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Isotopic constraints on the nature of Earth’s building blocks

Wednesday 12 May, 4 PM CET

Dr. Mario Fischer-Gödde

ABSTRACT: The presence of nucleosynthetic isotope heterogeneities among meteorites and the Earth enables to deduce information on the nature of the planetary building blocks that were added at different stages of accretion. Because the isotopic composition of the Earth’s mantle for many elements is similar to enstatite chondrites, this similarity was interpreted to reflect that the Earth during the second half of its main accretion primarily grew from volatile-poor enstatite chondrite-like building blocks originating from the inner solar system. Hence, water and other volatile elements must have been brought to the Earth during earlier accretion stages.
Volatile elements represent a crucial prerequisite for the birth and evolution of life on Earth. While it is largely accepted that the water of Earth’s oceans derives from the accretion of carbonaceous chondrite-like materials originating from the outer solar system, the timing of this accretion remains highly debated. New Ru isotope data for ultramafic Archean rocks from SW Greenland and Pilbara provide evidence that Earth acquired its volatile element budget during the latest stage of its growth, by late accretion of a volatile-rich late veneer.