^1,2,3Sheng Gou et al. (>10)
Earth and Planetary Science Letters 648, 119091 Link to Article [https://doi.org/10.1016/j.epsl.2024.119091]
¹Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
²State Key Laboratory of Remote Sensing Science, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100101, China
³State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, 999078, China
Copyright Elsevier

China’s Chang’e-6 (CE6) sample return mission targeted the southern part of the Apollo basin inside the South Pole-Aitken (SPA) basin on the lunar farside. The spectrally peculiar mare basalts in the CE6 landing area had undergone complex evolution: (1) At least three mare floodings with low- to intermediate-titanium (Ti) contents and a total volume of > 798 km3 occurred during the Imbrian and Eratosthenian periods; (2) The scales of basalt eruption decreased with time, and nine wrinkle ridges (WRs) formed during different stages of floodings; (3) Exotic non-mare materials at the CE6 sampling site might be chiefly from noritic Chaffee S crater (∼16.6 cm-thick) and anorthositic Vavilov crater (∼1.7 cm-thick). (4) Impact gardening would mix local low/intermediate-Ti basalts and exotic non-mare materials. After analyzing the local basalt-dominant samples collected by the CE6 probe with sophisticated instruments in the terrestrial laboratories, a series of lunar scientific problems would be addressed definitely, for example, the ages and compositions of the mare basalts, the evolution of the low- and intermediate-Ti basalts, and the effects of solar wind on the lunar regolith. In addition, if the returned samples contain exotic impact melts and ejecta of both the Apollo and SPA basins, analyses on these non-mare materials would help to constrain the timing of the Apollo and SPA impact events, the extent and composition of the proposed (differentiated) SPA melt pool, and even the compositions of the lunar lower crust/upper mantle. Addressing these fundamental problems would be a significant contribution to the lunar science community.

¹Nadja Drabon,¹Andrew H. Knoll,²Donald R. Lowe,³Stefano M. Bernasconi, ¹Alec R. Brenner,²David A. Mucciarone
Proceedings of the National Academy of Science of the United States of America (PNAS) 121, e2408721121 Open Access Link to Article [https://doi.org/10.1073/pnas.2408721121]
¹Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
²Department of Earth and Planetary Sciences, Stanford University, Stanford, CA 94305
³Department of Earth Sciences, ETH Zürich, Zürich 8092, Switzerland

Large meteorite impacts must have strongly affected the habitability of the early Earth. Rocks of the Archean Eon record at least 16 major impact events, involving bolides larger than 10 km in diameter. These impacts probably had severe, albeit temporary, consequences for surface environments. However, their effect on early life is not well understood. Here, we analyze the sedimentology, petrography, and carbon isotope geochemistry of sedimentary rocks across the S2 impact event (37 to 58 km carbonaceous chondrite) forming part of the 3.26 Ga Fig Tree Group, South Africa, to evaluate its environmental effects and biological consequences. The impact initiated 1) a giant tsunami that mixed Fe2+-rich deep waters into the Fe2+-poor shallow waters and washed debris into coastal areas, 2) heating that caused partial evaporation of surface ocean waters and likely a short-term increase in weathering and erosion on land, and 3) injection of P from vaporization of the S2 bolide. Strata immediately above the S2 impact event contain abundant siderites, which are associated with organic matter and exhibit light and variable δ13Ccarb values. This is consistent with microbial iron cycling in the wake of the impact event. Thus, the S2 impact likely had regional, if not global, positive and negative effects on life. The tsunami, atmospheric heating, and darkness would likely have decimated phototrophic microbes in the shallow water column. However, the biosphere likely recovered rapidly, and, in the medium term, the increase in nutrients and iron likely facilitated microbial blooms, especially of iron-cycling microbes.

¹Derek W. G. Sears,¹Alexander Sehlke,²Harrison H. Schmitt, the ANGSA Science Team
Journal of Geophysical Research (Planets) Open Access Link to Article [https://doi.org/10.1029/2024JE008358]
¹NASA Ames Research Center/Bay Area Environmental Research Institute, Moffett Field, CA, USA
²Department of Engineering Physics, University of Wisconsin-Madison, Albuquerque, NM, USA
Published by arrangement with John Wiley & Sons

