The Sequence Stratigraphy And Sedimentary Facies Of Ordovician Carbonate Of Dongpu Depression

Taking the depositional formations of Ordovician of Dongpu Depression as the research subject and the sequence stratigraphy,sedimentology as the theoretical directions,based on the detailed analysis on the data of cores,well logging,geochemistry and outcrop observation,analysis on the sedimentary facies and the sequence stratigraphy of the research area.Research suggests that: the sequence stratigraphy of Ordovician in the research area can be divided into two sequences as SS1 and SS2,moreover the SS1 can be further divided into two cycles,which respectively correspond to Yeli formation and Liang Jiashan formation.The SS2 can be divided into three cycles,which respectively correspond to Xia majiagou formation,Shang Majiagou formation and Fengfeng formation.Using single factor and multifactor comprehensive analysis,draw sedimentary facies maps.Research suggests that there are three sedimentary facies such as open platform,restricted platform,evaporation platform in the research area.Twelve sedimentary microfacies such as dolomitic flat,gypsum-bearing dolomitite flat,grain beach facies developed in this area.Yeli formations mainly developed restricted platform facies;Liang Jiashan formation mainly developed evaporate platform facies.Due to frequent changes of the sea level,sedimentary facies of Xia Majiagou formation and Shang Majiagou formation have the basic characteristics that restricted platform and open platformwhich emerged interactly.Fengfeng formation mainly developed open platform facies.