¹Evelyn Füri, ^1,2Marc Chaussidon, ¹Bernard Marty
¹Centre de Recherches Pétrographiques et Géochimiques, CNRS-UL, 15 rue Notre Dame des Pauvres, BP20, 54501 Vandoeuvre-lès-Nancy, France
²Now at Institut de Physique du Globe de Paris, CNRS, 1 rue Jussieu, 75005 Paris, France

Nitrogen and noble gas (Ne-Ar) abundances and isotope ratios, determined by CO2 laser extraction static mass spectrometry analysis, as well as Al-Mg and O isotope data from secondary ion mass spectrometry (SIMS) analyses, are reported for a type B calcium-aluminum-rich inclusion (CAI) from the CV3 chondrite NWA 8616. The high (26Al/27Al)i ratio of (5.06 ± 0.50) × 10-5 dates the last melting event of the CAI at View the MathML source39-99+109 ka after the “time zero”, limiting the period during which high-temperature exchanges between the CAI and the nebular gas could have occurred to a very short time interval. Partial isotopic exchange with a 16O-poor reservoir resulted in Δ17O > -5‰ for melilite and anorthite, whereas spinel and Al-Ti-pyroxene retain the inferred original 16O-rich signature of the solar nebula (Δ17O ⩽ -20 ‰). The low 20Ne/22Ne (⩽0.83) and 36Ar/38Ar (⩽0.75) ratios of the CAI rule out the presence of any trapped planetary or solar noble gases. Cosmogenic 21Ne and 38Ar abundances are consistent with a cosmic ray exposure (CRE) age of ∼14 to 20 Ma, assuming CR fluxes similar to modern ones, without any evidence for pre-irradiation of the CAI before incorporation into the meteorite parent body. Strikingly, the CAI contains 1.4 to 3.4 ppm N with a Δ15N value of +8 to +30 ‰. Even after correcting the measured Δ15N values for cosmogenic 15N produced in situ, the CAI is highly enriched in 15N compared to the protosolar nebula (Δ15NPSN = -383 ± 8 ‰; Marty et al., 2011), implying that the CAI-forming region was contaminated by 15N-rich material within the first 0.15 Ma of Solar System history, or, alternatively, that the CAI was ejected into the outer Solar System where it interacted with a 15N-rich reservoir.

Reference
Füri E, Chaussidon M, Marty B (2015) Evidence for an early nitrogen isotopic evolution in the solar nebula from volatile analyses of a CAI from the CV3 chondrite NWA 8616. Geochimica et Cosmochimica Acta (in Press)
Link to Article [doi:10.1016/j.gca.2015.01.004]

Copyright Elsevier

¹Vishnu Reddy et al. (>10)*
¹Planetary Science Institute, 1700 East Fort Lowell Road, Tucson, AZ 85719, USA
*Find the extensive, full author and affiliation list on the publishers Website

