Using Receiver Function To Research The Crust-mantle Structure In Southeast China

Although P-wave receiver function method has become a routine method to detect the Moho and discontinuities in the upper mantle beneath seismic stations,Ps converted phases from lithosphere-asthenosphere boundary(LAB)in P-wave receiver function are easily submerged due to the interference of multiple waves in the crust.Compared with the Pwave receiver function,the S-wave receiver function uses the Sp converted phases,which have lower frequency.It can be used to study the gradual transition zone structure.Sp converted waves is the precursor of S wave and all the multiples occur after S wave.This advantage makes it separates the primary converted phase from the multiples and will not overlap with the multiple waves in the crust and be submerged.Therefore,the S-wave receiver function is more suitable for the studying of the depth of LAB.In this paper,the P-wave receiver function method is realized by using teleseismic events with epicenter distance of 30-90° and magnitude greater than 5.0 from seismic data from 89 permanent stations in the national network of Southeast China from January 2016 to December 2016.The Moho depth below each station is obtained by H-? stacking and CCP stacking.The S-wave receiver function is carried out by using teleseismic events with epicentral distance of 55-85°and magnitude greater than 5.5 from seismic data of 183 permanent stations in the national network of Southeastern China from January 2016 to December 2016,and 68 broadband portable stations by Chinese University of Geosciences(Beijing)and the Chinese Academy of Geological Sciences from June 2012 to June 2016,respectively.The depth of the lithosphere-asthenosphere boundary(LAB)in the study area was obtained by CCP(common conversion point)stacking from S-wave receiver functions.P-wave receiver function results show that the Moho depth in the studying area is about 30 km,and S-wave receiver function results show that the depth of LAB in the study area is 60-80 km showing the thinning of lithosphere in the southeastern region of China.The lithospheric thinning maybe is due to the large-scale upwelling of asthenosphere and the subduction of the Pacific plate under Eurasia.The specific tectonic evolution process in southeastern China needs to be further studied in combination with other geophysical methods,tectonic geology and petrogeochemical methods.