^1,2Elizaveta Kovaleva, ³Hassan Helmy, ^4,5Said Belkacim,²Anja Schreiber, ²Franziska D.H. Wilke,²Richard Wirth
American Mineralogist 108, 1906-1923 Link to Article [http://www.minsocam.org/msa/ammin/toc/2023/Abstracts/AM108P1906.pdf]
¹Department of Earth Sciences, University of the Western Cape, Robert Sobukwe Road, 7535 Bellville, South Africa
²Helmholtz Centre Potsdam—GFZ German Research Centre for Geosciences, Telegrafenberg, D-14473 Potsdam, Germany
³Department of Geology, Minia University, 61519-Minia, Egypt
⁴LAGAGE Laboratory, Department of Geology, Faculty of Sciences, Ibn Zohr University, P.O. Box 28/S, 80 000, Agadir, Morocco
⁵Research Institute on Mines and Environment (RIME), Université du Québec en Abitibi-Témiscamingue, 445 Boul. Université, Rouyn-Noranda, Québec J9X 5E4, Canada
Copyright: The Mineralogical Society of America

The origin of Libyan Desert Glass (LDG) found in the western parts of Egypt close to the Libyan
border is debated in planetary science. Two major theories of its formation are currently competing:
(1) melting by airburst and (2) formation by impact-related melting. While mineralogical and textural
evidence for a high-temperature event responsible for the LDG formation is abundant and convincing, minerals and textures indicating high shock pressure have been scarce. This paper provides a
nanostructural study of the LDG, showing new evidence of its high-pressure and high-temperature
origin. We mainly focused on the investigation of Zr-bearing and phosphate aggregates enclosed within
LDG. Micro- and nanostructural evidence obtained with transmission electron microscopy (TEM) are
spherical inclusions of cubic, tetragonal, and orthorhombic (Pnma or OII) zirconia after zircon, which
indicate high-pressure, high-temperature decomposition of zircon and possibly, melting of ZrO2. Inclusions of amorphous silica and amorphous Al-phosphate with berlinite composition (AlPO4) within
mosaic whitlockite and monazite aggregates point at decomposition and melting of phosphates, which
formed an emulsion with SiO2 melt. The estimated temperature of the LDG melts was above 2750 °C,
approaching the point of SiO2 boiling. The variety of textures with different degrees of quenching immediately next to each other suggests an extreme thermal gradient that existed in LDG through radiation
cooling. Additionally, the presence of quenched orthorhombic OII ZrO2 provides direct evidence of
high-pressure (>13.5 GPa) conditions, confirming theory 2, the hypervelocity impact origin of the LDG.

^1,2M.D. Suttle,²A.J. King,²C.S. Harrison,^1,3Q.H.S. Chan,⁴A. Greshake,⁵R. Bartoschewitz,⁶A.G. Tomkins,⁷T. Salge,²P.F. Schofield,²S.S. Russell
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2023.09.024]
¹School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
²Planetary Materials Group, Natural History Museum, Cromwell Road, London, SW7 5BD, UK
³Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK
⁴Museum für Naturkunde, Leibniz-Institut für Evolutions und Biodiversitätsforschung, Invalidenstraße 43, 10115 Berlin, Germany
⁵Bartoschewitz Meteorite Laboratory, Weiland 37, D-38518 Gifhorn, Germany
⁶School of Earth, Atmosphere and Environment, Melbourne, Victoria, Australia
⁷Imaging and Analysis Centre, Natural History Museum, Cromwell Road, London, SW7 5BD, UK
Copyright Elsevier

