINICA Aug.,2023 文章编号：文章编号：1000-4734(2023)04-0469-12 黔西北杉树林铅锌矿床硫化物微量元素地球化学特征 吴莎1，金中国1,2*，郑明泓2，张伦尉2，刘玲2，曾道国3，蔡国盛3（1贵州大学 资源与环境工程学院，贵州 贵阳 550025；2.贵州省有色金属和核工业地质勘查局，贵州 贵阳 550005；3.贵州省有色金属和核工业地质勘查局 地质矿产勘查院，贵州 贵阳 550005）摘要摘要：杉树林铅锌矿床位于威宁水城成矿带的南东段，是黔西北铅锌成矿区代表性矿床。本文在野外和镜下鉴定基础上，识别出该矿床存在早期（Py）和晚期（Py）2 个期次黄铁矿。其中 Py为成岩期沉积形成，在矿石中分布较少；而 Py与铅锌矿化关系密切，其后生特征明显，可能为 Py重结晶后形成，暗示矿区铅锌矿化与后期热液成矿关系密切。本文通过 LA-ICPMS 原位测试技术对矿床中产出不同期次黄铁矿及闪锌矿微量元素开展测试分析，在总结矿床地质特征的基础上，探讨其成矿过程，厘定矿床成因类型，以期为认识杉树林矿床铅锌成矿作用提供新的依据。分析结果表明，矿床中黄铁矿含多种微量元素，其中 Ag 和 Pb 以显微矿物包裹体的形式赋存。整体上，2 个期次黄铁矿 Co/Ni 比值均远小于 1.00，但值得注意的是，Py中 Cu、Ag、Sb、Pb 含量高于Py25 个数量级，且这些元素均有较大变化范围，暗示该阶段成矿流体中富含铅锌等成矿物质，也说明该矿床铅锌为后生成因。此外，矿区闪锌矿中含有 Cu、Sb、As、Ga、Ge、In 等多种微量元素，类质同象是这些元素主要赋存形式，矿区闪锌矿中相对富集Ge和Ga而亏损In，其Cd/Fe比值均值为6.16，介于0.08300之间，Zn/Cd比值介于 100500 之间，平均值为 223.08，lgRn(Ga/Ge)值为-2.550.47，所对应的成矿温度为 93.7212.6，结合 Frenze 方程计算，成矿温度集中在 197213 之间，表明该矿床成矿温度属于低温范畴。综合矿床地质产出特征与成因判别图解等成果，本研究认为杉树林铅锌矿床属于 MVT 铅锌矿床。关键词关键词：LA-ICP-MS；微量元素特征；成矿信息；矿床成因；杉树林铅锌矿 中图分类号中图分类号：P611;P595 文献标识码文献标识码：A doi:10.16461/ki.1000-4734.2023.43.027 第一第一作者：作者：吴莎，女，1998 年生，硕士研究生，地质学专业.E-mail: Geochemical characteristics of trace elements of sulfides in the Shanshulin Pb-Zn deposit in the Northwestern Guizhou,China WU Sha1,JIN Zhong-guo1,2*,ZHENG Ming-hong2,ZHENG Lun-wei2,LIU Ling2,ZENG Dao-guo3,CAI Guo-sheng3(1.Institute of Resources and Environmental Engineering,Guizhou university,Guiyang 550025,China;2.Guizhou Nonferrous Metal and Nuclear Industry Geological Exploration Bureau,Guiyang 550005,China;3.Academy of Geological and Mineral Exploration,Guizhou Nonferrous Metal and Nuclear Industry Geological Exploration Bureau,Guiyang 550005,China)Abstract:The Shanshulin Pb-Zn deposit is located in the southeastern section of the Weining-Shuicheng metallogenic belt and is a representative Pb-Zn deposit in the northwestern Guizhou metallogenic district.In this paper,based on field observation and microscopic identification,it is identified that there are pyrites of two stages,including the early one(Py)and the late one(Py),in this deposit.The Py was formed in the diagenetic stage of sedimentary rock and is limitedly distributed in the ore,while the Py is closely related to the lead-zinc mineralization with its obviously epigenetic 收稿日期：收稿日期：2022-11-15 基金项目基金项目：贵州省找矿突破战略行动重大协同创新项目（编号：黔科合战略找矿2022ZD004）；国家自然科学基金项目（编号：U1812402）*通讯作者，E-mail: 470 矿 物 学 报 2023 年 characteristics.The Py could be formed by the recrystallization of the Py.It is suggested that the Pb-Zn mineralization