^1,2Seann J. McKibbin,³Lutz Hecht,¹Christina Makarona,⁴Matthew Huber,³Hermann Terryn, ¹Philippe Claeys
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14147]
¹Analytical-, Environmental-, and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
²Geowissenschaftliches Zentrum, Abteilung Isotopengeologie, Georg-August-Universität Göttingen, Göttingen, Germany
³Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
⁴Department of Earth Science, University of the Western Cape, Bellville, South Africa
⁵Research Group of Electrochemical and Surface Engineering, Vrije Universiteit Brussel, Brussels, Belgium
Published by arrangement with John Wiley & Sons

The occurrence of forsteritic olivine in EH enstatite chondrites is indicative of bulk disequilibrium. In MgO-rich magmatic systems, forsterite can either crystallize as a liquidus phase or be produced during peritectic melting of enstatite. Because diffusion of divalent cations through forsterite is relatively rapid, it records peak melting (i.e., chondrule-forming events) and is also sensitive to subsequent metamorphism in the EH chondrite parent body. Here, we report the major and minor element geochemistry of olivine in EH chondrites across petrologic types 3 and 4. In all cases, olivine meets the technical definition of forsterite (>90 mole% Mg2SiO4). For unequilibrated EH chondrites, minor elements identify CaO-Al2O3-TiO2-rich (refractory forsterite), MnO-rich (“LIME” forsterite), and FeO-bearing (forsteritic olivine) endmember components, the latter with Cr2O3-rich and Cr2O3-poor varieties. At higher petrologic type, minor element concentrations become restricted and compositions approach pure forsterite, while grain sizes reduce strongly with peak metamorphic temperatures. These changes reflect diffusive equilibration with enstatitic groundmass and dissolution reaction with free silica. The global geochemical distribution of forsteritic olivine in EH chondrites is, perhaps unexpectedly, more similar to those in low-FeO type I chondrules and associated objects in carbonaceous chondrites (CCs), rather than equivalent objects in ordinary (H, L, LL), low-FeO (or HH), or Kakangari (K) chondrites. Among achondrites, there is similarity between pure forsterite in aubrites and EH4 chondrites arising due to subsolidus equilibration in both settings, while Cr2O3-poor forsteritic olivine in EH3 and CCs is similar to magnesian xenocrystic olivine in angrites. This might reflect CaO-rich and SiO2-poor magmatic sources across multiple early solar system reservoirs.

^1,2Robert W. Nicklas,³Kathryn G. Gardner-Vandy,¹James M. D. Day
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14142]
¹Scripps Institution of Oceanography, UniRobert W. Nicklas, Department of Earth and Environmental Sciences,
²Boston College, Chestnut Hill, MA 02467, USA.versity of California San Diego, La Jolla, California, USA
³Aviation and Space, Oklahoma State University, Stillwater, Oklahoma, USA
Published by arrangement with John Wiley & Sons

Highly siderophile elements (HSE) strongly partition into metal phases over silicate minerals and so offer important constraints on nebular and core formation processes acting on early planetesimals. Abundances of the HSE are also an important tool for constraining relationships between metal-rich meteorites. The first bulk rock and in situ HSE abundance and 187Re-187Os data are reported for the ungrouped metal-rich achondrite Tafassasset to examine models of its petrogenesis and origin. Bulk rock and metal grain HSE abundances are elevated at ~2 and ~15 times CI chondrite abundances, respectively, and are largely unfractionated from one another. Metal within Tafassasset is therefore likely to have quenched shortly after partial melting without significant fractional crystallization. Metal grain HSE abundances can be used to calculate a metal fraction of 14 ± 4 wt%, overlapping with the parent bodies of CC iron meteorites, which have also been related to Tafassasset using nucleosynthetic isotope anomalies. Despite such similarities, HSE systematics of bulk rock Tafassasset are not equivalent to any known chondrites, and metal grains do not overlap with iron meteorites or chondrite metal grains, precluding a direct genetic relationship.

