Mars crater may actually be ancient supervolcano

Seen above, for the basin and surrounding area, higher elevations (reds and yellows) and lower elevations (blues and grays) are indicated. Credit: NASA/JPL/GSFC

A research project led by Joseph R. Michalski, Senior Scientist at the Planetary Science Institute, has identified what could be a supervolcano on Mars – the first discovery of its kind.

In a paper published Oct. 3 in the journal Nature, Michalski and co-author Jacob E. Bleacher of NASA Goddard Space Flight Center describe a new type of volcanic construction on Mars that until now has gone unrecognized.

The volcano in question, a vast circular basin on the face of the Red Planet, previously had been classified as an impact crater.

Researchers now suggest the basin is actually the remains of an ancient supervolcano eruption.

Their assessment is based on images and topographic data from NASA's Mars Odyssey, Mars Global Surveyor and Mars Reconnaissance Orbiter (MRO) spacecraft, as well as the European Space Agency's Mars Express orbiter.

In the Nature paper Michalski and Bleacher lay out their case that the basin, recently named Eden Patera, is a volcanic caldera. Because a caldera is a depression, it can look like a crater formed by an impact, rather than a volcano.

"On Mars, young volcanoes have a very distinctive appearance that allows us to identify them," Michalski said. "The long-standing question has been what ancient volcanoes on Mars look like. Perhaps they look like this one."

Above, the dark color indicates younger material draped across the Eden Patera depression. 

Credit: ESA

The researchers also suggest a large body of magma loaded with dissolved gas (similar to the carbonation in soda) rose through thin crust to the surface quickly.

Like a bottle of soda that has been shaken, this supervolcano would have blown its contents far and wide if the top came off suddenly.

"This highly explosive type of eruption is a game-changer, spewing many times more ash and other material than typical, younger Martian volcanoes," Bleacher said.

"During these types of eruptions on Earth, the debris may spread so far through the atmosphere and remain so long that it alters the global temperature for years."

After the material is expelled from the eruption, the depression that is left can collapse even further, causing the ground around it to sink.

Eruptions like these happened in ages past at what is now Yellowstone National Park in the western United States, Lake Toba in Indonesia and Lake Taupo in New Zealand.

More information: www.nature.com/nature/journal/v502/n7469/full/nature12482.html