Extensive deposits of carbonate sedimentary rocks may be buried several kilometres beneath the surface of Mars, according to a study published online this week in Nature Geoscience. The presence of abundant carbonate minerals could indicate the past existence of a surface environment rich in carbon dioxide.

Carbonate minerals have previously been detected on Mars, but the observations have been sparse and isolated. Joseph Michalski and Paul Niles used satellite data to assess the geology of the Leighton Crater, near the martian Syrtis Major volcano. Their data reveal extensive deposits of carbonate minerals that were exposed by a meteorite impact. The team proposes that these deposits represent ancient sediments that were subsequently buried by volcanic material from Syrtis Major.