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Mare volcanics on the Moon are the key record of thermo-chemical evolution throughout most of lunar history 1 – 3 . Young mare basalts—mainly distributed in a region rich in potassium, rare-earth elements and phosphorus (KREEP) in Oceanus Procellarum, called the Procellarum KREEP Terrane (PKT) 4 —were thought to be formed from KREEP-rich sources at depth 5 – 7 . However, this hypothesis has not been tested with young basalts from the PKT. Here we present a petrological and geochemical study of the basalt clasts from the PKT returned by the Chang’e-5 mission 8 . These two-billion-year-old basalts are the youngest lunar samples reported so far 9 . Bulk rock compositions have moderate titanium and high iron contents  with KREEP-like rare-earth-element and high thorium concentrations. However, strontium–neodymium isotopes indicate that these basalts were derived from a non-KREEP mantle source. To produce the high abundances of rare-earth elements and thorium, low-degree partial melting and extensive fractional crystallization are required. Our results indicate that the KREEP association may not be a prerequisite for young mare volcanism. Absolving the need to invoke heat-producing elements in their source implies a more sustained cooling history of the lunar interior to generate the Moon’s youngest melts. Isotopic analysis of basalt clasts returned from the Moon by the Chang’e-5 mission indicates that the rocks were derived from a mantle source that lacked potassium, rare-earth elements and phosphorus.

Knowledge regarding the abundance and distribution of solar wind (SW)‐sourced water (OH/H2O) on the Moon in the shallow subsurface remains limited. Here, we report the NanoSIMS measurements of H abundances and D/H ratios on soil grains from three deepest sections of the Chang'E‐5 drill core sampled at depths of 0.45–0.8 m. High water contents of 0.13–1.3 wt.% are present on approximately half of the grain surfaces (topmost ∼100 nm), comparable to the values of Chang'E‐5 scooped soils. The extremely low δD values (as low as −995‰) and negative correlations between δD and water contents indicate that SW implantation is an important source of water beneath the lunar surface. The results are indicative of homogeneous distribution of SW‐derived water in the vertical direction, providing compelling evidence for the well‐mixed nature of the lunar regolith. Moreover, the findings demonstrate that the shallow subsurface regolith of the Moon contains a considerable amount of water. Plain Language Summary Recently, China's Chang'E‐5 mission targeted a higher latitude on the Moon than previous Apollo and Luna missions, and brought back scooped and drilled samples to the Earth. These new soil samples provide an opportunity to investigate the distribution, abundance, and origin(s) of water in Moon's middle latitude. Here, we focus on using the NanoSIMS technique to analyze water content on soil near‐surface regions to understand whether the solar wind (SW)‐derived water could be preserved after burial at depth. Our results show that more than half of the core soils have high water contents on the rims of grains, similar to those of the Chang'E‐5 scooped soils. This finding suggests that the SW remains an important source of water in the Moon's subsurface. Our work provides direct evidence that the lunar regolith below the surface contains considerable water from SW implantation. This type of water could be a promising water resource in future exploration. Key Points More than half of the soils from the single drill core have high water contents and low D/H ratios below the surface The solar wind (SW)‐derived water could be preserved for hundreds of millions of years if buried at depth Lunar regolith from the drill core contains considerable water from SW implantation, which is much more accessible

The history of mare volcanism critically informs the thermal evolution of the Moon. However, young volcanic eruptions are poorly constrained by remote observations and limited samples, hindering an understanding of mare eruption flux over time. The Chang’e-5 mission returned the youngest lunar basalts thus far, offering a window into the Moon’s late-stage evolution. Here, we investigate the mineralogy and geochemistry of 42 olivine and pyroxene crystals from the Chang’e-5 basalts. We find that almost all of them are normally zoned, suggesting limited magma recharge or shallow-level assimilation. Most olivine grains record a short timescale of cooling. Thermal modeling used to estimate the thickness and volume of the volcanism sampled by Chang’e-5 reveals enhanced magmatic flux ~2 billion years ago, suggesting that while overall lunar volcanic activity may decrease over time, episodic eruptions at the final stage could exhibit above average eruptive fluxes, thus revising models of lunar thermal evolution. This work estimates the eruption volume of the young Chang’e-5 lunar samples using diffusion chronology and thermodynamic simulations, and finds that there was an increase in volcanic eruption flux about 2.0 billion years ago.

