¹Annemiek C. Waajen,^2,3R. Prescott,¹Charles S. Cockell
Astrobiology 22, 5 Link to Article [https://doi.org/10.1089/ast.2021.0089]
¹Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
²Department of Environmental Health Sciences, University of South Carolina, Columbia South Carolina, USA.
³School of Life Sciences, University of Hawai‘i at Mānoa, Honolulu, Hawai‘i, USA.

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¹Nathalie Turenne,¹Sahejpal Sidhu,¹Daniel M. Applin,¹Edward A. Cloutis,¹Z.U. Wolf,²Stanley A. Mertzman,³Elisabeth M. Hausrath,⁴Teresa Fornaro,⁵Adrian Brown
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115448]
¹Centre for Terrestrial and Planetary Exploration, University of Winnipeg, Winnipeg, Manitoba R3B 2E9, Canada
²Department of Earth and Environment, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604-3003, USA
³Department of Geoscience, University of Nevada, Las Vegas, NV 89154, USA
⁴INAF-Astrophysical Observatory of Arcetri, Largo E. Fermi 5, 50125 Florence, Italy
⁵Plancius Research, Severna Park, MD 21146, USA
Copyright Elsevier

Spectral reflectance properties of nontronite [a phyllosilicate with an ideal formula of Na0.3Fe23+(Si,Al)4O10(OH)2·nH2O] were investigated under simulated Mars surface conditions of atmospheric pressure and composition, and after heating to 110°, 180°, and 300 °C. The data can be used to determine the conditions to which nontronites on the martian surface may have been subjected. Nontronite’s spectral features include Fe3+ associated absorption features below 1000 nm, H2O/OH features near 1400 nm, H2O features near 1900 nm, a characteristic metal-OH (Fe3+) feature in the 2280–2290 nm region, and an additional Fe-OH absorption feature near 2400 nm. Heating in a low-pressure CO2 environment leads to the loss of Fe-OH-associated features below 1000 nm at temperatures as low as 110 °C. Both OH and H2O are progressively lost upon heating to 300 °C, but small, spectrally-detectable amounts remain at 300 °C. The longer wavelength Fe-OH absorption bands in the 2280 and 2400 nm region persist up to these temperatures. Comparison to other smectites and Fe-rich phyllosilicates show that a strong 2280–2290 nm absorption feature and weak or absent ~2320 nm feature are unique to nontronite. A broader absorption feature in the 2300 nm region suggests the presence of nontronite and one or more Mg-bearing phyllosilicate(s). A Mg+Fe3+ phyllosilicate is implausible because of the difficulty in incorporating Mg2+ into the dioctahedral structure of nontronite. With increasing grain size, nontronite spectra become darker and progressively more blue-sloped beyond ~1500 nm with absorption bands showing increasing depth until saturation is reached for some of them beyond a few hundred-micron grain size. The spectral changes documented in this study, as well as a comparison to previous studies, suggest that the absorption features associated with nontronite can be used to place constraints on conditions that nontronite may have been exposed to in the past. This study demonstrates that dehydration as well as dehydroxylation can occur at temperatures <300 °C.

^1,2Ildiko Gyollai,^3,4Elias Chatzitheodoridis,^2,5Ákos Kereszturi,^1,2Máté Szabó
Meteortics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13950]
¹Institute for Geological and Geochemical Research, Research Centre for Astronomy and Earth Sciences, ELKH, Budapest, Hungary
²CSFK, MTA Centre of Excellence, Konkoly Thege Miklós út 15-17, Budapest, H-1121 Hungary
³Department of Geological Sciences, School of Mining and Metallurgical Engineering, National Technical University of Athens, Athens, Greece
⁴Network of Researchers on the Chemical Evolution of Life (NoRCEL), Leeds, UK
⁵Konkoly Thege Miklos Astronomical Institute, Research Centre for Astronomy and Earth Sciences, ELKH, Budapest, Hungary
Published by arrangement with John Wiley & Sons