By placing Apollo 17 regolith samples in a freezer, and storing an equivalent set at room temperature, NASA effectively performed a 50-year experiment in the kinetics of natural thermoluminescence (TL) of the lunar regolith. We have performed a detailed analysis of the TL characteristics of four regolith samples: a sunlit sample near the landing site (70180), a sample 3 m deep near the landing site (70001), a sample partially shaded by a boulder (72320), and a sample completely shaded by a boulder (76240). We find evidence for a total of eight discrete TL peaks, five apparent in curves for samples in the natural state and seven in samples irradiated in the laboratory at room temperature. For each peak, we suggest values for peak temperatures and the kinetic parameters E (activation energy, i.e. “trap depth,” eV) and s (Arrhenius factor, s−1). The lowest natural TL peak in the continuously shaded sample 76240 dropped in intensity by 60 ± 10% (1976 vs. present room temperature samples) and 43 ± 8% (freezer vs. room temperature samples) over the 50-year storage period, while sunlit and partially shaded samples (70001, 70180, 72321, 72320) showed no change. These results are consistent with the E and s parameters we determined. The large number of peaks, and the appearance of additional peaks after irradiation at room temperature, and literature data, suggest that glow curve peaks are present in lunar regolith at ∼100 K and their intensity can be used to determine temperature and storage time. Thus, a TL instrument on the Moon could be used to prospect for micro-cold traps capable of the storage of water and other volatiles.

¹Mitsuru Ebihara, ²Naoki Shirai, ³Takahito Osawa, ⁴Akira Yamaguchi
Geochimica Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.10.026]
¹Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
²Department of Chemistry, Kanagawa University, Yokohama, Kanagawa 221-0802, Japan
³Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
⁴National Institute of Polar Research, Tachikawa, Tokyo 190-8518, Japan
Copyright Elsevier

Fifteen elements, including most of the major elements, were quantified using neutron-induced prompt gamma-ray analysis for five Antarctic carbonaceous chondrites with CI affinities and seven with CM affinities. Common among the twelve meteorites is the depletion of volatile elements H and chlorine, showing a positive correlation and being depleted compared to non-Antarctic CI levels. This depletion is not thought to have occurred after the fall on Antarctica, but to have been caused by thermal metamorphism on the parent body. Among the meteorites analyzed in this study, six meteorites (Y-86029, Y 980115, Y-82162 (with CI affinities), Y-86720, Y-86789, B-7904 (with CM affinities)) have previously been proposed to constitute a new meteorite group, the Yamato-type (CY), based on their oxygen isotopic compositions and petrological features. The elemental compositional characteristics of the remaining six meteorites analyzed in this study, Y-86737 and Y 980134 (with CI affinities), and Y-86770, Y-86771, Y-86772 and Y-86773 (with CM affinities), suggest that these meteorites are all classified into the same chemical group CY. Based on the abundance of moderately volatile elements Mn and S, the twelve meteorites can be divided into two groups: one with levels similar to non-Antarctic CI and the other with intermediate levels between CI and CM. These results suggest that CY chondrites originate from two distinct parent bodies. To facilitate further discussions on CY chondrites, we propose naming the groups with compositions close to CI and CM as CYi and CYm, respectively.

¹J. L. MacArthur,¹K. H. Joy,¹R. H. Jones,²T. A. Harvey,³N. V. Almeida
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14273]
¹Department of Earth and Environmental Sciences, University of Manchester, Manchester, UK
²The Geological Society of London, Burlington House, London, UK
³Planetary Materials Group, Natural History Museum, London, UK
Published by arrangement with John Wiley & Sons

The field of advanced curation is important for existing astromaterials collections, which includes samples returned by space missions, and meteorites and cosmic dust samples that have been recovered from here on Earth. In order to maximize the scientific return of the samples, contamination needs to be minimized at all stages of sample collection, preliminary examination, classification, and curation. Utilizing best practice methods, a detailed acquisition and curation plan was implemented during the UK’s first two expeditions to collect Antarctic meteorites from two new blue icefields, Hutchison Icefields and Outer Recovery Icefields. This article documents the design and execution of the procedures used during the project’s curation and classification processes. It describes two case studies showing the processes applied to the recovered meteorites, and reviews our experiences and lessons learned for the future.

^1,2Kohei Fukuda,^3,4Yuki Hibiya,⁵Craig R. Kastelle,⁴Katsuhiko Suzuki,⁶Tsuyoshi Iizuka,⁷Katsuyuki Yamashita,⁵Thomas E. Helser,¹Noriko T. Kita
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14276]
¹WiscSIMS, Department of Geoscience, University of Wisconsin-Madison, Madison, Wisconsin, USA
²Forefront Research Center, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
³Research Center for Advanced Science and Technology, Graduate School of Science, The University of Tokyo, Meguro, Tokyo, Japan
⁴Submarine Resources Research Center, Japan Agency for Marine-Earth Science Technology, Yokosuka, Kanagawa, Japan
⁵National Oceanic and Atmospheric Administration, Seattle, Washington, USA
⁶Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo, Japan
⁷Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, Okayama, Japan
Published by arrangement with John Wiley & Sons

