51st Lunar and Planetary Science Conference (2020) 1241.pdf POLYGONAL IMPACT CRATERS ON CHARON. C.B. Beddingfield1,2, R. Beyer1,2, R.J. Cartwright1,2, K. Singer3, S. Robbins3, S.A. Stern3, V. Bray4, J.M. Moore2, K. Ennico2, C.B. Olkin3, J.R. Spencer3, H.A. Weaver5, L.A. Young3, A.Verbiscer6, J. Parker3, and the New Horizons Geology, Geophysics, and Imaging (GGI) Team; 1SETI In- stitute, Mountain View, CA, 2NASA Ames Research Center, Mountain View, CA (
[email protected]), 3Southwest Research Institute, Boulder, CO, 4University of Arizona, Tucson, AZ, 5John Hopkins University Applied Physics Laboratory, Laurel, MD, 6University of Virginia, Charlottesville, VA. Introduction: Polygonal impact craters (PICs) re- flect pre-existing extensional and strike-slip faults and fractures in the target material [e.g. 1-9]. PIC straight rim segments therefore can provide important infor- mation for deciphering the tectonic histories of plane- tary bodies [e.g. 8]. The only known PIC formation mechanism is the presence of pre-existing sub-vertical structures within the target material [e.g. 5, 7, 11-13]. In contrast, circular impact craters (CICs) are in- ferred to result from impact events in non-tectonized target material. CICs can also form in pre-fractured tar- get material if the fractures are widely or closely spaced, if the fracture system is highly complex, or if the target material is covered by a thick layer of non-cohesive sed- iment that limits interactions between the impactor and the underlying bedrock/ice [e.g. 14]. Consequently, PICs and CICs are useful tools to distinguish between Fig.