Basal topography and ice flow in the Bailey/Slessor region of East Antarctica

An airborne radio-echo sounding campaign carried out in the upper reaches of Bailey Ice Stream and Slessor Glacier, in Coats Land, East Antarctica, has revealed that tributaries of enhanced flow lie within well-defined basal troughs and are separated from each other by bed highs. These new data indicate significant differences in ice thickness compared with those estimated in the Bedmap database. A numerical modeling study has revealed that driving stresses are high enough to account for flow by ice deformation alone in intertributary areas. Most flow in the enhanced flow tributaries of Slessor Glacier may also be explained by ice deformation alone. However, although ice deformation is also significant in the Bailey Ice Stream tributary, a large amount of basal motion is also required to fully explain flow velocities here. It is proposed that the trough in which Bailey tributary lies is sufficiently deep that marine sediments may have accumulated here in preglacial times. Along with water produced by geothermal heating, frictional heating, and through a reduction in the pressure melting point, basal motion may therefore be facilitated by the presence of a deformable, saturated till layer at the bed.

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