Polygonal impact craters on Ganymede

Kurzfassung

Polygonal impact craters (PICs) are unique geological features observed on various planetary bodies and constitute a small percentage of the impact crater population. This study focuses on PICs on Ganymede, where no such craters have been investigated so far. Here we present the distribution of PICs, examine their morphological characteristics, investigate the causes for their polygonal shapes, and discuss the factors that support their formation. We identified and analyzed 459 PICs on Ganymede with complex crater morphologies. They are widely distributed across the Moon and occur on both dark and light terrain. Our analysis revealed that the majority of orientations of straight rim segments align parallel or subparallel to adjacent tectonic linear features. There is at least one tectonic linear orientation adjacent to PICs, even in dark, cratered terrains. Based on the comparison of the number of PICs and tectonic linear features, Ganymede is believed to have undergone more intense tectonic activity than other icy bodies like Ceres and Dione, where PICs were described. The presence of numerous PICs on Ganymede suggests that surface lineations and grooves are expressions of fractures that form zones of weakness in the ice crust that got reactivated during impact cratering.