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

• 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
• Project Status: Completed (Fiscal Year 2017)
• Budget Amount: ¥3,640,000 (Direct Cost: ¥2,800,000、Indirect Cost: ¥840,000); Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2016: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2015: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
• Keywords: 深発地震 / 高圧変形実験 / AE測定 / 放射光実験 / 稍深発地震 / 脱水脆性化 / 深発月震 / 固液2相系 / 電気伝導度

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.

Research Products

• [Journal Article] D-DIA型高圧変形装置を用いたせん断変形および摩擦実験の試み (2018)
  • Author(s): 久保 友明, 岩里 拓弥, 肥後 祐司, 今村 公裕
  • Journal Title: SPring-8 Scientific Research Report Volume: in press
  • NAID: 130007969454
  • Peer Reviewed / Open Access
• [Presentation] Shear deformation experiments of two-phase aggregates of antigorite and olivine at high pressure: A preliminary study (2017)
  • Author(s): M. Ikehara, T. Kubo
  • Organizer: JpGU-AGU Joint Meeting 2017
  • Place of Presentation: 幕張メッセ
  • Year and Date: 2017-05-20
  • Int'l Joint Research
• [Presentation] Shear deformation experiments of two-phase aggregates of antigorite and olivine at high pressure: A preliminary study (2017)
  • Author(s): Mai Ikehara, Tomoaki Kubo
  • Organizer: Japan Geoscience Union meeting 2017
  • Int'l Joint Research
• [Presentation] アンチゴライトーオリビン二相系の高圧下における変形組織の観察 (2017)
  • Author(s): 池原 舞, 久保 友明
  • Organizer: 日本鉱物科学会2017年会
• [Presentation] 高圧下におけるアンチゴライトの強度と剪断不安定化 (2016)
  • Author(s): 久保友明, 岩里拓弥, 肥後祐司, 吉田雄祐, 今村公裕, 加藤工, 上原 誠一郎, 丹下慶範
  • Organizer: 日本鉱物科学会
  • Place of Presentation: 金沢大学
  • Year and Date: 2016-09-23
• [Presentation] Syndeformational dehydration experiments on antigorite and shear instability at high pressure (2016)
  • Author(s): Kubo, T., Yoshida, Y., Higo, Y., Iwasato, T., Imamura, M., Kato, T., & Tange, Y.
  • Organizer: Misasa VI “Frontiers in Earth and Planetary Materials Research: Origin, Evolution and Dynamics”
  • Place of Presentation: 三朝
  • Year and Date: 2016-03-09
  • Int'l Joint Research
• [Presentation] 高圧下における反応誘起の剪断不安定化に関する実験的研究 (2015)
  • Author(s): 久保友明, 岩里拓弥, 肥後祐司, 中田大城, 阿辺山健大, 今村公裕, 加藤工, 金嶋聰, 上原誠一郎, 丹下慶範
  • Organizer: 日本鉱物科学会2015年会
  • Place of Presentation: 東京
  • Year and Date: 2015-09-27