Spectral Analysis of Mare Ingenii Basin (Lunar Farside)

Abstract

AbstractMare Ingenii is a site of great interest for lunar geology as it is one of the few basaltic plains on the farside of the Moon. It is located within the outer edge of the South Pole‐Aitken basin, the largest and oldest impact basin in our Solar System. Mare Ingenii includes two large craters, Thomson and Thomson M, and a prominent swirl, a high‐albedo sinuous feature whose origin is still debated. We conducted spectral analysis on 28 selected regions of interest within Mare Ingenii, with the aim of inferring its mineralogy. We considered reflectance data acquired in the visible to near‐infrared spectral range by the Moon Mineralogy Mapper (M3) imaging spectrometer onboard the Chandrayaan‐1 mission, to derive a set of spectral parameters. Our results show wide compositional variability, with the dark material of the mare basaltic floor showing the centers of the Fe2+ absorption bands of the pyroxenes shifted toward long wavelengths (0.96–0.99 and 2.03–2.12 μm, respectively), consistent with the spectral characteristics of high‐Ca pyroxenes (as well as swirl material and intermediate albedo regions). In contrast, the bright material of the small surrounding craters shows Fe2+ absorption bands shifted toward short wavelengths (0.91–0.94 and 1.91–2.04 μm, respectively), more consistent with low‐Ca or Ca‐free pyroxenes. The obtained results suggest a mafic signature throughout the surface of Mare Ingenii, probably representative of the composition of the lower lunar crust.