¹Sammy Griffin,²Arya Udry,^1,3,4Luke Daly,^5,6Lucy Victoria Forman,¹Martin R. Lee,⁷Benjamin E. Cohen
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13934]
¹School of Geographical and Earth Sciences, University of Glasgow, Glasgow, G12 8QQ UK
²Department of Geoscience, University of Nevada Las Vegas, Las Vegas, Nevada, 89154 USA
³Australian Centre for Microscopy and Microanalysis, The University of Sydney, New South Wales, 2006 Australia
⁴Department of Materials, University of Oxford, Oxford, OX1 3PH UK
⁵Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Western Australia, 6845 Perth, Australia
⁶Department of Earth and Planetary Sciences, Western Australia Museum, Western Australia, 6986 Perth, Australia
⁷School of GeoSciences, University of Edinburgh, Edinburgh, EH9 3FE UK
Published by arrangement with John Wiley & Sons

To better understand volcanism on planetary bodies other than the Earth, the quantification of physical processes is needed. Here, the petrogenesis of the achondrite Martian Yamato (Y) nakhlites (Y 000593, Y 000749, and Y 000802) is reinvestigated via quantitative analysis of augite (high-Ca clinopyroxene) phenocrysts: crystal size distribution (CSD), spatial distribution patterns (SDP), and electron backscatter diffraction (EBSD). Results from CSD and EBSD quantitative data sets show augite to have continuous uninterrupted growth resulting in calculated minimum magma chamber residence times of either 88–117 ± 6 yr or 9–12 yr. All samples exhibit low-intensity S-LS type crystallographic preferred orientation. Directional strain is observed across all samples with intracrystalline misorientation patterns indicative of (100)[001]:(001)[100] (Y 000593 and Y 000802) and {110}<001>or {110}1/2<110> (Y 000749) slip systems. SDP results indicate phenocryst-bearing crystal-clustered rock signatures. Combined findings from this work show that the Yamato nakhlites formed on Mars as individual low-viscosity lava flows or sills. This study shows that through combining these different quantitative techniques over multiple samples, one can more effectively compare and interpret resulting data to gain a more robust, geologically contextualized petrogenetic understanding of the rock suite being studied. The techniques used in this study should be equally applicable to igneous achondrites from other parent bodies.

¹Kevin Righter,²Ryan S. Jakubek,¹Marc D. Fries,³John Schutt,²Kellye Pando,²Roger Harrington
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13932]
¹Mailcode XI2, NASA Johnson Space Center, 2101 NASA Parkway, Houston, Texas, 77058 USA
²Jacobs, NASA Johnson Space Center, Houston, Texas, 77058 USA
³Department of Earth, Environmental, and Planetary Science, Case Western Reserve University, 10900 Euclid Ave, Cleveland, Ohio, 44106 USA
Published by arrangement with John Wiley & Sons

Carbonaceous chondrites of the Vigarano group (CV) are primitive (nearly un-metamorphosed) meteorites that provide a wealth of information about the early solar system, including constraints on chondrule formation, origin of calcium-aluminum inclusions, stability of organic compounds, and redox conditions. The US Antarctic meteorite collection contains 119 CV samples from 15 dense collection areas (DCAs) from the TransAntarctic Mountains; these samples have been assigned a preliminary classification as CVs, but not to the subgroups oxidized A, oxidized B, and reduced. Furthermore, variation in petrologic grade can be determined non-destructively using Raman spectroscopy. To update the classification of both subgroups and petrologic types in the collection, we have acquired magnetic susceptibility, metal and sulfide compositions, and Raman spectra. Overall, there are 55 oxidized A samples, 18 oxidized B samples, and 46 reduced samples. Several of the CVs are quite primitive (Lewis Cliffs Ice Tongue and MacAlpine Hills) but are also very small. Multiple pairing groups have been identified in the Miller Range (MIL), Queen Alexandra Range, and Larkman Nunatak DCAs, including all of the subgroups. In MIL 090981, there is evidence for multiple lithologies. We make suggested updates for all the samples, knowing that this information will help to better guide researchers interested in studying the CV chondrites in the US Antarctic meteorite collection.

