Fabric and Texture at Siple Dome

DI PRINZIO, CARLOS LEONARDO; WILEN L. A.

JOURNAL OF GLACIOLOGY

Año: 2005 vol. 51 p. 1 - 10

0022-1430

Preferred c-axis orientations are developed in the firn at SipleDome, West Antarctica, and recrystallization begins as shallow as 200 m depthin ice below -20°C, based on digital analysis of c-axis fabrics, grain sizes, andother characteristics of 52 vertical thin sections prepared in the field from thekilometer-long Siple Dome ice core. The shallowest section analyzed, from 22m, shows clustering of c-axes toward the vertical. By 200 m depth, the girdlefabrics and other features of recrystallized ice are evident in layers or regions,separated by layers or regions of typically finer-grained ice lacking evidence ofrecrystallization. Ice from about 700-780 m depth, which was deposited duringthe ice age, is especially fine-grained with strongly vertical c-axes, but deeperice shows much larger crystals and strong evidence of recrystallization.Azimuthal asymmetry of some c-axis fabrics, trends in grain size, and otherindicators reveal additional information on processes and history of ice flow atSiple Dome.