^1,2W. Fujiya,³P. Hoppe,⁴T. Ushikubo,^2,5K. Fukuda,⁶P. Lindgren,⁷M. R. Lee,^8,9M. Koike,^8,10K. Shirai,⁸Y. Sano
Nature Astronomy (in Press) Link to Article [https://doi.org/10.1038/s41550-019-0801-4]
¹Faculty of Science, Ibaraki University, Mito, Japan
²Department of Geoscience, University of Wisconsin-Madison, Madison, WI, USA
³Max Planck Institute for Chemistry, Mainz, Germany
⁴Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku, Japan
⁵Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan
⁶Department of Geology, Lund University, Lund, Sweden
⁷School of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK
⁸Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
⁹Department of Solar System Science, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
¹⁰International Coastal Research Center, Atmosphere and Ocean Research Institute, The University of Tokyo, Otsuchi, Japan

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¹Elishevah Kootenvan,^1,2Frédéric Moynier
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2019.07.022]
¹Université de Paris, Institut de Physique du Globe de Paris, CNRS UMR 7154, 1 rue Jussieu, 75238 Paris, France
²Institut Universitaire de France, Paris, France
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The potential complementarity between chondrules and matrix of chondrites, the Solar System’s building blocks, is still a highly debated subject. Complementary superchrondritic compositions of chondrite matrices and subchondritic chondrules may point to formation of these components within the same reservoir or, alternatively, to mobilization of elements during secondary alteration on chondrite parent bodies. Zinc isotope fractionation through evaporation during chondrule formation may play an important role in identifying complementary relationships between chondrules and matrix and is additionally a mobile element during hydrothermal processes. In an effort to distinguish between primary Zn isotope fractionation during chondrule formation and secondary alteration, we here report the Zn isotope data of five chondrule cores, five corresponding igneous rims and two matrices of the relatively unaltered Leoville CV3.1 chondrite. The detail required for these analyses necessitated the development of an adjusted Zn isotope analyses protocol outlined in this study. This method allows for the measurement of 5 ng Zn fractions, for which we have analyzed the isotope composition with an external reproducibility of 120 ppm. We demonstrate that we measure primary Zn isotope signatures within the sampled fractions of Leoville, which show negative δ66Zn values for the chondrule cores (δ66Zn = –0.43±0.14 ‰‰), more positive values for the igneous rims (δ66Zn = –0.01±0.30 ‰‰) and chondritic values for the matrix (δ66Zn = 0.19±0.14 ‰‰). In combination with elemental compositions and petrology of these chondrite fractions, we argue that chondrule cores, igneous rims and matrix could have formed within the same reservoir in the protoplanetary disk. The required formation mechanism involves Zn isotope fractionation through sulfide loss during chondrule core formation and concurrent thermal processing of matrix material. Depleted olivine-bearing grains representing this processed matrix would have accreted to the depleted chondrule cores and subsequently reabsorbed material (including 66Zn-rich) from a complementary volatile-rich gas, thereby forming the igneous rims. This would have allowed the rims to move towards an isotopically chondritic composition, similar to the non-processed matrix in Leoville. We note that Zn isotope analyses of components in other chondrites (f.e., CM, CO, EC) are necessary to identify if this complementarity relationship is generic or unique for each chondrite group. The development of a Zn isotope protocol for singularly small samples is a step forward in that direction.

