Fault System And Its Control On Sedimentation In Jinshan Area Of Lishu Fault Depression

The Jinshan area is located in the southern part of the Lishu fault depression in the Songliao Basin.To the west is the Sangshutai boundary fault,which has the characteristics of a half graben with steep west and gentle east.At present,many wells have found good oil and gas displays in fault depressions,showing great potential for oil and gas exploration;however,the structural systems and evolutionary features of this area have not been studied more precisely and systematically.The restriction law of layer distribution is not clear yet.This paper takes the Jinshan area fault depression as the main research object,based on regional geology,3D seismic,drilling,logging data,etc.,using sedimentary petrology,seismic sedimentology and tectonic geology theory and method technology to develop the characteristics of structural system evolution,Source transport system and tectonic movement control on sedimentation,etc.The tectonic activities in the Jinshan area during the rift period were active and the process was complicated,mainly developed near-north-south extending fault systems and north-east-southwest fault systems with strike-slip properties.The interaction of the two types of fault systems jointly controlled the paleomorphological pattern.It not only controls the uplift of the stratum,but also controls the changes of the stratum.The uplifting in the southern part of the stage caused the stratum to be truncated and extinguished in the south,and the erosion intensity gradually decreased towards the east and became overlying and extinct.The Shahezi Formation and Yingcheng Formation of the fault depression system experienced three-stage and two-stage tectonic uplift movements,respectively.Seismic facies and provenance composition analysis show that the erosion of the stratum makes this area an important provenance area for the Lishu rift,which transports a large amount of sediment into the basin.The southwest uplift area on the west side of the area has fewer supplies and has less impact on the basin deposition.The tectonic activities and the resulting geomorphological characteristics have shown a certain control effect on the distribution of sedimentary facies belts,forming the development of fan-delta-lake sedimentary systems in the basin.In the early stage of the Shahezi Formation,the tectonic activity was weak,the formation in the southeast uplift was relatively stable,there was no massive erosion,and the source supply was insufficient.The movement was active,the southeast uplift experienced three stages of uplift and erosion,the source supply was sufficient and the influence range was large,the sedimentary center moved northwestward,and the sedimentary facies were mainly fan delta plain and fan delta front.Weakened,the supply of provenance is reduced,and the sedimentary facies are dominated by the fan delta front.