¹G.J.MacPherson,²A.N.Krot,³N.T.Kita,⁴E.S.Bullock,²K.Nagashima,^3,5T.Ushikubo,^1,6M.A.Ivanova
Geochimica et Cosmochimica Acta (in Press) lIk to Article [https://doi.org/10.1016/j.gca.2021.12.033]
¹Dept. of Mineral Sciences, Museum of Natural History, Smithsonian Institution, Washington, DC, USA 20560
²Hawai’i Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
³WiscSIMS, Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53706
⁴Carnegie Institution for Science, Earth and Planets Laboratory, 5241 Broad Branch Rd., N.W., Washington, DC 20015, USA
⁵Kochi Institute for Core Sample Research, JAMSTEC, Nankoku, Kochi 783-8502, Japan
⁶Vernadsky Institute, Kosygin St. 19, Moscow, Russia
Copyright Elsevier

Five Type A CAIs from three CV3 chondrites (Vigarano, Northwest Africa 3118, Allende), which differ in age by no more than ∼10⁵ years, show mineralogical and textural evidence of gradual transition into Type Bs, indicating that Type B inclusions formed by evolution of Type A CAIs in the solar nebula. This model differs from the conventional condensation model in which aggregates of condensate grains form different kinds of CAIs depending on the relative populations of different kinds of grains. In our model the pyroxene forms nearly isochemically by reaction of perovskite with melilite under highly reducing conditions, and the reaction may be triggered by influx of hydrogen from the gas. Anorthite requires the addition of silica from the gas, and originally forms as veins and reaction rims on gehlenitic melilite within Fluffy Type As. Later partial re-melting of these assemblages results in the formation of poikilitic pyroxene and anorthite that enclose rounded (partially melted) tablets of melilite. Oxygen isotopes in four of the CAIs support the formation of Ti-rich ¹⁶O-depleted pyroxene from ¹⁶O-depleted perovskite, but not in the fifth CAI. An alternative possibility is that Ti-rich ¹⁶O-depleted pyroxene is the result of later solid-state exchange that preferentially affects the most Ti-rich pyroxene. Regardless of the origin of the ¹⁶O-depleted pyroxene, we give a model for nebular reservoir evolution based on sporadic FU-Orionis flare-ups in which the ¹⁶O-rich region near the proto-Sun fluctuated in size depending on whether the proto-Sun was in flare-up stage or quiescent.

¹Junya MATSUNO,^1,2,3Akira TSUCHIYAMA,⁴Akira MIYAKE,⁵Keiko NAKAMURA-MESSENGER,^5,6Scott MESSENGER
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.12.031]
¹Research Organization of Science and Technology, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-7, Japan
²CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (CAS), Guangzhou 510640, China
³CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
⁴Division of Earth and Planetary Sciences, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto 606-8502, Japan
⁵Johnson Space Center, NASA, Houston, TX 77058, United States
⁶Present address: Blue 22 Software, Houston, TX
Copyright Elsevier

GEMS (Glass with Embedded Metal and Sulfides) grains found in interplanetary dust particles are considered one of the most primitive materials in the Solar System, yet questions remain on how they formed. It has been suggested that GEMS grains are products of radiation processing and amorphization of sulfide and silicate mineral grains in the interstellar medium. Alternatively, GEMS grains are proposed to be disequilibrium condensation products in late-stage protosolar disks. We examined the 3D distributions of elements and inclusions within GEMS grains using TEM (transmission electron microscopic)-tomography to better constrain their possible formation processes. We found some core-shell particles composed of metals and amorphous silicates and observed a binary distribution of Mg/Si in amorphous silicates of GEMS grains. These properties are highly similar to the features of experimental condensation products. Furthermore, the location of sulfides only on the surface of GEMS and their larger sizes than metals are also consistent with the condensation experiments, where sulfides formed by sulfidation of metal grains with S-bearing gas species. Textures showing aggregation and possible coalescence of primary grains were also observed. Therefore, we conclude that GEMS grains are condensates from gas at high temperatures and some of them were aggregated.

