| 中国东北地区高精度相速度层析成像及其构造意义 |
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| 引用本文： | 田原,C. P. Legendre,周彤,韩建刚,吴梦羽,赵里,宁杰远.中国东北地区高精度相速度层析成像及其构造意义[J].地球物理学报,2017,60(5):1659-1675. |
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| 作者姓名： | 田原 C. P. Legendre 周彤 韩建刚 吴梦羽 赵里 宁杰远 |
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| 作者单位： | 1. 北京大学固体地球物理系, 北京 100871;2. 中国地震局地球物理研究所, 北京 100081;3. 台湾"中央研究院"地球科学研究所, 台北 11529;4. 台湾大学地球科学系, 台北 10617;5. 美国华盛顿大学地球科学系, 西雅图 98466 |
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| 基金项目： | 地震行业专项（201408013）和国家自然科学基金（41130316）资助. |
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| 摘 要： | 本文利用均匀布设于中国东北地区的48个中国国家地震台网固定台站所收集的5年期宽频带远震数据,利用双台法手动挑选出68642条高质量的面波频散曲线,并合成为1088条纯路径平均频散曲线.结合东北地区的密集流动台阵得到的背景噪声相速度频散曲线,本文反演得到了东北地区瑞利波各向同性相速度及方位角各向异性图像.长时间搜集并经过严格筛选的相速度频散数据有效地提升了结果的分辨率.短周期各向同性相速度结果主要受控于浅部结构,各大盆地均明显地表现为相对低速,而山区则为相对高速.40 s左右的相速度图像显示松辽盆地西北角有明显的高速.60 s以上图像中,松辽盆地分为较为明显的南北两部分:北部各向同性相速度值略低,且有明显的北西—南东向方位角各向异性;南部各向同性相速度值偏高,且方位各向异性不明显,可能说明盆地北部100 km以下存在速度较低、流动性较强的地幔,而南部该深度范围似乎对应高速、流动性较弱的地幔.结果似乎表明,松辽盆地西北角可能仍然存在不太厚的完整的岩石圈,但其他区域均已遭到不同程度的破坏.区域内各大火山区在相速度图像中均显示为相对低速,长白山下方在短周期到长周期图像中均显示为较强的低速;五大连池火山群从25s到60s存在较明显低速;大兴安岭—带哈拉哈和阿巴嘎火山群的低速可延伸至120 s.同时,五大连池、哈拉哈和阿巴嘎火山在60~100 s的范围内的低速"根"通过松辽盆地下方各向异性为北西—南东向的低速结构与东部长白山火山的低速"根"相连,显示区域内的新生代火山活动很可能与长白山下方热物质的上涌有关.
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| 关 键 词： | 中国东北 相速度 各向异性 岩石圈 软流圈 |
| 收稿时间： | 2016-05-12 |
High resolution anisotropic phase velocity tomography of Northeast China and its implication |
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| TIAN Yuan,C.P. Legendre,ZHOU Tong,HAN Jian-Gang,WU Meng-Yu,ZHAO Li,NING Jie-Yuan.High resolution anisotropic phase velocity tomography of Northeast China and its implication[J].Chinese Journal of Geophysics,2017,60(5):1659-1675. |
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| Authors: | TIAN Yuan CP Legendre ZHOU Tong HAN Jian-Gang WU Meng-Yu ZHAO Li NING Jie-Yuan |
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| Institution: | 1. Institute of Theoretical and Applied Geophysics, Peking University, Beijing 100871, China;2. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China;3. Institute of Earth Sciences, Academia Sinica, Taipei 11529, China;4. Department of Gepsciences, "National Taiwan University", Taipei 10617, China;5. Department of Geosciences, University of Washington, Seattle 98466, USA |
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| Abstract: | We build isotropic and azimuthally anisotropic Rayleigh-wave phase velocity maps of Northeast China (NEC) from teleseismic and ambient noise data. Dispersion curves of 68642 vertical component seismograms from 5-year teleseismic data recorded by 48 evenly distributed CEA permanent stations are extracted using two-station method, then manually selected and averaged to obtain a total of 1088 inter-station pure path averaged dispersion curves. 2-year ambient noise data with strict quality control is used as a supplement to the teleseismic dispersion curves at short periods. Long time recorded and strictly selected phase velocity dispersion curves effectively improve the resolution of tomography. Isotropic phase velocity maps are in good accordance with the surface geology, showing relatively low velocity in basins and high velocity in mountainous regions. Around 40 s, a high velocity anomaly is shown in the northwest corner of Songliao basin. In phase velocity maps of 60 s and longer periods, distinct features are shown in north and south Songliao basin. The north Songliao basin shows relatively low isotropic phase velocity but obvious azimuthal anisotropy with fast direction pointing NW-SE. Contrarily, the south Songliao basin shows high isotropic phase velocity without obvious azimuthal anisotropy. This implies that there is low-velocity mantle beneath north Songliao basin around 100 km, but high-velocity mantle beneath south Songliao basin at similar depth range. All volcanic zones in our study region shows relatively low velocity anomaly in phase velocity maps. Phase velocity of Changbaishan volcano shows strong low velocity anomaly in nearly all periods. Wudalianchi volcano shows obvious low velocity anomaly from 25 s to 60 s in periods. The low velocity anomaly of Halaha and Abaga volcano could extend to 120 s. Meanwhile, between 60 s and 100 s, the low velocity zones beneath Wudalianchi, Halaha and Abaga volcano link with the low velocity zone below Changbaishan volcanos through a low velocity zone beneath Songliao basin, which shows NW-SE azimuthal anisotropy pointing to Changbaishan volcano, indicating that the Cenozoic volcanism of the whole region might be influenced by the hot mantle upwelling below Changbaishan volcano. |
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| Keywords: | Northeast China Phase velocity Azimuthal anisotropy Lithosphere Asthenosphere |
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