^1,2Libourel, G.,³Nakamura, A.M.,⁴Beck, P.,⁴Potin, S.,⁵Ganino, C.,⁶Jacomet, S.,³Ogawa, R.,⁷Hasegawa, S.,¹Michel, P.
Science Advances 5, eaav3971 Link to Article [DOI: 10.1126/sciadv.aav3971]
¹Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Boulevard de l’Observatoire, CS 34229, Nice Cedex 4, 06304, France
²Hawai‘i Institute of Geophysics and Planetology, School of Ocean, Earth Science and Technology, University of Hawai‘i at Mānoa, Honolulu, HI 96821, United States
³Graduate School of Science, Kobe University, 1-1 Rokkoudai-cho, Nada-ku, Kobe, 657-8501, Japan
⁴UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041, France
⁵Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Géoazur, 250 rue Albert Einstein, Sophia-Antipolis, Valbonne, 06560, France
⁶MINES Paristech, PSL-Research University, CEMEF-Centre de Mise en Forme des Matériaux, Centre for Material Forming, CNRS UMR 7635, CS 10207, 1 rue Claude Daunesse, Sophia-Antipolis Cedex, 06904, France
⁷Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, 252-5210, Japan

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^1,2Creech, J.B.,^1,3Moynier, F.,^4,5Koeberl, C.
Chemical Geology 528, 119279 Link to Article [DOI: 10.1016/j.chemgeo.2019.119279]
¹Institut de Physique du Globe de Paris, Université de Paris, 1 Rue Jussieu, Paris cedex 05, 75328, France
²Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia
³Institut Universitaire de France, Paris, 75005, France
⁴Department of Lithospheric Research, University of Vienna, Althanstrasse 14, Vienna, 1090, Austria
⁵Natural History Museum, Burgring 7, Vienna, 1010, Austria

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^1,2M. E. I. RIEBE,¹H. BUSEMANN,²C. M. O’D. ALEXANDER,²L. R. NITTLER,³C. D. K. HERD,¹C. MADEN,²J. WANG,¹R. WIELER
Meteoritics & Planetary Science (in Press) Link to Article [doi: 10.1111/maps.13383]
¹Institute of Geochemistry and Petrology, ETH Zurich, CH-8092, Zurich, Switzerland
²DTM, Carnegie Institution of Washington, 5241 Broad Branch Road, Washington, District of Columbia 20015, USA
³Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
Published by arrangement with John Wiley & Sons

Effects of aqueous alteration on primordial noble gas carriers were investigated by analyzing noble gases and determining presolar SiC abundances in insoluble organic matter (IOM) from four Tagish Lake meteorite (C2-ung.) samples that experienced different degrees of aqueous alteration. The samples contained a mixture of primordial noble gases from phase Q and presolar nanodiamonds (HL, P3), SiC (Ne-E[H]), and graphite (Ne-E[L]). The second most altered sample (11i) had a ~2–3 times higher Ne-E concentration than the other samples. The presolar SiC abundances in the samples were determined from NanoSIMS ion images and 11i had a SiC abundance twice that of the other samples. The heterogeneous distribution of SiC grains could be inherited from heterogeneous accretion or parent body alteration could have redistributed SiC grains. Closed system step etching (CSSE) was used to study noble gases in HNO3-susceptible phases in the most and least altered samples. All Ne-E carried by presolar SiC grains in the most altered sample was released during CSSE, while only a fraction of the Ne-E was released from the least altered sample. This increased susceptibility to HNO3 likely represents a step toward degassing. Presolar graphite appears to have been partially degassed during aqueous alteration. Differences in the 4He/36Ar and 20Ne/36Ar ratios in gases released during CSSE could be due to gas release from presolar nanodiamonds, with more He and Ne being released in the more aqueously altered sample. Aqueous alteration changes the properties of presolar grains so that they react similar to phase Q in the laboratory, thereby altering the perceived composition of Q.

