2018 Fiscal Year Research-status Report
Experimental modeling of diamond crystallization from C-O-H fluid under controlled oxygen fugacity
| Project/Area Number |
17K14417
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| Research Institution | Ehime University |
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Principal Investigator |
CHERTKOVA N 愛媛大学, 地球深部ダイナミクス研究センター, 特定研究員 (00791774)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | diamond anvil cell / in situ spectroscopy / C-O-H fluid speciation / diamond stability field |
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| Outline of Annual Research Achievements |
The plan for FY 2018 included in situ spectroscopic analysis of the fluids and solid phases, which constitute environment for diamond formation, at the high-pressure and high-temperature conditions. The new assembly of the diamond anvil cell with large optical access to the sample was developed this year particularly for infrared spectroscopy. In situ infrared and Raman measurements of the C-O-H fluid species, coexisting with the silicate minerals of eclogite assembly, were performed in the stability field of diamond. Quenching to room temperature and opening of the experimental cell were accompanied by the change in fluid state, underlining the importance of obtained in situ data. Research findings of this project were reported at the international meetings.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
After establishing of the procedure for loading of basaltic glass with methane hydrate fluid source into the sample chamber of diamond anvil cell, experiments were performed in the temperature range to 1000 °C and pressures exceeding 5 GPa. Water and methane were detected after decomposition of methane hydrate upon heating, with the formation of homogeneous C-O-H fluid at higher temperatures. In collaboration with Okayama University, combined infrared and Raman spectroscopic analysis was carried out in order to gain comprehensive information about the types of species and chemical characteristics of the phases observed during experiments. Developed techniques and instrumentation helped to achieve the tasks, which were set in the original plan.
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| Strategy for Future Research Activity |
Research work in the next fiscal year will be concentrated on data processing, comparison of the experimental data with the available large dataset of chemical, structural and mineral analyses of inclusions in natural diamonds. Obtained trends will be used to discuss the models of diamond formation and the reconstruction of conditions for diamond crystallization in the Earth’s mantle. Experimental results will be summarized in the manuscripts prepared for publication in the international scientific journals.
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| Causes of Carryover |
The carryover will be used to cover publication expenses.
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