¹Laurent Remusat,^2,3Jean-Yves Bonnet,¹Sylvain Bernard,⁴Arnaud Buch,³Eric Quirico
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2019.07.013]
¹Institut de Minéralogie, Physique des Matériaux et Cosmochimie (IMPMC), UMR CNRS 7590, Sorbonne Université, Muséum National d’Histoire Naturelle, 57 rue Cuvier, Case 52, 75231 Paris Cedex 5, France
²LATMOS-IPSL, Université Versailles St-Quentin, Sorbonne Université, CNRS UMR 8190, 78280 Guyancourt, France
³Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), UMR CNRS 5274, Université Grenoble Alpes, 38041 Grenoble, France
⁴Laboratoire Génie des Procédés et Matériaux (LGPM) CentraleSupelec, 8-10 rue Joliot-Curie 91190 Gif-sur-Yvette, France
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Organic matter contained in carbonaceous chondrites may have evolved due to aqueous and/or thermal evolution on the parent body. The thermal behavior of the insoluble organic matter (IOM) of the Orgueil meteorite was investigated. The evolutions of structural and molecular properties were assessed by Raman, infrared and XANES spectroscopies, the H- and N-isotopic compositions by NanoSIMS. The starting IOM is a disordered organic macromolecule presenting a high degree of cross-linking. Hydrogen and Nitrogen isotope distributions are heterogeneous with the occurrence of numerous micron-sized hot spots enriched in heavy isotopes of H or N. After 1 hour at 300°C, there is subtle modification of the structural ordering and the isotopic compositions. After 1 hour at 500°C, the structure evolves toward condensation. Indeed, FTIR and XANES data are consistent with a continuous evolution of the molecular structure toward an increase of aromatization, starting at 300°C and becoming more intense at 500°C. The bulk D-enrichment is significantly reduced and D-rich hot spots are lost at 500°C. The experimental evolution of the δD is consistent with observations of IOM isolated from lightly altered carbonaceous chondrites. In contrast, the ¹⁵N-rich hot spots seem insensitive to high temperature up to 500°C and bulk δ¹⁵N remains constant. The thermal evolution of H- and N- isotopes is decoupled, indicating that the D-rich and ¹⁵N-rich moieties exhibit different thermal recalcitrance.

¹Mancuso, S.,^1,2Taricco, C.,²Colombetti, P.,^1,2Rubinetti, S.,³Sinha, N.,⁴Bhandari, N.,
^1,2Barghini, D.,¹Gardiol, D.
Nuovo Cimento della Societa Italiana di Fisica C 42, Article number Y Link to Article [DOI: 10.1393/ncc/i2019-19043-8]
¹Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Torino – Strada Osservatorio 20, Pino Torinese, 10025, Italy
²Dipartimento di Fisica, Università di Torino -, Via P. Giuria 1, Torino, 10125, Italy
³Wentworth Institute of Technology, Boston, MA, United States

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^1,2Litasov, K.D.,³Ishikawa, A.,⁴Kopylova, A.G.,
¹Podgornykh, N.M.,¹Pokhilenko, N.P.
Doklady Earth Sciences 485, 381-385 Link to Article [DOI: 10.1134/S1028334X19040068]
¹Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russian Federation
²Novosibirsk State University, Novosibirsk, 630090, Russian Federation
³Tokyo Institute of Technology, Tokyo, 152-8550, Japan

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¹Ouknine, L.,¹Khiri, F.,¹Ibhi, A.,²Heikal, M.T.S.,³Saint-Gerant, T.,³Medjkane, M.
Journal of African Earth Sciences 158, 103551 Link to Article [DOI: 10.1016/j.jafrearsci.2019.103551]
¹Petrology, Metallogeny and Meteorites Team, Faculty of Sciences, Ibn Zohr University, Agadir, Morocco
²Geology Department, Faculty of Science, Tanta University, Egypt
³Identité et Différenciation Des Espaces, de L’environnement et des Sociétés (IDEES), Université de Caen, France

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¹Akira Yamaguchi,¹Makoto Kimura,^2,3Jean‐Alix Barrat,⁴Richard Greenwood
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13351]
¹National Institute of Polar Research, Tachikawa, Tokyo, 190‐8518 Japan
²Université Européenne de Bretagne, Lorient, France
³CNRS, UMR 6538 (Domaines Océaniques), U.B.O.‐I.U.E.M., Place Nicolas Copernic, 29280 Plouzané Cedex, France
⁴Planetary and Space Sciences, Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA UK
Published by arrangement with John Wiley & Sons

We performed a petrologic, geochemical, and oxygen isotopic study of the lowest FeO ordinary chondrite (OC), Yamato (Y) 982717. Y 982717 shows a chondritic texture composed of chondrules and chondrule fragments, and mineral fragments set in a finer grained, clastic matrix, similar to H4 chondrites. The composition of olivine (Fa_{11.17 ± 0.48 (1σ)}) and low‐Ca pyroxene (Fs_{11.07 ± 0.98 (1σ)}Wo_{0.90 ± 0.71(1σ)}) is significantly more magnesian than those of typical H chondrites (Fa_16.0‐20, Fs_14.5‐18.0), as well as other known low‐FeO OCs (Fa_12.8‐16.7; Fs_13‐16). However, the bulk chemical composition of Y 982717, in particular lithophile and moderately volatile elements, is within the range of OCs. The bulk siderophile element composition (Ni, Co) is within the range of H chondrites and distinguishable from L chondrites. The O‐isotopic composition is also within the range of H chondrites. The lack of reduction textures indicates that the low olivine Fa content and low‐Ca pyroxene Fs content are characteristics of the precursor materials, rather than the result of reduction during thermal metamorphism. We suggest that the H chondrites are more compositionally diverse than has been previously recognized.

