^1,8Vishnu Reddy, ^2,8Juan A. Sanchez, ³Roberto Furfaro, ^4,8Richard P. Binzel, ^5,8Thomas H. Burbine, ^2,8Lucille Le Corre, ^2,8Paul S. Hardersen, ⁶William F. Bottke, ⁷Marina Brozovic
The Astronomical Journal 155, 140 Link to Article [https://doi.org/10.3847/1538-3881/aaaa1c]
¹Lunar and Planetary Laboratory, University of Arizona, 1629 E University Boulevard, Tucson, AZ 85721-0092, USA
²Planetary Science Institute, 1700 East Fort Lowell Road, Tucson, AZ 85719, USA
³Systems and Industrial Engineering, University of Arizona, 1127 E. James E. Rogers Way, Tucson, AZ 85721-0020, USA
⁴Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
⁵Department of Astronomy, Mount Holyoke College, South Hadley, MA 01075, USA
⁶Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302, USA
⁷Jet Propulsion Laboratory, 4800 Oak Grove Drive, Mail Stop 301-120, Pasadena, CA 91109-8099, USA
⁸Visiting Astronomer at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration.

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

^1,2E.S. Steenstra, ¹A.X. Seegers, ¹J. Eising, ¹B.G.J. Tomassen, ¹F.P.F. Webers, ³J. Berndt, ³S. Klemme, ⁴S. Matveev, ¹W. van Westrenen
Geochmica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2018.04.008]
¹Faculty of Science, Vrije Universiteit, Amsterdam, The Netherlands
²The Geophysical Laboratory, Carnegie Institution of Science, Washington D. C., United States
³Institute of Mineralogy, University of Münster, Germany
⁴Faculty of Geosciences, Utrecht University, The Netherlands
Copyright Elsevier

Sulfur concentrations at sulfide saturation (SCSS) were determined for a range of low- to high-Ti lunar melt compositions (synthetic equivalents of Apollo 14 black and yellow glass, Apollo 15 green glass, Apollo 17 orange glass and a late-stage lunar magma ocean melt, containing between 0.2 and 25 wt.% TiO2) as a function of pressure (1 – 2.5 GPa) and temperature (1683 – 1883 K). For the same experiments, sulfide-silicate partition coefficients were derived for elements V, Cr, Mn, Co, Cu, Zn, Ga, Ge, As, Se, Mo, Sn, Sb, Te, W and Pb. The SCSS is a strong function of silicate melt composition, most notably FeO content. An increase in temperature increases the SCSS and an increase in pressure decreases the SCSS, both in agreement with previous work on terrestrial, lunar and martian compositions. Previously reported SCSS values for high-FeO melts were combined with the experimental data reported here to obtain a new predictive equation to calculate the SCSS for high-FeO lunar melt compositions. Calculated SCSS values, combined with previously estimated S contents of lunar low-Ti basalts and primitive pyroclastic glasses, suggest their source regions were not sulfide saturated. Even when correcting for the currently inferred maximum extent of S degassing during or after eruption, sample S abundances are still >700 ppm lower than the calculated SCSS values for these compositions. To achieve sulfide saturation in the source regions of low-Ti basalts and lunar pyroclastic glasses, the extent of degassing of S in lunar magma would have to be orders of magnitude higher than currently thought, inconsistent with S isotopic and core-to-rim S diffusion profile data. The only lunar samples that could have experienced sulfide saturation are some of the more evolved A17 high-Ti basalts, if sulfides are Ni- and/or Cu rich.

Sulfide saturation in the source regions of lunar melts is also inconsistent with the sulfide-silicate partitioning systematics of Ni, Co and Cu. Segregation of significant quantities of (non)-stoichiometric sulfides during fractional crystallization would result in far larger depletions of Ni, Co and Cu than observed, whereas trends in their abundances are more likely explained by olivine fractionation. The sulfide exhaustion of the lunar magma source regions agrees with previously proposed low S abundances in the lunar core and mantle, and by extension with relatively minor degassing of S during the Moon-forming event. Our results support the hypothesis that refractory chalcophile and highly siderophile element systematics of low-Ti basalts and pyroclastic glasses reflect the geochemical characteristics of their source regions, instead of indicating the presence of residual sulfides in the lunar interior.

¹Aaron J. Cavosie, ¹Nicholas E. Timms, ²Timmons M. Erickson, ^3,4Christian Koeberl
Geology 46, 203-206 Link to Article [DOI: https://doi.org/10.1130/G39711.1]
¹The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University, Perth, WA 6102, Australia
²Lunar and Planetary Institute, Universities Space Research Association, Houston, Texas 77058, USA
³Natural History Museum, 1010 Vienna, Austria
⁴Department of Lithospheric Research, University of Vienna, 1090 Vienna, Austria

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

¹Simon M. Drake, ¹Andrew D. Beard, ²Adrian P. Jones, ³David J. Brown, ⁴A. Dominic Fortes, ⁵Ian L. Millar, ¹Andrew Carter, ¹Jergus Baca, ¹Hilary Downes
Geology 46, 171-174 Link to Article [DOI: https://doi.org/10.1130/G39452.1]
¹School of Earth and Planetary Sciences, Birkbeck College, University of London, Malet Street, Bloomsbury, London WC1E 7HX, UK
²Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK
³School of Geographical and Earth Sciences, University of Glasgow, Lilybank Gardens, Glasgow G12 8QQ, UK
⁴ISIS Neutron Facility, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Chilton, Didcot, Oxfordshire OX11 OQX, UK
⁵British Geological Survey, Natural Environment Research Council, Keyworth, Nottingham NG12 5GC, UK

