Study On The Sedimentary System Of The Third Member Of Paleogene Funing Formation In The Subei Basin

Based on the theory of sedimentology,the regional geology,core observations,well log,seismic data,SEM photos and testing data,the dissertation studied the third member of Paleogene Funing Formation in the Subei Basin.The provenance system was well understood and the properties of the provenance rocks were restored.The types of sedimentary systems were reclassified and the depositional model was re-established.The distribution characteristics and controlling factors of the sedimentary systems were discussed.The dissertation means to provide new ideas and directions for the exploration of the old oilfield.The main achievements are as follow:(1)There are 6 main provenance areas building the third member of Funing Formation of Subei Basin.(?,?)Jianhu Uplift provided the sources respectively to the south and north.(?)Zhangbaling Uplift provided the source eastward to the Western Jinhu Sag.(?)Sunan Uplift provided the source northward to the Southern Gaoyou Sag.(?)Binhai Uplift provided the source southward to the Funing Sag.(?)Eastern Lusu uplift provides the source eastward to the Lianbei sag.Subei Basin belongs to an active continental margin tectonic setting.The provenance is derived from the re-cycled belt formed by the inter-plate collision and subduction.(2)The sedimentary system of the third member of Funing Formation in the Subei Basin was divided into five types: river-dominated delta system,wave-dominated delta and beach bar system,nearshore deformed beach bar system,nearshore subaqueous fan system,storm depositional system.This paper argued that the river-dominated delta system was mainly developed in Yancheng Sag on the north side of Jianhu Uplift.The south side of Jianhu Uplift was dominated by wave-dominated delta and beach bar system and nearshore deformed beach bar system.It was the first time to explain the nearshore subaqueous fan system in the southern part of Gaoyou Sag.(3)The depositional model of the third member of Funing Formation in the Subei Basin was re-established.South winds prevailed in the Subei Basin.The south part of the Jianhu Uplift,Funing Sag and Lianbei Sag were located in the windward gentle slope belt,and were dominated by the wave-dominated delta and beach bar system and nearshore deformed beach bar system,where the waves were strong and the shallow lake was widely distributed.Western Jinhu Sag and Yancheng Sag were located in the leeward side,and were dominated by the river-dominated delta system,where the waves were relatively weak.Southern Gaoyou Sag and Southern Hai'an Sag were located in the steep slope belt,and were dominated by nearshore subaqueous fan system,with paleogeographic features of large height difference,near source,deep water.In the vast half-deep lake environment,the thin layers of storm depositional system were developed.(4)The distribution of sedimentary system was controlled by multiple factors,which could be summarized as paleogeomorphology,ancient wind(wave),ancient water depth and source supply conditions.