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]