The CY chondrites are a group of thermally metamorphosed carbonaceous chondrites. Although they share similarities with the CM and CI chondrites, their primary properties argue for a distinct classification. Previous studies have highlighted their isotopically heavy bulk compositions (δ17O=10 ‰, δ18O=21 ‰, Δ17O=0 ‰) and exceptionally high sulphide abundances (10-30 vol%). In this work we explore their petrography and alteration history. The CYs accreted low abundances of chondrules (15-20 area%) with average apparent diameters slightly larger (∼320-340 µm) than the CM chondrites. In contrast to the CMs, the CYs record an early episode of brecciation prior to the main window of aqueous alteration. Subsequent fluid activity produced a range of alteration extents with both CY2 and CY1 chondrites documented. Phyllosilicate minerals in the CYs were a mix of serpentine and saponite (including occurrences of Na-saponite) with minor quantities of chlorite (within chondrules). An initial generation of Fe-sulphides formed by sulfidation of metal, and by precipitation from S-rich fluids. Three generations of carbonates are recognized, an early generation that infilled voids left by brecciation and co-precipitated with sulphide, a later generation that co-precipitated with magnetite and a final Fe-Mg-bearing generation which formed large (>100 µm) clasts. Only the first-generation carbonates are found in the CY2s, while the CY1s preserve all three generations. Phosphates occur as Ca-apatite or rarely as Mg-apatite and have hydroxylapatite compositions, indicating low halogen activities in the alteration fluids. Refractory oxides (ilmenite and Cr-spinel) occur as precipitates adhering to the margins of phyllosilicates. They formed late in the alteration sequence and attest to oxidizing conditions. During the late-stages of aqueous alteration Fe-sulphides were replaced by magnetite. Thermal metamorphism (Stage II-IV: ∼300-750 °C) overprinted aqueous alteration leading to dehydration and recrystallization of the phyllosilicate matrix and the decomposition of some carbonate phases. Most Fe-sulphide grains survived heating without decomposition as initial partial decomposition from pyrrhotite to troilite under closed system conditions led to elevated ƒS2 gas and resulted in a stabilizing effect. Retrograde reactions between trapped S2 gas and metal/magnetite formed a final generation of Fe-sulphides. The survival of Fe-sulphides and their stochiometric troilite compositions are evidence for near-closed system heating. Analysis of organic matter by Raman spectroscopy supports an interpretation of short-duration heating (on the scale of minutes to days), at peak temperatures between 750-900 °C. Thus, an impact event was the most likely cause of metamorphic heating.

^1,2S. S. Rout,³J. Storz,⁴A. Davydok,³A. Bischoff,⁵T. John,⁴C. Krywka,⁶M. Ritter
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14082]
¹School of Earth and Planetary Sciences, National Institute of Science Education and Research, Khorda, India
²Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, India
³Institut für Planetologie, University of Münster, Münster, Germany
⁴Institute of Materials Physics, Helmholtz-Zentrum Hereon, Outstation DESY, Hamburg, Germany
⁵Freie Universität Berlin, Institut für Geologische Wissenschaften, Berlin, Germany
⁶Electron Microscopy Unit, Hamburg University of Technology, Hamburg, Germany
Published by arrangement with John Wiley & Sons

The origin of diamond in ureilites has been frequently debated. We investigated carbon phase assemblages (CPAs) in five ureilitic samples of the brecciated asteroid 2008 TC3, found within the Almahata Sitta (AHS) strewn field, by transmission electron microscopy, Raman spectroscopy, synchrotron X-ray diffraction, and cathodoluminescence. Samples MS-MU 006, MS-187, and MS-170, are of low to moderate shock degree (U-S2 and U-S3), and samples MS-MU 027 (U-S4) and MS-MU 045 (U-S5) have a higher shock degree. In MS-MU 006 and MS-187, we did not find any diamond grains. MS-170 contains disordered and distorted graphite with diamond grains up to 12 μm in size and containing inclusions of Fe,Ni-metal, FeS, Fe-phosphide, and Cr,Fe-oxide. These diamond grains formed under relatively low (5–15 GPa) shock pressures through a catalytic process in the presence of a Fe,Ni,Cr,S,P-rich melt. The highly shocked and fine-grained ureilites MS-MU 027 and MS-MU 045 have three different types of CPAs, namely a nanopolycrystalline assemblage of diamond and defect-rich diamond/lonsdaleite, disordered and distorted graphite, and polycrystalline diamond with abundant Fe-rich mineral inclusions. The CPAs that have only diamond and planar defect-rich diamond (e.g., MS-MU 027) most likely formed through martensitic transformation of graphite to diamond and lonsdaleite at >15 GPa and >2000 K. The assemblage of diamond, defect-rich diamond, and disordered and distorted graphite (e.g., MS-MU 045) formed by martensitic transformation of graphite to diamond and lonsdaleite, followed by back-transformation to disordered graphite. We did not find any conclusive evidence to support the formation of diamond grains under high static pressure.

