Underwater Volcano Coughed Up 4.5-Billion-Year-Old Magma

In May 2018, the island of Mayotte, tucked between Madagascar and Mozambique, started shaking. A lot. The earthquakes eventually led scientists to a brand-new underwater volcano, now called Fani Maoré. They went out, they took samples, and they found something nobody expected: a chemical fingerprint from the very beginning of the planet. The mantle, it turns out, has been holding a grudge for 4.5 billion years.

Around 4.5 billion years ago, during the Hadean eon, a catastrophic collision ejected debris from Earth that coalesced into the moon. That same impact triggered a global magma ocean, and as it cooled, a mineral called bridgmanite crystallized first from the melt. The conventional assumption has been that billions of years of churning mantle convection would have scrambled all of that early material into oblivion. These findings suggest Earth's mantle may never have become as thoroughly mixed as many geologists had assumed.

The key was isotope chemistry. The team used a more precise measurement method developed by Claudine Israel of the University of Cambridge, which revealed a statistically significant positive neodymium-142 anomaly in the lava samples from Fani Maoré. That anomaly is essentially a timestamp: the short-lived parent isotope that produced neodymium-142 disappeared early, so a surviving excess points to material that separated chemically within Earth's first 100 million years.

That elevated ratio likely reflects a pocket of ancient mantle that escaped billions of years of mixing and remains relatively rich in bridgmanite. The researchers' modeling suggests only about 9 to 11 percent of that ancient Hadean component is needed in the deep mantle plume to explain the measured signal.

The Hadean eon was so early and so violent that it left almost no direct physical record. Fani Maoré just handed scientists a piece of it anyway.

Read the full story at Phys.org, July 2026

Hot Take: The mantle was hoarding a 4.5-billion-year-old souvenir from the day the Moon was born. One sneaky young volcano was kind enough to bring it to show and tell.