Plate tectonics, which causes continental drift, mountain creation, and earthquakes, likely began around 4 billion years ago, according to a recent study. This discovery dates plate tectonics to the Hadean era, shortly after Earth’s birth, 4.5 billion years ago.
Earth was molten and volatile, with an ammonia and methane atmosphere in its primordial state. Though hot, the atmosphere held enough water to form a worldwide ocean as the planet cooled. Tectonic plate grinding during cooling resulted in the formation of a solid outer crust.
Scientists discussed plate tectonics’ beginning. It may have started with the crust cooling in the Hadean epoch. Some said 3.2 billion years ago, when the crust’s composition changed, while others said contemporary plate tectonics only formed in the last couple of billion years.
Plate tectonics timelines are difficult to determine since rocks older than 4 billion years are scarce. However, researchers used 4.4 billion-year-old zircon crystals. S-type zircons, generated in sedimentary rocks on land and recycled by tectonic activity, gave significant clues.
A machine-learning technique was used to classify 300 zircons and test 74 more for S-type in the newest PNAS study. About 35% of Jack Hills zircons were S-type, with some dating back 4.2 billion years. This shows plate tectonics moved rocks from the crust to the mantle and back during the Hadean.
This new study redefines Earth’s geological history and highlights the dynamic forces that have altered our planet since its birth.
