Thermodynamic model for volumetric property of hydrous magmas

Research Project

Project/Area Number	17K05707
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Petrology/Mineralogy/Economic geology
Research Institution	Okayama University
Principal Investigator	Yamashita Shigeru 岡山大学, 惑星物質研究所, 准教授 (30260665)
Project Period (FY)	2017-04-01 – 2020-03-31
Project Status	Completed (Fiscal Year 2019)
Budget Amount *help	¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000) Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2017: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Keywords	岩石鉱物鉱床学 / マグマ / 高温高圧実験 / 火山 / 実験岩石学 / 水 / 流体 / 岩石・鉱物・鉱床学
Outline of Final Research Achievements	The speciation of water in an albitic melt was studied in-situ at high pressure and high temperature using micro FTIR-Raman spectroscopy. The water speciation in the hydrous melt was found to be independent of pressure. This indicates that the standard volume change of the water speciation equilibrium is negligibly small, and hence the volumetric property of hydrous melts is independent of water speciation.
Academic Significance and Societal Importance of the Research Achievements	現在、マグマの上昇や固化の数値シミュレーションで広く用いられている含水マグマ体積モデルは、マグマに溶け込んでいる水を全て「H2O」として扱い、H2O分子とOH基を区別していない。それはしたがって、まったく経験的なモデルであるが、この研究の成果はそうしたモデルの妥当性と信頼性に熱力学的な根拠を与えるものである。