The Atlantic Ocean could develop its own ‘ring of fire’

The dance of the continents could be about to take a new turn, with the Atlantic Ocean transitioning from a growing to a shrinking phase. Some geologists predict that this will be caused by the breaking of tectonic plates, creating volcanic lines along the coastlines of Africa and the Iberian Peninsula.

Over billions of years, Earth’s continents have come together and fallen apart repeatedly. There is no doubt that this will happen again; What is uncertain is the timing and whether most of the continents will gather at the North Pole or the equator.

Dr. João Duarte of the University of Lisbon leads a team that thinks it can predict both, at least if you offer flexibility on the latter question for several tens of millions of years.

The origins of the Atlantic Ocean date back about 180 million years, when a rift separated Pangea and America moved west and Asia moved east. In addition, subduction zones have formed around the edge of the Pacific Ocean as each continent has forced the edges of oceanic plates into the mantle. This doesn’t happen easily, and these zones have given rise to the Pacific Ring of Fire, home to the most active volcanoes in the world and the largest earthquakes.

For the process to reverse and the Atlantic Ocean to begin to close, new subduction zones would have to form along opposing coastlines. That is not an easy process. Subduction zones require tectonic plates to bend and sometimes break. The process can be self-reinforcing once it gets started, but getting it going is difficult. “The aged oceanic lithosphere is thick and strong, making it resistant to breaking and bending,” Duarte and co-authors write in a new paper.

“The only force that can start a subduction zone is another subduction zone (if you exclude meteorite impacts and supermantle plumes),” Duarte told IFLScience. He and his colleagues argue that the seeds for future subduction zones lie in the western Mediterranean, where an ancient zone brought Africa and Europe together.

If Duarte and colleagues’ models are correct, the largely inactive subduction zone beneath the Strait of Gibraltar will enter the Atlantic Ocean. This will start the process of pulling the Atlantic oceanic plate under Africa and Europe, causing the ocean to close.

“Subduction invasion is inherently a three-dimensional process that requires sophisticated modeling tools and supercomputers that were not available a few years ago. We can now simulate the formation of the Gibraltar Arc in great detail and also how it may evolve in the distant future,” Duarte said in a statement.

The Gibraltar subduction zone was once very active as Africa moved north, but it has faded over the past few million years, causing models of the tectonic future to ignore this zone. However, Duarte concludes that you cannot maintain a good subduction zone forever, and predicts that the newly expanded zone will come back to life in about 20 million years.

One side of an ocean cannot form a ring. It is also unlikely that the Atlantic Ocean would close if this were the only future subduction zone. In the western Atlantic, however, things could change even sooner.

“There are two other subduction zones on the other side of the Atlantic Ocean,” Duarte said in the statement. “The Lesser Antilles in the Caribbean and the Scotia Arc, near Antarctica. However, these subduction zones invaded the Atlantic Ocean several million years ago. Studying Gibraltar is an invaluable opportunity because it allows the process to be observed in its early stages, when it is just happening.”

“The subductions formed [in the west Atlantic] about 50 million years ago and have been slowly moving,” Duarte told IFLScience. “If they want to conquer the opening of the Atlantic Ocean, they will have to spread out and eventually force the Mid-Atlantic Ridge into submission. This could take more than 20 million years.”

It can be assumed that if the Atlantic Ocean closes, it means that the Pacific Ocean will open even further. But: “Everything seems to indicate that the Pacific Ocean will close…,” Duarte told IFLScience. an ocean that could split Africa and Eurasia.”

Duarte thinks the opening of the East African Rift, which will eventually create a new small continent, could be the start of this, along with the rifts within Asia.

The study was published in Geology.

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