^1,2Ninja Braukmüller, ^1,3Claudia Funk, ^1,5Wafa Abouchami, ⁴Harvey Pickard, ⁴Mark Rehkämper, ^1,6Alessandro Bragagni, ⁵Stephen J.G. Galer, ¹Carsten Münker, ²Harry Becker, ¹Frank Wombacher
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.02.001]
¹Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49b, 50674 Köln, Germany
²Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstr. 74-100, 12249 Berlin, Germany
³Steinmann Institut für Geologie, Mineralogie und Paläontologie, Universität Bonn, Poppelsdorfer Schloss, 53115 Bonn, Germany
⁴Department of Earth Science & Engineering, Imperial College London, London SW7 2AZ, UK
⁵Max-Planck-Institut für Chemie, Hahn-Meitner-Weg 1, 55128 Mainz, Germany
⁶Dipartimento di Scienze della Terra, Università degli Studi di Firenze, via La Pira 4, 50121 Firenze, Italy
Copyright Elsevier

Most chondrites are depleted in moderately volatile elements (MVE) relative to the bulk solar system composition represented by CI chondrites. Here we present high-precision isotope dilution data for 11 moderately volatile elements (S, Cu, Zn, Ga, Se, Ag, Cd, In, Sn, Te and Tl) together with Cd and Zn stable isotope compositions for carbonaceous, ordinary, enstatite and Rumuruti chondrites complemented by a literature compilation of MVE stable isotope compositions. Together these data allow new insights into the processes that led to MVE depletion in chondrites and their redistribution within parent bodies.
Moderately volatile element abundances in carbonaceous, ordinary and Rumuruti chondrites are best explained by two-component mixing between a chemically CI-like MVE-rich matrix and an MVE-poor refractory component dominated by chondrules. Chondrules are enriched in light MVE isotopes due to kinetic recondensation of a small vapor fraction initially lost from chondrules upon heating. Later, thermal metamorphism redistributed some MVE within chondrite parent bodies, which is evaluated here in a systematic way for different chondrite groups and plateau volatile elements based on related and comparatively large but unsystematic stable isotope fractionation. Compared to other chondrite classes, enstatite chondrites show less systematic MVE abundance patterns when the elements are plotted as a function of condensation temperatures. Type 3 and 4 enstatite chondrites are more MVE-rich than expected based on their low matrix fractions and are enriched in light Zn and Te isotopes relative to CI. The enrichment of light Zn and Te isotopes and high MVE abundances in type 3 and 4 enstatite chondrites relative to CI can be explained by recondensation of a larger MVE vapor fraction after chondrule formation than observed for other chondrite classes, which presumably occurred at comparatively high H2 pressures. Because MVE abundances and isotope compositions are fully consistent with chondrule formation, two-component mixing and MVE redistribution on parent bodies, we refute partial condensation from a hot solar nebula as the cause for MVE depletion in chondrite formation regions of the protoplanetary disk.

¹Artem Y. Burdanov et al. (>10)
Nature 638, 74-78 Link to Article [DOI https://doi.org/10.1038/s41586-024-08480-z]
¹Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA

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^1,2,3Jun Zhang et al. (>10)
Earth and Planetary Science Letters 654, 119239 Link to Article [https://doi.org/10.1016/j.epsl.2025.119239]
¹Key Laboratory of Mountain and Surface Process, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China
²State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China
³University of Chinese Academy of Sciences, Beijing 100049, China
Copyright Elsevier

Grain size distribution (GSD) is crucial for understanding soil properties and surface processes. We find that both terrestrial soils and lunar soils are subjected to a unified GSD function, P(D)= g(μ)D-μexp(-D/Dc), reducing the textural fractions and grade modes to a parameter pair (μ, Dc), which unifies terrestrial and extraterrestrial soils in granular configuration, beyond the environments and mechanisms of soil genesis. To construct a framework of the soil formation, we generalize the textural composition to a grade space representing the granular configuration, and conceptualize soil genesis as the random aggregation of the fractal fragmentation of parent lithospheric material and fragments from other sources (e.g., meteorites impacts or surface transport processes). Random simulation reproduces the multiple grade modes observed in soils, and spontaneously derives the unified GSD function. Then we numerically generate the (μ, Dc)-fields for soils on earth and moon, which refine the digital data mapping based on site measurements and depict the local fluctuation of soil parameters. The GSD unity also provides a tool of generating “numerical simulants” of lunar soils to fill the gap in material simulants. The study leads to a GSD-paradigm (in contrast to the conventional landscape-paradigm) in soil study, which is expected to facilitate the data harmonization on earth and promote the generation of lunar regolith data in favor of the in-situ resource utilization and base construction on moon.

