松辽盆地北部头台地区四方台组地层划分对比及成矿条件分析OA

In recent years,significant progress has been made in the exploration of sandstone-type uranium deposits in northern Songliao basin,with industrial-grade ore bodies successfully discovered in the Upper Cretaceous Sifangtai formation across the Central Sag and Western Slope.This discovery has brought new requirements for the stratigraphic division and lateral correlation of the Sifangtai formation.However,stratigraphic research in this area is currently seldom reported.Based on the exploration results of uranium deposits in northern Songliao Basin and oil and gas drilling,logging,seismic and other data from oil fields,this study systematically summarized the marker layers and key sequence boundaries of the Sifangtai formation,and determined a unified isochronous stratigraphic framework which can divided Sifangtai formation into three sections,and three positive cycles based on lithological and electrical characteristics,corresponding to three fourth-order cycles.On the basis of stratigraphic division and comparison,radioactive anomaly characteristics were compared based on well logging curves and core features,and it was clarified that the Sifangtai formation is the main ore bearing layer,and the bottom sand body is the host of uranium ores.The lower sandstone body of Sifangtai formation exhibits substantial thickness and stable distribution,providing favorable migration pathways and reservoir space for mineralizing fluids.Rich in mud and organic matter,the sandstone body serves as a reducing medium and adsorbent,creating favorable geological conditions for uranium mineralization and promising exploration prospects.This achievement not only provides critical stratigraphic evidence for Sifangtai formation but also offers robust theoretical support for the metallogenic prediction of sandstone-type uranium deposits in northern Songliao basin.