^1,2Jinting Kang, ¹Zhengyu Hou, ¹Haochen Yang, ¹Xue Tang, ^2,3Weibiao Hsu, ^1,2Fang Huang
Journal of Geophysical Research: Planets, 131, e2026JE009894
Link to Article [DOI: 10.1029/2026JE009894]
¹State Key Laboratory of Lithospheric and Environmental Coevolution, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China
²Deep Space Exploration Laboratory, Hefei, China
³Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, China

Published by arrangement with John Wiley & Sons

Magma oceans represent a pivotal stage in the early evolution of terrestrial planets. Early-formed asteroids, driven by the decay of ²⁶Al, may have also experienced such magma ocean processes. To investigate potential magma ocean differentiation on asteroid 4 asteroids, we reported high-precision iron isotope data for 25 eucrites and 13 diogenites. Eucrites exhibit a δ⁵⁶Fe range of approximately 0.1‰, varying from −0.044 to 0.073‰, with a mean value of 0.020 ± 0.013‰ (2SE, N = 25). Diogenites display δ⁵⁶Fe ranging from −0.051 to 0.018‰, yielding an average of −0.004 ± 0.011‰ (2SE, N = 13). The observed Fe isotope variation and offset between eucrites and diogenites cannot be produced by terrestrial weathering, impacts, and core formation. Combined with MELTS modeling using two different initial compositions for Vesta, the isotope variation can be explained by magma ocean differentiation. A cross-planetary comparison is made with the Moon, where magma ocean differentiation and associated Fe isotope variations have been extensively studied. Vestan samples exhibit remarkably limited δ⁵⁶Fe variation (∼0.1‰) compared to lunar basalts (∼0.3‰). This dichotomy may reflect distinct magma ocean evolution pathways across planetary bodies: later pyroxene crystallization, the absence of ilmenite-driven mantle overturn, and rapid cooling in the case of Vesta. Thus, planetary geochemical diversity is fundamentally shaped by magma ocean dynamics modulated by body size, composition, and thermal history.

¹Heng-Ci Tian, ¹Wei Yang, ²Huijuan Zhang, ¹Jingyan Cai, ¹Yangting Lin, ³Keqing Zong, ⁴Qi Liu, ⁵Feixiang Liu, ⁶Caihong Gao, ⁷Maoyong He
Journal of Geophysical Research: Planets, 131, e2026JE010077 Link to Article [DOI: 10.1029/2026JE010077]
¹Key Laboratory of Planetary Science and Frontier Technology, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
²East China University of Technology, Nanchang, China
³State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan, China
⁴State Key Laboratory of Critical Mineral Research and Exploration, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
⁵School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
⁶Research Center for Planetary Science, College of Earth Sciences, Chengdu University of Technology, Chengdu, China
⁷State Key Laboratory of Loess Science, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, China

Published by arrangement with John Wiley & Sons

To further constrain the lunar Li isotopic composition and its behavior during lunar magmatic differentiation, we measured twelve lunar meteorites, including mare basalts, Mg-suite rocks and anorthosites. Petrographic observation, dilute acid cleaning, and trace elemental characteristics indicate minimal terrestrial contamination. Low-Ti basalt meteorites yield a restricted δ⁷Li range (2.75 ± 0.52‰ to 3.95 ± 0.16‰), consistent with Apollo low-Ti basalts (3.1∼5.6‰). The Mg-rich norite Arguin 002 shows a similar value, supporting limited Li isotope fractionation during early lunar magma ocean (LMO) differentiation, a conclusion corroborated by modeling results of Li isotopic evolution during LMO differentiation. The heavier δ⁷Li in high-Ti basalts, however, points to the presence of interaction between ilmenite-bearing cumulate-derived melts and the ambient mantle rather than to simple late-stage LMO differentiation. Combining the reported Apollo and La Paz mare basalt meteorites data, we estimate the lunar mantle δ⁷Li to be 3.8 ± 1.3‰, indistinguishable from the Earth’s mantle, implying negligible fractionation during the Giant Impact. In contrast, lunar anorthosites exhibit extreme δ⁷Li variations (−0.7‰ to 9.8‰) with a negative correlation with Li content, likely reflecting impact-driven secondary redistribution. These findings not only confirm the Earth-Moon Li isotopic similarity using meteorites from diverse lunar terrains that complement the Apollo collection but also reveal that the lunar crust has been pervasively modified by impact processes, which have significantly disturbed its primary Li isotopic compositions.

