¹Hikaru Hyuga,¹Yuichiro Cho,¹Yayoi N. Miura,¹Takashi Mikouchi,^1,2Seiji Sugita
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70022]
¹Department of Earth and Planetary Science, University of Tokyo, Bunkyo, Japan
²Planetary Exploration Research Center, Chiba Institute of Technology, Narashino, Japan
Published by arrangement with John Wiley & Sons

Dating rocks with a 2σ precision of 200 Ma is required to understand the history of Martian habitability and volcanic activity since ~4000 Ma. In situ K-Ar dating using a spot-by-spot laser ablation technique has been developed for isochron dating on Mars. The precision of isochron ages is determined mainly by the relationship between the laser spot diameter and the grain size of the sample. However, the achievable precision of age estimates using a realistic mineralogy of Martian rocks has yet to be investigated. We simulated isochrons under various conditions, including different laser spot sizes, K and Ar measurement errors, and numbers of analyses based on the mineral abundances of representative Martian meteorites (NWA 817, Zagami, and NWA 1068) analyzed using an electron probe microanalyzer. We found that attaining a precision of 200 Ma necessitates an isochron data range, defined as the ratio of the maximum to minimum K concentrations, of >6, a laser spot diameter of 250 μm, and measurement errors of <10% for both K and Ar. Reducing the laser spot size and selecting a sample with a large grain size are effective in obtaining a large K range. Furthermore, minimizing the variance in measurement errors between K and Ar is essential to increase the accuracy of the age estimates. We demonstrate that the precision required for in situ dating on Mars is achievable with realistic instrument settings, thus demonstrating the feasibility of establishing an in situ K-Ar geochronology for Mars.

¹Mohammad Tauseef,¹Ingo Leya,²Beda Hofmann
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70029]
¹Space Research and Planetary Sciences, Physics Institute, University of Bern, Bern, Switzerland
²Natural History Museum Bern, Bern, Switzerland
Published by arrangement with John Wiley & Sons

We present isotope concentrations of the light noble gases He and Ne for samples from five well-documented strewnfields and two individual meteorites from the Omani desert. Cosmogenic (22Ne/21Ne)cos for the strewnfield samples are low, as expected considering the total known masses. A (22Ne/21Ne)cos of 1.210 for the LL6 chondrite RaS 267 from Oman indicates a small pre-atmospheric size of less than 10 cm. The CRE ages for the Omani meteorites calculated using 21Necos range from 1 to 20 Ma. Using the (22Ne/21Ne)cos and previously established correlations, new shielding-corrected 14C and 14C-10Be terrestrial ages are calculated. For the strewnfield samples, the new ages are similar to the earlier ages but are more consistent. The new terrestrial age for RaS 267 is more than 20% lower than the previous age. Motivated by this success, we reinvestigated meteorites from other hot deserts (Acfer, Adrar, and Nullarbor regions) and Antarctica using literature data for 14C and (22Ne/21Ne)cos, along with the newly established correlations between 14C production rates and (22Ne/21Ne)cos. For these meteorites, the new terrestrial ages are systematically younger than the ages calculated earlier using a shielding-independent approach. Using shielding-corrected 14C terrestrial ages, the long-term puzzling problem that there is a lack of meteorites with short terrestrial ages disappears. The new histogram, though with only a limited number of data, shows the expected decrease in the number of meteorites with increasing terrestrial age. Therefore, the unexpected shape in the terrestrial age histogram was most likely due to a bias in the 14C dating system, that is, ages of small meteorites are overestimated.

¹Pascal M. Kruttasch,¹Klaus Mezger
Science Advances 11, eadw1280 Open Access Link to Article [DOI: 10.1126/sciadv.adw12]
¹Institut für Geologie, Universität Bern, 3012 Bern, Switzerland.

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

^1,2,3Laura Noel García,^4,5Péter Némenth,⁶Ronan Henry,⁷Robert Luther,^1,2Maria Eugenia Varela
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70024]
¹Instituto de Ciencias Astronómicas, de la Tierra y del Espacio, Universidad Nacional de San Juan, CONICET, San Juan, Argentina
²Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, San Juan, Argentina
³Instituto de Mecánica Aplicada, Universidad Nacional de San Juan, San Juan, Argentina
⁴Institute for Geological and Geochemical Research, HUN-REN Research Centre for Astronomy and Earth Sciences (MTA Centre of Excellence), Budapest, Hungary
⁵Research Institute of Biomolecular and Chemical Engineering, University of Pannonia, Veszprém, Hungary
⁶Groupe de Physique des Matériaux, UMR CNRS 6634, Saint Etienne du Rouvray, France
⁷Museum für Naturkunde Berlin-Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany
Published by arrangement with John Wiley & Sons

