¹Jared M. Long-Fox, ¹Humberto Campins, ¹Daniel T. Britt
Planetary and Space Science 270, 106229 Open Access Link to Article [https://doi.org/10.1016/j.pss.2025.106229]
¹University of Central Florida Department of Physics, 4111 Libra Drive Room 430, Orlando, FL, 32816, USA

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¹J.M. Comellas et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2025.116902]
¹University of Hawai‘i at Mānoa, 2500 Campus Rd, Honolulu, 96822, HI, USA
²Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, 87545, NM, USA
Copyright Elsevier

Manganese plays a crucial role as a paleo-environmental and geological indicator due to its sensitivity to redox potential and pH variations in the environment. On Earth, the association between the rise of atmospheric oxygen during the Great Oxidation Event and the presence of Mn in the sedimentary rock record underscores its significance. In this study, we reexamined ChemCam targets from the first 600 sols of the Mars Science Laboratory mission, focusing on identifying instances of above-average Mn within these targets. These elevated-Mn targets were categorized into distinct geologic classes, revealing a pattern linking heightened Mn levels with diagenetically altered materials, such as calcium sulfate veins and concretions, as well as clay minerals within the same targets, indicating a compelling relationship between Mn enrichment and diagenetic processes. High concentrations of Mn were observed in chemically altered targets, suggesting the occurrence of multiple fluid events: the first to alter the material and the second to deposit Mn. The observed patterns suggest multiple diagenetic events and redox cycling that facilitated the deposition and transport of Mn subsequent to the initial dissolution of basaltic materials. This research sheds light on the complexity of martian diagenetic processes and their implications for the planet’s environmental evolution.

^1,2,3C. J. Gimar et al. (>10)
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009304]
¹Department of Physics and Astronomy, Univeristy of Texas at San Antonio, San Antonio, TX, USA
²Center for Laboratory Astrophysics and Space Science Experiments (CLASSE), Space Science Division, Southwest Research Institute, San Antonio, TX, USA
³Space Science Division, Southwest Research Institute, San Antonio, TX, USA
Published by arrangement with John Wiley & Sons

Building on our previous studies of the far-ultraviolet (FUV) reflectance of Apollo soil 10084 and lunar soil simulants JSC-1A and LMS-1 (Gimar et al., 2022, https://doi.org/10.1029/2022je007508; Raut et al., 2018, https://doi.org/10.1029/2018je005567), we present new FUV results for Apollo soils 68501 and 71061. Heavily weathered soils (68501, 10084)–enriched in submicroscopic Fe, agglutinates, and sub-micron scale roughness as revealed by our electron microscopy investigations–are darker in the FUV and predominantly backscatter incident light. In contrast, the relatively less weathered subsurface 71061 soil is approximately twice as bright, exhibits forward scattering, and presents a steeper blue spectral slope between 130 and 160 nm compared to the weathered soils. Differences in either primary composition or mineralogy appear to have little to no effect on the FUV albedo or scattering behavior of these soils since the reflectance of high-Ti mare 10084 and low-Ti highland 68501 are nearly indistinguishable within error. Further investigation of additional Apollo-era soils across various maturity indices is needed to fully characterize the influence of space weathering on lunar soil FUV spectrophotometric response.

¹O. Beyssac et al. (>10)
Earth and Planetary Science Letters 675, 119746 Open Access Link to Article [https://doi.org/10.1016/j.epsl.2025.119746]
¹Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR 7590, Muséum National d’Histoire Naturelle, Sorbonne Université, 75005 Paris, France
Copyright: Elsevier

