¹M.E.I.Riebe et al.(>10)
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.01.034]
¹Institute of Geochemistry and Petrology, ETH Zürich, CH-8092 Zürich, Switzerland
Copyright Elsevier

Most ureilites are melt residues from the partially melted Ureilite Parent Body. The Ureilite Parent Body was catastrophically disrupted at ∼ 5 Ma after CAI while it was still hot and the ureilites provide a unique window into early solar system magmatic processing. One ureilitic trachyandesite, one cumulate, and 16 melt residue ureilites, all from the Almahata Sitta meteorite strewn field, were analyzed for their noble gas compositions and, when such data was unavailable, for oxygen isotopes and petrology. Additionally, ureilite noble gas data from the literature was compiled together with petrology and oxygen isotope data of the same samples, this data is available in the supplementary materials. The compositions of noble gases and oxygen, as well as petrological characteristics, are similar to previously analyzed ureilites. This includes variable 36Artr/132Xe ratios of ∼ 20–––1000 correlated with variable 84Kr/132Xe ratios of ∼ 0.15–––2.5 and Xe isotopic compositions similar to the Q gases but with somewhat lower 134,136Xe/132Xe ratios. The well-established correlation between Mg-Fe olivine core composition and Δ’17O, interpreted as material mixing, is corroborated. There is no correlation between noble gas compositions and petrology or Δ’17O. Therefore, it is unlikely that the variable noble gas elemental ratios are due to mixing of noble gases from different sources, as previously suggested. We suggest that compositional variability was established during implantation of noble gases into disordered carbon prior to accretion and possibly during later processing. We discuss that partial graphitization resulted in noble gas loss, with noble gases remaining in un-graphitized organics, which were converted to diamond during the catastrophic disruption. Noble gases released during graphitization may have entered the melt. Isotopic compositions of trapped noble gases in the cumulate and trachyandesitic rocks, which crystallized from the melt are similar to those in the melt residue ureilites. The elemental noble gas composition of the cumulate shows evidence of a degassing stage and that the concentrations of noble gases in the ureilites were higher before melting. The noble gases in the trachyandesite contains radiogenic noble gases from decay of K, I, Th, and U, which were not enriched in the cumulate, showing that the trachyandesite crystallized from a more evolved melt. The cosmic-ray exposure ages of 15–––22 Ma, with mostly overlapping uncertainties, are similar to those previously determined for ureilites from the Almahata Sitta strewn field and display a limited spread in contrast to ages previously detected in Almahata Sitta chondrites.

¹Alexander N. Krot, ¹Kazuhide Nagashima, ²Tasha L. Dunn, ³Chi Ma, ⁴Michail I. Petaev
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.01.027]
¹Hawai‘i Institute of Geophysics & Planetology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
²Department of Geology, Colby College, Waterville, ME 04901, USA
³Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
⁴Department of Earth & Planetary Sciences, Harvard University, Cambridge MA 02138, USA
Copyright Elsevier

