Newly discovered Atlantic subduction zone raises geological intrigue

The latest geological research has unveiled that instead of two, there are three subduction zones beneath the waters of the Atlantic Ocean. Interestingly, the zone nearest to Europe draws particular attention.

The study, published in the journal Geology, sheds light on the subduction zone located near the Strait of Gibraltar. Commonly referred to as the Gibraltar Arc or trench, this area bridges the narrow marine gap between Portugal and Morocco. It is on a westward expansion path, raising concerns among scientists that it could eventually extend into the broader Atlantic Ocean.

While the Lesser Antilles in the Caribbean and Scotia near Antarctica are well-documented Atlantic subduction zones, the zone straddling Europe and Africa presents a crucial opportunity for study due to its relatively recent formation.

"The previous two zones began affecting the Atlantic several million years ago. The Gibraltar zone allows us to witness such a process from its inception," states João Duarte, a geologist at the University of Lisbon and the lead author of the study.

The team of Portuguese researchers suggests that the current period of inactivity may persist for another 20 million years. After this hiatus, they predict that the Gibraltar arc could resume its push into the Atlantic, a phenomenon they term "subduction invasion."

Subduction zones, where lithospheric plates converge and one is forced below the other, play a critical role in plate tectonics. Unlike convergent boundaries, which push towards one another, subduction zones concern the downward motion of one plate beneath another.

The Gibraltar arc presents an intriguing case of being "trapped" for approximately the last 5 million years. Driven by curiosity about its current state of activity, João Duarte's team utilized a detailed computer model to reconstruct the arc's development from its origins in the Oligocene epoch to the present day.

Their model revealed a significant decrease in the arc's activity about 5 years ago as it neared the Atlantic edge. Forecasting up to 40 million years into the future, they envision the arc navigating through the confined straits of Gibraltar for another 20 million years.

Should the Gibraltar arc extend into the Atlantic, it might spearhead the creation of a new Atlantic subduction system. This could potentially mirror the extensive subduction chain surrounding the Pacific Ocean and, among other ramifications, elevate the Strait of Gibraltar, thereby altering the Atlantic's structure.