Scientists Found a ‘Fingerprint’ in Ancient Rock That May Solve the Ring of Fire’s Origin

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Understanding the origins of the Ring of Fire, the most seismically active place on Earth, is famously difficult as geologic evidence is destroyed in the process.
Now a new study suggests that hundreds of millions of years ago, a process known as subduction “invasion” or “infection,” might’ve kickstarted the eastern Ring of Fire by causing subduction to cross a plate boundary and essentially spread to a neighboring plate.
Although evidence for this theory is based in the geologic record, the mechanism that causes this spread is still unknown.

Made up of some 450 volcanoes and stretching 25,000 miles, the Ring of Fire is the most seismically active region on Earth, but for geologists, it’s been difficult to discern exactly how this region formed. One idea is that the eastern ‘Ring of Fire’ initially formed through a process known as subduction “invasion” or “infection” where subduction—that is one tectonic plate sliding beneath another—sort of spreads like a contagion from one ocean plate to another.

This has been difficult to prove in the past, but a new study published in the journal Geology has created an invasion model for the paleo-pacific subduction that, University of Lisbon geologist João Duarte tells Scientific American, is “not just speculation” and instead relies on evidence from the geologic record. This could give us unprecedented insight on one of the most seismically dangerous areas of the world.

“A difficulty in recognizing ancient subduction invasion is that it may not leave a distinctive record,” the paper reads. “This paper proposes that Permian initiation of Paleo-Pacific Plate subduction along the East Asian margin was linked to the closure of ~east-west–trending oceans during the assembly of the Asian continent, including branches of the Paleo-Tethys Ocean and the Paleo-Asian Ocean.”

The very nature of understanding subduction origins is difficult, as the submerged crust is obliterated in the process, but this new study, led by Mark Allen from the University of Durham in the U.K., turns to an idea known as the “Dupal anomaly.” Initially discovered in 1984 when geologists noticed oceanic basalts with a specific chemical fingerprint associated with mid-ocean ridges and volcanoes.

The authors surprisingly found this long-lasting signature in volcanic rocks in the western Pacific, they surmised that material must’ve have spread from Tethys—an ocean that dominated the east some 300 million years ago when China was just a collection of islands—eastward, essentially crossing a plate boundary and “infecting” another plate and causing it to descend downward as well.

“It’s like seeing someone’s fingerprint at a crime scene,” Allen told Scientific American, “The dying act of those closing oceans may have been to infect the Pacific plate and start it subducting westward under the Asian continent.”

While this study provides evidence for subduction invasion, it doesn’t quite nail down the mechanism driving this geologic “contagion.” There’s also many other margins around the world that could play host to the next Ring of Fire, particularly the Atlantic plate which is relatively quiet. Earlier this year, Duarte published his own paper detailing how the Gibraltar Subduction Zone—where the African plate subducts beneath the Eurasian plate—is infecting the Atlantic.

Of course, these geologic processes don’t play out over human lifetimes, and instead, this Atlantic infection will take at least another 20 million years, according to Duarte and his team’s estimates.

When it comes to geology, it’s all about the long game.

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