| Project/Area Number |
25870147
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Stratigraphy/Paleontology
Geochemistry/Cosmochemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SHIRAI Kotaro 東京大学, 大気海洋研究所, 助教 (70463908)
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| Project Period (FY) |
2013-04-01 – 2015-03-31
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| Project Status |
Completed (Fiscal Year 2014)
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| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2014: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2013: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
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| Keywords | シャコガイ / 極端現象 / 古環境復元 / Sr/Ca比 / 古環境指標 / 成長線解析 / 微小領域分析 / 台風 / 化石 / 微量元素 / 安定同位体 |
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| Outline of Final Research Achievements |
For the understanding and future prediction of extreme events, establishing a new method to reconstruct past-environment at diurnal scale is required. Giant clam holds great advantages for this purpose, namely the shell forms daily growth line which enable to identify a time axis at hourly scale, and holds continuous and long term environmental records up to few hundreds years. The aim of this study is to examine the giant clam shell as very high resolution past environmental proxy. Incremental width of daily growth line in fossil shell from Holocene climatic optimum showed clear seasonal fluctuation, wide in summer while narrow in winter. The low-resolution profile of the shell Sr/Ca and Mg/Ca ratio showed seasonal fluctuation along a growth direction. The 2-micrometer resolution profile of Sr/Ca ratio in the fossil shell showed clear diurnal fluctuation, indicating daily insolation cycles.
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