Ar-39-Ar-40 Ages of Eucrites and the Thermal History of Asteroid 4-VestaNew Ar-Ar ages of several cumulate and unbrecciated eucrites cluster at approx.4.48 Gyr. We suggest that this age cluster was produced by interruption of eucrite metamorphism within the Vesta parent asteroid by a giant impact, which excavated and rapidly cooled these meteorites. We see no evidence for younger formation ages of the cumulate eucrites, as previously proposed.
Bogard, Donald (NASA Johnson Space Center Houston, TX, United States)
Garrison, Daniel (NASA Johnson Space Center Houston, TX, United States)