¹Hunter Vannier,¹Briony Horgan,²Julie D. Stopar,^3,4,5Marie Henderson
Journal of Geophysical Researhc (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE008108]
¹Purdue University, West Lafayette, IN, USA
²Lunar and Planetary Institute, USRA, Houston, TX, USA
³Center for Space Sciences and Technology, University of Maryland, Baltimore, MD, USA
⁴Solar System Exploration Division, NASA/GSFC, Greenbelt, MD, USA
⁵Center for Research and Exploration in Space Science and Technology, NASA/GSFC, Greenbelt, MD, USA
Published by arrangement with John Wiley & Sons

Irregular mare patches (IMPs) are enigmatic volcanic features on the Moon’s surface, whose lack of cratering and crisp appearance imply they formed <100 Ma ago, ∼1 Ga after the expected turnoff of lunar volcanism. Multiple contrasting formation hypotheses have been put forth to explain their young appearance, including recent emplacement via eruptions of juvenile volcanic material or outgassing, versus ancient volcanic deposits that were emplaced billions of years ago but only appeared young due to highly porous material. If IMPs formed recently, this would require a reinterpretation of lunar thermal evolution. To help constrain formation hypotheses, we provide a comprehensive mineralogical analysis of IMPs using visible to near infrared hyperspectral data from the Moon Mineralogy Mapper. IMPs appear spectrally dominated by high-calcium pyroxene and are spectrally similar to their host mare and fresh craters. IMPs do not show clear indications of significant glass, implying that pyroclastic eruption was not significant in IMP formation. Based on spectral comparisons to terrestrial magma foam, we find that this also contradicts the glassiness expected for a magma foam exposed at the surface. Thus, we find it is unlikely that IMPs are composed of recently erupted material and may instead be the result of recent or ongoing surface modification of materials similar in composition and likely contemporaneously emplaced with the mare. We favor previous hypotheses that collapse processes or drainage into subsurface voids or porous materials may have been the major drivers of IMP surface rejuvenation, supported by their proximity to collapse features.

^1,2Eloy Peña-Asensio,^2,3Josep M. Trigo-Rodríguez,^4,5Jordi Sort,⁶Jordi Ibáñez-Insa,¹Albert Rimola
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14148]
¹Departament de Química, Universitat Autònoma de Barcelona, Barcelona, Spain
²Institut de Ciències de l’Espai (ICE, CSIC) Campus UAB, Cerdanyola del Vallès, Spain
³Institut d’Estudis Espacials de Catalunya (IEEC), Barcelona, Spain
⁴Departament de Física, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
⁵Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
⁶Geosciences Barcelona (GEO3BCN-CSIC), Barcelona, Spain
Published by arrangement with John Wiley & Sons

This study analyzes the mechanical and elemental properties of lunar meteorites DHOFAR 1084, JAH 838, NWA 11444, and HED meteorite NWA 6013. Utilizing microscale rock mechanics experiments, that is, nanoindentation testing, this research reveals significant heterogeneity in both mechanical and elemental attributes across the mineral samples. Olivines, pyroxene, feldspar, and spinel demonstrate similar compositional and mechanical characteristics. Conversely, other silicate and oxide minerals display variations in their mechanical properties. Terrestrial olivines subjected to nanoindentation tests exhibit increased hardness and a higher Young’s modulus than their lunar counterparts. A linear correlation is observed between the H/Er ratio and both plastic and elastic energies. Additionally, the alignment of mineral phases along a constant H/Er ratio suggests variations in local porosity. This study also highlights the need for further research focusing on porosity, phase insertions within the matrix, and structural orientations to refine our understanding of these mechanical characteristics. The findings have direct implications for in situ resource utilization strategies and future state-of-the-art impact models. This comprehensive characterization serves as a foundational resource for future research efforts in space science and mining.

^1,2Le Zhang,^1,2Ya-Nan Yang,^1,2Zhi-Ming Chen,^1,2Jintuan Wang,^1,2Cheng-Yuan Wang,^1,2Ze-Xian Cui,^1,2Yan-Qiang Zhang,^1,2Yi-Gang Xu
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2024.116002]
¹State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
²CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
Copyright Elsevier

Plagioclase is the most abundant mineral in lunar crustal rocks, and its elemental and Sr isotopic compositions vary among different lunar surface rock types, implying that plagioclase fragments in lunar regolith can be used to trace source-rock types. In this study, we measured major- and trace-elemental and Rbsingle bondSr isotopic compositions of plagioclase fragments from lunar soil returned by the Chang’e 5 (5CE) mission. Correlation between Sr and An contents allows the 5CE plagioclase fragments to be divided into three groups: normal-Sr (group A), high-Sr (group B), and low-Sr (group C). The similarity of elemental and Rbsingle bondSr isotopic compositions between plagioclase in groups A and B and plagioclase from 5CE basalt clasts indicates that plagioclase from groups A and B originated from the comminution of local 5CE basalt. Only two of the eighty-two analyzed plagioclases (~2.4%) are classified as group C and have Sr isotopes that are distinct from those of groups A and B plagioclases, indicating an exotic origin. One group C plagioclase has a high 87Sr/86Sr ratio (0.70242) and content of rare earth elements and might have been derived from the Sharp B or Aristarchus craters, which are enriched in the KREEP component. The other group C plagioclase has much lower 87Sr/86Sr (0.69908) and a moderately high content of An (92.3) indicating an Mg-suite source rock and possible derivation from the Pythagoras crater. This study highlights the applicability of using elemental and Sr isotopic compositions of plagioclase fragments to trace the origin of lunar regolith.

