Large-scale ice flow over a viscous basal sediment: Theory and application to ice stream B, Antarctica

摘要: Recent seismic studies of ice stream B, Antarctica and field analysis mid-latitude glacial deposits suggest that deformable basal sediments (e.g., water-saturated till) are important in determining sheet flow. If the ratio till viscosity to effective is small, vertical shear associated with horizontal flow confined deforming bed alone. Ice over a thus akin floating shelves, because shelves inviscid seawater. For some Antarctic streams, possibly for portions late Wisconsin sheets North America Eurasia, drag sediment does not induce significant gradients velocity. Instead, affects as if it were body force balanced by longitudinal transverse deviatoric stress gradients. Comparison observed B finite element simulations incorporating viscous simple theology sufficient explain current velocity profile. These also highlight importance regions where driving do locally balance. While deformation critical existence, sensitivity tests shelf back pressure still crucial control affecting response atmospheric oceanic climate.