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This is now the prevailing theory, but it was not until plate tectonics was accepted that it explains how much of the Earth’s crust slowly slides, grinds, rises, and sinks on top of its slimy mantle. The road was long and difficult.
But more than half a century after it was given scientific approval, the theory still needs some refinement.
A new study examining four plateaus in the western Pacific suggests that these vast regions are not solid slabs, but weak sections torn apart by distant forces at the edges of plates.
“The theory is not completely set in stone, and we are still discovering new things,” said co-author of the study, geophysicist Russell Pieskrywek of the University of Toronto.
“I knew that geological deformations such as faults occur inside continental plates, far from plate boundaries. But I didn’t know that the same thing was happening on oceanic plates.” added lead author Erkan Gün, a geoscientist at the University of Toronto. .
For decades, scientists have been rewriting our understanding of the ocean floor. So this new study is just a continuation of their efforts to map the ocean’s rugged topography.
In the 1950s, the pioneering work of marine cartographer Marie Tharp, who used sonar data from warships to map much of the ocean floor, revealed that ocean basins do not have the completely flat surface that scientists had suspected. It was shown that there is no.
Rather, the ocean floor has been carved out by gaping trenches and gigantic mountains, no larger than the mid-Atlantic ridge discovered by Tharp, now recognized as the longest mountain range on Earth that cuts the Atlantic Ocean in two. has been done.
These mountains form when two plates collide, bending the Earth’s crust, or when one plate subducts beneath the other, pushing the plate it overcomes upward. Underwater, however, two plates typically flow apart at so-called diverging boundaries, and magma erupts, forming underwater mountain ranges.
But far from these plate boundaries, in the centers of oceanic plates, much of the Earth’s crust remains fairly rigid while floating above the mantle and does not deform as it does at the edges of the plates, science says. the people thought.
To test this idea, Gün, Piskliwek and colleagues collected existing data on two oceanic plateaus between Japan and Hawaii called the Schatzky and Hess uplifts. Ontong Java Plateau in the northern Solomon Islands. and the Manihiki Plateau, northeast of Fiji and Tonga.
Because of the challenges of seafloor exploration, the study was limited to these four plateaus in the western Pacific Ocean where data were available.
Oceanic plateaus are located hundreds to thousands of kilometers from the nearest plate boundary. However, Gün et al. found that these plateaus share deformed and magmatic characteristics. This suggests that the plateau is being torn apart by pulling forces at the edge of the Pacific plate, where the slab is subducting beneath an adjacent plate.
The faults, or fault lines, identified by the researchers tend to run parallel to the nearest ocean trench, as you can see in the map above.
The researchers also investigated the plate tectonic dynamics of four hypothetical plateaus located between 750 and 1,500 kilometers (466 and 932 miles) from the nearest subduction zone to better understand the mechanisms driving this distant deformation. Modeled.
Regardless of their distance from the edge of the plate, these hypothetical plateaus stretched over millions of years and became even thinner on the side closest to the trench.
“It was thought that because the oceanic plateau is thicker, it should be stronger,” Gün says. “But our models and seismic data show that the opposite is actually true: the plateau is weaker.”
The researchers acknowledge that they have only analyzed four of the Pacific plateaus, and hope their findings will spur further exploration to map the ocean floor.
“Sending out research vessels to collect data is a huge effort,” Gün said. “So we’re actually hoping that our paper will gain traction during the plateau and that more data will be collected.”
This research Geophysical Research Letters.
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