^1,2Erbin Shi,²Alian Wang,³Huafang Li,²Ryan Ogliore,¹Zongcheng Lin
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2021JE007108]
¹School of Space Science and Physics, Shandong Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, Shandong, 264209 China
²Department of Earth & Planetary Sciences and McDonnell Center for the Space Sciences Washington University in St. Louis, MO, 63130 USA
³The Institute of Materials Science & Engineering, Washington University in St. Louis, MO, 63130 USA
Published by arrangement with John Wiley & Sons

Ordinary γ-CaSO₄ is a metastable calcium sulfate, while γ-CaSO₄ from the hyperarid region on Earth and from Mars has been found with abnormally high stability. In this study, we used multiple microanalyses to characterize the chemical and structural properties of two such γ-CaSO₄: one from Atacama soil (#10-d30) and the other from Martian meteorite MIL03346,168. Silicon was determined to be quasi-homogeneously distributed in Atacama γ-CaSO₄, while both silicon and phosphorus were detected in Martian γ-CaSO₄. We found the abnormally high stability of those γ-CaSO₄ from hyperarid environments was due to the chemical impurities which filled their structural tunnels and blocked the entrance of atmospheric H₂O, with non-detectable structural distortion. We propose that the γ-CaSO₄ with Si or Si and P impurities could have igneous origin or evaporative origin. Due to the extreme similarity in the structures of bassanite and γ-CaSO₄, their XRD patterns are almost non-distinguishable; thus some martian “bassanite” minerals identified by Curiosity’s CheMin instrument at Gale crater can actually be γ-CaSO₄. The structural tunnels in γ-CaSO₄ would allow ions and ionic groups to fill, thus providing meaningful insights about the geological and geochemical processes experienced by it during the formation and transformation. The Raman spectrometer carried by the Perseverance and by ExoMars rovers will help the selection of samples enriched in γ-CaSO₄ at Jezero Crater and Oxia Planum, which should be sampled for in-depth analysis on Mars and back to Earth.

¹Erwin Dehouck et al. (>10)
Journal of Geophysical Research, Planets (in Press) Open Access Link to Article [https://doi.org/10.1029/2021JE007103]
¹Univ Lyon, UCBL, ENSL, UJM, CNRS, LGL-TPE, F, 69622 Villeurbanne, France
Published by arrangement with John Wiley & Sons

Glen Torridon is a topographic trough located on the slope of Aeolis Mons, Gale crater, Mars. It corresponds to what was previously referred to as the “clay-bearing unit”, due to the relatively strong spectral signatures of clay minerals (mainly ferric smectites) detected from orbit. Starting in January 2019, the Curiosity rover explored Glen Torridon for more than 700 sols (Martian days). The objectives of this campaign included acquiring a detailed understanding of the geologic context in which the clay minerals were formed, and determining the intensity of aqueous alteration experienced by the sediments. Here, we present the major-element geochemistry of the bedrock as analyzed by the ChemCam instrument. Our results reveal that the two main types of bedrock exposures identified in the lower part of Glen Torridon are associated with distinct chemical compositions (K-rich and Mg-rich), for which we are able to propose mineralogical interpretations. Moreover, the topmost stratigraphic member exposed in the region displays a stronger diagenetic overprint, especially at two locations close to the unconformable contact with the overlying Stimson formation, where the bedrock composition significantly deviates from the rest of Glen Torridon. Overall, the values of the Chemical Index of Alteration determined with ChemCam are elevated by Martian standards, suggesting the formation of clay minerals through open-system weathering. However, there is no indication that the alteration was stronger than in some terrains previously visited by Curiosity, which in turn implies that the enhanced orbital signatures are mostly controlled by non-compositional factors.

