¹Addi Bischoff et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70060]
¹Institut für Planetologie, University of Münster, Münster, Germany
Published by arrangement with John Wiley & Sons

On October 24, 2024, an impressive fireball was visible over Austria. After the possible strewn field was calculated, the first sample of the Haag meteorite, with a mass of 8.76 g, was discovered on November 2, 2024, 8 days after the fireball event. Four more samples were found afterward putting the total sample mass at about 151 g. Short-lived radionuclides were measured shortly after recovery on a small sample, which was also used for almost all analyses presented here. Results confirm that the Haag meteorite derived from the bolide fireball event. Haag is a severely fragmented ordinary chondrite breccia and consists of typical equilibrated and recrystallized lithologies (LL4-6) as well as impact-related lithic clasts, such as dark, fine-grained impact breccias. Most fragments are highly recrystallized (type 6), but some show a well-preserved chondritic texture, which is of petrologic type 4 since the olivines are equilibrated. The olivines in the bulk rock have Fa contents of 29.5 ± 0.5 mol%, whereas the low-Ca pyroxenes have compositions of Fs23.9±1.4Wo1.6±0.7 with slightly variable Fs contents up to 28 mol%. However, the occurrence of type 3 fragments in other parts of the rock cannot completely be ruled out. Many clasts are moderately shocked (S4; C-S4). Using the fragment with the lowest degree of shock to determine the bulk rock’s shock degree, Haag has an overall shock degree of S2 (C-S2). The LL chondrite classification is also supported by O isotope data, the results of bulk chemical analysis, and the physical properties of density and magnetic susceptibility. The nucleosynthetic Ti and Cr isotope data confirm that Haag is an ordinary chondrite, related to the noncarbonaceous (NC) meteorites. Haag does not contain detectable amounts of solar wind-implanted noble gases, and we rule out any substantial exposure at the direct surface of the parent body. Based on noble gases, Haag has an exposure age of 21–24 Ma and a pre-atmospheric meteoroid radius of 20–85 cm with a sample depth between 4 and 5 cm below the meteoroid surface, consistent with constraints from cosmogenic radionuclides. The soluble organic compositions of Haag are consistent with the profiles of the Stubenberg (LL6) breccia and show characteristics consistent with the complex shock, brecciation, and lithification history of the breccia. Haag and Stubenberg fell near each other (110 km away) within just 8 years. Since only 8.5% (about 110) of meteorite falls worldwide are LL chondrites, it is remarkable that two LL chondrites fell near each other in such a short time.

¹I. Baziotis,^2,3L. Ferrière,⁴C. Ma,⁴J. Hu,⁵D. Palles,⁴P. D. Asimow
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70054]
¹Department of Natural Resources Management and Agricultural Engineering, Agricultural University of Athens, Athens, Greece
²Natural History Museum Vienna, Vienna, Austria
³Natural History Museum Abu Dhabi, Abu Dhabi, United Arab Emirates
⁴Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
⁵Theoretical & Physical Chemistry Institute, National Hellenic Research Foundation, Athens, Greece
Published by arrangement with John Wiley & Sons

We report new results from a study of shock-related features in the L6 ordinary chondrites Northwest Africa (NWA) 4672 and NWA 12841. Our observations confirm the occurrence of eight high-pressure (HP) minerals in each meteorite, namely, ringwoodite, majorite, akimotoite, wadsleyite, albitic jadeite, lingunite, tuite, and xieite. Based on the calibration of phase stability fields and majorite chemical variations from static experiments, we estimate peak shock conditions of 18–23 GPa and 1800–2100°C. However, both meteorites also contain minerals thought to record lower pressures, 14–18 GPa for wadsleyite, and possibly ~11.5 GPa for albitic jadeite. These are interpreted to have formed by cooling during partial release from the peak shock state. Although the presence of discrete shock melt veins demands spatial heterogeneity in the temperature field, we interpret the record of HP mineralogy in terms of temporal rather than spatial variation in pressure–temperature conditions during the shock and release event. Specifically, we infer that the cooling of shock melt veins to their liquidus occurred near peak pressure, whereas decompression began before the melt veins reached their solidus. NWA 4672 and NWA 12841 also display dense networks of shock melt veins, metal–sulfide segregations, and dark shock zones, implying a high density of pre-existing weak zones and, thus, a high likelihood of fragmentation during atmospheric entry. A comparison with the Suizhou L6 chondrite, in which a total of 26 HP phases have been identified, suggests that differences in the identification and number of observed HP polymorphs mostly reflect differences in the completeness and spatial scale of analytical studies rather than a true difference in the intensity of shock processing. It remains quite likely that many shocked L chondrites host more HP phases than have been recognized so far. These new results indicate a need for further high-resolution studies of L chondrites to distinguish between observational bias and true variations in the range of shock states they experienced.