is closely related to the late hydrothermal mineralization.In this paper,the LA-ICPMS in-situ testing technology was used to test and analyze trace elements of pyrites and sphalerites of different stages in the deposit.On the basis of summarizing geological characteristics of the deposit,the metallogenic process has been discussed and the genetic type of the deposit has been determined,in order to provide a new basis for understanding the lead-zinc mineralization of the Shanshulin deposit.The results show that pyrites contain various trace elements,among which Ag and Pb occurred in the form of microscopic mineral inclusions.Generally,Co/Ni ratios for pyrites of two stages are far less than 1.00.However,it is worth to notice that contents of Cu,Ag,Sb and Pb of the Py are 2-5 orders of magnitude higher than those of the Py,with large ranges of variation,suggesting that the ore-forming fluid of this stage is rich in ore-forming materials such as lead and zinc,and the deposit is of hydrothermal origin.In addition,sphalerites contain various trace elements such as Cu,Sb,As,Ga,Ge and In which occurred in the form of isomorphism.They are relatively enriched in Ge and Ga,but relatively depleted in In,with Cd/Fe ratios ranging from 0.08 to 300(average 6.16),Zn/Cd ratios varying from 100 to 500(average 223.08),and lg(Ga/Ge)values varying from-2.55 to 0.47 whose corresponding metallogenic temperatures varying from 93.7 to 212.6.Combined with calculated results by using the Frenze equation,the metallogenic temperatures are concentrated in the range of 197213,indicating that the metallogenic temperature of the deposit belongs to the category of low temperature.Based on results of the geological characteristics and interpretations of genetic discrimination diagrams,it is believed that the Shanshulin Pb-Zn deposit belongs to the MVT Pb-Zn deposit.Keywords:LA-ICPMS;characteristics of trace elements;metallogenic information;genesis of mineral deposit;the Shanshulin Pb-Zn deposit 黔西北铅锌成矿区是华南低温成矿域的重要组成部分，区域内铅锌矿沿构造带呈带状分布，主次断裂构造交汇往往是矿床产出部位，断层破碎带及下盘层间破碎带、褶皱虚脱空间是有利储存场所，构造分级控矿特征明显1,2。杉树林铅锌矿床是上世纪 60 年代初贵州省探明的中型矿床，众多学者以该矿床为代表，对黔西北地区铅锌矿床成因3-16、物质来源17-22、控矿因素及成矿规律1-2,4,17-18,20-21,23等开展深入的研究，积累了大量研究成果,为黔西北地区铅锌成矿理论与找矿勘查奠定了理论基础。但由于分析测试手段的限制，目前对于杉树林铅锌矿的矿床成因依然存在较大争议3-16，如吴铁铮3等认为杉树林为层控型铅锌矿床，铅来源于上地幔或与岩浆源有关；陈士杰4等认为矿床严格受地层层位和沉积相的控制，矿体的就位和富化与生物屑、有机质密切相关，矿石保留着可反映沉积特征的层(纹)理构造，是典型的层控型铅锌矿床；郑传仑5认为矿床属于沉积-地下水热液叠加改造的层控铅锌矿床，成矿物质主要来源于赋矿层位下部的下古生界地层；陈国勇16等认为该区域矿床属于叠加（