¹Thomas, R., ²Davidson, P.
Mineralogy and Petrology (in Press) Link to Article [DOI: 10.1007/s00710-018-0598-3]
¹Helmholtz-Centre Potsdam, German Research Centre for Geoscience – GFZ, Section 4.3. Chemistry and Physics of Earth Materials, Telegrafenberg, Potsdam, Germany
²CODES, Centre for Ore Deposit and Earth Science, University of Tasmania, Hobart, Australia

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^1,2Yelisseyev, A.P., ¹Afanasyev, V.P.,^2,3Gromilov, S.A.
Diamond and Related Materials 89, 10-17 Link to Article [DOI: 10.1016/j.diamond.2018.08.003]
¹V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, 3 Koptyug ave., Novosibirsk, Russian Federation
²Novosibirsk State University, 2 Pirogova str., Novosibirsk, Russian Federation
³A.V. Nikolayev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, 3 Lavrentyev ave., Novosibirsk, Russian Federation

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¹López-Acosta, D., ^2,3Frías, J.M.,^3,4Baonza, V.G., ^1,4Hernández, R.L
Geogaceta 63 59-62 Link to Article [ISSN: 0213683X]
¹Departamento de Cristalografía y Mineralogía, Facultad Ciencias Geológicas, UCM., Madrid, Spain
²Departamento de Geodinámica, Facultad Ciencias Geológicas, UCM, Madrid, Spain
³Instituto de Geociencias IGEO (CSIC, UCM), Madrid, Spain
⁴Departamento de Química Física I, Facultad Ciencias Químicas, UCM, Madrid, Spain

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^1,2H.Jens Hoeijmakers et al. (>10)
Nature (in Press) Link to Article [https://doi.org/10.1038/s41586-018-0401-y]
¹Observatoire astronomique de l’Université de Genève, Versoix, Switzerland
²University of Bern, Center for Space and Habitability, Bern, Switzerland

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¹Zhong-Yi Lin, ¹Wing-Huen Ip, ¹Chow-Choong Ngeow
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2018.07.012]
¹No. 300, Zhongda Rd., Zhongli Dist, Taoyuan City, 32001, Taiwan

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^1,2,3,4Gordon R. Osinski et al. (>10)
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2018.07.011]
¹Centre for Planetary Science and Exploration, University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada
²Department of Earth Sciences, University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada
³Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada
⁴Department of Electrical and Computer Engineering, University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B9, Canada

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¹M. N. Rao, ²L. E. Nyquist, ^3,4D. K. Ross, ^5,6S. R. Sutton, ⁷P. Hoppe, ⁸C. Y. Shih, ⁹S. J. Wentworth, ¹⁰D. H. Garrison
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13177]
¹SCI, Johnson Space CenterHouston, Texas, USA
²XI/NASA Johnson Space CenterHouston, Texas, USA
³Jacob JETS, NASA Johnson Space CenterHouston, Texas, USA
⁴UTEP–CASSMAREl Paso, Texas, USA
⁵Department of Geophysical Sciences, University of ChicagoChicago, Illinois, USA
⁶CARS, Argonne National LaboratoryArgonne, Illinois, USA
⁷Max‐Planck Institute für Chemie, Mainz, Germany
⁸Jacobs, Johnson Space CenterHouston, Texas, USA
⁹HEPCO, Jacobs Engineering, Johnson Space CenterHouston, Texas, USA
¹⁰Barios Technology, NASA, Johnson Space CenterHouston, Texas, USA
Published by arrangement with John Wiley & Sons

Martian regolith components are found in some impact melts (IM) containing Martian atmospheric gases in the shergottites Elephant Moraine (EET) 79001, Tissint, Zagami, and Shergotty. Excess sulfur abundances provide strong indicators for the presence of an exogenous component. High sulfur abundances and the SO3‐SiO2 correlation in polished thin section (PTS) EET 79001,507 (here #507) are comparable to those in Martian soils. Correlations of SO3 with FeO in #507 from Lithology B and of CaO and Al2O3 in EET 79001,506 (here #506) from Lithology A suggest the possible occurrence of two varieties of sulfate‐bearing phases in impact‐melt precursors. Fe/S (atomic) ratios of 1.02–1.34 determined in several sulfide blebs in #507 differ from those determined in igneous sulfides (Fe/S = 0.92), and suggest that most sulfide blebs in #507 are not related to igneous sulfides. Fe/S (atomic) ratios in a Tissint glass range from ~0.5 (pyrite) to >1.1 suggesting a mixture of sulfur‐bearing phases. S K‐XANES spectra of the blebs in EET 79001 and Tissint glasses show that sulfur occurs as mixed amorphous sulfide and sulfite. The δ34S values and the 87Sr/86Sr (I) ratios determined in EET 79001 impact melts are consistent with the proposition that the sulfide blebs result from decomposition of secondary sulfates into sulfites during shock heating followed by reduction to sulfides by isentropic cooling. These results suggest the presence in some shergottites of extraneous regolith components containing oxidized S‐bearing species resembling sulfur species present in Martian soils.