¹Léna Jossé,¹Zélia Dionnet,¹Alice Aléon-Toppani,¹Rosario Brunetto,²Andrew King,³Emmanuel Gardés,⁴Eva Heripré,^1,5Damien Loizeau,¹Sasha Cryan,⁶Kentaro Hatakeda
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70056]
¹Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale (IAS), Orsay, France
²SOLEIL Synchrotron, Gif-sur-Yvette, France
³Laboratoire Magmas et Volcans (LMV), Université Clermont Auvergne, CNRS, IRD, Clermont-Ferrand, France
⁴Procédés et Ingénierie en Mécanique et Matériaux (PIMM), Arts et Métiers Sciences et Technologies, CNRS, CNAM, Paris, France
⁵Qualisat, Bièvres, France
⁶Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Japan
Published by arrangement with John Wiley & Sons

Extraterrestrial breccia samples are formed through impact-related processes that combine the fragments of distinct lithologies. As such, they are valuable indicators of the complex formation and evolution history of planetesimals in our solar system. Samples from asteroid (162173) Ryugu, returned to the Earth by the Hayabusa2 mission in December 2020, were characterized as breccias. The boundaries of mineralogical assemblages are typically drawn manually based on interpreted results from specific techniques, mostly performed on artificially produced 2D surfaces. This process inherently introduces subjectivity. Here, we present a semi-automated analytical method using synchrotron radiation micro X-ray computed tomography (SR-μXCT) data, called the Local Histogram method. It enables an unsupervised detection and 3D visualization of a few tens to hundreds of micrometer-sized lithologies showing sub-micrometer heterogeneities. We developed the method on a millimeter-sized Ryugu sample (A0159) in combination with a more traditional global grayscale threshold segmentation. In A0159, we report five distinct lithologies. They were confirmed and further characterized by an additional scanning electron microscopy (SEM) analysis on Xenon plasma-focused ion beam (Xe-pFIB) produced sections. Some lithologies show specific relationships with large fractures, while one is particularly enriched in sub-micrometer sulfides. A0159 is rich in carbonates and hosts the largest millimeter-scale dolomite vein seen on Ryugu.

¹B. Marty,¹L. Zimmermann,¹E. Füri,¹D. V. Bekaert,²J. J. Barnes,³A. N. Nguyen,^3,4,5H. C. Connolly,²D. S. Lauretta

Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70058]
¹CNRS, CRPG, UMR 7358, Université de Lorraine, Nancy, France
²Lunar and Planetary Laboratory, The University of Arizona, Tucson, Arizona, USA
³ARES (Astromaterials Research and Exploration Science), NASA Johnson Space Center, Houston, Texas, USA
⁴Department of Geology, Rowan University, Glassboro, New Jersey, USA
⁵Department of Earth and Planetary Science, American Museum of Natural History, New York, New York, USA
Published by arrangement with John Wiley & Sons

We report the elemental and isotopic abundances of all stable noble gases (helium, neon, argon, krypton, and xenon) in eight particles from asteroid Bennu returned by NASA’s OSIRIS-REx mission. We also report nitrogen abundances and isotopic ratios that were analyzed alongside neon and argon in four additional Bennu particles. These analyses confirm the similarities of Bennu material with Ivuna-type carbonaceous (CI) chondrites. The nitrogen isotopic compositions show intra- and inter-particle variations, pointing to the heterogeneous distribution of various N-bearing phases, while the abundances of nitrogen are within the range of those measured in CIs. Noble gas data indicate mixing between Q-like noble gases (a ubiquitous noble gas component found in most classes of primitive meteorites, presumably formed by noble gas incorporation into organic materials within the ionized regions of the parent cloud or in the protoplanetary disk) and various presolar components originally hosted by refractory grains that survived the high enthalpy birth of the solar system. The noble gases also include secondary contributions of three types: (i) noble gas isotopes produced by radioactivity, (ii) solar wind implantation, mostly identified in the light noble gas (He and Ne) isotopic compositions, and (iii) cosmogenic noble gases produced by interaction with high-energy cosmic rays, permitting us to estimate how long fresh surfaces were irradiated. We find that cosmic ray exposure (CRE) durations of Bennu material vary mostly between 1 and 3 Ma. These CRE ages are consistent with (i) radionuclide studies suggesting surface exposure for 2–7 Ma, (ii) small crater retention ages of 1.6–2.2 Ma, and (iii) the 1.75 ± 0.75 million years that Bennu is estimated to have been dynamically decoupled from the asteroid belt. In contrast to CRE ages, we find a maximum duration of solar wind irradiation of ≤100,000 a, in agreement with exposure duration of <85,000 a from solar energetic particle tracks and microcrater densities. The noble gas abundances in Bennu and Ryugu samples are higher by a factor ≥2 compared to CI meteorites, whereas their isotopic compositions are similar. This difference between material sampled directly from asteroids and their meteoritic equivalent suggests degradation of the latter through contact with the terrestrial environment. Neon–argon variations point to a potential genetic relationship between Bennu, Ryugu, CI materials on the one hand, and the terrestrial atmosphere on the other.

