60Fe in eucrites

Additional evidence for the existence in the early solar system of live ⁶⁰Fe has been found in the basaltic achondrite Juvinas. The relative abundance of ⁶⁰Fe/ ⁵⁶Fe of x0223C; 4 × 10 ^-10 at the time of meteorite solidification is one order of magnitude lower than that previously observed for the eucrite Chervony Kut. This difference corresponds to a ∼ 4.7 Ma time interval between closure of the ⁶⁰Fe- ⁶⁰Ni isotopic system in the two meteorites. The factor two higher initial ⁶⁰Ni/ ⁵⁸Ni ratio in Juvinas is consistent with this time difference and a common bulk Fe/Ni ratio in the two meteorites. Using the ⁶⁰Fe- ⁶⁰Ni isotope system as a chronometer various models for the evolution of the eucrite parent body of different degrees of complexity are discussed. Regardless of the detailed differences between these models a short time interval of only a few million years between planetary differentiation and basaltic crust formation is indicated.