河北沽源张麻井铀钼矿床He-Ar同位素示踪  

He-Ar Isotope Tracing of Zhangmajing Uranium-Molybdenum Deposit in Guyuan, Hebei

作　　者：朱斌 黄志新[1] 李子颖[1] 孙小聪 ZHU Bin;HUANG Zhixin;LI Ziying;SUN Xiaocong(Beijing Research Institute of Uranium Geology,CNNC Key Laboratory of Uranium Resource Exploration and Evaluation Technology,Beijing 100029,China)

机构地区：[1]核工业北京地质研究院中核集团铀资源勘查与评价技术重点实验室

出　　处：《铀矿地质》2019年第5期257-264,共8页Uranium Geology

摘　　要：张麻井矿床是产于华北陆块北缘早白垩世流纹斑岩体内的一个大型火山岩型铀钼矿床。为查明该矿床的成矿流体来源,对成矿流体的He-Ar同位素进行了测定。分析结果表明,石英和萤石中流体包裹体的^3He/^4He分别为0.64Ra^6.73Ra和0.02Ra^0.39Ra;^40Ar/^36Ar分别为296.4~362.1和265.7~330.8。成矿流体具有幔源流体和壳源流体混合的特点,且幔源流体具有接近岛弧深部地幔流体的He、Ar同位素组成特征。结合矿床地质和地球化学特征,认为幔源流体的来源与喜山期裂陷玄武岩活动有关。Zhangmajing deposit is a large scale volcanic uranium-molybdenum deposit located in the northern margin of the North China Craton,its orebodies are mainly developed in the Lower Cretaceous rhyolite porphyry.In order to trace the source of ore-forming materials,He-Ar isotopes of ore-forming fluids were determined.The results showed that 3He/4He ratios of fluid inclusions in quartz and fluorite vary from 0.64 to 6.73Ra and 0.02 to 0.39Ra,respectively,and 40Ar/36Ar ratios vary from 296.4 to 362.1 and 265.7 to 330.8,respectively.The ore-forming fluids are characterized by the mixing of mantle-derived fluids and crust-derived fluids,and the mantle-derived fluids bear He and Ar isotopic compositions close to those of fluids generated from the mantle beneath the island arc.Based on the above study and combining with the geological and geochemical characteristics of the deposit,we proposed that the source of mantle-derived fluids is mainly related to the interruption of basalt during the Himalayan period.

关 键 词：HE-AR同位素 成矿流体 地幔流体 张麻井矿床 火山岩型铀钼矿 

分 类 号：P619.14[天文地球—矿床学]