2006 Fiscal Year Final Research Report Summary
Experimental autostratigraphy of fluvio-delatic systems on the basis of the theory of shoreline autoretreat
| Project/Area Number |
15340171
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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 | Nagasaki University |
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Principal Investigator |
MUTO Tetsuji Nagasaki University, Faculty of Environmental Studies, Professor, 環境科学部, 教授 (70212248)
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| Project Period (FY) |
2003 – 2006
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| Keywords | river / delta / sedimentology / sea-level change / forcing / genetic stratigraphy / non-equilibrium / autostratigraphy |
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| Research Abstract |
Autostratigraphy, advocated in this research project in terms of the intrinsic non-equilibrium response is the stratigraphy generated by large-scale autogenic processes, and needs to be heeded because of a current over-reliance on allogenic controls in sequence stratigraphy. Key principles of autostratigraphy, emerging from the theory of autoretreat and a new understanding of alluvial grade, derive from the non-equilibrium stratigraphic response, i.e. the general lack of equilibrium configuration, of depositional systems. The non-equilibrium behavior of fluvial deltas during times (7) of steady dynamic forcing leads to variable stratigraphic response that is the inevitable result of length (D) and time (τ) scaling particular to the depositional system, rather than necessarily reflecting any sudden or unsteady change in the rate of allogenic forcing. Some abrupt breaks in the stratigraphic record are not necessarily associated with changes in allogenic conditions but can result from purely autogenic processes of the system. When Tis comparable to or longer than τ, (1) the depositional system takes the non-equilibrium, large-scale autogenic response, (2) the superposition of autogenic and allogenic components of the forcing is prominently nonlinear, and thus (3) sequence stratigraphic models that have been built on the assumption of equilibrium response are incorrect. Autostratigraphic analysis makes it possible to detect and identify complex autogenic responses and unsteady allogenic events in the stratigraphic record, by quantifying a temporal change in the magnitude of D. Autostratigraphy thus functions as a 'norm' for genetic stratigraphy.
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Research Products
(24 results)