We report on oxygen and aluminum-magnesium isotope systematics of Compact Type A (CTA), Type B (B), and Forsterite-bearing Type B (FoB) Ca,Al-rich inclusions (CAIs) from the Northwest Africa (NWA) 5343 (CK3.7) and NWA 4964 (CK3.8) chondrites that experienced metasomatic alteration in the presence of aqueous solution that resulted in replacement of primary melilite, AlTi-diopside, grossmanite, anorthite, and perovskite by secondary minerals. The primary minerals have excesses of radiogenic 26Mg (26Mg*) that correlate with 27Al/24Mg ratio; the only exception is melilite in the CTA CAI. The calculated internal Al-Mg isochrons in the CTA (excluding melilite), Type B, and FoB CAIs correspond to the initial 26Al/27Al ratios [(26Al/27Al)0] of (5.09 ± 0.58) × 10−5, (2.58 ± 3.2) × 10−5, and (5.05 ± 0.66) × 10−5, respectively. The gehlenitic melilite (Åk<1) in the CTA CAI has resolvable 26Mg* but very high 27Al/24Mg (up to ∼ 660) and does not belong to the internal isochron defined by hibonite, spinel, and grossmanite. The high 27Al/24Mg in melilite containing submicron inclusions of grossular is due to redistribution of Mg between these minerals during thermal metamorphism. Hibonite, spinel, forsterite, rhönite/louisfuchsite, and a grossmanite inclusion in spinel have 16O-rich compositions (Δ17O ∼  − 23 ± 2 ‰), whereas melilite, anorthite, and perovskite are 16O-poor (Δ17O ∼  − 3 ± 2 ‰). Grossmanite and AlTi-diopside are 16O-depleted to various degrees: Δ17O ranges from ∼  − 24 to ∼  − 3 ‰; the degree of 16O-depletion correlates with titanium content in pyroxene. On a three-isotope oxygen diagram secondary grossular, FeAl-diopside, FeMg-olivine, and plagioclase plot along mass-dependent fractionation line with Δ17O of ∼  − 3.7 ± 1.9 ‰ that corresponds to Δ 17O of metasomatic fluid in the host meteorites. This value is indistinguishable from Δ 17O of metasomatic fluid that resulted in alteration of Allende (CV > 3.6) CAIs.
Coarse-grained igneous CAIs in CKs and CVs have similar size distribution, textures and primary mineralogy, formed in a gas of approximately solar O-isotope composition (Δ 17O ∼  − 24 ± 2 ‰) and had the canonical (26Al/27Al)0, suggesting they belong to the same generation of refractory inclusions, further supporting genetic relationship between CVs and CKs. Oxygen-isotope heterogeneity in CV > 3.6 and CK3.7 − 3.8 CAIs resulted from postcrystallization O-isotope exchange with 16O-depleted metasomatic fluid (Δ 17O ∼  − 3.7 ± 1.9 ‰) on their parent asteroid(s). This exchange preferentially affected melilite, anorthite, perovskite, and AlTi-pyroxenes, whereas hibonite, spinel, rhönite/louisfuchsite, and forsterite retained their original 16O-rich compositions established during igneous crystallization in a gas of approximately solar composition. Metasomatic alteration and thermal metamorphism of CAIs from CK3.7 − 3.8 and CV > 3.6 chondrites disturbed their Al-Mg isotope systematics to various degrees.

¹A.Galiano et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14315]
¹INAF-IAPS Istituto di Astrofisica e Planetologia Spaziali, Rome, Italy
Published by arrangement with John Wiley & Sons

The spectral analysis of CM meteorites can help to constrain the mineralogical composition of their parent body, the C-type asteroids. The CM2 NWA 12184 was spectrally examined employing seven complementary techniques at different spatial resolutions, including VIS-to-MIR reflectance and Raman spectroscopy. Furthermore, the effects of space weathering on asteroids can be investigated by performing laboratory simulations on meteorites samples; thus, the meteorite was processed with He+ ions at 200 keV (maximum fluence of 1.0 × 1017 ions cm−2) to simulate the solar wind irradiation on C-type asteroids. We discriminated the mineralogical composition of the NWA 12184 at the millimeter scale and at the micrometer scale, investigating both matrix and chondrules. The ion experiment produced spectral darkening, reddening, shifting of the hydration band, and weakening of the absorption band ascribed to olivine in the VIS-NIR range, as well as the reduction in the olivine’s peak in MIR range, clue of the sample’s amorphization. The study identified the native mineralogy of the meteorite, the products of terrestrial weathering, and the aqueous and thermal alteration experienced by the parent body of the sample.

¹Kakeru Kukihara,¹Masaaki Miyahara,²Akira Yamaguchi,³Yoshio Takahashi,^4,5Yasuo Takeichi,⁶Naotaka Tomioka,⁷Eiji Ohtani
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14316]
¹Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, Japan
²National Institute of Polar Research, Tokyo, Japan
³Department of Earth and Planetary, Graduate School of Science, The University of Tokyo, Tokyo, Japan
⁴Institute of Materials Structure Science, High-Energy Accelerator Research Organization (KEK), Tsukuba, Japan
⁵School of Engineering, Osaka University, Osaka, Japan
⁶Kochi Institute for Core Sample Research, X-star, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Nankoku, Japan
⁷Department of Earth Sciences, Graduate School of Science, Tohoku University, Sendai, Japan
Published by arrangement with John Wiley & Sons

