title: Neodymium isotope evidence for a chondritic composition of the Moon.
abstract: Samarium-neodymium isotope data for six lunar basalts show that the bulk Moon has a 142Nd/144Nd ratio that is indistinguishable from that of chondritic meteorites but is 20 parts per million less than most samples from Earth. The Sm/Nd formation interval of the lunar mantle from these data is 215(-21)(+23) million years after the onset of solar system condensation. Because both Earth and the Moon likely formed in the same region of the solar nebula, Earth should also have a chondritic bulk composition. In order to mass balance the Nd budget, these constraints require that a complementary reservoir with a lower 142Nd/144Nd value resides in Earth's mantle.
authors.affiliation: NASA Johnson Space Center, Mail Code KR, Houston, TX 77058, USA. kai.rankenburg1@jsc.nasa.gov
authors.forename: K
authors.initials: K
authors.lastname: Rankenburg
authors.forename: A D
authors.initials: AD
authors.lastname: Brandon
authors.forename: C R
authors.initials: CR
authors.lastname: Neal