Volcanic eruptions likely led to Medusae Fossae, study reports

New evidence shows that volcanic eruptions likely caused the Medusae Fossae Formation on Mars.
By Joseph Scalise | Oct 01, 2018
Astronomers may have finally discovered what mechanisms formed Mars' mysterious Medusae Fossae Formation, according to recent researchpublished in the Journal of Geophysical Research.

"This is a massive deposit, not only on a Martian scale, but also in terms of the solar system, because we do not know of any other deposit that is like this," said lead author Lujendra Ojha, a planetary scientist at Johns Hopkins, according to Newsweek

The large formation -- which stretches out roughly 3,100 miles across Mars' equator -- has perplexed scientists for decades. That is because, while the strange rock appears smooth from above, it is filled with many grooves, hills, and valleys.

While researchers know Medusae Fossae is made of sedimentary rock, they have no idea which natural mechanisms created it. Wind and water are likely causes, but so are ice and volcanic activity.

To help answer that question, astronomers from John Hopkins University used data from various Mars orbiters to study the formation. That revealed the rock inside of it is porous, roughly a third less dense than the rest of the planet's crust. As a result, it is likely it came from volcanic eruptions that took place some 3 billion years ago.

That explains the hills and valleys because, while most of the light rock is still intact, roughly half of it eroded away with time.

Such information is important because it one day help scientists better understand Mars' geology and shed light on how it may have once supported life.

Past volcanic eruptions would have greatly altered the planet, emitting enough gas to warm it and enough water to completely cover the surface.

In addition, the new findings also suggest the Martian interior is more complex than originally thought. That is because the planet's interior would have needed large amounts of volatile gases to create a deposit as big as Medusae Fossae.

"If you were to distribute the Medusae Fossae globally, it would make a 9.7-meter (32-foot) thick layer," added Ojha, in a statement. "Given the sheer magnitude of this deposit, it really is incredible because it implies that the magma was not only rich in volatiles and also that it had to be volatile-rich for long periods of time."

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