Krause, Alexander J;
Sluijs, Appy;
Van der Ploeg, Robin;
Lenton, Timothy M;
Pogge von Strandmann, Philip AE;
(2023)
Enhanced clay formation key in sustaining the Middle Eocene Climatic Optimum.
Nature Geoscience
, 16
p. 730.
10.1038/s41561-023-01234-y.
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Abstract
The Middle Eocene Climatic Optimum (around 40 million years ago) was a roughly 400,000-year-long global warming phase associated with an increase in atmospheric CO2 concentrations and deep-ocean acidifcation that interrupted the Eocene’s long-term cooling trend. The unusually long duration, compared with early Eocene global warming phases, is puzzling as temperature-dependent silicate weathering should have provided a negative feedback, drawing down CO2 over this timescale. Here we investigate silicate weathering during this climate warming event by measuring lithium isotope ratios (reported as δ7 Li), which are a tracer for silicate weathering processes, from a suite of open-ocean carbonate-rich sediments. We fnd a positive δ7 Li excursion—the only one identifed for a warming event so far —of ~3‰. Box model simulations support this signal to refect a global shift from congruent weathering, with secondary mineral dissolution, to incongruent weathering, with secondary mineral formation. We surmise that, before the climatic optimum, there was considerable soil shielding of the continents. An increase in continental volcanism initiated the warming event, but it was sustained by an increase in clay formation, which sequestered carbonate-forming cations, short-circuiting the carbonate–silicate cycle. Clay mineral dynamics may play an important role in the carbon cycle for climatic events occurring over intermediate (i.e., 100,000 year) timeframes.
| Type: | Article |
|---|---|
| Title: | Enhanced clay formation key in sustaining the Middle Eocene Climatic Optimum |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1038/s41561-023-01234-y |
| Publisher version: | https://doi.org/10.1038/s41561-023-01234-y |
| Language: | English |
| Additional information: | This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. |
| Keywords: | Carbon cycle, Element cycles, Geochemistry, Palaeoceanography, Palaeoclimate |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10174824 |
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