¹Eric T. Parker,²Queenie H. S. Chan,³Daniel P. Glavin,⁴Jason P. Dworkin
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13794]
¹Astrobiology Analytical Laboratory, Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, 20771 USA
²Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX UK
³School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA UK
Published by arrangement with John Wiley & Sons

Amino acid abundances in acid-hydrolyzed hot water extracts of gold foils containing five Category 3 (carbon-rich) Hayabusa particles were studied using liquid chromatography with tandem fluorescence and accurate mass detection. Initial particle analyses using field emission scanning electron microscopy with energy-dispersive X-ray spectrometry indicated that the particles were composed mainly of carbon. Prior to amino acid analysis, infrared and Raman microspectroscopy showed some grains possessed primitive organic carbon. Although trace terrestrial contamination, namely l-protein amino acids, was observed in all Hayabusa extracts, several terrestrially uncommon non-protein amino acids were also identified. Some Hayabusa particles contained racemic (d≈l) mixtures of the non-protein amino acids β-aminoisobutyric acid (β-AIB) and β-amino-n-butyric acid (β-ABA) at low abundances ranging from 0.09 to 0.31 nmol g⁻¹. Larger abundances of the non-protein amino acid β-alanine (9.2 nmol g⁻¹, ≈4.5 times greater than background levels) were measured in an extract of three Hayabusa particles. This β-alanine abundance was ≈6 times higher than that measured in an extract of a CM2 Murchison grain processed in parallel. The comparatively high β-alanine abundance is surprising as asteroid Itokawa is similar to amino acid-poor LL ordinary chondrites. Elevated β-alanine abundances and racemic β-AIB and β-ABA in Hayabusa grains suggested these compounds have non-biological and plausibly non-terrestrial origins. These results are the first evidence of plausibly extraterrestrial amino acids in asteroid material from a sample-return mission and demonstrate the capabilities of the analytical protocols used to study asteroid Ryugu and Bennu samples returned by the JAXA Hayabusa2 and NASA OSIRIS-REx missions, respectively.

^1,2Liam S.Morrissey,³D.Pratt,¹W.M.Farrell,¹O.J.Tucker,³S.Nakhla,¹R.M.Killen
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.114979]
¹NASA Goddard Space Flight Center, 20771 Greenbelt, MD, United States
²Catholic University /CRESST II, Washington, DC 20005, United States
³Department of Mechanical Engineering, Memorial University of Newfoundland, A1C 5S7 St. John’s, Newfoundland & Labrador, Canada
Copyright Elsevier

We use molecular dynamics (MD) simulations to better explain the movement of atomic hydrogen in amorphous silica and quantify the planetary science implications of these findings. Previous MD simulations had a large range of predicted values and did not agree well with experiment. Our simulations sample atomic motion for a longer duration and consider a wider range of temperatures than previous simulations. In contrast to constant atomic motion, the hydrogen atoms were shown to undergo random intermittent jumps from one oxygen atom to another, the number of which increase with temperature. Predicted diffusion coefficients had a better agreement to experimental values than previous MD simulations, suggesting the importance of longer simulation durations for better statistics. The low activation energy and jumps observed at lunar temperatures do not support the theory of diurnal variations in OH content for an undamaged amorphous silica surface. Instead, we conclude that energetic solar wind impacts can induce two competing atomic hydrogen motion processes in the exposed surface: A prompt effect that induces jumps in the temperature spike volume, but also a long-term effect of damage in the structure that traps atomic hydrogen. We then use SDTrimSP to quantify the damage created during exposure and MD to demonstrate the H retention and trapping near these defects. Damage was shown to be dependent on impact energy, with defects easily retaining implanted hydrogen. MD results like those presented herein on unweathered surfaces are therefore most relevant to magnetic anomalies. As a result, we demonstrate the importance of lunar volatile models to account for the damage state of the substrate when modelling hydrogen diffusion, retention, and subsequent OH/water production.

¹Hannah L.Bercovici,¹Linda T.Elkins-Tanton,¹Joseph G.O’Rourke,²Laura Schaefer
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.114976]
¹School of Earth and Space Exploration, ASU, 781 E Terrace Mall Tempe, AZ 85287, USA
²Stanford University, 450 Serra Mall, Stanford, CA 94305, USA
Copyright Elsevier

This study explores the compositions and sizes of metallic cores that result from planetesimals forming from a range of chondritic bulk compositions. Our models examine the influence of starting bulk composition on core size and composition, how oxygen fugacity (fO2), temperature, pressure, and bulk composition affect sulfur partitioning between the core and silicate mantle of planetesimals, and the formation and fate of immiscible sulfur-rich liquid during core solidification. We apply experimentally-derived equations for the sulfur distribution coefficient to the bulk compositions of ordinary chondrites (H,L,LL) and carbonaceous chondrites (CM, CI, CO, CK, CV) under conditions appropriate for melting planetesimals.

