The Feature Of Sequence-based Lithofacies And Palegeography During Paleogene Of Northestern Of Liaodongwan Basin

Based on the sequence stratigraphy, seismic stratigraphy, biostratigraphy,sedimentology theory, comprehensive utilization of 3D seismic, well logging, mud logging and core data, the ancient northeast of Liaodong Bay Basin Paleogene Dongying Formation in the sequence, sedimentary system were studied. The Dongying Formation has been developed for three sequences: SQd3, SQd2, SQd1.and the stratigraphic framework has been established by systemically studied of the wells sequence stratigraphic section.The fan delta, braided river delta, meandering river delta, lacustrine and the sublacustrine fan sedimentary system were founded in DongYing area.In SQd3, the lake is vast and semi deep lacustrine deposits are widely founded under fault break zone in the central uplift in the northern part and the southern slope break.In SQd2,Meandering river and Braided River Delta development, During the period of EST Lake area expanded, and the slump sublacustrine fan in the local formation In the HST period,Lake was getting shrinking, began to develop the delta sedimentary system. SQd1 period regional tectonic activity stops basically, Lake area shrinking,large meandering river delta development of western, Eastern and Northern see Braided River Delta; In SQd1 sequence period, the region covering the meandering river, braided river delta and lake sedimentary system.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 third grade 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 northestern of JinChou area, Liaodongwan basin, which also means the plane distribution of sedimentary facies in the sequence framework.In total,Period of SQd3 due to strike slip pull a lake basin caused by the rapid deepening, mainly developed lacustrine depositional system; SQd2 sequence period, rift in relatively weak overall effect and sediment began into the lake, the lake expanding domain period in lake sediments and in the high period development in delta sedimentary system in the body.During the period of SQd1 and tectonic action basically stopped, enter the overallshrinking Lake Basin, the sediment around a lot into Lake Basin, showing the sequence period large area development of Braided River Delta and meandering river delta and fan delta.