Early Subduction on Earth
Groundbreaking discovery: Early subduction on Earth linked to Theia impact and Moon formation, raising questions about the Fermi Paradox and the origin of life.
Evidence has been found that a subduction event, the driver of plate tectonics, occurred exceptionally early in the Earth's formation, contradicting existing models.
Planetary scientists are now directing attention to mantle plumes triggered by Earth's collision with Theia, a Mars-sized object whose impact gave rise to the Moon.
Earth is the only planet with plate tectonics, a process crucial to life as we know it. Without the movement of continents, we would not be here, nor any other life form capable of comprising our planet.
The possibility that plate tectonics is a very rare phenomenon is considered one of the possible explanations for the Fermi Paradox, which questions the lack of evidence of other extraterrestrial civilizations.
The connection between the presence of the Moon and plate tectonics on Earth has been the subject of numerous hypotheses over the years, but until now there has been a lack of concrete evidence to support this theory.
However, 4.3 billion-year-old zircon crystals found in Western Australia may finally provide the missing piece. Zircons, known for their strength and ability to reveal the age of rocks, may have been formed during subduction events.
For more than two decades, some scientists have argued that the chemistry of these ancient zircons suggests the presence of subduction, a process that would not typically occur so early in Earth's history.
A team of researchers recently proposed a model that explains how Theia's impact with Earth 4.51 billion years ago triggered prolonged heating of the core-mantle boundary, creating the conditions for the mantle plumes that led to subduction.
According to the model, about 120 million years after the impact, superheated mantle blobs headed toward the surface, starting the subduction process that shaped the Earth's crust as we know it today.
While it is not yet clear whether modern plate tectonics can be directly linked to the Theia impact, the hypothesis that such a monumental event influenced Earth's tectonic movements raises important questions about the rarity of planets capable of supporting advanced life.
The recycling of crustal material through the mantle, made possible by plate tectonics, may have played a crucial role in moderating extreme temperatures on Earth before life developed, creating conditions favorable to life as we know it.
The study that led to these discoveries was published in open access in the journal Geophysical Research Letters (https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023GL106723), shedding new light on the importance of primordial events in the formation and evolution of our planet.
