Clay Studies Alter View of Early Mars Environment

Jul 18, 2007
Clay Studies Alter View ...

A study of the thermodynamics of clays found on Mars suggests that little carbon dioxide could have been present during their formation, which contradicts a popular theory of the early Martian atmosphere and will send researchers looking for other explanations for clay formation.

Vincent Chevrier of the University of Arkansas and François Poulet and Jean-Pierre Bibring of the Université Paris-Sud in Orsay, France, reported their findings in the journal Nature.

Gullies, valleys and clay formations found on Mars seem to point to a wet past for the Red Planet. Almost all clays formed on earth do so in the presence of water or under extremely humid conditions. These clay remnants of ancient Mars had previously led scientists to hypothesize that the earliest era on the planet, the Noachian period, had a carbon-dioxide-rich atmosphere that created a warm, wet surface with liquid water -- ideal for creating clays.

Chevrier used thermodynamic calculations to examine possible historic conditions on the planet. These calculations look at the equilibrium conditions of the clay deposits on Mars with respect to different relevant other mineral phases -- carbonates, sulfates, iron oxides -- to extrapolate the surface environment at the time of their formation. He made the assumption that the clays would form on the surface of Mars in the presence of liquid water as they do on Earth.

In a carbon-dioxide-rich environment, clay formation would be accompanied by carbonate formation, but current studies of Mars have found no such compounds. Chevrier's calculations show that, given current conditions, the carbon dioxide pressure would have been low in the Noachian atmosphere.

"If you had a thick atmosphere of carbon dioxide, you should have abundant carbonates," Chevrier said. "So far no one has seen even a grain of carbonate."

Despite this evidence that carbon dioxide did not provide a warm, wet atmosphere, it is possible that other greenhouse gases, such as methane, helped create the ancient conditions that shaped modern-day Mars. It also is possible that impacts generated heat and energy that could have warmed the Mars surface, creating liquid water. However, both of these hypotheses present their own enigmas: If methane was present, where did it go? And how do you relate impacts to the formation of clays? On Mars, thousands of square kilometers are covered by clay deposits up to 100 meters thick - not the hallmark of a single impact event.

Another possibility is that some of these chemicals - the carbonates and the methane - may be present deep below the surface of Mars. To address the question of the underground presence of these materials will require a Mars rover with a probe. Until then, the history of the early Martian atmosphere remains an enigma.

"Thermodynamics can give you the conditions, but not the process," Chevrier said.

Source: University of Arkansas

Explore further: Bright points in Sun's atmosphere mark patterns deep in its interior

add to favorites email to friend print save as pdf

Related Stories

Curiosity Mars rover finds sandstone variations

Mar 25, 2014

(Phys.org) —Variations in the stuff that cements grains together in sandstone have shaped the landscape surrounding NASA's Curiosity Mars rover and could be a study topic at the mission's next science waypoint.

Happy 10th anniversary Opportunity

Jan 23, 2014

Ten years ago, on Jan. 24, 2004, the Opportunity rover landed on a flat plain in the southern highlands of the planet Mars and rolled into an impact crater scientists didn't even know existed. The mission ...

Recommended for you

Astronauts to reveal sobering data on asteroid impacts

16 hours ago

This Earth Day, Tuesday, April 22, three former NASA astronauts will present new evidence that our planet has experienced many more large-scale asteroid impacts over the past decade than previously thought… ...

Rosetta instrument commissioning continues

16 hours ago

We're now in week four of six dedicated to commissioning Rosetta's science instruments after the long hibernation period, with the majority now having completed at least a first initial switch on.

Astronaut salary

17 hours ago

Talk about a high-flying career! Being a government astronaut means you have the chance to go into space and take part in some neat projects—such as going on spacewalks, moving robotic arms and doing science ...

Red moon at night; stargazer's delight

Apr 16, 2014

Monday night's lunar eclipse proved just as delightful as expected to those able to view it. On the East Coast, cloudy skies may have gotten in the way, but at the National Science Foundation's National Optical ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

out7x
1 / 5 (1) Dec 06, 2007
The CO2 atmosphere would have escaped due to insufficient gravity. Carbonates form in shallow seas. Clay formation is from weathering. These are two separate processes.

More news stories

Cosmologists weigh cosmic filaments and voids

(Phys.org) —Cosmologists have established that much of the stuff of the universe is made of dark matter, a mysterious, invisible substance that can't be directly detected but which exerts a gravitational ...

Hubble image: A cross-section of the universe

An image of a galaxy cluster taken by the NASA/ESA Hubble Space Telescope gives a remarkable cross-section of the Universe, showing objects at different distances and stages in cosmic history. They range ...

Scientists tether lionfish to Cayman reefs

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

White House updating online privacy policy

A new Obama administration privacy policy out Friday explains how the government will gather the user data of online visitors to WhiteHouse.gov, mobile apps and social media sites. It also clarifies that ...