Fig. 2

Argon three isotope plot for plagioclase-rich lithic fragments. (40Ar/36Ar)m vs. (38Ar/36Ar)m for eleven plagioclase-rich lithic fragments separated from Apollo 17, 78461 regolith sample. The observed variation in (38Ar/36Ar) values can be explained by mixing of non-radiogenic trapped Ar implanted via the solar wind (vertical dashed line 38Ar/36Ar = 0.188 (Eberhardt et al. 1972)) and cosmogenic (38Ar/36Ar = 1.54 (Hohenberg et al. 1978)) 38Ar in lunar plagioclase-rich lithic fragments. m = measured isotopic composition corrected for blank contribution and mass discrimination. The numbers beside the symbols represent the sample names (e.g., 10 represents sample Plag#10)