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Geologists have discovered the Earth's lacking tectonic plate

Northern Canada has kept a secret from the rest of the world. It is home to "Resurrection", a tectonic plate that has been theorized a lot but has never been found until now. A team of researchers used a CAT scan of northern Canada and the mantle underneath to find the missing plate.

The discovery could lead to a better prediction of hazards and also to the discovery of mineral and hydrocarbon deposits. But better than that, it helps scientists piece the earth's history together.

A missing tectonic plate is like a missing piece of the puzzle. Without it, our understanding of the bigger picture is impaired. Some scientists say it didn't exist at all, while others say it was pulled into the Earth's mantle 40 to 60 million years ago. But now it seems to have been found.

"We believe we have direct evidence that the Resurrection Plate existed."

Spencer Fuston, PhD student in geology, University of Houston.

The paper in which this new result is presented is entitled “Resurrection of the Resurrection Plate from a tectonic reconstruction of an unfolded plate in northwest North America since the early Cenozoic”. The authors are Spencer Fuston and Jonny Wu from the College of Science and Mathematics at the University of Houston. The paper was published in the Bulletin of the Geological Society of America.

"Volcanoes form on plate boundaries, and the more plates you have, the more volcanoes you have," said co-author Jonny Wu, assistant professor of geology in the Department of Earth and Atmospheric Sciences. "Volcanoes also affect climate change," Wu said in a press release. "So if you're trying to model the earth and understand how the climate has changed since time, you really want to know how many volcanoes there have been on earth."

Putting the history of the earth together is a major challenge. Volcanic activity is strongly linked to historical climate change and also to mass extinction. Earth's worst mass extinction, the Permian Triassic Extinction or the Great Extinction, was triggered by massive, sustained eruptions in Siberia about 252 million years ago. A missing tectonic plate could be a missing clue in the mystery of the earth's geological past.

The University of Houston Tectonics and Tomography Center developed a type of imaging called plate unfolding. There are many types of tomography, but they all represent things in sections. Co-author Wu is part of an effort to develop a way to acquire and unfold 3D seismic tomography images. The method restricts plate tectonic reconstructions. Wu and a separate team of researchers used the method to reconstruct plate tectonics of the Philippine Sea and East Asia since 52 mya.

When a panel is pulled back towards the mantle, it becomes a folded panel. Tomography can image these folded structures, and the plate unfolding technique can pull the plate out, then unfold it, and stretch it back to its original shape.

A 3-D block diagram across North America showing a mantle tomography image shows the plate unfolding method used to flatten the Farallon tectonic plate. In this way, Fuston and Wu were able to locate the lost resurrection plate. Photo credit: Wu and Fuston, 2020.

Now, Wu and colleague Fuston, a third-year graduate student in geology, have used plate unfolding to reconstruct the tectonic plates in the Pacific during the early Cenozoic era. Geologists know that there were at least two plates in the Pacific, Kula and Farallon. A third plaque called Resurrection has been proposed to explain a specific type of volcanic belt along Alaska and Washington State. So far there has been only weak evidence.

“We believe we have direct evidence that the Resurrection Plate existed. We're also trying to resolve a debate and stand up for our data backing side, ”said Fuston.

"If the boundaries of this ancient tectonic plate of the resurrection are raised back to the surface and reconstructed, they will fit well with the ancient volcanic belts in Washington State and Alaska and provide a coveted link between the ancient Pacific and the North American geological record," explained Wu.

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