2005 Fiscal Year Final Research Report Summary
ENVIRONMENTAL MAGNETISM OF QUATERNARY MARINE SEDIMENTS FROM THE ANTARCTIC REGION AND ITS PALEOCLIMATE IMPLICATIONS.
| Project/Area Number |
15540442
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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 | DAITO BUNKA UNIVERSITY |
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Principal Investigator |
NAKAI Mutsumi DAITO-BUNKA UNIVERSITY, FUCULTY OF LITERATURE, ASSOCIATE PROFESSOR, 文学部, 助教授 (70317650)
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| Co-Investigator(Kenkyū-buntansha) |
MORIJIRI Rie NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY (AIST), GEOLOGICAL SURVEY OF JAPAN, SENIOR RESEARCHER, 地質情報研究部門, 主任研究員 (10358187)
UENO Naoko TOYO UNIVERSITY, FUCULTY OF LITERATURE, PROFESSOR, 文学部, 教授 (10058109)
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| Project Period (FY) |
2003 – 2005
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| Keywords | marine sediment / Antarctica / rock magnetism / paleomagnetism / grain distribution / Quaternary / environmental magnetism / 氷床 |
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| Research Abstract |
Paleomagnetic and rock magnetic studies were performed on 22 sediment core samples taken by the Antarctic Geological and Geophysical Research Project of the Japan National Oil Corporation (JNOC). These cores were transferred to the Geological Survey of Japan. These cores did not suffer serious magnetic damage, though they have been kept in a room temperature since 2002 after being kept refrigerated for more than 10 years. Our results of measurements of natural remanent magnetization (NRM) and magnetic susceptibility agree with the results of the JNOC reports. We measured some rock magnetic parameters, anhysteretic remanent magnetization (ARM), saturation isothermal remanent magnetization (SIRM), anisotropy of magnetic susceptibility (AMS) and high and low temperature thermo-magnetic curves. In addition, we measured grain size distributions of some samples. The grain size distribution shows these sediments came from Antarctica transported with ice sheets. Rock magnetic results show magnetic minerals of these sediments are magnetite and maghemite. We could not find iron sulfide. Therefore, we concluded Quaternary marine environment around Antarctica were oxygen rich.
We correlated grain size distributions and rock-magnetic parameters in marine sediments from off Wilkesland, East Antarctica (60-75deg.S, 110-180deg.E), because the rock magnetic parameters show several clear changes. These parameters are S-ratio (back magnetic field : 0.1T), Hrc/Hc, Mr/Ms, and SIRM/k. As a result, clear correlation was found between grain size distribution and both S-ratio and SIRM/k. The age at bottom of these core are about 0.7Ma. We concluded these rock magnetic parameter changes caused by decrease and increase of ice sheets.
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