Roberts, D. H., Rea, B. R., Lane, T. P., Schnabel, C. and Rodes, A. (2013) New constraints on Greenland ice sheet dynamics during the last glacial cycle: evidence from the Uummannaq ice stream system. Journal of Geophysical Research: Earth Surface, 118(2), pp. 519-541. (doi: 10.1002/jgrf.20032)
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Abstract
This paper presents the first assessment of the Uummannaq ice stream system (UISS) in West Greenland. The UISS drained ~6% of the Greenland ice sheet (GrIS) at the Last Glacial Maximum (LGM). The onset of the UISS is a function of a convergent network of fjords which feed a geologically-controlled trough system running offshore to the shelf break. Mapping, cosmogenic radiogenic nuclide (CRN) dating and model output reveal that glacially scoured surfaces up to 1266 m asl in fjord-head areas were produced by warm-based ice moving offshore during the LGM, with the elevation of warm-based ice dropping westwards to ~700 m asl as the ice stream trunk zone developed. Marginal plateaux with allochthonous blockfields suggest that warm-based ice produced till and erratics up to ~1200 m asl, but CRN ages and weathering pits suggest this was pre-LGM, with only cold-based ice operating during the LGM. Deglaciation began on the outer shelf at ~14.8 cal. kyrs BP, with Ubekendt Ejland becoming ice free at ~12.4 ka. The UISS then collapsed with over 100 km of retreat by ~11.4 ka – 10.8 cal. kyrs BP; a rapid and complex response to bathymetric deepening, trough widening and sea-level rise coinciding with rapidly increasing air temperatures and solar radiation, but which occurred prior to ocean warming at ~8.4 cal. kyrs BP. Local fjord constriction temporarily stabilised the unzipped UISS margins at the start of the Holocene before ice retreat inland of the current margin at ~8.7 ka.
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Schnabel, Dr Christoph and Rodes, Dr Angel |
Authors: | Roberts, D. H., Rea, B. R., Lane, T. P., Schnabel, C., and Rodes, A. |
College/School: | College of Science and Engineering > Scottish Universities Environmental Research Centre |
Journal Name: | Journal of Geophysical Research: Earth Surface |
Publisher: | Wiley-Blackwell |
ISSN: | 2169-9003 |
ISSN (Online): | 2169-9011 |
Published Online: | 02 May 2013 |
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