THE ARGENTINEAN PUNA: AN AEOLIAN WONDERLAND AND PREMIER MARS ANALOG TERRAIN

A major problem in understanding the Martian aeolian system is determining how the interplay of fundamental physical factors (gravity, atmospheric density, frequency of winds above threshold, etc.) drive the formation of landforms that bear both commonalities and distinct differences with those on Earth. Many dunes and dust deposits have, to some degree, common analogs on Earth where they are better understood. In contrast, the origin of Martian megaripples and extensive sand-abraded landscapes, terrains that dominate much of the Martian surface, is less certain. A major hindrance to advancing our understanding of these Martian features and processes has been the lack of a suitable terrestrial analog where field measurements can inform formative conditions and rates on Mars. Recent work shows that the Argentinean Puna, which has been described as an aeolian geomorphology “perfect storm” may fill this gap. Here a bedrock lithology susceptible to aeolian sculpting dominates the surface of a wind-dominated hyper-arid, high-altitude, cold desert. This has resulted in a veritable aeolian wonderland dominated by yardangs, gravel megaripples, and bedrock ridges. Nathan Bridges was a key member of this team and we continue the work in his memory.

Our current work is informed by a series of questions, including:

1. What are the wind characteristics and required wind speeds that drive gravel movement?
2. What is the saltation regime that motivates the movement and accumulation of gravel bedforms?
3. What are the rates of migration and growth of gravel megaripples?
4. What do the transport paths of the gravel clasts look like and how is that related to the saltation and creep regimes?
5. How does the meter-scale topography of the bedforms impact wind regime, saltation regime and gravel megaripple formation
6. And, most importantly, what is the applicability and implications for Mars.

We will present an update of our recent efforts.