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Modern and past processes of ocean-atmosphere-climate interactions in the low-latitude western Pacific and Indian Ocean
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Perturbation of the silicon cycle during the PETM: new insights from silicon isotopes
Wednesday 9th @ 1510-1530, Conference Room 1
Guillaume Fontorbe* , Lund University, Department of Geology, Lund, Sweden
Patrick J. Frings, GFZ Potsdam, Potsdam, Germany
Christina L. De La Rocha,
Katharine R. Hendry, School of Earth Sciences, University of Bristol, Bristol, UK
Daniel J. Conley, Lund University, Department of Geology, Lund, Sweden
Presenter Email: guillaume.fontorbe@geol.lu.se |
| The Paleocene Eocene Thermal Maximum (PETM) is a geologically rapid perturbation of the global carbon cycle that occurred around 56 million years ago, which is marked by a negative carbon isotope excursion (CIE) and an increase in global temperature. The CIE is thought to result from the rapid release of 13C-depleted carbon, however, the source(s) of carbon, the rate of release, internal and/or external triggers, and the mechanisms by which the climate system recovered are still heavily debated. Many of the proposed mechanisms for both onset and recovery of the PETM make testable hypotheses about impacts on the marine silicon cycle, which can potentially be recorded in siliceous microfossils. We analyzed the Si isotopic composition of marine siliceous microfossils covering the PETM and observed a decrease in ¦Ä30Si coeval with the CIE, indicating an immediate response to the silicon cycle during the PETM. Using a simple box model we investigated the sensitivity of oceanic ¦Ä30Si to a set of perturbations in ocean circulation, weathering intensity, and magmatic events; all of which are plausible mechanisms occurring during the PETM. Combining this model with our new Si isotopes record, we provide additional constraints for investigating the processes involved during the different phases of this event. |
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