| Project/Area Number |
10640451
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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 | KYUSHU UNIVERSITY |
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Principal Investigator |
NISHI Hiroshi Department of Earth Science, Graduate School of Social and Cultural studies, Kyushu University, Associate Professor., 大学院・比較社会文化研究科, 助教授 (20192685)
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| Co-Investigator(Kenkyū-buntansha) |
西 弘嗣 九州大学, 大学院・比較社会文化研究科, 助教授 (20192685)
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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 |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | Greenhouse / Cretaceous / Anoxic event / LPTM / BEE / Superplumes / 浮遊性有孔虫 / オルビトリナ石灰岩 / スーパープリューム / ガスハイドレート / 炭素同位体比スパイク |
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| Research Abstract |
In this study, we focused on changes of paleoenvironments and biofacies during greenhouse periods spanning 65 m. y.. The first period of greenhouse is the middle Cretaceous (Aptian to Turonian) when polarward distributions of tropical to subtropical species of corals and foramminifers occurred. Some five anoxic events marked by marine black muds containing abundant organic matters had been recorded on both continental shelf and deep marine environments, suggesting stagnation of ocean circulations. In contrasts, the late Cretaceous (Coniacian to Maastrichtian) indicates relatively cooler climate. The turnover age from hot to cool climates was bout 90 Ma.
The second period is the Late Paleocene Themal Maximum (LPTM). We recognized here the benthic extinction event (BEE) which is characterized by a faunal turmover from Paleocene assemblage consisting of oxic and eutoropic to Eocene anoxic and oligotropjic ones. However, no remarkable turnovers of planktonic foraminifers occurred during LPTM. These warm events resulted from the increase of greenhouse gasses released by intense volcanic activity of ridge systems/superplumes.
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