Morphology and distribution of Martian wedge dunes and their terrestrial analogs

Wedge dunes are widespread on Mars and contain important information about Mars surface processes and environmental characteristics. These dunes are wedge-shaped in plan-view, similar in scale to a barchan dune, with two slip faces intersecting at an obtuse angle and extending outward toward the main ridge downwind. And, the length of its main ridge does not exceed its width. At present, our understanding of wedge dunes and their development in nature is limited. The type, morphology, distribution and spatial composition of wedge dunes on Mars and Earth were investigated using high-resolution satellite image data. The results reveal that wedge dunes are simple in type and similar in size to barchan dunes. Martian wedge dunes are similar in shape to terrestrial wedge dunes but larger in size. The average angles between the sub-ridges of Martian and terrestrial wedge dunes are similar, at about 116°. Martian wedge dunes are mainly located in Abalos Undae, Siton Undae, and Aspledon Undae in the North Polar region, accounting for about 5% of the total area covered by dune fields. Wedge dunes are rare on Earth and can only be found on the edge of a few contiguous dune fields. These dunes indicate acute bimodal or obtuse bimodal wind regimes. Wedge dunes have distinct transitional characteristics and may be the initial stage of the development of various dune patterns. The implications of these findings are discussed, in particular the periodic changes in the regional wind direction reflected by the wedge dunes, as well as the significance of the distinctive transitional features of the wedge dunes for improving our understanding of the genesis of complex dune patterns.