Open AccessA model for spiral flows in basal ice and the formation of subglacial flutes based on a Reiner‐Rivlin rheology for glacial ice
Author(s) -
Schoof Christian G.,
Clarke Garry K. C.
Publication year - 2008
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007jb004957
Subject(s) - drumlin , geology , ice stream , flute , rheology , pressure ridge , ice wedge , viscoelasticity , spiral (railway) , transverse plane , geomorphology , mechanics , sea ice , oceanography , physics , cryosphere , acoustics , anatomy , medicine , mathematical analysis , mathematics , permafrost , thermodynamics
Flutes are elongated sediment ridges formed at the base of glaciers and ice sheets. In this paper, we show that flutes can be the product of a corkscrew‐like spiral flow in basal ice that removes sediment from troughs between flutes and deposits it at their crests, as first suggested by Shaw and Freschauf. In order to generate the type of basal ice flow required for this mechanism, the viscous rheology of ice must allow for the generation of deviatoric normal stresses transverse to the main flow direction. This type of behavior, which is commonly observed in real nonlinearly viscous and viscoelastic fluids, can be described by a Reiner‐Rivlin rheology. Here, we develop a mathematical model that describes the role of these transverse stresses in generating spiral flows in basal ice and investigate how these flows lead to the amplification of initially small basal topography and the eventual formation of assemblies of evenly spaced subglacial flutes.