GEOLOGIC MAP OF NEW HORIZONS' ENCOUNTER HEMISPHERE OF CHARON, II

NASA's New Horizons spacecraft revealed diverse landscapes on Pluto and Charon during its July 2015 flyby, and we have begun geomorphologic mapping to better understand the different landforms, sequence and timing, and how they may have formed. The work herein focuses on Charon, and images from the spacecraft have revealed a variety of features that include hundreds of tectonic manifestations and vast but diverse plains.

For ease of communication, the New Horizons team developed informal names used herein. On Charon, these include two dark macula, 14 impact craters, six chasmata, and three large montes. In addition, the very broad area north of a large tectonic belt has been termed "Oz Terra" and the smoother plains generally south of the belt are "Vulcan Planum."

Initial geomorphologic mapping focused on tectonic features. The majority of tectonic features are aligned northeast-southwest; this parallels the massive tectonic belt implying these features are likely related. Based on superposed, large impact craters, we estimate the majority of the larger tectonic features formed ~4 Ga. However, crater density maps show a deficit of craters in some areas that are possibly due to disruption by tectonic features, indicating that some tectonic activity may be significantly younger.

Vulcan Planum is a younger region than Oz Terra, indicated by the spatial density of large craters. In topography, it shows a "moat" at its margins, possibly indicating a frozen viscous fluid flow. We are in the process of studying this region and the geomorphologic map has revealed only two primary types of landscape: smooth plains, and patterned ground which resembles an elephant skin-like texture. Near its southern margin, it also shows numerous broad warps that may represent upwelling.