Plate Tectonics Weaken as They Sink; Research Reveals Pieces of Crust of Earth Bend Upon Entry in the Mantle

Findings of a recently published research led by ETH Zürich reconciled two hypotheses by showing plate tectonics are only substantially weakened as they sink.

The study concluded that these plates bend, a Mail Online report specified, as they sink into the Earth's mantle at so-called subduction zones, becoming segmented similar to a slinky snake.

More so, for the largest part, the motion of the plates of Earth is drawn by the cold, dense ocean crust's weight, sinking into the mantle, pulling the rest of the plate behind it.

Reasonably, subducting slabs need to stay intact as they slope into the mantle, else they would not be able to keep dragging along the attached crust. Nevertheless, geophysical evidence has introduced that these said tectonic plates were destroyed instead.

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(Photo: USGS/USGov, modified by Eurico Zimbres on Wikimedia Commons)
Tectonic plate boundaries

Plate-Weakening Methods Incorporated

In their research published in Nature, the study authors came to such a conclusion after they carried out computer simulations that explored the effect of all the different geological forces that impact subducting oceanic crust.

To date, the study investigators said, geophysicists have lacked an all-inclusive explanation for how the tectonic plates of Earth are bending minus breaking.

In their research, Taras Gerya, an ETH Zürich geophysicist, together with his colleagues, developed a 2D prototype of plate tectonics that incorporated different plate-weakening methods, which include data on how rock grains are changed in the deep mantle.

The model showed that upon the plates' entry into the mantle, it is abruptly bent downwards, leading its cold, brittle back to crack as the fine-scale grain construction along its underbelly changed, being left weakened.

Together, these are causing the plate the pinch at its weak points, leaving it whole but segmented, as mentioned, much akin to "slinky snake.

Simulations with Hotter Mantle

In this manner, the sloping slab can continue to grab the rest of the plate amidst turning distorted and folded. According to paper author Thorsten Becker, while this research has far from closed the book on what occurs in tectonic plates when they subduct into the mantle, it is not proving a convincing explanation of numerous essential geological processes.

Becker, a geophysicist at the University of Texas at Austin, added this stud is an example of the power of computational geosciences.

In their work, a similar Big World Tale report specified, the researchers combined the said two processes that geology and rock mechanics tell are taking place. They found that the general physics of how the Earth is working wouldn't have been expected. As a physicist, the study author elaborated, he finds it exciting.

The researchers experimented as well, running their simulations with a hotter mantle, resembling the conditions that would have been observed in the early Earth.

Snake-Like Tectonic

Under these conditions, the snake-like tectonic segments only got ahead of it, making it a couple of miles into the mantle before it broke off, suggesting that subduction may have just taken place sporadically.

The research team explained, their finding increases the probability that modern plate tectonics only started within the last billion years.

Professor Becker warned though that he thinks there are a lot of interesting debates for plate tectonics "being much older.

However, he added, the mechanism revealed by their model suggested things might be more sensitive to the mantle's temperature than it has ever been thought.

Related report about plate tectonics is shown on Evans Woolfe Media's YouTube video below:

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