¹Nancy N. Elewa, ¹J. M. Cadogan
Hyperfine Interactions 238, 4 Link to Article [https://doi.org/10.1007/s10751-016-1350-1]
¹School of Physical, Environmental and Mathematical Sciences The University of New South Wales at the Australian Defence Force Academy Canberra Australia

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¹J. Galazka-Friedman, ²M. Woźniak, ¹P. Duda, ¹P. Rzepecka, ¹M. Jakubowska, ³Ł. Karwowski
Hyperfine Interactions 238, 67 Link to Article [https://doi.org/10.1007/s10751-017-1439-1]
¹Faculty of Physics Warsaw University of Technology Warsaw Poland
²Faculty of Biology University of Warsaw Warsaw Poland
³Faculty of Earth Sciences University of Silesia Sosnowiec Poland

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¹Nao Nakanishi,¹Tetsuya Yokoyama,¹Satoki Okabayashi,²Tomohiro Usui,^1,3Hikaru Iwamori
Meteoritics & Planetary Science (in Press) Link to Article [DOI: 10.1111/maps.13050]
¹Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo, Japan
²Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo, Japan
³Department of Solid Earth Geochemistry, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan
Published by arrangement with John Wiley & Sons

We report Os isotope compositions of metal grains in two CBa chondrites (Bencubbin and Gujba) determined using a micromilling sampling coupled with thermal ionization mass spectrometry, together with the abundances of major and trace siderophile elements obtained by electron probe microanalysis and femtosecond laser ablation inductively coupled plasma–mass spectrometry. The CBa metal grains presented 187Os/188Os ratios akin to carbonaceous chondrites with limited variations (0.1257–0.1270). Most of the CBa metal grains were scattered along a 187Re-187Os reference isochron of IIIAB iron meteorites, indicating that the CBa metals experienced limited Re-Os fractionation at the time of their formation. The Re/Os ratios of sampling spots for the CBa metals, recast from the observed 187Os/188Os ratios, had a positive correlation with their Os/Ir ratios. In addition, the metal grains showed a positive correlation in a Pd/Fe versus Ni/Fe diagram. These correlations suggest that the CBa metal grains have formed via equilibrium condensation or evaporation from a gaseous reservoir at ~10−4 bar with enhanced metal abundances. Compared to the Bencubbin metals, the Gujba metals are characterized by having systematically lower Pd/Fe and Ni/Fe ratios that span subchondritic values. Such a difference was most likely induced by the compositionally heterogeneous impact plume from which the metals were condensed.

^1,2Hitesh G. Changela,^3,4Corentin Le Guillou,⁴Sylvain Bernard,⁵Adrian J. Brearley
Meteoritics & Planetary Science (in Press) Link to Article [DOI: 10.1111/maps.13045]
¹Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, USA
²Key Laboratory for Earth & Planetary Physics, Institute of Geology & Geophysics, Chinese Academy of Sciences, Beijing, China
³Unité matériaux et Transformation (UMET), CNRS UMR 8207, Université Lille1, Villeneuve D’Ascq, France
⁴Institut de Minéralogie, de physique des matériaux et de Cosmochimie (IMPMC), Sorbonne Université, Paris 06, IRD CNRS UMR 206, Paris, France
⁵Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, USA
Published by arrangement with John Wiley & Sons