¹Chi Ma,²Oliver Tschauner,^3,4Luca Bindi,¹John R. Beckett,^5,6Xiande Xie
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13349]
¹Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, 91125 USA
²Department of Geoscience, University of Nevada, Las Vegas, Nevada, 89154 USA
³Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via G. La Pira 4, I‐50121 Firenze, Italy
⁴CNR, Istituto di Geoscienze e Georisorse, Sezione di Firenze, Via G. La Pira 4, I‐50121 Firenze, Florence, Italy
⁵Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640 China
⁶Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Chinese Academy of Sciences, Guangzhou, 510640 China
Published by arrangement with John Wiley & Sons

A new high‐pressure silicate, (Mg,Fe,Si)2(Si,□)O4 with a tetragonal spinelloid structure, was discovered within shock melt veins in the Tenham and Suizhou meteorites, two highly shocked L6 ordinary chondrites. Relative to ringwoodite, this phase exhibits an inversion of Si coupled with intrinsic vacancies and a consequent reduction of symmetry. Most notably, the spinelloid makes up about 30–40 vol% of the matrix of shock veins with the remainder composed of a vitrified (Mg,Fe)SiO3 phase (in Tenham) or (Mg,Fe)SiO3‐rich clinopyroxene (in Suizhou); these phase assemblages constitute the bulk of the matrix in the shock veins. Previous assessments of the melt matrices concluded that majorite and akimotoite were the major phases. Our contrasting result requires revision of inferred conditions during shock melt cooling of the Tenham and Suizhou meteorites, revealing in particular a much higher quench rate (at least 5 × 103 K s−1) for veins of 100–500 μm diameter, thus overriding formation of the stable phase assemblage majoritic garnet plus periclase.

^1,2Claudia‐Corina Giese,²Inge Loes Ten Kate,²Oliver Plümper,²Helen E. King,³Christoph Lenting,^2,4,5Yang Liu,⁶Alexander G. G. M. Tielens
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13359]
¹Leiden Observatory, Faculty of Science, Leiden University, 2300 RA Leiden, the Netherlands
²Department of Earth Sciences, Faculty of Geosciences, Utrecht University, 3584 CD Utrecht, the Netherlands
³Steinmann‐Institut for Geology, Mineralogy und Palaeontology, University of Bonn, 53115 Bonn, Germany
⁴Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, the Netherlands
⁵Plymouth Electron Microscopy Centre, University of Plymouth, Devon, PL4 8AA Plymouth, UK
⁶Leiden Observatory, Faculty of Science, Leiden University, 2300 RA Leiden, the Netherlands
Published by arrangement with John Wiley & Sons

Large polycyclic aromatic hydrocarbons (PAHs) are an important component of the interstellar medium. PAHs have been identified in the soluble and insoluble matter of carbonaceous chondrites (CCs). Here, we study the evolution of PAHs under conditions relevant to the interiors of asteroids and compare our results to PAHs observed in CCs. We have performed long‐term and short‐term hydrothermal experiments, in which we exposed PAH‐mineral mixture analogs of meteorites to temperature conditions representative of those predicted for asteroids interiors. Our results show that small PAHs with melting points within the aqueous alteration temperature of CCs form carbonaceous spherules in the presence of water. In this work, we describe the microstructure and morphology of these spherules. We discuss the similarities and differences compared to globules isolated from CCs.

¹Tu-Han Luu,¹Remco C.Hin,¹Christopher D.Coath,¹Tim Elliott
Earth and Planetary Science Letters 522, 166-175 Link to Article [https://doi.org/10.1016/j.epsl.2019.06.033]´
¹Bristol Isotope Group, School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK
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