  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 basalt, 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 with 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 which 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 REE 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.
