Emergent anisotropy and flow alignment in viscous rock

Muhlhaus, H. B., Moresi, L. and Cada, M. (2004) Emergent anisotropy and flow alignment in viscous rock. Pure and Applied Geophysics, 161 11-12: 2451-2463.


Author Muhlhaus, H. B.
Moresi, L.
Cada, M.
Title Emergent anisotropy and flow alignment in viscous rock
Journal name Pure and Applied Geophysics   Check publisher's open access policy
ISSN 0033-4553
1420-9136
Publication date 2004-12
Sub-type Article (original research)
DOI 10.1007/s00024-004-2575-5
Volume 161
Issue 11-12
Start page 2451
End page 2463
Total pages 13
Place of publication Basel, Switzerland
Publisher Birkhauser Verlag
Collection year 2004
Language eng
Subject C1
260206 Earthquake Seismology
780104 Earth sciences
CX
Abstract A novel class of nonlinear, visco-elastic rheologies has recently been developed by MUHLHAUS et al. (2002a, b). The theory was originally developed for the simulation of large deformation processes including folding and kinking in multi-layered visco-elastic rock. The orientation of the layer surfaces or slip planes in the context of crystallographic slip is determined by the normal vector the so-called director of these surfaces. Here the model (MUHLHAUS et al., 2002a, b) is generalized to include thermal effects; it is shown that in 2-D steady states the director is given by the gradient of the flow potential. The model is applied to anisotropic simple shear where the directors are initially parallel to the shear direction. The relative effects of textural hardening and thermal softening are demonstrated. We then turn to natural convection and compare the time evolution and approximately steady states of isotropic and anisotropic convection for a Rayleigh number Ra=5.64x10(5) for aspect ratios of the experimental domain of 1 and 2, respectively. The isotropic case has a simple steady-state solution, whereas in the orthotropic convection model patterns evolve continuously in the core of the convection cell, which makes only a near-steady condition possible. This near-steady state condition shows well aligned boundary layers, and the number of convection cells which develop appears to be reduced in the orthotropic case. At the moderate Rayleigh numbers explored here we found only minor influences in the change from aspect ratio one to two in the model domain.
Keyword Geochemistry & Geophysics
Wave-form Inversion
Upper-mantle
Rayleigh
Convection
Existence
Viscosity
Rheology
Layers
Zone
Love
Q-Index Code C1

 
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Created: Wed, 15 Aug 2007, 05:09:33 EST