¹M. J. Burchell,²R. C. Ogliore,¹P. J. Wozniakiewicz
Meteoritics & Planetary Sciences (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70090]
¹Centre for Astrophysics and Planetary Science, School of Engineering, Mathematics and Physics
²University of Kent,Canterbury, Kent, UK2 Department of Physics, University of Central Florida, Orlando, Florida, USA
Published by arrangement with John Wiley & Sons

The desire to sample material from the interior of Io, by flying through its volcanicplumes, requires consideration of the flyby speed and the types of sample collection techniquesthat can be utilized. Low speed collection (1–2.5 km s1) would require an orbit around Io itself,which is unlikely due to the accumulated radiation dose that would be experienced. Moderatecollection speeds (7–9 km s1) are possible for flybys of Io arising from either a single passagethrough the Jovian system (followed by sample return) or a carefully selected orbit aroundJupiter that has the main purpose of visiting Io. However, even if they include an Io closepassage, most Jovian mission orbit concepts also include and even prioritize other scienceobjectives, resulting in orbits with Io collection speeds of around 17–19 km s1 (or greater).Depending on the speed and collector material, the peak shock pressures during collection maythus range from 5 to hundreds of GPa for impacts on solid, nonporous media, with pressuresfrom 0.01 to 5 GPa for impacts on low-density aerogels. These shock pressures are calculatedherein for a range of Io encounter speeds and collector types, and the degree of sample captureand impact processing are estimated. While capture of material is shown to be possible at speedsup to 10 km s1, permitting both in situ analysis or sample return to Earth, above these speedsretention of significant amounts of unvaporized material in a collector is not viable.

^1,2Birger Schmitz,³Yue Cai,^2.4Shiyong Liao,⁵Victoriano Pujalte,³Ting Ruan,⁶Robert P. Speijer,^7,8Ellen Thomas
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70082]
¹Astrogeobiology Laboratory, Department of Physics, Lund University, Lund, Sweden
²Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, China
³State Key Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Chinese Academy ofSciences, Nanjing, China
⁴Chinese Academy of Sciences, Center for Excellence in Comparative Planetology, Hefei, China
⁵Department of Geology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain
⁶Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
⁷Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
⁸Department of Earth and Environmental Sciences, Wesleyan University, Middletown, CT, USA
Published by arrangement with John Wiley & Sons

Almost 10 years have passed since microtektites and microkrystites were reportedfor the Paleocene–Eocene (P–E) boundary in drill cores and outcrop in New Jersey and inODP Hole 1051B in the western North Atlantic. The glassy spherules were interpreted toreflect an impact trigger for the Paleocene–Eocene Thermal Maximum (PETM). Since then,many detailed studies of sediment strata across the P–E boundary worldwide have beenperformed, but so far, no additional reports of impact spherules have been published.Negative results usually are not published, but here we report a lack of success in finding suchspherules at the P–E boundary in ODP Hole 1051B. We searched 90 g of sediment from thesame interval in the same core from which 56 impact spherules >63 lm were previouslyreported from 35 g of sediment, but did not find microtektites or microkrystites. We also didnot find impact spherules in a detailed search of 2.3 kg of sediment from the P–E boundary inthe Zumaia section (Spain), where the boundary is marked by a minor iridium anomaly. Inaddition, we did not find such spherules in P–E boundary sediment from sections in Europeand the Middle East nor in drill cores from the southern Atlantic. We urge the researchcommunity to report further both negative and positive results on this issue in order toelucidate the envisioned P–E boundary impact event.

¹Jingyou Chen, ²Shaolin Li, ³Shiyong Liao, ⁴Jian Chen, ⁵Alexander Nemchin, ⁶Katherine H. Joy, ⁷Xiaochao Che, ³Weibiao Hsu, ⁸Menghua Zhu
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2026.01.007]
¹State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
²Astronomical Research Center, Shanghai Science and Technology Museum, Shanghai, China
³CAS Center for Excellence in Comparative Planetology, Purple Mountain Observatory, Nanjing 210034, China
⁴Shandong Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai 264209, China
⁵School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
⁶Department of Earth and Environmental Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
⁷The Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
⁸State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau
Copyright Elsevier

