¹B. Sutter,¹P. D. Archer,²P. B. Niles,²D. W. Ming,³D. Hamara,³W. V. Boynton
Journalof Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2024JE008335]
¹Jacobs/JETSII, NASA Johnson Space Center, Houston, TX, USA
²NASA Johnson Space Center, Houston, TX, USA
³Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
Published by arrangement with John Wiley & Sons

The Thermal Evolved Gas Analyzer (TEGA) analysis of surface and icy subsurface Phoenix landing site soils consisted of low (300–700°C) and high (>700°C) temperature CO2 evolutions that were attributed to organic carbon (83–1,484 μgC/g) and Ca-rich carbonate (1.1–2.6 wt.%). Total carbon abundances ranged from 1,143 to 4,905 µgC/g, which is the highest soil carbon concentration so far detected on Mars. Low temperature CO2 was attributed to oxidized organic C (e.g., oxalates, acetates), while hydrocarbon combustion was indicated in two soils by the detection of coevolved CO2 and O2 (perchlorate). Combustion reactions may have prevented the detection of hydrocarbon masses in the Phoenix landing site soils. Organic C was likely derived from meteoritic and igneous/hydrothermal sources, but microbiological sources cannot be excluded. CO2 evolved at high temperatures was consistent with Ca-rich carbonate along with possible minor contributions from macromolecular organic carbon and mineral/glass vesicle CO2. Carbon detected in the Phoenix landing site soil and other landing site soils and sands (e.g., Gale/Jezero craters) would be consistent with global organic C and carbonate in soils and sand across Mars. However, oxidizing water thin films derived from the near-surface ice in the Phoenix soils favor Ca-carbonate over Fe-carbonate, which is likely more stable in the ice-free regions of Mars (e.g., Gale/Jezero craters). The global carbon budget on Mars inferred from these results emphasizes that Mars Sample Return should yield carbon bearing soil/rock that would allow the identification of the origin of carbon and any possible connections to ancient martian microbiology.

¹Sanchez, Juan A.,²Reddy, Vishnu,³Thirouin, Audrey,⁴Bottke, William F.,³Kareta, Theodore,⁵De Florio, Mario,⁶Sharkey, Benjamin N. L.,²Battle, Adam,²Cantillo, David C.,¹Pearson, Neil
The Planetary Science Journal 5, 131 Open Access Link to Article [DOI 10.3847/PSJ/ad445f]
¹Planetary Science Institute, 1700 East Fort Lowell Road, Tucson, 85719, AZ, United States
²Lunar and Planetary Laboratory, University of Arizona, 1629 East University Boulevard, Tucson, 85721-0092, AZ, United States
³Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, 86004, AZ, United States
⁴Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, 80302, CO, United States
⁵Division of Applied Mathematics, Brown University, 170 Hope Street, Providence, 02906, RI, United States
⁶Department of Astronomy, University of Maryl, 4296 Stadium Drive PSC (Building 415), Room 1113, College Park, 20742-2421, MD, United States

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

¹Y.Y. He et al. (>10)
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.09.035]
¹Institut de Minéralogie, Physique des Matériaux et Cosmochimie, IMPMC, Muséum
Copyright Elsevier

Carbonaceous chondrites contain amino acids, with variable abundances and isotope compositions between and within carbonaceous chondrites. The parent body processes, and the presence of clay minerals may explain those differences. Here, we experimentally investigate the evolution of 6 amino acids (glycine, β-alanine, α-alanine, 2-aminoisobutyric acid, γ-aminobutyric acid, and isovaline) exposed to hydrothermal conditions in the presence or absence of silicates. We determined the chemical nature and isotopic composition of the organic compounds of the soluble and solid fractions of the residues using X-ray diffraction, spectroscopy, and mass-spectrometry methods. Glycine and α-alanine exhibit a rather high stability, which is consistent with the measured abundances of α-alanine and glycine in chondrites having experienced various degrees of aqueous alteration. In the meantime, the evolution of β-alanine under hydrothermal conditions leads to the formation of a new compound, which likely results from the decarboxylation and deamination of β-alanine followed by recombination. More than 95 % of γ-ABA was transformed into 2-pyrrolidione though self-cyclization during the aqueous alteration. The solid residues of the experiments conducted in the presence of clay minerals contain organic material, with abundances varying depending on the amino acid used for the experiments (TOC isovaline > 2-aminoisobutyric acid > γ-aminobutyric acid > glycine > α-alanine > β-alanine). Clay minerals thus preferentially trap branched amino acids over chained amino acids, likely within their interlayer spaces as suggested by XRD data. The δ¹³C values of amino acids have not changed significantly during the experiments, even with the presence of silicates. Thus, the δ¹³C values of amino acids reported in CR and CM chondrites likely relate to synthetic conditions or the origin of their precursors (i.e. inherited from the pre-accretion processes).

