东昆仑造山带岩浆Ni-Co硫化物矿床成矿作用:橄榄石成分和全岩S同位素制约  

The formation of magmatic Ni-Co sulfide deposits in the East Kunlun Orogen:Constraints from geochemical compositions of olivine and whole-rock S isotopic data

作　　者：陈文[1,2] 陈列锰 于宋月[2] 李大鹏 吴树宽[2,4] 王治安[4] CHEN Wen;CHEN LieMeng;YU SongYue;LI DaPeng;WU ShuKuan;WANG ZhiAn(School of Earth Science and Resources,China University of Geosciences(Beijing),Beijing 100083,China;State Key Laboratory for Critical Mineral Research and Exploration,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;The Fifth Geological Exploration Institute of Qinghai Province,Xining 810013,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国科学院地球化学研究所,关键矿产成矿与预测全国重点实验室,贵阳550081 [3]东华理工大学核资源与环境国家重点实验室,南昌330013 [4]青海省第五地质勘查院,西宁810013

出　　处：《岩石学报》2025年第2期453-475,共23页Acta Petrologica Sinica

基　　金：中国科学院前瞻战略科技先导专项(XDA0430303);国家自然科学基金项目(42173020);国家重点研发计划(2023YFF0804403、2022YFC2903501);第二次青藏高原综合科学考察研究(2019QZKK0801)联合资助.

摘　　要：东昆仑造山带不仅产出世界级夏日哈木Ni-Co硫化物矿床,也产出多个同时代的含岩浆硫化物的镁铁-超镁铁质岩体,如石头坑德。夏日哈木和石头坑德岩体具有相似的矿物学和岩石学特征,但二者的成矿规模明显不同,这些异同点为探讨造山带环境幔源岩浆的硫饱和机制与过程、以及岩浆硫化物成矿控制因素提供了良好的对象。本文在前人研究的基础上,系统分析与对比夏日哈木和石头坑德岩体的橄榄石成分和全岩S同位素组成,探讨造山带环境岩浆硫化物矿床的成矿作用。夏日哈木岩体中橄榄石的Fo牌号在82.3~90.0之间,Ni含量在558×10^(-6)~4370×10^(-6)之间;石头坑德岩体中橄榄石的Fo牌号在79.9~90.2之间,Ni含量在300×10^(-6)~3040×10^(-6)之间。夏日哈木岩体全岩的δ^(34) S值在4.0‰~6.4‰之间,平均值为5.2‰;石头坑德岩体全岩的δ^(34) S值在1.8‰~4.6‰之间,平均值为3.2‰。夏日哈木岩体中高Fo牌号橄榄石的Ni含量(高达4000×10^(-6))明显高于石头坑德岩体(通常小于3000×10^(-6)),表明前者母岩浆的Ni含量高于后者。石头坑德岩体贫硫化物纯橄岩中橄榄石具有高的Fo牌号和低的Ni含量,且显示出负相关性。这些特征表明石头坑德岩体母岩浆演化过程经历了富Mg碳酸盐岩的混染:富Mg物质的加入不仅促使结晶出高Fo牌号的橄榄石,也延长了橄榄石的结晶区间。由于Ni在橄榄石中为中等相容元素,大量橄榄石的结晶导致残余岩浆中的Ni含量进一步降低。此外,岩相学研究表明夏日哈木岩体中包裹硫化物珠滴的橄榄石Fo牌号较高,最高值达89.2;相反,石头坑德岩体中包裹硫化物珠滴的橄榄石的Fo牌号通常低于85。这些特征指示母岩浆演化过程中夏日哈木岩体的S饱和与硫化物熔离阶段早于石头坑德。另一方面,夏日哈木和石头坑德岩体的全岩δ^(34) S值均明显高于地幔(-2‰~+2‰),暗示二者母岩浆演化�The world-class Xiarihamu Ni-Co sulfide deposit,along with several contemporary sulfide-bearing mafic-ultramafic intrusions(for example,the Shitoukengde intrusion),occur within the East Kunlun Orogen.Despite sharing similar mineralogical and petrological features,the Xiarihamu deposit and the Shitoukengde intrusion contain significantly different scales of sulfide mineralization.These features offer a unique opportunity to investigate the mechanism underlying sulfur saturation in mantle-derived magma and to discern the key factors controlling magmatic sulfide mineralization within an orogenic belt.In this study,we investigate the geochemical compositions of the olivine and the whole-rock sulfur(S)isotopic compositions from both the Xiarihamu and Shitoukengde to elucidate the formation of magmatic sulfide deposits in the East Kunlun orogenic belt.The forsterite(Fo)values of the olivine in the Xiarihamu range from 82.3 to 90.0,with Ni contents of 558×10^(-6)~4370×10^(-6).By contrast,the Fo values of olivine in the Shitoukengde intrusion vary from 79.9 to 90.2,with the Ni contents of 300×10^(-6)~3040×10^(-6).The whole-rockδ^(34) S values for the Xiarihamu intrusion vary from 4.0‰to 6.4‰,with an average value of 5.2‰,while those of the Shitoukengde intrusion range from 1.8‰to 4.6‰,averaging at 3.2‰.The Ni contents in olivine with elevated Fo values at Xiarihamu(up to 4000×10^(-6))significantly exceed those at Shitoukengde(typically below 3000×10^(-6)),indicating a higher Ni content in the parental magma of the former compared to the latter.The olivine in the dunite at Shitoukengde is characterized by high Fo values and low Ni abundances,showing a negative correlation between them.These observations imply that the parental magma of the Shitoukengde intrusion underwent contamination by Mg-rich carbonates during its magmatic differentiation.The incorporation of Mg-rich components not only facilitated the crystallization of olivine with elevated Fo values,but also prolonged its crystallization period.G

关 键 词：东昆仑造山带 镁铁-超镁铁质岩体 岩浆硫化物矿床 橄榄石 S同位素 

分 类 号：P578.942[天文地球—矿物学] P588.125[天文地球—地质学] P597.2P611.1