¹Liam S. T. McGovern, ¹Bruce L. A. Charlier, ¹Colin J. N. Wilson
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14278]
¹School of Geography, Environment and Earth Sciences, Victoria University of Wellington, Wellington, New Zealand
Published by arrangement with John Wiley & Sons

Stepwise acid leaching experiments were performed on the pre-rain CM2 fall Aguas Zarcas to interrogate release patterns and isolate fractions with isotopic anomalies. Acid leachates and a bulk sample were analyzed for elemental abundances via solution ICP-MS, and Sr and Ba isotopic compositions were measured using TIMS. Isotopic systematics reveal diverse values for the bulk sample and leachates, interpreted to reflect the Aguas Zarcas parent body history. Compared with the NBS987 standard, μ84Sr values for the bulk sample average + 90, while the leach fractions yield +326 to −2089, with the largest μ84Sr depletions in the strongest acid leachates. For Ba isotopes, the bulk sample shows resolvable depletions (μ values) in 130Ba (−210), 135Ba (−64), 137Ba (−73) and 138Ba (−89). Early leachates show positive anomalies in 130Ba (up to +2295), 132Ba, 135Ba, 137Ba, and 138Ba. In contrast, final leachates show strong depletions for the same nuclides (up to −60,000 ppm μ130Ba). The Sr and Ba isotopic anomalies found in the earlier leachates suggest that nucleosynthetic signatures were redistributed to more soluble phases during parent body alteration. Moreover, contrasting p-nuclide Sr and Ba nucleosynthetic anomalies suggest that presolar contributions came from a variety of nucleosynthetic sources, including possibly a rotating massive star undergoing a core-collapse supernova or an electron capture supernova.

¹Marie Kepp, ^1,2,3Lu Pan, ¹Jens Frydenvang, ¹Martin Bizzarro
Earth and Planetary Science Letters 648, 119082 Link to Article [https://doi.org/10.1016/j.epsl.2024.119082]
¹Centre for Star and Planet Formation, Globe Institute, University of Copenhagen, Copenhagen, Denmark
²School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, PR China
³Deep Space Exploration Laboratory, Hefei 230026, PR China
Copyright Elsevier

The Mars Science Laboratory has been investigating the central mound of Gale crater since 2012 and revealed evidence of silica enrichment in several locations, suggesting that the geologic processes related to the formation of hydrated silica could be widespread. A reanalysis of orbital data over Aeolis Mons indicates the existence of an extensive unit rich in hydrated silica. These silica-enriched deposits, found at the base of Aeolis Mons, span elevations from -4513 m to -3351 m. The mapped hydrated silica deposits are spatially adjacent to an erosion-resistant capping unit, previously mapped as the mound skirting unit, which lies beneath the terminal deposits from local canyons and valleys. We hypothesize that the hydrated silica-bearing unit precipitated from groundwater which migrated upwards or deposited as a volcaniclastic silica-rich layer which was rehydrated during the late-stage canyon and valley forming events. The silica-bearing unit beneath the capping unit is protected against erosion by younger fan-shaped deposits and became exposed only recently. The mineralogy and stratigraphic relations with Mount Sharp units imply that the aqueous activities leading to silica diagenesis were likely a basin-wide process that occurred long after the formation of lakes in Gale crater’s geological history and experienced limited water-rock interaction since then.

¹M. Brož,²P. Vernazza,^3,4M. Marsset,⁴F. E. DeMeo,⁴R. P. Binzel,¹D. Vokrouhlický,⁵D. Nesvorný
Nature 634, 566-571 Link to Article [DOI https://doi.org/10.1038/s41586-024-08006-7]
¹Charles University, Faculty of Mathematics and Physics, Institute of Astronomy, Prague, Czech Republic
²Aix Marseille University, CNRS, CNES, LAM, Institut Origines, Marseille, France
³European Southern Observatory (ESO), Santiago, Chile
⁴Department of Earth, Atmospheric and Planetary Sciences, MIT, Cambridge, MA, USA
⁵Department of Space Studies, Southwest Research Institute, Boulder, CO, USA

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^1,2M.Marsset et al. (>10)
Nature 634, 561-565 Link to Article [DOI https://doi.org/10.1038/s41586-024-08007-6]
¹European Southern Observatory (ESO), Santiago, Chile
²Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA

