Prolonged magmatism on 4 Vesta inferred from Hf–W analyses of eucrite zircon

Abstract The asteroid 4 Vesta is the second most massive planetesimal in the Solar System and a rare example of a planetary object that possibly can be linked to a specific group of differentiated meteorites, the howardite–eucrite–diogenite suite. The 182 Hf– 182 W chronometry of individual zircon grains from six basaltic eucrites revealed distinct growth episodes ranging from 4532 − 11 / + 6  Ma to 4565.0 ± 0.9  Ma and constrains the early thermal history of 4 Vesta, indicating that its mantle generated basaltic melts for at least 35 million years (Myr). Initially, the energy needed for melting was provided by decay of short-lived isotopes, mostly 26 Al. The long duration of magmatism despite the short lifetime of 26 Al implies that the asteroid must have accreted within the first ∼4 Myr of Solar System formation, similar to the formation of iron meteorite parent bodies, and that its interior must have been thermally well insulated by an early-formed crust that prevented heat loss.