浅水曲流河三角洲前缘沉积特征及模式OA

Based on data from cores,thin sections,logging-while-drilling,and 3D seismic surveys,this study analyzes the sedimentary characteristics,distribution,and models of the shallow delta front subfa-cies of the Penglaizhen Formation in the Baimamiao Area.The results indicate that the region is pre-dominantly composed of fine-grained sediments,with locally identifiable gravel-sized clastics,catego-rized into three lithofacies:conglomerate,sandstone,and mudstone.The flat terrain,arid and hot cli-mate,and the developmental features of sand bodies characterized by"thin-layer stacking and multi-phase superposition"are noted.Storm deposits identified in cores suggest shallow delta front sedimenta-tion during the Penglaizhen Formation period,influenced by storm disturbances.From Peng 3 to Peng 4 members primarily developed microfacies such as subaqueous distributary channels,mouth bars,and sheet sands.Mouth bars often appear as remnants,frequently overlaid by subaqueous distributary chan-nels,while sheet sand bodies are widely distributed,forming a shallow delta front sedimentation with a striped-branching network pattern in plan view.The sedimentary model is primarily controlled by fre-quent lake-level fluctuations and fluvial-littoral reworking,exhibiting an evolutionary pattern from pro-gradational to aggradational-progradational.These findings provide references for understanding sedi-mentary facies in the Baimamiao Area,as well as exploration and development in the Penglaizhen For-mation of Western Sichuan and similar regions.