We explored the statistical and compositional link between Chelyabinsk meteoroid and potentially hazardous asteroid (86039) 1999 NC43 to investigate their proposed relation proposed by . First, using a slightly more detailed computation we confirm that the orbit of the Chelyabinsk impactor is anomalously close to the asteroid 1999 NC43. We find ∼(1-3) × 10-4 likelihood of that to happen by chance. Taking the standpoint that the Chelyabinsk impactor indeed separated from 1999 NC43 by a cratering or rotational fission event, we run a forward probability calculation, which is an independent statistical test. However, we find this scenario is unlikely at the ∼(10-3 -10-2) level. Secondly, we note that efforts to conclusively prove separation of the Chelyabinsk meteoroid from (86039) 1999 NC43 in the past needs to meet severe criteria: relative velocity ≃1-10 m/s or smaller, and ≃ 100 km distance (i.e. about the Hill sphere distance from the parent body). We conclude that, unless the separation event was an extremely recent event, these criteria present an insurmountable difficulty due to the combination of strong orbital chaoticity, orbit uncertainty and incompleteness of the dynamical model with respect to thermal accelerations. This situation leaves the link of the two bodies unresolved and calls for additional analyses. With that goal, we revisit the presumed compositional link between (86039) 1999 NC43 and the Chelyabinsk body. noted that given its Q-type taxonomic classification, 1999 NC43 may pass this test. However, here we find that while the Q-type classification of 1999 NC43 is accurate, assuming that all Q-types are LL chondrites is not. Our experiment shows that not all ordinary chondrites fall under Q-taxonomic type and not all LL chondrites are Q-types. Spectral curve matching between laboratory spectra of Chelyabinsk and 1999 NC43 spectrum shows that the spectra do not match. Mineralogical analysis of Chelyabinsk (LL chondrite) and (8) Flora (the largest member of the presumed LL chondrite parent family) shows that their olivine and pyroxene chemistries are similar to LL chondrites. Similar analysis of 1999 NC43 shows that its olivine and pyroxene chemistries are more similar to L chondrites than LL chondrites (like Chelyabinsk). Analysis of the spectrum using Modified Gaussian Model (MGM) suggests 1999 NC43 is similar to LL or L chondrite although we suspect this ambiguity is due to lack of temperature and phase angle corrections in the model. While some asteroid pairs show differences in spectral slope, there is no evidence for L and LL chondrite type objects fissioning out from the same parent body. We also took photometric observations of 1999 NC43 over 54 nights during two apparitions (2000, 2014). The lightcurve of 1999 NC43 resembles simulated lightcurves of tumblers in Short-Axis Mode (SAM) with the mean wobbling angle 20°-30°. The very slow rotation of 1999 NC43 could be a result of slow-down by the Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect. While, a mechanism of the non-principal axis rotation excitation is unclear, we can rule out the formation of asteroid in disruption of its parent body as a plausible cause, as it is unlikely that the rotation of an asteroid fragment from catastrophic disruption would be nearly completely halted. Considering all these facts, we find the proposed link between the Chelyabinsk meteoroid and the asteroid 1999 NC43 to be unlikely.

Reference
Reddy V (2015) Link between the potentially hazardous asteroid (86039) 1999 NC43 and the Chelyabinsk meteoroid tenuous. Icarus (in Press)
Link to Article [doi:10.1016/j.icarus.2015.01.006]

Copyright Elsevier

¹Brandon C. Johnson,²David A. Minton,²H. J. Melosh¹Maria T. Zuber
¹Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
²Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, Indiana 47907, USA

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

Reference
Johnson BC, Minton DA, Melosh HJ, Zuber MT (2015) Impact jetting as the origin of chondrules. Nature 517, 339–341

Link to Article [doi:10.1038/nature14105]

^1,2Hiroshi Takeda, ³Hiroshi Nagaoka, ^4,5Akira Yamaguchi, ⁶Yuzuru Karouji, ⁷Yuuki Yazawa
¹Department of Earth and Planetary Science, Graduate School of Sciences, University of Tokyo, Hongo 113-0033, Tokyo, Japan
²Forum Research, Chiba Institute of Technology, Narashino 275-0016, Chiba, Japan
³Research Institute for Science and Engineering, Waseda University, Shinjuku 169-8555, Tokyo, Japan
⁴National Institute of Polar Research, Tachikawa 190-8518, Tokyo, Japan
⁵Department of Polar Science, School of Multidisciplinary Sciences, Graduate University for Advanced Studies, Tachikawa 190-8518, Tokyo, Japan
⁶Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara 252-5210, Kanagawa, Japan
⁷Department of Life and Environmental Sciences, Chiba Institute of Technology, Narashino 275-0016, Chiba, Japan

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

Reference
Takeda H, Nagaoka H, Yamaguchi A, Karouji Y, Yazawa Y (2015) Mineralogy of some evolved LL chondrites with reference to asteroid materials and solar system Evolution. Earth, Planets and Space, 67:5
Link to Article [doi:10.1186/s40623-014-0167-x]