¹Hyunseob Baik, ²Eun-Jin Cho, ¹Kwang-Eun Kim
Icarus (in Press)
Open Access Link to Article [DOI: 10.1016/j.icarus.2026.117341]
¹Resources Exploration & Development Research Division, Korea Institute of Geosciences and Mineral Resources (KIGAM), Daejeon, Republic of Korea
²Division of Space Exploration, Korea Astronomy and Space Science Institute (KASI), Daejeon, Republic of Korea

Copyright Elsevier

The Moon Mineralogy Mapper (M³) acquired 85-band hyperspectral data (430–3000 nm) at 140 m/pixel resolution between 2008 and 2009 for spectral imaging of the lunar surface. Conventional per-pixel methods, such as the Modified Gaussian Model (MGM) and Integrated Band Depth (IBD), have been widely used for lunar mineral detection but address complementary problems and do not provide sub-pixel abundance estimates across entire scenes. In this study, linear spectral unmixing (LSU) with Iterative Error Analysis (IEA) endmember extraction was applied to M³ Level 2 reflectance data for sub-pixel mineral mapping of Theophilus crater. After noise reduction via Minimum Noise Fraction (MNF) and enhancement of absorption features through continuum removal, IEA extracted five image-derived endmembers without prior mineralogical information or reference libraries. The extracted endmembers were subsequently identified against 23 reference spectra from the RELAB and USGS spectral libraries using explicit criteria based on diagnostic absorption-band positions and Pearson correlation (r = 0.87–0.97 for the assigned minerals). Four endmembers were identified as spinel, plagioclase, pyroxene, and OH/H₂O-bearing materials, while the fifth remains unassigned and likely reflects space-weathering effects or mosaicking artifacts. The five-endmember model reconstructs the observed continuum-removed spectra with a mean RMSE of 0.010, and the derived relative abundance maps show a reasonable spatial correspondence with independent Kaguya Multiband Imager mineral maps (Spearman ρ up to 0.63). The resulting maps show spinel concentrated at the central peak, plagioclase dominating the peak and crater walls, and broadly distributed pyroxene, consistent with previous studies. Notably, the unmixing results reveal spatially distinct abundance maxima for spinel and plagioclase within the central peak, suggesting sub-kilometer compositional gradients within the Pink Spinel Anorthosite (PSA) lithology. This sub-pixel approach yields fractional abundance maps that complement conventional per-pixel methods. The combination of library-independent endmember extraction and library-based identification demonstrates that LSU with IEA provides an effective sub-pixel mapping framework for lunar regions where prior mineralogical knowledge is limited.

^1,2Angel Mojarro, ²José C. Aponte, ²Daniel P. Glavin, ²Jamie E. Elsila, ^1,2Jason P. Dworkin, ^3,4,5Harold C. Connolly Jr.
Geochimica et Cosmochimica Acta (in Press)
Open Access
Link to Article [DOI: 10.1016/j.gca.2026.10.003]
¹University of Maryland Baltimore County and Center for Research and Exploration in Space Science and Technology, NASA GSFC, Greenbelt, MD, USA
²Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
³Department of Geology, School of Earth and Environment, Rowan University, Glassboro, New Jersey, USA
⁴Department of Earth and Planetary Sciences, American Museum of Natural History, New York, New York, USA
⁵Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA

