¹Jesse T. Gu, ¹Rebecca A. Fischer, ¹Lucy Jacobsen, ¹Michail I. Petaev
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2026.01.013]
¹Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
Copyright Elsevier

Moderately volatile elements are depleted in the Earth relative to chondrites, but it remains uncertain to what extent these depletions of siderophile volatile elements are controlled by volatility versus core formation. Here, we report new metal–silicate partitioning experiments on Pb at pressures and temperatures up to 65 GPa and 5520 K, respectively. Combined with other moderately volatile elements, we use core formation models to show that homogeneous volatile accretion results in an overabundance of volatile siderophile elements relative to lithophile elements in the bulk Earth. Late volatile addition with metal–silicate equilibration at higher pressures and temperatures could potentially resolve this discrepancy by lowering bulk Earth abundances of volatile siderophile elements to be within uncertainty of the lithophile volatility trend. However, uncertainties in core formation parameters, element volatilities, volatile loss mechanisms, and the lithophile volatility trend complicate this interpretation. Our data support a relatively larger role for volatile depletion than for core formation in establishing the Pb content of the bulk silicate Earth.