江苏盐阜拗陷晚白垩世浦口组沉积相与沉积演化

为系统探讨区内晚白垩世浦口组沉积相类型、沉积特征,深入研究了浦口组各亚段沉积相平面分布及盆地沉积演化规律。研究表明,浦口组主要发育冲积扇、扇三角洲和湖泊三种主要沉积相类型。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、半深湖或盐湖相沉积;自下而上由冲积扇沉积逐渐变为扇三角洲或滨湖,至浅湖、半深湖或盐湖相,再到浅湖相沉积。晚白垩世浦口组沉积时期,盆地演化过程可划分为初、早、中和晚四个时期。不同时期、不同地区的沉积特征表现各异,但总体表现出拗陷具有由小到大,再缩小的发育特点。

Sedimentary Facies and Evolution of Late Cretaceous in the Yanfu Depression from Jiangsu Province

The types of sedimentary facies and sedimentary characteristics in Pukou Formation of Late Cretaceous System in Yanfu Depression are systematically analyzed, and the planar distribution of sedimentary facies in the members of Pukou Formation and the laws of facies evolution are studied in detail. The conclusions show that Pukou Formation is mainly comprised by alluvial fans, fan deltas and lacustrine facies. In the basin, from the margin to the center, the facies developed from alluvial fans, gradually to fan deltas or lakefront facies, shallow take facies, semi deep lake facies, or saline lake facies; from the bottom to the top, the facies gradually changed from alluvial fans to fan deltas or lakefront facies, to shallow lake facies, semi deep lake facies or saline facies, finally to shallow lake facies. The Pukou Formation can be divided into four stages: initial stage, fore stage, metaphase and terminal stage. The sedimentary characteristics are correspondingly different in various stages and areas. But, as a whole, the Yanfu Depression changed from narrow to wide, and then to narrow.