Authigenic Pb isotopes from the Laurentian Fan: Changes in chemical weathering and patterns of North American freshwater runoff during the last deglaciation
Climate-dependent chemical weathering trends have a strong impact on the dissolved Pb isotopic composition of continental runoff during glacial terminations, so that this tracer can be used to reconstruct the impact of the North American deglaciation on aspects of freshwater runoff and ocean chemist...
Published in: | Earth and Planetary Science Letters |
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Online Access: | https://oceanrep.geomar.de/id/eprint/21251/ https://oceanrep.geomar.de/id/eprint/21251/1/Kurzweil.pdf https://doi.org/10.1016/j.epsl.2010.09.031 |
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ftoceanrep:oai:oceanrep.geomar.de:21251 2023-05-15T16:41:31+02:00 Authigenic Pb isotopes from the Laurentian Fan: Changes in chemical weathering and patterns of North American freshwater runoff during the last deglaciation Kurzweil, Florian Gutjahr, Marcus Vance, Derek Keigwin, Lloyd 2010 text https://oceanrep.geomar.de/id/eprint/21251/ https://oceanrep.geomar.de/id/eprint/21251/1/Kurzweil.pdf https://doi.org/10.1016/j.epsl.2010.09.031 en eng Elsevier https://oceanrep.geomar.de/id/eprint/21251/1/Kurzweil.pdf Kurzweil, F., Gutjahr, M. , Vance, D. and Keigwin, L. (2010) Authigenic Pb isotopes from the Laurentian Fan: Changes in chemical weathering and patterns of North American freshwater runoff during the last deglaciation. Earth and Planetary Science Letters, 299 (3-4). pp. 458-465. DOI 10.1016/j.epsl.2010.09.031 <https://doi.org/10.1016/j.epsl.2010.09.031>. doi:10.1016/j.epsl.2010.09.031 Article PeerReviewed 2010 ftoceanrep https://doi.org/10.1016/j.epsl.2010.09.031 2023-04-07T15:09:13Z Climate-dependent chemical weathering trends have a strong impact on the dissolved Pb isotopic composition of continental runoff during glacial terminations, so that this tracer can be used to reconstruct the impact of the North American deglaciation on aspects of freshwater runoff and ocean chemistry. Here we present authigenic Fe–Mn oxyhydroxide-derived Pb isotope records from lower Laurentian Fan sediments that trace the local deglacial continental runoff signal through the Gulf of St. Lawrence. We use these records to investigate changes in the Pb isotopic composition of the North American runoff, and their relationship to deglacial processes. The new Pb isotope records are very similar to those from the subtropical deep NW Atlantic locations, though the new data are at higher resolution and exhibit much greater amplitudes of change due to their Laurentide Ice Sheet-proximal setting. Unradiogenic compositions (206Pb/204Pb as low as 18.8 at 18.5 ka) during the latest glacial change towards highly radiogenic compositions during the early Holocene (206Pb/204Pb = 20.1 at 11.2 ka). Late Holocene 206Pb/204Pb values return to intermediate values around 206Pb/204Pb = 19.6. These new data support previous inferences that the Pb isotopic composition of the deep Atlantic is controlled during deglaciation by changes in the pattern and intensity of continental chemical weathering. In more detail, the most significant change in the entire Pb isotope record starts at 12.5 ka and lasts until about 11 ka. This observation, of strong Pb isotopic changes across a climatically cold period in the North Atlantic region, suggests that at this location Pb isotopic compositions recorded in deep marine authigenic Fe–Mn oxyhydroxides not only trace deglacial changes in chemical weathering intensity but also highly depend on major freshwater runoff routes in interior North America. Our data suggest a gradual opening of the eastward freshwater runoff route in the course of the Younger Dryas. Article in Journal/Newspaper Ice Sheet North Atlantic OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Earth and Planetary Science Letters 299 3-4 458 465 |
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Open Polar |
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OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
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ftoceanrep |
language |
English |
description |
