Imaging spectroscopy of selected regional dark mantle deposits of the Moon

We present the study of four surface units previously identified as dark mantle deposits on the Moon: Taurus Littrow, Sulpicius Gallus, Mare Vaporum and Rima Bode deposits. The data have been obtained at the 1.5 m telescope of Sierra Nevada Observatory (Granada, Spain) by using an imaging spectrometer working in the 0.4–1.0 μm spectral range. Principal features of these geologic units are: (a) low albedo, (b) localization at the boundaries between highlands and maria, and (c) spectral properties similar to those of the associated mare lavas. The image cubes have been processed by means of two independent statistical methods: the principal components analysis and a supervised clustering technique (spectral angle mapper). Using these methods it has been possible to identify the areas covered by dark mantling material and to compare the different spectral properties of the four deposits. In particular, two different classes of the dark mantle deposits have been detected on the basis of the spectra. New areas in Sulpicius Gallus deposit having intermediate spectral behavior between highland soil and dark mantling material have been identified, probably due to a mixing of the two terrains.