¹David W. Mittlefehldt,²Richard C. Greenwood,³Eve L. Berger,⁴Loan Le,⁴Zhan X. Peng,^4,5D. Kent Ross
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13730]

¹Mail code XI3, Astromaterials Research Office, NASA/Johnson Space Center, Houston, Texas, 77058 USA
²Planetary and Space Sciences, School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA UK
³Texas State University—Jacobs JETS Contract, NASA Johnson Space Center, Houston, Texas, 77058 USA
⁴Jacobs JETS-NASA Johnson Space Center, Houston, Texas, 77058 USA
⁵UTEP-CASSMAR, El Paso, Texas, 79968 USA
Published by arrangement with John Wiley & Sons

We report petrologic studies and oxygen isotope analyses of normal and anomalous eucrites, termed eucrite-type achondrites. Petrologically anomalous eucrite-type achondrites can have normal oxygen isotope compositions, and vice versa. Two basaltic eucrites with normal oxygen isotope compositions contain pyroxenes with anomalous Fe/Mn engendered by parent body processes acting on normal eucrites: solid-state reduction by S gas in EET 87542, and reduction during crystallization by magmatic S in QUE 94484. Cataclastic basaltic breccias PCA 82502 and PCA 91007 are paired (petrology, anomalous oxygen). Although isotopically like Pasamonte, they are petrologically distinct. We confirm the petrological and isotopic anomalies of cumulate gabbro EET 92023; likely formed by impact melting of mixed cumulate and basaltic materials. Many main group eucrites include plagioclases that retain near-liquidus compositions despite metamorphic overprinting. Stannern group eucrites contain more sodic plagioclase, which is consistent with the melt hybridization hypothesis for Stannern group magma formation. The lack of more calcic plagioclase suggests reactive exchange of the anorthite component of the primary melt with the albitic component of the crust. Asteroids that are modestly different in composition can produce virtually indistinguishable basalts, providing a ready explanation for the eucrite-type achondrite suite. Small stochastic variations in petrologic evolution can cause substantial differences in rocks produced on an asteroid.

¹Y Ellinger,¹M Lattelais,¹F Pauzat,²J-C Guillemin,³B Zanda
Monthly Notices of the Royal Astronomical Society 502, 4064–4073 Link to Article [https://doi.org/10.1093/mnras/stab217]
¹Sorbonne Université, CNRS – UMR7616, LCT, 4 Place Jussieu, F-75005 Paris, France
²Univ Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR UMR6226, F-35000 Rennes, France
³Sorbonne Université, CNRS – UMR7202, MNHN, 61 rue Buffon, F-75005 Paris, France

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^1,2,3Jarmo Moilanen,^1,2,3,4Maria Gritsevich,³Esko Lyytinen
Monthly Notices of the Royal Astronomical Society 503, 3337–3350 Link to Article [https://doi.org/10.1093/mnras/stab586]
¹Finnish Geospatial Research Institute (FGI), Geodeetinrinne 2, FI-02430 Masala, Finland
²University of Helsinki, Faculty of Science, Gustaf Hällsrömin katu 2, FI-00014 Helsinki, Finland
³Finnish Fireball Network, Ursa Astronomical Association, Kopernikuksentie 1, FI-00130 Helsinki, Finland
⁴Institute of Physics and Technology, Ural Federal University, Ekaterinburg 620002, Russia

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¹Sujoy Ghosh¹Kishan Tiwari,²Masaaki Miyahara,³Arno Rohrbach,³Christian Vollmer,⁴Vincenzo Stagno,⁵Eiji Ohtani,⁶Dwijesh Ray
Proceedings of the National Academy of the United States of America (in press) Link to Article [https://doi.org/10.1073/pnas.2108736118]
¹Department of Geology and Geophysics, Indian Institute of Technology Kharagpur, Kharagpur 721302, India;
²Graduate School of Advanced Science and Engineering, Hiroshima University, Hiroshima 739-8526, Japan;
³Institut für Mineralogie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany;
⁴Department of Earth Sciences, Sapienza University of Rome, Rome 00185, Italy;
⁵Department of Earth and Planetary Materials Science, Graduate School of Sciences, Tohoku University, Sendai 980-8578, Japan;
⁶Planetary Sciences Division, Physical Research Laboratory, Ahmedabad 380009, India

Bridgmanite, the most abundant mineral of the Earth’s lower mantle, has been reported in only a few shocked chondritic meteorites; however, the compositions of these instances differ from that expected in the terrestrial bridgmanite. Here, we report the first natural occurrence of Fe-bearing aluminous bridgmanite in shock-induced melt veins within the Katol L6 chondrite with a composition that closely matches those synthesized in high-pressure and temperature experiments over the last three decades. The Katol bridgmanite coexists with majorite and metal-sulfide intergrowths. We found that the natural Fe-bearing aluminous bridgmanite in the Katol L6 chondrite has a significantly higher Fe³⁺/ΣFe ratio (0.69 ± 0.08) than coexisting majorite (0.37 ± 0.10), which agrees with experimental studies. The Katol bridgmanite is arguably the closest natural analog for the bridgmanite composition expected to be present in the Earth’s lower mantle. Textural observations and comparison with laboratory experiments suggest that the Katol bridgmanite formed at pressures of ∼23 to 25 gigapascals directly from the chondritic melt generated by the shock event. Thus, the Katol L6 sample may also serve as a unique analog for crystallization of bridgmanite during the final stages of magma ocean crystallization during Earth’s formation.

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