¹A.P.Crósta, ^2,3W.U.Reimold,⁴M.A.R.Vasconcelos, ²N.Hauser, ¹G.J.G.Oliveira,¹M.V.Maziviero,⁵A.M.Góes
Chemie der Erde (in Press) Link to Article [https://doi.org/10.1016/j.chemer.2018.06.001]
¹State University of Campinas, Brazil
²University of Brasília, Brazil
³Natural History Museum – Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany
⁴Federal University of Bahia, Brazil
⁵University of São Paulo, Brazil
Copyright Elsevier

The Earth’s impact record is known to be rather limited in both time and space. There are ca. 190 impact structures currently known on Earth, representing a minor fraction of all the impact events that contributed to the initial formation of our protoplanet, and then to formation and modification of the surface of the planet. Moreover, the distribution of impact structures on Earth is manifestly uneven. One continent that stands out for its relatively small number of confirmed impact structures and impact ejecta occurrences is South America. The limited impact record for this large continent makes a robust case that there is a significant potential for further discoveries. Significant information on the impact record of South America is dispersed in different types of publications (journal articles, books, conferences abstracts, etc.), and in several languages, making it difficult to access and disseminate it among the geoscientific community. We aim to present a summary of the current knowledge of the impact record of this continent, encompassing the existing literature on the subject. It is published in two parts, with the first one covering an up-to-date introduction to impact cratering processes and to the criteria to identify/confirm an impact structure and related deposits. This is followed by a comprehensive analysis of the Brazilian impact structures. The Brazilian impact record accounts for the totality of the large structures of this kind currently confirmed in South America. The second part will examine the impact record of other countries in South America, provide information about a number of proposed impact structures, and review those that already have been discarded as not being formed by impact.

¹Derek W. G. Sears, ¹Alexander Sehlke, ^2,3Jon M. Friedrich, ⁴Mark L. Rivers, ²Denton S. Ebel
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13183]
¹NASA Ames Research Center/BAER Institute, Mountain View, California, USA
²American Museum of Natural History, New York, New York, USA
³Department of Chemistry, Fordham University, Bronx, New York, USA
⁴Center for Advanced Radiation Sources, University of Chicago, Argonne, Illinois, USA
Published by arrangement with John Wiley & Sons

The radiation record of extraterrestrial rocks provides important insights into their thermal and radiation history. For meteorites this relates to their orbits, thermal history, terrestrial age, preatmospheric size and shape, and possibly cosmic ray exposure age. For meteorites from the Moon and Mars, the radiation record allows insights into transit times. For Martian surface samples, the radiation record enables estimates of their sedimentary age. Despite this, there is a growing tendency to artificially expose these samples to large radiation doses by the use of X‐ray computed tomography (CT) imaging, often as part of their initial examination. In order to understand the effect of synchrotron microCT on meteorites, we placed samples of the Bruderheim L6 chondrite in the CT imaging port of the Advanced Photon Source at the Argonne National Laboratory, Argonne, Illinois. Monoenergetic X‐ray beams of 25 and 46 keV and a high flux broad spectrum beam were used. The synchrotron CT procedure exposed the samples to radiation doses significantly higher than the natural doses observed for meteorites (1670 to ~10,000 Gyr, compared to ~1000 Gyr for natural samples). It is clear that CT imaging, whether using a laboratory system as in our previous report or using the synchrotron source, makes measurement of the natural radiation record of the samples impossible. Samples should not be placed in a CT scanner without due consideration of the loss of unique information for these valuable extraterrestrial samples.

¹Julie Castillo‐Rogez, ^2,3Marc Neveu, ⁴Harry Y. McSween, ⁵Roger R. Fu, ⁶Michael J. Toplis, ⁷Thomas Prettyman
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13181]
¹Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
²School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
³NASA Postdoctoral Management Program Fellow, NASA Headquarters, Washington, District of Columbia, USA
⁴Department of Earth and Planetary Sciences, The University of Tennessee in Knoxville, Knoxville, Tennessee, USA
⁵Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
⁶IRAP, Université de Toulouse, CNRS, UPS, Toulouse, France
⁷Planetary Science Institute, Tucson, Arizona, USA
Published by arrangement with John Wiley & Sons

Inspired by the recent results of the Dawn mission, thermodynamic models of rock alteration and brine evaporation have been used to help understand the conditions under which water–rock interaction took place within the dwarf planet Ceres. This analysis constrains Ceres’s early history and offers a framework within which future observations may be interpreted. A broad range of alteration conditions have been simulated using the Geochemist’s Workbench and PHREEQC software, associated with the FREZCHEM model that constrains the consequences of freezing the liquid phase in equilibrium with the observed mineralogical assemblage. Comparison of the modeling results with observed surface mineralogy at Ceres indicates advanced alteration under a relatively high fugacity of hydrogen, a conclusion that is consistent with predictions for, and observations of, large ice‐rich bodies. The simulations suggest production of methane that could help regulate the redox environment and possibly form clathrate hydrates upon freezing of the early ocean. The detection of localized occurrences of natrite (sodium carbonate) at the surface of Ceres provides key constraints on the composition of fluids that are necessarily alkaline. In addition, the combined hydrothermal and freezing simulations suggest that hydrohalite may be abundant in Ceres’s subsurface, similar to Earth’s polar regions. The global homogeneity of Ceres’s surface, made of material formed at depth, suggests a large‐scale formation mechanism, while local heterogeneities associated with impact craters and landslides suggest that some form of sodium carbonate and other salts are accessible in the shallow subsurface.