| Project/Area Number |
62460043
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体地球物理学
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| Research Institution | Toyama University |
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Principal Investigator |
KAWADA Kunio Faculty of Science,Toyama University, 理学部, 助手 (20019003)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Takehiko College of Liberal Arts, Toyama University, 教育部, 教授 (80019257)
FUNAKI Minoru Division of Data Collection and Processing, National Institute of Polar Research, 資料系, 助手 (10132713)
SAKAI Hideo Faculty of Science, Toyama University, 理学部, 助手 (30134993)
HIROOKA Kimio Faculty of Science, Toyama University, 理学部, 教授 (30029467)
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| Project Period (FY) |
1987 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | Snow and ice involving volcanic Ashes / Magnetic particle / Snow grains / Acquisition of the natural remanent magnetization / 地球磁場 / 配向 / 火山灰中の磁性物質 / 雪氷中の汚れ層 |
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| Research Abstract |
The purpose of this project was to investigate the acquisition mechanisms of the natural remanent magnetization(NRM) of dirt-ice layers involving fine volcanic ashes found in the ice sheet of Antarctica. For this purpose, the acquisition process of NRM for dirt-snows in about -10゜C and -20゜C laboratories was studied by using artificial snow samples.
Aritificial snow samples for these experiments were made by mixing sorted snow grains and fine magnetic minerals. Dry dirt-snows acquired NRM toward the geomagnetic field(GMF) direction, although the NRM direction shifted toward flat maintaining northward declination after several days. It seems to be an important fact to explain the mechanisms of NRM acquisition that the metamorphism of snow set fine magnetic particles free. Then the magnetization of particles tend to turn toward GMF direction and stick to another parts of snow grains. In the case of dry snow samples, metanorphism of snow is made progress by the sintering of snow grains. In the process of moving of H_2O molecules to the narrow part, many magnetic particles free itself from the surface of snow grains, and may turn to the GMF direction. These particles collect on the narrow part or the grain boundaries and have fixed directions of NRM in the course of time. In the case of wet snows involving magnetic particles, they have thin water layer on the surface of snow grains. Therefore it is not difficult to set the magnetic particles free and to acquire the NRM when the melt water refreezed. Microscope observations of the dirt-snows thin sections proved that the NRM was acquired when the metanorphism of snows developed.
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