EBSD in Antarctic and Greenland Ice
Other literature type
Kuiper, Ernst-Jan N.
Pennock, Gill M.
Drury, Martyn R.
(issn: 1869-9529, eissn: 1869-9529)
EBSD provides information for the characterization of subgrain boundary types and dislocation activity during deformation. EBSD microstructure in combination with light microscopy measurements from ice core material from Antarctica (EPICA-DML deep ice core) and Greenland (NEEM deep ice core) are presented and interpreted regarding substructure identification and characterization. Electron backscattered diffraction (EBSD) analyses suggest that a large portion of edge dislocations with slip systems basal <a> gliding on the basal plane were involved in forming subgrain boundaries. However, an almost equal number of tilt subgrain boundaries developed, involving dislocations gliding on non basal planes (prism <c> or prism <c+a> slip). A few subgrain boundaries involving prism <a> edge dislocation glide, as well as boundaries involving basal <a> twist dislocations, were also identified. The finding that subgrain boundaries occur, made
up of dislocations gliding on non-basal planes, are as frequent as basal plane slip systems, is surprising. These findings are expected to have an impact on the discussion of rate-controlling processes for the ice flow descriptions of large ice masses with respect to sea-level evolution. For subgrain boundaries not related to the crystallography of the host grain alternative formation processes are discussed.