Evolution of polygenic debris flows on a sand dune (Russell crater, Mars)
Résumé
Recent work has shown that gullies are among the most youthful features on Mars [1] and have been taken as evidence for significant amounts of liquid water in the recent past. Recent studies show that the gullies located on the Russell Crater dune are not only extremely youthful but also appear to be still active [2]. Here we report of a polygenic evolution of debris flow dunes with two phases: 1/ debris flows on hill slopes in recent Martian times (less than 10 My) could be formed by (i) runoff and debris flows with liquid water from groundwater aquifers [1]; [3], (ii) snow-melt ([4]; [5], (iii) various CO 2-driven mechanisms ([6]; [7]; [8]) or (iv) melting of near-surface ground ice (< 1m meter) at high obliquity [9]; 2/ defrosting activity at present time with formation of relatively small sinuous hand branching channels.
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