Crustal structure across the Yanshan belt at the northern margin of the North China Craton

We applied an integrated receiver function imaging technique to the teleseismic data from 54 NCISP-III broadband seismic stations to study the fine-scale crustal structure beneath the eastern Yanshan belt (YSB) and adjacent areas at the northern margin of the North China Craton (NCC). The robustness and reliability of the resultant crustal image were noticeably improved by achieving imaging consistency between common conversion point stacking and waveform inversion of the receiver functions. Our imaging result revealed substantial lateral heterogeneities in the crust of the study region, as displayed by the undulating intra-crustal interfaces, highly varying upper-, middle-, and lower crust thicknesses, and interlayers of low and high velocities. The crustal structure of the YSB is characterized by significant structural variations together with a sharp Moho, a thin-to-normal crust and a lower crust with lower velocity and normal thickness. It differs markedly from the Bohai Bay basin and the Taihang Mountains within the interior of the NCC. The distinct features and structural complexity of the YSB might be attributed to the complex tectonic history of the region, especially the multiple phases of contraction and possible occurrence of crustal delamination, which is in large contrast to other subregions of the NCC where tectonic extension likely dominated the crustal deformation since the late Mesozoic.