Abstract Mercury is one of the few terrestrial planets in the solar system with a magnetic field, yet the energy source to power its core dynamo remains unclear to date. Si, C, and possibly H are the top candidate light elements for its liquid core. Here, we showed experimentally that Si, C, and H in Fe‐Si‐C and Fe‐Si‐C‐H liquids share a simultaneous solubility at 9–21 GPa, 1,400°C–2,200°C, and this solubility decreases with decreasing temperature. When exceeding the simultaneous solubility, light elements will exsolve from the Fe melt as elemental phases such as diamond, graphite, silicon, and H2. We infer that if Mercury had an early liquid core primarily composed of saturated Fe‐Si‐C‐(H) liquid, subsequent cooling would lead to continuous light element exsolution in its liquid core. The gravitational potential released by the exsolved light elements can drive the compositional convection and power its long‐term core dynamo.

Pyroxene is a primary constituent mineral in basaltic lunar regolith. These minerals form through the cooling and crystallization of lunar basaltic magma and are subsequently altered by impact events. Thus, pyroxene can serve as a significant indicator for interpreting lunar magmatic processes and impact phenomena. For lunar samples that are mostly mafic and frequently shocked to various degrees, deciphering the effect of shock on pyroxene is necessary for a better understanding of the primary magmatic processes. However, previous studies have neglected to investigate the impact metamorphism of pyroxene in lunar regolith and the potential compositional changes that may result from such impacts. Lunar regolith samples returned by the Chang'E-5 (CE-5) mission are reworked from a monolithic mafic protolith with well-constrained compositions and record strong to mild shock effects that are widespread in the samples. The returned samples provide an excellent chance to distinguish the signatures of impact processes from magmatic activities. Here we report microstructural and compositional variations in a shocked pyroxene within a basaltic clast from CE-5 lunar regolith, which were analyzed by Raman spectroscopy, analytical scanning electron microscopy, electron probe microanalysis, and scanning transmission electron microscopy. The shock microstructures are characterized by the glide system of dislocation [001](100), pigeonite formation induced by shock-related deformations, and solid-melt partitioning and localized frictional melting at grain boundaries or within pyroxene. Combined with the occurrence of shock twins in ilmenite adjacent to the shock melt vein, these shock phenomena are approximately indicative of low-to-moderate shock pressure (9-17 GPa). Most parts of the pyroxene have abnormal Raman peaks at similar to 822 cm-1, suggesting the substitution of Si4+ by Al3+ in the tetrahedral site of this shocked pyroxene structure, and this characteristic is recognized as a shock indicator. Evidence from the morphology and elemental distribution of pigeonite within host augite suggests that the Si-Al substitution is consistent with the pigeonite formation, which is triggered or modified by shock-induced deformations and local frictional melting under the fast shear stress. The multiple trends of composition evolution in this single shocked pyroxene reflect sequential processes of magma crystallization, shock-related exsolution, and frictional melting. Our findings indicate that shock effects in pyroxene under low-to-moderate shock conditions can induce changes in composition and structure, and may obscure the evidence of magmatic evolution in pyroxene.

CM chondrites contain valuable insights into the formation and evolution of the solar nebula, as well as the secondary aqueous alteration processes that affected their parent bodies. Our study focuses on primary and secondary sulfides within the Aguas Zarcas (CM2) chondrite, investigating their formation mechanisms based on their morphology, textures, and compositions. Moreover, we infer the formation temperatures of the sulfides from 230 to 500 ℃ for primary and from 100 to 135 ℃ for secondary. We select representative grains and conduct Fe isotope measurements on them. The primary sulfides with δ56/54Fe ranging from − 2.44‰ to + 0.69‰ are associated with sulfide–silicate melt segregation, while secondary sulfides with δ56/54Fe values between − 1.83‰ and − 0.14‰ are linked to aqueous alteration. Overall, the Ni content of the grains is positively correlated with δ56/54Fe. It might be related to the changes in crystal structure and chemical bond lengths due to the increase in nickel content. Fe isotopes provide a new perspective on sulfide formation and the evolution of a carbonaceous chondrite parent body.

