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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.; Hogan, K.A.; Ó Cofaigh, C.; Fugelli, E.M.G.; Evans, J.; Noormets, R.

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


Authors

J.A. Dowdeswell

K.A. Hogan

E.M.G. Fugelli

J. Evans

R. Noormets



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.

Citation

Dowdeswell, J., Hogan, K., Ó Cofaigh, C., Fugelli, E., Evans, J., & 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, 292-309. https://doi.org/10.1016/j.quascirev.2013.09.007

Journal Article Type Article
Acceptance Date Sep 12, 2013
Online Publication Date Nov 1, 2013
Publication Date May 15, 2014
Deposit Date May 15, 2014
Publicly Available Date Mar 29, 2024
Journal Quaternary Science Reviews
Print ISSN 0277-3791
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 92
Pages 292-309
DOI https://doi.org/10.1016/j.quascirev.2013.09.007
Keywords Arctic, Ice flow, Ice stream, Late Quaternary, Submarine landforms, Trough-mouth fan, West Greenland.

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