<p>Forearc crust that formed at nascent subduction zones contains key evidence regarding Earth’s tectonic evolution, but its nature and underlying formation processes remain unclear. Key geological records are hidden within the deep oceanic lithosphere, highlighting the need to extract information from geophysical data by establishing clear links between rock physical properties and geological processes. Here we show that the petrophysical properties of drillcores from the Izu–Bonin arc, including forearc basalt and boninite, can be linked to the tectonic and magmatic processes experienced by these rocks. Our results indicate that the rocks which formed during forearc spreading have elevated crack densities due to intensive brittle deformation, whereas those produced by subsequent off-axis volcanism remain comparatively pristine. Petrophysics-based interpretation of the seismic velocity structure reveals that off-axis volcanic units intruded the cracked forearc crust. This provides geophysical evidence for distinct volcanic processes during nascent forearc evolution, thereby highlighting the importance of combining petrophysical and geophysical data when investigating crustal geological processes.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Cracked on-axis and pristine off-axis crust formed during forearc evolution at a nascent subduction zone

  • Yuya Akamatsu,
  • Masakazu Fujii,
  • Yumiko Harigane,
  • Tetsuya Sakuyama,
  • Yuzuru Yamamoto,
  • Nana Kamiya,
  • Katsuyoshi Michibayashi

摘要

Forearc crust that formed at nascent subduction zones contains key evidence regarding Earth’s tectonic evolution, but its nature and underlying formation processes remain unclear. Key geological records are hidden within the deep oceanic lithosphere, highlighting the need to extract information from geophysical data by establishing clear links between rock physical properties and geological processes. Here we show that the petrophysical properties of drillcores from the Izu–Bonin arc, including forearc basalt and boninite, can be linked to the tectonic and magmatic processes experienced by these rocks. Our results indicate that the rocks which formed during forearc spreading have elevated crack densities due to intensive brittle deformation, whereas those produced by subsequent off-axis volcanism remain comparatively pristine. Petrophysics-based interpretation of the seismic velocity structure reveals that off-axis volcanic units intruded the cracked forearc crust. This provides geophysical evidence for distinct volcanic processes during nascent forearc evolution, thereby highlighting the importance of combining petrophysical and geophysical data when investigating crustal geological processes.