Microstructural evolution in the fine-grained region of the Siple Dome (Antarctica) ice core
Abstract:An in-depth analysis of seven samples from the Siple Dome (Antarctica) ice core, using optical microscopy and electron backscatter diffraction, illustrates rotational recrystallization or polygonization in the fine-grained region of the core between 700 and 800 m. Between 640 and 700 m, the microstructure is characterized by a bimodal grain-size distribution and a broken girdle fabric with evidence of polygonization. From 727 to 770 m, mean grain size decreases and a single-maximum fabric is found, and, by 790 m, mean grain size has again increased and a multiple-maxima fabric manifests itself. We compare grain-size distribution, c- and a-axis orientation, and misorientation between adjacent grains. We found that misorientations between adjacent grains in the 727–770 m region were predominantly low-angle and typically around a common a-axis, suggesting polygonization. This conclusion is supported by radar evidence of a physical disturbance at 757 m, which may be correlated with higher than usual strain in the 700–800 m range. Below 770 m, larger less regular misorientations and textural evidence show that migration recrystallization is the primary recrystallization mechanism.
Document Type: Research Article
Publication date: December 1, 2011
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- The Journal of Glaciology is published six times per year. It accepts submissions from any discipline related to the study of snow and ice. All articles are peer reviewed. The Journal is included in the ISI Science Citation Index.
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