Two-station measurement of Rayleigh-wave phase velocities for the Huatung basin, the westernmost Philippine Sea, with OBS: implications for regional tectonics

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Title:	Two-station measurement of Rayleigh-wave phase velocities for the Huatung basin, the westernmost Philippine Sea, with OBS: implications for regional tectonics
Authors:	Kuo,BY;Chi,WC;Lin,CR;Chang,ETY;Collins,J;Liu,CS
Contributors:	地球物理研究所
Keywords:	UPPER-MANTLE BENEATH;MARGINAL BASINS;PARECE VELA;LUZON ARC;PLATE;TAIWAN;SUBDUCTION;PACIFIC;LITHOSPHERE;TOMOGRAPHY
Date:	2009
Issue Date:	2010-06-29 18:41:10 (UTC+8)
Publisher:	中央大學
Abstract:	A broad-band ocean-bottom seismometer (OBS) deployed similar to 180 km east of Taiwan provides a first glimpse into the upper mantle beneath the westernmost section of the Philippine Sea or the Huatung basin (HB). We measured interstation phase velocities of Rayleigh waves between the OBS and stations on the eastern coast of Taiwan. The phase velocities show smooth variations from 3.8 to 3.9 km s(-1) for periods of 25-40 s. In this short period range, phase velocities are comparable to those characterizing the 15-30 Ma Parece-Vela basin of the Philippine Sea. Modelling of the finite-frequency effect proves the validity of the measurement for the average HB. The shear-wave velocity models inverted from the 25 to 40 s dispersion show a velocity at lithospheric depths about 0.1 km s(-1) lower than that of the west Philippine Sea, which agrees with the age effect derived from the Pacific pure-path model. Inversions incorporating the less reliable data above 40 s yield a shear velocity < 4.0 km s(-1) below 150 km, an unrealistic value even for a hotspot plume environment. The seismological evidence, together with the correlation in seafloor depth, suggests that the HB and the Parece-Vela basin may have a similar age. This is at odds with the previous geochronological study suggesting an early-Cretaceous age for the HB. Thermal rejuvenation of the lithosphere was examined as a potential solution to reconciling the two age models.
Relation:	GEOPHYSICAL JOURNAL INTERNATIONAL
Appears in Collections:	[Graduate Institute of Geophysics] journal & Dissertation

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