¹Mehmet Yesiltas,²Thimothy D. Glotch,^3,4Melike Kaya
ACS Earth and Space Chemistry 5, 3281-3296 Link to Article [https://doi.org/10.1021/acsearthspacechem.1c00290]
¹Faculty of Aeronautics and Space Sciences, Kirklareli University, Kirklareli 39100, Turkey
²Department of Geosciences, Stony Brook University, Stony Brook, New York 11794, United States
³Institute of Acceleration Technologies, Ankara University, Ankara 06830, Turkey
⁴Turkish Accelerator and Radiation Laboratory (TARLA), Ankara 06830, Turkey

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^1,2Jon M. Friedrich,¹Matthiew M. Chen,¹Stephanie A. Giordano,¹Olivia K. Matalka,¹Juliette W. Strasser,¹Kirstin A. Tamucci,³Mark L. Rivers,^2,4,5Denton S. Ebel
Microscopy Research & Technique (in Press) Link to Article [https://doi.org/10.1002/jemt.24043]
¹Department of Chemistry, Fordham University, Bronx, New York, USA
²Department of Earth and Planetary Sciences, American Museum of Natural History, New York, New York, USA
³Center for Advanced Radiation Sources, University of Chicago, Argonne, Illinois, USA
⁴Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA
⁵Graduate Center of the City University of New York, New York, New York, USA

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¹Shigeko Togashi,¹Akihiko Tomiya,²Noriko T.Kita,^1,3Yuichi Morishita
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.12.029]
¹Geological Survey of Japan, AIST, Central 7, Higashi 1-1-1, Tsukuba 305-8567, Japan
²Department of Geoscience, University of Wisconsin, Madison 1215 W. Dayton Street Madison, WI 53706-1692, USA
³Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
Copyright Elsevier

The origin of the KREEP (K, Rare Earth Element and P)-rich component of the Mg-suite rocks of the Procellarum KREEP Terrane (PKT), one of three major lunar crustal terranes, is unclear. In an attempt to determine its origin, we estimated the composition of host magmas of plutonic rocks, including Mg-suite rocks and evolved rocks, from the PKT (PKT-host magmas) by using secondary ion mass spectrometry analyses of plagioclase. Calculated partition coefficients for Sr, Ba and Ti between plagioclase and melts, taking into account the anorthite content of plagioclase, temperature and bulk rock major-element compositions, were applied to determine parental magma compositions. The PKT-host magmas contained 160–360 ppm Sr, 520–7600 ppm Ba and 1.1–7.0 wt.% TiO2; most of them had higher Ti and Ba concentrations than KREEP basalts and high-K KREEP. We used phase relations based on the Rhyolite-MELTS algorithm to explore the evolution of the PKT-host magmas and KREEP basalts from two bulk silicate moon (BSM) starting compositions, a BSM with chondritic ratios of refractory elements, and a crustal-component-enriched BSM with non-chondritic ratios of refractory elements. We propose a three-stage evolution model. Stage-1: polybaric multi-step fractionation from a BSM magma to form ferroan anorthosite (FAN) crust and an evolved magma as the first KREEP-rich component (M0). Stage-2: assimilation and fractional crystallization (AFC) of M0, early cumulate and FAN associated with deep mantle overturn and impact events to form the PKT-host magmas, Mg-suite rocks and an evolved magma as the second KREEP-rich component (K0). Stage-3: further AFC cycles of K0, Mg-suite rocks or FAN associated with shallow mantle overturn and impact events to form KREEP basalts. This three-stage model for a crustal-component-enriched BSM with non-chondritic ratios of refractory elements (e.g., a sub-chondritic Ti/Ba ratio) reproduced the compositions of both the host magmas of FAN and the PKT-host magmas that fractionated to form the Mg-suite rocks and KREEP basalts of the PKT region. In particular, the model reproduced the high Ti and Ba contents of the PKT-host magmas we estimated from plagioclase composition. Variations of TiO2 and Ba contents (and hence Ti/Ba ratios) of the magmas were critical controls on their evolution.

¹François Robert,²Marc Chaussidon,²Adriana Gonzalez-Cano,¹Smail Mostefaoui
Proceeding sof the National Academy of Sciences of the United States of America (in Press) Link to Article [https://doi.org/10.1073/pnas.2114221118]
¹Institut Origine et Evolution, Muséum National d’Histoire Naturelle, Sorbonne Université, IMPMC-UMR 7590 CNRS, 75005 Paris, France;
²Université de Paris, Institut de Physique du Globe de Paris, CNRS, F-75005 Paris, France