The Moon is strongly depleted in volatile elements and exhibits heavier isotopic signatures (e.g., K, Zn) than the Earth. However, the pronounced nearside-farside dichotomy and uneven distribution of volatiles across lunar interior raise the question of whether such heavier isotopic signatures resulted from a global giant impact or local magmatic processes. Here we report high sulfur contents (1800 ± 400 µg/g) and δ34S values (0.83 ± 0.16‰, 2SE, n = 17) in Chang'e-6 basalt from lunar farside, with similar δ34S values in two nonmare crustal clasts. These values fall within the range reported for nearside mare basalts and basaltic meteorites of different ages and mantle sources, indicating a broadly homogeneous δ34S composition across lunar interior that is ~2‰ heavier than the Earth's mantle. This isotopic signature cannot be explained by core formation or late accretion and is best attributed to global volatile loss during the Moon-forming impact. Subsequent magma ocean evolution and mantle overturn drove heterogeneous volatile budget in lunar mantle.

Previous high-temperature-pressure experiments predicted metallic iron's potential presence in the deep mantle below 250 km, arising from ferrous disproportionation in silicates, which could profoundly impact the redox environment and physicochemical properties. However, direct natural petrological evidence has been lacking, except scant clues like Fe-alloy inclusions in ultradeep diamonds. Here we present peridotite fragments, found in Cenozoic basalts from eastern China, containing decomposed Na-rich majoritic garnets (from depths of 410-550 km) and olivine with Fe0-spinel-bearing inclusions, likely originated from retrograded wadsleyite/ringwoodite. Enriched Zn-Sr isotopic compositions of the decomposed garnet indicate an origin associated with the stagnant Pacific slab in the mantle transition zone. Disproportionation of iron is evidenced by widely distributed submicron-sized spherical Fe-Ni alloys and Fe3+-rich (Fe3+/ΣFe = 0.35-0.40) olivine. These findings provide compelling evidence for recycling of stagnant slab components in the eastern Asia big mantle wedge (BMW), and iron disproportionation in the deep mantle.

0 INTRODUCTION Changbaishan volcanism,located on the border of China and North Korea,has been a subject of extensive research due to its unique geological features and active volcanic history(Wan et al.,2024).Two primary models have been proposed to explain the origin of Changbais-han volcanism(CV).

Mantle properties and metasomatic processes, together with interlayer interactions, in orogenic belts are still under debate. Post-collisional magmatic rocks could provide secondhand constraints on these issues. We have conducted an integrated geochronological, geochemical and isotopic study on post-collisional Zhanwa dolerites, the Dashui granodiorite-monzonite-monzogabbro complex and the Jiuzigou pyroxenite-syenite complex at West Qinling. The Zhanwa dolerites, being tholeiitic with flat trace element patterns, were mixtures of melts from asthenospheric and oceanic slab-fluid-metasomatized lithospheric mantle. The Dashui monzonite-monzogabbro suite is ultrapotassic with strongly right-inclined trace element patterns and evolved isotopic composition with (Sr-87/Sr-86)(i) = 0.7066-0.7068, epsilon(Nd)(t) = -4.56 to -4.35, epsilon(Hf)(t) = -3.14 to -2.35 and (Pb-206/Pb-204)(i) = 17.99-18.12. It was derived from melting of a mantle source metasomatized by continent-crustal materials. In contrast, the Dashui granodiorites are shoshonitic-calc-alkaline with more evolved isotopic compositions with (Sr-87/Sr-86)(i), epsilon(Nd)(t), epsilon(Hf)(t), and (Pb-206/Pb-204)(i) of 0.7074-0.7091, -7.56 to -5.51, -5.61 to -3.53 and 18.18-18.46, respectively. They represent hybrids of mantle-derived K-rich and crustal-derived felsic melts. The Jiuzigou complex has extremely high trace element contents. Its mantle source was metasomatized by both oceanic crustal fluids and sedimentary melts. Generation of these rocks (c. 235-223 Ma) not only recorded multiple mantle metasomatism, but also captured collective asthenospheric and lithospheric magmatic responses in a post-collisional setting.

