Seismic anisotropy of upper mantle beneath the Dabie-Sulu and its adjacent areas
Seismic anisotropy of upper mantle beneath the Dabie-Sulu and its adjacent areas
复制标题
大别-苏鲁及其邻区上地幔地震各向异性
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
Li Zhen
中科院分区：
文献类型：
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作者：
Wang Chun-Yong;Ding Zhi-Feng;Chang Li-Jun;Li Zhen
大别-苏鲁造山带是扬子陆块与华北陆块的碰撞带，对该区上地幔各向异性的研究有助于我们认识地幔动力学过程。河南、湖北数字地震台网和中国宽带数字地震台网（2006.05~2011.05）.利用旋转相关和横向分量最小化方法，我们得到了分裂参数（Φ，结果表明，研究区的快、慢波延迟时间在0.5 ~ 1.63 s之间，表明各向异性构造的深度约为57.5~187.45 km，本文将华北地区的快波极化方向分为四组，华北地区的快波极化方向与华北地区的快波极化方向基本一致，华北地区的快波极化方向与华北地区的快波极化方向基本一致，华北地区的快波极化方向与华北地区的快波极化方向基本一致，华北地区的快波极化方向与华北地区的快波极化方向基本一致大别造山带上地幔各向异性结果与造山带走向有较好的对应关系，反映了扬子地块与华北地块的南北向挤压碰撞作用。大别山南部的各向异性与大别造山带基本垂直，大别山东部的各向异性为NEE-SWW向，苏鲁造山带的各向异性为NEE-SWW向，上地幔各向异性可以用软流圈对流和所谓的“化石各向异性”的综合作用来解释。在印支-燕山期岩石圈冻结。
The Dabie-Sulu orogenic belt is a collision zone of the Yangtze block and North China block,and the analysis on upper-mantle anisotropy beneath the study region will help us to understand the mantle dynamics process.In this paper,we have analyzed observations of low frequency SKS waves recorded by Shandong,Jiangsu,Anhui,Henan and Hubei digital seismograph networks and China Broadband Digital Seismograph Network(2006.05~2011.05).With rotation correlation and transverse component minimization methods,we have obtained splitting parameters(Φ,δt) beneath Dabie-Sulu and its adjacent areas.The results show that the delay times between fast and slow wave range from 0.5 s to 1.63 s in the study,which indicate that the anisotropic structures are at depths about 57.5~187.45 km,including the effects of lithosphere and asthenosphere.The fast wave polarization directions beneath this area are divided into four groups.The fast wave polarizations beneath North China are nearly E-W,and according to the geology,we infer that the upper mantle anisotropy beneath North China is caused by the convection of the asthenosphere.The anisotropy results beneath Dabie orogenic belt show a good relation with the strike direction of the belt,which reflect the north-south-trending compression and collision of Yangtze block and North China block.In Yangtze,the results to the south of Dabie are nearly perpendicular to the Dabie orogenic belt,and the results to the east of Dabie show NEE-SWW trends.The anisotropy beneath Sulu orogenic belt is NEE-SWW,which are different from both the strike direction of the surface structures and the absolute plate motion.The upper mantle anisotropy can be explained by the combined effects of asthenosphere convection and the so-called "fossil anisotropy" frozen in the lithosphere during the Indosinian-Yanshanian period.