| 研究課題/領域番号 |
20K14586
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| 研究種目 |
若手研究
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| 配分区分 | 基金 |
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| 審査区分 |
小区分17040:固体地球科学関連
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| 研究機関 | 国立研究開発法人海洋研究開発機構 |
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研究代表者 |
McIntosh Iona 国立研究開発法人海洋研究開発機構, 海域地震火山部門(火山・地球内部研究センター), 研究員 (70780899)
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| 研究期間 (年度) |
2020-04-01 – 2025-03-31
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| 研究課題ステータス |
交付 (2023年度)
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| 配分額 *注記 |
4,160千円 (直接経費: 3,200千円、間接経費: 960千円)
2022年度: 1,820千円 (直接経費: 1,400千円、間接経費: 420千円)
2021年度: 1,560千円 (直接経費: 1,200千円、間接経費: 360千円)
2020年度: 780千円 (直接経費: 600千円、間接経費: 180千円)
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| キーワード | paleomagnetism / paleointensity / eruption age dating / submarine eruption / FTIR / H2O / Izu-Oshima / volatiles / Quaternary / Volatiles / Submarine eruptions |
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| 研究開始時の研究の概要 |
To assess future hazards of island arc volcanoes, we need to know when, why and how past eruptions occurred. However, the timing and processes of their submarine eruptions, and how these relate to their better studied subaerial eruptions, are poorly known. Focusing on Izu-Oshima’s submarine ridge eruptions, I will develop and apply a new method to date these late Quaternary eruptions for the first time. With this new time context I will constrain the temporal evolution of magmatic and eruptive processes that drive both submarine and subaerial basaltic eruptions and control their hazards.
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| 研究実績の概要 |
Basaltic rock samples from submarine ridges on the flanks of Izu-Oshima island were analysed for their rock magnetic properties. We tested if their magnetic paleointensity values could be used to estimate their eruption ages, by comparing the data to how regional geomagnetic paleointensity has varied over time. Samples from 3 different ridges were tested. Their paleointensity data are consistent with petrographical and geochemical age constraints and narrow the possible age range of these submarine ridge eruptions. The results demonstrate that magnetic paleointensity may be a useful tool for constraining eruption ages of Holocene/Late Pleistocene submarine volcanic rocks, which are often not possible to date by other methods. The findings have been published in Earth, Planets and Space.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
3: やや遅れている
理由
The main target of this research was to combine bulk rock geochemistry, rock magnetic paleointensity, and matrix glass volatile data to constrain eruption ages of submarine basaltic rocks. The geochemistry and paleointensity work has been successful and led to a journal publication. The matrix glass volatile work has not yet been successful due to inadequate suitable glass for analysis by FTIR (problems of detection limits and so on). Work is ongoing to find suitable matrix glass for successful FTIR volatile analysis. This includes preparing multiple rock samples as double-polished sample wafers (the original planned approach) and also trying to extract matrix glass from lightning-disaggregated samples (new approach).
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| 今後の研究の推進方策 |
I will continue to attempt to find suitable matrix glass for volatile analysis (to enable constraint of eruption age from the relationship between volatile content and past sea level change). This will include using lightning-disaggregation of samples in addition to the previous approach of sample wafer preparation. I will also focus on a secondary objective of the research, by analysing glassy melt inclusions to use their geochemistry and volatile contents to better constrain the magma storage conditions of the magmas that formed Izu-Oshima's submarine ridge eruptions.
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