Polygonal Impact Craters in the Thaumasia Minor, Mars: Role of Pre-existing Faults in Their Formation

Terrestrial planets, dwarf planets and moons (natural satellites) in the solar system have undergone meteoric impacts since their formation. The craters formed due to such impacts may show various geometric shapes. Formation of impact craters that are polygonal in shape is controlled by the presence of pre-existing tectonic features in the area of impact. Thaumasia Minor, the easternmost part of Thaumasia Planum of Mars, has ~ E–W-trending grabens and ~ N–S-trending wrinkle ridges, similar to the rest of Thaumasia Planum. The massive weight of the Tharsis Montes, lying to the northwest of Thaumasia, is considered as the primary cause for the extensional and compressional fractures developed in multiple temporal phases throughout the geological history of Mars. Five such polygonal impact craters in the southern Thaumasia Minor were compared with the visible expressions of tectonic planes in the region. The straight segments of the craters are also used as a proxy to reveal the presence and possible orientations of buried weak planes in the region.