¹Richard J. Walker
¹Isotope Geochemistry Laboratory, Department of Geology, University of Maryland, College Park, MD 20742, USA

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Reference
Walker RJ (2014)Siderophile element constraints on the origin of the Moon. Philosophical Transactions of the Royal Society A 13, 372, 2024
Link to Article [doi: 10.1098/rsta.2013.0258]

¹G. Avice, ¹B Marty
¹ CRPG-CNRS, Université de Lorraine, 15 rue Notre-Dame des Pauvres, BP 20, 54501 Vandoeuvre-lès-Nancy Cedex, France

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Reference
Avice G, Marty B (2014) The iodine–plutonium–xenon age of the Moon–Earth system revisited. Philosophical Transactions of the Royal Society, A 13, 2024
Link to Article [doi: 10.1098/rsta.2013.0260]

¹Richard W. Carlson, ²Lars E. Borg, ²Amy M. Gaffney, ³Maud Boyet
¹Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington DC 20015, USA
²Chemical Sciences Division, Lawrence Livermore National Laboratory, 7000 East Avenue L-231, Livermore, CA 94550, USA
³Laboratoire Magmas et Volcans, Universite Blaise Pascal, CNRS UMR 6524, 5 Rue Kessler, Clermont-Ferrand 63038, France

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Reference
Carlson RW, Borg LE, Gaffney AM, Boyet M (2014) Rb-Sr, Sm-Nd and Lu-Hf isotope systematics of the lunar Mg-suite: the age of the lunar crust and its relation to the time of Moon formation. Philosophical Transactions of the Royal Society
A 13, 372, 2024
Link to Article [doi: 10.1098/rsta.2013.0246]

¹James M. D. Day, ² Frederic Moynier

¹Scripps Isotope Geochemistry Laboratory, Geosciences Research Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0244, USA
²Institut de Physique du Globe de Paris, Université Paris Diderot, Sorbonne Paris Cité, 1 rue Jussieu, 75005 Paris, France

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Reference
Day JMD, Moynier F (2014) Evaporative fractionation of volatile stable isotopes and their bearing on the origin of the Moon. Philosophical Transactions of the Royal Society A 13,372,2024
Link to Article [doi: 10.1098/rsta.2013.0259]

¹Ryan Anderson et al. (>10)*
¹U.S. Geological Survey Astrogeology Science Center, 2255 N. Gemini Dr., Flagstaff, AZ 86001, USA. 1-734-657-8085
*Find the extensive, full author and affiliation list on the publishers Website

The ChemCam campaign at the fluvial sedimentary outcrop “Shaler” resulted in observations of 28 non-soil targets, 26 of which included active laser induced breakdown spectroscopy (LIBS), and all of which included remote micro imager (RMI) images. The Shaler outcrop can be divided into seven facies based on grain size, texture, color, resistance to erosion, and sedimentary structures. The ChemCam observations cover Facies 3 through 7. For all targets, the majority of the grains were below the limit of the RMI resolution, but many targets had a portion of resolvable grains coarser than ∼0.5 mm. The Shaler facies show significant scatter in LIBS spectra and compositions from point to point, but several key compositional trends are apparent, most notably in the average K2O content of the observed facies. Facies 3 is lower in K2O than the other facies and is similar in composition to the “snake,” a clastic dike that occurs lower in the Yellowknife Bay stratigraphic section. Facies 7 is enriched in K2O relative to the other facies and shows some compositional and textural similarities to float rocks near Yellowknife Bay. The remaining facies (4, 5, and 6) are similar in composition to the Sheepbed and Gillespie Lake members, although the Shaler facies have slightly elevated K2O and FeOT. Several analysis points within Shaler suggest the presence of feldspars, though these points have excess FeOT which suggests the presence of Fe oxide cement or inclusions. The majority of LIBS analyses have compositions which indicate that they are mixtures of pyroxene and feldspar. The Shaler feldspathic compositions are more alkaline than typical feldspars from shergottites, suggesting an alkaline basaltic source region, particularly for the K2O-enriched Facies 7. Apart from possible iron-oxide cement, there is little evidence for chemical alteration at Shaler, although calcium-sulfate veins comparable to those observed lower in the stratigraphic section are present. The differing compositions, and inferred provenances at Shaler, suggest compositionally heterogeneous terrain in the Gale crater rim and surroundings, and intermittent periods of deposition.

