A mysterious phenomenon could make the Atlantic Ocean grow bigger every year

The oceans are not as level as you might think. Scientists estimate that the Atlantic Ocean is actually widening by several inches each year. At the same time, the Pacific is shrinking.

This glacial slow movement of the oceans is due to the continuous movement of the Earth’s tectonic plates, as the plates under the Americas separate from those under Europe and Africa.

The deep geophysical forces underlying this epic phenomenon remain far from fully understood, but researchers may have just identified a significant contributor to what is happening.

In a new study, scientists suggest that mid-ocean ridges – mountainous formations that emerge along the seabed between tectonic plates – may be more involved in the transfer of matter between the upper and lower mantle beneath the earth’s crust than we never thought so before.

The 39 locations of the seismometers. (University of Southampton)

“Sinking slabs and ascending plumes are generally accepted as transfer locations, while mid-ocean ridges are generally not supposed to play a role,” says a team led by seismologist Matthew Agius of the University of Southampton in the UK in a new article.

“However, strict constraints in situ measurements at the peaks proved difficult. “

To fill the gaps in our knowledge, the researchers deployed a fleet of 39 seismometers along the bottom of the Atlantic to record seismic motions under the Mid-Atlantic Ridge – the border of the ridge that tectonically separates the Americas from the Europe and Africa.

The seismic readings recorded in the experiment monitored the flow of material in the mantle transition zone that lies between the upper mantle and the lower mantle, which allowed the team to imagine material transfer at depths of up to 660 kilometers (410 miles) below the surface.

The results suggest that upwelling chemical matter is not limited to shallow depths of the Mid-Atlantic Ridge, but may emerge at the deeper ends of the mantle transition zone, suggesting that the material from the lower mantle is rising upward. .

“The observations involve a transfer of matter from the lower mantle to the upper mantle – either continuous or punctuated – which is linked to the mid-Atlantic ridge,” the researchers explain.

“Given the length and longevity of the mid-ocean ridge system, this implies that entire mantle convection may be more widespread than previously thought.”

Deployment of one of the seismometers. (University of Southampton)

While mid-ocean ridges were previously known to contribute to the seabed sprawl phenomenon, the new findings show that the global processes involved extend much deeper into the Earth than has been previously measured, and may still occur even in areas of the seabed not marked by overt regions of plaque subduction.

“[The work] refutes long-held assumptions that mid-ocean ridges may play a passive role in plate tectonics, ”says researcher and geophysicist Mike Kendall of the University of Oxford.

“This suggests that in places such as the mid-Atlantic, ridge forces play an important role in separating the newly formed plates.”

The results are reported in Nature.