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¹David G. Burtt et al. (>10)
Proceedings of the National Academy of Sciences of the United States of America (PNAS) 121, e2321342121 Open Access Link to Article [https://doi.org/10.1073/pnas.232134212]
¹NASA Postdoctoral Fellow, Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771

Carbonate minerals are of particular interest in paleoenvironmental research as they are an integral part of the carbon and water cycles, both of which are relevant to habitability. Given that these cycles are less constrained on Mars than they are on Earth, the identification of carbonates has been a point of emphasis for rover missions. Here, we present carbon (δ13C) and oxygen (δ18O) isotope data from four carbonates encountered by the Curiosity rover within the Gale crater. The carbon isotope values range from 72 ± 2‰ to 110 ± 3‰ Vienna Pee Dee Belemnite while the oxygen isotope values span from 59 ± 4‰ to 91 ± 4‰ Vienna Standard Mean Ocean Water (1 SE uncertainties). Notably, these values are isotopically heavy (13C- and 18O-enriched) relative to nearly every other Martian material. The extreme isotopic difference between the carbonates and other carbon- and oxygen-rich reservoirs on Mars cannot be reconciled by standard equilibrium carbonate–CO2 fractionation, thus requiring an alternative process during or prior to carbonate formation. This paper explores two processes capable of contributing to the isotopic enrichments: 1) evaporative-driven Rayleigh distillation and 2) kinetic isotope effects related to cryogenic precipitation. In isolation, each process cannot reproduce the observed carbonate isotope values; however, a combination of these processes represents the most likely source for the extreme isotopic enrichments.

^1,2Bohao Chen,^2,3Xiao-Wen Yu,^4,5Yu-Yan Sara Zhao,^2,3Di-Sheng Zhou,^2,3Shuai-Yi Qu,^1,6Jiannan Zhao,^3,7Chao Qi,^2,5Xiongyao Li,^2,5Jianzhong Liu
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2023JE008250]
¹State Key Laboratory of Geological Process and Mineral Resources, Planetary Science Institute, School of Earth Sciences, China University of Geosciences, Wuhan, China
²Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
³College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
⁴Research Center for Planetary Science, College of Earth and Planetary Sciences, Chengdu University of Technology, Chengdu, China
⁵CAS Center for Excellence in Comparative Planetology, Hefei, China
⁶Key Laboratory of Geological Survey and Evaluation of Ministry of Education, China University of Geosciences, Wuhan, China
⁷Key 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 scarce carbonate record on the Martian surface is one of the fundamental unsolved issues for paleoclimate and environmental evolution. Whether carbonates first formed and then dissolved due to a transition in global environments or whether Mg–Fe carbonates never extensively formed due to geochemical kinetics thresholds remains unknown. In this study, we experimentally examined the preservation potential of siderite in Mars-relevant fluids, including ultrapure water, H2O2, NaClO4, NaClO3, NaCl, Na2SO4, NaHCO3, and Na2SiO3 solutions, at 277 K. The effects of the water/rock ratio at WR10 and WR100 on dissolution rates were also investigated. We found that siderite dissolution and subsequent oxidation and hydrolysis of leached Fe did not substantially acidify the solutions. The siderite dissolved relatively rapidly in the chloride and chlorate solutions and slowly in the silica or bicarbonate solutions. In a circum-neutral to slightly alkaline aqueous environment with oxidative species, the mobility of leached Fe was limited, leading to the formation of goethite or lepidocrocite, which clustered on the siderite surface. The longest lifetime of 1-mm siderite grains was found in the Na2SiO3 solution at WR100, which was estimated to range from 198 ka to 198 Ma. Water-limited, silica-rich, and oxidative aqueous environments benefit siderite preservation on the Martian surface. Our results support that the lack of voluminous siderite on Mars may be primarily due to the inhibition of its formation rather than alteration and dissolution after its presence, consistent with the recent detection of Mg–Fe carbonate at Gale Crater and Jezero Crater.

