¹James M. D. Day, ¹Christopher A. Corder, ²Douglas Rumble III, ³Nelly Assayag, ³Pierre Cartigny,⁴Lawrence A. Taylor
¹Geosciences Research Division, Scripps Institution of Oceanography, La Jolla, California, USA
²Geophysical Laboratory, Carnegie Institution of Washington, Washington, District of Columbia, USA
³Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Univ. Paris Diderot, UMR 7154 CNRS, Paris, France
⁴Department of Earth and Planetary Sciences, Planetary Geosciences Institute, University of Tennessee, Knoxville, Tennessee, USA

Olivine-dominated (70–80 modal %) achondrite meteorite Lewis Cliff (LEW) 88763 originated from metamorphism and limited partial melting of a FeO-rich parent body. The meteorite experienced some alteration on Earth, evident from subchondritic Re/Os, and redistribution of rhenium within the sample. LEW 88763 is texturally similar to winonaites, has a Δ17O value of −1.19 ± 0.10‰, and low bulk-rock Mg/(Mg+Fe) (0.39), similar to the FeO-rich cumulate achondrite Northwest Africa (NWA) 6693. The similar bulk-rock major-, minor-, and trace-element abundances of LEW 88763, relative to some carbonaceous chondrites, including ratios of Pd/Os, Pt/Os, Ir/Os, and 187Os/188Os (0.1262), implies a FeO- and volatile-rich precursor composition. Lack of fractionation of the rare earth elements, but a factor of approximately two lower highly siderophile element abundances in LEW 88763, compared with chondrites, implies limited loss of Fe-Ni-S melts during metamorphism and anatexis. These results support the generation of high Fe/Mg, sulfide, and/or metal-rich partial melts from FeO-rich parent bodies during partial melting. In detail, however, LEW 88763 cannot be a parent composition to any other meteorite sample, due to highly limited silicate melt loss (0 to <<5%). As such, LEW 88763 represents the least-modified FeO-rich achondrite source composition recognized to date and is distinct from all other meteorites. LEW 88763 should be reclassified as an anomalous achondrite that experienced limited Fe,Ni-FeS melt loss. Lewis Cliff 88763, combined with a growing collection of FeO-rich meteorites, such as brachinites, brachinite-like achondrites, the Graves Nunataks (GRA) 06128/9 meteorites, NWA 6693, and Tafassasset, has important implications for understanding the initiation of planetary differentiation. Specifically, regardless of precursor compositions, partial melting and differentiation processes appear to be similar on asteroidal bodies spanning a range of initial oxidation states and volatile contents.

Reference
Day JMD, Corder CA, Rumble III D, Assayag N, Cartigny P, Taylor LA (2015) Differentiation processes in FeO-rich asteroids revealed by the achondrite Lewis Cliff 88763. Meteoritics & Planetary Science (in Press)
Link to Article [DOI: 10.1111/maps.12509]

Published by arrangement with John Wiley&Sons

^1,2Vogel, N., ³Bochsler, P., ³Bühler, F., ^4,5Heber, V. S., ³Grimberg, A., ¹Baur, H., ⁵Horstmann, M., ⁵Bischoff, A., ¹Wieler, R.
¹Institute of Geochemistry and Petrology, ETH Zürich, Zürich, Switzerland
²Department of Water Resources and Drinking Water, Eawag, Swiss Federal Institute for Aquatic Research, Dübendorf, Switzerland
³Physikalisches Institut, University of Bern, Bern, Switzerland
⁴Department of Earth, Planetary and Space Sciences, University of California Los Angeles, Los Angeles, California, USA
⁵Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Münster, Germany
⁶Division of Radiation Protection and Safety, Paul Scherrer Institut, OFLC/U103, Villigen PSI, Switzerland

