Fissiogenic xenon from the Pasamonte meteorite

Unambiguous evidence for fission-produced nuclides in meteorites has been shown in the abundance pattern of the Xe isotopes from the Pasamonte meteorite. Calculation of the age of the meteorite from fissiogenic Xe136 and uranium contents of the meteorite yields a value of T′ = 2 × 1010 years, which seems far too large. The result of this calculation leads to the conclusion that part of the fissiogenic Xe in Pasamonte must have been produced by other fissionable nuclide(s), such as Pu244, in addition to U238. Assuming that the fissiogenic Xe136 in Pasamonte is produced from spontaneous fission of U238 and extinct Pu244, then Ξ, the time interval between the cessation of nucleosynthesis and formation of the meteorite, is estimated to be ∼300 m.y.