Roberts, D.H. and Rea, B. and Lane, T. and Schnabel, C. and Rodés, 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.
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 above sea level (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 B.P., 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 B.P., 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 B.P. Local fjord constriction temporarily stabilized the unzipped UISS margins at the start of the Holocene before ice retreat inland of the current margin at ~8.7 ka.
Item Type: | Article |
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Full text: | (VoR) Version of Record Download PDF (11701Kb) |
Full text: | Publisher-imposed embargo (AM) Accepted Manuscript File format - PDF (Copyright agreement prohibits open access to the full-text) (3373Kb) |
Status: | Peer-reviewed |
Publisher Web site: | http://dx.doi.org/10.1002/jgrf.20032 |
Publisher statement: | Roberts, D. H., B. R. Rea, T. P. Lane, C. Schnabel, and A. Rodés (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, 519-541, 10.1002/jgrf.20032 (DOI). To view the published open abstract, go to http://dx.doi.org and enter the DOI. |
Date accepted: | 11 July 2013 |
Date deposited: | 07 March 2016 |
Date of first online publication: | June 2013 |
Date first made open access: | No date available |
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