Structural Activity Analysis Of Faults In The Southeast Of Songliao Basin

Songliao basin is a large Mesozoic composite sedimentary basin with fault and depression structure in east China,and it is rich in oil and gas resources.At the same time,due to the thick overburden and few outcrops,the study of quaternary geology is not high,especially the active structure,which has not been systematically studied so far.In recent years,mid-strong earthquakes of magnitude 5 or so occurred frequently in the southeast margin of the basin.Therefore,the study on fault activity in the study area is of great significance for seismic planning.The study area is located in jilin oilfield.The study area is rich in oil reflection seismic exploration data and drilling data to determine the distribution characteristics of major faults in the area.In order to accurately determine the quaternary activity of faults,shallow reflection seismic exploration and cross-fault drilling were carried out in combination with the dating data to determine the quaternary activity of faults.Based on the careful analysis of the reflection seismic exploration section,the growth strata near the fault zone are identified.Based on the growth strata,the time and stages of the inversion structures in the southeastern part of the basin are discussed.In order to explore the problems of fuyu section of the second songhua river fault and seismogenic fault in the 1119 earthquake,the oil reflection seismic data of tuohaotai area and halamodu area in the study area were collected and the shallow detection work was carried out to discuss these two problems.On the basis of field geological investigation and data collection,by collecting the research area of 2 d and 3 d oil reflection seismic exploration data,determine the research area,there are mainly four deep fracture,fault,no fault,red hills,solitary shop in fuyu north fracture,fracture and the fracture distribution in the songliao basin in the eastern part of boundaries of tectonic units.The oil seismic reflection section,shallow reflection section,cross-fault drilling and chronology data of four faults are analyzed.Fuyu north fault is a middle pleistocene fault.The goudian fault is a late pleistocene active fault.The inversion structure of songliao basin since the late cretaceous is a process of regional stress from tension to thrust.Through careful analysis,two sets of growth strata formed at the same time with inversion structure in fuyu north fault zone were identified.The lower part of the growth strata is a fold-type growth strata,which belongs to the second to third member of the qingshankou formation of the lower cretaceous,and the growth strata are supersuperimposed,which reflects that the deposition rate is higher than the uplift rate of the structure.The upper growth stratum is also a fold-type growth stratum,which dates from the da ’an formation of tertiary system and shows overlying growth,reflecting that the deposition rate is higher than the tectonic uplift rate.Based on the characteristics of the above two-stage growth strata,the inversion structure of fuyu north fault since late cretaceous is composed of two stages,which are the lower cretaceous qingshankou formation and tertiary daan formation.A set of growth strata has been identified in gudian fault.The formation time of the growth strata begins from the early renewal taikang formation.This set of growth strata is distributed in the footwall of the goudian fault.The strata overlap from the wing to the top of the fold and then overlap.Considering that the deposition rate(Rs)of the growth strata of the taikang formation is > and the uplift rate(Ru)of the gudian fault in the taikang formation is determined to be < 0.15mm/a by means of shallow detection and chronologic test.The baitushan formation in the late early pleistocene is a regressive growth stratum of the gudian fault,and the Ru(uplift rate)of the baitushan formation is greater than 0.091mm/a.The paper also discusses fuyu section of the second songhua river fault and the epicentre and seismological fault of the 1119 earthquake.The petroleum reflection seismic profile of the fuyu section of the second songhuajiang fault was collected,and no evidence of the existence of the second fuyu section of the second songhuajiang fault was found.In view of the surface outcropping fault in the halamodu area,which is considered to be the surface outcrop in the northern section of fuyu of the second songhua river fault,we have carried out detailed geological survey and exploration in this area,and found that the buried strata in this area have good continuity and no obvious fault fault.Therefore,the second fuyu section of the songhua river fault does not exist.1119 years ago in history,according to the big Jin Guozhi guo 6 delighted many customers and major seismic area of influence between the tower tiger city and county agriculture of jilin province,based on the earthquake seismic intensity distribution(Wu Ge etc.,1988),to determine the fracture,the regional distribution of fracture is isolated store isolated store fracture is the active faults since late pleistocene,possess the ability of a strong earthquake with a magnitude 6 delighted many customers(Shao Bo etc.,2016).Based on the above analysis,it is concluded that the goudian fault is the seismogenic fault caused by the golos 63/4 earthquake 1119 years ago.This paper gives the distribution of fault structure in the southeast of songliao basin,and determines that there are four main faults in the southeast of the basin: fuyu north fault,gudian fault,da ’an fault and honggang fault.The quaternary activity of four faults is determined: honggang fault and da ’an fault are pre-quaternary fault,fuyu north fault is quaternary fault and gudian fault is late pleistocene active fault.The two-stage growth strata of fuyu north fault were identified and the two-stage inversion structures in the southeast of the basin were identified by the growth strata.A set of growth strata since the quaternary of gudian fault has been identified.According to the reflection seismic profile and geological survey,it is considered that the north section of fuyu of the second songhua river fault does not exist.It is proved that tuohaotai(longkeng)is not the epicenter of the 63/4 earthquake in guerros 1119 years ago,and the gudian fault is considered to be the seismogenic fault of this earthquake.