We studied the occurrence of secondary minerals and inferred their formation in the Yamato-000593 Martian meteorite using multiple technological approaches such as electron probe micro analysis, optical microscope, Raman spectroscopy, scanning electron microscopy, as well as Fourier transform-infrared microscopy and spectroscopy. Two separate hydrothermal alteration events and their sequence of formation (based on superpositional relationship) can be identified: an elevated temperature phase producing high-temperature sulfidic hydrothermal alteration and a lower temperature hydrothermal alteration phase by iron-rich fluids. This meteorite shows signatures more compatible with magmatic effects, rather than impact-induced hydrothermal alteration, as has been proposed earlier. The sulfidic alteration probably formed by magmatic hydrothermal fluids, whereas iron-rich hydrothermal fluid circulation after a possible early impact event has also been proposed, when the fluids cooled down to 50 °C. Most of the secondary minerals formed at alkaline-neutral conditions, and the few observed signatures (clay–silica-bearing veins, siderite-iron-oxide veins) of briny conditions are probably from local spatial effects in larger cavities. The ferrous minerals (hematite and siderite) along the fractures could be crystallized from Fe-HCO3-bearing fluids. Alternatively, the primary magmatic minerals could have been oxidized easily (Fe-rich olivines, magnetite) during the cooling to iron oxides (hematite, goethite). The results suggest the possible existence of at least ephemerally habitable environments on Mars, mainly at volcanically heated locations. Following published geochemical models, the carbonates formed within acidic-circumneutral condition, which was followed by formation of phyllosilicates in alkaline condition.

^1,2Yuan Li,³Michael Wiedenbeck,⁵Brian Monteleone,⁴Rajdeep Dasgupta,⁴Gelu Costin,^1,2Zenghao Gao,^1,2Wenhua Lu
Earth and Planetary Science Letters 605, 118032 Link to Article [https://doi.org/10.1016/j.epsl.2023.118032]
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
³Helmholtz Zentrum Potsdam, Deutsches GeoForschungZentrum, GFZ, Telegrafenberg, 14473 Potsdam, Germany
⁴Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
⁵Department of Earth, Environmental, and Planetary Sciences, Rice University, 6100 Main Street, MS 126, Houston, TX 77005, USA
Copyright Elsevier

¹A. C. Fox,²R. S. Jakubek,³J. L. Eigenbrode
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007624]
¹NASA Postdoctoral Program – NASA Johnson Space Center Houston, TX, USA, Houston
²NASA Johnson Space Center, Jacobs, Houston, TX, 77058 USA
³Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA
Published by arranegement with John Wiley & Sons

The search for potential molecular biosignatures on Mars is complicated by its harsh radiation environment that can alter or destroy the primary molecular features diagnostic of an organic compound’s origins. In this work, mixtures of Mars-relevant minerals and organic material representing different types and different chemical

states of sedimentary organic material common in the terrestrial geologic record were irradiated with 200 MeV protons to simulate the effect of exposure to galactic cosmic rays and solar energetic particles over geological timescales and characterized using a deep UV Raman and fluorescence spectrometer analogous to the SHERLOC instrument on the Mars 2020 Perseverance Rover. We found that exposure to ionizing radiation generally results in the loss of molecular features diagnostic of an organic material’s origins in favor of increasingly aromatic compounds or macromolecules. However, these radiolytic effects can be mitigated by the formation of macromolecular structures that are more resistant to radiolysis compared to individual compounds, and potentially through associations with specific minerals that enable increased polymerization. Based on these results, rocks observed by the SHERLOC instrument with fluorescence or Raman features associated with non-aromatic molecular features and/or kerogen-like structures may indicate less radiolytically damaged organic material that should be prioritized for return as it may retain some primary, diagnostic molecular features.

¹C. A. Lorenz,¹M. A. Ivanova,²N. G. Zinovieva,¹K. M. Ryazantsev,¹A. V. Korochantsev
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13951]
¹Vernadsky Institute of Geochemistry and Analytical Chemistry RAS, Kosygin St. 19, Moscow, 119991 Russia
²Lomonosov Moscow State University, Leninskie Gory, Moscow, 119991 Russia
Published by arrangement with John Wiley & Sons