¹Robina Shaheen, ²Paul B. Niles, ^1,3Kenneth Chong, ⁴Catherine M. Corrigan ¹Mark H. Thiemens
¹Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92122;
²Astromaterials Research and Exploration Science, NASA Johnson Space Center, Houston, TX 77058;
³Department of Chemistry, California State Polytechnic University, Pomona, CA 91768; and
⁴Smithsonian Institution, Washington, DC 20004

Carbonate minerals provide critical information for defining atmosphere–hydrosphere interactions. Carbonate minerals in the Martian meteorite ALH 84001 have been dated to ∼3.9 Ga, and both C and O-triple isotopes can be used to decipher the planet’s climate history. Here we report Δ17O, δ18O, and δ13C data of ALH 84001 of at least two varieties of carbonates, using a stepped acid dissolution technique paired with ion microprobe analyses to specifically target carbonates from distinct formation events and constrain the Martian atmosphere–hydrosphere–geosphere interactions and surficial aqueous alterations. These results indicate the presence of a Ca-rich carbonate phase enriched in 18O that formed sometime after the primary aqueous event at 3.9 Ga. The phases showed excess 17O (0.7‰) that captured the atmosphere–regolith chemical reservoir transfer, as well as CO2, O3, and H2O isotopic interactions at the time of formation of each specific carbonate. The carbon isotopes preserved in the Ca-rich carbonate phase indicate that the Noachian atmosphere of Mars was substantially depleted in 13C compared with the modern atmosphere.

Reference
Shaheen R, Niles NB, Chong K, Corrigan CM, Thiemens MH (2015) Carbonate formation events in ALH 84001 trace the evolution of the Martian atmosphere. Proceedings of the National Academy of Sciences 112, 336-341;
Link to Article [doi:10.1073/pnas.1315615112]

¹Charles K. Shearer, ¹Stephen M. Elardo, ²Noah E. Petro, ³Lars E. Borg,¹Francis M. McCubbin
¹Institute of Meteoritics, Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, U.S.A.
²NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, U.S.A.
³Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California 94550, U.S.A.

The Mg-suite represents an enigmatic episode of lunar highlands magmatism that presumably represents the first stage of crustal building following primordial differentiation. This review examines the mineralogy, geochemistry, petrology, chronology, and the planetary-scale distribution of this suite of highlands plutonic rocks, presents models for their origin, examines petrogenetic relationships to other highlands rocks, and explores the link between this style of magmatism and early stages of lunar differentiation. Of the models considered for the origin of the parent magmas for the Mg-suite, the data best fit a process in which hot (solidus temperature at ≥2 GPa = 1600 to 1800 °C) and less dense (ρ ~3100 kg/m3) early lunar magma ocean cumulates rise to the base of the crust during cumulate pile overturn. Some decompressional melting would occur, but placing a hot cumulate horizon adjacent to the plagioclase-rich primordial crust and KREEP-rich lithologies (at temperatures of

Reference
Shearer CK, Elardo SM, Petro NE, Borg LE, McCubbin FM (2015) Origin of the lunar highlands Mg-suite: An integrated petrology, geochemistry, chronology, and remote sensing perspective. American Mineralogist, 100,294-325
Link to Article [doi: 10.2138/am-2015-4817]

Copyright: The Mineralogical Society of America

^1,4Michael J. Gaffey, ^2,4Vishnu Reddy, ^1,4Sherry-Fieber-Beyer ³Edward Cloutis
¹Space Studies Department, John D. Odegard School of Aerospace Sciences, University of North Dakota, Grand Forks, ND 58202-9008
²Planetary Science Institute, 1700 E Fort Lowell Rd, Suite 106, Tucson, AZ 85719
³Department of Geography, University of Winnipeg, 515 Portage Avenue, Winnipeg, Manitoba, Canada R3B 2E9
⁴Visiting Astronomer at the Infrared Telescope Facility, which is operated by the University of Hawaii under Cooperative Agreement No. NNX-08AE38A with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program

During a survey of the S-type asteroids, Gaffey et al. (1993) identified asteroid (354) Eleonora as anomalous with a 1 μm absorption feature ∼2.5 times stronger than any S-asteroid of comparable size. Subsequent investigation revealed significant differences in the 1 μm absorption feature between the visible & very near-infrared CCD spectra (λ < ∼1.0 μm) and other spectral data sets for this asteroid. There were also significant spectral differences among the several CCD survey spectra (SMASS-I, SMASS-II & S3OS2) of Eleonora. These differences could potentially arise from spectral variations across the asteroid surface, from observational phase angle differences, from surface temperature differences, from viewing geometry for a nonspherical body, or from the use of standard stars with deviated to different degrees from a true solar standard.