¹S. A. Singerling,²A. J. Brearley
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70061]
¹Schwiete Cosmochemistry Laboratory, Goethe University, Frankfurt, Germany
²Department of Earth and Planetary Sciences, MSC-03 2040, 1 University of New Mexico, Albuquerque, New Mexico, USA
Published by arrangement with John Wiley & Sons

We conducted a scanning electron microscopy (SEM) and transmission electron microscopy (TEM) study of sulfide–metal assemblages (SMAs) in minimally to moderately altered CR2 chondrites. The assemblages occur on chondrule rims and consist of kamacite cores rimmed by pyrrhotite. The kamacite and pyrrhotite share orientation relationships, arguing for a genetic link. The SMAs contain secondary alteration products, including nanoscale magnetite at the sulfide–metal interface (minimally altered SMAs) and magnetite, serpentine, nanoscale Ni-rich metal at metal–magnetite interfaces, and Ni,S-bearing reaction fronts within magnetite (moderately altered SMAs). We argue the SMAs initially formed in the solar nebula from the separation of immiscible metal and silicate melts followed by sulfidization of the metal. Aqueous alteration on the asteroidal parent body caused the kamacite to transform into magnetite and the magnetite to transform into serpentine. Alteration of kamacite to magnetite occurred under oxidizing and alkaline conditions, whereas alteration of magnetite to serpentine occurred under reducing, alkaline, and higher aSiO2 conditions. Serpentinization of magnetite appears to be a relatively common process in some carbonaceous chondrites. Additionally, theoretical and experimental studies are needed that simulate the oxidation of metal by H2O gas and water and also serpentinization of magnetite to form serpentine with variable Mg-Fe contents.

¹Gabriel Zachén,¹Carl Alwmark,¹Sanna Alwmark,^2,3Ludovic Ferrière,^4,5Roger H. Hewins
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70051]
¹Department of Geology, Lund University, Lund, Sweden
²Natural History Museum Vienna, Vienna, Austria
³Natural History Museum Abu Dhabi, Abu Dhabi, United Arab Emirates
⁴IMPMC, MNHN, UMR CNRS 7590, Sorbonne Université, Paris, France
⁵Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey, USA
Published by arrangement with John Wiley & Sons

Mesosiderites are rare, differentiated meteorites, so-called stony-iron meteorites—they are impact breccias composed of an unusual mix of crustal basalt and pyroxenite, core-derived metal, but no mantle materials. This odd mixture makes their origin enigmatic and has inspired many different formation theories over the last several decades. Some of the outstanding questions have regarded the origin of the metal, whether it came from another celestial body or from within the main parent body, and the puzzlingly low abundance, or absence, of mantle material in mesosiderites. The role of impacts has been central to most of the suggested theories, but mesosiderites show little to no evidence of shock metamorphism. The mystery of the origin of mesosiderites is further compounded by the relatively limited amount of published data, as well as the restricted number of samples available for research. With the detailed investigation and reclassification of the mesosiderites Lamont, Acfer 265, Queen Alexandra Range 86900 (QUE 86900), and MacAlpine Hills 88102 (MAC 88102) presented herein, our new observations shine some much-needed light on this meteorite group. Based on their petrologic and metamorphic characteristics, Lamont is classified as a B3/4, Acfer 265 and QUE 86900 as A1, and MAC 88102 as an A4 mesosiderite. The observation of multiple sets of parallel thin lamellae in high-Ca plagioclase and cristobalite in Lamont, and a silicate emulsion in QUE 86900 is proposed to be shock-related features. In both Lamont and QUE 86900, these features are interpreted to be subsequent to the initial impact, which mixed crustal and core material, and prior to deep burial. No shock-related features were noted in Acfer 265 and MAC 88102.

