TY  - JOUR
TI  - Enhanced clay formation key in sustaining the Middle Eocene Climatic Optimum
SN  - 1752-0894
AV  - public
EP  - 730
N1  - 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/.
KW  - Carbon cycle
KW  -  Element cycles
KW  -  Geochemistry
KW  -  Palaeoceanography
KW  -  Palaeoclimate
Y1  - 2023/08//
N2  - 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 ?7
Li), which are a tracer for
silicate weathering processes, from a suite of open-ocean carbonate-rich
sediments. We fnd a positive ?7
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.
ID  - discovery10174824
UR  - https://doi.org/10.1038/s41561-023-01234-y
VL  - 16
SP  - 730
JF  - Nature Geoscience
A1  - Krause, Alexander J
A1  - Sluijs, Appy
A1  - Van der Ploeg, Robin
A1  - Lenton, Timothy M
A1  - Pogge von Strandmann, Philip AE
PB  - Springer Science and Business Media LLC
ER  -