The morphology, molecular composition, and distribution of organic matter (OM) were investigated in a suite of CR chondrites to better constrain its hydrothermal evolution. Multiple focused ion beam sections were extracted from the matrices of seven CR chondrites. Scanning transmission X-ray microscopy and transmission electron microscopy reveal OM ubiquitously distributed across the CR matrices. OM mainly occurs as either discrete submicron rounded or irregularly shaped vein-like particles. Two spectral populations of organic particles were identified by carbon K-edge X-ray absorption near edge structure (XANES): the most abundant one, similar to insoluble organic matter (IOM) residues, contains aromatic, carbonyl, and carboxylic groups. The second population is more aromatic-rich and lacks a distinctive carbonyl peak. An additional, ubiquitous organic component occurs associated with amorphous silicates and phyllosilicates. Less aromatic but aliphatic- and carboxylic-rich, this diffuse OM is interpreted as the result of the redistribution of organic compounds by aqueous fluids. The most altered CR1 GRO 95577 contains a more mature OM and highly aliphatic- and carboxylic-rich diffuse OM. This evolution, from the CR2s to the CR1, is comparable to that of terrestrial gas shale maturation involving cracking reactions, releasing bitumen-like, aliphatic-, and carboxylic-rich compounds, and aromatic residues. Our observations support the accretion of soluble OM and its later polymerization to IOM, as well as the maturation of IOM and its partial oxidation, releasing mobile compounds. The differences in GRO 95577 are clearly attributable to the hydrothermal episode(s), but the relative role of water and temperature on the evolution of OM remains elusive.

^1,4J.Aramendia, ^1,4L.Gomez-Nubla, ^1,4K.Castro, ^1,4S.Fdez-Ortiz de Vallejuelo, ^1,4G.Arana, ^1,4M.Maguregui, ^2,4V.G.Baonza, ^3,4J.Medina, ^3,4F.Rull, ^1,4J.M.Madariaga
TrAC Trends in Analytical Chemistry 98, 36-46 Link to Article [https://doi.org/10.1016/j.trac.2017.10.018]
¹Department of Analytical Chemistry, University of the Basque Country (UPV/EHU), P.O. Box 644, E-48080 Bilbao, Spain
²Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense, E-28040 Madrid, Spain
³Unidad Asociada UVA-CSIC al Centro de Astrobiología, University of Valladolid, Parque Tecnológico Boecillo, E-47151 Valladolid, Spain
⁴Spanish Science Team of the RLS Instrument, Exomars 2020 Mission of ESA to Mars, Spain

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¹Mehmet Yesiltas
Spectrochmica Acta Part A: Molecular and Biomolecular Spectroscopy 194, 92-101 Link to Article [https://doi.org/10.1016/j.saa.2018.01.021]
¹Faculty of Aeronautics and Space Sciences, Kirklareli University, Kirklareli 39000, Turkey

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^1,2Karel Lietaert, ¹Lore Thijs, ¹Bram Neirinck, ^2,3Thomas Lapauw,⁴Brian Morrison, ⁵Chris Lewicki, ¹Jonas Van Vaerenbergh
Acta Astronautica 143, 76-81 Link to Article [https://doi.org/10.1016/j.actaastro.2017.11.027]
¹3D Systems LayerWise NV, Grauwmeer 14, 3001 Leuven, Belgium
²KU Leuven Department of Materials Engineering, Kasteelpark Arenberg 44 pb2450, 3001 Leuven, Belgium
³Belgian Nuclear Research Centre SCK-CEN, Boeretang 200, 2400 Mol, Belgium
⁴ATI Powder Metals Robinson Operations, 6515 Steubenville Pike, Pittsburgh, PA 15205-1005, USA
⁵Planetary Resources, Inc., 6742 185th Ave, NE Redmond, WA 98052, USA

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^1,2Xiaojia Zeng,³Katherine H. Joy,^1,4Shijie Li,³John F. Pernet-Fisher,¹Xiongyao Li,³Dayl J. P. Martin,¹Yang Li,⁵Shijie Wang
Meteoritics & Planetary Science (in Press) Link to Article [DOI: 10.1111/maps.13049]
¹Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
²University of Chinese Academy of Sciences, Beijing, China
³School of Earth and Environmental Sciences, University of Manchester, Manchester, UK
⁴Key Laboratory of Lunar and Deep Space Exploration, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China
⁵State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
Published by arrangement with John Wiley & Sons

