| Project/Area Number |
15340166
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geology
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| Research Institution | Chiba University |
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Principal Investigator |
ITO Makoto Chiba University, Department of Earth Sciences, Professor, 理学部, 教授 (10201930)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUKAWA Masaki Tokyo Gakugei University, Department of Science, Professor, 教育学部, 教授 (30127914)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2004: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2003: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | greenhouse / icehouse / paleohydrology / fluvial system / channel belt / sinuosity / sequence / discharge / 氷室規 / 河川堆積物 / 下部白亜系 / 堆積シーケンス / 河川流路 / ストーム / 土壌化 / 相対的海水準 / 側方付加 / 温暖化 / 前期白亜紀 / アジア大陸 / 古気候 / 乾燥化 / モンゴル-オホーツク海 |
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| Research Abstract |
Methodologies of quantitative characterization of morphology and paleohydrology of ancient fluvial systems were investigated on the basis of published empirical relationships among several variables, which represent hydraulic features of modern fluvial systems. Architectural analyses of ancient fluvial successions were used for the better understand of spatial and temporal variations in morphology and paleohydraulic features of ancient fluvial system. Six-hold hierarchy of bounding surfaces and their depositional units were identified from outcrop analysis of ancient fluvial successions. The most laterally continuous bounding surface defines a channel belt and the least laterally continuous bounding surface is a reactivation surface within a bar deposit. On the basis of stacking patterns and lithofacies features of component channel deposits, fluvial styles in an overall transgressive succession does not exhibit any distinct change compared with the standard fluvial sequence-stratigraphic model. In terms of comparison of fluvial systems developed during greenhouse and icehouse stages, distinct variations in morphology, sinuosity and paleohydrology were not necessarily evident and fluvial systems are interpreted not to have intimately responded to changed in paleoclimates. Lower Cretaceous fluvial systems developed in Japan and northeastern China were investigated in terms of spatial variations in fluvial styles and paleohydrology along the eastern margin of the Asian continent. Both areas are characterized by fluvial systems largely similar in paleohydrology, such as average annual discharge, channel width, sinuosity, and channel belt width. Overall, paleodischarge, and channel-belt width decreased with the increase in sinuosity of fluvial channels in response to decline of topographic surfaces in later stage of in filling of sedimentary basins.
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