INITIAL GEOLOGIC MAPPING OF THE AC-H-13 URVARA QUADRANGLE OF CERES USING DAWN SPACECRAFT DATA

We are using geological mapping to identify the geologic processes that have modified the surface of dwarf planet Ceres, which NASA’s Dawn spacecraft began orbiting in April 2015. Framing Camera data from the Approach (1.3 km/px) and Survey (415 m/px) orbits, including clear filter and color images and digital terrain models derived from stereo images, have enabled an initial characterization of the surface. Ceres has been divided into 15 quadrangles; this abstract discusses the geology of the Ac-H-13 Urvara Quadrangle, located between 21˚S-66˚S and 180-270˚E.

The Urvara Quadrangle is dominated by the Urvara basin in the east and cratered plains in the west. The elevation of the cratered plains is intermediate between the identified “highland” and “lowland” units of Ceres. Plains in the SW corner of the quadrangle are hummocky and heavily cratered, while the NW corner is smoother and less densely cratered. Features of note include 1) the 200 km diameter Urvara basin, which includes a degraded northern rim and smooth interior and exterior material that hosts a significantly lower impact crater density than most of the rest of Ceres’ surface; 2) semi-radial curvilinear structures extending to the east and west of Urvara; 3) two large-scale dome structures 10s of km in diameter exterior to Urvara; and 4) numerous small-scale domical structures (<12 km diameter) associated with the smooth material interior to the basin. Key goals of the ongoing mapping are to assess the types of resurfacing processes that might be responsible for producing the smooth units, and to assess the processes responsible for the development of large and small dome structures. Future work includes more detailed definition and characterization of surface units and estimates of their compositional variations through study of color images and Visible and Infrared spectrometer data, and application of crater statistical techniques to obtain model ages of surface units.

Support by R. Jaumann, T. Roatsch, F. Preusker, A. Nathues, M.C. DeSanctis, C.T. Russell, C.A. Raymond and the Dawn Instrument, Operations, and Science Teams is grateful acknowledged. This work is supported by grants from NASA through the Dawn project, and from the German Space Agency.