Study Finds Ancient Continent Moved at “Crazy Fast” Speeds Billions of Years Ago
New research led by Dr. Jennifer Kasbohm of Yale University has shed light on the speed at which tectonic plates moved billions of years ago. The study, which analyzed ancient magnetic fields and dated rocks from Western Australia’s Pilbara Craton, suggests that this early continent moved at astonishing speeds of up to 64 centimeters (25 inches) per year, far exceeding today’s fastest plate motion of around 12 centimeters (4.7 inches) per year.
Tectonic plate movements have significant implications for the planet’s history, influencing everything from the supply of crucial nutrients for early life to the rise of oxygen. However, it has remained unclear whether the hotter temperatures of Earth’s early history resulted in faster plate movements due to a squishier mantle or less water content in the mantle, which slows down plate motion.
The research focused on the Archean eon, which predates current plate tectonics. At that time, basalt lava flows covered what is now Western Australia, similar to the volcanic activity seen in present-day Iceland and Hawaii. The study aimed to understand the nature of Archean plate tectonics by analyzing precise data on how the basalt formations occurred and measuring the Earth’s magnetic field preserved in these ancient rocks.
Finding suitable samples for analysis proved challenging, as the rocks are extremely old, vulnerable to geological events that could alter their magnetic fields over billions of years. Despite these difficulties, Kasbohm and her team were able to obtain four relevant dates and magnetic field measurements, allowing them to track the Pilbara Craton’s movement over four points in time.
The resulting data revealed that the Pilbara Craton experienced significant movements, shifting from a latitude of approximately 51 degrees to 68, then 76, and finally back to 49 degrees over the span of 10 million years. The researchers estimate that the averaged speed during this period was 64 cm per year, making it one of the fastest plate motions ever recorded.
However, the study’s findings may still be an underestimate, as the data only accounts for movement along latitudes and not East-West directions. Given that plates can change longitudes as well, it is plausible that the Pilbara Craton covered even greater distances and moved even faster than the recorded 64 cm per year.
The discovery of such rapid plate motion during the early Earth challenges the notion that plate movements have remained constant over time. According to Professor Alan Collins of The University of Adelaide, who was not involved in the study, “Kasbohm and co-authors have produced a lovely piece of work that confirms what many of us have suspected for a while now: in the early Earth, plate tectonic speed was anything but uniform.” These findings have far-reaching implications for our understanding of the planet’s geological history and its influence on the development of life.