Comments on the origin of dust in East Antarctica for present and ice age conditions |
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| Authors: | A Gaudichel M De Angelis S Joussaume J R Petit Y S Korotkevitch V N Petrov |
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| Institution: | (1) Laboratoire de Microscopie Analytique Appliquée aux Sciences de la Terre, Univ, Paris XII, URA-CNRS 1404, Av. Général de Gaulle, F-94010 Creteil;(2) Laboratoire de Glaciologie et Géophysique de l'Environnement, CNRS, rue Molière, BP 96, F-38402 Saint Martin d'lleres Cedex;(3) Laboratoire de Meteorologie Dynamique, CNRS, 24 rue Lhomond, F-75231 Paris;(4) Arctic and Antaretic Research Institute, 38 Beringa St., 199226 Leningrad, USSR |
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| Abstract: | We have studied the distribution of 327 clay mineral particles retrieved from four Antaretic ice smaples corresponding to present and Last Glacial Maximum (LGM) climate conditions. Illite, chlorite, smectite and kaolinite were identified in all samples. Focusing on kaolinite, because of its use as a possible tracer of low latitude soils, we find a significantly smaller amount for LGM samples while the dust concentration in snow during the LGM was about 30 times higher than for present climate conditions. This can be interpreted as change in the contribution of the Australian source with climate.A second approach was based on the modeling of the desert dust cycle using an Atmospheric General Circulation Model (AGCM) under both present-day and ice age conditions. Unlike mineralogical results, the model suggests the prevalence of the Australian dust source in the deposits over East Antarctica under both present-day and LGM climate conditions. However the model fails to reproduce the strong increase in dust deposits during the LGM. This discrepancy could be partly due to the lack of a higher latitude dust source in the model.The stronger dust input recorded in ice cores for the LGM could be related to an additional active high latitude source (possibly close to South America) overlapping the atmospheric background coming from low latitude areas. |
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| Keywords: | continental dust Antarctica paleo-environment glacial age |
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