HR: 1340h
AN: T13B-1336    [Abstracts]
TI: Observation of the Type-B Crystallographic Preferred Orientation of Olivine in Spinel Peridotite, Baengnyeong Island, South Korea
AU: * Jung, H
EM: hjung@snu.ac.kr
AF: School of Earth and Environmental Sciences, Seoul National University, Seoul, 151-747, Korea, Republic of
AU: Mo, W
EM: wonimo@snu.ac.kr
AF: School of Earth and Environmental Sciences, Seoul National University, Seoul, 151-747, Korea, Republic of
AU: Ree, J
EM: reejh@korea.ac.kr
AF: Department of Earth and Environmental Sciences, Korea University, Seoul, 136-701, Korea, Republic of
AU: Kim, J
EM: mdew2000@korea.ac.kr
AF: Department of Earth and Environmental Sciences, Korea University, Seoul, 136-701, Korea, Republic of
AB: Crystallographic preferred orientation (CPO)s of olivine and clinopyroxene in spinel peridotite from Baengnyeong Island in South Korea were investigated. Baengnyeong Island is located in the western most part of Korea in Yellow Sea and near the boundary between the Phanerozoic Imjingang belt and Precambrian Nangrim massif in North Korea. The Imjingang belt has been considered to be an eastern extension of the Quiling-Dabie-Sulu collision belt (Ree et al., 1996). The sample spinel peridotite was collected from the Pliocene basalt in Baengnyeong Island. To determine CPOs of olivine and clinopyroxene, we used electron backscattered diffraction (EBSD) and HKL Channel software. We found that olivine [001] axis is subparallel to the lineation and olivine [010] axis normal to the foliation plane, suggesting deformation of olivine by the (010)[001] slip system (olivine type-B fabric). The olivine type-B fabric is of particular interest because it may be used to explain the trench-parallel shear-wave splitting that is often observed at subduction zones. CPO of clinopyroxene showed that [001] axis is subparallel to the lineation and [100] axis normal to the foliation plane, suggesting deformation of clinopyroxene by the (100)[001] slip system. The type-B CPO of olivine was observed experimentally at the conditions of high stress and/or under moderate to high water content (Jung et al, 2006). The sample spinel peridotite is considered to have been deformed at high stress condition, suggesting that upper mantle under Baengnyeong Island had experienced high stress in the past and the Quiling-Dabie-Sulu collision belt was probably extended to the area close to the Baengnyeong Island in South Korea.
DE: 3902 Creep and deformation
DE: 5112 Microstructure
DE: 5120 Plasticity, diffusion, and creep
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting