Global Distribution and Geological Features of Ilmenite‐Rich Sites on the Lunar Surface

Abstract We studied the global distribution and geological features of lunar surface sites whose spectra indicate an ilmenite‐rich composition. Hyperspectral data obtained by the Kaguya Spectral Profiler were used for data mining to identify diagnostic features of a 1‐ and 2‐m spectral reflectance of ilmenite, revealing the global distribution of sites showing ilmenite‐rich spectra. The results show that regions with ilmenite‐rich spectra are concentrated at the margins of impact basins on the lunar nearside, whereas no such regions are identified in the Feldspathic Highland Terrain or the South Pole‐Aitken basin. Using multiband images and a digital terrain model obtained by the Kaguya Multiband Imager and Terrain Camera, we examined the geological features of each site showing ilmenite‐rich spectra and found that most of the sites are distributed on pyroclastic deposits overlying highland materials. Spectra interpreted as glass‐rich material are prevalent in and around areas having ilmenite‐rich spectra. However, sites showing ilmenite‐rich spectra do not correspond to mare regions with ‐rich basalts. These results may indicate that the concentration of ilmenite in pyroclastic deposits is high enough to exhibit diagnostic features of 1‐ and 2‐m spectral reflectance of ilmenite, whereas the concentration in mare regions with ‐rich basalt is not. Since pyroclastic deposits are expected to be extensive, deep unconsolidated deposits of relatively block‐free debris, resulting in high processing efficiency in the hydrogen reduction processes, our data may be useful for developing an efficient exploration strategy for ilmenite as a lunar resource.