黔西北青山铅锌矿床黄铁矿微量元素组成特征及其地质意义  

Characteristics of trace element compositions of pyrites in the Qingshan lead-zinc deposit in the northwestern Guizhou and their geological significances

作　　者：吴莎 阮伟玲 金中国 郑明泓 衮民汕 WU Sha;RUAN Wei-ling;JIN Zhong-guo;ZHENG Ming-hong;GUN Min-can(Institute of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China;Non-ferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou,Guiyang 550005,China;Institute of Geology and Mineral Resources Exploration,Non-ferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou,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6期882-893,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);贵州省有色和核工业地质局局管科研项目(编号:GZYSKY2023-2)。

摘　　要：黔西北是川滇黔矿集区重要组成部分,区内铅锌矿床成群成带分布,且多伴生有黄铁矿,但黄铁矿与铅锌成矿作用的关系鲜有人研究,对于深入认识该区铅锌成矿作用是欠缺的。青山铅锌矿床位于威水倒转褶皱背斜右翼,是黔西北地区代表性的中型铅锌矿床,黄铁矿是该矿床主要矿石矿物之一,与闪锌矿伴生。本文通过对该矿床不同类型黄铁矿开展电子探针(EPMA)和激光剥蚀电感耦合等离子质谱仪(LA-ICP-MS)研究,揭示其微量元素组成特征与赋存状态,并探讨其成因和与铅锌成矿关系,为认识该矿床成矿作用提供依据。研究结果表明,该矿床黄铁矿中Fe、S含量略低于理论值,整体显示出亏Fe和S的特征,S/Fe比值小于2,属于硫亏型沉积黄铁矿。矿床中黄铁矿可划分为2期:早期黄铁矿(PyⅠ)相对富集As、Mn、Zn、Ni、Ga、Se、Cd、In、Sn和Tl等元素,其Co/Ni为0.03~0.67(均值0.14,n=30);晚期黄铁矿(PyⅡ)相对富集Pb、Cu、Ag、Mo、Sb等元素,其Co/Ni为0.03~2.54(均值0.41,n=38)。2期黄铁矿中Pb、Sb、As、Co、Ni、Zn、Ge等元素以类质同象形式取代Fe或S进入黄铁矿晶格。野外及镜下鉴定结果表明,青山矿床中两期黄铁矿形成约晚于闪锌矿,但早于方铅矿。本研究认为这2期黄铁矿均为同一热液活动的产物,黄铁矿微量元素组成总体上与川滇黔MVT型铅锌矿床中微量元素较为相似,但由于继承了成岩时期形成的黄铁矿微量元素组成而具沉积型黄铁矿特征。结合矿床产出地质特征,本文认为青山铅锌矿床属于MVT铅锌矿床。The northwestern Guizhou is an important part of the Sichuan-Yunnan-Guizhou ore deposit concentration area,in which lead-zinc deposits are distributed in clusters and zones.There are associated pyrite in most of those lead-zinc deposits.However,the relationship between pyrite and the lead-zinc mineralization has been rarely studied.It is insufficient to deeply understand the lead-zinc mineralization in this area.The Qingshan lead-zinc deposit,located in the right limb of the Weishui inverted fold anticline,is a representative medium-sized lead-zinc deposit in the northwestern Guizhou.Pyrite is one of the main ore minerals in the deposit.It is generally associated with sphalerite.In this paper,the electron probe(EPMA)and laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS)are used to have analyzed different types of pyrites in this deposit,in order to reveal compositional characteristics and occurrence states of trace elements in pyrites,and to discuss the genesis of pyrite and its relationship with the lead-zinc mineralization,and then to provide a basis for understanding the Pb-Zn mineralization of this deposit.The results show that contents of Fe and S in pyrites of the deposit are slightly lower than theoretical values of Fe and S in pyrite.Pyrites of the deposit have characteristics of generally depleted Fe and S.Their S/Fe ratios are less than 2.Thus,they belong to the sulfur deficit type sedimentary pyrite.Two stages of pyrites in the deposit have been identified.The early-stage pyrite(PyⅠ)is relatively rich in As,Mn,Zn,Ni,Ga,Se,Cd,In,Sn and Tl,with its Co/Ni ratios ranging from 0.03 to 0.67(mean 0.14,n=30).The late-stage pyrite(PyⅡ)is relatively rich in Pb,Cu,Ag,Mo,Sb and other elements,with its Co/Ni ratios ranging from 0.03 to 2.54(mean 0.41,n=38).Pb,Sb,As,Co,Ni,Zn,Ge and other elements occurred in the form of isomorphism for substituting Fe or S in lattice of two stages of pyrites.Field observation and microscopic identification results show that the formation of pyrites of two sta

关 键 词：EPMA LA-ICPMS 微量元素特征 成矿信息 矿床成因 青山铅锌矿床 

分 类 号：P595[天文地球—地球化学]