Enrichment or depletion ranging from −40 to +100% in the major isotopes ¹⁶O and ²⁴Mg were observed experimentally in solids condensed from carbonaceous plasma composed of CO₂/MgCl₂/Pentanol or N₂O/Pentanol for O and MgCl₂/Pentanol for Mg. In NanoSims imaging, isotope effects appear as micrometer-size hotspots embedded in a carbonaceous matrix showing no isotope fractionation. For Mg, these hotspots are localized in carbonaceous grains, which show positive and negative isotopic effects so that the whole grain has a standard isotope composition. For O, no specific structure was observed at hotspot locations. These results suggest that MIF (mass-independent fractionation) effects can be induced by chemical reactions taking place in plasma. The close agreement between the slopes of the linear correlations observed between δ²⁵Mg versus δ²⁶Mg and between δ¹⁷O versus δ¹⁸O and the slopes calculated using the empirical MIF factor η discovered in ozone [M. H. Thiemens, J. E. Heidenreich, III. Science 219, 1073–1075; C. Janssen, J. Guenther, K. Mauersberger, D. Krankowsky. Phys. Chem. Chem. Phys. 3, 4718–4721] attests to the ubiquity of this process. Although the chemical reactants used in the present experiments cannot be directly transposed to the protosolar nebula, a similar MIF mechanism is proposed for oxygen isotopes: at high temperature, at the surface of grains, a mass-independent isotope exchange could have taken place between condensing oxides and oxygen atoms originated form the dissociation of CO or H₂O gas.

¹Van T. H. Phan,¹Rolando Rebois,¹Pierre Beck,¹Eric Quirico,¹Lydie Bonal,²Takaaki Noguchi
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13773]
¹Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), Université Grenoble Alpes/CNRS-INSU, UMR 5274, Grenoble, F-38041 France
²Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, Kitashirakawaoiwake-cho, Sakyo-ku, Kyoto, 606-8502 Japan
Published by arrangement with John Wiley & Sons

Meteorite matrices from primitive chondrites are an interplay of ingredients at the sub-µm scale, which requires analytical techniques with the nanometer spatial resolution to decipher the composition of individual components in their petrographic context. Infrared spectroscopy is an effective method that enables the probing of vibrations at the molecule atomic scale of organic and inorganic compounds but is often limited to a few micrometers in spatial resolution. To efficiently distinguish spectral signatures of the different constituents, we apply here nano-infrared spectroscopy (AFM-IR), based on the combination of infrared and atomic force microscopy, having a spatial resolution beyond the diffraction limits. Our study aims to characterize two chosen meteorite samples to investigate primitive material in terms of bulk chemistry (the CI chondrite Orgueil) and organic composition (the CR chondrite EET 92042). We confirm that this technique allows unmixing the IR signatures of organics and minerals to assess the variability of organic structure within these samples. We report an investigation of the impact of the widely used chemical HF/HCl (hydrogen fluoride/hydrochloric acid) extraction on the nature of refractory organics (insoluble organic matter [IOM]) and provide insights on the mineralogy of meteorite matrices from these two samples by comparing to reference (extra)terrestrial materials. These findings are discussed with a perspective toward understanding the impact of post-accretional aqueous alteration and thermal metamorphism on the composition of chondrites. Last, we highlight that the heterogeneity of organic matter within meteoritic materials extends down to the nanoscale, and by comparison with IOMs, oxygenated chemical groups are not affected by acid extractions.

^1,2Julia Semprich,^2,3Justin Filiberto,²Allan H. Treiman,¹Susanne P. Schwenzer
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13775]
¹AstrobiologyOU, School of Environment, Earth and Ecosystem Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA UK
²Lunar and Planetary Institute, USRA, 3600 Bay Area Blvd, Houston, Texas, 77058 USA
³Astromaterials Research and Exploration Science (ARES) Division, XI3, NASA Johnson Space Center, Houston, Texas, 77058 USA
Published by arrangement with John Wiley & Sons

