赣南会昌辉石闪长岩中磷灰石和锆石的年代学、成因矿物学及铀成矿指示意义  

Geochronology and Genetic Mineralogy of Apatite and Zircon from the Huichang Pyroxene Diorite in Southern Jiangxi Province:Implications for Uranium Mineralization

作　　者：曾认宇 潘家永[1,2] 苏惠 甘德斌 钟福军 杜后发[1,2] 严杰 张辰光 Zeng Renyu;Pan Jiayong;Su Hui;Gan Debin;Zhong Fujun;Du Houfa;Yan Jie;Zhang Chenguang(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;School of Earth Sciences,East China University of Technology,Nanchang 330013,China;Department of Earth Sciences,Durham University,Durham DH13LE,UK;School of Geographic Sciences,Xinyang Normal University,Xinyang 464000,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,江西南昌330013 [2]东华理工大学地球科学学院,江西南昌330013 [3]英国杜伦大学地球科学学系,杜伦DH13LE [4]信阳师范学院地理科学学院,河南信阳464000

出　　处：《地球科学》2023年第9期3258-3279,共22页Earth Science

基　　金：国家自然科学基金项目(Nos.41902075,42030809,42002095,42162013);江西省自然科学基金资助项目(No.20232BAB213061);核资源与环境国家重点实验室开放基金项目(No.2020NRE13);国家留学基金委访问学者项目(No.202008360018).

摘　　要：华南中生代幔源岩浆的时空分布与铀成矿具有密切的联系.然而,解释幔源岩浆中锆石的成因和来源,厘清幔源岩浆的侵位年龄,一直是相关研究的重点和难点.以赣南会昌地区出露的一处幔源辉石闪长岩为研究对象,对其开展了锆石和磷灰石的矿相学、矿物地球化学和年代学系统研究.会昌辉石闪长岩的SiO_(2)在55.74%~57.71%之间,富集LREE和LILE,亏损HREE和HFSE.磷灰石属于氟磷灰石,显示了115.0±4.9 Ma的交点年龄和114.7±2.3 Ma的加权平均年龄,代表了会昌辉石闪长岩的侵位年龄;锆石的^(206)Pb/^(238)U年龄介于233~271 Ma,ε_(Hf)(t)在-3.0~-1.4之间,为来源于深部I型花岗岩的捕获锆石.结合前人在区域上的研究,华南板块在印支期主要处于挤压环境,形成了大量的S型和I型花岗岩;到了白垩纪,华南板块整体处于伸展环境,存在多期次的幔源岩浆活动.而在这种伸展环境中,天水和幔源流体带来了充足的O_(2)和CO_(2)等矿化剂,这为浸取矿源层中的U元素,进而形成铀矿提供了重要的条件.The spatial and temporal distribution of Mesozoic mantle-derived magma in South China is closely related with the metallogenic model of the granite-type uranium deposit.However,it has always been an important yet difficult issue of studies to explain the origin of zircon in mantle-derived magma and clarify the emplacement age of mantle-derived magma.Focusing on a newly discovered mantle-derived pyroxene diorite in the Huichang area,southern Jiangxi Province,this paper presents a systematic study on its mineralogy,mineral geochemistry,chronology and bulk geochemistry.The Huichang pyroxene diorite is characterized by SiO_(2)contents of 55.74%-57.71%,and enrichment in LREE and LILE,and depletion in HREE and HFSE.Apatite belongs to fluoroapatite,and the intercept age(115±4.9 Ma)and weighted mean^(206)Pb/^(238)U age(114.7±2.3 Ma)of apatite represent the crystallization age of Huichang pyroxene diorite.While,the zircons have^(206)Pb/^(238)U age of 233-271 Ma andε_(Hf)(t)value of-3.0 to-1.4,which indicate the captured zircon from I-type granite.Combined with the previous regional geological data,the South China block was mainly in a compression environment in the Indosinian,forming a large number of S-type and I-type granites.In the Cretaceous,the South China block was mainly in an extensional environment,and multiple stages of mantle-derived magmas underplating events occurred.In the extensional environment,meteoric water and mantle-derived fluids brought sufficient mineralizers such as O_(2)and CO_(2),which provided important conditions for leaching uranium from source bed and finally forming the uranium deposits.

关 键 词：U⁃Pb定年 磷灰石 锆石 辉石闪长岩 赣南 铀成矿 岩石学 矿物学 

分 类 号：P597[天文地球—地球化学] P611[天文地球—地质学]