Copyright Elsevier

The return of pristine samples from carbonaceous asteroids Ryugu by JAXA’s Hayabusa2 mission and Bennu by NASA’s OSIRIS-REx mission has enabled the direct comparative study of prebiotic organic compounds across the two primitive bodies. Using pyrolysis, thermochemolysis, and one-pot derivatization coupled to gas chromatography-triple quadrupole-mass spectrometry, we analyzed free volatile, insoluble, and soluble organic matter in a Ryugu aggregate and compared results to a Bennu aggregate and stones of interest. Pyrolysis of the Ryugu sample revealed polycyclic aromatic hydrocarbons, their alkylated homologues, and sulfur-, oxygen-, and nitrogen-bearing heterocyclic aromatic compounds consistent with aqueous alteration of the parent body. One-pot derivatization of the Ryugu aggregate yielded only tentative detections of β-alanine and 2,4-diaminopyrimidine. This is in contrast to the 14 proteinogenic α-amino acids and five canonical nucleobases previously detected across Bennu samples using the same technique. Thermochemolysis of the Ryugu sample revealed limited methylated derivatives while Bennu samples did not yield compounds above the procedural blank. The sparse thermochemolysis detections in samples from both asteroids are notable given that diverse methylated derivatives have been reported from the Orguiel (CI1) and Murchison (CM2) meteorites. We interpret these results as most likely originating from reagent-mineral interactions suppressing TMAH yields. Overall, contrasting organic inventories reflect divergent-parent body histories. Results from the Ryugu samples are consistent with a CI1-like classification, displaying increased alkylation of insoluble organic matter alongside depleted soluble organic matter abundances. In contrast, Bennu preserves heterogeneous organic signatures across stones recording multiple distinct alteration episodes. The presence of prebiotic molecules including amino acids and nucleobases across both asteroids further highlights the significance of carbonaceous bodies in contributing the chemical building blocks of life throughout the early Solar System.

¹Yang Bai et al. (>10)
Geochimica et Cosmochimica Acta (in Press) Link to Article [DOI: 10.1016/j.gca.2026.09.038]
¹State Key Laboratory of Continental Evolution and Early Life, NWU-HKU Joint Center of Earth and Planetary Sciences, Department of Geology, Northwest University, Xi’an 710069, China

Copyright Elsevier

The composition of the lunar deep interior remains debated, as remote sensing observations indicate that impact-excavated materials from within and around large basins contain both olivine and low-Ca pyroxene (LCP). Here we show a partially melted exotic troctolitic clast from Chang’e-5 lunar soils that records impact-induced mineral transformations. The exotic clast consists of forsteritic olivine grains with magnesium-rich rims and pyroxene crystals embedded in a feldspathic glassy matrix. Pyroxene crystals occur as elongated aggregates, with dendritic crystallites growing along the grain edges. The elongated pyroxene crystals show distinct zoning, with Fe-enriched, low-Ca cores and Al-enriched, high-Ca rims, while the dendritic crystallites are compositionally identical to the rims. Elemental mass-balance considerations suggest that impact-induced melting and recrystallization of olivine and anorthite generated the observed LCP–Al-rich high-Ca pyroxene (HCP) assemblage, with Si released during anorthite transformation compensating for the substantial Si consumption during LCP formation. These observations indicate that the LCP formed through impact-induced partial melting of an olivine-rich troctolite under rapid cooling conditions, rather than being a primary phase excavated from the lunar deep interior. Our findings demonstrate that LCP signatures observed around large impact basins, e.g., Imbrium and South Pole-Aitken basins, may originate from impact-modified olivine-rich lithologies, rather than being directly excavated from the deep interior. These results raise the possibility that such transformations may be a widespread process associated with large-scale impacts on the Moon and have important implications for the interpretation of remote sensing data and constraints on the composition of the lunar interior.

^1,2Alan E. Rubin
Meteoritics & Planetary Science (in Press)
Open Access Link to Article [DOI: 10.1111/maps.70244]
¹Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California, USA
²Maine Mineral & Gem Museum, Bethel, Maine, USA

