The early evolution of the Solar System witnessed the emergence of planetesimals from dust and gas followed by the assembly of differentiated protoplanets from planetesimals and eventually the coalescence into the embryonic terrestrial planets with approximately their present-day masses and radii. Much remains unclear of the nature of this primordial accretion and evolution. More especially, about the significant role played by volatile elements (H, C, N, S, halogens) that are significant ingredients necessary for the habitability of planets. The storage and cycling of volatiles in Earth and other planetary bodies depend on the structure and stability of volatile-bearing minerals and fluid/melts at high pressure and temperature either at mantle or core conditions. The origin and behaviour of volatiles during Earth’s accretion and its differentiation is determinant but still not well constrained.

This session aims to provide a multidisciplinary view on the earliest stage of the formation, dynamics and chemistry of the Earth and inner planets, and on the modern volatile cycling in the deep Earth.

We welcome contributions that address questions related to the speed of differentiation in small bodies, the fraction of primitive versus differentiated material that coalesced to form the terrestrial planets, the timing of silicate core-mantle separation, the amount of volatiles retained by these planets during the accretion process and the effects of giant impacts.

Therefore petrological, mineralogical, geochemical, experimental, and theoretical contributions on volatiles at high pressure and temperature environments are encouraged, including natural abundances and isotopic signatures, experimental determinations of solubility, speciation, diffusion, phases partitioning and incorporation mechanisms, redox mechanisms affecting the volatile speciation.

Contributions from early career scientists are also welcomed.