¹Hitoshi Miura
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2024.116317]
¹Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, 467-8501, Aichi, Japan
Copyright Elsevier

In this study, we propose a novel numerical method to simulate the growth dynamics of an olivine single crystal within an isolated, multicomponent silicate droplet. We aimed to theoretically replicate the solidification textures observed in chondrules. The method leverages the phase-field model, a well-established framework for simulating alloy solidification. This approach enables the calculation of the solidification process within the ternary MgO–FeO–SiO
system. Furthermore, the model incorporates the anisotropic characteristics of interface free energy and growth kinetics inherent to the crystal structure. Here we investigated an anisotropy model capable of reproducing the experimentally observed dependence of the growth patterns of the olivine single crystal on the degree of supercooling under the constraints of two-dimensional modeling. By independently adjusting the degree of anisotropies of interface free energy and growth kinetics, we successfully achieved the qualitative replication of diverse olivine crystal morphologies, ranging from polyhedral shapes at low supercooling to elongated, needle-like structures at high supercooling. This computationally driven method offers a unique and groundbreaking approach for theoretically reproducing the solidification textures of chondrules.

¹Yang Liu,²Chi Ma
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2024JE008444]
¹Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
²Division of Geology and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
Published by arrangement with John Wiley & Sons

Identification of the mineral species of vapor condensates on the surface of lunar pyroclastic beads, formed during the flights of beads in the lunar volcanic plume, helps to constrain the physical and chemical conditions of the lunar volcanic plume. We conducted nanomineralogy studies of vapor condensates on the surface of pristine black beads from a clod that was extracted from the recently opened Apollo drive tube 73001. This drive tube had been sealed under vacuum since its collection on the Moon and thus represents the most pristine sample in allocatable Apollo collection. Vapor condensates observed on the surface include patches made of ZnS nanocrystals and possible rare scattered NaCl nanocrystals. ZnS nanocrystals were previously found on Apollo 15 green and yellow beads, but NaCl nanocrystals are unique to black beads. Both ZnS and NaCl nanocrystals are absent in Apollo 17 74220 orange beads. Although orange and black beads are of similar chemistry, black beads in the clod 73001, 226 could form from a different environment.

¹Elias N. Mansbach et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2024JE008505]
¹Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
Published by arrangement with John Wiley & Sons

Although Mars today does not have a core dynamo, magnetizations in the Martian crust and in meteorites suggest a magnetic field was present prior to 3.7 billion years (Ga) ago. However, the lack of ancient, oriented Martian bedrock samples available on Earth has prevented accurate estimates of the dynamo’s intensity, lifetime, and direction. Constraining the nature and lifetime of the dynamo are vital to understanding the evolution of the Martian interior and the potential habitability of the planet. The Perseverance rover, which is exploring Jezero crater, is providing an unprecedented opportunity to address this gap by acquiring absolutely oriented bedrock samples with estimated ages from ∼2.3 to >4.1 Ga. As a first step in establishing whether these samples could contain records of Martian paleomagnetism, it is important to determine their ferromagnetic mineralogy, the grain sizes of the phases, and the forms of any natural remanent magnetization. Here, we synthesize data from various Perseverance instruments to achieve those goals and discuss the implications for future laboratory paleomagnetic analyses. Using the rover’s instrument payload, we find that cored samples likely contain iron oxides enriched in Cr and Ti. The relative proportions of Fe, Ti, and Cr indicate that the phases may be titanomagnetite or Fe-Ti-Cr spinels that are ferromagnetic at room temperature, but we cannot rule out the presence of non-ferromagnetic ulvöspinel, ilmenite, and chromite due to signal mixing. Importantly, the inferred abundance of iron oxides in the samples suggests that even <1 mm-sized samples will be easily measurable by present-day magnetometers.

