Interpretation of the complex dune morphology on Mars: dune activity, modelling and a terrestrial analogue

Abstract

In this work we analyze a dark erg on Mars that could be considered a mega‐dune (draa) where secondary dunes of different morphology are superposed over a main crescent‐shaped bedform (primary dune). The presence of a complex, multi‐directional wind regime is indicated as one of the main causes for the accumulation of a tall draa, presenting an analogy to the Great Sand Dunes in Colorado. In both cases, main regional winds from the SW blow in opposition to winds from the NE which are enhanced by the topography. Such a complex wind regime leads to the development of star and reversing dunes and is accurately predicted by atmospheric models on a regional and local scale. Signs of activity in the form of grainflow scars are also noted over the slip faces of many dunes, suggesting that easterly winds are actively shaping the study draa in the present‐day climatic setting. The presence of this draa on Mars suggests a complex interaction between regional and local topographically controlled flows and a consistent availability of sand. The future study of an analogue terrestrial site such as the Great Sand Dunes could be fundamental for understanding the evolution of similar Martian dune fields. Copyright © 2012 John Wiley & Sons, Ltd.

Bedform migration on Mars: Current results and future plans

“…Dune ripples, brink and crest profiles, and bedform interference patterns are indicative of complex wind patterns at fine scales. For example, star dunes in Proctor Crater (Fenton et al, 2003) and in several other locations (Hayward et al, 2007;Silvestro et al, 2012) indicate formative winds from multiple directions. Complex patterns of dunes and dune ripples in the north polar erg have been documented (Ewing et al, 2010).…”

Quantifying geological processes on Mars—Results of the high resolution stereo camera (HRSC) on Mars express

“…View is towards the south-southwest; HRSC image and DTM mosaic of orbits h2108_0000, h3253_0000 and h3264_0000; vertical exaggeration is 2.5. Chojnacki et al, 2011bChojnacki et al, , 2012Tirsch et al, 2011;Cardinale et al, 2012;Gardin et al, 2012;Silvestro et al, 2012). HRSC nadir images of up to 10 m/pixel spatial resolution provided excellent overview images for these studies displaying the entire locations with a satisfactory resolution of ground details such as dune size, dune type, slip face orientation (Fig.…”

“…19) and layering sequences. Comparison of slip face orientations on HRSC data with wind direction data from meso-scale to high-resolution general circulation models revealed those dune bodies that have not been built by recent wind regimes (e.g., Tirsch et al, 2006;Gardin et al, 2012;Silvestro et al, 2012). Thus, dunes preserve a record of atmospheric wind conditions and can thus be used as ground truth for global circulations models and climate models (Hayward et al, 2009).…”

“…Complementary HRSC DTMs with spatial resolutions of up to 50 m/pixel were used to analyze the local dune environment as well as the dune morphometry such as the relative surface relief, dune height, and dune slopes (e. g., Chojnacki et al, 2010Chojnacki et al, , 2012Chojnacki et al, , 2014aDiniega et al, 2010;Tirsch et al, 2011;Silvestro et al, 2012). Colorized HRSC perspective views provide instructive figures revealing the relationships between the dunes and their spatial environment (e.g., Chapman et al, 2011;Kereszturi et al, 2011;Tirsch et al, 2011;Silvestro et al, 2012) (Fig. 20).…”

Radar Albedo Feature

“…1, 2, 4) (Fenton et al 2003;Silvestro et al 2012), Aonia Terra, Mars (Silvestro et al 2010) (Fig. 3).…”