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Meteoric smoke fallout over the Holocene epoch revealed by iridium and platinum in Greenland ice. (Articolo in rivista)

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Meteoric smoke fallout over the Holocene epoch revealed by iridium and platinum in Greenland ice. (Articolo in rivista) (literal)

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P. Gabrielli, C. Barbante, J.M.C. Plane, A. Varga, S. Hong, G. Cozzi, V. Gaspari, F.A. M. Planchon, W. Cairns, C. Ferrari, P. Crutzen, P. Cescon, C.F. Boutron (2004)
Meteoric smoke fallout over the Holocene epoch revealed by iridium and platinum in Greenland ice.
in Nature (Lond.)
(literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

P. Gabrielli, C. Barbante, J.M.C. Plane, A. Varga, S. Hong, G. Cozzi, V. Gaspari, F.A. M. Planchon, W. Cairns, C. Ferrari, P. Crutzen, P. Cescon, C.F. Boutron (literal)

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Laboratoire de Glaciologie et Geophysique de l'Environnement (UMR CNRS/Universite´ Joseph Fourier 5183), 54, rue Moliere, BP 96, 38402 St Martin d'Heres cedex, France Institute for the Dynamics of Environmental Processes-CNR, 30123 Venice, Italy Department of Environmental Sciences, University of Venice, Ca' Foscari, 30123 Venice, Italy School of Environmental Sciences, University of East Anglia, Norwich NR47TJ, UK Korea Polar Research Institute, Korea Ocean Research & Development Institute, Ansan, PO Box 29, Seoul 425-600, Korea Ecole Polytechnique Universitaire de Grenoble (Institut Universitaire de France), Universite Joseph Fourier, 28 avenue Beno?^t Frachon, BP 53, 38041 Grenoble, France Max Planck Institute for Chemistry, Atmospheric Division, Joh.-J.-Becher-Weg 27, 55128 Mainz, Germany Unite de Formation et de Recherche de Physique et Observatoire des Sciences de l'Univers (Institut Universitaire de France), Universite´ Joseph Fourier, Domaine Universitaire, BP 68, 38041, Grenoble, France (literal)

Titolo

Meteoric smoke fallout over the Holocene epoch revealed by iridium and platinum in Greenland ice. (literal)

Abstract

An iridium anomaly at the Cretaceous/Tertiary boundary layer has been attributed to an extraterrestrial body that struck the Earth some 65 million years ago. It has been suggested that, during this event, the carrier of iridium was probably a micrometre-sized silicate-enclosed aggregate or the nanophase material of the vaporized impactor. But the fate of platinum-group elements (such as iridium) that regularly enter the atmosphere via ablating meteoroids remains largely unknown. Here we report a record of iridium and platinum fluxes on a climatic-cycle timescale, back to 128,000 years ago, from a Greenland ice core4. We find that unexpectedly constant fallout of extraterrestrial matter to Greenland occurred during the Holocene, whereas a greatly enhanced input of terrestrial iridium and platinum masked the cosmic flux in the dust-laden atmosphere of the last glacial age. We suggest that nanometresized meteoric smoke particles5,6, formed from the recondensation of ablated meteoroids in the atmosphere at altitudes >70 kilometres, are transported into the winter polar vortices by the mesospheric meridional circulation7 and are preferentially deposited in the polar ice caps. This implies an average global fallout of 14 6 5 kilotons per year of meteoric smoke during the Holocene. (literal)

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