Extended Data Figure 3.

Comparison between modelled compositions of a vapour depleted liquid and observed planetary compositions. As Figure 3 in main text, but additionally including observed isotope compositions for Mars, and eucrite and angrite parents bodies as well as including elemental and isotopic Fe observations (panels b and d; Fe isotope data from [55] and references therein, all other references as in Figure 3). Comparison of observed Fe contents and isotope ratios are complicated by core formation because most Fe enters the core. In our model we assume that the iron in the core has not been affected by vaporisation, inferred to occur later. For instance, the effect of ~48% Fe loss (panel c) on the current bulk silicate Earth Fe content is dependent on the fraction of Fe that entered the core prior to collisional vaporisation and the oxygen fugacity evolution of the growing Earth. For reference, the datum labelled Fe** in panel d is therefore the Fe/Ca of the bulk Earth (calculated from [56]) instead of the Fe/Ca of the bulk silicate Earth. Similarly, Si can also enter the core, although its quantity is likely <3 wt%⁵⁷. Right pointing arrows in b) and d) indicate the effect of 3 wt% Si in the core (3000 K assumed for metal-silicate Si isotope fractionation factor⁵⁸).