Low Ni and Co olivine in Chang'E-5 basalts reveals the origin of the young volcanism on the Moon.

Mare basalts returned by the Chang'E-5 (CE5) mission extend the duration of lunar volcanism almost one billion years longer than previously dated. Recent studies demonstrated that the young volcanism was related neither to radiogenic heating nor to hydrous melting. These findings beg the question of how the young lunar volcanism happened. Here we perform high-precision minor element analyses of olivine in the CE5 basalts, focusing on Ni and Co. Our results reveal that the CE5 basalt olivines have overall lower Ni and Co than those in the Apollo low-Ti basalts. The distinctive olivine chemistry with recently reported bulk-rock chemistry carries evidence for more late-stage clinopyroxene-ilmenite cumulates of the lunar magma ocean (LMO) in the CE5 mantle source. The involvement of these Fe-rich cumulates could lower the mantle melting temperature and produce low MgO magma, inhibiting Ni and Co partitioning into the magma during lunar mantle melting and forming low Ni and Co olivines for the CE5 basalts. Moreover, the CE5 olivines show a continuous decrease of Ni and Co with crystallization proceeding. Fractional crystallization modeling indicates that Co decreasing with crystallization resulted from CaO and TiO2 enrichment (with MgO and SiO2 depletion) in the CE5 primary magma. This further supports the significant contribution of late-stage LMO cumulates to the CE5 volcanic formation. We suggest that adding easily melted LMO components resulting in mantle melting point depression is a key pathway for driving prolonged lunar volcanism. This study highlights the usefulness of olivine for investigating magmatic processes on the Moon.

Su B ，Zhang D ，Chen Y ，Yang W ，Mao Q ，Li XH ，Wu FY ... -  《-》

Fusible mantle cumulates trigger young mare volcanism on the cooling Moon.

Su B ，Yuan J ，Chen Y ，Yang W ，Mitchell RN ，Hui H ，Wang H ，Tian H ，Li XH ，Wu FY ... -  《Science Advances》

A dry lunar mantle reservoir for young mare basalts of Chang'e-5.

The distribution of water in the Moon's interior carries implications for the origin of the Moon1, the crystallization of the lunar magma ocean2 and the duration of lunar volcanism2. The Chang'e-5 mission returned some of the youngest mare basalt samples reported so far, dated at 2.0 billion years ago (Ga)3, from the northwestern Procellarum KREEP Terrane, providing a probe into the spatiotemporal evolution of lunar water. Here we report the water abundances and hydrogen isotope compositions of apatite and ilmenite-hosted melt inclusions from the Chang'e-5 basalts. We derive a maximum water abundance of 283 ± 22 μg g-1 and a deuterium/hydrogen ratio of (1.06 ± 0.25) × 10-4 for the parent magma. Accounting for low-degree partial melting of the depleted mantle followed by extensive magma fractional crystallization4, we estimate a maximum mantle water abundance of 1-5 μg g-1, suggesting that the Moon's youngest volcanism was not driven by abundant water in its mantle source. Such a modest water content for the Chang'e-5 basalt mantle source region is at the low end of the range estimated from mare basalts that erupted from around 4.0 Ga to 2.8 Ga (refs. 5,6), suggesting that the mantle source of the Chang'e-5 basalts had become dehydrated by 2.0 Ga through previous melt extraction from the Procellarum KREEP Terrane mantle during prolonged volcanic activity.

Hu S ，He H ，Ji J ，Lin Y ，Hui H ，Anand M ，Tartèse R ，Yan Y ，Hao J ，Li R ，Gu L ，Guo Q ，He H ，Ouyang Z ... -  《-》

Two-billion-year-old volcanism on the Moon from Chang'e-5 basalts.

The Moon has a magmatic and thermal history that is distinct from that of the terrestrial planets1. Radioisotope dating of lunar samples suggests that most lunar basaltic magmatism ceased by around 2.9-2.8 billion years ago (Ga)2,3, although younger basalts between 3 Ga and 1 Ga have been suggested by crater-counting chronology, which has large uncertainties owing to the lack of returned samples for calibration4,5. Here we report a precise lead-lead age of 2,030 ± 4 million years ago for basalt clasts returned by the Chang'e-5 mission, and a 238U/204Pb ratio (µ value)6 of about 680 for a source that evolved through two stages of differentiation. This is the youngest crystallization age reported so far for lunar basalts by radiometric dating, extending the duration of lunar volcanism by approximately 800-900 million years. The µ value of the Chang'e-5 basalt mantle source is within the range of low-titanium and high-titanium basalts from Apollo sites (µ value of about 300-1,000), but notably lower than those of potassium, rare-earth elements and phosphorus (KREEP) and high-aluminium basalts7 (µ value of about 2,600-3,700), indicating that the Chang'e-5 basalts were produced by melting of a KREEP-poor source. This age provides a pivotal calibration point for crater-counting chronology in the inner Solar System and provides insight on the volcanic and thermal history of the Moon.

Li QL ，Zhou Q ，Liu Y ，Xiao Z ，Lin Y ，Li JH ，Ma HX ，Tang GQ ，Guo S ，Tang X ，Yuan JY ，Li J ，Wu FY ，Ouyang Z ，Li C ，Li XH ... -  《-》

Surges in volcanic activity on the Moon about two billion years ago.

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.

Tian HC ，Zhang C ，Yang W ，Du J ，Chen Y ，Xiao Z ，Mitchell RN ，Hui H ，Changela HG ，Zhang TX ，Tang X ，Zhang D ，Lin Y ，Li X ，Wu F ... -  《Nature Communications》