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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.

The distribution of water in the Moon’s interior carries implications for the origin of the Moon 1 , the crystallization of the lunar magma ocean 2 and the duration of lunar volcanism 2 . 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 crystallization 4 , 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. Water abundance and hydrogen isotope compositions of two-billion-year-old basalt samples returned from the Moon by the Chang’e-5 mission suggest that the samples came from a relatively dry mantle source.

Deep-ocean O2 concentrations over the past 3.5 billion years are estimated using the oxidation state of iron in submarine basalts and indicate that deep-ocean oxygenation occurred in the Phanerozoic. Oxygen in the deep Oxygenation of the deep ocean associated with a rise in atmospheric oxygen levels in the geological past is thought to signal the emergence of modern marine biogeochemical cycles. Estimates of the timing of deep-ocean oxygenation and the related increase in atmospheric oxygen levels range from about 800 to 400 million years ago and are generally based on geochemical signatures that indirectly reflect the geochemical state of the deep ocean. This paper presents a more direct, quantitative constraint on the deep-ocean oxygen content from the Archaean to the Cenozoic based on the oxidation state of iron in submarine basalts. The authors suggest that deep-ocean oxygenation occurred in the Phanerozoic and probably not until the late Palaeozoic, less than 420 million years ago. The oxygenation of the deep ocean in the geological past has been associated with a rise in the partial pressure of atmospheric molecular oxygen (O 2 ) to near-present levels and the emergence of modern marine biogeochemical cycles 1 , 2 , 3 , 4 , 5 . It has also been linked to the origination and diversification of early animals 3 , 5 , 6 , 7 . It is generally thought that the deep ocean was largely anoxic from about 2,500 to 800 million years ago 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , with estimates of the occurrence of deep-ocean oxygenation and the linked increase in the partial pressure of atmospheric oxygen to levels sufficient for this oxygenation ranging from about 800 to 400 million years ago 3 , 5 , 7 , 11 , 13 . Deep-ocean dissolved oxygen concentrations over this interval are typically estimated using geochemical signatures preserved in ancient continental shelf or slope sediments, which only indirectly reflect the geochemical state of the deep ocean. Here we present a record that more directly reflects deep-ocean oxygen concentrations, based on the ratio of Fe 3+ to total Fe in hydrothermally altered basalts formed in ocean basins. Our data allow for quantitative estimates of deep-ocean dissolved oxygen concentrations from 3.5 billion years ago to 14 million years ago and suggest that deep-ocean oxygenation occurred in the Phanerozoic (541 million years ago to the present) and potentially not until the late Palaeozoic (less than 420 million years ago).

The lunar basalt samples returned by the Chang’e-5 mission erupted about 2.0 billion years ago during the late period of the Moon’s secular cooling. The conditions of mantle melting in the source region and the migration of magma through the thick lithosphere that led to this relatively late lunar volcanism remain open questions. Here we combine quantitative textural analyses of Chang’e-5 basaltic clasts, diffusion chronometry, clinopyroxene geothermobarometers and crystallization simulations to establish a holistic picture of the dynamic magmatic–thermal evolution of these young lunar basalts. We find that the Chang’e-5 basalts originated from an olivine-bearing pyroxenite mantle source (10–13 kbar or 250 ± 50 km; 1,350 ± 50 °C), similar to Apollo 12 low-Ti basalts. We propose these magmas then ascended through the plumbing system and accumulated mainly at the top of the lithospheric mantle (~2–5 kbar or 40–100 km, 1,150 ± 50 °C), where they stalled at least several hundred days and evolved via high-degree fractional crystallization. Finally, the remaining evolved melts erupted rapidly onto the surface over several days. Our magmatic–thermal evolution model indicates abundant low-solidus pyroxenites in the mantle source with a slightly enhanced inventory of radioactive elements can explain the prolonged, but declining, lunar volcanism up to about 2 billion years ago and beyond.The lunar basalts sampled by the Chang’e-5 mission originated from melting of a clinopyroxene-rich mantle source enhanced in radioactive elements, potentially explaining this late lunar volcanism, according to sample analysis and crystallization modelling.

Evaporation or freezing of water-rich fluids with dilute concentrations of dissolved salts can produce brines, as observed in closed basins on Earth 1 and detected by remote sensing on icy bodies in the outer Solar System 2 , 3 . The mineralogical evolution of these brines is well understood in regard to terrestrial environments 4 , but poorly constrained for extraterrestrial systems owing to a lack of direct sampling. Here we report the occurrence of salt minerals in samples of the asteroid (101955) Bennu returned by the OSIRIS-REx mission 5 . These include sodium-bearing phosphates and sodium-rich carbonates, sulfates, chlorides and fluorides formed during evaporation of a late-stage brine that existed early in the history of Bennu’s parent body. Discovery of diverse salts would not be possible without mission sample return and careful curation and storage, because these decompose with prolonged exposure to Earth’s atmosphere. Similar brines probably still occur in the interior of icy bodies Ceres and Enceladus, as indicated by spectra or measurement of sodium carbonate on the surface or in plumes 2 , 3 . Samples from the asteroid (101955) Bennu, returned by the OSIRIS-REx mission, include sodium-bearing phosphates and sodium-rich carbonates, sulfates, chlorides and fluorides formed during evaporation of a late-stage brine.