^1,2S. Benaroya,^1,3,4,5J. Gross,¹P. Burger,⁶M. Righter,⁶T.J. Lapen,⁷S. Eckley
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2024.02.004]
¹Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA
²Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton Alberta, Canada
³Department of Earth and Planetary Sciences, American Museum of Natural History, New York, NY, USA
⁴Lunar and Planetary Institute, Houston, TX, USA
⁵Astromaterials Research and Exploration Science Division, NASA JSC, Houston, TX, USA
⁶Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX, USA
⁷Jacobs – JETS, Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, TX, USA
Copyright Elsevier

Petrologic investigations of martian meteorite Northwest Africa (NWA) 13227 indicate it is an olivine-gabbroic shergottite, a relatively new shergottite group, which differs from previously described gabbroic shergottites due to relatively high quantities of olivine. NWA 13227 is comprised of phenocrystic, oscillatory-zoned pyroxene and olivine, set in a matrix of maskelynite, Fe-Cr-Ti oxides, phosphates, and sulfides. It displays gabbroic and poikilitic textures in 2D from back-scattered electron images, and in 3D from X-ray Computed Tomography (XCT) imaging, suggesting affinities to both poikilitic and gabbroic shergottites. Measured εHf and εNd values of bulk rock (-19.7 and −5.9, respectively) and its chondrite-normalized La/Yb ratio of 1.13 indicate the specimen is derived from a mantle reservoir relatively enriched in incompatible trace elements and is similar to that which produced most ‘enriched shergottites.’ Based on the Ti/Al ratio of pyroxene, phosphorous zoning in olivine, and minor components in phosphates and oxides, we infer that NWA 13227 began crystallizing under reducing conditions of QFM–2.6 and temperatures of ∼ 1100 °C, consistent with conditions in Mars’ lower crust/upper mantle. The sample finished crystallizing at or near the surface under redox conditions between QFM–0.5 to QFM–0.1 and temperatures of ∼ 850 °C. The volatile element compositions in apatite indicate that NWA 13227 experienced degassing during the last stages of crystallization. The timing of crystallization is estimated at 225 Ma ± 50 Ma using a Lu-Hf and Sm-Nd source versus age model.

¹Alexandra E. Doyle et al. (>10)
The Astrophysical Journal 950, 93 Open Access Link to Article [DOI 10.3847/1538-4357/acbd44]
¹Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095, USA

We present observations and analyses of eight white dwarf stars (WDs) that have accreted rocky material from their surrounding planetary systems. The spectra of these helium-atmosphere WDs contain detectable optical lines of all four major rock-forming elements (O, Mg, Si, and Fe). This work increases the sample of oxygen-bearing WDs with parent body composition analyses by roughly 33%. To first order, the parent bodies that have been accreted by the eight WDs are similar to those of chondritic meteorites in relative elemental abundances and oxidation states. Seventy-five percent of the WDs in this study have observed oxygen excesses implying volatiles in the parent bodies with abundances similar to those of chondritic meteorites. Three WDs have oxidation states that imply more reduced material than found in CI chondrites, indicating the possible detection of Mercury-like parent bodies, but are less constrained. These results contribute to the recurring conclusion that extrasolar rocky bodies closely resemble those in our solar system, and do not, as a whole, yield unusual or unique compositions.

^1,2Wang, Hongpeng,^1,3Xin, Yingjian,^1,3,4Fang, Peipei,^3,4Wang, Yian,^1,3Duan, Mingkang,⁵Wu, Wenming,⁶Yang, Ruidong,²Liu, Sicong ¹Zhang, Liang,^1,4Wan, Xiong
Chemosensors 11, 567 Open Access Link to Article [DOI 10.3390/chemosensors11110567]
¹Key Laboratory of Space Active Opto-Electronics Technology of the Chinese, Academy of Sciences, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
²College of Surveying and Geo-Informatics, Tongji University, Shanghai, 200092, China
³University of the Chinese Academy of Sciences, Beijing, 100049, China
⁴Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
⁵Geological Brigade 105, Bureau of Geology and Mineral Exploration and Development of Guizhou Province, Guiyang, 550018, China
⁶College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China

