HR: 0800h
AN: T11C-0395    [Abstracts]
TI: Stratigraphic and Structural Development of the Ontong Java Plateau
AU: * Inoue, H
EM: inoue@ori.u-tokyo.ac.jp
AF: Ocean Research Institute, University of Tokyo, 1-15-1 Minami-dai, Nakano-ku, Tokyo, 164-8639 Japan
AU: Coffin, M F
EM: mcoffin@ori.u-tokyo.ac.jp
AF: Ocean Research Institute, University of Tokyo, 1-15-1 Minami-dai, Nakano-ku, Tokyo, 164-8639 Japan
AU: Nakamura, Y
EM: saru@ori.u-tokyo.ac.jp
AF: Ocean Research Institute, University of Tokyo, 1-15-1 Minami-dai, Nakano-ku, Tokyo, 164-8639 Japan
AU: Mochizuki, K
EM: kimi@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-8654 Japan
AU: Kroenke, L W
EM: kroenke@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, 1680 East West Road, Honolulu, 96822-2327 United States
AB: The Ontong Java Plateau (OJP) in the western equatorial Pacific is Earth's most voluminous large igneous province (LIP). It encompasses an area of approximately 2.0×10⁶ km², and its maximum crustal thickness exceeds 30 km. Emplacement of the OJP at approximately 122 Ma represents a significant transfer of mass and energy from the mantle to the crust. We completed the first east-west and north-south multichannel seismic reflection (MCS) transects of the OJP during R/V Hakuho Maru cruise KH98-01 Leg 2 (February 1998) and R/V Kairei cruise KR05-01 (January 2005). On the basis of new and existing MCS data, single channel seismic (SCS) reflection data, DSDP/ODP results, and other geophysical data, we address the stratigraphic and structural development of the OJP. Specifically, our geophysical work focuses on:1) the origin of semi-continuous reflections within acoustic basement of the OJP based on synthetic seismogram modeling and DSDP/ODP results; 2) the relationship between the OJP and its neighboring Nauru and Lyra basins based on stratigraphic and structural analysis of MCS and SCS data; 3) the development of Tauu atoll on the southern flank of the OJP based on stratigraphic and structural analysis of MCS and SCS data integrated with DSDP/ODP results. Our initial results suggest that: 1)the semi-continuous reflections are probably thick, flat igneous flows/sill or flows/sills interbedded with sediment; 2) the transition between the Nauru Basin and the OJP is relatively smooth, implying that massive OJP and Nauru Basin magmatism were contemporaneous and geographically continuous, whereas the transition between the Lyra Basin and the northern flank of the OJP is faulted, characterized by horst and graben structures; 3) strong reflections (lava flows or a volcaniclastic wedge) emanating lie beneath sediment but above OJP basement, indicating a Tertiary, probably Paleogene, age for formation of the atoll.
DE: 8137 Hotspots, large igneous provinces, and flood basalt volcanism
SC: Tectonophysics [T]
MN: Fall Meeting 2005