Scientists discovered an ancient “ghost” panache that hides under Oman.
Magma’s plume is trapped under a thick part of the earth’s crust and the upper part of the mantle, the central layer of the planet. Consequently, the material cannot increase to trigger volcanic activity on the surface. Researchers do not know if the plume has never triggered eruptions, but the evidence suggests that it has moved the trajectory of the Indian tectonic plate during its collision with dozens of Eurasia millions of years ago, according to a new study.
The panache is located under the Salma d’Oman plateau (also spelled Salmah and Selma), which represents up to 6,600 feet (2,000 meters) high, the said main author of the study Simone PiliaGeophysicist and assistant professor at the King Fahd oil and mineral university in Saudi Arabia. The plateau has probably formed because of the plume, although some scientists link The formation of the plateau in the bending of the earth’s crust created by the makran subduction area off the coast of Pakistan and Iran, Pilia at Live Science told.
“A plume is a warm material that wants to get up, get up, get up – so it is below and grow up, creating a topography,” said Pilia. “The uprising (on the Salma plateau) is rather small, but it is still there. It tells you that the plume is active.”
The researchers discovered the plume thanks to the seismic waves or the sound waves which travel through the earth at different speeds depending on the chemical composition of the material. Oman has a dense network of stations that record seismic data, which has made research possible, said Pilia. He named the panache “Dani” after his son.
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The Dani panache is the first clear example of a “ghost” amagmatic plume – a term that the authors of the study invented to describe the plumes of the coat which do not trigger volcanic activity. The plumes of the mantle come from the border of the core of the mantle at around 1,800 miles (2,900 kilometers) below the surface of the earth. These plumes generally feed volcanic eruptions because they undergo a process called melting decompression as they go up through the coat and the crust.
Many mantle plumes trigger volcanic eruptions in the middle of the ocean plates, including in Hawaii, said Pilia. But the mantle plumes rarely trigger eruptions in continental plates; They cannot get up or undergo a fusion of decompression because they are a thicker crust and a higher coat than ocean plates.
Researchers generally assumed that the lack of volcanism of the plumes of the mantle in continental plates means that there are no mantle plumes under the continental plates, said Pilia. But “the absence of evidence is not proof of absence,” he said. “If you don’t have surface volcanism, that doesn’t mean you don’t have a plume.”
The panache Dani is proof that the plumes of the mantle can exist without volcanic activity. “What we firmly believe is that there are many other ghost plumes that we do not know,” said Pilia.
Africa is a good candidate for ghost plumes because it is above one of the earth Large Low Shear Provinces – Continent size stains that exceed the nucleus border and feed the plumes. Like Oman, Africa has regions with a very thick crust and a higher coat, so all the plumes would be prevented from climbing on the surface, said Pilia.
“What we firmly believe is that there are many other ghost plumes that we don’t know.”
The Salma plateau is around 40 million years old, which means that the panache Dani is at least as old, according to the study, which was published online on June 6 in the journal Earth and planetary science letters. This timing coincides with the collision between the Indian and Eurasian plates – and that made researchers think, said Pilia.
The collision occurred relatively close to what is now Oman, before the two plates move north towards their current positions. Pilia and her colleagues rebuilt the trajectory of the Indian plate and found that he had slightly changed management between 40 million and 25 million years.
“We have made a few other calculations and have essentially demonstrated that the shear stress produced by the panache was the reason for the change of azimut (angle) of the Indian plate,” said Pilia.
The researchers already knew that the plumes can redirect tectonic plates – but so far, without knowledge of Dani’s plume, they had not linked this change of trajectory to a specific plume.
Tectonic plates Move, but plumes tend to stay in place, said Pilia. This means that scientists can sometimes trace the evolution of a plume by evidence left on the tectonic plates when they move on the plume.
However, in the case of the Dani panache, these evidence was swallowed and erased by the Makran subduction zone, said Pilia. “These proofs have disappeared forever.”