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

^1,2,3Jay Shah et al. (>10)*
Nature Communications 9, 1173 Link to Article [doi:10.1038/s41467-018-03613-1]
¹Department of Earth Science and Engineering, Imperial College London, London, SW7 2BP, UK
²Department of Earth Sciences, Natural History Museum, London, SW7 5BD, UK
³Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, UK

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

^1,2Laurette Piani, ¹Hisayoshi Yurimoto, ³Laurent Remusat
Nature Astronomy 2, 317-323 Link to Article [doi:10.1038/s41550-018-0413-4]
¹Department of Natural History Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
²CPRG, UMR 7358 CNRS, Université de Lorraine, Vandoeuvre-lès-Nancy, France
³Muséum National d’Histoire Naturelle, Sorbonne Université, UMR CNRS 7590, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, Paris, France

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

¹Joseph P. Smith, ²Frank C. Smith, ¹Karl S. Booksh
Applied Spectroscopy 72, 404-419 Link to Article [https://doi.org/10.1177/0003702817721715]
¹Department of Chemistry & Biochemistry, University of Delaware, Newark, DE, USA
²Department of Geological Sciences, University of Delaware, Newark, DE, USA

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

^1,2Kathrin Markus, ^1,3Lyuba Moroz, ¹Gabriele Arnold, ^1,4Daniela Henckel, ²Harald Hiesinger, ⁵Arno Rohrbach, ⁵Klemme Stephan
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2018.04.006]
¹DLR, Institut für Planetenforschung, Berlin, Germany
²Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Germany
³Institut für Erd- und Umweltwissenschaften, University of Potsdam, Potsdam, Germany
⁴Institut für Geologische Wissenschaften, Freie Universität Berlin, Germany
⁵Institut für Mineralogie, Westfälische Wilhelms-Universität Münster, Germany

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

^1,2D.Perna, ²M.A.Barucci, ²M.Fulchignoni, ^2,3M.Popescu, ^2,4I.Belskaya,²S.Fornasier, ²A.Doressoundiram, ^2,5C.Lantz,²F.Merlin
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2018.03.008]
¹INAF – Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone, Italy
²LESIA – Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 Place Jules Janssen, 92195 Meudon, France
³Astronomical Institute of the Romanian Academy, 5 Cuţitul de Argint, 040557 Bucharest, Romania
⁴Institute of Astronomy, Kharkiv V.N. Karazin National University, Sumska Str. 35, Kharkiv 61022, Ukraine
⁵Institut d’Astrophysique Spatiale, CNRS, UMR-8617, Université Paris-Sud, bâtiment 121, 91405 Orsay, France

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

¹A. Gaudin, ^2,3E. Dehouck, ⁴O. Grauby, ¹N. Mangold
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.01.029]
¹Laboratoire de Planétologie et Géodynamique de Nantes (LPGN), CNRS/Université de Nantes, 44322 Nantes, France
²IRAP, Université de Toulouse, CNRS, UPS, CNES, Toulouse, France
³Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, UMR 5276, CNRS, Université Lyon 1, ENS Lyon, Villeurbanne, France
⁴Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), CNRS/Aix-Marseille Université, Campus de Luminy, 13288 Marseille, France
Copyright Elsevier

Laboratory experiments are useful to constrain the environmental parameters that have allowed the formation of the ancient hydrous mineralogical assemblages observed at the surface of Mars, which are dominated by ferric smectites. Weathering under a dense CO2 atmosphere on early Mars is a process frequently invoked to explain their formation, but has proven difficult to test in the laboratory due to low reaction rates. Here, we present a long-term weathering experiment (470 days, at 45°C) of forsteritic olivine specially designed to increase as much as possible the amount of reaction products and thus allow their detailed mineralogical, petrological and chemical characterization by FTIR, SEM and TEM. Our results show the formation of crystalline smectites both under 1 bar of CO2 and under ambient air. However, important differences are observed between the two types of conditions. The smectite formed under CO2 has an average chemical formula per half unit-cell of Si3.92Al0.16Fe3+0.78Mg1.66 Cr0.01Ni0.06K0.04Ca0.04.O10(OH)2. It is thus intermediate between a trioctahedral Mg-rich saponite and a dioctahedral ferric smectite. It is also clearly enriched in Fe compared its counterpart formed under ambient air, which has an average chemical formula per half unit-cell of Si3.68Al0.12Fe3+0.37Mg2.61Cr0.01Ni0.02K0.04Ca0.25.O10(OH)2. This result demonstrates that the enrichment in Fe observed for Martian smectites is to be expected if they were formed by low-temperature weathering under a dense CO2 atmosphere. Another difference is the nature of the accompanying phases, which includes amorphous silica (in the form of opal spheres 10 to 100 nm in diameter) and Mg-carbonates under CO2, but are limited to rare kaolinite under ambient air. The observation of kaolinite particles under air and the significant amount of Al measured in smectites under both atmospheres, despite the Al-poor nature of the initial material, shows that this element is easily concentrated by low-temperature weathering processes. At a larger scale, this concentration mechanism could be responsible for the formation of Al-rich upper horizons, as frequently observed on Mars.