Origin and Early Differentiation of Carbon and Associated Life-Essential Volatile Elements on Earth

coef fi cients and solubilities of LEVEs in the silicate melts to examine the effect of core formation, with varying degrees of alloy – silicate equilibration, with or without loss of an early atmosphere formed via MO degassing on the remnant abundances of LEVEs in the bulk silicate reservoir. (a) LEVEs, when delivered as 0.015 M E late-accreting materials (i.e. 0% alloy – silicate equilibration), cause the volatile abundance to be higher than the present-day BSE. Core formation with increasing degrees of alloy – silicate equilibration increasingly the remnant MO in all LEVEs, with C being much more depleted than other LEVEs, leading to subchondritic C/N, C/H, and C/S ratios. (b) Combining early atmospheric loss with core formation cannot offset C loss to the core due to the lower solubility of C relative to the other LEVEs in the silicate MOs. Bulk Earth volatile abundance data are from McDonough, 83 while the alloy – silicate partition coef fi cients in a deep MO (P = 50 GPa, T = 3500 K; e.g. Siebert et al. 104 ) for C, N, S, and H are from the parametrized relationships of Chi et al., 71 Grewal et al., 105 Boujibar et al., 106 and Clesi et al., 107 respectively. Solubility constant data for C, N, S, and H in the silicate melt are from Armstrong et al., et O and