The researchers explained that the Earth's mantle is a thick layer of silicate rocks between the Earth's crust and the
But the work carried out by the WashingtonLouis University suggests that the deep part of the ancient mantle closest to the Earth's core was significantly drier than the part of the mantle closest to the surface of the young planet.
After analyzing the data on the isotopes of inertgases, Rita Parai determined that the water concentration in the deep part of the mantle was 4–250 times lower compared to the water concentration in the upper part of the mantle. The resulting viscosity contrast may have prevented mixing within the mantle, helping to explain some of the long-standing mysteries of Earth's formation and evolution.
“The viscosity contrast may explain why impacts,that caused the formation of oceans of magma in the mantle, did not lead to the homogenization of the growing planet, notes Parai. "This process may also explain why the mantle has undergone less reworking through partial melting throughout Earth's history."
This study casts doubt on the theory ofthat the Earth's mantle was homogeneous from the very beginning. When the solar system formed 4.5 billion years ago, volatiles such as water, carbon, nitrogen and inert gases entered the Earth, but Parai's study suggests that the material that formed earlier was a drier type of rock than that formed later.
She discovered that isotopes of mantle helium,neo and xenon indicate that at the end of the formation period, the mantle had a low concentration of volatile substances compared to the upper mantle. The upper mantle could have received a larger contribution to the mass from materials rich in volatiles.
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