The increasing identification of magnesian anorthosites (MAN) in lunar meteorites, along with inferences from remote sensing techniques, has intensified research interest in understanding their role in lunar crust formation. However, the lack of robust geochronological constraints for MAN impeded our comprehension of the timeline of crustal evolution. The lunar feldspathic breccia meteorite, Northwest Africa (NWA) 11479, is composed primarily of Mg-rich, KREEP-poor (K, rare earth elements, and P) highland lithic fragments, predominantly consisting of magnesian anorthositic lithologies (including anorthosite noritic/troctolitic anorthosites, and the associated magnesian granulites). The close chemical match between the bulk rock and lunar remote sensing data supports a farside origin, providing evidence for the presence of MAN in the Feldspathic Highlands Terrane (FHT).
Zircon and apatite grains have been discovered within the small Mg-rich anorthositic clasts in NWA 11479. Notably, the occurrence of these highly evolved accessory minerals contrasts with the depletion of incompatible trace elements in the coexisting silicates, suggesting their formation via interactions between the anorthositic crust and a later-stage KREEPy metasomatic melt. In-situ U-Pb isotopic analysis of the zircon and apatite yields a well-defined discordia line, with an upper intercept date of 4328 ± 9 Ma (2σ), and a lower intercept date of 140 ± 64 Ma (2σ). The younger age likely reflects a more recent impact event, whereas the upper intercept is consistent with both the concordant U-Pb zircon date (4327 ± 12 Ma, 2σ) and the weighted average 207Pb/206Pb date of the zircon and apatite (4326 ± 8 Ma, 2σ). This ∼ 4.33 Ga age is interpreted as the timing of metasomatism responsible for the formation of the zircon and apatite, or an impact event. Importantly, this age obtained from the putative-origin meteorite coincides with the period (4.3–4.35 Ga) of the active secondary magmatism recorded in nearside-collected Apollo samples, the proposed formation age of the giant South Pole–Aitken (SPA) basin. These temporal correlations suggest that this epoch represents a major phase of global reworking of the primordial lunar crust, likely driven by the overturn of mantle cumulates and further intensified by basin‑scale impact events, or both.

¹Mingming Zhang, ^1,3Kohei Fukuda, ²Michael J. Tappa, ²William O. Nachlas, ²²Bil Schneider, ⁴Makoto Kimura, ¹Kouki Kitajima, ²Ann M. Bauer, ¹Noriko T. Kita
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.12.056]
¹WiscSIMS, Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706, USA
²Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706, USA
³Graduate School of Science, The University of Osaka, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
⁴National Institute of Polar Research, Meteorite Research Center, Midoricho 10-3, Tachikawa, Tokyo 190-8518, Japan
Copyright Elsevier

Chondrules, ferromagnesium spherules prevalent in undifferentiated extraterrestrial materials, are the main high-temperature products of the protoplanetary disk. Relict minerals within them directly record precursor compositions and thermal histories, offering critical constraints on the long-debated chondrule heating mechanism. We identified pervasive relict refractory anorthites in Al-rich chondrules (bulk Al2O3 ≥10 wt%, ARCs) from pristine carbonaceous chondrites. These anorthites form rims around relict spinel aggregates or intergrow with high-Ca pyroxene/olivine relics, indicating preferential recycling of anorthite-rich inclusions during outer-disk chondrule heating events over more abundant melilite-rich ones. The wide occurrence of relict anorthite, which can be readily melted or dissolved in chondrule melts, suggests these ARCs were most likely formed by one-time crystallization. Thus, their Al-Mg ages of ∼2.0–2.5 Ma after CAIs imply refractory materials were continuously involved over nearly the entire period of chondrule formation. Additionally, we infer that a portion of co-formed iron-poor ferromagnesium chondrules must have similarly escaped completely remelting by subsequent intense heating events in the same reservoirs. These findings suggest that the intense heating events that lead to carbonaceous chondrule formation are localized and infrequent, aligning with mechanisms like bow shocks, lightning discharges, and impact jetting but not the large-scale nebular shocks.

