Deep Earth Structures Influence Magnetic Field, New Research Reveals

New research has identified magnetic evidence indicating that two vast, ultra-hot rock structures situated at the base of Earth's mantle, approximately 2,900 kilometers beneath Africa and the Pacific, influence the underlying liquid outer core.

The study, published in Nature Geoscience and led by the University of Liverpool, indicates that these immense structures, composed of solid, superheated material and surrounded by cooler rock, have been shaping Earth's magnetic field over millions of years.

Unraveling Earth's Deep Secrets

Researchers investigated these deep-Earth features by combining paleomagnetic observations with advanced computer simulations of the geodynamo. The geodynamo is the flow of liquid iron in the outer core responsible for generating Earth's magnetic field.

Numerical models were utilized to reconstruct observations of the magnetic field's behavior over the past 265 million years.

Core Findings Emerge

The findings revealed that the outer core's upper boundary exhibits significant thermal contrasts, with localized hot regions positioned beneath these continent-sized rock structures. It was also observed that certain parts of the magnetic field have remained relatively stable for hundreds of millions of years, while others have undergone substantial changes over time.

"These results suggest strong temperature contrasts within the rocky mantle directly above the core."

Professor Andy Biggin of the University of Liverpool stated that these results suggest strong temperature contrasts within the rocky mantle directly above the core. Beneath hotter regions, liquid iron in the core may stagnate rather than participate in the vigorous flow observed under cooler regions.

Broader Implications for Earth Sciences

These insights into the deep Earth on long timescales support the use of ancient magnetic field records to understand both the dynamic evolution and more stable properties of the deep Earth. The findings also carry implications for understanding ancient continental configurations, such as the formation and breakup of Pangaea, and may help resolve uncertainties in ancient climate, paleobiology, and natural resource formation. They challenge the assumption that Earth's magnetic field, when averaged over long periods, behaved as a perfect bar magnet aligned with the planet's rotational axis.