¹R. Aileen Yingst et al. (>10)
Planetary Science Journal 3, 240 Open Access Link to Article [DOI 10.3847/PSJ/ac8429]
¹Planetary Science Institute, 1700 E Ft. Lowell, Suite 106, Tucson, AZ 85719, USA

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

¹Eva L. Scheller et al., (>10)
Science 378, 6624 Link to Article [DOI: 10.1126/science.abo52]
¹Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
²Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
Reprinted with permission from AAAS

The Perseverance rover landed in Jezero crater, Mars in February 2021. We used the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument to perform deep ultraviolet Raman and fluorescence spectroscopy of three rocks within the crater. We identify evidence for two distinct ancient aqueous environments at different times. Reactions with liquid water formed carbonates in an olivine-rich igneous rock. A sulfate-perchlorate mixture is present in the rocks, probably formed by later modifications of the rocks by brine. Fluorescence signatures consistent with aromatic organic compounds occur throughout these rocks, preserved in minerals related to both aqueous environments.

¹H.Chen-Chen,¹S.Pérez-Hoyos,¹A.Sánchez-Lavega,²J.Peralta
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.115393]
¹Departamento de Física Aplicada, Escuela de Ingeniería de Bilbao, Universidad del País Vasco (UPV/EHU), Bilbao 48013, Spain
²Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, University of Sevilla, Spain
Copyright Elsevier

The ubiquitous dust in the Martian environment plays a key role in its weather and climate: it must be taken into account in the interpretation of remote sensing data and observations, and could pose a potential risk to surface equipment and operations. In this study, we use observations retrieved by the Instrument Context Camera (ICC) onboard the InSight lander to evaluate the accumulation of dust on the camera lens and estimate the size of the deposited dust particles. Dust contamination is revealed as mottled pattern image artefacts on ICC observations. These were detected using a template matching blob detection algorithm and modelled with a first-order optical model to simulate their size and optical density as a function of the particle diameter. The results show a deep decay in the first 70 sols (LS = 295–337°, MY34) during which dust particles deposited at landing were mostly removed. The subsequent gradual decrease and stable behaviour in the number of detected particles is only interrupted by accumulation and removal periods around sols 160 (LS ~ 23°, MY35) and 800–1100 (LS = 9–150°, MY36). The estimated particle sizes follow a similar trend, with deposited particles due to wind-driven forces (average diameter < 50 μm) being smaller than the ones deposited by other forces during landing, with particles of up to 220 μm of diameter. The results of this study provide an additional source of information for evaluating aeolian dust processes in Mars, with quantitative results on dust accumulation and removal activity, and may contribute to a better determination of dust entrainment threshold models by constraining susceptible dust particle sizes.

^1,4,5Kereszturi Ákos,^2,4Gyollai Ildikó,^2,4Szabó Máté,^3,4Skultéti Ágnes
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.115377]
¹Konkoly Thege Miklos Astronomical Institute, Research Centre for Astronomy and Earth Sciences, Hungary
²Institute of Geological and Geochemical Research, Research Centre for Astronomy and Earth Sciences, Hungary
³Geographical Institute, Research Centre for Astronomy and Earth Sciences, Hungary
⁴CSFK, MTA Centre of Excellence, Budapest, Konkoly Thege Miklós út 15-17., H-1121, Hungary
⁵European Astrobiology Institute, Strasbourg, France
Copyright Elsevier

Shock metamorphic processes in minerals were observed in the recently fallen Chelyabinsk meteorite and compared with two infrared laboratory methods: DRIFT and ATR based spectral analysis types, attached to a Fourier Transformational Infrared Spectrometer (FTIR). Both of ATR and DRIFT methods have advantages and disadvantages for shock stage identification. However, while the ATR method has wide literature background, the DRIFT method was not used in shock metamorphic research yet, hence this study links ATR spectra with DRIFT spectra to obtain reference for such IR methods in the analysis of shock metamorphism. The results show that shock-based spectral changes could be better followed by the decreasing number of peaks with DRIFT than with ATR data; while the situation is opposite for FWHM values, which better characterizes the shock consequences from ATR data. The DRIFT analyses made from bulk meteorite material. Hence more mineral phases were identified than by separate measurements of ATR. The ATR spectra includes rather major vibration, But with DRIFT the minor bands could be also measured. Hence the other shock indicator, the disappearance of minor bands with increasing shock stage could be better followed by DRIFT. The important shock metamorphic indicator, the FWHM could be identified rather from ATR spectra, as the DRIFT spectra includes small sized peaks, and the FWHM values are near to the spectral resolution of DRIFT spectra. Both of ATR and DRIFT methods show shift of IR bands to higher wavenumber with increasing shock stage. Moreover, the DRIFT method shows the split of some minor bands in case of feldspar and pyroxene due to dimerization of silicate structure.

