Omnipresent authigenic calcite distorts Arctic radiocarbon chronology

As calcareous foraminifera precipitate their shells from the surrounding water mass, they are the basis of most marine radiocarbon chronologies and paleo-proxies. Nevertheless, post-mortem alteration of shells, especially addition of authigenic calcite, impact proxy records. In the Arctic Ocean, aut...

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Bibliographic Details
Published in:Communications earth & environment 2023-12, Vol.4 (1), p.136-15, Article 136
Main Authors: Wollenburg, Jutta Erika, Matthiessen, Jens, Vogt, Christoph, Nehrke, Gernot, Grotheer, Hendrik, Wilhelms-Dick, Dorothee, Geibert, Walter, Mollenhauer, Gesine
Format: Article
Language:English
Subjects:
Calcite
Carbon
Carbon 13
Carbon 14
Carbon isotopes
Carbon sources
Chronology
Comparative analysis
Cores
Deglaciation
Glacial periods
Holocene
Isotopes
Oxygen enrichment
Oxygen isotopes
Paleoclimate
Sediments
Shells
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Summary:As calcareous foraminifera precipitate their shells from the surrounding water mass, they are the basis of most marine radiocarbon chronologies and paleo-proxies. Nevertheless, post-mortem alteration of shells, especially addition of authigenic calcite, impact proxy records. In the Arctic Ocean, authigenic calcite overgrowth on foraminifera has been attributed to hydrocarbon release, with a single report on 13 C-enriched authigenic calcite, indicating a different carbon source. Here, we use comparative radiocarbon, carbon and oxygen isotope measurements to show that this 13 C-enriched authigenic calcite impacts a large proportion of Holocene and the majority of last glacial planktonic foraminifera in the Arctic Basin. This authigenic precipitated calcite is 14 C-depleted, so overgrowth results in invariably older 14 C-ages. We show that, in comparison with published data, the true chronology of Arctic basin sediments can deviate by more than 10,000 years in critical parts of the last deglaciation and that stable oxygen and carbon isotopes, as likely all calcite-based proxy-records are affected with potential implications for paleoclimate models.
ISSN:2662-4435
2662-4435
DOI:10.1038/s43247-023-00802-9