¹Petr Vítek, ²Carmen Ascaso, ³Octavio Artieda, ²Jacek Wierzchos
Analytical and Bioanalytical Chemistry 408, 4083 Link to Article [doi:10.1007/s00216-016-9497-9]
¹Global Change Research Institute, v.v.i.The Czech Academy of Sciences Brno Czech Republic
²Museo Nacional de Ciencias Naturales, CSIC Madrid Spain
³Departamento Biología Vegetal, Ecología y Ciencias de la Tierra Universidad de Extremadura Plasencia Spain

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¹Xunyu Zhang,^1,2Yunzhao Wu,³Ziyuan Ouyang,¹Roberto Bugiolacchi,²Yuan Chen,^2,4Xiaomeng Zhang,¹²Wei Cai,¹Aoao Xu,¹Zesheng Tang
Journal of Geophysical Research Planets (in Press) Link to Article [DOI: 10.1002/2016JE005051]
¹Space Science Institute, Macau University of Science and Technology, Macau, China
²School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, China
³National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China
⁴Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China
Published by arrangement with John Wiley & Sons

The last major phases of lunar volcanism occurred mainly in Oceanus Procellarum and Mare Imbrium, and produced spectrally unique medium-high titanium basalts. The composition and distribution of these basalts provide a record of the late stage thermal evolution of the Moon. To study the spectral and mineralogical variations of the late stage mare basalts, 31 distinct units were mapped employing a range of remote sensing data. Their inferred mineralogical characteristics were studied by analyzing the spectral features of small, fresh craters derived from the Moon Mineralogy Mapper (M3) data. The strongest olivine spectral signatures were found around Lichtenberg crater, while the units with the lowest olivine/pyroxene ratio occurred mainly in the southern Kepler crater and some local areas. In Oceanus Procellarum, the olivine/pyroxene ratio decreasesprogressively from the Lichtenberg crater to the southern units. The northern and southern units within Mare Imbrium have higher olivine/pyroxene ratios than the central ones. The inferred abundance of olivine appears to vary stratigraphically, with the younger flows being more olivine rich. However, the stratigraphically younger units around Euler crater in Mare Imbrium, which present as dark red hues in the Integrated Band Depth (IBD) image of M3, were found to have lower olivine/pyroxene ratios than the units around Lichtenberg crater (shown as light red hues) in Oceanus Procellarum. . It could be interpreted that the late stage mare basalts around Lichtenberg crater originated from a more olivine-rich source than those around Euler crater.

^1,2Yang Liu,¹Timothy D. Glotch,^1,3Noel A. Scudder,^1,4Meredith L. Kraner,¹Thomas Condus,⁵Raymond E. Arvidson,⁵Edward A. Guinness,⁶Michael J. Wolff,⁷Michael D. Smith
Journal of Geophysical Research Planets Link to Article [DOI: 10.1002/2016JE005028]
¹Department of Geosciences, Stony Brook University, Stony Brook, NY, USA
²Southwest Research Institute, San Antonio, TX, USA
³Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, USA
⁴Nevada Geodetic Laboratory, University of Nevada Reno, Reno, NV, USA
⁵Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri, USA
⁶Space Science Institute, Boulder, CO, USA
⁷NASA Goddard Spaceflight Center, Greenbelt, MD, USA
Published by arrangement with John Wiley & Sons

We present spectral unmixing results over the southwest Melas Chasma region, where a variety of hydrated minerals were identified. We use the DISORT radiative transfer model to simultaneously model Mars atmospheric gases, aerosols, and surface scattering and retrieve the single scattering albedos (SSAs) modeled by the Hapke bidirectional scattering function from CRISM data. We employ a spectral unmixing algorithm to quantitatively analyze the mineral abundances by modeling the atmospherically corrected CRISM SSAs using a non-negative least squares (NNLS) linear deconvolution algorithm. To build the spectral library used for spectral unmixing, we use the factor analysis and target transformation (FATT) technique to recover spectral end-members within the CRISM scenes. We investigate several distinct geologic units, including an interbedded poly- and monohydrated sulfate unit (interbedded unit 1) and an interbedded phyllosilicate-sulfate unit (interbedded unit 2). Our spectral unmixing results indicate that, polyhydrated sulfates in the interbedded unit 1 have a much lower abundance (~10%) than that of the surrounding unit (~20%) and thus may have been partially dehydrated into kieserite to form the interbedded strata, supporting a two-staged precipitation-dehydration formation hypothesis. In the interbedded unit 2 phyllosilicates have an abundance of ~40% and are interbedded with ~20% sulfates. The results, in combination with thermodynamic calculations performed previously, suggest that the interbedded phyllosilicates and sulfates likely formed through coupled basalt weathering and evaporation. The methodology developed in this study provides a powerful tool to derive the mineral abundances, aiming to better constrain the formation processes of minerals and past aqueous environment on Mars.

