Spectral Evidence for Recent/Ongoing Activity in Mercury’s Praxiteles Basin

Abstract Mercury’s surface, as revealed by the MESSENGER probe, lacks distinctive absorption features in the visible–near-infrared spectral range, except for hollows that display a 630 nm feature ascribed to sulfides. The general absence of spectral features makes inference of its surface mineralogical composition challenging. We inspected the Praxiteles impact basin with newly photometrically corrected MDIS data, removing the influence of topographic shading in the spectra. We detected an 830 nm absorption feature, spectrally compatible with low Fe content minerals. The morphological and spectral correlations suggest that the 830 nm band is linked to geologically recent, or even ongoing, exposure of material, as well as to the early stage of hollow formation. These results provide insight into the subsurface composition of Mercury and imply a crust material locally more oxidized than previously thought.