DPS 2001 meeting, November 2001
Session 48. Mars Surface
Oral, Chairs: N. Barlow, J. Bell III, Friday, November 30, 2001, 4:30-6:40pm, Regency E

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[48.13] Formation of recent gullies and debris-flows on Mars by the melting of near-surface ground ice at high obliquity

F. Forget (LMD, Paris), F. Costard, N. Mangold, J.-P. Peulvast (OrsayTerre, Orsay)

The observation of small gullies associated with recent surface run-off on Mars by Mars Global Surveyor has renewed the question of liquid water stability at the surface of Mars. In their initial analyses, Malin and Edgett [1] suggested that the gullies could be formed by groundwater seepage from underground aquifers. However, observations of gullies originating from the top of peaks question this scenario. We show here that these landforms are more likely to result from the melting of liquid water in the first meter of the Martian subsurface at high obliquity. On the one hand, this is suggested by the analogy between the martian gullies and terrestrial debris flows observed in Greenland which are known to result from the thawing of near-surface ground when above-freezing temperatures are reached. On the other hand, numerical simulations 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 exactly to where the gullies have been observed on Mars.

[1] Malin M.C. and Edgett K.E. Science 288, 2330-2335 (2000).

The author(s) of this abstract have provided an email address for comments about the abstract: forget@lmd.jussieu.fr

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