This is one of Earth’s many unique features: unlike other known planets in the universe, Earth’s surface is composed of rigid plates that slide, collide with each other, and sink into the planet’s interior.
But when did the Earth’s surface break up into tectonic plates? And when did these plates start moving? This is an important question because plate tectonics appears to drive the evolution and complexity of life.
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Surprisingly, geologists don’t have a good answer to the question of when plate tectonics emerged, with estimates ranging from 700 million years ago to about 4 billion years ago, when Earth was still in its infancy.
The oldest clear evidence of modern plate tectonics comes from the Neoproterozoic (1 billion to 541 million years ago), Robert Stern subduction zones
However, many geologists consider Stern’s view too conservative.
Critics agree that rocks indicative of plate tectonics first became widespread 700 to 900 million years ago. However, they suggest that these rocks may have existed earlier and been eroded by time.
For example, the Indian subcontinent collided with southern Asia just 55 million years ago, and many of these rocks have already eroded away, he says Mark Harrison
Stern says there is evidence for a small subduction episode 1.8 billion years ago that didn’t quite last
Many researchers considered the transition to plate tectonics much earlier. There are many indications of some type of geological shift during the Archean Eon (4 billion to 2.5 billion years ago), with estimates placing the exact period at 2.5 billion to 3.8 billion years ago. For example, at least one ophiolite has been preserved dates back 2.5 billion years
Other evidence is the chemistry of the crust. If the crust is completely new volcanic rock, its chemical composition will resemble the mantle from which it comes. If it is melted down and recycled by plate tectonics, this chemistry will change. Some influential 2012 study Chris Hawkesworth
Research on zircons – minerals that survive even after the rocks around them melt and deform – suggest that the Earth’s crust moved earlier, around 3.8 billion years ago Nadja Drabon
But does this transition reflect true plate tectonics? Zircon research published in 2023
Drabon noted that it is possible that different aspects of plate tectonics emerged at different times. Subduction may have started 3.8 billion years ago, but it took some time for the continents to start drifting around the globe.
A newer and more controversial idea suggests that Earth developed plate tectonics during the Hadean (4.5 to 4 billion years ago). This idea comes from growing evidence that the newborn Earth was a surprisingly modern-looking place with oceans and continents – a conclusion drawn from zirconium research chemistry of the oldest preserved rocks on Earth they look uniquely like zircons that form in volcanic arcs plate tectonics existing in Hadesian conditions
Each piece of evidence supporting each of these origin stories has weaknesses. For example, the vast majority of very old zircons come from one place, Jack Hills in Australia, and may not reflect what was happening on the rest of the planet. The oldest rocks may also be strange – perhaps they still hang around because they were unlike any other rocks on ancient Earth. And you don’t want to step in the middle of computer modelers as they argue about assumptions about the state of the mantle 4 billion years ago.
“It’s shocking to realize that there is no consensus on when (plate tectonics) began.” Jesse Reiminek
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