2021 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 |
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 – 2023-03-31
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Keywords | FTIR / H2O / submarine eruption |
Outline of Annual Research Achievements |
Samples of submarine basaltic lavas from past ridge eruptions of Izu-Oshima were prepared as sample wafers for analysis of dissolved H2O contents by FTIR. The H2O content is a record of the pressure at which the eruption happened. It is intended to compare this pressure record with the water depth of the eruption, and by consideration of past sea level to estimate eruption age. Magnetic paleointensity of these samples has also been measured for comparison with past variations in magnetic field intensity, and these datasets will be combined to improve estimation of eruption age. Several samples were analysed by FTIR but the unexpected presence of many tiny crystals in the glassy groundmass prevented accurate measurement of H2O by FTIR. In FY2022 a new sample preparation technique for obtaining suitable glass for analysis will be tested. FTIR analysis of melt inclusions will also proceed.
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Current Status of Research Progress |
Current Status of Research Progress
4: Progress in research has been delayed.
Reason
During planned FTIR analysis it was found that many samples have too many tiny crystals in the glassy groundmass for successful transmission FTIR analysis of glass volatile contents after preparation as free-standing wafers. It was planned to try a new preparation technique of disaggregation by Selfrag and picking of glass shards, but the Selfrag equipment is broken and repair cannot occur until foreign engineer can enter Japan. Other samples that might be sufficiently glassy for successful analysis by standard preparation were also selected. However, there was not time to prepare them before the FTIR became unavailable due to breaking and then removal/replacement.
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Strategy for Future Research Activity |
Arrangements have been made to proceed with the new preparation method by accessing a Selfrag instrument at another institution. It is hoped that after Selfrag disaggregation it will be possible to successfully perform FTIR analysis as planned. The FTIR has been replaced and will be available in FY2022. Samples will also be prepared for melt inclusion analysis after disaggregation by Selfrag.
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Causes of Carryover |
Due to ongoing disruption due to Covid-19 there was less travel and conference attendance than expected in the original budget. There were also delays to sample analysis caused by broken equipment (FTIR, Selfrag) which means that fewer lab consumables than expected were required. These will be purchased and used in the next year instead.
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