云南毛坪铅锌矿床新发现Ⅵ号矿带硫化物稀散元素富集特征及其地质意义  

Enrichment characteristics and its geological significance of dispersed elements within sulfide minerals from the Ⅵ ore belt in the Maoping Pb-Zn deposit,Yunnan Province,China

作　　者：何叶 周高明 钟华 程涌 岳正鹏 刘和松[1] 周家喜 HE Ye;ZHOU GaoMing;ZHONG Hua;CHENG Yong;YUE ZhengPeng;LIU HeSong;ZHOU JiaXi(Key Laboratory of Critical Minerals Metallogeny in Universities of Yunnan Province,School of Earth Sciences,Yunnan University,Kunming 650500,China;Yunnan Key Laboratory of Sanjiang Metallogeny and Resources Exploration&Utilization,Yunnan University,Kunming 650500,China;MNR Key Laboratory of Sanjiang Metallogeny and Resources Exploration&Utilization,Yunnan University,Kunming 650500,China;Yiliang Chihong Mining Co.Ltd.,Zhaotong 657600,China;Faculty of Metallurgy and Mining Engineering,Kunming Metallurgy College,Kunming 650033,China)

机构地区：[1]云南大学地球科学学院,云南省高校关键矿产成矿学重点实验室,昆明650500 [2]云南大学,云南省三江成矿作用及资源勘查利用重点实验室,昆明650500 [3]云南大学,自然资源部三江成矿作用及资源勘查利用重点实验室,昆明650500 [4]彝良驰宏矿业有限公司,昭通657600 [5]昆明冶金高等专科学校冶金与矿业学院,昆明650033

出　　处：《岩石学报》2023年第10期2985-3001,共17页Acta Petrologica Sinica

基　　金：云南省新一轮找矿突破战略行动地质勘查基金科研项目(Y202303);国家自然科学基金项目(92162218、42002086);云南大学科研启动项目(YJRC4201804)和云南大学关键金属成矿与找矿预测创新团队项目(2021-3)联合资助。

摘　　要：作为华南大面积低温成矿域的重要组成部分,川滇黔铅锌矿集区是我国重要的铅锌银等资源基地之一,同时该矿集区也是Ge、Cd、Ga和In等稀散元素的超常富集区域。毛坪矿床是该矿集区内第二大铅锌矿床,累计探明铅锌金属储量超过3Mt(Pb+Zn平均品位≥18%),锗(Ge)保有储量182t。本文以新发现的Ⅵ矿带(铅锌金属已探明储量≥60万t,Pb+Zn平均品位≥20%)为研究对象,利用LA-ICPMS对主要矿石矿物闪锌矿和黄铁矿进行了微区原位微量元素组成和Mapping分析。研究结果显示Ⅵ矿带闪锌矿普遍富集Ge(最高580×10^(-6),均值81.1×10^(-6))、Cd(最高3486×10^(-6),均值1613×10^(-6))和Ga(最高190×10^(-6),均值44.4×10^(-6));黄铁矿普遍富集Mn、As、Pb、Cu、Ag和Sb。与Ⅰ和Ⅱ号矿带闪锌矿相比,Ⅵ号矿带闪锌矿更富集Ge和Ga。闪锌矿中Fe和Pb以类质同象为主,偶见黄铁矿和方铅矿显微包体;Cu、Ge、Ag和As赋存形式主要为类质同象,替代方式为Ge^(4+)+2(Cu+,Ag+,As+)↔3Zn^(2+);Cd以类质同象方式赋存为主,替代机制为Cd^(2+)↔Zn^(2+);Ga和In可能主要以类质同象方式存在。黄铁矿中Pb和Mn主要以方铅矿和碳酸盐矿物显微包体为主;Cu、As和Sb以类质同象形式存在于黄铁矿中;Ag和Zn可能以独立矿物形式赋存;Co和Ni以类质同象方式替代Fe进入黄铁矿晶格中,替代方式为Ni^(2+)+Co^(2+)↔2Fe^(2+)。毛坪矿床新发现Ⅵ矿带硫化物相比典型MVT矿床硫化物具有不同的In和Ge含量以及Cd/Fe比值,结合矿床地质特征和其他证据,表明毛坪矿床成因类型特殊,有别于经典MVT铅锌矿床,属于川滇黔型铅锌矿床。As an important part of the large-scale low-temperature mineralization area in South China,the Sichuan-Yunnan-Guizhou(SYG)Pb-Zn metallogenic province is one of the most important bases for the Pb,Zn,Ag and other resources in China.At the same time,this province is also an area of anomalous enrichment of dispersed elements such as Ge,Cd,Ga and In.The Maoping deposit is the second largest Pb-Zn deposit in this province,with a cumulative proven metal reserve of over 3Mt Pb+Zn(averaged grade≥18%)and 182t germanium(Ge).In this paper,the newly discovered Ⅵ ore belt(with a total proven metal reserve of Pb+Zn≥0.6Mt with averaged grade of Pb+Zn≥20%)in the deposit is taken as the research object to carry out an in-situ trace element composition and mapping analysis upon its main ore minerals(sphalerite and pyrite)by using LA-ICPMS method.The results show that Ge(max 580×10^(-6),mean 81.1×10^(-6)),Cd(max 3486×10^(-6),mean 1613×10^(-6))and Ga(max 190×10^(-6),mean 44.4×10^(-6))are generally enriched in the sphalerite,while Mn,As,Pb,Cu,Ag and Sb are generally enriched in the pyrite,indicating that the sphalerite is the main carrier mineral for dispersed elements enrichment.In addition,compared with the sphalerites from the No.Ⅰ and No.Ⅱ ore belts,those from theⅥore belt are more enriched in Ge and Ga.Moreover,the Fe and Pb in the sphalerite of this ore belt are mainly isomorphous with similar quality,and micro-inclusions of pyrite and galena are occasionally observed;the main occurrence forms of Cu,Ge,Ag and As are isomorphous substitution,i.e.,Ge^(4+)+2(Cu^(+),Ag^(+),As^(+))↔3Zn^(2+);Cd enters sphalerite in an isomorphic way,and the replacement mechanism is Cd^(2+)↔Zn^(2+);Ga and In may exist in sphalerite as an isomorphic manner.The Pb and Mn in the pyrite are mainly occurred as microinclusions of the galena and carbonate minerals;the Cu,As and Sb exist in pyrite as a homomorphic form;the Co and Ni enter the pyrite lattice in an isomorphic way instead of Fe,i.e.,Ni^(2+)+Co^(2+)↔2Fe^(2+);while the Ag

关 键 词：硫化物 微量元素 稀散元素 LA-ICPMS 毛坪铅锌矿床 川滇黔型铅锌矿床 

分 类 号：P612[天文地球—矿床学] P618.7[天文地球—地质学]