[meteorite-list] Mars Crater May Actually Be Ancient Supervolcano

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 2 Oct 2013 11:13:40 -0700 (PDT)
Message-ID: <201310021813.r92IDe0r029714_at_zagami.jpl.nasa.gov>

Content-Transfer-Encoding: quoted-printable


Alan Fischer
Public Information Officer
Planetary Science Institute
fischer at psi.edu

Mars Crater May Actually Be Ancient Supervolcano

Oct. 2, 2013, Tucson, Ariz. -- 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
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."

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

"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.

Volcanoes previously had not been identified in the Arabia Terra region of
Mars, where Eden Patera is located. The battered, heavily eroded terrain is
known for its impact craters. But as Michalski examined this particular
basin more closely, he noticed it lacked the typical raised rim of an
impact crater. He also could not find a nearby blanket of ejecta, the
melted rock that splashes outside the crater when an object hits.

The absence of such key features caused Michalski to suspect volcanic
activity. He contacted Bleacher, a volcano specialist, who identified
features at Eden Patera that usually indicate volcanism, such as a series
of rock ledges that looked like the "bathtub rings" left after a lava lake
slowly drains. In addition, 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. The existence of these and other volcanic
features in one place convinced the scientists Eden Patera should be

The team found a few more basins that are candidate volcanoes nearby,
suggesting conditions in Arabia Terra might have been favorable for
supervolcanoes. It is also possible massive eruptions here could have been
responsible for volcanic deposits elsewhere on Mars that have never been
linked to a known volcano.

"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.

Visit http://www.psi.edu/news/marssupervolcano.html for images of Eden
Patera basin on Mars.

Project funding was provided by the NASA Mars Data Analysis program.

Joseph R. Michalski
Senior Scientist
+44 74 3261 9949
michalski at psi.edu

Mark V. Sykes
sykes at psi.edu
Received on Wed 02 Oct 2013 02:13:40 PM PDT

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