^1,2William F. McDonough
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.12.060]
¹Advanced Institute for Marine Ecosystem Change (WPI-AIMEC), Department of Earth Sciences and Research Center for Neutrino Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
²Department of Geology, University of Maryland, College Park, MD 20742, USA
Copyright Elsevier

One in every two atoms in the Earth, Mars, and the Moon is oxygen; it is the third most abundant element in the solar system. The oxygen isotopic compositions of the terrestrial planets are different from those of the Sun and demonstrate that these planets are not direct compositional analogs of the solar photosphere. Likewise, the Sun’s O/Fe, Fe/Mg and Mg/Si values are distinct from those of inner solar system chondrites and terrestrial planets. These four elements (O, Fe, Mg, Si) make up 90% to 94% by mass (and atomic %) of the rocky planets, and their abundances are determined uniquely using geophysical, geochemical, and cosmochemical constraints.

The rocky planets likely grew rapidly (with    10 million years) from large populations of planetesimals, most of which were differentiated, having a core and a mantle, before being accreted. Planetary growth in the early stages of protoplanetary disk evolution was rapid and was only partially recorded by the meteoritic record. The noncarbonaceous meteorites (NC) provide insights into the early history of the inner solar system and are used to construct a framework for how the rocky planets were assembled. NC chondrites have chondrule ages that are two to three million years younger than  (the age of calcium–aluminum inclusions, CAI), documenting that NC chondrites are middle- to late-stage products of solar system evolution.

The composition of the Earth, its current form of mantle convection, and the amount of radiogenic power that drives its engine remain controversial topics. Earth’s dynamics are driven by primordial and radiogenic heat sources. Measurement of the Earth’s geoneutrino flux defines its radiogenic power and restricts its bulk composition. Using the latest data from the KamLAND and Borexino geoneutrino experiments affirms that the Earth has   20 TW of radiogenic power and sets the proportions of refractory lithophile elements in the bulk silicate Earth at   2.7 times that in CI chondrites. The bulk Earth and the bulk Mars are enriched in refractory elements about 1.9 times that of the CI chondrites. Earth is more volatile-depleted and less oxidized than Mars.

¹Eleanor C. McIntosh, ¹James M.D. Day
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.12.059]
¹Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
Copyright Eslevier

The Apollo 17 high-Ti orange (74220) and Apollo 15 low-Ti green (15426) lunar pyroclastic glasses are some of the most primitive igneous samples from the Moon and are considered critical for understanding the volatile content of the lunar interior. The orange and green glass deposits are petrologically distinct, containing both holohyaline (glassy) and crystallized beads. In this study, edge and center analyses on holohyaline beads representative of the deposits were conducted by laser ablation inductively coupled plasma mass spectrometry to constrain the distribution of moderately volatile elements (MVE: K, Cu, Zn, Cs, Ga, Ge, Rb, Cd, and Pb), and trace element images were produced of the beads in 74220. Bead edges have elevated MVE abundances compared to centers in the larger (107 µm average diameter) low-Ti Apollo 15 green glasses, likely resulting from syn-eruptive processes. Leaching experiments of 15,426 bulk beads support a large fraction of Na, K, Zn, Cd, Cd and Pb on their outer surfaces. The smaller (42 µm average diameter) high-Ti Apollo 17 orange glasses have a greater extent of overlap in MVE contents between bead edges and centers. Orange and green glass bead centers offer approximations of melt MVE abundances, indicating ∼500 µg/g K, ≤20 µg/g Zn, ∼6 µg/g Cu, <4 µg/g Ga and ≤ 1 µg/g Rb and <0.1 µg/g Pb and ≤ 100 µg/g K, ≤1 µg/g Zn, ≤2.5 µg/g Cu, <2 µg/g Ga and ≤ 0.5 µg/g Rb and Pb, respectively. These estimates are as much as ten times lower than bulk bead abundances for these and other MVE within the pyroclastic glass deposits, are depleted compared to terrestrial mid-ocean ridge basalts, and are similar, or lower than, bulk silicate Earth (BSE) concentration estimates. Partial melting estimates for the source of the pyroclastic glass beads indicate similarities with tholeiitic and komatiite lavas on Earth and between ∼10 and 30 % melting of their mantle source, consistent with high mantle potential temperatures at ∼3.5 billion years ago in the Moon. The estimated MVE composition of the orange glass bead mantle source is marginally higher than the green glass mantle source, and both are within or lower than bulk silicate Moon estimates. More shallowly derived mare basalts have been shown to be yet more MVE depleted, indicating that the lunar interior had a heterogeneous distribution of volatile elements, with a deep interior with volatile abundances ∼10 times lower than BSE, volatile-poor upper magma ocean cumulates, and an incompatible volatile-enriched KREEP reservoir.

