Abstract
Ice fabrics are key for understanding and predicting ice flow dynamics. Despite its importance, the characteristics and evolution of ice fabrics beyond pure and simple shear flow has largely been neglected. However, 80 % of the flow of ice in Antarctica is outside the regimes of pure and simple shear. We use a new validated numerical model (SpecCAF), which has been shown to accurately reproduce experimentally observed fabrics in both compression and simple shear, to explore the fabrics produced between pure and simple shear, as well as those that are highly rotational. We present a definitive classification of all fabric patterns. We find that intermediate deformations between pure and simple shear result in a smooth transition between a fabric characterised by a cone-shape and a secondary cluster pattern. Highly-rotational fabrics are found to produce a weak girdle fabric. In addition we obtain complete predictions for the strain required for any fabric under a 2D deformation to reach steady state at any given temperature. Use of our data in current ice flow models as well as for ice core fabric and seismic anisotropy interpretation will enhance the communities' ability to predict future ice flow in a changing climate.
Highlights
Mass loss from ice sheets is set to be the main contributor to sea-level rise this century (e.g. Shepherd et al, 2018)
If deformation regimes that have not been studied in experiments are common in the natural world, what fabrics are produced from these deformations? It is unknown how fabrics evolve at very high strains which cannot be explored in experiments
Prediction of fabric evolution is pivotal for the correct interpretation of ice core fabrics and reliably predicting ice losses in a changing climate using ice sheet modelling
Summary
Mass loss from ice sheets is set to be the main contributor to sea-level rise this century (e.g. Shepherd et al, 2018). There are a number of issues that need to be resolved before it is possible to fully interpret ice fabrics from ice cores and to be able to predict future ice flow taking ice fabric effects into account It is unknown what deformations are important in the natural world, for example the Antarctic ice-sheet. The c-axes align to produce a fabric from the combination of deformation and recrystallization. Rotational recrystallization occurs where subgrains form close to the grain boundaries due to localised stress concentrations (Drury and Urai, 1990). This acts to diffuse any concentrations of c-axis towards a particular orientation (Gödert, 2003). Rigid-body rotation acts to rotate any c-axes according to the rotational characteristics of the deformation regime the ice grains are subjected to
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