¹Nick Choksi,^1,2Eugene Chiang,³Harold C Connolly,⁴Jr, Zack Gainsforth,⁴Andrew J Westphal
Monthly Notices of the Royal Astronomical Society 503, 3297-3308 Link to Article [https://doi.org/10.1093/mnras/stab503]
¹Astronomy Department, Theoretical Astrophysics Center, and Center for Integrative Planetary Science, University of California, Berkeley, CA 94720, USA
²Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
³Department of Geology, School of Earth and Environment, Rowan University, Glassboro, NJ 08028, USA
⁴Space Sciences Laboratory, University of California, Berkeley, CA 94720, USA

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¹Alessandra Migliorini,¹M C De Sanctis,²T A Michtchenko,³D Lazzaro,⁴M Barbieri,⁵D Mesa,⁵M Lazzarin,⁵F La Forgia
Monthly Notices of the Royal Astronomical Society (in press) Link to Article [https://doi.org/10.1093/mnras/stab332]
¹Institute of Space Astrophysics and Planetology, IAPS-INAF, Rome, Italy
²IAG, Universidade de Sao Paulo, São Paulo, Brazil
³Observatório Nacional, COAA, Rio de Janeiro, Brazil
⁴Instituto de Astonomía y Ciencias planetarias de Atacama, Univesity of Atacama, Copiapo, Chile
⁵Observatory of Padova, INAF-OAPd, Padova, Italy
⁶Department of Physics and Astronomy “G. Galilei”, University of Padova, Padova, Italy

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^1,2Safoura Tanbakouei,^1,2Josep M. Trigo-Rodríguez,³Jürgen Blum,⁴Iwan Williams,⁵Jordi Llorca
Astronomy & Astrophysics 641, A58 Link to Article [DOI https://doi.org/10.1051/0004-6361/202037996]
¹Institute of Space Sciences (ICE-CSIC), Campus UAB, C/ Can Magrans s/n, 08193 bellaterra (Barcelona), Catalonia, Spain
²Institut d’Estudis Espacials de Catalunya (IEEC), C/ Gran Capità, 2-4, Ed. Nexus, desp. 201, 08034 Barcelona, Catalonia, Spain
³Institut für Geophysik und extraterrestrische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
⁴School of Physics and Astronomy, Queen Mary, University of London, Mile End Rd. London E1 4NS, UK
⁵Institute of Energy Technologies, Department of Chemical Engineering and Barcelona Research Center in Multiscale Science and Engineering, Universitat Politècnica de Catalunya- BarcelonaTech, Catalonia, Spain

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¹Pavol Matlovič,^2,3Julia de Leon,^2,3Hissa Medeiros,^2,4Marcel Popescu,^2,3Juan Luis Rizos,^5,6Jad-Alexandru Mansour
Astronomy & Astrophysics 643, A107 Link to Article [DOI https://doi.org/10.1051/0004-6361/202039263]
¹Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia
²Instituto de Astrofísica de Canarias (IAC), C/Vía Láctea sn, 38205 La Laguna, Spain
³Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
⁴Astronomical Institute of the Romanian Academy, 5 Cuţitul de Argint, 040557 Bucharest, Romania
⁵International Centre for Advanced Training and Research in Physics, Magurele 077125, Ilfov, Romania
⁶Faculty of Science and Engineering, University of Groningen, Nijenborgh 9, 9747 AG Groningen, The Netherlands

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¹Axel Wittmann et al. (>10)
Earth and Planetary Science Letters 575, 117201 Link to Article [https://doi.org/10.1016/j.epsl.2021.117201]
¹Eyring Materials Center, Arizona State University, 1001 S. McAllister Avenue, Tempe, AZ 85287-8301, USA
Copyright Elsevier

Zircon is a precise chronometer and prominent recorder of impact deformation. However, many impact-induced features in zircon are poorly calibrated, sometimes due to contradicting experimental data, in other instances due to the lack of systematic studies of impact-deformed zircon. To resolve issues with the shock petrographic use of zircon, we classified impact deformation features in 429 zircon grains in a continuous drill core of uplifted, granitic bedrock in the peak ring of the 200-km-diameter K-Pg Chicxulub impact structure. Following initial identification in backscattered electron (BSE) images, Raman spectroscopy and electron backscatter diffraction confirmed one reidite-bearing zircon grain. Quartz-based shock barometry indicates the host rock of this zircon-reidite grain experienced an average shock pressure of 17.5 GPa. A survey of BSE images of 429 ZrSiO4 grains found brittle deformation features are ubiquitous, with planar fractures in one to five sets occurring in 23% of all zircon grains. Our survey also reveals a statistically significant correlation of the occurrence of planar fractures in zircon with the types of host materials. Compared to zircon enclosed in mafic, higher density mineral hosts, felsic, low-density minerals show a much higher incidence of zircon with planar fractures. This finding suggests amplification of pressure due to shock impedance contrasts between zircon and its mineral hosts. Using the impedance matching method, we modeled the shock impedance pressure amplification effect for zircon inclusions in Chicxulub granitic hosts. Our modeling indicates shock impedance could have amplified the average 17.5 GPa shock pressure in a zircon inclusion in quartz or feldspar in the Chicxulub granitic rocks to 24 ± 1 GPa, suggesting that reidite in these rocks formed between 17.5 and 25 GPa. In essence, our study of impedance-induced shock pressure amplification in zircon assemblages, including the onset of reidite formation, details how shock impedance in mineral associations can be quantified to refine shock pressure estimates.

