Figure 3.

Comparison between modelled compositions of a vapour depleted liquid and observed terrestrial compositions. a) Changes in isotope compositions (‰/amu) against total relative vapour loss (F_Total, in mole fractions) calculated in our model. b) Observed terrestrial Mg (this study), and Si (from [4] and references therein) isotope compositions relative to enstatite chondrites (EH). Errors are 2se. c) Loss (mole fraction) of a given element (X), f_X, versus F_Total. d) Molar element/Ca of the terrestrial mantle⁷, normalised to EH³¹. Shaded bands give error bounds for F_Total inferred from Mg isotope data and the intersection of different curves with this field indicates the range of terrestrial depletions predicted for our vapour loss model. Comparison of these values to those calculated for the Earth relative to an enstatite chondrite starting composition (b and d) is generally good, despite uncertainties in model input parameters (see Methods) and additional influences on observed values from nebular and core formation processes⁴,⁹. Left pointing arrows show the effect of post-volatile loss accretion of 20% chondrite (EH).