¹A. GARENNE,^1,2P. BECK,³G. MONTES-HERNANDEZ,¹L. BONAL,¹E. QUIRICO,⁴O. PROUX,⁵J.L. HAZEMANN
Meteoritics & Planetary Science (In Press) Link to Article [doi: 10.1111/maps.13377]
¹CNRS, IPAG, Universite Grenoble Alpes, F-38000 Grenoble, France ²Institut Universitaire de France, Paris, France
³Institut des Sciences de la Terre (IsTERRE), Universite Grenoble Alpes/CNRS-INSU, Grenoble, France
⁴Observatoire des Sciences de l’Univers de Grenoble (OSUG) CNRS UMS 832, 414 rue de la piscine, 38400 Saint Martin d’Heres, France
⁵CNRS, Institut Neel, Universite Grenoble Alpes, 25 av. des Martyrs, 38042 Grenoble, France
Published by arrangement with John Wiley & Sons

The valence of iron has been used in terrestrial studies to trace the hydrolysis of primary silicate rocks. Here, we use a similar approach to characterize the secondary processes, namely thermal metamorphism and aqueous alteration, that have affected carbonaceous chondrites. X-ray absorption near-edge structure spectroscopy at the Fe-Kedge was performed on a series of 36 CM, 9 CR, 10 CV, and 2 CI chondrites. While previous studies have focused on the relative distribution of Fe0 with respect to oxidized iron (Feox = Fe2+ + Fe3+) or the iron distribution in some specific phases (e.g., Urey–Craig diagram; Urey and Craig 1953), our measurements enable us to assess the fractions of iron in each of its three oxidation states: Fe0, Fe2+, and Fe3+. Among the four carbonaceous chondrites groups studied, a correlation between the iron oxidation index (IOI = [2 (Fe2+) + 3(Fe3+)]/[FeTOT]) and the hydrogen content is observed. However, within the CM group, for which a progressive alteration sequence has been defined, a conversion of Fe3+ to Fe2+ is observed with increasing degree of aqueous alteration. This reduction of iron can be explained by an evolution in the mineralogy of the secondary phases. In the case of the few CM chondrites that experienced some thermal metamorphism, in addition to aqueous alteration, a redox memory of the aqueous alteration is present: a significant fraction of Fe3+ is present, together with Fe2+ and sometimes Fe0. From our data set, the CR chondrites show a wider range of IOI from 1.5 to 2.5. In all considered CR chondrites, the three oxidation states of iron coexist. Even in the least-altered CR chondrites, the fraction of Fe3+ can be high (30% for MET 00426). This observation confirms that oxidized iron has been integrated during formation of fine-grained amorphous material in the matrix (Le Guillou and Brearley 2014; Le Guillou et al. 2015; Hopp and Vollmer 2018). Last, the IOI of CV chondrites does not reflect the reduced/oxidized classification based on metal and magnetite proportions, but is strongly correlated with petrographic types. The valence of iron in CV chondrites therefore appears to be most closely related to thermal history, rather than aqueous alteration, even if these processes can occur together (Krot et al. 2004; Brearley and Krot 2013).

^1,2Celia Dalou,²Marc M.Hirschmann,³Steven D.Jacobsen,⁴CharlesLe Losq
Geochimica et Cosmochimcia Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2019.08.029]
¹Centre de Recherches Pétrographiques et Géochimiques, 15 rue Notre-Dame des Pauvres, BP20, 54501 Vandoeuvre-lès-Nancy Cedex, France
²Dept. of Earth Sciences, 108 Pillsbury Hall, University of Minnesota, Minneapolis, MN 55455, USA
³Department of Earth and Planetary Sciences, Northwestern University, Evanston, IL 60208, United States
⁴Research School of Earth Sciences, The Australian National University, Building 142, Mills Road, Canberra, ACT 2601, Australia
Copyright Elsevier

