Quantitative estimates of average geomagnetic axial dipole dominance in deep geological time

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Authors

Andrew Biggin , Richard Bono, Domenico Giovanni Meduri, Courtney Sprain, Christopher J. Davies , Richard Holme, Pavel Doubrovine

Abstract

A defining characteristic of the recent geomagnetic field is its dominant axial dipole which provides its navigational utility and dictates the shape of the magnetosphere. Going back through time, much less is known about the degree of axial dipole dominance. Here we use a substantial and diverse set of 3D numerical dynamo simulations and recent observation-based field models to derive a power law relationship between the angular dispersion of virtual geomagnetic poles at the equator and the median axial dipole dominance measured at Earth’s surface. Applying this relation to published estimates of equatorial angular dispersion implies that geomagnetic axial dipole dominance averaged over 107-109 years has remained moderately high and stable through large parts of geological time. This provides an observational constraint to future studies of the geodynamo and palaeomagnetosphere. It also provides some reassurance as to the reliability of palaeogeographical reconstructions provided by palaeomagnetism.

DOI

https://doi.org/10.31223/osf.io/9s7y6

Subjects

Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics

Keywords

Dates

Published: 2020-08-20 08:53

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License

CC BY Attribution 4.0 International

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