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1 School of Earth and Environmental
Sciences
Seoul National University
Seoul 151-747, South
Korea
joshua{at}snu.ac.kr
baagce{at}snu.ac.kr
* Present address: Department of Earth and Planetary Sciences, Northwestern University, Evanston, Illinois 60208.
We estimated Moho depths and VP/VS
ratios of the crust under 21 broadband
stations in southern Korea by using a grid search in the crustal
thickness–VP/VS ratio
(H-
) domain. The Moho depth varies from 25.9 km to 32.5 km, and
the
VP/VS ratio ranges from 1.71 to 1.82
inland. Moho depths in the southernmost area
of the Korean Peninsula were estimated shallower than those of the previous
results
obtained assuming a Poisson solid in the joint analysis of receiver functions
and
surface-wave dispersion. This southernmost area is roughly in accord with the
Yeongnam massif, where relatively high
VP/VS ratios of 1.78–1.82 are
estimated. On
the contrary, comparatively low VP/VS
ratio measurements (1.71–1.76) are generally
distributed in the Gyeonggi massif, which is located in the central area of the
Korean
Peninsula. The major factor for the high
VP/VS ratios in the Yeongnam massif is
thought to be the plagioclase-rich mafic composition of the lower crust rather
than
partial melting or crustal fluids, because high crustal S-wave
velocities are reported
in the Yeongnam massif. The mafic composition might have been supplied by the
magmatic underplating. From the clearly divided feature of
VP/VS ratios in southern
Korea and the VP/VS ratio similarities
between southern Korea and China, it seems
that the Yeongnam massif might be related to the Sino-Korea craton, whereas the
Gyeonggi massif is related to the Yangtze craton.
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