¹Johannes Lier,¹Christian Vollmer,¹Linus Risthaus,^2,3Demie Kepaptsoglou,^2,4Quentin M. Ramasse,²Aleksander B. Mosberg,⁵Ashley J. King,^5,6Charlotte L. Bays,⁵Paul F. Schofield
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70027]
¹Institut für Mineralogie, Universität Münster, Münster, Germany
²SuperSTEM Laboratory, Daresbury, UK
³School of Physics, Engineering and Technology, University of York, Heslington, UK
⁴School of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, Leeds, UK
⁵Planetary Materials Group, Natural History Museum, London, UK
⁶Department of Earth Sciences, Royal Holloway, University of London, Egham, UK
Published by arrangement with JohnWiley & Sons

Samples of observed meteorite falls provide important constraints on alteration histories of Solar System materials. Due to its rapid collection, terrestrial alteration in the observed Mighei-type (CM) carbonaceous chondrite fall Winchcombe was minimal. In this work, the petrography and mineralogy of three Winchcombe lamellae, two from the matrix and one from a lithological clast, were analyzed by transmission electron microscopy. Our results demonstrate that the matrix of Winchcombe is dominated by Mg-Fe-rich serpentine-type phyllosilicates and tochilinite-cronstedtite intergrowth (TCI)-like phases with variable, but generally high (petrologic type 2.0–2.3) alteration degrees that agree with petrologic types acquired on TCIs on larger scales in other work. However, we also located pristine areas in investigated lamellae such as homogeneous amorphous silicates and glassy particles with sulfide and metal inclusions that resemble altered cometary GEMS (glass with embedded metal and sulfides). One distinct GEMS-like domain shows Fe-rich metal and sulfide grains with oxygen-enriched rims in a Mg-rich amorphous groundmass embedded in organic matter, which likely shielded it from more severe alteration. Fe-Ni-sulfides are mainly pentlandite and concentrated in matrix lamellae. In addition to the sub-μm scale brecciated texture, the three lamellae show different alteration extents, further demonstrating the complex alteration nature of this CM2 meteorite.

¹Sin-iti Sirono,²Diego Turrini
Scientific Reports 15, 30919 Open Access Link to Article [DOI https://doi.org/10.1038/s41598-025-12643-x]
¹Graduate School of Earth and Environmental Sciences, Nagoya University, Nagoya, Japan
²Turin Astrophysical Observatory, National Institute of Astrophysics (INAF), Pino Torinese, Italy

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¹Timofey Broslav, ¹Chris Dreyer, ²Joel Sercel
Acta Astronautica 235, 1-16 Open Access Link to Article [https://doi.org/10.1016/j.actaastro.2025.04.033]
¹Colorado School of Mines, 1500 Illinois St, Golden, 80401, Colorado, United States
²Trans Astronautica Corporation, 13539 Desmond St, Los Angeles, 91331, California, United States

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¹E. V. Petrova,¹V. I. Grokhovsky
Solar System Research 59, 45 Link to Article [DOI https://doi.org/10.1134/S003809462460197X]
¹Department of Physical Methods and Devices for Quality Control, Institute of Physics and Technology, Ural Federal University, 620002, Yekateringburg, Russia

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¹S. Natrajan, ¹K.K. Marhas, ²V.J. Rajesh, ¹A. Mitra
Chemical Geology 690, 122880 Link to Article [https://doi.org/10.1016/j.chemgeo.2025.122880]
¹Physical Research Laboratory, Navrangpura, Ahmedabad, 380009, Gujarat, India
²Indian Institute of Space Science and Technology, Valiyamala, Thiruvananthapuram, Kerala, India

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¹Mostafa M. A. Mohamed,¹Mohamed H. Hamza,¹Laurence A. J. Garvie,¹Desireé Cotto-Figueroa,¹Erik Asphaug,¹Aditi Chattopadhyay
Scientific Reports 15, 18348 Open Access Link to Article [DOI
https://doi.org/10.1038/s41598-025-02724-2]
¹School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ, USA
²Buseck Center for Meteorite Studies, Arizona State University, 741 East Terrace Road, Tempe, AZ, 85287-6004, USA
³Department of Physics and Electronics, University of Puerto Rico at Humacao, Call Box 860, Humacao, PR, 00792, USA
⁴Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, 85721, USA

