1,2Zixian Shi, 1Zhensheng Wang, 1Renguang Zuo, 3,4Shijie Li, 2Yiheng Li, 2,5Razvan Caracas
Earth and Planetary Science Letters, 696, 120392 Link to Article [DOI: 10.1016/j.epsl.2026.120392]
1State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, 430074, China
2Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, 1, Rue Jussieu, Paris, 75005, France
3Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
4CAS Center for Excellence in Comparative Planetology, Hefei, China
5The Research Institute of the University of Bucharest (ICUB), University of Bucharest, Romania
Copyright Elsevier
The Moon-forming giant impact involved a collision between the proto-Earth and a planetary body named Theia. This resulted in the formation of a protolunar disk, where the Moon formed beyond the Roche limit, and the Earth accreted at the center. As the initial bodies are lost, reconstructing this event presents considerable challenges. Here, we place further constraints on the composition and structure of Theia by integrating improved impact numerical modeling with meteorite data. Our findings indicate that the core mass fraction (CMF) of Theia was below ∼6%, as higher values yield physically untenable mantle compositions and conflict with the Moon’s Fe-poor nature. Chemical composition constraints suggest that Theia’s mantle was composed of differentiated materials similar to aubrites, which may have derived predominantly from the mantle of a disintegrated inner Solar System planet analogous to proto-Mercury. The proto-Earth’s mantle exhibited a composition akin to that of the present-day Earth. Our research mitigates the isotope crisis in the Earth–Moon system and offers a pathway to probe Theia’s mantle mineralogy.
