Late Pleistocene Climatic Variations at Achenheim, France, Based on a Magnetic Susceptibility and TL Chronology of Loess |
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| Authors: | Denis-Didier Rousseau Ludwig Zöller Jean-Pierre Valet |
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| Institution: | aPaléoenvironnements et Palynologie, Institut des Sciences de l'Evolution—UMR CNRS 5554, Université Montpellier II, case 61, place E. Bataillon, 34095, Montpellier cedex 5, France;bLamont-Doherty Earth Observatory of Columbia University, Palisades, New York, 10964;cForschungsstelle Archäometrie der Heidelberger Akademie der Wissenschaften am Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117, Heidelberg, Germany;dLaboratoire de Géomagnétisme interne et Paléomagnétisme, Institut de Physique du Globe de Paris, tour 24-25, Boite 089, 4 place Jussieu, 75252, Paris cedex 05, France |
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| Abstract: | New field investigations of the Achenheim sequence (Alsace, France) allow for the characterization of variations in the low-field magnetic susceptibility over most of the last climatic cycle, i.e., the past 130,000 yr. New stratigraphic data and thermoluminescence measurements permit reassessment of the previous chronological interpretation of the Upper Pleistocene at Achenheim. A high-resolution analysis of magnetic susceptibility discloses the occurrence of a fine-grained “marker” horizon which was also found recently in another section. This horizon is interpreted as a small-scale dust layer deposited prior to the main interval of loess deposition. The horizon, deposited at the marine isotope stage (MIS) 5/4 boundary, has been found in other loess sequences and is especially prevalent in central Europe. It is characterized by low susceptibility values and a grayish color. New thermoluminescence dates indicate that the loess deposition took place after the MIS 5/4 boundary, i.e., after 70,000 yr. These results are consistent with the Greenland GRIP ice-core dust record which also demonstrates a dusty atmosphere after 72,000 yr ago. On a more regional scale, the Achenheim loess sequence demonstrates a reliable correlation between the western side of the Eurasian loess belt and the dust record of the Greenland ice cores. |
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| Keywords: | magnetic susceptibility loess last climatic cycle Greenland dust thermoluminescence Alsace France |
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