What if everything we know about plate tectonics was called into question? Until now, to understand what the internal zone of the Earth is made of, between the core and the lithosphere (the layer closest to us), geographers have had to use seismographs.
Thanks to the tremors, they were able to calculate the speed of propagation of the waves and determine the position of the tectonic plates. Subduction zones, which constitute the boundaries between two plates, have been commonly mapped by the scientific community.
However, the die seems to have been cast again, since geophysicists from the Zurich Polytechnic and the California Institute of Technology (Caltech) discovered anomalies in the lower mantle of the Earth, indicating unknown rocky areas , according to Phys.
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A particularly unexpected discovery
As part of their study published on November 4, 2024 in the journal Nature, the researchers used a new high-resolution model of the Earth’s mantle. Unlike geographers’ traditional approach, their research relied on an advanced geophysical imaging method called “full waveform inversion” (“Full Waveform” Inversion in English). A very powerful tool used to estimate the properties of underground materials by analyzing the propagation of seismic waves, particularly in the oil sector.
And this is how researchers put their finger on a surprising discovery: rocky areas submerged under the great oceans and inside continents whose boundaries do not correspond with those we know. One of these zones has notably been identified under the western Pacific, close to another already known, which until now seemed impossible.
A turning point in terrestrial exploration
The researchers, disconcerted, did not expect such discoveries. “Apparently, these areas in the Earth’s mantle are much more widespread than previously thought”explains Thomas Schouten, first author and doctoral student at the Geological Institute of ETH Zurich.
For now, researchers are not sure of the nature of these new areas. These anomalies in the lower mantle could have various origins.
“It could be ancient material, rich in silica, which has existed since the formation of the mantle, around 4 billion years ago, and which has survived despite the convective movements of the mantle. Or areas where rocks “rich in iron have accumulated due to these movements of the mantle over billions of years”he emphasizes.
For the doctoral student, this discovery highlights the need for continued research to refine our understanding of the internal dynamics of the Earth.
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