Lunar zircon from the Chang’e-5 landing site

Zircon is one of the most important U-bearing minerals in the lunar geochronological studies. Since the first lunar zircon grains were analyzed in the early 1980’s, the majority of lunar zircon U(Pb)-Pb ages obtained from the Apollo missions in the last decades were distributed between about 4.4 and 3.9 Ga. Although the crystallization age of Chang’e-5 (CE-5) basalts were obtained from baddeleyite, zirconolite and tranquillityite, we attempted to search for lunar zircon grains from the collected CE-5 lunar sample for comparison with the previous studies. We scanned almost all polished sections of the CE-5 powder sample to identify lunar zircon grains, most of which are isolated grains or mineral clast in agglutinates and impact melt breccias. In our study, only one zircon grain was preserved in the lithic clast of CE-5 basalts after the scanning of hundreds polished sections. This zircon records a precise Pb-Pb isochron age of 2036 ± 19 Ma, which is the youngest crystallization age ever reported for lunar zircon geochronology. Combined with the petrology, mineralogy and geochronology, we have demonstrated that this zircon grain is the extreme fractional product from a non-KREEP mantle source similar to CE-5 basalt. Compared to the zircon from Apollo mission, the sampling site of CE-5 provides a new case that lunar zircon can crystallize from a variety of magmatic compositions in addition to KREEP-related magma. In the future, we plan to perform the studies of zircon grains from CE-5 samples in different lithologies and try to find the origin of these zircons grains.