黔西北杉树林铅锌矿床硫化物微量元素地球化学特征  

Geochemical characteristics of trace elements of sulfides in the Shanshulin Pb-Zn deposit in the Northwestern Guizhou,China

作　　者：吴莎 金中国 郑明泓 张伦尉 刘玲 曾道国 蔡国盛 WU Sha;JIN Zhong-guo;ZHENG Ming-hong;ZHENG Lun-wei;LIU Ling;ZENG Dao-guo;CAI Guo-sheng(Institute of Resources and Environmental Engineering,Guizhou university,Guiyang 550025,China;Guizhou Nonferrous Metal and Nuclear Industry Geological Exploration Bureau,Guiyang 550005,China;Academy of Geological and Mineral Exploration,Guizhou Nonferrous Metal and Nuclear Industry Geological Exploration Bureau,Guiyang 550005,China)

机构地区：[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

出　　处：《矿物学报》2023年第4期469-480,共12页Acta Mineralogica Sinica

基　　金：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[2022]ZD004);国家自然科学基金项目(编号:U1812402)。

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(PyⅠ)和晚期(PyⅡ)2个期次黄铁矿。其中PyⅠ为成岩期沉积形成,在矿石中分布较少;而PyⅡ与铅锌矿化关系密切,其后生特征明显,可能为PyⅠ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,PyⅡ中Cu、Ag、Sb、Pb含量高于PyⅠ2~5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0.08~300之间,Zn/Cd比值介于100~500之间,平均值为223.08,lg Rn(Ga/Ge)值为-2.55~0.47,所对应的成矿温度为93.7~212.6℃,结合Frenze方程计算,成矿温度集中在197~213℃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。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(Pyl)and the late one(Pyl),in this deposit.The Pyl was formed in the diagenetic stage of sedimentary rock and is limitedly distributed in the ore,while the Pyll is closely related to the lead-zinc mineralization with its obviously epigenetic characteristics.The Pyll could be formed by the recrystallization of the Pyl.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 1.0o.However,it is worth to notice that contents of Cu,Ag,Sb and Pb of the Pyll are 2-5 orders of magnitude higher than those of the Pyl,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/

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 

分 类 号：P611[天文地球—矿床学] P595[天文地球—地质学]