¹Lingzhi Sun et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14332]
¹Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Manoa, Honolulu, Hawaii, USA
Published by arrangement with John Wiley & Sons

The double drive tube 73001/2 is a regolith core and was collected on the Light Mantle at Station 3 during the Apollo 17 mission. This core preserves an in situ record of space weathering and compositional stratigraphy, providing insights to the thickness of the Light Mantle and the local regolith reworking time scale. We measured the dissection passes 2–3 of core 73002 and passes 1–3 of core 73001 using a high-spatial resolution multispectral imaging system, and analyzed the space weathering products on individual soil grains from pass 2 of 73002 using transmission electron microscopy analysis. Our results indicate that the double drive tube 73001/2 contains a zone of submature to mature soil overlying a zone of immature soil. The top more mature zone is about 6–7 cm thick, corresponding to the local regolith reworking depth. On the basis of this depth, the estimated regolith reworking time scale for core 73001/2 is approximately 9–13 million years. Due to mixing with basaltic materials from the central valley, the top mature zone exhibits an FeO content 1–3 wt% higher than the underlying immature soils. Spectral images indicate that the double drive tube failed to penetrate the bottom of the Light Mantle but may have reached the edge of the landslide-valley material mixing zone. The local landslide deposit is thicker than the maximum sampling depth of the double drive tube, which is about 70 cm.

^1,2*Craig R. Walton, ³Mahesh Anand, and ¹Maria Schönbächler
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14333]
¹Department of Earth Sciences, Institute f€ur Geochemie und Petrologie, ETH Zurich, Zurich, Switzerland
²Institute of Astronomy, University of Cambridge, Cambridge, UK
³School of Physical Sciences, Open University, Milton Keynes, UK
Published by arrangement with John Wiley & Sons

The majority of ordinary chondrite (OC) meteorites record some amount of textural evidence for impact-induced deformation. Melt veins in some shocked samples have been compared to terrestrial impact-related pseudotachylites, which form by frictional melting of host rock. However, lacking in situ context, the role of friction in driving impact-related melting in meteorites remains unclear. Here, we present evidence for an important role for shear deformation and friction in complementing shock melting of OC material. We find microfaults directly associated with textural evidence for quenched frictional shock melt in samples of a broad range of bulk shock stages and across all three classes studied (LL, L, or H). Microfaults occur in 20% of our studied samples. We identify examples of both individual microfaults and, in rare cases, microfault networks, complete with subsidiary shear structures. Our observations indicate that friction plays an important role in melt generation in weakly to moderately shocked samples and may also be relevant for strongly shocked meteorites. Microfault structures may be of underestimated significance in chondrites in general—both with regard to their general abundance and their possible utility for elucidating the geological settings sampled by meteoritic impactites.

¹Christina M. Verhagen et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14331]
¹Department of Earth and Planetary Sciences, Rutgers University, Piscataway Township, New Jersey, USA
Published by arrangement with John Wiley & Sons

Large terrestrial impacts may produce vast subsurface hydrothermal systems, capable of generating conditions favorable to the origin of life. Modeling suggests that these systems may persist for >1 million years for basin-sized craters; however, direct experimental constraints on hydrothermal system duration are needed. Paleomagnetism may be used as a tool to study the nature and duration of the postimpact hydrothermal system generated within the upper peak ring of the 200 km diameter Chicxulub crater (Yucatán Peninsula, México). Previous work observed that upper peak ring suevite samples contained characteristic remanent magnetizations with negative and positive inclinations, with most samples having a magnetic inclination close to −44°, the expected paleoinclination at the crater at the time of the impact. This magnetic record was at the time interpreted as chemical remanent magnetization (CRM) acquired over a period of at least 150 thousand years, from the time of the impact in geomagnetic Chron C29r into Chron C29n. We conducted further paleomagnetic and rock magnetic studies of upper peak ring rocks and found that, while most samples likely contain CRM acquired during Chron C29r, the dispersion of magnetic inclinations within suevite subunits is more likely attributed to pre-depositional remanence held within clasts than the recording of magnetic reversals. Therefore, the paleomagnetic record of the peak ring suevites is non-ideal for inferring the duration of the Chicxulub postimpact hydrothermal system.

