04 October 2013

Explosive supervolcanoes may have once rocked Mars

This image shows digital elevation data overlaid on daytime thermal infrared images of Eden Patera, the type example of an ancient supervolcano on Mars. Red colors are relatively high and purple-gray colors are low. Image released Oct. 2, 2013. (NASA/JPL/GSFC/Arizona State University) 

In a report that appeared in the journal Nature this week, scientists say they have discovered a supervolcano on Mars for the first time. The scientists determined that a vast circular basin on the face of the Red Planet is actually the remains of an ancient supervolcano eruption. To reach this conclusion, the team used images and topograhic data from NASA’s Mars Odyssey, Mars Global Surveyor and Mars Reconnaissance Orbiter spacecraft.

“On Mars, young volcanoes have a very distinctive appearance that allows us to identify them,” stated Joseph R. Michalski, a Senior Scientist at the Planetary Science Institute, who led the study. “The long-standing question has been what ancient volcanoes on Mars look like. Perhaps they look like this one.”

The researchers said a large body of magma loaded with dissolved gas rose through a thin crust to the surface rapidly, like a bottle of soda that has been shaken. This supervolcano would have ejected its contents far and wide, spilling ash and material across vast swaths of the Red Planet.

“This highly explosive type of eruption is a game-changer, spewing many times more ash and other material than typical, younger Martian volcanoes,” said Jacob E. Bleacher of NASA Goddard Space Flight Center, who co-authored the paper. “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.”

When the supervolcano expelled all its material from the eruption, it caused all the ground around it to sink like a balloon deprived of its air.

The supervolcano is located in the Arabia Terra region of Mars, which is a battered terrain loaded with impact craters. When Michalski examined this particularly basin more closely, he noticed that it lacked the raised rim that an impact crater typically has. He was also unable to find a blanket of ejecta, the melted rock that splashes outside the crater when an object hits.

After noting this, Michalski contacted Bleacher, who identified features at Eden Patera that usually indicate volcanic activity. The scientists found that the outside of the basin is ringed by the kinds of faults and valleys that occur when the ground collapses because of activity below the surface. They also found a few more basins nearby that are volcano candidates.

“If just a handful of volcanoes like these were once active, they could have had a major impact on the evolution of Mars,” Bleacher said


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