Examination of grain fabric inferred from the anisotropy of magnetic susceptibility using the X-ray CT method and the fabric map method
| Project/Area Number |
18540457
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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 |
Geology
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| Research Institution | Osaka Institute of Technology |
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Principal Investigator |
YOKOKAWA Miwa Osaka Institute of Technology, Faculty of Information Science and Technology, Associate Professor (30240188)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHIDA Akira Doshisha University, Faculty of Engineering, Professor (30164974)
NARUSE Hajime Chiba University, Graduate School of Sciences, Associate Professor (40362438)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,670,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥270,000)
Fiscal Year 2007: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2006: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | grain fabric / X-ray CT method / anisotropy of magnetic susceptibility / fabric map / parallel lamination / Toyoura quartz sand / chemical composition / magnetic features / 地質学 / プレーンベッド / 砂床上昇速度 / 水路実験 |
|---|
| Research Abstract |
The anisotropy of magnetic susceptibility (AMS) of sand-sized sediments has been believed to indicate the preferred grain orientation of the sediments. No study, however, has been verified this assumption. This project aimed to examine what generate the AMS of sand-sized sediments, using X-ray CT method and the fabric map method.
At first, grain fabric of parallel-lamination is examined by three methods mentioned above. At the same time, we examined the effect of bed-aggradation rate on the formation and grain fabric of parallel-lamination. A new method, density-based cluster analysis that deal with the dominant combinations of shapes and orientation of grains, was developed to analyze the X-ray CT data. It is revealed that the bed-aggradation rate effects on the features of the parallel-laminations and the combination of the shapes and orientation of the grains. In addition, averaged angles of grain imblication obtained from the three methods agreed within their error ranges.
Next, we examined the mineral and chemical compositions and the magnetic features of the "Toyoura quartz sand", which is commonly used for the flume experiments; to determine the mineral that contribute the AMS. As the results, it is revealed that the "Toyoura quartz sand" consists of quartz, plagioclase, potassium feldspar, amphibole, garnet, rutile, biotite, ilmenite, and magnetite. Ilmenite grains mainly contribute the magnetic susceptibility in this material. Magnetic minerals and non-magnetic minerals were divided by the CT values which correspond to the theoretical values of X-ray linear attenuation coefficient for each mineral. The results obtained by three methods for settling experiments showed that AMS showed the preferred grain orientations of magnetic minerals rather than bulk sediments. Samples those of grain flow experiments show different distribution for the three methods. More analyses such as for wider range of X-ray CT data will be needed to solve the problem.
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Report
(3 results)
Research Products
(24 results)
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[Presentation] Comparison among four methods of measurement of the grain orientation fabric by experiment and natural parallel-laminated deposits:image analysis,photometric method,magnetic method and X-rays CT image2006
Author(s)
Taniguchi, A, Naruse, H., Yokokawa, M., Hayashida, A., and Masuda, F.
Organizer
ISC2006 (International Sedimentological Congress)
Place of Presentation
福岡国際会議場
Year and Date
2006-08-29
Description
「研究成果報告書概要(和文)」より
Related Report
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[Presentation] Are the changes in sediment concentration recorded by the three-dimensional grain fabric in plane-bed deposits?Analyses using the X-ray microtomography2006
Author(s)
Nishio, T., Nakamura, Y., Yamamura, R., Iwata, H., Yokokawa, M., Naruse, H., Tsuchiyama, A., Uesugi, K., Nakano, T., Endo, N., and Yamaji, A.
Organizer
ISC2006 (International Sedimentological Congress)
Place of Presentation
福岡国際会議場
Year and Date
2006-08-29
Description
「研究成果報告書概要(和文)」より
Related Report
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