Density Profiles and Crystal Growth Trends Observed in ITASE Cores From West Antarctica
Abstract
Results of analyses of density and crystal growth measurements in firn and ice cores recovered from the upper layers of the West Antarctic Ice Sheet during the US component of the International Trans-Antarctic Scientific Expedition (ITASE) are presented. Density profiles were measured in the field on meter-long cores; all profiles except one exhibited normal densification with respect to snow accumulation rates determined stratigraphically and with 10 m firn temperatures measured in the holes drilled for cores, or inferred from elevation changes relative to the elevation at Byrd Station (1496 m). Measurements at a single location indicated the firn had undergone extremely rapid densification to ice; the transition to ice, occurring at 35-36 m depth, is among the shallowest ever observed in the dry snow facies in Antarctica. This profile cannot be reconciled with either the mean annual temperature of the firn at this location or the snow accumulation rate measured stratigraphically. Furthermore, thin section measurements of grain size show that crystal growth at this site has occurred much more rapidly than at other locations. Accelerated growth of crystals is also observed below the firn ice transition. Such behavior, affecting both the density and crystal growth profiles at this one site, is attributed to highly localized stress in the upper layers of firn and ice. At all other locations where grain size has been measured crystal growth rates follow the same general age/temperature relationships observed by Gow in Antarctic and Greenland firn.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2002
- Bibcode:
- 2002AGUSM.A41A..01G
- Keywords:
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- 1827 Glaciology (1863)