Study On The Sedimentary Characteristics And Genetic Types Of Conglomerate Body Of Es₄-Es₃ In The Steep Slope Belt Of Langgu Depression

Daxing Conglomerate is located on the downthrown side of Daxing Fault in the western.Langgu Depression,and it has much higher exploration potential.However,due to the lack of in-depth study of sedimentary background,genetic type,sedimentary characteristics and deposition of the times,the oil and gas exploration in Daxing conglomerate has not made a breakthrough.In this paper,the geological background,genetic types and sedimentary characteristics of the Daxing conglomerate in the third member of the Oligocene Shahejie Formation(Es3)in the Langgu Depression were studied in detail based on seismic profiler,logging,cores,petrographic thin-sections.Daxing Conglomerate was mainly developed in the intensively faulting period of Langgu Depression.The structure evolution and fault activity controlled the formation and distribution of Daxing Conglomerate: The pre-Paleogene tectonic movement controlled the source types of conglomerate,the Paleogene tectonic movement controlled the vertical distribution of conglomerate,and the episodic activity and migration controlled the genetic types and evolution.On this basis,determine the classification scheme of Daxing conglomerate deposition times,Es4-Es3 development Daxing conglomerate will be divided into a total of eight times.On this basis,summarising the method of divide and sedimentary characteristics of the deposition times.At the same time,the study found Daxing conglomerate develops three sets of conglomerate group on the downthrown side of Daxing Fault: Caiyu Conglomerate group,Jiuzhou Conglomerate group,Guan Conglomerate group.Based on the results of previous studies,combine the core data with the petrographic thin-sections,we can find that the composition,structure and material sources of the Conglomerate group from different areas have obvious difference.Based on the depositional setting,three genetic models of conglomerate have been set up depending on cores,seismic facies and electro facies,including gravity flow channel,grain flow nearshore subaqueous fan and mud flow nearshore subaqueous fan.Finally,based on the above research,draw out each of times Daxing conglomerate sedimentary phase plan.