^1,2Neha Panwar, ¹Neeraj Srivastava, ³Ankita Yadav, ¹Megha Bhatt, ⁴Christian Wöhler, ¹Anil Bhardwaj
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2025.116641]
¹Planetary Remote Sensing Section, Planetary Sciences Division, Physical Research Laboratory, Ahmedabad 380009, India
²Discipline of Earth Sciences, Indian Institute of Technology, Gandhinagar, India
³Banasthali Vidyapith, Rajasthan, India
⁴Image Analysis Group, TU Dortmund University, Dortmund, Germany
Copyright Elsevier

The Crisium Basin (17.0°N, 59.1°E) is a Nectarian multi-ring basin hosting extensive volcanism inside the basin center and along its four rings. The Crisium Basin is an essential proxy for understanding basin-related magmatic activity on the Moon. A detailed stratigraphy and chronology have been established for the Mare Crisium in several earlier studies. However, there has been no comprehensive study regarding the composition and emplacement timescales of the basalts along the rings of the Crisium Basin. The basalts along the rings of the Crisium Basin have been emplaced within Mare Undarum, Mare Spumans, Mare Anguis, Cleomedes Crater, and Lacus Bonitatis. Our recent study identified Marginis West as an episode of volcanism along the outermost ring of the Crisium Basin. This study, for the first time, examines the compositional diversity and ages of the basalts emplaced along the rings of the Crisium Basin to better understand its geological evolution. We report the youngest volcanic unit emplaced inside the Crisium Basin at ~2.0 Ga inside Mare Anguis. Based on the spectral signatures, we report that the contemporaneously formed mare units within the Crisium Basin are compositionally different, displaying a westward increase in Ca, and large pre-existing crustal structures would have deeply influenced the volcanism within the basin in the region.

^1,2,3Steven J. Jaret,⁴William R. Hyde,⁵Leah Shteynman
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14354]
¹Department Physical Sciences, Kingsborough College CUNY, Brooklyn, New York, USA
²Department Earth and Environmental Sciences, CUNY Graduate Center, New York, New York, USA
³Department Earth and Planetary Sciences, American Museum of Natural History, New York, New York, USA
⁴Department of Geology, Lund University, Lund, Sweden
⁵School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
Published by arrangement with John Wiley & Sons

New mapping and laboratory studies of the impactites at the Gardnos impact structure (Norway) show a variety of impact-deformed rocks. Our mapping and petrographic analyses have subdivided these breccias into three distinct categories: (a) melt-bearing sueivitic breccias, melt-bearing polymict breccias; (b) melt-free, polymict lithic impact breccias; and (c) monomict lithic impact breccias. This illustrates the dynamic nature of crater floor processes where mixing occurs in multiple ways. Feldspar grains exhibit evidence of intense shear, micro-faults, and alternate twin deformation in feldspar. We also observe the development of additional, amphibole-like planar elements (or cleavage) in biotite. Melt-bearing breccias contain carbon concentrations up to an order of magnitude higher than the target rocks. Unusual textures of carbon petrographically associated with shock and post-shock features in feldspars suggest significant postimpact hydrothermal mobilization of carbon within these rocks. Gardnos, therefore, represents an important terrestrial analog for understanding a suite of impact- and postimpact geologic processes.

¹Ryota Fukai, ²Yusuke Takeda, ^3,4Yuki Masuda, ^4,5Daiki Yamamoto, ⁶Yasuhiro Iba, ⁶Shintaro Sasaki, ⁶Shin Ikegami, ⁷Aya Kubota,⁸Reo Sato, ^1,8Tomohiro Usui
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2025.116648]
¹Astromaterial Science Research Group, Japan Aerospace Exploration Agency
²Scattering and Imaging Division, Japan Synchrotron Radiation Research Institute
³Department of Earth and Planetary Sciences, Institute of Science Tokyo
⁴Centre for Star and Planet Formation, Globe Institute, University of Copenhagen
⁵Department of Earth and Planetary Sciences, Kyushu University
⁶Department of Earth and Planetary Sciences, Hokkaido University
⁷Research Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology
⁸Department of Earth and Planetary Science, The University of Tokyo
Copyright Elsevier

