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2 December (UPI) – Earth’s first continents were fragile and prone to destruction, according to a new study published Wednesday in the journal Nature.
The Earth formed about 4.5 billion years ago, but the planet’s childhood – its first 1.5 billion years – and the processes that shaped its continental characteristics are poorly understood.
“This was the moment of the formation of the first continents, the emergence of the earth, the development of the primeval atmosphere and the appearance of primordial life, all results that are the result of the dynamics of the interior of our planet”, the lead author Fabio Capitanio said in a press release.
For the new study, Capitanio and his colleagues created computer models that simulate the conditions of the early Earth.
“We show that the release of internal primordial heat, three or four times that of today, caused a great melting in the surface mantle, which was then extruded as magma … onto the Earth’s surface,” said Capitanio, a researcher at Monash in Australia.
According to the models, the pieces of mantle left by this process formed the keels of the planet’s first continents. The morphologies, however, were dehydrated and rigid.
Simulations suggest that the first continents remained weak for billions of years and were prone to destruction. In the beginning, the landforms of the Earth were easy to dissolve, making them more malleable, allowing them to differentiate themselves more and more.
Over time, this process produced larger and more rigid pieces of mantle, forming what would become the cores of modern continents.
Today, these nuclei take the form of cratons, the large, stable pieces of mantle and crust found within Earth’s continents.
The process of the formation of the first continents was essential for the evolution of the geochemistry of the Earth and, ultimately, of the biochemistry of the planet.
“The emergence of these first rigid continents has resulted in their deterioration and erosion, changing the composition of the atmosphere and providing nutrients to the ocean that sows the development of life,” said Capitanio.
The new research also explains why so little of the Earth’s primordial crust remains. The destruction and incorporation of the Earth’s first continental crust into the mantle helped strengthen the keel-like mantle pieces that came to form the cratons.
According to Capitanio and his colleagues, these cratons house the earliest evidence of life on Earth, but they make up only a tiny fraction of the Earth’s surface.
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