Cracking Continents: The Power of Mantle Plumes

When a volcano forms in an area that is otherwise tectonically stable, it may be safe to assume that a mantle plume is to blame. These columns of volcanic material are thought to rise from the boundary layer of the Earth's core, putting extreme pressure on the underside of the Earth's crust. It has been suggested that these theoretical plumes even break up continents, contributing to the distribution of land across Earth's oceans that we see today.

A study recently published in the journal Nature details how plumes may cause massive rift systems where they otherwise should not be. However, other geologists have long argued that these theoretical plumes don't even exist.

As is often the case in geology, many natural phenomena can be disputed simply because they take far too long to be directly observed, even by generations of scientists. Instead, their potential results and consequences must be measured in the hopes of better understanding the process as a whole.

That's exactly what Evgueni Burov and Taras Gerya did in their latest work, creating a high-resolution 3D model of the Earth's surface in the hopes of displaying why mantle plumes likely exist, and how they shatter continents.

Interestingly, the model showed that mantle plumes can only crack continents under very specific conditions.

"The force exerted by a plume on a plate is actually too weak to break it up," Gerya explained in a press release.

Gerya compared mantle plumes to a finger poking at saran wrap from below.

"Weak, pointed force is enough to tear the film, but if the film is not pulled taut, it is extremely difficult to tear."

That kind of tautness is called tensile stress and can be caused by the force of tightly locked and overlapping tectonic plates - the complete opposite of where most volcanic activity occurs. However, such stress combined with a plume may actually escalate the speed of geological activity. According to the model, rift systems can be created by plume pressure after a "mere" two million years - that's about 50 times faster than the formation of something like the Alpine orogeny.

After the creation of his model, Gerya added that he thinks it is "much more likely" that plumes exist.

"We know the rules, but humans generally lack the intuition to identify how they interact on geological timescales."

The model, he says, can help.