¹K. H. Joy,²N. Wang,¹J. F. Snape,¹A. Goodwin,¹J. F. Pernet-Fisher,³M. J. Whitehouse,²Y. Liu,²Y. T. Lin,⁴J. R. Darling,⁵P. Tar,¹R. Tartèse
Nature Astronomy (in Press) Open Access Link to Article [DOI https://doi.org/10.1038/s41550-024-02380-y]
¹Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
²Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
³Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden
⁴School of the Environment, Geography and Geosciences, University of Portsmouth, Portsmouth, UK
⁵Previously at the School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK

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^1,2Sen Hu, ^2,3Mahesh Anand, ²Ian A. Franchi, ²Xuchao Zhao, ^2,4Alice Stephant, ⁵Magali Bonifacie, ^1,6Huicun He, ¹Wei Yang, ¹Jialong Hao, ¹Yangting Lin
Earth and Planetary Science Letters 648, 119072 Open Access Link to Article [https://doi.org/10.1016/j.epsl.2024.119072]
¹Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
²School of Physics Sciences, The Open University, Milton Keynes MK7 6AA, UK
³Department of Earth Sciences, The Natural History Museum, London, SW7 5BD, UK
⁴Istituto di Astrofisica e Planetologia Spaziali -INAF, Roma, Italy
⁵Institut de Physique du Globe de Paris, Université de Paris, CNRS, 75005 Paris, France
⁶College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Copyright Elsevier

The chassignites and nakhlites could have co-magmatic origin but display distinct hydrogen and chlorine isotopic compositions, indicating that they may have experienced distinct hydrothermal activities on Mars. However, the details are not yet fully understood. Here, we performed H and Cl isotopic investigations on hydrous minerals (kaersutite and apatite) and glass-bearing melt inclusions from chassignite NWA 2737 to unravel the details of the hydrothermal events experienced by chassignites on Mars. Our results demonstrate that at least two hydrothermal events on Mars have been recorded in NWA 2737. A D- and 37Cl-rich martian crustal/underground fluid was added to the parent magma of NWA 2737 prior to the entrapment of melt inclusions and later interaction of the parent rock with a D-poor fluid, probably deriving from magma degassing. The notable high-δD values (up to 6239‰) of kaersutite in NWA 2737 are comparable with those recorded in younger shergottites, suggesting that the martian exchangeable water reservoir has retained a nearly constant δD value over the past 1.3

¹Mihail P. Petkov, ²Ryan P. Wilkerson, ³Gerald E. Voecks, ⁴Douglas L. Rickman, ⁵Jennifer E. Edmunson, ⁵Michael R. Effinger
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2024.105982]
¹SuprAEther LLC, La Crescenta, CA, 91214, USA
²Sigma-1: Fabrication Manufacturing Science, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
³NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA
⁴Jacobs Engineering, Inc., Huntsville, AL, 35812, USA
⁵NASA Marshall Space Flight Center, Huntsville, AL, 35812, USA

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^1,2M. C. Nottingham,^1,3,4N. M. Curran,¹J. Pernet-Fisher,¹R. Burgess,¹I. A. Crawford,¹J. D. Gilmour,¹R. Tartèse,¹K. H. Joy
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14244]
¹Department of Earth and Environmental Sciences, University of Manchester, Manchester, UK
²School of Geographical and Earth Sciences, Molema Building, University of Glasgow, Glasgow, G12 8QQ UK
³NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
⁴CRESST2/Catholic University of America, Washington, DC, USA
⁵School of Natural Sciences, Birkbeck College, University of London, London, UK
Published by arrangement with John Wiley & Sons

The Apollo 16 regolith breccia sample suite provides a record of lunar regolith formation from the basin-forming epoch (~3.9 Ga) through to a time of declining impactor flux (~2 Ga). These rocks have been characterized into three groups: the “ancient,” “young,” and “soil-like” regolith breccias on the basis of their petrographic characteristics, and, in the case of the “ancient” and “young” regolith breccias, noble gas inventory. This study investigates the as-yet unexamined noble gas records of the “soil-like” regolith breccias to understand more recent regolith evolution processes that occurred at the Apollo 16 landing site. The range of gas concentrations measured for each noble gas in these samples is comparable to those previously reported for the local Apollo 16 soils. The “soil-like” regolith breccias were found to be more gas rich than the gas poor “young” and “ancient” regolith breccias, consistent with them having formed from comparatively mature soil(s). Our results further confirm the scientific value of lunar regolith breccias and bulk regolith samples as probes of the impact history and the space environment of the lunar surface across a wide range of time.