Time of proto-Earth reservoir formation and volatile element depletion from Mn-Cr chronometry.

The Mn-Cr chronometry of Solar System materials constrains the early chemical evolution of the protoplanetary disk, which is critical for planet formation. Mn/Cr ratios in carbonaceous chondrites and the bulk silicate Earth indicate that meteorite parent bodies and Earth have variable depletions in volatile elements compared to the bulk Solar composition. This depletion is a consequence of the local temperature decreasing as a function of heliocentric distance before planetesimal accretion.