^1,2Yun Jiang et al. (>10)
The Astrophysical Journal Letters 945, L26 Open Access Link to Article [DOI 10.3847/2041-8213/acbd31]
¹CAS Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, People’s Republic of China
²Center for Excellence in Comparative Planetology, Chinese Academy of Sciences, Hefei 230026, People’s Republic of China

The Chang’E 5 (CE-5) samples represent the youngest mare basalt ever known and provide an access into the late lunar evolution. Recent studies have revealed that CE-5 basalts are the most evolved lunar basalts, yet controversy remains over the nature of their mantle sources. Here we combine Fe and Mg isotope analyses with a comprehensive study of petrology and mineralogy on two CE-5 basalt clasts. These two clasts have a very low Mg# (∼29) and show similar Mg isotope compositions to Apollo low-Ti mare basalts as well as intermediate TiO2 and Fe isotope compositions between low-Ti and high-Ti mare basalts. Fractional crystallization or evaporation during impact cannot produce such geochemical signatures that otherwise indicate a hybrid mantle source that incorporates both early- and late-stage lunar magma ocean (LMO) cumulates. Such a hybrid mantle source would be also compatible with the KREEP-like Rare Earth Elements pattern of CE-5 basalts. Overall, our new Fe–Mg isotope data highlight the role of late LMO cumulate for the generation of young lunar volcanism.