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2003 Fiscal Year Final Research Report Summary

High-resolution reconstruction of environmental change off the east coast of Japan since the last 50,000 years reconded in a marine sediment core.

Research Project

Project/Area Number 13304040
Research Category

Grant-in-Aid for Scientific Research (A)

Allocation TypeSingle-year Grants
Section一般
Research Field Stratigraphy/Paleontology
Research InstitutionHokkaido University

Principal Investigator

OBA Tadamichi  Hokkaido University, Graduate School of Environmental Science, Professor, 大学院・地球環境科学研究科, 教授 (60013588)

Co-Investigator(Kenkyū-buntansha) YAMAMOTO Masanobu  Hokkaido University, Graduate School of Environmental Science, Associate Professor, 大学院・地球環境科学研究科, 助教授 (60332475)
NAGAO Seiya  Hokkaido University, Graduate School of Environmental Science, Associate Professor, 大学院・地球環境科学研究科, 助教授 (20343014)
OKADA Hisatake  Hokkaido University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (80111334)
NARITA Hisashi  Hokkaido University, Graduate School of Environmental Science, Assistant Professor, 大学院・地球環境科学研究科, 助手 (50250501)
IRINO Tomohisa  Hokkaido University, Graduate School of Environmental Science, Assistant Professor, 大学院・地球環境科学研究科, 助手 (70332476)
Project Period (FY) 2001 – 2003
KeywordsPaleoenvironment / Off east coast of Japan / Glacial and interglacial age / Marine sediment core / Microfossils / Oxygen and carbon isotope / Paleotemperature / Paleoclimate
Research Abstract

The northwest Pacific, where the cold Oyashio and the warm Kuroshio Currents meet each other today, is the most sensitive region in the North Pacific for monitoring the migration of the western boundary corrects in response to the past climatic change. A long core (45.82 m length) was recovered from 2,224 m water depths off the central Japan during the IMAGES cruise in 2001. A multi-disciplinary study was carried out on the core by analyzing the following research items : color, grain size, mineral composition, paleomagnetism, δ^<18>O, δ^<13>C Opal, CaCO_3, species of diatoms, coccolithophorids, radiolaria, planktonic foraminifera and benthic foraminifera, CaCO_3 preservation, Uk37', TOC, C/N, δ^<13>C_<TOC>, δ^<15>N_<TOC>, biomakers and pollen. The following main results ware obtained. The δ^<18>O curve of G.bulloides is similar to the standard oxygen isotope curve, suggesting continuous deposition over the last 145 ka. All warm water indices yielded by the four microfossil assemblages (diatoms, coccolith, radiolaria, planktonic foraminifera) show temperature decreases during the MIS 2 and 6, and increases during the MIS 5, although their correlation coefficients with each other are not always high (between 0.5 and 0,6). The Alkenon-derived temperature (19℃) at the core top agrees with the mean annual SST at present time in this region. The SST at the end of the MIS 2 was 13℃, which is seen today about 4.5 degree latitude north than the core site. Similar migrations in SST are inferred from the coiling ratio of N.pachyderma. The C/N ratio, δ^<13>C_<TOC> and δ^<15>N_<TOC> indicate that the TOC is mainly of marine origin, although terrestrial origin slightly increases during the MIS 6. The curve of the warm pollen index is similar to the δ^<18>O curve of G.bulloides, except for the MIS 6 and 5e when the land temperature changes inferred from the pollen curve precede the δ^<18>O curve.

  • Research Products

    (6 results)

All Other

All Publications (6 results)

  • [Publications] Oba T., Murayama M.: "Sea-surface tempemture and salinity changes in the northwest Pacific since the Last Glacial Maximum."J.Quaternary Sci.. 19. 1-12 (2004)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yamamoto, M.: "Have the tropical Pacific ocean-atmosphere interactions behaved as a driver of centennial- to orbital-scale climate changes?"Global Environmental Change in the Ocean and on Land. 265-278 (2004)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ono, Y., Irino, T.: "Southern migration of westerlies In the Northern Hemisphere PEP II transect during the Last Glacial Maximum"Quaternary International. 118-119. 13-22 (2004)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Oba T., Murayama M: "Sea-surface temperature and salinity changes in the northwest Pacific since the Last Glacial Maximum."J.Quaternary Sci.. 19(4). 1-12 (2004)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yamamoto, M.: "Have the tropical Pacific ocean-atmosphere interactions behaved as a driver of centennial-to orbital-scale climate changes?"Global Environmental Change in the Ocean and on Land (M.Shiyomi, H.Kawahata, H.Koizumi, Tsuda, Y.Awaya (eds), Terapub, Tokyo). 265-278 (2004)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Ono, Y., Irino, T.: "Southern migration of westerlies in the Northern Hemisphere PEP II transect during the Last Glacial Maximum"Quaternary International. Vol.118-119. 13-22 (2004)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2005-04-19  

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