Formation of cycloidal dust devil tracks by redeposition of coarse sands in southern Peru: Implications for Mars

Aeolian processes are the most active processes modifying the surface of Mars under present day climatic conditions. Besides wind streak changes and dune and ripple migrations, active dust devils occur frequently leaving numerous tracks on the Martian surface. These dust devil tracks (DDTs) are characterized by albedo changes with respect to their surroundings and are suggested to be caused by erosion of dust exposing coarser grained material. Here we show that DDTs with a cycloidal pattern analyzed in situ in southern Peru are formed by erosion of very coarse sands at the outer margins and its subsequent annular deposition in the central parts of dust devils. Field observations are supported by large-eddy simulations using typical dust devil parameters resembling the cycloidal morphology of the DDTs. Cycloidal DDTs observed on Mars resembling the Peruvian DDTs suggest an equivalent formation mechanism. Our results imply that the formation of DDTs on Mars are not solely due to dust erosion but also depositional processes and dust devils are strong enough to redistribute coarser grained material such as sands; hence they might contribute to the modification of the present day Martian landscape.