| 粤北长江花岗岩型铀矿田沥青铀矿原位U-Pb年代学研究及其地质意义 |
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| 引用本文： | 钟福军,严杰,夏菲,潘家永,刘文泉,赖静,赵奇峰.粤北长江花岗岩型铀矿田沥青铀矿原位U-Pb年代学研究及其地质意义[J].岩石学报,2019,35(9):2727-2744. |
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| 作者姓名： | 钟福军 严杰 夏菲 潘家永 刘文泉 赖静 赵奇峰 |
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| 作者单位： | 东华理工大学, 核资源与环境国家重点实验室, 南昌 330013,东华理工大学, 核资源与环境国家重点实验室, 南昌 330013,东华理工大学, 核资源与环境国家重点实验室, 南昌 330013;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 33001,东华理工大学, 核资源与环境国家重点实验室, 南昌 330013;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 33001,东华理工大学, 核资源与环境国家重点实验室, 南昌 330013;核工业290研究所, 韶关 512026,核工业290研究所, 韶关 512026,核工业270研究所, 南昌 330013 |
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| 基金项目： | 本文受国家重点研发计划项目（2017YFC0602600）、国家自然基金项目（41772066、41702076、41902075）、核资源与环境国家重点实验室开放基金项目（NRE1807）和江西省教育厅科技项目（GJJ180394）联合资助. |
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| 摘 要： | 花岗岩型铀矿床是我国重要的工业铀矿床类型,广泛分布于南岭地区。粤北长江铀矿田位于南岭中段诸广山岩体中南部,是我国典型的花岗岩型铀矿田。由于铀矿物在化学组成和成因上的固有属性,前人通过传统的铀矿物U-Pb同位素定年获得的成矿年龄(157～52Ma)变化范围较大且分散,难以有效约束精确的铀成矿时代。本文在精细矿物学研究的基础上,对长江铀矿田棉花坑、书楼坵和长排三个铀矿床的沥青铀矿开展了LA-ICP-MS原位微区U-Pb同位素定年研究。结果表明,棉花坑矿床成矿年龄为60. 8±0. 6Ma和66. 8±1. 6Ma,书楼坵矿床成矿年龄为71. 4±1. 3Ma和74. 4±1. 7Ma,长排矿床成矿年龄为62. 4±2. 5Ma和70. 2±0. 5Ma,总体分为～75Ma、～70Ma和～60Ma三期成矿年龄,代表了华南花岗岩型铀矿的晚期铀矿化。长江铀矿田成矿时代与诸广地区北东向断裂带、断陷盆地的强烈拉张时期(80～60Ma)同步,指示区内铀矿化与南岭地区晚白垩世-古近纪地壳拉张作用有关,区内铀成矿的幔源矿化剂CO_2来自区域性北东向断裂带的拉张作用。综合前人资料,认为诸广地区的铀成矿具同时性和多期性特征,成矿峰期为～140Ma、～125Ma、～105Ma、～90Ma和80～60Ma,成矿统一受制于华南岩石圈伸展的动力学背景,诸广山-南雄盆山体系白垩-古近纪的构造演化可能是促使区域铀矿化形成的主要因素。
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| 关 键 词： | 原位U-Pb定年 沥青铀矿 铀成矿作用 长江铀矿田 |
| 收稿时间： | 2019/2/11 0:00:00 |
| 修稿时间： | 2019/6/28 0:00:00 |
In-situ U-Pb isotope geochronology of uraninite for Changjiang granite-type uranium ore field in northern Guangdong, China: Implications for uranium mineralization |
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| ZHONG FuJun,YAN Jie,XIA Fei,PAN JiaYong,LIU WenQuan,LAI Jing and ZHAO QiFeng.In-situ U-Pb isotope geochronology of uraninite for Changjiang granite-type uranium ore field in northern Guangdong, China: Implications for uranium mineralization[J].Acta Petrologica Sinica,2019,35(9):2727-2744. |
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| Authors: | ZHONG FuJun YAN Jie XIA Fei PAN JiaYong LIU WenQuan LAI Jing and ZHAO QiFeng |
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| Institution: | East China University of Technology, State Key Laboratory of Nuclear Resources and Environment, Nanchang 330013, China,East China University of Technology, State Key Laboratory of Nuclear Resources and Environment, Nanchang 330013, China,East China University of Technology, State Key Laboratory of Nuclear Resources and Environment, Nanchang 330013, China;East China University of Technology, Fundamental Science on Radioactive Geology and Exploration Technology Laboratory, Nanchang 33001,East China University of Technology, State Key Laboratory of Nuclear Resources and Environment, Nanchang 330013, China;East China University of Technology, Fundamental Science on Radioactive Geology and Exploration Technology Laboratory, Nanchang 33001,East China University of Technology, State Key Laboratory of Nuclear Resources and Environment, Nanchang 330013, China;No. 290 Research Institute, China National Nuclear Corporation, Shaoguan 512026, China,No. 290 Research Institute, China National Nuclear Corporation, Shaoguan 512026, China and No. 270 Research Institute, China National Nuclear Corporation, Nanchang 330013, China |
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| Abstract: | Granite-type uranium deposit is an important industrial type of uranium deposit in China, which is widespread in the Nanling region. The Changjiang uranium ore field, which located at central-south of Zhuguangshan complex in Nanling region, is one of representative granite-type uranium ore fields of South China. Because of the nature of mineral chemical composition and origin of uranium minerals, the ore-forming ages (157~52Ma) obtained by conventional U-Pb isotopic dating in previous literature showed a wide range and failed to reveal the ore-forming ages for Changjiang uranium ore field. In this paper, we carry out detailed investigations upon updated mineralogy and in-situ U-Pb geochronology of uraninite. U-Pb ages of uraninite in six typical uranium ore samples stretch across a narrow number range (Mianhuakeng deposit of 60.8±0.6Ma and 66.8±1.6Ma, Shulouqiu deposit of 71.4±1.3Ma and 74.4±1.7Ma, Changpai deposit of 62.4±2.5Ma and 70.2±0.5Ma), suggesting the main uranium mineralization likely occurred at three stages of~75Ma,~70Ma and~60Ma. These new in-situ U-Pb ages of uraninite, which represent the late uranium mineralization of granite-type uranium deposit in South China, are synchronous with the extension period (80~60Ma) of NE-trending fault subsidence zones and fault basins in Zhuguang area, suggesting the uranium mineralization has closely genetic relationship with Late Cretaceous-Paleocene crust extension in Nanling region. The mantle-source mineralizer CO2 for uranium mineralization were possibly derived from the extension of regional NE-trending fault zones. Combined with previous data, the uranium mineralization in Zhuguang area is characterized by simultaneity and multiple stages (~140Ma,~125Ma,~105Ma,~90Ma and 80~60Ma), and occurred at the Cretaceous-Paleogene lithospheric extensional dynamic setting of South China. The Cretaceous-Paleogene tectonic evolution of basin-range, within the Zhuguangshan complex and Nanxiong basin, was possibly responsible for the genesis of uranium mineralization in Zhuguang area. |
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| Keywords: | In-situ U-Pb dating Uraninite Uranium mineralization Changjiang uranium ore field |
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