Compacted Snow Dune Complexes in Antarctica and their Applicability as New Climate Change and Basement Tectonic Parameters

Abstract

AbstractCompacted snow dunes were described for the first time as long stripes by pilots flying over eastern Antarctica. With the availability of satellite imagery, the interest has increased manifolds. Later Synthetic Aperture Radar (SAR) data provided nearly three-dimensional, enhanced relief pictures, of these dune complexes. Divergent views regarding their formation have been presented earlier. One group believed that they are erosional features imprinted on ice sheets due to strong katabatic winds, while the other one suggested that they have formed due to the accumulation of snow. Our interpretation of SAR and optical images over an area of 1,000,000 sq. km, suggests that they are a type of “fore-dunes”, characterized by gentle wind-ward and steeper lee-ward sides. Deposited and compacted during intense climatic conditions. We believe that alternating wet and arid conditions prevailed during their formation and compaction. Wet periods were dominated by moisture-laden, low amplitude and long wavelength winds. This was accompanied by very heavy snowfall and accumulation as linear ridges perpendicular to the wind direction. Arid periods were marked by dry winds, compaction and development of wide-spread glazed surfaces on the lee-ward sides. Similarly, during the following period, with slightly less intense climatic conditions, snow sheets were deposited. Pile-ups along the high-rise regions later consolidated as ridges (sastrugi). These prominent climatic variations of continental proportions are mapped and seem to correspond with glacial and interglacial periods of the Quaternary Era. Prevailing as well as paleo-wind directions coincide with each other this indicates that there has been no marked change ever since they have formed. Furthermore, abrupt termination and shifting of compacted dunes, and formation of elongated valleys, filled by consolidated snow along parallel set of lineaments, are mapped in all the studied regions. This suggests that the lineaments are of basement origin and have propagated upward through the cover of ice and snow. We believe that the compacted snow dunes complexes and lineaments are unique markers and can serve as new parameters, to understand climatic changes and basement configuration of Antarctic continent.KeywordsSnow dunesSnow sheetsClimate changeLineamentsBasement tectonicsRadar imagesAntarctica