Oxygen isotope exchange kinetics between CAI melt and carbon monoxide gas: Implication for CAI formation in the earliest Solar System

1Daiki Yamamoto,2Noriyuki Kawasaki,3,4Shogo Tachibana,3Michiru Kamibayashi,2Hisayoshi Yurimoto
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2022.09.006]
1Department of Earth and Planetary Science, Tokyo Institute of Technology, Ookayama, Tokyo 152-8550, Japan
2Department of Natural History Sciences, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
3Department of Earth and Planetary Science, The University of Tokyo, Hongo, Tokyo 113-0033, Japan
4Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa
Copyright: Elsevier

Coarse-grained igneous calcium-aluminum-rich inclusions (CAIs) are suggested to have experienced gas-melt isotope exchange of oxygen during the melting events of their precursors. Therefore, their oxygen isotope variation would preserve information about the high-temperature processes in the earliest Solar System. We experimentally determined oxygen isotope exchange kinetics between CAI analog melt and carbon monoxide (CO) gas at 1420°C and 1460°C under CO gas partial pressures of 0.1, 0.5, and 1 Pa to understand the role of CO gas on the oxygen isotope exchange. We observed oxygen isotope zoning profiles inside the reacted samples that formed through the oxygen isotope exchange reaction at the melt surface and oxygen diffusion in the melt. The zoning profiles were fitted using a three-dimensional spherical diffusion model with time-dependent surface concentration. The oxygen isotope exchange efficiency for colliding CO molecules is estimated to be ∼3.3 × 10–4, which is much smaller than that for H2O (0.28). The oxygen diffusion coefficient obtained in this study is similar to that obtained in the oxygen isotope exchange experiments between the CAI melt and H2O, suggesting that the diffusion species in the melt is O2–, despite the surrounding atmospheres.

A comparison of the isotope exchange reaction kinetics between (1) CAI melt and CO gas, (2) CAI melt and H2O gas, and (3) CO and H2O gases shows that the reaction rate decreases in the order of (3), (2), and (1). The rapid isotope exchange of the reaction (1) indicates that the oxygen isotopic compositions of H2O and CO should have been equilibrated during the melting and crystallization processes of igneous CAIs. Both H2O and CO change the oxygen isotope compositions of molten CAI in the same direction, although reaction (2) controls the isotope exchange timescale between the CAI melt and surrounding gas. Our dataset demonstrates that type B CAIs having melilite with homogeneous oxygen isotope composition should have been heated for 2–3 days at PH2 > 100 Pa above the melilite liquidus (∼1400°C) in the solar protoplanetary disk.

Fe-Rich Fossil Vents as Mars Analog Samples: Identification of Extinct Chimneys in Miocene Marine Sediments Using Raman Spectroscopy, X-Ray Diffraction, and Scanning Electron Microscopy–Energy Dispersive X-Ray Spectroscopy

1,2Lucas Demaret,3Ian B. Hutchinson,3Richard Ingley,3Howell G.M. Edwards,
4Nathalie Fagel,5Philippe Compere,2Emmanuelle J. Javaux,1Gauthier Eppe,1Cédric Malherbe
Astrobiology 22, 9 Link to Article [https://doi.org/10.1089/ast.2021.0128]
1Mass Spectrometry Laboratory, MolSys Research Unit, University of Liege, Liege, Belgium.
2Early Life Traces & Evolution-Astrobiology, UR Astrobiology, University of Liege, Liege, Belgium.
3Department of Physics and Astronomy, University of Leicester, Leicester, United Kingdom.
4Laboratory Argiles, Géochimie et Environnements Sédimentaires, University of Liege, Liege, Belgium.
5Laboratory of Functional and Evolutionary Morphology, UR FOCUS, and Centre for Applied Research and
Education in Microscopy (CAREM), University of Liege, Liege, Belgium.