We compare the solar wind (SW) He, Ne, and Ar compositions collected during the Apollo Solar Wind Composition (SWC) experiments (1969–1972; Al- & Pt-foils) and the Genesis mission (2002–2004; so-called DOS targets considered here). While published SW 20Ne/22Ne and 36Ar/38Ar ratios of both data sets agree, differences exist in the 4He/3He, 4He/20Ne, and 20Ne/36Ar ratios. However, 20Ne/36Ar ratios from Apollo-16 Pt-foils, exclusively adopted as SW values by the SWC team, are consistent with the Genesis results. We investigate if the differences indicate a variability of the SW over the course of about 30 yr, or systematic biases of the two data sets, which were collected in different environments and measured several decades apart in different laboratories (University of Bern; ETH Zurich). New measurements of Apollo-15 SWC aluminum foils in Zurich generally agree with the original measurements performed in Bern. Zurich samples show slightly lower 4He concentrations suggesting a few percent of diffusive loss of 4He during storage of the foils. A 3% difference between the He isotopic ratios measured in Bern and in Zurich possibly represents an analytical bias between the laboratories. The low SW 4He/20Ne and 20Ne/36Ar ratios in Apollo-15 Al-foils compared to Genesis data are consistent with a mixture of Genesis-like SW and noble gases from small amounts of lunar dust. Our data suggest that the mean SW He, Ne, and Ar isotopic and elemental compositions have not significantly changed between the overall Apollo and Genesis mission collection periods.

Reference
Vogel N, Bochsler P, Bühler F, Heber VS, Grimberg A, Baur H, Horstmann M, Bischoff A, Wieler R (2015) Similarities and differences between the solar wind light noble gas compositions determined on Apollo 15 SWC foils and on NASA Genesis Targets. Meteoritics & Planetary Science (in Press)
Link to Article [DOI: 10.1111/maps.12503]

Published by arrangement with John Wiley&Sons

Lidia Pittarello¹, Kitty Baert², Vinciane Debaille³ and Philippe Claeys^1
1Earth System Science, Analytical, Environmental and Geo-Chemistry (AMGC), Vrije Universiteit Brussel, Brussels, Belgium
²Materials and Chemistry, Research Group Electrochemical and Surface Engineering (SURF), Vrije Universiteit Brussel, Brussels, Belgium
³Laboratoire G-Time, Geochemistry: Tracing with isotopes, minerals and elements, Université Libre de Bruxelles, Brussels, Belgium

Classification of ordinary chondrite meteorites generally implies (1) determining the chemical group by the composition in endmembers of olivine and pyroxene, and (2) identifying the petrologic group by microstructural features. The composition of olivine and pyroxene is commonly obtained by microprobe analyses or oil immersion of mineral separates. We propose Raman spectroscopy as an alternative technique to determine the endmember content of olivine and pyroxene in ordinary chondrites, by using the link between the wavelength shift of selected characteristic peaks in the spectra of olivine and pyroxene and the Mg/Fe ratio in these phases. The existing correlation curve has been recalculated from the Raman spectrum of reference minerals of known composition and further refined for the range of chondritic compositions. Although the technique is not as accurate as the microprobe for determining the composition of olivine and pyroxene, for most of the samples the chemical group can be easily determined by Raman spectroscopy. Blind tests with ordinary chondrites of different provenance, weathering, and shock stages have confirmed the potential of the method. Therefore, we suggest that a preliminary screening and the classification of most of the equilibrated ordinary chondrites can be carried out using an optical microscope equipped with a Raman spectrometer.

Reference
Pittarello L, Baert K, Debaille V and Claeys P (2015) Screening and classification of ordinary chondrites by Raman spectroscopy. Meteoritics & Planetary Science (in Press)
Link to Article [http://onlinelibrary.wiley.com/doi/10.1111/maps.12506/abstract]
Published by arrangement with John Wiley & Sons

B.A. Wing^a,b,c, J. Farquhar^c
aDepartment of Earth and Planetary Sciences, McGill University, Montreal QC H3A 2A7 CANADA
^bGEOTOP Research Center, C.P. 8888, Succursale Centre-ville, Montréal, QC H3C 3P8, CANADA
^cEarth System Science Interdisciplinary Center and Department of Geology, University of Maryland, College Park MD 20742 USA

