| Project/Area Number |
16253002
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
Solid earth and planetary physics
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| Research Institution | Independent Administrative Institution, Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
FUKAO Yoshio Independent Administrative Institution, Japan Agency for Marine-Earth Science and Technology Institute for Research on Earth Evolution, Director-General, 地球内部変動研究センター, センター長 (10022708)
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| Co-Investigator(Kenkyū-buntansha) |
SUETSUGU Daisuke Independent Administrative Institution, Institute for Research on Earth Evolution, Group Leader, 地球内部変動研究センター, グループリーダー (20359178)
SHIOBARA Hajime University of Tokyo, Earthquake Research Institute, Associate Professor, 地震研究所, 助教授 (60211950)
HANYU Takeshi Independent Administrative Institution, Institute for Research on Earth Evolution, Senior Scientist, 地球内部変動研究センター, 研究員 (50359197)
SUGIOKA Hiroko Independent Administrative Institution, Institute for Research on Earth Evolution, Technical Scientist, 地球内部変動研究センター, 研究員 (00359184)
SUZUKI Katsuhiko Independent Administrative Institution, Institute for Research on Earth Evolution, Group Leader, 地球内部変動研究センター, グループリーダー (70251329)
一瀬 建日 独立行政法人海洋研究開発機構, 地球内部変動研究センター, 研究員 (60359180)
仲 二郎 独立行政法人海洋研究開発機構, 地球内部変動研究センター, 研究員 (10344300)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥37,310,000 (Direct Cost: ¥28,700,000、Indirect Cost: ¥8,610,000)
Fiscal Year 2006: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
Fiscal Year 2005: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000)
Fiscal Year 2004: ¥30,940,000 (Direct Cost: ¥23,800,000、Indirect Cost: ¥7,140,000)
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| Keywords | hot spot / superplume / broadband ocean bottom seismograph / volcanic rock / dive survey / 表面波トモグラフィー / マントル遷移層 / ドレッジ / 海底ノイズ |
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| Research Abstract |
We deployed 10 broadband ocean bottom seismographs to improve seismic resolution for mantle structure beneath the Polynesian region to obtain detailed structure of mantle plumes. We made a sampling survey of volcanic rocks with the submersible "SHINKAI-6500" of JAMSTEC. The obtained results are as follows.
1. We determined the upper mantle S-velocity model beneath French Polynesia down to 200 km. Slow velocity anomalies were found beneath all the hot spots, while their maximum depths are different beneath different hot spots. Beneath the Society and McDonald hot spots, slow anomalies extend down at least to 200 km.
2. Thickness of the mantle transition zone was determined by a receiver function method. We detected a thin transition zone only beneath the Society hot spot and did not find significant thickness anomalies beneath other stations, indicating that mantle plumes from the lower to upper mantle in French Polynesia are not broad but is localized beneath the Society hot spot.
3. We determined P-velocity structure beneath Polynesia by travel time tomography using P-wave arrival times and differential P-wave arrival times among stations. There is a broad slow velocity anomaly at depths greater than 1000 km in the lower mantle. Slow anomalies are narrow at depths from 1000 to the bottom of the upper mantle. The upper mantle structure is relatively ill-resolved by the present data. A narrow slow anomaly in the lower mantle located beneath the Society hot spot suggests that a mantle plume is ascending from the lower mantle to the Society hot spot.
4. We could obtain good rock samples with "SHINKAI-6500" on the seafloor along the Cook-Austral islands. Composition of the seafloor rock samples are distinct from those obtained on the land area of the Cook-Austral islands, suggesting a magma source was changed with a growth of a hot spot volcano.
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