Study On The Paleogene Dongying Formation Sequence Stratigraphy And Depositional System In Shinan Slope Of Bohai Sea

Based on the theories of continental sequence stratigraphy and sedimentology, this paper examines the sequence stratigraphy,sedimentary system,lithofacies paleogeography and source-reservoir-cap assemblages of Dongying formation to Paleogene in Shinan slope by means of logging, seismic and geologic and other disciplines.Firstly, according to regional tectonic and sedimentary background information, and drilling / logging and seismic data, the depositional system in Shinan slope of the Paleogene Dongying Formation is divided into five categories of depositional system, 13 sedimentary subfacies and 16 sedimentary microfacies.And Including three levels of sequence boundaries, three third-order sequences in this paper .And this study makes a in-depth discussion of the sequence, the characteristics of systems tracts, distribution and controlling factors of development,and establishes sequence stratigraphic framework of high-precision of Shinan slope, makes a summary of sequence stacking pattern and development law, and proposed large-scale development of braided river delta in paragraphs of Dongying formation, shallow sediments and middle depth lacustrine, and large-scale highstand sublacustrine fan of Dong'er sequence on both sides of Shinan slope.According to the principles of map compilation, the task and the purpose of the study ,This paper makes Sequence-based lithofacies and paleogeography mapping of the Paleogene strata in the study area, by making use of system tracts as the basic mapping unit. And based on the"single factor analysis and comprehensive mapping method",and considering the various factors such as structural components of rock, sedimentary structures, palaeontological features and characteristics of well logs which can reflect the sedimentary environment, this paper makes some sequence-based compilation diagrams on sedimentary facies of Paleogene in Shinan slope that is a planar distribution diagram within a sequence stratigraphic framework and a detailed description of the different system tracts lithofacies paleogeography and evolution.The study summarizes that E3d3 sequence whose main deposition is exogenous deposition mainly developes in the depression zone semi-deep and deep lacustrine settings;However, it mainly developes in the ramp zone braided-river delta deposition and shore-shallow lacustrine sand bar sediment,and E3d2 whose main deposition is exogenous and distal deposition mainly developes large-scale braided-river delta deposition, accompanied by large-scale slump turbidite fan deposition, and braided delta front sand deposits.