鄂尔多斯盆地西缘环县地区直罗组沉积相及其与铀矿化的关系

含矿层沉积相及沉积砂体是控制铀矿化的重要因素之一,综合利用钻井岩芯观察、岩石薄片分析、测井等资料,编制典型钻孔柱状图、地层厚度、砂岩厚度及砂岩百分含量图等,对环县地区直罗组沉积相及其对铀矿化的关系进行研究。结果表明:环县地区直罗组早期以辫状河沉积为主,发育辫状河道和泛滥平原等沉积微相;晚期为曲流河沉积,发育河道、河漫滩、天然堤等沉积微相。沉积相对该区铀成矿具有明显的控制作用:辫状河道为铀矿化富集最有利部位;砂体厚度及沉积微相控制着铀矿化的空间展布,主要分布在辫状河道的边部砂体减薄的地带及与泛滥平原相变地带。

Sedimentary Facies of the Zhiluo Formation and Its Relationship with Uranium Mineralization in the Huanxian Area, West of Ordos Basin

The sedimentary facies and sands are important factors that controlled the uranium mineralization.The sedimentary facies of the Zhiluo formation and the relationship with uranium mineralization in the Huanxian Area are studied based on drilling core observation,analysis of well logging, thin section and mapping of stratum thickness, sandstone thickness, percent-age of sandstone. The results indicate that the main sedimentary facies of lower Zhiluo formationa are braided river include distributary channel and flood plain,while that of the later Zhiluo formationa are mainly meandering river include distributary channel, alluvial flat and natural levee. The uranium mineralization is mainly controlled by sedimentary facies, braided channel creates the favourable setting for uranium deposition; the distribution of uranium sand caused by changes of sedimentary microfacies and sand thicker, enrichment of uranium are braided channel where the sand body is thinner, and facies change zones with fiood plain.