Understanding the material transport and mixing processes in the Solar protoplanetary disk provides important constraints on the origin of chemical and isotopic diversities of our planets. The limited extent of radial transport and mixing between the inner and outer Solar System has been suggested based on a fundamental isotopic dichotomy between non-carbonaceous (NC) and carbonaceous (CC) meteorite groups. The limited transport and mixing could be further tested by tracing the formation regions of individual meteoritic components, such as Ca-Al-rich inclusions (CAIs) and chondrules. Here, we show further evidence for the outward transport of CAIs and chondrules from the inner and subsequent thermal processing in the outer region of the protoplanetary disk based on the petrography and combined Cr-Ti-O isotope systematics of chondrules from the Vigarano-like (CV) carbonaceous chondrite Allende. One chondrule studied consists of an olivine core that exhibits NC-like Ti and O, but CC-like Cr isotopic signatures, which is enclosed by a pyroxene igneous rim with CC-like O isotope ratios. These observations indicate that the olivine core formed in the inner Solar System. The olivine core then migrated into the outer Solar System and experienced nebular thermal processing that generated the pyroxene igneous rim. The nebular thermal processing would result in Cr isotope exchange between the olivine core and CC-like materials, but secondary alteration effects on the parent body are also responsible for the CC-like Cr isotope signature. By combining previously reported Cr-Ti-O isotope systematics of CV chondrules, we show that some CV chondrules larger than ~1 mm would have formed in the inner Solar System. The accretion of the millimeter-sized, inner Solar System solids onto the CV carbonaceous chondrite parent body would require their very early migration into the outer Solar System within the first 1 million years after the Solar System formation.

¹Robert B. Reid,¹Molly C. McCanta,²Justin Filiberto,³Allan H. Treiman,²Lindsay Keller,⁴Malcolm Rutherford
Journal of Geophysical Resarch (Planets) (in Press) Link to Article [https://doi.org/10.1029/2024JE008485]
¹Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN, USA
²NASA Johnson Space Center, Houston, TX, USA
³Lunar and Planetary Institute, Houston, TX, USA
⁴Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI, USA
Published by arrangement with John Wiley & Sons

Venus’ surface and interior dynamics remain largely unconstrained, due in great part to the major obstacles to exploration imposed by its 470°C, 90 bar surface conditions and its thick, opaque atmosphere. Flyby and orbiter-based thermal emission data provide opportunities to characterize the surface composition of Venus. However, robust interpretations of such data depend on understanding interactions between the planet’s surface basaltic rocks and its caustic carbon dioxide (CO2)-dominant atmosphere, containing trace amounts of sulfur dioxide (SO2). Several studies, using remote sensing, thermodynamic modeling, and laboratory experiments, have placed constraints on basaltic alteration mineralogy and rates. However, constraints on the effects of SO2-bearing reactions on basalts with diverse compositions remain incomplete. Here, we present new data from a series of gas-solid reaction experiments, in which samples of two basalt compositions were reacted in an SO2-bearing CO2 atmosphere, at relevant Venus temperatures, pressure, and oxygen fugacity. Reacted specimens were analyzed by scanning electron microscopy and scanning transmission electron microscopy using sample cross-sections produced with focused ion beam milling. Surface alteration products were characterized, and their abundances estimated; subsurface cation concentrations were mapped to show the depth of alteration. We demonstrate that the initial development of reaction products progresses rapidly over the course of 30-day runs. Alkaline basalt samples are coated by Na-sulfate (likely thenardite, Na2SO4) and amorphous calcium carbonate (CaCO3) alteration products, and tholeiitic basalt samples are primarily covered by anhydrite (CaSO4), Fe-oxide (FexOy: likely magnetite, Fe3O4), and other minor phases. These mineralogies differ from previous experiments in CO2-only atmospheres.

¹Y. Wu,^1,2Z. Xiao,³Y. Wu,⁴L. Pan,¹P. Yan,^2,6S. Liao,¹Q. Pan,⁷S. Li,^2,6Y. Li,^2,6W. Hsu
Journal of Geophysical Research (Planets) (In Press) Link to Article [https://doi.org/10.1029/2024JE008412]
¹Planetary Environmental and Astrobiological Research Laboratory, School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai, China
²CAS Center for Excellence in Comparative Planetology, Chinese Academy of Sciences, Hefei, China
³Analysis and Test Center, Guangdong University of Technology, Guangzhou, China
⁴School of Earth Sciences and Engineering, Sun Yat-sen University, Zhuhai, China
⁵Planetary Environmental and Astrobiological Research Laboratory, School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai, China
⁶Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, China
⁷Astronomical Research Center, Shanghai Science & Technology Museum, Shanghai, China
Published by arrangement with John Wiley & Sons

