The team used a method called slab unfolding, which allows them to work backwards from the remains of a subducted plate and work out what it looked like on the surface, millions of years agoUniversity of Houston
The face of the Earth has changed drastically over its life, with plates shifting and sinking. Now, geologists at the University of Houston claim to have found the remains of an ancient tectonic plate beneath Canada that was pushed under the surface tens of millions of years ago.
It’s long been known that in the early Cenozoic Era – around 60 million years ago – there were two major tectonic plates, called Kula and Farallon, in the Pacific Ocean off the western coast of North America. But debate has raged about whether they were joined by a third, oddly named Resurrection, which would have since sunk beneath the surface. And now, the geologists on the new study say they’ve found this missing plate.
Two of the objects they studied are already known – the Alaska and Cascadia slabs, which are still attached to each other. The Alaska slab sits beneath the Aleutian Islands and is thought to be the remains of the Kula plate, while the Cascadia slab lies under southern California and represents the remains of Farallon.
But intriguingly, the team identified a third slab detached from the others, about 400 to 600 km (250 to 370 miles) below the surface of northern Canada. They call it the Yukon Slab, and when the clock is wound back it appears to fit the calculated shape of the old Resurrection plate.
“When ‘raised’ back to the earth’s surface and reconstructed, the boundaries of this ancient Resurrection tectonic plate match well with the ancient volcanic belts in Washington State and Alaska, providing a much sought after link between the ancient Pacific Ocean and the North American geologic record,” says Jonny Wu, co-author of the study.
The team’s model suggests that the Yukon slab gradually made its way northeast after the Resurrection plate was first subducted some 40 million years ago.
https://youtu.be/trIMtS098PQ
https://newatlas.com/science/ancient-tectonic-plate-discovered-canada/
