Ice stream motion facilitated by a shallow-deforming and accreting bed

Ice streams drain large portions of ice sheets and play a fundamental role in governing their response to atmospheric and oceanic forcing, with implications for sea-level change. The mechanisms that generate ice stream flow remain elusive. Basal sliding and/or bed deformation have been hypothesized,...

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Bibliographic Details
Published in:Nature Communications
Main Authors: Spagnolo, Matteo, Phillips, Emrys, Piotrowski, Jan A., Rea, Brice R., Clark, Chris D., Stokes, Chris R., Carr, Simon J., Ely, Jeremy C., RIBOLINI, ADRIANO, Wysota, Wojciech, Szuman, Izabela
Other Authors: Phillips, Emry, Ribolini, Adriano
Format: Article in Journal/Newspaper
Language:English
Published: 2016
Subjects:
SCALE GLACIAL LINEATIONS
WEST ANTARCTICA
FABRIC MEASUREMENTS
SUBGLACIAL BEDS
SHEET
TILL
DEFORMATION
BENEATH
MECHANICS
FLOW
West Antarctica
Antarc*
Antarctica
Online Access:http://hdl.handle.net/11568/778401
https://doi.org/10.1038/ncomms10723
https://www.nature.com/articles/ncomms10723
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Summary:Ice streams drain large portions of ice sheets and play a fundamental role in governing their response to atmospheric and oceanic forcing, with implications for sea-level change. The mechanisms that generate ice stream flow remain elusive. Basal sliding and/or bed deformation have been hypothesized, but ice stream beds are largely inaccessible. Here we present a comprehensive, multi-scale study of the internal structure of mega-scale glacial lineations (MSGLs) formed at the bed of a palaeo ice stream. Analyses were undertaken at macro- and microscales, using multiple techniques including X-ray tomography, thin sections and ground penetrating radar (GPR) acquisitions. Results reveal homogeneity in stratigraphy, kinematics, granulometry and petrography. The consistency of the physical and geological properties demonstrates a continuously accreting, shallow-deforming, bed and invariant basal conditions. This implies that ice stream basal motion on soft sediment beds during MSGL formation is accommodated by plastic deformation, facilitated by continuous sediment supply and an inefficient drainage system.

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