Geocheminar spring-2017
High-silica Hadean crust
May 15, 2017,
noon - 1 p.m.
3853 Slichter
Presented By:
Patrick Boehnke
University of Chicago
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. Analyzing the 87Sr/86Sr ratio of apatite inclusions in Archean zircons from Nuvvuagittuq, Canada, using the unique CHILI instrument shows that its protolith had formed a high (>1) Rb/Sr ratio reservoir by ~4.4 Ga. This result implies that the early crust had a broad range of igneous rocks, extending from mafic to highly silicic compositions.