| Project/Area Number |
14540458
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
地球化学
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| Research Institution | Independent Administrative Institution, Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
HARADA Naomi Independent Administrative Institution, Japan Agency for Marine-Earth Science and Technology, Institute of Observational Research for Global Change, Sub group leader, 地球環境観測研究センター, サブリーダー (70344281)
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| Co-Investigator(Kenkyū-buntansha) |
AHAGON Naokazu Hokkaido University, Associate Professor, 大学院・理学研究院, 助教授 (30359161)
KIMOTO Katsunori Independent Administrative Institution, Japan Agency for Marine-Earth Science and Technology, Institute of Observational Research for Global Change, Researcher, 地球環境観測研究センター, 研究員 (40359162)
UCHIDA Masao Independent Administrative Institution, Japan Agency for Marine-Earth Science and Technology, Institute of Observational Research for Global Change, Researcher, 地球環境観測研究センター, 研究員 (50344289)
YAMAZAKI Toshitsugu AIST, Geological Survey of Japan, Research group leader, 海洋資源研究部門, 研究グループ長 (80344125)
ASAHARA Yoshihiro Nagoya University, Assistant Professor, 大学院・環境学研究科, 助手 (10281065)
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| Project Period (FY) |
2002 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2003: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2002: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Paleoceanography / Marine sediments / Biomarker / Both hemispheres / 国際研究者交流 / 南太平洋 / 堆積物 / アルケノン / 古水温 / 二酸化炭素分圧 / 有孔虫化石 / 古地磁気 / 風成塵 / 14C年代 / 中層水循環 / 基礎生産量 / 南北両大陸 |
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| Research Abstract |
During the first year of the term of this grant, we couls obtained the data set of alkenone sea surface temperature and oxygen isotopic profile of planktonic foraminifera over the past 400 ka recorded in the sedimnet cores collected in the northwestern North Pacific. In the second year, total six long-size sediment cores were collected in the Chilean marginal area, Magellan strait, south eastern Indian Ridge, and Kelgueren Plateau during r/V MIRAI MR03-K04 cruise. During the third and forth years, chemical paleo proxides, alkenone, oxygen isotopic ratio of planktonic foraminifera, opal, 210Pb, radiocarbon, foraminiferal assemblanges of sediment cores collected in the above area has been analyzed onshore.
On the other hand, for the sediment cores in high latitude of the North Pacific and the Okhotsk Sea, sea surface temperature was reconstructed with decadal-centennial time resolution over the past 100ka. In addition, variation of ventilation of water mass from the intermediate to deep w
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as reconstructed in the northwestern North Pacific with centennial - millennial time scale resulution. As a result, ventilation speed was rapidly down at the Bolling-Allorod interstatial (12 ka) when is just before the Younger Dryas cooling period (11ka). This slow down of ventilation of the intermediate water mass at 12 ka corresponded to the timing of enormous methane dydrate release recorded in the sediment cores Off Tokachi area. The change in the ventilation of intermediate water mass might affect the regional carbon cycle in the northwestern North Pacific.
In order to reconstruct of sea surface temperature at the Pacific side mouth of Magellan strait, alkenon, which is a robust paleothermometer was analyzed. Alkenon temperature varied from 8.7℃ to 12℃ and garadually increased from the bottom to 600cm depth. We could find a sharp decrease in alkenon temperature (<10℃) at 520cm depth. After the low alkenone temperature event at 520cm depth, alkenone teperature again up to 12℃. According to the ^<14>C data or core top, the dramatic cooling of alkenone temperature had started at 4-5 kyrBP.
More high quality sediments cores from the southern hemisphiere are necessary to compare with teh paleoenvironmental changes in the northern hemisphere with high time resolution. Less
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