¹Fabian Zahnow,¹Tido Stracke,¹Tommaso di Rocco,²Thilo Hasse,¹Andreas Pack
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14084]
¹Geowissenschaftliches Zentrum, Universität Göttingen, Göttingen, Germany
²Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
Published by arrangement with John Wiley & Sons

In this study, we present a method for high precision Δ′17O (Δ′17ORL = ln(δ17O + 1) – λRL ln(δ18O + 1)) analysis of small mass silicate and oxide materials. The analyses were conducted by laser fluorination in combination with gas chromatography and continuous flow isotope ratio monitoring gas spectrometry. We could analyze the oxygen isotope composition of samples down to 1 μg, which corresponded to about 13 nmol O2. The analytical error (we report the 1σ external reproducibility of a single analysis) in δ18O increases with decreasing sample sizes from ~0.2‰ for ~20 μg samples to ~0.9‰ for 1 μg samples. For Δ′17O, we achieved an external reproducibility of 0.04‰ for a sample mass range between 1 and 27 μg. The uncertainty in Δ′17O is smaller than the uncertainty in δ18O due to the correlated errors in δ17O and δ18O. We applied the method to urban micrometeorites, that is, small meteorites (<2 mm) that were sampled from a rooftop in Berlin, Germany. A total of 10 melted micrometeorites (S-type cosmic spherules, masses between 11 and 22 μg) were analyzed. The oxygen isotope compositions are comparable to that of modern Antarctic collections, indicating that the urban micrometeorites sample the same population. No indication for terrestrial weathering had been identified in the studied set of urban micrometeorites making them suitable materials for the study of micrometeorite origins.

¹S. Loehle,²J. Vaubaillon,³P. Matlovič,³J. Tóth
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115817]
¹High Enthalpy Flow Diagnostics Group, Institute of Space Systems, University of Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart, Germany
²IMCCE, Observatoire de Paris, PSL, 77 Av. Denfert Rochereau, Paris, 75014, France
³Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia
Copyright Elsevier

The paper reports the determination of luminous efficiency values from ground testing of a comprehensive set of meteorite samples. The ground testing data is translated with commonly used ground to flight extrapolation analogies from atmospheric entry maneuver’s engineering into values of a night observation. This results in a meteor at an altitude of 80 km with a flight speed of 11.7 km/s of a 34.8 mm diameter spherical meteoroid. A method is developed to determine the total luminous efficiency
in the bands U, B, V, R, and I from the radiance data and the measured mass loss. For the first time, a measurement of luminous efficiency became possible for known materials. The values itself are in the range of 0.01% to
1%, which is in the range of previous studies from meteor measurements.

