^1,2Laura Noel García,³Frederic Danoix,⁴Martina Ávalos,⁵Pouyan Shen,¹María Eugenia Varela
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14352]
¹Instituto de Ciencias Astronómicas, de la Tierra y del Espacio, Universidad Nacional de San Juan, CONICET, San Juan, Argentina
²Instituto de Mecánica Aplicada, Universidad Nacional de San Juan, San Juan, Argentina
³Groupe de Physique des Matériaux, UMR CNRS 6634, Saint Etienne du Rouvray, France
⁴Instituto de Física Rosario, Universidad Nacional de Rosario, CONICET, Rosario, Argentina
⁵Department of Materials and Optoelectronic Science, National Sun Yat-sen University, Kaohsiung, Taiwan, ROC
Published by arrangement with John Wiley & Sons

The presence of spheroidized plessite (SP) in mesosiderites was recently reported in the literature. This finding coupled with the poor understanding of this plessite variant, motivated us to investigate its formation process and evaluate its implications in assessing the previous proposals concerning mesosiderites’ genesis and cooling history. SP consists of spherulitic taenite particles irregularly distributed, usually surrounded by carbides, and embedded in a kamacite matrix. It has been reported in iron meteorites containing graphite, carbides, and pearlitic plessite (PP), especially in the IAB main group and the sLL and sLH subgroups. From the combination of X-ray tomography, electron backscatter diffraction, energy-dispersive spectrometry, and atom probe tomography in three samples of Vaca Muerta mesosiderite (A1, low to moderate metamorphism) from the ICATE (Argentina) collection of meteorites, we were able to identify a common crystallographic orientation between spheroids and retained taenite, the absence of PP and the carbon depletion in the metallic portion contiguous to the spheroids, and the high volumetric connectivity of the metallic portion. Based on these findings: (i) SP likely grew at the expense of pearlite lamellae, with their absence resulting from complete consumption after an extraordinarily slow cooling rate, probably succeeding a deep burial in a breccia of rock fragments. (ii) Carbon introduction would have followed plessite formation in mesosiderites at a temperature low enough to prevent carbon solid-state diffusion. (iii) Metal would have been poured in silicates, which favors the collision model between a differentiated asteroid and a molten core for mesosiderite genesis.

¹Thomas J. Barrett, ¹James F.J. Bryson, ²Kalotina Geraki
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2025.116588]
¹Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK
²Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
Copyright Elsevier

Despite being pivotal to the habitability of our planet, the process by which Earth gained its present-day hydrogen budget is unclear. Due to their isotopic similarity to terrestrial rocks across a range of elements, the meteorite group that is thought to best represent Earth’s building blocks is the enstatite chondrites (ECs). Because of ECs’ nominally anhydrous mineralogy, these building blocks have long been presumed to have supplied negligible hydrogen to the proto-Earth. However, recent bulk compositional measurements suggest that ECs may unexpectedly contain enough hydrogen to readily explain Earth’s present-day water abundance. Together, these contradictory findings mean the contribution of ECs to Earth’s hydrogen budget is currently unclear. As such, it is uncertain whether appreciable hydrogen is a systematic outcome of Earth’s formation. Here, we explore the amount of hydrogen in ECs as well as the phase that may carry this element using sulfur X-ray absorption near edge structure (S-XANES) spectroscopy. We find that hydrogen bonded to sulfur is prevalent throughout the meteorite, with fine matrix containing on average almost 10 times more Hsingle bondS than chondrule mesostasis. Moreover, the concentration of the Hsingle bondS bond is linked to the abundance of micrometre-scale pyrrhotite (Fe1-xS, 0 < x < 0.125). This sulfide can sacrificially catalyse a reaction with H2 from the disk at high temperatures to create H2S, which could be dissolved in adjoining molten silicate-rich material. Upon rapid cooling, this assemblage would form pyrrhotite encased in submicron silicate-rich glass that carries trapped H2S. These findings indicate that hydrogen is present in ECs in higher concentrations than previously considered and could suggest that this element may have a systematic, rather than stochastic, origin on our planet.

