^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.

^1,2Meng-Hua Zhu,^2,3,4Natalia Artemieva,⁵Alessandro Morbidelli,⁶Qing-Zhu Yin,⁷Harry Becker,^2,7Kai Wünnemann
Nature 571, 226–229 Link to Article [DOI https://doi.org/10.1038/s41586-019-1359-0]
¹State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Taipa, Macau, China
²Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany
³Planetary Science Institute, Tucson, AZ, USA
⁴Institute of Geosphere Dynamics, RAS, Moscow, Russia
⁵Département Lagrange, University of Nice–Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, Nice, France
⁶Department of Earth and Planetary Sciences, University of California at Davis, Davis, CA, USA
⁷Institute für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany

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

^1,2Christoph Burkhardt,² Nicolas Dauphas,³ Ulrik Hans,⁴Bernard Bourdon,¹Thorsten Kleine
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2019.07.003]
¹Institut für Planetologie, University of Münster, Wilhelm Klemm-Straße 10, D-48149 Münster, Germany
²Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago, Illinois 60637, USA
³EMPA, Laboratory for Advanced Materials and Surfaces, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
⁴Laboratoire de Géologie de Lyon, ENS Lyon, CNRS and Université Claude Bernard Lyon 1, 69364 Lyon cedex 07, France
Copyright Elsevier

Isotope anomalies among planetary bodies provide key constraints on planetary genetics and the Solar System’s dynamical evolution. However, to unlock the full potential of these anomalies for constraining the processing, mixing, and transport of material in the disk it is essential to identify the main components responsible for producing planetary-scale isotope variations, and to investigate how they relate to the isotopic heterogeneity inherited from the Solar System’s parental molecular cloud. To address these issues we measured the Ti and Sr isotopic compositions of Ca,Al-rich inclusions (CAIs) from the Allende CV3 chondrite, as well as acid leachates and an insoluble residue from the Murchison CM2 chondrite, and combine these results with literature data for presolar grains, hibonites, chondrules, and bulk meteorites. Our analysis reveals that the internal mineral-scale nebular isotopic heterogeneity as sampled by leachates and presolar grains is largely decoupled from the planetary-scale isotope anomalies as sampled by bulk meteorites. We show that variable admixing of CAI-like refractory material to an average inner solar nebula component can explain the planetary-scale Ti and Sr isotope anomalies and the elemental and isotopic difference between non-carbonaceous (NC) and carbonaceous (CC) nebular reservoirs for these elements.
Combining isotope anomaly data for a large number of elements (Ti, Sr, Ca, Cr, Ni, Zr, Mo, Ru, Ba, Nd, Sm, Hf, W, and Os) reveals that the offset of the CC from the NC reservoir towards the composition of CAIs is a general trend and not limited to refractory elements. This implies that the CC reservoir is the product of mixing between NC material and a reservoir (called IC for Inclusion-like Chondritic component) whose isotopic composition is similar to that of CAIs, but whose chemical composition is similar to bulk chondrites. In our preferred model, the distinct isotopic compositions of these two nebular reservoirs reflect an inherited heterogeneity of the solar system’s parental molecular cloud core, which therefore has never been fully homogenized during collapse. Planetary-scale isotopic anomalies are thus caused by variable mixing of isotopically distinct primordial disk reservoirs, the selective processing of these reservoirs in different nebular environments, and the heterogeneous distribution of the thereby forming nebular products.

