¹N. Topping et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70069]
¹School of Physics and Astronomy, University of Leicester, Leicester, UK
Published by arrangement with John Wiley & Sons

A correlative multi-technique approach, including electron microscopy and X-ray synchrotron work, has been used to obtain both structural and compositional information of a sulfur-bearing serpentine identified in several carbonaceous chondrites (Winchcombe CM2, Aguas Zarcas CM2, Ivuna CI, and Orgueil CI), and in Ryugu samples returned by the Hayabusa2 mission. S-K edge X-ray absorption spectroscopy was used to determine the oxidation state of sulfur in the serpentine in all samples except Ryugu. The abundance of this phase varies across these samples, with the largest amount in Winchcombe; ~12 vol% of phyllosilicates are identified as sulfur-bearing serpentine characterized by ~10 wt% SO3 equivalent. HRTEM studies reveal a d001-spacing range of 0.64–0.70 nm across all sulfur-bearing serpentine sites, averaging 0.68 nm, characteristic of serpentine. Sulfur-serpentine has variable S6+/ΣStotal values and different sulfur species dependent on specimen type, with CM sulfur-bearing serpentine having values of 0.1–0.2 and S2− as the dominant valency, and CIs having values of 0.9–1.0 with S6+ as the dominant valency. We suggest sulfur is structurally incorporated into serpentine as SH− partially replacing OH−, and trapped as SO42− ions, with an approximate mineral formula of (Mg Fe2+ Fe3+ Al)2-3(Si Al)2O5(OH)5-6(HS−)1-2(SO4)2−0.1-0.7. We conclude that much of the material identified in previous studies of carbonaceous chondrites as TCI-like or PCPs could be sulfur-bearing serpentine. The relatively high abundance of sulfur-bearing serpentine suggests that incorporation of sulfur into this phase was a significant part of the S-cycle in the early Solar System.

^1,2,3Hongyi Chen, ¹Jiankai Zhou, ^1,2Lanfang Xie, ^1,2Jinyu Zhang, ^1,2Zhipeng Xia
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2025.116873]
¹Institution of Meteorites and Planetary Materials Research, Key Laboratory of Planetary Geological Evolution of Guangxi Provincial Universities, Guilin University of Technology, Guilin 541006, China
²Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, Guilin University of Technology, Guilin 541006, China
³Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources in Guangxi, Guilin University of Technology, Guilin 541004, China
Copyright Elsevier

The Mg-suite lithologies, particularly pink spinel-bearing rocks, provide critical insights into the Moon’s crust-mantle interactions and impact metamorphism. However, discrepancies persist between remote sensing interpretations and laboratory analyses regarding the petrological characteristics of pink spinel anorthosite (PSA) or pink spinel troctolite (PST). The unbrecciated lunar meteorite NWA 12279, identified as a pink spinel-bearing troctolitic anorthosite (PSTA), offers a pristine record with well-preserved igneous textures, minimal shock metamorphism (S1–S2), and low terrestrial weathering (W0–1) affecting its mafic minerals and spinels. Combined petrological, mineral chemical, Visible-Near Infrared (VNIR) spectroscopy, and Raman spectroscopic analyses reveal a homogeneous composition dominated by anorthite (81.8 ± 0.1 vol%, An = ~97.2), olivine (11.7 ± 1.3 vol%, Fo = ~76.8), augite-dominated pyroxene (4.75 ± 0.45 vol%, En = ~57.4), and Mg-spinel (0.96 ± 0.48 vol%, Mg# = ~82.4). Reflectance spectra from six selected profiles across the sample section show diagnostic absorptions at 1050 nm (olivine), 1950 nm (Mg-spinel), and 2300–2350 nm (high-Ca pyroxene), with spectral contrasts that correlate directly with the spatial distribution of spinel. Regions enriched in spinel display a notably stronger absorption depth at 1950 nm. Furthermore, we establish well-defined linear correlations (R2 ≥ 0.971) under low-shock conditions (<4 GPa) that enable robust in-situ composition prediction. These quantitative models—olivine Fo from Peak A (~820 cm−1; y = 3.050× – 2430), spinel Mg# from Peak B (~670 cm−1; y = 0.0461× + 50.82), and pyroxene En from Peaks C (~661 cm−1; y = 2.635× – 1701.5) and D (~1007 cm−1; y = 2.547× – 2522.4). These quantitative models help resolve orbital detection discrepancies for Mg-spinel-rich lithologies and provide essential ground truth for lunar mineralogy. Our findings demonstrate that even modest Mg-spinel abundances of ~1.0 vol% can produce detectable spectral signatures, challenging existing genetic models for lunar crustal evolution. This study underscores the value of Raman spectroscopy for future lunar missions and indicates a need to recalibrate orbital interpretations of Mg-suite lithologies.

