Document Type
Article
Publication Date
9-1-2019
Department
Department of Geological and Mining Engineering and Sciences
Abstract
The global paleointensity database for 65–200 Ma was analyzed using a modified suite of paleointensity quality criteria (QPI) such that the likely reliability of measurements is assessed objectively and as consistently as possible across the diverse data set. This interval was chosen because of dramatic extremes of geomagnetic polarity reversal frequency ranging from greater than 10 reversals per million years in the Jurassic hyperactivity period (155–171 Ma) to effectively zero during the Cretaceous Normal Superchron (CNS; 84–126 Ma). Various attempts to establish a relationship between the strength of Earth's magnetic field and the reversal frequency have been made by previous studies, but no consensus has yet been reached primarily because of large uncertainties in paleointensity estimates and sensitivity of these estimates to data selection approaches. It is critical to overcome this problem because the evolution of the dipole moment is a first order constraint on the behavior of the geodynamo. Here we show that conventional statistical tests and Bayesian changepoint modeling consistently indicate the strongest median/average virtual dipole moment during the CNS. In addition, the CNS and Jurassic hyperactivity period are characterized by the highest and lowest percentage of virtual dipole moments exceeding the overall median for the 65‐ to 200‐Ma interval, respectively. These observations suggest that the superchron dynamo was able to generate stronger fields than the dynamo operating in the frequently reversing regime. While the precise mechanism remains unclear, our results are compatible with the hypothesis that field strength and reversal rate variation are controlled by changes in core‐mantle boundary thermochemical conditions.
Publication Title
JGR Solid Earth
Recommended Citation
Kulakov, E. V.,
Sprain, C. J.,
Doubrovine, P. V.,
Smirnov, A. V.,
Paterson, G. A.,
Hawkins, L.,
Fairchild, L.,
Piispa, E. J.,
&
Biggin, A. J.
(2019).
Analysis of an updated paleointensity database (QPI‐PINT) for 65–200 Ma: Implications for the long‐term history of dipole moment through the mesozoic.
JGR Solid Earth,
124(10), 9999-10022.
http://doi.org/10.1029/2018JB017287
Retrieved from: https://digitalcommons.mtu.edu/michigantech-p/938
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Version
Publisher's PDF
Publisher's Statement
©2019. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Publisher’s version of record: https://doi.org/10.1029/2018JB017287