The microstructure of polycrystalline ice, such as that found in a glacier, is defined by its texture (size and shape of the crystals) and fabric (the overall orientation of the crystals). Ice crystals grow, rotate, and recrystallize with time and stress. The rate at which each of these processes occur depends on the temperature, the impurity content of the ice, and on the stress exerted by overburden and glacier flow.
Collaborative Research: VeLveT Ice - eVoLution of Fabric and Texture in Ice at WAIS Divide, West Antarctica
NSF Office of Polar Programs Grant 1142035
VeLveT Ice is a comprehensive study of the relationship between ice microstructure, impurities, and ice flow and their connection to climate history for the West Antarctic Ice Sheet (WAIS) Divide ice core site. Many scientists have observed that the microstructure of ice evolves with depth and time in an ice sheet. This evolution of microstructure depends on the ice flow field, temperature, and impurity content. The flow field, in turn, depends on glacier microstructure, leading to feedbacks that produce layered variations in microstructure that are related to climate and flow history. Our objective is to understand how the evolution of microstructure with time and stress in the West Antarctic ice sheet is related to impurity content, temperature, and strain rate and how the spatial variability of microstructure and its effect on ice flow affects our interpretation of climate history in the WAIS Divide ice core. This project combines a detailed study of ice crystal orientation fabrics obtained through scanning electron microscope based Electron Backscatter Diffraction (EBSD) with measurements of borehole deformation made using logging instruments. We will incorporate and build on data collected by related WAIS Divide projects, including borehole sonic velocity measurements, borehole optical dust log measurements, borehole temperature, crystal size and shape, and ice core chemistry.
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