^1,2Schmitz, Birger,¹Terfelt, Fredrik
Estonian Journal of Earth Sciences 72, 94-97 Open Access Link to Article [DOI 10.3176/EARTH.2023.49]
¹Astrogeobiology Laboratory, Department of Physics, Lund University, Sweden
²Robert A. Pritzker Center for Meteoritics, Polar Studies, Field Museum of Natural History, Chicago, United States

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

¹Ke Wen,²Peng Yang,^1,3Mengqiang Zhu
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.08.028]
¹Department of Ecosystem Science and Management, University of Wyoming, Laramie, Wyoming 82071, United States
²Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
³Department of Geology, University of Maryland, College Park, Maryland 20742, United States
Copyright Elsevier

The occurrence of manganese (Mn) oxides on Mars is believed to be an indicator of an O2-rich paleoenvironment of Mars because Mn oxides often form through the oxidation of Mn(II) by O2 on the surface of Earth. An alternative formation pathway was recently proposed, in which Mn(II) is oxidized by bromate (BrO3-), a common oxidant in contemporary Martian regolith. However, the oxidation of Mn(II) by bromate in solution is kinetically controlled and slow unless using very high concentrations (100 mM) of reactants that may be irrelevant to the conditions of Mars. We conducted laboratory simulations to determine whether iron (Fe) oxides (hematite and goethite) and a phyllosilicate (montmorillonite), abundant minerals on the surface of Mars, could catalyze the oxidation of Mn(II) by bromate. Hematite and goethite, but not montmorillonite, dramatically accelerated the oxidation with a low concentration (1 mM) of Mn(II) and bromate under various solution conditions. The reaction system was autocatalytic with Fe oxides initiating the oxidation of Mn(II) at the early stage and the subsequent catalysis mainly provided by the Mn oxide products. In contrast to producing Mn(IV)O2 only during the homogeneous oxidation of Mn(II) by bromate in solutions, the heterogeneous mineral-surface catalyzed oxidation resulted in a mixture of Mn(III)OOH and Mn(IV)O2 phases. Mn(III)OOH was an intermediate product and can be further oxidized by bromate to Mn(IV)O2. The occurrence and accumulation of the intermediate product MnOOH can be attributed to its rapid formation due to surface-enhanced nucleation and growth on Fe oxide surfaces and to its higher resistance to oxidation by bromate than Mn(III) ions or clusters. Overall, mineral-surface catalyzed oxidation of Mn(II) by bromate is favorable from both thermodynamic and kinetic perspectives, and can be a major pathway for the occurrence of Mn oxides on Mars where microorganisms are lacking to catalyze the reaction. Our study further improves our understanding of the thermodynamic and kinetic controls on Mn(II) oxidation.

¹Xeynab Mouti Al-Hashimi,¹Jemma Davidson,¹Devin L. Schrader,²Emma S. Bullock
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14076]
¹Buseck Center for Meteorite Studies, School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
²Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC, USA
Published by arrangement with John Wiley & Sons

The Mighei-like carbonaceous (CM) chondrites, the most abundant carbonaceous chondrite group by number, further our understanding of processes that occurred in their formation region in the protoplanetary disk and in their parent body/bodies and provide analogs for understanding samples returned from carbonaceous asteroids. Chondrules in the CMs are commonly encircled by fine-grained rims (FGRs) whose origins are debated. We present the abundances, sizes, and petrographic observations of FGRs in six CMs that experienced varying intensities of parent body processing, including aqueous and thermal alteration. The samples studied here, in approximate order of increasing thermal alteration experienced, are Allan Hills 83100, Murchison, Meteorite Hills 01072, Elephant Moraine 96029, Yamato-793321, and Pecora Escarpment 91008. Based on observations of these CM chondrites, we recommend a new average apparent (2-D) chondrule diameter of 170 μm, which is smaller than previous estimates and overlaps with that of the Ornans-like carbonaceous (CO) chondrites. Thus, we suggest that chondrule diameters are not diagnostic for distinguishing between CM and CO chondrites. We also argue that chondrule foliation noted in ALH 83100, MET 01072, and Murchison resulted from multiple low-intensity impacts; that FGRs in CMs formed in the protoplanetary disk and were subsequently altered by both aqueous and thermal secondary alteration processes in their parent asteroid; and that the heat experienced by some CM chondrites may have originated from solar radiation of their source body/bodies during close solar passage as evidenced by the presence of evolved desiccation cracks in FGRs that formed by recurrent wetting and desiccation cycles.