Cliftonites, polycrystalline aggregates of graphite with unusual cuboid morphology, are important carbon components of certain iron meteorites. Although they consist predominantly of sp2-bonded carbon, recent studies suggest that those from the Canyon Diablo (IAB) meteorite also include composite sp2- and sp3-bonded structures, named diaphites. Here, we investigate the nanostructure of cliftonites in a Campo del Cielo specimen and demonstrate that these cliftonites also contain a nanocomposite mixture of well-ordered 3R graphite regions interfingered with type 1 diaphite structure, consisting of <01–10> projected graphite and <011> projected diamond domains. This finding suggests that certain pieces of the Campo del Cielo meteorite experienced moderate shock pressures (>~10 GPa), which exceed the 4–10 GPa pressure range previously reported for the main meteorite. We propose that a portion of Campo del Cielo cliftonites provides evidence for the shock-induced diamondization of graphite and the “projectile decapitation” process during terrestrial impact. The complexity of the initial carbonaceous material, combined with the wide range of pressures encountered during terrestrial impact events, may explain the diversity of nanostructures in the Campo del Cielo and Canyon Diablo cliftonites. Our findings could assist in the development of a pressure/shock classification system for characterizing impact events in graphite-bearing meteorites.

^1,2,3Haiyang Xian et al. (>10)
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.epsl.2025.119556]
¹State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China
²Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China
³Center for Advanced Planetary Science (CAPS), Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China
Copyright Elsevier

Recent discoveries regarding oxidized materials on the moon have challenged the traditional belief that the moon is highly reduced. The oxidized materials occur in either crystalline minerals or glasses, and the complex occurrence makes the origin of these oxidized lunar materials still unclear. Here we report a highly oxidized impact melt clast retrieved by Chang’e 6 mission from the South Pole-Aitken (SPA) basin. The impact melt clast hosts a high content of ferric iron (Fe³⁺) in matrix pigeonite with an Fe³⁺/∑Fe ratio of 0.44 ± 0.06, while xenocryst pyroxene only contains ferrous (Fe²⁺) iron. The observed high Fe³⁺ content indicates that the oxidation state of the local impact clast is even more oxidized than that of Earth’s mantle. The widespread presence of non-spherical Fe-Ni alloy nanoparticles in the impact melt clast suggests that the oxidized materials may have been delivered to the moon by meteorite. These findings reveal an external source of oxidized materials on the moon, emphasizing the potential role of meteoritic materials in the redox cycling of the lunar surface.

¹Zhengyang Wu, ¹Chang Pu, ¹Xiujin Gao, ¹Jinfeng Li, ²Zhixue Du, ¹Zhicheng Jing
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.07.024]
¹Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen 518055, China
²State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
Copyright Elsevier

Gallium (Ga) and germanium (Ge) are moderately siderophile and volatile elements whose metal-silicate partitioning behaviors are valuable to understand both core-formation and volatile accretion processes. In this study, we performed metal-silicate partitioning experiments at pressures of 22–70 GPa and temperatures of 3728–4740 K, using laser-heated diamond anvil cells, to explore the effects of pressure, temperature, and metal composition on Ga and Ge partitioning. Thermodynamic modeling using our experimental data and those from the literature reveals that the metal affinities of both Ga and Ge decrease as pressure and temperature increase, with Ga being less siderophile than Ge. Our fitting results confirm that the presence of S and Si in metal can reduce the siderophility of both Ga and Ge, consistent with previous findings at relatively low pressures and temperatures. Our results also demonstrate that O in metal has opposing effects on the metal-silicate partitioning of Ga and Ge. It increases the metal affinity of Ga, contrary to previous thought, but decreases that of Ge. Incorporating these partitioning behaviors, we performed multi-stage core formation modeling to search for accretion scenarios and factors that can reproduce the bulk silicate Earth abundances of Ga, Ge, and S. Our results suggest that Ga and Ge were likely accreted throughout the entire stages of Earth’s accretion rather than accreted solely in the late stage for the final 10–20 % of Earth’s mass growth.