Metal-rich carbonaceous CB chondrites are generally assumed to be materials accreted from the gas–dust plume formed in catastrophic collisions of planetesimals, at least one of which was differentiated into a metal core and silicate shell. Micron-sized inclusions of siliceous alkali-rich glasses associated with sulfides were found in the metal globules of the Sierra Gorda 013 (SG 013), a CBa-like chondrite. These inclusions are unusual carriers of volatile alkalis which are commonly depleted in CB chondrites. The inclusions are presented by two types: (1) Al-bearing Nb-poor glass associated with daubréelite and (2) Nb-bearing Ca,Al,Mg-poor glass associated with an unknown Na-bearing Cr-sulfide. The glass compositions do not correspond to equilibrium condensation, evaporation, or melting. The Nb-bearing glass has a superchondritic Nb/Ta ratio (31) most likely indicating the fractionation of Nb and Ta in the high-temperature gas–dust impact plume due to condensation from vapor or evaporation of precursor Nb-rich particles. The glasses are interpreted as reaction products between refractory plume condensate particles (or possibly planetary or chondritic solids) with relatively low-temperature K-Na-Si-rich gas in oxidized conditions, possibly in a common plume vapor reservoir. Compositional differences indicate that the glasses and sulfides originated from several different sources under different fO2, fS2, and T conditions and were likely combined together and transported to the metal globule formation region by material flows in the heterogeneous impact plume. The glass–sulfide particles were enclosed in the globules aggregated from smaller solid or molten metal grains. The metal globules were further melted during transport to the high-temperature plume region or by plume shockwave heating. Thus, the composition of the glasses, the host metal, and the main mass of SG 013 shows dynamic heterogeneity of physical conditions and impact plume composition after a large-scale planetesimal collision.

¹M. J. Rucks,²J. M. Winey,²Y. Toyoda,^2,3Y. M. Gupta,¹T. S. Duffy
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007642]
¹Department of Geosciences, Princeton University, Princeton, New Jersey, 08544 USA
²Institute for Shock Physics, Washington State University, Pullman, Washington, 99164-2816 USA
³Department of Physics, Washington State University, Pullman, Washington, 99164-2816 USA
Published by arrangement with Hohn Wiley & Sons

Apatite is a phosphate mineral relevant to shock metamorphism in planetary materials. Here, we report on the response of natural fluorapatite from Durango, Mexico under shock wave loading between 14.5 and 119.5 GPa. Wave profile measurements were obtained in plate-impact experiments conducted on [0001]-oriented fluorapatite single crystals. To 30 GPa peak stresses, we observed a two-wave structure indicating an elastic-inelastic response with elastic wave amplitudes of 10.5 – 13.1 GPa. Between 39.1 – 62.1 GPa, a complex wave structure was observed involving the propagation of three waves. At and above 73.7 GPa, only a single shock wave was observed. The data above 73.7 GPa provided the following linear shock velocity – particle velocity relationship: Us = 6.5(2) + 0.78(6) up, (mm/μs). Above 80 GPa, the densities in the shocked state exceed both the extrapolated 300-K density of fluorapatite and the predicted 300-K density for a mixture of the high-pressure assemblage, tuite and CaF2. This result indicates that fluorapatite undergoes a transition to a denser structure under shock loading at these conditions. The shock response of fluorapatite is observed to be similar to enstatite but stiffer than quartz and albite at the stresses examined in this work.

^1,2Alison R. Santos,¹Martha S. Gilmore,¹James P. Greenwood,³ Leah M. Nakley,^3,4Kyle Phillips,³Tibor Kremic,¹Xavier Lopez
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007423]
¹Department of Earth and Environmental Sciences, Wesleyan University, 265 Church St., Middletown, CT, 06459 United States
²Previously at: NASA Postdoctoral Program Fellow, NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, OH 44135
³NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, OH, 44135 United States
⁴Previously at: HX5 Sierra, LLC, 21000 Brookpark Rd., Cleveland, OH 44135.
Published by arrangement with John Wiley & Sons

