2000 Fiscal Year Final Research Report Summary
Environmental changes from greenhouse earth to icehouse earth through a study of chalk/black shale sequence
| Project/Area Number |
10304039
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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 | 一般 |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TAIRA Asahiko Ocean Research Institute, The University of Tokyo Professor, 海洋研究所, 教授 (50112272)
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| Co-Investigator(Kenkyū-buntansha) |
MURAYAMA Masashi Kochi Univ., Marine Core Research Center, Associate Prof., 海洋コアセンター, 助教授 (50261350)
ISHII Teruaki Ocean Research Institute, The University of Tokyo Associate Prof., 海洋研究所, 助教授 (80111582)
TOKUYAMA Hidekazu Ocean Research Institute, The University of Tokyo Professor, 海洋研究所, 教授 (10107451)
OKADA Makoto Ibaragi Univ., Faculty of Scence, Assistant Prof., 理学部, 助手 (00250978)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Cretaceous / Chalk / Black Shale / Anoxic Event / Cyanobacteria / Carbon Isotope / Sulfur Isotope / Blue Tide |
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| Research Abstract |
A chalk/black shale sequence exposed in the Appenine Mis. in Italy was investigated in order to reveal the basic marine environmental setting in the Cretaceous warm period. Cenomanian/Turonian black shale (Bonalleli horizon) showed the following characteristics.
1. The source of organic matter is bacterial origin (Cyanobacteria and photosynthesic bacteria).
2. Large excursion of sulfur isotope suggests strong ocean stratification with anoxic bottom water. About 30% of total sulfur from the global ocean was fixed as pyrite. The ocean surface had to be highly oligotrophic.
3. Occasional instability of stratified ocean and upwelling caused events of nutrient supply to the surface that caused radiolarian blooming.
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