Crustal structure beneath NE China imaged by NECESSArray receiver function data

Abstract

We analyzed tens of thousands of receiver-function data recorded by 185 broadband seismic stations to study the crustal structure beneath the northeast China. Moho depth and average crustal Vp/Vs ratio were measured at each station using the H–κ grid searching technique. For stations located above unconsolidated sediments, we applied the H–β method to remove strong shallow reverberations and generate subsurface receiver functions that allow for effective H–κ analysis. The measurements show that the Songliao basin has a relatively thin crust (∼31 km), and the Moho depth increases significantly from southeast (∼27 km) to northwest (∼35 km). The northwestward tilting of the Songliao basin may suggest that it was initiated by lithospheric flexure due to the load of the Great Xing'an range in the Jurassic before the large-scale extension in the Cretaceous. Moho depth varies from 26.7 km to 42.3 km across the study area, with the shallowest and deepest Moho being located at the eastern flank of the Songliao basin and the Great Xing'an range, respectively. The Moho depth correlates well with the surface topography in the western part, but not the central and eastern parts of the study area. The residual topography computed based on the Airy's isostasy model indicates that the high topography at the eastern flank of the Songliao basin, the Changbaishan volcanic center, and the southern end of the Great Xing'an range is likely dynamically supported by the upper mantle.