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Blue on Red: Chemical conditions of liquid water emerging on simulated Martian regolith

1,2Piotr Rzymski,3Piotr Klimaszyk,4Nadiia Kasianchuk,2Paulina Jakubiak,5Jędrzej Proch,5Przemysław Niedzielski
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.115263]
1Department of Environmental Medicine, Poznan University of Medical Sciences, Poznan, Poland
2Integrated Science Association (ISA), Universal Scientific Education and Research Network (USERN), Poznań, Poland
3Department of Water Protection, Adam Mickiewicz University, 61-642 Poznań, Poland
4Faculty of Biology, Adam Mickiewicz University, 61-642 Poznań, Poland
5Department of Analytical Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Poznan, Poland
Copyright Elsevier

There is evidence of large subglacial reservoirs of liquid water on Mars, while the debate continues on whether any surface water intermittently flows following the subsurface ice melting in selected locations. The chemical conditions of waters that could be present on Mars were previously subject to modeling studies or experimental research that did not involve perchlorates which are known to be present in Martian regolith. Therefore, the present experimental research aimed to understand the chemistry of water incubated for 21 days with the Martian regolith simulant MGS-1 mixed with different levels of perchlorate (0.25–1.0% corresponding to 1.5–6.0 mM ClO4− ions). The dissolution of chemical compounds from MGS-1 was rapid with electric conductivity (EC) in the 1.8–2.3 mS/cm range after 1 h incubation. Throughout the experiment, fluctuations of pH, EC and oxidation-reduction potential were observed, although generally, the water was rich in ions, highly oxidized and had a circumneutral pH. Dominant elements included S, Mg, Ca, Na, K and Fe. Two patterns of element concentrations were observed: (1) a rapid increase with a peak 3 h after flooding the regolith and then a gradual decrease indicating adsorption and immobilization (Al, Cr, Fe, Si and Ti), and (2) a gradual increase in concentration throughout the experiment (Ca, K, Mg, Na and S). The presence of perchlorate in the simulant did not affect the general patterns of water chemistry parameters, although it appeared to enhance the leaching out of Mg, Na, S (with max concentrations noted in the presence of 1.0% perchlorate), Al, Ca (0.5%) and Cr, Fe, Si and Ti (0.25%). No detectable concentrations of Mn and P were leached from the regolith simulant throughout the experiment. This study provides a pilot experimental overview of the combined physicochemical conditions that modern liquid water on Mars could present with the potential implications for the survival of biological life and use as an in situ resource.

Sedimentary Organics in Glen Torridon, Gale Crater, Mars: Results from the SAM Instrument Suite and Supporting Laboratory Analyses

1,2 3M.Millan et al. (>10)
Joournal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2021JE007107]
1Department of Biology, Georgetown University, Washington, DC, USA
2NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, USA
3Laboratoire Atmosphère, Observations Spatiales (LATMOS), LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
Published by arrangement with John Wiley & Sons

The Sample Analysis at Mars (SAM) suite instrument on board NASA’s Curiosity rover has characterized the inorganic and organic chemical composition of seven samples from the Glen Torridon clay-bearing unit. A variety of organic molecules were detected with SAM using pyrolysis (up to ∼850°C) and wet chemistry experiments coupled with evolved gas analysis (EGA) and gas chromatography-mass spectrometry (GCMS). SAM EGA and GCMS analyses revealed a greater diversity and abundance of sulfur-bearing aliphatic and aromatic organic compounds in the sediments of this Gale crater unit than earlier in the mission. We also report the detection of nitrogen-containing, oxygen-containing, and chlorine-containing molecules, as well as polycyclic aromatic hydrocarbons found in Glen Torridon (GT), although the sources of some of these organics may be related to the presence of chemical reagents in the SAM instrument background. However, sulfur-bearing organics released at high temperature (>600°C) are likely derived from martian sources (e.g., igneous, hydrothermal, atmospheric, or biological) or exogenous sources and consistent with the presence of recalcitrant organic materials in the sample. The SAM measurements of the GT clay-bearing unit expand the inventory of organic matter present in Gale crater and is also consistent with the hypothesis that clay minerals played an important role in the preservation of ancient refractory organic matter on Mars. These findings deepen our understanding of the past habitability and biological potential of Gale crater.