The evolution associated with coagulation/fragmentation processes of dust to planetesimals in the protosolar disk is the critical phase of planet formation in the Solar System. The meteoritic components, such as calcium‑aluminum-rich inclusions (CAIs), will provide essential constraints on the coagulation/fragmentation process in the early stage of the disk. We applied the bright-field grinding tomography method to an Allende meteorite (CV3) slab to visualize the coarse-grained CAIs (CG-CAIs) in a colorized 3D model with high spatial resolution. We found four mm-scale CG-CAIs that experienced deformation and/or fragmentation processes within ~1.8 × 103 mm3 Allende slab. An angular-shaped CG-CAI’s surface showed the anisotropy of red-gray and white sides, which suggests that the fragmentation results in the loss of the primitive Wark-Lovering rim. We also found a vesicular-shaped CG-CAI, which indicates that the fracturing and complex formation process of this CG-CAI likely proceeded prior to the accretion of the Wark-Lovering rim. Our observations reveal that the fragmentation of Allende CAIs occurred during the parent body accretion stage and also in the protosolar disk.

¹Elias Wölfer, ¹Christoph Burkhardt, ²Francis Nimmo, ¹Thorsten Kleine
Earth and Planetary Science Letters 663, 119435 Open Access Link to Article [https://doi.org/10.1016/j.epsl.2025.119435]
¹Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
²Department of Earth and Planetary Sciences, University of California Santa Cruz, 1156 High St, Santa Cruz, CA 95064, USA
Copyright Elsevier

The bulk silicate Earth (BSE) is depleted in moderately volatile elements, indicating Earth formed from a mixture of volatile-rich and -poor materials. To better constrain the origin and nature of Earth’s volatile-rich building blocks, we determined the mass-dependent isotope compositions of Ge in carbonaceous (CC) and enstatite chondrites. We find that, similar to other moderately volatile elements, the Ge isotope variations among the chondrites reflect mixing between volatile-rich, isotopically heavy matrix and volatile-poor, isotopically light chondrules. The Ge isotope composition of the BSE is within the chondritic range and can be accounted for as a ∼2:1 mixture of CI and enstatite chondrite-derived Ge. This mixing ratio appears to be distinct from the ∼1:2 ratio inferred for Zn, reflecting the different geochemical behavior of Ge (siderophile) and Zn (lithophile), and suggesting the late-stage addition of volatile-rich CC materials to Earth. On dynamical grounds it has been argued that Earth accreted CC material through a few Moon-sized embryos, in which case the Ge isotope results imply that these objects were volatile-rich, presumably because they were either undifferentiated or accreted volatile-rich objects themselves before being accreted by Earth.

¹Lisa Maria Eckart, ¹Henner Busemann, ¹Daniela Krietsch, ¹Cornelia Mertens, ¹Colin Maden, ²¹Conel M. O’D. Alexander, ^3,4Kevin Righter
Geochimica et Cosmocimica Acta )(in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.04.021]
¹Institute of Geochemistry and Petrology, ETH Zurich, Clausiusstrasse 25, 8092 Zurich, Switzerland
²Carnegie Institution for Science, 5251 Broad Branch Rd NW, Washington, DC 20015, United States
³NASA Johnson Space Center, 2101 E NASA Pkwy, Houston, TX 77058, United States
⁴Department of Earth and Environmental Sciences, University of Rochester, 227 Hutchison Hall, Rochester, NY 14627, United States
Copyright Elsevier

