GEOLOGIC MAPPING OF WESTERN SOUTH POLE-AITKEN USING DATA FROM LRO
For the eastern half of Planck, 18 geologic units were identified along with structural features and 750 primary craters for crater count age estimates. Units include: Mare Ingenii rim materials; Mare Ingenii floor materials; Leibnitz rim materials; Leibnitz floor materials; Poincare rim materials; Von Karman rim materials; Von Karman rim and Leibnitz rim materials; sharp-rimmed, bowl craters; sharp-to-round rimmed craters; complex craters with central peak; crater and ejecta; ejecta; mare materials (1 and 2); cratered plains; plains with Leibnitz ejecta materials; and surficial materials (1 and 2). Several craters (D= ~30-60 km) have well-developed sinuous channels along portions of their interior walls. Wrinkle ridges are apparent near the center of crater Poincare. Individual to branching systems of linear to arcuate rilles (1-100 km) occur mainly on the floors of craters Poincare, Garavito, and Jules Verne. Impact craters larger than 1 km in diameter were counted on all mapped units as a first step in relative age dating of geologic units. Areas with secondaries, secondary chains or clusters were avoided. The N(20) values, combined with the mapped geology, shows that Mare Ingenii and Poincare, have some of the oldest geologic surfaces in the region. This result is reasonable considering that the eastern half of the quad is within SPA, one of the oldest features on the Moon.