Mercury's Tectonics Record a Damage Zone From the Caloris Basin‐Forming Impact

The Caloris basin is the largest of the well‐preserved basins on Mercury and has left a dominant mark in the planet's geologic record. Previous analysis of orientations of a global compilation of Mercury's faults hypothesized that the Caloris basin‐forming impact introduced a widespread damage zone from which basin‐radial and ‐concentric fractures were reactivated as thrust faults by global contraction. Here, we test this hypothesis by expanding the analysis to straight rim segments of polygonal impact craters, which also show a global distribution across Mercury and, on the basis of crater degradation state, host useful stratigraphic information. We statistically assess orientations of fault segments and two populations of straight rim segments of polygonal impact craters: those with degradation characteristics consistent with pre‐Caloris emplacement and the other with post‐Caloris emplacement. We also extract basin‐radial and ‐concentric orientations from the data sets that could host Caloris impact damage to investigate the spatial density of structures and locate geographic regions that stand out from observations reflecting randomly sampled orientations given the natural variation of the data. We find that comparison of statistically derived modes in the orientation distributions to basin‐radial and ‐concentric orientations alone does not unequivocally reveal a damage zone, especially when combined in a global assessment. However, our analysis investigating regional details reveals that there may be a higher structure spatial density in latitudes and longitudes surrounding the basin and its antipode, and that a signature of the damage zone is likely asymmetric, hinting at an oblique impact from the northeast.