Why the collision of two tectonic plates can split the Earth in two – Diario La Página

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Our planet is in constant movement. But not only around the Sun or even on its own axis. It is a planet alive from its core, with the daily movements of its tectonic plates dozens of kilometers beneath its surface.

In a presentation at the American Geophysical Union conference in San Francisco last December, researchers from institutions in the United States and China revealed they had discovered that Tibet may be splitting in two beneath the rising Himalayas, with pieces of the continental plate breaking away. . The scientists recently published a version of their research that has not yet been peer-reviewed.

Research shows that the geology beneath the world’s highest mountain range may be even more complex than previously believed. The Himalayas grow because two continental tectonic plates, the Indian and the Eurasian, collide under this colossal mountain range.

Tectonic plates are like the pieces of a puzzle that make up the Earth’s crust. They move over the Earth’s mantle, which due to the pressures it resists, can be found as a “viscous paste” or in a solid state.

In cases where oceanic and continental plates collide, the denser oceanic plate slides beneath the lighter continental plate in a process called subduction. However, when two equally dense continental plates collide (as is the case beneath the Himalayas), it’s not as simple to predict which plate will end up beneath the other, and geoscientists still aren’t sure what exactly is happening in Tibet.

The Himalayas are a geographical wonder that has been in development for 52 million years and has in its mountain range Mount Everest, the highest peak in the world, at 8,848 meters. In the mid-Eocene, the Indian Plate (which was then an island) collided with the Eurasian Plate and eventually formed the world’s tallest mountains.

For decades, some scientists have argued that the Indian Plate has resisted deep submergence into the mantle (also known as subduction) and is instead moving horizontally beneath the Eurasian Plate, the other tectonic plate that makes this mountainous masterpiece possible. However, an opposing faction insists that the Indian Plate is actually subducting beneath the Eurasian Plate and melting into magma.

But an international team of geodynamics professionals decided to follow a third path, borrowing wise words from a famous meme: “Why not both? Their new study argues that the Indian plate beneath the Tibet region is undergoing a process known as delamination, where the top of the plate rubs against the Eurasian plate while the bottom part splits and subducts into the mantle.

Understanding the dynamics at play 100 to 200 kilometers beneath these mountains can help scientists complete a more accurate picture of how the Himalayas have formed, while also understanding potential seismic threats to the region. The researchers originally presented their findings in December 2023 at the American Geophysical Union conference and have now published a non-peer-reviewed preprint in the scientific journal ESS Open Archive.

While this tectonic opening has been theorized and even recreated using computer models, this is the first time scientists have captured a plate in the act of delaminating. “We didn’t know that continents could behave this way and that, for solid earth science, is quite fundamental,” said Dr. Douwe van Hinsbergen, a geodynamicist at Utrecht University.

Despite the potential concern, studies of mantle and crustal density suggest that the fairly buoyant Indian continental plate should not sink so easily, meaning that submerged sections of the crust must still be grinding under the belly of the Eurasian plate instead of being sunk deep into the mantle.

Another possibility is that the Indian plate is distorting in a way that causes some parts to wrinkle and bend, and others to sag and sag.

Stanford geophysicist Simon Klemperer became interested in an area near Bhutan in northeastern India: the subduction zone curves there due to the non-uniform composition of the Indian plates. Klemperer took a series of measurements of helium isotopes (specifically, helium-3) surfacing in nearby springs.

After collecting samples from about 200 springs over about 900 kilometers, they found a marked line where mantle rocks (subduction) meet crustal rocks (non-subduction). However, a trio of springs south of this line contained mantle signatures; In other words, the Indian Plate was probably splitting in two.

Additionally, earthquake analysis from hundreds of seismic stations also appeared to highlight two “spots” that likely point to a lower slab separating from a higher slab.

Although this drama has been unfolding for millions of years, scientists are only beginning to uncover the complex dynamics of what forms land masses around the world.

Understanding how and why plates sometimes experience this “why not both” behavior will help better predict earthquake hazards on both the “roof of the world” and the rest of the faults, anywhere where an unstoppable force apparently encountering an immovable object.