Carbonaceous chondrites of the Ornans type (COs) include some of the most primitive meteorites known to date, yet most of them show evidence of having experienced mild degrees of thermal alteration in their parent asteroid. Previous studies on aqueously altered CM, CR, and CY chondrites have shown that the noble gases trapped in various components with distinct susceptibility to alteration can be used to assess the extent of parent body processing. In this study, we investigated the noble gas compositions of 51 CO chondrites ranging from petrologic type 3.0 to 3.8, three suspected Mighei-type chondrites (CMs; MIL 090073, DOM 10121, DOM 10299) initially classified as COs, and DOM 10900 with intermediate properties between CMs and COs. The COs show a noble gas mixture typical for carbonaceous chondrites, deriving from primordial carriers such as presolar grains, phase Q, and the carrier of the Ar-rich/V component, which has been observed in anhydrous chondrites, and occasionally air. Additionally, the newly identified W component could be present, which is highly susceptible to water. Combining our results with CO noble gas data from the literature, we show that the 20Netr/132Xecorr ratios correlate best (decrease) with the degree of thermal alteration, likely related to the abundance of presolar diamonds, and may thus serve as tool to subclassify thermally altered chondrites. Based on its 20Netr/132Xecorr ratio, DOM 10847 (paired with DOM 08006) is the most primitive CO, followed by NWA 13464 and Y-74135. The 20Netr/132Xecorr subclassification tool, however, may not be applicable for intergroup comparisons as the stability of the responsible carriers are sensitive to the chemical environment of the parent body. The abundances of heavy noble gases in bulk CO samples are much higher compared to CO etch residues (remaining after demineralization of a bulk meteorite) from the literature, indicating that other carrier(s) than insoluble organic matter must contribute significantly to the heavy noble gas inventory, which is/are susceptible to thermal alteration. DaG 331 was subclassified in this work to be a CO3.1 using the method by Grossmann and Brearley (2005) and the trend line defined by Davidson et al. (2019).
The COs show a wide range in cosmic ray exposure (CRE) ages between 0.17 ± 0.05 Ma (Isna) and 78 Ma (maximum age determined for Dominion Range [DOM] 18286 with an uncertainty of < 10 %), although the majority of CRE ages are > 10 Ma. DOM 18286 has the highest CRE age reported to date for a carbonaceous chondrite. We did not find any age clusters hinting at a major impact event, nor a correlation between CRE ages and the petrologic types. Strikingly, none of the 63 COs analyzed for their noble gases (including literature) contains solar wind, indicating that this group stems from below the regolith surface layer. The COs and CMs show similar matrix-corrected primordial noble gas abundances, suggesting that they accreted their volatiles from a common reservoir.

¹Nathan Asset, ¹Marc Chaussidon, ²Christian Koeberl, ³Johan Villeneuve, ⁴François Robert
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Access [https://doi.org/10.1016/j.gca.2025.05.011]
¹Université Paris-Cité, Institut de Physique du Globe de Paris, CNRS, F-75005 Paris, France
²Department of Lithospheric Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
³Université de Lorraine, CNRS, CRPG, UMR 7358, F-54000 Nancy, France
⁴Institut Origine et Evolution, Muséum National d’Histoire Naturelle, Sorbonne Université, IMPMC-UMR 7590 CNRS, 75005Paris, France
Copyright Elsevier

During the world’s first nuclear explosion, in 1945, glassy melts called “trinitites”, mostly derived from the sands at the surface of the test site, formed and were deposited at or near the hypocenter. The processes of formation of this fallout remain unclear. Here, we show how the oxygen and silicon isotopic compositions of three trinitites allow to refine their formation scenario. The three samples are typical of trinitites, being composed of various crystalline phases (feldspars, quartz, and calcite) and of glassy phases divided into three chemical groups (CaMgFe, alkali, silica) that are mixed in various proportions in the three samples. The three samples show a large range of oxygen and silicon isotopic variations (−10.9 ± 0.6 ‰ <δ30Si < 4.2 ± 0.6 ‰, and 2.3 ± 0.4 < δ18O < 24.2 ± 0.5 ‰). At variance with the Hiroshima fallout deposits, no oxygen mass-independent isotopic fractionation was found in the three trinitites. The chemical and isotopic compositions of the chemical groups reveal that they result from different processes: the silica phases are molten fragments of the site material, while the CaMgFe and alkali phases are produced by the mixing of condensates and molten site material. Models show that the observed silicon isotopic variations resulted from Rayleigh distillation during condensation of the gaseous species injected into the cloud, while the variability in composition of the site materials also played an important role for controlling the oxygen isotopic compositions. From these observations, a general scenario, beginning with the vaporization of the site surface, producing a depression, is proposed. The vaporized material condensed and grew by agglomeration with other condensates and liquid materials. These agglomerates rained on the surface and quenched, forming the trinitites. This scenario is different from the formation of the Hiroshima glasses but shows some similarities to the tektites formation.

