Shear instability in solid-liquid two-phase system at high pressure

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K13596
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Kyushu University
• Principal Investigator: Tomoaki Kubo 九州大学, 理学研究院, 教授 (40312540)
• Co-Investigator(Kenkyū-buntansha): 加藤 工 九州大学, 理学研究院, 教授 (90214379)
• Co-Investigator(Renkei-kenkyūsha): AZUMA SHINTARO 九州大学, 大学院理学研究院, 特別研究員(PD) (60771293)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 深発地震 / 高圧変形実験 / AE測定 / 放射光実験

Outline of Final Research Achievements

Intermediate-depth earthquakes and deep moonquakes are observed at more than 2 GPa where most rocks exhibit plastic deformation rather than brittle failure, owing to high pressures and temperatures. It has been suggested that antigorite dehydration and partial melting are may be responsible for these shear instability at high pressures. In order to assess this issue, we developed an AE monitoring system for high-pressure reaction-deformation processes in large shear strains combined with Deformation-DIA apparatus and synchrotron monochromatic X-ray. We observed shear localization during the shear deformation of olivine-antigorite two-phase system. When the material was dehydrating, acoustic emissions were detected. Such shear localization and AE activities were not observed in small strains and uniaxial compression. Large shear strain may trigger shear localization and shear instability of the dehydrating material.

Free Research Field

鉱物物理