High-pressure and high-temperature experiments of phase equilibria on armalcolite for the detailed analysis of P-T path of ultrahigh-temperature granulites

2016 Fiscal Year Final Research Report

• Project/Area Number: 25400516
• 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: Ehime University
• Principal Investigator: Kawasaki Toshisuke 愛媛大学, 理学部, 研究員 (50136363)
• Project Period (FY): 2013-04-01 – 2017-03-31
• Keywords: アーマルコライト / イルメナイト / ルチル / シュードブルッカイト / ウルボスピネル / 超高温変成作用の指標鉱物 / 高温高圧再現実験 / 酸素分圧

Outline of Final Research Achievements

This is the report of the investigation to clarify the P-T conditions for the armalcolite stability field through the high-pressure experiments at pressures 6～12 kbar and temperatures 900～1100℃ corresponding to the ultrahigh-temperature metamorphic conditions under controlling the oxygen fugacity (logPO2=-10～-11). In the TiO2-FeO-MgO system with bulk of 0.15<XMg<0.2, we found that the assemblage of armalcolite + ilmenite + rule is stable at 8 kbar and more than 900～950℃. This indicates Fe-rich armalcolite would be stable at pressures and temperatures conditions corresponding to the ultrahigh-temperature metamorphism under oxdising conditions (logPO2=-10～-11). We conclude the Fe-rich armalcolite would be a new index mineral for ultrahigh-temperature metamorphism.

Free Research Field

実験岩石学