Structures near Earth’s core may be the result of interplanetary collision

(ORDO NEWS) — A 4.5 billion-year-old collision of Earth with a planet the size of Mars could have irreversible impacts on our planet’s deep mantle, according to a study recently published in the journal Nature Geoscience. Scientists speculate that a group of mysterious super dense structures near the Earth’s core may be the remnants of an ancient interplanetary collision.

These strange structures are known as ultra-low velocity zones (ULVZs) because the seismic waves generated by earthquakes travel through them about 50% slower than through the surrounding mantle. This means that the ULVZ is also much denser than the rest of the mantle, and is possibly composed of heavier elements.

It is difficult to say anything for certain about these dense clumps of rock because the ULVZ are about 2,900 km below the surface of the Earth. Only seismic data can provide some indication of the size, shape and structure of these zones.

Recently, using a new computer model and fresh seismic observations deep beneath Australia and New Zealand, researchers may have added an important piece to the ULVZ puzzle. These zones are not homogeneous structures, but rather are composed of layers of different materials that have accumulated over millennia, according to new research.

After computer simulations showed that a layered or mixed structure likely existed within the ULVZ, the researchers proposed a possible history of the origin of these structures – a history that began more than 4 billion years ago, around the time when the stony crust first formed in the early The earth. Below the surface, heavier elements, such as iron, sank towards the planet’s core, while lighter elements, such as silicon, rose to the mantle.

This entire organization was disrupted when a Mars-sized planet known as Theia crashed right into early Earth – an ancient cataclysm that researchers call the giant impact hypothesis. According to scientists, the collision could throw a huge amount of debris in the Earth’s orbit, which could lead to the formation of the moon, as well as raise the temperature of the entire planet and create a large “ocean” of magma on the planet’s surface.

The researchers said that various rocks, gases and crystals formed during the collision would have been scattered across this ocean of magma, but not forever. Over the next billion years, heavier materials would sink to the bottom of the mantle, and then lighter ones, which ultimately led to the creation of a densely layered structure of iron and other elements at the core-mantle interface. As the mantle churned over the centuries, this dense layer would have split into smaller clumps scattered across the lower mantle, effectively giving us the now known ULVZs.

However, the researchers added that this scenario may not explain the origin of all ULVZs, as there is also some evidence that other phenomena, such as melting of the oceanic crust sinking into the mantle, may also be responsible for the formation of ULVZs. However, the team’s models show that the giant impact hypothesis reliably explains how dense, multi-layered zones could have been created.


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