Recent studies using computational modeling predict that the subduction zone currently under the Strait of Gibraltar will expand further into the Atlantic and play a significant role in the development of the Atlantic Subduction System (essentially the Atlantic Ring of Fire). In the geological time frame, this event is expected to occur “soon”, that is, within the next 20 million years.

The oceans seem endless throughout our lives, but they don’t stay there for long: They are born, they grow, and one day they close. This process, which lasts several hundred million years, is called the Wilson cycle. The Atlantic, for example, was born by the breakup of Pangea about 180 million years ago and will one day close. And the Mediterranean is what remains of the great Tethys ocean that once stood between Africa and Eurasia.

Understanding subduction zones

For an ocean like the Atlantic to stop growing and begin to close, new subduction zones must form; places where tectonic plates sink beneath each other. However, subduction zones are difficult to form because the plates must break and bend, and the plates are very strong. The way around this “paradox” is to suggest that subduction zones can migrate from the dying ocean (the Mediterranean) where they currently exist to pristine oceans such as the Atlantic. This process was called subduction attempt.

This study shows for the first time how such direct invasions can occur. The computational gravitational three-dimensional model predicts that the subduction zone currently under the Strait of Gibraltar will extend further into the Atlantic and contribute to the formation of the Atlantic subduction system (Atlantic Ring of Fire), similar to the one that currently exists. structure in the Pacific. In geological terms this will happen “soon”, but not before 20 million years.

The Strait of Gibraltar is a natural physical barrier between the countries of Spain (north) and Morocco (south). Geologically speaking, the 10-mile (16-kilometer) strait that separates the two countries, as well as Europe and Africa, is located where two major tectonic plates (the Eurasian and African plates) meet. Credit: NASA

“Subduction infiltration is inherently a three-dimensional process that requires advanced modeling tools and supercomputers that were not available a few years ago. We can now model in detail the formation of the Gibraltar Arc and how it may develop in the distant future,” explains Instituto of the Faculty of Sciences of the University of Lisbon (Ciências ULisboa) First author João Duarte, researcher at Dom Luiz. (Portugal).

Active diving in Gibraltar

This study sheds new light on the Gibraltar subduction zone, which some authors think is still active and has slowed down significantly over the past millions of years. According to these results, its slow phase will continue for another 20 million years, and then it will accelerate by invading the Atlantic Ocean. This will be the beginning of crustal recycling on the eastern side of the Atlantic, and the Atlantic itself will likely begin to close.

“There are two other subduction zones on the other side of the Atlantic: the Lesser Antilles in the Caribbean Sea and the Scotia Arc near Antarctica. But these subduction zones occupied the Atlantic several million years ago. Studying Gibraltar is an invaluable opportunity because it is in the early stages of the process.” , allows you to observe it while it is still happening,” adds João Duarte.

Overall, this study shows that subduction may be a common subduction initiation mechanism in Atlantic-type oceans and thus plays a fundamental role in the geological evolution of our planet.

The discovery that the Gibraltar subduction is still active also has important consequences for seismic activity in the region. Subduction zones are known to cause the strongest earthquakes on Earth. Events such as the Great Lisbon Earthquake of 1755 pose threats and require preparation.