¹Robbin Visser,¹Timm John,²Markus Patzek,²Addi Bischoff,³Martin J.Whitehouse
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2019.06.046]
¹Freie Universität Berlin, Institut für Geologische Wissenschaften Berlin, Germany
²Institut für Planetologie, WWU Münster, Münster, Germany
³Swedish Museum of Natural History, Stockholm, Sweden
Copyright Elsevier

Deciphering aspects of the solar system’s formation process and the origin of planetary bodies can be achieved by examining primitive solar system materials, as these materials reflect the early solar system composition and may represent the building blocks of planetary bodies. Along these lines, knowing the original composition of carbonaceous chondrite meteorites is a valuable asset for determining the conditions in the parent bodies where they formed. Therefore, to determine the key characteristics of the parent bodies from which the carbonaceous chondrites and primitive materials are derived, we examined chemical and sulfur isotope compositions of sulfides in CM, CI and C2ung carbonaceous chondrites as well as from CM- and CI-like volatile-rich clasts; such an investigation allows us to explore the origin of these sulfides and to determine the primordial S composition of their parent body source region. In this study, sulfides from 7 CM, CI, and C2ung carbonaceous chondrites and 16 chondritic and achondritic breccias containing volatile-rich clasts were analyzed by electron microprobe and SIMS. Different sulfides were found, which shows evidence of different formation origins. Based on compositions and exsolution textures, we suggest that one fraction of the sulfides in both clasts and chondrites formed at high temperatures prior to incorporation into the parent body. The other sulfides most likely have a secondary origin and precipitated during fluid–rock interaction. Furthermore, differences in the S isotopic signature of the sulfides in chondrites correlate with the degree of aqueous alteration of the carbonaceous host rocks (CM or CI). Studying the sulfides of the volatile-rich clasts in brecciated chondrites and achondrites, a similar fractionation cannot be seen. Even though the mineralogy of CI chondrites and CI-like clasts is similar, the sulfides in CI chondrites appear to be enriched in heavy isotopes compared to those in the clasts (δ34S +1‰ (CI) vs -2‰ (CI-like clast). This could have been caused by different alteration conditions, or it represents a different sampling reservoir. In this study a large S isotopic fractionation between pentlandite and pyrrhotite was found in large primarily formed sulfides showing exsolution textures, indicating that pentlandite prefers to incorporate light S isotopes. Considering the S isotope composition of the exsolved phase which can be found in CM- and CI-like clasts, the pristine δ34S value of the original monosulfide solid solution (mss) is estimated to be ∼-2‰. This value possibly resembles the sampling reservoir from which the sulfides formed, indicating that both CM- and CI-like clasts derived from a similar reservoir, and this reservoir is different from the formation reservoir of the CI chondrites.

¹Imene Kerraouch,²Samuel Ebert,²Markus Patzek,²Addi Bischoff,³Michael E.Zolensky,⁴Andreas Pack,^6,7 Philippe Schmitt-Kopplin,¹Djelloul Belhai,¹Abderrahmane Bendaoud,⁷Loan Le
Geochemistry (Chemie der Erde) (in Press) Link to Article [https://doi.org/10.1016/j.chemer.2019.06.002]
¹LGGIP, FSTGAT, Université des Sciences et de la Technologie Houari Boumediene, Alger, Algeria
²Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm Str. 10, D-48149 Münster, Germany
³ARES, NASA Johnson Space Center, Houston, TX, USA
⁴Universität Göttingen, Geowissenschaftliches Zentrum, Goldschmidtstr. 1, D-37077 Göttingen, Germany
⁵Helmholtz-Zentrum, München, German Research Center for Environmental Health, Analytical BioGeoChemistry, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
⁶Chair of Analytical Food Chemistry, Technische Universität München, D-85354 Freising-Weihenstephan, Germany
⁷Jacobs ESCG, Houston, TX 77058, USA
Copyright Elsevier

The main mineralogical characteristics of a large light-colored clast within the Murchison CM breccia are discussed in detail including data on the mineralogy, bulk chemistry, organics, and oxygen isotopes. Petrographic study shows that the white clast consists of two areas with different granoblastic textures: (1) a coarse-grained (average grain size: ˜200 μm) and (2) a fine-grained lithology (average grain-size: ˜20 μm). The Fa-content of olivine in the clast is the same as Fa within olivine from Rumuruti (R) chondrites (Fa: ˜38 mol%); however, the concentrations of the elements Ni and Ca in olivine are significantly different. The fragment also contains Ca-rich pyroxene, ˜An_30-38-plagioclase/maskelynite, Cr-rich spinel, several sulfide phases, a nepheline-normative glass, and traces of merrillite and metal. The occurrence of maskelynite and nepheline-normative amorphous phase in restricted areas of the well-recrystallized rock may indicate remarkable P-T-excursions during shock metamorphism. The O-isotope composition of the clast falls below the terrestrial fractionation line (TFL), lying in the field of CM chondrites and is significantly different from data for bulk R chondrites. The study of the soluble organic matter revealed a highly-oxidized carbon chemistry and organomagnesium compounds reflecting high temperature and pressure processes.