^1,2Y. Zheng,^1,2X. Yang,¹M. Valdes,^1,2,3A. M. Davis,^1,2P. R. Heck
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14351]
¹Robert A. Pritzker Center of Meteoritics and Polar Studies, Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, Illinois, USA
²Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
³Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
Published by arrangement with John Wiley & Sons

In this paper, we introduce a method for volume measurement of microparticles that includes scanning electron microscope photogrammetry with 3-D model construction. Our results show that our method limits the volume uncertainty to ±10%, which is a significant improvement compared to previous methods (which likely overestimated volume by 100%–200%). We also discuss how the size, morphology, and porosity of the sample can affect the uncertainty of volume measurement. We find that our method can have a significant impact on cosmic ray exposure age determinations based on noble gas concentration, with implications for our understanding of cosmic ray irradiation of refractory minerals in the early solar system and presolar grains in the interstellar medium.

¹Axel Wittmann,²Marc Biren
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14350]
¹Eyring Materials Center, Arizona State University, Tempe, Arizona, USA
²School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
Published by arrangement with John Wiley & Sons

Circa 300 years ago, a ~15-m iron asteroid impacted sand dunes in the Empty Quarter of Saudi Arabia, creating the Wabar craters and fragments of the IIIAB Wabar iron meteorite. A significant portion of the asteroid dissolved into the sand, forming a wide range of impactites including glassy Wabar pearls, dumbbells, and dark scoria-like material. In this study, we report the discovery of ~60–1400 nm nuggets of refractory highly siderophile elements (HSEs) dominated by Pt, Os, Ru, Ir, Re, and Rh in Wabar impact glass. These HSEs were distributed in the IIIAB iron at low parts per million and became concentrated up to ×44,000 in the nano-nuggets. The petrologic context of the nano-nuggets is consistent with the rapid dissolution of the iron meteorite into the dune sand target triggered by the impact shockwave, followed by the separation of immiscible HSEs from the silicate impact melt at 1900°C to over 2700°C. This research provides new insights into the formation processes of HSE nano-nuggets in impact glass and predicts the potential for similar findings at other impact sites.

²Larbi Zennouri,^1,2Hasnaa Chennaoui Aoudjehane,^3,4Luigi Folco,¹Taha Shisseh,⁵Abderrazak El Albani,⁵Arnaud Mazurier,¹Mohamed Hassan Leili
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14349]
¹GAIA Laboratory, Faculty of Sciences Ain Chock, Hassan II University of Casablanca, Casablanca, Morocco
²ATTARIK Foundation for Meteoritics and Planetary Science, Faculty of Sciences Ain Chock, Hassan II University of Casablanca, Casablanca, Morocco
³Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
⁴Centro per la Integrazione della Strumentazione della Università di Pisa, CISUP, Pisa, Italy
⁵Université de Poitiers, CNRS, IC2MP, Poitiers, France
Published by arrangement with John Wiley & Sons

Tamdakht meteorite is the most massive observed fall in Morocco with a total recovered mass of ~500 kg. Most of the specimens investigated in this study are covered by a well-developed primary fusion crust with thickness that reaches up to 12 mm. Macroscopic investigations reveal the development of complex fusion crust features indicative of unusual entry conditions. In some specimens, pieces of the primary fusion crust are missing, and the newly exposed areas developed a thinner fusion crust, which suggests that the former were removed during the late stages of the meteoroid’s flight. Meteorite fragments are enclosed in the primary fusion crust, implying a potential intershower debris transfer prior to the dark flight and that the broken pieces were retained by the viscous fusion crust. X-ray tomographic and backscattered electron imaging shows that the primary fusion is irregular in thickness and consists of three layers. The outer layer is mainly composed of magnetite that formed as a result of the reaction of atmospheric oxygen with Fe in the melt produced by heating. The middle layer consists of zoned olivine phenocrysts, large vesicles, and metal and sulfide grains. The innermost layer displays a lower degree of melting and contains tiny vesicles, as well as metal and iron sulfides in the form of blebs and veins invading the substrate. The textural, mineralogy, and the compositional variation of Tamdakht’s fusion crust imply a change in the degassing degree, temperature, and reaction with atmospheric oxygen from the surface inward.

