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

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

^1,2Ritesh Kumar Mishra,³Kuljeet Kaur Marhas,⁴Justin Ibrahim Simon,⁵Yves Marrocchi,⁵Johan Villeneuve
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70062]
¹Independent Researcher, Dhawalpur, India
²Veer Kunwar Singh University, Ara, India
³Planetary Sciences Division, Physical Research Laboratory, Ahmedabad, India
⁴Astromaterials Research and Exploration Science Division, NASA-Johnson Space Center, Houston, Texas, USA
⁵Centre de Recherches Pétrographiques et Géochimiques, Nancy, France
Published by arrangement with John Wiley & Sons

Ordinary, enstatite, and Rumuruti type have the lowest abundance of refractory inclusions amongst chondritic meteorites. Calcium-aluminum-rich inclusions (CAIs) within these are hallmarked by a relatively small average diameter of ~45 μm (size range 4–382 μm). One CAI, one amoeboid olivine aggregate (AOA), one spinel-bearing chondrule, and two aluminum-rich chondrules from Semarkona (LL3.00) along with one CAI each from Allan Hills (ALHA) 81251 (LL3.2) and Chainpur (LL3.4) were identified following an extensive search. These objects were studied for their petrography, mineral chemistry, relative (26Al) chronology, and three oxygen isotopic compositions. The initial 26Al/27Al ratio of (4.96 ± 0.14) × 10−5 (2σ) in a type A CAI in Chainpur, the largest size (1500 × 1200 μm) found so far in the noncarbonaceous (ordinary) chondrites, forming in an 16O-rich early solar system reservoir (Δ17O = −24‰) is consistent with previous studies. The Chainpur CAI 1 has a Wark–Lovering rim, the first reported case within the noncarbonaceous chondrites. The hibonite–pyroxene spherule in ALHA81251 (CAI 1) is the first reported case of a hibonite–pyroxene spherule in the ordinary chondrites of these rare objects (~12 known so far) within meteorites. The hibonite–pyroxene spherule in ALHA81251 has a low abundance of 26Al/27Al ratio of (1.2 ± 0.6) × 10−5 with Δ17O of ~ −14.5‰ ± 2.0‰. An olivine-phyric Al-rich chondrule in Semarkona (Ch 54) formed at ~0.9 Ma with Δ17O of ~0‰, while Semarkona (Ch 44) formed in a relatively 16O-rich reservoir with Δ17O of ~ −2.0‰. The spinel-bearing chondrule in Semarkona (Ch 205) shows no resolved excess in Δ26Mg and has a planetary-like oxygen isotopic composition. Oxygen isotope composition and 26Al-26Mg relative chronology of these objects confirm their origin and evolution under cosmochemical conditions similar to their “typical” carbonaceous kindred and extend the knowledge of the cosmochemical environment in the early solar system.

¹Takumi Miura,²Hidenori Terasaki,^2,3Hyu Takaki,²Kotaro Kobayashi,⁴Geoffrey David Bromiley,²Takashi Yoshino
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70068]
¹Department of Earth and Space Science, Osaka University, Osaka, Japan
²Department of Earth Sciences, Okayama University, Okayama, Japan
³Institute for Planetary Materials, Okayama University, Tottori, Japan
⁴School of Geosciences, The University of Edinburgh, Edinburgh, UK
Published by Arrangement with John Wiley & Sons

During precursor stages of planet formation, many planetesimals and planetary embryos are considered to have differentiated, forming an iron-alloy core and silicate mantle. Percolation of liquid iron-alloy in solid silicates is one of the major possible differentiation processes in these small bodies. Based on the dihedral angles between Fe-S melts and olivine, a criterion for determining whether melt can percolate through a solid, it has been reported that Fe-S melt can percolate through olivine matrices below 3 GPa in an oxidized environment. However, the dihedral angle between Fe-S melts and orthopyroxene (opx), the second most abundant mineral in the mantles of small bodies, has not yet been determined. In this study, high-pressure and high-temperature experiments were conducted under the conditions of planetesimal and planetary embryo interiors, 0.5–5.0 GPa, to determine the effect of pressure on the dihedral angle between Fe-S melts and opx. Dihedral angles tend to increase with pressure, although the pressure dependence is markedly reduced above 4 GPa. The dihedral angle is below the percolation threshold of 60° at pressures below 1.0–1.5 GPa, indicating that percolative core formation is possible in opx-rich interiors of bodies where internal pressures are lower than 1.0–1.5 GPa. The oxygen content of Fe-S melt decreases with increasing pressure. High oxygen contents in Fe-S melt reduce interfacial tension between Fe-S melt and opx, resulting in reduced dihedral angles at low pressure. Combined with previous results for dihedral angle variation of the olivine/Fe-S system, percolative core formation possibly occurs throughout bodies up to a radius of 1340 km for an olivine-dominated mantle, and up to 770 km for an opx-dominated mantle, in the case of S-rich cores segregating under relatively oxidizing conditions. For mantles of small bodies in which abundant olivine and opx coexist, the mineral with the largest volume fraction and/or smallest grain size will allow formation of interconnected mineral channels, and, therefore, the wetting property of this mineral determines the wettability of the melt, that is, controls core formation.

¹A.R.Russell et al. (>10)
Journal of Geophysical Reserac (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009244]
¹Arizona State University, Tempe, AZ, USA
Published by arrangement with John Wiley & Sons

The Martian surface preserves evidence of a global climate transition from wetter to drier conditions, but the nature of the fluids involved in this evolution remains poorly constrained. In Gale crater, the clay-sulfate transition and presence of evaporite mineral assemblages can provide insights into the properties of these fluids and the timing of environmental change. While traversing through the Chenapau member of the sulfate-bearing unit in Gale crater, the Curiosity rover encountered a set of dark-toned veins enriched in Na and Cl, suggestive of halite. However, previous halite detections in Gale crater have been limited to occurrences along the edges of Ca-sulfate veins or nodules, suggesting a unique origin for this set of veins. Here, we hypothesize that these veins formed through the infiltration of saline fluids along pre-existing hydraulically induced fractures. These fluids permeated into the host rock beyond the primary fractures, precipitating halite and cementing the fractures. Using Mastcam and ChemCam spectra, we found that the veins displayed a downturn in the near-infrared wavelengths, consistent with the presence of ferrous iron. Furthermore, textural analysis of the veins reveals host rock material preserved within the veins. ChemCam laser-induced breakdown spectroscopy observations also support the presence of a minor Fe component in the veins and halite concentrated along the center of the fractures. Our results demonstrate that these veins represent a distinct class of diagenetic features in Curiosity’s mission that record an important transition in near-surface fluid chemistry consistent with a transition to a drier environment.