How old is the crater copernicus?
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- Eberhardt, P., Geiss, J., Grögler, N. et al. The Moon (1973) 8: 104. doi:10.1007/BF00562752
Two KREEP glass concentrates separated from lunar soil 12033 have been dated with the Ar39/Ar40 method. Both samples show low-temperature plateaus in accordance with a major outgassing of the KREEP glasses (800 ± 40) × 106 yr ago. This is the age of Copernicus, provided the identification of KREEP glass as ray material ejected during the Copernican event is true (Hubbardet al., 1971). The exposure age of the two KREEP glass concentrates is 200 × 106 yr and thus distinctly smaller than the ejection age. Possible explanations for this are discussed.
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