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Rheology of the plate interface from shallow to deep subduction zone: effects of fluids and prograde metamorphism

Research Project

Project/Area Number 18H01318
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Review Section Basic Section 17040:Solid earth sciences-related
Research InstitutionJapan Agency for Marine-Earth Science and Technology

Principal Investigator

OKAZAKI Keishi  国立研究開発法人海洋研究開発機構, 超先鋭研究開発部門(高知コア研究所), 研究員 (90784257)

Project Period (FY) 2018-04-01 – 2022-03-31
Project Status Completed (Fiscal Year 2021)
Budget Amount *help
¥18,070,000 (Direct Cost: ¥13,900,000、Indirect Cost: ¥4,170,000)
Fiscal Year 2021: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2020: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2018: ¥14,300,000 (Direct Cost: ¥11,000,000、Indirect Cost: ¥3,300,000)
Keywords沈み込み帯 / 地震 / スロー地震 / レオロジー / 断層 / 岩石変形実験 / プレートテクトニクス / 岩石レオロジー / 岩石変形 / 水 / 変成岩 / 破壊 / 摩擦 / 流動 / 変成反応 / プレート境界 / 含水鉱物 / 岩石変形学 / 地殻流体
Outline of Final Research Achievements

In this study, we investigated how the rheological properties of materials existing at plate boundaries (i.e., metamorphic rocks) are changed by continuous metamorphic reactions associated with subduction using high-temperature, high-pressure rock deformation experiments. We found that the strength of the metamorphic rocks increases with the progress of metamorphism due to the decrease the amount of hydrous minerals by metamorphic reactions. On the other hand, the increase in pore fluid associated with metamorphic reactions increases the amount of water as well as the pore fluid pressure, which decreases the strength of the plate boundary. This study reveals that heterogeneity in water volume may be more responsible for the diversity of slip behavior in subduction zones than heterogeneity in pore water pressure.

Academic Significance and Societal Importance of the Research Achievements

沈み込み帯のプレート境界では、スロー地震と呼ばれる地震(1m/s)とプレート沈み込み速度(1nm/s)の中間の変形現象が起こっており、スロー地震発生域では地震波観測などにより水の存在が示唆されている。本研究でおこなった高温高圧岩石変形実験から高温高圧環境でさらに水が多量に存在するような場所では岩石が延性的に変形するだけでなく「水が並ぶ」ことにより破壊も同時に起こることがわかった。本研究からは、沈み込み帯で通常考えられている間隙水圧の不均一性よりも、水の量の不均一性の方が沈み込み帯における変形挙動の多様性をもたらしている可能性があることが示唆される。

Report

(4 results)
  • 2021 Final Research Report ( PDF )
  • 2020 Annual Research Report
  • 2019 Annual Research Report
  • 2018 Annual Research Report
  • Research Products

    (14 results)

All 2021 2020 2019 2018 Other

All Int'l Joint Research (2 results) Journal Article (3 results) (of which Int'l Joint Research: 3 results,  Peer Reviewed: 3 results,  Open Access: 1 results) Presentation (9 results) (of which Int'l Joint Research: 8 results,  Invited: 1 results)

  • [Int'l Joint Research] ブラウン大学(米国)

    • Related Report
      2019 Annual Research Report
  • [Int'l Joint Research] ブラウン大学(米国)

    • Related Report
      2018 Annual Research Report
  • [Journal Article] Rheology of the Fluid Oversaturated Fault Zones at the Brittle‐Plastic Transition2021

    • Author(s)
      Okazaki Keishi、Burdette Eric、Hirth Greg
    • Journal Title

      Journal of Geophysical Research: Solid Earth

      Volume: 126 Issue: 2

    • DOI

      10.1029/2020jb020804

    • Related Report
      2020 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Deformation of mafic schists from subducted oceanic crust at high pressure and temperature conditions2020

    • Author(s)
      Okazaki Keishi、Hirth Greg
    • Journal Title

      Tectonophysics

      Volume: 774 Pages: 228217-228217

    • DOI

      10.1016/j.tecto.2019.228217

    • Related Report
      2020 Annual Research Report 2019 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Fracture-induced pore fluid pressure weakening and dehydration of serpentinite2019

    • Author(s)
      E French Melodie、Hirth Greg、Okazaki Keishi
    • Journal Title

      Tectonophysics

      Volume: 767 Pages: 228168-228168

    • DOI

      10.1016/j.tecto.2019.228168

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Presentation] Effects of water fraction on strengths and microstructures of quartz aggregates at the brittle plastic transition2020

    • Author(s)
      Okazaki Keishi、Burdette Eric、Hirth Greg
    • Organizer
      AGU Fall Meeting 2020
    • Related Report
      2020 Annual Research Report
    • Int'l Joint Research
  • [Presentation] 剪断帯内の変形の幾何を考慮した脆性・塑性遷移域の断層構成則2020

    • Author(s)
      野田 博之, 岡崎 啓史
    • Organizer
      JpGU-AGU Joint Meeting 2020
    • Related Report
      2020 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Rheology of the fluid oversaturated simulated quartz shear zone at the brittle-ductile transition2020

    • Author(s)
      Okazaki Keishi、Burdette Eric、Hirth Greg
    • Organizer
      JpGU-AGU Joint Meeting 2020
    • Related Report
      2020 Annual Research Report
    • Int'l Joint Research
  • [Presentation] 巨大地震発生域下限の温度・圧力・間隙水圧条件を再現できる新しい固体圧岩石変形試験機の開発2020

    • Author(s)
      岡崎 啓史, 武藤 潤, 濱田 洋平, 谷川 亘, 廣瀬 丈洋
    • Organizer
      JpGU-AGU Joint Meeting 2020
    • Related Report
      2020 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Rheology of the fluid oversaturated quartz shear zone at the brittle-ductile transition2019

    • Author(s)
      Keishi Okazaki, Eric Burdette, Greg Hirth
    • Organizer
      AGU Fall Meeting 2019
    • Related Report
      2019 Annual Research Report
    • Int'l Joint Research
  • [Presentation] 半遠洋性堆積物の続成作用に伴う摩擦・透水特性の変化2019

    • Author(s)
      岡崎 啓史、片山 郁夫、山口 飛鳥
    • Organizer
      日本地球惑星科学連合2019年大会
    • Related Report
      2019 Annual Research Report
  • [Presentation] Effects of the aqueous fluid and porosity on the rheology of quartz aggregates at the brittle-plastic transition2018

    • Author(s)
      Keishi Okazaki, Eric Burdette, Greg Hirth
    • Organizer
      AGU Fall Meeting 2018 / MR23A-06
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Experimental investigation of dehydration weakening and embrittlement of hydrous minerals2018

    • Author(s)
      Keishi Okazaki
    • Organizer
      Intermediate and Deep Earthquakes: Observation and Modeling /College de France,
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Rheology of the fluid-overpressured quartz shear zone at the brittle-plastic transition: effects of the aqueous fluid and porosity2018

    • Author(s)
      Keishi Okazaki, Eric Burdette, Greg Hirth
    • Organizer
      日本地球惑星科学連合 2018年大会 / SCG53-24
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research

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Published: 2018-04-23   Modified: 2023-01-30  

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