The sulfur content of all modeled cores is above 6 wt% S, which is greater than the amount of sulfur needed to form an immiscible sulfide liquid in the presence of other light elements (e.g., C, Si, and/or P). We concluded that early planetesimal cores likely formed either an immiscible sulfide liquid, a eutectic sulfide liquid, or most surprisingly, were composed of mostly monosulfide solid solution, [(Fe, Ni)1-xS].

¹Hiroshi Kimura,²Johannes Markkanen,³Ludmilla Kolokolova,⁴Martin Hilchenbach,¹Koji Wada,¹Yasumasa Kanada,¹Takafumi Matsuia
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.114964]
¹Planetary Exploration Research Center (PERC), Chiba Institute of Technology, Tsudanuma 2-17-1, Narashino, Chiba 275-0016, Japan
²Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
³ Planetary Data System Group, Department of Astronomy, Rm. 2337, Computer and Space Science Bldg., University of Maryland, College Park, MD, 20742, USA
⁴ Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077, Göttingen, Germany
Copyright Elsevier

A well-established constraint on the size of non-porous olivine grains or the porosity of aggregates consisting of small olivine grains from prominent narrow peaks in thermal infrared spectra characteristic of crystalline silicates is reexamined. To thoroughly investigate thermal infrared peaks, we make theoretical argument for the absorption and scattering of light by non-porous, non-spherical olivine particles, which is followed by numerical verification. Our study provides perfectly rational explanations of the physics behind the small-particle effect of emission peaks in the framework of classical electrodynamics and convincing evidence of small-particle’s emission peaks in the literature. While resonant absorption excited by surface roughness on the order of submicrometer scales can be identified even for non-porous olivine particles with a radius of m, it makes only a negligible contribution to thermal infrared spectra of the particles. In contrast, the porosity of non-spherical particles has a significant impact on the strength and wavelength of the peaks, while the resonant absorption excited by an ensemble of small grains takes place at a wavelength different than one expects for surface roughness. We finally reaffirm that twin peaks of olivine in thermal infrared spectra of dust particles in astronomical environments are the intrinsic diagnostic characters of submicrometer-sized small grains and their aggregate particles in fluffy and porous configurations.

¹Marina A. Ivanova,¹Cyril A. Lorenz,²Munir Humayun,²Shuying Yang,³Chi Ma,¹Svetlana N. Teplyakova,⁴Ian A. Franchi,¹Alexander V. Korochantsev
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13786]
¹Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow, 119991 Russia
²National High Magnetic Field Laboratory and Department of Earth, Ocean & Atmospheric Science, Florida State University, Tallahassee, 1800 E. Paul Dirac Drive, Tallahassee, Florida, 32310 USA
³Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, 91125 USA
⁴Planetary and Space Sciences Research Institute, Open University, Milton Keynes, MK7 6AA UK
Published by arrangement with John Wiley & Sons

