Did a large departure from the geocentric axial dipole hypothesis occur during the Eocene? Evidence from the magnetic polar wander path of Eurasia

1993 ◽  
Vol 117 (1-2) ◽  
pp. 15-28 ◽  
Author(s):  
Michel Westphal
1996 ◽  
Vol 144 (3-4) ◽  
pp. 337-346 ◽  
Author(s):  
Gary D. Acton ◽  
Katerina E. Petronotis ◽  
Cheryl D. Cape ◽  
Sue Rotto Ilg ◽  
Richard G. Gordon ◽  
...  

2018 ◽  
Vol 215 (3) ◽  
pp. 1523-1529
Author(s):  
Peter Olson ◽  
Maylis Landeau ◽  
Evan Reynolds

SUMMARY A fundamental assumption in palaeomagnetism is that the geomagnetic field closely approximates a geocentric axial dipole in time average. Here we use numerical dynamos driven by heterogeneous core–mantle boundary heat flux from a mantle global circulation model to demonstrate how mantle convection produces true dipole wander, rotation of the geomagnetic dipole on geologic timescales. Our heterogeneous mantle-driven dynamos show a dipole rotation about a near-equatorial axis in response to the transition in lower mantle heterogeneity from a highly asymmetric pattern at the time of supercontinent Pangea to a more symmetric pattern today. This predicted dipole rotation overlaps with a palaeomagnetically inferred rotation in the opposite direction and suggests that some events previously interpreted as true polar wander also include true dipole wander.


2015 ◽  
Vol 112 (49) ◽  
pp. 15036-15041 ◽  
Author(s):  
Huapei Wang ◽  
Dennis V. Kent ◽  
Pierre Rochette

The geomagnetic field is predominantly dipolar today, and high-fidelity paleomagnetic mean directions from all over the globe strongly support the geocentric axial dipole (GAD) hypothesis for the past few million years. However, the bulk of paleointensity data fails to coincide with the axial dipole prediction of a factor-of-2 equator-to-pole increase in mean field strength, leaving the core dynamo process an enigma. Here, we obtain a multidomain-corrected Pliocene–Pleistocene average paleointensity of 21.6 ± 11.0 µT recorded by 27 lava flows from the Galapagos Archipelago near the Equator. Our new result in conjunction with a published comprehensive study of single-domain–behaved paleointensities from Antarctica (33.4 ± 13.9 µT) that also correspond to GAD directions suggests that the overall average paleomagnetic field over the past few million years has indeed been dominantly dipolar in intensity yet only ∼60% of the present-day field strength, with a long-term average virtual axial dipole magnetic moment of the Earth of only 4.9 ± 2.4 × 1022 A⋅m2.


2017 ◽  
Vol 265 ◽  
pp. 54-61 ◽  
Author(s):  
Toni Veikkolainen ◽  
Moritz Heimpel ◽  
Michael E. Evans ◽  
Lauri J. Pesonen ◽  
Kimmo Korhonen

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