¹A. Nakamura,¹M. Miyahara,^2,3H. Suga,⁴A. Yamaguchi,⁵D. Wakabayashi,⁵S. Yamashita,^5,6Y. Takeichi,¹K. Kukihara,²Y. Takahashi,⁷E. Ohtani
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2023JE007951]

¹Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, Japan
²Department of Earth and Planetary, Graduate School of Science, The University of Tokyo, Tokyo, Japan
³Japan Synchrotron Radiation Research Institute, Hyogo, Japan
⁴National Institute of Polar Research, Tokyo, Japan
⁵Institute of Materials Structure Science, High-Energy Accelerator Research Organization (KEK), Tsukuba, Japan
⁶School of Engineering, Osaka University, Osaka, Japan
⁷Department of Earth Sciences, Graduate School of Science, Tohoku University, Sendai, Japan
Published by arrangement with John Wiley & Sons

Alteration minerals in one of the Martian meteorite nakhlites, Yamato (Y) 000802, were studied to understand the alteration process and conditions. Mn-precipitates are discovered between altered plagioclase grains in Y 000802. Mn-precipitates consist of hausmannite (), manganite (γ-Mn³⁺OOH), rhodochrosite (Mn²⁺CO₃), and a trace amount of Mn⁴⁺O₂ mineral. Jarosite ) is also found. Mn²⁺ dissolved from olivine contributes to the formation of Mn-precipitates. A weakly acidic-neutral fluid containing a trace amount of  altered the olivine, and Mn²⁺ was dissolved into the fluid. The fluid also reacted with plagioclase and probably induced dealkalization of plagioclase, causing a local strong alkaline environment. Plagioclase was altered to ferroan saponite-nontronite + amorphous SiO₂ under alkaline conditions. Simultaneously, Mn^2+/3+-precipitates were formed from the Mn²⁺-containing fluid in the interstices between the altered plagioclase grains under the strong alkaline reducing environment. These alterations occurred in the deep part of the nakhlite body, where they are isolated from Martian subsurface water, including strong oxidants. The formation of Mn^2+/3+-precipitates may have been triggered by the melting of permafrost caused by an impact event around ∼633 Ma. Later, the nakhlite body was probably excavated by another impact, making it susceptible to water including strong oxidants. Pyrrhotite was dissolved and a highly acidic oxidizing fluid was formed, which would induce the formation of jarosite and the Mn⁴⁺O₂ mineral between ∼633 Ma and ∼11 Ma.

¹R. Ravichandran,¹S. Loehle,¹F. Hufgard,¹D. Leiser,⁴F. Zander,⁵L. Ferrière,²J. Vaubaillon,³P. Matlovič,³J. Tóth
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115818]
¹High Enthalpy Flow Diagnostics Group, Institute of Space Systems, University of Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart, Germany
²IMCCE, Observatoire de Paris, PSL, 77 Av. Denfert Rochereau, Paris, 75014, France
³Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia
⁴Institute of Advanced Engineering and Space Sciences, University of Southern Queensland, Toowoomba 4350, Queensland, Australia
⁵Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria
Copyright Elsevier

Optical emission spectra between 522-580 nm of ablating meteorites have been recorded at frame rates as high as 1 kHz for the first time during ground testing with simultaneous spatial and temporal resolution. A novel high frame rate emission spectroscopy arrangement has been developed and employed to diagnose the ablating meteorites in several experimental campaigns. In addition to the identification of species from emission lines detected, the resulting high-speed spectral data were used to study the temporal and spatial evolution of melting droplets and the associated spectral signatures. The time history of radiance from the atomic species emission was used to interpret the fragmentation behavior of various meteorites. Chelyabinsk meteorite exhibit almost constant radiance over time indicating steady droplet detachment whereas Ragland meteorite shows infrequent radiance peaks corresponding to random fragmentation/droplet detachment of varying sizes. A gradual rise in radiance history from iron meteorite Mount Joy shows that it takes finite time for melting and accumulation of droplets.

