Plate tectonics evolution unlocked

Researchers from Germany and Switzerland have shown, with the aid of computer simulations, how plate tectonics occurred on Earth.

Scientists know that the Earth formed 4.6 billion years ago, but are less certain of when its crust materialised. Even though the young planet possessed both continents and oceans, there may have been no plates and therefore, no plate tectonics.

Professor Sumi Chakraborty, from Ruhr University Bochum and study co-author, said: “These properties render the Earth habitable. We haven’t found anything comparable anywhere else in the universe.” The emergence of plate tectonics on Earth is hotly disputed and is one of many unanswered questions in geophysics.

Understanding plate tectonics

The scientists’ computations estimate plate tectonics may have begun three billion years ago. They also show that the planet’s earliest continental crust, rich in iron and magnesium, was destroyed two or three billion years ago, resulting in the current, silicon-rich, continental crust.

Professor Chakraborty’s research group also discovered that during the planet’s formative years, continents were constantly recycled. Continental recycling still occurs, but over a longer period of time in a different manner. Priyadarshi Chowdury, also from Ruhr University, said: “Over time, the continental crust became prone to preservation during continent-continent collision.” In the past, thin layers peeled off from the Earth’s crust – now chunks of continental crust break off in areas where plates collide.

The researchers believe that the destruction of the early continental crust was crucial for present day crust’s formation, and it may have been the reason why these continents could rise so high above sea level. Chowdhury said: “These changes to the continental character might have contributed to the Great Oxygenation Event on Earth – and, consequently, to the origin of life as we know it.”

The researchers at Ruhr worked alongside Professor Taras Gerya from the Swiss Federal Institute of Technology in Zurich. Their research was published in Nature Geosciences.