Based on observation and data from meteorites and in situ scientific missions, experiments as well as models, the Martian mantle is assumed to share some compositional and mineralogical affinity with the terrestrial mantle. However, there might be subtle differences like the Martian mantle being more ferroan. Yet, we do not have any direct analysis of a Martian mantle rock to confirm this assumption. NASA’s Perseverance rover found olivine-rich boulder-sized float rocks on the upper Jezero fan (Mars). These boulders have an ultramafic composition and their mineralogy is dominantly composed of Fo73±3 olivine with high-Mg orthopyroxene, Cr-rich Ti-Fe oxides and minor plagioclase and high-Ca pyroxene. Microtextural and petrological analysis reveals that these minerals crystallized at equilibrium. In addition, these boulders are different from all the bedrocks analyzed by Perseverance along its traverse which are crustal igneous rocks and sediments. Comparing our data to Martian meteorites and available Mars bulk silicate models (BSM), we discuss that these boulders could represent primitive melts and/or lower crustal material, and we specifically hypothesize that they could be mantle peridotites. We propose that these putative mantle rocks could have been excavated by the succession of impacts from the shallow mantle or lower crust in the Isidis region where Jezero crater is located. These olivine-rich boulders could thereby constitute the first direct analysis of a Martian mantle rock.

^1,2Alan E. Rubin
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70080]
¹Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California, USA
²Maine Mineral & Gem Museum, Bethel, Maine, USA
Published by arrangement with John Wiley & Sons

The O-, N-, Mo-, Ru-, Os-, Cr-, Ti-, Ni-, Fe-, Nd-, Ca-, Zn-, Sr-, and Mg-isotopic compositions of enstatite chondrites are essentially identical to those of the Earth and Moon. These correspondences suggest enstatite chondrites formed at ≈1 AU as the only known chondrite groups that accreted in the vicinity of a major planet. Bulk Earth has a higher Mg/Si weight ratio (1.09) than enstatite chondrites (0.63–0.76) and aubrites (0.84). Earth could have accreted from a mixture of these materials along with forsterite (Mg/Si = 1.73) and niningerite [(Mg,Fe)S] from the lower mantles of aubritic parent asteroids whose crusts and upper mantles were stripped off by hit-and-run collisions. The highly reducing conditions in which enstatite chondrites formed resulted from the dehydration of the inner regions of the nebula caused by outward diffusion of water vapor; this lowered the H2O/H2 ratio of the gas. The minor fraction of oxidized material in enstatite chondrites formed earlier—when the H2O/H2 ratio was briefly enhanced by inward-migrating ice particles. Enstatite chondrites are the most shocked chondrite groups, exhibiting a large variety of shock features—for example, deformed silicate lattices; petrofabrics; brecciation; shock veins; metal globules; coesite; impact-melt textures; impact-produced phases (keilite, sinoite, graphite and F-rich minerals); and fractionated bulk REE patterns. The Ar-Ar, Rb-Sr and I-Xe ages of enstatite chondrites indicate many of these rocks were shocked early in Solar System history, 4520–4563 Ma ago. This interval stretches back to the period of giant-planet migration, when the 1 AU region became dynamically excited.

¹Sierra R. Ramsey,¹Piper Irvin,¹Arya Udry,²Scott A. Eckley,^3,4Amanda Ostwald,⁵Richard A. Ketcham
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009220]
¹Department of Geoscience, University of Nevada, Las Vegas, NV, USA
²Amentum, NASA Johnson Space Center, Houston, TX, USA
³Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, NW, USA
⁴Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, USA
⁵Jackson School of Geosciences, University of Texas, Austin, TX, USA
Published by arrangement with John Wiley & Sons

