Noble gases and H chondrite meteoroid streams: No confirmation

Abstract

Eleven meteorites suggested to belong to a meteoroid stream of 17 H chondrites (cluster 1) have been analyzed for their noble gases. Together with literature data, the noble gas record of all these stones is discussed. Cluster 1 chondrites belong to different chemical‐petrologic types, and three are regolith breccias, as proven by solar type gases. The thermal history of the parent body of cluster 1 stones is not the same for all (as seen in the radiogenic 40 Ar), and diffusive loss of helium in four of them suggests small perihelion distances for these specimens and thus different orbits from the rest of this group. Exposure ages vary between about 4 and 70 Ma. Thus the orbital elements of the stream must have been undisturbed for about 70 Ma. The exposure age distribution of cluster 1 chondrites is not distinct from that of “normal” H chondrites. These data appear inconsistent with the suggestion that cluster 1 chondrites belong to a specific meteoroid stream with very similar orbits.