Articles | Volume 18, issue 11
https://doi.org/10.5194/cp-18-2509-2022
© Author(s) 2022. 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-18-2509-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
22 Nov 2022
Research article |
| 22 Nov 2022
| 22 Nov 2022
Accurately calibrated X-ray fluorescence core scanning (XRF-CS) record of Ti ∕ Al reveals Early Pleistocene aridity and humidity variability over North Africa and its close relationship to low-latitude insolation
Rick Hennekam
CORRESPONDING AUTHOR
Department of Ocean Systems, NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, the Netherlands
Katharine M. Grant
Research School of Earth Sciences, Australian National University,
Canberra, ACT 2600, Australia
Eelco J. Rohling
Research School of Earth Sciences, Australian National University,
Canberra, ACT 2600, Australia
Ocean and Earth Science, National
Oceanography Centre, University of Southampton, Southampton, SO14 3ZH, UK
Rik Tjallingii
GFZ German Research Centre for Geosciences, Sect. 5.2 – Climate
Dynamics and Landscape Evolution, 14473 Potsdam, Germany
David Heslop
Research School of Earth Sciences, Australian National University,
Canberra, ACT 2600, Australia
Andrew P. Roberts
Research School of Earth Sciences, Australian National University,
Canberra, ACT 2600, Australia
Lucas J. Lourens
Department of Earth Sciences, Faculty of Geosciences, Utrecht
University, P.O. Box 80.121, 3508 TA Utrecht, the Netherlands
Gert-Jan Reichart
Department of Ocean Systems, NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, the Netherlands
Department of Earth Sciences, Faculty of Geosciences, Utrecht
University, P.O. Box 80.121, 3508 TA Utrecht, the Netherlands
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David A. Hodell, Simon J. Crowhurst, Lucas Lourens, Vasiliki Margari, John Nicolson, James E. Rolfe, Luke C. Skinner, Nicola C. Thomas, Polychronis C. Tzedakis, Maryline J. Mleneck-Vautravers, and Eric W. Wolff
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Carolien M. H. van der Weijst, Koen J. van der Laan, Francien Peterse, Gert-Jan Reichart, Francesca Sangiorgi, Stefan Schouten, Tjerk J. T. Veenstra, and Appy Sluijs
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Henry Hooghiemstra, Gustavo Sarmiento Pérez, Vladimir Torres Torres, Juan-Carlos Berrío, Lucas Lourens, and Suzette G. A. Flantua
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Alice E. Webb, Didier M. de Bakker, Karline Soetaert, Tamara da Costa, Steven M. A. C. van Heuven, Fleur C. van Duyl, Gert-Jan Reichart, and Lennart J. de Nooijer
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Anna Joy Drury, Diederik Liebrand, Thomas Westerhold, Helen M. Beddow, David A. Hodell, Nina Rohlfs, Roy H. Wilkens, Mitchell Lyle, David B. Bell, Dick Kroon, Heiko Pälike, and Lucas J. Lourens
Clim. Past, 17, 2091–2117, https://doi.org/10.5194/cp-17-2091-2021, https://doi.org/10.5194/cp-17-2091-2021, 2021
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Indah Ardiningsih, Kyyas Seyitmuhammedov, Sylvia G. Sander, Claudine H. Stirling, Gert-Jan Reichart, Kevin R. Arrigo, Loes J. A. Gerringa, and Rob Middag
Biogeosciences, 18, 4587–4601, https://doi.org/10.5194/bg-18-4587-2021, https://doi.org/10.5194/bg-18-4587-2021, 2021
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Organic Fe speciation is investigated along a natural gradient of the western Antarctic Peninsula from an ice-covered shelf to the open ocean. The two major fronts in the region affect the distribution of ligands. The excess ligands not bound to dissolved Fe (DFe) comprised up to 80 % of the total ligand concentrations, implying the potential to solubilize additional Fe input. The ligands on the shelf can increase the DFe residence time and fuel local primary production upon ice melt.
Cécile L. Blanchet, Rik Tjallingii, Anja M. Schleicher, Stefan Schouten, Martin Frank, and Achim Brauer
Clim. Past, 17, 1025–1050, https://doi.org/10.5194/cp-17-1025-2021, https://doi.org/10.5194/cp-17-1025-2021, 2021
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The Mediterranean Sea turned repeatedly into an oxygen-deprived basin during the geological past, as evidenced by distinct sediment layers called sapropels. We use here records of the last sapropel S1 retrieved in front of the Nile River to explore the relationships between riverine input and seawater oxygenation. We decipher the seasonal cycle of fluvial input and seawater chemistry as well as the decisive influence of primary productivity on deoxygenation at millennial timescales.
