湘西大脑坡超大型铅锌矿床黄铁矿原位微量元素研究  

In situ trace element study of pyrites from the Danaopo super-large Pb-Zn deposit in the western Hunan,China

作　　者：吴涛 黄智龙[1] 向震中 叶霖[1] 隋志恒 胡宇思 严再飞[1] WU Tao;HUANG Zhi-long;XIANG Zhen-zhong;YE Lin;SUI Zhi-heng;HU Yu-si;YAN Zai-fei(State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;University of Chinese Academy of Sciences,Beijing 100049,China;405 Geological Prospecting Party,Bureau of Geology and Mineral Exploration and Development of Hunan Province,Jishou 416099,China)

机构地区：[1]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,贵州贵阳550081 [2]中国科学院大学,北京100049 [3]湖南省地质矿产开发局405队,湖南吉首416099

出　　处：《矿物学报》2020年第4期430-440,共11页Acta Mineralogica Sinica

基　　金：国家自然科学基金项目(编号:U1812402,41673056)。

摘　　要：大脑坡铅锌矿床位于鄂西—湘西—黔东铅锌成矿域的中部,是近年来花垣矿田内新发现的又一超大型铅锌矿床。前人对花垣矿田内铅锌矿床的研究获得了较多的认识,但是关于区内铅锌矿床的成因类型一直备受争议。本文以大脑坡铅锌矿床不同标高的成矿期黄铁矿为研究对象,通过LA-ICP-MS原位点测试和元素Mapping分析,旨在揭示黄铁矿中不同微量元素的赋存状态以及为矿床成因提供新的约束。结果表明,该矿床黄铁矿所含微量元素种类较少且含量偏低,指示其形成于相对低温的环境,相较而言,黄铁矿较富集Co、Ni、As、Mn、Cu、Pb和Zn等元素,其中Co、As、Ni、Sb和Ge等元素主要是以类质同象的方式赋存于黄铁矿的晶格之中,大部分的Zn和Pb分别以闪锌矿微米级包裹体和方铅矿微/纳米级包裹体的形式赋存于黄铁矿中,而Cd、Mn和Cu、Ag则以类质同像的方式分别赋存于闪锌矿和方铅矿的晶格中。此外,黄铁矿的Co/Ni(均值1.0),Zn/Ni(均值42.0)和Cu/Ni(均值3.5)比值均指示其为热液型的黄铁矿。总体而言,大脑坡矿床黄铁矿微量元素特征可与典型MVT型铅锌矿床类比,在Co-Ni含量投影图上,样品点与MVT型矿床投影区高度吻合。结合矿床地质地球化学和黄铁矿微量元素特征,我们认为大脑坡矿床属于MVT型铅锌矿床。The Danaopo Pb-Zn deposit,located in the central part of the Western Hubei-Western Hunan-Eastern Guizhou metallogenic province,is a newly discovered super-large deposit in the Huayuan orefield.Although previous studies have obtained a lot of understandings on Pb-Zn deposits in the Huayuan region,the genetic types of Pb-Zn deposits in this area have been debated for a long time.In this paper,we have selected pyrites from ores at different elevations of the Danaopo deposit for the LA-ICP-MS in-situ point test and element mapping analysis,in order to reveal the occurrence states of various trace elements in pyrites and to provide new constraints for the genesis of the deposit.The analytical results show that these pyrites contain a few types and low contents of trace elements,indicating that they were formed in a relatively low-temperature environment.Comparatively,these pyrites are relatively rich in Co,Ni,As,Mn,Cu,Pb,and Zn.Especially,Co,Ni,As,Sb,and Ge occurred mainly in the pyrite lattice in the form of isomorphism.Most of the Zn and Pb occurred as sphalerite micro-inclusions and galena micro-/nano-particles in the pyrites,whereas the Cd,Mn,and Cu,Ag occurred as isomorphous substitution in the lattices of sphalerite and galena,respectively.In addition,the Co/Ni(mean=1.0),Zn/Ni(mean=42.0),and Cu/Ni(mean=3.5)ratios suggest that these pyrites are hydrothermal ones.Generally,features of trace elements in pyrites from the Danaopo deposit are similar to those of typical MVT type Pb-Zn deposits as pyrite samples are mostly plotted into the projection field of MVT type deposit on the diagram of Co-Ni contents.Hence,combined with the geological and geochemical characteristics of the deposit as well as the trace elements of pyrites,we have suggested that the Danaopo deposit belongs to the MVT type Pb-Zn deposit.

关 键 词：大脑坡铅锌矿床 黄铁矿 原位微量元素 MVT型矿床 LA-ICP-MS 

分 类 号：P579[天文地球—矿物学] P618[天文地球—地质学]