Particle track based irradiation and accretion history of the Luna-24 regolith column

Abstract

Regolith materials from Mare Crisium, sampled by the Luna-24 deep drill core, have widely varying cosmic ray irradiation records, as revealed by the particle track records in six samples taken from different depths in the core. The observed track records are typical of mare materials and are similar to those observed in Apollo 12 and 15 sites. The soils in the upper zone (74-162 cm) of the drill core column consist of highly mature to submature soils, whereas there is a preponderanceof immature soils in the lower zone (162-208 cm). The track data are consistent with either a slow deposition rate or a high level of pre-depositional irradiation for the regolith material in the upper zone and a fast deposition rate for the lower part of the regolith column at this site.