Understanding Hadean (> 4 Ga) Earth requires knowledge of its crust. The composition of the crust and volatiles migrating through it directly influence the makeup of the atmosphere, the composition of seawater, and nutrient availability. Despite its importance, there is little known and less agreed upon regarding the nature of the Hadean crust. By analyzing the 87Sr/86 Sr ratio of apatite inclusions in Archean zircons from Nuvvuagittuq, Canada, we show that its protolith had formed a high (> 1) Rb/Sr ratio reservoir by at least 4.2 Ga. This result implies that the early crust had a broad range of igneous rocks, extending from mafic to highly silicic compositions.
Boehnke, P., Bell, E.A., Stephan, T., Trappitsch, R., and Keller, C.B., Pardo, O.S., Davis, A.M., Harrison, T.M, and Pellin, M.J. (2018). Potassic, high-silica Hadean crust. Proceedings of the National Academy of Sciences 115 (25) 6353-6356.