Generation and movement of subglacial water beneath Dome A, Antarctica (Invited)
Abstract
Recent results from the AGAP aereogeophysical survey (~250 x 750 km) resolve a richly detailed bed in the interior of the East Antarctic Ice Sheet near Dome A (80o22’S 77o22’E). The underlying Gamburtsev Mountains have a largely north-south trend with large trunk valleys, smaller tributary valleys, and steep valley heads. Ice thickness in deep valleys is approximately 3000 m and and over twice that of ice on mountain ridges. In the valleys, ice melts to form subglacial hydrologic networks. Because the valley network predates the present state of the ice sheet, flow of ice is not necessarily codirectional with down valley orientation. In some cases, the ice sheet flows up a valley rather than down, as is typical of alpine glaciers. Water flow is then up the valleys as it flows down the present-day subglacial hydraulic potential. Freezing occurs as water flows to higher subglacial elevations and can account for as much as 30% of the thickness of the ice sheet. Water freezes either as result of enhanced heat conduction through thinner ice or possibly through glaciohydraulic supercooling along steep subglacial slopes. This handshaking of topography, heat flow, and ice flow creates a wonderful example of water generation and flow that ceases where refreezing occurs. In this paper, we discuss the AGAP aereogeophysical survey, identification of water beneath the ice, models of water flow and refreezing, and the newly discovered accretion ice. We conclude by discussing how our data and interpretations affect understanding of other areas of the ice sheets as well as the search for oldest ice in the interior of Antarctica.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.C14A..06C
- Keywords:
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- 0726 CRYOSPHERE / Ice sheets;
- 0794 CRYOSPHERE / Instruments and techniques;
- 0798 CRYOSPHERE / Modeling;
- 0999 EXPLORATION GEOPHYSICS / General or miscellaneous