Debris Flows on Frozen Arctic Sand Dunes May be Similar to Ones on Mars

Far north in the frozen Arctic, water in the form of snow or frost can melt to form debris flows on sand dunes. Now, scientists have suggested that these debris flows are similar to the dark dune spot-seepage flows on another planet--Mars.

A team of scientists from the Southwest Research Institute (SwRI) first saw these debris flows at the Great Kobuk Sand Dunes in Alaska. This particular site serves as an Earth-based cold-climate "analog" to dunes on Mars. They found that the debris flows formed on days when air temperatures remained below the melting point of water. Very few minutes of above-freezing ground surface temperatures are needed to locally melt frozen water and mobilize sand down steep slopes.

So how do these debris flows work exactly? Fresh patches of wind-deposited dark sand on the bright white snow cause local hot spots. The dark material absorbed the sunlight and conducted it into the underlying snow, melting it. It's very possible that a similar phenomenon occurs on frozen Martian sand dunes.

In fact, the Alaskan debris flows are morphologically similar to small, defrosting-related "dark dune spot" seepage flows that seasonally form in late winter on frost-covered Martian sand dunes. This dark dune spot seepage flow actually gave rise to the popularly known "trees on Mars." This optical illusion was associated with the Mars Reconnaissance Orbiter HiRISE images of the flows.

On Mars, it's likely that the dark dune spots are created when a thin brine layer forms and flows downslope on Martian sand dunes after the seasonally deposited carbon dioxide frost layer has begun to locally sublimate. Because of preferential energy absorption by these dark, ice-free surfaces, localized heating and thawing at scales too small for orbital sensors to identify may yield briny Martian debris flows under current climate conditions.

The findings reveal a little bit more about the debris flows on Mars. In addition, it shows that Earth and the Red Planet share some environmental processes in common. This, in turn, shows that learning more about one planet could reveal further insights into the other.

The findings are published in the journal Icarus.