Caracterizacao geomorfologica das areas livres de gelo em resposta da tendencia de retralao da geleira Polar Club, Peninsula Potter, Ilha Rei George, Antartica

Abstract

This study to investigate the glacial geomorphological dynamics of the ice-free areas in the Peninsula Potter, King George Island, Antarctica, in response to the recent Polar Club Glacier retreat processes. The geomorphological mapping and lacustrine systems evolution modelling between 2006-2011 were obtained with Quickbird (RGB432) image, application of the spatial digital filters in COSMO-SkyMed (cross and co-polarization, spotlight mode) images and topographic profiles visual interpretations. The methodology considered hypsometry, slope, contour and shaded relief maps of the peninsula, as. The Polar Club Glacier frontal variation between 1981-2015 was obtained with Landsat temporal analysis. The Potter Peninsula geomorphological mapping evidenced the proglacial and geomorphological processes and the spatial distribution pattern of linear marginal to ice features, as morainic ridges and glaciofluvial features, related to the contribution of the seasonal melting of snow and ice, marine terraces, ravines and rocky outcrops. The frontal glacier fluctuations modelling indicated that last glacial advance condition recorded by proglacial geomorphologic can be related Little Ice Age and continuous retreat process. Between 1981-2015 the Polar Club glacier lost 2.95km2 of total area (9.4% of total area). The retreat process can be related to the trend of rising average temperatures in recent decades, trend of increase in days with liquid precipitation in summer and the number melting degree days in last decades. The Polar Club Glacier retreat is not very significant when compared to other glaciers of King George Island, however, when observing the exposed areas was evident that there was a significant increase (36.9%). The moraine deposits evolution analysis in Peninsula Potter provided conditions for identify three phases of moraines deposition and that show past glacier front positions during periods of glacier marginal stabilization. The analysis of the evolution of lacustrine systems in the study area evidenced changes in proglacial lakes during last 34 years in response of glacial retreat dynamics.