粤北湖子对山铀矿床年代学与矿物化学研究及其对铀成矿的启示  

Geochronology and mineral chemistry study on Huziduishan uranium deposit in northern Guangdong Province and its implications for uranium mineralization

作　　者：肖为[1] 范洪海 庞雅庆[1] 陈东欢[1] 赖中信 XIAO Wei;FAN HongHai;PANG YaQing;CHEN DongHuan;LAI ZhongXin(CNNC Beijing Research Institute of Uranium Geology,Beijing 100049,China;No.293 Geologic Party Guangdong Nuclear Industry Buerau,Guangdong 510800,Guangzhou,China)

机构地区：[1]核工业北京地质研究院,北京100049 [2]广东省核工业地质局293大队,广东广州510800

出　　处：《矿床地质》2022年第2期383-402,共20页Mineral Deposits

基　　金：中国核工业地质局《华南富大铀矿空间定位条件与远景预测研究》(编号:202138-10)资助。

摘　　要：湖子对山铀矿床位于粤北下庄铀矿田的中部,研究程度较低,对该矿床成矿时代和矿床成因缺乏必要的约束。文章通过LA-ICP-MS等技术手段,对湖子对山铀矿床开展了沥青铀矿U-Pb年代学及微量元素分析,结合矿石中黄铁矿LA-ICP-MS微量元素及硫同位素分析结果,对该矿床的成矿时代、成矿物质来源及矿床成因展开了讨论。研究表明,沥青铀矿中具有较高的普通铅含量,Tera-Wasserburg图解的投图结果表明其形成于(61.6±3.9)Ma(MSWD=1.4),与区域上部分铀矿床成矿时代一致,代表了华南地区一期重要的区域铀成矿事件。沥青铀矿中普通铅的^(207)Pb/^(206)Pb为0.624,表明成矿物质来源于积累了部分放射性成因铅的富铀源区,普通Pb可能以超显微非结构混入物的形式分布于沥青铀矿中。沥青铀矿LA-ICP-MS微量元素组成与黄铁矿显著不同,以富集W、Bi、Pb、Mo、Sb和亏损Cr、Co、Ni、Ti、As等元素为特征,表明成矿物质可能主要来源于花岗岩。黄铁矿微量元素具有低Co、Ni和富As的特征,表明其中低温热液成因,其Bi和Pb、Sb等元素含量较低,与沥青铀矿显著不同,结合镜下观察结果,认为黄铁矿形成于成矿前。该矿床黄铁矿硫同位素结果与诸广-下庄地区部分铀矿床结果一致,且接近于区域花岗岩硫同位素值,而区别于辉绿岩,表明该区部分铀矿床黄铁矿中的硫主要来源于区域花岗岩。The Huziduishan uranium deposit is located in the middle of the Xiazhuang uranium ore field in northern Guangdong,which has a low degree of research and lacks necessary constraints on the metallogenic age and gene-sis of the deposit.In this paper,U-Pb chronology and trace element analysis of pitchblende from the Huziduishan uranium deposit have been carried out by means of LA-ICP-MS and other technical methods.Combined with the results of LA-ICP-MS trace element and sulfur isotope analysis of pyrite in the ore,the ore-forming age,material source and the genesis of the deposit are discussed.The study shows that pitchblende has a high content of com-mon lead,and the results of Tera-Wasserburg diagrams yield an age of(61.6±3.9)Ma(MSWD=1.4),which is con-sistent with the uranium metallogenic age of some uranium deposits in the region,and represents an important re-gional uranium metallogenic event in South China.The^(207)Pb/^(206)Pb of common lead in pitchblende is 0.624,indi-cating that the ore-forming materials are derived from uranium-rich sources that have accumulated part of radio-genic lead,and the common Pb may be distributed in pitchblende as ultramicroscopic unstructured mixtures.The trace element composition of pitchblende from LA-ICP-MS analysis is significantly different from that of pyrite,which is characterized by enrichment of W,Bi,Pb,Mo,Sb and depletion of Cr,Co,Ni,Ti and other elements,in-dicating that the ore-forming materials may be mainly derived from granites.The trace elements of pyrite have the characteristics of low Co,Ni and rich As,indicating its low temperature hydrothermal genesis and low con-tents of Bi,Pb,Sb and other elements,which are significantly different from pitchblende.Combined with the re-sults of microscopic observation,it is considered that pyrite was formed before U mineralization.The sulfur iso-tope values of pyrite in this deposit are consistent with those of some uranium deposits in the Zhuguang and Xia-zhuang uranium ore field,and are close to the sulfur isotope values of

关 键 词：地球化学 U-PB定年 沥青铀矿 黄铁矿 LA-ICP-MS 湖子对山 

分 类 号：P619.14[天文地球—矿床学]