Geology with Mars Express

Mars Express include three instruments that may integrate to provide an unprecedented view of Mars: HRSC, OMEGA, and MARSIS. The camera is a key instrument to understand the 3D nature of geological features, units, and sedimentary bodies. In most cases, the three dimensional capability of the stereo camera allows the geologist to view large outcrops with an Earth-like approach. Exposures and geological features can be observed from different locations and with different angle of views. The same analytical techniques and concepts used for terrestrial large outcrops and seismic lines can be used to analyse HRSC data. Two examples give the sense of this virtual field geologist approach: the evaporite facies and the fluvio-deltaic deposits. The geology of the evaporites seems to be on Mars as complicate as on Earth because these lithofacies have been detected in several locations and in different settings. In some cases, evaporites belong to sedimentary units that formed sebkhas, whereas, in other instances, they seem to be simple veneers over pre-existing surfaces. Fluvio-deltaic environments are widespread over Mars and their analysis may provide important hints of the plaeohydrological and paleoclimatic evolution of the Planets. The detailed 3D models of the fluvio-deltaic sedimentary bodies allow the reconstruction of the evolution of the lacustrine environments through the reconstruction of the deltaic dynamics and of the stratigraphic sequences. 3D models, mineralogical maps and high-resolution images concur to create virtual field outcrops and put the geologists in virtual field areas