Giant impact theory of plate tectonics

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The giant impact theory of plate tectonics suggests that the formation of continents and the initiation of plate tectonics on Earth could be the result of massive meteorite impacts that occurred during the first billion years of the planet's history . The theory posits that these impacts generated enormous amounts of energy, causing the outer shell of the Earth, or the lithosphere, to melt and form oceanic plates. The resulting decrease in pressure on the underlying mantle would have caused it to melt as well, creating an oceanic plateau, which is a large mass of thick basaltic crust similar to that beneath present-day Hawaii or Iceland . If the oceanic plateau is large enough, it can get hot enough at its base that it also melts, producing the kind of granitic rock that forms buoyant continental crust. This process is known as crustal differentiation, and it is thought to be responsible for the formation of the continents . Evidence for the giant impact theory of plate tectonics comes from the study of ancient minerals, such as zircon crystals, found in rocks from the Pilbara Craton in Western Australia. The isotopic composition of these crystals suggests that they were formed in a handful of distinct periods, rather than continuously over time. Furthermore, the ages of these crystals correspond to the ages of spherule beds, which are deposits of droplets of material "splashed out" by meteorite impacts, suggesting that the zircons and the spherule beds were formed by the same events . The giant impact theory of plate tectonics is not the only explanation for the formation of continents and the initiation of plate tectonics on Earth. Another theory suggests that the remains of a Mars-sized planet, dubbed Theia, that collided with the nascent Earth could have also triggered the onset of subduction, a hallmark of modern plate tectonics . However, it is still too early to say whether this is, in fact, what happened, and the search for other Earth-like worlds with plate tectonics could aid in the understanding of the processes that shaped our own planet. In summary, the giant impact theory of plate tectonics proposes that massive meteorite impacts during the first billion years of Earth's history led to the formation of oceanic plates and the initiation of plate tectonics. The resulting oceanic plateaus could have evolved to form the continents through crustal differentiation. While this theory is supported by evidence from the study of ancient minerals, it is not the only explanation for the formation of continents and the initiation of plate tectonics on Earth.
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