2023-11-02 09:30:00
Read in full version 02.11.2023 12:30, Gennady Detinich A common hypothesis states that at the dawn of the formation of the Solar system, the planet Theia, the size of Mars, crashed into the Earth. The impact led to the formation of the Moon from the remains of Theia, and traces of the remaining debris were never discovered. New modeling has shown that the remains of an ancient planet have sunk into our planet’s mantle and are still floating around in huge chunks. Image source: California Institute of Technology In the recent past, scientists have already carried out calculations that might suggest the origin of two giant anomalies at the junction of the Earth’s core and the lower layers of its mantle. Back in the 80s of the last century, geophysicists were surprised to find out that in the depths of our planet there are two giant continents, each several thousand kilometers long. This was indicated by seismic waves that moved differently in these mysterious areas than in the surrounding mantle. These “objects” were called large low-shear-velocity provinces (LLSVP) and hypotheses regarding their formation began to be developed. At the same time, the study of the Moon was underway; fortunately, by that time the Apollo missions had delivered samples from its surface to Earth. It turned out that the Moon and the Earth’s mantle rocks have the same origin and composition, which made us think regarding the impact appearance of the Moon. Calculations have shown that the Moon might have formed regarding 4.5 billion years ago when a planet the size of Mars fell to Earth. The search for other remains of this hypothetical planet, which was given the name Theia, was unsuccessful. They were not in near-Earth space and in the main asteroid belt. Scientists have suggested that the remains of Theia sank into the depths of the then molten Earth. New and more detailed modeling, led by scientists from Caltech, showed that the LLSVP regions are very likely to be the remnants of Theia. They retained their monolithic structure due to the fact that the lower mantle layer of the Earth was not hot enough for mixing to occur, and the remains had time to crystallize. Thanks to this, today we can see them in the process of seismic research. The appearance of such gigantic foreign inclusions in the bowels of the Earth obviously influenced all subsequent geological processes on our planet. Scientists have yet to assess this influence on the early evolution of the Earth.
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