We present a new set of high precision measurements of relative ³³S/³²S, ³⁴S/³²S, and ³⁶S/³²S values in lunar mare basalts. The measurements are referenced to the Vienna-Canyon Diablo Troilite (V-CDT) scale, on which the international reference material, IAEA-S-1, is characterized by δ³³S = -0.061 ‰, δ³⁴S ≡ -0.3 ‰ and δ36S = -1.27 ‰. The present dataset confirms that lunar mare basalts are characterized by a remarkable degree of sulfur isotopic homogeneity, with most new and published SF6-based sulfur isotope measurements consistent with a single mass-dependent mean isotopic composition of δ³⁴S = 0.58 ± 0.05 ‰, Δ³³S = 0.008 ± 0.006 ‰, and Δ³⁶S = 0.2 ± 0.2 ‰, relative to V-CDT, where the uncertainties are quoted as 99% confidence intervals on the mean. This homogeneity allows identification of a single sample (12022, 281) with an apparent ³³S enrichment, possibly reflecting cosmic-ray-induced spallation reactions. It also reveals that some mare basalts have slightly lower δ³⁴S values than the population mean, which is consistent with sulfur loss from a reduced basaltic melt prior to eruption at the lunar surface. Both the sulfur isotope homogeneity of the lunar mare basalts and the predicted sensitivity of sulfur isotopes to vaporization-driven fractionation suggest that less than ≈1-10% of lunar sulfur was lost after a potential moon-forming impact event.

Reference
Wing BA, Farquhar J (2015) Sulfur isotope homogeneity of lunar mare basalts. Geochimica et Cosmochimica Acta (in Press)
Link to Article [ http://www.sciencedirect.com/science/article/pii/S0016703715005323]
Copyright Elsevier

J.C. Aponte^1,2, J.P. Dworkin¹ and J.E. Elsila^1
1Solar System Exploration Division, Code 691, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
²Department of Chemistry, Catholic University of America, Washington, District of Columbia, USA

The CI1 Orgueil meteorite is a highly aqueously altered carbonaceous chondrite. It has been extensively studied, and despite its extensive degree of aqueous alteration and some documented instances of contamination, several indigenous organic compounds including amino acids, carboxylic acids, and nucleobases have been detected in its carbon-rich matrix. We recently developed a novel gas chromatographic method for the enantiomeric and compound-specific isotopic analyses of meteoritic aliphatic monoamines in extracts and have now applied this method to investigate the monoamine content in Orgueil. We detected 12 amines in Orgueil, with concentrations ranging from 1.1 to 332 nmol g^-1 of meteorite and compared this amine content in Orgueil with that of the CM2 Murchison meteorite, which experienced less parent-body aqueous alteration. Methylamine is four times more abundant in Orgueil than in Murchison. As with other species, the amine content in Orgueil extracts shows less structural diversity than that in Murchison extracts. We measured the compound-specific stable carbon isotopic ratios (δ¹³C) for 5 of the 12 monoamines detected in Orgueil and found a range of δ¹³C values from –20 to +59‰. These δ¹³C values fall into the range of other meteoritic organic compounds, although they are ¹³C-depleted relative to their counterparts extracted from the Murchison meteorite. In addition, we measured the enantiomeric composition for the chiral monoamines (R)- and (S)-sec-butylamine in Orgueil, and found it was racemic within experimental error, in contrast with the l-enantiomeric excess found for its amino acid structural analog isovaline. The racemic nature of sec-butylamine in Orgueil was comparable to that previously observed in Murchison, and to other CM2 and CR2 carbonaceous chondrites measured in this work (ALH 83100 [CM1/2], LON 94101 [CM2], LEW 90500 [CM2], LAP 02342 [CR2], and GRA 95229 [CR2]). These results allow us to place some constraints on the effects of aqueous alteration observed over the monoamine concentrations in Orgueil and Murchison, and to evaluate the primordial synthetic relationships between meteoritic monoamines and amino acids.

Reference
Aconite JC, Dworkin JP and Elsila JE (2015) Indigenous aliphatic amines in the aqueously altered Orgueil meteorite. Meteoritics & Planetary Science (in Press)
Link to Article [http://onlinelibrary.wiley.com/doi/10.1111/maps.12507/abstract]
Published by arrangement with John Wiley & Sons

M. E. Sanborn^a, R. W. Carlson^b, M. Wadhwa^a
aCenter for Meteorite Studies, School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ, 85287-1404, USA
^bDepartment of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Rd. NW, Washington, DC 20015-1305, USA

