Traveling slippery patches produce thickness-scale folds in ice sheets

Large, complex stratigraphic folds that rise as high as 60% of the local ice thickness have been observed in ice sheets on Antarctica and Greenland. Here we show that ice deformation caused by heterogeneous and time‐variable basal sliding can produce the observed structures. We do this using a therm...

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Bibliographic Details
Published in:Geophysical research letters 2014-12, Vol.41 (24), p.8895-8901
Main Authors: Wolovick, Michael J., Creyts, Timothy T., Buck, W. Roger, Bell, Robin E.
Format: Article
Language:English
Subjects:
Antarctica
basal freeze-on
basal hydrology
Columns (structural)
Deformation
Deformation mechanisms
Downstream
Feedback
Flow
Folds
Glaciation
History
Ice
ice cores
Ice cover
ice dynamics
ice sheet stratigraphy
Ice sheets
Ice thickness
Melting
Melting point
Patches (structures)
Sheets
Sliding
Slip
Slumping
Strata
Stratigraphy
Temperature
Temperature effects
Thermomechanical analysis
Travel
Velocity
Vertical flow
Vertical mixing
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Summary:Large, complex stratigraphic folds that rise as high as 60% of the local ice thickness have been observed in ice sheets on Antarctica and Greenland. Here we show that ice deformation caused by heterogeneous and time‐variable basal sliding can produce the observed structures. We do this using a thermomechanical ice sheet model in which sliding occurs when the base approaches the melting point and slippery patches develop. These slippery patches emerge and travel downstream because of a feedback between ice deformation, vertical flow, and temperature. Our model produces the largest overturned structures, comparable to observations, when the patches move at about the ice column velocity. We conclude that the history of basal slip conditions is recorded in the ice sheet strata. These basal conditions appear to be dynamic and heterogeneous even in the slow‐flowing interior regions of large ice sheets. Key Points Slippery patches beneath ice sheets propagate downstreamPropagating slippery patches create massive stratigraphic structuresThe internal structure of ice sheets is related to the history of basal slip
ISSN:0094-8276
1944-8007
DOI:10.1002/2014GL062248