¹Martin R. Lee,¹Jasper Glazer
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70089]
¹School of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK
Published by arrangement with John Wiley & Sons

Alteration of historic CI1 meteorite falls during their curation demonstrates the susceptibility of smectite-rich carbonaceous chondrites to terrestrial exposure. The discovery of Oued Chebeika 002 in Morocco in June 2024 presents a unique opportunity to document the earliest stages of weathering of a CI1 find. We studied 10–30 mg fragments that had been recovered by September 2024. Grains of quartz and feldspar were implanted into the fragments by wind action whilst on the desert floor. Gypsum is the main product of terrestrial weathering. It encrusts their outer surfaces, in one case covering 5.3% of a fragment, and has filled voids within both fractures and phyllosilicate clasts. Other products of terrestrial weathering are Ca-carbonate grains that have grown within a sand-filled fracture, and rock inhabiting fungi colonizing the surface of a fragment. Chemical weathering was facilitated by water that had been adsorbed by smectite from the humid desert air, and crystallization of gypsum was driven by evaporation from the surfaces of those fragments that were exposed to direct sunlight. The gypsum and Ca-carbonate grew over a period of 3 or 4 months, approximately between June and September 2024, whereas the time scale of fungal colonization can only be constrained to a year or less. The rapid interaction of Oued Chebeika 002 with the Earth’s atmosphere, lithosphere, and biosphere underscores the importance of prompt recovery and careful curation of CI1 and other smectite-rich meteorites.

¹S.James et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70081]
¹Department of Geology, University of Kerala, Thiruvananthapuram, India
²Department of Earth and Planetary Science, University of Tokyo, Tokyo, Japan
Published by arrangement with John Wiley & Sons

At ~66 Ma, the Cretaceous–Paleogene Boundary (KPB) sections at Anjar and Um Sohryngkew (India) were 14,333 and 16,549 km, respectively, from Chicxulub, making them the farthest distal KPBs. The spatial and temporal proximity of the sites to Deccan volcanism makes them important locations to better understand the impact-volcanism debate. This study integrates petrological, mineralogical, and geochemical techniques to distinguish signatures of the instantaneous Chicxulub impact from those of the prolonged Deccan volcanism (lasting ~10 my). The sites contained two ejecta components: a potential spherule (Um Sohryngkew) and Ir-anomalies. The poorly preserved spherule (~240 μm diameter) exhibited mineral dendrites. At Anjar, two Ir-anomalies are noted: 8.50 ppb (SGA-2; ~3.19 m below Flow IV) and 1.16 ppb (SGA-12). Four Ir-anomalies are noted at Um Sohryngkew: 1.36 ppb (SMU-19; 28.44 m from the oldest layer), 3.17 (SMU-14), 7.00 (SMU-7), and 1.19 ppb (SMU-6). Multiple Ir-anomalies, elevated background-Ir, and glass shards at both sites highlight a greater influence of Deccan volcanism than previously recognized. Deccan magma-based Ir-enrichment is unlikely as such values were not reported in Deccan basalts, but higher Ir-concentrations in sedimentary layers point to indirect contributions from Deccan outgassing. Thus, the findings of the study underscore the complex interplay of Deccan volcanism and Chicxulub impact across the Indian Subcontinent.

