Reconstruction of Pluto's Tectonic History Using Polygonal Impact Craters

Abstract

Polygonal impact craters (PICs), impact craters with straight rim segments that reflect pre‐existing structural weaknesses in the target, are used to infer otherwise hidden tectonic patterns on planetary bodies. The New Horizons mission returned high‐resolution imagery of Pluto's encounter hemisphere, and geological mapping has revealed diverse terrains and complex tectonic deformation. However, PICs have not been systematically categorized or mapped on Pluto, and their relationships to tectonic structures remain unexplored, particularly where crosscutting relationships can constrain the relative timing of deformation within Pluto's geologic history. Crater rims were systematically mapped on Pluto, and 1,245 of 1,775 craters (∼70%) larger than 3 km in diameter were classified as PICs, exhibiting at least one straight rim segment with a consistent azimuth over a substantial segment length. A total of 22,174 km of straight rim segments were extracted, and all show preferred azimuths across various geologic regions, revealing multiple local and regional tectonic patterns. 13 out of 154 fully preserved craters (∼8%) exhibit a non‐uniform rim azimuth distribution. Crosscutting relationships between PICs and tectonic structures provide relative age constraints and allow reconstruction of tectonic evolution. In particular, PICs reveal a widespread and ancient radial pattern associated with Sputnik Planitia loading, suggesting a thicker elastic lithosphere that progressively thinned over time and has implications for Pluto's thermal evolution and potential ancient cryovolcanism. Future analyses and modeling are needed to further explore the broader implications of these results for Pluto's tectonic, thermal, and geodynamic evolution.