Scientists have discovered the feathers of ancient “ghosts” that lurk under Oman.
Magma plumes are trapped in the thick section of the Earth’s crust and above the mantle, below the planet’s middle layer. As a result, the material cannot rise, causing volcanic activity on the surface. Researchers don’t know if the plume ever caused an eruption, but new research suggests that the trajectory of Indian tectonic plates shifted when it collided with millions of years ago.
The plume is located below the Salma Plateau in Oman (spelled as Salma and Selma), which can be up to 6,600 feet (2,000 meters). Pramates are likely to be formed for plumes, but some scientists have linked the formation of plateaus to the bending of the Earth’s crust created by the Macran subduction zone off the coast of Pakistan and Iran, Pilia told Live Science.
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“The plume is a hot material that you want to rise, rise, rise, so it’s so underneath, pushed up and creating terrain,” Pilia said. “Rise [at the Salma Plateau] It’s quite small, but it’s still there. Plume says it’s active. ”
Researchers have discovered seismic waves, or plumes, that travel across the earth at different speeds depending on the chemical composition of the material. In Oman, there is a dense network of stations recording seismic data, which enabled research, Pilia said. He named Ploom “Tick” after his son.
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Mite plumes are the first clear example of an amamatic “ghost” plume. This is the term for the research authors who studied to describe mantle plumes that do not cause volcanic activity. The mantle plume arises from the core mantle boundary, approximately 1,800 miles (2,900 kilometers) below the surface of the earth. These plumes usually burn volcanic eruptions with fuel. This is because it undergoes a process called decompression melting as it rises through the mantle and the crust.
Many mantle plumes cause volcanic eruptions in the middle of the oceanic plate, including Hawaii, Pilia said. However, the mantle rarely causes eruptions within the continental plate. The continent plates thicker crust and upper mantle than the ocean plate, so it cannot be raised or subjected to decompression melting.
Researchers generally assume that the lack of volcanic activity from the mantle plume on the continental plate means that there is no mantle plume below the continental plate, Pilia said. But “the lack of evidence is not evidence of absence,” he said. “If there’s no surface volcano, that doesn’t mean you don’t have a plume.”
Mite plumes are evidence that mantle plumes can exist without volcanic activity. “What we strongly believe in is that there are many other ghost plumes that we don’t know,” Pilia said.
Africa is a good candidate for the Ghost Plum. Because it is on one of the two great low speed states of the Earth. It is a continent-sized mass that protrudes from the boundary of the core mantle and feeds. Like Oman, Africa has areas with very thick crust and upper mantle, so plumes prevent them from rising to the surface, Pilia said.
“What we strongly believe in is that there are many other ghost plumes that we don’t know about.”
Salma Plateau is about 40 million years old. So Dani Plume is at least old, and was published online on June 6th in the journal Earth and Planetary Science Letters. The timing coincided with the collision between the Indian plate and the Eurasian plate, which prompted researchers to think about, Pilia said.
The collision occurred relatively close to current Oman before the two plates moved north to their current location. Pilia and his colleagues reconstructed the trajectory of the Indian plate and discovered a slight change in direction between 40 million and 25 million years ago.
“We did other calculations and demonstrated that essentially the shear stress generated by the plume is the reason for the change in azimuth. [angle] of the Indian plate,” explained Pilia.
Researchers already knew that plumes could redirect tectonic plates, but up until now, without knowledge of mites, they would not have linked this shift in trajectory to a particular plume.
The tectonic plates move, but the plume tends to stay there, Pilia said. This means that scientists can trace the evolution of the plume through evidence left in structural plates as they move over the plume.
However, in the case of Mite Plumme, this evidence was engulfed and erased by Macran’s subduction zone, Pilia said. “The evidence is forever gone.”
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