Protracted Hydrogeological Activity in Arabia Terra, Mars: Evidence from the Structure and Mineralogy of the Layered Deposits of Becquerel Crater

1G. Schmidt,2E. Luzzi,2A.P. Rossi,3M. Pondrelli,1A. Apuzzo,1F. Salvini
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007320]
1Department of Science, Università degli studi Roma Tre, Rome, Italy
2Department of Physics and Earth Sciences, Jacobs University Bremen, Bremen, Germany
3International Research School of Planetary Sciences, Università d’Annunzio, Pescara, Italy
Published by arrangement with John Wiley & Sons

The formation of layered mounds on Mars remains a major topic of debate, with the relationship between their deposition and chemical alteration a major aspect still to be constrained. The association these deposits have with hydrated minerals indicates aqueous processes were active in their past, however the extent and duration of this aqueous period has yet to be fully realized. We studied compositional, stratigraphical, and structural characteristics of two separate layered deposits within Becquerel crater, Arabia Terra, to constrain their origins and the intensity of past aqueous activity. We find that due to key differences in composition, layering, and deformation between the two deposits, the timing of important depositional changes within Becquerel can be identified. We propose a scenario involving differences in fluid expulsion intensity and water level between the two layered deposits, in which diverse depositional and post-depositional environments were able to form. Furthermore, internal collapsing and deformation of the main mound might reflect that fluid upwelling persisted below the mound after formation. Determining the relationship between these two deposits is an important step in unraveling the past climate of Arabia Terra, and more broadly Mars. The evidence of protracted fluid expulsion represents a unique opportunity for future missions searching for signs of past life.

A Micro Mid-Infrared Spectroscopic Study of Chang’e-5 Sample

1Yazhou Yang,2Te Jiang,1Yang Liu,1Yuchen Xu,2,3Hao Zhang,4Heng-Ci Tian,4Wei Yang,1Yongliao Zou
Journal of Geophysical Research (Planets)(In Press) Link to Article [https://doi.org/10.1029/2022JE007453]
1State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, China
2Planetary Science Institute, School of Earth Sciences, China University of Geosciences, Wuhan, China
3CAS Center for Excellence in Comparative Planetology, Hefei, China
4Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
Published by arrangement with John Wiley & Sons

The Chang’e-5 (CE-5) mission has successfully returned samples from a site that is much younger than the sites of all previous lunar sampling missions. Sample analysis results reported so far have revealed a more complex sampling area than previously thought, casting uncertainties over the interpretation of remote sensing spectral data and the U and Th abundance derived from the orbital data. Laboratory spectral measurement of the returned samples can serve as validation of remote sensing observations and thus help refine our understanding of the geological evolution of the landing region. In this study we report detailed micro mid-infrared (MIR) spectral characteristics of individual soil grains of CE-5 samples. The spectral analysis results show that the CE-5 olivine grains have low Fo (molar Mg/[Mg + Fe] × 100) consistent with previous studies, indicating a Fe-rich source region of the mantle or a highly evolved magma. These olivine grains show high level of crystallinity, implying low degree of space weathering. Most of the CE-5 glasses analyzed are spectrally consistent with mare impact glasses, despite that a few of them may have a volcanic origin. These laboratory spectral analysis of CE-5 samples in the MIR wavelengths at a micro scale, together with the derived MIR optical constants of the olivine, pyroxene, plagioclase, and glass grains, provide important input for the modeling and interpretation of thermal remote sensing data of the Moon.