In June 2011 asteroid (354) Eleonora was observed over two nights using the NASA Infrared Telescope Facility (IRTF) at Mauna Kea Observatory in order to test these possible scenarios and to better understand the nature and history of Eleonora and its relationships to other asteroids and to the meteorites. Analysis of this data set has eliminated the following options as the cause of the differences in the 1 μm absorption feature within the CCD data sets and between the CCD data sets and the other spectral data: (1) rotational spectral variations; (2) variation in surface composition with latitude; (3) observation phase; (4) surface temperature variations with differing heliocentric distance in the asteroid’s elliptical orbit; (5) spectral effects of viewing geometry for a nonspherical body; and (6) differences in spectral standard stars. We conclude that none of the CCD spectra of (354) Eleonora are reliable, and that within the limits of their spectral coverage, analyses of the three CCD spectra would produce significantly different – and generally unreliable – indications of surface mineralogy. An effort needs to be made to determine whether “bad” CCD spectra are rare with the case of (354) Eleonora being an uncommon occurrence or whether there is a broader problem with the CCD asteroid survey data sets, and if so, how to identify the “bad” spectra..

While CCD Survey spectra show apparently irreconcilable differences, the near-infrared spectra of (354) Eleonora from various observers show only minor differences, primarily in the overall spectral slope, most of which can be attributed to slight differences in the standard stars used to calibrate the data.

In June 2011, 226 near-infrared (∼0.76 – 2.5 μm) spectra of (354) Eleonora were obtained using the SpeX instrument on the NASA Infrared Telescope Facility at Mauna Kea Observatory. These spectra were consistent with the six sets of NIR spectra obtained for Eleonora by previous observers. The primary variation observed in this new data set was an approximately 10% variation in spectral slope between ∼0.8 μm and ∼1.6 μm during the rotation period of the asteroid.

Mineralogically diagnostic spectral parameters extracted from this new data are most consistent with a surface assemblage of fine-grained intimately mixed olivine (∼60-70%, ∼Fo61-71) and low nickel (<∼7-8% Ni) NiFe metal. The Fo estimate is consistent with previous estimates (Fo66±5) by Sanchez et al. (2014), but not with the estimate (∼Fo90) of Sunshine et al. (2007). The surface assemblage appears to contain a small component (∼8-10%) of igneous pyroxene (weakly constrained at ∼Fs50Wo10). The parent lithology of the surface regolith may be similar to a pallasite assemblage, although none of the three known types of pallasites are good mineralogical matches.

Reference
Gaffey MJ, Reddy V, Sherry-Fieber-Beyer, Cloutis E (2014)Asteroid (354) eleonora: Plucking an odd duck. Icarus (in Press)
Link to Article [doi:10.1016/j.icarus.2014.12.036]

Copyright Elsevier

^1,2Grevesse, N., ³Scott, P., ⁴Asplund, M. ⁵Sauval, A.J
¹Centre Spatial de Liège, Université de Liège, avenue Pré AilyAngleur-Liège, Belgium
²Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 août, 17, B5CLiège, Belgium
³Department of Physics, Imperial College London, Blackett Laboratory, Prince Consort RoadLondon, United Kingdom
⁴Research School of Astronomy and Astrophysics, Australian National University, Cotter Rd.Weston Creek, ACT, Australia
⁵Observatoire Royal de Belgique, avenue circulaire, 3Bruxelles, Belgium

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

Reference
Grevesse N , Scott P, Asplund M, Sauval AJ (2014) The elemental composition of the Sun III. The heavy elements Cu to Th.
Astronomy and Astrophysics 573
Link to Article [DOI: 10.1051/0004-6361/201424111]