¹Alexandre V. Andronikov,¹Irina E. Andronikova,¹Ondrej Pour,¹Petr Bohdalek
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14347]
¹Division of Geochemistry and Laboratories, Czech Geological Survey, Prague, Czech Republic
Published by arrangement with John Wiley & Sons

We have analyzed in situ mineral phases in a Potůčky fragment of the stony-iron IVA-an meteorite Steinbach for trace-element compositions. The studied fragment contains silicate grains (pyroxene and tridymite) interspersed with grains of metal (kamacite, plessite, and taenite) displaying Widmanstätten pattern and troilite. Multiple inclusions of chromite, troilite, and bi-mineral troilite + taenite assemblages were observed within some pyroxene grains. The data on variations in trace-element compositions in different meteorite phases are consistent with a number of models, suggesting the involvement of several processes in the generation of the lithologies presently observed in the Potůčky meteorite. These processes might have involved fractional crystallization of silicate liquid, collision, impact, shock melting, and cooling. As a result of such processes, specific trace-element composition of different mineral phases was formed. Trace-element compositions of metals and sulfides from the Potůčky meteorite are very similar to those for minerals from the LL ordinary chondrite, suggesting LL-like asteroid as a parent body for the Potůčky (IVA-an) precursor material.

¹Carole Freissinet et al. (>10)
Proceedings of the National Academy of Science of the USA (PNAS) 122, e2420580122 Open Access Link to Article [https://doi.org/10.1073/pnas.2420580122]

¹Laboratoire Atmosphères et Observations Spatiales, Université Versailles St Quentin Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt 78280, France

Organic molecules preserved in ancient Martian rocks provide a critical record of the past habitability of Mars and could be chemical biosignatures. Experiments conducted by the Sample Analysis at Mars instrument onboard the Curiosity rover have previously reported several classes of indigenous chlorinated and sulfur-containing organic compounds in Gale crater sedimentary rocks, with chemical structures of up to six carbons. Here, we report the detection of decane (C10H22), undecane (C11H24), and dodecane (C12H26) at the tens of pmol level, released from the Cumberland drilled mudstone sample, using a modified SAM analytical procedure optimized for the detection of larger organic molecules. Laboratory experiments support the hypothesis that the alkanes detected were originally preserved in the mudstone as long-chain carboxylic acids. The origin of these molecules remains uncertain, as they could be derived from either abiotic or biological sources.

¹Markus Patzek,^2,3Yogita Kadlag,⁴Miriam Rüfenacht,⁵Evelyn Füri,⁶Andreas Pack,¹Addi Bischoff,²Harry Becker,²Robbin Visser,²Timm John,⁴Maria Schönbächler
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14343]
¹Institut für Planetologie, University of Münster, Münster, Germany
²Freie Universität Berlin, Institut für Geologische Wissenschaften, Berlin, Germany
³Physical Research Laboratory, Ahmedabad, Gujarat, India
⁴Institute of Geochemistry and Petrology, ETH Zurich, Zurich, Switzerland
⁵Université de Lorraine, CNRS, CRPG, Nancy, France
⁶Universität Göttingen, Geowissenschaftliches Zentrum, Göttingen, Germany
Published by arrangement with John Wiley & Sons

A multi-element isotope (N, O, Ti, and Cr) study was conducted on C1 and CM-like clasts hosted in achondrites and chondrite breccias to understand the genesis of these chondritic clasts. The mineralogy, O, and N isotopes confirm that CM-like clasts in howardites and polymict eucrites closely resemble CM chondrite-like material. The O and Cr isotope composition of C1 clasts in CR chondrites overlaps with those of CR chondrites, implying either formation in a similar nebular environment or resemblance to local CR material that underwent more extensive in situ alteration. Notably, these clasts are less enriched in 15N than bulk CR chondrites. In contrast, C1 clasts in ureilites are enriched in 15N relative to the Earth’s atmosphere by ~100‰ setting them apart from any other known solar system material. They display elevated 17O and 18O values and lie along the CCAM line. In addition, a C1 clast from an ureilite represents the most 54Cr-enriched and 50Ti-depleted endmember among the carbonaceous chondrites. Altogether, these isotopic characteristics suggest that C1 clasts in ureilites represent material not sampled by any known meteorite group. Overall, this study highlights the presence of primitive, isotopically distinct materials in the early outer solar system, some of which were transported to the inner solar system to the accretion region of the host parent bodies.

