Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Geophysical Research: Solid Earth
Paleomagnetism from the continental geological record is the only quantitative tool for uncovering pre-Mesozoic continent positions. It is crucial for studying geodynamics across deep time and understanding paleoclimate and life evolution. Yet, Earth’s tectonic shifts make older rock samples rare, limiting the available ancient-rock datasets. Additionally, rocks often undergo remagnetization, where their original magnetic signature is lost, a phenomenon that is more likely to have occurred in older rocks, simply because they had more chances.
Previous paleomagnetic records 820 to 780 million years ago, revealed remarkable directional variations, incompatible with stable tectonics and geomagnetic field. Such variable datasets were attributed to rapid true polar wander, or anomalous non-axial dipole and/or hyper-reversing geomagnetic field.
Tonti-Filippini et al. [2024] conducted an exhaustive paleomagnetic analysis on over a thousand samples within an 85-meter stratigraphic sequence spanning approximately 5 million years to around 800 million years ago. This meticulous study showcased the ability to recover a subtly original magnetization in rocks subject to multiple remagnetization events.
The recovered primary magnetization is better explained by the geocentric axial dipole (GAD) hypothesis and plate tectonic speeds and processes akin to present day. It eliminates the necesity of rapid true polar wander, abnormal geomagnetic field configurations, or ultra-rapid continental drift during the specified time period.
Citation: Tonti-Filippini, J. A. D., Robert, B., Muller, É., Paul, A. N., Dellefant, F., Wack, M., et al. (2024). Middle Neoproterozoic (Tonian) polar wander of South China: Paleomagnetism and ID-TIMS U-Pb geochronology of the Laoshanya Formation. Journal of Geophysical Research: Solid Earth, 129, e2023JB027634. https://doi.org/10.1029/2023JB027634
—Daniel Pastor-Galán, Associate Editor, JGR: Solid Earth