Radiometric ages of basaltic achondrites and their relation to the early history of the Solar System

Pb-Pb mineral isochrons were determined for three cumulate eucrites (Moama, Moore County, and Serra de Mage) and three noncumulate eucrites (Nuevo Laredo, Bouvante, and Stannern). Two noncumulate eucrites (Bereba and Cachari) show disturbed Pb isotope patterns. The mineral isochron ages of cumulate eucrites range from 4.40 Ga to 4.48 Ga. The latter is the age of Moore County (4.484 +/- 0.019 Ga), which was also dated by the Sm-Nd method at 4.456 +/- 0.025 Ga. Nuevo Laredo and Bouvante give the same Pb-Pb age: 4.514 +/- 0.015 Ga and 4.510 +/- 0.004 Ga, respectively. The Pb isochron of Stannern corresponds to 4.128 +/- 0.016 Ga, which is a reequilibration age. Both Cachari and Bereba show evidence of isotope resetting at about 4 Ga. A Pb-Pb multicorrelation approach is introduced and applied to the data.