¹Vasilij G. Chiorny,^1,2Vasilij G. Shevchenko,^1,2Ivan G. Slyusarev,^1,2Olga I. Mikhalchenko,^1,3Yurij N. Krugly,³Dagmara Oszkiewicz
Planetary and Space Science (in Press) Open Access Link to Article [https://doi.org/10.1016/j.pss.2023.105779]
¹Institute of Astronomy of V.N. Karazin Kharkiv National University, Kharkiv 61022, Sumska Str. 35, Ukraine
²Department of Astronomy and Space Informatics of V.N. Karazin Kharkiv National University, Kharkiv 61022, 4 Svobody Sq., Ukraine
³Astronomical Observatory Institute, Faculty of Physics, A. Mickiewicz University, Słoneczna 36, 60-286 Poznan, Poland
Copyright Elsevier

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

^1,2V. Santiago Quinteros,³Thomas Dylan Mikesell,⁴Griffiths Luke,¹X. Jerves Alex
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115812]
¹Advanced Modelling, Norwegian Geotechnical Institute, Oslo, Norway
²Department of Civil Engineering and Energy Technology, Oslo Metropolitan University, Norway
³Remote Sensing and Geophysics, Norwegian Geotechnical Institute, Oslo, Norway
⁴Integrated Geotechnology, Norwegian Geotechnical Institute, Oslo, Norway
Copyright Elsevier

A comprehensive program of geotechnical index tests performed on two regolith simulants, namely LHS-1 and LMS-1, are presented and discussed in this study. The index tests included a 2D analysis of particles shapes and measurements of grain density, particle size distribution, plastic and liquid limit, thermal conductivity, and maximum and minimum dry density. The detailed testing methodologies are provided, and their results are discussed and compared with data available in the literature from similar tests on the same regolith simulants. Additionally, a thorough analysis of the data in contrast with data of lunar soils is presented. The observed spread on the index tests results is explained by the indiscriminate use of different procedures, regolith mass, and methodologies across different laboratories and highlight the importance and urgency for planetary scientist to agree on best practices in geotechnical testing of regolith and extra-terrestrial simulants.

¹Kierra Wilk,²Janice L. Bishop,³Catherine M. Weitz,⁴Mario Parente,⁴Arun M. Saranathan,^4,5Yuki Itoh,⁶Christoph Gross,⁷Jessica Flahaut,⁵Frank Seelos
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115800]
¹Brown University (Providence, RI)
²SETI Institute & NASA-Ames (Mountain View, CA)
³Planetary Science Institute (Tucson, AZ)
⁴University of Massachusetts at Amherst (Amherst, MA)
⁵Johns Hopkins University Applied Physics Lab (Laurel, MD)
⁶Free University of Berlin (Berlin, Germany)
⁷CRPG, CNRS/Université de Lorraine (Vandœuvre-lès-Nancy, France)
Copyright Elsevier

Intriguing outcrops in Ius Chasma provide a window into past aqueous processes in Valles Marineris, Mars. Hydrous sulfate minerals are abundant throughout this region, but one area in Ius Chasma includes phyllosilicates, opal, and additional materials with unusual spectral features. This study at Geryon Montes, an east-west horst that divides Ius Chasma into a northern and southern canyon, exploits recent advances in image calibration and feature extraction techniques for analysis of hyperspectral images acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Specifically, a unique spectral “doublet” feature with absorptions at 2.21–2.23 and 2.26–2.28 μm is isolated at the border of phyllosilicate-bearing and sulfate-bearing regions in Ius Chasma and surveyed to characterize outcrops that may represent a changing climate on Mars. We document and map three distinct forms of this “doublet” material in relation to phyllosilicates and opal. Analyses of compositional maps derived from CRISM overlain on High Resolution Stereo Camera (HRSC) and High Resolution Imaging Science Experiment (HiRISE) imagery has revealed the presence of these hydrated outcrops along the wall rocks below a breach in the Geryon Montes, bordering a canyon containing abundant hydrated sulfates. Our investigation supports formation of these unique alteration phases through acid alteration of ancient smectites in the wall rock as the sulfate brine overflowed the south canyon of Ius Chasma at the breach in Geryon Montes and penetrated the deeper northern canyon.