¹Elizabeth A. Heiny,¹Edward M. Stolper,¹John M. Eiler
Proceedings of the National Academy of Sciences of the United States of America (PNAS) 122, e2418198122 Link to Article [https://doi.org/10.1073/pnas.2418198122]
¹Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125

The isotope anomalies of noncarbonaceous (NC) and carbonaceous (CC) extraterrestrial materials provide a framework for tracing the distribution and accretion of matter in the early solar system. Here, we extend this framework to sulfur (S)—one of six “life-essential” volatile elements [TC ~ 664 K]—via the mass-independent S-isotope compositions of differentiated meteorites. We observe that on average, NC and CC iron meteorites are characterized by distinct Δ33S (Δ33SNC = 0.013 ± 0.003‰; Δ33SCC = −0.021 ± 0.009‰; 2 SE). The average Δ36S of NC and CC irons are less well resolved (Δ36SNC = −0.006 ± 0.039‰; Δ36SCC = −0.101 ± 0.114‰; 2 SE), but the Δ36S values of the CC irons are concentrated in the lower half of the range of those observed for iron meteorites. A lack of CC achondrite S-isotope analyses prevents direct comparison of the Δ33S and Δ36S of NC and CC achondrites, but the average Δ33S and Δ36S of NC achondrites (Δ33S = 0.02 ± 0.008; Δ36S = −0.019 ± 0.064‰; 2 SE) overlap with those of the NC irons. The average Δ33S values of NC achondrite groups also correlate with nucleosynthetic anomalies of other elements (e.g., Cr) previously used to define isotopic heterogeneity within the NC reservoir. The position of the Earth in Δ33S-Δ36S composition space implies that ~24% of terrestrial S derives from CC materials, while the majority (~76%) was delivered by NC materials.

¹Nathan Asset, ¹Marc Chaussidon, ²Guillaume Lombardi, ³Johan Villeneuve, ⁴Romain Tartèse, ⁵Smail Mostefaoui, ⁵François Robert
Proceedings of the National Academy of Sciences of the United States of America (PNAS) 122, e2426711122 Link to Article [https://doi.org/10.1073/pnas.2426711122]
¹Universite Paris-Cite, Institut de Physique du Globe de Paris, CNRS, Paris F-75005, France
²Laboratoire des Sciences des Procédés et des Matériaux (LSPM—CNRS), Université Sorbonne Paris Nord, Villetaneuse F-93430, France
³Centre de Recherches Pétrographiques et Géochimiques, CNRS, Université de Lorraine, UMR 7358, Vandœuvre-lès-Nancy 54501, France
⁴Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
⁵Institut Origine et Evolution, Muséum National d’Histoire Naturelle, Sorbonne Université, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie – UMR 7590 CNRS, Paris 75005, France

Contrary to all terrestrial rocks, planets and meteorites exhibit oxygen isotope variations decorrelated with the mass difference of their atomic nuclei. It has been proposed that, in the protosolar nebula (PSN), these variations could result from mass independent isotopic fractionation (MIF) either during specific chemical reactions similar to those responsible for the formation of ozone in the Earth’s atmosphere or during ultraviolet (UV)-photolysis of carbon monoxide (CO) gas in the PSN. However, these potential chemical MIF reactions (Chem-MIFs) are not identified in conditions close to the PSN, and there is no experimental demonstration that large MIF signature can be transferred to solids forming in the PSN. Here, we show that MIFs, up to 60‰ depletion in 16O, are produced by high-temperature reactions in a plasma during the condensation of carbonaceous solids from a gas containing two of the most abundant PSN molecular species (H2O and CH4). This effect is attributed to the formation in the plasma of the activated complex H2O2* followed by its stabilization by reactions with CHx• radicals. Although it is premature to assert that this reaction represents the main process resulting in MIF of oxygen isotopes in the solar system, our result demonstrates the potential importance of a Chem-MIF effect in a PSN where plasma zones develop.

