A study on Dokdo and surrounding seamounts in the northeastern part of the Ulleung Basin of the East Sea using geophysical data: Implications for loading history of their seamounts

Title
A study on Dokdo and surrounding seamounts in the northeastern part of the Ulleung Basin of the East Sea using geophysical data: Implications for loading history of their seamounts
Author(s)
김창환; 박찬홍; 정의영; Yu, S; 곽준영
KIOST Author(s)
Kim, Chang Hwan(김창환)Park, Chan Hong(박찬홍)Jeong, Eui Young(정의영)
Alternative Author(s)
김창환; 박찬홍; 정의영
Publication Year
2006-12-01
Abstract
The northeastern part of the Ulleung Basin in the East Sea (the Sea of Japan) is characterized by complicated morphology consisting of volcanic islands (Ulleungdo and Dokdo), seamounts (the Anyongbok Seamount, the Simheungtaek and the Isabu Tablemounts), and a deep pathway (Korea Gap). The crustal and flexural models and VGP (virtual geomagnetic pole) were computed for this area from gravity and magnetic anomalies. 2-D gravity modeling and inversion show that the depth of Moho is shallow in the Korea Gap and increases toward the Oki Bank and the northwestern part of Ulleungdo. It is similar to the trend of bouguer gravity anomalies of the study area. In spite of their similarity in topographic expression, a large difference about 50 mGal in gravity anomaly peaks between Dokdo and the Isabu Tablemount suggests a different isostatic compensation degree. The flexural model well predicts the observed gravity data. Modeling results for the Dokdo seamounts imply that the age of lithosphere at the time of loading for the Dokdo seamounts was young. Also, they show that the flexural rigidity (or elastic thickness) of the lithosphere of Dokdo is stronger (or thicker) than the Isabu Tablemount. Consequently, the age of lithosphere of the Isabu Tablemount at the time of loading might be less than that of Dokdo. Different magnetic anomaly patterns recognized for Dokdo and adjacent seamounts (the Isabu and the Simheungtaek Tablemounts) possibly imply that they were formed at the different times or composed of different structure. VGP for Dokdo indicates that there was a first large eruption during a normal polarity interval in which the lavas formed the base of Dokdo. Then the second large eruption during a reversed polarity interval formed the crest of Dokdo. From previous stuies of rock samples, the subaerial portion of Dokdo was dated from 4.6 ± 0.4 Ma, early Pliocene to 2.7 ± 0.1 Ma, late Pliocene and the age of Ulleungdo was estimated from 2.7 ± 0.9 Ma, Pliocene to 1.8 ±
URI
https://sciwatch.kiost.ac.kr/handle/2020.kiost/30702
Bibliographic Citation
2006 AGU Fall Meeting, pp.1, 2006
Publisher
American Geophysical Union
Type
Conference
Language
English
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