Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments

The extraction of a deepwater radiogenic isotope signal from marine sediments is a powerful, though under-exploited, tool for the characterisation of past climates and modes of ocean circulation. The radiogenic and radioactive isotope compositions (Nd, Pb, Th) of ambient deepwater are stored in auth...

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Published in:Chemical Geology
Main Authors: Gutjahr, Marcus, Frank, Martin, Stirling, Claudine H., Klemm, Veronika, Van de Flierdt, Tina, Halliday, Alex N.
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier 2007
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Online Access:https://oceanrep.geomar.de/id/eprint/2558/
https://oceanrep.geomar.de/id/eprint/2558/1/Gutjahr.pdf
https://doi.org/10.1016/j.chemgeo.2007.03.021
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spelling ftoceanrep:oai:oceanrep.geomar.de:2558 2024-09-30T14:39:49+00:00 Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments Gutjahr, Marcus Frank, Martin Stirling, Claudine H. Klemm, Veronika Van de Flierdt, Tina Halliday, Alex N. 2007 text https://oceanrep.geomar.de/id/eprint/2558/ https://oceanrep.geomar.de/id/eprint/2558/1/Gutjahr.pdf https://doi.org/10.1016/j.chemgeo.2007.03.021 en eng Elsevier https://oceanrep.geomar.de/id/eprint/2558/1/Gutjahr.pdf Gutjahr, M. , Frank, M. , Stirling, C. H., Klemm, V., Van de Flierdt, T. and Halliday, A. N. (2007) Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments. Chemical Geology, 242 . pp. 351-370. DOI 10.1016/j.chemgeo.2007.03.021 <https://doi.org/10.1016/j.chemgeo.2007.03.021>. doi:10.1016/j.chemgeo.2007.03.021 info:eu-repo/semantics/restrictedAccess Article PeerReviewed 2007 ftoceanrep https://doi.org/10.1016/j.chemgeo.2007.03.021 2024-09-04T05:04:40Z The extraction of a deepwater radiogenic isotope signal from marine sediments is a powerful, though under-exploited, tool for the characterisation of past climates and modes of ocean circulation. The radiogenic and radioactive isotope compositions (Nd, Pb, Th) of ambient deepwater are stored in authigenic Fe–Mn oxyhydroxide coatings in marine sediments, but the unambiguous separation of the isotopic signal in this phase from other sedimentary components is difficult and measures are needed to ensure its seawater origin. Here the extracted Fe–Mn oxyhydroxide phase is investigated geochemically and isotopically in order to constrain the potential and the limitations of the reconstruction of deepwater radiogenic isotope compositions from marine sediments. Our results show that the isotope compositions of elements such as Sr and Os obtained from the Fe–Mn oxyhydroxide fraction are easily disturbed by detrital contributions originating from the extraction process, whereas the seawater isotope compositions of Nd, Pb and Th can be reliably extracted from marine sediments in the North Atlantic. The main reason is that the Nd, Pb and Th concentrations in the detrital phase of pelagic sediments are much lower than in the Fe–Mn oxyhydroxide fractions. This is reflected in Al/Nd, Al/Pb and Al/Th ratios of the Fe–Mn oxyhydroxide fractions, which are as low as or even lower than those of hydrogenetic ferromanganese crusts. Mass balance calculations illustrate that the use of the 87Sr/86Sr isotope composition to confirm the seawater origin of the extracted Nd, Pb and Th isotope signals is misleading. Even though the 87Sr/86Sr in the Fe–Mn oxyhydroxide fractions is often higher than the seawater Sr isotope composition, the corresponding detrital contribution does not translate into altered seawater Nd, Pb and Th isotope compositions due to mass balance constraints. Overall the rare earth element patterns, elemental ratios, as well as the mass balance calculations presented here highlight the potential of using authigenic Fe–Mn ... Article in Journal/Newspaper North Atlantic OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Chemical Geology 242 3-4 351 370
institution Open Polar