¹M. V., ²G. Varga, Z. Dankházi,¹A. V. Chukin,³I. Felner,²E. Kuzmann,¹V. I. Grokhovsky,²Z. Homonnay,¹M. I. Oshtrakh
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14070]
¹Institute of Physics and Technology, Ural Federal University, Ekaterinburg, Russian Federation
²Department of Materials Physics, Eötvös Loránd University, Budapest, Hungary
³Racah Institute of Physics, The Hebrew University, Jerusalem, Israel
⁴Laboratory of Nuclear Chemistry, Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary
Published by arrangement with John Wiley & Sons

A fragment of Mundrabilla IAB-ung iron meteorite was analyzed using optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), magnetization measurements, and Mössbauer spectroscopy. The polished section of meteorite fragment characterization by optical microscopy and SEM shows the presence of the γ-Fe(Ni, Co) phase lamellae, plessite structures and schreibersite inclusions in the α-Fe(Ni, Co) phase. EDS indicates variations in the Ni concentrations in the following ranges: (i) ∼6.3–6.5 atom% in the α-Fe(Ni, Co) phase and (ii) ∼22 to ∼45 atom% in the γ-Fe(Ni, Co) phase lamellae including the range of ∼29–33 atom% of Ni leading to the paramagnetic state of the γ-Fe(Ni, Co) phase. Schreibersite inclusions contain ∼23 atom% of P, ∼33 atom% of Fe, ∼43 atom% of Ni, and ∼0.7 atom% of Co. Plessite structure contains the average Ni concentration of ∼17 atom% while detailed EDS analysis shows: (i) the lowest Ni concentrations of ∼5 to ∼8 atom%, (ii) the intermediate Ni concentrations of ∼9 to ∼19 atom%, and (iii) the highest Ni concentration up ∼38 atom% (some individual micro-grains demonstrate up to ∼47 and ∼59 atom% of Ni) that may indicate the presence of the (i) α-Fe(Ni, Co), (ii) α₂-Fe(Ni, Co), and (iii) γ-Fe(Ni, Co) phases. These may be a result of the γ-phase decomposition with mechanism γ → α + α₂ + γ that indicates a slow cooling rate for Mundrabilla IAB-ung iron meteorite. The presence of ∼98.6 wt% of the α-Fe(Ni, Co) phase and ∼1.4 wt% of the γ-Fe(Ni, Co) phase is found by XRD while schreibersite is not detected. Magnetization measurements show the saturation magnetization moment of Mundrabilla IAB-ung of 188(2) emu g⁻¹ indicating a low average Ni concentration in Fe-Ni-Co alloy. Mössbauer spectrum of the bulk Mundrabilla powder demonstrates five magnetic sextets related to the ferromagnetic α₂-Fe(Ni, Co), α-Fe(Ni, Co), and γ-Fe(Ni, Co) phases and one singlet associated with the paramagnetic γ-Fe(Ni, Co) phase, however, there are no spectral components corresponding to schreibersite. Basing on relatively larger and smaller values of the magnetic hyperfine field, two magnetic sextets associated with γ-Fe(Ni, Co) phase can be related to the disordered and more ordered γ-phases. The iron fractions in the detected phases can be roughly estimated as follows: (i) ∼17.6% in the α₂-Fe(Ni, Co) phase, (ii) ∼68.5% in the α-Fe(Ni, Co) phase, (iii) ∼11.5% in the disordered γ-Fe(Ni, Co) phase, (iv) ∼2.0% in the more ordered γ-Fe(Ni, Co) phase, and (v) ∼0.4% in the paramagnetic γ-Fe(Ni, Co) phase.

^1,2PengYue Wang,³Edward Cloutis,¹XiaoPing Zhang,^1,4Ye Su,^1,5YunZhao Wu
Meteoritics & Planetary Science(in Press) Link to Article [https://doi.org/10.1111/maps.14077]
¹State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, China
²Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China
³Department of Geography, University of Winnipeg, Winnipeg, Canada
⁴Center for Excellence in Comparative Planetology, Chinese Academy of Science, Hefei, China
⁵Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, Chi
Published by arrangement with John Wiley & Sons

The impact threat of some near-Earth Asteroids (NEAs) drives our need to understand their mineral compositions. Quantitative mineral abundances based on reflectance spectroscopy are of great significance for studying the compositions of NEAs. In this study, we constrained the surface mineralogy of (99942) Apophis based on multiple diagnostic spectral parameters. The influence of non-mineral component factors (e.g., space weathering, phase angle, and surface temperature) on diagnostic spectral parameters was evaluated. We established the connection between Apophis and corresponding meteorite analog. Our results show that the abundances of olivine and pyroxene on the surface of Apophis are 53.4 ± 6 wt% and 35.6 ± 2 wt%, respectively. The 1 μm band width is basically unaffected by phase-angle changes and is less affected by temperature variations. Low temperature has more obvious effects on the 1.25/1 μm band depth ratio (BDR 1.25) based on the present data. When the phase angle ranges from 60° to 120°, the BDR 1.25 changes significantly with the increase or decrease of phase angle. In terms of spectral characteristics, the best meteorite analog of Apophis is LL chondrite, confirming earlier interpretations. Mineral analyses based on multiple diagnostic spectral parameters provide more consistent results. Knowledge of the surface compositions of Apophis can also inform optimum or possible defense strategies for it and other NEAs.

