A new study finds that we may be wrong about the source of the continents, as the Earth’s continents are part of the reason why the Earth is habitable, and what makes it unique among the planets within our solar system, but it is still very much a mystery, and scientists do not know why the surface of the Earth is divided to those important parts.
Those continents were able to stand above sea level, themselves essential to terrestrial life; because the continental crust is lower in iron and more oxidized compared to the crust under the ocean; This means that the continents are less dense and more buoyant, which means they sit higher.
One story suggests that this is caused by the crystallization of the mineral garnet, which was proposed in 2018 and has become a popular explanation for the formation of Earth as we know it.
In this interpretation, the opal crystallizes in magma under continental arc volcanoes, as the oceanic plate moves below the continental plate, and this process removes the unoxidized iron.
cancel that hypothesis
But the new study debunks this hypothesis, as well as providing a better understanding of the continents. The team behind it searched for a way to test this hypothesis about crystallization of agate, by replicating a version of that temperature and pressure in the laboratory.
They did this by using “piston-cylinder presses,” which could apply huge amounts of forces to small samples, as well as using a heating group that heated them at the same time.
In 13 different experiments, the researchers grew garnet samples from molten rock in conditions similar to those found inside Earth’s crust, and then collected garnet samples from around the world. These elements were analyzed until their composition was known, and the researchers knew how much oxidized and unoxidized iron they had.
The researchers then compared the two to X-ray beams that were used to understand their composition. They found that agate does not take in enough non-oxidized iron to account for the makeup on earth.
These results make the agate crystal model a very unlikely explanation for why magma from continental volcanoes oxidizes and iron depletes, and it is likely that conditions in the Earth’s mantle below the continental crust create these oxidizing conditions.
This means that one of the leading theories can now be dismissed. But it’s still not known exactly what’s going on, and the researchers hope to work on further research to understand what’s going on in this mysterious process.
