The Effects of Glacier-Outburst Flood Flow Dynamics on Ice-Contact Deposits: November 1996 Jökulhlaup, Skeiðarársandur, Iceland

  1. I. Peter Martini3,
  2. Victor R. Baker4 and
  3. Guillermina Garzón5
  1. A. J. Russell1 and
  2. Ó. Knudsen2

Published Online: 17 MAR 2009

DOI: 10.1002/9781444304299.ch5

Flood and Megaflood Processes and Deposits: Recent and Ancient Examples

Flood and Megaflood Processes and Deposits: Recent and Ancient Examples

How to Cite

Russell, A. J. and Knudsen, Ó. (2002) The Effects of Glacier-Outburst Flood Flow Dynamics on Ice-Contact Deposits: November 1996 Jökulhlaup, Skeiðarársandur, Iceland, in Flood and Megaflood Processes and Deposits: Recent and Ancient Examples (eds I. P. Martini, V. R. Baker and G. Garzón), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304299.ch5

Editor Information

  1. 3

    Department of Land Resource Science, University of Guelph, Guelph, Ontario, Canada

  2. 4

    Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721–0011, USA

  3. 5

    Dpto de Geodinámica, Fac. de Geología, Universidad of Complutense, 28040 Madrid, Spain

Author Information

  1. 1

    School of Earth Sciences and Geography, Keele University, Keele, Staffordshire ST5 5BG, UK

  2. 2

    Klettur Consulting Engineers, Bíldshöfða 12, IS 112, Reykjavík, Iceland

Publication History

  1. Published Online: 17 MAR 2009
  2. Published Print: 10 FEB 2002

ISBN Information

Print ISBN: 9780632064045

Online ISBN: 9781444304299

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Keywords:

  • effects of glacier-outburst flood flow dynamics on ice-contact deposits - November 1996 jökulhlaup, Skeiðarársandur, Iceland;
  • November 1996 jökulhlaup;
  • falling stage outlet deposits;
  • multiple stage deposits;
  • Sæluhúsakvísl and western Skeiðará A and B;
  • ice blocks and flow stage

Summary

This study examines the extent to which observed large-scale stage variations are reflected in the proglacial landform and sedimentary record of the November 1996 jökulhlaup, Skeiðarárjökull, Iceland. Discrimination of rising from falling flood stage landforms and deposits usually is based upon the interpretation of the geomorphological and sedimentary record. Sedimentary successions in proglacial environments have been interpreted on the basis of vertical sedimentary characteristics, which are then linked to the flood hydrograph. Spatial segregation of rising and falling stage proglacial outwash during the November 1996 jökulhlaup provided a superb opportunity to examine the role of flow stage in the creation and preservation of distinctive proglacial jökulhlaup landforms and deposits. Rising stage deposits contain finer, more poorly sorted sediment than found in falling stage successions and on erosional surfaces. Rising stage deposits show one or more upward-coarsening successions, characteristic of progressive supply of coarser grained sediment with stage increase, compatible with previous models of rising stage sedimentation. Some rising stage successions, however, show few signs of large-scale grading, and instead contain repeated cycles of sedimentation, recording individual sedimentation pulses. Distinctive upward-coarsening successions on a waning stage outwash fan were generated by sediment winnowing resulting in progressive bed coarsening from matrix-supported gravels to clast-rich armour. The presence of an upward-coarsening succession alone is clearly not diagnostic of rising stage deposition. Conduits occupied by flows on both rising and falling flow stages were characterized by initial rising stage fan deposition followed by falling stage dissection and exhumation of ice blocks and intraclasts deposited on the rising flow stage. Where waning stage flows were routed through a single conduit, high sediment efflux and aggradation rates were maintained late into the waning stage. This study illustrates the geomorphological and sedimentary significance of major within-jökulhlaup sediment reworking and ice-margin erosion over distances of 102–103 m.