In recent days, we have been able to see some voices that pointed to an almost apocalyptic event in our country: the Strait of Gibraltar this “about to disappear“, making two continents come together. The image in this case is quite powerful: the Mediterranean turning into a salt lake or completely disappearing before our eyes because its water intake would be cut off. However, when geologists say ‘soon’, they don’t mean next week.
The reality. This new wave of fear over this fact arises as a result of a publication in the magazine Geology which is undoubtedly fascinating. In this case, geologists have used the capacity of supercomputers and 3D geodynamic models to see that under Gibraltar there is a subduction zone that right now she is ‘asleep’ and could wake up at any moment.
The study, led by João C. Duarte together with researchers from the University of Mainz, addresses one of the great debates in plate tectonics: is the Gibraltar subduction zone dead?
The discovery. For years science has pointed out that the sinking of the oceanic lithosphere under the Gibraltar Arc had stopped. However, the authors have applied new computer simulation techniques with the 3D ‘gravity-driven’ model to be able to reproduce the evolution that the western Mediterranean will follow where this strait is located.
This is something fundamental, since the ancient models had us quite limited, but with technology you can see the processes over millions of years. The result of what was seen is quite clear: subduction is not dead, but is in a period of ‘rest’ or ‘silence’. Although the model believes that at some point this is something that will be activated or unblocked again.
The future of the Atlantic. Something that must be clear is that the oceans are not static, but rather follow what is known as the Wilson Cycle. According to this model, the Atlantic is a young ocean that is expanding right now.
But like everything in this life, it is doomed to die, just as happened in the past with the Tethys ocean, which is the ancestor of the Mediterranean Sea. However, for this to occur, subduction zones need to be activated where the tectonic plate sinks under another.
breaking plates. The problem is that breaking a tectonic plate to start this subduction process is mechanically very difficult. The solution proposed by this team is that this area already exists in the Mediterranean, and its effect will spread to the west, crossing the Strait and invading the Atlantic.
This is something that would give something called the ‘Atlantic Ring of Fire’, analogous to the famous Pacific beltcharacterized by volcanoes and earthquakes.
When will this occur? This is where the important nuance comes in that must be taken into account when we talk about something in geology happening ‘soon’. According to this simulation, the current phase of inactivity will last for some time yet. But not a few days, but the propagation of subduction towards the Atlantic will gain traction in 20 million years and the development of the new subduction system can be delayed up to 50 million years.
Saying that the Strait is “about to disappear” based on this study is like saying that the Sun is about to go out because it has “only” fuel left. 5 billion years. It is true on the scale of the universe, but irrelevant to our daily lives.
Why it is important. Beyond the time it will take for this to occur, this model demonstrates how subduction zones can migrate from dying oceans like the Mediterranean to expanding oceans like the Atlantic, helping us understand how the Earth has been shaped throughout its history.
Images | Malcolm Ketteridge
GIPHY App Key not set. Please check settings