Rapid grain boundary diffusion in foraminifera tests biases paleotemperature records

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License: CC BY 4.0
Serval ID
serval:BIB_EC16986350DC
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Rapid grain boundary diffusion in foraminifera tests biases paleotemperature records
Journal
Communications Earth & Environment
Author(s)
Adams Arthur, Daval Damien, Baumgartner Lukas P., Bernard Sylvain, Vennemann Torsten, Cisneros-Lazaro Deyanira, Stolarski Jarosław, Baronnet Alain, Grauby Olivier, Guo Jinming, Meibom Anders
ISSN
2662-4435
Publication state
Published
Issued date
27/04/2023
Peer-reviewed
Oui
Volume
4
Number
1
Pages
144
Language
english
Abstract
The oxygen isotopic compositions of fossil foraminifera tests constitute a continuous proxy record of deep-ocean and sea-surface temperatures spanning the last 120 million years. Here, by incubating foraminifera tests in 18O-enriched artificial seawater analogues, we demonstrate that the oxygen isotopic composition of optically translucent, i.e., glassy, fossil foraminifera calcite tests can be measurably altered at low temperatures through rapid oxygen grain-boundary diffusion without any visible ultrastructural changes. Oxygen grain boundary diffusion occurs sufficiently fast in foraminifera tests that, under normal upper oceanic sediment conditions, their grain boundaries will be in oxygen isotopic equilibrium with the surrounding pore fluids on a time scale of <100 years, resulting in a notable but correctable bias of the paleotemperature record. When applied to paleotemperatures from 38,400 foraminifera tests used in paleoclimate reconstructions, grain boundary diffusion can be shown to bias prior paleotemperature estimates by as much as +0.86 to −0.46 °C. The process is general and grain boundary diffusion corrections can be applied to other polycrystalline biocarbonates composed of small nanocrystallites (<100 nm), such as those produced by corals, brachiopods, belemnites, and molluscs, the fossils of which are all highly susceptible to the effects of grain boundary diffusion.
Keywords
General Earth and Planetary Sciences, General Environmental Science
Open Access
Yes
Create date
02/05/2023 12:41
Last modification date
06/05/2023 6:16
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