¹Juraj Tóth et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115791]
¹Faculty of Mathematics, Physics and Informatics, Comenius University Bratislava, Mlynska dolina, Bratislava, 84248, Slovakia
Copyright : Elsevier

We provide an overview of the MetSpec project, which aims to connect meteorite ablation laboratory experiments with meteor spectral observations in the atmosphere aiming at the development of a methodology to identify incoming planetary material distribution into the Earth’s atmosphere. We have selected 28 meteorites of different types to represent known planetary material compositions coming from asteroids, Vesta, Mars and the Moon. Some samples have been tested twice which resulted in overall 31 experiments. Three distinct test campaigns were realized in 2020, 2021 and 2022 with the High Enthalpy Flow Diagnostics Group in the Plasma Wind Tunnel PWK1 where they have developed a unique testing scenario. During the last and most elaborated campaign, 16 cameras observed the artificial meteors in the laboratory. Besides videos and online live streaming, instruments included several spectrometers, and optical and imaging instruments covering UV, visible and IR spectral range. This special collection in Icarus collects the resulting output from the different instruments and results. This overview article provides an introduction and summarizes the main findings of the experimental campaigns.

¹Edward R. D. Scott,²Ian S. Sanders,³Erik Asphaug,²Emma L. Tomlinson
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14069]
¹Hawai’i Institute of Geophysics and Planetology, University of Hawai’i at Mānoa, Honolulu, Hawai’i, USA
²Department of Geology, Trinity College Dublin, Dublin 2, Ireland
³Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA
Published by arrangement with John Wiley & Sons

A unique 2 mm-wide clast of fine-grained garnet–omphacite peridotite with chondritic chemistry was reported from the CR2 chondrite Northwest Africa 801 by Hiyagon et al. (2016, Geochimica et Cosmochimica Acta, 186, 32–48). Those authors described the clast as eclogitic and inferred from its mineral compositions that the rock formed quickly, during perhaps 100–1000 years of burial, deep within a Moon-sized body at about 3 GPa (30 kbar) pressure and 1000°C. Such conditions are unprecedented among meteorites and invite scrutiny. Here, we discuss the clast and its origin. The inferred conditions appear justified, but the published idea of burial during a protoplanetary merger and, soon after, exhumation in a violent collision seems improbable and contrary to the clast’s low shock levels. We find that exhumation is better explained by pull-apart of a projectile in a low velocity hit-and-run collision. We try inconclusively to explain near-simultaneous burial and exhumation in a hit-and-run return scenario. Taking a different approach, and to conclude, we speculate that an approximately lunar-mass body was molten beneath a thin dense chondritic crust, of which fragments foundered and sank deep into the magma ocean as an ongoing process. Fragments that were changing to garnet–omphacite peridotite were exhumed when the molten body was pulled apart in a hit-and-run collision with a larger body.

¹Atsushi Takenouchi,²Akira Yamaguchi,³Takashi Mikouchi,⁴Richard Greenwood,⁵Sojiro Yamazaki
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14073]
¹The Kyoto University Museum, Kyoto University, Kyoto, Japan
²National Institute of Polar Research, Tokyo, Japan
³The University Museum, The University of Tokyo, Tokyo, Japan
⁴Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes, UK
⁵Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan
Published by arrangement with John Wiley & Sons

