Articles | Volume 19, issue 4
https://doi.org/10.5194/cp-19-765-2023
© Author(s) 2023. 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-19-765-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
03 Apr 2023
Research article |
| 03 Apr 2023
| 03 Apr 2023
Late Neogene nannofossil assemblages as tracers of ocean circulation and paleoproductivity over the NW Australian shelf
Boris-Theofanis Karatsolis
CORRESPONDING AUTHOR
Department of Earth Sciences, Uppsala University, Uppsala, 752 36,
Sweden
Jorijntje Henderiks
Department of Earth Sciences, Uppsala University, Uppsala, 752 36,
Sweden
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The lower branch of the Atlantic Meridional overturning consists of deep-water currents which flow within North Atlantic basins and deposit sediments known as contourite drifts. Fluctuations in the accumulation and the lithology of these drifts can help us understand deep-ocean circulation during past warm intervals. In this study we investigated the sedimentary archive of the Gardar Drift and identified a weakening in bottom current activity across the latest Miocene climatic warming.
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Marine sediments help us investigate the end of a long period of high ocean productivity that occurred 9 to 3 million years ago. By comparing fossil assemblages of calcifying algae from the Indian and South Atlantic oceans, we found that the dominant, fast-growing species and their ecological prominence determined how and when this period ended in each region, showing that phytoplankton species’ dynamics control large changes in paleoproductivity and carbonate deposition across ocean basins.
Boris-Theofanis Karatsolis, Matthias Sinnesael, Tom Dunkley Jones, Anna Joy Drury, Leah LeVay, Anne Briais, Ross Parnell-Turner, Emma Hanson, Paul N. Pearson, Margaret Morris, Haley Svadlenak, Sidney R. Hemming, Claire E. Jasper, Anita Di Chiara, Sara Satolli, Sarah Friedman, Deepa Dwyer, and Philippe Claeys
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The lower branch of the Atlantic Meridional overturning consists of deep-water currents which flow within North Atlantic basins and deposit sediments known as contourite drifts. Fluctuations in the accumulation and the lithology of these drifts can help us understand deep-ocean circulation during past warm intervals. In this study we investigated the sedimentary archive of the Gardar Drift and identified a weakening in bottom current activity across the latest Miocene climatic warming.
Boris-Theofanis Karatsolis, Joseph D. Asanbe, and Jorijntje Henderiks
J. Micropalaeontol., 45, 475–486, https://doi.org/10.5194/jm-45-475-2026, https://doi.org/10.5194/jm-45-475-2026, 2026
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Marine sediments help us investigate the end of a long period of high ocean productivity that occurred 9 to 3 million years ago. By comparing fossil assemblages of calcifying algae from the Indian and South Atlantic oceans, we found that the dominant, fast-growing species and their ecological prominence determined how and when this period ended in each region, showing that phytoplankton species’ dynamics control large changes in paleoproductivity and carbonate deposition across ocean basins.
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Toweius was among the most widespread and important calcareous nannoplankton groups in the oceans 53 million years ago, playing a key role in the evolutionary transition to another prominent group during the Cenozoic (Reticulofenestra). Using detailed biometric measurements with high-resolution imaging, we describe a distinctive, smaller morphotype of Toweius. Our results indicate that this form evolved gradually through speciation, shedding light on the complex evolutionary dynamics of Toweius.
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Short summary
Ocean circulation around NW Australia plays a key role in regulating the climate in the area and is characterised by seasonal variations in the activity of a major boundary current named the Leeuwin Current. By investigating nannofossils found in sediment cores recovered from the NW Australian shelf, we reconstructed ocean circulation in the warmer-than-present world from 6 to 3.5 Ma, as mirrored by long-term changes in stratification and nutrient availability.
Ocean circulation around NW Australia plays a key role in regulating the climate in the area and...
