Early formation of the Moon 4.51 billion years ago

Melanie Barboni; Patrick Boehnke; Brenhin Keller; Issaku E Kohl; Blair Schoene; Edward D Young; Kevin D McKeegan

doi:10.1126/sciadv.1602365

Early formation of the Moon 4.51 billion years ago

Sci Adv. 2017 Jan 11;3(1):e1602365. doi: 10.1126/sciadv.1602365. eCollection 2017 Jan.

Authors

Melanie Barboni¹, Patrick Boehnke², Brenhin Keller³, Issaku E Kohl¹, Blair Schoene⁴, Edward D Young¹, Kevin D McKeegan¹

Affiliations

¹ Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, Los Angeles, CA 90095, USA.
² Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, Los Angeles, CA 90095, USA.; Department of the Geophysical Sciences, The University of Chicago, Chicago, IL 60637, USA.
³ Department of Geosciences, Princeton University, Princeton, NJ 08544, USA.; Berkeley Geochronology Center, Berkeley, CA 94709, USA.
⁴ Department of Geosciences, Princeton University, Princeton, NJ 08544, USA.

Abstract

Establishing the age of the Moon is critical to understanding solar system evolution and the formation of rocky planets, including Earth. However, despite its importance, the age of the Moon has never been accurately determined. We present uranium-lead dating of Apollo 14 zircon fragments that yield highly precise, concordant ages, demonstrating that they are robust against postcrystallization isotopic disturbances. Hafnium isotopic analyses of the same fragments show extremely low initial ¹⁷⁶Hf/¹⁷⁷Hf ratios corrected for cosmic ray exposure that are near the solar system initial value. Our data indicate differentiation of the lunar crust by 4.51 billion years, indicating the formation of the Moon within the first ~60 million years after the birth of the solar system.

Keywords: Age of the moon; Apollo zircons; early earth; early solar system evolution; giant impact; lunar magma ocean; planetary accretion.