Sedimentary Facies and Evolution of Late Cretaceous Taizhou Formationin the Yanpu Depression in North Jiangsu basin
Mu Rong (Jiangsu Oilfield Branch Company, SINOPEC,Nanjing 210016)
The types of sedimentary facies and the sedimentary characteristics in Taizhou Formation of Late Cretaceous System in Yanfu Depression are systematically analyzed,and the planar distribution of sedimentary facies in the members of Taizhou Formation and the laws of facies evolution are studied in detail. The conclusions show that Taizhou Formation is mainly comprised of alluvial fans,fan deltas and lacustrine facies. In the basin,from the margin to the center,the facies is developed from alluvial fans,gradually to fan deltas or lakefront facies,shallow water lake facies,half-deep water lake facies; from the bottom to the top,the facies gradually changed from alluvial fans to fan deltas or lakefront facies,to shallow-water lake facies,hemi-deep-water lake facies,finally to shallow- water lake facies.The Taizhou Formation can be divided into two stages: early stage and later stage. It is developed as fault lacustrine basin at the early stage,characterized by alluvial fans and fan deltas; at the later stage,it is developed as depressive basin with lake surface increasing,the depth of the lake is enhanced,the sediment area is enlarged,and shallow-water lake facies or half-deep water lake facies are developed. Thus,lake surface dropped and granularity of sediment become coarser. The sedimentary characteristics are correspondingly different at various stages and areas.But as a whole,the Yanfu Depression is changed from narrow to wide,and then to narrow.
【CateGory Index】： P534.53