Xenon in Carbonaceous Chondrites

Origin of xenon-124 and -126 in carbonaceous chondrites.

“…The first such anomaly for xenon was noted by Reynolds (1960) and others many years ago (see, for example, Reynolds and Turner, 1964;Manuel et al, 1972). However, it was not until 1973, when Clayton et al (1973) found carbonaceous chondrites contained oxygen with anomalous isotopic composition, that the overall view of xenon isotope variances as an isolated or `anomalous' case was abandoned .…”

Plutonium-244 in the early solar system and the Pre-Fermi natural reactor.

“…Manuel et al (1972b), for example, argued that carbonaceous chondrites contained isotopically distinct components which could not be explain ed by the occurrences of nuclear or fractionation processes within these meteorites and suggested that the large excesses of fission xenon found in these meteorites may be the product of galactic nucleosynthesis, which had not been uniformly mixed with the solar system materials (see also Sabu et al, 1974;Manuel and Sabu, 1975;Sabu and Manuel, 1980). Anders et al (1975), on the other hand, Burbidge et al (1957), Fowler (personal communication, 1966 speculated that one of the unknown superheavy elements (element 115, 114, or 113) may have had an isotope with a half-life in the range of 107 to 108 years, which is too short to survive to the present day, but long enough to leave detectable effects in meteorites, and this isotope may have been present in the carbonaceous chondrites and decayed to 131-136Xe by spontaneous fission (see also Lewis et al, 1975).…”

Terrestrial-type xenon in sulfides of the Allende meteorite.

“…Later it was found that excess 124Xe and 126Xe always accompany the excess 134Xe and 136Xe of CCF Xe (Manuel et al, 1972), and it was noted that these may be from a supernova explosion, where 124Xe and 126Xe are produced by the p process; 134Xe and 136Xe by the r-process (Burbidge et al, 1957). Xe enriched in r and p products of nucleosynthesis was labeled Xe-X (Manuel et al, 1972).…”

“…In addition to Xe-T, other examples of isoto pically anomalous xenon trapped in Allende and other primitive carbonaceous chondrites are Xe-S (Srinivasan and Anders, 1978) and Xe-X (or Xe HL) (Manuel et al, 1972 i) Lewis et al (1975) first isolated mineral fractions of Allende that contained Xe-X. In these separates, isotopic ratios of the high-Z noble gases, Ar, Kr and Xe, correlate linearly with relative abundances of the low-Z noble gases, He and Ne Sabu, 1975, 1977).…”