Ice dynamical studies in the Sør Rondane mobottom inuntains, Dronning Maud Land, East Antarctica
Pattyn, F.; Decleir, H.; Huybrechts, P. (1993). Ice dynamical studies in the Sør Rondane mobottom inuntains, Dronning Maud Land, East Antarctica, in: Caschetto, S. (Ed.) Belgian scientific research programme on Antarctica: scientific results of phase II (10/1988-05/1992): 3. Glaciology and climatology. pp. II/04/B/1-35
In: Caschetto, S. (Ed.) (1993). Belgian scientific research programme on Antarctica: scientific results of phase II (10/1988-05/1992): 3. Glaciology and climatology. Belgian scientific research programme on Antarctica. Belgian Science Policy Office: Brussel. 259 pp., meer
In: Belgian scientific research programme on Antarctica. Belgian Science Policy Office: Brussel. , meer
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| Abstract |
On the basis of field work carried out during three antarctic summer seasons, -in collaboration with the Japanese Antarctic Research Expedition (JARE)-, and by means of both Landsat TM and SPOT satellite imagery , we present a quantitative and qualitative picture of the glacier characteristics and subglacial relief of the Central Part of the Sør Rondane area, Dronning Maud Land, Antarctica. The quantitative data are then used in a model to simulate both the present and the past glacier behaviour. For this purpose we describe first the mass balance and temperature regime of the area as a function of elevation. The mass balance is derived from previous Belgian work in the same area, while the temperature regime was taken fiom a parameterization of Fortuin and Oerlemans. Arguments to use this parameterization was found by studying the brightness temperatures of the snow surface (from Landsat TM thermal red band) which displays also a twofold temperature gradient as found by these authors. The map of ice surface characteristics, based on field work and on an interpretation of a colour composite, combining SPOT channels XSI, SXS2 and XS3, allows a distinction to be made between active and passive glaciers and to identify the upper region of the Sør Rondane area as en ablation island. On the basis of movement stakes, surveyed during two consecutive seasons, the velocity field and dynamical aspects of Jenningsbreen could be determined. It was shown how this glacier is in the process of being cutoff from the main ice supply. The resulting negative divergence of the horizontal velocity field explains the vertical movement necessary for the emergence at the glacier surface of englacial debris to form the extensive supraglacial tills. Ice thickness measurements were carried out using the radio echo sounding and gravimeter technique during three field seasons. The results are presented as rnaps of subglacial relief, revealing the central part of the Sør Rondane as an ice covered fjord landscape. The characteristic U-shaped valley cross-profiles originated by widening and deepening of an inherited coastal mountain fluvial drainage pattem. A flow line model was then developed to simulate the behaviour of the outletglaciers of the Sør Rondane. The nearly stagnant character of Jenningsbreen was confirmed. It is shown how the present ablational character of the Sør Rondane is in equilibrium with the glacier dynarnics. A significant greater ablation is required to produce deglaciation in this area. The simulation of the Last Glacial Maximum shows a very modest increase in elevation and advancement of the ice sheet. In the mountains this explains a 200-400 m ice surface increase. Glacio-geological findings, which refer to a higher glacier stand, must then be brought back to events prior to the LOM and witness much wetter, probably Late Cenozoic, environmental conditions. |
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