¹Daniel O. Cukierski,¹David W. Peate,^1,2Ingrid A. Ukstins,¹Christy Kloberdanz,¹C. Tom Foster,^1,3Chungwan Lim
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14322]
¹Department of Earth & Environmental Sciences, University of Iowa, Iowa City, Iowa, USA
²School of Environment, The University of Auckland, Auckland, New Zealand
³Department of Earth Science Education, Kongju National University, Kongju, Chungnam, Republic of Korea
Published by arrangement with John Wiley & Sons

Samples of impactite from the small (~350 m diameter) Monturaqui crater in northern Chile contain Fe-Ni metallic spherules sourced from the iron meteorite impactor. Textural characterization and quantification were done using SEM and μCT data. Two textural types are distinguished, with different size distributions. The smaller spherical objects (mostly <100 μm in diameter) follow a power law size distribution, while larger objects are mostly irregular-shaped patches. These are analogous to the small (nm to 50 μm) immiscible spherical metal droplets and large (150–500 μm) irregular partly fused pieces of the iron meteorite projectile observed in highly shocked ejecta fragments during hypervelocity impact experiments. Compositions of both spherule types were determined using in situ methods (electron microprobe, LA-ICP-MS), as well as solution ICP-MS on individual spherules separated from impact melt glass using electric pulse disintegration. Spherules are enriched in Ni and Co relative to Fe and W and relative to the inferred iron meteorite impactor composition, and PGEs show similar enrichments with limited fractionation between different PGEs, all consistent with selective oxidation processes. All spherules have similar chondrite-normalized patterns that are also broadly similar to weathered fragments of the iron meteorite impactor. Ni-Ge and Ni-Ir data on large (>300 μm) spherules and weathered meteorite fragments suggest that the Monturaqui impactor was a group IAB iron meteorite.

¹Martin R. Lee,¹Cameron J. Floyd,¹Robin Haller,¹Sammy Griffin
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14310]
¹School of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK
Published by arrangement with John Wiley & Sons

Xenoliths in carbonaceous chondrites include lithologies that are unrepresented in the meteorite record and so are a rich source of information on asteroid diversity. Cold Bokkeveld is a CM2 regolith breccia that contains both hydrous and anhydrous lithic clasts. Here, we describe a hydrous clast with a fine-grained rim. This rim shows that the clast is a xenolith that interacted with dust in the protoplanetary disk between liberation from its protolith and incorporation into Cold Bokkeveld’s parent body. Prior to its fragmentation, the xenolith’s protolith had undergone brittle deformation, with the fractures produced being cemented by carbonates to make veins. After being incorporated into Cold Bokkeveld’s parent body, the veined xenolith experienced a second phase of aqueous alteration leading to hydration of its fine-grained rim, replacement of carbonate by tochilinite–cronstedtite intergrowths, and formation of magnetite within its fine-grained matrix. The veined xenolith’s protolith underwent its entire geological evolution (accretion–aqueous alteration–fracturing–fragmentation) before Cold Bokkeveld’s parent body had accreted. Such a short lifespan may be explained by explosive breakup of the protolith due to overpressure from gases produced internally during water–rock interaction. Early fragmentation effectively acted as a thermostat to limit runaway heating that may have otherwise resulted from the body’s high concentrations of 26Al. Many other hydrous lithic clasts in CM carbonaceous chondrite meteorites could be the remains of such ephemeral early asteroids, but they are hard to identify without evidence that they were accreted as hydrous lithologies and contemporaneously with chondrules.

¹Lulu Zhao,¹Anbei Deng; Hanlie Hong,²Jiannan Zhao,^1,3,4Thomas J. Algeo,¹Fuxing Liu,⁵Nanmujia Luozhui,¹Qian Fang
American Mineralogist 110, 217-231 Link to Article [https://doi.org/10.2138/am-2023-9299]
¹State Key Laboratory of Biogeology and Environmental Geology, Hubei Key Laboratory of Critical Zone Evolution, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
²Key Laboratory of Geological Survey and Evaluation of Ministry of Education, China University of Geosciences, Wuhan 430074, China
³Department of Geosciences, University of Cincinnati, Cincinnati, Ohio 45221-0013, U.S.A.
⁴State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China
⁵Military-Civilian Integrated Geological Survey Center, China Geological Survey, Lhasa 850006, China
Copyright: The Mineralogical Society of America

Clay minerals are common in martian geological units and are globally widespread on Earth. Understanding the origin, formation, and alteration of clay minerals is crucial for unraveling past environmental conditions on Earth and Mars, in which the composition and crystallinity of clay minerals serve as important surrogate indicators for addressing these issues. Here, 621 soil and sediment samples from five chronosequences representing different climatic zones of China were investigated using visible to near-infrared reflectance (VNIR) in combination with X-ray diffraction (XRD) analysis. The crystallinity of clay minerals (i.e., illite crystallinity, illite chemistry index, kaolinite crystallinity) and clay mineral alteration index (CMAI) were analyzed with conventional methods and then predicted through a spectral modeling approach. Our results show that kaolinite with a pedogenic or sedimentary origin is characterized by a broad crystallinity range and a poorly ordered structure, especially when generated in an intense weathering environment. Predictive models were constructed with data-mining methods, including partial least-squares regression (PLSR), random forest (RF), and Cubist algorithms. The predictive performance of the crystallinity and CMAI proxies is robust, with an overall accuracy of 78% and a residual prediction deviation (RPD) of 2.57. We also found that the model’s accuracy in predicting clay-mineral-related proxies increased by 45% using random forest (RF) and Cubist compared to the PLSR models. We suggest that VNIR spectroscopy combined with RF and Cubist methods has the potential to be an alternative and broadly applicable tool for analyzing typical clay-mineral proxies, substituting for a series of common mineralogic analyses. Spectral modeling can reveal genetic and climatic information at both field and regional scales, which has profound implications for Mars missions and other space exploration programs.

