%0 Journal Article
%T Effects of nonlinear rheology, temperature and anisotropy on the relationship between age and depth at ice divides
%A C. Mart¨ªn
%A G. H. Gudmundsson
%J The Cryosphere Discussions
%D 2012
%I Copernicus Publications
%R 10.5194/tcd-6-2221-2012
%X Ice flow in divide areas is strongly anisotropic. The evolution of ice fabric, from the onset of divide flow towards steady-state with a fully-developed fabric, has been shown to profoundly affect both the stratigraphy and surface topography of ice divides. Here, we investigate the effects of ice flow on the age-versus-depth relationship at ice divides by using a full Stokes thermomechanical model with a non-linear anisotropic constitutive relation between stress and strain rates. We compare our results with analytical approximations commonly employed in age¨Cdepth predictions such as the Dansgaard and Lliboutry approximations. We show that these approximations systematically underestimate the age of ice at fully-developed divides by as much as one order of magnitude. We also show that divides with fully-developed fabric are ideal locations for ice-core extraction because ice under them can be up to one order of magnitude older than ice at the same depth at the flanks. In addition, these divides have a distinctive morphological structure that allows them to be clearly identified from satellite imagery or ground-penetrating radar data. Our results are particularly relevant in coastal areas of Antarctica where divides with fully-developed ice fabric are widespread.
%U http://www.the-cryosphere-discuss.net/6/2221/2012/tcd-6-2221-2012.pdf