Geochemistry: how well can Pb isotopes date core formation?
basic_science · Level V
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Abstract
Timescale and the physics of planetary core formation are essential constraints for models of Earth's accretion and early differentiation. Wood and Halliday use the apparent mismatch in core-formation dates determined from tungsten (W) and lead (Pb) chrono-meters to argue for a two-stage core formation, involving an early phase of metal segregation followed by a protracted episode of sulphide melt addition. However, we show here that crust-;mantle Pb isotope systematics do not require diachronous core formation. Our observations indicate that very early (< or = 35 Myr) core formation and planet accretion remain the most plausible scenario.