Dynamical mechanisms controlling formation and avalnche of a stagnant slab

Physics of the Earth and Planetary Interiors Volume 183 Issue 1-2 Page 309-320 published_at 2010-11
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Title ( eng )
Dynamical mechanisms controlling formation and avalnche of a stagnant slab
Creator
Tagawa Michio
Iwase Yasuyuki
Source Title
Physics of the Earth and Planetary Interiors
Volume 183
Issue 1-2
Start Page 309
End Page 320
Abstract
We performed a numerical study to understand the dynamical mechanism controlling the formation and avalanche of a stagnant slab using two-dimensional dynamical models of the integrated plate-mantle system with freely movable subducting and overriding plates. We examined slab rheology as a mechanism for producing various styles of stagnating or penetrating slabs that interact with the 410-km and 660-km phase transitions. The simulated results with the systematically changed rheological parameters are interpreted using a simple stability analysis that includes the forces acting on the stagnant slab. Slab plasticity that memorizes the shape produced by past deformation generates slab stagnation at various depths around the 660-km phase transition. The slab stagnates even beneath the 660-km phase boundary, with a gentle Clapeyron slope. Feedbacks between trench backward migration and slab deformation promote each other during the slab stagnation stage. Slab viscosity also determines the final state of the subducted slab, that is, it continues stagnation or initiates penetration. A low viscosity slab can finally penetrate into the lower mantle because the growth time of the Rayleigh–Taylor instability is shorter. After the avalanche, the direction of the trench migration changes depending on the lower mantle slab viscosity.
Keywords
Stagnant slab
Subduction
Mantle convection
Rheology
Numerical modeling
NDC
Earth sciences. Geology [ 450 ]
Language
eng
Resource Type journal article
Publisher
Elsevier Science BV
Date of Issued 2010-11
Rights
Copyright (c) 2010 Published by Elsevier B.V.
Publish Type Author’s Original
Access Rights open access
Source Identifier
[ISSN] 0031-9201
[DOI] 10.1016/j.pepi.2010.02.003
[NCID] AA00773963
[DOI] http://dx.doi.org/10.1016/j.pepi.2010.02.003