¹Jintuan Wang et al. (>10)
Proceedings of the National Academy of Sciences of the USA 122, e2501614122 Open Access Link to Article [https://doi.org/10.1073/pnas.2501614122]
¹State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China

The impact history of the Moon provides the opportunity to better understand mass transfer in the Solar System. While Earth’s meteorite collection serves as a key reference for material flux in the Earth–Moon system, it suffers from profound biases arising from Earth’s orbital dynamics and atmospheric filtering. Systematic identification and classification of meteorites on the airless Moon thus provide additional critical constraints for reconstructing the primordial accretion history and impactor population of the inner Solar System. However, identifying impactors on the Moon remains challenging due to their vaporization upon colliding at high velocities with the lunar surface. In situ remote sensing has previously detected chondritic impactor materials in the South-Pole-Aitken (SPA) basin of the far side of the Moon. The first opportunity to measure materials from the SPA basin has come via the Chang’e-6 (CE-6) mission, which returned samples from the Apollo basin inside the SPA basin. In this study, we screened seven olivine-porphyritic clasts as potential impactor relics in regolith returned by the CE-6 mission. These clasts were identified, via textural characterization, olivine Fe–Mn–Zn systematics, and in-situ triple oxygen isotopes, as impact relics solidified from melted chondritic parent bodies. Intriguingly, the parent body of all the identified impactor relics in this study resemble CI-like chondrites, a volatile-rich meteorite group that is relatively rare in Earth’s meteorite collection. The detection and classification of these impactor relics impose significant constraints on the proportions of meteoritic materials in the Earth–Moon system and their potential contributions to water inventories on the lunar surface.

¹R. Keerthana, ¹R. Annadurai, ²K.N. Kusuma
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2025.116871]
¹Department of Civil Engineering, Faculty of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur 603 203, Tamil Nadu, India
²Department of Earth Sciences, Pondicherry University, Puducherry 605 014, India
Copyright Elsevier

This study investigates the morphology, mineralogy, and chronology of the Briggs crater (37 km diameter), situated west of the Oceanus Procellarum, employing high-resolution data from recent lunar missions. Lunar Reconnaissance Orbiter (LRO) images, Terrain Mapping Camera (TMC) Ortho images, and Digital Elevation Models (DEMs) from both the Chandrayaan-2 and Kaguya were employed to study the morphology of the crater. The morphological investigation identified distinct features in Briggs Crater, including a well-preserved crater rim, terraced walls, a convex floor indicative of subsurface uplift, an uplifted central peak, mounds, and prominent NE-SW and N-S trending concentric and radial fractures. Additionally, a fresh impact crater and localized slumping along the crater walls suggest ongoing surface modifications. Briggs Crater exhibits characteristics of a Class-2 Floor-Fractured Crater (FFC), including an uplifted floor and prominent concentric fractures, consistent with previously established classifications. The presence of radial and concentric fractures on the Briggs Crater floor suggests a combination of brittle and ductile deformation. Variations in fracture dimensions indicate differential stress distribution during floor uplift, likely influenced by subsurface magmatic intrusion or impact-induced processes. Integrated Band Depth (IBD) and Mineral indices-based color composite images were generated using M³ datasets to better understand mineralogy. These images enable the extraction of spectral signatures for mineralogical investigation and highlight the diversity of lithological composition. Spectral absorption analysis, IBD mapping, and mineral indices collectively confirm that the central peak exposes fresh High-Calcium Pyroxene (HCP) from deeper crustal levels, while the floor, rim, wall, and ejecta show weaker, mixed, and weathered pyroxene signatures. Integrating morphology and mineralogy with Crater Size-Frequency Distributions (CSFD)-based chronology, it has been suggested that Briggs Crater formed during the late Imbrian period (3.6 Ga). The N-S trending concentric fractures on the Briggs crater floor likely represent tectonic or magmatic activity that occurred between ~310 Ma and ~ 270 Ma during the Eratosthenian period, significantly after the initial crater formation.