The distribution of clay minerals and their impact on diagenesis in Glen Torridon, Gale crater, Mars

1A.Rudolph et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2021JE007098]
1Purdue University, West Lafayette, United States
Published by arrangement with John Wiley & Sons

Glen Torridon (GT) is a recessive-trough feature on the northwestern slope of “Mt. Sharp” in Gale crater, Mars with the highest Fe-/Mg-phyllosilicates abundances detected by the Curiosity rover to date. Understanding the origin of these clay minerals and their relationship with diagenetic processes is critical for reconstructing the nature and habitability of past surface and subsurface environments in Gale crater. We aim to constrain the distribution and extent of diagenesis using compositional and morphological trends observed by visible-to-near infrared reflectance spectra in GT from Mastcam and ChemCam, supported by high-resolution images from the Mars Hand Lens Imager. Spectral features consistent with nontronite and fine-grained red hematite are ubiquitous throughout lower GT, and are strongest where diagenetic features are limited, suggesting that both were formed early, before burial. Diagenetic features increase in both abundance and diversity farther up-section, and we observe morphologic evidence for multiple episodes of diagenesis, with the edge of a diagenetic front partially preserved in the middle stratigraphic member, Knockfarril Hill. Near the contact between GT and the overlying Greenheugh pediment capping unit, we observe a lack of clay minerals with signatures consistent instead with coarse-grained gray hematite, likely formed through late-diagenetic alteration. We hypothesize that the sandstone-dominant Stimson formation acted as a conduit for diagenetic fluid flow into the area and that the clay-rich impermeable GT slowed the flow of those fluids, leading to enhanced alteration surrounding the clay-rich portions of GT, including within the nearby Vera Rubin ridge.

Diverse Assemblage of Presolar and Solar System Materials in Anhydrous Interplanetary Dust Particles: Coordinated NanoSIMS and TEM Analyses

Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2022.09.005]
1Astromaterials Research and Exploration Science, NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX 77058, USA
Copyright Elsevier

A coordinated TEM and NanoSIMS isotopic imaging study of microtome sections of three anhydrous interplanetary dust particles (IDPs) revealed a diverse collection of primitive materials having disparate origins and histories. Presolar silicate grains that likely originated in asymptotic giant branch (AGB) stars were present in each IDP at abundances ranging from 140 (+320/-120) ppm to 2000 (+4600/-1700) ppm. A unique compound presolar grain was identified that consisted of a crystalline spinel core and amorphous silicate mantle having heterogeneous Fe content. This compound grain traces the changing conditions in the circumstellar region during condensation and is the first identified presolar spinel in an IDP. A presolar SiC grain, also rare in IDPs, was found to be enriched in 13C, 14N, and 28Si, consistent with mainstream SiC that originated in ∼solar metallicity AGB stars. We determine presolar spinel and presolar SiC abundances of 760 (+1700/-630) ppm and 190 (+440/-160) ppm, respectively, in the individual IDPs.

Two elongate whisker-like enstatite grains and one platy enstatite were found to have near-terrestrial O isotopic compositions (δ18O = -17 – 18 ‰) and show chemical evidence of equilibrium condensation from a high temperature gas. Two highly 16O-rich silicates with near-solar O isotopic compositions (δ18O = -79 ‰ and -83 ‰) were also identified and may represent the primordial dust reservoir. These silicates were crystalline equilibrated aggregates. The wide range of isotopic compositions observed in these silicate grains suggests they condensed from isotopically diverse reservoirs in the protoplanetary disk in different locations and/or times. The 16O-rich grains likely condensed in the inner solar system and were subsequently transported to the outer solar system, while grains having terrestrial O isotopic compositions likely condensed from the gas phase in the terrestrial planet forming region or beyond.

The IDPs showed bulk 15N enrichments (δ15N = 15 – 129 ‰) and contained 15N-rich hotspots up to 1150 ‰, consistent with the presence of molecular cloud material. IDPs U2015D21 and W7013E17 had bulk O isotopic compositions that were offset from the carbonaceous chondrite anhydrous minerals line by ∼10 ‰ to more 17O-rich compositions. This 17O enrichment cannot be explained by the observed abundance of 17O-rich presolar grains in these particles and the source remains unknown. IDP W7027E6 had an unusual isotopically heavy bulk O isotopic composition (δ17,18O = 39 ‰, Δ17O = 19 ‰). W7027E6 lacked hydrous phases and was therefore not likely altered by isotopically heavy primordial water. We propose that the high temperature mineral assemblage in W7027E6 condensed in the inner solar system from an 16O-poor reservoir that existed prior to O isotope homogenization in the early nebula and was subsequently transported to the outer solar system.

