Using electron backscatter diffraction to measure full crystallographic orientation in Antarctic land-fast sea ice

We have mapped the full crystallographic orientation of sea ice using electron backscatter diffraction (EBSD). This is the first time EBSD has been used to study sea ice. Platelet ice is a feature of sea ice near ice shelves. Ice crystals accumulate as an unconsolidated sub-ice platelet layer beneat...

Full description

Bibliographic Details
Published in:Journal of Glaciology
Main Authors: PAT WONGPAN, DAVID J. PRIOR, PATRICIA J. LANGHORNE, KATHERINE LILLY, INGA J. SMITH
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press 2018
Subjects:
crystal growth
glaciological instruments and methods
ice crystal studies
sea ice–ice shelf interactions
Environmental sciences
GE1-350
Meteorology. Climatology
QC851-999
Antarctic
Antarc*
Ice Shelf
Ice Shelves
Journal of Glaciology
Sea ice
Online Access:https://doi.org/10.1017/jog.2018.67
https://doaj.org/article/f21b92d62fdc42118a6a8c9190f3f6e7
Description
Summary:We have mapped the full crystallographic orientation of sea ice using electron backscatter diffraction (EBSD). This is the first time EBSD has been used to study sea ice. Platelet ice is a feature of sea ice near ice shelves. Ice crystals accumulate as an unconsolidated sub-ice platelet layer beneath the columnar ice (CI), where they are subsumed by the advancing sea–ice interface to form incorporated platelet ice (PI). As is well known, in CI the crystal preferred orientation comprises dominantly horizontal c-axes, while PI has c-axes varying between horizontal and vertical. For the first time, this study shows the a-axes of CI and PI are not random. Misorientation analysis has been used to illuminate the possible drivers of these alignments. In CI the misorientation angle distribution from random pairs and neighbour pairs of grains are indistinguishable, indicating the distributions are a consequence of crystal preferred orientation. Geometric selection during growth will develop the a-axis alignment in CI if ice growth in water is fastest parallel to the a-axis, as has previously been hypothesised. In contrast, in PI random-pair and neighbour-pair misorientation distributions are significantly different, suggesting mechanical rotation of crystals at grain boundaries as the most likely explanation.

Similar Items