The petrologic and mineralogical characteristics and alteration processes of the nakhlites NWA 6148 and NWA 10153 were studied. Both consist of augite, olivine, and mesostasis. Based on the characteristics of each volume fraction of the components and the chemical composition of olivine and pyroxene, NWA 6148 correspond to lava units crystallized at 1346–1391 Ma in the nakhlite body. The position of NWA 10153 in the nakhlite body is unclear. Iron oxides/hydroxides, barite, and calcite fill the fractures of NWA 6148, which are terrestrial weathering products. In NWA 10153, olivine grains are replaced by goethite, magnetite, saponite, amorphous silica, jarosite, and siderite. Although it is uncertain whether all of the alteration minerals were formed on the surface of Mars or on the surface of Earth, NWA 10153 records two different alteration environments: reducing, neutral to alkaline, and oxidizing and acidic. As in NWA 6148 and NWA 10153, the assemblage of alteration mineral species in other nakhlites is also heterogeneous even within the same lava unit. The nakhlite body was altered by the oxidizing acidic fluid after a CO32−-bearing reducing neutral to alkaline fluid. The drastic change of alteration environments may have been caused by an impact event.

^1,2,3Jiaxin Xi,^1,3Yiping Yang,^1,2,3Hongping He,^1,3Haiyang Xian; Shan Li,^1,3Xiaoju Lin,^1,2,3Jianxi Zhu,⁴H. Henry Teng
American Mineralogist 110, 171-180 Link to Article [https://doi.org/10.2138/am-2023-9214]
¹CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
²University of Chinese Academy of Sciences, Beijing, China
³CAS Center for Excellence in Deep Earth Science, Guangzhou, China
⁴Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China

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¹Arkadeep Roy,¹Ananya Mallik,²Kerri Donaldson Hanna,²Tyler J. Goepfert,²Richard L. Hervig
American Mineralogist 110, 154-170 Link to Article [https://doi.org/10.2138/am-2023-9122-a]
¹Department of Geosciences, University of Arizona, 1040 E 4th Street, Tucson, Arizona 85721, U.S.A
²Department of Physics, University of Central Florida, 4111 Libra Drive, Orlando, Florida 32816, U.S.A.
³School of Earth & Space Exploration, Arizona State University, 550 E Tyler Mall, Tempe, Arizona 85287-1404, U.S.A.

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¹Yong Wu et al. (>10)
Icarus (in Press) Link to Artile [https://doi.org/10.1016/j.icarus.2025.116459]
¹National Key Laboratory of Uranium Resources Exploration-Mining and Nuclear Remote Sensing, 100029 Beijing, China
Copyright ELsevier

Chang’E-5 samples provide unique insights into the composition of the lunar interior ~2 billion years ago, but geochemical models of their formation show a significant degree of discrepancy. Trace element abundance measurements in olivine grains in Chang’E-5 sub-sample CE5C0600YJFM002GP provide additional constraints on the basalt source. Geochemical modeling indicates that low-degree (4 %) batch melting of an olivine-pyroxenite lunar magma ocean cumulate, incorporating high levels of trapped lunar magma ocean liquid and plagioclase, can reproduce the rare earth element, Sr, Rb, Sc, Co and Ni abundances in our and previously reported Chang’E-5 samples, as well as observed Rb-Sr and Sm-Nd isotope systematics. Overall, these results strengthen the direct geochemical links between lunar magma ocean evolution and basaltic volcanism occurring ~2.5 billion years later. Additionally, Chang’E-5 high-Fo olivine is enriched in the volatile element Ge (1.38–3.94 μg/g) by ~2 orders of magnitude compared to model results (< 0.02 μg/g). As Ge is a mildly compatible element with bulk Ge partition coefficients close to 1, a Ge-depleted initial LMO proposed by previous research cannot yield a high-Ge mantle source for Chang’E-5 basalt, even when invoking assimilation of high-Ge LMO cumulates. The overabundance of Ge requires either a high-Ge, volatile rich initial bulk Moon with chondritic composition or a late Ge chloride vapor-phase metasomatism.