We report two experiments using 13 mineral and rock samples exposed to a complex synthetic Venus atmosphere composed of nine gases for durations of 30 and 11 days conducted using the NASA Glenn Extreme Environment Rig (GEER). Examination of our run products using a scanning electron microscope equipped with an energy dispersive spectrometer reveals secondary minerals predominantly formed from reactions of Fe and Ca in the solid samples with sulfur in the atmospheric gas, results largely predicted in the literature, and indicating that such reactions between rocks and the atmosphere at the Venus surface may occur rapidly. Samples that displayed larger degrees of reaction include calcite (forming Ca-sulfate), Fe-Ti oxide (forming an Fe,S phase), biotite (forming an Fe,S phase), chalcopyrite (forming a new Cu,Fe-sulfide and a Ag,Cl phase), and Mid-Ocean Ridge Basalt glass (forming a Ca- and S-bearing phase, Fe- and S-bearing phase, and an Fe-oxide); pyrite was observed to be stable in our 30-day experiment. These reactions indicate that the fS2 of the experiments was above or at the high end of what is thermodynamically predicted for the Venus surface. Apatite, feldspars, actinolite, and quartz did not change in this time frame. The presence of multiple S species in GEER may explain dissimilarities in the style of reactions seen in previous experiments with simpler gas mixtures.

¹Walter Goetz et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2021JE007101]
¹Max-Planck-Institut für Sonnensystemforschung (MPS), D-37077 Göttingen, Germany
Published by arrangement with John Wiley & Sons

Laser-Induced Breakdown Spectroscopy, as utilized by the ChemCam instrument onboard the Curiosity rover, detected enhanced abundances of the element copper. Since landing in Gale crater (August 6, 2012) 10 enhancements in copper abundance were observed during 3007 Martian days (sols) of rover operations and 24 km of driving (as of January 20, 2021). The most prominent ones were found in the Kimberley area on the crater floor (Aeolis Palus) and in Glen Torridon on the lower flanks of Aeolis Mons (Mt. Sharp). Enhancements in copper record the former existence of modestly acidic and oxidizing fluids, which were more oxidizing in Kimberley than in Glen Torridon. Of the two main types of bedrock in the lowest part of Glen Torridon, Mg-rich ‘coherent’ and K-rich ‘rubbly’ (named based on their outcrop expression), copper was only detected in coherent, not in rubbly bedrock. The difference between these two types of bedrock may be due to difference in provenance. Alternatively, based on a recently developed lacustrine-groundwater mixing model, we suggest that rubbly bedrock was altered by modestly acidic, shallow-subsurface lake water that leached out both copper and manganese, while coherent bedrock was affected by dominantly alkaline fluids which would be consistent with its mineralogical composition (including siderite) as returned by the CheMin instrument onboard the rover. Higher up in Glen Torridon, ChemCam data indicated significant gradients in copper concentration in coherent bedrock on a local scale of only few meters, which suggests a different alteration style and possibly different types of diagenetic fluids.

¹Yuki Masuda,¹Tetsuya Yokoyama
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.01.024]
¹Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
Copyright Elsevier

Calcium-aluminum-rich inclusions (CAIs) in chondrite meteorites are the oldest rocks in the Solar System and were formed by condensation from nebular gas. Recent mass spectrometric measurements have revealed that CAIs possess nucleosynthetic isotopic compositions different from those of terrestrial materials for various elements, indicating a heterogeneous distribution of nuclides from various stellar sources in the early Solar System. CAIs are classified into coarse-grained (CGs) and fine-grained (FGs) inclusions. The former have experienced secondary melting through thermal events after their formation, while the latter evidently avoided the remelting. Thus, FGs are considered to be direct condensates from a high-temperature gas, making them ideal for investigation of the origin and formation process of CAIs. In this study, the elemental abundances and Sr isotopic compositions in eight FGs from a carbonaceous chondrite Allende were analyzed by utilizing a micromilling technique. These FG samples were found to have rare-earth element (REE) patterns reflecting various degrees of elemental fractionation and variable µ84Sr values ranging from 61 to 844 ppm. It cannot be ruled out that matrix contamination during micromilling or secondary alteration on the Allende parent body has affected the elemental abundances and µ84Sr values observed in FGs to some extent; however, the large variation in µ84Sr values could reflect the variability in the FG formation processes. Importantly, REE-fractionated FGs, which were depleted in heavy REEs relative to light REEs, had relatively high µ84Sr values. This suggests that the formation of REE-fractionated FGs was triggered by rapid heating events, such as FU Orionis that occurred periodically in the early Solar System, and that at least two different heating events probably formed FGs with two different µ84Sr values.