collection OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel)
op_collection_id ftoceanrep
language English
description The extraction of a deepwater radiogenic isotope signal from marine sediments is a powerful, though under-exploited, tool for the characterisation of past climates and modes of ocean circulation. The radiogenic and radioactive isotope compositions (Nd, Pb, Th) of ambient deepwater are stored in authigenic Fe–Mn oxyhydroxide coatings in marine sediments, but the unambiguous separation of the isotopic signal in this phase from other sedimentary components is difficult and measures are needed to ensure its seawater origin. Here the extracted Fe–Mn oxyhydroxide phase is investigated geochemically and isotopically in order to constrain the potential and the limitations of the reconstruction of deepwater radiogenic isotope compositions from marine sediments. Our results show that the isotope compositions of elements such as Sr and Os obtained from the Fe–Mn oxyhydroxide fraction are easily disturbed by detrital contributions originating from the extraction process, whereas the seawater isotope compositions of Nd, Pb and Th can be reliably extracted from marine sediments in the North Atlantic. The main reason is that the Nd, Pb and Th concentrations in the detrital phase of pelagic sediments are much lower than in the Fe–Mn oxyhydroxide fractions. This is reflected in Al/Nd, Al/Pb and Al/Th ratios of the Fe–Mn oxyhydroxide fractions, which are as low as or even lower than those of hydrogenetic ferromanganese crusts. Mass balance calculations illustrate that the use of the 87Sr/86Sr isotope composition to confirm the seawater origin of the extracted Nd, Pb and Th isotope signals is misleading. Even though the 87Sr/86Sr in the Fe–Mn oxyhydroxide fractions is often higher than the seawater Sr isotope composition, the corresponding detrital contribution does not translate into altered seawater Nd, Pb and Th isotope compositions due to mass balance constraints. Overall the rare earth element patterns, elemental ratios, as well as the mass balance calculations presented here highlight the potential of using authigenic Fe–Mn ...
format Article in Journal/Newspaper
author Gutjahr, Marcus
Frank, Martin
Stirling, Claudine H.
Klemm, Veronika
Van de Flierdt, Tina
Halliday, Alex N.
spellingShingle Gutjahr, Marcus
Frank, Martin
Stirling, Claudine H.
Klemm, Veronika
Van de Flierdt, Tina
Halliday, Alex N.
Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments
author_facet Gutjahr, Marcus
Frank, Martin
Stirling, Claudine H.
Klemm, Veronika
Van de Flierdt, Tina
Halliday, Alex N.
author_sort Gutjahr, Marcus
title Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments
title_short Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments
title_full Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments
title_fullStr Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments
title_full_unstemmed Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments
title_sort reliable extraction of a deepwater trace metal isotope signal from fe-mn oxyhydroxide coatings of marine sediments
publisher Elsevier
publishDate 2007
url https://oceanrep.geomar.de/id/eprint/2558/
https://oceanrep.geomar.de/id/eprint/2558/1/Gutjahr.pdf
https://doi.org/10.1016/j.chemgeo.2007.03.021
genre North Atlantic
genre_facet North Atlantic
op_relation https://oceanrep.geomar.de/id/eprint/2558/1/Gutjahr.pdf
Gutjahr, M. , Frank, M. , Stirling, C. H., Klemm, V., Van de Flierdt, T. and Halliday, A. N. (2007) Reliable extraction of a deepwater trace metal isotope signal from Fe-Mn oxyhydroxide coatings of marine sediments. Chemical Geology, 242 . pp. 351-370. DOI 10.1016/j.chemgeo.2007.03.021 <https://doi.org/10.1016/j.chemgeo.2007.03.021>.
doi:10.1016/j.chemgeo.2007.03.021
op_rights info:eu-repo/semantics/restrictedAccess
op_doi https://doi.org/10.1016/j.chemgeo.2007.03.021
container_title Chemical Geology
container_volume 242
container_issue 3-4
container_start_page 351
op_container_end_page 370
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