An international team of scientists has revealed that below the Andes in South America, the Earth’s crust is collapsing toward the mantle over millions of years, according to a study recently published in the journal Science.Communications Earth & Environment .
This phenomenon is known as “lithosphere dripping”, a name derived from the fragmentation of the rocky materials that make up the Earth’s crust and upper mantle. The continuation of this long geological process for millions of years has led to the emergence of large deformations on the surface such as basins, crustal folds, and irregular elevations.
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A geological phenomenon in which a relatively cold, dense mass of lithosphere sinks into the more malleable upper mantle. around the world, including the Central Anatolian Plateau in Turkey and the Great Basin in the western United States, to name a few.
A research team led by geoscientists at the University of Toronto confirmed that several regions in the Central Andes in South America were formed in the same way..
“We confirmed that deformation on the surface of an area of the Andes led to the absorption of a large part of the lithosphere below,” said Julia Andersen, lead study author and a graduate student in geology at the University of Toronto in Canada.“.
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The “deformation” that Andersen refers to was found in the Arezzaro Basin and consists of wrinkles that were forming on the surface as the crust disappears below..
This occurs when the rocky crust warms and thickens, eventually starting to “drip” into the mantle.
“Given its high density, it drips like cold syrup or honey deep into the planet’s interior and may be responsible for two major tectonic events in the central Andes,” Andersen explained.
To reach this conclusion, the scientists recreated the process in the lab, using a tank and layered materials as backup units for the lower mantle, upper mantle, and crust..
“It was like creating and destroying mountain tectonic belts in a sandbox, floating in a simulated magma pool, all under incredibly accurate measurement conditions,” Andersen revealed.
The results of the model were then compared to geophysical and geological studies conducted in the central Andes, particularly in the Aresaro Basin, and the team found that changes in crustal elevation caused by drip in the lab “strongly follow changes in the height of the Aresaro River”.
“We also observed shortening of the folded crust in the model, as well as trough-like depressions on the surface, so we are confident that the droplets are very likely to be the cause of the observed deformations in the Andes,” Andersen added.
The experiments also showed other ways in which the distillation of the lithosphere can distort the Earth’s crust. Not all of this has been observed in the Andes, which suggests that there may be other regions of the world where different types of drip can be observed, if we can identify them..