Publication Date:
2013-04-16
Description:
[1] We imaged detailed 3-D crustal and uppermost mantle seismic structures in the North China Craton from inversion of Rayleigh wave phase velocity at periods of 6 to 143 s. The phase velocities were obtained from a combination of ambient noise and teleseismic surface wave tomography and then the phase velocities were inverted to S -wave velocities. The results show that both Huabei Basin and Ordos Block have markedly rapid variations in both crustal velocities and the Moho depth. Huabei Basin has a thin (31–34 km) crust with low-velocities while Ordos Block has a thick (~40 km) crust with high velocities. We also estimated the lithospheric thickness from the inverted S -wave velocities using a simple S -wave velocity/temperature relationship. Huabei Basin was imaged as a low S -wave-velocity anomaly in the uppermost mantle with very thin lithosphere (~ 65 km), while Ordos Block was revealed as a high S -wave-velocity anomaly with rather thick lithosphere (〉 120 km). These results indicated that Huabei Basin and Ordos Block have different thermal and/or chemical properties and had experienced different mantle processes and evolution histories since the Cenozoic. Furthermore, slow S -wave velocities and very thin lithosphere (~ 65 km) were also found beneath Hetao and Weihe rifts bounding Ordos Block at north and south, respectively. However, Shanxi Rift-the boundary between Huabei Basin and Ordos Block-had a much thicker and higher-velocity lithosphere than Hetao and Weihe rifts.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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