Three-dimensional seismic structure of a Mid-Atlantic Ridge segment characterized by active detachment faulting (Trans-Atlantic Geotraverse, 25 degrees 55 ' N-26 degrees 20 ' N)
文献类型：期刊论文
| 作者 | Zhao, MH ; Canales, JP ; Sohn, RA |
| 刊名 | GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
 |
| 出版日期 | 2012 |
| 卷号 | 13页码:Q0AG13 |
| 关键词 | 3D seismic structure Mid-Atlantic Ridge TAG hydrothermal field active detachment fault |
| ISSN号 | 1525-2027 |
| 通讯作者 | mhzhao@scsio.ac.cn ; jpcanales@whoi.edu ; rsohn@whoi.edu |
| 中文摘要 | We use air gun shots recorded by ocean bottom seismometers (OBSs) to generate a three-dimensional (3D) P-wave tomographic velocity model of the Trans-Atlantic Geotraverse (TAG) segment of the Mid-Atlantic Ridge, and to search for evidence of reflections from a shallow crustal fault interface. Near-vertical reflections were observed in some of the seismic records from OBSs deployed within the active seismicity zone defined by microearthquake hypocenters. Forward modeling of synthetic seismograms indicates that these reflections are consistent with a fault interface dipping at a low angle toward the ridge axis. Our observations suggest that the fault zone may extend beneath the volcanic blocks forming the eastern valley wall. Our 3D tomographic results show that the across-axis structural asymmetry associated with detachment faulting extends at least 15 km to the east of the ridge axis, indicating that detachment faulting and uplifting of deep lithologies has been occurring at the TAG segment for at least the last similar to 1.35 Myr. The velocity model contains a 5 km by 8 km velocity anomaly within the detachment footwall. This anomaly, which is present beneath the active TAG hydrothermal mound, is characterized by a velocity inversion at 1.5-2.0 km below seafloor underlain by reduced P-wave velocities (similar to 6.2-6.5 km/s compared to surrounding areas similar to 7.0-7.2 km/s) extending down to 3.5 km below seafloor. The velocity anomaly likely results from some combination of thermal and/or hydrothermal processes, and in either case our results suggest that hydrothermal fluids circulate within the upper section of the detachment footwall beneath the active mound. |
| 学科主题 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:000310691100002 |
| 公开日期 | 2013-08-28 |
| 源URL | [http://ir.scsio.ac.cn/handle/344004/10297]  |
| 专题 | 南海海洋研究所_中科院边缘海地质重点实验室 |
| 推荐引用方式 GB/T 7714 | Zhao, MH,Canales, JP,Sohn, RA. Three-dimensional seismic structure of a Mid-Atlantic Ridge segment characterized by active detachment faulting (Trans-Atlantic Geotraverse, 25 degrees 55 ' N-26 degrees 20 ' N)[J]. GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,2012,13:Q0AG13. |
| APA | Zhao, MH,Canales, JP,&Sohn, RA.(2012).Three-dimensional seismic structure of a Mid-Atlantic Ridge segment characterized by active detachment faulting (Trans-Atlantic Geotraverse, 25 degrees 55 ' N-26 degrees 20 ' N).GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,13,Q0AG13. |
| MLA | Zhao, MH,et al."Three-dimensional seismic structure of a Mid-Atlantic Ridge segment characterized by active detachment faulting (Trans-Atlantic Geotraverse, 25 degrees 55 ' N-26 degrees 20 ' N)".GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS 13(2012):Q0AG13. |
入库方式： OAI收割
来源：南海海洋研究所
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