HR: 0830h
AN: T31D-0863    [PDF]
TI: Evidence for Rifting Above Hotter Than Normal Mantle : Deep Seismic Sounding at the Continental Margin of Korea in the East Sea (Japan Sea)
AU: * Jou, H
EM: htjou@kordi.re.kr
AF: Korea Ocean R & D Institute, Ansan P.O. Box 29, Ansan, 425-600 Korea, Republic of
AU: Kim, H
EM: hanjkim@kordi.re.kr
AF: Korea Ocean R & D Institute, Ansan P.O. Box 29, Ansan, 425-600 Korea, Republic of
AU: Cho, H
AF: School of Earth & Env. Sci., Seoul Nat'l Univ., San 56-1, Shillim-Dong, Seoul, 151-742 Korea, Republic of
AU: Bijwaard, H
AF: Nat'l Inst. for Public Health & Env., P.O. Box 1, Bilthoven, 3270 Netherlands
AB: The continental margin of the Korean Peninsula is little known in its crustal structure, although various opening models of the southwestern part of the East Sea (Japan Sea) have been presented. Accordingly, continental rifting and subsequent seafloor spreading processes in the East Sea have not been adequately addressed. The crustal and sedimentary velocity structures were investigated across the Korean margin into the adjacent Ulleung Basin from multi-channel seismic reflection and ocean bottom seismometer data. The Ulleung Basin shows crustal velocity structure typical of oceanic although its crustal thickness of about 10 km is greater than normal. The continental margin featuring rapid transition from continental to oceanic crust exhibits a remarkable decrease in crustal thickness accompanied by shallowing of Moho over a distance of about 50 km. The crustal model of the margin is characterized by a high-velocity lower crustal (HVLC) layer that is thicker than 10 km under the slope base and pinches out seawards. The HVLC layer is interpreted as magmatic underplating emplaced during continental rifting in response to high upper mantle temperature. The acoustic basement of the slope base shows an igneous stratigraphy developed by massive volcanic eruption. These features suggest that the evolution of the Korean margin can be explained by the processes occurring at volcanic rifted margins above the hot upper mantle, which is supported by global earthquake tomography and magnetic observations across the Korean margin.
DE: 7220 Oceanic crust
DE: 8105 Continental margins and sedimentary basins
SC: Tectonophysics [T]
MN: 2003 Fall Meeting