Title Deglaciation sedimentologic and geomorphologic features of the Wanda and Ecology glaciers, King George Island, Antarctica [Feicoes sedimentologicas e geomorfologicas do ambiente de deglaciacao das geleiras Wanda e Ecology, ilha Rei George, Antartica]
Author da Rosa, K.K.; Vieira, R.; Ferrando, F.J.; Simoes, J.C.
Author Affil da Rosa, K.K., Universidade Federal do Rio Grande do Sul, Instituto de Geociencias, Porto Alegre, Brazil. Other: Universidad de Chile, Chile
Source Pesquisas em Geociencias, 36(3), p.315- 326, . Publisher: Universidade Federal do Rio Grande do Sul, Instituto de Geociencias, Porto Alegre, Brazil. ISSN: 1518- 2398
Publication Date 2009
Notes In Portuguese with English summary. 19 refs. Ant. Acc. No: 91379. GeoRef Acc. No: 309698
Index Terms geomorphology; glacial geology; glaciers; remote sensing; sediments; striations; Antarctica--Admiralty Bay; Antarctica--King George Island; Admiralty Bay; Antarctica; bedding plane irregularities; clastic sediments; deglaciation; Ecology Glacier; eskers; flute casts; fluvial features; glacial features; granulometry; kames; King George Island; moraines; satellite methods; Scotia Sea Islands; sedimentary structures; sedimentology; South Shetland Islands; SPOT; Wanda Glacier
Abstract A comparative study of changes at deglaciation environments was carried out at Wanda and Ecology glaciers, King George Island, Antarctica, by examining erosion and depositional processes. Data for the reconstruction of deglaciation were based on geomorphological and aerial photograph interpretations, as well as on analysis of multi-year spot satellite images. Subglacial processes were investigated by means of morphoscopic and granulometric analyses of sediments collected during the summer season, and co-variance between Ra (percentage of angular clasts) and C40 (percentage of clast radio c/a <=0.4) indexes. These glaciers have been retreating rapidly since 1956, with no periods of expansion. However, it is possible to observe differences in both glaciers deglaciation processes. The Ecology glacier has lost 1.35 km2, whereas the Wanda glacier only 0.64 km2 in five decades. The retreat of the Ecology glacier has been greater at the northern part of the proglacial zone; a low frontal moraine at the southern part indicates a recent glacier ice front stabilization. In the Wanda glacier, ice flow orientation has changed during different retreat phases, together with with ice thickness decrease. The exposure of several landforms and proglacial deposits, such as flutes, kame terraces, morainic ridges, clast pavements, striated rocks and eskers all result from retraction. Abraded and subglacially transported sediments predominate at the deglaciation environment with meltwater. A large proportion of fine- grained sediments, striated rock surfaces, clast pavements, stoss and lee blocks, indicate that the two glaciers are wet based, having a temperate basal thermal regime.
Publication Type journal article
Record ID 65006400