Abstract

PONCE, Juan F.; RABASSA, Jorge; SERRAT, David  and  MARTINEZ, Oscar A.. The drumlin, flute and megaflute field of lago Viedma (Late Pleistocene, Santa Cruz province). Rev. Asoc. Geol. Argent. [online]. 2013, vol.70, n.1, pp.115-127. ISSN 0004-4822.

A new drumlin, flute and megaflute field has been identified in the eastern shores of lago Viedma (49º 48' S, 77º 55' W). In this paper, their geomorphological components are identified and described. This subglacial landform field is part of the Last Glaciation ground moraines. A minimum of 19 drumlins and 199 flutes and megaflutes have been identified. A detailed morphometric study has been completed on a selected sample of 101 landforms. The study shows that megaflutes are much more frequent than flutes and drumlins, which is probably related to glacier dynamics and bed load conditions. Their azimuth orientations have been surveyed for each sector and longitudinal and transversal profiles have been measured in the field on selected landforms. In addition, it has been determined that the main axes orientation is almost sub-parallel in each of the identified sectors, but it is substantially different between the northern sector (ranging from N 85º E to N 37º E) and the southern sector (between N 145º SE and N 133º SE). This characteristic demonstrates that the landforms have been generated at the base of the Finiglacial lobe of the Viedma Paleoglacier, when this ice body abandoned the valley where it was confined and in which it had eroded the glacial valley that it is presently occupied by lago Viedma, and afterwards expanding and extending eastwards as a piedmont glacier.

Keywords : Geomorphology; Glacial; Patagonia.

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