Terrestrial Krypton and Xenon: Are These Freaks?

Variations of the isotopic compositions of spallation-corrected Kr and Xe in the solar system have been called a Pandora\u27s Box. The terrestrial Xe composition has been interpreted as mass-fractionated solar Xe or, alternatively, Ur-Xe plus Pu-244 fission. A major problem of these ideas is that terrestrial Kr and Xe cannot have been fractionated simultaneously by a simple process. One must invoke multistep sequences involving the Earth during planetary times.This raises the following issue. Are terrestrial Kr and Xe freaks which nature has only generated once and only in one place of our galaxy, or are they not