Apatites record crucial information on the origin, composition, and chemical evolution of volatiles on terrestrial planets. As a martian intrusive rock, the gabbroic shergottite Northwest Africa (NWA) 13581 provides key information on the volatile evolution related to magmatic processes in the interior, shedding light on the intricate volatile circulation on Mars. The textural and chemical characteristics of the phosphates in NWA 13581 indicate a complex formation history involving fractional crystallization, degassing, and fluid interaction. Degassing of the NWA 13581 parent melt is capable of exsolving chlorine-rich fluids, resulting in the formation of notably fluorine-rich apatite with a high x-site occupancy of fluorine up to 90%. The degassed/exsolved volatile-rich fluids could subsequently continue to migrate and interact with surrounding magmatic suites, leading to highly heterogeneous compositions of active fluids. The crystallization of apatite is initiated by the interaction of fluids with merrillite at the late stage of the magmatic process, leading to the formation of phosphate intergrowths. Influenced by the composition and chemical evolution of volatiles in fluids and melts, apatite exhibits notable variability in chlorine compositions both within individual grains and among different grains. Moreover, the presence of magnetite associated with phosphate intergrowth highlights the transportation of metallic components in addition to volatiles from deep layers to shallower depths or to the surface of Mars. This process, which is observed in young shergottites, indicates the persistent presence of hydrothermal systems until recent geological periods, contributing to the generation and circulation of volatiles within the martian interior and on the surface.

¹Juulia-Gabrielle Moreau,¹Argo Jõeleht,²Aleksandra N. Stojic,³Christopher Hamann,³Felix E. D. Kaufmann,¹Peeter Somelar,¹Jüri Plado,⁴Satu Hietala,^5,6Tomas Kohout
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14274]
¹Department of Geology, Institute of Ecology and Earth Science, University of Tartu, Tartu, Estonia
²Institut für Planetologie, Westfälische Wilhelms Universität Münster, Münster, Germany
³Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany
⁴Geological Survey of Finland, Kuopio, Finland
⁵School of Electrical Engineering, Aalto University, Espoo, Finland
⁶Institute of Geology of the Czech Academy of Sciences, Prague 6, Czech Republic
Published by arrangement with John Wiley & Sons

Iron sulfide and metal melt veins in chondritic materials are associated with advanced stages of dynamic shock. The shock-induced residual temperatures liquefy the sulfide component and enable melt distribution. However, the distribution mechanism is not yet fully understood. Capillary forces are proposed as agents of melt distribution; yet, no laboratory experiments were conducted to assess the role that capillary forces play in the redistribution of iron sulfide in post-shock conditions. To investigate this further, we conducted thermal experiments under reducing conditions (N2(g)) using dunitic fragments, suitable chondritic analog materials that were doped with synthesized troilite (stoichiometric exact FeS). We observed extensive iron sulfide (troilite) migration that partially resembles that of ordinary chondrites, without the additional influence of shock pressure-induced fracturing. The iron sulfide melt infiltrated grain boundaries and pre-existing fractures that darkened the analog material pervasively. We also observed that the iron sulfide melt, which mobilized into grain boundaries, got systematically enriched in Ni from the surrounding host olivine. Consequently, FeNi metal fractionated from the melt in several places. Our results indicate that capillary forces majorly contribute to melt migration in the heated post-shock environment.

^1,2Mingyeong Lee,¹Minsup Jeong,^1,2Young-Jun Choi
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2024JE008406]
¹Korea Astronomy and Space Science Institute, Daejeon, Republic of Korea
²University of Science and Technology, Daejeon, Republic of Korea
Published by arrangement with John Wiley & Sons

Lunar regolith consists of unconsolidated grains with high porosity, called the fairy castle structure. It is closely linked to the lunar opposition effect, which is the effect where brightness sharply increases as the phase angle approaches 0°. However, owing to the Earth’s gravity, it is difficult to reproduce the structure to study the physical characteristics of the lunar fairy castle structure in the laboratory. We designed a lunar fairy castle structure model for 3D printing. These models had high porosity and were simplified to tree-like shapes. Various porous conditions of the surface were considered, represented by the number of trees, maximum trunk length, and maximum branch angle. In this study, a laboratory experiment was conducted to measure the reflectance of simulants with a fairy castle structure within a small phase angle range from 1.4° to 5.0°. The result is analyzed for the sample porosity with the tangential slope of the reflectance S(α), which denotes the strength of the opposition effect. In addition, the results of this study were compared with lunar observation data. The porous samples exhibited a relatively large S(α) value. The influence of branch length and attachment angle was very weak in this study. Samples with a porosity between 0.78 and 0.82 represent the similar S(α) values to the lunar observation data, a mean porosity of lunar regolith. In conclusion, our findings suggest a potential correlation between porosity and the opposition effect in printed samples, proposing a new research approach for understanding the lunar opposition effect.