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

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 cm3 STP/g，平均含量0.200×10-7 cm3 STP/g；3He/4He比值介于0.08~0.09 Ra，平均比值为0.08 Ra；40Ar含量变化于0.049×10-7~0.132×10-7 cm3 STP/g，平均含量0.084×10-7 cm3 STP/g；40Ar/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. 

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

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. Ⅱ and 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 and 3He/4He ratio in pyrite ranged widely from 0.038×10-7 cm3 STP/g to 0.446×10-7 cm3 STP/g, 0.08 Ra to 0.09 Ra, with an average of 0.200×10-7 cm3 STP/g and 0.08 Ra. The content of 40Ar and 40Ar/36Ar ratio vary from 0.049×10-7 cm3 STP/g to 0.132×10-7 cm3 STP/g, 308.0 to 386.3, with an average of 0.084×10-7 cm3 STP/g and 347.1, indicating that the ore-forming fluid mainly originated from the crustal metamorphic fluid. The δ34S 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.