Hidden connection unites the largest volcanoes in the Pacific

Scientists have long puzzled over a curious geological mystery in the Pacific Ocean: could one deep-sea hotspot be responsible for both a sprawling underwater volcano chain and the largest volcanic plateau on Earth?

After years of uncertainty, a new study connects these distant features, revealing a much clearer picture of how the Pacific Ocean floor has shifted and evolved.

The research, led by geologists from the University of Maryland and the University of Hawaiʻi, points to the Louisville hotspot as the common source of both the Louisville Ridge – a chain of underwater volcanoes – and the vast Ontong Java Plateau.

Their findings, published in the journal Nature, are helping to rewrite the volcanic history of the Pacific Ocean.

Volcanoes share hidden origin

“Up until now, we’ve had this extremely disconnected picture of the Pacific and its volcanoes,” said Val Finlayson, the study’s lead author.

“But for the first time, we’re able to make a clear connection between the younger southern and older western Pacific volcanic systems. It’s a discovery that gives us a more complete history of how the Pacific Ocean basin has evolved over millions of years to become what it is today.”

The Ontong Java Plateau, located north of the Solomon Islands, is a massive submerged volcanic platform. It’s about 120 million years old and has puzzled researchers due to its size and unclear origins.

Meanwhile, the Louisville hotspot, located in the southern Pacific Ocean, has long been known to generate a line of underwater volcanoes. Scientists had suspected the two might be linked, but no one could prove it – until now.

Volcanic clues beneath the crust

Part of the difficulty in confirming the connection came from the disappearance of key evidence. Over time, portions of the Louisville hotspot track were pushed beneath the Earth’s crust through subduction, making direct study impossible.

“Much of the physical evidence for a connection between Louisville and Ontong Java has disappeared because part of the Louisville hotspot track was subducted, or pushed, under tectonic plates in the Pacific region,” Finlayson explained.

“We had to sample deeply submerged volcanoes from a different long-lived hotspot track to find evidence from tens of millions of years ago that suggested our models for the Pacific plate needed revision.”

Footprints of a hidden past

The breakthrough came when the team explored underwater mountains near Samoa. They expected to find relatively young volcanic structures. Instead, the researchers uncovered mountains far older than anticipated. Using rock samples, they analyzed both the age and chemical composition of the formations.

The data told a surprising story: the mountains were part of an ancient segment of the Louisville volcanic track. These volcanoes, formed by the same hotspot, left behind what the team likened to a trail of “footprints.”

“We can track these ‘footprints’ across time and space,” Finlayson said. “The footprints get progressively older as you move away from an active hot spot, similar to how your own footprints will fade away in the sand as you walk.”

“But you can still tell that these prints belong to the same source. Thanks to this new evidence, we were able to revise current models of Pacific plate motion and gain a better understanding of how the seafloor has moved over millions of years.”

Rewriting volcanic history

This improved understanding of Pacific plate movement doesn’t just fill in a missing chapter of geological history – it could help with future studies of volcanoes across the world.

Many Pacific islands are built on volcanic foundations, and a better grasp of how those formations developed could be useful for both researchers and local communities.

The research team now plans to apply these updated models to other mysterious volcanic features, both below the ocean surface and above it.

“We’ve solved one mystery, but there are countless more waiting to be unraveled. This finding offers us a more accurate history of the Pacific and its volcanic activity and helps us understand more about the dynamics and style of volcanism that occurs there,” Finlayson said.

“Everything new we learn about the Earth’s tumultuous past helps us better understand the dynamic planet we live on today.”

The full study was published in the journal Nature.

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