The Chang'e-6 (CE-6) mission returned the first-ever soil samples from a farside mare basalt unit within the Apollo basin, the largest impact feature of the South Pole-Aitken (SPA) basin. Here, we integrated petrological and geochemical analyses on this soil and its main components to estimate the compositions of local mare basalt and nonmare components. The landing site basalt is a typical low-Ti basalt with low Mg# (30-31) and low contents of Th (1 ppm) and other incompatible elements. The bulk soil overall shows homogeneous major and trace elemental compositions, which are very different from the local basalt. Combined with petrological constraints, such differences reveal an incorporation of-40 +/- 5 wt% of noritic crust ejecta and 2-3 wt% meteoritic materials, without mantle-rock fragments. The mean composition of nonmare materials corresponds to anorthositic norite or norite (-60 +/- 5 vol% plagioclase) and is broadly comparable with Northwest Africa (NWA) 2995 clan meteorites and the prediction from remote sensing data for the SPA basin. The low-Th contents of the basalt, soil, breccia, and impact glasses (1-2 ppm) support negligible Th-rich components in ejecta materials and the underlying mantle and crust. These ground-truth results suggest the dominant distribution of intermediate FeO, mafic crust rocks on the Apollo basin floor, providing insights into the composition of the farside crust within the SPA basin.

The upper continental crust is isotopically enriched in heavy stable zirconium (Zr) isotopes compared to the mantle, indicating significant Zr isotope fractionation during crustal differentiation, though the mechanisms remain elusive. Here, we present zircon in-situ Zr isotope data for two magmatic suites of distinct origins (the 91-88 Ma Lilong Complex and the 83-74 Ma Wolong granites) from the Gangdese arc lower crust in southern Tibet. The Lilong Complex, comprising garnet gabbro, quartz diorite, and tonalite, represents a continuous differentiation sequence of arc magma, whereas the Wolong granites were derived from partial melting of the migmatitic garnet gabbro in the Lilong Complex. Zircon from both suites exhibit consistent core-to-rim increases in 594/90Zr values, coupled with the negative correlation between 594/90Zr and Zr/Hf ratios, indicating that zircon preferentially incorporates light Zr isotopes during crystallization. In the Lilong Complex, zircon 594/90Zr increases with rising whole-rock SiO2, suggesting gradual enrichment of heavy Zr isotopes during arc magma differentiation. Rayleigh modeling indicates that zircon crystallization primarily controls the Zr isotopic evolution of melts. The Wolong granites have higher zircon 594/90Zr than their garnet gabbro source, reflecting Zr isotope fractionation between melt and residue during partial melting. These observations indicate that enrichment in the heavy Zr isotopes in felsic magmas results from both fractional crystallization of isotopically light zircon and retention of light Zr isotopes in restites during partial melting. Our findings highlight the roles of magmatic differentiation and crustal reworking in arc settings in shaping the Zr isotopic composition of the continental crust.

