滇东北火德红MVT矿床中铊的差异性富集机制:来自EBSD、LA-ICPMS和TEM证据  

The differential enrichment mechanism of thallium in the Huodehong MVT deposit,NE Yunnan Province,China:Evidence from EBSD,LA-ICPMS and TEM

作　　者：姜永果[1,2,3] 周家喜 罗开 徐畅 黄智龙[5] 杨昌华[3] 金中国 JIANG YongGuo;ZHOU JiaXi;LUO Kai;XU Chang;HUANG ZhiLong;YANG ChangHua;JIN ZhongGuo(Faculty of Land Resource Engineering,Kunming University of Science and Technology,Kunming 650093,China;Key Laboratory of Critical Minerals Metallogeny in Universities of Yunnan Province,School of Earth Sciences,Yunnan University,Kunming 650500,China;Institute of Geology,Geophysics and Geochemistry Exploration,Yunnan Nonferrous Geological Bureau,Kunming 650216,China;School of Earth Sciences,China University of Geosciences,Wuhan 430074,China;Stake Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;Nonferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou,Guiyang 550005,China)

机构地区：[1]昆明理工大学国土资源工程学院,昆明650093 [2]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 [3]云南省有色地质局,地质地球物理化学勘查院,昆明650216 [4]中国地质大学(武汉)地球科学学院,武汉430074 [5]中国科学院地球化学研究所,矿床地球化学国家重点实验室,贵阳550081 [6]贵州省有色金属和核工业地质勘查局,贵阳550005

出　　处：《岩石学报》2023年第10期3002-3014,共13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);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：铊(Tl)是一种战略性关键金属,在高科技领域具有重要用途。作为“稀散元素”之一,Tl主要富集于低温贱金属硫化物矿床中,黄铁矿和白铁矿是其主要载体矿物。滇东北火德红MVT铅锌矿床中黄铁矿和白铁矿显示Tl的富集,其中白铁矿中Tl含量显著高于黄铁矿,为探究Tl在不同矿物之间的差异性富集机制提供了理想对象。本文对火德红矿床共生黄铁矿-白铁矿开展系统的结晶学、矿物学和地球化学研究。电子背散射衍射(EBSD)结果表明,热液黄铁矿、白铁矿晶粒组构具有一定继承性,与闪锌矿紧密共生,暗示为同一成矿事件的产物。激光剥蚀耦合等离子体质谱(LA-ICPMS)原位微量元素含量分析结果显示,黄铁矿和白铁矿中的Tl含量分别为127×10^(-6)~516×10^(-6)和356×10^(-6)~1046×10^(-6),不同含量测点Tl的激光剥蚀时间分辨元素信号曲线均较为平滑,暗示Tl主要以类质同象形式进入黄铁矿和白铁矿晶格。透射电镜(TEM)进一步证实Tl类质同象直接替换Fe为主,即2Tl^(+)←→□(空位)+Fe^(2+)。结合黄铁矿和白铁矿中Tl与Zn含量的正相关关系,本文认为白铁矿中Tl的超常富集可能与偏酸性条件下富Tl、Zn和Fe等金属成矿流体有关。综合研究表明,火德红矿床黄铁矿与白铁矿中Tl的差异性富集与晶体结构、Tl赋存状态无关,而是流体成分、物化条件共同制约的结果,受到矿物和矿床等不同尺度苛刻成矿条件的影响。与闪锌矿共生的白铁矿是未来寻找铊资源的重要方向。Thallium(Tl)is a critical metal with important applications in the high-tech industry,and mainly used as by-product of base metal sulfides.As one of the dispersed elements,Tl is mainly enriched in low-temperature base metal sulfide deposits,with pyrite and marcasite as its main carrier.The Huodehong MVT Pb-Zn deposit in Yunnan Province shows an abnormal enrichment of Tl,and the concentration of Tl in marcasite is significantly higher than that in co-existing pyrite.To investigate the differential enrichment mechanism of Tl among different minerals,this paper carried out systematic crystallography,mineralogy,and geochemistry studies on the pyrite-marcasite association from the Huodehong deposit.The electron backscatter diffraction(EBSD)results indicate that the grain structure of hydrothermal pyrite and marcasite has a certain inheritance,closely coexisting with sphalerite,suggesting that they are products of the same mineralization event.The in situ trace element content analysis results of laser ablation coupled plasma mass spectrometry(LA-ICPMS)show that the Tl content in pyrite and marcasite is 127×10^(-6)~516×10^(-6) and 356×10^(-6)~1046×10^(-6),respectively,the time resolved element signal curves of Tl are relatively smooth,suggesting that Tl mainly enters the lattice of pyrite and marcasite in the lattice.Transmission electron microscopy(TEM)further confirms that Tl directly replaces Fe,i.e.,2Tl^(+)←→□(vacancy)+Fe^(2+).Combined with the positive correlation between Tl and Zn content in pyrite and marcasite,this paper suggests that the abnormal enrichment of Tl in marcasite may be related to the ore-forming fluid rich in Tl,Zn and Fe under slightly acidic conditions.Comprehensive research shows that the differential enrichment of Tl in pyrite and marcasite of Huodehong deposit is not related to the crystal structure and the occurrence of Tl,but is the result of the joint constraints of fluid composition,physicochemical condition,and is affected by metallogenic conditions of different scales.Marcasi

关 键 词：铊 赋存状态 差异性富集 白铁矿 火德红MVT矿床 

分 类 号：P585.2[天文地球—岩石学] P612[天文地球—地质学] P618.88