Research On The Mesozoic Sequence Stratigraphy Framework And Sedimentary System Of Minjiang Sag In The East China Sea Shelf Basin

East China Sea Shelf Basin is a Mesozoic-Cenozoic superimposed basin located in the East China Sea continental shelf.During the past 50 years,the exploration in the Cenozoic strata has obtained great break through,whereas the basic geological study in the Mesozoic strata is weak,which restricted the oil and gas exploration.Previous views have shown that the Mesozoic strata in Minjiang sag have great potential of oil and gas resources.This thesis synthetically uses the seismic data,drilling data,logging data and regional geological data to study the characteristics of sequence stratigraphy and sedimentary system of the Minjiang sag and its surrounding region.We redefined the sedimentary environment of the Mesozoic strata in Minjiang sag via selective analysis on the drilling data.We defined the distribution law of sedimentary system inside the sequence framework combined with the result of seismic facies analysis and established the depositional model of the work area.We divided the whole strata into 5 tectonic sequence and the Mesozoic strata were divided into 2 tectonic sequence.We identified the third-order SB on the well and the Mesozoic could be divided into 7 third-order sequence.The thesis only established the secondary order sequence in the whole area limited by the quality of seismic data.Predecessors thought that Mesozoic was mainly composed of continental lacustrine deposition in the Minjiang sag.We redefined the sedimentary environment of the Mesozoic strata in Minjiang sag via selective analysis on the drilling data.We found sedimentary facies symbol of marine sediments in the core such as Herringbone cross bedding,Glauconite,Coccolith,Calthrop and so on.Geochemical analysis also shows that the organic matter comes from the lower Marine plankton.Therefore we considered that the sedimentary environment of the south of East China Sea Shelf Basin was offshore deposition.We established the Seismic facies-sedimentary facies interpretation chart of the work area via the analysis of core facies and seismic section.The result shows that the main types of sedimentary facies are alluvial fan facies,the delta facies,the fluvial facies and neritic facies.The main types of sedimentary system are the volcanic debris – alluvial system and the volcanic debris –offshore system.We draw the distribution map of the sedimentary system of the Jurassic and Cretaceous respectively.By studying the the formation and evolution history of Yandang low uplift and Taibei low uplift,we summarizes the depositional model of the Jurassic and Cretaceous combined the research result of sedimentary system.We also pointed out that the formation of the Yandang low uplift at the end of the Jurassic has a significant impact on the sedimentary pattern of the work area.