The geomorphological record of an ice stream to ice shelf transition in Northeast Greenland

T.P. Lane* (Corresponding Author), C.M. Darvill, , Brice Rea, M.J Bentley, James A. Smith, S.S.R Jamieson, C.Ó. Cofaigh, D.H. Roberts

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
2 Downloads (Pure)

Abstract

Understanding ice stream dynamics over decadal to millennial timescales is
crucial for improving numerical model projections of ice sheet behaviour and
future ice loss. In marine-terminating settings, ice shelves play a critical role in
controlling ice-stream grounding line stability and ice flux to the ocean, but few
studies have investigated the terrestrial lateral geomorphological imprint of ice
shelves during deglaciation. Here, we document the terrestrial deglacial
landsystem of Nioghalvfjerdsfjorden Glacier (79N) in Northeast Greenland,
following the Last Glacial Maximum, and the margin’s lateral transition to a
floating ice shelf. High-elevation areas are influenced by local ice caps and display autochthonous to allochthonous blockfields that mark the interaction of local ice caps with the ice stream below. A thermal transition from cold- to warm-based ice is denoted by the emplacement of erratics onto allochthonous blockfields. Below ~600 m a.s.l. glacially abraded bedrock surfaces and assemblages of lateral moraines, ‘hummocky’ moraine, fluted terrain, and ice-contact deltas record the former presence of warm-based ice and thinning of the grounded ice stream margin through time. In the outer fjord a range of landforms such as ice shelf moraines, dead-ice topography, and weakly developed ice marginal glaciofluvial outwash was produced by an ice shelf during deglaciation. Along the mid- and inner-fjord areas this ice shelf signal is absent, suggesting ice shelf disintegration prior to grounding line retreat under tidewater conditions. However, below the marine limit, the geomorphological record along the fjord indicates the expansion of the 79N ice shelf during the Neoglacial, which culminated in the Little Ice Age. This was followed by 20th Century recession, with the development of a suite of compressional ice shelf moraines, ice-marginal fluvioglacial corridors, kame terraces, dead-ice terrain, and crevasse infill ridges. These mark rapid ice shelf thinning and typify the present-day ice shelf landsystem in a warming climate.
Original languageEnglish
Pages (from-to)1321-1341
Number of pages21
JournalEarth Surface Processes and Landforms
Volume48
Issue number7
Early online date10 Feb 2023
DOIs
Publication statusPublished - 15 Jun 2023

Bibliographical note

ACKNOWLEDGEMENTS
This work was funded through NERC Standard Grant NE/N011228/1. We thank
the Alfred Wegner Institute, and particularly Angelika Humbert and Hicham Rafiq, for their logistic support through the iGRIFF project. Further support was provided from Station Nord (Jorgen Skafte), Nordland Air, Air Greenland, and the Joint Arctic Command. Naalakkersuisut, Government of Greenland, provided Scientific Survey (VU-00121) and Export (046/2017) licences for this work. We thank Chris Orton for help with production of figures. Finally, we would like to thank our Field Ranger Isak (after which Isakdalen is informally named) and dog Ooni for keeping us safe in the field. We thank Rob Storrar and an anonymous reviewer for their comments which helped improve the manuscript.

Data Availability Statement

Shapefile data will be stored on the UK Polar Data Centre; https://www.bas.ac.uk/data/uk-pdc/

Keywords

  • geomorphology
  • Greenland
  • ice shelf
  • ice stream
  • palaeoglaciology

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