Weak zone formation for initiating subduction from thermo-mechanical feedback of low-temperature plasticity

J. M. Branlund, K. Regenauer-Lieb, D. A. Yuen

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

We have addressed the problem of subduction initiation with a solid-mechanical and fluid-dynamical approach, using a finite-element method. The setup has been extended by a rate-sensitive coupling at the bottom of a semi-brittle lithosphere and a fully coupled thermo-mechanical model. The central element of our model is a broad asymmetric sedimentary loading function at the passive continental margin, which grows with time to 15 km. Two fundamentally different modes of shear zone formation have been found depending on the rheology of the creep layer. Mode 1: For cases of low or absent yield stress in the creep layer only, the semi-brittle top develops a weak zone, while the rate-sensitive layer acts as a decoupling shear zone. Mode 2: For cases with a yield strength in the creep layer (strain rates above 10-15 s-1 after yielding), the entire mechanical lithosphere fails on a major shear zone; mode 1 fails to model subduction initiation, while mode 2 creates a weak, major shear zone that severs through the entire lithosphere.

Original languageEnglish (US)
Pages (from-to)237-250
Number of pages14
JournalEarth and Planetary Science Letters
Volume190
Issue number3-4
DOIs
StatePublished - 2001

Bibliographical note

Funding Information:
We would like to thank Louis Moresi, Marc Parmentier and Chad Hall for a very helpful review. This work has been jointly funded by the ETH Zurich and the University of Minnesota in a project that should have become a PhD. degree of the first author. We regret that Joy preferred to finish with a Master’s degree. This is publication 1184 of the Institute of Geophysics ETH Zurich. [RV]

Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.

Keywords

  • Faults
  • Geodynamics
  • Rheology
  • Subduction
  • Thermo-mechanical properties

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