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| Titel |
A new approach for modeling Cenozoic oceanic lithium isotope paleo-variations: the key role of climate |
| VerfasserIn |
N. Vigier, Y. Godderis |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 11, no. 4 ; Nr. 11, no. 4 (2015-04-01), S.635-645 |
| Datensatznummer |
250117256
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| Publikation (Nr.) |
 copernicus.org/cp-11-635-2015.pdf |
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| Zusammenfassung |
| 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. |
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