Deformation with coupled chemical diffusion

Klaus Regenauer-Lieb, Bruce Hobbs*, Alison Ord, Oliver Gaede, Ron Vernon

*Corresponding author for this work

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

The deformation of rocks is commonly intimately associated with metamorphic reactions. This paper is a step towards understanding the behaviour of fully coupled, deforming, chemically reacting systems by considering a simple example of the problem comprising a single layer system with elastic-power law viscous constitutive behaviour where the deformation is controlled by the diffusion of a single chemical component that is produced during a metamorphic reaction. Analysis of the problem using the principles of non-equilibrium thermodynamics allows the energy dissipated by the chemical reaction-diffusion processes to be coupled with the energy dissipated during deformation of the layers. This leads to strain-rate softening behaviour and the resultant development of localised deformation which in turn nucleates buckles in the layer. All such diffusion processes, in leading to Herring-Nabarro, Coble or "pressure solution" behaviour, are capable of producing mechanical weakening through the development of a "chemical viscosity", with the potential for instability in the deformation. For geologically realistic strain rates these chemical feed-back instabilities occur at the centimetre to micron scales, and so produce structures at these scales, as opposed to thermal feed-back instabilities that become important at the 100-1000 m scales.

Original languageEnglish
Pages (from-to)43-54
Number of pages12
JournalPhysics of the Earth and Planetary Interiors
Volume172
Issue number1-2
DOIs
Publication statusPublished - Jan 2009

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