^1,2J.S. Gorce, ^2,3E.A. Heiny, ⁴J. Filiberto, ²C. Goodrich
Earth and Planetary Science Letters 662, 119371 Link to Article [https://doi.org/10.1016/j.epsl.2025.119371]
¹Amentum at NASA Johnson Space Center, Houston, TX, 77058, United States
²Lunar and Planetary Institute, USRA, Houston, TX 77058, United States
³Case Western Reserve University, Cleveland, OH 44106, United States
⁴Astromaterials Research and Exploration Sciences, NASA Johnson Space Center, Houston, TX 77058
Copyright Elsevier

There is a growing body of evidence that the range of planetary parent bodies sizes is greater than previously understood as new pressure and temperature (P-T) estimates of amphibolite and eclogite mineral assemblages found in chondrites are determined and subsequently used to estimate parent body sizes. Here we use thermodynamic modelling techniques to estimate that clasts containing eclogite-like minerals found in NWA 801 equilibrated at 13-15 kbars and 720°C under dry metamorphic conditions, and hydrous phases form after peak metamorphism during aqueous alteration at P∼4-6 kbars and T ∼ 200-400°C and a water/rock ratio of ∼0.006 (< 0.5 wt % H2O). Parent body size estimates are similar to previous work (2050-3700 km), but do not require that the eclogitic clasts be sampled from near the center of the parent body to achieve a peak metamorphic pressure of 13-15 kbars. The eclogitic clasts in NWA 801 are part of a growing body of evidence that imply that chondritic parent bodies could have been much larger than what has been suggested in the past (1000s vs 10s-100s km in diameter), and that the diversity of size in chondritic parent bodies is much greater than previously understood.

¹Magdalena H. Huyskens, ^2,3,4Yuri Amelin, ¹Qing-Zhu Yin, ⁵Tsuyoshi Iizuka
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.04.030]
¹Department of Earth and Planetary Sciences, University of California, Davis, Davis, CA 95616, USA
²Research School of Earth Sciences, Australian National University, Canberra, ACT 2601, Australia
³Korea Basic Science Institute, Ochang, Cheongwon, Cheongju, Chungbuk 28119, Republic of Korea
⁴State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry CAS, Guangzhou 510640, China
⁵Department of Earth and Planetary Science, The University of Tokyo, Japan
Copyright Elsevier

Ages of angrites, a diverse and rapidly growing group of differentiated meteorites, are important for understanding the history of their parent body, which is proposed to be an archetypal first-generation planetesimal. Angrites also commonly serve as a time reference in the early Solar System chronology. Pb-isotopic ages of angrites can be determined with high precision, and the isotopic composition of uranium thus becomes a major contributor to the age accuracy and its total uncertainty budget. Two main groups of angrites, the rapidly cooled (volcanic and/or impact-generated) and plutonic angrites, were previously found to contain uranium with different 238U/235U ratios. The variations in isotopic compositions between mineral carriers of uranium within individual angrites, which are directly relevant to calculation of accurate Pb-isotopic ages, have not been studied yet. In this study, we determined the 238U/235U for whole rocks, leachate and residue of whole rocks and mineral separates for two rapidly cooled angrites D’Orbigny and Sahara 99,555 and three plutonic angrites NWA 4801, NWA 4590 and Angra dos Reis. For the rapidly cooled angrites, all mineral separates as well as the whole rocks show consistent 238U/235U. Whole rock 238U/235U ratios for the plutonic angrites are distinctly lower than the ratios in the rapidly cooled angrites. In Angra dos Reis and NWA 4590, merrillite has higher 238U/235U than pyroxene, and both minerals have higher 238U/235U ratios than the respective whole rock, suggesting the presence of an unidentified mineral host of uranium with lower 238U/235U. These differences in U isotope composition could be possibly attributed to a combination of mass dependent and mass-independent isotope fractionation driven by the differences of oxidation state, and coordination in the crystals. We recalculated the existing Pb-isotopic dates when possible with the measured 238U/235U for the minerals that were used for the Pb-isotopic dating. The differences in U isotopic composition between cogenetic minerals point to the importance of 238U/235U determination in specific minerals that are used for Pb-isotopic dating for plutonic achondrites, rather than U isotopic data for bulk meteorites