Asuka (A) 12325 is the first poikilitic shergottite having a depleted pattern in light rare earth elements (REE). Compared with known poikilitic shergottites, A 12325 has smaller but more abundant pyroxene oikocrysts with remarkable Fe-rich pigeonite rims, indicating that A 12325 cooled relatively faster at a shallower part of the crust. The redox condition (logfO2 = IW + 0.6-IW + 1.7) and Fe-rich chemical compositions of each mineral in A 12325 are close to enriched shergottites. The intermediate shergottites could not form by a simple mixing between parent magmas of A 12325 and enriched shergottites. Although A 12325 contains various high-pressure minerals such as majorite and ringwoodite, plagioclase is only partly maskelynitized. Therefore, the maximum shock pressure may be within 17–22 GPa. Thermal conduction and ringwoodite growth calculation around a shock vein revealed that the shock dwell time of A 12325 is at least 40 ms. The weaker shock pressure and longer shock dwell time in A 12325 may be attained by an impact event similar to those of nakhlites and Northwest Africa (NWA) 8159. Such a weak shock ejection event may be as common on Mars as a severe shock event recorded in shergottites. Alteration of sulfide observed in A 12325 may imply the presence of magmatic fluid in its reservoir on Mars. A 12325 expands a chemical variety of Martian rocks and has a unique shock history among poikilitic shergottites while A 12325 also implies that poikilitic shergottites are common rocks on Mars regardless of their sources.

¹Heng-Ci Tian,¹Wei Yang,¹Di Zhang,^1,3Huijuan Zhang,²Lihui Jia,²Shitou Wu,¹Yangting Lin,²Xianhua Li,²Fuyuan Wu
American Mineralogist 108, 1669-1677 Link to Article [http://www.minsocam.org/msa/ammin/toc/2023/Abstracts/AM108P1669.pdf]
¹Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
²State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
³School of Earth Sciences, East China University of Technology, Nanchang 330013, Jiangxi, China
Copyright: The Mineralogical Society of America

This study focuses on using the chemical compositions of plagioclase to further investigate the
petrogenesis of Chang’E-5 young mare basalts and constrain its parental melt composition. Together
with previously published data, our results show that the plagioclase in mare basalts overall displays
large variations in major and trace element concentrations. Inversion of the plagioclase data indicates
that the melt compositions parental to Chang’E-5 basalts have high rare earth elements (REE) concentrations similar to the high-K KREEP rocks (potassium, rare earth elements, and phosphorus). Such a signature is unlikely to result from the assimilation of KREEP components, because the estimated
melt Sr shows positive correlations with other trace elements (e.g., Ba, La), which are far from the
KREEP end-member. Instead, the nearly parallel REE distributions and a high degree of trace element
enrichment in plagioclase indicate an extensive fractional crystallization process. Furthermore, the
estimated melt REE concentrations from plagioclase are slightly higher than those from clinopyroxene,
consistent with its relatively later crystallization. Using the Ti partition coefficient between plagioclase
and melt, we estimated the parental melt TiO2 content from the earliest crystallized plagioclase to be
~3.3 ± 0.4 wt%, thus providing robust evidence for a low-Ti and non-KREEP origin for the Chang’E-5
young basalts in the Procellarum KREEP terrane.

^1,2Xiaojing Lai,³Feng Zhu,²Dongzhou Zhang,⁴Sergey Tkachev,⁴Vitali B. Prakapenka,²Keng-Hsien Chao,²Bin Chen
American Mineralogist 108, 1530-1537 Link to Article [http://www.minsocam.org/msa/ammin/toc/2023/Abstracts/AM108P1530.pdf]
¹Gemmological Institute, State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, Hubei, 430074, China 
²Hawaii Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, Hawaii 96822, U.S.A. 
³School of Earth Sciences, State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, Hubei, 430074, China 
⁴Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, U.S.A.
Copyright: The Mineralogical Society of America

Ice-VII is a high-pressure polymorph of H2O ice and an important mineral widely present in many
planetary environments, such as in the interiors of large icy planetary bodies, within some cold subducted
slabs, and in diamonds of deep origin as mineral inclusions. However, its stability at high pressures
and high temperatures and thermoelastic properties are still under debate. In this study, we synthesized
ice-VII single crystals in externally heated diamond-anvil cells and conducted single-crystal X-ray
diffraction experiments up to 78 GPa and 1000 K to revisit the high-pressure and high-temperature
phase stability and thermoelastic properties of ice-VII. No obvious unit-cell volume discontinuity or
strain anomaly of the high-pressure ice was observed up to the highest achieved pressures and temperatures. The volume-pressure-temperature data were fitted to a high-temperature Birch-Murnaghan
equation of state formalism, yielding bulk modulus KT0 = 21.0(4) GPa, its first pressure derivative KT′0
= 4.45(6), dK/dT = –0.009(4) GPa/K, and thermal expansion relation αT = 15(5) × 10–5 + 15(8) × 10–8
× (T – 300) K–1. The determined phase stability and thermoelastic properties of ice-VII can be used to
model the inner structure of icy cosmic bodies. Combined with the thermoelastic properties of diamonds,
we can reconstruct the isomeke P-T paths of ice-VII inclusions in diamond from depth, offering clues
on the water-rich regions in Earth’s deep mantle and the formation environments of those diamonds.