Description:
Early and recent work on Pu-Xe dating of achondrites (eucrites) is discussed here; the latter has focused on establishing the time of closure for Xe, not on the estimation of the time interval between the cessation of nucleosynthesis and the crystallization of solid bodies in our solar system. By using various Angra dos Reis dates as standard, the Xe closure of some eucrites was found to be early in the solar system, about 4.56 Gyr ago, synchronous within error with chondrites. The light cosmic ray-produced Xe isotopes were found to be a good surrogate for the Nd content. Using the measured cosmic ray exposure age allows accurate closure times to be established. Combining this new information with data from CAIs and chondrules and chondrites suggests that the achondritic differentiation was accomplished within about 10 Myr or less. Pu-Xe dating in chondrites is not covered in this review.