The new metal-enriched anomalous chondrite Sierra Gorda 013 (SG 013) contains two different lithologies. Lithology 1 (L1) is represented by anomalous CBa-like chondrite material containing ~80 vol% of Fe,Ni-metal particles and globules up to 6 mm in size; chondrules and clasts of types POP, BO, and SO (up to 5 mm in diameter); rare sulfides; and shock melted silicate–metal areas. It does not contain any fine-grained matrix. Several chondrules contain chromite–pyroxene symplectites. Lithology 2 (L2) has a recrystallized texture with evenly distributed olivine, pyroxene and plagioclase. L2 does not have any chondrules or sulfides, and contains less Fe,Ni- metal (~25 vol%) than L1. Both lithologies contain reduced olivine (Fa2–4) and pyroxene (Fs3.5), similar to CBa chondrites. Similar to CBa, there is no Ni-Co correlation in the SG 013 metal. Rare sulfides in L1 are enriched in V. Chromite was observed in both lithologies. Oxygen isotope compositions of both lithologies are different but in the range of CBa chondrites. Bulk major and trace element geochemistry of nonporphyritic chondrules and bulk siderophile compositions in metal globules of L1 indicate elemental fractionation during formation of metallic and silicate objects with records of the evaporation process: depletion in moderate and volatile elements with the exception of Cr. Bulk geochemistry of porphyritic chondrules of L1 and the silicate portion of L2 is similar and also indicates evaporation processes. The rare Earth element (REE) distribution of L1 chondrules records a very fractionated signature corresponding to possible differentiated precursor material, while the REE pattern of L2 is primitive chondritic. The formation of SG 013 could be explained by collisions of planetesimals producing an impact plume, the precursor material of which could be chondritic and possibly differentiated. Both lithologies were affected by secondary processes: L1 preserved the traces of shock events and partial melting resulting in formation of symplectites in chondrules, melt pockets, and metal–silicate melt between the metal globules; L2 was affected by shock thermal metamorphism (up to 900 °C) resulting in recrystallization.

¹Romain Tartèse,¹Stanley Endley,¹Katherine H. Joy
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13798]
¹Department of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL UK
Published by arrangement with John Wiley & Sons

Impact crater central peaks and peak ring complexes are important exploration targets for future missions to other planetary bodies, because they provide access to material uplifted from lower crustal levels. Material exposed there could also provide chronological constraints on crater formation events. Therefore, it is essential to understand if uplifted peak material preserves the chronological records of igneous and metamorphic protolith crustal rocks, or if such records are reset during impact events. To investigate this issue, we collected shocked gneiss and granite samples from uplifted crystalline basement megablocks in the 24 km diameter Ries impact crater in Germany, which is dated at ~14.8 Ma. Petrographic observations, electron beam imaging, and Raman spectroscopy suggest that these samples record the peak pressures of ~10–15 GPa. In situ U-Pb dating shows that monazite U-Pb systematics have not been affected by the Ries impact, as gneisses and granites yielded monazite U-Pb dates of ~370 and 330 Ma, consistent with known Variscan metamorphic and magmatic events. The U-Pb systematics of some zircon grains yielded U-Pb dates of approximately 5–10 Ma, which is younger than the age of the Ries impact event. These young dates correspond to U-rich metamict domains and may reflect recent Pb loss and/or U-gain during postimpact hydrothermal alteration or weathering. These observations indicate that dating uplifted crystalline material in impact craters on other bodies might provide useful petrological and chronological constraints on the underlying target rocks rather than directly dating impact events, for which sampling impact melt and impact melt-bearing lithologies should remain the primary target.

^1,2Yuan Li,^1,2Yan-Xiang,^1,2LiZhengXu
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2022.02.027]
¹State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
²CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
Copyright Elsevier

