Abstract The Erlian basin is a very important uranium-bearing basin in China; that is located in the famous Central Asian Mobile Belt. It contains several concealed sandstone-type uranium deposits in sandstone and mudstone of Mesozoic-Cenozoic strata. Sampling of soil profiles over the Nuheting concealed U deposit in this basin shows that fine-grained soil collected from the horizon at depth of 15–30 cm has an obvious geochemical anomaly relative to background areas. Regional geochemical survey using fine-grained soil at a density of approximately 1 site per 4 km2 and groundwater at a density of approximately 1 site per 16 km2 or greater was carried out in the Erlian basin in an area of approximately 6400 km2. The survey results indicate that geochemical anomalies of U in the soil have a corresponding relationship with uranium-bearing geological bodies, including concealed uranium ore mineralization and granitic intrusions. Furthermore, groundwater chemistry determined from samples collected from wells is an effective supplementary means for exploration of concealed sandstone-type U deposits. The soil and groundwater geochemical anomalies may reduce the drilling density required to explore regionally, making them two effective and potentially cost-saving alternatives to regional geochemical exploration for concealed sandstone-type uranium deposits in basins. The formation of large-scale regional U anomalies in soil is a complicated process. A uranium vertical migration model for sandstone-type uranium was built for this study, where the water plays an important role in carrying soluble U in the form of uranyl through transport channels from mineralized bodies to Earth's surface under the action of groundwater motion and evapotranspiration. The study of the methods and anomaly formation mechanism is necessary for sandstone-type uranium exploration and will greatly enhance U resource exploration in covered arid terrains worldwide.

中文翻译：

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利用细粒土壤和地下水对东北二连盆地隐伏砂岩型铀矿进行区域地球化学调查

摘要 二连盆地是我国重要的含铀盆地；位于著名的中亚移动带。中、新生代地层砂岩、泥岩中含有多处隐伏砂岩型铀矿床。对该盆地怒河亭隐伏U矿床的土壤剖面取样表明，从地平层采集的15-30 cm深度的细粒土壤相对于背景区域具有明显的地球化学异常。在二连盆地约6400平方公里的范围内进行了密度约为每4平方公里1个点的细粒土壤和密度约为每16平方公里或更高点的地下水的区域地球化学调查。调查结果表明，土壤中U的地球化学异常与隐伏铀矿化和花岗岩侵入体等含铀地质体存在对应关系。此外，从井中采集的样品确定地下水化学是勘探隐伏砂岩型 U 矿床的有效补充手段。土壤和地下水地球化学异常可能会降低区域勘探所需的钻井密度，使其成为盆地隐伏砂岩型铀矿床区域地球化学勘探的两种有效且可能节省成本的替代方案。土壤中大尺度区域U异常的形成是一个复杂的过程。本研究建立了砂岩型铀的铀垂直迁移模型，其中，在地下水运动和蒸发蒸腾作用下，水通过从矿化体到地球表面的运输通道，在以铀酰形式携带可溶性 U 方面发挥着重要作用。对砂岩型铀矿勘探方法和异常形成机制的研究，将极大地促进全球覆盖干旱地区铀资源的勘探。