Low-grade metamorphic hydrous minerals and carbonates occur in various settings on Mars and in Martian meteorites. We present constraints on the stability of prehnite, zeolites, serpentine, and carbonates by modeling the influence of H2O-CO2 fluids during low-grade metamorphism in the Martian crust using compositions of a Martian basalt and an ultramafic cumulate. In basaltic compositions with 5 wt% fluid, our models predict prehnite in less oxidized, CO2-poor conditions (≤0.44 mol kg−1 CO2) on warmer geotherms of 20 °C km−1. At fluid-saturated conditions, epidote and laumontite are replaced by quartz, calcite, chlorite, and muscovite. In ultramafic compositions with 5 wt% fluid, antigorite (serpentine) is stable at CO2-poor conditions of ≤0.33 mol kg−1, while talc forms at 0.05–0.56 mol kg−1 CO2. At fluid-saturated conditions, antigorite is replaced by talc and chlorite, and at higher X(CO2) by magnesite and quartz. Our models therefore suggest that prehnite, zeolites, and serpentine have formed in a CO2-poor environment on Mars implying that fluids during their formation either did not contain high amounts of CO2 or had degassed CO2. Carbonates and potentially talc would have formed in the presence of a CO2-bearing fluid and therefore at different alteration stages than for prehnite, zeolites, and serpentine either in the same hydrothermal event during which the fluid composition changed gradually due to cooling and precipitation or by separate and successive alteration events with fluids of different compositions.

¹Maxim Isachenkov,¹Svyatoslav Chugunov,²Zoe Landsman,¹Iskander Akhatov,²Anna Metke,¹Andrey Tikhonov,¹Igor Shishkovsky
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114873]
¹Skolkovo Institute of Science and Technology, Center for Design, Manufacturing, and Materials, 30 Bolshoy boulevard, bld, 1121205 Moscow, Russian Federation
²CLASS Exolith Lab, Florida Space Institute, 12354 Research Parkway, Orlando, FL 32826, United States of America
Copyright Elsevier

Lunar regolith is the most critical material for the in-situ resource utilization in the crewed Moon exploration missions. This natural material can be utilized for the additive manufacturing of concrete or ceramic parts on the Moon’s surface to support permanent human presence on the surface of Earth’s natural satellite. Due to the scarcity of regolith on Earth, its simulants are used in lab research to prepare the technology for Moon missions. The present study is devoted to the characterization of lunar regolith simulant material, recently developed by the University of Central Florida, that is considered as a suitable material for regolith-focused additive manufacturing technologies. This paper describes the characterization of the LHS-1 and LMS-1 simulants using XRF, XRD, SEM, EDX, DTA, TGA, UV/Vis/NIR spectroscopy, and Laser diffractometry methods to provide data on their mineral, chemical, and fractional composition, as well as, on their morphology and optical properties. The results were compared to the data of the previously developed simulants and the original lunar samples delivered by Apollo and Luna missions. It was found that LHS-1 and LMS-1 simulants well mimic the primary properties of the original lunar regolith and can be potentially used for ISRU research tasks.

¹Emanuele Plebani,²Bethany L.Ehlmann,^2,3Ellen K.Leask,⁴Valerie K.Fox,¹M. Murat Dundar
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114849]
¹Computer and Information Sciences Department, Indiana University – Purdue University, Indianapolis, 46202, IN, USA
²Div. of Geological & Planetary Sciences, California Institute of Technology, Pasadena, 91125, CA, USA
³John Hopkins University Applied Physics Laboratory, Laurel, 20723, MD, USA
⁴Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, 55455, MN, USA
Copyright Elsevier

Hyperspectral images collected by remote sensing have played a significant role in the discovery of aqueous alteration minerals, which in turn have important implications for our understanding of the changing habitability on Mars. Traditional spectral analyses based on summary parameters have been helpful in converting hyperspectral cubes into readily visualizable three channel maps highlighting high-level mineral composition of the Martian terrain. These maps have been used as a starting point in the search for specific mineral phases in images. Although the amount of labor needed to verify the presence of a mineral phase in an image is quite limited for phases that emerge with high abundance, manual processing becomes laborious when the task involves determining the spatial extent of detected phases or identifying small outcrops of secondary phases that appear in only a few pixels within an image. Thanks to extensive use of remote sensing data and rover expeditions, significant domain knowledge has accumulated over the years about mineral composition of several regions of interest on Mars, which allow us to collect reliable labeled data required to train machine learning algorithms. In this study we demonstrate the utility of machine learning in two essential tasks for hyperspectral data analysis: nonlinear noise removal and mineral classification. We develop a simple yet effective hierarchical Bayesian model for estimating distributions of spectral patterns and extensively validate this model for mineral classification on several test images. Our results demonstrate that machine learning can be highly effective in exposing tiny outcrops of specific phases in orbital data that are not uncovered by traditional spectral analysis. We package implemented scripts, documentation illustrating use cases, and pixel-scale training data collected from dozens of well-characterized images into a new toolkit. We hope that this new toolkit will provide advanced and effective processing tools and improve community’s ability to map compositional units in remote sensing data quickly, accurately, and at scale.