松辽盆地东北部拜泉地区姚家组砂岩特征及铀成矿地球化学环境分析  

Sandstone Characteristics and Geochemical Environment Analysis With Uranium Mineralization of Yaojia Formation in Baiquan Area,Northeastern Songliao Basin

作　　者：罗敏 刘晓辉 吴大坤 王东旭 LUO Min;LIU Xiaohui;WU Dakun;WANG Dongxu(Research Institute No.240,CNNC,Shenyang,Liaoning 110000,China)

机构地区：[1]核工业二四〇研究所,辽宁沈阳110000

出　　处：《铀矿地质》2023年第3期323-336,共14页Uranium Geology

基　　金：中国核工业地质局项目“松辽盆地北部泰来-拜泉地区铀矿资源调查评价”(编号:202024)资助。

摘　　要：松辽盆地东北部拜泉地区姚家组主要表现为河流相沉积特征,砂岩厚度大且延伸稳定,颜色分为黄色、黄绿色、白色、浅灰色和灰色,目前已在浅灰色砂岩中发现铀矿化,但是对该区是否存在氧化带及其铀矿化成因认识尚不明确。文章通过对不同颜色砂岩地球化学环境指标元素、微量元素、稀土元素和黏土矿物的研究,判断其地球化学环境,推测氧化带前锋线位置及判断铀富集的有利部位,有助于进一步明确该区找矿思路和方向。文章采集了拜泉地区8个钻孔的93个不同颜色砂岩样品的U、Th、Fe^(3+)、Fe^(2+)、S_(全)、C_(有)等元素分析结果进行统计研究,并在其中选取25件不同颜色的砂岩样品进行X-射线衍射分析。结果显示:(1)所有颜色砂岩中,白色砂岩的w(U)值最低,w(Th)、Th/U值最高,w(U)、w(Th)值在不同颜色砂岩之间具有分带性;(2)所有颜色砂岩的w(Fe^(3+)+Fe^(2+))值都偏低,其变化具有分带性,其中黄色砂岩Fe^(3+)/Fe^(2+)值最高,w(C_(有))值在不同颜色砂岩之间具有分带性,w(S_(全))值在不同颜色砂岩之间分带性不明显;(3)所有颜色砂岩黏土矿物均以蒙脱石、高岭石和绿泥石为主,伊利石和混合层黏土含量较少,黄色—黄绿色—白色—浅灰色—灰色砂岩的蒙脱石含量逐渐升高,绿泥石含量逐渐降低。白色砂岩的黏土矿物总量明显高于其他颜色的砂岩,其中高岭石、伊利石含量相对较高,蒙脱石、绿泥石含量相对较低;(4)不同颜色砂岩的w(Na_(2)O)和w(K_(2)O)值变化存在黄色—黄绿色—白色—浅灰色—灰色砂岩逐渐升高的趋势;(5)灰色砂岩稀土元素配分曲线相对集中,而黄色、黄绿色、白色和浅灰色砂岩稀土元素分布比较分散,计算Ce_(anom)值显示,姚家组的砂岩形成于缺氧、还原的古水体环境。通过上述研究结果认为拜泉地区姚家组砂岩形成于还原环境,黄色、黄绿色、白色砂岩受到后生Yaojia Formation in Baiquan area,northeast of Songliao Basin,is mainly characterized by fluvial facies sedimentation.The sandstone is thick and extends stably.Color of the sandstone can be divided into yellow,yellow green,white,light gray and gray.Uranium mineralization was found in light gray sandstone,but it is not clear whether there is an oxygenation zone in this area and what is the origin of uranium mineralization.Through the study of geochemical environmental indicator elements,trace elements,rare earth elements and clay minerals of sandstone of different colors,this paper fount their geochemical environment and inferred the front line of the oxidation zone and predicted the favorable position of uranium enrichment.The paper collected 93 sandstone samples of different colors from 8 boreholes in Baiquan area for the element analysis of U,Th,Fe^(3+),Fe^(2+),S total and C has,and selected 25 sandstone samples of different colors for X-ray diffraction analysis.The results showed that:①The white sandstone had the lowest w(U)value,the highest w(Th)and Th/U values,and the w(U)and w(Th)values were zoned among the sandstones of different colors;②The w(Fe^(3+)+Fe^(2+))values of sandstones of all colors were low,and their changes were zonal.Among them,the yellow sandstone had the highest Fe^(3+)/Fe^(2+)U value,the w(C_(has))value was zonal between sandstones of different colors,and the w(S_(total))value was not obvious between sandstones of different colors;③The clay minerals of sandstone in all colors were mainly montmorillonite,kaolinite and chlorite.The content of illite and mixed layer clay was less.The content of montmorillonite in yellow yellow green white light gray gray sandstone gradually increases,while the content of chlorite gradually decreases.The total amount of clay minerals of white sandstone was obviously higher than that of sandstone of other colors,in which the content of kaolinite and illite was relatively high,and the content of montmorillonite and chlorite is relatively low;④The variatio

关 键 词：地球化学环境 姚家组 砂岩型铀矿 拜泉地区 松辽盆地东北部 

分 类 号：P619.14[天文地球—矿床学]