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A area exposta a frente de geleiras em retracao sofre processos de retrabalhamento pela acao do vento, variacao da temperatura e agua liquida. Diante disso, o presente trabalho investigou o retrabalhamento de sedimentos em bacias de drenagem proglaciais e periglaciais e possiveis mudancas no relevo na peninsula Fildes, ilha Rei George, Antartica. Foram analisadas a granulometria e morfoscopia de 11 amostras sedimentares coletadas em diferentes transectos em area proglacial da geleira e em duas areas periglaciais. As amostras proximais a geleira mostram pouco retrabalhamento, predominando cascalhos, sedimentos angulosos e sem estrias. Os lagos e canais glaciofluviais nessa bacia de drenagem atuam na selecao do material encontrado a jusante, predominando areia, material subangular a arredondado e esfericidade media. Na area periglacial, na bacia do rio do Vento, predomina cascalho e material sedimentar anguloso nos setores a montante, evidenciando intemperismo fisico; a jusante predomina areia e material arredondado e com alta esfericidade. Na bacia do rio Grande evidencia-se a presenca de areia, material menos anguloso e mais esferico. Diante disso, se a geleira Collins continuar retraindo como nas ultimas decadas, podera haver maior retrabalhamento dos sedimentos pelo fluxo de agua na zona proglacial. Para as duas bacias periglaciais, um aumento de temperatura do ar pode ocasionar maior quantidade de agua de fusao da neve. Podem ocorrer mudancas ambientais como rebaixamento do relevo pela erosao e preenchimento das bacias por sedimentos provenientes das paredes das falesias e tambem transportados por canais de fusao da neve. A B S T R A C T The exposed area ahead of shrinking glaciers undergoes reworking processes by wind, temperature variation and liquid water action. Therefore, the present work investigated the reworking of sediments in proglacial and periglacial drainage basins and possible changes in the relief on the peninsula Fildes, King George Island, Antarctica. The granulometry and morphoscopy of 11 sedimentary samples collected in different transects, in the proglacial area and in two periglacial areas, were analyzed. The granulometry was  performed for the determination of the material textural and a morphoscopic analysis to obtain the roundness and sphericity index. The sediments proximal to the glacier show little reworking, predominating gravels, angular sediments and without striae. The lakes and glaciofluvial channels in this drainage basin act in the selection of the material found downstream, predominating sand, rounded subangular material and medium sphericity. In the periglacial area, in the Rio do Vento basin, gravel and angular sedimentary material predominate in upstream sectors, evidencing physical weathering; downstream sand and rounded material with high sphericity predominance. In the Rio Grande basin there is evidence of sand, less angular and more spherical material. In view of this, if the Collins glacier continues to retract as in the last decades, there may be greater reworking of sediments by the flow of water in the proglacial zone. For the two periglacial basins, an increase in the air temperature can cause a greater amount of snow melting water. There may be environmental changes such as lowering the relief by erosion and filling the basins with sediments from the walls of the cliffs and also transported by snow melting channels. Keywords: glaciology; glacial basins; environmental changes.

revista brasileira de geografia física

Retrabalhamento de Sedimentos em Bacias Glaciais da Península Fildes, Antártica (Reworking of Sediments in Glacial Basins of The Fildes Peninsula, Antarctica)