Although this is now the prevailing theory, the road to acceptance has been long and bumpy Tectonic platesWhich describes how large portions of the Earth's crust slide, grind, rise and sink very slowly through its sludge cloak.
But so far, More than half a century Now that it has received scientific approval, the theory needs some improvement.
A new study looking at four plateaus in the western Pacific Ocean suggests that these extended regions are not solid plates, but rather weak spots being yanked away by forces far away at the plate edge.
“The theory is not etched in stone and we are still discovering new things.” He says Russell Biskelewic, a geophysicist at the University of Toronto, who co-authored the study.
“We knew that geological deformations such as faults occur in the interior of continental plates far from plate boundaries. But we did not know that the same thing was happening to ocean plates.” Add First author Erkan Gün, also an earth scientist at the University of Toronto.
For decades, scientists have been rewriting their understanding of the seafloor, so this new study is just a continuation of their efforts to map the ocean's rugged terrain.
In the 1950s, the pioneering work of ocean cartographer Mary Tharp was… Mapping large parts of the sea floor The use of sonar data from warships showed that ocean basins did not have flat surfaces at all as scientists had suspected.
Instead, the seafloor was carved by vast trenches and huge mountains – none larger than the Mid-Atlantic Ridge, which Tharp discovered, and which is now known as the Mid-Atlantic Ridge. The longest mountain range on the planetcutting the Atlantic Ocean into two parts.
This is amazing Mountain ranges are formed When two tectonic plates collide and the Earth's crust buckles, or one plate subsides beneath the other, pushing the upper plate upward. Underwater, however, submarine mountains typically form when two plates drift apart at so-called divergent boundaries and magma is released.
But away from the plate boundaries, at the center of the oceanic plates, scientists thought that large parts of the Earth's crust remained fairly rigid as they drifted over the mantle, and did not deform like plate edges.
To test this thinking, Gunn, Biskelewic and their colleagues collected data on two oceanic plateaus located between Japan and Hawaii, called the Shatzki Ridge and the Hesse Ridge; Ontong Java Plateau, northern Solomon Islands; The Manihiki Plateau, to the northeast of Fiji and Tonga.
Given the challenges of seafloor surveying, their study was limited to the four plateaus in the western Pacific Ocean for which data were available.
Oceanic plateaus are located hundreds to thousands of kilometers from the nearest plate boundaries. However, Gunn and his colleagues found that the plateaus share deformational and magmatic features, suggesting that they were torn apart by gravitational forces at the edge of the Pacific Plate, where plates are subducted beneath neighboring plates.
The fissures, or fault lines, identified by researchers tend to run parallel to the nearest trench, as you can see on the map above.
The team also modeled the plate tectonic dynamics of four hypothetical plateaus located between 750 and 1,500 kilometers (466 to 932 miles) from the nearest subduction zone, to gain a better understanding of the mechanisms driving this distant deformation.
Regardless of their distance from the plate edge, these hypothetical plateaus have extended over millions of years and become thinner on the side closer to the trench.
“It was thought that because the plateaus under the ocean are thicker, they must be stronger,” says Gunn He says. “But our seismic models and data show that it is actually the opposite: the plateaus are weaker.”
While acknowledging that they only analyzed four plateaus in the Pacific Ocean, the researchers hope their findings will stimulate further exploration to map the seafloor.
“Sending out research ships to collect data is a huge effort,” Gunn says He says. “So, actually, we hope that our research will draw some attention to plateaus and that more data will be collected.”
The study was published in Geophysical Research Letters.
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