Mg and Li Stable Isotope Ratios of Rocks, Minerals, and Water in an Outlet Glacier of the Greenland Ice Sheet
Magnesium and lithium stable isotope ratios (δ26Mg and δ7Li) have shown promise as tools to elucidate biogeochemical processes both at catchment scales and in deciphering global climate processes. Nevertheless, the controls on riverine Mg and Li isotope ratios are often difficult to determine as a m...
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ftunivcam:oai:www.repository.cam.ac.uk:1810/303499 2024-01-14T10:07:02+01:00 Mg and Li Stable Isotope Ratios of Rocks, Minerals, and Water in an Outlet Glacier of the Greenland Ice Sheet Hindshaw, Ruth S Rickli, Jörg Leuthold, Julien 2019-11-29 application/pdf https://www.repository.cam.ac.uk/handle/1810/303499 https://doi.org/10.17863/CAM.50576 eng eng Frontiers Media SA http://dx.doi.org/10.3389/feart.2019.00316 Frontiers in Earth Science https://www.repository.cam.ac.uk/handle/1810/303499 doi:10.17863/CAM.50576 Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/ 37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3703 Geochemistry 3705 Geology Article 2019 ftunivcam https://doi.org/10.17863/CAM.50576 2023-12-21T23:25:28Z Magnesium and lithium stable isotope ratios (δ26Mg and δ7Li) have shown promise as tools to elucidate biogeochemical processes both at catchment scales and in deciphering global climate processes. Nevertheless, the controls on riverine Mg and Li isotope ratios are often difficult to determine as a myriad of factors can cause fractionation from bulk rock values such as secondary mineral formation and preferential weathering of isotopically distinct mineral phases. Quantifying the relative contribution from carbonate and silicate minerals to the dissolved load of glacierized catchments is particularly crucial for determining the role of chemical weathering in modulating the carbon cycle over glacial-interglacial periods. In this study we report Mg and Li isotope data for water, river sediment, rock, and mineral separates from the Leverett Glacier catchment, West Greenland. We assess whether the silicate mineral contributions to the dissolved load, previously determined using radiogenic Sr, Ca, Nd, and Hf isotopes, are consistent with dissolved Mg and Li isotope data, or whether a carbonate contribution is required as inferred previously for this region. For δ7Li, the average dissolved river water value (+19.2 ± 2.5‰, 2SD) was higher than bedrock, river sediment, and mineral δ7Li values, implying a fractionation process. For δ26Mg, the average dissolved river water value (−0.30 ± 0.14‰, 2SD) was within error of bedrock and river sediment and within the range of mineral δ26Mg values (−1.63 to +0.06‰). The river δ26Mg values are consistent with the mixing of Mg derived from the same mineral phases previously identified from radiogenic isotope measurements as controlling the dissolved load chemistry. Glacier fed rivers previously measured in this region had δ26Mg values ~0.80‰ lower than those measured in the Leverett River which could be caused by a larger contribution from garnet (−1.63‰) dissolution compared to Leverett. This study highlights that dissolved Mg and Li isotope ratios in the Leverett River are ... Article in Journal/Newspaper glacier Greenland Ice Sheet Leverett Glacier Apollo - University of Cambridge Repository Greenland Leverett Glacier ENVELOPE(-147.583,-147.583,-85.633,-85.633) |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3703 Geochemistry 3705 Geology |
spellingShingle |
37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3703 Geochemistry 3705 Geology Hindshaw, Ruth S Rickli, Jörg Leuthold, Julien Mg and Li Stable Isotope Ratios of Rocks, Minerals, and Water in an Outlet Glacier of the Greenland Ice Sheet |
topic_facet |
37 Earth Sciences 3709 Physical Geography and Environmental Geoscience 3703 Geochemistry 3705 Geology |
description |
Magnesium and lithium stable isotope ratios (δ26Mg and δ7Li) have shown promise as tools to elucidate biogeochemical processes both at catchment scales and in deciphering global climate processes. Nevertheless, the controls on riverine Mg and Li isotope ratios are often difficult to determine as a myriad of factors can cause fractionation from bulk rock values such as secondary mineral formation and preferential weathering of isotopically distinct mineral phases. Quantifying the relative contribution from carbonate and silicate minerals to the dissolved load of glacierized catchments is particularly crucial for determining the role of chemical weathering in modulating the carbon cycle over glacial-interglacial periods. In this study we report Mg and Li isotope data for water, river sediment, rock, and mineral separates from the Leverett Glacier catchment, West Greenland. We assess whether the silicate mineral contributions to the dissolved load, previously determined using radiogenic Sr, Ca, Nd, and Hf isotopes, are consistent with dissolved Mg and Li isotope data, or whether a carbonate contribution is required as inferred previously for this region. For δ7Li, the average dissolved river water value (+19.2 ± 2.5‰, 2SD) was higher than bedrock, river sediment, and mineral δ7Li values, implying a fractionation process. For δ26Mg, the average dissolved river water value (−0.30 ± 0.14‰, 2SD) was within error of bedrock and river sediment and within the range of mineral δ26Mg values (−1.63 to +0.06‰). The river δ26Mg values are consistent with the mixing of Mg derived from the same mineral phases previously identified from radiogenic isotope measurements as controlling the dissolved load chemistry. Glacier fed rivers previously measured in this region had δ26Mg values ~0.80‰ lower than those measured in the Leverett River which could be caused by a larger contribution from garnet (−1.63‰) dissolution compared to Leverett. This study highlights that dissolved Mg and Li isotope ratios in the Leverett River are ... |
format |
Article in Journal/Newspaper |
author |
Hindshaw, Ruth S Rickli, Jörg Leuthold, Julien |
author_facet |
Hindshaw, Ruth S Rickli, Jörg Leuthold, Julien |
author_sort |
Hindshaw, Ruth S |
title |
Mg and Li Stable Isotope Ratios of Rocks, Minerals, and Water in an Outlet Glacier of the Greenland Ice Sheet |
title_short |
Mg and Li Stable Isotope Ratios of Rocks, Minerals, and Water in an Outlet Glacier of the Greenland Ice Sheet |
title_full |
Mg and Li Stable Isotope Ratios of Rocks, Minerals, and Water in an Outlet Glacier of the Greenland Ice Sheet |
title_fullStr |
Mg and Li Stable Isotope Ratios of Rocks, Minerals, and Water in an Outlet Glacier of the Greenland Ice Sheet |
title_full_unstemmed |
Mg and Li Stable Isotope Ratios of Rocks, Minerals, and Water in an Outlet Glacier of the Greenland Ice Sheet |
title_sort |
mg and li stable isotope ratios of rocks, minerals, and water in an outlet glacier of the greenland ice sheet |
publisher |
Frontiers Media SA |
publishDate |
2019 |
url |
https://www.repository.cam.ac.uk/handle/1810/303499 https://doi.org/10.17863/CAM.50576 |
long_lat |
ENVELOPE(-147.583,-147.583,-85.633,-85.633) |
geographic |
Greenland Leverett Glacier |
geographic_facet |
Greenland Leverett Glacier |
genre |
glacier Greenland Ice Sheet Leverett Glacier |
genre_facet |
glacier Greenland Ice Sheet Leverett Glacier |
op_relation |
https://www.repository.cam.ac.uk/handle/1810/303499 doi:10.17863/CAM.50576 |
op_rights |
Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.17863/CAM.50576 |
_version_ |
1788061446237585408 |