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Lookup NU author(s): Dr Matthew Burke, Professor Andrew RussellORCiD
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The rising stage of the November 1996 jökulhlaup travelled through a dense fracture network that perforated the margin of Skeiðarárjökull, Iceland. Later during the jökulhlaup, discharge focussed upon a small number of conduit outlets. Recent ice-marginal retreat has exposed a large englacial esker associated with one of these outlets. In April 2006, over 2.5 km of GPR line were collected on the glacier surface up-glacier of the partially melted out esker ridge, to investigate structural controls on esker genesis. In lines closest to the partly exposed esker, internal structure can be recognized in ‘zones’ of englacial reflections up to ~30 m wide and ~10-20 m in height, interpreted as a continuation of the forefield partially exposed esker. A strong, planar surface defines the base of the esker across many lines. Similar planar surfaces are found deeper in the profile suggesting that: 1) the planar surface beneath the proto-esker is englacial; 2) Floodwaters were discharged along a structurally controlled englacial surface; 3) During discharge, conduits developed at this surface due to localised excavation of surrounding glacier ice; 4) Sedimentation took place within the new accommodation space to form an englacial conduit-fill esker. This study provides the first observation of englacial structural control upon conduit development and proto-esker formation during a high-magnitude jökulhlaup.
Author(s): Burke MJ, Woodward J, Russell AJ, Fleisher PJ
Publication type: Article
Publication status: Published
Journal: Annals of Glaciology
Year: 2009
Volume: 50
Issue: 51
Pages: 85-92
ISSN (print): 0260-3055
ISSN (electronic): 1727-5644
Publisher: International Glaciological Society
URL: http://dx.doi.org/10.3189/172756409789097568
DOI: 10.3189/172756409789097568
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