^1,2,3Yong Wang et al. (>10)
Earth and Planetary Science Letters 681, 119952 Link to Article [https://doi.org/10.1016/j.epsl.2026.119952]
¹State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
²YU-CUGW Joint Research Center on Deep Earth and Surface Dynamic Coupling, College of Resources and Environment, Yangtze University, Wuhan 430100, China
³College of Earth and Planetary Science, University of Chinese Academy of Sciences, Beijing 100049, China
Copyright Elsevier

The origin of lunar water—whether inherited during its formation (endogenous) or delivered later (exogenous)—remains a fundamental question in planetary science. Previous studies relying on hydrous minerals or melt inclusions are often compromised by post-magmatic processes. Zircon, with robust physico-chemical stability, serves as a superior archive for preserving primary magmatic composition. Here, we report the first SIMS measurements of water content and hydrogen isotopes in a ca.∼4.38 Ga zircon from lunar meteorite NWA 10049. The zircon exhibits a distinct core-rim structure with anomalous H2O-δD compositions: while the core maintains relatively homogeneous water content (735 to 1164 μg/g) with elevated δD (+1320 to +1882‰), the rim displays variable and inversely correlated water content (879 to 4268 μg/g) and δD (+1879 to +250‰). Such H2O-δD systematics—combined with geochemical and petrological signatures—precludes magmatic degassing or post-magmatic alteration. Instead, we attribute these variations to magma mixing and the subsequent assimilation of heterogeneous exogenous hydrous materials within a massive impact melt sheet. Our findings provide key evidence for the accretion of meteoritic material into the lunar interior before 4.38 Ga, which delivered substantial amounts of water and likely played a critical role in shaping the composition and spatial distribution of volatiles in the early Moon.