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Controls on Lithium Incorporation and Isotopic Fractionation in Large Benthic Foraminifera

Charrieau, LM and Rollion-Bard, C and Terbrueggen, A and Wilson, DJ and Pogge von Strandmann, PAE and Misra, S and Bijma, J (2023) Controls on Lithium Incorporation and Isotopic Fractionation in Large Benthic Foraminifera. In: Minerals, 13 (1).

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Official URL: https://doi.org/10.3390/min13010127


The lithium (Li) isotopic composition of carbonates is considered to be a reliable archive of past seawater Li isotopic compositions, which are useful as a tracer of silicate weathering. However, δ7Li values have been shown to be dependent on either pH or DIC in two studies using similar species of large, benthic foraminifera from the genus Amphistegina. To resolve this issue, we conducted culture experiments on Amphistegina lessonii in decoupled pH–DIC conditions, under two different light treatments, and with normal or Li-enriched seawater. The δ7Li values and Li/Ca ratios in the foraminifera tests were analysed by ion microprobe and LA-ICP-MS, respectively. No links between either the pH or DIC and δ7Li or Li/Ca values were observed for any of the treatments, and growth rates also did not seem to influence the Li incorporation or isotopic fractionation, contrary to observations from inorganic carbonate-precipitation experiments. Overall, these findings appear to support the use of Li isotopes in large benthic foraminifera to reconstruct past seawater chemistry and to infer changes in chemical weathering during carbon-cycle perturbations.

Item Type: Journal Article
Publication: Minerals
Publisher: MDPI
Additional Information: The copyright for this article belongs to the Authors.
Keywords: culture experiments; DIC; geochemical proxies; large benthic foraminifera; Li/Ca; lithium; pH; δ7Li
Department/Centre: Division of Mechanical Sciences > Centre for Earth Sciences
Date Deposited: 10 Feb 2023 04:26
Last Modified: 10 Feb 2023 04:26
URI: https://eprints.iisc.ac.in/id/eprint/80141

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