Fig. 5.

Modeling of δ¹³C values of the bulk Earth and the core as a function of (i) fraction of remaining C in the mantle during carbon sequestration to the core and (ii) temperature of Fe melt segregation from magma ocean. The δ¹³C of the bulk silicate Earth is assumed to be a mean δ¹³C value of the worldwide diamond (−7.2‰, Fig. 4A). The ¹³C/¹²C fractionation between CaCO₃ or diamond in magma ocean and Fe₃C in Fe-melt is 2–3‰ at 2,400–2,800 °C (Fig. 2). The fraction of remaining C in the mantle is estimated to be in the range 0.1–0.5 (gray area).