青海东昆仑阿斯哈金矿床成矿物质来源:C-H-O-S-Pb同位素约束  

The origin of ore-forming material in the Asiha gold deposit,East Kunlun Orogenic Belt,Qinghai Province:Constraints from C-H-O-S-Pb isotopes

作　　者：岳维好 周家喜 高建国[5] 贾福聚[5] YUE Weihao;ZHOU Jiaxi;GAO Jianguo;JIA Fuju(College of Information Engineering,Kunming University,Kunming 650214,Yunnan,China;Key Laboratory of Data Governance and Intelligent Decision in Universities of Yunnan Province,Kunming 650214,Yunnan,China;School of Earth Sciences,Yunnan University,Kunming 650500,Yunnan,China;Key Laboratory of Critical Minerals Metallogeny in Universities of Yunnan Province,Kunming 650500,Yunnan,China;College of Land Resource Engineering,Kunming University of Science and Technology,Kunming 650093,Yunnan,China)

机构地区：[1]昆明学院信息工程学院,云南昆明650214 [2]云南省高校数据治理与智能决策重点实验室,云南昆明650214 [3]云南大学地球科学学院,云南昆明650500 [4]云南省高校关键矿产成矿学重点实验室,云南昆明650500 [5]昆明理工大学国土资源工程学院,云南昆明650093

出　　处：《地球化学》2023年第4期517-530,共14页Geochimica

基　　金：云南省地方本科高校基础研究联合专项(202101BA070001-077);昆明学院引进人才科研启动项目(YJL2003)联合资助。

摘　　要：都兰县阿斯哈金矿床位于青海东昆仑造山带东段,为近年来发现的大型金矿床。金矿体受NNE向和NNW-NW向断裂构造控制,赋存于闪长岩和花岗闪长岩体中。围岩蚀变强烈,主要有硅化、绢云母化、黄铁矿化、绿泥石化、碳酸岩化(方解石化)、绢云岩化、黄铜矿化和高岭土化。本文通过脉石矿物C-H-O同位素和矿石矿物S-Pb同位素地球化学研究,探讨该矿床成矿流体和成矿物质来源。方解石δ^(13)C值为−2.72‰~−2.46‰,δ^(18)O值为10.36‰~11.61‰,表明成矿流体主要来源于岩浆。石英δD值为−84.3‰~−59.6‰,δ^(18)O_(H_(2)O)值为5.7‰~12.0‰,进一步表明成矿流体属于岩浆流体。硫化物δ^(34)S值变化范围较窄,为3.2‰~7.7‰,平均值为6.1‰,与变质流体和沉积岩中的S同位素组成不同,而与中酸性岩浆S同位素组成相似,暗示S来源于中酸性岩浆。硫化物Pb同位素值变化较小(^(206)Pb/^(204)Pb=18.199~18.235,^(207)Pb/^(204)Pb=15.542~15.605,^(208)Pb/^(204)Pb=38.163~38.321),且落入造山带Pb演化线附近,指示造山作用对阿斯哈金矿床的形成可能有一定影响。结合已报道的成果,认为阿斯哈金矿床的成矿流体属于岩浆热液,成矿物质主要由中酸性岩浆提供,属于造山过程中形成的、与岩浆(很可能是已发现的斑岩)作用有关的热液脉型金矿床,为中–晚三叠世东昆仑造山伸展构造背景下岩浆–流体–构造耦合成矿的产物。The Asiha gold deposit in Dulan County is located in the eastern part of the East Kunlun orogenic belt in Qinghai Province.It is a large gold deposit discovered in recent years.The gold orebodies are controlled by NNE and NNW-NW trending faults and occur in diorite and granodiorite.Wallrock alteration is strong,mainly including silicification,sericitization,pyritization,chloritization,carbonatization(calcitization),sericite,brass mineralization,and kaolinization.Based on the geochemical study of C-H-O isotopes of gangue minerals and S-Pb isotopes of ore minerals,this paper discusses the source of ore-forming fluid and ore-forming material of the deposit.Calciteδ^(13)C values are−2.72‰to−2.46‰;theδ^(18)O values range from 10.36‰to 11.61‰,indicating that the ore-forming fluid mainly comes from magma.QuartzδD values are−84.3‰to−59.6‰;the values ofδ^(18)OH_(2)O vary from 5.7‰to 12‰,which further indicates that the ore-forming fluids were mainly derived from magma.Theδ34S values of sulfide range from 3.2‰to 7.7‰,with an average value of 6.1‰.It differs from the sulfur isotopic compositions of metamorphic fluid and sedimentary rocks,but similar to those of medium acid magma,suggesting that the source of sulfur is medium acid magma.The Pb isotope ratios of pyrite change slightly(^(206)Pb/^(204)Pb:18.199 to 18.235,^(207)Pb/^(204)Pb:15.542 to 15.605,^(208)Pb/^(204)Pb:38.163 to 38.321),and fall near the lead evolution line of the orogenic belt,suggesting that orogeny may have a certain impact on the formation of the Asiha gold deposit.Combined with the reported results,the authors believe that the ore-forming fluids of the Asiha gold deposit are magma hydrothermal fluid,and the ore-forming materials were mainly provided by medium acid magma.It belongs to hydrothermal vein-type gold deposit that formed in the process of orogeny and is related to magmatism(most likely discovered porphyry).It is the coupling mineralization result of magmatic-fluid-structure under the background of East Kunlu

关 键 词：C-H-O-S-Pb同位素 成矿流体 成矿物质来源 阿斯哈金矿床 东昆仑 青海 

分 类 号：P597[天文地球—地球化学] P618.51[天文地球—地质学]