Angrites are a group of basaltic achondrites with distinctive mineralogic and geochemical characteristics that have the potential to provide insights into processes occurring on planetesimals in the early Solar System. These achondrites have been used as anchors linking the relative age information obtained from short-lived, extinct chronometers (e.g., Al-Mg, Hf-W, and Mn-Cr) with absolute chronometers (e.g., U-Pb). Angrites provide excellent examples of early differentiation processes, such as core formation and silicate differentiation, on protoplanetary bodies. The significant increase in the number of known angrite samples in recent years has offered the opportunity to compare several short- and long-lived isotopic systems in samples with different petrogenetic histories that formed on the same parent body. To this end, the ¹⁴⁷Sm-¹⁴³Nd, ¹⁴⁶Sm-¹⁴²Nd, ¹⁷⁶Lu-¹⁷⁶Hf, and ⁸⁷Rb-⁸⁶Sr isotope systematics have been investigated in a suite of plutonic, coarse-grained (NWA 4590, NWA 4801, and NWA 2999) and quenched, fine-grained (D’Orbigny) angrites. The coupled ¹⁴⁷,¹⁴⁶Sm-¹⁴³,¹⁴²Nd systematics indicate possible isotopic disturbances in two angrites (D’Orbigny and NWA 2999) resulting from post-crystallization processes. The internal ¹⁴⁶Sm-¹⁴²Nd isochrons of two coarse-grained angrites (NWA 4590 and NWA 4801) provide an updated best estimate of the initial Solar System ¹⁴⁶Sm/¹⁴⁴Sm ratio (i.e., at 4568 Ma) of 0.0084±0.0003. The ¹⁷⁶Lu-¹⁷⁶Hf isotope systematics in these angrites do not provide evidence of a previously proposed intense irradiation event in the early Solar System. The internal ¹⁷⁶Lu-¹⁷⁶Hf isochrons for the NWA 4590 and D’Orbigny angrites provide an estimate for the Solar System initial ¹⁷⁶Hf/¹⁷⁷Hf ratio of 0.279775±0.000031 (2σ) that agrees within uncertainty with the value of average chondrites reported by Bouvier et al. (2008). Finally, the calculated initial 87Sr/86Sr ratios based on the measured Sr-isotopic composition of plagioclase in these angrites yield an estimated initial ⁸⁷Sr/⁸⁶Sr ratio of 0.698980±0.000011 for the angrite parent body. This is indistinguishable from a recently determined value for the Solar System initial ⁸⁷Sr/⁸⁶Sr based on values measured in calcium-aluminum-rich inclusions (CAIs) after correcting for nucleosynthetic effects in the CAIs. The low initial ⁸⁷Sr/⁸⁶Sr of the angrite parent body implies that it acquired its volatile element depleted characteristic within 1.8 Ma of Solar System formation, likely because it accreted from volatile depleted planetesimals that formed in the hot inner nebula. These integrated isotopic systematics suggest a complex history for the angrite parent body not previously inferred from short-lived chronometers and provide new estimates for the initial isotopic composition of the early Solar System.

Reference
Brown SM, Grove TL (2015) ^147,146Sm-^143,142Nd, ¹⁷⁶Lu-¹⁷⁶Hf, and ⁸⁷Rb-⁸⁷Sr Systematics in the Angrites: Implications for Chronology and Processes on the Angrite Parent Body. Geochimica et Cosmochimica Acta (in Press)
Link to Article [ http://www.sciencedirect.com/science/article/pii/S001670371500530X]
Copyright Elsevier

V. Al-Lagoa, M. Delbó, and G. Libourel
Laboratoire Lagrange, UMR7293, University de la Cote d’Azur, CNRS, Observatoire de la Cote d’Azur, F-06304 Nice Cedex 4, France

The so-called “early activity” of comet 67P/Churyumov?Gerasimenko has been observed to originate mostly in parts of the concave region or “neck” between its two lobes. Since activity is driven by the sublimation of volatiles, this is a puzzling result because this area is less exposed to the Sun and is therefore expected to be cooler on average. We used a thermophysical model that takes into account thermal inertia, global self-heating, and shadowing, to compute surface temperatures of the comet. We found that, for every rotation in the 2014 August?December period, some parts of the neck region undergo the fastest temperature variations of the comet’s surface precisely because they are shadowed by their surrounding terrains. Our work suggests that these fast temperature changes are correlated to the early activity of the comet, and we put forward the hypothesis that erosion related to thermal cracking is operating at a high rate on the neck region due to these rapid temperature variations. This may explain why the neck contains some ice?as opposed to most other parts of the surface?and why it is the main source of the comet’s early activity. In a broader context, these results indicate that thermal cracking can operate faster on atmosphereless bodies with significant concavities than implied by currently available estimates.

