A volcano has erupted remnants of Earth's primordial magma ocean
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- Fani Maoré, an underwater volcano ~50 km east of the French island of Mayotte, has been erupting chemical traces of material from Earth's primordial magma ocean in its first 100 million years of history.
- The volcano was discovered after a May 2018 earthquake swarm near Mayotte, and eruptions over the following three years drained so much magma that Mayotte sank about 20 centimetres.
- Catherine Chauvel of CNRS in Paris led the analysis using a newly developed ultra-precise technique to measure neodymium isotopes, with University of Cambridge's Claudine Israel as collaborator.
- Fani Maoré lava showed a slightly higher ratio of neodymium-142 to neodymium-144 than Mayotte's older lavas, pointing to a pocket of ancient mantle rich in bridgmanite — a mineral believed to be among the first to crystallize from the molten Earth.
- The findings suggest Earth's mantle was never as thoroughly mixed as many geologists had assumed, offering the first experimental window into how the primordial magma ocean solidified and created early chemical heterogeneity.
- Independent reviewers Tim Johnson (Curtin University), Bernard Bourdon (CNRS Lyon), and Richard Carlson (Carnegie Science) called the analytical precision a "major achievement" and "exciting advance" in earth science.
Why it matters: For decades, geologists assumed Earth's mantle had been churned for so long that no chemical traces of the planet's first 100 million years could survive. This study delivers the first direct sample of that primordial material, overturning that assumption and giving researchers — not just modellers — actual rocks from the Hadean magma ocean to work with.