¹Himela Moitra,^1,2Sumit Pathak,³Aditya K. Dagar,³R. P. Rajasekhar,^1,3Satadru Bhattacharya,¹Moumita Akuria,¹Saibal Gupta
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE008206]
¹Department of Geology & Geophysics, Indian Institute of Technology Kharagpur, Kharagpur, WB, India
²Department of Geology, Faculty of Applied Sciences, Parul University, Vadodara, GJ, India
³Planetary Sciences Division, Space Applications Centre, Indian Space Research Organisation, Ahmedabad, GJ, India
Published by arramgement with John Wiley & Sons

Silicic lithologies on planetary surfaces indicate magmatic evolutionary processes in their interiors. The Wolf crater complex within Mare Nubium on the Moon is one such silicic construct associated with a high thorium anomaly. This study integrates morphological, compositional, chronological and gravity anomaly analyses of high-resolution data from various lunar missions to establish this construct as a silicic volcanic caldera. Lobate flows with steeply sloping fronts indicate that the crater rims comprise high-viscosity silicic lavas, while the structurally controlled inner crater walls suggest caldera collapse triggered by magma depletion. In the crater rims, low Christiansen Feature position values reaffirm the presence of silicic lithologies, consistent with the low gravity anomaly signature beneath the complex, while spectroscopic data reveal low mafic mineral abundances and negligible hydration features. Chronological analyses yield silicic volcanism ages coeval with surrounding mare basalts (3.8–3.6 Ga), while intra-caldera basalts have 2.36–2.02 Ga ages, indicating prolonged magmatism in this region. Melting of suitable crustal protoliths like alkali gabbronorite/monzogabbro/troctolite by basaltic underplating is inferred to have generated silicic magmas that formed the Wolf volcanic complex, instead of basaltic magma fractionation or silicate-liquid immiscibility processes. Large impacts during the Late Heavy Bombardment may have enhanced partial melting of the mantle and created crustal fractures that facilitated the ascent of viscous silicic melts through the lunar crust. Contemporaneous existence of suitable protoliths and adequate crustal pathways for magma ascent may have controlled silicic volcanism on the Moon, and can explain the sporadic occurrence and overlapping ages of the lunar silicic constructs.

¹Seamus L. Anderson et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14268]
¹Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia
Published by arrangement with John Wiley & Sons

Over the Nullarbor Plain in South Australia, the Desert Fireball Network detected a fireball on the night of June 1, 2019 (7:30 pm local time), and 6 weeks later recovered a single meteorite (42 g) named Arpu Kuilpu. This meteorite was then distributed to a consortium of collaborating institutions to be measured and analyzed by a number of methodologies including SEM-EDS, EPMA, ICP-MS, gamma-ray spectrometry, ideal gas pycnometry, magnetic susceptibility measurement, μCT, optical microscopy, and accelerator and noble gas mass spectrometry techniques. These analyses revealed that Arpu Kuilpu is an unbrecciated H5 ordinary chondrite, with minimal weathering (W0-1) and minimal shock (S2). The olivine and pyroxene mineral compositions (in mole%) are Fa: 19.2 ± 0.2 and Fs: 16.8 ± 0.2, further supporting the H5 type and class. The measured oxygen isotopes are also consistent with an H chondrite (δ17O‰ = 2.904 ± 0.177; δ18O‰ = 4.163 ± 0.336; Δ17O‰ = 0.740 ± 0.002). Ideal gas pycnometry measured bulk and grain densities of 3.66 ± 0.02 and 3.77 ± 0.02 g cm−3, respectively, yielding a porosity of 3.0% ± 0.7. The magnetic susceptibility of this meteorite is log χ = 5.16 ± 0.08. The most recent impact-related heating event experienced by Arpu Kuilpu was measured by 40Ar/39Ar chronology to be 4467 ± 16 Ma, while the cosmic ray exposure age is estimated to be between 6 and 8 Ma. The noble gas isotopes, radionuclides, and fireball observations all indicate that Arpu Kuilpu’s meteoroid was quite small (maximum radius of 10 cm, though more likely between 1 and 5 cm). Although this meteorite is a rather ordinary ordinary chondrite, its prior orbit resembled that of a Jupiter Family Comet (JFC) further lending support to the assertion that many cm- to m-sized objects on JFC orbits are asteroidal rather than cometary in origin.

