Geodynamical Implications of Late Accretion

Late accretion significantly affected the thermodynamic evolution and differentiation of the Earth, Moon and other terrestrial planets. The objective of project area C is to investigate ...

    how material delivered by the Moon-forming giant impact and the subsequent addition of material (the ‘late veneer’) was incorporated into the Earth and Moon

    • how boundary conditions of the giant impact, including the presence of magma oceans affected the distribution and segregation of metal (or sulphide) melt into the core, the compositional heterogeneity of the mantle and its subsequent thermochemical evolution,
    • how abundances of siderophile elements in the silicate fractions of terrestrial planets (and the Moon) were affected by metal-sulfide-silicate fractionation during late accretion and core formation, and finally,
    • how dynamic processes associated with the cooling history of the Earth and Moon are coupled with outgassing of volatiles and the formation of an early steam atmosphere.

    The goal is to reconstruct the late accretion phase and its implications for the evolution of the Earth-Moon System (at a later stage also for small terrestrial planets) by developing models that are consistent with geochemical and geochronological data for the Earth and Moon. To achieve this goal we strive to obtain a comprehensive understanding of

    • how partitioning and chemical equilibration processes at low- and high-pressure- temperature conditions affect the distribution of siderophile volatile elements in planetary mantles and crusts (C1, C2),
    • the thermal and mechanical consequences of giant impacts such as the Moon-forming event (C2, C3, C4),
    • the thermochemical evolution of magma oceans (C4, C5) and the implications for the stability of a crust and lithosphere in the context of late accretion (A projects),
    • the interaction and behaviour of metal or sulphide melt during transport in convecting silicate magma (C1, C2, C3), and finally,
    • the formation of an early atmosphere (C5) and its feedbacks with the cooling interior (C4).

    The interdisciplinary approach combines laboratory experiments (C1) and the analysis of sample material from Earth and Moon (C3, B1, B4 and literature data) with numerical modelling of the dynamic processes, including simulations of hypervelocity impact (C2, C4), mantle convection and differentiation (C2, C4), as well as mantle degassing and atmospheric evolution (C4, C5). Experimental and observational results will serve as constraints for the models. Further boundary conditions are given by the timing (feedback from project area A) and the chemical budget of late accretion.