The understanding of storage conditions and evolution processes of igneous rocks is pivotal in unraveling the architecture and dynamics of trans-crustal magmatic systems. Here we combine amphibole major and trace elements compositions, geothermobarometers and chemometry and published whole-rock compositions of the Paleocene-Eocene (65-40 Ma) Gangdese batholith from longitude 85 degrees E to 95 degrees E to discuss the nature and formation processes of the batholith, explore the across sectional structure of the large-scale paleo-continental magmatic arc batholith, and reveal the resultant implications for crustal formation and evolution. The pressure results suggest that most of the exposed 65-40 Ma Gangdese batholith was emplaced at 1-8 kbar, corresponding to the middle to upper crust. Specifically, these exposed intrusions were predominantly emplaced at 2-4 kbar, with deeper denudation observed toward the eastern part of the Gangdese arc. The calculated melts in equilibrium with amphiboles are more silicic (mainly rhyolitic) than their host rocks (dioritic to granodioritic), yet share similar geochemical features with those of the coeval Gangdese high-Si granites and Linzizong high-Si rhyolites. This feature suggests that the granitoid batholiths represent crystal mushes that experienced varying degrees of partial melt loss prior to solidification, and high-Si magmas are residual silicic melts extracted from the batholitic magma mushes. The geochemical evolutionary trend of the 65-40 Ma Gangdese batholith parallels the 1-8 kbar isobaric and polybaric experimental liquid lines of descent of hydrous basaltic magmas. The wholerock geochemical data suggest that most mafic samples of the Gangdese batholith are not primitive basaltic magmas, but rather underwent fractional crystallization at depth prior to emplacement. Some samples even contain minor amphiboles cores derived from magma reservoirs in the deep crust. These observations indicate that most of magmas were mainly mantle-derived and evolved through polybaric crystallization processes. The shallower granitoid batholiths could represent frozen fossilized magma mushes, intricately linked with shallow volcanic eruptions, magmatic processes in the deep crust, or even melting in the mantle source. Despite crustal rock remelting and magma mixing can occur during batholith formation, polybaric differentiation processes in trans-crustal magmatic columns, saturating with distinct mineral assemblages at different depths, crucially shapes the chemically stratified continental crust.

The distribution of Oligo−Miocene magmatic rocks from southern Tibet in space and time yields critical information on the geometry and deformation of the subducted Indian lithosphere which impacts on plateau growth following the India and Eurasia collision. A growing body of geophysical evidence has shown that the subducted Indian lithosphere beneath the Tibetan Plateau has been torn apart. However, the spatiotemporal distribution and cause of the tearing remain enigmatic. Timing of the post-collisional magmatic rocks in southern Tibet exhibits four patterns of decreasing ages; magmatism began earlier in the west and east Himalayan syntaxis and evolved to two age undulations in the central southern Tibet. Seismic images show that regions of slab window (both 90°E and 84°E) and flattened subducted lithosphere (both 86°E and 81°E) are present at depth of 135 km. Correspondingly, increasing mineral crystallization temperatures (absolute value of 50 °C) were recorded in the Oligo−Miocene ultrapotassic-potassic rocks at 90°E and 84°E, while opposing trends were shown by coeval ultrapotassic-potassic rocks at 86°E and 81°E. Besides, the melting depth of the Oligo−Miocene ultrapotassic-potassic primitive melts decreases from nearly 100 km to 70 km between 81°E and 90°E, probably indicating progressive rising of the lithosphere-asthenosphere boundary. Such variations were possibly the results of the focused flow and upwelling of asthenosphere, which advanced rapidly but diachronously through weakened and torn sectors within the overlying Indian slab. The upwellings probably induced diachronously upward bending of the residual Indian slab and its flattening, which accelerated the tearing of the Indian lithosphere during continental subduction.

Minerals with compositional zoning in volcanic products are widely used to decipher the history of magmatic evolution. However, structural information, which reflects physical conditions and crystallization equilibrium, has often been overlooked. This study presents the first report on the structural zoning of deep-derived biotite phenocrysts through investigations of metaluminous rhyolite from Long Valley, CA. Biotite is enriched in Si, Mg, and K and depleted in Fe3+, Ti, and Al-IV in core zones compared with rims. In situ structural analyses, including micro X-ray diffraction, Raman spectroscopy, and transmission electron microscopy, were conducted to identify cores with perfect 2M(1) polytype and disordered rims of biotite. The results demonstrate the effectiveness of these methods in revealing various (micro)polytypes of a single species, which occur at different crystallization temperatures, pressures, supersaturation levels, and oxygen fugacities. The concept of structural zoning is introduced here to describe the different structural features distributed systematically in various parts of minerals. By combining structural and chemical zoning, we illustrate a two-step growth for samples: equilibrium crystallization of the highly ordered cores in a deep magma reservoir with high temperature and pressure, followed by rapid growth of disordered rims during magma mixing in a crystal mush. We further discuss the implications of these findings for reflecting the plumbing system structure and eruption history of rhyolitic magma over extended periods. Our study underscores the remarkable sensitivity of structural zoning in delineating the crystallization conditions of minerals and documenting the environmental changes within magma.

