Report

Oxygen isotopic evidence for vigorous mixing during the Moon-forming giant impact

Science  29 Jan 2016:
Vol. 351, Issue 6272, pp. 493-496
DOI: 10.1126/science.aad0525

You are currently viewing the abstract.

View Full Text

Rehomogenizing the Earth-Moon system

A giant impact formed the Moon, and lunar rocks provide insight into that process. Young et al. found that rocks on Earth and the Moon have identical oxygen isotopes. This suggests that well-mixed material from the giant impact must have formed both the Moon and Earth's mantle. The finding also constrains the composition of the “late veneer”: material sprinkled onto Earth after the Moon-forming impact.

Science, this issue p. 493

Abstract

Earth and the Moon are shown here to have indistinguishable oxygen isotope ratios, with a difference in Δ′17O of −1 ± 5 parts per million (2 standard error). On the basis of these data and our new planet formation simulations that include a realistic model for primordial oxygen isotopic reservoirs, our results favor vigorous mixing during the giant impact and therefore a high-energy, high-angular-momentum impact. The results indicate that the late veneer impactors had an average Δ′17O within approximately 1 per mil of the terrestrial value, limiting possible sources for this late addition of mass to the Earth-Moon system.

View Full Text