An international team of scientists has discovered that under the Andes mountain range in South America, the earth’s crust is eroding into the mantle over millions of years.
According to a study recently published in the journal Communications Earth & Environment, this phenomenon is known as “lithospheric dripping,” a name derived from the fragmentation of the rocky material that makes up the earth’s crust and upper mantle.
This long geological process, which lasted millions of years, led to the emergence of large surface deformations, such as depressions, folding of the earth’s crust and uneven elevations.
This is a geological phenomenon in which a relatively cold and dense mass of the lithosphere sinks into a more pliable upper mantle.
While this process is a relatively new concept in the field of plate tectonics, having been around for decades, many examples of “lithospheric flow” have been identified around the world, including the Central Anatolian Plateau in Turkey and the Great Basin in the western United States, to name but a few.
Now a research team led by geologists from the University of Toronto has confirmed that several regions in the Central Andes of South America formed in the same way.
“We have confirmed that surface deformation in the Andean region has engulfed much of the lithosphere below,” said Julia Andersen, lead author of the study and PhD student in the Department of Geology at the University of Toronto, Canada. .
The “deformation” Andersen refers to was found in the Aresarro Basin and consists of folds that formed on the surface as the crust disappeared below.
This happens when rocky crust heats up and thickens, eventually dripping into the mantle.
Andersen explained: “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: changing the topography of the region’s surface by hundreds of kilometers and crushing and stretching the surface crust itself.” .
To reach this conclusion, the scientists recreated the process in the lab, using the reservoir and layered materials as backup units for the lower mantle, upper mantle, and crust.
“It was like creating and breaking mountain tectonic belts in a sandbox, swimming in a simulated magma pool, all under incredibly precise measurement conditions,” Andersen said.
The results of the model were then compared with geophysical and geological surveys conducted in the central Andes, especially in the Aresaro Basin, and the team found that changes in crustal height caused by drip irrigation in the lab “strongly follow changes in Aresaro height.” River”.
“We also observed shortening of the folded crust in the model, as well as troughs on the surface, so we are confident that drops are most likely the cause of the deformations seen 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 these have been observed in the Andes, which suggests that there may be other regions of the world where different types of drops can be observed, if we can identify them.
In turn, this also suggests that non-subduction processes may play a more important role than we think in shaping our planet’s surface.
Currently, only lithospheric distillation has been identified on Earth, but scientists are confident that it can be detected in the future through modeling and experiments on other planets without plate tectonics, such as Mars and Venus.
Source: Science Alert.