| Geomagnetic dipole strength and reversal rate over the past two million years. | |
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MedLine Citation:
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PMID: 15944701 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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Independent records of relative magnetic palaeointensity from sediment cores in different areas of the world can be stacked together to extract the evolution of the geomagnetic dipole moment and thus provide information regarding the processes governing the geodynamo. So far, this procedure has been limited to the past 800,000 years (800 kyr; ref. 3), which does not include any geomagnetic reversals. Here we present a composite curve that shows the evolution of the dipole moment during the past two million years. This reconstruction is in good agreement with the absolute dipole moments derived from volcanic lavas, which were used for calibration. We show that, at least during this period, the time-averaged field was higher during periods without reversals but the amplitude of the short-term oscillations remained the same. As a consequence, few intervals of very low intensity, and thus fewer instabilities, are expected during periods with a strong average dipole moment, whereas more excursions and reversals are expected during periods of weak field intensity. We also observe that the axial dipole begins to decay 60-80 kyr before reversals, but rebuilds itself in the opposite direction in only a few thousand years. |
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Authors:
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Jean-Pierre Valet; Laure Meynadier; Yohan Guyodo |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Nature Volume: 435 ISSN: 1476-4687 ISO Abbreviation: Nature Publication Date: 2005 Jun |
Date Detail:
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Created Date: 2005-06-09 Completed Date: 2005-06-21 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0410462 Medline TA: Nature Country: England |
Other Details:
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Languages: eng Pagination: 802-5 Citation Subset: - |
Affiliation:
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Géomagnétisme et Paléomagnétisme (UMR CNRS 7577), Institut de Physique du Globe de Paris, 4 Place Jussieu, 75252 Paris Cedex 05, France. valet@ipgp.jussieu.fr |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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