Generation of tectonic over-pressure inside subducting oceanic lithosphere involving phase-loop of olivine-wadsleyite transition

Byung-Dal So, David A Yuen

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11 Citations (Scopus)

Abstract

We conducted a two-dimensional numerical model to analyze the generation of tectonic over-pressure, which is a positive deviation from lithostatic pressure, for deep slabs which are anchored at the 660 km phase boundary. The formation of the ductile shear zone under a compressional tectonic setting induces tectonic over-pressure. We first propose that an apparent shear zone originated from an elastic heterogeneity in the phase loop, which is the two-phase (i.e., olivine and wadsleyite) coexistence interval around the 410 km boundary within subducting oceanic lithospheres, can cause tectonic over-pressure with a range from 0.3 to 1.5 GPa. This over-pressure significantly impacts the formation of the olivine-wadsleyite phase transition. The flattening of the olivine-wadsleyite interface by over-pressure is well-resolved. Therefore, we argue that the over-pressure should be applied when analyzing the phase boundary within the subducting lithosphere. Our results provide a new insight on the interplay among the phase transition, shear zone formation and tectonic over-pressure.
Original languageEnglish
Pages (from-to)59-69
Number of pages11
JournalEarth and Planetary Science Letters
Volume413
DOIs
Publication statusPublished - 2015

Keywords

  • Olivine-spinel coexistence zone
  • Phase loop
  • Phase transition
  • Shear heating
  • Subducting slab
  • Tectonic over-pressure

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