Formation of Recent Martian Debris Flows by Melting of Near-Surface Ground Ice at High Obliquity
F. Costard,1
F. Forget,2*
N. Mangold,1
J. P. Peulvast1
The observation of small gullies associated with recent
surface runoff on Mars has renewed the question of liquid water
stability at the surface of Mars. The gullies could be formed by
groundwater seepage from underground aquifers; however, observations of
gullies originating from isolated peaks and dune crests question this scenario. We show that these landforms may result from the melting of
water ice in the top few meters of the martian subsurface at high
obliquity. Our conclusions are based on the analogy between the martian
gullies and terrestrial debris flows observed in Greenland and
numerical simulations that show that above-freezing temperatures can
occur at high obliquities in the near surface of Mars, and that such
temperatures are only predicted at latitudes and for slope orientations
corresponding to where the gullies have been observed on Mars.
1 UMR8616, Centre National de la Recherche
Scientifique (CNRS), OrsayTerre, Équipe de Géomorphologie
Planétaire, Université Paris-Sud, 91405, Orsay Cedex,
France.
2 Laboratoire de Météorologie
Dynamique, CNRS, Université Paris 6, Boîte Postal 99, 75252 Paris 05, France.
*
To whom correspondence should be addressed. E-mail:
forget{at}lmd.jussieu.fr