¹Krämer Ruggiu Lisa, ²Villeneuve Johan, ³Da Silva Anne-Christine, ⁴Debaille Vinciane, ⁵Decrée Sophie, ⁶Lutz Hecht, ⁶Felix E.D. Kaufmann, ¹Goderis Steven
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.07.016]
¹Archaeology, Environmental Changes & Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
²CRPG, CNRS, Université de Lorraine, UMR 7358, Vandoeuvre-lès-Nancy 54501, France
³SediCClim Laboratory, Geology Department, Liège University, Liège, Belgium
⁴Laboratoire G-Time, Université Libre de Bruxelles, Brussels, Belgium
⁵Institute of Natural Sciences, Geological Survey of Belgium, Brussels, Belgium
⁶Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrasse 43, Berlin 10115, Germany
Copyright Elsevier

A total of 1222 Micrometeorites (MMs) from the late Devonian period were extracted from 26 kg of carbonates host rock fragments from the Chanxhe section in Belgium, from the Latest Famennian around 360 Myr, through magnetic separation and optical picking following dissolution with mild HCl, making it one of the largest fossil MMs collection, the largest from the late Devonian. The collection shows a wide diversity of texture, comparable to modern day collection but with different distribution. The majority of the MMs were I-type (90 %), with G-type particles constituting 6 % and S-type particles at 1 %. Some of the S-types spherules are amongst the first silicate-type spherules, and amongst the most well-preserved in terms of texture and composition, to be described in fossil MMs collections. Additionally, intermediate type G/I representing <1 % of the sample are introduced for future fossil MMs classification. Distinguishing extraterrestrial (ET) MMs from terrestrial spherules is challenging due to weathering effects that modify both texture and composition during long residency time on Earth. The Na2O + K2O versus Fe/Si ratio plot is used for distinguishing ET from terrestrial spherules. Using textural and compositional data in combination creates a reliable ET spherule identification. I-type spherules show significant terrestrial alteration with notable loss of Ni and Cr, also observed in S-type spherules, with their silicate phases recrystallized in palagonite. G-type spherules display a mix of characteristics from I-type and S-type MMs. The study also highlights the presence of smaller spherules (<125 µm) compared to modern micrometeorites (210–330 µm), attributed to the predominance of I- and G-type spherules and long-term dissolution effects. Despite some alteration for some spherules, due diagenesis of the sedimentary host rocks, the collection shows extremely well-preserved spherules, with even some oxygen isotopes signature being preserved. Indeed, triple oxygen isotope analysis reveals that 5.8 % of the particles are related to ordinary chondrites (OC) and 33 % to carbonaceous chondrites (CCs), yielding a CC/OC ratio of approximately 5.6, with comparable distribution for all major types. Also, 9 % of I- and G/I-types are OC-related. Most I-type spherules likely originate from CM, CR, or H chondrites, with some possibly from iron meteorites. The findings suggest that the source materials of the ET flux have remained relatively consistent over the past 360 Myr, providing insights into historical Solar System events and Earth’s environmental changes and extends the study of ET flux to Earth to CC compared to meteorites. In addition, combined with chemical and isotopic proxies and chrome spinel, the fossil MMs could assess the complete flux of cosmic dust to Earth. Finally, the use of fossil MMs could represent potential proxies for paleo-atmospheric oxygen levels and CO2 contents.

^1,2,3Giovanni Pratesi et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70025]
¹Dipartimento di Scienze della Terra, University of Firenze, Florence, Italy
²Fondazione PARSEC, Prato, Italy
³INAF—Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Published by arrangement with John Wiley & Sons

On the evening of February 14, 2023, at 17:58 UT, a fireball was detected by three cameras of the Italian PRISMA network (FRIPON network). The first samples of the Matera meteorite, collected 3 days after the fall, lay on the balcony of a private home. Meanwhile, four samples weighing more than 10 g (including the main mass of 46.21 g) and many minor samples (less than 10 g each) were recovered, with a total mass of 117.5 g. The analyses show that Matera is a monomict chondrite breccia, exhibiting no weathering (W0) and shock (S1). Based on the mineral compositions of olivine and low-Ca pyroxene (Fa_18.0±0.3 and Fs_17.0±0.3, respectively), the rock is an H-group ordinary chondrite. Since all low-Ca pyroxene is orthoenstatite, an H5-type classification is appropriate; although texturally, a type 4 classification could be assigned to distinct portions of the rock with well-defined chondrules. The analyzed oxygen isotopes also align with an H chondrite (δ¹⁷O‰ = 2.750 ± 0.051; δ¹⁸O‰ = 4.036 ± 0.103; Δ¹⁷O‰ = 0.650 ± 0.004). X-ray tomography and a structured light 3D scanner yielded a mean bulk density of 2.87 ± 0.04 g cm⁻³, whereas ideal gas pycnometry yielded grain densities of 3.47 ± 0.05 g cm⁻³, resulting in a porosity of 17.2 ± 1.2 vol%. The magnetic susceptibility of this meteorite is log χ = 5.46 ± 0.05. The radionuclides and fireball observations suggest that the Matera meteoroid was relatively small (with a maximum radius of 20 cm, though more likely around 15 cm). This datum is also consistent with (²¹Ne/²²Ne)_cos, which suggests the origin of Matera samples from the uppermost cm of a small meteoroid, ≤10 cm radius. Different from many other H chondrites, the transfer time in space for Matera, based on 3 He alone, is 10–12 Ma. Moreover, the Matera meteorite does not contain solar wind gases. In conclusion, the Matera meteorite is not a fairly typical ordinary chondrite, due to its low bulk density and high total porosity. The presence of ordinary chondrites with these physical characteristics must be taken into account during the asteroid modeling process, as in the case of the Didymos–Dimorphos binary system.

