Surging Matter From Earth’s Mantle Could Be Moving Continents

Scientists found upwellings of material beneath the Earth’s surface from depths far lower than previously known.

Thirty-nine seismometers were deployed on the ocean floor across the Mid-Atlantic Ridge as part of the PI-LAB experiment. (The University of Southampton)

(CN) — Material welling up from the Earth’s mantle could be slowly moving North and South America away from Europe and Africa, according to a study published Wednesday.

Between those four continents, and the tectonic plates they are attached to, is the Mid-Atlantic Ridge, where new plates are formed. In the study published in Nature, a team of researchers from the University of Southampton and the University of Oxford say they discovered evidence of upwellings in the Mid-Atlantic Ridge from depths far deeper than such upwellings have been previously thought to originate.  

Plate tectonics is a scientific theory that describes the movement of seven main plates and a multitude of smaller plates of the Earth’s crust and the upper mantle, also known as the lithosphere. The movement of tectonic plates can change the Earth’s landscapes, creating trenches and mountains as they jostle beneath us, diverging and converging, and can cause earthquakes, tsunamis and volcanic eruptions. 

Most activity occurs along tectonic plate boundaries, more commonly known as faults. 

As the plates they sit upon move, the Americas, Europe and Asia have been drifting away from each other by a few centimeters a year. In the Mid-Atlantic Ridge, material rises up to replace the space left by the plates as they move apart. 

The authors of the study — led by Dr. Kate Rychert and Dr. Nick Harmon from the University of Southampton, and Professor Mike Kendall from the University of Oxford — say that the general belief is that denser plates return into the Earth and in turn, new lithosphere is created. But without any nearby sinking plates, it’s a mystery as to what makes the Mid-Atlantic Ridge work.

In two experiments — the PI-LAB (Passive Imaging of the Lithosphere-Asthenosphere Boundary) experiment and EURO-LAB (Experiment to Unearth the Rheological Oceanic Lithosphere-Asthenosphere Boundary), the scientists ventured out on two research cruises, the RV Langseth and RRV Discovery, and released 39 seismometers into the Atlantic. They obtained images of the underlying mantle and never-before-seen details. 

The images showed evidence of upwelling, or rising, of matter within the mantle approximately 373 miles below the ridge. This could be the invisible force behind the continental drift. 

“There is a growing distance between North America and Europe, and it is not driven by political or philosophical differences — it is caused by mantle convection,” Harmon said in a statement with the release of the study.

The authors note that this is a unique occurrence as upwellings typically thought to occur at depths closer to 37 miles.

“This was completely unexpected. It has broad implications for our understanding of Earth’s evolution and habitability. It also demonstrates how crucial it is to gather new data from the oceans,” Rychert said in the statement. “There is so much more to explore!”

Not only does this study provide important new information on plate tectonics, but it was also one of the first of its kind to be conducted in the ocean, providing much more hands-on data. They were able to capture images of the upwelling and see its effects at different depths and gain abundance of clear evidence.

The scientists said the scale of the experiment was unique and allowed them to explore variations in the structure of the Earth’s mantle of depths associated with changes in mineral phases.

“This was a memorable mission that took us a total of 10 weeks at sea in the middle of the Atlantic Ocean. The incredible results shed new light in our understanding of how the Earth interior is connected with plate tectonics, with observations not seen before,” said the study’s lead author, Matthew Agius, a former post-doctoral fellow at the University of Southampton and currently at Università degli studi Roma Tre.

The team hopes that their work will help give seismologists a better understanding of plate tectonics, which has significant impacts on life above the Earth’s crust. The authors added that they believe their findings could assist experts in making climate change predictions. 

“This work is exciting and that it refutes long held assumptions that mid-ocean ridges might play a passive role in plate tectonics. It suggests that in places such as the Mid-Atlantic, forces at the ridge play an important role in driving newly-formed plates apart,” Kendall said. 

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