Paleolakes, paleofloods, and depressions in Aurorae and Ophir plana, Mars: Connectivity of surface and subsurface hydrological systems

Goro Komatsu , Gaetano Di Achille , Ciprian Popa , Stefano Di Lorenzo , Angelo Pio Rossi , Jose Alexis Palmero Rodriguez

The plains of Aurorae and Ophir in the equatorial region of Mars display extensive geomorphic evidence indicative of paleo-hydrological processes linking surface and subsurface. Elaver Vallis in Aurorae Planum south of Ganges Chasma is an outflow channel system >180 km long, and here inferred to have formed by cataclysmic spillover flooding from a paleolake(s) contained within the Morella crater basin. Ganges Cavus is an enormous 5-km-deep depression of probable collapse origin located within the Morella basin. The fluid responsible for the infilling of the Morella basin may have emerged at least partially through Ganges Cavus or its incipient depression. The fluid may have been supplied also from small-scale springs within the basin. It is reasonable to assume that water, sometimes sediment-laden and/or mixed with gases, was the responsible fluid for these phenomena. Similar paleo-hydrological processes are inferred also in Ophir Planum. Water emergence may have occurred as consequences of ground ice melting or breaching of cryosphere to release water from the underlying hydrosphere. Dike intrusion is considered to be an important cause of formation for the cavi and smaller depressions in Aurorae and Ophir plana, explaining also melting of ground ice or breaching of cryosphere. Alternatively, the depressions and crater basins may have been filled by regional groundwater table rising during the period(s) when cryosphere was absent or considerably thin. In both cases, the large quantities of water necessary for explaining the paleo-hydrological processes in Aurorae and Ophir plana may have been derived through crustal migration from the crust of higher plains in western Ophir Planum where water existed in confined aquifers or was produced by melting of ground ice due to magmatic heating or climatic shift, or from a paleolake in Candor Chasma further west.

Mots clés: Mars; Geological processes; Mineralogy

Goro Komatsu, Gaetano Di Achille, Ciprian Popa, Stefano Di Lorenzo, Angelo Pio Rossi, et al.. Paleolakes, paleofloods, and depressions in Aurorae and Ophir plana, Mars: Connectivity of surface and subsurface hydrological systems. Icarus, 2009, 201 (2), pp.474. ⟨10.1016/j.icarus.2009.01.010⟩. ⟨hal-00533498⟩