Reference
Anderson R et al. (2014) ChemCam Results from the Shaler Outcrop in Gale Crater, Mars. Icarus (in Press)
Link to Article [DOI: 10.1016/j.icarus.2014.07.025]

Copyright Elsevier

¹B. Laurent, ¹M. Roskosz, ²L. Remusat, ¹H. Leroux, ³H. Vezin, ¹C. Depecker

¹Unité Matériaux et Transformations, CNRS UMR 8207 – Université Lille 1, 59655 Villeneuve d’Ascq, France
²Laboratoirede Minéralogie et Cosmochimie du Muséum, UMR CNRS 7202, MNHN, CP 52, 57 rue Cuvier, 75231 Paris Cedex 05, France
³Laboratoire de Spectrochimie Infrarouge et Raman, UMR 8516, 59655 Villeneuve d’Ascq, France

The effects of electron irradiation on the structure and the D/H signature of a synthetic analogue of extraterrestrial insoluble organic matter (IOM) were studied. Polyethylene terephthalate (PET) was chosen because it contains both aliphatic and aromatic functional groups. A 900 nm-thick film was irradiated with electrons within the energy range 4 – 300 keV, for different run durations. Temperature influence was also tested. Irradiated residues were structurally and isotopically characterized by infrared spectroscopy (IR), electronic paramagnetic resonance (EPR), and Secondary Ion Mass Spectrometry (SIMS). Over energy deposition, spectroscopic results indicate (i) a gradual amorphization with chain scissions, (ii) an increase of CH2/CH3 and (iii) the formation of quinones. The EPR study shows that mono- and biradicals (organic species with one or several unpaired valence electrons) are also formed during irradiation. As these structural modifications occur, the δD (initially at –33‰ relative to SMOW) decreases first during a transient step and then stabilizes at ∼ +300‰. There is a strong correlation between the changes recorded by the different methods and the electron dose. Deposited energy appears to be the key parameter to induce these modifications. In this respect a low-energy electron irradiation causes more damages than high energy ones. Based on our data and considering the current solar electron flux, the irradiation at moderate energy (1-10 keV) can produce significant D-enrichments of the IOM in a timescale compatible with the evolution of a typical protoplanetary disk.

Reference
Laurent B, Roskosz M, Remusta L, Leroux H, Vezin H, Depecker C (2014) Isotopic and structural signature of experimentally irradiated organic matter. Geochimica et Cosmochimica Acta (in Press)
link to Article [DOI: 10.1016/j.gca.2014.07.023]

Copyright Elsevier

¹G. Jeffrey Taylor ²Mark A. Wieczorek
¹Hawai’i Institute of Geophysics and Planetology, University of Hawai’i, Honolulu, HI 96822, USA
²Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, Case 7071, Lamarck A, 35 rue Hélène Brion, Paris Cedex 13 75205, France

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Reference
Taylor GJ, Wieczoreck MA (2014) Lunar bulk chemical composition: a post-Gravity Recovery and Interior Laboratory reassessment. Philosophical Transactions of the Royal Society A 13, 372, 2024
Link to Article [doi: 10.1098/rsta.2013.0242]

¹Nicolas Dauphas, ¹Christoph Burkhardt, ²Paul H. Warren, ³Teng Fang-Zhen
¹Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA
²Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, USA
³Isotope Laboratory, Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA

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Reference
Dauphas N, Burkhardt C, Warren PH, Fang-Zhen T (2014) Geochemical arguments for an Earth-like Moon-forming impactor. Philosophical Transactions of the Royal Society A13, 372, 2024
Link to Article [doi:10.1098/rsta.2013.0244]

¹Takayuki Ishii et al. (>10)*
¹Department of Chemistry, Gakushuin University, Mejiro, Toshima-ku, Tokyo 171-8588, Japan
*Find the extensive, full author and affiliation list on the publishers website

