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标题：Seismic structures of the 154–160 Ma oceanic crust and uppermost mantle in the Northwest Pacific Basin
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作者：Mitsuhiro Oikawa ; Kentaro Kaneda ; Azusa Nishizawa 等
期刊名称：Earth, Planets and Space
电子版ISSN：1880-5981
出版年度：2010
卷号：62
期号：4
页码：1-16
DOI：10.5047/eps.2010.02.011
出版社：Springer Verlag
摘要：8 cm/yr and have not been appreciably deformed by tectonic or igneous activity since then.We carried out wide-angle seismic experiments on two crossing survey lines which are respectively parallel and perpendicular to paleomagnetic lineations.The seismic crustal models for both lines are almost identical and homogeneous along these lines.The crust consists of an upper layer (Layer 2) with a P -wave velocity V p = 2.5–6.8 km/s and a thickness of 1.3–2.2 km, and a lower layer (Layer 3) with a velocity of 6.8–7.1 km/s and a thickness of 4.6–5.9 km.These characteristics indicate that the crust beneath the survey line has a standard oceanic crustal structure.The structure of the uppermost mantle of the line parallel to the seafloor spreading direction exhibits considerable V p heterogeneity within 5 km immediately below the Moho and shows an unusually high V p of 8.5–8.7 km/s.The P n velocity for the perpendicular line is 7.9 km/s, and the magnitude of the velocity anisotropy for the uppermost mantle amounts to a large value of 7–10%.
关键词：Oceanic crust ;Northwest Pacific Basin ;seismic structure ;ocean bottom seismograph ;anisotropy