This study presents the petrography, mineralogy, and bulk composition of lunar regolith breccia meteorite Northwest Africa (NWA) 7948. We identify a range of lunar lithologies including basaltic clasts (very low-titanium and low-titanium basalts), feldspathic lithologies (ferroan anorthosite, magnesian-suite rock, and alkali suite), granulites, impact melt breccias (including crystalline impact melt breccias, clast-bearing impact melt breccias, and glassy melt breccias), as well as regolith components (volcanic glass and impact glass). A compositionally unusual metal-rich clast was also identified, which may represent an impact melt lithology sourced from a unique Mg-suite parent rock. NWA 7948 has a mingled bulk rock composition (Al₂O₃ = 21.6 wt% and FeO = 9.4 wt%) and relatively low concentrations of incompatible trace elements (e.g., Th = 1.07 ppm and Sm = 2.99 ppm) compared with Apollo regolith breccias. Comparing the bulk composition of the meteorite with remotely sensed geochemical data sets suggests that the sample was derived from a region of the lunar surface distal from the nearside Th-rich Procellarum KREEP Terrane. Our investigations suggest that it may have been ejected from a nearside highlands-mare boundary (e.g., around Mare Crisium or Orientale) or a cryptomare region (e.g., Schickard-Schiller or Mare smythii) or a farside highlands-mare boundary (e.g., Mare Australe, Apollo basin in the South Pole–Aitken basin). The distinctive mineralogical and geochemical features of NWA 7948 suggest that the meteorite may represent lunar material that has not been reported before, and indicate that the lunar highlands exhibit wide geological diversity.

¹G. Thangjam,¹A. Nathues,¹T. Platz,¹M. Hoffmann,²E. A. Cloutis,³K. Mengel,⁴M. R. M. Izawa,²D. M. Applin
Meteoritics & Planetary Science (in Press) Link to Article [DOI: 10.1111/maps.13044]
¹Max Planck Institute for Solar System Research, Goettingen, Germany
²University of Winnipeg, Winnipeg, Manitoba, Canada
³IELF, TU Clausthal, Clausthal-Zellerfeld, Germany
⁴Institute for Planetary Materials, Okayama University, Misasa, Misasa, Tottori, Japan
Published by arrangement with john Wiley & Sons

Variations and spatial distributions of bright and dark material on dwarf planet Ceres play a key role in understanding the processes that have led to its present surface composition. We define limits for “bright” and “dark” material in order to distinguish them consistently, based on the reflectance of the average surface using Dawn Framing Camera data. A systematic classification of four types of bright material is presented based on their spectral properties, composition, spatial distribution, and association with specific geomorphological features. We found obvious correlations of reflectance with spectral shape (slopes) and age; however, this is not unique throughout the bright spots. Although impact features show generally more extreme reflectance variations, several areas can only be understood in terms of inhomogeneous distribution of composition as inferred from Dawn Visible and Infrared Spectrometer data. Additional material with anomalous composition and spectral properties are rare. The identification of the composition and origin of the dark, particularly the darkest material, remains to be explored. The spectral properties and the morphology of the dark sites suggest an endogenic origin, but it is not clear whether they are more or less primitive surficial exposures or excavated subsurface but localized material. The reflectance, spectral properties, inferred composition, and geologic context collectively suggest that the bright and dark material tends to gradually change toward the average surface over time. This could be because of multiple processes, i.e., impact gardening/space weathering, and lateral mixing, including thermal and aqueous alteration, accompanied by changes in composition and physical properties such as grain size, surface temperature, and porosity (compaction).

¹Ming-Chang Liu, ¹Kevin D. McKeegan, ¹T. Mark Harrison, ¹George Jarzebinski, ¹Lvcian Vltava
International Journal of Mass Spectrometry 424, 1-9 Link to Article [https://doi.org/10.1016/j.ijms.2017.11.007]
¹Department of Earth, Planetary, and Space Sciences, UCLA, United States

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