The formation of magma reservoir and resultant construction of large batholith are increasingly recognized as long-term incremental processes. Here we employed back-scattered electron and cathodoluminescence images, in-situ major and trace elements, and Sr isotopes of plagioclase for five lithological groups from the Quxu complex batholith (south Tibet), which shed new light on the nature and incremental construction processes of batholith. Our results show that plagioclases display diverse textures and show systematic differences in geochemistry and Sr isotopes for different lithologies, indicating that their host rocks originated from multiple magma sources and/or underwent distinct magmatic processes. Plagioclases in Group I granodiorites and Group III mafic dykes and mafic magmatic enclaves exhibit comparable textural features (e.g., resorption and sieved textures) and share similar Sr (< 1500 ppm) and Ba (< 200 ppm) contents, and Sr-87/Sr-86 ratios (I-Sr) (0.7035-0.7050) at given lower An (20-50) values, suggesting that they were evolved from similar mafic magma sources. The significant variations in An (20-90), Sr and Ba contents of plagioclase in Group III indicate both fractional crystallization and magma mixing. Plagioclases in Group II monzogranites have a similar An ranges to Group I but higher Sr (900-2200 ppm) contents and I-Sr (mostly 0.7045 to 0.7066) values, suggesting that they formed from partial melting of juvenile mafic crust without significant mantle contribution. Plagioclases in Group IV granodiorites and Group V monzogranites exhibit higher Sr (500-3000 ppm) contents than other groups at given An values. Their I-Sr values fall within the range of Group II, indicating a similar magma source. Abundant plagioclases displaying normal and oscillatory zonings in them implies that fractional crystallization occurred, while the presence of typical glomerocrysts in Group V indicates mush disaggregation. The simulation results of the trace elements indicate that the different lithologies of the Quxu batholith represent different states of magma reservoirs, corresponding to crystal mushes with varying degrees of extracted melts. The incremental growth processes of lager batholith operate as an open system, in which magma convection, mixing and recharge, crystal accumulation, recycling and reaction with melts, and mush disaggregation commonly occur.

Early Triassic granitoids are widespread in the northwestern West Qinling Orogen, China, but their petrogenesis and geodynamic implications remain unclear. In this study, we integrated new field and petrological observations, mineralogical compositions, zircon U-Pb dating, Hf isotopic and whole-rock geochemical analyses for the early Triassic granitic pluton in the Daheba area to determine its magma source and geodynamic scenario. The pluton is composed of granodiorite and syenogranite and carries microgranular enclaves (MEs) which formed at ca. 253-249 Ma. The granitoids show wide SiO2 contents of 63.73-77.49 wt% (av. 69.89), high K2O contents of 3.4-5.4 wt% (av. 4.1) and moderate Mg# of 16-51 (av. 36), belonging to high-K, calc-alkaline I-type granites. These rocks have high radiogenic but uniform Hf isotopic compositions with 176Hf/177Hf and epsilon Hf(t) of 0.282511-0.282658 and -3.85 - +1.25, respectively. The MEs hosed within the granite are characterized by high Mg# of 35-58 (av. 46) and variable epsilon Hf(t) of -4.64 - +9.35, which likely represent a hybridized melt derived from a slab-modified mantle and lower crust. In combination with coeval magmatic rocks in the western Gonghe-East Kunlun area, we propose a genetic model where mafic magmas derived from an enriched mantle and underplated beneath the overlying lower crust are considered to have produced the high-K felsic magma. Further, the hybridized melt ascended to shallower crustal levels to generate a series of rocks ranging from dioritic MEs to granodiorite to syenogranite. Mass balances modeling suggests that the generation of these rocks involved 36 % of the lower crustal-derived melt and 64 % of the SCLM (R2 = 0.9). Our new data, in tandem with published results suggest that the Daheba pluton formed during the subduction stage of the Paleo-Tethyan Ocean and that a local extensional episode occurred at 253-249 Ma in the western Gonghe area.

