Orange material in the Sulpicius Gallus formation at the southwestern edge of Mare Serenitatis
Orange and red materials were observed and photographed in the dark mantle of the Sulpicius Gallus Formation on the southwestern rim of the Serenitatis basin. These materials occur only within the dark mantle that overlies old rilled mare and highland units and are absent on the younger mare unit in this area. Orange and red materials occur predominantly as halos, patches, or rays around fresh impact craters ranging in diameter from less than 50 to 250 m and in layers exposed at the base of the dark mantle deposit in the steep walls of a depression and a graben. Red material is present in the highland subsurface, possibly as dikes. We conclude that orange material, locally underlain by red material, occurs in the dark mantle to a depth of about 50 m as locally stratified but discontinuous pyroclastic deposits and that it may have been produced by multiple 'fire foundation' eruptions during the later stages of accumulation of the older mare basalt units.