| Crustal Poisson’s ratio anomalies in the eastern part of North China and their origins |
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| 作者姓名： | Wencai Yang Chen Qu Changqing Yu |
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| 基金项目： | Acknowledgment This research is sponsored by Special National Science and Technology Project on ＂Scientific research of fault zone of Wenchuan Earthquake＂ （the 15th Subject）, and the director fund of Institute of Geology of Chinese Academy of Geological Sciences. Special thanks go to Prof. Shaocheng Ji from Ecole Polytechnique de Montreal for providing vital opinions. The authors are also grateful to Mrs Fengying Zhang for her invaluable help in editing figures. |
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| 摘 要： | Seismic tomography can provide both fine P-wave and S-wave velocity structures of the crust and upper mantle.In addition,with proper computation,Poisson’s ratio images from the seismic velocities can be determined.However,it is unknown whether Poisson’s ratio images have any advantages when compared with the P-wave and S-wave velocity images.For the purposes of this study,high-resolution seismic tomography under the eastern part of North China region was used to determine detailed 3-D crustal P- and S-wave seismic velocities structure,as well as Poisson’s ratio images.Results of Poisson’s ratio imaging show high Poisson’s ratio(high-PR) anomalies located in the Hengshan-North Taihang-Zhangjiakou(H-NT-Z) region,demonstrating that Poisson’s ratio imaging can provide new geophysical constraints for regional tectonic evolution.The H-NT-Z region shows a prominent and continuous high-PR anomaly in the upper crust.Based on Poisson’s ratio images at different depths, we find that this high-PR anomaly is extending down to the middle crust with thickness up to about 26 km.According to rock physical property measurements and other geological data,this crustal Poisson’s ratio anomaly can be explained by Mesozoic partial melting of the upper mantle and basaltic magma underplating related to the lithospheric thinning of the North China craton.
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| 关 键 词： | Seismic tomography North China Craton crust Poisson’s ratio anomaly Magma underplating |
| 收稿时间： | 3/1/2011 12:00:00 AM |
http://www.sciencedirect.com/science/article/pii/S1674987111000557 |
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| Wencai Yang,Chen Qu,Changqing Yu.http://www.sciencedirect.com/science/article/pii/S1674987111000557[J].Geoscience Frontiers,2011,2(3):313-321. |
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| Authors: | Wencai Yang Chen Qu Changqing Yu |
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| Institution: | Key Laboratory of Continental Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China |
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| Abstract: | Seismic tomography can provide both fine P-wave and S-wave velocity structures of the crust and upper mantle. In addition, with proper computation, Poisson’s ratio images from the seismic velocities can be determined. However, it is unknown whether Poisson’s ratio images have any advantages when compared with the P-wave and S-wave velocity images. For the purposes of this study, high-resolution seismic tomography under the eastern part of North China region was used to determine detailed 3-D crustal P- and S-wave seismic velocities structure, as well as Poisson’s ratio images. Results of Poisson’s ratio imaging show high Poisson’s ratio (high-PR) anomalies located in the Hengshan-North Taihang-Zhangjiakou (H-NT-Z) region, demonstrating that Poisson’s ratio imaging can provide new geophysical constraints for regional tectonic evolution. The H-NT-Z region shows a prominent and continuous high-PR anomaly in the upper crust. Based on Poisson’s ratio images at different depths, we find that this high-PR anomaly is extending down to the middle crust with thickness up to about 26 km. According to rock physical property measurements and other geological data, this crustal Poisson’s ratio anomaly can be explained by Mesozoic partial melting of the upper mantle and basaltic magma underplating related to the lithospheric thinning of the North China craton. |
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| Keywords: | Seismic tomography North China Craton crust Poisson’s ratio anomaly Magma underplating |
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