Reference
Al-Lagoa V, Delbó M and Libourel G (2015) Rapid temperature changes and the early activity on comet 67P/Churumov-Gerasimenko. Astrophysical Journal 810 L22 (in Press)
Link to Article [ http://iopscience.iop.org/article/10.1088/2041-8205/810/2/L22]

M. Viikinkoski¹ et al. (>10)
¹Department of Mathematics, Tampere University of Technology, PO Box 553, 33101 Tampere, Finland

We use the recently released Atacama Large Millimeter Array (ALMA) and VLT/SPHERE science verification data, together with earlier adaptive-optics images, stellar occultation, and lightcurve data to model the 3D shape and spin of the large asteroid (3) Juno with the all-data asteroid modelling (ADAM) procedure. These data set limits on the plausible range of shape models, yielding reconstructions suggesting that, despite its large size, Juno has sizable unrounded features moulded by non-gravitational processes such as impacts.

Reference
Viikinkoski et al. (2015) VLT/SPHERE- and ALMA-based shape reconstruction of asteroid (3) Juno. Astronomy & Astrophysics 581, L3 (in Press)
Link to Article [ http://www.aanda.org/articles/aa/abs/2015/09/aa26626-15/aa26626-15.html]

T. Brachaniec, K. Szopa and Ł. Karwowski
Department of Geochemistry, Mineralogy and Petrology, Faculty of Earth Sciences, University of Silesia, Sosnowiec, Poland

Moldavites represent tektites derived from the Ries impact structure (~24 km diameter, ~15 Myr old) in southern Germany. Two new localities with parautochthonous moldavites in southwestern Poland were found. In these localities, fluvial sediments of the so-called Gozdnicka formation host the moldavites. Characteristic tektite features, especially bubbles and inclusions of lechatelierite, are reported. The moldavites’ size distribution and their abraded shapes indicate that they were redeposited from the nearby Lusatia substrewn field.

Reference
Brachaniec T, Szopa K and Karwowski Ł (2015) Two new discovery of parautochthonous moldavites in southwestern Poland, Central Europe. Meteoritics & Planetary Science (in Press)
Link to Article [ http://onlinelibrary.wiley.com/doi/10.1111/maps.12504/abstract]
Published by arrangement with John Wiley & Sons

S.M. Brown , T.L. Grove
Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139

We examine the fO₂-dependent melting conditions of the Apollo 14 yellow intermediate-Ti ultramafic glasses and the melting processes that formed the full suite of lunar yellow ultramafic glasses. Multiple saturation experiments indicate that the Apollo 14 yellow glass would have been in equilibrium with residual olivine and low-Ca pyroxene near 1530°C and 2.4 GPa at ΔIW = +2. At ΔIW = -2, the multiple saturation point moves to greater depth and higher temperature to 1580°C and 3.0 GPa. Combining the results of this study with that of [26] on more Ti-rich Apollo orange and red glass indicates that the fO2-induced change in multiple saturation pressure correlates with the Fe-Ti# (molar (FeO + TiO₂*)/(MgO + FeO + TiO₂*), where TiO₂* = all Ti calculated as Ti⁴⁺) of the liquid. Further, a decrease in the olivine Fe-Mg exchange coefficient at lower fO2 suggests that Fe²⁺ is complexing more efficiently with Ti³⁺ at the expense of Mg in the melt than it did with Ti⁴⁺ at higher fO₂.

Reference
Brown SM, Grove TL (2015) Origin of the Apollo 14, 15, and 17 yellow ultramafic glasses by mixing of deep cumulate remelts. Geochimica et Cosmochimica Acta (in Press)
Link to Article [ http://www.sciencedirect.com/science/article/pii/S0016703715005293]
Copyright Elsevier