To better understand the solution of volatile species in a reduced magma ocean, we identify via Raman spectroscopy the nature of C-O-H-N volatile species dissolved in a series of reduced basaltic glasses. The oxygen fugacity (ƒ_O2) during synthesis varied from highly reduced at two log units below the iron-wustite buffer (IW-2.1) to moderately reduced (IW-0.4), spanning much of the magmatic ƒ_O2 conditions during late stages of terrestrial accretion. Raman vibrational modes for H₂, NH₂^–, NH₃, CH₄, CO, CN^–, N₂, and OH^– species are inferred from band assignments in all reduced glasses. The integrated area of Raman bands assigned to N₂, CH₄, NH₃ and H₂ vibrations in glasses increases with increasing molar volume of the melt, whereas that of CO decreases. Additionally, with increasing ƒ_O2, CO band areas increase while those of N₂ decrease, suggesting that the solubility of these neutral molecules is not solely determined by the melt molar volume under reduced conditions. Coexisting with these neutral molecules, other species as CN^–, NH₂^– and OH^– are chemically bonded within the silicate network. The observations indicate that, under reduced conditions, 1) H₂, NH₂^–, NH₃, CH₄, CO, CN^–, N₂, and OH^– species coexist in silicate glasses representative of silicate liquids in a magma ocean 2) their relative abundances dissolved in a magma ocean depend on melt composition, ƒ_O2 and the availability of H and, 3) metal-silicate partitioning or degassing reactions of those magmatic volatile species must involve changes in melt and vapor speciation, which in turn may influence isotopic fractionation.

^1,2Timothy T. BARROWS,³John MAGEE,⁴Gifford MILLER,⁵L. Keith FIFIELD
Meteoritics & Planetary Society (in Press) Link to Article [doi: 10.1111/maps.13378]
¹School of Earth and Environmental Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia
²Department of Geography, University of Portsmouth, Portsmouth PO1 2UP, UK
³Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory 0200, Australia
⁴INSTAAR and Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309, USA
⁵Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University, Canberra,Australian Capital Territory 2601, Australia
Published by arrangement with John Wiley & Sons

Wolfe Creek crater lies in northwestern Australia at the edge of the Great SandyDesert. Together with Meteor Crater, it is one of the two largest craters on Earth fromwhich meteorite fragments have been recovered. The age of the impact is poorly constrainedand unpublished data places the event at about 300,000 years ago. In comparison, MeteorCrater is well constrained by exposure dating. In this paper, we present new ages for WolfeCreek Crater from exposure dating using the cosmogenic nuclides10Be and26Al, togetherwith optically stimulated luminescence ages (OSL) on sand from a site created by theimpact. We also present a new topographic survey of the crater using photogrammetry. Theexposure ages range from~86 to 128 ka. The OSL ages indicate that the age of the impactis most likely to be~120 ka with a maximum age of 137 ka. Considering the geomorphicsetting, the most likely age of the crater is 1209 ka. Last, we review the age of MeteorCrater in Arizona. Changes in production rates and scaling factors since the original datingwork revise the impact age to 61.14.8 ka, or~20% older than previously reported.

¹Haruka ONO,^2,3Atsushi TAKENOUCHI,⁴Takashi MIKOUCHI,³Akira YAMAGUCHI
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13384]
¹Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
²Department of Basic Science, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
³National Institute of Polar Research (NIPR), 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan
⁴The University Museum, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Published by arrangement with John Wiley & Sons

Some eucrites contain up to 10 vol% silica minerals; however, silica minerals havenot been studied in detail so far. We performed a mineralogical study of silica minerals inthree cumulate eucrites (Moore County, Moama, and Yamato [Y] 980433). Monoclinictridymite was common in all three samples. Moama contained orthorhombic tridymite aslamellae within monoclinic tridymite grains. Y 980433 included quartz around an impactmelt vein. The presence of orthorhombic tridymite in Moama indicates that Moama cooledmore rapidly than the other two samples at low temperatures (<400°C). This result isdifferent from the slower cooling rates of Moama (≳0.0004°Cyr1) than that of MooreCounty (>0.3°Cyr1, after the shock event) at high temperatures (>500°C) estimated fromcompositional profiles of pyroxene exsolution lamellae. The difference of the cooling ratesmay reflect their geological settings. Y 980433 cooled slowly at low temperature, as didMoore County. Quartz in Y 980433 could be a local product transformed from monoclinictridymite by a shock event. We suggest that silica minerals in meteorites record thermalhistories at low temperatures and shock events.

