AEOLIAN-DRIVEN LANDSCAPE EVOLUTION ON MARS

The last decade of Mars exploration has revealed that the current atmosphere is capable of moving surface sediment. Notably, aeolian bedform activity is occurring on the surface today, which has implications on local wind regimes and landscape evolution. Indeed, aeolian processes have likely been the default geomorphic agent for most of Mars’ history, in contrast to the Earth where aqueous processes dominate.

Here, we discuss new results related to active bedforms and their impact on the surface. For this task, we have utilized multi-temporal images acquired annually by the HiRISE camera (25 cm/pix) along with co-located HiRISE Digital Terrain Models (1 m post spacings).

Sand dunes across Mars are found migrating at rates between 0.3-3.0 m/yr. These rates coupled with associated dune heights of 1-40 meters yield typical sand fluxes of 3-12 m³/m/yr. For context, these values are often an order of magnitude less than for dunes on Earth.

Dunes are found associated with craters, canyons, fossae, patera, basins, and extracrater terrain. These terrains are frequently found in the presence of streamlined landforms such as knobs and yardangs, often carved out of sedimentary units. Finer-scale aeolian abrasion features are found at rover sites with ventifacts on rock faces.

Active dunes and the abrasion susceptibility (Sa) of rocks are relevant to assess erosion rates. Using the methodology and assumptions (Sa for basalt, mean trajectory height etc.) described in Bridges et al. (2012), we estimated abrasion rates of local basaltic bedrock to be 0.1–16 μm/yr for flat ground and 4–80 μm/yr for a vertical rock face. For example, active dunes within Becquerel crater are estimated to be contributing to down cutting of yardangs at rates within this range. Rates extrapolated over time would produce 1–80 m per Myr of erosion, similar to earlier independent assessments. Rates would be greater for sedimentary terrains or during periods of higher obliquity and associated higher winds. Additionally, recent studies have suggested certain geomorphic boundary conditions are more conducive to higher fluxes and erosion rates. Landscape evolution on Mars is likely to be accentuated or muted given certain combinations of sediment fluxes, orbital parameters, and terrain geology. Future efforts will be employed in understanding these factors.