^1,2Mélissa Martinot,¹Kerri L. Donaldson Hanna,³Benjamin T. Greenhagen,¹Luis Santori,³Patrick N. Peplowski,³Joshua T. S. Cahill
The Planetary Science Journal 6, 20 Open Access Link to Article [DOI 10.3847/PSJ/ad94f0]
¹Department of Physics, University of Central Florida, 4111 Libra Drive, Orlando, FL 32816, USA
²CRPG, CNRS/Université de Lorraine, Vandœuvre-lès-Nancy, France
³The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA

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¹Peter Wurz,¹Noah Jäggi,¹André Galli,¹Audrey Vorburger,²Deborah Domingue,³Paul S. Szabo,⁴Johannes Benkhoff,⁵Océane Barraud,⁶Daniel Wolf Savin
The Planetary Science Journal 6, 24 Open Access Link to Article [DOI 10.3847/PSJ/ad95fa]
¹Space Science and Planetology, Physics Institute, University of Bern, Bern, Switzerland
²Planetary Science Institute, Tucson, AZ, USA
³Space Sciences Laboratory, University of California, Berkeley, CA, USA
⁴ESA/ESTEC, Noordwijk, The Netherlands
⁵German Aerospace Center (DLR)—Institute of Planetary Research, 12489 Berlin, Germany
⁶Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA

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^1,2Jean Charlier,¹Alice Aléon-Toppani,¹Rosario Brunetto,²Jérôme Aléon,³Ferenc Borondics
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14314]
¹Institut d’Astrophysique Spatiale, CNRS, Université Paris-Saclay, Orsay, France
²Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, Museum National d’Histoire Naturelle, CNRS UMR 7590, IRD, Paris, France
³SOLEIL Synchrotron, L’Orme des Merisiers, RD 128, Saint Aubin, France
Published by arrangement with John Wiley & Sons

Refractory inclusions (RIs) in chondrites are widely used as tracers of early solar system formation conditions. In the context of sample-return missions, a non-destructive and non-invasive analytical tool that can rapidly detect and characterize RIs in space samples during their early phase of study is highly needed. Here, we performed mid-infrared (MIR) fine-scale hyperspectral imaging over large fields of view to detect RIs in CM and CO chondrites. A database of MIR spectra of typical RIs minerals was built (1) to support future remote sensing observations in astronomical environments and (2) to develop a detection method based on machine-learning algorithms and spectral distance between sample and reference minerals. With this method, up to 96.5% of the RI content is detected in a meteorite section. Further comparison between scanning electron microscopy and spot analysis acquired in reflectance in the full MIR range shows that RIs can be classified following their mineralogy based on infrared (IR) properties. Finally, we show that the relative OH content of several RIs in CM chondrites determined from IR spectroscopy can be used to infer the extent of modification caused by aqueous alteration on the asteroidal parent body.

^1,2,3Juliane Gross et al. (>10)
Journal of Geophysical Research (Planets)(in Print) Link to Article [https://doi.org/10.1029/2024JE008585]
¹Astromaterials Acquisition and Curation Office, NASA Johnson Space Center, Houston, TX, USA
²Lunar and Planetary Institute, Houston, TX, USA
³Department Earth and Planetary Sciences, The American Museum of Natural History, New York, NY, USA
Published by arrangement with John Wiley & Sons

During the six Apollo missions, astronauts collected 2196 lunar samples, nearly all of which have been studied over the past five decades. Six Apollo samples remained unexamined until 2019 and were saved to be analyzed by the next generation of lunar scientists using advanced modern laboratory facilities. Now more than 50 years after Apollo, NASA is returning to the Moon with Artemis and will return geologic samples from a different region of the lunar surface than Apollo. Curation will play an instrumental role in helping to prepare for the safe return of these valuable samples, ensuring their integrity during all stages of the missions, and thus maximizing their scientific return. To prepare for the return of these samples, NASA initiated the Apollo Next Generation Sample Analysis (ANGSA) Program to open previously unstudied samples including unopened double drive tube 73002 and 73001 (also vacuum-sealed) from the Apollo 17 mission to the Taurus-Littrow Valley. The ANGSA program was designed to function as a low-cost analog sample return mission and served as a testing ground to understand processes, update techniques, and prepare for the preliminary examination (PE) of the to-be-returned lunar samples with Artemis. New and advanced curation techniques were developed and applied to support the analyses of 73002/73001 during the PE. Furthermore, cutting-edge analytical instruments such as X-ray Computed Tomography were utilized to aid in PE that were unavailable during Apollo. These efforts are equipping the Artemis generation for future lunar missions and lessons learned from the PE of ANGSA samples will be directly applied to Artemis.