Deformation-Induced Melting in the Margins of the West Antarctic Ice Streams

Abstract

Flow of glacial ice in the West Antarctic Ice Sheet localizes in narrow bands of fast-flowing ice streams bordered by ridges of nearly stagnant ice, but our understanding of the physical processes that generate this morphology is incomplete. Here we study the thermal and mechanical properties of ice-stream margins, where flow transitions from rapid to stagnant over a few kilometers. Our goal is to explore under which conditions the intense shear deformation in the margin may lead to deformation-induced melting. We propose a 2-D model that represents a cross section through the ice stream margin perpendicular to the downstream flow direction. We limit temperature to the melting point to estimate melt rates based on latent heat. Using rheology parameters as constrained by laboratory data and observations, we conclude that a zone of temperate ice is likely to form in active shear margins.