It made a mess. Scientists have figured out how Earth’s continents actually formed

Earth’s continents are huge masses of the earth’s crust separating its oceans and are extremely important to the planet. However, until now, scientists have been unable to come to a single denominator as to when they will understand what actually caused these massive landmasses that make Earth unique on the solar planet and play an important role in the formation of life on the planet, Space writes. .

For a long time, researchers believed that garnet crystallization in magma under volcanoes was responsible for removing iron from the earth’s crust. Scientists believed that this was what allowed the crust to survive in Earth’s oceans. However, a new study by scientists casts doubt on this theory and forces geologists and planetary scientists to reconsider the process of formation of Earth’s continents.

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The earth’s crust is the outer crust of the planet and is conventionally divided into two categories:

• older, thicker continental crust;
• younger, denser oceanic crust.

The researchers note that new continental crust begins to form when the building blocks are transferred from continental arc volcanoes to the planet’s surface. They are known to be found in three parts of the world where oceanic plates subduct under continental plates. These areas are called subduction zones.

Note that dry continental crusts differ from deep sea oceans in the absence of iron in the continental crust. In simple terms, due to a lack of iron, continental crusts become buoyant and rise above sea level, forming the landmasses that make life possible on Earth.

Previously, researchers had suggested that the low iron content in the earth’s crust was the result of garnet crystallization in magma under continental arc volcanoes. Basically, this process removes unoxidized iron from Earth’s plates and consumes it from the molten magma, making it more oxidized as the continental crust forms.

In a new study, a team led by Cornell University assistant professor Megan Holycross and Smithsonian National Museum of Natural History geologist Elizabeth Cottrell set out to test the theory. It seems that for the first time in the last 5 years, since 2018, when it was first mentioned, scientists have managed to disprove it.

To test this theory, the scientists recreated the enormous pressure and heat characteristic of the area under continental arc volcanoes. To do this, they used piston-cylinder presses at the Smithsonian’s High Pressure Laboratory and at Cornell University. These pistons are no bigger than a refrigerator and are made of steel and tungsten carbide, but they can exert enormous pressure on very small rock samples when heating them in a cylindrical furnace.

Note that the temperature in the furnace ranges from 950 to 1230 degrees Celsius, and the pressure created is 15-30 thousand times higher than atmospheric pressure. Next, Cottrell and colleagues performed a series of 13 lab tests in which they were able to grow garnet samples from molten rock under pressure and temperature that mimicked conditions inside magma chambers deep in the Earth’s crust.

Next, the scientists analyzed lab-grown samples using X-ray absorption spectroscopy, which can recognize the composition of objects based on how they absorb X-rays. The results of the study show that these pomegranates do not absorb enough oxidized iron. In simple terms, they cannot be fully responsible for the levels of iron depletion and oxidation seen in continental-forming magmas. As a result, scientists came to the conclusion that what is considered one of the most plausible theories is actually unlikely.

At the same time, the researchers note that so far they have only managed to refute the popular theory, but the results of their work, unfortunately, do not provide alternative hypotheses that could explain the formation of the continental crust.

Previously Focus He wrote about how a single meteorite changed the chemical composition of the Earth’s crust.