Microstructural analysis of the NEEM ice core, Greenland by using electron backscatter diffraction (EBSD)


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Ilka.Weikusat [ at ] awi.de

Abstract

Mass loss of the Greenland ice sheet is accelerating, which is attributed to increased ice stream discharge and changes in surface mass balance including increased runoff. Ice stream discharge is caused by both ice deformation and basal sliding. For better projection of future mass loss, it is important to understand deformation mechanisms of polycrystalline ice in ice sheet. Deformation properties of polycrystalline material are related to its microstructure (e.g. crystal grain orientation and size). As recrystallization and recovery are occurring together in ice sheet, analysis of microstructure of ice is essential. Electron backscatter diffraction (EBSD) is a method for measuring crystal lattice orientation with high angular and spatial resolutions. Both c- and a-axes of ice can be measured. We analyzed Greenland NEEM ice core and the preliminary result shows that most subgrain boundaries (SGBs) observed by optical microscopy have lattice misorientations < 4°. This result is in accordance with analyses of Antarctic EDML ice core by X-ray diffractometry while it differs from threshold angle of SGB/GB estimated with a dislocation theory. The observation results from ice sheet ice could contribute to better estimations of strain rate by models based on microstructural processes.



Item Type
Conference (Poster)
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Primary Division
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Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
The Eighth Symposium on Polar Science, 04 Dec 2017 - 08 Dec 2017, NIPR, Tachikawa, Tokyo.
Eprint ID
45722
Cite as
Shigeyama, W. , Nagatsuka, N. , Homma, T. , Goto-Azuma, K. , Weikusat, I. , Drury, M. R. , Kuiper, E. J. N. , Pennock, G. M. , Mateiu, R. V. , Azuma, N. and Dahl-Jensen, D. (2017): Microstructural analysis of the NEEM ice core, Greenland by using electron backscatter diffraction (EBSD) , The Eighth Symposium on Polar Science, NIPR, Tachikawa, Tokyo, 4 December 2017 - 8 December 2017 .


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