With increasing shock stage one band disappeared and a new one appeared in case of feldspar DRIFT data, while feldspar did not emerge using ATR observations. In case of olivine the major bands shifted by +2… +5 cm−1 using DRIFT and ATR spectra also. In case of pyroxene one band disappeared and new forbidden bands emerged. These results provide starting points to develop shock estimation using DRIFT method too, what is a much more available at various laboratories. However, it is worth mentioning that DRIFT method usually identifies more mineral phases than ATR because of the difference in spatial resolution.

¹G. Cruz Mermy,^1,2F. Schmidt,³T. Cornet⁴, I. Belgacem,⁴N. Altobelli
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.115379]
¹Université Paris-Saclay, CNRS, GEOPS, 91405, Orsay, France
²Institut Universitaire de France (IUF), France
³Aurora Technology BV for ESA, Netherlands
⁴European Space Agency (ESA), European Space Astronomy Centre (ESAC), Spain
Copyright Elsevier

Europa’s surface shows evidence of active resurfacing which can be explained by either endogenic or exogenic processes. Apart from water ice, several compounds have been proposed to account for the potential complex chemistry that could take place if a connection with the subsurface salty ocean would occur. Previous spectroscopic studies that investigated the surface composition were limited by the number of compounds to consider due to the unavailability of laboratory measurements. We now have access to optical constants and laboratory spectra of synthetic chemical compounds such as hydrated sulfates and chlorinated salts under Europa’s surface conditions.

In this study, we test for the first time the relevance of 15 potential endmembers on a Galileo/NIMS observation of a dark lineament of the Trailing Anti-Jovian hemisphere using a realistic radiative transfer modelling and a robust Bayesian inference framework. We consider an intimate mixture of 3, 4 and 5 endmembers and perform a fitting procedure on all possible combinations among the list of 15 compounds in the 1.0 – 2.4

m spectral range. At the end, 5000 combinations have been tested and analyzed. The parameters we are fitting for are the surface roughness, the volumetric abundances and the grain size. Given the fact that NIMS noise level and absolute calibration are uncertain, we have distinguished two scenarios: assuming a pessimistic signal-to-noise ratio (SNR) of 5 and an optimistic SNR of 50. For each scenario, we use several criteria to highlight the contribution of each endmember and thus identify the most relevant compounds.

We first show that no combinations using only 3 endmembers are able to accurately reproduce the observation. Then, when considering 4 and 5 endmembers together and assuming the SNR=50, there is 21 and 153 combinations that evenly reproduce the observation. From this result, we discuss the relevance of each endmember using criteria such as the Root-Mean-Square (RMS) deviation of the best-fits, the spectral contribution at each wavelength, the occurrences distribution of the selected best-fits and the numerical abundances retrieved by the fitting procedure. By grouping criteria together, we show that only sulfuric acid octahydrate and water ice appear as essential compounds. Then, hydrated sulfates are in general preferred over others compounds. This result is only valid for a lineament of the Trailing Anti-Jovian hemisphere and can be possibly extended to other lineaments in the same hemisphere. However, we show that chlorinated salts but also ammonium sulfate mascagnite ((NH4)2SO4), sodium chloride (NaCl) and even magnetite (Fe3O4) are not excluded, their contributions from the selected criteria are just less pronounced than hydrated sulfates. Nevertheless, it is clear that it is not possible to correctly distinguish between these endmembers, and even less between endmembers with similar chemical composition, at these wavelengths. We therefore propose for future investigation to either consider a mixture that would include only one representative of each chemical compound, rather than using all possible endmembers and overfitting the data.

