Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skeiđarárjökull, Iceland
Abstract This paper presents sedimentary evidence for rapid englacial debris entrainment during jökulhlaups. Previous studies of jökulhlaup sedimentology have focused predominantly on proglacial impact, rather than depositional processes within glaciers. However, observations of supraglacial floodwa...
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crwiley:10.1002/esp.236 2024-09-15T18:07:50+00:00 Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skeiđarárjökull, Iceland Roberts, Matthew J. Russell, Andrew J. Tweed, Fiona S. Knudsen, Óskar 2001 http://dx.doi.org/10.1002/esp.236 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fesp.236 https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.236 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Earth Surface Processes and Landforms volume 26, issue 9, page 935-952 ISSN 0197-9337 1096-9837 journal-article 2001 crwiley https://doi.org/10.1002/esp.236 2024-07-25T04:22:47Z Abstract This paper presents sedimentary evidence for rapid englacial debris entrainment during jökulhlaups. Previous studies of jökulhlaup sedimentology have focused predominantly on proglacial impact, rather than depositional processes within glaciers. However, observations of supraglacial floodwater outbursts suggest that englacial sediment emplacement is possible during jökulhlaups. The November 1996 jökulhlaup from Skeiđarárjökull, Iceland presented one of the first opportunities to examine englacial flood deposits in relation to former supraglacial outlets. Using observations from Skeiđarárjökull, this paper identifies and explains controls on the deposition of englacial flood sediments and presents a qualitative model for englacial jökulhlaup deposition. Englacial jökulhlaup deposits were contained within complex networks of upglacier‐dipping fractures. Simultaneous englacial deposition of fines and boulder‐sized sediment demonstrates that englacial fracture discharge had a high transport capacity. Fracture geometry was an important control on the architecture of englacial jökulhlaup deposits. The occurrence of pervasively frozen flood deposits within Skeiđarárjökull is attributed to freeze‐on by glaciohydraulic supercooling. Floodwater, flowing subglacially or through upglacier‐dipping fractures, would have supercooled as it was raised to the surface faster than its pressure‐melting point could increase as glaciostatic pressure decreased. Evidence for floodwater contact with the glacier bed is supported by the ubiquitous occurrence of sheared diamict rip‐ups and intra‐clasts of basal ice within jökulhlaup fractures, deposited englacially some 200–350 m above the bed of Skeiđarárjökull. Evidence for fluidal supercooled sediment accretion is apparent within stratified sands, deposited englacially at exceptionally high angles of rest in the absence of post‐depositional disturbance. Such primary sediment structures cannot be explained unless sediment is progressively accreted to opposing fracture walls. Ice ... Article in Journal/Newspaper glacier Iceland Wiley Online Library Earth Surface Processes and Landforms 26 9 935 952 |
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Wiley Online Library |
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English |
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Abstract This paper presents sedimentary evidence for rapid englacial debris entrainment during jökulhlaups. Previous studies of jökulhlaup sedimentology have focused predominantly on proglacial impact, rather than depositional processes within glaciers. However, observations of supraglacial floodwater outbursts suggest that englacial sediment emplacement is possible during jökulhlaups. The November 1996 jökulhlaup from Skeiđarárjökull, Iceland presented one of the first opportunities to examine englacial flood deposits in relation to former supraglacial outlets. Using observations from Skeiđarárjökull, this paper identifies and explains controls on the deposition of englacial flood sediments and presents a qualitative model for englacial jökulhlaup deposition. Englacial jökulhlaup deposits were contained within complex networks of upglacier‐dipping fractures. Simultaneous englacial deposition of fines and boulder‐sized sediment demonstrates that englacial fracture discharge had a high transport capacity. Fracture geometry was an important control on the architecture of englacial jökulhlaup deposits. The occurrence of pervasively frozen flood deposits within Skeiđarárjökull is attributed to freeze‐on by glaciohydraulic supercooling. Floodwater, flowing subglacially or through upglacier‐dipping fractures, would have supercooled as it was raised to the surface faster than its pressure‐melting point could increase as glaciostatic pressure decreased. Evidence for floodwater contact with the glacier bed is supported by the ubiquitous occurrence of sheared diamict rip‐ups and intra‐clasts of basal ice within jökulhlaup fractures, deposited englacially some 200–350 m above the bed of Skeiđarárjökull. Evidence for fluidal supercooled sediment accretion is apparent within stratified sands, deposited englacially at exceptionally high angles of rest in the absence of post‐depositional disturbance. Such primary sediment structures cannot be explained unless sediment is progressively accreted to opposing fracture walls. Ice ... |
format |
Article in Journal/Newspaper |
author |
Roberts, Matthew J. Russell, Andrew J. Tweed, Fiona S. Knudsen, Óskar |
spellingShingle |
Roberts, Matthew J. Russell, Andrew J. Tweed, Fiona S. Knudsen, Óskar Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skeiđarárjökull, Iceland |
author_facet |
Roberts, Matthew J. Russell, Andrew J. Tweed, Fiona S. Knudsen, Óskar |
author_sort |
Roberts, Matthew J. |
title |
Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skeiđarárjökull, Iceland |
title_short |
Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skeiđarárjökull, Iceland |
title_full |
Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skeiđarárjökull, Iceland |
title_fullStr |
Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skeiđarárjökull, Iceland |
title_full_unstemmed |
Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skeiđarárjökull, Iceland |
title_sort |
controls on englacial sediment deposition during the november 1996 jökulhlaup, skeiđarárjökull, iceland |
publisher |
Wiley |
publishDate |
2001 |
url |
http://dx.doi.org/10.1002/esp.236 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fesp.236 https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.236 |
genre |
glacier Iceland |
genre_facet |
glacier Iceland |
op_source |
Earth Surface Processes and Landforms volume 26, issue 9, page 935-952 ISSN 0197-9337 1096-9837 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/esp.236 |
container_title |
Earth Surface Processes and Landforms |
container_volume |
26 |
container_issue |
9 |
container_start_page |
935 |
op_container_end_page |
952 |
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1810445193691791360 |