(ORDO NEWS) — Florida State University scientists have uncovered the cooling time of an ancient magma ocean that covered the entire surface of the young Earth and went thousands of kilometers deep into its bowels.
The rate of cooling of magma influenced the formation of the geological layers of the planet and their chemical composition.
Geologists have conducted molecular dynamics simulations of basaltic melt in the Earth’s interior, where pressure and temperature reach extreme values ​​- up to 136 gigapascals and 2200-4000 kelvins, respectively.
Basaltic melts are formed as a result of partial melting of the mantle and form a large part of the material of the earth’s crust.
However, samples of lava erupted in areas of underwater ridges and volcanic islands indicate that molten rocks resembling basalt with an unusual chemical composition are present in the lower part of the Earth’s mantle.
The presence of basalt melts in the Earth’s interior can be explained by the existence of an ancient magma ocean with low viscosity.
Low-viscosity magma cools rapidly, forming dense crystals that sink to the Earth’s core, changing the chemical composition of the geological layers.
However, for a long time it remained a mystery what viscosity the magma ocean should have had if it really existed, and how it changed under extreme pressure conditions.
Previous models have shown that the cooling time of the magma ocean varies greatly from a few to hundreds of millions of years.
For example, with a viscosity of 100 pascal seconds, it would cool down for 100-200 million years.
However, the results of the new study indicate that the viscosity could be several orders of magnitude lower and be around 0.01-0.03 pascal-seconds.
In this case, the magma ocean could cool down in less than a few million years.
The less viscous magma contributed to fractional crystallization the rapid separation of crystals suspended in it creating a heterogeneous composition.
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