Researchers at the University of British Columbia have opened a new window into Earth’s distant past, revealing a key chapter in the formation of continents billions of years earlier than previously thought.
Contrary to established belief about the role of plate tectonics, the team of scientists delved deep into ancient rocks to unlock the secrets of the Earth’s early crust.
The study that reveals the formation of the first continents
The ‘bricks’ of the Earth’s early crust, known as granitoid rocks, played a crucial role in this geological enigma.
Called tonalite, trondhjemite and granodiorite (TTG), they came together between 4 billion and 2.5 billion years ago, but the exact process remained an intriguing mystery.
Contrary to previous belief, researchers have ruled out the influence of plate tectonics at this early stage in the composition of continents.
Instead, they focused on elements preserved in rocks that carried signs unchanged from the pre-plate tectonic era.
Tectonic plates today – Image: Reproduction
Published in the renowned journal Nature Communications, the study debunks the theory that plate tectonics were responsible for bringing together ancient rocks in the first subduction zones.
The research revealed that the process was much older, with the constitution of the Earth’s crust resembling a gabbro with a basaltic composition, currently known as black granite.
Intriguingly, such pre-continental crust is still present on modern continents, such as the majestic Appalachian mountain ranges in the USA and Canada.
The study suggests that these rock formations resulted from a process of slow sinking, thickening and melting of pre-existing crust, possibly evoking modern oceanic plateaus.
In-depth analysis of the chemical changes preserved in TTG has led scientists to discredit the theory that ancient rock unions emerged in the first subduction zones and marked the birth of plate tectonics.
Furthermore, the hypothesis of meteorite impacts as catalysts for the formation of current continents has been discarded.
The discovery not only redefines our understanding of the composition of continents, but also highlights the persistence and wealth of information that ancient rocks hold about Earth’s beginnings.
TTG samples cataloged over decades were crucial pieces in this geological puzzle, shedding light on events that shaped the planet much earlier than we imagined.
2024-02-12 11:21:06
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