¹E.Das,¹J.F.Mustard,^1,2J.D.Tarnas,¹A.C.Pascuzzo,¹C.H.Kremer
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114720]
¹Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI 02912, United States of America
²NASA Jet Propulsion Laboratory, California Institute of Technology, United States of America
Copyright Elsevier

The Olympia Undae sand sea contains the largest known deposit of gypsum discovered on the surface of Mars. The origin of this gypsum, a hydrated sulfate mineral requiring liquid water for its formation, remains largely unconstrained. We examine the hypothesis that gypsum was derived from the early-Amazonian aged Basal Unit, which is suggested to contain hydrated sulfates. Previous attempts to detect hydrated sulfates in the Basal Unit using CRISM and OMEGA data have been largely inconclusive. In this paper, we characterize the hydrated sulfate mineralogy of the Basal Unit using the Guided Endmember Extraction (GEEn) method which can detect target mineral spectra in mixed environments that obscure absorptions characteristic of certain minerals. In this paper, we outline a novel workflow for the application of GEEn to a set of CRISM images from the Olympia Cavi region and present spectral evidence for the presence of polyhydrated sulfates in the Basal Unit. We validate the applied GEEn workflow using CRISM data from various regions on Mars where sulfates have previously been detected. Non-linear mixture modeling is used to determine that spectra of the Basal Unit are best modeled as a spectral mixture of water-ice, sand/dust, mafic dune material, gypsum, and polyhydrated magnesium sulfate⁎. These sulfate detections could indicate the presence of liquid water in the polar region during the Amazonian.1

¹A. A. Simon,¹H. H. Kaplan,²E. Cloutis,³V. E. Hamilton,⁴C. Lantz,¹D. C. Reuter,⁵D. Trang,^6,7S. Fornasier,⁸B. E. Clark,⁹D. S. Lauretta
Astronomy & Astrophysics 644, A148 Link to Article [DOI https://doi.org/10.1051/0004-6361/202039688]
¹Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA
²Department of Geography, University of Winnipeg, Winnipeg, Canada
³Southwest Research Institute, Boulder, CO, USA
⁴Institut d’Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
⁵Hawai’i Institute of Geophysics and Planetology, University of Hawai’i at Manoa, Honolulu, HI, USA
⁶LESIA, Observatoire de Paris, Université PSL, CNRS, Université de Paris, Sorbonne Université, 5 place Jules Janssen, 92195 Meudon, France
⁷Institut Universitaire de France (IUF), 1 rue Descartes, 75231 Paris Cedex 05, France
⁸Department of Physics and Astronomy, Ithaca College, Ithaca, NY, USA
⁹Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA

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^1,2S.Fornasier et al. (>10)
Astronomy & Astrophysics 644, A142 Link to Article [DOI https://doi.org/10.1051/0004-6361/202039552]
¹LESIA, Observatoire de Paris, Université PSL, CNRS, Université de Paris, Sorbonne Université, 5 place Jules Janssen, 92195 Meudon, France
²Institut Universitaire de France (IUF), 1 rue Descartes, 75231 Paris Cedex 05, France

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¹Conel M.O’D. Alexander,^1,2Jonathan G. Wynn,¹Roxane Bowden
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13746]
¹Earth and Planets Laboratory, Carnegie Institution for Science, 5241 Broad Branch Road, NW, Washington, District of Columbia, 20015 USA
²Division of Earth Sciences, National Science Foundation, 2415 Eisenhower Avenue, Alexandria, Virginia, 22314 USA
Published by arrangement with John Wiley & Sons

The bulk S elemental abundances and δ34S values for 83 carbonaceous chondrites (mostly CMs and CRs) and Semarkona (LL3.0) are reported. In addition, the S elemental abundances and δ34S values of insoluble organic material (IOM) isolated from 25 carbonaceous chondrites (CMs, CRs, and three ungrouped) are presented. The IOM only contributes 2–7% of the S to the bulk meteorites analyzed and exhibits no systematic variations. The average group bulk S abundances are similar to previous measurements. In-group variations likely reflect variations in matrix abundances, as well as parent body processes and weathering. The S and C abundances are roughly correlated and scatter about a mixing line between CI-like matrix and C-free and S-depleted chondrules. Systematic deviations from this mixing line may indicate different degrees of heating of matrix material in the nebula. There are no systematic variations in average group δ34S values, in contrast to what is seen for the volatile chalcophiles Zn, Te, Se, and Ag, as well as the less volatile siderophile Cu. Renormalization of the elemental and isotopic compositions indicates that the elemental and isotopic fractionations of Zn, Te, and Ag were controlled by the same process, whereas Se is intermediate in its behavior between these three elements and S. The isotopic fractionations could be associated with diffusion of volatile chalcophiles into sulfide at the end of chondrule formation. Copper appears to be distinct in its behavior from the chalcophiles, perhaps because it is more refractory and more siderophile.

¹Logan Jaeger et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13747]
¹Space Sciences Laboratory, University of California at Berkeley, Berkeley, California, 94720 USA
Published by arrangement with John Wiley & Sons

NASA’s Stardust mission utilized a sample collector composed of aerogel and aluminum foil to return cometary and interstellar particles to Earth. Analysis of the aluminum foil begins with locating craters produced by hypervelocity impacts of cometary and interstellar dust. Interstellar dust craters are typically less than one micrometer in size and are sparsely distributed, making them difficult to find. In this paper, we describe a convolutional neural network based on the VGG16 architecture that achieves high specificity and sensitivity in locating impact craters in the Stardust interstellar collector foils. We evaluate its implications for current and future analyses of Stardust samples.