2020 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 – 2023-03-31
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| Keywords | Izu-Oshima / submarine eruption / FTIR / volatiles / paleointensity / Quaternary |
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| Outline of Annual Research Achievements |
A full set of samples was selected from the collection of Izu-Oshima's submarine volcanic ridges held at the Geological Survey of Japan. Samples were selected following examination of rock thin sections and assessment of the sampling context recorded in videos of the sampling by Remotely Operated Vehicle (e.g. water depth, distance from ridge summit, coherent lava vs broken talus deposit). These measures were undertaken to ensure that targeted samples contained enough glass for successful analysis, and that samples were chosen according to those that can provide the most insight into the water depth at the time of eruption (i.e. were close to the eruptive vent and unlikely to have been significantly remobilised downslope after eruption). Samples were prepared as double-polished wafers for Fourier Transform Infra Red spectroscopy (FTIR) analysis of dissolved volatile concentrations (H2O and CO2) in glass. FTIR volatile analyses were begun and are ongoing, using FTIR imaging analysis technique where necessary for samples with high micro-crystallinity. Preliminary magnetic paleointensity analyses have confirmed the samples have sufficient signal for successful analysis.
Research results related to the use of FTIR volatile analysis for investigating eruption ages and dynamics of submarine eruptions were presented at the online Japan Geoscience Union annual meeting.
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| Current Status of Research Progress |
Current Status of Research Progress
4: Progress in research has been delayed.
Reason
Domestic travel restrictions due to the Covid-19 pandemic delayed the initial selection of samples until travel to GSJ was possible.
FTIR analyses have proceeded more slowly than anticipated due to i) restrictions on attendance and lab use during measures related to the Covid-19 pandemic and ii) temporary breaking of the FTIR apparatus, which reduced the time available for sample preparation and analysis.
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| Strategy for Future Research Activity |
Ongoing FTIR analyses will be completed and magnetic paleointensity will be measured. These volatile and paleointensity data will be combined with geochemical data and compared to known past variation in sea level and geochemistry to estimate eruption ages of the submarine ridges. Melt inclusions will be analysed for insight into magma mixing and storage processes, and sample porosity will be analysed for insight into eruption dynamics of submarine eruptions at different water depths.
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| Causes of Carryover |
Budget will be allocated to cover the costs of sample preparation, mounting and analysis; domestic travel for analysis and meetings with collaborators; and participation in domestic and international conferences (probably via online systems due to ongoing Covid-19 situation) for presentation of research results.
Costs of sample preparation and analysis include consumable plastic sleeves for Selfrag sample disaggregation, KBr analytical windows and sample preparation materials (e.g. silica carbide papers for grinding, gelatin capsules for sample storage) for FTIR analysis, samples holders and indium for mounting samples for SIMS analysis, and argon gas used in LA-ICP-MS analysis.
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