¹Eleanor C. McIntosh, ¹James M.D. Day
Geochimics et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.12.059]
¹Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
Copyright Elsevier

The Apollo 17 high-Ti orange (74220) and Apollo 15 low-Ti green (15426) lunar pyroclastic glasses are some of the most primitive igneous samples from the Moon and are considered critical for understanding the volatile content of the lunar interior. The orange and green glass deposits are petrologically distinct, containing both holohyaline (glassy) and crystallized beads. In this study, edge and center analyses on holohyaline beads representative of the deposits were conducted by laser ablation inductively coupled plasma mass spectrometry to constrain the distribution of moderately volatile elements (MVE: K, Cu, Zn, Cs, Ga, Ge, Rb, Cd, and Pb), and trace element images were produced of the beads in 74220. Bead edges have elevated MVE abundances compared to centers in the larger (107 µm average diameter) low-Ti Apollo 15 green glasses, likely resulting from syn-eruptive processes. Leaching experiments of 15,426 bulk beads support a large fraction of Na, K, Zn, Cd, Cd and Pb on their outer surfaces. The smaller (42 µm average diameter) high-Ti Apollo 17 orange glasses have a greater extent of overlap in MVE contents between bead edges and centers. Orange and green glass bead centers offer approximations of melt MVE abundances, indicating ∼500 µg/g K, ≤20 µg/g Zn, ∼6 µg/g Cu, <4 µg/g Ga and ≤ 1 µg/g Rb and <0.1 µg/g Pb and ≤ 100 µg/g K, ≤1 µg/g Zn, ≤2.5 µg/g Cu, <2 µg/g Ga and ≤ 0.5 µg/g Rb and Pb, respectively. These estimates are as much as ten times lower than bulk bead abundances for these and other MVE within the pyroclastic glass deposits, are depleted compared to terrestrial mid-ocean ridge basalts, and are similar, or lower than, bulk silicate Earth (BSE) concentration estimates. Partial melting estimates for the source of the pyroclastic glass beads indicate similarities with tholeiitic and komatiite lavas on Earth and between ∼10 and 30 % melting of their mantle source, consistent with high mantle potential temperatures at ∼3.5 billion years ago in the Moon. The estimated MVE composition of the orange glass bead mantle source is marginally higher than the green glass mantle source, and both are within or lower than bulk silicate Moon estimates. More shallowly derived mare basalts have been shown to be yet more MVE depleted, indicating that the lunar interior had a heterogeneous distribution of volatile elements, with a deep interior with volatile abundances ∼10 times lower than BSE, volatile-poor upper magma ocean cumulates, and an incompatible volatile-enriched KREEP reservoir.

^1,2Marine Paquet, ¹James M.D. Day, ³Arya Udry
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.12.019]
¹Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92037, USA
²Université de Lorraine, CNRS, CRPG F-54000 Nancy, France
³Department of Geoscience, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, NV 89154, USA
Copyright Elsevier

The nakhlite and chassignite meteorites are the only confirmed group of rocks derived from a single volcanic system on Mars, offering a unique opportunity to investigate the composition of the martian mantle and magmatic differentiation mechanisms. Nakhlites and chassignites are thought to result from low-degree partial melting of a hydrated and metasomatized depleted mantle lithosphere, unlike shergottites that predominantly sample deeper mantle reservoirs. This study presents the first comprehensive dataset on highly siderophile element (HSE: Au, Re, Pd, Rh, Pt, Ru, Ir, Os) abundances in sulfide assemblages from twelve nakhlites and two chassignites, together with siderophile (Ni, Co, W) and chalcophile (Cu, Se, Zn, Pb) element abundance data. Sulfides in chassignites exhibit relatively high total HSE abundances at ∼ 5 × carbonaceous (CI) chondrite abundances, with patterns that are generally flat, apart from notable enrichments in Pt and/or Ru. Conversely, nakhlite sulfides display more fractionated HSE patterns with total HSE abundances ∼ 1.6 × CI, characterized by lower overall abundances and enrichment in Re, Pt and Pd relative to Ru, Ir and Os. These results confirm that sulfides are the principal reservoirs of HSE in chassignites and nakhlites. Fractionation modeling suggests that the nakhlite compositions can be reproduced following up to 15 % fractional crystallization through the removal of an olivine (+Cr-spinel)-dominated cumulate, while chassignites experienced between 20 to 30 % of fractionation. The preservation of magmatic signatures in sulfide HSE compositions allows for an in-depth reconstruction of the evolution of the nakhlite-chassignite parental melt composition.