2023 Fiscal Year Research-status Report
A new method for dating late Quaternary submarine eruptions and its use to investigate magmatic and eruptive processes at island arc volcanoes
| Project/Area Number |
20K14586
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| Research Institution | Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
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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| Project Period (FY) |
2020-04-01 – 2025-03-31
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| Keywords | paleomagnetism / paleointensity / eruption age dating / submarine eruption |
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| Outline of Annual Research Achievements |
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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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
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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| Strategy for Future Research Activity |
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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| Causes of Carryover |
Remaining budget will be used primarily to undertake melt inclusion analysis (consumables e.g. indium for sample preparation, transport and accommodation for SIMS analysis). This could not take place in FY2023 due to other schedule commitments such as research cruises, so was deferred to FY2024. Other budget uses will be participation in domestic and international conferences to present research results.
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