Earth and its continents may have been shifting for longer than scientists previously thought, according to a new study that suggests plate tectonics evolved over the last 2.5 billion years.
This new timeline is contrary to previous studies that said it emerged only 700 million years ago, and it could impact models used to understand how Earth has changed over time.
Plate tectonics is the large-scale motion of parts of Earth鈥檚 crust, and dictates how continents drift apart and come back together. It helps to explain where volcanoes and earthquakes occur, predict cycles of erosion and ocean circulation and how life on Earth has evolved.
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鈥淥ne of the key ways to understand how Earth has evolved to become the planet that we know is plate tectonics,鈥� says Robert Holder at Johns Hopkins University in Maryland. He and his team examined a global compilation of metamorphic rocks that formed over the past three billion years at 564 sites.
On the move
Metamorphic rocks have transformed into a new type of rock through the process of being buried and heated deep in the Earth鈥檚 crust. Because plate tectonics strongly influences heat flow, ancient metamorphic rocks can be used to study plate tectonics in Earth鈥檚 past.
The team compiled data on the temperatures and depths at which the metamorphic rocks formed and then evaluated how these conditions have changed systematically through geological time. From this, they found that plate tectonics, as we see it today, developed gradually over the last 2.5 billion years.
鈥淭he framework for much of our understanding of the world and its geological processes relies on plate tectonics,鈥� says Holder. 鈥淜nowing when plate tectonics began and how it changed impacts that framework.鈥�
Nature