Sulfides are accessory phases in lunar rocks but are important for understanding lunar interior processes as well as impacts on the lunar surface. Whether or not the lunar mantle had achieved sulfide saturation during magma ocean evolution and displays homogeneous sulfur isotopes remains under debate. The Chang'e-5 (CE-5) mission returned young (2.0 Ga) basalts from a mare terrain in the northern Oceanus Procellarum. Here we study chemical and sulfur isotopic compositions (delta(SV)-S-34-CDT) of sulfides from CE-5 basaltic fragments and combine them with delta S-34 of other young (3.1-3.0 Ga) lunar low-Ti basalt (NWA 10597 and NWA 4734) and gabbro meteorites (NWA 6950) to compare them with Apollo low-Ti and high-Ti mare basalts. The sulfides in basaltic fragments of CE-5 are troilites (FeS) with low abundances of Ni, Co, and Cu (e.g., Ni < 0.04 wt% and Ni/Co < 0.3). Textures and chemical compositions indicate that most troilites are late-stage crystallization products from the highly evolved CE-5 basalts. Several troilites occur in the matrices of impactite clasts and are intergrown with Fe-Ni metal (12-36 wt% Ni, Ni/Co of 12-39). These troilites are distinct from the major population of troilites with noticeably higher Ni abundances (mostly > 0.2 wt% with Ni/Co of 1-3) and reconcile with the addition of meteoritic materials into the impact melts. The delta(SV)-S-34-CDT of large troilite grains (>10 mu m) from the CE-5 basaltic fragments and lunar meteorites were obtained by high-precision, high-spatial-resolution femtosecond laser ablation MC-ICP-MS which achieved external uncertainty (0.65 %o, 2SD at 8-mu m laser spots) like nano-SIMS. Sulfur degassing during surficial effusive lava flow likely led to a slight decrease in delta S-34 (by similar to 1 %o) for some basaltic fragments; however, such effects were limited to the scale of bulk rock samples, consistent with previous results. The mean delta 34S of troilites in CE-5 basaltic fragments (0.35 +/- 0.25 %o, 2SE, n = 45) is similar to those of ancient (3.8-3.1 Ga old) Apollo low-Ti and high-Ti mare basalts and the young gabbro cumulate NWA 6950 (0.56 +/- 0.21 %o, 2SE, n _ 10). The paired NWA 10597 and NWA 4734 show consistent delta S-34, lower than most values by - 0.5 %o. Current data thus indicate that most mantle sources of lunar basalts would be homogeneous for delta S-34 (0.6 +/- 0.3 %o) and minor regions may be different. The overall homogenous delta S-34 from different mantle sources with variably low sulfur contents supports sulfide-undersaturated accumulation of the lunar magma ocean, which was inherited from strong volatile loss and evaporative fractionation during the formation of the Moon.

The origin of the K-feldspar megacrysts is still controversial and how magmas move in crystal-rich reservoir and the mechanism of the reactivation of crystal mushes after rheological locking are still elusive. K-feldspar megacryst in granitoids is a good candidate to constrain these issues. We carried out an integrated study of field geology, crystal size distribution (CSD), LA-ICP-MS zircon U-Pb geochronology, whole-rock geochemistry, and in-situ major and trace elements and Pb isotopic compositions of K-feldspar megacrysts from the monzogranites and mafic microgranular enclaves (MMEs) of the Quxu batholith in the Gangdese belt, southern Tibet. The Quxu monzogranites have a magma crystallization age of similar to 50 Ma. Some elements (e.g., Al, Sr, Cr and Ni) of the Quxu monzogranite and MMEs show scatter and no linear variations with increasing SiO2, indicating that simple magma mixing between mafic and felsic endmembers is unconspicuous for the formation of the Quxu monzogranites. The K-feldspar megacrysts from the Quxu monzogranites and MMEs can be divided into three types: normal zoning, reverse zoning and oscillatory zoning or no zoning. In-situ major and trace element of the Kfeldspar megacrysts, combined with their variation in-situ Pb isotopic composition (Pb-206/Pb-204 = 18.41-18.80, Pb-207/Pb-204 = 15.42-15.75 and Pb-208/Pb-204 = 38.29-39.06), indicate that the Quxu monzogranites were formed by the assembly of multiple heterogeneous magma pulses. The CSD results suggest that K-feldspar megacrysts have a longer residence time of 0.14-0.33 k.yr to 4.1-52 k.yr. We suggest that K-feldspar megacrysts could grow prolongedly via crystals transfer or magma injection of different batches in melt-present environments, and magma mush in cold-stored could be rejuvenated by the repeatedly recharging of hot magma pulses.

