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CitationLorenzetti, S., Busemann, H., & Eugster, O. (2005). Regolith history of lunar meteorites. Meteoritics & Planetary Science, 40(2), 315-327.
PublisherThe Meteoritical Society
JournalMeteoritics & Planetary Science
AbstractThe regolith evolution of the lunar meteorites Dhofar (Dho) 081, Northwest Africa (NWA) 032, NWA 482, NWA 773, Sayh al Uhaymir (SaU) 169, and Yamato (Y-) 981031 was investigated by measuring the light noble gases He, Ne, and Ar. The presence of trapped solar neon in Dho 081, NWA 773, and Y-981031 indicates an exposure at the lunar surface. A neon three-isotope diagram for lunar meteorites yields an average solar 20Ne/22Ne ratio of 12.48 +/- 0.07 representing a mixture of solar energetic particles neon at a ratio of 11.2 and solar wind neon at a ratio of 13.8. Based on the production rate ratio of 21Ne and 38Ar, the shielding depth in the lunar regolith of NWA 032, NWA 482, SaU 169, and Y-981031 was obtained. The shielding depth of these samples was between 10.5 g/cm2 and >500 g/cm^2. Based on spallogenic Kr and Xe, the shielding depth of Dho 081 was estimated to be most likely between 120 and 180 g/cm^2. Assuming a mean density of the lunar regolith of 1.8 g/cm^3, 10.5 g/cm^2 corresponds to a depth of 5.8 cm and 500 g/cm^2 to 280 cm below the lunar surface. The range of regolith residence time observed in this study is 100 Ma up to 2070 Ma.