Continents peeled from beneath drive ocean volcano formation

by Sophie Jenkins
London, UK (SPX) Nov 12, 2025
Earth scientists have determined that subcontinental material is gradually stripped from the underside of continents, moves into the oceanic mantle, and stimulates volcanic activity across ocean regions.

Researchers led by the University of Southampton found that ocean islands - including Christmas Island - exhibit high levels of certain enriched elements typical of continental geology. Prior theories had not explained how continental substances reached isolated areas deep within the ocean mantle.

Thomas Gernon, Professor of Earth Science at Southampton and lead author, stated, "We've known for decades that parts of the mantle beneath the oceans look strangely contaminated, as if pieces of ancient continents somehow ended up in there. But we haven't been able to adequately explain how all that continental material got there."

The team's simulations showed that as tectonic forces stretch continents, a mantle wave disrupts their roots at depths between 150 and 200 km. This slow process pulls fragments hundreds to thousands of kilometers into the oceanic mantle over tens of millions of years, where they feed volcanic eruptions.

Sascha Brune, co-author at GFZ in Potsdam, noted, "We found that the mantle is still feeling the effects of continental breakup long after the continents themselves have separated. The system doesn't switch off when a new ocean basin forms - the mantle keeps moving, reorganising, and transporting enriched material far from where it originated."

The team analyzed geochemical records from the Indian Ocean Seamount Province, tracking material flows triggered after Gondwana's breakup over 100 million years ago. Simulations and chemical studies revealed bursts of enriched magma soon after continental separation, fading gradually as continental inputs declined. This did not require mantle plumes or recycling of oceanic sediments.

Professor Gernon explained, "We're not ruling out mantle plumes, but this discovery points to a completely new mechanism that also shapes the composition of the Earth's mantle. Mantle waves can carry blobs of continental material far into the oceanic mantle, leaving behind a chemical signature that endures long after the continents have broken apart."

Recent related research by the group also found that mantle waves help trigger diamond eruptions and alter landscapes thousands of kilometers from tectonic boundaries.

Research Report:Enriched mantle generated through persistent convective erosion of continental roots