Young lunar mare basalts are recent volcanic products distributed mainly in the Procellarum-KREEP-Terrane. However, these young basalts were never investigated in situ until 2013 by Chang'e-3, and then sampled by Chang'e-5 in 2020. Using the returned Chang'e-5 samples as ground truth, and examining Moon Mineralogy Mapper data globally, we found the young basalts containing less abundant olivine (< 10%) than previously suggested. The Chang'e-3 and Chang'e-5 basalts belong to a type of underrepresented basalt. We reassessed the model ages of the young basalts using the new chronology function calibrated by the Chang'e-5 samples and found the young basalts have a trend of increasing TiO2 abundance with time. The young basalts with an age of around 2.0 Ga (billion years ago) are widespread in the Procellarum-KREEP-Terrane, including the Chang'e-5 unit. This indicates mare volcanism was still active at that time and an additional heat source or mechanism may be needed compared to older basalts. Young mare samples from Chang'e-5 and other potential sites are needed to constrain the late lunar thermal and volcanic history.

Supplemental Data S1: Major and trace elements and age data summary of the studied Oligocene-Miocene magmatic rocks. Supplemental Data S2: Zircon trace elements of the studied Oligocene-Miocene magmatic rocks. Table S1: Zircon U-Pb ages of the studied Oligocene-Miocene magmatic rocks. Table S2: Clinopyroxene major elements of the studied Miocene ultrapotassic-potassic volcanic rocks. Table S3: Published ages of the Oligocene to Miocene magmatic rocks in southern Tibet. Table S4: Calculated primary magmas and pressure estimates of the ultrapotassic rocks in southern Tibet.

Lunar mare basalts provide a probe to study the magmatic and thermal evolution of the Moon. The Chang'e-5 (CE-5) mission returned samples from a young and hitherto unsampled mare terrain, providing fresh opportunities to understand lunar volcanic history. A detailed petrologic survey was conducted in this study on basalt fragments and glasses from the returned CE-5 soil samples. Relatively large-sized (100-400 mu m) basaltic fragments were hand-picked and examined for texture, mineral assemblage and mineral chemistries. Basaltic fragments exhibit dominantly subophitic textures and are phenocryst-free, with low to intermediate-Ti (2.1-5.5 wt%) and low Mg# (Mg/(Mg + Fe) x 100, 19-47, with an average whole-rock Mg# of 33) consistent with olivine-melt equilibrium calculation (Mg# = 34). A range of highly evolved basaltic materials have been identified, in which abundant fayalitic olivine, symplectitic intergrowths, and Si + K-rich mesostasis co-exist were found resulting from late-stage silicate liquid immiscibility. Basaltic glass compositions largely overlap with basaltic fragment compositions suggesting they are locally derived. The CE-5 basalts have a relatively limited range of eruption temperatures of 1150-1230. C. Based on their petrographic and geochemical characteristics, some CE-5 mare basalts are highly evolved and some of the resultant basaltic melt products underwent high crystallization. Thermodynamic modeling using MELTS suggests highly evolved basaltic magma was produced by a low-pressure and simple fractional crystallization under reduced conditions. This may have occurred at the surface in the inflated Em4/P58 flow with a thickness of similar to 50 m. The low degree of partial melting mantle source of the parental melts is the late-stage lunar magma ocean cumulates in a similar manner to some evolved low-Ti mare basalt meteorites, although the source of CE-5 basalts may have been slightly more Ti-rich.