Articles | Volume 21, issue 11
https://doi.org/10.5194/cp-21-2283-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/cp-21-2283-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
19 Nov 2025
Research article |
| 19 Nov 2025
| 19 Nov 2025
Increasing opal productivity in the Late Eocene Southern Ocean: Evidence for increased carbon export preceding the Eocene-Oligocene glaciation
Volkan Özen
CORRESPONDING AUTHOR
Freie Universität Berlin, Institute for Geological Sciences, Malteserstraße 74–100, 12249 Berlin, Germany
Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115 Berlin, Germany
Johan Renaudie
Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115 Berlin, Germany
David Lazarus
Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115 Berlin, Germany
Gabrielle Rodrigues de Faria
Freie Universität Berlin, Institute for Geological Sciences, Malteserstraße 74–100, 12249 Berlin, Germany
Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115 Berlin, Germany
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Clim. Past, 21, 1431–1441, https://doi.org/10.5194/cp-21-1431-2025, https://doi.org/10.5194/cp-21-1431-2025, 2025
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We examine trends in biosiliceous fluxes and isotopic records in the North and South Atlantic, South Pacific, and Indian oceans during two climatic and biotic events: the Latest Danian Event (LDE; ~62.2 Ma) and the Early Late Palaeocene Event (ELPE; ~59.2 Ma). Our results show a peak during the LDE and following the ELPE.
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Biogeosciences, 22, 3029–3046, https://doi.org/10.5194/bg-22-3029-2025, https://doi.org/10.5194/bg-22-3029-2025, 2025
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The synthesis of Palaeogene deep-sea diatom-bearing sediment occurrences indicates that the deposition of diatom-bearing sediments is mainly controlled by nutrient availability and ocean circulation in the Atlantic, Pacific, and Indian oceans. Comparison with shallow marine diatomites suggests that the peak in the number of diatom-bearing sites in the Atlantic is indirectly related to tectonic reorganizations that caused the cessation of shallow marine diatomite deposition between ~46 and ~44 Ma.
Lukas Jonkers, Tonke Strack, Montserrat Alonso-Garcia, Simon D'haenens, Robert Huber, Michal Kucera, Iván Hernández-Almeida, Chloe L. C. Jones, Brett Metcalfe, Rajeev Saraswat, Lóránd Silye, Sanjay K. Verma, Muhamad Naim Abd Malek, Gerald Auer, Cátia F. Barbosa, Maria A. Barcena, Karl-Heinz Baumann, Flavia Boscolo-Galazzo, Joeven Austine S. Calvelo, Lucilla Capotondi, Martina Caratelli, Jorge Cardich, Humberto Carvajal-Chitty, Markéta Chroustová, Helen K. Coxall, Renata M. de Mello, Anne de Vernal, Paula Diz, Kirsty M. Edgar, Helena L. Filipsson, Ángela Fraguas, Heather L. Furlong, Giacomo Galli, Natalia L. García Chapori, Robyn Granger, Jeroen Groeneveld, Adil Imam, Rebecca Jackson, David Lazarus, Julie Meilland, Marína Molčan Matejová, Raphael Morard, Caterina Morigi, Sven N. Nielsen, Diana Ochoa, Maria Rose Petrizzo, Andrés S. Rigual-Hernández, Marina C. Rillo, Matthew L. Staitis, Gamze Tanık, Raúl Tapia, Nishant Vats, Bridget S. Wade, and Anna E. Weinmann
J. Micropalaeontol., 44, 145–168, https://doi.org/10.5194/jm-44-145-2025, https://doi.org/10.5194/jm-44-145-2025, 2025
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Our study provides guidelines improving the reuse of marine microfossil assemblage data, which are valuable for understanding past ecosystems and environmental change. Based on a survey of 113 researchers, we identified key data attributes required for effective reuse. Analysis of a selection of datasets available online reveals a gap between the attributes scientists consider essential and the data currently available, highlighting the need for clearer data documentation and sharing practices.
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Biogeosciences, 22, 1929–1946, https://doi.org/10.5194/bg-22-1929-2025, https://doi.org/10.5194/bg-22-1929-2025, 2025
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We provide a new compilation of rates at which sediments deposited in the deep sea over the last 70 million years. We highlight a bias, linked to the drilling process, that makes it more likely for high rates to be recovered for younger sediments than for older ones. Correcting for this bias, the record shows, contrary to prior estimates, a more stable history, thus providing some insights on the past mismatch between physico-chemical model estimates and observations.
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Clim. Past, 20, 2629–2644, https://doi.org/10.5194/cp-20-2629-2024, https://doi.org/10.5194/cp-20-2629-2024, 2024
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A global-scale compilation of Palaeogene diatomite occurrences shows how palaeogeographic and palaeoceanographic changes impacted diatom accumulation, especially in the middle Eocene. Diatomite deposition dropped in epicontinental seas between ~ 46 and ~ 44 Ma, while diatom accumulation began around 43.5 Ma in open-ocean settings. The compilation also shows an indirect correlation between Palaeogene climate fluctuations and diatomite deposition in shallow-marine and freshwater environments.
Gabrielle Rodrigues de Faria, David Lazarus, Johan Renaudie, Jessica Stammeier, Volkan Özen, and Ulrich Struck
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Export productivity is part of the global carbon cycle, influencing the climate system via biological pump. About 34 million years ago, the Earth's climate experienced a climate transition from a greenhouse state to an icehouse state with the onset of ice sheets in Antarctica. Our study shows important productivity events in the Southern Ocean preceding this climatic shift. Our findings strongly indicate that the biological pump potentially played an important role in that past climate change.
Clément Coiffard, Haytham El Atfy, Johan Renaudie, Robert Bussert, and Dieter Uhl
Biogeosciences, 20, 1145–1154, https://doi.org/10.5194/bg-20-1145-2023, https://doi.org/10.5194/bg-20-1145-2023, 2023
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Eighty-million-year-old fossil leaf assemblages suggest a widespread distribution of tropical rainforest in northeastern Africa.
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J. Micropalaeontol., 41, 165–182, https://doi.org/10.5194/jm-41-165-2022, https://doi.org/10.5194/jm-41-165-2022, 2022
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This study evaluates the use of automatic classification using AI on eight closely related radiolarian species of the genus Podocyrtis based on MobileNet CNN. Species belonging to Podocyrtis are useful for middle Eocene biostratigraphy. Numerous images of Podocyrtis species from the tropical Atlantic Ocean were used to train and validate the CNN. An overall accuracy of about 91 % was obtained. Additional Podocyrtis specimens from other ocean realms were used to test the predictive model.
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Short summary
We studied diatom fossils from the Southern Ocean to understand how ocean productivity changed ~40–30 million years ago during a major climate shift marked by the onset of permanent Antarctic glaciation and global cooling. We found striking shifts in diatom productivity, revealing critical changes in ocean circulation and nutrient supply. Our results show how these microscopic organisms may have influenced climate, acting as a geological force that shaped global climate over time.
We studied diatom fossils from the Southern Ocean to understand how ocean productivity changed...
