Wind regime, sediment transport, and landscape dynamics at a Mars analogue site in the Andes Mountains of Northwestern Argentina

The Puna Plateau of northwestern Argentina is a promising region for analogue investigations of Martian aeolian processes owing to its high altitude, low atmospheric pressure, aridity, geology, and widespread granular and bedrock aeolian landforms. Despite a growing body of research about the region's enigmatic aeolian landforms, little is known about the contemporary aeolian environment, processes, and landscape dynamics. To address this gap, we used a combination of modelled weather data, satellite imagery, and field measurements to characterize the wind regime, aeolian sediment transport, and allied surface changes. The study focused on the Campo de Piedra Pómez (CPP) - a volcanic landscape with a variety of Mars analogue landforms: gravel-mantled megaripples, yardangs, ventifacts, periodic bedrock ridges, and aeolian rat-tails. Modelled weather data from the European Center for Medium-Range Forecasting's ERA-Interim reanalysis dataset confirm the contemporary dominance of northwesterly winds in this region, consistent with the primary orientation of yardangs. These data also indicate the presence of less frequent southeasterly winds, which may explain why re-entrant profiles are observed on the southeast flanks of a small portion of the yardang population, and why some aeolian rat-tails point to the northwest. Observations from multi-temporal satellite imagery indicate that deposition and displacement of small sediment patches overlying ignimbrite bedrock is relatively common across the region. Samples retrieved from sediment traps deployed over one year in the region suggest a broad range of particle densities are mobilized by wind, which implies a wide range of wind speed for fluid entrainment. Conventional aeolian transport models do not consider the effects of particle density variations on transport processes. However, in areas with multiple density sediment present, our results point towards a need for aeolian models to consider density when quantifying and qualifying sediment transport.