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

¹Liam D. Peterson,¹Megan E. Newcombe,²Conel M.O’D. Alexander,²Jianhua Wang ,^3,4Sune G. Nielsen
Geochimica et Cosmochimica acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.02.002]
¹Department of Geology, University of Maryland, College Park, MD 20740, United States
²Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, United States
³NIRVANA Labs, Woods Hole Oceanographic Institution, Woods Hole, MA 02540, United States
⁴Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02540, United States
Copyright Elsevier

The abundance of H in planetary building blocks is of fundamental importance for constraining the evolution of the terrestrial planets. It is commonly assumed that chondrites are the principal sources of Earth’s H; however, recent studies have suggested that primitive achondrites and achondrites may retain a small complement of H. There are few constraints on the H budgets of primitive achondrites, which represent the transition from unmelted to melted planetesimals, but prior work suggests that bulk parent body H contents are several orders of magnitude lower than typical chondritic values. Therefore, to provide further constraints on H retention during the transition from unmelted to melted planetesimals, we have measured the H contents of olivine, orthopyroxene, clinopyroxene, and plagioclase from a suite of acapulcoite-lodranite clan meteorites. Acapulcoite-lodranite clan meteorites represent the “prototypical” primitive achondrite parent body and have bulk major element compositions more akin to the Earth than previously studied primitive achondrites (e.g., the ureilites). We find that the H2O contents of olivine (∼5–12 µg/g H2O), orthopyroxene (∼3–10 µg/g H2O), and clinopyroxene (∼5–8 µg/g H2O) are broadly similar, while plagioclase (∼2.5–5 µg/g H2O) tends to be offset to lower values. Using a simple, single-stage batch-melting model, we calculate a preferred maximum acapulcoite-lodranite parent body H2O content of 38 µg/g, which is similar to other estimates for primitive achondritic and achondritic parent bodies. Furthermore, assuming chondrite-like precursor materials, our data are consistent with efficient loss of H prior to or during the onset of melting of early-formed planetesimals. This requires that Earth’s H-budget was dominated by building blocks that underwent minimal thermal processing.

¹K.Righter et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14146]
¹NASA Johnson Space Center, Houston, Texas, USA
Published by arrangement with John Wiley & Sons

The Dominion Range (DOM) and Miller Range (MIL) dense collection areas (DCAs) have yielded more than 20 and 200 CO3 chondrites (carbonaceous chondrites of the Ornans chemical group), respectively, over multiple field seasons. Several samples have exhibited primitive characteristics and have been the focus of interest. With so many CO3s recovered from this area, a natural question is if there are multiple pairing groups (where pairing refers to two or more meteorites that are part of a single fall) and if there is additional primitive material that would interest the meteorite community. This comprehensive study looks at all samples using several approaches: field and macroscopic observations; magnetic susceptibility; Cr in ferroan olivine; bulk elemental and isotopic analysis of H, C, N, and noble gas analyses to determine cosmic ray exposure (CRE) ages. Magnetic susceptibilities (measured as logχ) for all samples correlate with their type II (i.e., FeO-rich) olivine Cr contents, with the most primitive CO3s (3.00) have logχ values near 5, while the higher grade CO3s have logχ values as low as 4.17. Altogether, there appear to be two distinct CO3 pairing groups and five other unpaired CO3s recovered at the Dominion Range: (a) the main DOM 08004 pairing group (16 specimens with a CRE age of 10–16 Ma), (b) the DOM 08006 group (2 specimens incl. DOM 10847 with a CRE age of 25 Ma), (c) DOM 14359 with a CRE age of 6 Ma, (d) DOM 18070 with a CRE age of 8 Ma (these two samples have similar ages but distinct trapped 20Ne contents), (e) DOM 10900 with a CRE age of 5.5 Ma, (f) DOM 18286 (with a CRE age of ~59 Ma), and (g) DOM 19034 (with a CRE age of ~43 Ma). There are three distinct age groupings of 3.00–3.05 COs, highlighting the diverse pristine CO3 materials present in the DOM area. There is one large MIL pairing group (MIL 07099; n = 199; 9–14 Ma CRE age where measured) and one smaller pairing group with distinctly lower Cr2O3 in type II olivines (8 samples of unknown CRE age), and five unpaired or unique CO3s. Notably, the large DOM and MIL pairing groups have 9–16 Ma exposure ages that could have been delivered in a single large fall event spanning ~200 km, two separate falls that were ejection paired, or two separate falls from two separate ejections. Finally, we recommend reclassifying several CO3 to CM2 based on new data and that from previous studies.