Lunar spinels in the Aristarchus crater and cobra head

Abstract

On the lunar surface we identify and map Mg-spinel-bearing deposits on the southern section of the Aristarchus Plateau, including the Aristarchus and Herodotus craters and the Cobra Head using the color rations C (950-750 nm) and C (2650/1550 nm). The main concentrations of spinel-bearing material are located on the peak and floor of the Aristarchus crater, with some minor deposits also detected on the walls. Most of these deposits are associated with surface areas covered by massive boulders. The crater peak reveals a bimodality of spectral characteristics and surface types: The smooth, darker surface of the northernmost face has a strong absorption band near 1 μm that is evidence of mafic mineral presence. The brighter and rougher surface of the peak midportion reveals absorption starting from 1.55 μm. This suggests a dominant plagioclase/Mg-spinel mineralogic composition of Fe-poor minerals. The Mg-spinel deposits outside the crater are represented by a single unit located on the southern slope of the Cobra Head. The intrusive volcanism and further uplifting by the impact is discussed as a possible origin of the Mg-spinel deposits of the region.