Parent bodies of L and H chondrites: Times of catastrophic events

Abstract— An analysis of the distribution of ³He and ⁴He in L and H chondrites has shown that the parent body of L chondrites underwent a catastrophic collision in space 340 ± 50 Ma ago. This age differs considerably from the collision age of 520 ± 60 Ma given previously (Heymann, 1967). The parent body of H chondrites may also have undergone local heating and degassing ～200 Ma ago. Data for L chondrites argue in favour of Antarctic and non-Antarctic meteorites having originated from a common parent body.