Research On Cretaceous-paleogene High-resolution Sequence Stratigraphic Division,Correlation And Genetic Control In The Bayannaoer Sag

Bayannur sag of Linhe District Depression is located in the west of Hetao Basin,which is an important oil and gas reservoir development zone in China.It is a continental fault basin formed by many tectonic evolution,the favorable exploration zone is not clear.In this thesis,high resolution sequence stratigraphy is divided and correlated in the study area by structural geology,classic sequence stratigraphy and high resolution sequence stratigraphy theory and research methods,the control mechanism of palaeostructure,palaeoclimate and palaeohydrology on the development of sequence is discussed,which will provide reference for future oil and gas explorationThree sedimentary facies,six sedimentary subfacies and 13 sedimentary microfacies were identified in the Guyang-Linhe District formation of the Bayannur Depression by lithologic assemblage,seismic facies,logging facies and paleontological fossils,the main sedimentary facies are braided river delta front and shore-shallow lake,and the target zone is divided into SQ1-8 tertiary sequence by the analysis of multi-well logging curves,seismic profiles and sedimentary facies,except for the Guyi Formation,each member of the Guyang-Linhe District formation corresponds to a tertiary sequence and the Guyi member corresponds to SQ2-3 sequences.Each sequence can be divided into a lake transgression system tract(EST)and a high stand system tract(HST).The38 short-term base-level cycles rising or falling are further divided by using the fine analysis of logging curves and wavelet analysis,and the high-resolution sequence stratigraphic framework is successfully set up and classified for comparative analysis.The development of sequence stratigraphic framework in Bayannur depression is mainly controlled by palaeostructure,palaeoclimate and palaeohydrology,among which regional tectonic activity is the main controlling factor for the development of the third-order sequences,Short-period episodic structures also contribute to the genesis of high-resolution sequences in the Bayannur depression.The lithologic combination facies,logging curve facies and wavelet curve are selected as the substitution index for the paleoclimate inversion of Mirakovi(?) cycle,the paleoclimatic inversion was carried out by using the geochemistry data,such as Sr/Cu,Rb/Sr,Sr/Ba ratios,etc.,the genetic mechanism of the corresponding short-term base-level cycles is analyzed and it is concluded that the paleoclimate and palaeohydrologic changes caused by the periodic changes of Earth orbit play an important role in the development of high-resolution sequence stratigraphy in the Continental Rift Basin.There are 51 figures,7 tables and 86 references in this thesis.