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Understanding the relationship between foraminiferal Mg/Ca and clumped isotope thermometers

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Titel: Understanding the relationship between foraminiferal Mg/Ca and clumped isotope thermometers
Autoren: Peral, Marion, Caley, Thibaut, Malaizé, Bruno, Extier, Thomas, Rossignol, Linda, Barathieu, Héloïse, Dassié, Émilie, Bassinot, Franck, Blamart, Dominique, Daëron, Mathieu
Weitere Verfasser: Aptel, Florence, Archaeology, Environmental changes & Geo-Chemistry, Chemistry
Quelle: Geochimica et Cosmochimica Acta (0016-7037) (Elsevier BV), 2025-10, Vol. 407, P. 253-264
Verlagsinformationen: Elsevier BV, 2025.
Publikationsjahr: 2025
Schlagwörter: Pleistocene, Paleothermometry, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, Foraminifera, [SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces, environment, Paleothermometry Pleistocene Foraminifera
Beschreibung: Reconstructions of past sea surface temperatures (SSTs) are essential for understanding long-term climate variability, yet different proxy methods can yield divergent results. In this study, we compare Mg/Ca-derived SSTs from Globigerinoides ruber sensu stricto and Trilobatus sacculifer with clumped isotope (Δ 47 ) SSTs measured on G. ruber s.s. from the same core, MD96-2048 (Indian Ocean), covering the last 1.25 million years (Ma). Using the same species and samples allows minimizing ecological and environmental biases. We find that Δ 47 -derived SSTs are systematically colder than Mg/Ca-SSTs prior to 0.4 Ma, while both proxies agree well after this point. This offset is not explained by diagenetic alteration (as assessed via SEM), nor by corrections for seawater salinity, pH, or Mg/Ca composition. The Mg/Ca-SSTs from T. sacculifer are more consistent with Δ 47 -SSTs in the older interval, but do not fully resolve the discrepancy. We found that the apparent Δ 47 -based cooling before 0.4 Ma is not supported by seawater δ 18 O estimates or other climate indicators. Our results suggest that Δ 47 -derived SSTs may be affected by an unknown bias in older intervals, although a combination of multiple factors explored in this study could also contribute to the observed offset.
Publikationsart: Article
Other literature type
Dateibeschreibung: application/pdf
Sprache: English
ISSN: 0016-7037
DOI: 10.1016/j.gca.2025.08.011
Zugangs-URL: https://hal.science/hal-05322418v1/document
https://doi.org/10.1016/j.gca.2025.08.011
https://hal.science/hal-05322418v1
https://biblio.vub.ac.be/vubir/understanding-the-relationship-between-foraminiferal-mgca-and-clumped-isotope-thermometers(bc4ff75b-473d-4998-bdb9-a014ada543e4).html
https://archimer.ifremer.fr/doc/00971/108330/121684.pdf
https://archimer.ifremer.fr/doc/00971/108330/
Rights: CC BY
Dokumentencode: edsair.doi.dedup.....2cb14f3b54fa8c5166489daba0e47d47
Datenbank: OpenAIRE
Beschreibung
Abstract:Reconstructions of past sea surface temperatures (SSTs) are essential for understanding long-term climate variability, yet different proxy methods can yield divergent results. In this study, we compare Mg/Ca-derived SSTs from Globigerinoides ruber sensu stricto and Trilobatus sacculifer with clumped isotope (Δ 47 ) SSTs measured on G. ruber s.s. from the same core, MD96-2048 (Indian Ocean), covering the last 1.25 million years (Ma). Using the same species and samples allows minimizing ecological and environmental biases. We find that Δ 47 -derived SSTs are systematically colder than Mg/Ca-SSTs prior to 0.4 Ma, while both proxies agree well after this point. This offset is not explained by diagenetic alteration (as assessed via SEM), nor by corrections for seawater salinity, pH, or Mg/Ca composition. The Mg/Ca-SSTs from T. sacculifer are more consistent with Δ 47 -SSTs in the older interval, but do not fully resolve the discrepancy. We found that the apparent Δ 47 -based cooling before 0.4 Ma is not supported by seawater δ 18 O estimates or other climate indicators. Our results suggest that Δ 47 -derived SSTs may be affected by an unknown bias in older intervals, although a combination of multiple factors explored in this study could also contribute to the observed offset.
ISSN:00167037
DOI:10.1016/j.gca.2025.08.011