NASA’s Mars Reconnaissance Orbiter captured this image of sand dunes on Mars.
Sand dunes cover much of this terrain, which has large boulders lying on flat areas between the dunes. It is late winter in the southern hemisphere of Mars, and these dunes are just getting enough sunlight to start defrosting their seasonal cover of carbon dioxide. Spots form where pressurized carbon dioxide gas escapes to the surface.
This image was taken on March 27, 2016, at 15:31 local Mars time by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter.
The carbon-di-oxide of Mars has not made any carbonates as solid material due to lack of planet lying very cold. Hence carbon di oxided ice on the equitorial and non-polar regions of the planet getting sun shine melts these carbon di oxide ice to vaporize which forms these sand dunes spotted helped by Martian winds. Thank You.