Ove H. Meisel, Joshua F. Dean, Jorien E. Vonk, Lukas Wacker, Gert-Jan Reichart, and Han Dolman
Biogeosciences, 18, 2241–2258, https://doi.org/10.5194/bg-18-2241-2021, https://doi.org/10.5194/bg-18-2241-2021, 2021
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Arctic permafrost lakes form thaw bulbs of unfrozen soil (taliks) beneath them where carbon degradation and greenhouse gas production are increased. We analyzed the stable carbon isotopes of Alaskan talik sediments and their porewater dissolved organic carbon and found that the top layers of these taliks are likely more actively degraded than the deeper layers. This in turn implies that these top layers are likely also more potent greenhouse gas producers than the underlying deeper layers.
Bas de Boer, Marit Peters, and Lucas J. Lourens
Clim. Past, 17, 331–344, https://doi.org/10.5194/cp-17-331-2021, https://doi.org/10.5194/cp-17-331-2021, 2021
Delphine Dissard, Gert Jan Reichart, Christophe Menkes, Morgan Mangeas, Stephan Frickenhaus, and Jelle Bijma
Biogeosciences, 18, 423–439, https://doi.org/10.5194/bg-18-423-2021, https://doi.org/10.5194/bg-18-423-2021, 2021
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Results from a data set acquired from living foraminifera T. sacculifer collected from surface waters are presented, allowing us to establish a new Mg/Ca–Sr/Ca–temperature equation improving temperature reconstructions. When combining equations, δ18Ow can be reconstructed with a precision of ± 0.5 ‰, while successive reconstructions involving Mg/Ca and δ18Oc preclude salinity reconstruction with a precision better than ± 1.69. A new direct linear fit to reconstruct salinity could be established.
Siham de Goeyse, Alice E. Webb, Gert-Jan Reichart, and Lennart J. de Nooijer
Biogeosciences, 18, 393–401, https://doi.org/10.5194/bg-18-393-2021, https://doi.org/10.5194/bg-18-393-2021, 2021
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Foraminifera are calcifying organisms that play a role in the marine inorganic-carbon cycle and are widely used to reconstruct paleoclimates. However, the fundamental process by which they calcify remains essentially unknown. Here we use inhibitors to show that an enzyme is speeding up the conversion between bicarbonate and CO2. This helps the foraminifera acquire sufficient carbon for calcification and might aid their tolerance to elevated CO2 level.
Linda K. Dämmer, Lennart de Nooijer, Erik van Sebille, Jan G. Haak, and Gert-Jan Reichart
Clim. Past, 16, 2401–2414, https://doi.org/10.5194/cp-16-2401-2020, https://doi.org/10.5194/cp-16-2401-2020, 2020
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The compositions of foraminifera shells often vary with environmental parameters such as temperature or salinity; thus, they can be used as proxies for these environmental variables. Often a single proxy is influenced by more than one parameter. Here, we show that while salinity impacts shell Na / Ca, temperature has no effect. We also show that the combination of different proxies (Mg / Ca and δ18O) to reconstruct salinity does not seem to work as previously thought.
Anne Roepert, Lubos Polerecky, Esmee Geerken, Gert-Jan Reichart, and Jack J. Middelburg
Biogeosciences, 17, 4727–4743, https://doi.org/10.5194/bg-17-4727-2020, https://doi.org/10.5194/bg-17-4727-2020, 2020
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We investigated, for the first time, the spatial distribution of chlorine and fluorine in the shell walls of four benthic foraminifera species: Ammonia tepida, Amphistegina lessonii, Archaias angulatus, and Sorites marginalis. Cross sections of specimens were imaged using nanoSIMS. The distribution of Cl and F was co-located with organics in the rotaliids and rather homogeneously distributed in miliolids. We suggest that the incorporation is governed by the biomineralization pathway.
Arne Ramisch, Alexander Brauser, Mario Dorn, Cecile Blanchet, Brian Brademann, Matthias Köppl, Jens Mingram, Ina Neugebauer, Norbert Nowaczyk, Florian Ott, Sylvia Pinkerneil, Birgit Plessen, Markus J. Schwab, Rik Tjallingii, and Achim Brauer
Earth Syst. Sci. Data, 12, 2311–2332, https://doi.org/10.5194/essd-12-2311-2020, https://doi.org/10.5194/essd-12-2311-2020, 2020
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Annually laminated lake sediments (varves) record past climate change at seasonal resolution. The VARved sediments DAtabase (VARDA) is created to utilize the full potential of varves for climate reconstructions. VARDA offers free access to a compilation and synchronization of standardized climate-proxy data, with applications ranging from reconstructing regional patterns of past climate change to validating simulations of climate models. VARDA is freely accessible at https://varve.gfz-potsdam.de
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Short summary
The ratio of titanium to aluminum (Ti/Al) is an established way to reconstruct North African climate in eastern Mediterranean Sea sediments. We demonstrate here how to obtain reliable Ti/Al data using an efficient scanning method that allows rapid acquisition of long climate records at low expense. Using this method, we reconstruct a 3-million-year North African climate record. African environmental variability was paced predominantly by low-latitude insolation from 3–1.2 million years ago.
The ratio of titanium to aluminum (Ti/Al) is an established way to reconstruct North African...
