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Roberts, DH, Rea, BR, Lane, TP, 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. ISSN 2169-9011
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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 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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| Additional Information: | An edited version of this paper was published by AGU. Copyright 2013 American Geophysical Union. To view the published open abstract, go to http://dx.doi.org/10.1002/jgrf.20032 |
| Subjects: | G Geography. Anthropology. Recreation > GB Physical geography |
| Divisions: | Natural Sciences & Psychology (closed 31 Aug 19) |
| Publisher: | American Geophysical Union |
| Date Deposited: | 18 Dec 2015 08:37 |
| Last Modified: | 04 Sep 2021 13:43 |
| DOI or ID number: | 10.1002/jgrf.20032 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/2502 |
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