¹B.Carry et al. (>10)
Astronomy & Astrophysics 623, A132 Link to Article [https://doi.org/10.1051/0004-6361/201833898]
¹Observatoire de la Côte d’Azur: Nice, Provence-Alpes-Côte d’Azu
Reproduced with permission (C) ESO

Context. CM-like asteroids (Ch and Cgh classes) are a major population within the broader C-complex, encompassing about 10% of the mass of the main asteroid belt. Their internal structure has been predicted to be homogeneous, based on their compositional similarity as inferred from spectroscopy and numerical modeling of their early thermal evolution.
Aims. Here we aim to test this hypothesis by deriving the density of the CM-like asteroid (41) Daphne from detailed modeling of its shape and the orbit of its small satellite.
Methods. We observed Daphne and its satellite within our imaging survey with the Very Large Telescope extreme adaptive-optics SPHERE/ZIMPOL camera and complemented this data set with earlier Keck/NIRC2 and VLT/NACO observations. We analyzed the dynamics of the satellite with our Genoid meta-heuristic algorithm. Combining our high-angular resolution images with optical lightcurves and stellar occultations, we determine the spin period, orientation, and 3D shape, using our ADAM shape modeling algorithm.
Results. The satellite orbits Daphne on an equatorial, quasi-circular, prograde orbit, like the satellites of many other large main-belt asteroids. The shape model of Daphne reveals several large flat areas that could be large impact craters. The mass determined from this orbit combined with the volume computed from the shape model implies a density for Daphne of 1.77 ± 0.26 g cm−3 (3 σ). This densityis consistent with a primordial CM-like homogeneous internal structure with some level of macroporosity (≈ 17%).
Conclusions. Based on our analysis of the density of Daphne and 75 other Ch/Cgh-type asteroids gathered from the literature, we conclude that the primordial internal structure of the CM parent bodies was homogeneous.

¹H.Haack et al (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13344]
¹Maine Mineral and Gem Museum, 99 Main St., Bethel, Maine, 04217 USA
Published by arrangement with John Wiley & Sons

On February 6, 2016 at 21:07:19 UT, a very bright fireball was seen over the eastern part of Denmark. The weather was cloudy over eastern Denmark, but many people saw the sky light up—even in the heavily illuminated Copenhagen. Two hundred and thirty three reports of the associated sound and light phenomena were received by the Danish fireball network. We have formed a consortium to describe the meteorite and the circumstances of the fall and the results are presented in this paper. The first fragment of the meteorite was found the day after the fall, and in the following weeks, a total of 11 fragments with a total weight of 8982 g were found. The meteorite is an unbrecciated, weakly shocked (S2), ordinary H chondrite of petrologic type 5/6 (Bouvier et al. 2017). The concentration of the cosmogenic radionuclides suggests that the preatmospheric radius was rather small ~20 cm. The cosmic ray exposure age of Ejby (83 ± 11 Ma) is the highest of an H chondrite and the second highest age for an ordinary chondrite. Using the preatmospheric orbit of the Ejby meteoroid (Spurny et al. 2017) locations of the recovered fragments, and wind data from the date of the fall, we have modeled the dark flight (below 18 km) of the fragments. The recovery location of the largest fragment can only be explained if aerodynamic effects during the dark flight phase are included. The recovery location of all other fragments are consistent with the dark flight modeling.