Petrology of Apollo 15 station 9A surface and drive tube soils

Modal analysis data are presented for six samples from the upper part of the Apollo 15 lunar core 15010/011 in order to further investigate the maturation profile of the core and to estimate the source rock contribution. The core data are compared with those of the adjacent soils 15531 and 15601. The soils analyzed are relatively immature and remarkably homogeneous. Surface soil 15531 is the most immature one, which is attributed to the fact that it was sampled from the rim of a relatively recent 3 m-diameter crater and thus contains an admixture of fresh bedrock material ejected by this cratering event. The major source of rock contribution to the soils is from petrographically identifiable mare basalts (about 89% to the core and to 15601 and about 87% to 15531). Olivine basalts and quartz normative basalts occur in an approximate ratio of 3:1; contributions of KREEP basalts and the Front are relatively minor.