Long-Lost Tectonic Plate Discovered Hundreds of Miles Below Canada

A team of scientists say they have uncovered evidence of a mysterious tectonic plate beneath northern Canada that some experts argue never existed.

In a study published in the Geological Society of America Bulletin, the researchers from the University of Houston identified the remains of the ancient plate—which had mostly disappeared by around 40 million years ago—hundreds of miles beneath Canada's Yukon territory.

Whether or not the plate—dubbed "Resurrection"—ever existed has long been a hot topic of debate in the field of geology.

Tectonic plates are vast slabs of the planet's crust, which are in constant, albeit very gradual, motion. Regions where these plates meet tend to be seismically and volcanically active.

Geologists have long known that there were two tectonic plates—called Kula and Farallon—at the beginning of the Cenozoic Era (66 million years ago to the present day) in the Pacific Ocean off the western coast of North America.

But some experts have suggested that a third plate, Resurrection, may have accompanied Kula and Farallon for a time before it mostly sunk beneath the Earth's surface between 60 and 40 million years ago, in a process known as "subduction."

As Resurrection slid under the North American Plate—which contains most of North America, as well as Greenland, the northern Caribbean, and parts of Siberia, Iceland, and the Azores—it would have melted and deformed due to the extreme heat of the Earth's interior, becoming significantly smaller in size.

Now, University of Houston researchers say they have found a large chunk of the crust they believe represents the remains of Resurrection.

Firstly, the scientists analyzed existing mantle topography images, which provided a snapshot of the Earth's interior beneath North America.

This analysis revealed a chunk of rock 250 to 370 miles below the Yukon, which they have dubbed the "Yukon Slab."

The team then used a computer modeling technique called "slab unfolding" in order to reconstruct what any subducted plates once looked like in the area. This approach revealed that the Yukon Slab closely matched the hypothesized shape of the Resurrection plate toward the beginning of the Cenozoic Era.

"We believe we have direct evidence that the Resurrection plate existed," Spencer Fuston, co-author of the study from the University of Houston, said in a statement. "We are also trying to solve a debate and advocate for which side our data supports."

The researchers say the latest findings could improve our ability to predict volcanic hazards in the region and identify mineral deposits, while also providing new insights into the Earth's climate.

"Volcanoes form at plate boundaries, and the more plates you have, the more volcanoes you have," Jonny Wu, another co-author of the study, said in a statement. "Volcanoes also affect climate change. So, when you are trying to model the earth and understand how climate has changed since time, you really want to know how many volcanoes there have been on earth."

North America tectonics
A plate tectonics reconstruction of western North America 60 million years ago, showing the Kula, Farallon and Resurrection plates. University of Houston