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This is due to the continuous movement of the Earth’s tectonic plates, as the plates below North and South America differ from those of Europe and Africa.
The deep geophysical forces underlying this epic phenomenon are far from fully understood, but researchers may have identified an important factor in determining what is happening.
In a new study, scientists suggest that the oceanic ridge, the mountainous formations that form along the seafloor between tectonic plates, could be more involved in the transfer of matter between the upper and lower mantles beneath the Earth’s crust. than we believed.
“Sinking plates and rising magma foci are generally acceptable as relocation sites, while the mountain range in the middle of the ocean often plays a role,” explains a team from the University of Southampton in the UK led by the seismologist. Matthew Agius.
“It just came to our knowledge then in the place measurements on the ridges turned out to be difficult ”.
To fill our knowledge gaps, scientists deployed a park of 39 seismometers along the Atlantic floor to capture the seismic movements below the Mid-Atlantic Ridge, the border of the range that tectonically separates North and South America from Europe and Africa.
The seismic readings recorded in the experiment monitored material flow in the mantle transition zone between the upper and lower mantle, allowing the team to visualize material transfer deep underground, even 660 kilometers below the surface. .
The results suggest that chemical uplift is not limited to shallow depths in the mid-Atlantic ridge, but may occur at the deeper edges of the mantle transition zone, suggesting that lower mantle material rises upwards.
“The observations mean that the material is moving from the lower mantle to the upper, continuous or fissile, which is associated with the mid-Atlantic ridge,” the researchers explain.
“Given the length and longevity of the oceanic ridge, this means that convection throughout the mantle may be more frequent than previously thought.”
Although the oceanic ridge was already known to have contributed to the seafloor expansion phenomenon, the new findings suggest that all related processes are taking place much deeper than previously measured, and can still occur even in seafloor areas. marine that are not marked by open areas. plains, subduction regions.
“This work refutes the old assumption that the oceanic ridge may play a passive role in plate tectonics,” said Mike Kendall, principal investigator and geophysicist at the University of Oxford.
“This shows that places like the mid-Atlantic ridge play an important role in the movement of the newly formed plates.”
The results of the study are described in Nature.
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