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
Copyright Elsevier

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

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

^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

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

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

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

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
Copyright Elsevier

¹Bruno Leonardo do Nascimento-Dias,¹Maria Beatriz Barbosa de Andrade,¹Zélia Maria da Costa Ludwig
International Journal of Astrobiology (in Press) Link to Article [DOI: https://doi.org/10.1017/S1473550419000041]
¹Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil

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

¹Logan M.Combs,¹Arya Udry,²Geoffrey H.Howarth,³Minako Righter,³Thomas J.Lapen,^4,5Juliane Gross,⁶Daniel K.Ross,¹Rachel R.Rahib,⁷James M.D.Day
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2019.07.001]
¹Department of Geoscience, University of Nevada Las Vegas, Las Vegas NV 89154, USA
²Department of Geological Sciences, University of Cape Town, Rondebosch 7701, South Africa
³Department of Earth and Atmospheric Sciences, University of Houston, Houston TX 77204, USA
⁴Department of Earth and Planetary Sciences, Rutgers University, Piscataway NJ 08854, USA
⁵Department of Earth and Planetary Sciences, The American Museum of Natural History, New York, NY10024, USA
⁶Jacobs-JETS/NASA Johnson Space Center, Houston TX 77058, USA
⁷Scripps Institution of Oceanography, University of California San Diego, La Jolla CA 92093, USA
Copyright Elsevier

The martian meteorite Northwest Africa (NWA) 10169 is classified as a member of the geochemically enriched poikilitic shergottites, based on mineral composition, Lu-Hf and Sm-Nd isotope systematics, and rare earth element (REE) concentrations. Similar to other enriched and intermediate poikilitic shergottites, NWA 10169 is a cumulate rock that exhibits a bimodal texture characterized by large pyroxene oikocrysts (poikilitic texture) surrounded by olivine-rich interstitial material (non-poikilitic texture). Olivine chadacrysts and pyroxene oikocrysts have higher Mg#s (molar Mg/Mg+Fe) than those in the interstitial areas, suggesting that the poikilitic texture represents early-stage crystallization and accumulation, as opposed to late-stage non-poikilitic (i.e., interstitial material) crystallization. Calculated oxygen fugacity values are more reduced (FMQ -2.3 ± 0.2) within the poikilitic regions, and more oxidized (FMQ -1.1 ± 0.1) within the interstitial areas, likely representing auto-oxidation and degassing during magma crystallization. Calculated parental melt compositions using olivine-hosted melt inclusions display a dichotomy between K-poor and K-rich melts, thus possibly indicating mixing of parental melt with K-rich melt. The 176Lu-176Hf crystallization age for NWA 10169 is 167 ± 31 Ma, consistent with the ages reported for other enriched shergottites. Based on the isochron initial 176Hf/177Hf value, the modeled source 176Lu/177Hf composition for NWA 10169 is 0.02748 ± 0.00037, identical within uncertainty to the source compositions of the enriched shergottites Shergotty, Zagami, LAR 06319, NWA 4468, and Roberts Massif (RBT) 04262, suggesting a shared, long-lived geochemical source, and distinct from the source of other enriched shergottites Los Angeles, NWA 856, and NWA 7320. This study reveals that at least two sources are responsible for the enriched shergottites, and that the martian mantle is more heterogeneous than previously thought. Additionally, the enriched shergottites, which share a source with NWA 10169, have consistent crystallization ages and magmatic histories, indicating that a common magmatic system on Mars is likely responsible for the formation of this group.