Recent geological and hydrological activity on Mars: The Tharsis/Elysium corridor

The paradigm of an ancient warm, wet, and dynamically active Mars, which transitioned into a cold, dry, and internally dead planet,
has persisted up until recently despite published Viking-based geologic maps that indicate geologic and hydrologic activity extending into
the Late Amazonian epoch. This paradigm is shifting to a water-enriched planet, which may still exhibit internal activity, based on a
collection of geologic, hydrologic, topographic, chemical, and elemental evidences obtained by the Viking, Mars Global Surveyor
(MGS), Mars Odyssey (MO), Mars Exploration Rovers (MER), and Mars Express (MEx) missions. The evidence includes:
(1) stratigraphically young rock materials such as pristine lava flows with few, if any, superposed impact craters; (2) tectonic features that
cut stratigraphically young materials; (3) features with possible aqueous origin such as structurally controlled channels that dissect
stratigraphically young materials and anastomosing-patterned slope streaks on hillslopes; (4) spatially varying elemental abundances for
such elements as hydrogen (H) and chlorine (Cl) recorded in rock materials up to 0.33m depth; and (5) regions of elevated atmospheric
methane. This evidence is pronounced in parts of Tharsis, Elysium, and the region that straddles the two volcanic provinces, collectively
referred to here as the Tharsis/Elysium corridor. Based in part on field investigations of Solfatara Crater, Italy, recommended as a
suitable terrestrial analog, the Tharsis/Elysium corridor should be considered a prime target for Mars Reconnaissance Orbiter (MRO) investigations and future science-driven exploration to investigate whether Mars is internally and hydrologically active at the present
time, and whether the persistence of this activity has resulted in biologic activity.