东昆仑驼路沟钴金矿床中黄铁矿的结构和成分特征及其对钴成矿作用的启示  

Textural and Compositional Characteristics of Pyrite in the Tuolugou Cobalt-gold Deposit in East Kunlun and Its Implications for Cobalt Mineralization

作　　者：冯浩东 邹少浩 许德如 陈喜连 王华 FENG Haodong;ZOU Shaohao;XU Deru;CHEN Xilian;WANG Hua(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;School of Earth Sciences,East China University of Technology,Nanchang 330013,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [2]东华理工大学地球科学学院,江西南昌330013

出　　处：《东华理工大学学报（自然科学版）》2024年第2期131-145,共15页Journal of East China University of Technology(Natural Science)

基　　金：国家自然科学基金项目(U2344205,42002089,41930428);江西省自然科学基金项目(20224BAB213040,20224BAB203036,20224ACB203008)。

摘　　要：驼路沟钴金矿床是我国少见的大型热液型矿床。为了深入认识该矿床(含)钴成矿过程,选取驼路沟矿床中的富钴黄铁矿为研究对象,通过岩相学、矿物学、微量元素特征和S同位素组成分析,确定黄铁矿结构、成矿流体特征、演化过程及成矿物质来源,进而揭示详细的成矿过程,以及黄铁矿对钴成矿的指示作用。研究表明,驼路沟含钴黄铁矿可分成三部分:晶型较好、偶见孔隙的黄铁矿核部;具有震荡环带,与硫镍钴矿、辉砷镍矿共生的黄铁矿幔部;晶型较好的黄铁矿边部。其中,黄铁矿核部富集Co、Ni等元素,幔部富集Co、Ni、As等元素,边部具有较高的As、Se含量和稍高的Au含量。三者对比显示,核部Co含量最高,幔部As含量最高,边部含有较高的Au,三者ω(Co)/ω(Ni)值绝大部分都大于1,指示其热液成因;从核部到幔部再到边部,Co、Ni含量逐渐降低,Se含量逐渐升高,说明其流体温度逐渐降低;黄铁矿中δ^(34)S值整体为-1.43‰~0.48‰,说明成矿物质主要来源于岩浆。黄铁矿的结构、微量元素特征、S同位素组成表明,驼路沟的成矿流体为富含Co、Ni、As等元素的低温热液流体。本研究对于揭示喷流热液型钴矿床成矿过程及指导类似矿床的找矿勘查具有重大意义。The Tuolugou cobalt gold deposit is a rare large-scale hydrothermal type independent cobalt deposit in China.Few previous studies are focused on the cobalt-bearing minerals in this deposit,which hinder the further understanding of the mineralization process.To address this problem,detailed petrography,mineral assemblage,pyrite textural,trace elements,and S isotopic composition analyses are conducted in the Tuolugou deposit in order to reveal the characteristics of ore-forming fluid,evolution process,source of ore-forming material,and ore-forming process,and the indicative role of pyrite in cobalt mineralization is explained.The Tuolugou cobalt-bearing pyrite can be divided into three generations:the core with good crystal shape and occasional pores,the mantle with an oscillating ring and symbiosis with thionickelite and arsonite,and the well-crystallized pyrite rim.Among them,the pyrite core is rich in Co,Ni and other elements,the mantle is rich in Co,Ni and As,and the rim has higher As and Se content and slightly higher Au content.Comparisons of the three generations of pyrite show that the core has the highest Co content,the mantle has the high As content,and the edge contains high Au content.Theω(Co)/ω(Ni)ratios in the three generations of pyrite are mostly greater than 1,indicating the hydrothermal origin.From the core to the mantle to the rim,the Co and Ni contents gradually decrease,and the Se content gradually increases,which indicates the fluid temperature gradually decreases.Theδ^(34)S value of pyrite is-1.43‰~0.48‰,which indicates that the ore-forming material mainly comes from magma.The textural,trace element characteristics and S isotope composition of the pyrite show that the ore-forming fluid is a low-temperature hydrothermal fluid rich in Co,Ni,As and other elements.This study is of great significance for revealing the mineralization process of sedimentary exhalative and hydrothermal reworking cobalt deposit and guiding the prospecting of similar deposits.

关 键 词：黄铁矿 微量元素 S同位素 驼路沟钴金矿床 

分 类 号：P611[天文地球—矿床学]