^1,2Laura E. Jenkins,¹Martin R. Lee,^1,3,4Luke Daly,⁵Ashley J. King,¹Peter Chung,¹Sammy Griffin,⁶Shijie Li
The American Mineralogist 110, 1238-1248 Link to Article [https://doi.org/10.2138/am-2024-9389]
¹School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, U.K.
²Diamond Light Source, Harwell Science and Innovation Campus, Fermi Avenue, Didcot OX11 0DE, U.K.
³Australian Centre for Microscopy and Microanalysis, University of Sydney, Camperdown, New South Wales 20250, Australia
⁴Department of Materials, University of Oxford, Oxford OX1 3PH, U.K.
⁵Planetary Materials Group, Natural History Museum, London SW7 5BD, U.K.
⁶Lunar and Planetary Science Research Center, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
Copyright: The Mineralogical Society of America

A hydrous Ca-Fe-rich silicate identified as hydroandradite was observed in the “Mighei-type” carbonaceous (CM) chondrite falls, Shidian and Kolang. This is the first report of hydroandradite occurring within meteorites. Hydroandradite forms through aqueous calc-silicate alteration under specific fluid conditions. Its presence within Shidian and Kolang has implications for interpreting alteration processes within the C-complex asteroid parent bodies of the CM chondrites. To better understand its occurrence, the meteoritic hydroandradite was studied with scanning electron microscopy, electron probe microanalysis, transmission electron microscopy, and Raman spectroscopy. It occurs in four petrographic contexts: layered, perovskite-associated, sulfide-associated, and spheroidal. Kolang has all four morphologies, while only the sulfide-associated occurs in Shidian. In Kolang, hydroandradite was likely produced by replacement of kamacite, Ti-bearing clinopyroxene in calcium- and aluminum-rich inclusions, and secondary magnetite in three distinct alteration events. The formation temperature of meteoritic hydroandradite was estimated to be 100–245 °C, based on the mineralogy of the lithologies within which it occurs as well as on its degree of hydration relative to synthetic and terrestrial hydroandradites. Because Kolang and Shidian are the only reported meteorites with hydroandradite to date, they may be from the same parent body.

¹Simon Stapperfend,²Donald B. Dingwell,²Kai-Uwe Hess,³Jennifer Sutherland,⁴Axel Müller,²Dirk Müller,²Michael Eitel,¹Julian Baasch,¹Stefan Linke,¹Enrico Stoll
American Mineralogist 110, 1171-1185 Open Access Link to Article [https://doi.org/10.2138/am-2023-9263]
¹Chair of Space Technology, Technische Universität Berlin, Marchstr. 12-14, 10587 Berlin,
Germany
²Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstraße 41/III, 80333 München, Germany
³Institut Laue-Langevin, 71 Av. des Martyrs, 38000 Grenoble, France
⁴OHB System AG, Manfred-Fuchs-Str. 1, 82234 Weßling, Germany
Copyright: The Mineralogical Society of America

In the context of evaluating lunar construction options, this study focuses on characterizing the viscosities and glass transition properties of lunar regolith simulants to support the development of additive manufacturing processes using molten regolith. Employing the modular TUBS lunar regolith simulant system, we measured the viscosities of different simulants through high-temperature experiments conducted between 1051 and 1490 °C using concentric cylinder viscometry in air. Additionally, differential scanning calorimetry (DSC) was utilized to evaluate the glass transition temperatures, which were in the range between 689 and 815 °C. The measured viscosity data were parameterized by the Vogel-Fulcher-Tammann (VFT) equation, which is adept at describing the viscosities and related properties of silicate liquids. The measured viscosities were compared with the predicted values of six viscosity models. The model by Sehlke and Whittington (2016) best predicts the viscosities of the tested lunar regolith simulants at superliquidus temperatures, and no model adequately predicts viscosities at the glass transition temperature, indicating a need for further research in this area. We infer that 3D printing technologies based on molten lunar regolith are, viscosity-wise, best constrained to highland regions. The reduced environment on the Moon influences the 3D printing process in a positive manner.