| 中国东北地区SKS分裂的上地幔各向异性结构与动力学 |
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| 引用本文： | 鲁明文,雷建设,张贵宾.中国东北地区SKS分裂的上地幔各向异性结构与动力学[J].地球物理学报,2019,62(9):3365-3384. |
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| 作者姓名： | 鲁明文 雷建设 张贵宾 |
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| 作者单位： | 1. 中国地震局地壳应力研究所(地壳动力学重点实验室), 北京 100085;2. 中国地质大学(北京)地球物理与信息技术学院, 北京 100083 |
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| 基金项目： | 中国地震局地壳应力研究所基本科研业务专项（ZDJ2017-02）、国家自然科学基金重点项目（41530212）、国家自然科学基金面上项目（41674091）、中国科学院战略性先导科技专项（B类）（XDB18000000）和科技部国家重点研发计划（2016YFC0600408）资助. |
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| 摘 要： | 本研究收集了中国东北地区2008—2016年九年时间内207个固定地震台站和127个NECESSArray流动地震台站的波形资料，利用SKS波分裂的最小切向能量网格搜索方法获得了243个台站的有效分裂结果.研究结果显示，尽管研究区各向异性快波方向基本以NW-SE向为主，但无论是在快波方向上还是快慢波时间延迟上不同构造单元内部与不同构造单元之间均存在着较大差别.大兴安岭造山带北部的各向异性快波方向自北向南由NNE-SSW向转变为NNW-SSE向，在中部以NW-SE向为主，而南部自北而南由NE-SW向逐渐转变为近E-W向；松辽盆地的各向异性快波方向在北部自西向东主要表现为由NNW-SSE向逐渐转变为NW-SE向，在中部自西向东由NE-SW向转变为近E-W向，而在南部既有NE-SW向又有NW-SE向；佳木斯地块各向异性方向由西部的NW-SE转变为东部的NNW-SSE，同时快慢波时间延迟逐渐变大；长白山造山带北部自北向南由NW-SE向逐渐转变为近E-W向，中部各向异性快波方向为NNW-SSE向，且快慢波时间延迟较大，而南部以NW-SE向为主；燕山造山带的各向异性快波方向主要沿E-W向分布，基本平行于燕山造山带的走向.这些结果说明，尽管复杂的各向异性快波方向与局部岩石圈拆沉和热物质上涌有关，但更重要是与"大地幔楔"中物质水平流等动力过程密切相关，也有待将来结合更多地震资料如面波不同深度的特征各向异性进行分析.在阿巴嘎火山群、哈拉哈火山群、长白山火山、龙岗火山和镜泊湖火山区及五大连池火山区等特殊构造区的周边地区，各向异性快波方向围绕这些构造区随方位均发生明显变化，暗示了火山区下方热物质上涌可能影响了"大地幔楔"中的软流圈物质水平流方向.
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| 关 键 词： | SKS波分裂 地震各向异性 深部动力学 东北地区 |
| 收稿时间： | 2018-11-11 |
Upper-mantle seismic anisotropy structure and dynamics beneath NE China inferred from SKS splitting analysis |
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| LU MingWen,LEI JianShe,ZHANG GuiBin.Upper-mantle seismic anisotropy structure and dynamics beneath NE China inferred from SKS splitting analysis[J].Chinese Journal of Geophysics,2019,62(9):3365-3384. |
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| Authors: | LU MingWen LEI JianShe ZHANG GuiBin |
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| Institution: | 1. Key Laboratory of Crustal Dynamics, Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085, China;2. School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China |
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| Abstract: | In this study, we collect the waveform data recorded at the 207 permanent seismic stations from 2008 to 2016 and 127 Northeast China Extended Seismic Array (NECESSArray) temporary seismic stations in Northeast China. Using the minimum transverse energy grid search method of SKS wave splitting, the effective splitting results at 243 stations are obtained. Our results show that the fast direction of anisotropy is dominated by the NW-SE direction, but there are obvious contrasts within the tectonic units and between different units. In the northern part of the Great Xing'an range, the fast direction of anisotropy changes from NNE-SSW in the north to NNW-SSE in the south, and in the middle it is dominated by the NW-SE direction, whereas in the south it changes from NE-SW in the north to nearly E-W in the south. In the Songliao basin, in the northern part, the fast direction of anisotropy changes mainly from NNW-SSE in the west to NW-SE in the east, in the middle part it changes from NE-SW in the west to nearly E-W in the east, whereas in the southern part it mixes NE-SW with NW-SE. The Jiamusi block shows the fast direction changes from NW-SE in the west to NNW-SSE in the east, and the fast-slow-wave delay time gradually becomes larger. The northern Changbaishan orogenic belt illustrates a fast-direction transition from NW-SE in the north to nearly E-W in the south, the middle belt demonstrates a fast direction of NNW-SSE, whereas the southern belt shows a NW-SE direction. In the Yanshanian orogenic belt, the fast direction of anisotropy is mainly along the E-W direction, generally parallel to the strike of the belt. These results indicate that although the complicated pattern of fast directions is somewhat related to the delamination of lithospheric materials and upwelling of hot asthenospheric materials, it is more associated with the horizontal flow of the big mantle wedge due to the deep subduction of the western Pacific slab. In the margins of the Abaga and Halaha volcanic groups, the Changbaishan, Longgang, and Jingpohu volcanic areas, and the Wudalianchi volcano, the fast direction of anisotropy changes obviously, suggesting that the upwelling of hot materials could affect the horizontal flow direction of the big mantle wedge. |
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| Keywords: | SKS wave splitting Seismic anisotropy Mantle dynamics NE China |
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