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4h ago

Study Finds Deep Mantle ‘Blobs’ Shaped Earth’s Magnetic Field for Hundreds of Millions of Years

Geodynamo simulations matched with paleomagnetic records point to strong heat contrasts at the core–mantle boundary.

image: ©Rost-9D | iStock
Image
Two enormous blobs of solid, superheated material located at the base of Earth’s mantle affect the underlying liquid outer core. Image credit: Biggin et al., doi: 10.1038/s41561-025-01910-1.

Overview

  • Researchers identify two continent-sized, ultrahot solid structures about 2,900 kilometers down beneath Africa and the Pacific, each encircled by a pole-to-pole ring of cooler rock.
  • Numerical models reproduce key features of the magnetic field over roughly 265 million years, linking deep mantle heterogeneity to long-lived patterns and regional shifts.
  • Results indicate that liquid iron flow at the top of the outer core slows or stagnates beneath the hotter regions, leaving persistent imprints on the field.
  • The work challenges the common assumption that long-term averages of the field behave like a perfect dipole aligned with Earth’s rotation, affecting interpretations of paleogeography, climate, paleobiology, and resource formation.
  • The peer-reviewed study, led by the University of Liverpool’s DEEP group with the University of Leeds and published in Nature Geoscience, relied on extensive supercomputing to simulate geological timescales.