Geochemical aspects of accretion Aryavart Anand Institute of

Geochemical aspects of accretion Aryavart Anand Institute of Geological Sciences University of Bern, Switzerland 1

Initial Composition of the Protoplanetary Disk Metbase. org Taylor 2001, Solar System Evolution Geochemical aspects of accretion - A. Anand 2

1) The composition of the Earth shows marked differences to the primordial material The major differences lie in the relative abundances of the volatile elements. 2) Homogeneous accretion vs. Heterogeneous accretion. 3) Earth cannot be the product of accretion of a single kind of material. Earth has an end member composition for certain element abundances and isotope compositions (e. g. , Dauphas et al. , 2004; Fischer-G¨odde et al. , 2015, Mezger et al. , 2020). 4) Bulk composition of the Earth multiple components with distinct chemical and isotopic compositions their accretion must follow a specific sequence. Geochemical aspects of accretion - A. Anand 3

Mezger et al. (2021) CI and Sc normalized 1) Chondritic abundances for the refractory elements and a depletion trend for the volatile elements. 2) The depletion of the siderophile elements is attributed to the segregation of the metallic core and the depletion of the chalcophile elements to the segregation of a sulfide melt (hadean matte). Condensation temperature 50% Tc (K) Geochemical aspects of accretion - A. Anand 4

CI and Sc normalized Mezger et al. (2021) Condensation temperature 50% Tc (K) Geochemical aspects of accretion - A. Anand 5

CI and Sc normalized Mezger et al. (2021) Condensation temperature 50% Tc (K) Geochemical aspects of accretion - A. Anand 6

Mezger et al. (2021) Geochemical aspects of accretion - A. Anand 7

The origin of water Component A Component B Component C Highly reduced Strongly oxidized CM like material 2% water Metallic iron can not coexist with hydroxides in mineral phases. Its volatile content is currently unconstrained. Earth has 0. 1 -0. 3% water Insignificant in terms of volume to account for the total water content of Earth. Geochemical aspects of accretion - A. Anand 8

Conclusions Mezger et al. (2021) Geochemical aspects of accretion - A. Anand 9