Synthesis and Stability of an Eight-Coordinated Fe3O4 High-Pressure Phase: Implications for the Mantle Structure of Super-Earths

1C. C. Zurkowski,1J. Yang,1S. Chariton,2V. B. Prakapenka,1Y. Fei
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2022JE007344]
1Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC, USA
2Center for Advanced Radiation Sources, The University of Chicago, Lemont, IL, USA
Published by arrangement with John Wiley & Sons

Super-Earths ranging up to 10 Earth masses (ME) with Earth-like density are common among the observed exoplanets thus far, but their measured masses and radii do not uniquely elucidate their internal structure. Exploring the phase transitions in the Mg-silicates that define the mantle-structure of super-Earths is critical to characterizing their interiors, yet the relevant terapascal conditions are experimentally challenging for direct structural analysis. Here we investigated the crystal chemistry of Fe3O4 as a low-pressure analog to Mg2SiO4 between 45–115 GPa and up to 3000 K using powder and single crystal X-ray diffraction in the laser-heated diamond anvil cell. Between 60–115 GPa and above 2000 K, Fe3O4 adopts an 8-fold coordinated Th3P4-type structure (I-43d, Z = 4) with disordered Fe2+ and Fe3+ into one metal site. This Fe-oxide phase is isostructural with that predicted for Mg2SiO4 above 500 GPa in super-Earth mantles and suggests that Mg2SiO4 can incorporate both ferric and ferrous iron at these conditions. The pressure-volume behavior observed in this 8-fold coordinated Fe3O4 indicates a maximum 4% density increase across the 6- to 8-fold coordination transition in the analog Mg-silicate. Reassessment of the FeO—Fe3O4 fugacity buffer considering the Fe3O4 phase relationships identified in this study reveals that increasing pressure and temperature to 120 GPa and 3000 K in Earth and planetary mantles drives iron toward oxidation.

Sedimentological and Geochemical Perspectives on a Marginal Lake Environment Recorded in the Hartmann’s Valley and Karasburg Members of the Murray Formation, Gale Crater, Mars

1S. Gwizd et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2022JE007280]
1Department of Earth and Planetary Sciences, University of Tennessee at Knoxville, Knoxville, TN, USA
Published by arrangement with John Wiley & Sons

This study utilizes instruments from the Curiosity rover payload to develop an integrated paleoenvironmental and compositional reconstruction for the 65-m thick interval of stratigraphy comprising the Hartmann’s Valley and Karasburg members of the Murray formation, Gale crater, Mars. The stratigraphy consists of cross-stratified sandstone (Facies 1), planar-laminated sandstone (Facies 2), and planar-laminated mudstone (Facies 3). Facies 1 is composed of sandstone showing truncated sets of concave-curvilinear laminae stacked into cosets. Sets are estimated to be meter-to sub-meter-scale, consistent with low-height dunes. Thin stratigraphic intervals of Facies 1 and stacking patterns with Facies 2 and 3 support a wet aeolian dune interpretation. Meter-thick packages of planar-laminated sandstone (Facies 2) are interpreted to represent interfingering dune-interdune strata. Facies 3 consists of meter-thick packages of planar-laminated mudstone interpreted to represent lacustrine deposition with persistent standing water. Integration of geochemistry with each facies reveals some compositional control based on the depositional process. Models for source rock composition from Alpha Particle X-Ray Spectrometer measurements show that facies derived from a basaltic source. Alteration indices and geochemical trends provide evidence that moderate chemical weathering occurred before compositional changes due to diagenesis. Differences in wt% FeO(T) and TiO2 between facies are minimal, though trends point to sediment sorting in transport. Comparisons to terrestrial basaltic sedimentary systems indicate that the Hartmann’s Valley and Karasburg facies reflect deposition in an environment where diverse subaqueous and subaerial facies persisted adjacent to a long-lived body of water.