New Mayotte Volcano Lava Shows Slightly Higher Neodymium-142 Ratio

A new underwater volcano named Fani Maoré, located about 50 km east of Mayotte in the Indian Ocean, has erupted lava carrying chemical signatures from Earth's first 100 million years. An earthquake swarm off Mayotte in May 2018 led researchers to the site, and eruptions over the next three years caused the island to sink roughly 20 cm.

Scientists recovered rock samples from Fani Maoré and the older volcanic system on Mayotte.

Analysis showed the newer lava held a slightly higher ratio of neodymium-142 to neodymium-144. Catherine Chauvel of the French National Centre for Scientific Research said the ratio indicates a pocket of ancient mantle still rich in bridgmanite, a mineral among the first to crystallize from the global magma ocean.

The team used an ultra-precise technique developed with Claudine Israel at the University of Cambridge to measure the isotope differences.

The findings, published in Nature, suggest Earth's mantle never mixed as thoroughly as many models assumed and still preserves material dating back approximately 4.5 billion years. Chauvel stated that the results provide proof materials from the beginning of Earth's history exist in quantities large enough to be sampled.

Israel noted the work shows experimentally how the mantle crystallized from the magma ocean and created chemical heterogeneity from the start.

Tim Johnson of Curtin University, Bernard Bourdon of CNRS Lyon, and Richard Carlson of Carnegie Science described the measurements as a major technical achievement. A 2019 survey produced submarine relief maps confirming the volcano's location and shape. The research team concluded that Earth's mantle may contain more unmixed primordial material than previously thought.