Facial reconstruction

Search LJMU Research Online

Browse Repository | Browse E-Theses

New constraints on Greenland ice sheet dynamics during the last glacial cycle: Evidence from the Uummannaq ice stream system

Roberts, DH and Rea, BR and Lane, TP 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. ISSN 2169-9011

[img] Text
Roberts_et_al-2013-Journal_of_Geophysical_Research-_Earth_Surface (1).pdf - Published Version

Download (11MB)

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
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 and Psychology
Publisher: American Geophysical Union
Date Deposited: 18 Dec 2015 08:37
Last Modified: 18 Dec 2015 08:37
DOI or Identification number: 10.1002/jgrf.20032
URI: http://researchonline.ljmu.ac.uk/id/eprint/2502

Actions (login required)

View Item View Item