Seismic anisotropy of upper mantle in eastern Tibetan Plateau and related crust-mantle coupling pattern |
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基金项目: | Supported by the
Continental Dynamics Program of the National Natural Science Foundation of China (Grant
No. 40334041) and the International Cooperation Program of the Ministry of Science and
Technology of China (Grant No.2003DF000011) |
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摘 要: | By using the polarization analysis of teleseismic SKS waveform data recorded at 116 seismic stations which respectively involved in China National Digital Seismograph Network, and Yunnan, Sichuan, Gansu and Qinghai regional digital networks, and portable broadband seismic networks deployed in Sichuan, Yunnan and Tibet, we obtained the SKS fast-wave direction and the delay time between fast and slow waves of each station by use of the stacking analysis method, and finally acquired the fine image of upper mantle anisotropy in the eastern Tibetan Plateau and its adjacent regions. We analyzed the crust-mantle coupling deformation on the basis of combining the GPS observation results and the upper mantle anisotropy distribution in the study area. The Yunnan region out of the plateau has dif-ferent features of crust-mantle deformation from the inside plateau. There exists a lateral transitional zone of crust-mantle coupling in the eastern edge of the Tibetan Plateau, which is located in the region between 26° and 27°N in the west of Sichuan and Yunnan. To the south of transitional zone, the fast-wave direction is gradually turned from S60°―70°E in southwestern Yunnan to near EW in south-eastern Yunnan. To the north of transitional zone in northwestern Yunnan and the south of western Sichuan, the fast-wave direction is nearly NS. From crust to upper mantle, the geophysical parameters (e.g. the crustal thickness, the Bouguer gravity anomaly, and tectonic stress direction) show the feature of lateral variation in the transitional zone, although the fault trend on the ground surface is inconsis-tent with the fast-wave direction. This transitional zone is close by the eastern Himalayan syntaxis, and it may play an important role in the plate boundary dynamics.
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收稿时间: | 30 June 2006 |
修稿时间: | 21 December 2006 |
Seismic anisotropy of upper mantle in eastern Tibetan Plateau and related crust-mantle coupling pattern |
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Authors: | Wang ChunYong Chang LiJun Lü ZhiYong Qin JiaZheng Su Wei Paul Silver Lucy Flesch |
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Institution: | 1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 2. Sichuan Earthquake Administration, Chengdu 610041, China 3. Yunnan Earthquake Administration, Kunming 650041, China 4. Carnegie Institution of Washington, Washington DC 200015, USA |
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Abstract: | By using the polarization analysis of teleseismic SKS waveform data recorded at 116 seismic stations which respectively involved
in China National Digital Seismograph Network, and Yunnan, Sichuan, Gansu and Qinghai regional digital networks, and portable
broadband seismic networks deployed in Sichuan, Yunnan and Tibet, we obtained the SKS fast-wave direction and the delay time
between fast and slow waves of each station by use of the stacking analysis method, and finally acquired the fine image of
upper mantle anisotropy in the eastern Tibetan Plateau and its adjacent regions. We analyzed the crust-mantle coupling deformation
on the basis of combining the GPS observation results and the upper mantle anisotropy distribution in the study area. The
Yunnan region out of the plateau has different features of crust-mantle deformation from the inside plateau. There exists
a lateral transitional zone of crust-mantle coupling in the eastern edge of the Tibetan Plateau, which is located in the region
between 26° and 27°N in the west of Sichuan and Yunnan. To the south of transitional zone, the fast-wave direction is gradually
turned from S60°–70°E in southwestern Yunnan to near EW in south-eastern Yunnan. To the north of transitional zone in northwestern
Yunnan and the south of western Sichuan, the fast-wave direction is nearly NS. From crust to upper mantle, the geophysical
parameters (e.g. the crustal thickness, the Bouguer gravity anomaly, and tectonic stress direction) show the feature of lateral
variation in the transitional zone, although the fault trend on the ground surface is inconsistent with the fast-wave direction.
This transitional zone is close by the eastern Himalayan syntaxis, and it may play an important role in the plate boundary
dynamics.
Supported by the Continental Dynamics Program of the National Natural Science Foundation of China (Grant No. 40334041) and
the International Cooperation Program of the Ministry of Science and Technology of China (Grant No. 2003DF000011) |
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Keywords: | upper mantle anisotropy SKS wave fast-wave direction crust-mantle coupling lithospheric deformation |
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