Thermal regime and slab dehydration beneath the Izu‐Bonin arc: Implications for fast and slow subduction earthquakes

  • Weiling Zhu
    State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE) Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China
  • Yingfeng Ji
    State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE) Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China
  • Rui Qu
    State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE) Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China
  • Chaodi Xie
    Department of Geophysics Yunnan University Kunming China
  • Shoichi Yoshioka
    Research Center for Urban Safety and Security, Kobe University Kobe Japan
  • Deng Zeng
    State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE) Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China

Abstract

<jats:title>Abstract</jats:title><jats:p>The transition from cold forearc to hot arc is considered fundamental to subduction dynamics. However, the range and depth of the cold nose changing significantly along the strike are difficult to constrain. By incorporating the three‐dimensional high‐resolution slab topography and MORVEL plate motion field to constrain thermomechanical modelling, we estimate the subduction thermal state and petrological dehydration in Izu‐Bonin. The multilayered hydrothermal regime gradually transitions from cold to less cold forearc, associated with a large‐scale subduction dewatering process varying along the strike. The dehydration embrittlement resulting from eclogitization and harzburgitization influences the occurrence of fast to slow earthquakes on megathrusts. Impressively, the cold nose is constrained to a depth of 60 km between the arc and Moho‐depth plate interface. The lowered temperature and delay of rock harzburgitization in the cold center of the subducted plate at depth contribute to the occurrence of deep earthquakes below the hot backarc interface.</jats:p>

Journal

  • Terra Nova

    Terra Nova 34 (2), 103-112, 2021-11-24

    Wiley

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