Scientists: North America is "draining" into the Earth's mantle

Under certain states, giant "drops" of rock are forming, hanging from the underside of the continental crust.

Scientists from the University of Texas at Austin have captured for the first time the process by which a part of the North American crust is literally "dripping" into the mantle. This phenomenon is associated with remnants of an ancient oceanic plate buried beneath the Midwest of the United States.

The research showed that beneath areas from Michigan to Nebraska and Alabama, giant "drops" of rock are forming, which hang from the underside of the continental crust and extend to depths of up to 640 km. These formations draw in rocks from a vast territory of the continent, causing a gradual loss of material in the lower part of the crust.

According to the study's author, Junling Hua, a professor at the University of Science and Technology of China, the reason lies in the ancient fragment of the Farallon oceanic plate. Millions of years ago, it subducted beneath the North American plate and partially remained at the boundary of the transition zone of the mantle and the lower mantle - at a depth of about 660 km. Its gravitational influence causes horizontal movement of rocks and their "suction" downward.

To confirm their hypothesis, scientists modeled the process using computer simulation. When the Farallon plate remnant was present in the model, the "drop" zone formed, and in its absence, it disappeared. This convincingly demonstrates that the plate fragment can influence a vast part of the continent.

Although this geological phenomenon will not lead to changes on the surface in the foreseeable future, it helps scientists better understand the processes occurring within the planet and explains how continents can form, break apart, and redistribute.