A paleointensity test of the Geocentric Axial Dipole (GAD) hypothesis

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http://hdl.handle.net/10138/309174

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Veikkolainen , T H K , Heimpel , M , Evans , M E , Pesonen , L & Korhonen , K 2017 , ' A paleointensity test of the Geocentric Axial Dipole (GAD) hypothesis ' , Physics of the Earth and Planetary Interiors , vol. 265 , pp. 54-61 . https://doi.org/10.1016/j.pepi.2017.02.008

Title: A paleointensity test of the Geocentric Axial Dipole (GAD) hypothesis
Author: Veikkolainen, Toni Henri Kristian; Heimpel, Moritz; Evans, Michael E.; Pesonen, Lauri; Korhonen, Kimmo
Contributor: University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
Date: 2017-04
Language: eng
Number of pages: 8
Belongs to series: Physics of the Earth and Planetary Interiors
ISSN: 0031-9201
URI: http://hdl.handle.net/10138/309174
Abstract: The Geocentric Axial Dipole (GAD) model is central to many aspects of geophysics, including plate tectonics and paleoclimate. But its validity is by no means firmly established, particularly for the Precambrian. One test that has met with some success involves the distribution of paleomagnetic inclination angles. It works because any given field morphology has its own distinct probability distribution function (PDF) against which data compilations can be tested. Here, we investigate a second possible test using published paleointensity data. Once again, any given field morphology has a specific PDF of intensity. Likely field models consist of an underlying GAD on which is superimposed modest zonal quadrupole and octupole components. The corresponding paleointensity PDFs turn out to have more complicated shapes than their inclination counterparts, often having multiple maxima and minima. Given sufficient data, this complexity offers greater discrimination between models. In this paper, the potential of the paleointensity test is assessed using an extension of the PINT paleointensity database. We found it useful to analyze the Phanerozoic and Precambrian intervals separately. Despite the inherent limitations of this kind of analysis, a tripartite geodynamo with small zonal multipoles appears to be a good starting point on a way towards more fine-tuned models.
Subject: 114 Physical sciences
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