Trapping and Modification Processes of Noble Gases and Nitrogen in Meteorites and Their Parent Bodies

Abstract

We review the inventories of primordial noble gases and nitrogen in meteorites, their carrier phases, how and where they may have been incorporated, as well as processes modifying their abundances on meteorite parent bodies. Some of the many distinct noble gas and nitrogen components have an isotopic composition very different from that in the Sun. These components reside in presolar grains. “Anomalous” noble gas and nitrogen components thus are used to infer parent stars of presolar grains as well as theories of stellar nucleosynthesis. Other noble gas components have an isotopic signature roughly similar to the solar composition. Some of these “normal” components are also carried by presolar grains and probably approximately represent the average isotopic composition of their parent stars. Carriers of other normal components remain ill-defined and their origin unclear. Their isotopic identity was possibly established in the solar nebula, but it appears increasingly likely that this often also happened earlier somewhere in the presolar molecular cloud. Apart from allowing us to study meteorite formation, primordial noble gases and nitrogen also are important tracers to constrain the metamorphic history of meteorite parent bodies.