GLACIAL LANDFORMS AND WEATHERING PROCESSES IN THE BALCHENFJELLA REGION, EASTERN PART OF THE SOR RONDANE MOUNTAINS, EAST ANTARCTICA

摘要

Glacial landforms and weathering processes have been investigated in the Balchenfjella region, eastern part of the Sor Rondane Mountains, East Antarctica. This region had entirely been covered with the former ice sheet, and shows less alpine features in comparison with the other parts of the Sor Rondane. Deglaciation occurred at first in the northern region, Vesthjelmen-Austharmaren area. Succeedingly, the southern part of South Balchenfjella and the mountain tops in the Bulken-Hesteskoen area became free from ice. North Balchenfjella emerged in the latest stage of deglaciation. Around the areas from Bulken to South Balchenfjella, different stage of deglaciation was probably due to the ice step which had been formed by damming of ice flow by the mountainu27s threshold. The step still remains behind the South Balchenfjella area. Shattering and granular disintegration are most predominant among weathering features in this region. Salt aggregations, mostly gypsum, are observed in any locality. Beautifully crystallized gypsum was predominantly found in the North Balchenfjella area. Desert varnish was also examined. Chemical analysis clearly defined that the desert varnish is a film composed of crystalline jarosite mixed with amorphous silica. The varnish coat is formed by a solution of sulfuric acid from the underlying ground. Capirally action is effective for this solution to ascend through very narrow cracks within a rock.