Using Electron Backscatter Diffraction Patterns to Examine Recrystallization in Polar Ice Sheets

• Published in: Journal of Glaciology
• Main Authors: Obbard, Rachel, Baker, Ian, Sieg, Katherine
• Format: Text
• Language: unknown
• Published: Dartmouth Digital Commons 2006
• Subjects: textures; high angle grain boundary; reorientation; polygonization; grain growth; electron backscattering; electron diffraction; diffraction pattern; recrystallization; crystal orientation; microstructures; polycrystalline ice; ice sheets; polar region; ice caps; greenland; polar regions; arctic region; texture; Earth Sciences; Glaciology; Physical Sciences and Mathematics; Arctic; Greenland; Greenland Ice Sheet Project; Ice Sheet
• Online Access: https://digitalcommons.dartmouth.edu/facoa/3528; https://doi.org/10.3189/172756506781828458; https://digitalcommons.dartmouth.edu/context/facoa/article/4517/viewcontent/div_class_title_using_electron_backscatter_diffraction_patterns_to_examine_recrystallization_in_polar_ice_sheets_div.pdf

The fabric of polycrystalline ice is typically described using the c-axis orientation alone, but this is insufficient for a full description of grain orientations in this hexagonal material. Electron backscatter diffraction (EBSD) provides full c- and a-axis orientation of individual grains, and is used here to study Greenland Ice Sheet Project 2 (GISP2) ice specimens from depths of 1551, 1642 and 1745 m. Complete orientation data are used to compare nearest-neighbor relationships to overall fabric and to differentiate between recrystallization mechanisms. Changes in orientation between grains and subgrains in GISP2 specimens were correlated with the appearance of grain boundaries on thin sections and used to identify grain sets that were probably produced by polygonization. Comparison of grain misorientations that take into account both c- and a-axis differences with those derived from c-axis directions alone reveals the presence of polygonization and illustrates the usefulness of this technique.