Morphology of Small-Scale Patterned Ground in Utopia Planitia, Mars: A Comparison With Terrestrial Polygonal Terrain

Small-scale polygons on Mars (<300 m diameter) are often considered analogous to patterned ground on Earth. While the polygons appear similar to terrestrial polygons, their formation remains ambiguous. A survey of narrow angle images from the Mars Orbiter Camera identifies over 600 localities with small-scale (30-200m) patterned ground. Roughly 80% of these polygons are located south of 60° S latitude, in a region rich in hydrogen, supporting a periglacial origin. Of the remaining polygons in the northern hemisphere, over 70% of the small-scale polygons are clustered within Utopia Planitia and do not coincide with near-surface hydrogen enrichment. The absence of ground ice may imply either a different formation process or climate change in the Utopia region. This study investigates the 63 polygon localities in Utopia Planitia in detail, in an attempt to differentiate between periglacial, desiccation, and tectonic origins. Preliminary geometric analyses reveal that a majority of crack intersections are orthogonal, and are aligned in a N/NE direction. Some elongation of polygons on slopes is observed, supporting a periglacial origin. When scalloped depressions are found in conjunction with patterned ground, polygons are preferentially found on the higher, undisturbed surfaces. Results from this study will be compared with similar scale terrestrial polygons, including those formed by both desiccation and periglacial processes.