Preferred c-axis orientations are present in the firn at Siple Dome, West Antarctica, and recrystallization begins as shallow as 200 m depth in ice below –20°C, based on digital analysis of c-axis fabrics, grain-sizes and other characteristics of 52 vertical thin sections prepared in the field from the kilometer-long Siple Dome ice core. The shallowest section analyzed, from 22 m, shows clustering of c axes toward the vertical. By 200 m depth, girdle fabric and other features of recrystallized ice are evident in layers (or regions), separated by layers (regions) of typically finer-grained ice lacking evidence of recrystallization. Ice from about 700–780m depth, which was deposited during the last ice age, is especially fine-grained, with strongly vertical c axes, but deeper ice shows much larger crystals and strong evidence of recrystallization. Azimuthal asymmetry of some c-axis fabrics, trends in grain-size, and other indicators reveal additional information on processes and history of ice flow at Siple Dome.
|Title||Fabric and texture at Siple Dome, Antarctica|
|Authors||C. L. Diprinzio, Lawrence A. Wilen, R. B. Alley, J. J. Fitzpatrick, M. K. Spencer, A. J. Gow|
|Publication Subtype||Journal Article|
|Series Title||Journal of Glaciology|
|Record Source||USGS Publications Warehouse|
|USGS Organization||Geosciences and Environmental Change Science Center|