HR: 1340h
AN: PP23B-1340    [Abstracts]
TI: The Rise of Nannoplankton Calcification Correlates With Tectonically-driven Massive Fall of Atmospheric CO2
AU: * Donnadieu, Y
EM: Yannick.Donnadieu@lsce.ipsl.fr
AF: LSCE, CEA-CNRS, Gif-sur-Yvette, 91191, France
AU: Goddéris, Y
EM: godderis@lmtg.obs-mip.fr
AF: LMTG, CNRS-Observatoire, Toulouse, 31000, France
AU: de Vargas, C
EM: vargas@sb-roscoff.fr
AF: Station Biologique de Roscoff, CNRS-Université Pierre et Marie Curie, Roscoff, 29680, France
AU: Pierrehumbert, R
EM: rtp1@geosci.uchicago.edu
AF: Department of Geophysical Sciences, University of Chicago, Chicago, IL 60637, United States
AU: Dromart, G
EM: Gilles.Dromart@ens-lyon.fr
AF: LST, UMR CNRS 5570, Ecole normale supérieure de Lyon & Université Lyon, Lyon, 69000, France
AB: On the basis of a global carbon-climate numerical model, we reconstructed atmospheric carbon dioxide concentrations over the first 60 million years of the Mesozoic. Our analysis indicates that PCO2 declined from more than 3000 ppmv to less than 1000 ppmv, with a drastic drop during the Late Triassic. The fast northward drift of Pangaea exposed a large continental surface to warm and humid equatorial climate, thus promoting CO2 consumption through weathering. This massive drawdown of atmospheric CO2 is consistent with sedimentological and geochemical data of the rock record and correlates with the primary radiation of calcareous nannoplankton, a biological revolution shifting the global carbonate sink from shallow water environments to the open oceans. Our numerical model shows that at time, tectonics, via weathering, increased the pH of the oceanic surface waters by 0.3 units, corresponding to a 50 % decrease in H+ concentration. This may have provided the ultimate environmental trigger which unlocked the newly oxidized Mesozoic open oceans to pelagic nannobiocalcification.
DE: 1600 GLOBAL CHANGE
DE: 1620 Climate dynamics (0429, 3309)
DE: 1622 Earth system modeling (1225)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4950 Paleoecology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting