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Complex fabric development revealed by englacial seismic reflectivity: Jakobshavn Isbræ, Greenland
Author(s) -
Horgan H. J.,
Anandakrishnan S.,
Alley R. B.,
Peters L. E.,
Tsoflias G. P.,
Voigt D. E.,
Winberry J. P.
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl033712
Subject(s) - geology , ice sheet , reflection (computer programming) , younger dryas , reflectivity , glacial period , geomorphology , mineralogy , optics , physics , computer science , programming language
High‐resolution reflection seismic data from Jakobshavn Isbræ, Greenland, reveal complex fabric development. Abundant englacial reflectivity occurs for approximately half the thickness of the ice (the lower half), and disruption of the englacial reflectors occurs in the lower 10–15% of the ice‐thickness. These depths correspond to the higher impurity‐content, and more easily deformed, ice from the Younger Dryas and Last Glacial Maximum to Stage‐3. We conclude that the reflectivity results from contrasting seismic velocities due to changes in the crystal orientation fabric of the ice, and suggest that these fabric changes are caused by variations in impurity loading and subsequent deformation history. These findings emphasize the difference between ice‐divide and ice‐stream crystal orientation fabrics and have implications for predictive ice sheet modeling.