Geographic boundary and shear wave velocity structure of the "Pacific anomaly" near the core-mantle boundary beneath western Pacific
文献类型：期刊论文
| 作者 | He, YM; Wen, LX; Zheng, TY |
| 刊名 | EARTH AND PLANETARY SCIENCE LETTERS
 |
| 出版日期 | 2006-04-15 |
| 卷号 | 244期号:1-2页码:302-314 |
| 关键词 | shear wave velocity structure core-mantle boundary Pacific anomaly compositional anomaly African anomaly very-low velocity province |
| ISSN号 | 0012-821X |
| DOI | 10.1016/j.epsl.2006.02.007 |
| 文献子类 | Article |
| 英文摘要 | We determine the geographical boundary and shear-velocity structure of a very-low velocity province at the base of the Earth's mantle beneath western Pacific (we term it the "Pacific anomaly") based on the waveform modeling and travel time analysis of ScSH-SH phases. Our seismic data are from the China National Digital Seismographic Network, the F-net in Japan, the Global Seismographic Network and several PASSCAL arrays. The observed ScS-SH differential travel-time residuals allow the northwestern geographic boundary of the anomaly to be clearly defined. The seismic data also suggest that the average shear-velocity reduction inside the anomaly reaches -5% in the lowermost 300 km of the mantle. Waveform modeling of the seismic data sampling the edge of the anomaly suggests that the northwestern boundary is best characterized by a shear-velocity model with a velocity jump of about 2% at about 100-145 km above the core-mantle boundary and a thin (30-km thick) basal layer with a shear wave velocity reduction of -13%. Stacked seismic data sampling the middle of the anomaly, however, show no evidence for any internal discontinuity with a velocity decrease greater than -2% in the middle of the anomaly. Overall, the seismic data sampling the base of the "Pacific anomaly" can be explained by a negative shear-velocity gradient from 0% to -1% (top) to -13% (bottom) in the lowermost 220 km of the mantle, similar to those of a very-low velocity province beneath the South Atlantic Ocean and the Indian Ocean. Such a strong negative shear-velocity gradient can be explained by partial melting of a compositional anomaly produced early in the Earth's history located within a bottom thermal boundary layer. Our travel time data also exhibit small-scale variations inside the anomaly, indicating existence of internal small-scale seismic heterogeneities inside the "Pacific anomaly". (c) 2006 Elsevier B.V. All rights reserved. |
| WOS关键词 | POST-PEROVSKITE PHASE ; LATERAL VARIATIONS ; SEISMIC EVIDENCE ; EARTHS MANTLE ; INDIAN-OCEAN ; BASE ; LAYER ; D'' ; DISCONTINUITY ; HETEROGENEITY |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:000236991300020 |
| 出版者 | ELSEVIER SCIENCE BV |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/66174]  |
| 专题 | 中国科学院地质与地球物理研究所 |
| 通讯作者 | He, YM |
| 作者单位 | 1.Chinese Acad Sci, Inst Geol & Geophys, Seismol Lab, SKL LE, Beijing 100029, Peoples R China 2.SUNY Stony Brook, Dept Geosci, Stony Brook, NY 11794 USA |
| 推荐引用方式 GB/T 7714 | He, YM,Wen, LX,Zheng, TY. Geographic boundary and shear wave velocity structure of the "Pacific anomaly" near the core-mantle boundary beneath western Pacific[J]. EARTH AND PLANETARY SCIENCE LETTERS,2006,244(1-2):302-314. |
| APA | He, YM,Wen, LX,&Zheng, TY.(2006).Geographic boundary and shear wave velocity structure of the "Pacific anomaly" near the core-mantle boundary beneath western Pacific.EARTH AND PLANETARY SCIENCE LETTERS,244(1-2),302-314. |
| MLA | He, YM,et al."Geographic boundary and shear wave velocity structure of the "Pacific anomaly" near the core-mantle boundary beneath western Pacific".EARTH AND PLANETARY SCIENCE LETTERS 244.1-2(2006):302-314. |
入库方式： OAI收割
来源：地质与地球物理研究所
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