Nakhlites, clinopyroxene-rich rocks, are the largest single-origin suite of samples from Mars. Despite extensive study to discern their petrogenetic histories, nakhlite emplacement mechanisms and environments are not well-constrained, and it is unknown whether they represent intrusive or extrusive igneous rocks, or a combination. Here, we use X-ray computed microtomography (XCT) and three-dimensional (3D) quantitative textural analyses (e.g., 2D–3D modal abundances, crystal size distributions [CSDs], and petrofabrics) to place additional constraints on nakhlite formation and emplacement. Modal abundances between and within the nakhlites are variable on both a 2D and 3D basis, highlighting the significance of XCT and 3D analyses when studying these samples. All nakhlites in our study have similar crystallization conditions and histories based on 3D CSDs. Cumulus phases (=olivine and pyroxene) crystallized from magma(s) with high nucleation densities, likely related to effective undercooling, and subsequently underwent a period of magma storage. The CSD profiles record evidence for magma recharge events. Pyroxene long-axis orientations in the nakhlites studied here exhibit a magmatic foliation, which likely developed during crystal settling and accumulation in low-to-no flow settings, such as magma chambers, shallow intrusions (e.g., sills and dikes), lava lake or pond infills, or thick lava flows. We also show that the pyroxenitic layer of Theo’s Flow (Canada) may not be an appropriate terrestrial analog for the nakhlites due to differences in emplacement mechanisms and conditions. Our findings suggest that lava flows may be less prevalent in the martian meteorite collection, while intrusive bodies and rocks may be more common than initially thought.

¹P. Struzynska,¹S. Alwmark,¹C. Alwmark,²M. H. Poelchau,³P. Lambert
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70078]
¹Department of Geology, Lund University, Lund, Sweden
²Department of Geology, University of Freiburg, Freiburg, Germany
³CIRIR, Center for International Research and Restitution on Impacts and on Rochechouart, Rochechouart, France
Published by arrangement with John Wiley & Sons

Rochechouart, south-west France, is a complex impact structure. Here, we present the first report of shock barometry of quartz from what are likely parautochthonous basement units at depth, based on samples from the 2017 C.I.R.I.R drilling campaign. The crystallographic orientations of 725 sets of PDFs in 512 quartz grains in samples from four drill cores were measured. We find basal PDFs (Brazil twins) as shear indicators and rhombohedral PDFs recording moderate shock pressures of 10–15 GPa, with numbers of sets per grain ranging from 1.0 to 2.1. A staggering 59.5% of the measured parautochthonous PDF sets are basal PDFs. We find a decrease of shock-metamorphic overprint from 10–15 to 5–10 GPa at site SC16 (Montoume), ~4.5 km south of what is currently held as the apparent crater center. Based on the abundance of low-to-moderate shock pressures and a lack of more highly shocked parautochthonous units, we discuss two well-defined scenarios for this occurrence. Scenario 1 attributes Rochechouart parautochthonous basement target material to have been subjected to at most 15 GPa as per our results. In scenario 2, the drilling only sampled the flanks of the central uplift but not its more strongly shocked center. Our favored hypothesis is the latter, and thus we relate our lack of highly shocked parautochthonous units to a lack of samples from the immediate center of the structure. Finally, based on the extent of PDFs from our shock barometry study of quartz, we estimate the minimum extent for the diameter of the structure to be 24 km.

¹Tara S. Hayden,¹Gordon R. Osinski
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70074]
¹Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada
Published by arrangement with John Wiley & Sons

Apollo sample 67015 has been classified as a fragmental breccia comprised of highlands-type clasts and is proposed to be the most complex Apollo 16 sample. 67015 is dominated by impact melt rock clasts that display a variety of textures, which have been previously interpreted to be indicative of multiple impact events. Recent modeling has indicated that the Apollo 16 regolith may contain impact basin ejecta from Nectaris, Serenitatis, Imbrium, and Orientale. Here, the textural, mineralogical, and geochemical diversity of impact melt rock clasts in several thin sections of 67015 was assessed to evaluate the provenance of these impact melts and attempt to constrain the basin ejecta emplacement at the Apollo 16 site. The petrography and mineral chemistry of the melt rock clasts is highly diverse and may indicate a variety of sources, supporting previous evidence that the Apollo 16 regolith received ejecta from numerous large impact cratering events including Imbrium and Serenitatis. The diversity of clast types observed in 67015 and textural variability of thin sections prompts discussion into the most appropriate classification of this sample as well as the nomenclature used to describe lunar melt-bearing breccia samples.

