The primordial Earth was a hellish place: hot, turbulent, fast-spinning, and bombarded by extraterrestrial debris, including a Mars-sized object whose impact created the moon. The same impact also turned the entire surface of the newly formed Earth into a sea of molten magma.
Nationalgeographic.co.id—Early in Earth’s formation, oceans of magma covered the planet’s surface and extended thousands of kilometers deep into its core. The rate at which the “magma oceans” cool affects the formation of the different layers within the Earth and the chemical makeup of those layers.
Previous studies had estimated that it would take hundreds of millions of years for that sea of magma to harden, but new research from Florida State University narrows this huge uncertainty to less than a few million years.
The research results have been published in the journal Nature Communications dengan judul “Insights into magma ocean dynamics from the transport properties of basaltic melt.”
“This magma ocean has been an important part of Earth’s history, and this research helps us answer some fundamental questions about this planet,” said Mainak Mookherjee, a professor of geology in the Department of Earth, Ocean and Atmospheric Sciences.
When magma cools, it forms crystals. Where those crystals end up depends on how viscous the magma is and the relative density of the crystals.
The denser crystals tend to sink and thus change the composition of the remaining magma. The degree of freezing of magma depends on how viscous the magma is.
Magma that is less viscous will result in faster cooling, while magma oceans with a thicker consistency will take longer to cool.
An illustration of Earth as it existed during part of its formation billions of years ago, when oceans of magma covered the planet’s surface and stretched thousands of kilometers deep into its core. A typical cell from a simulation performed by FSU researchers with the relative positions of the atoms is shown on the left.
Like this study, previous studies have used basic principles of physics and chemistry to simulate high pressures and temperatures in the Earth’s interior. Scientists also use experiments to simulate these extreme conditions. But these experiments are limited to lower pressures, which exist at shallower depths within the Earth.
They do not fully capture the scenario that existed in the early history of the planet. Where magma oceans extend to depths where the pressure is probably three times higher than what experiments can reproduce.
To overcome these limitations, Mookherjee and collaborators ran their simulations for up to six months in high-performance computing facilities at FSU as well as at the National Science Foundation’s computing facilities. This removes many of the statistical uncertainties in previous work.
“Earth is a large planet, so at depth, the pressure tends to be very high,” said Suraj Bajgain, a former postdoctoral researcher at FSU who is now a visiting assistant professor at Lake Superior State University. “Even if we know the viscosity of magma at the surface, it doesn’t tell us the thickness hundreds of kilometers below. Finding it is very challenging.”
