Rapid grain boundary diffusion in foraminifera tests biases paleotemperature records - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Communications Earth & Environment Année : 2023

Rapid grain boundary diffusion in foraminifera tests biases paleotemperature records

Résumé

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 18 O-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.
Fichier principal
Vignette du fichier
s43247-023-00798-2.pdf (1.6 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)

Dates et versions

hal-04235524 , version 1 (10-10-2023)

Identifiants

Citer

Arthur Adams, Damien Daval, Lukas P Baumgartner, Sylvain Bernard, Torsten Vennemann, et al.. Rapid grain boundary diffusion in foraminifera tests biases paleotemperature records. Communications Earth & Environment, 2023, 4 (1), pp.144. ⟨10.1038/s43247-023-00798-2⟩. ⟨hal-04235524⟩
30 Consultations
13 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More