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Journal of Glaciology 57, 205 (2011) 942-948
Competition between grain growth and grain-size reduction in polar ice
J. Roessiger 1, P. D. Bons 1, A. Griera 2, M. W. Jessell 3, L. Evans 4, M. Montagnat 5, S. Kipfstuhl 6, S. Faria 7, I. Weikusat 6
(01/10/2011)

Static (or 'normal') grain growth, i.e. grain boundary migration driven solely by grain boundary energy, is considered to be an important process in polar ice. Many ice-core studies report a continual increase in average grain size with depth in the upper hundreds of metres of ice sheets, while at deeper levels grain size appears to reach a steady state as a consequence of a balance between grain growth and grain-size reduction by dynamic recrystallization. The growth factor k in the normal grain growth law is important for any process where grain growth plays a role, and it is normally assumed to be a temperature-dependent material property. Here we show, using numerical simulations with the program Elle, that the factor k also incorporates the effect of the microstructure on grain growth. For example, a change in grain-size distribution from normal to log-normal in a thin section is found to correspond to an increase in k by a factor of 3.5.
1 :  Institut fur Geowissenschaften
Eberhard Karls Universität
2 :  Departament de Geologia
Universitat Autónoma de Barcelona
3 :  Laboratoire des Mécanismes et Transfert en Géologie (LMTG)
CNRS : UMR5563 – Observatoire Midi-Pyrénées – Université Paul Sabatier (UPS) - Toulouse III – Institut de recherche pour le développement [IRD] : UMR154
4 :  Australian Crustal Research Centre, School of Geosciences, Monash University
Monash University
5 :  Laboratoire de glaciologie et géophysique de l'environnement (LGGE)
CNRS : UMR5183 – OSUG – INSU – Université Joseph Fourier - Grenoble I
6 :  Alfred-Wegener-Institut für Polar- und Meeresforschung
Alfred-Wegener-Institut für Polar- und Meeresforschung
7 :  Universität Göttingen (GZG)
Universität Göttingen - Geowissenschaftliches Zentrum der Universität Göttingen
EDGE
Planète et Univers/Sciences de la Terre/Géomorphologie