HR: 0800h
AN: T11A-1245 [Abstracts]
TI: Multidisciplinary Surveys for the Crustal Structure of the Ltzow-Holm Complex, Enderby Land, East
Antarctica: SEAL-2000, -2002
AU: * Toda, S
EM: shigeru@auecc.aichi-edu.ac.jp
AF: Aichi University of Education, Hirosawa 1, Igaya, Kariya, AIC 448-8542
Japan
AU: Miyamachi, H
EM: miya@sci.kagoshima-u.ac.jp
AF: Kagoshima University, Kagoshima, Kagoshima, KGS 890-0065
Japan
AU: Kanao, M
EM: kanao@nipr.ac.jp
AF: National Institute of Polar Research, 1-9-10 Kaga, Itabashi, TKY 173-8515
Japan
AU: Murakami, H
EM: mrkm@bosai.go.jp
AF: Earthquake Observation Research Technology Center, Tennoudai 3-1, Tsukuba, IBR 305-0006
Japan
AU: Tsutsui, T
EM: tom@buttan.mine.akita-u.ac.jp
AF: Akita University, Tegata Gakuen-cho 1-1, Akita, AKT 010-8502
Japan
AU: Matsushima, T
EM: mat@sevo.kyushu-u.ac.jp
AF: Kyushu University, 2-5643-29 Shin'yama, Shimabara, NGS 855-0843
Japan
AU: Takada, M
EM: takada@eos.hokudai.ac.jp
AF: Hokkaido University, Nishi 8, Kita 10, Kita-Ku, Sapporo, HKD 060-0810
Japan
AU: Yamashita, M
EM: yama@nipr.ac.jp
AF: National Institute of Polar Research, 1-9-10 Kaga, Itabashi, TKY 173-8515
Japan
AU: Watanabe, A
EM: watanabe@sevo.kyushu-u.ac.jp
AF: Kyushu University, 2-5643-29 Shin'yama, Shimabara, NGS 855-0843
Japan
AU: Fukuda, Y
EM: fukuda@kugi.kyoto-u.ac.jp
AF: Kyoto University, Kitashirakawa-Oiwake-cho, Sakyou-ku, Kyoto, KYT 606-8502
Japan
AB:
Lithospheric evolution of the East Antarctic shield is one of the keystones for understanding continental growth process
during the Earth's evolution. Architecture of the East Antarctic craton and the surrounding areas would be characterized by
a comparison with lithospheric structure of the other Precambrian terrains by deep seismic surveys. A geoscience program
named "Structure and Evolution of the East Antarctic Lithosphere (SEAL)" is carrying out since 1997 austral summer as part of
the Japanese Antarctic Research Expedition (JARE). Several geological and geophysical surveys were conducted including a
deep seismic refraction / wide-angle reflection and gravimetric surveys in the Ltzow-Holm Complex (LHC), Western Enderby
Land, East Antarctica. The LHC had been experienced a high-grade metamorphism during the Pan-African orogenic event, where
is considered to be the collision zones in the last stage of the formation of Gondwana.
In the austral summer in 2000, and 2002, two big seismic surveys were carried out on the continental ice sheet of the Mizuho
Plateau in the LHC by SEAL program. In both surveys, more than 170 geophones were installed on the plateau totally 190 km in
length. A total of 8,300 kg dynamite charges at the fourteen seismic shot points on the ice sheet gave enough information
concerning the deep structure of a continental margin of the LHC. The gravity measurements were conducted by a SCINTREX
(CG-3M) gravity meter at about 1 km-interval along the seismic survey lines. These surveys had revealed that the Moho depth
was more than 40 km with the velocities of the surface layer, the middle crust, the lower crust and the mantle, about 6.2,
6.4, 6.7 and 7.9 km/s. Moreover, the clear reflected waves from the lower crust and the Moho were observed on all the record
sections. In this presentation, we review the subsurface structure of the LHC by several geophysical approaches, such as
the seismic first arrival and wide-angle analyses, gravity measurements, GPS positioning and also the radio-echo soundings to
detect the precise bedrock elevation around the seismic traverse routes. Then the multidisciplinary crustal model of the
LHC will be presented including geological evidence to estimate the evolution process around the coastal outcrops.
DE: 0900 EXPLORATION GEOPHYSICS
DE: 0920 Gravity methods
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting