Nucleosynthetic zinc isotope anomalies reveal a dual origin of terrestrial volatiles
Theodor Steller, Christoph Burkhardt, Chun Yang, T. Kleine
Abstract
Determining the provenance of volatile elements in Earth is key for understanding the processes that led to its formation as a habitable planet. We show that the moderately volatile element zinc exhibits an isotopic dichotomy between non‑carbonaceous and carbonaceous meteorites, which presumably derive from the inner and outer Solar System, respectively. Terrestrial zinc has an intermediate isotopic composition, demonstrating that Earth accreted about 70% of its zinc from inner Solar System bodies. Using literature data, we find the same proportions for the more volatile elements hydrogen and nitrogen, suggesting Earth's volatile elements predominantly derive from inner Solar System objects and not, as often assumed, from the outer Solar System. Thus, Earth may have evolved to a habitable planet even without the contributions it received from the outer Solar System.