Ice composition evidence for the formation of basal ice from lake water beneath a cold-based Antarctic glacier
International audience Entrainment of debris by cold-based glaciers having basal temperatures as low as^17³C can be observed in the DryValleys of southVictoria Land, Antarctica.The classical models developed to explain debris incorporation at the glacier base are inappropriate in such cases, since t...
Published in: | Annals of Glaciology |
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Main Authors: | , , , |
Other Authors: | , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
1999
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Subjects: | |
Online Access: | https://hal.science/hal-03120935 https://hal.science/hal-03120935/document https://hal.science/hal-03120935/file/fichier10.pdf https://doi.org/10.3189/172756499781822011 |
Summary: | International audience Entrainment of debris by cold-based glaciers having basal temperatures as low as^17³C can be observed in the DryValleys of southVictoria Land, Antarctica.The classical models developed to explain debris incorporation at the glacier base are inappropriate in such cases, since the basal temperature is well below the freezing point. An alternative model, based on the presence of ice-marginal lakes, has recently been proposed by one of the authors (S.F.). In this model, transient wet-base conditions can occur as ice flows onto the unfrozen sediments of the lake bottom, creating conditions favorable to the entrainment of sediments and to ice accretion by water freezing. Here we describe a situation where this model is consistent with an ice-composition study of the basal part of Suess Glacier, Taylor Valley. The stable isotope composition indicates that water freezing, most probably lake water, plays a major role in the formation of the basal ice layers. Total gas content of this basal ice is considerably depleted when compared to meteoric glacier ice, in accordance with a rejection mechanism during freezing. Its gas composition, strongly enriched in CO 2 , is also indicative of the presence of a former liquid phase. |
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