Exhumation of (U) HP/LT rocks caused by diachronous slab breakoff

D. Boutelier, A. R. Cruden

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Abstract

Three-dimensional thermo-mechanical analogue models investigate how diachronous slab breakoff may lead to the exhumation of subducted continental crust. Slab breakoff initiates spontaneously in one location and migrates laterally along the plate boundary, causing a transient excess downward pull force on the plate boundary in front of the propagating slab tear. This pull force locally reduces the pressure between the plates, which promotes buoyancy-driven exhumation of subducted crust. However, both the surface area undergoing the pressure reduction and its duration are limited. Our experiments show that the rate of slab breakoff propagation controls both the duration of the pull force and the magnitude of pressure reduction. Our results further demonstrate that exhumation occurs where the slab breakoff propagation rate is lowest, rather than where the pull force is strongest, corresponding to where the slab tear initiates or terminates.

Original languageEnglish
Pages (from-to)251-255
Number of pages5
JournalJournal of Structural Geology
Volume117
DOIs
Publication statusPublished - 1 Dec 2018

Keywords

  • Analogue models
  • Exhumation
  • Slab breakoff
  • Subduction

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