Transformation of landforms and sediments in the periglacial setting of West Greenland
The article deals with the cryogenic processes taking place in the terminal zone of the recessing glacier of SW Greenland, which modify the sediment layers and transform the landforms. The sediment horizons were examined in natural outcrops and in trenches. Structural analysis of periglacial sedimen...
| Published in: | Geologija |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | Lithuanian English |
| Published: |
2009
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| Subjects: | |
| Online Access: | http://lmavb.lvb.lt/LMAVB:ELABAPDB5832123&prefLang=en_US |
| Summary: | The article deals with the cryogenic processes taking place in the terminal zone of the recessing glacier of SW Greenland, which modify the sediment layers and transform the landforms. The sediment horizons were examined in natural outcrops and in trenches. Structural analysis of periglacial sediments in the slopes has shown that subdued evaporation and shallow permafrost favour the development of cryoturbations. In relief declensions, the formation of polygonal surfaces is predetermined by shallow beds of magmatic rocks, permafrost and especially slow evaporation during short warm seasons. Aeolian processes are most active in the valleys sculptured by glaciofluvial flows where cold arid winds blow out or rework inequigranular deposits. Dust is blown out by wind erosion, whereas the coarse-grained material is transported by creeping or saltation. Sand ripple and embryo dune terrains are widespread in glaciofluvial valleys. Wind erosion processes forming pebble-boulder deflation pavements take place in relief declensions. Outcrops sized 10-60 m2 and niches develop in the hill slopes. Diatoms indicate that sedimentation in small closed basins took place under cold, oligotrophic, acidophilous conditions. |
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