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Late Quaternary ice flow in a West Greenland fjord and cross-shelf trough system : submarine landforms from Rink Isbrae to Uummannaq shelf and slope.

Dowdeswell, J.A. and Hogan, K.A. and Ó Cofaigh, C. and Fugelli, E.M.G. and Evans, J. and Noormets, R. (2014) 'Late Quaternary ice flow in a West Greenland fjord and cross-shelf trough system : submarine landforms from Rink Isbrae to Uummannaq shelf and slope.', Quaternary science reviews., 92 . pp. 292-309.

Abstract

Sea-floor landforms and acoustic-stratigraphic records allow interpretation of the past form and flow of a westward-draining ice stream of the Greenland Ice Sheet, Rink Isbrae. The Late Pliocene–Pleistocene glacial package is several hundred metres thick and down-laps onto an upper Miocene horizon. Several acoustic facies are mapped from sub-bottom profiler records of the 400 km-long Uummannaq fjord-shelf-slope system. An acoustically stratified facies covers much of the fjord and trough floor, interpreted as glacimarine sediment from rain-out of fine-grained debris in turbid meltwater. Beneath this facies is a semi-transparent deformation-till unit, which includes buried streamlined landforms. Landform distribution in the Uummannaq system is used to reconstruct past ice extent and flow directions. The presence of streamlined landforms (mega-scale glacial lineations, drumlins, crag-and-tails) shows that an ice stream advanced through the fjord system to fill Uummannaq Trough, reaching the shelf edge at the Last Glacial Maximum. Beyond the trough there is a major fan built mainly of glacigenic debris flows. Turbidity-current channels were not observed on Uummannaq Fan, contrasting with well-developed channels on Disko Fan, 300 km to the south. Ice retreat had begun by 14.8 cal. ka ago. Grounding-zone wedges (GZW) in Uummannaq Trough imply that retreat was episodic, punctuated by several still-stands. Ice retreat between GZWs may have been relatively rapid. There is little sedimentary evidence for still-stands in the inner fjords, except for a major moraine ridge marking a Little Ice Age maximum position. On the shallow banks either side of Uummannaq Trough, iceberg ploughing has reworked any morphological evidence of earlier ice-sheet activity.

Item Type:Article
Keywords:Arctic, Ice flow, Ice stream, Late Quaternary, Submarine landforms, Trough-mouth fan, West Greenland.
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Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1016/j.quascirev.2013.09.007
Publisher statement:© 2013 The Authors. Published by Elsevier Ltd. Open access under CC BY license.
Date accepted:12 September 2013
Date deposited:09 December 2014
Date of first online publication:01 November 2013
Date first made open access:No date available

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