特提斯喜马拉雅东段扎西康矿集区姐纳各普金矿床成因:黄铁矿He-Ar及原位S同位素约束  

Genesis of Jienagepu Gold Deposit in Zhaxikang Ore Concentration Area, Eastern Tethys Himalayas: Constraints from He-Ar and In-Situ S Isotope of Pyrite

作　　者：李洪梁 李光明[2,3] 张志[2] 张林奎[2] 董随亮[2] 卿成实[2] 李应栩[2] Li Hongliang;Li Guangming;Zhang Zhi;Zhang Linkui;Dong Suiliang;Qing Chengshi;Li Yingxu(Institute of Prospecting Technology,Chinese Academy of Geological Sciences,Chengdu 611734,China;Chengdu Center of China Geological Survey,Chengdu 610081,China;College of Earth Science,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]中国地质科学院探矿工艺研究所,四川成都611734 [2]中国地质调查局成都地质调查中心,四川成都610081 [3]成都理工大学地球科学学院,四川成都610059

出　　处：《地球科学》2021年第12期4291-4315,共25页Earth Science

基　　金：中国地质调查局项目(Nos.DD20190644,DD20190147);国家自然科学基金项目(Nos.91955208,41702080,41602214,41807300);国家科学技术部科技支撑计划重点项目(Nos.2016YFC060308,2018YFC0604103);第二次青藏高原综合科学考察研究(No.2019QZKK0902)。

摘　　要：姐纳各普金矿床是特提斯喜马拉雅东段扎西康矿集区内新近发现的中新世热液金矿床,但其成因认识较为模糊.矿体呈层状或似层状,严格受伸展断裂构造控制,具蚀变岩型和石英脉型2种矿石,主要发育硅化、黄铁矿化、绢云母化和方解石化.为厘定矿床成因,对矿床Ⅱ号和Ⅲ号矿体中的蚀变岩型矿石进行了系统采样,分析其黄铁矿He-Ar和原位S同位素组成特征.结果表明:黄铁矿内的4He含量介于0.038×10-7~0.446×10^(-7)cm^(3)STP/g,平均含量0.200×10^(-7)cm^(3)STP/g;3He/4He比值介于0.08~0.09 Ra,平均比值为0.08 Ra;^(40)Ar含量变化于0.049×10^(-7)~0.132×10^(-7)cm^(3)STP/g,平均含量0.084×10^(-7)cm^(3)STP/g;^(40)Ar/36Ar比值介于308.0~386.3,平均比值347.1,指示成矿流体主要来自壳源变质流体;黄铁矿δ34S值分布集中,总体变化于1‰~3‰,平均值2.98‰,显示成矿物质来自地壳深部壳幔物质均一化的深源.结合前人研究成果,文章认为姐纳各普金矿床属于造山型金矿床,其成因的厘定对丰富和完善大陆碰撞造山成矿作用理论和指导区域矿床勘查具有重要意义.Jienagepu gold deposit is a newly discovered Miocene hydrothermal gold deposit in the Zhaxikang ore concentration area,eastern Tethyan Himalayas,but its genesis is rather vague.The ore body is stratified or approximately stratified,strictly controlled by extensional fault structure.In this study,two types of ores were recognized,namely altered rock type and quartz vein type,with extensive hydrothermal alternation,including silicification,pyritization,sericization and calcite.Samples were systematically taken from the altered rock type ore in orebody No.Ⅱand No.Ⅲ,and the composition characteristics of He-Ar and in-situ S isotope of pyrite were analyzed to determine the genesis of the deposit.The results show that the content of 4He and3He/4He ratio in pyrite ranged widely from 0.038×10^(-7)cm^(3)STP/g to 0.446×10^(-7)cm^(3)STP/g,0.08 Ra to 0.09 Ra,with an average of 0.200×10^(-7)cm^(3)STP/g and 0.08 Ra.The content of ^(40)Ar and ^(40)Ar/^(36)Ar ratio vary from 0.049×10^(-7)cm^(3)STP/g to0.132×10^(-7)cm^(3)STP/g,308.0 to 386.3,with an average of 0.084×10^(-7)cm^(3)STP/g and 347.1,indicating that the ore-forming fluid mainly originated from the crustal metamorphic fluid.Theδ^(34)S value of pyrite is concentrated,and the overall variation is between 1‰and 3‰,with an average of 2.98‰,showing that the ore-forming material is from crustal-mantle homogenized deep source.Combined with previous research results,in this paper it holds that Jienagepu gold deposit is an orogenic type gold deposit,and the determination of genesis is of great significance to enrich and perfect the mineralization theory of continental collisional orogeny and to guide the exploration of regional ore deposits.

关 键 词：造山型金矿床 HE-AR同位素 原位S同位素 姐纳各普 扎西康矿集区 特提斯喜马拉雅 矿床 

分 类 号：P618.51[天文地球—矿床学]