The earliest evidence of plate tectonics on Earth has been discovered, revealing that this geological process may have begun shaping the planet billions of years ago, reports BritPanorama.
Scientists, led by Professor Roger Fu from Harvard University, published their findings in the journal Science on March 19. They argue that understanding when plate tectonics first occurred is vital to explaining Earth’s geological features, such as mountains and oceans. “Trying to understand when it happened on early Earth makes everything else make sense,” Fu remarked.
Plate tectonics today consists of seven major and eight minor tectonic plates, each averaging about 125 kilometers (80 miles) thick, moving several centimeters each year. Their interactions, particularly at the margins where volcanic activity and earthquakes frequently occur, shape the dynamics of the planet.
Debate exists within the scientific community regarding the origin of plate tectonics, with some proposals dating back to 4.4 billion years ago, while others suggest a more recent onset within the last billion years. The researchers indicate that the first moving plates were likely formed during the Archean Eon, approximately 3.5 billion years ago, a time when Earth’s surface already supported early microbial life. This revelation could contribute to understanding the conditions that facilitated life’s early development on the planet.
Rocks capture Earth’s early history
Fu and his team studied rock samples from the East Pilbara Craton in Western Australia, an area noted for its rich fossil evidence, including early life forms like stromatolites. They applied the scientific method of paleomagnetism to analyze the rock samples, which allowed them to determine the original orientation and latitude of these ancient deposits.
By analyzing 900 rock samples representing a 30 million-year timeframe, the team discovered that part of the formation had shifted significantly in latitude and rotated over time. The researchers also compared these findings with data from the Barberton Greenstone Belt in South Africa, which remained largely stationary during the same period.
Lead author Alec Brenner emphasized that these findings challenge the notion of a stationary lithosphere, suggesting instead that Earth’s crust was segmented into active, movable pieces as opposed to a single, continuous shell. The movement of tectonic plates marks a fundamental shift in our understanding of Earth’s geological evolution.
This study’s significance lies in the quality and quantity of paleomagnetic data gathered from such ancient rocks, as highlighted by Uwe Kirscher, an independent researcher. He noted the importance of this study in illustrating the relative motion of Earth’s plates during critical transitional periods, providing crucial evidence of how Earth evolved toward its current geological state.
