Global estimates of lunar iron and titanium contents from the Chang' E-1 IIM data

Until recently, global high spatial resolution maps of FeO and TiO ₂ of the Moon were only derived from Clementine data. In this study, we show global maps of FeO and TiO₂ using Chang'E-1 Interference Imaging Spectrometer (IIM) at a spatial resolution of 200 m/pixel. With a newly developed calibration presented here, spectra obtained by IIM compare well with telescopic spectra. Spectral parameters previously shown to be sensitive to iron and titanium, derived from the calibrated IIM data are highly correlated with the measured elemental concentration with R² = 0.96 for FeO and 0.95 for TiO₂. The maps were developed using this calibration. Histograms of basalt FeO estimates have a negatively skewed distribution, while TiO₂ distributions are unimodal. They also revealed that the lunar highland crust is relatively uniform on the quadrant scale (several hundred to thousand kilometers scale) but inhomogenous on the global scale. The area of highest elevation of the Moon has very low FeO and TiO₂ raising the question about South Pole-Aitken (SPA) (whether its ejecta deposits covered the highest elevation and when it was formed). Although the average FeO and TiO₂ abundances for basalts are highly correlated, local areas of elevated iron can be associated with both high and low titanium.