Crustal Seismic In The Northeast Of China

The study area of this article is centered at38.5°-52.5°North latitude and120°-134.5°East longitude，that is located in Northeast China.This area includes the northern margin ofthe North China plate，Songnen-Zhangguangcailing microplate，Greater Khingan Rangemicroplate，Ergun microplate，xingkai microplate and Jiamusi microplate and other majorstructure units that are divided by the Greater Khingan Range orogenic belt, ChangbaiMountain orogenic belt and the Tanlu fault.In order to understand structural system anddynamics of the study area,we need to seismology means to obtain the deep structure of theearth.At present,the H-kapaa technique is the one of the more effective way to obtain crustalthickness and Poisson’s ratio.Using the teleseismic data recorded by seismic stations with142broadband on theHeilongjiang Province, Jilin Province, Liaoning Province and the eastern part of InnerMongolia Province,we can get the distribution characteristics of The crustal thickness, Vp/Vsand Poisson’s ratio in the study area by the means of H-Kapaa receiver function. The crustalthickness of the stations by H-Kapaa receiver function show that the crust over northeasternchina is intense. The obtained crustal Poisson’s ratios are large,it indicates that The immediatePacific plate leading edge with a complex crustal structure probably suffered the more intensecrustal thinning related with the subduction of the Pacific plate or the mantle upwelling. InLiaohe plain area，the crust thickness is the thinnest, and the change of the poisson’s ratio isrelatively complex. The crustal thickness has obvious differences between the east and thewest. these could show that the crust in the Northeast may exist the movement process ofsettlement, or vertical erosion. the crustal thickness of inner Mongolia Province’s eastern areais thick.it become gradually thicken with the higher elevation. The change of the poisson’sratiothe is relatively stable. The crustal thickness had obviously thinning from the west to theeast beyond the North South gravity gradient belt.In the east of Heilongjiang Province,thecrustal thickness has thickened. And the poisson’s ratio changes obviously. This differencemay be due to the subduction of the Pacific plate. The crustal thickness of the Yanshan area isrelatively thick,and it has significant thickening trend from the east to the west. The range ofpoisson’s ratio is large. The region may be affected by the Central Asian orogenic beltaccretion and subduction of the Pacific plate, Thus its crust has the more complextransformation.In order to further understand the distribution of the crustal thickness and Poisson’sratio,we selected the area from the east of Yanshan to the east of Liaoninag Province, theYilian-Yitong fault zone and Dunhua Mishan fault zone of Heilongjiang Province and itssurrounding areas to study. Through the study of the crustal thickness and Poisson’s ratio onthe two representative region，as a whole,we get that the crustal thickness from the easternside of Yanshan to the east of Liaoning Province is going to get thick before it get thin. Seeits structure, with The lithosphere pull up thinning on different degree, The crustal thickness tend to thin in the eastern margin of Yanshan area. This reflects the differences of The East-West crustal thickness in Northeast China. The crustal thickness distribution of theHeilongjiang area in the Yilan Yitong fault zone and Dunhua Mishan fault zone and thesurrounding area indicate that the crustal thickness trend to thick from West to East.