Distribution and Origin of Primordial Helium, Neon, and Argon in the Fayetteville and Kapoeta Meteorites

Abstract

Primordial helium, neon and argon have been extracted from polished sections of the Fayetteville and Kapoeta meteorites by a laser microprobe and analyzed mass spectrometrically. The concentration of primordial gas is extremely variable between different portions of dark phase in the same meteorite sample. The maximum concentration of primordial gas is found in fine-grained matrix material. In the Fayetteville samples, fine-grained matrix material within a vein contains an He4 concentration of 10−1−10−2 cm3/g(s.t.p.).In the Fayetteville meteorite, the location and concentration of the primordial gas are consistent with the saturation level of He4 in interplanetary dust irradiated by the solar wind, as discussed by Mazor and Anders. Furthermore, the He4/Ne20 and Ne20/Ar36 are inversely correlated, which can result only from the addition of unfractionated (solar) Ne to varying amounts of fractionated Ne, as suggested by Pepin. This would support also the contention of Müller and Zähringer that the primordial gases were introduced via a carrier, although the chemical composition of this fine-grained material is as yet unknown.Variations in the relative abundances of primordial He, Ne, and Ar within the fine-grained material of Kapoeta can be explained as a result of heating, although the time and mechanism of this event remain obscure.KeywordsSolar WindDark PhasePolished SectionIsotopic AbundanceInterplanetary DustThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.