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¹Lucas. R. Smith,¹Pierre Haenecour,¹Jessica J. Barnes,¹Kenneth Domanik,¹Yao-Jen Chang,¹Dolores Hill
The Planetary Science Journal 6, 122 Open Access Link to Article [DOI 10.3847/PSJ/adce00]
¹Lunar and Planetary Laboratory, The University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721-0092, USA

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¹L. F. White,¹B. G. Rider-Stokes,^1,2M. Anand,³R. Tartèse,⁴J. R. Darling,¹G. Degli Alessendrini,³R. Greenwood,⁵K. T. Tait
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70023]
¹School of Physical Sciences, The Open University, Milton Keynes, UK
²Department of Earth Sciences, The Natural History Museum, London, UK
³Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
⁴School of Earth, Environment and Geography, University of Portsmouth, Portsmouth, UK
⁵Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada
Published by arrangement with John Wiley & Sons

Brachinites are a group of ultramafic achondritic meteorites thought to sample a planetesimal from the early inner solar system. They yield predominately ancient crystallization ages within 4 Ma of CAI formation, and while the formation mechanism for these samples is debated, they are widely thought to be partial melt residues from a differentiated planetesimal(s). Here, we conduct a correlated microstructural (electron backscatter diffraction; EBSD), trace element, and U–Pb age (laser ablation inductively coupled plasma mass spectrometry; LA-ICP-MS) study of a unique, large phosphate mineral assemblage in brachinite Northwest Africa (NWA) 7828 to constrain the origin and evolution of this sample and its parent body. Oxygen isotope analysis of NWA 7828 yields values in agreement with other brachinites and supportive of origin from the brachinite parent body. The phosphate assemblage is >90% chlorapatite, with merrillite occurring around grain boundaries and within fractures that crosscut the larger crystal. All calcium phosphate grains are highly crystalline, with domains of chlorapatite displaying <16° of internal misorientation, with merrillite displaying a range of unique orientations. When all concordant apatite and merrillite U-Th-Pb analyses are considered together, they yield a precise weighted average 207Pb-206Pb date of 4431 ± 5 Ma suggestive of a single population recording their crystallization age. Textural, chemical, and isotopic measurements of NWA 7828 are hard to reconcile with the formation of the phosphate assemblage in an igneous environment, instead supporting a metasomatic origin. The relatively younger age of the assemblage (4431 Ma) places it outside the estimated prolonged heating period on the brachinite parent body, instead requiring a later source of energy such as through impact-induced heating. This event coincides with the timing of impacts recorded by other brachinite (and brachinite-like) meteorites, as well as impact ages recorded by some Apollo melt breccias, and suggests a widespread, significant bombardment event around 4430 Ma.

¹Cisem Altunayar-Unsalan,¹Ozan Unsalan,²Radosław A. Wach,³Marian A. Szurgot
Astrophysics and Space Science 370, 53 Link to Article [DOI https://doi.org/10.1007/s10509-025-04443-6]
¹Graduate School of Natural and Applied Sciences, Ege University, 35100, Bornova, Izmir, Turkey
Institute of Applied Radiation Chemistry, Łódź University of Technology, Wróblewskiego 15, 93-590, Łódź, Poland
²Center of Mathematics and Physics, Łódź University of Technology, Al. Politechniki 11, 90-924, Łódź, Poland

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^1,2Ke Zhu (朱柯),^3,4Bokai Dai,^3,4Xiaobin Cao,⁵Shengyu Tian,⁶Lu Chen
Monthly Notices of the Royal Astronomical Society: Letters 542, L7–L11 Link to Article [https://doi.org/10.1093/mnrasl/slaf059]
¹State Key Laboratory of Geological Processes and Mineral Resources, Hubei Key Laboratory of Planetary Geology and Deep-Space Exploration, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
²Bristol Isotope Group, School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen’s Road, Bristol BS8 1RJ, UK
³International Center for Isotope Effects Research, Nanjing University, Nanjing 210023, China
⁴State Key Laboratory of Critical Earth Material Cycling and Mineral Deposits, Frontiers Science Center for Critical Earth Material Cycling, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
⁵Max Planck Institute for Solar System Research, Göttingen 37077, Germany
⁶Wuhan SampleSolution Analytical Technology Co. Ltd, Wuhan 430000, China

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