Vestiges of Underplating and Assemble in the Central North China Craton
Based on Noise Tomography
Abstract
The study region is located in the central part of the North China
craton (NCC). We use one-year continuous waveforms of the vertical
component from 112 broadband seismic stations and obtain the group
velocity dispersion curves of Rayleigh waves for different periods
through single station data preprocessing, cross-correlation
calculation, stacking, group velocity dispersion measurement and quality
evaluation. We then use the surface wave tomography method to obtain the
Rayleigh wave group velocity distributions at 9-40 s in this area.
Finally, the S-wave velocity structures at depths of 0-60 km are
determined by pure path dispersion inversion. The results show that the
crustal structure of the Eastern Block is different from those of the
Western Block and the Trans-North China orogen. The lower crust of the
Eastern Block shows a high-velocity S-wave anomaly, which may be related
to magma underplating in the lower crust induced by an upwelling mantle
plume. From the surface to the top of the mantle, the S-wave velocity of
the Western Block decreases gradually, and the crust of the Trans-North
China orogen shows a relatively high S-wave velocity. The results
characterize the S-wave velocity structures of the different geological
units and have important scientific significance for understanding the
destruction of the NCC.