^1,2,3Alice Macente,^3,4,5Luke Daly,³Sammy Griffin,^6,7,8Maria Gritsevich,^6,7Jarmo Moilanen,³Josh Franz Einsle,⁹Patrick Trimby,¹⁰Chris Mulcahy,¹⁰Jonathan Moffat,¹¹Alexander M. Ruzicka
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14344]
¹School of Civil Engineering, University of Leeds, Leeds, UK
²Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, UK
³School of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK
⁴Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales, Australia
⁵Department of Materials, University of Oxford, Oxford, UK
⁶Faculty of Science, University of Helsinki, Helsinki, Finland
⁷Finnish Fireball Network, Helsinki, Finland
⁸Institute of Physics and Technology, Ural Federal University, Ekaterinburg, Russia
⁹Carl Zeiss Limited, Cambourne, UK
¹⁰Oxford Instruments Nanoanalysis, High Wycombe, UK
¹¹Department of Geology and Cascadia Meteorite Laboratory, Portland State University, Portland, Oregon, USA
Published by arrangement with John Wiley & Sons

Combining electron backscatter diffraction (EBSD) with X-ray computed tomography (XCT) offers a comprehensive approach to investigate shock deformation and rock texture in meteorites, yet such integration remains uncommon. In this study, we demonstrate the synergistic potential of XCT and EBSD in revealing deformation metrics, thereby enhancing our understanding of petrofabric strength and shock-induced deformation. Our analysis focuses on the Ozerki (L6, S4/5, W0) meteorite fall, which was instrumentally observed on June 21, 2018, and subsequently recovered by the Ural’s branch of the Russian Fireball Network (UrFU) recovery expedition a few days later. The trajectory analysis conducted by the Finnish Fireball Network facilitated the prompt retrieval of the meteorite. We show that Ozerki is deformed, with a moderate strength foliation fabric defined by metal and sulfide grain shapes. Microstructural analysis using EBSD shows that the parent body was likely still thermally active during this impact event. Our data suggest that these microstructures were likely produced during an impact while the Ozerki’s parent body was still warm.

^1,2Tianqi Zhang,^1,3Qi Tao,^1,2Xiaorong Qin,^2,4Yuchun Wu,^1,2Jiaxin Xi,^1,3Xiaoliang Liang,^1,3Hongping He,⁵Sridhar Komarneni
Journal of Geophyical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2024JE008619]
¹State Key Laboratory of Deep Earth Processes and Resources, & Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, PR China
²University of Chinese Academy of Sciences, Beijing, PR China
³CAS Center for Excellence in Deep Earth Science, Guangzhou, PR China
⁴State Key Laboratory of Solar Activity and Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, PR China
⁵Department of Ecosystem Science and Management and Materials Research Institute, 204 Energy and the Environment Laboratory, The Pennsylvania State University, University Park, PA, USA
Published by arrangement with John Wiley & Sons

Despite the anticipated abundant carbonates due to historical atmospheric CO2 levels, Mars presents a geological puzzle with MgFe-smectites dominating the Noachian and early Hesperian terrains, contrasted by sparse carbonate deposits. To address this point, we explored the impact of CO2 on MgFe-smectite formation, emphasizing the role of variable Si concentrations within the simulated Martian environment. Hydrothermal experiments, conducted under a constant CO2 concentration (C0.5) and varying Si concentrations (Si0.5 to Si4), reveal a transformation from pyroaurite to MgFe-smectite via lizardite as an intermediary phase. This transformation underscores the crucial role of Si in this mineral sequence. Notably, experiments demonstrate that the interlayer CO32− in pyroaurite is released into aqueous environments during the mineral conversion, potentially impacting the Martian CO2 budget. These findings could explain isolated carbonate outcrops and the possibility of hydrotalcite-group minerals on Mars today. Further Mars exploration should consider identifying hydrotalcite-group minerals for their implications on the planet’s climate and habitability.