Keywords: 
• sedimentary system /
• sandstone genesis sandstone-type uranium deposit /
• Zhiluo Formation /
• Ordos basin /

Abstract: The sandstone structure and scale vary with different depositional systems, and have different contribution to uranium mineralization. According to outcrop research, drilling core analysis, and sand distributed system drawing,we analyzed the lowermember of Zhiluo Formation, northeastern Ordos basin. The results show that the lowermember of Zhiluo Formation is not formed by braided stream in traditional recognition. In fact, it can be divided into the upper and lower sub-members. Although the upper and lower sub-members have well inheritance in provenance and sand distributed direction-which is NW-SE, they have different genesis. The lower sub-member of Zhiluo Formation com-prise braided stream system and braided delta regime, and braided stream delta plain is the main body; the upper sub-member of Zhiluo Formation comp rise meandering river system and meandering river delta regime, and meandering river delta plain is the main body, meandering river delta front take up some space also, which is the result of lake extension to northwest. So, the low sub-member has larger scale and better connectivity, while up sub-member has smaller scale and higher heterogeneity. The practices of sandstone-type uranium exploration also p rove that the ore mainly occurred in low sub-member of Zhiluo Formation. Therefore, the genetic recognition is favorable for the rule summary and space orientation of uranium mineralization.