Compositional Variability of 2.0‐Ga Lunar Basalts at the Chang'e‐5 Landing Site.

China's Chang'e‐5 (CE‐5) mission successfully returned a total of 1.731 kg of lunar material from the north‐eastern Oceanus Procellarum region. Young (∼2.0 Ga) ages were reported from the CE‐5 basalts. However, there are controversies on whether they are low‐Ti or high‐Ti mare basalt type. Here, we report the results of a comprehensive petrographic, elemental, and Pb isotopic investigation on a 17.6 mg CE‐5 basalt clast (CE5C0000YJYX048). By combining high‐resolution X‐ray tomography of the clast and microbeam (scanning electron microscope SEM, electron probe microanalyzer EPMA) analyses of mineral grains peeled off the clast surface, we derived the bulk clast chemical composition with a very small sample consumption (i.e., <3 mg). The poikilitic clast has a bulk TiO2 content of 3.78 ± 1.01 wt%, which is representative of a low‐Ti basalt end‐member in the lunar mare basalts samples. Furthermore, the pyroxene in the studied clast is dominantly pigeonite, in contrast to other reported CE‐5 samples where augite is the dominant pyroxene mineralogy. Despite these compositional peculiarities, in situ secondary ion mass spectrometer dating yielded a Pb‐Pb age of 2,040 ± 22 Ma for the fragment, which is consistent with ages reported from other CE‐5. Based on the chemical and age data analyzed in this study, it can be concluded that the lunar basalts obtained from the CE‐5 mission originated from a low‐Ti mare basalt‐type source. The mineral composition of the mare basalt clast studied, which is dominated by pigeonite, fayalite, and anorthite, likely resulted from late‐stage magmatic crystallization when the magma was enriched in Fe. Plain Language Summary: Studying lunar meteorites and samples returned from missions are key ways to conduct scientific research and increase our knowledge of the moon. These methods allow us to move beyond simple observations and make direct measurements of lunar materials. After 45 years from the Apollo and Luna missions, in December 2020, Chang'E‐5 (CE‐5), China's first lunar mission, returned with a total of 1.731 kg of lunar soil. The basalt clasts in the soil are dated at ∼2 billion years ago, which represents the youngest lunar basalt ever studied. The origin of the CE‐5 basalts is still debated because it is composed of heterogeneous materials. The CE‐5 basaltic clast studied here has a unique mineral composition compared to previous data of other CE‐5 basaltic clasts and Apollo basalt samples. This discrepancy is ascribed to the different stages of magma formation in which the occurrence of different minerals subtracted elements and changed the magma's composition. As a result, the heterogeneity of the CE‐5 returned lunar basalts relates to different stages of magma evolution. The present project adds new knowledge to understanding the formation of the lunar basalts around the CE‐5 landing site. Key Points: A new processing method of lunar rock clast is given to characterize the composition and age at milligram‐level sample consumptionAn independent high‐precision in situ secondary ion mass spectrometer Pb‐Pb age of 2,040 ± 22 Ma is determined for a basaltic clast from the Chang'e‐5 lunar missionThe basaltic clasts returned by Chang'e‐5 mission have remarkable compositional variability and are likely composed of low‐Ti mare basalt [ABSTRACT FROM AUTHOR]