| Project/Area Number |
18K18789
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 17:Earth and planetary science and related fields
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| Research Institution | Kochi University |
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Principal Investigator |
YAMAMOTO YUHJI 高知大学, 教育研究部総合科学系複合領域科学部門, 教授 (00452699)
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| Co-Investigator(Kenkyū-buntansha) |
諸野 祐樹 国立研究開発法人海洋研究開発機構, 超先鋭研究開発部門(高知コア研究所), 上席研究員 (30421845)
山崎 俊嗣 東京大学, 大気海洋研究所, 教授 (80344125)
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| Project Period (FY) |
2018-06-29 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000)
Fiscal Year 2020: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2019: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2018: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
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| Keywords | 磁性細菌 / 残留磁化 / 古地磁気強度 / 古地磁気強度 ３．研究課題名 / 古地磁気 |
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| Outline of Final Research Achievements |
Using magnetotactic bacteria cells, a group of samples for magnetic measurement was prepared through analog experiments simulating the “early stages of sediment formation”. The properties of the acquired natural remanent magnetization (NRM) and the relative paleomagnetic intensity (RPI) index were considered. In the sample group in which the cells were highly efficiently oriented in response to the applied magnetic field, the NRM intensity increased nonlinearly in accordance with the tanh function as the applied magnetic field strength increased. On the other hand, in the sample group with low efficiency orientation, the NRM intensity increased linearly with the increase in the applied magnetic field intensity. The RPI index also tended to approach the values reported for actual natural marine sediments, suggesting that biological disturbance processes after initial deposition may be important in the magnetization acquisition mechanism of biogenic magnetite.
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| Academic Significance and Societal Importance of the Research Achievements |
地球システム進化を探るうえで，海底堆積物のNRMから推定できる古地球磁場の情報は重要である。このNRMは，磁性細菌に起源をもつ生物源磁鉄鉱にも担われているが，NRMの獲得過程や，獲得されるNRMの性質については未解明の部分が多い。本研究では，実際に磁性細菌の細胞を用いて，生物源磁鉄鉱がNRMを獲得する過程のアナログ実験と磁気分析を行い，獲得される残留磁化の性質を検討した。その結果，改めて，実際の天然堆積物のNRM獲得過程では，生物の活動によって磁性粒子が擾乱される過程が重要であることが認識されるなど，信頼性の高い古地球磁場情報の推定に資する成果が得られた。
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