A new study has changed what scientists thought they knew about Earth’s early history.
Researchers have discovered that the very first crust of our planet, formed about 4.5 billion years ago, already had chemical features similar to the continents we see today.
This surprising finding means that some long-held ideas about how continents formed and when plate tectonics began may need to be revised.
The study, published in the journal Nature, was led by Professor Emeritus Simon Turner from Macquarie University in Australia, along with researchers from the UK and France.
For many years, scientists believed that the chemical signature of continental crust—especially its low levels of the element niobium—was created by plate tectonics.
This process involves large plates of the Earth’s surface moving and sliding beneath one another, forming new rock in special areas called subduction zones.
But the new research shows that this unique chemical fingerprint may have existed long before plate tectonics began.
Turner and his team used advanced computer models to simulate the conditions on Earth shortly after it formed.
At that time, the planet was covered by a deep ocean of molten rock, and the core was still forming.
Their models showed that under these early conditions, the element niobium would have been drawn into the core because it was attracted to metal.
This would naturally leave the early crust with low levels of niobium, creating the same chemical signature found in continental rocks today—even without any plate tectonics.
This first crust, known as “protocrust,” likely broke into pieces over time. Some parts thickened to form the beginnings of continents, while others were destroyed or recycled due to meteor impacts and early plate-like movements.
These natural processes eventually led to the kind of crust we see today in both continents and oceans.
Meteor impacts played a big role in shaping early Earth. They likely caused the crust to melt, move, and change shape. Plate tectonics may have started and stopped during this chaotic time.
It wasn’t until about 3.8 billion years ago—when meteor strikes became less frequent—that plate tectonics began operating in a more steady and self-sustaining way.
“This changes how we understand Earth’s first steps as a planet,” said Professor Turner. “It also gives us new ideas about how continents might form on other planets in the universe.”
Source: Macquarie University.
