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学科主题: Geochemistry & Geophysics
题名: 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)
作者: Zhao, MH ; Canales, JP ; Sohn, RA
通讯作者: mhzhao@scsio.ac.cn ; jpcanales@whoi.edu ; rsohn@whoi.edu
关键词: 3D seismic structure ; Mid-Atlantic Ridge ; TAG hydrothermal field ; active detachment fault
刊名: GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
发表日期: 2012
卷: 13, 页:Q0AG13
部门归属: [Zhao, Minghui] Chinese Acad Sci, S China Sea Inst Oceanol, Key Lab Marginal Sea Geol, Guangzhou 510301, Guangdong, Peoples R China; [Canales, Juan Pablo; Sohn, Robert A.] Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA
项目归属: 海洋地质
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.
语种: 英语
WOS记录号: WOS:000310691100002
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内容类型: 期刊论文
URI标识: http://ir.scsio.ac.cn/handle/344004/10297
Appears in Collections:中科院边缘海地质重点实验室_期刊论文

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Recommended Citation:
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),GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,2012,13():Q0AG13
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