苏北盆地高邮凹陷古近系阜宁组一段浅水三角洲和滩坝沉积模式*

通过对苏北盆地高邮凹陷古近系阜宁组一段38口取心井的岩心观察和薄片鉴定, 识别出岩性、结构、构造标志, 进一步分析了高邮凹陷阜一段的相标志和沉积展布特征。研究认为其具有浅水三角洲和滩坝相的沉积特征, 其中浅水三角洲可进一步分为浅水三角洲平原和浅水三角洲前缘2个沉积亚相, 前者包括分流河道、河口坝、天然堤3个沉积微相, 后者包含水下分流河道、水下天然堤、支流间湾、河口坝4个沉积微相。在湖平面频繁变化过程中, 浅水三角洲的水下分流河道向湖泊轴心方向推进, 形成多个叠置的朵叶体；而在浅水三角洲侧缘, 由于湖浪和沿岸流的改造, 形成多条沿湖岸线和浅水三角洲呈狭长带状展布的滩坝。在上述研究基础上, 建立了湖平面频繁变化时期浅水三角洲和滩坝混合沉积的沉积模式。

Sedimentary model of shallow water delta and beach bar in the Member 1 of Paleogene Funing Formation in Gaoyou sag,Subei Basin

Based on the core observation and thin section identification of 38 wells drilled through the Member 1 of Paleogene Funing Formation in Gaoyou sag, Subei Basin, it was discovered that the sedimentary facies was characterized by shallow delta and beach bar sedimentary features, which was different from that of previous study. The shallow delta facies could be divided into delta plain and delta front sub-facies. The former subfacies, contained distributary channel, mouth bar and subaqueous natural levee and the latter one included subaqueous distributary channel, subaqueous natural levee, bay between distributary channels and river mouth bar. In the period of lake level fluctuation, the distributary channels of shallow delta|stretched into the center of the lake basin to form several superimposed lobes. While adjacent to the edge of shallow delta, beach bars were distributed in ribbon shape along lacustrine shoreline by the transformation of lake wave and coastal current. Thus, a new type of sedimentary model named shallow delta and beach bar depositional model was set up.