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Lookup NU author(s): Professor Andrew RussellORCiD
This paper characterises the sedimentary impact of a glacial outburst flood or 'jökulhlaup' on an ice-contact delta topset at Russell Glacier, Kangerlussuaq, west Greenland. Rapid drainage of an ice-dammed lake in July 1987 generated a jökulhlaup with a peak discharge of ∼ 1300 m3 s- 1, which drained across a 500-m-wide, 200-m-long, delta top into a proglacial lake. The delta topset comprises boulder clusters, ice block obstacle marks with relief of up to 4 m, and is graded to lake levels up to 6 m higher than those during typical non-jökulhlaup conditions. The delta top was dissected by the 1987 jökulhlaup causing a fan-shaped extension of the delta front by 30 m. Surface grain size on the delta decreases rapidly away from the main flood flow direction, reflecting rapid downstream reduction in sediment transport capacity. The 1987 jökulhlaup was predominantly fluidal and turbulent and had peak stream powers of 2846 W m- 2 proximally and < 400 W m- 2 distally. Delta topset sedimentation can be characterised by four lithofacies associations in order of decreasing flow energy: (A) coarse-grained deposits related to a flow expansion; (B) finer-grained peripheral deposits located at the margins of the main flow; (C) lobate bars and delta fronts deposited within distal locations and (D) fine-grained deposits at distance from the delta front associated with slackwater conditions. Jökulhlaup-dominated delta topsets are controlled by the geometry of the channel expansion into the proglacial lake, jökulhlaup hydrograph form, the sediment availability and character, proglacial lake basin depth and surface area, lake outflow spillway erodibility and cross-sectional area, and history of previous jökulhlaups. © 2006 Elsevier B.V. All rights reserved.
Author(s): Russell AJ
Publication type: Article
Publication status: Published
Journal: Sedimentary Geology
Year: 2007
Volume: 193
Issue: 1-4
Pages: 131-148
Print publication date: 01/01/2007
Date deposited: 16/06/2014
ISSN (print): 0037-0738
ISSN (electronic):
URL: http://dx.doi.org/10.1016/j.sedgeo.2006.01.007
DOI: 10.1016/j.sedgeo.2006.01.007
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