Lunar volcanism provides critical insights into the Moon's thermochemical evolution. We present petrological and geochemical analyses of six very‐low‐Ti (VLT) basalt fragments from Chang'e‐6 (CE6) samples. These basalts yield a Pb‐Pb age of around 2.9 Ga, representing the youngest reported VLT volcanism. They are slightly older than the low‐Ti basalts from the same soils and exhibit distinct pyroxene compositions and 238U/204Pb ratios, indicating derivation from distinct mantle sources. Compared to Apollo and Luna VLT basalts, these samples share similarly depleted Sr‐Pb isotopes but display elevated rare earth element concentrations and TiO2 contents. These basalts most likely derived from low‐degree melting of an olivine‐orthopyroxene source followed by 30%–40% fractional crystallization. Further diffusion chronometry reveals rapid magma ascent from magma chamber to surface, likely facilitated by the thin lunar crust resulting from the South Pole‐Aitken basin‐forming impact. Our results provide new insights into the petrogenesis of volcanic activity on the lunar farside.

The role of widespread ilmenite in lunar mare regions in the abundance and diurnal variations of surficial OH/H 2 O remains controversial. Here, we report the water content and hydrogen isotopes in the rims of lunar ilmenites from Chang’e-5 soil samples using an ion microprobe. Ilmenite rims exhibit higher water contents (~730 − 3,700 ppm) and lower δD values (−884 to −482‰) than that of the lunar mantle, indicating a predominantly endogenic origin from solar-wind (SW) implantation. Our data further reveal that although ilmenite and silicate minerals overlap in the δD vs. H 2 O diagram, almost all ilmenites fall above those of silicates with SW-like δD values. This signature is consistent with the drastic difference in vesicle abundance between ilmenite and silicate minerals. Thus, the lower water content in ilmenite rims most likely reflects a faster dynamic equilibrium between SW-hydrogen implantation and outgassing than in other silicates. These findings suggest that ilmenite may play a critical role in the surface water cycle of lunar maria within the Procellarum KREEP Terrane. This is also crucial for assessing the in-situ resource utilization potential of the region, highlighting the need to reevaluate ilmenite as a viable resource for future lunar exploration. The study shows that lunar ilmenite preserves less solar wind-generated water than silicate minerals, likely due to faster water escape. This finding suggests that ilmenite may critically influence surface water variations within the lunar Procellarum KREEP Terrane.

The oxygen fugacity ( f O 2 ) of the lunar mantle is of pivotal significance in comprehending the formation and evolution of the Moon. However, the f O 2 of the lunar farside mantle remains unknown due to the lack of samples returned from the farside. Here, we determine the oxygen fugacity of 23 basaltic fragments from the Chang’e-6 (CE6) soil, the first farside sample collected from the South Pole–Aitken (SPA) basin. The spinel V oxybarometer and pyroxene Eu oxybarometer yield an average f O 2 of ΔIW –1.93 ± 0.58 (2σ), indicating a more reduced state compared to the nearside Apollo and Chang’e-5 (CE5) basalts, which have an average f O 2 of ΔIW –0.80 ± 0.64 (2σ). Such asymmetry in oxygen fugacity of the lunar mantle can be attributed to two processes: nearside mantle oxidation by a larger amount of Fe sinking into the core triggered by asymmetric crystallisation of the lunar magma ocean, and/or farside mantle reduction caused by S 2 and CO degassing during the SPA massive impact. Nevertheless, the reduced nature of the underlying mantle beneath the SPA basin reveals another aspect of lunar asymmetry. This paper determines the oxygen fugacity of the Chang’e-6 basalts from the South Pole–Aitken (SPA) basin on the farside of the Moon. The results show that the mantle beneath the farside SPA basin is more reduced than that beneath the nearside, as determined by the Apollo and Chang’e-5 basalts.

Remote sensing data revealed that the presence of water (OH/H₂O) on the Moon is latitude-dependent and probably time-of-day variation, suggesting a solar wind (SW)-originated water with a high degassing loss rate on the lunar surface. However, it is unknown whether or not the SW-derived water in lunar soil grains can be preserved beneath the surface. We report ion microprobe analyses of hydrogen abundances, and deuterium/hydrogen ratios of the lunar soil grains returned by the Chang’e-5 mission from a higher latitude than previous missions. Most of the grain rims (topmost ~100 nm) show high abundances of hydrogen (1,116 to 2,516 ppm) with extremely low δD values (−908 to −992‰), implying nearly exclusively a SW origin. The hydrogen-content depth distribution in the grain rims is phase-dependent, either bell-shaped for glass or monotonic decrease for mineral grains. This reveals the dynamic equilibrium between implantation and outgassing of SW-hydrogen in soil grains on the lunar surface. Heating experiments on a subset of the grains further demonstrate that the SW-implanted hydrogen could be preserved after burial. By comparing with the Apollo data, both observations and simulations provide constraints on the governing role of temperature (latitude) on hydrogen implantation/migration in lunar soils. We predict an even higher abundance of hydrogen in the grain rims in the lunar polar regions (average ~9,500 ppm), which corresponds to an estimation of the bulk water content of ~560 ppm in the polar soils assuming the same grain size distribution as Apollo soils, consistent with the orbit remote sensing result.