Stochastic accretion of the Earth.

Chondritic meteorites are thought to be representative of the material that formed the Earth. However, the Earth is depleted in volatile elements in a manner unlike that in any chondrite, and yet these elements retain chondritic isotope ratios. Here we use N-body simulations to show that the Earth did not form from chondrites, but rather by stochastic accretion of many precursor bodies whose variable compositions reflect the temperatures at which they formed.

Conditions and extent of volatile loss from the Moon during formation of the Procellarum basin.

Rocks from the lunar interior are depleted in moderately volatile elements (MVEs) compared to terrestrial rocks. Most MVEs are also enriched in their heavier isotopes compared to those in terrestrial rocks. Such elemental depletion and heavy isotope enrichments have been attributed to liquid-vapor exchange and vapor loss from the protolunar disk, incomplete accretion of MVEs during condensation of the Moon, and degassing of MVEs during lunar magma ocean crystallization.

Volatile loss following cooling and accretion of the Moon revealed by chromium isotopes.

Terrestrial and lunar rocks share chemical and isotopic similarities in refractory elements, suggestive of a common precursor. By contrast, the marked depletion of volatile elements in lunar rocks together with their enrichment in heavy isotopes compared with Earth's mantle suggests that the Moon underwent evaporative loss of volatiles. However, whether equilibrium prevailed during evaporation and, if so, at what conditions (temperature, pressure, and oxygen fugacity) remain unconstrained.

Refined separation of combined Fe-Hf from rock matrices for isotope analyses using AG-MP-1M and Ln-Spec chromatographic extraction resins.

A combined procedure for separating Fe and Hf from a single rock digestion is presented. In a two-stage chromatographic extraction process, a purified Fe fraction is first quantitatively separated from the rock matrix using AG-MP-1M resin in HCl. Hafnium is subsequently isolated using a modified version of a commonly applied method using Eichrom LN-Spec resin.