Lithospheric structure beneath the central and western North China Craton and adjacent regions from S-receiver function imaging

Summary To elucidate the nature and extent of the lithospheric modification in the central and western North China Craton (NCC) and adjacent regions, we used the wave equation–based migration technique of S-receiver function on teleseismic data collected from 314 broadband stations in this region to image the lithospheric structure. Incorporating data from previous lithospheric structure studies, we obtained unprecedented high-resolution depth maps of the lithosphere–asthenosphere boundary (LAB) and mid-lithospheric discontinuity (MLD) in the NCC. Our results show more detailed variations of the lithospheric thickness in the central and western NCC and adjacent regions, which ranges from 100 to >170 km, in marked contrast to the thinned lithosphere (60–100 km) in the eastern NCC. Despite its generally thick lithosphere (>130 km), the Ordos Block shows a concordant N–S difference from the surface to deep lithosphere with a boundary at the latitude of 37–38°N. The central NCC is laterally heterogeneous in the lithospheric structure, and the thick lithosphere (∼160 km) in the south is interpreted as a remnant cratonic mantle root. The central Qinling Orogenic Belt preserves a thick lithosphere (∼150 km), which may block the asthenospheric flow driven by extrusion of the Tibetan Plateau to the west of the NCC. Moreover, a negative MLD is widely identified at the depth of 80–110 km within the thick lithosphere, which corroborates the global existence of the MLD in continental regions. The consistence in the depth of the MLD and the shallow LAB in the eastern NCC supports the conjecture that the MLD may have played an important role in the lithospheric modification of the eastern NCC.