¹Fei Su et al. (>10)
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2024JE008495]
¹Key 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 landing site provides an important window into the Moon’s late Eratosthenian period of volcanism at ∼2 Ga. Clarifying the Moon’s history of volcanic activity using radioisotopic dating assists investigations of the evolution of the lunar surface as well as the Moon’s internal dynamics. Recent chronological investigations of Chang’e-5 basalts produced ages spanning ∼100 Ma, thereby inhibiting interpretation of the duration of volcanism recorded in the returned samples. We used microcomputed tomography and Back-Scatter Electron imaging to characterize the structure and morphology of nine Chang’e-5 basalt clasts. Several basalt clasts lack shock features and are interpreted to have not been significantly thermally disturbed. 40Ar/39Ar incremental heating produced well defined plateaus for four sub-split samples that give a weighted mean age of 2,021 ± 17 Ma (2σ). These are among the youngest mare basalts to be dated thus far by the 40Ar/39Ar method and, when combined with most of the published Pb-Pb ages for Chang’e-5 basalts, define a single episode of mare volcanism at ∼2,021 Ma.

¹Zhongtian Zhang,¹Peter E. Driscoll
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2024JE008671]
¹Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC, USA
Published by arrangement with John Wiley & Sons

Some melted and differentiated planetesimals, such as the parent bodies of angrites and howardite-eucrite-diogenite meteorites, are severely depleted in moderately volatile elements (MVEs). The origins of these depletions are critical for understanding early solar system evolution but remain topics of debate. Numerous previous studies have invoked evaporation from magma oceans as a potential mechanism for producing these depletions, yet this process is poorly explored. In this study, we examine the efficiency of MVE loss from planetesimal magma oceans. Upon heating from short-lived A⁢l26, internal magma oceans can develop beneath insulating crusts. The magma oceans may be exposed to the surface by collisional disruption of the crusts, but would be rapidly cooled by the cold environments. The exposed surface would be quenched to solid/glass; even if the quenched skin can be recycled by convection such that the magma ocean can be continuously resurfaced, only a small portion of the surface can remain molten. In the convection boundary layer, “vertical” advection is suppressed, energy and element transports toward the surface occur via thermal and chemical diffusion (if MVEs do not exsolve as bubbles). As chemical diffusivity is much smaller than thermal diffusivity, MVE transport is much less efficient than heat transport, and MVE loss during magma ocean cooling is likely minimal (≲1% the total inventory). Therefore, MVE depletions may not be easily explained by evaporation from A⁢l26-heated planetesimal magma oceans.

¹Chengxiang Yin,^1,2Xiaohui Fu,¹Haijun Cao,¹Xuejin Lu,¹Jian Chen,¹Jiang Zhang,^1,2Zongcheng Ling,³Xiaochao Che
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2024JE008733]
¹Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Technology, Institute of Space Sciences, Shandong University, Weihai, China
²CAS Center for Excellence in Comparative Planetology, Chinese Academy of Sciences, Hefei, China
³Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China
Published by arrangement with John Wiley & Sons

Submicroscopic metallic iron particles (SMFe) are unique components of lunar soil produced during long-term exposure on the Moon’s surface. They can significantly alter the optical properties of lunar soil and this alteration is crucial for the interpretation of remote sensing data. The origin and formation of SMFe remain a subject of controversy, with multiple competing mechanisms coexisting. The newly returned Chang’e-5 (CE-5) samples provide a new opportunity to elucidate the formation of SMFe. Here, we conducted a systematical study on the morphology and chemical characteristics of metal globules in CE-5 impact melt splash. A total of 30,630 metal globules were identified with an average diameter of 222.87 nm. Most of them are nearly/perfectly spherical, but the others are irregular in shape. Three types of irregular metal globules have been found: Spindle type, deformation type, and coalescence type. Spindle and deformation types were formed under the influence of local thermal disequilibrium and/or differences in wettability, while the coalescence type reflects the growth of metal globules driven by the Oswald ripening. A series of metal globules at different coalescence stages were found, providing conclusive petrographic evidence for the long-term hypothesis of SMFe growth (e.g., Pieters & Noble, 2016, https://doi.org/10.1002/2016je005128). Geochemical analysis shows that meteoritic Fe-Ni metals (like iron meteorite) made a significant contribution to the formation of metal globules. This further indicates the contribution of exotic meteoroid materials to the CE-5 lunar soil.

