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A climatic control on the accretion of meteoric and super-chondritic iridium–platinum to the Antarctic ice cap

Paolo Gabrielli 1, 2 John M.C. Plane 3 Claude F. Boutron 2, 4, 5 Sungmin Hong 6 Giulio Cozzi 7 Paolo Cescon 1, 7 Christophe Ferrari 2, 8 Paul J. Crutzen 9 Jean Robert Petit 2 Vladimir Y. Lipenkov 10 Carlo Barbante 1, 7
1 Institute for the Dynamics of Environmental Processes-CNR
2 LGGE - Laboratoire de glaciologie et géophysique de l'environnement
3 School of Chemistry [Leeds]
4 Unité de Formation et de Recherche de Physique
5 OSUG - Observatoire des Sciences de l'Univers de Grenoble
6 KORDI - Korean Ocean Research and Development Institute
7 Environmental Sciences Department
8 Polytech' Grenoble
9 MPIC - Max Planck Institute for Chemistry
10 AARI - Arctic and Antarctic Research Institute
Abstract : Meteoric smoke particles (MSPs) form through the vaporization of meteoroids and the subsequent re-condensation of metallic species in the mesosphere. Recently, iridium and platinum enrichments have been identified in Greenland ice layers and attributed to the fallout of MSPs supplying polar latitudes with cosmic matter during the Holocene. However, the MSP fallout to Antarctica during the Earth's climatic history remains essentially unknown. We have determined iridium and platinum in deep Antarctic ice from Dome C and Vostok dated back to 240 kyrs BP. We find high super-chondritic fluxes during warm periods and low meteoric accretion during glacial times, a pattern that is opposite to any known climatic variation in dust fallout to polar regions. The proposed explanation of this accretion regime is a weaker polar vortex during warm periods, allowing peripheral air masses enriched in volcanic iridium and platinum to penetrate inland to Antarctica. The MSP signal emerges only during cold phases and is four times lower than in the Greenland ice cap where more snow accumulates. This suggests that wet deposition is an important route of cosmic material to the Earth's surface.
keyword : iridium platinum meteoric smoke ice Antarctica climate
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https://hal-insu.archives-ouvertes.fr/insu-00375474
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Submitted on : Wednesday, April 15, 2009 - 11:00:18 AM
Last modification on : Thursday, November 19, 2020 - 3:54:29 PM

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Paolo Gabrielli, John M.C. Plane, Claude F. Boutron, Sungmin Hong, Giulio Cozzi, et al.. A climatic control on the accretion of meteoric and super-chondritic iridium–platinum to the Antarctic ice cap. Earth and Planetary Science Letters, Elsevier, 2006, 250 (3-4), pp.459 à 469. ⟨10.1016/j.epsl.2006.08.015⟩. ⟨insu-00375474⟩

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