Published by arrangement with John Wiley & Sons

Major chondrite groups (H, L, LL, R, EH, EL, CK) with some members of petrologic type 5 and 6 also have some members of types 3 and 4; they do not have members of type 1 or 2. Their parent bodies had onion-shell structures and were internally heated by the decay of ²⁶Al. These bodies experienced significant thermal metamorphism but only minor aqueous alteration. Major chondrite groups (CI, CM, CV, CR) that have at least some members of petrologic type 1 or 2 have no members of petrologic type 5 or 6. Their parent bodies were subjected to extensive aqueous alteration but little thermal metamorphism. As shown previously, there is a positive correlation between petrologic type and shock stage in ordinary chondrites. Their parent bodies were disrupted and reassembled while still hot; subsequent stochastic collisions caused the exposed hotter materials (i.e., outcrops of higher petrologic types) to develop more-intense shock features. Although CK chondrites encompass the entire range of metamorphic petrologic types (3–6), they exhibit no correlation between petrologic type and shock stage. This may indicate the CK parent body was relatively small, cooled quickly, and was disrupted and reassembled into a rubble pile after it had already cooled down. Stochastic collisions into surface regions that had already cooled down would have resulted in every CK petrologic type developing about the same mean shock stage.

¹Eunjin Cho (>10)
Journal of Geophysical Research: Planets, 131, e2026JE009905
Open Access Link to Article [DOI: 10.1029/2026JE009905]
¹Korea Astronomy and Space Science Institute, Daejeon, Republic of Korea

Published by arrangement with John Wiley & Sons

The lunar surface is heterogeneous in grain size and metallic iron abundance due to diverse histories of space weathering. The spectral and polarimetric properties of the lunar regolith are strongly affected by both grain size and metallic iron particles. However, because physical and chemical alteration processes are closely coupled in their effects on optical properties, their combined influence remains poorly constrained. In this study, lunar simulants (JSC-1A and KLS-1) were sieved into two bulk-type and three size-separated fractions, and hydrogen reduction was conducted to produce metallic iron particles on grain surfaces. The spectral and polarimetric properties of these samples were then systematically measured. After reduction, reflectance decreases while the degree of positive polarization increases, consistent with Umov’s law. In addition, reflectance contrasts among grain sizes are reduced because fine grains preferentially darken, whereas the polarization–albedo relation remains sensitive to grain size. The reflectance of bulk-type fractions is intermediate, unlike that of natural bulk lunar soils, which resembles the finest fractions. In contrast, the polarization–albedo behavior of bulk-type fractions is close to that of the finest fraction. These differences from natural lunar soils suggest that agglutinates, which are absent in our reduced samples, may be important for the optical properties of natural bulk lunar soils. Further comparisons using natural lunar soils will help clarify the relative roles of agglutinates and grain-surface weathering products in controlling the optical properties of lunar regolith.

¹Fabrice Gaillard, ²Luiz Pereira, ¹Laurent Arbaret, ¹Giada Iacono-Marziano, ¹Emmanuel Le Trong, ^1,3Fabien Bernadou, ⁴Yves Marrocchi
Science, 394, 97–101 Link to Article [DOI: 10.1126/science.aef2542]
¹Institut des Sciences de la Terre d’Orléans, CNRS/Université d’Orléans/BRGM, Orléans, France
²GEOLAB, Hangzhou International Innovation Institute, Beihang University, Hangzhou, China
³CNRS, Géosciences Environnement Toulouse (GET), Observatoire Midi-Pyrénées, Toulouse, France
⁴Université de Lorraine, CNRS, CRPG, Nancy, France

Peprinted with permission from AAAS

Atmophile elements (carbon, hydrogen, and nitrogen) were thought to accrete late during planetary formation, yet cosmochemical and astrophysical evidence suggests that they were already present while small bodies, such as Vesta, were forming. High-temperature magmatic events on small bodies, however, should have outgassed these ultravolatile elements because gravity would have been insufficient to retain them. In this study, experiments reveal that gas bubbles strongly attach to metal droplets in magma ocean–like mixtures, forming compounds that resist segregation. Early flotation of such compounds would have enhanced mantle siderophile endowment, eliminating the need for late accretion. On small bodies, low gravity would have enabled millimeter- to centimeter-sized compounds to sink, trapping atmophiles in their interiors. This mechanism links core formation to the early entrapment of atmophile elements and provides a framework for reconciling volatile delivery across planetary bodies and planetary accretion models.

