A collisional history of the L chondrite parent bodies

Abstract

L chondrites are some of the most common meteorites retrieved on Earth. Their Ar–Ar collision ages indicate a major disruption of their parent body ~470 million years ago (Ma), which was followed by an intense meteorite shower on Earth that is linked to the Ordovician biological crisis. However, recent but previously scarce chronological and geochemical data on a few L chondrites hint at a more complex evolution of the parent body than a single, one-stage 470 Ma break-up. Here we conducted a unique coordinated mineralogical and geochronological study on eight shocked L chondrites, which showed a wide distribution of collisional ages at 4,500, 4,470, ~700, 470 and ~10 Ma. The lower-limit sizes of the parent body derived from shock timescales, combined with the orbital parameters and the aforementioned ages of the meteorites, indicate a complex collisional cascade endured by the parent body of the L chondrites, pointing towards several L chondrite sources in the asteroid main belt, namely, the Nysa–Polana, Juno, Gefion 2 and potentially Massalia asteroid families.