EARLY EARTH · Early Earth evolution: chemical differentiation vs. mantle mixing

Although short-lived chronometers have yielded a precise chronology of the Early Earth differentiation, there is insufficient data available on the chemical fractionation related to these processes to model the Early Earth’s differentiation. 142Nd isotope data suggest that a reservoir enriched in rare earth elements (REE) has existed since 4.53 Ga, but has not been sampled since its formation. A key question is whether such a reservoir could remain hidden for more than 4.5 Gyr in the convective mantle. The first goal of this project is to test whether the REE alternatively could be stored in the core. Information on the mantle composition and the extent of chemical differentiation in the Early Earth will be also obtained by measurement of Sm-Nd, Pt-Re-Os and Lu-Hf radiogenic systems of Archean samples. This work will provide valuable information on (1) the redox state of the Early Earth, (2) the nature of the precursor material forming the Earth, the chronology of Earth's differentiation relative to the Moon formation, and (4) for reconstructing a model for terrestrial magma ocean crystallization. This proposal will provide the possibility of tackling a topic from a number of angles, using new instrumentation. New approaches and collaborations will be combined in order to constrain the most realistic model of the early Earth evolution.