摘要
摘要:对鄂尔多斯盆地北部铀成矿带产铀层位中侏罗统直罗组砂岩进行系统采样和分析，以探讨砂岩中粘土矿物特征与氧化带成因之间的关系。采用X‐射线粉晶衍射、电子探针分析等现代分析手段，测定粘土矿物相对含量、微观形貌特征。结果表明：研究区古层间氧化的演变序列为砂体原始灰色→古氧化作用（红色或黄色）→碳酸盐化（残留了部分红色）→后期还原作用（绿色），对应的岩石蚀变期次为早期氧化酸性蚀变→氧化期后弱碱性蚀变→晚期还原弱碱性蚀变；早期氧化砂岩在还原性气体作用下，Fe³⁺还原转化为Fe²⁺，高岭石在有Fe²⁺存在的条件下会向绿泥石转化，这一反应在碎屑颗粒表面，形成许多极细小的针叶状绿泥石，从而使古层间氧化亚带呈现特征的绿色。
关键词: 鄂尔多斯盆地/
砂岩型铀矿床/
粘土矿物/
古层间氧化带

Abstract:Systematic sampling and analysis of sandstones of Zhiluo Formation, Middle Jurassic in the uranium-producing horizon of the northern Ordos Basin are carried out to explore the relationship between the characteristics of clay minerals in sandstones and the genesis of the oxidation zone. The relative content and micro-morphological characteristics of clay minerals were determined by means of modern analysis methods such as X-ray powder diffraction, electron probe analysis. The results show that the evolution sequence of paleo-interlayer oxidation in the study area undergoes original gray of sand body→paleo-oxidation (red or yellow)→carbonation (residual red)→late reduction (green). The corresponding rock alteration stages are early oxidation acidic alteration→weak alkaline alteration after oxidation stage→late reduction weak alkaline alteration. Early oxidized sandstones are reduced to Fe²⁺ by reducing gas, and Kaolinite transforms to chlorite in the presence of Fe²⁺. On the surface of debris particles, a lot of very fine coniferous chlorite is formed, which makes the interlayer oxidation zone green.
Key words:Ordos Basin/
Sandstone uranium deposit/
Clay minerals/
Paleo-interlayer oxidation



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