^1,2C. S. Harrison,¹A. J. King,²R. H. Jones,³L. Piani
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70052]
¹Planetary Materials Group, Natural History Museum, London, UK
²Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
³Centre de Recherches Pétrographiques et Géochemiques CNRS, Université de Lorraine, Metz, France
Published by arrangement with John Wiley & Sons

Phosphate minerals are significant carriers of volatiles (e.g., OH) and halogens in chondritic material; however, their origin in most groups of carbonaceous chondrites remains poorly characterized. We have determined the abundance, morphology, texture, and composition of phosphate grains in aqueously altered CI chondrites and in hydrated and thermally metamorphosed Antarctic CY chondrites using scanning electron microscopy and electron probe microanalysis. Phosphates include apatite (formula Ca5(PO4)3X, where X = F-, Cl-, OH- or other anions) and sodium-bearing magnesium phosphate, both of which formed during episodes of aqueous alteration on the CI and CY parent bodies. Apatite grains in the CI chondrites range up to 40 μm in size with a modal abundance of ~0.10 area%, while in the CYs, the largest grains are ~50 μm in size and the modal abundance is ≤0.70 area%. Analysis by secondary ion mass spectrometry (SIMS) indicates that apatite in the CYs contains ~1.0–1.8 wt% H2O, with δD values of −84‰ to 393‰ likely reflecting aqueous and thermal processing. Apatite in both the CI and CY chondrites is rich in fluorine, with fluorine abundances that range from 20 to 80 mole% of the X (anion) site. This contrasts with apatite in other chondrite groups, which is predominantly Cl-rich. Estimated bulk chondrite F abundances based on F abundance in apatite are 12–21 ppm F for the CI chondrites and 61 ppm F for the CY chondrites. This is comparable to bulk CI chondrite F abundances in the literature, suggesting that most fluorine is hosted in apatite. However, the chlorine content of CI chondrite apatite (<0.05 wt%) is too low to account for the bulk chondrite Cl abundance, indicating that Cl is hosted in other phases. Mg,Na-phosphate, a rare extraterrestrial mineral, has a modal abundance of ~0.02 area% in both the CI and CY chondrites. Mg,Na-phosphates in the CI and CY chondrites are halogen-poor (<0.15 wt%) and are typically hydrated in the CIs (analytical totals as low as 67 wt%) and dehydrated in the CYs (analytical totals >96.0 wt%). The occurrence of Mg,Na-phosphates in the CI and Antarctic CY chondrites is indicative of brines on their respective parent bodies. Similarities between the two groups, as well as with the phosphate mineral assemblage in asteroids Ryugu and Bennu, indicate that comparable fluid compositions and environmental conditions were prevalent on numerous parent bodies in the early Solar System.

¹Christopher D.K. Herd, ¹Sophie Benaroya
Geochimica et Cosmochimica Acta (in Press) (Open Access) Link to Article [https://doi.org/10.1016/j.gca.2025.10.001]
¹Department of Earth and Atmospheric Sciences, 1-26 Earth Sciences Building, University of Alberta, Edmonton, AB T6G 2E3, Canada
Copyright Elsevier

We provide an updated compilation of oxygen fugacity (fO₂) estimates for martian meteorites, with a specific focus on the shergottites. The compilation includes estimates from over 70 distinct lithologies from the martian meteorite suite, calculated from olivine-pyroxene-spinel and Fe-Ti oxide oxybarometers. Olivine-pyroxene-spinel oxybarometry was recalculated from original data sources using an updated model. Results from V- in-olivine and Eu/Gd oxybarometry from the literature are provided for comparison. Oxygen fugacity data are plotted against chondrite-normalized La/Yb ratio to critically examine the correlation between fO₂ and incompatible trace element (ITE) enrichment previously postulated. We find that the correlation holds, when factors including differences in petrogenetic histories, distinctions between shergottite petrologic types, and early vs. late crystallizing assemblages, are taken into consideration. We model the degassing of H, C and S species from primitive martian magmas using the MAGEC model (Sun and Lee, 2022) and successfully reproduce the 2–3 log unit increase recorded within olivine-phyric shergottites between early and late crystallizing assemblages. We find that volatile degassing can account for most of the fO₂ increase in the olivine-phyric shergottites, without requiring extensive auto-oxidation, as long as their fO₂ remains at or below a value equivalent to the fayalite-magnetite-quartz (FMQ) equilibrium throughout their crystallization. With these considerations in mind, we propose a martian mantle redox-ITE trend defined by shergottite sources: a depleted source (La/Yb ∼ 0.1) with fO₂ = FMQ-4 ± 0.7, an intermediate source (La/Yb ∼ 0.5) at fO₂ = FMQ-3 ± 0.75 and an enriched source (Lab/Yb ∼ 1) at fO₂ = FMQ-2 ± 0.75. The depleted/reduced source is likely graphite saturated.