¹Laura Schaefer,²Kaveh Pahlevan,³Linda T. Elkins-Tanton
Journal of Geophysical Research (Planets) Link to Article [https://doi.org/10.1029/2023JE008262]
¹Department of Earth and Planetary Sciences, Stanford University, Stanford, CA, USA
²Carl Sagan Center, SETI Institute, Mountain View, CA, USA
³School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
Published by arrangement with John Wiley & Sons

Magma ocean crystallization models that track fO2 evolution can reproduce the D/H ratios of both the Earth and Mars without the need for exogenous processes. Fractional crystallization leads to compositional evolution of the bulk oxide components. Recent work suggests that metal-saturated magma oceans may contain near-present-day Fe3+ concentrations. We model the fractional crystallization of Earth and Mars, including Fe2+ and Fe3+ as separate components. We calculate Fe3+ partition coefficients for lower mantle minerals and compare the results of fractional crystallization for both Earth and Mars. We calculate oxygen fugacity (fO2) at the surface as the systems evolve and compare them to constraints on the fO2 of the last magma ocean atmosphere from D/H ratios, both with and without metal saturation. For Earth, we find that Fe3+ likely behaves incompatibly in the lower mantle in order to match the D/H constraint for whole mantle models, but shallow magma ocean models also provide reasonable matches. Disproportionation in whole mantle magma oceans likely overpredicts the amount of Fe3+ and metal that form or require subsequent reduction to return to present-day values. For Mars, we cannot match the D/H constraints on last fO2 unless the magma ocean begins with <50% of the predicted Fe3+, but better match the present day mantle redox. We show that Fe3+ partitioning has a measurable effect on magma ocean redox, and that it evolves throughout the magma ocean’s lifetime. We highlight the need for additional experimental constraints on ferric iron mineral/melt partitioning and more thermodynamic data for the Fe-disproportionation reaction.

¹A. Nathues,¹M. Hoffmann,¹R. Sarkar,¹P. Singh,¹J. Hernandez,²J. H. Pasckert,²N. Schmedemann,³G. Thangjam,⁴E. Cloutis,¹K. Mengel,¹M. Coutelier
Journal og Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE008150]
¹Max Planck Institute for Solar System Research, Goettingen, Germany
²Institut für Planetologie, Universität Münster, Münster, Germany
³School of Earth and Planetary Sciences, National Institute of Science Education and Research, NISER, HBNI, Khurda, Odisha, India
⁴University of Winnipeg, Winnipeg, MB, Canada
Published by arrangement with John Wiley & Sons

Ceres is a partially differentiated dwarf planet located in the main asteroid belt. Consus crater (diameter ∼64 km) is one of the oldest impact features (∼450 Ma) on the Cerean surface that surprisingly still shows a large variety of color lithologies, including exposures of bright material, which are thought to be brine residues. Here, we present new results that help in understanding the structure and composition of the Cerean crust. These results were deduced by using newly processed Dawn Framing Camera (FC) color imagery and FC clear filter images combined with infrared spectral data of Dawn’s Visible and Infrared Spectrometer (VIR). Consus exhibits a variety of color lithologies, which we describe in detail. Interestingly, we found three spectrally different types of bright material exposed by a large old crater on Consus’ floor. One of these, the yellowish bright material (Nathues et al., 2023, https://www.hou.usra.edu/meetings/lpsc2023/pdf/1073.pdf) and its modification, shows spectral signatures consistent with ammonium-enriched smectites. We hypothesize that the ammonium in these smectites stems from contact with ascending brines, originating from a low-lying former brine ocean that has been enriched in ammonium during the differentiation and freezing process of the Cerean crust. This enrichment is mainly due to ammonium uptake by sheet silicates. If such an ammonium enrichment occurred over long-time scales on a global scale, this process may explain the vast presence of ammonium on the Cerean surface. Therefore, an outer solar system origin of Ceres is possibly not needed to explain the global presence of ammonium.