ASU researcher Steven W. Ruff, is co-author of a new report published in Science, that concludes Mars had a warmer, wetter climate during its first billion years resulting from a denser CO2-rich atmosphere.
"Such an atmosphere should have led to the formation of outcrops rich in carbonate minerals, for which evidence has been sparse. Using the Mars Exploration Rover Spirit, we have now identified outcrops rich in magnesium-iron carbonate (16 to 34 weight percent) in the Columbia Hills of Gusev crater. Its composition approximates the average composition of the carbonate globules in martian meteorite ALH 84001. The Gusev carbonate probably precipitated from carbonate-bearing solutions under hydrothermal conditions at near-neutral pH in association with volcanic activity..."
[right, "false-color Pancam image (Sol689_P2571) looking downslope over Algonquin and Comanche outcrops. Strike and dip are indicated by black lines and black arrow. The location of the MB and APXS workspace is indicated by the white circle. The inset locates from high to low elevation the olivine-rich outcrops Larry’s Bench (LB), Seminole (S), Algonquin (A), and Comanche (C) on Spirit’s traverse across Haskin Ridge down the southeast slope of Husband Hill. The distance between Algonquin and Comanche outcrops is ~85 m." Credits: NASA/JPL/Pancam and NASA/UA/HiRISE]