Controls on the sedimentary architecture of a single event englacial esker: Skeiðarárjökull, Iceland

Burke, Matthew John, Woodward, John, Russell, Andrew J., Fleisher, P. Jay and Bailey, Palmer (2008) Controls on the sedimentary architecture of a single event englacial esker: Skeiðarárjökull, Iceland. Quaternary Science Reviews, 27 (19-20). pp. 1829-1847. ISSN 0277-3791

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Abstract

Eskers have been used to infer the dynamics and palaeo-hydrology of large ice sheets yet there are few suitable contemporary analogues for esker sedimentation during Quaternary glaciations. Consequently, models of esker sedimentation have been derived from morpho-sedimentary analyses of Quaternary eskers, but these lack rigorous constraints on their depositional timescales. We identify the controls on the large-scale sedimentary architecture of a large (>700 m long, <30 m high) proto-esker deposited during a single, high-magnitude jökulhlaup at Skeiðarárjökull, Iceland. Over 3.8 km of ground-penetrating radar (GPR) lines were collected (in 2006 and 2007) as grids on all workable areas of the proto-esker and associated supraglacial ice-walled canyon-fill sediment. Six main radar facies were identified: (1) discontinuous, undular reflections, interpreted as trough-cross strata, associated with the development of antidune or dune sequences; (2) sub-horizontal reflections (dip <10°), associated with deposition of upper-stage gravel plane beds; (3) up-flow dipping moderate to high-angle (>10°) inclined reflections, interpreted as backset accretion associated with large-scale bedform development; (4) down-flow dipping high-angle (>15°) inclined reflections, interpreted as foreset accretion associated with macroform progradation; (5) quasi-hyperbolic reflections, interpreted as zones of boulder clustering; and (6) zones of enhanced noise and EM signal attenuation, bounded on the upper surface by a continuous reflection sub-parallel to the ground surface, interpreted as buried ice associated with the conduit/channel base. These data suggest that deposition took place within a non-uniform englacial conduit, which has resulted in major up-flow to down-flow variations in sedimentary architecture. The complexities observed are a direct consequence of variations in sediment supply and the within-event evolution of conduit geometry. This study provides the first detailed insight into the large-scale sedimentary architecture of a single event jökulhlaup proto-esker.

Item Type:	Article
Uncontrolled Keywords:	paleohydrology, quaternary, ice sheets, sedimentation analysis
Subjects:	F600 Geology
Department:	Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User:	EPrint Services
Date Deposited:	03 Sep 2009 08:48
Last Modified:	13 Oct 2019 00:24
URI:	http://nrl.northumbria.ac.uk/id/eprint/1611

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