¹Carle M. Pieters, ²Sarah K. Noble
Journal of Geophysical Research Planets (in Press) Link to Article [DOI: 10.1002/2016JE005128]
¹Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI
²Planetary Science Division, NASA Headquarters, Washington, DC
Published by arrangement with John Wiley & Sons

Space weathering refers to alteration that occurs in the space environment with time. Lunar samples, and to some extent meteorites, have provided a benchmark for understanding the processes and products of space weathering. Lunar soils are derived principally from local materials but have accumulated a range of optically active opaque particles (OAOpq) that include nanophase metallic iron on/in rims formed on individual grains (imparting a red slope to visible and near-infrared reflectance) and larger iron particles (which darken across all wavelengths) such as are often found within the interior of recycled grains. Space weathering of other anhydrous silicate bodies, such as Mercury and some asteroids, produce different forms and relative abundance of OAOpq particles depending on the particular environment. If the development of OAOpq particles is minimized (such as at Vesta), contamination by exogenic material and regolith mixing become the dominant space weathering processes. Volatile-rich bodies and those composed of abundant hydrous minerals (dwarf planet Ceres, many dark asteroids, outer solar system satellites) are affected by space weathering processes differently than the silicate bodies of the inner solar system. However, the space weathering products of these bodies are currently poorly understood and the physics and chemistry of space weathering processes in different environments are areas of active research.

¹L.M.Thompson et al. (>10)*
Journal of Geophysical Research Planets (in Press) Link to Article [DOI: 10.1002/2016JE005055]
¹Planetary and Space Science Centre, University of New Brunswick, Fredericton, NB, Canada
Published by arrangement with John Wiley & Sons
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The Alpha Particle X-ray spectrometer (APXS) onboard the Curiosity rover at the Kimberley location within Gale crater, Mars, analyzed basaltic sandstones that are characterized by potassium enrichments of two to eight times estimates for average martian crust. They are the most potassic rocks sampled on Mars to date. They exhibit elevated Fe, Mg, Mn and Zn, and depleted Na, Al and Si. These compositional characteristics are common to other potassic sedimentary rocks analyzed by APXS at Gale, but distinct from other landing sites and martian meteorites. CheMin and APXS analysis of a drilled sample indicate mineralogy dominated by sanidine, Ca-rich and Ca-poor clinopyroxene, magnetite, olivine and andesine. The anhydrous mineralogy of the Kimberley sample, and the normative mineralogy derived from APXS of other Bathurst class rocks, together indicate provenance from one or more potassium-rich magmatic or impact-generated source rocks on the rim of Gale crater or beyond. Elevated Zn, Ge and Cu suggest that a localized area of the source region(s) experienced hydrothermal alteration, which was subsequently eroded, dispersed and diluted throughout the unaltered sediment during transport and deposition. The identification of the basaltic, high potassium Bathurst class and other distinct rock compositional classes by the APXS, attests to the diverse chemistry of crustal rocks within and in the vicinity of Gale crater. We conclude that weathering, transport and diagenesis of the sediment did not occur in a warm and wet environment, but instead under relatively cold and wet conditions, perhaps more fitting with processes typical of glacial/periglacial environments.

¹F.G. Carrozzo, ²G. Di Achille, ³F. Salese, ¹F. Altieri, ¹G. Bellucci
Icarus (in Press) Link to Article [http://dx.doi.org/10.1016/j.icarus.2016.09.001]
¹Istituto di Astrofisica e Planetologia Spaziali, INAF, Rome, Italy
²Osservatorio Astronomico di Teramo, INAF, Teramo, Italy
³International Research School of Planetary Sciences, Dipartimento di Ingegneria e Geologia, Università Gabriele D’Annunzio, Pescara, Italy
Copyright Elsevier

A variety of hydrothermal environments have been documented in terrestrial impact structures. Due to both past water interactions and meteoritic bombardment on the surface of Mars, several authors have predicted various scenarios that include the formation of hydrothermal systems. Geological and mineralogical evidence of past hydrothermal activity have only recently been found on Mars. Here, we present a geological and mineralogical study of the Auki Crater using the spectral and visible imagery data acquired by the CRISM (Compact Reconnaissance Imaging Spectrometer for Mars), CTX (Context Camera) and HiRISE (High Resolution Imaging Science Experiment) instruments on board the NASA MRO mission.

