Complex fabric development revealed by englacial seismic reflectivity: Jakobshavn Isbra, Greenland

High-resolution reflection seismic data from JakobshavnIsbr, Greenland, reveal complex fabric development.Abundant englacial reflectivity occurs for approximatelyhalf the thickness of the ice (the lower half), and disruptionof the englacial reflectors occurs in the lower 1015% ofthe ice-thickness. T...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Horgan, HJ, Anandakrishnan, S, Alley, RB, Peters, LE, Tsoflias, GP, Voigt, DE, Winberry, JP
Format: Article in Journal/Newspaper
Language:English
Published: Amer Geophysical Union 2008
Subjects:
Earth Sciences
Physical Geography and Environmental Geoscience
Glaciology
Greenland
Jakobshavn
Online Access:https://doi.org/10.1029/2008GL033712
http://ecite.utas.edu.au/103896
Description
Summary:High-resolution reflection seismic data from JakobshavnIsbr, Greenland, reveal complex fabric development.Abundant englacial reflectivity occurs for approximatelyhalf the thickness of the ice (the lower half), and disruptionof the englacial reflectors occurs in the lower 1015% ofthe ice-thickness. These depths correspond to the higherimpurity-content, and more easily deformed, ice from theYounger Dryas and Last Glacial Maximum to Stage-3. Weconclude that the reflectivity results from contrastingseismic velocities due to changes in the crystal orientationfabric of the ice, and suggest that these fabric changes arecaused by variations in impurity loading and subsequentdeformation history. These findings emphasize thedifference between ice-divide and ice-stream crystalorientation fabrics and have implications for predictive icesheet modeling.

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