¹Karl Wimmer,²Edwin Gnos,³Beda Hofmann,⁴Sandro Boschetti,⁴Jan Walbrecker,⁴Hansruedi Maurer
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70079]
¹Independent Researcher, Nördlingen, Germany
²Natural History Museum of Geneva and Earth and Environmental Sciences, University of Geneva, Geneva, Switzerland
³Natural History Museum Bern, Bern, Switzerland
⁴Institute of Geophysics, ETH Zürich, Zürich, Switzerland
Published by arrangement with John Wiley & Sons

With a size of 51.2 × 7.2 km, the 10.9 ± 1.7 ka old Jiddat al Harasis 091 L5 chondrite strewn field is the largest known in Oman. It consists of more than 700 meteorites with a total mass of >4.5 tons from which the largest six stones of >100 kg to 1.5 tons make up two thirds of the total mass. Small stones are underrepresented, consistent with a fracturing behavior of a meteor with low shock level. Modeling yields that a bolide with 28 ± 12 tons (115 ± 15 cm radius) entered the atmosphere at a shallow angle of 22° ± 2° with a velocity of about 16 kms−1. For ~16 s, it produced a spectacular meteor along a luminous path of ~200 km length. Mass mixing within the rather straight and narrow strewn field indicates a sequence of multiple fragmentations from below 50 km down to 7 km altitude. This can be resolved adopting a wind profile from nowadays winter season, as the weather patterns with alternating Monsoon and Passat winds in the region are rather well known and repeatable since the last ice age. The largest masses with 1447 and 842 kg, respectively, produced impact breccia consisting of limestone and meteorite fragments. According to the model, the biggest mass hit the ground at a velocity of 175 ms−1 and released an impact energy of 22 MJ, corresponding to 5.3 kg TNT. This may have produced an impact crater of ~1 m diameter which, however, is not preserved. Breccia found below a much smaller mass of 68 kg deserves an explanation beyond impact energy.

^1,2Tian Zhang, ^1,2,3Hong Tang, ^1,2,3Xiongyao Li, ^1,3Bing Mo, ¹Yuanyun Wen, ⁴Sheng Zhang, ^1,3Wen Yu, ^1,2Chuanjiao Zhou, ^1,2Haiyan Long, ^1,2,3Jianzhong Liu
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.11.047]
¹Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
²College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
³CAS Center for Excellence in Comparative Planetology, Hefei 230026, China
⁴College of Resources and Environment Engineering, Guizhou University, Guiyang 550025, China
Copyright Elsevier

The degassing of solar wind-related volatiles is thought to contribute to volatile cycling on the Moon. However, it remains uncertain which lunar minerals preferentially release them. Here, we report an unusual foamy texture found only on the surface of ilmenite crystals within a Chang’e-6 (CE-6) basalt clast. The distribution and chemical composition of this texture indicates that it results from in-situ melting of the ilmenite surface rather than from an impact-induced splash melt. Considering the evidence—including the long exposure time, presence of deep-seated planar defects, open vesicles, large spherical np-Fe⁰ particles, and a rutile-like mineral—the foamy texture is interpreted to result from the intense release of abundant solar wind-related volatiles (e.g., H/H2, He, and OH/H2O) by an impact-induced conductive heating event. Restriction of the foamy texture to the surface of ilmenite within the CE-6 basalt clast indicates that solar wind composition, especially for H-related volatiles, are released more intensely from ilmenite than from silicate minerals such as pyroxene and plagioclase. Our findings suggest that solar wind-related volatiles released from high-Ti mature regolith likely made a greater contribution to the lunar exosphere and the lunar surface volatiles, including polar deposits, relative to those from low-Ti immature regions. This has important implications for understanding volatile cycles and future in-situ resource utilization on the Moon.