¹Donald Lewis Bowden et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13933]
¹School of Physics and Astronomy, University of Leicester, LE1 7RH Leicester, UK
Published by arrangement with John Wiley & Sons

Askival is a light-toned, coarsely crystalline float rock, which was identified near the base of Vera Rubin Ridge in Gale crater. We have studied Askival, principally with the ChemCam instrument but also using APXS compositional data and MAHLI images. Askival and an earlier identified sample, Bindi, represent two rare examples of feldspathic cumulate float rocks in Gale crater with >65% relict plagioclase. Bindi appears unaltered whereas Askival shows textural and compositional signatures of silicification, along with alkali remobilization and hydration. Askival likely experienced multiple stages of alteration, occurring first through acidic hydrolysis of metal cations, followed by deposition of silica and possible phyllosilicates at low T and neutral-alkaline pH. Through laser-induced breakdown spectroscopy compositional analyses and normative calculations, we suggest that an assemblage of Fe-Mg silicates including amphibole and pyroxene, Fe phases, and possibly Mg-rich phyllosilicate are present. Thermodynamic modeling of the more pristine Bindi composition predicts that amphibole and feldspar are stable within an upper crustal setting. This is consistent with the presence of amphibole in the parent igneous rocks of Askival and suggests that the paucity of amphiboles in other known Martian samples reflects the lack of representative samples of the Martian crust rather than their absence on Mars.

^1,2Lukas Manske,^1,2Kai Wünnemann,³Kosuke Kurosawa
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2022JE007426]
¹Museum für Naturkunde Berlin, Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany
²Department of Earth Sciences, Freie Universität Berlin, Berlin, Germany
³Planetary Exploration Research Center, Chiba Institute of Technology, Narashino, Japan
Published by arrangement with John Wiley & Sons

Melting and vaporization of rocks in impact cratering is mostly attributed to be a consequence of shock compression. However, other mechanism such as plastic work and decompression by structural uplift also contribute to melt production. In this study we expand the commonly used method to determine shock-induced melting in numerical models from the peak shock pressure by a new approach to account for additional heating due plastic work and internal friction. We compare our new approach with the straight-forward method to simply quantify melting from the temperature relative to the solidus temperature at any arbitrary point in time in the course of crater formation. This much simpler method does account for plastic work but suffers from reduced accuracy due to numerical diffusion inherent to ongoing advection in impact crater formation models. We demonstrate that our new approach is more accurate than previous methods in particular for quantitative determination of impact melt distribution in final crater structures. In addition, we assess the contribution of plastic work to the overall melt volume and find, that melting is dominated by plastic work for impacts at velocities smaller than 7.5–12.5 km/s in rocks, depending on the material strength. At higher impact velocities shock compression is the dominating mechanism for melting. Here, the conventional peak shock pressure method provides similar results compared with our new model. Our method serves as a powerful tool to accurately determine impact-induced heating in particular at relatively low-velocity impacts.

¹Kishan Tiwari,¹Sujoy Ghosh,²Masaaki Miyahara,³Dwijesh Ray
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007420]
¹Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur, India
²Graduate School of Advanced Science and Engineering, Hiroshima University, Higashihiroshima, Japan
³Planetary Sciences Division, Physical Research Laboratory, Ahmedabad, India
Published by arrangement with John Wiley & Sons

Abundant vesicles are found in terrestrial rocks, basaltic meteorites, and carbonaceous chondrites which testify to the presence of significant quantities of volatiles and favorable conditions for vesiculation. Furthermore, vesicular olivine has been reported in terrestrial rocks and carbonaceous chondrites. However, vesicles in the ordinary chondrites are rare due to their low volatile content and obliteration by the late impact events. Here, we report the first evidence of vesicular olivine (Fo76) and pyroxene (En73–81Fs17–26Wo01–02) in an ordinary chondrite. The vesicular texture in the shocked Kamargaon L6 chondrite possibly formed due to localized melting during a shock event and subsequent degassing of volatiles after decompression. We propose three possible mechanisms for vesicle formation in the Kamargaon meteorite: (a) liberation of S2 vapor, (b) evaporation of moderately volatile elements (MVEs) like Na and Mn, and (c) vaporization of olivine and pyroxene, by constraining the primary abundance of volatiles based on the observed volume of vesicles. We suggest that all three or any combination of these mechanisms could be responsible for vesicle formation. Segmented texture in olivine is also observed in the shock vein (SV) of the Kamargaon chondrite. The segmentation has developed due to the formation of sub-grain boundaries during the recovery process when grains were subjected to localized shear stress. Average shock pressure and temperature conditions in the SV are ∼24–25 GPa and ∼2310–2633K, respectively. The thermal model of the SV cooling gives the crystallization time of ∼50 ms and shock pulse duration of ∼2s.