Iapygia Quadrangle - Carbonates

Carbonates

Carbonates (calcium or iron carbonates) were discovered in a crater on the rim of Huygens Crater. The impact on the rim exposed material that had been dug up from the impact that created Huygens. These minerals represent evidence that Mars once was had a thicker carbon dioxide atmosphere with abundant moisture. These kind of carbonates only form when there is a lot of water. They were found with the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on the Mars Reconnaissance Orbiter. Earlier, the instrument had detected clay minerals. The carbonates were found near the clay minerals. Both of these minerals form in wet environments. It is supposed that billions of years age Mars was much warmer and wetter. At that time, carbonates would have formed from water and the carbon dioxide-rich amosphere. Later the deposits of carbonate would have been buried. The double impact has now exposed the minerals. Earth has vast carbonate deposits in the form of limestone.

• Huygens Crater with circle showing place where carbonate was discovered. This deposit may represent a time when Mars had abundant liquid water on its surface. Scale bar is 259 km long.