Today the Earth is made up of seven continents, which make up less than 30 percent of the planet’s landmass, while 70 percent is water. The evolution of continents is the result of plate tectonics and crustal movements over millions of years, giving the planet its current landscape and geography.
However, a new study suggests that it all started with an explosion, providing the strongest evidence yet that Earth’s continents formed as a result of the impact of a giant meteorite. This effect was prevalent during the first billions of our planet’s approximately 4.5 billion year history. The research confirms long-standing speculation that continents began to form around the site of the meteorite strike.
The study, published in the journal Nature, says that Earth is the only planet to have continents, although it is not clear how they formed and evolved. “The giant impact provided a mechanism for the breaking up of the crust and changes in hydrothermal temperature over a long period of time by interacting with the vast oceans globally,” the paper said.
it all started with an explosion
The researchers analyzed tiny crystals of the mineral zircon in rock from the Pilbara Craton in Western Australia. The region contains the best-preserved remains of ancient crust on Earth and evidence of ancient meteorite strikes on the planet. The team, led by researchers from Curtin University, studied the oxygen isotope composition in these zircon crystals.
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Zircon is the oldest mineral on the planet, being about 4.4 billion years old and sometimes containing traces of uranium. They found a top-down process that begins with the melting of rock near the surface and continues at depths consistent with the geological impact of a giant meteorite impact.
“Our research provides the first strong evidence that the process that eventually formed the continents was triggered by the impact of a giant meteorite, which was responsible for the extinction of the dinosaurs, but occurred billions of years ago,” said Dr. Tim Johnson of the Curtin School of Earth and Planetary Sciences said in a statement.
Why do we need to know?
Researchers say understanding the formation and continued evolution of Earth’s continents is important because this soil mass hosts most of Earth’s biomass, all of humanity, and nearly all of the planet’s important mineral deposits. Mineral deposits are the result of a process known as crustal differentiation, which begins with the formation of an initial clay mass.
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“Equally important, the continent has essential minerals such as lithium, lead and nickel, which are essential commodities for the emergence of green technologies necessary to meet our commitments to climate change mitigation,” Dr Johnson said.
The researchers also revealed that data from other regions of ancient continental crust showed a pattern similar to that identified in Western Australia.
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