May 28, 2014
Mars Volcano Could Have Created Habitable Lakes Of Liquid Water
redOrbit Staff & Wire Reports - Your Universe Online
As part of the ongoing search for potentially habitable regions of Mars, geologists from Brown University have pinpointed a volcano that was once encased in glacial ice which could have created large lakes of liquid water.
Arsia Mons is one of the largest mountains in the solar system, and the third tallest volcano on Mars, the study authors said in a statement. By analyzing the landforms surrounding the mountain, they found that eruptions along its northwest flank occurred approximately 210 million years ago.
The volcano was covered by a glacier at the time, and the heat from the eruptions would have melted enough ice to form bodies of water known as englacial lakes. Those ice-covered lakes would have been home to hundreds of cubic kilometers of meltwater, based on the calculations of lead investigator and geological sciences graduate student Kat Scanlon and her colleagues.
“This is interesting because it’s a way to get a lot of liquid water very recently on Mars,” Scanlon said. “If signs of past life are ever found at those older sites, then Arsia Mons would be the next place I would want to go.”
While it was over 200 million years ago, the researchers noted that the Arsia Mons site is far more recent than other habitable environments discovered by Curiosity and other Mars rovers, which are all believed to be at least 2.5 billion years old. That makes the Arsia Mons site a good candidate for possible future exploration.
There has been speculation in the scientific community for roughly four decades that the northwestern flank of the volcano might have been covered by glacial ice at one point. In 2003, Brown University geologist Jim Head and Boston University professor David Marchant demonstrated that the terrain around Arsia Mons closely resembles landforms left by receding glaciers in the Dry Valleys of Antarctica.
“Parallel ridges toward the bottom of the mountain appear to be drop moraines – piles of rubble deposited at the edges of a receding glacier. An assemblage of small hills in the region also appears to be debris left behind by slowly flowing glacial ice,” the university said. “The glacier idea got another boost with recently developed climate models for Mars that take into account changes in the planet’s axis tilt.”
Those models suggest that ice currently found at the planet’s poles would have migrated towards the equator during periods of increased tilt. That means that Arsia Mons and the other large mid-latitude mountains found on Mars (Ascraeus Mons and Pavonis Mons) would have been likely locations for glaciations about 210 million years ago.
Scanlon joined forces with Head, Marchant and Lionel Wilson from the Lancaster Environmental Centre to search data from NASA’s Mars Reconnaissance Orbiter for evidence that hot volcanic lava could have flowed in the region around the same time that the glaciers were present.
The study authors found pillow lava formations similar to those caused by an eruption at the bottom of an ocean, as well as ridges and mounds like those that form when glacial ice constrains a lava flow here on Earth. The pressure of the ice sheet constrains the lava flow, and the erupting lava is cooled by the glacial meltwater, forming fragments of volcanic glass. The end result is mounds and ridges that have flat tops and steep sides.
“The analysis also turned up evidence of a river formed in a jökulhlaup, a massive flood that occurs when water trapped in a glacier breaks free,” the university said. Based on the sizes of the formations, Scanlon estimated the amount of lava that would have interacted with the glacier. She then used basic thermodynamics to calculate the amount of meltwater that would have been produced by the lava.
Two of the deposits would have created lakes that each contained approximately 40 cubic kilometers of water, while the third would have created roughly 20 cubic kilometers of water. Even in a frigid environment like Mars, that much ice-covered water would have stayed a liquid for a substantial amount of time, Scanlon said.
Her calculations suggest that the lakes could have persisted for as much as a few thousand years – potentially long enough for the lakes to be colonized by microbial life forms, provided they ever existed on the Red Planet. Furthermore, Head suggests that some glacial ice could still remain at the Arsia Mons site.
“Remnant craters and ridges strongly suggest that some of the glacial ice remains buried below rock and soil debris,” he said. “That’s interesting from a scientific point of view because it likely preserves in tiny bubbles a record of the atmosphere of Mars hundreds of millions of years ago. But an existing ice deposit might also be an exploitable water source for future human exploration.”
Image 2 (below): Braided fluvial channels (inset) emerge from the edge of glacial deposits roughly 210 million years old on the martian volcano Arsia Mons, nearly twice as high as Mount Everest. (Colors indicate elevation.) Credit: NASA/Goddard Space Flight Center/Arizona State University/Brown University