阳山金矿成矿流体的He-Ar同位素示踪  

He-Ar Isotopes Tracing for Ore Genesis of the Yangshan Gold Deposit

作　　者：丁德建 梁金龙[1] 孙卫东[2] 郭俊华[3] 李贺[2] 叶先仁[4] 

机构地区：[1]江西地矿局赣东北地质大队,江西上侥334000 [2]中国科学院广州地球化学研究所,矿物学与成矿学重点实验室,广州510640 [3]中国人民武装警察部队黄金第十二支队,成都610036 [4]中国科学院气体地球化学实验室,兰州730000

出　　处：《矿物岩石地球化学通报》2014年第6期813-819,共7页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金项目(41273031);中核集团铀矿事业部项目(201148)

摘　　要：甘肃阳山金矿的成因类型及成矿流体来源多年来颇受关注,本文利用惰性气体同位素质谱仪测定了该矿床黄铁矿和石英样品中流体包裹体He、Ar同位素组成.结果显示,成矿流体的3He/4 He值为0.03～0.08 Ra,指示成矿流体来源于壳源,不含幔源He;40 Ar/36 Ar值为434.1～863.0,稍高于大气饱和水（295.5）,流体中除地壳放射成因Ar外,还有大气Ar,表明大气降水曾参与成矿.结合矿床地质特征,认为阳山金矿成矿流体是以造山作用产生的变质水与经断裂下渗的大气饱和水为主,下渗的大气饱和水与高U、Th含量的花岗岩发生水-岩交换,导致了成矿流体中极低的40Ar＊/4He（0.0227～0.0539）.The Yangshan gold deposit attracted research interests for its ore genesis and ore-forming fluid sources.This study analyzed Helium and Argon isotopes compositions in fluid inclusions of the pyrite-quartz veins.The results showed that 3 He/4 He ratios of the Yangshan gold deposit are within 0.03-0.08 Ra,indicating that the oreforming fluids were crust-derived fluids with no mantle-derived He.The 40 Ar/36 Ar ratios varied from 434.1 to 863.0,which are higher than that of the air saturated water （295.5）,indicated that the air-saturated water was involved in the ore-forming process.Combined with geological characteristics of the deposit,we suggested that the ore-forming fluids of the Yangshan gold deposit were mainly the crust-derived metamorphic fluids mixed with airsaturated water.The air-saturated water seeped down along fault systems and extracted radiogenic 4 He and 40 Ar by water-rock exchanging with country rocks of high U and Th contents,and resulted in low 40Ar/4 He ratios （0.0227 -0.0539） in the ore-forming fluids.Conclusively,we suggested that the Yangshan gold ore deposit should be classified into the orogenic deposit.

关 键 词：阳山金矿 成矿流体 HE-AR同位素 

分 类 号：P618.51[天文地球—矿床学]