诸广山中段“三九”地区铀矿放射性同位素特征及找矿潜力  

Radioisotopic Characteristics and Prospecting Potential of the Sanjiu Area in the Middle Zhuguangshan

作　　者：南小龙 施安荣 何友宇 谭延亮 姜必广[1,2] 陈旭 覃金宁 袁红志 蔡富成 何春明 王卡 NAN Xiaolong;SHI Anrong;HE Youyu;TAN Yanliang;JIANG Biguang;CHEN Xu;QIN Jinning;YUAN Hongzhi;CAI Fucheng;HE Chunming;WANG Ka(Hunan Institute of Geological and Geographic Information(Hunan Geological Big Data Center),Changsha,Hunan 410000;Hunan Engineering Research Center for Uranium Exploration Technology,Hengyang,Hunan 421008;Inner Mongolia Land Resources Exploration and Development Co.,Ltd,Hohhot,Inner Mongolia 010010;Hengyang NormalUniversity,Hengyang,Hunan 421006)

机构地区：[1]湖南省地质地理信息所(湖南省地质大数据中心),湖南长沙410000 [2]铀矿勘查技术湖南省工程研究中心,湖南衡阳421008 [3]内蒙古国土资源勘查开发有限公司,内蒙古呼和浩特010010 [4]衡阳师范学院,湖南衡阳421006

出　　处：《地质与勘探》2023年第2期248-258,共11页Geology and Exploration

基　　金：湖南省核工业地质局地勘项目(编号:DK306-20170512);衡阳师范学院铀矿勘查技术湖南省工程研究中心开放基金项目“湖南“三九”矿田九龙江铀矿床放射性同位素特征及找矿潜力分析”(编号:YK20K01)联合资助。

摘　　要：“三九”地区位于诸广山复式岩体中段,隶属华南花岗岩型铀矿富集区。放射性同位素及其比值是反映铀成矿信息的重要参数,可直接反映浅部到深部的铀、镭富集的地球化学特征及其迁移规律。本文重点探讨“三九”地区不同地段、不同含量、不同埋深和不同矿体部位的^(238)U、^(234)U、^(226)Ra、^(230)Th和^(231)Pa同位素特征及其比值,分析铀、镭迁移富集规律。结果表明:“三九”地区铀矿体由近地表至深部铀镭平衡系数具有高-低-高变化特征;U元素的相对富集、Th元素相对减低及其U/Th比值的急剧升高等特征,与U、Th丰度区间具有明显分带特征关系密切;当地表有矿化或异常显示且浅、深部有工业矿时,其同位素组成具有铀、镭同时迁出,且铀大量迁出特征;当地表无异常显示时,其同位素组成具有铀大量迁出、镭明显迁入特征。大于1的^(234)U/^(238)U比值可有效指示找铀矿化。综上,利用放射性同位素及其比值法在“三九”地区预测深部铀成矿有利地段,取得较好应用效果,其中九龙江、石壁窝和木洞三个地段的深部异常已被钻探工程揭露证实。本次研究对“三九”地区下一步铀矿找矿工作的部署与开展具有重要借鉴意义。The Sanjiu area is located in the central Zhuguangshan complex massif,which is part of South China granite-related uranium(U)enrichment area.Radioisotopes and their ratios are critical factors for determining U mineralization because they may directly represent the geochemical features and migration of U and radium(Ra)enrichment from shallow to deep.This work focused on the isotope characteristics and ratios of^(238)U,^(234)U,^(226)Ra,^(230)Th,and^(231)Pa with different area,contents,burial depths,and ore body parts,as well as the migration and enrichment of the U-Ra.The results demonstrate that the near surface to deep uranium ores in Sanjiu have a uranium-radium equilibrium coefficient with high-low-high fluctuation features.The quick rise in uranium relative enrichment,thorium relative reduction,and U/Th ratio corresponds to clear zonal patterns of U-Th abundance.When there are mineralization or anomalies on the local surface and there are industrial deposits in the shallow and deep parts,the isotopic composition has the characteristics of simultaneous migration of uranium and radium,and large migration of uranium.When there is no anomaly on the local surface,its isotope composition is characterized by a large amount of uranium migration and obvious radium migration.A^(234)U/^(238)U ratio larger than 1 can suggest U mineralization.Favorable areas for deep uranium mineralization were predicted in the Sanjiu area by using radioisotopic ratios.Further drilling confirms the anomalies of Jiulongjiang,Shiwo,and Mudong at deep.This research is critical for the deployment and implementation of the future exploration in the Sanjiu area.

关 键 词：放射性同位素 同位素比值 铀镭平衡 铀钍比 铀矿 三九地区 诸广山中段 

分 类 号：P593[天文地球—地球化学] P598[天文地球—地质学]