内蒙古东胜大型砂岩型铀矿床稀土元素地球化学研究

发布时间：2018-11-18 08:19

【摘要】：东胜砂岩型铀矿位于鄂尔多斯盆地北部,矿化受灰绿色砂岩控制,不同于典型层间氧化带成矿模式。在前人研究的基础上,本文系统的总结了该铀矿床的稀土元素地球化学特征,讨论了水-岩反应过程中稀土元素地球化学行为。对围岩、矿化砂岩及铀矿石的稀土元素组成、关系及成因研究发现REE与U呈正相关性,对铀矿化具有指示意义,各类岩石稀土配分曲线形态相似但又存在差异,说明它们沉积成岩环境相同,形成不同品位铀矿体的流体具有不同来源和演化过程。元素等位线研究表明,稀土元素在不同成矿过程表现出不同的活动性,总体可以划分两个过程,一是低品位铀矿石的形成过程,稀土元素活动性较弱;一是高品位铀矿石的形成过程,稀土元素活动性明显增强。结合Ce、Eu异常和REE活动性特征,认为区内铀矿化流体以具低温及偏碱性特点的地下水为主,REE主要以[REE(CO_3)_3]~(3-)的形式迁移,pH、Eh及温度压力的降低是导致U和REE沉淀的重要因素。
[Abstract]:Dongsheng sandstone-type uranium deposit is located in the northern part of Ordos Basin, and the mineralization is controlled by grey-green sandstone, which is different from the metallogenic model of typical interlayer oxidation zone. On the basis of previous studies, this paper systematically summarizes the geochemical characteristics of rare earth elements in the uranium deposit, and discusses the geochemical behavior of rare earth elements in the process of water-rock reaction. The study on the composition, relationship and genesis of rare earth elements in surrounding rock, mineralized sandstone and uranium ore shows that REE has positive correlation with U, which is instructive to uranium mineralization. The rare earth distribution curves of various rocks are similar in shape but different in shape. The results show that the sedimentary diagenetic environment is the same and the fluids forming different grade uranium ore bodies have different sources and evolution processes. The study of element alleles shows that rare earth elements exhibit different activity in different metallogenic processes, which can be divided into two processes: one is the formation process of low grade uranium ores, and the activity of rare earth elements is weak; One is the formation process of high grade uranium ores, and the activity of rare earth elements increases obviously. According to the characteristics of Ce,Eu anomaly and REE activity, it is considered that the uranium mineralized fluid in this area is mainly groundwater with low temperature and alkalinity, REE is mainly migrated in the form of [REE (CO_3) _ 3] ~ (3-), pH, The decrease of Eh and temperature and pressure are the important factors to precipitate U and REE.
【作者单位】：天津地质矿产研究所;
【基金】：国家重点基础计划项目(编号:2015CB45300) 中国地质调查局项目(编号:1212011307800)
【分类号】：P619.14

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