¹Peter Mc Ardle,¹Rhian H. Jones,²Patricia L. Clay,¹Romain Tartèse,¹Ray Burgess,²Brian O’Driscoll,³Eric W.G. Hellebrand,¹Jonathan Fellowes,⁴Arthur Goodwin,¹Lewis Hughes
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70065]
¹Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
²Department of Earth and Environmental Sciences, University of Ottawa, Ottawa, Ontario, Canada
³Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
⁴Ordnance Survey, Southampton, UK
Published by arrangement with John Wiley & Sons

Enstatite chondrites (ECs) formed on at least two parent bodies, EH and EL. After the accretion of the EC parent bodies, EC material was subjected to varying degrees of parent body thermal metamorphism (measured by petrologic types 3–6), due to heat released by radioactive isotope decay. Current schemes to determine the petrologic type of the ECs are qualitative and ambiguous, and many studies have included known or misclassified shock-melted ECs, which altogether have led to inconsistent classifications. In this study, we attempt to distinguish shock-melted ECs from other ECs so that we can assess the effects of thermal metamorphism alone. We identified a suite of geochemical parameters that allow us to classify rapidly cooled, quenched shock-melt ECs, including high-Fe (Mg,Mn,Fe)S monosulfide, high-Cr troilite, and high-Ni kamacite. We then screened out shock-melted samples. This then allowed us to establish a quantitative scheme to determine the petrologic type of an EC. This classification scheme is based on the petrography and geochemistry of glass, silicate minerals, sulfides, and metal. Specifically, for EH chondrites (which are similar but distinct from the EL group), among other parameters, the size and abundance of feldspar progressively increase from EH3 to EH6 (<13 μm, <8.5% modal% to >13 μm, 11.5 modal%), while the FeO content of enstatite changes from types 3–4 to types 5–6 (<0.45 wt% to >0.45 wt%). Additionally, we build on the work of others to propose a scheme that subdivides the EH3. Using the average Cr2O3 content of olivine, we divide the EH3 and EH4 chondrites into EH3Low (mean Cr2O3 > 0.25 wt%) and EH3High-EH4 subtypes (Cr2O3 < 0.25 wt%).

¹Béatrice Luais, ²Guillaume Florin
Earth and Planetary Science Letters 672, 119663 Link to Article [https://doi.org/10.1016/j.epsl.2025.119663]
¹Université de Lorraine, CNRS, CRPG, Nancy, F-54000, France
²Laboratoire Magmas et Volcans, Université Clermont Auvergne, CNRS, IRD, OPGC, F-63000, Clermont-Ferrand, France
Copyright Elsevier

The warm, reduced, volatile-poor inner Solar System and cold, oxidized, volatile-rich outer Solar System are characterized by neutron-poor and neutron-rich isotopic anomalies, respectively. Nucleosynthetic isotopic anomalies recorded in meteorites, asteroidal bodies, and planets are thus indicative of their regions of formation. However, whether these reservoirs evolved as closed systems or underwent some degree of intermixing remains uncertain. Here, we report new high-precision mass-dependent germanium isotopic compositions revealing that carbonaceous chondrites exhibit higher and more variable δ74/70Ge values than ordinary chondrites, defining a strong continuous trend in both Ge concentrations and isotopic compositions. We highlight that similar strong correlations with matrix mass fraction occur across all chondrite groups, but that the non-carbonaceous (NCC, inner Solar System)–carbonaceous (CC, outer Solar System) dichotomy observed in ε48Ca, ε 54Cr, ε 50Ti, and ε64Ni nucleosynthetic anomalies is maintained. In the δ74/70Ge vs. ε 48Ca, ε 54Cr, ε 50Ti, and ε 64Ni spaces, two distinct mixing lines are resolved within both the NCC and CC reservoirs, between NCC and CC-type chondrules and CI-type matrix. Extending the NCCsingle bondCI chondrite correlation to primitive achondrites, main-group pallasites, and the mantles of Mars and Earth reveals that these silicate reservoirs plot away from the OCsingle bondCI mixing lines, highlighting the possible existence of a neutron-poor matrix component in the inner Solar System. Overall, the Ge isotopic systematics of the Solar System suggest that chondrules and their matrices did not form exclusively in a single reservoir, but rather formed throughout the inner and outer Solar System.

¹Dustin Trail, ²Mélanie Barboni, ¹Miki Nakajima, ^1,3Kim A. Cone
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.10.043]
¹Department of Earth & Environmental Sciences, University of Rochester, Rochester, NY, USA
¹School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
³Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, TX, USA
Copyright Elsevier

