Microstructures and Fabric Transitions of Natural Ice from the Styx Glacier, Northern Victoria Land, Antarctica

• Published in: Minerals
• Main Authors: Daeyeong Kim, David J. Prior, Yeongcheol Han, Chao Qi, Hyangsun Han, Hyeon Tae Ju
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2020
• Subjects: Ice; microstructure; crystallographic preferred orientation (CPO); Styx Glacier; electron backscatter diffraction (EBSD); Mineralogy; QE351-399.2; Victoria Land; Antarc*; Antarctica; ice core
• Online Access: https://doi.org/10.3390/min10100892; https://doaj.org/article/391909536bdb4b47b9596560153185b5

We investigated the microstructures of five ice core samples from the Styx Glacier, northern Victoria Land, Antarctica. Evidence of dynamic recrystallization was found in all samples: those at 50 m mainly by polygonization, and those at 170 m, largely by grain boundary migration. Crystallographic preferred orientations of all analyzed samples (view from the surface) typically showed a single cluster of c -axes normal to the surface. A girdle intersecting the single cluster occurs at 140–170 m with a tight cluster of a -axes normal to the girdle. We interpret the change of crystallographic preferred orientations (CPOs) at <140 m as relating to a combination of vertical compression, and shear on a horizontal plane, and the girdle CPOs at depths >140 m, as the result of horizontal extension. Based on the data obtained from the ground penetrating radar, the underlying bedrock topography of a nunatak could have generated the extensional stress regime in the study area. The results imply changeable stress regimes that may occur during burial as a result of external kinematic controls, such as an appearance of a small peak in the bedrock.