苏北盆地盐阜拗陷晚白垩世泰州组沉积相与沉积演化

较为系统地探讨了区内晚白垩世泰州组沉积相类型、沉积特征,深入研究了泰州组各亚段沉积相平面分布及盆地沉积演化规律。研究表明,泰州组主要发育冲积扇、扇三角洲和湖泊3种主要沉积相类型。从盆地边缘到盆地中心,沉积相由冲积扇沉积逐渐变为扇三角洲或滨湖、浅湖、半深湖相沉积;自下而上由冲积扇沉积逐渐变为扇三角洲或滨湖,至浅湖、半深湖相,再到浅湖相沉积。晚白垩世泰州组沉积早期为断陷湖盆发育时期,以冲积扇、扇三角洲发育为特征;晚期为拗陷湖盆发育时期,湖平面持续上升,湖水加深,沉积范围扩大,浅湖相或半深湖相发育,而后湖平面下降,沉积物粒度变粗。

Sedimentary Facies and Evolution of Late Cretaceous Taizhou Formationin the Yanpu Depression in North Jiangsu basin

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.