Comparisons with compilations of fO₂ from basaltic eruptives on Earth highlight fundamental differences between the two planets ultimately attributable to differences in degree of mantle convective mixing throughout their histories: terrestrial mantle sources produce basaltic eruptives with a relatively limited range of fO₂, within ±1 log unit of FMQ; any degassing from these magmas results in reduction, not oxidation. The mantle sources of the shergottites – while represented by a similarly limited range of fO₂, ∼FMQ-4 to FMQ-2 – produce basaltic eruptives with a range of low initial (magmatic) fO₂; the more reduced nature of these magmas make them more susceptible to overprinting by degassing of H-C-S species during eruption and emplacement. Whether the mantle sources inferred from the shergottites apply to other martian meteorites (or other martian igneous rocks) remains to be tested; however, post-magma ocean crystallization processes would have acted to oxidize and overprint initial mantle sources defined by the shergottite fO₂-ITE trend.

^1,2Zhiming Chen et al. (>10)
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2025JE008976]
¹State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
²College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
Published by arrangement with John Wiley & Sons

Lunar regolith contains not only materials derived from the local rock unit, but also materials transferred from remote craters, which are crucial for investigating the lithological diversity of the lunar surface. In this study, we conducted detailed petrography and geochemical analyses and measured the cross-sectional area of plagioclase fragments and impact glass particles selected from the Chang’e 6 (CE-6) regolith, the first lunar far-side returned sample. Statistics of plagioclase fragments and impact glass are used to estimate the proportion of the diverse components in the CE-6 regolith. The results reveal 35.7 vol% and 28.2 vol% exotic components in CE-6 plagioclase and impact glass fractions, respectively. As plagioclase, pyroxene and glass particles are the three dominant phases (>95 vol%) in the CE-6 regolith, together with previously reported pyroxene compositions, we estimate that the abundance of the exotic materials is 23.5–33.5 vol%. These exogeneous components include very-low-Ti (VLT) basalt (2%–3%), ferroan anorthosite (5%–9%), Mg-suite (15%–20%), KREEP-related (∼0.1%), and highlands-mare-mixed materials (∼1%). The VLT-basalt component is most likely from the mare basalt unit to the east of the landing site or beneath the local mare layer. Based on the ejecta orientations and model age of impact craters, ferroan anorthite, Mg-suite and KREEP-related materials are likely transferred from Vavilov/Pythagoras (highland anorthosite), Chaffee S/White’ (rich in mafic minerals), and Birkeland (high Th contents) craters, respectively. The abundant non-mare components in the CE-6 regolith contrast to the very scarce exotic materials in the CE-5 lunar regolith, potentially providing valuable insights into the composition of the lunar far-side.

¹Garima Sodha,¹Deepak Dhingra
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2024JE008809]
¹Department of Earth Sciences, Indian Institute of Technology Kanpur (IITK), Kanpur, Uttar Pradesh, India
Published by arrangement with John Wiley & Sons

The spatial distribution of Mg-spinel lithology at South Pole-Aitken (SPA) basin is revealed by systematic mineralogical survey along the basin rings. We report Ingenii-Thomson region as a Mg-spinel anomaly, having the largest number of exposures based on newly identified and previously reported occurrences on the Moon. The timing of Mg-spinel formation is constrained by using SPA impact as a key geological time marker. Post-SPA origin of this lithology is favored in this region due to the general lack of pervasive Mg-spinel occurrences along basin rings, being the deepest exposures of the pre-SPA crust. Our detailed mineralogical analyses also highlight several detections of Mg-spinel lithology exhibiting weak 1,000 nm absorption band, emphasizing the need for a detailed analysis of such locations. Collectively, these salient findings have important implications for understanding the compositional diversity of Mg-spinel lithology, refinement of the formation models and determining the role of Mg-spinel lithology in the lunar crustal evolution.