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Andes grew to huge heights in two explosive growth spurts



  Andes grew into two explosive & # 39; Growth storms & # 39; to enormous heights

The Cuernos del Paine in Chile are part of the Andes.

Credit: Shutterstock

Far from a smooth, inevitable rise, the emergence of the iconic Andean mountains was downright explosive. When the peaks rose tens of millions of years ago on the west coast of South America, the continent was shaken by violent volcanic eruptions, according to a new study.

The discovery was made by researchers, who examined the buried remains of the tectonic plates of the continent. And what the scientists found surprised her.

The 7,000-kilometer-long Andes ̵

1; the world's longest contiguous mountain range – did not develop as scientists had long thought. Previously, geologists had argued that the Nazca plate located beneath the eastern Pacific, South America, had been steadily and continuously sinking (sinking), raising the ground and eventually creating the towering Andes. [Photos: The World’s Tallest Mountains]

"The formation of the Andean mountains has long been a paradigm of plate tectonics," said Jonny Wu, co-author of the Assistant Professor of Geology at the University of Houston, in a statement.

Underground remnants of the Nazca plate, which lies about 900 kilometers underground, the researchers learned that the plate did not undergo continuous and continuous subduction. Rather, the Nazca plate was temporarily demolished from the Andes border (the place where it subducted), which led to volcanic activity, the researchers said.

To re-examine their work, scientists modeled volcanic activity along this margin.

"We were able to test this model by looking at the pattern of over 14,000 volcanic records along the Andes," some of which date back to the Cretaceous, Wu said.

The remains of the submerged Nazca plate are far underground, so how did the scientists study them?

When tectonic plates move underground, ie when they crawl under the earth's crust and invade the mantle, they sink like fallen leaves to the core, sinking to the bottom of a lake. However, these sink plates retain part of their shape and provide clues as to what the surface of the earth looked like millions of years ago. In the case of the Nazca plate, more than 5,500 km of lithosphere, the outer, rigid portion of the crust and the upper mantle, were lost to the mantle, the researchers said.

Scientists Can Depict These Plates Using Imaging Techniques Data collected from seismic waves allows physicians to see the inside of a patient, much like a computer tomograph (CT).

"We have tried to be more accurate than ever before, which has led to more detail than previously thought," said Wu. "We have managed to return to the age of dinosaurs."

In the case of this study, the researchers were able to compose the shape of the Andes after analysis of these underground tectonic remains. The disrupting Nazca plates collided with a transitional zone or a discontinuous layer in the mantle, which slowed the movement of the plate and caused it to build up, said the researchers.

Their model suggests that the flow of Nazca subduction In today's Peru, in the late Cretaceous, began about 80 million years ago, researchers wrote in the study. Then the subduction moved south, reaching the early Kenozoic in the southern Andes in Chile some 55 million years ago.

"Contrary to the current paradigm, however, Nazca subduction has not been fully continuous since the Mesozoic era, instead episodically involving different phases," the researchers write in the study.

The study was published online today (January 23) in the journal Nature.

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