NASA’s Curiosity rover detected light-toned rocks along its traverse on Mars. Geochemical data suggest that the rocks represent a diversity of silica-rich magmatic rock types that may be analogous to Earth’s early continental crust. Understanding of the geologic evolution of Mars has been greatly improved by recent orbital 1 , 2 , 3 , in situ 4 , 5 and meteorite 6 , 7 , 8 data, but insights into the earliest period of Martian magmatism (4.1 to 3.7 billion years ago) remain scarce 9 . The landing site of NASA’s Curiosity rover, Gale crater, which formed 3.61 billion years ago 10 within older terrain 11 , provides a window into this earliest igneous history. Along its traverse, Curiosity has discovered light-toned rocks that contrast with basaltic samples found in younger regions 12 . Here we present geochemical data and images of 22 specimens analysed by Curiosity that demonstrate that these light-toned materials are feldspar-rich magmatic rocks. The rocks belong to two distinct geochemical types: alkaline compositions containing up to 67 wt% SiO 2 and 14 wt% total alkalis (Na 2 O + K 2 O) with fine-grained to porphyritic textures on the one hand, and coarser-grained textures consistent with quartz diorite and granodiorite on the other hand. Our analysis reveals unexpected magmatic diversity and the widespread presence of silica- and feldspar-rich materials in the vicinity of the landing site at Gale crater. Combined with the identification of feldspar-rich rocks elsewhere 9 , 13 , 14 and the low average density of the crust in the Martian southern hemisphere 15 , we conclude that silica-rich magmatic rocks may constitute a significant fraction of ancient Martian crust and may be analogous to the earliest continental crust on Earth.

It has been suggested that Saturn’s moon Enceladus possesses a subsurface ocean. The recent discovery of silica nanoparticles derived from Enceladus shows the presence of ongoing hydrothermal reactions in the interior. Here, we report results from detailed laboratory experiments to constrain the reaction conditions. To sustain the formation of silica nanoparticles, the composition of Enceladus’ core needs to be similar to that of carbonaceous chondrites. We show that the presence of hydrothermal reactions would be consistent with NH 3 - and CO 2 -rich plume compositions. We suggest that high reaction temperatures (>50 °C) are required to form silica nanoparticles whether Enceladus’ ocean is chemically open or closed to the icy crust. Such high temperatures imply either that Enceladus formed shortly after the formation of the solar system or that the current activity was triggered by a recent heating event. Under the required conditions, hydrogen production would proceed efficiently, which could provide chemical energy for chemoautotrophic life. Observations indicate that the southern hemisphere of Enceladus is geologically active, with spray containing Si nanoparticles being ejected from an underground ocean. Here, the authors report that experiments to constrain reaction conditions suggest the core is similar to that of carbonaceous chondrites.

Abiotic hydrocarbons and carboxylic acids are known to be formed on Earth, notably during the hydrothermal alteration of mantle rocks. Although the abiotic formation of amino acids has been predicted both from experimental studies and thermodynamic calculations, its occurrence has not been demonstrated in terrestrial settings. Here, using a multimodal approach that combines high-resolution imaging techniques, we obtain evidence for the occurrence of aromatic amino acids formed abiotically and subsequently preserved at depth beneath the Atlantis Massif (Mid-Atlantic Ridge). These aromatic amino acids may have been formed through Friedel–Crafts reactions catalysed by an iron-rich saponite clay during a late alteration stage of the massif serpentinites. Demonstrating the potential of fluid-rock interactions in the oceanic lithosphere to generate amino acids abiotically gives credence to the hydrothermal theory for the origin of life, and may shed light on ancient metabolisms and the functioning of the present-day deep biosphere. High-resolution imaging techniques show that aromatic amino acids such as tryptophan formed abiotically and were subsequently preserved at depth beneath the Atlantis Massif of the Mid-Atlantic Ridge, supporting the hydrothermal theory for the origin of life.

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.

Elevated H2O concentrations and oxygen fugacities are two fundamental properties that distinguish magmas formed in subduction zones from new crust generated at mid-ocean ridges. However, the mechanism of magma oxidation and how it relates to the increase in H2O remain unclear. In this study, we used infrared spectroscopy of mantle wedge orthopyroxene to trace the temporal and spatial evolution of oxygen fugacity during the transport of hydrous arc melts towards the crust. A positive correlation between equilibrium oxygen fugacity and orthopyroxene H2O concentrations for the peridotite samples studied allowed the assignment of specific, commonly observed absorption bands to redox-sensitive crystallographic defects. H2O content associated with these redox-sensitive defects increases in concentration across individual crystals, uniquely preserving the time-dependent transition from reduced to oxidized conditions during the migration of hydrous melts through the mantle wedge. A separate but related process of reaction with H2 occurring primarily during the earliest stages of melt–mantle reaction may be fundamental in generating the oxidized nature of hydrous melts. Our study proposes that the oxidized nature of arc magmas may not be a primary feature, but is instead acquired progressively as hydrous primary melts react with the surrounding mantle.