Climate-dependent chemical weathering trends have a strong impact on the dissolved Pb isotopic composition of continental runoff during glacial terminations, so that this tracer can be used to reconstruct the impact of the North American deglaciation on aspects of freshwater runoff and ocean chemistry. Here we present authigenic Fe–Mn oxyhydroxide-derived Pb isotope records from lower Laurentian Fan sediments that trace the local deglacial continental runoff signal through the Gulf of St. Lawrence. We use these records to investigate changes in the Pb isotopic composition of the North American runoff, and their relationship to deglacial processes. The new Pb isotope records are very similar to those from the subtropical deep NW Atlantic locations, though the new data are at higher resolution and exhibit much greater amplitudes of change due to their Laurentide Ice Sheet-proximal setting. Unradiogenic compositions (206Pb/204Pb as low as 18.8 at 18.5 ka) during the latest glacial change towards highly radiogenic compositions during the early Holocene (206Pb/204Pb = 20.1 at 11.2 ka). Late Holocene 206Pb/204Pb values return to intermediate values around 206Pb/204Pb = 19.6. These new data support previous inferences that the Pb isotopic composition of the deep Atlantic is controlled during deglaciation by changes in the pattern and intensity of continental chemical weathering. In more detail, the most significant change in the entire Pb isotope record starts at 12.5 ka and lasts until about 11 ka. This observation, of strong Pb isotopic changes across a climatically cold period in the North Atlantic region, suggests that at this location Pb isotopic compositions recorded in deep marine authigenic Fe–Mn oxyhydroxides not only trace deglacial changes in chemical weathering intensity but also highly depend on major freshwater runoff routes in interior North America. Our data suggest a gradual opening of the eastward freshwater runoff route in the course of the Younger Dryas. |
format |
Article in Journal/Newspaper |
author |
Kurzweil, Florian Gutjahr, Marcus Vance, Derek Keigwin, Lloyd |
spellingShingle |
Kurzweil, Florian Gutjahr, Marcus Vance, Derek Keigwin, Lloyd Authigenic Pb isotopes from the Laurentian Fan: Changes in chemical weathering and patterns of North American freshwater runoff during the last deglaciation |
author_facet |
Kurzweil, Florian Gutjahr, Marcus Vance, Derek Keigwin, Lloyd |
author_sort |
Kurzweil, Florian |
title |
Authigenic Pb isotopes from the Laurentian Fan: Changes in chemical weathering and patterns of North American freshwater runoff during the last deglaciation |
title_short |
Authigenic Pb isotopes from the Laurentian Fan: Changes in chemical weathering and patterns of North American freshwater runoff during the last deglaciation |
title_full |
Authigenic Pb isotopes from the Laurentian Fan: Changes in chemical weathering and patterns of North American freshwater runoff during the last deglaciation |
title_fullStr |
Authigenic Pb isotopes from the Laurentian Fan: Changes in chemical weathering and patterns of North American freshwater runoff during the last deglaciation |
title_full_unstemmed |
Authigenic Pb isotopes from the Laurentian Fan: Changes in chemical weathering and patterns of North American freshwater runoff during the last deglaciation |
title_sort |
authigenic pb isotopes from the laurentian fan: changes in chemical weathering and patterns of north american freshwater runoff during the last deglaciation |
publisher |
Elsevier |
publishDate |
2010 |
url |
https://oceanrep.geomar.de/id/eprint/21251/ https://oceanrep.geomar.de/id/eprint/21251/1/Kurzweil.pdf https://doi.org/10.1016/j.epsl.2010.09.031 |
genre |
Ice Sheet North Atlantic |
genre_facet |
Ice Sheet North Atlantic |
op_relation |
https://oceanrep.geomar.de/id/eprint/21251/1/Kurzweil.pdf Kurzweil, F., Gutjahr, M. , Vance, D. and Keigwin, L. (2010) Authigenic Pb isotopes from the Laurentian Fan: Changes in chemical weathering and patterns of North American freshwater runoff during the last deglaciation. Earth and Planetary Science Letters, 299 (3-4). pp. 458-465. DOI 10.1016/j.epsl.2010.09.031 <https://doi.org/10.1016/j.epsl.2010.09.031>. doi:10.1016/j.epsl.2010.09.031 |
op_doi |
https://doi.org/10.1016/j.epsl.2010.09.031 |
container_title |
Earth and Planetary Science Letters |
container_volume |
299 |
container_issue |
3-4 |
container_start_page |
458 |
op_container_end_page |
465 |
_version_ |
1766031960619089920 |