¹Robert J. MACKE,²Cyril OPEIL,¹Guy J. CONSOLMAGNO
Meteoritics & Planetary Society (in Press) Link to Article [https://doi.org/10.1111/maps.13385]
Vatican Observatory, V-00120 Vatican City-State2Department of Physics, Boston College, Chestnut Hill, Massachusetts 02215, USA
Published by arrangement with John Wiley & Sons

Low-temperature specific heat capacities of meteorites provide valuable data forunderstanding the composition and evolution of meteorites and modeling the thermalbehavior of their source asteroids. By liquid nitrogen immersion, we measured average low-temperature heat capacities for 60 ordinary chondrite falls from the Vatican collection. Wefurther characterized the temperature dependence of ordinary chondrite by directmeasurement of Cp(T) over the range 5–320 K for five OC falls, coupled by composition-based models for 94 ordinary chondrites. We find that the heat capacity as a function oftemperature for typical ordinary chondrites can be closely approximated by a third-orderpolynomial in temperature. Furthermore, those polynomial coefficients can be estimatedfrom the single-value average heat capacity measurement. These measurements haveimportant implications for the orbital and spin evolution of S- and Q-type asteroids via thevarious Yarkovsky effects and the thermal evolution of meteorite parent bodies.

^1,3Andreas T. Hertwig,²Makoto Kimura,¹Céline Defouilloy,¹Noriko T. Kita
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13379]
¹WiscSIMS, Department of Geoscience, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA 2
²National Institute of Polar Research, Meteorite Research Center, Midoricho 10-3, Tachikawa Tokyo 190-8518, Japan 3
³Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles,
Los Angeles, California 90095, USA
Published by arrangement with John Wiley & Sons

We performed in situ oxygen three-isotope measurements of chondrule olivine,pyroxenes, and plagioclase from the newly described CVRedchondrite NWA 8613.Additionally, oxygen isotope ratios of plagioclase in chondrules from the Kaba CV3OxBchondrite were determined to enable comparisons of isotope ratios and degree of alterationof chondrules in both CV lithologies. NWA 8613 was affected by only mild thermalmetamorphism. The majority of oxygen isotope ratios of olivine and pyroxenes plot along aslope-1 line in the oxygen three-isotope diagram, except for a type II and a remolten barredolivine chondrule. When isotopic relict olivine is excluded, olivine, and low- and high-Capyroxenes are indistinguishable regardingD17O values. Conversely, plagioclase in chondrulesfrom NWA 8613 and Kaba plot along mass-dependent fractionation lines. Oxygen isotopicdisequilibrium between phenocrysts and plagioclase was caused probably by exchange ofplagioclase with16O-poor fluids on the CV parent body. Based on an existing oxygenisotope mass balance model, possible dust enrichment and ice enhancement factors wereestimated. Type I chondrules from NWA 8613 possibly formed at moderately high dustenrichment factors (509to 1509CI dust relative to solar abundances); estimates for waterice in the chondrule precursors range from 0.29to 0.69the nominal amount of ice in dustof CI composition. Findings agree with results from an earlier study on oxygen isotopes inchondrules of the Kaba CV chondrite, providing further evidence for a relatively dry andonly moderately high dust-enriched disk in the CV chondrule-forming region.

^1,2,3S. N. Valencia,¹B. L. Jolliff,¹R. L. Korotev
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13370]
¹Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri 63130, USA
²Current address: Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA
¹NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
Published by arrangement with John Wiley & Sons

The Northwest Africa (NWA) 773 clan of lunar meteorite stones are coarse‐grained breccias that provide an opportunity to examine a lunar igneous system that includes inferred intrusive and extrusive lithologies, possibly related through a common liquid line of descent from a single source region. Such extensive sampling of a single very low‐Ti (VLT) magmatic system on the Moon is unprecedented among the lunar samples. This study focuses on the olivine gabbro (OG), anorthositic gabbro (AG), and ferroan gabbro (FG) lithologies variably contained in NWA 773, NWA 2727, NWA 3160, NWA 3170, NWA 7007, and NWA 10656. Mineral compositions in the three gabbros indicate the crystallization sequence OG → AG → FG. Petrologic modeling of these three lithologies, and an olivine phyric basalt that also occurs in the NWA 773 clan, however, suggests that the relationship among the lithologies is more complex. The OG and basalt can be modeled as originating from a VLT KREEP‐bearing parental melt similar to the Apollo 14 Green Glass b1 composition through mainly equilibrium crystallization. The AG and FG, however, do not fit this simple model and require either a more complex crystallization sequence involving fractional crystallization, magma chamber recharge, or perhaps heterogeneity in the source region.