Continents peel from under, triggering oceanic volcanoes

Published:


2025-11-12 13:41:00

Earth scientists have found how continents are slowly peeled from beneath, fuelling volcanic exercise in an sudden place: the oceans.

The analysis, led by the University of Southampton, reveals how slivers of continents are slowly stripped from under and swept into the oceanic mantle – the new, largely stable layer beneath the ocean flooring that slowly flows. Here, the continental materials fuels volcanic exercise for tens of hundreds of thousands of years.

The discovery solves a long-standing geological thriller: why many ocean islands removed from plate tectonic boundaries comprise supplies that look distinctly continental, regardless of being discovered in the course of oceans.

The research, printed in

Nature Geoscience

, was led by the University of Southampton, and concerned the GFZ Helmholtz Centre for Geosciences in Potsdam, Germany, the University of Potsdam, Queen’s University Canada, and Swansea University.

Ancient chemical trails within the mantle

Many ocean islands, reminiscent of Christmas Island within the northeast Indian Ocean, comprise unusually excessive ranges of sure so-called ‘enriched’ components which are usually present in continents – presumably as a result of deep Earth processes have folded in older, recycled materials, very similar to a churning cake mixer.

It was thought these components got here from sediments that get recycled when ocean plates dive into the mantle, or by columns of scorching rock, often called mantle plumes, which rise from deep inside the Earth.

But these explanations fall quick, as some volcanic areas present little signal of crustal recycling, whereas others seem too cool and shallow to be pushed by mantle plumes.

“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,” mentioned Thomas Gernon, Professor of Earth Science on the University of Southampton, and lead creator of the research. “But we haven’t been able to adequately explain how all that continental material got there.”

The continents are peeling from under

The research proposes a novel reply: continents don’t simply rift aside on the floor – additionally they peel away from under, and over a lot better distances than beforehand thought potential.

The scientists developed simulations to imitate the behaviour of continents and mantle as they’re stretched by tectonic forces.

Their work builds on their earlier analysis displaying that when continents break aside, deep tectonic forces set off a wave of instabilities – a ‘mantle wave’ – that sweeps alongside the continents’ base, disturbing their roots at depths of 150 to 200 km.

This sweeping motion unfolds at an extremely gradual tempo, only a millionth the velocity of a snail, progressively stripping materials from the deep roots of continents.

These peeled fragments are then swept sideways – typically over greater than 1,000 km – into the oceanic mantle, the place they feed volcanic eruptions within the ocean over tens of hundreds of thousands of years.

Study co-author Professor Sascha Brune, of GFZ in Potsdam, mentioned: “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.”

Evidence from the Indian Ocean

The staff analysed geochemical knowledge from areas of the Earth together with the Indian Ocean Seamount Province, a series of volcanic options fashioned after the supercontinent Gondwana broke aside over 100 million years in the past.

Through simulations and chemical evaluation, they found that quickly after Gondwana broke aside, a burst of unusually enriched magma rose to the floor.

Over tens of hundreds of thousands of years, that chemical sign light because the circulate of fabric from beneath the continent waned. This occurred with out a mantle plume coming from deep within the Earth, which geologists had lengthy assumed have to be accountable.

Professor Gernon defined: “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.”

The research builds on the staff’s current discovery that mantle waves also can stir dramatic modifications deep inside continents. Their earlier work confirmed that these gradual, rolling actions within the Earth’s mantle can assist set off

diamond eruptions

and even

reshape landscapes

1000’s of kilometres from the sides of tectonic plates.