Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
Clim. Past, 11, 635-645, 2015
https://doi.org/10.5194/cp-11-635-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
01 Apr 2015
A new approach for modeling Cenozoic oceanic lithium isotope paleo-variations: the key role of climate
N. Vigier1 and Y. Goddéris2 1Laboratoire d'Océanographie de Villefranche, CNRS, UPMC, 06230 Villefranche-sur-Mer, France
2Géosciences Environnement Toulouse, CNRS, Université Paul Sabatier, 31400 Toulouse, France
Abstract. The marine record of ocean lithium isotope composition may provide important information constraining the factors that control continental weathering and how they have varied in the past. However, the equations establishing links between the continental flux of Li to the ocean, the continental Li isotope composition and the ocean Li isotope composition are under-constrained, and their resolution are related to significant uncertainties. In order to partially reduce this uncertainty, we propose a new approach that couples the C and Li cycles, such that our proposed reconstruction of the Cenozoic Li cycle is compatible with the required stability of the exospheric carbon cycle on geological timescales. The results of this exercise show, contrary to expectations, that the Cenozoic evolution of the Li isotope composition of rivers did not necessarily mimic the oceanic δ7Li rise. In contrast, variations in the continental flux of Li to the ocean are demonstrated to play a major role in setting the ocean δ7Li. We also provide evidence that Li storage in secondary phases is an important element of the global Li cycle that cannot be neglected, in particular during the early Cenozoic. Our modeling of the published foraminifera record highlights a close link between soil formation rate and indexes recording the climate evolution during the Cenozoic, such as foraminifera δ18O and pCO2 reconstructions. This leads us to conclude that the Li isotope record does not provide persuasive, unique evidence for erosional forcing of Cenozoic change because it could alternatively be consistent with a climatic control on soil production rates.

Citation: Vigier, N. and Goddéris, Y.: A new approach for modeling Cenozoic oceanic lithium isotope paleo-variations: the key role of climate, Clim. Past, 11, 635-645, https://doi.org/10.5194/cp-11-635-2015, 2015.
Publications Copernicus
Download
Short summary
We develop here a new approach that couples the carbon and lithium cycles for reconstructing the Cenozoic Li isotope record. We show that this record does not provide persuasive, unique evidence for Cenozoic change in erosional forcing as it could, alternatively, be consistent with climatic control on soil production rates. The Li storage in continental secondary phases plays a key role, in particular, during the Early Cenozoic.
We develop here a new approach that couples the carbon and lithium cycles for reconstructing the...
Share