In an unprecedented revelation, a 2021 study has discovered that the tectonic plates beneath the Americas are separating from those beneath Europe and Africa, resulting in the Atlantic Ocean growing wider by 1.5 inches every year. This groundbreaking discovery unravels an intriguing mystery that has long baffled scientists, particularly because the Atlantic does not possess the same dense, subducting plates found in the Pacific. The key to this remarkable expansion, according to the study, lies beneath a large underwater mountain range known as the Mid-Atlantic Ridge (MAR), located in the middle of the ocean.
The study, published in the esteemed journal Nature, reveals that material from deep within the Earth is rising to the surface under the MAR, thereby forcing the plates on either side apart. This fascinating phenomenon of seafloor spreading occurs at divergent tectonic plates that are pulling apart like the MAR. Typically, any material rising under tectonic boundaries like the MAR originates from the mantle very close to the Earth’s surface, however, the researchers identified that the MAR is a convection hotspot, with magma and rock from 410 miles under the crust pushing their way to the surface. This unexpected revelation has been described by experts as "exciting" and "completely unexpected".
The Atlantic Ocean Expands: A Geologic Mystery Solved
A Deep Dive into Tectonic Movement
Tectonic plates under the Americas, Europe, and Africa continue to separate as the Atlantic Ocean expands by 1.5 inches every year. For long, scientists were puzzled about the cause of this movement since the Atlantic lacks the dense, subducting plates found in the Pacific. However, a 2021 study published in the journal Nature has shed new light on this topic. The researchers suggest the key lies beneath the Mid-Atlantic Ridge (MAR), an underwater mountain range in the middle of the ocean, which separates the North American plate from the Eurasian plate, and the South American plate from the African plate.
A Phenomenon Unearthed
Beneath the Earth’s crust lies a 1,800-mile-thick mantle that surrounds the core, as hot as the surface of the sun. The Earth’s crust, fragmented into tectonic plates, fits together like a puzzle. These plates interact in various ways, moving together or apart, or sliding under one another. Magma can bubble up from inside the Earth through volcanoes or seafloor spreading at divergent tectonic plates such as the MAR. Convection currents can also pull hot, softened rock from the mantle towards the surface.
Unusually, the researchers found that the MAR is a convection hotspot where material from 410 miles under the crust can push their way to the surface. This upwelling of material is what is spreading the tectonic plates, and the continents on top, apart. "This is what makes this result exciting because it was completely unexpected," said Matthew Aguis, a seismologist at Roma Tre University and a co-author of the study.
Usually, material trying to ascend from the lower to upper mantle is obstructed by a band of dense rock known as the mantle transition zone, located between 255 miles and 410 miles under our feet. However, Agius and his colleagues discovered that beneath the MAR, temperatures in the deepest part of the transition zone were higher than expected, thinning the zone. As a result, material can rise to the ocean floor more easily there than in other parts of the Earth.
Unraveling the Mystery
This discovery has helped solve a long-standing geological conundrum. Typically, plates move under the force of gravity as it pulls denser parts of plates into the Earth. But the plates surrounding the Atlantic Ocean are not as dense, leaving scientists puzzled about what triggers these plates to move if not gravity. The research suggests that the upwelling of material from deep within the mantle could be driving the Atlantic expansion.
Geophysicist Catherine Rychert, another co-author of the study, hypothesizes that this process started 200 million years ago. However, she suggests that the rate of expansion could increase in the future. "Most probably the rate will remain the same during our lifetime. However, it is likely the rate will change over millions of years because it has varied in the past," Rychert told Insider.
This groundbreaking study offers a fresh perspective on how the world’s oceans are expanding. By revealing that the Atlantic Ocean’s expansion is driven by material rising from deep within the Earth, it provides a novel understanding of the intricate workings of our planet’s geology. The findings also raise exciting possibilities about future shifts in the Earth’s geological landscapes, with implications for climate science, natural disaster prediction, and resource exploration. As we continue to explore the depths of our planet, we can expect many more such revelations about the forces shaping our world.