大兴安岭北段斑岩型钼(铜)矿床主要硫化物化学成分特征及地质意义--以770钼(铜)矿床为例  

Chemical characteristics of major sulfides in porphyry-type molybdenum(copper)deposits in the Northern Greater Khingan Mountains and their geological significance--A case study of 770 Molybdenum(Copper)Deposit

作　　者：孙永刚 靳皇玉 王永胜[2] 张徐平 王成昆 李焕纪 Sun Yonggang;Jin Huangyu;Wang Yongsheng;Zhang Xuping;Wang Chengkun;Li Huanji(School of Resources and Civil Engineering,Suzhou University;Geological Survey Institute of Jilin Province;The Eleventh Geological Survey Institute of Heilongjiang Province)

机构地区：[1]宿州学院资源与土木工程学院 [2]吉林省地质调查院 [3]黑龙江省第十一地质勘查院

出　　处：《黄金》2024年第11期27-33,共7页Gold

基　　金：2024年度安徽省教育厅高校自然科学重点科研项目(2024AH051826);宿州学院2022年博士科研启动基金项目(2022BSK009);宿州学院2023年博士后科研启动基金项目(2023BSH001);中国矿产地质志项目(DD20221695,DD20190379,DD20160346)。

摘　　要：斑岩型钼(铜)矿床一直以来都是地质学领域的研究热点。770钼(铜)矿床是近年来在大兴安岭北段新发现的斑岩型钼(铜)矿床,目前对于该矿床的报道较少。以大兴安岭北段770钼(铜)矿床中黄铁矿和黄铜矿为研究对象,利用电子显微镜和电子探针分析技术(EPMA),深入探讨黄铁矿和黄铜矿的晶体形态和主量元素、微量元素组成,以便更全面地解析黄铁矿和黄铜矿的化学成分特征及其地质意义。770钼(铜)矿床为大型斑岩型钼(铜)矿床,矿体赋存于晚侏罗世的花岗斑岩中。从中心向外部,蚀变区域可分为钾化带和黄铁-绢英岩化带。电子探针分析结果显示,黄铁矿中w(S)普遍小于53.45%,w(Fe)普遍小于46.55%,w(S)/w(Fe)≥1.148,表明770钼(铜)矿床黄铁矿主要为贫铁贫硫型黄铁矿,成矿环境的硫逸度较高。黄铁矿微量元素与主量元素的正负相关性特征表明,黄铁矿中的微量元素如Zn、Mo、Ni、Co和As,通常以矿物包裹体或类质同象的形式存在于矿物中。770钼(铜)矿床中黄铁矿w(Co)/w(Ni)值(2.25~4.50)显示,其具有岩浆热液成因的性质。黄铜矿的[n(Cu)+n(Fe)]/n(S)值(平均值为0.91)表明,黄铜矿等金属硫化物的形成可能发生在中低温(约200℃)热液环境中。Porphyry-type molybdenum(copper)deposits have long been a focus of geological studies.770 Molybdenum(Copper)Deposit,a newly discovered porphyry-type deposit in the Northern Greater Khingan Mountains,has seen limited reporting.This study examines pyrite and chalcopyrite within 770 Molybdenum(Copper)Deposit using electron microscopy and EPMA(Electron Probe Micro-analysis)to investigate the crystal morphology and the major and trace element compositions of these sulfides,providing a comprehensive understanding of their chemical characteristics and geological significance.The 770 Molybdenum(Copper)Deposit,a large porphyry-type molybdenum(copper)deposit,has its ore bodies hosted in Late Jurassic granite porphyry.Alteration zones are divided into a central potassic zone and a peripheral pyrite-sericite zone.EPMA results show pyrite with sulfur content generally below 53.45%,iron content below 46.55%,and a w(S)/w(Fe)ratio≥1.148,indicating that the deposit s pyrite is low-iron,low-sulfur pyrite,formed under conditions of high sulfur fugacity.The trace-to-major element correlations suggest elements like Zn,Mo,Ni,Co,and As exist in pyrite as mineral inclusions or in isomorphic forms.The w(Co)/w(Ni)ratio(2.25-4.50)in pyrite indicates a magmatic-hydrothermal origin,while the[n(Cu)+n(Fe)]/n(S)ratio in chalcopyrite(average 0.91)suggests formation in a mid-to low-temperature(around 200℃)hydrothermal environment.

关 键 词：大兴安岭北段 斑岩型 770钼(铜)矿床 黄铁矿 黄铜矿 微量元素 岩浆热液 

分 类 号：TD11[矿业工程—矿山地质测量] P618.52[天文地球—矿床学]