Geochemical and cosmochemical reservoirs show Cu/Ag variations from 500 to 40000. To understand magmatic Cu–Ag fractionation and origins of such large Cu/Ag variations, we have measured the partition coefficients of Cu and Ag between minerals and silicate melts () relevant for partial melting of the silicate mantles of Earth, Mars, and the Moon. The experiments were conducted at 1–3 GPa, 1300–1600 °C, and oxygen fugacity ∼2–5 log units below the FMQ buffer. The results show that are 0.034–0.109 for olivine, 0.011–0.044 for orthopyroxene, and 0.046–0.092 for clinopyroxene; are 0.003–0.012 for orthopyroxene and 0.037–0.093 for clinopyroxene. These values increase mainly with increasing pressure and are oxygen fugacity-independent. are 0.0005–0.0017 for olivine, which do not show measurable dependence on P–T, oxygen fugacity, or silicate composition. One pair of values are 0.0037 and 0.0004 for garnet, respectively; 0.15 and 0.005 for spinel, respectively. These results indicate that Ag is more incompatible than Cu in all mantle minerals. Our combined with previous sulfide–silicate melt partition coefficients of Cu and Ag imply that although sulfides host large fractions of planetary mantle Cu and Ag, silicate minerals can be also important Cu and Ag reservoirs, particularly when sulfides occur as monosulfide solid solutions. The application of our to various melting models demonstrates that Cu–Ag fractionation occurs during partial melting of the silicate mantles of Earth, Mars, and the Moon; however, the modeled Cu/Ag ratios in basalts agree with their mantle source Cu/Ag ratios within 50% relative. Therefore, the superchondritic but similar Cu/Ag ratios of ∼3000–4000 in mid-ocean ridge basalts, arc basalts, mantle plume-related oceanic island basalts and plateau basalts, and the bulk silicate Earth (BSE) reflect homogeneous distribution of Cu/Ag in Earth’s mantle and limited Cu–Ag fractionation during slab dehydration/melting in subduction zones. However, components with chondritic Cu/Ag ratios (∼600–2300) may exist in the mantle sources of Hawaii oceanic island lavas. The Cu/Ag ratios (∼500–1100) in the Martian basalts and bulk silicate Mars (BSMars) are chondritic, but the Cu/Ag ratio (∼15000–40000) in the bulk silicate Moon (BSMoon) is strongly superchondritic. Such largely different Cu/Ag ratios in different planetary reservoirs cannot be explained by magmatic Cu–Ag fractionation, solar nebular process, or core-formation process. We propose that different degrees of planetary melting and evaporation provide a solution because Ag is more volatile than Cu during silicate melt evaporation. The chondritic Cu/Ag ratios in the BSMars could be explained by limited evaporation of planetesimals that delivered Mars’ moderately volatile elements, and the superchondritic Cu/Ag ratios in the BSE may be due to Earth’s accretion of planetesimals with partial evaporative loss of Cu and Ag. However, high degrees of evaporative Cu and Ag loss during the Moon-formation are required to explain the strongly superchondritic Cu/Ag ratios in the BSMoon. Accordingly, Cu/Ag ratios in the bulk silicate planets may provide new insights into the nature of their building blocks.

¹Anna Barbaro,^2,3Fabrizio Nestola,⁴Lidia Pittarello,⁴Ludovic Ferrière,⁵Mara Murri,⁶Konstantin D. Litasov,²Oliver Christ,¹Matteo Alvaro,¹M. Chiara Domeneghetti
American Mineralogist 107, 377-384 Link to Article [DOI: https://doi.org/10.2138/am-2021-7856]
¹Department of Earth and Environmental Sciences, University of Pavia, Via A. Ferrata 1, I-27100 Pavia, Italy
²Department of Geosciences, University of Padova, Via Gradenigo 6, 35131 Padova, Italy
³Geoscience Institute, Goethe-University Frankfurt, Altenhöferallee 1, 60323 Frankfurt, Germany
⁴Department of Mineralogy and Petrography, Natural History Museum, Burgring 7, 1010 Vienna, Austria
⁵Department of Earth and Environmental Sciences, University of Milano-Bicocca, I-20126 Milano, Italy
⁶Vereshchagin Institute for High Pressure Physics RAS, Troitsk, Moscow, 108840 Russia
Copyright: The Mineralogical Society of America

The formation and shock history of ureilite meteorites, a relatively abundant type of primitive
achondrites, has been debated for decades. For this purpose, the characterization of carbon phases
can provide further information on diamond and graphite formation in ureilites, shedding light on the
origin and history of this meteorite group. In this work, we present X‑ray diffraction and micro‑Raman
spectroscopy analyses performed on diamond and graphite occurring in the ureilite Yamato 74123
(Y-74123). The results show that nano- and microdiamonds coexist with nanographite aggregates.
This, together with the shock-deformation features observed in olivine, such as mosaicism and planar
fractures, suggest that diamond grains formed by a shock event (≥15 GPa) on the ureilitic parent
body (UPB). Our results on Y-74123 are consistent with those obtained on the NWA 7983 ureilite and
further support the hypothesis that the simultaneous formation of nano- and microdiamonds with the
assistance of a Fe-Ni melt catalysis may be related to the heterogeneous propagation and local scat –
tering of the shock wave. Graphite geothermometry revealed an average recorded temperature (Tmax)
of 1314 °C (±120 °C) in agreement with previously estimated crystallization temperatures reported
for graphite in Almahata Sitta ureilite.