¹Christian Potiszil, ¹Tsutomu Ota, ¹Masahiro Yamanaka, ¹Katsura Kobayashi, ¹Tanaka, ¹Nakamura
Earth and Planetary Science Letters 653, 119205 Open Access Link to Article [https://doi.org/10.1016/j.epsl.2025.119205]
¹Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University, Yamada 827, Misasa, Tottori 682-0193, Japan
Copyright Elsevier

Carbonaceous chondrites (CC) and asteroid return samples contain amino acids (AA), which are essential for an origin of life on the early Earth and can provide important information concerning planetesimal alteration processes. While many studies have investigated AA from CC, separate studies have often found differing abundances for the same meteorite. Accordingly, analytical bias, differing terrestrial contamination levels and intrinsic sample heterogeneity have been proposed as potential reasons. However, current analytical techniques allow for the analysis of several mg-sized samples and can thus enable an investigation of AA heterogeneity within single meteorite specimens. Here, such an analytical technique is applied to characterise the AA in triplicate aliquots of three CCs. The results indicate that CCs are heterogenous in terms of their AA at the mm-scale. Furthermore, the results help to further constrain the effects of planetesimal alteration on organic matter and the requirements of future sample return missions that aim to obtain organic-bearing extraterrestrial materials.

¹C. J. Floyd,¹L. E. Jenkins,¹P.-E. Martin,^1,2,3L. Daly,¹M. R. Lee
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14303]
¹School of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK
²Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales, Australia
³Department of Materials, University of Oxford, Oxford, UK
Published by arrangement with John Wiley & Sons

CM chondrites have been subjected to numerous alteration processes including brecciation and ductile deformation. Here, we present the results of 2D and 3D petrofabric analysis across a suite of meteorites: Aguas Zarcas, Cold Bokkeveld, Lewis Cliff (LEW) 85311, Murchison, and Winchcombe. We find that chondrule-defined petrofabrics are commonplace, but not ubiquitous. Where petrofabrics are present, alignment is typically observed in the chondrule long axes defining foliation fabrics. Alongside previous authors we interpolate the shock pressures to generate such fabrics between 27.8 and 41.8 GPa. Impacts capable of generating these shock pressures should ordinarily produce shock microstructures in olivine something not observed in the CMs. Whilst high calculated pre-compaction porosities may have had a role in attenuating energy transfer during collisions, we suggest the assumption of chondrule sphericity used in these calculations is misplaced and that a non-spherical pre-deformation chondrule shape is likely responsible for the dichotomy. We also reveal that the relative timings of aqueous alteration, brecciation, and deformation vary between CMs. Within Aguas Zarcas, we find multiple lithic clasts interpreted as having experienced different degrees of aqueous alteration, with opposing fabrics that formed after water/rock interaction but prior to brecciation. Meanwhile, within Cold Bokkeveld, we find a consistent fabric between clasts suggesting the fabric was imposed after both aqueous alteration and brecciation.

^1,2C.S. Harrison et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14312]
¹Planetary Materials Group, Natural History Museum, London, UK
²Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
Published by arrangement with John Wiley & Sons

JAXA’s Hayabusa2 sample return mission visited the volatile-rich carbonaceous (C-type) asteroid (162173) Ryugu with the aim of ground-truthing remote observations, returning a pristine sample from a C-type asteroid, and strengthening links between asteroids and the meteorite collection. Here, we have conducted a systematic study of coarse (>10 μm) sulfide grains in Ryugu particles C0025-01 and C0103-02, the CI chondrites Orgueil and Ivuna, and the CY chondrites Y-86029 (Stage III, heated to 500–750°C) and Y-86720 (Stage IV, >750°C), using scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Sulfides are sensitive tracers of secondary alteration conditions, and we find that Ryugu and the CI chondrites share a distinct sulfide assemblage that includes the iron sulfides pyrrhotite and pentlandite, and the copper sulfide cubanite, that equilibrated during periods of low temperature (~25°C) aqueous alteration. Sulfides in the CY chondrites are compositionally distinct from Ryugu and the CI chondrites as a result of post-hydration heating. However, the occurrence of Cu-rich sulfides in Ryugu, the CIs, and the CYs suggests a genetic relationship between these samples.