赣中潭港盆地早白垩世火山岩地质特征及其铀成矿潜力分析  

Geological Characteristics and Uranium Metallogenic Potential of the Early Cretaceous Volcanic Rocks in the Tangang Area of the Central Jiangxi

作　　者：夏寅初 张树明[1,2] 张鑫[1,2] 刘龙[1] 万康 欧阳军勇 吴志春[1,2] XIA Yin-chu;ZHANG Shu-ming;ZHANG Xin;LIU Long;WAN Kang;OUYANG Jun-yong;WU Zhi-chun(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;Fundamental Science on Radioactive Geology and Exploration Technology Laboratory,East China University of Technology,Nanchang 330013,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,南昌330013 [2]东华理工大学放射性地质与勘探技术国防重点学科实验室,南昌330013

出　　处：《矿物岩石地球化学通报》2022年第2期429-444,共16页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目(41862006,41802247)。

摘　　要：相山火山盆地产出有我国最大的火山岩型铀矿床,与之毗邻的潭港火山盆地中火山岩大量发育,为探究这些火山岩的铀成矿潜力,对其进行了岩相学、元素地球化学、锆石U-Pb年代学和Sr-Nd-Pb同位素分析。结果表明,潭港火山岩的形成时间为136.78~137.62 Ma;具有富硅(SiO_(2)含量为66.80%~72.25%)、富碱(Na_(2)O+K_(2)O含量为7.65%~8.00%)、富钾(K_(2)O/Na_(2)O含量为1.68~2.34),富轻稀土元素和Rb、Th、Nd、Zr、Hf,亏损Ba、Ta、Nb、Sr,以及中等负铕异常(δEu为0.41~0.47),较高的I_(Sr)(0.71107~0.71139),较低的ε_(Nd)(t)值(-8.16~-7.6),较高的Δβ值(19.28~20.06),较高的Δγ值(42.66~44.37)等特征。研究表明,潭港火山岩与相山铀矿田主要含矿主岩——碎斑熔岩的地质特征基本相同,形成时代均为早白垩世早期,是区域同一期岩浆活动的产物,其形成环境均为陆内伸展拉张环境,成岩物质主要来源于上地壳,且类似的热液蚀变较发育,具有与相山铀矿田类似的铀成矿地质条件,具有铀成矿潜力。A large amount of volcanic rocks are distributed in the Tangang volcanic Basin.The adjacent Xiangshan volcanic basin has the largest volcanic rock type uranium deposit in China.In order to explore the uranium metallogenic potential of volcanic rocks in the Tanggang Basin,the volcanic rocks have been selected as research objects for undertaking systematical studies of the petrographic observation,elemental geochemistry,zircon U-Pb chronology,and Sr-Nd-Pb isotopes in this paper.The results show that diagenetic times of the Tangang volcanic rocks vary from 136.78 to 137.62 Ma.Geochemically,the Tangang volcanic rocks are characterized with high silicon(SiO_(2)=66.80%-72.25%),high alkali(Na_(2)O+K_(2)O=7.65%-8.00%),and high potassium(K_(2)O/Na_(2)O=1.68-2.34),with enriched LREE,Rb,Th,Nd,Zr,and Hf,depleted Ba,Ta,Nb,and Sr,moderately negative Eu anomaly(δEu=0.41-0.47),,relatively high I_(Sr) values(0.71107-0.71139),relatively lowε_(Nd)(t)values(-8.16--7.6),relatively highΔβvalues(19.28-20.06),and relatively highΔγvalues(42.66-44.37).The study shows that the Tangang volcanic rocks have basic common geological characteristics with the main ore-bearing rock,clastoporphyritic lava,in the Xiangshan uranium ore field.They were all formed in the early stage of the Early Cretaceous under the intracontinental extensional environment,as products of same period magmatic activity in this region.Their diagenetic materials were mainly derived from the upper crust.With similar hydrothermal alterations,the Tangang volcanic basin and the Xiangshan uranium ore field have similar uranium metallogenic geological conditions.Therefore,there is a good potential for uranium ore-forming in the Tangang Basin.

关 键 词：碎斑熔岩 地球化学特征 铀成矿潜力 潭港火山盆地 

分 类 号：P595[天文地球—地球化学]