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| Titel |
Stable runoff and weathering fluxes into the oceans over Quaternary climate cycles |
| VerfasserIn |
Friedhelm von Blanckenburg, Julien Bouchez, Daniel E. Ibarra, Maher Kate |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250128296
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| Publikation (Nr.) |
 EGU/EGU2016-8276.pdf |
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| Zusammenfassung |
| Throughout the Quaternary, erosion and biogeochemical cycles at the Earth surface
responded to large oscillations in temperature and precipitation. Such changes are recorded in
sedimentary archives and radiogenic isotope mass balances. In contrast, climate models
combined with empirical relationships between measures of climate and weatheringindicate
minimal change in global weathering rates. Here we resolve the extent to which the supply of
dissolved elements to oceans was altered by glacial-interglacial oscillations with a new
weathering proxy. We estimate relative weathering fluxes from the ratio of cosmogenic
beryllium-10, produced in the atmosphere, to the stable isotope beryllium-9, introduced into
the oceans by the riverine silicate weathering flux [1]. Using sedimentary Be records,we
show over multiple glacial-interglacial cycles, and over the last 2 Myr, shifts in global silicate
weathering inputs are not detectable [2]. Combining climate model simulations of the Last
Glacial Maximum with a new model for silicate weathering, we show how large regional
variability in runoff between glacial and interglacial periods was insufficient to
shift global weathering fluxes. The observed and modeled stability explains why
removal of atmospheric CO2 by silicate weathering has been balanced to within
2% of net CO2 degassing over the last 600 kyr. Because over >104 yr time scales
weathering and erosion are also coupled, our study provides additional evidence that
global erosion rates did not shift along any long-term trend over the Quaternary
[3].
[1] von Blanckenburg, F. and Bouchez, J. (2014). "River fluxes to the sea from the oceans
10Be/9Be ratio." Earth and Planetary Science Letters 387: 34-43.
[2] von Blanckenburg, F., Bouchez. J. Ibarra, D.E., Maher, K. (2015). "Stable runoff and
weathering fluxes into the oceans over Quaternary climate cycles." Nature Geosciences
10.1038/ngeo2452.
[3] Willenbring, J. K. and von Blanckenburg, F. (2010). "Long-term stability of global
erosion rates and weathering during late-Cenozoic cooling." Nature 465: 211-214. |
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