Where in Earth’s crust is Carmen Sandiego? It turns out she’s in northern Canada, where geologists have finally used technology to spelunk to the “missing” tectonic plate—one they say disappeared beneath the crust about 60 million years ago.
Let’s dig into how tectonic plates live and die, and how Earth embodies those changes.
The rediscovered plate is called Resurrection, and while its probable demise beneath the magma waves happened 60 million years ago, it likely played a part in Earth’s surface for many millions of years before that. Tectonic plates float on the very outer surface of the Earth’s underlying structure, and they move around as a result of convection within Earth’s mantle. Plates can meet at neat seams, which is where volcanic systems like the Ring of Fire around the Pacific Ocean come into play.
But plates also collide, pretty violently by the geophysical-time standard, and this can result in dynamics like . . . well, a car crash. If a passenger vehicle slams into a tractor trailer, the passenger vehicle is almost always forced beneath the truck, right? Plates slide under and over the same way, and if the impact is strong enough, the plates can end up buckling or folding in half.
This is what researchers from the University of Houston think happened to the Resurrection plate. By using complex computer models to rewind time and rerun Earth’s tectonic history, they believe they’ve identified a remnant that was once the Resurrection plate. The secret is in a space previously believed to be part of another plate, fully blended today, but set apart by subtle clues the scientists uncovered.
“Our reconstructions show two coeval ridge-trench intersections that bound an additional ‘Resurrection’-like plate along the NW Cordillera prior to 40 Ma,” the scientists explain in the paper. “In this model, the Yukon slab represents a thermally eroded remnant of the Resurrection plate.” And if the Resurrection plate is real, that has a ripple effect for what other scientists believe about Earth’s tectonic history, too.
The best analogy could be, improbably, something like a croissant or even a sfogliatella. Imagine biting into a layered, flaky pastry and then using the innermost folds and layers to reverse engineer how the pastry began. This is what scientists are doing by using powerful beams that can see deep into Earth’s layers. The slightest evidence of subducted (sunken) and folded plates is used to backform the way those plates began at the surface.
Source: Popular Mechanics