| Project/Area Number |
10640447
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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 |
Stratigraphy/Paleontology
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| Research Institution | AKITA UNIVERSITY |
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Principal Investigator |
SATO Tokiyuki Faculty of Eng. And Res. Sci., Akita Univ. Assoc. Professor, 工学資源学部, 助教授 (60241668)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAYAMA Toshiaki Dep. Social and Inf. Sci., Jumonji Univ. Professor, 社会情報学部, 教授 (40004361)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1999: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1998: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | calcareous nannofossil / Paleoceanography / Pliocene / Pleistocene / Coccolithus pelagicus / Isthmus of Panama / パナマ地峡 / 寒冷種 / 鮮新世〜更新世 / Coccolithus Pelagicus |
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| Research Abstract |
The Pliocene to Pleistocene geographical distributions of calcareous nannofossils is analyzed using DSDO-ODP samples collected from the Pacific, Atlantic, and Indian Ocean to reconstruct paleoceanographic condition during last two million years. The distribution patterns of Coccolithus pelagicus in the equatorial Pacific and Caribbean Sea is interpreted as evidence of new current system, which was created by the appearance of the Isthmus of Panama in 2.75Ma. This event is strongly related to both the drop of the sea level recognized in the Bahama region in the Caribbean Sea, and increasing of the sea ice in the Arctic region.
Focusing to this event, calcareous nannofossils in the samples collected from the low to high latitude of the Pacific Ocean are anakyzed. The assemblages characterized by the cold water species are limited in the higher latitude region. Offshore Iwaki, Miyakojima Island, and ODP Holes in the middle to low latitude regions are characterized by the warm water nannofossils such as Discoasters. The boundary between these paleobiogeography is situsted in the 40° before 2.75Ma. However, the evidence of abundancy of Coccolithus pelagicus indicates the occurrence of southward movement of this boundary after 2.75Ma.
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