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Study of Martian debris flows

Participants: F. Costard, J. Gargani, G. Jouannic, F. Schmidt, Ch. Marmo

Background

The study of erosion features on the recent Martian slopes is essential to better comprehend the recent climatic variations on Mars. Liquid water is not likely to be found on the surface of Mars because of atmospheric pressure/temperature conditions below water’s triple-point. However, debris flows discovered by Malin and Edgett (2000) suggest that significant amounts of liquid water has flowed on Mars in a recent past. These famous erosion features are among the most youthful features on Mars based on the scarcity of cratered gullies and their superpositions on relatively young formations such as dunes. In particular, the study of the flow morphology along martian slopes like „debris flow“ permits to evaluate role and effectiveness of erosive agents according to morphic caracteristics of the flows (Digital Elevation Model, Cross section, long profil …), nature of flows (fluvial, debris flow, grainflow …) or the mode of erosion and deposition (sinuosity, lateral deposit …). Figure : debris flows in the Russell crater (Mars). Credit: NASA/JPL/Malin Space Science Systems

Methodology

New high resolution images coming from martian orbiter (HRSC camera of Mars Express spacecraft MRO-HiRISE camera) boosted the study of the martian surface mainly thanks to the complementary nature of new datas (images HRSC and HiRISE, Laser altimetry MOLA, Digital Elevation Model HRSC and HiRISE, mineralogical data OMEGA and CRISM …). Thus, we suggest a revision of debris flows study on Mars using these new datas. The high resolution imagery will permit to quantify erosive processes and better forcing different proposed hypothesis. Thise approach will necessarily be a comparative study because martian processes show high analogies, and also important differences with their terrestrial equivalents.

Working plan

On the basis of G. Jouannic’s PhD, we continue studying morphologies of debris flows which occur on slopes in the Russell dune field. The presence of fluid on the Martian surface in recent past, or at present, is strongly controversial. The study of recent formation, like in the Russell crater, could advance the debate (Costard et al., 2002 ; Mangold et al., 2003). Indeed, thanks to the new high resolution images (HiRISE) with spatial resolutions of 25-50 cm/pxl, we can identify more precisely morphologic observations on the dune field between 2007 and 2011. Moreover, using an assemblage of 31 High Resolution Imaginig Science Experiment (HiRISE) images over a 46 months period (November 2006 - August 2010), it’s possible to follow the morphological evolution (and possible change) of the Russell dune over time. Recent work shows that the debris flows located on the Russell dune (54°S, 13°E) are not only extremely youthfull but seem also to be still active (Reiss et al., 2010). A present defrosting activity generates sinuous and branching morphology. The appearance of new incisions into the dune surface implies a flowing material causing the erosion.





IDES Université Paris-Sud 11 CNRS Faculté des Sciences
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