The Atlantic Ocean is broadening, shaking America on one side and Europe and Africa on the other. But it is not known exactly how.
A new study reveals that deep beneath the Earth’s crust, in a layer called mantle, hot rocks are rising and thrusting on tectonic plates – the rocky saw fragments that make up the Earth’s crust – that form the Atlantic Let’s meet below.
Earlier, scientists thought that the continents were being pulled apart mostly because the plates under the ocean went in opposite directions and crashed into other plates, folding under the force of gravity. But new studies show that this is not the whole picture.
The research began in 2016, when a group of researchers set sail on a research vessel for the largest part of the Atlantic Ocean between South America and Africa; In other words, “in the middle of nowhere”, said lead author Matthew Agius, who at the time was a postdoctoral researcher with the University of Southampton in the UK, but now at Roma Trey University in Italy.
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The spot is not a particularly popular route for travel, Agius said, noting that sometimes days will pass without seeing a single ship or aircraft. Interaction is limited to occasional whales and dolphins that swim through the ship’s Wi-Fi and is a fleeting signal. The Lightless Nights blanketed the vast sea in an unobstructed view of the Milky Way and the stars – and it’s very, very calm, Agius said.
But this vast, empty stretch of ocean rests on an incredibly important geological location: the Mid Atlantic Ridge, the planet’s largest tectonic boundary that extends 10,000 miles (16,093 kilometers) from the Arctic Ocean to the southern tip of Africa. This is where the South American and North American plates separate the Eurasian and African plates at a speed of about 1.6 inches (4 cm), extending the Atlantic Ocean.
Agius and his team spent five weeks exploring seismic waves (seismic-like waves or vibration-detecting instruments from seismographs), about 621 miles (1,000 km) across a small part of the ridge.
A year later, researchers collected seismometers.
Until now, “we never had good images of what’s happening under the sea,” Agius said. Since seismic waves behave differently depending on the material they pass through, researchers can use them to create data from which they can coalesce into different layers of the Earth. In that year of listening, seismic earthquakes raised the vibrations of earthquakes coming from different parts of the world and through the deepest churn of the Earth – a layer of solid, warm rock about 1,800 miles (2,900 km) thick.
While the team’s original goal was to find out how the plates were born and how they aged, and they actually intended to study the shallow depths of the Earth, researchers found evidence for a deeper phenomenon in the play.
They found that in the area within the ridge, the mantle transition zone – a high-density zone that acts as a gatekeeper between the upper and lower layers of the mantle – was thinner than average, meaning that it was thinner than normal. It was hot. Agius stated that the warmer temperature of the transition zone facilitated the “upwelling” of the hot rock from the Earth’s lower Earthworm, which actively separated the plates.
Agris said the researchers first thought that the plates separated from each other mainly due to “pullings” in the subduction zone, colliding the plates and sinking beneath each other, pouring the recycling material into the mantle. So if you have one plate being pulled on one side (and crashing with another plate in a subduction zone), and another plate being pulled on the other side (crashing again with another plate in a subduction zone ), This will create ridges in the middle, where hot material rises from the bottom to fill the resulting gap.
“It’s still happening, but it was thought that ridges are an effect of that process,” he said. But their findings suggest that as subduction zones separate the plates, the runoff below the ridges may actively help to separate them. However, it is unclear whether this process is related only to the Mid Atlantic Ridge or if all ridges around the world experience the same thing, Agius said. “Pulling is still left, just we now want to determine if all the streaks are pushing too.”
Push and pull
“The findings” add to the puzzle to understand the flow in the Earth’s mantle, which was not part of the study, said Joren Ritsima, a professor in the Department of Earth and Environmental Sciences at the University of Michigan.
Although his analysis is “excellent”, the study is limited in scope, he said. He observed only a small portion of the Atlantic seafloor, so it is unclear whether his findings would be correct with the entire Mid-Atlantic Ridge or even other mid-ocean ridges. “From a single point of view it is difficult to estimate the global level of rock flow in the Earth’s mantle,” Ritema told Live Hisin. “It’s like peeping through a keyhole and trying to figure out what furniture is upstairs in the living room, kitchen and bedroom.”
What’s more, there may be some other explanations for the warm-normal transition zone.
This is a very “remarkable data set they have collected in great pain”, said Barbara Ramonowicz, professor at the University of California, Berkeley’s Graduate School of Earth and Planetary Sciences, and professor emeritus of the College de France in Paris, which is also a Was not part of the study. “I have no doubt about his analysis … I have reservations about his explanation,” Ramonovich told LiveScience. He said that there are famous plums nearby that can be offset and cause that area to overheat.
Vedran Lesik, an associate professor in the Department of Geology at the University of Maryland, who was also not involved with the study, agrees that his explanation is plausible “but not the only one possible to explain the findings.” But if the conclusion is repeated elsewhere, it “may question our prevailing view of the streaks,” he said.
These and other similar findings may also change our map. Some 300 million years ago, all seven continents were smooched together into a single supercontinent. Pangea. Over millions of years, the plates divide continents, creating ocean boundaries and modern maps. But the spread of the Atlantic Ocean and the shrinking of the Pacific Ocean are gradually inconsistently aging those maps and making them increasingly inaccurate. “The map will change a bit [for now] And that will change drastically over millions and millions of years, ”Agius said.
The findings were published in the journal Nature On 27 January.
Originally published on Live Science.