A new study led by the University of Southampton and published in the journal Nature shows that a geological phenomenon is causing a rift between the continents of North America and South America from Europe and Africa.
What exactly happens?
Apparently, an increase of matter from the depths of the earth’s crust would be responsible for this widening of the Atlantic and the separation of the continents. Mid-ocean ridges, those mountainous formations that emerge along the seafloor between tectonic plates, may be more involved in the transfer of material between the upper and lower mantle beneath the Earth’s crust than we previously thought, the study emphasizes.
The plates attached to the Americas are moving away from those attached to Europe and Africa by four centimeters per year. Between these continents is the Mid-Atlantic Ridge, a place where new plates are formed and a dividing line between plates that move westward and those that move east; Below this ridge, the material rises to replace the space left by the plates when they separate.
The driving force behind the separation of the Atlantic plates is unknown because the Atlantic Ocean is not surrounded by dense sinking plates, but now, scientists have found evidence of an outcrop in the mantle, the material between the Earth’s crust and its core, from depths of more than 600 kilometers below the Mid-Atlantic Ridge (MAR), which could be pushing the plates from below, causing the continents to separate further. Typically, outcrops below ridges are believed to originate at much shallower depths, around 60 km.
The find came about while they were studying seismic activity around the Mid-Atlantic Ridge. Using up to 39 seismometers deployed on the ocean floor (left for a year to record earthquakes around the world), they found evidence of an outcrop in the mantle from depths of more than 600 kilometers below the SEA. And this upwelling is pushing the tectonic plates from below, causing the continents of Europe and Africa on the one hand and America on the other to move further apart.
The project data provides the first large-scale, high-resolution image of the mantle beneath the SEA , which is known as one of the most turbulent places on Earth due to its seismic activity.
“The incredible results shed new light on our understanding of how the interior of the Earth is connected to plate tectonics, with observations never seen before,” explains Matthew Agius, leader of the work.
“There is an increasing distance between North America and Europe, and it is not driven by political or philosophical differences, it is caused by convection of the mantle! ” Says Nick Harmon, co-author of the study.
While we already knew that mid-ocean ridges contributed to the phenomenon of seafloor expansion , this new discovery shows that the general processes involved extend much deeper into the Earth than previously measured, and may even take place in areas seafloor not marked by open regions of plate subduction.
“Thus, it is likely that mid-ocean ridges play a more active role in plate tectonics than previously thought,” the authors conclude.
The results could help scientists develop better models and warning systems for natural disasters.
Referencia: Matthew R. Agius, Catherine A. Rychert, Nicholas Harmon, Saikiran Tharimena, J.-Michael Kendall. A thin mantle transition zone beneath the equatorial Mid-Atlantic Ridge. Nature, 2021; 589 (7843): 562 DOI: 10.1038/s41586-020-03139-x