¹Jun Sakuma, ^2,3Hisashi Asanuma, ²Naoto Takahata, ^4,5Akira Yamaguchi, ¹Tsuyoshi Iizuka
American Mineralogist, 111, 1683–1692
Link to Article [https://msaweb.org/MSA/AmMin/TOC/2026/Abstracts/AM111P1683.pdf]
¹Department of Earth and Planetary Science, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
²Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-0882, Japan
³Graduate School of Human and Environmental Studies, Kyoto University, Sakyo, Kyoto 606-8501, Japan
⁴National Institute of Polar Research, Tokyo 190-8518, Japan
⁵Department of Polar Science, School of Multidisciplinary Science, SOKENDAI, Tokyo 190-8518, Japan

Copyright: The Mineralogical Society of America

Precise and accurate ages of asteroidal crusts are fundamental for reconstructing the timeline of magmatic, metamorphic, and impact events in the early Solar System. Zirconolite (CaZrTi2O7) is an accessory mineral found in a wide range of crustal rocks on both the Earth and Moon and has proven to be a potentially useful U-Pb chronometer. However, this mineral is rare in asteroidal meteorites, and its use for early Solar System chronology has been limited.

We present the in situ occurrence, U-Pb chronology, and chemistry of zirconolite in the andesitic meteorite Erg Chech 002, which represents a sample of the oldest known asteroidal crust. Zirconolite occurs as needle- and fiber-shaped and stubby crystals with widths of ∼3 μm and lengths up to ∼30 μm. Electron and ion microprobe analyses yielded concordant U-Pb data with a weighted mean 207Pb/206Pb age of 4557.9 ± 4.3 Ma (2σ), rendering it the Solar System’s oldest known zirconolite. Yet, this age is distinctly younger than reported high-precision 207Pb/206Pb ages varying from 4565.6 to 4566.2 Ma, which were obtained by acid leaching of pyroxene and whole-rock samples of the meteorite.

From its mineralogical and REE–(U Th)–(Nb Ta) characteristics, we argue that the zirconolite age represents the timing of a shock metamorphism of the parent asteroid’s crust. Our results suggest that 207Pb/206Pb dating for acid-leached samples can be affected by including even a tiny amount of metamorphic zirconolite, calling for caution in interpreting the high-precision 207Pb/206Pb age data. On the basis of thermodynamic and geochemical considerations, we infer further occurrences of zirconolite in alkali-silica-rich asteroidal rocks that rapidly cooled from high temperatures.

^1,2Xiaorong Qin, ^1,3,4Jianxi Zhu, ^1,3,4Hongping He, ⁵Yiliang Li
American Mineralogist, 111, 1537–1546
Link to Article [https://msaweb.org/MSA/AmMin/TOC/2026/Abstracts/AM111P1537.pdf]
¹State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
²National Key Laboratory of Deep Space Exploration/School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
³Center for Advanced Planetary Science (CAPS), Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
⁴University of Chinese Academy of Sciences, Beijing 100049, China
⁵Department of Earth & Planetary Sciences, the University of Hong Kong, Hong Kong 999077, China
Copyright: The Mineralogical Society of America

In Gale crater, the Curiosity rover has documented a sequence of ∼3500 million year old sedimentary rocks containing smectite, indicating the presence of liquid water. However, the paleoenvironment in Gale crater, particularly the question of whether a paleolake ever existed, remains hotly debated.

Here, we compare the interlayer cations of smectite from terrestrial basalt weathering sequences and marine environments. Marine smectites are considered key analogs for smectites detected in martian paleolakes due to perceived similarities in formation processes and geochemical contexts between terrestrial marine settings and ancient lacustrine environments on Mars. Numerous observations show that K/Na-rich smectite is associated with marine environments, whereas Ca2-rich smectite is typical of terrestrial basalt weathering sequences.

We find that the basal spacings of K- and Na-smectite are ∼10.0 Å, whereas the basal spacings of Ca2- and Mg2-smectite range from 13.1 to 13.8 Å at a relative humidity (<1%) equivalent to that of the Curiosity rover on Mars. The XRD profiles measured by Curiosity in Gale crater show a basal spacing of ∼10.0 Å, which is attributed to K/Na-rich smectites. Our results support the idea that the presence of K/Na-rich smectites from Yellowknife Bay to Glen Torridon indicates that a lake existed in the 3500 million-year-old Gale crater, confirming that the habitable state lasted longer than previously thought.