GEOLOGIC MAPPING OF THE COPERNICUS LUNAR QUADRANGLE: DETERMINING THE SOURCE OF THE GEOCHEMICAL ANOMALY AT TIMOCHARIS CRATER

The recent flood of lunar data has provided unprecedented views of the lunar surface, which in turn has shown us that portions of the lunar surface, such as the Copernicus lunar quadrangle, contain numerous lunar lithologies with several possible origins. In an effort to provide a comprehensive understanding of the evolution of the lunar crust within the Copernicus quad, we are integrating multiple data sets to conduct an intensive morphologic and compositional mapping program, which will allow us to: (1) examine the heterogeneity of lunar crustal materials and their vertical and horizontal distribution and (2) assess the spatial and temporal variation of lunar lithologies within the quad. Using compositional data sets, such as Lunar Prospector Gamma Ray and Neutron Spectrometer elemental data, we directed our focus to an area of interest that exhibits anomalous compositional characteristics (i.e., low iron abundances and elevated thorium abundances) compared to the surrounding terrain. This area of interest is dominated by Timocharis crater, a 34 km diameter crater located at 26.72°N and -13.1°E, which has slumped interior walls, a central peak, and ~1 km of rim relief. Using high-resolution data from the Lunar Reconnaissance Orbiter Camera we conducted an initial morphologic study of Timocharis, which in turn showed us that there are several unique features that could be the sources of the anomalous geochemical signatures seen in the region. These unique morphologic features include an unusually shaped central peak that may have experienced an impact event, and several small (≤ 1.25 km diameter), higher-albedo, domical features at the base of the western crater wall with meter- to decimeter-sized rocky debris superposed on the finer-grained, surface materials. We are in the process of using forward modeling approaches to estimate the thorium and iron abundances of individual features within the crater. The results of this investigation will help develop and/or refine unit descriptions in order to ascertain the relative ages of unique features. These results will help determine if features within Timocharis are lithologically unique, which in turn will have implications for crustal formation mechanisms within the quad.