Chemical depletion of sediment under the Greenland Ice Sheet
Abstract The chemical composition of sediment sampled from a network of ice boreholes contacting the bed of the ablation zone of the Greenland Ice Sheet is compared to the composition of intact bedrock clasts. This sediment is enriched in silica and depleted in reactive cations compared to the under...
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crwiley:10.1002/esp.3960 2024-06-02T08:07:27+00:00 Chemical depletion of sediment under the Greenland Ice Sheet Graly, Joseph A. Humphrey, Neil F. Harper, Joel T. 2016 http://dx.doi.org/10.1002/esp.3960 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fesp.3960 https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.3960 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Earth Surface Processes and Landforms volume 41, issue 13, page 1922-1936 ISSN 0197-9337 1096-9837 journal-article 2016 crwiley https://doi.org/10.1002/esp.3960 2024-05-03T10:39:26Z Abstract The chemical composition of sediment sampled from a network of ice boreholes contacting the bed of the ablation zone of the Greenland Ice Sheet is compared to the composition of intact bedrock clasts. This sediment is enriched in silica and depleted in reactive cations compared to the underlying bedrock. In order to test whether these differences result from grain size biases either in sample collection or due to natural sorting, sediment samples were analyzed by grain size aliquots. Enrichment of silicon and depletion of cations is consistent across grain size classes and the compositions of bedrock and subglacial sediment are statistically separate. The difference in composition between subglacial sediment and rock aligns closely with the composition of dissolved solutes in waters sampled from the same field sites and is dissimilar to the composition of the sites' suspended sediment. This implies that chemical weathering rather than disproportionate physical removal of friable minerals is responsible for the compositional differences between rock and sediment. Mass balance analysis implies 3–10% of the sediment's mass is lost to solute dissolution, with approximately double that amount precipitated as clay minerals (a large portion of which may have been physically expelled). This result implies that temperate ice sheet subglacial environments may be more chemically active than previously realized. Copyright © 2016 John Wiley & Sons, Ltd. Article in Journal/Newspaper Greenland Ice Sheet Wiley Online Library Greenland Earth Surface Processes and Landforms 41 13 1922 1936 |
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English |
description |
Abstract The chemical composition of sediment sampled from a network of ice boreholes contacting the bed of the ablation zone of the Greenland Ice Sheet is compared to the composition of intact bedrock clasts. This sediment is enriched in silica and depleted in reactive cations compared to the underlying bedrock. In order to test whether these differences result from grain size biases either in sample collection or due to natural sorting, sediment samples were analyzed by grain size aliquots. Enrichment of silicon and depletion of cations is consistent across grain size classes and the compositions of bedrock and subglacial sediment are statistically separate. The difference in composition between subglacial sediment and rock aligns closely with the composition of dissolved solutes in waters sampled from the same field sites and is dissimilar to the composition of the sites' suspended sediment. This implies that chemical weathering rather than disproportionate physical removal of friable minerals is responsible for the compositional differences between rock and sediment. Mass balance analysis implies 3–10% of the sediment's mass is lost to solute dissolution, with approximately double that amount precipitated as clay minerals (a large portion of which may have been physically expelled). This result implies that temperate ice sheet subglacial environments may be more chemically active than previously realized. Copyright © 2016 John Wiley & Sons, Ltd. |
format |
Article in Journal/Newspaper |
author |
Graly, Joseph A. Humphrey, Neil F. Harper, Joel T. |
spellingShingle |
Graly, Joseph A. Humphrey, Neil F. Harper, Joel T. Chemical depletion of sediment under the Greenland Ice Sheet |
author_facet |
Graly, Joseph A. Humphrey, Neil F. Harper, Joel T. |
author_sort |
Graly, Joseph A. |
title |
Chemical depletion of sediment under the Greenland Ice Sheet |
title_short |
Chemical depletion of sediment under the Greenland Ice Sheet |
title_full |
Chemical depletion of sediment under the Greenland Ice Sheet |
title_fullStr |
Chemical depletion of sediment under the Greenland Ice Sheet |
title_full_unstemmed |
Chemical depletion of sediment under the Greenland Ice Sheet |
title_sort |
chemical depletion of sediment under the greenland ice sheet |
publisher |
Wiley |
publishDate |
2016 |
url |
http://dx.doi.org/10.1002/esp.3960 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fesp.3960 https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.3960 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_source |
Earth Surface Processes and Landforms volume 41, issue 13, page 1922-1936 ISSN 0197-9337 1096-9837 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/esp.3960 |
container_title |
Earth Surface Processes and Landforms |
container_volume |
41 |
container_issue |
13 |
container_start_page |
1922 |
op_container_end_page |
1936 |
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1800752525855424512 |