^1,2Usui, T., ²Jones, J. H. ²Mittlefehldt, D. W.
¹Astromaterials Research & Exploration Science Directorate, Johnson Space Center, NASA, Houston, Texas, USA
²Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo, Japan

Melting experiments of a synthesized, alkali-bearing, H-chondrite composition were conducted at ambient pressure with three distinct oxygen fugacity conditions (IW-1, IW, and IW+2). Oxygen fugacity conditions significantly influence the compositions of partial melts. Partial melts at IW-1 are distinctly enriched in SiO2 relative to those of IW and IW+2 melts. The silica-enriched, reduced (IW-1) melts are characterized by high alkali contents and have silica-oversaturated compositions. In contrast, the silica-depleted, oxidized (≥IW) melts, which are also enriched in alkali contents, have distinctly silica-undersaturated compositions. These experimental results suggest that alkali-rich, felsic, asteroidal crusts as represented by paired achondrites Graves Nunataks 06128 and 06129 should originate from a low-degree, relatively reduced partial melt from a parent body having near-chondritic compositions. Based on recent chronological constraints and numerical considerations as well as our experimental results, we propose that such felsic magmatism should have occurred in a parent body that is smaller in size and commenced accreting later than those highly differentiated asteroids having basaltic crusts and metallic cores.

Reference
Usui T, Jones, JH, Mittlefehldt DW (2015) A partial melting study of an ordinary (H) chondrite composition with application to the unique achondrite Graves Nunataks 06128 and 06129. Meteoritics & Planetary Science (in Press)
Link to Article [doi: 10.1111/maps.12392]

Published by arrangement with John Wiley&Sons

¹K. Righter, ²L. R. Danielson, ²K. M. Pando, ³J. Williams, ³M. Humayun, ⁴R. L. Hervig, ⁴T. G. Sharp4
¹Mailcode KT, NASA Johnson Space Center, Houston, Texas, USA
²Jacobs Technology, JETS, NASA Johnson Space Center, Houston, Texas, USA
³National High Magnetic Field Laboratory and Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, Florida, USA
⁴ASU School of Earth and Space Exploration, Tempe, Arizona, USA

Highly siderophile elements (HSEs) can be used to understand accretion and core formation in differentiated bodies, due to their strong affinity for FeNi metal and sulfides. Coupling experimental studies of metal–silicate partitioning with analyses of HSE contents of Martian meteorites can thus offer important constraints on the early history of Mars. Here, we report new metal–silicate partitioning data for the PGEs and Au and Re across a wide range of pressure and temperature space, with three series designed to complement existing experimental data sets for HSE. The first series examines temperature effects for D(HSE) in two metallic liquid compositions—C-bearing and C-free. The second series examines temperature effects for D(Re) in FeO-bearing silicate melts and FeNi-rich alloys. The third series presents the first systematic study of high pressure and temperature effects for D(Au). We then combine our data with previously published partitioning data to derive predictive expressions for metal–silicate partitioning of the HSE, which are subsequently used to calculate HSE concentrations of the Martian mantle during continuous accretion of Mars. Our results show that at midmantle depths in an early magma ocean (equivalent to approximately 14 GPa, 2100 °C), the HSE contents of the silicate fraction are similar to those observed in the Martian meteorite suite. This is in concert with previous studies on moderately siderophile elements. We then consider model calculations that examine the role of melting, fractional crystallization, and sulfide saturation/undersaturation in establishing the range of HSE contents in Martian meteorites derived from melting of the postcore formation mantle. The core formation modeling indicates that the HSE contents can be established by metal–silicate equilibrium early in the history

Reference
Righter K, Danielson LR, Pando KM, Williams J, Humayun M, Hervig RL, Sharp TG (2015) Highly siderophile element (HSE) abundances in the mantle of Mars are due to core formation at high pressure and temperature. Meteoritics&Planetary Science (in Press)
Link to Article [DOI: 10.1111/maps.12393]

Published by arrangement with John Wiley&Sons