Highly Siderophile Element Constraints on Accretion and Differentiation of the Earth-Moon System
2007
Day, James M.D. | Pearson, D Graham | Taylor, Lawrence A.
A new combined rhenium-osmium- and platinum-group element data set for basalts from the Moon establishes that the basalts have uniformly low abundances of highly siderophile elements. The data set indicates a lunar mantle with long-term, chondritic, highly siderophile element ratios, but with absolute abundances that are over 20 times lower than those in Earth's mantle. The results are consistent with silicate-metal equilibrium during a giant impact and core formation in both bodies, followed by post-core-formation late accretion that replenished their mantles with highly siderophile elements. The lunar mantle experienced late accretion that was similar in composition to that of Earth but volumetrically less than (~0.02% lunar mass) and terminated earlier than for Earth.
显示更多 [+] 显示较少 [-]