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CRYOSTRATIGRAPHY OF NEAR-SURFACE PERMAFROST IN UNIVERSITY VALLEY, MCMURDO DRY VALLEYS OF ANTARCTICA
Session: Geocryology I / Géocryologie I
Caitlin Lapalme, University of Ottawa (Canada)
Denis Lacelle, University of Ottawa (Canada)
Alfonso Davila, Carl Sagan Center at the SETI Institute (United States)
Wayne Pollard, McGill University (Canada)
Daniel Fortier, Département de Géographie - Université de Montréal (Canada)
Christopher McKay, NASA Ames Research Center (United States)
The presence and origin of ground ice in cold and hyper-arid regions defies the conventional understanding of ground ice forming processes. This study investigates the amount, distribution and origin of ground ice in a sand-wedge polygon in University Valley, McMurdo Dry Valleys of Antarctica. Analysis of computed tomodensitometric scans revealed three types of cryostructures: structureless, suspended, and crustal. Excess ice distribution in two permafrost cores revealed greater ice content in the center of the polygon. Water isotope analysis suggests that the ground ice was emplaced by vapour deposition, similar to two nearby polygons. The higher ground ice content in the center of the polygon is likely related to the stability of the ground surface, with a less stable surface near the shoulder of the polygon as sediments fall into cracks. The results presented in this study enhance our understanding of ground ice and the processes, including environmental factors, which form the ice-cemented permafrost in cold arid regions.
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