The Moon underwent extensive internal and external modification following the crystallization of a global magma ocean. However, the isotopic record from this formative period remains poorly constrained. Here, we present the first comprehensive study of coupled δ18OVSMOW and δ30SiNBS28 compositions in 67 lunar zircons from Apollo 14 samples, spanning crystallization ages from 4.34 to 3.93 Ga, a critical 400-million-year window of early lunar history. The zircons exhibit remarkably uniform isotopic compositions throughout this interval, with δ18O = 5.66 ± 0.23 ‰ (1 s.d.) and δ30Si = –0.30 ± 0.16 ‰ (1 s.d.). These values are consistent with both bulk silicate Moon estimates and whole-rock analyses, suggesting minimal isotopic fractionation between zircon-forming melts and their source reservoirs. Importantly, we find no systematic isotopic variations with age, sample, or crystallization temperature. This isotopic uniformity persisted despite large-scale geological processes, including crustal formation, basin-forming impacts, and possible mantle overturn. This implies that neither primary differentiation processes nor later reworking produced detectable Si or O isotope heterogeneities in the zircon source regions, at least within the nearside Procellarum KREEP Terrane. Taken together, these results are consistent with lunar silicate reservoirs being well mixed and isotopically equilibrated by ∼4.3 Ga within Fra Mauro, and possibly more broadly, setting a stringent constraint for models of lunar differentiation.

¹Hairuo Fu, ¹Stein B. Jacobsen
Earth and Planetary Science Letters 672, 119697 Link to Article [https://doi.org/10.1016/j.epsl.2025.119697]
¹Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA
Copyright Elsevier

Emerging evidence of strikingly similar Earth–Moon refractory lithophile element compositions provides a key constraint on lunar origin, underscoring the need for a novel framework to test competing Moon formation models. Here, we evaluate whether the canonical giant-impact hypothesis can account for this compositional similarity. We model depth-dependent refractory element heterogeneity within the differentiated Moon-forming impactor and proto-Earth and integrate these chemical signatures with the canonical giant-impact sampling to predict the Moon’s composition. Our modeling shows that the canonical model would lead to a highly fractionated proto-lunar disk composition relative toEarth’s mantle and cannot reproduce the observed Earth–Moon similarity, when mantle compositional differentiation within the pre-impact bodies is considered. This result holds true irrespective of whether density-driven mantle overturn occurred in the pre-impact bodies. Instead, the observed similarity favors extensive post-impact homogenization of the proto-lunar disk, a process consistent with a high-energy giant-impact Moon formation scenario (e.g., Synestia).

¹Robin L. Haller, ¹Martin R. Lee
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.10.034]
¹School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK
Published by arrangement with John Wiley & Sons

The most abundant group of carbonaceous chondrites are the Mighei-like (CM) meteorites, and they span petrologic types ranging from almost unaltered (CM3) to heavily aqueously processed (CM1). The factors that controlled the extent of aqueous alteration that CM chondrites experienced on their parent body/bodies are debated and remain poorly constrained. Geochemical models, and equilibrium models in particular, are powerful tools for emulating water–rock (W/R) interactions as a function of different parameters and conditions. In order to investigate possible CM chondrite alteration conditions and evaluate controlling factor(s) on petrologic type we modelled the interaction of a CM3 proxy, the CO3.0 chondrite Dominion Range 08006, with a fluid under different temperatures (1–150 °C), W/R ratios (by mass) (0.2–5) and solute concentrations (0.2–2 mol/kg CO2, 0.02–0.2 m NH3, 0.01–0.1 m H2S and 0.001–0.01 m HCl). Five additional scenarios that use the same parameter space but with differences in properties including pressure and redox conditions were also created to further investigate the controls on petrologic type. Systems that are CM chondrite-like from their close similarity to the mineralogy of CM meteorites as determined by sample analysis can form under a wide range of temperatures (1–140 °C), W/R ratios (by mass) (0.3 – 5), solute concentrations (0.2 – 2 m CO2), pH (8.5 – 12.6) and pe (−10.8 – −6.6). Across the different scenarios CM2-like systems are most abundant followed by CM1-like, whereas CM1/2-like systems are rare. Differences in petrologic type can be mainly attributed to variations in temperature, with CM1s overall being formed by alteration at higher temperatures (80–140 °C) than CM2s (1–105 °C). CM1/2 chondrites might be produced by elevated W/R ratios (by mass) and/or solute concentrations. From a mineralogical perspective, CM chondrites of different petrologic type might have originated from contrasting regions of a singular, thermally stratified parent body. Some differences between model results and CM chondrite samples could be addressed by more sophisticated tools like kinetic modelling.

^1,2Martin Bizzarro,^1,3Anders Johansen,⁴Caroline Dorn
Nature Reviews Chemistry 9, 378–396 Link to Article [DOI https://doi.org/10.1038/s41570-025-00711-9]
¹Centre for Star and Planet Formation, Globe Institute, University of Copenhagen, Copenhagen, Denmark
²Institut de Physique du Globe de Paris, Université de Paris, Paris, France
³Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Lund, Sweden
⁴ETH Zurich, Institute for Particle Physics and Astrophysics, Zurich, Switzerland

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