Silicon isotope variations accompanying basalt weathering in Iceland
This study presents the Si isotope compositions of the dissolved phase of twenty rivers from across Iceland. The high-resolution Nu Plasma 1700 MC-ICP-MS was used to provide interference-free 30Si/28Si ratios with an average limiting precision of ± 0.04‰ δ30Si. The Si isotope composition ranges from...
Published in: | Earth and Planetary Science Letters |
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2016
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Online Access: | https://doi.org/10.1016/j.epsl.2007.07.004 https://ora.ox.ac.uk/objects/uuid:c7156dbc-211a-46e7-9dcd-d7b7b809b07b |
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ftuloxford:oai:ora.ox.ac.uk:uuid:c7156dbc-211a-46e7-9dcd-d7b7b809b07b 2023-05-15T16:47:44+02:00 Silicon isotope variations accompanying basalt weathering in Iceland Georg, R Reynolds, B West, A Burton, K Halliday, A 2016-07-29 https://doi.org/10.1016/j.epsl.2007.07.004 https://ora.ox.ac.uk/objects/uuid:c7156dbc-211a-46e7-9dcd-d7b7b809b07b eng eng doi:10.1016/j.epsl.2007.07.004 https://ora.ox.ac.uk/objects/uuid:c7156dbc-211a-46e7-9dcd-d7b7b809b07b https://doi.org/10.1016/j.epsl.2007.07.004 info:eu-repo/semantics/embargoedAccess Journal article 2016 ftuloxford https://doi.org/10.1016/j.epsl.2007.07.004 2022-06-28T20:23:34Z This study presents the Si isotope compositions of the dissolved phase of twenty rivers from across Iceland. The high-resolution Nu Plasma 1700 MC-ICP-MS was used to provide interference-free 30Si/28Si ratios with an average limiting precision of ± 0.04‰ δ30Si. The Si isotope composition ranges from - 0.08‰ to 1.46‰ δ30Si, averaging 0.63 ± 0.38‰ (± 1σSD). This is only slightly lighter than the recently reported mean of 0.84 ± 0.19‰ for high precision measurements of Swiss rivers but is significantly lighter than compositions reported for some other rivers. The Si isotope composition varies slightly with the amount of glacial cover, which provides evidence that the continental Si input to the oceans may be climatically controlled and thus likely to vary over glacial-interglacial cycles. After correction for the dissolution of trace amounts of calcite in one region, a correlation is found between δ30Si and Ca/Si. This is consistent with the measured basaltic composition and indicates isotopic fractionation during Si removal from the dissolved phase. By calculating the fraction of Si that is removed from the dissolved phase into secondary phases it is possible to use the riverine Si flux (Si denudation rate) to calculate the initial dissolution rate of Si within these catchments. From this study we estimate that the total amount of Si being dissolved by primary weathering of Iceland is 3 million tons per yr. However only ∼ 50% of this Si is released into the rivers and contributes to denudation. Using the Si isotope composition and the Si fraction removed, it is possible to model the Si isotope fractionation as either a Rayleigh-type fractionation or a steady-state system. Both yield similar fractionation factors of about - 1.5‰ δ30Si, implying only one underlying fractionation process that is controlled by external parameters, such as runoff. Furthermore, rivers that follow a steady-state fractionation model are associated with higher Si dissolution rates and lower δ30Si values, indicating an inverse relationship ... Article in Journal/Newspaper Iceland ORA - Oxford University Research Archive Earth and Planetary Science Letters 261 3-4 476 490 |
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Open Polar |
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ORA - Oxford University Research Archive |
op_collection_id |
ftuloxford |
language |
English |
description |
This study presents the Si isotope compositions of the dissolved phase of twenty rivers from across Iceland. The high-resolution Nu Plasma 1700 MC-ICP-MS was used to provide interference-free 30Si/28Si ratios with an average limiting precision of ± 0.04‰ δ30Si. The Si isotope composition ranges from - 0.08‰ to 1.46‰ δ30Si, averaging 0.63 ± 0.38‰ (± 1σSD). This is only slightly lighter than the recently reported mean of 0.84 ± 0.19‰ for high precision measurements of Swiss rivers but is significantly lighter than compositions reported for some other rivers. The Si isotope composition varies slightly with the amount of glacial cover, which provides evidence that the continental Si input to the oceans may be climatically controlled and thus likely to vary over glacial-interglacial cycles. After correction for the dissolution of trace amounts of calcite in one region, a correlation is found between δ30Si and Ca/Si. This is consistent with the measured basaltic composition and indicates isotopic fractionation during Si removal from the dissolved phase. By calculating the fraction of Si that is removed from the dissolved phase into secondary phases it is possible to use the riverine Si flux (Si denudation rate) to calculate the initial dissolution rate of Si within these catchments. From this study we estimate that the total amount of Si being dissolved by primary weathering of Iceland is 3 million tons per yr. However only ∼ 50% of this Si is released into the rivers and contributes to denudation. Using the Si isotope composition and the Si fraction removed, it is possible to model the Si isotope fractionation as either a Rayleigh-type fractionation or a steady-state system. Both yield similar fractionation factors of about - 1.5‰ δ30Si, implying only one underlying fractionation process that is controlled by external parameters, such as runoff. Furthermore, rivers that follow a steady-state fractionation model are associated with higher Si dissolution rates and lower δ30Si values, indicating an inverse relationship ... |
format |
Article in Journal/Newspaper |
author |
Georg, R Reynolds, B West, A Burton, K Halliday, A |
spellingShingle |
Georg, R Reynolds, B West, A Burton, K Halliday, A Silicon isotope variations accompanying basalt weathering in Iceland |
author_facet |
Georg, R Reynolds, B West, A Burton, K Halliday, A |
author_sort |
Georg, R |
title |
Silicon isotope variations accompanying basalt weathering in Iceland |
title_short |
Silicon isotope variations accompanying basalt weathering in Iceland |
title_full |
Silicon isotope variations accompanying basalt weathering in Iceland |
title_fullStr |
Silicon isotope variations accompanying basalt weathering in Iceland |
title_full_unstemmed |
Silicon isotope variations accompanying basalt weathering in Iceland |
title_sort |
silicon isotope variations accompanying basalt weathering in iceland |
publishDate |
2016 |
url |
https://doi.org/10.1016/j.epsl.2007.07.004 https://ora.ox.ac.uk/objects/uuid:c7156dbc-211a-46e7-9dcd-d7b7b809b07b |
genre |
Iceland |
genre_facet |
Iceland |
op_relation |
doi:10.1016/j.epsl.2007.07.004 https://ora.ox.ac.uk/objects/uuid:c7156dbc-211a-46e7-9dcd-d7b7b809b07b https://doi.org/10.1016/j.epsl.2007.07.004 |
op_rights |
info:eu-repo/semantics/embargoedAccess |
op_doi |
https://doi.org/10.1016/j.epsl.2007.07.004 |
container_title |
Earth and Planetary Science Letters |
container_volume |
261 |
container_issue |
3-4 |
container_start_page |
476 |
op_container_end_page |
490 |
_version_ |
1766037831726137344 |