¹P.Beck et al. (>10)
Earth and Planetary Science Letters 656, 119256 Open Access Link to Article [https://doi.org/10.1016/j.epsl.2025.119256]
¹Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
Copyright Elsevier

On Earth, silica-rich phases from opal to quartz are important indicators and tracers of geological processes. Hydrated silica, such as opal, is a particularly good matrix for the preservation of molecular and macroscopic biosignatures. Cherts, a type of silica-dominated rocks, provide a unique archive of ancient terrestrial life while quartz is the emblematic mineral of the Earth’s continental crust. On Mars, hydrated silica has been detected in several locations based on remote sensing and rover-based studies. In the present article we report on the detection of cobbles made of hydrated silica (opal or chalcedony), as well as well-crystallized quartz. These detections were made with the SuperCam instrument onboard Perseverance (Mars 2020 mission), using a combination of LIBS, infrared and Raman spectroscopy. Quartz-dominated stones are detected unambiguously for the first time on the Martian surface, and based on grain size and crystallinity are proposed to be of hydrothermal origin. Although these rocks were all found as float, we propose that these detections are part of a common hydrothermal system, and represent different depths / temperatures of precipitation. This attests that hydrothermal processes were active in and around Jezero crater, possibly triggered by the Jezero crater-forming impact. These silica-rich rocks, in particular opaline silica, are very promising targets for sampling and return to Earth given their high biosignature preservation potential.

¹Fang, Linru,¹Moynier, Frédéric,¹Chaussidon, Marc,¹Limare, Angela,¹Makhatadze, Georgy V.,²Villeneuve, Johan
Science Advances 11, eadp9381 Open Access Link to Article [DOI 10.1126/sciadv.adp9381]
¹Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, 75005, France
²Université de Lorraine, CNRS, CRPG, UMR7358, Nancy, F-54000, France

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^1,5Stude, Joan,¹Aufmhoff, Heinfried,¹Schlager, Hans,^1,2Rapp, Markus,¹Baumann, Carsten,⁴Arnold, Frank,³Strelnikov, Boris
Atmospheric Chemistry and Physics 25, 383-396 Open Access Link to Article [DOI 10.5194/acp-25-383-2025]
¹German Aerospace Center (DLR), Institute of Atmospheric Physics, Oberpfaffenhofen, Germany
²Atmospheric Physics, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
³Leibniz Institute of Atmospheric Physics (IAP), Kühlungsborn, Germany
⁴Max Planck Institute for Nuclear Physics (MPIK), Heidelberg, Germany
⁵Division of Space and Plasma Physics, Royal Institute of Technology (KTH), Stockholm, Sweden

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¹Kareta, Theodore,²Fuentes-Muñoz, Oscar,¹Moskovitz, Nicholas²Farnocchia, Davide,³Sharkey, Benjamin N. L.
Astrophysical Journal Letters 979, L8 Open Access Link to Article [DOI 10.3847/2041-8213/ad9ea8]
¹Lowell Observatory, Flagstaff, AZ, United States
²Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, 91109, CA, United States
³Department of Astronomy, University of Maryland, 4296 Stadium Dr., PSC (Bldg. 415) Rm. 1113, College Park, 20742-2421, MD, United States

The near-Earth asteroid (NEA) 2024 PT5 is on an Earth-like orbit that remained in Earth’s immediate vicinity for several months at the end of 2024. PT5’s orbit is challenging to populate with asteroids originating from the main belt and is more commonly associated with rocket bodies mistakenly identified as natural objects or with debris ejected from impacts on the Moon. We obtained visible and near-infrared reflectance spectra of PT5 with the Lowell Discovery Telescope and NASA Infrared Telescope Facility on 2024 August 16. The combined reflectance spectrum matches lunar samples but does not match any known asteroid types—it is pyroxene-rich, while asteroids of comparable spectral redness are olivine-rich. Moreover, the amount of solar radiation pressure observed on the PT5 trajectory is orders of magnitude lower than what would be expected for an artificial object. We therefore conclude that 2024 PT5 is ejecta from an impact on the Moon, thus making PT5 the second NEA suggested to be sourced from the surface of the Moon. While one object might be an outlier, two suggest that there is an underlying population to be characterized. Long-term predictions of the position of 2024 PT5 are challenging due to the slow Earth encounters characteristic of objects in these orbits. A population of near-Earth objects that are sourced by the Moon would be important to characterize for understanding how impacts work on our nearest neighbor and for identifying the source regions of asteroids and meteorites from this understudied population of objects on very Earth-like orbits.