The Auki Crater is a complex crater that is ∼38 km in diameter located in Tyrrhena Terra (96.8°E and 15.7°S) and shows a correlation between its mineralogy and morphology. The presence of minerals, such as smectite, silica, zeolite, serpentine, carbonate and chlorite, associated with morphological structures, such as mounds, polygonal terrains, fractures and veins, suggests that the Auki Crater may have hosted a post impact-induced hydrothermal system. Although the distribution of hydrated minerals in and around the central uplift and the stratigraphic relationships of some morphological units could also be explained by the excavation and exhumation of carbonate-rich bedrock units as a consequence of crater formation, we favor the hypothesis of impact-induced hydrothermal circulation within fractures and subsequent mineral deposition. The hydrothermal system could have been active for a relatively long period of time after the impact, thus producing a potential transient habitable environment.

¹M. Nachon et al. (>10)*
Icarus (in Press) Link to Article [http://dx.doi.org/10.1016/j.icarus.2016.08.026]
¹Laboratoire de Planétologie et Géodynamique de Nantes, CNRS, UMR6112, Université de Nantes, 44322 Nantes, France
Copyright Elsevier
*Find the extensive, full author and affiliation list on the publishers website

The Curiosity rover’s campaign at Pahrump Hills provides the first analyses of lower Mount Sharp strata. Here we report ChemCam elemental composition of a diverse assemblage of post-depositional features embedded in, or cross-cutting, the host rock. ChemCam results demonstrate their compositional diversity, especially compared to the surrounding host rock: (i) Dendritic aggregates and relief enhanced features, characterized by a magnesium enhancement and sulfur detection, and interpreted as Mg-sulfates; (ii) A localized observation that displays iron enrichment associated with sulfur, interpreted as Fe-sulfate; (iii) Dark raised ridges with varying Mg- and Ca-enriched compositions compared to host rock; (iv) Several dark-toned veins with calcium enhancement associated with fluorine detection, interpreted as fluorite veins. (v) Light-toned veins with enhanced calcium associated with sulfur detection, and interpreted as Ca-sulfates. The diversity of the Pahrump Hills diagenetic assemblage suggests a complex post-depositional history for fine-grained sediments for which the origin has been interpreted as fluvial and lacustrine. Assessment of the spatial and relative temporal distribution of these features shows that the Mg-sulfate features are predominant in the lower part of the section, suggesting local modification of the sediments by early diagenetic fluids. In contrast, light-toned Ca-sulfate veins occur in the whole section and cross-cut all other features. A relatively late stage shift in geochemical conditions could explain this observation. The Pahrump Hills diagenetic features have no equivalent compared to targets analyzed in other locations at Gale crater. Only the light-toned Ca-sulfate veins are present elsewhere, along Curiosity’s path, suggesting they formed through a common late-stage process that occurred at over a broad area.

¹A. Bouvier, ²M. Boyet
Nature 537, 399–402   Link to Article  [doi:10.1038/nature19351]
¹University of Western Ontario, Department of Earth Sciences, Centre for Planetary Science and Exploration, London, Ontario N6A 3K7, Canada
²Clermont Université, Université Blaise Pascal, Laboratoire Magmas et Volcans, UMR CNRS 6524, Campus Universitaire des Cézeaux, 6 avenue Blaise Pascal, 63178 Aubière Cedex, France

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^1,2C. Burkhardt, ³L. E. Borg, ^2,3G. A. Brennecka, ^2,3Q. R. Shollenberger, ¹N. Dauphas ²T. Kleine
Nature 537, 394–398 Link to Article [doi:10.1038/nature18956]
¹Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago, Illinois 60637, USA
²Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Wilhelm Klemm-Strasse 10, 48149 Münster, Germany
³Lawrence Livermore National Laboratory, L231, Livermore, California 94550, USA

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^1,2Guénon, S., ^1,3Ramírez, J.G., ^1,4Basaran, A.C., ¹Wampler, J., ⁵Thiemens, M., ¹Schuller, I.K.
Journal of Superconductivity and Novel Magnetism (in Press) Link to Article [doi:10.1007/s10948-016-3708-7]
¹Department of Physics and Center for Advanced Nanoscience, University of California, La Jolla, San Diego, CA, United States
²CQ Center for Collective Quantum Phenomena and their Applications in LISA +, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, Tübingen, Germany
³Department of Physics, Universidad de los Andes, Bogotá, Colombia
⁴Department of Physics, Gebze Technical University, Gebze, Kocaeli, Turkey
⁵Department of Chemistry and Biochemistry, University of California, La Jolla, San Diego, CA, United States

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