南黄海盆地南部坳陷古近系阜宁组沉积相分析

Sedimentary facies of the Paleogene Funing Formation in the south depression of the South Yellow Sea Basin

南黄海盆地南部坳陷是该盆地最具勘探突破潜力的地区,有8凹4凸,结构复杂。其中古近系阜宁组为1套厚度超1 km的湖相砂泥岩地层,可分为4段,是最重要的烃源岩。综合应用测井、岩芯、地震剖面、古生物资料以及与苏北盆地进行对比,在南部坳陷阜宁组共识别出3种主要沉积体系:湖泊、三角洲、碳酸盐台地。南部坳陷在阜宁组时期是中国东部一个大型的坳陷型湖盆,阜二段、阜四段沉积时期是南部坳陷的2次湖泛期,其典型特征为中深湖相发育且满盆发育,不发育边缘相;阜三段沉积时期是上述2次湖泛期之间的1次湖退期,典型特征是滨浅湖分布广泛。同时缓坡带发育大型三角洲,是典型的陆相坳陷湖盆的沉积发育模式。

The south depression possesses the most important petroleum potential in the South Yellow Sea Basin, which contains eight sags and four uplifts and has a complicated structure. The Paleogene Funing Formation, a set of lacustrine sandstone and mudstone, with a thickness of 1 km is the most important source rock in the depression, and can be divided into four members. A comparison of logging, core, seismic profile and paleontology with the Subei Basin suggests that three kinds of sedimentary systems are developed in the south depression, including lacustrine, delta and carbonate platform systems. This depression was a large-scale depression lacustrine basin in the Funing stage ; it underwent two lake flooding periods during the deposition of the second and fourth members of the Funing Formation, featured by well-developed and widespread mid-deep lacustrine facies and no marginal facies; it underwent a lake regression period between these two lake flooding periods in the depositional stage of the third member of Funing Formation, char- acterized by widespread shore：shallow lake facies in the depression and large delta in the gentle slope belt. It is a typical sedimentary model of continental depression lake basins.