We determined phase relations in FeCr2O4 at 12–28 GPa and 800–1600 °C using a multi-anvil apparatus. At 12–16 GPa, FeCr2O4 spinel (chromite) first dissociates into two phases: a new Fe2Cr2O5 phase + Cr2O3 with the corundum structure. At 17–18 GPa, the two phases combine into CaFe2O4-type and CaTi2O4-type FeCr2O4 below and above 1300 °C, respectively. Structure refinements using synchrotron X-ray powder diffraction data confirmed the CaTi2O4-structured FeCr2O4 (Cmcm), and indicated that the Fe2Cr2O5 phase is isostructural to a modified ludwigite-type Mg2Al2O5 (Pbam). In situ high-pressure high-temperature X-ray diffraction experiments showed that CaFe2O4-type FeCr2O4 is unquenchable and is converted into another FeCr2O4 phase on decompression. Structural analysis based on synchrotron X-ray powder diffraction data with transmission electron microscopic observation clarified that the recovered FeCr2O4 phase has a new structure related to CaFe2O4-type. The high-pressure phase relations in FeCr2O4 reveal that natural FeCr2O4-rich phases of CaFe2O4- and CaTi2O4-type structures found in the shocked Suizhou meteorite were formed above about 18 GPa at temperature below and above 1300 °C, respectively. The phase relations also suggest that the natural chromitites in the Luobusa ophiolite previously interpreted as formed in the deep-mantle were formed at pressure below 12–16 GPa.

Reference
Takayuki T et al. (2014) High-pressure phase transitions in FeCr2O4 and structure analysis of new post-spinel FeCr2O4 and Fe2Cr2O5 phases with meteoritical and petrological implications. American Mineralogist 99, 1788-1797
Link to Article [doi:10.2138/am.2014.4736]

Copyright: The Mineralogical Society of America

¹Patricia L. Clay, ²Brian O’Driscoll, ³Brian G.J. Upton, ¹Henner Busemann
¹School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, U.K.
²School of Physical and Geographical Sciences, Keele University, Keele ST5 5BG, U.K.
³School of Geosciences, The University of Edinburgh, Edinburgh EH9 3JW, U.K.

Djerfisherite is a K-Cl-bearing sulfide that is present in both ultra-reduced extraterrestrial enstatite meteorites (enstatite chondrites or achondrites) and reduced terrestrial alkaline intrusions, kimberlites, ore deposits, and skarns. Major element chemistry of two terrestrial occurrences of djerfisherite (from the Ilímaussaq and Khibina alkaline igneous suites) and three extraterrestrial examples of djerfisherite have been determined and combined with petrographic characterization and element mapping to unravel three discrete modes of djerfisherite formation. High Fe/Cu is characteristic of extraterrestrial djerfisherite and low Fe/Cu is typical of terrestrial djerfisherite. Ilímaussaq djerfisherite, which has high-Fe contents (~55 wt%) is the exception. Low Ni contents are typical of terrestrial djerfisherite due to preferential incorporation of Fe and/or Cu over Ni, but Ni contents of up to 2.2 wt% are measured in extraterrestrial djerfisherite. Extensive interchange between K and Na is evident in extraterrestrial samples, though Na is limited (<0.15 wt%) in terrestrial djerfisherite. We propose three setting-dependent mechanisms of djerfisherite formation: primitive djerfisherite as a product of nebula condensation in the unequilibrated E chondrites; formation by extensive K-metasomatism in Khibina djerfisherite; and as a product of primary “unmixing” due to silicate-sulfide immiscibility for Ilímaussaq djerfisherite. There are several important reasons why a deeper understanding of the petrogenesis of this rare and unusual mineral is valuable: (1) its anomalously high K-contents make it a potential target for Ar-Ar geochronology to constrain the timing of metasomatic alteration; (2) typically high Cl-contents (~1.1 wt%) mean it can be used as a valuable tracer of fluid evolution during metasomatic alteration; and (3) it may be a potential source of K and magmatic Cl in the sub-continental lithospheric mantle (SCLM), which has implications for metal solubility and the generation of ore deposits.

Reference
Clay PL, O’Driscoll B, Upton GJ, Busemann H (2014) Characteristics of djerfisherite from fluid-rich, metasomatized alkaline intrusive environments and anhydrous enstatite chondrites and achondrites. American Mineralogist 99, 1683-1693
Link to Article [doi:10.2138/am.2014.4700]

Copyright: The Mineralogical Society of America