Abstract
39473 Pn travel times are inverted to tomographically image both lateral variation and anisotropy of uppermost mantle velocities beneath China continent. The result indicates that the overall average Pn velocity of uppermost mantle in the studied region is 8.0 km/s and the regional velocity fluctuation varies from ?0.30 km/s to +0.35 km/s. Pn velocities higher than 8.2 km/s are found in the regions surrounding Qingzang Plateau, such as Junggar Basin, Tarim Basin, Qaidam Basin and Sichun Basin. Pn velocities slightly lower than the average are found in western Sichuan and Yunnan, Shanxi Graben and Bohai Bay region. A Pn velocity as low as 7.8 km/s may exist in the region striding the boundary between Guangxi and Guangdong provinces. In general, Pn velocity in tectonically stable region like cratonic platform tends to be high, while that in tectonically active region tends to be low. The regions in compressive setting usually show higher Pn velocity, while extensional basins or grabens generally display lower one. Anisotropy of Pn velocity is seen in some regions. In the southeastern region of Qingzang Plateau the directions of fastest Pn velocity show a rotation pattern, which may be related to southeastward escape of the plateau material due to the collision and compression of Indian Plate to Asia along Himalaya arc. Notable anisotropy also exists around Bohai Bay region, likely indicating crustal extending and possible magma activity therein.
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References
Song, Z. H., Chen, G. Y., An, C. Q. et al., 3D velocity structure of crust and upper mantle beneath China continent and sea region, Science in China (in Chinese), Ser. B, 1993, 23(2): 180–188.
Xu Yi, Liu Futian, Liu Jianhua, Seismic tomography beneath the orogenic belts and adjacent basins of northwestern China. Science in China, Ser. D, 2001, 44(5): 470–480.
Sonder, L. J., England, P. C., Effect of temperature dependent rheology on large-scale continental extension, Journal of Geophysical Research, 1989, 94: 7603–7619.
Nelson, K. D., Zhao, W. J., Brown, J. K. et al., Partially molten middle crust beneath southern Tibet: Synthesis of project INDEPTH results, Science, 1996, 274: 1684–1696.
Ding, Z. F., Zeng, R. S., Wu, F. T., The Pn wave velocities and the relief of Moho in the Tibetan Plateau, Acta Seismologica Sinica, 1993, 6(2): 317–325.
Hearn, T. M., Beghoul, N., Barazangi, M., Tomography of the western United States from regional arrival times, J. Geophys. Res., 1991, 96: 16369–16381.
Hearn, T. M., Anisotropic Pn tomography in the western United States, J. Geophys. Res., 1996, 101: 8403–8414.
Hearn, T. M., Ni, J. F., Pn velocities beneath continental collision zones: The Turkish-Iran Plateau, Geophys. J. Int., 1994, 117:273–283.
Li, S. L., Mooney, W. D., Crustal structure of China from deep seismic sounding profiles, Tectonophysics, 1998, 288: 105–113.
Compilation Group of Achievements in Deep Geophysical Prospecting, State Seismological Bureau, Achievements in Geophysical Prospecting of Crust and Upper Mantle beneath China (in Chinese), Beijing: Seismology Press, 1986.
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Wang, S., Hearn, T., Xu, Z. et al. Velocity structure of uppermost mantle beneath China continent from Pn tomography. Sci. China Ser. D-Earth Sci. 45, 143–150 (2002). https://doi.org/10.1007/BF02879791
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DOI: https://doi.org/10.1007/BF02879791