Trapped xenon in ordinary chondrites

Abstract

A trapped component of heavy noble gases representing a distinct solar system (presumably asteroid belt) reservoir is known to be concentrated in carbonaceous carriers of chondritic meteorites. The isotopic signature of trapped Xe in separates of the H4 chondrite Forest Vale (FV) was determined by combusting its carrier phases at 600°C in oxygen, discriminating against in situ produced nucleogenic components which are released above 600°C. The isotopic abundances of FVC (combustion)‐Xe are compared to signatures of bulk trapped Xe in chondritic meteorites. We conclude that FVC‐Xe represents the predominant trapped component in ordinary chondrites (OC) for which we adopt the term OC‐Xe. Its isotopic signature differs from Xe in ureilites, in “average carbonaceous chondrites”, in Earth's atmosphere, and in the solar wind. Additional minor Xe components were identified in type 3 chondrites and in the metal phase of chondrites. We discuss relationships among solar system Xe reservoirs and show that the OC‐Xe signature is consistent with a mixture of HL‐Xe with slightly mass fractionated solar‐type Xe.