Lithospheric structure beneath the central and western North China Craton and the adjacent Qilian orogenic belt from Rayleigh wave dispersion analysis

摘要: Abstract We used surface wave tomography to image the lithospheric S-wave velocity structure along a linear seismic array across central and western North China Craton (NCC) adjacent Qilian orogenic belt (QB). Using waveform data from 8 earthquakes collected at 60 broadband stations, Rayleigh phase velocities were measured periods of 20–120 s subsequently inverted for reliable 200 km depth. Distinct structures marked lateral variations revealed beneath study region, correlating well with regional geological tectonic features. The average depth is ~ 4.45 km/s, ~ 1% lower than that in model AK135. High > 4.45 km/s are most pronounced stable Ordos Block (western NCC). However, which observed high body extends varies significantly laterally. It deepest (~ 200 km) under eastern Ordos, becomes shallower on both sides array. maximum gradually shallows westward reaches ~ 110 km near edge Ordos. This variation suggests coexistence preserved modified lithosphere decreases rapidly eastward by > 80 km over distance